摘要:

AbstractIn feedforward control systems, the output is made equal to the set point by measuring the disturbances in the input signal. This is in contrast to the common feedback control system where the error in the output is used to control the input to the system in order to get the output close to the set point. In practice, feedforward control is used in conjunction with feedback contro1.Feedforward control is generally used in systems with large time delays. This is the case with biochemical reactors used in Waste water treatment. It is desired to study a model of this system. Luyben (1) has done a similar study of reactors for the case of second order reactions.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759830

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractA mathematical model for the descriotion of the steady and the transient behavior of" a lithium bromide-water absorotion chiller is developed. This model is particularly important for the study of control requirements and is Convenient for the mathematical formulation of the control problem. Both a conceptual approach, that is, using the proper energy balance and heat transfer equations, and an empirical approach, that is curvefitting of the operating data, are used in develooing the model. The steady state part of the model is expressed as functions of the operating conditions (temperatures of the hot water input, the chilled water and the cooling water) and is derived by curvefits to the 0gerating data supplied by the manufacturer. The transient Dart of the model is expressed as a set of differential equations and is formulated by making use of the basic eyua Lions of energy and heat transfer. Finally, the derived model is used in the simulation of the chiller for different variations in the input hot water temperature and the results are compared with some available experimental data.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759831

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractAn investigation of the behavior of metals during asixymmetric extrusion using the finite element method is presented. Flow characteristics as functions of die shape. die-workpiece interface friction. die reduction ratio, and billet position within the die are determined under the assumption of fully plastic flow. An eight node isoparametric quadrilateral. finite element was used with the velocity and pressure fields approximated within the element by quadratic and linear interpolation polynomials respectively. The constitutive equations relating strainrate components to deviatoric stress components were of a form representative of a non-Newtonian fluid with stress-strain rate properties for SAE 1045 steel and 2017 aluminum alloy used in the study. Conical, cosine, hyperbolic and elliptic die shapes were included in the study. Friction at the die-workpiece interface was simulated by specifying a shear force tangent to the interface. The evolution of the extrusion process from the time the billet first enters the die until the extruded member exits the die WaS performed by solving a sp.quence of problems in time. Results of the various analyses include velocity and pressure fields together with the strainrate and stress distributions within the material.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759832

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

ResumeCette communication aborde certains aspects du probléme de La synthése de structure articulées en robotique.Les problémes rencontrés pour les systèmes actuellement en fonctionnement sont dus souvent, a la complexitéde résolution de leurs modéles cinematiques et dynamiques. Nous proposons dans ce travail, l’etude et la conception d'’un sysceme articule a six degrés de liberte, possédant des propriétés cinématiques et dynamiques intéressantes.Le modéle cinématique admet une solution quelle que soit la configuration articulaire du robot dans l’espace. Ceci impliquc l’absence de configurations singulieres qui compliquent la resollltion du modele. Le modéle dynamique obtenll a permis de demontrer la possibilitéde reduire Ie nombre de parametres dynamiques figurant dans les equations et de minimiser les couplages sOllvent importants encre les différences articlIlations.La simulation de ces deux modéles a conduitàdégager l’importance de ces avantages pour la réalisation d’une commande dynamique en temps-réel.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759833

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

ResumeIn the framework of power system studies, investigations on synchronous generators are of particular concern since the machine behaviour greatly affects the overall system performance. In this connection, generator models must be provided and proper parameter identification techniques suggested in order to make the models suitable to describe the actual responses with a good accuracy degree. An equivalent circuit approach is suggested in the paper; proper lumped circui t models are assumed for the direct and quadrature axes and, on the basis of frequency response data, an improved identification technique of the model parameters is proposed.The procedure is applied to a 107 MVA turbogenerator which has been SUbjected to extensive frequency response testings in connection with ANSALDO and ENEL (Italian Electricity Board) under a joint university/industry research project.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759834

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractA numerical code of modular type is described to evaluate the intensity and spectral profile of the radiation emitted by a laser-produced plasma. The spectral profile is evaluated by taking into account local broadening and shifting mechanisms of the natural lineshape, optical opacity and plasma streaming velocity. The code is designed to describe a fairly broad range of geometries and plasma conditions and can include different types of spectral line functions for the modeling of the local profiles. Examples of the functionning of the code are presented and discussed.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759835

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractLe maintien de la itabitiZe. du, gioupu touAnanti de gnan-dei dimensions des centralei nucleaires impose. la conception de nouveaux régulateurs. Partant d’un modéle non Linéaire da la turbine, nous avotu construit un modéle Linéaireàquatre variableis d’étatéduquel nous avons déterminéune régulation modale de vitesse.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759836

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractDesigning high-voltage insulation it is a main prohlem to determine the withstand voltage and the minimum life time. As a rule extrapolation hased on experimental mean values and variances (e.g. Three-Sigma Law) is used for determining the respective voltage level or life-time. For practical reasons only a limited numher of voltage tests may be carried out. Therefore the experimental results of small sample sizes are only the most probable inference of the actual values. Given a normal or transformed normal distribution of the measured values diagrams of the tolerance limits for the actual withstand voltage and minimum life-time have been developed using the non-central t-distribution. The application of this stochastic modelling technique permits a much preciser determination of the tolerance limits than the Kolmogorov-Smirnov goodness of fit test or conventional worst case design based on the central-t and Chi2-distribution.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759837

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractThe surface energy balance of lakes determines the evaporation.Parameterisations of the contributed heat fluxes allow the computation of the water temperature from meteorological data of the surrounding areas.Application to Lake Chad for the Sahel Drought shows the influence of the incoming solar radiation,the wind speed, the air temperature and the humidity on the decrease of the water level during that period.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759838

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

AbstractGeneralised equations are developed to describe the mean temperatures of a solar collector and storage tank in terms of the parameters of the system and the environmental conditions. Expe-rimental results are in good agreement with theoretical values for a small system tested on a solar simulator.

ISSN:0228-6203    

DOI:10.1080/02286203.1983.11759839

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor