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Hopker, James G. "An Investigation of efficiency within Cycling." Thesis, University of Kent, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504668.
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Zamparo, Paola. "Optimization and transmission efficiency in human locomotion." Thesis, Manchester Metropolitan University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251301.
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Harper, Sara Anne. "The influence of lateral foot displacement on cycling efficiency and maximal cycling power." Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1394551229.
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Saunders, S. C. "The effect of body mass change on cycling efficiency." Thesis, Canterbury Christ Church University, 2016. http://create.canterbury.ac.uk/15091/.
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Cycling efficiency is a measure of the ability to convert stored energy into power, and is considered a key determinant of cycling performance. Cycling efficiency has recently been manipulated with various techniques, but most prominently with high intensity training in habitual cyclists and using calorie restriction in sedentary obese participants. It was therefore the primary aim of this thesis to explore the efficacy of utilising a short- and medium-term calorie restriction intervention, to manipulate efficiency with participants accustomed to cycling. A secondary aim was to investigate the validity of measuring efficiency in a field-based environment. Male club level cyclists were recruited for the investigations, which comprised of a moderate -500 kcal.day-1 deficit, utilising portion control and measuring efficiency at both absolute and relative steady-state intensities. Seventeen participants completed the short-term, two-week intervention which utilised a randomised cross-over design. Although a significant reduction in body mass was attained, RMR, gross and net efficiency across all intensities and TT power remained stable. Field and laboratory comparisons indicated that prior to statistical correction absolute efficiency was significantly lower in the field, but after accounting for differences in power, cadence and environmental conditions, no differences were present. Twenty-nine participants conducted the medium-term study and were assigned either to calorie restriction or to no dietary intervention. Following a reduction in mass in the calorie restriction group and an increase in the group given no dietary intervention, a significant interaction between mass and efficiency was found across gross and net efficiency workloads. A six week follow-up period indicated that the process of calorie restriction and not absolute body mass reduction was the main mechanism for altering efficiency. This thesis suggests that efficiency can be manipulated both positively and negatively with calorie manipulation, and that these changes are linked to both laboratory and field based performance.
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Wainright, Jesse Sumner. "Polypyrrole deposition and cycling efficiency: Rutherford backscattering spectroscopy studies." Case Western Reserve University School of Graduate Studies / OhioLINK, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=case1056463837.
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Passfield, Louis. "Gross efficiency, maximal muscle function and cycling endurance exercise." Thesis, University of Brighton, 1998. https://research.brighton.ac.uk/en/studentTheses/3148c501-f2df-4049-8a98-3a05b56af2ca.
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Prolonged moderate intensity cycle exercise is associated with a gradual and progressive reduction in gross efficiency (GE). It was speculated that this loss of GE might reflect a reduction in maximal muscle function and result in a parallel decline in aerobic performance. The effect of prolonged moderate intensity cycle exercise on maximal muscle function and anaerobic performance has not been clearly established. This thesis examined the impact of 1-2 h of cycling exercise at 60-65% maximal aerobic power in well-trained cyclists on subsequent changes in aerobic and anaerobic performance, GE and maximal muscle function.
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Li, Jing. "Duty Cycling for Energy Efficiency in Wireless Sensor Networks and Applications." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1349110340.
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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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Leib, Daniel J. "The effects of cleat placement of muscle mechanics and metabolic efficiency in prolonged sub-maximal cycling." CardinalScholar 1.0, 2008. http://liblink.bsu.edu/uhtbin/catkey/1427389.
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This study quantified the changes in pedaling mechanics and energy expenditure accompanying a posterior shift in cleat placement during prolonged cycling. Six male competitive cyclists participated. Each subject was asked to complete two separate hour long rides using traditional cleat placement and a novel heel placement, respectively. Expired gasses, kinematics, and EMG from 7 lower limb muscles were collected at three time intervals during each ride. No significant difference in O2 utilization was seen (p=0.905). A significant difference was seen in sagittal plane knee angle (p=0.008) and angular velocity (p=0.003) in the heel condition, demonstrating a more extended knee and lower peaks in angular velocity. Musculo-tendon kinematic data showed no differences. Tibialis anterior (TA) iEMG was higher in the heel condition, and SOL and TA showed differences in timing between conditions. These results demonstrate changes in ankling patterns and knee joint kinematics as adaptations to heel pedaling.School of Physical Education, Sport, and Exercise Science
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O'Hara, Christiane Rose. "Effects of chainring design on performance in competitive cyclists." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/625.
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The development of noncircular chainrings to improve cycling performance has been in progress since the 1980’s and continues apace. The aim of this study was to compare performance time and physiological responses in cycling using a standard circular chainring versus a noncircular chainring developed in 2005: the Rotor Q-Ring. Eight competitive male cyclists were pre-tested using the original circular chainrings and also on the initial week of testing. The intervention consisted of cycling with Rotor Q-Rings for four weeks. Post-testing occurred with the original chainrings for the final week of testing. Testing consisted of a maximal or submaximal graded exercise test followed by a 1 k time trial. Oxygen consumption, carbon dioxide output, heart rate, ventilation, respiratory exchange ratio, and perceived exertion were continuously measured during the tests. Blood lactate concentration was measured during the last 30 s of each three minute stage. Five minutes after the submaximal test, participants performed an “all out” 1 k trial for time as well as maximum and average power. The main findings were: 1) Participants were on average 1.6 seconds faster in the 1 k time trial with Rotor Q-Rings compared to a circular chainrings. 2) There was a significant increase in average power (26.7 watts) and average speed (0.7 kph) during the 1 k time trial with Rotor Q-Rings. 3) Oxygen consumption (during weeks 2-4) and heart rate (weeks 1-3) were significantly lower with Rotor Q-Rings during submaximal testing when compared to circular chainrings. However, in contrast to our hypotheses no benefits were observed for other submaximal dependent measures (i.e., CO2, VE, RER, RPE, GE, DE, and lactate).
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Devlin, Tate Bross. "The Influence of Body Composition on Cadence Efficiency in Competitive Cyclists." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470146734.
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Burns, Jack. "Does training with PowerCranks affect economy of motion, cycling efficiency, oxygen uptake and muscle activation patterns in trained cyclists?" Connect to thesis, 2008. http://adt.ecu.edu.au/adt-public/adt-ECU2008.0017.html.
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Scheps, Amanda. "An evaluation of cardiorespiratory responses and ventilatory efficiency during treadmill and cycling exercise in overweight adolescents." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2313.
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The assessment of ventilatory efficiency (VE/VCO2 slope) is increasingly being utilized to complement traditional cardiorespiratory fitness testing during graded exercise. The purpose of this study was to compare cardiorespiratory responses and ventilatory efficiency in obese children during a progressive exercise test to volitional fatigue performed on a treadmill and a cycle ergometer. Fifteen obese male (N=3) and female (N=12) adolescents aged 10 to 18 years were recruited in the study and completed both the treadmill and cycle ergometer trials. Mean age and BMI of the sample was 13.3 years and 38.0 kg/m2, respectively. Maximal oxygen consumption (VO2max) and ventilatory efficiency were determined during both exercise trials. Subsequently, overall VE/VCO2 slope and the slope below and above AT for ventilatory efficiency were compared between the two exercise modes. VO2max was significantly (p<0.05) greater during the treadmill trial (26.09±5.11 ml/kg/min) compared to the cycle ergometer trial (20.71± 4.31 ml/kg/min). The VO2 at anaerobic threshold (AT) was significantly (p<0.05) higher during the treadmill trial, however, the percentage of VO2max at AT was not significantly different between the two modes (treadmill-63.41± 6.29% and cycle ergometer (67.25± 6.99%). While there was no significant difference in the overall VE/VCO2 slope or the VE/VCO2 slope above anaerobic threshold obtained from the two modes, the VE/VCO2 slope below anaerobic threshold was significantly (p<0.05) higher in the treadmill trial (25.06±2.10) compared to the cycle ergometer trial (23.34± 2.12). In our small sample of obese adolescents, we observed a greater VE response for a given VCO2 during treadmill exercise below the anaerobic threshold. The differences observed may be related to a greater activation of muscle afferents during weight bearing exercise in obese adolescents.
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Safi, Zikrullah [Verfasser]. "Nutrient cycling and nutrient use efficiency in urban and peri-urban agriculture of Kabul, Afghanistan / Zikrullah Safi." Kassel : Universitätsbibliothek Kassel, 2011. http://d-nb.info/1012867978/34.
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Andersson, Rasmus, and Viktor Wahrenberg. "Sambandet mellan delta efficiency i cykling och löpning för elitaktiva triathleter." Thesis, Högskolan Dalarna, Idrotts- och hälsovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:du-36489.
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SyfteSyftet med denna studie var att undersöka sambandet mellan delta efficiency (DE) i cykling (DEcykel) och löpning (DElöp) för elitaktiva triathleter. Vidare syftade studien till att undersöka om DEcykel och DElöp skiljer sig samt om det är skillnad i DE mellan kvinnliga och manliga triathleter vid respektive aktivitet.MetodFem kvinnliga (22 ± 6 år) och fem manliga (24 ± 5 år) elitaktiva triathleter utförde två submaximala test, ett cykeltest och ett löptest på rullband med konstant lutning på 2,5˚. Hastigheten ökad stegvis med 2,4 km·tim-1 under cykeltestet och 0,6 km·tim-1 under löptestet för respektive intervall á fem minuter för att fastställa DE. DE är förhållandet mellan förändringen i utfört arbete och förändringen i energiförbrukning, presenterat i procent. Triathleterna använde sin personliga cykel- och löputrustning.ResultatDet fanns inget statistiskt samband mellan DEcykel och DElöp för elitaktiva triathleter (p > 0,05). En statistisk signifikant skillnad påvisades mellan DEcykel och DElöp (p < 0,001). Ingen skillnad i varken DEcykel eller DElöp upptäcktes mellan kvinnor och män (båda p > 0,05).SlutsatserTriathleters DEcykel är signifikant högre än DElöp. Det upptäcktes inget samband mellan DEcykel och DElöp bland triathleterna på individnivå vilket innebär att en triathlet med högt värde för DEcykel inte per automatik även har högt värde för DElöp. Ingen könsrelaterad skillnad upptäcktes bland triathleterna.PurposeThe purpose of the present study was to investigate the relationship between delta efficiency (DE) in cycling (DEcycle) and running (DErun) among elite triathletes. Furthermore, another aim of the study was to investigate if DE differ between the activities and/or gender.MethodsFive elite female (22 ± 6 years) and five elite male (24 ± 5 year) triathletes preformed two submaximal tests, a cycling test and a running test on a motorized treadmill in a constant inclination of 2,5˚. The treadmill speed between stages was increased by 2.4 km·h-1 for the cycling test and 0.6 km·h-1 for the running test. Each stage was five minutes followed by a one minute pause. DE is the relation between the change in work rate (WR) and the change in metabolic rate (MR), presented in percentages. The triathletes own bikes and running equipment were used during the tests.ResultsThe results did not show a relationship between DEcycle and DErun between elite triathletes (p > 0,05). A statistical significant difference was found between DEcycle and DErun (p < 0,001). No gender difference was found for either DEcycle or DErun (both p > 0,05).ConclusionsThe DEcycle were significantly higher among the triathletes compared to DErun. No relationship between DEcycle and DErun were found, which means that triathletes with a grate DEcycle does not automatically have a grate DErun. No gender related difference was discovered between the triathletes.
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Aguiar, Maria Ivanilda de. "Productivity, nutrient cycling and emergy efficiency as functions of plant diversity in agricultural systems and preserved caatinga vegetation." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8884.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoNutrient cycling and energy transformation processes fuel plant productivity and are directly related to ecosystem diversity. The preservation of diversity has thus been identified as a way to improve the sustainability of agroecosystems. It also follows that agroforestry systems (AFS) are recommended since they maintain high plant diversity, increase carbon and nutrient stocks and promote emergy efficiency. Agroforestry systems represent an alternative to traditional agricultural systems, which are responsible for large losses of diversity and environmental degradation in Brazilâs semiarid northeast. It is assumed that the greater plant diversity in AFS yields greater productivity, improves soil nutrient inputs, and increases carbon and nutrient stocks as well as energy efficiency. We evaluated a model agroforestry production system consisting of three areas: agrosilvopastoral, silvopastoral and preserved caatinga vegetation (CAT). Also, data was taken from a traditional management system including an area under cropping and two areas under fallow for six and nine years. The objectives of this work were to assess whether AFS remain similar to preserved vegetation and whether fallow periods restore land to its initial condition, in terms of: (i) the species composition and community structure of herbaceous and tree/shrub strata; (ii) plant diversity and biomass production; (iii) carbon and nutrient stocks in standing vegetation, litter and the soil and (iv) emergy flux transformations. We found that species composition and plant productivity were similar in the AFS and preserved caatinga, however in AFS the structure of the plant community was modified and diversity indices were reduced. Soil carbon and nutrient stocks in AFS were similar to those in CAT, but stocks in standing biomass and litter were lower. Overall, the AFS performed better in terms of emergy, due to more efficient energy use, a lesser environmental impact and greater renewability. The fallow periods following traditional cropping allowed the species composition, productivity and carbon and nutrient stocks in soil and litter to recover. However, areas under fallow differed from CAT in terms of tree community structure, with a greater number of individuals and species. Tree species found in fallow areas reach smaller sizes than under CAT. Therefore total biomass and carbon and nutrient stocks were lesser under fallow than CAT. Agroforestry systems managed in an integrated fashion represent great potential for sustainability, since they provide agricultural, pastoral and wood products while maintaining vegetation structure characteristics which allow constant fluxes of energy and nutrient cycling, as occurs under preserved vegetation.
Os processos de ciclagem de nutrientes e transformaÃÃes energÃticas impulsionam a produtividade e estÃo diretamente relacionados com a diversidade dos ecossistemas. Assim, tem-se priorizado a manutenÃÃo da diversidade em Ãreas agrÃcolas para a conduÃÃo de agroecossistemas mais sustentÃveis. Neste sentido, os sistemas agroflorestais (SAFs) sÃo recomendados por manter elevados nÃveis de diversidade vegetal, aumentar os estoques de carbono e nutrientes e promover eficiÃncia nas transformaÃÃes energÃticas. Os SAFs sÃo indicados para substituÃr os sistemas agrÃcolas tradicionais responsÃveis por grande perda de diversidade e degradaÃÃo ambiental na regiÃo semiÃrida nordestina. Espera-se que nos SAFs, a maior diversidade vegetal proporcione maior produtividade, maior retorno de nutrientes ao solo, maiores estoques de carbono e nutrientes e melhor eficiÃncia emergÃtica. Um modelo de produÃÃo agroflorestal composto de trÃs Ãreas foi avaliado: agrossilvipastoril (ASP), silvipastoril (SP) e caatinga conservada (CAT); e um sistema de manejo tradicional, composto de uma Ãrea em cultivo (AG), e duas Ãreas em pousio de seis (P6) e nove (P9) anos. Este trabalho objetivou verificar se os SAFs mantÃm-se semelhantes a vegetaÃÃo conservada e se os perÃodos de pousio retornam as Ãreas a sua condiÃÃo inicial, quanto a: (1) composiÃÃo florÃstica e estrutura da comunidade dos componentes herbÃceos e arbÃreo/arbustivo; (2) diversidade e produÃÃo de biomassa; (3) estoques de carbono e nutrientes presentes nas plantas, serrapilheira e solo e (4) transformaÃÃes dos fluxos emergÃticos. Verificou-se que as Ãreas sob SAFs apresentam composiÃÃo florÃstica e produtividade semelhante a caatinga conservada, porÃm este manejo provoca modificaÃÃes estruturais na comunidade vegetal e reduÃÃo nos Ãndices de diversidade. Os estoques de carbono e nutrientes nos SAFs sÃo semelhantes a CAT no compartimento solo, porÃm foram inferiores nas plantas e na serrapilheira. Contudo, o modelo agroflorestal apresenta melhor desempenho emergÃtico devido sua melhor eficiÃncia na utilizaÃÃo de energia, menor impacto ambiental e maior renovabilidade. Durante os perÃodos de pousio adotados apÃs o cultivo tradicional as Ãreas se recuperaram em relaÃÃo a composiÃÃo florÃstica, a produtividade e os estoques de carbono e nutrientes no solo e na serrapilheira. Entretanto, apresentaram modificaÃÃes quanto a estrutura da comunidade arbÃrea, com maior nÃmero de indivÃduos e espÃcies, sendo estes de menor porte e assim, menor biomassa total e menor estoques de carbono e nutrientes. Os sistemas de produÃÃo agroflorestal utilizados de forma integrada apresentam grande potencial de sustentabilidade, por proporcionarem a produÃÃo agrÃcola, pastoril e madeireira, mantendo diversas caracterÃsticas estruturais da vegetaÃÃo que permitem um fluxo de energia e uma ciclagem de nutrientes constante, assim como em Ãreas conservadas.
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BURNS, Jack, and jack burns@ecu edu au. "Does training with PowerCranks(tm) affect economy of motion, cycling efficiency, oxygen uptake and muscle activation patterns in trained cyclists?" Edith Cowan University. Computing, Health And Science: School Of Exercise, Biomedical & Health Science, 2008. http://adt.ecu.edu.au/adt-public/adt-ECU2008.0017.html.
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PowerCranks(tm) are claimed to increase economy of motion and cycling efficiency by reducing the muscular recruitment patterns that contribute to the resistive forces occurring during the recovery phase of the pedal stroke. However, scientific research examining the efficacy of training with PowerCranks(tm) is lacking. Therefore, the purpose of this study was to determine if five weeks of training with PowerCranks(tm) improves economy of motion (EOM), gross efficiency (GE), oxygen uptake (V.O2) and muscle activation patterns in trained cyclists. Sixteen trained cyclists were matched and paired into either a PowerCranks(tm) (PC) or Normal Cranks (NC) training group. Prior to training, all subjects completed a graded exercise test (GXT) using normal bicycle cranks. Additionally, on a separate day the PC group performed a modified GXT using PowerCranks? and cycled only until the end of the 200W stage (PCT). During the GXT and PCT, FeO2, FeCO2 and V.E were measured to determine EOM, GE and V.O2max. Integrated electromyography (iEMG) was also used to examine selected muscular activation patterns. Subjects then repeated the tests following the completion of training on their assigned cranks.
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Harris, Kevin W. "The effects of the powercam crank system on physiological and perceptual indicators of efficiency in humans during endurance cycling." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/94461.
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Six adult male volunteers of similar body size (x̄ ± SD:ht = 184.6 ± 6.4 cm; wt = 80.86 ± 2.7 kg) and aerobic exercise capacity (VO₂ = 38 ± 3.1 ml·kg⁻¹. min⁻¹) were tested to determine what physiological and perceptual differences existed during endurance cycling using a Powercam (Houdaille, Inc.) crank system (CAM) as compared to a standard crank system (STD).
Following preliminary tests to determine the subject's working capacity, each was assigned to ride either in the CAM or STD mode for 1 hour using a gear ratio that would require an effort equal to 70% of the VO₂ max. After a minimum of 72 hours between trials, subjects were retested in the converse mode. Measurements that included HR, BP, VO₂, surface EMG, and RPE were monitored at 15 minute intervals during both tests.
Responses were very similar across modes and between subjects. Although subjects demonstrated responses that may indicate an improved efficiency for a particular mode, the group did not display patterns that would indicate efficiency for the Powercam crank system.M.S.
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Burns, Jack. "Does training with PowerCranks™ affect economy of motion, cycling efficiency, oxygen uptake and muscle activation patterns in trained cyclists?" Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2008. https://ro.ecu.edu.au/theses/17.
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PowerCranks™ are claimed to increase economy of motion and cycling efficiency by reducing the muscular recruitment patterns that contribute to the resistive forces occurring during the recovery phase of the pedal stroke. However, scientific research examining the efficacy of training with PowerCranks™ is lacking. Therefore, the purpose of this study was to determine if five weeks of training with PowerCranks™ improves economy of motion (EOM), gross efficiency (GE), oxygen uptake (V.O2) and muscle activation patterns in trained cyclists. Sixteen trained cyclists were matched and paired into either a PowerCranks™ (PC) or Normal Cranks (NC) training group. Prior to training, all subjects completed a graded exercise test (GXT) using normal bicycle cranks. Additionally, on a separate day the PC group performed a modified GXT using PowerCranks™ and cycled only until the end of the 200W stage (PCT). During the GXT and PCT, FeO2, FeCO2 and V.E were measured to determine EOM, GE and V.O2max. Integrated electromyography (iEMG) was also used to examine selected muscular activation patterns. Subjects then repeated the tests following the completion of training on their assigned cranks.
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Marwede, Max [Verfasser], and Armin [Akademischer Betreuer] Reller. "Cycling critical absorber materials of CdTe- and CIGS-photovoltaics: Material efficiency along the life-cycle / Max Marwede. Betreuer: Armin Reller." Augsburg : Universität Augsburg, 2013. http://d-nb.info/1077703074/34.
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Tsujii, Yuki. "Significance of the phosphorus-use strategies of trees for the cycling of phosphorus in Bornean tropical rainforest ecosystems." Kyoto University, 2018. http://hdl.handle.net/2433/232348.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第21147号
農博第2273号
新制||農||1058(附属図書館)
学位論文||H30||N5121(農学部図書室)
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 北山 兼弘, 教授 小杉 緑子, 教授 北島 薫
学位規則第4条第1項該当
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Goldstein, Renee B. "Comparison of Prototype Bicycle Pedal VS Traditional, Fixed Pedal and it's Effect on Efficiency and Power Output." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1304519913.
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Carlsson, Marie. "Sambandet mellan rörelseekonomin vid cykling och löpning för elitaktiva triathleter." Thesis, Högskolan Dalarna, Idrotts- och hälsovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:du-36493.
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SyfteSyftet med denna studie var att undersöka om det finns ett samband mellan rörelseekonomin (GE) i cykling och löpning, hos elitaktiva triathleter. Vidare syftar denna studie till att undersöka om det finns någon skillnad mellan GE vid cykling och löpning samt om det finns någon könsmässig skillnad i GE för dessa två olika aktivitetsformer.MetodStudiedeltagarna (5 kvinnor, 5 män) (23 ± 7,5 år) genomförde ett cykeltest och ett löptest för att bestämma deltagarnas GE. Rullbandets lutning var 2,5º och intensitetsnivåerna varade fem minuter med en minuts stående vila. För varje ny nivå ökade hastigheten med 2,4 km∙tim-1 vid cykeltestet och 0,6 km∙tim-1 vid löptestet. Under testen analyserades deltagarnas syreupptagning samt direkt efter avslutad nivå togs ett laktatprov. Deltagarnas GE beräknades utifrån den relativa arbetsnivån där laktathalten stigit 1 mmol∙l-1 från det lägsta uppmätta värdet. Pearsons korrelation, oberoende t-test och parat t-test genomfördes för att kunna identifiera eventuella samband, könsskillnader respektive skillnader för de två aktivitetsformerna avseende GE. Alfanivån för statistisk signifikans sattes till 0,05.ResultatDet var ett signifikant samband mellan GE för cykling och löpning (p = 0,041). Det förekom ingen könsmässig skillnad i GE för varken cykling (p = 0,59) eller löpning (p = 0,31). Däremot är GE för cykling högre än för löpning (p < 0,001).SlutsatserEn triathlet med högt GE vid cykling har generellt sett ett högt GE vid löpning, trots att dessa aktivitetsformer skiljer sig åt såväl koordinativt som utifrån ett GE-perspektiv.PurposeThe aim of this study was to investigate whether there is a correlation between gross efficiency (GE) in cycling and running among elite triathletes. Furthermore, this study aims to investigate if there is a difference between GE in cycling and running and whether there is any gender difference in GE for these two different forms of activity.MethodsThe participants (5 women, 5 men) (23 ± 7.5 years) performed a cycle test and a running test to determine the participants’ GE. The treadmill inclination was set to 2.5º and the intensity levels lasted five minutes with one minute standing rest. For each new level, the speed increased by 2.4 km∙h-1 in the cycling test and 0.6 km∙h-1 in the running test. During the tests, the participants’ oxygen uptake was analysed and a lactate sample was taken immediately after the completed level. The participants’ GE was calculated based on the relative work intensity where the lactate concentration increased 1 mmol∙l-1 from the lowest measured value. Pearson's correlation, independent samples t-test and paired sample t-test were conducted to identify relationship, gender differences, and difference in GE between the activity forms, respectively. The alpha level for statistical significance was set to 0.05.ResultsThere was a significant correlation between GE in cycling and running (p = 0.041). There was no significant gender difference in GE for either cycling (p = 0.59) or running (p = 0.31). However, GE in cycling was higher than in running (p < 0,001).ConclusionsA triathlete with high GE in cycling generally has a high GE in running, despite that these forms of activity differ both coordinatively and from a GE perspective.
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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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Sciullo, Luca. "Energy-efficient wireless sensor networks via scheduling algorithm and radio Wake-up technology." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14539/.
Full textAbstract:
One of the most important requirements for wireless sensor networks (WSNs) is the
energy efficiency, since sensors are usually fed by a battery that cannot be replaced
or recharged. Radio wake-up - the technology that lets a sensor completely turn
off and be reactivated by converting the electromagnetic field of radio waves into
energy - is now one of the most emergent strategies in the design of wireless sensor
networks. This work presents Scheduled on Demand Radio WakeUp (SORW), a
flexible scheduler designed for a wireless sensor network where duty cycling strategy
and radio wake-up technology are combined in order to optimize the network
lifetime. In particular, it tries to keep sensors sleeping as much as possible, still
guaranteeing a minimum number of detections per unit of time. Performances
of SORW are provided through the use of OMNet++ simulator and compared
to results obtained by other basic approaches. Results show that with SORW it
is possible to reach a theoretical lifetime of several years, compared to simpler
schedulers that only reach days of activity of the network.
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Hardiman, Brady S. "Resilience of Forest Carbon Storage through Disturbance and Succession." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339686584.
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Friedl, Johannes. "Denitrification losses from intensively managed pastures in the subtropics: Key controls and mitigation." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/108060/1/Johannes_Friedl_Thesis.pdf.
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Intensively managed pastures receive high inputs of nitrogen via fertiliser application, but inefficiencies result in large losses of nitrogen to the environment. This project identified the microbial process of soil denitrification as a major pathway of nitrogen loss from subtropical pastures, establishing the agronomic and environmental significance of denitrification losses for these agroecosystems.
This research shows how soil water management and enhanced efficiency fertiliser can be combined to reduce denitrification losses from pasture soils. This strategy to improve nitrogen use efficiency provides both mitigation and productivity benefits and represents a win-win scenario for the future management of intensively managed pastures.
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Figueira, Thiago Gomes. "Efeitos fisiológicos do treinamento unipodal em cicloergômetro com e sem irradiação LED." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-20082018-153447/.
Full textAbstract:
A melhora na capacidade física e/ou reserva funcional de um indivíduo deve-se, entre outros, a um treinamento sistemático e bem padronizado. O exercício aeróbio é uma modalidade frequentemente empregada em um programa de treinamento, especialmente naqueles com objetivo de melhora do condicionamento físico. Contudo atualmente, o uso da fototerapia tem ganhado espaço no que tange ao aumento de desempenho de atletas. Baseado nisso o objetivo deste estudo foi verificar o efeito do treinamento unipodal, terapia LED e treinamento associado à terapia LED sobre parâmetros ergoespirométricos de performance (VO2max, AT e RCT) e na concentração sanguínea de creatina quinase. Para esse estudo participaram 24 voluntários do sexo masculino, os quais foram submetidos a uma avaliação pré-intervenção, foram submetidos a um período de oito semanas de treinamento em cicloergômetro com irradiação LED ou placebo. Após esse período foram submetidos a uma nova avaliação, pós-treino. Para a aplicação da terapia LED, foi utilizado um arranjo contendo 50 LEDs com comprimento de onda de 850 nm e aplicado por 60 segundos após cada sessão de treino. Os voluntários foram separados nos seguintes grupos experimentais: Não Treinados e LED desligado (Grupo NTLD), Não Treinados e LED ligado (Grupo NTLL), Treinados e LED desligado (Grupo TLD), Treinados e LED ligado (Grupo TLL). A perna que recebeu a intervenção foi eleita por sorteio e foi chamada de perna ativa (A) e a perna contralateral, chamada de controle (C). Durante o teste em exercício crescente, até a fadiga, foram quantificadas as variáveis ergoespirométricas, ventilação (Ve), consumo de oxigênio (VO2), equivalente ventilatório de oxigênio (EqVO2), também foi coletada amostra de sangue para dosagem da lactacidemia e foi mensurada a concentração da enzima creatina quinase (CK). Como resultados das respostas agudas frente ao ato de pedalar com uma perna notou-se que a pedalada unipodal apresentou menor valor de intensidade, VO2, Ve, lactacidemia e maior incremento de CK, quando comparada com a pedalada bipodal (convencional). Ao se concluir as oito semanas de treinamento notou-se que a perna ativa na pedalada unipodal apresentou melhoras nas variáveis mensuradas nos grupos TLL, NTLL e algumas no TLD. Também foi encontrada melhora para a perna controle, em algumas variáveis, dos grupos que receberam a terapia LED. Com esse estudo conclui-se que o treinamento unipodal é capaz de melhorar parâmetros como intensidade, ventilação, consumo de oxigênio, eficiência aeróbia, e ainda minimiza os danos musculares induzido pelo exercício no membro que efetuou o treinamento. A terapia LED é capaz de promover as mesmas melhoras em intensidades, consumo de oxigênio e eficiência aeróbia que o treinamento proporcionou, contudo em magnitudes diferentes, ainda é capaz de proporcionar efeito protetor contra lesão muscular induzida pelo exercício. A terapia LED associada ao treinamento potencializa os efeitos conseguidos com cada um isoladamente.The improvement in physical capacity and/or functional reserve is due to, among other factors, a systematic and organized training program. Aerobic exercise is a frequently used modality in a training program, especially among those who aim to improve physical fitness. However phototherapy has currently gained space in regard to improving the performance of athletes. Based on this information, the purpose of the study was to verify the effect of one-legged cycling, LED therapy and their association on ergospirometric parameters of performance (VO2max, AT and RCT) and on blood concentration of CK. 24 male subjects volunteered for the study and were submitted to a pre-intervention evaluation and an 8-week period of one-legged cycling with LED therapy or placebo. After the intervention period subjects were submitted to a second evaluation. An arrangement containing 50 LEDs and a wavelength of 850 nm was applied during 60 seconds after each training session. Volunteers were divided into the following experimental groups: untrained and LED off (ULOf), untrained and LED on (ULOn), trained and LED off (TLOf) and trained and LED on (TLOn). The leg that received the intervention (training and/or LED therapy) was selected randomly and named active leg (A) and the contralateral limb was named control (C). During the incremental exercise test to volitional failure the ergospirometric variables ventilation (Ve), oxygen uptake (VO2) and oxygen ventilatory equivalent (EqVO2) were measured and blood samples were collected after each stage for lactate and before and 24 hours after the test for the analysis of blood CK. Acute responses from the pre-intervention evaluation showed that the intensity of one-legged cycling led to lower intensity, VO2, Ve, blood lactate and higher increase in blood CK compared to traditional cycling (two-legged). After the 8 weeks of intervention, the active leg showed improvements in the measured variables for the TLOn, ULOn and TLOf groups and, in some of the variables for the groups that received LED therapy. With these data we conclude that one-legged cycling is capable of increasing parameters such as intensity, ventilation, oxygen uptake, aerobic efficiency and minimizes the blood CK responses to exercise in the exercised limb. The association between exercise and Led therapy potentiates the effects achieved with either of the interventions.
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Goodrich-Stuart, Ellen. "Forest Net Primary Production Resistance Across a Gradient of Moderate Disturbance." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/627.
Full textAbstract:
The global carbon (C) balance is vulnerable to disturbances that alter terrestrial C uptake and loss. Moderate disturbances that kill or defoliate only a subset of canopy trees such as insect defoliation, drought, and age-related senescence are increasing in extent and frequency; yet, little is known about the effect of moderate disturbance on forest production and the mechanisms sustaining or supporting the recovery of the C cycle across a range of moderate disturbance severities. We used a broad plot-scale gradient of upper canopy tree mortality within a large manipulation of forest disturbance to: 1) quantify how aboveground wood net primary production (ANPPw) responds to a range of moderate disturbance severities and; 2) identify the primary mechanisms supporting ANPPw resistance or resilience following moderate disturbance. We found that ANPPw was highly resistant to moderate disturbance, with production levels sustained following the senescence of 9 to > 60 % of the upper canopy tree basal area. As upper canopy gap fraction increased with rising disturbance severity, greater light availability to the subcanopy enhanced leaf-level C uptake and the growth of this formerly light-limited canopy stratum, compensating for upper canopy production losses. As a result, whole-ecosystem production efficiency (ANPPw/LAI) increased at high levels of disturbance severity and leaf area loss. These findings provide a mechanistic explanation for sustained ANPPw across the disturbance gradient, in which the physiological and growth enhancement of undisturbed vegetation was proportional to the level of disturbance severity. Our results have important ecological and management implications, showing that moderate disturbances may minimally alter ecosystem functions such as C storage.
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Wang, Lingjuan. "Theoretical study of cyclone design." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2192.
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To design a cyclone abatement system for particulate control, it is necessary to accurately estimate cyclone performance. In this cyclone study, new theoretical methods for computing travel distance, numbers of turns and cyclone pressure drop have been developed. The flow pattern and cyclone dimensions determine the travel distance in a cyclone. The number of turns was calculated based on this travel distance. The new theoretical analysis of cyclone pressure drop was tested against measured data at different inlet velocities and gave excellent agreement. The results show that cyclone pressure drop varies with the inlet velocity, but not with cyclone diameter. Particle motion in the cyclone outer vortex was analyzed to establish a force balance differential equation. Barth??s "static particle" theory, particle (with diameter of d50) collection probability is 50% when the forces acting on it are balanced, combined with the force balance equation was applied in the theoretical analyses for the models of cyclone cut-point and collection probability distribution in the cyclone outer vortex. Cyclone cut-points for different dusts were traced from measured cyclone overall collection efficiencies and the theoretical model for calculating cyclone overall efficiency. The cut-point correction models (K) for 1D3D and 2D2D cyclones were developed through regression fit from traced and theoretical cut-points. The regression results indicate that cut-points are more sensitive to mass median diameter (MMD) than to geometric standard deviation (GSD) of PSD. The theoretical overall efficiency model developed in this research can be used for cyclone total efficiency calculation with the corrected d50 and PSD. 1D3D and 2D2D cyclones were tested at Amarillo, Texas (an altitude of 1128 m / 3700 ft), to evaluate the effect of air density on cyclone performance. Two sets of inlet design velocities determined by the different air densities were used for the tests. Experimental results indicate that optimal cyclone design velocities, which are 16 m/s (3200 ft/min) for 1D3D cyclones and 15 m/s (3000 ft/min) for 2D2D cyclones, should be determined based on standard air density. It is important to consider the air density effect on cyclone performance in the design of cyclone abatement systems.
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Vincent, Raymond A. Jr. "Efficiency analysis of the cyclone separator using CFD techniques." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17372.
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Adebare, Adedeji. "Optimizing the efficiency of cylindrical cyclone gas/liquid separators for field applications." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4417.
Full textAbstract:
Problems associated with the use of compact cylindrical cyclone gas/liquid (CCGL)
separators can be attributed to two physical phenomena: gas carry-under and liquid carryover
(LCO). Inadequate understanding of the complex multiphase hydrodynamic flow
pattern inside the cylindrical separator has inhibited complete confidence in its design
and use, hence the need for more research.
While many works have been done with a fixed inlet slot to predict the operational
efficiency of the cyclone separator, very little is known about how separator performance
can be influenced due to changes in fluid properties. During the operations of the CCGL
separator the complex flow situations arising from severe foaming within the separator
has not been addressed. Also the effects of emulsion formation under three phase flow
conditions on the properties of cyclone separators are yet to be studied.
An understanding of liquid holdup and hydrodynamic nature of flow in a compact
separator under zero net liquid flow (ZNLF) and zero net gas flow (ZNGF) conditions is
necessary in many field applications, especially for the prediction of LCO and in the
design of the CCGL separators. Also, ZNLF holdup is an important parameter in
predicting bottom-hole pressures in pumping oil wells.
This research investigated the effects of fluid properties such as density, foam and
emulsion formation on ZNLF, zero net gas flow ZNGF, and LCO in compact cyclone
separators; this was achieved by replacing water, which is the conventional fluid used as
the liquid medium in many previous research efforts with a foamy oil while maintaining
air as the gas phase. Variable-inlet-slots that regulate the artificial gravity environment
created by the separator were used to check for improved separator performance. Also experiments to check separator response to a range of water-cut in three-phase flow were
performed. All experiments were carried out under low constant separator pressures.
The ZNLF holdup is observed to decrease as the density of the fluid medium
decreases. Varying the inlet slot configurations and recombination points does not have
any effect on the ZNLF holdup when changes in density of the liquid phase occur.
Comparisons with previous work show that there exists a wide variation in the LCO
operational envelope when severe foaming occurs in the CCGL separator. At high watercut
(greater than 30%), the separator LCO performance was observed to be normal.
However, at water-cut below 30%, LCO was initiated much earlier; this is attributed to
severe foaming in the CCGL separator.
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Lans, Patrik. "Numerical Methods for Simulating Separation in a Vacuum Cleaner Cyclone." Thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-194498.
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This thesis includes a numerical comparison of different turbulence models and particle models in terms of convergence time and physical accuracy. A cyclone is used as the computational domain. Cyclones are common devices for separating two or more substances. The work is divided into an experimental part and a numerical part. In the experiments, characteristics of the cyclone were measured. This data is then used to evaluate different numerical modeling approaches. The numerical part consists of two parts, namely single phase flow and multiphase flow, where different modeling aspects are examined and presented. Furthermore, important parameters that characterize a cyclone, such as pressure drop and separation efficiency, are calculated. The separation efficiency, i.e. how much dust that actually goes to the dust bin, is calculated for two different types of dust. The software used for the numerical simulations has been Star-CCM+.
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Pažourek, Josef. "Cyklonový odlučovák pro velmi malé částice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417432.
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This thesis deals with really small cyclone separators which could be used for a flue gas purification. The search section discusses particle formation in combustion, their characteristics, any other flue gas cleaning options and last but not least, a cyclone separator where is the effort to understand all the influences that contribute to a cyclone’s resulting separability. The Experimental section analyses a calculation of the cyclone and theoretical separability, a verification of this separability using a cyclone created by a 3D printer. On the one hand, the verification was made by gravimetric analysis which is intended for a bigger particles, on the second hand, it was made using the PALAS which is aimed at particles in µm. There is also a comparison of theoretical and measured values in this section.
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Kunapareddy, Naveen. "A Proof-of-Concept Test for Seperation Efficiency of an Electro-Cyclone." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1237569168.
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Titscher, Thomas. "Efficient computational mesoscale modeling of concrete under cyclic loading." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667647.
Full textAbstract:
Concrete is a complex material and can be modeled on various spatial and temporal scales. While simulations on coarse scales are practical for engineering applications, a deeper understanding of the material is gained on finer scales. This is at the cost of an increased numerical effort that can be reduced by the three methods developed and used in this work, each corresponding to one publication.
The coarse spatial scale is related to fully homogenized models. The material is described in a phenomenological approach and the numerous parameters sometimes lack a physical meaning. Resolving the three-phase mesoscopic structure consisting of aggregates, the mortar matrix and the interfaces between them allow to describe similar effects with simpler models. This work addresses two computational challenges related to mesoscale modeling.
First, aggregate particles take up a high volume fraction and an efficient particle-packing algorithm is required to generate non-overlapping, random esostructures. Enforcing an additional distance between the aggregates is essential to obtain undistorted meshes for finite element simulations, but further complicates the packing problem. An event-driven molecular-dynamics algorithm is applied to this problem that, in contrast to traditional methods, allows movement and a dense arrangement of the aggregates. This allows creating concrete mesostructures with realistic aggregate volume fractions.
The second challenge concerns stability problems in mesoscale simulations of concrete fracture. The geometric complexity and the combination of three material laws for each of the phases leads to numerical instabilities, even for regularized material models. This requires tiny time steps and numerous iterations per time step when integrated with a classic backward Euler scheme. The implicit–explicit (IMPL-EX) integration extrapolates internal variables that account for the nonlinear behavior. This linearizes the equations, provides additional robustness and a computational speedup. In combination with a novel time step control method, a three-dimensional mesoscale compression test is accelerated by a factor of 40, compared to an adaptive backward Euler algorithm.
The life time of concrete under cyclic loads is commonly predicted with empirical Wöhler lines. They relate the number of endured cycles with the applied load amplitude and can be included in constitutive formulations. They can, however, hardly be generalized to geometries and load configurations other than the ones tested.
On a finer temporal scale, fatigue failure is modeled by the accumulation of damage within each loading cycle. This resolves the whole process of failure, includes stress redistributions and size effects and can easily be extended to multiphysics phenomena.
The third computational challenge solved here is the efficient temporal integration that would not be feasible in a naive cycle-by-cycle integration of thousands or millions of cycles. The cost of evaluating a single cycle is reduced by reformulating the problem in the frequency space. It is sufficient to equilibrate the structure once for each Fourier coefficient which significantly speeds up this evaluation. The accumulated damage of one cycle is integrated in time using an adaptive cycle jump concept. For a two dimensional void test structure, the combination of both techniques leads to a 25 times faster simulation compared to the full integration.
These three main contributions decrease the numerical cost of mesoscale simulations, allow larger and more detailed models and are a basis to deepen the understanding of the complex failure patterns in concrete.El hormigón es un material complejo y puede ser modelado en varias escalas espaciales y temporales. Mientras que las simulaciones en escalas gruesas son prácticas para aplicaciones de ingeniería, se obtiene una comprensión más profunda del material en escalas más finas. Esto es a costa de un mayor esfuerzo numérico que puede ser reducido por los tres métodos desarrollados y utilizados en este trabajo, cada uno de los cuales corresponde a una publicación. La escala espacial gruesa está relacionada con modelos totalmente homogeneizados. El material se describe con un enfoque fenomenológico y los numerosos parámetros a veces carecen de significado físico. La resolución de la estructura mesoscópica trifásica formada por los áridos, la matriz de mortero y las interfaces entre ellos permite describir efectos similares con modelos más sencillos. Este trabajo aborda dos retos computacionales relacionados con el modelado a mesoescala. En primer lugar, las partículas agregadas absorben una fracción de gran volumen y se requiere un algoritmo eficiente de empaquetamiento de partículas para generar mesoestructuras aleatorias que no se solapen. Hacer cumplir una distancia adicional entre los agregados es esencial para obtener mallas no distorsionadas para simulaciones de elementos finitos, pero complica aún más el problema de empaquetado. A este problema se le aplica un algoritmo de dinámica molecular impulsado por eventos que, a diferencia de los métodos tradicionales, permite el movimiento y una disposición densa de los agregados. Esto permite crear mesoestructuras de hormigón con fracciones de volumen de agregado realistas. El segundo reto se refiere a los problemas de estabilidad en las simulaciones mesoescalares de fracturas de hormigón. La complejidad geométrica y la combinación de tres leyes materiales para cada una de las fases conduce a inestabilidades numéricas, incluso para modelos materiales regularizados. Esto requiere pequeños pasos de tiempo y numerosas iteraciones por paso de tiempo cuando se integra con un esquema clásico de Euler hacia atrás. La integración implícita- explícita (IMPL-EX) extrapola variables internas que dan cuenta del comportamiento no lineal. Esto linealiza las ecuaciones, proporciona robustez adicional y una aceleración computacional. En combinación con un nuevo método de control de paso en el tiempo, una prueba de compresión tridimensional de mesoescala es acelerada por un factor de 40, en comparación con un algoritmo adaptativo de Euler hacia atrás. La vida útil del hormigón bajo cargas cíclicas se predice comúnmente con las líneas empíricas de Wöhler. Relacionan el número de ciclos soportados con la amplitud de carga aplicada y pueden ser incluidos en formulaciones constitutivas. Sin embargo, difícilmente pueden generalizarse a geometrías y configuraciones de carga distintas a las probadas. En una escala temporal más fina, la falla por fatiga es modelada por la acumulación de daño dentro de cada ciclo de carga. Esto resuelve todo el proceso de fracaso, incluye redistribuciones de estrés y efectos de tamaño, y puede extenderse fácilmente a fenómenos multifísicos. El tercer reto computacional resuelto aquí es la integración temporal eficiente que no sería factible en una integración costosa de miles o millones de ciclos ciclo a ciclo. El costo de evaluar un solo ciclo se reduce reformulando el problema en el espacio de frecuencias. Es suficiente equilibrar la estructura una vez para cada coeficiente de Fourier, lo que acelera significativamente esta evaluación. El daño acumulado de un ciclo se integra en el tiempo utilizando un concepto de salto de ciclo adaptativo. Para una estructura de prueba de vacío bidimensional, la combinación de ambas técnicas conduce a una simulación 25 veces más rápida en comparación con la integración completa.
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Kegg, Steve W. "A Numerical Investigation of Gas Cyclone Separation Efficiency with Comparison to Experimental Data and Presentation of a Computer-Based Cyclone Design Methodology." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1216912969.
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Yusuf, Ahmed A. "The study of down-hole hydro-cyclone efficiency in oil wells using computational fluid dynamics." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4886.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains ix, 64 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 63-64).
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Alfarah, Bashar. "Advanced computationally efficient modeling of RC structures nonlinear cyclic behavior." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/454783.
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Under severe seismic excitation, structural behavior of buildings and other constructions is highly complex. It involves, among other issues, soil-structure interaction, large strains and displacements, damage, plasticity, and near-collapse behavior. Moreover, in reinforced concrete structures, there are several coupled degradation and failure modes: cracking, crushing and spalling of concrete, yielding and pull-out of tensioned reinforcement, yielding and buckling of compressed reinforcement. Furthermore, another circumstance makes the situation more alarming: given the increasing awareness and concern on the huge worldwide seismic risk, earthquake engineering has experienced in last years substantial advances. New design and analysis strategies have been proposed, leading to relevant developments. These developments rely on extensive testing and numerical simulation mainly based on oversimplified models referred in this work as structural component-based models, as a result of their moderate computational cost. Therefore, there is a strong need of verifying the reliability of the new developments by comparison with analyses performed using more advanced simulation tools and with experiments. This work is organized in two parts. First part presents an accurate model, while the second part deals with a more simplified model, although highly computational efficient. First part. This research clarifies the aforementioned issues by developing a new continuum mechanics-based model for simulating the monotonic and cyclic behavior of reinforced concrete structures. The developed model combines a new methodology for calculating the damage variables in Concrete Plastic Damage Models "CPDM", and a new approach to integrate CPDM with a 3-D interface bond-slip model developed by other researchers. A new scheme to implement the interface model in a continuum FEM model of regions with crossing reinforcement bars is also presented in this research. Mesh-insensitivity, accuracy and reliability of the proposed model are verified by simulating several monotonic and cyclic tests; the obtained results are compared with experimental ones, satisfactory agreement has been accomplished. Second part. The developed model is the First Part is compared with simplified structural component-based models that are commonly used in earthquake engineering; results has shown the superiority of the proposed model to predict the actual behavior of highly damaged RC elements and frames, capturing strength reduction, stiffness degradation and pinching phenomena. However, some of the structural component-based models have shown an acceptable performance considering the law computationally cost in comparison with the advanced continuum mechanics-based model. After this conclusion, this part presents a numerical study on the relation among the non-simulated deterioration modes of the elements in non-ductile RC frames and their final capacity. A structural component-based model has been developed for simulating the nonlinear dynamic behavior of non-ductile reinforced structures, accounting for flexure, shear and axial deterioration modes. The developed model is numerically efficient, thus being suitable for day use in earthquake engineering. The capacity of the developed model is verified by simulating the nonlinear dynamic behavior of an existing non-ductile building and the prototype building. Obtained results shows that the developed model, despite its moderate computational cost, detects and reproduces accurately the nonlinear dynamic behavior of non-ductile RC structures, as well, capturing the deterioration modes that are blind to the simplified models. Comparison with results from more simplified models highlights the importance of hidden failure modes in the behavior of each element and in the overall collapse mechanisms. The relation between the non-simulated failure modes and the so-called "Structural Resurrection" is addressedEl comportamiento estructural de edificios y otras construcciones bajo severas excitaciones sísmicas es muy complejo e implica temas como, la interacción suelo-estructura, grandes esfuerzos y desplazamientos, daños, plasticidad y el comportamiento de la estructura cerca del colapso. Por otra parte, en estructuras de hormigón armado, existen varios modos de fallo y de degradación: agrietamiento, aplastamiento y desprendimiento del hormigón, plastificación y extracción de las armaduras traccionadas y plastificación y pandeo de las armaduras comprimidas. Además, otras circunstancias hacen que la situación sea más alarmante: dada la creciente conciencia y preocupación por el enorme riesgo sísmico mundial, la ingeniería sísmica ha experimentado en los últimos años avances sustanciales, para lo cual se han propuesto nuevas estrategias de análisis y diseño, lo que conduce a desarrollos relevantes. Estos desarrollos se basan en pruebas y simulaciones numéricas basadas principalmente en modelos simplificados referidos en este trabajo como modelo basados en la estructura, resultando un costo computacional moderado. Por lo tanto, existen una gran necesidad de verificar la fiabilidad de los nuevos desarrollos en comparación con los análisis realizados utilizando herramientas de simulación más avanzadas y con ensayos. Este trabajo se organiza en dos partes; en la primera se describe un modelo preciso basado en la mecánica del medio continuo y en la segunda se presenta otro modelo más simplificado basado en los componentes de la estructura. Primera parte. En esta parte se desarrolla un nuevo modelo basado en la mecánica del medio continuo para simular el comportamiento monotónico y cíclico de estructuras de hormigón armado. El modelo desarrollado combina una nueva metodología para el cálculo de las variables del daño en el Modelo de Daño Plástico del Hormigón “CPDM”, y un nuevo enfoque para integrar el CPDM con un modelo de interface de 3-D desarrollado en otra investigación. También se presenta un nuevo esquema para implementar la interfaz del modelo en un modelo FEM continuo de regiones con armaduras que se cruzan en varias direcciones. La precisión, la fiabilidad y la insensibilidad a la malla del modelo propuesto se verifican simulando varias pruebas incrementales y cíclicas; los resultados obtenidos se comparan con experimentales, lográndose un ajuste satisfactorio. Segunda parte. El modelo desarrollado in el Primer Parte ha sido comparado con modelos simplificados basados en los componentes estructurales de uso común en la ingeniería sísmica, los resultados mostraron la superioridad del modelo pro-puesto para predecir el comportamiento real de los elementos y pórticos RC altamente dañados, capturando la reducción de la resistencia, la degradación de la rigidez y el efecto pinzamiento (“pinching”). Sin embargo, algunos de los modelos basados en componentes estructurales han mostrado un desempeño aceptable teniendo en cuenta el costo computacional de la ley en comparación con el modelo avanzado basado en la mecánica del medio continuo. Con de esta conclusión, este parte de este trabajo presenta un estudio numérico sobre la relación entre los modos de deterioro no-simulados de pórticos de hormigón sin ductilidad y su capacidad última. Se ha desarrollado un modelo avanzado basado en los componentes de la estructura para simular el comportamiento dinámico no lineal de las estructuras sin ductilidad, teniendo en cuenta los modos de deterioro de flexión, corte y axial. El modelo desarrollado es numéricamente eficiente, siendo pues adecuado para el uso profesional en ingeniería sísmica. La capacidad del modelo desarrollado se verifica mediante la simulación del comportamiento dinámico no lineal de un edificio no dúctil existente y del edificio prototipo.
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Tom, Caroline Carleton University Dissertation Engineering Electronics. "Investigation and implementation of computationally-efficient algorithm for cyclic spectral analysis." Ottawa, 1995.
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Björk, Erik. "Energy Efficiency Improvements in Household Refrigeration Cooling Systems." Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93061.
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This thesis is based on eight articles all related to the characteristics of the cooling system and plate evaporator of a household refrigerator. Through these articles, knowledge is provided that can be used to increase the operational efficiency in household refrigeration. Papers A, B and C focus on heat transfer and pressure drop in a commonly used free convection evaporator – the plate evaporator. Applicable correlations are suggested on how to estimate the air side heat transfer, the refrigerant side pressure drop and the refrigerant side heat transfer. Papers D, E and F hold a unique experimental study of the refrigerant charge distribution in the cooling system at transient and steady state conditions. From this cyclic losses are identified and estimated and ways to overcome them are suggested. In paper G the topic “charging and throttling” is investigated in an unparalleled experimental study based on more than 600 data points at different quantities of charge and expansions device capacities. It results in recommendations on how to optimize the capillary tube length and the quantity of refrigerant charge. Finally, Paper H holds a thermographic study of the overall cooling system operating at transient conditions. Overall, a potential to lower the energy use by as much as 25 % was identified in the refrigerator studied. About 10 % was found on the evaporator’s air side. 1-2 % was identified as losses related to the edge effect of the evaporator plate. About 8 % was estimated to be cyclic losses. About 5 % was found in cycle length optimization. It is believed that most of these findings are of general interest for the whole field of household refrigeration even though the results come from one type of refrigerator. Suggestions of simple means to reduce the losses without increasing the unit price are provided within the thesisQC 20120411
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Lagemann, Benjamin. "Efficient seakeeping performance predictions with CFD." Thesis, KTH, Marina system, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261772.
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With steadily increasing computational power, computational fluid dynamics (CFD) can be applied to unsteady problems such as seakeeping simulations. Therefore, a good balance between accuracy and computational speed is required. This thesis investigates the application of CFD to seakeeping performance predictions and aims to propose a best-practice procedure for efficient seakeeping simulations. The widely used KVLCC2 research vessel serves as a test case for this thesis and FINEŠ/Marine software package is used for CFD computations. In order to validate the simulations, results are compared to recent experimental data from SSPA as well as predictions with potential ˛ow code SHIPFLOW® Motions. As for the calm water simulations, both inviscid and viscous ˛ow computations are performed in combination with three mesh refinement levels. Seakeeping simulations with regular head waves of different wavelengths are set-up correspondingly. Furthermore, different strategies for time discretization are investigated. With the given computational resources, it is not feasible to complete seakeeping simulations with a ˝ne mesh. However, already the coarse meshes give good agreement to experiments and SHIPFLOW® Motions' predictions. Viscous ˛ow simulations turn out to be more robust than Euler ˛ow computations and thus should be preferred. Regarding the time discretization, a fixed time discretization of 150 steps per wave period has shown the best balance between accuracy and speed. Based on these findings, a best-practice procedure for seakeeping performance predictions in FINEŠ/Marine is established. Taking the most efficient settings obtained from head wave simulations, the vessel is subjected to oblique waves with 160° encounter angle. Under similar wave conditions, CFD predictions of a similar thesis show close agreement in terms of added wave resistance. Compared to the previous head wave conditions of this study, added resistance in 160° oblique waves is found to be significantly higher. This underlines that oblique bow quartering waves represent a relevant case for determining the maximum required power of a ship. CFD and potential ˛ow show similar accuracy with respect to ship motions and added wave resistance, albeit potential ˛ow outperforms CFD in terms of computational speed. Hence, CFD should be applied in cases where viscous effects are known to have large influence on a vessel's seakeeping behavior. This can be the case if motion control and damping devices are to be evaluated, for instance.Tack vare den stadigt ökande beräkningskraften kan beräkningsuiddynamik (CFD) idag användas på beräkningsintensiva problem som sjöegenskapssimulationer. Den här rapporten undersöker användning av CFD på sjöegenskapsprestanda och syftar till att foreslå ett best-practice förfaringssätt för effektiv sjöegenskapssimulationer. Forskningsskrovet KVLCC2 fungerar som ett testfall för denna rapport och FINE/Marine-mjukvarupaketet används för CFD-beräkningar. Viktiga parametrar, såsom ödestyp, beräkningsnät och tidssteg varierars systematiskt. Resultaten jämförs med experiment gjorda vid SSPA. Baserat på resultaten förelås en best-practice. Den föreslagna best-practice användas vidare för berökningar av sjöegenskaper i sneda vågor. Jämförelse av resultaten med liknande studier visar god överensstämmelse. Genom att använda det föreslagna förfarandet för best-practice kan CFD-sjöegenskapssimulationer användas på fall där viskösa krafter måste beaktas, till exempel rörelseregleringsanordningar.
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Sami, Abdul Wahab. "Area Efficient ADC for Low Frequency Application." Thesis, Linköpings universitet, Elektroniska Kretsar och System, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-117413.
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Analog to digital converters (ADCs) are the fundamental building blocks in communication systems. The need to design ADCs, which are area and/or power efficient, has been common. Various ADC architectures, constrained by resolution capabilities, can be used for this purpose. The cyclic algorithmic architecture of ADC with moderate number of bits comes out to be probably best choice for the minimum area implementation. In this thesis a cyclic ADC is designed using CMOS 65 nm technology. The ADC high-level model is thoroughly explored and its functional blocks are modelled to attain the best possible performance. In particular, the nonlinearities which affect the cyclic/algorithmic converter are discussed. This ADC has been designed for built-in-self-testing (BiST) on a chip. It is only functional during the testing phase, so power dissipation is not a constraint while designing it. As it is supposed to be integrated as an extra circuitry on a chip, its area really matters. The ADC is designed as 10-bit fully differential switch-capacitor (SC) circuit using 65nm CMOS process with 1.2V power supply. A two stage Operational Transconductance Amplifier (OTA) is used in this design to provide sufficient voltage gain. The first stage is a telescopic OTA whereas the second is a common source amplifier. The bottom plate sampling is used to minimize the charge injection effect which is present in the switches.
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Kasarabada, Yasaswy. "A Verilog Description and Efficient Hardware Implementation of the Baillie-PSW Primality Test." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1471347471.
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Olagunju, Moses Oladipo. "A study of efficient recovery of liquid from fine air-liquid mists of the form generated in gas turbine bearing chambers using rotating porous disc." Thesis, University of East London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265060.
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Lazarevic, Ljubica. "Improving the efficiency and accuracy of nocturnal bird Surveys through equipment selection and partial automation." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4155.
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Birds are a key environmental asset and this is recognised through comprehensive legislation and policy ensuring their protection and conservation. Many species are active at night and surveys are required to understand the implications of proposed developments such as towers and reduce possible conflicts with these structures. Night vision devices are commonly used in nocturnal surveys, either to scope an area for bird numbers and activity, or in remotely sensing an area to determine potential risk. This thesis explores some practical and theoretical approaches that can improve the accuracy, confidence and efficiency of nocturnal bird surveillance. As image intensifiers and thermal imagers have operational differences, each device has associated strengths and limitations. Empirical work established that image intensifiers are best used for species identification of birds against the ground or vegetation. Thermal imagers perform best in detection tasks and monitoring bird airspace usage. The typically used approach of viewing bird survey video from remote sensing in its entirety is a slow, inaccurate and inefficient approach. Accuracy can be significantly improved by viewing the survey video at half the playback speed. Motion detection efficiency and accuracy can be greatly improved through the use of adaptive background subtraction and cumulative image differencing. An experienced ornithologist uses bird flight style and wing oscillations to identify bird species. Changes in wing oscillations can be represented in a single inter-frame similarity matrix through area-based differencing. Bird species classification can then be automated using singular value decomposition to reduce the matrices to one-dimensional vectors for training a feed-forward neural network.
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SUMIYA, LUIZ C. do A. "Estudo de parâmetros relevantes na irradiação de sup(124)Xe, visando a otimização na obtenção de sup(123)I ultra puro no ciclotron cyclone-30 IPEN-CNEN/SP." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11477.
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Made available in DSpace on 2014-10-09T12:52:20Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:00:49Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Thakkar, Amit. "Combinatorial Synthesis, Sequencing, and Biological Applications of Peptide and Peptidomimetic Libraries." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259775104.
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Kolios, Grigorios [Verfasser], and Gerhart [Akademischer Betreuer] Eigenberger. "Regenerative fixed-bed processes : approximative analysis and efficient computation of the cyclic steady state / Grigorios Kolios. Betreuer: Gerhart Eigenberger." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/1058106260/34.
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Dudal, Clément. "Forme d'onde multiporteuse pour de la diffusion par satellite haute capacité." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/8342/1/dudal.pdf.
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Cette thèse se concentre sur l’amélioration conjointe de l'efficacité spectrale et de l'efficacité en puissance de schémas de transmission par satellite. L’émergence de nouveaux services et l'augmentation du nombre d’acteurs dans le domaine nécessitent de disposer de débits de plus en plus importants avec des ressources de plus en plus limitées. Les progrès réalisés ces dernières années sur la technologie embarquée et dans le domaine des communications numériques permettent de considérer des schémas de transmission à plus haute efficacité spectrale et en puissance. Cependant, l’enjeu majeur des schémas de transmission proposes actuellement reste de rentabiliser les ressources disponibles. L’étude développée dans cette thèse explore les possibilités d’amélioration conjointe de l’efficacité spectrale et de l’efficacité en puissance en proposant la combinaison de la modulation Cyclic Code-Shift-Keying (CCSK), dont l’efficacité en puissance augmente avec l’élévation du degré de la modulation, avec une technique de multiplexage par codage de type Code-Division Multiplexing (CDM) pour pallier la dégradation de l’efficacité spectrale liée à l’étalement du spectre induit par la modulation CCSK. Deux approches basées sur l’utilisation de séquences de Gold de longueur N sont définies: Une approche multi-flux avec un décodeur sphérique optimal en réception. La complexité liée à l’optimalité du décodeur conduit à des valeurs d'efficacité spectrale limitées mais l’étude analytique des performances, vérifiée par des simulations, montre une augmentation de l'efficacité en puissance avec l'efficacité spectrale. Une approche mono-flux justifiée par l’apparition de redondance dans les motifs résultant du multiplexage des séquences. L’approche mono-flux propose des valeurs d’efficacité spectrale équivalente aux schémas retenus dans le standard DVB-S2 avec une amélioration de l’efficacité en puissance à partir d’un certain seuil de rapport signal à bruit par rapport à ces schémas. Par la suite, l'étude porte sur la transposition de plusieurs symboles de modulation sur les porteuses d’un système OFDM et sur les bénéfices et avantages d’une telle approche. Elle se conclut sur l’apport d’un codage canal basé sur des codes par bloc non binaires Reed-Solomon et LDPC. La forme d’onde proposée offre des points de fonctionnement à haute efficacité spectrale et haute efficacité en puissance avec des perspectives intéressantes. Dans le contexte actuel, son application reste limitée par ses fluctuations d’amplitude mais est envisageable dans un contexte de transmission multiporteuse, comme attendu dans les années à venir.