摘要:

With control input constraints, an adaptive control algorithm is proposed for a plant which is subject to unmodeled dynamics. By introducing an additional feedback signal, it is shown that the uniform boundedness of all signals in the adaptive loop is preserved. The true nominal plant is assumed to be stable but unnecessarily minimum phase. Moreover, various properties of this algorithm are analyzed. It is also shown that the performance which can be achieved under no control input constraint in the nonadaptive case (i.e. the case that the true nominal plant is known as a priori) is asymptotically well maintained in the adaptive system. The analysis is supported by simulation results.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677472

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In this study, we want to develop an efficient optimization algorithm based on Perturbation Analysis (PA) and compare the performance of PA with the traditional Finite Difference (FD) gradient method. While the FD estimate is a very time‐consuming gradient method, PA is a very promising algorithm in terms of the computational time. This is the major advantage of PA over FD. In this study, we use the property that PA only requires one simulation run to obtain other advantages of PA as a gradient method. First, we deal with the problem of initialization bias for the estimate of gradients of system performance. Second, we compare the efficiency of PA and FFD (which represents FD) in introducing the control variates variance reduction technique. Third, we propose a new method for determining the simulation run length at each iteration in an optimization algorithm. In the above three areas, we show that PA is better than FD. Finally, we combine PA and BM (batch means method) to obtain a more efficient gradient method, PA‐BM.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677473

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

DC potential drop has long been used for automatic crack length monitoring, yet details about its set‐up, causes of errors, precautions to achieve optimum performance and actual long term stability and accuracy under practical conditions have seldom been documented in detail. A DCPD system was established and details about its long term performance under varying loading and temperature parameters were evaluated. Necessary precautions to reduce error and improve accuracy are discussed. The system resolution is 0.003mm when applied to a compact tension specimen. The long term system accuracy achieved was ± 0.012mm. Two approaches for improvement were also attempted. It was found that the switch‐off approach at least doubled the accuracy and the reversing polarity approach raised the accuracy by nearly ten times. The improved system has been applied to a large pipe fracture specimen. The resulting empirical calibration data agrees closely with independently obtained finite element results.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677474

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A methodology of synthesizing images from the point of view of considering the object's recognizability is developed. The viewing parameters determining the synthesized image are decided based on the recognizability of the object. An object is identified through the determination of its position and orientation. In this paper, it is shown that we cannot distinguish topographically similar objects from a single perspective. Thus, the thresholdi,determined by a scheme developed here for modeli, is used to check whether a candidate model is accepted.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677475

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A robust stability index for a multivariable control system is proposed. On‐line robust control based on that index is then carried out. Filters are added in the feedback loops of the control system. The stability index enables on‐line tuning of the filters. Robust design with incorrectly given bounds on the modelling error is investigated. When the modelling error is smaller than or almost equal to the given bounds of error, the robustly designed systems give equivalent to or a little worse performance than that of the control system without robust design. But when the given bounds of error were much less than the actual size of the modelling error, the proposed design method improved performance significantly.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677476

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Fuzzy control is a type of knowledge‐based system. Its reasoning process is based on fuzzy logic and fuzzy set theory. The robustness and reliability of fuzzy control have been demonstrated in many cases, such as process control. However, fuzzy control usually demands a lot of computation time. In order to alleviate this restraint, a simplified fuzzy controller is developed for the purpose of real‐time control. It will be shown that the simplified fuzzy controller is a PID cotnroller plus a certain amount of nonlinearity. Under certain conditions, the simplified fuzzy controller reduces to a linear PID controller. Furthermore, a self‐organizing control based on the simplified fuzzy controller is also developed. Finally, a motion control example is used to illustrate the developments. The results show that, without degrading the performance, the simplified fuzzy control is about two hundred times faster than the conventional fuzzy control.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677477

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This paper applies a very efficient new technique, multi‐pass dynamic programming (MPDP) combined with successive approximations, to solve the weekly thermal unit commitment and hydrothermal generation scheduling problem. Conceptually, dynamic programming is suited for solving this problem, but the long computing time and the large storage memory required become unacceptable for large power systems and long scheduling periods. The MPDP technique can overcome these difficulties. Furthermore, the unit start‐up cost and pumped storage plants are considered in the hydrothermal coordination instead of only the production cost as in the previous application. The algorithm is tested on Taipower system with forty thermal units, seven conventional hydro units and one pumped storage plant. The results show that this method is suitable for practical systems.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677478

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

On the site of the Large Scale Seismic Test at Lotung, Taiwan, an in‐situ pore water pressure measurement program has been ongoing since 1986. Its purpose is to measure the changes in ground pore water pressure due to earthquake excitations. During the July 30 (M= 6.2) and the November 15 (M= 7.0), 1986 earthquakes, which occurred in Eastern Taiwan, a total of 16 pore pressure responses had been successfully recorded. Among the data obtained, 6 sets of data were the responses of 3 sensors triggered in both earthquakes. This data was selected to investigate the characteristics of pore water pressure responses during different earthquakes. It is found that the responses of pore water pressure are highly oscillatory during earthquakes. However, each of the pore water pressure records can be roughly divided into an initial build‐up stage and a following dissipation stage. During the build‐up stage, the pore water pressure responded in higher frequencies of fluctuation and the oscillatory parts were found to be best correlated to the wave trains of ground velocity in the vertical direction.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677479

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The Salmonella/microsome mutagenicity assay (Ames test) was based on the premise that bacterial assay systems provide an efficient way to detect the mutagenic activities of airborne mutagens and carcinogens. In routine work for detecting the mutagenic activities of airborne mutagens and carcinogens using the Ames test, the pretreatment of tremendous amounts of samples and the counting of revertant colonies can be labor‐intensive and time‐consuming.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677480

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Generally, most long‐range predictive control (LRPC) gives good set point responses in multivariable process control. However, on several occasions, little improvement in load rejection was observed when comparing LRPC with well‐tuned multiloop SISO controllers. In this study, the dynamic matrix control (DMC) algorithm is modified to improve disturbance rejection capability. A two‐degree‐of‐freedom DMC is proposed by incorporating the step‐response models for the major load disturbance. A load tuning factor is used to adjust the degree of load prediction. A non‐linear distillation column is used to test the effectiveness of the proposed algorithm. Simulation results show that, while maintaining good set point responses, the proposed algorithm outperforms the standard DMC algorithm for both the modeled and unmodeled load disturbances.

ISSN:0253-3839    

DOI:10.1080/02533839.1993.9677481

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor