摘要:

A unit-distance cyclic-code multiphase pulse generator is described. The generator is shown to possess a number of advantages over the better-known techniques using binary counters, ring counters and feedback shift registers.

DOI:10.1049/piee.1967.0031

出版商:IEE    

年代:1967

数据来源: IET

摘要:

In coincident-current ferrite-core stores, there is a particular pattern of stored information associated with any core which gives a large δnoise signal when that core is read out. Patterns very near to this worst-case pattern also give unwanted δnoise, and this paper calculates the average frequency with which a particular pattern occurs against its nearness to the complete worst-case pattern. For randomly operated 642planes the complete worst-case pattern occurs very rarely, and hence the large δnoise associated with it is rarely encountered. However, lower δnoise voltages from less complete patterns occur significantly often. The mean frequency of occurrence of a particular δnoise is plotted against its magnitude, expressed as a fraction of full worst-case δnoise. In 322and 162planes, complete worst-case patterns occur more frequently. The δnoise voltages associated with them may be expected to occur significantly often, if the planes are randomly operated. A complete worst pattern may also be disturbed in the worst possible way, creating an ‘absolute’ worst-case pattern, which would give the maximum possible δnoise. This is an extremely rare event, for any of the commonly used plane sizes, and even an incomplete absolute worst-case pattern, with half the cores arranged to give little δnoise, is still extremely rare for all but 162planes.

DOI:10.1049/piee.1967.0032

出版商:IEE    

年代:1967

数据来源: IET

摘要:

The topological properties of networks containing resistors, capacitors, self inductors and controlled current generators are considered. A restriction is found on the positioning of such generators so that the network may have a solution. The determinant of the node-admittance matrix of such a network is expanded in terms of some tree-admittance products. The order of complexity is related to a particular tree associated with such an expansion, and a method of calculation is given. It is shown that, for a broad class of networks, the order of complexity can be calculated by considering only the simplerRLCsubnetwork.

DOI:10.1049/piee.1967.0033

出版商:IEE    

年代:1967

数据来源: IET

摘要:

For an idealised model of a fix obtained by a network of direction finders on a narrow baseline, it is shown that the major axis of the probability ellipse is decreased, and the minor axis is increased, when positive correlation is present between bearing errors. The area of the ellipse is increased if there are three or more bearings, and the correlation is small.

DOI:10.1049/piee.1967.0034

出版商:IEE    

年代:1967

数据来源: IET

摘要:

The difference in the signals returned from two tetrahedral corner reflectors 6.9km apart along the same line of sight has been used as a measure of the attenuation of 8.6mm radiation in rain. Eight recording rain gauges along the line provided an estimate of the rate of rainfall. The relationship between the attenuation and the rate of rainfall was found to beAdecibels per kilometre = 0.26(5)Rmillimetres per hour. Mean values ofAover tens of minutes ranged from 0.20Rto 0.39R. The relationshipA= 0.265Rwas used to estimate the rainfall from the measured attenuations along the path. Only six of the 23 estimates of the rainfall total fell outside the range 80% < radar rainfall/gauge rainfall < 120%. However, as a practical means of measuring rainfall, the method would be restricted to light and moderate rains, since, in heavy rain, the signal would be attenuated to below the minimum detectable level, except over very short path lengths.

DOI:10.1049/piee.1967.0035

出版商:IEE    

年代:1967

数据来源: IET

DOI:10.1049/piee.1967.0036

出版商:IEE    

年代:1967

数据来源: IET

DOI:10.1049/piee.1967.0037

出版商:IEE    

年代:1967

数据来源: IET

摘要:

Methods for the calculation of the propagation coefficient of a rectangular waveguide containing a centrally placed semiconducting film are discussed. Numerical solutions for such a system with film resistivities in the range 10Ω–10kΩ/square and frequencies in the range 8.4–12GHz have been made, and confirmed experimentally at 9.25GHz. The theoretical results indicate the possibility of constructing waveguide flap attenuators with high attenuations and very small phase shifts.

DOI:10.1049/piee.1967.0038

出版商:IEE    

年代:1967

数据来源: IET

摘要:

Although there has been active interest in static relays for more than 20 years, it is only with the advent of modern semiconductors that appreciable progress has been made. The increasing performance required of modern protection is reaching the limits of capability of electromechanical relays, and practical development of static protection with higher performance and greater potentiality is becoming increasingly necessary.The paper surveys the broad approach to the development of static protection, the bases of design, the selection of components and the assessment of environmental conditions, all of which are important in producing equipment suitable for manufacture and having the performance and reliability associated with power-system protection. Typical examples of practical equipment are given to illustrate the various approaches and views expressed in the paper. The possible influence of static protection on associated equipment is discussed, and some future trends are predicted. Finally, the present state of development is assessed as being reached mainly by the work of manufacturing organisations, and the view is expressed that further development will require increasing participation by prospective users.

DOI:10.1049/piee.1967.0042

出版商:IEE    

年代:1967

数据来源: IET

摘要:

For many years, the maximum temperature power-transformer insulation would withstand was regarded as fixed, and was used as the basis of standard kVA ratings and of overload calculations. Later, the life of the insulation was found to be a thermal-aging process; so the maximum permissible temperature now became a variable with time. The derived aging formulas and the parameters in present use, together with the resulting standard overload values, are reviewed. Practical life studies to set bounds to the permissible temperatures have not been successful; so only relative conclusions can be drawn, and the absolute limit is still unknown. It is, however, clear that quite large margins are available over present-day practice, and some part of these have been incorporated in the more recent loading guides. The desirability of increasing present ratings to utilise these margins is considered. Analysis suggests that any extra rating thus derived cannot be economically realised and is better reserved for emergencies. It is concluded that loading capacity is not the only, or even the major, factor in determining the expectation of life of a transformer. There are other, more exigent, limits. Nevertheless, for practical-operation purposes and to permit systematic planning, a standard loading practice, however arbitrary, must be established. The national loading guides fulfil this function in a relatively simple and practical manner. In particular operating conditions where the loading requirements can be more closely prescribed, it is possible to work directly on the hottest-spot temperature and dispense with some of the orthodox restrictions. The ‘integrated system transformer’, to which brief reference is made, is the first practical application of this principle.

DOI:10.1049/piee.1967.0043

出版商:IEE    

年代:1967

数据来源: IET