Documents published in 2021 : Scipedia

D6.3 Report on stochastic optimisation for simple problems
Q. Ayoul-Guilmard, S. Ganesh, F. Nobile, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 11

Abstract
This report addresses the general matter of optimisation under uncertainties, following a previous report on stochastic sensitivities (deliverable 6.2). It describes several theoretical methods, as well their application into implementable algorithms. The specific case of the conditional value at risk chosen as risk measure, with its challenges, is prominently discussed. In particular, the issue of smoothness – or lack thereof – is addressed through several possible approaches. The whole report is written in the context of high-performance computing, with concern for parallelisation and cost-efficiency.
Abstract
This report addresses the general matter of optimisation under uncertainties, following a previous report on stochastic sensitivities (deliverable 6.2). It describes several [...]
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“Optimization of reinforcing steel with Genetic Algorithms for the design of concrete columns”
L. Verduzco Martínez

Optimización de acero de refuerzo con algoritmos genéticos para el diseño de columnas de concreto (2020). In process of publication

Abstract
Is presented hereby the creation of an optimization program for the design of reinforcing steel for any type of structural elements which may be considered as columns, pillar, pilots or dies, subjected to flexo-compression mechanic stresses for rectangular cross sections elements with the support of numeric methods and meta-heuristic algorithms for the optimization of constructions costs, particularly ''the Genetic algorithm'', adapting such algorithms to the optimization problem so that it makes the resultant designs practical and convenient for its application in the construction industry, based on certain criteria from [[#cite-6|[6]]] and questioning other. It will be shown how such optimization algorithm was adapted to the problem, as well as other general numeric methods for engineering and others developed specifically for structural engineering for the optimal design of this sort of concrete elements. Moreover, sensibility cost analysis of unitary construction prices are presented as well, with which the objective function for the optimization algorithm was created. At the end, results of various experiments with and without the optimization program are shown, making comparisons between different structural models regarding cost and geometry.
Abstract
Is presented hereby the creation of an optimization program for the design of reinforcing steel for any type of structural elements which may be considered as columns, pillar, [...]
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D5.3 Report on theoretical work to allow the use of MLMC with adaptive mesh refinement
Q. Ayoul-Guilmard, S. Ganesh, M. Nuñez, R. Tosi, F. Nobile, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 10

Abstract
This documents describes several studies undertaken to assess the applicability of MultiLevel Monte Carlo (MLMC) methods to problems of interest; namely in turbulent fluid flow over civil engineering structures. Several numerical experiments are presented wherein the convergence of quantities of interest with mesh parameters are studied at different Reynolds’ numbers and geometries. It was found that MLMC methods could be used successfully for low Reynolds’ number flows when combined with appropriate Adaptive Mesh Refinement (AMR) strategies. However, the hypotheses for optimal MLMC performance were found to not be satisfied at higher turbulent Reynolds’ numbers despite the use of AMR strategies. Recommendations are made for future research directions based on these studies. A tentative outline for an MLMC algorithm with adapted meshes is made, as well as recommendations for alternatives to MLMC methods for cases where the underlying assumptions for optimal MLMC performance are not satisfied.
Abstract
This documents describes several studies undertaken to assess the applicability of MultiLevel Monte Carlo (MLMC) methods to problems of interest; namely in turbulent fluid [...]
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D6.4 Report on stochastic optimisation for unsteady problems
Q. Ayoul-Guilmard, F. Nobile, S. Ganesh, M. Nuñez, A. Kodakkal, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 9

Abstract
This report brings together methodological research on stochastic optimisation and work on benchmark and target applications of the ExaQute project, with a focus on unsteady problems. A practical, general method for the optimisation of the conditional value at risk is proposed. Three different optimisation problems are described: an oscillator problem selected as a suitable trial and illustration case; the shape optimisation of an airfoil, chosen as a benchmark application in the project; the shape optimisation of a tall building, which is the challenging target application set for ExaQUte. For each problem, the current developments and results are presented, the application of the proposed method is discussed, and the work to be done until the end of the project is laid out.
Abstract
This report brings together methodological research on stochastic optimisation and work on benchmark and target applications of the ExaQute project, with a focus on unsteady [...]
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D3.2 Report on parallel in time methods and release of the solvers
M. Caicedo, J. Principe, R. Codina, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 8

Abstract
In this deliverable we provide the details related to the design, implementation, and scalability analysis of Space Time Balancing Domain Decomposition by Constraints (STBDDC) preconditioners that have been implemented in the FEMPAR project [8]. First, we describe the state of the art of space-time methods in Sect. 2 and we then provide some details of our particular implementation in Sect. 3. Next, in Sect. 4, we present a detailed description of the numerical experiments performed during the project showing the excellent scalability results that these algorithms permit to achieve. At the same time, we show the limitations of these algorithms when dealing with nonlinear problems. Finally we draw some concluding remarks in Sect. 5.
Abstract
In this deliverable we provide the details related to the design, implementation, and scalability analysis of Space Time Balancing Domain Decomposition by Constraints (STBDDC) [...]
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D5.4 Report on MLMC for time dependent problems
Q. Ayoul-Guilmard, S. Ganesh, M. Nuñez, R. Tosi, F. Nobile, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 7

Abstract
In this report, we study the use of Multi-Level Monte Carlo (MLMC) methods for time dependent problems. It was found that the usability of MLMC methods depends strongly on whether or not the underlying time dependent problem is chaotic in nature. Numerical experiments are conducted on both simple problems, as well as fluid flow problems of practical interest to the ExaQUte project, to demonstrate this. For the non-chaotic cases, the hypotheses that enable the use of MLMC methods were found to be satisfied. For the chaotic cases, especially the case of high Reynolds’ number fluid flow, the hypotheses were not satisfied. However, it was found that correlations between the different levels were high enough to merit the use of multi-fidelity or control-variate approaches. It was also noted that MLMC methods could work for chaotic problems if the time window of analysis were chosen to be small enough. Future studies are proposed to examine this possibility.
Abstract
In this report, we study the use of Multi-Level Monte Carlo (MLMC) methods for time dependent problems. It was found that the usability of MLMC methods depends strongly on [...]
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D7.2 Finalization of "deterministic" verification and validation tests
A. Apostolatos, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 6

Abstract
This deliverable focus on the verification and validation of the solvers of Kratos Multiphysics which are used within ExaQUte. These solvers comprise standard body-fitted approaches and novel embedded approaches for the Computational Fluid Dynamics (CFD) simulations carried out within ExaQUte. Firstly, the standard body-fitted CFD solver is validated on a benchmark problem of high rise building - CAARC benchmark and subsequently the novel embedded CFD solver is verified against the solution of the body-fitted solver. Especially for the novel embedded approach, a workflow is presented on which the exact parameterized Computer-Aided Design (CAD) model is used in an efficient manner for the underlying CFD simulations. It includes: A note on the space-time methods Verification results for the body-fitted solver based on the CAARC benchmark Workflow consisting of importing an exact CAD model, tessellating it and performing embedded CFD on it Verification results for the embedded solver based on a high-rise building API definition and usage
Abstract
This deliverable focus on the verification and validation of the solvers of Kratos Multiphysics which are used within ExaQUte. These solvers comprise standard body-fitted [...]
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D1.3 First public Release of the solver
Q. Ayoul-Guilmard, R. Badia, J. Ejarque, S. Ganesh, F. Nobile, M. Nuñez, C. Soriano, C. Roig, R. Rossi, R. Tosi

Open Access Repository of the ExaQUte project: Deliverables (2021). 5

Abstract
This deliverable presents the software release of Kratos Multiphysics, together with the XMC library, Hyperloom and PyCOMPSs API definition [8]. This report is meant to serve as a supplement to the public release of the software. Kratos is “a framework for building parallel, multi-disciplinary simulation software, aiming at modularity, extensibility, and high performance. Kratos is written in C++, and counts with an extensive Python interface”. XMC is a python library for hierarchical Monte Carlo algorithms. Hyperloom and PyCOMPSs are environments for enabling parallel and distributed computation.
Abstract
This deliverable presents the software release of Kratos Multiphysics, together with the XMC library, Hyperloom and PyCOMPSs API definition [8]. This report is meant to serve [...]
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D1.1 Solvers "stub" implementation of the capabilities to be delivered
R. Rossi, I. López, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 4

Abstract
The current deliverable describes the initial API available for the solvers. The API is intended to be based on the Kratos Multiphysics fraemework and will evolve during the project. The current deliverable describes the essential features of the interface and provides an initial working implementation to be used as a basis for the future developements. The initial implementation described here is currently operative on the master branch of Kratos. As of the end of July 2018 (moment of handing in of current deliverable) the interface is operative and is being used “in production”. Nevertheless, it still does not fully support the model serialization capabilities that are needed for pyCompSS and HyperLoom. The interface is documented in the project wiki page [wiki]. The same documentation is also presented in the current deliverable.
Abstract
The current deliverable describes the initial API available for the solvers. The API is intended to be based on the Kratos Multiphysics fraemework and will evolve during the [...]
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D1.4 Final public Release of the solver
Q. Ayoul-Guilmard, S. Ganesh, F. Nobile, R. Badia, J. Ejarque, L. Cirrottola, A. Froehly, B. Keith, A. Kodakkal, M. Nuñez, C. Roig, R. Tosi, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 3

Abstract
This deliverable presents the final software release of Kratos Multiphysics, together with the XMC library, Hyperloom and PyCOMPSs API definitions [13]. This release also contains the latest developements on MPI parallel remeshing in ParMmg. This report is meant to serve as a supplement to the public release of the software. Kratos is “a framework for building parallel, multi-disciplinary simulation software, aiming at modularity, extensibility, and high performance. Kratos is written in C++, and counts with an extensive Python interface”. XMC is “a Python library for parallel, adaptive, hierarchical Monte Carlo algorithms, aiming at reliability, modularity, extensibility and high performance“. Hyperloom and PyCOMPSs are environments for enabling parallel and distributed computation. ParMmg is an open source software which offers the parallel mesh adaptation of three dimensional volume meshes.
Abstract
This deliverable presents the final software release of Kratos Multiphysics, together with the XMC library, Hyperloom and PyCOMPSs API definitions [13]. This release also [...]
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D2.2 First release of the octree mesh-generation capabilities and of the parallel mesh adaptation kernel
A. Martín, L. Cirrottola, A. Froehly, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 2

Abstract
This document presents a description of the octree mesh-generation capabilities and of the parallel mesh adaptation kernel. As it is discussed in Section 1.3.2 of part B of the project proposal there are two parallel research lines aimed at developing scalable adaptive mesh refinement (AMR) algorithms and implementations. The first one is based on using octree-based mesh generation and adaptation for the whole simulation in combination with unfitted finite element methods (FEMs) and the use of algebraic constraints to deal with non-conformity of spaces. On the other hand the second strategy is based on the use of an initial octree mesh that, after make it conforming through the addition of templatebased tetrahedral refinements, is adapted anisotropically during the calculation. Regarding the first strategy the following items are included: Description of the octree-based AMR kernel with space-filling curves. Description of a outer, wrapping AMR layer supporting FEM needs. Numerical results in a distributed environment. Regarding the second strategy the following items are included: An outline of the anisotropic mesh adaptation algorithm. A description of the state of the art of the implementation. A discussion on the ongoing and future work.
Abstract
This document presents a description of the octree mesh-generation capabilities and of the parallel mesh adaptation kernel. As it is discussed in Section 1.3.2 of part B of [...]
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D1.2 First realease of the softwares
R. Tosi, R. Amela, M. Nuñez, C. Roig, R. Badia, R. Rossi, C. Soriano

Open Access Repository of the ExaQUte project: Deliverables (2021). 1

Abstract
This deliverable presents the software release of the Kratos Multiphysics software [3], ”a framework for building parallel, multi-disciplinary simulation software, aiming at modularity, extensibility, and high performance. Kratos is written in C++, and counts with an extensive Python interface”. In this deliverable we focus on the development of Uncertainty Quantification inside Kratos. This takes place in the MultilevelMonteCarloApplication, a recent development inside the software that allows to deal with uncertainty quantification.
Abstract
This deliverable presents the software release of the Kratos Multiphysics software [3], ”a framework for building parallel, multi-disciplinary simulation software, aiming [...]
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Trabajo de Investigación: Sector del Acero
. center|162px, V. Harasta

Valentina Makena Harasta's personal collection (2021). 1

Abstract
Este trabajo de investigación tendrá el propósito de formalizar una mirada histórica del sector siderúrgico en la Argentina (centralizándose en el sector del acero) a partir de la década de los 40 hasta la actualidad, resaltando su impacto en el sector económico al ser considerado como un grupo estratégico para el desarrollo económico en nuestro país. Se intentará desarrollar cinco cuestiones esenciales: el nivel de actividad dentro del sector según la época, el nivel de concentración empresarial, su impacto en el mercado laboral, el comercio exterior en el mismo y, por último, una reflexión en base a lo investigado.
Abstract
Este trabajo de investigación tendrá el propósito de formalizar una mirada histórica del sector siderúrgico en la Argentina (centralizándose [...]
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CHILDREN’S RIGHTS TO EDUCATION IN SOUTH AFRICA TWENTY YEARS AFTER DEMOCRACY: A REFLECTION ON ACHIEVEMENTS, PROBLEMS AND AREAS FOR FUTURE ACTION
B. Chitsamatanga, B. CHITSAMATANGA

(2020). B BANDA

Abstract
Education is the most powerful weapon that can be used to change the world. These noble words by Nelson Mandela provide a yardstick against which South Africa can measure whether the rights of the child, key of which is the right to education, are progressively being realised. Towards this end, education is seen as the ultimate foundation and solution for the attainment of freedom, democracy and human rights; social justice and equality for South African children. Thus, the question remains: after more than twenty years of democracy, to what extent can South Africa pride herself of having achieved this noble goal? This article reflects on the national effort to realise the rights of children to education against the frameworks provided for in international and regional instruments. The latter require governments’ commitment to ensure that the rights of children to education in particular, are implemented and respected. An analysis will be made on how the new democratic government has succeeded to reverse the discriminatory policies, law and practice of the apartheid era. It further discusses how the existing education system translates the attainment of children rights to education in terms of the standard and quality of teaching and learning; existing school facilities; racial segregation; human and financial resources; and safe school learning environment. The article concludes by identifying measures that need to be taken by all stakeholders in order to promote the realisation of children’s right to education.
Abstract
Education is the most powerful weapon that can be used to change the world. These noble words by Nelson Mandela provide a yardstick against which South Africa can measure [...]
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Long-Term Orbit Dynamics of Decommissioned Geostationary Satellites
S. Proietti, R. Flores, M. Pontani

Acta Astronautica (2020). AA 8423

Abstract
In nominal mission scenarios, geostationary satellites perform end-of-life orbit maneuvers to reach suitable disposal orbits, where they do not interfere with operational satellites. This research investigates the long-term orbit evolution of decommissioned geostationary satellite under the assumption that the disposal maneuver does not occur and the orbit evolves with no control. The dynamical model accounts for all the relevant harmonics of the terrestrial gravity field at the typical altitude of geostationary orbits, as well as solar radiation pressure and third-body perturbations caused by the Moon and the Sun. Orbit propagations are performed using two algorithms based on different equations of motion and numerical integration methods: (i) Gauss planetary equations for modified equinoctial elements with a Runge-Kutta numerical integration scheme based on 8-7th-order Dorman and Prince formulas; (ii) Cartesian state equations of motion in an Earth-fixed frame with a Runge-Kutta Fehlberg 7/8 integration scheme. The numerical results exhibit excellent agreement over integration times of decades. Some well-known phenomena emerge, such as the longitudinal drift due to the resonance between the orbital motion and Earth’s rotation, attributable to the J2 term of the geopotential. In addition, the third-body perturbation due to Sun and Moon causes two major effects: (a) a precession of the orbital plane, and (b) complex longitudinal dynamics. This study proposes an analytical approach for the prediction of the precessional motion and show its agreement with the (more accurate) orbit evolution obtained numerically. Moreover, long-term orbit propagations show that the above mentioned complex longitudinal dynamics persists over time scales of several decades. Frequent and unpredictable migrations toward different longitude regions occur, in contrast with the known effects due only to the perturbative action of J2
Abstract
In nominal mission scenarios, geostationary satellites perform end-of-life orbit maneuvers to reach suitable disposal orbits, where they do not interfere with operational [...]
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Effects of surging and heaving movements of platform on mechanical behaviors of SCT installation pipe
F. Wang, N. Chen, Q. Yang, X. Ji

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 12

Abstract
The effects of surging and heaving movements of installation platform on mechanical behaviors of SCT installation pipe was studied. Movements of SCT installation platform, ocean wave and current, water depth, SCT weight, installation pipe specification and those dominate the mechanical behaviors of installation pipe and SCT installation precision were considered. The results indicate that surging movement of the platform is the main factor that dominate the deformation of the installation pipe. The surging and heaving movements have significant effect on the tension force loaded on the installation pipe and thus need to be considered when designing SCT installation.
Abstract
The effects of surging and heaving movements of installation platform on mechanical behaviors of SCT installation pipe was studied. Movements of SCT installation platform, [...]
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Design and fabrication of a drill guide template for total elbow arthroplasty
M. Heidari, P. Rahmanivahid, F. Yusof, J. Kashani

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 5

Abstract
Optimum implant positioning and technique used for its alignment are vital parameters to improve clinical results. Visual cues and jigs are utilized in the recent surgical techniques, which lead to some errors in the flexion-extension axis identification. Surgeons have used computer-assisted surgery for the alignment of the hip, knee, and shoulder. However, there is a restricted application of this technology to the elbow. In this study, a technique was used to model a drill guide template to precisely place an implant in the bone. The computed tomography dataset was used to construct four different elbow bones, and an elbow implant was modeled. The surgical drill guides were designed based on the computed tomography data. The drill guide templates and constructed bones were fabricated, using a 3D printer. The accuracy of the surgical guides was validated experimentally. The results showed that the mean deviations between the achieved and planned positions of the hole at the bone apex and base of bones were less than those reported in previous studies in both medial/lateral and posterior/anterior positions. The low positioning errors observed in this study proposed that the implant’s location can be precisely aligned to its target using the introduced technique.
Abstract
Optimum implant positioning and technique used for its alignment are vital parameters to improve clinical results. Visual cues and jigs are utilized in the recent surgical [...]
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Spare parts supply network optimization with uncertain distributed lead times and demands
Y. Wang, Q. Shi, L. Li, F. Li, W. Xia

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 1

Abstract
'''In the spare parts supply network, there are many uncertain factories, such as unpredictable demands and changeable lead times. The spare parts shortage caused by those uncertainties may lead to severe losses. To solve the uncertainty of supply network, a determined optimization model is developed and then reformulated as a robust counterpart. In the robust model, it is only necessary to know the moment information of the uncertain parameters rather than the true probability distribution. The solution obtained by the robust model can satisfy the constraints in the worst-case, that is, feasible for any probability distribution within the moment based ambiguity set. Two moment based robust models are studied in this work. The result of the experiment indicates that the robustness of the robust model is stronger than that of the determined model and chance constraint model, and the effect of safety tolerance on the robustness is revealed by sensitivity analysis. Finally, the second order moment model is verified be superior to the first order moment model in spare parts supply network optimization.
Abstract
'''In the spare parts supply network, there are many uncertain factories, such as unpredictable demands and changeable lead times. The spare parts shortage caused [...]
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Investigation on modeling and simulation BLDC motor fed universal actuation system
M. Murali, R. Arulmozhiyal

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 10

Abstract
This paper deals with mathematical modeling of Permanent magnet brushless DC (BLDC) motor in MATLAB-SIMULINK environment. Modeling of BLDC motor carried in transfer function, transfer equations and state space model to verify the performance as actuators. Mathematical switches to control electronic commutation of BLDC motor based on signals of Hall Effect position sensor using three-phase inverter drive. Performance of the simplified mathematical inverter fed BLDC motor under steady state and dynamic conditions analyzed. Due to the switching losses during PWM generation generates low ripple content in torque of BLDC motor which described and eliminated through state space model. Comparison made of proposed modeling of BLDC motor with motor parameters like back-EMF, stator current and speed of BLDC motor, proposed work suggests the state space modeling holds a superior method for design of BLDC motor during high dynamic load performance and operating ranges.
Abstract
This paper deals with mathematical modeling of Permanent magnet brushless DC (BLDC) motor in MATLAB-SIMULINK environment. Modeling of BLDC motor carried in [...]
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Blind source separation of rotor vibration signals in high-noise environments
Y. Jia, P. Xu, Z. Wang, P. Zong

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 8

Abstract
During the operation of the engine rotor, the vibration signal measured by the sensor is the mixed signal of each vibration source, and contains strong noise at the same time. In this paper, a new separation method for mixed vibration signals in strong noise environment (such as SNR=-5) is proposed. Firstly, the time-delay auto-correlation de-noising method is used to de-noise the mixed signals, and then one common algorithm (MSNR algorithm is used here) is adopted to separate the mixed vibration signals, which can improves the separation performance. The simulation results verify the validity of the method. The proposed method provides a new idea for health monitoring and fault diagnosis of engine rotor vibration signals.
Abstract
During the operation of the engine rotor, the vibration signal measured by the sensor is the mixed signal of each vibration source, and contains strong noise at the same time. [...]
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Analysis of short-circuit failures in synchronous machinery rotor using finite elements
E. Arrieta, N. Romero, M. Torregroza, I. Fuly

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 11

Abstract
In this paper, a mathematical model using finite element software is developed. An electromagnetic analysis is performed to determine the behavior of quantities such as magnetic flux density and output voltage when short-circuit failures occur in the winding of the rotor poles of a synchronous small size machine when it works as a generator. The voltage values obtained from the simulations were compared with data from actual tests performed in the laboratory.
Abstract
In this paper, a mathematical model using finite element software is developed. An electromagnetic analysis is performed to determine the behavior of quantities such as magnetic [...]
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Analysis of operability envelopes for subsea production tree installation
F. Wang, N. Chen, X. Deng, X. Ji, Q. Yang

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 3

Abstract
The article presents a mathematical model to investigate the operability envelopes for subsea production tress (SPT) installation using drill pipe. The finite differential method was used to solve the established governing equations in which the ocean conditions were considered. Based on the evaluations of the ocean wave, ocean current, water depth, specification of drill pipe and SPT weight that might dominate the mechanical behaviors of the pipe, the operability envelopes with permissible ocean conditions for SPT installation were obtained. The results indicate that changes of depths in deep water and SPT weight have few effects on the operation conditions and it would be better to choose smaller pipe to obtain larger permissible ocean conditions during SPT installation.
Abstract
The article presents a mathematical model to investigate the operability envelopes for subsea production tress (SPT) installation using drill pipe. The finite differential [...]
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Multi-body dynamics modeling and transient characteristics analysis for a folding wing
Y. NI, W. Zhang, Y. Lv

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 4

Abstract
The investigation of modeling the time evolution of a folding wing during the morphing process and the dynamic characteristics analysis is carried out. The governing equations with uniform form are developed from the integration of floating frame method in multi-body dynamics and component mode synthesis in structural dynamics. The time-dependent aerodynamic force is taken into the governing equations. The equation achieves the time-dependent coupling between structure and aerodynamics and avoids the data transmission and low efficiency, which holds true for the multi-segmented folding wing. The relative parameters in constraint equations are easily modified to be applied to both slow and fast-varying processes for a folding wing. Also, the influence of the velocity and attack angle on transient responses can be investigated. Transient response analysis shows that slower morphing means more stable transient responses. The flexibility of the folding wing has the significant influence on transient responses. To some extent, the aerodynamic force can be beneficial to the morphing process.
Abstract
The investigation of modeling the time evolution of a folding wing during the morphing process and the dynamic characteristics analysis is carried out. The governing equations [...]
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Evaluation of an accidental-torsion design proposal considering firm-soil ground motions
J. Zarza-González, J. De-la-Colina, J. Valdés-González

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 7

Abstract
Using non-linear analyses and Monte Carlo simulations, a simplified accidental-torsion design procedure is evaluated. The design procedure does not use an accidental eccentricity like the building codes do. For the evaluation, four reinforced concrete frame building models of four and seven stories are dynamically studied in the nonlinear range. The models are subjected to a set of five firm-soil, bidirectional seismic records. The design procedure is evaluated by comparing the ductility demands of both beams and columns for three conditions of each building model: a) the torsionally balanced model without accidental torsion (model TB), which establishes the reference values of ductility demands; b) the same nominal model but incorporating accidental torsion via the Monte Carlo method; and c) a model with amplified strength (model AS) according to the accidental-torsion design procedure to be evaluated. Results indicate that there is a probability smaller than 2.5% that accidental torsion can cause ductility demands approximately 20% to 25% larger than those of similar building models without accidental torsion. A comparison of ductility demands for the reference models without accidental torsion and those of models with accidental torsion and designed with the procedure that is evaluated, reveals that the design procedure is effective to control the effects of accidental torsion.
Abstract
Using non-linear analyses and Monte Carlo simulations, a simplified accidental-torsion design procedure is evaluated. The design procedure does not use an accidental eccentricity [...]
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Generalized finite difference solution for the Motz Problem
C. Chávez, F. Domínguez Mota, S. Lucas-Martinez, J. Tinoco-Ruiz, D. Santana Quinteros

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 13

Abstract
In this paper, it is presented a formulation of a generalized finite difference scheme to solve the Motz problem. It is based on a general difference scheme defined by an optimality condition, which has been developed to solve Poisson-like equations whose domains are approximated by a wide variety of grids over general regions. Numerical examples showing second-order accuracy of the calculated solutions are presented.
Abstract
In this paper, it is presented a formulation of a generalized finite difference scheme to solve the Motz problem. It is based on a general difference scheme defined by an [...]
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Siphon pipe parameter optimization of the toilet using CFD-DEM coupling method
Z. Li, X. Ge, K. Li, X. Tong

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 2

Abstract
The computational fluid dynamics (CFD) and discrete element method (DEM) coupling method is used to simulate the flushing process of the toilet and this paper analyzes the influence of different structural parameters of siphon pipe on the flushing performance of the toilet. And through the adjusted-parameters toilet, tlushing experments were carried out to verify the simulations. Meanwhile the orthogonal test of different structural parameters of siphon pipes were conducted to study the flushing Performance. The research results show that the CFD-DEM coupling method can be used to study the regularity of the toilet flushing performance. The toilet can get the better flushing performance when the tilt angle of the angle of inclination is 50°, the curvature width and length are 50 mm and 220 mm, the width and height of the secondary water seal are 100 mm and 25 mm and pipe diameter is 53 mm. The method in this paper can provide a new idea for the study and design of the flushing performance of the toilet.
Abstract
The computational fluid dynamics (CFD) and discrete element method (DEM) coupling method is used to simulate the flushing process of the toilet and this paper analyzes the [...]
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Approximation of the transport of pollutants with reaction terms in shallow waters using finite elements
A. Villota, R. Codina

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 6

Abstract
In this article we present the approximation of the coupled model of the equations of motion of a fluid in shallow waters with the convection-diffusion-reaction (CDR) equation of pollutant transport. This approximation is carried out using high order finite elements and using stabilised variational sub-scale methods. We write the coupled system of equations, previously discretised in time and linearised, as a transient vector equation of CDR. The stabilised finite element methods used are the known ASGS and OSS sub-scale methods, the same ones that allow us to use the same interpolation for all unknowns, as well as to deal with dominant convection and reaction flows. We consider the possibility of non-linearity in both the convective and reaction terms. We will not consider the possible development of shocks in the solution. In order to examine the accuracy and robustness of the ASGS and OSS methods, we present four test cases: mesh convergence, transport of a pollutant in a square cavity, transport of a pollutant in the Gulf of Roses and at the river Guadalquivir mouth, and the predator-prey model, which can be written as a transient CDR vector equation with non-linearity in the reaction term.
Abstract
In this article we present the approximation of the coupled model of the equations of motion of a fluid in shallow waters with the convection-diffusion-reaction (CDR) equation [...]
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Hydraulic modeling of combined sewers overflow integrating the results of the SWMM and CFX models.
D. Pulgarín, J. Plaza, J. Ruge, J. Rojas

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 14

Abstract
This study proposes a methodology for the calibration of combined sewer overflow (CSO), incorporating the results of the three-dimensional ANSYS CFX model in the SWMM one-dimensional model. The procedure consists of constructing calibration curves in ANSYS CFX that relate the input flow to the CSO with the overflow, to then incorporate them into the SWMM model. The results obtained show that the behavior of the flow over the crest of the overflow weir varies in space and time. Therefore, the flow of entry to the CSO and the flow of excesses maintain a non-linear relationship, contrary to the results obtained in the one-dimensional model. However, the uncertainty associated with the idealization of flow methodologies in one dimension is reduced under the SWMM model with kinematic wave conditions and simulating CSO from curves obtained in ANSYS CFX. The result obtained facilitates the calibration of combined sewer networks for permanent or non-permanent flow conditions, by means of the construction of curves in a three-dimensional model, especially when the information collected in situ is limited.
Abstract
This study proposes a methodology for the calibration of combined sewer overflow (CSO), incorporating the results of the three-dimensional ANSYS CFX model in the SWMM one-dimensional [...]
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Development of a refinement algorithm for tetrahedral finite elements
A. Hermosillo-Arteaga, M. Romo-Organista, R. Magaña del Toro, J. Carrera-Bolaños

Rev. int. métodos numér. cálc. diseño ing. (2021). Vol. 37, (1), 9

Abstract
Many of the engineering problems are analyzed using numerical methods such as the finite element (FEM) whose results provide a basis to make basic decisions regarding the design of many important works. accepted It is generally that FEM computations are reliable; however, the results may be affected by the definition of the finite element mesh, this is particularly true when the internal and external boundaries are time dependent, as is the case of soil consolidation. Accordingly, a thorough investigation was carried out with the main purpose of eliminating this inconvenience. The main steps to carried out the development of the innovative geometric procedure to automatically refine finite element tetrahedra-type (3D) are described. This geometric algorithm is based on the theory of fractals and is a generalization of the algorithm for triangular element finite element meshes (2D) [1, 2]. This paper presents the fundaments of this new algorithm and shows its great approximation using 3D close form solutions, and its versatility to adapt the original Finite Element Mesh when the load boundary conditions are modified (Neumann conditions).
Abstract
Many of the engineering problems are analyzed using numerical methods such as the finite element (FEM) whose results provide a basis to make basic decisions regarding the [...]
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