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Faculty of Engineering - Papers (Archive)

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Full-Text Articles in Engineering

Effect Of Eccentric Load On Retrofitted Reinforced Concrete Columns Confined With Frp, Thong M. Pham, X Lei, Muhammad N. S Hadi Jan 2013

Effect Of Eccentric Load On Retrofitted Reinforced Concrete Columns Confined With Frp, Thong M. Pham, X Lei, Muhammad N. S Hadi

Faculty of Engineering - Papers (Archive)

Different behaviour of diverse sections of confined Reinforced Concrete (RC) columns under eccentric load is investigated in this study. Three types of sections are considered, which include square columns, square with rounded corners and modified circular columns. Twelve reinforced square concrete columns were made from normal strength concrete and subdivided into four groups. The first three columns were the Reference Group and had no modification.The next three columnswere modified with round corners and wrapped with three layers of Carbon Fibre Reinforced Polymer (CFRP), another three were bonded with four pieces of segmental circular concrete covers and wrapped with three layers …


Effects Of Membrane Fouling On N-Nitrosamine Rejection By Nanofiltration And Reverse Osmosis Membranes, Takahiro Fujioka, Stuart J. Khan, James A. Mcdonald, Rita K. Henderson, Yvan Poussade, Jorg E. Drewes, Long Nghiem Jan 2013

Effects Of Membrane Fouling On N-Nitrosamine Rejection By Nanofiltration And Reverse Osmosis Membranes, Takahiro Fujioka, Stuart J. Khan, James A. Mcdonald, Rita K. Henderson, Yvan Poussade, Jorg E. Drewes, Long Nghiem

Faculty of Engineering - Papers (Archive)

The impact of fouling on N-nitrosamine rejection by nanofiltration (NF) and reverse osmosis (RO) membranes was investigated in this study. Membrane fouling was simulated using tertiary treated effluent and several model fouling solutions (that contained sodium alginate, bovine serum albumin, humic acid or colloidal silica) to elucidate the changes in rejection behaviour of N-nitrosamines. In general, the rejection of N-nitrosamines increased when the membranes were fouled by tertiary effluent. The rejection of small molecular weight N-nitrosamines was most affected by membrane fouling. In particular, the rejection of N-nitrosodimethylamine (NDMA) by the ESPA2 membrane increased from 34 to 73% after membrane …


Effect Of Ply Configuration On Hollow Square Reinforced Concrete Columns Confined With Carbon Fibre-Reinforced Polymer (Cfrp), T D. Le, M T. Lester, Muhammad N. S Hadi Jan 2013

Effect Of Ply Configuration On Hollow Square Reinforced Concrete Columns Confined With Carbon Fibre-Reinforced Polymer (Cfrp), T D. Le, M T. Lester, Muhammad N. S Hadi

Faculty of Engineering - Papers (Archive)

This paper presents results of testing twelve hollow square reinforced concrete specimens wrapped with Carbon fibre reinforced polymer CFRP. The effect of ply configuration on the behaviour of the specimens is investigated. All specimens were 800mm high and had the dimensions of 200mm×200mm in cross-section and a hollow core of 80mm×80 mm. The specimens were divided into four groups with three specimens each. The specimens in the first group without bonding CFRP served as references. While the remaining three groups of specimens were externally wrapped with CFRP in three different ply configurations of hoop, vertical and 45◦ angle with reference …


Stabilization Of Nazn(Bh4)3 Via Nanoconfinement In Sba-15 Towards Enhanced Hydrogen Release, Guanglin Xia, Li Li, Zaiping Guo, Qinfen Gu, Yanhui Guo, Xuebin Yu, Hua-Kun Liu, Zongwen Liu Jan 2013

Stabilization Of Nazn(Bh4)3 Via Nanoconfinement In Sba-15 Towards Enhanced Hydrogen Release, Guanglin Xia, Li Li, Zaiping Guo, Qinfen Gu, Yanhui Guo, Xuebin Yu, Hua-Kun Liu, Zongwen Liu

Faculty of Engineering - Papers (Archive)

In the present work, the decomposition behaviour of NaZn(BH4)3 nanoconfined in mesoporous SBA-15 has been investigated in detail and compared to bulk NaZn(BH4)3 that was ball milled with SBA-15, but not nanoconfined. The successful incorporation of nanoconfined NaZn(BH4)3 into mesopores of SBA-15 was confirmed by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, 11B nuclear magnetic resonance, nitrogen absorption/desorption isotherms, and Fourier transform infrared spectroscopy measurements. It is demonstrated that the dehydrogenation of the space-confined NaZn(BH4)3 is free of emission of boric by-products, and significantly improved hydrogen release kinetics is also achieved, with pure hydrogen release at temperatures …


An Elasto-Plastic Model For Liquefiable Sands Subjected To Torsional Shear Loadings, Gabriele Chiaro, Junichi Koseki, Nalin L. I De Silva Jan 2013

An Elasto-Plastic Model For Liquefiable Sands Subjected To Torsional Shear Loadings, Gabriele Chiaro, Junichi Koseki, Nalin L. I De Silva

Faculty of Engineering - Papers (Archive)

This paper presents a modeling procedure for simulating the monotonic undrained torsional shear behavior of sands, including stress-strain relationship, and excess pore water pressure generation, while considering the void ratio and stress level dependence of stress-strain-dilatancy behavior of sand. A unique set of soil parameters is required by the model to satisfactorily predict the undrained behavior of loose and dense Toyoura sand over a wide range of initial void ratios and confining pressures, as proven by simulating experimental data produced by the authors and found in the literature.


Influence Of Ti/N Ratio On Simulated Cghaz Microstructure And Toughness In X70 Steels, Z X. Zhu, M Marimuthu, L Kuzmikova, H J. Li, F Barbaro, L Zheng, M Z. Bai, C Jones Jan 2013

Influence Of Ti/N Ratio On Simulated Cghaz Microstructure And Toughness In X70 Steels, Z X. Zhu, M Marimuthu, L Kuzmikova, H J. Li, F Barbaro, L Zheng, M Z. Bai, C Jones

Faculty of Engineering - Papers (Archive)

Three API 5L X70 steels with different Ti and N contents and otherwise identical chemistry were selected to investigate the effect of Ti/N ratio on the toughness in coarse grained heat affected zone (CGHAZ). A Gleeble 3500 thermomechanical simulator was used to simulate the thermal profile of CGHAZ of double submerged arc welding process. The microstructure was examined by optical microscopy. Statistics of CGHAZ grain coarsening were compiled by measuring the prior austenite grain size. Toughness of the simulated CGHAZ regions was evaluated by Charpy V-notch testing at -20 and -40°C. Morphology of the impact fracture surface was investigated using …


Microstructure Evolution And Alloying Elements Distribution Between The Phases In Powder Near-B Titanium Alloys During Thermo-Mechanical Processing, Mansur Ahmed, Azdiar A. Gazder, Dmytro G. Savvakin, Orest M. Ivasishin, E V. Pereloma Jun 2012

Microstructure Evolution And Alloying Elements Distribution Between The Phases In Powder Near-B Titanium Alloys During Thermo-Mechanical Processing, Mansur Ahmed, Azdiar A. Gazder, Dmytro G. Savvakin, Orest M. Ivasishin, E V. Pereloma

Faculty of Engineering - Papers (Archive)

In the present study, two powders near-β Ti alloys having a nominal composition of Ti-5Al-5Mo-5V-XCr-1Fe (X = 1–2, wt%) were studied. The alloys were produced via the blended elemental powder metallurgy technique using hydrogenated Ti powder. Microstructure evolution and the distribution of the alloying elements between the phases were investigated after each step of thermo-mechanical processing (TMP). Microstructures were refined through the TMP in both alloys. Porosity was reduced with deformation at 1173 K (900 °C) in the β phase field. The β → α phase transformation occurred during soaking at 1023 K (750 °C) in the α + β …


Development Of Reliability-Based Design For Railway Prestressed Concrete Sleepers, Sakdirat Kaewunruen, Alexander Remennikov, Martin H. Murray May 2012

Development Of Reliability-Based Design For Railway Prestressed Concrete Sleepers, Sakdirat Kaewunruen, Alexander Remennikov, Martin H. Murray

Faculty of Engineering - Papers (Archive)

Faster and heavier train services are a driven improvement aspect for leaner and more profitable transport logistics of either passengers or freights. Ballasted rail track has been adopted for modern railways because of its many superior advantages in design, construction, short- and long-term maintenance, sustainability, financial capital and life cycle cost. An important element of the railway track system, which distributes the wheel load to the formation and holds the rail gauge, is the railway sleeper. Field data has raised concerns about design techniques for prestressed concrete (PC) sleepers. Most current design codes for these rely on allowable stresses and …


Effect Of A Static Magnetic Field On Nanodosimetric Quantities In A Dna Volume, Peter Lazarakis, Marion U. Bug, Elisabetta Gargioni, Susanna Guatelli, Sabastien Incerti, Hans Rabus, Anatoly B. Rosenfeld Jan 2012

Effect Of A Static Magnetic Field On Nanodosimetric Quantities In A Dna Volume, Peter Lazarakis, Marion U. Bug, Elisabetta Gargioni, Susanna Guatelli, Sabastien Incerti, Hans Rabus, Anatoly B. Rosenfeld

Faculty of Engineering - Papers (Archive)

Abstract Purpose: With the advent of magnetic resonance imaging (MRI)-guided radiation therapy it is becoming increasingly important to consider the potential influence of a magnetic field on ionising radiation. This paper aims to study the effect of a magnetic field on the track structure of radiation to determine if the biological effectiveness may be altered. Methods: Using the Geant4-DNA (GEometry ANd Tracking 4) Monte Carlo simulation toolkit, nanodosimetric track structure parameters were calculated for electrons, protons and alpha particles moving in transverse magnetic fields up to 10 Tesla. Applying the model proposed by Garty et al., the track structure parameters …


Application Of A Gac-Coated Hollow Fiber Module To Couple Enzymatic Degradation Of Dye On Membrane To Whole Cell Biodegradation Within A Membrane Bioreactor, Faisal I. Hai, Kazuo Yamamoto, Fumiyuki Nakajima, Kensuke Fukushi Jan 2012

Application Of A Gac-Coated Hollow Fiber Module To Couple Enzymatic Degradation Of Dye On Membrane To Whole Cell Biodegradation Within A Membrane Bioreactor, Faisal I. Hai, Kazuo Yamamoto, Fumiyuki Nakajima, Kensuke Fukushi

Faculty of Engineering - Papers (Archive)

Additional granular activated carbon (GAC) layers on the membrane module within a whole cell fungal membrane bioreactor (MBR) set up to treat dye wastewater was effective in minimizing enzymewashout and in improvement of decoloration (degradation of the dye). Supporting batch tests and continuous monitoring of the quality of bioreactor-supernatant and membrane-penneate revealed that biodegradation was effected by both the suspended culture and the dynamically immobilized enzyme on the GAC-coated membrane. In a control MBR. the efficiency of dye removal was variable; in contrast. 85% to near complete removal of dye was achieved using the MBRs equipped with a membrane with …


Use Of The Soil Modulus For Compaction Control Of Compacted Soils, Ana Heitor, Buddhima Indraratna, Cholachat Rujikiatkamjorn Jan 2012

Use Of The Soil Modulus For Compaction Control Of Compacted Soils, Ana Heitor, Buddhima Indraratna, Cholachat Rujikiatkamjorn

Faculty of Engineering - Papers (Archive)

Insufficient compaction conditions can cause significant roadway infrastructure maintenance costs. Conventional compaction control, using nuclear methods, is based on the discrete in situ determination of the dry density and moisture content. Recently, there has been an increase interest in alternative methods for compaction control using intelligent compaction technologies. This method enables the continuous measurement of the soil modulus and the degree of compaction on the layer that is being compacted. Thus, the efficiency of the compaction process can be maximized. Although the adoption of this method is very promising, it constitutes a change of project specification for the contractors (i.e. …


Experimental Realization Of Superconducting Quantum Interference Devices With Topological Insulator Junctions, M Veldhorst, C G. Molenaar, Xiaolin Wang, H Hilgenkamp, A Brinkman Jan 2012

Experimental Realization Of Superconducting Quantum Interference Devices With Topological Insulator Junctions, M Veldhorst, C G. Molenaar, Xiaolin Wang, H Hilgenkamp, A Brinkman

Faculty of Engineering - Papers (Archive)

We demonstrate topological insulator (Bi2Te3) dc SQUIDs, based on superconducting Nb leads coupled to nano-fabricated Nb-Bi2Te3-Nb Josephson junctions. The high reproducibility and controllability of the fabrication process allow the creation of dc SQUIDs with parameters that are in agreement with design values. Clear critical current modulation of both the junctions and the SQUID with applied magnetic fields have been observed. We show that the SQUIDs have a periodicity in the voltage-flux characteristic of U0 of relevance to the ongoing pursuit of realizing interferometers for the detection of Majorana fermions in superconductor—topological insulator structures.


Enhancement Of The Electrochemical Capacitance Of Tio2 Nanotube Arrays Through Controlled Phase Transformation Of Anatase To Rutile, Maryam Salari, Seyed Hamed Aboutalebi, Alfred T. Chidembo, Ivan P. Nevirkovets, Konstantin Konstantinov, Hua-Kun Liu Jan 2012

Enhancement Of The Electrochemical Capacitance Of Tio2 Nanotube Arrays Through Controlled Phase Transformation Of Anatase To Rutile, Maryam Salari, Seyed Hamed Aboutalebi, Alfred T. Chidembo, Ivan P. Nevirkovets, Konstantin Konstantinov, Hua-Kun Liu

Faculty of Engineering - Papers (Archive)

Here, we report the fabrication of self-organized titania (TiO2) nanotube array supercapacitor electrodes through controlled phase transformation of TiO2, with aerial capacitances as high as 2.6 mF cm -2, which far exceeds the values so far reported in the literature. The role of phase transformation in the electrochemical charge–discharge behaviour of nanocrystalline TiO2 nanotubes is investigated and discussed in detail. The ease of synthesis and the exceptional electrochemical properties make these nanotube arrays an alternative candidate for use in energy storage devices.


A Laboratory Study Of Railway Ballast Behaviour Under Various Fouling Degree, Cholachat Rujikiatkamjorn, Buddhima Indraratna, Ngoc Trung Ngo, Matthew Coop Jan 2012

A Laboratory Study Of Railway Ballast Behaviour Under Various Fouling Degree, Cholachat Rujikiatkamjorn, Buddhima Indraratna, Ngoc Trung Ngo, Matthew Coop

Faculty of Engineering - Papers (Archive)

This paper presents a laboratory study of interface behavior between ballast and geogrid under various degree of fouling by coal fines. The stress-displacement behaviour of fresh and fouled ballast with geogrid was investigated through a series of large-scale direct shear tests where the fouling degree varied from 0% to 95% Void Contamination Index (VCI), at normal stresses ranging from 15kPa to 75kPa. The results showed that geogrid enhances the shear strength and increases apparent angle of shearing resistance, while only slightly reduces the vertical displacement of the composite geogrid-ballast system. However, when ballast was contaminated by coal fines, the influences …


Kinematic Analysis Of Electroactive Polymer Actuators As Soft And Smart Structures With More Dof Than Inputs, Rahim Mutlu, Gursel Alici, Weihua Li Jan 2012

Kinematic Analysis Of Electroactive Polymer Actuators As Soft And Smart Structures With More Dof Than Inputs, Rahim Mutlu, Gursel Alici, Weihua Li

Faculty of Engineering - Papers (Archive)

Electroactive polymer (EAP) actuators have been attracting the attention of researchers due to their muscle-like behaviour and unusual properties. Several modelling methods have been proposed to understand their mechanical, chemical, electrical behaviours or ‘electro-chemo-mechanical’ behaviour. However, estimating the whole shape or configuration of the EAP actuators has always been challenging due to their highly non-linear bending behaviour. This paper reports on an effective method to estimate the whole shape deflection of the EAP actuators by employing a so-called backbone approach. Tri-layer configured polypyrrole (PPy) based EAP actuators were used as a soft and smart structure with more degrees of freedom …


Microwave-Assisted Synthesis Of Flower-Like Structure Ε-Mno2 As Cathode For Lithium Ion Batteries, Dan Li, Guodong Du, Jieqiang Wang, Zaiping Guo, Zhixin Chen, Hua-Kun Liu Jan 2012

Microwave-Assisted Synthesis Of Flower-Like Structure Ε-Mno2 As Cathode For Lithium Ion Batteries, Dan Li, Guodong Du, Jieqiang Wang, Zaiping Guo, Zhixin Chen, Hua-Kun Liu

Faculty of Engineering - Papers (Archive)

Nanostructured flower-like ϵ-MnO2 and α-MnO2 nanowires were prepared by the microwave-assisted hydrothermal method at 110 °C and 140 °C. The ϵ-nanoflowers are about 500 nm in size and are composed of petals about 100 nm in length, while the α-nanowires are 20-30 μm in diameter and about 1 mm in length. The ϵ-MnO2 demonstrates higher initial discharge capacity, while the α-MnO2 shows greater cycling stability in different voltage ranges. Both phases of MnO2 show better cycling performance in ethylene carbonate (EC)/diethyl carbonate electrolyte (DEC) than in EC/dimethyl carbonate (DMC) electrolyte. The ϵ-MnO2 sample delivered …


Experimental Study On Adhesion Of Oxide Scale On Hot-Rolled Steel Strip, Xianglong Yu, Dongbin Wei, Xiaodong Wang, Zhengyi Jiang Jan 2012

Experimental Study On Adhesion Of Oxide Scale On Hot-Rolled Steel Strip, Xianglong Yu, Dongbin Wei, Xiaodong Wang, Zhengyi Jiang

Faculty of Engineering - Papers (Archive)

An experimental method was developed to study the adherence properties of the oxide scale formed on microalloyed low carbon steel after hot strip rolling. The evolution of the oxide scale during laminar cooling was investigated using Gleeble 3500 Thermal-Mechanical Simulator connected with a humid air generator. After the sample cooled down to ambient temperature, the oxide scale was protected by lacquer to prevent the scale from losing. Physicochemical characteristics of the oxide scale were examined and the adherence mechanism was discussed. Decomposed wustite a mixture of α-iron and magnetite (Fe3O4), can substantially improve the integrity of …


High Strength Thin-Walled Rectangular Concrete-Filled Tubular Slender Beam-Columns, Part Ii: Behaviour, Muhammad N. S Hadi, Qing Quan Liang, Vipulkumar I. Patel Jan 2012

High Strength Thin-Walled Rectangular Concrete-Filled Tubular Slender Beam-Columns, Part Ii: Behaviour, Muhammad N. S Hadi, Qing Quan Liang, Vipulkumar I. Patel

Faculty of Engineering - Papers (Archive)

Experimental and numerical research on full-scale high strength thin-walled rectangular steel slender tubes filled with high strength concrete has not been reported in the literature. In a companion paper, a new numerical model was presented that simulates the nonlinear inelastic behavior of uniaxially loaded high strength thin-walled rectangular concrete-filled steel tubular (CFST) slender beam-columns with local buckling effects. The progressive local and post-local buckling of thin steel tube walls under stress gradients was incorporated in the numerical model. This paper presents the verification of the numerical model developed and its applications to the investigation into the fundamental behavior of high …


Inelastic Stability Analysis Of High Strength Rectangular Concrete-Filled Steel Tubular Slender Beam-Columns, Vipulkumar Ishvarbhai Patel, Qing Quan Liang, Muhammad N. S Hadi Jan 2012

Inelastic Stability Analysis Of High Strength Rectangular Concrete-Filled Steel Tubular Slender Beam-Columns, Vipulkumar Ishvarbhai Patel, Qing Quan Liang, Muhammad N. S Hadi

Faculty of Engineering - Papers (Archive)

There is relatively little numerical study on the behavior of eccentrically loaded high strength rectangular concrete-filled steel tubular (CFST) slender beam-columns with large depth-to-thickness ratios, which may undergo local and global buckling. This paper presents a multi scale numerical model for simulating the interaction local and global buckling behavior of hlgh strength thin-walled rectangular CFST slender beam-columns under eccentric loading. The effects of progressive local buckling are taken into account in the mesoscale model based on fiber element formulations. Computational algorithms based on the Muller's method are developed to obtain complete load-deflection responses of CFST slender beam-columns at the macroscale …


Compaction And Strength Testing Of Industrial Waste Blends As Potential Port Reclamation Fill, Cholachat Rujikiatkamjorn, Buddhima Indraratna, Gabriele Chiaro, S Naeeni, S M. A Tasalloti Jan 2012

Compaction And Strength Testing Of Industrial Waste Blends As Potential Port Reclamation Fill, Cholachat Rujikiatkamjorn, Buddhima Indraratna, Gabriele Chiaro, S Naeeni, S M. A Tasalloti

Faculty of Engineering - Papers (Archive)

This paper reports on preliminary laboratory geotechnical investigations conducted to explore the compaction and unconfined compression strength (qu) behaviour of granular waste mixtures of coal wash (CW) and steel furnace slag (SFS). Compaction was conducted under relatively dry and submerged conditions. Proctor compaction test results show that the higher the SFS content, the greater the maximum dry density of mixtures, while the optimum moisture content (OMC) is rather constant. However, for mixtures compacted at their OMC, qu decreases with increasing SFS content. In contrast, for mixtures compacted under submergence and cured in seawater for up to 28 days, qu increases …


Assessment Of Ballast Fouling And Its Implications On Track Drainage, Nayoma Tennakoon, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Sanjay Nimbalkar Jan 2012

Assessment Of Ballast Fouling And Its Implications On Track Drainage, Nayoma Tennakoon, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Sanjay Nimbalkar

Faculty of Engineering - Papers (Archive)

Australian railways offer an efficient and economic mode for transporting freight and passengers across all States. Conventionally, rail tracks are positioned on ballast for reasons including economy (availability and abundance), rapid drainage, and high load bearing capacity. However, the ballast becomes fouled due to the intrusion of fines either from the subgrade or surface which impairs track drainage. In order to maintain serviceability, it is necessary to maintain adequate drainage capacity in the track. To identify the risk associated with fouling, it is important to understand the effects of the amount of fouling on drainage conditions. In this present study …


Specular Andreev Reflection In The Interface Of A Two-Dimensional Semiconductor With Rashba Spin-Orbit Coupling And A D-Wave Superconductor, Bo Lv, C Zhang, Zhongshui Ma Jan 2012

Specular Andreev Reflection In The Interface Of A Two-Dimensional Semiconductor With Rashba Spin-Orbit Coupling And A D-Wave Superconductor, Bo Lv, C Zhang, Zhongshui Ma

Faculty of Engineering - Papers (Archive)

We reveal that the recently discovered specular Andreev reflection (SAR) [C. W. J. Beenakker, Phys. Rev. Lett. 97, 067007 (2006)] can occur in semiconductors where the spin-orbit coupling is finite. We demonstrate this finding in the hybrid of a two-dimensional electron gas with Rashba spin-orbit coupling and a superconductor. In the limit of low density or a strong spin-orbit coupling, specular Andreev reflection is finite. We also show that unit electron-hole conversion is possible in a specular Andreev reflection due to the different topological structures of the equal-energy surface between electrons and holes. The SAR in the semiconductor is determined …


Performance Of A Novel Osmotic Membrane Bioreactor (Ombr) System: Flux Stability And Removal Of Trace Organics, Abdulhakeem Alturki, James Mcdonald, Stuart J. Khan, Faisal I. Hai, William E. Price, Long Nghiem Jan 2012

Performance Of A Novel Osmotic Membrane Bioreactor (Ombr) System: Flux Stability And Removal Of Trace Organics, Abdulhakeem Alturki, James Mcdonald, Stuart J. Khan, Faisal I. Hai, William E. Price, Long Nghiem

Faculty of Engineering - Papers (Archive)

Results reported here highlight the potential and several challenges in the development of a novel osmotic membrane bioreactor (OMBR) process for the treatment of municipal wastewater. Following the initial gradual decline, a stable permeate flux value was obtained after approximately four days of continuous operation. There was evidence of continuous deterioration of biological activity of the OMBR system, possibly due to the build-up of salinity in the reactor. The removal of 25 out of 27 trace organic compounds with molecular weight higher than 266 g/mol was above 80% and was possibly governed by the interplay between physical separation of the …


Track Stabilisation With Geosynthetics And Geodrains, And Performance Verification Through Field Monitoring And Numerical Modelling, Buddhima Indraratna, S Nimbalkar, Cholachat Rujikiatkamjorn Jan 2012

Track Stabilisation With Geosynthetics And Geodrains, And Performance Verification Through Field Monitoring And Numerical Modelling, Buddhima Indraratna, S Nimbalkar, Cholachat Rujikiatkamjorn

Faculty of Engineering - Papers (Archive)

All over the world, ballasted railway tracks form one of the major transportation networks designed to provide heavy haul freight and passenger traffic. However, large cyclic loading from heavy axle trains operating at high speeds often causes excessive deformation and degradation of ballast, as well as unacceptable differential settlement of compressible foundation and, or pumping of the soft subgrade soils. The problem becomes more severe under high impact loads due to rail or wheel imperfections, causing accelerated ballast breakage. A proper understanding of load transfer mechanisms and their effects on track deformations are essential prerequisites for minimising maintenance costs. The …


The Importance Of Scattering, Surface Potential, And Vanguard Counter-Potential In Terahertz Emission From Gallium Arsenide, D L. Cortie, R A. Lewis Jan 2012

The Importance Of Scattering, Surface Potential, And Vanguard Counter-Potential In Terahertz Emission From Gallium Arsenide, D L. Cortie, R A. Lewis

Faculty of Engineering - Papers (Archive)

It is well established that under excitation by short (<1 ps), above-band-gap optical pulses, semiconductor surfaces may emit terahertz-frequency electromagnetic radiation via photocarrier diffusion (the dominant mechanism in InAs) or photocarrier drift (dominant in GaAs). Our three-dimensional ensemble Monte Carlo simulations allow multiple physical parameters to vary over wide ranges and provide unique direct insight into the factors controlling terahertz emission. We find for GaAs (in contrast to InAs), scattering and the surface potential are key factors. We further delineate in GaAs (as in InAs) the role of a vanguard counter-potential. The effects of varying dielectric constant, band-gap, and effective mass are similar in both emitter types


The Role Of Ballast Fouling Characteristics On The Drainage Capacity Of Rail Substructure, Nayoma Tennakoon, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Sanjay Nimbalkar, Tim Neville Jan 2012

The Role Of Ballast Fouling Characteristics On The Drainage Capacity Of Rail Substructure, Nayoma Tennakoon, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Sanjay Nimbalkar, Tim Neville

Faculty of Engineering - Papers (Archive)

The ballast layer is designed to be free draining, but when the voids of the granular medium are wholly or partially filled due to the intrusion of fine particles, the ballast is considered to be “fouled”. In order to ensure acceptable track performance, it is necessary to maintain good drainage within the ballast layer. This paper critically examines the current methods commonly used for evaluating the degree of ballast fouling and, due to their limitations, a new parameter, Void Contaminant Index is introduced. A series of large-scale constant head hydraulic conductivity tests were conducted with different levels of fouling to …


Shear Strength Model For Sediment-Infilled Rock Discontinuities And Field Applications, Buddhima Indraratna, Wuditha N. Premadasa, Jan Anton Nemcik, Mylvaganam Jayanathan Jan 2012

Shear Strength Model For Sediment-Infilled Rock Discontinuities And Field Applications, Buddhima Indraratna, Wuditha N. Premadasa, Jan Anton Nemcik, Mylvaganam Jayanathan

Faculty of Engineering - Papers (Archive)

Discontinuities have a great influence on the reduction of rock mass shear strength depending on the geometry, roughness and the nature of infill sediments. These discontinuities are generally filled with different types of sediments. When the infill sediments are saturated, they make a considerable impact on the overall strength of the rock mass. Most infilled discontinuities in the field are overconsolidated due to various factors such as climatic and weathering conditions, as well as hydrothermal alteration. The increase in the thickness of joint infill subdues the otherwise prominent role of joint roughness. This paper presents some of the existing mathematical …


Analysis Of Jet Characteristics And Structural Optimization Of A Liquamatic Fire Water Monitor With Self-Swinging Mechanism, Guoliang Hu, Ming Long, Juxing Liang, Weihua Li Jan 2012

Analysis Of Jet Characteristics And Structural Optimization Of A Liquamatic Fire Water Monitor With Self-Swinging Mechanism, Guoliang Hu, Ming Long, Juxing Liang, Weihua Li

Faculty of Engineering - Papers (Archive)

This paper presents analysis and optimization of a liquamatic fire water monitor with a novel self-swinging mechanism. The design of the self-swinging mechanism has adopted a four-bar linkage driven by an impeller. The Fluent software was used to simulate the internal flow performance of the fire water monitor. In particular, the effects of the cross-sectional shape, diameters of the monitor body, inlet water pressure, and drive set of the self-swinging mechanism on the jet characteristics were analyzed. These analyses have led to optimal structural parameters of the flow channel. A prototype of the fire ware monitor was manufactured, and the …


Consolidation Behavior Of Soil-Cement Column Improved Ground, Suksun Horpibulsuk, Avirut Chinkulkitniwat, Arnon Cholphatsorn, Jirayut Suebsuk, Martin D. Liu Jan 2012

Consolidation Behavior Of Soil-Cement Column Improved Ground, Suksun Horpibulsuk, Avirut Chinkulkitniwat, Arnon Cholphatsorn, Jirayut Suebsuk, Martin D. Liu

Faculty of Engineering - Papers (Archive)

Columnar inclusion is one of the effective and widely used methods for improving the engineering properties of soft clay ground. This article investigates the consolidation behavior of composite soft clay ground using both physical model tests under an axial-symmetry condition and finite element simulations using the PLAXIS 2D program. It was determined that the final settlement and the rate of consolidation of the composite ground depended on the stress state. For an applied stress that is much lower than the failure stress, the final settlement of the composite ground was lower, and the consolidation was rapid. When the soil–cement column …


Permeable Reactive Barrier (Prb) Technology: An Innovative Solution For The Remediation Of Acidic Groundwater From Acid Sulphate Soil (Ass) Terrain, Laura Banasiak, Buddhima Indraratna Jan 2012

Permeable Reactive Barrier (Prb) Technology: An Innovative Solution For The Remediation Of Acidic Groundwater From Acid Sulphate Soil (Ass) Terrain, Laura Banasiak, Buddhima Indraratna

Faculty of Engineering - Papers (Archive)

The remediation of acidic groundwater contaminated with potentially toxic metals such as aluminium (Al) and iron (Fe) resulting from the oxidation of sulphidic materials in acid sulphate soils (ASSs) is a challenging geo-environmental problem that requires innovative engineering solutions. In low-lying coastal floodplains, the remediation strategies of groundwater manipulation (e.g. fixed-level weirs) and tidal buffering (e.g. two-way modified floodgates) are not feasible due to the risk of flooding during heavy rainfall events and their inability to prevent pyritic oxidation. In view of this in 2006, the first pilot subsurface permeable reactive barrier (PRB) using recycled concrete for the remediation of …