Documents published in 2021 : Scipedia

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Godwin barnabas's personal collection (2021). 1

Abstract
We are happy to inform that Admission is open for the academic year 2021-2022 for the following UG and PG programs, B.E Civil Engineering, B.E Computer science Engineering, B.E Electronics and communication Engineering, B.E Electrical and Electronics Engineering, B.Tech AI and Data Science B.E Mechanical Engineering. M.E Computer Science and Engineering M.E Communication Systems.
Abstract
We are happy to inform that Admission is open for the academic year 2021-2022 for the following UG and PG programs, B.E Civil Engineering, B.E Computer science Engineering, B.E [...]
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FIBRE4YARDS: Fibre Composite Manufacturing Technologies for the Automation and Modular Construction in Shipyard_20210608
X. Martinez, D. Sá, D. Behrendt

(Select a year).

Abstract
The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced. This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.
Abstract
The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept [...]
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High-Order Implicit Shock Tracking
M. Zahr

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
Shock tracking, as an alternative method to shock capturing, aims to generate a mesh such that element faces align with shock surfaces and other non-smooth features to perfectly represent them with the inter-element jumps in the solution basis. These methods have been shown to enable high- order approximation of high-speed flows and do not require extensive refinement in non-smooth regions because, once the non-smooth features are tracked by the mesh, the solution basis approximates the remaining smooth features. In previous work, we introduced an implicit shock tracking framework that re-casts the geometrically complex problem of generating a mesh that conforms to all discontinuity surfaces as a PDE-constrained optimization problem. In this talk, we present a number of extensions to the implicit shock tracking method aimed at improving robustness for complex problems.
Abstract
Shock tracking, as an alternative method to shock capturing, aims to generate a mesh such that element faces align with shock surfaces and other non-smooth features to perfectly [...]
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Massively Parallel Anisotropic Mesh Adaptation Applied to Earth Land Elevation
H. Digonnet, N. Aissa, L. Douteau, L. Silva

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Stabilized Space-Time Finite Element Approximations for a Class of Quasilinear Parabolic Problems
I. Toulopoulos

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
In this talk, we present continuous space-time finite element methods for solving quasilinear parabolic problems. We present a discretization error analysis. We present numerical results which confirm the theoretical convergence rate estimates.
Abstract
In this talk, we present continuous space-time finite element methods for solving quasilinear parabolic problems. We present a discretization error analysis. We present numerical [...]
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A kernel Proper Orthogonal Decomposition (kPOD) for Nonlinear Dimensionality Reduction of Parametric Problems
A. Muixí, P. Díez, S. Zlotnik, A. Garcia

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Oscillation in a Posteriori Error Estimation
A. Veeser, C. Kreuzer

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
In a posteriori error analysis, the relationship between error and estimator is usually spoiled by so-called oscillation terms, which cannot be bounded by the error. In order to remedy, we devise a new approach where the oscillation has the following two properties. First, it is dominated by the error, irrespective of mesh fineness and the regularity of data and the exact solution. Second, it captures in terms of data the part of the residual that, in general, cannot be quantified with finite information. The new twist in our approach is a locally stable projection onto discretized residuals. In the case of the Poisson problem, the approach leads to an improved standard residual estimator and allows tackling problems with sources in H-1.
Abstract
In a posteriori error analysis, the relationship between error and estimator is usually spoiled by so-called oscillation terms, which cannot be bounded by the error. In order [...]
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Tailored Mesh Generation for NEFEM
X. Zou, R. Sevilla, O. Hassan, K. Morgan

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Modeling Yarn Reorientation in Woven Composites under Off-axis Tensile Loading with Cohesive Zone Based Conformal Meshing
A. Li, B. Wintiba, J. Remmers, M. Geers, T. Massart

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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A Posteriori Error Estimation via Equilibrated Stress Reconstruction for Unilateral Contact Problems
I. Fontana, D. Pietro, K. Kazymyrenko

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
We present an a posteriori error estimation based on a equilibrated H(div)-conforming stress reconstruction for unilateral contact problems without friction, discretized with a Nitsche-based method. The stress reconstruction is obtained via local Neumann problems constructed on Arnold-Falk-Winther mixed finite element spaces, and it is used to compute some local and global estimators which separate the different components of the computational error. These local estimators provide a method to adaptively refine the mesh.
Abstract
We present an a posteriori error estimation based on a equilibrated H(div)-conforming stress reconstruction for unilateral contact problems without friction, discretized with [...]
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A Coupled HDG-FV Method for Unsteady Compressible Flows
S. Komala, R. Sevilla, O. Hassan

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Certified Computations with PGD Model Reduction in the MsFEM Framework
F. Legoll, L. Chamoin

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Stabilised Updated Lagrangian SPH for Fast Solid Dynamics
P. Campos

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
This work is part of the ProTechTion project funded by MSCA - EU Horizon 2020, and consists of an Incremental Updated Lagrangian Smooth Particle Hydrodynamics (SPH) framework, aimed at applications in the field of fast solid dynamics, with the following highlights: - Mixed-based system of first-order conservation laws - Incremental ULF (multiplicative decomposition of the deformation) - Anisotropic updated kernel function - Entropy-stable Riemann-based stabilisation scheme.
Abstract
This work is part of the ProTechTion project funded by MSCA - EU Horizon 2020, and consists of an Incremental Updated Lagrangian Smooth Particle Hydrodynamics (SPH) framework, [...]
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Component-Based Model Order Reduction for THM Coupled Problems
A. Iollo, G. Sambataro, T. Taddei

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Design Tool for the Actuation Control of a Micro Fluidic Valve Using Fluid-Structure Interaction Partitioned Approach
A. Berraies, F. Auricchio, H. Brummelen, F. Butera

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Embedding Domain Discretization for Coupled Topology and Shape Optimization
G. Stankiewicz, C. Dev, P. Steinmann

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Testing Scenarios on Geological Models: Local Interface Insertion in a 2D Mesh and its Impact on Seismic Wave Simulation
C. Legentil, J. Pellerin, P. Cupillard, G. Caumon

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
In this work, we consider a relatively simple case of fluid monitoring in a subsurface gas reservoir. Seismic wave velocities for porous rocks vary depending on fluid saturation, and our objective is to quantitatively evaluate the impact of the water/gas contact depth on elastic wave propagation. To efficiently test different contact depth scenarios and assess their impact on wave propagation, we propose to locally modify a 2D geological model and run time-dependent elastic simulations. The input model is a triangulated surface conforming to geological structures and representing physical properties. The 2D meshed model is locally updated, meaning that only a given region is modified and that the other parts of the mesh remain identical. To create several models by modifying only the reservoir layer, we insert a water/gas contact defined by a level-set at several depths with MMG. During the insertion, specific care is taken to maintain the conformity of the output mesh. As compared to global remeshing, the local modification reduces the cost of recomputing physical properties over the updated mesh. We run the numerical simulations by using Hou10ni2D code, which is based on a Discontinuous Galerkin method. Our results on a gas reservoir show a consistent behavior: we observe a correlation between the depth difference and L2-norm, the larger the distance from the reference depth contact, the higher the L2-norm. This approach could therefore be integrated into an inversion loop to determine the position of the fluid contact and reduce uncertainties in the reservoir model.
Abstract
In this work, we consider a relatively simple case of fluid monitoring in a subsurface gas reservoir. Seismic wave velocities for porous rocks vary depending on fluid saturation, [...]
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Computational Model for Large Volume Expansion and Self-Contact with Adaptive Meshing
A. Satheesh, C. Meier, W. Wall

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Moving Mesh Methods for Implicit Moving Boundary Problems
M. Hubbard

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
This talk will present a method for achieving arbitrarily high orders of accuracy when approximating PDE-based moving boundary problems using finite element (and related) methods on moving computational meshes. Its effectiveness will be demonstrated on a nonlinear diffusion problem for which the boundary velocity is only defined implicitly as part of the PDE problem. In this situation high-order approximations can be achieved for both the movement of the boundary and the update of the evolving solution on the moving mesh.
Abstract
This talk will present a method for achieving arbitrarily high orders of accuracy when approximating PDE-based moving boundary problems using finite element (and related) [...]
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Certification, Adaptivity, and Reduction in Non-Intrusive Model Couplings
A. Verwee, L. Chamoin

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
The non-intrusive coupling method is a local analysis method that aims to separate the macroscopic and local scales both from mesh, operator, and loading viewpoints. This method has demonstrated that it can be used for a large set of problems such as those with local plasticity, and it has been implemented in an industrial code. In order to reduce the complexity of a given problem, a coarse model is defined on the total domain with its properties (geometry, connectivity, operator, solver) and a separated fine model is set locally with its different properties. The solution is obtained iteratively by exchanging data on the interface between the global and local models. However, the issue of certification and optimal driving of such a coupling method has been addressed in very few works until now. In the present work, we tackle this subject using the concept of constitutive relation error (CRE) which is a generic tool able to certify the quality of a numerical solution. The main goal is to control the solution of the non-intrusive global-local algorithm, in terms of global error or error in specific quantities of interest, and to optimally drive the coupling algorithm according to quantitative error indicators on individual error sources (discretization, modelling, iterative scheme). In this context, we will also study the coupling between a global solution raised from the well-known Finite Element Method and a local solution evaluated on-line from a virtual chart [4] constructed offline from a reduced order model in the local area of interest. Such a virtual chart is based on the PGD technique and integrates as variables (i.e. extra-parameters) some features of the local model such as boundary conditions, geometry, or material behavior. Complementing the non-intrusive global-local coupling with local ROM leads to a more flexible exchange between interface quantities, and higher performance in terms of computational efficiency and stability. The talk will start with an overview of the methodology of non-intrusive coupling methods, before presenting the error estimation procedure using the CRE concept and its decomposition into various source contributions for adaptive control. Eventually, the construction and the performance of ROM in the non-intrusive coupling method will be studied and discussed.
Abstract
The non-intrusive coupling method is a local analysis method that aims to separate the macroscopic and local scales both from mesh, operator, and loading viewpoints. This [...]
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A New Shape Calculus for CutFEM Discretizations
M. Berggren

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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On Solid-Fluid Mixture Models for High Particulate Volume Fractions
A. Acri, M. Kronbichler, A. Garcia, P. Díez, W. Wall

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Assimilation Capabilities of the IRI-Plas Model
O. Maltseva

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
Proposed method to investigate the ionospheric condition during disturbances by means of assimilation of total electron content into IRI-Plas model
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An a Posteriori Error Estimator for Analysis-Based Defeaturing
A. Buffa, O. Chanon, R. Hernandez

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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A Weighted Shifted Boundary Method for Free Surface Flows
G. Scovazzi, O. Colomés, A. Main, L. Nouveau

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
The Shifted Boundary Method (SBM) belongs to the class of unfitted (or immersed, or embedded) finite element methods and was recently introduced for the Poisson, linear advection/diffusion, Stokes, Navier-Stokes, acoustics, and shallow-water equations, and many additional problems [1, 2]. By reformulating the original boundary value problem over a surrogate (approximate) computational domain, the SBM avoids integration over cut cells and the associated problematic issues regarding numerical stability and matrix conditioning. Accuracy is maintained by modifying the original boundary conditions using Taylor expansions. Hence the name of the method, that shifts the location and values of the boundary conditions. We extend here the SBM to the simulation of incompressible Navier-Stokes flows with moving free-surfaces, by appropriately weighting its variational form with the elemental volume fraction of active fluid [3]. This approach prevents spurious pressure oscillations in time, which would otherwise be produced if the total active fluid volume were to change abruptly over a time step. In fact, the proposed weighted SBM method induces small mass (i.e., volume) conservation errors, which converge quadratically in the case of piecewise-linear finite element interpolations, as the grid is refined. We present an extensive set of two- and three-dimensional tests to demonstrate the robustness and accuracy of the method. References [1] Alex Main and Guglielmo Scovazzi. The Shifted Boundary Method for embedded domain com- putations. Part I: Poisson and Stokes problems. Journal of Computational Physics, 372:972–995, 2018. [2] Alex Main and Guglielmo Scovazzi. The Shifted Boundary Method for embedded domain computations. Part II: Linear advection–diffusion and incompressible Navier–Stokes equations. Journal of Computational Physics, 372:996–1026, 2018. [3] O Colomés, AG Main, L Nouveau, G Scovazzi. A Weighted Shifted Boundary Method for Free Surface Flow Problems. Journal of Computational Physics, doi: https://doi.org/10.1016/j.jcp.2020.109837. The support of the U.S. Department of Energy, Office of Science, the U.S. Office of Naval Research, and ExxonMobil Upstream Research Company (Houston, TX) are gratefully acknowledged.
Abstract
The Shifted Boundary Method (SBM) belongs to the class of unfitted (or immersed, or embedded) finite element methods and was recently introduced for the Poisson, linear advection/diffusion, [...]
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Industrial Application of Adaptive Grid Refinement - The Case of FINE/Marine
J. Wackers

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
This paper studies the introduction of adaptive grid refinement in the FINE/Marine simulation suite, in order to analyse the aspects of a mesh adaptation method which can dissuade, or encourage, industry users to adopt it.
Abstract
This paper studies the introduction of adaptive grid refinement in the FINE/Marine simulation suite, in order to analyse the aspects of a mesh adaptation method which can [...]
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A New mCRE-DDM Based Approach for Model Updating in Structural Dynamics with Industrial Applications
Z. Samir, L. Chamoin, M. Abbas

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Super-Elements and Flexibility Methods Exploiting Hybrid Equilibrium Formulations
E. Maunder, J. Almeida

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
We describe the formulation of a "super" macro equilibrium element which is free from spurious kinematic modes, and can provide a dual solution to a conforming displacement model in the context of error analysis. Details and numerical examples are given for 2D problems involving plane stress. It is intended to extend the formulation to 3D hexahedral elements for modelling solids using reduced numbers of degrees of freedom at the interfaces.
Abstract
We describe the formulation of a "super" macro equilibrium element which is free from spurious kinematic modes, and can provide a dual solution to a conforming displacement [...]
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Efficient Simulation of Crack Propagation in Complex Geometries using a Phase-Field Model and the Finite Cell Method
L. Hug, S. Kollmannsberger, J. Kirschke, M. Potten, G. Stockinger, K. Thuro, Z. Yosibash, E. Rank

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Phase-field Modeling of Brittle Fracture and its Adaptive Moving Mesh Solution
W. Huang

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
The phase-field modeling and its adaptive moving mesh solution for studying initiation and propagation of brittle fracture will be presented. Challenges such as non-smoothness of the energy functional, violation of fracture boundary conditions, and the need for mesh adaptation, and possible remedies for these challenges will be discussed. In particular, a moving mesh finite element method will be presented for the numerical solution of the phase-field model for brittle fracture.
Abstract
The phase-field modeling and its adaptive moving mesh solution for studying initiation and propagation of brittle fracture will be presented. Challenges such as non-smoothness [...]
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An Adaptive Method for the Numerical Solution of a 2D Monge-Ampère Equation
A. Caboussat, D. Gourzoulidis, M. Picasso

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
We consider a 2D parabolic Monge-Ampère equation, and aim at tracking stationary solutions. A time-stepping algorithm is advocated, together with a finite element space approximation. A mesh adaptation technique is considered to track the singularities of the solutions. The approximate error indicator is based on a linearization of the Monge-Ampère operator. Numerical experiments show the numerical efficiency of the approach on several examples.
Abstract
We consider a 2D parabolic Monge-Ampère equation, and aim at tracking stationary solutions. A time-stepping algorithm is advocated, together with a finite element space [...]
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A Real Time Variational data Assimilation Method Based on Complexity Reduction and On-the-fly Data Driven Empirical Enrichment
W. Haik, Y. Maday, L. Chamoin

10th International Conference on Adaptative Modeling and Simulation (ADMOS).

Abstract
The Parameterized Background Data-Weak (PBDW) method is a non-intrusive, reduced basis, real-time and in-situ data assimilation framework for physical systems modeled by parametrized Partial Differential Equations for steady-state problems. The key idea of the formulation is to seek an approximation to the true field employing projection-by-data, with a first contribution from a deduced background estimate from reduced modeling and a second contribution from an update state informed by the experimental observations (correction of model bias). The present study aims at extending the PBDW formulation for time-dependent problems and proposes a sequential version to deal with sampled data. The work focuses on a time integration in the reduced order model, a data-driven empirical enrichment of the model and a state prediction for future time steps.
Abstract
The Parameterized Background Data-Weak (PBDW) method is a non-intrusive, reduced basis, real-time and in-situ data assimilation framework for physical systems modeled by parametrized [...]
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Goal-Oriented Inverse Analysis - Application to Building Thermal Problems
L. Chamoin, Z. Djatouti, J. Waeytens, P. Chatellier

10th International Conference on Adaptative Modeling and Simulation (ADMOS).
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Analysis of Aggression Tendencies Elite Athletes Karate in Turkey
A. Arisoy, M. Koç, A. Akpinar, D. Özsaraç, D. Sofyan

Indonesian Journal of Sport Management (2021). 1

Abstract
The aim of this study is to examine the aggression tendencies of elite karate athletes according to some variables. The sample group of the study was composed of 160 karate athletes selected voluntarily among 400 karate athletes who reached the level of nationality. In the study, the participants were asked to fill in the socio-demographic information form and the Buss and Perry Aggression scale. The analysis of the data was done in computer environment. The arithmetic, mean and standard deviation of the scores the participants got from the scale are presented as x±sd. For paired comparisons, t-test for independent variables and anova were used for more than two comparisons. LSD test was applied to reveal a significant difference in more than two comparisons. The level of significance was accepted as p <0.05. As a result, karateists aggressive tendencies are above average, A statistically significant difference was found among the subtitles in physical aggression, physical aggression and aggression total scores according to nationality of according to gender. It is thought that this situation is caused by the physical and psychological influences of elite athletes are exposed to before, during or after the competition.
Abstract
The aim of this study is to examine the aggression tendencies of elite karate athletes according to some variables. The sample group of the study was composed of 160 karate [...]
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¿Cómo el diagnóstico temprano de la insuficiencia valvular cardiaca puede prevenir una cirugía mayor?
E. Guzmán

Collection of Heart & Vasculature (2021). 1

Abstract
Explicando a fondo las diferentes enfermedades valvulares, su diagnóstico, tratamiento y cómo podemos prevenirlas. Efectos y riesgos de someterse a una cirugía.
Abstract
Explicando a fondo las diferentes enfermedades valvulares, su diagnóstico, tratamiento y cómo podemos prevenirlas. Efectos y riesgos de someterse a una cirug[...]
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A fully Lagrangian formulation for fluid-structure interaction problems with free-surface flows and fracturing solids (preprint)
A. Cornejo, A. Franci, F. Zárate, E. Oñate

Computers & Structures (2021). Vol. 250, 106532

Abstract
This paper presents a novel coupled formulation for fluid-structure interaction (FSI) problems involving free-surface fluid flows, fracture phenomena, solid mutual contact and large displacements. The numerical formulation combines three different Lagrangian computational methods. The Particle Finite Element Method (PFEM) is used to solve the free-surface fluid flow, a Finite Element Method (FEM) with smoothed isotropic damage model is employed for the solution of solid structures and debris, finally, the Discrete Element Method (DEM) is used to manage the contact interaction between different solid boundaries, including the new ones generated by propagating cracks. The proposed method has a high potential for the prediction of the structural damages on civil constructions caused by natural hazards, such as floods, tsunami waves or landslides. Its application field can also be extended to fracture phenomena in structures and soils/rocks arising from explosions or hydraulic fracking processes. Several numerical examples are presented to show the validity and accuracy of the numerical technique proposed.
Abstract
This paper presents a novel coupled formulation for fluid-structure interaction (FSI) problems involving free-surface fluid flows, fracture phenomena, solid mutual contact [...]
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Semi-Lagrangian formulation for the advection–diffusion–absorption equation (preprint)
A. Puigferrat, M. Masó, I. de-Pouplana, G. Casas, E. Oñate

Computer Methods in Applied Mechanics and Engineering (2021). Vol. 380, 113807

Abstract
We present a numerical method for solving advective–diffusive–absorptive problems with high values of advection and absorption. A Lagrangian approach based on the updated version of the classical Particle Finite Element Method (PFEM) is used to calculate advection, while a Eulerian strategy based on the Finite Element Method (FEM) is adopted to compute diffusion and absorption. The Eulerian FEM procedure is based on a Finite Increment Calculus (FIC) stabilized formulation recently developed by the authors. The most relevant features of each computational approach are outlined and the coupling scheme is explained. Several problems are solved to validate the method: the evolution of a localized concentration field in two dimensions (2D), the evolution of a spherical field in 3D and three benchmark problems from the literature with high absorption.
Abstract
We present a numerical method for solving advective–diffusive–absorptive problems with high values of advection and absorption. A Lagrangian approach based [...]
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The Pseudo-Direct Numerical Simulation method for multi-scale problems in mechanics
S. Idelsohn, J. Giménez, N. Nigro, E. Oñate

Computer Methods in Applied Mechanics and Engineering (2021). Vol. 380, 113774

Abstract
We present an overview of the Pseudo-Direct Numerical Simulation (P-DNS in short) method for the solution of multi-scale phenomena. The method can be seen as an adaptation of the variational multi-scale (VMS) method, where the fine solution is solved numerically instead of analytically. Also, from the point of view of homogenization methods it can be seen as an evolution of Finite Element square (FE2) methods, where the most expensive part of the computations is performed offline. The name of P-DNS arises from the premise that in all multi-scale simulations the numerical result obtained with a very fine discretization is correct without the need to introduce any additional model (i.e. turbulence models) or stabilization procedures for transport equation terms (as in residual-based VMS methods). What is intended here is that the P-DNS solution tends to the DNS solution of the problem, accepting as a premise that the DNS solution is a reliable result. In this paper we present first an overview of the P-DNS methodology in the context of an abstract Dirichlet problem involving a second order differential operator that could be non-symmetric and non-necessarily positive definite. Next, the P-DNS approach is applied to the fluid mechanics equations accounting for turbulent phenomena. Examples showing the applicability of the P-DNS method for solving transport problems involving different scales are then presented.
Abstract
We present an overview of the Pseudo-Direct Numerical Simulation (P-DNS in short) method for the solution of multi-scale phenomena. The method can be seen as an adaptation [...]
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Detection and Quantification of Delamination Failures in Marine Composite Bulkheads via Vibration Energy Variations
C. Pariente, A. Jurado Fuentes, P. Beltran

(2021).

Abstract
his paper proposes a new vibration-based structural health monitoring method for the identification of delamination defects in composite bulkheads used in small-length fiber-based ships. The core of this work is to find out if the variations of vibration energy can be efficiently used as a key performance indicator for the detection and quantification of delamination defects in marine composite bulkheads. For this purpose, the changes of vibrational energy exerted by delamination defects in sandwich and monolithic composite panel bulkheads with different types of delamination phenomenon are investigated using a non-destructive test. Experiments show that the overall vibration energy of the bulkheads is directly dependent on the damage conditions of the specimens and therefore, the variations of this parameter are a good indicator of the incorporation of delamination defects in composite bulkheads. Additionally, the overall vibration energy changes also give interesting information about the severity of the delamination defect in the panels. Hence, this methodology based on vibratory energy can be used to accurately determine delamination defects in medium-sized composite bulkheads with the advantages of being a simple and cost-effective approach. The findings of this research possess important applications for the identification of delamination failures in composite components such as bulkheads, turbine blades, and aircraft structures, among others.
Abstract
his paper proposes a new vibration-based structural health monitoring method for the identification of delamination defects in composite bulkheads used in small-length fiber-based [...]
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'''The Feasibility of Turkey’s Accession to the Shanghai Cooperation Organization in Response to the EU's Procrastination in Turkey’s Membership in the European Union'''
Y. Ghobadi Gholoujeh, H. Ghasemi, Y. ghobadi

Collection of Sociological Proceeding (2021). 1

Abstract
The purpose of the present study is to examine the feasibility of Turkey’s accession to the Shanghai Cooperation Organization in response to the EU's procrastination in Turkey’s membership in the European Union. In recent decades, Turkey has done a great deal of work for joining European countries. The formal request of Turkey to join the European Community was presented on April 24, 1987. Turkey's accession to the European Union, on account of some contradictions and conflicts has created special complexities for the parties. A number of analysts consider its specific social and cultural structure as the fundamental barrier for accession Turkey to the European Union and with Turkey's membership, the European Union will not succeed in its identical harmonization process, and it will increase the diversity, variety and differences in the EU. The lack of necessary dynamics in Turkey's political system and society prevents it from acting as a bridge between the East and the West. Therefore, this opposition will exist as long as current variables dominate the political, cultural and social life of the two sides. Shanghai Cooperation organization as a regional organization was established in 2001. The organization, with Russia and China present, is the largest non-Western organization in the Eurasia region. The role of this organization has increased since the beginning of the third millennium in the context of regional and global developments and various analyses have been presented by experts and politicians about its goals, performance and future. Copenhagen's political criterion call for democracy, the full implementation of the rule of law, human rights, labor rights, minority rights, gender equality, participation and pluralism in Turkey. Erdogan not only distanced himself from democratic principles, but also stated that he has shared values with the Shanghai Cooperation Organization.
Abstract
The purpose of the present study is to examine the feasibility of Turkey’s accession to the Shanghai Cooperation Organization in response to the EU's procrastination [...]
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Preliminary Evaluation of the Dearomatization Capacity of Bacterial Isolates on a Renery Current (Light Cycle Oil)
F. Gómez, L. Puentes, A. Sisto, A. Porco, P. Bentancourt

Evaluación preliminar de la capacidad de desaromatización de aislados bacterianos sobre una corriente de refinería (Light Cycle Oil) (2020). Vol. 6, N◦ 19, 128–136

Abstract
Light Cycle Oil (LCO) is a by-product of Fluidized Catalytic Fractionation (FCC) considered a poor-quality diesel due to its high content of sulfur (3 % by weight) and aromatic compounds (50-80 % by weight) which has been enhanced by i) aromatic saturation (ASAT), ii) mild hydrocracking, and iii) aromatic saturation followed by selective ring opening (SRO) of naphthenic structures. On the other hand, it have been reported that different bacterial genera degrade aromatic compounds in a simple and economical way. Consequently, in this work, the ability of bacterial isolates to degrade naphthalene and other aromatic compounds present in an LCO from the Puerto La Cruz refinery (Anzoátegui State-Venezuela) was evaluated. Using UV-Visible spectroscopy, a decrease in naphthalene present in the LCO was observed from 24 to 44 % approximately and by Fourier Transform Infrared spectroscopy, a decrease in aromatic compounds from 27 to 45 %. The results suggest that the bacterial isolates evaluated are capable of using the aromatic compounds present in the LCO as a source of carbon and energy, leaving their consequent effect on the quality of the LCO obtained to be evaluated.
Abstract
Light Cycle Oil (LCO) is a by-product of Fluidized Catalytic Fractionation (FCC) considered a poor-quality diesel due to its high content of sulfur (3 % by weight) and aromatic [...]
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Geothermal Energy, Minero-Medicinal Sources
C. en Revolución

Energía geotérmica, fuentes minero-medicinales (2020). Vol. 6, Nro. 19, 121-127

Abstract
Geothermal energy is presented through different sources and has various uses, such as hot springs, which can be classified based on geological origin (magmatic and telluric), temperature and composition depending of the dissolution of different minerals, coming from the soil and rocks from which they emerge. The natural waters, with known and proven therapeutic properties, are called mineral-medicinal sources. Its therapeutic activity varies according to the ions present in solution, this can be used in numerous pathologies and conditions But geothermal energy is not only limited to this use, it can be used as a heating source at domestic and industrial level. On the other hand, among the great applications of this type of energy is the generation of electricity. Keywords: thermal waters; geothermal energy; mineral-medicinal sources.
Abstract
Geothermal energy is presented through different sources and has various uses, such as hot springs, which can be classified based on geological origin (magmatic and telluric), [...]
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Cold Fusion by Cherenkov Radiation in a Unique Ceramic
R. Barsoum, . PhD, . PE

Cold Fusion in Ceramic (2021).

Abstract
Cold Fusion can be generated by a unique Ceramic of Hydrated Alkali Aluminum Silicates (Ref. 2). We have shown that a standard battery electrolyte can be used with either Lithium or Lead batteries. Some of the major application is to generate clean energy for Unmanned Vehicles, cars and many public transportations vehicles giving them unlimited range of operations.
Abstract
Cold Fusion can be generated by a unique Ceramic of Hydrated Alkali Aluminum Silicates (Ref. 2). We have shown that a standard battery electrolyte can be used with either [...]
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Assimilation capabilities of the IRI-Plas model
O. Maltseva

Olga Maltseva's personal collection (2021). 1

Abstract
In studies of the ionosphere, empirical models play no less a role than experimental data. The most common is the IRI model [1], which describes well the behavior of such parameters as the critical frequency foF2 and the maximum height hmF2. The model allows assimilation of these parameters while adapting to the data of the current diagnostics. But in connection with the appearance of navigation satellites and the measurement of the total electronic content TEC, the IRI-Plas model appeared, which allows the assimilation of the TEC [2]. This can provide great advantages in studying the behavior of the ionosphere, in particular, the parameter foF2, during disturbances along the meridians. One of the possible approaches is assimilation of the IRI-Plas model to the latitudinal dependence of TEC. To test this approach, it is proposed to use a network of ionosondes along the meridian. The ionosonde data at each point is used to calculate the equivalent slab thickness τ of the ionosphere, and from its values at these points, a polynomial latitudinal dependence of τ is constructed. Using this dependence and the observational TEC values along the meridian, the foF2(rec) values calculated using τ and foF2(Plas) obtained by assimilation of the TEC into the IRI-Plas model are determined and compared. The effectiveness of this procedure is illustrated by the example of the 15° E meridian and the known disturbances of March 2012. Five ionosondes are located along this meridian: Longyearbyen, Tromso, Juliusruh, Pruhonice, Rome. According to the data of these ionosondes, it was shown that the frequencies foF2(rec) correspond to the observational values of foF2(obs) with absolute deviations |foF2(rec)| in the range of 0.3-0.4 MHz. To determine the TEC, JPL global maps are used in the range of 30° N-80° N with a step of 2.5°. These values are substituted into the IRI-Plas model and the foF2(Plas) values are calculated. To assess the efficiency of assimilation, two coefficients are introduced: η(TEC) = TEC(obs)/TEC(Plas) and η(foF2) = foF2(rec)/foF2(Plas). In the latitudinal course, the relative error can be defined as (1-1/η)*100%. The absolute TEC deviations were in the range of 0.5-1 TECU, the relative deviations were in the 3.5-6% range and increased with increasing latitude. For foF2, an additional comparison with the IRI model is given. IRI-Plas always gives better results than IRI. For latitudes exceeding 45° N, |ΔfoF2(Plas)| varies from 0.6 MHz to 0.2 MHz with increasing latitude, for IRI it is almost constant (~ 0.5 MHz), the relative deviations for foF2(Plas) decrease from 10% to 5%, for IRI, they are almost constant around 10%. A noticeable increase is observed at low latitudes. Despite the fact that the difference between the results of IRI-Plas and IRI is only 1.5-2 times, it should be noted that IRI-Plas reflects the nature of disturbances much better. The constructed successive latitudinal dependences of foF2(Plas) show day-to-day variations that are in good agreement with the behavior of foF2 in individual latitudinal zones noted in separate papers. Thus, this approach can be used to study variations in foF2 during disturbances on the meridians not provided by ionosondes. REFERENCES D. Bilitza, D. Altadill, V. Truhlik, et al., “IRI 2016: From ionospheric climate to real-time weather predictions,” Space Weather, Vol. 15, pp. 418 – 429, (2017). T.L. Gulyaeva, X. Huang, and B.W. Reinisch, “Plasmaspheric extension of topside electron density profiles”, Adv. Space Res., Vol. 29(6), pp. 825-831. (2002).
Abstract
In studies of the ionosphere, empirical models play no less a role than experimental data. The most common is the IRI model [1], which describes well the behavior of such [...]
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Numerical prediction of the distribution of black carbon in a street canyon using a semi-Lagrangian finite element formulation
A. Puigferrat, I. de-Pouplana, F. Amatto, E. Oñate

Building and Environment (2021). Vol. 199, 107910

Abstract
We present a procedure for coupling the uid and transport equations to model the distribution of a pollutant in a street canyon, in this case, black carbon (BC). The fluid flow is calculated with a stabilized finite element method using the Quasi-Static Variational Multiscale (QS-VMS) technique. For the temperature and pollutant transport we use a semi-Lagrangian procedure, based on the Particle Finite Element Method (PFEM) combined with an Eulerian method based on a Finite Increment Calculus (FIC) formulation. Both methods are implemented on the open-source KRATOS Multiphysics platform. The coupled numerical formulation is applied to the prediction of the transport of BC in a street canyon, which can be a useful tool to lessen the impact of pollutants on pedestrians. Two test cases have been studied: a 2D simplified case and a more complex 3D one. The main goal of this study is to propose a useful tool to study the effect of pollution on pedestrians in a street-level scale. Good comparison with experimental results is obtained.
Abstract
We present a procedure for coupling the uid and transport equations to model the distribution of a pollutant in a street canyon, in this case, black carbon (BC). The fluid [...]
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Exercise Motivation Levels on Student Activity Unit (UKM Basketball) at Universitas Djuanda
I. Review

INSPIREE: Indonesian Sport Innovation Review (2021). https://www.inspiree.review/index.php/inspiree/article/view/41/33

Abstract
The purpose of the study. This study aims to determine how high the level of training motivation of athletes when carrying out training. The background of this research is the inconsistency level of achievement shown by the Basketball Student Activity Unit, Djuanda University, Bogor. Materials and methods. This research was conducted with a quantitative approach, through descriptive methods using a survey method of the basketball team members consisting of 20 people. Data in the form of questionnaire values on the Likert scale were processed using simple statistics SPSS Version 26 to determine the value of descriptive statistics as the final result of the study. Results. The results showed that the level of motivation of athletes who took part in training at the basketball Student Activity Unit (UKM) at Djuanda University, Bogor was in the moderate majority. This result is based on the consideration that the highest frequency is in the medium criteria of 40%. Motivation of athletes in the criteria is very high by 5%, 20% high, 20% less and 15% very less. Conclusions. The percentage of motivation revealed from this study was dominated by the medium category, with a percentage that was less than the high percentage 25% <35%. This can be taken into consideration to be able to evaluate the psychological training program and mental training of the basketball club athletes for better achievement. Received: February, 26, 2021 Accepted: March 13, 2021 Published: March 19, 2021.
Abstract
The purpose of the study. This study aims to determine how high the level of training motivation of athletes when carrying out training. The background of this research is [...]
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FIBRE4YARDS: Visión general del Proyecto
X. Martinez, D. Sá, A. Jurado Fuentes, D. Behrendt

This presentation was made on 15th of April 2021 at the B2B event "Industria náutica".

Abstract
The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced. This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.
Abstract
The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept [...]
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Epidemiological study of human rabies cases in Bangladesh through verbal autopsy
S. Ghosh

(2021).

Abstract
Identiﬁcation of risk factors is crucial to ﬁnd ways to reduce rabies deaths. We investigated the hospital records of rabies deceased through contact tracing of the relatives of the victims using enhanced verbal autopsies (VA) to identify why the people had to die from rabies in recent years in Bangladesh. Patients whose deaths were conﬁrmed by physicians based on the history of animal exposure and clinical signs were taken into account for VA. Socio-demographic proﬁle of the deceased, animal exposure, nature of the wound, and history of postexposure prophylaxis (PEP) data were obtained and analysed. The study found 256 cases in which the cause of death was attributed to rabies, most of the victims were male (71.88%), resided in the rural community (80.47%), dependent (49.22%), and children below the age of 15 years (47.27%). Dogs were the single most responsible (81.64%); however, cats (12.11%), jackals (3.91%) and mongoose (2.34%) were also found accountable for rabies incidence (P< 0.05). Signiﬁcantly, limbs were the most common (67.97%) site of exposure, and the shortest incubation period was identiﬁed in the case of bites to head and face (P < 0.05). The majority (86.72%) of the deceased did not receive any PEP; whereas, 66.80% sought treatment from traditional healers. Among the deceased (13.28%, n¼ 34) who had received PEP, only 8.82% of them completed the full course of the vaccination regimen (P< 0.01); however, none of them had history of taking rabies immunoglobulin (RIG). The study recommends extensive public health awareness programs in the rural community and establishing methods to improve healthcare-seeking behaviours, including receiving PEP instead of visiting traditional healers. Moreover, the availability and accessibility of PEP in the government hospital facilities are desirable, and laboratory-based surveillance with compatible rapid data reporting may be incorporated in the existing policy.
Abstract
Identiﬁcation of risk factors is crucial to ﬁnd ways to reduce rabies deaths. We investigated the hospital records of rabies deceased through contact tracing of the relatives [...]
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Socio-Economic Burden of Tuberculosis among Hospitalized Patients in Dhaka City, Bangladesh
M. Khanom, S. Ghosh

(2021).

Abstract
Tuberculosis (TB) affects the most productive age group people, resulting in economic loss to the individual and their family, particularly in developing countries. This study aimed to assess the economic burden of TB in Hospitalized patients. We conducted a cross-sectional survey among hospitalized TB patients who visited the National Institute of Chest Disease and Hospital, Dhaka, Bangladesh from June 2017 through February 2018. Most TB patients were male (95%) with the age group between 36 and 50 years (42.3%). A majority of the patients (96%) came to the hospital for retreatment of TB. Two-third of the patients went to the hospital from rural areas. The average cost for treating individual TB patients was ~600 US$ (United States dollar). The average productive days lost of a TB patient were 141 days. TB patients from rural areas spent more money than patients living in urban and semi-urban areas. More awareness is needed, particularly in rural people about the current TB burden, nearest TB treatment facilities, and the National Tuberculosis Control Program to minimize economic loss. These study findings also demand the establishment of a specialized TB hospital at the sub-district level.
Abstract
Tuberculosis (TB) affects the most productive age group people, resulting in economic loss to the individual and their family, particularly in developing countries. This study [...]
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Antibiotic Use Among Children Under 5 Years of Age in a Tertiary Care Hospital, Bangladesh
R. Sarker, M. Khan, M. Tareq, S. Ghosh, S. Chowdhury, S. Ghosh

(2021).

Abstract
Antimicrobial resistance is common in low-middle-income countries caused by inappropriate and irrational use of antibiotics in humans and animals. Bangladesh has very limited information on antibiotic use and associated resistance. This study explored the prescribing pattern of antibiotics uses among children visiting a tertiary care hospital in Bangladesh. We conducted a crosssectional study among 400 hospitalized children less than 5 years of age from February to April, 2019, in a tertiary hospital in Bangladesh. Among the 400 children, >50% belonged to the age group for less than 1 year and >60% were male. The average hospital stay period was 3 days (range 1–14 days). The majority of the children had a history of respiratory illnesses (32.2%) and 31% had diarrhea. Most of the children (81.7%) were prescribed one or more antibiotics. The average number of antibiotics per child was 1.17. A combined form of antibiotics was prescribed in 17.43% of children. A total of 14 different antibiotics were prescribed. The most common antibiotic was ceftriaxone (62.39%), followed by azithromycin (18.65%). The parental route was mostly preferred (74.92%) for antibiotic administration. The antibiotic prescription was common in children less than 5 years of age visiting a tertiary level hospital. Most of the prescribed antibiotics were broad spectrum that can promote bacterial resistance. The study’s finding is useful to draw attention to the public health policymakers for taking necessary actions on the appropriate use of antibiotics among children in Bangladesh.
Abstract
Antimicrobial resistance is common in low-middle-income countries caused by inappropriate and irrational use of antibiotics in humans and animals. Bangladesh has very limited [...]
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Prevalence and antimicrobial susceptibility profiles of nontyphoidal Salmonella isolated from chickens in Rajshahi, Bangladesh
B. Sarker, |. Ghosh, |. Chowdhury, |. Dutta, . |, S. Ghosh

(2021).

Abstract
Salmonellosis in poultry is an important disease that seriously impedes the development of the poultry industry. The increased resistance to antimicrobials against Salmonella has been a major public health concern worldwide. We conducted a study from January to June 2016 in and around the Rajshahi district of Bangladesh on the commercial chicken to isolate, identify and characterize poultryspecific Salmonella, to assess the potential risk factors and to determine the antimicrobial resistance pattern of the isolates. The overall prevalence of Salmonella enterica was 41% (49/120) [95% CI: 31.95%– 50.17%] with 41.7% in broiler chicken (25/60) [95% CI: 29.06%– 55.12%] and 40% in layer chicken
Abstract
Salmonellosis in poultry is an important disease that seriously impedes the development of the poultry industry. The increased resistance to antimicrobials against Salmonella [...]
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Major zoonotic diseases of public health importance in Bangladesh
S. Chowdhury, |. Aleem, |. Khan, . |, S. Ghosh

(2021).

Abstract
Zoonotic diseases cause repeated outbreaks in humans globally. The majority of emerging infections in humans are zoonotic. COVID19 is an ideal example of a recently identified emerging zoonotic disease, causing a global pandemic. Anthropogenic factors such as modernisation of agriculture and livestock farming, wildlife hunting, the destruction of wild animal habitats, mixing wild and domestic animals, wildlife trading, changing food habits and urbanisation could drive the emergence of zoonotic diseases in humans. Since 2001, Bangladesh has been reporting many emerging zoonotic disease outbreaks such as nipah, highly pathogenic avian influenza, pandemic H1N1, and COVID19. There are many other potential zoonotic pathogens such as Ebola, Middle East respiratory syndrome coronavirus, Kyasanur forest disease virus and Crimean– Congo haemorrhagic fever that may emerge in the future. However, we have a limited understanding of zoonotic diseases’ overall risk in humans and associated factors that drive the emergence of zoonotic pathogens. This narrative review summarised the major emerging, reemerging, neglected and other potential zoonotic diseases in Bangladesh and their associated risk factors. Nipah virus and Bacillus anthracis caused repeated outbreaks in humans. More than 300 human cases with Nipah virus infection were reported since the first outbreak in 2001. The highly pathogenic avian influenza virus (H5N1) caused more than 550 outbreaks in poultry, and eight human cases were reported so far since 2007. People of Bangladesh are frequently exposed to zoonotic pathogens due to close interaction with domestic and peridomestic animals. The rapidly changing intensified animal– human– ecosystem interfaces and risky practices increase the risk of zoonotic disease transmission. The narrative review's findings are useful to draw attention to the risk and emergence of zoonotic diseases to public health policymakers in Bangladesh and the application of onehealth approach to address this public health threat. We conducted a narrative review of the published literature with a focus on zoonotic diseases reported from Bangladesh. Relevant research articles, review articles, abstracts, case reports, communications, letters, book chapters, conference proceedings and other relevant documents were searched in MEDLINE, PubMed, PubMed Central and Google Scholar. Specific
Abstract
Zoonotic diseases cause repeated outbreaks in humans globally. The majority of emerging infections in humans are zoonotic. COVID19 is an ideal example of a recently identified [...]
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Purposeful Marketing Model in Companies Providing Internet of Things Products based on Grounded Theory Approach
H. Teimouri, J. gharibi, A. Hosseinzadeh, A. Pooya

Collection of European Research on Management and Business Economics (2021). 1

Abstract
'''Background''': The objective of this study is to design an purposeful marketing model based on customer clustering of companies active in the field of internet of tings industry with the grounded theory approach of the Strauss and Corbin. According to the systematic model of the grounded theory approach, 75 experts with knowledge of the research topic and related work experience were identified and selected for the statistical population. '''Methodology''': Using purposeful nonprobability sampling and snowball method, 19 people were interviewed semi-structured and in-depth as a research sample, which resulted in five stages of data adequacy. Then, the data were analyzed by MAXQDA 2018 software. To evaluate the obtained model, structural equation modeling technique with partial least squares method (PLS-SEM) and Smart PLS software was used. The GOF model was used for overall evaluation of fit index. '''Findings''': A model for purposeful marketing of companies providing internet of things equipment and services was identified. '''Conclusion''': The model obtained by structural equation modeling with partial least squares approach was evaluated by Smart PLS software, which showed that the model fits well. Therefore, the discovered model was approved and the results obtained from it, showed the importance of various variables role. These variables including market orientation, intensity of competitive environment, emergence of technological innovations and the existence of resource constraints in these companies as excellent conditions as well as company's organizational characteristics variables. Company's management characteristics are considered as the intervening conditions as well as the characteristics of internet of things equipment and services, the characteristics of internet of things users / customers and the preferences and benefits expected by internet of things users / customers as the underlying conditions. It should be noted that paying attention to them and the use of user / customer clustering strategy will have consequences such as optimal management of organizational resources, optimal management of user / customer preferences, optimal management of user / customer relationships and increase of organizational productivity for companies active in the field of internet of things.
Abstract
'''Background''': The objective of this study is to design an purposeful marketing model based on customer clustering of companies active in the field [...]
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A Method for Accurate and Efficient Propagation of Satellite Orbits: A Case Study for a Molniya Orbit
R. Flores, M. Burhani, E. Fantino

Alexandria Engineering Journal (2021). Alexandria Engineering Journal (2021) 60, 2661–2676

Abstract
Fast and precise propagation of satellite orbits is required for mission design, orbit determination and payload data analysis. We present a method to improve the computational performance of numerical propagators and simultaneously maintain the accuracy level required by any particular application. This is achieved by determining the positional accuracy needed and the corresponding acceptable error in acceleration on the basis of the mission requirements, removing those perturbation forces whose effect is negligible compared to the accuracy requirement, implementing an efficient and precise algorithm for the harmonic synthesis of the geopotential gradient (i.e., the gravitational acceleration) and adjusting the tolerance of the numerical propagator to achieve the prescribed accuracy level with minimum cost. In particular, to achieve the optimum balance between accuracy and computational performance, the number of geopotential spherical harmonics to retain is adjusted during the integration on the basis of the accuracy requirement. The contribution of high-order harmonics decays rapidly with altitude, so the minimum expansion degree meeting the target accuracy decreases with height. The optimum degree for each altitude is determined by making the truncation error of the harmonic synthesis equal to the admissible acceleration error. This paper presents a detailed description of the technique and test cases highlighting its accuracy and efficiency.
Abstract
Fast and precise propagation of satellite orbits is required for mission design, orbit determination and payload data analysis. We present a method to improve the computational [...]
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BEHAVIOUR OF A CRACKED GAS PIPELINE
J. Massa, A. Giudici

Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil (2009). Rev. Int. de Desastres Naturales, Accidentes e Infraestructura Civil. Vol. 9(1-2)

Abstract
When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered. In order to minimize potential hazards, this subject is treated in international regulations. Manufacturing characteristics of gas pipes and their typical defects are described in the first part of this work. Safety concerns related to the presence of real and potential crack type defects in gas pipes are presented. An actual gas pipeline, which has been feeding natural gas to the city of Córdoba (Argentina) for more than forty years, is considered as a study case. In order to determine the properties of this gas pipeline, mechanical tests from material samples were carried out. The stress state associated with “plane” type defects is determined using a model that is based on the material toughness of the pipe, which is appropriate for studying the behavior of cracks. This model allows computing, depending on the dimensions of the pipe, the transition pressure which separates possible defects into two categories: defects which cause failure by breakage of the pipe and defects which only cause gas leaks. The pipe failure pressure for passing and non-passing defects can also be determined using this model. The system safety conditions are defined considering the size of the defects and the work pressure. The range of lengths of possible defects, the size of the defects that are critical, and the size of the defects which are tolerable for a fixed safety coefficient, are determined. Finally, the problem of determining in a quick way, the reduced pressure acceptable for the safe operation until repairs, of a system under the presence of a crack of “non-tolerable size”, is addressed.
Abstract
When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered. In order to minimize potential hazards, this subject is [...]
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DAMAGE BY CORROSION IN PIPELINES
J. Massa, A. Giudici

Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil (2010). Rev. Int. de Desastres Naturales, Accidentes e Infraestructura Civil. Vol. 10(2)

Abstract
When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered. In order to minimize potential hazards, this subject is treated in international regulations. Safety concerns related to the presence of real and potential corrosion type defects in gas pipes are presented. An actual gas pipeline, which has been feeding natural gas to the city of Córdoba (Argentina) for more than forty years, is considered as a study case. In order to determine the properties of this gas pipeline, mechanical tests from material samples were carried out. The stress state associated with “volumetric” type defects is determined using a model that is based on the flux stress of the material of the pipe, which is appropriate for studying the behavior of corroded pipelines. This model allows computing, depending on the dimensions of the pipe and the length of the defect, the transition pressure which separates possible defects into two categories: those which cause failure by breakage of the pipe and those which only cause gas leaks. The pipe failure pressure for passing and non-passing defects can also be determined using this model. The system safety conditions are defined considering the size of the defects and the work pressure. The range of lengths of possible defects, the size of the defects that are critical, and the size of the defects which are tolerable for a fixed safety coefficient, are determined. Finally, the problem of determining in a quick way, the reduced pressure acceptable for the safe operation until repairs, of a system under the presence of flaws of “non-tolerable size”, is addressed.
Abstract
When designing systems for the transportation and distribution of gas, safety is one of the main issues to be considered. In order to minimize potential hazards, this [...]
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Effect of Covid-19 Pandemic in Construction Labor Productivity: A Quantitative and Qualitative Data Analysis
E. Quezon, A. Ibanez

American Journal of Civil Engineering and Architecture (2021). vol. 9, no. 1 (2021): 23-33. doi: 10.12691/ajcea-9-1-4.

Abstract
This research aims to identify and analyze the various factors affecting construction labor productivity covering the period from December 9, 2020, to January 31, 2021, a year after it was declared Covid-19 a pandemic. Due to the pandemic effect, the local government units in four selected study areas imposed intermittent Enhance Community Quarantine on all places to control the Coronavirus spread in compliance with the health department protocol. Fifty-five questionnaires returned out of 63 distributed are tabulated according to each group-related factor. The correlation analysis resulted in the highest coefficient value of 0.89 between the CTDEO and contractor groups. Meaning, most respondents have the same perception of the factors affecting construction's low labor productivity. Besides, results depicted that the absence of health workers on the construction site ranked 1st in the health & safety provision factor group with an RII of 0.97, followed by no safety engineers on the construction project sites with an RII of 0.93. From all the seven groups of factors, the health and safety group-related factors ranked 1st with an RII of 0.81, next, the schedule compression group with an RII of 0.78. Hypothesis testing asserted that working six days per week was one of the significant factors affecting labor productivity on the contractor's side, suggested by more than 50% of the respondents. The workforce group-related factors with an RII of 0.77 demonstrated a slight difference with the schedule compression group-related factors. Thus, the Covid-19 pandemic has a significant effect on the essential factors affecting construction's low labor productivity.
Abstract
This research aims to identify and analyze the various factors affecting construction labor productivity covering the period from December 9, 2020, to January 31, 2021, [...]
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Accurate Timoshenko beam elements for linear elastostatics and LPB stability
C. Felippa, E. Oñate

Archives of Computational Methods in Engineering (2021). Vol. 28(3), pp. 2021-2081

Abstract
Several methods to derive accurate Timoshenko beam finite elements are presented and compared. Two application problems are examined: linear elastostatics and linearized prebuckling (LPB) stability analysis. Accurate elements can be derived for both problems using a well known technique that long preceeds the Finite Element Method: using homogeneous solutions of the governing equations as shape functions. An interesting question is: can accurate elements be derived with simpler assumptions? In particular, can linear-linear interpolation of displacements and rotations with one-point integration reproduce those elements? The answers are: no if standard variational tools based on classical functionals are used, but yes if modified functionals are introduced. The connection of modified functionals to newer methods, in particular templates, modified differential equations and Finite Increment Calculus (FIC) are examined. The results brings closure to a 50-year conumdrum centered on this particular finite element model. In addition, the discovery of modified functionals provides motivation for extending these methods to full geometrically nonlinear analysis while still using inexpensive numerical integration.
Abstract
Several methods to derive accurate Timoshenko beam finite elements are presented and compared. Two application problems are examined: linear elastostatics and linearized prebuckling [...]
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Mathematical optimization problems for particle finite element analysis applied to 2D landslide modeling
L. Wang, X. Zhang, F. Zaniboni, E. Oñate, S. Tinti

Mathematical Geosciences (2021). Vol. 53, pp. 81–103

Abstract
Notwithstanding its complexity in terms of numerical implementation and limitations in coping with problems involving extreme deformation, the finite element method (FEM) offers the advantage of solving complicated mathematical problems with diverse boundary conditions. Recently, a version of the particle finite element method (PFEM) was proposed for analyzing large-deformation problems. In this version of the PFEM, the finite element formulation, which was recast as a standard optimization problem and resolved efficiently using advanced optimization engines, was adopted for incremental analysis whilst the idea of particle approaches was employed to tackle mesh issues resulting from the large deformations. In this paper, the numerical implementation of this version of PFEM is detailed, revealing some key numerical aspects that are distinct from the conventional FEM, such as the solution strategy, imposition of displacement boundary conditions, and treatment of contacts. Additionally, the correctness and robustness of this version of PFEM in conducting failure and post-failure analyses of landslides are demonstrated via a stability analysis of a typical slope and a case study on the 2008 Tangjiashan landslide, China. Comparative studies between the results of the PFEM simulations and available data are performed qualitatively as well as quantitatively.
Abstract
Notwithstanding its complexity in terms of numerical implementation and limitations in coping with problems involving extreme deformation, the finite element method (FEM) [...]
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A nodal-integration based particle finite element method (N-PFEM) to model cliff recession
J. Meng, X. Zhang, S. Utili, E. Oñate

Geomorphology (2021). Vol. 381, pp. 107666

Abstract
Cliff recession poses a significant threat to the built environment, transportation infrastructure and land use. In this paper, a novel computational framework called the Nodal-integration based Particle Finite Element Method (N-PFEM) is developed for modelling the cliff recession resulting from weathering-induced landslides. The N-PFEM combines the nodal-integration technique with the PFEM in second-order cone programming and thus requires no variable mapping operation, which is essential in the classical PFEM for modelling history-dependent materials, for modelling large deformation problems such as landslides in cliff recession processes. To verify the developed N-PFEM, a series of benchmarks have been simulated including the cliff recession under both the weathering-limited and transport-limited conditions. Simulation results from the N-PFEM are validated in detail to these from the limit analysis method, well established geomorphologic models and the discrete element method. Additionally, measures for preventing cliff recession such as the construction of retaining wall structures are also investigated using the N-PFEM.
Abstract
Cliff recession poses a significant threat to the built environment, transportation infrastructure and land use. In this paper, a novel computational framework called the [...]
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A review of graphene reinforced Cu matrix composites for thermal management of smart electronics
S. Ali, F. Ahmad, P. Yusoff, N. Muhamad, E. Oñate, M. Raza, K. Malik

Composites Part A: Applied Science and Manufacturing (2021). Vol. 144, pp. 106357

Abstract
Heat dissipation remains a key challenge to be addressed, determining the performance and durability of smart electronic devices. Graphene reinforced metal matrix composites have been extensively studied as a thermal management material due to their high thermal conductivity and low coefficient of thermal expansion. The emphasis of this review is pivoted on the thermal conductivity enhancement of graphene reinforced Cu matrix composites developed in the recent literature. An overview of factors affecting thermal conductivity of composite namely defect processing route, density, graphene derivative, lateral size, concentration, alignment, graphene/matrix interfacial bonding and graphene modification are discussed. An extensive weightage is given to the processing route as it is the most influential factor in determining the enhancement efficiency. Furthermore, graphene based functional products such as heat spreader and heat sink developed for heat dissipation of electronic devices are also reviewed. Finally, the development and outlook for graphene based Cu composites are presented.
Abstract
Heat dissipation remains a key challenge to be addressed, determining the performance and durability of smart electronic devices. Graphene reinforced metal matrix composites [...]
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Methodological-technological framework for construction 4.0
F. Muñoz, J. Mora-Serrano, I. Valero, E. Oñate

Archives of Computational Methods in Engineering (2021). Vol. 28, pp. 689–711

Abstract
The construction industry has traditionally been characterised by the high diversity of its agents and processes, high resistance to change and low incorporation of technology compared to manufacturing industries. However, the construction sector is experiencing now a strong renovation process in methodology and tools due to the incorporation of the Building Information Modelling, Lean Construction and Integrated Project Delivery. Meanwhile, in production systems, “Industry 4.0” is a new paradigm that proposes automation, monitoring, sensorisation, robotisation, and digitalisation to improve production and distribution processes. In this context, some authors have proposed the concept of “Construction 4.0” as the counterpart of Industry 4.0 for the construction sector, although the methodological-technological implications are not clear. This research shows a methodological-technological framework adapted to the Architecture, Engineering, Construction, and Operations industry. This papers includes a detailed proposal for a reference frameworks and related technologies that could impact on this sector, responding to its complexities and specific challenges, such as the unique spaces for each work, which are difficult to standardise, arbitrary cost overruns and a productivity far below the average for other industries, increasing competitiveness and globalisation, as opposed to its traditionally local deployment, and an increasing demand to reduce the carbon footprint for all its activities.
Abstract
The construction industry has traditionally been characterised by the high diversity of its agents and processes, high resistance to change and low incorporation of technology [...]
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Evaluation of the HMA performance using combined effects of marble waste dust filler and superpave aggregate gradation
A. Mulatu, E. Quezon, O. Gudina

Australian Journal of Civil Engineering (Select a year). Adamu Mulatu , Emer Tucay Quezon & Oluma Gudina (2020): Evaluation of the HMA performance using combined effects of marble waste dust filler and superpave aggregate gradation, Australian Journal of Civil Engineering. 12(1); 1-11, Doi: 10.1080/14488353.2020.1854942

Abstract
During the fabrication of new products, a variety of wastes discharged and stored by causing harsh environmental problems. The marble processing plant is amongst the industrial sector that produces huge waste. Thus, the main purpose of this study is to evaluate the combined effects of marble waste dust filler and Superpave aggregate gradation on the performance of HMA. Based on the Marshall Mix design, seventy-two (72) specimens were produced from three below-restricted zones (BRZ) of Superpave gradation (BRZ4, BRZ5, & BRZ6) by using the 0.45 power chart. The design gradation obtained to be BRZ5 with 4.96% OBC with corresponding values 9.13 KN of stability, 2.96 mm of flow, 73.51% of VFA, 15.73% of VMA, 2.308 gm/cm3, of bulk density, and 4% of air void. The crushed stone dust filler was partially replaced by Marble Waste Dust filler (under No. 200 sieve) at a replacement rate of (1%, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5%) by keeping design gradation and OBC constant. The test showed satisfactory results. The Marshall mix design parameters of all mixtures are within the specification limit under international and local specifications. Marble waste dust filler when blended with a BRZ of Superpave gradation indicated a substantial effect on Marshall stability with 10.18 KN value at 3% MWD filler content.
Abstract
During the fabrication of new products, a variety of wastes discharged and stored by causing harsh environmental problems. The marble processing plant is amongst the industrial [...]
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Evaluation of waste engine oil rejuvenation for highly short term aged asphalt binder
B. Tadele, E. Quezon

Australian Journal of Civil Engineering (2021). Biruk Tadele & Emer Tucay Quezon (2021): Evaluation of waste engine oil rejuvenation for highly short term aged asphalt binder, Australian Journal of Civil Engineering, DOI: 10.1080/14488353.2021.1896124

Abstract
The aging property of the asphalt binder is time-dependent. A time-dependent short-term aging property of 80/100 penetration grade bitumen and the possibility of waste engine oil rejuvenation for the highly aged asphalt binder performance were investigated. Four specimens of equal weight from the penetration grade-80/100 bitumen are collected. The first specimen was checked for quality requirements. The other three specimens were aged using a rolling thin film oven for 85, 115, and 145 minutes to simulate the delay during hot mix asphalt production, hauling, and compaction. The highly aged bitumen was rejuvenated with 2%, 5%, and 10% Waste Engine Oil by weight. Results indicated that as the aging time increased, penetration and ductility decreased, softening point, flash point, fire point, and mass loss increased. A conventional test showed that highly aged bitumen from the trial period was 145 minutes and 10% waste engine oil obtained the optimum dosage. Further, multiple stress creeps recovery analyses indicated the rejuvenated binder is prone to pavement rutting above 70°C, and rejuvenation is effective for pavement temperature below 70°C. Hence, exposing the asphalt binder for temperature for a more extended period affects pavement performance.
Abstract
The aging property of the asphalt binder is time-dependent. A time-dependent short-term aging property of 80/100 penetration grade bitumen and the possibility of waste engine [...]
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Statistical Analysis on Shear Strength Parameter from Index Properties of Fine-grained Soils
T. Bakala, E. Quezon, M. Yasin, S. contributions

Journal of Engineering Research and Reports (2021). Tariku Tafari Bakala, Emer Tucay Quezon and Mohammed Yasin. Statistical Analysis on Shear Strength Parameter from Index Properties of Fine-grained Soils. Journal of Engineering Research and Reports. 2021; 20(4): 15-28. DOI: 10.9734/JERR/2021/v20i417291

Abstract
Shear strength is the essential engineering property of soil required to analyze and design foundations, retaining walls, bridges, embankment, and related infrastructure. The laboratory equipment and field instruments are not sufficient in developing countries to obtain soil engineering properties, especially strength properties. Thus, Geotechnical engineers usually endeavor to develop statistical models that best fit a particular area and soil type, especially for analysis and design purposes. In this research, a Statistical Analysis on the Shear Strength parameter from the Index Properties of Fine-Grained Soils was studied. For predicting the undrained shear strength parameter, single linear regression (SLR) and multiple linear regressions (MLR) analyses were developed. To develop the intended statistical models for a study, SAS JMP Pro 13, SPSS v22, and Microsoft Excel-2013 software were introduced. The results of a study indicated that undrained shear strength(Cu) was significantly correlated with liquid limit(LL), plastic limit(PL), bulk density (ρbulk), dry density(ρdry), natural moisture content(NMC), and plasticity index(PI). While it was not significantly correlated with a specific gravity (Gs) and liquidity index (LI) of study area soil. Finally, a strong Model of Cu with a coefficient of determination (R2 = 0.806), good significance level, and less Std. error was obtained from multiple linear regression (MLR) analysis. The developed model can figure undrained shear strength parameter and wide application in the construction industry to minimize the cost, effort, and time for laboratory tests of shear strength parameter of a study area.
Abstract
Shear strength is the essential engineering property of soil required to analyze and design foundations, retaining walls, bridges, embankment, and related infrastructure. [...]
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Model-Based Urban Road Network Performance Measurement Using Travel Time Reliability: A Case Study of Addis Ababa City, Ethiopia
S. Assen, E. Quezon

American Journal of Civil Engineering and Architecture (2019). Seada Mohammed Assen, and Emer Tucay Quezon, “Model-Based Urban Road Network Performance Measurement Using Travel Time Reliability: A Case Study of Addis Ababa City, Ethiopia.” American Journal of Civil Engineering and Architecture, vol. 7, no. 5 (2019): 202-207. doi: 10.12691/ajcea-7-5-2.

Abstract
In heterogeneous traffic conditions, the performance of the road network is described by vehicles and driver characteristics. Nowadays, traffic congestion, delay, and unreliability are terms that are most associated with present-day travel, in which transport users spend their precious time on long traffic queues. Due to this, late arrival at the workplace and appointment for social or business activities have become a perennial problem in the study area. In addition, during traffic queues, vehicle fuel emission increases in congested traffic segments affecting the environment, particularly the issue of global warming. This research study evaluated the performance of the road network in terms of travel time reliability in order to determine the main factors affecting travel time reliability. Ten road segments were selected to analyze the performance level and efficiency of the road network, considering the travel time probability distribution, and reliability of road segments in Addis Ababa City. From these road segments, nine were selected to formulate the model, and one road segment considered for validation of the result. The reliability of the road segments was analyzed using travel time reliability measures such as buffer time, buffer time index, planning time index, and the travel time index. It was used a multiple linear regression model to predict the travel time reliability of the road segments with R2
Abstract
In heterogeneous traffic conditions, the performance of the road network is described by vehicles and driver characteristics. Nowadays, traffic congestion, delay, and unreliability [...]
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Performance Evaluation of Grade Separation Within the Selected Major Intersection in Addis Ababa City
S. Leleisa, E. Quezon, T. Wedajo

American Journal of Traffic and Transportation Engineering (2018). Sentayehu Leleisa, Emer Tucay Quezon, Teyba Wedajo. Performance Evaluation of Grade Separation Within the Selected Major Intersection in Addis Ababa City. American Journal of Traffic and Transportation Engineering. Vol. 3, No. 3, 2018, pp. 41-49. doi: 10.11648/j.ajtte.20180303.11

Abstract
Urban City Traffic Management introduced various remedies to decongest traffic and to reduce the severity of accidents, such as providing traffic signal controls at the intersecting roads at different levels, or grade separating the traffic movement towards different directions. One type of grade separation is Road Underpass or Flyover. The construction of Road Underpass or Flyover poses some doubts whether it is effective or ineffective from the point of view of the travelers or motorists. It is for this reason that this research sought to evaluate the performance and effectiveness of the Road Underpass structure on traffic flow at the major intersection, specifically the Wellosefer intersection in Addis Ababa City. The primary data used the existing traffic volume recorded between 7:00 AM – 6:00 PM from Monday to Friday. While the secondary data obtained from the Consulting Office 'before' the improvement of Wellosefer intersection, including the previous study, which served as the control analysis for the research. From these data, the analyses provided results on vehicle travel time and delay for a case 'before' and 'after' improvement of the intersection. SIDRA Software was used to analyze the traffic conditions of the intersection. Based on the findings of the study, a case 'before' Improvement of Wellosefer Unsignalized T-Intersection indicated an average delay of vehicles of about 535.7 seconds and a travel time of vehicles of about 574.7 seconds. On the other hand, in a case 'after' Improvement of Wellosefer intersection, three alternatives considered; such as 1) Signalized T-Intersection, 2) Roundabout and 3) Road Underpass with Roundabout at the upper level. The results of the first alternative showed the Signalized T-intersection indicated an average delay and travel time of 344.3 seconds and 365.0 seconds, respectively. It means, there could be a reduction of 15.4% in average delay if signalized intersection implemented. The second alternative, a case of Roundabout using the same traffic data at current condition, the results indicated the motorists and commuters would be experiencing an average delay of about 355.8 seconds and average travel time of 390.0 seconds. The third alternative considering Road Underpass with Roundabout at the upper level, the results revealed that there was a significant reduction in an average delay of vehicles of about 42% from the Unsignalized T-Intersection. Comparing this result with the Signalized intersection using the same traffic data, showed that there was a significant decrease in average delay. Therefore, the findings of the study, a combination of Road Underpass and Roundabout at the upper level as in the case of Wellosefer intersection performed well than the other traffic control design alternatives.
Abstract
Urban City Traffic Management introduced various remedies to decongest traffic and to reduce the severity of accidents, such as providing traffic signal controls at the intersecting [...]
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Traffic Safety Evaluation at Unsignalized road Intersection using Proactive Approach
. Abstract, E. Quezon

Proceedings of the 2nd Annual Ethiopian Road Safety (RSC2018) (2018). Seifeddin Haji, Prof. Emer T. Quezon, Murad Mohammed, Biruk Yigezu. Traffic Safety Evaluation on Urban Road Un-signalized Intersection using Proactive Approach: A Case Study in Adama City. Proceedings of the 2nd Annual Ethiopian Road Safety (RSC2018) Addis Ababa, Ethiopia, August 23-24, 2018

Abstract
Deaths and injuries as a result of road accidents are a recognized global problem and authorities are aware of the consequences this global phenomenon might lead to. Because of the rapid development of urbanization and motorization in developing and transitional countries, like Ethiopia, actions to improve traffic safety conditions are urgently needed. Highway intersections are among the greatest safety challenges because they are some of the most common highway features. Improving the safety level of the urban intersection is an important way to increase safety. Safety evaluations can help to develop effective safety countermeasures to lower crash rates and reduce crash severity. So how to diagnose safety problems and improve urban road intersection safety effectively becomes an important issue. Now, there have been quite a number of safety analysis methods and theories in the city intersection, but these methods and theories are formed on the basis of traffic accidents. However, the data on traffic accidents is not accurate enough, these theories are not appropriate for our country. Also, it is impractical and unethical to wait for accidents to occur before being able to draw statistically sound conclusions regarding safety improvement. Hence there is a need to develop a proactive approach, a non-accident-based approach, to evaluate urban road Unsignalized intersection safety performance. A proactive approach (indirect and non-accident based approach) was attempted to that of traditional reactive approach (direct and accident based approach) which is purely based on the existing conditions that have direct relationships or impacts to traffic safety such as the geometric, traffic control & engineering, road Surface and environment characteristics. The non-accident-based approach is based on field surveys under the conditions mentioned previously, summarizes the intersection safety diagnosis in a safety index to indicate the safety performance of the intersection. The study indicates that the proposed methodology and intersection safety diagnosis technique can be used to perform an evaluation of traffic safety and improvement at an intersection even when there are few resources available. Also, the use of intersection safety diagnosis is a more resource-efficient and ethically appealing alternative for fast, reliable, and effective safety assessment.
Abstract
Deaths and injuries as a result of road accidents are a recognized global problem and authorities are aware of the consequences this global phenomenon might lead to. Because [...]
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Investigation of Pedestrian Safety Problems and Its Countermeasures: A Case Study in Nekemte City, Ethiopia
H. Alemgena, P. Quezon, T. Kumela, E. Quezon

International Journal of Engineering and Technical Research (2018). Alemgena, H.; Quezon, ET.; Kumela, T. Investigation of Pedestrian Safety Problems and Its Countermeasures: A Case Study in Nekemte City, Ethiopia. International Journal of Engineering and Technical Research. 2018; 8(2): 58-64

Abstract
The actual growth of urban economic activities and simple movements of peoples and goods measured through its primary transport system. The requirements of the pedestrian should be considered in the design of the urban environment and transportation facilities. Since road infrastructure improvements and designed pedestrian environments are an essential part of road safety enhancements that increase walking and decrease fatalities. This study investigated the pedestrian safety problems and its countermeasures on road segments in Nekemte city. This study examined the existing issues affecting the safety of pedestrian movement, evaluates the service quality of walking facilities, and finally identified the most significant factors affecting pedestrian safety with engineering countermeasures in the city. For the data analysis, the study used both objective measurements and subjective assessments to model PLOS using Australian methods. As per field study indicates 60% of the respondents' think the sidewalk is not user-friendly. In the city, the built road infrastructure is lacking pedestrian facility management and appropriate maintenance activities. Since the walkways in Nekemte city, in general, have almost the same problems like non-continuous, crack, and non-covered utility holes which are difficult especially for pedestrians with disabilities. The current sidewalk is encroached either by vendors, utility poles, parking carts or illegal construction materials in different places, and crosswalk facilities are not visible and not enough provided at a logical distance. The Pedestrian LOS analysis indicates that poor pedestrian conditions exist and the factors that negatively affect pedestrian LOS are wide-ranging in this city road segment. It concluded that Pedestrian facilities and all the concerned factors should be provided and maintained to more efficient for both encouraging people to walk and improve pedestrian safety.
Abstract
The actual growth of urban economic activities and simple movements of peoples and goods measured through its primary transport system. The requirements of the pedestrian [...]
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Analysis of StressStrain and Deflection of Flexible Pavements Using Finite Element Method Case Study on Bako-Nekemte Road
S. Wayessa, E. Quezon, T. Kumela

Journal of Civil, Construction and Environmental Engineering (2017). Shiferaw Garoma Wayessa, Emer Tucay Quezon, Tarekegn Kumela. Analysis of Stress- Strain and Deflection of Flexible Pavements Using Finite Element Method Case Study on Bako-Nekemte Road. Journal of Civil, Construction and Environmental Engineering. Vol. 2, No. 4, 2017, pp. 100-111. doi: 10.11648/j.jccee.20170204.11

Abstract
In Ethiopia, the failure of roads is before the handover period. Most roads found in Ethiopia are flexible pavements. Nowadays, the failure of the surface of flexible pavement roads is common before the expected design period. For example, the Bako-Nekemte road/ has become a critical issue in our country. The most common parameters that cause stress, strain, and deflection of the roads are loads and pressures that come from vehicles. Moreover, the modulus of elasticity, Poisson’s ratio, and thickness of each layer need to be characterized. Further, the load magnitude, contact pressure (or load radius), and location are defined for each load (wheel) considered. The finite element method (FEM) is a numerical analysis technique to obtain the stress-strain and deflection of each pavement layer. The analytical method usually uses layers thickness, loads, elastic modulus, and Poisson’s ratio of the pavement materials as design parameters. The objective of this research was to study the sensitivity of the road parameters in analyzing the major causes of failure in asphalt pavement layers fatigue cracking and rutting deformation which came due to the critical tensile strains at the bottom of the asphalt layer and the critical compressive strains on the top of subgrade using the finite element method by relating the standard specification of ERA and laboratory test result. This thesis studied the analysis of stress-strain and deflection of flexible pavements using the Everstress finite element method. The Ever stress program will take into account any stress-dependent stiffness characteristics. This thesis dealt with ways to reduce deflections by varying the design configuration, such as increasing the HMA modulus, the base modulus, sub-base modulus, the subgrade modulus, and increasing the thickness of each layer. Based on the type of materials to use the value of elastic modulus and poison’s ratio are various in each layer, in layer 1 is varied from 1500 to 3500 MPa, in layer 2 is varied from 200 to 1000MPa, in layer 3 is varied from 100 to 250 MPa and in layer 4 is varied from 20MPa to 150MPa.
Abstract
In Ethiopia, the failure of roads is before the handover period. Most roads found in Ethiopia are flexible pavements. Nowadays, the failure of the surface of flexible pavement [...]
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Efficiency Assessment of the Complex Process of Variable Cutting Parameters
M. Jia, Y. Su, Z. Zuo, Y. Zhan*, Y. Xu, D. Xiang, . Diamond20210

Diamond20210's personal collection (2021). 1

Abstract
Saving energy and low carbon strategy has becoming the future trend of manufacturing industry. Cutting process in mechanical manufacturing has the characteristics of heavy energy consumption and complex process. The estimation and evaluation of energy consumption and energy efficiency of cutting process are hot topics in research groups and industry. The energy consumption of cutting process is determined by the load, which is related to the cutting parameters under fixed cutting systems, while the cutting parameter might change with the cutting process and material. Based on the relationship between energy consumption and cutting characteristics and the quality requirements, the cutting specific energy u(t) = P(t)/M(t), which is varies with time is proposed to evaluate the energy consumption of various cutting parameters under complex machining processes. The influence of cutting parameters on cutting energy consumption is studied by experiments and a calculation method is proposed to calculate cutting energy consumption. Finally, a case study of complex curve machining in mold manufacturing is illustrated to prove the effectiveness of the proposed evaluation method.
Abstract
Saving energy and low carbon strategy has becoming the future trend of manufacturing industry. Cutting process in mechanical manufacturing has the characteristics of heavy [...]
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Offshore Oil and Gas Safety: Protection against Explosions
D. Brkić, Z. Stajić

Journal of Marine Science and Engineering (2021). 9(3), article 331.

Abstract
Offshore oil and gas operations carry a high risk of explosions, which can be efficiently prevented in many cases. The two most used approaches for prevention are: (1) the “International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres” (IECEx) and (2) European “Atmosphere Explosible” (ATEX) schemes. The main shortcoming for the IECEx scheme is in the fact that it does not cover nonelectrical equipment, while for the ATEX scheme, it is due to the allowed self-certification for a certain category of equipment in areas with a low probability of explosions, as well as the fact that it explicitly excludes mobile offshore drilling units from its scope. An advantage of the IECEx scheme is that it is prescribed by the US Coast Guard for protection against explosions on foreign mobile offshore drilling units, which intend to work on the US continental shelf but have never operated there before, with an additional requirement that the certificates should be obtained through a US-based Certified Body (ExCB). Therefore, to avoid bureaucratic obstacles and to be allowed to operate with minimized additional costs both in the US and the EU/EEA’s offshore jurisdictions (and very possibly worldwide), all mobile offshore drilling units should be certified preferably as required by the US Coast Guard.
Abstract
Offshore oil and gas operations carry a high risk of explosions, which can be efficiently prevented in many cases. The two most used approaches for prevention are: (1) the [...]
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Simplified Indirect Estimation of Pump Flow Discharge: An Example from Serbia
M. Amon, M. Radić, Z. Stajić, D. Brkić, P. Praks

Water (2021). 13(6), article 796.

Abstract
In the absence of a flowmeter or due to its inaccuracy, the flow rate at the discharge section of the pipeline following the observed pump can be roughly estimated if the pressure can be measured instead. To use the proposed procedure two main conditions should be achieved: (1) a manometer should be installed at the discharge pipeline between the pump and the flow regulation valve, and (2) the actual curve that relates pressure and flow for the observed pump unit should be known in advance. The described example is from Serbia, but it is of interest for any water pumping station with a submersible pump (installed in wells or tanks) where a limited number of adequate places for the measuring of flow are available (if any are available at all), but where the pressure at the discharge pipe of the observed pump can be measured. This simplified method can find applicability in installations in remote rural regions where limited resources are available. The results show that the calculated values of the flow obtained by the presented method deviate greatly in relation to the measured values provided by the portable ultrasonic flowmeter, up to 60% at one of the measuring points. However, in relation to the measured values provided by the permanently installed flowmeter the discrepancy is significantly lower (0.6–6.8%).
Abstract
In the absence of a flowmeter or due to its inaccuracy, the flow rate at the discharge section of the pipeline following the observed pump can be roughly estimated if the [...]
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Calcined Termite Hill Clay Powder: As Partial Cement Replacement in Production of C-25 Grade Concrete
G. Danbala, E. Quezon, G. Kebede

American Journal of Civil Engineering and Architecture (2019). Guyo Konso Danbala, Emer Tucay Quezon, and Getachew Kebede, “Calcined Termite Hill Clay Powder: As Partial Cement Replacement in Production of C-25 Grade Concrete.” American Journal of Civil Engineering and Architecture, vol. 7, no. 3 (2019): 128-134. doi: 10.12691/ajcea-7-3-2.

Abstract
Cement is one of the components of concrete plays a great role in the construction industry. Nevertheless, it is the most expensive and environmentally unfriendly material. Therefore, requirements for economical and more environmentally-friendly cementing materials have extended interest in other cementing materials that can be used as partial replacement of the ordinary Portland cement. This research was, conducted to examine the suitability of calcined termite hill clay powder as a cement replacing material in the production of C-25 grade concrete as a relief for this problem. The Termite Hill Clay sample was collected from Bokuluboma vicinity. The sample was calcined at the temperature of 650°C using muffle furnace, ground to the fineness of 150 µm and its chemical composition was investigated. Normal consistency and setting time of the paste having Ordinary Portland Cement and calcined termite hill clay powder from 0% to 40% replacement in 5% increment percentage investigated. The compressive strength of eight different concrete mixes with the CTHCP replacing the ordinary Portland cement prepared for 22MPa and 34MPa (i.e., for 7th and 28th days targeted compressive strength) concrete with water cement ratio of 0.5 and 360kg/m3 cement content. The properties of the mixture assessed both at the fresh and hardened state. Results revealed that calcined termite hill clay powder found pozzolanic and can partially replace cement. It has shown that up to 11.3% replacement of the ordinary Portland cement by CTHCP, the cubes achieved a target mean compressive strength of C-25 grade concrete at 28th day 34Mpa. Although, the replacement percentage greater than 11.3% of the cement of calcined termite hill clay powder in the concrete has shown a slightly lower compressive strength. Moreover, the mix indicated workable up to 25% replacement percentage and also the setting time of the paste containing calcined termite hill clay powder found faster than that of the control mix. Hence, it is concluded that CTHCP was suitable to replace cement partially with 11.3% replacement of cement by calcined termite hill clay powder as the optimal percentage of the production of C-25 grade concrete. The fresh concrete mix was workable up to 25% replacement, and the mineral admixture served as an accelerator which is suitable for cold weather concreting works.
Abstract
Cement is one of the components of concrete plays a great role in the construction industry. Nevertheless, it is the most expensive and environmentally unfriendly material. [...]
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Evaluation of the Performance of Brick Dust as a Filler Material for Hot Asphalt Mix Design A Case Study in Jimma Zone
F. Wagaw, P. Quezon, A. Geremew, E. Quezon

The International Journal of Engineering and Science (2018). Fisseha Wagaw, Prof. Emer Tucay Quezon, Anteneh Geremew. Evaluation of the Performance of Brick Dust as a Filler Material for Hot Asphalt Mix Design: A Case Study in Jimma Zone. The International Journal of Engineering and Science. 2018; 7(3): 64-72. DOI:10.9790/1813-0703026472

Abstract
A bituminous paving mixture is a mixture of coarse aggregate, fine aggregate, and bitumen mixed in suitable proportion to result in a strong and durable mix in order to withstand traffic load. In this paving mix, ordinary stone dust, and cement used as filler material. One of the main problems in the construction of a bituminous paving mixture is the insufficient amount of filler from crushing stone aggregate, and cement supply is low. A study has been carried out in this research to explore the use of Brick dust as filler material for the bituminous mixture. The objective is intended to evaluate the performance of brick dust as fillers in Hot Asphalt Mix design, according to the test procedure specified by ASTM. Several specimens of hot asphalt mixture were prepared according to ASTM D 1559 using an aggregate blend with brick filler and aggregate blend without brick filler. The aggregate blending made by using Job mix formula to obtain the percentage of mixed material. For aggregate blended without brick G-1 32%, G-2 23%, and G-3 45% for Aggregate blended with brick filler G-1 30%, G-2 18%, G-3 45% and G-4 7%; where G-1 Coarse Aggregate 3/4, G-2 Coarse Aggregate 3/8, G-3 Fine Aggregate, and G-4 brick filler. It concluded that the results of the Marshall test of mix design showed satisfactory when hot asphalt mixed with these brick fillers. The Specimens blended with brick filler lead produce asphalt mixture with higher Marshall stability, lower flow, a less void filled with asphalt. Hence, brick dust can replace stone dust and cement filler in the bituminous paving mix. It is recommended to use brick dust as filler material in a bituminous paving mix may save considerable investment; as well as a reliable performance of the in-service highway can be achieved.
Abstract
A bituminous paving mixture is a mixture of coarse aggregate, fine aggregate, and bitumen mixed in suitable proportion to result in a strong and durable mix in order to withstand [...]
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International Journal of Scientific & Engineering Research
E. Quezon

International Journal of Scientific & Engineering Research (2016). Tarekegn Kumala, Prof. Emer T. Quezon, Bogale Shiferaw. Effect of Cycle Time and Signal Phase on Average Time Delay, Congestion and Level of Service: A Case Study at Hager Astedader Signalized Intersection in Addis Ababa. International Journal of Scientific & Engineering Research. 2016; 7(10): 524-530.

Abstract
High urbanization rate and Economic development have caused many challenges to transportation systems. Among these, long time delay and high fuel consumption of vehicles at congestion places are a few to mention. Some literatures have revealed that road traffic congestions are caused by inadequate infrastructures, long signal cycle time, and poor traffic management, such as incapable roads, inefficient public transit, and high travel demand. The research study was focused on the effect of traffic congestion on average time delay at a selected signalized road intersection in Addis Ababa. The study area was the Hager Astedadrerroad traffic signal intersection. The methodology that has been employed for the study was a quantitative descriptive research design method. The data needed were; road geometry data, signal data, traffic vehicles flow data including the pedestrian data were collected on-peak hours (with 15minutes intervals) from 7:30 to 9:30 AM and from 5:30 – 7:30 PM for the four consecutive working days. Data of traffic classes were extracted manually on a separate worksheet. The volume of each vehicle category was converted to the same vehicle category using the passenger car unit (PCU) of each vehicle class. Data analysis and processing have been performed using SIDRA (Signalized and Unsignalized Intersection Design and Research Aid) intersection software in order to know the traffic flow condition at the intersection. The result of average time delay was used to know the corresponding level of service and operational performance of the intersection. The outcomes of the research work minimize average time delay by adopting different improving strategies that range from low-cost measures such as improvements to signal timing and phase numbers, to high-cost measures such as intersection reconstruction, which be applied in the study area after knowing the amount of average time delay as well as the types of the level of service within the intersection area.
Abstract
High urbanization rate and Economic development have caused many challenges to transportation systems. Among these, long time delay and high fuel consumption of vehicles at [...]
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Regression Analysis of Index Properties of Soil as Strength Determinant for California Bearing Ratio (CBR)
D. Abdella, T. Abebe, P. Quezon, E. Quezon

GSJ (2017). Dino Abdella, Tadesse Abebe, Prof. Emer Tucay Quezon. Regression Analysis of Index Properties of Soil as Strength Determinant for California Bearing Ratio (CBR). GSJ. 2017; 5(6): 1-12

Abstract
Investigation of the variation in different soil types and origins is an essential task for Geotechnical engineers. To overcome the effects of this change, the Geotechnical engineers, as well as other professionals, attempted to develop empirical equations unique to a region and soil type to use the soil for its intended purpose. However, these empirical equations are more reliable for the kind of soil where there is a strong relationship of parameters is developed. Hence, it is good practice to develop empirical equations that best fit the soil available in the location that we can access. On the flexible pavement, the subgrade is considered to be an ideal layer to resist wheel load, and its CBR value is considered as the strength measuring a parameter. Conducting a CBR test is an expensive and time-consuming procedure. Also, it is challenging to mold the sample at a desired in-situ density in the laboratory. Furthermore, if the available soil is of poor quality, suitable additives are mixed with soil, and the resulting strength of the soil is assessed by the CBR value which is cumbersome. To overcome such a problem, statistical approaches such as regression-based models are used. This can be used for quick and easily determined parameters. Relative to this, the study has been conducted to develop an equation to show the relationship between the index properties and CBR values precisely located along WelkiteArekit –Hosanna Road of about 121km stretches. It was carried out using thirty samples retrieved from this road and tested in a laboratory. The test result of the regression-based statistical analysis was used to develop the predetermined relationship. The relationship development was performed in the form of an equation of CBR as a function of grain size parameters, Atterberg’s liquid limits, and compaction parameters by considering the effect of individual soil properties as well as the effect of a combination of soil properties on the CBR value. Based on the results of the study for both linear and multiple linear regression analyses, it was revealed that there was a relatively fair relationship obtained by combining plasticity index, the percentage of fine content, and maximum dry density which are strength determinants of fine-grained soils. Also, the results showed that the coefficient of determination for multiple linear regression is R2=0. 731, while for single linear regression is R2=0. 682. Therefore, it is concluded that the index properties of soils are sufficiently accurate in determining the CBR values, of which it can be utilized for preliminary characterization.
Abstract
Investigation of the variation in different soil types and origins is an essential task for Geotechnical engineers. To overcome the effects of this change, the Geotechnical [...]
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Effects of human behaviors and geometric factors in road traffic accidents a case study along Sululta-Fiche road, Ethiopia
E. Quezon

GJS (2017). Galeta Chala, Prof. Emer Tucay Quezon, Tarekegn Kumela. Effects of human behaviors and geometric factors in road traffic accidents: a case study along Sululta-Fiche road, Ethiopia. GSJ: 2017; 5(11). 163-172

Abstract
A road traffic accident was one of the severe problems which are affecting once’s a country and leading to death, injuries and property damage resulted in economic loss. The objective of this research was to investigate the effects of Human behaviors and Geometric factors in road traffic accidents along the road of Sululta-Fiche, which is located in the Northern Shewa of the Oromia region. Both probability sampling and non-probability sampling techniques were applied. The primary data were obtained from site observation of blackspot locations. While the secondary source of data was taken from records compiled by the North Shewa traffic office and Oromia Special Zone Surrounding Finfinne traffic Office. Descriptive and analytical design methods were used in this research, while the results were displayed by graphs, tables, and pie charts. From the study, the status of road traffic accidents showed that there were dramatically increase in accidents every year within the study period. A total of 830 crashes occurred in the past three years. From this, 237 accidents happened in 2012, 279 accidents in 2013, and 314 accidents in 2015. From the traffic police report analysis, there were 41 locations in Sululta Town, and 70 locations in Sululta Wereda, where those accidents happened. Based on the results of this research using the priority value approach, there were 12 selected locations in Sululta Town and 10 chosen locations in Sululta Wereda. Therefore, it is concluded that the significant factor in traffic accidents along Sululta –Fiche road was the driver errors such as over-speeding, night driving, and driving without attention, and it was followed by the geometric factors. These road deficiencies contributory to some errors of the drivers, which were inadequate road width, insufficient sight distance, and narrow bridge at sag curves, and improper intersection design. Based on the findings of the study, some of the countermeasures recommended reducing the road traffic accidents are the provision of speed limit signs to forewarn drivers, installation of speed barkers and rumble strips, widening the lane width of pavement, maintenance of the deteriorated road, repair of the road signs and provision of adequate sight visibility for drivers.
Abstract
A road traffic accident was one of the severe problems which are affecting once’s a country and leading to death, injuries and property damage resulted in economic loss. [...]
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Effectiveness of using Geosynthetic Material for Improvement of Road Construction and Performance Case Study on Adis Ababa
M. Gurara, K. Getachew, E. Quezon, E. Quezon

International Journal of Engineering Research & Technology (2017). Mikiyas. J Gurara, Kabtamu Getachew, Emer Quezon. Effectiveness of using Geosynthetic Material for Improvement of Road Construction and Performance - Case Study on Adis Ababa. International Journal of Engineering Research & Technology. 2017; (6)2: 640-642

Abstract
The research is concerned with the Effectiveness of geosynthetic to improve the performance of the pavement. It has been done on road construction projects under Addis Ababa Road Authority. Results indicated that the performance of bottom pavements structures constructed on poor subgrades with CBR values not greater than 4% was significantly enhanced using geosynthetic material. An increase of bearing capacity for subgrade and can improve the subgrade quality without excavating and filling of select material only by using geomembrane. Geosynthetic reinforcement in pavement design and construction should be widespread. Geosynthetic reinforcements are incorporated into permanent, paved roads either as base (or subbase) reinforcement - in flexible pavements to aid in the support of vehicular loads over the life of the pavement; or as subgrade restraint for construction of flexible or rigid roadways over weak subgrade conditions to aid in support of equipment loads on the unpaved base, or subbase, course during construction. Clearly, both base reinforcement and subgrade restraint with geosynthetics are proven techniques for use in pavement design and construction effectively.
Abstract
The research is concerned with the Effectiveness of geosynthetic to improve the performance of the pavement. It has been done on road construction projects under Addis Ababa [...]
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Cost and Benefit Analysis of Rigid and Flexible Pavement: A Case Study at Chancho –Derba-Becho Road Project
E. Quezon

International Journal of Scientific & Engineering Research (2016). Yonas Ketema, Prof. Emer T. Quezon, Getachew Kebede. Cost and Benefit Analysis of Rigid and Flexible Pavement: A Case Study at Chancho –Derba-Becho Road Project. International Journal of Scientific & Engineering Research. 2016; 7(10): 181-188

Abstract
Road construction projects have been implemented all over Ethiopia as part of the national development plan. Roads are one of the country’s basic infrastructural facilities where high amounts of the budget allocated every fiscal year planning period. Since the cost comprises of a large portion of government investment, a careful evaluation of the alternatives is of utmost importance to make the right choice for a particular project. In the history of Ethiopia's road development program, almost all of the road pavements are flexible, and it demands high foreign currency for asphalt material importing from abroad. In addition, flexible pavement needs to be maintained and rehabilitated within a few years after its initial construction. In view of the emerging cement factories and the availability of cement in Ethiopia, it is practical to consider rigid pavement as one of the alternatives. Relative to this, the research project was conducted with the main objective of identifying the cost and benefit of rigid and flexible pavements at the Chancho-Derba-Becho road project, North Showa Zone in Oromia. The research work had been focused on the specific objectives to determine and compare the life cycle costs of rigid and flexible pavements and to investigate all other qualitative merits of rigid and flexible pavement. To achieve these objectives, a review of related literature, design and specifications, observations and investigations of the actual pavement construction projects, evaluation of life cycle costs, the future value of money and present worth calculation were undertaken with an analysis period of 40 years. While the data considered was gathered through investigation at the actual rigid and flexible pavement projects, an examination of specifications, drawings and pavement design, Ethiopian Road Authority manuals, rehabilitation, and maintenance strategy. In this regard, the cost parameters investigated are initial construction cost, maintenance cost, rehabilitation cost, user’s cost, and salvage value, in addition to other qualitative and quantitative data. Based on the results of the research project, it revealed that the initial cost of rigid pavement was almost twice of the flexible pavement, but in the long run, the cost of flexible pavement per kilometer was found out to have 7.9 Million ETB more than the rigid pavement because of the incurring costs of maintenance through its design life. Therefore, it is suggested that Portland Cement Concrete Pavement (PCCP) shall be used in pavement construction to cater to local material requirements.
Abstract
Road construction projects have been implemented all over Ethiopia as part of the national development plan. Roads are one of the country’s basic infrastructural facilities [...]
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Comparative Study of Labor-Based Method and Machine-Based Method at Rural Road Construction and Maintenance in Jimma Zone, Oromia Region, Ethiopia
A. Dunffa, E. Quezon, E. Agon

American Journal of Civil Engineering (2017). Anwar Kassahun Dunffa, Emer Tucay Quezon, Elmer De Castro Agon. Comparative Study of Labor-Based Method and Machine-Based Method at Rural Road Construction and Maintenance in Jimma Zone, Oromia Region, Ethiopia. American Journal of Civil Engineering. Vol. 5, No. 4, 2017, pp. 212-219. doi: 10.11648/j.ajce.20170504.13

Abstract
The construction of physical infrastructure is contributory to poverty alleviation in every country. The road is one of the major components which is very significant in Ethiopia due to the lack of highly developed infrastructure, particularly in the rural road sector. Selection of the appropriate road construction and maintenance methods such as a labor-based method or machine-based method is necessary to be financially viable. Most rural road construction projects usually suffer from the problem of selecting the appropriate technology for the proposed project and implementation of the chosen technology. In Ethiopia, Universal Rural Road Access Program (URRAP) is an employment-intensive program for employment purposes as a first step, out of poverty using labor-based road construction. However, there are problems, constraints, and challenges encountered when implementing labor-based methods leading to enforce the mobilization of machines. The aim of this research study is to carry out the comparative analysis of ongoing and finished rural road projects in Jimma Zone and to establish qualitative and quantitative merit of various technologies used in rural road construction and maintenance. Results showed from financial cost comparison, the labor-based method was 47% cheaper than a machine-based method to carry out the same tasks. On the other hand, the share of unskilled average direct labor cost comprised an astounding 65% more of the total direct cost of a labor-based method. Also, the labor-based method directly employed 300 unskilled laborers per workday for a month to complete a 1.0 km section of a rural road.
Abstract
The construction of physical infrastructure is contributory to poverty alleviation in every country. The road is one of the major components which is very significant in Ethiopia [...]
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Combined Effects of Molasses-Lime Treatment on Poor Quality Natural Gravel Materials Used for Sub-Base and Base Course Construction
Y. Mamuye, E. Quezon, A. Geremew

GSJ (Select a year). Yibas Mamuye, Emer Tucay Quezon, Anteneh Geremew. Combined Effects of Molasses-Lime Treatment on Poor Quality Natural Gravel Materials Used for Sub-Base and Base Course Construction. GSJ: V2018; 6(7): 621-633

Abstract
At the time of industrial development, the production of large amounts of wastage required proper disposal. To reduce the disposal problem, utilization of wastage in construction works is a very important aspect. The reuse of industrial waste had gained high momentum for achieving sustainable waste management locally and globally. Keeping this in mind, research carried out to assess the utilization of molasses, lime, and molasses-lime for improving natural gravel for sub-base and base course construction from the Jimma Jiren quarry site. The natural gravel from this quarry site is known to have poor quality since it did not satisfy the ERA standard specification for sub-base and base course construction. To use Jiren natural gravel as a sub-base or base course construction material, it is necessary to improve its engineering properties. The laboratory test matrix in each test plan included variations in additive type, additive content, and curing period. It was established 8% cane molasses by weight of dry soil as the maximum for effective stabilization of natural gravel for sub-base construction, but not suitable for a base course layer. Results indicated that the natural gravel specimens from the Jiren quarry site stabilized with lime provided higher CBR values than molasses used alone. On the other hand, replacing 50% of lime content with molasses indicated better results than the performance of either individual additive. Therefore, the natural gravel blended with the molasses-lime combination is much better when it used for sub-base and base course construction to treat such an inferior quality of natural aggregates.
Abstract
At the time of industrial development, the production of large amounts of wastage required proper disposal. To reduce the disposal problem, utilization of wastage in construction [...]
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Geotechnical Conditions and Stability Analysis of Landslide Prone Area A Case Study in Bonga Town, South-Western Ethiopia
E. Quezon

International Journal of Scientific & Engineering Research (2017). Damtew Tsige, Prof. Emer T. Quezon, Dr. Kifle Woldearegay. Geotechnical Conditions and Stability Analysis of Landslide Prone Area: A Case Study in Bonga Town, South-Western Ethiopia. International Journal of Scientific & Engineering Research. 2017; 8(4): 239-248

Abstract
There were several slides and associated ground subsidence which brought significant impact on the cracking of walls and floor of several private and governmental buildings in Bonga Town. The principal and secondary roads were also affected by subsidence with vertical displacement up to 1m which hampered the traffic in the town. Water pipelines along the road were disturbed by the sliding which was later repaired. Cracking of the walls and floor of more than 120 private residences and more than 10 government buildings were recorded. The main highway that connects Bonga-TepiMasha via Alamo and Gatiba has been disrupted at four locations. This resulted in hampering traffic for several days. This research aimed to evaluate the cause and failure mechanism as well as the stability condition of the landslides. The study involved the investigation of the Geotechnical parameters of soil and the terrain characteristics to be used for the stability analysis of the slope, including distribution and characteristics of soils, the groundwater table, and the depth and geometry of the failures. The Slope stability analysis is supplemented by using Geo-studio 2004 software. Soil samples were collected and were tested for grain size analysis, distribution analysis (sieve & hydrometer) plastic limit, liquid limit, plasticity index, water content, unit weight of soil, specific gravity, and shear strength parameters following the ASTM procedures. Based on the findings, the landslides were triggered by heavy rainfall. Therefore, the main factors controlling the stability of the slope are soil type and characteristics, slope angle, water (surface and groundwater), and slope steepness. The design of the retaining wall is recommended to mitigate the impact of landslides in the study area.
Abstract
There were several slides and associated ground subsidence which brought significant impact on the cracking of walls and floor of several private and governmental buildings [...]
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Investigation of the Damping Ratio and Shear Modulus of Soil along Light Rail Transit Route in Megenagna-Hayat Road
E. Quezon

International Journal of Scientific & Engineering Research (2017). Abenezer Takele, Emer T. Quezon, Tadesse Abebe. Investigation of the Damping Ratio and Shear Modulus of Soil along Light Rail Transit Route in Megenagna-Hayat Road. International Journal of Scientific & Engineering Research. 2017; 8 (1):111-122

Abstract
Soil vibration may also cause by the movement of heavy vehicles and train, which affect adjacent structures along the route. The response of soils for incoming vibration from the train is measured by the dynamic properties of soils such as shear modulus and damping ratio. These soil parameters are very significant to study the ground motion as well as the site response of soil deposits under cyclic loading and soil-structure interaction. About this, the research study has been sought to give some information about the condition, specifically the shear modulus and damping ratio of the soil along the Addis Ababa light rail transit route from Megenagna to Hayat road. Also, this study was dealt with soil distribution along the route, which was conducted to determine soil properties. The sand replacement method was also utilized to investigate the controlling factors for the dynamic soil properties. From related literature, it was known that the dynamic soil properties are influenced by soil types and location of the soil profile. Five Test pits, designated A, B, C, D & E, were considered randomly for soil sampling to determine the properties of soil. The soil samples were taken from a depth of 2.5m below the surface of the roadside. Aside from the soil laboratory testing for common tests, another test was performed using a simple cyclic shear test for the representative samples. The values of normalized shear modulus and damping ratio are compared with already known curves from literature. The research study found out that the values of normalized shear modulus G/Gmax plotted against the shear strain, showed scattered points when it was compared with the curves of Seed and Idriss. Likewise, for the wet clay from the study area, all measured points were close to the known curve of the plot. On the other hand, the values of damping ratio were also compared to curves provided by Seed and Idriss. The Soil properties from all test pits had almost closer values as seen in the plot. However, the sample collected from test Pit D has the highest value of G/Gmax only, while samples from test Pit C has high values both for Gmax and Damping ratio. Test Pit C showed values of Dry density and liquid limit higher than the other test pits. Based on the comparison of the sand; for the strain less than 1%, all measured points of G/Gmax lying close to the extended curve given by Seed and Idriss. The strain of 0.2%, measured points of G/Gmax is closed to curve plot within the boundary, and it was below the curve given by Seed and Idriss. Likewise, for saturated clay, the measured points are close to the curve of Seed and Idriss. The values of damping ratio obtained for strain less than 1% obtained within the range of either the curves given by Seed and Idriss considers sand or clay soils. For strain, less than and equal to 1% the points lie within a range of clay. Therefore, the controlling factor that affects dynamic soil properties from a comparison of shear modulus and damping ratio curves based on consolidation pressure is the confining pressure, which shows high influence on the values of shear modulus and damping ratio based on the test results of the shear strain amplitudes. Index Terms—Damping Ratio, Dynamic Properties, Index property, Normalized Shear Modulus, Sand Replacement, Shear Modulus, Shear Strain Amplitude, Simple Cyclic Shear Test.
Abstract
Soil vibration may also cause by the movement of heavy vehicles and train, which affect adjacent structures along the route. The response of soils for incoming vibration from [...]
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Causes of Delays During Construction Phase of Road Projects due to the Failures of Contractor, Consultant, and Employer in Addis Ababa City Road Authority
E. Quezon

International Journal of Scientific & Engineering Research (2017). Amare, Y.; Quezon, ET.; Busier, M. Causes of Delays During Construction Phase of Road Projects due to the Failures of Contractor, Consultant, and Employer in Addis Ababa City Road Authority. International Journal of Scientific & Engineering Research. 2017; 8(3): 15-25.

Abstract
Construction delay considered as one of the most recurring problems in the implementation of construction projects. It is widely known to have an adverse impact on project success in terms of time, quality, and cost. The effect of construction delay is not only confined to the construction industry but also its influence on the overall economy of a country like Ethiopia. This research was conducted to assess the causes of excessive delays in the completion of road projects during the construction phase due to the failures of Employer, Consultant, and Contractor in Addis Ababa City Road Authority projects. Spearman rank correlation coefficient from the Relative Importance Index (RII) analysis was used to test the agreement between different groups of respondents who participated in the questionnaire survey and to rank the three construction parties according to their responsibility area and importance as perceived by the respondents which factor causing the delay of road projects. This research identified sixty-five (65) causes of delay. There were fifty-one (51) valid questionnaires received back from Contractors, Consultants, and Employer (AACRA). Based on the results, the contractors have the highest percentage of responsibility area that causes the delay of about 40%. While the second was on the part of the Employer, which comprised 26.15%, and the consultant which placed third of 23.08%. On the other hand, there were 10.77% of the respondents attested that the Shared groups (3-parties) have the responsibility area which causes project delay during the implementation phase. About this, the research study identified and ranked the top ten factors causing delays of construction projects in Addis Ababa City Road Authority. Poor ﬁnancial control of the project ranked 1st with Relative Importance Index (RII) of 0.905. Difficulties in financing projects by contractors ranked 2nd with the Relative Importance Index (RII) of 0.854. Type of project bidding and award (lowest bidder) ranked 3rd with an RII of 0.850. Poor site management and supervision of contractors ranked 4th with an RII of 0.839. Selecting inappropriate contractors ranked 5th with an RII of 0.823. Lack of high-technology mechanical equipment ranked 6th with an RII of 0.819. Inaccurate initial project scope estimate and Ineffective project scheduling ranked 7th and 8th with an RII of 0.803. Weak control of the project progress ranked 9th with an RII of 0.788. And the Contractor’s staff is not adequately trained in professional construction management techniques ranked 10th with an RII of 0.784. Therefore, it concluded that the main party Contractor did not perform properly his duties and obligations leading to the main contributory factor causing the failure of the project.
Abstract
Construction delay considered as one of the most recurring problems in the implementation of construction projects. It is widely known to have an adverse impact on project [...]
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A Study on the Effect of Time Duration by Vibrating or Tamping Fresh Concrete on the Compressive Strength of C-25 Concrete
A. Achalu, E. Quezon, G. Macarubbo

Effect of Time Duration by Vibrating or Tamping Fresh Concrete on the Compressive Strength (Select a year). Afework Achalu, Emer Tucay Quezon, Gerry Bangayan Macarubbo. A Study on the Effect of Time Duration by Vibrating or Tamping Fresh Concrete on the Compressive Strength of C-25 Concrete. American Journal of Construction and Building Materials. Vol. 2, No. 2, 2017, pp. 40-47. doi: 10.11648/j.ajcbm.20170202.11

Abstract
Many years ago, consolidation accomplished by laborers wielding a variety of spades, tampers, and similar tools. In Ethiopia, there is no enough knowledge by the laborers, while the site engineers ignored the correct application due to some constraints. The agreement of acceptable vibration level in fresh concrete to which tamping time duration is optimum is an issue to obtain the desired specific compressive strength. This research study aims to evaluate the maximum time length and techniques used to Vibrating or Tamping fresh concrete and its effect on the compressive strength of C-25 Concrete through internal Rodding. Therefore, to study the effects of the period by vibrating or tamping, the needle-type internal vibrator was used to test new concrete cubes based on ACI309R-96. The quality of concrete is important to make physical tests on materials used before any actual experiments to perform. The fresh concrete samples tested by using internal vibration methods and techniques of compaction with different time duration of 1sec, 2sec, 3sec, 4sec, and 5sec. These tests performed by using steel rod in fresh concrete to know the Optimum time of compaction by internal vibration on the cube test of new concrete. Laboratory experiments had been conducted to check the methods and techniques applied to construction sites, as well as site observation on the effects of the vibration time of fresh concrete on the compressive strength and flexural strength of C-25 Concrete with varying vibration time duration and steel rod tamping. Based on the results of cube tests of compressive strength of Concrete Samples have been checked on the 3rd day, 7th day, and 28th day. This research study found out that the Optimum period of compaction was 3sec to produce an acceptable right quality of the concrete mix. Likewise, the flexural strength of the Concrete Sample, when it tested in the laboratory on the 7th day and 28th day, results revealed that the flexural strength improved when vibration time increased, but the amount of water has to be reduced to obtain the desired strength. Finally, Tamping is needed to place fresh concrete in the mold correctly. Furthermore, new concrete produced should match the properties and avoid improper tamping or vibration applications. This situation must not cause differences in the compressive strength of concrete.
Abstract
Many years ago, consolidation accomplished by laborers wielding a variety of spades, tampers, and similar tools. In Ethiopia, there is no enough knowledge by the laborers, [...]
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Contract claim Analysis on Building Construction Project in Addis Ababa: A case study at Yeka Sub City
E. Quezon

International Journal of Scientific & Engineering Research (2016). Zenebe, E.; Quezon, ET.; Mosisa, A. Contract claim Analysis on Building Construction Project in Addis Ababa: A case study at Yeka Sub City. International Journal of Scientific & Engineering Research. 2016; 7(7): 1154-1160

Abstract
Contract claims are an inevitable fact of life in the construction industry. Contract claims are one of the problems that construction projects may face. Claims might cause many effects such as payment delay, an extension of time, and work suspension. The main aim of this research was an analysis of contract claims on building construction projects in Addis Ababa, Yeka Sub City by investigating the causes of contract claims and determining the factors to be considered in the selection of appropriate methodology for contract claims analysis. Literature and survey-based studies were made to provide an overview of the different contribution effects of contract claim analysis on building construction projects at the selected site. Interviews were also conducted with the three parties which have direct involvement in construction activities to get concrete ideas on the subject matter. A total of 75 questionnaires was distributed to respondents in Addis Ababa, Yeka Sub City building construction projects. Out of these 12 for client representatives, 35 for contractors representatives, 20 for consultant representatives, and 8 for other companies in order to identify claim causes that occurred in the study area. The quantitative data were analyzed using Excel and SPSS version 20 software, while qualitative data were analyzed by content analysis. The main factors of contact claim cause in the study area were identified. These factors further categorized into four groups; client-related, contract document-related, contractor related and consultant-related factors. While types of delays, knowing the strength and weakness of the project (project complexity) and conditions of the contract were identified as the factor to be considered in the selection of appropriate methodology for contract claim analysis. It is recommended that the three main contracting parties (Owner, Contractor, and Consultant) have responsibility for the effective accomplishment of the project. So each party would take part in their homework on time by developing technical knowledge about the effects of Contract claims on the progressive construction projects. Index Terms— causes, claim analysis, Contract claims, construction project, and risks.
Abstract
Contract claims are an inevitable fact of life in the construction industry. Contract claims are one of the problems that construction projects may face. Claims might cause [...]
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Evaluation of Health and Safety Practice in Building Construction: A Case Study in Addis Ababa
E. Quezon

International Journal of Scientific & Engineering Research (2016). Fekele, L.; Quezon, ET.; Macarubbo, YC. Evaluation of Health and Safety Practice in Building Construction: A Case Study in Addis Ababa. International Journal of Scientific & Engineering Research. 2016; 7(10): 122-131

Abstract
The construction industry has been seen as one of the hazardous industries. This is because the industry has a poor health and safety performance record compared to other industries all over the world. Labor law in every nation provides that it is the duty of an employer to ensure that every worker employed works under satisfactory, safe and healthy conditions. The research is focused on evaluating the health and safety issues in building construction projects in Addis Ababa, Ethiopia. The roles of the Client, Consultant and Contractor in health and safety consideration during project implementation were examined. It also determined the factors affecting health and safety performance of laborers. Whether, safety is used as criteria in selecting a contractor during the prequalification phase of public bidding was also identified. Building Construction Companies were involved in the sampling. All the information that could help in attaining the study objectives were collected, reviewed and formalized from the literature review. Data were collected and evaluated and the Relative Importance Index for each factor affecting health and safety was determined. The study determined the practical situation of building construction projects in consideration of health and safety, which was evaluated as low to medium. Relative Importance (RII) index of 12 factors affecting health and safety performance of labors were calculated. The top three factors identified were: (1) Non availability of a clear company Health and safety policy (0.85); (2) Inadequate enforcement of the existing building rules and regulations (0.82); and (3) Safety awareness of the company's top management (0.80). To improve the safety and health performance of building construction projects, the following major recommendations were proposed: each building, construction projects should have their own safety and health policy; include safety as a pay item in contract document; and allocate budget and time frames for health and safety in the contract document. Index Terms— Addis Ababa, Company Policies, Hazards, Health and Safety Practices, Rules and Regulations .
Abstract
The construction industry has been seen as one of the hazardous industries. This is because the industry has a poor health and safety performance record compared to other [...]
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Assessment on the effects of weather change on road construction planning at some selected projects in Addis Ababa and Oromia
E. Quezon

International Journal of Scientific & Engineering Research (2016). Befkadu, A.; Quezon, ET.; Busier, M. Assessment on the effects of weather change on road construction planning at some selected projects in Addis Ababa and Oromia. International Journal of Scientific & Engineering Research. 2016; 7(12): 134-145.

Abstract
Road construction in Ethiopia is in high demand to meet its short and long-term goals in infrastructure development programs. The road network is constructed radiating outwards North-South and East-West direction of the Capital City. Some projects are experiencing weather malady due to changing weather conditions in project locations. The study area of this research was focused on some selected projects in Addis Ababa and Oromia. The research had been addressed the effects of changes in weather in the three project planning phases, namely conception planning, design planning, and construction planning. A quantitative research design was used in this study. A literature review was undertaken and the result of which showed that the effects of weather changes are not extensively researched in the construction industry and there are limited references on the effects of weather change within the road construction industry. Sample data were obtained from sixty-three (63) construction practitioners through questionnaires, which were mailed to prospective respondents to assess their opinions. Questions were subdivided into three relevant areas covering demographics, experience with weather change factors, and the effects of weather change on road construction project planning. The study found that the effects of weather change on road construction project planning are similar to those found in other construction industries. The effects of weather change factors on road project planning vary with planning phases. These weather change factors as well as their effects were listed and ranked based on their frequency of occurrence and mean score. An independent sample t-test was used to compare respondents’ opinions on weather change effects between the two sample groups taken in Addis Ababa and part of Oromia. A partial correlation was also employed to identify the relationship between weather change factors and their effect on road construction project planning using SPSS-20. Delay of site preparation activities as a result of weather change on road project conception planning phase has a mean score of 4.30 Addis Ababa and 4.00 in for Oromia, while the influence of weather change on the selection and specification of construction materials for road project design planning phase has the highest mean score of 4.23 for Addis Ababa and 4.03 for Oromia. The effect of weather change on road workers' physiological comfort and quality of work for the road project construction planning phase has the highest mean score of 4.80 and 4.58 in Addis Ababa and Oromia, respectively. The study concludes with recommendations for potential research and with useful information and considerations on the effects of weather change on road construction project planning for construction professionals and project managers.
Abstract
Road construction in Ethiopia is in high demand to meet its short and long-term goals in infrastructure development programs. The road network is constructed radiating outwards [...]
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Performance of stochastic restricted and unrestricted two-parameter estimators in linear mixed models
N. Ganjealivand, F. Ghapani, A. Zaherzadeh, F. Hormozinejad

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (2), 29

Abstract
In this article, two parameter estimation using penalized likelihood method in the linear mixed model is proposed. In addition, by considering the stochastic linear restriction for the vector of fixed effects parameters we are introduced the stochastic restricted two parameter estimation. Methods are proposed for estimating variance parameters when unknown. Also, the superiority conditions of the two parameter estimator over the best linear unbiased estimator, and the stochastic restricted two parameter estimator over the stochastic restricted best linear unbiased estimator are obtained under the mean square error matrix sense. Methods are proposed for estimating of the biasing parameters. Finally, a simulation study and a numerical example are given to evaluate the proposed estimators.
Abstract
In this article, two parameter estimation using penalized likelihood method in the linear mixed model is proposed. In addition, by considering the stochastic linear restriction [...]
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Data-sets of the model basin experiments carried out within the NICESHIP project
J. Gutiérrez Romero, S. Ruiz-Capel, J. Esteve-Perez, B. Zamora-Parra, J. Luna-Abad

NICESHIP PROJECT (2021). 1

Abstract
Photogrammetry data-sets corresponding to the model basin experiments carried out within the NICESHIP project.
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Immunisation for HIV-Infected People
D. Cebo

(2017). Current Topics in Virology

Abstract
Vaccines are critical components for protecting HIV-infected adults from an increasing number of preventable diseases. However, missed opportunities for vaccination among HIV-infected persons persist, likely due to concerns regarding the safety and efficacy of vaccines, as well as the changing nature of vaccine guidelines. In addition, the optimal timing of vaccination among HIV-infected adults with regard to HIV stage and receipt of antiretroviral therapy remain an important question. This article provides a review of the current recommendations regarding vaccines among HIV-infected adults and a comprehensive summary of the evidence-based literature of the benefits and risks of vaccines among this vulnerable population.
Abstract
Vaccines are critical components for protecting HIV-infected adults from an increasing number of preventable diseases. However, missed opportunities for vaccination among [...]
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Discordant CD4 cell count and viral load responses to antiretroviral therapy
D. Cebo

(2017). Current Trends in Immunology

Abstract
Most patients starting highly active antiretroviral therapy (HAART) show suppression of HIV replication below the level of detection (currently <50 HIV-1 RNA copies/mL in most assays), and experience a gradual rise in CD4 lymphocyte count, which may continue for several years. The CD4 count response is generally related to the degree of viral load suppression, and this typical pattern of CD4 and viral load response is associated with a marked improvement in prognosis. In some patients, however, there is discordance in the response. Either there is suppression of viral load but poor recovery of immune function, characterized by little or no CD4 cell count increase or, conversely, an improvement in CD4 cell count with incomplete or delayed viral load suppression. Little is known about the pathogenesis of discordant responses, which seems to depend on the interaction of a multitude of viral, host and treatment-related factors. Available evidence indicates that discordant responses are associated with an intermediate risk of death or clinical progression. At present, recommendations for the clinical management of patients with discordant responses to antiretroviral therapy are largely based on observational, uncontrolled data. The development of standardized and universally accepted definitions of discordant responses is necessary to allow meaningful comparisons between studies to be made, as well as to help in the design of trials of possible therapeutic interventions.
Abstract
Most patients starting highly active antiretroviral therapy (HAART) show suppression of HIV replication below the level of detection (currently <50 HIV-1 RNA copies/mL [...]
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PARAMETRIC MODELLING ON THE RELATIONSHIPS BETWEEN ATTERBERG LIMITS AND COMPACTION CHARACTERISTICS OF FINE-GRAINED SOILS
P. Quezon, E. Quezon

International Journal of Advanced Research in Engineering and Applied Sciences (2019). Worku Firomsa, Prof. Emer Tucay Quezon; (2019). “PARAMETRIC MODELLING ON THE RELATIONSHIPS BETWEEN ATTERBERG LIMITS AND COMPACTION CHARACTERISTICS OF FINE-GRAINED SOILS.” International Journal of Advanced Research in Engineering and Applied Sciences, 8(7), 1-20. https:// www.garph.co.uk

Abstract
Compaction is one of the essential engineering techniques, performed to assure the stability of soils based on specified strength. However, in most construction projects such as large-scale projects, obtaining the desired compaction characteristics, namely optimum moisture content (OMC) and maximum dry density (MDD), becomes time-consuming. In this case, predicting the compaction characteristics from the Atterberg's limits that involve a more straightforward and quicker method of testing becomes a vital task. This study focused on obtaining valid correlations between Atterberg's limit parameters and compaction characteristics of fine-grained soils. A series of laboratory tests for 50 samples conducted for the investigation. Statistical relationships of all the parameters were analyzed. The laboratory test results indicated that both OMC and MDD showed a strong correlation with LL and PL together using multiple linear regressions than with single parameters from single linear regression. Therefore, the study concluded that during the prediction of OMC and MDD from Atterberg's limits, the combined parameters of Atterberg's limits should be used rather than single parameters. It is recommended, the result of this research could be applied in different civil engineering practices, directly related to the parameters to be known.
Abstract
Compaction is one of the essential engineering techniques, performed to assure the stability of soils based on specified strength. However, in most construction projects such [...]
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Evaluation on the Performance of Lowest Responsive Bid Contract and the Quality of Materials Used on Governmental Building Projects in Jimma Town
E. Quezon

International Journal of Scientific & Engineering Research (2016). BinyamLetarge, Emer T. Quezon, Yolente C. Macarubbo. Evaluation on the Performance of Lowest Responsive Bid Contract and the Quality of Materials Used on Governmental Building Projects in Jimma Town. International Journal of Scientific & Engineering Research. 2016; 7(12): 60-73

Abstract
Construction industry participants have started recognizing that accepting the least bid price does not guarantee maximum value. Continuous problems of inferior quality of constructing facilities, high incidence of claims and litigation, frequent cost overruns, and use of poor quality of materials have become the main features of Ethiopian’s public construction work contracts. This research was undertaken to evaluate the performance of publicly owned construction projects awarded on a lowest bid awarding system, to determine the effect of advance payment on the contractor’s performance, compare lowest and average bid systems, and check the quality of local construction materials use by lowest price won contracts. A literature review was carried out to identify different practices and floated questionnaire survey and laboratory test was conducted for selected and expected materials. Two alternative bid evaluation methods were discussed and suggested the better one from a performance point of view. The questionnaire was distributed to contractors, clients, consultants, and other related professionals. Additionally, interviews were conducted with them. A total of 88 questionnaires were distributed, including laboratory test results for selected and expected materials found in Jimma town. The data were collected and 80 valid questionnaires were analyzed by using SPSS-20, Excel, and laboratory test results requirement. The study identified that the causes of the poor performance of contractors were won projects with the lowest price; therefore more of the respondents do not like the lowest bidding method. Advance payment is the main solution to support the financial problems of contractors, but instead of paying in cash, purchasing the necessary construction materials is seen as an alternative to protect contractors from using the money for other uses. Obviously known that in the current bid awarding method of Ethiopia, most of the time, in order to be the winner of the bid price should be lesser. This leads the bidder not to get adequate profit, this pushes them to use poor quality of local construction materials. Finally, this work provides valuable information to the Ethiopian government, clients, consultants and contractors, and other stakeholders who desire to improve bidding methods; usage of advance payment; ways to improve performance of contractors, and to protect the project from contractors using poor quality of construction materials.
Abstract
Construction industry participants have started recognizing that accepting the least bid price does not guarantee maximum value. Continuous problems of inferior quality of [...]
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Nonlinear Dynamics of Structures: Projects, Tests, Damping, Damages and Their Diagnostics
V. Kulyabko

WCCM-ECCOMAS2020.

Abstract
The paper considers the features of nonlinear modeling of problems of dynamics of structures at different stages: design, testing and operation. Recommendations are given for nonlinear dynamic calculations and dynamic diagnostics (certification, identification of structural defects, etc.).
Abstract
The paper considers the features of nonlinear modeling of problems of dynamics of structures at different stages: design, testing and operation. Recommendations are given [...]
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Multiphysics Modelling of a Hybrid Rocket Engine
A. Ferrero, F. Masseni, L. Muscarà, D. Pastrone

WCCM-ECCOMAS2020.
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Multidisciplinary Modelling, Analysis and Optimisation for Aircraft and System Level Design and Validation
W. J. Vankan, W. Lammen, E. Baalbergen

WCCM-ECCOMAS2020.

Abstract
Against the background of the big environmental and societal challenges as formulated for example in Flightpath 2050, current developments in aircraft design are aiming at further emission reduction through integrated, unconventional propulsion, systems and airframe innovations. This requires the further integration of methods for multidisciplinary modelling, analysis and optimization for aircraft design, but also for propulsion and system level designs. Moreover, experimental validation of the methods and physical testing of critical unconventional propulsion and system designs are prerequisites for industrially relevant development processes. This paper presents some key technologies for computationally efficient collaborative MDO (multidisciplinary design and optimization) frameworks for multidisciplinary design and validation of advanced aeronautic products like aircraft and propulsion systems.
Abstract
Against the background of the big environmental and societal challenges as formulated for example in Flightpath 2050, current developments in aircraft design are aiming at [...]
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A Bi-Fidelity DG-IMEX Method for the Linear Transport Equation with Random Parameters
L. Liu

WCCM-ECCOMAS2020.

Abstract
In this paper, we introduce a bi-fidelity stochastic collocation (SC) method for the linear transport equation with diffusive scaling and high-dimensional random inputs characterized by random variables. For the high-fidelity linear transport model, the asymptotic-preserving Discontinuous Galerkin implicit-explicit method in the micro-macro decomposition framework is used. We discuss different choices of low-fidelity models and conduct the corresponding uniform error estimates for the bi-fidelity method. Extensive numerical tests are presented to validate our bi-fidelity SC method.
Abstract
In this paper, we introduce a bi-fidelity stochastic collocation (SC) method for the linear transport equation with diffusive scaling and high-dimensional random inputs characterized [...]
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Numerical Analysis of a Mechanical De-Icing Process by Low Frequency Oscillation of a CFRP Layer
F. Grubert, M. Nuño, K. Schröder

WCCM-ECCOMAS2020.

Abstract
De-icing of general aviation aircraft is usually realized by chemical or thermal processes. These lead to an increase in fuel consumption or usage of electrical energy. Mechanical de-icing is a way to significantly reduce this consumption. In mechanical de-icing, a surface is deformed so that the required failure mechanisms are induced in the ice, causing it to detach. In this paper, the release behavior of ice on a CFRP layer is investigated. The CFRP layer consists of two plies, each 0.3 mm thick. A numerical calculation is performed to determine the natural frequency and the required amplitudes of the vibration. In addition, the relationship between the various failure mechanisms of ice and the ice layer thickness, as well as the control values are determined. Tests are also being conducted to demonstrate the feasibility of mechanical de-icing. For this purpose, the surface of a CFRP layer is iced with water in a climate chamber at -20°C. A modal shaker is connected to the CFRP and generates the required displacements at desired frequencies to observe the detachment of the ice.
Abstract
De-icing of general aviation aircraft is usually realized by chemical or thermal processes. These lead to an increase in fuel consumption or usage of electrical energy. Mechanical [...]
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