Showing papers by "City University London published in 1970"

Cash Flows in Networks

Abstract: The concept of maximising present value is applied to the timing of activities in a network. The mathematical form of the problem is that of maximising a nonlinear function subject to linear constraints and can be solved as a succession of linear programmes. By application of duality principles the problem can be treated as a form of maximum value flow problem in which discounted cash flows are distributed along arcs from pay events to receipt events. The solution is aided by the “equilibrium theorem” of dual linear programming in that in the optimum condition flows occur only along arcs whose corresponding activity has zero float. The flows which occur in the optimally scheduled solution are directly proportional to the marginal cost which would be incurred by lengthening the activity corresponding to the arc along which the flow occurs. Some implications derived from the model are discussed and a number of possible applications are proposed.

Preparation and characterisation of high surface area semiconducting oxides

Abstract: The conventional method of preparing doped semiconducting oxides involves solid state sintering at elevated temperatures and the resultant products have a very low surface area (< 1 m2 g−1). This severely limits the activity of semiconducting oxide catalysts, such as lithiated NiO. A cryochemical method based on the freeze drying of mixed salt solutions, followed by low temperature calcining has yielded lithiated NiO of over 60 m2 g−1. DTA, conductivity measurements and chemical analyses confirmed that under these conditions, very uniform mixing between Li2O and NiO is achieved and that Li2O can diffuse into the NiO lattice at about 400° C, as compared to 950 to 1000° C for products prepared by conventional means.

Groups Which are the Union of Three Subgroups

Abstract: (1970). Groups Which are the Union of Three Subgroups. The American Mathematical Monthly: Vol. 77, No. 1, pp. 52-57.

On a new mode of description in physics

Abstract: We explore the possibilities of a new informal language, applicable to the microdomain, which enables such characteristics as superposition and discreteness to be introduced without recourse to the quantum algorithm. In terms of new notions that are introduced (e.g. ‘potentiation’ and ‘ensemblation’), we show that an experiment need no longer be thought of as a procedure designed to investigate a property of a ‘separately existing system’. Thus, the necessity of a sharp separation between the ‘system under observation’ and the ‘apparatus’ is avoided. Although the new language is very different from that of classical physics, classical notions appear as a special limiting case. This new informal language leads to a mathematical formalism which employs the descriptive terms of a cohomology theory with values in the integers. Thus our theory is not based on the use of a space-time description, continuous or otherwise. In the appropriate limit, the mathematical formalism contains certain features similar to those of classical field theories. It is therefore suggested that all the field equations of physics can be re-expressed in terms of our theory in a way that is independent of their spacetime description. This point is illustrated by Maxwell's equations, which are understood in terms of cohomology on a discrete complex. In this description, the electromagnetic four-vector potential and the four-current can be discussed in terms of an ‘ensemblation’ of discontinuous hypersurfaces or varieties. Since the cohomology is defined on the integers the charge is naturally discrete.

Cylindrical and boat-tailed afterbodies in transonic flow with gas ejection

Abstract: The measurements were made in an intermittent ejector driven 9 X 8 in. perforated wall transonic wind tunnel with atmospheric stagnation pressure and Reynolds number of 4 X 10/ft. The model consisted of a 1 in. diam 5 caliber centerbody and interchangeable 2 caliber afterbodies. The centerbody was supported on a pair of 45° swept forward hollow struts (see Fig. la), one strut contained pressure tubes

Isotopic tracer studies of the role of butenes in the combustion of n-butane

Abstract: Studies of the oxidation of n-butane, both in the cool flame and slow combustion regions, show that the principal initial products are butene-1 and butene-2 which are formed simultaneously with much smaller quantities of all the possible C$\_{4}$ O-heterocycles. The analytical results suggest that the same free radical species are responsible for attack on the hydrocarbon over the whole temperature range investigated (315 to 423 degrees C); since the selectivity of attack is low, these are probably hydroxyl radicals. Experiments in which [1-$^{14}$C]butene-1 and [2-$^{14}$C] butene-2 are added to reacting n-butane plus oxygen mixtures make it possible to assess quantitatively the role of the alkenes in the combustion of the alkane. The results show that tetrahydrofuran and 2-methyloxetan are produced entirely by isomerization and subsequent decomposition of butylperoxy radicals but that at least part of the 2-ethyloxiran and 2,3-dimethyloxiran formed result from a reaction involving the addition of HO$\_{2}$ radicals to butene-1 and butene-2 respectively. The importance of butenes in the oxidation of n-butane is demonstrated by the fact that after 50 s reaction at 315 degrees C, at least 35% of the initial alkane has been converted to the two conjugate alkenes and about 60% of these compounds has reacted further. The results show that in general butene-2 is a more reactive intermediate than butene-1.

The Dynamics and Control of Chemical Processes in Man

Abstract: The paper reviews the various control mechanisms to be found in chemical reactions occurring in man. The concept of compartmental analysis is discussed and the unit processes of biochemistry are considered, e.g. enzymic reactions, expanding systems, transport systems. Modelling techniques are discussed with particular reference to plasma protein metabolism and bilirubin metabolism.

Training for Information Science

Abstract: Education in information Science is now well established a a postgraduate level in Great Britain, and has recently also been started to a graduate level. The scope of the subject is seen as both practical and theoretical,and as a professional training. The position up to 1965 was fully surveyed by me in a previous report. New developments during the last five years have taken place almost only in Great Britain; of education abroad—apart from an increase in the number of courses, mainly of short duration, or only part of more general courses; and, in Europe, at relatively lower levels—there is little new to record. In Europe the field is more generally known as documentation, and tends to correspond rather more with what in England is called special librarianship. In the United States the term ‘information science’ is usually defined as the purely theoretical science of information and information handling, especially by means of computers; the practical aspects have been called ‘information technology’, w...

The imperial idea in South Africa

Abstract: I F there was one man who realized that Milner's ideals for the future of South Africa after the Boer War were doomed to failure, it was Milner himself. He had looked forward to a South Africa securely British, an end to be secured by immigration, and with the Boers gradually transformed into loyal members of the Empire by means of education. English was to be the medium of instruction in the schools, but more than this could be done in them.

2,4-diethylquinoline - an extension of the combes synthesis

Abstract: (1970). 2,4-DIETHYLQUINOLINE - AN EXTENSION OF THE COMBES SYNTHESIS. Organic Preparations and Procedures: Vol. 2, No. 4, pp. 305-308.