Showing papers by "Brunel University London published in 1973"
TL;DR: Gold catalysts for the hydrogenation and isomerization of olefins have been obtained by the thermal decomposition of chloroauric acid supported on silica and alumina.
Abstract: Gold catalysts active for the hydrogenation and isomerisation of olefins have been prepared by the thermal decomposition of chloroauric acid supported on silica and alumina. The activity depends critically on the concentration of gold in the catalyst. This article considers the implications of these results and their possible industrial applications.
149 citations
TL;DR: In this article, several approaches have been made to the theoretical study of thermal expansion of composites, ranging from the empirical, to sophisticated analyses based on applied mechanics, after which the available experimental data are examined in the light of current theory.
Abstract: In the past 25 years, several approaches have been made to the theoretical study of thermal expansion of composites. These approaches range from the empirical, to sophisticated analyses based on applied mechanics. The alternatives are discussed in the following paper, after which the available experimental data are examined in the light of current theory. The approach of Kerner and similar workers shows reasonable success for those systems where the dispersed particles can be treated as spheres, but this case is of limited technological interest. On the other hand, the equation due to Turner most closely represents those systems in which the fillers are fibrous or plate-like in nature. Apart from particle shape, it appears that any general theory must take into account a number of physicochemical variables which have hitherto been omitted.
115 citations
TL;DR: The flexibility of this technique is examined through experiments with different branching and subproblem selection strategies, and the efficacy of these various heuristics is assessed.
Abstract: The branch and bound method of solving the mixed integer linear programming problem is summarized. The flexibility of this technique is examined through experiments with different branching and subproblem selection strategies, and the efficacy of these various heuristics is assessed.
92 citations
TL;DR: In this article, a procedure for the design of an observer of minimum order with arbitrary dynamics to provide a specified linear functional of the state vector of a linear system is described, and a procedure is described for the selection of a minimum-order observer of arbitrary dynamics.
Abstract: A procedure is described for the design of an observer of minimum order with arbitrary dynamics to provide a specified linear functional of the state vector of a linear system.
78 citations
TL;DR: Adult Schistosoma mansoni, which had matured in mice, were rapidly killed in vitro by an immune reaction consisting of three components: monkey antisera to mouse erythrocytes; heat-labile factors which are presumed to be complement; and peptoneactivated monkey peritoneal macrophages.
74 citations
01 May 1973
TL;DR: In this article, the surface area of argon and nitrogen adsorption at −196°C was determined on various porous and nonporous silicas, which had been well characterized in previous studies.
Abstract: Argon and nitrogen adsorption isotherms at −196°C were determined on various porous and nonporous silicas, which had been well characterized in previous studies. The corresponding isotherms on each nonporous solid run nearly parallel over the middle range of p p 0 , but the isotherms on the microporous silica cross at p p 0 ∼ 0.1 . Surface areas have been calculated from the isotherms by means of the BET method and the α s -method. To apply the latter method to the argon isotherms it has been necessary to express the new standard adsorption data in the reduced α s form, as has been done previously with nitrogen. Deviations of the α s -plots from linearity are explained in terms of micropore filling and capillary condensation. In the absence of micropore filling, the surface areas calculated from the slope of the α s -plots are in good agreement with the corresponding BET -areas, provided that the cross-sectional area of argon in the BET monolayer is taken as 18.2 A 2 . Micropore filling causes a distortion of the isotherm in the BET range, the effect being greater with argon than with nitrogen and resulting in a decrease in the apparent cross-sectional area of argon.
70 citations
TL;DR: The history of the discovery and naming of the three naturally occurring isotopes of element 91 is outlined in this paper in order to eliminate contradictions to be found in the literature, and information about the nineteen isotopes now known is listed.
Abstract: The history of the discovery and naming of the three naturally occurring isotopes of element 91 is outlined in order to eliminate contradictions to be found in the literature. Information about the nineteen isotopes of protactinium now known is listed.
51 citations
01 Feb 1973
TL;DR: In this article, the effect of relative phase shift insertion between a synchronous machine and its associated power system was investigated, and a method of obtaining a change in the effective rotor-excitation angle, and thereby the power transfer, was described.
Abstract: Computational studies of the transient stability of a synchronous machine connected to an infinite busbar by a double-circuit transmission line are used to illustrate the effect of relative phase-shift insertion between the machine and its associated power system. This method of obtaining a change in the effective rotor-excitation angle, and thereby the power transfer, is described, together with an outline of possible methods of implementation by a phase-shifting transformer in a power system.
37 citations
TL;DR: In this article, a method for numerical solution of harmonic mixed boundary value problems in simply connected domains is described, which consists of three successive conformal transformations of which the first is performed numerically.
Abstract: A method is described for the numerical solution of harmonic mixed boundary value problems in simply-connected domains. The method consists of three successive conformal transformations of which the first is performed numerically. In particular the method is applied to problems, defined in polygonal regions, containing re-entrant cornes at which boundary singularities occur.
29 citations
TL;DR: A brief survey of plastics materials suitable for possible use in bearings is given in this paper, where the technical aspects of the materials, in terms of their physical and chemical properties, as well as fabrication adn material costs are considered.
23 citations
TL;DR: In this paper, the authors extended the interpretation of creep as an evolutionary Markov process, involving a distribution of energy-barrier heights governing dislocation movement, to encompass work-hardening under increasing stresses, by making explicit allowance for the operation of dislocation sources.
Abstract: The interpretation of creep as an evolutionary Markov process, involving a distribution of energy-barrier heights governing dislocation movement (Feltham 1968), is extended to encompass work-hardening under increasing stresses, by making explicit allowance for the operation of dislocation sources. The widely observed, linear, work-hardening law, derivable from the model, is shown to imply the strain invariance of the normalized distribution of the energy-barrier levels. This invariance appears to be a consequence of a mode of `microdeformation' in which the rate of storage of `elastic' energy with respect to strain tends towards a minimum.
TL;DR: In this article, the effects of phosphorus content on the friction and wear characteristics of grey cast iron were studied using a pin on ring machine, and critical speed transitions were related to the physical properties of iron-phosphorus alloys.
TL;DR: In this article, a single apparatus is described which can be used to measure changes in each of the three electro-optic properties indicated in the title of the paper, i.e., birefringence, dichroism, and optical rotation.
TL;DR: Addition of dimethylnitrosamine to rat liver microsomal suspensions increases the rate of NADPH-linked lipid peroxidation and interacts with cytochrome P-450 as shown by the use of difference spectra, and the stimulation of lipidperoxidation probably depends upon metabolism of the dimethylNitrosamine at this site.
Abstract: 1. Addition of dimethylnitrosamine to rat liver microsomal suspensions increases the rate of NADPH-linked lipid peroxidation.2. The stimulatory effects of dimethylnitrosamine on microsomal lipid peroxidation are decreased by inhibitors of microsomal oxidative drug metabolism and by promethazine, but are not altered by the substitution of the NADPH by an equimolar concn. of NADH.3. Dimethylnitrosamine interacts with cytochrome P-450 as shown by the use of difference spectra, and the stimulation of lipid peroxidation probably depends upon metabolism of the dimethylnitrosamine at this site.4. Results are compared and contrasted with previous data on the stimulation of lipid peroxidation by CCl4.
TL;DR: Two methods of simplification can be used, quantization and what the authors have termed the two-point difference method as discussed by the authors, and some of the implications and advantages of these techniques are discussed.
Abstract: General purpose correlators are too expensive for flow metering applications and do not give a velocity measurement directly. Two methods of simplification can be used, quantization and what the authors have termed the two-point difference method. Some of the implications and advantages of these techniques are discussed.
01 Apr 1973
TL;DR: In this article, aqueous sepiolite suspensions were used to study the effect of electric birefringence on rod-like particles in conducting media and found that the repetitive field promoted association of the rodlike particles, probably due to the field induced displacement of mobile charges associated with the solvent or surface properties of the particles.
Abstract: Following a brief summary of the nonregular responses in the literature from pulsed electric birefringence experiments, results are presented of a study on aqueous sepiolite suspensions by this experimental method. The study revealed novel transient responses which varied with repetitive pulsing of the suspension. The behavior indicated that the repetitive field promoted association of the rodlike particles, probably due to the field induced displacement of mobile charges associated with the solvent or surface properties of the particles. The study indicates the value of not neglecting unusual traces, the need for a suitable and complete electric birefringence theory in terms of mobile charge effects, and the need for caution when studying particle suspensions in conducting media.
TL;DR: In this article, eight bis complexes between manganese (II) and 1:10 phenanthroline [Mn (phen) 2 X 2, where X = F, Cl, Br, I, CN, NCO, NCS or NCSe] have been synthesized and characterized by measurement of their magnetic moments, vibrational spectra and X-ray powder diffraction patterns.
TL;DR: In this paper, a procedure is described which enables specified poles and zeros of a transfer function of a linear system to be obtained by using proportional state feedback to two inputs in a restricted class of problem.
Abstract: A procedure is described which enables specified poles and zeros of a transfer function of a linear system to be obtained by using proportional state feedback to two inputs in a restricted class of problem.
TL;DR: In this article, the adsorption of water vapour on a microporous carbon black has been studied by measurement at 25°C of its isotherm, and the heat of immersion in water of samples charged with different amounts of water vapor.
TL;DR: It is shown that unpolarized light yields as much molecular information as the polarized methods used hitherto.
Abstract: A comprehensive theory is developed in terms of the principal molar extinction coefficients (∊ii) of rigid, isolated, rodlike macromolecules when subjected to orienting force fields. The theory embraces the conventional transverse parallel and perpendicular arrangements and the novel longitudinal dichroism method where the light beam and applied field traverse the system concomitantly. Both transverse and longitudinal measurements are considered when the initial light beam is unpolarized. It is shown that unpolarized light yields as much molecular information as the polarized methods used hitherto. Equations also are given in terms of a single repeating chromophore (∊0) as if at a specific direction (α) to the molecular backbone.
TL;DR: An independent series of experiments have failed to confirm the reported schistosomicidal effect of injections of rhesus monkey stromata and other erythrocyte preparations in infected mice, and it is suggested that the most likely explanation is accidental contamination with bacteria known to kill adult schistsomes in vivo.
TL;DR: In this article, the results of cutting tests performed with a tool which is executing sinusoidal oscillations normal to the mean cutting direction are given and these are compared with deductions from a previously described theory of dynamic cutting.
TL;DR: In this paper, the inherent disadvantages of dc motor drives are studied by considering a separately excited dc motor fed from a single-phase thyristor converter and a novel current control scheme is outlined which can restrict the amplitude of the current close to its average value and make current continuous over a wide range of operation.
Abstract: Solid state dc motor drives are becoming increasingly popular. The inherent disadvantages of such drives are studied by considering a separately excited dc motor fed from a single-phase thyristor converter. The discontinuous and highly rippled armature current in solid state dc drives affect the commutating capability of the dc motor and its static and dynamic performances. A novel current control scheme is outlined which can restrict the amplitude of the current close to its average value and make current continuous over a wide range of operation. This converter-motor system with current-control-scheme is simulated on an analog as well as on a digital computer. The system is found to be potentially capable of providing various useful torque-speed characteristics without any change in the field circuit. Experimental results demonstrate the feasibility of the system.
TL;DR: In this article, the distribution of rank statistics under Lehmann alternatives when sampling is censored on the occurrence of a given order statistic in one of the samples is presented. But the results of these types occur, for example, in life testing situations where testing time may be costly.
Abstract: Several recent papers have considered the distributions of commonly used rank statistics for the two-sample problem under the nonparametric Lehmann alternative that one underlying distribution is a power of the other. Shorack (1 966) presented recursive expressions for generating the distribution of the Mann-Whitney statistic. Steck (1969), dealing with Smirnov two-sample tests, gave a determinant form for the distribution of the one-sided Smirnov statistic under the Lehmann alternative. Davies (1971) compared some small and large sample properties of a Lehmann test with a test proposed by Savage (1956) for the two-sample problem. Here we present results for the distributions of some rank statistics under Lehmann alternatives when sampling is censored on the occurrence of a given order statistic in one of the samples. Shorack (1968) gave recursive formulae for the distributions of other nonparametric test statistics when censoring is based on the occurrence of a given order statistic in the combined samples. Censoring of these types occur, for example, in life testing situations where testing time may be costly. We first consider the distribution of a linear function of the ranks in a given sample and establish some difference relations. These are then used to generate the power of the median and precedence tests and to establish recursive relations for the distribution of a modified Wilcoxon statistic. Finally, the distribution of the censored one-sided Smirnov statistic is derived and used to obtain some new results for the case when the two populations have identical distributions.