Engineering Commons^™

Removal Of Inorganic Trace Contaminants By Electrodialysis In A Remote Australian Community, L J. Banasiak, A I. Schafer

Faculty of Engineering - Papers (Archive)

Water provision for developing countries is a critical issue as a vast number of lives are lost annually due to lack of access to safe drinking water. The presence and fate of inorganic trace contaminants is of particular concern. Trace inorganic contaminants have been found in elevated concentrations in drinking waters supplied directly from brackish groundwaters in developing countries. Desalination and the removal of trace inorganic contaminants from bore water sources from a remote community in Australia using electrodialysis (ED) were investigated. The influence of applied voltage on the removal of the trace contaminants was evaluated. While the results from …

Adding Value To Physics Labs To Help Build Confident, Knowledgeable Teachers, Lorna Jarrett, Brian Ferry, George J. Takacs

Faculty of Engineering - Papers (Archive)

Abstract: This pilot study is being conducted by an interdisciplinary team and is funded through the University of Wollongong Education Strategies Development Fund. The project focuses on the first-year physics laboratories of pre- service teachers enrolled in Bachelor of Science Education degrees. It aims to make the laboratory experience more aligned to the needs of future science and physics teachers, contributing to their confidence in using apparatus in the classroom and their effectiveness as communicators who can explain concepts fluently from a background of deep understanding. According to Mulhall (2006) and Johnston and Millar (2000), misconceptions are common even among …

Consolidation Analysis Of A Stratified Soil With Vertical And Horizontal Drainage Using The Spectral Method, Rohan Walker, Buddhima Indraratna

Faculty of Engineering - Papers (Archive)

A novel use of the spectral method to determine excess pore water pressure during vertical consolidation of multi-layered soil with time constant material properties is presented, considering a unit cell with combined vertical and radial drainage. Equal strain conditions are assumed in the analysis. The novel adoption of material properties that vary in a linear fashion with depth allows arbitrary distributions of properties to be modelled. By incorporating surcharge and vacuum loading that vary with both depth and time, a wide range of consolidation problems can be analysed. The spectral method is a meshless approach producing a series solution to …

Ground Improvement/Grouting/Dredging, Buddhima Indraratna

Faculty of Engineering - Papers (Archive)

Due to the rapid increase in population, industrial and construction boom especially in the urban as well as coastal regions of many countries have considerably intensified the inevitable need for infrastructure development on problematic soils including soft compressible clays, deposits with low bearing capacities, soils prone to erosion and collapse upon wetting, highly fractured and jointed rock mass among other geological deposits. Good quality geologic materials for construction are also becoming scarce, exacerbated by numerous environmental constraints in various countries. Due to these reasons and environmental restrictions on certain public works, ground improvement has now become an integrated and essential …

Online Performance Evaluation Of Alternative Control Strategies For Building Cooling Water Systems Prior To In-Situ Implementation, Zhenjun Ma, Shengwei Wang, Fu Xiao

Faculty of Engineering - Papers (Archive)

This paper presents the online test and evaluation of the performance of five practical control strategies (fixed set-point control method, fixed approach control method, two near optimal strategies and one optimal strategy) for building cooling water systems to identify the best strategy for future field validation. All of these strategies were tested and evaluated in a simulated virtual environment similar to the situation when they are actually implemented in practice. A virtual building system representing the real building and its central chilling system was developed and used to test the operational performance of the system controlled by different strategies. The …

In Situ Study Of Dynamic Recrystallization And Hot Deformation Behavior Of A Multiphase Titanium Aluminide Alloy, Klaus-Dieter Liss, Thomas Schmoelzer, Kun Yan, Mark H. Reid, Matthew Peel, Rian J. Dippenaar, Helmut Clemens

Faculty of Engineering - Papers (Archive)

Hot-compression tests were conducted in a high-energy synchrotron x-ray beam to study in situ and in real time microstructural changes in the bulk of a β-solidifying titanium aluminide alloy. The occupancy and spottiness of the diffraction rings have been evaluated in order to access grain growth and refinement, orientation relationships, subgrain formation, dynamic recovery, and dynamic recrystallization, as well as phase transformations. This method has been applied to an alloy consisting of two coexisting phases at high temperature and it was found that the bcc β-phase recrystallizes dynamically, much faster than the hcp α-phase, which deforms predominantly …

A Correlation Between Transport Current Density And Grain Connectivity In Mgb2/Fe Wire Made From Ball-Milled Boron, X Xu, J H. Kim, S X. Dou, S Choi, J H. Lee, H W. Park, M Rindfleish, M Tomsic

Faculty of Engineering - Papers (Archive)

Studies of the magnetic field dependence of the transport critical current density (J_ct) and the grain connectivity of MgB₂/Fe wires fabricated from ball-milled boron have been conducted in detail, and strong correlations have been found, as evidenced by differences in grain size, critical transition temperature, and resistivity. It was observed that the samples fabricated by ball milling had relatively small grain sizes, resulting in a strong field dependence of the J_ct in the high field region. On the other hand, the ball-milled boron was associated with poor connectivity between adjacent grains. It is clearly …

Superconducting Properties Of Mgb2 Wire Using Ball Milled Low Purity Boron, Xun Xu, Jung Ho Kim, Yun Zhang, Yue Zhao, Matthew Rindfleisch, Michael Tomsic

Faculty of Engineering - Papers (Archive)

MgB_2/Fe wire samples were prepared by using ball-milled 96% boron (B) powder with strong semi-crystalline phase. We observed samples that contained ball-milled 96% B in comparison with one made from as-supplied commercial 96% B, with the results showing a significant enhancement in the high field transport critical current density (J_ct) due to small grain size and better reactivity. However, the inter-grain connectivity became worse, which could lead to poor J_ct in low field and an increased level of disorder.

Thermodynamic Modelling Of High Temperature Systems, Winny Wulandari, Geoffrey A. Brooks, M Akbar Rhamdhani, Brian J. Monaghan

Faculty of Engineering - Papers (Archive)

• Thermodynamic modeling is valuable tool to predict phase equilibria in high temperature metals processing
• Thermo chemical packages makes modeling easier, but the fundamental knowledge such as how we determine the phase, species, and activity behaviour are the intellectual aspects
• An example in magnesium impurities illustrate both the predictive power of thermodynamic modelling but also the dilemmas associated with solution behaviour

Distribution Of Impurities In Magnesium Via Silicothermic Reduction, Winny Wulandari, Akbar Rhamdhani, Geoff Brooks, Brian J. Monaghan

Faculty of Engineering - Papers (Archive)

The desire for light weight materials, particularly in the automotive field, is fuelling greater magnesium production. The Pidgeon process is currently the most widely used process for the production of magnesium. This batch process involves reduction of dolomite by ferro-silicon, carried out at temperature between 1100-1200oC under vacuum in a retort, producing magnesium vapour which is then cooled and collected as a condensate. The major attractions of the process are its simplicity and low capital cost; however, the process is also labour and energy intensive. The Magnetherm process is also a vacuum batch process based on similar chemistry but operates …

Rapid Reduction Of Copper Sulfide (Cu2s) With Elemental Fe And Mg Using Electrical Discharge Assisted Meachanical Milling (Edamm), Andrzej Calka, David Wexler, Brian J. Monaghan, A Mosbah, P Balaz

Faculty of Engineering - Papers (Archive)

The electric discharge assisted mechanochemical milling technique has been applied to the reduction of copper sulphide using either elemental magnesium or elemental iron as the reducing agent. X-ray diffraction was employed for phase identification of starting materials and reaction products. After only 5 min processing using the Electric discharge assisted mechanical milling (EDAMM) method, Cu2S + Mg can be fully reduced to Cu + MgS with small amount of CuO, and Cu2S + Fe can be partially reduced to Cu + Cu5FeS4 (bornite). Secondary electron imaging combined with X-ray mapping was used to investigate the distribution of elements within the …

The Combined Influence Of Connectivity And Disorder On Jc And Tc Performances In Mgxb2+10 Wt % Sic, Wenxian Li, Rong Zeng, Lin Lu, Y Li, S. X. Dou

Faculty of Engineering - Papers (Archive)

The influences of connectivity and disorder on the critical current density J_c are discussed to clarify the different mechanisms of J_c(H) enhancement in different magnetic field ranges. Excess Mg in Mg_xB₂+10 wt % SiC composites effectively improves the connectivity, as evidenced by both the resistivity properties and the Raman scattering. The promising J_c(H) of Mg_1.15B₂+10 wt % SiC is attributed to both the high connectivity and the improved irreversibility field, H_irr, which is in agreement with the Raman fitting analysis. Raman …

Geotechnical Assessment Of Skin Reinforcement In Underground Mines, Jan Anton Nemcik, Ian Porter, Ernest Y. Baafi, Chris A. Lukey

Faculty of Engineering - Papers (Archive)

Current advances in roof support automation require a fast and effective skin reinforcement of underground mine roadways. To satisfy these needs a strong and tough fibre reinforced polymeric alternative is emerging as a logical substitute to the old steel mesh support system. Differences between steel mesh and polymer skin behaviour are investigated. Computational models are utilised to compare these two skin support systems with a view to optimising the performance needed for effective roadway skin reinforcement. In particular, development of a strong and resistant shell that minimises movement along the fractured rock and coal surfaces found between the roof bolt …

Cyclic Deformation Of Advanced High-Strength Steels: Mechanical Behavior And Microstructural Analysis, Timothy B. Hilditch, Ilana B. Timokhina, Leigh T. Robertson, E V. Pereloma, Peter D. Hodgson

Faculty of Engineering - Papers (Archive)

The fatigue properties of multiphase steels are an important consideration in the automotive industry. The different microstructural phases present in these steels can influence the strain life and cyclic stabilized strength of the material due to the way in which these phases accommodate the applied cyclic strain. Fully reversed strain-controlled low-cycle fatigue tests have been used to determine the mechanical fatigue performance of a dual-phase (DP) 590 and transformation-induced plasticity (TRIP) 780 steel, with transmission electron microscopy (TEM) used to examine the deformed microstructures. It is shown that the higher strain life and cyclic stabilized strength of the TRIP steel …

First-Principles Study On The Enhancement Of Lithium Storage Capacity In Boron Doped Graphene, Xianlong Wang, Zhi Zeng, Hyojun Ahn, Guoxiu Wang

Faculty of Engineering - Papers (Archive)

The adsorption of Li ions on boron doped graphene was investigated using a first-principles method. Our results show that, as boron doping turns graphene into an electron-deficient system, more Li ions can be captured around boron doped centers than in pristine graphene. One boron atom doped into graphene (6C ring unit) can adsorb six Li ions, which indicates that boron doped graphene is an efficient Li-ion storage material for lithium batteries. Further investigations show that, under limited conditions, boron doped graphene (BC₅) can form Li₆BC₅ compound after Li-ion adsorption, corresponding to a lithium storage capacity …

A Comparative Study On Field, Temperature, And Strain Dependences Of The Critical Current For Doped And Undoped Mgb2 Wires Based On The Percolation Model, Sangjun Oh, Jung Ho Kim, Kyuhwan Cho, Chulhee Lee, Chan-Joong Kim, S. X. Dou, M Rindfleisch, Mike Tomsic, Jung-Ho Ahn

Faculty of Engineering - Papers (Archive)

Field, temperature, and strain dependences of the critical current for a SiC doped multifilamentary in situ MgB₂ wire have been studied. Measurement results were compared with that of the undoped wire, and the origin of the difference in the critical current is discussed. The critical current can be calculated with the percolation model considering the effect of anisotropy. The temperature dependence of the fitting parameters, the upper critical field along the ab-plane, and c-axis is compared with the dirty-limit two-gap theory. To assess the validity of the fitting parameters, resistive transition has been measured especially to …

Synthesis Of Smfeaso By An Easy And Versatile Route And Its Physical Property Characterization, V P. Awana, Anand Pal, Arpita Vajpayee, H Kishan, Gustavo A. Alvarez, K Yamaura, E Takayama-Muromachi

Faculty of Engineering - Papers (Archive)

We report synthesis, structure, electrical transport, and heat capacity of SmFeAsO. The title compound is synthesized by one-step encapsulation of stoichiometric FeAs, Sm, and Sm₂O₃ in an evacuated (10⁻⁵ Torr) quartz tube by prolong (72 h) annealing at 1100 °C. The as-synthesized compound is crystallized in tetragonal structure with P4/nmm space group having lattice parameters a = 3.937 26(33) A and c = 8.498 02(07) A. The resistance (R-T) measurements on the compound exhibited ground state spin-density-wave (SDW)-like metallic steps below 140 K. Heat capacity C_P( …

Re-Entrant Ferromagnet Prmn2ge0.8si1.2: Magnetocaloric Effect, S X. Dou, Jianli Wang, Rong Zeng, Chung-Kiak Poh, Stewart J. Campbell, S J. Kennedy

Faculty of Engineering - Papers (Archive)

The structural and magnetic properties of the re-entrant ferromagnet PrMn₂Ge_0.8Si_1.2 have been investigated by various experimental methods. Similar to the canonical re-entrant ferromagnet SmMn₂Ge₂, multiple magnetic phase transitions have been detected in PrMn₂Ge_0.8Si_1.2 over the temperature range from 10 to 550 K with re-entrant ferromagnetism occurring around ∼ 54 K. The magnetocaloric effect has been measured in terms of the isothermal magnetocaloric entropy change and found to be positive at the re-entrant ferromagnetic transition with a maximum value of around 1.9 J/kg K at 58 K …

The Influence Of University Entry Scores On Performance In Engineering Mechanics, Giles Thomas, Alan Henderson, Thomas L. Goldfinch

Faculty of Engineering - Papers (Archive)

An ongoing study into the causes of poor student performance in engineering mechanics has uncovered some intriguing data on the relationships between students’ university entry scores and their performance in engineering mechanics courses. Statistical analysis has shown that the expected correlations between this key measure used to determine students eligibility for study and engineering mechanics score either do not exist, or are too weak to base educational interventions on. However, students’ entry scores have instead been shown to provide a ‘risk factor’, whereby students’ risk of failing the subject can be determined by entry score ranges. These risk factors may …

Hot Ductility Of Nb- And Ti-Bearing Microalloyed Steels And The Inlfuence Of Thermal History, Kristin R. Carpenter, Rian J. Dippenaar, Chris Killmore

Faculty of Engineering - Papers (Archive)

The hot ductility of Nb, Ti, and Nb-Ti containing steels has been studied under direct-cast conditions. A Gleeble 3500 thermomechanical simulator was used to determine hot ductility over the temperature range 1100 °C to 700 °C at a low strain rate of 7.5 × 10⁻⁴ s⁻¹. Tensile samples were cooled at two different cooling rates, 100 °C/min and 200 °C/min, simulating, respectively, thick and thin slab casting processes. Complex thermal patterns designed to simulate the cooling conditions experienced near the surface of a slab during continuous casting were carried out for the Nb-Ti steel. The Nb-Ti steel …

Phase Transformations In (111) Si After Spherical Indentation, Ayesha J. Haq, Paul G. Munroe

Faculty of Engineering - Papers (Archive)

Phase transformations in (111) Si after spherical indentation have been investigated by cross-sectional transmission electron microscopy. Even at an indentation load of 20 mN,a phase transformation zone including the high-pressure crystalline Si phases was observed within the residual imprints. The volume of the transformation zone, as well as that of the crystalline phases increased with the indentation load. Below the transformation zone, slip was found to occur on {311} planes rather than on {111}planes, usually observed on indentation of (100) Si. The distribution of defects was asymmetric, and for indentation loads up to 80 mN, their density was significantly lower …

Observation Of Precipitation Evolution In Fe-Ni-Mn-Ti-Al Maraging Steel By Atom Probe Tomography, E V. Pereloma, R.A. Stohr, M.K Miller, S P. Ringer

Faculty of Engineering - Papers (Archive)

We describe the full decomposition sequence in an Fe-Ni-Mn-Ti-Al maraging steel during isothermal annealing at 550 °C. Following significant pre-precipitation clustering reactions within the supersaturated martensitic solid solution, (Ni,Fe)₃Ti and (Ni,Fe)₃(Al,Mn) precipitates eventually form after isothermal aging for ~60 seconds. The morphology of the (Ni,Fe)₃Ti particles changes gradually during aging from predominantly plate-like to rod-like, and, importantly, Mn and Al were observed to segregate to these precipitate/matrix interfaces. The (Ni,Fe)₃(Al,Mn) precipitates occurred at two main locations: uniformly within the matrix and at the periphery of the (Ni,Fe)₃Ti particles. We relate …

Studies Of The Characteristics Of A Silicon Neutron Sensor, Igor E. Anokhin, Oleg S. Zinets, Anatoly B. Rosenfeld, Michael L. Lerch, M. Yudelev, V. L. Perevertaylo, Mark I. Reinhard, Marco Petasecca

Faculty of Engineering - Papers (Archive)

Electrical characteristics and neutron dosimetry properties of silicon based p-i-n diodes are presented in support of the applications in the sensors for beam monitoring and medical physics. Both the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of silicon planar p-i-n diode sensors with cylindrical geometry have been theoretically modeled and experimentally measured. The shifts of the forward and reverse diode characteristics of the sensors versus the neutron dose have been obtained. It is shown that the neutron irradiation caused shift of the forward voltage of the p-i-n diodes is proportional to the current at which it is measured in the case …

A Variable Stiffness Mr Damper For Vibration Suppression, Xianzhou Zhang, Weihua Li, Yang Zhou

Faculty of Engineering - Papers (Archive)

This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness damper and analysis its applications in vibration suppression. The MR fluid isolator used a MR valve control unit and bladders to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The effective stiffness and damping coefficients of the isolator under various magnetic fields were identified and the dynamic performances of isolator were evaluated with simulation. …

Thz Generation By Optical Rectification Involving High-Index Planes, Krunal Radhanpura, Stuart Hargreaves, Roger A. Lewis

Faculty of Engineering - Papers (Archive)

We report a theoretical and experimental study of the generation of THz radiation by optical rectification from high-index planes of GaAs crystals.

Preparing Mgb2 With Excessive Mg Environment Sintering And Two-Step Sintering Approach, S X. Dou, Sihai Zhou, Alexey V. Pan, Jaimoo Yoo, Yun Zhang, Kookchae Chung

Faculty of Engineering - Papers (Archive)

MgB₂ superconductors were made with two processes in this work. In one case, the SiC doped MgB₂ pellets were sintered in excessive Mg medium. It is found that the samples sintered in excessive Mg medium present Mg-rich composition comparing with the one sintered in Ar gas. The density is higher and the resistance is lower due to the penetration of the Mg into the pores and grain boundary of MgB₂, which is beneficial to the J_c improvement. In the other case, a two-step process was employed to make MgB₂. J_c of the …

Quantitative Description Of Critical Current Density In Ybco Films And Multilayers, Alexey V. Pan, Serhiy Pysarenko, S X. Dou

Faculty of Engineering - Papers (Archive)

The vortex pinning model based on the presence of the large number of edge dislocations in high quality YBa₂Cu₃O₇ (YBCO) films and multilayers has been refined. By introducing the pinning potential of a chain of individual edge dislocations, we have been able not only to describe the critical current density dependence on the applied magnetic field over its entire range, but also to extract the microstructural parameters in the films, such as inter-dislocation spacing and average domain size, without employing sophisticated microstructural analysis. The model applicability and its results have been verified with the help …

Spin Wave Scattering And Interface Magnetism In Superconducting-Ferromagnet-Superconducting Hybrid Structures, Gustavo A. Alvarez, Xiaolin Wang, T Puzzer, Germanas Peleckis, S. X. Dou

Faculty of Engineering - Papers (Archive)

In this work we report on interlayer spin-polarized transport studies carried out on YBa₂Cu₃O_7-δ/La_2/3Sr_1/3MnO₃/YBa₂Cu₃O_7-δ thin film multilayers. Anisotropic YBa₂Cu₃O_7-δ high-temperature superconductors (YBCO) and the manganite La_2/3Sr_1/3MnO₃ (LSMO) are layered metallic systems where the c-axis interlayer current transport occurs via sequential tunneling of charge carriers. The temperature dependence of the resistance R(T) for different applied fields shows that these heterostructures are clearly influenced by both the insulator-to-metal …

Hydrothermal Synthesis And Optical, Magnetic And Supercapacitance Properties Of Nanoporous Cobalt Oxide Nanorodes, Guoxiu Wang, Xiaoping Shen, Josip Horvat, Bei Wang, Hao Liu, David Wexler, Jane Yao

Faculty of Engineering - Papers (Archive)

Nanoporous cobalt oxide nanorods were synthesized by a hydrothermal method. Transmission electron microscopy analysis showed that the individual Co₃O₄ nanorods have a nanoporous structure, consisting of the textured aggregations of nanocrystals. Optical properties of Co₃O₄ nanorods were characterized by Raman and UV−vis spectroscopy. Magnetic property measurement shows that Co₃O₄ nanorods have a low Néel transition temperature of 35 K. We observed quite significant exchange bias for nanoporous Co₃O₄ nanorods, indicating the existence of magnetic coupling between the nanocrystals in Co₃O₄ nanorods. When applied as electrode …

Simulation Of Impulsive Loading On Column Using Inflatable Airbag Technique, Alexander Remennikov, J Y Richard Liew, Kong Sih Ying, K W. Kang

Faculty of Engineering - Papers (Archive)

The purpose of this study was to simulate impulsive loading on columns by an innovative lab-based experimental technique that utilises inflatable airbags. Mild and stainless steel hollow sectioin columns with effective lengths of 955mm and under simply supported condition were used in this study.