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Home>Products>Journal and Reviews>I.RE.Mo.S.>Latest issue
International Review on Modelling and Simulations - June 2009 - Papers
International Review on Modelling and Simulations - Papers
Vol. 2. n. 3, pp. 227-235
Abstract - In this
paper, a neural approach is applied to determine the switching angles
for a uniform step asymmetrical multilevel inverter by eliminating
specified higher-order harmonics while maintaining the required
fundamental voltage. A Multi-Layer Perceptron (MLP) neural network is
used to approximate the function between the modulation rate and the
required switching angles. After learning, the artificial neural network
is able to determine the appropriate switching angles for the inverter.
This leads to a low-computational-cost neural controller which is
therefore well suited for real-time applications. This technique can be
applied to multilevel inverters with any number of levels. As an
example, a nine-level inverter and an eleven-level inverter are
considered and the optimum switching angles are calculated on-line. The
neural approach is compared to the well-known sinusoidal Pulse-Width
Modulation (PWM) strategy. Simulation results demonstrate the better
performances and technical advantages of the neural controller in
feeding an asynchronous machine. Indeed, the harmonic distortions are
efficiently cancelled providing thus an optimized control signal for the
asynchronous machine. Moreover, the technique presented here
substantially reduces the torque undulations.
Keywords: Uniform Step Asymmetrical Multilevel Inverter, Harmonics Elimination Strategy, Artificial Neural Networks, Multi-Layer Perceptron, Sinusoidal Pulse-Width Modulation.
Vol. 2. n. 3, pp. 236-243
Abstract - This paper investigates the effect of neutral ground resistance on the ferroresonance behavior of a three phase transformer. For simplicity only fundamental ferroresonance (FF) solutions has been addressed. Harmonic balanced method has been used to formulate an analytical solution to the problem of fundamental frequency ferroresonance (FF) in a three phase system. Continuation has been used to study ferroresonance circuit around parameter space when a control parameter is varied. Time domain simulation has been carried out and compared with analytical solutions. The results reveal that the presence of neutral resistance, even a low value, has a major role on FF stability domain. Different scenarios like one phase and two phase switching have been studied. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Ferroresonance, Nonlinear Circuits, Three Phase Transformers.
Vol. 2. n. 3, pp. 244-248
Abstract - The object of the present paper is double. First, a detailed synthesis of undamped synchronous machine models is presented. Second, a general procedure for main flux saturation modelling in smooth air-gap synchronous machines, that is applicable for all possible models, is described. The method avoids the magnetic couplings between the direct and quadrature axes, known in the literature as cross-saturation phenomenon. The concept is here restricted to saturation modelling in synchronous machines with no dampers. A number of models that result from the application of the method for different selections of state-space variables are detailed in the paper. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Smooth Air Gap Synchronous Machines, Synthesis, Modelling, Cross saturation.
Vol. 2. n. 3, pp. 249-253
Abstract - The aim of this paper is to present a new approach for multiconductor transmission line (MTL) analysis in frequency–domain. Exact MTL admittance matrix, in the sense of the finite element method, can be proclaimed as a finite element matrix and the standard assembly procedure, inherent to FEM, can be applied. Thanks to assembly procedure, complex networks with distributed and lumped parameters can be treated. The proposed approach arises from application of the finite element method (FEM) on MTL problems and capability of modern computational tools. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Finite element method, Multi-conductor transmission line, Frequency domain, Electromagnetic transient, Network analysis.
Vol. 2. n. 3, pp. 254-258
Abstract - A MATLABTM simulation program is present to show chaotic behavior. The chosen circuit to display chaos phenomenon was Chua oscillator. This particular circuit is analyzed in detail, being solved, first with kirchoff laws and later on by a numerical method in order to solve the differential order equations that results from the current equations of the kirchoff laws. Chua oscillator has several linear components, but has also a non-linear component that is known as Chua’s diode. This non-linear component is made of diodes and a negative resistor. The concept of a negative resistor is explained in this article. It is shown how to generate a sequence of chaotic behaviors by varying the value of a linear resistor. The results are displayed in the form of MATLABTM generated graphics. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Chaos, Chua, Forward Euler, MATLABTM, Non-linear circuits, Oscillator.
Vol. 2. n. 3, pp. 259-263
Abstract - This paper proposes a new control scheme for the dynamic voltage restorer which employs the dq rotating reference frame because it offers more accuracy and simplicity as compared with the stationary frame-based techniques. In the proposed control scheme, the reference voltage for the control system is determined by a new algorithm that has been developed to implement the minimum energy compensation technique in the dq-frame for both balanced and unbalanced sags and Swells .The validity of the proposed method is demonstrated by simulation studies carried on a typical distribution system under balanced and unbalanced sags. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Series Compensation Technique, Dynamic Voltage Control System, Minimum Energy Compensation.
Vol. 2. n. 3, pp. 264-268
Abstract - In this paper a precise and simple methodology will be introduced for modeling and calculating the Voltage Source Inverter (VSI) losses in Hybrid Electric Vehicles (HEV) application. The noteworthy traction inverter losses, consisting switching and conduction losses of diodes and IGBTs, are important for evaluating the overall efficiency and obtaining the optimized value of its dc-link voltage as well. For this purpose, the effects of different battery voltage levels on the inverter losses are examined. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Hybrid Electric Vehicle (HEV), Voltage Source Inverters (VSI), Loss Modeling, Power Converters for HEV.
Vol. 2. n. 3, pp. 269-273
Abstract - Contamination- driven insulator failure is a problem that incessantly plagues power system. It corrodes power quality and diminishes system reliability. In this paper, the principal pollution flashover models are reviewed and then a model for flashover under ac voltage is introduced. The model takes into account the parameters of the pollution. This model is constructed on ATP software and is used to simulate the polluted insulator flashover in power system. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Pollution, Flashover, ATP, AC voltage, Model.
Vol. 2. n. 3, pp. 274-281
Abstract - This
paper describes and analyses the performance of a commercial air-cooled
absorption chiller. This analysis is based on the first and second law.
A steady state model using the exergy method is developed and some
working parameters are varied to evaluate the system performance. The
used model involves operating parameters such as overall heat transfer
coefficient of each component (UA), air cooling temperature, and chilled
water inlet temperature. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Exergy, Absorption, Refrigeration, Second law, COP.
Vol. 2. n. 3, pp. 282-296
Abstract - In this paper the modeling and control of two-wheel inverted pendulum mobile robot (TWIP) using feedback linearization method is discussed. The dynamic model of a TWIP mobile robot is derived based on Lagrange method. The condition of the model then has been checked for strong accessibility and maximum relative degree for the purpose of state feedback linearization controller design. Based on these result it is known that the partial feedback linearization controller can be formulated which forms as main contribution of this work. With the proposed of sub-optimal tuning algorithm, the controller parameters is tuned iteratively. This hybrid control has give an extra advantage to the controller in action to perform the tracking of TWIP orientation and heading speed, while maintaining the pitch angle within specified range. The structure of this newly proposed controller is decomposed into two level of controllers which are named low level controller (LLC) and higher level controller (HLC). LLC is used to maintain the inclination angle of the TWIP within a pre-specified allowable range while the HLC is meant for tracking the TWIP heading speed. The new HLC design is based on Lyapunov’s direct method in which the convergence of the tracking error of the heading speed is guaranteed. Also, in order to ensure the dynamic stability of the system is preserved, the dynamic of HLC is set to be slower than LLC by adapting a reconfigurable delay term in HLC design. The verification of the performance of the controller under various system conditions is done through simulation work. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Velocity control, Partial feedback linearization, Iterative tuning, Nonlinear system.
by Abbas Golmakani, Khalil Mafinejad, Abbas Kouzani Vol. 2. n. 3, pp. 297-303
Abstract - This paper presents a new method for design and optimization of analog integrated circuits based on Pareto-based Multi-Objective Genetic Algorithm (MOGA). The efficiency of the method is evaluated by using benchmark problems and compared with other MOGA algorithms. The method is implemented and used to optimize a telescopic cascode Op-Amp. Here, transistor sizes, compensation capacitor and bias voltages are determined by Genetic Algorithm (GA). Moreover, the circuits that are formed, using the components of the determined values, are simulated with Hspice. The output parameters, such as gain, bandwidth, phase margin and power are extracted from the generated output file, and the area of chip is calculated separately. The extracted output parameters are used as cost functions for creating next generation in GA. Finally, a set of Pareto-front which satisfies the conditions of the problem is introduced. This enables the circuit designer to select the best solution from the set. This algorithm is implemented in Matlab and is simulated by using Hspice and TSMC 0.18um CMOS technology is employed in simulation. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Multi Objective Genetic Algorithm, Pareto Front, CAD Tools, Op-Amp, Optimization.
by M. Daoud, B. Yagoubi Vol. 2. n. 3, pp. 304-309
Abstract - In this work, we have applied two recent methods; the Discrete Wavelet Transform (DWT) and the Empirical Mode Decomposition (EMD) combined with the Hilbert transform, to the heart rate variability (HRV) considered as non-stationary and non linear signal, in order to study the autonomous nervous system (ANS) behaviour. The latter can be characterised by the power spectral density in the low frequency (LF) to that in the high frequency (HF) bands ratio. The RR (beat to beat) intervals data were taken from the HRV signals of young and old men watching a fantasy film. The sympatho-vagal balance ratio (LF/HF) estimation results obtained in our case using these two methods indicate that the parasympathetic activities are, generally, more dominant in the case of the young men, whereas the ANS sympathetic behaviour is clearly dominant for the old men. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: ANS, HRV, FFT, DWT, EMD, HHT.
Vol. 2. n. 3, pp. 309-314
Abstract - Studies of pollution of porous laminates and transfers water in unsaturated soils have attracted the attention of many researchers. These studies have intensified since it was found that soil contamination could have serious impacts on the environment, flora and fauna. In this work, a two-dimensional study will be conducted to simulate the pollutant transfer of a laminate floor. The equations obtained are solved numerically using the finite volume method. We observed the behavior of water content and concentration as a function of different layer study. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Stratified porous media modeling; Transport of Pollutants; Unsaturated zone; Two-dimensional.
by Zitouni N., Andoulsi R., Sellami A., Mhiri R. Vol. 2. n. 3, pp. 315-323
Abstract - This paper presents a Bond Graph (BG) modelling of ultraviolet (UV) water disinfection pilot unit fed by a photovoltaic source. This unit is intended to be mainly used in rural zones where the water availability is often rare. The use of the photovoltaic modules as source of energy is an adequate solution considering the dispersion of the sites. However, the sunning variation during the day poses the problem of energy storage. For that, we used electrochemical batteries which present the best solution by their good adaptation to photovoltaic source. The ultraviolet irradiations are used to solve the bacteriological problem of the drinking water quality. A gas-discharge lamp is used to produce this type of radiation. A centrifugal motor-driven pump ensures the circulation of treated water between the two tanks (input and output) through UV lamp. The pilot unit presents a complex model because of his hybrid components. For that we used the bond graph methodology to present the B.G models of the various unit elements and a global model for simulation is carried out. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Bond-graph, Photovoltaic, UV water disinfection, battery storage, modelling and simulations.
by D. Kiouach, L. Omari Vol. 2. n. 3, pp. 324-327
Abstract - In this work we consider the SIR (Susceptible - Infected -Removed) epidemic model with infection and removal rates of general form f(S, I) and g(S, I) respectively. To calculate the final size of this model we give a recursive method using the embedded chain. Then we make a numerical calculation for some particular infections and removals rates. Our method we allow calculating the final size for a large population and for all values of basic reproduction number, so it is very fast. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Final Size, SIR, Stochastic Model, Markov Process, Embedded Chain.
by B. Radjenović, M. Radmilović-Radjenović Vol. 2. n. 3, pp. 328-332
Abstract - In this paper we have shown that profile evolution during anisotropic wet etching of silicon can be described by the non-convex Hamiltonian arising in the Hamilton-Jacobi equation for the level set function. Angular dependence of the etching rate is calculated on the base of the silicon symmetry properties, by means of the interpolation technique using experimentally obtained values of the principal <100>, <110>, <111> directions in KOH solutions. Some examples illustrating developed methodology are presented. The calculations are performed using an extension of the sparse field method for solving three dimensional (3D) level set equations in the case of non-convex Hamiltonians. The obtained results indicate that the sparse field level set method can be used as an effective tool for wet etching process modeling. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Level set method, Wet etching, Profile evolution, Three dimensional simulations.
by Mahmoud Imed, Rehaoulia Habib, Ayadi Mahfoud, Ben Salah Boujemaa Vol. 2. n. 3, pp. 333-340
Abstract - The subject of this paper is a novel form of linear stepper motor based purely on variable-reluctance principle, for biomedical applications. The design of geometrical dimensions of the linear motor used in biomedical systems is presented. We try to reduce the phase current, in order to keep constant the consigned maximal force, by insertion of permanent magnets in the stator that lead to a hybrid structure (MPPH). Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: CAO, Finite-Element Analysis, Linear Incremental Actuator, Permanent Magnet, Switched Reluctance.
by V. Wieser, N. Majer, J. Haring Vol. 2. n. 3, pp. 341-345
Abstract - In this paper the method for radio channel pulse response processing with baseband conversion by six-port reflectometer technique is described. The received signal is converted by baseband conversion, digitized and the pulse response of radio channel is processing by proposed algorithms. These algorithms are working in real time and are able to estimate the amplitude, phase and delay of the received signal in each of propagation paths. The most promising algorithm (Exponential Power Descend Algorithm) achieved recovery successfulness of all signal paths equal approximately 90 % for SNR = 2.5 dB. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Pulse response, Radio channel, Six-port reflectometer, Pulse response processing algorithms.
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