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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.
31

Software Design Conflicts : Maintainability versus Performance and Availability

Häggander, Daniel January 2001 (has links)
A major goal in software engineering is to reduce the cost of maintaining software systems. Finding design methods which make software more easily maintainable has thus been one of the most prioritized challenges during the past decade. While mainstream software design has concentrated on maintainability, other software disciplines e.g. high-performance computing and high-availability systems, have developed other design methods which primarily support the quality attributes that are more important in their areas. More recently, demands have been made for high performance and high availability in typical mainstream software. At the same time, traditional high-performance and high-availability systems tend to incorporate more advanced business functionality, i.e. different software disciplines have started to converge. The situation is not unproblematic since the software design methods developed for achieving performance and availability may have been developed with a limited influence from maintainability, and vice versa. It is thus important to identify and analyze emerging design conflicts. In this thesis I have studied conflicts between maintainability design methods onthe one hand, and performance and availability methods and techniques on the other. I present the results of four case-studies involving four different applications. It is a characteristic of these applications that half of the system can be regarded as a telecommunications system and the other as a typical main-stream system, i.e. all systems make high demands on performance and availability but also very high demands on high maintainability. In studying these applications, I have identified two major conflicts: granularity in dynamic memory usage and source code size. My results show that these two conflicts can cause problems of such amplitude that some applications become unusable. I found that conflicts in certain situations are inherent; in other cases they can be avoided - or at least reduced - by adjusting the design methods used. I have also shown that conflicts may quite simply be a matter of misconceptions. Ten guidelines have been combined into a simple process with the aim of helping software designers to avoid and reduce conflicts. A method which automatically reduces the dynamic memory conflict in object-oriented applications written in C++ has been developed, implemented and evaluated. Finally, I have defined optimal recovery schemes for high availability clusters.
32

Nocturnal bird migration and disrupted sleep/wake cycle

Singletary, Kristan Gail 23 October 2009 (has links)
In most birds, changing photoperiods from winter to spring and from summer to fall have two consequences: increased feeding followed by migratory activity. To date, the neural system controlling the activation of migratory activity remains unknown, though behavioral observations point to a possible mechanism. During the migration season, diurnal songbirds show extensive disruption of their sleep/wake cycle, sleeping during the day and flying at night. In mammals, similarly altered cycles of activity result from blocking orexin expression in the hypothalamus. It is possible that decreased orexin expression is associated with migratory activity in songbirds. In addition, changes in ingestive behaviors and fuel availability may also be associated with disruptions in the sleep/wake cycles of migratory birds. The studies in my dissertation will address these issues through three main specific aims. First, I will determine that orexin systems are conserved in vertebrate brains. Second, I will test the association between orexin and migratory activity in songbirds. Third, I will confirm the association between fuel availability, orexin expression and migratory activity in songbirds. / text
33

Disponibilidade de metais em amostras de fosfogesso e fertilizantes fosfatados utilizados na agricultura / Availability of metals in samples of phosphogypsum and phosphate fertilizers used in agriculture

Bourlegat, Fernanda Melo Le 18 August 2010 (has links)
Os fertilizantes fosfatados produzidos no Brasil são obtidos principalmente pelo processamento por via úmida da rocha fosfática ígnea com ácido sulfúrico concentrado, gerando como produto final o ácido fosfórico e como subproduto o sulfato de cálcio di-hidratado (fosfogesso ou gesso agrícola). Parte do fosfogesso gerado é estocada em pilhas a céu aberto e parte vem sendo utilizada na agricultura como condicionador de solos. Para garantir utilização segura do fosfogesso na agricultura é importante a determinação dos teores de impurezas, em particular os metais, presentes no mesmo. Neste trabalho foram determinadas as concentrações dos metais (As, Ba, Cd, Cr, Co, Cu, Hg, Ni, Pb, Se, Zn e elementos terras raras - ETR) presentes no fosfogesso (FG) e nos fertilizantes superfosfato simples (SSP), superfosfato triplo (TSP), fosfato monoamônio (MAP) e o di-amôniofosfato (DAP) produzidos no Brasil. Os metais Cd, Cu, Ni, Pb e Zn foram determinados de acordo com a metodologia EPA 3052. Os mesmos metais, As e Se também foram determinados de acordo a metodologia EPA 3050B, recomendada pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA). Todos estes metais possuem limites máximos de concentração estabelecidos pelo órgão de meio ambiente estadual, Companhia Ambiental do Estado de São Paulo (CETESB), e/ou pelo MAPA. As duas metodologias apresentaram valores de concentração diferentes para os metais analisados. Ba, Co, Cr e ETR foram determinados pela técnica de análise por ativação neutrônica instrumental (INAA). Avaliou-se também a disponibilidade dos metais As, Cd, Cr, Co, Cu, Ni, Pb, Se e Zn para o meio ambiente determinando-se a concentração destes por meio de metodologia estabelecida pela Comunidade Européia. Todos os resultados obtidos para as amostras de fosfogesso estão abaixo dos limites estabelecidos pelo MAPA e pela CETESB. As concentrações dos metais presentes no fosfogesso são menores do que os valores encontrados nos fertilizantes fosfatados estudados. Esta última metodologia mostrou que os metais presentes nas amostras estão muito pouco disponíveis para o meio ambiente. Os resultados atestam a aplicação segura deste subproduto nos solos agrícolas quanto ao quesito de contaminação por metais. / The Brazilian phosphate fertilizer is obtained by wet reaction of the igneous phosphate rock with concentrated sulphuric acid, giving as final product, phosphoric acid, and dehydrated calcium sulphate (phosphogypsum) as by-product. Part of this phosphogypsum is stored in stacks at open air and part has been used in agriculture, as soil amendment. To assure a safe utilization of phosphogypsum it is important to determine the levels of impurities, particularly of metals, present in phosphogypsum. In this paper, the concentration of metals (As, Ba, Cd, Cr, Co, Cu, Hg, Ni, Pb, Se, Zn and rare earth elements) present in Brazilian phosphogypsum and also in single super phosphate (SSP), triple super phosphate (TSP), monoammonium phosphate (MAP) and diammonium phosphate (DAP) were determined. The metals Cd, Cu, Ni, Pb and Zn were determined following the procedure EPA 3052. The same elements, As and Se were also determined following the procedure EPA 3050B, recommended by Ministério da Agricultura, Pecuária e Abastecimento (MAPA). All these metals are controlled by environmental and agriculture regulation institutes in Brazil. The concentrations obtained for the metals analyzed by using the two procedures were different. Ba, Co, Cr and rare earth elements were determined by neutron activation analysis. In order to evaluate the availability of these metals As, Cd, Cr, Co, Cu, Ni, Pb, Se and Zn to the environment, the content of the same elements were determined following a procedure established by the EC (European Community), which includes an initial attack of the samples with EDTA-NH4 0.05M, at pH 7.0. In all these cases, phosphogypsum presented metals concentration lower than the phosphate fertilizers, and the results are below the limits adopted by MAPA and Companhia Ambiental do Estado de São Paulo (CETESB). The results obtained using the methodology with mild attack show that the metals are not available to the environment, giving evidence that the application of phosphogypsum in agriculture is safe as far as contamination by metals.
34

Zajištění dostupnosti IT infrastruktury pro podporu firemních procesů

Zima, Radek January 2005 (has links)
Cílem práce je podat ucelený přehled o aktuálních technologiích sloužících k zajištění dostupnosti IT infrastruktury v podniku. Autor má zkušenosti nejen s konkrétními technologiemi a přístupy k zajištění vyšší odolnosti jednotlivých komponent serveru vůči výpadku (ukládání dat, napájení, řízení toku vzduchu, ochrana paměti, ?) , ale i se softwarovými produkty, které zajistí redundanci celého serveru. Tento přístup byl otestován i v případové studii, kde proběhla analýza stávající situace ve vybrané společnosti a nalezeny funkce poskytované jednotlivými komponentami infrastruktury. Kromě detailního zmapování situace byla nalezena i slabá místa a doporučeno řešení.
35

Disponibilidade de metais em amostras de fosfogesso e fertilizantes fosfatados utilizados na agricultura / Availability of metals in samples of phosphogypsum and phosphate fertilizers used in agriculture

Fernanda Melo Le Bourlegat 18 August 2010 (has links)
Os fertilizantes fosfatados produzidos no Brasil são obtidos principalmente pelo processamento por via úmida da rocha fosfática ígnea com ácido sulfúrico concentrado, gerando como produto final o ácido fosfórico e como subproduto o sulfato de cálcio di-hidratado (fosfogesso ou gesso agrícola). Parte do fosfogesso gerado é estocada em pilhas a céu aberto e parte vem sendo utilizada na agricultura como condicionador de solos. Para garantir utilização segura do fosfogesso na agricultura é importante a determinação dos teores de impurezas, em particular os metais, presentes no mesmo. Neste trabalho foram determinadas as concentrações dos metais (As, Ba, Cd, Cr, Co, Cu, Hg, Ni, Pb, Se, Zn e elementos terras raras - ETR) presentes no fosfogesso (FG) e nos fertilizantes superfosfato simples (SSP), superfosfato triplo (TSP), fosfato monoamônio (MAP) e o di-amôniofosfato (DAP) produzidos no Brasil. Os metais Cd, Cu, Ni, Pb e Zn foram determinados de acordo com a metodologia EPA 3052. Os mesmos metais, As e Se também foram determinados de acordo a metodologia EPA 3050B, recomendada pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA). Todos estes metais possuem limites máximos de concentração estabelecidos pelo órgão de meio ambiente estadual, Companhia Ambiental do Estado de São Paulo (CETESB), e/ou pelo MAPA. As duas metodologias apresentaram valores de concentração diferentes para os metais analisados. Ba, Co, Cr e ETR foram determinados pela técnica de análise por ativação neutrônica instrumental (INAA). Avaliou-se também a disponibilidade dos metais As, Cd, Cr, Co, Cu, Ni, Pb, Se e Zn para o meio ambiente determinando-se a concentração destes por meio de metodologia estabelecida pela Comunidade Européia. Todos os resultados obtidos para as amostras de fosfogesso estão abaixo dos limites estabelecidos pelo MAPA e pela CETESB. As concentrações dos metais presentes no fosfogesso são menores do que os valores encontrados nos fertilizantes fosfatados estudados. Esta última metodologia mostrou que os metais presentes nas amostras estão muito pouco disponíveis para o meio ambiente. Os resultados atestam a aplicação segura deste subproduto nos solos agrícolas quanto ao quesito de contaminação por metais. / The Brazilian phosphate fertilizer is obtained by wet reaction of the igneous phosphate rock with concentrated sulphuric acid, giving as final product, phosphoric acid, and dehydrated calcium sulphate (phosphogypsum) as by-product. Part of this phosphogypsum is stored in stacks at open air and part has been used in agriculture, as soil amendment. To assure a safe utilization of phosphogypsum it is important to determine the levels of impurities, particularly of metals, present in phosphogypsum. In this paper, the concentration of metals (As, Ba, Cd, Cr, Co, Cu, Hg, Ni, Pb, Se, Zn and rare earth elements) present in Brazilian phosphogypsum and also in single super phosphate (SSP), triple super phosphate (TSP), monoammonium phosphate (MAP) and diammonium phosphate (DAP) were determined. The metals Cd, Cu, Ni, Pb and Zn were determined following the procedure EPA 3052. The same elements, As and Se were also determined following the procedure EPA 3050B, recommended by Ministério da Agricultura, Pecuária e Abastecimento (MAPA). All these metals are controlled by environmental and agriculture regulation institutes in Brazil. The concentrations obtained for the metals analyzed by using the two procedures were different. Ba, Co, Cr and rare earth elements were determined by neutron activation analysis. In order to evaluate the availability of these metals As, Cd, Cr, Co, Cu, Ni, Pb, Se and Zn to the environment, the content of the same elements were determined following a procedure established by the EC (European Community), which includes an initial attack of the samples with EDTA-NH4 0.05M, at pH 7.0. In all these cases, phosphogypsum presented metals concentration lower than the phosphate fertilizers, and the results are below the limits adopted by MAPA and Companhia Ambiental do Estado de São Paulo (CETESB). The results obtained using the methodology with mild attack show that the metals are not available to the environment, giving evidence that the application of phosphogypsum in agriculture is safe as far as contamination by metals.
36

Availability and Perceived Adequacy of Health Services in Utah

Thayer, Cheryl L. 01 May 1976 (has links)
It is the general consensus that continuous and comprehensive health care of good quality should be available to all, under conditions that are convenient, comfortable, and not detrimental to the dignity or self-respect of the individual. This study concerns the adequacy of health services as perceived by persons living in rural, urban, and urbanizing-rural areas of Utah. It is also a study (1) to determine the degree to which various demographics found to be related to differential medical needs in metropolitan areas is related to perception of health services, and (2) to assess the congruence between empirical and perceived availability of health services among persons of varying age, sex, education, and other conditions generally related to the use of health services. The findings on perceived availability tend to more closely reflect the actual availability of health services than demographic background differences between urban and rural areas. The urbanizing-rural areas, however, do not reflect the actual availability of health services, as much as they do the improvement in availability of health services. Within both rural and urban areas and to a lesser degree within urbanizing-rural areas, health service delivery as perceived by different categories of the population appears to be quite equitable.
37

Role of Different Carbon Sources for Growth, Production and Community Composition of Bacterioplankton

Lindh, Markus January 2008 (has links)
<p>It has been suggested that growth, production and community structure of bacterioplankton are dependent on resource availability. However, previous studies have only investigated the effect of either organic substrate mixtures or a few single organic substrates on the bacterioplankton community. The aims of this study were to investigate the impact of five different relevant carbon sources on the bacterioplankton community. This impact was evaluated comparing treatments on samples taken from Skagerrak and the Baltic Sea, in whole seawater cultures. Analysis of bacterial abundance, bacterial production (as leucine incorporation), bacterioplankton DNA community structure and colony-forming bacteria growing on agar plates were evaluated. Differences between carbon sources in terms of bacterial numbers were relatively small, with strong growth responses for L-amino acids, glucose, acetate and pyruvate with the only exception of glycolate where growth was lower. Bacterial production, on the other hand, presented marked differences, different patterns for each carbon source, especially in the Baltic Seawater. Furthermore, differences in colony size and number of colony forming bacteria in the different treatments were important. The analysis of DNA community from each experiment, by denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rDNA, allowed a visualization of the microbial community structure. Sequencing of the stronger bands on the gel revealed the identity of the dominant bacterial species. In terms of bacterioplankton community structure, differences between carbon sources and between environments were important. One unknown species belonging to gamma-proteobacteria was both unique and dominant for glucose treatment in the Baltic experiment. Another gamma-proteobacteria , a Vibrio was found to specialize in glucose in the Skagerrak experiment. One uncultured bacterium belonging to a alpha-proteobacteria, both unique and dominant was found in glycolate, also this in Skagerrak, another uncultured alpha-proteobacteria was clearly dominant for glucose treatment in Skagerrak. Some bands were also present in most treatments, e.g. uncultured species belonging to bacteroidetes in Skagerrak and beta-proteobacteria in Baltic, suggesting that those species are not specialized in consuming a single carbon source. As a conclusion different carbon sources clearly had an individual but important role for bacterioplankton properties. The properties also showed to be dependent on the environment.</p><p>Nr:6355</p>
38

A DHT-Based Grid Resource Indexing and Discovery Scheme

Teo, Yong Meng, March, Verdi, Wang, Xianbing 01 1900 (has links)
This paper presents a DHT-based grid resource indexing and discovery (DGRID) approach. With DGRID, resource-information data is stored on its own administrative domain and each domain, represented by an index server, is virtualized to several nodes (virtual servers) subjected to the number of resource types it has. Then, all nodes are arranged as a structured overlay network or distributed hash table (DHT). Comparing to existing grid resource indexing and discovery schemes, the benefits of DGRID include improving the security of domains, increasing the availability of data, and eliminating stale data. / Singapore-MIT Alliance (SMA)
39

Comparison of the efficiency of a thermo-chemical process to that of a fuel cell process when both involve the same chemical reaction

Bulusu, Seshu Periah 15 May 2009 (has links)
This work assesses if a plausible theoretical thermo-chemical scheme can be conceived of, that is capable of extracting work from chemical reactants which can be compared with work produced by a fuel cell, when both processes are supplied with the same reactants. A theoretical process is developed to convert heat liberated from a chemical reaction to work. The hypothetical process is carried over a series of isothermal chemical reactor - heat engine combinations. Conducting the chemical reaction and work extraction over a series of temperature steps minimizes irreversibilities that result from the chemical reaction and heat transfer. Results obtained from the numerical calculations on the scheme confirm that when a large number of reactors-engine combinations are used, irreversibility of the proposed hypothetical reactor-engine combination can be reduced to zero. It is concluded from the results, that the theoretical model is as efficient as a fuel cell when both have the same chemical reaction under identical conditions. The effect of inert gas chemistry on the process has also been observed. It is determined from the results that the chemistry of the inert gas does not affect the proposed process. It is determined from results of a parametric study on the composition of inert gas, that the reduction of inert gas does not significantly improve the efficiency of the proposed process.
40

Improving availability awareness with relationship filtering

Davis, Scott M. 06 January 2006
Awareness servers provide information about a person to help observers determine whether a person is available for contact. A trade -off exists in these systems: more sources of information, and higher fidelity in those sources, can improve peoples decisions, but each increase in information reduces privacy. In this thesis, we look at whether the type of relationship between the observer and the person being observed can be used to manage this trade-off. We conducted a survey that asked people what amount of information from different sources that they would disclose to seven different relationship types. We found that in more than half of the cases, people would give different amounts of information to different relationships. We then constructed a prototype system and conducted a Wizard of Oz experiment where we took the system into the real world and observed individuals using it. Our results suggest that awareness servers can be improved by allowing finer-grained control than what is currently available.

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