Saleem S.,University of QueenslandQLD |
Gallagher M.,University of QueenslandQLD
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2017
The size, scope and variety of the experimental analyses of metaheuristics has increased in recent years, aiming to develop new procedures and techniques to improve our understanding of optimization algorithms and problems. In this paper, we compare particle swarm optimization and differential evolution on a set of real-world clustering problems. Generally, experimental comparisons focus on presenting a statistical summary of algorithm performance, however this hides valuable information about the algorithm behaviour on the problems in question. Instead, we take an exploratory approach, focussing on extracting deeper insights and understanding from the experimental results data. We make progress on understanding the fitness landscapes of the set of clustering problems, as well as analysing current and previous experimental results for algorithms applied to these problems. Consequently, the paper makes two contributions: (a) Advancing our understanding of what factors make this set of problem instances easy or hard for given algorithms; (b) Demonstrating the need to be careful in experimental evaluations and that better insights can be obtained with exploratory analysis. © Springer International Publishing AG 2017.
Gard M.,Southern Cross University of Australia |
Gard M.,University of QueenslandQLD
Sport, Education and Society | Year: 2015
As the discussant of this special issue, I focus on two related ideas: choice and self-interest. First, I explore the idea of choice and its relevance within research that concerns itself with a heavily loaded concept like ‘social justice’. My proposal here is that future scholarship that explores the consequences of privatised health and physical education (HPE) might at least factor in choice as one from a list of competing priorities. For example, does greater choice trump concerns about equity? Is it possible that increasing choice is one of the ways in which important social policy outcomes might be achieved? Second, like a number of the papers in this special issue, I argue that the privatisation of HPE portends significant changes in the way knowledge is produced, consumed and evaluated. Through all of this, old ideas about the role of the academic are increasingly salient. But rather than limiting our critical gaze to the purveyors of privatised HPE, I suggest that financial self-interest is only one kind of self-interest amongst many others, each of which deserve our attention. © 2014, © 2014 Taylor & Francis.
Simula T.,Monash University |
Davis M.J.,University of QueenslandQLD |
Helmerson K.,Monash University
Physical Review Letters | Year: 2014
We study the relaxation dynamics of an isolated zero temperature quasi-two-dimensional superfluid Bose-Einstein condensate that is imprinted with a spatially random distribution of quantum vortices. Following a period of vortex annihilation the remaining vortices self-organize into two macroscopic coherent "Onsager vortex" clusters that are stable indefinitely - despite the absence of driving or external dissipation in the dynamics. We demonstrate that this occurs due to a novel physical mechanism - the evaporative heating of the vortices - that results in a negative-temperature phase transition in the vortex degrees of freedom. At the end of our simulations the system is trapped in a nonthermal state. Our computational results provide a pathway to observing Onsager vortex states in a superfluid Bose gas. © 2014 American Physical Society.
Lai M.H.,University of Hong Kong |
Ho J.C.M.,University of QueenslandQLD
Journal of Constructional Steel Research | Year: 2015
Nowadays reinforced concrete (RC) columns are commonly adopted in tall building structures. One of its associated problems is that the transverse steel cannot confine the concrete cover and has limited effect on the ductility improvement, particularly of those made of high-strength concrete (HSC). Therefore, there is usually a maximum limit of concrete strength that can be used. To further push up this limit, concrete-filled-steel-tube (CFST) columns are advocated for its better performance contributed by the composite action. However, this composite action cannot be fully developed because of different dilation properties between steel tube and concrete, and very often de-bonding between the constitutive materials will occur initially. To overcome this problem, external confinement in the form of spirals is proposed to improve the interface bonding. In this paper, a total of 38 specimens were fabricated and tested under uni-axial compression. From the results, it can be concluded that the proposed spirals can improve the strength, initial stiffness, ductility and the interface bonding by restraining the lateral expansion of steel tube and core concrete. Lastly, an analytical model evaluating the ultimate strength of spiral-confined CFST columns is proposed and verified. © 2014 Elsevier Ltd. All rights reserved.
Jacobs F.M.J.,University of California at Santa Cruz |
Jacobs F.M.J.,University of Amsterdam |
Greenberg D.,University of California at Santa Cruz |
Greenberg D.,Gladstone |
And 10 more authors.
Nature | Year: 2014
Throughout evolution primate genomes have been modified by waves of retrotransposon insertions. For each wave, the host eventually finds a way to repress retrotransposon transcription and prevent further insertions. In mouse embryonic stem cells, transcriptional silencing of retrotransposons requires KAP1 (also known as TRIM28) and its repressive complex, which can be recruited to target sites by KRAB zinc-finger (KZNF) proteins such as murine-specific ZFP809 which binds to integrated murine leukaemia virus DNA elements and recruits KAP1 to repress them. KZNF genes are one of the fastest growing gene families in primates and this expansion is hypothesized to enable primates to respond to newly emerged retrotransposons. However, the identity of KZNF genes battling retrotransposons currently active in the human genome, such as SINE-VNTR-Alu (SVA) and long interspersed nuclear element 1 (L1), is unknown. Here we show that two primate-specific KZNF genes rapidly evolved to repress these two distinct retrotransposon families shortly after they began to spread in our ancestral genome. ZNF91 underwent a series of structural changes 8-12 million years ago that enabled it to repress SVA elements. ZNF93 evolved earlier to repress the primate L1 lineage until 1/412.5 million years ago when the L1PA3-subfamily of retrotransposons escaped ZNF93's restriction through the removal of the ZNF93-binding site. Our data support a model where KZNF gene expansion limits the activity of newly emerged retrotransposon classes, and this is followed by mutations in these retrotransposons to evade repression, a cycle of events that could explain the rapid expansion of lineage-specific KZNF genes. © 2015 Macmillan Publishers Limited. All rights reserved.
Seebacher F.,University of Sydney |
White C.R.,University of QueenslandQLD |
Franklin C.E.,University of QueenslandQLD
Nature Climate Change | Year: 2015
Understanding how climate change affects natural populations remains one of the greatest challenges for ecology and management of natural resources. Animals can remodel their physiology to compensate for the effects of temperature variation, and this physiological plasticity, or acclimation, can confer resilience to climate change. The current lack of a comprehensive analysis of the capacity for physiological plasticity across taxonomic groups and geographic regions, however, constrains predictions of the impacts of climate change. Here, we assembled the largest database to date to establish the current state of knowledge of physiological plasticity in ectothermic animals. We show that acclimation decreases the sensitivity to temperature and climate change of freshwater and marine animals, but less so in terrestrial animals. Animals from more stable environments have greater capacity for acclimation, and there is a significant trend showing that the capacity for thermal acclimation increases with decreasing latitude. Despite the capacity for acclimation, climate change over the past 20 years has already resulted in increased physiological rates of up to 20%, and we predict further future increases under climate change. The generality of these predictions is limited, however, because much of the world is drastically undersampled in the literature, and these undersampled regions are the areas of greatest need for future research efforts.
Legros G.,CNRS Jean Le Rond d'Alembert Institute |
Torero J.L.,University of QueenslandQLD
Proceedings of the Combustion Institute | Year: 2015
An original phenomenological model for soot production inside a laminar, flat plate boundary layer diffusion flame is presented. The model is compared with experimental measurements conducted in micro-gravity. For the experiments, the fuel, ethylene, is injected through a flat porous burner into an oxidizer stream flowing parallel to the burner surface. The oxidizer is a mixture of 35% oxygen and 65% nitrogen. The fuel and oxidizer velocities are systematically varied. The analysis of the data shows that the streamwise location of the maximum flame height can be considered an unambiguous characteristic length of the flame as opposed to the maximum visible flame length. Analysis of the streamwise location of the maximum flame height enables to establish the transition between "open-tip" and "closed-tip" behavior as well as scaling laws for the soot volume fraction. A scaled soot volume fraction is found to follow a linear relationship with the streamwise coordinate normalized by the burner length. This correlation appears to be valid for the whole range of conditions investigated, knowing that this range does not cover the blow-off regime. © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
Bryant D.,University of QueenslandQLD
Electronic Journal of Combinatorics | Year: 2016
We prove that if H = (V (H); ε(H)) is a hypergraph, γ is an edge colouring of H, and S ⊆ V (H) such that any permutation of S is an automorphism of H, then there exists a permutation π of ε(H) such that |π(E)| = |E| and π(E)\S = E\S for each E ϵ ε(H), and such that the edge colouring γ′ of H given by γ′(E) = γ(π-1(E)) for each E ϵ ε(H) is almost regular on S. The proof is short and elementary. We show that a number of known results, such as Baranyai’s Theorem on almost-regular edge colourings of complete k-uniform hypergraphs, are easy corollaries of this theorem. © 2016, Australian National University. All rights reserved.
Wen J.,University of QueenslandQLD |
Zhong M.,University of QueenslandQLD
Expert Systems with Applications | Year: 2015
In the past decades, activity recognition had aroused great interest for the community of context-awareness computing and human behaviours monitoring. However, most of the previous works focus on supervised methods in which the data labelling is known to be time-consuming and sometimes error-prone. In addition, due to the randomness and erratic nature of human behaviours in realistic environments, supervised models trained with data from certain subject might not be scaled to others. Further more, unsupervised methods, with little knowledge about the activities to be recognised, might result in poor performance and high clustering overhead. To this end, we propose an activity recognition model with labelled and unlabelled data in smart environments. With small amount of labelled data, we discover activity patterns from unlabelled data based on proposed similarity measurement algorithm. Our system does not require large amount of data to be labelled while the proposed similarity measurement method is effective to discover length-varying, disordered and discontinuous activity patterns in smart environments. Therefore, our methods yield comparable performance with much less labelled data when compared with traditional supervised activity recognition, and achieve higher accuracy with lower clustering overhead compared with unsupervised methods. The experiments based on real datasets from the smart environments demonstrate the effectiveness of our method, being able to discover more than 90% of original activities from the unlabelled data, and the comparative experiments show that our methods are capable of providing a better trade-off, regarding the accuracy, overhead and labelling efforts, between the supervised and unsupervised methods. © 2015 Elsevier Ltd All rights reserved.
Zhang M.,University of QueenslandQld |
Yu H.,University of QueenslandQld |
Lyu M.,University of QueenslandQld |
Wang Q.,University of QueenslandQld |
And 2 more authors.
Chemical Communications | Year: 2014
Mixed halide perovskites CH3NH3PbBr3-xClx (x = 0.6-1.2) with different compositions of halogens exhibit drastically changed optical properties. In particular, the thin films prepared with these perovskites demonstrate extraordinary photoluminescence emission intensities and prolonged recombination lifetimes up to 446 ns, which are desirable for light emitting and photovoltaic applications. This journal is © the Partner Organisations 2014.