ISSN:0143-2087    

DOI:10.1002/oca.4660090302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper deals with an approach to the problem of spacecraft trajectory optimization that has been successful on a wide range of practical examples. A particular group of missions involving low‐thrust solar‐powered vehicles has presented difficulties for the method, however, and these are described and discussed. In particular the problems seem to reveal weaknesses in some current algorithms for constrained minimization, and we therefore consider some new optimization routines. We also derive a new formulation of the problem using eccentricity and momentum vectors as state variables rather than the more usual Cartesian co‐ordinates. This reformulation allows us to make some simplifying assumptions which make the problem easier to solve while still furnishing good estimates of the true op

ISSN:0143-2087    

DOI:10.1002/oca.4660090303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA monopolistic firm is considered that can choose between two production activities: a capital‐intensive one and a labor‐intensive one. The successive stages of evolution of the firm are discussed for several alternative formulations of the objective functional. The effect of a minimum employment constraint is investigated and other sensitivity results are provi

ISSN:0143-2087    

DOI:10.1002/oca.4660090304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractAn application of a linear quadratic self‐tuning control approach to a pulsed liquid‐liquid extraction column is described. The control algorithm is derived from the minimization of a quadratic cost function. The resulting Riccati equation is iterated until the closed‐loop poles belong to a predefined stability domain included in the unit circle. Based upon the certainty equivalence principle, the adaptive control algorithm involves a parameter identification procedure and a feedback control law which uses the estimated parameters.Several experiments are carried out on a pulsed liquid‐liquid extraction column. Such extractors are being increasingly used in several industries because they are not energy‐consuming and they lead to high product purity. The column considered has the same dimensions as those currently used in fine chemical processes. The control objective is to optimize the column behaviour. The selected control variables are the pulse frequency and the conductivity measured at the bottom of the column. The experiments have been carried out with a mixture of water and toluene. The physical model developed for the column is too complex to use for control purposes. To represent the complex behaviour of the column, a single‐input/single‐output discrete‐time linear model was adopted. The parameters in the model are estimated on‐line with normalized data. The forgetting factor is also adjusted to maintain a constant trace of the estimator gain matix.The results obtained show the ability of this algorithm to improve the efficiency of the process considered. Finally, some details on practical implementa

ISSN:0143-2087    

DOI:10.1002/oca.4660090305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractCandidate fuel‐optimal trajectories for rendezvous in space are obtained with a parameter optimization method. These trajectories, which may include a minimum radius constraint, are verified against necessary conditions for optimality. Necessary conditions are presented in the form of requirements on aprimer vectorand in terms of requirements on the jumps in the costates when the constraint is encountered. In addition, criteria due to Lion and Handelsmann indicate how to improve candidate trajectories which prove non‐optimal so that they become locally optimal. Numerical results are presented which show that the candidate solutions must be obtained to a high level of accuracy before primer vector tests are va

ISSN:0143-2087    

DOI:10.1002/oca.4660090306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractMethods for power network parameter estimation and correction are discussed in this paper. A sequential‐type method for real‐time processing of network parameters is proposed. The method exploits the information contained in the measurement residuals to estimate a better network parameter; it uses a linearized sensitivity model to relate the measurement residuals to the parameter error. The proposed method has been coded in FORTRAN using several short‐cuts and has been thoroughly tested in the estimation of transformer ratios in the Belgian HV s

ISSN:0143-2087    

DOI:10.1002/oca.4660090307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this work we consider various feedback controllers designed for linear stochastic‐parameter discrete‐time systems. These controllers are derived by use of different system models (true system model and its deterministic equivalent) and different performance criteria (infinite horizon and finite moving horizon) to stabilize the same class of systems. It is shown that sufficient conditions for almost‐sure and mean‐square stabilizability by these controllers are closely

ISSN:0143-2087    

DOI:10.1002/oca.4660090308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn a recent issue of this Journal, Lin1analyses a pollution control model that is designed to include adjustment costs, investment, employment and inflation. His analysis of the control theoretic solution appears to contain a number of errors which are pointed out below. Also, the model that he constructs has some awkward features in the view of this analyst. My concerns with the model are outlined in the second section of this comment.

ISSN:0143-2087    

DOI:10.1002/oca.4660090309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0143-2087    

DOI:10.1002/oca.4660090310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0143-2087    

DOI:10.1002/oca.4660090301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY