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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.
61

Effets des contraintes mécaniques du sol sur la limitation des rendements du tournesol / Impact of soil mechanical constraints on sunflower yield limitation

Mirleau-Thebaud, Virginie 09 May 2012 (has links)
La production de tournesol inclue des interactions complexes entre le génotype et l'environnement tout au long du cycle de la culture. La profondeur de l'enracinement du tournesol est fortement liée au sol, à sa structure et à la disponibilité en eau. La compaction du sol représente un enjeu important dans le contexte actuel de la durabilité des systèmes agricoles, et se caractérise par une diminution de la disponibilité hydrique du sol, une augmentation de la densité apparente et la résistance du sol à la pénétration. L’altération de l'exploration du système racinaire et de ses conséquences sur la croissance du système aérien sous contraintes mécaniques du sol a été explorée pour de nombreuses cultures (maïs Zea mays, Blé Triticum durum, ou de soja Glycine max). Peut d’études ont été réalisée sur le tournesol (Helianthus annuus L.). Parmi ces études seules quelqu’une incluent des cinétiques de croissance, encore moins incluent la qualité de la production. Le but de ce travail est d'étudier i) les modifications du système racinaire causée par la compaction du sol, ii) l'altération du système aérien causé par la modification du système racinaire, et iii) les interactions entre les systèmes. Une synthèse réalisée à partir la littérature et du schéma conceptuel du modèle STICS a permis d’établir un schéma conceptuel théorique retraçant le mécanisme des actions de la compaction du sol sur la plante de tournesol. A partir de ce schéma, deux expérimentations au champ et une expérience en conditions contrôlées ont été construites. En présence de compaction du sol, une diminution de la disponibilité hydrique, une augmentation de la densité apparente et la résistance du sol à la pénétration ont été observées conformément à la littérature. Le stress causé par la contrainte mécanique du sol a induit une réduction de la croissance et de l'exploration du système racinaire. Ceci a engendré une diminution de la surface foliaire, de la biomasse aérienne, et de la hauteur des plantes. Les pertes d'efficacité de l'utilisation des ressources et de rendement ont été observées par des indicateurs indirects. Les analyses de sensibilité de STICS ont été effectuées sur les paramètres d'intérêts, confirmant le seuil à partir duquel la compaction du sol conduit à des effets négatifs sur la plante de tournesol. Des propositions ont été faites pour adapter le modèle à la croissance du système racinaire de tournesol, i) en établissant une liaison directe entre les appareils aérien et souterrain, et ii) en réajustant l'indice de stress provoqué par les variations de densité apparente / The sunflower production takes place throughout complex interactions between the genotype, the crop management and the environment. Sunflower rooting depth is strongly related with soil structural behavior and gravimetric water availability. Soil compaction represents an important issue in the actual context of agricultural system durability, and is characterized by a decrease of soil available water, an increase of bulk density and soil resistance to the penetration. Variation of root system exploration and their consequences on above ground growth and development under soil mechanical constraints have been explored for many crops (Maize Zea mays, Wheat Triticum durum, or Soybean Glycine max), but only few researches have been carried out on sunflower (Helianthus annuus L.). Among them only few includes kinetic aspects and less quality of production. The aim of this work is to study i) the root system modifications caused by soil compaction, ii) the above ground system alteration caused by root system modification, and iii) the interactions between the systems. An analysis carried out from literature and the model STICS conceptual framework lead to the construction of a conceptual framework explaining the mechanism of soil compaction actions on sunflower plant. From this knowledge, two field experiments and a controlled experiment were built. In presence of soil compaction a decrease of soil water availability and an increase of bulk density and soil resistance to penetration were observed as reported in literature. The stress caused by soil mechanical constraint induced a reduction of root system growth and exploration. This induced a decrease of leaf area, shoot biomass, and plant height. The use efficiency of resource and yield lost were observed by indirect indicators. Sensitivity analyses of STICS were done on parameter of interest, confirming the threshold above which soil compaction lead to negative impact on sunflower. Proposition were made to adapt the model to sunflower root system growth, by implementing a direct link between shoot and root growth, and by readjusting the bulk density stress index
62

Geological factors affecting the channel type of Bjur River in Västerbotten County : A study concerning the connection between surficial geology, landforms, slope and different hydrological process domains in a stream catchment above the highest shoreline

Skog, Emma January 2019 (has links)
Process domains categorizes sections of streams according to its local dominant processes. These processes often reflect on the local ecology and the streams appearance. But the underlying reason why these different process domains are formed are still not completely certain. In this study the distribution of the process domains: lakes, rapids and slow-flowing reaches in the Bjur River catchment were compared to the geological factors of slope, surficial geology and landforms to see if any connections could be found. The possibility of using GIS (geographic information systems) and remote data to distinguish these stream types and to connect them to the different studied geological factors were also examined. The hypothesis for this study is that the geological factors of slope, surficial geology and landforms all should have an influence over the distribution of the process domains in Bjur River. The analysis was executed through map-studies in ArcGIS and statistical analysis in Excel. All process domains showed statistical significance towards the studied geological factors. The slope was generally steeper in the rapids than in slow-flowing reaches and lakes. The surficial geology displayed more fine-grained sediment (peat) in proximity to lakes and slow-flowing reaches whilst till was more abundant close to rapids. Hilly moraine landscapes were most common around lakes, while rapids displayed a high percentage of glacio-fluvially eroded area. Slow-flowing reaches also showed to have around 44% of its studied points around glacio-fluvially eroded area, and 43% at areas without any major landforms. Even if the statistical analysis and figures display a difference between the different process domains, it is still difficult to say which of these geological factors that plays the most crucial role for their development. However, by using remote data and through studies over slope, adjacent surficial geology and landforms the different process domains can be differentiated from one another.
63

Variabilidade espacial nos estoques de carbono em paisagens fragmentadas da Mata Atlântica / Spatial variability in carbon stocks in the Atlantic Forest fragmented landscapes

Romitelli, Isabella 04 July 2014 (has links)
O desmatamento e a fragmentação decorrentes da expansão das atividades humanas nas paisagens florestais tropicais promovem mudanças na estrutura da paisagem, em geral com perda de florestas antigas para a agricultura ou pastagem, parcialmente compensada regionalmente com a regeneração das florestas secundárias jovens. Tal processo gera paisagens heterogêneas, com florestas secundárias em diferentes estádios de sucessão e perturbação. O estoque de carbono nestas florestas pode, assim, variar muito e essa variação pode ocorrer em diferentes escalas espaciais. O presente estudo buscou entender como as diferentes condições locais e da paisagem contribuem para o estoque de carbono. O estudo foi realizado em florestas secundárias da Mata Atlântica, no Sistema Cantareira (região sudeste do Brasil). A biomassa acima do solo (BAS) foi estimada a partir de dados de inventário florestal e modelos alométricos de biomassa. A fim de testar como a biomassa de uma floresta tropical varia em paisagens antropizadas, foram construídos modelos lineares generalizados (GLM, distribuição Gaussiana) com quatro grupos de variáveis: idade da floresta; perturbações humanas; topografia (declividade e altitude); e estrutura da paisagem. Foram construídos modelos simples, compostos, com e sem interação, além do modelo nulo. O modelo mais plausível foi selecionado pelo critério de Akaike corrigido para pequenas amostras (AICc). Numa escala mais local, a variação da BAS em função da distância à borda foi analisada. A BAS variou amplamente entre os locais de estudo e isso foi parcialmente explicado pelas variáveis explanatórias, uma vez que todos os modelos e variáveis selecionadas foram melhores do que os modelos nulos. O resultado mais surpreendente foi o baixo estoque geral de carbono nas áreas de estudo (30,91 ± 11,00 Mg.ha-1). Os resultados sugerem que este padrão está principalmente relacionado com efeitos de borda e com a influência de fatores diretamente impulsionados pela ocupação humana (como, por exemplo, florestas mais perturbadas, paisagens com baixa cobertura florestal e ocorrência relativa alta de florestas mais jovens). Os resultados indicam ainda que nesta condição de alta perturbação os fatores abióticos, tais como a localização topográfica, podem ter uma importância menor do que seria de esperar por estudos anteriores. Os baixos estoques de carbono e alta variabilidade espacial observada indicam a necessidade de se incorporar estimativas de carbono em escalas espaciais mais finas em programas de mitigação climática e de manutenção de serviços ecossistêmicos em paisagens fragmentadas / Deforestation and fragmentation resulting from the expansion of human activities in tropical forest landscapes promote changes in landscape structure, usually with loss of mature forests for agriculture or pasture, partially offset regionally with the regeneration of young secondary forests. This process generates heterogeneous landscapes with secondary forests in different stages of succession and disturbance. The stock of carbon in these forests can thus vary greatly and this variation may occur at different spatial scales. This study aimed to understand how the different local and landscape conditions contribute to carbon stock. The study was performed in secondary Atlantic Forest fragments in Cantareira System (southeastern Brazil). The above-ground biomass (AGB) was estimated by forest inventory data and allometric biomass models. In order to test how the biomass of a tropical forest varies in disturbed landscapes, generalized linear models (GLM, Gaussian distribution) were constructed with four groups of variables: forest age; human disturbances; topography (terrain slope and elevation); and landscape structure. We constructed simple and compound, with and without interaction, models beyond to the null model. The most plausible model was selected by Akaike criterion corrected for small samples (AICc). On a more local scale, the variation of AGB according to the distance to the edge was analyzed. AGB varied widely among study sites and this was partly explained by the explanatory variables, since data suited better to all models and selected variables than the null model. The most surprising result was the low overall carbon stock in the study areas (30.91 ± 11.00 Mg.ha-1). The results suggest that this pattern is mainly related to edge effects and the influence of factors directly driven by human occupation (e.g. more disturbed forests, landscapes with low forest cover and high relative occurrence of younger forests). The results also indicate that this condition of high disturbance abiotic factors, such as the topographical location, may have less importance than would be expected from previous studies. Low carbon stocks and high spatial variability indicate the need to incorporate in carbon stock estimates a finer spatial scale for climate mitigation and maintenance of ecosystem services programs in fragmented landscapes
64

Variabilidade espacial nos estoques de carbono em paisagens fragmentadas da Mata Atlântica / Spatial variability in carbon stocks in the Atlantic Forest fragmented landscapes

Isabella Romitelli 04 July 2014 (has links)
O desmatamento e a fragmentação decorrentes da expansão das atividades humanas nas paisagens florestais tropicais promovem mudanças na estrutura da paisagem, em geral com perda de florestas antigas para a agricultura ou pastagem, parcialmente compensada regionalmente com a regeneração das florestas secundárias jovens. Tal processo gera paisagens heterogêneas, com florestas secundárias em diferentes estádios de sucessão e perturbação. O estoque de carbono nestas florestas pode, assim, variar muito e essa variação pode ocorrer em diferentes escalas espaciais. O presente estudo buscou entender como as diferentes condições locais e da paisagem contribuem para o estoque de carbono. O estudo foi realizado em florestas secundárias da Mata Atlântica, no Sistema Cantareira (região sudeste do Brasil). A biomassa acima do solo (BAS) foi estimada a partir de dados de inventário florestal e modelos alométricos de biomassa. A fim de testar como a biomassa de uma floresta tropical varia em paisagens antropizadas, foram construídos modelos lineares generalizados (GLM, distribuição Gaussiana) com quatro grupos de variáveis: idade da floresta; perturbações humanas; topografia (declividade e altitude); e estrutura da paisagem. Foram construídos modelos simples, compostos, com e sem interação, além do modelo nulo. O modelo mais plausível foi selecionado pelo critério de Akaike corrigido para pequenas amostras (AICc). Numa escala mais local, a variação da BAS em função da distância à borda foi analisada. A BAS variou amplamente entre os locais de estudo e isso foi parcialmente explicado pelas variáveis explanatórias, uma vez que todos os modelos e variáveis selecionadas foram melhores do que os modelos nulos. O resultado mais surpreendente foi o baixo estoque geral de carbono nas áreas de estudo (30,91 ± 11,00 Mg.ha-1). Os resultados sugerem que este padrão está principalmente relacionado com efeitos de borda e com a influência de fatores diretamente impulsionados pela ocupação humana (como, por exemplo, florestas mais perturbadas, paisagens com baixa cobertura florestal e ocorrência relativa alta de florestas mais jovens). Os resultados indicam ainda que nesta condição de alta perturbação os fatores abióticos, tais como a localização topográfica, podem ter uma importância menor do que seria de esperar por estudos anteriores. Os baixos estoques de carbono e alta variabilidade espacial observada indicam a necessidade de se incorporar estimativas de carbono em escalas espaciais mais finas em programas de mitigação climática e de manutenção de serviços ecossistêmicos em paisagens fragmentadas / Deforestation and fragmentation resulting from the expansion of human activities in tropical forest landscapes promote changes in landscape structure, usually with loss of mature forests for agriculture or pasture, partially offset regionally with the regeneration of young secondary forests. This process generates heterogeneous landscapes with secondary forests in different stages of succession and disturbance. The stock of carbon in these forests can thus vary greatly and this variation may occur at different spatial scales. This study aimed to understand how the different local and landscape conditions contribute to carbon stock. The study was performed in secondary Atlantic Forest fragments in Cantareira System (southeastern Brazil). The above-ground biomass (AGB) was estimated by forest inventory data and allometric biomass models. In order to test how the biomass of a tropical forest varies in disturbed landscapes, generalized linear models (GLM, Gaussian distribution) were constructed with four groups of variables: forest age; human disturbances; topography (terrain slope and elevation); and landscape structure. We constructed simple and compound, with and without interaction, models beyond to the null model. The most plausible model was selected by Akaike criterion corrected for small samples (AICc). On a more local scale, the variation of AGB according to the distance to the edge was analyzed. AGB varied widely among study sites and this was partly explained by the explanatory variables, since data suited better to all models and selected variables than the null model. The most surprising result was the low overall carbon stock in the study areas (30.91 ± 11.00 Mg.ha-1). The results suggest that this pattern is mainly related to edge effects and the influence of factors directly driven by human occupation (e.g. more disturbed forests, landscapes with low forest cover and high relative occurrence of younger forests). The results also indicate that this condition of high disturbance abiotic factors, such as the topographical location, may have less importance than would be expected from previous studies. Low carbon stocks and high spatial variability indicate the need to incorporate in carbon stock estimates a finer spatial scale for climate mitigation and maintenance of ecosystem services programs in fragmented landscapes
65

Performance of slash pine (Pinus elliottii Engelm.) containerized rooted cuttings and bare-root seedlings established on five planting dates in the flatlands of western Louisiana

Akgul, Alper 29 August 2005 (has links)
The forest product industry is keenly interested in extending the normal planting season, as well as in the comparative field performance of standard nursery bare-root seedlings and containerized rooted cuttings. The effect of seasonal planting dates on survival, above and belowground biomass allocation, water relations, gas exchange attributes and foliar carbon isotope composition (δ13C) of two stock types of slash pine (Pinus elliottii Engelm.) were examined. Slash pine bare-root seedlings (BRS) and containerized rooted cuttings (CRC) were hand planted in September, November, January, March and April in three consecutive planting seasons (2000-2001, 2001-2002 and 2002-2003) on three sites with silt loam topsoils in southwestern Louisiana. First-year mean survival of CRC across all planting dates and sites was consistently high at 96 to 98%, whereas BRS survival was significantly (P < 0.0001) lower at 59 to 81% and highly variable among study sites and dates through three planting seasons. Generally, there was a negative relationship between soil moisture at the time of planting and first-year survival of BRS planted September through March in 2001-2002 and 2002-2003 planting seasons, whereas the opposite was observed only for BRS planted in April 2002 and 2003. Survival of CRC was affected very little by the variation in soil moisture. Containerized rooted cuttings had higher early above and belowground biomass, and height and diameter than did BRS. However, three years after planting the size differences between stock types disappeared or became negligible. Early size differences among trees planted September through March also decreased after three years, although September trees were tallest. Growth of the April-planted trees was poor compared to trees planted in other months. Late-planted April trees had higher δ13C values, and higher water-use efficiency in the first growing season compared to earlier planted trees. Differences in δ13C values among the planting dates disappeared in the second growing season. Net photosynthesis rates did not differ considerably between stock types or among planting dates in the second and third growing seasons. This study indicates that it is possible to extend the planting season to as early as September and as late as March by using CRC.
66

Above Ground Durability of Swedish Softwood

Blom, Åsa, Bergström, Mikael January 2005 (has links)
This thesis describes aspects of durability of Swedish softwood in above ground applications. The thesis consists of a summary of nine papers, which all aim to explain the existing variation in above ground microbial durability and moisture sensitivity of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). The methods used were two field tests, one accelerated durability test, and three water permeability tests. The main conclusions made in the study were that Norway spruce sapwood is more susceptible to discolouring fungi than heartwood. With respect to Scots pine, the only important factor for its natural durability above ground was whether the samples consisted of heartwood or of sapwood. There was also no systematic variation between pine heartwood from different stand origins in above ground conditions. Origin had no influence on durability in practice for neither spruce nor pine. Furthermore, in contradiction with traditional thinking, annual ring width and density had no influence on durability in any of the tests. The material came from two different samplings. The ‘old’ material was sampled in the beginning of the 1980s and consisted of Scots pine and Norway spruce from three different origins: the north, the central area, and the south of Sweden. The material was subjected to different handling conditions and surface and end-grain treatments. The ‘old’ material was used in a large above ground field test, carried out between 1985 and 1994. Unfortunately, the spruce sapwood and heartwood was not separated in this field test. In the field trial with the ‘old’ material, the most important factor for the durability of Norway spruce was the samples’ surface- and end-grain treatment. It was also observed that untreated spruce showed better durability than samples that were painted but without proper end-grain treatment. Samples originating from one of the stands were more sensitive towards air-drying than samples from the other two, which was reflected in a higher average moisture content and mass loss for the untreated samples. With respect to Scots pine, the most important factor was whether the sample consisted of heartwood or of sapwood. The heartwood samples were durable irrespective of their previous treatment. The Scots pine sapwood samples, on the other hand, had a very fluctuating moisture content if they were not surface- and end-painted. This was also reflected in higher mass losses in these samples. Even when properly surface- and end grain treated, the sapwood samples did not perform as well as the heartwood samples. The ‘new’ material consisted of Scots pine taken from six different stands, and Norway spruce from five different stands, all from areas in southern Sweden. The sampling was performed in order to achieve a large variation in wood properties. Thus, logs from areas with different climate and growth conditions were collected. This material was used for laboratory tests, and also for the second field test, which was evaluated after a test period of two years. In the second field test untreated Scots pine and Norway spruce samples from the ‘new’ material were investigated. Effects of origin and different tree diameters were examined. Furthermore, Scots pine was separated to heartwood and sapwood, and Norway spruce to mature and juvenile wood. The Norway spruce samples were sawn with vertical or horizontal annual rings. For the Norway spruce in the second field test, vertical annual rings were shown to be very beneficial for avoiding crack formation, while samples with horizontal annual rings displayed a large number of cracks. Despite this, the larger number of cracks did not result in a higher moisture content or more fungal discoloration. Juvenile wood had a slightly higher average discolouring fungal growth grading than the other spruce samples. For Scots pine, the only factor of importance was whether the samples consisted of heartwood or of sapwood. Annual ring width, density and origin had no significant effect on either fungal growth or moisture uptake. This observation held for both Norway spruce samples and Scots pine samples. An accelerated test was run in order to investigate Norway spruce sapwood and heartwood with respect to their differences in durability towards discolouring fungi and moisture uptake. The Mycologg method was used to accelerate fungal growth during a number of forced moisture cycles. The results showed that sapwood was much more sensitive to discolouring fungi than heartwood. Sapwood also recorded a higher average moisture content than heartwood. The differences that were observed between the types of samples were not due to annual ring width, density or origin. It was observed that Norway spruce sapwood samples and heartwood samples showed differences in liquid water permeability. This observation was made especially evident in a droplet absorption test. Water droplets were absorbed much faster on the sapwood samples in comparison with the heartwood samples. This higher affinity to water suggested that a sapwood surface would reach a higher moisture content than a heartwood surface. This observation provides a major explanation of why the sapwood samples showed poorer durability towards discolouring fungi in the Mycologg trials.
67

Performance of slash pine (Pinus elliottii Engelm.) containerized rooted cuttings and bare-root seedlings established on five planting dates in the flatlands of western Louisiana

Akgul, Alper 29 August 2005 (has links)
The forest product industry is keenly interested in extending the normal planting season, as well as in the comparative field performance of standard nursery bare-root seedlings and containerized rooted cuttings. The effect of seasonal planting dates on survival, above and belowground biomass allocation, water relations, gas exchange attributes and foliar carbon isotope composition (&#948;13C) of two stock types of slash pine (Pinus elliottii Engelm.) were examined. Slash pine bare-root seedlings (BRS) and containerized rooted cuttings (CRC) were hand planted in September, November, January, March and April in three consecutive planting seasons (2000-2001, 2001-2002 and 2002-2003) on three sites with silt loam topsoils in southwestern Louisiana. First-year mean survival of CRC across all planting dates and sites was consistently high at 96 to 98%, whereas BRS survival was significantly (P < 0.0001) lower at 59 to 81% and highly variable among study sites and dates through three planting seasons. Generally, there was a negative relationship between soil moisture at the time of planting and first-year survival of BRS planted September through March in 2001-2002 and 2002-2003 planting seasons, whereas the opposite was observed only for BRS planted in April 2002 and 2003. Survival of CRC was affected very little by the variation in soil moisture. Containerized rooted cuttings had higher early above and belowground biomass, and height and diameter than did BRS. However, three years after planting the size differences between stock types disappeared or became negligible. Early size differences among trees planted September through March also decreased after three years, although September trees were tallest. Growth of the April-planted trees was poor compared to trees planted in other months. Late-planted April trees had higher &#948;13C values, and higher water-use efficiency in the first growing season compared to earlier planted trees. Differences in &#948;13C values among the planting dates disappeared in the second growing season. Net photosynthesis rates did not differ considerably between stock types or among planting dates in the second and third growing seasons. This study indicates that it is possible to extend the planting season to as early as September and as late as March by using CRC.
68

Compliant pediatric prosthetic knee

Mahler, Sebastian 01 June 2007 (has links)
We have designed and examined a compliant knee mechanism that may offer solutions to problems that exist for infants and toddlers who are just learning to walk. Pediatric prosthetic knees on the market today are not well designed for infants and toddlers for various reasons. Children at this age need a prosthetic that is light in weight, durable, and stable during stance. Of the eleven knees on the market for children, all but three are polycentric or four-bar knees, meaning they have multiple points of movement. Polycentric knees are popular designs because they offer the added benefit of stable stance control and increased toe clearance, unfortunately this type of knee is often too heavy for young children to wear comfortably and is not well suited for harsh environments such as sand or water, common places children like to play. The remaining three knees do not offer a stance control feature and are equally vulnerable to harsh environments due to ball bearing hinges. Compliant mechanisms offer several design advantages that may make them suitable in pediatric prosthetic knees -- light weight, less susceptible to harsh environments, polycentric capable, low part count, etc. Unfortunately, they present new challenges that must be dealt with individually. For example compliant mechanisms are typically not well suited in applications that need adjustability. This problem was solved by mixing compliant mechanism design with traditional mechanism design methods. This paper presents a preliminary design concept for a compliant pediatric prosthetic knee. The carbon fiber composite spring steel design was first built and then evaluated using Finite Element Analysis. The prototype's instant center was plotted using the graphical method. From our analysis position, force and stress information was gathered for a deflection up to 120 degrees. The instant centers that were plotted indicate that the knee has good potential in offering adequate stability during stance.
69

Performance de modelo climárico de previsão da precipitação pluviométrica no Estado da Paraíba. / Performance of climatic model of precipitation forecast in Paraíba State.

LIMA, Nielza Macedo 19 October 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-10-19T18:41:21Z No. of bitstreams: 1 NIELZA MACEDO LIMA - DISSERTAÇÃO PPGMet 2001..pdf: 25624730 bytes, checksum: b3ea3a96769b05231b9b60ab18dea2b1 (MD5) / Made available in DSpace on 2018-10-19T18:41:21Z (GMT). No. of bitstreams: 1 NIELZA MACEDO LIMA - DISSERTAÇÃO PPGMet 2001..pdf: 25624730 bytes, checksum: b3ea3a96769b05231b9b60ab18dea2b1 (MD5) Previous issue date: 2001-12-18 / CNPq / O presente trabalho objetivou apresentar uma metodologia de previsão das chuvas que ocorrem no Estada da Paraíba, tendo por base o método das proporções apresentado por Silva (1988). Foram considerados 72 postos pluviométricos com mais de trinta anos de registros completos, distribuídos em três mesorregiões da Paraíba: mesorregião Ocidental (Sertões), Central (Cariris) e Oriental (Litoral, Agreste e Zona da Mata). Em cada mesorregião defmiu-se a correspondente estação chuvosa (EC) e diferentes sub-divisões das mesmas. As proporções Zj, razão entre as chuvas acumuladas no primeiro período (Xj) da EC e as chuvas de toda a EC, foram ajustadas ao modelo probabilístico Beta, usado para o cálculo dos quintis (primeiro e quarto) e da probabilidade de ocorrência de chuvas superior à média climatológica do segundo período (Yj) da EC. Avaliou-se a performance do modelo prognóstico por mesorregião nos anos de 1996 a 2001, inclusive. Nos anos de 1996 e 2000, com grande ocorrência de chuvas acima da média em Yj em todas as mesorregiões estudadas, o índice de acerto foi superior aos 80%, exceto para a EC8 em 2000. No ano de 1998, um ano muito seco, o índice foi inferior aos 80%, quando do prognóstico do total pluviométrico mínimo esperado. De um modo geral, a metodologia apresentada se mostrou consistente e de grande utilidade para a previsão de secas no Estado da Paraíba. / A methodology for forescating the acumulatcd rainfall (AR) in differcnt locations and mesoregions of Paraíba State, based on a model proposcd by Silva (1985,1988), was the objective of this study. A network of 72 rain stations, associated with three mesoregions of Paraíba State, were used. For each State mesoregion (Eastcrn, Central and Western) a rainy scason (RS) was established, with different subdivisions of them. The Beta probability distribution model was ajusted to lhe ratio betwccn lhe AR of the First period of the RS (Xi) and the total AR of the rainy season. That probabilislic model was used in the determination of statistical parameters (first - Ql and forth - Q4 quintis) and the probability of oceurrence of AR, in the second period of the RS, greater than the average of that same period, for each selected location. It was observed that in 1999 and 2000 therc were a great number of accumulated rainfall greater than the average of the second period (Yi) of the RS, for each of selected stations. The index of success, for the AR forecasted in those years, was greater than 80%, except for the RS denominated of EC8 in 2000. In 1998, considered a very dry year, the success index for oceurrence of the minimun AR was less than the expected valuc. Na important conclusion in that, the methodology presented is appropriated and seems to be am important tool for forecasting the oceurrence of drought in Paraíba State.
70

Zančka a její význam při utváření pozice na trhu na příkladě energetické společnosti / Brand and its significance while forming the position on the market by way for example of an enery company

VONDRÁKOVÁ, Markéta January 2008 (has links)
The submitted diploma work combines available information resources from the area of general brand management with current challenges which the Brand Management faces within the power industry in the dynamically developing Czech market with significant globalization features. This creates a structure of secondary information resources, practical experience and drawn conclusions which have never been published and are primarily relevant to optimisation of the E.ON brand but important for the entire power industry sector due to its focus and they surpass their branch in the brand migration area

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