Papers by Leonardo Sandrolini
This paper deals with the issue of demonstrating electromagnetic and signalling compatibility bet... more This paper deals with the issue of demonstrating electromagnetic and signalling compatibility between two train control systems. In particular, the paper presents an analysis of mutual coupling between a legacy track circuit based train control system (TCS) and a transmission based train control (TBTC) system. The analysis focuses on the ability of the TBTC system to adversely impact the operation of the track circuit based TCS. The paper presents measurement and computational data, and concludes that due to the weak coupling between the TBTC and track circuit TCS, the induced voltage (and current) in the legacy system due to the TBTC does not present a EMI risk to the safe operation of the track circuit TCS.
IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics and Drives, 2011
This paper addresses the problem of robust and accepted methods for the estimation of electromagn... more This paper addresses the problem of robust and accepted methods for the estimation of electromagnetic emissions from electrical machinery and more extensively, Adjustable Speed Drives. Machine emissions can also be considered for diagnostic purposes. In particular, the analysis of the electromagnetic signature of the machine is used for the detection of partial short-circuits inside windings or mechanical unbalancing faults. The
2002 3rd International Symposium on Electromagnetic Compatibility, 2002
The magnetic field generated by a nonsinusoidal periodic source is shielded by a planar infinite ... more The magnetic field generated by a nonsinusoidal periodic source is shielded by a planar infinite multilayered shield composed of high permeability and high conductivity materials. By means of a transform analytical approach, the shielding effectiveness is calculated.
2003 46th Midwest Symposium on Circuits and Systems, 2003
This paper deals with circuit models that can be used to represent printed circuit lands of switc... more This paper deals with circuit models that can be used to represent printed circuit lands of switched-mode power supplies (SMPS). These circuit models are useful for the prediction of the electromagnetic emissions radiated from such converters. Representations of SMPS built on printed circuit board (PCB) in terms of lumped circuits and lumped-circuit iterative structures are considered and compared under different
2001 IEEE EMC International Symposium. Symposium Record. International Symposium on Electromagnetic Compatibility (Cat. No.01CH37161), 2001
In this paper a procedure for the optimization of multilayered shields for low-frequency magnetic... more In this paper a procedure for the optimization of multilayered shields for low-frequency magnetic fields is presented. The shield is optimized with respect to the total volume of the composing materials, being the magnetic flux density magnitude at test points in the shielded region smaller than a given threshold value. For simplicity, shields composed of two different materials only are
2010 Asia-Pacific International Symposium on Electromagnetic Compatibility, 2010
A procedure for the extraction of the complex permittivity as a function of frequency of dispersi... more A procedure for the extraction of the complex permittivity as a function of frequency of dispersive materials based on a Particle Swarm Optimization (PSO) method is presented in this work. The reconstruction of the complex permittivity is carried out from the knowledge of the aperture admittance obtained by an open-ended coaxial probe. The results obtained show a good agreement with those in the literature. The procedure has a general character as it can be applied to different materials, measurement techniques and dielectric relaxation models, provided that the analytical relation between a quantity that can be measured with that technique and the complex permittivity is known.
IEEE Transactions on Industry Applications, 2015
ABSTRACT Leakage currents from a dc electrified railway requires careful consideration throughout... more ABSTRACT Leakage currents from a dc electrified railway requires careful consideration throughout the life time of the railway. The design objective is to minimise the current leakage from the railway return path (the running rails for a dc electrified railway, with possibly additional conductors in parallel for ac electrified systems). For this objective to be met, the design needs to account for foreseeable misuse during the construction phase (i.e., the lack of independency between the earthing system and stray current collection system due space and construction exigencies in a viaduct) and degradation of insulation due to ageing and poor maintenance. Perhaps more importantly, other influences such as the train characteristics, time tabling, headway, multiple train movement, etc., need consideration to determine the worst case leakage current and thus the ability to define appropriate mitigations with respect to stray current management. In this paper, we describe the implementation of an integrated model for the assessment of stray current for a dc electrified railway, in which these factors are considered. We provide an analysis of the stray current magnitude under worst case train operating conditions (i.e., multiple trains with a 90s headway accelerating) as well as highlight factors that determine the efficiency of the stray current collection system. The integrated model presented enables a detailed assessment of all factors impacting the stray current magnitude as well as an assessment of the overall performance of stray current collection system.
IEEE 6th International Symposium on Electromagnetic Compatibility and Electromagnetic Ecology, 2005., 2005
This paper investigates by means of numerical simulations the influence that different heatsink c... more This paper investigates by means of numerical simulations the influence that different heatsink configurations have on the generation of radiated emissions. The effects of a subdivision of the heatsink among the different switching devices of a switched-mode power supply are examined. The plots of the electric near field for different excitation conditions are analyzed in terms of the surface current
2009 International Symposium on Electromagnetic Compatibility - EMC Europe, 2009
In this paper simple theoretical and experimental procedures are presented in order to assess the... more In this paper simple theoretical and experimental procedures are presented in order to assess the surface resistivity and shielding effectiveness of electrically conductive textiles. Whereas predictions of the shielding effectiveness may be difficult, the surface resistivity can be estimated quite accurately with a simple method. Two methods for the measurement of the shielding effectiveness of conductive textiles are employed, the
IEEE Transactions on Device and Materials Reliability, 2015
ABSTRACT For the first time, the degradation rate of the electrical parameters in thin-film solar... more ABSTRACT For the first time, the degradation rate of the electrical parameters in thin-film solar cells based on CdS/CdTe materials is simulated numerically using the Analysis of Microelectronics and Photonic Structures (AMPS-1D) program. This time-dependent approach attributes the defect generation rate to the excess carrier concentration profile. The degradation rate is analyzed for the devices stressed under the open-circuit, short-circuit, illumination, and dark conditions. Illuminated open-circuited devices showed a faster degradation rate than the short-circuited and dark-rested ones. This instability was mostly driven by the loss in the fill factor relevant to the increased series resistance. A separate analysis of the degradation behavior arisen from the holes and electrons indicates that the holes degrade the device slightly stronger than the electrons. In the CdTe thin films, the drift mobility of the holes is an order of magnitude lower than that of the electrons, which allows a longer interaction of the holes with the semiconductor lattice. Starting from the simplest device structure, e.g., Gloeckler model, the calculations are extended to the defect increment at the very thin layers placed at the front and back regions of the device. Both layers caused an almost similar degradation trend but a slightly faster rate when the thin defective layer was placed at the junction. This time-dependent approach can be extended to simulate the degradation behavior of the electrical parameters in other thin-film devices, such as CIGS and CZTS materials, under the different stress conditions leading to the different defect distribution across the device thickness.
2007 IEEE International Symposium on Electromagnetic Compatibility, 2007
The efficiency and reliability of the multiple-mode transmission line theory applied to predict t... more The efficiency and reliability of the multiple-mode transmission line theory applied to predict the electromagnetic coupling between electric monopoles with conducting planes inside a metallic enclosure is assessed in this paper. The planes are represented with an equivalent impedance through a transmission line analogy. Particularly critical coupling configurations, such as close monopole-to-plane and plane-to-plane configurations are tested. The results obtained
2008 Asia-Pacific Microwave Conference, 2008
This paper is devoted to investigate which basic mechanisms are responsible for the major part of... more This paper is devoted to investigate which basic mechanisms are responsible for the major part of the shielding of conductive textiles by means of measurement of the shielding effectiveness (SE). Both woven and nonwoven textiles with different thickness, nickel amount and fabric geometry are examined. Results show that the electrically conductive textiles tested present different SE and surface resistivity values
2006 IEEE International Symposium on Electromagnetic Compatibility, 2006. EMC 2006., 2006
This paper investigates the low-frequency electromagnetic interference (EMI) from switched-mode p... more This paper investigates the low-frequency electromagnetic interference (EMI) from switched-mode power supplies (SMPS) by electromagnetic field coupling. The interferences are calculated by means of equivalent circuits that represent the weak magnetic and electric field coupling between the EMI sources of a SMPS and a reference victim circuit. The inductive and capacitive parameters of the equivalent circuits are calculated by simple
IEEE 6th International Symposium on Electromagnetic Compatibility and Electromagnetic Ecology, 2005., 2005
The prediction of the shielding effectiveness of concrete structures is a fundamental aspect of t... more The prediction of the shielding effectiveness of concrete structures is a fundamental aspect of the architectural design phase of purpose built control centres. These buildings designed with a functional requirement to house sensitive control equipment; malfunction of such equipment may lead to loss of life and impact on revenue service. In this paper, a simple analytical approach is proposed to influence the design of buildings such that the structure provides adequate attenuation to hostile electromagnetic ambient and potential electromagnetic pulses. Comparison with numerical methods is provided. The effect of moisture content on the shielding effectiveness of a concrete wall is outlined.
2006 17th International Zurich Symposium on Electromagnetic Compatibility, 2006
Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands ... more Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands a detailed understanding of its properties. Besides experimental measurements, mathematical models can be useful to investigate its behaviour with respect to frequency, moisture content or other agents. These models can be used in EMC to predict the shielding effectiveness of a concrete structure against external electromagnetic waves. This paper presents a comparison between an analytical approach that relies on measurements, and numerical simulations that make use of dispersion models. The comparative results demonstrate that the analytical approach, which is more computationally efficient than numerical solvers, can be used to predict the shielding effectiveness of concrete structures.
2012 Asia-Pacific Symposium on Electromagnetic Compatibility, 2012
In this work the radiation of the electromagnetic field due to partial discharges throughout the ... more In this work the radiation of the electromagnetic field due to partial discharges throughout the insulation spacer of Gas Insulated Switchgears is investigated. Radiation can be described in terms of resonant modes of the slot between the metallic bolts. Moreover other resonant modes due to the spacer flanges are observed and investigated for the first time.
Journal of Power Sources, 2007
A nonlinear circuit model of a polymer electrolyte membrane (PEM) fuel cell stack is presented. T... more A nonlinear circuit model of a polymer electrolyte membrane (PEM) fuel cell stack is presented. The model allows the simulation of both steady-state and dynamic behaviour of the stack on condition that the values of some of its parameters are changed in the two operating conditions. The circuit parameters can be obtained by means of simple experimental tests and calculations. A commercial PEM fuel cell stack is modelled as seen from the power conditioning system side, without requiring parameters necessary for complex mathematical models and not easily obtainable by the majority of users. A procedure of parameter determination is developed and a comparison between the simulated and experimental results for both steady-state and dynamic behaviour of the PEM stack is shown.
Journal of Physics D: Applied Physics, 2007
Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands ... more Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands a detailed understanding of its electrical properties. Besides experimental measurements, material theoretical models can be useful to investigate its behaviour with respect to frequency, moisture content or other factors. These models can be used in electromagnetic compatibility (EMC) to predict the shielding effectiveness of a concrete structure
IEEE Transactions on Magnetics, 2000
A two-dimensional analytical solution for quasistatic magnetic field shielding with planar infini... more A two-dimensional analytical solution for quasistatic magnetic field shielding with planar infinite multilayered shields is presented. The magnetic field source is a system of long straight wires parallel to the shield, carrying sinusoidal currents. The analysis assumes that material media can be considered linear under the applied source fields. The spatial Fourier cosine and sine transforms are applied to the analytical expressions of the magnetic field intensity and flux density is obtained by solving the diffusion equation in each layer. Using transfer relations for every layer in terms of transformed variables allows one to obtain the shielded field, and thus the shielding effectiveness, with no need to determine the integration functions explicitly. The results obtained with both this approach and a finite-element computer code are in good agreement. The method seems to be also suited for the analysis of problems with more complex geometries and source distributions.
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Papers by Leonardo Sandrolini