ISSN: 1998-0159



Year 2008

All papers of the journal were peer reviewed by two independent reviewers. Acceptance was granted when both reviewers' recommendations were positive.

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    Paper Title, Authors, Abstract (Issue 1, Volume 2, 2008)


Explicit 2D Matrix Free Galerkin Finite Volume Solution of Plane Strain Structural Problems on Triangular Meshes
S.R. Sabbagh-Yazdi, N.E. Mastorakis, M. Esmaili

Abstract: In this paper, a novel matrix free Finite Volume Method based on Galerkin Approach is introduced for solution of weak form of two dimensional Cauchy equilibrium equations of plane strain solid state problems on linear triangular element meshes. The developed shape function free Galerkin Finite Volume structural solver explicitly computes stresses and displacements in Cartezian coordinate directions for the two dimensional solid mechanic problems under either static or dynamic loads. The accuracy of the introduced algorithm is demonstrated by comparison of computed results of two cantilever beams under static concentrated and uniformly distributed loads with analytical solutions. The performance of the solver is presented in terms of convergence behavior of the method. In order to present the applicability of the introduced method to solve dynamic problems, the computed displacements of a storage tank frame under oscillating hydrodynamic load is compared with the reported data in the literature.


Two Tiers Ontology Alignment
A. Hongzhe Liu, B. Hong Bao, C. Junkang Feng

Abstract: It is desirable to the distribute data and knowledge of a huge amount of cultural heritage and to make them available readily to people, but the distributed, heterogeneous and autonomous nature of the databases of digital museums gives rise to the challenge of achieving the best retrieval results in cross-system searching. To make this difficult task tractable, we analyze semantic heterogeneities among these data sources and describe an two tier (concept and instance) approach to accomplish ontology alignment by using the information flow theory.


3D vertex-base unstructured finite volume model with bi-harmonic dissipation for turbulent wind flow around a group of cooling towers
S.R. Sabbagh-Yazdi, N.E. Mastorakis, and M. Torbati

Abstract: In this paper, a three dimensional turbulent air flow solver is introduced and its accuracy for the solution incompressible flow equations in conservative form. The equation of continuity is simultaneously solved with the three equations of motion in a coupled manner by application of the pseudo compressibility technique for the steady state problems. The set of flow equations in Cartezian coordinate system is combined with a SGS (Sub-Grid Scale) eddy viscosity turbulence model. The discrete form of the three-dimensional flow equations are formulated using the vertexbase overlapping Finite Volume Method for unstructured mesh of tetrahedral cells. In order to damp out the numerical oscillations during the explicit solution procedure, a formulation for bi-harmonic artificial dissipation is used which suits the unstructured meshes of tetrahedral cells. Using unstructured meshes provides the merit of accurate geometrical modeling of the curved boundaries of the cooling towers. In order to demonstrate the performance of the developed model, the velocity and pressure fields due to wind flow around a group of three cooling towers with arbitrary arrangements, is presented. The computed results are presented in terms of color coded maps of pressure and velocity fields as well as velocity vectors on boundary surfaces of the solution domain.


Two Random Interfaces of Statistical Mechanics Models
J. Wang, and B. T. Wang

Abstract: We consider the limiting statistical properties of fluctuations of statistical mechanics models. The two random interfaces of one-dimensional statistical physics models is modeled and investigated in the present paper. The two random interfaces are constructed by assuming that there is a specified value of the large area in the intermediate region of the two random interfaces, and the two random interfaces have fixed endpoints. When the inverse temperature is large enough, we show that the limiting distributions of the two random interfaces of the model convergence to a Gaussian distribution.


The Statistical Properties of Fluctuations of Interfaces for Voter Model Models
J. Wang, and Q. Y. Wang

Abstract: We consider the limiting statistical properties of fluctuations of the voter model. The voter model is one of interacting particle systems, and it is a continuous Markov process on the lattice. Applying the theory of the voter model, an interface model defined from the voter model is defined and studied in the present paper. The interface model is analyzed and estimated by the voter model and the theory of stochastic analysis, including the stopping time method. Further, we show that the probability distributions of the fluctuations, under some conditions, converge to the corresponding distribution of a geometric Brownian motion.


Risk Specifications in Risk Efficiency Analysis
Cenktan Ozyildirim, Begumhan Ozdincer

Abstract: Recent efficiency models are based on the fact that the isk preferences are important factors affecting the profitability of a bank. The risk specifications in these models are generally based on a single parameter, such as market risk or standard deviation of predicted profit. This study, arguing that a single parameter will not be sufficient to specify the structure of different types of risks, aims to develop a multiparameter risk efficiency frontier. It is discussed that capital adequacy ratio formulations have some weaknesses that make them inferior risk parameters. It is also shown that different risk types may have differing effects on profitability. Since the amount of risk of different types assumed by a bank is also a part of its production plan, we argue that a multiparameter risk specification should be employed to have a complete efficiency frontier analysis.


The 2-Dimensional Probabilistic Bin Packing Problem : An average case analysis
Leila Horchani,and Monia Bellalouna

Abstract: In the probabilistic two-dimensional Bin Packing problem (2D-PBPP), one is asked to pack a random number of rectangular items, without overlap and any rotation, into the minimum number of identical square bins. In this paper we consider the re-optimization procedure used for solving probabilistic combinatorial optimization problems and an approximation of this strategy: the redistribution strategy according to an heuristic. According to computational results we show that the redistribution strategy according to some efficient heuristics generates results near those given by the re-optimization strategy which is impossible to be carried out.


Algebraic construction of exact difference equations from symmetry of functions
Toshiaki Itoh

Abstract: Difference equations or exact numerical integration scheme, which have general solutions, are treated algebraically. Eliminating the symmetry in mixed functions, we can construct numerical integration schemes correspond to some ordinary differential equations that have same mixed functions. When arbitrary functions are given, whether we can construct numerical integration schemes that have solution functions equal to given function or not are treated.


Linear Time-Varying Systems: Model Parameters Characterization Using Intervals Analysis
Kyarash Shahriari, Stanislaw Tarasiewicz

Abstract: A strategy is proposed to model the complex industrial systems using linear time-varying system (LTV S). The proposed methodology is independent of model structure and the model may take any classic linear structure such as finite impulse response, inputoutput relation structures etc. To take into account the error between system and model due to model order reduction, variation of system behavior in time and perturbations, model?s parameters are considered varying but bounded variables characterized by intervals. The output of this model is characterized by a function of the piecewise linear parameters which contains all possible system?s responses taking into account modeling error as well as the perturbations.




Effective risk mitigation: a user prospective
Basit Shahzad, Sara Afzal Safvi

Abstract: Much effort has been put in order to identify the possible risks hindering the successful completion of software projects. Techniques in risk mitigation, management and monitoring plan devise the estimation process of risk likelihood and their possible impact on the progress of software project. Risk Mitigation, Monitoring, Management is a thorough and continuous process, which aims to bring the potentially losing project to the safer shore. Hence every phase of this plan is of equal importance. Generally more focus is maintained in the initial phases i.e. the identification and assessment of possible risks. Whereas formalizing a concrete avoidance / mitigation plan must also be devised, to ensure that risk do not mature in problem. A response should be ready in advance. Generally it is easier to identify and assess the risk but to suggest suitable mitigation / contingency plan is far more difficult task. The measurement of effectiveness of these mitigation / contingency plans should be well carried. It must ensure that after the execution of such plans the risk exposure is reduced or preferably eliminated. This can be referred as the feasibility of the mitigation / contingency plan, which is critically analyzed and measured for its effectiveness. This paper focuses on the prioritization and then handling and proposing the mitigation strategy for each risk factor. It is strongly believed that just proposing the mitigation strategy is not sufficient. Although all the mitigation strategies proposed in the paper are the outcomes of the views of experienced people having both: the vision and intuition yet it was necessary to observe the acceptability of such mitigation strategies among the people and the organizations who are affected from such risk arrivals. In order to justify the need a survey was conducted among fifty representative people from different domains among students, academicians and professionals. The risk factor at question and the proposed mitigation strategy were put before the respondents and they were required to support the possible strategy that they believed suitable for that specific risk factor. This practice was repeated for all risk factors. It was also decided that one individual would support only one mitigation strategy for one risk.


An Approach to Enhance Dynamic Matrix Control Performance
Oscar Camacho, Edinzo Iglesias, Lu? Valverde, Francklin Rivas

Abstract: This paper shows a set of tuning equations, based on the sliding surface response to forecast changes in the parameters of the process, which are used to enhance and to tune the predictive dynamic matrix controller parameters. The controller presents a fixed algorithm and its tuning parameter equations were developed relating the characteristics values of the sliding surface and the characteristic parameters of the first order plus deadtime model. Simulations on a blended tank with variable level that presents non linear behavior are considered.


Multi-loop PI Controller Design for Enhanced Disturbance Rejection in Multi-delay Processes
Truong Nguyen Luan Vu and Moonyong Lee

Abstract: In this paper, a new design method is proposed for multi-loop PI controllers in the multiple input, multiple output (MIMO) systems in two cases: set-point tracking and disturbance rejection. The generalized IMC-PID approach [1], which is extended from single input, single output (SISO) systems to MIMO systems, is considered to identify the tuning parameters of multi-loop PI controllers. However, there is not enough robustness in multi-delay systems which contain a lot of noise and disturbance. The proposed design method can solve this problem by using the magnitude of sensitivity (Ms) theory. A simulation study is performed for the well-known process model and the response performances compared favorably with some famous tuning methods. The results show that the proposed method is superior to existing techniques for multi-delay processes.


yourMathsCorner: A blog-based approach to learning prerequisite mathematical knowledge at the tertiary level
Fariel Mohan

Abstract: Over the decades, the imparting of knowledge by teachers has always proven to be challenging. Research in teaching is playing a key role in coming up with more effective approaches to imparting knowledge to students. In the past decades, research in education has proposed various approaches to enhance the teaching / learning process, such as a social constructivist approach, a cognitive approach, a community approach, and a project-based approach. In the Caribbean, the traditional teaching approach to imparting knowledge, i.e., chalk and talk, continues to be used. This paper examines the challenges faced with the teaching of 1st year Mathematics students at the diploma level in a tertiary institution in the Caribbean. A cost effective approach is used to illustrate the teaching of mathematics to 1st year students. In the first phase of this project, the need to teach pre-requisite Mathematics to 1st year diploma students is addressed. The paper highlights the benefits of collaborative learning which stimulates students to think. A virtual classroom provides the opportunity for a student to explain to others thus performing the role of a teacher. This enhances the student's skill of communicating his ideas. An additional benefit of the virtual classroom is that a student is not restricted to learning only at the scheduled classroom hours. The success of the first phase of the project was highlighted by improved student academic success and better self-esteem.


A study on optimum calculation of the total transmission ratio of four-step helical gearboxes with first and third step double gear-sets
Vu Ngoc Pi

Abstract: This paper presents a new study on the applications of optimization and regression analysis techniques for optimum determination of the partial transmission ratios of four-step helical gearboxes with first and third step double gear-sets. The objectives of the calculations are minimum mass of gears and minimum gearbox cross section dimension. Based on the moment equilibrium condition of a mechanic system including gear units and their regular resistance condition, optimization programs for predicting the partial ratios of the gearboxes is conducted. Regression analyses were carried out based on the results of the optimization programs and explicit models for the determinations of the partial ratios are proposed. Using these models, the calculation of the partial ratios is accurate and simple.


Portfolio simulation with social bookmarking in higher education
Eric Zhi Feng Liu and Yu Fang Chang

Abstract: This study examined the feasibility of the integration of social bookmarking and portfolios through a case study on an introduction to an instructional media course at a research university in Taiwan. The instructional aims of this case study emphasize the use of information technology in learning; the collection, selection, evaluation, and sharing of information; discussions with peers; learning from peer feedback; construction of learning communities; and knowledge construction. In this case study, a questionnaire was used to evaluate students? perceptions towards the learning activities. Statistical analyses confirmed that students were satisfied with this course and had high self-efficacy while using the social bookmarking application. Students collected a total of 4962 web pages, and the first three tags that the students used in the top 10 web pages were news, education, and health.


Impact of New Sub-Classes of Hypercube Topology on Execution Time of Matrix Multiplication
M. Amiripour and H. Abachi

Abstract: Today?s advanced research areas such as DNA computing, different branches of nanotechnology, immune cell system and optical computing require extensive data processing. Therefore, parallel processing systems with sophisticated hardware and software platforms are widely used. Furthermore, implementing the right algorithm which affects the overall execution time is a challenging task. This paper presents the principle of a massively parallel processing system based on Master-Slave Super-Super Hypercube 4-Cube (MS3H4-Cube) topology which could be easily implemented by using SGI products. Moreover, it is verified that the execution time of a matrix product is shorter when is applied on Master- Slave Super-Hypercube (MSSHP) compared with Hypercube (HP) topology.


    Paper Title, Authors, Abstract (Issue 2, Volume 2, 2008)


Tools and Techniques for Supporting Reverse Logistics Optimization: Methodology, Case Study and Project Proposal
P. Giribone, R. Revetria, M. Schenone, F. Oliva, E. Nikolaeva Nikolova, G. Chavdarova Peneva

Abstract: The following research documentation focuses on building a network for reverse logistics of products that are taken back for disassembly and retrieval of reusable components for remanufacturing. The goal is to achieve optimization between the costs and the clustering. The paper outline also an innovative approach designed to support the establishment of a new socio-economical vision able to reduce products manprint


3 modeling strategies for computing aerated skimming flow parameters over stepped chutes using depth averaged flow solver
S.R. Sabbagh-Yazdi, N.E. Mastorakis, and R. Safaieh

Abstract: In this paper the flow regimes occurring on stepped chutes are reviewed. Then the numerical analysis of skimming flow using a set of depth averaged equations in inclined coordinate system is described. The numerical computations of air entrainment in the skimming flow over stepped spillways are performed using three modeling strategies. In the first modeling strategy, the water flow equations are converted to discrete form using the overlapping cell vertex finite volume method on triangular unstructured mesh, and then, the air concentration distribution is computed using the final solution of flow parameters. In the second modeling strategy, the mean air concentration profiles are computed at every time step of the numerical solution of water flow equations and its effects on reduction of bed friction and flow depth bulking are considered in formation of flow field. In the third modeling strategy, in addition to the second modeling strategy, the effects of changes in air-water mixture on density changes and its effect on flow motion are considered. The computed results of air entrainment into the supercritical skimming flow on stepped spillways are compared with laboratory experimental measurements.


Modeling of Solidification Conditions and Melt Treatment on Microporosity Formation
K.Davami, M.K.Besharati, M.Shaygan

Abstract: Cast Aluminum-Silicon alloys are used in automotive and industrial weight sensitive applications because of their low density and excellent castability. The presence of trapped gas and or shrinkage pores in certain locations within casting has been shown to influence mechanical properties such as tensile strength and fatigue life. These micromechanical defects can be found most anywhere in casting depending on processing conditions. A large amount of porosity located in the center of the casting may have no effect on mechanical properties or fatigue performance. A smaller, isolated pore near a surface may have significant impact on mechanical properties. Hence , it is important to develop a comprehensive model to predict size, location and distribution of microporosity in casting. In this work, we model the effect of various casting process parameters on microporosity formation for equiaxed aluminum A356 alloy casting. The process parameters Include cooling rate, grain refiner and eutectic modifier melt additions. The comparisons between experimental results and simulations demonstrate good agreement.


An investigation of temperature effect on microstructure and mechanical properties of aluminum (A360) processed by thixoforging
M.K.Besharati, K.Davami, M.Shaygan

Abstract: Thixoforging has some advantages over conventional forming processes such as die casting, squeeze casting, and hot/cold forging. Thixoforging can produce non-dendritic alloys for the semisolid forming of complex-shaped parts in metal alloys. Since thixoforging takes place between liquidus and solidus temperature and liquid phase and solid phase exist at the same time, heating circumstances is more significant. In order to achieve homogenous microstructure during heating , eutectic must transformed to liquid completely to gain suitable mechanical properties. The solid phase percentage during forming process in semi-solid condition ,has a very important effect which is affected by heating temperature . In this research, the effect of temperature on thixoforging process and mechanical properties of the work piece was investigated. The lap, which is an external defect, was observed at higher initial work piece temperature. In hardness test, it was observed that the hardness decreased at higher initial work piece temperature.


Fingerprint Classification Using Singularities Detection
Liu Wei

Abstract: Applying the Automatic Fingerprint Classification technology, the search of a fingerprint can be restricted to a limited scope while performing fingerprint identification, so that the retrieval effectiveness of the whole system can be improved greatly. Singularities are the most important and reliable features in classification. This paper describes an improved rapid singularity searching algorithm which employees delta field Poincare index and a rapid classification algorithm to classify the fingerprints into 5 classes. The detection algorithm only searches the direction field which has the larger direction changes to get the singularities. Then a singularities detection post-processing method is used to increase the accuracy. The classification algorithm uses the delta direction and the singularities to partition the similar classes. The algorithms were tested on NIST-4 database and got a good performance.


Using modular neural networks to model self-consciousness and selfrepresentation for artificial entities
Milton Mart?ez Luaces , Celina Gayoso, Juan Pazos Sierra and Alfonso Rodr?uez-Pat?

Abstract: Self-consciousness implies not only self or group recognition, but also real knowledge of one?s own identity. Self-consciousness is only possible if an individual is intelligent enough to formulate an abstract self-representation. Moreover, it necessarily entails the capability of referencing and using this selfrepresentation in connection with other cognitive features, such as inference, and the anticipation of the consequences of both one?s own and other individuals? acts. In this paper, a cognitive architecture for selfconsciousness is proposed. This cognitive architecture includes several modules: abstraction, self-representation, other individuals' representation, decision and action modules. It includes a learning process of self-representation by direct (self-experience based) and observational learning (based on the observation of other individuals). For model implementation a new approach is taken using Modular Artificial Neural Networks (MANN). For model testing, a virtual environment has been implemented. This virtual environment can be described as a holonic system or holarchy, meaning that it is composed of autonomous entities that behave both as a whole and as part of a greater whole. The system is composed of a certain number of holons interacting. These holons are equipped with cognitive features, such as sensory perception, and a simplified model of personality and self-representation. We explain holons? cognitive architecture that enables dynamic selfrepresentation. We analyse the effect of holon interaction, focusing on the evolution of the holon?s abstract self-representation. Finally, the results are explained and analysed and conclusions drawn.


Optimum Shape in Brick Masonry Arches Under Static And Dynamic Loads
Kaveh Kumarci, Arash Ziaie, Mehran Koohikamali, Arash Kyioumarsi

Abstract: The objective of this study is to determine brick masonry arches under dynamic and static loads. In this paper, considerable attention is given to arches, their importance, modeling stages, dynamic analysis, static analysis and arch optimization using ANSYS11 software. A multiple stage analysis framework was conducted for semicircular arch: 1- The study of optimum shape for semicircular arch on the base of minimize of arch weight. 2- Determination of linear and nonlinear analysis limits by increase of density. 3- The study of optimum shape in semicircular arch by linear and nonlinear analysis. All of these stages have been conducted for obtuse angel arches, four- centered pointed arch, tudor arch, ogee arch, equilateral arch, catenary arch, lancet arch, four-centered arch (normal, diminished and steep). The main purpose has been study of arch optimum shape for minimize of weight: Finally, according to the results, the optimum shape in arches under dynamic load has been determined.


Using neural network in plate frequency calculation
Arash Ziaie, Issa Mahmoudi, Arash Kyioumarsi

Abstract: The general goal of this research is the determination natural regular frequency of a plate by artificial neural network with various supporting conditions. For the subject of neural network, training or learning algorithms are applied the most famous of which is back propagation algorithm.This algorithm is a systematic method for training multi layer artificial neural network. Back propagation algorithm is based on gradient descant which means that it moves downward on the error declination and regulates the weights for the minimum error. In this research, the real frequency is calculated first using ANSYS program and is defined as a goal function for neural network, so that all outputs of the network can be compared to this function and the error can be calculated. Then, a set of inputs including dimensions or specifications of plate are made using MATLAB program. After the determination of algorithm and quantification of the network, the phases of training and testing of the results are carried out and the output of the network is created. It is concluded that according to results, the performance of the neural network is optimum, and the errors are less than 7%, so the network can perform training in different manner. Furthermore the time of frequency calculations in neural network is less than real analysis time that calculated by ANSYS software, and it?s precision is acceptable(less than 10%).


Two dimensional dynamic modeling of a coaxial plasma opening switch with effect of Hall current and RLC equation
M.T. Mehrabani, A. Abbassi, M. M. Attaran

Abstract: The plasma dynamic and the magnetic-field penetration in a coaxial plasma opening switch (POS) have been studied based on the two dimensional single-fluid magneto hydrodynamic (MHD) equation coupled with generalized Ohms law. MHD equations were discretized using Roe averaging method which is in essence a non-diffusive scheme. RLC equation is solved using Runge Kutta method to determine the current of the generator during the conduction phase. For this purpose, the voltage of the generator edge of the plasma has been obtained by integrating the electric field on the edge by Simpson method. The code was validated in two cases: firstly, assuming the boundary of magnetic field changes sinusoidal and secondly, obtaining magnetic field using calculated current from RLC equation. The contours of magnetic field, plasma density and plasma temperature are plotted in various time with initial plasma density n0=8?1015 cm-3.


Simulation Based Design for a Railway Logistics Re-Engineering Project
Claudia Caballini, Pier Paolo Puliafito, Roberto Revetria, Flavio Tonelli

Abstract: In the last decades globalization dynamics have determined a continuous increase in freight flows and a growing global competition for the interception of these flows. This had a tremendous impact on the global supply chains configuration especially on ports, which must be able to handle an increasingly quantity of goods and to quickly ship them towards the consumer and production markets. In order to be able to do that, ports needs more and more space and, at the same time, they require an efficient organizational model for effectively manage so a big quantity of cargo. However many ports, being embedded in the city fabric, can?t easily enlarge their borders for gaining new space and therefore they are obliged to look for new areas in the hinterland. These inner areas represents an extension of the ports borders and they are managed just as they were part of the maritime domain: for this reason they are called ?dry ports?. For an effective working of the ?port-dry port? system, it is fundamental, among other things, that the related transportation infrastructures are suitable and functional to sustain the current and forecast freight flows. This paper regards the analysis of the railway system that joints Genoa port principal container terminals with an hypothetical dry port set in Alessandria, 90 km far from Genoa, with the objective of studying the possible infrastructural criticalities and suggesting proper solutions. To this aim, a simulation model has been developed and tested. The paper proposes the Discrete Event Simulation utilizing Arena software supported by MySQL Data Base Management System. Experimental design techniques (DOE) and neural networks have been utilized as an effective tool to produce an adequate experimental campaign and to study the response surface obtained.


Real-time estimation of peroxides and acidity level of extra-virgin olive oil: an integrated approach
Claudia Caballini, Pier Paolo Puliafito, Roberto Revetria, Flavio Tonelli

Abstract: This work provides a combined method, based on Artificial Neural Networks (ANNs) and Machine Vision (MV) systems, with the aim of assess a real-time estimation of acidity level and of peroxides number of olive oil extracted by a continuous extraction process. These parameters may be accurately measured by means of a chemical analysis (CEE Rule no. 2568/91, G.U. CEE no. L 248, 1991). This analysis has to be performed in an equipped laboratory and does not permit to the operators (working in the oil mill) to have a real-time control of the quality of the extracted oil. The present work allows a straightforward approach for an accurate estimation of the qualitative parameters directly during the oil extraction process, thus allowing a quality control of the oil quality without the requirement of a time-expensive chemical analysis. The estimation is achieved both through the measurement of several agronomical and technological parameters commonly measured by the technicians working at the oil mills and by means of machine vision systems. Some of the parameters correlated to the sanitary condition of olives and to ripeness are evaluated by means of image processing algorithms. An ANN based algorithm is able to process the agronomical, technological and image data and gives, as output, a reliable estimation of peroxides and acidity. The results of the estimation achieved by the ANN based system have been compared with the results of the chemical analyses carried out by Florence Commerce Chamber ?Laboratorio Chimico Merceologico?Azienda Speciale CCIAA di Firenze? according in force to European Union Rules standards. The system has been developed and tested on the oil mill ?TEM Toscana Enologica Mori? of Florence, Italy where is actually running. The work has been financed by the Tuscany Regional Agricultural Development and Innovation Office (ARSIA: Azienda Regionale per lo Sviluppo e l?Innovazione dell?Agricoltura) and is a part of a 3-year project whose objective is to create an entirely software + hardware controlled oil mill.


A Model of Hippocampal Learning with Neuronal Turnover in Dentate Gyrus
Yuko Wakagi and Motonobu Hattori

Abstract: Recent studies have revealed that neurons are replaced in the dentate gyrus of the adult hippocampus. Although it is believed that the hippocampus is essential to store some kinds of memory, the role of neuronal turnover in the hippocampus have not been understood yet. In this paper, we examine the effect of neuronal turnover by using a hippocampal model. Computer simulation results show that the similarity of patterns to be stored is reduced by neuronal turnover, and this contributes to storing similar patterns easily and increasing the storage capacity. Moreover, we show that the number of learning epochs required to store all patterns can be reduced as the neuronal turnover rate becomes large.


Numerical Approximation of Elliptic Partial Differential Equations on soil-tool interaction problems using advanced nonlinear finite element approach
R. Jafari

Abstract: The aim of this paper is to investigate finite element methods for the solution of the Sokolovski elliptic partial differential equation. The problem of solving such equations without triangulating surfaces is of increasing importance in various applications, and their discretization has recently been investigated in the framework of finite difference methods. For the two most frequently used implicit representations of surfaces, namely level set methods and phase-field methods, we discuss the construction of finite element schemes, the solution of the arising discretized problems, and provide error estimates. The variation of reacting force was plot under different solution methods and different input data. Results showed that the level set method outputs have less error than the phase- field method. Also the soil cohesion and mesh density have significant effect on the soil cutting forces.


    Paper Title, Authors, Abstract (Issue 3, Volume 2, 2008)


Effect of blast wave on chosen structure - numerical and experimental study
J. Malachowski

Abstract: This paper is based on non-linear finite element analysis of the effects of the blast wave on structures, caused by the detonation of explosive materials. Dynamic response of a pipeline subjected to the shock wave produced by the detonation of high explosive materials is presented in this paper. Coupled Euler and Lagrange formulation are used in the finite element analysis of such problems to accurately represent the detonation phenomenon. Preliminary results allow for detailed analysis of the blast wave propagation and its influence on the pipeline.


Modeling of Solid-State Circuit Breakers using MATLAB’s Power System Blockset
T. Kulworawanichpong

Abstract: This paper contains a brief of model building for solid-state breakers (SSB) in electric power distribution systems by using GUI-based (graphic user interface) feature of MATLAB/SIMULINK. Utilization of MATLAB software simplifies problem solving complexity and also reduces working time. In this paper, a 22-kV power distribution feeder with a load having the SSB for protection was situated. The proposed circuit breaker used for modeling is a thyristor-controlled type. Detail of the power circuit and its firing control part was demonstrated in graphical diagrams using elements of the MATLAB’s Power System Blockset (PSB). Test against fault conditions to verify its use was carried out. The results showed that, with a moderate sensing technique to monitor voltage and current of the protected feeder, the SSB can interrupt fault effectively.


Analysis of Perturbed Flows of a Second-Order Fluid using a 1D Hierarchical Model
Fernando Carapau

Abstract: The aim of this paper is to analyze the unsteady flow of a non-Newtonian incompressible second-order fluid in a straight rigid axisymmetric tube with circular crosssection of constant radius. To study this problem, we use the 1D nine-director Cosserat theory approach which reduces the exact three-dimensional equations to a system depending only on time and on a single spatial variable. From this onedimensional system we obtain the relationship between mean pressure gradient and volume flow rate over a finite section of the tube. Attention is focused on some numerical simulation of steady/unsteady flows for specific mean pressure gradient and on the analysis of perturbed flows.


A Method to Generate Random Deviates for a Fixed-Planned Rate Nonstationary Renewal Process
Marcos A. Masnik Ferreira, Celso Carnieri, Rui C. Botter

Abstract: The algorithms and techniques necessary to generate random deviates for a fixed-planned rate nonstationary renewal process (FPRNSRP) are presented in this paper. The authors define this process as a stochastic renewal process (RP) whose arrival rate by period is determined by a future demand. At first, the complete model is described and its objectives and variables are presented. After that, the algorithms and equations, that implement the solution using Mixed-Integer Linear Programming (MILP) and goal programming, are presented. It is also presented an algorithm to get a random sequence with a fixed number of values bounded into an interval fitted to a specified probability distribution.


About some Techniques of Improving Numerical Solutions Accuracy when Applying BEM
Luminita Grecu, Ion Vladimirescu

Abstract: The present paper is focused on analyzing different sources of errors that appear when using Boundary Element Method (BEM) to solve problems, and illustrating their influence on the numerical solutions accuracy. The study is made considering the errors that appear when BEM is used to solve a problem of compressible fluid flow. Analytical checking is used by referring to cases when the problem can be exactly solved, and so, the numerical solutions are compared with analytical solutions in order to check their accuracy. Some techniques to minimize the errors in order to get better numerical results are presented.


Innovative Design of Laminated Bamboo Furniture Using Finite Element Method
V. Laemlaksakul

Abstract: Development of the numerical evaluation method of the strength and the durability for the furniture was attempted using for an example the chair in order to utilize it for a quality control, a new products design. The objective of this research is to assess strength of laminated bamboo chair under static and dynamic loading and perform drop test analysis described in ISO 7173 (Furniture – Chairs and stools – Determination of strength and durability). The developed models establish procedure to perform virtual testing on laminated bamboo chair to reduce product design and testing time. The simulations are set up using a nonlinear dynamic finite element (FE) software which is equipped with both implicit and explicit solvers. This virtual testing result focused on the improve design and development of laminated bamboo chair through virtual testing.


Agent based Optimization and Management of Healthcare Processes at the Emergency Department
A. Daknou, H. Zgaya, S.Hammadi, H. Hubert

Abstract: In this paper, a Multi Agent System (MAS) is presented, aiming to minimize the waiting time of patient as well as the cost of care within emergency department. In such organization, a persistent need of efficiently activity scheduling process arises in order to take care of all arrival patients at the emergency department and to improve the quality of care. Software agents were adopted to provide the means to accomplish such real-time application, due to their autonomous, reactive and/or proactive nature, and their effectiveness in dynamic environments by incorporating coordination strategies. Specifically, the objective of the MAS is being able to represent the real conditions, courses, and the human decision behavior. The main aim of this paper is to present the overall design of the proposed MAS, emphasizing its architecture and the behavior of each agent of the model, as well as on the scheduling model which provide the activity scheduling process of care and the agent interaction protocol to ensure cooperation between agents that perform coordination tasks for the users, i.e. the medical staff needed to solve some problems at the emergency department.


The F.E.M. Study Concerning the Influence of Air Humidity about the Dynamical Flow around the Spatial Petroleum Coke Plant
Mihai D. L. Talu, Stefan D. L. Talu, Marin Bica

Abstract: The goal of this study was to investigate the influence of air humidity variation concerning the dynamical flow around of a petroleum coke plant. A finite element program was used for numerical analysis and partial results was exposed and compared with the experimental measurements. The 3D model of plant can be adapted for appropriate CAD applications.


    Paper Title, Authors, Abstract (Issue 4, Volume 2, 2008)


Applied Finite Element Method Simulation in 3D Printing
M. Iliescu, E. Nutu, B. Comanescu

Abstract: 3D printing, as part of Rapid Prototyping Technology, is a modern and efficient way of reducing product’s design and manufacture cycle. Its benefits in designing and manufacturing elements of a laser medical device are presented by this paper. Simulation involving computational fluid dynamics (CFD) and heat transfer phenomena, carried out with finite element method, has been applied in order to improve one of device’s elements shape, so as to get optimum laser device’s functional characteristics.


Study and Analysis of Production Dynamics with Designed Experimentation: Sizing of a Pull Drum Line Supermarket
R. Di Micco, E. Romano, L. C. Santillo

Abstract: To implement the strategy of the continuous flow process the goal is to aim to "Interdependent connected Processes" adopting the Pull System methodology in the Just in Time production environment. This logic is an ideal to tend, in which each individual operation is carried out only if necessary and if requested by next operation, in order to avoid overproduction, which is the worst waste.
This logic brings to a "pure" Pull System that is where the process is triggered by the customer request, going backward steps along the upstream up to raw materials supply. Pure Pull Systems are possible in theory but are very rare in practice. For example in manufacturing production situations in which the order is completed by forecasts sales at least at the beginning (push/pull systems) are most common.
These production systems therefore represent a model of operational excellence, which represents a target for PUSH systems. You want to produce a single piece at time, transferring it from a process to the next without waits. But process “links” means reducing the lead time and waits, getting to a flow that extends itself as the process reliability improves and waiting times such as set – up decrease. There are, however, areas where the flow is not practically possible, for example because numerous set-ups are needed or because "providers" do not send one piece at a time, working in batches. In this case you can control production implementing Pull/Push interfaces. A first solution is a system based on kanban that reintegrate a downstream station, known as "supermarket pull", where the continuous flow is interrupted and the process upstream works in batches according to a "pattern production", with a production managed by a wheel system, that is with a sequence set by the same upstream department and it is based upon a yearly model forecast of production suitably agreed among Marketing, Development and Production.
The creation of the model, its verification and its validation are explained in order to give an overview of the utilized model for further investigations.


Time and Space Complexity Improvements for a Grid Implementation of a Kohonen-Like Classification Algorithms on Sparse Data-Sets
Francesco Maiorana

Abstract: This paper presents a variation of a Kohonen self organizing feature map. From the proposed algorithm possible performance improvements are investigated in terms of time and space complexity taking advantage from a sparse input data set. The proposed variation has been tested on different datasets coming from case studies in the field of bioinformatics. The improvements make the application of the algorithms feasible to massive document collections. The application of the proposed improvements for grid implementations could be beneficial to reduce the computing element demand.


VV&A of Complex Modeling and Simulation Systems: Methodologies and Case Studies
Matteo Ugo Brandolini, Chiara Briano, Enrico Briano, Roberto Revetria

Abstract: During the conceptual modeling, the design and the development of Modeling and Simulation Systems, the Verification and Validation phases should be taken into account because they are fundamental for clearly understanding if the simulated system is corresponding to real one.
In this work the authors proposed a short overview of methodologies, procedures and techniques used for the Verification and Validation (V&V) phases in three different cases corresponding to three simulation models. The first case involves a simulation model developed for the maintenance management (both corrective and preventive) of motorways typical sets of items (TVCC, smoke detectors, variable message panels, etc…) subjected to failures and that needs to be planned at regular intervals. The second case is about a simulation model that identifies the probability of a ship to be detected by a submarine dynamically into a specific naval scenario. The third and last case focuses on a human behavior simulation model developed in order to evaluate alternative emergency management policies for in tunnels.
For each case, a different set of validation and verification methodologies, procedures and techniques has been applied depending on Verification (conceptual model, design and implementation) and Validation (structural and results) processes.


A Study of Crowd Behavior in Emergency Tunnel Procedures
Enrico Briano, Roberto Revetria

Abstract: In the last years unfortunately some tragedies have occurred inside tunnels (i.e. Mont Blanc Road Tunnel in 1999 and others) causing many deaths and serious injuries for several people, so a greater sensibility towards safety, both in terms of infrastructure and devices but also in terms of people awareness, has been grown. The authors propose to study the importance of the human behavior and all the factors involving one’s choices during the evacuation phase inside a long motorway tunnel.
In order to take into account all the criteria that affect the choices, especially human factors typical of a PECS model, which involves Physical, Emotional, Cognitive and Social behaviors, a multicriteria analysis has been conducted, using Modeling and Simulation (M&S) reproducing a decision network thanks to Saaty’s AHP (Analytic Hierarchic Process).
This model is quite similar to the classical PECS models proposed such as Adam Model, in which Adam, thanks to his attributes and knowledge, tries to survive inside his world exploring it and avoiding all the potential dangerous situations; in fact, the person inside the tunnel, thanks to his/her physical, emotional, cognitive and social attitudes (these ones not present in Adam’s world where he is alone), has to manage how to survive from a fire or a smoke intoxication reaching safety as soon as he can even sacrificing, at least, an expensive good as a car is.


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