摘要:

The integrated circuits produced on a manufacturer's process line incorporate a standardised m.o.s. transistor providing a set of seven process-parameter values per die at the wafer-probe stage. A statistical analysis of the parameters measured on batches of wafers withdrawn in consecutive weeks from the line shows that the batches received different process treatments. A similar analytical procedure applied to the individual wafers of the batches yields the more surprising result that the wafers were also dissimilarly processed.

DOI:10.1049/piee.1977.0099

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A trick permits the use of several aliased fast Fourier transforms (f.f.t.) in place of a single unambiguous f.f.t. If the proportion of active spectral lines, or directions of arrival, is well under 1%, their location, but not the amplitude, can then be computed with a dramatically reduced workload.

DOI:10.1049/piee.1977.0100

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The asymptotic form of orthonormal eigenfunctions in the curved guide is obtained, and an integral equation is set up for the junction field. The latter is found as a power series in theguide curvature, and the first-order coefficient is determined explicitly. The odd-order mode-conversion coefficients are found to the first order and vary asymptotically as the inverse cubeof the mode order. A variational technique then determines the reflection coefficient exactly, to the second order in the curvature expansion parameter. The junction parameters are found to this order of accuracy, and are shown to involve a junction transformer which represents the radiation coupling between the dominant modes in the straight and curved guide sections. The even-order mode-conversion coefficients are found by a formulation analgous to that used for the reflection coefficient, and are shown to vary as the square of the curvature and asymptotically asthe inverse cube of the mode number. The form of the junction field is determined and is shown to possess a logarithmic singularity in its second derivative at the guide wall.

DOI:10.1049/piee.1977.0101

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The paper describes a technique for the computer-aided design of optical devices which are structured from multilayer thin films. The method overcomes some of the disadvantages usually associated with the design of optical multilayer systems, such as a requirement for approximate initial designs and excessive computing time. Results are presented for both bandpass and bandstop optical filters. The design system has been planned to integrate with the requirements of a computer-controlled process for manufacturing optical devices.

DOI:10.1049/piee.1977.0102

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The paper describes the design of a wideband antenna suitable for relay stations broadcasting in band II over the range 88–100MHz. The optimisation of various design parameters was carried out with a computer program to meet the desired performance standards. Subsequent measurements on a scale model confirmed the calculations. The antenna has an operating bandwidth from 88 to 100 MHz: An outline of the method of computation is appended.

DOI:10.1049/piee.1977.0103

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The performance characteristics of a junction field-effect transistor (j.f.e.t.) are evaluated considering the presence of the gap between the gate electrode and the source and drain terminals. It is concluded that the effect of the gap is to demand a higher drain voltage to maintain the same drain current. So long as the device is operated at the same drain current, the presence of the gap does not change the performance of the device as an amplifier. The nature of the performance of the device as a variable resistor is not affected by the gap if it is less than or equal to the physical height of the channel. For gap lengths larger than the channel height, the effect of the gap is to add a series resistance in the drain.

DOI:10.1049/piee.1977.0105

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The paper describes how positive and negative dependence between the nodal powers of a power system can be formulated and included in the probabilistic a.c. load-flow problem. A typical system is analysed using nodal powers that are assumed, first, to be totally independent, and, secondly, to exhibit dependence. This analysis indicates clearly that it is not possible to predetermine the effect of dependence and illustrates how the standard deviations and the shape of the probability-density curves of the calculated parameters change when dependence between the input nodal powers is assumed.

DOI:10.1049/piee.1977.0108

出版商:IEE    

年代:1977

数据来源: IET

摘要:

This paper considerably extends the modelling and evaluation techniques presently used in assessing the reliability of transmission and distribution networks. The concepts described lead to a realistic analysis of such systems. The most important features that are described concern the incorporation of all realistic failure and restoration modes, development of the concept for overall system indices, inclusion of variable repair times and the ability to extend the usual loss of continuity criterion to include loss of quality, this often being of vital importance. All the techniques and concepts discussed were used to analyse a typical system, the results of which are included in the paper.

DOI:10.1049/piee.1977.0109

出版商:IEE    

年代:1977

数据来源: IET

摘要:

Design data are presented in the form of permeance factors for the airgap between doubly-slotted surfaces, for the cases in which the teeth are perfectly aligned and symmetrically misaligned. Data previously available are thus extended to become applicable to stepping motors as well as to other types of machine, and the new data are in a more convenient form. The permeance factors are used to calculate the average force over a step length, and these results confirm the accuracy of earlier studies based on more approximate data. The effect of finite slot depth is discussed, and the solution of the troublesome implicit equations involved is obtained using a patternsearch minimisation procedure.

DOI:10.1049/piee.1977.0110

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A method of analysing sequential short circuits on a synchronous machine is presented, and is applied to the detailed analytical solution for the armature currents following a line-to-line/3-line and a line-to-neutral/3-line-toneutral short circuit. The analysis is carried out in thed,q,oreference frame by a Laplace transform method using the voltages during the unbalanced s.c., which are known from previous analyses. The results show that, following the 3-phase s.c., the currents decay with the same time constants as during a simultaneous 3-phase s.c. together with an additional time constant for the ‘o’ component in the s.c. involving the neutral. The magnitudes of all these components, not just the asymmetrical component as indicated by previous workers, are influenced by the duration and time constants of the unbalanced s.c. As pointed out by previous authors, it is shown that a sequential s.c. can be more severe than a simultaneous s.c., if the duration of the initial s.c. is short compared with the subtransient time constants. The effect of subtransient saliency, which is included in the analysis, is also discussed.

DOI:10.1049/piee.1977.0112

出版商:IEE    

年代:1977

数据来源: IET