Physical Sciences and Mathematics Commons^™

Manipulation Of Nanoscale Domain Switching Using An Electron Beam With Omnidirectional Electric Field Distribution, Zi-Bin Chen, Xiaolin Wang, Simon Peter Ringer, Xiaozhou Liao

Australian Institute for Innovative Materials - Papers

Reversible ferroelectric domain (FD) manipulation with a high spatial resolution is critical for memory storage devices based on thin film ferroelectric materials. FD can be manipulated using techniques that apply heat, mechanical stress, or electric bias. However, these techniques have some drawbacks. Here we propose to use an electron beam with an omnidirectional electric field as a tool for erasable stable ferroelectric nanodomain manipulation. Our results suggest that local accumulation of charges contributes to the local electric field that determines domain configurations.

Trap-Assisted Transport And Non-Uniform Charge Distribution In Sulphur-Rich Pbs Colloidal Quantum Dot-Based Solar Cells With Selective Contacts, Victor Malgras, Guanran Zhang, Andrew Nattestad, Tracey M. Clarke, Attila J. Mozer, Yusuke Yamauchi, Jung Ho Kim

Australian Institute for Innovative Materials - Papers

This study reports evidences of dispersive transport in planar PbS colloidal quantum dots heterojunction-based devices as well as the effect of incorporating a MoO3 hole selective layer on the charge extraction behavior. Steady state and transient characterization techniques are employed to determine the complex recombination processes involved in such devices. The addition of a selective contact drastically improves the device efficiency up to 3.15 % (especially through the photocurrent and series resistance) and extends the overall charge lifetime by suppressing the main first-order recombination pathway observed in device without MoO3. The lifetime and mobility calculated for our sulphur-rich PbS-based devices …

A Simple Post-Hoc Method To Add Spatial Context To Predictive Species Distribution Models, Michael B. Ashcroft, Kristine O. French, Laurie A. Chisholm

Faculty of Science - Papers (Archive)

Methods to incorporate spatial context into species distribution models (SDMs) are underutilised, with predictions usually based only on environmental space and ignoring geographic space. The goals of this study were to demonstrate a relatively simple post-hoc method to include spatial context in SDMs and to quantify the improvement over purely niche-based models. The method involved producing a standard niche-based model using established techniques, such as Maxent, and then calculating the neighbourhood average of the model output in geographic space. In effect, we tested whether the spatially averaged model output was better at predicting species distributions than the raw model output. …

Fatty And Volatile Oils Of The Gypsywort Lycopus Europaeus L. And The Gaussian-Like Distribution Of Its Wax Alkanes, Niko Radulovic, Marija Denic, Zorica Stojanovic-Radic, Danielle Skropeta

Faculty of Science - Papers (Archive)

The detailed analyses of the volatile essential oil and lipid profiles of the aerial parts from the blooming and fruit-forming stages of both ripe and unripe fruit of Lycopus europaeus (Lamiaceae) are presented. Both of these profiles are distinguished by components with a restricted occurrence in the Plant Kingdom. These rare compounds include (E)-hotrienol in the volatiles, numerous unusual fatty acids (such as very long chain, odd-numbered and branched-chain) in the bound lipids and a high amount of iso- and anteiso-alkanes in the epicuticular waxes. Furthermore, a Gaussian-like distribution of the relative amounts of the epicuticular wax alkanes was observed. …

Flux Distribution In Fe-Based Superconducting Materials By Magneto-Optical Imaging, Zhi Wei Lin, Jian Guo Zhu, You Guang Guo, Xiaolin Wang, S X. Dou, Tom H. Johansen, Xun Shi, K Y. Choi

Australian Institute for Innovative Materials - Papers

"This paper presents the magnetic flux distributions in Fe-based superconducting materials including single crystal of Ba(Fe_1.9Ni_0.1)As₂ and Ba(Fe_1.8Co_0.2)As₂, as well as polycrystalline SmFeO_0.75F_0.2As by means of magneto-optical imaging (MOI) technique. The single crystals were grown out of FeAs flux while polycrystalline sample was grown by hot-press. A MOI film with in-plan magnetization was used to visualize flux distributions at the sample surface. A series of magneto-optical images was taken when the samples were zero-field cooled and field cooled. The flux behavior, including penetration into and …

Sources, Distribution, And Acidity Of Sulfate-Ammonium Aerosol In The Arctic In Winter-Spring, Jenny A. Fisher, Daniel J. Jacob, Q Wang, Roya Bahreini, C C. Carouge, M J. Cubison, Jack E. Dibb, Thomas Diehl, J L. Jimenez, E M. Leibensperger, Zifeng Lu, Marcel B.J Meinders, H. O T. Pye, Patricia K. Quinn, Sangeeta Sharma, David G. Streets, Aaron Van Donkelaar, R M. Yantosca

Faculty of Science - Papers (Archive)

We use GEOS-Chem chemical transport model simulations of sulfate–ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter–spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is …

How Well Do Predators Adjust To Climate-Mediated Shifts In Prey Distribution? A Study On Australian Water Pythons, Beata Ujvari, Rick Shine, Thomas Madsen

Faculty of Science - Papers (Archive)

Climate change can move the spatial location of resources critical for population viability, and a species resilience to such changes will depend upon its ability to flexibly shift its activities away from no-longer-suitable sites to exploit new opportunities. Intuition suggests that vagile predators should be able to track spatial shifts in prey availability, but our data on water pythons (Liasis fuscus) in tropical Australia suggest a less encouraging scenario. These pythons undergo regular long-range (to .10 km) seasonal migrations to follow flooding-induced migrations by their prey (native dusky rats, Rattus colletti ). However, when an extreme flooding event virtually eliminated …

Monitoring Intelligent Distribution Power Systems: A Power Quality Plan, Neil R. Browne, Timothy J. Browne, Sean T. Elphick

Faculty of Informatics - Papers (Archive)

Power system monitoring capabilities and requirements are evolving rapidly. The traditional monitoring framework in Australian distribution networks involves biannual readings of maximum demand at each distribution substation. As utilities respond to developments in metering and communications technology, automated collection and retrieval of quasi-real-time system data between substations and central repositories is now feasible. This gives network managers a significantly increased understanding of distribution network dynamic activity such as daily and seasonal load profiles. This leads to the increased ability of utilities to exploit metering data for power quality analysis purposes. This paper examines the scope for, and challenges associated with, …

Evidence For Specific Subunit Distribution And Interactions In The Quaternary Structure Of Α-Crystallin, Amie M. Morris, J Andrew Aquilina

Faculty of Science - Papers (Archive)

The quaternary structure of alpha-crystallin is dynamic, a property which has thwarted crystallographic efforts towards structural characterization. In this study, we have used collision-induced dissociation mass spectrometry to examine the architecture of the polydisperse assemblies of alpha-crystallin. For total alpha-crystallin isolated directly from fetal calf lens using size-based chromatography, the alpha B-crystallin subunit was found to be preferentially dissociated from the oligomers, despite being significantly less abundant overall than the alpha A-crystallin subunits. Furthermore, upon mixing molar equivalents of purified alpha A- and alpha B-crystallin, the levels of their dissociation were found to decrease and increase, respectively, with time. Interestingly …

Distribution Of Class 1 Integrons With Is26-Mediated Deletions In Their 3'-Conserved Segments In Escherichia Coli Of Human And Animal Origin., Fay E. Dawes, Alexander Kuzevski, Karl A Bettelheim, Michael A Hornitzky, Steven P Djordjevic, Mark J. Walker

Faculty of Science - Papers (Archive)

Class 1 integrons play a role in the emergence of multi-resistant bacteria by facilitating the recruitment of gene cassettes encoding antibiotic resistance genes. 512 E. coli strains sourced from humans (n = 202), animals (n = 304) and the environment (n = 6) were screened for the presence of the intI1 gene. In 31/79 integron positive E. coli strains, the gene cassette regions could not be PCR amplified using standard primers. DNA sequence analysis of 6 serologically diverse strains revealed atypical integrons harboured the dfrA5 cassette gene and only 24 bp of the integron 3'-conserved segment (CS) remained, due to …

A Multi-Scale Geospatial Study Of Wetlands Distribution And Agricultural Zones, And The Case Of India, N Nagabhatla, Rohan Wickramasuriya, N Prasad, Max Finlayson

Faculty of Science - Papers (Archive)

This paper highlights the global and the regional scale representation of wetlands ecosystems using geospatial tools and multiple data sets. At global scale, the Ramsar database is investigated for representation of the wetlands sites of international importance against the "global agricultural zones" derived from the thematic aggregation of Global Irrigated Area Map databases. The analysis of "Ramsar sites" under cultivation reflects the present trend in wetlands use for agriculture. The scenario is also compared with the historical pattern derived from Vavilov's food zones of 1926. Observed is an aggregate increase in cropped wetlands area from 25% (1926) to 43% (2006). …

Soil Geochemistry And Pathfinder Element Distribution Associated With The Hillgrove Antimony-Gold-Tungsten Deposit, New England Orogen, Nsw, R Ellsmore, Solomon Buckman, C Simpson

Faculty of Science - Papers (Archive)

No abstract provided.

Support Of Distribution System Using Distributed Wind And Pv Systems, Kai Zou, Ashish P. Agalgaonkar, Kashem Muttaqi, Sarath Perera, N Browne

Faculty of Informatics - Papers (Archive)

The application of renewable distributed generation (DG) could be considered as an alternative approach for distribution system expansion planning not only to reduce power loss and carbon emission, but also to improve system voltage profile. This paper investigates technical aspects relatedto voltage support and loss reduction in distribution systems with distributed wind and solar generation. The probabilistic wind, solar, and load models have been developed in order to address uncertain nature of wind speed, solar radiation, and load demand. Investigations have been carried out using Monte Carlo based probabilistic load flow analysis to estimate the probability distributions of system state …

Optimisation Of Distributed Generation Units And Shunt Capacitors For Economic Operation Of Distribution Systems, Kai Zou, Sarath Perera, Kashem Muttaqi, Ashish P. Agalgaonkar

Faculty of Informatics - Papers (Archive)

The integration of Distributed Generation (DG) units and shunt capacitors can be considered as an alternative approach for distribution system expansion planning not only to improve power supply quality and reliability, but also to defer major system updates. In this paper, the techno-economic issues of distribution system expansion planning with optimal sizing and siting of DG units and shunt capacitors are addressed. The minimisation of overall investment cost with the integration of DG units and shunt capacitors is assessed with the consideration of supply quality, reliability and energy loss. A new planning methodology by using Particle Swarm Optimisation (PSO) is …

Saidi Minimization Of A Remote Distribution Feeder, Kai Zou, Wickramaarachchi W. Keerthipala, Sarath Perera

Faculty of Informatics - Papers (Archive)

Distribution system reliability assessment is an important part of distribution system operation and planning. This paper presents some approaches taken to minimize the SAIDI (System Average Interruption Duration Index) for a remote distribution feeder in an 11kV distribution system. Resulting from unavailability of alternative backup supplies from the other adjacent feeders, distributed generators (DG) can be used as backup supplies in this case. Coordinating distribution automation (DA) system with DGs, the restoration area can be made larger and the outage time can be shorter, consequently, the distribution system reliability can be improved significantly. In this paper, factors affecting SAIDI are …

Effect Of Protein Stabilization On Charge State Distribution In Positive- And Negative Ion Electrospray Ionization Mass Spectra, Stephen J. Watt, Margaret Sheil, Jennifer L. Beck, Pavel Prosselkov, Gottfried Otting, Nicholas E. Dixon

Faculty of Science - Papers (Archive)

Changes in protein conformation are thought to alter charge state distributions observed in electrospray ionization mass spectra (ESI-MS) of proteins. In most cases, this has been demonstrated by unfolding proteins through acidification of the solution. This methodology changes the properties of the solvent so that changes in the ESI-MS charge envelopes from conformational changes are difficult to separate from the effects of changing solvent on the ionization process. A novel strategy is presented enabling comparison of ESI mass spectra of a folded and partially unfolded protein of the same amino acid sequence subjected to the same experimental protocols and conditions. …

Impact Of Data Uncertainty On The Spatio-Temporal Distribution Of Australian Cyclones, 1906-2006, Marjetta L. Puotinen

Faculty of Science - Papers (Archive)

Tropical cyclones (known elsewhere as hurricanes or typhoons) regularly track through Australia’s northern coastal regions (Figure 1).

Data documenting the basic characteristics of cyclones in the Australian region is available from the Bureau of Meteorology (BOM) as early as 1906. This data set (freely available in ASCII format at http://www.bom.gov.au) records some 41 attributes (most of which are not complete for the entire time series) for 22,645 individual cyclone eye positions. Because cyclones can cause considerable impact to both marine and terrestrial environments, data sets such as this are widely used to reconstruct past cyclone conditions (for example, see Berz …

Harmonic Impact Of Photovoltaic Inverters On Low Voltage Distribution Systems, Ahmed Latheef, D A. Robinson, Victor J. Gosbell, Victor W. Smith

Faculty of Informatics - Papers (Archive)

The number of installations of photovoltaic solar panels and associated inverter systems within residential premises is increasing. As these systems incorporate a power electronics front end, they will have an influence on the quality of supply in regards to voltage harmonics. This paper investigates the harmonic impact on an LV distribution feeder due to the installation of residential type grid connected photovoltaic inverter systems. To undertake the study an aggregated current source model is proposed for the photovoltaic inverter systems based on measurement data from available literature and the relevant international standards. A typical LV distribution feeder including load arrangements …

Force Distribution For Double-Walled Carbon Nanotubes, Duangkamon Baowan, James M. Hill

Faculty of Informatics - Papers (Archive)

Advances in technology have led to the creation of many nano-scale devices and carbon nanotubes are representative materials to construct these devices. Double-walled carbon nanotubes with the inner tube oscillating can be used as gigahertz oscillators and form the basis of possible nano-electronic devices. Such gigahertz oscillating devices made from carbon nanotubes might be instrumental in the micro-computer industry, which is predominantly based on electron transport phenomena. There are many experiments and molecular dynamics simulations which show that a wave is generated on the outer cylinder by the oscillation of the carbon nanotubes and that the frequency of this wave …

Influence Of The Iron Sheath On The Local Supercurrent Distribution In Mgb2 Wires, Marie Roussel, Alexey V. Pan, Sihai Zhou, S X. Dou

Australian Institute for Innovative Materials - Papers

The magnetic behavior of iron sheathed magnesium diboride (MgB₂) wires was investigated. Global magnetization measurements have shown unusual critical current density variations compare to a superconductor with no magnetic environment. Local quantitative studies, through MO images, are linked to these global magnetization measurements in order to better understand the observed results. It is shown that the current distribution is affected by the soft magnetic sheath interacting with the superconducting core.

Harmonic Planning Levels For Australian Distribution Systems, Victor J. Gosbell, Victor W. Smith, D A. Robinson, W Miller

Faculty of Informatics - Papers (Archive)

A modelling technique is developed for determining the harmonic voltage distribution across a distribution system when there is an equitable distribution of harmonic emission. The harmonic voltages at the 132kV and 415V levels are fixed to values based on IEC Compatibility and Planning Levels and the intermediate voltages determined. Studies are made of six systems, typical of Australian distribution practice, to examine the effect of choice of voltage level and system parameters over the harmonic range of 2-40. Based on the study, harmonic Planning Levels are recommended for application to Australian distribution systems.

A Study Of Continuous Pq Disturbance Levels In Mv/Lv Distribution Systems, Victor J. Gosbell, D A. Robinson

Faculty of Informatics - Papers (Archive)

Distribution Network Service Providers need to be aware of the general variation of PQ disturbances across their network, from the sites as diverse as the MV bus bar of a zone substation, the end of a MV feeder, and at the near and far ends of LV mains. This paper develops an understanding of PQ variations across such a system from survey results correlated with approximate analysis used to assign a PQ disturbance ranking to each site. The work will concentrate on continuous PQ disturbances, defined as those due to load current effects, for example voltage deviations, unbalance, fluctuations and …

The Estimation Of Continuous Pq Disturbance Levels In Distribution Systems, Victor J. Gosbell, D A. Robinson

Faculty of Informatics - Papers (Archive)

A simple method is given for estimating the continuous PQ disturbance level at a site. It is based on determining a "Voltage Distortion Increment" (VDI) for each segment of the network and then adding the VDIs from a given site back to an upstream site where levels are taken to be zero. The VDI is conveniently expressible in the form of S(MVA) times length (km), where "length" correspond to the physical length in the case of MV overhead lines and an equivalent length for other components. The method is verified by a comparison with field survey data. The voltage distortion …

Evaluating The Optimal Probability Distribution For Steganography Under Zero-Error Conditions, Gareth Brisbane, Reihaneh Safavi-Naini, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

Information hiding can be performed under the guise of a digital image. We consider the following scenario: Alice and Bob share an image and would like to use it as a cover image to communicate a message m. We are interested in answering two questions: What is the maximum amount of information that can be sent for a given level of degradation to an image? and How can this level of efficiency be achieved in practice? We require the recovered message to be the same as the embedded one. Our model begins with Alice compressing a message to obtain a …

Harmonic Survey Of An Mv Distribution System, Victor J. Gosbell, Damian Mannix, D A. Robinson, Sarath Perera

Faculty of Informatics - Papers (Archive)

The harmonic survey of a medium voltage distribution system involves three major aspects: (i) the choice of harmonic monitor, (ii) the choice of monitoring site, (iii) processing and presentation of results. As well as a discussion of the methodology for these aspects, the paper will discuss the harmonic levels measured, the minimum survey requirements for finding useful data and the harmonic parameters of residential, commercial and industrial loads.

Differentiate And Make Waves, R. Nillsen

Faculty of Informatics - Papers (Archive)

In 1972 Gary Meisters and Wolfgang Schmidt showed that if the Fourier coefficient of a function is zero at the origin, then the function is a sum of three first order differences. They deduced from this that every translation invariant linear form on the space of square integrable functions on the circle group is automatically continuous. Their results were subsequently developed by the author for the case of n-dimensional Euclidean space (Lectures Notes in Mathematics, vol. 1586, Springer-Verlag,1994). The present paper gives an exposition of some of the ideas in this work, with the aim of minimising the technicalities. In …