Physical Sciences and Mathematics Commons^™

Thermal And Viscous Boundary Layers In Turbulent Rayleigh–Bénard Convection, Janet Scheel, E. Kim, K. White

Janet D. Scheel

We present the results from numerical simulations of turbulent Rayleigh–Bénard convection for an aspect ratio (diameter/height) of 1.0, Prandtl numbers of 0.4 and 0.7, and Rayleigh numbers from $1\ensuremath{\times} 1{0}^{5} $ to $1\ensuremath{\times} 1{0}^{9} $. Detailed measurements of the thermal and viscous boundary layer profiles are made and compared to experimental and theoretical (Prandtl–Blasius) results. We find that the thermal boundary layer profiles disagree by more than 10 % when scaled with the similarity variable (boundary layer thickness) and likewise disagree with the Prandtl–Blasius results. In contrast, the viscous boundary profiles collapse well and do agree (within 10 %) with …

Effects Of Electrostatic Correlations On Electrokinetic Phenomena, Brian Storey, Martin Bazant

Brian Storey

The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper considers situations, such as concentrated electrolytes, multivalent electrolytes, or solvent-free ionic liquids, where the mean-field approximation breaks down. A fourth-order modified Poisson equation is developed that captures the essential features in a simple continuum framework. The model is derived as a gradient approximation for nonlocal electrostatics of interacting effective charges, where the permittivity becomes a differential operator, scaled by a correlation length. The theory is able to capture …

Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. Casse, W. Lu, Y. Huang, E. Gultepe, L. Menon, S. Sridhar

Srinivas Sridhar

Super-resolution imaging beyond Abbe's diffraction limit can be achieved by utilizing an optical medium or "metamaterial" that can either amplify or transport the decaying near-field evanescent waves that carry subwavelength features of objects. Earlier approaches at optical frequencies mostly utilized the amplification of evanescent waves in thin metallic films or metal-dielectric multilayers, but were restricted to very small thicknesses (⪡λ, wavelength) and accordingly short object-image distances, due to losses in the material. Here, we present an experimental demonstration of super-resolution imaging by a low-loss three-dimensional metamaterial nanolens consisting of aligned gold nanowires embedded in a porous alumina matrix. This composite …

Building Capability For Disaster Resilience, Lynn Crawford, Craig Langston, Bhishna Bajracharya

Bhishna Bajracharya

All levels of government recognise the widespread devastation of communities by natural or other disasters. They have responded with emergency management arrangements and policies to enhance government and community capacity to anticipate, withstand and recover from disastrous events. Although the construction industry has a significant role to play, particularly in recovery and reconstruction, it has not generally been considered as a key stakeholder in building capability for disaster resilience. One barrier to more active involvement of the construction industry in disaster response and management is that traditional methods of construction project management have been criticised as too time consuming and …

Planning And Design Of Master-Planned Communities For Healthy Living, Bhishna Bajracharya, Linda Too

Bhishna Bajracharya

Due to growing health concerns linked to inactive living, a number of new master-planned communities in South East Queensland are creating supportive environments for physical activities. Varsity Lakes in Gold Coast is an example of such community which provides both infrastructures and programs to encourage active living. The objective of the paper is to examine the relationship between built environment and healthy communities through a review of current literature. Synthesising these findings, a conceptual framework is developed for supporting active and healthy living in master-planned communities. The three key factors are 1) place; 2) program and 3) partnership. This framework …

Planning And Design Of Master-Planned Communities For Healthy Living, Bhishna Bajracharya, Linda Too

Linda Too

Due to growing health concerns linked to inactive living, a number of new master-planned communities in South East Queensland are creating supportive environments for physical activities. Varsity Lakes in Gold Coast is an example of such community which provides both infrastructures and programs to encourage active living. The objective of the paper is to examine the relationship between built environment and healthy communities through a review of current literature. Synthesising these findings, a conceptual framework is developed for supporting active and healthy living in master-planned communities. The three key factors are 1) place; 2) program and 3) partnership. This framework …

Is The Notion Of Divisible On-Line/Off-Line Signatures Stronger Than On-Line/Off-Line Signatures?, Willy Susilo, Yi Mu, Man Ho Allen Au

Dr Man Ho Allen Au

On-line/Off-line signatures are useful in many applications where the signer has a very limited response time once the message is presented. The idea is to perform the signing process in two phases. The first phase is performed off-line before the message to be signed is available and the second phase is performed on-line after the message to be signed is provided. Recently, in CT-RSA 2009, Gao et al. made a very interesting observation that most of the existing schemes possess the following structure. In the off-line phase, a partial signature, called the off-line token is computed first. Upon completion of …

Electronic Cash With Anonymous User Suspension, Man Ho Au, Willy Susilo, Yi Mu

Dr Man Ho Allen Au

Electronic cash (E-cash) is the digital counterpart of cash payment. They allow users to spend anonymously unless they “double spend” their electronic coins. However, it is not possible to prevent users from misbehaving under some other subjective definitions of misbehavior, such as money laundering. One solution is to incorporate a trusted third party (TTP), which, upon complaint, uses its power to deanonymize the suspected user. This solution, known as fair e-cash, is not fully satisfactory since additional measure has to be taken to stop misbehaving users from further abusing the system after they have been identified. We present a e-cash …

Mindscapes And Landscapes: Hayek And Simon On Cognitive Extension, Leslie Marsh

Leslie Marsh

Hayek’s and Simon’s social externalism runs on a shared presupposition: mind is constrained in its computational capacity to detect, harvest, and assimilate “data” generated by the infinitely fine-grained and perpetually dynamic characteristic of experience in complex social environments. For Hayek, mind and sociality are co-evolved spontaneous orders, allowing little or no prospect of comprehensive explanation, trapped in a hermeneutically sealed, i.e. inescapably context bound, eco-system. For Simon, it is the simplicity of mind that is the bottleneck, overwhelmed by the ambient complexity of the environmental. Since on Simon’s account complexity is unidirectional, Simon is far more ebullient about the prospects …

Let's Come Together On Data Science, Jennifer Priestley

Jennifer L. Priestley

We've all read the articles and blogs. Many of us have experienced the issues directly -- the demand for deep analytical skills is outpacing the supply. As evidence of this, in a period of economic slowdown, where we read that 50 percent of college graduates can't get a job, college graduates with degrees remotely aligned with applied analytics have multiple offers in advance of graduation. Academic training in applied (versus theoretical) statistics is helpful -- and mitigates some of this talent gap at the entry level. Nonetheless, we all know it's insufficient to meet the growing demand for what we …

Nearest Neighbor Methods Applied To Dune Field Organization: The Coral Pink Sand Dunes, Kane County, Utah, Usa, David Wilkins, Richard Ford

David E. Wilkins

Dune fields have recently come to be recognized as self-organizing systems that can be seen progressing from states of disorganization or randomness to uniformity. Dune systems can be highly sensitive to changes in factors, such as climate and sediment transport, that determine system state. Changes in climate and sediment state can take time to work their way through a dune system; this, in turn, leads to spatial heterogeneity in dune field organization. Using the Coral Pink Sand Dunes in southern Utah as a model, this study tests nearest neighbor analysis adapted as a method to objectively identify and characterize differences …

Palaeolake Shoreline Sequencing Using Ground Penetrating Radar: Lake Alvord, Oregon, And Nevada, David Wilkins, William Clement

David E. Wilkins

Field, map, and aerial photoreconnaissance in the Lake Alvord basin has focused on identifying late Pleistocene depositional shoreline features (e.g., tombolos, spits, barriers). Features in different areas of the basin are well defined, and their spatial extents are easily mapped; however, absolute---or even relative-ages of shoreline features are not clear. Ground penetrating radar (GPR) was used to distinguish between intermediate and highstand stage shorelines during what is thought to have been the latest Pleistocene, threshold-controlled lake cycle. Radar transects of 280 and 600 m imaged a spit and a baymouth barrier at sites in the northeastern quadrant of the basin …

36 Degrees Step Size Of Proton-Driven C-Ring Rotation In Fof1-Atp Synthase, Monika Düser, Nawid Zarrabi, Daniel Cipriano, Stefan Ernst, Gary Glick, Stanley Dunn, Michael Börsch

Stanley D Dunn

Synthesis of adenosine triphosphate ATP, the 'biological energy currency', is accomplished by F(o)F(1)-ATP synthase. In the plasma membrane of Escherichia coli, proton-driven rotation of a ring of 10 c subunits in the F(o) motor powers catalysis in the F(1) motor. Although F(1) uses 120 degrees stepping during ATP synthesis, models of F(o) predict either an incremental rotation of c subunits in 36 degrees steps or larger step sizes comprising several fast substeps. Using single-molecule fluorescence resonance energy transfer, we provide the first experimental determination of a 36 degrees sequential stepping mode of the c-ring during ATP synthesis.

A Dipolar Coupling Based Strategy For Simultaneous Resonance Assignment And Structure Determination Of Protein Backbones, Fang Tian, Homayoun Valafar, James Prestegard

Homayoun Valafar

A new approach for simultaneous protein backbone resonance assignment and structure determination by NMR is introduced. This approach relies on recent advances in high-resolution NMR spectroscopy that allow observation of anisotropic interactions, such as dipolar couplings, from proteins partially aligned in field ordered media. Residual dipolar couplings are used for both geometric information and a filter in the assembly of residues in a sequential manner. Experimental data were collected in less than one week on a small redox protein, rubredoxin, that was 15N enriched but not enriched above 1% natural abundance in 13C. Given the acceleration possible with partial 13C …

Re-Introduction Of Transmembrane Serine Residues Reduce The Minimum Pore Diameter Of Channelrhodopsin-2, Robert Dempski, Ryan Richards

Robert E. Dempski

Channelrhodopsin-2 (ChR2) is a microbial-type rhodopsin found in the green algae Chlamydomonas reinhardtii. Under physiological conditions, ChR2 is an inwardly rectifying cation channel that permeates a wide range of mono- and divalent cations. Although this protein shares a high sequence homology with other microbial-type rhodopsins, which are ion pumps, ChR2 is an ion channel. A sequence alignment of ChR2 with bacteriorhodopsin, a proton pump, reveals that ChR2 lacks specific motifs and residues, such as serine and threonine, known to contribute to non-covalent interactions within transmembrane domains. We hypothesized that reintroduction of the eight transmembrane serine residues present in bacteriorhodopsin, but …

Resource Allocation In Dynamic Environments, Jeffrey Hansen, Scott Hissam, Craig Meyers, Gabriel Moreno, Daniel Plakosh, Joe Seibel, Lutz Wrage

Gabriel A. Moreno

This technical report examines two challenges related to resource allocation that can negatively affect system operation in a dynamic environment, where warfighter needs for resources, resource availability, environmental effects, and mission conditions can change from moment to moment. The first challenge occurs when warfighters overstate their individual needs of a shared resource, leading to inefficient allocation. Overstatement may bring local optimization; however, it can cause global inefficiencies that result in a detriment to overall mission success. This challenge is addressed by using computational mechanism design, more specifically, the dynamic Vickrey-Clark-Groves allocation mechanism. The second challenge involves resource availability that may …

Structural Insights Into Neuronal K+ Channel-Calmodulin Complexes, Karen Mruk, Shivender Shandilya, Robert Blaustein, Celia Schiffer, William Kobertz

Celia A. Schiffer

Calmodulin (CaM) is a ubiquitous intracellular calcium sensor that directly binds to and modulates a wide variety of ion channels. Despite the large repository of high-resolution structures of CaM bound to peptide fragments derived from ion channels, there is no structural information about CaM bound to a fully folded ion channel at the plasma membrane. To determine the location of CaM docked to a functioning KCNQ K(+) channel, we developed an intracellular tethered blocker approach to measure distances between CaM residues and the ion-conducting pathway. Combining these distance restraints with structural bioinformatics, we generated an archetypal quaternary structural model of …

Greedy Approximation Of Kernel Pca By Minimizing The Mapping Error, Peng Cheng, Wanqing Li, Philip Ogunbona

Professor Philip Ogunbona

In this paper we propose a new kernel PCA (KPCA) speed-up algorithm that aims to find a reduced KPCA to approximate the kernel mapping. The algorithm works by greedily choosing a subset of the training samples that minimizes the mean square error of the kernel mapping between the original KPCA and the reduced KPCA. Experimental results have shown that the proposed algorithm is more efficient in computation and effective with lower mapping errors than previous algorithms.

Detecting Humans Under Occlusion Using Variational Mean Field Method, Duc Thanh Nguyen, Philip Ogunbona, Wanqing Li

Professor Philip Ogunbona

This paper proposes a human detection method using variational mean field approximation for occlusion reasoning. In the method, parts of human objects are detected individually using template matching. Initial detection hypotheses with spatial layout information are represented in a graphical model and refined through a Bayesian estimation. In this paper, mean field method is employed for such an estimation. The proposed method was evaluated on the popular CAVIAR-INRIA dataset. Experimental results show that the proposed algorithm is able to detect humans in severe occlusion within reasonable processing time.

On The Step Response Of The Dct, Jim Andrew, Philip Ogunbona

Professor Philip Ogunbona

We show that the discrete cosine transform (DCT) is the best orthogonal transform, in terms of energy packing efficiency, for coding input steps of uniformly distributed random phase. Over sufficiently small block sizes, edges in an image can be modeled as such step inputs. This characteristic of the DCT, coupled with its high energy packing efficiency for highly correlated data, helps explain the impressive performance of the DCT for image compression.

On The Combination Of Local Texture And Global Structure For Food Classification, Zhimin Zong, Duc Thanh Nguyen, Philip Ogunbona, Wanqing Li

Professor Philip Ogunbona

This paper proposes a food image classification method using local textural patterns and their global structure to describe the food image. In this paper, a visual codebook of local textural patterns is created by employing Scale Invariant Feature Transformation (SIFT) interest point detector with the Local Binary Pattern (LBP) feature. In addition to describing the food image using local texture, the global structure of the food object is represented as the spatial distribution of the local textural structures and encoded using shape context. We evaluated the proposed method on the Pittsburgh Fast-Food Image (PFI) dataset. Experimental results showed that the …

Dating Of Major Normal Fault Systems Using Thermochronology: An Example From The Raft River Detachment, Basin And Range, Western United States, Michael Wells, Lawrence Snee, Ann Blythe

Ann Blythe

Application of thermochronological techniques to major normal fault systems can resolve the timing of initiation and duration of extension, rates of motion on detachment faults, timing of ductile mylonite formation and passage of rocks through the crystal-plastic to brittle transition, and multiple events of extensional unroofing. Here we determine the above for the top-to-the-east Raft River detachment fault and shear zone by study of spatial gradients in 40Ar/39Ar and fission track cooling ages of footwall rocks and cooling histories and by comparison of cooling histories with deformation temperatures. Mica 40Ar/39Ar cooling ages indicate that extension-related cooling began at ∼25–20 Ma, …

Adaptation To Hard-Object Feeding In Sea Otters And Hominins, Paul Constantino, James Lee, Dylan Morris, Peter Lucas, Adam Hartstone-Rose, Wah-Keat Lee, Nathaniel Dominy, Andrew Cunningham, Mark Wagner, Brian Lawn

Paul J. Constantino

The large, bunodont postcanine teeth in living sea otters (Enhydra lutris) have been likened to those of certain fossil hominins, particularly the ’robust’ australopiths (genus Paranthropus). We examine this evolutionary convergence by conducting fracture experiments on extracted molar teeth of sea otters and modern humans (Homo sapiens) to determine how load-bearing capacity relates to tooth morphology and enamel material properties. In situ optical microscopy and x-ray imaging during simulated occlusal loading reveal the nature of the fracture patterns. Explicit fracture relations are used to analyze the data and to extrapolate the results from humans to earlier hominins. It is shown …

Lifespan Theorem For Simple Constrained Surface Diffusion Flows, Glen Wheeler

Dr Glen Wheeler

We consider closed immersed hypersurfaces in R3 and R4 evolving by a special class of constrainedsurfacediffusionflows. This class of constrainedflows includes the classical surfacediffusionflow. In this paper we present a LifespanTheoremfor these flows, which gives a positive lower bound on the time for which a smooth solution exists, and a small upper bound on the total curvature during this time. The hypothesis of the theorem is that the surface is not already singular in terms of concentration of curvature. This turns out to be a deep property of the initial manifold, as the lower bound on maximal time obtained depends …

Starcraft Ii In-Game Action Lists, Wei Gong, Ee Peng Lim, Palakorn Achananuparp, Feida Zhu, David Lo, Freddy Chua

David LO

1732 event logs of actions performed by players in Starcraft II public replays downloaded from GameReplays.org.

The Data Set consists of 1732 log files (Size: 55 MB) compressed into a Zip archive (Size: 9.3 MB).

Using Web 2.0 Technologies For Collaborative Learning In Distance Education- Case Studies From An Australian University, Kristin Den Exter, Stephen Rowe, William Boyd, David Lloyd

Dr Kristin den Exter

This paper explores the use of Web 2.0 technologies for collaborative learning in a higher education context. A review of the literature exploring the strengths and weaknesses of Web 2.0 technology is presented, and a conceptual model of a Web 2.0 community of inquiry is introduced. Two Australian case studies are described, with an ex-poste evaluation of the use of Web 2.0 tools. Conclusions are drawn as to the potential for the use of Web 2.0 tools for collaborative e-learning in higher education. In particular, design and integration of Web 2.0 tools should be closely related to curriculum intent and …

A Statistical Model To Forecast Short-Term Atlantic Hurricane Intensity, Kevin Law, Jay Hobgood

Kevin Law

An alternative 24-h statistical hurricane intensity model is presented and verified for 13 hurricanes during the 2004–05 seasons. The model uses a new method involving a discriminant function analysis (DFA) to select from a collection of multiple regression equations. These equations were developed to predict the future 24-h wind speed increase and the 24-h pressure drop that were constructed from a dataset of 103 hurricanes from 1988 to 2003 that utilized 25 predictors of rapid intensification. The accuracy of the 24-h wind speed increase models was tested and compared with the official National Hurricane Center (NHC) 24-h intensity forecasts, which …

The Impact Of Oceanic Heat Content On The Rapid Intensification Of Atlantic Hurricanes, Kevin Law

Kevin Law

With the increased infrastructure and amount of people living along the United States coastline, it is imperative to improve the accuracy of Atlantic hurricane intensity forecasts. Over the last 10 years, there have been many Atlantic hurricanes, including Hurricanes Katrina and Charley that surprised many forecasters with their rapid intensification and power. The rapid intensification of tropical cyclones is the most serious aspect, when it comes to forecasting. It is generally accepted that sufficient surface ocean temperatures (approximately 26°C) are needed to produce and sustain tropical cyclone formation. However, the sea-surface temperature (SST) has shown not to be critical in …

Characterisation And Modelling Of Hts Coils, Christopher Cook, T Hardono

Christopher Cook

Recent efforts on manufacturing high temperature superconductors (HTS) have resulted in the production of coils which promise significant benefits for power engineering applications. Losses in two HTS pancake coils carrying AC current are measured and the results are analysed. It is shown that a thin pancake coil with relatively large diameter can be treated as straight tapes arranged in a face-to-face stack with the spacing between the tapes chosen to be relatively small. Losses in the tapes become those predicted using Norris's equation for an infinite slab.

Design Of A High Temperature Superconductor Magnetic Energy Storage Systems, R L Causley, Christopher Cook, Steve Gower

Christopher Cook

The University of Wollongong (UoW) has received funding for the research and development of a 20 kJ high temperature superconducting magnetic energy storage device (HTS SMES). This SMES will be operated at 25 K in contrast to most existing HTS designs, which operate at 77K. This paper includes a literature review of the current technology for the configuration of the SMES coil and a summary of the work done at UoW to date. Solenoidal and toroidal coils designs are compared to determine which will provide the required level of energy stored for a minimum superconductor and device volume. The design …