Modelling and Simulation in Engineering https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Increased Melting Heat Transfer in the Latent Heat Energy Storage from the Tube-and-Shell Model to the Combine-and-Shell Model Sun, 17 Sep 2017 09:08:44 +0000 http://www.hindawi.com/journals/mse/2017/8574184/ The melting of paraffin in thermal storage tube-and-shell and combine-and-shell models was conducted with the numerical research aim of decreasing the charge time through changing the shape of the tube into combining form. The results discussed are temperature contour, liquid-solid interface contour, temperature distribution, liquid fraction, and the average Nusselt number. The results show that the charge time in the tube-and-shell model is 2000 s, while the combine-and-shell model is 1200 s, meaning an overall decrease in charge time in the combine-and-shell model by 40% when compared to that of the tube-and-shell model. Agus Dwi Korawan, Sudjito Soeparman, Widya Wijayanti, and Denny Widhiyanuriyawan Copyright © 2017 Agus Dwi Korawan et al. All rights reserved. A New Sparse Gauss-Hermite Cubature Rule Based on Relative-Weight-Ratios for Bearing-Ranging Target Tracking Mon, 11 Sep 2017 07:41:14 +0000 http://www.hindawi.com/journals/mse/2017/2783781/ A new sparse Gauss-Hermite cubature rule is designed to avoid dimension explosion caused by the traditional full tensor-product based Gauss-Hermite cubature rule. Although Smolyak’s quadrature rule can successfully generate sparse cubature points for high dimensional integral, it has a potential drawback that some cubature points generated by Smolyak’s rule have negative weights, which may result in instability for the computation. A relative-weight-ratio criterion based sparse Gauss-Hermite rule is presented in this paper, in which cubature points are kept symmetric in the input space and corresponding weights are guaranteed to be positive. The generation of the new sparse cubature points set is simple and meaningful for practice. The difference between our new sparse Gauss-Hermite cubature rule and other cubature rules is analysed. Simulation results show that, compared with Kalman filter with those types of full tensor-product based Gauss-Hermite rules, our new sparse Gauss-Hermite cubature rule based Kalman filter can lead to a substantially reduced number of cubature points, more stable computation capability, and maintaining the accuracy of integration at the same time. Lijun Peng, Xiaojun Duan, and Jubo Zhu Copyright © 2017 Lijun Peng et al. All rights reserved. Numerical Modelling of Tailings Dam Thermal-Seepage Regime Considering Phase Transitions Tue, 01 Aug 2017 10:18:17 +0000 http://www.hindawi.com/journals/mse/2017/7245413/ Statement of the Problem. The article describes the problem of combined thermal-seepage regime for earth dams and those operated in the permafrost conditions. This problem can be solved using the finite elements method based on the local variational formulation. Results. A thermal-seepage regime numerical model has been developed for the “dam-foundation” system in terms of the tailings dam. The effect of heat-and-mass transfer and liquid phase transition in soil interstices on the dam state is estimated. The study with subsequent consideration of these factors has been undertaken. Conclusions. The results of studying the temperature-filtration conditions of the structure based on the factors of heat-and-mass transfer and liquid phase transition have shown that the calculation results comply with the field data. Ignoring these factors or one of them distorts the real situation of the dam thermal-seepage conditions. Aniskin Nikolay Alekseevich and Antonov Anton Sergeevich Copyright © 2017 Aniskin Nikolay Alekseevich and Antonov Anton Sergeevich. All rights reserved. A New Generalization of the Lomax Distribution with Increasing, Decreasing, and Constant Failure Rate Wed, 19 Jul 2017 07:38:34 +0000 http://www.hindawi.com/journals/mse/2017/6043169/ Developing new compound distributions which are more flexible than the existing distributions have become the new trend in distribution theory. In this present study, the Lomax distribution was extended using the Gompertz family of distribution, its resulting densities and statistical properties were carefully derived, and the method of maximum likelihood estimation was proposed in estimating the model parameters. A simulation study to assess the performance of the parameters of Gompertz Lomax distribution was provided and an application to real life data was provided to assess the potentials of the newly derived distribution. Excerpt from the analysis indicates that the Gompertz Lomax distribution performed better than the Beta Lomax distribution, Weibull Lomax distribution, and Kumaraswamy Lomax distribution. Pelumi E. Oguntunde, Mundher A. Khaleel, Mohammed T. Ahmed, Adebowale O. Adejumo, and Oluwole A. Odetunmibi Copyright © 2017 Pelumi E. Oguntunde et al. All rights reserved. Synthesis of Spatially Correlated Earthquake Ground Motions Based on Hilbert Transform Thu, 06 Jul 2017 06:31:59 +0000 http://www.hindawi.com/journals/mse/2017/2614769/ A simplified method for synthesizing spatially correlated earthquake ground motions is developed based on Hilbert transform and a reference earthquake record. In this method, one reference earthquake record is treated as the original ground motion, based on a series of generated ground motions. This procedure uses the instantaneous amplitude and the instantaneous phase of the record obtained using Hilbert transform to achieve the nonstationarity of ground motion. To establish the coherency between generated ground motions, an incoherence model is employed to describe the relation between the instantaneous phase at the present station and the instantaneous phases at previous stations. This type of phase is defined as the instantaneous coherence phase. In addition, time lag is included in the instantaneous coherence phase to prescribe the wave passage effect. The proposed Hilbert-transform-based method is efficient and avoids cumbersome parameter estimations as well as other drawbacks involved in some traditional synthesizing methods. Applications of this method demonstrate that the generated ground motions are statistically analogous with the reference record. Erlei Yao, Yu Miao, and Guobo Wang Copyright © 2017 Erlei Yao et al. All rights reserved. Multipass Turning Operation Process Optimization Using Hybrid Genetic Simulated Annealing Algorithm Wed, 21 Jun 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/1940635/ For years, there has been increasing attention placed on the metal removal processes such as turning and milling operations; researchers from different areas focused on cutting conditions optimization. Cutting conditions optimization is a crucial step in Computer Aided Process Planning (CAPP); it aims to select optimal cutting parameters (such as cutting speed, feed rate, depth of cut, and number of passes) since these parameters affect production cost as well as production deadline. This paper deals with multipass turning operation optimization using a proposed Hybrid Genetic Simulated Annealing Algorithm (HSAGA). The SA-based local search is properly embedded into a GA search mechanism in order to move the GA away from being closed within local optima. The unit production cost is considered in this work as objective function to minimize under different practical and operational constraints. Taguchi method is then used to calibrate the parameters of proposed optimization approach. Finally, different results obtained by various optimization algorithms are compared to the obtained solution and the proposed hybrid evolutionary technique optimization has proved its effectiveness over other algorithms. Abdelouahhab Jabri, Abdellah El Barkany, and Ahmed El Khalfi Copyright © 2017 Abdelouahhab Jabri et al. All rights reserved. The Generalized Twist for the Torsion of Piezoelectric Cylinders Thu, 15 Jun 2017 10:12:15 +0000 http://www.hindawi.com/journals/mse/2017/3634520/ In the classical theory of elasticity, Truesdell proposed the following problem: for an isotropic linearly elastic cylinder subject to end tractions equipollent to a torque , define a functional on such that , for each , where is the set of all displacement fields that correspond to the solutions of the torsion problem and depends only on the cross-section and the elastic properties of the considered cylinder. This problem has been solved by Day. In the present paper Truesdell’s problem is extended to the case of piezoelastic, monoclinic, and nonhomogeneous right cylinders. István Ecsedi and Attila Baksa Copyright © 2017 István Ecsedi and Attila Baksa. All rights reserved. Fuel Costs Minimization on a Steel Billet Reheating Furnace Using Genetic Algorithms Wed, 07 Jun 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/2731902/ Metallurgy industries often use steel billets, at a proper temperature, to achieve the desired metallurgical, mechanical, and dimensional properties of manufactured products. Optimal operation of steel billet reheating furnaces requires the minimization of fuel consumption while maintaining a homogeneous material thermal soak. In this study, the operation of a reheating furnace is modeled as a nonlinear optimization problem with the goal of minimizing fuel cost while satisfying a desired discharge temperature. For this purpose, a genetic algorithms approach is developed. Computational simulation results show that it is possible to minimize costs for different charge temperatures and production rates using the implemented method. Additionally, practical results are validated with actual data, in a specific scenario, showing a reduction of 3.36% of fuel consumption. Harley S. O. Santos, Paulo E. M. Almeida, and Rodrigo T. N. Cardoso Copyright © 2017 Harley S. O. Santos et al. All rights reserved. Numerical Study on Turbulent Forced Convection and Heat Transfer Characteristic in a Circular Tube with V-Orifice Mon, 15 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/3816739/ Performance assessments on heat transfer, pressure loss, and thermal enhancement factor in the circular tube heat exchanger inserted with the V-orifices are investigated numerically. The influences of the blockage ratio, gap spacing ratio, and orifice arrangement are reported for turbulent regime, . The finite volume method and SIMPLE algorithm are selected to solve the present problem. The mechanisms on flow and heat transfer characteristics are described. The periodic concepts on flow and heat transfer are also studied. The numerical results show that the gap spacing ratio is main reason for the changes of the flow and heat transfer topologies. The gap distance helps to adjust the optimum point of the thermal performance, especially at high flow blockage ratio. In addition, the optimum thermal performance of the present system is around 2.25 at the lowest Reynolds number, . Withada Jedsadaratanachai and Amnart Boonloi Copyright © 2017 Withada Jedsadaratanachai and Amnart Boonloi. All rights reserved. Performance Evaluation and Optimal Management of Distance-Based Registration Using a Semi-Markov Process Wed, 10 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/1432586/ We consider the distance-based registration (DBR) which is a kind of dynamic location registration scheme in a mobile communication network. In the DBR, the location of a mobile station (MS) is updated when it enters a base station more than or equal to a specified distance away from the base station where the location registration for the MS was done last. In this study, we first investigate the existing performance-evaluation methods on the DBR with implicit registration (DBIR) presented to improve the performance of the DBR and point out some problems of the evaluation methods. We propose a new performance-evaluation method for the DBIR scheme using a semi-Markov process (SMP) which can resolve the controversial issues of the existing methods. The numerical results obtained with the proposed SMP model are compared with those from previous models. It is shown that the SMP model should be considered to get an accurate performance of the DBIR scheme. Jae Joon Suh, Kyeongtaek Kim, Hee-Seon Jang, and Jang Hyun Baek Copyright © 2017 Jae Joon Suh et al. All rights reserved. Pareto Optimization of a Half Car Passive Suspension Model Using a Novel Multiobjective Heat Transfer Search Algorithm Wed, 03 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/2034907/ Most of the modern multiobjective optimization algorithms are based on the search technique of genetic algorithms; however the search techniques of other recently developed metaheuristics are emerging topics among researchers. This paper proposes a novel multiobjective optimization algorithm named multiobjective heat transfer search (MOHTS) algorithm, which is based on the search technique of heat transfer search (HTS) algorithm. MOHTS employs the elitist nondominated sorting and crowding distance approach of an elitist based nondominated sorting genetic algorithm-II (NSGA-II) for obtaining different nondomination levels and to preserve the diversity among the optimal set of solutions, respectively. The capability in yielding a Pareto front as close as possible to the true Pareto front of MOHTS has been tested on the multiobjective optimization problem of the vehicle suspension design, which has a set of five second-order linear ordinary differential equations. Half car passive ride model with two different sets of five objectives is employed for optimizing the suspension parameters using MOHTS and NSGA-II. The optimization studies demonstrate that MOHTS achieves the better nondominated Pareto front with the widespread (diveresed) set of optimal solutions as compared to NSGA-II, and further the comparison of the extreme points of the obtained Pareto front reveals the dominance of MOHTS over NSGA-II, multiobjective uniform diversity genetic algorithm (MUGA), and combined PSO-GA based MOEA. Vimal Savsani, Vivek Patel, Bhargav Gadhvi, and Mohamed Tawhid Copyright © 2017 Vimal Savsani et al. All rights reserved. Numerical Modal Analysis of Vibrations in a Three-Phase Linear Switched Reluctance Actuator Tue, 18 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/3258376/ This paper addresses the problem of vibrations produced by switched reluctance actuators, focusing on the linear configuration of this type of machines, aiming at its characterization regarding the structural vibrations. The complexity of the mechanical system and the number of parts used put serious restrictions on the effectiveness of analytical approaches. We build the 3D model of the actuator and use finite element method (FEM) to find its natural frequencies. The focus is on frequencies within the range up to nearly 1.2 kHz which is considered relevant, based on preliminary simulations and experiments. Spectral analysis results of audio signals from experimental modal excitation are also shown and discussed. The obtained data support the characterization of the linear actuator regarding the excited modes, its vibration frequencies, and mode shapes, with high potential of excitation due to the regular operation regimes of the machine. The results reveal abundant modes and harmonics and the symmetry characteristics of the actuator, showing that the vibration modes can be excited for different configurations of the actuator. The identification of the most critical modes is of great significance for the actuator’s control strategies. This analysis also provides significant information to adopt solutions to reduce the vibrations at the design. José Salvado, Maria do Rosário Calado, António Espírito Santo, and Anna Guerman Copyright © 2017 José Salvado et al. All rights reserved. Enhancing the Performance of the Microwave Absorbing Materials by Using Dielectric Resonator Arrays Wed, 05 Apr 2017 06:14:20 +0000 http://www.hindawi.com/journals/mse/2017/3658247/ We present a technique for enhancing the performance of microwave absorbing materials in terms of weight, thickness, and bandwidth. The introduced technique is based on fabricating the microwave absorbing (MA) material in a structure comprised of an array of circular cylinder dielectric resonators (CDR) backed by a perfect electric conductor (PEC) ground plane. Numerical electromagnetic methods are employed to study the properties of the proposed MA array structures, where 3D full wave simulation using finite-element method is implemented. The obtained results show that the performance of the MA-CDR arrays significantly outperforms that of a flat layer composed of the same material and having equivalent thickness. A flat layer of MA material with thickness of 5 mm backed by perfect electric conductor (PEC) shows as low as  dB reflection loss (RL) peak and ~3 GHz 10-dB bandwidth, whereas an MA-CDR array, composed of the same MA material, of height of 4 mm can achieve as low as ~−50 dB RL peak and ~12 GHz 10-dB RL bandwidth. Omar H. Al-Zoubi and Hameed Naseem Copyright © 2017 Omar H. Al-Zoubi and Hameed Naseem. All rights reserved. 3D Numerical and Experimental Study on Paraffin Wax Melting in Thermal Storage for the Nozzle-and-Shell, Tube-and-Shell, and Reducer-and-Shell Models Tue, 04 Apr 2017 07:36:29 +0000 http://www.hindawi.com/journals/mse/2017/9590214/ Paraffin melting experienced in the nozzle-and-shell, tube-and-shell, and reducer-and-shell models in thermal storage with 3D numerical and experimental approach has been studied. The numerical study aims to evaluate the melting process and discover temperature distribution, liquid-solid interface, liquid fraction, and the average surface Nusselt number, while the aim of this experimental study is to determine the distribution of melting temperature. The comparison of temperature distribution between the numerical approach and experimental one indicates a good agreement. The comparison result between the three models shows that the melting process of the nozzle-and-shell model is the best, followed by tube-and-shell and reducer-and-shell models, successively. To finish the melting process, the time required is 6130 s for the nozzle-and-shell model, while tube-and-shell model requires 8210 s and reducer-and-shell model requires 12280 s. Agus Dwi Korawan, Sudjito Soeparman, Widya Wijayanti, and Denny Widhiyanuriyawan Copyright © 2017 Agus Dwi Korawan et al. All rights reserved. Modeling of Size Effects in Bending of Perforated Cosserat Plates Thu, 30 Mar 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/5246197/ This paper presents the numerical study of Cosserat elastic plate deformation based on the parametric theory of Cosserat plates, recently developed by the authors. The numerical results are obtained using the Finite Element Method used to solve the parametric system of 9 kinematic equations. We discuss the existence and uniqueness of the weak solution and the convergence of the proposed FEM. The Finite Element analysis of clamped Cosserat plates of different shapes under different loads is provided. We present the numerical validation of the proposed FEM by estimating the order of convergence, when comparing the main kinematic variables with an analytical solution. We also consider the numerical analysis of plates with circular holes. We show that the stress concentration factor around the hole is less than the classical value, and smaller holes exhibit less stress concentration as would be expected on the basis of the classical elasticity. Roman Kvasov and Lev Steinberg Copyright © 2017 Roman Kvasov and Lev Steinberg. All rights reserved. Service Oriented Integration of Distributed Heterogeneous IT Systems in Production Engineering Using Information Standards and Linked Data Sun, 19 Mar 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/9814179/ While design of production systems based on digital models brings benefits, the communication of models comes with challenges since models typically reside in a heterogeneous IT environment using different syntax and semantics. Coping with heterogeneity requires a smart integration strategy. One main paradigm to integrate data and IT systems is to deploy information standards. In particular, ISO 10303 STEP has been endorsed as a suitable standard to exchange a wide variety of product manufacturing data. One the other hand, service-oriented tool integration solutions are progressively adopted for the integration of data and IT-tools, especially with the emergence of Open Services for Lifecycle Collaboration whose focus is on the linking of data from heterogeneous software tools. In practice, there should be a combination of these approaches to facilitate the integration process. Hence, the aim of this paper is to investigate the applications of the approaches and the principles behind them and try to find criteria for where to use which approach. In addition, we explore the synergy between them and consequently suggest an approach based on combination of them. In addition, a systematic approach is suggested to identify required level of integrations and their corresponding approaches exemplified in a typical IT system architecture in Production Engineering. Navid Shariat Zadeh, Lars Lindberg, Jad El-Khoury, and Gunilla Sivard Copyright © 2017 Navid Shariat Zadeh et al. All rights reserved. Identification and Prioritization of “Black Spots” without Using Accident Information Wed, 15 Mar 2017 07:50:44 +0000 http://www.hindawi.com/journals/mse/2017/1832654/ It is attempted to identify and prioritize the accident prone points (black spots) in “Iraanshahr-Sarbaaz-Chabahar” road located in Baluchistan, Iran, without no use of accident data but rather using Analytic Hierarchy Process (AHP), which is the enhanced procedure of road safety audit technique. First, by surveying the whole route, all factors that could influence accidents in this road were specified; then the route was divided into eight sections; this division was performed based on the uniformity and homogeny of each section in terms of geometric design and regional conditions. In each section, potentially hazardous locations were identified and some questionnaires were prepared, which were filled by 5 road traffic experts familiar with the route; then the collected data were analyzed by Analytical Hierarchy Process (AHP) using Expert Choice Software and the black spots were identified and prioritized. Finally, these black spots were compared with the black spots that had been obtained by traffic police based on accident data. Mahmoudreza Keymanesh, Hasan Ziari, Samira Roudini, and Ali Nasrollahtabar Ahangar Copyright © 2017 Mahmoudreza Keymanesh et al. All rights reserved. Systematic Theoretical Analysis of Dual-Parameters Readout by a Novel -Type Passive Sensor Mon, 13 Mar 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/4938732/ This paper systematically studied the simultaneous measurement of two parameters by a -type passive sensor from the theoretical perspective. Based on the lumped circuit model of the typical -type passive dual-parameter sensor system, the influencing factors of the signal strength of the sensor as well as the influencing factors of signal crosstalk were both analyzed. It is found that the influencing factors of the readout signal strength of the sensor are mainly quality factors ( factors) of the tanks, coupling coefficients, and the resonant frequency interval of the two tanks. And the influencing factors of the signal crosstalk are mainly coupling coefficient between the sensor inductance coils and the resonant frequency interval of the two tanks. The specific influence behavior of corresponding influencing factors on the signal strength and crosstalk is illustrated by a series of curves from numerical results simulated by using MATLAB software. Additionally, a decoupling scheme for solving the crosstalk problem algorithmically was proposed and a corresponding function was derived out. Overall, the theoretical analysis conducted in this work can provide design guidelines for making the dual-parameter -type passive sensor useful in practical applications. Qiulin Tan, Yanjie Guo, Guozhu Wu, Tao Luo, Tanyong Wei, Sanmin Shen, Wendong Zhang, and Jijun Xiong Copyright © 2017 Qiulin Tan et al. All rights reserved. Model-Based Dependability Analysis of Physical Systems with Modelica Wed, 08 Mar 2017 09:58:43 +0000 http://www.hindawi.com/journals/mse/2017/1578043/ Modelica is an innovative, equation-based, and acausal language that allows modeling complex physical systems, which are made of mechanical, electrical, and electrotechnical components, and evaluates their design through simulation techniques. Unfortunately, the increasing complexity and accuracy of such physical systems require new, more powerful, and flexible tools and techniques for evaluating important system properties and, in particular, the dependability ones such as reliability, safety, and maintainability. In this context, the paper describes some extensions of the Modelica language to support the modeling of system requirements and their relationships. Such extensions enable the requirement verification analysis through native constructs in the Modelica language. Furthermore, they allow exporting a Modelica-based system design as a Bayesian Network in order to analyze its dependability by employing a probabilistic approach. The proposal is exemplified through a case study concerning the dependability analysis of a Tank System. Andrea Tundis, Lena Buffoni, Peter Fritzson, and Alfredo Garro Copyright © 2017 Andrea Tundis et al. All rights reserved. System Identification Based Proxy Model of a Reservoir under Water Injection Thu, 23 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/7645470/ Simulation of numerical reservoir models with thousands and millions of grid blocks may consume a significant amount of time and effort, even when high performance processors are used. In cases where the simulation runs are required for sensitivity analysis, dynamic control, and optimization, the act needs to be repeated several times by continuously changing parameters. This makes it even more time-consuming. Currently, proxy models that are based on response surface are being used to lessen the time required for running simulations during sensitivity analysis and optimization. Proxy models are lighter mathematical models that run faster and perform in place of heavier models that require large computations. Nevertheless, to acquire data for modeling and validation and develop the proxy model itself, hundreds of simulation runs are required. In this paper, a system identification based proxy model that requires only a single simulation run and a properly designed excitation signal was proposed and evaluated using a benchmark case study. The results show that, with proper design of excitation signal and proper selection of model structure, system identification based proxy models are found to be practical and efficient alternatives for mimicking the performance of numerical reservoir models. The resulting proxy models have potential applications for dynamic well control and optimization. Berihun M. Negash, Lemma D. Tufa, M. Ramasamy, and Mariyamni Bt. Awang Copyright © 2017 Berihun M. Negash et al. All rights reserved. Optimal Allocation of DG and DSTATCOM in Radial Distribution System Using Cuckoo Search Optimization Algorithm Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/2857926/ This paper proposes a new approach to determine the optimal location and sizing of Distributed Generation (DG) and Distribution STATic COMpensator (DSTATCOM) simultaneously in the distribution network. The objective function is formulated to minimize the total power losses of the system subjected to equality and inequality constraints. Loss sensitivity factor (LSF) and Voltage Stability Index (VSI) are used to predetermine the optimal location of DG and DSTATCOM, respectively. Recently developed nature-inspired cuckoo search algorithm (CSA) has been used to determine the optimal size of both DG and DSTATCOM. In the present work, five different cases have been considered during DG and DSTATCOM placement to access the performance of the proposed technique. To check the feasibility, the proposed method is tested on IEEE 12-bus, 34-bus, and 69-bus radial distribution system and the results were compared with other existing techniques. T. Yuvaraj, K. Ravi, and K. R. Devabalaji Copyright © 2017 T. Yuvaraj et al. All rights reserved. Modelling of Rough Contact between Linear Viscoelastic Materials Wed, 15 Feb 2017 13:19:30 +0000 http://www.hindawi.com/journals/mse/2017/2521903/ The important gradients of stress arising in rough mechanical contacts due to interaction at the asperity level are responsible for damage mechanisms like rolling contact fatigue, wear, or crack propagation. The deterministic approach to this process requires computationally effective numerical solutions, capable of handling very fine meshes that capture the particular features of the investigated contacting surface. The spatial discretization needs to be supported by temporal sampling of the simulation window when time-dependent viscoelastic constitutive laws are considered in the description of the material response. Moreover, when real surface microtopography is considered, steep slopes inevitably lead to localized plastic deformation at the tip of the asperities that are first brought into contact. A computer model for the rough contact of linear viscoelastic materials, capable of handling deterministic contact geometry, complex viscoelastic models, and arbitrary loading histories, is advanced in this paper. Plasticity is considered in a simplified manner that preserves the information regarding the contact area and the pressure distribution without computing the residual strains and stresses. The model is expected to predict the contact behavior of deterministic rough surfaces as resulting from practical engineering applications, thus assisting the design of durable machine elements using elastomers or rubbers. Sergiu Spinu and Delia Cerlinca Copyright © 2017 Sergiu Spinu and Delia Cerlinca. All rights reserved. Analytical Modelling and Verification of Bus-Clamping Modulation Technique for Switched-Capacitor Converter Wed, 08 Feb 2017 06:08:21 +0000 http://www.hindawi.com/journals/mse/2017/6261404/ Space vector modulation techniques have advantages of high output voltages and reduced harmonic content as they utilize the dc bus effectively. Bus-clamped pulse width modulation classified in space vector techniques has the ability to reduce the switching losses of the converter and has reduced harmonic distortion. This paper provides mathematical analysis for 60-degree bus-clamping strategy to obtain the complete closed-form solution for finding the harmonic coefficients using double Fourier integral expression. The effectiveness of the bus-clamped approach on switched capacitor based multilevel inverter has been shown with comparison to Sinusoidal PWM. The DSP controller TMS320F240 has been chosen for the real-time implementation of 60-degree bus-clamping modulation technique. Simulation and experimental results of the prototype are presented for RL load at different modulation indices showing the superiority of the configuration to cascaded multilevel inverter. Amarnath Yalavarthi and Akbar Ahmad Copyright © 2017 Amarnath Yalavarthi and Akbar Ahmad. All rights reserved. Application of a Microstructure-Based ISV Plasticity Damage Model to Study Penetration Mechanics of Metals and Validation through Penetration Study of Aluminum Sun, 29 Jan 2017 09:06:09 +0000 http://www.hindawi.com/journals/mse/2017/6189168/ A developed microstructure-based internal state variable (ISV) plasticity damage model is for the first time used for simulating penetration mechanics of aluminum to find out its penetration properties. The ISV damage model tries to explain the interplay between physics at different length scales that governs the failure and damage mechanisms of materials by linking the macroscopic failure and damage behavior of the materials with their micromechanical performance, such as void nucleation, growth, and coalescence. Within the continuum modeling framework, microstructural features of materials are represented using a set of ISVs, and rate equations are employed to depict damage history and evolution of the materials. For experimental calibration of this damage model, compression, tension, and torsion straining conditions are considered to distinguish damage evolutions under different stress states. To demonstrate the reliability of the presented ISV model, that model is applied for studying penetration mechanics of aluminum and the numerical results are validated by comparing with simulation results yielded from the Johnson-Cook model as well as analytical results calculated from an existing theoretical model. Yangqing Dou, Yucheng Liu, Youssef Hammi, and Wilburn Whittington Copyright © 2017 Yangqing Dou et al. All rights reserved. Autotuning of Isotropic Hardening Constitutive Models on Real Steel Buckling Data with Finite Element Based Multistart Global Optimisation on Parallel Computers Mon, 16 Jan 2017 07:08:37 +0000 http://www.hindawi.com/journals/mse/2017/6132106/ An automatic framework for tuning plastic constitutive models is proposed. It is based on multistart global optimisation method, where the objective function is provided by the results of multiple elastoplastic finite element analyses, executed concurrently. Wrapper scripts were developed for fully automatic preprocessing, including model and mesh generation, analysis, and postprocessing. The framework is applied to an isotropic power hardening plasticity using real load/displacement data from multiple steel buckling tests. M. J. D. Powell’s BOBYQA constrained optimisation package was used for local optimisation. It is shown that using the real data presents multiple problems to the optimisation process because the objective function can be discontinuous, yet relatively flat around multiple local minima, with similar values of the objective function for different local minima. As a consequence the estimate of the global minimum is sensitive to the amount of experimental data and experimental noise. The framework includes the verification step, where the estimate of the global minimum is verified on a different geometry and loading. A tensile test was used for verification in this work. The speed of the method critically depends on the ability to effectively parallelise the finite element solver. Three levels of parallelisation were exploited in this work. The ultimate limitation was the availability of the finite element commercial solver license tokens. Anton Shterenlikht, Mohammad M. Kashani, Nicholas A. Alexander, Gethin Williams, and Adam J. Crewe Copyright © 2017 Anton Shterenlikht et al. All rights reserved. Structural Modelling at the Micro-, Meso-, and Nanoscales Tue, 10 Jan 2017 06:49:50 +0000 http://www.hindawi.com/journals/mse/2017/3504949/ Angelo Marcello Tarantino, Julius Kaplunov, Raimondo Luciano, Carmelo Majorana, Theodoros C. Rousakis, and Kasper Willam Copyright © 2017 Angelo Marcello Tarantino et al. All rights reserved. Fault Diagnosis and Detection in Industrial Motor Network Environment Using Knowledge-Level Modelling Technique Mon, 09 Jan 2017 11:43:15 +0000 http://www.hindawi.com/journals/mse/2017/1292190/ In this paper, broken rotor bar (BRB) fault is investigated by utilizing the Motor Current Signature Analysis (MCSA) method. In industrial environment, induction motor is very symmetrical, and it may have obvious electrical signal components at different fault frequencies due to their manufacturing errors, inappropriate motor installation, and other influencing factors. The misalignment experiments revealed that improper motor installation could lead to an unexpected frequency peak, which will affect the motor fault diagnosis process. Furthermore, manufacturing and operating noisy environment could also disturb the motor fault diagnosis process. This paper presents efficient supervised Artificial Neural Network (ANN) learning technique that is able to identify fault type when situation of diagnosis is uncertain. Significant features are taken out from the electric current which are based on the different frequency points and associated amplitude values with fault type. The simulation results showed that the proposed technique was able to diagnose the target fault type. The ANN architecture worked well with selecting of significant number of feature data sets. It seemed that, to the results, accuracy in fault detection with features vector has been achieved through classification performance and confusion error percentage is acceptable between healthy and faulty condition of motor. Saud Altaf, Muhammad Waseem Soomro, and Mirza Sajid Mehmood Copyright © 2017 Saud Altaf et al. All rights reserved. A Fast Enhanced Secure Image Chaotic Cryptosystem Based on Hybrid Chaotic Magic Transform Wed, 04 Jan 2017 12:29:33 +0000 http://www.hindawi.com/journals/mse/2017/7470204/ An enhanced secure image chaotic cryptosystem has been proposed based on hybrid CMT-Lanczos algorithm. We have achieved fast encryption and decryption along with privacy of images. The pseudorandom generator has been used along with Lanczos algorithm to generate root characteristics and eigenvectors. Using hybrid CMT image, pixels are shuffled to accomplish excellent randomness. Compared with existing methods, the proposed method had more robustness to various attacks: brute-force attack, known cipher plaintext, chosen-plaintext, security key space, key sensitivity, correlation analysis and information entropy, and differential attacks. Simulation results show that the proposed methods give better result in protecting images with low-time complexity. Srinivas Koppu and V. Madhu Viswanatham Copyright © 2017 Srinivas Koppu and V. Madhu Viswanatham. All rights reserved. Numerical Simulation of Magnetic Field Effect on Cryocooler Regenerators: Temperature Distribution Tue, 03 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/mse/2017/6171303/ Regenerative types of cryogenic refrigerators (or cryocoolers) employ magnetic intermetallic compounds of 3d and 4f elements to work well below 10 K. This paper presents the analysis of temperature distribution in regenerators of such cryocoolers under the influence of magnetic fields of 1 T, 3 T, and 4.3 T. Commercial code of finite element analysis (FEA) package, ANSYS (APDL) 14.5, is used to investigate the temperature distribution under above-mentioned fields. is selected as regenerator material and the criteria for its selection are discussed in detail. The cold end temperature is varied from 4.2 K to 10 K and hot end temperature is fixed at 20 K. The values obtained from FEA clearly show that the ineffectiveness of is at 8 K and 10 K at 3 T and 4.3 T. Rajendra Kumar and Sumit Shoor Copyright © 2017 Rajendra Kumar and Sumit Shoor. All rights reserved. On Torsion of Functionally Graded Elastic Beams Wed, 28 Dec 2016 10:16:09 +0000 http://www.hindawi.com/journals/mse/2016/8464205/ The evaluation of tangential stress fields in linearly elastic orthotropic Saint-Venant beams under torsion is based on the solution of Neumann and Dirichlet boundary value problems for the cross-sectional warping and for Prandtl stress function, respectively. A skillful solution method has been recently proposed by Ecsedi for a class of inhomogeneous beams with shear moduli defined in terms of Prandtl stress function of corresponding homogeneous beams. An alternative reasoning is followed in the present paper for orthotropic functionally graded beams with shear moduli tensors defined in terms of the stress function and of the elasticity of reference inhomogeneous beams. An innovative result of invariance on twist centre is also contributed. Examples of functionally graded elliptic cross sections of orthotropic beams are developed, detecting thus new benchmarks for computational mechanics. Marina Diaco Copyright © 2016 Marina Diaco. All rights reserved.