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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.
141

Estimativa da evapotranspiração real por meio de imagens do satélite landsat 8 / Estimating real evapotranspiration using landsat 8 images

Silva, Bruno Bonemberger da 10 December 2014 (has links)
Made available in DSpace on 2017-07-10T19:24:00Z (GMT). No. of bitstreams: 1 Bruno Bonemberger_ da Silva.pdf: 2742297 bytes, checksum: caffe80e4c328becd1f17a199c916184 (MD5) Previous issue date: 2014-12-10 / The estimate evapotranspiration is a key factor in sustainable water management in irrigated agriculture, the actual crop water requirement established objectively, without generating waste of energy and water by excessive irrigation, and, on the other side, without compromising the agricultural production by its deficit. In this sense, the study aimed to estimate the daily actual evapotranspiration (-Etr) to local and regional scale, using Landsat 8 images (- OLI / TIRS), and additional data collected from a weather station, applying the Surface Energy Balance Algorithm for Land algorithm (- SEBAL). The study area is located in the west of Paraná, in Salto do Lontra County, consisting of irrigated agricultural area, native vegetation and urban area. It was used orbit image / site 223/78 in Julian days 336 2013 and 19, 35, 131 and 195 in 2014. The daily ETr was estimated from the latent heat flux density (LE), obtained from the equation residue of the energy balance. The algorithm consists of several steps which include radiometric calibration, the reflectance calculation, the surface albedo, vegetation index (NDVI, SAVI, and leaf area index - LAI), and emissivity, which are obtained from data from the sensor reflective bands orbital, with the surface temperature estimated from the thermal band. The results showed that the algorithm estimated the components of the energy balance, with higher values than the results generally obtained from previous studies. Concerning to the estimated Etr, there was good agreement between estimates obtained by SEBAL and by the Penman Monteith FAO 56 model, validating the algorithm. The errors between the models were less than or equal to 1.00 mm day-1, results similar to those found in the literature. / A estimativa da evapotranspiração é fator chave no manejo hídrico sustentável em agricultura irrigada, a real necessidade hídrica da cultura de forma objetiva, sem gerar desperdício de energia e água pelo excesso de irrigação e sem comprometer a produção pelo déficit da mesma. Neste sentido, o estudo teve por objetivo estimar a evapotranspiração real diária-ETr, para escala local e regional, utilizando imagens Landsat 8 - OLI/TIRS e dados complementares coletados de uma estação meteorológica, aplicando-se o algoritmo Surface Energy Balance Algorithm for Land - SEBAL . A área do estudo fica localizada no oeste paranaense no município de Salto do Lontra, composta por áreas agrícolas irrigadas e de sequeiro, vegetação nativa e parte urbana. Foi utilizada imagem da órbita/ponto 223/78, nos dias juliano 336 de 2013 e 19, 35, 131 e 195 de 2014. A ETr diária foi estimada a partir da densidade de fluxo de calor latente (LE), obtida do resíduo da equação do balanço de energia. O algoritmo é constituído de várias etapas que incluem calibração radiométrica, cálculo da reflectância, albedo da superfície, índices de vegetação (NDVI, SAVI e índice de área foliar - IAF) e emissividade, sendo estes obtidos a partir de dados das bandas reflectivas do sensor orbital, com a temperatura da superfície estimada a partir da banda termal. Os resultados mostraram que o algoritmo estimou os componentes do balanço de energia, com valores geralmente superiores aos resultados de outros estudos. Quanto à Etr estimada, houve boa concordância entre estimativas obtidas pelo SEBAL e o modelo Penman Monteith FAO 56, validando o algoritmo. Os erros entre os modelos foram iguais ou menores a 1,00 mm dia-1, resultados semelhantes ao encontrado em literatura.
142

Demanda de energia no sistema de produção do pinhão-manso (Jatropha curcas L.) irrigado / Energy input in the production systems of physic nut (Jatropha curcas L) with irrigation

Adriano Valentim Diotto 04 March 2013 (has links)
Impulsionados pelo crescente aumento no consumo de energia e pela pressão às fontes de combustíveis fósseis causada por este aumento, vem crescendo também o interesse por culturas bioenergéticas, buscando substituir, pelo menos em parte, a matriz energética mundial por uma mais sustentável. Dentre as várias opções de oleaginosas disponíveis, tem se apresentado o pinhão-manso (Jatropha curcas L.) como uma planta promissora na produção de biocombustíveis, apesar da baixa disponibilidade de informação sobre esta planta como cultura comercial. Juntamente com esse aumento de interesse nas culturas destinadas a produção de energia, vem aumentando também, o interesse em métodos de análises multicritérios, que seja capaz de apresentar indicativos não só econômicos, mas também de sustentabilidade. Neste contexto, a análise dos fluxos de energia vem sendo muito utilizado para avaliar e comparar diferentes sistemas de produção, quanto ao seu balanço de energia, ou seja, a entrada e saída de energia de um sistema. Realizou-se, portanto, um estudo dos componentes de produção da cultura do pinhão-manso, em seis áreas de produção no estado de São Paulo, onde se determinou a demanda de energia do sistema de produção na condição de sequeiro, e o efeito da inclusão da irrigação via gotejamento e pivô central neste sistema. Na condição de sequeiro, o ponto de equilíbrio entre a incorporação e produção de energia, foi atingido com as produtividades de 1,5 Mg ha-1 ano-1, sem considerar o aproveitamento dos resíduos e 1,3 Mg ha-1 ano-1 se estes forem aproveitados na cogeração. O fator que mais influenciou a incorporação de energia foi a utilização intensiva de insumos como fertilizantes e agroquímicos para controle de pragas e doenças, representando cerca de 65% do total de energia incorporada no sistema de produção de sequeiro. Para a condição de irrigação avaliada, as produtividades mínimas para se iniciar a viabilidade energética foram de 4,27 e 3,60 Mg ha-1 ano-1 respectivamente, para irrigação via pivô central e gotejamento, sem o aproveitamento dos resíduos na cogeração de energia e de 3,88 e 3,27 Mg ha-1 ano-1 quando se considera os resíduos na avaliação. O consumo direto de energia na pressurização do sistema foi o fator de maior influência na incorporação total do sistema de produção irrigado, representando em média 55%. / The increase in the energy consumption and the pressure on the fossil fuel sources have increased the interest in the bioenergy crops, in order to have more sustainable options in the world energy matrix. Among the oilseeds available, Jatropha curcas L. is taken as a promising oil provider to biofuel production. As the interest in bioenergy crops increases, the interest in advanced analysis methods also increases, being able to evaluate the production systems not only economically, but also regarding sustainability. In this context, the analysis of energy flows has been widely used to evaluate and to compare different production systems, determining its input and output energy flows. A study about the inputs required to produce Jatropha in six areas in the state of São Paulo was done. It was determined the energy demand of the production system in dryland condition, and also the effect of drip and center pivot irrigation. In dryland conditions, the feasibility breakeven point between input and output was achieved with yields of 1.5 Mg ha-1 yr-1, without waste recovery and of 1.3 Mg ha-1 yr-1 if wastes are utilized in cogeneration. The factor that most influenced the energy embodiment was the intensive use of inputs such as fertilizers and pesticides, which accounted about 65% of the total embodied energy in the dryland systems. With irrigation, minimum yields to achieve the energy feasibility were 4.27 and 3.60 Mg ha-1 yr-1 respectively, for center pivot and drip, without using wastes in the energy cogeneration and 3.88 and 3.27 Mg ha-1 yr-1 when considering wastes in the evaluation. The direct energy consumption in the pressurization system was the most important factor in the irrigated production system, representing 55% on average.
143

Evapotranspiração do capim tanzânia (Panicum maximum Jacq.) e grama batatais (Paspalum notatum flugge) utilizando o método do balanço de energia e lisímetro de pesagem. / Evapotranspiration of guinea grass (panicum maximum jacq) and bahia grass (paspalum notatum flugge) using energy balance method and weighing lysimeter.

Leonardo Duarte Batista da Silva 08 April 2003 (has links)
A irrigação de pastagens no Brasil apresentou um crescimento acentuado nos últimos anos, porém devido a ausência de pesquisas sobre a aplicação de água em pastagens, o manejo da irrigação não vem sendo realizado de maneira racional. Os objetivos deste trabalho foram avaliar as relações entre a irradiância solar global e a radiação líquida sobre superfícies vegetadas com capim tânzania (Panicum maximum Jacq.) e com grama batatais (Paspalum notatum flugge); determinar a evapotranspiração do capim tânzania, por meio das medidas de lisímetro de pesagem; aplicar o método do balanço de energia para a estimativa da evapotranspiração do capim tânzania, por meio de um sistema automático de razão de Bowen; e comparar os valores de evapotranspiração do capim tanzânia, medidos em lisímetro de pesagem com os estimados pelo balanço de energia por meio de um sistema automático de razão de Bowen. O experimento foi conduzido em Piracicaba, estado de São Paulo. Por meio de um lisímetro de pesagem e um sistema automático de razão de Bowen foram obtidos valores de evapotranspiração do capim tanzânia (ETc). Também foram obtidos dados de irradiância solar global (Qg) e radiação líquida (Rn) sobre grama batatais e capim tanzânia. Os dados foram coletados diariamente e analisados, estatisticamente, mediante análise de regressão. Os modelos de regressão linear de estimativa da radiação líquida encontrados foram Rn = 0,5418.Qg (r 2 = 0,9297) para uma superfície gramada e Rn = 0,5613.Qg (r 2 = 0,8719) para uma superfície vegetada pelo capim tanzânia. A evapotranspiração média do capim tanzânia foi de 4,13 mm.d -1 , segundo o balanço de energia e 4,34 mm.d -1 , obtido pelo lisímetro de pesagem. Com base nos resultados, concluiu-se que o valores de evapotranspiração diários e horários do capim tanzânia medidos pelo sistema automático de razão de Bowen, foram afetados pelo efeito advectivo e pela precipitação, mas apesar disso houve uma razoável correlação com as medidas feitas em lisímetro de pesagem; e o estabelecimento das relações apresentadas neste trabalho mostra que os saldos de radiação em superfície gramada, assim como no capim tanzânia, podem ser estimados satisfatoriamente a partir da irradiância solar global, tendo a necessidade de se considerar suas variações sazonais. / Pasture irrigation presented a large growth in Brazil in recent years. However, the lack of research on pasture water use has led to inefficient irrigation management practices. The objectives of this work were: to evaluate the relationships between global solar irradiance and net radiation on surfaces covered with Guinea grass (Panicum maximum Jacq.) and Bahia grass (Paspalum notatum flugge); to determine the evapotranspiration of Guinea grass through weighing lysimeter measurements; to apply the energy balance method to estimate the evapotranspiration of Guinea grass by means of an automated Bowen ratio system; and finally to compare the evapotranspiration of Guinea grass measured by a weighing lysimeter versus the evapotranspiration estimated by the automated Bowen ratio energy balance system.. Evapotranspiration (ETc) was obtained for Guinea grass by means of a weighing lysimeter and an automated Bowen ratio system. Global solar irradiance (Qg) and the net radiation (Rn) over Bahia grass and Guinea grass were also obtained. The data were collected daily and statistically analyzed through regression analysis. The linear regression models for Rn estimates were Rn = 0,5418.Qg (r 2 = 0,9297) for a Bahia grass surface and Rn = 0,5613.Qg (r 2 = 0,8719) for a surface covered with Guinea grass. Guinea grass average evapotranspiration was 4.13 mm.day -1 by the energy balance method and 4.34 mm.day -1 as measured by the weighing lysimeter. The results led to the conclusion that the daily and hourly evapotranspiration values of Guinea grass obtained by the Bowen ratio automated system, were affected by the advection and by precipitation. Despite that, it was possible to obtain a correlation between the Bowen ratio evapotranspiration and measurements with the weighing lysimeter. The results show that the net radiation over Bahia grass and Guinea grass can satisfactorily be estimated from the global solar irradiance as long as seasonal variations are taken into account.
144

Etude des interactions entre la prédisposition aux mammites et le statut énergétique en début de lactation / A study of the interactions between predisposition to mastitis and energy status during early lactation

Bouvier-Muller, Juliette 15 September 2017 (has links)
Les infections intra-mammaires (IMI) responsables de mammites, sont une cause importante de maladie, de mortalité et de pertes de production chez les ruminants laitiers. Le péri-partum est une période où la fréquence des mammites est significativement plus élevée. Parmi les facteurs de risques, le déficit énergétique, fréquent au début de la lactation, est souvent évoqué. Cependant, les bases mécanistiques de l’éventuelle relation entre IMIs et déficit énergétique sont encore peu comprises. L’objectif de ma thèse était ainsi d’évaluer la relation éventuelle entre le déficit énergétique et la prédisposition aux mammites en utilisant la brebis laitière comme modèle. Mes travaux ont montré que les brebis génétiquement prédisposées aux mammites ont également une sensibilité accrue au déficit énergétique et à la cétose. / Intramammary infections and mastitis are a leading cause of diseases, death and production losses in dairy ruminants. Increased susceptibility to mastitis during the peripartal period has been yet widely documented. Negative energy balance is frequent in early lactation and considered as a known risk factor for mastitis. The relationship between energy balance and mastitis susceptibility however remained unclear and poorly described. The aim of my thesis was to examine the relation between a negative energy balance and susceptibility to mastitis in dairy ewes. In particular, my research works showed an enhanced susceptibility to energy restriction in mastitis-susceptible ewes.
145

Energibalans av två glödgningsugnar inom ett integrerat stålverk

Färnström, Dennis January 2017 (has links)
Av den globala energianvändningen så upptar stålindustrin hela 5 % och sett till CO2 – utsläppen som orsakats av mänskliga faktorer så upptar stålindustrin hela 7 %. Stålindustrin är en energikrävande industri och därför är det viktigt att se över dess energianvändning för en nutida och framtida hållbarhet.  Ugnar är en av de bidragande faktorerna till den höga energianvändningen och de drivs på icke förnybara bränslen, därför är studier kring detta av hög relevans. Moderna tekniker gällande ugnar i dagens läge riktar sig mycket åt förbränningstekniken, d.v.s. förbränningen av bränslet som ugnarna drivs på. Oxyfuel-tekniken innebär att bränslet förbränns med ren syrgas istället för luft, vilket i huvudsakligt syfte är för att höja förbränningsverkningsgraden. Att använda brännare som kan återvinna rökgaser är också en modern teknik för energieffektiv ugnsdrift.  Outokumpu är ett världsledande företag inom tillverkningen av rostfritt stål och anläggningen i Avesta är ett integrerat verk, det betyder att ståltillverkningen i Avesta omfattar hela processen från råmaterial och skrot till färdig produkt. Anläggningen består av tre huvudsakliga verk som kallas stålverket, varmbandsverket och slutligen Linje 76 & Z-High vilket är avdelningen som dessa två glödgningsugnar befinner sig.  Det huvudsakliga syftet med denna rapport är att uppvisa en energibalans av två glödgningsugnar inom Outokumpus anläggning i Avesta, avgränsningarna är också tydliga då energibalansen drar sig ifrån den första ugnens inlopp till den andra ugnens utlopp. Och det är den termiska energieffektiviteten som har studerats, d.v.s. hur mycket energi man får ut av den olja som sätts in. Framtagandet av data har genomförts med hjälp av historiska data gällande ugnarnas drift under ett tidsspann på 3 månader tillbaka i tiden, även manuella temperaturmätningar har genomförts.  En verkningsgrad har tagits fram för varje ugn och ugnarna tillsammans, verkningsgraderna har beräknats genom att väga förhållandet mellan hur mycket energi som det glödgade materialet har tagit upp, med hur mycket olja som har använts under samma tidsspann.   De huvudsakliga resultaten till denna studie tyder sig på att ugnarna är effektiva till att värma stålet och har relativt små transmissionsförluster från ugnarnas omslutande areor. Däremot så finns potential att kunna återvinna mer värme ifrån rökgaser i avgaspannan. / The steel industry occupies the whole 7 % of the global carbon dioxide emissions caused by human factors and 5 % of the global energy usage. The steel industry is an energy intense industry and it’s therefore important to analyze its energy use for its future sustainability. Furnaces are driven on non-renewable fuels and are one of the devoting components to the high energy consumption, so studies of this are of high relevance.  Regarding modern techniques of furnaces in today’s mode are much concentrated on the combustion, which means the combustion of the fuel that supplies the furnaces with heat.  Oxy-fuel technology means that the fuel is combusted with pure oxygen instead of air, and its purpose is to increase the combustion efficiency. A second modern technology is the usage of burners that are able to recycle flue gases as an increase of energy efficiency.  Outokumpu is a world leading company in the manufacture of stainless steel and the plant in Avesta is an integrated steel mill, which means the steel production cover the entire process from scrap and raw material to finished product. The plant consists of three main works called the steel mill, hot rolling mill and KBR L76 which is the department for these annealing furnaces.  The main objective of this report is to present an energy balance of two annealing furnaces at the Outokumpu plant in Avesta. The boundary of the study is clear, the energy balance will take part from the inlet of the first furnace to the outlet of the second one. It’s the thermal energy efficiency that has been studied, that is to say how much energy you get from the fuel that is added. Information has been collected using historical data on the operation of the furnaces during a three month period of time, also manual temperature measurements has been carried out.  By calculations an efficiency has been developed for each furnace and the furnaces together. This has been carried out by weighing the proportion of the amount of heat that all material have accumulated, with the amount of oil used during the same time.  The results of this study mainly indicate that the furnaces are effective in heating the steel, and its heat losses from the surrounding areas are small. On the other hand, there is potential for recycling more heat regarding the use of flue gases in the exhaust-boiler.
146

Effect of a high fat diet on a mouse model of Alzheimer's disease

Knight, Elysse January 2011 (has links)
Alzheimer's disease (AD) is a progressive neurodegenerative disorder, characterised by deficits in language, behaviour and memory. Increasing evidence suggests that mid-life obesity and a diet high in fat are risk factors for AD. In contrast, life-threatening weight loss occurs and worsens as the disease progresses, despite adequate or increased food intake. A greater understanding of energy balance in AD may therefore uncover novel targets for therapy. The aim of this thesis was to test the hypothesis that 3xTgAD mice display altered energy balance and that experimental changes to this balance will alter cognition. To address this hypothesis, three key objectives were set up; to characterise the energy balance profile, characterise behaviour and memory, and evaluate the response to an high fat (HF) diet in a triple transgenic (3xTgAD) model, an experimental mouse model of AD. Energy balance was characterised in non-transgenic (Non-Tg) control and 3xTgAD mice, demonstrating altered body weight, food intake and metabolic rate in the 3xTgAD mouse model of AD. At 2-month of age male 3xTgAD mice displayed greater food intake and body weight, but no difference in metabolic rate, whereas from 12 months of age 3xTgAD mice weighed less, despite eating more, and had a higher metabolic rate than Non-Tg control mice. This provides evidence that there is a shift towards a hypermetabolic state from 12 months of age in 3xTgAD mice, which may represent a key stage in advancement of the disease process. Behaviour and memory were characterised in Non-Tg control and 3xTgAD mice in a battery of tests at different ages. 3xTgAD mice showed changes in open-field activity/anxiety from 3 months of age. Memory impairments were first detected in 3xTgAD mice at 3 months of age as deficits in odour recognition memory, mirroring early impairments seen in AD patients. Deficits in spatial memory were then observed in both the Y-maze spontaneous alternation and Morris water maze tests from 5 months of age. Finally, deficits in non-spatial visual object memory were observed in 3xTgAD mice in the novel object recognition test at 8 months of age. Energy balance, behaviour and memory were assessed in Non-Tg control and 3xTgAD mice in response to an HF diet. Non-Tg control and 3xTgAD mice displayed similar energy balance profiles in response to an HF diet. The HF diet was found to worsen memory in Non-Tg mice in odour recognition at 3-4 and 7-8 months of age, in the Morris water maze at 7-8 months of age and in novel object recognition and spontaneous alternation at 11-12 and 15-16 months of age. Similarly, the HF diet worsened memory in 3xTgAD mice in odour discrimination at 3-4 and 7-8 months of age, the Morris water maze at 7-8 and 11-12 months of age, and in spontaneous alternation at 15-16 months of age. As an HF diet induced memory impairments, in both Non-Tg control and 3xTgAD mice, it suggests that diet-induced deficits may therefore, not be specific to AD, but rather to cognition in general. Overall, these data demonstrate that 3xTgAD mice show AD-like age-dependent changes in energy balance, behaviour and memory. Furthermore, an HF diet produced impairments in memory in 3xTgAD mice, but these effects were not specific to AD, as an HF diet also led to deficits in control animals. These data support a role for energy balance in the progression of AD, although the underlying mechanisms remain poorly understood. 3xTgAD mice may therefore represent a good model to examine energy balance during AD and to evaluate targets for future therapies.
147

Undersökning av biogaspotential i rötat avloppsslam

Larsson, Henric, Sjödal, Madeleine January 2011 (has links)
Avloppsreningsverket Sundet i Växjö har en rötningsanläggning som producerar biogas. Anläggningen består idag av två rötkammare och en maskin för avvattning som substratet går igenom efter rötningen. Substratet som används i rötningsprocessen är avloppsslam från Växjö. Planer finns på att utöka processen med en tredje reaktor i vilken det rötade slammet ska återrötas. Detta för att få ut mer biogas ur slammet. Det rötade slammet från reaktor 1 och 2 planeras genomgå tre förbehandlingssteg i form av fasseparering, sönderdelning och hygienisering innan det går till den tänkta reaktor 3. I arbetet genomförs ett rötningsförsök av rötat slam från Sundet med hjälp av satsvisa reaktorer som ska representera den planerade tredje reaktorn. Syftet med arbetet är därmed att undersöka hur mycket mer biogas det går att utvinna genom en andra rötningsprocess. Beräkningar på hur mycket energi det kommer gå åt i förbehandlingsstegen och hur mycket extra energi som går att utvinna i form av biogas från rötningsförsöket utfördes i arbetet. Resultaten visar att det går att utvinna mer metanrik biogas ur slammet och att förbehandlingsstegen fasseparering och sönderdelning kostar små mängder energi i förhållande till hur mycket extra energi som den extra biogasen ger. Hygieniseringen beräknas kosta förhållandevis mycket energi jämfört med den energin från den producerade biogasen. / The municipal waste treatment plant Sundet in Växjö currently has a digestion plant producing biogas. The facility consists of two digesters and a machine that dewaters the sludge after the reactors. The substrate that is used in the reactors consists of sewage sludge from Växjö. There are plans to expand the process with a third reactor in which the digested sludge will be digested a second time in order to extract more biogas. The digested sludge from reactor 1 and 2 is planned to undergo three pretreatment steps in the shape of phase separation, decomposition and sanitation before it reaches reactor 3. In the thesis a digestion process is carried out with digested sludge from Sundet in batch reactors that represents the planned third reactor. The purpose is to analyze how much extra biogas that can be extracted with a second digestion process. Calculations of how much energy that is necessary for the pretreatment stages and how much extra energy that can be extracted in the shape of biogas from the digestion process was made in the thesis. The results from the experiments shows that it is possible extract more methane rich gas from the sludge and that the pre treatment stages phase separation and decomposition use small amounts of energy compared to how much energy the extra gas gives. The sanitation process is estimated to cost quite a lot of energy compared to the energy extracted through biogas.
148

Observing and modeling climate controls and feedbacks on vegetation phenology at local-to-continental scales

Moon, Minkyu 13 October 2020 (has links)
Vegetation phenology controls seasonal variation in ecosystem processes and exerts important controls on land-atmosphere exchanges of carbon, water, and energy. However, the ecological processes and interactions between climate and vegetation that control phenology and associated feedbacks to the atmosphere are not fully understood. In this dissertation, I use remote sensing in combination with climate and ecological data to improve understanding of biophysical controls and feedbacks between vegetation phenology and the atmosphere in temperate forest ecosystems of North America. In the first part of this dissertation, I evaluate the agreement and characterize the similarities and differences between land surface phenology products from two remote sensing instruments (MODIS and VIIRS) that are designed to provide long-term continuity of land surface phenology measurements at global scale. Results from this analysis indicate that the VIIRS land surface phenology product provides excellent continuity with the MODIS record despite subtle differences between each instrument and the algorithms used to generate each product. In the second part of this dissertation, a state-space Bayesian modeling framework is applied to seventeen years of MODIS and daily weather data to improve understanding of what controls the timing of springtime phenology in deciduous forests of temperate and boreal North America. Results show that photoperiod is more important in warmer regions than in colder regions, which contradicts a widely held hypothesis that photoperiod provides a key safety mechanism preventing early leaf-out during springtime. In the final part of this dissertation, I use a physically-based attribution method to quantify the relative importance of covarying surface biophysical and atmospheric variables in modifying the surface energy balance during springtime. Results show that the widely observed decrease in the Bowen ratio that occurs with leaf emergence is not solely attributable to changes in surface resistance caused by increasing leaf area during spring. Rather, observed changes in the Bowen ratio reflect the combined effects of changes in surface properties and atmospheric conditions. The results from this dissertation provide an improved foundation for long-term studies focused on observing and modeling springtime vegetation phenology and associated feedbacks to the atmosphere in deciduous forest ecosystems at local-to-continental scales.
149

Využití odpadního tepla z rektifikace / Utilization of waste heat from rectification

Frank, Vojtěch January 2018 (has links)
The purpose of the thesis is to draw up a model of the energy and material balance using technical and technological analysis of the current state of production of waste heat in the process of distillation. Using these results, subsequently evaluate the energy potential of individual streams and propose optimal energy savings using waste heat. Emphasis is placed on the modelling of the process and the various proposed savings options. The result is also an evaluation of the potential of the proposed savings based on the results of the calculation.
150

Výroba vodíku z biomasy II / Hydrogen Production from Biomass II

Matějka, Pavel January 2011 (has links)
This master thesis continues the master thesis Výroba vodíku z biomasy. In that work were performed first experiments of hydrogen production from beer less by dark fermentation. Further experiments will continue based on previous experiments. For the energy balance were used results from [1] and data obtained from literature searches, because the results of the experiments were not entirely satisfactory. Energy balance was calculated for a laboratory fermenter to evaluate the efficiency of energy obtainable from the hydrogen produced by fermentation in a dark laboratory conditions. It was compared the yield given in [1] and yield derived from a literature review. The conclusion presents recommendations for further research.

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