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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Contribuição a melhora das condições ambientais de trabalho através do aprimoramento da iluminação em galpões e pátios cobertos na indústria mineral. / Contribution of environmental work conditions through improvement in lighting in closed stores and sheds in Mineral Industry.

Jaglbauer, Vivien 09 August 2007 (has links)
A questão ambiental e de higiene no trabalho é cada vez mais reconhecida e cobrada pela sociedade civil e pelos órgãos do governo em todas as suas instâncias. Alguns dos pátios de estocagem de minérios, que hoje estão a céu aberto, poderão precisar no futuro serem fechados para atender às normas ambientais cada vez mais rígidas, cobradas pela sociedade através dos órgãos ambientais de controle, que almejam que pátios de armazenamento tenham estanqueidade similar aos silos ou que haja um sistema de contenção de poeira e material particulado eficiente. Uma das saídas viáveis para esta questão é a estocagem do minério em galpões confinados, que demandam um custo de implantação mais elevado mas, que por outro lado, têm um baixo custo operacional. Nos pátios que possuírem fechamento, a iluminação passa a ser uma questão primordial, uma vez que proverá condições de funcionamento à produção, principalmente em caso de trabalho ininterrupto durante 24h. Desta forma, passam a ser consideradas, não somente as questões de segurança, como também de uma iluminação que estimule a produtividade através de um nível maior de iluminância, maior contraste, menor ofuscamento e seja confortável para as tarefas que serão realizadas no ambiente. Em áreas nas quais o material particulado é altamente combustível, tais como pátios de carvão mineral, uma iluminação adequada e segura é questão fundamental, pois se mal projetada, pode ser ignitora de incêndios, explosões e trágicos desastres acometendo trabalhadores e o ambiente de trabalho. Este trabalho é composto por uma extensiva revisão bibliográfica. A primeira parte apresenta os conceitos de iluminação; a segunda trata da higiene e segurança no trabalho, com ênfase no agente físico iluminação. A terceira parte comenta as normas nacionais e internacionais relacionadas à iluminação e analisa às suas solicitações. A quarta parte versa sobre áreas classificadas e atmosferas explosivas, procurando discriminar em linhas simples o que são áreas classificadas, quais os critérios envolvidos, os riscos de ignição de poeiras mais comuns e normas relacionadas a estas áreas. Na quinta parte comenta-se sobre a iluminação de galpões em áreas industriais, relacionando os critérios a serem utilizados para um projeto adequado. Na sexta parte o trabalho cita equipamentos de iluminação, lâmpadas e luminárias com aplicação industrial disponíveis no mercado. Por fim, apresenta-se de um estudo de caso realizado em uma empresa do interior de São Paulo que possui pátios para estocagem de carvão em pó, analisando-se os resultados através de dados obtidos no local e da medição dos níveis de iluminância, efetuada em horários alternados. Tais dados foram comparados às normas e recomendações de boas práticas para concluir sobre a adequação da iluminação do galpão e alternativas para solução dos problemas encontrados foram propostas. A conclusão a que se chega é que é possível contribuir para uma melhora significativa nas instalações que provêm iluminação em galpões de minérios, padronizando-as, fazendo uma manutenção adequada, substituindo equipamentos obsoletos e observando-se as normas, visando o aumento de produtividade, segurança e conforto dos trabalhadores. Estas ações implicam ainda em economia e um menor consumo de energia, cooperando com a sustentabilidade ambiental e atendendo a requisitos da família das normas NBR ISSO 14.000. / Environmental questions, occupational health and safety management are each time, more recognized and required by civil society and public agencies in all levels. Some of the ore stores that are opened today will need in the future to be closed to comply with stronger environmental regulations, required by society through controlling environmental agencies. Those agencies require the stores to be air tight or to have an efficient system of dust and particulate airbone. One feasible possibility for this question is the storage of the ore in closed sheds, which demand a higher cost of implementation, but on the other hand, it has a low cost of operation. In closed stores, the lighting is very important, since it provides necessary conditions for the workers productivity, particularly in the case of a continuous twenty four hour working day. Also, in addition to safety management, there are questions which should be considered, namely, an adjusted illumination that stimulates productivity, throughout higher illuminance, higher contrast, less glare and at the same time is comfortable for the tasks that will be carried through that environment. In environments in which the particulate material is highly combustible, such as coal stores, an adequate and safety illumination is an elementary question and if badly designed, can cause fires, explosions and tragic disasters that can injure people and destroy the working area. This work was composed by reference to an extensive bibliographical revision. The first part is a review of lighting concepts; the second refers to health and safety matters, security in the work place and also reference to the lighting. The third part highlights the national and international rules for lighting and analyzes it\'s requests. The fourth part deal with hazardous areas and explosive atmospheres, and explains in simple terms what are classified areas, which are the criteria involved, the risks of common different types of dusts and related regulations. The fifth part explains about lighting of industrial stores, with related criteria used in an adequate lighting design standard. In the sixth part it outlines the selection of lighting fixtures, light bulbs and lighting ancillaries used for industrial applications available in the market. A case in a company in the state of São Paulo, that possesses storage facilities of coal dust was carried out. The results were analyzed through data collected throughout the store and the measurement of the illumination realized at different times of the day. Such data was compared to rules, regulations and best practices in order to decide on lighting adequacy of the store and alternatives to solve the encountered problems were proposed. The conclusion is that it is possible to contribute to a significant improvement in the installations that provide illumination in the ore stores by, standardizing them, providing adequate maintenance, substituting obsolete equipment and observing rules and regulations. These measures increases the productivity, security and comfort of the workers. This action also results in cost savings, less energy consumption and ensures cooperation with environmental sustainability and complies with the requirements of NBR ISO 14.000 series.
92

Development of a 1.8mm percutaneous applicator with closed cycle cooking for microwave tumour ablation

Wieland, Ines January 2009 (has links)
No description available.
93

Maximum Likelihood Identification of an Information Matrix Under Constraints in a Corresponding Graphical Model

Li, Nan 22 January 2017 (has links)
We address the problem of identifying the neighborhood structure of an undirected graph, whose nodes are labeled with the elements of a multivariate normal (MVN) random vector. A semi-definite program is given for estimating the information matrix under arbitrary constraints on its elements. More importantly, a closed-form expression is given for the maximum likelihood (ML) estimator of the information matrix, under the constraint that the information matrix has pre-specified elements in a given pattern (e.g., in a principal submatrix). The results apply to the identification of dependency labels in a graphical model with neighborhood constraints. This neighborhood structure excludes nodes which are conditionally independent of a given node and the graph is determined by the non- zero elements in the information matrix for the random vector. A cross-validation principle is given for determining whether the constrained information matrix returned from this procedure is an acceptable model for the information matrix, and as a consequence for the neighborhood structure of the Markov Random Field (MRF) that is identified with the MVN random vector.
94

A role for sensory areas in coordinating active sensing motions

Schroeder, Joseph Bradley 21 June 2016 (has links)
Active sensing, which incorporates closed-loop behavioral selection of information during sensory acquisition, is an important feature of many sensory modalities. We used the rodent whisker tactile system as a platform for studying the role cortical sensory areas play in coordinating active sensing motions. We examined head and whisker motions of freely moving mice performing a tactile search for a randomly located reward, and found that mice select from a diverse range of available active sensing strategies. In particular, mice selectively employed a strategy we term contact maintenance, where whisking is modulated to counteract head motion and sustain repeated contacts, but only when doing so is likely to be useful for obtaining reward. The context dependent selection of sensing strategies, along with the observation of whisker repositioning prior to head motion, suggests the possibility of higher level control, beyond simple reflexive mechanisms. In order to further investigate a possible role for primary somatosensory cortex (SI) in coordinating whisk-by-whisk motion, we delivered closed-loop optogenetic feedback to SI, time locked to whisker motions estimated through facial electromyography. We found that stimulation regularized whisking (increasing overall periodicity), and shifted whisking frequency, changes that emulate behaviors of rodents actively contacting objects. Importantly, we observed changes to whisk timing only for stimulation locked to whisker protractions, possibly encoding that natural contacts are more likely during forward motion of the whiskers. Simultaneous neural recordings from SI show cyclic changes in excitability, specifically that responses to excitatory stimulation locked to whisker retractions appeared suppressed in contrast to stimulation during protractions that resulted in changes to whisk timing. Both effects are evident within single whisks. These findings support a role for sensory cortex in guiding whisk-by-whisk motor outputs, but suggest a coupling that depends on behavioral context, occurring on multiple timescales. Elucidating a role for sensory cortex in motor outputs is important to understanding active sensing, and may further provide novel insights to guide the design of sensory neuroprostheses that exploit active sensing context.
95

The Open-Closed Cognitive Dimension and Divergent-Convergent Abilities

Uhes, Michael J. 01 May 1968 (has links)
The relationship between level of dogmatism and divergent-convergent abilities was investigated in a sample of high school subjects. Rokeach's Dogmatism Scale, Form E, and tests of divergent and convergent ability were administered to all subjects. On the basis of their performance on the Dogmatism Scale, three experimental groups were formed: high, medium , and low dogmatics. An analysis of the data showed dogmatism to be negatively correlated with originality, flexibility, composite divergent and composite convergent scores. Fluency was the only ability not negatively correlated with dogmatism. High dogmatic subjects performed convergent operations better than they performed divergent operations, while low dogmatic subjects performed both operations equally well.
96

Density-Dependent Convective Flow in Closed Basins

McCleary, Kim L. 01 May 1989 (has links)
The Great Basin is a region of the Basin and Range Physiographic Province, which is completely isolated hydrologically from the sea. All precipitation that falls within the Great Basin is lost from the land surface or from the surf ace of closed inland lakes through evapotranspiration. Playas are often found at the base of these undrained basins. This study focuses on subsurface groundwater flow patterns in closed basins. Because all discharge from the basins occurs via evapotranspiration on and near the playa, the water table of the aquifer beneath the playa is often just below the ground surface. Fluctuations of the water table due to climatic events cause the water table to rise and dissolve the salts on the playa surface. This mass transfer can produce density gradients that in turn cause flow. This study is an extension of the work performed by Duffy and Al-Hassan (Duffy and Al-Hassan 1988) in which numerical experiments were used to show that the free convection, caused by the variation in density of the bulk fluid propenies, appears to play an important role in determining the patterns of groundwater flow beneath the playa. Their work considered only homogeneous, isotropic porous media in symmetric basins. The effects of anisotropy, periodic stratification, and asymmetric basins on the groundwater flow and transport patterns was studied here. Dimensionless parameters, the Rayleigh number and the salt nose length, L0*, were defined for each of the systems incorporated and were shown to be linearly related. The implication of this relationship is that the Rayleigh number can be used to predict basin-scale circulation patterns in the hypothetical closed basins studied. It was also determined that an equivalent anisotropic system could be defined for a horizontally stratified aquifer in order to predict basin-scale circulation patterns. An equivalent isotropic system was defined for each anisotropic system in a similar manner.
97

Robotized Polishing and Deburring with Force Feedback Control

Krantz, Marthin, Andersson, Rikard January 2010 (has links)
<p>Force control is introduced to robots to solve the problem in machining applications due to the fact that the robot compliance might cause deviation between actual and desired robot path. Also large tolerances in the casting process as well as positioning errors from the clamping create deviations for which the force control technology can adept. Force control has also shown successful in automatic learning of paths along non linear surfaces.</p><p>This study investigates the possibility of introducing robots equipped with force control at Volvo Aero Corporation in order to robotize polishing and deburring processes. These are today performed by manual labor. This study investigates more specifically the ABB Force Control machining application package. The polishing process has shown to be very complex and today’s version of the ABB force control package cannot give sufficiently robust results to be recommended for implementation. The major issue is the non-existing compliance of tool orientation needed to adapt to casting and positioning deviations due to varying work piece dimensions. The deburring process has however shown to be easier to handle, and a robot cell and methodology is proposed in this report.</p>
98

Longitudinal impact of newly acquired closed-circuit televisions (CCTV) on quality of life for low vision patients

Huber, Jessica January 2007 (has links)
Ongoing efforts to quantify changes in quality of life attributable to low vision rehabilitation have focused on the utility of a single test instrument to measure this multidimensional concept. It is hypothesized that quality of life is best assessed using multiple instruments to capture some of its component facets, including functional status and psychosocial impact. Low vision devices have a predictably spontaneous impact on functional vision status, but associated psychosocial impact occurs with different magnitudes and over more protracted time intervals. The National Eye Institute Visual Function Questionnaire (NEI VFQ-25) measures the functional status of individuals in key vision areas that are associated with quality of life. The Psychosocial Impact of Assistive Devices Scale (PIADS) is an instrument that measures the psychosocial impact of assistive device intervention in three quality of life domains: competence, adaptability, and self-esteem. 68 participants were obtained from an ongoing parent study. These participants were recruited through the Low Vision Clinic at the University of Waterloo. They had a primary diagnosis of age-related macular degeneration (ARMD) and were obtaining a CCTV system for the first time. Assessments from the parent study used in this thesis included follow-up from 2 weeks, 1 month, 3 months, and 6 months post-adoption of the CCTV. The two tests administered were to measure functional vision status (NEI VFQ-25) and perceived psychosocial impact (PIADS), according the framework outlined by the Consortium for Assistive Technology Outcomes Research (CATOR). Multivariate repeated-measures ANVOA results confirmed that CCTV systems have an immediate and robust effect on the daily visual functioning of their users, and that this effect is stable over long periods of device use. The psychosocial impact of CCTV device use peaks in the shorter term and then seems to wane in the longer term for reasons that are not yet understood. The NEI VFQ-25 and the PIADS appear to have differential sensitivity to important influences on low vision rehabilitation outcomes. This project has demonstrated the value of longitudinal outcomes research in low vision rehabilitation. After obtaining a CCTV, visual function status remains static while psychosocial impact is dynamic during 6-months of follow-up.
99

Ruling Out David Miller's Argument for Immigration Restrictions

Delarosa, Yenipher 05 December 2011 (has links)
The paper will describe one of David Miller’s arguments for limiting immigration by concluding that immigration is a threat to a successful democratic welfare state. There is a threat to a democratic welfare state when there is lack of trust in a heterogeneous society. Immigration contributes to heterogeneity. The paper will present flaws in Miller’s argument, which include the unacknowledged concepts of ignorance and fear that can lead to mistrust in cultural heterogeneous communities. I will then consider Miller’s response to the critiques. Lastly, I will mention some proposals for increasing trust and addressing the real issues in a multicultural society.
100

Robotized Polishing and Deburring with Force Feedback Control

Krantz, Marthin, Andersson, Rikard January 2010 (has links)
Force control is introduced to robots to solve the problem in machining applications due to the fact that the robot compliance might cause deviation between actual and desired robot path. Also large tolerances in the casting process as well as positioning errors from the clamping create deviations for which the force control technology can adept. Force control has also shown successful in automatic learning of paths along non linear surfaces. This study investigates the possibility of introducing robots equipped with force control at Volvo Aero Corporation in order to robotize polishing and deburring processes. These are today performed by manual labor. This study investigates more specifically the ABB Force Control machining application package. The polishing process has shown to be very complex and today’s version of the ABB force control package cannot give sufficiently robust results to be recommended for implementation. The major issue is the non-existing compliance of tool orientation needed to adapt to casting and positioning deviations due to varying work piece dimensions. The deburring process has however shown to be easier to handle, and a robot cell and methodology is proposed in this report.

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