236 research outputs found
Shrinking horizon parametrized predictive control with application to energy-efficient train operation
No full textA nonlinear model predictive control approach is studied, for problems where a fixed terminal instant and corresponding terminal set to be reached are imposed. The new technique features a shrinking horizon, rather than the most common receding one, and an input parametrization strategy to reduce computational burden. The property of transferability of the parametrization strategy is introduced. Under this property, theoretical convergence guarantees in nominal conditions are obtained by construction. Two relaxed techniques are then proposed to retain recursive feasibility in presence of bounded additive input disturbance. A bound on the constraint violation achieved by these relaxed techniques as a function of the uncertainty bound is derived, too. The developed strategy is applied to the problem of energy-efficient operation of trains, in either a fully autonomous mode (with continuous input values) or a driver assistance mode (with discrete input values, resulting in a nonlinear integer program if no parametrization is used). Realistic simulation results in this context illustrate the effectiveness of the approach
Application prospective of Silicon Carbide (SiC) in railway vehicles
No full textSilicon Carbide (SiC) power switches are new generation semiconductor devices with really interesting properties that can be suitable exploited in railway application to reduce weight and size of the power converters, increasing at the same time their efficiency. The paper presents their properties, their current application in railway vehicles and their future developments
Experimental investigation of self-heating effects in semiconductor resistors during TLP pulses
No full textThe purpose of this work is the experimental extraction of the local maximum temperature occurring in
silicon resistors when a transmission line pulse is applied. The local temperature is extracted by combining transmission line pulses of
different amplitude and at different ambient temperatures with two-dimensional electrothermal simulation. This investigation has
relevant practical applications. The obtained calibration curves enable to convert the phase shift information as obtained by
interferometric techniques (e.g. in Transient Interferometric Mapping) into absolute temperature readings. Moreover, relevant physical
parameters (e.g. resistivity) can be extracted as a function of the temperature by transient heating, i.e. by avoiding the detrimental
artifacts involved with the static heating of semiconductor samples at high temperatures. This enables to calibrate device simulators at
those high temperatures, which are required for the simulation of ESD events
Study of the 32S(3He,d)33Cl one-proton transfer reaction with a new generation hodoscope
No full textThe 32S(3He,d)33Cl one-proton transfer reaction is a powerful tool to investigate the spectroscopy of low-lying states in the proton-rich 33Cl nucleus. However, the extraction of firm differential cross-section data at various angles, against which benchmarking theoretical models to correctly constrain the spectroscopy of 33Cl, is made challenging by the presence of competitive reaction products contaminating the detected energy spectra. We have recently measured the 32S(3He,d)33Cl reaction at 9.8 MeV incident energy by using a new generation hodoscope of silicon detectors, capable to detect and identify emitted deuterons down to energies of the order of 2 MeV. The high angular segmentation of our hodoscope allowed to unambiguously disentangle the contribution of one-proton transfer reactions in the ground state of 33Cl and in its 0.810 MeV, 2.352 MeV, 2.685 MeV, 2.846 MeV excited states from contaminant deuteron-emitting reactions. These data will be crucial to help to constrain Jπ and spectroscopic factor C 2 Sp values of low-lying 33Cl states, still ambiguous in the literature. The present status of the analysis is discussed in the paper
Study of the 32S(3He,d)33Cl one-proton transfer reaction with a new generation hodoscope
No full textThe 32S(3He,d)33Cl one-proton transfer reaction is a powerful tool to investigate the spectroscopy of low-lying states in the proton-rich 33Cl nucleus. However, the extraction of firm differential cross-section data at various angles, against which benchmarking theoretical models to correctly constrain the spectroscopy of 33Cl, is made challenging by the presence of competitive reaction products contaminating the detected energy spectra. We have recently measured the 32S(3He,d)33Cl reaction at 9.8 MeV incident energy by using a new generation hodoscope of silicon detectors, capable to detect and identify emitted deuterons down to energies of the order of 2 MeV. The high angular segmentation of our hodoscope allowed to unambiguously disentangle the contribution of one-proton transfer reactions in the ground state of 33Cl and in its 0.810 MeV, 2.352 MeV, 2.685 MeV, 2.846 MeV excited states from contaminant deuteron-emitting reactions. These data will be crucial to help to constrain Jπ and spectroscopic factor C 2 Sp values of low-lying 33Cl states, still ambiguous in the literature. The present status of the analysis is discussed in the paper
33Cl Spectroscopic Factors via the 32S(3He, d)33Cl One-Proton Transfer Reaction
No full textThe structure of light-to-medium mass nuclei is crucial to understand exotic phenomena in nuclear structure, including the appearance of molecular effects in light nuclei and their impact in nuclear astrophysics. In this paper, a new experiment to probe one-proton spectroscopic factors of bound and unbound states in the sd-nucleus 33Cl is discussed. The experiment exploits the reaction 32S(3He, d)33Cl* at 9.68 MeV bombarding energy. This reaction is suitable to probe the single-particle structure of 33Cl states with respect to the population of 1d 3/2, 1f 7/2 and 2p 3/2 shells. Crucial aspects of the investigation are the use of an enriched, high-purity, 32S target and a new generation hodoscope with improved angular resolution, allowing to obtain high-precision angular distribution of the differential cross section in a broad angular range. Results are interpreted by means of finite-range DWBA and coupled-channel calculations
33Cl Spectroscopic Factors via the 32S(3He, d)33Cl One-Proton Transfer Reaction
No full textThe structure of light-to-medium mass nuclei is crucial to understand exotic phenomena in nuclear structure, including the appearance of molecular effects in light nuclei and their impact in nuclear astrophysics. In this paper, a new experiment to probe one-proton spectroscopic factors of bound and unbound states in the sd-nucleus 33Cl is discussed. The experiment exploits the reaction 32S(3He, d)33Cl* at 9.68 MeV bombarding energy. This reaction is suitable to probe the single-particle structure of 33Cl states with respect to the population of 1d 3/2, 1f 7/2 and 2p 3/2 shells. Crucial aspects of the investigation are the use of an enriched, high-purity, 32S target and a new generation hodoscope with improved angular resolution, allowing to obtain high-precision angular distribution of the differential cross section in a broad angular range. Results are interpreted by means of finite-range DWBA and coupled-channel calculations
New investigations on the 32S(3He,d)33Cl reaction at 9.6 MeV bombarding energy
No full textThe 32S(3He,d)33Cl one-proton transfer reaction is a powerful tool to investigate the spectroscopy of low-lying states in the proton-rich 33Cl nucleus. However, the extraction of firm differential cross-section data at various angles to benchmark and constrain theoretical models is made challenging by the presence of competitive reactions on target contaminants. In this paper we report on arecent measurement using a new generation hodoscope of silicon detectors, capable to detect and identify emitted deuterons down to energies of the order of 2 MeV. The high angular segmentation of our hodoscope combined with a suitable target to control possible contaminants, allowed to unambiguously disentangle the contribution of various states in 33Cl, in particular the 2.352 MeV state lying just few tens of keV above the proton separation energy
New investigations on the 32S(3He,d)33Cl reaction at 9.6 MeV bombarding energy
No full textThe 32S(3He,d)33Cl one-proton transfer reaction is a powerful tool to investigate the spectroscopy of low-lying states in the proton-rich 33Cl nucleus. However, the extraction of firm differential cross-section data at various angles to benchmark and constrain theoretical models is made challenging by the presence of competitive reactions on target contaminants. In this paper we report on a recent measurement using a new generation hodoscope of silicon detectors, capable to detect and identify emitted deuterons down to energies of the order of 2 MeV. The high angular segmentation of our hodoscope combined with a suitable target to control possible contaminants, allowed to unambiguously disentangle the contribution of various states in 33Cl, in particular the 2.352 MeV state lying just few tens of keV above the proton separation energy
Measurement and modeling of the electron impact-ionization coefficient in silicon up to very high temperatures
No full textAbstract—In this paper, an experimental investigation on high-temperature electron impact-ionization in silicon is carried out with the aim of improving the qualitative and quantitative understanding of carrier transport under electrostatic discharge (ESD) conditions. Special test devices were designed and manufactured using Infineon’s SPT5 technology, namely: a bipolar junction transistor (BJT), a static-induction transistor (SIT) and a vertical DMOS transistor (VDMOS), all of them with a cylindrical geometry. The measurements were carried out using a customized measurement setup that allows very high operating temperatures to be reached. A novel extraction methodology allowing for the determination of the impact-ionization coefficient against electric field and lattice temperature has been used. The experiments, carried out up to 773 K, confirm a previous theoretical investigation on impact-ionization, and widely extend the validity range of the compact model here proposed for implementation in device simulation tools. This is especially useful to predict the failure
threshold of ESD-protection and power devices
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