摘要:

A linearised hydrodynamic theory is used to deduce expressions for the electromagnetic and plasma components of far fields, and of the radiation resistance, of a square-loop or Alford aerial immersed in an isotropic warm plasma, assuming a general value for the propagation coefficient of the current distribution. The radiation resistances predicted by this theory are compared with measurements of radiation resistance obtained in theAriel 3-satellite experiment. It is concluded that the propagation coefficient for the current distribution on the aerial in the plasma should be close to that of electromagnetic waves propagating in the plasma.

DOI:10.1049/piee.1971.0113

出版商:IEE    

年代:1971

数据来源: IET

摘要:

The region-adjacency matrix of a planar graphGis the vertex-adjacency matrix of its geometric dualG'. Thus, regional connectivity inGhas precisely the properties of vertex connectivity inG'. This duality is used to advantage in a routine presented in the paper for enumerating all the circuits inGfrom the set of vertex cutsets inG'. The routine yields each circuit uniquely, and circumvents a certain combinatorial tedium which is present in circuit-enumeration techniques proposed previously by Raoet al.and Maxwell and Reed.

DOI:10.1049/piee.1971.0114

出版商:IEE    

年代:1971

数据来源: IET

摘要:

The paper is concerned with the problem of determining, by terminal experiments, whether a given combinational switching circuit operates correctly or whether it is impaired by some malfunction. We shall be primarily concerned with permanent faults due to component failures. It is assumed that other procedures will be employed to protect the circuit against the effects of transient faults. A method is presented for the detection of failures in combinational switching circuits. The method provides minimal sets of tests for 2-level circuits and nearly minimal sets of tests for multilevel circuits.

DOI:10.1049/piee.1971.0115

出版商:IEE    

年代:1971

数据来源: IET

摘要:

The role of optimisation in the field of circuit design is fully discussed, using some actual designs to illustrate the principles involved. A review of the more important optimisation methods is presented, and comparative tests have been carried out on realistic circuit designs. The design of these circuits would have proved difficult, if not impossible, by conventional methods. Both least-square and minimax-error criteria are discussed, and methods for dealing with constraints are considered. Attention is drawn to the partial-noise-immunity property of the simplex algorithm and its use as the basis of an experimental procedure.

DOI:10.1049/piee.1971.0116

出版商:IEE    

年代:1971

数据来源: IET

摘要:

A user-oriented computer program based on the iterative piecewise-linear method is described, which offers a more general approach for analysing multivalued networks than the more commonly used Newton-Raphson method.

DOI:10.1049/piee.1971.0117

出版商:IEE    

年代:1971

数据来源: IET

摘要:

The paper describes the use and design of 4-wire trunk concentrators to save 4-wire facilities between two points, and gives an example of their use. The relative merits of electronic and electromechanical designs are discussed.

DOI:10.1049/piee.1971.0118

出版商:IEE    

年代:1971

数据来源: IET

摘要:

The field distribution in reluctance machines with profiled segmented rotors is analysed using numerical and analytical conformal-transformation techniques. Results, necessary for the sound design of such machines, are presented in terms of the permeance factors applicable to the regions of the field between segments and the fringe factors applicable to the fluxes passing to the stator.

DOI:10.1049/piee.1971.0119

出版商:IEE    

年代:1971

数据来源: IET

摘要:

Multispeed p.a.m. windings are now well established in electrical engineering practice, particularly for close pole ratios, such as 4/6 poles, 6/8 poles etc. Manufacture of these windings is simple, though the theory is very difficult. One of the key techniques for generalising this theory is a ‘clock diagram’ of a novel type. The paper therefore gives a short analysis and explanation of the clock diagram for p.a.m. windings, as a guide to a more general understanding of the principles involved.

DOI:10.1049/piee.1971.0120

出版商:IEE    

年代:1971

数据来源: IET

摘要:

Circulating currents are produced within stator windings of Roebel bars by endregion leakage fields, causing voltages to arise between the strands or subconductors. A method for calculating the endregion fields arising from both rotor and stator is given, and values of voltage for a simplified bar representation are obtained. The impedance of a Roebel bar to a circulating current is discussed, and values of circulating current are obtained for one machine. It is shown that the circulating currents in each bar are substantially independent of those in other bars, but that the reactance within each bar is of the same order as the resistance. The circulating-current loss is a small component of the total loss in the machine considered (10% of the statorI2Rloss), but varies with the load and the power factor. Its significance is that two-thirds of it occurs in the top layer of the stator winding, increasing the temperature rise there by 13%. The theoretical analysis from which the above conclusions are drawn is confirmed by search-coil measuremnets which show an average agreement within 18%.

DOI:10.1049/piee.1971.0124

出版商:IEE    

年代:1971

数据来源: IET

摘要:

The design and principle of operation of a sample-and-delay circuit are described in the paper. The voltage controlled phase-delay circuit has a wide dynamic range of usable linearity. It has been successfully applied to a convertor model as a phase-delay controller for the control of constant current. An approximate method is given for the estimation of the dynamic behaviour of the closed-loop system. It is also shown that the same controller can be used in a new constant-extinction-angle control system, which has the possibility of reduced susceptibility to disturbances in the commutation voltage.

DOI:10.1049/piee.1971.0126

出版商:IEE    

年代:1971

数据来源: IET