Sami Barmada

Innovative model for time-varying power line communication channel response evaluation

This work presents a channel model for the broadband characterization of power lines in presence of time variation of the loads. The model is characterized by taking into account both measured and geometrical channel characteristics and can easily be used to take into account also the presence of noise. The channel is described by a two-port equivalent described by a scattering matrix determined from a wavelet-based expansion of the input and output quantities. Upper and lower bounds for the response of the channel in presence of time-varying loads are determined in a fast and efficient way avoiding time consuming Monte Carlo simulations. The bounds determination allows the estimate of noteworthy quantities for the tuning of currently used modulation schemes for power lines communications such as orthogonal frequency-division multiplexing.

Transient numerical solutions of nonuniform MTL equations with nonlinear loads by wavelet expansion in time or space domain

This paper deals with the numerical solution of nonuniform transmission lines (TLs) with nonlinear loads. The method presented here is based on the wavelet expansion; a weak formulation of the TL equations is obtained by expanding voltages, currents, and operators by means of wavelet functions. The TL equations are transformed into algebraic equations where the differential operator is represented by a matrix and the unknowns are the coefficients of the wavelet expansion of voltages and currents. The numerical efficiency of the method is tested analyzing uniform, nonuniform lines and nonlinear loads. The results are compared with results obtained by means of different methods.

Analysis of Power-Line Communication Channels in Ships

This paper presents a theoretical and experimental analysis on the application of power-line communication (PLC) on a cruise ship. The authors have developed an accurate model of the power grid of a ship when it is used as a PLC channel. The model is developed based on a theoretical approach and validated by a thorough measurement campaign. The accuracy of the model is addressed by a comparison between simulation results and measured data, and its use gives an insight into the performance of the power network to be used as PLC channel.

Analysis of the performance of a multi-stage pulsed linear induction launcher

In this paper the performance of a multistage pulsed linear induction launcher (PLIL) is analyzed. Attention is focused on the phenomena occurring during the transition between two adjacent stages and on the effects of the coaxial deviation on the motion of the sleeve. The possibility of contacts between the sleeve and the flyway tube and their dynamics is investigated. The analysis has been performed by means of an integral formulation of Maxwell equations that results in an equivalent time varying network. Mechanical coupling has been taken into account assuming a rigid sleeve with three degrees of freedom; the first two are related to the motion of the mass center and the third one is related to rotation around it. Thermal coupling has been considered assuming that the ohmic losses are dissipated adiabatically in the stator windings and in the sleeve. The model has been tested by comparison with results obtained by other researchers in the analysis of a single stage pulsed induction launcher. The analysis of a capacitor-driven five stage launcher has been performed. As the speed of the barrel increases the armature capture effect becomes more evident; the number of contacts with the flyway tube increases and the impacts happen at higher velocity.

A General Tool for Circuit Analysis Based on Wavelet Transform

This paper deals with a generalized method for the time-domain solution of electrical networks. The aim is to explore a new technique for the numerical simulation of circuits considering linear, time-varying and non-linear cases. By using the wavelet transform of the electrical quantities, differentiation and integration in the time domain are replaced by matrix multiplication. Then, the classical circuit differential equations obtained by mesh-current, node-voltage or state variables methods are transformed in algebraic equations. The numerical efficiency of wavelets makes the method effective for a fast and reliable numerical circuit simulation. Comparisons with analytical solutions and PSPICE simulations are presented in order to evaluate the numerical characteristics of the proposed method. Copyright

A Wavelet Based Method for the Analysis of Impulsive Noise Due to Switch Commutations in Power Line Communication (PLC) Systems

The aim of this paper is to study the problem of load-time variation in power line communication (PLC) systems and to analyze asynchronous impulsive noise and related channel variations due to switch commutations. A numerical model of the time-varying communication channel is developed by using scattering parameters in the wavelet domain. The proposed method uses the N-port description of the elements that constitute a time-varying PLC system in terms of real matrices with constant elements. This represents a valid alternative to the time domain description usually adopted for analyzing time-varying networks. The comparison with results obtained from other numerical models and with experimental data has confirmed the accuracy and the efficiency of the proposed method.

Analysis of the performance of a combined coil-rail launcher

An electromagnetic system that operates both as a rail and as a coil launcher is proposed, and its performance is analyzed. The device has a composite stator that consists of two rails properly slotted in order to allow the presence of a system of coils. The armature consists of a conductive slab sliding between the rails. Another system of slots is present in the armature where a system of short-circuited coils is placed. A source of constant voltage is connected to the rails and the current flowing in the armature through the sliding contacts produces a thrust force on it. If a proper system of currents able to produce a traveling wave of flux density in the region between the rails is used to feed the barrels, the induced currents that flow in the armatures short-circuited coils produce a further thrust force on the armature itself. The analysis of the behavior of this launcher is performed via a computer code based on an integral formulation and a tool that analyzes the phenomena related to the velocity skin effect; the interactions between the two systems of currents on the armature and the currents on the stator (rails and barrels) are investigated. The thermal behavior of the device has been taken into account by a simple adiabatic model since the short operating time allows one to neglect heat diffusion in the conductive parts of the system. A comparison between the velocities, respectively obtained by separately feeding rails and coils and the system with the combined feeding, has been performed. Preliminary results of the analysis show that this device, because of the presence of two systems of thrust forces acting on the armature, can be successfully used in the acceleration of heavy masses at relatively high velocities, the maximum achievable speed being limited by thermal and mechanical stresses.

Two-port equivalent of PCB discontinuities in the wavelet domain

A novel wavelet-based technique is presented for the extraction of two-port equivalents of common printed circuit board (PCB) discontinuities. The wavelet-transformed scattering parameters of the discontinuity can be included in a wavelet equivalent of TEM wave propagation paths along the PCB in order to obtain an overall equivalent of the whole structure under analysis. The wavelet representation minimizes the CPU time and computer storage requirements while maintaining excellent accuracy, thus, it proves to be a very useful modeling tool, especially in the design stage.

Power Line Communication in a full electric vehicle: Measurements, modelling and analysis

The Power Line Communications technology is now considered as a good alternative for implementing communication grids also in vehicles, with the main scope consisting in reducing the cable harness. In this paper we present the first results relative to a study performed on a fully electric vehicle. Due to the peculiar characteristics of the power grid in electric vehicles (topology and noise), this study is important to verify whether the PLC technology is applicable also in this case.

PLC systems for electric vehicles and Smart Grid applications

In this paper an extensive set of measurements, simulations and testing of a commercial modem are performed in an electric vehicle to evaluate the performance of PLC. The noise of the motor drive is measured and characterized in the time and frequency domains. Also, the noise generated by the AC/DC converter is measured and described. The symbol-error-rate performance of a multicarrier communication scheme is analyzed via simulation by employing the above modeled channels and noise.