摘要:

AbstractVoltage sags of limited time duration are one of the most serious impediments to power supply quality, because of thepossible consequence for the performance of electrical appliances. Among the possible solutions to the problem of voltage sags on either the side of the utility or on the side of the customers' power systems, a particularly promising solution appears to be the use of static booster devices with no primary energy storage. In fact, a majority of the sags are not outages, and there is still a residual voltage present at the delivery point of the net during the transient. This voltage can be adequately boosted if a suitable, very fast response, simple and inexpensive device, able to sustain the customer's bus-bar voltage, can be made available. This paper deals with the above topic and discusses in detail how this target can be achieved. Two type of static boosters, a continuous action and a step-by-step static booster, are described and compared. The relevant modelling and digital simulation results, referred to particular case studies, are also reported and discussed.

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760222

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractOne of the major problem for the identification of industrial multi-input muti-output (MIMO) systems is the too smallvariance of some signals collected during several experiments. Usually, sufficient information exist but are often dispersed among many data-files. In this case, it is difficult to conciliate this information to build a single well adapted model. The ALS procedure (Alternate Least Squares) has been performed in order to solve this kind of problem. In the first part of this paper, the authors present the principle of the ALS procedure ; the details of the complete algorithm are given in part two. Then, based on some examples, a comparison of the Prediction Error Method (PEM) with our new methodis presented.

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760223

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractIn this paper, flow characteristics are obtained by using the penalty function finite element method with the balancing diffusivity upwind scheme to solve the governing Navier-Stokes equations. The shear stress along the lower wall behind the bluff body is compared with the available experimental and numerical results for various factorized time steps. The reattachment length and pressure drop are also presented for a full cycle. The pulsating flow acts as a cyclic iterative effect on the channel and its wall. The results may explain some local phenomena that frequently occur in the field of bioengineering.

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760224

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractIn this article, three complementary thermal models of welding with material transfer are developed and evaluated. First, a lumped analytical model of the weld bead geometry integrates separate closed- form formulations for the compositeconduction field in the solid area, the double-stream circulation in the weld pool, and the torch distribution. Second, a numerical simulation of the temperature and phase field in an Eulerian control area allows for multiple-torch welding configurations. Last, a nonstationary, linearized experimental model in the form of a dynamic transfer matrix relating the weld geometry to the torch distribution provides the basis for real-time estimation of the process parameters. This in-process identification is finally employed in a multivariable, adaptive thermal control system, and its performance istested in simulation, in combination with all three models of the welding process. Experimental testing of the control system is reported elsewhere.

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760225

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThe performance of nonadaptive and adaptive routing algorithms and the combined effect of a multilevel flow-control mechanism in different topologies of a wide-area packet-switched network is studied by means of simulation. Communication systems with the datagram switching technique are considered.

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760226

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractSimulation analysis can reduce the costs and risks of operations by using mathematical representations of real-world problems and solving them by computer. Simulation modelling addresses manufacturing issues that will help management make basic evaluations of the different options and do sensitivity tests to evaluate "what-if" situations. It enables the modeller to measure the performance of the existing or proposed systems under different operating schemes. Simulation of the operation of a system has rapidly become one of the most useful and common applications of computers. Along with theprevailing use of simulation has come a great deal of misuse. Underlying all such misuse is lack of knowledge. A simulator is only as sound as the techniques used in constructing it, and the validity of the results gained from a simulation is influenced by such factors as the techniques used in the collection of data and the analysis techniques used in summarizing the data. Hence, not every simulation output will represent the real system. This article is first of a series onthe subject of simulation technology. In this article the process of simulation modelling, data collection, common pitfalls in simulation modelling and its implementations, and training requirements are described.

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760227

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThe authors examine several strategies for the allocation of container yard equipment in terms of container handling throughput,equipment utilization, and waiting times. Data from a large container yard in Hong Kong are used in a case study. The study helped to improve the day-to- day operations efficiency of a container yard by providing insight into theeffect of various yard equipment allocation strategies during periods of peak workload.d

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760228

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractIt is well known that when the sensor is collocated with the actuator stable, behavior can be achieved with simple control structures. This is not the case for lightweight flexible manipulators, where noncollocated sensors have to be present in order to achieve faster and precise response without considerable vibration. The need for parameter estimation and/or adaptive control of this system arises because of lack of knowledge of the values of important internal parametersand their variations under different load conditions. In this work we present an on-line recursive identification algorithm to determine the main relevant parameters of a single-link flexible manipulator. Different input excitation signals are studied in combination with prefiltering techniques to improve the convergence of the algorithm. The objective of this work is to obtain an identification scheme reliable enough to be implemented on-line for high-order systems

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760229

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor

摘要:

AbstractThe present work examines an additional approach to regression analysis by introducing the Relative Least Squares technique to model fitting. In addition to the usual Mean Square Error (MSE) criterion, an Average Relative Error (ARE) criterion is introduced as a measure of model performance of its estimators. Furthermore, a model adjustment technique is presented in order to reduce the ARE of estimators. Finally, a simulation study involving data from four different distributions is used to compare Least Squares (LS), Relative Least Squares (RLS), Least Absolute Value (LAV), their adjusted Equivalents, and Minimum Relative Error (MRE) estimators. For normally distributed disturbances, Least Squares and Relative Least Squares procedures are recommended; however, for heavy tailed disturbances the adjusted LAV procedure seems tobe superior.

ISSN:0228-6203    

DOI:10.1080/02286203.1994.11760230

出版商:Taylor&Francis    

年代:1994

数据来源: Taylor