摘要:

Discrete event dynamic systems are frequently encountered in complex man-made systems. Such a system is often described in terms of a timed Petri net. For periodic behaviour of such a system, a timed marked graph provides a convenient and powerful tool of modelling and analysis. In this paper we define three optimization problems for such a system. All of these problems are formulated as mixed integer linear programming (MIP) problems. To improve computational efficiency, we introduce ‘cuts’ to these MIP problems, and the effect of such cuts is examined through computational experiments on some test problems.

ISSN:0020-7721    

DOI:10.1080/00207729408949356

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this paper an autoregressive model is proposed for the form and movement of a fish school swimming in a circular water tank. The form of the fish school is assumed to be an ellipse. The major and minor axes of the ellipse and the displacement angle of the school centre are used as the variables for the model. Using the observation data from a water tank experiment, the model parameters are estimated. The very low frequency components of the data are removed by using a smooth integrated random walk model. The validity of the model obtained is examined by a whiteness test of the residual.

ISSN:0020-7721    

DOI:10.1080/00207729408949357

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The problem of lot sizing and scheduling of production runs for multiple products to be processed on a machine was studied. The problem is formulated as a dynamic system, for which we show that cyclical schedules with the clearing lot sizing rule leads the system to a steady state. In the steady state we obtained a closed-form formula for the cycle time, the lot size and the maximum inventory level for each product. Finally, we showed that the clearing lot sizing rule is the optimal linear lot sizing rule that minimizes the system's inventory levels in the steady state.

ISSN:0020-7721    

DOI:10.1080/00207729408949358

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper presents a procedure which allows the exact retention of poles and/or zeros in a reduced-order model while the rest of the coefficients are calculated by means of least-squares matching of Padé coefficients and Markov parameters. The exact retention of poles and zeros is desirable in some situations as a means to usea prioriinformation to determine the simplified model, and thus provide some physical links with the original system. Moreover, the stability of the reduced-order models is guaranteed, although unstable poles and non-minimum phase zeros may be retained if required. On the other hand, least-squares moment-matching is advantageous because extra dynamical information is included in the final model and a family of models of the same order may be readily computed. In this paper the H∞ norm of the error is used to select the best individual from a family of models. The importance of retaining dominant poles and zeros, as well as how to recognize truly dominant poles, is also addressed in the paper. Three numerical examples illustrate the new procedure.

ISSN:0020-7721    

DOI:10.1080/00207729408949359

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The authors' objective is to simulate a steam-generating system when the real parameters of the process can be measured only at a few locations. In this context it is necessary to define a functional structure and to model the longitudinal distribution of the physical phenomena. To reconstruct the real parameter distributions, it is necessary to take into account the heat and mass balance equations. These equations are elaborated with the help of a control volume. The resulting models of the transportation and transformation elements are used as a first step to define the system concept. Part 2 will be devoted to the numerical simulation.

ISSN:0020-7721    

DOI:10.1080/00207729408949360

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An aggregative simulation system that uses the time-slicing method to obtaining the numerical responses of complex mechanical system (CMS) is described in this paper. This class of system is represented by a few procedures: communication, calculation, visualization, linking and structure mapping. Some of these procedures have been used to estimate distributed controls of the steam-generating system (SGS). For the case in which both calculation and visualization processes are used, these control (input) profiles show which element of the SGS is more disturbed by means of an arrow. To memorize the local disturbance, a calculated window has been used in which it is possible to show some numerical and graphical characteristics of all the elements of a CMS. To complete the numerical simulation of a CMS, a general example is worked out to show how this simulation system helps to select some operating conditions of all the elements of SGS.

ISSN:0020-7721    

DOI:10.1080/00207729408949361

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The notion of entropy, which is known from information theory as a measure of uncertainty of the data on security returns, is used to illustrate by examples how the traditional optimal portfolio models may be suitably reformulated.

ISSN:0020-7721    

DOI:10.1080/00207729408949362

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor