Positive Resistances Research Articles

The Microcomputer as a Psychotherapeutic Aid

Abstract This paper describes the efforts of a psychologist to use word processing, spreadsheet, and graphics programs as psycho-therapeutic aids with chronic psychiatric patients. The basic goal was to enhance users' feelings of mastery and self-esteem. Individual and group interventions are briefly described as well as positive responses and resistances to computer use. No differences in computer utilization were found based on diagnosis, age, or educational level. Future areas of research are delineated.

On the equivalence of spatial and temporal stability for translation invariant linear resistive networks

A fundamental relationship between spatial and temporal stability is explored for a class of translation-invariant linear resistive networks. These networks appear to have great promise for the high-speed linear filtering of two-dimensional spatially sampled analog data such as imagery. In general, networks designed for such applications require both positive and negative resistances. It is proved that such networks, when terminated in a certain reasonable manner, are temporally asymptotically stable in the presence of arbitrary parasitic capacitances whenever the network's underlying spatial response (convolution) is bounded-input-bounded-output stable.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Ideal rectifier n‐ports are solvable

AbstractIt is proved that an n‐port composed of ideal transformers, gyrators and ideal rectifiers has a unique solution for the port variables when it is excited by generators in series with strictly positive resistances. the multiplicity of solutions for the internal variables is discussed. Connections are established with the theory of linear inequalities and with the coloured branch theorem of graph theory.

Realizability and synthesis for infinite grids of positive resistances

A semi-infinite resistive grid can be characterized from its boundary conditions by a certain function <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F(z)</tex> of the complex variable <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</tex> . We establish herein both pole-zero and pole-residue realizability conditions that insure that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F(z)</tex> does represent a resistive grid. We also show how that grid can be synthesized from a realizable <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F(z)</tex> . These results are established for both two-dimensional and three-dimensional grids.

Determination of Available Power from Resistive Multiports

The concept of available power (P_{A}) is extended to multiports. A theorem is proved, which gives a necessary condition for P_{A} to be achieved with all positive load resistances for the case of resistive-reciprocal multiports. Based on the theorem, a procedure is outlined for determining P_{A} for resistive multiports. The method requires the solution of simultaneous linear equations only. Two examples are given.

An active RC synthesis and design of filters using voltage-to-current transducers†

This paper presents an active RC synthesis and design of filters on the basis of nodal admittance matrix. The method implies the construction of equivalent (2 × 2) nodal admittance matrices satisfying the voltage transfer-functions of Type 1 and Type 2. Each of the matrices so obtained is found to be realized by positive resistances, capacitances and an active element VCT. The overall transfer-function is obtained by a cascade of Type 1 and Type. 2 networks.

Bounds on impedance functions of R, ± L, ± C, T networks

It is shown that if Z ij(s) is an open circuit impedance of a two-port network N containing positive resistances, positive and negative inductances, positive and negative capacitances, and ideal transformers, then Z ij(jw) satisfies the inequality | Z ij(jw) − R ijo + R ijs 2 | ≤ (R ijo − R ijs) 2 (R jjo − R jjs) 2 (i,j = 1,2) for all real ω, where R ijo = the impedance Z ij of N when all reactive elements are open circuited, and R ijs = the impedance Z ij of N when all reactive elements are short circuited. The inequality is useful for finding bounds on the magnitude, the phase angle, and the real and the imaginary parts of the Z ij(jw).

Dumiload: A Variable-Radiation-Impedance Simulator

A wide range of radiation load impedances for a transducer element has been created by a laboratory device. This range included all the radiation impedances that exist for any of the transducers of a large planar array of over 400 elements. The device is called DUMILOAD, which is a contraction of DUmmy Mechanical Impedance LOAD. The DUMILOAD consists of a transducer terminated with an electrical impedance. A purely passive electrical impedance is sufficient to create positive radiation resistances. The DUMILOAD transducer is cemented face to face with a test transducer. The radiation impedance of the test transducer is controlled by adjusting the electrical impedance terminating the load transducer. The DUMILOAD is an existing research tool and has been of great value for high power transducer testing at NEL. The procedures necessary to create a desired radiation impedance are presented and a simple but precise method for measuring directly the radiation impedance achieved is described.

Transfer Function Synthesis of RC Tunnel-Diode Networks

This paper presents several procedures for the synthesis of various transfer functions by means of networks containing positive resistances, positive capacitances, and a minimum number of ideal tunnel diodes (represented by a parallel combination of a positive capacitor and a negative resistor). Use of tunnel diodes is shown to allow realization of arbitrary transmission zeroes by means of grounded RC tunnel-diode networks. The tunnel diode may be employed either to improve the gain obtainable by passive realization techniques or to synthesize transfer functions that are not <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</tex> realizable. In addition to a cascade synthesis technique to realize right-half-plane transmission zeroes, a method is presented to realize any voltage transfer ratio with unrestricted transmission zeroes by employing a single tunnel diode.

The realizability of tunnel-diode-RC networks

The necessary and sufficient conditions for the physical realizability of one-port structures obtained by imbedding several nonidentical tunnel diodes (represented by a parallel combination of a positive capacitor and a negative resistor) in a network of positive resistances and positive capacitances are presented in this paper. Some new results concerning ±RC networks are also included, in addition to an alternate simpler derivation of Bello and Kinariwala's results regarding such networks.

Some Generalities of the Transit-time Mode for Two-barrier Devices†

ABSTRACT Active devices having injecting and collecting electrodes, such as thermionic tubes, transistors, metal-interface amplifiers, etc., have some common properties. The propagation of an injected current wave gives rise to negative and positive resistances, inductances and capacitances. In all such devices negative resistances are available not only at low frequencies, but at high frequencies as well. The interfaces displaying those characteristics can be formed of metals, insulators and semiconductors.

Theory of a Negative-Resistance Transmission Line Amplifier with Distributed Noise Generators

A transmission line with distributed positive and negative resistances as well as with distributed noise generators is treated. Gain and noise factor are derived as a function of boundary conditions, matching conditions and distributed noise. It is found that low-noise amplification can be achieved on such a line provided the line is characterized by high gain per unit length, high total gain, good matching, and low distributed noise. A distortionless active line for such low-noise amplifiers appears attractive.

Regeneration in Coupled Circuits

1-The simple theory of regeneration in a single oscillatory circuit is developed, both when the oscillatory element is in the plate circuit and in the grid circuit of the regenerating tube. 2-The theory of couple circuits having positive resistances is reviewed and illustrated by means of space models for the secondary current. The use of sections of the model for determining graphically and for visualizing the variations of secondary current as the primary or secondary circuits are changed or as the impressed wave length is varied, is given. The positions of the two peaks of max. max. secondary current, when the coupling is greater than critical, is shown to depend upon the relative values of R/(Lω <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> ) = η for the two circuits. When the ratio of η <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> /η <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> is unity, the two peaks are symmetrically located on the space model with respect to the primary and secondary axes, otherwise the space model is unsymmetrical. 3-The theory of regeneration in coupled circuits is developed. It is shown that regeneration in the secondary circuit affects only the impedance of that circuit and may make the equivalent resistance of that circuit zero or negative. The first case taken up assumes the regeneration to be constant, so that the theory for this case is the theory for coupled circuits, one of which has a negative resistance. The boundary equation between oscillation and non-oscillation is derived and plotted.