ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677627

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A microprocessor‐based slope‐varied frequency‐pumped controller (μP‐SVFPC) for improving the locking performance of the frequency‐locked position servo control system (FLPS) is presented. The presented slope‐varied pump technique is to perform the position control process fast for a long distance servo, while nearly similar acquisition times for different distance servos are obtained during the servo range. The motion profiles for system locking are adaptively generated according to the coming frequency error. No motion profiles are required to be pre‐installed in the controller. A prototype ofμP‐FLPS is realized, simulated, and tested. Computer simulation and experimental result confirm that the system acquisition times ofμP‐FLPS for short, middle, and long distance servos are nearly similar to each other. In comparison with the basic FLPS system, the acquisition times of the presentedμP‐FLPS for the middle and long distance servos are improved by about 58% and 85%, respectively.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677628

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A binary asynchronous direct sequence spread spectrum multiple access system through Nakagami's m‐distributed channel is considered for non‐diversity receptions. Effects of fading and multiple access interferences on the average error probability are investigated. Approximation method to the average error probability is evaluated in two steps based on the moments of multiple access interferences and Nakagami distributions. Gauss quadrature rule is applied to evaluate the conditional probability conditioned on a fixed m‐distributed fading amplitude of the desired signal. Average error probability is then evaluated by the trapezoidal integration which integrates the conditional probability and the m‐distributed probability density function of the desired signal. This method provides a good approximation to the average error probability when the number of simultaneous users is large. Numerical results for the pseudorandom codes of code length 31 and Gold codes of code length 31 and 127 are presented.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677629

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Droplet combustion processes of benzene andn‐heptane liquid fuels, including heating, evaporation, ignition and burning, are numerically investigated and compared with the available measured results found in the literature. Investigation shows that the consideration of thermal radiation effect does not introduce too many differences of ignition‐time predictions in the modeling compared to that obtained without thermal radiation effect. However, the predicted ignition times associated with the assumption of semitransparent droplets are mostly in agreement with the measured ones. In contrast, the difference between the predictions of the burned‐out time with and without thermal radiation effect are significant. Finally, the assumption of constant thermophysical properties in the modeling leads to some prediction errors, in comparison with the model associated with the variable thermophysical properties, but this is relatively minor.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677630

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An attempt is made to generate impedance matrices for two independent axial symmetric foundations on an elastic layered medium. The analytic solution of three dimensional wave equations for a layered medium with the prescribed traction due to vibration of one axial symmetric foundation can be found using the technique developed in Refs. [3,4,5]. Two analytic solutions for two prescribed tractions due to the vibrations of two axial symmetric foundations are found separately. The principle of superposition is then used to obtain the final solution. The interaction stresses at the interfaces between the foundations and layered soil medium are assumed to be piecewise linear inr‐directions of both cylindrical coordinates for two axial symmetric foundations. Then, the variational principle and reciprocal theorem are employed to generate the impedance matrices for both foundations. Some numerical results of impedance matrices for the interaction of two closely spaced circular foundations are presented, in order to show the effectiveness and efficiency of the presented method and the effect of layered stratum on the vibrations of two independent foundations. Discussion and conclusions are made.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677631

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

There are four passing bands in an infinite truss beam. For an incident bending wave from any branch of a cross‐type structure encountering the conjunction of these four branches of this structure, the induced wave modes in each branch can be predicted by using their dispersion of passing bands. The energy carried by this incident bending wave will be redistributed into these branches by the induced wave modes. The total energy value is conservative. Enlarging the cross‐sectional area or stiffening the material of horizontal members of all dissimilar cells around the outlets of this conjunction substructure enhances the power reduction in the two branches perpendicular to the incident direction. On the other hand, the induced power flow in the branch whose direction is the same as the incident direction can be reduced by stiffening the cross‐sectional area or stiffening the material of diagonal members of these three cells.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677632

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The pyrolysis kinetics of cellulosic toilet tissue paper, which is one of the principal materials contributing to municipal solid waste (MSW) in Taiwan, was investigated by a thermal gravimetric analysis (TGA) reaction system. The experiments were carried out over the temperature range of 450–850 K at various heating rates, and in a nitrogen atmosphere.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677633

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper presents an efficient method of determining soil parameters for finite element analysis of deep excavation. Due to the limitation of soil tests, field measurements are often used to calibrate in‐situ soil properties. This process is time consuming and computationally cumbersome. In this paper, nonlinear optimization techniques are applied to determine the unknown parameters of an objective function, which is defined as the sum of the square of differences between observed and predicted values. The convergence and stability of the optimization algorithm are confirmed by three well‐known mathematical functions and a hypothetical excavation case under varied ground conditions. Finally, a case study is presented to show the reliability of the proposed soil parameter determination procedure.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677634

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Laboratory tests and in‐situ seismic cone penetration tests are conducted to evaluate the liquefaction resistance of Lanyang sandy soils. Resonant column tests and cyclic torsional shear tests are performed on remolded samples to establish the relationship between the maximum shear modulus and the liquefaction resistance. The relationship is used to predict the in‐situ liquefaction resistance. Test results show that liquefaction resistance predicted byCPT‐qcis consistent with the one predicted by maximum shear modulus. From the comparisons, the maximum shear modulus is found to be a good index in assessing in‐situ liquefaction resistance.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677635

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this paper, a stable variable structure control (VSC) scheme is studied. With the existence of a sliding regime and the occurrence of hitting, a new approach to determine the switching gains of a variable structure stabilizer with uncertain parameter is presented. With the assignment of an eigenstructure when designing the switching plane, and the incorporation of appropriate switching gains to form the sliding regime, the system dynamic performance can be improved. Based on the bounds of uncertainties the proposed algorithm is a systematic procedure.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677636

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor