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Migliavacca, Alencar. "Balanço de massa, energia e exergia na produção intensiva de frangos de corte." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-06122017-090731/.
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A produção brasileira de frangos de corte evidenciou-se com o sistema de produção integrada, ao elevar a eficiência e a qualidade na conversão de proteína animal. Contudo, devido à rápida evolução tecnológica com crescente demanda energética e a diversificação dos sistemas de produção em diferentes microclimas, elucidar os processos de conversão de massa e energia tornou-se uma tarefa desafiadora neste sistema de produção. Constantemente, pesquisadores, produtores e agroindústria buscam processos mais rentáveis, reduzindo a demanda em mão de obra e o impacto ambiental. No entanto, nunca foi feita uma avaliação integrada do sistema produtivo de frangos de corte, considerando-se os aspectos quantitativos, energéticos e ambientais. Deste modo, o objetivo deste trabalho é promover um detalhado balanço de massa e energia, além de avaliar por meio da análise exergética, a qualidade das conversões de energia no processo produtivo de frangos de corte. Com o levantamento de insumos, produtos e rejeitos diretos, vinculados ao ciclo de produção, foram quantificadas as vazões mássicas para os diferentes processos do ciclo e, aplicando-se a avaliação exergética, obteve-se um diagnóstico completo da quantidade e qualidade energética envolvidas. Considerando o cenário adotado, em termos mássicos, as maiores demandas identificadas para os insumos foram a água (69,2%) e a ração (24,9%). Na saída do processo, os Gases de Efeito Estufa (GEE)/particulados extraídos através da ventilação (39,4%), os gases de combustão da lenha (25,6%) e a cama (14,2%) formam os principais rejeitos. A massa de frangos representa 20% das saídas. Foi identificado que a relação entre o consumo de água e ração é função da temperatura. Em termos energéticos, as maiores contribuições identificadas para os insumos foram a ração (77,7%) acompanhada do material absorvente (9,7%) e da lenha (9,6%). Na saída do processo lideram as energias associadas aos frangos (33,2%) e da cama gerada (32,1%). O rendimento energético obtido para galpões convencionais foi de 27%. Os processos que mais destroem exergia dentro do ciclo produtivo são a formação da cama de frangos a partir das excretas (51,5% em convencionais e 48,2% em climatizados) e a combustão da lenha para aquecimento (21,9% em convencionais e 20,5% em climatizados). Além disso, foi estimado o rendimento de Segunda Lei para o ciclo próximo de 26%. Foram introduzidos os índices energético e exergético de produção permitindo a comparação entre diferentes sistemas. Como principal resíduo, a cama de frangos gerada no ciclo, quando reutilizada como insumo para aquecimento do próprio aviário na forma de briquetes, pode elevar as eficiências. Comparando-se as demandas médias para as duas formas de aquecimento, foi constatado que o uso do GLP é mais favorável ao ambiente se comparado à lenha, devido à forma direta de transferência de calor aos frangos. É aconselhável, em dias quentes, elevar a velocidade do ar, utilizando o resfriamento evaporativo somente em casos de elevada temperatura ambiente, pois a introdução de água eleva a exergia dissipada no ciclo.Brazilian production of broilers has been highlighted with the implantation of the integrated production system, which improved the efficiency and quality in animal protein conversion. However, due to the rapid technological evolution with the increasing energy demand and the diversification of production systems in different microclimates, elucidating mass and energy conversion processes has become a challenging task regarding this production system. Constantly, researchers, producers and agribusiness look for more profitable processes, reducing the labour demand and environmental impact. However, an integrated evaluation of the productive system of broilers, considering the quantitative, energy and environmental aspects has never been carried out. Thus, this study aims at promoting a detailed mass and energy balance and to evaluate the quality of the energy conversions in the productive process of broilers by means of exergy analysis. With the survey of inputs, products and direct wastes, linked to the production cycle, the mass flow rates for the different processes of the cycle were quantified and a complete diagnosis of the quantity and quality energetic involved was obtained applying the exergy evaluation. Considering the scenario adopted, in mass terms, the greatest demands identified for the inputs were water (69.2%) and feed (24.9%). At the exit of the process, the greenhouse gases/dust extracted through ventilation (39.4%), the firewood combustion gases (25.6%) and the litter poultry generated (14.2%) are the main outputs. The broilers mass was quantified in 20%. The relation between water and feed consumption has shown to be the temperature. Regarding energy, the largest contribution identified for the inputs was feed (77.7%) followed by the absorbent (9.7%) and firewood (9.6%). At the exit of the process lead the energy associated with the broilers (33.2%) and the poultry litter generated (32.1%). The energy performance obtained for conventional shed was 27%. The processes of the largest exergy destroyed within the productive cycle are the litter poultry converted from excreta (51.5% in conventional and 48.2% in air conditioning) and the combustion of wood for heating (21.9% in conventional and 20.5% in air conditioning). In addition, the second law performance for the cycle was estimated in about 26%. The energy and exergy production index was introduced allowing for the comparison among different systems. As the main residue, the litter poultry generated in the cycle when reused as an input for heating the aviary itself in the form of briquettes, can increase these efficiencies. The use of LPG is more environmentally friendly compared to wood, considering the average demands for the too forms of heating, due to the direct form of heat transfer to the broilers. It is advisable, on hot days, to raise the air speed using the evaporative cooling only in cases of high ambient temperature, as the introduction of water raises the exergy dissipated in the cycle.
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Phuthi, Thabisani Nigel. "Steelmaking with the ESS furnace : a model-based metallurgical analysis." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/75934.
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This research project investigated the option of steelmaking with the ESS furnace by using computational
modelling to estimate steady state decarburisation rates. It focused on understanding metallurgical
phenomena that would dictate refining rates of molten pig iron with iron ore. The results obtained
are aimed at designers and potential users of the furnace technology to improve their understanding of
the expected steady-state process behaviour. A mass-and-energy-balance model with a decarburisation
sub-model was developed to estimate feed material requirements for steady state operation.
Modelling and simulation results suggest that it may not be possible to produce steel under the
conditions proposed. However, the furnace still holds potential if ideal operational conditions are understood
and applied.
Modelling also gave insight into which areas areas of concern, such as bubble formation in the furnace’s
channel induction heaters, and necessity for a well designed refractory lining to contain heat and allow the
process to operate at a stable condition under the conditions proposed.
Keywords: ESS furnace, steelmaking, metallurgical analysis, modelling, mass and energy balance,
decarburisation kineticsDissertation (MEng)--University of Pretoria, 2020.
Materials Science and Metallurgical Engineering
MEng
Unrestricted
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Rafiee, Nima. "Process design and energy efficiency analysis of an oil and gas processing plant." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Abstract
The objective of this thesis is process design to prepare a heat and mass balance and associated equipment list that will process untreated reservoir fluids to allow export of saleable gas and oil in an oil and gas processing plant. Gas will be exported to an existing pipeline, oil to a nearby shuttle tanker. By energy efficiency analysis, some energy saving opportunities has been found such as heat integration, replacing control valves with expanders and improving pumps and compressors adiabatic efficiency and then the amount of power recovered through these opportunities have been calculated. After that by considering water added to the feed stream, gas dehydration unit is needed for gas drying. In this reason, a design of TEG dehydration unit has been done and compared with the energy consumption by molecular sieve dehydration unit. Comparison shows that molecular sieve dehydration unit consumes energy about two times more than TEG dehydration unit does. Furthermore, by designing fractionation unit and introducing dividing wall column, consumption of energy decreased about 33% in comparison with conventional columns. In the final part, some energy efficiency opportunities of pumps and compressors, which are the most energy consuming equipment in the oil and gas industries have been introduced. Moreover, the means of power generation for oil and gas plants have been studied. Most plants use gas turbine for power generation and introduce means of increasing gas turbine efficiency and its performance. In the final part some methods for recovery the low-grade heat, variable speed drive which shows significant energy saving, power recovery turbines and reducing friction losses through pipes have been defined.
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Grimaldi, David Andres. "Dissolved Gases and a Carbon Dioxide Balance from the San Vicente Geothermal Fieldin El Salvador, Central America." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1615276127141058.
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Claverie, Etienne. "Modélisation de la température du sol avec un bilan d’énergie, application à la prédiction de l’émergence du maïs (Zea mais)." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC028/document.
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La croissance en début de cycle des grandes cultures est principalement influencée par la température et la teneur en eau du sol. Nous avons développé un modèle capable de prédire ces variables grâce à l’utilisation de données climatiques largement disponibles. Des analyses de la sensibilité du modèle nous ont permis d’identifier les composants qui contribuent à son incertitude. Après calibration, une erreur moyenne relative de moins de 10 % est constatée pour la température et la teneur en eau à 30 cm de profondeur.Dans des conditions de semis standard en Suisse, l’émergence du maïs a été mieux prédite en utilisant notre température de sol simulée plutôt que la température de l’air, plus couramment utilisée. Ce travail est une application d’un modèle biophysique complexe à un problème agronomique. Les résultats participeront à l’optimisation de l’effort de sélection des variétés tolérantes au froid. Deux pistes de recherche peuvent être considérées pour des futurs travaux: une meilleure modélisation de l’évaporation et une décomposition de l’émergenceThe beginning of crop growth is influenced by soil temperature and water content near the surface. We have developed a model that predicts the local temperature and water content surrounding the seed using easily available meteorological data. Our global sensitivity analysis helped us identify the components of the model with the largest contribution to the output uncertainty. After calibration, the model showed less than 10 % relative error for temperature and water content at 30 cm. In standard sowing conditions in north-western Switzerland, the emergence was better predicted when using our simulated seed bed temperature than air temperature, the classical proxy variable. Combining the emergence model with soil temperature simulation, an accurate prediction of emergence was achieved. This work is an example of applying complex biophysics model for understanding an agronomic problem. The results of this work will participate in optimising breeding efforts for cold-tolerant crop varieties. Future investigations should consider a finer modelling of processes for evaporation and emergence
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Ranasinghe, Milinda A. "Modelling the mass and energy balance in a compost biofilter." Thesis, University of Canterbury. Chemical and Process Engineering, 2003. http://hdl.handle.net/10092/7492.
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A biofilter model was developed using the mass and energy balances in the gas, liquid and solid phases, which related the biofilter performance to the water content in the packing material. A key simplification of the model was that the concentration gradients in the biofilm were neglected by treating the biofilm/water layer as well mixed and in instantaneous equilibrium with the gas phase. Thus, the biofilm geometry and density parameters were lumped into the overall degradation term. The solid phase was treated as a separate well-mixed layer but solid phase dynamics were accounted for by using the Linear Driving Force (LDF) mass transfer model. The mixed form of Richard's equation together with experimentally obtained unsaturated hydraulic conductivity and water retention curves for compost were used in the continuity equation for the liquid water phase. This approach produced a model where all parameters could be potentially independently determined.
The model was used to test suitable irrigation strategies for a biofilter system degrading toluene subject to different operational conditions. Under this approach both unidirectional and directionally switched biofilter configurations were tested for a 1 m long column. The unidirectional schemes incorporated both open and closed loop irrigation schemes, where the latter was based on commonly used on-line moisture measurement techniques. All schemes were evaluated based on the removal efficiency achieved and the leachate produced. Simulations under a constant irrigation rate of 5.46x 10⁻²g/m²s for a mass loading range of 13-60 g/m³h yielded removals ranging from 88%-26%. An order of magnitude drop in leachate under the high loading indicated severe drying in the system. For a high mass loading of 60 g/m³h, directional switching with a one-day frequency yielded a removal of 33% Vs 26% in an up flow scheme with similar leachate rates. Feedback control on water content provided an improved removal of 84% as compared to 73% under constant irrigation, when both schemes were subjected to load and inlet air step disturbances from 13 g/m³h to 62 g/m³h and from 298 K to 283 K respectively. A sensitivity analysis indicated that the model was most sensitive to the relationship between moisture content and degradation, which was also reflected by the high sensitivity of the model to the kinetic parameters in the degradation term.
A novel batch recycle reactor was thus developed to investigate the effect of water content changes on the degradation rate in low water content systems such as biofilters. The reactor tightly controlled the water content of the unsaturated packing material by using the principle of a suction cell. Experimental runs were performed with toluene as the contaminant using unamended compost at a constant temperature of 30°C. Matric potential in the compost was maintained at values between -6 and -36 cm H₂O and the gas phase was monitored by sampling/gas chromatography. A soil water retention curve relating matric potential to gravimetric water content was generated for the compost. Periodic dry weight analyses of reactor samples together with the water retention curve verified moisture content control. Degradation results demonstrated a biologically limited region followed by a non-linear region at lower concentrations. Elimination capacities were obtained along the wetting and drying curves and changes in the water content affected the removal rates in the linear region ranging from 155 g/m³h to 24 g/m³h over the matric potential range investigated. Repeatability studies indicated that moisture content was the most likely parameter that influenced the changes in performance. Batch scale experiments were also performed using microbially inhibited compost, which provided linear sorption isotherms for toluene on compost at concentrations between 0-1000 ppmv and temperature values of 25°C and 35°C.
The simulation model developed here provides a useful tool to implement and evaluate various operational schemes under different irrigation strategies. This is achieved by way of greater flexibility in incorporating the various schemes into the base model and the comparatively low simulation time to obtain the relevant results.
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Fang, Yuan-Hao, Xingnan Zhang, Chiara Corbari, Marco Mancini, Guo-Yue Niu, and Wenzhi Zeng. "Improving the Xin'anjiang hydrological model based on mass–energy balance." COPERNICUS GESELLSCHAFT MBH, 2017. http://hdl.handle.net/10150/625180.
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Conceptual hydrological models are preferable for real-time flood forecasting, among which the Xin'anjiang (XAJ) model has been widely applied in humid and semi-humid regions of China. Although the relatively simple mass balance scheme ensures a good performance of runoff simulation during flood events, the model still has some defects. Previous studies have confirmed the importance of evapotranspiration (ET) and soil moisture content (SMC) in runoff simulation. In order to add more constraints to the original XAJ model, an energy balance scheme suitable for the XAJ model was developed and coupled with the original mass balance scheme of the XAJ model. The detailed parameterizations of the improved model, XAJ-EB, are presented in the first part of this paper. XAJ-EB employs various meteorological forcing and remote sensing data as input, simulating ET and runoff yield using a more physically based mass–energy balance scheme. In particular, the energy balance is solved by determining the representative equilibrium temperature (RET), which is comparable to land surface temperature (LST). The XAJ-EB was evaluated in the Lushui catchment situated in the middle reach of the Yangtze River basin for the period between 2004 and 2007. Validation using ground-measured runoff data proves that the XAJ-EB is capable of reproducing runoff comparable to the original XAJ model. Additionally, RET simulated by XAJ-EB agreed well with moderate resolution imaging spectroradiometer (MODIS)-retrieved LST, which further confirms that the model is able to simulate the mass–energy balance since LST reflects the interactions among various processes. The validation results prove that the XAJ-EB model has superior performance compared with the XAJ model and also extends its applicability.
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Surowiec, Roman. "Mass energy analysis of processing plasmas." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321132.
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Rodríguez, Sánchez Jonay. "Energy Analysis of an Historical Church, Sjömanskyrkan : Energy balance and efficiency measures." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17174.
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The main topic of this project is to do an energy study of the Mariners’ Church, ‘Sjömanskyrkan’, placed in the Centralplan of Gävle, Sweden. This is an old building built in the late 1800’s by the evangelic-lutheran missionaries and nowadays is used to realize different cultural activities such as concerts, meetings, workshops… Energy is one of the most important points in the actual society. The fact that common energy sources are being depleted and the use of these resources produces a lot of contaminants have brought some many international crisis and conflicts. A big use of oil fuels can influence the government behavior and condition its laws and regulations. Nowadays, the majority of the countries want to reduce their fossil energy sources dependency, e. g. Sweden designed an energy commission in 2005 to make a report on how these uses of petroleum, natural gas and ‘fossil raw materials’ can be reduced until 2020. This project wants to follow this direction, providing some energy savings through the investment and renewal of old public buildings. The aim of this project is to know how much and in which way this building uses the energy, locating its strong and weak points, and point out some different energy efficiency measures to improve the situation. First of all, an energy balance has been realized. In the part of the heat gains the total energy use is 274 MWh / year. On the other hand the energy losses give a quantity of 273 MWh / year. The differences between both are the losses by infiltration, 1MWh / year. Most of this energy is lost because of the transmission, about a 95% of the energy losses. The age of the building and its old materials are the main reason for this out of proportion percentage. That’s why the main efficiency measures are referred to this part. After this first analysis, some efficiency measures have been carried out. The most important are referred to the structural elements like walls, windows, roof and floor. All of these procedures can save 45% of the energy losses. This is evidence that old buildings and this in particular, are really bad insulated and have a lot of heat leakages. Also some behavior recommendations are given, like maintenance works and lightning improvements.
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Huintjes, Eva [Verfasser]. "Energy and mass balance modelling for glaciers on the Tibetan Plateau : extension, validation and application of a coupled snow and energy balance model / Eva Huintjes." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1065848064/34.
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DeBuhr, Christopher Leonard. "Metamorphic petrology and mass balance analysis in the Bugaboo contact aureole." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/NQ49488.pdf.
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Nilsson, Simon. "Influence of fuel mix on mass balance of Cl, S, and K in a long rotary kiln." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-160532.
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Lime is a material with a wide range of applications including land improvement, water treatment as well as the paper-, steel-, and cement industry. Annual worldwide production was estimated at 350 Mt/year for 2016 and 2017 and the production is responsible for a large contribution of the greenhouse gas CO2 to the atmosphere, contributing to global warming. Since there is a need for high temperatures in the production process it is common that fossil fuels are used due to their high energy density and favourable combustion characteristics. Therefore a net emission of CO2 comes from the fuel, but a large amount is also released from the calcination of the raw material, limestone, approximately 1 ton of CO2 is released for every ton of quicklime (CaO) produced. Efforts are being made toward reducing emissions from both the fuel and the limestone. Nordkalk AB, for whom this work has been performed, are aiming to partly replace their use of fossil fuel in their lime kiln in Köping with renewable biomass alternatives. The purpose of this study was to establish a mass balance over the lime kiln in Köping for different limestone and fuel mixes and study the effects they had on mass balance for sulphur, potassium, and chlorine. Five different periods were studied where four of them had fuel mixes consisting of fossil fuels (coal and oil) and in the fifth period olive pomace, a renewable fuel, was added to the fuel mix at 11 % of the net calorific input. It was found that no significant change in product quality occurred and no increase in sulphur and chlorine emissions through the flue gas was detected with this fuel addition. However there were indications from throughput calculations that buildup of corrosive deposits, such as KCl, could be occurring with the addition of olive pomace due to comparatively large input of potassium and chlorine. The increased sulphur input form olive pomace appeared to accumulate in the lime kiln dust mass flow while flue gas emissions remained unchanged. This method of establishing a mass balance is considered to be a good way to understand how different inputs affect the elemental balances over a lime kiln. However the quality of the mass balance is highly dependent on how representative the composition of the mass flows are and how they are acquired.
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Laukkanen, Mikko. "Project Solaris - Mass and balance analysis tool for a solar powered UAV." Thesis, Mälardalen University, School of Innovation, Design and Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-7449.
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Eriksson, Pia. "Meteorological differences between Rabots glaciär and Storglaciären and its impact on ablation." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-121546.
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In the Kebnekaise Massif, Northern Sweden, the west facing glacier, Rabots glaciär, is loosing volume at a significantly higher rate than east facing, Storglaciären. By analyzing data from automatic weather stations situated on the ablation area on the glaciers we investigated the effect of meteorological differences on ablation. There was a difference in micro-climate between Rabots glaciär and Storglaciären. Generally Storglaciären had slightly warmer and drier air, had less or a thinner cloud layer but more precipitation. On both glaciers a glacier wind is dominant but high wind velocities were common especially on Storglaciären indicating a larger influence from the synoptic system. There was a good correlation for temperature and vapor pressure between the glaciers that indicate that both glaciers are strongly affected by the synoptic system. The meteorological parameters have similar effect on the ablation on the glaciers. Temperature, vapor pressure and the turbulent heat fluxes are the only meteorological parameters that suggest a linear affect on ablation. Net shortwave radiation contribute with the greatest amount of energy for ablation but decreased in relative importance as the temperature increased. Shortwave radiation, sensible and latent heat contributed with a total 184Wm-2 on Rabots glaciär and 222Wm-2 on Storglaciären. Rabots glaciär seem to have a significantly greater relative importance of the turbulent heat fluxes than Storglaciären. Although the differences in micro-climate were not great, using the ablation for Storglaciären to estimate ablation on Rabots glaciär would over estimate the ablation with 0.5m w.e..
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Coffey, Michael Peter. "A phenotypic and genetic analysis of energy balance in dairy cows." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/27814.
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In dairy cows, the failure or unwillingness to eat sufficient in early lactation when yield is high leads to a state known as negative energy balance (NEB). In this state, cows mobilise body tissue mostly in the form of body lipid in order to make up the difference in energy available from feed ingested and that required to sustain obligatory requirements, such as maintenance, and milk production. A large NEB is an undesirable state since it is associated with increased disease and reduced fertility. Body lipid content can be predicted from visual assessment of the tailhead of cows using a system known as body condition scoring (BCS). Changes in this score over time can therefore be used to predict body lipid changes. I investigated the feasibility of automating the process of collecting condition score using a digital camera and laser lights. The correlation between CS and shape over the tail-head was 0.55 suggesting that it may be possible in future to include digital images in an automated and integrated dairy farm management system. Using random regression analysis, I analysed changes in milk production, feed intake, liveweight and BCS over one to three lactations and calculated energy balance from these daily predictions. These analyses showed that energy balance can be predicted from body measurements without the need to measure feed intake making it practical to use nationally. Using these techniques enabled the genetic analysis of large volumes of field data to predict daily breeding values for energy balance for 1250 progeny test sires. Substantial genetic variation was found in energy balance profiles. The mean total daughter body energy loss at day 305 of lactation was 779 MJ (SD=224 MJ), equivalent in energy terms to about 189 kg milk. Future selection indices may contain an adjustment for the amount of body energy used to support the milk production of a bulls' daughters leading to a more complete assessment of the utility of a bull. Analysis of data from the Langhill Dairy Research Centre demonstrated that there are differences in the way dairy cows of differing genetic merit for production mobilise body lipid to support lactation and that the amount of concentrate fed also affects the recovery of lost body lipid. Select cows contained about 3200 MJ less energy than control cows at the end of the third lactation and lose and gain body lipid in a cyclical way. Parameters of these curves may be used in future selection indices to allow selection o f genotypes that have profiles of body lipid loss and gain commensurate with high yields and long herd life. This may also be useful in future when selection indices contain more traits and farmers and advisors tailor their management to suit the type of cow. It may also provide guidance on how future selection indices should be developed to incorporate traits such as body lipid, traits that enable the robust cow to thrive over many high yielding lactations.
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BERNARD, Pierre. "Modelling, analysis and optimization of thermal energy balance in anaerobic digestion." Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210187.
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För att bedöma lönsamheten hos en biogasanläggning krävs det insikt om den termiska självkonsumtionen. Detta examensarbete syftar till att ge en heltäckande modell för att beräkna den termiska självkonsumtionen för två olika typer av biogasanläggningar (våt- och torrötning). Beräkningarna omfattar energi för att värma upp råmaterialet, förlorad energi med vattenavdunstning och förluster i de olika tankarna under processer. Särskild uppmärksamhet ägnades åt en dubbelmembran tak. Olika kontroller utfördes för att bedöma modellers giltighet, vars resultat stämde överens ganska väl. Den termiska självkonsumtion av en biogasanläggning är i huvudsak definierad av den värme som behövs för att värma upp råmaterialet och förlusterna från dubbelmembrans tak. För att förbättra den termiska konsumtion av biogasanläggning är det viktigt att fokusera på råvaran initialtemperatur som svarar för en betydande del av värmebehovet. Dessutom uppgick upp till 80% av förlusterna i en kokare (våt biogas anläggning) och 60% av förlusterna i en torr biogas anläggning från dubbelmembrans tak. Takisolering med en 3:e membran för att bryta konvektion har därmed studerats och besparingar i uppvärmning som resultat av denna lösning är lovande.Assessing the profitability of an anaerobic digestion (AD) plant requires knowing its thermal self-consumption. This Master Thesis aims at providing a comprehensive model to calculate the thermal self-consumption of two different types of AD plants: wet (Continuous Stirred Tank Reactors) and dry (Garage-type dry AD). The energy to warm up the feedstock, the energy lost with water evaporation and the losses of the different tanks of the process were considered. A particular attention was paid to the double-membrane roof. Different reality checks were carried out in order to assess the validity of the model, whose results agree reasonably well. The thermal self-consumption of a plant is mainly defined by the heat necessary to warm up the feedstock and by the losses from the double-membrane roof. To improve the thermal performance of AD plants, it is needed to focus on the feedstock initial temperature (storage modes …) which accounts for a significant part of the heat requirements. Furthermore, losses from the double-membrane roof amounts up to 80% of the losses of a digester (wet AD plant) and 60% of the losses of a dry AD plant. Insulating the roof with a 3rd membrane in order to break convection has thus been studied and the savings in heating due to this solution are promising.
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Brunzell, Lena. "Energy Efficient Textile Drying." Licentiate thesis, Karlstad University, Faculty of Technology and Science, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-729.
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Traditionally, textiles were dried outdoors with the wind and the sun enhancing the drying process. Tumble dryers offer a fast and convenient way of drying textiles independent of weather conditions. Tumble dryers, however, consume large amounts of electrical energy. Over 4 million tumble dryers are sold each year in Europe and a considerable amount of energy is used for drying of clothes. Increasing energy costs and the awareness about environmental problems related to a large energy use has increased the demand for dryers with better energy efficiency. The aim with this thesis is to show how to improve the energy efficiency of domestic tumble dryers.
Two types of tumble dryers are available on the market today: the open cycle dryer and the closed cycle dryer. In the open cycle dryer room air is heated and led into the drying drum. The exhaust air leaves the dryer and is often evacuated outside the building. In the closed cycle dryer an internal airflow is recirculated inside the dryer. When the hot air has passed through the drying drum it is led through a heat exchanger where the water vapour is condensed before the air is heated again and led to the drum. The heat exchanger is cooled with room air.
Drying at low temperature has been shown to reduce the specific energy use for an open cycle tumble dryer. In Paper I a correlation between the specific energy use, the drying time and the heat supply was established for a specific load by using the exhaust air temperature. It was shown that the total drying time and specific energy use could be predicted from data during the first hour of the process. This result indicated a possibility to create a control system that makes it possible for the user to choose between low energy use or short drying time.
The focus of Paper II is to reduce the energy use for a closed cycle tumble dryer. Energy and mass balances were established in order to determine feasible improvements. Energy and mass flows in the dryer indicated that reducing leakage from the internal system of the dryer gave the largest reduction of specific energy use. Insulation of the back cover of the dryer and opening the internal system during the falling drying rate period also gave positive results on the energy use. In total a feasible reduction of the energy use of approximately 17% was calculated.
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Bergman, Ottar. "A Regional Analysis of Changing Climate Conditions and Glacier Mass Balance in Svalbard." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-383930.
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The Arctic archipelago of Svalbard has experienced among the greatest increases in temperature on Earth in the last few decades. The changing climatic conditions have a large impact on the glacier mass balance. This study makes use of a highresolution model dataset with data on climatic and glacier conditions on Svalbard from 1957 to 2018. The model dataset is used to analyse the spatiotemporal variability in glacier mass balance across Svalbard and linking those changes to long-term trends in meteorological conditions. The study is focused on the spatial gradients in trends between two regions in Svalbard, the coldest part of the archipelago, Nordaustlandet and the milder southern part of the main island Spitsbergen. The north eastern (NE) region is found to have a greater increase in annual air temperature over the simulation period with 5.5 °C compared to 3.5 °C for the south western (SW) region. The increase in annual summer temperatures is much smaller with a total increase of 1 °C for the NW and 1.5 °C for the SW. Both regions show a small, but significant, increase of precipitation. Relative humidity and cloud cover in the NE are increasing slightly over the time period, probably due to retreating sea ice cover. Glacier melt and runoff are increasing in both regions, which is contributing to significant negative trends in the mass balance. The increase in melt and run off is stronger in the SW than in the NE. There’s a strong correlation between summer air temperature and glacier mass balance, melt and runoff. Refreezing in the NE is decreasing much faster than in the SW. Refreezing is strongly correlated with annual air temperatures in the NE and not in the SW, probably due to lower temperatures in the NE region.
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Clendon, Penelope Catherine. "Summertime surface mass balance and atmospheric processes on the McMurdo Ice Shelf, Antarctica." Thesis, University of Canterbury. Geography, 2009. http://hdl.handle.net/10092/2630.
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The aim of this research was to demonstrate the relationship between variations in summertime surface mass balance of the McMurdo Ice Shelf and atmospheric processes. The approach encompassed a broad range of techniques. An existing energy balance mass balance model was adapted to deal with debris-covered ice surfaces and modified to produce distributed output. Point based surface energy and mass balance for two key surfaces of the ice shelf were linked to different synoptic types that were identified using a manual synoptic classification. The distributed model was initialised with distributed parameters derived from satellite remote sensing and forced with data from a regional climate model. Patterns of summertime surface mass balance produced by the distributed model were assessed against stake measurements and with respect to atmospheric processes. During the summers of 2003-2004 and 2004-2005 an automatic weather station (AWS) was operated on bare and debris-covered ice surfaces of the McMurdo Ice shelf, Antarctica. Surface mass balance was calculated using the energy balance model driven by the data from the AWS and additional data from permanent climate stations. Net mass balance for the measurement period was reproduced reasonably well when validated against directly measured turbulent fluxes, stake measurements, and continuously measured surface height at the AWS. For the bare ice surface net radiation provided the major energy input for ablation, whereas sensible heat flux was a second heat source. Ablation was by both melt (70%) and sublimation (30%). At the debris-covered ice site investigated, it is inferred that the debris cover is sufficient to insulate the underlying ice from ablation. Synoptic weather situations were analysed based on AVHRR composite images and surface pressure charts. Three distinct synoptic situations were found to occur during the summers, these were defined as Type A, low pressure system residing in the Ross Sea Embayment; Type B, anticyclonic conditions across region; and Type C, a trough of low pressure extending into the Ross Sea Embayment. A dependence of surface energy fluxes and mass balance on synoptic situation was identified for the bare ice surface. The distributed model was found to produce spatial patterns of mass balance which compared well with stake measurements. Mass balance patterns show that the McMurdo Ice Shelf was generally ablating in the west, and accumulating in the east during summer. Areas of enhanced ablation were found which were likely to be caused by the surface conditions and topographic effects on the wind field. The mean summertime surface mass balance across the entire ice shelf for the 2003-2004 and 2004-2005 summers were –2.5 mm w.e. and –6.7 mm w.e. respectively. The differences between the two summers are inferred to be a result of more frequent type A conditions occurring during the summer of 2004-2005.
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Pucci, Justin Matthew. "An analysis of energy balance in a helicon plasma source for space propulsion." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39669.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 107-110).
This thesis covers work done on the mHTX@MIT helicon source as it relates to the analysis of power losses. A helicon plasma is a rather complex system with many potential loss mechanisms. Among the most dominant are optical radiation emission, wall losses due to poor magnetic confinement, and poor antenna-plasma coupling. This work sought to establish a first-order breakdown of the loss mechanisms in the mHTX@MIT helicon source so as to allow for a better understanding of the issues effecting efficiency. This thesis proposes the use of a novel thermocouple array, standard plasma diagnostics, and a simple global energy balance model of the system to determine greater details regarding the losses incurred during regular operation. From this it may be possible, by comparing the heat flux on the tube to the applied magnetic field profile, to gain some insight into the effects of magnetic field geometry on the character of the helicon discharge.
by Justin Matthew Pucci.
S.M.
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Sensoy, Aynur. "Physically Based Point Snowmelt Modeling And Its Distribution In Euphrates Basin." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605945/index.pdf.
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Since snowmelt runoff is important in the mountainous parts of the world, substantial efforts have been made to develop snowmelt models with many different levels of complexity to simulate the processes at the ground, within the snow, and at the interface with the atmosphere. The land-atmosphere interactions and processing influencing heat transfer to and from a snowpack are largely variable and the conceptual representation of this temporal and spatial variability is difficult.
A physically based, two layer point model, is applied to calculate the energy and mass balance of snowmelt in the Upper Karasu Basin, eastern part of Turkey during 2002-2004 snow seasons. The climate data are provided from automated weather stations installed and upgraded to collect quantitative and qualitative data with automated transfer. Each form of energy transfer is evaluated to understand the key processes that have major impact on the snow simulation during accumulation and ablation in two-hourly timesteps. The model performance is evaluated as accurate according to the results, compared with observed snow water equivalents, snow depth and lysimeter runoff yield. In the second part, calculated snowmelt values based on energy and mass balance at the automated stations are related to radiation index model through regression. Then, the spatial patterns of snow water equivalent, solar illumination, albedo and air temperature are used to predict the melt at each grid cell over the whole watershed. The results of distributed model application are evaluated in terms of snow covered area of satellite products, observed snow water equivalent at points through snow pillows and discharge values at the outlet runoff station.
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Eriksson, Rehn Ida. "Mass balance and local characteristics of three glaciers in southern Norway, between 1980 and 2018 : An analysis of the mass balance and the local characteristics of Ålfotbreen, Storbreen and Gråsubreen." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-184671.
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Glaciers are known as climate indicators because of their sensitivity towards climatic perturbations and fluctuations. A majority of the world’s glaciers are currently melting as a response to climatic perturbations. Glaciers in Norway display the same pattern, and the loss of mass have accelerated during the 1990s to this day. The glaciers of interest in this paper is situated in a west to east transect with the maritime Ålfotbreen in the west, to the continental Gråsubreen in the east, with the intermediate Storbreen in between. Differences in the local climate have a significant impact on the future state of glaciers. This paper aims to compare the mass balance, mass turnover and mass balance sensitivity of the three glaciers of interest, between the years 1980 and 2018, to demonstrate the importance of the local climate and characteristics for glacial existence. Mass balance data series of each glaciers’ mass balance was analysed. In addition, development trends of the mean annual summer air temperature for respective glaciers’ region were also conducted. A literature review of relevant reports and publications will be presented and analysed to complement the result of this paper. The results of this paper indicate that the characteristics of respective glacier vary along the increasing continentality of the west to east transect, with the mass balance sensitivity decreasing from west to east. The mass turnover displayed varying patterns, between the years 1980 and 2018. ÅLF had the highest mass turnover for the period and GRÅ the smallest with STO in between. It can be concluded, based on the result of this paper, that the fate of glaciers depends on geographical location and local characteristics. The resemblance between Storbreen and Storglaciären, and the existence of Helagsglaciären who seem to survive against the odds, strengthens the importance of local characteristics.
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McCutcheon, Michael Warren. "Analysis of a 2-3 exchange symmetric neutrino mass matrix." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79048.
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We present an analysis of the requirements of a 2--3 exchange symmetry in the neutrino mass matrix in comparison to the experimentally allowed ranges of neutrino oscillation parameters. The symmetric matrix, being defined at an energy scale appropriate to a right-handed neutrino in a See-saw scheme of mass suppression, is subject to evolution under Supersymmetric Renormalisation Group Equations, in order to interpret the matrix at experimental energies. By way of motivation we discuss the status of neutrino mass in the Standard Model and justify the context of the analysis by examining the mechanisms and evidence for oscillations. We then review the See-saw mechanism and also the process of renormalisation and its implications for bridging disparate energy scales. We present the relevant Renormalization Group Equations and demonstrate the parameterisation of pertinent Renormalization Group effects. Finally, we review previous work analysing this symmetry before updating some of these results and extending the analysis to its global behaviour in the space of both solar and atmospheric neutrino oscillation parameters.
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Wallace, Scott J. "Diesel Engine Energy Balance Study Operating on Diesel and Biodiesel Fuels." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1212586902.
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GUIDOTTI, EMANUELE. "Analysis of the Unsteady Flow in an Aspirated Counter-Rotating Compressor Using the Nonlinear Harmonic Balance Method." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218690946.
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Fairman, Jonathan George. "Investigating paleoclimatic conditions in the tropical Andes using a 2-D model of glacial mass energy balance and ice flow /." Connect to resource, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1211912269.
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Fairman, Jonathan George Jr. "Investigating Paleoclimatic Conditions in the Tropical Andes Using A 2-D Model of Glacial Mass Energy Balance and Ice Flow." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211912269.
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Alizadeh, Ramin. "A new upper limit on the electron anti-neutrino rest-mass." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236237.
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Woocay-Prieto, Arturo. "Groundwater hydrochemical facies, flowpaths and recharge determined by multivariate statistical, isotopic and chloride mass-balance methods." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Ledwith, Alison C. (Alison Catherine). "Thermal mass performance in residential construction : an energy analysis using a cube model." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78146.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 233-241).
Given the pervasiveness of energy efficiency concerns in the built environment, this research aims to answer key questions regarding the performance of thermal mass construction. The work presents the Cube Model, a simplified model of the single-family home. The model combines simplified geometry and equivalent envelope parameters with accurate climate data and internal loading assumptions. The model first addresses the notion as to whether building simplification is a valid means of analysis through a calibration and validation study. Then, the model is used to address three research areas on passive thermal mass: (1) the quantification of thermal mass performance with respect to material thermal properties; (2) the optimization of thermal mass performance for given material parameters; and (3) the sensitivity of thermal mass performance to infiltration and geometry effects. The experiments for wall and slab constructions, to address the first research area, demonstrate that the energy savings from thermal mass are both climate and season dependent. Results provide the magnitude of energy savings in fifty climates across the United States. Optimization experiments on the material thickness and conductivity, to address the second research area, show that constructions do not reach peak thermal mass performance at the same thermal properties in all climates. Sensitivity analyses, to address the third research area, indicate that passive thermal mass and tight construction practices can be mutually optimized without a trade-off of energy performance. Geometry effects demonstrate that modifications in building design can either benefit or hinder the performance of passive thermal mass. The combination of the results suggests that optimum design for thermal mass performance and the resulting energy consumption are climate-dependent and sensitive to many factors aside from material thermal properties.
by Alison C. Ledwith.
S.M.
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Mählkvist, Simon, and Netzell Pontus. "Pulp mill heat and mass balance model : Exploring the benefits and possibilities of process modelling as an applied method in a case study." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-41292.
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This thesis focused on the modelling of a pulping process. The purpose was to see if an accurate model can be crated based on relatively simple premises and if the errors can be identified or analysed. To realise this, the authors conducted a literature study to identify the current state of the art regarding the chemical pulping process. In addition, flow charts and sample data from a case study were examined. Based on the literature review and case study, model assumptions were derived. The model is divided into sixteen components. Where mixing occurs, lumped conditions are assumed. The model has five validation points, four of which are temperatures and a mass flowrate. These are shown as deviations from the measured values. In conclusions, it was the model could produce stable results over a narrow time frame. More so if the transition period at the start of the simulation is overlooked. Several new model assumptions are presented with the purpose to increase accuracy e.g. account for the components ability to store mass.
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Stärner, Nathalie. "Mass balance analysis of phosphorous in Motala Ström River Basin : A focus on lake Roxen and Glan." Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81971.
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Phosphorous (P) has been found to be the limiting nutrient in freshwater systems, directly affecting rates of planktonic growth. The P circulation is very complex, and its pathways through lake systems are difficult to determine. Motala Ström is the biggest watercourse in the south-east of Sweden and an important source of P to the Baltic Sea. The aim of this study is to conduct a P mass balance analysis of the lakes Roxen and Glan over a period of time. The analysis will also include a quality control of the concentrations data. The P concentration data used in this investigation were collected from the Motala Ström River Association, consisting of seasonal or monthly concentration data of Tot-P during the period 1960-2010. Daily water flow data used in this study were modelled by the Swedish Meteorological and Hydrological Institute (SMHI) using the S-HYPE model. P concentration deviations from monthly averages at each sampling station were calculated, followed by a seasonal Mann Kendall trend analysis. At five out of eight sampling stations, negative trends were detected, indicating decreasing concentrations. The exception was the outflow from lake Glan, Stångån and Finspångsån. Linear interpolation of P concentration data was performed to create daily data for the period 1980-2010. Following interpolation, daily transport values were calculated and summed up to annual values. Lake Roxen has acted as a source of P during the whole period 1980-2010, except for one year. Lake Glan has acted as a source during 22 of the 31 years. There is a tendency of Glan to become more of a source over the years, which is in line with the deviation observations, but variation between years makes it necessary to analyse also future data in order to establish any possible trend in P transports. Before construction of wastewater treatment plants, the lakes were certainly sinks of phosphorus. But at least for Roxen, the switch from sink to source was completed before 1980.
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Magnusson, Hans. "From recovery boiler to integration of a textile fiber plant : Combination of mass balance analysis and chemical engineering." Licentiate thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-37266.
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Modern chemical technology is an efficient tool for solving problems, particularly within the complex environment of the pulp and paper industry, and the combination of experimental studies, mill data and mass balance calculations are of fundamental importance to the development of the industry. In this study various examples are presented, whereby chemical technology is of fundamental importance. It is well documented that under normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without problems. However, in the case of alternatives to the kraft recovery boiler, knowledge of more precise data of the molten salts is required for the design calculations. In this study the viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at temperatures relevant for a recovery boiler, i.e. similar to water at room temperature. The presence of non-process elements (NPE) in a typical pulp mill has been investigated. The main input is with regards to the wood, and anticipated problems include; deposits in evaporators, high dead-load in liquor streams, plugging of the upper part of the recovery boiler and decreasing efficiency in the causticization department. Efficient green liquor clarification is of the greatest importance as an efficient kidney for many NPE. Mill data and calculations show that the magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be highly beneficial. The prehydrolysis liquor will contain both sugars and acetic acid. It is however not possible to fully replace the sulphuric acid of the viscose spinning bath with acetic acid of own production. The sulphuric chemicals from the viscose plant can be partly taken care of in the kraft recovery area as well as the viscose plant which can be supplied with alkali and sulphuric acid. Zinc-containing effluents from the viscose plant can be treated with green liquor to precipitate zinc sulphide.Modern chemical technology is an extremely efficient tool for solving problems particularly in a complicated environment such as the pulp and paper industry. Here, examples are studied during which chemical technology is of fundamental importance. At normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without hindrance. However, for certain kraft recovery boiler alternatives, knowledge of more precise data of the molten salts is required. The viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at relevant temperatures. The main input of non-process elements (NPE) is down to the wood, and known problems include deposits in evaporators and decreasing efficiency in the causticization department. Green liquor clarification is an efficient kidney for many NPE. Magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be of significant interest, as the handling of both alkali and sulphuric compounds can be integrated. Problems will however arise as the capacity of the pulping line and the chemical recovery has to be adjusted.
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Marriott, P. "Angular and mass resolved energy distribution measurements with a gallium liquid metal ion source." Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376877.
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Spence, Joshua. "PERVIOUS CONCRETE: A HYDROLOGIC ANALYSIS FOR STORMWATER MANAGEMENT CREDIT." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4176.
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Portland Cement pervious concrete's ability to permit water infiltration has encouraged its use as a stormwater management tool. However, the material has suffered historically poor support due to a number of factors, including failures due to poor mix design and improper construction techniques, concern about lesser structural strength, concern about poor long term performance due to clogging of surface pores and undefined credit for stormwater management. This study focuses on long term performances of pervious concrete parking lots and their stormwater management credit. Before stormwater management credit could be estimated, it was necessary to develop a testing device to gather information from existing pervious concrete parking lots currently in use. Eight parking lots were examined to determine the infiltration rates of the pervious concrete, as well as to verify the soil makeup beneath pavement. A total of 30 cores were extracted from pervious concrete parking lots and evaluated for infiltration rates. Three of the sites had a pervious concrete section that included a gravel reservoir. Infiltration rates were measured using the application of an embedded single-ring infiltrometer. In an attempt to provide an estimate of credit, a mass balance model was created to be used for simulation of the hydrologic and hydraulic function of pervious concrete sections. The purpose of the model is to predict runoff and recharge volumes for different rainfall conditions and hydraulic properties of the concrete and the soil. The field derived hydraulic data were used to simulate infiltration volumes and rainfall excess given a year of rainfall as used in a mass balance operated within a spreadsheet. The results can be used for assessing stormwater management credit.M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
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Daou, Fatma. "Etude expérimentale d'un procédé de dépollution par décharge couronne à barrière diélectrique type pointe(s) - plan : rôle de la simulation numérique et du marquage isotopique." Paris 6, 2002. http://www.theses.fr/2002PA066488.
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Banchik, Leonardo David. "Osmotic mass exchangers for power generation and energy recovery : analysis and analogy to heat exchangers." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81592.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 151-156).
Desalination is an important separation process which can provide water scarce regions with clean water for drinking or for agricultural use. Thermal distillation has historically been the dominant method for obtaining pure water, but today, reverse osmosis (RO) produces a greater percentage of the total desalinated water worldwide by a large margin. Fundamentally, an RO system is a membrane-based osmotic mass exchanger. Another type of membrane-based osmotic process, a subset of forward osmosis (FO) called pressure retarded osmosis (PRO), currently exhibits promise for making desalination more energy efficient and is receiving attention in the literature. PRO exchangers are capable of producing power from two streams of different salinity and recovering energy from the brine stream of any desalination process when paired with water pumps and turbines. RO and PRO exchangers are essentially mass exchangers with a hydraulic or osmotic pressure difference across a membrane acting as the predominant driving potential. Using a simple resistance model for mass transfer applied across an ideal RO and PRO membrane, closed form expressions are developed which relate the performance of a one-dimensional membrane as a function of membrane properties, membrane area, inlet salinities, operating conditions, and flow configuration. These closed form expressions are analogous to the effectiveness versus number of transfer unit (c-NTU) models which have been used for decades in the rating and sizing of heat exchangers. The closed form expressions, along with numerical simulations for validating the models, are used to determine the limits of permeate flux in one-dimensional RO, PRO, and FO membranes; analyze the power performance of a one-dimensional PRO membrane; and determine the viability of using a PRO-based energy recovery device to reduce the net power consumption for RO desalination. The closed-form solutions for determining the performance of the RO and PRO membranes require that osmotic pressure be defined as a linear function of salinity. It is found that for a seawater RO process with a typical recovery ratio of 50% or less, the maximum error associated with linearization is less than 6.1%. For brackish water desalination, where processes typically operate at very high recovery ratios but have brine salinities lower than those encountered in seawater desalination, the error does not exceed 1.8%. For PRO membranes, using varying linearization curves, maximum errors for flux performance of less than 5.5% are incurred by the linear approximation. It is also found that the maximum Second Law efficiency of the power achievable from a one-dimensional PRO membrane is 66.48%. For large membrane areas, the maximum power for a PRO membrane occurs at a hydraulic pressure difference that is not equal to exactly one-half the osmotic pressure difference as reported in literature for zero-dimensional PRO membranes. For PRO membranes used for brine chemical energy recovery from an RO plant treating a feed stream of 35 g/kg, it is found that a wastewater salinity of less than 20 g/kg is required to recover power. Because the membranes within this study have been assumed as ideal, the performance results for flux, power, and power recovery can serve as informative upper bounds.
by Leonardo David Banchik.
S.M.
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Jones, Sarah Melissa Jane. "Mixing, mass transfer and energy analysis across bioreactor types in microalgal cultivation and lipid production." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20064.
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Microalgae are recognised as a source of lipids for bioenergy, nutrients and pharmaceuticals. Photobioreactors, closed vessels for microalgal cultivation, are known to have high energy consumption due to mixing and aeration. Sparging is commonly used for mixing and gas-liquid mass transfer in photobioreactors, but is energy intensive. The aim of this work was to reduce these energy requirements by optimising conventional sparging and considering surface aeration coupled with mechanical agitation as an alternative. An airlift photobioreactor was used as a base for comparison with two novel, surface aerated reactors: oscillatory baffled and wave photobioreactors. The three bioreactors were compared in terms of power input, mixing, CO2 mass transfer, algal growth and lipid production. Prior to comparison, each photobioreactor was optimised based on these parameters. To calculate power input, isothermal gas expansion equations were used for sparged systems and calorimetry was used for mechanically agitation systems. Mixing was investigated using a salt tracer and phenolphthalein indicator and mass transfer was measured using the gassing-in method. Scenedesmus sp., a high lipid-producer, was cultivated in low nitrate media across a range of mixing rates in each photobioreactor.In the airlift photobioreactor a critical minimum CO2 supply rate (of 2.7×10-5 m s-1) was found, below which carbon was limiting and above which energy was spent on sparging without increased productivity (0.20 g L-1 d-1 biomass; 0.03 g L-1 d-1 lipid). In the oscillatory baffled reactor, insufficient mass transfer limited algal productivity (0.11 g L-1 d-1 biomass; 0.02 g L-1 d-1 lipid). The wave reactor had high CO2 mass transfer coefficients (10 – 140 h-1) in comparison to the airlift (2.7 – 40 h-1) and oscillatory baffled reactors (6.3 – 37 h-1). Sufficient biomass productivity (0.18 g L- -1 d-1) and higher lipid productivity (0.045 g L-1 d-1) at lower power input in the wave reactor resulted in higher energy efficiency compared to the airlift reactor. Life cycle analysis of simulated algal biodiesel production showed that bioreactor energy contributed 99% of total energy consumption. Therefore, the global warming potential was reduced by 73% when the airlift reactor was operated at the critical minimum CO2 supply (with gas compression to 2 bar) and a further 19% when the wave reactor was
used. This work offers an energy efficient alternative to sparging, through the generation of a well-mixed wave in a surface aerated bioreactor. It also offers methods for optimisation of energy usage with respect to mixing and aeration. Reducing bioreactor energy consumption is key to feasibility, and was demonstrated here to reduce energy-related environmental burdens.
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Snell, Lloyd Dale. "Force and moment analysis of stacked counter rotating eccentric mass tree shaker energy-wheel system." [Ames, Iowa : Iowa State University], 2008.
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Thuong, Nguyen Thi. "Heavy Metal Contamination in Water and Sediment of To Lich River in Inner City Hanoi." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180494.
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Hung, Aaron. "ENERGY EFFICIENCY AND STATISTICAL ANALYSIS OF BUILDINGS AT CASE WESTERN RESERVE UNIVERSITY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1446477944.
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Elibol, Ercan. "Analysis and Energy Reduction of Humanoid Robot Motions – Stand Up and Sit Down." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5682.
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This research studies the electrical power reduction and control analysis of various motion tasks of a humanoid robot. These motions include standing up and sitting down. Each motion’s tasks have their stable and unstable phases throughout the complete motion cycle. Unstable phases can be caused by gravity forces and improper handling of the upper body of the humanoid robot leaning too forward or backward. Even though most of the dynamic motions seem to be accomplished very simply by humans; standing up and sitting down could create challenges for humanoid robots. Some of the critical challenges researches face are: dynamic nature of motions, humanoid robot joint coordination, whole body balance, stability of the model, limited energy source, energy saving techniques and modeling. Dynamic motions of humanoid robots can be modeled and analyzed to reduce electrical power use. In order to accomplish such energy savings, a researcher needs to study the kinematics, dynamics of a humanoid, and motion tasks with given constraints. The robot in this research is modeled as a planar humanoid robot. All motion tasks of a humanoid robot are characterized in terms of motion variables. These motion variables include joint angular positions, joint angular velocity, joint angular acceleration, humanoid robot center of mass (CoM) position, velocity and acceleration change and center of pressure (CoP) position change. All mathematical models are completed so that electrical power analysis of each task produce comparable results. Humanoid robot joint cost functions related to energy consumption are used to define joint input electrical power used, joint mechanical power used, joint mechanical power dispersion and joint power loss due to torque required.
In this research, a 4-link 3-joint humanoid is modeled for standing up and sitting down tasks. For each task, kinematics and dynamics models are created, motion constraints are found, energy and power usage analysis for whole robot and for individual joint motors are accomplished. By finding the best energy usage per motion variable, humanoid robot used less input electrical power to accomplish the motion task.
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Yeung, Wai Yin. "Environmental concentrations, toxicology, and development of new methods for extraction and mass balance analysis of perfluorinated compounds in environmental samples /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-bch-b2374960xf.pdf.
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Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Biology and Chemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 211-239)
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Fortier, Robin. "Vers un système d'information géographique du couvert nival en Estrie." Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/2651.
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The objective of this research is to develop a system capable of simulating snow depth and snow water equivalent in the Sherbrooke to Mount-Megantic area of Quebec's Eastern Townships using meteorological and digital terrain data as input.The working hypothesis is that meteorological data may drive a point energy and mass balance snow cover model.The model used was developed by the Hydrologic Research Lab (National Weather Service) which was calibrated for local conditions using field data collected during two winters at several sites on Mount-Megantic. Snow water equivalent and depth are used for calibration and validation of the model. Automated snow sensors were also used to obtain temperature calibration data.The snow surveys and correction of the air temperature for elevation improves the estimates of snow depth and water equivalent.The results suggest that data from the Sherbrooke meteorological stations can be used to estimate the snow cover over the area of Eastern Townships. Air temperature extrapolation across the field area is a challenge. However the simulated snow cover conforms generally well with data observed at several stations throughout the region.
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Runeskog, Henrik. "Continuous Balance Evaluation by Image Analysis of Live Video : Fall Prevention Through Pose Estimation." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297541.
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The deep learning technique Human Pose Estimation (or Human Keypoint Detection) is a promising field in tracking a person and identifying its posture. As posture and balance are two closely related concepts, the use of human pose estimation could be applied to fall prevention. By deriving the location of a persons Center of Mass and thereafter its Center of Pressure, one can evaluate the balance of a person without the use of force plates or sensors and solely using cameras. In this study, a human pose estimation model together with a predefined human weight distribution model were used to extract the location of a persons Center of Pressure in real time. The proposed method utilized two different methods of acquiring depth information from the frames - stereoscopy through two RGB-cameras and with the use of one RGB-depth camera. The estimated location of the Center of Pressure were compared to the location of the same parameter extracted while using the force plate Wii Balance Board. As the proposed method were to operate in real-time and without the use of computational processor enhancement, the choice of human pose estimation model were aimed to maximize software input/output speed. Thus, three models were used - one smaller and faster model called Lightweight Pose Network, one larger and accurate model called High-Resolution Network and one model placing itself somewhere in between the two other models, namely Pose Residual Network. The proposed method showed promising results for a real-time method of acquiring balance parameters. Although the largest source of error were the acquisition of depth information from the cameras. The results also showed that using a smaller and faster human pose estimation model proved to be sufficient in relation to the larger more accurate models in real-time usage and without the use of computational processor enhancement.Djupinlärningstekniken Kroppshållningsestimation är ett lovande medel gällande att följa en person och identifiera dess kroppshållning. Eftersom kroppshållning och balans är två närliggande koncept, kan användning av kroppshållningsestimation appliceras till fallprevention. Genom att härleda läget för en persons tyngdpunkt och därefter läget för dess tryckcentrum, kan utvärdering en persons balans genomföras utan att använda kraftplattor eller sensorer och att enbart använda kameror. I denna studie har en kroppshållningsestimationmodell tillsammans med en fördefinierad kroppsviktfördelning använts för att extrahera läget för en persons tryckcentrum i realtid. Den föreslagna metoden använder två olika metoder för att utvinna djupseende av bilderna från kameror - stereoskopi genom användning av två RGB-kameror eller genom användning av en RGB-djupseende kamera. Det estimerade läget av tryckcentrat jämfördes med läget av samma parameter utvunnet genom användning av tryckplattan Wii Balance Board. Eftersom den föreslagna metoden var ämnad att fungera i realtid och utan hjälp av en GPU, blev valet av kroppshållningsestimationsmodellen inriktat på att maximera mjukvaruhastighet. Därför användes tre olika modeller - en mindre och snabbare modell vid namn Lightweight Pose Network, en större och mer träffsäker modell vid namn High-Resolution Network och en model som placerar sig någonstans mitt emellan de två andra modellerna gällande snabbhet och träffsäkerhet vid namn Pose Resolution Network. Den föreslagna metoden visade lovande resultat för utvinning av balansparametrar i realtid, fastän den största felfaktorn visade sig vara djupseendetekniken. Resultaten visade att användning av en mindre och snabbare kroppshållningsestimationsmodellen påvisar att hålla måttet i jämförelse med större och mer träffsäkra modeller vid användning i realtid och utan användning av externa dataprocessorer.
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Boyle, Kristen E. "Ghrelin Reflects Changes in Body Size, Not Energy Availability." Ohio University / OhioLINK, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1121358641.
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Illikainen, M. (Mirja). "Mechanisms of thermomechanical pulp refining." Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514289064.
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Abstract
The objective of this thesis was to obtain new information about mechanisms of thermomechanical pulp refining in the inner area of a refiner disc gap by studying inter-fibre refining and by calculating the distribution of energy consumption in the refiner disc gap.
The energy consumption of thermomechanical pulping process is very high although theoretically a small amount of energy is needed to create new fibre surfaces. Mechanisms of refining have been widely studied in order to understand the high energy consumption of the process, however, phenomena in the inner area of disc gap has had less attention. It is likely that this important position is causing high energy consumption due to the high residence time of pulp located there.
The power distribution as a function of the refiner disc gap was calculated in this work. The calculation was based on mass and energy balances, as well as temperature and consistency profiles determined by mill trials. The power distribution was found to be dependent on segment geometry and the refining stage. However, in the first stage refiner with standard refiner segments, a notable amount of power was consumed in the inner area of the disc gap.
Fibre-to-fibre refining is likely to be the most important mechanism in the inner area of disc gap from the point of view of energy consumption. In this work the inter-fibre refining was studied using equipment for shear and compression. Fibre-to-fibre refining was found to be an effective way to refine fibres from coarse pulp to separated, fibrillated and peeled fibres if frictional forces inside the compressed pulp were high enough. It was proposed that high energy of today’s thermomechanical pulping process could derive from too low frictional forces that heated pulp and evaporated water without any changes in fibre structure.
The method to calculate power distribution and results of fibre-to-fibre refining experiments may give ideas for developing today’s thermomechanical pulp refiners’ or for developing totally new energy saving mechanical pulping processes.
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Réveillet, Marion. "Sensibilité du bilan de masse des glaciers alpins aux variables atmosphériques et topographiques : Observations et simulations." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU038/document.
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Les glaciers intègrent naturellement des informations hydrologiques et énergétiques dans des régions climatiques variées du globe et sont sensibles à des changements minimes de bilan d’énergie de surface. Parmi les paramètres mesurés in-situ traduisant les variations climatiques, le bilan de masse de surface est la variable directement reliée aux conditions atmosphériques qui contrôlent les processus d’accumulation et d’ablation. Un grand nombre de modèles, de complexités diverses, existent pour simuler l’évolution du bilan de masse. Cependant, des questions perdurent quant à l’utilisation de l’approche la plus appropriée, notamment sur de longues périodes de temps. Basés sur de longues séries de mesures réalisées sur quatre glaciers des Alpes françaises (issues du service d’observation GLACIOCLIM), ces travaux de thèse ont pour but d’étudier la sensibilité du bilan de masse aux variables atmosphériques et topographiques, afin d’identifier celles essentielles pour contraindre les modèles.En s’appuyant tout d’abord sur une approche empirique, nos résultats indiquent que pour chaque glacier, la variabilité temporelle de l’ablation s’explique principalement par la variabilité de la température tandis que la variabilité spatiale de la fonte de la neige et de la glace est largement gouvernée par l’insolation. Néanmoins, à l’échelle du glacier, considérer l’insolation en plus de la température ne conduit pas à une amélioration de la performance des modèles empiriques et un modèle type degré-jour apparaît suffisant pour simuler son bilan de masse. L’utilisation du modèle à base physique SURFEX/ISBA-Crocus a permis d’étudier la sensibilité du bilan de masse estival à chacune des variables du bilan d’énergie de surface. Le modèle s’avère très performant pour la simulation des bilans spatialisés, mais nécessite un forçage météorologique précis et distribué spatialement. En particulier, le vent, souvent complexe à représenter dans les modèles atmosphériques,apparaît comme un facteur prépondérant pour modéliser correctement les processus de fonte. Avec des forçages météorologiques bien contraints, ces deux approches (empirique et physique) se révèlent très performantes quant à la modélisation du bilan de masse estival. Toutefois, nos résultats montrent que les bilans annuels restent très conditionnés par les bilans hivernaux du fait de la rétroaction de l’albédo de surface. Une attention particulière a donc été portée sur la simulation de l’accumulation.A partir des données de l’observatoire GLACIOCLIM, notre étude n’a pas permis d’établir de relation significative entre la variabilité spatio-temporelle des bilans hivernaux et les variables morpho-topographiques.Pour cette raison, une campagne spécifique basée sur des mesures LiDAR a été mise en œuvre au Col du Midi (Massif du Mont-Blanc) afin d’affiner le réseau de mesures et d’améliorer la compréhension de la variabilité spatio-temporelle de la couverture neigeuse. Nos résultats montrent la complexité d’obtenir des mesures d’accumulation par différence de MNT, du fait des vitesses d’émergence/submergenceGlaciers naturally record hydrological and energetic information into varied climatic regions of the world, and are sensitive to small changes in their surface energy balance. The glacier surface mass balance is directly linked to the atmospheric variables which control accumulation and ablation processes. Many models, with different complexities, enable simulations of mass balance evolution, but some questions arise about the best approach to use, especially over long time periods. Based on long measurement series on four glaciers in the French Alps (GLACIOCLIM observatory), this thesis aims at studying the mass balance sensitivity to climatic variations, to identify relevant meteorological variables for modelling. Based on an empirical approach performed on each glacier, temperature was found to be the main driver of temporal ice/snow ablation variability while solar radiations strongly influence the spatial distribution of summer mass balance. However, at glacier scale, to include solar radiation in melt models does not improvethe performances and a classical degree-day model is sufficient to simulate glacier-wide mass balance.The snowpack model SURFEX-ISBA-Crocus was then used to study summer mass balance sensitivity to all surface energy balance fluxes. Results indicate good performances of the model to simulate mass balance at each stake, but it requires accurate meteorological forcing. In particular wind, generally difficult to assessby atmospheric models, appears as a key factor for an accurate ablation modelling. Our work emphasizes that both physical and empirical approaches are very efficient for ablation modeling when forced with accurate meteorological data. Yet, annual mass balances remain very sensitive to wintermass balance due to the surface albedo feedback. For this reason, simulating accumulation processes remainsas important as ablation modelling. Using GLACIOCLIM data measurements, our study failed to find relevant relationship between winter mass balance and topographical variables such as slope, aspect, elevation, due to insufficient spatio-temporal resolution. To fill this gap of measurements, we set up a dedicated field campaign to improve our understanding of the spatio-temporal variability of the snow depth distribution on Alpineglaciers. This year-round campaign was performed using LiDAR acquisitions at Col du Midi (Mont Blancmassif). Results underline the complexity of accurate accumulation measurements from DEM differences due to submergence/emergence velocities
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EL-HAJJE, REFAAT Safety Science Faculty of Science UNSW. "A SIMULTANEOUS MEASUREMENT OF THE ANGULAR DISTRIBUTION, MASS AND KINETIC ENERGY OF 235U AND 232Th FISSION FRAGMENTS." Awarded by:University of New South Wales. School of Safety Science, 2000. http://handle.unsw.edu.au/1959.4/17612.
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Simultaneous measurements of the angular distribution, mass distribution and average total kinetic energy of fission fragments produced by the neutron-induced fission of 235U and 232Th have been made using a gridded ionisation chamber. The neutron energy range used was thermal to 1.9 MeV for 235U and 1.4 to 1.7 MeV for 232Th. The following topics were investigated: the interdependence of the fission fragment angular and mass distribution; the anomalous behaviour of fragment anisotropy for 235U(n,f) at neutron energies En below 150 keV; the possible existence of a third symmetric mass peak for 232Th(n,f); the mass fine structure in 235U(n,f) and 232Th(n,f); and the dependence of the fission fragment average total kinetic energy on the excitation energy of the fissioning nucleus. For this study, mono-energetic neutrons were produced by the and reactions. Four signals produced by the fission chamber were fed into a data acquisition system and processed by a specially modified comprehensive computer program. The results indicate that there is no interdependence between the angular and mass distributions of fragments for 235U(n,f) and for 232Th(n,f). The angular distribution of 235U fission fragments showed an anisotropy of less than one for En below 150 keV. For 232Th, the expected minimum in the anisotropy near En = 1.6 MeV was confirmed. No evidence for a third peak in the mass symmetry region of 232Th(n,f) was observed, within the yield sensitivity limitation of the chamber. Fine structure was observed in the mass yield distributions for 235U(n,f) and 232Th(n,f) at mass locations predicted by theory. The fission fragment average total kinetic energy for 235U(n,f) and 232Th(n,f) showed no significant dependence on the excitation energy of the fissioning nucleus. Possible reasons for some of these results are advanced.
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Meesala, Vamsi Chandra. "Modeling and Analysis of a Cantilever Beam Tip Mass System." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83378.
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We model the nonlinear dynamics of a cantilever beam with tip mass system subjected to different excitation and exploit the nonlinear behavior to perform sensitivity analysis and propose a parameter identification scheme for nonlinear piezoelectric coefficients.
First, the distributed parameter governing equations taking into consideration the nonlinear boundary conditions of a cantilever beam with a tip mass subjected to principal parametric excitation are developed using generalized Hamilton's principle. Using a Galerkin's discretization scheme, the discretized equation for the first mode is developed for simpler representation assuming linear and nonlinear boundary conditions. We solve the distributed parameter and discretized equations separately using the method of multiple scales. We determine that the cantilever beam tip mass system subjected to parametric excitation is highly sensitive to the detuning. Finally, we show that assuming linearized boundary conditions yields the wrong type of bifurcation.
Noting the highly sensitive nature of a cantilever beam with tip mass system subjected to parametric excitation to detuning, we perform sensitivity of the response to small variations in elasticity (stiffness), and the tip mass. The governing equation of the first mode is derived, and the method of multiple scales is used to determine the approximate solution based on the order of the expected variations. We demonstrate that the system can be designed so that small variations in either stiffness or tip mass can alter the type of bifurcation. Notably, we show that the response of a system designed for a supercritical bifurcation can change to yield a subcritical bifurcation with small variations in the parameters. Although such a trend is usually undesired, we argue that it can be used to detect small variations induced by fatigue or small mass depositions in sensing applications.
Finally, we consider a cantilever beam with tip mass and piezoelectric layer and propose a parameter identification scheme that exploits the vibration response to estimate the nonlinear piezoelectric coefficients. We develop the governing equations of a cantilever beam with tip mass and piezoelectric layer by considering an enthalpy that accounts for quadratic and cubic material nonlinearities. We then use the method of multiple scales to determine the approximate solution of the response to direct excitation. We show that approximate solution and amplitude and phase modulation equations obtained from the method of multiple scales analysis can be matched with numerical simulation of the response to estimate the nonlinear piezoelectric coefficients.Master of Science