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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.
1

Comparing survival and growth among three different planting stocks of water oak (Quercus nigra) and white oak (Quercus alba) on lands damaged by Hurricane Katrina

Gentry, Austin S 01 May 2020 (has links)
Bareroot, conventional containerized, and large potted EKOgrown® seedlings of water oak (Quercus nigra) and white oak (Q. alba) were planted on two Hurricane Katrina damaged sites in south Mississippi. After two growing seasons, white oak exhibited greater survival (61.1%) than water oak (48.8%) and greater height growth (WHO = 7.4 cm, WAO = 1.4 cm). Water oak had greater groundline diameter (GLD) growth (3.3 mm) and greater second-year height growth (WHO = 2.5 cm, WAO = 9.6 cm). Second-year development could lead to greater height growth by water oak. Bareroot seedlings outperformed other planting stocks in survival and height growth, but EKO seedlings exhibited greater GLD growth. Even though EKO seedlings had greatest GLD growth, they exhibited the least overall height growth of all planting stocks (1.9 cm). Based on seedling cost and performance in this study, planting bareroot seedlings are the most efficient method to artificially regenerate oak forests.
2

Changes in green liquor dregs after leaching with various acidic media

Skagerkvist, Mio January 2017 (has links)
Green liquor dreg (GLD) is a residual product that could be a solution to the problem with acid rock drainage. More information about how this material reacts and is affected when in contact with acid rock drainage (ARD) is needed. Different acidic media was used to investigate trace element leaching and the possible spectral changes using FTIR. It was possible to detect changes between samples based on the exposure for different acidic conditions. Most peaks were found below 1 500 cm-1 which complicates the interpretation. For enabling the use of multivariate analysis the spectral data needed to be pre-treated and after this it was possible to see groupings and directions based on exposure. Different tendencies are seen for the trace elements, where some element leaching increased at lower pH and some elements decreased leaching at lower pH. This could partly be due to the formation of salts with low solubility such as gypsum and anglesite when leached with sulphuric acid.
3

Rapid Detection of Grapevine Leafroll-associated virus Type 3 using the reverse transcription loop-mediated amplification method

Walsh, Helen Ann January 2013 (has links)
Grapevine Leafroll disease (GLD), one of the most destructive diseases of grapevines, has been found in every country where grapevines are grown. Grapevine Leafroll associated virus type 3 (GLRaV-3), one of several viruses associated with GLD globally, is the most prevalent virus in South African grapevines and therefore control of GLRaV-3 takes high priority in any strategy aimed at control of GLD. GLD can be controlled through the use of an integrated strategy which includes using certified plant material, controlling insect vectors through use of systemic insecticides and the removal of infected vines by roguing. Infected individuals are identified each autumn, using either symptom display (in red cultivars, where infected individuals display interveinal reddening and downward rolling of leaves) or ELISA (in symptomless white cultivars). ELISA is laborious, time consuming and relatively insensitivity compared to molecular techniques and a simpler, more rapid and more sensitive means of indentifying GLRaV-3 infected vines is required. A simple RNA extraction procedure combined with a single-tube reverse transcriptase loop-mediated amplification (RT-LAMP) has been developed which allows for the rapid, simple detection of GLRaV-3. Using RT-LAMP, a viral target can be amplified in 2 hours under isothermal conditions. This GLRaV-3 specific RTLAMP uses hydroxy napthol blue (HNB), a colourimetric indicator that changes from violet to sky blue only where a positive RT-LAMP reaction has occurred, making results quick and easy to interpret. The sensitivity of this technique was compared to ELISA and nested PCR by pooling samples at varying ratios of healthy to infected plants. Using nested PCR and RT-LAMP 1 infected sample could be detected amongst 50 healthy individuals while ELISA could only detect 1 amongst 30 infected making RT-LAMP more sensitive than ELISA. Further RT-LAMP could be performed in 2 hours compared to nested PCR and ELISA’s 8 and 48 hours respectively. Based on these results, RT-LAMP is viable alternative for ELISA for the detection of GLRaV-3 in the field. RT-LAMP was also tested for its ability to detect GLRaV-3 in grapevine rootstocks where, due to low viral titres and erratic distribution, it is notoriously difficult to detect. The rootstocks which were used for testing of GLRaV-3 had been tested in a previous study and it was found that only 28% of samples tested positive after 33 months (post inoculation). Using RT-LAMP, 78% of samples tested positive for GLRaV-3. Although further testing must be done, RT-LAMP may also be a viable alternative for testing grapevine rootstocks for GLRaV-3 infection. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Microbiology and Plant Pathology / unrestricted
4

Metodologia para adequação do uso de força motriz em processos agrícolas / Methodology for adequacy of electric traction in agricultural processes

Teixeira, Carlos Alberto 26 February 2002 (has links)
Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-02-10T09:30:04Z No. of bitstreams: 1 texto completo.pdf: 1313508 bytes, checksum: 92bc999bec99b013ba3b61d91c3d4ace (MD5) / Made available in DSpace on 2017-02-10T09:30:04Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1313508 bytes, checksum: 92bc999bec99b013ba3b61d91c3d4ace (MD5) Previous issue date: 2002-02-26 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Nos últimos anos, a industrialização e o crescimento econômico, no Brasil vêm causando aumento na demanda de energia elétrica, associados às crescentes inovações tecnológicas. A falta de investimentos no setor energético, que causou racionamento de energia elétrica a partir de junho de 2001, aliadas à sazonalidade dos recursos necessários para geração de energia hidroelétrica, torna a racionalização do uso de energia elétrica uma ferramenta de apoio imprescindível ao crescimento sustentável do País. A utilização de energia elétrica nos diversos setores é de cerca de 49 % (setor industrial), 24 % (setor residencial), 12 % (setor comercial), 12 % (setor governamental) e 3 % (setor rural). No setor industrial, o uso final de energia elétrica é distribuído da seguinte forma: cerca de 49 % para força motriz, 32 % para fornos, 10 % para caldeira, 7 % para eletrólise química e 2 % para iluminação. Os motores elétricos representam cerca de 35 % do consumo global de energia elétrica no País. São mais de 10 milhões de motores elétricos, em funcionamento. O racionamento de energia elétrica determinado pelo governo federal incentiva a adoção de medidas de racionalização do uso de energia elétrica, dentre elas o uso de força motriz. Dentre todas as opções de gerenciamento do lado da demanda, a adequação de força motriz é economicamente a mais viável . No complexo agroindustrial, há necessidade de estudos voltados para a racionalização do uso de energia elétrica em fábricas de pré-processamento de grãos, em geral, e fábricas de ração em particular, haja vista o grande potencial de economia do uso de energia elétrica que representam. Dentre os estudos e medidas que devem ser contemplados, visando ao uso racional de energia elétrica, destacam-se a utilização de inversores de freqüência acoplados a transportadores de grãos e o desenvolvimento de programas computacionais para adequação de força motriz. A utilização de inversores de freqüência é útil em razão da possibilidade de racionalização do uso de energia elétrica, da automação, controle da corrente de partida e da potência reativa demandada. Já a adequação de força motriz e consequentemente, do processo, gera a otimização de recursos de energia e economia disponíveis. Estudos realizados sobre a utilização de energia elétrica na agricultura pelo Departamento de Engenharia Agrícola da Universidade Federal de Viçosa, apresentaram um potencial médio de 25 % de economia e conservação de energia elétrica, em ações de adequação de força motriz e utilização de inversor de freqüência. As possíveis causas do desperdício de energia elétrica, em unidades armazenadoras, são, principalmente, as seguintes: a falta de conhecimento quanto à carga dos transportadores a ser trabalhada; as diferenças nas condições de teste dos equipamentos dos fabricantes, em relação às condições dos equipamentos em funcionamento; os sucessivos coeficientes de segurança embutidos nos projetos; o desbalanceamento das fases e do nível de tensão na rede de distribuição de energia elétrica, a não adoção de motores eficientes e aparelhos eletrônicos com ênfase no comando, proteção e acionamentos; e o número de horas de funcionamento anual não otimizado. / Through the past years, the industrialization and the economic growth have increased the demand of electric energy, associated with the increasing technological innovations. The lack of investments in the electric power generation, have caused a necessity of reducing the use of electrical energy in Brazil, since July 2001. Due to this fact, allied to the seasoning resources needed for the generation of hydroelectric energy, to make a support tool out of rationalization of electrical energy consumption is very helpful to the growth of the country. The use of electric energy in Brazil are estimated by: 49 % in the industrial sector, 24 % in the residential sector, 12 % in the commercial sector, 12 % in the government sector and 3 % in the rural sector. In the industrial sector, the final use of electric energy is distributed in the following way: 49 % for motive power, 32 % for ovens, 10 % for boilers, 7 % for chemical electrolysis and 2 % for lighting. The electric motors represent about 35 % of the global consumption of electric energy in Brazil. There are more than 10 million electric motors in operation. The rationalization of electric energy proposed by the Federal Government strongly motivates the use of measures that rationalize the use of electric energy, such as decreasing the use of the motive force. Among all the options of controlling the demand, the adaptation of motive power is the most viable economically. In the agriculture-industrial complex, the rationalization of the use of electric energy in pre- processing grain factories (generally animal ration factories) needs to be studied carefully due to the great saving of energy consumption that it represents. Through the midst of measures and studies that should be considered for aiming the rational use of electrical energy, are most important the use of frequency inverters attached to grain transporters and the development of motive power adaptation software. The use of frequency inverters makes it more possible to rationalize the electric energy consumption, the automation, the control of the start current and the reactive power demanded; wile the adaptation of the motive power, and consequently of the whole process, creates better use over the power and economical resources available. Studies accomplished in the Federal University Viçosa, at the Agricultural Engineering Department, by the Agriculture Energy Area, presented an average potential of 25 % economy and conservation of electric energy in use of adaptation of motive power and frequency inverter. The possible causes of the waste of electric energy in the storage units, are due to the lack of knowledge on conveyors’ loads which will be worked with and because the equipment’s conditions from the factory’s tests differ from the conditions of the equipment’s in operation. Also, successive coefficients of safety are embedded in the projects, the voltage fluctuation of the phases and of the tension level in the net of distribution of electric energy is unbalanced, the non adoption of efficient motors and electronic equipments with emphasis in the command, lack of protection and activation and non controlled number of hours of operation per year. / Dissertação importada do Alexandria
5

An Empirical Comparison of Four Data Generating Procedures in Parametric and Nonparametric ANOVA

Zhang, Anquan 01 May 2011 (has links)
The purpose of this dissertation was to empirically investigate the Type I error and power rates of four data transformations that produce a variety of non-normal distributions. Specifically, the transformations investigated were (a) the g-and-h, (b) the generalized lambda distribution (GLD), (c) the power method, and (d) the Burr families of distributions in the context of between-subjects and within-subjects analysis of variance (ANOVA). The traditional parametric F tests and their nonparametric counterparts, the Kruskal-Wallis (KW) and Friedman (FR) tests, were selected to be used in this investigation. The four data transformations produce non-normal distributions that have either valid or invalid probability density functions (PDFs). Specifically, the data generating procedures will produce distributions with valid PDFs if and only if the transformations are strictly increasing - otherwise the distributions are considered to be associated with invalid PDFs. As such, the primary objective of this study was to isolate and investigate the behaviors of the four data transformation procedures themselves while holding all other conditions constant (i.e., sample sizes, effect sizes, correlation levels, skew, kurtosis, random seed numbers, etc. all remain the same). The overall results of the Monte Carlo study generally suggest that when the distributions have valid probability density functions (PDFs) that the Type I error and power rates for the parametric (or nonparametric) tests were similar across all four data transformations. It is noted that there were some dissimilar results when the distributions were very skewed and near their associated boundary conditions for a valid PDF. These dissimilarities were most pronounced in the context of the KW and FR tests. In contrast, when the four transformations produced distributions with invalid PDFs, the Type I error and power rates were more frequently dissimilar for both the parametric F and nonparametric (KW, FR) tests. The dissimilarities were most pronounced when the distributions were skewed and heavy-tailed. For example, in the context of a parametric between subjects design, four groups of data were generated with (a) sample sizes of 10, (b) standardized effect size of 0.50 between groups, (c) skew of 2.5 and kurtosis of 60, (d) power method transformations generating distributions with invalid PDFs, and (e) g-and-h and GLD transformations both generating distributions with valid PDFs. The power results associated with the power method transformation showed that the F-test (KW test) was rejecting at a rate of .32 (.86). On the other hand, the power results associated with both the g-and-h and GLD transformations showed that the F-test (KW test) was rejecting at a rate of approximately .19 (.26). The primary recommendation of this study is that researchers conducting Monte Carlo studies in the context described herein should use data transformation procedures that produce valid PDFs. This recommendation is important to the extent that researchers using transformations that produce invalid PDFs increase the likelihood of limiting their study to the data generating procedure being used i.e. Type I error and power results may be substantially disparate between different procedures. Further, it also recommended that g-and-h, GLD, Burr, and fifth-order power method transformations be used if it is desired to generate distributions with extreme skew and/or heavy-tails whereas third-order polynomials should be avoided in this context.
6

Full-scale seismic testing of a reinforced concrete moment frame using mobile shakers

Wright, Timothy R. 07 January 2016 (has links)
A prototype reinforced concrete moment frame representative of low-rise office buildings in the Central and Eastern United States from the 1950s-1970s was designed and selected for evaluation under seismic loads. A plane frame specimen from the prototype was incorporated into the design of a test-bed of four full-scale, side-by-side nominally identical structures that could be evaluated independently. The testing of the first frame serves as the topic of this dissertation. The specimen was two bays x two stories x 9-ft. wide. A new method for testing full-scale structures under seismic loads was proposed that used a hydraulic linear inertial shaker (LIS) to impart seismic loads. The response of the structure was monitored using 155 strain gages, 38 linear variable differential transformers, six string potentiometers, and 42 accelerometers. The response of the frame to a series of 25 load histories using the nees@UCLA LIS was marked by gradual structural softening and minimal yielding of the steel reinforcing throughout the structure. At a first interstory drift of 1.5% some yielding of the reinforcing bars was measured. Between 1.5% and 2% first interstory drift, a global sway mechanism formed when the failure of a splice at the base of the first story west column led to a cascading set of failures within other first-story column splices. The experimental behavior suggests previous scaled testing of similar structures may have inadequately represented the vulnerability column splices. The design of the test-bed, response of the structure to seismic loads, qualitative evaluation of the test method, and implications on future research are discussed.
7

DEFLEGER : deslocamento e flexibilidade de cargas no gerenciamento de energia residencial

Castro, Tiago Bornia de 29 June 2017 (has links)
Submitted by Patrícia Cerveira (pcerveira1@gmail.com) on 2017-06-14T19:17:38Z No. of bitstreams: 1 Tiago Bornia de Castro Dissertação.pdf: 4966184 bytes, checksum: 7e49563b573266804e94e53d4b7db605 (MD5) / Approved for entry into archive by Biblioteca da Escola de Engenharia (bee@ndc.uff.br) on 2017-06-29T13:48:38Z (GMT) No. of bitstreams: 1 Tiago Bornia de Castro Dissertação.pdf: 4966184 bytes, checksum: 7e49563b573266804e94e53d4b7db605 (MD5) / Made available in DSpace on 2017-06-29T13:48:38Z (GMT). No. of bitstreams: 1 Tiago Bornia de Castro Dissertação.pdf: 4966184 bytes, checksum: 7e49563b573266804e94e53d4b7db605 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Smart grids surgem como a evolução da rede elétrica. Sua proposta é incorporar redes de telecomunicações à rede elétrica, possibilitando o monitoramento em tempo real, rápida detecção/tratamento de falhas, maior facilidade de integração de fontes renováveis entre outros serviços. Porém sua implantação afeta a manutenção do equilíbrio entre a produção e o consumo de energia, que é essencial para a estabilidade da rede elétrica. Com o aumento de fontes renováveis, a predição da energia produzida torna-se mais difícil, devido à natureza intermitente dessas fontes. Fontes de energia renováveis dependem de fatores ambientais que tornam a previsão de geração de energia mais complexa e menos precisa. Portanto, existe uma mudança de paradigma com a modernização de rede de energia: na rede tradicional, a produção adapta-se à demanda, mas nas smart grids, a demanda adapta-se à produção e faz com que o consumo de usuário seja mais eficiente. Os programas de Gerenciamento pelo Lado da Demanda (GLD) surgem como uma solução para ajustar o consumo do usuário à geração. GLD são ações ou decisões tomadas pela empresa de energia para alterar ou modelar o padrão de consumo do usuário. A proposta deste trabalho é a criação de mecanismos de gerenciamento pelo lado da demanda direcionado para o usuário residencial no Brasil diante da implantação das smart grids. Foi criado o DEFLEGER-ECO, mecanismo de economia de energia elétrica usando tarifa branca, nova forma de tarifação que entrará em vigor a partir de 2018, e DEFLEGER-EMER, mecanismo emergencial voltado a redução de demanda durante eventos emergenciais. Devido a inexistência de uma ferramenta para a validação dos mecanismos, também foi desenvolvida uma ferramenta de simulação que é fruto da integração de dois simuladores, o NS-3 e o EnergyPlus. Os modelos foram simulados em quatro perfis de residências com a finalidade de avaliar seus desempenhos. Os mecanismos funcionaram conforme o esperado e uma de das principais contribuições é a possibilidade de atender diversos perfis de usuários residenciais. / Smart grids arise as the power grid evolution. The key idea is to incorporate telecommunications networks to the power grid, allowing real-time monitoring, fast detection/treatment failures, easier integration of renewable sources, and other services. Nevertheless the implementation of smart grids affects the maintenance of the balance between energy production and consumption, which is the essential for the power grid stability. With the increase in the number of renewable sources, prediction of energy produced becomes more difficult due to the intermittent nature of these sources. Renewable power sources depend on environmental factors that make power generation prediction more complex and less accurate. Therefore, there is a paradigm change with the grid modernization: in traditional grid energy, production adapts to the demand, but in smart grids, demand adapts to the production and makes user consumption more efficient. Demand Side Management (DSM) programs arise as one of the solutions to adjust user consumption to supply. DSM is an action or decision made by utility to alter and model user pattern of consumption. The purpose of this work is the creation of DSM mechanisms for Brazilian users. DEFLEGER-ECO was created, an electric energy saving mechanism using the white tariff, a new form of charging that will take effect from 2018, and DEFLEGEREMER, an emergency mechanism aimed at reducing demand during emergency events. Due to the lack of a tool for the validation of the mechanisms, a simulation tool was also developed, which is the result of the integration of two simulators, NS-3 and EnergyPlus. The models were simulated in four residential profiles in order to evaluate their performance. The mechanisms worked as expected and one of the main contributions is the possibility to serve several profiles of residential users.
8

Generic design and investigation of solar cooling systems

Saulich, Sven January 2013 (has links)
This thesis presents work on a holistic approach for improving the overall design of solar cooling systems driven by solar thermal collectors. Newly developed methods for thermodynamic optimization of hydraulics and control were used to redesign an existing pilot plant. Measurements taken from the newly developed system show an 81% increase of the Solar Cooling Efficiency (SCEth) factor compared to the original pilot system. In addition to the improvements in system design, new efficiency factors for benchmarking solar cooling systems are presented. The Solar Supply Efficiency (SSEth) factor provides a means of quantifying the quality of solar thermal charging systems relative to the usable heat to drive the sorption process. The product of the SSEth with the already established COPth of the chiller, leads to the SCEth factor which, for the first time, provides a clear and concise benchmarking method for the overall design of solar cooling systems. Furthermore, the definition of a coefficient of performance, including irreversibilities from energy conversion (COPcon), enables a direct comparison of compression and sorption chiller technology. This new performance metric is applicable to all low-temperature heat-supply machines for direct comparison of different types or technologies. The achieved findings of this work led to an optimized generic design for solar cooling systems, which was successfully transferred to the market.

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