Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 6, Issue 25, 10 December 1970
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Volume 6, Issue 25
10 December 1970
Dependence of admittance of plasma capacitor on electron collection
- Author(s): I.L. Freeston
- Source: Electronics Letters, Volume 6, Issue 25, p. 793 –794
- DOI: 10.1049/el:19700546
- Type: Article
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p.
793
–794
(2)
The measured conductance of an uninsulated pair of rings is significantly greater than that of an insulated pair at frequencies where resonant-probe effects occur, and where electroacoustic waves are radiated. It is shown that electron collection does not cause the nonlinear admittance investigated previously.
Ground-wave propagation at medium and low frequencies
- Author(s): S. Rotheram
- Source: Electronics Letters, Volume 6, Issue 25, p. 794 –795
- DOI: 10.1049/el:19700547
- Type: Article
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p.
794
–795
(2)
General methods of computing tropospheric diffraction fields in atmospheres whose modified refractive index increases monotonically with height are indicated, new ground-wave-propagation curves are predicted, and the effective-Earth-radius transition at medium and low frequencies is given.
Eigenvalue assignment in multivariable systems incorporating integral feedback
- Author(s): H.M. Power and B. Porter
- Source: Electronics Letters, Volume 6, Issue 25, p. 795 –796
- DOI: 10.1049/el:19700548
- Type: Article
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p.
795
–796
(2)
An algorithm is derived for calculating a feedback law to assign a desired spectrum of eigenvalues to a multivariable system incorporating feedback of the integrals of r state variables, where 1 ≤ r ≤ n, where n is the dimension of the system without integral action.
Radiation pattern of imperfect paraboloidal reflectors
- Author(s): R.H. Slater
- Source: Electronics Letters, Volume 6, Issue 25, p. 796 –798
- DOI: 10.1049/el:19700549
- Type: Article
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p.
796
–798
(3)
The program transforms the numerically expressed phase variations in a plane electromagnetic wave over a circular aperture into the radiation pattern at infinity for directions in the region of that normal to the aperture plane. The program is of use in evaluating the radiation pattern of paraboloidal radio reflectors which have some known imperfections in their surface.
Parallel counting of binary patterns
- Author(s): S. Levialdi
- Source: Electronics Letters, Volume 6, Issue 25, p. 798 –800
- DOI: 10.1049/el:19700550
- Type: Article
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p.
798
–800
(3)
A shrinking algorithm that works in parallel has been implemented on an 8×8 matrix on which binary patterns are digitised. This shrinking technique has been used for normalising and counting patterns preventing merging when some objects containing others are present.
Extension of the inverse Nyquist method
- Author(s): P.D. McMorran
- Source: Electronics Letters, Volume 6, Issue 25, p. 800 –801
- DOI: 10.1049/el:19700551
- Type: Article
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p.
800
–801
(2)
Rosenbrock's stability theorem for linear multivariable control systems is extended to include unstable plants and systems with dynamics in the feedback path.
Universal sequential logic elements
- Author(s): I. Aleksander and E.H. Mamdani
- Source: Electronics Letters, Volume 6, Issue 25, p. 801 –802
- DOI: 10.1049/el:19700552
- Type: Article
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p.
801
–802
(2)
Feedback is applied to combinationally universal elements and the universal nature of the resulting sequential circuits is examined. For a certain balance of internal states to input symbols, the system may be made to behave as any sequential machine of such states. Also, the variable-structure nature of autonomous versions of the scheme may be used in list-processing storage.
Generalisation of a method for system identification using almost periodic functions
- Author(s): R.J. Simpson and H.M. Power
- Source: Electronics Letters, Volume 6, Issue 25, p. 803 –804
- DOI: 10.1049/el:19700553
- Type: Article
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p.
803
–804
(2)
A general method is described for calculating the parameters of a 4-level aperiodic input used in a scheme proposed recently for identification of the linear portions of a system containing a zero-memory nonlinearity.
Optimisation of electro-optic crystal modulators
- Author(s): D. Kalymnios
- Source: Electronics Letters, Volume 6, Issue 25, p. 804 –805
- DOI: 10.1049/el:19700554
- Type: Article
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p.
804
–805
(2)
A general method is given for the optimum design of electro-optic light modulators in respect of minimum halfwave voltage for crystals of any class. Examples are given for materials of class 42m (XDP).
Theorem on nonoptimal controls
- Author(s): L. Lupaş
- Source: Electronics Letters, Volume 6, Issue 25, page: 806 –806
- DOI: 10.1049/el:19700555
- Type: Article
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p.
806
(1)
It is indicated that it is possible to give an evaluation of performances for nonoptimal controls derived from a restricted class of optimal problems.
Computer analysis of the fundamental and higher-order modes in single and coupled microstrip
- Author(s): J.B. Davies and D.G. Corr
- Source: Electronics Letters, Volume 6, Issue 25, p. 806 –808
- DOI: 10.1049/el:19700556
- Type: Article
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p.
806
–808
(3)
By means of finite-difference methods, dispersion curves are obtained for the fundamental and higher-order hybrid modes in both single and coupled microstrip. Structures of realistic proportions are investigated by the use of a graded finite-difference mesh. Variational methods are used in deriving the finite-difference equations.
Mode-controllability matrices of multivariable linear systems incorporating integral feedback
- Author(s): B. Porter and H.M. Power
- Source: Electronics Letters, Volume 6, Issue 25, p. 809 –810
- DOI: 10.1049/el:19700557
- Type: Article
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p.
809
–810
(2)
Explicit expressions are derived for the mode-controllability matrices of linear systems incorporating integral feedback. These expressions greatly facilitate design, since they exhibit very clearly the mode-controllability characteristics of such systems; in addition, simple analysis of these expressions confirms the results concerning the controllability of systems of this class previously obtained by Porter and Power using the properties of system-controllability matrices.
Ion current to a plane probe in a flowing plasma
- Author(s): I.L. Freeston and J.E. Kelk
- Source: Electronics Letters, Volume 6, Issue 25, p. 810 –811
- DOI: 10.1049/el:19700558
- Type: Article
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p.
810
–811
(2)
An expression is developed for the ion current to a plane probe in a flowing plasma, for the probe surface parallel to the ion flow, and neglecting ion thermal motion. The application of the result to the measurement of plasma density of a plasma torch is considered.
Measurement of ion density in a plasma torch using a plane probe
- Author(s): I.L. Freeston and J.E. Kelk
- Source: Electronics Letters, Volume 6, Issue 25, p. 812 –813
- DOI: 10.1049/el:19700559
- Type: Article
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p.
812
–813
(2)
The plasma density of the flame of a plasma torch has been determined from the current to a plane probe using two theories. One includes only the ion flow motion; the other includes only the ion thermal motion. Comparison with spectroscopic results suggests that both motions should be included.
Polarisable dielectrics for m.o.s.t.s
- Author(s): J.H. Alexander ; R.C. Chittick ; C.F. Drake ; I.F. Scanlan
- Source: Electronics Letters, Volume 6, Issue 25, p. 813 –814
- DOI: 10.1049/el:19700560
- Type: Article
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p.
813
–814
(2)
The use of a new and polarisable dielectric layer has made it possible to obtain large threshold-voltage shifts in m.o.s. capacitors.
Rational approximants to the matrix exponential
- Author(s): V. Zakian
- Source: Electronics Letters, Volume 6, Issue 25, p. 814 –815
- DOI: 10.1049/el:19700561
- Type: Article
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p.
814
–815
(2)
The letter develops a method for obtaining a square matrix eNAt such that every element of eNAt is a proper rational function of t and is an efficient approximant to the corresponding element of the matrix exponential exp (At). Some useful general properties of eNAt are deduced and various procedures for computing eNAt are discussed.
Necessary and sufficient conditions for controllability of multivariable systems incorporating integral feedback
- Author(s): H.M. Power and B. Porter
- Source: Electronics Letters, Volume 6, Issue 25, p. 815 –816
- DOI: 10.1049/el:19700562
- Type: Article
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p.
815
–816
(2)
Necessary and sufficient conditions are derived for controllability of linear multivariable time-invariant systems incorporating feedback of the integrals of some or all of the state variables. The results extend recent work by Porter and Power on establishing necessary conditions for controllability of such systems.
Relationship of the Poisson transform to the moment functional transformation
- Author(s): F.W. Fairman
- Source: Electronics Letters, Volume 6, Issue 25, p. 816 –817
- DOI: 10.1049/el:19700563
- Type: Article
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p.
816
–817
(2)
A practical online method is developed for the generation of Poisson transforms for signals with finite support.
Resistivity calculations for inhomogeneously doped germanium
- Author(s): M.L. Gupta and A.B. Bhattacharyya
- Source: Electronics Letters, Volume 6, Issue 25, p. 817 –818
- DOI: 10.1049/el:19700564
- Type: Article
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p.
817
–818
(2)
An analytical expression defining the total mobility μ in germanium as a function of doping and temperature is obtained. Although based on certain empirical relations, the expression for μ is found to be reasonably valid in the useful and normally encountered concentration and temperature ranges. The mobility thus obtained is used to calculate the average conductivity of diffused impurity layers (p type) in germanium for Gaussian and complementary-error-function distributions. Results thus obtained are found to be in good agreement with those obtained by the numerical integration method.
Comments on ‘Equivalent linear and nonlinear discrete-time systems’
- Author(s): B.V. Dasarathy
- Source: Electronics Letters, Volume 6, Issue 25, p. 818 –819
- DOI: 10.1049/el:19700565
- Type: Article
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p.
818
–819
(2)
Results previously derived for 1st-order discrete-time systems are extended to higher-order systems.
Behaviour of a low-noise microwave f.e.t. at low temperature
- Author(s): B. Loriou ; M. Bellec ; M. Le Rouzic
- Source: Electronics Letters, Volume 6, Issue 25, p. 819 –820
- DOI: 10.1049/el:19700566
- Type: Article
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p.
819
–820
(2)
The values of gain and noise figure at 1000 MHz were measured against temperature (from 300 to 77K) for a GaAs f.e.t., in common-source configuration. An important decrease in noise figure from 3.2 to 1.5 dB with a 2 dB increase in gain was observed.
Electrical behaviour of networks synchronously switched by thyristors
- Author(s): J.H. Wouterse
- Source: Electronics Letters, Volume 6, Issue 25, p. 820 –823
- DOI: 10.1049/el:19700567
- Type: Article
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p.
820
–823
(4)
As a continuation of an aspect of the investigations by Van Wyk on synchronously switched stator-controlled machines, the letter describes a numerical solution to the general problem of finding the induced voltage part of the total excitation voltage, i.e. the machine voltage during the nonconducting period of the switch.
General renormalisation transforms for 3-port S parameters
- Author(s): D. Woods
- Source: Electronics Letters, Volume 6, Issue 25, p. 823 –825
- DOI: 10.1049/el:19700568
- Type: Article
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p.
823
–825
(3)
In the measurement of 3-port S parameters in terms of conventional incident and reflected voltage waves, the characteristic impedances of the three measurement ports may not be ideal, owing to discontinuities and other circuit limitations. It is therefore necessary to renormalise the measured values to the ideal characteristic impedances. These procedures are relatively simple to perform when an online computer is employed. The transforms given are general, in that the six impedances involved are all different.
Leakage currents, surface current and 1/f noise in planar bipolar transistors
- Author(s): K.F. Knott
- Source: Electronics Letters, Volume 6, Issue 25, p. 825 –826
- DOI: 10.1049/el:19700569
- Type: Article
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p.
825
–826
(2)
Using arguments based on the d.c. equivalent circuit of a planar bipolar transistor, it is shown that the ratio ICEO/ICBO is a measure of the significance of surface recombination current. Measurements of 1/f noise and ICEO/ICBO for a variety of transistors provide new evidence that the 1/f noise is due to the surface recombination current.
Learning in potential-function classifier
- Author(s): B.G. Batchelor ; N.L. Ford ; B.R. Wilkins
- Source: Electronics Letters, Volume 6, Issue 25, p. 826 –828
- DOI: 10.1049/el:19700570
- Type: Article
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p.
826
–828
(3)
An earlier letter showed that the potential-function classifier is a member of a general family of classifiers. The letter describes experiments intended to test the usefulness of the family relationship by applying to the potential-function-classifier training methods originally developed for a different classifier. These methods proved successful.
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