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Showing papers by "City University London published in 1987"


Journal ArticleDOI
TL;DR: In this paper, maximum entropy sampling is used to sample the maximum entropy of a set of maximum entropy samples from a single maximum entropy sample set, and the sample set is used for maximum entropy estimation.
Abstract: (1987). Maximum entropy sampling. Journal of Applied Statistics: Vol. 14, No. 2, pp. 165-170.

553 citations


Journal ArticleDOI
TL;DR: The results support a model in which a composite prototype for the conjunction is formed as the union of the constituent attribute sets, subject to two constraints: attributes must have a sufficiently high average importance across the two concepts and necessity and impossibility of attributes is always inherited.
Abstract: Attributes defining pairs of concepts (e.g., SPORTS-GAMES) and their conjunctions (e.g., SPORTS THAT ARE ALSO GAMES) were generated and rated for their importance for defining each concept and conjunction. The results support a model in which a composite prototype for the conjunction is formed as the union of the constituent attribute sets, subject to two constraints: (1) attributes must have a sufficiently high average importance across the two concepts, and (2) necessity and impossibility of attributes is always inherited. In regression analyses, those concepts identified by Hampton (1985b) as being dominant in determining item typicality in conjunctions were again dominant in determining attribute importance and also had greater numbers of important attributes. There was limited evidence of noncompositionality for familiar concept conjunctions. Finally, degree of conflict between the attributes of one concept and those of the other had an independent effect on attribute importance for conjunctions.

341 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a review with dense phase gas tranmission systems of particular interest, briefly developing the basic equations without such assumptions and including the effects of wall friction and heat transfer.

154 citations


Journal ArticleDOI
TL;DR: In this article, the authors provide a physical background to the subject of viscous-inviscid interactions (VII) and provide a discussion of some relevant features of integral and differential methods for turbulent boundary layers.

129 citations


Journal ArticleDOI
TL;DR: The once distinct and independent theories of adhesion have been losing their isolation and converging as mentioned in this paper, and they are losing their importance and becoming more and more convergent with time.
Abstract: The once distinct and independent theories of adhesion have been losing their isolation and converging. Ideas of the effects of surface roughness, once dismissed as irrelevant except in the case of textiles, have been revised; albeit on a smaller scale as details of surfaces have been revealed by sophisticated techniques. Electrostatic interactions across an interface have been more deeply explored and their significance recognised and expounded. Diffusion of groupings and chain segments within a polymer have been related to the possibilities of interaction with a variety of surfaces. Perhaps most important, theories of adsorption have been extended in depth. The precise nature of the molecular interactions have been recognised and quantified. In doing this the contribution of diffusion and elastoplastic phenomena have been integrated. These developments are collated and analysed to present the present understanding of the concepts.

76 citations


Journal ArticleDOI
TL;DR: The paper concludes that the original goal of the REQUEST project to produce a predictive quality model was unrealistic, but that a quality system incorporating prediction, analysis and advice is feasible.
Abstract: This paper considers the approach taken by the ESPRIT-funded REQUEST project to measuring, modelling and predicting software quality. The paper describes previous work on defining software quality and indicates how the work has been used by REQUEST to begin the formulation of a constructive quality model (COQUAMO). The paper concludes that the original goal of the project to produce a predictive quality model was unrealistic, but that a quality system incorporating prediction, analysis and advice is feasible.

75 citations


Journal Article
TL;DR: The results show, firstly, that the cavernous plexus consists of a mixture of sensory and autonomic nerves (sympathetic and parasympathetic) and, secondly, that afferents of the internal carotid artery and rostral circle of Willis and those to the basilar artery and caudalcircle of Willis are distributed separately.
Abstract: Two or three or sometimes more fine intracavernous branches were traced from the ophthalmic nerve using serial section reconstruction and induced nerve degeneration. They joined the cavernous plexus and were distributed forward with autonomic nerves to the adventitia of the internal carotid artery, emerging from the sinus with the artery. A strong recurrent branch from the plexus joined the abducent nerve, passed back and left the nerve at pontine level to innervate the basilar artery and the caudal circle of Willis. The recurrent nerve was absent from one side of two animals and showed asymmetry in others. No branch issued intracranially to the plexus from the maxillary nerve, but in the pterygopalatine fossa the orbitociliary branch of the maxillary nerve gave off one or two filaments that re-entered the cranial cavity through the medial infraorbital fissure and joined the cavernous plexus. Their content augmented the ophthalmic afferent distribution. All plexus branches with trigeminal fibres also contained autonomic fibres. The results show, firstly, that the cavernous plexus consists of a mixture of sensory and autonomic nerves (sympathetic and parasympathetic) and, secondly, that afferents of the internal carotid artery and rostral circle of Willis and those to the basilar artery and caudal circle of Willis are distributed separately.

66 citations


Journal ArticleDOI
TL;DR: In this article, it is argued that contemporary composers must take account of these consequences if their music is to be comprehensible, and that they must take into account these consequences.
Abstract: Music is organized hierarchically in a network of interconnected levels. Different levels demonstrate structural properties of different types, and are notated in music with differing degrees of explicitness. The lowest level consists of continuously variable expressive properties, while the middle and top levels encompass discrete canonical properties. Contemporary music has cast this division into doubt by weakening or abandoning metrical structures and the discrete categories of duration that go with it, and by calling into question the distinction between structure and expression. Since research indicates that meter plays a vital role as a cognitive framework within which to organize rhythm perception and performance, far‐reaching consequences flow from contemporary compositional developments for the perception of both structural and expressive aspects of rhythm in contemporary music. It is argued that contemporary composers must take account of these consequences if their music is to be comprehensibl...

63 citations


Journal ArticleDOI
TL;DR: In this article, the type of statistical techniques that will be required to formulate, evaluate and use the proposed REQUEST constructive quality model (COQUAMO) are discussed in terms of the probable nature and mode of use, the requirements for model and metric validation, and the problems associated with software metrics data.
Abstract: This paper discusses the type of statistical techniques that will be required to formulate, evaluate and use the proposed REQUEST constructive quality model (COQUAMO). Statistical techniques are evaluated in terms of the probable nature and mode of use of COQUAMO, the requirements for model and metric validation, and the problems associated with software metrics data. Examples of preliminary evaluation of the proposed statistical techniques are given using genuine software metrics data.

57 citations


Journal ArticleDOI
TL;DR: The study reveals the extent of subject searching activity, and suggests that this may have been underestimated in previous studies, and proposes that a future online searching environment will encourage a more truly interactive approach to subject searching.
Abstract: Searching behaviour in a university library is studied using a wholistic approach, encompassing the use of bibliographic tools and shelf browsing. The present study is designed as the first half of a ‘before and after’ study to permit the evaluation of the impact of a future online catalogue on users' searching behaviour. A combined methodology was devised: searchers were encouraged to talk aloud during their search, and this information, together with some probing and real time expert interpretation, enabled the experimenter to record the searching activity on a highly structured observation form. The study reveals the extent of subject searching activity, and suggests that this may have been underestimated in previous studies. The analysis of expressed topics, search formulation strategy and documents retrieved reveals the adaptive nature of the subject searching process, whereby the user adapts to the structure of the available tools. The information retrieval task in a traditional library system is tailored by the system to a single, one dimensional, sequential process. It is suggested that a major obstacle to subject searching effectiveness may lie in the lack of interaction between the different possible approaches in the searching process: the indexing language, the classification, and the titles. It is to be hoped that a future online searching environment will encourage a more truly interactive approach to subject searching.

45 citations


Journal ArticleDOI
TL;DR: The enantiomers of gossypol have been tested as male oral anti-fertility agents in hamsters and the (-) isomer was fully active at half the effective dose of the racemate, whereas the (+) isomers exerted no anti-Fertility effect.
Abstract: Summary The enantiomers of gossypol have been tested as male oral anti-fertility agents in hamsters. As determined by fertility tests the (-) isomer was fully active at half the effective dose of the racemate, whereas the (+) isomer exerted no anti-fertility effect.

Journal ArticleDOI
TL;DR: This psycholinguistic case study of a child whose linguistic output is often unintelligible or ungrammatical, and who has been diagnosed as developmental dysphasic, explores the conceptual intentions expressed in the child’s spontaneous utterances, and her linguistic mapping of these intentions.
Abstract: This is a psycholinguistic case study of a child whose linguistic output is often unintelligible or ungrammatical, and who has been diagnosed as developmental dysphasic. It explores the conceptual intentions expressed in the child’s spontaneous utterances, and her linguistic mapping of these intentions. Analysis of the scope and limits of her output reveal:

Book ChapterDOI
02 Sep 1987
TL;DR: Several of the best-known software reliability growth models are described, and examples given of their performance on real software failure data and a need for methods of comparing and evaluating software reliability forecasts is revealed.
Abstract: Computer software fails because of the presence of intellectual faults, ranging from simple coding faults to fundamental design faults. In principle, such faults can be permanently removed when they are detected by failure of the software. Then the software will exhibit reliability growth. The problem considered here is the one of forecasting this growth: it includes the estimation of the current reliability of the program from the previous failure data. We begin with a brief description of the software failure process: a non-stationary stochastic process. Several of the best-known software reliability growth models are described, and examples given of their performance on real software failure data. They shown marked disagreement and thus reveal a need for methods of comparing and evaluating software reliability forecasts. Several simple techniques for conducting this evaluation are described and illustrated using several different models on real data sets. Finally, it is shown how in certain circumstances it is possible to improve the predictive accuracy of software reliability models by a re-calibration technique.

Journal ArticleDOI
TL;DR: In this article, the convergence and optimality properties of the modified two-step algorithm for on-line determination of the optimum steady-state operating point of an industrial process were investigated.
Abstract: This paper investigates convergence and optimality properties of the modified two-step algorithm for on-line determination of the optimum steady-state operating point of an industrial process. Mild sufficient conditions are derived for the convergence and feasibility of the algorithm. It is shown that every point within the solution set of the algorithm satisfies first-order necessary conditions for optimality, and that every optimal solution belongs to this set. It is also shown that there are advantages to be gained by using a linear mathematical model of the process within the implementation of the algorithm.


Journal ArticleDOI
TL;DR: In this article, a simple intensity-independent fiber-optic temperature sensor using alexandrite crystal was constructed, which uses the change in the characteristics of the fluorescence of the material to sense the parameter required and operates using light from an electrooptically modulated He-Ne laser at 633 nm.
Abstract: In this work a simple intensity-independent fiber-optic temperature sensor using alexandrite crystal was constructed. The sensor uses the change in the characteristics of the fluorescence of the material to sense the parameter required and operates using light from an electrooptically modulated He-Ne laser at 633 nm. Microprocessor control and signal processing is used to achieve an accuracy of \sim \pm1\deg C with a 3-s response.

Journal ArticleDOI
TL;DR: The background to fibre optic means of temperature sensing and some recent developments will be reviewed in this paper.
Abstract: The subject area of fibre optic sensing is one in which there has been shown a very rapid expansion of interest over the last few years. Many novel techniques are appearing in the literature and some products are available to the industrial user. The background to fibre optic means of temperature sensing and some recent developments will be reviewed in this paper.

DOI
01 May 1987
TL;DR: In this paper, an improved algorithm is derived for obtaining and maintaining the correct optimal steady-state operation of an industrial process, inspite of deficiencies in the mathematical model employed within the optimisation procedure.
Abstract: An improved algorithm is derived for obtaining and maintaining the correct optimal steady-stateoperation of an industrial process, inspite of deficiencies in the mathematical model employed within the optimisation procedure. An augmented Lagrangian technique is employed to extend a previous method which iterates between successive solutions of parameter estimation and modified system optimisation. Optimality and convergence conditions are given, and the paper includes a detailed proof of convergence based on Zangwill's approach. The practical utility of the algorithm is demonstrated on a pilot-scale chemical vaporiser plant, where its performance is compared with previous methods.

Journal ArticleDOI
TL;DR: In this paper, a series of micro-alloyed steels has been obtained after solution treating and cooling to test temperatures in the range 750 to 1000 °C. Various holding times were given prior to testing to vary the amount of prior precipitation from 0 to 100 pct.
Abstract: The hot ductility of a series of micro-alloyed steels has been obtained after solution treating and cooling to test temperatures in the range 750 to 1000 °C. Various holding times were given prior to testing to vary the amount of prior precipitation from 0 to 100 pct. For temperatures corresponding to those giving the maximum rate of precipitation, hot ductility improved with holding time for the Nb containing steels but deteriorated for the V and Al containing steels. It is concluded that dynamic precipitation is most effective in reducing hot ductility for Nb containing steels while static precipitation impairs ductility the most for V containing steels. Whereas precipitation of NbCN and VCN readily occurred, precipitation of A1N was found to be slow and the supersaturation of Al and N had to be high to start the precipitation reaction. There was no evidence for dynamic precipitation of A1N, but static precipitation at γ grain boundaries was effective in reducing hot ductility. Although differences inR of A between samples having no and substantial precipitation prior to deformation were most marked at the temperature corresponding to that giving the maximum rate of precipitation, the temperature range over which significant differences remained could be quite marked.


Journal ArticleDOI
TL;DR: In this paper, a range of Rayleigh numbers R and Prandtl numbers σ were analyzed over a set of cavity flows, driven by horizontal thermal gradients, and a limit on the limit in which R is comparable in size to the cavity aspect ratio L → ∞ at fixed R and σ was found.
Abstract: Shallow cavity flows, driven by horizontal thermal gradients, are analysed over a range of Rayleigh numbers R and Prandtl numbers σ. Emphasis is placed on the limit in which R is comparable in size to the cavity aspect ratio L . Departures from two-dimensional steady Hadley cells, defined by the limit L → ∞ at fixed R and σ, are shown to be associated with nonlinear end effects. Eigenvalue calculations indicate the existence of a critical Prandtl number σ c , below which the core structure is not necessarily parallel with the horizontal boundaries. For σ c the parallel flow core is destroyed at Rayleigh numbers R > R c (σ). Results for the stability boundary R c (σ) are presented.

Journal ArticleDOI
TL;DR: In this article, a model is presented which predicts the relative dimensions of the pits as a function of bubble collapse pressure, the shape of the microjet and the mechanical properties of the solid.
Abstract: The collapse of cavitation bubbles generates microjets which can cause local plastic deformation on neighbouring solid materials. This deformation takes the form of pitting which will eventually lead to large-scale material erosion. A model is presented which predicts the relative dimensions of the pits as a function of bubble collapse pressure, the shape of the microjet and the mechanical properties of the solid. The high pressures required to cause material deformation are generated by a water hammer mechanism and the solid is taken to have a simple bilinear elastic-plastic response. Measurements on pits produced by both flow and spark-generated cavitation are found to lie within the bounds predicted by the model. Both the measurements and the model suggest that there is a threshold microjet velocity below which no damage occurs, although such behaviour is masked, in practice, by statistical variations.

Journal ArticleDOI
TL;DR: In this paper, a general theory of weak G-majorization for linear models is developed, which includes orderings for subsets of estimable functions, based on the idea from previous work of Giovagnoli and Wynn combined with work by Pukelsheim and Styan on the matrix concavity of information matrices.

Proceedings Article
23 Aug 1987
TL;DR: This paper considers two ways of learning by analysing past solutions that can improve future problem solving: creating macros and the chunks, and a method of learning search heuristics which complements the use of macros within a goal directed system.
Abstract: This paper is concerned with state space problem solvers that achieve generality by learning strong heuristics through experience in a particular domain. We specifically consider two ways of learning by analysing past solutions that can improve future problem solving: creating macros and the chunks. A method of learning search heuristics is specified which is related to 'chunking' but which complements the use of macros within a goal directed system. An example of the creation and combined use of macros and chunks, taken from an implemented system, is described.

Journal ArticleDOI
TL;DR: In this paper, the effects of certain bromine, phosphorus and metal compounds on polymer combustion can be interpreted in the light of the thermoanalytical behaviour of mixtures of these compounds with selected polymers.

Journal ArticleDOI
TL;DR: In this paper, the first use of GLC in 1969 to study the thermodynamics of polymer solutions has been investigated, and measurements of solubility, Henry's Law constants, activity coefficients and solubilities parameters for a number of solvents in poly(dimethyl siloxane), polyisobutylene and ethylene-propylene rubber at 25°C are given to illustrate the method.
Abstract: Since the first use of GLC in 1969 to study the thermodynamics of polymer solutions, a wide range of properties has been investigated. A brief description of the method is presented and measurements of solubility, Henry's Law constants, activity coefficients and solubility parameters for a number of solvents in poly(dimethyl siloxane), polyisobutylene and ethylene-propylene rubber at 25°C are given to illustrate the method.


Journal ArticleDOI
TL;DR: The relationship between ageing and content typologies of the literature was tested, and the median citation ages of different typologies were uneven, indicating that contentTypologies were an important factor affecting the ageing phenomena of the Literature.
Abstract: Biochemical periodical literature is investigated in the light of its ageing phenomena as reflected by the citations in Cell in 1983. The citation frequency distribution followed a negative exponential distribution for 1972-1982, with the median cita tion age of 3 years. The relationship between ageing and content typologies of the literature was tested, the median citation ages of different typologies were uneven, with the differences of nearly 7 years, indicating that content typologies were an important factor affecting the ageing phenomena of the literature.

Journal ArticleDOI
TL;DR: This paper examines briefly the state of the art of intelligent measurement on the basis of the proceedings of the IMEKO 1986 Symposium on the subject and identifies advances in computer-assisted measurement, data conditioning, measurement process control, measurement result output, and measurement data processing.

Proceedings ArticleDOI
01 Dec 1987
TL;DR: The notion of regular invariant realization of a triple (F,G;V), F,G? Rr×p, V?Rp linear space is introduced and its properties and construction is investigated as discussed by the authors.
Abstract: The notion of regular invariant realization of a triple (F,G;V), F,G ? Rr×p, V?Rp linear space is introduced and its properties and construction is investigated. This new notion of realization, allows the reduction of the study of dynamic characterisation of subspaces of singular systems to standard problems of linear systems theory.