摘要:

This study mainly relates the gravity‐surface‐waves generated when a uniform flow passes through a bulging bed. This is done firstly by treating the linear surface waves generated when a uniform flow passing through single wave bed, then, secondly, by making use of the fundamental solution obtained as mentioned above, and coordinating it with the Fourier integral and contour integral, so that the gravity surface wave generated by the more generalized and simple wave bed can be treated. With respect to the analytical solution, the major premise of this assumption is still limited to the uniform and irrotational flow, and at the same time neglecting the influence of surface tension, in order to obtain the analytical result of the flow field. It is important to propose possible methods to analyze the surface wave generated by any form of bulging bed, so that the problem of gravity surface waves generated by the bulging bed can be reasonably solved by the analytical method.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677126

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The responses of transient SH waves propagating in a double dipping layered medium overlaying half‐space are investigated in this study. To obtain the responses, a line source, with a parabolic ramp and a triangular time function is assumed to be located in the top dipping layered medium. Then the generalized ray theory and Cagniard method [13], were employed to solve the problems of the first and second wave trains respectively. Finally, the ray paths and responses for the distinct locations on the surface are obtained and are shown in the sketches. As for the total responses, it is found that the consideration of the responses for the second wave train in far field is more important than in near field.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677127

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper, implementation of a simulation system for flexible manufacturing cells (FMC) based on a local area network is outlined. Four sets of IBM‐compatible PC's are used to represent the machines in an FMC, which consists of a CNC milling machine, a CNC lathe, an industrial robot, two pallet stands and a cell controller. One PC is used as the cell controller. Two PC's are used as simulators of the milling machine and the lathe. Real‐time graphic animations of tool paths are produced according to the scheduled part programs. The fourth PC simulates the loading and unloading tasks of the robot. The control softwares for the workstations are obtained from the control goal diagrams, which are derived from the system event graph by decomposition. All events which occurred in the simulation are viewed in graphic images. Upon completion of the simulation, a statistical performance report is produced.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677128

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Based on the feedback linearization structure algorithm of differential geometric nonlinear control theory, an external linearization approach to the control of multi‐link flexible joint robots is considered in this paper. The resulting externally linearized and input‐output decoupled closed‐loop system describing the rigid motor motions is suitable for the design of nominal trajectory following control. However, there still exists a nonlinear joint deformation subsystem causing perturbations in the nominal trajectory. To rapidly damp out the elastic vibrations and to render the complete closed‐loop system robust to uncertainty in system parameters, a combined LQR stabilizer and servocompensator is used as the perturbed stage control. The tracking errors of the end effector caused by joint deflections due to gravity and inertia force can be compensated for by taking into account the nominal deflections in both the trajectory planning and LQ regulation. A three‐link PUMA type arm is tested via simulation.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677129

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper, we consider the problem of robust controller synthesis with noise spectral uncertainties and nonlinear time‐varying unmodeled dynamics in the LQG (linear‐quadratic‐Gaussian) optimal systems. We derive a robust stabilization criterion for multivariable stochastic systems with nonlinear time‐varying unmodeled dynamics. Meanwhile, we shall frame up an algorithm for synthesizing the robust controller not only to minimize the least favorable cost functionalJbut also to satisfy the robust stabilization criterion via specifying an appropriate weighting scalar in the cost functional. The Wiener‐Hopf's technique in LQG optimal system, the saddle point theory, the Nevanlinna‐Pick interpolation theory, and a property of the contractive operator are employed to treat this problem. Furthermore, there are no stable and minimum phase constraints on the controlled plant.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677130

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Some novel numerical results of a lumped loaded straight wire are demonstrated and discussed. These include the scattering properties changed by impedance loading; the spectrum spread by nonlinear impedance loading; the effectiveness of providing “false” Doppler frequency and spreading the spectrum of the scattered returns by time varying loading. In this study, a parameter called the modulation index, is defined to measure the effectiveness of the loading on the above phenomena. It is found that reactive loading affects the scattered field more drastically than resistive loading does. Therefore, reactive type loading is more effective than resistive type loading for providing false Doppler frequency and spreading the spectrum of the scattered waves.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677131

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Quantization is an essential mechanism in analog‐to‐digital conversion and proper design of the quantizer to minimize quantization error is important to digital signal processing systems. Many cost functions have been proposed as the distortion measure for the actual design of a quantizer, and non‐mean‐squared error criteria are often presented as physically significant. One of the non‐mean‐squared error criteria frequently discussed is the meanrth power error distortion measure. In this paper efficient methods for the design of minimum meanrth power error quantizers are presented and demonstrated by numerical examples. A closed form solution of minimum mean absolute error quantization for‐ Laplace‐distributed signals is also provided. Compared with previous work, the simple algorithms discussed in this paper are more accurate.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677132

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Based on expanding the matrix fraction descriptionB(z)A‐1(z), whereA(z) andB(z) are matrix polynomials inz, into bilinear matrix continued fractions corresponding to the Schwarz form, a model reduction method is presented for discrete multi‐input multi‐output systems. Both frequency‐domain and time‐domain reduced‐order modeling procedures using the bilinear block Schwarz form are given. Examples for the construction of a bilinear block Schwarz form and its application to model reduction are also given.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677133

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In the present study, the nonparametric method of system identification proposed by Masri et al. has been used to treat simulated earthquake response data of a bridge with nonlinear foundations. It is found that the method is promising for estimation of functions which represent the dynamic characteristics of bridges and provides a sound basis for study of the safety assessment of a bridge by using earthquake response data of the bridge.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677134

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The technique of real‐time holographic interferometry is used in the present study to study natural convection in a fully‐partitioned air‐filled square enclosure. Transient and steady‐state temperature distributions in separated subenclosures are visualized for a Rayleigh number between 2.5×105and 8.4×105with a centrally‐located conducting partitions. Steady‐state experimental results are found to be in reasonably good agreement with the numerical predictions. Moreover, the experimental observations during the transient one‐sided heating processes indicate that the presence of a conducting partition can provide a good buffer against a sudden external disturbance to the enclosure.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677135

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor