940 resultados para circuits and Systems


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"Seventeen peer-reviewed papers cover the latest research on the ignition and combustion of metals and non-metals, oxygen compatibility of components and systems, analysis of ignition and combustion, failure analysis and safety. It includes aerospace, military, scuba diving, and industrial oxygen applications. Topics cover: • Development of safe oxygen systems • Ignition mechanisms within oxygen systems and how to avoid them • Specific hazards that exist with the oxygen mixture breathed by divers in the scuba industry • Issues related to oxygen system level safety • Issues related to oxygen safety in breathing systems • Detailed investigations and discussions related to the burn curves that have been generated for metals that are burning in a standard test fixture This new publication is a valuable resource for professionals in the air separation industries, oxygen manufacturers, manufacturers of materials intended for oxygen service, and users of oxygen and oxygen-enriched atmospheres, including aerospace, medical, industrial gases, chemical processing, steel and metals refining, as well as to military, commercial or recreational diving."--- publisher website

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This paper presents practical vision-based collision avoidance for objects approximating a single point feature. Using a spherical camera model, a visual predictive control scheme guides the aircraft around the object along a conical spiral trajectory. Visibility, state and control constraints are considered explicitly in the controller design by combining image and vehicle dynamics in the process model, and solving the nonlinear optimization problem over the resulting state space. Importantly, range is not required. Instead, the principles of conical spiral motion are used to design an objective function that simultaneously guides the aircraft along the avoidance trajectory, whilst providing an indication of the appropriate point to stop the spiral behaviour. Our approach is aimed at providing a potential solution to the See and Avoid problem for unmanned aircraft and is demonstrated through a series.

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This paper takes its root in a trivial observation: management approaches are unable to provide relevant guidelines to cope with uncertainty, and trust of our modern worlds. Thus, managers are looking for reducing uncertainty through information’s supported decision-making, sustained by ex-ante rationalization. They strive to achieve best possible solution, stability, predictability, and control of “future”. Hence, they turn to a plethora of “prescriptive panaceas”, and “management fads” to bring simple solutions through best practices. However, these solutions are ineffective. They address only one part of a system (e.g. an organization) instead of the whole. They miss the interactions and interdependencies with other parts leading to “suboptimization”. Further classical cause-effects investigations and researches are not very helpful to this regard. Where do we go from there? In this conversation, we want to challenge the assumptions supporting the traditional management approaches and shed some lights on the problem of management discourse fad using the concept of maturity and maturity models in the context of temporary organizations as support for reflexion. Global economy is characterized by use and development of standards and compliance to standards as a practice is said to enable better decision-making by managers in uncertainty, control complexity, and higher performance. Amongst the plethora of standards, organizational maturity and maturity models hold a specific place due to general belief in organizational performance as dependent variable of (business) processes continuous improvement, grounded on a kind of evolutionary metaphor. Our intention is neither to offer a new “evidence based management fad” for practitioners, nor to suggest research gap to scholars. Rather, we want to open an assumption-challenging conversation with regards to main stream approaches (neo-classical economics and organization theory), turning “our eyes away from the blinding light of eternal certitude towards the refracted world of turbid finitude” (Long, 2002, p. 44) generating what Bernstein has named “Cartesian Anxiety” (Bernstein, 1983, p. 18), and revisit the conceptualization of maturity and maturity models. We rely on conventions theory and a systemic-discursive perspective. These two lenses have both information & communication and self-producing systems as common threads. Furthermore the narrative approach is well suited to explore complex way of thinking about organizational phenomena as complex systems. This approach is relevant with our object of curiosity, i.e. the concept of maturity and maturity models, as maturity models (as standards) are discourses and systems of regulations. The main contribution of this conversation is that we suggest moving from a neo-classical “theory of the game” aiming at making the complex world simpler in playing the game, to a “theory of the rules of the game”, aiming at influencing and challenging the rules of the game constitutive of maturity models – conventions, governing systems – making compatible individual calculation and social context, and possible the coordination of relationships and cooperation between agents with or potentially divergent interests and values. A second contribution is the reconceptualization of maturity as structural coupling between conventions, rather than as an independent variable leading to organizational performance.

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How do agents with limited cognitive capacities flourish in informationally impoverished or unexpected circumstances? Aristotle argued that human flourishing emerged from knowing about the world and our place within it. If he is right, then the virtuous processes that produce knowledge, best explain flourishing. Influenced by Aristotle, virtue epistemology defends an analysis of knowledge where beliefs are evaluated for their truth and the intellectual virtue or competences relied on in their creation. However, human flourishing may emerge from how degrees of ignorance are managed in an uncertain world. Perhaps decision-making in the shadow of knowledge best explains human wellbeing—a Bayesian approach? In this dissertation I argue that a hybrid of virtue and Bayesian epistemologies explains human flourishing—what I term homeostatic epistemology. Homeostatic epistemology supposes that an agent has a rational credence p when p is the product of reliable processes aligned with the norms of probability theory; whereas an agent knows that p when a rational credence p is the product of reliable processes such that: 1) p meets some relevant threshold for belief (such that the agent acts as though p were true and indeed p is true), 2) p coheres with a satisficing set of relevant beliefs and, 3) the relevant set of beliefs is coordinated appropriately to meet the integrated aims of the agent. Homeostatic epistemology recognizes that justificatory relationships between beliefs are constantly changing to combat uncertainties and to take advantage of predictable circumstances. Contrary to holism, justification is built up and broken down across limited sets like the anabolic and catabolic processes that maintain homeostasis in the cells, organs and systems of the body. It is the coordination of choristic sets of reliably produced beliefs that create the greatest flourishing given the limitations inherent in the situated agent.

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This paper explores the rationale, experience and impact of thirteen Australia and New Zealand universities that have integrated the Engineers Without Borders (EWB) challenge into their first year engineering curriculum. EWB is a national competition for university students, who work in teams to develop conceptual designs for real sustainable development projects across the globe. This project investigated “what works and what doesn’t” in engineering curriculum renewal, utilising content analysis, multiple in-depth interviews with students and staff (coordinators, lecturers, tutors) and observation. EWB comprises between 25 to 100% of the total assessment items. This paper specifically focuses on student’s experience of EWB, documenting how the project teaches sustainability and systems-thinking approaches, engages students with different cultures, and fosters teamwork, new ways of thinking and communication skills. We identify key benefits and challenges of EWB, as well as mechanisms and contexts that foster student engagement and learning outcomes.

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A renewal of interest has occurred in the relationship between religion, penal policy, and systems of criminal justice in different countries. This has been manifested in the development of religious programmes in prison and community settings. The subject has also precipitated a substantial body of empirical research, in addition to theorising the impacts of religion upon offending behaviour. However, specific faith‐based measures have attracted limited attention, mainly because of the empirical complexity of measuring the relationship between faith and behavioural change. These issues are addressed in this article by considering the recentlyemerged practice of Circles of Support and Accountability (COSA).

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Do you need a practical guide to assessment, curriculum and policy? Are you also looking for a book that is firmly grounded in the theory of this subject? Assessment for Education combines both theory and practice, making it the perfect guide for students, researchers, academics and teachers. This book makes assessment processes transparent for practitioners, and shows how assessment should relate to education. It looks at evidence-informed decision-making and the interrelationships between standards, judgment and moderation practice for improved assessment, teacher quality, schools and systems. The book will provide you with: ' Knowledge about quality assessment and judgement practice ' Understanding of relationships across curriculum, assessment, teaching and learning ' Knowledge of the concept of front-ending assessment based on the learner's needs ' An analysis of practitioner judgement approaches ' Understanding of the conditions under which teacher assessment can be valid ' Principles derived from research of social moderation practices Whether you are studying and researching assessment or working in curriculum and assessment policy, this book will show you how practitioner use of achievement standards can improve learning, equity, social justice and accountability.

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Significant problems confront our child protection out-of-home care system including: high costs; increasing numbers of children and young people entering and remaining in care longer; high frequency of placement movement; and, negative whole-of-life outcomes for children and young people who have exited care. National policy and research agendas recognise the importance of enhancing the evidence base in out-of-home care to inform the development of policy, programs and practice, and improve longitudinal outcomes of children and young people. The authors discuss the concept of placement trajectory as a framework for research and systems analysis in the out-of-home context. While not without limitations, the concept of placement trajectory is particularly useful in understanding the factors influencing placement movement and stability. Increasing the evidence base in this area can serve to enhance improved outcomes across the lifespan for children and young people in the out-of-home care system.

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Fusion techniques can be used in biometrics to achieve higher accuracy. When biometric systems are in operation and the threat level changes, controlling the trade-off between detection error rates can reduce the impact of an attack. In a fused system, varying a single threshold does not allow this to be achieved, but systematic adjustment of a set of parameters does. In this paper, fused decisions from a multi-part, multi-sample sequential architecture are investigated for that purpose in an iris recognition system. A specific implementation of the multi-part architecture is proposed and the effect of the number of parts and samples in the resultant detection error rate is analysed. The effectiveness of the proposed architecture is then evaluated under two specific cases of obfuscation attack: miosis and mydriasis. Results show that robustness to such obfuscation attacks is achieved, since lower error rates than in the case of the non-fused base system are obtained.

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Motion planning for planetary rovers must consider control uncertainty in order to maintain the safety of the platform during navigation. Modelling such control uncertainty is difficult due to the complex interaction between the platform and its environment. In this paper, we propose a motion planning approach whereby the outcome of control actions is learned from experience and represented statistically using a Gaussian process regression model. This model is used to construct a control policy for navigation to a goal region in a terrain map built using an on-board RGB-D camera. The terrain includes flat ground, small rocks, and non-traversable rocks. We report the results of 200 simulated and 35 experimental trials that validate the approach and demonstrate the value of considering control uncertainty in maintaining platform safety.

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This work aims to promote integrity in autonomous perceptual systems, with a focus on outdoor unmanned ground vehicles equipped with a camera and a 2D laser range finder. A method to check for inconsistencies between the data provided by these two heterogeneous sensors is proposed and discussed. First, uncertainties in the estimated transformation between the laser and camera frames are evaluated and propagated up to the projection of the laser points onto the image. Then, for each pair of laser scan-camera image acquired, the information at corners of the laser scan is compared with the content of the image, resulting in a likelihood of correspondence. The result of this process is then used to validate segments of the laser scan that are found to be consistent with the image, while inconsistent segments are rejected. Experimental results illustrate how this technique can improve the reliability of perception in challenging environmental conditions, such as in the presence of airborne dust.

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The complex systems approach offers an opportunity to replace the extant pre-dominant mechanistic view on sport-related phenomena. The emphasis on the environment-system relationship, the applications of complexity principles, and the use of nonlinear dynamics mathematical tools propose a deep change in sport science. Coordination dynamics, ecological dynamics, and network approaches have been successfully applied to the study of different sport-related behaviors, from movement patterns that emerge at different scales constrained by specific sport contexts to game dynamics. Sport benefit from the use of such approaches in the understanding of technical, tactical, or physical conditioning aspects which change their meaning and dilute their frontiers. The creation of new learning and training strategies for teams and individual athletes is a main practical consequence. Some challenges for the future are investigating the influence of key control parameters in the nonlinear behavior of athlete-environment systems and the possible relatedness of the dynamics and constraints acting at different spatio-temporal scales in team sports. Modelling sport-related phenomena can make useful contributions to a better understanding of complex systems and vice-versa.

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This edition of ALARj has a focus on the contribution of action learning and action research to the development of community services, particularly nonprofits. The landscape of community services has been changing rapidly in recent decades, and can be typified by the notion of complexity. Complexity in the nature of issues that services seek to respond to, complexity in the policy environment and systems of support that have tended to silo and compartmentalise problems and people, and complexity in the institutional location non-profit services occupy in ‘helping’ those who are seen as ‘in need’ or marginalised. In addition to being typified by complexity the environment in which community services are located is dynamic, undergoing profound and ongoing change as neo-liberal approaches to understanding and responding to human need, which emphasise the individualisation of risk, and market principles such as choice, competition and innovation, drive social policy. How can long held values of empowerment, care, inclusivity and benefit to individuals and communities have expression in community services as they grapple with the challenges of being viable and relevant in such a dynamically changing environment? This edition brings together a range of contributions which speak to these challenges. The thematic through these is that processes are needed which engage services and communities in ongoing processes of inquiry about how they can best proceed in contexts typified by complexity and change. Action learning and action research can provide processes of this character.

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Purpose This paper aims to present key findings from an inquiry into engineering accreditation and curricula renewal. The research attempted to ascertain conceptions of requisite sustainability themes among engineering academics and professionals. The paper also reflects on the potential role of professional engineering institutions (PEIs) in embedding sustainability through their programme accreditation guidelines and wider implications in terms of rapid curricula renewal. Design/methodology/approach This research comprised an International Engineering Academic Workshop held during the 2010 International Symposium on Engineering Education in Ireland, on “accreditation and sustainable engineering”. This built on the findings of a literature review that was distributed prior to the workshop. Data collection included individual questionnaires administered during the workshop, and notes scribed by workshop participants. Findings The literature review highlighted a wide range of perspectives across and within engineering disciplines, regarding what sustainability/sustainable development (SD) themes should be incorporated into engineering curricula, and regarding language and terminology. This was also reflected in the workshop discussions. Notwithstanding this diversity, clusters of sustainability themes and priority considerations were distilled from the literature review and workshop. These related to resources, technology, values, ethics, inter- and intra-generational equity, transdisciplinarity, and systems and complex thinking. Themes related to environmental and economic knowledge and skills received less attention by workshop participants than represented in the literature. Originality/value This paper provides an appreciation of the diversity of opinion regarding priority sustainability themes for engineering curricula, among a group of self-selected engineering academics who have a common interest in education for SD. It also provides some insights and caveats on how these themes might be rapidly integrated into engineering curricula.

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Protein arginine methyltransferases (PRMTs) methylate arginine residues on histones and target transcription factors that play critical roles in many cellular processes, including gene transcription, mRNA splicing, proliferation, and differentiation. Recent studies have linked PRMT-dependent epigenetic marks and modifications to carcinogenesis and metastasis in cancer. However, the role of PRMT2-dependent signaling in breast cancer remains obscure. We demonstrate PRMT2 mRNA expression was significantly decreased in breast cancer relative to normal breast. Gene expression profiling, Ingenuity and protein-protein interaction network analysis after PRMT2-short interfering RNA transfection into MCF-7 cells, revealed that PRMT2-dependent gene expression is involved in cell-cycle regulation and checkpoint control, chromosomal instability, DNA repair, and carcinogenesis. For example, PRMT2 depletion achieved the following: 1) increased p21 and decreased cyclinD1 expression in (several) breast cancer cell lines, 2) decreased cell migration, 3) induced an increase in nucleotide excision repair and homologous recombination DNA repair, and 4) increased the probability of distance metastasis free survival (DMFS). The expression of PRMT2 and retinoid-related orphan receptor-γ (RORγ) is inversely correlated in estrogen receptor-positive breast cancer and increased RORγ expression increases DMFS. Furthermore, we found decreased expression of the PRMT2-dependent signature is significantly associated with increased probability of DMFS. Finally, weighted gene coexpression network analysis demonstrated a significant correlation between PRMT2-dependent genes and cell-cycle checkpoint, kinetochore, and DNA repair circuits. Strikingly, these PRMT2-dependent circuits are correlated with pan-cancer metagene signatures associated with epithelial-mesenchymal transition and chromosomal instability. This study demonstrates the role and significant correlation between a histone methyltransferase (PRMT2)-dependent signature, RORγ, the cell-cycle regulation, DNA repair circuits, and breast cancer survival outcomes.