3,482 research outputs found

    Design and development of a modular framework to integrate sensors and actuators : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Engineering in Mechatronics at Massey University, Manawatu, New Zealand

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    This thesis details the research and development of a versatile electronic monitoring and control platform, influenced by the Internet of Things (IoT), mass configurability, modularity, expandability and ease of use. The generic framework which has been designed and tested aims to provide a platform to build a wide variety of specialised systems to integrate sensors and actuators. A central processing unit manages modular hardware devices connected by a serial network. Only the required hardware units are chosen to constitute a system for an application. The processing unit uses modular task handlers to manage the system. The web-based user interface provides multi-platform system access using a web browser. The website is dynamically generated from the system configuration. While the framework is generic, for testing its efficacy, it was applied to a seed and fertilizer spreader to monitor and control the application rate. This application requires coordinated control of actuators using inputs from multiple sources, including sensors, machine states, a database, other processing tasks, and the operator. The implementation was successful in achieving reliable control of the seeding rate, based on the tractor ground speed. The practical implementation exhibited a high level of expandability and modularity. The prototype system has also highlighted a few issues which can be addressed in future revisions to improve the versatility and robustness of the framework

    On the large-scale instability in interacting dark energy and dark matter fluids

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    Recently, Valiviita et al. (2008) have reported a large-scale early-time instability in coupled dark energy and dark matter models. We take the same form of energy-momentum exchange and specialise to the case when the interaction rate is proportional to Hubble's parameter and the dark energy density only. Provided the coupling is made small enough for a given equation of state parameter, we show that the instability can be avoided. Expressions are derived for non-adiabatic modes on super-horizon scales in both the radiation and matter dominated regimes. We also examine the growth of dark matter perturbations in the sub-horizon limit. There we find that the coupling has almost no effect upon the growth of structure before dark energy begins to dominate. Once the universe begins to accelerate, the relative dark matter density fluctuations not only cease to grow as in uncoupled models, but actually decay as the universe continues to expand.Comment: Updated to match version published in February edition of Phys.Rev.

    Conflict in the East China Sea: would ANZUS apply?

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    This paper analyses the circumstances under which conflict in the East China Sea could occur and the implications for Australia. Executive summary Tensions between China and Japan have ratcheted up in recent years to the point where their territorial dispute over islands in the East China Sea is seen as among the region’s most dangerous flashpoints. The prospect of Sino-Japanese conflict over these islands is one that cannot be taken lightly by Australia. Economically, three of our four leading trading partners are located in Northeast Asia, while sea lanes vital to Australian trade run through the waters of the East China Sea. Strategically and politically, two US allies are based in this region and America retains a strong forward military presence there. This paper starts from the premise that insufficient attention has been given to the potential ramifications for Australia of conflict in the East China Sea, particularly in terms of whether Australia’s alliance obligations with the United States could embroil Canberra in a conflict. The paper is motivated in part by Defence Minister Johnston’s June 2014 remarks stating that the ANZUS alliance would not commit Australia to a conflict where the US had sent forces to support Japan. While reminiscent of remarks made a decade earlier by then-Foreign Minister Alexander Downer in relation to the prospect of Australian involvement via ANZUS in a Taiwan contingency, Johnston’s assessment has not attracted anywhere near the same level of attention and analysis as those made by Downer in August 2004. The purpose of this paper is to begin to fill this gap in Australia’s public and policy debate by analysing the circumstances under which conflict in the East China Sea could occur and the implications thereof for Australia. The paper answers three questions: 1. What does Australia’s alliance relationship with the US commit Canberra to in the event of conflict in the East China Sea? 2. What are the risks that Australia faces as a result of ANZUS and other associated international commitments? 3. What can be done to better understand and manage these risks

    The Defence White Paper 2013 and Australia's Strategic Environment

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    The depiction of Australia�s strategic environment in the 2013 Defence White Paper has been one of its most favourably received elements. This article examines the White Paper�s treatment of China�s rise, and of the US-China relationship, the newly introduced construct known as the �Indo-Pacific strategic arc�, and the White Paper�s renewed focus on defence engagement with Indonesia, and with Southeast Asia more generally, highlighting some of the challenges of this approach. While acknowledging the favourable reception that much of the analysis contained in the 2013 White Paper has received, the article concludes by observing that it may have over-corrected trying to redress the shortcomings of its 2009 predecessor

    Whose Shared Destiny?

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    THE ‘COMMUNITY OF SHARED DESTINY’ is not a completely new concept in Chinese foreign policy — the Communist Party first used the term in 2007 in relation to cross Strait relations. But it is one that has gained greater prominence over the past year. A key development during this period was Xi Jinping’s October 2013 keynote speech at the ‘Workshop on Diplomatic Work with Neighbouring Countries’ 周边国家外交工作座谈会, during which he elaborated on the ‘shared destiny’ theme (sometimes translated into English as ‘common destiny’): it was then that the term officially entered the Chinese foreign policy lexicon

    Improved Workflow for Unsupervised Multiphase Image Segmentation

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    Quantitative image analysis often depends on accurate classification of pixels through a segmentation process. However, imaging artifacts such as the partial volume effect and sensor noise complicate the classification process. These effects increase the pixel intensity variance of each constituent class, causing intensities from one class to overlap with another. This increased variance makes threshold based segmentation methods insufficient due to ambiguous overlap regions in the pixel intensity distributions. The class ambiguity becomes even more complex for systems with more than two constituents, such as unsaturated moist granular media. In this paper, we propose an image processing workflow that improves segmentation accuracy for multiphase systems. First, the ambiguous transition regions between classes are identified and removed, which allows for global thresholding of single-class regions. Then the transition regions are classified using a distance function, and finally both segmentations are combined into one classified image. This workflow includes three methodologies for identifying transition pixels and we demonstrate on a variety of synthetic images that these approaches are able to accurately separate the ambiguous transition pixels from the single-class regions. For situations with typical amounts of image noise, misclassification errors and area differences calculated between each class of the synthetic images and the resultant segmented images range from 0.69-1.48% and 0.01-0.74%, respectively, showing the segmentation accuracy of this approach. We demonstrate that we are able to accurately segment x-ray microtomography images of moist granular media using these computationally efficient methodologies

    Strategy and its discontents: the place of strategy in national policymaking

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    This paper presents a collection of views about the definition, role, purpose and health of strategic policymaking. Introduction One of the liveliest debates to have taken place on ASPI’s blog, The Strategist, concerned the place of strategy in Canberra’s policymaking community. It seems that there’s little consensus around what strategy’s core business should be, let alone who should practice it and whether indeed enough strategy is being done by DFAT, Defence or other parts of government. The 11 short pieces printed here by eight authors with quite diverse perspectives span a broad range of views about the definition, role, purpose and health of strategic policymaking. There’s no more important debate in public policy than on the place of strategy in meeting complex national challenges. This paper hopefully will encourage a more structured debate about strategy’s place at the heart of national policymaking

    Treating reading difficulties with colour [Editorial]

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    yesAround 3-6% of children in the United Kingdom have substantial difficulties learning to read, a condition often referred to as dyslexia. They are at high risk of educational underachievement. In a 1996 editorial in The BMJ, Margaret Snowling argued that dyslexia is a verbal (not a visual) disorder.1 An accumulation of evidence supports this position and shows that reading difficulties are best dealt with by interventions that target underlying weaknesses in phonological language skills and letter knowledge.2 The 2009 Rose report, which provides guidance for professionals in schools on identifying and teaching young people with dyslexia and reading difficulties, stresses the importance of early, phonological interventions.3 Despite this evidence, dyslexia is often associated with subjective experiences of visual distortions that lead to discomfort during reading (sometimes termed visual stress). It has been argued that these symptoms can be alleviated by using coloured overlays and lenses.4 Symptoms of visual stress are not unique to dyslexia, and proponents do not claim that the use of colour directly addresses the underlying cause of the reading difficulty. However, they argue that the reduction in visual distortion brought about by a change in colour can improve reading accuracy and fluency.

    One-ride human powered vehicle

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    This document discusses the design, analysis, manufacturing and testing of the One-Ride human powered vehicle which was entered into the 2015 ASME West Coast HPVC Competition. The goal of the vehicle is to entice people to switch from gas powered vehicles to the One-Ride for trips of up to 20 miles round trip. The One-Ride design features fully adjustable seating and steering positions and was designed to fit anyone between the heights of 5\u272 and 6\u274 comfortably. The seat is adjusted using metal sliders, manufactured in the SCU machine shop, which fit into brackets attached to the frame. The bike features telescopic steering which is adjusted by the loosening and tightening of collar clamps. To increase the strength and safety of the frame, the welding and heat treatment were contracted to industry professionals. The frame was welded by Chavez Welding and heat treated by Byington Steel Treating. Deformation in the seat frame during heat treatment prevented full adjustability of the seat, however was secured in its middle position for testing. The wheelbase of the bike is 73.33 in and has an overall height of 50.77 in. . Slop in the steering caused instability at low speeds, which prevented the bike from being ridden in the ASME HPVC Competition. Design solutions to both of these problems have been identified. At the completion of senior design, the manufacturing is still ongoing
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