摘要:

A finite-element method for calculating power frequency 3-dimensional electromagnetic field distributions is described. The problem region is partitioned into regions which contain no eddy currents, and regions in which eddy currents flow in such a way that the dividing surfaces are the surfaces of the conductors. Magnetic scalar potentials are then used to describe the field in non-eddy regions. A magnetic vector potentialAis used in eddy regions. If the conductor permeability is nonuniform Lagrangian multipliers are also needed to enforce the zero divergence ofA.

DOI:10.1049/ip-a-1.1983.0043

出版商:IEE    

年代:1983

数据来源: IET

摘要:

Design curves for direct temperature estimation of adiabatic heated high-resistance conductors are accurately integrated. Specific destruction energy of constantan, manganin and nichrome wires are measured. A table of relevant design data is presented.

DOI:10.1049/ip-a-1.1983.0044

出版商:IEE    

年代:1983

数据来源: IET

摘要:

A new mehod is described for calculating the field produced by a rectangular array of large charged cylinders. The method involves finding an arrangement of sources (line charges) which satisfy, with acceptable accuracy, the boundary conditions in the unit cell surrounding the cylinder. Two cases are described: an array in which alternate rows of cylinders are charged positively and negatively and an array in which alternate cylinders in each axial direction are oppositely charged. Computer plots of fields calculated for typical arrangements of line charges are given, which are used to determine the relationships between proportions of the unit cell, the values and positions of charges, the cylinder radius, and for estimation of accuracy of the simulation. It is shown that accuracy is acceptably high for the different proportions of unit cells and cylinder radii studied.

DOI:10.1049/ip-a-1.1983.0045

出版商:IEE    

年代:1983

数据来源: IET

摘要:

Many procedures have been described for calibrating a 6-port reflectometer. Some of these require externally switched components such as phase shifters or attenuators. These complications are avoided in the 5-standard calibration technique described, which needs only two airlines in association with short circuits and open circuits. The use of a matched load standard is also avoided, because those commercially available are not good enough for that purpose. The new technique is considered to be a significant improvement on the previously published method requiring seven standards, comprising five modulus-1 standards and two others having a modulus considerably less than unity.

DOI:10.1049/ip-a-1.1983.0046

出版商:IEE    

年代:1983

数据来源: IET

摘要:

The conductivity of the surface layers of a metal is measured industrially by eddy-current conductivity meters which need to be calibrated. The method described here allows the resistivity of an annular specimen, as measured by the eddy-current losses at frequencies in the range 10–100 kHz, to be measured in units traceable to national standards. The apparatus is based on a Heydweiller bridge which measures the mutual inductance and mutual resistance of two toroidal windings on the annular specimen. Corrections are needed for the effects of self capacitance and the capacitance between windings. The overall uncertainty in the measurement is from about 0.4% at 10 kHz to 0.6% at 100 kHz, and it could not easily be improved. This is adequate for present purposes.

DOI:10.1049/ip-a-1.1983.0047

出版商:IEE    

年代:1983

数据来源: IET

摘要:

The problem of a metallic toroid immersed in a homogeneous electric field is treated in the paper. The expression for the potential in the space around the toroid is given. Electric field strengths at the surface and axis of the toroid are described in terms of normalised functions. The influence of toroid dimensions on the electric field distribution is also shown.

DOI:10.1049/ip-a-1.1983.0048

出版商:IEE    

年代:1983

数据来源: IET

摘要:

The propagation equations with transient parameters are the only time-domain equations able to represent, without approximations, the skin effect in the line and in the earth. These equations were completed with a nonlinear term taking into account a simplified model of the impulsive corona effect, based on previous laboratory studies. A computer program for numerical integration of the new equations, for a unifilar line with earth return, was developed, and some applications were carried out, for various wave shapes and earth conductivities, involving lightning overvoltage propagation. The calculated results from tests on a high-voltage transmission line are in good agreement with the measured values. This shows that the attenuation, as well as the distortion, of the propagated lightning waveshape can be predicted by means of calculation for a unifilar line with earth return.

DOI:10.1049/ip-a-1.1983.0049

出版商:IEE    

年代:1983

数据来源: IET

摘要:

In recent years, the concept of networking has emerged in both the physical and social sense. In particular, the rapid growth of microprocessing has enabled many communication networks to develop; from the global teleconferencing networks to the interdepartmental type of system for microcomputers. Similarly, social networks in the form of nonhierarchical but dedicated groups of people have multiplied enormously during the past decade. The collective drive of individuals now influences the way we are governed at both international and local levels. The paper examines the general characteristics of networks and the factors which influence their stability. Particular attention is given to the idea of ‘coupling strength’ and ‘connectivity’ between elements of a network. Examples drawn from social networks in management and politics indicate some of the possibilities for social analysis given the rapid rise in microcomputing power now available to all.

DOI:10.1049/ip-a-1.1983.0050

出版商:IEE    

年代:1983

数据来源: IET

摘要:

It is the author's view that, on a long term basis, a stable world free from major war is only possible if the developed countries reduce their energy consumption to about the present world average per-capita figure, i.e. about 2 tons of coal equivalent per capita per annum (2 TCE/c.a), and help the underdeveloped countries to achieve self sufficiency in energy and food at a comparable level. Both from this point of view and because of the cost of energy to the consumer in the rich countries, the author believes that the only feasible long-term policy for a developed country such as Britain is as follows:(i)There should be investment in energy conservation by investing capital and by other methods (such as the elimination of built-in obsolescence) as if fossil fuels cost several times as much as they do.(ii)Electricity is too precious a fuel to waste on the low-grade purposes of space and water heating, and so we should not build any new power stations but convert old ones in cities to coal firing with pass-out heat systems for houses and industry. This would give fruitful employment to the construction and heavy-engineering industries for many years.(iii)Solid fuels (preferably smokeless) should be available for all space and water heating whenever pass-out heat from power stations cannot be made available. Research on manless coal mining should be carried out very actively.(iv)A substantial amount of Government money (e.g. 20% of that spent on defence) should be devoted to ‘intermediate’ or ‘alternative’ technology, especially on the provision of village renewable energy systems.

DOI:10.1049/ip-a-1.1983.0051

出版商:IEE    

年代:1983

数据来源: IET

摘要:

The author of the paper, presented at a Savoy Place meeting of the Management and Design Division, received and presented on the 25th January 1983 at a joint divisional lecture with the Computing and Control Division, makes a detailed and discerning analysis of the factors implicit in ‘management style’, with particular reference to his own experience in an international group of technological companies. Some 50 subsidiaries are each headed by a local national. The group applies world-wide ethical standards, and expects each manager at all levels to understand both his own culture in depth, and also the culture he may be moving into when joining a foreign affilicate. Rather than try to impose the management style of the parent company on foreign affiliates, it is far better to attempt to draw the greatest benefits from the unique style of each culture: some European examples of this are quoted.

DOI:10.1049/ip-a-1.1983.0052

出版商:IEE    

年代:1983

数据来源: IET