Collins, GA, Durance, G, Hogg, GR, Tendys, J & Watterson, PA 1988, 'Small aspect ratio tokamak configurations generated by rotating magnetic field current drive', Nuclear Fusion, vol. 28, no. 2, pp. 255-266.
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Small aspect ratio tokamak configurations are produced by adding a toroidal magnetic field to the rotamak. Configurations with toroidal fields ranging up to 200 G at the magnetic axis are studied. Typical parameters are Itor 2 kA, Bpoi 50 G, q0 1-3, ne (peak) 1019 m-3Te 12 eV, τp 15 μs and τe 5μs for an RF input power of 40 kW. Most features of these configurations can be modelled by an MHD equilibrium code. The presence of the toroidal field is observed to have a significant influence on the rotating magnetic field current drive mechanism. © 1988 IOP Publishing Ltd.
Hadgraft, RG & Daniell, TM 1988, 'Computers in hydrology - past, present and future', Civil engineering transactions, vol. CE30, no. 4, pp. 207-223.
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Hydrology has developed as a numerically intensive branch of science/engineering. The developments in hardware over the last 30 years, and the parallel developments in computer software are discussed. The effects of this computer revolution on the development of software and modelling in hydrology are examined. This paper also reviews some of the hardware and software issues that are important when developing new software. Some implications for engineering education in computing are discussed. The issues that are relevant today, and a guess at those that might emerge in the future in the use of computers in hydrology are considered.
Kumar, VR & Waldron, KJ 1988, 'Force distribution in closed kinematic chains', IEEE Journal on Robotics and Automation, vol. 4, no. 6, pp. 657-664.
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OWENS, DR, VOLUND, A, JONES, D, SHANNON, AG, JONES, IR, BIRTWELL, AJ, LUZIO, S, WILLIAMS, S, DOLBEN, J, CREAGH, FN & PETERS, JR 1988, 'RETINOPATHY IN NEWLY PRESENTING NON-INSULIN-DEPENDENT (TYPE-2) DIABETIC-PATIENTS', DIABETES RESEARCH CLINICAL AND EXPERIMENTAL, vol. 9, no. 2, pp. 59-65.
Pandy, MG, Kumar, V, Berme, N & Waldron, KJ 1988, 'The Dynamics of Quadrupedal Locomotion', Journal of Biomechanical Engineering, vol. 110, no. 3, pp. 230-237.
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This paper presents a dynamical analysis of quadrupedal locomotion, with specific reference to an adult Nubian goat. Measurements of ground reaction forces and limb motion are used to assess variations in intersegmental forces, joint moments, and instantaneous power for three discernible gaits: walking, running, and jumping. In each case, inertial effects of the torso are shown to dominate to the extent that lower-extremity contributions may be considered negligible. Footforces generated by the forelimbs exceed those exerted by the hindlimbs; and, in general, ground reactions increase with speed. The shoulder and hip dominate mechanical energy production during walking, while the knee plays a more significant role in running. In both cases, however, the elbow absorbs energy, and by so doing functions primarily as a damping (control) element. As opposed to either walking or running, jumping requires total horizontal retardation of the body’s center of mass. In this instance, generating the necessary vertical thrust amounts to energy absorption at all joints of the lower extremities.
Sananikone, V & Ball, JE 1988, 'A water management model to assess available water resources in a multi reservoir system.'.
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The capability and potential uses of a water management model suitable for multi reservoir water resource investigations, is described. Using historical rainfall data, the expected irrigation demand, and the catchment and reservoir characteristics, the model described produces the monthly storage behaviour, overflows and water levels in the reservoir system. An application of this model to the proposed Norwest development is also presented.
Sananikone, V & Ball, JE 1988, 'A water management model to assess available water resources in a multi reservoir system.'.
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The capability and potential uses of a water management model suitable for multi reservoir water resource investigations, is described. Using historical rainfall data, the expected irrigation demand, and the catchment and reservoir characteristics, the model described produces the monthly storage behaviour, overflows and water levels in the reservoir system. An application of this model to the proposed Norwest development is also presented.
Stewart, MG & Melchers, RE 1988, 'Simulation of human error in a design loading task', Structural Safety, vol. 5, no. 4, pp. 285-297.
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Given that human error, particularly in design, causes a significant proportion of structural failures, it is of interest to develop a design task model that simulates the effect of human error in design. The development and analysis of a model for a typical design task (loading calculations for sizing a steel portal frame building) are described in the present paper. It is shown that human error in design loading calculations leads to a loss of structural safety. A comparison of the results of the design task model with available survey data for the same task suggests that such models can realistically represent the effect of human error on the modelled process. © 1988.
Vigneswaran, S & Kiat, WY 1988, 'Detailed investigation of effects of operating parameters of ultrafiltration using laboratory-scale ultrafiltration unit', Desalination, vol. 70, no. 1-3, pp. 299-316.
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Cross flow ultrafiltration is a pressure driven membrane process in which the fluid to be filtered flows parallel to the membrane surface. The formation of filter cake can be reduced by scouring force of the flow, thus better permeate rate is obtained. Laboratory-scale ultrafiltration experiments with Polyvinyl Alcohol (PVA) solution of known molecular weight was carried out to study the membrane filter performances with respect to operating parameters. These operating parameters included, membrane molecular weight cut off size, molecular weight of PVA, influent concentration, cross flow velocity and applied pressure. It was discovered that clogging in the membrane occurs quite slowly during first 30 minutes, and quasi-steady state was noticed normally after 50 minutes of filtration time. In this study, steady state flux data were used to develop semi-empirical and empirical correlations which are useful in the optimum design of ultrafiltration. © 1988.
Vigneswaran, S & Pandey, JR 1988, 'ASSESSING THE SUITABILITY OF MEMBRANES FOR MICROFILTRATION - AN EMPIRICAL APPROACH.', Filtration and Separation, vol. 25, no. 4, pp. 253-255.
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Very little work has been done on the performance of cross-flow microfiltration during the filter run. The authors suggest an empirical methodology to characterize membrane performances by using standard curves. A procedure is developed to establish standard curves for cross-flow microfiltration. The standard curve arrived at gives a reasonable prediction for the performance of CMF, but a larger number of data have to be analyzed with respect to the standard curve obtained before it can be used for practical purposes.
Vigneswaran, S & Tien, C 1988, 'EMPIRICAL CORRELATION FOR ESTIMATING PRESSURE DROP ACROSS CLOGGED FILTERS.', Aqua (Oxford), no. 3, pp. 110-115.
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Empirical correlations for estimating pressure drop in clogged filters were established. The correlations are based on pressure drop data collected from filtration of kaolin clay suspensions under different operating conditions. A simple procedure for applying the correlations is outlined.
Vigneswaran, S & Tulachan, RK 1988, 'Mathematical modelling of transient behaviour of deep bed filtration', Water Research, vol. 22, no. 9, pp. 1093-1100.
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This study proposes a mathematical model based on the concept that there exists a maximum limit on particle deposition on the filter grain, to describe the entire cycle of filtration. The three model coefficients appearing in this mathematical model were calculated for different operating conditions using experimental results obtained from a filter 2 cm in depth. Although these model coefficients were different for different operating conditions, a uniform trend was observed in the variation of model parameters with operating conditions. © 1988.
Waldron, MB & Waldron, KJ 1988, 'A time sequence study of a complex mechanical system design', Design Studies, vol. 9, no. 2, pp. 95-106.
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In the present work the design of a complex mechanical system, namely the leg of a walking machine, is investigated by using a time analysis that uses specially coded boxes to identify the use of important knowledge bases and the decisions made. Based on this study, hypotheses on the generation of sub-goals and the length of the conceptual design process are proposed for future research wotk in mechanical design theory and methods. © 1988.
Watterson, PA 1988, 'Analytical solutions for the current driven by a rotating magnetic field in a cylindrical plasma with azimuthal field', Journal of Plasma Physics, vol. 40, no. 1, pp. 109-126.
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The generation of steady currents by a rotating magnetic field (RMF) in a cylindrical plasma permeated by a steady azimuthal (or toroidal) magnetic field is studied analytically. Solutions are presented for the following limiting cases:(1) high resistivity, when the penetration of the RMF and current drive are confined to a skin depth layer;(2) low resistivity and weak toroidal field (small compared with the RMF), when the RMF fully penetrates the plasma and the toroidal current is that due to nearly synchronous rotation of the electron fluid with the RMF;(3) low resistivity and intermediate toroidal field (comparable to the axial field associated with synchronous current), when the toroidal current is a significant fraction of its synchronous value, but large oscillating fields are generated; and(4) strong toroidal field, when the RMF fully penetrates the plasma but current is only driven in a boundary layer at the plasma edge.The applicability of these solutions is governed by the relative sizes of three dimensionless parameters.
Zuofa, K, Loganathan, P & Isirimah, NO 1988, 'Effects of crude oil applications to soil on the growth and yield of maize, okro and cassava in Nigeria', Oil and Chemical Pollution, vol. 4, no. 4, pp. 249-259.
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The effects of different doses (0, 1, 2, 4 and 8 litres/m2) of crude oil applications to soil on the growth and yield of maize, okro and cassava as well as on soil properties were investigated in two field experiments with mixed croppings (maize/okro and maize/cassava) in an acidic sandy loam soil at Port Harcourt, Nigeria. Crude oil applications above 2 litres/m2 significantly affected crop germination, plant height and yield of maize and okro but not of cassava. Weed population in all the plots decreased significantly with increase in oil doses. Oil application slightly increased organic matter content, pHand total nitrogen content in the soils. © 1988 Elsevier Science Publishers Ltd, England.
Agrawal, SK & Waldron, KJ 1970, 'Impulsive model for a quadruped running machine', American Society of Mechanical Engineers, Dynamic Systems and Control Division (Publication) DSC, pp. 139-148.
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A model for a quadruped running machine is proposed in which controlled longitudinal and vertical impulses are delivered to the legs during support phase. A steady description of the machine is when the states at the beginning of successive cycles are invariant except for a prespecified traverse in the longitudinal direction. A graphical method is outlined to obtain steady solutions for quadruped gaits. Some representative examples of gaits are solved for the possible infinity of solutions in which a pair of feet hit the ground in unison such as the pace, bound and trot.
Gale, DJ & Braun, RM 1970, 'Path length analyzer for digital microwave radio', pp. 140-143.
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An instrument is proposed that would use the tellurometer technique of T.L. Wadley (1958) to analyze the electrical length as opposed to the physical length of a microwave radio's propagation path. The instrument can be used by the line-of-sight radio-link engineer to assess such factors as stable and turbulent atmospheric multipath, reflections from elevated ground layers, reflections from atmospheric sheets, reflections from ground or water, reflections due to inverse bending and ducting. The full extent of the usefulness of the instrument has not yet been investigated. A practical example of the analysis of the ground reflection is given. Time-domain analysis is suggested for analyzing paths under test.
Kumar, V & Waldron, KJ 1970, 'FORCE DISTRIBUTION IN CLOSED KINEMATIC CHAINS.', pp. 114-119.
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The problem of force distribution in systems involving multiple frictional contacts between actively coordinated mechanisms and passive objects is examined. The special case in which the contact interaction can be modeled by three components of forces (zero moments) is particulary interesting. The Moore-Penrose generalized inverse solution for such a model (point contact) is shown to yield a solution vector such that the difference between the forces at any two contact points projected along the line joining the two points vanishes. Such a system of forces is described by a helicoidal vector field which geometrically similar to the velocity field in a rigid body twisting about an instantaneous screw axis. A method to determine this force system is presented. The possibility of superposing another force field which constitutes the null system is investigated.
Kumar, VR & Waldron, KJ 1970, 'Force distribution in walking vehicles', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 473-480.
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This paper addresses the problem of the appropriate distribution of forces between the legs of a legged locomotion system for walking on uneven terrain. The legs of the walking machine and the terrain form closed kinematic chains. The system is statically indeterminate and an optimal solution is desired for force control of the legs. In addition, as unisense force limitations are imposed on the wrenches acting at the feet, it is important to be able to determine for any given configuration whether or not a set of valid contact forces can be found which will ensure the stability of the vehicle. Fast and efficient algorithms to solve these problems have been developed. The trade-off between computational simplicity and optimality makes it necessary to resort to suboptimal algorithms. In particular, schemes based on the Moore Penrose Generalized Inverse or the pseudo inverse, and linear programming were investigated. An active compliance control scheme with varying leg compliances is a suitable paradigm for control. A variation of the linear programming technique that is well-suited to the problem of predicting instability in the vehicle is also presented.
Ying, M 1970, 'On Zadeh's method for interpreting linguistically quantified proposition', [1988] Proceedings. The Eighteenth International Symposium on Multiple-Valued Logic, Proceedings. The Eighteenth International Symposium on Multiple-Valued Logic, IEEE, pp. 248-252.
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The author establishes an interesting result on multiquantified propositions. He then gives a novel method for interpreting linguistically quantified propositions with nearness measures.
Zowghi, D 1970, 'An Experimental Expert System for DNA Restriction Mapping', Proceedings of the International Conference on Expert Systems and Applications, Avignon, France.
