Similarity solutions for flow and heat transfer of non-Newtonian fluid over a stretching surface

Similarity solutions are carried out for flow of power law non-Newtonian fluid film on unsteady stretching surface subjected to constant heat flux. Free convection heat transfer induces thermal boundary layer within a semi-infinite layer of Boussinesq fluid. The nonlinear coupled partial differential equations (PDE) governing the flow and the boundary conditions are converted to a system of ordinary differential equations (ODE) using two-parameter groups. This technique reduces the number of independent variables by two, and finally the obtained ordinary differential equations are solved numerically for the temperature and velocity using the shooting method. The thermal and velocity boundary layers are studied by the means of Prandtl number and non-Newtonian power index plotted in curves.

A biomechanical analysis of growing rods used in the management of early onset scoliosis

INTRODUCTION Managing spinal deformities in young children is challenging, particularly early onset scoliosis (EOS). Surgical intervention is often required if EOS has been unresponsive to conservative treatment particularly with rapidly progressive curves. An emerging treatment option for EOS is fusionless scoliosis surgery. Similar to bracing, this surgical option potentially harnesses growth, motion and function of the spine along with correcting spinal deformity. Dual growing rods are one such fusionless treatment, which aims to modulate growth of the vertebrae. The aim of this study was to ascertain the extent to which semiconstrained growing rods (Medtronic, Sofamor, Danek, Memphis, TN) with a telescopic sleeve component, reduce rotational constraint on the spine compared with standard "constrained / rigid" rods and hence potentially provide a more physiological mechanical environment for the growing spine. METHODS Six 40-60kg English Large White porcine spines served as a model for the paediatric human spine. Each spine was dissected into a 7 level thoracolumbar multi-segment unit (MSU), removing all non-ligamentous soft tissues and leaving 3cm of ribs either side. Pure nondestructive axial rotation moments of ±4Nm at a constant rotation rate of 8deg.s-1 were applied to the mounted MSU spines using a biaxial Instron testing machine. Displacement of each vertebral level was captured using a 3D motion tracking system (Optotrak 3020, Northern Digital Inc, Waterloo, ON). Each spine was tested in an un-instrumented state first and then with appropriately sized semi-constrained growing rods and rigid rods in alternating sequence. The rods were secured by multi-axial pedicle screws (Medtronic CD Horizon) at levels 2 and 6 of the construct. The range of motion (ROM), neutral zone (NZ) size and stiffness (Nm.deg-1) were calculated from the Instron load-displacement data and intervertebral ROM was calculated through a MATLAB algorithm from Optotrak data. RESULTS Irrespective of the order of testing, rigid rods significantly reduced the total ROM compared with semi-constrained rods (p<0.05) with in a significantly stiffer spine for both left and right axial rotation (p<0.05). Analysing the intervertebral motion within the instrumented levels 2-6, rigid rods showed reduced ROM compared with semi-constrained growing rods and compared with un-instrumented motion segments. CONCLUSION Semi-constrained growing rods maintain similar stiffness in axial rotation to un-instrumented spines, while dual rigid rods significantly reduce axial rotation. Clinically the effect of semi-constrained growing rods as observed in this study is that they would be expected to allow growth via the telescopic rod components while maintaining the axial flexibility of the spine, which may reduce occurrence of the crankshaft phenomenon.

In conversation with the Honourable Ian Callinan AC

When, in 1977, the Australian electorate provided a double majority to effect a change of section 72 of the Commonwealth Constitution requiring judges of the High Court of Australia to retire at the age of 70 years old, I doubt we understood the continuing capacity of these esteemed members of the judiciary. For the opportunity to sit and talk with Ian Callinan AC who, in compliance with that amendment, retired from the High Court in September 2007, I needed to wait until he returned from The Hague where he was sitting as a Judge ad hoc on the International Court of Justice. Although a native of Casino, New South Wales, Mr Callinan is regarded as a Queenslander. Indeed, he grew up in Brisbane, finished high school at Brisbane Grammar and graduated in law at The University of Queensland. Appointed in 1978 as a Queen’s Counsel, Mr Callinan enjoyed this period of his legal career and we discussed an aspect of the Christopher Skase case, which reinforced my belief that Mr Callinan is an incredibly skilful advocate. On 14 September 1998, ABC Four Corners broadcasted the views of some prominent Australians on the appointment of Mr Callinan to the High Court. In assessing the type of person Mr Callinan is, Tony Morris QC said: “Ian Callinan isn't a coward”, while former Commonwealth Attorney-General, Michael Lavarch, said: “He was regarded as an absolutely outstanding criminal lawyer within the Queensland legal profession, I mean really a top-notch advocate”. I was not interested in raising any of the controversial issues that Mr Callinan has encountered as an advocate in high profile matters. I wanted to know how he felt about his time on the High Court, what his thoughts are on the operation of the High Court, the IP cases he decided, the real life issues that he feels impact on counsel who are appearing before the High Court and the people he regarded as role models. During our conversation, Mr Callinan laughed often and when he did his eyes lit up, revealing his passion for life. He is an incredibly genuine Australian who loved his time as a barrister, enjoyed his role on the High Court, enjoys his current job as mediator, loves writing novels, has a great desire for continual improvement in the quality of legal education and legal advocacy and sees a need for change in IP law. When I asked: “So, what might the future hold for you?”, he laughed and said: “Well, at my age I don’t have a long horizon time”. I said: “Just enjoy the journey?”, to which Mr Callinan responded: “Exactly”.

The Pareto regret frontier

Performance guarantees for online learning algorithms typically take the form of regret bounds, which express that the cumulative loss overhead compared to the best expert in hindsight is small. In the common case of large but structured expert sets we typically wish to keep the regret especially small compared to simple experts, at the cost of modest additional overhead compared to more complex others. We study which such regret trade-offs can be achieved, and how. We analyse regret w.r.t. each individual expert as a multi-objective criterion in the simple but fundamental case of absolute loss. We characterise the achievable and Pareto optimal trade-offs, and the corresponding optimal strategies for each sample size both exactly for each finite horizon and asymptotically.

Beyond point forecasting : evaluation of alternative prediction intervals for tourist arrivals

This paper evaluates the performances of prediction intervals generated from alternative time series models, in the context of tourism forecasting. The forecasting methods considered include the autoregressive (AR) model, the AR model using the bias-corrected bootstrap, seasonal ARIMA models, innovations state space models for exponential smoothing, and Harvey’s structural time series models. We use thirteen monthly time series for the number of tourist arrivals to Hong Kong and Australia. The mean coverage rates and widths of the alternative prediction intervals are evaluated in an empirical setting. It is found that all models produce satisfactory prediction intervals, except for the autoregressive model. In particular, those based on the biascorrected bootstrap perform best in general, providing tight intervals with accurate coverage rates, especially when the forecast horizon is long.

Simultaneous localization and planning on multiple map hypotheses

This paper presents a novel method to rank map hypotheses by the quality of localization they afford. The highest ranked hypothesis at any moment becomes the active representation that is used to guide the robot to its goal location. A single static representation is insufficient for navigation in dynamic environments where paths can be blocked periodically, a common scenario which poses significant challenges for typical planners. In our approach we simultaneously rank multiple map hypotheses by the influence that localization in each of them has on locally accurate odometry. This is done online for the current locally accurate window by formulating a factor graph of odometry relaxed by localization constraints. Comparison of the resulting perturbed odometry of each hypothesis with the original odometry yields a score that can be used to rank map hypotheses by their utility. We deploy the proposed approach on a real robot navigating a structurally noisy office environment. The configuration of the environment is physically altered outside the robots sensory horizon during navigation tasks to demonstrate the proposed approach of hypothesis selection.

Powering a curriculum for all : a critical ethnographic study of inclusive education

This project makes a contribution to knowledge about the successful leadership practices that enhance education for young people with a disability in a Queensland Secondary School. The project used a critical ethnographic approach with a variety of data collection methods and analysis. For example, the use of work diaries, semi-structured interviews, document analysis and observation. These leadership practices were found to be relevant to the development of inclusive schools for all learners.The most powerful leadership practices found were those used by the leader to challenge, interupt and replace exsisting discourse and processes that led to exclusion of students with a disability.

Just dawn

Commissioned for the It’s Timely exhibition at the Blacktown Arts Centre, Just Dawn is a response to two speeches that former Australian Prime Minister Gough Whitlam delivered in Blacktown in 1972 and 1974. Throughout the video, a series of white words and phrases fade in and out as a virtual camera flies towards an abstract horizon line. The narrative thread of the text is directed towards an unnamed Whitlam through the repeated appearance of the words ‘you said’. As the video progresses, the colours of the animated background slowly brighten to resemble an emerging dawn, and the sound, text and camera movements build in frequency and intensity. As they do so, the once optimistic outlook becomes increasingly unsteady. In these ways, Just Dawn is equal parts homage and lament for the ideological acuity and ambition of Whitlam’s agenda. It explores how Whitlam’s words can become markers for the complexities of both his own specific transformative policies, and the character of the socially progressive movement more broadly.

The value of tail risk hedging in defined contribution plans: What does history tell us

Hedging against tail events in equity markets has been forcefully advocated in the aftermath of recent global financial crisis. Whether this is beneficial to long horizon investors like employees enrolled in defined contribution (DC) plans, however, has been subject to criticism. We conduct historical simulation since 1928 to examine the effectiveness of active and passive tail risk hedging using out of money put options for hypothetical equity portfolios of DC plan participants with 20 years to retirement. Our findings show that the cost of tail hedging exceeds the benefits for a majority of the plan participants during the sample period. However, for a significant number of simulations, hedging result in superior outcomes relative to an unhedged position. Active tail hedging is more effective when employees confront several panic-driven periods characterized by short and sharp market swings in the equity markets over the investment horizon. Passive hedging, on the other hand, proves beneficial when they encounter an extremely rare event like the Great Depression as equity markets go into deep and prolonged decline.

Decriminalization of Health and Safety at Work in Australia

ABOUT THE BOOK As the title Safety or Profit? suggests, health and safety at work needs to be understood in the context of the wider political economy. This book brings together contributions informed by this view from internationally recognized scholars. It reviews the governance of health and safety at work, with special reference to Australia, Canada, Sweden, and the United Kingdom. Three main aspects are discussed. The restructuring of the labor market: this is considered with respect to precarious work and to gender issues and their implications for the health and safety of workers. The neoliberal agenda: this is examined with respect to the diminished power of organized labor, decriminalization, and new governance theory, including an examination of how well the health-and-safety-at-work regimes put in place in many industrial societies about forty years ago have fared and how distinctive the recent emphasis on self-regulation in several countries really is. The role of evidence: there is a dearth of evidence-based policy. The book examines how policy on health and safety at work is formulated at both company and state levels. Cases considered include the scant regard paid to evidence by an official inquiry into future strategy in Canada; the lack of evidence-based policy and the reluctance to observe the precautionary principle with respect to work-related cancer in the United Kingdom; and the failure to learn from past mistakes in the Deepwater Horizon disaster in the Gulf of Mexico. Intended Audience: Researchers; policymakers, trade union representatives, and officials interested in OHS; postgraduate students of OHS; OHS professionals; regulatory and socio-legal scholars.

Design of a nonlinear excitation controller using inverse filtering for transient stability enhancement

This paper proposes a nonlinear excitation controller to improve transient stability, oscillation damping and voltage regulation of the power system. The energy function of the predicted system states is used to obtain the desired flux for the next time step, which in turn is used to obtain a supplementary control input using an inverse filtering method. The inverse filtering technique enables the system to provide an additional input for the excitation system, which forces the system to track the desired flux. Synchronous generator flux saturation model is used in this paper. A single machine infinite bus (SMIB) test system is used to demonstrate the efficacy of the proposed control method using time-domain simulations. The robustness of the controller is assessed under different operating conditions.

Mineralogy and Magnetic Properties of Basaltic Substrate Soils: Kaho'olawe and Big Island, Hawaii

Magnetic behavior of soils can seriously hamper the performance of geophysical sensors. Currently, we have little understanding of the types of minerals responsible for the magnetic behavior, as well as their distribution in space and evolution through time. This study investigated the magnetic characteristics and mineralogy of Fe-rich soils developed on basaltic substrate in Hawaii. We measured the spatial distribution of magnetic susceptibility (χlf) and frequency dependence (χfd%) across three test areas in a well-developed eroded soil on Kaho'olawe and in two young soils on the Big Island of Hawaii. X-ray diffraction spectroscopy, x-ray fluorescence spectroscopy (XFCF), chemical dissolution, thermal analysis, and temperature-dependent magnetic studies were used to characterize soil development and mineralogy for samples from soil pits on Kaho'olawe, surface samples from all three test areas, and unweathered basalt from the Big Island of Hawaii. The measurements show a general increase in magnetic properties with increasing soil development. The XRF Fe data ranged from 13% for fresh basalt and young soils on the Big Island to 58% for material from the B horizon of Kaho'olawe soils. Dithionite-extractable and oxalate-extractable Fe percentages increase with soil development and correlate with χlf-and χfd%, respectively. Results from the temperature-dependent susceptibility measurements show that the high soil magnetic properties observed in geophysical surveys in Kaho'olawe are entirely due to neoformed minerals. The results of our studies have implications for the existing soil survey of Kaho'olawe and help identify methods to characterize magnetic minerals in tropical soils.

Some Reflections on the Emergence of Multimodal Assemblages of Meaning

In this commentary I reflect upon the conceptualisation of human meaning-making, utilised in the two target articles, that relies heavily on speech as the main mode of semiosis and considers time only in its chronological form. Instead I argue that human existence is embodied and lived through multiple modalities, and involves not only sequential experience of time, but also experience of emergence. In order to move towards a conception of meaning-making that takes this into account, I introduce the social-semiotic theory of multimodality (Kress 2010) and discuss notions of ‘real duration’ (Bergson 1907/1998) and ‘lived time’ (Martin-Vallas 2009). I argue that dialogical (idiographic) researchers need to develop analytic and methodological tools that allow exploring the emergence of multimodal assemblages of meaning in addition to trying to avoid the monologisation of complex dynamic dialogical phenomena.

Making robust decisions for conservation with restricted money and knowledge

1. In conservation decision-making, we operate within the confines of limited funding. Furthermore, we often assume particular relationships between management impact and our investment in management. The structure of these relationships, however, is rarely known with certainty - there is model uncertainty. We investigate how these two fundamentally limiting factors in conservation management, money and knowledge, impact optimal decision-making. 2. We use information-gap decision theory to find strategies for maximizing the number of extant subpopulations of a threatened species that are most immune to failure due to model uncertainty. We thus find a robust framework for exploring optimal decision-making. 3. The performance of every strategy decreases as model uncertainty increases. 4. The strategy most robust to model uncertainty depends not only on what performance is perceived to be acceptable but also on available funding and the time horizon over which extinction is considered. 5. Synthesis and applications. We investigate the impact of model uncertainty on robust decision-making in conservation and how this is affected by available conservation funding. We show that subpopulation triage can be a natural consequence of robust decision-making. We highlight the need for managers to consider triage not as merely giving up, but as a tool for ensuring species persistence in light of the urgency of most conservation requirements, uncertainty and the poor state of conservation funding. We illustrate this theory by a specific application to allocation of funding to reduce poaching impact on the Sumatran tiger Panthera tigris sumatrae in Kerinci Seblat National Park. © 2008 The Authors.

Contracted site: Artist on paper, drawing

Traditionally the notion of drawing in-situ has suggested the physical presence of the artist in the environment under scrutiny. The assumption here of enhanced connectivity, however, is hasty in light of the idea that situation implies a relative spatial value determined by the interplay of subject and location, where the possibility of not being “in-situ” is problematic. The fact that traditional drawing in-situ, such as the rendering of landscape, requires a framing of the world “out there” suggests a distance between the perceived object of representation and the drawing surface. Rather than suggesting that some drawing is situated and other sorts of drawing are not, however, I argue that situation or site is variously extended and intensified depending on the nature of mediation between surface and environment. The suggestion here is that site is not so much a precondition as a performative function, developed in the act of drawing and always implicating the drawing surface. In my discussion I focus on specific works by Toba Khedoori and Cameron Robbins. As well, in using my own recent drawing practice as a case study, I argue that the geography of site is delimited neither by horizon nor the boundaries of the paper. Rather, I propose that site and drawing surface coincide in variously intensive and extensive ways.