Showing papers by "Cranfield University published in 1986"
TL;DR: Understanding of computer codes for aparticular class of problems has advanced some way toward completeness, yet the problems are sufficiently complex that naive numerical techniques can produce disaster, yet sufficiently simple that well-understood physics can be understood.
Abstract: P. L. RoeCollege of Aeronautics, Cranfield Institute of Technology,Cranfield MK43 0AL, EnglandIntroductionComputer simulations of fluid flow provide today the sort of detailedinformation concerning special cases that could previously only beobtained from experime.nts. The computer is attractive as a replacement forexperiments that are difficult, dangerous, or expensive, and as an alternativeto experiments that are impossible. Nevertheless, a computer simulationdoes not have quite the same status as a physical experiment because atpresent there usually remains some doubt about its accuracy. Even thoughthe computer code may be free of error to the extent that it operates exactlyas its author intended, it is seldom possible to give a rigorous proof thatthese intentions were in all respects correct. Most of the practical codeswritten to solve complicated problems contain empirical features, some-times in the form of "adjustable constants" whose values must be "tuned"by appeal to the experiments that the simulations are intended to displace.A computer code is described as being "robust" if it has the virtue ofgiving reliable answers to a wide range of problems without needing to beretuned. The ideal code would be one that fully met some declaredspecification of accuracy and problem range, and whose every line was anecessary contribution to that aim. Few codes yet approach that ideal; amajor impediment is that we presently have little idea what properties canbe specified without contradiction.In recent years, however, our understanding of computer codes for aparticular class of problems has advanced some way toward completeness.The problems are sufficiently complex that naive numerical techniques canproduce disaster, yet sufficiently simple that well-understood physics can3370066-4189/86/0115-0337502.00www.annualreviews.org/aronline Annual Reviews
1,777 citations
TL;DR: In this paper, a technique for extending to multidimensional flows was proposed, where the flow domain is divided into polygonal computational elements and the flow is represented by a local superposition of elementary solutions consisting of plane waves not necessarily aligned with the element boundaries.
255 citations
TL;DR: The high catalytic activity and oxygen insensitivity of this biosensor make it suitable for in vivo blood glucose monitoring in the management of diabetes and illustrate its potential usefulness for a variety of practical applications.
177 citations
TL;DR: In this paper, an analysis is made of the thermodynamic and kinetic factors affecting phase separation in blends of di-, tri-and tetrafunctional epoxy resins, cured with either diamino-diphenylsulphone (DOS) or with dicyanodiamide (Dicy), and modified with either poly(ethersulope) (PES) or carboxyl-terminated butadiene acrylonitrile (CTBN) rubber.
Abstract: An analysis is made of the thermodynamic and kinetic factors affecting phase separation in blends of di-, tri- and tetrafunctional epoxy resins, cured with either diamino-diphenylsulphone (DOS) or with dicyanodiamide (Dicy), and modified with either poly(ethersulphone) (PES) or carboxyl-terminated butadiene acrylonitrile (CTBN) rubber. The applicability and limitations of the solubility parameter approach in predicting compatibility in reactive blends are considered.
151 citations
TL;DR: In this paper, the authors studied the whole population of new firms started in St Joseph County, Indiana, between 1977 and 1982 and found that new firms played a significant role in job generation.
Abstract: The contribution of both new and small firms towards economic recovery is now universally accepted as significant. What is still unclear, however, is the extent of that contribution, particularly with regard to the new firm. Despite this, governments at all levels, federal, state and county, have designed strategies for fostering entrepreneurial activity. With little specific knowledge of the target population, these strategies have been either general in nature or based on economic theory, and, as a consequence, little is known about whether they have been effective in affecting the natural process, and in what geographic locations.
This research studied the whole population of new firms started in St. Joseph County, Indiana, between 1977 and 1982. It was concerned with both birth and death patterns, and the net jobs generated. The results confirmed the general findings of others that new firms play a significant role in job generation. Over the period, the number of jobs created by a new firm was a consistent 2.9 per cent of the total number of jobs in the industrial sectors studied. Moreover, this exceeded the 1.75 per cent of jobs lost through firms withdrawing from the labour market. Within this, activity in both firms and jobs was found to be centred in only a few SIC categories, and the results of this research suggest that simple tests of volatility and gain will help to focus strategic plans for aid on those sectors where the natural process is already generating the most new jobs.
128 citations
TL;DR: In this paper, a model for sliding friction, in which the frictional force is assumed to result from the pushing of waves of plastically deformed material in the soft surface ahead of asperities on the hard surface, is used to calculate the magnitude of the resulting plastic strain increments which progressively deform the soft surfaces.
102 citations
TL;DR: In this paper, the authors developed a structured computerized information data base for manufacturing processes, together with interactive software, which allows the designer to decide between the processes by comparing the relative costs of labour, material wastage, and tooling, followed by looking at the advantages and disadvantages of each process.
91 citations
TL;DR: In this article, the authors investigated the characteristics of 354 directors of Britain's largest companies, by analyzing the economic performance of their industrial and commercial sectors over the previous decade, directors were grouped into categories of growth, decline and turbulence.
Abstract: Summary This research investigates the characteristics of 354 directors of Britain's largest companies. Three sections of independent variables were analysed: those relating to the economic environ; those relating to the domestic environ-family background and educational experiences; those relatinig to self-concept. Directors were categorized according to the econoinic performnance of their industries-GOGOs (industries in growth); YOYOs (industries in turbulence); and DODOs (industries in decline). Several differences emerged between the characteristics of directors and the economic success of their industries for which they were strategically influential. In the past decade, researchers in the field of strategic management have attempted to isolate those factors associated with variations in economic performance. These investigations have developed from two different positions-those from a product-market standpoint, and those which start with organizational formats. Recently, however, Hambrick and Mason (1983) have argued for a third approach; an emphasis upon the values and 'moulding' of those executives who comprise the top management team. It is suggested that the characteristics of this dominant coalition may predict, partially, performance outcomes. This paper adopts the approach of Hambrick and Mason and is based upon data from 354 executive directors of Britain's largest companies, by definition the corporate leaders of the U.K. private enterprise economy. By analysing the economic performance of their industrial and commercial sectors over the previous decade, directors were grouped into categories of growth, decline and turbulence. A review of theoretical and empirical contributions from the areas of strategic management, organizational behaviour and of leadership theory, established hypotheses within three main groups: the economic environ; the domestic environ-education and family background; and those relating to the leaders' self-concept.
91 citations
TL;DR: Direct-current cyclic voltammetry is used to investigate the suitability of a ferrocene derivative as a mediator with galactose, glycolate and l-amino acid oxidases, and should be widely applicable to oxidases and other oxidoreductase enzymes.
90 citations
TL;DR: In this paper, the authors present a review aimed at assisting the designer in understanding the intricacy of this problem and the factors involved, as well as their behavior when heat is transferred across them.
76 citations
TL;DR: In this article, the authors investigated the predictive validity of the KAI over a range of product continuity/discontinuity and support the use of the Kirton Adaption-Innovation Inventory (KAI) as a marketing tool.
Abstract: The identification of consumer innovators offers marketing managers the opportunity to tailor new products to the buyers who initiate the diffusion of innovations. Progress has been made in identifying such consumers in economic and social terms, but there are advantages of cost and convenience in isolating the personality profiles of innovators, during pre‐launch product testing. However, innovative consumer’s personality traits proved elusive. Reports an investigation of innovative brand choice in the context of new food purchasing employing the Kirton Adaption‐Innovation Inventory (KAI). This test of cognitive style correlates with several personality traits associated with innovativeness; it also has high validity in the prediction of behaviour. The research investigated the predictive validity of the KAI over a range of product continuity/discontinuity. The results suggest an operational measure of product continuity/discontinuity and supports the use of the KAI as a marketing tool.
TL;DR: In this article, a heuristic is developed based on the incremental cost of increasing the lot size by one unit, which minimizes the total of production, setup, holding, shortage, and scrap costs.
Abstract: Consider a job shop which must completely fill a large make-to-order demand of a product where production yield is highly variable. After a production lot is completed, if the total output of satisfactory units is inadequate to satisfy the demand, then a new run (with associated setup cost) is made. When the output of good units exceeds the demand, then the excess units are scrapped (with possible salvage value). The optimal lot size minimizes the total of production, setup, holding, shortage, and scrap costs. A heuristic is developed based on the incremental cost of increasing the lot size by one unit. The computational ease and excellent cost performance of the heuristic favor its use in place of the mathematically optimal solution obtained by dynamic programming. Real world manufacturing applications and additional properties of the model are also discussed.
TL;DR: A nonheme-iron-containing cytochrome b557, also known as bacterioferritin, was isolated from Pseudomonas aeruginosa and found to be amorphous with a mean core size of 60-65 A.
TL;DR: In this paper, the second-order kinetics of agarose sulphate was studied and the equilibrium constant for helix growth (s) was calculated as a function of temperature from the calorimetric enthalpy change.
Abstract: Nongelling solutions of structurally regular chain segments of agarose sulphate show disorder–order and order–disorder transitions (as monitored by the temperature dependence of optical rotation) that are closely similar to the conformational changes that accompany the sol–gel and gel–sol transitions of the unsegmented polymer. The transition midpoint temperature (Tm) for formation of the ordered structure on cooling is ∼25 K lower than Tm for melting. Salt-induced conformational ordering, monitored by polarimetric stopped-flow, occurs on a millisecond time scale, and follows the dynamics expected for the process 2 coil ⇌ helix. The equilibrium constant for helix growth (s) was calculated as a function of temperature from the calorimetric enthalpy change for helix formation (ΔHcal = −3.0 ± 0.3 kJ per mole of disaccharide pairs in the ordered state), measured by differential scanning calorimetry. The temperature dependence of the nucleation rate constant (knuc), calculated from the observed second-order rate constant (kobs) by the relationship kobs = knuc(1 − 1/s) gave the following activation parameters for nucleation of the ordered structure of agarose sulphate (1 mg mL−1; 0.5M Me4NCl or KCl): ΔH* = 112 ± 5 kJ mol−1; ΔS* = 262 ± 20 J mol−1 K−1; ΔG*298 = 34 ± 6 kJ mol−1; (knuc)298 = (7.5 ± 0.5) × 106 dm3 mol−1 s−1. The endpoint of the fast relaxation process corresponds to the metastable optical rotation values observed on cooling from the fully disordered form. Subsequent slow relaxation to the true equilibrium values (i.e., coincident with those observed on heating from the fully ordered state) was monitored by conventional optical rotation measurements over several weeks and follows second-order kinetics, with rate constants of (2.25 ± 0.07) × 10−4 and (3.10 ± 0.10) × 10−4 dm3 mol−1 s−1 at 293.7 and 296.2 K, respectively. This relaxation is attributed to the sequential aggregation processes helix + helix dimer, helix + dimer trimer, etc., with depletion of isolated helix driving the much faster coil–helix equilibrium to completion. Light-scattering measurements above and below the temperature range of the conformational transitions indicate an average aggregate size of 2–3 helices.
TL;DR: In this paper, the authors investigated the relationship between aspects of organizational structure and alienation as experienced by personnel employed in nine social services organizations, and found that organizational structure was correlated with alienation.
Abstract: This study investigated the relationship between aspects of organizational structure and alienation as experienced by personnel employed in nine social services organizations. Interview schedules w...
TL;DR: The gel structures formed by naturally occurring polysaccharides, either in vivo (in, for example, plant tissue) or in vitro after extraction and purification, are normally crosslinked by extended intermolecular "junction zones" of conformationally ordered chains as discussed by the authors.
Abstract: The gel structures formed by naturally occurring polysaccharides, either in vivo (in, for example, plant tissue) or in vitro after extraction and purification, are normally crosslinked by extended intermolecular ‘junction zones’ of conformationally ordered chains. Formation and disruption of these ordered structures under biologically and industrially relevant conditions of extensive hydration may be monitored and characterised by a variety of physical techniques, in conjunction with x-ray analysis at atomic resolution in the condensed phase by fibre diffraction. Interconnecting regions of residual disorder, necessary for solubilisation of the gel network, may be introduced by structural irregularities or block character in the primary sequence.
TL;DR: In this article, the Navier-Stokes equations for plane unsteady flow are integrated numerically in order to reveal the subsequent history of events, and four principal time domains are identified, namely early, transitional, formation and ZND.
Abstract: It is assumed that energy is transferred at a rapid rate through a plane wall into a spatially uniform and initially stagnant combustible gas mixture. This action generates a shock wave, just as it does in an inert mixture, and also switches on a significant rate of chemical reaction. The Navier-Stokes equations for plane unsteady flow are integrated numerically in order to reveal the subsequent history of events. Four principal time domains are identified, namely ‘early’, ‘transitional’, ‘formation’ and ‘ZND’. The first contains a conduction-dominated explosion and formation of a shock wave; in the second interval the shock wave is responsible for the acceleration of chemical activity, which becomes intense during the ‘formation’ period. Finally a wave whose structure is in essence that of a ZND detonation wave emerges.
TL;DR: A theoretical model is proposed which is used to derive a quantitative relationship between the critical cooling rate and average crystal size at any location within a biological specimen of given shape subject to rapid freezing.
Abstract: A theoretical model is proposed which is used to derive a quantitative relationship between the critical cooling rate and average crystal size at any location within a biological specimen of given shape subject to rapid freezing. The model is applicable to the slamming, plunging or spraying methods of cryofixation provided the ice crystal size is at least 5 times greater than the size of the critical nucleus. Complete vitrification of pure water or aqueous solutions is shown to take place at cooling rates in excess of about 3 X 10(6) K/s.
TL;DR: In this paper, the effects of increasing the fin length from 250 to 375 mm on the steady-state rate of heat loss and the optimal uniform fin separation of vertical rectangular fin protruding from a horizontal or a vertical rectangular base were investigated experimentally.
TL;DR: The use of fed-batch procedures offers distinct advantages over other modes of operation of bioreactors, and is a widely researched technique.
TL;DR: This paper showed that the definitions of Rice [1] and Dugundji [3] are equivalent, which implies that the envelope of Rice is independent of the choice of a central frequency.
TL;DR: In this article, a single impact technique was used to study particle-surf ace interactions during the erosion of a typical turbine blade material, MarM002, by pyrolytic carbon particles.
TL;DR: In this paper, the Lagrangian shape functions for the quadrilateral family of finite elements were derived by linear combinations of side-interpolations and by superposition, respectively.
Abstract: This paper introduces a general theory for the derivation of the shape functions for the quadrilateral family of finite elements. The first section deals with the Lagrangian shape functions for the cases of uniform and boundary-described elements. Two basic procedures are introduced; the first by linear combinations of side-interpolations and the second by superposition. The remainder of the paper introduces a theory for the general uniform Hermitian element of any order. Details for quadrilateral elements, with first order derivatives are explained. All of the shape functions presented here were derived in the interval [0,1].
The shape functions, developed by such an engineering approach, have been used successfully in the ABSEA Finite Element System of Cranfield Institute of Technology.
TL;DR: In this paper, the authors compared the final soil profile conditions, following three deep loosening methods, i.e., deep loosenening before (A), after (B) and simultaneous with (C) surface cultivation followed by a subsequent wheeling with either high or low pressure tyres.
Abstract: This investigation compared the final soil profile conditions, following three deep loosening methods, ie deep loosening before (A), after (B) and simultaneous with (C) surface cultivation followed by a subsequent wheeling with either high or low pressure tyres Only method C combined with low pressure tyres produced a satisfactory final loose subsoil condition, emphasising the need for care in the subsequent management of deep loosened profiles To retain the deep loosening effect to benefit the next crop, one pass or bed management systems are recommended
TL;DR: In this article, the effect of three different types of defence hole systems (A, B and C) upon the stress concentration in a uniaxially loaded plate with two coaxial holes was made.
TL;DR: In this article, a critique of Von Hippel's "customer-active" paradigm of industrial innovation is presented, and the authors argue for the conceptual extension of the new paradigm.
01 Aug 1986
TL;DR: In Industry Year, the James Clayton Lecture appropriately addressed the field of manufacturing engineering and aims to contribute to a wider understanding of how our economy and standard of living critically depend on those who design, manufacture and sell the products of high quality necessary to compete in world markets as mentioned in this paper.
Abstract: In Industry Year, this James Clayton Lecture appropriately addresses the field of manufacturing engineering and aims to contribute to a wider understanding of how our economy and standard of living critically depend on those who design, manufacture and sell the products of high quality necessary to compete in world markets.The two main thrusts worldwide, in manufacturing engineering are:Automation—in particular, computer integrated, flexible manufacture to reduce overall cost and lead time and in which CADCAM, FMS and CIM are crucially important technologiesManufacture with higher precision—on which a wide range of advanced technology products are totally dependent—and in which precision engineering, micro-engineering and nanotechnology are generally less well understood and practised than by our main international competitorsThe paper traces recent developments in precision engineering in general and several new and non-conventional high precision ‘machining’ processes in particular, including those by w...
TL;DR: This paper found that consumption was positively related to the E and P dimensions, but not to the N dimension, of the Eysenck Personality Questionnaire, and suggested that the effects of N on consumption may be complex with high N scores being more attracted to alcohol by the relaxation and freedom from inhibition it provides, but also, because of their greater social anxiety, being less attracted to drinking in on-licences.
TL;DR: In this article, the erosive response is a function of surface scale thickness and temperature, with the temperature not only influencing the surface scale plasticity but also determining the contribution of the coating substrate to the impact process.