摘要:

The Wigner‐Ville distribution (WVD), generally calculated by the fast Fourier transform (FFT), is a useful tool for time‐frequency signal analysis. However, for nonstationary multicomponent signals, the inherent bilinear structure of the WVD causes undesirable interfering cross terms, and becomes troublesome to many applications. The FFT requires complex arithmetic computations, but the fast Hartley transform (FHT) only requires real arithmetic computations. Therefore, the FHT performs much faster than the FFT. An improved WVD computation using the FHT and running windowed exponential distribution is proposed in this paper. The cross‐terms of nonstationary multicomponent signals can be completely eliminated, and the result is favorable for pattern recognition and signal classification. The derived algorithm is also applied to building up a real‐time processing scheme for conducting experiments in an anechoic chamber.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677770

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A vector implementation of sensitivity computation that can be used in the remedial action planning of N‐1 steady state security assessment function is presented in this paper. In order to exploit the power of vector processors, the formulations of sensitivity calculation are restructured to minimize the execution time and the effects of data storage scheme are investigated. Tests of the proposed schemes are conducted on Alliant FX/80 and Convex 3840 machines. Test results have shown that the execution time required for obtaining a large set of sensitivity factors can be greatly reduced by using the proposed schemes on vector computers.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677771

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Developing turbulent pipe flow in the inlet region of a smooth circular pipe at Re=194,000 (based on the pipe radius and the bulk velocity) and fully developed turbulent flow at Re=215,000 are simulated with sixk‐ϵturbulence models, including one high‐Reynolds‐number model and five low‐Reynolds‐number models. The fully elliptic forms of nondimensional governing equations in cylindrical coordinates are solved. The predictions for the axial mean velocity, turbulent energy, Reynolds stress, friction velocity and the growth of turbulent boundary layer are compared to available experimental data. The results show that most models have satisfactory predictions of the axial mean velocity; however, the turbulent kinetic energy and the Reynolds stress predicted by those models in the inlet region of the pipe have some discrepancy from the experimental data. From the relative performance of the models, the model of Chien (1982, AIAA J., Vol. 20, pp. 33–38) has a better simulation than the others.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677772

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, the procedure of normalizing load‐deflection curves of lateral piles in a homogeneous elasto‐plastic soil is presented. An analytical method using subgrade reactions reveals that the normalized relation of load‐deflection exists for force, moment or combined load. The normalized curves for force and moment load fit very well with the predictions using the equations. For the combined load, the normalized curves are distributed between the force and moment load curves, so it is easy to use interpolation from a family of curves. These normalized curves provide a very convenient way for calculating the pile load or deflection in the design stage.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677773

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677758

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor