100 resultados para Brakes.


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In the first year and a half of its existence, the EEAS and its head have become the target of extensive criticism for the shortcomings of EU foreign policy; shortcomings that in fact date back to the creation of the European Union. The EU’s diplomatic service has been blamed variously for ‘lacking clarity,’ ‘acting too slowly’ and ‘being unable to bridge the institutional divide’. In this Commentary author Hrant Kostanyan argues that the EEAS’ discretionary power in the Eastern Partnership multilateral framework is restricted by the decision-making procedures between a wide range of stakeholders: the member states and the partner countries, as well as by the EU institutions, international organisations and the Civil Society Forum. Since this decision-making process places a substantial number of brakes on the discretionary power of the EEAS, any responsible analysis or critique of the service should take these constraints into consideration. Ultimately, the EEAS is only able to craft EU foreign policy insofar as it is allowed to do so.

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A person with a moderate or severe motor disability will often use specialised or adapted tools to assist their interaction with a general environment. Such tools can assist with the movement of a person's arms so as to facilitate manipulation, can provide postural supports, or interface to computers, wheelchairs or similar assistive technologies. Designing such devices with programmable stiffness and damping may offer a better means for the person to have effective control of their surroundings. This paper addresses the possibility of designing some assistive technologies using impedance elements that can adapt to the user and the circumstances. Two impedance elements are proposed. The first, based on magnetic particle brakes, allows control of the damping coefficient in a passive element. The second, based on detuning the P-D controller in a servo-motor mechanism, allows control of both stiffness and damping. Such a mechanical impedance can be modulated to the conditions imposed by the task in hand. The limits of linear theory are explored and possible uses of programmable impedance elements are proposed.

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Rationale: Major coronary vessels derive from the proepicardium, the cellular progenitor of the epicardium, coronary endothelium, and coronary smooth muscle cells (CoSMCs). CoSMCs are delayed in their differentiation relative to coronary endothelial cells (CoEs), such that CoSMCs mature only after CoEs have assembled into tubes. The mechanisms underlying this sequential CoE/CoSMC differentiation are unknown. Retinoic acid (RA) is crucial for vascular development and the main RA-synthesizing enzyme is progressively lost from epicardially derived cells as they differentiate into blood vessel types. In parallel, myocardial vascular endothelial growth factor (VEGF) expression also decreases along coronary vessel muscularization. Objective: We hypothesized that RA and VEGF act coordinately as physiological brakes to CoSMC differentiation. Methods and Results: In vitro assays (proepicardial cultures, cocultures, and RALDH2 [retinaldehyde dehydrogenase-2]/VEGF adenoviral overexpression) and in vivo inhibition of RA synthesis show that RA and VEGF act as repressors of CoSMC differentiation, whereas VEGF biases epicardially derived cell differentiation toward the endothelial phenotype. Conclusion: Experiments support a model in which early high levels of RA and VEGF prevent CoSMC differentiation from epicardially derived cells before RA and VEGF levels decline as an extensive endothelial network is established. We suggest this physiological delay guarantees the formation of a complex, hierarchical, tree of coronary vessels. (Circ Res. 2010;107:204-216.)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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In engineering practical systems the excitation source is generally dependent on the system dynamic structure. In this paper we analyze a self-excited oscillating system due to dry friction which interacts with an energy source of limited power supply (non ideal problem). The mechanical system consists of an oscillating system sliding on a moving belt driven by a limited power supply. In the oscillating system considered here, dry friction acts as an excitation mechanism for stick-slip oscillations. The stick-slip chaotic oscillations are investigated because the knowledge of their dynamic characteristics is an important step in system design and control. Many engineering systems present stick-slip chaotic oscillations such as machine tools, oil well drillstrings, car brakes and others.

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Automotive parts manufacture by machining process using silicon nitride-based ceramic tool development in Brazil already is a reality. Si 3N4-based ceramic cutting tools offer a high productivity due to their excellent hot hardness, which allows high cutting speeds. Under such conditions the cutting tool must be resistant to a combination of mechanical, thermal and chemical attacks. Silicon nitride based ceramic materials constitute a mature technology with a very broad base of current and potential applications. The best opportunities for Si3N 4-based ceramics include ballistic armor, composite automotive brakes, diesel particulate filters, joint replacement products and others. The goal of this work was to show latter advance in silicon nitride manufacture and its recent evolution on machining process of gray cast iron, compacted graphite iron and Ti-6Al-4V. Materials characterization and machining tests were analyzed by X-Ray Diffraction, Scanning Electron Microscopy, Vickers hardness and toughness fracture and technical norm. In recent works the authors has been proved to advance in microstructural, mechanical and physic properties control. These facts prove that silicon nitride-based ceramic has enough resistance to withstand the impacts inherent to the machining of gray cast iron (CI), compacted graphite iron (CGI) and Ti-6Al-4V (6-4). Copyright © 2008 SAE International.

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Includes bibliography

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The brake system of a Formula SAE car has determinant character in the quality of the project. Any flaw in the design of the brakes, the vehicle is rejected for the competition. The project well done, and its smooth operation, depends on some variables that should be studied and linked to the brake components, as needed by the vehicle. After the calculations, the components were defined according to commercial availability. So it is interesting simulation of braking when the vehicle will be submitted before the implementation of the brake system, saving time and cost. This project also enable the comparison between components from different brands. This work shows the study of a method that would allow simulate and test the brake system in an upcoming project for a bench test

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The automobilist Market is more competitive each day, with new products developed by great technological innovations, daily challenging new concepts of Engineering. This monograph aims to explain the development of a brake system project completely, with emphasis on preliminary calculations made from a worksheet in Excel, for a better understanding of the components, which can be improved further in order to achieve the goals of company. It is through the preliminary calculations that we can have a reasonable first system estimate. The whole set is then analyzed for performance, cost and mass by competitors benchmarking. In terms of confidentiality, all data is fictional, but viable. The motivation for this study is approach an extracurricular topic, which essence is designing, base of engineering. The results obtained in software and field tests prove the validity of the study and assist in the continuous improvement of product development

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This study explores the subject of traction control systems through bibliografy review on the spot of Mechanical Engineering. This paper has the objetivo of high light the main components and tecnology involved since MaxTrac system in 1971. It describes systems controled by throttle valve and breaks. Additionally, it i also presented basic knowlodged regarding electronic control unit and wheel sensors

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)