Narrow Results

An acoustic wave signal measured on the gas pipe due to impact force is transfer to the far distance through the medium inside of duct. This signal is very complex since it includes the acoustic wave and solid wave. Acoustic wave is affected by the cavity mode inside of duct. The analysis of this acoustic wave gives information about the impact force. For the analysis of this signal, the correlation technique has been used for a long time. This method has a limitation for the application since the waves have dispersive and cavity mode characteristics for the flexible wave. In this paper, we present the time-frequency method for the identification of impact force and the location of impact on the gas pipe. The results give the useful information for the impact force and are applied to the analysis of leakage location of the gas pipe.

The steady-state and transient electron transport in ZnO field effect transistor have been studied using an ensemble Monte Carlo simulation which takes into account the hot-electron transport phenomena. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible, and the predicted I–V and transfer charateristics for the intrinsic devices show fair agreement with the available experimental data. Simulations of the effect of modulating the gate bias have also been carried out to test the device response and derived the frequency bandwidth. The value of 80 ± 5 GHz has been derived for the intrinsic current gain cut-off frequency of the ZnO MESFETs.

A detailed analysis of static and dynamic characteristics of deep submicron double and single gate SOI MOSFETs is presented, based on 2D numerical simulations for high frequency analog applications. Results show that although DG MOSFET offers excellent performance with respect to short channel immunity and higher transconductance, it offers nearly two times the value of gate-to-source capacitance as compared to SG devices, thus limiting the cut-off frequency at higher gate voltages. At ultra short channel lengths and low gate overdrive voltages, DG devices show a significant improvement in cut-off frequency compared to SG devices, thus presenting DG nanotransistors as potential candidates for analog microwave applications.

In this paper, a hydroelastic model is considered to examine the trapped modes supported by a horizontal submerged cylinder placed in either of the layers of a two-layer fluid flowing over an elastic bottom at a finite depth. The elastic bottom is modeled as a thin elastic plate and is based on the Euler–Bernoulli beam equation. Using multipole expansion method, an infinite system of homogenous linear equations is obtained. For a fixed geometrical configuration and a specific arrangement of a set of other parameters, the frequencies for which the value of the truncated determinant is zero are numerically computed and the trapped wavenumbers corresponding to those frequencies are obtained by using the dispersion relation. These trapped modes are compared with those for which the lower layer is of infinite depth. We also look into the effect of the variation of the elastic plate parameters on the existence of trapped modes. Significant difference is observed with respect to the existence and also in the pattern of the trapped modes between the present case and the one when the cylinder is placed in an infinite depth lower layer of a two-layer fluid.