497 resultados para Beam theory


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Assessment for Learning is a pedagogical practice with anticipated gains of increased student motivation, mastery and autonomy as learners develop their capacity to monitor and plan their own learning progress. Assessment for Learning (AfL) differs from Assessment of learning in its timing, occurring within the regular flow of learning rather than end point, in its purpose of improving student learning rather than summative grading and in the ownership of the learning where the student voice is heard in judging quality. Since Black and Wiliam (1998) highlighted the achievement gains that AfL practices seem to bring to all learners in classrooms, it has become part of current educational policy discourse in Australia, yet teacher adoption of the practices is not a straightforward implementation of techniques within an existing classroom repertoire. As can be seen from the following meta-analysis, recent research highlights a more complex interrelationship between teacher and student beliefs about learning and assessment, and the social and cultural interactions in and contexts of the classroom. More research is needed from a sociocultural perspective that allows meaning to emerge from practice. Before another policy push, we need to understand better the many factors within the assessment relationship. We need to hear from teachers and students through long-term AfL case studies both to inform AfL theory and to shed light on the complexities of pedagogical change for enhancing learner autonomy.

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Beam steering with high front-to-back ratio and high directivity on a small platform is proposed. Two closely spaced antenna pairs with eigenmode port decoupling are used as the basic radiating elements. Two orthogonal radiation patterns are obtained for each antenna pair. High front-to-back ratio and high directivity are achieved by combining the two orthogonal radiation patterns. With an infinite groundplane, a front-to-back ratio of 21 dB with a directivity of 9.8 dB can be achieved. Beam steering, at the expense of a slight decrease in directivity, is achieved by placing the two antenna pairs 0.5λ apart. The simulated half power beamwidth is 58°. A prototype was designed and the 2-D radiation patterns were measured. The prototype supports three directions of beam steering. The half power beamwidth was measured as 46°, 48°, and 50° for the three respective beam directions. The measured front-to-back ratio in azimuth plane is 8.5 dB, 8.0 dB and 7.6 dB, respectively.

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Levels of waste within the construction industry need to be reduced for environmental and economic reasons. Changing people's wasteful behaviour can make a significant contribution. This paper describes a research project that used Ajzen's 'theory of planned behaviour' to investigate the attitudinal forces that shape behaviour at the operative level. It concludes that operatives see waste as an inevitable by-product of construction activity. Attitudes towards waste management are not negative, although they are pragmatic and impeded by perceptions of a lack of managerial commitment. Waste management is perceived as a low project priority, and there is an absence of appropriate resources and incentives to support it. A theory of waste behaviour is proposed for the construction industry, and recommendations are made to help managers improve operatives' attitudes towards waste.

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This paper offers a reply to Jochen Runde's critical appraisal of the ontological framework underpinning Dopfer and Potts's (2008) General Theory of Economic Evolution. We argue that Runde's comprehensive critique contains several of what we perceive to be misunderstandings in relation to the key concepts of ‘generic’ and ‘meso’ that we seek here to unpack and redress.

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In this study, the delivery and portal imaging of one square-field and one conformal radiotherapy treatment was simulated using the Monte Carlo codes BEAMnrc and DOSXYZnrc. The treatment fields were delivered to a humanoid phantom from different angles by a 6 MV photon beam linear accelerator, with an amorphous-silicon electronic portal imaging device (a-Si EPID) used to provide images of the phantom generated by each field. The virtual phantom preparation code CTCombine was used to combine a computed-tomography-derived model of the irradiated phantom with a simple, rectilinear model of the a-Si EPID, at each beam angle used in the treatment. Comparison of the resulting experimental and simulated a-Si EPID images showed good agreement, within \[gamma](3%, 3 mm), indicating that this method may be useful in providing accurate Monte Carlo predictions of clinical a-Si EPID images, for use in the verification of complex radiotherapy treatments.

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In this paper a new graph-theory and improved genetic algorithm based practical method is employed to solve the optimal sectionalizer switch placement problem. The proposed method determines the best locations of sectionalizer switching devices in distribution networks considering the effects of presence of distributed generation (DG) in fitness functions and other optimization constraints, providing the maximum number of costumers to be supplied by distributed generation sources in islanded distribution systems after possible faults. The proposed method is simulated and tested on several distribution test systems in both cases of with DG and non DG situations. The results of the simulations validate the proposed method for switch placement of the distribution network in the presence of distributed generation.

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Business Process Management (BPM) is a topic that continues to grow in significance as organisations seek to gain and sustain competitive advantage in an increasingly global environment. Despite anecdotal evidence of organisations improving performance by pursuing a BPM approach, there is little theory that explains and substantiates this relationship. This study provides the first theory on the progression and maturity of BPM Initiatives within organisations and provides a vital starting block upon which future research in this area can build. The Researcher starts by clearly defining three key terms (BPM Initiative, BPM Progression and BPM Maturity), showing the relationship between these three concepts and proposing their relationship with Organisational Performance. The Researcher then combines extant literature and use of the Delphi Technique and the case study method to explore the progression and measurement of the BPM Initiatives within organisations. The study builds upon the principles of general theories including the Punctuated Equilibrium Model and Dynamic Capabilities to present theory on BPM Progression and BPM Maturity. Using the BPM Capability Framework developed through an international Delphi study series, the Researcher shows how the specific organisational context influences which capability areas an organisation chooses to progress. By comparing five separate organisations over an extended time the Researcher is able to show that, despite this disparity, there is some evidence of consistency with regard to the capability areas progressed. This suggests that subsequent identification of progression paths may be possible. The study also shows that the approach and scope taken to BPM within each organisation is a likely predictor of such paths. These outcomes result in the proposal of a formative model for measuring BPM Maturity.

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A crucial contemporary policy question for governments across the globe is how to cope with international crime and terrorist networks. Many such “dark” networks—that is, networks that operate covertly and illegally—display a remarkable level of resilience when faced with shocks and attacks. Based on an in-depth study of three cases (MK, the armed wing of the African National Congress in South Africa during apartheid; FARC, the Marxist guerrilla movement in Colombia; and the Liberation Tigers of Tamil Eelam, LTTE, in Sri Lanka), we present a set of propositions to outline how shocks impact dark network characteristics (resources and legitimacy) and networked capabilities (replacing actors, linkages, balancing integration and differentiation) and how these in turn affect a dark network's resilience over time. We discuss the implications of our findings for policymakers.

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There is a lack of writing on the issue of the education rights of people with disabilities by authors of any theoretical persuasion. While the deficiency of theory may be explained by a variety of historical, philosophical and practical considerations, it is a deficiency which must be addressed. Otherwise, any statement of rights rings out as hollow rhetoric unsupported by sound reason and moral rectitude. This paper attempts to address this deficiency in education rights theory by postulating a communitarian theory of the education rights of people with disabilities. The theory is developed from communitarian writings on the role of education in democratic society. The communitarian school, like the community within which it nests, is inclusive. Schools both reflect and model the shape of communitarian society and have primary responsibility for teaching the knowledge and virtues which will allow citizens to belong to and function within society. Communitarians emphasise responsibilities, however, as the corollary of rights and require the individual good to yield to community good when the hard cases arise. The article not only explains the basis of the right to an inclusive education, therefore, but also engages with the difficult issue of when such a right may not be enforceable.