Modelling and Simulation in Engineering The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Computational Analysis to Factor Wind into the Design of an Architectural Environment Tue, 14 Apr 2015 08:37:39 +0000 The effect of wind distribution on the architectural domain of the Bahrain Trade Centre was numerically analysed using computational fluid dynamics (CFD). Using the numerical data, the power generation potential of the building-integrated wind turbines was determined in response to the prevailing wind direction. The three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations along with the momentum and continuity equations were solved for obtaining the velocity and pressure field. Simulating a reference wind speed of 6 m/s, the findings from the study quantified an estimate power generation of 6.4 kW indicating a capacity factor of 2.9% for the benchmark model. At the windward side of the building, it was observed that the layers of turbulence intensified in inverse proportion to the height of the building with an average value of 0.45 J/kg. The air velocity was found to gradually increase in direct proportion to the elevation with the turbine located at higher altitude receiving maximum exposure to incoming wind. This work highlighted the potential of using advanced computational fluid dynamics in order to factor wind into the design of any architectural environment. Hassam Nasarullah Chaudhry, John Kaiser Calautit, and Ben Richard Hughes Copyright © 2015 Hassam Nasarullah Chaudhry et al. All rights reserved. Study on Hot Deformation Behavior of 7085 Aluminum Alloy during Backward Extrusion Process Sun, 29 Mar 2015 11:39:04 +0000 Compression test was carried out and the true stress-strain curves were obtained from the hot compression of 7085 alloy. A numerical simulation on the deformation behavior of 7085 aluminum alloy during the backward extrusion was also performed by finite element method. The results show that dynamic recrystallization occurs in the hot compression of 7085 alloy and the peak stress reaches higher values as the strain rate increases and deformation temperature decreases. The backward extrusion processes include contact deformation, initial deformation, and steady deformation. Severe plastic deformation of shear and compression occurs when the metal flowed into the channel between fillet of punch and wall of die so that the grain size can be refined by backward extrusion. The deformation in the region of top of wall is too small to meet the mechanical properties of requirements and the metal usually needs to be trimmed. The experiments with the same parameters as simulation had been carried out and the experimental cup after extrusion has better quality. R. B. Mei, Y. X. Du, L. Bao, X. Y. Zhang, B. Zhang, and Z. J. Zhou Copyright © 2015 R. B. Mei et al. All rights reserved. Analysis on Cooling Effect of Crushed-Rocks Embankment of Qinghai-Tibet High-Grade Road Thu, 12 Mar 2015 08:23:07 +0000 In order to study the cooling effect of the crushed-rocks embankment, the permeability and the inertial resistance coefficient were measured by the wind tunnel test of spheres with a diameter of 20 cm, and then the stabilities of the closed crushed-rocks embankment with the wide pavement, the closed crushed-rocks embankment with the narrow pavement, and the duct-ventilated and closed crushed-rocks embankment were calculated. In the next 50 years, assuming that the temperature in Qinghai-Tibet plateau will rise by 2.6°C condition, the cooling effects of these three special high-grade embankment structures were studied. The test results and the numerical calculation results show that the relationship between pressure gradient and seepage velocity in the spheres layer diverges completely from Darcy’s law, and it shows a nice quadratic nonlinear relationship. Stabilities of those two closed crushed-rock embankments without the duct-ventilated structure could be destroyed because of the high permafrost temperature under embankments. The duct-ventilated and closed crushed-rocks embankment can cool down the permafrost effectively and raise the permafrost table and ensure the long-term thermal stability of permafrost under road. Dongqing Li, Kun Zhang, Gangqiang Tong, Feng Ming, and Xing Huang Copyright © 2015 Dongqing Li et al. All rights reserved. Self-Organizing Construction Method of Offshore Structures by Cellular Automata Model Mon, 09 Mar 2015 06:58:15 +0000 We propose a new algorithm to build self-organizing and self-repairing marine structures on the ocean floor, where humans and remotely operated robots cannot operate. The proposed algorithm is based on the one-dimensional cellular automata model and uses simple transition rules to produce various complex patterns. This cellular automata model can produce various complex patterns like sea shells with simple transition rules. The model can simulate the marine structure construction process with distributed cooperation control instead of central control. Like living organism is constructed with module called cell, we assume that the self-organized structure consists of unified modules (structural units). The units pile up at the bottom of the sea and a structure with the appropriate shape eventually emerges. Using the attribute of emerging patterns in the one-dimensional cellular automata model, we construct specific structures based on the local interaction of transition rules without using complex algorithms. Furthermore, the model requires smaller communication data among the units because it only relies on communication between adjacent structural units. With the proposed algorithm, in the future, it will be possible to use self-assembling structural modules without complex built-in computers. Takeshi Ishida Copyright © 2015 Takeshi Ishida. All rights reserved. Effect of Bend Radius on Magnitude and Location of Erosion in S-Bend Thu, 01 Jan 2015 09:52:30 +0000 Solid particle erosion is a mechanical process that removes material by the impact of solid particles entrained in the flow. Erosion is a leading cause of failure of oil and gas pipelines and fittings in fluid handling industries. Different approaches have been used to control or minimize damage caused by erosion in particulated gas-solid or liquid-solid flows. S-bend geometry is widely used in different fluid handling equipment that may be susceptible to erosion damage. The results of a computational fluid dynamic (CFD) simulation of diluted gas-solid and liquid-solid flows in an S-bend are presented in this paper. In addition to particle impact velocity, the bend radius may have significant influence on the magnitude and the location of erosion. CFD analysis was performed at three different air velocities (15.24 m/s–45.72 m/s) and three different water velocities (0.1 m/s–10 m/s) with entrained solid particles. The particle sizes used in the analysis range between 50 and 300 microns. Maximum erosion was observed in water with 10 m/s, 250-micron particle size, and a ratio of 3.5. The location of maximum erosion was observed in water with 10 m/s, 300-micron particle size, and a ratio of 3.5. Comparison of CFD results with available literature data showed reasonable and good agreement. Quamrul H. Mazumder, Siwen Zhao, and Kawshik Ahmed Copyright © 2015 Quamrul H. Mazumder et al. All rights reserved. Practical Benefits of Aspect-Oriented Programming Paradigm in Discrete Event Simulation Sun, 28 Dec 2014 08:00:53 +0000 Aspect-oriented modeling and simulation is a new approach which uses the separation of concerns principle to enhance the quality of models and simulation tools. It adopts the separation of concerns (SOC) principle. Thus, crosscutting concerns such as processes synchronization, steady state detection, and graphical animation could be separated from simulation functional modules. The capture of crosscutting concerns in a modular way is carried out to cope with complexity and to achieve the required engineering quality factors such as robustness, modularity, adaptability, and reusability. This paper provides a summary of aspect-oriented paradigm with its usage in simulation by illustrating the main crosscutting concerns that may infect simulation systems. A practical example is given with the use of the Japrosim discrete event simulation library. Meriem Chibani, Brahim Belattar, and Abdelhabib Bourouis Copyright © 2014 Meriem Chibani et al. All rights reserved. Simulated Annealing Technique for Routing in a Rectangular Mesh Network Mon, 22 Dec 2014 07:38:49 +0000 In the process of automatic design for printed circuit boards (PCBs), the phase following cell placement is routing. On the other hand, routing process is a notoriously difficult problem, and even the simplest routing problem which consists of a set of two-pin nets is known to be NP-complete. In this research, our routing region is first tessellated into a uniform array of square cells. The ultimate goal for a routing problem is to achieve complete automatic routing with minimal need for any manual intervention. Therefore, shortest path for all connections needs to be established. While classical Dijkstra’s algorithm guarantees to find shortest path for a single net, each routed net will form obstacles for later paths. This will add complexities to route later nets and make its routing longer than the optimal path or sometimes impossible to complete. Today’s sequential routing often applies heuristic method to further refine the solution. Through this process, all nets will be rerouted in different order to improve the quality of routing. Because of this, we are motivated to apply simulated annealing, one of the metaheuristic methods to our routing model to produce better candidates of sequence. Noraziah Adzhar and Shaharuddin Salleh Copyright © 2014 Noraziah Adzhar and Shaharuddin Salleh. All rights reserved. A Simulation Model for Machine Efficiency Improvement Using Reliability Centered Maintenance: Case Study of Semiconductor Factory Sun, 30 Nov 2014 09:03:13 +0000 The purpose of this study was to increase the quality of product by focusing on the machine efficiency improvement. The principle of the reliability centered maintenance (RCM) was applied to increase the machine reliability. The objective was to create preventive maintenance plan under reliability centered maintenance method and to reduce defects. The study target was set to reduce the Lead PPM for a test machine by simulating the proposed preventive maintenance plan. The simulation optimization approach based on evolutionary algorithms was employed for the preventive maintenance technique selection process to select the PM interval that gave the best total cost and Lead PPM values. The research methodology includes procedures such as following the priority of critical components in test machine, analyzing the damage and risk level by using Failure Mode and Effects Analysis (FMEA), calculating the suitable replacement period through reliability estimation, and optimizing the preventive maintenance plan. From the result of the study it is shown that the Lead PPM of test machine can be reduced. The cost of preventive maintenance, cost of good product, and cost of lost product were decreased. Srisawat Supsomboon and Kanthapong Hongthanapach Copyright © 2014 Srisawat Supsomboon and Kanthapong Hongthanapach. All rights reserved. The Impact of Microstructure Geometry on the Mass Transport in Artificial Pores: A Numerical Approach Mon, 24 Nov 2014 10:10:47 +0000 The microstructure of porous materials used in heterogeneous catalysis determines the mass transport inside networks, which may vary over many length scales. The theoretical prediction of mass transport phenomena in porous materials, however, is incomplete and is still not completely understood. Therefore, experimental data for every specific porous system is needed. One possible experimental technique for characterizing the mass transport in such pore networks is pulse experiments. The general evaluation of experimental outcomes of these techniques follows the solution of Fick’s second law where an integral and effective diffusion coefficient is recognized. However, a detailed local understanding of diffusion and sorption processes remains a challenge. As there is lack of proved models covering different length scales, existing classical concepts need to be evaluated with respect to their ability to reflect local geometries on the nanometer level. In this study, DSMC (Direct Simulation Monte Carlo) models were used to investigate the impact of pore microstructures on the diffusion behaviour of gases. It can be understood as a virtual pulse experiment within a single pore or a combination of different pore geometries. Matthias Galinsky, Ulf Sénéchal, and Cornelia Breitkopf Copyright © 2014 Matthias Galinsky et al. All rights reserved. Event-Related Potentials Related to Anxiety in Emotion-Attention Interaction Wed, 08 Oct 2014 00:00:00 +0000 To identify neurological characteristics in accordance with anxiety under the interaction between emotion and attention, this study examines major ERP components when participants identify a target number by inhibiting task-irrelevant emotional face distractors. Experiments were conducted once per day at the same time for two days with 19 healthy adult men and women as required to study emotion-attention interaction. In this study, a variety of ERP components such as P100, N200, and P300 during experiment are significant. The amplitude and latency of the N200 component reflect both state and trait anxiety at all positions. This characteristic specially is prominently featured at Cz. Also, the latency of the late P300 component reflects the trait anxiety rather than state anxiety. The result of this study can help our understanding of the neurological responses related to anxiety during attentional control. Ssanghee Seo and Bonghyun Kim Copyright © 2014 Ssanghee Seo and Bonghyun Kim. All rights reserved. Runtime Instrumentation of SystemC/TLM2 Interfaces for Fault Tolerance Requirements Verification in Software Cosimulation Tue, 23 Sep 2014 08:21:09 +0000 This paper presents the design of a SystemC transaction level modelling wrapping library that can be used for the assertion of system properties, protocol compliance, or fault injection. The library uses C++ virtual table hooks as a dynamic binary instrumentation technique to inline wrappers in the TLM2 transaction path. This technique can be applied after the elaboration phase and needs neither source code modifications nor recompilation of the top level SystemC modules. The proposed technique has been successfully applied to the robustness verification of the on-board boot software of the Instrument Control Unit of the Solar Orbiter’s Energetic Particle Detector. Antonio da Silva, Pablo Parra, Óscar R. Polo, and Sebastián Sánchez Copyright © 2014 Antonio da Silva et al. All rights reserved. Achieving Fair Spectrum Allocation and Reduced Spectrum Handoff in Wireless Sensor Networks: Modeling via Biobjective Optimization Wed, 03 Sep 2014 05:48:56 +0000 This paper considers the problem of centralized spectrum allocations in wireless sensor networks towards the following goals: (1) maximizing fairness, (2) reflecting the priority among sensor data, and (3) avoiding unnecessary spectrum handoff. We cast this problem into a multiobjective mixed integer nonconvex nonlinear programming that is definitely difficult to solve at least globally without any aid of conversion or approximation. To tackle this intractability, we first convexify the original problem using arithmetic-geometric mean approximation and logarithmic change of the decision variables and then deploy weighted Chebyshev norm-based scalarization method in order to collapse the multiobjective problem into a single objective one. Finally, we apply simple rounding method in order to obtain approximate integer solutions. The results obtained from the numerical experiments show that, by adjusting the weight on each objective function, the proposed algorithm allocates spectrum bands fairly with well observing each sensor’s priority and reduced spectrum handoffs. Sang-Seon Byun, Kimmo Kansanen, Ilangko Balasingham, and Joon-Min Gil Copyright © 2014 Sang-Seon Byun et al. All rights reserved. Robust Inventory System Optimization Based on Simulation and Multiple Criteria Decision Making Tue, 02 Sep 2014 11:32:35 +0000 Inventory management in retailers is difficult and complex decision making process which is related to the conflict criteria, also existence of cyclic changes and trend in demand is inevitable in many industries. In this paper, simulation modeling is considered as efficient tool for modeling of retailer multiproduct inventory system. For simulation model optimization, a novel multicriteria and robust surrogate model is designed based on multiple attribute decision making (MADM) method, design of experiments (DOE), and principal component analysis (PCA). This approach as a main contribution of this paper, provides a framework for robust multiple criteria decision making under uncertainty. Ahmad Mortazavi and Alireza Arshadi khamseh Copyright © 2014 Ahmad Mortazavi and Alireza Arshadi khamseh. All rights reserved. Numerical Evaluation of a Light-Gas Gun Facility for Impact Test Tue, 19 Aug 2014 00:00:00 +0000 Experimental tests which match the application conditions might be used to properly evaluate materials for specific applications. High velocity impacts can be simulated using light-gas gun facilities, which come in different types and complexities. In this work different setups for a one-stage light-gas gun facility have been numerically analyzed in order to evaluate their suitability for testing materials and composites used as armor protection. A maximal barrel length of 6 m and a maximal reservoir pressure of a standard industrial gas bottle (20 MPa) were chosen as limitations. The numerical predictions show that it is not possible to accelerate the projectile directly to the desired velocity with nitrogen, helium, or hydrogen as propellant gas. When using a sabot corresponding to a higher bore diameter, the necessary velocity is achievable with helium and hydrogen gases. C. Rahner, H. A. Al-Qureshi, D. Stainer, D. Hotza, and M. C. Fredel Copyright © 2014 C. Rahner et al. All rights reserved. A Two-Stage Fuzzy Logic Control Method of Traffic Signal Based on Traffic Urgency Degree Mon, 04 Aug 2014 08:37:43 +0000 City intersection traffic signal control is an important method to improve the efficiency of road network and alleviate traffic congestion. This paper researches traffic signal fuzzy control method on a single intersection. A two-stage traffic signal control method based on traffic urgency degree is proposed according to two-stage fuzzy inference on single intersection. At the first stage, calculate traffic urgency degree for all red phases using traffic urgency evaluation module and select the red light phase with large traffic urgency as the next phase to switch. At the second stage, green delay of the current green phase is determined by fuzzy inference based on the amount of vehicles of current green phase and next green phase. The average vehicle delays are used to evaluate the performance of the fuzzy signal controller. Finally, comparisons have been made with pretimed controller and fuzzy logic controller without considering the urgency of red phase. Simulation results show the performance of our proposed method. Yan Ge Copyright © 2014 Yan Ge. All rights reserved. Computer Aided Modeling and Analysis of Five-Phase PMBLDC Motor Drive for Low Power High Torque Application Wed, 23 Jul 2014 13:44:26 +0000 In order to achieve high torque at low power with high efficiency, a new five-phase permanent magnet brushless DC (PMBLDC) motor design was analyzed and optimized. A similar three-phase motor having the same ratio (inner diameter () and length of the stator ()) is compared for maximum torque and torque ripple of the designed five-phase PMBLDC motor. Maxwell software was used to build finite element simulation model of the motor. The internal complicated magnetic field distribution and dynamic performance simulation were obtained in different positions. No load and load characteristics of the five-phase PMBLDC motor were simulated, and the power consumption of materials was computed. The conformity of the final simulation results indicates that this method can be used to provide a theoretical basis for further optimal design of this new type of motor with its drive so as to improve the starting torque and reduce torque ripple of the motor. M. A. Inayathullaah and R. Anita Copyright © 2014 M. A. Inayathullaah and R. Anita. All rights reserved. Schedulability Analysis for Rate Monotonic Algorithm-Shortest Job First Using UML-RT Wed, 23 Jul 2014 10:59:25 +0000 System modelling with a unified modelling language (UML) is an active research area for developing real-time system development. UML is widely used modelling language in software engineering community, to specify the requirement, and analyse the target system successfully. UML can be used to provide multiple views of the system under design with the help of a variety of structural and behavioural diagrams at an early stage. UML-RT (unified modelling language-real time) is a language used to build an unambiguous executable specification of a real-time system based on UML concepts. This paper presents a unified modeling approach for a newly proposed rate monotonic scheduling algorithm-shortest job first (RMA-SJF) for partitioned, semipartitioned and global scheduling strategies in multiprocessor architecture using UML-RT for different system loads. As a technical contribution, effective processor utilization of individual processors and success ratio are analyzed for various scheduling principles and compared with EDF and D_EDF to validate our proposal. S. Ewins Pon Pushpa and Manamalli Devasikamani Copyright © 2014 S. Ewins Pon Pushpa and Manamalli Devasikamani. All rights reserved. M/M/1 Multiple Vacation Queueing Systems with Differentiated Vacations Wed, 23 Jul 2014 00:00:00 +0000 We consider a multiple vacation queueing system in which a vacation following a busy period has a different distribution from a vacation that is taken without serving at least one customer. For ease of analysis it is assumed that the service times are exponentially distributed and the two vacation types are also exponentially distributed but with different means. The steady-state solution is obtained. Oliver C. Ibe and Olubukola A. Isijola Copyright © 2014 Oliver C. Ibe and Olubukola A. Isijola. All rights reserved. Estimation of Grain Orientation in an Anisotropic Weld by Using a Model of Ultrasonic Propagation in an Inverse Scheme Tue, 01 Jul 2014 13:36:20 +0000 The initial step towards a nondestructive technique that estimates grain orientation in an anisotropic weld is presented in this paper. The purpose is to aid future forward simulations of ultrasonic NDT of this kind of weld to achieve a better result. A forward model that consists of a weld model, a transmitter model, a receiver model, and a 2D ray tracing algorithm is introduced. An inversion based on a multiobjective genetic algorithm is also presented. Experiments are conducted for both P and SV waves in order to collect enough data used in the inversion. Calculation is conducted to fulfill the estimation with both the synthetic data and the experimental data. Concluding remarks are presented at the end of the paper. Qingwei Liu and Håkan Wirdelius Copyright © 2014 Qingwei Liu and Håkan Wirdelius. All rights reserved. Soil Saturated Simulation in Embankment during Strong Earthquake by Effect of Elasticity Modulus Tue, 01 Jul 2014 10:03:31 +0000 The dynamic analysis process was started after failure in some embankments during an earthquake. In this context, maximum displacement was reported at the crest based on interaction between structure and reservoir. This paper investigates the dynamic behavior of short embankment on soft soil. For this purpose, numerical analysis was carried out using ANSYS13 program based on finite-element method. Simulated models were vibrated by strong earthquake, so the peak ground acceleration (PGA) and duration were 0.65 g and 5.02 seconds, respectively. The comparison results were discussed in key points of plane strain analysis based on modulus ratio between saturated embankment and foundation. As concluded, the modulus ratio between 0.53 and 0.66 led to having a minimum value of horizontal displacement, relative displacement in vertical direction, and shear stress. Consequently, the shear stress was increased while the modulus ratio was decreased. Finally, to avoid more rigidity in the embankment on the soft soil, optimum modulus ratio was recommended at 0.66 in order to reduce the probabilistic of body cracks at the crest with respect to homogeneous behavior during an earthquake. Behrouz Gordan, Azlan Adnan, and Mariyana A. K. Aida Copyright © 2014 Behrouz Gordan et al. All rights reserved. A Simple Procedure for Searching Pareto Optimal Front in Machining Process: Electric Discharge Machining Thu, 26 Jun 2014 13:19:28 +0000 Optimum control parameter setting in complex and stochastic type processes is one of the most challenging problems to the process engineers. As such, effective model development and determination of optimal operating conditions of electric discharge machining process (EDM) are reasonably difficult. In this apper, an easy to handle optimization procedure, weight-varying multiobjective simulated annealing, is proposed and is applied to optimize two conflicting type response parameters in EDM—material removal rate (MRR) and average surface roughness (Ra) simultaneously. A solution set is generated. The Pareto optimal front thus developed is further modeled. An inverse solution procedure is devised so that near-optimum process parameter settings can be determined for specific need based requirements of process engineers. The results are validated. Ushasta Aich and Simul Banerjee Copyright © 2014 Ushasta Aich and Simul Banerjee. All rights reserved. Dynamic Modeling and Simulation of a Thermoelectric-Solar Hybrid Energy System Using an Inverse Dynamic Analysis Input Shaper Tue, 24 Jun 2014 12:55:56 +0000 This study presents the behavioral model of thermal temperature and power generation of a thermoelectric-solar hybrid energy system exposed to dynamic transient sources. In the development of thermoelectric-solar hybrid energy system, studies have focused on the regulation of both systems separately. In practice, a separate control system affects hardware pricing. In this study, an inverse dynamic analysis shaping technique based on exponential function is applied to a solar array (SA) to stabilize output voltage before this technique is combined with a thermoelectric module (TEM). This method can be used to estimate the maximum power point of the hybrid system by initially shaping the input voltage of SA. The behavior of the overall system can be estimated by controlling the behavior of SA, such that SA can follow the output voltage of TEM as the time constant of TEM is greater than that of SA. Moreover, by employing a continuous and differentiable function, the acquired output behavior of the hybrid system can be attained. Data showing the model is obtained from current experiments with predicted values of temperature, internal resistance, and current attributes of TEM. The simulation results show that the proposed input shaper can be used to trigger the output voltage of SA to follow the TEM behavior under transient conditions. A. M. Yusop, R. Mohamed, A. Ayob, and A. Mohamed Copyright © 2014 A. M. Yusop et al. All rights reserved. Instantaneous Power Theory with Fourier and Optimal Predictive Controller Design for Shunt Active Power Filter Tue, 24 Jun 2014 06:18:43 +0000 This paper presents a novel harmonic identification algorithm of shunt active power filter for balanced and unbalanced three-phase systems based on the instantaneous power theory called instantaneous power theory with Fourier. Moreover, the optimal design of predictive current controller using an artificial intelligence technique called adaptive Tabu search is also proposed in the paper. These enhancements of the identification and current control parts are the aim of the good performance for shunt active power filter. The good results for harmonic mitigation using the proposed ideas in the paper are confirmed by the intensive simulation using SPS in SIMULINK. The simulation results show that the enhanced shunt active power filter can provide the minimum %THD (Total Harmonic Distortion) of source currents and unity power factor after compensation. In addition, the %THD also follows the IEEE Std.519-1992. Suksan Tiyarachakun, Kongpol Areerak, and Kongpan Areerak Copyright © 2014 Suksan Tiyarachakun et al. All rights reserved. Otsu Based Optimal Multilevel Image Thresholding Using Firefly Algorithm Sun, 15 Jun 2014 10:59:29 +0000 Histogram based multilevel thresholding approach is proposed using Brownian distribution (BD) guided firefly algorithm (FA). A bounded search technique is also presented to improve the optimization accuracy with lesser search iterations. Otsu’s between-class variance function is maximized to obtain optimal threshold level for gray scale images. The performances of the proposed algorithm are demonstrated by considering twelve benchmark images and are compared with the existing FA algorithms such as Lévy flight (LF) guided FA and random operator guided FA. The performance assessment comparison between the proposed and existing firefly algorithms is carried using prevailing parameters such as objective function, standard deviation, peak-to-signal ratio (PSNR), structural similarity (SSIM) index, and search time of CPU. The results show that BD guided FA provides better objective function, PSNR, and SSIM, whereas LF based FA provides faster convergence with relatively lower CPU time. N. Sri Madhava Raja, V. Rajinikanth, and K. Latha Copyright © 2014 N. Sri Madhava Raja et al. All rights reserved. Wind Turbine Placement Optimization by means of the Monte Carlo Simulation Method Mon, 09 Jun 2014 05:44:06 +0000 This paper defines a new procedure for optimising wind farm turbine placement by means of Monte Carlo simulation method. To verify the algorithm’s accuracy, an experimental wind farm was tested in a wind tunnel. On the basis of experimental measurements, the error on wind farm power output was less than 4%. The optimization maximises the energy production criterion; wind turbines’ ground positions were used as independent variables. Moreover, the mathematical model takes into account annual wind intensities and directions and wind turbine interaction. The optimization of a wind farm on a real site was carried out using measured wind data, dominant wind direction, and intensity data as inputs to run the Monte Carlo simulations. There were 30 turbines in the wind park, each rated at 20 kW. This choice was based on wind farm economics. The site was proportionally divided into 100 square cells, taking into account a minimum windward and crosswind distance between the turbines. The results highlight that the dominant wind intensity factor tends to overestimate the annual energy production by about 8%. Thus, the proposed method leads to a more precise annual energy evaluation and to a more optimal placement of the wind turbines. S. Brusca, R. Lanzafame, and M. Messina Copyright © 2014 S. Brusca et al. All rights reserved. An Iterated Local Search Algorithm for Estimating the Parameters of the Gamma/Gompertz Distribution Thu, 05 Jun 2014 08:56:47 +0000 Extensive research has been devoted to the estimation of the parameters of frequently used distributions. However, little attention has been paid to estimation of parameters of Gamma/Gompertz distribution, which is often encountered in customer lifetime and mortality risks distribution literature. This distribution has three parameters. In this paper, we proposed an algorithm for estimating the parameters of Gamma/Gompertz distribution based on maximum likelihood estimation method. Iterated local search (ILS) is proposed to maximize likelihood function. Finally, the proposed approach is computationally tested using some numerical examples and results are analyzed. Behrouz Afshar-Nadjafi Copyright © 2014 Behrouz Afshar-Nadjafi. All rights reserved. Online Detection of Change on Information Streams in Wireless Sensor Network Modeled Using Gaussian Distribution Sun, 01 Jun 2014 08:36:46 +0000 Wireless sensor network (WSN) is deployed to monitor certain physical quantities in a region. This monitoring problem could be stated as the problem of detecting a change in the parameters of a static or dynamic stochastic system. A moving window procedure is proposed to detect the systematic error, which occurs at an unknown time. It can detect the deviation in the mean of sensor measurements keeping variance as constant. The performance measures, such as the average run length (ARL) to detection delay and false alarms are computed for various window sizes. The performance comparison is done against traditional cumulative sum (CUSUM) method. The detection of change in mean using CUSUM is done with smaller delay compared to the proposed moving window detection procedure. In order to calculate CUSUM statistics, the number of measurements to keep in sensor memory increases with time. However, in the proposed moving window detection procedure, the number of stored measurements is limited by the size of the window. Therefore, it is advantageous to use the moving window procedure for change detection in sensor nodes that have very limited memory. A high probability of detection is achieved at the cost of larger window size and higher detection delay. However, we are able to achieve the maximum probability of detection even at a window size of 11. B. Victoria Jancee and S. Radha Copyright © 2014 B. Victoria Jancee and S. Radha. All rights reserved. Numerical Survey of Contaminant Transport and Self-Cleansing of Water in Nador Lagoon, Morocco Tue, 27 May 2014 11:27:04 +0000 Numerical simulations are presented of the flow hydrodynamics and hypothetical contaminant dispersion patterns in Nador Lagoon, a shallow lagoon with a barrier island situated on the coast of Morocco. It is found that the natural circulation forced by the tidal flow in the lagoon is greatly affected by the development of an artificial inlet in the barrier island. The case study demonstrates the potential use of modern computational hydraulics as a tool integrated in the decision support system designed to manage a lagoon ecosystem. E. M. Chaabelasri, A. Amahmouj, M. Jeyar, A. G. L. Borthwick, N. Salhi, and I. Elmahi Copyright © 2014 E. M. Chaabelasri et al. All rights reserved. On Counting and Embedding a Subclass of Height-Balanced Trees Mon, 26 May 2014 08:35:29 +0000 A height-balanced tree is a rooted binary tree in which, for every vertex , the difference in the heights of the subtrees rooted at the left and right child of (called the balance factor of ) is at most one. In this paper, we consider height-balanced trees in which the balance factor of every vertex beyond a level is . We prove that there are such trees and embed them into a generalized join of hypercubes. Indhumathi Raman Copyright © 2014 Indhumathi Raman. All rights reserved. Analytic Model of Microcantilevers as Low Frequency Generator Sun, 25 May 2014 07:00:42 +0000 Finite element method (FEM) based simulation has been carried out, and an analytic model of microcantilevers using piezoelectric excitations is proposed. The model is based on the type of the selected material and geometry of the structure. The investigations are carried out with rectangular microcantilevers using silicon as the substrate. The high frequency analytic signals are applied to the input piezoelectric electrodes, and the resultant signal generated at the output piezoelectric electrode is recorded and analyzed. The analysis of the results showed that the proposed system is capable of generating a low frequency signal. Two microcantilevers with different dimensional aspects are used, and the results verified the application of microcantilever array as a low frequency signal generator. Sandeep Arya, Saleem Khan, and Parveen Lehana Copyright © 2014 Sandeep Arya et al. All rights reserved.