Showing papers by "City University London published in 1972"
168 citations
TL;DR: In this article, the electrical conductivity and activation energy for conduction of the cobalt-iron oxide series were determined, and used to define the electronic structure of this series in conjunction with theoretical considerations based on crystal field theory.
Abstract: Seven ultrafine samples (125 to 60 m2/g) of the cobalt-iron oxide series, Co x Fe3−x,O4, with 0≤x≤3, were prepared by co-precipitation of the metal hydroxides, followed by dehydration of the hydroxide at 100† C. X-ray and chemical analyses confirmed that true spinels were formed. The electrical conductivity and the activation energy for conduction of the powders were determined, and used to define the electronic structure of this series in conjunction with theoretical considerations based on crystal field theory.
33 citations
TL;DR: It is shown how an increase in surface potential of cells, on malignant transformation, can (by way of the spontaneous segregation effect) be a necessary precursor to metastasis.
31 citations
TL;DR: The factors influencing the spatial distribution of metal catalyst on catalyst substrates have been investigated by studying the wettability, drying process and chemical interaction between the catalytic metallic salt solution and substrate, using AgNO3/graphite as a model system.
Abstract: The factors influencing the spatial distribution of metal catalyst on catalyst substrates have been investigated by studying the wettability, drying process and chemical interaction between the catalytic metallic salt solution and substrate, using AgNO3/graphite as a model system. AgNO3 reacts with graphite at temperatures above 100°C and hence very uniform dispersion of Ag on graphite is achieved by simple thermal treatment. On the other hand, for other systems which do not involve chemical reaction, such as H2PtCl6/graphite, freeze-drying gives better results. Teflon bonded electrodes prepared from impregnated catalysts containing 10% Ag on C gave 800m A/cm2 at 0·84 V for the reduction of oxygen in 5nKOH at room temperature.
20 citations
TL;DR: Magnitude estimation scales of foveal luminosity (subjective brightness) of two subjects were studied for ranges of preadaptation and contrast luminances and inter-subject differences cast doubt on the use of this technique in establishing fundamental Psychophysical Laws.
9 citations
TL;DR: A proof is given of a method proposed by Lackey and Meltzer for determining the selection of Rademacher functions that must be combined to generate a specified Walsh function.
Abstract: A proof is given of a method proposed by Lackey and Meltzer [2] for determining the selection of Rademacher functions that must be combined to generate a specified Walsh function. The method provides a convenient way of digitally controlling a Walsh function generator.
9 citations
TL;DR: In this paper, the ion production probabilities in an argon discharge plasma are studied under various conditions, and the radial behavior of the probabilities are discussed for the unperturbed discharge, and for the case where an ion beam is being extracted.
7 citations
01 Nov 1972
TL;DR: In this article, the authors describe the techniques that have been developed in attempts to photograph in detail the events occurring during the electrical breakdown of an insulating liquid, as the breakdown occurs at random times, it has been necessary to develop a means of synchronizing the recording system with this breakdown.
Abstract: This paper describes the techniques that have been developed in attempts to photograph in detail the events occurring during the electrical breakdown of an insulating liquid. As the breakdown occurs at random times, it has been necessary to develop a means of synchronizing the recording system with this breakdown. The techniques discussed make it possible to photograph the discharge in the streak mode with a time resolution of only a few picoseconds.
4 citations
TL;DR: In this paper, the incorporation of electrolyte-phobic material into gas diffusion electrodes enhances their performance and the principles governing the choice of the electrolytephobic materials in molten carbonate electrolyte are discussed.
Abstract: The incorporation of electrolyte-phobic material into gas diffusion electrodes enhances their performance. The principles governing the choice of electrolyte-phobic materials in molten carbonate electrolyte are discussed. Contact angle measurements of molten NaLiCO3 on materials which have hexagonal layer-like structures confirmed that providedγ
LV
γ
SV, the contact angle will be greater than 90°. Of the materials tested (C, BN, BaO.6.Fe2O3, PbO.6Fe2O3), only C possessed adequate corrosion resistance. Electrolyte-phobic anodes, prepared by incorporation of graphite fibres into the electrocatalyst mixture, significantly reduced concentration polarization and paste electrolyte cells using such electrodes gave 160 mA/cm2 at 0.6 V on 80% H2/20% CO2 fuel at 600°C, as opposed to 80 mA/cm2 for conventional cells.
3 citations
TL;DR: In this article, a brief survey is given for the method of impulse analysis of scalar systems to show the distinct advantages of time-domain infinite matrices (t.i.m.) methods.
Abstract: A brief survey is given for the method of impulse analysis of scalar systems to show the distinct advantages of time-domain infinite matrices (t.d.i.m.) methods. To tackle the problem of describing and manipulating multivariable systems by these techniques. an extension of the algebra of lower semi-infinite matrices to the multivariable case is developed. Of special importance in this respect are now recursion formulae for inverting stationary and non-stationary impulse response matrices of any dimensions. It is shown that for stationary matrices of dimensions n× n × ∞. the adjoint matrix has to be evaluated at the first sampling instant only. In terms of this evaluation the inverse matrix is generated at any sampling instant by carrying out simple algebraic operations (i.e. addition and multiplication). For non-stationary matrices similar conditions arc derived. The formulae of this paper are useful for the solution of a variety of problems in functional analysis. A numerical example is given to illustra...
3 citations
TL;DR: In this article, the concept of 3s was introduced and generalized to a class of groups called residually central groups, which are defined as (s, Q, Do)-closed classes of groups.
Abstract: In [21, Durbin considered a class of groups which he called residually central groups, and Ayoub [1] has also studied this class. A group G is said to be residually central if whenever x is a nontriviat element of G there exists a normal subgroup N of G such that x~_N and [x, G1
TL;DR: This application is just one example of the general case in which the time duration to be multiplied is a function of a variable to be measured.
Abstract: Various time-duration multiplier systems have been developed and discussed. They have attractive features for on-line computing systems, where the input data are in terms of time durations. These systems which rely on repetition of a time duration can be used as advanced, sensitive sensors with discrete signal output. This application is just one example of the general case in which the time duration to be multiplied is a function of a variable to be measured.
TL;DR: In this article, the interaction of two injection diodes, mounted in a closed-loop liquid system, has shown that a characteristic fluctuation of the injected currents can occur, and an attempt is made to explain this phenomenon by considering the electrically induced liquid flow patterns that could be present in the test cell.
Abstract: A study of the interaction of two injection diodes, mounted in a closed-loop liquid system, has shown that a characteristic fluctuation of the injected currents can occur. An attempt is made to explain this phenomenon by considering the electrically induced liquid flow patterns that could be present in the test cell.
TL;DR: Hunt and Tanner as mentioned in this paper investigated the waves generated by a steadily moving two-dimensional pressure distribution, which was zero ahead of the disturbance and a constant p0, tehind it, these regions being joined smoothly by a cubic function.
Abstract: In a recent paperHunt andTanner [3]2) investigated the waves generated by a steadily moving two-dimensional pressure distribution, which was zero ahead of the disturbance and a constantp0, tehind it, these regions being joined smoothly by a cubic function. Only those solutions with supercritical flow in both regions were considered, these were found to lead to an asymmetric solitary wave.