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.
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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.
Blunden, BG & Indraratna, B 2000, 'Evaluation of surface and groundwater management strategies for drained sulfidic soil using numerical simulation models', Soil Research, vol. 38, no. 3, pp. 569-569.
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The effective management of acid sulfate soils is a major issue for manycoastal regions in Australia. Simulations were conducted to evaluate 4different water management strategies that could be applied to agriculturalland on the south coast of New South Wales, Australia, to minimise acidgeneration from acid sulfate soils. The water management strategies arecompared with the existing extensively drained situation which generates anddischarges large quantities of acidic pyrite oxidation products. The 4 watermanagement strategies include elevated drain water levels using a weir, 25 mmirrigation on a 7- or 14-day cycle, and elevated drain water levels withirrigation. All of these strategies were designed to minimise the generationof acid by reducing the transport of oxygen to the sulfidic soil. Simulationswere conducted for weather and site conditions experienced during a 12-monthperiod starting in July 1997.Model simulations showed that maintenance of elevated drain water levels usinga weir in the drain significantly reduced the amount of acid generated by75% and 57%, at 10 and 90 m distance from the drain,respectively, by comparison with the existing drained state. The addition of25 mm irrigation on a 14-day cycle to the weir simulation reduced theoxidation of pyrite by a further 1–2%. Application of irrigationonly on a 7-day cycle also reduced the acid generated by 89% and94% at 10 and 90 m distance from the drain, respectively, by comparisonwith the existing drained state. Irrigation on a 14-day cycle was not assuccessful in reducing pyrite oxidation as either the 7-day irrigation or weirstrategies. Evaluation of the 4 water management options showed thatsignificant improvements can be made with respect to the amount of acidgenerated by relatively simple and cost-effective land management practices.
Castel, A, François, R & Arliguie, G 2000, 'Mechanical behaviour of corroded reinforced concrete beams—Part 1: Experimental study of corroded beams', Materials and Structures, vol. 33, no. 9, pp. 539-544.
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Castel, A, François, R & Arliguie, G 2000, 'Mechanical behaviour of corroded reinforced concrete beams—Part 2: Bond and notch effects', Materials and Structures, vol. 33, no. 9, pp. 545-551.
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Cronin, SJ, Manoharan, V, Hedley, MJ & Loganathan, P 2000, 'Fluoride: A review of its fate, bioavailability, and risks of fluorosis in grazed-pasture systems in New Zealand', NEW ZEALAND JOURNAL OF AGRICULTURAL RESEARCH, vol. 43, no. 3, pp. 295-321.
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Fluoride (F) is an essential element for animal growth, not readily taken up by plants from soils, yet cases of acute fluorosis in grazing animals caused by ingestion of phosphatic fertilisers, volcanic ash, and industrial wastes remind us of its potential hazard. Fluoride concentrations in topsoils slowly increase where annual inputs through atmospheric pollution and phosphatic fertilisers exceed losses. This paper reviews information on the fate of F in grazed pasture systems with the aim of assessing the potential toxicity of accumulating soil F. A preliminary F-cycling model for grazed pastures, based on the review of international literature and F concentrations in selected New Zealand pasture soils, indicated that grazing sheep and cattle obtain over 50% of their dietary F (and this may be >80% during winter) from soil ingestion. The model suggests that at the extremes of the ranges of the measured winter soil ingestion (143–300 g d-1 for sheep and 900–1600 g d-1 for cattle) and dietary F absorptivity (bioavailability) of soil F (20–38%), total topsoil F concentrations in the range of 372–1461 μg F g-1 could cause chronic fluorosis in sheep and 326–1085 μg F g-1in cattle. We recommend that research is undertaken to measure F accumulation rates and soil F dietary absorptivity for a range of intensively managed New Zealand pasture soils. © 2000 Taylor & Francis Group, LLC.
Dharmappa, HB, Corderoy, RM & Hagare, P 2000, 'Developing an interactive multimedia software package to enhance understanding of and learning outcomes in water treatment processes', Journal of Cleaner Production, vol. 8, no. 5, pp. 407-411.
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Teaching and learning environments which use multimedia based resources greatly improve the effectiveness and efficiency of learning by engaging students at a deeper level than may otherwise be possible. This is particularly so in situations where `real world' phenomena and processes are being taught. Using such a multimedia package in teaching pollution control processes is novel. This paper reports on the successful development of a multimedia package dealing with several pollution control processes and its evaluation. The pollution control processes illustrated in the multimedia software are physico-chemical processes which are widely used in both water and wastewater treatment. Teaching the design concepts for these processes in a conventional classroom setting is challenging because students have difficulty in visualizing the techniques and processes involved. This difficulty is compounded by the fact that many of the processes occur naturally over longer time periods and so cannot be easily be integrated into normal teaching environments. The software package incorporates several different media modes including text, drawings, photographs, animation, and simulation. The preliminary pilot evaluation of this package using third year engineering students indicated that it provided greater insight and understanding of the complex treatment processes being taught.
Faber, MH, Val, DV & Stewart, MG 2000, 'Proof load testing for bridge assessment and upgrading', Engineering Structures, vol. 22, no. 12, pp. 1677-1689.
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Bridge deterioration with time and ever increasing traffic loads raise concerns about reliability of aging bridges. One of the ways to check reliability of aging bridges is proof load testing. A successful proof load test demonstrates immediately that the resistance of a bridge is greater than the proof load. This reduces uncertainty in the bridge resistance and so increases the bridge reliability. The paper considers a reliability-based calibration of intensities of proof loads for aging bridges to verify either an existing or increased load rating taking into account possible bridge deterioration. Intensities of proof loads are calibrated based on a consistent target reliability index. The influence of test risk, dead to live load ratio, and uncertainties associated with dead and live loads and bridge resistance is considered. The results presented in the paper relate to short and medium span bridges. © 2000 Elsevier Science Ltd.
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.
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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.
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Indraratna, B & Redana, IW 2000, 'Numerical modeling of vertical drains with smear and well resistance installed in soft clay', Canadian Geotechnical Journal, vol. 37, no. 1, pp. 132-145.
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This study describes the behavior of embankments stabilized with prefabricated vertical drains installed in soft clay foundations, based on several fully instrumented case histories selected from Thailand and Malaysia. A multidrain analysis is conducted based on an equivalent, plane strain model developed by the authors. The deformation of soft clay beneath an embankment (i.e., along and away from the centerline) is predicted and compared with the available field measurements. The effects of both smear and well resistance are incorporated in the analytical formulation, which is used in conjunction with the modified Cam-clay theory. It is demonstrated that the installation of vertical drains significantly increases the rate of settlement, improves the dissipation of pore-water pressure, and decreases the lateral deformation of the soft clay foundation. To obtain better predictions, especially of pore pressures and lateral displacements, the equivalent discharge capacity of the drains needs to be modeled appropriately. The inclusion of the effects of smear and well resistance in the analysis of vertical drains improves the accuracy of predictions significantly, in comparison with the field measurements.Key words: clay, consolidation, embankment, finite element method, settlement, smear zone, vertical drain.
Indraratna, B & Redana, IW 2000, 'Numerical modeling of vertical drains with smear and well resistance installed in soft clay', Canadian Geotechnical Journal, vol. 37, no. 1, pp. 132-145.
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Indraratna, B, Nemcik, JA & Gale, WJ 2000, 'Review and interpretation of primary floor failure mechanism at a longwall coal mining face based on numerical analysis', Géotechnique, vol. 50, no. 5, pp. 547-557.
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This paper describes the conceptual model of primary rock failure mechanisms in the floor ahead of the longwall coal mining face based on underground observations and numerical modelling. During longwall mining, the stress fields and displacements of strata are constantly changing. High stress concentrations ahead of the longwall face can initiate fractures in the rock floor that can, under unfavourable stress conditions, develop into secondary floor failure, where large displacements of strata can occur. Severely broken floor strata or floor heave can seriously interfere with mining operations. Underground observations indicate that the sub-vertical shear fractures and the shear failure along the bedding planes in stratified rock are the most common fracture types observed in the rock floor below the longwall face. To explain how these fractures occur, basic principles of rock failure mechanism are applied to an overstressed rock subject to stress concentrations typically found at the longwall face. The computational simulation of the progressive longwall mining operations was undertaken in stratified rock to model complex stress distributions ahead of the longwall face and to simulate the rock failure in the mining floor. The model indicates that the shear fractures and the bedding plane failure dominate the floor failure ahead of the moving longwall face, as was observed underground.
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.
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LAW, SS & ZHU, XQ 2000, 'STUDY ON DIFFERENT BEAM MODELS IN MOVING FORCE IDENTIFICATION', Journal of Sound and Vibration, vol. 234, no. 4, pp. 661-679.
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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.
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Luk, KC, Ball, JE & Sharma, A 2000, 'A study of optimal model lag and spatial inputs to artificial neural network for rainfall forecasting', JOURNAL OF HYDROLOGY, vol. 227, no. 1-4, pp. 56-65.
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Mitchell, AD, Loganathan, P, Payn, TW & Tillman, RW 2000, 'Magnesium fertiliser dissolution rates in pumice soils under Pinus radiata', AUSTRALIAN JOURNAL OF SOIL RESEARCH, vol. 38, no. 3, pp. 753-767.
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Application of Mg fertilisers has been suggested as a means of reducing the incidence of Mg deficiency of forest trees in New Zealand and Europe. The objective of this study was to determine the rates of dissolution of a range of Mg fertilisers applied to a pumice soil (Typic Udivitrand). The rate of fertiliser dissolution was little influenced by whether the fertiliser was applied directly on to the soil surface (litter removed) or on to the litter layer in a Pinus radiata plantation. Twenty-seven months since fertiliser application the mean (with and without litter) percentage of Mg dissolved was in the sequence: Epsom salts > calcined magnesite 1-2 mm > granmag (a partially acidulated and granulated calmag product) > calcined magnesite 2-4 mm > forestry grade dolomite. The specific dissolution rate constants (μg/cm2.day of fertiliser) for the slowly soluble Mg fertilisers calculated using an elemental sulfur oxidation cubic model were 587 for calcined magnesite 1-2 mm, 426 for calcined magnesite 2-4 mm, 385 for granmag, and 18 for forestry grade dolomite. In a laboratory incubation study the elemental sulfur oxidation cubic model described the rate of dissolution of Mg fertilisers within narrow fertiliser particle size ranges. The specific fertiliser dissolution rate constants, however, increased with decreases in particle size, suggesting that the rate of dissolution depends on factors other than surface area when particle sizes varied widely. Slowly soluble, alkaline Mg fertilisers had a significant liming effect on the soil. They were more effective in increasing soil exchangeable Mg than soluble Mg salts over a long-period and therefore, they are better fertilisers for P. radiata.
Nemcik, JA 2000, 'Floor failure analysis at a longwall mining face based on the multiple sliding block model', Geotechnical and Geological Engineering, vol. 18, no. 3, pp. 175-192.
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This paper presents an analytical model of a floor failure at a longwall coal mining face based on the multiple sliding block model. During longwall mining, stresses and displacements of strata are constantly changing. High stress concentrations at the coal face can exceed the rock strength and initiate fractures in the strata that can, under unfavourable conditions, lead to large floor displacements and disruption of mining operations. Underground observations of the rock floor and the computational modelling of the longwall face indicate that two types of fracture dominate floor failure. Extensive lateral fracturing often develops along the numerous weak bedding planes that are typically present in the sedimentary strata while sub-vertical fractures form in response to changing stress abutments ahead of the longwall coal face. The fractures that initially develop ahead of the longwall face are subject to a "secondary" movement when exposed ahead of the longwall supports. In response to the stress relief as the coal is mined from above. Strata move towards the opening and bending of the floor occurs. If fractures in the floor exist, the floor blocks will displace in response to the floor movement and interact at the fractured surfaces. This analysis attempts to explain how the stress distribution develops within the broken floor during an active movement of floor strata leading to high stress concentrations at the floor level. The analytical formulation in this paper is supplemented by numerical modelling, and results are presented to verify that the analytical solutions are in accordance with the numerical predictions.
Ngo, HH, Vigneswaran, S, Kim, SH, Bidkar, A & Moon, H 2000, 'Microfiltration-adsorption hybrid system in organics removal from water', Water Science and Technology, vol. 41, no. 10-11, pp. 51-57.
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A series of experiments was conducted with a Millipore flat plate microfiltration module modified to incorporate in-line powdered activated carbon (PAC) addition. In-line PAC was mixed continuously through a spiral mixing device for a predetermined time prior entering a membrane unit. The results showed that this system is excellent in removing fulvic acid (FA). This system provides to sufficient contact time for PAC to adsorb organics compared to the system with in-line adsorbent addition. More than 85% of FA was removed from water containing 8 mg/l of FA. To achieve this following conditions were used:.(i) a velocity gradient G (mixing intensity) of 160.4 s–1; (ii) a hydraulic residence time (mixing time) of 4 minutes; (iii) a PAC dose of 260 mg/l; and (iv) membrane pore size of 0.22 μm. In case of low FA concentration (e.g. 1.2 mg/l) in water, the removal efficiency was almost 100%. The removal efficiency also increased with the increase of mixing intensity and mixing time. The permeate flux slightly improved when a membrane of pore size 0.22 μm was used with shorter hydraulic residence time and lower PAC concentration. This paper presents a mathematical model developed based on surface diffusion. The model successfully predicted the performance of this hybrid system.
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.
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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.
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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.
PRADHAN, B & KUMAR, S 2000, 'Finite Element Analysis of Low-Velocity Impact Damage in Composite Laminates', Journal of Reinforced Plastics and Composites, vol. 19, no. 4, pp. 322-339.
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Pradhan, B & Kumar, S 2000, 'Finite Element Analysis of Low-Velocity Impact Damage in Composite Laminates', Journal of Reinforced Plastics and Composites, vol. 19, no. 4, pp. 322-339.
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This paper investigates the low-velocity impact behaviour and impact-induced damages in graphite/epoxy composite laminates. A three-dimensional finite element and transient dynamic analysis is performed to calculate the time-varying displacements, forces, strains and stresses throughout the laminate resulting from transverse impact. A layered version of an eight-noded isoparametric brick element with incompatible modes is used to model the laminate. Transient dynamic equilibrium equation is integrated step-by-step with respect to time using Newmark direct time integration method. Modified Hertzian contact law is used to model the local contact behaviour. Appropriate three-dimensional failure criteria are used for predicting the occurrence of matrix cracking and the extent of delamination after impact.
Rosowsky, DV, Stewart, MG & Khor, EH 2000, 'Early-age loading and long-term deflections of reinforced concrete beams', ACI Structural Journal, vol. 97, no. 3, pp. 517-524.
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This paper examines the effects of early-age (construction) loads on the long-term deflections of reinforced concrete (RC) flexural members. Particular consideration is given to simply supported, singly reinforced rectangular beams. The probabilistic analysis of time-dependent deflections takes into account concrete maturation, nonlinear creep and shrinkage behavior, and load process models for both service and construction. While this paper summarizes the time-dependent analysis technique (reported in detail elsewhere), the focus of this paper is on evaluating the effects of early-age loading on the long-term deflection and on practical implications for deflection serviceability design of RC members.
Sargent, CJ, Bowman, JC & Zhou, JL 2000, 'Levels of antifoulant irgarol 1051 in the Conwy Marina, North Wales', Chemosphere, vol. 41, no. 11, pp. 1755-1760.
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Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an antifouling agent used in paint formulations that are applied to the hulls of ships. A survey was carried out at Conwy Marina in North Wales to determine the levels of the herbicide over a period of three months. Liquid/liquid extraction was used to concentrate the analyte for quantitative analysis using gas chromatography/mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode. The concentrations of Irgarol 1051 in Conwy marina ranged from 7 to 543 ng/l, similar to the levels found in many other marinas, estuaries and ports in England, although much lower than those in Cote d’Azur, France. The concentrations of Irgarol 1051 were not found to be influenced by salinity, pH or temperature, although there is a strong correlation between the average concentrations of Irgarol 1051 and the density of boating activity. At the levels found in the marina, it is possible that non-target photosynthetic inhibition could occur. © 2000 Elsevier Science Ltd.
Stuart, BH & Thomas, PS 2000, 'The characterisation of plastic used in a Gabo sculpture', POLYMER TESTING, vol. 19, no. 8, pp. 953-957.
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Thomas, P & Ray, AS 2000, 'Processing initiated failure of toughened glass panels', Chemistry in Australia, vol. 67, no. 6, pp. 12-14.
Val, DV, Stewart, MG & Melchers, RE 2000, 'Life‐Cycle Performance of RC Bridges: Probabilistic Approach', Computer-Aided Civil and Infrastructure Engineering, vol. 15, no. 1, pp. 14-25.
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This article addresses the problem of reliability assessment of reinforced concrete (RC) bridges during their service life. First, a probabilistic model for assessment of time‐dependent reliability of RC bridges is presented, with particular emphasis placed on deterioration of bridges due to corrosion of reinforcing steel. The model takes into account uncertainties associated with materials properties, bridge dimensions, loads, and corrosion initiation and propagation. Time‐dependent reliabilities are considered for ultimate and serviceability limit states. Examples illustrate the application of the model. Second, updating of predictive probabilistic models using site‐specific data is considered. Bayesian statistical theory that provides a mathematical basis for such updating is outlined briefly, and its implementation for the updating of information about bridge properties using inspection data is described in more detail. An example illustrates the effect of this updating on bridge reliability.
Vigneswaran, S, Ngo, HH, Hashimoto, K, Hasegawa, T & Watanabe, Y 2000, 'High rate floating medium flocculation-filtration with in-line polysilicato-iron (PSI) addition', ENVIRONMENTAL TECHNOLOGY, vol. 21, no. 3, pp. 317-325.
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The performance of a high rate floating medium flocculation-filtration system with an in-line addition of a silica-polymer compound, namely polysilicato-iron (PSI) has been investigated for water treatment. This study is intended to investigate the applicability of PSI as a sole flocculant or as a combined flocculant with an organic polymer in the downflow floating medium filter. The filter system was operated at a high loading rate of up to 60 m3 m-2 h-1. Filter column experiments were conducted at different PSI doses, filtration rates, filter depths and buoyant medium types and sizes. Results showed the filter system was able to yield uniform and filterable flocs (15 - 20 µm), even at a very high filtration rate of 60 m-3 h-1, through out the filter run time of 4 hours. Better filter performance was obtained when: (i) polystyrene beads of 1.9 mm diameter or polypropylene beads of 3.8 mm diameter; (ii) an in-line single dosage of 2.5 mg l-1 PSI; (iii) in-line combined dosages of 1.5 mg l-1 PSI and 0.4-0.6 mg l-1 organic polymers (cationic polyacrylamides, cationic polystyrene or Pollyallylamine hydrochloride) were used. When PSI was introduced as a sole flocculant, more than 90% turbidity was removed from a 54 NTU artificial kaolin clay suspension at a filtration rate of 30 m-3 m-2h-1 with very low headloss development. Greater removals were achieved when SIF was used in combination with a polymer (e.g.greater than 95% turbidity removal). Frequent (once in every 90 minutes) but short duration backwash (less than 60 s) by air and water enables the system to maintain a superior effluent quality (e.g. turbidity less than 1 NTU) during the filter run. Backwash water requirement was very low (approximately 1%-2% of filtered water production). A lower amount of sludge was produced from the filter in case of combined PSI and organic polymer coagulant addition.
Vu, KAT & Stewart, MG 2000, 'Structural reliability of concrete bridges including improved chloride-induced corrosion models', Structural Safety, vol. 22, no. 4, pp. 313-333.
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A structural deterioration reliability (probabilistic) model has been used herein to calculate probabilities of structural failure. New reinforced concrete corrosion initiation, corrosion rate and time-variant load models are proposed. Three durability design specifications are considered in a lifetime reliability analysis of a RC slab bridge. Time-variant increases in loads are considered also. It was found that the application of de-icing salts causes significant long-term deterioration and reduction in structural safety for poor durability design specifications. A reduced cover or increased water-cement ratio increases failure probabilities. When compared to the case of 'no deterioration', it was observed also that the probability of failure only marginally increased for good durability design specifications. The approaches described herein are relevant to other physical infrastructure also. © 2000 Elsevier Science Ltd. All rights reserved.
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.
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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.
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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.
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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.
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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.
Zhou, JL & Liu, YP 2000, 'Kinetics and equilibria of the interactions between diethylhexyl phthalate and sediment particles in simulated estuarine systems', Marine Chemistry, vol. 71, no. 1-2, pp. 165-176.
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The sorption of diethylhexyl phthalate (DEHP) by sediment particles has been studied under simulated estuarine conditions, using freshwater and seawater samples collected from the Conwy Estuary, North Wales. The sorption process was rapid, reaching a sorption equilibrium within 6 h at a sediment concentration (SC) of 2.16 g l-1. With an increase in SC, it took longer for the sorption equilibrium to be reached. The sorption equilibrium can be adequately described by the linear partition model at low equilibrium aqueous concentrations. The sorption of DEHP was enhanced in the presence of salts, due to the salting out effect, and a salting constant of 1.156 l mol-1 was obtained. The sorption coefficient of DEHP decreased with increasing SC, from 1.28 x 104 ml g-1 at 0.1 g l-1 SC to 6.75 x 103 ml g-1 at 14.66 g l-1 SC, due to the presence of colloidal particles in suspension which were able to bind DEHP. This third phase was quantified by measuring its dry weight, which was found to increase with increasing SC. The effect of colloids on DEHP sorption was studied by correcting the observed partition coefficients based on the concentration of colloid particles, and the true partition coefficients obtained (1.61 x 104 ± 1.29 x 103 ml g-1) were found to show much smaller variations than apparent partition coefficient (9.37 X 103 ± 2.12 x 103 ml g-1) at different SCs. Furthermore, the true organic carbon-normalised partition coefficients for the two sediments with different organic carbon content became similar and relatively independent of SCs. (C) 2000 Published by Elsevier Science B.V.
Zhou, JL, Hong, H, Zhang, Z, Maskaoui, K & Chen, W 2000, 'Multi-phase distribution of organic micropollutants in Xiamen Harbour, China', Water Research, vol. 34, no. 7, pp. 2132-2150.
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Xiamen Harbour, in the Xiamen Special Economic Zone of the People's Republic of China, was studied for its water and sediment quality, by determining the levels of 16 polycyclic aromatic hydrocarbons (PAHs), 12 polychlorinated biphenyls (PCBs) and 18 organochlorine insecticides in water, suspended particulate matter (SPM), pore water and sediment samples from nine stations in the Harbour. Total PAH concentrations varied from 106 to 945 ng/l in water, <1 to 3548 ng/l in pore water, and 247 to 480 ng/g dry weight in surficial sediments. Total PCB levels varied from 0.1 to 1.7 ng/l in water, 2.7 to 34.8 ng/l in pore water, and <0.01 to 0.32 ng/g dry weight in sediments. The levels of all insecticides were in the range of 6.6-19.6 ng/l (water), 11.8-78.5 ng/l (pore water), and <0.01-0.58 ng/g dry weight (sediment). The levels of total hexachlorocyclohexane (HCHs) in sediments varied from <0.01 to 0.14 ng/g dry weight, and those of total DDTs were in the range of <0.01-0.06 ng/g dry weight. The micropollutants were present in higher levels in pore water than in surface water, due possibly to higher concentrations of dissolved organic carbon or colloids with which the hydrophobic pollutants are strongly associated. Such a concentration gradient implies a potential flux of pollutants from sediment pore water to overlying water. The levels of pollutants in sediments are one to several orders of magnitude lower than those found in 1993, suggesting their decreased inputs in recent years in the form of fresh and less contaminated material and possible degradation over a period of time. Further work is needed to quantify the levels of these contaminants in suspended particulate matter, which are currently below the limits of detection. (C) 2000 Elsevier Science Ltd.
ZHU, XQ & LAW, SS 2000, 'IDENTIFICATION OF VEHICLE AXLE LOADS FROM BRIDGE DYNAMIC RESPONSES', Journal of Sound and Vibration, vol. 236, no. 4, pp. 705-724.
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Ball, JE 1970, 'Modelling pollutants in stormwater runoff', Hydro 2000 interactive hydrology : proceedings of the 3rd International Hydrology and Water Resources Symposium of the Institution of Engineers, The Institution of Engineers, Perth, Western Australia, pp. 1-6.
Ball, JE 1970, 'Parameter estimation for urban stormwater models', Hydro 2000 interactive hydrology : proceedings of the 3rd International Hydrology and Water Resources Symposium of the Institution of Engineers, Hydrology and Water Resources Symposium, The Institution of Engineers, Perth, Western Australia, pp. 1-6.
Ball, JE 1970, 'Runoff from road surfaces - how contaminated is it?', Hydro 2000 interactive hydrology : proceedings of the 3rd International Hydrology and Water Resources Symposium of the Institution of Engineers, Hydrology and Water Resources Symposium, Institution of Engineers, Australia, Perth, Western Australia, pp. 1-6.
Ball, JE & Cordery, I 1970, 'Information and hydrology', Hydro 2000 : 3rd International Hydrology and Water Resources Symposium of the Institution of Engineers, Australia, Institution of Engineers Australia, Perth, Australia, pp. 997-1001.
Castel, A, Francois, R & Arliguie, G 1970, 'Factors other than chloride level influencing corrosion rate of reinforcement', American Concrete Institute, ACI Special Publication, pp. 629-644.
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To evaluate the degree of corrosion, reinforcements of a fourteen-year-old concrete member were completely bared. The 3-meter long beams were stored in 3-point flexion in an aggressive environment made by sequences of drying and wetting by a salt fog (35g/l). The total chloride content was also measured at the level of all reinforcements. Because of the small concrete cover (10 mm for the stirrups and 16 mm for the longitudinal reinforcement), the chloride content appears to be significantly greater than the threshold usually used to evaluate the initiation of corrosion. Carbonation front was also measured and was only about 4 mm. Nevertheless, the degree of corrosion (mass loss calculation) shows no correlation with chloride content, as some large parts of reinforcement are not affected by corrosion. As a result, corrosion damage seems to be linked to a degradation of the steel-concrete interface. For tensile reinforcement, it corresponds to a mechanical degradation whereas for compression reinforcement it corresponds to the bleeding. This observation leads us to question ourselves about the relevance of a single value for the corrosion threshold. The nature of the interface between the steel and the concrete must be considered.
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.
Khatri, R, Sirivivatnanon, V & Marsh, P 1970, 'Importance of curing on chloride-induced corrosion', American Concrete Institute, ACI Special Publication, pp. 487-505.
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The effect of a range of curing regimes on the resistance to chloride penetration of concretes has been studied. Concretes with two binder systems namely normal portland cement (NPC) and a 30% fly ash blend (FA) were subjected to four different curings. They include 1-day sealed, 7-day sealed, 7-day wet and a simulated steam curing. Subsequent to each curing regime, the samples of grade 40 concretes were air cured in standard laboratory conditions until the age of 28-day before exposure to 15 cycles and 100 cycles of immersion in 3% NaCl solution and drying. Resistance to chloride ion penetration was evaluated by examining both the chloride profile and diffusion coefficient (calculated by Fick's second law). Thus the role of curing in governing the resistance of concrete to chloride ion penetration was established. NPC concrete was found to be more sensitive to the type of curing than the fly ash concrete. NPC concrete subjected to 1-day and 7-day sealed curing resulted in lower chloride penetration resistance than the 7-day wet curing. However, the fly ash concrete showed remarkable tolerance to the lack of moist curing giving very similar performance in both 1-day and 7-day sealed curing as the 7-day wet curing. Steam curing resulted in poorer resistance to chloride penetration for both concretes. For each type of curing, the fly ash concretes gave significantly better resistance to chloride penetration than the NPC concrete (of similar grade). Effect of curing on sorptivity and volume of permeable voids (Vpv) of concretes of grades 20, 40 and 50 were also studied. Both sorptivity and Vpvwere found to be influenced by the type of curing for both binders. Vpvwas found to show correlation to the long-term chloride penetration resistance of the concrete. No such correlation was found for sorptivity values.
Law, SS, Howe, D & Zhu, XQ 1970, 'Modal strain energy change in neural network damage assessment', ADVANCES IN STRUCTURAL DYNAMICS, VOLS I & II, International Conference on Advances in Structural Dynamics (ASD 2000), ELSEVIER SCIENCE BV, HONG KONG, PEOPLES R CHINA, pp. 1037-1044.
Masjuki, HH, Mahlia, TMI, Choudhury, IA & Saidur, R 1970, 'A literature review on energy efficiency standards and labels for household electrical appliances', 2000 TENCON Proceedings. Intelligent Systems and Technologies for the New Millennium (Cat. No.00CH37119), 2000 TENCON Proceedings. Intelligent Systems and Technologies for the New Millennium, IEEE, KUALA LUMPUR, MALAYSIA, pp. A103-A107.
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Masjuki, HH, Saidur, R, Choudhury, IA & Mahlia, TMI 1970, 'Factors effecting energy consumption of household refrigerator-freezers', 2000 TENCON Proceedings. Intelligent Systems and Technologies for the New Millennium (Cat. No.00CH37119), 2000 TENCON Proceedings. Intelligent Systems and Technologies for the New Millennium, IEEE, KUALA LUMPUR, MALAYSIA, pp. A92-A96.
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Ngo, HH, Vigneswaran, S, Kim, SH, Bidkar, A & Moon, H 1970, 'Microfiltration-adsorption hybrid system in organics removal from water', Water Science and Technology, 2nd International Conference on Membrane Technology in Environmental Management, I W A PUBLISHING, TOKYO, JAPAN, pp. 51-57.
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A series of experiments was conducted with a Millipore flat plate microfiltration module modified to incorporate in-line powdered activated carbon (PAC) addition In-line PAC was mixed continuously through a spiral mixing device for a predetermined time prior entering a membrane unit. The results showed that this system is excellent in removing fulvic acid (FA). This system provides to sufficient contact time for PAC to adsorb organics compared to the system with in-line adsorbent addition. More than 85% of FA was removed from water containing 8 mg/l of FA. To achieve this following conditions were used:.(i) a velocity gradient G (mixing intensity) of 160.4 s-1; (ii) a hydraulic residence time (mixing time) of 4 minutes; (iii) a PAC dose of 260 mg/l; and (iv) membrane pore size of 0.22 μm. In case of low FA concentration (e.g. 1.2 mg/l) in water, the removal efficiency was almost 100%. The removal efficiency also increased with the increase of mixing intensity and mixing timer. The permeate flux slightly improved when a membrane of pore size 0.22 μm was used with shorter hydraulic residence time and lower PAC concentration. This paper presents a mathematical model developed based on surface diffusion. The model successfully predicted the performance of this hybrid system.
Stewart, MG 1970, 'Optimization of Durability Design Specifications for RC Structures', Advanced Technology in Structural Engineering, Structures Congress 2000, American Society of Civil Engineers.
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A structural deterioration life-cycle reliability model is used herein to calculate probabilities of cracking and spalling for typical RC structures. The influence of mix composition (water-cement ratio, concrete compressive strength) and cover on corrosion rates are included in the analysis. Life-cycle costs are estimated using time-dependent probabilities of failure calculated for annual increments over the lifetime of the structure (100 years). It was found that reducing the cover from that currently specified for design results in a significant increase in life-cycle costs. Copyright 2004 ASCE.
Umakhanthan, K & Ball, JE 1970, 'The influence of spatially variable rainfall on runoff hydrographs', Proc. Twelfth Congress of Asia Pacific Division of ADP-IAHR, Twelfth Congress of Asia Pacific Division of ADP-IAHR, GTrade Limited Partnership, Bangkok, Thailand, pp. 817-827.
Vigneswaran, S, Kwon, DY, Ngo, HH & Hu, JY 1970, 'Improvement of microfiltration performance in water treatment: is critical flux a viable solution?', Water Science and Technology, 2nd International Conference on Membrane Technology in Environmental Management, IWA Publishing, TOKYO, JAPAN, pp. 309-315.
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In this study, three definitions for critical flux were introduced based on the crossflow microfiltration (CFMF) experiments conducted under an operational mode of constant permeate flux. The critical flux based on material balance was calculated from the rate of particles deposition. The highest permeate flux results in no particle deposition being taken at the critical flux. The second definition was based on the increase in transmembrane pressure (TMP). The critical flux based on the TMP increase is the flux below which the membrane fouling does not occur. The third definition was based on the direct observation of particles deposition through microscope. Detailed experiments were conducted with synthetic suspension of different sizes of latex particles. Long term experiments conducted with polydispersed kaolin clay suspension indicated that the critical flux based on material balance concept is more realistic in field conditions.
Zhu, XQ & Law, SS 1970, 'Moving load identification using a time domain technique', ADVANCES IN STRUCTURAL DYNAMICS, VOLS I & II, International Conference on Advances in Structural Dynamics (ASD 2000), ELSEVIER SCIENCE BV, HONG KONG, PEOPLES R CHINA, pp. 601-608.
