摘要:

AbstractThe periodical variations of speed caused by the nonuniform torque of the prime mover can provoke dii ferent troubles in the isolated networks. The problem is particularly serious for what concerns parallei connected generators driven by diesel engines as in ships.The aim of this study is the transient analysis of two parallel 1iesel-alternator sets for power supply in ships.In this paper the problem is faced by means of simulation; the diesel engine nonuniform torque, taken as disturbance for the model, is evaluated under different conditions.Some remarks on the forced oscillations are presented and the influence of alternator damper winding is evaluated in a significant condition.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759807

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractWe present the preliminary results of a project concerning the modelling of the primary air heat exchange system for a coal-fired 250 MW power plant.The aim of the project is to develope a linear mathematical model in order to study the dynamics of the system based on simulations.Transfer functions for the heat exchangers have been direived and incorporated into the total simulation model. Computed transient responses to a step in plant load are presented.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759808

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractThe determination of the efficiency of a gross human movement requires apppoppiate techniques for the measurement of both energy expenditure and musculap work. Under certain conditions, energy expenditure is peadily obtained from measurements of total body oxygen consumption, and movements may be pecopded cinephoto-graphically, but while a vapiety of methods have been used to determine the mechanical work done during locomotion no satisfactopy wopk-energy model of vigorous activity currently exists.Early studies of movement efficiency which were based on point-mass models of the body have mope recently been followed by systems in which the body is modelled as a series of linked pigid segments. While the segmental models provide a more detailed analysis of the mechanical energy transformations during movement some important energy components have not been included. In papticular the temporary storage are subsequent release of Strian energy by muscle and tendon tissue have been ignored.This paper critically discusses the model systems that have been used to evaluate mechanical energy changes in the human body with particular reference to expepimental studies of punning, and enhancements to the work-enepgy model are proposed.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759809

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractIn this work we determine a mathematical model of a possible practical realization of the drive effecting the method of speed control of an asynchronous three-phase motor, based on the chopper control, here defined as“nonsynchronous”control, of the rotor currents performed simultaneously on the three phases at sufficiently high and constant frequency, and independently of that of the rotor currents.In particular, a procedure is described for obtaining a mathematical model of the drive in question, which makes it possible to generate automatically all conduction configurations that depend on the ON-OFF state of the semiconductor elements present in the static converters, thus obviating both a priori identification of these configurations and determination of the corresponding differential equations.This approach is of general validity and can be utilized for the study of drives, which consist of d.c. or a.c. motors and static converters.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759810

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractThis work consists of a theoretic and experimental study of a possible practical realization oi the drive effecting the method oi speed control of, an asynchronous three-phase motor, band on the chopper control, here de-fined as“nonsynchronous”contAol, oi the total currents petioimed simuttaneously on the three phaiei at suiii-cientlij high and constant irequency, and independently of that of the rotor currents.In particular, by means of implementation of a mathematical model of the system as a whole, a theoretic. Study is carried out of its static behaviour and of that of the dynamic behaviour of a closed-loop control system. A de-scription is then given of equipment permitting control of the asynchronous motor according to the method in ques-tion; the experimental results obtained through this equip-are presented and compared to those obtained tlieoretically.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759811

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractIn this paper the authors present the application of a decomposition-coordination method to the static optimization of a topping unit in order to minimize the energy consumption. The topping unit is divided in two subsystems: the atmospheric column and the heat train. Each subsystem minimization problem is solved by gradient algorithms. The overall minimum is obtained by a prediction type coordination algorithm. The algorithm structure used is a sequential solution type.Industrial applications are included.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759812

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractVariation in the quality of solid fuels cause difficulties in the control of power plants because the heat power of the fuel flow may vary remarkably. For example in a peat power plant the heat value of the fuel can vary from 1200 to U600 MJ/m3. If we want to stabilize the burning process and the heat power released through combustion we must know the heat value of the fuel to be able to control the fuel feed precisely. However there exists no on-line measurement for the heat value.The estimation of the heat value of the fuel can be carried out by measuring the oxygen content in the flue gases and calculating the oxygen amount used in the combustion process. The oxygen consumption correlates accurately with the heat power released in the combustion. The flue gas oxygen content should be measured with a fast ZrO2in-situ oxygen sensor. To estimate the heat value a model for fuel feed, combustion and oxygen measurement is constructed. A Kalman type estimator has given excellent results when tested with measurement data from the biggest Finnish pent fuelled power plant. Also a new control strategy based on oxygen consumption is developed.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759813

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractLe séchoir est une colonne verticale contenant le mais. L’air de séchaae est distribuépar des canaux noyés dans la masse de grainàdifférents niveaux de la colonne. Le grain sec est soutirépeériodiquement en bas de l’appareil et circule par gravité.Le modéle est constituéd’une part, deséquations de bilan entre l’air et le qrain, et d’autre part d’une loi empirique du séchaae du maisétablie au laboratoire,àpartir d’experimentations de séchane en couche mince. La déformation du Droduit au cours du traitement est prise en compte ; toutefois, la simnlicitédu modèle permet d’effec-tuer les calculs au moyen d’un nicroordinateur.Les résultats des simulations ontétévalidés sans ajustement par une campagne de mesure faite sur un sechoir industriel ; la comparaison entre mesure et calcul porte sur la température de l’air sortantàdifférents niveaux de la colonne et sur la teneur en eau du maisàI’entrée etéla sortie de l’appareil.Les paramètres de construction (dimensions, nombre et niveaux des entrées et sorties de l’air) peuventétre choisis ainsi que certains paramétres de fonctionnement (température de l’air d’entree en fonction du niveau, débit d’air, frequence des soutiraqes et quantitéde grain sou-tiréàchaque fois) en vue de la comparaison de diverses conceptions et modes de fonctionnement de séchoirs.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759814

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractUne simulation paralléle de la méthode de GEAR [6] pour résoudre un systéme d’équations algébro-différentielles est décrite. Nous avons obtenu un gain appréciable du temps d’exécution De nouvelles conditions pour assurer la stabilitéd’une méthode a pas liés sont présentées. Ces conditions permettent de déduire deux formules d’ordre deux et trois qui ont une erreur de troncature trés faible, ce qui nous donne un autre moyen de diminuer le temps d’exécution.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759815

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractThe paper describes different mathematical models and real-time predictors of the short-term winter electric load in the biggest Italian district. First it is ascertained that weather variables such as temperature and illumination actually affect the load. Their maximum impact is quantified in 6% in a winter workday. However, when forecasting the load in real time, the use of the exogenous weather inputs can be surrogated by a careful modelling of the autoregressive predictor component and by applying recursive parameter estimation techniques like exponential weighting.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759816

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor