Engineering Commons^™

Introduction To The Geant4 Simulation Toolkit, Susanna Guatelli, D Cutajar, Bradley Oborn, Anatoly B. Rosenfeld

Faculty of Engineering - Papers (Archive)

Geant4 is a Monte Carlo simulation Toolkit, describing the interactions of particles with matter. Geant4 is widely used in radiation physics research, from High Energy Physics, to medical physics and space science, thanks to its sophisticated physics component, coupled with advanced functionality in geometry description. Geant4 is widely used at the Centre for Medical Radiation Physics (CMRP), at the University of Wollongong, to characterise and optimise novel detector concepts, radiotherapy treatments, and imaging solutions. This lecture consists of an introduction to Monte Carlo method, and to Geant4. Particular attention will be devoted to the Geant4 physics component, and to the …

Coupling Effects Of Feed Solution Ph And Ionic Strength On The Rejection Of Boron By Nf/Ro Membranes, Kha Tu, Long Nghiem, Allan Chivas

Faculty of Engineering - Papers (Archive)

The coupling effects of solution pH and ionic strength on boron rejection by nanofiltration (NF) and reverse osmosis (RO) membranes were investigated. Two NF membranes (namely NF270 and NF90) and three RO membranes (namely BW30, SW30 and UTC80) were used to provide a full spectrum of NF/RO membranes. The rejection of boron by all five membranes was pH-dependent. The dependency of boron rejection on the feed solution pH became much more substantial as the nominal salt (sodium or calcium) rejection value of the membrane decreased. At pH 11, boron rejections by the NF90 and the NF270 membranes were only 10% …

Direct Observation Of Local Potassium Variation And Its Correlation To Electronic Inhomogeneity In (Ba1-Xkx)Fe2as 2 Pnictide, Wai Kong Yeoh, Baptiste Gault, X.Y. Cui, C. Zhu, P Moody, L. Li, Rongkun Zheng, Wenxian Li, Xiaolin Wang, S. X. Dou, G.L Sun, C T Lin, S P. Ringer

Faculty of Engineering - Papers (Archive)

Local fluctuations in the distribution of dopant atoms are thought to cause the nanoscale electronic disorder or phase separation in pnictide superconductors. Atom probe tomography has enabled the first direct observations of dopant species clustering in a K-doped 122-phase pnictide. First-principles calculations suggest the coexistence of static magnetism and superconductivity on a lattice parameter length scale over a wide range of dopant concentrations. Our results provide evidence for a mixed scenario of phase coexistence and phase separation, depending on local dopant atom distributions.

Treatment Of Saline Aqueous Solutions Using Direct Contact Membrane Distillation, Long Nghiem, Florian Hildinger, Faisal I. Hai, Tzahi Cath

Faculty of Engineering - Papers (Archive)

The treatment of highly saline aqueous solutions using direct contact membrane distillation (DCMD) was evaluated in this study. Experiments were conducted using a flat sheet polytetrafluoroethylene membrane with nominal pore size of 0.22 µm. Seawater, reverse osmosis (RO) concentrate collected from a wastewater reclamation plant, and a synthetic solution containing 2,000 mg/L of CaSO₄ were selected as the representative saline solutions. A gradual decline in permeate flux was observed at the beginning of the experiments when the seawater and RO concentrate solutions were treated using the DCMD process, most likely due to initial organic fouling and scaling. In contrast, …

Magnetocaloric Effect In Layered Ndmn2ge0.4si1.6, Jianli Wang, S.J Campbell, J.M Cadogan, A J Studer, Rong Zeng, S. X. Dou

Faculty of Engineering - Papers (Archive)

A giant magnetocaloric effect has been observed in NdMn₂Ge_0.4Si_1.6 associated with the first-order magnetic phase transition from antiferromagnetism to ferromagnetism around T_C = 36 K. The magnetic entropy change –ΔS_M and adiabatic temperature change ΔT_ad have been determined from magnetization and specific heat measurements (B = 0–5 T) with –ΔS_M calculated by the Maxwell relation and Clausius–Clapeyron method. The values –ΔSMmax = 12.3 J kg⁻¹ K⁻¹ and refrigerant capacity ∼ 95 J/kg for ΔB = 0–2 T as derived from …

Two-Color Terahertz Response In Bilayer Graphene Nanoribbons With Spin-Orbit Coupling, Junfeng Liu, Bo Wang, Zhongshui Ma, Chao Zhang

Faculty of Engineering - Papers (Archive)

We demonstrate that spin-orbit coupling can give rise to a strong terahertz response in metallic armchair bilayer graphene nanoribbons. The combination of the interlayer coupling and the spin-orbit coupling leads to double resonant optical response in the low frequency regime. The frequency separation of the two excitations is tunable with a gate voltage.

Slope Hazard Assessment On A Coast Road In New South Wales, Australia, M. Hendrickx, R A. Wilson, A T. Moon, I E. Stewart, Phillip N. Flentje

Faculty of Engineering - Papers (Archive)

Lawrence Hargrave Drive was constructed in 1878 and has experienced a continuance of slope failures including rock falls, debris flows and embankment collapses. In 2003 a section of the road was closed for safety reasons. An Alliance between the state government and private industry was formed to develop an engineering solution to reduce the risk to ‘acceptable’ levels. Assessment of slope hazards was completed with the aid of geological mapping, interpretation of aerial photographs, archived government reports, historical photo and newspaper collections and a GIS based landslide inventory. Historical photographs provided important evidence on erosion rates and the size, nature …

Treatment Of High Tds Liquid Waste: Is Zero Liquid Discharge Feasible?, Alexander Robertson, Long Nghiem

Faculty of Engineering - Papers (Archive)

A zero liquid discharge treatment system for the disposal of saline industrial liquid waste was proposed and evaluated in this study. Microfiltration was selected as a pretreatment process after a qualitative assessment against `conventional¿ options. Two reverse osmosis (RO) membranes were examined for the pre-concentration of liquid waste using a laboratory scale membrane rig. The results were used to validate the use of the ROSA simulation package. ROSA simulation was conducted with liquid waste having a range of salinity of up to 100,000 ppm of total dissolved solid (TDS). Results reported here indicated that RO membranes were highly suitable for …

Professional Ethics Education In Engineering, Brad Stappenbelt

Faculty of Engineering - Papers (Archive)

There is much debate surrounding professional ethics education, in particular surrounding the question of whether professional ethics can be taught at all (Steneck, 1999; Bauer and Adams, 2005). Professional ethics instruction in engineering is commonly conducted by examining case studies in light of the code of conduct of a suitable professional body. Although graphical presentations of spectacular failures, sobering stories of the repercussions and the solid framework provided by the tenets of a code of ethics may leave a lasting impression, students generally gain their professional identity from relatives and colleagues (Loui, 2005). Their professional ethics tend to be mostly …

Energy-Loss Rate Of A Fast Particle In Graphene, Yee Sin Ang, Chao Zhang, Chun Kee

Faculty of Engineering - Papers (Archive)

The energy-loss rate of a fast particle in graphene is studied. The energy-loss rate always increases with increasing incident particle energy, which is quite unusual when compared to electron gas in normal metal. Graphene exhibits a “discriminating” behavior where there exists a low energy cut-off below which the scattering process is strictly forbidden, leading to lossless traverse of an external particle in graphene. This low energy cutoff is of the order of nearest neighbor hopping bandwidth. Our results suggest that backscattering is also absent in the external particle scattering of graphene.

Flac3d Analysis On Soil Moving Through Piles, E H. Ghee, W D. Guo

Faculty of Engineering - Papers (Archive)

Piles may be utilized as deep foundations or employed to support offshore structures, which may be subjected to passive loading due to lateral soil movements. The safety of the piled foundations depends on the additional stresses induced. This issue has been investigated recently by conducting model tests on single piles and on pile groups with a new apparatus developed by the authors. Typical test results were analysed and reported previously. In this paper three-dimensional finite difference analyses are reported: (1) to predict the results of two model tests (with and without axial load); and (2) to investigate the effect of …

Structure Nonlinearity And Response Of Laterally Loaded Piles, Wei Dong Guo, B T. Zhu

Faculty of Engineering - Papers (Archive)

In light of a generic limiting force profile (LFP), closed·form solutions for laterally loaded free- and fixed- head piles in elastic-plastic media have been developed, and implemented by the first author into a spreadsheet program called GASLFP. The solutions offer an expeditious and sufficiently accurate prediction of response of lateral piles. Conversely, they allow input parameters to be deduced using measured pile response, as has been conducted for over 70 test (elastic) piles to date. Nevertheless. structure nonlinearity of pile body is an important issue at a large deflection.

In this paper, a semi·empirical approach is established to capture pile …

Crystal Plasticity Finite Element Modelling Of Surface Roughness And Texture Of Metals, H Li, Z Jiang, D Wei, J Han

Faculty of Engineering - Papers (Archive)

A crystal plasticity finite element method (CPFEM) model was developed to analyse the surface roughness transfer and texture of metals during metal forming. In order to investigate the crystal slip mechanism and influence of different polycrystalline models (Taylor-type model and finite element polycrystalline model) on finite element modelling, the uniaxial compression of FCC pure aluminum was carried out in laboratory, and the Taylor-type and finite element polyaystalline models are separately employed in the finite element software ABAQUS to simulate the development of the deformation texture by rate dependent crystal constitutive equations during three different deformation modes (free compression, uniaxial planar …

Ammonium Octahydrotriborate (Nh4b3h8): New Synthesis, Structure, And Hydrolytic Hydrogen Release, Zhenguo Huang, Xuenian Chen, Teshome Yisgedu, Edward A. Meyers, Sheldon Shore, J C. Zhao

Australian Institute for Innovative Materials - Papers

A metathesis reaction between unsolvated NaB₃H₈ and NH₄Cl provides a simple and high-yield synthesis of NH₄B₃H₈. Structure determination through X-ray single crystal diffraction analysis reveals weak N—H^δ+- - -H^δ-—B interaction in NH₄B₃H₈ and strong N—H^δ+—H^δ-—B interaction in NH₄B₃H₈·18-crown-6·THF adduct. Pyrolysis of NH₄B₃H₈ leads to the formation of hydrogen gas with appreciable amounts of other volatile boranes below 160°C. Hydrolysis experiments show that …

High-Capacity Hydrogen Release Through Hydrolysis Of Nab3h8, Zhenguo Huang, Xuenian Chen, Teshome Yisgedu, J C. Zhao, Sheldon Shore

Australian Institute for Innovative Materials - Papers

NaB3H8 has advantages over NaBH4 and NH3BH3, two most widely studied chemical hydrides for hydrogen storage via hydrolysis. NaB3H8 has an extraordinary high solubility in water and thus possesses a high theoretical capacity of 10.5 wt% H via hydrolysis, in contrast to 7.5 wt% for NaBH4 and 5.1 wt% for NH3BH3. NaB3H8 is reasonably stable in water which makes it unnecessary to add corrosive NaOH as a stabilizer as the case for NaBH4. Furthermore, hydrolysis of NaB3H8 can be catalyzed by a Co-based catalyst with fast kinetics that is comparable to Ru-based catalysts. Therefore, cost-effective hydrolysis of NaB3H8 is possible …

Show Us Your (Carbon Nanotube Artificial) Muscles!, Geoffrey M. Spinks

Australian Institute for Innovative Materials - Papers

The idea of doctors deploying miniscule robots in your body to diagnose and treat medical conditions is closer to reality today with the development of artificial muscles small and strong enough to push such tiny "nano-bots" along.

Dithienothiophene (Dtt)-Based Dyes For Dye-Sensitized Solar Cells: Synthesis Of 2,6-Dibromo-Dtt, Tae-Hyuk Kwon, Vanessa Armel, Andrew Nattestad, Douglas R. Macfarlane, Udo Bach, Samuel J. Lind, Keith C. Gordon, Weihua Tang, David J. Jones, Andrew Holmes

Australian Institute for Innovative Materials - Papers

A one-pot synthesis of 2,6-dibromodithieno[3,2-b;2′,3′-d]thiophene (dibromo-DTT, 4) was developed. A key step was bromodecarboxylation of DTT-2,6-dicarboxylic acid, obtained by saponification of the diester 1. The donor-acceptor dye DAHTDTT (13), based on a central 2,6-bis[2′-(3′-hexylthienyl)]dithieno[3,2-b;2′,3′-d]thiophene core (9), was prepared and incorporated in a dye-sensitized solar cell (DSC), which exhibited an energy conversion efficiency of 7.3% with Voc of 697 mV, Jsc of 14.4 mA/cm2, and ff of 0.73 at 1 sun.

Oxidative Acetylenic Coupling Reactions As A Surface Chemistry Tool, Simone Ciampi, Michael James, Nadim A. Darwish, Erwann Luais, Bin Guan, Jason Brian Harper, J Justin Gooding

Australian Institute for Innovative Materials - Papers

A novel method to prepare redox monolayers on silicon electrodes has been developed that employs CuI-catalyzed oxidative acetylenic coupling reactions for molecular electronic type applications. As the first case study, ethynylferrocene was covalently immobilized onto an acetylene-terminated monolayer on a Si(100) surface to give a 1,3-diyne (CC-CC-) linked redox assembly. The derivatization process requires no protection/de-protection steps, nor activation procedures. The effect of the conjugated diyne linkage on the rate of electron transfer between tethered ferrocenyl units and the silicon electrode is benchmarked against well-established "click" products (i.e. 1,2,3-triazole linkage). The surfaces, after each step, are characterized thoroughly using X-ray …

The Molecular Level Modification Of Surfaces: From Self-Assembled Monolayers To Complex Molecular Assemblies, J Justin Gooding, Simone Ciampi

Australian Institute for Innovative Materials - Papers

The modification of surfaces with self-assembled monolayers (SAMs) containing multiple different molecules, or containing molecules with multiple different functional components, or both, has become increasingly popular over the last two decades. This explosion of interest is primarily related to the ability to control the modification of interfaces with something approaching molecular level control and to the ability to characterise the molecular constructs by which the surface is modified. Over this time the level of sophistication of molecular constructs, and the level of knowledge related to how to fabricate molecular constructs on surfaces have advanced enormously. This critical review aims to …

Molecular-Beam Epitaxy And Robust Superconductivity Of Stoichiometric Fese Crystalline Films On Bilayer Graphene, Canli Song, Yi-Lin Wang, Yeping Jiang, Zhi Li, Lili Wang, Ke He, Xi Chen, Xu-Cun Ma, Qi-Kun Xue

Australian Institute for Innovative Materials - Papers

We report on molecular beam epitaxy growth of stoichiometric and superconducting FeSe crystalline thin films on double-layer graphene. Layer-by-layer growth of high-quality films has been achieved in a well-controlled manner by using Se-rich condition, which allow us to investigate the thickness-dependent superconductivity of FeSe. In situ low-temperature scanning tunneling spectra reveal that the local superconducting gap in the quasiparticle density of states is visible down to two triple layers for the minimum measurement temperature of 2.2 K, and that the transition temperature Tc scales inversely with film thickness.

Block-Copolymer-Assisted Synthesis Of Hydroxyapatite Nanoparticles With High Surface Area And Uniform Size, Yu Huang, Masataka Imura, Yoshihiro Nemoto, Chao Hung Cheng, Yusuke Yamauchi

Australian Institute for Innovative Materials - Papers

We report the synthesis of hydroxyapatite nanoparticles (HANPs) by the coprecipitation method using calcium D-gluconate and potassium hydrogen phosphate as the sources of calcium and phosphate ions, respectively, and the triblock copolymer F127 as a stabilizer. The HANPs were characterized using scanning electron microscopy, x-ray diffraction, and nitrogen adsorption/desorption isotherms. Removal of F127 by solvent extraction or calcination alters the structure of HANPs. The solvent-extracted HANPs were single crystals with their 〈001〉 axis oriented along the rod axis of the HANP, whereas the calcined HANPs contained two crystal phases that resulted in a spherical morphology. The calcined HANPs had much …

Electromechanical Properties Of Pb (In1/2nb1/2) O3-Pb (Mg1/3nb2/3) O3-Pbtio3 Single Crystals, Fei Li, Shujun Zhang, Dabin Lin, Jun Luo, Zhuo Xu, Xiaoyong Wei, Thomas R. Shrout

Australian Institute for Innovative Materials - Papers

The Pb (In_1/2Nb_1/2) O₃–Pb (Mg_1/3Nb_2/3) O₃–PbTiO₃ (PIN-PMN-PT) crystals were studied as function of phase and orientation. The properties, including the Curie temperature T_C, ferroelectric-ferroelectric phase transition temperature T_R/O-T, coercive field, and piezoelectric/dielectric responses, were systematically investigated with respect to the composition of PIN-PMN-PT crystals. The Curie temperature T_C was found to increase from 160 to 220 °C with ferroelectric-ferroelectric phase transition temperature T_R-T and T_O-T being in the range of 120–105 °C and 105–50 °C, respectively. The piezoelectric activity of …