Search results for "Transient response"
showing 6 items of 36 documents
Stimulated nutation echo: application to the driven decoherence study
2003
We study experimentally the dynamical and decay properties of the stimulated nutation echo (SNE) in a two-level spin system, the signal of which allows the observation timescale of the driven coherence relaxation to be extended. This signal appears in the transient response of the system to the second pulse at time τ1 from its start and coinciding with the duration of the first pulse. The information about the first pulse duration is imprinted into the population difference of the inhomogeneously broadened ensemble of the two-level absorbers. The decay of the SNE signal has two contributions. One originates from the population decay during the time τ between the two pulses. Another is cause…
SPICE model for resistive gas and odour sensors
1999
A generalised PSPICE model of resistive gas/odour sensors is presented. The model simulates the response of both polymeric and metal oxide devices, as well as an integrated resistive heater that is used to set the operating temperature. In both cases there was good agreement between the observed responses and the PSPICE simulated responses to rectangular pulses of gases. The PSPICE model is not only simpler and faster to use than analytical solutions, but also should permit the rapid prototyping of associated drive circuitry.
A fuel cell-supercapacitor power supply for portable applications
2008
Due to the increasing number and complexity of the available functions, modern handheld devices require higher and higher current slew rates. Customers' requirements lead to a growing interest in longer-lasting power, fast transient response power supply systems and minimization of system weight, volume and cost. Fuel cell based hybrid systems are designed to meet all requirements. In this paper, a fuel cell-supercapacitor hybrid power supply for portable applications is proposed. The power management subsystem is designed and simulation results are shown to test the efficiency of the control algorithm. ©2008 IEEE.
Time evolution of the microwave second-order response of YBaCuO powder
2003
Transient effects in the microwave second-order response of YBaCuO powder are investigated. The time evolution of the second harmonic signal has been measured for about 300 s after the sample had been exposed to variations of the DC magnetic field. We show that in different time scales the transient response has different origin. In the time scale of milliseconds the transient response of samples in the critical state is ascribable to processes of flux redistribution induced by the switching on/off of the microwave field. At longer times, the time evolution of the second harmonic signal can be ascribed to motion of fluxons induced by the variation of the DC magnetic field. In particular, di…
One-sensor electronic olfactometer for rapid sorting of fresh fruit juices
2001
Abstract A low-cost electronic olfactometer was developed, based on virtual sensors array (an array of signals from a single metal oxide sensor) and on our proprietary semi-automated sampling system. This concept enables us to drastically improve the sensitivity and selectivity of the entire olfactometer to make it suited to food products analysis. Each step of the prototype was checked separately in earlier work, and finally the system performance was evaluated first on pure chemicals, and then at-line for grape juice during grape-harvesting in Champagne. It is shown that over a 3-week vintage period, the drift of the unique-sensor was quite low (absolute baseline value: avg., 2152; std., …
An Impulse Response Model for the 60 Ghz Channel Based on Spectral Techniques of alpha-stable Processes
2007
International audience; In order to make realistic simulations of the radio propagation mechanism in ultra-wide band channels, an appropriate model is needed. In this paper we propose a new technique to model the impulse response of the 60 Ghz channel. This new approach is based on the spectral analysis of alpha-stable processes. Our new model presents many advantages: firstly, the channel is characterized only by a one deterministic function (spectral density) in the place of four parameters. Secondly, the estimations procedure deals directly with the measured transfer functions which avoids loosing information in data pretreatment. Finally, an estimation of the spectral measure permits to…