951 resultados para Degrees of freedom (mechanics)


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First-order transitions of system where both lattice site occupancy and lattice spacing fluctuate, such as cluster crystals, cannot be efficiently studied by traditional simulation methods, which necessarily fix one of these two degrees of freedom. The difficulty, however, can be surmounted by the generalized [N]pT ensemble [J. Chem. Phys. 136, 214106 (2012)]. Here we show that histogram reweighting and the [N]pT ensemble can be used to study an isostructural transition between cluster crystals of different occupancy in the generalized exponential model of index 4 (GEM-4). Extending this scheme to finite-size scaling studies also allows us to accurately determine the critical point parameters and to verify that it belongs to the Ising universality class.

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Tree planting is one of the most physically demanding occupations in Canada and as a result, tree planters are at an elevated risk of injury, specifically at the wrist. Wrist injuries develop on account of the highly repetitive nature of the job, as well as other musculoskeletal risk factors including non-neutral wrist postures and high impact forces sustained at the wrist during shovel-ground impact. As a result, wrist brace use has become common among planters, in an effort to limit deviated wrist postures while also providing enhanced stability at the wrist. The external stability provided by a wrist brace is thought to reduce the muscular effort required to provide stiffness at the wrist during shovel-ground impact. Since these prospective benefits have not been formally investigated, the purpose of this study was to determine the effect of a wrist brace on wrist posture, muscle activity, and joint rotational stiffness about the wrist joint (for two degrees of freedom: flexion/extension and ulnar/radial deviation). We hypothesized that the brace would promote more neutrally aligned wrist angles, and that muscle activity and joint rotational stiffness would also decrease when participants wore the brace. Fourteen tree planters with at least one season of experience were recruited to complete two planting conditions in a laboratory setting: one condition while wearing the brace (with brace, WB) and one condition without the brace (no brace, NB). The results from this study showed that at shovel-ground impact muscle activity trended towards increasing in three muscles when participants wore the brace. Additionally, wrist angles improved about the flexion/extension axis of rotation while increasing in deviation about the ulnar/radial axis of rotation when participants wore the brace. Joint rotational stiffness increased when participants wore the wrist brace. Participants from this study indicated difficulty gripping the shovel due to the bulk of the wrist brace, and this feature is discussed with possible suggestions for future iterations of design. In addition to grip diameter this analysis also prompts the suggestion that hand length and experience should also be considered in the design of tree planting tools, specifically an ergonomic aid such as a wrist brace.

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In this paper I discuss one of the most significant strategies in Spinoza’s theoretical approach against those that entrave its understanding in a very powerful way. As well as Descartes, Spinoza uses the inmediate or unreflexive experience for developing his conception of free will or the distinction between body and soul, but he does so in order to prove that the experience is useful to demonstrate some purely anti-Cartesian thesis that express the core principles of Spinozism.

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the article explores the putatively non-metaphysical – non-voluntarist, and even non-causal – concept of freedom outlined in Hegel’s work and discusses its influential interpretation by robert Pippin as an ‘essentially practical’ concept. I argue that Hegel’s affirmation of freedom must be distinguished from that of Kant and Fichte, since it does not rely on a prior understanding of self-consciousness as an originally teleological relation and it has not the nature of a claim ‘from a practical point of view’.

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Extended contribution to a roundtable on Mark A. Lause's Free Labor: The Civil War and the Making of an American Working Class, emphasizing the wartime labor movement's great difficulty in responding to rapid industrialization brought on by the war, and to the increasing diversity of the labor force brought about by mass immigration.

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Thesis (Master's)--University of Washington, 2016-06

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This essay addresses the fundamental conceptual challenges which face the development of the Area of Freedom Security and Justice (AFSJ) in the post-Lisbon Treaty era. It argues that Onuf style constructivism is a valid lens with which to examine the development of the AFSJ to date, involving as it does the development of a shared understanding by practitioners, predominantly law enforcement and prosecution professionals, within the structures provided for them, in order to develop a completely new area of law and practice. While this approach will continue to need to be deployed in the development of further new operational areas, such as cybercrime, a new approach is now required, that of constitutionalism. A variety of forms of constitutionalism are then examined in order to establish their suitability as a mode of analysis for these developments.

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Small particles and their dynamics are of widespread interest due both to their unique properties and their ubiquity. Here, we investigate several classes of small particles: colloids, polymers, and liposomes. All these particles, due to their size on the order of microns, exhibit significant similarity in that they are large enough to be visualized in microscopes, but small enough to be significantly influenced by thermal (or Brownian) motion. Further, similar optical microscopy and experimental techniques are commonly employed to investigate all these particles. In this work, we develop single particle tracking techniques, which allow thorough characterization of individual particle dynamics, observing many behaviors which would be overlooked by methods which time or ensemble average. The various particle systems are also similar in that frequently, the signal-to-noise ratio represented a significant concern. In many cases, development of image analysis and particle tracking methods optimized to low signal-to-noise was critical to performing experimental observations. The simplest particles studied, in terms of their interaction potentials, were chemically homogeneous (though optically anisotropic) hard-sphere colloids. Using these spheres, we explored the comparatively underdeveloped conjunction of translation and rotation and particle hydrodynamics. Developing off this, the dynamics of clusters of spherical colloids were investigated, exploring how shape anisotropy influences the translation and rotation respectively. Transitioning away from uniform hard-sphere potentials, the interactions of amphiphilic colloidal particles were explored, observing the effects of hydrophilic and hydrophobic interactions upon pattern assembly and inter-particle dynamics. Interaction potentials were altered in a different fashion by working with suspensions of liposomes, which, while homogeneous, introduce the possibility of deformation. Even further degrees of freedom were introduced by observing the interaction of particles and then polymers within polymer suspensions or along lipid tubules. Throughout, while examination of the trajectories revealed that while by some measures, the averaged behaviors accorded with expectation, often closer examination made possible by single particle tracking revealed novel and unexpected phenomena.

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We propose and investigate a hybrid optomechanical system consisting of a micro-mechanical oscillator coupled to the internal states of a distant ensemble of atoms. The interaction between the systems is mediated by a light field which allows the coupling of the two systems in a modular way over long distances. Coupling to internal degrees of freedom of atoms opens up the possibility to employ high-frequency mechanical resonators in the MHz to GHz regime, such as optomechanical crystal structures, and to benefit from the rich toolbox of quantum control over internal atomic states. Previous schemes involving atomic motional states are rather limited in both of these aspects. We derive a full quantum model for the effective coupling including the main sources of decoherence. As an application we show that sympathetic ground-state cooling and strong coupling between the two systems is possible.

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This thesis focuses on experimental and numerical studies of the hydrodynamic interaction between two vessels in close proximity in waves. In the model tests, two identical box-like models with round corners were used. Regular waves with the same wave steepness and different wave frequencies were generated. Six degrees of freedom body motions and wave elevations between bodies were measured in a head sea condition. Three initial gap widths were examined. In the numerical computations, a panel-free method based seakeeping program, MAPS0, and a panel method based program, WAMIT, were used for the prediction of body motions and wave elevations. The computed body motions and wave elevations were compared with experimental data.

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The main goal of LISA Path finder (LPF) mission is to estimate the acceleration noise models of the overall LISA Technology Package (LTP) experiment on-board. This will be of crucial importance for the future space-based Gravitational-Wave (GW) detectors, like eLISA. Here, we present the Bayesian analysis framework to process the planned system identification experiments designed for that purpose. In particular, we focus on the analysis strategies to predict the accuracy of the parameters that describe the system in all degrees of freedom. The data sets were generated during the latest operational simulations organised by the data analysis team and this work is part of the LTPDA Matlab toolbox.

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Objective: To assess depressive symptoms in men deprived from freedom in a prison in a Colombian intermediate city. Material and Method: A cross sectional study was performed on a sample of three hundred and three patients in the Medium Security penitentiary and Prison Facility of the city of Manizales between April and May 2014. The information was collected through the Zung self-rating depression scale (SDS), subsequently there were established the positive results for depression screening according to the final score of the scale. Results: 303 men deprived from freedom were evaluated, mean age of 32.96 years +/- 10.8 years, 43.5% were living in cohabitation, 38% were single and 10.2% married; 33.7% had a primary education, 58% had secondary or incomplete secondary education, 5.6% reported higher studies; 38.6% (95% CI: 35.8; 41.4) reported symptoms of depression, predominating in ages between 18 to 44 years, no statistically significant differences p> 0.05 between the variables analyzed were found. Conclusions: The results of this study give rise to clinical evaluation, by specialized staff in the area of psychiatry and his intervention, given the characteristics of self-reported depression for this population.