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1
Rutter, Andrew U. "Survival and Capture Efficiency of River Otters in Southern Illinois." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2260.
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River otter (Lontra canadensis) populations in Illinois have rebounded considerably after >80 years of harvest protection and a successful reintroduction program. However, few studies of river otter ecology exist in the Midwestern U.S. where river otter numbers have increased in recent decades. Capturing study animals safely and efficiently is a critical part of wildlife research, and difficulties associated with live capture of river otters have contributed to the dearth of research on the species. Furthermore, estimating survival rates and identifying causes of mortality are important in effectively managing river otters. To address these knowledge gaps, my objectives were determine survival rates and mortality causes for river otters in southern Illinois, and to measure injury rates of river otters captured using Comstock traps. During 2014-16, I captured 42 river otters 49 times at Crab Orchard National Wildlife Refuge (CONWR) in southern Illinois. Eight river otters (3 M, 5 F) were captured in foot-hold traps during 788 trap nights (1 capture/88 trap nights), and the remaining 34 (19 M, 15 F) were captured in Comstock traps during 2,540 trap nights (1 capture/64 trap nights). I detected no significant differences in efficiency or escape rate between the 2 trap types, but Comstock traps did have higher rates for both unavailability and non-target captures. Eleven of the 20 river otters inspected for injuries received some type of injury as a result of capture in a Comstock trap (55%). The most common injury was claw loss (45%), followed by tooth fracture (25%), and lacerations (10%). The ease of setting the Comstock traps and of releasing non-target captures made them a more appealing option than foot-hold traps; however, river otters have a propensity for doing permanent damage to their teeth when live captured in Comstock traps. My study provides information on the functionality and safety of a novel live capture method for river otters. Thirty-four (16 F, 18 M) river otters were successfully radio-marked and monitored for survival for a total of 8,235 radio-days (¯x days/river otter = 242.2 ± 20.6 [SE throughout]). Two river otters (2 M) died during the period of radio-telemetry monitoring: 1 was trapped during nuisance wildlife control activities at an adjacent fish hatchery, and the other died of unknown causes. Annual survival rates were 1.0 ± 0.00 (lower confidence bound = 0.83) and 0.85 ± 0.09 for females and males, respectively, and similar between sexes (χ_1^2 = 1.7, P = 0.19). Pooled-sex breeding season survival was 0.96 ± 0.04. Trapping was the primary source of mortality over the course of my study. After radio-telemetry ended, 2 river otters were harvested by recreational trappers, at 114 (1 M) and 120 (1 F) weeks post-capture, and 1 male was killed by a vehicle collision at 52 weeks post-capture. Primary mortality sources for river otters in southern Illinois are similar to those reported elsewhere (i.e., trapping and vehicle collisions). Although I found no significant difference in survival rates between sexes, the majority of otters that died during my study were male (4 M, 1 F). As river otters occupying CONWR are protected from harvest, males may be more likely to leave the confines of CONWR, thereby putting themselves at greater risk to recreational trapping mortality. My study provides useful demographic information for Illinois’ recently-recovered river otter population.
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Ratnesar-Shumate, Shanna. "Physical capture efficiency and disinfection capability of iodinated fiber media." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010485.
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Willis, William Brandon. "Estimating the capture efficiency of a vegetative environmental buffer using Lidar." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/3219.
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Particulate matter expelled from tunnel-ventilated animal feeding operations (AFOs) is known to transport malodorous compounds. As a mitigation strategy, vegetative environmental buffers (VEBs) are often installed surrounding AFOs in order to capture particulates and induce lofting and dispersion. Many farmers are or are interested in implementing VEBs, yet research supporting their efficacy remains sparse.
Currently, point measurements, often combined with models, are the primary means by which emission rates from AFOs and VEB performance has been investigated. The existing techniques lack spatial resolution and fail to assign the observed particulate reduction to capture, lofting, or dispersion.
In recent years, lidar has emerged as a suitable partner to point measurements in agricultural research. Lidar is regarded for its ability to capture entire plume extents in near real time. Here, a technique is presented for estimating the capture efficiency of a VEB using lidar. An experiment was conducted in which dust was released upwind of a VEB at a known rate, and the emission rate downwind of the VEB was estimated using an elastic scanning lidar. Instantaneous lidar scans showed periodic lofting well above the VEB, but when scans were averaged over several hours, the plumes appeared Gaussian. The experiment revealed a capture efficiency ranging from 21-74β, depending on the time of day. The methodology presented herein addresses deficiencies in the existing techniques discussed above, and the results presented add to the lacking body of research documenting VEB capture efficiency.
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Isse, Abdullahi. "Capacity of cover crops to capture excess fertilizer and maintain soil efficiency." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0021/MQ37132.pdf.
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McCabe, Christie Renee. "A novel antibody based capture matrix utilizing human serum albumin and streptococcal Protein G to increase capture efficiency of bacteria." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002811.
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Soundararajan, Rengarajan. "Efficiency loss analysis for oxy-combustion CO2 capture process : Energy and Exergy analysis." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14177.
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Natural gas combined cycles with oxy-fuel combustion is expected tobe an important component of the future carbon constrained energyscenario. An oxy-combustion power cycle enables the fuel to burn in anitrogen free environment and thereby helps separate the CO2 streamfor storage. Depending on the oxygen source and purity, the CO2stream may need further purification via a purification unit (CPU)before compressing it to a high pressure for storage. The major energy penalty in this type of power cycle is the production of oxygenand the downstream purification to remove volatiles. It is this energypenalty which results in the cost of avoiding the CO2 emissions to theatmosphere.Cryogenic Air Separation Units (ASU) for oxygen production con-tribute to approximately 20% of the total energy penalty of such powerplants. Oxygen Transport Membranes (OTM) for oxygen production offers a potential solution to reduce the energy penalty of oxy-combustion natural gas cycles. The energy penalties associated withOTMs are that membranes operate at high temperatures and requirea sweep gas to establish an oxygen partial pressure difference betweenthe feed and permeate streams. Further, while the Cryogenic ASUhas minimum integration with the power process, oxy-combustion cycles with OTMs are tightly integrated with the power plant. Thusthe contributions to efficiency penalty in an OTM-based cycles aredistributed and not easily identified.The objective of the thesis is to answer the question: "Where doesthe plant efficiency loss originate in oxy-combustion CO2 capture process using Oxygen Transport Membrane as compared to one withcryogenic ASU?" The contribution of the work will be to highlight thelosses at the sub-process and at the equipment level.This work studies three different cases of oxy-combustion naturalgas combined cycles (NGCC) with CO2 capture. The baseline scenario, modified/improved scenario and the advanced scenario. Thebaseline scenario is a simple oxy-combustion NGCC power plant withASU as the oxygen source. Various losses associated with this systemare studied in detail. The modified/improved scenario involves analysis of possible modifications to the baseline case and applying theresults in-order to improve the baseline case. The modified scenario isexpected to have a better overall plant performance. The advancedscenario involves usage of OTM for oxygen production.The power plants are simulated in Aspen HYSYS and plant massand heat balances are calculated. Using the stream enthalpy, entropyand composition, we can calculate the stream exergy values. Controlvolumes help us analyze the component and sub-system exergy lossesand arrive at the overall power plant exergetic efficiency. The base-line power plant scheme is found to have an exergetic efficiency of 47percentage points with a thermal efficiency of 49.6 percentage, withcapture.The modified power plant scheme is obtained by increasing the gasturbine pressure ratio and this has a significant impact on the over-all system design and hence the performance. The modified systemhas exergetic and thermal efficiency of 49 and 51 percentage pointsrespectively. The advanced power plant with OTM, also called as theAdvanced Zero Emissions Powerplant (AZEP) has an exergetic efficiency of 51 and a thermal efficiency of 53.4 percentage. In all the cases, the combustor where most of the fuel is burnt is responsible formajority of the exergy destruction.There is potential for improving the ASU and thereby achieving alesser specific oxygen production power and also due to system integration and other improvements, the overall oxy-combustion NGCCpower plant is expected to play an important role in 5 - 10 years. Alsoas the working fluid is different from that of a normal air based powerplant, significant work needs to be done in the gas turbine and compressor part. Also detailed cost estimations, reliability and flexibilitystudies, operability and safety related studies need to be carried outin-order to boost the confidence in oxy-fuel NGCC power plants andtake it to the next phase.
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Das, Debarun. "Enhanced capture of magnetic microbeads using sequentially switched electroosmotic flow." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1427962332.
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Festger, Adam Douglas. "Analysis of hydraulic capture zones and efficiency under time-varying flow and pumping conditions." Thesis, The University of Arizona, 2000. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2000_30_sip1_w.pdf&type=application/pdf.
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Dixon, Daniel. "Effects of environmental and clinical interferents on the host capture efficiency of immobilized bacteriophages." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123296.
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The concept of using bacteriophages to control populations of pathogenic bacteria is gaining momentum, driven mainly by the growing global crisis over antibiotic resistance in both the natural environment and healthcare settings. Bacteriophages (phages) are natural predators of bacteria and are innocuous to humans, animals or plants. Functionalizing surfaces with phage offers the promise of designing devices that can actively capture and deactivate bacteria such as water filters, wound dressings or antibacterial coatings. Our laboratory has previously proven the feasibility of this idea in a clean water matrix, demonstrating that phage-functionalized surfaces are promising candidates for selective capture and inactivation of bacterial pathogens. However, the complex composition of many natural samples (e.g., surface waters, waste water, blood, etc.) can potentially interfere with the interaction of phage and its bacterial host, leading to a decline in the efficiency of the phage-functionalized surface. In this study, the bacterial capture efficiency of phage-functionalized surfaces was assessed in the presence of potential environmental and biomedical interferents. Two phage-bacteria systems were used in this study, namely PRD1 with Salmonella Typhimurium and T4 with Escherichia coli. The potential environmental interferents tested were humic and fulvic acids, colloidal latex microspheres (as a model for environmental colloids), extracellular polymeric substances (EPS), as well as a natural unfiltered groundwater. Albumin, fibrinogen, and blood serum were also tested as representative interferents of interest for biomedical applications such as wound dressings. The inactivation of the selected phages by the potential interferents was first evaluated for each phage suspended in aqueous media containing each interferent. Next, the bacterial (host) capture efficiency of a phage-functionalized substrate was evaluated in the presence of each interferent. Interestingly, humic and fulvic acids reduced the capture efficiency of T4-functionalized surfaces by over 60%, even though they did not lead to inactivation of the suspended virions. Neither humics nor fulvics affected the capture efficiency of PRD1. EPS and human serum decreased the host capture efficiency for immobilized PRD1 and T4 by over 70%, and also impaired the infectivity of the non-immobilized (planktonic) phage, although to a much lower extent (less than 50%). The fundamental mechanisms leading to the observed decrease in performance of the phage-functionalized surfaces in the presence of selected interferents is discussed in detail in the thesis. These findings demonstrate the inadequacy of traditional phage selection methods (i.e., infectivity of suspended phage towards its host in clean buffer) for designing antimicrobial surfaces and further highlight the importance of taking into account the environmental conditions in which the immobilized phage is expected to function.La résistance, de plus en plus avérée, aux antibiotiques a motivé l'intérêt d'utiliser des bactériophages pour le traitement, le contrôle et la détection de populations bactériennes pathogènes. Des bactériophages aux surfaces fonctionnalisées ont été mis au point pour une application à des surfaces antimicrobiennes, en tant que biocapteurs, dans des dispositifs médicaux permanents ou des pansements ainsi que dans des dispositifs pour la capture des bactéries. Dans cette étude, l'efficacité de capture des bactéries, de deux modèles de phage à surface fonctionnalisée, a été évaluée en présence de différents interférents potentiels environnementaux et biomédicaux. Les deux systèmes phages-bactéries utilisées dans cette étude sont le PRD1 de Salmonella Typhimurium et le T4 d'Escherichia coli. Les interférents potentiels testés comprenaient : les acides humiques et fulviques, les eaux souterraines naturelles, les microsphères de latex colloïdales, des substances polymères extracellulaires (SPE), l'albumine, le fibrinogène et le sérum. Tout d'abord, l'inactivation des phages sélectionnés par les interférents potentiels a été évaluée pour les phages en suspension dans des milieux aqueux. Ensuite, l'efficacité de capture des bactéries d'une surface de verre phage-fonctionnalisée a été évaluée en présence de différents interférents. Une SPE a été identifiée pour réduire l'efficacité de captage des PRD1 et des T4, et a également été trouvée pour réduire l'activité des PRD1 en suspension. Le sérum a diminué l'activité des deux phages en suspension, et a également abouti à une réduction de l'efficacité de capture bactérienne. L'addition d'acides humiques ou fulviques réduit l'efficacité de capture des surfaces T4-fonctionnalisées, mais n'a pas conduit à l'inactivation des virions en suspension. Ces résultats soulignent la nécessité pour une surface potentielle de phage fonctionnalisée, d'être testée pour ses performances dans les conditions d'application finale.
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Thorbjörnsson, Anders. "Carbon Capture and Storage : Energy penalties and their impact on global coal consumption." Thesis, Uppsala universitet, Naturresurser och hållbar utveckling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235442.
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Coal has been used as a fuel for electricity generation for centuries. Inexpensive electricity from coal has been a key component in building large industrial economies such as USA and China. But in recent decades the negative aspects of coal, mainly carbon dioxide emissions, has changed the view on the fuel. Carbon capture and storage (CCS) is a solution to be able to continue using coal as an energy source, while limiting carbon emissions. One of the drawbacks of CCS is the energy need associated with the capture process, the energy penalty. This study aims to gather and analyze the energy penalties for the most developed types of carbon capture technologies. It also aims to model how the implementation of CCS would affect the future coal consumption. The results show that the range of energy penalties for a given type of technology is wide. Despite obtaining the energy penalty with the same simulation software, the energy penalty for post- combustion with MEA can range between 10.7% and 39.1%. Comparing mean energy penalties show that pre-combustion capture is the most efficient capture method (18.4% ± 4.4%) followed by oxy- fuel (21.6% ± 5.5%) and post-combustion (24.7% ± 7.9%). Further on, CCS implementation scenarios were compared and used as a starting point for coal consumption calculations. Three pathways were constructed in order to investigate how different distributions of technologies would affect the amount of needed coal. The pathways describe a implementation with only the most efficient technology, the least efficient and a middle option. The results suggest that a large scale implementation of CCS on coal power plant will have a significant impact on the global coal consumption. Under certain assumptions it takes up to 35 % more coal to deliver the same amount electricity with CCS in comparison without CCS. It is also found that certain implementation scenarios will struggle to produce the amount of coal that is needed to power the plants. A sensitivity analysis was performed to examine the impact of assumptions made on for instance plant efficiencies. The analysis shows that optimistic assumptions on development in plant efficiency and deploying only the best technology, uses less coal than a development without CCS and with current plant efficiencies.
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Hanak, Dawid Piotr. "Evaluation of efficiency improvements and performance of coal-fired power plants with post-combustion CO2 capture." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/10239.
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The power sector needs to be decarbonised by 2050 to meet the global target for greenhouse gas emission reduction and prevent climate change. With fossil fuels expected to play a vital role in the future energy portfolio and high efficiency penalties related to mature CO2 capture technologies, this research aimed at evaluating the efficiency improvements and alternate operating modes of the coal-fired power plants (CFPP) retrofitted with post-combustion CO2 capture. To meet this aim, process models of the CFPPs, chilled ammonia process (CAP) and calcium looping (CaL) were developed in Aspen Plus® and benchmarked against data available in the literature. Also, the process model of chemical solvent scrubbing using monoethanolamine (MEA) was adapted from previous studies. Base-load analysis of the 580 MWel CFPP retrofits revealed that if novel CAP retrofit configurations were employed, in which a new auxiliary steam turbine was coupled with the boiler feedwater pump for extracted steam pressure control, the net efficiency penalty was 8.7–8.8% points. This was close to the 9.5% points in the MEA retrofit scenario. Conversely, CaL retrofit resulted in a net efficiency penalty of 6.7–7.9% points, depending on the fuel used in the calciner. Importantly, when the optimised supercritical CO2 cycle was used instead of the steam cycle for heat recovery, this figure was reduced to 5.8% points. Considering part-load operation of the 660 MWel CFPP and uncertainty in the process model inputs, the most probable net efficiency penalties of the CaL and MEA retrofits were 9.5% and 11.5% points, respectively. Importantly, in the CaL retrofit scenarios, the net power output was found to be around 40% higher than that of the CFPP without CO2 capture and double than that for the MEA retrofit scenario. Such performance of the CaL retrofit scenario led to higher profit than that of the 660 MWel CFPP without CO2 capture, especially if its inherent energy storage capability was utilised. Hence, this study revealed that CaL has the potential to significantly reduce the efficiency and economic penalties associated with mature CO2 capture technologies.
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Jönsson, Tim. "Efficiency determination of automated techniques for GUI testing." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Informationsteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-24146.
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Efficiency as a term in software testing is, in the research community, a term that is not so well defined. In the industry, and specifically the test tool industry, it has become a sales pitch without meaning. GUI testing in its manual form is a time consuming task, which can be thought of as repetitive and tedious by testers. Using human testers to perform a task, where focus is hard to keep, often ends in defects going unnoticed. The purpose of this thesis is to collect knowledge on the area efficiency in software testing, but focusing more on efficiency in GUI testing in order to keep the scope focused. Part of the purpose is also to test the hypothesis that automated GUI testing is more efficient than traditional, manual GUI testing. In order to reach the purpose, the choice fell to use case study research as the main research method. Through the case study, a theoretical study was performed to gain knowledge on the subject. To gain data used for an analysis in the case study, the choice fell on using a semi-experimental research approach where one automated GUI testing technique called Capture & Replay was tested against a more traditional approach towards GUI testing. The results obtained throughout the case study gives a definition on efficiency in software testing, as well as three measurements on efficiency, those being defect detection, repeatability of test cases, and time spent with human interaction. The result also includes the findings from the semi-experimental research approach where the testing tools Squish, and TestComplete, where used beside a manual testing approach. The main conclusion deducted in this work is that an automated approach towards GUI testing can become more efficient than a manual approach, in the long run. This is when efficiency is determined on the points of defect detection, repeatability, and time.
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Miller, Samuel A. "Electroosmotic Flow Driven Microfluidic Device for Bacteria Isolation Using Magnetic Microbeads." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1544101007184486.
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Wang, Zhonglu. "Design of a Boron Neutron Capture Enhanced Fast Neutron Therapy Assembly." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14100.
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A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient¡¯s head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm B-10 for a 5.0-cm tungsten filter and 29.8% for an 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively.
To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The measured dose enhancement at 5.0-cm depth in the head phantom for the 5.0-cm thick tungsten filter is (16.6 ¡À 1.8)%, which agrees well with the MCNP simulation of the simplified BNCEFNT assembly, (16.4¡À 0.5)%. The error in the calculated dose enhancement only considers the statistical uncertainties. The total dose rate measured at 5.0-cm depth using the non-borated ion chamber is (0.765 ¡À 0.076) Gy/MU, about 61% of the fast neutron standard dose rate (1.255Gy/MU) at 5.0-cm depth for the standard 10x10 cm2 treatment beam.
The increased doses to other organs due to the use of the BNCEFNT assembly were calculated using MCNP5 and a MIRD phantom.
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Chan, Wai Nam 1964. "Avaliação da mitigação das emissões de CO2 para uma refinaria de petróleo no Brasil." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265828.
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Orientador: Arnaldo Cesar da Silva WalterTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Atualmente o setor de refino de petróleo é responsável por cerca de 5% do total das emissões de CO2 relacionadas ao uso de energia no Brasil. O objetivo principal desta tese é avaliar as opções de mitigação de CO2 e seus respectivos custos para a REPLAN, que é a maior refinaria nacional. A revisão bibliográfica, a obtenção de informações adicionais na refinaria e a análise crítica das informações obtidas possibilitaram realizar uma prospecção de tecnologias de mitigação de emissões de CO2 para a indústria de refino. Através da utilização do conceito de Custo Marginal de Abatimento foi possível realizar a análise econômica das opções de mitigação de CO2 existentes na REPLAN. Os resultados mostram que melhorias de eficiência energética e substituição de combustível representam as estratégias mais promissoras para a redução das emissões de CO2 no curto prazo. Os custos de abatimento estimados são negativos (média de -130 US$/t CO2), o que significa que as medidas já são atrativas e poderiam ser implementadas imediatamente. Entretanto, o potencial global de redução é relativamente baixo (0,23 milhão de t CO2/ano, ou 6% do total das emissões). É mostrado ainda que a técnica de captura e armazenamento de carbono (CCS) oferece potencial para reduções mais significativas de emissões no longo prazo (até 1,62 milhão de t CO2/ano, ou 43% do total das emissões), mas os custos são bem maiores e, no cenário considerado, se situam na faixa de 64-162 US$/t de CO2, dependendo da fonte de emissão de CO2 (regeneradores de unidades de craqueamento catalítico ou unidades de geração de hidrogênio) e da tecnologia considerada para a captura de CO2 (oxi-combustão ou pós-combustão). Nesta tese é mostrado que as oportunidades remanescentes de melhoria de eficiência energética são limitadas na REPLAN. Dessa forma, CCS seria tecnicamente viável para reduzir as emissões de CO2, mas há uma série de questões políticas, legais, financeiras e técnicas que precisam ser superadas. Em caso de um cenário de restrição de emissões de gases de efeito estufa no Brasil, uma opção é considerar uma estratégia de mitigação de CO2 em duas etapas. A implementação de CCS poderia ser adiada para um período após 2020 até que a tecnologia se torne economicamente viável. Finalmente, o estudo de caso da REPLAN pode ser considerado como um plano de ação replicável para outras refinarias brasileiras
Abstract: Currently the oil refining sector is responsible for approximately 5% of Brazilian energy related CO2 emissions. The main objective of this thesis is to evaluate the CO2 mitigation options and their costs to REPLAN, which is the largest national refinery. The literature review, the achievement of additional information at the refinery and the critical analysis of information enabled to conduct a survey of CO2 emissions mitigation technologies for the refining industry. By using the concept of Marginal Abatement Cost it was possible to conduct an economic analysis of existing CO2 mitigation options at REPLAN. The results show that energy efficiency improvements and fuel substitution represent the most promising strategies for reducing CO2 emissions in the short term. The estimated abatement costs are negative (on average, about -130 US$/t CO2), meaning that the measures are already cost-effective and could be implemented immediately. However, the overall abatement potential is relatively low (0.23 million t CO2/year, or 6% of the total emissions). It is further shown that the technique of carbon capture and storage (CCS) offers the potential for more significant emission reductions in the long term (up to 1.62 million t CO2/year, or 43% of the total emissions), but costs are much higher and, in the considered scenario, are in the range of US$ 65-164/t CO2, depending on the CO2 emission source (regenerators of catalytic cracking units or hydrogen production units) and the CO2 capture technology considered (oxyfuel combustion or post-combustion). In this thesis it is shown that remaining opportunities of energy efficiency improvement are limited at REPLAN. Thus, CCS would be technically feasible to reduce CO2 emissions, but there are a number of political, legal, financial and technical issues that must be overcome. In case of a scenario with restriction of greenhouse gas emissions in Brazil, one option is to consider a two-step CO2 mitigation strategy. CCS implementation could be postponed for a period after 2020 until the technology becomes economically viable. Finally, the case study of REPLAN can be considered as a replicable action plan to other Brazilian refineries
Doutorado
Planejamento de Sistemas Energeticos
Doutor em Planejamento de Sistemas Energéticos
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Santos, Caio Felipe de Paula [UNESP]. "Análise termoeconômica e eficiência ecológica de uma termoelétrica com absorção química de CO2." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/138083.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A geração de energia elétrica em usinas termoelétricas de ciclo combinado tem se mostrado muito importante para o Brasil apesar de operar com custo maior do que a geração através de hidroelétricas. Neste trabalho, foram realizadas análises termoeconômica e ecológica, baseadas nos princípios da Termodinâmica (energia e exergia), aplicados em usina termoelétrica de ciclo combinado de 500 MW. Para este trabalho foram consideradas duas configurações para a planta: a primeira configuração é a padrão (sem considerar equipamento de redução de emissão de CO2), e a segunda que considera a implementação do processo de captura, armazenamento e compressão de CO2 (CAC). O principal objetivo do trabalho é estudar e comparara as diferenças nas eficiências termodinâmicas e ecológicas da planta (operando nas duas condições) e as alterações nos custos de produção de energia elétrica gerada, em vista da instalação do processo de CAC.
The Electric Power Generation in combined cycle power plants has been very important for Brazil despite having a higher cost than the generation through hydropower plants. In this work, there were performed thermeconomical and ecological analyzes, based on thermodynamic principles (energy and exergy) in a 500 MW combined cycle power plant. For this work there were considered two settings for this plant: first a standard configuration (without to consider equipments for CO2 emission reduction), and the second considering the implementation of a process of capture, storage and compression of carbon dioxide (CSC). The main objective of this analysis is to study and compare the differences in thermodynamic and ecological efficiencies (operating in both conditions) and the alterations in the electrical energy cost, in view of the installation of the CSC process.
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Kapetaki, Zoe. "Analysis of Integrated Gasification Combined Cycle power plants and process integration with pre-combustion carbon capture." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10519.
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Integrated Gasification Combined Cycle (IGCC) power plants have been considered as one of the best options for energy production in an environmental friendly manner. IGCC power plants are demonstrating better results, both in terms of plant performance and economics, when compared to a Pulverised Coal (PC) power plant with CO2 capture. The additional components required for an IGCC power plant when it is desired to operate in CO2 capture mode, give research potential with respect to an improved IGCC power plant performance. The IGCC power plant design framework studied and developed was based in DOE/NETL report and is presented. The conventional and CO2 capture IGCC power plants have been benchmarked in rigorous process flow diagrams developed using the commercial software Honeywell UniSim Design R400. As an essential part of the Innovative Gas Separations for Carbon Capture project (IGSCC EPSRC – EP/G062129/1) predictive simulation tools were produced to investigate the IGCC performance. The case studies considered include different gasification options for non-capture and carbon capture IGCCs, with a two stage Selexol process for the CO2 capture cases. Particular effort has been made to produce an accurate simulation component to describe the behaviour of the syngas in the Selexol solvent. The two stage Selexol configuration was investigated in detail and novel schemes are presented. No similar approaches have been reported in the literature, in terms of the proposed configuration and the capture efficiency. Moreover, innovative CO2 capture schemes incorporating combined units of physical absorption and membranes have been examined with respect to the power plant’s performance. In this thesis, contrary to other studies, all simulations cases have been conducted in unified flow diagrams. The results presented include overall investigations and can be a helpful tool for engineers and stakeholders in the decision making process.
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Cockcroft, Stephen John. "An evaluation of inertial motion capture technology for use in the analysis and optimization of road cycling kinematics." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6760.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011.ENGLISH ABSTRACT: Optical motion capture (Mocap) systems measure 3D human kinematics accurately and at high sample rates. One of the limitations of these systems is that they can only be used indoors. However, advances in inertial sensing have led to the development of inertial Mocap technology (IMCT). IMCT measures kinematics using inertial measurement units (IMUs) attached to a subject's body without the need for external sensors. It is thus completely portable which opens up new horizons for clinical Mocap. This study evaluates the use of IMCT for improving road cycling kinematics. Ten male sub-elite cyclists were recorded with an IMCT system for one minute while cycling at 2, 3.5 and 5.5 W.kg-1 on a stretch of road and on a stationary trainer. A benchmark test was also done where cycling kinematics was measured simultaneously with the IMCT and a gold-standard Vicon optical system. The first goal was to assess the feasibility of conducting field measurements of cycling kinematics. Magnetic analysis results showed that the IMUs near the pedals and handlebars experienced significant magnetic interference (up to 50% deviation in intensity) from ferrous materials in the road bicycles, causing significant errors in kinematic measurement. Therefore, it was found that the IMCT cannot measure accurate full-body kinematics with the subject on a road bicycle. However, the results of the benchmark test with the Vicon showed that the IMCT can still measure accurate hip (root mean square error (RMSE) < 1°), knee (RMSE < 3.5°) and ankle (RMSE < 3°) flexion using its Kinematic Coupling algorithm. The second goal was to determine whether there is a significant difference between road cycling kinematics captured on the road and in a laboratory. The outdoor flexion results were significantly different to the indoor results, especially for minimum flexion (P < 0.05 for all joints). Changes in rider kinematics between high and low power were also found to have significantly more variability on the road (R2 = 0.36, 0.61, 0.08) than on the trainer (R2 = 0.93, 0.89, 0.56) for the hip, knee and ankle joints respectively. These results bring into question the ecological validity of laboratory cycling. Lastly, applications of IMCT for optimizing cycling performance were to be identified. Several aspects of kinematic analysis and performance optimization using the IMCT were evaluated. It was determined that IMCT is most suited for use as a dynamic bicycle fitting tool for analysis of biomechanical efficiency, bilateral asymmetry and prevention of overuse injuries. Recommendations for future work include the elimination of the magnetic interference and integration of the IMCT data with kinetic measurements to develop an outdoor dynamic fitting protocol.
AFRIKAANSE OPSOMMING: Optiese bewegingswaarnemingstelsels (BWS) meet drie-dimensionele menslike kinematika met hoë akkuraatheid en teen hoë monstertempo's. Een van die nadele van BWS is dat hulle slegs binnenshuis gebruik kan word. Onlangse ontwikkelings in sensor tegnologie het egter gelei na die beskikbaarheid van traagheids-BWS-tegnologie (TBT). TBT gebruik traagheidsmetingseenhede (TMEs) wat aan 'n persoon se liggaam aangeheg kan word om die kinematika te verkry sonder enige eksterne sensore. TBT is dus volkome draagbaar, wat nuwe geleenthede skep vir kliniese bewingsanalises. Hierdie projek evalueer die gebruik van TBT vir die verbetering van fietsry kinematika. Tien kompeterende fietsryers (manlik) was getoets met 'n TBT terwyl hulle teen 2, 3.5 and 5.5 W.kg-1 gery het op 'n pad, en op 'n stilstaande oefenfietsraam. 'n Maatstaftoets was ook uitgevoer waar fietsry-kinematika gelyktydig met die TBT en die Vicon optiese BWS opgeneem was. Die eerste doel van die navorsing was om die moontlikheid te ondersoek of fietsryer kinematika op die pad gemeet kan word. Die resultate toon dat die ferro-magnetiese materiale wat in meeste padfietse voorkom, 'n beduidende magnetiese steuring (tot 50% afwyking in intensiteit) op die TMEs naby die pedale en handvatsels veroorsaak, wat lei tot aansienlike foute in die kinematiese metings. Gevolglik was dit gevind dat die TBT nie volle-liggaam kinematika op 'n fiets kan meet nie. Nogtans, het die resultate van die Vicon maatstaftoets bewys dat die TBT nog steeds akkurate heup (wortel van die gemiddelde kwadraad fout (WGKF) < 1°), knie (WGKF < 4°) en enkel (WGKF < 3°) fleksie kan meet met die “Kinematiese Koppeling” algoritme. Die tweede doel was om te bepaal of daar 'n beduidende verskil tussen die laboratorium en pad fietsry-kinematika is. Die buitelug fleksie data het beduidend verskil van die binnenshuise resultate, veral vir minimum fleksie (P < 0.05 vir alle gewrigte). Veranderinge in fietsryer kinematika tussen hoë en lae krag het ook beduidend meer variasie op die pad (R2 = 0.36, 0.61, 0.08) as op die oefenfietsraam (R2 = 0.93, 0.89, 0.56) vir die heup, knie en enkel gewrigte, onderskeidelik, gehad. Hierdie resultate bevraagteken die ekologiese geldigheid van kinematiese toetse op fietsryers in 'n laboratorium. 'n Laaste doel was om die toepassings van TBT vir die optimering van fietsry kinematika te ondersoek. 'n Verskeidenheid aspekte van die analise en verbetering van fietsry kinematika met die TBT word bespreek. Die gevolgtrekking is dat TBT geskik is vir gebruik as 'n dinamiese instrument vir die analise van biomeganiese doetreffendheid, bilaterale asimmetrie en die voorkoming van beserings. Aanbevelings vir toekomstige werk, sluit in die uitskakeling van die magnetiese inmenging, asook die integrasie van die TBT data met kinetiese metings.
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Chakravorty, Utshab. "STUDY OF CHARACTERIZATION OF SUBMICRON COAL PARTICLES DISPERSED IN AIR AND CAPTURE OF COAL PARTICLES BY WATER DROPS IN A SCRUBBING COLUMN." UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/16.
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Present day water spray based dust removal technologies do not effectively remove respirable submicron coal and silica dust particles in the underground coal mines causing Coal worker’s pneumoconiosis (CWP). The objective of this research was to study the electrostatic charges present in the airborne coal dust in order to develop efficient water spraying based dust removal technology where water drops charged using ionic compounds and surfactants would be used to capture the oppositely charged coal particles. In an experimental scrubbing column, coal particles dispersed in an air stream by a Fluidized Bed Aerosol Generator were captured by water drops sprayed by an atomizer. Characterization studies performed using an Aerodynamic Particle Sizer and Aerosol Electrometer showed that airborne coal particles have a significant amount of positive charge with an average of 140 elementary units of charge. The capture efficiencies of the water drops evaluated were found to be higher than those predicted by previously determined mathematical models. It was predicted that apart from the effects of Brownian diffusion, interception and impaction, the effect of Coulombic attraction was present and the charge of the water drops was predicted to be between - 2 x 10-6 C and -2 x 10-4 C.
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Karimi, Molan Safa. "Advanced Technologies for Detection of Cryptosporidum parvum in Drinking water: capture and detection using Microfluidic devices and Imaging Flow Cytometer." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210729.
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Protecting drinking water supplies from pathogens such as Cryptosporidium parvum is a major concern for water treatment plants worldwide. The sensitivity and specificity of current detection methods are largely determined by the effectiveness of the concentration and separation methods used. In this study, disposable microfluidic micromixers were fabricated to effectively isolate Cryptosporidium parvum Oocysts from water samples, while allowing direct observation of Oocysts captured in the device using high quality immunofluorescence microscopy. In parallel, quantitative analysis of the capture yield was carried out by analyzing the waste from the microfluidics outlet with an Imaging Flow Cytometer. At the optimal flow rate, capture efficiencies higher than 95% were achieved in spiked samples, suggesting that scaled microfluidic isolation and detection of Cryptosporidium parvum will provide a faster and more efficient detection method for Cryptosporidium compared to other available laboratory-scale technologies.
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Ebrahimzadeh, Edris. "Mitigating Transients and Azeotropes During Natural Gas Processing." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5880.
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Cryogenic carbon capture process can be used to efficiently eliminate CO2 emissions from fossil-fueled power plants. The energy-storing embodiment of cryogenic carbon capture (ES-CCC) integrates energy storage with cryogenic carbon capture and uses natural gas as a refrigerant. ES-CCC captures CO2 from slowly varying or steady-state sources even as it absorbs and replaces large amounts of energy on the grid for energy storage. These large transients occur in the LNG generation as the process moves through energy storing to energy recovery operations. Additionally, raw natural gas often includes CO2 that forms an azeotrope with ethane. Breaking this azeotrope and separating CO2 from other hydrocarbons to meet natural gas pipeline and liquefied natural gas (LNG) standards is very energy intensive. The purpose of this work is to (a) describe a dynamic heat exchanger that reduces the heat exchanger performance and efficiency losses experienced under transient conditions and (b) introduce an alternative extractive distillation system for CO2 separation from ethane that requires less capital and has a lower operating cost than the conventional system for the same purification. This investigation demonstrates theoretically and experimentally that the dynamic heat exchangers can absorb sudden and large changes in flow rates and other properties without compromising either the heat exchanger efficiency or creating thermal or other stresses. These heat exchangers play an essential role in the ES-CCC process. Designs for retrofitting existing heat exchangers and for replacing existing heat exchangers with new designs are both theoretically and experimentally tested. The ES-CCC process requires natural gas processing to meet pipeline and LNG standards in many applications, depending primarily on the CO2 content of locally available NG. The energy, cost, and dynamic response of such processing hinges primarily on the most difficult step, breaking the CO2-ethane azeotrope. This project proposes and analyzes an alternative process for breaking this azeotrope and a control scheme that dramatically improves the dynamic response of natural gas processing plants, including steady and transient control scheme and processing simulations. These contributions to the ES-CCC capture process all have much broader applications in many chemical and energy processes. These contributions to ES-CCC and other industrial processes improve energy efficiency and dynamic performance of many processes and are ready for larger scale demonstration.
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Lu, Hong. "Development of Calcium-Based Durable Sorbents with High Carbon Dioxide Uptake Efficiency at High Temperatures." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1239116430.
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Long, Henry A. III. "Development and Thermodynamic Analysis of an Integrated Mild/Partial Gasification Combined Cycle (IMPGC) Under Green and Brown Field Conditions With and Without Carbon Capture." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2538.
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Coal is a very prominent energy source in the world, but it is environmentally unattractive due to its high sulfur and ash content as well as its alleged contribution towards climate change, but it is affordable, abundant, and has high energy content. Thus, utilizing coal in a cleaner and more efficient way has become necessary. One promising clean coal technology involves fully gasifying coal into synthesis gas, cleaning it, and feeding it into a high-efficiency combined cycle, such as an Integrated Gasification Combined Cycle (IGCC). Inspired by the recent success of warn gas cleanup (WGCU), mild and partial gasification are proposed as less energy intensive options. This Integrated Mild/Partial Gasification Combined Cycle (IMPGC) could significantly save energy and improve efficiency. The objective of this study is to investigate the capabilities of IMPGC as both a new plant and a retrofit option for traditional coal power plants with and without carbon capture.
I MPGC relies on the principles of mild and partial gasification and the recently available WGGU technology with the following benefits: a.) completely negate the need for syngas cooling; b.) significantly reduce the energy needed to fully thermally crack the volatiles and completely gasify the char as in the IGCC system; c.) preserve the high chemical energy hydro-carbon bonds within the feedstock to allow more efficient combustion in the gas turbine; d.) reduce the size of gasifier and piping to reduce the costs; and e.) enable retrofitting of an old coal power plant by preserving the existing equipment.
The software used (Thermoflex®) was first validated with established cases from the U.S. Department of Energy. For new plants, the results show that IMPGC’s efficiency is 8 percentage points (20%) higher than IGCC, 8 points higher than a modern subcritical Rankine cycle, and 3-4 points higher than an ultra-supercritical (USC) cycle. When retrofitting older plants, a minimum improvement of over 4 points is predicted. When carbon capture is involved, IMPGC’s efficiency becomes 10 points better than a subcritical plant and 8 points better than a USC plant. Emissions wise, IMPGC is better than IGCC and much better than Rankine cycle plants.
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Yilmaz, Aslican Nazli. "Hydraulic Characteristics Of Tyrolean Weirs." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612780/index.pdf.
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Tyrolean type water-intake structures are widely used on mountain rivers to provide water to hydropower stations. The main concern encountered in these kinds of structures is the amount of water diverted from the main channel and sediment carried by this flow. The diverted flow should not be less than the design discharge of the hydropower station and the amount of the sediment entering the hydraulic system should be minimum. In this study a physical model of a Tyrolean weir was constructed at the Hydromechanics Laboratory and by varying the dimensions of the various components of this systemthe length, the inclination angle of the rack and the distance between the rack bars, the amount of water and sediment entering the system were measured for a wide range of discharges. The experiments were conducted in two stages. In the first stage the tests were made with only water, and in the second stage, water and sediment having different gradation were used. Applying dimensional analysis to the related parameters of the system dimensionless terms were defined for water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel flow.
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Sahiner, Halit. "Hydraulic Characteristics Of Tyrolean Weirs Having Steel Racks And Circular-perforated Entry." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614247/index.pdf.
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Tyrolean type water-intake structures are commonly used on mountain rivers to supply water to hydropower stations. The amount of water to be diverted from the main channel is the major concern in these kind of structures and should not be less than the design discharge. In this study a physical model of a Tyrolean type water-intake structure was built at the laboratory and the diverted flow from the main channel through the intake structure having steel racks and perforated plates of different types were measured. The experiments were conducted in two stages. In the first stage the tests were carried out with only steel racks having three different bar openings and slopes, and in the second stage, perforated screens of three different circular openings and screen slopes were used. Applying dimensional analysis to the related parameters of the system the dimensionless terms were defined for the water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel discharge.
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Li, Lei. "Fast Algorithms for Mining Co-evolving Time Series." Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/112.
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Time series data arise in many applications, from motion capture, environmental monitoring, temperatures in data centers, to physiological signals in health care. In the thesis, I will focus on the theme of learning and mining large collections of co-evolving sequences, with the goal of developing fast algorithms for finding patterns, summarization, and anomalies. In particular, this thesis will answer the following recurring challenges for time series:
1. Forecasting and imputation: How to do forecasting and to recover missing values in time series data?
2. Pattern discovery and summarization: How to identify the patterns in the time sequences that would facilitate further mining tasks such as compression, segmentation and anomaly detection?
3. Similarity and feature extraction: How to extract compact and meaningful features from multiple co-evolving sequences that will enable better clustering and similarity queries of time series?
4. Scale up: How to handle large data sets on modern computing hardware?
We develop models to mine time series with missing values, to extract compact representation from time sequences, to segment the sequences, and to do forecasting. For large scale data, we propose algorithms for learning time series models, in particular, including Linear Dynamical Systems (LDS) and Hidden Markov Models (HMM). We also develop a distributed algorithm for finding patterns in large web-click streams. Our thesis will present special models and algorithms that incorporate domain knowledge. For motion capture, we will describe the natural motion stitching and occlusion filling for human motion. In particular, we provide a metric for evaluating the naturalness of motion stitching, based which we choose the best stitching. Thanks to domain knowledge (body structure and bone lengths), our algorithm is capable of recovering occlusions in mocap sequences, better in accuracy and longer in missing period. We also develop an algorithm for forecasting thermal conditions in a warehouse-sized data center. The forecast will help us control and manage the data center in a energy-efficient way, which can save a significant percentage of electric power consumption in data centers.
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Dépée, Alexis. "Etude expérimentale et théorique des mécanismes microphysiques mis en jeu dans la capture des aérosols radioactifs par les nuages." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC057.
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Les particules atmosphériques sont un sujet d’importance dans plusieurs couches de la société. Leur présence dans l’atmosphère est aussi bien une problématique météorologique et climatique qu’un enjeu de santé publique, notamment de par l’accroissement des maladies cardiovasculaires. En particulier, les particules radioactives émises dans l’atmosphère à la suite d’un accident nucléaire peuvent polluer les écosystèmes durant plusieurs années. Le récent accident du Centre Nucléaire de Production d’Électricité de Fukushima Daiichi en 2011 nous rappelle que, même aujourd’hui, le risque zéro n’existe pas. À la suite d’une émission dans l’atmosphère, les particules nanométriques diffusent et s’agglomèrent alors que les particules de plusieurs micromètres sédimentent. Les tailles intermédiaires vont, quant à elles, pouvoir être transportées à l’échelle globale dont le mécanisme principal de rabattement au sol provient des interactions avec les nuages et les précipitations. Afin d’améliorer la connaissance de la contamination des sols consécutive à de tels accidents, la compréhension de la capture des aérosols par les nuages est alors essentielle. Dans ce but, un modèle microphysique est implémenté dans ce travail, considérant les mécanismes microphysiques qui interviennent dans la capture des aérosols par des gouttes de nuage, notamment les forces électrostatiques dès lors que les radionucléides ont pour propriété de fortement se charger. Des mesures en laboratoire sont alors réalisées à l’aide de In-CASE (In-Cloud Aerosols Scavenging Experiment), expérience conçue dans ce travail, afin de comparer le modèle développé aux observations, et ce, toujours à une échelle microphysique où les paramètres d’influence régissant la capture au sein du nuage sont contrôlés. Par ailleurs, des systèmes de charge des particules et des gouttes sont conçus pour soigneusement maîtriser les charges électriques, tandis que l’humidité relative est précisément pilotée. Les nouvelles connaissances de la capture des particules par des gouttes de nuage qui en découlent, concernant entre autres les effets électrostatiques, sont ensuite incorporées au modèle de nuage convectif DESCAM (Detailed SCAvenging Model). Ce modèle à microphysique détaillée décrit un nuage de sa formation jusqu’aux précipitations, permettant d’étudier l’impact des nouvelles données sur le rabattement des particules à méso-échelle. De plus, des modifications sont apportées à DESCAM pour élargir l’étude aux nuages stratiformes qui constituent en France, la majorité des précipitations. À terme, cette étude ouvre la voie à l’amélioration de la modélisation du rabattement atmosphérique des particules, et notamment à la contamination des sols dans les modèles de crise de l’Institut de Radioprotection et de Sûreté NucléaireAtmospheric particles are a key topic in many social issues. Their presence in this atmosphere is a meteorological and climatic subject, as well as a public health concern since these particles are correlated with the increase of cardiovascular diseases. Specially, radioactive particles emitted as a result of a nuclear accident can jeopardise ecosystems for decades. The recent accident at the Fukushima Daiichi’s nuclear power plant in 2011 reminds us that the risk, even extremely unlikely, exists.After a release of nuclear material in the atmosphere, nanometric particles diffuse and coagulate, while micrometric particles settle due to gravity. Nevertheless, the intermediate size particles can be transported at a global scale when the main mechanism involved in their scavenging comes from the interaction with clouds and their precipitations. To enhance the ground contamination knowledge after such accidental releases, the understanding of the particle in-cloud collection is thus essential. For this purpose, a microphysical model is implemented in this work, including the whole microphysical mechanisms acting on the particle collection by cloud droplets like the electrostatic forces since radionuclides are well-known to become significantly charged. Laboratory measurements are then conducted through In-CASE (In-Cloud Aerosols Scavenging Experiment), a novel experiment built in this work, to get comparisons between modelling and observations, once again at a microphysical scale where every parameter influencing the particle in-cloud collection is controlled. Furthermore, two systems to electrically charge particles and droplets are constructed to set the electric charges carefully while the relative humidity level is also regulated. These new research results related to the particle collection by cloud droplets following the electrostatic forces, among others effects, are thus incorporated into the convective cloud model DESCAM (Detailed SCAvenging Model). This detailed microphysical model describes a cloud from its formation to the precipitations, allowing the study at a meso-scale of the impact of the new data on the particle scavenging. Moreover, some changes are made in DESCAM to expand the study to stratiform clouds since the major part of the French precipitations come from the stratiform ones. Finally, this work paves the way for the enhancement of the atmospheric particle scavenging modelling, including the ground contamination in the crisis model used by the French Institute in Radiological Protection and Nuclear Safety
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Cartelle, Saball Julia. "Grain yield determinants in a traditional and a modern wheat cultivar under a wide range of conditions in a Mediterranean region: source-sink relationships, components, resource capture and use efficiencies." Doctoral thesis, Universitat de Lleida, 2015. http://hdl.handle.net/10803/386572.
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El principal objectiu de la tesi va ser avaluar els determinants fisiològics del rendiment
d'un cultivar de blat tradicional i un modern en resposta a diferents disponibilitats d'aigua i
nitrogen en condicions mediterrànies. Es pot concloure que el cultivar tradicional no va superar
clarament en rendiment al modern sota condicions més estressants, ni el cultivar modern va
superar al seu contrapart tradicional quan les condicions van ser més favorables. En relació als
dos components numèrics del rendiment, el nombre de grans per unitat de superfície va ser el
principal component explicant la seva variació i el pes del gra va ser limitat per destí durant
l'ompliment de gra. L'ús del nitrogen i l'aigua i les seves eficiències van estar relacionades amb
les variacions del rendiment per a tots dos cultivars. L'absorció de nitrogen va ocórrer
principalment durant pre-antesi, mentre que la concentració de nitrogen en gra va estar generada
majorment per translocació. El cultivar modern va presentar un sistema radicular més gran que el
tradicional. No obstant això, aquesta superioritat no es va traduir en diferències consistents en
rendiment o eficiència en l'ús de recursos.El principal objetivo de la tesis fue evaluar los determinantes fisiológicos del rendimiento de un cultivar de trigo tradicional y uno moderno en respuesta a diferentes disponibilidades de agua y nitrógeno en condiciones mediterráneas. Se puede concluir que el cultivar tradicional no superó claramente en rendimiento al moderno bajo condiciones más estresantes, ni el cultivar moderno superó a su contraparte tradicional cuando las condiciones fueron más favorables. En relación a los dos componentes numéricos del rendimiento, el número de granos por unidad de superficie fue el principal componente explicando su variación y el peso del grano fue limitado por sumidero durante el llenado de grano. El uso del nitrógeno y el agua y sus eficiencias estuvieron relacionadas con las variaciones del rendimiento para ambos cultivares. La absorción de nitrógeno ocurrió principalmente durante pre-antesis, mientras que la concentración de nitrógeno en grano estuvo generada mayormente por translocación. El cultivar moderno presentó un sistema radicular mayor que el tradicional. Sin embargo, esta superioridad no se tradujo en diferencias consistentes en rendimiento o eficiencia en el uso de recursos.
The main objective of the thesis was to assess the physiological grain yield determinants of a traditional and a modern wheat cultivar in response to different water and nitrogen availabilities under Mediterranean conditions. It can be concluded that the traditional cultivar did not consistently outyield the modern one under more stressful conditions, nor did the modern cultivar outyield its older counterpart whenever the conditions were less stressful. Concerning the two major numerical components of grain yield, grain number per unit land area was the main component explaining its variation and grain weight was sink-limited during grain filling. N and water use and their efficiencies were related to variations in grain yield for both cultivars. N uptake occurred mainly along pre-anthesis, while grain N concentration was generated chiefly by translocation. The modern cultivar presented a larger root system than the traditional one. Nevertheless this superiority did not translate in consistent differences in grain yield or resource use efficiencies.
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Rump, Martin [Verfasser]. "Efficient Capture of Multispectral Reflectance of Complex Surfaces / Martin Rump." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1224270487/34.
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Kundu, Titir. "Exploring Capture Effect for Efficient Channel Assignment in Wireless Sensor Network." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439309020.
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Nobis, Frank. "Charakterisierung von a-Si:H/c-Si-Heterokontakten und dünnen Schichten aus hydrogenisiertem amorphem Silizium, hergestellt mittels gepulstem DC-Magnetronsputtern." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-127840.
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Dünne Schichten aus hydrogenisiertem amorphem Silizium a-Si:H spielen für die Photovoltaik eine wichtige Rolle. Einerseits kommt für die Dünnschicht-Photovoltaik unterschiedlich dotiertes a-Si:H in den Schichten einer p-i-n-Solarzelle zur Anwendung, andererseits stellen Heterokontakt-Solarzellen aus amorphem und kristallinem Silizium (a-Si:H/c-Si) wegen ihres hohen Wirkungsgrades derzeit ein sehr aktuelles Forschungsthema dar.
Die Abscheidung der a-Si:H-Schichten im Rahmen dieser Arbeit erfolgt mit der Methode des Magnetronsputterns (Kathodenzerstäubung). Dieses für die in-line-Beschichtung etablierte Verfahren wird speziell für die Photovoltaik noch nicht in industriellem Maßstab eingesetzt (lediglich für transparente leitfähige Oxide TCO). Insbesondere existiert nur eine geringe Zahl von Veröffentlichungen zu Heterokontakten, welche mittels Magnetronsputtern hergestellt wurden. Ein Schwerpunkt der vorliegenden Arbeit ist daher die Herstellung sowie Charakterisierung solcher Heterokontakte unter dem Aspekt variierter Abscheide- und Prozessparameter (Substrattemperatur, Wasserstoffflussrate, Ionenbeschuss). Das für das Sputtern erforderliche Plasma wird mit einer im Mittelfrequenzbereich gepulsten Gleichspannung angeregt. Ein dadurch mehr oder weniger ausgeprägter Ionenbeschuss der wachsenden Schichten in Abhängigkeit der Pulsparameter wird hier analysiert. Die Charakterisierung der Heterokontakte erfolgt hauptsächlich anhand deren Strom-Spannung-Kennlinien, welche auch bei variierter Temperatur gemessen werden. Erzielte Gleichrichtungsverhältnisse um 10000:1 sowie Diodenidealitätsfaktoren η ≈ 1,3 kennzeichnen (p)a-Si:H/(n)c-Si-Heterokontakte mit den besten halbleiterphysikalischen Eigenschaften. Bei zu schwacher Schichthydrogenisierung wurde ein Ladungstransportmechanismus nachgewiesen, welcher in der Literatur als multi-tunneling capture-emission MTCE bekannt ist. Eine erhöhte Hydrogenisierung unterdrückt diesen Mechanismus nahezu vollständig. Durch Abscheidung unterschiedlich stark bordotierter a-Si:H-Schichten wird außerdem die Dotiereffizienz beurteilt. Hohe Werte sind bei amorphen Halbleitern im Allgemeinen schwer zu erreichen. Die mit stärkerer Dotierung erhöhte Gleichrichterwirkung lieferte hier ein Indiz für eine nachweisbare Dotiereffizienz.
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Nimo, Antwi [Verfasser], and Leonhard M. [Akademischer Betreuer] Reindl. "Efficient voltage transformation of wirelessly captured ambient electromagnetic power." Freiburg : Universität, 2015. http://d-nb.info/1179075226/34.
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Nöll, Tobias [Verfasser]. "Efficient Representation of Captured Geometry and Reflectance / Tobias Nöll." München : Verlag Dr. Hut, 2015. http://d-nb.info/1079768955/34.
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Nguyen, Nhan Thanh. "Programmer le développement soutenable dans un pays en voie de développement: Une optimisation sociale du secteur électrique au Vietnam." Phd thesis, Ecole des Hautes Etudes en Sciences Sociales (EHESS), 2011. http://tel.archives-ouvertes.fr/tel-00593573.
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Au cœur de cette thèse réside l'application des méthodes d'optimisation et d'études empiriques pour traiter des questions de développement durable dans le secteur de l'électricité du Vietnam pour les 30 prochaines années. On examine les moyens des options énergétiques durables pour le secteur de l'électricité. La thèse s'organise en deux parties. (i) Dans la première partie, nous développons le modèle " bottom-up " de planification intégrée des ressources (IRP) pour fournir une évaluation plus exhaustive de l'état actuel et des perspectives d'avenir pour le secteur de l'électricité du Vietnam dans les trois prochaines décennies. Puis, en utilisant une analyse comparative et une analyse de la vulnérabilité qui est basée sur la simulation IRP, nous analysons les vulnérabilités auxquelles le développement du secteur devra faire face, en termes de dimensions économiques et socio-environnementales. Nous avons en outre développé le modèle IRP, représentant les coûts marginaux de réduction des émissions de carbone de manière réaliste en tenant compte des valeurs non nulles de carbone et de limitation des émissions de carbone, afin de simuler des options d'approvisionnement énergétique soutenables pour le secteur de l'énergie. (ii) Dans la deuxième partie, nous étudions les principaux obstacles contre une adoption plus large des énergies soutenables à l'aide d'enquêtes formelles parmi les experts nationaux. Ensuite, nous utilisons une approche d'analyse empirique pour examiner les différents outils politiques appropriés, y compris des instruments d'incitation / régimes et la réforme du secteur pour une telle durabilité du secteur de l'énergie. Pour la fin, nous analysons l'accès aux sources de financement possibles pour le développement durable dans le secteur de l'électricité du Vietnam.
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Winkler, Martin. "Vliv polohy zesíleného štěrbinového sacího nástavce nad pracovním stolem na účinnost odsávání." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230424.
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The present thesis explores the reinforced exhaust slot system above work table. Its objective was to measure the capture efficiency in front of the suction extension in various elevation levels of the workbench, taking into consideration four mobility ratios, while in the first case we performed traditional suction. The thesis also presents the results of capture efficiency measurements recorded in figures and tables of measured values. The conclusion analyzes the uncertainty in performed measurements.
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Cronje, Lizl. "Surface modification of styrene maleic anhydride nanofibers for efficient capture of Mycobacterium tuberculosis." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71923.
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Thesis (PhD)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Tuberculosis (TB) is a major cause of morbidity and mortality across the world, affecting adults and children. Children infected with TB differ from adults, as their immunological and patho-physiological response to the disease is different. Although there are a variety of tests available for TB diagnosis, they have limitations when used to diagnose paediatric TB. Children are also unable to generate sputum spontaneously when required for the use in culture or microscopy as diagnostic method. Children however do produce sputum, containing the TB bacilli, which they swallow. If the TB bacilli can therefore be retrieved from the stomach and tested, TB can be diagnosed using gastric samples. In this thesis, a variety of styrene maleimide copolymer (SMI) derivatives were prepared as potential M. tuberculosis-capturing platforms. This was done by modifying poly(styrene-co-maleic anhydride) (SMA) with a variety of primary amine compounds, selected based on possible chemical interactions with the M. tuberculosis cell wall. All the prepared copolymer derivatives were electrospun into nanofibrous mats using the single needle electrospinning technique to yield SMI nanofibers, functionalized with different compounds. Some of the functionalized SMI nanofibers were prepared by surface-functionalization of the polymer nanofibers after electrospinning and some by modification of the polymer before electrospinning. Affinity studies were conducted at neutral and low pH between the different functionalized SMI nanofibers and two mycobacterium strains, namely the bacillus Calmette-Guérin strain of Mycobacterium bovis (BCG) and M. tuberculosis, to evaluate the surfaces of the modified SMI nanofibers as mycobacterium-capturing platforms. The successful capture of BCG onto the surfaces of the various functionalized nanofibers was confirmed by SEM and fluorescence microscopy (FM). Analysis of the SEM and FM images indicated that the SMI nanofibers, functionalized with a C12 aliphatic quaternary ammonium moiety (SMI-qC12), captured BCG the most effectively through a combination of ionic and hydrophobic interaction. Concentration and time studies revealed that the extent of this interaction was dependent on incubation time and concentration of BCG. The affinity studies with BCG also concluded that the polymer used for the nanofibrous-capturing platform should not be too hydrophobic in character as this caused poor wetting of the functionalized nanofibers, thus preventing close contact with the mycobacteria and a reduction in the capture effectivity of the polymer nanofibers. The successful capture of M. tuberculosis onto the SMI-qC12 nanofibrous surface was confirmed by FM, light microscopy (LM) and polymerase chain reaction (PCR). The extent of this interaction was dependent on the concentration of M. tuberculosis. The detection of M. tuberculosis using FM and LM as detection methods was simplified by the tendency of M. tuberculosis to clump together in clusters on the hydrophobic surface of the SMI-qC12 nanofibers. As a result of this clustering, FM and LM were therefore regarded as feasible detection methods to image M. tuberculosis on the surface of the SMI-qC12 nanofibers, even at relatively low concentration of M. tuberculosis.
AFRIKAANSE OPSOMMING: Tuberkulose (TB) is 'n groot oorsaak van morbiditeit en mortaliteit regoor die wêreld en affekteer volwassenes en kinders. Kinders wat met TB geïnfekteer is, se immunologiese en patofisiologiese reaksie op die siekte verskil van die van volwassenes en dit het belangrike implikasies vir die diagnose van TB in kinders. Alhoewel daar 'n verskeidenheid van toetse beskikbaar is vir die diagnose van TB, het hulle beperkings wanneer dit gebruik word om pediatriese TB te diagnoseer. Kinders kan ook nie spontaan sputum produseer as dit nodig is vir die gebruik in kultuur of mikroskopie as diagnostiese metode. Kinders produseer egter wel sputum, wat die TB basille bevat, wat hulle dan insluk. As die TB basille uit die maag versamel kan word en getoets kan word, kan TB gediagnoseer word met behulp van maag monsters. In hierdie tesis is 'n verskeidenheid van stireen maleimied kopolimeer (SMI) afgeleides voorberei as potensiële Mycobacterium tuberkulose (Mtb)-vaslegging platforms. Dit is gedoen deur die modifikasie van poli(stireen-ko-maleïen anhidried) (SMA) met 'n verskeidenheid primêre amien verbindings as oppervlak-funksionaliseringsagente. Hierdie primêre amien verbindings is gekies op grond van moontlike chemiese interaksies met die Mtb selwand. Al die voorbereide kopolimeer afgeleides is elektrogespin in nanoveselagtige matte met behulp van die enkel-naald elektrospin tegniek om SMI nanovesels te lewer wat gefunksionaliseer is met verskillende verbindings. Sommige van die gefunksionaliseerde SMI nanovesels is berei deur oppervlak-funksionalisering van die polimeer nanovesels na elektrospin, en sommige deur die modifikasie van die polimeer voor elektrospin. Affiniteitstudies is uitgevoer, by neutrale en lae pH, tussen die verskillende gefunksionaliseerde SMI nanovesels en twee mikobakterium rasse, naamlik die basillus Calmette-Guérin ras van Mycobacterium bovis (BCG) en M. tuberculosis, om die oppervlaktes van die gewysigde SMI nanovesels te evalueer as mikobakterium-vaslegging platforms. Ontleding van die SEM en FM beelde het aangedui dat die SMI nanovesels, gefunksionaliseer met 'n C12 alifatiese kwaternêre ammonium groep (SMI-qC12), BCG die doeltreffendste vasgevang het deur 'n kombinasie van ioniese en hidrofobiese interaksie. Konsentrasie- en tydstudies tussen BCG en SMI-qC12 het aangedui dat die omvang van hierdie interaksie afhanklik is van inkubasietyd en konsentrasie van BCG. Die affiniteitstudies met BCG het ook aangedui dat die polimeer wat gebruik word vir die nanoveselagtige-vaslegging platform nie te hidrofobiese moet wees nie, aangesien dit swak benatting van die gefunksionaliseerde nanovesels veroorsaak, en dus noue kontak met die mikobakterieë voorkom met ʼn gevolglike vermindering in die vasvang-effektiwiteit van die polimeer nanovesels. Die suksesvolle vasvang van M. tuberculosis op die SMI-qC12 nanovesels is bevestig deur FM, lig mikroskopie (LM) en polimerase kettingreaksie (PKR). Die opsporing van Mtb deur die gebruik van FM en LM as opsporingmetodes is vergemaklik deur die tendens van Mtb om in groepies saam te pak op die hidrofobiese oppervlak van die SMI-qC12 nanovesels. As gevolg van hierdie groepering, is FM en LM dus haalbare opsporingmetodes om M. tuberculosis op die oppervlak van die SMI-qC12 nanovesels waar te neem, selfs by relatief lae konsentrasie van M. tuberculosis.
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Rault, Tifenn. "Energy-efficiency in wireless sensor networks." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2228/document.
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Dans cette thèse, nous avons proposé des solutions originales et performantes pour l’économie d’énergie dans les réseaux de capteurs sans fil (RCSF). Ces contributions s'organisent autour de deux grands axes : les réseaux de capteurs génériques et les réseaux de capteurs sans fil dédiés aux applications santé. Dans un premier temps, nous avons réalisé un état-de-l’art des mécanismes d'économie d’énergie pour les RCSF. Nous avons ensuite proposé deux solutions originales : la première optimise le déplacement d’une station de base, ainsi que la façon dont les données sont stockées dans les capteurs et routées vers le puit mobile ; la seconde optimise le déploiement de chargeurs mobiles, qui une fois dans le réseau permettent de satisfaire la demande en énergie des nœuds via la transmission d’énergie sans fil sur plusieurs sauts. Dans un second temps, nous nous sommes intéressés plus particulièrement aux applications des RCSF pour la supervision de patients à distance. Nous avons introduit une nouvelle classification des techniques économes en énergie adaptées à la spécificité de ces applications santé. Nous avons ensuite proposé une nouvelle architecture pour la supervision de patient à distance à l’aide de capteurs sans fil qui permet de prolonger la durée de vie des capteurs et de la station de base. Cette solution prend en compte l’environnement du patient et l’hétérogénéité des appareils. Nos résultats montrent que la durée de vie des réseaux de capteurs sans fil peut être étendue en utilisant les différentes stratégies proposées. L’efficacité de ces approches a été confirmée à l’aide de nombreuses expérimentations numériques et simulationsIn this thesis, we propose new strategies for energy conservation in wireless sensor networks, so that the operational time of these networks can be extended. The work can be divided into two main focus area, namely general wireless sensor networks, and healthcareoriented wearable sensor networks. In the first part of this thesis we provide a comprehensive survey of the existing energy-efficient mechanisms. Then, we propose two new solutions: the first one optimizes the displacement of a mobile base station as well as buffer usage and data routing at sensor nodes; the second one optimizes the deployment of wireless chargers in the network to satisfy the energy demand of the sensors. The second part of this thesis is dedicated to healthcare application where wearable sensors are used to remotely supervise a patient. We begin with a state-of-the-art of the energy-efficient techniques existing in the literature. We then introduce a new energy-efficient architecture that allows to optimize the lifetime of both the sensor and the base station. This is a context-aware solution that takes into consideration heterogeneous devices. Our results show that the lifetime of the sensor networks can be extended using the proposed strategies. All the results obtained are supported by numerical experiments and extensive simulations
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Walsh, Mark Gordon. "Evaluation of dietary carbohydrate utilization by captive sablefish (Anoplopoma fimbria)." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30429.
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Carbohydrates have variable digestibilities and metabolizable energy values in carnivorous fish. Simple sugars are generally more digestible than complex polysaccharides, and low levels of dietary carbohydrate may contribute more metabolizable energy than high levels. Two experiments were conducted to study the effects of dietary level and processing treatment of wheat starch on the digestibility of diets fed to sablefish (Anoplopoma fimbria), in different regions of the digestive tract. Moreover, an experiment was undertaken to determine if the dietary concentration of an indigestible external marker (chromic oxide) influenced its motility, relative to other ingredients in the ingesta, as it passed through the digestive tract. Lastly, a growth experiment was undertaken to compare the performance of sablefish fed formulated diets containing one of two levels of carbohydrate to that of fish fed a natural fish diet. The gastric evacuation of a formulated and a natural diet were also investigated.
Apparent digestibility values for the nutrients in a formulated diet (containing 44.4% cooked wheat and 0.1% chromic oxide) fed to sablefish were noted to increase progressively from the anterior to the posterior regions of the intestinal tract. Within each region of the gut, the apparent digestibility values for most nutrients declined over three sample periods. Carbohydrate (nitrogen-free extract) digestibility down to the distal section of the intestine ranged from 51.0 to 82.8%.
An experiment designed to assess the effect of carbohydrate treatment on the digestibility of four isonitrogenous, isocaloric diets met with partial failure. It was determined that the 1.0% chromic oxide marker flowed at a differential rate to the rest of the ingesta in the digestive tract, which violated the criteria for an effective marker. Consequently, diet digestibility was not determined in this experiment. Hepatic glycogen levels in fish receiving the dietary treatments were compared, and these values were used to estimate the relative availability (digestibility) of carbohydrate from the respective diets. According to this index, the sequence for digestibility was as follows: pregelatinized starch > cooked wheat > pregelatinized starch/cooked wheat > unprocessed wheat.
Differential movement of chromic oxide relative to other ingesta was observed in sablefish fed on alternate days regardless of the dietary concentration of the indigestible marker (0.1 or 1.0%). It was surmised that the feeding protocol established the circumstances from which marker 'streaming' was observed in the results. Differential transport of Cr₂O₃ through the gut by ingested seawater was suggested as a possible mechanism for the phenomenon.
Sablefish fed a natural fish diet had the highest growth rates, condition factors, liver lipid levels and the lowest feed conversion ratios and liver glycogen levels. Sablefish fed a diet containing 22.2% cooked wheat had a higher growth rate, condition factor, and a lower food conversion ratio, than those fed a diet containing 44.4% cooked wheat. Ingestion of the 44.4% cooked wheat diet resulted in the highest values for liver glycogen and hepatosomatic index.
It was concluded that sablefish have a limited ability to metabolically utilize digestible carbohydrate and that most of the dietary non-protein energy should originate from high quality lipid for maximum protein sparing.Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate
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Shiflett, Sheri. "PHYSIOLOGICAL MECHANISMS OF SHRUB ENCROACHMENT: LINKING ENHANCED HYDRAULIC CAPACITY TO EFFICIENT LIGHT CAPTURE AND PROCESSING." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3208.
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Woody plant expansion has been documented for decades in many different ecosystems, often due to anthropogenic disturbances to the environment and yielding vast changes in ecosystem functioning. While causes and consequences of woody expansion have been well documented, few studies have investigated functional traits of woody species that promote rapid expansion in range. My objective was to determine if hydraulic efficiency confers enhanced photosynthetic efficiency so that functional traits representing light and water use may be possible mechanisms facilitating woody encroachment into grasslands and forest understories. I quantified leaf-level light environment, photosynthetic activity, and hydraulic characteristics of three sympatric broadleaf evergreens of varying leaf life span (Ilex opaca, Kalmia latifolia, and Myrica cerifera) in a deciduous forest understory to understand seasonal intra- and interspecific ranges of broadleaf evergreen physiology. Additionally, I investigated the effects of age on physiological efficiency of M. cerifera across a chronosequence (i.e., space for time substitution) of shrub thicket development in order to understand possible age-related physiological mechanisms facilitating shrub expansion. Lastly, I determined functional traits and resulting physiology that contribute to rapid expansion and thicket formation of an invasive, deciduous, N-fixing shrub, Elaeagnus umbellata, and a native, evergreen, N-fixing shrub M. cerifera. When compared to co-occurring evergreen species, electron transport rate (ETR) of M. cerifera was nearly double that of I. opaca or K. latifolia in summer. Photosynthetic capacity was positively related to hydraulic capacity among understory evergreens. Furthermore, photosynthetic and hydraulic efficiency of M. cerifera remained consistent despite considerable differences in thicket age and development. Both similar and contrasting functional traits of E. umbellata and M. cerifera allowed for enhanced light capture and water movement, and reductions in subcanopy light penetration. Enhanced hydraulic and photosynthetic efficiency relative to co-occurring species contributes to rapid range expansion and thicket formation by promoting enhanced productivity and limiting successful colonization of other species. My results indicate that there may be suites of functional traits linked to expansive success and thicket-formation, yet differences in functional traits between native and invasive species represent alternative strategies leading to rapid growth and thicketization.
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Knieschewski, Arno [Verfasser]. "Energy efficiency rating of cooking fume extractors based on captured and filtered oil mist / Arno Knieschewski." Düren : Shaker, 2020. http://d-nb.info/1215461844/34.
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Su, Po-Chang. "REAL-TIME CAPTURE AND RENDERING OF PHYSICAL SCENE WITH AN EFFICIENTLY CALIBRATED RGB-D CAMERA NETWORK." UKnowledge, 2017. https://uknowledge.uky.edu/ece_etds/110.
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From object tracking to 3D reconstruction, RGB-Depth (RGB-D) camera networks play an increasingly important role in many vision and graphics applications. With the recent explosive growth of Augmented Reality (AR) and Virtual Reality (VR) platforms, utilizing camera RGB-D camera networks to capture and render dynamic physical space can enhance immersive experiences for users. To maximize coverage and minimize costs, practical applications often use a small number of RGB-D cameras and sparsely place them around the environment for data capturing. While sparse color camera networks have been studied for decades, the problems of extrinsic calibration of and rendering with sparse RGB-D camera networks are less well understood. Extrinsic calibration is difficult because of inappropriate RGB-D camera models and lack of shared scene features. Due to the significant camera noise and sparse coverage of the scene, the quality of rendering 3D point clouds is much lower compared with synthetic models. Adding virtual objects whose rendering depend on the physical environment such as those with reflective surfaces further complicate the rendering pipeline.
In this dissertation, I propose novel solutions to tackle these challenges faced by RGB-D camera systems. First, I propose a novel extrinsic calibration algorithm that can accurately and rapidly calibrate the geometric relationships across an arbitrary number of RGB-D cameras on a network. Second, I propose a novel rendering pipeline that can capture and render, in real-time, dynamic scenes in the presence of arbitrary-shaped reflective virtual objects. Third, I have demonstrated a teleportation application that uses the proposed system to merge two geographically separated 3D captured scenes into the same reconstructed environment.
To provide a fast and robust calibration for a sparse RGB-D camera network, first, the correspondences between different camera views are established by using a spherical calibration object. We show that this approach outperforms other techniques based on planar calibration objects. Second, instead of modeling camera extrinsic using rigid transformation that is optimal only for pinhole cameras, different view transformation functions including rigid transformation, polynomial transformation, and manifold regression are systematically tested to determine the most robust mapping that generalizes well to unseen data. Third, the celebrated bundle adjustment procedure is reformulated to minimize the global 3D projection error so as to fine-tune the initial estimates. To achieve a realistic mirror rendering, a robust eye detector is used to identify the viewer's 3D location and render the reflective scene accordingly. The limited field of view obtained from a single camera is overcome by our calibrated RGB-D camera network system that is scalable to capture an arbitrarily large environment. The rendering is accomplished by raytracing light rays from the viewpoint to the scene reflected by the virtual curved surface. To the best of our knowledge, the proposed system is the first to render reflective dynamic scenes from real 3D data in large environments. Our scalable client-server architecture is computationally efficient - the calibration of a camera network system, including data capture, can be done in minutes using only commodity PCs.
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Issa, Nader. "Modes and propagation in microstructured optical fibres." University of Sydney. Physics and Optical Fibre Technology Centre, 2005. http://hdl.handle.net/2123/613.
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Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions imposed outside the microstructure. This yields the leaky modes supported by the fibre. The boundary conditions are achieved exactly using a novel refinement scheme called the Adjustable Boundary Condition (ABC) method. Two implementations are programmed and their computational efficiencies are compared. Both use an azimuthal Fourier decomposition, but radially, a finite difference scheme is shown to be more efficient than a basis function expansion. The properties of the ABC method are then predicted theoretically using an original approach. It shows that the method is highly efficient, robust, automated and generally applicable to any implementation or to other radiating problems. A theoretical framework for the properties of modes in MOFs is also presented. It includes the use of the Bloch-Floquet theorem to provide a simpler and more efficient way to exploit microstructure symmetry. A new, but brief study of the modal birefringence properties in straight and spun fibres is also included. The theoretical and numerical tools are then applied to the study of polymer MOFs. Three types of fibres are numerically studied, fabricated and characterised. Each is of contemporary interest. Firstly, fabrication of the first MOFs with uniformly oriented elliptical holes is presented. A high degree of hole ellipticity is achieved using a simple technique relying on hole deformation during fibre draw. Both form and stress-optic birefringence are characterized over a broad scaled-wavelength range, which shows excellent agreement with numerical modelling. Secondly, an analysis of leaky modes in real air core MOFs, fabricated specifically for photonic band gap guidance, is then used to identify alternative guiding mechanisms. The supported leaky modes exhibit properties closely matching a simple hollow waveguide, weakly influenced by the surrounding microstructure. The analysis gives a quantitative determination of the wavelength dependent confinement loss of these modes and illustrates a mechanism not photonic band gap in origin by which colouration can be observed in such fibres. Finally, highly multimode MOFs (also called `air-clad' fibres) that have much wider light acceptance angles than conventional fibres are studied. An original and accurate method is presented for determining the numerical aperture of such fibres using leaky modes. The dependence on length, wavelength and various microstructure dimensions are evaluated for the first time for a class of fibres. These results show excellent agreement with published measurements on similar fibres and verify that bridge thicknesses much smaller than the wavelength are required for exceptionally high numerical apertures. The influence of multiple layers of holes on the numerical aperture and capture efficiency are then presented. It shows that a substantial increase in both these parameters can be achieved for some bridge thicknesses. Simple heuristic expressions for these quantities are given, which are based on the physical insight provided by the full numerical models. The work is then supported by the first fabrication attempts of large-core polymer MOFs with thin supporting bridges. These fibres exhibit relatively high numerical apertures and show good agreement with theoretical expectations over a very wide scaled-wavelength range.
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Beck, J. H. "Efficient targeted optimisation for the design of pressure swing adsorption systems for CO2 capture in power plants." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1429983/.
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Pressure swing adsorption (PSA) is a cyclic adsorption process for gas separation and purification, and can be used in a variety of industrial applications, for example, hydrogen purification and dehydration. PSA is, due to its low operational cost and its ability to efficiently separate CO2 from flue gas, a promising candidate for post-combustion carbon capture in power plants, which is an important link in the Carbon Capture and Storage technology chain. PSA offers many design possibilities, but to optimise the performance of a PSA system over a wide range of design choices, by experimental means, is typically too costly, in terms of time and resources required. To address this challenge, computer experiments are used to emulate the real system and to predict the performance. The system of PDAEs that describes the PSA process behaviour is however typically computationally expensive to simulate, especially as the cyclic steady state condition has to be met. Over the past decade, significant progress has been made in computational strategies for PSA design, but more efficient optimisation procedures are needed. One popular class of optimisation methods are the Evolutionary algorithms (EAs). EAs are however less efficient for computationally expensive models. The use of surrogate models in optimisation is an exciting research direction that allows the strengths of EAs to be used for expensive models. A surrogate based optimisation (SBO) procedure is here developed for the design of PSA systems. The procedure is applicable for constrained and multi-objective optimisation. This SBO procedure relies on Kriging, a popular surrogate model, and is used with EAs. The main application of this work is the design of PSA systems for CO2 capture. A 2- bed/6-step PSA system for CO2 separation is used as an example. The cycle configuration used is sufficiently complex to provide a challenging, multi-criteria example.
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Vergara, Gallego Maria Isabel. "Smarter Radios for Energy efficiency in Wireless Sensor Networks." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENM020/document.
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Les contraintes présentes dans les réseaux de capteurs impliquent l'introduction de techniques d'optimisation à différents niveaux de conception : du matériel au logiciel et dans la pile de communication. En effet, le déploiement des réseaux de capteurs, à faible consommation énergétique, exige une conception conjointe du matériel et du logiciel adaptée à l'application visée. Étant donné la nature évènementielle et multitâche des applications dans les réseaux de capteurs, nous pourrions penser à rajouter différentes unités de traitement qui coopèrent pour gérer les évènements et les tâches de manière optimale. Ainsi, la complexité des tâches accomplies par le processeur principal peut être réduite, ce qui contribue à atteindre l'efficacité énergétique. Dans cette thèse nous étudions un ensemble de protocoles qui facilitent l'implémentation des smart radios. L'idée principale des smart radios est l'introduction de l'intelligence dans la puce radio de manière à ce qu'elle soit capable de prendre des décisions ainsi que d'exécuter plusieurs tâches de manière autonome et sans l'intervention du processeur principal. Cette dernière sera responsable du bootstrap du réseau et, après qu'un état stable est atteint, le processeur peut rester inactif la plupart du temps, alors que la puce radio continue à fournir un ensemble de services. Le protocole proposé est appelé Wake on Idle et il fournit la maintenance de voisinage intégrée avec une méthode d'accès au canal. Ces services sont basés sur des transmissions analogiques qui sont codées dans le temps. De cette manière, dès que le réseau entre dans l'état stable (c.à.d. la topologie est formée et les noeuds sont associés et synchronisés), le traitement numérique de trames n'est pas nécessaire. Puisque Wake on Idle est basé sur des informations de bas niveau, il peut être facilement intégré dans la puce radio et fonctionner comme un coprocesseur qui fournit des services de haut niveau au processeur principal, comme la maintenance du voisinage et l'accès au canal. Grâce à une analyse théorique et une implémentation préliminaire, nous démontrons la faisabilité du protocole et nous montrons plusieurs caractéristiques intéressantes qui aident à atteindre l'efficacité énergétique et de bonnes performances. Ensuite, nous exploitons la signalisation analogique afin d'optimiser le duty-cycle des protocoles d'accès au canal existants. Nous proposons également un mécanisme appelé Sleep on Idle qui est basé sur l'échange de signaux analogiques ou busy tones. Sleep on Idle peut être intégré dans la radio et il peut décider quand le processeur doit être réveillé. Enfin, nous avons intégré le mécanisme de notification dans le standard IEEE802.15.4 et nous avons évalué ce mécanisme par des simulations et expérimentations. Les résultats montrent un gain important en termes de consommation en énergie et de réactivité du réseauThe constraints of Wireless Sensor Networks scenarios require the introduction of optimization techniques at different design levels: from the hardware to the software and communication protocol stack. In fact, the design of energy efficient WSNs involves an appropriate hardware/software co-design oriented to the concerned application. Given the event driven and multitasking nature of WSNs applications, one could think of adding different processing units that cooperate to manage events and tasks in an optimal way. Then, the complexity of tasks performed by the main processing unit can be reduced and energy efficiency can be achieved. In this PhD thesis we study protocols that leverage the implementation of smart radios. The idea of smart radios is introducing intelligence into the radio chip; in this way, it will be able to take decisions and perform several tasks in an autonomous way and without any intervention of the main processing unit. The processing unit will be in charge of bootstrapping the network and, after a stable state is reached, it can remain inactive most of the time while the radio chip provides a given set of services. The proposed protocol is called Wake on Idle and it provides integrated neighborhood maintenance and low duty-cycle medium access control. These services are provided based on analog transmissions that are time encoded; then, as soon as the network enters the stable state (i.e. the topology is formed and nodes are associated and synchronized) digital processing of frames is not needed. Since it relies on low-level information, Wake on Idle can be easily implemented on hardware and integrated into the radio chip; then, it works as a coprocessor that provides high-level services (i.e. neighborhood maintenance and medium access) to the main processing unit. Through theoretical analysis and a preliminary implementation we demonstrate the feasibility of the protocol and we show several interesting characteristics that help achieving energy efficiency and good performance. Then, we further exploit analog signaling to optimize duty cycle of existing medium access control protocols. We propose a mechanism called Sleep on Idle and it is based on the exchange of analog busy tones. Sleep on Idle can also be integrated into the smart radio to take decisions about whether the main processing unit has to be woken up. We apply the decision mechanism to the slotted ieee802.15.4 standard and validate it through simulations and experimentations. The results show an important gain in terms of energy consumption and network reactivity
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Amdouni, Ichrak. "Wireless Self-adaptive Ad hoc and Sensor Networks : Energy Efficiency and Spatial Reuse." Paris 6, 2013. http://www.theses.fr/2013PA066003.
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La nécessité de maximiser la durée de vie du réseau sans fil dans les réseaux ad hoc et en particulier dans les réseaux de capteurs sans fil nécessite l'utilisation d'algorithmes d'efficacité énergétique. Motivée par le fait qu'un noeud consomme le moins d'énergie lorsqu’il est en veille, nous réalisons l'efficacité énergétique vi des algorithmes d'ordonnancement des activités des noeuds. Les noeuds reçoivent des slots temporels durant lesquels ils peuvent transmettre et ils peuvent éteindre leur radio quand ils ne sont ni en train de transmettre, ni en train de recevoir. Par rapport au TDMA classique, l’utilisation de la bande passante est optimisée: deux noeuds interférents ne partagent pas les mêmes slots. Dans notre travail sur l’ordonnancement, deux cas sont étudiés. Tout d'abord, lorsque les nœuds nécessitent le même temps d’accès au canal, nous utilisons le coloriage des nœuds. Deuxièmement, lorsque les nœuds requièrent des débits hétérogènes, nous utilisons une allocation de slots « traffic aware ». Contrairement à la majorité des travaux antérieurs, nous généralisons la définition du coloriage des noeuds et les problèmes d'attribution des slots. En effet, nous considérons que la distance maximale entre deux nœuds interférents est un paramètre de ces problèmes. Nous prouvons qu'ils sont NP-complets, ce qui rend inévitable l’utilisation des heuristiques dans la pratique. Une directive centrale de cette thèse est de concevoir des solutions auto-adaptatives. Cette adaptabilité concerne de nombreux aspects tels que la mission confiée par l'application, l'hétérogénéité des demandes de trafic de nœuds, la densité du réseau, de la régularité de la topologie du réseau, et la non fiabilité des liens sans filThe need to maximize network lifetime in wireless ad hoc networks and especially in wireless sensor networks requires the use of energy efficient algorithms and protocols. Motivated by the fact that a node consumes the least energy when its radio is in sleep state, we achieveenergy efficiency by scheduling nodes activity. Nodes are assigned time slots during which they can transmit and they can turn off their radio when they are neither transmitting nor receiving. Compared to classical TDMA-based medium access scheme, spatial bandwidth use is optimized: non interfering nodes are able to share the same time slots, collisions are avoided and overhearing and interferences are reduced. In our work about time slots assignment, two cases are studied. First, when nodes require equal channel access, we use node coloring. Second, when nodes have heterogeneous traffic demands, we designed the traffic aware time slot assignment algorithm TRASA. Unlike the majority of previous works, we generalize the definition of node coloring and slot allocation problems. Indeed, we set the maximum distance between two interfering nodes as a parameter of these problems. We prove that they are NP-complete, making heuristic approaches inevitable in practice. A central directive of this thesis is to design self-adaptive solutions. This adaptivity concerns many aspects such as the mission given by the application, the heterogeneity of nnode traffic demands, the network density, the regularity of network topology, and the failure of wirelesslinks
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Falaguasta, Maria Carolina Ribeiro. "Estudo do desempenho de um precipitador eletrostático operando na captura de partículas submicrométricas e nanométricas." Universidade Federal de São Carlos, 2005. https://repositorio.ufscar.br/handle/ufscar/3969.
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Previous issue date: 2005-05-24Universidade Federal de Minas Gerais
The removal of submicron particles from gaseous streams is becoming an increasingly important operation, both in industrial (nanotechnology) as well as in occupational (inhalation of particula te matter) applications. Among the equipments commonly employed for the removal of particula tes of the gaseous stream, the electrostatic precipitator, ESP, is the one capable of removing particles of such size with high efficiency. Furthermore, it has other advantages as the low pressure drop and the flexibility of working at higher temperatures. Therefore, the objective of this research was to evaluate the influence of operational and design parameters in the efficiency of particle removal of a plate-wire ESP operating in the removal of submicron particles. The precipitator was built in acrylic, with copper plates as collecting electrodes and stainless steel wires as discharge electrodes. The study was divided in two stages: the first studied the collection of PM2.5 (high risk particle matter), using alumina, with median diameter of 0.6 mm and maximum diameter of 2.5 mm as test powder, while the stage 2 focused the nanometric range, utilizing particles of sodium chloride, with diameters between 8 and 100 nm. In stage 1, the project parameters analyzed were duct length (L), diameter of the discharge electrodes (2r) and spacing between them (2c); the operational variables were the electric field (E) and the air velocity (v). Each variable was evaluated in two levels, whose values were Lne = 15 and 30 cm; 2r = 0.045 and 0.025 cm; 2c = 4 and 2 cm; E = 5 and 8 kV/cm and, finally, v = 0.5 and 1.0 m/s. The process performance was evaluated through the analysis of the global efficiency of removal of the particula te matter, obtained through isokinetic sampling. In stage 2, the project parameter analyzed were the duct length (Lne), the ratio s/2c and the distance between the collection plates (2s) and the operational variables were the air velocity (v) and current density (j). Each operation variable was evaluated in three levels, whose values were v = 0.125, 0.25 and 0.50 m/s and j = 1.8, 2.8 and 3.8 mA/m2. The project parameters were studied in two leve ls, Lne = 15 and 30 cm and 2s = 0.04 and 0.06 m. The process performance was evaluated through the analysis of the removal efficiency of the particulates obtained by particle counting, with the use of the Condensation Particle Counter 3007, from TSI. It was observed that the precipitator possesses high collection efficiency, even in the nanometric size range, were efficiencies larger than 99% were obtained, depending on the used configuration. As expected, the increase in air velocity, as well as the decrease of the collecting plate length and of the generated current caused a decrease in the efficiency. Conversely, larger spacing between plates resulted in an increment in the efficiency, phenomenon also observed by some other researchers for larger particles. The ratio s/2c did not show a clear tendency in particle removal. When compared to models from the literature, the one that offered the better adjustment to the experimental data was the classic Deutsch model when used with a drag coefficient given by a modified version of the Li and Wang (2003a e b) equation.
A remoção de partículas submicrométricas de correntes gasosas tem-se constituído numa operação cada vez mais importante, tanto em aplicações industriais (nanotecnologia) quanto ocupacionais (inalação de material particulado). Dentre os equipamentos comumente empregados para a remoção de material particulado da corrente gasosa, o precipitador eletrostático é o que se apresenta mais apto a remover partículas de tal tamanho com alta eficiência. Desse modo, o objetivo desta pesquisa foi avaliar a influência dos parâmetros de operação e de projeto na eficiência de remoção de um precipitador eletrostático do tipo placa-fio, operando na remoção de partículas sub e nanométricas. O precipitador foi construído em acrílico e possui placas coletoras de cobre e eletrodos de descarga de aço inox. O estudo foi dividido em duas etapas: a primeira estudou a coleta de PM2,5 (material inalável de alto risco), utilizando alumina, com diâmetro mediano de 0,6 mm e diâmetro máximo de 2,5 mm, enquanto a etapa 2 focou a faixa nanométrica, utilizando partículas de cloreto de sódio, com diâmetros entre 8 e 100 nm. Na etapa 1, os parâmetros de projeto analisados foram comprimento do duto (Lne), diâmetro dos eletrodos de descarga (2r) e espaçamento entre os mesmos (2c) e as variáveis de operação foram o campo elétrico (E) e a velocidade de escoamento do ar (v). Cada variável foi avaliada em dois níveis, cujos valores foram Lne = 15 e 30 cm; 2r = 0,045 e 0,025 cm; 2c = 4 e 2 cm; E = 5 e 8 kV/cm e, finalmente, v = 0,5 e 1,0 m/s. O desempenho do processo foi avaliado através da análise da eficiência global de remoção do material particulado, obtida através de amostragem isocinética. Na etapa 2, os parâmetros de projeto analisados foram L, relação s/2c e distância entre as placas de coleta (2s) e as variáveis de operação foram v e densidade de corrente (j). Cada variável de operação foi avaliada em três níveis, cujos valores são v = 0,125, 0,25 e 0,50 m/s e jne = 1,8, 2,8 e 3,8 mA/m2. Já os parâmetros de projeto foram estudados em dois níveis, Lne = 15 e 30 cm e 2s = 0,04 e 0,06 m. O desempenho do processo foi avaliado através da análise da eficiência de remoção do material particulado, obtida através da contagem de partículas. Observou-se que o precipitador possui grande capacidade de coletar partículas até mesmo na faixa nanométrica, obtendo eficiências para alguns casos maiores que 99%, dependendo da configuração utilizada. Como esperado, o aumento da velocidade do gás, bem como a diminuição do comprimento das placas coletoras e da corrente gerada, causaram uma diminuição da eficiência. Em contrapartida, o maior espaçamento entre as placas acarretou um incremento na eficiência, fenômeno também observado por alguns outros pesquisadores para partículas maiores. A relação s/2c não apresentou uma tendência clara na remoção do material particulado. Quando avaliados os modelos presentes na literatura, aquele que melhor se ajustou aos dados experimentais foi o modelo clássico de Deutsch, quando utilizado o coeficiente de arraste dado por uma versão modificada da equação de Li e Wang (2003a e b).
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Watteyne, Thomas. "Energy-Efficient Self-Organization for Wireless Sensor Networks." Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0082/these.pdf.
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In a wireless sensor network, multi-hop communication between sensors. Major challenges include energy-efficiency (sensors are powered by on-board batteries) and self-organization (continuously adapting to topological changes). The contributions of the thesis work are: - We propose a medium access control protocol which avoids maintaining neighbourhood tables at each sensor This protocol only builds this table on demand, which provides robustness against topological changes. - We use virtual coordinates as a basis for self-organizing a wireless sensor network. Each sensor contains virtual coordinates which a routing protocol uses to find a multi-hop path to the sink, locally. By continuously updating these virtual coordinates, the proposed technique is sink, locally. By continuously updating these virtual coordinates, the proposed technique is robust against changes in the environment. We combine proposed protocols to form a cross-layered communication architecture. Experimental studies show the energy-efficiency and robustness of our proposalsDans un réseau de capteurs, les nœuds communiquent en mode multi-sauts. Les principaux enjeux de ces réseaux sont d’économiser l’énergie (ressource limitée car embarquée dans le capteur) et l’auto-organisation (afin de s’adapter aux changements de topologie). Les contributions majeures de cette thèse sont: - Nous proposons un protocole d’accès au médium qui évite le maintien des tables de voisinage pour chaque nœud. Notre protocole ne construit cette table qu’à la demande, ce qui permet d’être robuste aux changements de topologies. - Nous utilisons des coordonnées virtuelles comme base pour l’auto-organisation du réseau de capteurs. Ces coordonnées sont utilisées par un protocole de routage pour découvrir des chemins multi-sauts. Chaque capteur met continuellement à jour ses coordonnées pour augmenter la robustesse. - Nous combinons ces propositions pour former une architecture de communication transcouches. Des résultats expérimentaux montrent l’efficacité de nos propositions
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Soua, Ridha. "Wireless sensor networks in industrial environment : energy efficiency, delay and scalability." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2014. http://tel.archives-ouvertes.fr/tel-00978887.
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Some industrial applications require deterministic and bounded gathering delays. We focus on the joint time slots and channel assignment that minimizes the time of data collection and provides conflict-free schedules. This assignment allows nodes to sleep in any slot where they are not involved in transmissions. Hence, these schedules save the energy budjet of sensors. We calculate the minimum number of time slots needed to complete raw data convergecast for a sink equipped with multiple radio interfaces and heterogeneous nodes traffic. We also give optimal schedules that achieve the optimal bounds. We then propose MODESA, a centralized joint slots and channels assignment algorithm. We prove the optimality of MODESA in specific topologies. Through simulations, we show that MODESA is better than TMCP, a centralized subtree based scheduling algorithm. We improve MODESA with different strategies for channels allocation. In addition, we show that the use of a multi-path routing reduces the time of data collection .Nevertheless, the joint time slot and channels assignment must be able to adapt to changing traffic demands of the nodes ( alarms, additional requests for temporary traffic ) . We propose AMSA , an adaptive joint time slots and channel assignment based on incremental technical solution. To address the issue of scalability, we propose, WAVE, a distributed scheduling algorithm for convergecat that operates in centralized or distributed mode. We show the equivalence of schedules provided by the two modes.
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Nguyen, Viet-Hoa. "Energy-efficient cooperative techniques for wireless body area sensor networks." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S011/document.
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Pour réduire la consommation d'énergie due aux transmissions radio dans les réseaux de capteurs sans fil, nous proposons une nouvelle approche associant les techniques de précodage MIMO et de relais, appelé précodage distribué max-dmin (DMP). Considérant une source et un relais avec une antenne chacun, et une destination disposant de deux antennes, nous déployons un système MIMO précodé virtuel 2 × 2. Dans ce contexte, nous étudions deux techniques de relais Amplify and Forward (AF) et Decode and Forward (DF). Des comparaisons en termes de taux d'erreur et d'efficacité énergétique par rapport aux systèmes plus classiques comme les codes spatio-temporels distribués ou les combinaisons à gain maximal montrent que notre système est intéressant pour des distances de transmission moyennes (à partir de 16 mètres). Toujours dans l'objectif de maximiser l'efficacité énergétique, nous proposons une allocation de puissance sur les nœuds source et relais. Pour cela, nous dérivons analytiquement les performances du système précodage distribué max-dmin selon le mode AF et DF. Enfin,pour améliorer les performances des systèmes avec décodage au relais (DF), nous proposons un nouveau récepteur (à la destination) qui tient compte des erreurs éventuelles au niveau du relaisAmong various cooperative techniques aiming to reduce power consumption for transmissions between Wireless Body Area Networks (WBAN) and base stations, we present a new approach, named distributed max-dmin precoding (DMP), combining MIMO precoding techniques and relay communications. This protocol is based on the deployment of a virtual 2 × 2 max-dmin precoding over one source, one forwarding relay, both equipped with one antenna and a destination involving 2 antennas. In this context, two kinds of relaying, amplify and forward (AF) or decode and forward (DF) protocols, are investigated. The performance evaluation in terms of Bit-Error-Rate (BER) and energy efficiency are compared with non cooperative techniques and the distributed space time block code (STBC) scheme. Our investigations show that the DMP takes the advantage in terms of energy efficiency from medium transmission distances (after 10 meters). In order to maximise the energy efficiency, we propose a power allocation over the source and the relay. Thus, we derive the performance of our system, both for AF and DF, analytically. To further increase the performance of DF cooperative schemes, we also propose to design a new decoder at the destination that takes profit from side information, namely potential errors at the relay
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Ben, Messaoud Rim. "Towards efficient mobile crowdsensing assignment and uploading schemes." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1031/document.
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L’ubiquité des terminaux intelligents équipés de capteurs a donné naissance à un nouveau paradigme de collecte participative des données appelé Crowdsensing. Pour mener à bien les tâches de collecte, divers défis relatifs à l’implication des participants et des demandeurs de services doivent être relevés. Dans ce contexte, nous abordons quatre questions majeures inhérentes à ce problème: Comment affecter les tâches de collecte afin de maximiser la qualité des données d’une façon éco-énergétique ? Comment minimiser le temps nécessaire à la collecte et au traitement des tâches? Comment inciter les participants à dédier une partie de leurs ressources pour la collecte? et Comment protéger la vie privée des participants tout en préservant la qualité des données reportées ? Tout d’abord, nous nous intéressons au fait que les ressources énergétiques des terminaux mobiles restent limitées. Nous introduisons alors des modèles de déploiement de tâches qui visent à maximiser la qualité des données reportées tout en minimisant le coût énergétique global de la collecte. Ainsi, notre première contribution se matérialise en un modèle d’allocation appelé, QEMSS. QEMSS définit des métriques de qualité de données et cherche à les maximiser en se basant sur des heuristiques utilisant la recherche taboue. De plus, afin de rendre le processus d’allocation résultante plus équitable, nous faisons appel à un deuxième algorithme, F-QEMSS, extension de QEMSS. Les deux solutions ont permis d’obtenir des niveaux de qualité de données compétitifs principalement dans les situations défavorables des zones de faible densité ou de ressources limitées. En outre, afin de minimiser le temps moyen de collecte et de traitement des données, une deuxième phase d’allocation distribuée est ajoutée. Plus précisément, nous proposons dans cette deuxième contribution de désigner des participants responsables de déléguer des tâches. Ces derniers prédisent le comportement d’autres utilisateurs en termes de mobilité et de préférences de collecte. Par conséquent, nous développons deux types d’allocation; MATA qui ne tient compte que de la mobilité et P-MATA qui tient compte à la fois de la mobilité et des préférences des participants. Les deux allocations démontrent que l’estimation des préférences des utilisateurs minimise le temps de collecte et évite le rejet des tâches. La troisième contribution de cette thèse, IP-MATA+, propose des incitations aux participants, ce qui favorise leur engagement aux campagnes de collecte notamment quand le budget dédié est partagé en fonction de la qualité des contributions. Pour finir, nous considérons la problématique de la vie privée des participants au crowdsensing. Particulièrement, nous ciblons la minimisation du risque de divulgation de la vie privée durant la phase du déchargement tout en veillant à l’utilité des données collectées. Ainsi, la quatrième contribution de cette thèse vise à assurer simultanément deux objectifs concurrents, à savoir assurer l’utilité des données nécessaire aux demandeurs et protéger les informations sensibles des participants. Pour ce faire, nous introduisons une entité de confiance dans le système de collecte ayant pour rôle d’exécuter un mécanisme qui génère une version altérée de la donnée collectée qui répond au compromis de protection et d’utilité. La solution développée, appelée PRUM, a été évaluée sur des datasets de collecte participative en variant les scénarios d’attaque et de déchargement des données. Les résultats obtenus prouvent qu’une altération limitée des données collectées peut assurer une protection des informations sensibles des participants tout en préservant environ 98% de l’utilité des données obtenue pour les demandeurs. Pour conclure, nos contributions abordent diverses problématiques complémentaires inhérentes à la collecte participative des données ouvrant la voie à des mises en œuvre réelles et facilitant leur déploiementThe ubiquity of sensors-equipped mobile devices has enabled people to contribute data via crowdsensing systems. This emergent paradigm comes with various applications. However, new challenges arise given users involvement in data collection process. In this context, we introduce collaborative sensing schemes which tackle four main questions: How to assign sensing tasks to maximize data quality with energy-awareness? How to minimize the processing time of sensing tasks? How to motivate users to dedicate part of their resources to the crowdsensing process ? and How to protect participants privacy and not impact data utility when reporting collected sensory data ? First, we focus on the fact that smart devices are energy-constrained and develop task assignment methods that aim to maximize sensor data quality while minimizing the overall energy consumption of the data harvesting process. The resulting contribution materialized as a Quality and Energy-aware Mobile Sensing Scheme (QEMSS) defines first data quality metrics then models and solves the corresponding optimization problem using a Tabu-Search based heuristic. Moreover, we assess the fairness of the resulted scheduling by introducing F-QEMSS variant. Through extensive simulations, we show that both solutions have achieved competitive data quality levels when compared to concurrent methods especially in situations where the process is facing low dense sensing areas and resources shortcomings. As a second contribution, we propose to distribute the assignment process among participants to minimize the average sensing time and processing overload com- pared to a fully centralized approach. Thus, we suggest to designate some participants to carry extra sensing tasks and delegate them to appropriate neighbors. The new assign- ment is based on predicting users local mobility and sensing preferences. Accordingly, we develop two new greedy-based assignment schemes, one only Mobility-aware (MATA) and the other one accounting for both preferences and mobility (P-MATA), and evaluate their performances. Both MATA and P-MATA consider a voluntary sensing process and show that accounting for users preferences minimize the sensing time. Having showing that, our third contribution in this thesis is conceived as an Incentives-based variant, IP-MATA+. IP-MATA+ incorporates rewards in the users choice model and proves their positive impact on enhancing their commitment especially when the dedicated budget is shared function of contributed data quality. Finally, our fourth and last contribution addresses the seizing of users privacy concerns within crowdsensing systems. More specifically, we study the minimization of the incurred privacy leakage in data uploading phase while accounting for the possible quality regression. That is, we assess simultaneously the two competing goals of ensuring queriers required data utility and protecting participants’ sensitive information. Thus, we introduce a trust entity to the crowdsensing traditional system. This entity runs a general privacy-preserving mechanism to release a distorted version of sensed data that responds to a privacy-utility trade-off. The proposed mechanism, called PRUM, is evaluated on three sensing datasets, different adversary models and two main data uploading scenarios. Results show that a limited distortion on collected data may ensure privacy while maintaining about 98% of the required utility level.The four contributions of this thesis tackle competing issues in crowdsensing which paves the way at facilitating its real implementation and aims at broader deployment