969 resultados para Ground reaction forces


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Over the past twenty years Australia has witnessed an extraordinary rise of the middle year’s movement. In more recent years, however, there is concern that middle years has fallen from the mainstream education agenda (Australian Research Alliance for Children and Youth, 2011). At a national level, evidence of this fall can be seen in the new national curriculum frameworks where reference to middle years is significantly absent, such as The Shape of the Australian Curriculum Version 2.0, (Australian Curriculum, Assessment and Reporting Authority, 2010). Evidence of the fall at a state level can be seen in Queensland Government’s 2015 commencement of junior secondary, rather than middle years, as outlined in A Flying Start for Queensland children: Why year 7 will be part of high school from 2015 (Queensland Government, 2011a). This announcement came after the Queensland government had undertaken an extensive consultation period exploring the possible uptake of middle years at a systemic level. While some may argue that middle years practices can be seen to be embedded in both the national curriculum and the junior secondary reform – it is the fact that middle years practices and philosophies are implicitly embedded (hidden) rather than being made explicitly and systematically mainstreamed (broadly accepted), that causes us grave concern. As such, we argue that this is clear indication that the middle years are being marginalized from the overarching educational agendas in Australia.

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We consider time-space fractional reaction diffusion equations in two dimensions. This equation is obtained from the standard reaction diffusion equation by replacing the first order time derivative with the Caputo fractional derivative, and the second order space derivatives with the fractional Laplacian. Using the matrix transfer technique proposed by Ilic, Liu, Turner and Anh [Fract. Calc. Appl. Anal., 9:333--349, 2006] and the numerical solution strategy used by Yang, Turner, Liu, and Ilic [SIAM J. Scientific Computing, 33:1159--1180, 2011], the solution of the time-space fractional reaction diffusion equations in two dimensions can be written in terms of a matrix function vector product $f(A)b$ at each time step, where $A$ is an approximate matrix representation of the standard Laplacian. We use the finite volume method over unstructured triangular meshes to generate the matrix $A$, which is therefore non-symmetric. However, the standard Lanczos method for approximating $f(A)b$ requires that $A$ is symmetric. We propose a simple and novel transformation in which the standard Lanczos method is still applicable to find $f(A)b$, despite the loss of symmetry. Numerical results are presented to verify the accuracy and efficiency of our newly proposed numerical solution strategy.

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The global release of 250,000 US Embassy diplomatic cables to selected media sites worldwide through the WikiLeaks website, was arguably the major global media event of 2010. As well as the implications of the content of the cables for international politics and diplomacy, the actions of WikiLeaks and its controversial editor-in-chief, the Australian Julian Assange, bring together a range of arguments about how the media, news and journalism are being transformed in the 21st century. This paper will focus on the reactions of Australian online news media sites to the release of the diplomatic cables by WikiLeaks, including both the online sites of established news outlets such as The Australian, Sydney Morning Herald and The Age, the ABC’s The Drum site, and online-only sites such as Crikey, New Matilda and On Line Opinion. The study focuses on opinion and commentary rather than straight news reportage, and analysis is framed around three issues: WikiLeaks and international diplomacy; implications of WikiLeaks for journalism; and WikiLeaks and democracy, including debates about the organisation and the ethics of its own practice. It also whether a “WikiLeaks Effect” has wider implications for how journalism is conducted in the future, particularly the method of ‘redaction’ of large amounts of computational data.

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This study of photocatalytic oxidation of phenol over titanium dioxide films presents a method for the evaluation of true reaction kinetics. A flat plate reactor was designed for the specific purpose of investigating the influence of various reaction parameters, specifically photocatalytic film thickness, solution flow rate (1–8 l min−1), phenol concentration (20, 40 and 80 ppm), and irradiation intensity (70.6, 57.9, 37.1and 20.4 W m−2), in order to further understand their impact on the reaction kinetics. Special attention was given to the mass transfer phenomena and the influence of film thickness. The kinetics of phenol degradation were investigated with different irradiation levels and initial pollutant concentration. Photocatalytic degradation experiments were performed to evaluate the influence of mass transfer on the reaction and, in addition, the benzoic acid method was applied for the evaluation of mass transfer coefficient. For this study the reactor was modelled as a batch-recycle reactor. A system of equations that accounts for irradiation, mass transfer and reaction rate was developed to describe the photocatalytic process, to fit the experimental data and to obtain kinetic parameters. The rate of phenol photocatalytic oxidation was described by a Langmuir–Hinshelwood type law that included competitive adsorption and degradation of phenol and its by-products. The by-products were modelled through their additive effect on the solution total organic carbon.

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This paper presents a path planning technique for ground vehicles that accounts for the dynamics of the vehicle, the topography of the terrain and the wheel/ground interaction properties such as friction. The first two properties can be estimated using well known sensors and techniques, but the third is not often estimated even though it has a significant effect on the motion of a high-speed vehicle. We introduce a technique which allows the estimation of wheel slip from which frictional parameters can be inferred. We present simulation results which show the importance of modelling topography and ground properties and experimental results which show how ground properties can be estimated along a 350m outdoor traverse.

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This paper presents a three-dimensional numerical analysis of the electromagnetic forces within a high voltage superconducting Fault Current Limiter (FCL) with a saturated core under short-circuit conditions. The effects of electrodynamics forces in power transformer coils under short-circuit conditions have been reported widely. However, the coil arrangement in an FCL with saturated core differs significantly from existing reactive devices. The boundary element method is employed to perform an electromagnetic force analysis on an FCL. The analysis focuses on axial and radial forces of the AC coil. The results are compared to those of a power transformer and important design considerations are highlighted.

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When compared with other arthoplasties, Total Ankle Joint Replacement (TAR) is much less successful. Attempts to remedy this situation by modifying the implant design, for example by making its form more akin to the original ankle anatomy, have largely met with failure. One of the major obstacles is a gap in current knowledge relating to ankle joint force. Specifically this is the lack of reliable data quantifying forces and moments acting on the ankle, in both the healthy and diseased joints. The limited data that does exist is thought to be inaccurate [1] and is based upon simplistic two dimensional discrete and outdated techniques.

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Fractional differential equations are becoming more widely accepted as a powerful tool in modelling anomalous diffusion, which is exhibited by various materials and processes. Recently, researchers have suggested that rather than using constant order fractional operators, some processes are more accurately modelled using fractional orders that vary with time and/or space. In this paper we develop computationally efficient techniques for solving time-variable-order time-space fractional reaction-diffusion equations (tsfrde) using the finite difference scheme. We adopt the Coimbra variable order time fractional operator and variable order fractional Laplacian operator in space where both orders are functions of time. Because the fractional operator is nonlocal, it is challenging to efficiently deal with its long range dependence when using classical numerical techniques to solve such equations. The novelty of our method is that the numerical solution of the time-variable-order tsfrde is written in terms of a matrix function vector product at each time step. This product is approximated efficiently by the Lanczos method, which is a powerful iterative technique for approximating the action of a matrix function by projecting onto a Krylov subspace. Furthermore an adaptive preconditioner is constructed that dramatically reduces the size of the required Krylov subspaces and hence the overall computational cost. Numerical examples, including the variable-order fractional Fisher equation, are presented to demonstrate the accuracy and efficiency of the approach.

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The draft of the first stage of the national curriculum has now been published. Its final form to be presented in December 2010 should be the centrepiece of Labor’s Educational Revolution. All the other aspects – personal computers, new school buildings, rebates for uniforms and even the MySchool report card – are marginal to the prescription of what is to be taught and learnt in schools. The seven authors in this journal’s Point and Counterpoint (Curriculum Perspectives, 30(1) 2010, pp.53-74) raise a number of both large and small issues in education as a whole, and in science education more particularly. Two of them (Groves and McGarry) make brief reference to earlier attempts to achieve national curriculum in Australia. Those writing from New Zealand and USA will be unaware of just how ambitious this project is for Australia - a bold and overdue educational adventure or a foolish political decision destined to failure, as happened in the later 1970s and the 1990s.