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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.
11

Qualidade fÃsica de um Luvissolo cultivado com sistemas agroflorestais e convencional no semi-Ãrido cearense / Quality physical of the Luvissolo in the semi-arid of Cearà in agroforestry systems and intensive cropping

Giovana Lopes da Silva 30 May 2008 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A introduÃÃo de sistemas agrÃcolas no ecossistema natural altera o equilÃbrio do solo, com reflexos na sua qualidade, cujos impactos dependerÃo do tipo de manejo utilizado e da capacidade de suporte do solo. Uma das alternativas à a adoÃÃo dos sistemas agroflorestais, pois tais sistemas promovem a proteÃÃo do solo e sÃo capazes de manter a sua qualidade em condiÃÃes semelhantes a do solo sob vegetaÃÃo natural, jà que as Ãrvores favorecem as propriedades fÃsicas do solo. Assim foi desenvolvido um estudo com o objetivo de avaliar a qualidade fÃsica e estrutural em um Luvissolo no semi-Ãrido cearense cultivado com sistemas de manejo agroflorestal (SAFs) e convencional, utilizando o Intervalo HÃdrico Ãtimo (IHO) e o Ãndice S. A Ãrea em estudo localiza-se na Fazenda Crioula em Sobral â CE, pertencente à EMBRAPA â CNPC. Os tratamentos selecionados, para tal estudo foram: Agrissilvipastoril (AGP), Silvipastoril (SILV), VegetaÃÃo Natural (VN) e Cultivo Intensivo em Pousio (CIP). As amostras foram submetidas a um gradiente de tensÃo de Ãgua sendo posteriormente utilizadas nas determinaÃÃes de densidade do solo (Ds), resistÃncia à penetraÃÃo de raÃzes (RP) e umidade volumÃtrica (θ). Em seguida, os resultados foram utilizados para os ajustes das curvas de retenÃÃo de Ãgua (CRA) e de resistÃncia à penetraÃÃo (CRP). AtravÃs da CRA e da CRP, foi possÃvel quantificar o IHO e a densidade do solo crÃtica (Dsc). Determinou-se tambÃm os valores dos parÃmetros da equaÃÃo de van Genuchten, para determinaÃÃo do Ãndice S. Os SAFs apresentaram melhores condiÃÃes fÃsicas e estruturais para o crescimento das plantas, tanto pela avaliaÃÃo do IHO, como pelo Ãndice S. O CIP, apresentou o menor IHO e o menor valor de S, indicando uma maior degradaÃÃo fÃsica e estrutural para o solo deste tratamento. / The introduction of agricultural systems in the natural ecosystem changes the balance of the soil, with reflections on their quality, whose impact will depend on the type of management used and the capacity to support the ground. One of the alternatives is the adoption of agroforestry systems, because these systems promote the protection of soil and are able to maintain their quality under similar conditions, the soil under natural vegetation, since the trees, encourage the soil physical properties. So a study was carried out to evaluate the quality of physical and structural Luvissolo in the semi-arid of Cearà cultivated with agroforestry systems (SAFs) and conventional, using the Least Limiting Water Range (LLWR) and the Index S. The area under study is located on the farm in Crioula Sobral - CE and belongs to the EMBRAPA - CNPC. The treatments selected for this study were: Agrosilvipasture (AGP), Silvipasture (SILV), Natural Vegetation (VN) and Intensive Cropping (CIP). The samples were subjected to a voltage gradient of water and then used in determination of soil density (Ds), resistance to penetration of roots (RP) and volumetric moisture (θv). Then, the results were used for the adjustment of the retention curve of water (CRA), and resistance to penetration (CRP). Through the CRA and the CRP, it was possible to quantify the LLWR and soil critic density (Dsc). There is also the determinate the values of the van Genuchten parameters, for determining the index S. The SAFs showed better physical and structural conditions for plants growth, both for the evaluation of the IHO, and the index S. The CIP, presented the lowest IHO and the lowest value of S, indicating greater physical and structural degradation to soil this treatment.
12

Dubysos upės vidurupio vandens kokybės vertinimas bioindikacijos metodais / Middle of the river Dubysa water quality assessment by the methods of bioindication

Keblaitė, Živilė 20 June 2012 (has links)
Šio darbo tikslas – įvertinti Dubysos upės vidurupio vandens kokybę, taikant bioindikacinius vandens telkinių vertinimo metodus. Naudojant Saprobiškumo (S) ir Simpsono įvairovės indeksų (D) metodus buvo identifikuoti zooplanktoniniai organizmai bei įvertinti rūšių skaičiaus, gausumo ir įvairovės pasiskirstymo dėsningumai. Pagal J. Brown-Blanquet skalę atliktas atskirų augalų rūšių gausumo (projekcinis padengimo) barelyje vertinamas. Apie 50 km atkarpoje buvo išdėstytos 15 tyrimų vietų, kurias pasirenkant buvo atsižvelgiama į netoliese esančius žemės ūkio, pramonės, transporto objektus bei gamtinę aplinką. Tiriant zooplanktoniną paimti 270 vandens ir vandens – dumblo mėginiai. Šie tyrimai atlikti tris kartus metuose, bandymą pakartojant tris kartus. Naudojant J. Brown-Blanquet skalę augalų projekcinio padengimo vertinimas atliktas liepos mėn. Taigi vandens kokybės vertinimui buvo skaičiuoti tokie rodikliai: zooplanktoninių organizmų rūšių skaičius, gausumas, Simpsono įvairovės (D), Saprobiškumo (S) indeksai bei augalų projekcinis padengimas. Tirtoje teritorijoje buvo aptikta 33 zooplanktono rūšys: 8 infuzorijos, 8 dumbliai, 2 bakterijos, 2 vabzdžių lervos, 3 verpetės, 4 pirmuonys, 2 šakotaūsiai ir 3 irklakojai vėžiagyviai. Taikyta vienfaktorinė dispersinė analizė (One–way ANOVA) parodė, kad tyrimų vietos vandens kokybė (vandens užterštumas arba švarumas) turi įtakos vandens kokybę indikuojantiems rodikliams (rūšių skaičiui, gausumui, D bei S indeksams). Rūšių sudėtis ir... [toliau žr. visą tekstą] / The aim – to assess middle of the river Dubysa water quality, using valuation techniques by bioindicationous water mines. Using saprobic index (S) and Simpson's diversity index (D) methods have been identified zooplanktons organisms and the number of species, abundance and diversity of distribution patterns. According to J. Brown-Blanquet scale of an individual plant species richness (covering projection) rating in the barrel. About 50 km stretch was down 15 test sites, the choice was taken to the nearby agricultural, industrial, transport facilities and the environment. Studying zooplankton, it was taken of 270 water mines, and water - sludge ("hanging drop") samples. These studies were conducted three times a year, repeating the test three times. Using J. Brown-Blanquet scale projection covering the plant assessment was carried out in July. Thus, the assessment of water quality indicators have been calculated as follows: organisms zooplankton number of species, abundance, Simpson's diversity index (D), saprobic index (S) and the projection coating plant. There was found 33 species of investigated zooplankton area: 8 infusoria, 8 algae, 2 bacteria, 2 insect larvae, 3 vortex, 4 protozoa, crustaceans 2 and 3 copepods. Applied to one factor analysis of variance (one-way ANOVA) revealed that research on local water quality (water pollution or purity) affect water quality for indication indicators (number of species, abundance, D index). Species composition and quantitative... [to full text]
13

Analýza výnosnosti a rizika vybraného odvětví burzy cenných papírů / Return and risk analysis in the selected industries

VELEBOVÁ, Anna January 2015 (has links)
This thesis deals with the analysis of the profitability and risk of selected sectors on a stock exchange. For analysis of the industry period of 5 years was selected. This period begins in January 2010 and ends in December 2014. Data for the analysis were obtained from the New York Stock Exchange. Ratings industry is based on key indicators of profitability and risk. The profitability of the sector was calculated average and total. The risk was assessed by standard deviation, variance and coefficient of variation. The next step was to evaluate the sector by pricing model of capital asset. The coefficients alpha and beta were obtained by linear regression. MS Excel software was used for calculation. The first part describes the capital market, its subjects and the stock exchanges. For assessing the shares the basic formulas for calculating profitability, risk and CAPM are described in the theoretical part. Methodology paper describes the procedure for evaluating stocks and sectors. There is described a precise procedure of calculating individual indicators. In the third section the results of the analyzed sectors are evaluated. There is described the risk assessment of the industry and the future development of the sector. In conclusion the capital market and forecast of its development are evaluated.
14

Využití prostředků umělé inteligence na kapitálových trzích / The Use of Means of Artificial Intelligence for the Decision Making Support on Stock Market

Vaško, Jan January 2011 (has links)
Diploma thesis deals with analyzing the possibility of using artificial intelligence, specifically artificial neural networks and fuzzy logic, on the capital markets as a tool to support decision making in business. The Matlab software is used for this purpose. The work is divided into three parts. The first part deals with theoretical knowledge, brief description of the current situationin is covered in a second part and the theoretical solutions are applied to the system in the third section.
15

Využití prostředků umělé inteligence pro podporu na kapitálových trzích / The Use of Means of Artificial Intelligence for the Decision Making Support on Stock Market

Ševčík, Martin January 2012 (has links)
This diploma thesis describes issues of use of means of artificial intelligence for the decision making support on stock market. It includes theoretical knowledge of technical, fundamental and psychological analysis and artificial intelligence. Based on these facts have been created specific suggestions for the use of artificial neural networks to forecast the future value of the index S&P 500 by using development environment of the MATLAB software.

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