摘要:

In November, 1939, the order was given to degauss all ships by coiling. This decision was taken after a coil had been tried on a ship at Portsmouth and proved effective against the original German magnetic mine. Mass treatment of this kind immediately showed many difficulties. In fact, study of the problem had merely begun and very much investigation was required before it was possible to make degaussing effective against the much more sensitive mines which were laid from 1941 onwards. This paper surveys briefly the study of the magnetic fields of ships made during the war, and indicates how coils were placed to neutralize them.

DOI:10.1049/ji-1.1946.0150

出版商:IEE    

年代:1946

数据来源: IET

摘要:

The paper covers the development of degaussing of warships and merchant ships from the electrical engineering aspect. Early temporary D.G. installations consisting of cables clipped on deck are described, followed by detailed accounts tracing the evolution of the various permanent systems of degaussing, from the first external copper-strip coils energized from low-voltage motor-generators, to the latest high-voltage, resistance-regulated systems of internal multicore-cable coils, incorporating automatic course-correction equipment controlled by the ship's gyro-compass system. The type of cable for the coils and methods of jointing used on the different forms of D.G. installations are outlined. A description of the D.G. equipment on one of the latest battleships is also included.

DOI:10.1049/ji-1.1946.0151

出版商:IEE    

年代:1946

数据来源: IET

摘要:

As an alternative measure to coiling certain vessels for their protection against mines, processes known as “wiping” and “flashing” have been used. The process known as “deperming” has been developed to remove or compensate the permanent longitudinal and athwartship magnetisms, which frequently lead to dangerous fields even in the case of coiled vessels. These three processes are separately described, and the various techniques which have been employed are briefly discussed. Particular attention is paid to the methods developed for ensuring the maximum stability for the treatment.

DOI:10.1049/ji-1.1946.0152

出版商:IEE    

年代:1946

数据来源: IET

摘要:

The necessity for compass-corrector equipment is explained, and it is shown how this was developed after it had been ascertained that D.G. coils produced a linear effect at the compass position.The correction was applied by means of air-cored coils attached to the compass binnacle, and supplied with voltage proportional to the current in each D.G. coil.The corrector coils were arranged to correct three mutually perpendicular components of magnetic field.A brief indication is given of the methods adopted for minimizing compass troubles caused by “wiping” and “flashing.”

DOI:10.1049/ji-1.1946.0153

出版商:IEE    

年代:1946

数据来源: IET

摘要:

The intrinsic electric strength of certain solid dielectrics has been measured for comparison with theories of electronic breakdown and on account of the bearing on industrial applications of dielectrics.Attempts to measure the strength of paraffins were unsuccessful, except for material oriented by pressing, because of the poor mechanical properties of such substances.Satisfactory tests were made on polythene, which gave a strength of about 6.5×106V/cm at room temperature to −190° C, and on polyvinyl chloride-acetate, the strength of which increased from about 6.5×106V/cm at room temperature to 12×106V/cm at −190° C. The polythene was crystalline and the results correspond to those for inorganic crystalline materials, and with the theory for such crystals. The copolymer was amorphous, its behaviour is similar to that of varnishes, and may be explained by Fröhlich's most recent development of the theory for amorphous substances.

DOI:10.1049/ji-1.1946.0155

出版商:IEE    

年代:1946

数据来源: IET

摘要:

Mr. N. W. Lewis has shown† that if the values of three resistors are three consecutive terms of the geometric series in which each term is the sum of the three preceding terms, then the distribution of the 17 resistance values attainable by various combinations of the resistors is closely related to another geometric series with a common ratio not exceeding 6:5, covering approximately a decade in 16 steps.In this paper it is shown that as the number of resistors is increased the ratios between consecutive steps can be arranged to become increasingly more uniform without exceeding the same 6:5 ratio, but over an extended range. Alternatively, increased uniformity can also be obtained with more steps of lower consecutive ratio value.Tables are worked out for four and five resistors respectively. These are followed by a short summary of the results obtained and a brief analysis of the general properties of the λ-series (λ being the common ratio of the geometric series).

DOI:10.1049/ji-1.1946.0156

出版商:IEE    

年代:1946

数据来源: IET

DOI:10.1049/ji-1.1946.0157

出版商:IEE    

年代:1946

数据来源: IET

DOI:10.1049/ji-1.1946.0159

出版商:IEE    

年代:1946

数据来源: IET

DOI:10.1049/ji-1.1946.0160

出版商:IEE    

年代:1946

数据来源: IET

DOI:10.1049/ji-1.1946.0161

出版商:IEE    

年代:1946

数据来源: IET