摘要:

An analysis is presented of a sampled-data parameter-adaptive control system. The accuracy in the region of optimum is seen to be adversely affected by fluctuations in the measured performance index owing to short-term smoothing. A normalised performance index is proposed to reduce these fluctuations. This index is largely insensitive to fluctuations in the control-system input. Its use also ensures that the gain of the parameter-adjusting loop does not depend on the amplitude of the control-system input.The parameter-adjusting loop, a stepping system, is incorporated in a digital computer. Provision is made for a dead space in the parameter loop to reduce the likelihood of false steps near the optimum parameter setting. A steady-state solution of the parameter loop equations indicates the dependence of parameter loop accuracy on step length, dead space and the variance of the performance-index fluctuation.

DOI:10.1049/piee.1964.0027

出版商:IEE    

年代:1964

数据来源: IET

摘要:

Methods used to test silicon solar cells are described, and an account is given of the effects on the battery-charging characteristics of having different numbers of high-output cells in series under different ambient light intensities. Outdoor evaluation tests indicate that an economical number of cells per storage cell is between four and five. Considerations are given to the design of cells for ground-level operation, where a long unattended life is important, and to the method of mounting; an angle of elevation between site latitude and site latitude + 15° is acceptable for many applications. A graph showing the average total insolation power available throughout the world is presented. In designing a solar-cell/battery power supply for a given application and site, use is made of these data in conjunction with monthly input-output figures for the chosen cell configuration. The battery capacity is chosen so that the excess charge produced in the summer at least equals the deficiency to be made up in the winter. The most recently developed cell will, under favourable conditions, produce electricity at about 1d./Wh, estimated for a five-year life. This is shown to compare favourably with conventional power sources operating at remote locations. The list of applications for solar-cell-generated power is constantly growing, and the conversion of various equipment from valve to transistor design is expected to give impetus to this growth.

DOI:10.1049/piee.1964.0028

出版商:IEE    

年代:1964

数据来源: IET

摘要:

The properties of iron disilicide (FeSi2) have been investigated, and it has been shown to be a semiconductor with a thermal energy gap of 0.88 ± 0.04 eV.It has been found possible to dope FeSi2bothnandptype by the substitution of suitable elements for iron and silicon. The doping mechanism is obscure since relatively gross quantities (2–5%) of dope are required to achieve optimum thermoelectric properties. Substitution of cobalt for iron yields ann-type material, and substitution of aluminium for silicon produces ap-type material. These materials haveZ> 2 × 10−4deg C−1over the temperature range 150–650°C.The materials are oxidation-resistant, thermally stable and mechanically strong.A method of construction is described which exploits the properties of these materials and should produce a cheap, robust generator of high power/weight ratio.

DOI:10.1049/piee.1964.0029

出版商:IEE    

年代:1964

数据来源: IET

摘要:

With the object of explaining the anomalous losses observed in thin ferromagnetic sheet, several authors have calculated those in an idealised material containing regularly spaced domain walls extending right through the sheet. These calculations are now extended, firstly to yield analytic expressions for the real and imaginary parts of the permeability which facilitate comparison of the theory with experiment, and secondly to include the effect of variable wall spacing, and stiffness. Extensions to include spin phenomena are also discussed.

DOI:10.1049/piee.1964.0030

出版商:IEE    

年代:1964

数据来源: IET

摘要:

Measurements are made of the initial permeability of iron and of certain high-permeability nickel-iron alloys over a frequency range extending to 30 Mc/s. The Polivanov-type eddy-current-loss calculations of Part 1 of the paper, intended to explain the eddy-current anomaly by considering a material with a magnetic-domain structure, are shown to be no more accurate than classical theory in predicting the behaviour of these specimens. In the thinnest Permalloys the high-frequency behaviour can be explained by a Snoek-type resonance phenomenon.

DOI:10.1049/piee.1964.0031

出版商:IEE    

年代:1964

数据来源: IET

摘要:

Spark reignition voltage characteristics have been measured for gaps between stationary electrodes for various controlled speeds of gas flow following d.C. pulsed arc discharges. By varying the gap geometry, electrode material and duration of the initial arc, the influence of both the gas flow and the electrodes on the detailed shapes of the characteristics have been determined and qualitatively explained. A crude theoretical approach is described, in which the variation of spark reignition voltage is satisfactorily accounted for in terms of the average gap density as controlled by the initial electrode heating, the time constants of the conductive cooling of the gas and the electrodes, and the heat transport by the gas flow through the gap.

DOI:10.1049/piee.1964.0032

出版商:IEE    

年代:1964

数据来源: IET

摘要:

Switches for fusion experiments are required to discharge energy-storage capacitor banks, charged to voltages up to 100 kV, and to pass currents of 50 kA to 2 MA. The characteristics of various types of switch are considered, and detailed descriptions are given of several switches in which the current is passed as a low-pressure gas discharge.

DOI:10.1049/piee.1964.0033

出版商:IEE    

年代:1964

数据来源: IET