342 resultados para fault current limiter
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BACKGROUND Engineering is a problem-based practically oriented discipline, whose practitioners aim to find effective solutions to engineering challenges, technically and economically. Engineering educators operate within a mandate to ensure that graduate engineers understand the practicalities and realities of good engineering practice. While this is a vital goal for the discipline, emerging influences are challenging the focus on ‘hard practicalities’ and requiring recognition of the cultural and social aspects of engineering. Expecting graduate engineers to possess communication skills essential for negotiating satisfactory outcomes in contexts of complex social beliefs about the impact of their work can be an unsettling and challenging prospect for engineering educators. This project identifies and addresses Indigenous engineering practices and principles, and their relevance to future engineering practices. PURPOSE This Office of Learning and Teaching (OLT) project proposes that what is known/discoverable about indigenous engineering knowledge and practices must be integrated into engineering curricula. This is an important aspect of ensuring that engineering as a profession responds competently to increasing demands for socially and environmentally responsible activity across all aspects of engineering activity. DESIGN/METHOD The project addresses i) means for appropriate inclusion of Indigenous students into usual teaching activities ii) assuring engineering educators have access to knowledge of Indigenous practices and skills relevant to particular engineering courses and topics iii) means for preparing all students to negotiate their way through issues of indigenous relationships with the land where engineering projects are planned. The project is undertaking wide-ranging research to collate knowledge about indigenous engineering principles and practices and develop relevant resource materials. RESULTS It is common to hear that such social issues as ‘Indigenous concerns’ are only of concern to environmental engineers. We challenge that perspective, and make the case that Indigenous knowledge is an important issue for all engineering educators in relation to effective integration of indigenous students and preparation of all engineering graduates to engage with indigenous communities. At the time of first contact, a rich and varied, technically literate, Indigenous social framework possessed knowledge of the environment that is not yet fully acknowledged in Australian society. A core outcome of the work will be development of resources relating to Indigenous engineering practices for inclusion in engineering core curricula. CONCLUSIONS A large body of technical knowledge was needed to survive and sustain human society in the complex environment that was Australia before 1788. This project is developing resource materials, and supporting documentation, about that knowledge to enable engineering educators to more easily integrate it into current curricula. The project also aims to demonstrate the importance for graduating engineers to appreciate the existence of diverse perspectives on engineering tasks and learn how to value - and employ - multiple paths to possible solutions.
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There is a growing awareness of the high levels of psychological distress being experienced by law students and the practising profession in Australia. In this context, a Threshold Learning Outcome (TLO) on self-management has been included in the six TLOs recently articulated as minimum learning outcomes for all Australian graduates of the Bachelor of Laws degree (LLB). The TLOs were developed during 2010 as part of the Australian Learning and Teaching Council’s (ALTC’s) project funded by the Australian Government to articulate ‘Learning and Teaching Academic Standards’. The TLOs are the result of a comprehensive national consultation process led by the ALTC’s Discipline Scholars: Law, Professors Sally Kift and Mark Israel.1 The TLOs have been endorsed by the Council of Australian Law Deans (CALD) and have received broad support from members of the judiciary and practising profession, representative bodies of the legal profession, law students and recent graduates, Legal Services Commissioners and the Law Admissions Consultative Committee. At the time of writing, TLOs for the Juris Doctor (JD) are also being developed, utilising the TLOs articulated for the LLB as their starting point but restating the JD requirements as the higher order outcomes expected of graduates of a ‘Masters Degree (Extended)’, this being the award level designation for the JD now set out in the new Australian Qualifications Framework.2 As Australian law schools begin embedding the learning, teaching and assessment of the TLOs in their curricula, and seek to assure graduates’ achievement of them, guidance on the implementation of the self-management TLO is salient and timely.
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A modularized battery system with Double Star Chopper Cell (DSCC) based modular multilevel converter is proposed for a battery operated electric vehicle (EV). A design concept for the modularized battery micro-packs for DSCC is described. Multidimensional pulse width modulation (MD-PWM) with integrated inter-module SoC balancing and fault tolerant control is proposed and explained. The DSCC can be operated either as an inverter to drive the EV motor or as a synchronous rectifier connected to external three phase power supply equipment for charging the battery micro-packs. The methods of operation as inverter and synchronous rectifier with integrated inter-module SoC balancing and fault tolerant control are discussed. The proposed system operation as inverter and synchronous rectifier are verified through simulations and the results are presented.
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A switching control strategy is proposed for single inductor current-fed push-pull converter with a secondary side active voltage doubler rectifier or a voltage rectifier used in photovoltaic (PV) grid interfacing. The proposed switching control strategy helps to turn-on and turn-off the primary side power switches with zero-voltage and zero-current switching. The operation of the push-pull converter is analyzed for two modes of operation. The feasibility of the proposed switching control strategy is validated using simulation and experimental results.
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A high-frequency-link micro inverter is proposed with a front-end dual inductor push-pull converter and a grid-connected half-wave cycloconverter. Pulse width modulation is used to control the front-end converter and phase shift modulation is used at the back-end converter to obtain grid synchronized output current. A series resonant circuit and high-frequency transformer are used to interface the front-end and the back-end converters. The operation of the proposed micro-inverter in grid-connected mode is validated using MATLAB/Simpower simulation. Experimental results are provided to further validate the operation.
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BACKGROUND Traumatic brain injury (TBI) is associated with mo st trauma-related deaths. Secondary brain injury is the leading cause of in-hospital deaths after traumatic brain injury. By early prevention and slowing of the initial pathophysiological mechanism of secondary brain injury, pre- hospital service can signifi cantly reduce case-fata lity rates of TBI. In China, the incidence of TBI is increasing and the proportion of severe TBI is much higher than that in other countries. The objective of this paper is to review the pre-hospital management of TBI in China. DATA SOURCES A literature search was conducted in January 2014 using the China National Knowledge Infrastructure (CNKI). Articles on the assessment and treatment of TBI in pre-hospital settings practiced by Chinese doctors were identified. The information on the assessment and treatment of hypoxemia, hypotension, and brain hern iation was extracted from the identifi ed articles. RESULTS Of the 471 articles identified, 65 met the selecti on criteria. The existing literature indicated that current practices of pre-hospital TBI management in China were sub-optimal and varied considerably across different regions. CONCLUSION Since pre-hospital care is the weakest part of Chinese emergency care, appropriate training programs on pre-hospital TBI management are urgently needed in China.
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In order to support innovation and productivity to ensure ongoing national economic development and growth, the current policy environment of the Australian Federal Government seeks to enhance the quality of education, encourage widened access to education opportunities, and stimulate integration between vocational education and training and higher education. There is increasing evidence of the multiple avenues of transition within and between vocational education and training and higher education. ePortfolios offer the potential to be a meaningful medium for convergence and integration of education and training.
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Wind energy, being the fastest growing renewable energy source in the present world, requires a large number of wind turbines to transform wind energy into electricity. One factor driving the cost of this energy is the reliable operation of these turbines. Therefore, it is a growing requirement within the wind farm community, to monitor the operation of the wind turbines on a continuous basis so that a possible fault can be detected ahead of time. As the wind turbine operates in an environment of constantly changing wind speed, it is a challenging task to design a fault detection technique which can accommodate the stochastic operational behavior of the turbines. Addressing this issue, this paper proposes a novel fault detection criterion which is robust against operational uncertainty, as well as having the ability to quantify severity level specifically of the drivetrain abnormality within an operating wind turbine. A benchmark model of wind turbine has been utilized to simulate drivetrain fault condition and effectiveness of the proposed technique has been tested accordingly. From the simulation result it can be concluded that the proposed criterion exhibits consistent performance for drivetrain faults for varying wind speed and has linear relationship with the fault severity level.
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In this paper, we propose a highly reliable fault diagnosis scheme for incipient low-speed rolling element bearing failures. The scheme consists of fault feature calculation, discriminative fault feature analysis, and fault classification. The proposed approach first computes wavelet-based fault features, including the respective relative wavelet packet node energy and entropy, by applying a wavelet packet transform to an incoming acoustic emission signal. The most discriminative fault features are then filtered from the originally produced feature vector by using discriminative fault feature analysis based on a binary bat algorithm (BBA). Finally, the proposed approach employs one-against-all multiclass support vector machines to identify multiple low-speed rolling element bearing defects. This study compares the proposed BBA-based dimensionality reduction scheme with four other dimensionality reduction methodologies in terms of classification performance. Experimental results show that the proposed methodology is superior to other dimensionality reduction approaches, yielding an average classification accuracy of 94.9%, 95.8%, and 98.4% under bearing rotational speeds at 20 revolutions-per-minute (RPM), 80 RPM, and 140 RPM, respectively.
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Book description: "Over 50,000 new cases of head and neck cancer are diagnosed each year in the United States. The majority of these are squamous cell carcinoma (HNSCC), associated with human papillomavirus infection and carcinogenic behaviors such as tobacco use and alcohol consumption. Although these are more common, there are several other causes that this book addresses. This book examines the epidemiology of head and neck cancer. It discusses the management of head neck cancer as well as treatment outcomes."--publisher website
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This case study investigated EFL assessment practices at one public and one private university to explore the support of assessment for English language learning (ELL) within the Vietnamese sociocultural context. Findings demonstrated the potential of assessment to engage students in learning; enhance their understanding of the learning objectives; and facilitate their learning reflection. Findings also identified strong influences of contextual factors such as teachers' language assessment literacy, high-stakes testing and institutional administrative policies on the practices of assessment for ELL. This study contributes to research on Assessment for Learning and EFL education at tertiary level in Vietnam and other similar sociocultural contexts.
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This thesis provides a review of 199 papers published on Green IT/IS between 2007−2014, in order to present taxonomy of segments in Green IT/IS publications, where the segments are later used for multiple analyses to facilitate future research and to provide a retrospective analysis of existing knowledge and gaps thereof. This research also attempts to make a unique contribution to our understanding of Green IT/IS, by consolidating papers it observes current patterns of literature through approach analysis and segmentation, as well as allocating studies to the technology, process, or outcome (TPO) stage. Highlighting the necessity of a consolidated approach, these classification systems have been combined into a TPO matrix so that the studies could be arranged according to which stage of the Green IT/IS cycle they were focused on. We believe that these analyses will provide a solid platform from which future Green IT/IS research can be launched.
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BACKGROUND Ongoing shortages of blood products may be addressed through additional donations. However, donation frequency rates are typically lower than medically possible. This preliminary study aims to determine voluntary nonremunerated whole blood (WB) and plasmapheresis donors' willingness, and subsequent facilitators and barriers, to make additional donations of a different type. STUDY DESIGN AND METHODS Forty individual telephone interviews were conducted posing two additional donation pattern scenarios: first, making a single and, second, making multiple plasmapheresis donations between WB donations. Stratified purposive sampling was conducted for four samples varying in donation experience: no-plasma, new-to-both-WB-and-plasma, new-to-plasma, and plasma donors. Interviews were analyzed yielding excellent (κ values > 0.81) inter-rater reliability. RESULTS Facilitators were more endorsed than barriers for a single but not multiple plasmapheresis donation. More new-to-both donors (n = 5) were willing to make multiple plasma donations between WB donations than others (n = 1 each) and identified fewer barriers (n = 3) than those more experienced in donation (n = 8 no plasma, n = 10 new to both, n = 11 plasma). Donors in the plasma sample were concerned about the subsequent reduced time between plasma donations by adding WB donations (n = 3). The no-plasma and new-to-plasma donors were concerned about the time commitment required (n = 3). CONCLUSION Current donors are willing to add different product donations but donation history influences their willingness to change. Early introduction of multiple donation types, variation in inventory levels, and addressing barriers will provide blood collection agencies with a novel and cost-effective inventory management strategy.