摘要:

This paper presents an extension of recent results reported by Reiser and Kobayashi to semiclosed queueing networks with multiple semiclosed chains. The results have direct application to the analysis of computer-communication networks with end-to-end and/or isarithmic flow control.

DOI:10.1049/piee.1979.0052

出版商:IEE    

年代:1979

数据来源: IET

摘要:

This paper describes an analytical approach using a step-by-step method to calculate and explain the reasons for the long time delays associated with direct current in convertor transformers. The paper also shows the results of tests carried out on model transformers and discusses the close agreement between the two sets of results.

DOI:10.1049/piee.1979.0053

出版商:IEE    

年代:1979

数据来源: IET

摘要:

Connection of the Dinorwic pumped storage station in Snowdonia to the 400 kV supergrid is to be made by two 400 kV cable circuits rather than by overhead lines because of the outstanding natural beauty of the area. The cables have 2500 mm2copper conductors, oil-filled paper insulation and aluminium sheaths and will be cooled by circulating water in high density polyethylene pipes laid with the cables. Part of the cable route chosen runs along a narrow strip of land adjacent to the lower lake, and the system has been designed to transmit the peak demand of 2340 MVA through two circuits occupying a width of 2.1 m. The paper describes the design of the cables and of the water-cooled accessories and the tests to which they were subjected. The cooling-station designs are also described and the special methods of laying and jointing the cables in the restricted space available.

DOI:10.1049/piee.1979.0054

出版商:IEE    

年代:1979

数据来源: IET

DOI:10.1049/piee.1979.0055

出版商:IEE    

年代:1979

数据来源: IET

DOI:10.1049/piee.1979.0056

出版商:IEE    

年代:1979

数据来源: IET

摘要:

An adaptive control scheme, with low computational requirements, applied to controlling the excitation of a synchronous generator is described in this paper. The adaption scheme adjusts the feedback gains of a linear controller to minimise the errors between the terminal voltage of the machine and its reference value. Minimising these errors over the time period corresponding to one cycle of normal machine oscillations results in highly desirable damping characteristics. Computer simulations are used to compare the response of the adaptive controller with that of a conventionally controlled machine.

DOI:10.1049/piee.1979.0063

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The inclusion of a gradient load, as a fixed but arbitrary function of distance travelled, is investigated within the design of an optimal controller for electric traction drives. A successful approach is shown to involve (a) the sub-division of a journey intoNpiecewise constant-gradient stages, (b) the interative solution of the state and costate system equations at each stage transition and (c) the use of general dynamic programming to optimise the overall journey with respect to the initial velocities and subsequent stage times at each transition. Step (b) is achieved utilising a sensitivity model for initial costate iteration based on analytic zero-gradient solutions. The iterative scheme is shown to be stable for all conditions other than large downhill gradients, reverse-time integration being necessary under such circumstances. The minimisation of the combined mechanical and electrical energy losses is advocated and savings from 15 to 25% are demonstrated.

DOI:10.1049/piee.1979.0064

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A noncontact method is described for measuring the speed of steel strip to an accuracy of about 0.1% over the range of speeds typically found in steel mills. The method is magnetic in character and relies on the presence of a small amount of hysteresis in the material of the strip. A wavelength-sensitive reading head of multiple construction detects magnetisation along the strip and is connected in a feedback configuration to a writing head placed upstream of the reading head. With sufficient amplification, an unstable system results, oscillating at a frequency approximately proportional to the strip speed. Phase shifts within the feedback loop cause a departure from linearity in the speed/frequency relationship, an effect minimised by a further feedback loop which performs phase correction.

DOI:10.1049/piee.1979.0065

出版商:IEE    

年代:1979

数据来源: IET

DOI:10.1049/piee.1979.0067

出版商:IEE    

年代:1979

数据来源: IET

DOI:10.1049/piee.1979.0068

出版商:IEE    

年代:1979

数据来源: IET