777 resultados para Electric current converters Study and teaching.
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Learning and teaching approaches to engineering are generally perceived to be difficult and academically challenging. Such challenges are reflected in high levels of student attrition and failure. In addressing this issue, a unique approach to engineering education has been developed by the paper authors. This approach, which is suitable for undergraduate and postgraduate levels, brings together pedagogic and engineering epistemologies in an empirically grounded framework. It is underpinned by three distinctive concepts: Relationships, Variety & Synergy. Based upon research, the R + V + S approach to Engineering Education provides a learning and teaching strategy, which in enhancing the student experience, increases retention and positively impacts student success [S2]. Based on the study findings, this paper shows how, by designing engineering education around the concepts of Relationships, Variety and Synergy, the student learning experience becomes one that is academically challenging yet beneficial to both students and engineering educators. The challenge is to widen and test the approach in other areas of engineering education, before going on to investigate the value of the approach in other disciplines.
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Introduction: The research and teaching of French linguistics in UK higher education (HE) institutions have a venerable history; a number of universities have traditionally offered philology or history of the language courses, which complement literary study. A deeper understanding of the way that the phonology, syntax and semantics of the French language have evolved gives students linguistic insights that dovetail with their study of the Roman de Renart, Rabelais, Racine or the nouveau roman. There was, in the past, some coverage of contemporary French phonetics but little on sociolinguistic issues. More recently, new areas of research and teaching have been developed, with a particular focus on contemporary spoken French and on sociolinguistics. Well supported by funding councils, UK researchers are also making an important contribution in other areas: phonetics and phonology, syntax, pragmatics and second-language acquisition. A fair proportion of French linguistics research occurs outside French sections in psychology or applied linguistics departments. In addition, the UK plays a particular role in bringing together European and North American intellectual traditions and methodologies and in promoting the internationalisation of French linguistics research through the strength of its subject associations, and that of the Journal of French Language Studies. The following sections treat each of these areas in turn. History of the French Language There is a long and distinguished tradition in Britain of teaching and research on the history of the French language, particularly, but by no means exclusively, at the universities of Cambridge, Manchester and Oxford.
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This work looks at the effect on mid-gap interface state defect density estimates for In0.53Ga0.47As semiconductor capacitors when different AC voltage amplitudes are selected for a fixed voltage bias step size (100 mV) during room temperature only electrical characterization. Results are presented for Au/Ni/Al2O3/In0.53Ga0.47As/InP metal–oxide–semiconductor capacitors with (1) n-type and p-type semiconductors, (2) different Al2O3 thicknesses, (3) different In0.53Ga0.47As surface passivation concentrations of ammonium sulphide, and (4) different transfer times to the atomic layer deposition chamber after passivation treatment on the semiconductor surface—thereby demonstrating a cross-section of device characteristics. The authors set out to determine the importance of the AC voltage amplitude selection on the interface state defect density extractions and whether this selection has a combined effect with the oxide capacitance. These capacitors are prototypical of the type of gate oxide material stacks that could form equivalent metal–oxide–semiconductor field-effect transistors beyond the 32 nm technology node. The authors do not attempt to achieve the best scaled equivalent oxide thickness in this work, as our focus is on accurately extracting device properties that will allow the investigation and reduction of interface state defect densities at the high-k/III–V semiconductor interface. The operating voltage for future devices will be reduced, potentially leading to an associated reduction in the AC voltage amplitude, which will force a decrease in the signal-to-noise ratio of electrical responses and could therefore result in less accurate impedance measurements. A concern thus arises regarding the accuracy of the electrical property extractions using such impedance measurements for future devices, particularly in relation to the mid-gap interface state defect density estimated from the conductance method and from the combined high–low frequency capacitance–voltage method. The authors apply a fixed voltage step of 100 mV for all voltage sweep measurements at each AC frequency. Each of these measurements is repeated 15 times for the equidistant AC voltage amplitudes between 10 mV and 150 mV. This provides the desired AC voltage amplitude to step size ratios from 1:10 to 3:2. Our results indicate that, although the selection of the oxide capacitance is important both to the success and accuracy of the extraction method, the mid-gap interface state defect density extractions are not overly sensitive to the AC voltage amplitude employed regardless of what oxide capacitance is used in the extractions, particularly in the range from 50% below the voltage sweep step size to 50% above it. Therefore, the use of larger AC voltage amplitudes in this range to achieve a better signal-to-noise ratio during impedance measurements for future low operating voltage devices will not distort the extracted interface state defect density.
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Research from an international perspective in relation to the preparation of pre service teachers in physical education and special educational needs indicates that initial teacher training providers are inconsistent in the amount of time spent addressing the issue and the nature of curricular content (Vickerman, 2007). In Ireland, research of Meegan and MacPhail (2005) and Crawford (2011) indicates that physical education teachers do not feel adequately prepared to accommodate students with Special Educational Needs (SEN) in physical education classes. This study examined initial teacher training provision in Ireland in the training of pre service physical education teachers in SEN. The methodology used was qualitative and included questionnaires and interviews (n=4). Findings indicated that time allocation (semester long modules), working with children with disabilities in mainstream settings (school or leisure centre based), lack of collaboration with other PETE providers (n=4) and a need for continued professional development were themes in need of address. Using a combined approach where the recently designed European Inclusive Physical Education Training (Kudlácěk, Jesina, & Flanagan, 2010) model is infused through the undergraduate degree programme is proposed. Further, the accommodation of hands on experience for undergraduates in mainstream settings and the establishment of inter institutional communities of practice, with a national disability research initiative, is essential to ensure quality adapted physical activity training can be accommodated throughout Ireland.
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Interaction of ocean waves, currents and sea bed roughness is a complicated phenomena in fluid dynamic. This paper will describe the governing equations of motions of this phenomena in viscous and nonviscous conditions as well as study and analysis the experimental results of sets of physical models on waves, currents and artificial roughness, and consists of three parts: First, by establishing some typical patterns of roughness, the effects of sea bed roughness on a uniform current has been studied, as well as the manning coefficient of each type is reviewed to find the critical situation due to different arrangement. Second, the effect of roughness on wave parameters changes, such as wave height, wave length, and wave dispersion equations have been studied, third, superimposing, the waves + current + roughness patterns established in a flume, equipped with waves + currents generator, in this stage different analysis has been done to find the governing dimensionless numbers, and present the numbers to define the contortions and formulations of this phenomena. First step of the model is verified by the so called Chinese method, and the Second step by the Kamphius (1975), and third step by the van Rijn (1990) , and Brevik and Ass ( 1980), and in all cases reasonable agreements have been obtained. Finally new dimensionless parameters presented for this complicated phenomena.
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In recent years the photovoltaic generation has had greater insertion in the energy mix of the most developed countries, growing at annual rates of over 30%. The pressure for the reduction of pollutant emissions, diversification of the energy mix and the drop in prices are the main factors driving this growth. Grid tied systems plays an important role in alleviating the energy crisis and diversification of energy sources. Among the grid tied systems, building integrated photovoltaic systems suffers from partial shading of the photovoltaic modules and consequently the energy yield is reduced. In such cases, classical forms of modules connection do not produce good results and new techniques have been developed to increase the amount of energy produced by a set of modules. In the parallel connection technique of photovoltaic modules, a high voltage gain DC-DC converter is required, which is relatively complex to build with high efficiency. The current-fed isolated converters explored in this work have some desirable characteristics for this type of application, such as: low input current ripple and input voltage ripple, high voltage gain, galvanic isolation, feature high power capacity and it achieve soft switching in a wide operating range. This study presents contributions to the study of a high gain and high efficiency DC-DC converter for use in a parallel system of photovoltaic generation, being possible the use in a microinverter or with central inverter. The main contributions of this work are: analysis of the active clamping circuit operation proposing that the clamp capacitor connection must be done on the negative node of the power supply to reduce the input current ripple and thus reduce the filter requirements; use of a voltage doubler in the output rectifier to reduce the number of components and to extend the gain of the converter; detailed study of the converter components in order to raise the efficiency; obtaining the AC equivalent model and control system design. As a result, a DC-DC converter with high gain, high efficiency and without electrolytic capacitors in the power stage was developed. In the final part of this work the DC-DC converter operation connected to an inverter is presented. Besides, the DC bus controller is designed and are implemented two maximum power point tracking algorithms. Experimental results of full system operation connected to an emulator and subsequently to a real photovoltaic module are also given.
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Pressure management (PM) is commonly used in water distribution systems (WDSs). In the last decade, a strategic objective in the field has been the development of new scientific and technical methods for its implementation. However, due to a lack of systematic analysis of the results obtained in practical cases, progress has not always been reflected in practical actions. To address this problem, this paper provides a comprehensive analysis of the most innovative issues related to PM. The methodology proposed is based on a case-study comparison of qualitative concepts that involves published work from 140 sources. The results include a qualitative analysis covering four aspects: (1) the objectives yielded by PM; (2) types of regulation, including advanced control systems through electronic controllers; (3) new methods for designing districts; and (4) development of optimization models associated with PM. The evolution of the aforementioned four aspects is examined and discussed. Conclusions regarding the current status of each factor are drawn and proposals for future research outlined
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The paper we present is part of the research project "The professional identity of teacher studies", that we are development for last 3 years. The third phase of this research put the focus on the experience of job placement of novel teachers, graduated no more than 5 years. We work with focal groups and professional experience and teacher education accounts of teachers implied in this research. Also, for any teachers, we do biographical interviews to deepen on processes of construction of professional identity. In this paper we present the Ana Belen History, a female teacher of pre-school education with an experience of 4 years in school, working in a urban school with students in risk of exclusion. This school have a educative project, commitment with the neighbourhood, joint with the community and other social groups. Ana Belen story, from professional perspective, is linked with the social politic and educational commitment of this school. Our interest is focused in the comprehension of professional identity that Ana Belen has gone forging along her personal story and how her education and job placement has contributed for it. Also we are interested in knowing how early professional experiences have influenced in her professional development as teacher. Specifically we ask ourselves about what influence have for her professional identity, that her career starts in this particular school. In consequence, this paper leads us to question the current teacher education model. In particular we are interested on the kind of professional experience that have place and, so, the kinds of commitments that enables. We understand that frameworks in which professional education and experience have place are relevant to enable more or less transformer understandings about teaching. From conceptual perspective this paper adopts a socio-critical point of view (Gergen, 1985; Kincheloe, 2001; Wenger, 1988, etc.). We understand that teaching has to be analysing according work contexts and personal stories of teachers, because we face processes historical and collective building. Teaching is the result of action of their actors, over time, and in specific stage. So, with this research we intend to break with the old gap between pre and in-service education. We think that both of them are part of the same process and are formed according similar logical; although scenes change. We understand that they are part of a continuous process in which is giving sense to different and complex settings where teaching profession is built, but they are not differenced and independent stages. The teacher work, so, is subject to particular conditions, generated from such different fields as institutional, corporative, cultural, social, political, moral, etc. It displays a kaleidoscopic view on space, time, context, ... These are the axis in which the teaching is formed, from the complexity and heterogeneity. How this complexity is articulated results in different ways to face the teacher work, according different personal and professional stories. The teacher acts with subjects in instituted contexts from relationships he has with them, which gives a situated and contingent character. But, these contexts are strongly structured and ruled according centralized and generalized positions; which is, at the very least, paradoxical. Possibly, from our point of view, same of the crisis of teaching have to explain from this paradoxical perspective and the conflict, which characterize this job (Rivas, Leite y Cortés, 2011)
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Consumers currently enjoy a surplus of goods (books, videos, music, or other items) available to purchase. While this surplus often allows a consumer to find a product tailored to their preferences or needs, the volume of items available may require considerable time or effort on the part of the user to find the most relevant item. Recommendation systems have become a common part of many online business that supply users books, videos, music, or other items to consumers. These systems attempt to provide assistance to consumers in finding the items that fit their preferences. This report presents an overview of recommendation systems. We will also briefly explore the history of recommendation systems and the large boost that was given to research in this field due to the Netflix Challenge. The classical methods for collaborative recommendation systems are reviewed and implemented, and an examination is performed contrasting the complexity and performance among the various models. Finally, current challenges and approaches are discussed.