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Home>Products>Journal and Reviews>I.RE.Mo.S.>Latest issue
International Review on Modelling and Simulations - October 2008 - Papers
International Review on Modelling and Simulations - Papers
by D. Fathi, B. Forouzandeh
Abstract - In this paper a new approach for evaluating propagation delay of global interconnects in FPGAs is presented. Using the proposed modeling method, we derive new enhanced accuracy expressions for the computation of the delay. For verification purposes, we perform interconnect delay simulations in several nanoscale technology nodes. The obtained results in delay computations, show a better match between our proposed model and HSPICE simulations, with respect to the conventional techniques such as Pi-model for the global interconnects. According to the obtained results, the difference between our model and HSPICE simulations is (0.11-3.26) percent, whereas this difference is (11.13-38.29) percent for another model. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: FPGA, Global Interconnect, Propagation Delay, Buffer Insertion, Nanoscale.
Abstract - It is important to know the thermal behaviour of a fast fuse for an optimal design as well as for a right choice of the fuse rating with the aim to protect the power semiconductor device. A 3D thermal model was developed in order to study the temperature distribution at a fast fuse. In this model the thermal behaviour of the fast fuse depends on the design of the fuselink elements, the material parameters and the ambient conditions. It was shown the temperature distribution through all fuselink elements. The simulated temperatures were compared with measured temperatures at defined points on the fuse. The simulation temperature values are in good correlation with experimental results which validates the proposed thermal model for the fast fuse. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: fuse, thermal analysis, modelling, simulation.
Abstract - The paper deals with a proposed coupled FE-BE method based on the coupling of the finite element and boundary element methods to compute parameters such as flux linkage, inductance and static torque of an 8/6 switched reluctance motor (SRM). The combination of both techniques in the same computer program is the most efficient way of tackling problems that contain features requiring both FE and BE capabilities. The conducting and magnetic parts of the motor are discritized by the finite element whereas the boundary element is used to discretize its air gap. The interfaces between the two methods’ domains were chosen to be circular to avoid the discontinuity of the normal vector at the corners of poles. To illustrate the merits of such proposed coupled FE-BE method, the obtained simulation results are compared to the prototype design values of this motor as cited in a given reference. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Switched reluctance motor, finite element method, boundary element method, static torque.
Abstract - In this paper the effects of some of stator parameters on flux density harmonic distortion in an interior permanent magnet synchronous motor (IPMSM) are presented. It is common sense that one of the main causes to deform magnetic flux density waveforms in an IPMSM is the stator slots. But the role of each section of slots in this phenomenon is different and it will be seen that some of them have insignificant effect, so that it can be neglected. In addition of slots, stator winding distribution with the aid of winding function theory will be analyzed also. For this purpose, with the aid of numerical and analytical calculations٫ flux density variations and harmonic distortion with respect to slot dimensions will be evaluated. Also harmonics of two different winding functions and their effects on magnetic flux density will be assessed. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Harmonic Distortion, IPMSM, Stator Slots, Winding Function.
Abstract - This paper consists in working out a monitoring system allowing the detection and the diagnosis of a revolving machine with the minimum of risks of error. Thus the fault detection or degradations by using the analysis vibratory and the estimate of the probability of detection through the Test of Bayes, enables us to envisage the new probability of survival through the function of the system’s reliability. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Analysis vibratory, Approach statistical, Monitoring, Petri net, Test of Bayes.
Abstract - The aims of this paper is to present an accurate internal model rotating of induction machines based on the multi-turns electric circuit magnetically coupled. The multi-turns electric equations expressed in two different coordinate systems, combined with the mechanical equations leads to a differential system which is reduced using the windings connection matrices. The model can be used in unbalanced parameters conditions with Wye or Delta stator windings connection. A three phase induction motor was simulated under normal healthy, stator inter-turns short-circuits and phase breakdown operations. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Induction motors, electric multi-turns equations, Short-circuits diagnosis, phase breakdown.
Abstract - This paper presents a comparison study of torque profiles of an in-wheel switched reluctance motor (SRM) with different winding configurations. Studied outer rotor SRM was designed for an in-wheel electric vehicle (EV) application, by authors. Both of the short pitched and fully pitched winding configurations are developed and analyzed. Torque profiles and ripple ratios, which are the most important parameters of in-wheel propulsion motors in EV applications, are compared for different current values, which correspond to various driving conditions of an EV. It is observed that, in short pitched wound in-wheel SRM, ripple ratio is calculated as 32,76%, similar to the conventional SRMs. With fully pitched winding configuration, torque output is increased between about 23% and 52%, depending on the current level. On the other hand, torque ripple is also greatly increased in the common operation interval of the propulsion motor, in spite of the decrease at low currents. Increasing ripple ratio makes this winding configuration inconvenient for in-wheel propulsion applications, unless any ripple control algorithm is applied. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fully pitched winding, in-wheel motor, ripple ratio, short pitched winding, switched reluctance motor, torque.
Abstract - In this paper, the influence of the number of nodes in the winding equivalent circuit on the surge voltages in transformers is investigated. By comparing the voltages at all the points obtained by dividing the winding into several number of elements, it is shown that the minimum number of elements required must be at least 8 elements when the winding’s neutral is connected to earth and 14 elements when the winding’s neutral is insulated from earth to keep the computational error less than 1%. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Transformer, Surge voltage, Equivalent circuit.
Abstract - DC electric arc furnace is an important nonlinear time-varying load in power system. Due to the adverse effects produced by the operation of arc furnace, it is important to build a practical model to describe the behaviour of electric arc furnace. This paper presents a DC Electric Arc Furnace the model is based on the stochastic nature of the electric arc current-voltage characteristic. Our model is consisting of four different structures basing on utilization of twelve power rectifiers for the study of harmonics in electrical networks. The model has been implemented using a numerical simulation environment to facilitate later analysis. Finally, the simulation results are compared with different structures of a DC EAF, when the Total Harmonic Distortion (THD) is determined and spectral representation to compares each structure is better in order. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: DC EAF, Electrical arc, Harmonics, Power Quality, Simulation.
Abstract - In this paper, a novel method for selecting an optimal branch conductor in a radial distribution system is presented. Power loss and voltage regulation as a function of length and cross section of a feeder conductor and an objective function for optimizing conductor cross section have been formulated. The main objective of optimal size conductor selection is to minimize the objective function which is the sum of capital investment and capitalized energy costs determined for each feeder using genetic algorithm approach. Maximum current carrying capacity and voltage constraints of feeder are taken into consideration. A 32 feeder radial distribution network is considered to demonstrate the effectiveness of proposed method . The advantage of this method lies in its faster convergence towards a global optimal solution. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Genetic algorithm (GA), distribution system planning (DSP), optimal conductor selection.
Abstract - The performance of Duty-Cycle Division Multiplexing (DCDM) using Amplitude Modulator (AM) and Mach-Zehnder Modulator (MZM) is reported. In a 30 Gb/s (3×10 Gb/s) system, DCDM with MZM (DCDM-MZM) performs better than DCDM with AM (DCDM-AM) in terms of system receiver sensitivity, optical signal-to-noise ratio and dispersion tolerance. The worst user in DCDM-MZM shows a receiver sensitivity and chromatic dispersion tolerance of –28 dBm and ±78 ps/nm at BER of 10-9 respectively. Without SPM effect, DCDM-MZM performs better than DCDM-AM. For both cases, the system experiences SPM effect at the same launched power which is around +10 dBm. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Optical Communication, Multiplexing, Duty-Cycle Division.
by H. Jouini, S. Chebbi, M. Annabi
Abstract - The unballasting of load is based, on the one hand, on the notion of the minimum and maximum frequency; i.e. ranges of acceptable frequency as well in transient as in statics for which are dimensioned the electric components, and other share, on the analysis of the electric characteristics of the system 5 moment of inertia time-constant and damping coefficient of the load. In this paper, we suggest a method of load’s unballasting in the Tunisian electric system through observation of the frequency and this, by introducing the method of frequency’s mixed criterion; this method combines the frequency’s unballasting with a technic that is based on the instantaneous frequency know as ROCOF (rate of change of frequency). Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Unballasting, metric-frequency, mixed criterion, admitted area of improving tendency, area of correcting tendency, instantaneous variation of frequency.
by T. Guesbaya, K. Benmahammed, A. Benali, D. Saiga
Abstract - In this paper the objective is to present local planner of trajectory based on the constraints method for nonholonomic mobile robot with avoidance of obstacles. The constraint method put some constraints on the permitted velocities of the mobile robot and obliges it to move away from the obstacles. Sometimes some heuristics rules must be used when the constraints method do not gives the suitable results (nil command) causing the blockage of the mobile robot. The mobile robot possesses ultrasonic sensors to measure the minimal distance into the obstacles. Modeling the obstacles and sensors by convex polygons makes the calculation methods of minimal distance easy. The simulation results show the suppleness with the mobile robot reach the target going across difficult path. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Avoidance, Constraints Method, Heuristic Rules, nonholonomic, Planner, Mobile Robot.
Abstract - The theoretical study, present here, deals with the problem of interaction pile soil, thus making a contribution in determining the resistance and friction edge side for a single stake sought by a charge axial static. The theoretical tool used is the theorem cinematic theory analysis limit, in the case of a material Coulomb, developing a model in three dimensions. The aim of this research is to determine the limit load massive breakdown by the model proposed using the computer code mathcad. The calculation program takes into account physical phenomena, ie the expansion and contraction of soil under a load static. The results, calculated by the proposed model are compared with experimental results made in the laboratory 3SR Grenoble (France) and the results of conventional methods used in the calculations of this type of constructions. The results obtained by this method are smaller than the results obtained by conventional methods and are similar to results of the experiment that we can conclude that this theory can be applied to calculations of the edge effect and the effect of friction piles. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Piles, loading static, constraint edge, lateral friction, kinematics, analysis limit.
Abstract - The aim of the work presented in this study is related to solar chimneys energy performances determination, and flow modelling analysis, according to certain dominant parameters. The analysis of the problem presented in this paper is structured into two parts: the first one, is corresponding to energy calculation, for the prediction of the performances, such as the output and the power delivered by a solar chimney power plant (SCPP), according to some geometrical and physical parameters, such as the height and the solar radiation. The second one is related to the modelling of the air flow in the chimney. It consists, in analysing a natural convective heat transfer problem, that take place in a solar chimney plant were the thermo- hydrodynamic aspects of the air flow through an axis symmetric system with well defined boundary conditions is examined. Obtained results are related to the temperature, and the velocity distributions in the device were they are determined by solving the energy, and the Navier and Stokes equations, by using the finite volume method. A specific consideration is given to identify the adequate position, in order to choose, and to optimize the site of the wind turbine in the chimney. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Solar Chimney, Heat Transfer, Numerical Simulation, Finite Volume Method.
Abstract - The GT-Power one dimension computational model of sequential injection dedicated compressed natural gas (CNG) engine has developed in this study. The engine model is used to simulate the intake gas flow pressure characteristics of diesel engine converted to CNG engine. The computational model considers the steady state and transient simulation processes of the intake port. The engine model size is developed from the real diesel engine data and input to software libraries. The simulation of engine model is running in variations engine speeds from 1000 until 4000 rpm. The simulation results are shown in the graph of this paper. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: CNG Engine, GT-Power, Intake Pressure, One Dimensional Modelling.
Abstract - Rolling burnishing is a less chip machining process which improves the treated surface integrity. It softens the surface quality and imposes compressive residual stresses. To know the influence of each parameter most of the studies done on this process remain experimental and then expensive .The aim of this work is to numerically analyze the evolution of the part properties after rolling. A two-dimensional model (2D) has been developed and a simulation by FEM has demonstrated the effect of different parameters related to the part or to the process. The model has allowed to determine the effect of the rolling effort, yield stress, coefficient of strain-hardening, rate feed and tool radius, on the treatment homogeneity and the residual stresses profile. The obtained results emphasise and light the conditions to be respected to optimize the rolling operation. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: roller burnishing, numerical simulation, residual stresses.
Abstract - For the applications of IR-UWB in human body’s sensing and detection, researchers and industries concentrate on the circuit design of the UWB transceiver and antenna. Very few work focuses on the significant part, the human body’s physical dimension through which the UWB signal propagate. This paper presents an approach to model the multi-tissue layer from the skin to the heart of a human body in a wideband of spectrum. The tissues act as a two-wire transmission line carrying a high frequency signal. Some of critical transmission line parameters such as characteristic impedance, propagation constant as well as its resistance, inductance, conductance, and capacitance per unit length are derived based on the transmission line theory and the human body featured from a cellular view. The distributed circuit of this transmission line model is implemented and simulated in a CAD tool. Simulation results provide the reflection and transmission factors at the boundary between two neighbor tissues (for example, between the lung and the heart) along with S-parameter analysis and attenuation in the tissues. The “body channel” model is very useful in the design of IR-UWB human sensing devices. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: IR-UWB Radar Detection, UWB Channel Model, Two-wire Transmission Line Model.
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