Modelling and Simulation in Engineering The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Wind Load Reduction in Hollow Panel Arrayed Set Sun, 18 Sep 2016 08:04:28 +0000 Reducing the wind loading of photovoltaic structures is crucial for their structural stability. In this study, two solar panel arrayed sets were numerically tested for load reduction purposes. All panel surface areas of the arrayed set are exposed to the wind similarly. The first set was comprised of conventional panels. The second one was fitted with square holes located right at the gravity center of each panel. Wind flow analysis on standalone arrayed set of panels at fixed inclination was carried out to calculate the wind loads at various flow velocities and directions. The panels which included holes reduced the velocity in the downwind flow region and extended the low velocity flow region when compared to the nonhole panels. The loading reduction, in the arrayed set of panels with holes ranged from 0.8% to 12.53%. The maximum load reduction occurred at 6.0 m/s upwind velocity and 120.0° approach angle. At 30.00 approach angle, wind load increased but marginally. Current research work findings suggest that the panel holes greatly affect the flow pattern and subsequently the wind load reduction. The computational analysis indicates that it is possible to considerably reduce the wind loading using panels with holes. Michalina Markousi, Dimitrios K. Fytanidis, and Johannes V. Soulis Copyright © 2016 Michalina Markousi et al. All rights reserved. Forward VNS, Reverse VNS, and Multi-VNS Algorithms for Job-Shop Scheduling Problem Thu, 08 Sep 2016 13:49:33 +0000 This paper proposes a number of forward VNS and reverse VNS algorithms for job-shop scheduling problem. The forward VNS algorithms are the variable neighborhood search algorithms applied to the original problem (i.e., the problem instance with the original precedence constraints). The reverse VNS algorithms are the variable neighborhood search algorithms applied to the reversed problem (i.e., the problem instance with the reversed precedence constraints). This paper also proposes a multi-VNS algorithm which assigns an identical initial solution-representing permutation to the selected VNS algorithms, runs these VNS algorithms, and then uses the best solution among the final solutions of all selected VNS algorithms as its final result. The aim of the multi-VNS algorithm is to utilize each single initial solution-representing permutation most efficiently and thus receive its best result in return. Pisut Pongchairerks Copyright © 2016 Pisut Pongchairerks. All rights reserved. MARS: An Educational Environment for Multiagent Robot Simulations Thu, 08 Sep 2016 11:25:01 +0000 Undergraduate robotics students often find it difficult to design and validate control algorithms for teams of mobile robots. This is mainly due to two reasons. First, very rarely, educational laboratories are equipped with large teams of robots, which are usually expensive, bulky, and difficult to manage and maintain. Second, robotics simulators often require students to spend much time to learn their use and functionalities. For this purpose, a simulator of multiagent mobile robots named MARS has been developed within the Matlab environment, with the aim of helping students to simulate a wide variety of control algorithms in an easy way and without spending time for understanding a new language. Through this facility, the user is able to simulate multirobot teams performing different tasks, from cooperative to competitive ones, by using both centralized and distributed controllers. Virtual sensors are provided to simulate real devices. A graphical user interface allows students to monitor the robots behaviour through an online animation. Marco Casini and Andrea Garulli Copyright © 2016 Marco Casini and Andrea Garulli. All rights reserved. Modelling a Coupled Thermoelectromechanical Behaviour of Contact Elements via Fractal Surfaces Thu, 25 Aug 2016 08:55:41 +0000 A three-dimensional coupled thermoelectromechanical model for electrical connectors is here proposed to evaluate local stress and temperature distributions around the contact area of electric connectors under different applied loads. A micromechanical numerical model has been developed by merging together the contact theory approach, which makes use of the so-called roughness parameters obtained from experimental measurements on real contact surfaces, with the topology description of the rough surface via the theory of fractal geometry. Particularly, the variation of asperities has been evaluated via the Weierstrass-Mandelbrot function. In this way the micromechanical model allowed for an upgraded contact algorithm in terms of effective contact area and thermal and electrical contact conductivities. Such an algorithm is subsequently implemented to construct a global model for performing transient thermoelectromechanical analyses without the need of simulating roughness asperities of contact surfaces, so reducing the computational cost. A comparison between numerical and analytical results shows that the adopted procedure is suitable to simulate the transient thermoelectromechanical response of electric connectors. G. Mazzucco, F. Moro, and M. Guarnieri Copyright © 2016 G. Mazzucco et al. All rights reserved. Numerical Estimation of Effective Mechanical Properties for Reinforced Plexiglas in the Two-Dimensional Case Wed, 24 Aug 2016 10:40:36 +0000 The paper describes an algorithm for numerical estimation of effective mechanical properties in two-dimensional case, considering finite strains. The algorithm is based on consecutive application of different boundary conditions to representative surface elements (RSEs) in terms of displacements, solution of elastic boundary value problem for each case, and averaging the stress field obtained. Effective properties are estimated as a quadratic dependence of the second Piola-Kirchhoff stress tensor upon the Green strain tensor. The results of numerical estimation of effective mechanical properties of plexiglas, reinforced with steel wire, are presented at finite strains. Numerical calculations were performed with the help of CAE Fidesys using the finite element method. The dependence of the effective properties of reinforced plexiglas upon the concentration of wires and the shape of wire cross section is investigated. In particular, it was found that the aspect ratio of reinforcing wire cross section has the most significant impact on effective moduli characterizing the material properties in the direction of larger side of the cross section. The obtained results allow one to estimate the influence of nonlinear effects upon the mechanical properties of the composite. Vladimir Levin, Ignatiy Vdovichenko, Anatoly Vershinin, Maksim Yakovlev, and Konstantin Zingerman Copyright © 2016 Vladimir Levin et al. All rights reserved. Studies of Two-Phase Flow at a Chute Aerator with Experiments and CFD Modelling Tue, 23 Aug 2016 06:22:40 +0000 The chute aerator of a spillway is a structure in such a sense that air is, in the intense emulsification, entrained into the high-velocity water flow. Correctly predicting the air entrainment and two-phase flow pattern at the aerator would contribute to reliable spillway operation. Based on experimental data, 2D numerical simulations are preformed to predict streamwise air concentrations in the aerated flow, in which a two-fluid model is used. Depending on the air bubble size, relatively good agreement is seen with the experiments in the air cavity zone. The simulations give rise to higher air concentration downstream of the cavity, which is presumably due to underestimation of the interfacial forces in the two-fluid model. Penghua Teng, James Yang, and Michael Pfister Copyright © 2016 Penghua Teng et al. All rights reserved. Fire Spalling Prevention via Polypropylene Fibres: A Meso- and Macroscale Approach Mon, 22 Aug 2016 09:12:43 +0000 A deep understanding of concrete at the mesoscale level is essential for a better comprehension of several concrete phenomena, such as creep, damage, and spalling. The latter one specifically corresponds to the separation of pieces of concrete from the surface of a structural element when it is exposed to high and rapidly rising temperatures; for this phenomenon a mesoscopic approach is fundamental since aggregates performance and their thermal properties play a crucial role. To reduce the risk of spalling of a concrete material under fire condition, the inclusion of a low dosage of polypropylene fibres in the mix design of concrete is largely recognized. PP fibres in fact evaporate above certain temperatures, thus increasing the porosity and reducing the internal pressure in the material by an increase of the voids connectivity in the cement paste. In this work, the contribution of polypropylene fibres on concrete behaviour, if subjected to elevated thermal ranges, has been numerically investigated thanks to a coupled hygrothermomechanical finite element formulation. Numerical analyses at the macro- and mesoscale levels have been performed. G. Mazzucco and G. Xotta Copyright © 2016 G. Mazzucco and G. Xotta. All rights reserved. A Review on Radiation Damage in Concrete for Nuclear Facilities: From Experiments to Modeling Mon, 15 Aug 2016 11:19:08 +0000 Concrete is a relatively cheap material and easy to be cast into variously shaped structures. Its good shielding properties against neutrons and gamma-rays, due to its intrinsic water content and relatively high-density, respectively, make it the most widely used material for radiation shielding also. Concrete is so chosen as biological barrier in nuclear reactors and other nuclear facilities where neutron sources are hosted. Theoretical formulas are available in nuclear engineering manuals for the optimum thickness of shielding for radioprotection purposes; however they are restricted to one-dimensional problems; besides the basic empirical constants do not consider radiation damage effects, while its long-term performance is crucial for the safe operation of such facilities. To understand the behaviour of concrete properties, it is necessary to examine concrete strength and stiffness, water behavior, volume change of cement paste, and aggregate under irradiated conditions. Radiation damage process is not well understood yet and there is not a unified approach to the practical and predictive assessment of irradiated concrete, which combines both physics and structural mechanics issues. This paper provides a collection of the most distinguished contributions on this topic in the past 50 years. At present a remarkable renewed interest in the subject is shown. Beatrice Pomaro Copyright © 2016 Beatrice Pomaro. All rights reserved. Harmonic Impact of Plug-In Hybrid Electric Vehicle on Electric Distribution System Mon, 15 Aug 2016 11:13:20 +0000 This paper presents the harmonic effects of plug-in hybrid electric vehicles (PHEV) on the IEEE 37-bus distribution system at different PHEV penetration levels considering a practical daily residential load shape. The PHEV is modeled as a current harmonic source by using the Open-Source Distribution System Simulator (OpenDSS) and DSSimpc software. Time series harmonic simulation was conducted to investigate the harmonic impact of PHEV on the system by using harmonic data obtained from a real electric vehicle. Harmonic effects on the system voltage profile and circuit power losses are also investigated by using OpenDSS and MATLAB software. Current/voltage total harmonic distortion (THD) produced from the large scale of PHEV is investigated. Test results show that the voltage and current THDs are increased up to 9.5% and 50%, respectively, due to high PHEV penetrations and these THD values are significantly larger than the limits prescribed by the IEEE standards. A. Aljanad and Azah Mohamed Copyright © 2016 A. Aljanad and Azah Mohamed. All rights reserved. Automated Search-Based Robustness Testing for Autonomous Vehicle Software Sun, 07 Aug 2016 14:02:18 +0000 Autonomous systems must successfully operate in complex time-varying spatial environments even when dealing with system faults that may occur during a mission. Consequently, evaluating the robustness, or ability to operate correctly under unexpected conditions, of autonomous vehicle control software is an increasingly important issue in software testing. New methods to automatically generate test cases for robustness testing of autonomous vehicle control software in closed-loop simulation are needed. Search-based testing techniques were used to automatically generate test cases, consisting of initial conditions and fault sequences, intended to challenge the control software more than test cases generated using current methods. Two different search-based testing methods, genetic algorithms and surrogate-based optimization, were used to generate test cases for a simulated unmanned aerial vehicle attempting to fly through an entryway. The effectiveness of the search-based methods in generating challenging test cases was compared to both a truth reference (full combinatorial testing) and the method most commonly used today (Monte Carlo testing). The search-based testing techniques demonstrated better performance than Monte Carlo testing for both of the test case generation performance metrics: (1) finding the single most challenging test case and (2) finding the set of fifty test cases with the highest mean degree of challenge. Kevin M. Betts and Mikel D. Petty Copyright © 2016 Kevin M. Betts and Mikel D. Petty. All rights reserved. Some Aspects of Structural Modeling of Damage Accumulation and Fracture Processes in Metal Structures at Low Temperature Wed, 27 Jul 2016 11:23:44 +0000 The problem of brittle fracture of structures at low temperature conditions connected to damage accumulation and ductile-brittle transition in metals. The data for locomotive tire contact impact fatigue and spalling are presented. The results of experimental testing showed the impact toughness drop at low temperature. The internal friction method was applied to revealing of the mechanism of dislocation microstructure changes during the low temperature ductile-brittle transition. It has been shown for the first time that the transition is not connected to interatomic interactions but stipulated by thermofluctuation on nucleus such as microcracks and by their further growth and coalescence. From now on, the proposed mechanism would be used for theoretical and numerical modeling of damage accumulation and fracture in materials. Valeriy Lepov, Albert Grigoriev, Valentina Achikasova, and Kyunna Lepova Copyright © 2016 Valeriy Lepov et al. All rights reserved. Comparison of Parametric and Nonparametric Methods for Analyzing the Bias of a Numerical Model Mon, 30 May 2016 07:19:00 +0000 Numerical models are presently applied in many fields for simulation and prediction, operation, or research. The output from these models normally has both systematic and random errors. The study compared January 2015 temperature data for Uganda as simulated using the Weather Research and Forecast model with actual observed station temperature data to analyze the bias using parametric (the root mean square error (RMSE), the mean absolute error (MAE), mean error (ME), skewness, and the bias easy estimate (BES)) and nonparametric (the sign test, STM) methods. The RMSE normally overestimates the error compared to MAE. The RMSE and MAE are not sensitive to direction of bias. The ME gives both direction and magnitude of bias but can be distorted by extreme values while the BES is insensitive to extreme values. The STM is robust for giving the direction of bias; it is not sensitive to extreme values but it does not give the magnitude of bias. The graphical tools (such as time series and cumulative curves) show the performance of the model with time. It is recommended to integrate parametric and nonparametric methods along with graphical methods for a comprehensive analysis of bias of a numerical model. Isaac Mugume, Charles Basalirwa, Daniel Waiswa, Joachim Reuder, Michel d. S. Mesquita, Sulin Tao, and Triphonia J. Ngailo Copyright © 2016 Isaac Mugume et al. All rights reserved. Analysis of Muscle Activity Utilizing Bench Presses in the AnyBody Simulation Modelling System Wed, 11 May 2016 10:06:55 +0000 Using the AnyBody human modeling system with identical weights and varying grip distance (40.0 cm, 50.0 cm, and 60.0 cm), the stress distribution for the pectoralis and the muscle of upper extremity during a bench press was simulated, and the surface myoelectricity (EMG) method was validated. Methods. The physical parameters driving the model of the human body were selected as weights of 35.0% (25.0 kg) and grip distances. Conclusion. The validation of AnyBody software was proved as a high validity by using EMG test of four muscles’ activity compared to AnyBody software. During a bench press, the pectoralis major is the main muscle, the pectoralis major discharge increases with the height of barbell increases, and the pectoralis major discharge decreases as the short grip width increases. When the grip width equals the shoulder width, the value of pectoralis minor is lowest; when the grip width is smaller or larger than the shoulder width, the value is larger. As the short grip distance increases, the discharge of posterior deltoid muscle and triceps surface myoelectricity increases; thus, as the short grip distance increases, the deltoid muscle and triceps assist the pectoralis major during a bench press. Zhongqiu Ji, Huihui Wang, Guiping Jiang, and Lin Li Copyright © 2016 Zhongqiu Ji et al. All rights reserved. Development of Constitutive Model for Precast Prestressed Concrete Segmental Columns Sun, 27 Mar 2016 07:11:55 +0000 The interest of using precast segmental columns in construction of concrete bridges has significantly increased in recent years. One research area of concrete bridges is the application of Precast Prestressed Concrete Segmental (PPCS) Column in any structural analysis software or FE program code. Modeling a PPCS column, which consists of various materials with interaction between them, is complicated and time-consuming. This research attempts to formulate the stiffness matrix of PPCS columns in order to form the constitutive model in linear form to evaluate the response of the columns. A two-dimensional finite element model is presented in the finite element package ANSYS. Parametric studies are conducted by finite element models to verify the constitutive models for the PPCS column with a different number of concrete segments. Comparison between the constitutive model and the FE program results indicates that the constitutive model is accurate enough to predict the deformation of the PPCS columns. M. Hafezolghorani Esfahani, F. Hejazi, R. Vaghei, E. Nikbakht, and D. C. J. Tze Copyright © 2016 M. Hafezolghorani Esfahani et al. All rights reserved. Prediction on Power Produced from Power Turbine as a Waste Heat Recovery Mechanism on Naturally Aspirated Spark Ignition Engine Using Artificial Neural Network Tue, 22 Mar 2016 11:47:36 +0000 The waste heat from exhaust gases represents a significant amount of thermal energy, which has conventionally been used for combined heating and power applications. This paper explores the performance of a naturally aspirated spark ignition engine equipped with waste heat recovery mechanism (WHRM) in a sedan car. The amount of heat energy from exhaust is presented and the experimental test results suggest that the concept is thermodynamically feasible and could significantly enhance the system performance depending on the load applied to the engine. However, the existence of WHRM affects the performance of engine by slightly reducing the power. The simulation method is created using an artificial neural network (ANN) which predicts the power produced from the WHRM. Safarudin Gazali Herawan, Abdul Hakim Rohhaizan, Ahmad Faris Ismail, Shamsul Anuar Shamsudin, Azma Putra, Mohd Tahir Musthafah, and Ardika Ridal Awang Copyright © 2016 Safarudin Gazali Herawan et al. All rights reserved. Development of the Object-Oriented Dynamic Simulation Models Using Visual C++ Freeware Wed, 16 Mar 2016 13:44:36 +0000 The paper mostly focuses on the methodological and programming aspects of developing a versatile desktop framework to provide the available basis for the high-performance simulation of dynamical models of different kinds and for diverse applications. So the paper gives some basic structure for creating a dynamical simulation model in C++ which is built on the Win32 platform with an interactive multiwindow interface and uses the lightweight Visual C++ Express as a free integrated development environment. The resultant simulation framework could be a more acceptable alternative to other solutions developed on the basis of commercial tools like Borland C++ or Visual C++ Professional, not to mention the domain specific languages and more specialized ready-made software such as Matlab, Simulink, and Modelica. This approach seems to be justified in the case of complex research object-oriented dynamical models having nonstandard structure, relationships, algorithms, and solvers, as it allows developing solutions of high flexibility. The essence of the model framework is shown using a case study of simulation of moving charged particles in the electrostatic field. The simulation model possesses the necessary visualization and control features such as an interactive input, real time graphical and text output, start, stop, and rate control. Alexander I. Kozynchenko and Sergey A. Kozynchenko Copyright © 2016 Alexander I. Kozynchenko and Sergey A. Kozynchenko. All rights reserved. An Adaptive Object Tracking Using Kalman Filter and Probability Product Kernel Wed, 16 Mar 2016 08:16:00 +0000 We present a new method for object tracking; we use an efficient local search scheme based on the Kalman filter and the probability product kernel (KFPPK) to find the image region with a histogram most similar to the histogram of the tracked target. Experimental results verify the effectiveness of this proposed system. Hamd Ait Abdelali, Fedwa Essannouni, Leila Essannouni, and Driss Aboutajdine Copyright © 2016 Hamd Ait Abdelali et al. All rights reserved. Numerical Simulations as Tool to Predict Chemical and Radiological Hazardous Diffusion in Case of Nonconventional Events Thu, 21 Jan 2016 13:09:45 +0000 CFD (Computational Fluid Dynamics) simulations are widely used nowadays to predict the behaviour of fluids in pure research and in industrial applications. This approach makes it possible to get quantitatively meaningful results, often in good agreement with the experimental ones. The aim of this paper is to show how CFD calculations can help to understand the time evolution of two possible CBRNe (Chemical-Biological-Radiological-Nuclear-explosive) events: (1) hazardous dust mobilization due to the interaction between a jet of air and a metallic powder in case of a LOVA (Loss Of Vacuum Accidents) that is one of the possible accidents that can occur in experimental nuclear fusion plants; (2) toxic gas release in atmosphere. The scenario analysed in the paper has consequences similar to those expected in case of a release of dangerous substances (chemical or radioactive) in enclosed or open environment during nonconventional events (like accidents or man-made or natural disasters). J.-F. Ciparisse, A. Malizia, L. A. Poggi, O. Cenciarelli, M. Gelfusa, M. C. Carestia, D. Di Giovanni, S. Mancinelli, L. Palombi, C. Bellecci, and P. Gaudio Copyright © 2016 J.-F. Ciparisse et al. All rights reserved. Thermoelectric Modeling and Online SOC Estimation of Li-Ion Battery for Plug-In Hybrid Electric Vehicles Wed, 06 Jan 2016 11:12:33 +0000 The increasing oil price, energy demand, and environmental concern are leading to a global switch towards Plug-In Hybrid Electric Vehicles (PHEVs). In a PHEV, Li-ion battery is considered as the primary propelling source. Therefore, an accurate battery model is required to predict the characteristic and dynamic behavior of a battery. This paper presents a highly effective thermoelectric model of Li-ion battery developed in Simulink. An algorithm is proposed for estimation of state of charge (SOC) and open circuit voltage (OCV) adaptively to notify the exact SOC level for better utilization of battery power and optimal vehicle performance. Thermal behavior of Li-ion battery is investigated for wide temperature range and its effect on resistance, capacity, and OCV is recorded. The minimum SOC level to which battery can get depleted is calculated using gradient method. The proposed simulation results are analyzed with those of earlier models and found to be better. Aishwarya Panday, Hari Om Bansal, and Pramod Srinivasan Copyright © 2016 Aishwarya Panday et al. All rights reserved. A Comparative Study of Multiple Object Detection Using Haar-Like Feature Selection and Local Binary Patterns in Several Platforms Thu, 31 Dec 2015 11:32:38 +0000 Object detection has been attracting much interest due to the wide spectrum of applications that use it. It has been driven by an increasing processing power available in software and hardware platforms. In this work we present a developed application for multiple objects detection based on OpenCV libraries. The complexity-related aspects that were considered in the object detection using cascade classifier are described. Furthermore, we discuss the profiling and porting of the application into an embedded platform and compare the results with those obtained on traditional platforms. The proposed application deals with real-time systems implementation and the results give a metric able to select where the cases of object detection applications may be more complex and where it may be simpler. Souhail Guennouni, Ali Ahaitouf, and Anass Mansouri Copyright © 2015 Souhail Guennouni et al. All rights reserved. Optimized Sizing, Selection, and Economic Analysis of Battery Energy Storage for Grid-Connected Wind-PV Hybrid System Thu, 24 Dec 2015 09:45:43 +0000 Energy storages are emerging as a predominant sector for renewable energy applications. This paper focuses on a feasibility study to integrate battery energy storage with a hybrid wind-solar grid-connected power system to effectively dispatch wind power by incorporating peak shaving and ramp rate limiting. The sizing methodology is optimized using bat optimization algorithm to minimize the cost of investment and losses incurred by the system in form of load shedding and wind curtailment. The integrated system is then tested with an efficient battery management strategy which prevents overcharging/discharging of the battery. In the study, five major types of battery systems are considered and analyzed. They are evaluated and compared based on technoeconomic and environmental metrics as per Indian power market scenario. Technoeconomic analysis of the battery is validated by simulations, on a proposed wind-photovoltaic system in a wind site in Southern India. Environmental analysis is performed by evaluating the avoided cost of emissions. Hina Fathima and K. Palanisamy Copyright © 2015 Hina Fathima and K. Palanisamy. All rights reserved. Effect of Coastal Waves on Hydrodynamics in One-Inlet Coastal Nador Lagoon, Morocco Thu, 17 Dec 2015 07:09:00 +0000 Nador lagoon is a coastal system connected to the sea through a narrow and shallow inlet; understanding its hydraulic performance is required for its design and operation. This paper investigates the hydrodynamic impacts of the whole lagoon due to tidal waves using a numerical approach. In this study we use a two-dimensional, depth-averaged hydrodynamic model based on so-called shallow water equations solved within triangular mesh by a developed efficient finite volume method. The method was calibrated and validated against observed data and applied to analyze and predict water levels, tidal currents, and wind effects within the lagoon. Two typical idealized scenarios were investigated: tide only and tide with wind forcing. The predicted sea surface elevations and current speeds have been presented during a typical tidal period and show correct physics in different scenarios. Jeyar Mohammed, Elmiloud Chaabelasri, and Najim Salhi Copyright © 2015 Jeyar Mohammed et al. All rights reserved. Uncertainty Analysis of Mixing Efficiency Variation in Passive Micromixers due to Geometric Tolerances Tue, 15 Dec 2015 12:52:08 +0000 The geometric layout is the key factor for enhancing the efficiency of the fluid mixing in passive micromixers. Therefore, by adjusting the geometric design and by controlling the geometric parameters, one can enhance the mixing process. However, through any fabrication process, the geometric parameters present slight, inherent variation from the designed values than might affect the performance of the micromixer. This paper proposes a numerical study on the influence of the unavoidable geometric tolerances on the mixing efficiency in passive micromixers. A probabilistic simulation model, based on the Monte Carlo method, is developed and implemented for this purpose. An uncertainty simulation model shows that significant deviations from the deterministic design can appear due to small variations in the geometric parameters values and demonstrates how a more realistic mixing performance can be estimated. Irina Stanciu Copyright © 2015 Irina Stanciu. All rights reserved. Steady-State Analysis and Comparison of Control Strategies for PMSM Mon, 14 Dec 2015 06:57:12 +0000 Permanent Magnet Synchronous Motor (PMSM) has been considered as the best choice for numerous applications. To make PMSM a high performance drive, effective control system is required. Vector control is accepted widely due to its decoupling effect but it is not the only performance requirement. Additional control methods such as constant torque angle control (CTAC), optimum torque per ampere control (OTPAC), unity power factor control (UPFC), constant mutual flux linkages control (CMFLC), and angle control of air gap flux and current phasor (ACAGF) can also be implemented. This paper therefore presents some important control strategies for PMSM along with merits and limitations which provide a wide variety of control choices in many applications. The performance characteristics for each strategy under steady state are modelled and simulated in MATLAB environment. Based on the simulation results, a conclusion is drawn that OTPAC is superior in normalized torque per unit normalized stator current () ratio whereas UPFC yields very low ratio. In addition, performances of these control strategies are compared, which is a key to select optimum strategy depending on requirements. Based on the comparative study, it can be concluded that CMFLC is superior to CTAC, ACAGF, OTPAC, and UPFC. Hence, it can be a good control strategy to consider. Jyoti Agrawal and Sanjay Bodkhe Copyright © 2015 Jyoti Agrawal and Sanjay Bodkhe. All rights reserved. A Novel Geometric Modification to the Newton-Secant Method to Achieve Convergence of Order and Its Dynamics Wed, 09 Dec 2015 08:10:37 +0000 A geometric modification to the Newton-Secant method to obtain the root of a nonlinear equation is described and analyzed. With the same number of evaluations, the modified method converges faster than Newton’s method and the convergence order of the new method is . The numerical examples and the dynamical analysis show that the new method is robust and converges to the root in many cases where Newton’s method and other recently published methods fail. Gustavo Fernández-Torres Copyright © 2015 Gustavo Fernández-Torres. All rights reserved. A New Approach to Improve Accuracy of Grey Model GMC in Time Series Prediction Mon, 07 Dec 2015 12:47:23 +0000 This paper presents a modified grey model GMC for use in systems that involve one dependent system behavior and relative factors. The proposed model was developed from the conventional GMC model in order to improve its prediction accuracy by modifying the formula for calculating the background value, the system of parameter estimation, and the model prediction equation. The modified GMC model was verified by two cases: the study of forecasting CO2 emission in Thailand and forecasting electricity consumption in Thailand. The results demonstrated that the modified GMC model was able to achieve higher fitting and prediction accuracy compared with the conventional GMC and D-GMC models. Sompop Moonchai and Wanwisa Rakpuang Copyright © 2015 Sompop Moonchai and Wanwisa Rakpuang. All rights reserved. A Segmental Approach with SWT Technique for Denoising the EOG Signal Tue, 10 Nov 2015 14:03:47 +0000 The Electrooculogram (EOG) signal is often contaminated with artifacts and power-line while recording. It is very much essential to denoise the EOG signal for quality diagnosis. The present study deals with denoising of noisy EOG signals using Stationary Wavelet Transformation (SWT) technique by two different approaches, namely, increasing segments of the EOG signal and different equal segments of the EOG signal. For performing the segmental denoising analysis, an EOG signal is simulated and added with controlled noise powers of 5 dB, 10 dB, 15 dB, 20 dB, and 25 dB so as to obtain five different noisy EOG signals. The results obtained after denoising them are extremely encouraging. Root Mean Square Error (RMSE) values between reference EOG signal and EOG signals with noise powers of 5 dB, 10 dB, and 15 dB are very less when compared with 20 dB and 25 dB noise powers. The findings suggest that the SWT technique can be used to denoise the noisy EOG signal with optimum noise powers ranging from 5 dB to 15 dB. This technique might be useful in quality diagnosis of various neurological or eye disorders. Naga Rajesh Copyright © 2015 Naga Rajesh. All rights reserved. Numerical Investigation on Vortex Shedding from a Hydrofoil with a Beveled Trailing Edge Tue, 01 Sep 2015 09:53:18 +0000 To better understand the vortex shedding mechanism and to assess the capability of our numerical methodology, we conducted numerical investigations of vortex shedding from truncated and oblique trailing edges of a modified NACA 0009 hydrofoil. The hybrid particle-mesh method and the vorticity-based subgrid scale model were employed to simulate these turbulent wake flows. The hybrid particle-mesh method combines the vortex-in-cell and the penalization methods. We have implemented numerical schemes to more efficiently use available computational resources. In this study, we numerically investigated vortex shedding from various beveled trailing edges at a Reynolds number of 106. We then compared the numerical results with the experimental data, which show good agreement. We also conducted numerical simulations of wakes behind the hydrofoil at rest in periodically varying flows. Results reveal that vortex shedding is affected by the periodicity of a free-stream flow, as well as the trailing-edge shape. Seung-Jae Lee, Jun-Hyeok Lee, and Jung-Chun Suh Copyright © 2015 Seung-Jae Lee et al. All rights reserved. Continuous Finite Element Methods of Molecular Dynamics Simulations Thu, 13 Aug 2015 13:54:26 +0000 Molecular dynamics simulations are necessary to perform very long integration times. In this paper, we discuss continuous finite element methods for molecular dynamics simulation problems. Our numerical results about diatomic molecular system and triatomic molecules show that linear finite element and quadratic finite element methods can better preserve the motion characteristics of molecular dynamics, that is, properties of energy conservation and long-term stability. So finite element method is also a reliable method to simulate long-time classical trajectory of molecular systems. Qiong Tang, Luohua Liu, and Yujun Zheng Copyright © 2015 Qiong Tang et al. All rights reserved. Consistent Weighted Average Flux of Well-Balanced TVD-RK Discontinuous Galerkin Method for Shallow Water Flows Tue, 07 Jul 2015 10:28:51 +0000 A well-balanced scheme with total variation diminishing Runge-Kutta discontinuous Galerkin (TVD-RK DG) method for solving shallow water equations is presented. Generally, the flux function at cell interface in the TVD-RK DG scheme is approximated by using the Harten-Lax-van Leer (HLL) method. Here, we apply the weighted average flux (WAF) which is higher order approximation instead of using the HLL in the TVD-RK DG method. The consistency property is shown. The modified well-balanced technique for flux gradient and source terms under the WAF approximations is developed. The accuracy of numerical solutions is demonstrated by simulating dam-break flows with the flat bottom. The steady solutions with shock can be captured correctly without spurious oscillations near the shock front. This presents the other flux approximations in the TVD-RK DG method for shallow water simulations. Thida Pongsanguansin, Montri Maleewong, and Khamron Mekchay Copyright © 2015 Thida Pongsanguansin et al. All rights reserved.