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A method of comparing the basic performance of electron guns is described. The method is applied to some recently computed results on two versions of an electron gun which has a hairpin-filament cathode.
In an interesting and useful paper by Worster (1979 a), hereafter referred to as JW, computed results are given relating to two electron guns. When the performance of the guns was compared it was concluded that one gun was better than the other in all respects. However, in making the comparison the electron beam divergence was not taken into account. Although the method of comparison used in JW may, of course, be satisfactory for some purposes, the computed results in JW are comprehensive enough to provide information for an alternative method of comparison which includes beam divergence. Such an alternative method, described in this note, leads to different conclusions. [ABSTRACT FROM AUTHOR]

Comments concerning on inconsistencies in the analysis of alpha-particle scattering. Validity of the field concept; Relation between the laws of physics and relativity; Information on the theory of electromagnetic.

Presents a reply on the inconsistency in the analysis of alpha-particle scattering. Correlation between electromagnetic field and vectors; Analysis of the geometry of vector functions; Distinction between motion and force.

To determine theoretically whether or not a positive column is stable requires a complete description of the energy balance, and hence precise knowledge of all excitation, ionization and other loss mechanisms. If such a description were available it would indicate either that the plasma is d.c. stable, i.e. perturbations tend to be damped, or that its equilibrium is one in which oscillations are present. In either case, it is to be expected that, the steady-state conditions obey the 'minimum energy' principle, as pointed out by Professor Hoyaux.
The purpose of our article was to show that both the experimental evidence, and the inferences to be drawn from knowledge of the relevant collision processes, indicate that the mercury-vapour positive column can be d.c. stable. The low-frequency oscillations commonly observed, and the more rarely observed high frequency ones, can be identified as originating in the cathode region. They propagate with damping along the column. By increasing the length of the column, the amplitude of these damped oscillations may be decreased indefinitely, far from the cathode.
It is certainly true in other gases, which exhibit standing or moving striations, that the uniform column is unstable against the perturbation corresponding to the striations, the stability being determined by the form of the relevant, collision cross-sections and we have no doubt that Steenbeck's principle would reveal, for such gases, that the striated . column has a lower average voltage drop than the uniform column. This is no reason, however, to attribute to plasma an evil genius for finding modes of instability. Plasmas are only as inventive as the laws of physics allow. Professor Hoyaux's 'guess' as to the ability of a mercury-vapour plasma always to succeed in finding an unstable mode of operation is no substitute for experiment and analysis. [ABSTRACT FROM AUTHOR]

Comments on the possibility of mercury vapor column existence on random process. Assessment on the stability of the column; Examination on the voltage drop of the oscillation; Effectivity of the Maxwellian distribution of electrons.

A simple potential divider circuit has been synthesized as a voltage stabilizer in this paper by establishing the relations between its mesh impedances and hence determining the nature of its individual coil elements by Kron's tensor method of synthesis.
The synthesis of various types of networks has been made by a number of workers, e.g. Tuttle (1958), Guillemin (1959), Kuo (1965), Valkenburg (1964), Weinberg (1962), Hazony (1971), Chirlian (1967), etc. by different classical methods. Kron (1939) first introduced tensors to the network synthesis. In Kron's method of synthesis certain desirable performance characteristics are given, the problem is to find the relations that must exist between the mesh impedances of the network in order to make the network perform as it is desired. These relations are called the ' criteria of performance ' by Kron. In this paper, the ' criterion of performance ' of a potential divider circuit (shown in fig. 1) acting as a voltage stabilizer has been established for a varying rectified voltage applied at the input, the output load being constant. From this criterion, the nature of the individual coil elements and hence the practical circuit arrangements may be derived readily. [ABSTRACT FROM AUTHOR]

This is the first of a series of three papers in which the basic physics of IMPATT diodes, their applications and limitations, and their prospects for the future will be discussed. This, the first instalment, concentrates on the underlying physical phenomena and the basic theory of the device. The fundamental semiconductor properties are reviewed, followed by a basic account of the avalanche and drift processes. This leads on to a description of the Read diode and an analysis of the device based on the sharp pulse approximation, where approximate large signal limits are derived.
The treatment of the device theory is then extended to give a realistic feel for the impact of various material parameters on device operation. The technique is to examine each material parameter as a perturbation on the sharp pulse approximation, and in this manner, the effects of the following parameters are examined: (1) The relationship between the r.f. voltage anti the electric riehl distribution throughout the cycle, including the effects of space charge during the transit time. (2) Deviations from the sharp pulse to a distributed injection--effectively accounting for finite avalanche zone width. (3) The effect of depletion layer width modulation on device operation to introduce a generalized form of the Ramo-Shockley theorem. (4) The effect of real velocity-field characteristics on the basic device characteristics.
A number of the associated issues are also covered including ' back bias ' and an elementary account of the impact of unequal ionization rates. This paper, which covers the phenomena pertinent to the avalanche diode, forms the foundation for the discussions of the actual device in the succeeding installments. [ABSTRACT FROM AUTHOR]

A new open circuit step cavity resonator for continuous and contactless monitoring of sheet moisture content is proposed. The return loss as well as the perturbation in the resonant frequency of the resonator due to variations in the moisture content of sample paper passing through the cavity are monitored in real time by terminal devices and interpreted to display the paper moisture content in digital or analog form. [ABSTRACT FROM AUTHOR]

In this paper we investigate the multi-stable transistor circuits of which basic operation can be regarded as threshold logic. The sensitivity analysis on the actual circuits is also considered as well as their logical behaviour.
The multi-stable circuits are usually constructed from the flip-flop circuits which have basically two transistors. The transistor, however, can be regarded as a comparator whose output ('0' or '1') depends on whether the input level is higher than a reference (including the insensitive region) or not. Hence, combining it with an adder circuit, each input of which is multiplied by some factor, the circuit operates as a threshold device (Hampel and Winder 1971).
In this paper we investigate these problems and suggest that the network constructed from n threshold devices is useful only as an n-stable circuit. [ABSTRACT FROM AUTHOR]

The paper is an extension of the authors' previous work on travelling-wave circular loop and helical antennas immersed in an isotropic compressible electron plasma. In the present paper the expressions for the electromagnetic and electroacoustic components of the radiation field and of radiation resistance in the case of an electrically large multi-turn circular loop antenna in plasma having a travelling-wave current distribution are derived. Finally, treating the multi-turn loop in vacuum as a particular case of the general results for the same in a plasma medium, expressions for electromagnetic field and radiation resistance have been obtained for different loop sizes and the number of turns in it. It is shown that its field and the radiation resistance, both in plasma and in vacuum, are seriously affected by the number of turns in the loop and under certain conditions much higher values of radiation resistance can be obtained. [ABSTRACT FROM AUTHOR]

To discuss the small amplitude disturbances propagating through a hot plasma in a uniform magnetic field, or to find the macroscopic quantities of a plasma, it is necessary to solve the Vlasov equation. In this paper a general vector method is presented and it will give a solution of the linearized Vlasov equation with a collision term. The explicit expressions of the perturbed distribution functions for both anisotropic and isotropic equilibrium distributions are derived. The results can be easily applied to find the dispersion equation and the polarization properties of the waves.
In recent years numerous studies have appeared in the literature concerning the high frequency properties of a plasma immersed in a static magnetic field. Such studies are significant in providing the basis for predicting the electromagnetic wave propagation and absorption in the ionosphere, and for explaining the origin of solar radiation, as well as the microwave diagnostic of plasma in thermonuclear reaction, etc. (Gross 1951, Sitenko and Stepanov 1957, Bernstein 1958). When the thermal velocities of the particles are negligible, or when the zero wavelength approximation is valid, the magneto-ionic theory gives a satisfactory treatment of waves in a plasma. However, if the effects of random thermal motions of the particles have to be considered, the kinetic theory will then become a necessity in our discussion. It not only offers a more complete and rigorous description of the plasma but also allows one to see which part the individual particle plays in sustaining the oscillation. The fundamental problem in the kinetic theory is to solve the Vlasov equation for a distribution function which can then be used to determine either the conductivity tensor and the dispersion equation or other macroscopic quantities of the plasma. Our objective in this paper is to present a vector method and to derive an explicit general solution of Vlasov equation. [ABSTRACT FROM AUTHOR]

Measurements on the wavelength and temperature dependences of the short-circuit current and open-circuit voltage of n-GaAs-p-AlGaAs (Ge-doped) heterojunctions under parallel illumination are reported. The results are explained using the theory of photoelectrical effects in ideal heterojunctions. Distinct contributions from each side of the heterojunctions were evidenced in the photoresponse spectra. The influence of heterojunction parameters on the photoelectrical response is discussed.
One of the fields in which the use of heterojunctions seems to be most promising is that of light conversion, in such devices as photodetectors or solar cells. The study of photoelectrical effects in heterojunctions is thus of increasing importance, from both applicative and fundamental points of view, as it also yields precious information concerning the properties of the materials which form the heterojunction.
Unfortunately, the performances of heterojunction devices are seriously limited by the existence of interface states, acting as traps or recombination centres. However, the pair GaAs-AlGaAs represents a fortunate exception, the two semiconductors having very close lattice constants, which made possible the preparation of almost ideal heterojunctions, i.e. with a small density of interface states, so that their effect is negligible (Alferov et al. 1968).
A first paper reporting some photoelectrical measurements on GaAs-AlGaAs heterojunctions is due to the group of J. I. Alferov (1969), who also published works on solar cells (Alferov et al. 1970) and selective heterophotoelements (Alferov et al. 1971) based on this heterojunction pair.
Recently Woodall and Hovel (1972) reported the realization of GaAs-AlGaAs solar cells with higher conversion efficiencies than the best silicon homojunction cells.
The purpose of the present paper is to make a more detailed study of the photoelectrical properties of... [ABSTRACT FROM AUTHOR]

Digital positioning systems often require a down counter for their operation. Due to the necessity of particular logic sequences and control of individual terminals, the design of down counters for particular use is very essential. In this paper the design procedure and logic diagram for a synchronous decade down counter with parallel carry are presented.
A counter is an important unit in any digital system. It has the ability to remember both the number and sequence of input pulses. The number of steps associated with any counter is decided by the number of bistable elements (e.g. flip-flops) used and also it can be changed by suitably combining the counter units themselves. Decade counters which have ten distinct states (modulo-'10') are the most popular in 'Numerical Control Work' (Ertell 1969) since decimal numbers can be directly interpreted. Such a counter can be constructed using essentially a higher modulus (modulo-'16') counter by skipping states. In this paper, a complete design procedure of a synchronous decade down counter with parallel carry is presented. [ABSTRACT FROM AUTHOR]

This paper presents an active RC synthesis of rational transfer functions using unity gain controlled sources. The denominator polynomial of the transfer function is decomposed in such a way that the pole sensitivity can be optimized to a prescribed value, the modulus and the argument of which can be easily controlled. The basic configuration can be used to realize the right-half (R.H.) s-plane transmission zeros. The present method is compared with those of Hakim and Cheung. The paper includes one design example. [ABSTRACT FROM AUTHOR]

The phenomenological theory of the electrodynamics of stationary material media was formulated by Maxwell. To allow a unique determination of the field vectors Maxwell's equations have to be supplemented by constitutive relations which describe the behaviors of the media under the influence of the field. The purpose of the present paper is to extend Minkowski's theory of a moving isotropic medium to include a gyro-electric magnetic medium. The properties of a transformation matrix are discussed first. Three sets of constitutive relations depending on the choice of independent field vectors for a moving gyro-electric magnetic medium are then derived explicitly. Maxwell's equations, together with the constitutive relations, thus form a complete theory of the electrodynamics of a moving gyro-electric -magnetic medium. With the properties of the transformation matrix stated in the paper, the results can be easily extended to an arbitrarily anisotropic medium. Some of the special cases previously treated by other authors are also considered. [ABSTRACT FROM AUTHOR]

In communication engineering the problem of synchronization is important and is usually achieved by use of a phase-locked loop. If for any reason synchronization is lost, then it is not only necessary that it be restored but it be done so in the shortest possible time. This paper considers precisely this problem. It is shown in Proposition 1 of the paper that the optimum non-linear device used in the feedback path of the phase-locked loop, which attains synchronization in the shortest possible time, is the 'on-off' device. In 3 approximation of this device by a continuous non-linear one is suggested and the corresponding results are presented both for fixed and variable input-phase angles. The conclusion of Proposition 1 is true under the assumption that the forward filter G is an ideal low-pass filter. In 4 steps are suggested for finding the optimal feedback device f* in case the filter G is not an ideal filter. [ABSTRACT FROM AUTHOR]

In this paper the design details of a wide band Sanky phase shifter have been given. This phase shifter can be used with phase-sensitive detectors which are required to work with variable reference frequencies. The phase shifter uses its own built-in oscillator that provides the reference frequency.
A phase-shifting network is essential in phase-sensitive detectors to compensate for the phase shifts occurring in an amplifier system. This network, which is normally used in the reference channel, often comprises R-C networks. The input and output of such networks are both sinusoidal. With such networks the 'control' cannot be calibrated, as the phase shift introduced for a certain amount of the 'control' movement is frequency dependent. Since, in switching-mode-operated phase-sensitive detectors, the reference is a train of square waves, a modified version of the Sanky phase shifter (Sankaranarayanan 1973) can be used to introduce necessary phase shifts and the 'control' can be straight away calibrated independent of frequency as described in this paper. Although, De Sa and Molynenx (1964) and Adby (1968) have suggested two different techniques for this purpose, the modified Sanky phase shifter becomes very handy and elegant to get the phase shifted. However, in this case, instead of using the normally available L-C or R-C type of oscillator to provide the sinusoidal wave train for excitation, an oscillator that gives a sinusoidal wave generated from a triangular wave has to be used. This is due to the fact that it is essential to have a constant amplitude triangular wave independent of frequency for phase shifting in the Sanky phase shifter. In this paper the design details of a wide band Sanky phase shifter have been given. This phase shifter can be used with phase-sensitive detectors which are required to work with variable reference frequencies. The phase shifter uses its own built-in oscillator that provides the reference frequency.
A... [ABSTRACT FROM AUTHOR]

The first part of the paper includes the derivation of a lump model for the basic CCD unit. This model consists of two capacitors, a current generator and a switch. Experimental results are given for the justification of this model.
In the second part of the paper a report is given on the successful operation of silicon gate CCD shift registers, two-phase and three-phase.
The last part presents photosensitivity results of CCD silicon gate shift registers operated as imaging arrays. The noise equivalent power (NEP) was 2 10 W/cm at a wavelength of 0.7 m. Relative output as a function of integration time is also given. [ABSTRACT FROM AUTHOR]

Many previous authorities have pointed out the potential advantages of threshold logic gates in comparison with Boolean gates in reducing the gate population per given system (Dertouzos 1965, Lewis 1967, Hurst 1972 a). All these previous comments on population reduction were made without considering the above additional factor of hazard-free realization.
This paper, however, shows that when hazard-free realizations are sought, a further advantage of using threshold gates accrues. The feature that the logic selection of a threshold gate is not a simple rectangle on a Karnaugh-map layout, but rather can be an irregular shape, is a very powerful tool for generating hazard-free networks. Thus an even greater potential saving in gate population per system is generated in this situation, in comparison with a hazard-free Boolean system. Many previous authorities have pointed out the potential advantages of threshold logic gates in comparison with Boolean gates in reducing the gate population per given system (Dertouzos 1965, Lewis 1967, Hurst 1972 a). All these previous comments on population reduction were made without considering the above additional factor of hazard-free realization.
This paper, however, shows that when hazard-free realizations are sought, a further advantage of using threshold gates accrues. The feature that the logic selection of a threshold gate is not a simple rectangle on a Karnaugh-map layout, but rather can be an irregular shape, is a very powerful tool for generating hazard-free networks. Thus an even greater potential saving in gate population per system is generated in this situation, in comparison with a hazard-free Boolean system. [ABSTRACT FROM AUTHOR]

This paper describes a hardware implementation of a two-way converter logic by which conversion between numbers from positive to negative binary representation is possible. Index terms : (i) Negative radix, (ii) Positive radix, (iii) Two-way conversion.
The present paper describes a hardware implementation of a slight modification of a scheme earlier presented by Krishnamurthy (1971). The interesting feature is that this converter can take an input (or give an output) in positive or 2's complement positive binary form as compared to the sign magnitude form by Zohar (1971). For carrying out two-way conversion, it is sufficient to switch a single level to a high or a low. [ABSTRACT FROM AUTHOR]

The paper deals with parametric phenomena in a non-linear oscillating circuit with negative resistance. The differential equations of the parametric excited circuit, for the case where the self-oscillations' amplitude is smaller than the amplitude of the pumping signal, reduce to the equations of Hill and are solved by an original method (Samoylo and Spasov 1970). In an investigations of the transient and steady-state regimes the real non-linearity of the reactive element in the oscillating circuit is considered. The mode of forced oscillations and the resonance of the second and third subharmonics of the pumping signal are discussed. The experimental results agree well with theory.
The results given in the paper may be of interest in an investigation of oscillating circuits, utilizing semiconductor elements with negative resistance : tunnel diodes, Gunn diodes, avalanche transit-time diodes, etc. [ABSTRACT FROM AUTHOR]

In a previous paper (Constantinescu et al. 1973), which shall in this paper be referred to as I, photovoltaic effects in p-n junctions under parallel illumination were discussed and mathematical expressions for the short-circuit current and open-circuit voltage were derived. One of the assumptions used there was, that all minority carriers generated outside the depletion region, which succeeded in reaching by diffusion the depletion (space-charge) region boundary, were swept away by the junction field and did not recombine in the 'thin' depletion layer, thus contributing to the photocurrent. However, as we shall see below, recombination of minority carriers after having reached the space-charge region, cannot always be neglected. For normally illuminated p-n heterojunctions this very situation was considered by Kagan and Liubashevskaia (1970), who found expressions for the short-circuit current in the presence of recombination in the space-charge region. In order to do the same for parallel illumination we shall again write the two-dimensional continuity equations, one for the neutral region and the other for the space-charge region of one side of the junction, for instance the n-type side (see I). Multiple line equation(s) cannot be represented in ASCII text (1) and Multiple line equation(s) cannot be represented in ASCII text (2) where p, D and T are the non-equilibrium (excess) minority carrier densities, diffusion coefficients and lifetimes, respectively, u, is the drift velocity of holes in the junction field, the absorption coefficient, the quantum efficiency and F the density of the incident photon flux. The symbols referring to the space-charge region are noted by an asterisk. [ABSTRACT FROM AUTHOR]

In a recent paper, Seth has pointed out the error in the derivation of the adjoint model of Director and Rohrer and has given the correct results which are applicable for time-domain analysis. This fact calls for a re-examination of the results obtained from considerations of inter-reciprocity between the sensitivity network and the adjoint network. The purpose of this paper is first to develop the sensitivity model in its most general parametric form and then establish a link with the corrected adjoint model through the use of the inter-reciprocity theorem. [ABSTRACT FROM AUTHOR]

Two different algorithms are presented to design lossless ladder filters. Both methods are developed from a characteristic equation of the filters. The first method defines a performance index J and, using the special properties of the formulation used, evaluates the gradient of J with respect to element values. Optimization routines are then used to obtain element values to give the desired response. The second method starts with the characteristic equation and obtains a set of algebraic equations to evaluate the errors in the element values. Using this information, element values are adjusted to obtain the desired filter.
In this paper different algorithms for computer-aided design of ladder filters are given. Two examples serve to illustrate the power of the method. The methods have proved to be practical and save a lot of engineering time which is needed to design general parameter filters using the curves and tables which have been supplied by Cauer and others. This paper also gives
an added importance to eqn. (15) which has not been used very often by filter designers. The methods are applicable for lossy filters as well. Modifications are needed only on eqns. (25) and (26). [ABSTRACT FROM AUTHOR]

A new static distance relay working on the principle of sequence detection is reported in the paper. The three-input sequence detector developed in the paper is simple and convenient to employ in obtaining the popular quadrilateral characteristic. The relay employs semi-conductor devices throughout and operates in less than a cycle.
The E.H.V., long, heavily loaded transmission lines are usually protected by means of distance relays. A static distance relay employing phase comparator may either work on the principle of cosine comparison (Adamson and Wedepohl 1956, Humpage and Sabberwal 1965) or sine comparison. The principle of sequence detection is reported by Thakkar and Parathasarathy (1970) where it is shown that the required characteristic may be obtained by detecting the sequence of the selected mixed signals. Thakkar and Parathasarathy (1970) further present the mathematical basis of the relay working on the principle of sequence detection and describes two schemes of practical circuitry of the relay. It is necessary to employ separate phase comparator for every pair of input signals in the first scheme resulting in the costly construction of the relay. The second scheme employs flip-flop circuits in the detection of the sequence requiring less number of circuit components. However, it suffers from the disadvantage that its time of operation increases unduly to two cycles. [ABSTRACT FROM AUTHOR]

In this paper the dispersion relation for rectangular waveguides filled with homogeneous lossy drifting plasma under the influence of infinite longitudinal magnetic field is derived and discussed. The properties of TE modes are found to be the same as those of air-filled guides. However, uniaxial anisotropic drifting lossy plasma has a significant effect on the propagation characteristics of TM modes. A comparison of the effects and physical significance of the changes duo to isotropic and anisotropic plasma models is discussed.
1. Introduction
In recent years plasma-filled waveguides have received considerable attention owing to their applications in microwaves. A general solution for the propagating modes in waveguides completely or partially filled with plasma, taking into account an applied static magnetic field, non-uniform density over the guide cross section and non-vanishing temperature, has not yet been found. It is customary to incorporate the effect of plasma by assuming either an equivalent dielectric constant in the absence of an external magnetic field or an equivalent dielectric tensor with an external applied magnetic field. The nature of electromagnetic wave propagation in waveguides filled with cold stationary plasma under the influence of an external magnetic field was the subject of extensive investigation (Allis et al. 1963). Recently Tuan (1969) and Kalluri (1970) have given some idea of the propagation of electromagnetic waves in waveguides filled with warm and drifting plasma. It is the purpose of the present paper to study the dispersion relation in rectangular waveguides filled with homogeneous drifting lossy uniaxial anisotropic plasma. The strong static magnetic field is assumed to be in the direction of the guide axis. [ABSTRACT FROM AUTHOR]

The role of orthogonal polynomials m obtaining a transfer function whose magnitude or phase approximates that of the ideal low-pass filter characteristic is well recognized. In this paper an attempt is made to generate positive real functions starting from the recurrence relations which are normally used in generating polynomials.
The importance of orthogonal polynomials in approximating a specified frequency response characteristic is well known. For instance, Chebyshev polynomials have been used in deriving a transfer function whose magnitude approximates that of an ideal low-pass filter. Also, the phase of the transfer function given by the inverse of a Bessel polynomial is shown to approximate that of an ideal low-pass filter. Though several polynomials have been successfully used to obtain required transfer functions, no attempts seem to have been made to use them for the generation of positive real functions. In this paper an attempt is made to generate positive real functions starting from the recurrence relations that are usually employed in the generation of polynomials. [ABSTRACT FROM AUTHOR]

In this paper a method of drawing the signal flow graph of an active degenerate RLC network is given. From this signal flow graph the state equations of the network are obtained using Mason's graph gain formula.
The representation of networks in state equation form X(t) = AX(t) + But is advantageous in many respects. Recently Acar (1970) has provided a simple method for the formulation of state equations of active non-degenerate RLC networks using signal flow graph. The method is computationally more simple than earlier methods due to Dervisoglu (1964) and Kuh and Rohrer (1965), but unfortunately this cannot be applied for networks containing degeneracy. The purpose of the present paper is to provide a method for drawing the signal flow graph of an active RLC network containing degeneracy in the form of capacitance loops and inductance cutsets. By eliminating the dynamically superfluous variables with suitable linear equations of constraint due to degeneracies, the signal flow graph of the network may be properly drawn. By inspection of this signal flow graph the A and B matrices are directly obtainable using the graph gain formula. [ABSTRACT FROM AUTHOR]

In a series of papers and reviews Melehy (1964, 1965 a, 1965 b, 1966, 1968, 1970) has proposed an approach to thermodynamics via a somewhat unique definition of equilibrium, and in particular has illustrated his model by an examination of the equilibrium and steady-state conditions in semiconductor p-n junctions.
It is the purpose of the following paper to re-examine Melehy's hypotheses and to show that where his conclusions differ from those more generally accepted that it is due to misconception of semiconductor device principles. [ABSTRACT FROM AUTHOR]

It is well known that the network functions of an active network can be evaluated by means of complete trees or directed trees of its associated graphs. The paper presents and implements a matrix algorithm that generates all the directed trees or complete trees by a digital computer without redundancies due to duplications. The quantitative statistics of eight practical networks is given.
In the topological analysis of a linear active network, the problem of writing down network functions by inspection reduces ultimately to that of finding the set of directed trees or complete trees in the associated graphs. Since directed trees or complete trees of the associated graphs are in one-to-one correspondence with the corresponding major submatrices of certain associated matrices, the problem is equivalent to that of generating all the corresponding major submatrices efficiently. In this paper we shall present quantitative statistics reflecting upon the practicality of generating directed and complete trees based on an improved version of the matrix technique proposed by Mayeda et al. (1968) and Chen (1968). [ABSTRACT FROM AUTHOR]

In this paper an analysis of the first-order distortion to the current distribution in a short single-turn circular coil of high resistivity is presented. Both the in-phase and quadrature components arc given for different axial positions.
1. Introduction
There are several practical situations where short single-turn coils are used; these include induction heaters, plasma machines, magnetic forming of metals and radio-frequency circuits. In most of these applications the inductive impedance of the coil is greatly in excess of its resistive component and the current distribution may be analyzed for the greater part in terms of an infinite conductivity model (Barrault and McCartan 1966).
In other applications such as ohmic heaters and low-frequency air-cored magnetic field coils this situation is reversed and the current distribution is largely governed by the resistive component.
This paper presents an analysis of the first-order distortion to the current distribution resulting in this latter case from a weak inductive component. [ABSTRACT FROM AUTHOR]

The paper presents an active RC network which exhibits selective, all-pass and notch characteristics with simple adjustments of parameters. Two gain-parameters and passive-resistive elements are kept adjustable for this purpose, which also help to obtain variable selectivity and desired center frequency of the filter in the appropriate configurations. Discussions on the Q factor sensitivity of the filters have also been appended.
This paper describes an active RC second-order filter which can be adapted to operate in three different modes. As a band-pass filter it can be designed to have adjustable bandwidth and center frequency, which shows that the circuit may be used as a tuned selective filter. Secondly, depending on the choice of the system parameters, the circuit behaves as an all-pass network with adjustable delay. Finally, it is shown that the circuit operates as a very good rejection filter having continuously adjustable selectivity and notch frequency with no change in the shapes of its transmission characteristics. [ABSTRACT FROM AUTHOR]

The paper describes a circuit containing a junction transistor and a F.E.T. which behave as a one-port voltage controlled negative resistance of adjustable magnitude.
One-port negative resistance circuits, being very useful in synthesis of network functions, filter design and the design of regenerative circuits, have been developed by many authors (Waldmann and Beiri 1955, Indiresan 1959, Nagata 1965, Martinelli 1966). In this paper a new voltage controlled negative resistance circuit employing a transistor and a F.E.T. has been proposed which is different from the existing circuits regarding its network topology. The circuit requires no internal bias. As this circuit utilizes one transistor and a F.E.T., the circuit can be readily fabricated as an integrated module. [ABSTRACT FROM AUTHOR]

The realization of special types of the generalized-immittance converters will be given here using the second-generation current conveyor. Of particular interest in this paper is the new realization of the voltage generalized-immittance converter having conversion immittance function proportional to s. It will be seen that two realizations exist for each converter.
A special type of the current generalized-immittance converter was recently introduced, and used in one of the recent and most attractive RC active network synthesis procedures (Antoniou 1970). Antoniou (1970) used the operational amplifier as the active building block in the realization of the current generalized-immittance converter.
In a recent publication, Sedra and Smith (1970) introduced the second-generation current conveyor (will be abbreviated here as the current conveyor CC) and used it in the realization of some active network elements. The current conveyor is a versatile building block, as it can be used as a current summer, current differentiator, current integrator, current amplifier, etc.
In this paper the simulation of special types of both voltage and current generalized-immittance converters using the current conveyor will be given. [ABSTRACT FROM AUTHOR]

When harmonic oscillators utilizing elements with N-type and S-type voltage/current characteristics (elements with negative conductance or negative resistance) are calculated, usually only the non-linearity of the voltage/current characteristic is taken into account. However, the impedance of these elements is of a complex character, and the non-linearity of the reactive component influences the different modes of operation. This influence may be considerable and in some cases even dominating. If, however, it is taken into account, then the calculation of such systems becomes very difficult. The method used in this paper (Samoylo 1964, 1968) enables these problems to be treated correctly and at the same time considerably simplifies the mathematical calculations.
The results given in the paper may be used when harmonic oscillators utilizing tunnel diodes, Gunn diodes, avalanche diodes, avalanche transistors, unijunction transistors, p-n-p-n-type elements, etc., are studied.
The calculations are made considering the non-linearity of the active and reactive components of the impedance of these elements. The experimental results agree well with the theoretical results. [ABSTRACT FROM AUTHOR]

By inclusion of an external driving force, wave motion of any kind can be characterized by a dispersion function. This function is closely related to the energetic properties of wave motion, and then also to the averaged Lagrangian density. Linear and non-linear wave interaction can be analysed by inclusion of internal driving forces. Normalization procedures for the amplitudes can be avoided and time and space perturbations studied simultaneously. This analysis is further connected to slowly varying amplitudes and quasi-monochromatic waves. This paper presents the above-mentioned method and applies it to linear two-wave coupling, and non-linear three-wave coupling between positive and negative energy waves, and finally to amplitude modulation. The general equations obtained by this procedure are useful for general discussions. The simplicity of the method may prove useful in different applications.
The aim of this paper is to present a new and a simple method for analysis of wave interaction in dispersive media and to apply it on some illustrative problems. Further applications, which are found in plasma physics, microwave components and so on, will be presented later. [ABSTRACT FROM AUTHOR]

This paper describes gallium arsenide varactor diodes which develop effective values of f over 130 GHZ and will operate in double-diode parametric amplifiers at idler frequencies up to 43 GHZ. With such diodes it is possible to build wide band amplifiers which give good low noise performance without refrigeration. For example, an uncooled two-stage amplifier with a bandwidth of 500 MHZ at 26 dB gain gives an overall excess noise temperature at 7-25 GHZ of 85degreesK of which only 60degreesK is due to the varactor.
In recent years low noise parametric amplifiers which combine wide band-widths with high stability have been developed at S.E.R.L. for certain radar and satellite communication receivers. These amplifiers (Gittins et al. 1968) used the Pearson double-diode idler circuit (Pearson and Lunt 1964) as the cornerstone of the design, but the wide bandwidths were achieved by an innovation in which an extra resonant circuit of variable Q is coupled into the Pearson idler loop. Low noise temperature was obtained by cooling the diodes to liquid nitrogen temperature or below. However, refrigeration is unacceptable for many systems and, in particular, requirements at X-band now call for amplifiers with an excess noise temperature below 100degreesK when operating at ambient temperature. This sort of performance needs an idler frequency of at least 40 GHZ and an effective diode quality factor (f) greater than 100 GHZ. This paper describes the design and construction of new diodes which have such characteristics. [ABSTRACT FROM AUTHOR]

In this paper the gradual capture effect on the generation-recombination current in the space-charge region for an asymmetrical junction is studied. The theory is applied to the p-n InSb diodes. At forward bias, when the lifetime increases in the direction from p region to n region, the results we have obtained show that the current increases more rapidly with voltage than in the reverse case.
In this paper we shall take into account the gradual capture effect on the generation-recombination current in the space-charge region for an asymmetrical junction. [ABSTRACT FROM AUTHOR]

Plasma data given previously for the negative glow and Faraday dark space of near-normal cold cathode discharges in neon are supplemented by results, described briefly, for similar discharges without positive column or anode glow. The axial plasma electron concentration curves, which are sharply peaked near the cathode dark space when the cathode rays are strongly attenuated towards the anode, flatten markedly as the attenuation decreases.
The present paper contains a brief account and discussion of selected measurements of this kind made in neon (Grimley 1965). They supplement results for comparable discharges with an anode glow or positive column present, which have been described elsewhere (Woolsey et al. 1969). The critique of techniques given in the latter and in another paper (Emeleus 1969) will not be repeated here, beyond remarking that (a) current drain from the discharge by a probe near space-potential, although it will tend to produce some truncation of concentration maxima, seems unlikely to affect the main features of the results, and (b) it would nevertheless be desirable to repeat the measurements using ion-accelerating rather than space-potential data, although results obtained by the two methods in a similar discharge with rather larger concentrations agree well (Stern 1969). Unless otherwise stated, attention will be confined to the slowest (plasma) group of electrons. [ABSTRACT FROM AUTHOR]

For several years the so-called 'shorted emitter' principle has been used widely to improve the performance of silicon-controlled rectifiers.
In this paper the evolution of the emitter shunt is surveyed, and a review of simple theoretical principles is followed by an account of experiments which substantiate the general theory.
Since the publication of a paper by Aldrich and Holonyak (1959) which outlined a method of improving the temperature and rate of rise performance of the thyristor, many references to this so-called shorted emitter technique have appeared in the literature (Gentry et al. 1964, Gentry et al. 1965, Ruhl 1970, Chu 1970). However, in spite of the fact that the technique is now widely used in the production of commercial thyristors, little detail has been given in many of these references and no comprehensive survey is available.
Over the past few years, in our laboratories, a number of investigations have been carried out, and techniques have been established to make use of this shorted emitter principle.
It now seems an appropriate time to review this important field of semiconductor technology and give a brief account of experiments which have substantiated the theory. [ABSTRACT FROM AUTHOR]

This is the final part of a three-part series on the problem of efficient generation of trees of a graph. In this part of the paper we summarize most. of the existing techniques on tree generation that are based on decomposition and elementary tree and co-tree transformations, and provide a unified theory for their derivation.
In Parts I and II (Chen 1969d, e) we have shown that many of the existing techniques on generation of trees of a graph in the literature, seemingly so different in their appearance, can be formulated in one of the following two ways: the Wang algebra formulation and the matrix formulation. In the present Part III we shall show that the techniques on tree generation, based on decomposition and elementary tree and co-tree transformations, can be deduced from the Wang algebra formulation.
Throughout the paper the symbols n, b, and c are used to denote the numbers of nodes, edges, and components of a graph G, respectively. We denote the rank and the nullity of G by r and m, respectively. Unless specified to the contrary, we assume that G is connected. Definitions of terms used which are not explicitly defined may be found in Part I. [ABSTRACT FROM AUTHOR]

The well-known cyclotron resonance mechanism has been studied and energization of electrons in the magnetosphere has been explored. The relativistic variation of electron mass in the resonance process has been considered and the consequence of neglecting the relativistic electron mass variation has been discussed. At or near resonance the electron motion conforms with the motion of electrons in a potential well. Calculating the shape of the pseudo-potential for the magnetospheric plasma we have calculated the energy gained by the electrons. It is seen that 1 ev electron resonating with the electromagnetic wave (=10 rad sec and E=10 e.s.u.) acquires 1 Mev energy after 188 sec. The geophysical effect of the proposed energization is discussed.
It is well known that resonance of electrons with the electromagnetic waves propagating in the magnetoplasma energize the gyrating electrons. In our earlier paper (Nath and Singh 1970--hereafter referred as NS-I) we discussed the periodic energization of resonating electrons in the magnetosphere. In this paper we relax the requirement in Roberts and Buchsbaum's formulation (1964) and study the synchronous energization of the electrons in the magnetosphere. This is in accordance with the fact that high energy electrons have been detected in the magnetosphere and in the ionosphere. Davydovskii (1963) has suggested that under suitable conditions the charged particles could maintain synchronism with the electromagnetic waves and gain considerable amount of energy. [ABSTRACT FROM AUTHOR]

In this paper we consider how the electric potential varies in space and time during the formation of a plasma sheath. We give the variation of the wall potential in time, the potential profile at various stages of the sheath formation and the variation of the total current at the wall.
In this paper we extend the well-established static theory of plasma sheaths and discuss the growth of a sheath near a plane perfectly absorbing wall. Suppose that we introduce a plane perfectly absorbing sheet of material into a plasma which is electrically neutral and consists of electrons and a single type of singly ionized atoms. The mobile electrons will in general have a much higher velocity than the more massive ions and so initially more electrons than ions will strike the wall, and be absorbed, per unit time. Thus the wall will initially acquire a net negative charge. This charge will repel the electrons approaching the wall from the main body of the plasma and attract the ions. The net charge on the wall will continue to increase until the current density at the wall becomes zero. We wish to investigate the rate of growth of the potential of the wall and the profile of the electric potential at any time on the basis of a simple model. [ABSTRACT FROM AUTHOR]

In some applications it may be desirable to construct an aerial array to radiate minimum energy in a certain angular sector whilst providing high gain in the required direction. In this paper the far field expression for the radiation pattern of a broadside array is reduced to a function of several variables of the inter-element spacing. The element positions are then optimized to correspond to minimum radiation over a specified sector. Experimental results have been obtained in accordance with the theoretical predictions, but difficulty was experienced in achieving small signal measurement near the theoretical minima in the laboratory.
The purpose of the present paper is to show that a similar result is possible in the case of a non-uniformly spaced element array uniformly excited. [ABSTRACT FROM AUTHOR]

Collisions are considered as a drag force in the equation of motion of electrons, and its effect on the wave-particle resonance is shown. Expressions for energy gain and time period of energy oscillations are derived. The role of collisions on the synchronous and oscillatory energy gain and on the time period of energy oscillation for magnetospheric plasma is shown. Energy gain is considerably affected, due to the presence of collisions.
It is well known that electrons resonate with electromagnetic waves propagating through magnetoplasma. In our earlier paper (Nath and Singh 1971--hereafter referred to as NS--I) we discussed the periodic energization of resonating electrons in the magnetosphere. Certain magnetospheric and ionospheric observations have been successfully explained in terms of wave-particle resonance. In NS--I we assumed the collisionless ambient plasma. In this paper we relax the requirement and introduce the effect of collisions in Roberts and Buchsbamn's formulation (1964). This is done in accordance with the fact that most of the gaseous and solid-state plasma are characterized by significant collisional effects. The effect of collisions on wave-particle resonance has been studied in solid-state plasma (Vural and Bloom 1966, and Robinson 1967). In order to interpret some of the magnetospheric and ionospheric results on electron influx pulsations and the co-varying brems-strahlung x-ray flux, we have modified Roberts and Buchsbaum's resonance theory to account for the electron collision frequency. The collisions have been introduced as frictional forces in the equation of motion. With collisions each electron would behave as if it were subjected to a retarding force mvv. It is obvious that the collisions tend to decrease the velocity of the electrons and energy exponentially and eventually limit the energy gain of the resonating electrons. The limit of energy gain arising from the role of collisions is physically more feasible and provides... [ABSTRACT FROM AUTHOR]

This paper attempts to analyze doubly terminated non-symmetrical lattices. The study is restricted to (a) rendering the lattice resistive and (b) the driving-point impedances at the ports to be capacitive and inductive.
In network synthesis the symmetric-lattice structure possesses a main advantage in that any symmetrical realizable two-terminal pair network can be realized as a lattice and, as such, requires only two parameters to characterize such a network. Though some work is done on non-symmetrical lattices (Advani and Reddy 1969, Lee 1963, Miyata 1963), the onus has been on symmetrical lattices.
Hopefully, this paper may lead on to some interesting applications, one such potential application appears to be in the lumped approximation of divergent and convergent exponential lines (Ramachandran 1962). [ABSTRACT FROM AUTHOR]

The phase-space method of calculating electron velocity fluctuations generated by a thermionic cathode is extended to problems encountered in two-dimensional systems. Expressions are derived for volume and current density of the emitted electrons. Numerical results are obtained for the case of a semi-infinite, plane cathode immersed in a constant magnetic field. The two cases of interest, when the field is either parallel or perpendicular to the cathode, are considered separately. A method of reducing the cathode edge effect is discussed in the last section of the paper.
The main object of the paper is to present a method of calculating electron velocity fluctuations and the corresponding volume and current density distributions in systems which are basically two-dimensional in character. [ABSTRACT FROM AUTHOR]

This paper presents a new method of realization of second-degree filters having low-pass, band-pass and high-pass characteristics. Each of the characteristics requires two unity gain non-inverting type amplifiers in addition to passive resistances and capacitances. Details of sensitivity analysis have been reported. This method of realization gives appreciably low Q sensitivity due to the variation of passive elements. But the Q sensitivity due to the variation of the gain of the amplifier becomes a little high. This limits its application in high-Q filters.
This paper gives a new realization procedure for active second-order filters. Each of the band-pass, low-pass and high-pass characteristics requires two unity gain non-inverting amplifiers in conjunction with the passive resistances and capacitances. Details of sensitivity analysis show that the percentage variation of pole Q due to the percentage variation of passive R and C is sufficiently low. But the Q sensitivity due to the variation of amplifier gain is a little high. This dictates that the method will be practically useful in the case of low-Q filters. [ABSTRACT FROM AUTHOR]

This paper describes briefly the ideal characteristics required for tripping for faults within the first zone of a distance relay adapted to the protection of a transmission line. The quadrilateral characteristic on an R-X diagram, which is the ideal characteristic, is obtained using a new hybrid comparison technique. This technique possesses the flexibility of conforming to any desired characteristic by a simple change in the selection of current inputs. The relays are described in their block schematic form.
In this paper the first zone distance relay is considered and the desirable shapes of its characteristics are discussed. A new hybrid comparison technique is used to obtain these desirable characteristics. The comparator models are described in their block schematic form. [ABSTRACT FROM AUTHOR]

Recent studies in non-equilibrium thermodynamics have led to the development of a new general transport theory. Applied to charged systems, this theory makes it possible to separate completely the effects of the processes of diffusion and drift and to calculate the amount of transport work necessary to support a current through each one of such processes, even in the presence of charge-carrier generation or recombination. Thus, considering forward conduction in p-n junctions and heterojunctions to be simply carried by the injection of minority carriers, several non-ohmic terms of transport work have been calculated of which three terms are particularly significant.
This paper explains forward conduction in metal-n Schottky diodes to be caused, like in p-n junctions and heterojunctions, by the injection of minority carriers into the n-type semiconductor. This carrier injection originates from an inversion (p-type) layer which is assumed to be between the metal and n-type semiconductor. Such an inversion layer has been recognized earlier by other workers. Theoretical results, derived by this author in previous papers for p-n junctions and heterojunctions, are found to be accurately in agreement with extensive experimental measurements conducted by several authors on: Au-Si, Pt-Si and Au-GaAs diodes at temperatures ranging from 42 to 433 degrees K. [ABSTRACT FROM AUTHOR]