Marco Raugi

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 and design of an electromagnetic system for the characterization of magneto-rheological fluids for haptic interfaces

In this paper, the synthesis and design of a new device for the energization and characterization of magneto-rheological fluids (MRF) for haptic interfaces are presented. Due to the core structure and feeding conditions, only a three-dimensional numerical analysis provides an accurate prediction of the electromagnetic quantities and the rheological behavior of an excited specimen. The design constraints are shown in details and the results in terms of magnetic field inside the fluid and its spatial resolution are discussed.

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.

Plug-and-Play Distributed Algorithms for Optimized Power Generation in a Microgrid

This paper introduces distributed algorithms that share the power generation task in an optimized fashion among the several Distributed Energy Resources (DERs) within a microgrid. We borrow certain concepts from communication network theory, namely Additive-Increase-Multiplicative-Decrease (AIMD) algorithms, which are known to be convenient in terms of communication requirements and network efficiency. We adapt the synchronized version of AIMD to minimize a cost utility function of interest in the framework of smart grids. We then implement the AIMD utility optimisation strategies in a realistic power network simulation in Matlab-OpenDSS environment, and we show that the performance is very close to the full-communication centralized case.

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

Electromagnetic Modeling and Design of Haptic Interface Prototypes Based on Magnetorheological Fluids

We report on the design and implementation of innovative haptic interfaces based on magnetorheological fluids (MRFs). We developed 2D and quasi-3D MRF-based devices capable of suitably energizing fluids with a magnetic field in order to build shapes that can be directly felt and explored by hand. We obtained this effect by properly creating a distribution of a magnetic field over time and space inducing the fluid to assume a desired shape and compliance. We implemented different prototypes, synthesized and designed with the help of preliminary simulations by a 3D finite-element code. In this way, both magnetic field and shear stress profiles inside the fluid could be carefully predicted. Finally, we evaluated and experimentally assessed the performance of these devices.

Magnetic field evaluation for thick annular conductors

The three-dimensional integration of the Biot-Savart law for conductors in annular sector shape, in which only a constant-density theta -directed current flows, is reported. The expressions obtained allow a quick and accurate evaluation of the components of the vector potential of the stationary magnetic field and of the magnetic induction due to this type of conductor, in iron-free media. The relations presented, together with similar expressions that are valid for other shapes of conductor and current distributions, can be useful for evaluating the magnetic fields in complex, linear, iron-free structures when the geometry can be well approximated with a series of current elements of elementary shape, for which the solution of Laplaces equation is known in closed form. >

Analytic expressions for magnetic field from finite curved conductors

Some analytical expressions for the calculation of the magnetic induction and the vector potential in iron-free media due to conductors in annular arc shape with regular cross section are reported. The algorithms derived, together with analogous algorithms reported previously for the calculation of the magnetic fields due to conductors in slab shape, can be used to calculate the magnetic fields in more complicated geometries and may be used to evaluate the self- and the mutual-inductance coefficients in systems with massive conductors.