摘要:

This paper describes an approach to the detection of turns in a radar tracking system and discusses some of the difficulties encountered in a multiradar system when using more conventional manoeuvre detectors withα-βor Kalman filter trackers. Typical aircraft tracks are presented to illustrate the improvements possible using the approach described.

DOI:10.1049/piee.1979.0113

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A 2-axis sum-and-difference monopulse radar incorporating a signal processor which is close to optimum is considered to operate in an environment consisting of a Rayleigh fluctuating target and an arbitrary spatial distribution of fluctuating sources of clutter and intereference or jamming. The bivariate probability density function for the system indications, one for each axis, is derived and some examples of monopulse operation are considered.

DOI:10.1049/piee.1979.0114

出版商:IEE    

年代:1979

数据来源: IET

摘要:

An f.s.k. signal keyed at 75 bauds with 850 Hz frequency shift, can have one of several frequency allocations within any given h.f. voice channel. In the presence of interference from other users, the f.s.k. system performance may be improved by choosing the f.s.k. tone frequencies before message transmission, to correspond to frequencies within the voice channel where the interference is least. This paper reports on an 800 km point-to-point h.f. link experiment which investigated this principle, combined with forward error-correcting codes, with the aim of improving aeromobile data transmission.

DOI:10.1049/piee.1979.0115

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The input admittance of an elemental radiator on a curved surface, e.g. a slot on a cone, plays an important role in the design of conformal arrays. A search through the literature reveals that, at present, there is no reliable theoretical method available for computing this admittance. The objective of this paper is to provide a solution to this problem using a surface-ray approach–within the framework of g.t.d. The solution is verified for the limiting case where the cone degenerates into a cylinder, and it is shown that the g.t.d. results compare extremely well with the exact modal solution to the cylinder problem. Extensive numerical results are presented in the paper for the input admittance of a cone as a function of various design parameters.

DOI:10.1049/piee.1979.0116

出版商:IEE    

年代:1979

数据来源: IET

摘要:

With reference to the conventional quadrature booster transformer, this paper describes a way of achieving continuous phase-shift control based on point-on-wave thyristor switching. The proposed unit can provide continuous and practically instantaneous power-transfer control in transmission circuits. The theoretical waveforms are verified by experimental tests and computer studies. Consideration is also given to the harmonic content produced.

DOI:10.1049/piee.1979.0117

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The economy of u.h.v. lines is of such importance that it is essential to select the parameters which decide its cost in a most careful way. Therefore, the application of optimisation techniques to the design of a transmission line has been considered. A nonlinear algorithm, using the concept of n.l.p. algorithm, and a mathematical representation of the line have been developed.

DOI:10.1049/piee.1979.0118

出版商:IEE    

年代:1979

数据来源: IET

摘要:

In the present paper, the thermal and hydrological characteristics of the soil surrounding buried cables are investigated. First, the dependence of the soil thermal resistivity on two easily measurable parameters is shown. These parameters are the porosity and the saturation degree. The soil hydrological stability is then investigated and is found to be governed by one hydrological parameter only; namely, the saturation degree. Finally, the conditions governing soil hydrological equilibrium are investigated, which appear to be dependent both on the initial soil saturation degree and on the applied thermal gradient (i.e. on the thermal flow). In principle, on the basis of this simple information, it is possible to carry out a rational design of a buried-cables system preventing any hydrological instability.

DOI:10.1049/piee.1979.0119

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The summary discusses the computational aspects and requirements of load flow solution methods. In particular, new piecewise solution technique is considered. In the new algorithm, based on the Newton-Raphson method, the Jacobian is block diagonalised according to chosen subsystems, and the voltage correction vectors of the respective subsystems are solved independently. The effects of interconnections are taken into account using a method of successive approximation. The memory and computational requirements of the new technique are discussed and compared with those of the one-piece solution. The computational requirements are indicated analytically, facilitating examination of the effects of tearing. The number of subdivisions required to minimise computing effort is also indicated.

DOI:10.1049/piee.1979.0120

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The concept of anm×minvertible continuous first-order lag is extended to define an equivalent formulation for multivariable sampled-data systems. A large class of proportional-plus-summation-output feedback controllers is constructed. Each controller guarantees the stability of the closed-loop system and, also, low-closed-loop interaction effects if the sampling rate is high enough. The results are extended to show that a multivariable discrete first-order lag is, in many cases of practical interest, a quite adequate approximation for the purpose of controller design provided that the plant is minimum phase and satisfies a contraction-mapping condition. In particular, any discrete model of a minimum-phase continuous linear time-invariant plant with a nonsingular value ofCBwill satisfy the contraction condition provided that the sampling rate is high enough.

DOI:10.1049/piee.1979.0127

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The paper reports the results of an experimental investigation into the dielectric-breakdown behaviour of super-critical helium, in the range from 4.2 to 30 K and 0.4 to 1.5 MPa under d.c., a.c. and standard impulse voltages, to assist the development of superconducting power cables. At helium densities above 80 kg m−3, the uniform-field breakdown voltage for d.c. or a.c. is about 55 MV m−1at 0.8 MPa and has a slight pressure dependence. In nonuniform fields, the breakdown voltage with a negative electrode is considerably increased by corona stabilisation in the density range from 30 to 83 kg m−3.

DOI:10.1049/piee.1979.0128

出版商:IEE    

年代:1979

数据来源: IET