摘要:

The author shows that considerable developments are taking place in the use of electricity in railway signalling. Economic conditions have been responsible for the closing of many signal cabins and the substitution of electrical devices.The use of code transmission has been introduced into a number of systems for the control of signals and points, cab signals, track circuits, and train description. The mechanically interlocked lever frame is giving place to electrical interlocking, and in some cases thumb-switch control is being used. Results obtained from an economic and a reliability point of view are surveyed.In conclusion the author draws attention to the further need for track circuits and automatic train control. The symbols used are those published by the British Standards Institution—B.S.S. 376, Parts 1 and 2—wherever they can be made to apply.

DOI:10.1049/jiee-1.1936.0057

出版商:IEE    

年代:1936

数据来源: IET

摘要:

The paper describes the principal developments in inductionmotor construction which have taken place during the past few years.A full description is given of a number of welded-steel yokes or stator frames made by different manufacturers together with a discussion of the advantages and disadvantages of this type of frame.The welded-steel rotor centre or spider is similarly described in detail and discussed.The general trend of mechanical construction is outlined, together with considerations affecting enclosure and ventilation, while the construction of end-shields, pedestal-onbracket machines, and bedplates, is discussed.The magnetic forces between stator and rotor are explained and an improved expression for the calculation of unbalanced magnetic pull is developed, and extended by means of examples to show the characteristics of this type of loading.The sources of the various types of noise in an induction motor are classified and discussed.

DOI:10.1049/jiee-1.1936.0062

出版商:IEE    

年代:1936

数据来源: IET

摘要:

This paper describes the results of experience in the design of studios for the British Broadcasting Corporation. A brief historical account is given of some of the difficulties encountered prior to the commencement of a new series of acoustical measurements in 1929.The fundamental bases for experiment are then discussed, and a description is given of the reverberation room and equipment for the determination of the sound-absorbing characteristics of materials available for acoustical treatment. As a result of these measurements, building-board was adopted as a material for general use in studio treatment. Experience with Broadcasting House studios showed the importance of structural resonance as a factor in studio design. A general discussion of the effect of resonance upon studio acoustics is given.The acoustics of various studios actually constructed are discussed in the light of the general principles laid down, the effect of details of construction being considered in particular.The paper concludes with a brief consideration of the effect of irregular shapes and surfaces in studio acoustics, and gives preliminary results of experiments made to investigate this question directly.

DOI:10.1049/jiee-1.1936.0066

出版商:IEE    

年代:1936

数据来源: IET

DOI:10.1049/jiee-1.1936.0073

出版商:IEE    

年代:1936

数据来源: IET

摘要:

An investigation has been made of the generation of continuous-wave oscillations by a split-anode magnetron (excluding the ultra-short waves).It has been found that there are two types of oscillation: the first in which the strongest oscillations over a large range of wavelengths are produced by the same set of values of the voltage and field applied, and the second in which each wavelength has a particular set of values of voltage and field for best results, but these sets are different for every wavelength. A simple relation has been found experimentally between the wavelength, field, and voltage, in this latter case. A theory has been developed (not yet complete mathematically) to show that the first results are due to a pure negative-resistance effect, and the latter to a type of amplified negative resistance which involves a resonance.The theory is confirmed by experiments with a valve having four segments in place of two, and with a valve of larger dimensions.

DOI:10.1049/jiee-1.1936.0074

出版商:IEE    

年代:1936

数据来源: IET

摘要:

The object of these experiments is to extend certain investigations by Faraday which have been the subject of much controversy. They concern the relations between a cylindrical magnet spinning about its axis and the currents and forces set up thereby in a neighbouring conducting circuit, of which the magnet may or may not form a part. The similarity between cylindrical magnets and solenoids is examined, as well as the effect produced by one spinning magnet upon another. The bearing of these experiments upon the laws of electromagnetic induction is explained, and certain special experiments on this subject are included. The conclusions reached are given in Section (15); and in an Appendix some practical applications are described.

DOI:10.1049/jiee-1.1936.0079

出版商:IEE    

年代:1936

数据来源: IET

DOI:10.1049/jiee-1.1936.0080

出版商:IEE    

年代:1936

数据来源: IET