Scipedia: Documents published in 2017

Quantitative TEM tomography of Poly lactic acid/clay nanocomposites for a better comprehension of processing-microstructure-properties relationship

Scipedia content — Thu, 31 Mar 2022 14:58:40 +0200

The physicochemical properties of polymer nanocomposites (such as polymer/clay systems) are dependent on the properties of the polymer and filler, the reinforcement dimensionality, dispersion and orientation, and the nature of the interface between filler and matrix. Hence, thoroughly characterizing the morphology of those materials can lead to a better understanding of the behaviour of the final product and to improved design tools. The objective of performing TEM tomoghraphy (TEMT) on Poly lactic acid(PLA)/clay samples is to characterize their 3D microstructure, by obtaining the dispersion, distribution and orientation of the dimensions of the clays. This information cannot be elucidated from a qualitative TEM analysis or from conventional characterization techniques such as X-Ray diffraction. To carry out this work, nanocomposites obtained by extruding a PLA matrix and Cloisite 30B clays are used. The nanocomposites are obtained by using different extrusion shear rates. Shear rate favours the exfoliation of the clay particles and their dispersion, leading to nanocomposites with different microstructures and properties. Then, quantitative TEMT is performed to all the nanocomposites and the resulting 3D quantitative characterization is used for the comprehension of the mechanical behaviour of the nanocomposites.

Strategies in the analysis of samples of composites for the quantification of porosity by image analysis from optical microscopy

Scipedia content — Thu, 31 Mar 2022 14:58:30 +0200

Porosity and voids are a type of defect that may appear during the manufacturing of composite structures. Its possible presence is checked in production parts by different non-destructive techniques based on ultrasonic inspection. It is important to perform this evaluation considering that a high content of these defects decrease the mechanical properties compared to the original design. In recent years, optical microscopy of composite materials has become a very powerful tool, which is available for the industry to inspect and look at the internal structure and help to reach conclusions in the field of quality, failure analysis and I+D+I. In addition, the use of automatic scanning techniques of wide cross sections has opened the possibility of quantifying the percentage of porosity/voids, as well as become an alternative to more laborious testing procedures such as acid digestion of the resins. This study contributes to existing test standards within the aeronautical sector, in the sample preparation strategy. For this purpose, samples of epoxy matrices with carbon fibers, both unidirectional and fabric tapes have been analyzed to evaluate the influence of the quality of sample preparation, the stacking sequence and the initial porosity levels, the repeatability of the measurements and the quality of the results. An attempt has been made to correlate the results with standar physical / chemical analysis.

Test frame misalignment effect on CFRPs mechanical properties

Scipedia content — Thu, 31 Mar 2022 14:58:20 +0200

Traditionally, major aircraft manufacturers have shown great interest in ensuring a high degree of alignment in the load train of test machines that determine the mechanical properties of the CFRP materials being tested. This is manifested in the definition of stringent requirements as far as alignment is concerned in the actual testing regulations of these manufacturers, being the main reference standard ASTM E1012. This standard establishes different categories or classes, depending on the deformation recorded on a test piece instrumentalized with strain gauges. Specifically, the standard defines classes 5, 8 and 10, and it is common to establish class 5 for static tests on CFRPs, whereas these same tests on metallic materials usually require class 10. The present work aims to quantify the influence of the misalignment of the test frames on the mechanical properties of CFRPs subjected to static tensile testing (maximum tensile strength and modulus). In addition, the influence on the mechanical properties of the application of corrections of the test specimen has been studied when determining the degree of alignment based on the reference standard ASTM E1012. This last aspect is currently being studied by aeronautical manufacturers in the discussion forum of the NADCAP accreditation program, in its NMMT commodity. The present work shows the methodology used, as well as the results obtained for its discussion.

Analysis and optimization of coupon machinning for testing of adhesive shear resistance of joint bonded composite materials

Scipedia content — Thu, 31 Mar 2022 14:58:10 +0200

The quality control of bonded aerospace parts manufactured with carbon fiber it is based on the realization of tests according to standards being one of the most outstanding the test of slotted single lap shear strength of composite joints. In order to perform this mechanical test it is necessary to slot a semi-panel to reach the bonded line without damaging the second semi-panel. The process conditions to get the slot have a strong influence on the quality of results. The standard method is not exhaustive defining the most critical parameter such as the control of slot. Therefore, there is the need to perform and develop an investigation in order to study the influence of the slot on the tests results. This study is mainly focus on optimizing the slotting process of bonded joints in composite materials. For this purpose, both the behavior of the tool during machining and the influence of the cutting parameters have been studied, by analyzing the slot geometry, the repeatability in strength measurements, the quality of results and the failure modes. Always focusing on the quality and the optimization of the process. Finally, after optimizing the machining parameters the test results have been compared with the real values obtained from the single lap shear specimens without slots.

Pull-off tests of single T-stiffened specimens

Scipedia content — Thu, 31 Mar 2022 14:58:00 +0200

Results and conclusions of the analysis of a campaign of pull-off tests of single T-stiffened specimens are shown in this paper. The test intend to reproduce in a specimen the symmetrical local deformation shape that occurs in a stiffened panel during its postbuckling evolution. Four different groups have been considered combining two geometries and two stacking sequences for the skin and stringer. A total of 10 specimens have been tested. Tests were monitored with strain gauges. Visual inspections were performed during the process to detect the presence of debonding and/or delamination and to study the damage evolution. After the colapse, visual and microscopic analysis (optical and electronic) of the fracture surfaces were carried out. Inspections have shown the appearance of migrations of cracks from the skin-stiffening interface to delaminations between the first layers of the skin or vice versa. The effect that the different configurations of each specimen had on the onset and development of the damage has also been studied.

The analysis of mode decomposition in interlaminar fracture tests of asymmetric specimens

Scipedia content — Thu, 31 Mar 2022 14:57:50 +0200

Interlaminar failure tests are usually carried out in specimens where crack arms are symmetric. Asymmetric Double Cantiliver Beam (ADCB) is an exception where both crack arms have different thickness in order to get mixed mode I/II. The asymmetry in ADCB specimens could be applied also to te case of End Notched Flexure Tests, obtaining also mixed mode I/II. The decomposition proposed by Williams is not valid in the case of ADCB tests. On the other hand, articles related to asymmetric ENF tests including the mode decompositiion have not been found. The present study deals with the analsys of the mode decomposition in the case of specimens with asymmetric arms. The asymmetry may be related to the different thickness of the crack arms, to different materials or a combination of both factors. The results obtained will be compared with the results of mode decompsition that have been published in the case of ADCB tests.

Configuration of the ELS test for the determination of the mode II fracture toughness in adhesive joints

Scipedia content — Thu, 31 Mar 2022 14:57:40 +0200

In order to obtain Mode II fracture toughness of unidirectional fiber composite materials, the End-Loaded Split (ELS) has enjoyed great success because of its higher stability. As a result, crack growth initiation and propagation values are obtained, the latter being especially used in interlaminar progressive damage models. The propagation values must be obtained when the Failure Process Zone (FPZ) has completely developed. In delamination tests of unidirectional composites, such as those contemplated in ISO 15114, the dimension of the FPZ can be neglected against the rest of the dimensions of the specimen, whereby the self-similar crack growth is reached just after the initiation of the crack propagation. However, in adhesive joints, the dimension of the FPZ increases significantly due to the plasticity of the adhesives. And even it can be larger than the entire length reserved for crack propagation. When this occurs, only initiation values are obtained, always inferior to the values of propagation, being these values too conservative to reproduce the behaviour of the joint. In this paper we present a methodology to define the configuration of the ELS test and the specimen dimensions required to obtain propagation results in adhesive joints. The methodology defined is based on two criteria that take into account the length of the FPZ and the stability of the test. As a result, a domain of validity of the test is obtained, which, for a certain type of adhesive and specimen configuration, it indicated is there will be propagation or not.

Equivalent energy release rate and crack stability in the mixed-mode I/II ENFR test configuration

Scipedia content — Thu, 31 Mar 2022 14:57:30 +0200

Crack propagation performance in the ENFR (End Notched Flexure test with roller) test configuration is analyzed. The test configuration is based on the ENF test with a roller introduced between the two surfaces of the crack in order to get mixed-mode. Based on the reliability of the linear criterion, an equivalent energy release rate is proposed taking into account the interaction between the two modes and II. The stability of the crack propagation is defined by means of the derivative of the proposed equivalent energy release rate. Experimental tests with specimens of F593/T300 carbon/epoxy unidirectional composite have been carried out to assess the proposed equivalent energy release rate and to evaluate the crack stability condition. Finally, some recommendations for performing tests in the ENFR configuration under optimum conditions are summarized.

Analysis of the dcb test of angle-ply laminates including residual stresses

Scipedia content — Thu, 31 Mar 2022 14:57:19 +0200

The aim of the present study is the analytical determination of the energy release rate during the DCB test of angle-ply laminates. With this purpose, an analytic approach based on the complementary energy of a laminated beam including hygrothermal effects is proposed. These effects lead to initial strains that indeed, are impeded by the configuration of the DCB test. The consequent forces and moments are determined by means of Engesser-Castigliano theorem. Once these loads are known, an analytical expression for the energy release rate based on the complementary energy is obtained. Symmetrical and anti-symmetrical angle-ply laminates with 16 plies have been prepared and used for the tests. The configuration of the cracked arms is the same in both laminates, however, the delamination occurs between plies with different orientation. Experimental results of the energy release rate obtained by means of the area method agree with those determined by the proposed approach.

The three-point off-axis bending method for determining in-plane shear properties in wood

Scipedia content — Thu, 31 Mar 2022 14:57:10 +0200

Several methods to determine in-plane shear properties of anisotropic materials (i.e. fiber reinforced composite materials and natural wood) based on flexural loading have been proposed. One of those methods is the off-axis bending test that considers unidirectional composite materials subject to three-point bending (3-PB) loading. As a result of the anisotropic behaviour, unidirectional off-axis laminates subjected to flexure present a bending–twisting coupling that may cause, in the case of three-point bending loading, a lift-off of the specimen on the fixture supports. Such specimen lift-off has been considered one of the critical features to be considered on the mentioned experimental method. Besides, geometrical parameters and material elastic constants (i.e. longitudinal, transversal, and shear elastic moduli) influence the validity to use this method for characterizing in-plane shear properties. On that sense, an analytical approach for studying the material conditions for which the application of the off-axis 3-PB test is adequate to characterize natural wood is presented in this work. The condition of small displacements and the condition of lift-off between the specimen and the fixture supports have been taken into account. Some theoretical ideas regarding stress and displacement fields are also presented. The in-plane shear characterization has been performed on two natural wood species: Norway spruce (Picea abies) and beech (Fagus sylvatica). Test conditions for the off-axis 3-PB experimental bending test, in order to ensure its applicability, are presented.

Application of the Stiffness-Force method to the analysis of a plate in tension with a central hole

Scipedia content — Thu, 31 Mar 2022 14:56:59 +0200

In the formulation of the Stiffness-Force method (SFM) are taken into account the equilibrium equations and the compatibility conditions. These are obtained from the principles of virtual work and complementary virtual work. The structure of the governing equation of this method is similar to that of stiffness-method (SM) as the principal unknows are the displacements. This method is equivalent to IFMD formulated by Patnaik and to the hybrid methods formulated by Pian.For the Stiffness-Force method finite element analysis, a user subroutine UEL for a four node quadrilateral element has been developed. This subroutine has been implemented in the commercial program Abaqus. The procedure followed for the analysis of the model has been:1. Analysis of the model using the program Abaqus that employs the SM in its formulation.2. Analysis of the same model using the user subroutine UEL employing the SFM.3. Comparison of the results of both analysis, using varying degrees of discretization, to those obtained by an analytical approach.This procedure has been used in the analysis of the open-hole tensile strength test of a unidirectional composite.

Experimental study of non conventional interfaces with trapezoidal patterns.

Scipedia content — Thu, 31 Mar 2022 14:56:49 +0200

In the present investigation, double cantilever beam (DCB) specimens manufactured using 3D printing (ALM) are investigated from an experimental point of view. The influence of the aspect ratio A/λ (A = amplitude, λ = wavelength) in the fracture toughness of non-conventional interfaces is analysed, specifically for trapezoidal profiles. The particular geometry of the interface herein considered corresponds to that with the greatest ratio A/λ using the current technical capabilities of ALM (Additive Layer Manufacturing) devices. In the first part of the investigation, a preliminary analysis comprising the assessment of the applicability of different materials, which are supported by the 3D printer (nailon and glass-fiber-reinforced polymer composites), are shown in the manufacturing section. This first part of the study is analysed from different points of view: from non-conventional interfaces manufacturing of different typologies (to determine the printer accuracy) to the actual specimen manufacturing. In the laboratory test section, the set-up of the test and specimens before the laboratory test are described. The fracture toughness of conventional and structured interfaces, in particular with trapezoidal profiles, are compared.

Comparison of analysis between the classical ESIS method and the ASTM D-7905 standard, for obtaining shear fracture toughness

Scipedia content — Thu, 31 Mar 2022 14:56:40 +0200

The present work is part of the characterization of glass fiber composites elaborated with a novel vinylester-urethane resin, with addition of poly for use in reinforcing materials for concrete, as a passive reinforcement or as a reinforcement for structures in use, as these resins have a higher Resistance to chemical agents, basics and vapors along with a lower exotherm facilitating the manufacture of thick laminates.Within Mode II fracture mechanics, until this 2014 there was no standard that would collect a procedure to quantify GIIC. Davies through the European Structural Integrity Society (ESIS) issued a mode II test protocol in 1992 known as ENF (End Notch Flexure) [1]ASTM D7905-14 encompasses a fairly complex procedure in which the basis for the characterization of shear fracture toughness in mode II using the final notch flexure (ENF) test is laid.This paper aims to verify the main differences between this classical procedure and the method of this standard to verify their similarities.For this purpose, a mechanical pre-characterization of the reinforced resin is carried out with high-grade fabric (780 g/cm2) with glass fiber E as well as a thinner carbon fiber composite. This characterization is performed by ENF bending tests, and the procedure of the new ASTM D-7905 standard. [1] ASTM D5528-01, “Standard Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites”, American Society for Testing and Materials, 2001.

Flaw-Bridging in Composite Materials

Scipedia content — Thu, 31 Mar 2022 14:56:33 +0200

The implicit assumption in the modelling of fibre reinforced materials is that they are defect free. Defects in fibre-reinforced materials can be initated during their service life and can result a variety of damage phenomena. This paper focuses on the mathematical treatment of the case where a defect is present in the matrix of a uni-directionally reinforced composite but the fibres themselves exhibit continuity across the matrix crack. This results in a processes that is referred to as “flaw bridging”. The amplification of the stress intensity factors at the boundary of the matrix crack can be influenced by the bridging action, to the extent that if the the fibres are inextensible, the stress intensity factor can be suppressed. This paper examines the flaw bridging action in a unidirectionally reinforced composite, which can be reduced to the solution of a Fredholm integral equation of the second kind. The mathematical treatment is used to examine the influence of the bridging action on the crack opening mode stress intensity factors at the boundary of a penny-shaped crack.

Characterization of the fracture toughness of composite materials by infrared thermography

Scipedia content — Thu, 31 Mar 2022 14:56:18 +0200

An experimental procedure has been developed to characterize the interlaminar resistance of composite materials, specifically prepregs of vinylester-epoxy nature, based on the determination of their critical energy by the realization of consecutive low energy impacts on test specimens of the studied material.The impact sequence was performed by means of a certified impactor, based on a pendulum system, and the system used to measure the integrity of the material after each impact consisted in the NDT optical pulsed thermographic technique. In the present study, a series of 8 specimens made of unidirectional glass fiber with different arrangements and specific treatments, both on the reinforcement and the resin matrix itself, were used to carry out its characterization, as it is an asymmetric fabric based on a surface of continuous fibers and the other surface with glass veil finish. The NDT technique used has enabled, on the one hand, to quickly and efficiently identify the breakage of the materials and to determine the critical energy, and on the other hand, it has made possible to precisely measure the area of the delaminated zones and to determine their localization in depth through the graphic representation by means of projection in RGB channels.The results obtained in the characterization using the proposed procedure have been validated with fracture energy tests in mode I and II, obtaining satisfactory levels of correlation between both procedures.

Experimental observations of interface cracks associated with compression matrix failure in composite laminates

Scipedia content — Thu, 31 Mar 2022 14:56:08 +0200

Matrix/Inter-fibre failure is characterized by the appearance at the fiber-matrix interfaces of small debonds that can progress along them until reaching a certain extension, then, changing their orientation kinking towards the matrix and finally growing through it. The particular case of compressive loading is specially interesting, given the morphology of the interface cracks and the specific angle that the macrocracks form in the matrix.To date, the analysis of this problem at micromechanical level has been carried out mainly by means of Finite Element or Boundary Element models. In this work, the problem is approached from the experimental point of view, observing under the microscope specimens previously tested at different loading levels. Several aspects such as the identification of the phases of the faliure mechanism, the kinking angle, the extension of the interface cracks and the presence of damage as a function of the loading level are studied.

Effect of ply-thickness on the impact response of interleaved thin-ply non-crimp-fabric laminates: X-ray tomography investigation

Scipedia content — Thu, 31 Mar 2022 14:55:56 +0200

Composite laminates subjected to out-of-plane loads develop damage modes that compromise the load-carrying capacity, as in the fuselage skin of an aircraft. Therefore, we aimed to improve the damage resistance and tolerance of carbon/epoxy thin non-crimp fabric (NCF) laminates by (a) reducing the ‘conventional’ ply-thickness (i.e. comparing thick- and thin-plies) (b) interleaving co-polyamide (CoPA) non-woven veils at the interlaminar regions of thin-ply systems. We devised an impact, compression after impact (CAI) and quasi-static indentation (QSI) experimental campaign, where computerized X-ray tomography provided detailed 3D insight on how matrix cracking, delamination and fibre failure interacted during impact and QSI. Thin-ply laminates reduce the amount of matrix cracking and delamination at the cost of premature fibre breakage, therefore decreasing the damage tolerance. Interleaving CoPA veils arrests delamination onset and improves the residual strength with respect to the thin-ply baseline. [1] S.Sihn, R.Y. Kim, K.Kawabe and S.W. Tsai, Compos. Sci. Technol., vol. 67, no. 6, pp. 996–1008 (2007). https://doi.org/10.1016/j.compscitech.2006.06.008[2] V.A.Ramirez, P.J.Hogg and W.W.Sampson, Compos. Sci. Technol., vol. 110, pp. 103–110 (2015). https://doi.org/10.1016/j.compscitech.2015.01.016

Damage Tolerance of CFRP laminates subjected to CAI after low velocity impact

Scipedia content — Thu, 31 Mar 2022 14:55:47 +0200

Primary structures fabricated with carbon/epoxy pre-impregnates has become very popular, especially in aeronautics and automotion. Despite the excellent properties of resistance and stiffness, composite materials present a high sensitivity to impact damage which can cause a sudden drop of mechanical properties affecting the service behavior and reducing the useful life. Here is where damage tolerance concept is introduced.In this work, firstly impact tests have been made in composite lamintes reinforced with carbon fiber, and then, the residual strength for the different stacking sequences have been evaluated using CAI (Compression After Impact) tests.

Effects of laminate thickness and ply-stacking sequence on the low velocity impact resistance of carbon fiber-reinforced laminates

Scipedia content — Thu, 31 Mar 2022 14:54:51 +0200

Carbon/epoxy pre-impregnated has become one of the most demanded materials for some aeronautics structures. Boeing 787 and Airbus A350 are pioneers in incorporating carbon fiber-reinforced composite materials in primary structures as wings and airframe. Tailoring the laminate ply sequence involves a difficult challenge owing to the rigorous design and operational criteria. Given that composite materials present a high sensitivity to impact loads, it has been indispensable to examine the influence of different factors in the failure mechanisms after an impact event. In this work, the effect of impact energy, stacking sequence and thickness on the impact damage resistance of CFRP composites was investigated. Damage response parameters as peak force, absorbed energy and delamination threshold were obtained from the impact curves. Then, a C-Scan imagen showed the damage extension using the non-destructive inspection Phased Array.

Validation of a numeric approach for modelling delamination damage caused by low energy impact

Scipedia content — Thu, 31 Mar 2022 14:54:40 +0200

A numerical approach has been developed for modelling the behaviour of a carbon fibre woven laminate under low-level energy impact. The model results have been compared with dart drop tests under sub and supercritical impact energies in fibre carbon textile laminates of different thickness.The models were developed using Ls-Dyna explicit finite element code. The validation approach was based in increasingly complexity approach. First models were developed and compared with subcritical impact energy test. Afterwards, supercritical impact energy has been applied in the laminates and delamination failure has been considered. In order to model delamination damage, cohesive law has been applied using Ls-Dyna cohesive and contact elements. The validation of the model has been carried out by comparing force and displacements.

Simulation of impacts on plates made of composite material

Scipedia content — Thu, 31 Mar 2022 14:54:29 +0200

The paper describes in some detail the difficulties encountered when conducting simulations intended to be realistic, and hence useful from a predictive viewpoint, of localised impact events on composite shells.Experimental results of drop tower tests were available on this occasion, consisting of an impactor with semi-spherical end being dropped from various heights onto a square shell made of composite material.The exhaustive simulations performed included different constitutive behaviours of the material, damage models, element types, and simulation strategies (three-dimensional and axially symmetric).The results show that, as the damage level increases, the problem becomes very complex because it requires capturing well the onset of interlaminar failures, as well as reproducing accurately the transition from a bending to a membrane resisting mechanism, which is what happens as those failures accumulate. The best results were obtained using very refined meshes, with four levels of elements per layer, and with cohesive elements between adjacent layers.Apart from the difficulties posed by the numerical simulation, it is worth pointing out that the study of these problems also tends to suffer because the characterisation of the parameters and properties governing the material behaviour is often less precise and reliable than desirable.

Open letter from AEMAC presidents

Scipedia content — Thu, 31 Mar 2022 14:54:19 +0200

Los abajo firmantes compartimos una firme convicción en el papel que la Asociación Española de Materiales Compuestos, AEMAC, debe desempeñar como aglutinador y difusor de información relacionada con la innovación y la aplicación de los materiales compuestos. La asociación, como toda entidad viviente, sólo puede tener la capacidad de realizar sus funciones si cuenta con unos mecanismos que faciliten las relaciones internas y con el exterior. Es en este sentido que dar a luz una revista científico-técnica sobre materiales compuestos nos enorgullece y llena de optimismo.La aparición de esta revista es el resultado de un proceso de maduración que inició el expresidente Alfredo Güemes hace ya unos años. Desde la mención del interés de crearla a consolidar la plataforma informática para alojarla, convencer a los miembros del consejo editorial y llegar a este primer número, se han vertido muchos esfuerzos y vencido muchas inercias. Han sido muchas las personas implicadas a las que es de ley mostrar nuestro sincero agradecimiento en nombre de AEMAC.La revista Materiales Compuestos es ahora un recién nacido. Su futuro es prometedor a la vista de la calidad y actividad científica de los grupos de investigación que conforman AEMAC, pero cuál será su implantación y aceptación en la comunidad hispanohablante del sector dependerá de varios factores: desde el empeño y dedicación de los editores y el consejo editorial hasta el mismo progreso que tenga la investigación en materiales compuestos en España e Iberoamérica. La imaginación sobre el futuro de esta criatura nos lleva a una revista reconocida internacionalmente, con un flujo de manuscritos que permita la publicación periódica de sus números, con ediciones temáticas especiales dirigidas por editores de prestigio, con números especiales de congresos relevantes, indexada en distintas bases de datos… Sólo el tiempo lo confirmará.

Análisis de placas sándwich con pieles de material compuesto sometidas a impacto oblicuo de alta velocidad

Scipedia content — Thu, 31 Mar 2022 14:54:09 +0200

In this work, the oblique impact response of sandwich structures, with carbon/epoxy face-sheets and aluminium honeycomb core, is analysed by implementing a 3D numerical model in Abaqus/Explicit finite element code. The numerical model was validated with data taken from the scientific literature for a normal impact, and numerical results showed good correlation with experimental data. The validated model was used to study the variation of the ballistic limit and the residual velocity with the impact angle of the projectile. In order to determine the contribution of the core in the impact process, another finite element model was developed, corresponding to that of a laminated spaced plates a distance equivalent to the thickness of the composite sandwich core. It was found that both ballistic limit values and residual velocity are affected by the presence of the core in the sandwich plates and by the obliquity of the impact angle.

Editorial

Scipedia content — Thu, 31 Mar 2022 14:54:00 +0200

Con este número inaugural de "Materiales Compuestos" damos comienzo a un nuevo proyecto surgido dentro de la Asociación Española de Materiales Compuestos (AEMAC). Esta revista quiere ser un punto de encuentro entre investigadores, desarrolladores, técnicos, ingenieros, científicos y, en definitiva, todos aquellos profesionales que desarrollen su actividad en el mundo de los materiales compuestos.
Esta nueva revista está dedicada a la publicación de trabajos de investigación enfocados a obtener una mayor comprensión de estos materiales y su incidencia en el sector industrial en general. Así, y dado el carácter interdisciplinar de la investigación desarrollada en este campo, en esta revista tienen cabida artículos de todas las áreas involucradas en estos materiales, como por ejemplo la química, la física, la ciencia de materiales o las ingenierías.
El lanzamiento de “Materiales Compuestos” ha sido posible gracias al esfuerzo de muchas personas. En primer lugar, queremos agradecer a Josep Costa, que tomó el testigo del expresidente Alfredo Güemes, por poner en marcha y cimentar las bases de esta revista. También debemos agradecer al actual presidente, Jacinto Tortosa, por su apoyo y entusiasmo por sacar adelante este número. También queremos agradecer a Helena Abril su ayuda y su disponibilidad. Por último, agrademos a los miembros del Consejo Editorial por embarcarse con nosotros en esta nueva empresa.
Como editores, nos enorgullece formar parte de este nuevo desafío, agradeciendo también a las Juntas Directivas la confianza depositada en nosotros para sacar adelante este nuevo proyecto de la Asociación.

Evaluation of the energy absorption and the damage on woven laminates subjeted to high-velocity impacts

Scipedia content — Thu, 31 Mar 2022 14:51:17 +0200

In this work, it was evaluated the behaviour of monolithic structures made of woven laminae of E-glass/polyester.subjected to high-velocity impacts, through experimental techniques. It were studied four monolithic laminates of different thicknesses:3, 6, 9 and 12 mm, evaluating the energy absorption, the contact time between the plate and the projectile during the impact event and the extension of damaged area in both faces of the laminate, through non-destructive inspection techniques. Once the results were obtained, It was found that laminates of greater thickness show a larger damage area for both faces of laminate, greater contact time .and, minumun perforation-energy.

Evaluation of Stock Management Strategies Reliability at Dependent Demand

Scipedia content — Tue, 23 Mar 2021 06:43:42 +0100

"jats:p"For efficiently increasing the logistic systems, the core specialists’ attention has to be directed to reducing costs and increasing supply chains reliability. A decent attention to costs reduction has already been paid, so it can be stated that in this way there is a significant progress. But the problem of reliability evaluation is still insufficiently explored, particularly, in such an important sphere as inventory management at the dependent demand."/jats:p" "jats:p"In the article there is a suggested methodical approach that allows calculating the safety stock quantity at the dependent demand in view of supply chains reliability requirements; the variants for different inventory management strategies at the dependent demand are examined; optimal strategy choice algorithm and results of total costs calculation in view of the reliability are given.

Document type: Article

Recommendations for actions concerning supporting ITS developments for VRUs

Scipedia content — Tue, 23 Mar 2021 06:41:23 +0100

Introduction: This paper presents some of the work conducted in FP7 VRUITS project to draw a set of general recommendations for actions at the EU level aiming to enhance the deployment of ITS systems directed to improve the safety, mobility and comfort of vulnerable road users. Method: The work started by identifying potential barriers, as well as recommendations to overcome these barriers. After that, similar recommendations were combined and prioritised, which are discussed via a workshop and questionnaire. In addition, a qualitative analysis was used to select thirteen main recommendations, for which a quantitative Benefit Analyses and a Multi-Criteria analysis were conducted. Results: In total, over 200 barriers and recommendations were identified for the 10 selected ITS systems. After several steps 13 main general recommendations were selected and ranked according to priority. Conclusions: 1) A wide range of different type of measures directed to different stakeholders is needed 2) Focus should be on facilitating the implementation of the 13 main recommendations, 3) Benefits of implementation of the recommendations can be in the order of billion(s) of euros, and 4) Main challenges are achieving cooperation between the different stakeholders, the different environments, the long time horizon for implementation and the high implementation costs. © 2017, The Author(s).

Document type: Article

Information Dynamics in Transportation Systems with Traffic Lights Control

Scipedia content — Tue, 23 Mar 2021 06:26:36 +0100

Due to recent advanced communication possibilities between traffic infrastructure, vehicles and drivers, the optimization of traffic lights control can be approached in novel ways. At the same time, this may introduce new unexpected dynamics in transportation systems. The authors' research aims to determine how drivers and traffic lights systems interact and influence each other when they are informed one about another's behaviour. In order to study this, the authors developed an agent based model to simulate transportation systems with static and dynamic traffic lights and drivers using information about the traffic lights behaviour. Experiments reveal that the system's performance improves when a bigger share of drivers receive information for both static and dynamic traffic lights systems. This performance improvement is due to drivers managing to avoid stopping at red light rather them adapting their speed to different distances to the traffic lights systems. Additionally, it is demonstrated that the duration of the fixed phases also influences the performance when drivers use speed recommendations. Moreover, the results show that dynamic traffic lights can produce positive effects for roads with high speed limits and high traffic intensity, while in the rest of the cases static control is better. The findings can be used for building more efficient traffic lights systems.

Document type: Article

Methods for evaluation of mechanical stress condition of materials

Scipedia content — Tue, 23 Mar 2021 05:54:11 +0100

Primary attention is given to the following methods: method by drilling cylindrical holes (drill method) and integrated ultrasonic method using volume (longitudinal and transverse), surface, and sub-surface waves. Drill method allows determination of residual mechanical stress in small depth of material surfaces, assessing type, size, and orientation of principal stresses. For the first time, parallel studies are carried out of mechanical stress in materials using the electroacoustic effect of volume, surface and sub-surface waves on the one hand, and effective mechanical stresses on the other. The experimental results present electroacoustic coefficients for different types of waves in the material of gas pipeline tube of 243 mm diameter and 14 mm thickness. These are used to evaluate mechanical stresses in pipelines, according to active GOST standards.

Document type: Article

A Local Spatial Analysis Criterion of Post-Traumatic Brain Injury and Accessibility to Public Transportation

Scipedia content — Tue, 23 Mar 2021 05:52:01 +0100

Reported cases of traumatic brain injuries are increasing among the Canadian population. With an annual rate of 187,000 reported cases a year and growing, there is an extrapolated growth of 239,000 cases of traumatic brain injuries occurring annually by 2036. As Ontario intends to be a completely accessible province for those with disabilities by 2025, this paper utilizes GIS to visualize and better understand the relationship between post- TBI residents living in Brampton and their accessibility to public transportation. As Brampton is currently the most expensive city to insure a vehicle because of frequent collisions occurring within the city, creating a more accessible, reliable, and efficient public transportation system can integrate those who have experienced a traumatic brain injury back into society while reducing the required use of a personal vehicle. This will contribute to a safer city, as there are fewer vehicles on the road at risk of being involved in a road accident. There are also further benefits to this, as it will also reduce levels of congestion in the foreseeable future. info:eu-repo/semantics/publishedVersion

Document type: Article

Automated software for hydraulic simulation of pipeline operation

Scipedia content — Tue, 23 Mar 2021 05:35:43 +0100

Design of modern water supply systems of large cities as well as their management via renovation of hydraulic models poses time-consuming tasks to researchers, and coping with this task requires specific approaches. When tackling these tasks, water services companies come across a lot of information about various objects of water infrastructure, the majority of which is located underground. In those cases, modern computer-aided design systems containing various components come to help. These systems help to solve a wide array of problems using existing information regarding pipelines, analysis and optimization of their basic parameters. CAD software is becoming an integral part of water supply systems management in large cities, and its capabilities allow engineering and operating companies to not only collect all the necessary data concerning water supply systems in any given city, but also to conduct research aimed at improving various parameters of these systems, including optimization of their hydraulic properties which directly determine the quality of water. This paper contains the analysis of automated CAD software for hydraulic design and management of city water supply systems in order to provide safe and efficient operation of these water supply systems. Authors select the most suitable software that might be used to provide hydraulic compatibility of old and new sections of water supply ring mains after selective or continuous draw-in renovation and decrease in diameter of distribution networks against the background of water consumption decrease in the cities.

Document type: Article

Simplified Ultrasonic Damage Detection in Fluid-Filled Pipes

Scipedia content — Tue, 23 Mar 2021 05:25:56 +0100

The location and extent of damage in a pipe can be remotely determined from weld and internal damage reflections using a single acoustic emitter/sensor pair. The use of normalised reflections yields single numbers enabling long distance data collection techniques such as wireless hopping. The attenuation is twice as high for opposite inner and outer fluids (whether air and water, or water and air) as compared to identical inner and outer fluids. The absolute recorded signals in the water-filled pipe are attenuated by a factor two compared to the empty pipe. The axial length of detection is reduced by a half. The reduction of "90% in sensors and the longer axial detection ("10\\(\\times \\) current state-of- the-art- technology) means that permanent fixed sensor pairs for whole pipelines are on the horizon of possibility. The greatest advantage is envisioned in submersed pipelines.

Document type: Article

New Training Schemes for The Future Education in Railway Sector

Scipedia content — Tue, 23 Mar 2021 05:23:35 +0100

Railway transport is a sector that is rapidly developing, changing and being influenced to the maximum extent by the technological development and innovation, among others, thus facing problems in staffing its several domains with appropriate and qualified personnel. This fact, makes the need for changes in training and education of future transport professionals. SKILLFUL project vision is to identify the skills and competences needed by the transport workforce of the future and define the training methods and tools to meet them. Paper focuses on mid-term results of the project, with special focus on railway transport.

Document type: Article

CFD Simulation of Pipeline Transport Properties of Mine Tailings Three-Phase Foam Slurry Backfill

Scipedia content — Tue, 23 Mar 2021 04:30:27 +0100

three-dimensional backfill pipeline transport model is developed using the computational fluid dynamics (CFD) technique, which is applied to study the pipeline transport properties of three-phase foam slurry backfill (TFSB). Based on rheological property tests and CFD simulations, the foam phase, pressure, and velocity in the pipeline system are investigated using the CFD mixture method for different bubble volume fractions and bubble diameters. The simulation results indicate that TFSB can maintain a steady state during pipeline transport, experience a markedly reduced pipeline transport resistance, and exhibit better liquidity than conventional cement slurry. Furthermore, as the bubble volume fraction increases, the resistance of the pipeline decreases and the fluidity improves. By contrast, the bubble diameter has little effect on the transport properties of TFSB. The combined results of CFD simulations, slump tests, and strength tests indicate that, when the bubble volume fraction is 15–20 vol %, TFSB can satisfy the necessary strength requirements and exhibit self-flowing transport. The CFD technique provides an intuitive and accurate basis for pipeline transport research and has the potential for wider application in studies of mine backfill.

Document type: Article

Investigation of the motion processes of wastewater in sewerage of high-rise buildings

Scipedia content — Tue, 23 Mar 2021 04:20:40 +0100

When designing, constructing and operating sewage pipelines in high-rise buildings, issues of failure-free operation of a network arise. Investigation of the processes of wastewater moving allows identifying problem areas during operation, assessing the possibility of obstructions and breakdowns of plumbing traps on the gravity drainage sections of the pipeline. The article performs the schemes of the water outflow from the floor sewer into the riser, including the places where the riser is bent, of air delivery to the working riser under the change of the direction of drain movement with the dropout line set-up, with the installation of an automatic anti-vacuum valve, with the installation of the ventilation pipeline. Investigations of the process of sewage waste flow in a sewage riser were carried out, in order to select the appropriate structure. The authors consider structure features of some sections of sewerage in high-rise buildings. The exhaustion value in the riser is determined from the rarefactions that occur below the compressed cross-section of the riser and the loss of the air flow pressure coming from the atmosphere into the riser during the deflooding of the liquid. Preventing the formation of obstructions and breakdowns of plumbing traps is an integral part of sewage networks.

Document type: Article

A Novel Method for Predicting Vehicle State in Internet of Vehicles

Scipedia content — Tue, 23 Mar 2021 04:18:30 +0100

In the fields of advanced driver assistance systems (ADAS) and Internet of Vehicles (IoV), predicting the vehicle state is essential, including the ego vehicle’s position, velocity, and acceleration. In ADAS, an early position prediction helps to avoid traffic accidents. In IoV, the vehicle state prediction is essential for the required calculation of the expected reliable communication time between two vehicles. Many approaches have emerged to perform this vehicle state prediction. However, such approaches consider limited information of the ego vehicle and its surroundings, and they may not be very effective in practice because the real situation is highly complex and complicated. Moreover, some of the approaches often lead to a delayed prediction time due to collecting and calculating the substantial history information. By assuming that the driver is a robot driver, which eliminates distinct driving behaviors of different persons when facing the same situation, this paper creates a decision tree as a new quick and reliable method adapted to all road segments, and it proposes a new method to perform the vehicle state prediction based on this decision tree.

Document type: Article

Using Latent Semantic Analysis to Identify Research Trends in OpenStreetMap

Scipedia content — Tue, 23 Mar 2021 03:50:46 +0100

OpenStreetMap (OSM), based on collaborative mapping, has become a subject of great interest to the academic community, resulting in a considerable body of literature produced by many researchers. In this paper, we use Latent Semantic Analysis (LSA) to help identify the emerging research trends in OSM. An extensive corpus of 485 academic abstracts of papers published during the period 2007–2016 was used. Five core research areas and fifty research trends were identified in this study. In addition, potential future research directions have been provided to aid geospatial information scientists, technologists and researchers in undertaking future OSM research.

Document type: Article

Differential Evaluation of Crew Functional Effectiveness

Scipedia content — Tue, 23 Mar 2021 03:41:25 +0100

"jats:p"The aim of this article is the development of the system and methodology of complex control and evaluation of vehicle operators performance during multifunctional simulation. In order to achieve the above-stated aim it is necessary to solve the following principal tasks: to elaborate a theoretical model of differentiated evaluation of vehicle operator training degree according to different kinds of their functional performance; to develop the method of the differential evaluation of crew performance on full-scale aviation simulators with due consideration of the probabilistic approach on the basis of statistical processing of the data of recorded flight information. The offered theoretical model of the differential evaluation of operator performance and the methodology of standards determination developed on its basis represent a new approach to the creation of automated systems for the objective evaluation of the trainees’ qualification degree. The elaborated system of differential evaluation standards ensures a high degree of objectiveness when evaluating the degree of the vehicle operator qualification and makes it possible to carry out a comparative analysis of the operators’ qualification.

Document type: Article

A Survey on PEV Charging Infrastructure: Impact Assessment and Planning

Scipedia content — Tue, 23 Mar 2021 03:23:36 +0100

Plug-in electric vehicles (PEVs) represent a huge step forward in a green transportation system, contribute in reduction of greenhouse gas emission, and reduce the dependence on fossil fuel. Integration of PEVs into the electric power system will result in a considerable addition to electricity demand. Due to PEV mobility, this demand has a random distribution in space and time among distribution system nodes. Therefore, short term forecast of PEV charging demand is more challenging than that for conventional loads. Assessment of PEV impacts on the power system is essential to mitigate the impairments from PEV loads. Optimal planning of PEV charging infrastructure will promote the penetration rate of PEVs and minimize the negative impacts of PEVs on the electric power distribution system and transportation road network. Design of charging facilities with integrated distributed energy resources (DER) is considered a solution to alleviate strain on the grid, reduce the integration cost with the distribution network and the charging cost. In this paper, we present a comprehensive literature survey on modelling of PEV charging demand, impact assessment approaches and tools, and charging infrastructure planning. Moreover, an overview on charging facility design with integrated DER is given. Some future research directions are identified.

Document type: Article

A multifunctional battery module design for electric vehicle

Scipedia content — Tue, 23 Mar 2021 03:12:42 +0100

Reducing the overall vehicle weight is an efficient, system-level approach to increase the drive range of electric vehicle, for which structural parts in auto-frame may be replaced by battery modules. Such battery modules must be structurally functional, e.g., energy absorbing, while the battery cells are not necessarily loading–carrying. We designed and tested a butterfly-shaped battery module of prismatic cells, which could self-unfold when subjected to a compressive loading. Angle guides and frictionless joints were employed to facilitate the large deformation. Desired resistance to external loading was offered by additional energy absorption elements. The battery-module behavior and the battery-cell performance were controlled separately. Numerical simulation verified the experimental results.

Document type: Article

Analytical Modeling Tool for Design of Hydrocarbon Sensitive Optical Fibers

Scipedia content — Tue, 23 Mar 2021 03:03:53 +0100

Pipelines are the main transportation means for oil and gas products across large distances. Due to the severe conditions they operate in, they are regularly inspected using conventional Pipeline Inspection Gages (PIGs) for corrosion damage. The motivation for researching a real-time distributed monitoring solution arose to mitigate costs and provide a proactive indication of potential failures. Fiber optic sensors with polymer claddings provide a means of detecting contact with hydrocarbons. By coating the fibers with a layer of metal similar in composition to that of the parent pipeline, corrosion of this coating may be detected when the polymer cladding underneath is exposed to the surrounding hydrocarbons contained within the pipeline. A Refractive Index (RI) change occurs in the polymer cladding causing a loss in intensity of a traveling light pulse due to a reduction in the fiber’s modal capacity. Intensity losses may be detected using Optical Time Domain Reflectometry (OTDR) while pinpointing the spatial location of the contact via time delay calculations of the back-scattered pulses. This work presents a theoretical model for the above sensing solution to provide a design tool for the fiber optic cable in the context of hydrocarbon sensing following corrosion of an external metal coating. Results are verified against the experimental data published in the literature.

Document type: Article

Method for Determining Volumetric Efficiency and Its Experimental Validation

Scipedia content — Tue, 23 Mar 2021 02:57:27 +0100

"jats:p"Modern means of transport are basically powered by piston internal combustion engines. Increasingly rigorous demands are placed on IC engines in order to minimise the detrimental impact they have on the natural environment. That stimulates the development of research on piston internal combustion engines. The research involves experimental and theoretical investigations carried out using computer technologies. While being filled, the cylinder is considered to be an open thermodynamic system, in which non-stationary processes occur. To make calculations of thermodynamic parameters of the engine operating cycle, based on the comparison of cycles, it is necessary to know the mean constant value of cylinder pressure throughout this process. Because of the character of in-cylinder pressure pattern and difficulties in pressure experimental determination, in the present paper, a novel method for the determination of this quantity was presented. In the new approach, the iteration method was used. In the method developed for determining the volumetric efficiency, the following equations were employed: the law of conservation of the amount of substance, the first law of thermodynamics for open system, dependences for changes in the cylinder volume vs. the crankshaft rotation angle, and the state equation. The results of calculations performed with this method were validated by means of experimental investigations carried out for a selected engine at the engine test bench. A satisfactory congruence of computational and experimental results as regards determining the volumetric efficiency was obtained. The method for determining the volumetric efficiency presented in the paper can be used to investigate the processes taking place in the cylinder of an IC engine.

Document type: Article

Expanding the Possibilities of AIS Data with Heuristics

Scipedia content — Tue, 23 Mar 2021 02:49:27 +0100

utomatic Identification System (AIS) is primarily used as a tracking system for ships, but with the launch of satellites to collect these data, new and previously untested possibilities are emerging. This paper presents the development of heuristics for establishing the specific ship type using information retrieved from AIS data alone. These heuristics expand the possibilities of AIS data, as the specific ship type is vital for several transportation research cases, such as emission analyses of ship traffic and studies on slow steaming. The presented method for developing heuristics can be used for a wider range of vessels. These heuristics may form the basis of large-scale studies on ship traffic using AIS data when it is not feasible or desirable to use commercial ship data registers. The Transnav - International Journal on Marine Navigation and Safety of Sea Transportation articles are distributed under the terms of the Creative Commons Attribution License (CC BY-NC), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. For licence details please see http://creativecommons.org/licenses/by-nc/3.0

Document type: Article

Process analysis transit of municipal waste. Part I - International provisions of law

Scipedia content — Tue, 23 Mar 2021 02:45:28 +0100

"jats:p" One of the crucial reasons of the system changes of waste management in our legal system in Poland was a need to implement solutions and mechanisms that are applied in the European Union. At the European Union law level, a Directive 2008/98/EC of the European Parliament and of the Council of 19 November 2008 on waste and repealing certain Directives constitutes a basic legal document described in this part of the article. The essential idea of the quoted directive is creating legal measures, promotion of eliminating waste production and treating it as a source instead. Achievement of these assumptions requires providing segregation at source and recycling of the main waste streams above all. It is necessary to encourage this action and support the reuse of products and waste utilization. Indicated international legal instruments are of primary importance for internal rules, which shall be constructed in a way that enables the achievement of goals determined by the EU law. Legal-organizational internal systems associated with the management of waste have undergone substantial changes from 2010. National legal provisions will be presented in the second part of the article.

Document type: Article

Investigating the effect of weather on punctuality of Norwegian railways: a case study of the Nordland Line

Scipedia content — Tue, 23 Mar 2021 02:37:49 +0100

The overall punctuality of the railway system is of particular importance for customers in order to use trains as a means of public transport. Investigating the drivers of low punctuality of trains is an essential step for improving their punctuality. Severe weather conditions are assumed to be one of the drivers of delays and low punctuality of the transportation system. This paper addresses the extent to which the weather factors such as temperature, snow, precipitation and wind influence the punctuality of trains on the Norwegian railways. The data for the study are collected from the passenger trains on the Nordland Line. The study period is 10 years, from the beginning of 2007 to the end of 2016. Data are analysed on a daily and weekly basis, and correlation and regression analyses are used to perform the statistical analysis. The results show that extreme cold weather during the winters is a crucial influencing factor contributing to delays and low punctuality. We also found that the weather variable that best explains variations in punctuality of passenger trains on this line is snow depth. © The Author(s) 2018 Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/)

Document type: Article

Assessment of the Capacity of Roads Weaving Segments

Scipedia content — Tue, 23 Mar 2021 02:22:41 +0100

"jats:p" Driving style is affected by development of cars and it has influence on the capacity of designed elements of roads and highways. Therefore, based on research, more accurate methods for assessing the capacity of road infrastructure are being developed. This paper presents the results of the research of weaving segments. It is focused on capacity assessment of these sections within the Czech Republic. Attention is focused especially on weaving segments in urban conditions with high traffic volume and on road sections with a speed limit less than 80 km per hour. Research verified the possibility of using these purposes by existing methodology developed for roads with a speed limit up to 80 km per hour.

Document type: Article

An EMD–SARIMA-Based Modeling Approach for Air Traffic Forecasting

Scipedia content — Tue, 23 Mar 2021 02:17:08 +0100

The ever-increasing air traffic demand in China has brought huge pressure on the planning and management of, and investment in, air terminals as well as airline companies. In this context, accurate and adequate short-term air traffic forecasting is essential for the operations of those entities. In consideration of such a problem, a hybrid air traffic forecasting model based on empirical mode decomposition (EMD) and seasonal auto regressive integrated moving average (SARIMA) has been proposed in this paper. The model proposed decomposes the original time series into components at first, and models each component with the SARIMA forecasting model, then integrates all the models together to form the final combined forecast result. By using the monthly air cargo and passenger flow data from the years 2006 to 2014 available at the official website of the Civil Aviation Administration of China (CAAC), the effectiveness in forecasting of the model proposed has been demonstrated, and by a horizontal performance comparison between several other widely used forecasting models, the advantage of the proposed model has also been proved.

Document type: Article

Consensus-Based Cooperative Control Based on Pollution Sensing and Traffic Information for Urban Traffic Networks

Scipedia content — Tue, 23 Mar 2021 02:05:10 +0100

Nowadays many studies are being conducted to develop solutions for improving the performance of urban traffic networks. One of the main challenges is the necessary cooperation among different entities such as vehicles or infrastructure systems and how to exploit the information available through networks of sensors deployed as infrastructures for smart cities. In this work an algorithm for cooperative control of urban subsystems is proposed to provide a solution for mobility problems in cities. The interconnected traffic lights controller ("i"TLC"/i") network adapts traffic lights cycles, based on traffic and air pollution sensory information, in order to improve the performance of urban traffic networks. The presence of air pollution in cities is not only caused by road traffic but there are other pollution sources that contribute to increase or decrease the pollution level. Due to the distributed and heterogeneous nature of the different components involved, a system of systems engineering approach is applied to design a consensus-based control algorithm. The designed control strategy contains a consensus-based component that uses the information shared in the network for reaching a consensus in the state of "i"TLC"/i" network components. Discrete event systems specification is applied for modelling and simulation. The proposed solution is assessed by simulation studies with very promising results to deal with simultaneous responses to both pollution levels and traffic flows in urban traffic networks.

Authors wish to thank the support given by the project IoSENSE: Flexible FE/BE Sensor Pilot Line for the Internet of Everything, funded by the Electronic Component Systems for European Leadership Joint (ECSEL) Undertaking under grant agreement No 692480.This work has been also supported by MINECO (Spain) through the project RTC-2015-3942-4 TCAP: Auto. Moreover, Raúl M. del Toro acknowledges the financial support received from MINECO through grant “Juan de la Cierva-incorporación”, code IJCI-2014-20169.

We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

Document type: Article

Traffic congestion analysis using travel time ratio and degree of saturation on road sections in Palembang, Bandung, Yogyakarta, and Surakarta

Scipedia content — Tue, 23 Mar 2021 02:02:59 +0100

Traffic performance have been measured based on degree of saturation, velocity, travel time, and delays. However, they weren’t enough to measure the traffic fluctuation that happen on normal days. This study aims to develop some modified analysis about traffic congestion based on the degree of saturation (DS) and travel time ratio (TTR). The travel time ratio is defined as a ratio between the travel time at peak hour and the travel time at off-peak hour in a certain road section. Traffic congestion conditions are classified into 4 categories: Peak-hour Congestion, Lengthy Congestion, Momentary Congestion, and Smooth Traffic. Based on survey results on road sections in Palembang, Bandung, Yogyakarta, and Surakarta, it can be concluded that peak-hour congestion occurs when TTR > 1,40 and DS > 0,75, lengthy congestion occurs when TTR 0,75, momentary congestion occurs when TTR > 1,40 and DS

Towards Sustainable Urban Transportation in Ghana: Exploring Adults’ Intention to Adopt Cycling to Work Using Theory of Planned Behaviour and Structural Equation Modelling

Scipedia content — Tue, 23 Mar 2021 01:51:42 +0100

Cycling is considered an environmentally-friendly mode of transport that offers many personal benefits including health, affordability and flexibility of travel. To encourage more people to cycle, especially in contexts where cycle ownership and ridership is considerably low, requires understanding the underlying motivations and barriers to cycling. This study models the behavioural influences of individuals’ (N = 348) intended adoption of cycling to work in the Kumasi metropolis in Ghana, West Africa. It deploys the theory of planned behaviour (TPB) to explore the extent to which socio-psychological constructs namely; Attitude, perceived behavioural (PBC) and subjective norm (SN) influence intended adoption of cycling as work travel mode. The influence of participants’ perception of their physical environment as well as their personal characteristics, cycling history and bicycle ownership are also examined. Results of an SEM analysis showed that among the TPB constructs, PBC (i.e. perception of self-confidence, personal control and ease of cycling) had the strongest positive and direct effect on participants’ intention to cycle to work. Negative associations were found between attitude and SN and SN and PBC, suggesting that belief about the prestige of cycling relative to other modes, and approval of society and significant others of cycling, influenced perception of control and confidence as well as attitude with respect to cycling. Also, participants’ perception of their environment including traffic-lights, traffic volume and congestion, as well as bicycle ownership and frequency of use, increased intended adoption of cycling. Finally, being female decreased the likelihood of intended cycling adoption. Cycling promotion interventions could be anchored on people’s already strong perceived control and confidence to cycle while addressing negative perceptions and attitudes towards cycling as a mainstream transport mode.

Document type: Article

ON A FAIR MANIFOLD FARE RATING ON A LONG TRAFFIC LINE

Scipedia content — Tue, 23 Mar 2021 01:45:30 +0100

The paper studies the possibilities to design a fair manifold tariff on a long traffic line. If a single tariff is used on a long bus or railway line, passengers travelling long distances are favoured at the expense of those travelling short distances. The fairest approach to tariff is setting an individual tariff for every origin–destination relation of line stops that expresses real travel costs. However, sometimes the individual tariff is too complicated and is therefore replaced by double-, triple- or manifold tariff. This paper shows how to design a manifold tariff in order to minimize unfairness to passengers.

Document type: Article

Geospatial Analysis of Earthquake Damage Probability of Water Pipelines Due to Multi-Hazard Failure

Scipedia content — Tue, 23 Mar 2021 01:05:28 +0100

The main purpose of this study is to develop a Geospatial Information System (GIS) model with the ability to assess the seismic damage to pipelines for two well-known hazards, including ground shaking and ground failure simultaneously. The model that is developed and used in this study includes four main parts of database implementation, seismic hazard analysis, vulnerability assessment and seismic damage assessment to determine the pipeline’s damage probability. This model was implemented for main water distribution pipelines of Iran and tested for two different earthquake scenarios. The final damage probability of pipelines was estimated to be about 74% for water distribution pipelines of Mashhad including 40% and 34% for leak and break, respectively. In the next step, the impact of each earthquake input parameter on this model was extracted, and each of the three parameters had a huge impact on changing the results of pipelines’ damage probability. Finally, the dependency of the model in liquefaction susceptibility, landslide susceptibility, vulnerability functions and segment length was checked out and specified that the model is sensitive just to liquefaction susceptibility and vulnerability functions.

Document type: Article

Smart Cities: Transport Challenges of the Macedonian Capital City

Scipedia content — Tue, 23 Mar 2021 00:59:20 +0100

"jats:p"Smart City as a concept presupposes using new information and communication technologies in order to improve the quality of life within a particular geographic area. There are six different pillars in the frame of this concept and their one purpose is to achieve better efficiency of city operations. Smart mobility and transport are some of them. The efforts of traditional cities to become smart are not easily and quickly achievable. Numerous traffic solutions have already been implemented in different cities all over the world that make the ‘jump’ from traditional city to smart city. This paper provides an overview of the ‘smart’ transport solutions that have been implemented in the city of Skopje as a traditional city, which is on its way to becoming a smart city."/jats:p" "jats:p"The presented smart solutions are related to traffic management and control area and are aimed at alleviating traffic problems. The focus is on non-motorized solutions, e-vehicles, adaptive traffic control systems and public transport solutions. Several aims have been set in this paper – to promote the achievements of the municipality of Skopje aimed at transforming Skopje into a smart city in a transport area; to present its functionality, and to point out the disadvantages related to law regulations and the interconnection of all stakeholders involved. Finally, the idea is to provide a starting point for future research and to recommend future steps in this direction in the city of Skopje.

Document type: Article

Damage to plastic pipelines and its consequences

Scipedia content — Tue, 23 Mar 2021 00:18:52 +0100

The paper will present the issue of damage to plastic pipelines - especially thermoplastic ones, while also considering the aspect of testing their technical condition using standard diagnostic tools. The results of the strength analysis for the effects of local overheating of the sewage pipe wall - as an effect of inflow of sewage with a high temperature, will also be presented.

Document type: Article

Cost of Capital Estimation for Highway Concessionaires in Chile

Scipedia content — Mon, 22 Mar 2021 23:58:54 +0100

In this paper, we present the cost of capital estimation for highway concessionaires in Chile. We estimated the cost of equity and the cost of debt and determined the capital structure for each one of twenty-four concessionaires that operate highways. We based our estimations on the developments of Sharpe (1964), Modigliani and Miller (1958), and Maquieira (2009), which were also compared with the Brusov et al. (2015) developments. We collected stock prices for different highway concessionaires around the world from Google Finance and Reuters’ websites in order to determine the Beta of equity using a representative company. After that, we estimated the cost of equity considering Hamada (1969) and a Capital Asset Pricing Model. Then, we estimated the cost of capital using the cost of debt and the capital structure of Chile’s highway concessionaires. With all above, we were able to determine the Weighted Average Cost of Capital (WACC) for highway concessions which ranges from 5.49 to 6.62%.

Document type: Article

European cyclists' travel behavior: Differences and similarities between seven European (PASTA) cities

Scipedia content — Mon, 22 Mar 2021 23:48:32 +0100

Background The number of trips of the average urban inhabitant per year has grown steadily in recent years – but we are actually moving (our bodies) less. Every day, millions of trips are made by car (where 50% of these are less than 5 km) or other motorised private vehicles as well as with public transport, while only a small percentage of trips are made by active modes, such as cycling and walking. This lack of physical activity causes major health problems for individuals and great economic costs for society as a whole. To reverse these negative impacts the World Health Organisation (WHO) recommends a minimum of 150 minutes of moderate physical activity per week (e.g. 30 minutes 5 times per week). Replacing short motorized trips can feasibly increase physical activity in everyday life. Methods PASTA “Physical Activity trough sustainable transport approaches” collected data in a longitudinal web-based survey with a cohort design to study the effects of active mobility on overall physical activity and health. The target population for the survey was the entire adult population in 7 European Cities. In total, more than 12.000 people participated in the survey with half of them filling in valid travel diaries on actual trips on a regular basis. Results Differences in sociodemographics and travel behaviour of cyclists in the seven cities will be shown in the paper. Preliminary results reveal that more than 2.000 participants from the total sample can be identified as regular cyclists (reported in their trip diaries) with an average age of 40 years. Most of them are highly educated and full time employed. In comparison to non-regular cyclists, the share of female is lower; however the share of people who have a driving licence and who have at least sometimes access to a car is higher within the group of cyclists. About 85% of regular cyclists reach at least 30 cycling-minutes per reported day. This indicates that a high share of regular cyclists can reach the WHO´s recommended level only by routine cycling trips. Further the threshold of reaching the minimum recommendation by cycling will be analysed between the cities. Conclusions In this study, we compare cyclists and their travel behaviour in seven European cities. Our first results indicate, that cycling as a mean of transport can help reach the WHO’s physical activity recommendations and including physical activity into daily life without much of extra effort.

Document type: Article

KASTOR – A VEHICLE AND CREW SCHEDULING SYSTEM FOR REGULAR BUS PASSENGER TRANSPORT

Scipedia content — Mon, 22 Mar 2021 23:44:10 +0100

Summary. The challenge in vehicle and crew scheduling is to arrange a given set of bus trips into running boards while minimizing certain objectives and complying with a given set of constraints. This scheduling was solved several tens years ago manually by a dispatcher who used his skill, experience, knowledge of history, and intuition. This attitude worked quite well in small instances but could not be applied in larger ones. Development of computers brought opportunities to build computerized vehicle and crew optimization systems. This paper describes a computer system KASTOR developed for vehicle and crew optimization, which complies with the special requirements of Czech and Slovak bus providers, and is significantly different from those in some west European countries.

Document type: Article

Perencanaan Integrasi Transportasi Antarmoda Dalam Pembangunan Bandar Udara (Studi Kasus: Pembangunan Bandar Udara di Kertajati)

Scipedia content — Mon, 22 Mar 2021 23:34:13 +0100

Bandar udara merupakan infrastruktur vital di suatu wilayah. Bandar udara akan meningkatkan pertumbuhan ekonomi, selain mendukung konektivitas antar wilayah. Perencanaan integrasi transportasi antarmoda menjadi hal yang perlu diperhatikan oleh perencana bandar udara sejak awal pembangunan bandar udara untuk mempercepat pengoperasian bandar udara serta menghindari adanya permasalahan di kemudian hari. Tujuan dari studi ini adalah untuk menginterpretasikan konsep perencanaan integrasi transportasi antarmoda yang dapat diimplementasikan di Indonesia khususnya infrastruktur bandar udara berdasarkan dari pengalaman negara lain. Studi ini menggunakan metode kualitatif yaitu tinjauan pustaka dan analisis perbandingan. Hasil dari studi ini adalah Indonesia dapat belajar dari kesuksesan negara lain seperti Jerman dalam perencanaan integrasi transportasi antarmoda di bandar udara berdasarkan beberapa aspek integrasi seperti organisasi, operasional, fisik, dan motif. Mewujudkan sistem transportasi yang berkesinambungan dari dan ke bandar udara akan menarik permintaan masyarakat yang lebih tinggi untuk menggunakan bandar udara di Kertajati.
[Intermodal Transportation Integration Planning in Airport Development (Case Study: Airport Development in Kertajati)] An airport is the vital infrastructure in a region. Airport will increase the economic growth, besides supporting inter-regional connectivity. Intermodal transportation integration planning should be considered by airport planner since the beginning of airport development time in order to fasten airport operation and to avoid problems in the future. The purpose of this study is to interpret intermodal transportation integration planning concept that can be implemented in Indonesia spesifically for airport infrastructure regarding to the experiences from other country. This study uses qualitative method through literature review and comparative analysis. The result of this study is that Indonesia can learn from the successful of other country like Germany in intermodal transportation integration planning in airport based on some integration aspects like organizational, operational, physical, and motives. Realizing seamless transportation system from and to the aiport will attract the higher people demand for using airport in Kertajati.

Document type: Article

Analysis of the impact of pump system control on pressure gradients during emergency leaks in pipelines

Scipedia content — Mon, 22 Mar 2021 23:29:52 +0100

The impact of a pump control system on the recorded pressure values along the pipeline during emergency leaks is discussed in the paper. A comparison was made for the designed experimental installation with a length of 1100 m and a diameter of DN 63 mm. The calculations were made using the Epanet 2 program. Results of the performed calculations prove that apart from a detailed description of hydraulic parameters of the pipeline on the size of emergency leaks from the pipeline, it is also important to properly describe the pump control system.

Document type: Article

ENVIRONMENTAL ASSESSMENT OF ROAD TRANSPORT IN A PASSENGER CAR USING THE LIFE CYCLE APPROACH

Scipedia content — Mon, 22 Mar 2021 23:27:05 +0100

Environmental issues are an increasingly important aspect of management in the transport sector; new methods have been developed for assessment of the environment in the transport sector using the life cycle approach. The paper presents the application of Well to Wheel (WTW) and Life Cycle Assessment (LCA) in the transport sector. The WTW method focuses on energy analysis and greenhouse gas emissions during the life cycle of fuels. WTW is used to support decision-making on the environmental aspects of transport, particularly with regard to fuel life cycle management, but this method omits important stages in the life cycle, particularly the ones regarding important circular economy guidelines such as reduction of natural resource consumption, impact on human health, etc. The LCA method provides a much broader approach to environmental assessment than WTW. LCA takes into consideration environmental impact in the whole life cycle of the vehicle, from the stage of production, through the period of exploitation, and finally its disposal.

Document type: Article

Calculation Method for Load Capacity of Urban Rail Transit Station considering Cascading Failure

Scipedia content — Mon, 22 Mar 2021 23:01:04 +0100

The load capacity of urban rail transit station is of great significance to provide reference in station design and operation management. However, it is difficult to carry out quantitative calculation quickly and accurately due to the complex interaction among passenger behaviors, facility layout, and the limit capacity of single facility. In this paper, the association network of facilities is set up based on the analysis of passenger service chain in station. Then the concept of cascading failure is introduced to the dynamic calculation model of load capacity, which is established on the user-equilibrium allocation model. The solution algorithm is optimized with node attack strategy of complex network to effectively reduce the computational complexity. Finally, a case study of Lujiabang Road Station in Shanghai is carried out and compared with the simulation results of StaPass, verifying the feasibility of this approach. The proposed method can not only search for the bottleneck of capacity, but also help to trace the loading variation of facilities network in different scenarios, providing theoretical supports on passenger flow organization.

Document type: Article

Defining Reserve Times for Metro Systems: An Analytical Approach

Scipedia content — Mon, 22 Mar 2021 22:59:37 +0100

The aim of this paper is to provide an analytical approach for determining operational parameters for metro systems so as to support the planning and implementation of energy-saving strategies. Indeed, one of the main targets of train operating companies is to identify and implement suitable strategies for reducing energy consumption. For this purpose, researchers and practitioners have developed energy-efficient driving profiles with the aim of optimising train motion. However, as such profiles generally entail an increase in travel times, the operating parameters in the planned timetable need to be appropriately recalibrated. Against this background, this paper develops a suitable methodology for estimating reserve times which represent the main rate of extra time needed to put ecodriving strategies in place. Our proposal is to exploit layover times (i.e., times spent by a train at the terminus waiting for the next trip) for energy-saving purposes, keeping buffer times intact in order to preserve the flexibility and robustness of the timetable in case of delays. In order to show its feasibility, the approach was applied in the case of a real metro context, whose service frequency was duly taken into account. In particular, after stochastic analysis of the parameters involved for calibrating suitable buffer times, different operating schemes were simulated by analysing the relationship between layover times, number of convoys, and feasible headway values. Finally, some operation configurations are analysed in order to quantify the amount of energy that can be saved.

Document type: Article

Collective thinking approach for improving leak detection systems

Scipedia content — Mon, 22 Mar 2021 22:37:04 +0100

Water mains, especially old pipelines, are consistently threatened by the formation of leaks. Leaks inherit increased direct and indirect costs and impacts on various levels such as the economic field and the environmental level. Recently, financially capable municipalities are testing acoustic early detection systems that utilize wireless noise loggers. Noise loggers would be distributed throughout the water network to detect any anomalies in the network. Loggers provide early detection via recording and analyzing acoustic signals within the network. The city of Montreal adopted one of the leak detection projects in this domain and had reported that the main issue that hinders the installed system is false alarms. False alarms consume municipality resources and funds inefficiently. Therefore, this paper aims to present a novel approach to utilize more than one data analysis and classification technique to ameliorate the leak identification process. In this research, acoustic leak signals were analyzed using Fourier Transform, and the multiple frequency bandwidths were determined. Three models were developed to identify the state of the leak using Naïve Bayes (NB), Deep Learning (DL), and Decision Tree (DT) Algorithms. Each of the developed models has an accuracy ranging between 84% to 89%. An aggregator approach was developed to cultivate the collective approaches developed into one single answer. Through aggregation, the accuracy of leak detection improved from 89% at its best to 100%. The design, implementation approach and results are displayed in this paper. Using this method helps municipalities minimize and alleviate the costs of uncertain leak verifications and efficiently allocate their resources.

Document type: Article

Cooperative vehicles for robust traffic congestion reduction: An analysis based on algorithmic, environmental and agent behavioral factors

Scipedia content — Mon, 22 Mar 2021 22:35:49 +0100

Traffic congestion continues to be a persistent problem throughout the world. As vehicle-to-vehicle communication develops, there is an opportunity of using cooperation among close proximity vehicles to tackle the congestion problem. The intuition is that if vehicles could cooperate opportunistically when they come close enough to each other, they could, in effect, spread themselves out among alternative routes so that vehicles do not all jam up on the same roads. Our previous work proposed a decentralized multiagent based vehicular congestion management algorithm entitled Congestion Avoidance and Route Allocation using Virtual Agent Negotiation (CARAVAN), wherein the vehicles acting as intelligent agents perform cooperative route allocation using inter-vehicular communication. This paper focuses on evaluating the practical applicability of this approach by testing its robustness and performance (in terms of travel time reduction), across variations in: (a) environmental parameters such as road network topology and configuration; (b) algorithmic parameters such as vehicle agent preferences and route cost/preference multipliers; and (c) agent-related parameters such as equipped/non-equipped vehicles and compliant/non-compliant agents. Overall, the results demonstrate the adaptability and robustness of the decentralized cooperative vehicles approach to providing global travel time reduction using simple local coordination strategies.

Document type: Article

Low-carbon transport policy in four ASEAN countries: Developments in Indonesia, the Philippines, Thailand and Vietnam

Scipedia content — Mon, 22 Mar 2021 22:31:12 +0100

Emerging countries in Southeast Asia are facing considerable challenges in addressing rising motorisation and its negative impact on air quality, traffic, energy security, liveability, and greenhouse gas emissions. This paper presents a comparative analysis of the approach and status of sustainable, low-carbon transport policy in ASEAN countries and identifies differences and similarities. The methodology is based on a taxonomy of policy components as developed by Howlett and Cashore. The data come from comprehensive country studies for Indonesia, the Philippines, Thailand and Vietnam and interviews with policymakers. We find that each country has a specific set of goals, objectives and targets that support sustainable transport, and, directly or indirectly, climate change mitigation. In terms of specific mechanisms and calibrations, which we analyse based on the Avoid−Shift−Improve approach, there are notable differences between the countries, for example in terms of fuel economy policy. Even though an initial response to climate change mitigation challenges is visible in these countries’ transport policies, much more effort is required to enable a transition to a transport system compatible with long-term climate change and sustainable development targets.

Document type: Article

Detecting Different Road Infrastructural Elements Based on the Stochastic Characterization of Speed Patterns

Scipedia content — Mon, 22 Mar 2021 22:05:05 +0100

The automatic detection of road related information using data from sensors while driving has many potential applications such as traffic congestion detection or automatic routable map generation. This paper focuses on the automatic detection of road elements based on GPS data from on-vehicle systems. A new algorithm is developed that uses the total variation distance instead of the statistical moments to improve the classification accuracy. The algorithm is validated for detecting traffic lights, roundabouts, and street-crossings in a real scenario and the obtained accuracy (0.75) improves the best results using previous approaches based on statistical moments based features (0.71). Each road element to be detected is characterized as a vector of speeds measured when a driver goes through it. We first eliminate the speed samples in congested traffic conditions which are not comparable with clear traffic conditions and would contaminate the dataset. Then, we calculate the probability mass function for the speed (in 1 m/s intervals) at each point. The total variation distance is then used to find the similarity among different points of interest (which can contain a similar road element or a different one). Finally, a k-NN approach is used for assigning a class to each unlabelled element. The research leading to these results has received funding from the “HERMES-Smart Driver” Project TIN2013-46801-C4-2-R (MINECO), funded by the Spanish Agencia Estatal de Investigación (AEI), and the “Analytics Using Sensor Data for Flatcity” Project TIN2016-77158-C4-1-R (MINECO/ERDF, EU) funded by the SpanishAgencia Estatal de Investigación (AEI) and the European Regional Development Fund (ERDF).

Document type: Article

A Witricity-Based High-Power Device for Wireless Charging of Electric Vehicles

Scipedia content — Mon, 22 Mar 2021 22:03:51 +0100

In this paper, a Witricity-based high-power device is proposed for wireless charging of electric vehicles. According to the specific requirements of three-stage charging for electric vehicles, four compensation modes of the Witricity system are analyzed by the Loosely Coupled Theory among transformer coils and the Substitution Theorem in circuit theory. In addition, when combining voltage withstand levels, the current withstand capability, the switching frequency of electronic switching tubes, and the features of the resonant circuit, the series-parallel (SP) compensation mode is selected as the best compensation mode for matching the capacitor of the system. The performances of coils with different ferrite core arrangements are compared by simulations and models. The feasibility of the system is verified theoretically and the system functions are evaluated by the joint simulation of Simplorer and Maxwell. Finally, a Witricity-based high-power device is proposed as designed, and the correctness of theoretical analyses and simulation results are verified.

Document type: Article

An Improved Single-Lane Cellular Automaton Model considering Driver’s Radical Feature

Scipedia content — Mon, 22 Mar 2021 21:56:33 +0100

Traffic flow models are of vital significance to study the traffic system and reproduce typical traffic phenomena. In the process of establishing traffic flow models, human factors need to be considered particularly to enhance the performance of the models. Accordingly, a series of car-following models and cellular automaton models were proposed based on comprehensive consideration of various driving behaviors. Based on the comfortable driving (CD) model, this paper innovatively proposed an improved cellular automaton model incorporating impaired driver’s radical feature (RF). The impaired driver’s radical feature was added to the model with respect to three aspects, that is, desired speed, car-following behavior, and braking behavior. Empirical data obtained from a highway segment was used to initialize impaired driver’s radical feature distribution and calibrate the proposed model. Then, numerical simulations validated that the proposed improved model can well reproduce the traffic phenomena, as shown by the fundamental diagram and space-time diagram. Also, in low-density state, it can be found that the RF model is superior to the CD model in simulating the speed difference characteristics, where the average speed difference of adjacent vehicles for RF model is more consistent with reality. The result also discussed the potential impact of impaired drivers on rear-end collisions. It should be noted that this study is an early stage work to evaluate the existence of impaired driving behavior.

Document type: Article

Mathematical model and regulation of the two interconnected vessels

Scipedia content — Mon, 22 Mar 2021 21:50:47 +0100

This article is about practical approach to the problem of cascade level-flow control and temperature regulation. PI-controller designing practices for level-flow cascade control system are explained in this article. Heat exchange model between reservoirs, optimal control of temperature in the reservoir and finding of heater switch-over time are considered as well. Main purpose of such model is to explain temperature regulation method simultaneously with level regulation in the reservoir. Article in English. Dviejų tarpusavyje sujungtų rezervuarų matematinis modelis ir valdymas Santrauka Straipsnyje sprendžiama kaskadinio tėkmės lygio valdymo ir temperatūros reguliavimo tarp dviejų sujungtų rezervuarų problema. Pateikiami PI valdiklio kūrimo metodas skysčio tėkmės lygiui valdyti, šilumos mainų tarp dviejų rezervuarų modelis, temperatūros valdymo šildytuvo veikimo laiko paieškos algoritmai. Pagrindinė darbo idėja – paaiškinti, kaip reguliuoti temperatūrą, tuo pačiu metu reguliuojant skysčio tėkmės lygį. Reikšminiai žodžiai: kaskadinio valdymo sistema, tėkmės lygio ir temperatūros reguliavimas, optimalus valdymas, vamzdynai.

Document type: Article

Analysis of CO2 transmission pipelines for CO2 enhanced oil recovery networks: gas field X to oil field Y

Scipedia content — Mon, 22 Mar 2021 21:46:12 +0100

The aim of this study is to analyze the CO"jats:sub"2"/jats:sub" transmission pipeline from gas field X to oil field Y by comparing alternative routes, CO"jats:sub"2"/jats:sub" phases, design parameters, equipment used and economic aspects, with the objective of identifying the most efficient transmission system. The 100 MSCFD of CO"jats:sub"2"/jats:sub" that is normally removed from gas field X will be used and transmitted to oil field Y for enhanced oil recovery (EOR). CO"jats:sub"2"/jats:sub" can be transported in three phases - gas, fluid or dense vapour. Because of the corrosive properties of CO"jats:sub"2"/jats:sub" when in contact with water, materials with high corrosion resistance, such stainless steel or reinforced carbon, should be used. Stainless steel is commonly used for the transport of corrosive fluids such as CO"jats:sub"2"/jats:sub" but is expensive, while the least expensive material commonly used is reinforced fibre; however, this material has low strength at high pressure. On the other hand, while carbon steel is known for its high strength and durability it has poor resistance to corrosion. Therefore, the selection of materials for pipeline construction and the design parameters applied will be studied here to determine the best option for CO"jats:sub"2"/jats:sub" transmission. For comparison, two alternative routes, one with existing rights of way (the ROW route) and one all-new route, will be compared with each other. Then, CO"jats:sub"2"/jats:sub" phase transmission will be compared for liquid, gas and dense vapour phases, together with the design parameters applied and required equipment. Pipe diameter will be calculated along with pipe wall thickness and other requirements of parameter design for transmission of CO"jats:sub"2"/jats:sub". Economic analysis will then be performed for each scenario to ascertain the minimum cost while still meeting necessary technical requirements. Capital expenditure (CAPEX), operating expenditure (OPEX) and other variables will be investigated and analyzed using sensitivity testing to determine the influence of each component variation on each CO"jats:sub"2"/jats:sub" transmission pipeline. From the analysis applied to each scenario the optimal pipeline transmission scenarios in terms of design and cost to meet the CO"jats:sub"2"/jats:sub" enhanced oil-recoverynetwork needs for gas field X to oil field Y will be obtained.

Document type: Article

Investigation of the factors affecting the consistency of short-period traffic counts

Scipedia content — Mon, 22 Mar 2021 21:20:40 +0100

The main intent of this study is to investigate the accuracy of short-duration traffic counts conducted during winter months. The investigation is based on 11-year sample data collected using permanent traffic counters at various locations in Alberta, Canada. Four types of road sites: commuter, regional commuter, rural long-distance, and recreational sites are studied. The sample data constitute six different durations of counts (12-, 24-, 48-, 72-, 96-h, and 1 week) taken during summer and winter months. The coefficient of variation (CV) is used as the relative measure of deviation for counts of different durations to measure the accuracy of short-period traffic counts. The study results indicate that 48-h count seems to be the most cost-effective counting interval during both summer and winter months. It is also found that the lowest values of CV result for counts taken at commuter sites, and the highest values are observed for recreational sites. Frequent changes in temperature and other weather events cause significant variation in traffic volume, which results in an increase in CV values for counts taken during winter months. The application of an adjustment factor to remove the effect of cold and snow from short-period counts is also included in this study. Introduced adjustment factors can reduce the values of CV for all counts taken during winter months. The findings of this study can lead highway agencies to improve the cost-effectiveness of their short-period traffic counting programs.

Document type: Article

Plan for sustainable urban logistics – comparing between Scandinavian and UK practices

Scipedia content — Mon, 22 Mar 2021 21:10:04 +0100

Introduction Common practices in current urban logistics planning in Scandinavia and the UK, and the degree to which SUTP (Sustainable Urban Transport Plan), SUMP (Sustainable Urban Mobility Plans) and SULP (Sustainable Urban Logistics Plans) guidelines are used, are examined in this paper. Methods A systematic literature review identifies relevant studies based on predefined inclusion criteria: mobility, freight, urban, plan. Results It is found that urban freight plans are used more frequently in the UK than in the Scandinavian countries. SULPs (freight strategies, action plans or parts of a mobility plan) follow a structure that identifies the current situation and defines the strategic context, vision, targets and objectives using selected policy measures, measures that are dependent on geographical scope. Conclusions Urban freight plans are designed with a sustainability perspective to define visions and policy measures for urban freight. SUTP, SUMP and SULP methodologies are used in existing Scandinavian and UK urban freight plans, especially when a collaborative planning approach is being practiced. The emphasis on urban freight is challenged by the regional perspective. Integrating urban freight in general planning procedures or transport planning is important. Government guidance and sustainable strategies can provide a planning methodology and, therefore, based on national guidelines further European structural standardisation could be beneficial. Identification of freight plans is crucial if the contributions they make are to be determined.

Document type: Article

Evaluation of peak water demand factors in puglia (Southern Italy)

Scipedia content — Mon, 22 Mar 2021 21:07:04 +0100

In the design of a water supply network, the use of traditional formulas of the peak factor may lead to over-dimensioning the network pipelines, especially in small towns. This discrepancy is probably due to changes in human habits as a consequence of a general improvement of living conditions. Starting from these considerations, and given the availability of a wide random sample data, an analysis of the water demand for several towns in Puglia was carried out, leading to the definition of a relationship between the above mentioned peak factor and the number of inhabitants, based on a stochastic approach. An interesting outcome of this study is that the design of water supply network is possible without considering the use of monthly and weekly peak factors, since the current water demands appear not specifically sensitive to these variations; moreover, the magnitude of the peak factor, as shown by measured data, is considerably lower compared to literature values, especially for small towns.

Document type: Article

Partial Stray Inductance Modeling and Measuring of Asymmetrical Parallel Branches on the Bus-Bar of Electric Vehicles

Scipedia content — Mon, 22 Mar 2021 21:06:05 +0100

In order to increase the power rating of electric vehicles, insulated gate bipolar translator (IGBT) modules with multiple power terminals are usually adopted. The transient current sharing of the same polarity power terminals is related to the stray inductance in the branches of the bus-bar. Based on the laminated bus-bar of a three-phase inverter in the electric vehicles that consists of asymmetrical parallel branches, this paper investigates the transient current imbalance sharing caused by the asymmetrical stray inductance in the parallel branches of the bus-bar from the view of energy storing and releasing of stray inductance for the first time. Besides, the partial self-inductance and mutual-inductance model of the parallel branches is set up. Finally, a high-precision partial stray inductance measurement method is proposed, and the accuracy of the partial stray inductance model for asymmetrical parallel branches is verified by experimental tests.

Document type: Article

Open data in power grid modelling: New approaches towards transparent grid models

Scipedia content — Mon, 22 Mar 2021 21:02:46 +0100

In order to analyse the mid- and long-term impacts of energy related policies, different modelling approaches can be derived. However, the results of even the best energy system model will highly depend on the underlying input data. First, in this contribution the importance and availability issues of grid data in the context of energy system modelling are highlighted. Second, this paper focuses on power grid modelling based on open and publicly available data from OpenStreetMap using open source software tools. Two recent approaches developed to build electrical transmission network models using openly available data sources are presented and discussed. The proposed methods provide transparent assumptions, simplifications and documentation of grid modelling. This results in the ability of scientists and other stakeholders to validate, discuss or reproduce the results of energy system models. Thus the new open approaches offer a unique opportunity to increase transparency, comparability and reproducibility of results in energy system modelling.

Document type: Article

SOLVING TRANSPORT LOGISTICS PROBLEMS IN A VIRTUAL ENTERPRISE THROUGH ARTIFICIAL INTELLIGENCE METHODS

Scipedia content — Mon, 22 Mar 2021 20:54:29 +0100

The paper offers a solution to the problem of material flow allocation within a virtual enterprise by using artificial intelligence methods. The research is based on the use of fuzzy relations when planning for optimal transportation modes to deliver components for manufactured products. The Fuzzy Logic Toolbox is used to determine the optimal route for transportation of components for manufactured products. The methods offered have been exemplified in the present research. The authors have built a simulation model for component transportation and delivery for manufactured products using the Simulink graphical environment for building models.

Document type: Article

Task-Oriented and Relationship-Building Communications between Air Traffic Controllers and Pilots

Scipedia content — Mon, 22 Mar 2021 20:44:45 +0100

By questioning the lopsided attention on task-oriented factors in air traffic controller-pilot communication, the current study places an equal weighting on both task-oriented and relationship-building communications, and investigates how each type of communication influences sustainable performance in airline operation team. Results show that both task-oriented and relationship-building communications in terms of sustainability of team process predicted greater communication satisfaction at work. Also, both task interdependence and shared leadership influenced both types of air traffic controller-pilot communication. However, only relationship-building communication had a direct influence on perceived work performance whereas task-oriented communication had not. Along with task-oriented factors, this study raises the relationship-oriented factors as important resources for the sustainable team performance in airline industry.

Document type: Article

The BICS — Advanced Method of the Electronic Ship Reporting for the RIS Centre

Scipedia content — Mon, 22 Mar 2021 20:36:18 +0100

"jats:p"The article presents principles of transmission and processing of the data in electronic reporting of river ships used in inland navigation. The new standard of electronic reporting of ships was shown — system Barge Information and Communication System (BICS). Results and analysis of surveys of real duplex transmission of data in BICS system for purpose of RIS Centre were presented.

Document type: Article

Evaluation of Driver Compliance to Displayed Variable Advisory Speed Limit Systems: Comparison between Germany and the U.S.

Scipedia content — Mon, 22 Mar 2021 20:35:32 +0100

Variable Speed Limit (VSL) and Variable Advisory Speed (VAS) systems are applications of a growing field of active traffic management systems (ATM). This technology aims to improve safety while reducing congestion and emissions. VSL is common on German freeways, harmonizing traffic flow during congestion and weather events. Portland, Oregon installed a VAS system (advisory meaning it is not automatically enforced) on an eleven km (7 mile) segment of heavily congested urban freeway. The Portland region maintains archived, high-resolution data of both VAS sign messages and speed detection loop feedback, permitting reconstruction of traffic and sign data. This work analyses over 30 days of archived data from the Portland site in order to study driver compliance to the VAS signs. The focus is to suggest methods and parameters to score system performance. Such an analysis could benefit new rollouts of VAS corridors by providing system performance feedback and shed light on options for improving system performance.

Document type: Article

Research on Taxi Driver Strategy Game Evolution with Carpooling Detour

Scipedia content — Mon, 22 Mar 2021 20:33:56 +0100

For the problem of taxi carpooling detour, this paper studies driver strategy choice with carpooling detour. The model of taxi driver strategy evolution with carpooling detour is built based on prospect theory and evolution game theory. Driver stable strategies are analyzed under the conditions of complaint mechanism and absence of mechanism, respectively. The results show that passenger’s complaint mechanism can effectively decrease the phenomenon of driver refusing passengers with carpooling detour. When probability of passenger complaint reaches a certain level, the stable strategy of driver is to take carpooling detour passengers. Meanwhile, limiting detour distance and easing traffic congestion can decrease the possibility of refusing passengers. These conclusions have a certain guiding significance to formulating taxi policy.

Document type: Article

On the Dynamic Response Prediction at the Full-Scale Test of Aircraft Component

Scipedia content — Mon, 22 Mar 2021 20:24:55 +0100

"jats:p"Several general effects of boundary conditions and their adequate description at structural dynamic computational simulation constitute the main subject of the discussion. First, an analytical model of elastically supported beam was considered to evaluate the effects of support compliance to the basic dynamic characteristics. Second, a more complex model of a body with elastic support was simulated. Some general properties of structure dynamics were analysed.

Document type: Article

Performance of Commercially Available Supercapacitors

Scipedia content — Mon, 22 Mar 2021 20:24:14 +0100

High energy density storage device exhibiting a reliable lifecycle is needed in the 21st century. Hence, energy storage research is critical for reducing energy consumption. Supercapacitors exhibit such characteristics via interfacial ion electrosorption and fast redox reactions. They are a feasible solution for transportation applications, among others, due to their superb characteristics. In this paper, we provide a background on supercapacitors, review public data on commercially available supercapacitors for performance characteristics, and finally summarize their performance in terms of energy density, equivalent series resistance, and device time consistency.

Document type: Article

Global and Local Path Planning Study in a ROS-Based Research Platform for Autonomous Vehicles

Scipedia content — Mon, 22 Mar 2021 20:17:49 +0100

The aim of this work is to integrate and analyze the performance of a path planning method based on Time Elastic Bands (TEB) in real research platform based on Ackermann model. Moreover, it will be proved that all modules related to the navigation can coexist and work together to achieve the goal point without any collision. The study is done by analyzing the trajectory generated from global and local planners. The software prototyping tool is Robot Operating System (ROS) from Open Source Robotics Foundation and the research platform is the iCab (Intelligent Campus Automobile) from University Carlos III. This work has been validated from a test inside the campus where the iCab has performed the navigation between the starting point and the goal point without any collision. During the experiment, we proved the low sensitivity of the TEB method to variations of the vehicle model configuration and constraints.

Document type: Article

DEFINITION OF PUBLIC SERVICE OBLIGATION POTENTIAL IN THE NEW EU MEMBER STATES

Scipedia content — Mon, 22 Mar 2021 20:17:03 +0100

Summary. This paper deals with public service obligation, a form of state aid that applies to air services. The paper first provides general information on the European legislation applying to this form of state aid, and elaborates the legal framework and general principles. The second part is dedicated to a comparison of a similar subsidizing programme in the USA and Australia. An examination of current imposed public serviceobligation routes in Europe is provided in the following section. The coefficients defining the number of imposed PSO routes per various geo-economic variables have been defined.

Document type: Article

Survey on Ranging Sensors and Cooperative Techniques for Relative Positioning of Vehicles

Scipedia content — Mon, 22 Mar 2021 20:15:25 +0100

Future driver assistance systems will rely on accurate, reliable and continuous knowledge on the position of other road participants, including pedestrians, bicycles and other vehicles. The usual approach to tackle this requirement is to use on-board ranging sensors inside the vehicle. Radar, laser scanners or vision-based systems are able to detect objects in their line-of-sight. In contrast to these non-cooperative ranging sensors, cooperative approaches follow a strategy in which other road participants actively support the estimation of the relative position. The limitations of on-board ranging sensors regarding their detection range and angle of view and the facility of blockage can be approached by using a cooperative approach based on vehicle-to-vehicle communication. The fusion of both, cooperative and non-cooperative strategies, seems to offer the largest benefits regarding accuracy, availability and robustness. This survey offers the reader a comprehensive review on different techniques for vehicle relative positioning. The reader will learn the important performance indicators when it comes to relative positioning of vehicles, the different technologies that are both commercially available and currently under research, their expected performance and their intrinsic limitations. Moreover, the latest research in the area of vision-based systems for vehicle detection, as well as the latest work on GNSS-based vehicle localization and vehicular communication for relative positioning of vehicles, are reviewed. The survey also includes the research work on the fusion of cooperative and non-cooperative approaches to increase the reliability and the availability.

Document type: Article

Real-time distributed economic model predictive control for complete vehicle energy management

Scipedia content — Mon, 22 Mar 2021 20:12:19 +0100

In this paper, a real-time distributed economic model predictive control approach for complete vehicle energy management (CVEM) is presented using a receding control horizon in combination with a dual decomposition. The dual decomposition allows the CVEM optimization problem to be solved by solving several smaller optimization problems. The receding horizon control problem is formulated with variable sample intervals, allowing for large prediction horizons with only a limited number of decision variables and constraints in the optimization problem. Furthermore, a novel on/off control concept for the control of the refrigerated semi-trailer, the air supply system and the climate control system is introduced. Simulation results on a low-fidelity vehicle model show that close to optimal fuel reduction performance can be achieved. The fuel reduction for the on/off controlled subsystems strongly depends on the number of switches allowed. By allowing up to 15-times more switches, a fuel reduction of 1.3% can be achieved. The approach is also validated on a high-fidelity vehicle model, for which the road slope is predicted by an e-horizon sensor, leading to a prediction of the propulsion power and engine speed. The prediction algorithm is demonstrated with measured ADASIS information on a public road around Eindhoven, which shows that accurate prediction of the propulsion power and engine speed is feasible when the vehicle follows the most probable path. A fuel reduction of up to 0.63% is achieved for the high-fidelity vehicle model.

Document type: Article

Review on applications of electric vehicles in the countryside

Scipedia content — Mon, 22 Mar 2021 20:06:39 +0100

BSTRACT: This paper presents the main applications of electric vehicles in rural areas, pointing out the trends and challenges for the future. Technological conditions and difficulties faced by the industry for a wide dissemination of this technology are discussed. The paper described the main researches with proposals to overcome the problems of implementing electric tractors, as supply and electricity storage. Technical and economic comparisons between conventional internal combustion tractors and electric tractors are also presented and discussed. The paper showed the existence of barriers to the implementation of electric vehicles in rural areas, as well as the need for batteries technological evolution, which have high costs and for that reason they are very heavy for these purposes, but there are already systems that can be applied to minimize dependence of fossil fuels in this sector and increase the use of sustainable energy. RESUMO: Este artigo apresenta as principais aplicações de veículos elétricos no meio rural, apontanto as tendências e mudanças futuras. O trabalho discute também as condições tecnológicas e dificuldades enfrentadas pelo setor industrial para a inserção do veículo elétrico no mercado. São apresentados os principais pesquisadores da área com propostas para superar os problemas da implementação dos tratores elétricos, tais como abastecimento e armazenamento de energia elétrica. As comparações técnicas e econômicas entre tratores convencionais, a combustão interna, e tratores elétricos são apresentadas e discutidas. A revisão mostra a existência de barreiras para a implantação dos veículos elétricos no meio rural, como a necessidade de evolução tecnológica das baterias, que apresentam alto custo e ainda são pesadas para este propósito, mas mostra também que já existem sistemas que podem minimizar a dependência de compubstíveis fóceis do setor e aumentar o uso de energia sustentável.

Document type: Article

TIRE WEAR MODELING

Scipedia content — Mon, 22 Mar 2021 19:56:35 +0100

Summary. On the basis of a known relationship, an enhanced model for specific tire wear per kilometer has been developed. It is appropriate for practical use - for evaluation of the influence of different factors. Two types of experiments have been carried out with a testing device - one without sideslip, but with a known longitudinal slip, and the other one with the same longitudinal slip but also with a known sideslip. As a result, the coefficients of the proportion of the developed model have been evaluated. After the model validation, an analytical investigation concerning the influence of tire pressure, sideslip and longitudinal slip on the tire wear has been carried out. The results are presented graphically.

Document type: Article

Indication of the Destruction Stage of Epoxy PES-Filled Composite Using the Connected Parameter of Acoustic Emission Rate and the Spectral Characteristics of AE Signals

Scipedia content — Mon, 22 Mar 2021 19:54:49 +0100

"jats:p"The methods of non-destructive testing have an important role in the problem of maintenance of transport and transport infrastructure. They make possible the early detection of internal defects in engineering structures and elements of vehicle design. The samples of composite materials used in the construction of transport infrastructure elements and transport vehicles have been tested. This paper shows the features of AE, which may allow more efficient and accurate analysis of the state of composite objects. The relation of the intensity and frequency characteristics of signals has been revealed. This work discusses the possibility of unambiguous identification of the stage of composite object destruction on the basis of these parameters.

Document type: Article

The study for installing noise barrier on highway route no.9

Scipedia content — Mon, 22 Mar 2021 19:45:37 +0100

Highway Route No. 9 is a Bangkok bypass motorway that aims to alleviate traffic congestion in greater Bangkok areas. Presently, it is found a rapid expansion of new communities residing along both side of Highway No. 9. To lessen the noise level, Department of Highways installed the noise barrier on the sensitive locations. However, people from communities living on both sides of highway still demand some additional noise pollution improvement. To improve the efficiency of using noise barriers and to promote environmental and social quality for the people on the sensitive communities along the highway route, the Department of Highways, therefore, designs a new technique for installing noise barrier on the sensitive areas, i.e. education institutions, temple, residential area. In addition, the mathematic model is applied to 12 selected locations of sensitive areas for monitoring the effectiveness of the new installation technique. The mathematic model is used for predict the future noise level after installation of noise barrier in year 2037. The results confirm that the appropriate height and width of noise barrier can improve the comfortable of the people on the sensitive area.

Document type: Article

Group Gap Acceptance: A New Method to Analyze Driver Behavior and Estimate the Critical Gap at Multilane Roundabouts

Scipedia content — Mon, 22 Mar 2021 19:39:22 +0100

The operations of multilane roundabouts, especially three-lane roundabouts, are unique and more complicated than any other type of roundabouts. This study aims to analyze driver behavior and estimate the critical gap at three-lane roundabouts. Video data were collected at two roundabouts. The analysis identified a pattern of group gap acceptance, where vehicles entering the roundabout from different lanes moved in groups during the same gap. In this case, the decision of vehicles entering from outside lanes greatly depended on the gap acceptance decision of vehicles in the inside lane. Analysis showed that the vast majority of the vehicles accept the gap in groups and the critical gap was estimated accordingly. The study provides a new explanation for the operation at multilane roundabouts. The use of this simple method is recommended when estimating critical gaps for multilane roundabouts. 2018 Khaled Shaaban and Hassan Hamad. This publication was made possible by the Qatar Research Fund (a member of Qatar Foundation) through an NPRP award [NPRP 4-1170-2-456]. Scopu

Document type: Article

Ecozanja: una nueva solución de zanja basada en la reutilización de material excavado y una capa de hormigón expansivo

Scipedia content — Mon, 22 Mar 2021 19:31:11 +0100

Installing utility pipelines generates a significant amount of trench arisings, which are usually transported to landfills instead of being reused as backfill material. This practice generates CO2 emissions and wastes raw materials. This paper presents a more sustainable solution, an eco-trench, which is based on re-using trench arisings as backfill and adding a top layer of expansive concrete to improve the eco-trench’s structural performance. The technical feasibility of the eco-trench was evaluated through a finite element model, which identified the degree of expansion in concrete required to avoid failure or subside the stresses caused by traffic. The potential expansion of concrete was measured under confined conditions in the laboratory by means of a novel test developed for this purpose. The results showed that adding calcium oxide generates the required internal stress. The results were then confirmed in a pilot experience.

Las zanjas para instalaciones de servicios generan un elevado volumen de materiales de excavación que son transportados a vertederos en lugar de ser reaprovechados como relleno. Esto conlleva un mayor consumo de materias primas y emisiones de CO2 asociadas al transporte. Este estudio presenta una solución más sostenible, denominada ecozanja, basada en la reutilización de los materiales de excavación como relleno de la zanja con una capa superficial de hormigón expansivo. Su aplicabilidad se evalúa mediante un modelo de elementos finitos que permite determinar el grado de expansión necesario en el hormigón para garantizar la resistencia de las tensiones debidas al tráfico de vehículos sobre la zanja. La expansividad del hormigón se evaluó mediante un ensayo desarrollado específicamente para tal objetivo. Los resultados indican que la adición de óxido de calcio genera las tensiones internas necesarias. Asimismo, la propuesta se validó mediante una experiencia piloto en obra.

Document type: Article

Assessment of Single European Sky Implementation in the Functional Airspace Block Central Europe

Scipedia content — Mon, 22 Mar 2021 19:26:15 +0100

Implementation of Air Traffic Management (ATM) MasterPlan-defined projects represents a prerequisite for thesuccessful implementation of the Single European Sky initiativedefined by the European Commission in 2004. Theimplementation of ATM-related projects is currently under the responsibility of the Single European Sky Research Programme Deployment Manager. While the definition of projects is being performed at the European Network level, theimplementation is performed through sub-regional grouping of Air Navigation Service Providers in a form of Functional Airspace Blocks. This paper analyses the level of implementation of ATM-related projects in the Functional Airspace Block Central Europe and their relation to other Functional Airspace Blocks defined in Europe. From this paper it is obvious that even though the planning of Single European Sky projects is based on the collaborative implementation of Functional Airspace Block level, the real implementation is fragmented and based on national levels.

Document type: Article

A CPN/B method transformation framework for railway safety rules formal validation

Scipedia content — Mon, 22 Mar 2021 19:24:26 +0100

This paper presents a 'CPN/B method' based process for railway systems safety analysis. Achieving interoperability through the European Rail Traffic Management System (ERTMS/ETCS) is facing difficulties in railway safety assessment due to the interaction of national and European operating specifications. These specifications have been modeled using several formalisms, which makes it is extremely hard to preserve all requirements when switching between different formalisms. However, this problem, crucial for efficient progress in railway safety research, has received very little attention in the literature. In this respect, the purpose of this contribution is to provide a methodology to demonstrate safety in railway systems by converting CPN models, widely used in modeling, into B abstract machines. It aims at enabling a stronger combination of formal design techniques and analysis tools able to cope with the real complexity of systems and automatically prove that safety properties are unambiguous, consistent and not contradictory, considering an industrial railway context.

Document type: Article

Hierarchical Agglomerative Clustering Schemes for Energy-Efficiency in Wireless Sensor Networks

Scipedia content — Mon, 22 Mar 2021 19:24:03 +0100

"jats:p" Extending the lifetime of wireless sensor networks (WSNs) while delivering the expected level of service remains a hot research topic. Clustering has been identified in the literature as one of the primary means to save communication energy. In this paper, we argue that hierarchical agglomerative clustering (HAC) provides a suitable foundation for designing highly energy efficient communication protocols for WSNs. To this end, we study a new mechanism for selecting cluster heads (CHs) based both on the physical location of the sensors and their residual energy. Furthermore, we study different patterns of communications between the CHs and the base station depending on the possible transmission ranges and the ability of the sensors to act as traffic relays. Simulation results show that our proposed clustering and communication schemes outperform well-knows existing approaches by comfortable margins. In particular, networks lifetime is increased by more than 60% compared to LEACH and HEED, and by more than 30% compared to K-means clustering.

Document type: Article

Traffic state estimation using floating car data

Scipedia content — Mon, 22 Mar 2021 19:18:30 +0100

There is an increasing availability of floating car data both historic, in the form of trajectory datasets and real-time, in the form of continuous data streams. This paves the way for several advanced traffic management services such as current traffic state estimation, congestion and incident detection and prediction of the short-term evolution of traffic flow. In this paper, we present an analysis of using probe vehicles for reconstructing traffic state. We employ detailed agent-based microscopic simulations of a real world expressway to estimate the state from floating car data. The probe penetration required for accurate traffic state estimation is also determined.

Document type: Article

Road Traffic Congestion Management Based on a Search-Allocation Approach

Scipedia content — Mon, 22 Mar 2021 19:16:05 +0100

"jats:p"This paper introduces a new scheme for road traffic management in smart cities, aimed at reducing road traffic congestion. The scheme is based on a combination of searching, updating, and allocation techniques (SUA). An SUA approach is proposed to reduce the processing time for forecasting the conditions of all road sections in real-time, which is typically considerable and complex. It searches for the shortest route based on historical observations, then computes travel time forecasts based on vehicular location in real-time. Using updated information, which includes travel time forecasts and accident forecasts, the vehicle is allocated the appropriate section. The novelty of the SUA scheme lies in its updating of vehicles in every time to reduce traffic congestion. Furthermore, the SUA approach supports autonomy and management by self-regulation, which recommends its use in smart cities that support internet of things (IoT) technologies.

Document type: Article

Review of hybrid laminar flow control systems

Scipedia content — Tue, 16 Feb 2021 13:45:50 +0100

The aeronautic community always strived for fuel efficient aircraft and presently, the need for ecofriendly aircraft is even more, especially with the tremendous growth of air traffic and growing environmental concerns. Some of the important drivers for such interests include high fuel prices, less emissions requirements, need for more environment friendly aircraft to lessen the global warming effects. Hybrid laminar flow control (HLFC) technology is promising and offers possibility to achieve these goals. This technology was researched for decades for its application in transport aircraft, and it has achieved a new level of maturity towards integration and safety and maintenance aspects. This paper aims to give an overview of HLFC systems research and associated flight tests in the past years both in the US and in Europe. The review makes it possible to distinguish between the successful approaches and the less successful or outdated approaches in HLFC research. Furthermore, the technology status shall try to produce first estimations regarding the mass, power consumption and performance of HLFC systems as well as estimations regarding maintenance requirements and possible subsystem definitions.

Policy developments for the reduction of climate change impacts by the transportation sector

Scipedia content — Tue, 16 Feb 2021 13:45:13 +0100

Ekici, Şule Önsel (Dogus Author) -- Özaydın, Özay (Dogus Author) The transportation sector is one of the most significant sources of anthropogenic greenhouse gas emissions. In order to mitigate climate change, it is important to apply effective and immediate policies to reduce the transportation sector's emissions. This study aims to: (1) define the dimensions of the transportation sector, such as its environmental, economic, social, and political elements, and (2) investigate how they relate to climate change, in order to assess potential mitigation scenarios and policies that could reduce the sector's contribution to climate change. First, sector-related variables were specified using expert opinions and a literature survey. Relationships between the variables and the associated intensity values were then identified using document coding, as well as by gathering expert opinions through a workshop. A fuzzy cognitive map analysis was then conducted to investigate the relationships between the variables and the resulting impacts by the transportation sector on climate change. A scenario analysis was also conducted in order to identify the most effective policies in reducing the impacts of transportation on climate change, at both the local and global levels. For the scenario analysis at the global level, projections by the International Energy Agency were analyzed through the model. The local policy suggestions developed by Turkish authorities were also evaluated using scenario analysis.

Exploring the suitability of electric vehicles in the United States

Scipedia content — Tue, 16 Feb 2021 13:40:22 +0100

This study explores suitability of battery electric vehicles in the United States by considering their potential market share and operations costs as well as the state-specific variations in electricity generation profiles, given current government policies and the social acceptability of the technology. A performance assessment is developed to compare each state and identify major policy efforts that are needed to increase the environmental and economic competitiveness of electric vehicles. A novel multi-criteria decision-support framework, integrating Life Cycle Assessment, Data Envelopment Analysis, and Agent Based Modeling, is developed. To this end, the environmental and economic impacts of battery electric vehicles are calculated based on three scenarios: an average electricity generation mix, a marginal electricity generation mix, and a solely renewable energy mix with 100% solar. The states are classified, each requiring different policy strategies, in accordance with their performance scores. The results provide important insights for advancing transportation policies and a novel framework for multi-criteria decision-making in the future analyses.