Engineering Commons^™

Silicon Microdosimetry In Heterogeneous Materials: Simulation And Experiment, A. Wroe, Anatoly B. Rosenfeld, I. Cornelius, Dale A. Prokopovich, M. Reinhard, R. Schulte, V. Bashkirov

Faculty of Engineering - Papers (Archive)

Microdosimetry spectra obtained experimentally utilizing a Silicon-On-Insulator (SOI) microdosimeter within biological materials, was used to provide information on secondary radiation spectra at tissue boundaries. Comparative GEANT4 simulations of the experimental conditions were also conducted.

Human Behaviour Recognition With Segmented Inertial Data, Chao Sun, David A. Stirling, Fazel Naghdy

Faculty of Engineering - Papers (Archive)

The development and recent advancements of integrated inertial sensors has afforded substantive new possibilities for the acquisition and study of complex human motor skills and ultimately their imitation within robotic systems. This paper describes continuing work on kinetic models that are derived through unsupervised learning from a continuous stream of signals, including Euler angles and accelerations in three spatial dimensions, acquired from motions of a human arm. An intrinsic classification algorithm, MML (Minimum Message Length encoding) is used to segment the complex data, formulating a Gaussian Mixture Model of the dynamic modes it represents. Subsequent representation and analysis as FSM …

Numerical Prediction Of Vadose Zone Behaviour Influenced By Vegetation, Buddhima Indraratna, Behzad Fatahi, Mohammad Hadi Khabbaz

Faculty of Engineering - Papers (Archive)

Bioengineering aspects of native vegetation are currently, and rapidly, being evolved to improve soil stiffness, slope stabilisation, and erosion control. Apart from the reinforcement effect, tree roots establish sufficient matric suction to increase the shear strength and stiffness of the soil. This paper looks at the way, vegetation influences soil matric suction, shrinkage, and ground settlement. A mathematical model for the rate of root water uptake that considers ground conditions, type of vegetation and climatic parameters, has been developed. Based on this proposed model, the distribution of moisture and the matric suction profile adjacent to the tree are numerically analysed. …

Special Class Of Positive Definite Functions For Formulating Adaptive Micro/Nano Manipulator Control, Hwee Choo Liaw, Denny Oetomo, Gursel Alici, Bijan Shirinzadeh

Faculty of Engineering - Papers (Archive)

This paper presents a special class of positive definite functions for the formulation of adaptive control strategies, specifically in the research of an effective control algorithm for piezoelectric actuation systems in micro/nano manipulation. To deal with the control problems of unknown system parameters, nonlinear hysteresis effects, and disturbances in the piezoelectric actuation systems, an adaptive control methodology is proposed. Using the saturation function derived from a positive definite function to formulate the control methodology, the closed-loop system stability can be guaranteed. Furthermore, the control methodology is proposed to track a desired motion trajectory in position, velocity, and acceleration. In this …

Surprising Shrinkage Of Expanding Gels Under An External Load, Seon Jeong Kim, Geoffrey M. Spinks, Shona Prosser, Philip G. Whitten, G G. Wallace, Sun I. Kim

Faculty of Engineering - Papers (Archive)

Hydrogels are fascinating and useful in that they can show large volume changes in response to various stimuli, such as temperature or chemical environment. Here we report the peculiar observation that chemically crosslinked hydrogels that normally expand owing to a change in electrolyte pH can be made to shrink in certain circumstances. Specifically, these hydrogels contract when tested at a constant compressive force and subjected to a pH change that causes expansion in the absence of the applied load. When tested under tension, the gels always expand. Although the effects of external stress on the swelling of gels is known, …

Fiber-Optic Temperature Sensor Based On Interference Of Selective Higher-Order Modes, Enbang Li, X L Wang, Chao Zhang

Faculty of Engineering - Papers (Archive)

A fiber-optic temperature sensor based on the interference of selective higher-order modes in circular optical fibers is described. The authors demonstrate that by coupling the LP01 mode in a standard single-mode fiber to the LP0m modes in a multimode fiber, and utilizing the interference of the higher-order modes, a fiber-optic temperature sensor which has an extremely simple structure and is suitable for high-temperature measurements can be constructed. The sensing principle, temperature measurement experiments, and results are presented.

Nature Of Subpicosecond Terahertz Pulse Propagation In Practical Dielectric-Filled Parallel-Plate Waveguides, Rajind Mendis

Faculty of Engineering - Papers (Archive)

It is analytically shown that the presence of submicrometer-sized air gaps between the dielectric and metal contact surfaces in a dielectric-filled metallic parallel-plate waveguide can have a dramatic effect on the guided-wave propagation of subpicosecond terahertz pulses. Through the use of metal-evaporated dielectric surfaces to overcome the imperfect contact problem, and a special air-dielectric-air cascaded waveguide geometry to avoid multimode excitation, undistorted subpicosecond terahertz pulse propagation via the single-TEM mode is demonstrated, for what is believed to be the first time, in a silicon-filled PPWG.

Assessment Of The Structural Development Of Resin Bonded Taphole Clay (Icsti 06), Sharon Nightingale, Lisa Wells, F W B U Tanzil, Jim Cummins, Brian J. Monaghan, K Price

Faculty of Engineering - Papers (Archive)

Resin in taphole clay provides good extrudability and strength at low temperatures. However, it also contains volatile matter that is lost on heating. The blast furnace taphole is subject to a large thermal gradient, leading to variation in the bonding and structure of the clay along the taphole’s length. This has a critical effect on properties. Effects of this variation in properties on furnace operations are not well understood. A simple laboratory test was devised to simulate the thermal gradient, and assess its effects on taphole clays.

Thermogravimetric tests were also conducted at different heating rates. Results of experiments are …

Modelling Solids Friction Factor For Dense-Phase Pneumatic Conveying Of Powders, Peter W. Wypych, David B. Hastie

Faculty of Engineering - Papers (Archive)

This paper presents results from an investigation into power-function modelling of solids friction factor for the dilute-phase and fluidised dense-phase (FDP) conveying of powders. Three different diameters/lengths of pipeline were used to generate a wide range of steady-state data and also explore important scale-up issues. The effect of pressure tapping locations on the data and derived models was also investigated. Different sets of power-function model solutions were used for comparison purposes and also to check scale-up stability and accuracy. Comparisons with predictions from recent models developed by other researchers are included. It is concluded that certain forms of the power …

Thermal Stability And Crystallization Kinetics Of Mechanically Alloyed Tic/Ti-Based Metallic Glass Matrix Composite, Laichang Zhang, J. Xu, J Eckert

Faculty of Engineering - Papers (Archive)

A Ti-based metallic glass matrix composite with 10vol% TiC is synthesized by mechanical alloying. The thermal stability and crystallization kinetics of the metallic glass and compositepowders are investigated by differential scanning calorimetry in the mode of isochronal heating and isothermal annealing. The isothermal transformation kinetics is analyzed by the Kolmogorov-Johnson-Mehl-Avrami equation. The values of the Avrami exponent calculated for low crystallization volume fractions imply that the crystallization of both types of powders is governed by diffusion-controlled three-dimensional growth. The mean activation energy of crystallization for the composite is slightly lower than that of the Ti-based metallic glass. The addition of …

Chemical Modification Of Precursor Solution For Long Length Ybco Coated Conductor Fabrication, Jaimoo Yoo, Young-Kuk Kim, Kookchae Chung, Jaewoong Ko, Gye-Won Hong, Hee-Gyoun Lee, Jin-Heung Kim, Hyungsik Chung, X. L. Wang, S. X. Dou

Faculty of Engineering - Papers (Archive)

Long length MOD processing of YBCO conductor requires high performance precursor solution without degradation during the process. In this study, effect of chemical modification of precursor solution on MOD processing was investigated to meet the requirement. Highly stable YBCO precursor solution was synthesized with PVP (polyvinylpyrrolidone) and crack-free thick precursor film was successfully fabricated. However, annealed YBCO film shows porous microstructures originated from large HF gas generation from thick films and residual carbon from additives. Reduction of fluorine content is required to densify microstructures. In order to reduce fluorine content, F-free Cu-precursor solution was synthesized. YBCO film with J_{c …}

A New Model For Thermal Conductivity In Nanofluids, Pei Tillman, James M. Hill

Faculty of Engineering - Papers (Archive)

Nanofluids exhibit enhanced thermal conductivity superior to traditional heat transfer fluids. The conventional theoretical models cannot explain the large enhancement of the thermal conductivity of nanofluids. It has been proposed that an interfacial structure formed by liquid molecular layering might play an important role. To date there is no known procedure to properly calculate the nanolayer thickness, and all previous investigators arbitrarily adopt a layer thickness which is consistent with experimental results. Here we investigate the thermal conductivity structure of this interfacial layer and its impact on the effective thermal conductivity and an expression for the thermal conductivity profile in …

Providing A Context For First Year Engineering Students: A Report On Attempts At Course Inversion, Richard A. Dwight, Timothy J. Mccarthy, Anna L. Carew, Brian Ferry

Faculty of Engineering - Papers (Archive)

Observations of how engineering students approach learning activities in the earlier years of their degree, report that they do not recognise real-life context that links to the theory they are required to apply in learning tasks. This impacts on their motivation and contributes to a lack of transfer of basic knowledge in the latter years of their degree. A new subject for first year engineering students was introduced at the University of Wollongong in 2005 focusing on real-life engineering problems requiring analysis for effective solution. Students are encouraged to explore the use of basic principles and available analysis techniques relevant …