Bishop, DW, Thomas, PS & Ray, AS 2000, 'Micro Raman characterization of nickel sulfide inclusions in toughened glass', MATERIALS RESEARCH BULLETIN, vol. 35, no. 7, pp. 1123-1128.
View/Download from: Publisher's site
View description>>
Toughened glass panels used as glazing material in multistory buildings are subject to fracture when they contain nickel sulfide inclusions. The failure mechanism is generally attributed to the significant volume increase related to a polymorphic phase retransformation in nickel sulfide. This investigation exploits the ability of micro Raman spectroscopy to analyze minute inclusions. The technique is able to distinguish between different polymorphs and various stoichiometric forms of nickel sulfide and has the potential to satisfy the need for an in situ, nondestructive analytical technique for the characterization of nickel sulfide inclusions in glass.
Gadad, A 2000, 'Synthesis and antibacterial activity of some 5-guanylhydrazone/thiocyanato-6-arylimidazo[2,1-b]-1,3,4-thiadiazole-2-sulfonamide derivatives†', European Journal of Medicinal Chemistry, vol. 35, no. 9, pp. 853-857.
View/Download from: Publisher's site
Gowripalan, N, Sirivivatnanon, V & Lim, CC 2000, 'Chloride diffusivity of concrete cracked in flexure', CEMENT AND CONCRETE RESEARCH, vol. 30, no. 5, pp. 725-730.
View/Download from: Publisher's site
Ha, QP, Nguyen, QH, Rye, DC & Durrant-Whyte, HF 2000, 'Impedance control of a hydraulically actuated robotic excavator', AUTOMATION IN CONSTRUCTION, vol. 9, no. 5-6, pp. 421-435.
View/Download from: Publisher's site
View description>>
In robotic excavation hybrid position/force control has been proposed for bucket digging trajectory following. In hybrid position/force control, the control mode is required to switch between position- and force-control depending on whether the bucket is in free space or in contact with the soil during the process. Alternatively, impedance control can be applied such that one control mode is employed in both free and constrained motion. This paper presents a robust sliding controller that implements impedance control for a backhoe excavator. The control law consists of three components: an equivalent control, a switching control and a tuning control. Given an excavation task in world space, inverse kinematic and dynamic models are used to convert the task into a desired digging trajectory in joint space. The proposed controller is applied to provide good tracking performance with attenuated vibration at bucket-soil contact points. From the control signals and the joint angles of the excavator, the piston position and ram force of each hydraulic cylinder for the axis control of the boom, arm, and bucket can be determined. The problem is then how to find the control voltage applied to each servovalve to achieve force and position tracking of each electrohydraulic system for the axis motion of the boom, arm, and bucket. With an observer-based compensation for disturbance force including hydraulic friction, tracking of the piston ram force and position is guaranteed using robust sliding control. High performance and strong robustness can be obtained as demonstrated by simulation and experiments performed on a hydraulically actuated robotic excavator. The results obtained suggest that the proposed control technique can provide robust performance when employed in autonomous excavation with soil contact considerations. (C) 2000 Elsevier Science B.V. All rights reserved.
Khalili, N, Khabbaz, MH & Valliappan, S 2000, 'An effective stress based numerical model for hydro-mechanical analysis in unsaturated porous media', Computational Mechanics, vol. 26, no. 2, pp. 174-184.
View/Download from: Publisher's site
Lim, CC, Gowripalan, N & Sirivivatnanon, V 2000, 'Microcracking and chloride permeability of concrete under uniaxial compression', CEMENT & CONCRETE COMPOSITES, vol. 22, no. 5, pp. 353-360.
View/Download from: Publisher's site
Partlett, MJ & Thomas, PS 2000, 'Characterization of surface-modified poly(ethylene terephthalate) fibres by inverse gas chromatography', Polymer International, vol. 49, no. 6, pp. 495-500.
View/Download from: Publisher's site
View description>>
The effect of surface cleanliness on the alkaline hydrolysis of poly(ethylene terephthalate) fibres was investigated using inverse gas chromatography (IGC) in conjunction with mass loss measurements and electron microscopy. The sizing agent was removed from the fibre surface by two methods: soxhlet cleaning in acetone and washing in an aqueous solution of a non-ionic detergent. Alkaline hydrolysis was carried out using two concentrations of aqueous sodium hydroxide, 1% and 10% by mass. The measurement of the specific retention volume of undecane and the heat of adsorption using IGC indicated that the acetone cleaned samples were essentially surface contaminant free, while partial contamination of the surface by the sizing agent remained in the detergent cleaned samples. The presence of sizing agent significantly altered the degree of hydrolysis and the surface topography. The increasing values of the heat of adsorption indicated that significant surface hydrolysis increased the surface crystallinity.
Partlett, MJ & Thomas, PS 2000, 'Characterization of surface-modified poly(ethylene terephthalate) fibres by inverse gas chromatography', Polymer International, vol. 49, no. 6, pp. 495-500.
View/Download from: Publisher's site
Stuart, BH & Thomas, PS 2000, 'The characterisation of plastic used in a Gabo sculpture', POLYMER TESTING, vol. 19, no. 8, pp. 953-957.
View/Download from: Publisher's site
Thomas, P & Ray, AS 2000, 'Processing initiated failure of toughened glass panels', Chemistry in Australia, vol. 67, no. 6, pp. 12-14.
Trinh, H & Ha, Q 2000, 'Design of linear functional observers for linear systems with unknown inputs', International Journal of Systems Science, vol. 31, no. 6, pp. 741-749.
View/Download from: Publisher's site
View description>>
This paper presents a reduced-order linear functional state observer for linear systems with unknown inputs. A simple observer construction procedure is provided. A numerical example is given to illustrate the properties of the observer. The example deals with a linear system comprising of 20 states, 2 inputs, 10 outputs and 5 unknown inputs for which a fourth-order observer is designed to estimate two linear functions of the states.
Wang, J & Yan, H 2000, 'A hybrid method for unconstrained handwritten numeral recognition by combining structural and neural “gas” classifiers', Pattern Recognition Letters, vol. 21, no. 6-7, pp. 625-635.
View/Download from: Publisher's site
View description>>
Abstract: This paper presents a hybrid method for handwritten numeral recognition that combines two compensatory recognition algorithms by analysing their performance for several aspects. The skeleton-based structural recognition algorithm employed in this method is robust under distortion but sensitive to noise and flaws. On the other hand, the neural network classifier, which uses scaled binary images as features and the neural "gas" model for classification, is relatively immune to noise and flaws but sensitive to distortion. The different performances of the two algorithms for broken, connected or slanted numerals, and the measurement-level decision provided by the neural network are detected and combined with different strategies to develop matching rules for each recognition method. Five combination methods based on performance analysis are developed to meet different requirements. As the two algorithms have fairly compensatory properties, the proposed method improves the recognition rate and reliability by exploiting the advantages and avoiding the weaknesses of each classifier. The experimental results from a large set of data show the efficiency and robustness of the proposed method.
Wu, C, Hao, H & Zhou, Y 2000, 'Statistical Properties of the Bukit Timah Granite in Singapore', Journal of Testing and Evaluation, vol. 28, no. 1, pp. 36-43.
View/Download from: Publisher's site
View description>>
AbstractThe mechanical behavior of rock mass is affected strongly by its material properties. This paper carries out statistical analyses of the material properties of a rock mass. Statistical analyses of the material constants and the initial damage parameter of the rock mass are performed by using both field and laboratory test data. Based on the measured properties of rock specimens, the elastic modulus, uniaxial compressive strength, and the Poisson's ratio of rock are each found to have normal distributions and the tensile strength to have the gamma distribution. By using Monte Carlo simulation, the equivalent critical tensile strain is found to have the normal distribution. The initial damage of the rock mass, which describes the effects of naturally existing geological discontinuities in a rock mass, is estimated using the field-measured longitudinal and transverse elastic wave velocities. It is found to have the beta distribution. These distributions of rock properties can be used in statistical analyses of the rock mass responses to both static and dynamic loads.
Zhang, XP, Wang, CH, Li, JC, Mai, YW & Ye, L 2000, 'A Combined Model of Short Crack Closure Accounting for Both Plasticity and Roughness Induced Crack Closures', Key Engineering Materials, vol. 183-187, pp. 217-222.
View/Download from: Publisher's site
Zhang, XP, Wang, CH, Li, JC, Mai, YW & Ye, L 2000, 'Combined model of short crack closure accounting for both plasticity and roughness induced crack closures', Key Engineering Materials, vol. 183.
View description>>
A new model combining both plasticity-induced and surface roughness-induced crack closures is proposed to describe short fatigue crack growth. The numerical results obtained using this model agree well with the analytical predictions of Budiansky-Hutchinson and are reasonably close to the experimental data.
Crews, KI 1970, 'Development of limit states design methods for stress-laminated timber cellular bridge decks', World Conference on Timber Engineering 2000, World Conference on Timber Engineering, University of British Columbia, Vancouver, Canada, pp. 0-0.
Crews, KI 1970, 'Strength assessment of timber', World Conference on Timber Engineering 2000, World Conference on Timber Engineering, University of British Columbia, Vancouver, Canada, pp. 0-0.
Ding, GK 1970, 'MCDM and the sustainable assessment of projects', Cities & Sustainability-sustaining our cultural heritage, The Millennium Conference, Univeristy of Salford, Sri Lanka, pp. 1-11.
Hao, H & Wu, CQ 1970, 'Numerical modeling of underground explosion-induced stress wave propagation in rock mass', WAVE 2000: WAVE PROPAGATION, MOVING LOAD, VIBRATION REDUCTION, WAVE 2000 International Workshop, A A BALKEMA PUBLISHERS, BOCHUM, GERMANY, pp. 369-378.
Nguyen, HT, Ha, QP, Rye, D & Durrant-Whyte, H 1970, 'Low level control of electrohydraulic systems', Japan-USA-Vietnam Workshop on research and education in systems, computation and control engineering, Institute of Applied Mechanics NCSR Vietnam, HochiMinh City Vietnam, pp. 281-291.
Nguyen, QH, Ha, QP, Rye, DC & Durrant-Whyte, HF 1970, 'Force/position tracking for electrohydraulic systems of a robotic excavator', Proceedings of the 39th IEEE Conference on Decision and Control (Cat. No.00CH37187), 39th IEEE Conference on Decision and Control, IEEE, pp. 5224-5229.
View/Download from: Publisher's site
View description>>
This paper presents the sliding mode axis control of the electrohydraulic servo systems of a robotic excavator. The dynamic systems are described by a comprehensive model that accounts for nonlinearities and friction effects of asymmetric hydraulic cylinders. A sliding mode controller is developed for the electrohydraulic actuator of each working axis to provide stable force tracking. With a proper choice of the reference force, the control law can also allow tracking of a desired piston displacement trajectory. Numerical simulation demonstrates the validity of the proposed technique. Experimental results show good performance and strong robustness in both force and position following.
