946 resultados para Turning moment


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A historiografia sobre o período colonial na Amazônia supõe uma realidade moldada pela oposição entre um projeto colonial agrícola e a ocorrência de situações concretas de economias extrativistas, a depender da disponbilidade de capital a ser aplicado no principal meio de produção, o escravo negro. De modo que um longo período de escassez de recursos teria conformado o ciclo da economia extrativista na Região dominado pelas "drogas do sertão", substituído por esforços da gestão pombalina por um ciclo agrícola. A gestão pombalina seria a inflexão para uma dinâmica estruturada pela agricultura que, alimentada adiante por conjunturas do mercado mundial, sobretudo as ligadas à guerra da independência americana, só encontraria limitação importante na emergência do novo ciclo extrativista centrado na borracha. Os resultados aqui discutidos não demonstram ser a período pombalino o momento em que, enfim, se estabeleceram os fundamentos da economia amazônica. Trata-se, na verdade, de fundamental e criativo momento de uma trajetória que, todavia, já iniciara quase ¾ de século antes, se impôs ao protagonismo reformador que marcou o período e dele recebeu condicionantes que marcaram indelevelmente a história da Região até os dias atuais.

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O presente estudo sobre o trabalho escravo está pautado na análise dos princípios gerais e constitucionais que norteiam a matéria, em especial, o princípio da dignidade humana, discutindo principalmente as hipóteses caracterizadoras do crime de redução do trabalhador à condição análoga à de escravo, os bens jurídicos tutelados, e as possíveis formas de combater essa prática. A partir desse referencial, aprofundamos a pesquisa nas formas de atuação preventiva do Estado, como meio de propiciar a inclusão social dos trabalhadores. Ao abordar a problemática do trabalho escravo, buscamos discutir mecanismos de inclusão social, por meio de ações capazes de inibir a prática do trabalho escravo no momento do aliciamento da mão-de-obra. Esta pesquisa tem por finalidade principal chamar a atenção para o problema que vivenciamos ainda hoje no meio rural brasileiro, demonstrando a necessidade de se agir efetivamente contra esta prática secular que é submeter o ser humano a condições subumanas de vida, por meio da superexploração do trabalho, com vistas a coibir este crime desde o momento do aliciamento, e não apenas por meio de ações repressivas como o resgate. Em outras palavras, defendemos a necessidade de atuação no momento a priori da escravidão – na arregimentação. O estudo está dividido em três capítulos, o primeiro destina-se à compreensão teórico-jurídica do trabalho escravo, analisando o crime sob as óticas internacional, constitucional e penalista; o segundo trata da análise das formas de atuação repressiva do Estado, trazendo entendimentos jurisprudenciais trabalhistas e penais a respeito do tema, cujas decisões judiciais foram selecionadas principalmente no Estado do Pará; e o terceiro capítulo traz o estudo de métodos de atuação preventiva, como forma de combate ao trabalho escravo e de promoção da inclusão social, percorrendo detalhadamente as características do aliciamento ilegal de trabalhadores, propondo, ao final, a regularização prévia da relação de trabalho, transformando o aliciamento ilegal em contrato de trabalho regular.

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A possible way for increasing the cutting tool life can be achieved by heating the workpiece in order to diminish the shear stress of material and thus decrease the machining forces. In this study, quartz electrical resistances were set around the workpiece for heating it during the turning. In the tests, heat-resistant austenitic alloy steel was used, hardenable by precipitation, mainly used in combustion engine exhaustion valves, among other special applications for industry. The results showed that in the hot machining the cutting tool life can be increased by 340% for the highest cutting speed tested and had a reduction of 205% on workpiece surface roughness, accompanied by a force decrease in relation to conventional turning. In addition, the chips formed in hot turning exhibited a stronger tendency to continuous chip formation indicating less energy spent in material removal process. Microhardness tests performed in the workpieces subsurface layers at 5 m depth revealed slightly higher values in the hot machining than in conventional, showing a tendency toward the formation of compressive residual stress into plastically deformed layer. The hot turning also showed better performance than machining using cutting fluid. Since it is possible to avoid the use of cutting fluid, this machining method can be considered better for the environment and for the human health.

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Background: Cardiovascular disease is an important cause of death in patients on dialysis. Peripheral arterial disease (PAD) is a prognostic factor for cardiovascular disease. The ankle brachial index (ABI) is a noninvasive method used for the diagnosis of PAD. The difference between ABI pre- and post-dialysis had not yet been formally tested, and it was the main objective of this study. Methods:The ABI was assessed using an automated oscillometric device in incident patients on hemodialysis. All blood pressure readings were taken in triplicate pre- and post-dialysis in three consecutive dialysis sessions (times 1, 2, and 3). Results: One hundred and twenty-three patients (85 men) aged 53 +/- 19 years were enrolled. We found no difference in ABI pre- and post-dialysis on the right or left side, and there was no difference in times 1, 2, and 3. In patients with a history of PAD, the ABI pre- versus post-dialysis were of borderline significance on the right side (p = 0.088). Conclusion: ABI measured pre- and post-dialysis presented low variability. The ABI in patients with a history of PAD should be evaluated with caution. The applicability of the current method in predicting mortality among patients on hemodialysis therefore needs further investigation. Copyright (C) 2012 S. Karger AG, Basel

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Upper bounds on fundamental length are discussed that follow from the fact that a magnetic moment is inherent in a charged particle in noncommutative (NC) electrodynamics. The strongest result thus obtained for the fundamental length is still larger than the estimate of electron or muon size achieved following the Brodsky-Drell and Dehlmet approach to lepton compositeness. This means that NC electrodynamics cannot alone explain the whole existing discrepancy between the theoretical and experimental values of the muon magnetic moment. On the contrary, as measurements and calculations are further improved, the fundamental length estimate based on electron data may go down to match its compositeness radius.

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We study a strongly interacting "quantum dot 1" and a weakly interacting "dot 2" connected in parallel to metallic leads. Gate voltages can drive the system between Kondo-quenched and non-Kondo free-moment phases separated by Kosterlitz-Thouless quantum phase transitions. Away from the immediate vicinity of the quantum phase transitions, the physical properties retain signatures of first-order transitions found previously to arise when dot 2 is strictly noninteracting. As interactions in dot 2 become stronger relative to the dot-lead coupling, the free moment in the non-Kondo phase evolves smoothly from an isolated spin-one-half in dot 1 to a many-body doublet arising from the incomplete Kondo compensation by the leads of a combined dot spin-one. These limits, which feature very different spin correlations between dot and lead electrons, can be distinguished by weak-bias conductance measurements performed at finite temperatures.

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The objective of this paper is to show the dependence relationship between the crystallographic orientations upon brittle-to-ductile transition during diamond turning of monocrystalline silicon. Cutting tests were performed using a -5 degrees rake angle round nose diamond tool at different machining scales. At the micrometre level, the feedrate was kept constant at 2.5 micrometres per revolution (mu m/r), and the depth of cut was varied from 1 to 5 mu m. At the submicrometre level, the depth of cut was kept constant at 500 nm and the feedrate varied from 5 to 10 mu m/r. At the micrometre level, the uncut shoulder generated with an interrupted cutting test procedure provided a quantitative measurement of the ductile-to-brittle transition. Results show that the critical chip thickness in silicon for ductile material removal reaches a maximum of 285 nm in the [100] direction and a minimum of 115 nm in the [110] direction, when the depth of cut was 5 mu m. It was found that when a submicrometre depth of cut was applied, microcracks were revealed in the [110] direction, which is the softer direction in silicon. Micro Raman spectroscopy was used to estimate surface residual stress after machining. Compressive residual stress in the range 142 MPa and smooth damage free surface finish was probed in the [100] direction for a depth of cut of 5 mu m, whereas residual stresses in the range 350 MPa and brittle damage was probed in the [110] direction for a depth of cut of 500 nm.

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The molecular method is used to obtain nuclear electric quadrupole moment (NQM) values for hafnium through electric field gradients (EFGs) at this nucleus in HfO and HfS. Dirac-Coulomb calculations with the Coupled Cluster approach, DC-CCSD (T) and DC-CCSD-T, were carried out to achieve the most accurate estimates of these EFGs. Higher order corrections are also added. Hence, the most reliable values for 177Hf and 179Hf determined here are 3319(33) and 3750(37) mbarn, respectively, in nice accordance with the best currently accepted NQMs for this element. (C) 2012 Elsevier B.V. All rights reserved.