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Full-Text Articles in Engineering
Unsaturated Drainage Layers For Diversion Of Infiltrating Water, J. C. Stormont, C. E. Morris
Unsaturated Drainage Layers For Diversion Of Infiltrating Water, J. C. Stormont, C. E. Morris
Faculty of Engineering - Papers (Archive)
An approach for draining water from unsaturated soil is presented that utilizes a sloping system of a fine sand overlying a coarser sand or gravel. In this configuration, referred to as an unsaturated drainage layer, the sand laterally drains water that accumulates above the capillary break provided by the coarse material. Drainage capacity is maximized when the sand layer has sufficient moisture to be relatively conductive, yet remains unsaturated so as to prevent failure of the capillary break. Results from field tests indicate substantial downward infiltrating water can be laterally diverted with an unsaturated drainage layer. Numerical simulations are presented …
Light Scattering From A Periodically Modulated Two-Dimensional Electron Gas With Partially Filled Landau Levels , A. Brataas, C. Zhang, K. A. Chao
Light Scattering From A Periodically Modulated Two-Dimensional Electron Gas With Partially Filled Landau Levels , A. Brataas, C. Zhang, K. A. Chao
Faculty of Engineering - Papers (Archive)
We study light scattering from a periodically modulated two-dimensional electron gas in a perpendicular magnetic field. If a subband is partially filled, the imaginary part of the dielectric function as a function of frequency contains additional discontinuities to the case of completely filled subbands. The positions of the discontinuities may be determined from the partial filling factor and the height of the discontinuity can be directly related to the modulation potential. The light-scattering cross section contains a peak which is absent for integer filling.
Plane-Strain Modeling Of Smear Effects Associated With Vertical Drains, Buddhima Indraratna, I. W. Redana
Plane-Strain Modeling Of Smear Effects Associated With Vertical Drains, Buddhima Indraratna, I. W. Redana
Faculty of Engineering - Papers (Archive)
The present study provides a methodology to include the smear effect of vertical drains in a two-dimensional (2D) plane-strain finite-element model, employing the modified Cam-clay theory. The analysis is conducted by converting the radius of the smear zone and its permeability (axisymmetric) into equivalent plane strain parameters. The introduction of smear effects improves the accuracy of the numerical model that is tested for a Malaysian soft clay, in this study.
Compression And Degradation Of Railway Ballast Under One-Dimensional Loading, Buddhima Indraratna, D. Ionescu, D. Christie, R. Chowdhury
Compression And Degradation Of Railway Ballast Under One-Dimensional Loading, Buddhima Indraratna, D. Ionescu, D. Christie, R. Chowdhury
Faculty of Engineering - Papers (Archive)
The rate at which railway track geometry deteriorates is greatly influenced by the behaviour of ballast. This paper presents the findings of a series of one-dimensional compression tests on latite ballast used by the State Rail Authority of New South Wales in the construction of railway tracks. These tests are part of an extended research program designed to thoroughly study the stress-strain relationships, failure properties and degredation characteristics of various types of railway ballast.
Nonlinear Transport In Steady-State Terahertz-Driven Two-Dimensional Electron Gases, W. Xu, C. Zhang
Nonlinear Transport In Steady-State Terahertz-Driven Two-Dimensional Electron Gases, W. Xu, C. Zhang
Faculty of Engineering - Papers (Archive)
We present a detailed theoretical study on nonlinear transport and optical properties in two-dimensional semiconductor systems (2DSS's) subjected to intense terahertz electromagnetic fields. By solving the momentum- and energy-balance equations using a steady-state Boltzmann equation approach, where electron interaction with LO phonons is taken into account under the lowest-order approximation for GaAs-based 2DSS"s, we have investigated the dependence of electron temperature, momentum relaxation time, and conductivity on the intensity and frequency of THz radiation fields. The results obtained from this study are in line with those obtained from recent experimental measurements
Anomalous Magnetization Peak Effect In Spiral-Grown Bi2sr2cacu2oy Crystals, Xiaolin Wang, J. Horvat, Hua-Kun Liu, J. N. Li, S. X. Dou
Anomalous Magnetization Peak Effect In Spiral-Grown Bi2sr2cacu2oy Crystals, Xiaolin Wang, J. Horvat, Hua-Kun Liu, J. N. Li, S. X. Dou
Faculty of Engineering - Papers (Archive)
Magnetic hysteresis loops were measured on spiral-grown Bi2Sr2CaCu2Oy (Bi-2212) crystals. An anomalous peak effect at a magnetic field of 1000–2000 Oe was observed both in high-Tc (86 K) and oxygen underdoped (Tc=76 K) spiral-grown crystals between 20 and 40 K. The peak effect was observed to be stronger than that induced by oxygen vacancies, defect dislocation networks reported in Bi-2212 crystals. Further, the anomalous peak almost completely disappeared after removing growth spiral patterns from the crystal surface. Edge barriers associated with the growth spirals are suggested to be responsible for the strong peak effect for the spiral-grown Bi-2212 crystals and …
Irreversible Critical Current And The Anomalous Magnetic-Moment Peak In Silver-Sheathed (Pb,Bi)2sr2ca2cu3o10 + Y Tapes, K. H. Muller, C. Andrikidis, Y. C. Guo
Irreversible Critical Current And The Anomalous Magnetic-Moment Peak In Silver-Sheathed (Pb,Bi)2sr2ca2cu3o10 + Y Tapes, K. H. Muller, C. Andrikidis, Y. C. Guo
Faculty of Engineering - Papers (Archive)
We have measured under zero-field-cooled ZFC and field-cooled FC conditions the magnetic moments of a high-quality Pb,Bi2Sr2Ca2Cu3O10y tape at 5 K in perpendicular applied fields up to 1 T using a superconducting quantum interference device magnetometer. The intergranular magnetic moment, obtained by subtracting from the total magnetic moment the intragranular moment of the ''bent'' tape shows a pronounced anomalous peak at a positive field Hp . To interpret the experimental data the critical-state model for a flat superconducting strip in a perpendicular field is employed. The model includes the field dependence of the intergranular critical current density in first order. …
The Microscopic Nonequilibrium Process In Solids Under Transient Heating, B L. Zhou, G H. He, Y J. Gao, W L. Zhao, J D. Guo
The Microscopic Nonequilibrium Process In Solids Under Transient Heating, B L. Zhou, G H. He, Y J. Gao, W L. Zhao, J D. Guo
Faculty of Engineering - Papers (Archive)
A brief review of studies on tile dynamic process of thernml expansion since tile eighties is given. A magnitude of dill'crcnce of one to two orders between the restllts of theoretical calculations and experimental observations of tile characteristic time is discussed. Tile noneqtiilibritnn localized phonon gas in a "'hot spot" is studied using tile Bohzmann equation, leading to a soliton-like solution. It gives tile way to fill the gap of the above-mentioned difference between theory and experiment. Tile lattice relaxation of a laser rod is developed theoretically and verilied experimentally. Different expansion processes of a high-T~ superconductor below and above …
De Filtration To Remove Cryptosporidium, Jerry E. Ongerth, Primrose E. Hutton
De Filtration To Remove Cryptosporidium, Jerry E. Ongerth, Primrose E. Hutton
Faculty of Engineering and Information Sciences - Papers: Part A
Laboratory-scale testing investigated the degree of Cryptosporidium oocyst reduction provided by diatomaceous earth (DE) filtration. Three grades of DE from two manufacturers were used in the tests. Reduction was measured using seeded river water applied to Walton test filters. Tests were run for filtration rates of 1 and 2 gpm/sq ft (2.4 and 4.9 m/h). Each run was replicated three times, and quality control was rigorous. Approximately 6 logs of reduction in the concentration of Cryptosporidium oocysts can be expected under routine operating conditions using DE grades having permeability of <1.2 Darcy. Log reductions varied predictably according to the permeability of the DE grade and the filtration rate; they were significantly higher at the higher filtration rate. Agreement was excellent between runs, enabling researchers to distinguish with consistent statistical significance the differences in performance.
Risk Assessment Of Sloping Land Using Gis-Based Mapping, Phil N. Flentje, Robin N. Chowdhury
Risk Assessment Of Sloping Land Using Gis-Based Mapping, Phil N. Flentje, Robin N. Chowdhury
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, attention is drawn to GIS-based techniques for mapping and risk assessment for slopes and landslides. The authors focus on an approach developed recently for mapping of geology and slope stability in the Northern Illawarra (or the Northern Suburbs of Greater Wollongong Area) in New South Wales, Australia. The use of databases of geology and land instability and use of other GIS-based information relevant to sloping land for the development of a valid hazard and risk assessment procedure is explored. The developed approach will be applicable to other sloping areas and, in particular, urban areas both nationally and …
The Impact Of Ios-Enabled Business Process Change On Business Outcomes: Transformation Of The Value Chain Of Japan Airlines, Akemi Chatfield, Niels Bjorn-Andersen
The Impact Of Ios-Enabled Business Process Change On Business Outcomes: Transformation Of The Value Chain Of Japan Airlines, Akemi Chatfield, Niels Bjorn-Andersen
Faculty of Engineering and Information Sciences - Papers: Part A
We present a framework for evaluating the impact of IT-enabled radical process change on business outcomes at Japan Airlines. The framework presents a systemic view of factors that are shown to impact the firm's business outcomes. The framework identifies salient global environmental factors and business challenges the firm faces, strategic responses it makes, and management methodologies and strategic IT systems adopted to enable the firm's changes in business processes. We then discuss the radical transformation of the traditional keiretsu-based value chain at Japan Airlines, the world's third largest airline company. We apply the framework to evaluate the impact of the …
Capillary Barriers And Subtitle D Covers: Estimating Equivalency, C. E. Morris, J. C. Stormont
Capillary Barriers And Subtitle D Covers: Estimating Equivalency, C. E. Morris, J. C. Stormont
Faculty of Engineering - Papers (Archive)
Accumulating data on traditional compacted soil-surface covers are demonstrating that they are likely to degrade and have reduced effectiveness as long-term barriers; therefore, suitable alternatives are being examined. One possible alternative that is receiving increased attention is capillary barriers. The U.S. Environmental Protection Agency (USEPA) allows for alternatives to be used, but requires that they achieve infiltration and erosion protection equivalent to that of designs contained in design guidance documents. A method of comparing a capillary barrier to a design that features a compacted soil layer that meets the minimum requirements for a solid-waste landfill cover (so-called Subtitle D) under …
Computer Control Of Machines With Friction For Precise Motion, Simon Webb, Zheng Li, Christopher David Cook
Computer Control Of Machines With Friction For Precise Motion, Simon Webb, Zheng Li, Christopher David Cook
Faculty of Engineering - Papers (Archive)
We study the problem of precise control of machines with static and Coulomb friction. An experimental X-Y testbed built for testing various control methods is described and initial experimental results are presented. A simple pole placement controller is designed for computer control of the X-Y testbed based on a generalised sampled-data hold. Robustness and stability of the controller are analysed. Simulation suggests that this controller is able to achieve precise position control even when parameters of both the dynamics of the machine and the characteristics of friction are unknown