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The Third International Conference on Computational Science and Engineering (ICCSE-3)28-30 November, 2016, Ho Chi Minh City, Vietnam

INVITED TALKS

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I3.1

Descent and Cutting Surface Methods for Nonsmooth Equilibrium Problems

MAURO PASSACANTANDOUniversity of Pisa, Department of Computer Science, Italy

Email: [email protected]

The abstract equilibrium problem (EP) provides a rather general setting which includes several mathematical models such as optimization, variational inequalities, fixed point and complementarity problems, Nash equilibria in noncooperative games. In this talk, we describe two classes of algorithms for solving nonsmooth EPs. The talk is divided into two parts. The first part is devoted to the gap function approach for EPs with locally Lipschitz data. The gap function inherits the locally Lipschitz continuity of the data. Hence, the connections between its generalized directional derivatives, monotonicity conditions on the equilibrium bifunction and descent properties, can be analysed. In turn, this analysis leads to devise two globally convergent descent methods. The second part of the talk is devoted to a class of cutting surface methods for EPs.It is well-known that a pseudomonotone EP is equivalent to minimize the so-called Minty gap function. Though it is a convex function, it can be difficult to evaluate since this requires to solve non-convex optimization problems. We develop cutting surface methods for solving EP via the Minty gap function, relying on lower convex approximations which are easier to compute. These methods require to solve a convex optimization problem at each iteration and their convergence is proved under suitable monotonicity assumptions.Finally, the results of some preliminary numerical tests are reported.

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mailto:[email protected]


I3.2

Modeling Bedload Transport of a Coral Gravel Beach

YOSHIMITSU TAJIMADepartment of Civil Engineering, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo, Japan


Ultimate goal of this study is to develop a process-based numerical model for predictions of cross-shore morphology change of a coral gravel beach. Incident waves may be breaking, broken and running up on a porous gravel bed and the transport of coral gravels with relatively smaller density may be highly affected by forward-leaning profiles of wave orbital velocity. This study first carried out laboratory experiment1,2 focusing on physical characteristics of transport of coral gravels under the forward-leaning nearshore waves (Figure-1). Image-based analysis was applied to extract various quantitative characteristics such as: water surface fluctuations; forward-leaning wave orbital velocity fields; and time-varying locations of moving coral gravels under the waves. The water was colored in blue so that the fluctuating water level inside the porous layer of coral gravel bed can also be captured.A phase-resolved non-linear dispersive wave model was then developed with a breaking model applicable to both progressive and partial standing waves and also with porous model for estimations of the wave penetration into the coral gravel bed. Process-based bedload sediment transport model was then applied for estimation of the moving velocity of the coral gravels3. Inertia force acting on the gravels was newly added in the conceptual model and it was found through comparisons with the experiments, as shown in Figure 2, that inertia force plays important role for determination of coral gravels especially under the front face of the forward leaning waves around the surf zone and swash zone.

Figure 1. (a) Experimental setups; (b) captured image of the experiment; and (c) coral gravels.

Figure 2. Cross-shore profiles of water surface levels respectively at two different phase conditions (black solid lines) and landward velocity of moving gravels (meas: solid bars and predictions when fluid acceleration force (inertia force) was accounted for (red line) and not (blue dashed line).

Keywords: Coral Gravels, Wave Breaking, Forward-leaning Wave, Bedload Transport

References[1] Y.Tajima and H. Fujikawa, Journal of JSCE B3, 2016, vol.72 (2), pp.I_904-909. (in Japanese).[2] Y.Tajima and S. Seto, Proc. Int. Conf. Coastal Dynamics, 2017 (printing).[3] Y.Tajima and H. Fujikawa, Journal of JSCE B2, 2016, vol.72 (2) (in Japanese).

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I3.3

Computational Modeling of Materials Corrosion in Liquid Metals for Nuclear Reactors Application

TAKUJI ODA*, JEONGHWAN HAN, JUNHYOUNG GILDepartment of Nuclear Engineering, Seoul National University, Korea


Liquid metals such as liquid Na and liquid Pb-Bi eutectic (LBE) are considered as promising coolant materials for advanced nuclear reactors. For utilization of liquid metals, materials corrosion is one of the key issues. In previous studies, in order to understand the corrosion mechanism, the solubility of components of structural materials were evaluated, and microstructures of corroded materials were analyzed. However, agreement in reported solubility data are not good and the corrosion mechanisms is yet to be sufficiently understood. In the present study, we perform first-principles molecular-dynamics calculation to investigate the chemical states and stabilities of important elements, such as Fe, Ni, Cr, C and O, in liquid LBE. We analyze configurational and electronic properties of these impurity elements in liquid LBE. As a result, we found that there are characteristic trends in the atomic size, the coordination number and electronic states of 3d and 2p elements in liquid LBE. Based on the calculation results and in comparison with available experimental data, a model to explain chemical stabilities of impurity atoms in liquid LBE is proposed. In the presentation, we will also discuss how to accurately determine important material properties such as solubility and diffusivity in liquid metals by means of multi-scale modeling techniques.

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I3.4

An Extragradient-Type Method for Solving Non-Monotone Equilibrium Problems in Hilbert Spaces

JEAN JACQUES STRODIOTDepartment of Mathematics, University of Namur, Belgium


A new class of extragradient-type methods is introduced for solving an equilibrium problem in a real Hilbert space without any monotonicity assumption on the equilibrium function. The strategy is to replace the second projection step in the classical extragradient method by a projection onto shrinking convex subsets of the feasible set. Furthermore, to ensure a sufficient decrease on the equilibrium function, a general Armijo-type condition is imposed. This condition is shown to be satisfied for four different linesearches used in the literature. Then, the weak and strong convergence of the resulting algorithms is obtained under non-monotonicity assumptions. Finally, some numerical experiments are reported.

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I3.5

Metaheuristic Methods for the Open Pit Production Scheduling Problem with Metal Uncertainty

JACQUES A. FERLANDDepartment on Computer Science and Operation Research (DIRO), Univeristy of Montreal, Canada


Uncertainty is an inherent aspect of the open pit mine production scheduling problem (MPSP); however little is reported in the literature about solution methods for the stochastic versions of this problem, but recently more research is completed on it. This presentation will outline a mathematical programming model for this MPSP with metal uncertainty, and an approach combining exact and metaheuristic methods to deal with it. Moreover, more complex and realistic versions of the problem are also discussed where adaptive neighborhood search techniques are required to obtain good results in reasonable computer time.

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I3.6

Interior Transmission Eigenvalues and Non-Destructive Testing

ANDREAS KLEEFELDInstitute for Advanced Simulation, Jülich Supercomputing Centre, Forschungszentrum Jülich GmbH, Germany


The aim in non-destructive testing is to visualize the interior of a given three-dimensional object in order to uncover location, size, and geometry of inhomogeneities. Interior transmission eigenvalues can be used for this purpose. However, the efficient numerical calculation of interior transmission eigenvalues is a challenging task due to the fact that the corresponding interior transmission problem is neither elliptic nor self-adjoint. It is explained what interior transmission eigenvalues are, how they can be computed to high accuracy with the help of boundary integral equations (see [1-3]), and how they might be used to visualize the interior of a given three-dimensional object. Additionally, some open problems both from the theoretical and practical point of view are illustrated.

Keywords: Interior Transmission Eigenvalue, Helmholtz Equation, Boundary Integral Equation, Boundary Element Collocation Method, Nondestructive Testing

References[1] Andreas Kleefeld, Inverse Problems 2013, 29, 104012 (20pp).[2] Andreas Kleefeld, Numerical methods for acoustic and electromagnetic scattering: Transmission boundary-

value problems, interior transmission eigenvalues, and the factorization method, Habilitation Thesis, May 2015.

[3] Andreas Kleefeld, 12th international conference on mathematical aspects of wave propagation, Karlsruhe Institute of Technology, 20-24 July 2015, pp. 276-277.

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I3.7The Experiences of Shared Transportation Service in Korea

CHUNGWON LEESeoul National University, Department of Civil & Environmental Engineering, Korea


Sharing economy is recently spreading in all around the world. Among them, transportation sector takes the majority of its portions. Several years ago, shared transportation service was introduced in South Korea, mainly in metropolitan areas. Currently, there is a carsharing service known as ‘NanumCar’ operated by a private company with the support of Seoul Metropolitan Government. ‘SoCar’ is considered as the most leading company in car sharing service in Korea. Moreover, service called ‘Happy Car’ that LH (Korea Land & Housing Corporation) provided for those people who live in rental housing is growing up rapidly. KORAIL (Korea Railroad), Korean railway operator, also offers a carsharing service, called ‘YouCar’ at most of high speed rail transit stations. Additionally, parking space sharing service has been appeared for solving the problem of parking space shortage in the metropolitan area. ‘Moduparking’ is a typical example of parking space sharing service. However, even though the cause has not been properly identified yet, carpool service, considered as traditional shared transportation service, is still not actively operated in Korea.Meanwhile, Uber, the largest shared transportation service company in the world, was introduced in Korea. However, Uber service has been ceased because its service was regarded as illegal under the current law. This study introduces the status of shared transportation services and the current issues. In the metropolitan areas of South Korea, the public transport system is highly developed and IT infrastructure is well established. In addition, there are a lot of choice riders of public transport. Therefore, it is expected that shared transportation service can be developed as a major service of MaaS (Mobility as a Service) in the near future along with autonomous vehicle, eco-friendly vehicles (e.g. electric vehicles), personal mobilities, etc.

Keywords: Sharing Economy, Carsharing, Carpool, MaaS

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I3.8

Introduction on Development of EDISON(Education-Research-Industry Integration through Simulation On the Net)

JONGSUK RUTH LEESupercomputing R&D Center, National Institute of Supercomputing and Networking (NISN),

Korea Institute of Science and Technology Information (KISTI), KoreaEmail: [email protected]

The ripple effect of the high performance computer and network in the 21st century has been accelerated by implementing a cyber infrastructure with them. Many people from various sectors are also now talking about “Smart” and “Ubiquitous” things for workplaces, homes, school classrooms, and so on. Terms of ubiquitous and smart are another words for everywhere and intelligence. Ubiquitous smart learning can be defined as a quite innovative way of getting the knowledge, especially in advanced science and engineering areas. Ubiquitous learning environments are always connected to the Internet and provide a learners' paradise where they can learn anywhere and anytime whatever they want to learn.

This paradigm has already rapidly been changing people's everyday life including education, research, entertainment, and so on. The developed countries such as the US and the EU have tried to apply the R&D accomplishments of advanced science and engineering technology to realize the paradigm especially in higher education to strengthen students’ competitiveness in science and engineering technology. To this end, those countries operate a nanoHUB project for the education of nano technology in the US. There are also the ICLCS (Institute for Chemistry Literacy and Computational Science) project for the education of Chemistry, the ICEAGE (International Collaboration to Extend and Advance Grid Education) project for the education of grid computing technology, the hpc2 (High Performance Computing Consortium), and so on. The Korean government has also started to fund a project to build and provide a computer simulation-based ubiquitous smart learning environment for college students in science and engineering fields from 2011.

In this paper, we have investigated the status, trends and problems of Korea's current R&D and higher education especially in the science and engineering areas. We will also suggest how to build the future oriented education environment that is basically a computer simulation-based learning environment. We will also introduce a system called EDISON (EDucation-research-industry Integration through Simulation On the Net) which is currently used for research and education in Korea. EDISON is a computer simulation-based learning and researching system. The EDISON system could be used by the curious learner, much like Thomas Alva Edison who lived in the 19th century and liked to do all kinds of experiments to verify or discover answers to his curiosities or to solve problems. We, smart learners, who are living in the 21st “smart century” can do many experiments like those done by Edison through computer simulations in a ubiquitous smart learning environment using the EDISON system.

Fig. 1 shows EDISON portals of five areas based on the EDISON platform version 2.0 in CFD (Computational Fluid Dynamics), NanoPhysics, computational Chemistry, CSD (Computational Structural Dynamics), and CAD (Computer Aided optimal Design). Users of these areas connected to the Internet can run their simulation jobs by taking the easy steps on http:// www .edison.re.kr/ . Our current EDISON system has been used by 38,849 users in Korea since July 2011. User evaluation of the system is very positive. They think the system is very useful and helpful to understand difficult theories in an easy manner. The EDISON system will be added more functionalities for the users’ better support and will be deployed to other communities such as computational medicine, and so on.

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http://www.edison.re.kr/



Figure 1. Screen Shot of EDISON Main Portal and Five Areas’ Sub-Portals

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[EDISON Main Portal]

[CFD] [NanoPhysics]

[Chemistry]

[CSD] [CAD]


I3.9

Genetic Algorithms: an Evolutionary Approach to Optical Engineering

ALEXANDRE MAYERDepartment of Physics, University of Namur, Namur, Belgium


Nature has developed its own algorithms to determine optimal solutions. With genetic algorithms, we mimic natural selection in order to determine the optimal parameters of complex problems in physics. The idea consists in working with a virtual population of individuals. Each individual is representative of a given set of physical parameters for the objective function we seek at optimizing. The initial population usually consists of random individuals. The best individuals are then selected. They generate new individuals for the next generation. Mutations in the coding of parameters are finally introduced. When repeated from generation to generation, this evolutionary strategy makes it possible to determine the global optimum of a problem. This approach is especially adapted to parallel computing techniques. It will therefore take full advantage of the thousands of cores typically present on modern supercalculators. This enables an application of genetic algorithms to real-world problems for which the objective function is computationally expensive. The applications considered in this presentation will include the optimization of the light-extraction efficiency of light-emitting diodes [1], the optimization of solar thermal collectors by a multi-objective genetic algorithm [2], and the optimization of the optical efficiency of thin-film crystalline-silicon photovoltaic panels [3].

Keywords: Genetic Algorithm, Optimization, Engineering, Light Emitting Diode, Photovoltaics, Solar Thermal Collector

References:[1] Alexandre Mayer and Annick Bay, Journal of Optics 2015, 17, 025002.[2] Alexandre Mayer, Lucie Gaouyat, Delphine Nicolay, Timoteo Carletti and Olivier Deparis, Optics Express 2014, 22, (S6), A1641- A1649.[3] Alexandre Mayer, Jérôme Muller, Aline Herman and Olivier Deparis, Proc. of SPIE, 2015, 9546, 95461N-

01.

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CONTRIBUTED TALKS

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O3.1

The Stable Method for Approximating Values of Unbounded Operators

NGUYEN VAN KINHFaculty of General Science, Ho Chi Minh University of Food Industry, Ho Chi Minh City, Vietnam


Unbounded operators can transform arbitrarily small vectors into arbitrarily large vectors -- a phenomenon known as instability (see [6]). Stablization methods strive to approximate a value of an unbounded operator by applying a family of bounded operators to rough approximate data that do not necessarily lie within the domain of the unbounded operators.The stable computation of values of unbounded operators is one of the most important problems in computational mathematics. This problem has been taken into consideration by mathematicians over the years (see [4]).In the case, where is a closed densely defined unbounded linear operator from a Hilbert space into a Hilbert space , V. A. Morozov, C. W. Groetsch and O. Scherzer have studied a stable method for

approximating the value when only approximate data is available (see [1, 5]). This method takes as an

approximation to the element , where minimizes the parametric functional

.

They show that, if as , in such a way that , then as δ→0.

In another case, where is a monotone operator from a real strictly convex reflexive Banach space into its

dual , an approximation to is the element , where is the unique solution of the equation

,

where is the dual mapping in . Then the sequence for , in the norm

of , to a generalized value of the operator at (see [3]).

In this paper we assume that both the operator and are only given approximately by and

, which satisfy

and (*)We shall be concerned with the construction of a stable method of computing values of the operator A for the perturbations (*) (see [2]) in the following cases:1) is a closed densely defined unbounded linear operator from Hilbert space into Hilbert space .

2) is a monotone operator from a real strictly convex reflexive Banach space into its dual .

References[1] C. W. Groetsch and O. Scherzer, The optimal order of convergence for stable evaluation of differential

operators, Elec. J. Diff. Eqns. 4, 1993.[2] Nguyen Van Kinh, On the stable method of computing values of unbounded operators, Journal of Ho Chi

Minh City University of Food Industry, 2014, No. 2.

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[3] Ya. I. Al'ber and P. Ryazantseva, Solution of nonlinear problems involving monotonic discontinuous mapping, Diff. Uravneniya, 1979, 15(2).

[4] C. W. Groetsch, Stable approximate evaluation of unbounded operators, Springer, 2007.[5] V. A. Morozov, Methods for solving incorrectly posed problems, Springer-Verlag, New York, 1984.[6] A. N. Tikhonov and V. Ya. Arsenin, Methods of solving incorrectly posed problems, Nauka, Moscow, 1971 (in Russian).

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O3.2

A Posteriori Error Estimation for Pseudo Differential Equation on Spheres

with Spherical Splines

DUONG T. PHAM1,*, TUNG LE1

Computational Engineering Program, Vietnamese German University, Binh Duong, VietnamEmail: [email protected]

We prove a posteriori upper and lower bounds for the error estimates when solving the Laplace--Beltrami equation on the unit sphere by using Galerkin method with spherical splines. Adaptive mesh refinements based on these a posteriori error estimates are used to reduce complexity and computational cost of the corresponding discrete problems. The theoretical results are corroborated by numerical experiments.

Keywords: Laplace--Beltrami equation, spherical spline, finite element methods, a posteriori error estimate, adaptivity

References [1] Pham, Duong; Tran, Thanh. A Domain Decomposition Method for Solving the Hypersingular Integral

Equation on the Sphere with Spherical Splines. Numer. Math. 120 (2012), no. 1, 117-151, 65R20 (45E05).[2] Pham, Duong; Tran, Thanh and Crothers, Simon. An Overlapping Additive Schwarz Preconditioner for The

Laplace-Beltrami Equation Using Spherical Splines. Adv Comput Math (2012), 37:93-121. [3] Pham, T. D.; Tran, T.; Chernov, A. Pseudodfferential Equations on the Sphere with Spherical Splines.

Math. Models Methods Appl. Sci. 21 (2011), no. 9, 1933-1959, 65N30 (35S15 41A15).

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O3.3

Sequential Optimality Conditions for Simple Convex Bilevel Programming Problems

VO DUC THINH, NGUYEN KIM NGAN2,*

Department of Mathematics & Informatics Teacher Education, Dongthap UnviersityEmail: [email protected] (VDT) , [email protected] (NKN)

In this paper, we provide sequentially necessary and sufficient conditions for weak Pareto solutions of convex multiobjective programming problems. Then we establish sequentially necessary and sufficient conditions for weak Pareto solutions of simple convex bilevel programming problems which do not attach constraint qualifications.

Keywords: Sequential optimality condition, weak Pareto solution, convex multiobjective programming, simple convex bilevel programming.

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O3.4Subaqueous Gravity Flow of Thixotropic Fluid

KHOA LE-CAO1,*, THANH TRAN-CONG2, NANCY CHAN HUI CHING3, KHOO BOO CHEONG 1, NHAN PHAN-THIEN 1

1Department of Mechanical Engineering, National University of Singapore, Singapore 2Computational Engineering and Science Research Centre, School of Mechanical and Electrical Engineering,

University of Southern Queensland, Toowoomba, QLD 4350, Australia3Offshore Engineering Laboratory, Fugro Southeast Asia Group, Singapore


In this research work, interactions between a thixotropic fluid (i.e., bentonite clay mixture) and water are numerically investigated. Thixotropic fluid is a fluid with a rheology dependent on (i.e., functionals of) the fluid microstructure. Depending on the flow kinematics, the fluid microstructure may break up in regions of high shear and then restore at low shear zones. In [1-2], the local degree of fluid microstructures is represented by a non-dimensional structural parameter λ (t) . The structural parameter λ (t) varies between 0 and λ0 and is an indication of the integrity of the microstructures network (λ=0: no network; λ=λ0: fully developed network). The microstructure network needs time to build up and to rupture, and thus the rheology of the mixture has a time scale. The time dependence rheology properties for bentonite clay mixtures are determined through a batch of tests using HAAKE MARS III Rotational Rheometer. Experimental results show that the yield stress and viscosity increase with resting time. Time evolution equation of λ (t) is solved in a coupling manner with Navier-Stokes equations by employing Smoothed Particle Hydrodynamics (SPH) method. Numerical results regarding the effect of resting time to the density flow profiles are reported.

Figure 1. Density profile of bentonite mixture (red colour) at t = 0.5s for subaqueous gravity flow on a 450 slope.

Keywords: Structural kinematic model, Numerical simulation, Rheology, SPH, Subaqueous flows

References[1] P. Coussot, A.I. Leonov, J.M. Piau, Rheology of Concentrated Dispersed Systems in a Low Molecular

Weight Matrix, Journal of Non-Newtonian Fluid Mechanics 1993, 46, 179-217.[2] E. A. Toorman, Modelling the Thixotropic Behaviour of Dense Cohesive Sediment Suspensions, Rheologica

Acta 1997, 36, (1), 56-65.

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O3.5

Study of a Sediment Suspension Jet in Quiescent Water using Smoothed Particle Hydrodynamics: Application to Deep-Sea Mining Tailing

Discharge

THINH XUAN HO1,*, NHAN PHAN-THIEN1, BOO CHEONG KHOO1

1Department of Mechanical Engineering and Keppel-NUS Corporate LaboratoryNational University of Singapore, Singapore


Polymetallic nodule harvesting from the deep-sea seabed may involve a vertical transport of slurry from the seabed to a surface platform where slurry processing takes place. The nodule material is retained at the surface while other solid materials including sediment, sand and gravels are returned to the seabed, i.e. a so-called tailing discharge process. This process creates a sedimentary plume, which may spread to a considerable distance and stay in the water column for a considerable time before re-settling back on the sea floor. It is therefore important to predict its spreading and sedimentation rate in order to be able to minimize the environmental impact.In this work, the tailing discharge process is represented by a jet flow of sediment suspension pumped into quiescent water. We investigate the effects of sediment concentration, flow rates, Reynolds number, etc. on the dispersion of sediment. A two-fluid model has been adopted into the open-source code SPHysics [1-2] with necessary modifications to account for the sediment suspension phase and for the interaction between it and the pure water phase. This code is based on Smoothed Particle Hydrodynamics (SPH), a meshless method which solves fluid flows using a Lagrangian approach [3]. Preliminary results show good agreement with experimental data available in the literature. A typical result obtained from a two-dimensional simulation is shown in Figure 1. This is an ongoing work; the further work would include fully three-dimensional simulations.

Figure 1. Sediment suspension jet at t=0.05s, 0.1s, 0.15s (from left to right); red for a volume fraction of sediment of =0.2, blue for pure water. The jet Reynolds number is Re=148.

Keywords: SPH, Sediment Dispersion, Tailing Discharge, Two-fluid Model, Multiphase Flow

References[1] Gómez-Gesteira M., Rogers B.D., Crespo A.J.C., Dalrymple R.A, Narayanaswamy M. and Dominguez J.M.,

Computers & Geosciences 2012, DOI:10.1016/j.cageo.2012.02.029.[2] Gómez-Gesteira M., Crespo A.J.C., Rogers B.D., Dalrymple R.A., Dominguez J.M. and Barreiro A.,

Computers & Geosciences 2012, DOI:10.1016/j.cageo.2012.02.028.[3] Gingold R.A., Monoghan J.J., Monthly Notices of the Royal Astronomical Society 1977, 181, 375-89.

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O3.6

Recovery-Based Discontinuous Galerkin for Diffusion

MARCUS LO1, BRAM VAN LEER2, AND LOC KHIEU3,4*

1&2Arthur B.Modine Emeritus Professor, Aerospace Engineering3Research Collaborator, Institute for Computational Science and Technology (ICST), Ho Chi Minh City,

Vietnam4Lecturer, Computational Engineering, Vietnamese-German University (VGU), Binh Duong, Vietnam


The Recovery-based Discontinuous Galerkin method (RDG) for linear diffusion-shear problems is shown on Cartesian grid to achieve the order of accuracy 3 p+2 for even p and 3 p+1 for odd p, where p≥1 is the order of the polynomial basis. The RDG method incorporates a solution-enhancement step that reuses the recovery results, and an extra recovery step based on the enhanced solution. Thus, the stencil is extended not only to an element’s face-sharing neighbors but also to the vertex-sharing ones. The order-of-accuracy results obtained via Fourier analysis are numerically verified.

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O3.7

Numerical Simulation of Laminar Free Convective Flow in Vertical Solar Chimneys Using Lattice Boltzmann Method

Y QUOC NGUYENDepartment of Civil Engineering, Ho Chi Minh City University of Technology, Vietnam


Solar chimney is a device for natural ventilation of buildings based on stack effects. A typical solar chimney consists of a glass plate, an air channel, and an absorber surface. Solar radiation heat is transmitted through the glass plate and absorbed by the absorber surface. Convective heat transfer from the absorber surface to air inside the channel induces thermal effects and accordingly airflow through the channel. Therefore, buoyancy force is the main driving force for this device. In order to study the free convective flow inside vertical solar chimneys, I use Lattice Boltzmann Method with the BGK collision model. The flow was described by the D2Q9 model while the temperature field was simulated with the D2Q4 model. Different temperature values were assigned to the glass and the absorber surface as boundary conditions. Simulations were conducted for Rayleigh number based on the channel height from 103 to 106. Simulation results were validated by published data and then examined to offer details of the flowfield and heat transfer inside the channel. Keywords: Thermal Effects, Free Convection, Lattice Boltzmann Method, Solar Chimney, Natural Ventilation

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O3.8

2D Numerical Simulations of Fine Bubble Flow in Straight Pipes

TAEYOON LEE*, VAN THINH NGUYENDepartment of Civil and Environmental Engineering, Seoul National University, Seoul, Korea

Email: [email protected] (TL); [email protected] (VTN)

The main purpose of water aeration is to maintain healthy levels of dissolved oxygen (DO) concentration. Water aeration involves the injection of air or air bubbles into water treatment reservoir commonly through pipes. Fine bubble has higher mass transfer when its diameter is getting smaller and smaller. Such fine bubbles are more capable of enhancing DO concentration level. However, there are only a few studies that deal with the relationship between mathematical characteristics of two-phase flow inside horizontal pipe and DO concentration level. The main objective of this study is to perform 2-dimensional two-phase simulations inside horizontal pipe using the computational fluid dynamics OpenFOAM tools to examine the effect of pipe wall shear stress on bubble size, which is the major factor effecting DO concentration level. Under different initial conditions, two-phase numerical simulations using Reynolds-averaged Navier-Stokes combined with Eulerian-Eulerian method were carried out to compute the axial Sauter Mean Diameter (SMD) of bubbles, water velocity, and wall shear stress within a 13.4 m long horizontal pipe with 50.3 mm inner diameter. The coalescence and breakage of bubbles caused by random collisions were considered during the simulations to predict the values of axial SMD. The numerical results have been verified against the experimental data obtained from Yin et al. [2], Kocamustafaogullari and Wang [1], and the Water Supply Laboratory at Seoul National University. The water velocity and SMD were validated against the experimental data of Kocamustafaogullari and Wang [1] and the relative errors ranged from 4% to 15% and 8% to 30%, respectively. As a result, the increase of pipe wall shear stress will decrease bubble size and increase DO concentration. Therefore, it can be concluded that the pipe wall shear stress plays a key role in breaking up the bubbles.

Keywords: OpenFOAM, 2D CFD Modeling, Two-Phase Pipe Flow, Bubble Coalescence and Breakup, Sauter Mean Diameter, DO Concentration.

References[1] Kocamustafaogullari, G., & Wang, Z. An Experimental Study on Local Interfacial Parameters in a

Horizontal Bubbly Two-Phase Flow (1991) International Journal of Multiphase Flow, 17(5), 553-572.[2] Yin, Z., Zhu, D. Z., Cheng, D., & Liang, B. Oxygen Transfer by Air Injection in Horizontal Pipe Flow

(2013) J. Environ. Eng. Journal of Environmental Engineering, 139(6), 908-912.

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O3.9

Development of Webgis Integrated Remote Sensing Analysis to Assess Heat Island in Ho Chi Minh City

DUONG THI THUY NGAUniversity of Science, VNU-HCM Ho Chi Minh City, Vietnam


Satellite remote sensing has provided major advances in understanding the climate system and its changes, by quantifying processes and spatio-temporal states of the atmosphere, land and oceans. This paper introduces the remote sensing analysis of temperature, land cover types and WebGIS integrated remote sensing results to assess Heat island in Ho Chi Minh City. WebGIS application is carried out by utilizing and analysing the geospatial database. This study examined the effect of land cover types on urban heat distribution in Ho Chi Minh City. An urban heat island (UHI) is a city or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference usually is larger at night than during the day. The aim of this study is to analyze the surface temperature and assess the relationship between surface temperature and land cover types using WebGIS integrated remote sensing data. The research demonstrated the importance of urban development by characterizing the spatiotemporal variations in temperature associated with land cover types. Results from this study can expand our understanding of the relationship between surface temperature and land cover types, and provide insights for improving urban green space planning and management.

Keywords: Land Cover; Relationship; Remote Sensing; Temperature.

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O3.10

SNU Watershed Modelling Tool: A Case Study in Vietnam

HONG HA NGUYEN*, VAN THINH NGUYENDepartment of Civil & Environmental Engineering, College of Engineering, Seoul National University, South

KoreaEmail: [email protected]

An objective of this study is to introduce the Seoul National University Watershed Model (SNU-WS), and apply it to simulate a couples of watershed systems in Vietnam. SNU-WS is a GIS (Geographic Information System) based numerical software tool developed at the Computational Fluid Dynamics Laboratory of Seoul National University for assessment of water balance and runoff pollutions in watershed systems. The GIS-based numerical model makes watershed and water quality studies easier by bringing key data and analytical components under one GIS roof. With many of the necessary components together in one system, the analysis time is significantly reduced, a greater variety of questions can be answered, and data and management needs can be more efficiently identified. The watershed characterization component, working under an open source MapWindow GIS umbrella, allows users to quickly evaluate selected areas, organize and analyze information, and display results. The model tool is designed to facilitate all of scenarios because it incorporates tools that operate on both large and small watersheds. Minimum data requirements and effective application are advantages of this modeling tool. The model has been verified and validated against available well-known watershed models and observation data obtained from real applications for watershed systems in USA, Canada. In this study, we have adapted the model tool to apply for the Saigon-Dong Nai Rivers Watershed and the Tri An Watershed located in the Southeast of Vietnam. The numerical results show a reasonable agreement with the observation, even we have a limited available input data.

Keywords: GIS (Geographic Information System), watershed modeling, runoff, water balance, nutrient load.

References[1] MapWindow Open Source GIS Homepage (http://www.mapwindow.org/).

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http://www.mapwindow.org/


O3.11

Modelling the Single Chamber Solid Oxide Fuel Cell Behaviors by Artificial Neural Network

NGUYEN TUAN ANH1,*, NGUYEN THI ANH NGA2, LE MINH VIEN1

1Faculty of Chemical Engineering, Ho Chi Minh City University of Technology, Ho Chi Minh, Vietnam2Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh, Vietnam


As a clean and efficient energy conversion device, the fuel cell is currently considered as one of the most promising technologies for future energy demand. Solid oxide fuel cells (SOFCs) have several advantages over other types of fuel cells, including flexibility of fuel used and relatively inexpensive materials due to high temperature operation. Solid oxide fuel cell operated in the single-chamber mode exhibits several advantages over conventional single oxide fuel cell due to the simplified, compact, sealing-free cell structure. Mathematical models of SOFCs, developed to employ a system of multi-physical, chemical, and electrochemical equations, have been extensively applied to improve SOFC performance and design. The methods require knowledge about many parameters of the microstructure and electrochemical properties of the component materials, the system configuration, the exact multi-physicochemical processes and the numerical solutions, making for a complicated problem. An ANN can be used as a black-box tool to simulate systems without solving the physical equations merely by utilizing available experimental data. In this study, the ANN is used for modelling a singular cell behavior. The optimal network architecture is investigated. The error backpropagation algorithm was used for an ANN training procedure. Experiments of a planar button solid oxide fuel cell were used to train and verify the networks. The fuel cell system is fed by methane and oxygen. The cathode is LSCF6482, the anode is GDC-Ni, the electrolyte is LDM and the operating pressure is 1 atm. The ANN based SOFC model has the following input parameters: current density, temperature. Based on these input parameters, cell voltage is predicted by the model. Obtained results show that the ANN can be successfully used for modelling the single chamber solid oxide fuel cell. Based on the results from this study it can be concluded that, by using the ANN, an SOFC can be modelled with relatively high accuracy. In contrast to traditional models, the ANN is able to predict cell voltage without knowledge of numerous physical, chemical, and electrochemical factors.

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O3.12

Collision-induced Amplitude Dynamics of Optical Solitons in Broadband Nonlinear Optical Waveguides

QUAN M. NGUYEN1,*, AVNER PELEG2, TOAN T. HUYNH3

1Department of Mathematics, International University, Vietnam National University-HCMC, Vietnam2Department of Exact Sciences, Afeka College of Engineering, Tel Aviv 69988, Israel

3Department of Mathematics, University of Medicine and Pharmacy-HCMC, Ho Chi Minh City, VietnamEmail: [email protected]

We develop a propagation model consisting of a system of N perturbed coupled nonlinear Schrödinger (NLS) equations. We show that dynamics of soliton amplitudes in N-sequence transmission is described by N-dimensional Lotka-Volterra (LV) models. We study the stability and bifurcation analysis of the equilibrium points to stabilize soliton-sequence propagation and to achieve on-off and off-on transmission switching of M out of N soliton sequences. The results of numerical simulations with a system of N coupled nonlinear Schrödinger equations (2 ≤ N ≤ 4) show excellent agreement with the LV model’s predictions and stable propagation over significantly larger distances compared with other broadband nonlinear waveguides. We then discuss the reasons for the robustness of transmission stabilization and switching in waveguides with broadband delayed Raman response and narrowband nonlinear gain-loss.

Keywords: Multichannel Optical Waveguide Transmissions, NLS model, Optical Solitons, Lotka-Volterra Model

References [1] Q.M. Nguyen, A. Peleg, and T.P. Tran, Physical Review A , Vol. 91, 2015, 013839 [2] A. Peleg, Q.M. Nguyen, and T. T. Huynh, Stable Scalable Control of Soliton Propagation in Broadband Nonlinear Optical Waveguides, arXiv:1506.01124.

25


O3.13

Optimal Design of a Gravity-Balanced Compliant Exsokeleton for Motion Support of Human Arm

CHAU NGOC LE1, NGUYEN TAN THANG1, HO NHAT LINH1, THANH-PHONG DAO2,3*, LE HIEU GIANG1

1Faculty of Mechanical Engineering, Ho Chi Minh City University of Technology and Education, Vietnam2Division of Computational Mechatronics, Institute for Computational Science, Ton Duc Thang University, Ho

Chi Minh City, Vietnam3Faculty of Electrical & Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam


A motion support for human arm is a significant rehalibitation of muscular disabilities. This rehibility requires a continuous training exercise and a complete recover takes a long time and costs. To decrease the time and cost, a gravity-balanced compliant exsokeleton (GBCE) is proposed in this paper. Instead of using traditional rigid links connected with coil springs, the GBCE is constructed via using planar springs. The planar springs are designed via using the concept of compliant mechanism with flexure hinge. Hence, the total weight of GBCE is relatively light. The GBCE can move up or down in one degree of freedom and is supported by a grativy balancing mechanism to compensate the weight of human arm. Firstly, the finite element analys in ANSYS software is used to analyze the statics and dynamics of the GBCE. Among the specifications of the GBCE, the motion range is required as large as possible as so reach a goal-directed movement. To achieve a large motion range, the parameters of the planar springs are optimized via the Taguchi method. And then, the sensitivity analysis of the parameters of the planar springs is performed by the use of the response surface methodology. The results indicate that the the proposed gravity-balanced compliant exsokeleton can provide a motion enhancement of a human arm. The GBCE is expected to be used for arm rehalibitation at home.

Keywords: Compliant mechanism, gravity balance, exsokeleton, planar spring, optimization, sensitivity analysis.

Figure 1. Planar sprring is fabricated by using wire electrical discharged machining process

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O3.14

Optimization of Laminated Uniformly Distributed CNT-Reinforced Composite Square Plates for Maximum Fundamental Frequency Using

Differential Evolution Algorithm

VO-DUY TRUNG 1,2, TRUONG-THI TAM 1,2, NGUYEN-THOI TRUNG 1,2,*

1 Division of Computational Mathematics and Engineering, Institute for Computational Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam

2 Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, VietnamEmail: [email protected]

In this study, the layer optimization is carried out for maximizing the lowest (first) fundamental frequency of laminated uniformly distributed CNT composite square plates. The design variable is the fiber orientation in the layers. A smoothed finite element method named the cell-based smoothed discrete shear gap method (CS-DSG3) is employed for calculating the first natural frequencies of the composite plates with various layers and boundary conditions. Differential evolution algorithm (DE) is used for searching the optimal stacking sequences of the composite plates. In numerical examples, the laminated uniformly distributed CNT composite square plates with various parameters such as nanotube volume fraction, boundary condition, plate length/thickness ratio and number of layers are considered. The reliability and the accuracy of the CS-DSG3 for the free vibration analysis of the composite plates are demonstrated by comparing its numerical solutions with those of other available numerical results in the literature. Then, the optimum fiber orientation of the composite plates is computed and discussed.

Keywords: structural optimization, differential evolution algorithm (DE), numerical analysis, smoothed finite element method, carbon nanotube (CNT), composite material

27


O3.15

The Utility of Principal Component Analysis (PCA) for Confirming a Correlation Between the Multi-Element Composition and the Trans-

Resveratrol Content in Wine Samples

ELIZA BLICHARSKA1, PIOTR FLIEGER2,*, MALGORZATA TATARCZAK-MICHLEWSKA1, JOLANTA FLIEGER 1

1Department of Analytical Chemistry, Medical University, Lublin, Poland1Department of Medicine with Dentistry Division, Medical University, Lublin, Poland


Resveratrol as a main polyphenol discovered in grapes Vitis vinifera has been commonly evaluated in wines produced in different countries [1,2]. The cultivation system, the soil composition, technological processes have all affected also the metal contents in wines [3]. So far, quantification of stilbene derivatives and the metal content were performed independently. The aim of this work was to statistically examine relationship between resveratrol and metal concentration to provide appropriate evidence that these two parameters were linked. Correlation analysis with significant level (p < 0.05) and principal component analysis (PCA) were performed by statistical software package PQSTAT version v.1.6.2. Mineral analysis was done by inductively coupled plasma/mass spectrometry (ICP/MS) after closed vessel microwave digestion steps. The red wines were purchased from commercial suppliers. The PCA analysis of experimental parameters (Fig.1) showed that the first two principal components carry the most important information. Together at each case they explain a great part, as much as above 90%, of the variance. Analysis of correlation matrix gave Chi-square statistic: 29.69 for 6 degrees of freedom with p-value < 0.001. For the first time, a negative linear correlation between the amount of trans-isomer and aluminum and copper was observed. However, accumulation of heavy metals in foods has been described in literature since the early 1970s, but coincidence of both components in wines was noticed for the first time.

Figure 1. Factor loadings graphKeywords: Principal Component Analysis, Correlation Analysis, Resveratrol, Red Wine, Metallic Contaminants

References [1] Flieger Jolanta, Tatarczak-Michalewska Małgorzata, Blicharska Eliza, Anal.Lett. 2016,

http://dx.doi.org/10.1080/00032719.2016.1178756 [2] Flieger Jolanta, Tatarczak-Michalewska Małgorzata, Blicharska Eliza, Świeboda Ryszard, Banach Tomasz,

J. Chrom. Sci. send to the Journal. [3] Ivanova-Petropulos Violeta, Wiltsche Helmar, Stafilov Trajče, Stefova Marina, Motter Herber, Lankmayr

Ernst, Food Chemistry, 2011, 124, 354-361.

28

http://dx.doi.org/10.1080/00032719.2016.1178756



O3.16

Large Eddy Simulation of very Rough Boundary Layer Wind Tunnel Flow

PHAM HA THANH*, JÖRG FRANKEFaculty of Engineering, Vietnamese-German University, Thu Dau Mot City, Vietnam

Email: [email protected] (JF), [email protected] (PHT)

Numerical simulation based investigations of wind related phenomena in urban environments are more and more conducted by Large Eddy Simulation (LES), which makes validation of LES for these applications an important topic. Experimental data from wind tunnel experiments are the most suitable for validation, because of high spatial and temporal resolution and reproducibility. For the physical modeling of atmospheric boundary layer (ABL) flows, a boundary layer wind tunnel (BLWT) is used, which generates a scaled ABL flow with vortex generators and roughness elements in the so called flow development section. The interaction of the scaled ABL flow with a scaled urban model is then investigated in the subsequent test section. In this contribution, the flow in the development section of the Environmental Wind Tunnel Laboratory’s BLWT at the University of Hamburg, Germany, is numerically simulated by LES using the open source solver OpenFOAM 2.4.0. The simulation is primarily performed to generate spatially resolved and time dependent inflow boundary conditions for the LES of flow and dispersion in a generic central European city center model, Michelstadt, which can be validated against a large number of corresponding velocity and concentration measurements. Due to the availability of velocity measurements at several locations in the BLWT without the Michelstadt model, validation of the present simulation is possible and results are presented for mean velocities, root mean square values, Reynolds stresses and spectra. It is shown that the simulation results between the roughness elements compare partly well with the measured data.

Keywords: LES, Boundary Layer Wind Tunnel, Validation, Precursor Simulation, Michelstadt

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O3.17

Using Various RANS Models to Evaluate the Impact of Building Roof Shape on the Airflow and Pollutant Transport in Street Canyon

THANH-CHUYEN NGUYEN*, VAN-THINH NGUYENDepartment of Civil and Environmental Engineering, College of Engineering, Seoul National University, Korea


Air quality management in urban areas requires the use of advanced modeling tools, which are able to predict and evaluate the pollution level under different traffic and meteorological conditions. In this study, various Reynolds-averaged Navier-Stokes (RANS) models have been applied to simulate the airflow and pollutant transport in the lower part of the atmospheric boundary layer developing right above the building roofs. The study is focused on several two-dimensional multiple street canyon configurations corresponding to building’s roof shapes and the aspect ratios in order to evaluate the performance of various turbulence models, such as standard k-, realizable k-, k- and k- SST models. The numerical results are compared with different datasets obtained from the papers of Yassin (2011) and Takano and Moonen (2013), which are covering a wide range of aspect ratios, roof angles, free stream velocities and turbulence Schmidt number. The numerical simulations are agreed reasonably with the observations. In addition, it is also found that the k- model produced a better result in comparison with other two-equation turbulence models in most study cases to simulate the airflow and pollution transport in street canyon.

Keywords: Street canyon, RANS model, roof shape, pollutant dispersion, airflow

References[1] Takano, Y. and Moonen, P., On the influence of roof shape on flow and dispersion in an urban street canyon, Journal of Wind Engineering and Industrial Aerodynamics, 2013, 123, 107-120[2] Yassin, M.F., Impact of height and shape of building roof on air quality in urban street canyons, Atmospheric Environment 2011, 45, 5220-5229.

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O3.18

The Importance of Demand Prediction for Vehicle Relocation Strategy Development in One-Way Car-Sharing System

EUNHAN KA, DONGJOON WOO, CHUNGWON LEE*

Department of Civil and Environmental Engineering, Seoul National University, Seoul, South KoreaEmail: [email protected]

With the advent of sharing economy, various services rapidly appeared in all over the world. Among them, car-sharing service is a representative service in many developed countries as well as many developing countries. Most services are two-way service, under which users should return their car to the station they rented. In these days, because of the inconveniences of the two-way service, one-way service has been introduced. One-way service is convenient for users because there is no need to go back to the pick-up station and to pay during parking as well. However, car-sharing service providers will encounter the vehicle imbalance on their stations, which might lower the system efficiency as one-way rentals increases. Thus, increasing one-way rentals need to solver this issue.To resolve this issue, vehicle relocation strategy is an alternative. This study suggests incorporating demand prediction for this vehicle relocation strategy development. Using the randomly generated data, a relocation strategy with demand prediction is compared with ‘First Request First Service(FRFS)’ strategy. The result conforms that incorporating demand prediction can significantly improve the system performance measured by some indices such as reservation acceptance rate and total vehicle rented time in most of demand scenarios.

Keywords: Car-Sharing, One-Way Service, Vehicle Relocation Strategy, Demand Prediction, Simulation.

References [1] Barth Mattew; Todd Michael, Transportation Research Part C: Emerging Technologies 1999, 7, (4), 237-259[2] Alvina Kek; Ruey Cheu; Miaw Chor, Transportation Research Record: Journal of the Transportation

Research Board 2006, (1986), 81-88 [3] Alvina Kek; Ruey Cheu; Qiang Meng; Chau Ha Fung, Transportation Research Part E: Logistics and

Transportation Review 2009, 45, 1, 149-158[4] Rahul Nair; Elise Miller-Hooks, Transportation Science 2011, 45, 4, 524-540[5] Gonçalo Homem de Almeida Correia; António Pais Antunes, Transportation Research Part E: Logistics and

Transportation Review 2012, 48, 1, 233-247[6] Angela Febbraro; Nicola Sacco; Mahnam Saeednia, Transportation Research Record: Journal of the

Transportation Research Board 2012, 2319, 113-120[7] Diana Jorge; Gonçalo Homem de Almeida Correia, European Journal of Transport and Infrastructure

Research 2013, 13, 3, 201-220[8] Simone Weikl; Klaus Bogenberger, IEEE Intelligent Transportation Systems Magazine 2013, 5, 4, 100-111[9] Wei David Fan, Journal of the Transportation Research Forum 2014, 53, 3, 7-20[10] Diana Jorge; Gonçalo Homem de Almeida Correia; Cynthia Barnhart, IEEE Transactions on Intelligent

Transportation Systems 2014, 15, 4, 1667-1675[11] Mehdi Nourinejad; Matthew J. Roorda, Transportation 2015, 42, 3, 497-518

31



O3.19

Drivers Evaluation Indices Considering the Interaction with Surrounding Vehicles on Driving Simulator

JOONEUI HONG , SANGHYEOP LEE, CHUNGWON LEE*


Driving education on roads is not easy to be implemented for the safety issue on participants. Driving Simulator (DS) is a viable alternative. Although DS has been widely used, driver evaluation criteria are not well established according to our literature review. This study suggests a new evaluation indices based on the interaction between the subject and surrounding vehicles.As target indices, we have chosen Modified time to collision (MTTC), Deceleration Rate to avoid the Crash (DRAC), Proportion of stopping distance (PSD), Deceleration Rate (DR). MTTC means time to collision considering the velocity and deceleration of both leading vehicle and following vehicle, which can capture the magnitude of danger when driver follows the leading vehicle. DRAC means how deceleration should be done to avoid crash. By DRAC, we can check the magnitude of danger like MTTC but with respect to deceleration. PSD is the ratio between remaining distance and minimum stopping distance. When the value is smaller than 1, the collision cannot be avoided. We can check how the driver maintain safety distance in collision risk situation. The last index is DR. DR means how driver reacts first when there is a risk of collision.To apply these indices in analyzing the driving behavior, how to calculate the index value from DS data need to be resolved. Simply, averaging can be tested. The number of exceeding the predefined critical values can be used. The cumulative amount of exceeding the predefined critical values can be used as well. This study also suggests where the indices should be applied on specific road facilities, rather than a whole road of each scenario. Collecting DS data and investing the properness of each index remains as a future research.

Keywords: Safety, Driving Simulator, Evaluation Criteria, Surrounding Vehicle, Road Facility.

References [1] Gettman, Douglas ; Larry Head, Transportation Research Record: Journal of the Transportation Research

Board 1840, 2003, 104-115.[2] De Winter, J. C. F. et al., Proceedings of the 25th European Conference on human decision making and

manual control (EAM)(Valenciennes, France). 2006.[3] van Driel, C. J. G.; Hoedemaeker M.; van Arem B., Transportation Research Part F: Traffic Psychology and

Behaviour 10, no. 2 (3// 2007): 139-52[4] Ozbay, Kaan, et al., Transportation Research Record: Journal of the Transportation Research Board 2083, 2008, 105-113. [5] Niezgoda, M.; Kamiński, T.; Kruszewski, M., Journal of KONES, 2012, vol. 19, no.4, 503-511[6] M Subramaniyam; SJ Park; HK Lim; DG KimJounal of Ergonomics Society of Korea, 2013, 200-204.

32



O3.20

A Comparison of Car-Following Model Parameters between Normal and Raining Conditions

SUNHO KIM , YEONGBEOM KWON, CHUNGWON LEE*


Traffic flow has been investigated through diverse models. Among them, the car-following model has been widely used to identify the stability characteristics of traffic flow. Different drivers may have dissimilar driving behavior, result in different parameters in the model. In the real world, a driver’s behavior can be changed by external factors including snow, fog, rain, etc. There happens a remarkable distinction based on a complex element such as visual situation and/or condition of the road. This study focuses on the impact of rain on driving behavior by estimating and comparing car-following model parameters. The car-following experiments on both normal and rainy days have been examined with a test-car, equipped a radar and video recording function. The test car can measure the front and rear vehicle movement as well as own movement. Using the collected data from the experiment, the parameters of GM’s Models have been estimated separately between normal and rainy days. The preliminary data analysis clearly shows that raining impacts on parameter values. More wide range are observed in rainy data. This means that some drivers might be more careful in rainy days but some drivers are not. These findings can be carried out for implementing surrounding vehicle motion on a realistic driving simulator in different weather conditions. More data collection and different model application will be performed in near future.

Keywords: “Car-Following”, “GM Model”, “Traffic flow”, “Parameter”, “Calibration”

References [1] Mark Brackstone; Mike McDonald, Transportation Research Part F: Traffic Psychology and Behavior 1999,

v2, 181-196[2] Tao Ma; Baher Abdulhai, Transportation Research Record: Journal of the Transportation Research Board

2002, 1800, 6-15 [3] Gemunu Gurusinghe; Takashi Nakatsuji; Yoichi Azuta; Prakash Ranjitkar; Yordphol Tanaboriboon,

Transportation Research Record: Journal of the Transportation Research Board 2002, 1802, 149-158[4] Mithilesh Jha; Ganesh Gopalan; Adam Garms; Bhanu Mahanti; Tomer Toledo; Moshe Ben-Akiva,

Transportation Research Record: Journal of the Transportation Research Board 2004, 1876, 121-131[5] Seung-Jun Kim; Wonho Kim; L. Rilett, Transportation Research Record: Journal of the Transportation

Research Board 2005, 1935, 111-119[6] Ramachandran Balakrishna; Constantinos Antoniou; Moshe Ben-Akiva; Haris Koutsopoulos; Yang Wen,

Transportation Research Record: Journal of the Transportation Research Board 2007, 1999, 113-120[7] Jung-Beom Lee; Kaan Ozbay, Transportation Research Board’s 87th Annual Meeting 2008, 08-2964[8] Winnie Daamen; Christine Buisson; Serge P. Hoogendoorn, In Traffic Simulation and Data:Validation

Methods and Applications; Winnie Daamen; Christine Buisson; Serge P. Hoogendoorn, Ed.;CRC Press, London&NewYork, 2014; Vol.1CRC Press 2014; Vol. 1, Chapter 4, pp89-118

33



POSTERS

P3.1

A Proof for a Posteriori Error Lower Bound When Solving Laplace-Beltrami Equation on Spheres

TUNG LE*, DUONG T. PHAMComputational Engineering Program, Vietnamese-German University, Binh Duong, Vietnam


We present a proof for a posteriori lower bound for the error estimates when solving Laplace-Beltrami equation on the sphere using spherical splines. Bubble functions, defined by using Bernstein polynomial, are required in the proof. A local indicator based on a posteriori error estimates is used to design a mesh-refinement scheme to reduce the computational cost. The theoretical results are corroborated by numerical experiments.

Keywords: Bernstein polynomial, bubble function, Laplace--Beltrami equation, sphere, finite element methods, a posteriori error estimate, adaptivity

References[1] Pham, Duong; Le, Tung. A Posteriori Error Estimation for Laplace-Beltrami Equation on Spheres with

Spherical Splines. CAMWA, submitted.

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P3.2

A Computation of Stiffness Matrix When Solving Weakyly-Singular Equation on Spheres

TUNG LE* , DUONG T. PHAMComputational Engineering Program, Vietnamese-German University, Binh Duong, Vietnam


We suggest a new computation of stiffness matrix arising when solving weakly-singular equation on the unit sphere with spherical splines. The singularity in the integrals is removed by using rotational techniques with piecewise homogeneous polynomials. A significant reduction in computational cost is illustrated by numerical experiments.

Keywords: Bernstein polynomial, weakly-singular equation, hyper-singular equation, sphere, finite element methods, spherical splines.

References[1] Pham, T. D.; Tran, T.; Chernov, A. Pseudodfferential Equations on the Sphere with Spherical Splines. Math.

Models Methods Appl. Sci. 21 (2011), no. 9, 1933-1959, 65N30 (35S15 41A15)[2] Pham, T. D; Tran, T., A Domain Decomposition Method for Solving the Hypersingular Integral Equation on

The Sphere with Spherical Splines. Numer. Math. 120 (2012), no. 1, 117-151, 65R20 (45E05)

35



P3.3

Sliding Mode Tracking Control Using Radial Basis Function Neural Networks

TRAN QUANG THUANDepartment of Electronic Engineering, Posts and Telecommunications Institute of Technology, HCM city,

VietnamEmail: [email protected]

This paper considers the problem in sliding mode tracking control of nonlinear dynamical system using radial basis function neural networks. Here, we present the simulation results of sliding mode control (SMC) and identification approaches for nonlinear system using radial basis function (RBF) neural networks [6]. We discuss the application of the nonlinear system identification on designing the sliding mode tracking control law for a couple of double pendulum systems.

Keywords: Sliding Mode Control, Tracking Control, Radial Basis Function, Neural Network, Nonlinear Dynamical System.

References[1] Jeffrey T.Spooner and M. Passino, “Decentralized Adaptive Control of Nonlinear Systems Using Radial

Basis Neural Networks”, IEEE Transactions on Automatic Control, 1999, vol.44, No.11, pp.2050-2057.[2] M.Önder Efe, Okayay Kaynak, Xinghuo Yu, Bogdan M.Wilamowski, “Sliding Mode Control of Nonlinear

Systems Using Gaussian Radial Basis Function Neural Networks”, IEEE Transactions on Neural Networks, 2001, pp.474-479.

[3] Hui Peng, Tohru Ozaki, “A Parameter Optimization Methode for Radial Basis Function Type Models”, IEEE Transactions on Neural Networks, 2003, Vol.14, No.2, pp.432-438.

[4] Chu Kiong Loo, Mandava Rajeswari, M.V.C Rao, “Novel Direct and Self – Regulating Approaches to Determine Optimum Growing Multi-Expert Network Structure”, IEEE Transactions on Neural Networks, 2004, Vol.15, No.6, pp.1378-1395.

[5] M.Önder Efe, “Variable Structure Systems Theory in Training of Radial Basis Function Neurocontrollers – Part II: Applications”, NIMIA-SC2001 – 2001 NATO Advanced Study Institude on Neural Networks for Instrumentation, Measurement, and Related Industrial Applications: Study Cases Crema, Italy, 9-20 October 2001.

[6] Dong Si Thien Chau and Duong Hoai Nghia, “Nonlinear System Identification Using Radial Basis Neural Networks”, in Proc. International Symposium on Electrical & Electronics Engineering 2005 – HCM City, Vietnam.

[7] Emelyanov, S.V. “Variable structure control sytems”, Moscow, Nauka, 1967.[8] H. Khalil, “Nonlinear Systems”, 2002.

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P3.4

Rainfall-Storage-Pump-Discharge (RSPD) Model for Sustainable and Resilient Flood Mitigation

DUC CANH NGUYEN*, MOO YOUNG HANDepartment of Civil & Environmental Engineering #35-518, College of Engineering, Seoul National University,

South KoreaEmail: [email protected]

Urban flooding is becoming an increasingly important issue in the 21st century, due to climate change and urbanization. This paper proposes micro-catchment rainwater management with control measures. It also develops the Rainfall-Storage-Pump-Discharge (RSPD) model as a resilient and sustainable flood mitigation approach, given the uncertainty caused by climate change. In this study, the rainwater tank system for runoff management was designed using the RSPD model, which involves controlled pumping to manage heavier rainfall runoff. The present urban flood problem can be mitigated by engineered RSD (Rainfall-Storage-Discharge) or, even better, by controlled pumping using the RSPD system, without resorting to the expensive option of increasing the capacity of existing tanks and storm sewerage. The minimum retention volume or the appropriate arrangement of the tank with the pumping system to control the peak runoff from the rooftop can be easily determined from the Tank volume-Design period-Pumping rate curves. The minimum tank capacity required to reduce the peak runoff flow from a 100-year rainfall event to a 2-year rainfall event, without usage, is 11 m3/100 m2. The tank capacity can be also reduced to 9, 7, 6, 5, and 4 m3/100 m2, with pumping rates of 25, 50, 75, 100, and 125 L/min, respectively. Moreover, the overcharging pumping capacity for a particular tank volume can be determined from the curves. The pumping rate at constant peak flow rate should be omitted from the design combinations, as it could lead to overcharging.

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