Design, analysis and implementation of a versatile low level radio frequency system for accelerating cavities

179 p.

Modelling and Simulation of ERTMS for Current and Future Mobile Technologies

Nowadays, train control in-lab simulation tools play a crucial role in reducing extensive and expensive on-site railway testing activities. In this paper, we present our contribution in this arena by detailing the internals of our European Railway Train Management System in-lab demonstrator. This demonstrator is built over a general-purpose simulation framework, Riverbed Modeler, previously Opnet Modeler. Our framework models both ERTMS subsystems, the Automatic Train Protection application layer based on movement authority message exchange and the telecommunication subsystem based on GSM-R communication technology. We provide detailed information on our modelling strategy. We also validate our simulation framework with real trace data. To conclude, under current industry migration scenario from GSM-R legacy obsolescence to IP-based heterogeneous technologies, our simulation framework represents a singular tool to railway operators. As an example, we present the assessment of related performance indicators for a specific railway network using a candidate replacement technology, LTE, versus current legacy technology. To the best of our knowledge, there is no similar initiative able to measure the impact of the telecommunication subsystem in the railway network availability.

Stability and Limit Oscillations of a Control Event-Based Sampling Criterion

This paper investigates the presence of limit oscillations in an adaptive sampling system. The basic sampling criterion operates in the sense that each next sampling occurs when the absolute difference of the signal amplitude with respect to its currently sampled signal equalizes a prescribed threshold amplitude. The sampling criterion is extended involving a prescribed set of amplitudes. The limit oscillations might be interpreted through the equivalence of the adaptive sampling and hold device with a nonlinear one consisting of a relay with multiple hysteresis whose parameterization is, in general, dependent on the initial conditions of the dynamic system. The performed study is performed on the time domain.

Metamaterialen simulazioa FDTD metodoaren bidez

Azken urteetan metamaterialek izugarrizko arreta eragin dute. Material artifizial horiek hainbat aplikazio ezberdin izateko diseinatzen dira eta horretarako, ikerkuntza haien propietate elektromagnetikoak ulertzean zentratu da. Lan honen helburua, hortaz, metamaterialen jokabide elektromagnetikoa ulertzea da. Horretarako, FDTD (Finite Difference Time Domain) metodoa erabiliko dugu Maxwell-en ekuazioak ebazteko. Oinarria ulertzeko, lehenik, uhin elektromagnetikoen hedapena aztertuko dugu ingurune sinpleagoetan eta ingurune desberdinen arteko muga-azalen jokabidea simulatuko dugu. Hori egin eta gero, amaitzeko, uhin elektromagnetikoen hedapena aztertuko dugu errefrakzio-indize negatiboko materialetan (metamaterialetan).