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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.
111

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
112

Lignocellulosic Ethanol Production Potential and Regional Transportation Fuel Demand

Daianova, Lilia January 2011 (has links)
Road traffic dominates in domestic Swedish transportation and is highly dependent on fossil fuels, petrol and diesel. Currently, the use of renewable fuels in transportation accounts for less than 6% of the total energy use in transport. The demand for bioethanol to fuel transportation is growing and cannot be met through current domestic production alone. Lignocellulosic ethanol derived from agricultural crop residues may be a feasible alternative source of ethanol for securing a consistent regional fuel supply in Swedish climatic conditions.  This licentiate thesis focuses on regional transport fuel supply by considering local small-scale ethanol production from straw. It presents the results of investigations of regional transport fuel supply with respect to minimising regional CO2 emissions, cost estimates for transport fuel supply, and the availability of lignocellulosic resources for small-scale ethanol production. Regional transport fuel demand between the present and 2020 is also estimated. The results presented here show that significant bioethanol can be produced from the straw and Salix available in the studied regions and that this is sufficient to meet the regions’ current ethanol fuel demand.  A cost optimisation model for regional transport fuel supply is developed and applied for two cases in one study region, one when the ethanol production plant is integrated with an existing CHP plant (polygeneration), and one with a standalone ethanol production plant. The results of the optimisation model show that in both cases the changes in ethanol production costs have the biggest influence on the cost of supplying the regional passenger car fleet with transport fuel, followed by the petrol price and straw production costs.  By integrating the ethanol production process with a CHP plant, the costs of supplying regional passenger car fleet with transport fuel can be reduced by up to a third. Moreover, replacing petrol fuel with ethanol can cut regional CO2 emissions from transportation by half.
113

Impact of wireless losses on the predictability of end-to-end flow characteristics in Mobile IP Networks

Bhoite, Sameer Prabhakarrao 17 February 2005 (has links)
Technological advancements have led to an increase in the number of wireless and mobile devices such as PDAs, laptops and smart phones. This has resulted in an ever- increasing demand for wireless access to the Internet. Hence, wireless mobile traffic is expected to form a significant fraction of Internet traffic in the near future, over the so-called Mobile Internet Protocol (MIP) networks. For real-time applications, such as voice, video and process monitoring and control, deployed over standard IP networks, network resources must be properly allocated so that the mobile end-user is guaranteed a certain Quality of Service (QoS). As with the wired and fixed IP networks, MIP networks do not offer any QoS guarantees. Such networks have been designed for non-real-time applications. In attempts to deploy real-time applications in such networks without requiring major network infrastructure modifications, the end-points must provide some level of QoS guarantees. Such QoS guarantees or QoS control, requires ability of predictive capabilities of the end-to-end flow characteristics. In this research network flow accumulation is used as a measure of end-to-end network congestion. Careful analysis and study of the flow accumulation signal shows that it has long-term dependencies and it is very noisy, thus making it very difficult to predict. Hence, this work predicts the moving average of the flow accumulation signal. Both single-step and multi-step predictors are developed using linear system identification techniques. A multi-step prediction error of up to 17% is achieved for prediction horizon of up to 0.5sec. The main thrust of this research is on the impact of wireless losses on the ability to predict end-to-end flow accumulation. As opposed to wired, congestion related packet losses, the losses occurring in a wireless channel are to a large extent random, making the prediction of flow accumulation more challenging. Flow accumulation prediction studies in this research demonstrate that, if an accurate predictor is employed, the increase in prediction error is up to 170% when wireless loss reaches as high as 15% , as compared to the case of no wireless loss. As the predictor accuracy in the case of no wireless loss deteriorates, the impact of wireless losses on the flow accumulation prediction error decreases.
114

Identification of the radionuclides in spent nuclear fuel that may be detected by Compton suppression and gamma-gamma coincidence methods

Schreiber, Samuel Stuart 01 August 2011 (has links)
The nuclides present in spent nuclear fuel are categorized according to their capacity for detection by Compton suppression or gamma-gamma coincidence methods. The fifty nuclides with the highest activities in spent fuel are identified, their decay schemes analyzed, and the best detection scheme for each is recommended. / text
115

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
116

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
117

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
118

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
119

Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony Unknown Date (has links)
Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
120

Aspectos relacionados com o uso de parasitoides no manejo integrado da mosca minadora no meloeiro / Aspects related to the use of parasitoids in the integrated management of leafminer in the melon

Silva, Francisco Edivino Lopes da 29 February 2016 (has links)
Made available in DSpace on 2016-08-12T19:15:36Z (GMT). No. of bitstreams: 1 FranciscoELS_DISSERT.pdf: 593076 bytes, checksum: e225bf4fa3857eb2f3da5c8dcc0be47d (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The melon (Cucumis melo L.) is one of the main cucurbits grown in northeastern Brazil. Among the main obstacles to the production of melon, the leafminer Liriomyza sativae (Diptera: Agromyzidae) stands out as one of the main pests. Since the discovery of natural enemies Opius scabriventris (Hymenoptera: Braconidae) and Neochrysocharis sp. (Hymenoptera: Eulophidae) in melon production areas RN and CE, increased the prospects of the use of biological control in this region. However, information on the preferred instar and competition among parasitoids Opius scabriventris and Neochrysocharis sp. still are scarce. Furthermore, the conservation of these parasitoids in agrosystem is of fundamental importance to the MIP, therefore, it is necessary to know the action of plant protection products on O. scabriventris and Neochrysocharis sp. Therefore, the objective of this study was to define the preferred instar O. scabriventris and Neochrysocharis sp., Evaluate the competition between these two species and the toxicity of insecticides used in melon crop on these two parasitoids in laboratory conditions. To determine the preferred instar were exposed leafminer larvae first, second and third instar for the two species of parasitoids. The competition studies were to assess the simultaneous parasitism O. scabriventris x Neochrysocharis sp. in proportions of 1x1, 2x1, 1x2 for the second and third larval instar L. sativae. The toxicity of insecticides to parasitoids were evaluated in bioassays through contact of parasitoids with freshly contaminated surface. The treatments were: abamectin, clorantraniliprole, cyromazine, espinetoram, spinosad and distilled water (control). Later, with the parasitoids that survived the tests of toxicity were evaluated sublethal effects of pesticides that caused lower mortality on the parasitism capacity. Regarding prefered instar tests, O. scabriventris preferably parasitized second instar larvae, while Neochrysocharis sp. preferred third instar larvae. Regarding competition assays, it was found that parasitoids O. scabriventris and Neochrysocharis sp. competed for larvae second and third instar L. sativae. Regarding toxicity tests, the abamectin, espinetoram and spinosad were the most toxic to the parasitoid O. scabriventris and Neochrysocharis sp. The clorantraniliprole and cyromazine insecticide caused reduction in parasitism capacity of O. scabriventris / O meloeiro (Cucumis melo L.) é uma das principais cucurbitáceas cultivadas na região Nordeste do Brasil. Dentre os principais entraves à produção do meloeiro, a mosca minadora Liriomyza sativae (Diptera: Agromyzidae) se destaca como uma das principais pragas. Desde a constatação dos inimigos naturais Opius scabriventris (Hymenoptera: Braconidae) e Neochrysocharis sp. (Hymenoptera: Eulophidae) em áreas de produção de melão do RN e CE, cresceram as perspectivas da utilização do controle biológico nessa região. No entanto, informações sobre o instar preferencial e a competição entre os parasitoides Opius scabriventris e Neochrysocharis sp. são escassas. Além disso, a conservação desses parasitoides no agrossistema é de fundamental importância para o MIP, sendo assim, é necessário conhecer a ação dos produtos fitossanitários sobre O. scabriventris e Neochrysocharis sp. Portanto, o objetivo do presente trabalho foi definir o instar preferencial de O. scabriventris e Neochrysocharis sp., avaliar a competição entre essas duas espécies e a toxidade de inseticidas utilizados na cultura do meloeiro sobre esses dois parasitoides em condições de laboratório. Para determinar o instar preferencial, foram expostas larvas de mosca minadora de primeiro, segundo e terceiro instar para as duas espécies de parasitoides. Os estudos de competição consistiram em avaliar o parasitismo simultâneo de O. scabriventris x Neochrysocharis sp. nas proporções de 1x1, 2x1, 1x2 para larvas de segundo e terceiro instar de L. sativae. A toxicidade dos inseticidas aos parasitoides foram avaliados em ensaios biológicos por meio do contato dos parasitoides com superfície recém-contaminada. Os tratamentos foram: abamectina, clorantraniliprole, ciromazina, espinetoram, espinosade e água destilada (Testemunha). Posteriormente, com os parasitoides que sobreviveram aos ensaios de toxicidade, foram avaliados os efeitos subletais dos inseticidas que ocasionaram menor mortalidade sobre a capacidade de parasitismo. Quanto aos ensaios de ínstar preferencial, O. scabriventris parasitou preferencialmente larvas de segundo instar, enquanto que Neochrysocharis sp. preferiu larvas de terceiro instar. Em relação aos ensaios de competição, verificou-se que os parasitoides O. scabriventris e Neochrysocharis sp. competiram por larvas segundo e terceiro instar de L. sativae. Em relação aos ensaios de toxicidade, os inseticidas abamectina, espinetoram e espinosade foram os mais tóxicos aos parasitoides O. scabriventris e Neochrysocharis sp. Os inseticidas clorantraniliprole e ciromazina ocasionaram redução na capacidade de parasitismo de O. scabriventris

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