BIRD, TS 1988, 'ADMITTANCE OF RECTANGULAR WAVE-GUIDE RADIATING FROM A CONDUCTING CYLINDER', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 36, no. 9, pp. 1217-1220.
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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.
ESSELLE, K & STUCHLY, SS 1988, 'CAPACITIVE SENSORS FOR INVIVO MEASUREMENTS OF THE DIELECTRIC-PROPERTIES OF BIOLOGICAL-MATERIALS', IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, vol. 37, no. 1, pp. 101-105.
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Gowripalan, N & Cusens, AR 1988, 'Modified polymer bar reinforcement for concrete elements', Construction and Building Materials, vol. 2, no. 2, pp. 106-111.
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High strength polymer bars produced from thermoplastics were investigated with a view to using these as reinforcement, mainly for semi-structural concrete elements. This paper describes some of the properties of these bars and their possible applications. © 1987.
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, V & Waldron, K 1988, 'Force Distribution In Closed Kinematic Chains', IEEE Journal Of Robotics And Automation, vol. 4, no. 6, pp. 657-664.
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MADSEN, NK & ZIOLKOWSKI, RW 1988, 'NUMERICAL-SOLUTION OF MAXWELL EQUATIONS IN THE TIME DOMAIN USING IRREGULAR NONORTHOGONAL GRIDS', WAVE MOTION, vol. 10, no. 6, pp. 583-596.
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MOHAN, SA & RAO, SM 1988, 'TRANSIENT SCATTERING FROM A THIN ARBITRARY WIRE', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 36, no. 8, pp. 1188-1192.
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MORSE, EC & ZIOLKOWSKI, RW 1988, 'TRANSIENT MICROWAVE-HEATING OF COMPACT TOROIDAL PLASMAS', FUSION TECHNOLOGY, vol. 14, no. 3, pp. 1325-1333.
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, M, Kumar, V, Berme, N & Waldron, K 1988, 'The Dynamics Of Quadrupedal Locomotion', Journal Of Biomechanical Engineering-transactions Of The ASME, vol. 110, no. 3, pp. 230-237.
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Poulton, GT & Bird, TS 1988, 'Earth-station antennas for multiple satellite access', Journal of Electrical and Electronics Engineering, Australia, vol. 8, no. 3, pp. 168-176.
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Antenna configurations are surveyed for simultaneously accessing a number of stellites from a single earth station. Both specially designed antennas and methods for upgrading existing antennas are discussed. A general treatment is presented, although emphasis is placed on the AUSSAT system of three satellites spaced at 4°. Results indicate that in this case specially designed multiple-access antennas are possible up to the largest antenna diameters needed. However, the upgrading of existing earth stations may be limited to reflectors of <5 m in diameter, even when sophisticated feed designs are used.
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.
Thornton, BS & Langtry, T 1988, 'Prescheduling graphic displays for optimal cancer therapies to reveal possible tumour regression or stabilisation', Journal of Medical Systems, vol. 12, no. 1, pp. 31-41.
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The paper describes an adaptive control approach to the problem of the treatment of solid tumors. The evolution with time t of the state of a tumor is modelled by a two-compartment system, governed by two differential equations forming an autonomous system under therapy control u, dy1/dt = f1(y1,y2;u) dy2/dt = f2(y1,y2;u), where y1 and y2 are the number of proliferating and nonproliferating cells, respectively. The output is analyzed in the phase plane y1y2. The control problem is that of restricting the tumor state to a predetermined region of the plane by selecting a suitable change in therapy control u, e.g., modality and dosage, when the state solution intersects the boundary of this region and the ratio y1/y2 of proliferating to nonproliferating cells is displayed together with an elapsed time scale. Then, consequent selection of a suitable therapeutic sequence may be assisted by the use of a data base as part of an expert system. The process is repeated at each intersection of the prescribed boundary. Such sequences may lead to stabilization of the system through the appearance on a computer display screen of a stable equilibrium point or a limit cycle.
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, pp. 109-126.
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Ying, M 1988, 'Conjugate Transforms For Tau-T,L-Semigroups Of Distance Distribution-Functions', Kexue Tongbao, vol. 33, no. 23, pp. 2001-2002.
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Ying, M 1988, 'On Standard Models Of Fuzzy Modal-Logics', Fuzzy Sets and Systems, vol. 26, no. 3, pp. 357-363.
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Ying, M 1988, 'Report from Jiangxi Province, People's Republic of China', Fuzzy Sets and Systems, vol. 25, no. 3, p. 382.
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Ying, M 1988, 'Some Notes On Multidimensional Fuzzy-Reasoning', Cybernetics And Systems, vol. 19, no. 4, pp. 281-293.
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ZIOLKOWSKI, RW, MARSLAND, DP, LIBELO, LF & PISANE, GE 1988, 'SCATTERING FROM AN OPEN SPHERICAL-SHELL HAVING A CIRCULAR APERTURE AND ENCLOSING A CONCENTRIC DIELECTRIC SPHERE', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 36, no. 7, pp. 985-999.
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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 1988, '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.
Bird, TS 1988, 'Reflections in open-ended elliptical waveguide with an infinite flange', IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), pp. 1226-1229.
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Experience with smooth-wall horn radiators of rectangular and circular cross-section has shown that significant reflection can occur from apertures of moderate size, resulting in mismatch at the horn input. The existing literature gives no indication of the level of reflection in open-ended elliptical waveguide, although W. C. Chew et al. (1986) recently formulated the problem. The purpose of this study is to outline another solution to the problem and to present preliminary theoretical results. To demonstrate the effect of the open end, the computed reflection coefficient of the TEc11 mode is plotted as a function of normalized frequency ka with waveguide ellipticity as a parameter. In these calculations, coupling to other modes in the aperture was neglected, an approximation known to work well provided the high-order modes are below cutoff. Reflection in elliptical waveguide increases as a/b increases in much the same way as reflection of the TE10 mode in rectangular waveguide. Well above cutoff, the level reflection of the TEc11 mode was found to be approximately the same as for the TE10 mode in open-ended rectangular waveguide with the same value of a/b.
Dissanayake, MWMG & Poo, AN 1988, 'Robot trajectory planning for minimising residual vibrations', pp. 471-474.
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An investigation into the effect of the trajectory shape on resulting arm vibrations is presented based on the concept of the shock spectrum. A method to obtain trajectories whose shock spectrum has prescribed properties is briefly described, and some preliminary results are presented. A comparison of various trajectory planning algorithms, in terms of their effectiveness in reducing residual vibrations and the move time, is given. Two performance indices are defined to quantify the information obtained through the shock spectrum and the move time analysis. The superiority of a trajectory based on the simultaneous minimization of the time of travel and residual response is illustrated.
Gale, DJ & Braun, RM 1988, '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.
Gardner, JF, Srinivasan, K & Waldron, KJ 1988, 'New method for controlling forces in redundantly actuated closed kinematic chains', American Society of Mechanical Engineers, Dynamic Systems and Control Division (Publication) DSC, pp. 315-324.
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Proper control of robotic systems which incorporate closed kinematic chains is important in many applications. Among these are the multi-robot work cell and legged vehicles. In these applications the inverse problem is under-specified and hence no unique solution exists for the force distribution corresponding to a specified trajectory. A framework within which additional constraint equations may be written is presented here, and the force distribution solved in closed form for a walking machine application. These constraints are related to system performance goals of interest, such as improved traction and/or load sharing among the legs. The proposed technique is shown to be computationally simpler than other alternative solutions to the same problem.
Huang, MZ & Waldron, KJ 1988, 'Efficient rate allocation algorithm in redundant kinematic chains', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 457-464.
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This paper addresses a basic problem which arises in the coordination of serial chain manipulators, namely, that of decomposing a given end effector velocity state into a set of joint rates. Such a problem is indeterminate for manipulators with kinematic redundancy. A novel method of solving the rate distribution problem for the class of fully revolute-jointed, serial manipulators is developed. The technique is an extension of the axial field solution scheme developed initially for solving the force allocation problem in a statically indeterminate parallel chain system. The basis of the solution method lies in the dualities of velocity and force systems between series and parallel mechanisms. The method offers an efficient means of rate coordination and is especially useful in the control of manipulators with high degrees of redundancy. Two examples have been given for illustration.
Kumar, V & Waldron, KJ 1988, '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 1988, '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.
Sabada, S, Srinivasan, U, Kinzel, GL & Waldron, KJ 1988, 'Automatic synthesis of four-bar mechanisms for four-position motion generation', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 121-128.
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The synthesis of four bar mechanisms designed to go through four precision positions based on optimization theory and rectified synthesis are discussed. The techniques for automatic synthesis presented have been implemented in the interactive synthesis package RECSYN.
Srinivasan, U, Sabada, S, Kinzel, GL & Waldron, KJ 1988, 'Automatic synthesis of four-bar mechanisms for two- and three-position motion generation', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 113-120.
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A method is presented for the automatic synthesis of four bar mechanisms based on optimization theory. The procedure applies to designs for rigid-body guidance for two and three finitely separated positions of the coupler when the mechanism is driven at one of the cranks. The technique presented here incorporates rectification developed by K.J. Waldron (1975, 1977) and K.J. Waldron and R.T. Strong (1978a, 1978b, 1979), to eliminate branch and order problems and is implemented in the interactive synthesis package RECSYN (J.C. Chuang, Strong and Waldron, 1981).
Vasilakos, A & Koubias, S 1988, 'Distributed learning algorithms for data network routing problem: models and convergence analysis', pp. 544-547.
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The authors develop a theoretical basis for analyzing data communication networks in which the routing strategy is determined by learning automata. A mathematically tractable abstract representation of the network and the equilibrium behavior of the automata at the nodes is given. In particular, distance-diminishing operators are used to study the behavior of the state of an automaton acting in a nonstationary environment.
Vasilakos, AV 1988, 'Distributed learning algorithms for data network routing problem: Models, convergence analysis and optimality', pp. 218-221.
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The behavior of the automata at the nodes of a data network is studied for an abstract network representation in which only very general functional properties are assumed. A model of a nonstationary environment is proposed with state variables as penalty parameters. The limiting behavior of the model is studied. Simulation results show that under abnormal conditions (i.e., change of topology) the learning algorithms outperformed existing routing algorithms. Using a minimal amount of feedback, the equalizing properties of automata in equilibrium can still be used to produce optimal or nearly optimal routing.
Vasilakos, AV & Koubias, SA 1988, 'On routing and performance comparison of techniques for packet-switched networks using learning automata', Proceedings - IEEE International Symposium on Circuits and Systems, pp. 109-113.
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Distributed adaptive routing algorithms with the ability to adaptively proportion traffic over several paths is proposed for packet-switched data networks. A learning automaton is situated at each node of the network where a routing decision must be made that directs traffic entering the node onto one of the outgoing links. Using network feedback, an automaton modifies its routing strategy to improve its link selections. This approach has the advantage over existing routing schemes of offering a simple and extremely practical feedback and updating policy.
Waldron, MB & Waldron, KJ 1988, 'Conceptual CAD tools for mechanical designers', pp. 203-209.
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In this paper we have identified aspects important to the mechanical designer at the conceptual design stage. The creation of successful CAD design tools must take these into account. These are the functionality, optimization and the language of design. The cognitive studies which support this assertion are presented.
Ying, M 1988, 'On zadeh's method for interpreting linguistically quantified proposition.', Proceedings of The International Symposium on Multiple-Valued Logic, 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.
Ziolkowski, RW 1988, 'New electromagnetic directed energy pulses', Proceedings of SPIE - The International Society for Optical Engineering, pp. 312-319.
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© 1988 SPIE. All rights reserved. New electromagnetic directed energy pulse train (EDEPT) solutions of Maxwell’s equations have been obtained. One particular solution, the modified power spectrum (MPS) prdse, will be described in detail. This pulse can be tailored to give directed energy transfer in space in such a manner that theoretically it beats the diffraction limit. These EDEPT solutions are not physically pathological and can be reconstructed from causal Green’s functions. They represent fields that recover their initial ampfitudes along the direction of propagation out to extremely large distances from their initial location. Moreover, these fields appear to be launchable from finite aperture antennas.