Aubrey, T & White, P 1992, 'Simple numerical integration of logarithmic singularities in moment method solutions of electromagnetic problems', Electronics Letters, vol. 28, no. 16, pp. 1519-1519.
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Moment method solutions to electromagnetic problems can require the integration of functions containing logarithmic singularities. A simple technique for the numerical integration of these singularities is presented. The technique is applied in the calculation of the self-impedance of a surface dipole. The convergence of the solution using this method is compared to the convergence of existing methods. © 1992, The Institution of Electrical Engineers. All rights reserved.
Avenel, O, Xia, JS, Andraka, B, Jee, CS, Xu, M-F, Qian, YJ, Lang, T, Moyland, PL, Ni, W, Signore, PJC, Adams, ED, Ihas, GG, Meisel, MW, Stewart, GR, Sullivan, NS & Takano, Y 1992, 'Magnetic measurements ofCeAl3to below 1 mK', Physical Review B, vol. 45, no. 10, pp. 5695-5698.
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Avenel, O, Xu, J, Xia, JS, Xu, M-F, Andraka, B, Lang, T, Moyland, PL, Ni, W, Signore, PJC, van Woerkens, CMCM, Adams, ED, Ihas, GG, Meisel, MW, Nagler, SE, Sullivan, NS, Takano, Y, Talham, DR, Goto, T & Fujiwara, N 1992, 'Low-temperature magnetic measurements of anS=1 linear-chain Heisenberg antiferromagnet', Physical Review B, vol. 46, no. 13, pp. 8655-8658.
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Baweja, D, Munn, RL, Roper, H & Sirivivatnanon, V 1992, 'Situ assessments of long-term performance of plain and blended cement concretes', Transactions of the Institution of Engineers, Australia. Civil engineering, vol. CE34, no. 2, pp. 115-127.
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Between 1987 and 1990, selected elements from ten individual structures from within four facilities were examined to assess the long-term performance of concretes used. Structural members examined encompassed slabs on grade, suspended slabs and wharf elements. Individual concretes forming the selected structures had binders of normal portland cement, portland cement with fly ash or ternary systems of fly ash, ground granulated blast furnace slag and portland cement. Slag aggregates were used in certain of the concretes. Interest focused on the long-term in-service durability of the concretes. Conclusions were drawn with respect to the performance of the concretes.
Briscoe, BJ, Thomas, PS & Williams, DR 1992, 'Microscopic origins of the interface friction of organic films: The potential of vibrational spectroscopy', Wear, vol. 153, no. 1, pp. 263-275.
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CAO, HT & SIRIVIVATNANON, V 1992, 'CORROSION OF STEEL IN CONCRETE WITH AND WITHOUT SILICA FUME - REPLY', CEMENT AND CONCRETE RESEARCH, vol. 22, no. 1, pp. 188-189.
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DHARMAPPA, H, VERINK, J, FUJIWARA, O & VIGNESWARAN, S 1992, 'Optimization of granular bed filtration treating polydispersed suspension', Water Research, vol. 26, no. 10, pp. 1307-1318.
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The need for economic optimization of a filter unit leading to its least cost design with respect to filtration velocity, run time, depth and medium size has long been identified but there are no algorithms towards this end. In this study, an algorithm incorporating a NLP (non-linear programming) software (NPSOLâSystem Optimization Laboratory, Stanford University, Calif.) and response surface methodology (RSM) is presented for optimal design and operation of a filter unit. Also, the simulation model included in the optimization takes into account the polydispersity of the influent. The optimization results obtained using laboratory data have shown that the filter design and operating parameters are highly dependent on the particle size distribution (PSD) of the influent. The cost of the filter unit with influent having the same total particles mass concentration and turbidity but with greater fraction of fine particles was about 46% higher. This demonstrates the importance of incorporating PSD instead of suspended solids (SS), turbidity units (TU) or volume average diameter in the design and operation of filter units. The proposed approach, however, is applicable only for single medium filters. Further research is warranted to extend it to dual and tri media filters.
Dharmappa, HB, Verink, J, Ben Aim, R, Yamamoto, K & Vigneswaran, S 1992, 'A comprehensive model for cross-flow filtration incorporating polydispersity of the influent', Journal of Membrane Science, vol. 65, no. 1-2, pp. 173-185.
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A semi-empirical model is presented for the prediction of foulant deposit thickness and concentration, and thereby, predicting the permeate flux in cross-flow microfiltration and ultrafiltration. The scope of the model is limited to colloidal suspensions (i.e. non-diffusive solutes) and its hallmark is its applicability to polydispersed influents. The theoretical model was verified with experimental observations and found to yield a fairly good agreement with an error less than 62% of the average flux over 100 min of filtration. However, evaluation of model coefficients a and b is necessary through laboratory studies. The model was successfully used to predict the effect of particle size distribution (PSD) on permeate flux. The simulation results corroborate the contention that the long-term flux decline is due to the reduction is foulant deposit permeability via infiltration of fines into the cake, thereby demonstrating the importance of influent particle size distribution (PSD) on foulant deposit permeability. The proposed model is a first step towards the modeling of polydispersed influents. As such there is a lot of scope for further refinements which is briefly discussed.
Dr. Pocock, NA, Sambrook, PN, Nguyen, T, Kelly, P, Freund, J & Eisman, JA 1992, 'Assessment of spinal and femoral bone density by Dual X-Ray absorptiometry: Comparison of lunar and hologic instruments', Journal of Bone and Mineral Research, vol. 7, no. 9, pp. 1081-1084.
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Abstract Clinical application of techniques for assessing bone mineral density (BMD) requires accurate and precise measurements that can be related to clearly defined normal ranges. In this study we investigated the clinical interpretation of BMD values in a group of individuals measured on the same day with two different dual-energy x-ray densitometers (Lunar DPX and Hologic QDR 1000). The BMD results were analyzed as absolute values in g/cm2 and with respect to young and age-specific normals as defined by each manufacturer. Absolute BMD values measured by the two instruments were highly correlated (lumbar spine r = 0.98, femoral neck r = 0.95; p < 0.0001). In the lumbar spine, the two instruments assigned almost identical values when expressed as a percentage of age-matched values and as a percentage of young normals, despite a small but systematic difference between the values assigned for the latter index. In the femoral neck, however, there were significant differences in assignments between instruments, expressed both as a percentage of young normal (mean difference 6.2%) and with respect to age-matched values (mean difference 3.3%). In particular, in premenopausal subjects femoral neck values with the Hologic instrument were assigned significantly lower values. This study shows effective comnparability between these two instruments for absolute and relative values for the lumbar spine, as well as for absolute values at the femoral neck, but important differences for normality assignments at the femoral neck. These latter differences may produce bias in the “diagnosis” of femoral neck osteoporosis and may have important implications for clinical decision making. Until these differences are resolved, clinicians should not rely solely on femoral neck BMD measurements in clinical decision making.
Guo, YJ & Barton, SK 1992, 'A high-efficiency quarter-wave zone plate reflector', IEEE Microwave and Guided Wave Letters, vol. 2, no. 12, pp. 470-471.
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A multilayered quarter-wave zone plate reflector antenna operating in the microwave range is presented. The theory for designing the reflector and experimental results are given. An efficiency of 55% was obtained with a prototype reflector antenna. © 1992 IEEE
HADGRAFT, R & WIGAN, M 1992, 'On-the-job Training for Engineers Using Hypertext', European Journal of Engineering Education, vol. 17, no. 2, pp. 159-165.
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There is a pressing need for more efficient methods of delivering updated engineering information, especially in the workplace. Hypertext offers the author the ability to structure information in ways which are more flexible than conventional print media. The intention of presenting training material using hypertext is to develop an explorative attitude in the reader. The reader is encouraged to follow his/her own path through the material, with the option of following some topics to a greater depth than would normally be expected. Hypertext also provides a tightly integrated package of information, guidance, and often also the ability to execute programs or procedures described in the document. It can also provide concise support for experts as well as assistance—in the same document. This paper (i) outlines the concepts and facilities in typical hypertext implementations, (ii) describes the reactions that have been obtained in the use of an on-line code of practice (Australian Rainfall and Runoff), and (iii) offers some guidelines for structuring engineering documents for hypertext. © 1992, Taylor & Francis Group, LLC. All rights reserved.
HADGRAFT, RG 1992, 'Experiences of Two Problem-oriented Courses in Civil Engineering', European Journal of Engineering Education, vol. 17, no. 4, pp. 345-353.
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Current engineering courses are not structured to develop real problem-solving skills in their students. They rely on a bottom-up approach to learning, where the first three years is spend mostly on theory, with almost no practice at problem definition. Instead, the students spend most of their time solving carefully designed exercises. Real-world problems are not as neatly packaged as these exercises, and, as a consequence, graduate engineers often lack the problem-definition and problem-recognition skills that are essential if the theory they have learned is to be useful to them. On the contrary, a problem-oriented course requires the students to develop those problem recognition skills. It also is intended to develop student-directed learning, and group and communication skills. A problem-oriented approach was used in 1991 in two second-year courses in civil engineering—surveying and computing. The courses were well received by the students, and the average exam result for surveying showed a noticeable improvement, while the average exam result for computing showed a marginal improvement. (There were, however, other encouraging signs in the computing course. The author believes that the difference in response between the two subjects is due to the difference between working in groups and working individually, and a course change for the computing subject for 1992 is proposed. © 1992, Taylor & Francis Group, LLC. All rights reserved.
Indraratna, B & Nutalaya, P 1992, 'Reinforcement of planar discontinuities in elastic rock', Geotechnical and Geological Engineering, vol. 10, no. 2, pp. 135-140.
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Indraratna, B, Balasubramaniam, AS & Balachandran, S 1992, 'Performance of Test Embankment Constructed to Failure on Soft Marine Clay', Journal of Geotechnical Engineering, vol. 118, no. 1, pp. 12-33.
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Indraratna, B, Balasubramaniam, AS, Phamvan, P & Wong, YK 1992, 'Development of negative skin friction on driven piles in soft Bangkok clay', Canadian Geotechnical Journal, vol. 29, no. 3, pp. 393-404.
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This paper describes the results of short-term pullout tests and long-term full-scale measurements of negative skin friction on driven piles in Bangkok subsoils. Two instrumented cylindrical (hollow) prestressed concrete piles were fully equipped with two independent load-measurement systems, load cells, and telltale rods. Pore pressures and ground movements in the vicinity of the piles were monitored throughout the period of investigation. The effect of bitumen coating on negative skin friction was also studied. The long-term behaviour of driven piles was compared with the estimated values obtained from short-term pullout tests and soil strength data. It was found that the negative skin friction can be predicted well by the effective stress approach using values of β between 0.1 and 0.2. The load–settlement and load–transfer behaviour were numerically modelled to acquire a more comprehensive understanding of negative skin friction developed on driven piles. A settlement-controlled concept is also introduced for piles subjected to negative skin friction, on the basis of these findings. Key words : consolidation, downdrag, driven pile, embankment, finite elements, pore pressures, pullout, settlements, soft clay.
James, M & Hoang, D 1992, 'Design of low-cost, real-time simulation systems for large neural networks', Journal of Parallel and Distributed Computing, vol. 14, no. 3, pp. 221-235.
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Systems with large amounts of computing power and storage are required to simulate very large neural networks capable of tackling complex control problems and real-time emulation of the human sensory, language, and reasoning systems. General-purpose parallel computers do not have communications, processor, and memory architectures optimized for neural computation and so cannot perform such simulations at reasonable cost. This paper analyzes several software and hardware strategies to make feasible the simulation of large neural networks in real-time and presents a particular multicomputer design able to implement these strategies. An important design goal is that the system must not sacrifice computational flexibility for speed as new information about the workings of the brain and new artificial neural network architectures and learning algorithms are continually emerging. © 1992.
LEYDEKKERS, P & TEUNISSEN, B 1992, 'SYNCHRONIZATION OF MULTIMEDIA DATA STREAMS IN OPEN DISTRIBUTED ENVIRONMENTS', LECTURE NOTES IN COMPUTER SCIENCE, vol. 614, pp. 94-104.
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This paper presents a study of synchronization mechanisms for real-time video, audio and text data streams. Synchronization is an important and complex issue when multimedia information, stored at geographically distributed locations, has to be transport
LOGANATHAN, P, HEDLEY, MJ & CLARK, SA 1992, 'THE MANUFACTURE AND EVALUATION OF GRANULAR POTASSIUM-CHLORIDE FERTILIZERS', FERTILIZER RESEARCH, vol. 31, no. 3, pp. 291-304.
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A finely divided red potassium chloride (KCl) (particle size distribution: 79% <0.5 mm, 20% 1-0.5 mm and 1% 1-2 mm) was granulated by adding eight readily available and relatively inexpensive binders using a rotating drum in the laboratory. The binders used were: urea, pulp and paper waste liquor containing lignosulphonate, urea + pulp and paper waste liquor, Borrebond powder (a commercial product containing lignosulphonate), urea + formaldehyde, ammonium sulphate, ammonium sulphate + pulp and paper waste liquor and a waste liquor containing ammonium sulphate from a Ferritin production plant. Of these, except for urea and urea + pulp and paper waste liquor which produced KCl granules having low critical relative humidity at 30°C (CRH) (<55%) and Borrebond which produced KCl granules of low crushing strength (1.1 kg for 2-3 mm granules) the other five binders produced granules with good size distributions, high crushing strengths (2.0-2.5 kg for 2-3 mm granules), CRH (65-70%) and suitable nutrient contents (K, 46-50%, Cl, 42-47%). These values are very close to those of the standard chipped KCl (crushing strength, 2.5 kg; CRH, 65-70%; K, 50%; Cl, 47%). Crushed chipped KCl (74% <1 mm, 25% 1-2 mm, 1% 2-3 mm) when cogranulated in the pilot plant with the 5 binders found successful in the laboratory, produced granules having similar characteristics as the corresponding ones produced in the laboratory. Granules produced both in the laboratory and the pilot plant had lower abrasion resistance (higher % degradation) than chipped KCl. The abrasion resistance however markedly increased when the fines (<1.4 mm) in the granules were removed. Glasshouse trials using barley as test crop demonstrated that the agronomic values of the KCl prototype granules produced with the 5 binders were similar to chipped KCl and granules produced from the feedstock KCl and water. © 1992 Kluwer Academic Publishers.
LOGANATHAN, P, HEDLEY, MJ, CLARK, SA & BOLAN, NS 1992, 'GRANULATION OF FINELY CRYSTALLINE AMMONIUM-SULFATE USING CALCIUM-OXIDE AND SULFURIC-ACID', FERTILIZER RESEARCH, vol. 31, no. 1, pp. 85-93.
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Two types of finely crystalline ammonium sulphate (particle size distributions: white type 7% 2-3 mm, 45% 1-2 mm, 48% <1 mm; blue type 1% 2-3 mm, 8% 1-2 mm, 91% <1 mm) were granulated by adding calcium oxide and concentrated sulphuric acid using a rotating drum in the laboratory and pilot plant. The granules had satisfactory physical and chemical properties. The granules made in the pilot plant with 25 kg ammonium sulphate, 0.5 kg CaO, 1.26 litres of water and 0.9 to 1.125 litres of 98.5% H2SO4 had 80 to 97% of the granules within the size range of 1-3 mm, abrasion resistance of 0.4 to 0.8% <1 mm, crushing strength of 1.4 to 2.3 kg, critical relative humidity of 65-70%, pH 1.8 to 1.9 and N, S and Ca contents of 19, 24 and 1%. The quality of the granules when stored for 6 months alone or blended together with common fertilizers did not change. A glass house trial using barley demonstrated that the agronomic values of 4 prototype ammonium sulphate granules produced in the laboratory were similar to 3 standard granular ammonium sulphate fertilizers. The process of granulation which could easily be adopted in superphosphate manufacturing plants is recommended for plant scale testing. © 1992 Kluwer Academic Publishers.
Mukherjee, S & Waldron, KJ 1992, 'An Exact Optimization of Interaction Forces in Three-Fingered Manipulation', Journal of Mechanical Design, vol. 114, no. 1, pp. 48-54.
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Manipulation with three fingers in frictional contact is known to be an underspecified problem. The minimum norm solution, also referred to as the equilibrating solution field, can be modified by superimposing a linear combination of the resulting null solutions, called the interaction force field. The modification proposed here, applicable to the three-dimensional problem, minimizes the maximum value of the friction angle at the points of contract. A grasp of maximum possible stability under a set of contact and loading conditions is hence achieved.
MURTHY, V & WALDRON, KJ 1992, 'POSITION KINEMATICS OF THE GENERALIZED LOBSTER ARM AND ITS SERIES-PARALLEL DUAL', JOURNAL OF MECHANICAL DESIGN, vol. 114, no. 3, pp. 406-413.
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The generalized lobster arm is a six revolute open kinematic chain with 3 consecutive intersecting pairs of axes. A new solution of the inverse position kinematics problem of this arm which takes advantage of its specific geometry is presented. A compari
Nair, SS, Singh, R, Waldron, KJ & Vohnout, VJ 1992, 'Power system of a multi-legged walking robot', Robotics and Autonomous Systems, vol. 9, no. 3, pp. 149-163.
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The power system of a legged vehicle is considerably more complex than the one used by a conventional land vehicle because of the wide range of power demands and the coordination and stability issues due to the large number of degrees of freedom. This paper is concerned with the conceptual and physical characteristics of the power system of a rough terrain, six-legged, walking vehicle. Modelling techniques and detailed analytical and simulation models are developed for the vehicle power system consisting of the prime mover, energy storage system, mechanical drives, hydraulic actuation systems and the associated control systems. Dynamics of the various subsystem and their interactions have been studied for control and optimization purposes. Validation of the models is provided by several experiments performed on a prototype leg and the vehicle. © 1992.
Nakagaki, A, Miyanaga, Y & Tochinai, K 1992, 'Application of modified off‐axis spectrum to speech recognition under noisy conditions', Electronics and Communications in Japan (Part III: Fundamental Electronic Science), vol. 75, no. 3, pp. 102-110.
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AbstractThis paper introduces a peak enhancement method using an off‐axis spectrum which is used in peak picking. It also considers its advantages and problems for the application of speech recognition. An off‐axis model modified to be suitable for speech recognition is proposed. The modified off‐axis model is realized by combining a peak emphasis model and a peak repressed model. The modified off‐axis model can control the peak bandwidths and the slope of its spectrum by operating two parameters. The values of the parameters are determined adaptively to each sample by a stability test. In addition, some results of experimental speech recognition under noisy conditions are described and the efficiency of the method is discussed.
OLLERTON, RL & SHANNON, AG 1992, 'An extension of circular and hyperbolic functionsAn', International Journal of Mathematical Education in Science and Technology, vol. 23, no. 4, pp. 611-635.
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The ordinary circular and hyperbolic functions are extended in a natural way as functions with recurring derivatives. Many of the usual properties are maintained or enhanced and this leads to a deeper understanding of the original functions. © 1992 Taylor and Francis Ltd.
Quek, KH, Bliss, PJ & Ball, JE 1992, 'Hydrodynamics of sedimentation basin (part II)-model validation and application', Transactions of the Institution of Engineers, Australia. Civil engineering, vol. CE34, no. 1, pp. 49-56.
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The calibration and validation of a computationally efficient hydrodynamic model (Quek et al., 1991c) is presented in this paper using previously published data of velocity profiles in a rectangular flume. The hydrodynamic model is applied to study the flow field in a rectangular primary sedimentation basin. The predicted velocity profiles are compared with field measurements obtained by Heinke et al. (1977). The effects of different basin design features on the flow patterns are investigated in this paper by application of the hydrodynamic model.
SAMBROOK, P & NGUYEN, T 1992, 'Vertebral Osteoporosis in Rheumatoid Arthritis Patients: Effect of Low Dose Prednisone Therapy', Rheumatology, vol. 31, no. 8, pp. 573-573.
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Sapiano, PC, Holbeche, RJ, Burnett, IS & Pulley, DR 1992, 'Modulation recognition by neural network techniques', Proceedings of IEEE Int. Symp. on Communications.
STEWART, MG 1992, 'A HUMAN RELIABILITY ANALYSIS OF REINFORCED CONCRETE BEAM CONSTRUCTION', Civil Engineering Systems, vol. 9, no. 3, pp. 227-250.
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A significant proportion of performance failures (c.g., structural failure, cost overruns, delays) are due to human error in the construction of in-situ reinforced concrete elements. A Human Reliability Analysis (HRA) model has been developed to simulate the effect of human error on the construction of a reinforced concrete beam. The proposed HRA model incorporates the effect of (i) initial errors (i.e., before engineering inspections) and (ii) errors remaining after engineering inspections. The following typical construction tasks are considered: number and size of reinforcing bars, effective depth of steel reinforcing, beam width, and quality of concrete mix. Human performance models are described for each of these microtasks. It was found that human error leads to a significant loss of structural safety. It was also shown that engineering inspections significantly increased structural reliability, but the resulting structural reliability was still an order of magnitude lower than “nominal” estimates of structural reliability. © 1992, Taylor & Francis Group, LLC. All rights reserved.
Stewart, MG 1992, 'Modelling human error rates for human reliability analysis of a structural design task', Reliability Engineering & System Safety, vol. 36, no. 2, pp. 171-180.
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It is generally accepted that human error, particularly in design, causes a significant proportion of structural failures. It is necessary to understand the 'micro' (or single task) behaviour of human errors before the entire system can be modelled. Reported herein is a description of proposed mathematical models of error occurrence that are suitable for use in a Human Reliability Analysis (HRA). These models may be used to provide error rate information. These models are fitted to realistic error occurrence data. The data was obtained from practising professional engineers and the tasks performed were cognitive; namely, calculation, table look-up and ranking tasks. These tasks are commonly encountered in typical design calculations. It was found that error occurrence behaviour is characterised by variation of error rates between individuals and, to a lesser extent, correlation of error rates for individuals. The effect of response time and experience were also examined. A comparison of the effect on structural reliability (for a typical structural design task) for error occurrence (based on the proposed models) is also reported. © 1992.
Stewart, MG 1992, 'Simulation of human error in reinforced concrete design', Research in Engineering Design, vol. 4, no. 1, pp. 51-60.
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Available statistical data suggest that human error in design causes a significant proportion of performance failures; namely, structural failure, cost overruns, and delays. A Human Reliability Analysis (HRA) model has been developed to simulate the effect of human error on the design computations of a reinforced concrete beam. The proposed HRA model incorporates the effect of 'self-corrections'; this is a process where tasks are re-evaluated if the result appears to be not within 'reasonable' expectations. Calculation, table look-up, chart look-up, and table ranking microtasks were incorporated into the proposed HRA model; human perormance data are described for each of these microtasks. It was found that human error, particularly multiple errors, lead to a significant loss of structural safety. © 1992 Springer-Verlag New York Inc.
Veitch, D 1992, 'Windows of stability in control chaos', IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, vol. 39, no. 10, pp. 808-819.
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WATTERSON, PA, ZHU, JG & RAMSDEN, VS 1992, 'OPTIMIZATION OF PERMANENT-MAGNET MOTORS USING FIELD CALCULATIONS OF INCREASING PRECISION', IEEE TRANSACTIONS ON MAGNETICS, vol. 28, no. 2, pp. 1589-1592.
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An algorithm is given for the fast optimization over a constrained domain of an objective function calculated iteratively. To apply the algorithm to optimizing the efficiency of permanent magnet synchronous motors, an iterative magnetic field calculatio
Zhengneng, L & Li, J 1992, 'Study on the single-peak over-load retardation effect of three-dimensional small cracks', Acta Aeronautica et Astronautica Sinica, vol. 3.
Zhou, JL 1992, 'Biosorption and desorption of humic acid by microbial biomass', Chemosphere, vol. 24, no. 11, pp. 1573-1589.
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Zhou, JL & Banks, CJ 1992, 'Humic acid removal from water by biosorptton', Environmental Technology, vol. 13, no. 8, pp. 727-737.
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Avenel, O, Xu, J, Xia, JS, Xu, M-F, Andraka, B, Lang, T, Moyland, PL, Ni, W, Signore, PJC, van Woerkens, CMCM, Adams, ED, Ihas, GG, Meisel, MW, Nagler, SE, Sullivan, NS, Takano, Y, Talham, DR, Goto, T & Fujiwara, N 1970, 'Low temperature magnetic measurements of NENP', Journal of Low Temperature Physics, SYMP ON QUANTUM FLUIDS AND SOLIDS, Springer Science and Business Media LLC, PA, PENN STATE UNIV, UNIVERSITY PARK, pp. 547-550.
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Bawab, S, Kinzel, GL & Waldron, KJ 1970, 'Rectified Synthesis of Coupler-Driven Four-Bar Mechanisms for Four-Position Motion Generation', 22nd Biennial Mechanisms Conference: Mechanism Design and Synthesis, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract A rectified synthesis procedure for designing coupler-driven four-bar mechanisms to pass a moving lamina through four precision positions is developed. The procedure includes the elimination of circuit, branch and order defects. This is achieved with the aid of Roberts’ linkage. The procedure has been implemented in the interactive synthesis package RECSYN.
Bawab, S, Kinzel, GL & Waldron, KJ 1970, 'Rectified synthesis of coupler-driven four-bar mechanisms for four-position motion generation', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 147-155.
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A rectified synthesis procedure for designing coupler-driven four-bar mechanisms to pass a moving lamina through four precision positions is developed. The procedure includes the elimination of circuit, branch and order defects. This is achieved with the aid of Roberts' linkage. The procedure has been implemented in the interactive synthesis package RECSYN.
DUCHIEN, L, GAY, V & HORLAIT, E 1970, 'DESIGN OF AN INTEGRATED X400 FILESTORE', UPPER LAYER PROTOCOLS, ARCHITECTURES AND APPLICATIONS, IFIP TC6/WG6.5 International Conference on Upper Layer Protocols, Architectures and Applications, ELSEVIER SCIENCE PUBL B V, VANCOUVER, CANADA, pp. 395-407.
Guo, YJ & Barton, SK 1970, 'Flat printed zone plate antennas for DBS reception', IEE Conference Publication, pp. 355-358.
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A systematic investigation on flat printed phase correcting zone plate reflector antennas is presented. A multi-layered structure is proposed and a circular quarter-wave zone plate reflector with 54.8% efficiency is reported. When the zone plate reflector is offset, the circular zones become elliptical ones with their centers moved away successively from where the feed is pointed at. Experimental results on an offset half-wave zone plate reflector is given. Unfortunately, the antenna sidelobe level shown in the paper is much worse than that of the CCIR standard, which presently limits the zone plate reflectors as reception-only antennas. However, more recent experiments have shown that the sidelobes of the quarter-wave zone plate reflectors can be significantly improved by introducing better phase compensation and various approaches are being investigated.
Guo, YJ & Barton, SK 1970, 'On the sidelobe performance of Fresnel zone plate antennas', IEEE Antennas and Propagation Society International Symposium 1992 Digest, IEEE Antennas and Propagation Society International Symposium 1992 Digest, IEEE, pp. 2175-2178.
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Husain, M & Waldron, KJ 1970, 'Direct Position Kinematics of the 3-1-1-1 Stewart Platforms', 22nd Biennial Mechanisms Conference: Robotics, Spatial Mechanisms, and Mechanical Systems, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract In this work, a closed form solution for the direct position kinematics problem of a special class of Stewart Platform is presented. This class of mechanisms has a general feature that the top platform is connected to the six limbs at four locations. Three limbs connect at one location and the remaining limbs connect to the top platform singly at three separate locations. The base platform is connected at six different locations as is the case in the general platform. This particular class of mechanism is termed as 3-1-1-1 mechanism in this paper. It has been shown that there are a maximum of sixteen real assembly configurations for the direct position kinematics problem. This has been verified using a geometric argument also. The numerical example solved in this paper demonstrates that it is possible to obtain a set of solutions which are all real.
Husain, M & Waldron, KJ 1970, 'Direct position kinematics of the 3-1-1-1 Stewart platforms', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 89-97.
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In this work, a closed form solution of the direct position kinematics problem of a special class of Stewart Platform is presented. This class of mechanisms has a general feature that the top platform is connected to the six limbs at four locations. Three limbs connect at one location and the remaining limbs connect to the top platform singly at three separate locations. The base platform is connected at six different locations as is the case in the general platform. This particular class of mechanism is termed as 3-1-1-1 mechanism in this paper. It has been shown that there are a maximum of sixteen real assembly configurations for the direct position kinematics problem. This has been verified using a geometric argument also. The numerical example solved in this paper demonstrates that it is possible to obtain a set of solutions which are all real.
Husain, M & Waldron, KJ 1970, 'Position kinematics of a mixed mechanism', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 41-47.
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Although robotics has traditionally focused on the serial chain structures typical of industrial robots, fully parallel structures such as the Stewart Platform have also found considerable industrial use. Actively coordinated mechanisms which have combinations of serial and parallel characteristics have been practically employed, and can be expected to become more important in the future. There has been very little study of the kinematic and static characteristics of these mechanisms which have been combinations of the characteristics of fully serial and fully parallel structures. This work addresses the direct and inverse position kinematics of such a hybrid mechanism with combination of serial and parallel structure which has multiple, actively controlled actuators. While not the most general possible configuration, this particular case does include many important features of the general mechanism, and the solution obtained gives useful insight for developing a general theory of forward and inverse kinematics which will be equally applicable to serial, parallel and combination structures. Such a theory is necessary for rational design of hardware and software for such systems.
Husain, M & Waldron, KJ 1970, 'Position Kinematics of a Mixed Mechanism', 22nd Biennial Mechanisms Conference: Robotics, Spatial Mechanisms, and Mechanical Systems, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract Although robotics has traditionally focused on the serial chain structures typical of industrial robots, fully parallel structures such as the Stewart Platform have also found considerable industrial use. Actively coordinated mechanisms which have combinations of serial and parallel characteristics have been practically employed, and can be expected to become more important in the future. There has been very little study of the kinematic and static characteristics of these mechanisms which have combinations of the characteristics of fully serial and fully parallel structures. This work addresses the direct and inverse position kinematics of such a hybrid mechanism with combination of serial and parallel structure which has multiple, actively controlled actuators. While not the most general possible configuration, this particular case does include many important features of the general mechanism, and the solution obtained gives useful insight for developing a general theory of forward and inverse kinematics which will be equally applicable to serial, parallel and combination structures. Such a theory is necessary for rational design of hardware and software for such systems.
Miyanaga, Y & Tochinai, K 1970, 'An adaptive recognition using self-organized network', [Proceedings] 1992 IEEE International Symposium on Circuits and Systems, [Proceedings] 1992 IEEE International Symposium on Circuits and Systems, IEEE, SAN DIEGO, CA, pp. 332-335.
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Nanua, P & Waldron, KJ 1970, 'Instability and Chaos in Quadruped Gallop', 22nd Biennial Mechanisms Conference: Robotics, Spatial Mechanisms, and Mechanical Systems, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract A dynamic model for the two dimensional quadruped has been developed. The main body is modelled as a rigid bar and each leg consists of a constant stiffness spring, a viscous damper and a force actuator. Based on symmetry principles, a controller has been devised that will enable the quadruped to gallop at constant speed. The controller consists of two parts: an energy controller which will apply the required amount of force through the legs, and the speed controller that will control the forward speed by appropriately placing the legs. It will be shown that the body pitch need not be explicitly controlled. The stability of this controller will be examined using Poincare maps. Stable systems show either periodic or quasi-periodic response. This system also exhibits chaotic behavior and chaotic response leads to instability. The stability of the system with changes in the initial conditions, as well as variations in the system parameters, will also be examined. It will be shown that the system is stable for a range of leg stiffnesses. Outside this range, the system shows chaotic behavior.
Nanua, P & Waldron, KJ 1970, 'Instability and chaos in quadruped gallop', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 599-604.
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A dynamic model for the two dimensional quadruped has been developed. The main body is modelled as a rigid bar and each leg consists of a constant stiffness spring, a viscous damper and a force actuator. Based on symmetry principles, a controller has been devised that will enable the quadruped to gallop at constant speed. The controller consists of two parts: an energy controller which will apply the required amount of force through the legs, and the speed controller that will control the forward speed by appropriately placing the legs. It will be shown that the body pitch need not be explicitly controlled. The stability of this controller will be examined using Poincare maps. Stable systems show either periodic or quasi-periodic response. This system also exhibits chaotic behavior and chaotic response leads to instability. The stability of the system with changes in the initial conditions, as well as variations in the system parameters, will also be examined. It will be shown that the system is stable for a range of leg stiffnesses. Outside this range, the system shows chaotic behavior.
Song, SM, Lu, FH, Chen, NX & Waldron, KJ 1970, 'Determination of the shortest crank in four position synthesis: a numerical apporach', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 315-321.
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The shortest crank of a four position synthesis can be determined by solving a statically determinate five-bar structure and a set of seven nonlinear equations have been proposed for this purpose. In this paper a numerical method which can directly solve the shortest crank is presented. It is found that a direct implementation of the original seven equations has two problems: many spurious solutions and poor numerical stability. And the spurious solutions are of the following two types: solutions with incorrect signs of angles and solutions with incorrect geometry. In order to solve the problems, a set of ten equations is developed and parameter perturbation method is applied. Furthermore, a set of eight equations is developed for better numerical stability. Both the ten and eight equations can eliminate the spurious solutions with incorrect geometry. Yet the spurious solutions with incorrect signs of angles can only be rectified after convergence. An automatic search algorithm is included to automatically search the shortest crank in the solution space. Many examples are given to illustrate this numerical approach.
Song, S-M, Lu, F-H, Chen, N-X & Waldron, KJ 1970, 'Determination of the Shortest Crank in Four Position Synthesis: A Numerical Apporach', 22nd Biennial Mechanisms Conference: Mechanism Design and Synthesis, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract The shortest crank of a four position synthesis can be determined by solving a statically determinate five-bar structure and a set of seven nonlinear equations have been proposed for this purpose. In this paper a numerical method which can directly solve the shortest crank is presented. It is found that a direct implementation of the original seven equations has two problems: many spurious solutions and poor numerical stability. And the spurious solutions are of the following two types: solutions with incorrect signs of angles and solutions with incorrect geometry. In order to solve the problems, a set of ten equations is developed and parameter perturbation method is applied. Furthermore, a set of eight equations is developed for better numerical stability. Both the ten and eight equations can eliminate the spurious solutions with incorrect geometry. Yet the spurious solutions with incorrect signs of angles can only be rectified after convergence. An automatic search algorithm is included to automatically search the shortest crank in the solution space. Many examples are given to illustrate this numerical approach.
Sreenivasan, SV & Waldron, KJ 1970, 'A Drift-Free Navigation System for a Mobile Robotic Vehicle Operating on Unstructured Terrain', 22nd Biennial Mechanisms Conference: Robotics, Spatial Mechanisms, and Mechanical Systems, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract The orientation and the angular rates of the body of a robotic vehicle are required for guidance and control of the vehicle. In the current robotic systems these quantities are obtained by the use of inertial sensing systems. Inertial sensing systems involve drift errors which can be significant even after the vehicle has traversed only short distances on the terrain. A different approach is suggested here which guarantees accurate, drift-free sensing of the angular position and rates of the vehicle body. A camera system consisting of two cameras in fixed relationship to one another is made to continuously track two stationary objects. The camera system is mounted on the vehicle body through an actuated three degree of freedom joint. The angular positions and rates of these joints can be used to evaluate the angular positions and rates of the vehicle body. An approximate estimate of the position of the vehicle on the terrain can also be obtained from the sensing system. This can serve as primary system for estimating the vehicle position, or as a backup to a more accurate scheme for obtaining the position of the vehicle on the terrain.
Sreenivasan, SV & Waldron, KJ 1970, 'Drift-free navigation system for a mobile robotic vehicle operating on unstructured terrain', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 413-422.
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The orientation and the angular rates of the body of a robotic vehicle are required for guidance and control of the vehicle. In the current robotic systems these quantities are obtained by the use of inertial sensing systems. Inertial sensing systems involve drift errors which can be significant even after the vehicle has traversed only short distances on the terrain. A different approach is suggested here which guarantees accurate, drift-free sensing of the angular position and rates of the vehicle body. A camera system consisting of two cameras in fixed relationship to one another is made to continuously track two stationary objects. The camera system is mounted on the vehicle body through an actuated three degree of freedom joint. The angular positions and rates of these joints can be used to evaluate the angular positions and rates of the vehicle body. An approximate estimate of the position of the vehicle on the terrain can also be obtained from the sensing system. This can serve as primary system for estimating the vehicle position, or as a backup to a more accurate scheme for obtaining the position of the vehicle on the terrain.
Srikrishna, P & Waldron, KJ 1970, 'A Unified Analysis and Implementation of Four Multiply Separated Position Synthesis of Four-Bar Linkages', 22nd Biennial Mechanisms Conference: Mechanism Design and Synthesis, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract The objective of this paper is to derive analytically the circle-point and center-point curve equations for the synthesis of four-bar linkages for rigid body guidance through four multiply separated design positions. A unified approach is evolved to deal with the different combinations of four finitely and infinitesimally separated design position, namely the PP-P-P, PP-PP and PPP-P cases. The design procedure incorporates the rectification procedures developed by Waldron (1977) to eliminate the branch and order problems and is implemented in the interactive synthesis package RECSYN.
Srikrishna, P & Waldron, KJ 1970, 'Unified analysis and implementation of four multiply separated position synthesis of four-bar linkages', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 301-308.
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The objective of this paper is to derive analytically the circle-point and center-point curve equations for the synthesis of four-bar linkages for rigid body guidance through four multiply separated design positions. A unified approach is evolved to deal with the different combinations of four finitely and infinitesimally separated design position, namely the PP-P-P, PP-PP and PPP-P cases. The design procedure incorporates the rectification procedures developed by Waldron (1977) to eliminate the branch and order problems and is implemented in the interactive synthesis package RECSYN.
Venkataraman, SC, Kinzel, GL & Waldron, KJ 1970, 'Optimal synthesis of four-bar linkages for four-position rigid-body guidance with selective tolerance specifications', American Society of Mechanical Engineers, Design Engineering Division (Publication) DE, pp. 651-659.
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In practical rigid-body guidance problems, very often one or more of the design positions need not be generated exactly. Further, extreme accuracy at the design positions is somewhat pointless considering the inherent limitations in linkage manufacturing processes. This emphasizes the requirement of synthesis techniques to be able to handle tolerance specifications on the nominal design positions. A favorable offshoot of the tolerance incorporation would be the accompanying increase in the solution space of the synthesis problem thereby yielding better linkage solutions.
Venkataraman, SC, Kinzel, GL & Waldron, KJ 1970, 'Optimal Synthesis of Four-Bar Linkages for Four-Position Rigid-Body Guidance With Selective Tolerance Specifications', 22nd Biennial Mechanisms Conference: Mechanism Design and Synthesis, ASME 1992 Design Technical Conferences, American Society of Mechanical Engineers.
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Abstract In practical rigid-body guidance problems, very often one or more of the design positions need not be generated exactly. Further, extreme accuracy at the design positions is somewhat pointless considering the inherent limitations in linkage manufacturing processes. This emphasizes the requirement of synthesis techniques to be able to handle tolerance specifications on the nominal design positions. A favorable offshoot of the tolerance incorporation would be the accompanying increase in the solution space of the synthesis problem thereby yielding better linkage solutions.
Waldron, KJ 1970, 'Actively controlled mobility systems', TENCON'92 - Technology Enabling Tomorrow, TENCON'92 - Technology Enabling Tomorrow, IEEE, pp. 332-336.
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© 1992 IEEE. The author discusses the coordination problem which arises in vehicles with large numbers of independently actuated joints designed to operate in unknown terrain. Coordination requires a considerable amount of sensor data. Some of this may be available from sensors required by other machine systems. Other necessary data mandates installation of sensor systems which would not otherwise be required. Much of the technology discussed is based on the adaptive suspension vehicle legged vehicle. An important application area for this technology is in planetary rover vehicles. A number of the diverse designs under study are reviewed with regard to their coordination requirements.
Xia, JS, Ni, W & Adams, ED 1970, 'Order of the PP-HFP transition in solid3He', Journal of Low Temperature Physics, SYMP ON QUANTUM FLUIDS AND SOLIDS, Springer Science and Business Media LLC, PA, PENN STATE UNIV, UNIVERSITY PARK, pp. 355-364.
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Xu, J, Avenel, O, Xia, JS, Xu, M-F, Lang, T, Moyland, PL, Ni, W, Adams, ED, Ihas, GG, Meisel, MW, Sullivan, NS & Takano, Y 1970, 'Nuclear demagnetization cryostat at University of Florida Microkelvin laboratory', Journal of Low Temperature Physics, SYMP ON QUANTUM FLUIDS AND SOLIDS, Springer Science and Business Media LLC, PA, PENN STATE UNIV, UNIVERSITY PARK, pp. 719-722.
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