Journal of Computational Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Heat and Mass Transfer in the Boundary Layer of Unsteady Viscous Nanofluid along a Vertical Stretching Sheet Thu, 18 Dec 2014 11:52:42 +0000 Heat and mass transfer in the boundary-layer flow of unsteady viscous nanofluid along a vertical stretching sheet in the presence of magnetic field, thermal radiation, heat generation, and chemical reaction are presented in this paper. The sheet is situated in the xz-plane and y is normal to the surface directing towards the positive y-axis. The sheet is continuously stretching in the positive x-axis and the external magnetic field is applied to the system parallel to the positive y-axis. With the help of similarity transformations, the partial differential equations are transformed into a couple of nonlinear ordinary differential equations. The new problem is then solved numerically by a finite-difference scheme known as the Keller-box method. Effects of the necessary parameters in the flow field are explicitly studied and briefly explained graphically and in tabular form. For the selected values of the pertinent parameters appearing in the governing equations, numerical results of velocity, temperature, concentration, skin friction coefficient, Nusselt number, and Sherwood number are obtained. The results are compared to the works of others (from previously published journals) and they are found in excellent agreement. Eshetu Haile and B. Shankar Copyright © 2014 Eshetu Haile and B. Shankar. All rights reserved. Numerical Study of the Generic Sports Utility Vehicle Design with a Drag Reduction Add-On Device Wed, 17 Dec 2014 12:11:31 +0000 CFD simulations using ANSYS FLUENT 6.3.26 have been performed on a generic SUV design and the settings are validated using the experimental results investigated by Khalighi. Moreover, an add-on inspired by the concept presented by Englar at GTRI for drag reduction has been designed and added to the generic SUV design. CFD results of add-on model and the basic SUV model have been compared for a number of aerodynamic parameters. Also drag coefficient, drag force, mean surface pressure, mean velocities, and Cp values at different locations in the wake have been compared for both models. The main objective of the study is to present a new add-on device which may be used on SUVs for increasing the fuel efficiency of the vehicle. Mean pressure results show an increase in the total base pressure on the SUV after using the device. An overall reduction of 8% in the aerodynamic drag coefficient on the add-on SUV has been investigated analytically in this study. Shubham Singh, M. Zunaid, Naushad Ahmad Ansari, Shikha Bahirani, Sumit Dhall, and Sandeep Kumar Copyright © 2014 Shubham Singh et al. All rights reserved. An Improved Unscented Particle Filter with Global Sampling Strategy Wed, 10 Dec 2014 00:10:23 +0000 Particle filter (PF) has many variations and one of the most popular is the unscented particle filter (UPF). UPF uses the unscented Kalman filter (UKF) to generate particles in the PF framework and has a better performance than the standard PF. However, UPF suffers from its high computation complexity because it has to execute UKF to each particle to obtain proposal distribution. This paper gives an improved UPF aiming at reducing the computation complexity of the algorithm. In comparison to the standard UPF, the new strategy generates proposal distribution from the mean and covariance value of the whole particles instead of from each particle. Thus the improved algorithm utilizes the characteristics of the whole particles and only needs to perform UKF algorithm once to get the proposal distribution at each time step. Experimental results show that, compared to standard UPF, the improved algorithm reduces the time consumption greatly almost without performance degradation. Yi-zheng Zhao Copyright © 2014 Yi-zheng Zhao. All rights reserved. FDTD Acceleration for Cylindrical Resonator Design Based on the Hybrid of Single and Double Precision Floating-Point Computation Thu, 04 Dec 2014 07:52:22 +0000 Acceleration of FDTD (finite-difference time-domain) is very important for the fields such as computational electromagnetic simulation. We consider the FDTD simulation model of cylindrical resonator design that requires double precision floating-point and cannot be done using single precision. Conventional FDTD acceleration methods have a common problem of memory-bandwidth limitation due to the large amount of parallel data access. To overcome this problem, we propose a hybrid of single and double precision floating-point computation method that reduces the data-transfer amount. We analyze the characteristics of the FDTD simulation to find out when we can use single precision instead of double precision. According to the experimental results, we achieved over 15 times of speed-up compared to the CPU single-core implementation and over 1.52 times of speed-up compared to the conventional GPU-based implementation. Hasitha Muthumala Waidyasooriya, Masanori Hariyama, Yasuhiro Takei, and Michitaka Kameyama Copyright © 2014 Hasitha Muthumala Waidyasooriya et al. All rights reserved. Computational Modelling of the Structural Integrity following Mass-Loss in Polymeric Charred Cellular Solids Mon, 27 Oct 2014 07:17:56 +0000 A novel computational technique is presented for embedding mass-loss due to burning into the ANSYS finite element modelling code. The approaches employ a range of computational modelling methods in order to provide more complete theoretical treatment of thermoelasticity absent from the literature for over six decades. Techniques are employed to evaluate structural integrity (namely, elastic moduli, Poisson’s ratios, and compressive brittle strength) of honeycomb systems known to approximate three-dimensional cellular chars. That is, reducing the mass of diagonal ribs and both diagonal-plus-vertical ribs simultaneously show rapid decreases in the structural integrity of both conventional and reentrant (auxetic, i.e., possessing a negative Poisson’s ratio) honeycombs. On the other hand, reducing only the vertical ribs shows initially modest reductions in such properties, followed by catastrophic failure of the material system. Calculations of thermal stress distributions indicate that in all cases the total stress is reduced in reentrant (auxetic) cellular solids. This indicates that conventional cellular solids are expected to fail before their auxetic counterparts. Furthermore, both analytical and FE modelling predictions of the brittle crush strength of both auxteic and conventional cellular solids show a relationship with structural stiffness. J. P. M. Whitty, J. Francis, J. Howe, and B. Henderson Copyright © 2014 J. P. M. Whitty et al. All rights reserved. Sinc Collocation Method for Finding Numerical Solution of Integrodifferential Model Arisen in Continuous Mixed Strategy Wed, 17 Sep 2014 00:00:00 +0000 One of the new techniques is used to solve numerical problems involving integral equations and ordinary differential equations known as Sinc collocation methods. This method has been shown to be an efficient numerical tool for finding solution. The construction mixed strategies evolutionary game can be transformed to an integrodifferential problem. Properties of the sinc procedure are utilized to reduce the computation of this integrodifferential to some algebraic equations. The method is applied to a few test examples to illustrate the accuracy and implementation of the method. F. Hosseini Shekarabi Copyright © 2014 F. Hosseini Shekarabi. All rights reserved. Ground to Cloud Lightning Flash Currents and Electric Fields: Interaction with Aircraft and Production of Ionosphere Sprites Sun, 03 Aug 2014 07:59:54 +0000 This paper presents for the first time a case for the importance of ground to cloud (upward leader) lightning flash parameters for safety testing of direct aircraft-lightning interaction and protection of wind turbines, as well as the importance of radiated electric fields for indirect lightning-aircraft interaction and generation of electric discharges called sprites and halos in the ionosphere. By using an electric circuit model of the transverse magnetic waves along the return stroke channel, electric currents at ground level as well as cloud level are determined for both the cloud to ground lightning flash and the ground to cloud lightning flash. We show that when an aircraft triggers lightning, the electric currents will be much more severe in current magnitude, rate of rise of currents, and frequency spectrum than otherwise and are more severe than the parameters observed for the usual and well monitored (and measured) cloud to ground (downward leader) flashes. The rate of rise of currents and the frequency spectrum of the ground to cloud lightning flash are also given here. The electric fields radiated by the lightning flashes that would appear in the ionosphere are presented for both the earth flash and the ground to cloud flash. P. R. P. Hoole, S. Thirukumaran, Harikrishnan Ramiah, Jeevan Kanesan, and S. R. H. Hoole Copyright © 2014 P. R. P. Hoole et al. All rights reserved. A Modified Homotopy Perturbation Transform Method for Transient Flow of a Third Grade Fluid in a Channel with Oscillating Motion on the Upper Wall Thu, 17 Jul 2014 06:27:44 +0000 A new analytical algorithm based on modified homotopy perturbation transform method is employed for solving the transient flow of third grade fluid in a porous channel generated by an oscillating upper wall. This method incorporates the He’s polynomial into the HPM, combined with Laplace transform. Comparison with HPM and OHAM analytical solutions reveals that the proposed algorithm is highly accurate. This proves the validity and great potential of the proposed algorithm as a new kind of powerful analytical tool for transient nonlinear problems. Graphs representing the solutions are discussed, and appropriate conclusions are drawn. Mohammed Abdulhameed, Rozaini Roslan, and Mahathir Bin Mohamad Copyright © 2014 Mohammed Abdulhameed et al. All rights reserved. Direct Numerical Simulation of Twin Swirling Flow Jets: Effect of Vortex-Vortex Interaction on Turbulence Modification Wed, 09 Jul 2014 08:55:32 +0000 A direct numerical simulation (DNS) was carried out to study twin swirling jets which are issued from two parallel nozzles at a Reynolds number of and three swirl levels of , 1.08, and 1.42, respectively. The basic structures of vortex-vortex interaction and temporal evolution are illustrated. The characteristics of axial variation of turbulent fluctuation velocities, in both the near and far field, in comparison to a single swirling jet, are shown to explore the effects of vortex-vortex interaction on turbulence modifications. Moreover, the second order turbulent fluctuations are also shown, by which the modification of turbulence associated with the coherent or correlated turbulent fluctuation and turbulent kinetic energy transport characteristics are clearly indicated. It is found that the twin swirling flow has a fairly strong localized vortex-vortex interaction between a pair of inversely rotated vortices. The location and strength of interaction depend on swirl level greatly. The modification of vortex takes place by transforming large-scale vortices into complex small ones, whereas the modulation of turbulent kinetic energy is continuously augmented by strong vortex modification. Wenkai Xu, Nan Gui, Liang Ge, and Jie Yan Copyright © 2014 Wenkai Xu et al. All rights reserved. Dynamic Analysis under Uniformly Distributed Moving Masses of Rectangular Plate with General Boundary Conditions Thu, 19 Jun 2014 09:13:36 +0000 The problem of the flexural vibrations of a rectangular plate having arbitrary supports at both ends is investigated. The solution technique which is suitable for all variants of classical boundary conditions involves using the generalized two-dimensional integral transform to reduce the fourth order partial differential equation governing the vibration of the plate to a second order ordinary differential equation which is then treated with the modified asymptotic method of Struble. The closed form solutions are obtained and numerical analyses in plotted curves are presented. It is also deduced that for the same natural frequency, the critical speed for the system traversed by uniformly distributed moving forces at constant speed is greater than that of the uniformly distributed moving mass problem for both clamped-clamped and simple-clamped end conditions. Hence resonance is reached earlier in the uniformly distributed moving mass system. Furthermore, for both structural parameters considered, the response amplitude of the moving distributed mass system is higher than that of the moving distributed force system. Thus, it is established that the moving distributed force solution is not an upper bound for an accurate solution of the moving distributed mass problem. Emem Ayankop Andi and Sunday Tunbosun Oni Copyright © 2014 Emem Ayankop Andi and Sunday Tunbosun Oni. All rights reserved. Natural Convection Flow along an Isothermal Vertical Flat Plate with Temperature Dependent Viscosity and Heat Generation Tue, 27 May 2014 12:42:51 +0000 The purpose of this study is to investigate the natural convection laminar flow along an isothermal vertical flat plate immersed in a fluid with viscosity which is the exponential function of fluid temperature in presence of internal heat generation. The governing boundary layer equations are transformed into a nondimensional form and the resulting nonlinear system of partial differential equations is reduced to a convenient form which are solved numerically using an efficient marching order implicit finite difference method with double sweep technique. Numerical results are presented in terms of the velocity and temperature distribution of the fluid as well as the heat transfer characteristics, namely, the wall shear stress and the local and average rate of heat transfer in terms of the local skin-friction coefficient, the local and average Nusselt number for a wide range of the viscosity-variation parameter, heat generation parameter, and the Rayleigh number. Increasing viscosity variation parameter and Rayleigh number lead to increasing the local and average Nusselt number and decreasing the wall shear stress. Wall shear stress and the rate of heat transfer decreased due to the increase of heat generation. Md. Mamun Molla, Anita Biswas, Abdullah Al-Mamun, and Md. Anwar Hossain Copyright © 2014 Md. Mamun Molla et al. All rights reserved. Modal Spectral Element Solutions to Incompressible Flows over Particles of Complex Shape Wed, 30 Apr 2014 09:15:47 +0000 This paper develops the virtual identity particles (VIP) model to simulate two-phase flows involving complex-shaped particles. VIP assimilates the high efficiency of the Eulerian method and the convenience of the Lagrangian approach in tracking particles. It uses one fixed Eulerian mesh to compute the fluid field and the Lagrangian description to handle constitutive properties of particles. The interaction between the fluid and complex particles is characterized with source terms in the fluid momentum equations, while the same source terms are computed iteratively from the particulate Lagrangian equations. The advantage of VIP is its economy in modeling a two-phase flow problem almost at the cost of solving only the fluid phase with added source terms. This high efficiency in computational cost makes VIP viable for simulating particulate flows with numerous particles. Owing to the spectral convergence and high resolvability of the modal spectral element method, VIP provides acceptable resolution comparable to DNS but at much reduced computational cost. Simulation results indicate that VIP is promising for investigating flows with complex-shaped particles, especially abundant complex particles. Don Liu and Yonglai Zheng Copyright © 2014 Don Liu and Yonglai Zheng. All rights reserved. Data Dissemination Protocol for Mobile Sink in Wireless Sensor Networks Sun, 27 Apr 2014 11:58:46 +0000 In wireless sensor networks, the sensor nodes find the route towards the sink to transmit the data. The sensor node transmits the data directly to the sink, or it relays the data through neighbor nodes. The nodes near to the sink transmit more data than other nodes. It results in the small lifetime of the network. To prolong the lifetime of the network, we use the mobile sink approach. The mobile sink makes the network dynamic. It is a challenging task to find the route in the dynamic network. In this paper, we have proposed a distributed tree-based data dissemination (TEDD) protocol with mobile sink. The protocol is validated through simulation and compared with the existing protocols using some metrics such as energy consumption, average end-to-end delay, and throughput. The experiment results show that the proposed protocol outperforms the existing protocols. Suraj Sharma and Sanjay Kumar Jena Copyright © 2014 Suraj Sharma and Sanjay Kumar Jena. All rights reserved. Numerical Solutions of Fifth and Sixth Order Nonlinear Boundary Value Problems by Daftardar Jafari Method Sun, 30 Mar 2014 08:24:59 +0000 Fifth and sixth order boundary value problems are solved using Daftardar Jafari method (DJM). DJM is introduced by Daftardar-Gejji and Jafari (2006). The approach provides the solution in the form of a rapidly convergent series. The comparison among Daftardar Jafari method (DJM), Adomian decomposition method (ADM), homotopy perturbation method (HPM), variation iteration method (VIM), and the iterative method (ITM) are displayed in table form which shows the efficiency of DJM for the solution of fifth and sixth order BVPs. Inayat Ullah, Hamid Khan, and M. T. Rahim Copyright © 2014 Inayat Ullah et al. All rights reserved. Navier-Stokes Equation and Computational Scheme for Non-Newtonian Debris Flow Thu, 27 Mar 2014 09:08:49 +0000 This paper proposes a computational approach to debris flow model. In recent years, the theoretical activity on the classical Herschel-Bulkley model (1926) has been very intense, but it was in the early 80s that the opportunity to explore the computational model has enabled considerable progress in identifying the subclasses of applicability of different sets of boundary conditions and their approximations. Here we investigate analytically the problem of the simulation of uniform motion for heterogeneous debris flow laterally confined taking into account mainly the geological data and methodological suggestions derived from simulation with cellular automata and grid systems, in order to propose a computational scheme able to operate a compromise between “global” predictive capacities and computing effort. Ignazio Licata and Elmo Benedetto Copyright © 2014 Ignazio Licata and Elmo Benedetto. All rights reserved. Shape of Slender Axisymmetric Ventilated Supercavities Sun, 23 Mar 2014 09:31:30 +0000 The integral-differential equation was obtained to simulate unsteady evolutions of the slender axisymmetric ventilated supercavity with the use of one-dimensional inviscid flow of the incompressible gas in the channel between the cavity surface and the body of revolution. For small ventilation rates, the solution of this equation was expressed as asymptotic series. In the steady case the nonlinear differential equation and its solutions were obtained. It was shown that the ventilation can increase and diminish the supercavity dimensions. Examples of calculations for different hull shapes are presented. At some critical values of the gas injection rate the cavity dimensions can become unbounded. Stability of steady and pulsating gas cavities was investigated in the case of the low gas injection rate. Igor Nesteruk Copyright © 2014 Igor Nesteruk. All rights reserved. QoS-Aware Middleware for Ubiquitous Environment: A Review and Proposed Solution Wed, 19 Mar 2014 09:37:13 +0000 Ubiquitous computing has introduced a new era of computing. Compared to traditional distributed systems, ubiquitous computing systems feature increased dynamism and heterogeneity. In traditional computing environments (mainframe and PC), users actively choose to interact with computers. Ubiquitous computing applications are likely to be different, where computing systems are available anywhere but not visible. The underlying ubiquitous computing infrastructures are more complex and bring up many issues. In this work we survey the literature to demonstrate, in detail, the characteristics and the challenges of the ubiquitous computing as well as the requirements for building ubiquitous software that brings these characteristics into reality. Furthermore we present some existing middleware solutions for ubiquitous environments, and propose our middleware-based architecture to facilitate the user interaction in such environment. To the best of our knowledge this is the first work proposing DDS-based solution for ubiquitous computing as a unified middleware. Anas Al-Roubaiey and M. AL-Rhman Alkhiaty Copyright © 2014 Anas Al-Roubaiey and M. AL-Rhman Alkhiaty. All rights reserved. Solution of Axisymmetric Potential Problem in Oblate Spheroid Using the Exodus Method Mon, 17 Mar 2014 08:11:43 +0000 This paper presents the use of Exodus method for computing potential distribution within a conducting oblate spheroidal system. An explicit finite difference method for solving Laplace’s equation in oblate spheroidal coordinate systems for an axially symmetric geometry was developed. This was used to determine the transition probabilities for the Exodus method. A strategy was developed to overcome the singularity problems encountered in the oblate spheroid pole regions. The potential computation results obtained correlate with those obtained by exact solution and explicit finite difference methods. O. D. Momoh, M. N. O. Sadiku, and S. M. Musa Copyright © 2014 O. D. Momoh et al. All rights reserved. Combined Analytical-Numerical Solution for MHD Viscous Flow over a Stretching Sheet Thu, 13 Mar 2014 16:45:37 +0000 We studied the two-dimensional flow of viscous and electrically conducting fluid over a stretching sheet under the influence of constant magnetic field. Approximate analytical solution of governing nonlinear boundary layer equation via optimal homotopy asymptotic method (OHAM) is obtained. For numerical comparison we used Runge-Kutta-Fehlberg fourth-fifth-order method. The effect of different parameters on fluid flow is analyzed. It is found that the OHAM solution is very close to the numerical solution for different assigned values of parameters; this thus indicates the feasibility of the proposed method (OHAM). Fazle Mabood and Waqar A. Khan Copyright © 2014 Fazle Mabood and Waqar A. Khan. All rights reserved. A Comparative Study on Decision Making Methods with Interval Data Tue, 11 Mar 2014 14:50:59 +0000 Multiple Criteria Decision Making (MCDM) models are used to solve a number of decision making problems universally. Most of these methods require the use of integers as input data. However, there are problems which have indeterminate values or data intervals which need to be analysed. In order to solve problems with interval data, many methods have been reported. Through this study an attempt has been made to compare and analyse the popular decision making tools for interval data problems. Namely, I-TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), DI-TOPSIS, cross entropy, and interval VIKOR (VlseKriterijumska Optimiza-cija I Kompromisno Resenje) have been compared and a novel algorithm has been proposed. The new algorithm makes use of basic TOPSIS technique to overcome the limitations of known methods. To compare the effectiveness of the various methods, an example problem has been used where selection of best material family for the capacitor application has to be made. It was observed that the proposed algorithm is able to overcome the known limitations of the previous techniques. Thus, it can be easily and efficiently applied to various decision making problems with interval data. Aditya Chauhan and Rahul Vaish Copyright © 2014 Aditya Chauhan and Rahul Vaish. All rights reserved. Effects of Lateral Window Position and Wind Direction on Wind-Driven Natural Cross Ventilation of a Building: A Computational Approach Tue, 11 Mar 2014 09:18:55 +0000 Energy is saved when an effective natural ventilation system can provide comfort air to the occupants in a building by replacing a mechanical ventilation system. It also minimizes the risk of the environmental pollution and the global warming. A one story, full scale building was considered to carry out a comparative study of three different cases of wind-driven natural (WDN) cross ventilation with the help of computational fluid dynamics (CFD). In each case, the location of window was changed in lateral direction to predict the probable position for optimum ventilation performance and the angle of wind was varied to check the sensitivity of the wind direction on the flow field. After validating the current methodology through two satisfactory comparisons with the experimental investigations, the governing equations subjected to the corresponding boundary conditions were solved using commercial software and then the results were analyzed. A better location for the windows in each case was proposed. The ventilation purpose was served quite well even if the wind angle was changed in a moderate range from the original design. Furthermore, the velocity components, ventilation rate, surface pressure, ventilation time, and so forth in each case were investigated and compared extensively with those in other cases. M. Z. I. Bangalee, J. J. Miau, S. Y. Lin, and M. Ferdows Copyright © 2014 M. Z. I. Bangalee et al. All rights reserved. Computational Model for Internal Relative Humidity Distributions in Concrete Sun, 09 Mar 2014 09:08:53 +0000 A computational model is developed for predicting nonuniform internal relative humidity distribution in concrete. Internal relative humidity distribution is known to have a direct effect on the nonuniform drying shrinkage strains. These nonuniform drying shrinkage strains result in the buildup of internal stresses, which may lead to cracking of concrete. This may be particularly true at early ages of concrete since the concrete is relatively weak while the difference in internal relative humidity is probably high. The results obtained from this model can be used by structural and construction engineers to predict critical drying shrinkage stresses induced due to differential internal humidity distribution. The model uses finite elment-finite difference numerical methods. The finite element is used to space discretization while the finite difference is used to obtain transient solutions of the model. The numerical formulations are then programmed in Matlab. The numerical results were compared with experimental results found in the literature and demonstrated very good agreement. Wondwosen Ali and Girum Urgessa Copyright © 2014 Wondwosen Ali and Girum Urgessa. All rights reserved. Wavelet Method for Numerical Solution of Parabolic Equations Thu, 27 Feb 2014 16:43:10 +0000 We derive a highly accurate numerical method for the solution of parabolic partial differential equations in one space dimension using semidiscrete approximations. The space direction is discretized by wavelet-Galerkin method using some special types of basis functions obtained by integrating Daubechies functions which are compactly supported and differentiable. The time variable is discretized by using various classical finite difference schemes. Theoretical and numerical results are obtained for problems of diffusion, diffusion-reaction, convection-diffusion, and convection-diffusion-reaction with Dirichlet, mixed, and Neumann boundary conditions. The computed solutions are highly favourable as compared to the exact solutions. A. H. Choudhury Copyright © 2014 A. H. Choudhury. All rights reserved. Analysis of Parallel Multidimensional Wave Digital Filtering Network on IBM Cell Broadband Engine Mon, 17 Feb 2014 11:16:37 +0000 As an alternative approach for the numerical integration of physical systems, the MDWDF technique has become of importance in the field of numerical analysis due to its attractive features, for example, massive parallelism and high accuracy both inherent in nature. In this study, speed-up efficiencies of a MDWDF network are studied for the linearized shallow water system, which plays an important role in fluid dynamics. To achieve the goal, the full parallelism of the MDWDF network is established in the first place based on the chained MD retiming technique. Following the implementation on the IBM Cell Broadband Engine (Cell/BE), excellent performance of the full parallel architecture is revealed. The IBM Cell/BE containing 1 power processor element (PPE) and 8 synergistic processor elements (SPEs) perfectly fits the architecture of the retimed MDWDF model. Empirical results have demonstrated that the full parallelized model with 8 processors (1PPE + 7SPEs) outperforms the other three models: partial right/left-loop retimed models and the full sequential model with 4× improvements for scheduled grids . In addition, for scheduled fine grids , the full parallel model is shown to possess significant performance over these models by up to 7× improvements. Chien Hsun Tseng Copyright © 2014 Chien Hsun Tseng. All rights reserved. On the Validity of Flat-Plate Finite Strip Approximation of Circular Cylindrical Shells Tue, 11 Feb 2014 15:57:48 +0000 The validity of modeling curved shell panels using flat-plate finite strips has been demonstrated in the past by comparing finite strip numerical results with analytical solutions of a few benchmark problems; to date, no mathematical exact solutions of the method or its explicit forms of error terms have been rigorously derived to demonstrate analytically its validity. Using a unitary transformation approach (abbreviated as the U-transformation herein), an attempt is made in this paper to derive mathematical exact solutions of flat-plate finite strips in cylindrical shell vibration analysis. Unlike the conventional finite strip method which involves assembly of the global system of matrix equation and its numerical solution, the U-transformation method makes use of the inherent cyclic symmetry of cylindrical shells to decouple the global matrix equation into one involving only a few unknowns, thus rendering explicit form of solutions for the flat-shell finite strip to be derived. Such explicit solutions can be subsequently expanded into Taylor's series whose results reveal directly their convergence to the exact solutions and the corresponding rate of convergence. Jackson Kong Copyright © 2014 Jackson Kong. All rights reserved. Application of Wedges for the Reduction of the Space and Time-Dependent Harmonic Content in Squirrel-Cage Induction Motors Sun, 29 Dec 2013 10:35:58 +0000 The influence of the semimagnetic stator wedges of different sizes on the electromagnetic characteristics and the behavior of the induction motor is investigated. The study will be carried out with both analytical calculations and FEM analysis. The analytical calculations will take into account the stator and rotor slots, as well as the iron core saturation in order to study the spatial and time-dependent harmonic content of the air-gap magnetic flux density and electromagnetic torque. The size of the wedge plays an important role as it determines the tooth tips saturation, the high harmonic content of the air-gap magnetic flux density, and the electromagnetic characteristics of the induction motor. Konstantinos N. Gyftakis, Panagiotis A. Panagiotou, and Joya C. Kappatou Copyright © 2013 Konstantinos N. Gyftakis et al. All rights reserved. On Performance of Weighted Fusion Based Spectrum Sensing in Fading Channels Sat, 07 Dec 2013 15:19:00 +0000 Cognitive radio (CR) is a promising technology for efficient utilization of underutilized spectrum since it is able to detect the occupancy of primary users (PUs) in the different parts of the spectrum. As the sensing channel uncertainties limit the reliability of the spectrum sensing decision, cooperation among multiple CR users is often used to improve the spectrum sensing decision. In this paper, the performance of single CR user based spectrum sensing and cooperative CR user based spectrum sensing (CSS) has been assessed in several channels such as AWGN, log-normal, Hoyt (or Nakagami-q), Rayleigh, Rician (or Nakagami-n), Nakagami-m, and Weibull channels. The performance of two spectrum sensing schemes based on assigning weights to CR users such as (a) weighting according to sensing channel preference and (b) weighting according to the value of decision statistic is evaluated. The performance comparison between two weighting schemes under several fading channels has been made. The performance of proposed CSS has been illustrated through complementary receiver operating characteristics (CROC) for different fading channels. The effects of weighting factors (k and Rf) on overall missed detection performance are shown. The performance of CSS with OR-logic fusion as a special case is also presented for comparison purpose. Srinivas Nallagonda, Shravan Kumar Bandari, Sanjay Dhar Roy, and Sumit Kundu Copyright © 2013 Srinivas Nallagonda et al. All rights reserved. A Sixth Order Accuracy Solution to a System of Nonlinear Differential Equations with Coupled Compact Method Wed, 04 Dec 2013 13:45:30 +0000 A system of coupled nonlinear partial differential equations with convective and dispersive terms was modified from Boussinesq-type equations. Through a special formulation, a system of nonlinear partial differential equations was solved alternately and explicitly in time without linearizing the nonlinearity. Coupled compact schemes of sixth order accuracy in space were developed to obtain numerical solutions. Within couple compact schemes, variables and their first and second derivatives were solved altogether. The sixth order accuracy in space is achieved with a memory-saving arrangement of state variables so that the linear system is banded instead of blocked. This facilitates solving very large systems. The efficiency, simplicity, and accuracy make this coupled compact method viable as variational and weighted residual methods. Results were compared with exact solutions which were obtained via devised forcing terms. Error analyses were carried out, and the sixth order convergence in space and second order convergence in time were demonstrated. Long time integration was also studied to show stability and error convergence rates. Don Liu, Qin Chen, and Yifan Wang Copyright © 2013 Don Liu et al. All rights reserved. Fluid Selection of Organic Rankine Cycle Using Decision Making Approach Mon, 02 Dec 2013 18:31:23 +0000 An attempt has been made to rank and classify potential fluids for power production through organic rankine cycle (ORC) using technique for order preference by similarity to ideal solution (TOPSIS) method. In order to calculate subjective weights for the attributes under study, the modified digital logic (MDL) method has been used. It has been observed under two different case studies that R601 (pentane) shows promising results. These fluids are further classified using dendrogram, a hierarchical clustering technique. Finally Pearson's correlation coefficient is calculated for the attributes to find out the nature and degree of correlation between different attributes under study. Aditya Chauhan and Rahul Vaish Copyright © 2013 Aditya Chauhan and Rahul Vaish. All rights reserved. Random Response Forest for Privacy-Preserving Classification Thu, 14 Nov 2013 09:21:07 +0000 The paper deals with classification in privacy-preserving data mining. An algorithm, the Random Response Forest, is introduced constructing many binary decision trees, as an extension of Random Forest for privacy-preserving problems. Random Response Forest uses the Random Response idea among the anonymization methods, which instead of generalization keeps the original data, but mixes them. An anonymity metric is defined for undistinguishability of two mixed sets of data. This metric, the binary anonymity, is investigated and taken into consideration for optimal coding of the binary variables. The accuracy of Random Response Forest is presented at the end of the paper. Gábor Szűcs Copyright © 2013 Gábor Szűcs. All rights reserved.