Catálogo de publicaciones - libros

We compare different model reduction methods applied to the dynamical system of a coupled transmission line: balanced truncation (BT), truncation by balancing one gramian (or PMTBR - poor man's truncated balanced reduction), positive real balanced truncation (PRBT) and its Hamiltonian implementation (PRBT-Ham), PRIMA, spectral zero method (SZM) and its Hamiltonian implementation (SZM-Ham), and finally, optimal . Their performance is analyzed in terms of several criteria such as: preservation of controllability, observability, stability and passivity, relative and norms, and the computational cost involved.

This paper deals with the transient simulation of large, nonlinear magnetoquasistatic field models which are monolithically coupled to electric circuits. Solid- and stranded-conductor models embedded in the field model are connected to the external circuit. In order to guarantee the numerical efficiency of the field-circuit coupled formulation, conductor models coupling the circuit to the field at a reference crosssection, have to be preferred over conductor models that couple the whole conductor volume to the circuit. The circuit is formulated in terms of both voltage drops and currents in order to avoid fill-in in the field matrix parts. For time stepping, an error-controlled, adaptive singly diagonally Runge-Kutta method is applied. A dense output solution is used to detect and localise switching events in the circuit. The actual time step is restricted to the time instant of switching at which consistent initial conditions are determined before restarting the time integration. The transient field-circuit coupling is applied to the models of a capacitor motor and a three-phase transformer.

The number of physical effects that have to be taken into account to accurately model and design current and future micro- and nano-electronics devices is continuously increasing. At the same time, the importance of the coupling among them is increasing as well. An accurate simulation of such effects with strong interactions is often non-trivial and in many cases a satisfactory solution is not yet available. Two challenging problems are presented in more detail: the first one refers to the thermomechanical problem of silicon oxidation, the second is the electrical coupling which occurs in strained silicon substrate.

Atmospheric aerosols exhibit a high degree of variability in their properties and their spatial and temporal distribution. Laser remote sensing is now-days used to provide systematic monitoring of the temporal evolution of the aerosol in order to understand the radiative, physical, chemical and dynamic processes in the atmosphere. In this paper, we present a new method for solving the inverse problem in LIDAR sounding based on a hybrid regularization procedure.

In this communication we present the CoMSON Demonstrator Platform (DP), a software tool designed to help researchers in testing and validating models and algorithms for coupled simulation of nanoelectronic circuits and devices. The structure of the DP is presented with an explanation of the motivations behind the critical design choices. A multilevel simulation of a CMOS AND gate using two different coupling algorithms is provided as an application example. The example is intended to demonstrate the suitability of the DP as a flexible prototyping environment and its ability to cope with real life industrial problems. In the numerical simulations both the semi-classical Drift-Diffusion model (DD) and a Quantum Corrected DD model (QCDD) are employed and their predictions are compared.

The paper presents an investigation of the magnetic field influence within low voltage switching process in vacuum, in the case of strong currents interrupting. The axial, transverse and radial magnetic field action upon the vacuum electric arc behavior is analyzed on a mono-phase model. The conclusions obtained by modeling the electromagnetic field in the vacuum quenching chamber are compared with the experimental results. The experimental set-up can reproduce the real switching conditions of the power vacuum circuit-breaker. The goal of the study is the improvement of the circuit-breaker switching capabilities.

Next-generation nano-scale RF-IC designs have an unprecedented complexity and performance that will inevitably lead to costly re-spins and loss of market opportunities. In order to cope with this, the aim of the European Framework 6 CHAMELEON RF project is to develop methodologies and prototype tools for a comprehensive and highly accurate analysis of complete functional IC blocks. These blocks will operate at RF frequencies of up to 60 GHz. In this paper an overview of the CHAMELEON RF project will be given and the first results achieved in the CHAMELEON RF project will be presented.

The paper reports the use of Finite Element (FE) simulation and experiments meant to explore the operation conditions of the PieZoelectric wafer Transducer (PZT). Piezoelectrics is the coupling of structural and electric fields and may be solved using the multi-physics approach. Accordingly, three different multiphysics models were developed to investigate a plane strain problem. The first one includes two PZTs mounted on an aluminium plate and is used to model both the emission and reception signals. The next two ones are developed to separately model the emission and detection processes, in order to decrease the computational effort. The wave displacements are generated by a PZT-like actuator and the output voltage is obtained at a PZT receiver both by a multi-physics approach. The analysis considered the transducer lengths, the effects of the finite pulse width, the pulse dispersion and the detailed interaction between the piezoelectric element and the transmitting medium. The transmitted and received signals for so-called A0 and S0 modes have maxima close to the frequencies predicted in other works. A series of sensitivity curves relating the generation and receiving of Lamb waves were also determined and plotted as a function of the pulse center frequency and of the PZT lengths.

In a load-commutated synchronous motor, the torque is driven by the currents in the stator windings, and these currents depend on the rotor position. Since the stator phases are star-connected, the static torque generated by two stator phases connected in series and powered with a constant current offers sufficient information to design a suitable current control strategy. The synchronous machine studied has a reverse type of construction. The switching sequence for the current inverter is correlated with the rotor position by magnetostatic simulation in FLUX2D, using the maximization of static torque as optimization criteria. This study also covers a computational method for determining the operating parameters of a synchronous machine using simulation of the Standstill Frequency Response Test (SSFR).

This paper presents a possibility of modelling the electromagnetic field, by taking into account the symmetry of the domains. The domain discretisation and implicitly the finite volume shape will be derived from the type of the symmetry. Thus, a reduction of the problem size, as well as a guaranteed symmetry of the solution, and a better approximation of the borders and of the discontinuity surfaces are achieved.