摘要:

One criterion which can be applied to the evaluation of the electrostatic design of high-voltage equipment is the ratio of the average to the maximum electric field. This may be termed the ‘utilisation factor’ η, and shows how inferior the arrangement is when compared with two infinite parallel-plate electrodes where η = 1.0. Tables of utilisation factors, calculated by means of a digital computer, are given for several standard electrode systems. η takes no account of the space necessary to accommodate the conductors; this can be done by deriving a related quantity λ, termed the normalised effective electrode separation. Values of λ and conditions for it to be a maximum are also given.

DOI:10.1049/piee.1967.0292

出版商:IEE    

年代:1967

数据来源: IET

摘要:

Measurements have been made of dynamic magnetostriction in 3%-silicon oriented magnetic sheet steel (Goss textured) under combined longitudinal and transverse stresses between 600Ibf/in2compression and 600Ibf/in2tension longitudinally, and between 600Ibf/in2compression and 400Ibf/in2tension transversely. It was found that the results obtained on many different samples could all be reasonably represented by a single master curve of magnetostriction against longitudinal stress with appropriate zero shift for each sample. This zero shift was then used as a figure of merit for the stress sensitivity of each material.Measurements were also made of static strain against mechanical stress. The stress/strain curves show nonlinearity due to domain movements. The shape of these curves was used quantitatively to support a theoretical explanation of the relations between the effects of longitudinal and transverse stresses on dynamic magnetostriction. The curves may also be significant for such purposes as calculation of core resonant frequencies.Double-phosphate-coated catenary-annealed steel was found to be less stress-sensitive than normal single-phosphate-coated roller-hearth-annealed sheet, and it was shown that the second phosphate coating was responsible for much of the improvement.

DOI:10.1049/piee.1967.0293

出版商:IEE    

年代:1967

数据来源: IET

摘要:

Different methods are described for evaluating the field distortion due to a radially symmetrical distribution of charges in a spark discharge between plane parallel electrodes. Poisson's equation is solved numerically using a relaxation procedure, and the results are compared with those obtained using less accurate methods, in particular the one-dimensional form of Poisson's equation. The application to the calculation of ionisation currents in gases between parallel-plate electrodes is discussed.

DOI:10.1049/piee.1967.0294

出版商:IEE    

年代:1967

数据来源: IET

摘要:

This paper outlines a method of determining axially symmetric field distributions, where the shape of the insulation involved tends to be complex. Finite-difference techniques form the basis of the method which is illustrated by examples. Programming methods to reduce labour, computing time and costs are outlined, and a flow diagram of the general program is given. Accuracy and time saving are indicated by comparing the computed field distributions between concentric cylindrical electrodes and rotational hyperboloidal electrodes with the exact analytical solution of these distributions.

DOI:10.1049/piee.1967.0295

出版商:IEE    

年代:1967

数据来源: IET

摘要:

A lumped-model representation for large distributed-process systems is considered, using simplified subsystem structures interconnected with delayed-output variables and controlled with delayed inputs. The formulation and control of such an overall multivariable system are studied using a state-variable representation, and techniques are developed for obtaining an optimal-control solution related to quadratic performance functionals. Simplified solutions based on a multilevel-type formulation of the extended-state system, and a multistage iterative process for incorporating the predicted optimal trajectory, are investigated. The methods are illustrated with the control of an interconnected sequence of second-order linear systems, containing output and control variable transport delays.

DOI:10.1049/piee.1967.0299

出版商:IEE    

年代:1967

数据来源: IET

摘要:

Linearised model-reference systems are used for integrating the controls of a nonlinear lumped-parameter boiler model. The model equations are based on mass and heat-balance, heat-transfer and momentum relations previously derived for the assumed sections of an actual operating oil-fired boiler.The study investigates the control of the process, represented by a set of nonlinear equations, using the structure of a linear model for generating an optimal sequence of discrete inputs with reference to a quadratic cost function.Integrated control related to the linearised models provides superior performance compared with conventional control of the system operating with step disturbances using suitably defined performance criteria. The results demonstrate the suitability of a linear model for control of the particular nonlinear system over relatively wide load levels. A reduced-order linear system also appears to be adequate for providing an integrated control structure, and would be suitable for forming the basis of an online adaptive digital-control system.

DOI:10.1049/piee.1967.0300

出版商:IEE    

年代:1967

数据来源: IET

摘要:

An attempt is made to define the initial conditions from which a Sun-pointing satellite with a simple on-off jet-control system is capable of acquiring attitude control. The control system was assumed to be stabilised by means of phase advance of the error signal rather than by the use of rate gyroscopes. The study was carried out mainly by digital computation.The maximum initial angular velocity from which satisfactory acquisition performance could be achieved increased with increasing available angular acceleration and fell as the inertia configuration was made more asymmetrical. The results are strictly applicable only to control systems of the type outlined above. Suggestions are made of alternative arrangements which might be worth study.

DOI:10.1049/piee.1967.0302

出版商:IEE    

年代:1967

数据来源: IET

DOI:10.1049/piee.1967.0303

出版商:IEE    

年代:1967

数据来源: IET