Dissertations / Theses: 'Full Hybrids'

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Voigt, Robert L., and Carl L. Schmalzel. "Grain Sorghum Hybrids Grown Full Season at the Safford Agricultural Center, 1984." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/200530.

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Shaw, Ivan Ting-kun 1966. "Unique immunologic determinants of neuroblastoma x spinal cord cell hybrids." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26142.

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The cell biology of the motor neuron--the cell targeted in amyotrophic lateral sclerosis and other human neurodegenerative diseases--is not well understood, partially since little is known of the molecules defining its phenotype. Using the motor neuron-like somatic cell hybrid NSC$ sb{34}$ (Cashman et al. 1992), we developed a panel of polyclonal antibodies recognizing unique epitopes on this cell line. Screening of a preliminary panel demonstrated that virtually all surface epitopes were shared with the N18TG2 neuroblastoma parent but following absorption of the antisera with N18TG2 cells, hybrid-specific surface reactivity was observed. A second panel generated in animals tolerized to N18TG2 showed similar hybrid-specific reactivity without requiring preabsorption. Immunoblotting revealed several unique NSC$ sb{34}$ bands ranging in size from 40 kDa to over 120 kDa, as well as several bands shared with N18TG2; parallel blots showed that these were not NCAM or neurofilament subunits. This antiserum also recognized epitopes of NG108-15 cells (Nirenberg et al. 1983) induced into a motor neuronal phenotype, suggesting that some of the NSC$ sb{34}$ gene products have a role in motor neuron function. Digestion of cell homogenates with endoglycosidases prior to immunoblotting eliminated the NSC$ sb{34}$ reactivity, suggesting that all unique NSC$ sb{34}$ epitopes (including those cross-reactive with induced NG108-15) were localized to glycoconjugates. Our work indicates that it is possible to characterize the molecules of the motor neuron phenotype, but that the focus may have to shift from searching for unique proteins to unique glycoconjugates or (protein)-carbohydrate combinations.

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Yazbeck, Daniel Rida. "Molecular requirements for degradation of RNA in DNARNA hybrids by ribonuclease H." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33046.

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The Ribonuclease H (RNase H) family of enzymes selectively degrades the RNA strand of DNA/RNA hybrids. Using a sense strand which contained the minimum natural RNA gap requirement, the kinetic rates of degradation of a series of heteroduplex substrates containing 2'F-ANA antisense oligonucleotides of variable flexibility were examined. Results from these studies implicate flexibility of the antisense oligonucleotides as a major requirements for RNase H catalytic efficiency. In addition to the above, physicochemical studies have revealed the thermal stabilities and relative conformations of these modified heteroduplexes under physiological conditions. All of the above findings offer further insights into the physical binding and catalytic properties of the RNase H-substrate interaction, and have been incorporated into a revised model for the mechanism of action of this crucial enzyme. (Abstract shortened by UMI.)

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Begna, Sultan Hussein. "Agronomic and physiological aspects of competition for light between corn hybrids differing in canopy architecture and weeds." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35572.

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The problems associated with short growing seasons has led to the development of leafy-reduced stature (LRS) corn hybrids. These hybrids have more leaf area above the ear, more rapid leaf area development, shorter stature, earlier maturity, and better responses to high plant populations and narrow spacings than conventional hybrids. Plants grown in a reduced light environment are limited in carbon assimilation and this, in turn, results in reductions in growth and development. A way to supplement the availability of photosynthate is injection of sucrose into plant stems. The objective of this thesis was to determine the ability of LRS corn plants to compete with weeds, and the reactions of weed species to the shade, including the relationships between weed growth (increase in biomass) and development (shape) under shaded conditions. Three years of field experiments (LRS and more conventional corn hybrids with both transplanted and naturally growing weeds) and two years of greenhouse work [weeds alone, C3 (lamb's quarters and velvetleaf) and C4 (redroot pigweed) in full sun or deep (75%) shade injected with 15% sucrose or not] were conducted. Yield reductions due to weed pressure were lower for LRS than other hybrids. Biomass production by both transplanted and naturally occurring weeds was up to 85% less under corn canopies than when grown without competition from corn. The biomass of C4 weeds was more reduced by competition with corn plants than that of C3 weeds. In spite of quick and early leaf development, leaves and other plant parts of LRS were not damaged excessively by mechanical (rotary hoeing) weed control. Both C3 and C4 weed plants produced more dry matter when injected with sucrose. Dry weights of sucrose injected shaded plants were not different from full sun uninjected plants. However, sucrose injection did not alter shading effects on development (distribution of biomass). Dry matter production and photosynthetic rates of C4 weeds were more reduced

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Polius, J. J. N. "Micronutrient nutrition of maize (Zea mays L.) as influenced by fertilizers, hybrids, irrigation and plant population density." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63809.

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Liu, Aiguo 1949. "Mycorrhizal symbiosis and nutrient uptake in new maize hybrids with contrasting phenotypes as influenced by soil phosphorus level." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36820.

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Development and functioning of arbuscular mycorrhizal (AM) symbiosis in the soil-plant system are required in sustainable agriculture. AM development of maize genotypes and uptake of nutrients as influenced by soil P levels were studied. Several experiments were conducted both in the greenhouse and in the field. In greenhouse trials, pasteurized substrates were inoculated with Glomus intraradices as mycorrhizal treatments. Mycorrhizal development varied widely among maize hybrids and inbreds. Leafy normal stature (LNS) had the highest root colonization and shoot:root ratio and was the most responsive to AM fungi. Mycorrhizal development was generally reduced at high soil P and micronutrient levels. The percentage of root colonization was correlated with the ratio of plant tissue N/P only when soil N level was intermediate. Mycorrhizal plants increased uptake of Zn and Cu only at low P and low micronutrient levels, but decreased Mn uptake at higher micronutrient level. In field trials, soil fumigation was used to eliminate AM fungi in control plots. Again LNS was most responsive to indigenous AM fungi, closely followed by Non-leafy normal stature (NLNS). Mycorrhizae increased uptake of K, Ca and Mg only when these nutrients and available P were low in soil. Correlations between extraradicular hyphae and plant concentrations of K, Ca and Mg suggested that uptake of K was more dependent on extraradicular hyphae than uptake of Ca and Mg. Total P uptake was higher in plots where the AM symbiosis was not repressed, but soil available P was not always reduced. There is potential for development of mycorrhiza efficient maize hybrids performing well under low input management in sustainable agriculture.

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Modarres, Sanavy S. A. M. (Seyed Ali Mohammad). "Leafy reduced-stature maize (Zea mays L.) for mid- to short-season environments : yield, development, and physiological aspects of inbred lines and hybrids." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39966.

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Maize production in short-season environments has at least two critical problems. Firstly, maize grown in short-season areas has lower leaf area indices (LAI) than maize grown in long season areas, due to shorter plant stature and less time for development, which results in reduced leaf number and size. Secondly, in very short-season areas the seasonal thermal-time available may be insufficient to mature grain of current maize hybrids. Therefore development of maize types that accumulate leaf area and mature quickly would increase production of maize in mid- to short-season areas. The leafy (Lfy1) and reduced-stature (rd1) genes make contributions to this end. However, these two genes have not previously been combined. From 1991 to 1993, field experiments were conducted to evaluate the leafy reduced-stature (LRS) inbred lines and hybrids for yield, maturity times and morphological traits, at different planting densities and patterns in Montreal and Ottawa. LRS maize inbred lines showed the most rapid silk extrusion, optimum leaf area development, and rapid growth of the first ear, the highest yield per unit leaf area, and the closest synchronization of pollen shed and silk extrusion at high plant population densities. LRS maize hybrids had the most rapid leaf development, longest grain filling period, lowest grain moisture content at harvest, and highest harvest index. Therefore LRS hybrids should allow an extension into shorter season areas where it can not now be successfully cultivated, and may increase yields in mid- to short season areas where maize is now produced.

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Begna, Sultan Hussein. "Response of leafy reduced-stature maize (Zea mays L.) hybrids to plant population densities and planting patterns in a short-season area." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27278.

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The yield of short-season hybrids is lower than long-season hybrids, mainly as a result of the low final leaf area developed by the short-season plants. This is due to the smaller plant stature and smaller leaf number and size of short-season adapted hybrids. In addition, in short-season areas the thermal-time available may be insufficient to mature grain of current maize hybrids. Maize hybrids which accumulate leaf area quickly, mature earlier, yield well and tolerate higher population densities better than the currently available hybrids would be more suitable for production in short-season areas. The "Leafy reduced-stature" maize hybrids, which have only recently been developed, have traits which address these criteria. There has been no previous effort to evaluate the effects of more than two plant population densities or the effects of planting patterns on the yield, yield components and vegetative growth of these hybrids. in 1995, field experiments were conducted at two sites near Montreal to compare the response of leafy reduced-stature (LRS), non-leafy normal stature (NLNS), and non-leafy reduced-stature (NLRS) maize hybrids to plant population densities and planting patterns. LRS maize hybrids showed the most rapid growth of the first ear, and the highest yield per single plant and per hectare at high plant population densities in paired rows. LRS hybrids also had longer grain filling periods, lower grain moisture contents and higher harvest indices than conventional (NLNS) hybrids. Rapid growth of the first ear and a higher harvest index are indications that LRS hybrids should be more tolerant of higher population densities than currently available hybrids. Therefore, LRS hybrids show promise for production in short-season areas at high plant population densities where maize cultivation is not currently economical due to shortness of the growing-season.

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Rémillard, Michel. "Effect of hybrids, plant populations, rates of fertilizer and irrigation on soil test levels, field and nutrient uptake with corn (Zea mays L.) in Quebec." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61270.

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The purpose of this study was to investigate the effect of maize (Zea mays L.) hybrids, plant population, rates of fertilization and irrigation in 1984 and 1985 on soil test levels, soil pH, yield and yield components as well as nutrient uptake. High rates of fertilization increased soil test P and K but decreased soil test Ca and Mg and soil pH. Irrigation decreased soil test K, Ca and Mg. In both years maximum grain yields (at 15.5% moisture) were obtained when all factors were at high levels. Hybrid Pioneer 3925 and and hybrid CO-OP 2645 produced a maximum yield of 11.9 and 15.2 Mg ha$ sp{-1}$ in 1984 and 1985, respectively. Increasing plant population alone increased grain yield from 9.6 to 10.4 Mg ha$ sp{-1}$ in 1984, bu increases in grain yield with high plant population in 1985 could only be obtained when high rate of nutrients and supplemental irrigation were applied. Nutrient uptake was usually greater for hybrid 2645 than hybrid 3925 in 1985, and greater for hybrid 3925 than for hybrid 3949 in 1984. Increasing plant population, rate of fertilization as well as available soil moisture generally brought about greater nutrient uptake. Ear leaf nutrient concentration at silking time was influenced by these factors but the differences obtained were not agronomically significant.

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Zhou, Yang. "Predictive energy management for fuel cell hybrid electric vehicle." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCA020.

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Les véhicules électriques hybrides à pile à combustible ont été largement considérés comme la substitution prometteuse par rapport aux véhicules traditionnels à moteur à combustion interne. Pour réduire les coûts d'exploitation des véhicules, une solution pratique au stade actuel consiste à utiliser efficacement et sainement les systèmes de propulsion hybrides. Une telle tâche peut être remplie via des stratégies de gestion d'énergie fiables, qui coordonnent les sorties de plusieurs sources d'énergie pour satisfaire la demande de puissance des véhicules.Dans un tel contexte, cette thèse vise à concevoir des stratégies de gestion intelligente de l'énergie pour les véhicules électriques hybrides à pile à combustible. Par rapport aux stratégies de contrôle existantes, cette thèse se concentre particulièrement sur la possibilité de combiner les informations de conduite prévues avec le cadre de contrôle optimal en temps réel. Plusieurs techniques de prédiction de conduite sont développées pour estimer les conditions de conduite à venir, comme la vitesse du véhicule, la référence de l’état de charge de la batterie et les informations sur le modèle de conduite. Ensuite, la model predictive control est sélectionnée pour la prise de décision en temps réel, car elle est capable de gérer les systèmes contraints variant dans le temps et est pratique pour l'intégration des informations prédictives de pilotage. Sur la base des résultats prévus et model predictive control, plusieurs stratégies de gestion prédictive de l'énergie sont établies, visant à économiser la consommation d'hydrogène et à améliorer la durabilité des piles à combustible par rapport aux stratégies de référence.La simulation hors ligne et les tests logiciels en boucle ont vérifié la fonctionnalité et l'adéquation en temps réel des stratégies proposées Fuel cell electric vehicles have been widely deemed as the promising substitution against traditional internal combustion engine-based vehicles. To reduce the vehicular operating costs, a practical solution at current stage is to efficiently and healthily use the hybrid propulsion systems. Such task can be fulfilled via reliable energy management strategies, which coordinate the outputs of multiple energy sources to satisfy the vehicular power request.In such context, this PhD thesis intends to devise intelligent energy management strategies for fuel cell hybrid electric vehicles. Compared to existing control strategies, this thesis especially focuses on the possibility of combining the forecasted driving information with the real-time optimal control framework. Several driving prediction techniques are developed to estimate the upcoming driving conditions, like the vehicle’s speed, battery state-of-charge reference and driving pattern information. Thereafter, model predictive control is selected for real-time decision-making, since it is capable of handling the time-varying constrained systems and is convenient for the integration of driving predictive information. Based on the forecasted results and model predictive control, several predictive energy management strategies are established, aiming at saving hydrogen consumption and enhancing fuel cell durability versus benchmark strategies.Both offline simulation and software-in-the-loop testing have verified the functionality and real-time suitability of the proposed strategies

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Namakian, Mohsen. "Mild Hybrid System in Combination with Waste Heat Recovery for Commercial Vehicles." Thesis, Linköpings universitet, Maskinkonstruktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-93997.

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Performance of two different waste heat recovery systems (one based on Rankine cycle and the other one using thermoelectricity) combined with non-hybrid, mild-hybrid and full hybrid systems are investigated. The vehicle under investigation was a 440hp Scania truck, loaded by 40 tons. Input data included logged data from a long haulage drive test in Sweden.All systems (waste heat recovery as well as hybrid) are implemented and simulated in Matlab/Simulink. Almost all systems are modeled using measured data or performance curves provided by one manufacturer. For Rankine system results from another investigation were used.Regardless of practical issues in implementing systems, reduction in fuel consumption for six different combination of waste heat recovery systems and hybrid systems with different degrees of hybridization are calculated. In general Rankine cycle shows a better performance. However, due to improvements achieved in laboratories, thermoelectricity could also be an option in future.This study focuses on “system” point of view and therefore high precision calculations is not included. However it can be useful in making decisions for further investigations.

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Romero, Alessandro Gerlinger. "Hybrid fuml: a hybrid synchronous language." Instituto Nacional de Pesquisas Espaciais (INPE), 2014. http://urlib.net/sid.inpe.br/plutao/2014/11.13.11.40.

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A noção de um sistema híbrido é centrada em torno de uma composição de comportamentos discretos e contínuos, Enquanto a dificuldade na modelagem de sistemas híbridos vem da diversidade destes sistemas, a mais promissora abordagem para mitigar este problema é desenvolver linguagens de modelagem expressivas e precisas. No entanto, desenvolver linguagens de modelagem expressivas e precisas não significa a necessidade de novas linguagens, pelo contrário, esta tese propõe semânticas precisas para subconjuntos de linguagens existentes. Subconjuntos são definidos porque expressividade e precisão geralmente conflitam. por exemplo, o tamanho e a complexidade de uma linguagem (relacionados à expressividade) podem ter consequências diretas no tamanho e complexidade de sua semântica (relacionados à precisão). Precisão significa uma semântica definida de acordo com um método formal estabelecido, além disso, reconhecendo a natureza de tempo real dos sistemas híbridos, a linguagem de modelagem deve permitir determinismo, previsibilidade e composição simples. Nesta tese, duas linguagens complementares são formalmente definidas por máquinas de estado abstrato (A8Ms). A primeira delas é chamada synchronous fUML e ela combina recursos síncronos para controle na fUML (foundational subset for- executable UML models) padronizada. A segunda delas, Hybrid fUML, é uma extensão conservativa da synchronous fUML, na qual equações algébrico-diferenciais (DAEs) são descritas usando-se um subconjunto da sintaxe concreta da Modelica, O subconjunto da Modelica é selecionado de tal forma que sua semântica é definida pela semântica matemática padrão. Hybrid fUML é uma linguagem de modelagem definida para permitir descrição e análise de visões sistêmicas de sistemas híbridos. A principal contribuição inovadora é o novo modelo de computação para extensões híbridas de linguagens síncronas, que é formalmente definido para Hybrid fUML. O novo modelo de computação é baseado no conceito enichrony, uma propriedade de modelos que permite a sincronização do tempo físico no ambiente e nos modelos. O novo modelo da computação permite determinismo, previsibilidade e composição simples de sistemas híbridos. The notion of a hybrid system is centered around a composition of discrete and continuous behaviors. Although the difficulty in modeling hybrid systems comes from the diversity of these systems, the most promising approach to mitigate this issue is developing expressive and precise modeling languages. Nevertheless, developing expressive and precise modeling languages does not necessarily mean the emergence of a new language, on the contrary, this thesis proposes precise semantics for subsets of existent languages. Subsets of existent languages are defined since expressivity and precision usually conflict, e.g., the size and complexity of a language (related to expressivity) may have direct consequences on the size and complexity of its semantics (related to precision). Precision means a semantics defined according to a well stablished formal method, furthermore, recognizing the real-time nature of hybrid systems, the modeling language have to enable determinism, predictability and straightforward composition. In this thesis, two complementary languages are formally defined by abstract state machines (ASMs). The first one is called synchronous fUML and it blends synchronous features for control into the standardized fUML (foundational subset for executable UML models). The second one, hybrid fUML, is a conservative extension of synchronous fUML in which differential algebraic equations (DAEs) are described using a subset of Modelica concrete syntax. The subset of Modelica concrete syntax is selected in such a way that its semantics is defined by the standart mathematical semantics. Hybrid fUML is a modeling language defined to enable description and analysis of system views from hybrid systems. The main innovative contribution lies in the novel model of computation for hybrid extensions of synchronous languages, which is formally defined for hybrid fUML. The novel of computation enables determinism, predictability and straightforward composition of hybrid systems.

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Vobecký, Jan. "Analýza současného vývoje elektromobility, porovnání různých druhů pohonů." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-446744.

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The diploma thesis focuses on the analysis of the current development of electromobility and the description of different types of drives. The first part deals with the basic theory of electric vehicles on batteries, hybrid vehicles and fuel cell vehicles. The second part provides analysis and data on the offered electric cars. At the end of the work is an evaluation of the situation.

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Méaux, Pierrick. "Hybrid fully homomorphic framework." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEE066/document.

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Le chiffrement complètement homomorphe est une classe de chiffrement permettant de calculer n’importe quelle fonction sur des données chiffrées et de produire une version chiffrée du résultat. Il permet de déléguer des données à un cloud de façon sécurisée, faire effectuer des calculs, tout en gardant le caractère privé de ces données. Cependant, l’innéficacité actuelle des schémas de chiffrement complètement homomorphes, et leur inadéquation au contexte de délégation de calculs, rend son usage seul insuffisant pour cette application. Ces deux problèmes peuvent être résolus, en utilisant ce chiffrement dans un cadre plus large, en le combinant avec un schéma de chiffrement symétrique. Cette combinaison donne naissance au chiffrement complètement homomorphe hybride, conçu dans le but d’une délégation de calculs efficace, garantissant des notions de sécurité et de vie privée. Dans cette thèse, nous étudions le chiffrement complètement homomorphe hybride et ses composantes, à travers la conception de primitives cryptographiques symétriques rendant efficace cette construction hybride. En examinant les schémas de chiffrement complètement homomorphes, nous developpons des outils pour utiliser efficacement leurs propriétés homomorphiques dans un cadre plus complexe. En analysant différents schémas symétriques, et leurs composantes, nous déterminons de bons candidats pour le contexte hybride. En étudiant la sécurité des constructions optimisant l’évaluation homomorphique, nous contribuons au domaine des fonctions booléennes utilisées en cryptologie. Plus particulièrement, nous introduisons une nouvelle famille de schémas de chiffrement symétriques, avec une nouvelle construction, adaptée au contexte hybride. Ensuite, nous nous intéressons à son comportement homomorphique, et nous étudions la sécurité de cette construction. Finalement, les particularités de cette famille de schémas de chiffrement motivant des cryptanalyses spécifiques, nous développons et analysons de nouveaux critères cryptographiques booléens Fully homomorphic encryption, firstly built in 2009, is a very powerful kind of encryption, allowing to compute any function on encrypted data, and to get an encrypted version of the result. Such encryption enables to securely delegate data to a cloud, ask for computations, recover the result, while keeping private the data during the whole process. However, today’s inefficiency of fully homomorphic encryption, and its inadequateness to the outsourcing computation context, makes its use alone insufficient for this application. Both of these issues can be circumvented, using fully homomorphic encryption in a larger framework, by combining it with a symmetric encryption scheme. This combination gives a hybrid fully homomorphic framework, designed towards efficient outsourcing computation, providing both security and privacy. In this thesis, we contribute to the study of hybridfully homomorphic framework, through the analysis, and the design of symmetric primitives making efficient this hybrid construction. Through the examination of fully homomorphic encryption schemes, we develop tools to efficiently use the homomorphic properties in a more complex framework. By investigating various symmetric encryption schemes, and buildingblocks up to the circuit level, we determine good candidates for a hybrid context. Through evaluating the security of constructions optimizing the homomorphic evaluation, we contribute to a wide study within the cryptographic Boolean functions area. More particularly, we introduce a new family of symmetric encryption schemes, with a new design, adapted to the hybrid fully homomorphic framework. We then investigate its behavior relatively to homomorphic evaluation, and we address the security of such design. Finally, particularities of this family of ciphers motivate specific cryptanalyses, therefore we develop and analyze new cryptographic Boolean criteria

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Joseph, Krishna Sathyamurthy. "Hybrid direct methanol fuel cells." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44777.

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A new type of fuel cell that combines the advantages of a proton exchange membrane fuel cells and anion exchange membrane fuel cells operated with methanol is demonstrated. Two configurations: one with a high pH anode and low pH cathode (anode hybrid fuel cell (AHFC)),and another with a high pH cathode and a low pH anode (cathode hybrid fuel cell (CHFC)) have been studied in this work. The principle of operation of the hybrid fuel cells were explained. The two different hybrid cell configurations were used in order to study the effect of the electrode fabrication on fuel cell performance. Further, the ionomer content and properties such as the ion exchange capacity and molecular weight were optimized for the best performance. A comparison of the different ionomers with similar properties is carried out in order to obtain the best possible ionomer for the fuel cell. An initial voltage drop was observed at low current density in the AHFC, this was attributed to the alkaline anode and the effect of the ionomers with the new cationic groups were studied on this voltage drop was studied. These ionomers with the different cationic groups were studied in the CHFC design as well. Finally, the use of non platinum catalyst cathode with the CHFC design was also demonstrated for the first time.

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Wu, Zhe. "Hybrid Beamforming Design for Full-Duplex mmWave Relaying Systems." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284250.

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With the tremendous growth in the mobile data traffic, the demand for highdata rate is increasing rapidly, and higher frequency resources shall be exploredto alleviate the congestion in the overcrowded spectrum, thus, the millimeterwave (mmWave) frequency resource ranging from 30 GHz to 300 GHz has beenrecognized as a nature fit for the fifth-generation (5G) and beyond network. Tocompensate the severe path-loss in the mmWave band as well to realize theefficient transmissions by applying the low-cost architecture, it is of intereststo investigate the beamforming schemes with large-scale antenna arrays andthe full-duplex (FD) relaying strategy, which are indispensable in the operationof directional signal transmission and the efficient spectrum utilization inthe mmWave transmission, respectively. However, the self-interference (SI)occurring between the separate antenna arrays is the main impediment inrealizing a FD wireless node while considering the simultaneous transmission andreception.This thesis project aims to design efficient hybrid beamforming algorithms toimprove spectral efficiency and eliminate SI. The orthogonal matching pursuit(OMP)-based hybrid analog-digital beamforming design, and the alternatingdirection method of multipliers (ADMM)-based schemes are explored to improvethe spectral efficiency and eliminate the SI in this work. Moreover, a fast ADMMenabledhybrid precoding approach with SI cancellation is proposed to achievethe efficient performance and superior convergence compared with the existingschemes, as it is verified by the presented numerical simulations. Med den enorma tillväxten i den mobila datatrafiken ökar efterfrågan påhög datahastighet snabbt, och högre frekvensresurser ska undersökas för attminska trängseln i det överbefolkade spektrumet, vilket innebär att Volymvågens(mmwave) frekvensresurs, som sträcker sig från 30 GHz till 300 GHz, har erkäntssom en naturlig resurs för den femte generationen (5G) och utanför nätverket.För att kompensera den allvarliga förlusten av tågläge i mmwave-bandet ochför att förverkliga de effektiva sändningarna genom att tillämpa den billigaarkitekturen.Det är av intresse att undersöka strålformningsprogrammen medstorskaliga antennmatriser och strategin för återutläggning av hela duplex (FD),som är oumbärliga för att driva den direkta signal överföringen och det effektivaspektrumutnyttjandet i mmwave-transmissionen.separata antennmatriser är etthuvudhinder för att förverkliga en trådlös nod från FD samtidigt som manöverväger samtidig överföring och mottagning.Syftet med detta avhandlingsprojekt är att utforma effektiva kombineradestrålformningsinformationsalgoritmer för att förbättra spektraleffektiviteten ocheliminera SI. Den ortogonala matchande jakten (OMP)-baserad hybrid analogdigitalstrålformning, och metoden med alternerande riktning för multiplikatorer(ADMM)-baserade system utforskas för att förbättra spektraleffektiviteten ochelimineraSI i det här arbetet. Dessutom föreslås en snabb, adMM-aktiveradhybrid förkonditionering med SI-annullering för att uppnå effektiv prestandaoch överlägset konvergens jämfört med de befintliga systemen, eftersom denkontrolleras av de presenterade numeriska simuleringarna.

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Smith, Thomas Paul. "Hardware Simulation of Fuel Cell / Gas Turbine Hybrids." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14581.

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Hybrid solid oxide fuel cell / gas turbine (SOFC/GT) systems offer high efficiency power generation, but face numerous integration and operability challenges. This dissertation addresses the application of hardware-in-the-loop simulation (HILS) to explore the performance of a solid oxide fuel cell stack and gas turbine when combined into a hybrid system. Specifically, this project entailed developing and demonstrating a methodology for coupling a numerical SOFC subsystem model with a gas turbine that has been modified with supplemental process flow and control paths to mimic a hybrid system. This HILS approach was implemented with the U.S. Department of Energy Hybrid Performance Project (HyPer) located at the National Energy Technology Laboratory. By utilizing HILS the facility provides a cost effective and capable platform for characterizing the response of hybrid systems to dynamic variations in operating conditions. HILS of a hybrid system was accomplished by first interfacing a numerical model with operating gas turbine hardware. The real-time SOFC stack model responds to operating turbine flow conditions in order to predict the level of thermal effluent from the SOFC stack. This simulated level of heating then dynamically sets the turbine's "firing" rate to reflect the stack output heat rate. Second, a high-speed computer system with data acquisition capabilities was integrated with the existing controls and sensors of the turbine facility. In the future, this will allow for the utilization of high-fidelity fuel cell models that infer cell performance parameters while still computing the simulation in real-time. Once the integration of the numeric and the hardware simulation components was completed, HILS experiments were conducted to evaluate hybrid system performance. The testing identified non-intuitive transient responses arising from the large thermal capacitance of the stack that are inherent to hybrid systems. Furthermore, the tests demonstrated the capabilities of HILS as a research tool for investigating the dynamic behavior of SOFC/GT hybrid power generation systems.

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Doerner, Karl, Richard F. Hartl, and Marc Reimann. "A hybrid ACO algorithm for the full truckload transportation problem." SFB Adaptive Information Systems and Modelling in Economics and Management Science, WU Vienna University of Economics and Business, 2001. http://epub.wu.ac.at/74/1/document.pdf.

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In this paper we propose a hybrid ACO approach to solve a full truckload transportation problem. Hybridization is achieved through the use of a problem specific heuristic. This heuristic is utilized both, to initialize the pheromone information and to construct solutions in the ACO pro-cedure. The main idea is to use information about the required fleetsize, by initializing the system with a number of vehicles rather than opening vehicles one at a time as needed. Our results show the advantages of this new approach over more traditional, i.e. sequential, approaches. Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

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Sheu, Elysia J. (Elysia Ja-Zeng). "Hybrid solar-fossil fuel power generation." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78189.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012. Cataloged from PDF version of thesis. Includes bibliographical references (p. 83-92). In this thesis, a literature review of hybrid solar-fossil fuel power generation is first given with an emphasis on system integration and evaluation. Hybrid systems are defined as those which use solar energy and fuel simultaneously, thus excluding the viable alternative of solar thermal plants which use fossil fuels as backup. The review is divided into three main sections: performance metrics, the different concentrated solar receiver technologies and their operating conditions, and the different hybridization schemes. In addition, a new linear combination metric for analysis of hybrid systems, which considers trade-off of different metrics at the fleet level, is presented. This metric is also compared to alternative metrics from multi-objective optimization. Some previous work only evaluates the hybrid cycle at a certain point in time, which can be misleading as this evaluation would not take into account certain aspects of hybrid cycle such as fluctuating solar supply. Furthermore, almost all previous work designs the hybrid solar-fossil fuel systems for a certain point in time and then evaluates the performance of the system for an entire year. By not taking into account fluctuating solar supply and selling price of electricity in the design of the system, the best possible annual performance of the hybrid cycle may not be reached. Second, an analysis of solar reforming as the integration method for the hybrid cycle is presented, in particular steam reforming of methane. Two solar reforming systems are analyzed: one with a parabolic trough and the other with a solar tower. From the analysis, it is determined that parabolic troughs are not suitable for steam reforming due to the relatively low operating temperatures. The tower reformer system is integrated with a standard combined cycle, and the design and operation of the hybrid cycle is optimized for highest work output for a fixed fuel input and solar collector area (essentially optimizing for maximum cycle efficiency). A heuristic two step procedure is used for the optimization due to the limitation of the optimizer which cannot simultaneously optimize both design and operation. From the optimization, it is determined that the tower reforming integration method is a promising integration option in that this type of hybrid cycle yields high incremental solar efficiencies and also satisfies the linear combination metric for efficiency and CO₂ emissions (i.e., the analyzed hybrid cycle has a higher efficiency for a fixed CO₂ emissions compared to a linear combination of solar only and fossil fuel only cycles). by Elysia J. Sheu. S.M.

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Marc, Nicolas. "Méthodologie de dimensionnement d’un véhicule hybride électrique sous contrainte de minimisation des émissions de CO2." Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2078/document.

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Ce travail de thèse propose une méthodologie systématique d’évaluation et de comparaison des gains en émissions de CO2 de véhicules hybrides électriques de différentes architectures et intégrant différentes fonctionnalités. Une méthodologie de dimensionnement a été mise en place, elle se base sur la définition d’un cahier des charges en performances dynamiques des véhicules, la mise en place d’algorithmes de mise à l’échelle afin de générer les données des composants de la chaîne de traction (batterie, machine électrique, moteur thermique), et l’utilisation de procédures de dimensionnement du véhicule sous contrainte de minimisation des émissions de CO2. L’évaluation énergétique des différentes configurations de véhicule ainsi dimensionnées s’articule autour de la définition de différents usages du véhicule et sur l’implémentation d’une loi de gestion optimale de l’énergie de type Principe du Minimum de Pontriaguine. Ces méthodologies ont été appliquées à une architecture conventionnelle, servant de référence pour les performances dynamiques et les consommations énergétiques, et d’une architecture hybride parallèle pré-transmission, pour laquelle une configuration hybride rechargeable et une configuration hybride non rechargeable ont été implémentées This thesis work proposes a systematic methodology dedicated to the evaluation and comparison of CO2 emissions’ reduction for hybrid electric vehicles with different architectures and different levels of functionality. A sizing methodology has been developed, which is based on the definition of the requirements for the dynamic performances of vehicles, on the development of scaling algorithms in order to generate the dataset for the powertrain components (battery, electric motor, engine), and on the application of procedures for the sizing of a vehicle under CO2 emissions’ minimization constraint. The energy consumption evaluation of the different vehicle configurations, which were previously sized, is founded on the definition of a variety of vehicle’s type of use, as well as on the implementation of an optimal energy management strategy, the Pontryaguin’s Minimum Principle. These methodologies have been applied to a conventional vehicle architecture, which has been used as a reference for dynamic performances and energy consumption, and to a hybrid parallel pre-transmission architecture, which has been defined in two configurations, a plug-in hybrid and a non plug-in full-hybrid

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Fontaine, Clément. "Supervision optimale des véhicules électriques hybrides en présence de contraintes sur l’état." Thesis, Valenciennes, 2013. http://www.theses.fr/2013VALE0024.

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La propulsion des véhicules électriques hybrides parallèles est généralement assurée par un moteur à combustion interne combiné à une machine électrique réversible. Les flux de puissance entre ces deux organes de traction sont déterminés par un algorithme de supervision, qui vise à réduire la consommation de carburant et éventuellement les émissions de certains polluants. Dans la littérature, la théorie de la commande optimale est maintenant reconnue comme étant un cadre puissant pour l’élaboration de lois de commande pour la gestion énergétique des véhicules full-hybrides. Ces stratégies, dénommée « Stratégies de Minimisation de la Consommation Equivalente » (ECMS) sont basée sur le principe du Maximum de Pontryagin. Pour démontrer l’optimalité de l’ECMS, on doit supposer que les limites du système de stockage ne sont pas atteintes durant le cycle de conduite. Il n’est plus possible de faire cette hypothèse lorsque l’on considère les véhicules micro et mild hybrides étudiés dans cette thèse car la variable d’état atteint généralement plusieurs fois les bornes. Des outils mathématiques adaptés à l’étude des problèmes de commande avec contraintes sur l’état sont présentés et appliqués à deux problèmes en lien avec la gestion énergétique. Le premier problème consiste à déterminer le profil optimal de la tension aux bornes d’un pack d’ultra-capacités. Le second problème se concentre sur un système électrique intégrant deux stockeurs. L’accent est mis sur l’étude des conditions d’optimalités valables lorsque les contraintes sur l’état sont actives. Les conséquences de ces conditions pour la commande en ligne sont mises en avant et exploitées afin de concevoir une commande en temps réel. Les performances sont évaluées à l’aide d’un prototype. Une comparaison avec une approche de type ECMS plus classique est également présentée Parallel hybrid electric vehicles are generally propelled by an internal combustion engine, which is combined to a reversible electric machine. The power flows between these two traction devices are determined by a supervisory control algorithm, which aims at reducing the fuel consumption and possibly some polluting emissions. In the literature, optimal control theory is now recognized as a powerful framework for the synthesis of energy management strategies for full hybrid vehicles. These strategies are referred to as “Equivalent Consumption Minimization Strategies” (ECMS) and are based on the Pontryagin Maximum Principle. To demonstrate the optimality of ECMS, it must be assumed that the storage system limits are not reached during the drive cycle. This hypothesis cannot be made anymore when considering the micro and mild hybrid vehicles studied in this thesis because the state variable generally reaches several times the boundaries. Some mathematical tools suitable for the study of state constrained optimal control problems are introduced and applied to two energy management problems. The first problem consists in determining the optimal profile of the voltage across a pack of ultra-capacitors. The second problem focuses on a dual storage system. The stress is put on the study of the optimality conditions holding in case of active state constraints. Some consequences of these conditions for the online control are pointed out are exploited for the design of a real-time controller. Its performances are assessed using a demonstrator vehicle. A comparison with a classical ECMS-based approach is also provided

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Platt, Kyle. "DESIGN AND FABRICATION OF A FULL-FEATURED LABSCALE HYBRID ROCKET ENGINE." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2815.

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The design, development, integration and testing of a full-featured, Lab-Scale Hybrid Rocket Engine was not only envisioned to be the chosen method of putting student payloads into space, but to be an invaluable teaching resource. The subject of the present thesis is the analysis, design, development, integration and demonstration of a lab-scale hybrid rocket motor. The overarching goal of this project was to establish a working developmental lab model from which further research can be accomplished. The lab model was specifically designed to use a fuel source that could be studied in normal laboratory conditions. As such, the rocket engine was designed to use Hydroxyl Terminated Polybutadiene as the fuel and Liquid Nitrous Oxide as the oxidizer. Developing the rocket engine required the usage of several electronics modules and a software package. The custom-designed electronics modules were a Signal Conditioning & Data Amplification Interface and a Data Acquisition Network. The software package was coded in Visual Basic (VB). A MathCAD regression rate computer model was designed and written to geometrically constrain the engine design. Further, the computer model allowed for the "what-if" situations to be evaluated. Using ProPep, solutions to the Equilibrium Thermodynamics Equations for the fuel and oxidizer mixture were obtained. The resultants were used as initial input to the computer model for predicting the lab-scale rocket's Chamber Pressure, Chamber Temperature, Ratio of Specific Heats and Molecular Weight. Details on the model, the rocket hardware, and the successful test firing are provided. M.S.A.E. Department of Mechanical, Materials and Aerospace Engineering; Engineering and Computer Science Aerospace Engineering

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Bilen, Cagdas. "A Hybrid Approach For Full Frame Loss Concealment Of Multiview Video." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608559/index.pdf.

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Multiview video is one of the emerging research areas especially among the video coding community. Transmission of multiview video over an error prone network is possible with efficient compression of these videos. But along with the studies for efficiently compressing the multiview video, new error concealment and error protection methods are also necessary to overcome the problems due to erroneous channel conditions in practical applications. In packet switching networks, packet losses may lead to block losses in a frame or the loss of an entire frame in an encoded video sequence. In recent years several algorithms are proposed to handle the loss of an entire frame efficiently. However methods for full frame losses in stereoscopic or multiview videos are limited in the literature. In this thesis a stereoscopic approach for full frame loss concealment of multiview video is proposed. In the proposed methods, the redundancy and disparity between the views and motion information between the previously decoded frames are used to estimate the lost frame. Even though multiview video can be composed of more than two views, at most three view are utilized for concealment. The performance of the proposed algorithms are tested against monoscopic methods and the conditions under which the proposed methods are superior are investigated. The proposed algorithms are applied to both stereoscopic and multiview video.

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Meneghini, Orso (Orso-Maria Cornelio). "Full-wave modeling of lower hybrid waves on Alcator C-Mod." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76501.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2012. Cataloged from PDF version of thesis. Includes bibliographical references (p. 225-237). This thesis focuses on several aspects of the Lower Hybrid (LH) wave physics, the common theme being the development of full-wave simulation codes based on Finite Element Methods (FEM) used in support of experiments carried out on the Alcator C-Mod tokamak. In particular, two non-linear problems have been adressed: high power antenna-plasma coupling and current drive (CD). In both cases, direct solution of the wave equation allowed testing the validity of approximations which were historically done and consider full-wave effects and realistic geometries. The first code, named POND, takes into account the interaction of high power LH waves and the plasma edge based on the non-linear ponderomotive force theory. Simulations found the effect of ponderomotive forces to be compatible with the density depletion which is measured in front of the antenna in presence of high power LH waves. The second code, named LHEAF, solves the problem of LH wave propagation in a hot non- Maxwellian plasma. The electron Landau damping (ELD) effect was expressed as a convolution integral along the magnetic field lines and the resultant integro-differential Helmholtz equation was solved iteratively. A 3D Fokker-Planck code and a synthetic Hard X-Ray (HXR) diagnostic modules are used to calculate the self-consistent electron distribution function and evaluate the resulting CD and bremsstrahlung radiation. LHEAF has been used to investigate the anomalous degradation of LHCD efficiency at high density. Results show that while a small fraction of the launched power can be absorbed in the SOL by collisions, it is a strong upshift in the nii spectrum that makes the overall LHCD efficiency low by allowing the waves to Landau damp near the edge. Wavelet analysis of the full-wave fields identified spectral broadening to occur after the waves reflect and propagate in the SOL. This work explains why on Alcator C-Mod the eikonal approximation is valid only in the low to moderate density regime, and why parasitic phenomena introduced in previous work can reproduce phenomenologically well the experimental results. by Orso Meneghini. Ph.D.

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Voigt, Robert L., and Carl L. Schmalzel. "Corn Hybrid Grain Yields from Full Season Growth at Safford, Arizona." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/200532.

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Sandoval, torres Cinda Luz. "Contrôle d’une source d’énergie hybride : Pile à combustible-Supercondensateur." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0067/document.

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Cette thèse s’inscrit dans le cadre de conception d’une stratégie de gestion de l’énergie dans un système hybride de génération d'énergie électrique composé d’une pile à combustible (PC) et un module de supercondensateurs (SC). La source hybride fournit une puissance maximale de 1,2 kW et sa conception implique des décisions concernant la sélection de l’architecture du système hybride ainsi que le choix de la topologie et le dimensionnement d’une unité de convertisseurs. La stratégie de gestion vise à satisfaire la demande d’énergie électrique de la charge et favoriser la consommation énergétique efficiente ; sa performance est évaluée en développant un simulateur qui comprend la dynamique des éléments mis en jeu : deux sources et l’unité de convertisseurs. Le générateur hybride est supposé alimenter un profil de consommation correspondant à un véhicule électrique, de ce fait un cycle standard de conduite en ville en échelle est demandé lors des simulations, ce qui permet d’évaluer la performance du générateur hybride et plus spécifiquement de la stratégie de gestion énergétique.Dans une première étape de cette thèse, un simulateur intégral a été construit avec des librairies de Simscape. Le simulateur est constitué des blocs de différents domaines, contenant des modèles fondamentaux des composants du système. Le block de pile à combustible modèle la dynamique d’un système BAHIA® (400 W - 1100 W, 0 A - 70 A nominale) et le block de supercondensateur modèle les cycles charge-décharge d’un module Maxwell de 400 F et 16 V. Un onduleur de tension pont complet avec convertisseur élévateur conditionne l’énergie délivrée par la pile à combustible et un convertisseur bidirectionnel (buck-boost) est connecté au module de supercondensateurs afin de conditionner les cycles de charge-décharge. L’unité des convertisseurs a été dimensionné, puis, un modèle moyen de petits signaux a été formulé afin de décrire la dynamique de ces dispositifs. Les différents composants ont été intégrés dans l’environnement Simulink. Dans une deuxième étape, la stratégie de gestion énergétique a été conçue en considérant les caractéristiques et performances des sources ; le résultat est une stratégie de trois niveaux hiérarchiques, dont l’aspect principal es la définition des lois de commande locales et globale. Dans une troisième étape, le système complet est évalué en termes du niveau d’utilisation des sources, du domaine d’opération de la pile à combustible, et de l’accomplissement des objectifs des commandes locales et global, qui engagent notamment le SOC des supercondensateurs et la régulation de la tension du générateur hybride Energy generation from fossil fuels combustion is predicted to have severe future impacts in the world’s economy and ecology. Fuel cells and supercapacitors are an alternative power source, environmentally friendly.This dissertation presents a regulation architecture developed to coordinate a hybrid renewable source for typical solicitations of electric vehicles in a scaled operating range of 1 kW. The hybrid system is composed of a Polymer Electrolyte Membrane (PEM) fuel cell module, a supercapacitors bank and their respective power conditioning units. In order to optimize the overall operation, the proposed strategy is organized into three hierarchical levels, and the power demand for each energy source is determined in real time with a basis on a frequency distribution and a cutoff frequency, defined in accordance with the dynamical capabilities of the sources.Even if numerous researches have been reported on the subject, few studies have taken into account the proper dynamics of each source in order to optimize the global performance of the hybrid power supply.The goal of this work is to implement a complete simulator integrating not only dynamical models of each energy source, but also dynamical models of the power conditioning units. The control strategy consists of nested loops, arranged in three functional levels of hierarchy. The central idea is to find the optimal set point for each energy source, according to their own physical properties. Contrary to the existing control strategies, this strategy dynamically calculates the appropriate power demand for each energy source. Due to the complexity of the system, cascade control loops are proposed, organized into blocks, according to the system functionality and dynamics.A functional simulation is obtained, where the system ensures the adequate supercapacitor state of charge and soft current demands to keep the fuel cell working in its safe operating region. Thus, lower fuel consumption and rapid response to load demands are guaranteed to improve efficiency.Results demonstrate that the control strategy allows the regulation of the DC bus voltage under UDDS and ECE-15 driving cycles as load profiles. The fuel cell works within its maximum efficiency region, without falling in the degradation zone. In addition, the supercapacitor state of charge remains within the recommended range

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Moraw, Franz Christian. "Hybrid PEM fuel cell : redox cathode approach." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/7720.

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The proton exchange membrane fuel cell (PEMFC) is considered to be a promising power device with a broad range of applications. However, there are still a number of challenges especially concerning performance, cost, and reliability of these systems. The redox flow battery utilizes fundamentally simpler chemistry, but has limitations in terms of membranes/materials used in system construction and in terms of redox regeneration requirements. The hybridization of a PEMFC anode with a redox flow battery cathode, replacing the limiting oxygen electrode, leads to both advantages and compromises in performance. Although there are improvements in kinetics, cell and systems design, and cost, there are restrictions imposed by the regeneration method and membrane contamination. In this work, the Fe³⁺/Fe²⁺ redox fuel cell cathode is characterized over a range of electrolyte concentrations, operating conditions, and electrode materials. A Fe³⁺/Fe²⁺ simulated bio-electrolyte and a simple electrolyte catholyte are studied using CV and ETS to determine kinetic parameters for the electrolyte cathode redox couple, while a prototype single cell fuel cell is used to demonstrate actual fuel cell performance. Electrochemical data shows the effect of ferric ion complexation! polymerization on the operation of both electrolyte systems. The results show that the heterogeneous electron transfer rate constant and diffusion coefficient as well as interface properties all increase with the ratio of total anion species (S0₄²⁻,HS0₄⁻)to ferric species. Fuel cell testing showed no significant difference in performance between the two systems opening up various possibilities for redox species regeneration. Improvements are also achieved through optimization of cathode materials and operating conditions. This hybrid system, part of a strategic NSERC grant (Novel biofuel cell - methane reforming reactor system for electricity generation, #GHGPJ 269967 — 03)(1), showed promising performance even though components such as the membrane were not optimized. Power densities of greater than 0.25 W/cm² were achieved with no platinum group metals on the cathode. In addition, the liquid redox cathode eliminates the need for external humidification and separate cooling for the fuel cell and provides greater design flexibility. Different aspects of the redox cathode were characterized and showed opportunity for further performance improvement.

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Wongkhorsub, Chonlakarn. "Hybrid fuel cell/ejector heat pump system." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422752.

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Yue, Meiling. "Contribution of developing a prognostics-based energy management strategy for fuel cell hybrid system - application to a fuel cell/battery hybrid electric vehicle." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD029.

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Le système de propulsion hybride à pile à combustible (PàC) gagne du terrain sur le marché automobile actuel et offre une solution durable au changement climatique mondial dans le secteur des transports. Cependant, la durabilité et la fiabilité des sources d’énergie utilisées dans le système hybride sont les obstacles inévitables à sa commercialisation massive. Pour optimiser et maximiser la durée de vie du système hybride, une approche de pronostic et gestion de la santé (PHM) est mise en œuvre pour gérer et atténuer le comportement de dégradation des sources d'énergie et appliquée à un véhicule électrique hybride à pile à combustible.Dans ce contexte, deux contributions principales sont apportées. La première consiste à déployer une méthode de pronostic pouvant être utilisée dans le système hybride. Le filtrage de particules, en tant que méthode d'estimation d'état communément utilisée, est adapté aux fins de pronostic dans cette thèse. Il est utilisé pour traiter les données de dégradation imprécises et incertaines et pour estimer la durée de vie utile restante. La méthode est validée par les ensembles de données historiques de PàC et de batterie et les résultats sont évalués par les métriques de pronostic conçues.Ensuite, une deuxième étape sur l’aspect gestion de la santé du PHM est proposée. Comme la répartition de la puissance demandée dans un système hybride est gérée par une stratégie de gestion de l'énergie (EMS), l’orientation de cette étape est de développer une EMS conscient de sa santé dans le contexte du PHM. Une grande quantité de recherches sur les pronostics avec des données expérimentales finies ont été trouvées dans la littérature, alors que la manière d'utiliser les résultats de pronostics pour réaliser des actions de contrôle correctives est rarement discutée. Afin de pallier cette lacune dans les applications de système hybride, un processus de prise de décision basé sur le pronostic est conçu. Les performances sont évaluées en quantifiant la dégradation et la durée de vie du système dans un environnement simulé et une discussion sur l'occurrence des pronostics est lancée pour des investigations ultérieures sur la maintenance Fuel cell hybrid propulsion system is gaining momentum in today's automotive market and offers a sustainable solution for the world climate change in the transport sector. However, the durability and reliability of the power sources used in the hybrid system are the inevitable obstacles for its massive commercialization. To optimize and maximize the lifespan of the hybrid system, a prognostics and health management (PHM) approach is deployed to manage and mitigate the power source degradation behaviour and applied to a fuel cell hybrid electric vehicle.In this context, two main contributions are made. The first stage is to deploy a prognostics method that can be used in the hybrid system. Particle filtering, as a commonly used state estimation method, is adapted for prognostics purpose in this thesis. It is used to handle the imprecise and uncertain degradation data and estimate the remaining useful life. The method is validated by historical fuel cell and battery datasets and the results are evaluated by the designed prognostics metrics.Subsequently, a second stage on the health management aspect of PHM is proposed. As the split of demanded power in a hybrid system is managed by an energy management strategy (EMS), the orientation of this stage is to develop a health-conscious EMS in the context of PHM. A great quantity of researches on prognostics with finished experimental data have been found in the literature, while how to use the prognostics results to make corrective control actions is rarely discussed. To help against this vacancy in hybrid system applications, a prognostics-enabled decision-making process is designed. The performance is evaluated by quantifying the degradation and the lifetime of the system in a simulated environment and a discussion on prognostics occurrence is launched for further investigations on maintenance

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Khazraj, Kaoutar. "Paramétrisation hybride champ/objet et inversion full-wave hybride de données sismiques de puits dans un contexte subsalt." Electronic Thesis or Diss., CY Cergy Paris Université, 2024. http://www.theses.fr/2024CYUN1267.

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Les techniques d'imagerie sismique jouent un rôle crucial dans l'exploration et la compréhension des structures sous la surface de la terre. Dans le domaine de l'exploration pétrolière les zones sous les corps de sel (dites subsalt) représentent un défi pour les techniques d'imagerie conventionnelles. L'application de la full-wave inversion (FWI) aux données sismiques de puits devrait permettre de résoudre au moins partiellement ces difficultés. Dans ce contexte subsalt, l'objectif principal est d'imager et aussi de caractériser les réservoirs d'hydrocarbures pouvant se trouver aux flancs et sous les corps de sel. Néanmoins, le contexte particulier de la sismique de puits, combiné aux défis liés à l'imagerie sous et autour des corps de sel nécessitent l'introduction de contraintes fortes dans le problème inverse géophysique en raison d'une sous-détermination du problème. La présente thèse propose une approche en trois étapes pour aborder ces défis. Tout d'abord, elle suggère d'incorporer de l'information géologique extit{a priori} dans le processus d'inversion en définissant des objets géologiques délimités par des discontinuités permettant aussi une introduction plus fine de l'information ext{a priori} sur les paramètres physiques par objet. Ensuite, elle vise à formaliser et à calculer le gradient par rapport aux paramètres géométriques du modèle qui définissent ces discontinuités. Enfin, elle propose de mettre en place un algorithme d'inversion full-wave hybride qui combine les approches de type champ et de type objet. Cette FWI hybride utilise à la fois le gradient des champs physiques et le gradient relatif aux paramètres géométriques. Le contenu de la thèse est réparti en quatre chapitres. Le premier chapitre présente les concepts fondamentaux utilisés dans l'algorithme FWI hybride. Il met l'accent sur des approches de représentation duale des interfaces (explicite/implicite) par l'utilisation de maillages non-structurés déformables pour la discrétisation des discontinuités et de la méthode level set pour la représentation implicite des objets géologiques dans le problème inverse. Le chapitre 2 décrit les étapes du développement d'une plateforme logicielle permettant l'implémentation numérique de ces approches et la réalisation de tests FWI hybride. Cette plateforme logicielle comprend un code de modélisation de la propagation des ondes par la méthode des éléments spectraux et un code d'inversion basé sur le calcul des gradients simples ou conjugués, avec une approche probabiliste du problème inverse. Le troisième chapitre détaille les différentes étapes de l'algorithme FWI géométrique et sa mise en application à des données de sismique de puits pour estimer la position des interfaces sel/sédiment pour un milieu 2D. Enfin, le quatrième chapitre présente l'algorithme d'inversion hybride et sa mise en oeuvre avec des données de sismique de puits dans le but d'estimer les vitesses des ondes de compression et de cisaillement, ainsi que la position de la frontière des corps de sel pour un milieu 2D. Les résultats des tests numériques présentés sont prometteurs, ce qui permet de valider notre approche d'inversion hybride Seismic imaging techniques play a crucial role in the exploration and understanding of subsurface structures. In the field of petroleum exploration, subsalt zones present a challenge for conventional imaging techniques and full-wave inversion (FWI). The application of FWI to seismic well data is expected to overcome these challenges. The primary goal is to characterize hydrocarbon reservoirs that may be located beneath and alongside salt bodies. However, the context of well seismic imaging, combined with the challenges of imaging beneath and around salt bodies, requires the introduction of strong constraints into the geophysical inverse problem due to its underdetermined nature.This thesis presents a three-step approach to tackle these challenges. Firstly, it suggests incorporating extit{a priori} geological information into the inversion process by defining geological objects bounded by discontinuities. Secondly, it aims to formalize and compute the gradient with respect to the geometric parameters that define these discontinuities. Thirdly, it proposes the implementation of a hybrid full-wave inversion algorithm that combines field and object-based approaches. This hybrid FWI utilizes both the gradient of physical fields and the gradient relative to geometric parameters.The thesis content is divided into four distinct chapters. The first chapter introduces the fundamental concepts used in the hybrid FWI algorithm. It highlights the approach based on a dual representation of interfaces (explicit/implicit) using deformable unstructured meshes for the explicit discretization of discontinuities and the level-set method for the implicit representation of the geological objects in the inverse problem. Chapter 2 describes the development steps of a software platform for the numerical implementation of these approaches and the execution of hybrid FWI tests. This software platform includes a wave propagation modeling code based on the spectral elements method and an inversion code based on the gradient computation using the Green's function method, with a probabilistic approach to the inverse problem. The third chapter outlines the various stages of the geometric FWI algorithm and its application to well seismic data to estimate the position of salt/sediment interfaces in 2D environments. Finally, the fourth chapter presents the hybrid inversion algorithm and its implementation with well seismic data to estimate the velocities of compression and shear waves, as well as the position of salt body boundaries in 2D environments. The results of the presented numerical tests are promising, validating our hybrid inversion approach

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Bath, Andrew. "Performance Characterization of Complex Fuel Port Geometries for Hybrid Rocket Fuel Grains." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1381.

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This research investigated the 3D printing and burning of fuel grains with complex geometry and the development of software capable of modeling and predicting the regression of a cross-section of these complex fuel grains. The software developed did predict the geometry to a fair degree of accuracy, especially when enhanced corner rounding was turned on. The model does have some drawbacks, notably being relatively slow, and does not perfectly predict the regression. If corner rounding is turned off, however, the model does become much faster; although less accurate, this method does still predict a relatively accurate resulting burn geometry, and is fast enough to be used for performance-tuning or genetic algorithms. In addition to the modeling method, preliminary investigations into the burning behavior of fuel grains with a helical flow path were performed. The helix fuel grains have a regression rate of nearly 3 times that of any other fuel grain geometry, primarily due to the enhancement of the friction coefficient between the flow and flow path.

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Strohm, Christian. "Circuit Simulation Including Full-Wave Maxwell's Equations." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22544.

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Diese Arbeit widmet sich der Simulation von elektrischen/elektronischen Schaltungen welche um elektromagnetische Bauelemente erweitert werden. Im Fokus stehen unterschiedliche Kopplungen der Schaltungsgleichungen, modelliert mit der modifizierten Knotenanalyse, und den elektromagnetischen Bauelementen mit deren verfeinerten Modell basierend auf den vollen Maxwell-Gleichungen in der Lorenz-geeichten A-V Formulierung welche durch Finite-Integrations-Technik räumlich diskretisiert werden. Eine numerische Analyse erweitert die topologischen Kriterien für den Index der resultierenden differential-algebraischen Gleichungen, wie sie bereits in anderen Arbeiten mit ähnlichen Feld/Schaltkreis-Kopplungen hergeleitet wurden. Für die Simulation werden sowohl ein monolithischer Ansatz als auch Waveform-Relaxationsmethoden untersucht. Im Mittelpunkt stehen dabei Zeitintegration, Skalierungsmethoden, strukturelle Eigenschaften und ein hybride Ansatz zur Lösung der zugrundeliegenden linearen Gleichungssysteme welcher den Einsatz spezialisierter Löser für die jeweiligen Teilsysteme erlaubt. Da die vollen Maxwell-Gleichungen zusätzliche Ableitungen in der Kopplungsstruktur verursachen, sind bisher existierende Konvergenzaussagen für die Waveform-Relaxation von gekoppelten differential-algebraischen Gleichungen nicht anwendbar und motivieren eine neue Konvergenzanalyse. Auf dieser Analyse aufbauend werden hinreichende topologische Kriterien entwickelt, welche eine Konvergenz von Gauß-Seidel- und Jacobi-artigen Waveform-Relaxationen für die gekoppelten Systeme garantieren. Schließlich werden numerische Benchmarks zur Verfügung gestellt, um die eingeführten Methoden und Theoreme dieser Abhandlung zu unterstützen. This work is devoted to the simulation of electrical/electronic circuits incorporating electromagnetic devices. The focus is on different couplings of the circuit equations, modeled with the modified nodal analysis, and the electromagnetic devices with their refined model based on full-wave Maxwell's equations in Lorenz gauged A-V formulation which are spatially discretized by the finite integration technique. A numerical analysis extends the topological criteria for the index of the resulting differential-algebraic equations, as already derived in other works with similar field/circuit couplings. For the simulation, both a monolithic approach and waveform relaxation methods are investigated. The focus is on time integration, scaling methods, structural properties and a hybrid approach to solve the underlying linear systems of equations with the use of specialized solvers for the respective subsystems. Since the full-Maxwell approach causes additional derivatives in the coupling structure, previously existing convergence statements for the waveform relaxation of coupled differential-algebraic equations are not applicable and motivate a new convergence analysis. Based on this analysis, sufficient topological criteria are developed which guarantee convergence of Gauss-Seidel and Jacobi type waveform relaxation schemes for introduced coupled systems. Finally, numerical benchmarks are provided to support the introduced methods and theorems of this treatise.

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Hashim, Hasan. "Full-spectrum solar energy harvesting using nanotechnology-enabled photovoltaic/thermoelectric hybrid system." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/87143/.

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Carbon emissions, climate change and the finite resource of fossil fuels are driving an increasing need for renewable energy, and in particular, an interest in photovoltaic (PV) cells. Most PV cells operate in temperatures above 25 oC, and the performance of PV cells reduces with increased operation temperature. This research aims to resolve some engineering issues by integrating PV cells with a thermoelectric generator (TEG). Integrating TEG with PV cells helps to transfer heat from the PV through the TEG to an actively or passively cooled heat sink. The temperature difference established across the TEG can generates additional electrical power by the Seebeck effect. The main objective of this research is to investigate the feasibility of developing a PV/TEG hybrid system that can offer better performance than that can be obtained from each individual system. The key parameters, which are crucial to the development of efficient hybrid system, were investigated. These include the temperature coefficient of PV cells, geometry of TEGs and thermal coupling between the PV and TEG. It was found that the dye sensitised solar cells (DSC) has a preferred temperature coefficient that are the most suitable for use in a PV/TEG system. In this work, a theoretical model was also developed for determination of the optimal geometry of the TEG for PV/TEG hybrid systems. A special type of DSCs was designed and fabricated which employ titanium as the counter electrode (other than conventional FTO-glass) to improve the thermal coupling between the PV and TEG. A unique DSC/TEG hybrid system was constructed using this special type of DSC and its generating performance was studied in comparison with a similar system that uses conventional FTO-glass counter electrode. The experimental results show that the power output and efficiency of the hybrid PV/TEG system with Ti counter electrode is significantly higher than the similar system with a conventional FTO-glass electrode due to an improved thermal coupling between the DSC and TEG. It is concluded that a hybrid PV/TEG system can provide improved performance beyond that of each individual system. However, the improvement can only be achieved with appropriate type of PV cells, optimised TEGs and advanced structures for integration, such as Ti counter electrode.

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Ravey, Alexandre. "Conception et gestion de l'énergie des architectures pour véhicules hybrides électriques." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2012. http://tel.archives-ouvertes.fr/tel-00863541.

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Depuis une dizaine d'années, les constructeurs et les grands groupesdu secteur de l'automobile se sont mobilisés autour de la recherche et dudéveloppement de nouveaux prototypes de véhicules économes (moins consommateursd'énergie) et propres (moins de rejets de polluants) tels queles véhicules hybrides et tout électriques. C'est une nouvelle mutation. Ellefait profondément évoluer l'automobile, d'une architecture de propulsionthermique, devenue maîtrisée mais fortement polluante, vers une tractionélectrique ou hybride plus complexe et peu, voire pas du tout, maîtrisée ;le nombre de composants (sources d'énergie, actionneurs, contrôleurs, calculateurs,...) devient important, de nature multidisciplinaire et possédantbeaucoup de non linéarités. De plus, faute de maturité dans ce domaine, àce jour l'industrie de l'automobile ne possède pas encore les connaissancessuffisantes nécessaires à la modélisation, à la simulation et à la conceptionde ces nouveaux véhicules et plus particulièrement les dispositifs relatifs auxsources d'énergie et aux différents actionneurs de propulsion.Les travaux de cette thèse visent à donner des méthodes de conceptiond'une chaine de traction hybride et d'en gérer la gestion de l'énergie. Lathèse s'appuie sur l'exemple de la conception et la gestion de l'énergie d'unvéhicule hybride basé sur une pile à combustible et des batteries.Dans un premier temps, un méthode de dimensionnement des composantsde la chaine de traction est présentée : Elle consiste en l'étude statistique decycle de conduite générés pseudo aléatoirement représentatif de la conduiteen condition réelle de véhicule. Un générateur de cycle de conduite à été créeet est présenté, et la méthode de dimensionnement de la source primaire, iciune pile a combustible, ainsi que le source secondaire de puissance, ici desbatteries, est détaillée. Un exemple est pris pour illustrer cette méthode avecla conception d'un véhicule de type camion poubelle décrivant des cycles deconduites urbains à arrêts fréquents.Dans un second temps, la gestion de l'énergie de la chaine de traction hybridesérie est étudiée : une gestion de l'énergie "offline" est présentée, basé surl'optimisation par programmation dynamique. Cette optimisation permetd'avoir le découpage de la puissance par les deux sources de la chaine detraction de manière optimal pour un cycle précis. De part l'aspect déterministede la programmation dynamique, les résultats servent de référence quant aufuturs développements de gestion temps réel.Un contrôleur temps réel basé sur la logique floue est ainsi exposé et lesrésultats sont comparés par rapport à la gestion "offline". Le contrôleurest ensuite optimisé et rendu adaptatif par un algorithme génétique et unalgorithme de reconnaissance de type de profil routier.Enfin, une introduction à la gestion de l'énergie dans les véhicules hybrides de type : "plug in" est présentée : Elle repose sur le principe de la déterminationde la distance restante à parcourir par la reconnaissance de la destination àl'aide d'une matrice de probabilité de Markov.

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Sivertsson, Martin. "Optimization of Fuel Consumption in a Hybrid Powertrain." Thesis, Linköpings universitet, Fordonssystem, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63563.

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Increased environmental awareness together with new legislative demands on lowered emissions and a rising fuel cost have put focus on increasing the fuel efficiency in new vehicles. Hybridization is a way to increase the efficiency of the powertrain.The Haldex electric Torque Vectoring Device is a rear axle with a built in electric motor, designed to combine all-wheel drive with hybrid functionality. A method is developed for creating a real time control algorithm that minimizes the fuel consumption. First the consumption reduction potential of the system is investigated using Dynamic Programming. A real time control algorithm is then devised that indicates a substantial consumption reduction potential compared to all-wheel drive, under the condition that the assumed and measured efficiencies are accurate. The control algorithm is created using equivalent consumption minimization strategy and is implemented without any knowledge of the future driving mission. Two ways of adapting the control according to the battery state of charge are proposed and investigated. The controller optimizes the torque distribution for the current gear as well as assists the driver by recommending the gear which would give the lowest consumption. The simulations indicate a substantial fuel consumption reduction potential even though the system primarily is an all-wheel drive concept. The results from vehicle tests show that the control system is charge sustaining and the driveability is deemed good by the test-drivers.

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Kerslake, James Anthony. "Fully guided mode studies of hybrid aligned nematics." Thesis, University of Exeter, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426168.

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ABRASSI, ALESSIO. "Fuel cell hybrid systems, dynamics and surge analysis." Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/945503.

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The improvement of energy system performance has led to the development of efficient dynamic compressors able to achieve high compression ratios, high flow rates of fluid and reduced weights. As it normally happens by nature, the higher is the desired performance the more difficult is to achieve it; in the case of dynamic compression, the need to reach increasingly higher compression ratios and larger operational flexibility involves the occurrence of unsteady phenomena such as rotating stall and surge. These two problematic phenomena characterize compressors with violent decrease of performance and severe damage to machines, consequently the topic has been object of several studies over the years. The intensity and behavior of surge are tightly connected to the amount of volumes coupled to the turbo machinery during its operation. For this reason, surge phenomenon is strongly felt in fuel cell gas turbine hybrid system applications, where, primarily the fuel cell, then all the other components (e.g. heat exchangers if present), auxiliaries and connections constitute the vast majority of the volume contained in the system. This work is organized into three macro-chapters, each one is focused on a specific application. The descriptive organization follows the chronological order in which the case studies were addressed and follows the level of maturity of the research object of this program. Therefore, in the following chapters each single case study is presented and discussed separately. The following list anticipates what are the main outcomes and learnings which will be encountered through the text. In this way the candidate wants to clearly summarize what can be considered as primary steps, contribution to the energy systems modeling research field and main outputs of this work: - Mathematical descriptions for components development with integrations and improvements will be described application by application. - Description of the proposed steps followed by the methodologies used to extend compressor maps for surge simulation purposes. A mix of analytical and empirical methods will be suggested through this work. - A method for dynamic delays characterization of complex piping systems named τ-Flow approach have been proposed and applied to these studies. - Parametric studies to investigate the effect of different parameters such as volume size, shaft inertia and equivalent lengths, on the surge cycles characteristics. Impacts of these characteristics will be analyzed in different control configurations where options are applicable. - Simulation results, experimental comparison and validation will be presented at the end of each macro-chapter as completion of the analysis. - The possibility to recover from a surge event acting on by pass valves will be also simulated and presented in the context of Hyper facility analysis.

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Fonseca, Ramon Naiff da. "Optimization of the sizing and the energy management for a hybrid fuel cell vehicle including fuel cell dynamics and durability constraints." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0110/document.

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L'hydrogène à travers de l'utilisation des piles à combustible (PAC), est de plus en plus considéré comme une option énergétique possible au secteur des transports grâce à ces caractéristiques fonctionnelles. Cependant, la technologie liée à la mise en œuvre de véhicules alimentés par une pile à combustible n'a pas encore atteint le niveau de maturité requis. Ainsi, ce travail propose de traiter certaines de ces limitations qui existent encore. Plus précisément, trois thèmes représentent les objectifs de ce travail : Le dimensionnement optimal des éléments présents dans un véhicule hybride à pile à combustible. La gestion d'énergie optimale pour les applications en temps réel et intégrant les contraintes dynamiques du système PAC. Inclusion de la durabilité de la pile à combustible dans la gestion d'énergie du véhicule. Le premier thème est abordé à travers l'élaboration d'une méthodologie de dimensionnement adapté à un véhicule hybride à la pile à combustible. Dans une approche systématique, le dimensionnement proposé combine les exigences de performance présente dans les spécifications techniques du véhicule, les algorithmes d'optimisation, l'analyse de la mobilité de la population et la viabilité économique de la conception. Le deuxième objectif établi a été développé à l'aide d'une approche d'optimisation de la répartition de puissance entre la batterie et le système PAC. Par l'adoption d'une méthode d'optimisation globale combinée à une stratégie de commande prédictive et l'inclusion de la dynamique du système PAC, un algorithme de gestion d'énergie pour des applications de temps réel a été conçu. Enfin, la durabilité de la pile à combustible a été incluse dans ce travail par l'intégration de sa dynamique de dégradation dans le problème d'optimisation lié à la gestion d'énergie. Cette dynamique représente une contrainte à prendre en considération lors de la répartition de puissance entre le système PAC et la batterie The hydrogen, through the use of fuel cell stacks (FC), has been increasily considered as an energy possible option for the transport sector. Nevertheless, the technology related to its implementation in fuel cell vehicles has not reached the required maturity level. Therefore, this work intends to deal some of these existing limitations. More precisely, three topics represent the objectives of this work: The optimal sizing of the element present in the fuel cell hybrid vehicle. The development of an optimal energy management strategy oriented for real time applications and including the dynamic constraints of the FC system. The inclusion of the fuel cell durability in the vehicle energy management strategy. The first topic is tackled by the development of a sizing methodology adapted to the fuel cell hybrid vehicle application. Using a systematic approach, the proposed sizing method combine the performance requirements present in the vehicle's technical specifications, optimization algorithms, population mobility behavior and the economic viability of the design. The second assigned objective was developed using an optimization approach for the power split between the battery and the FC system. Through the adoption of a global optimization method allied with a predictive control strategy and the inclusion of the FC system dynamics, it was created an energy management algorithm oriented for real time applications. Finally, the fuel cell durability was included in this work by the integration of its degradation dynamics in the optimization problem, which is related to the vehicle's energy management. Such dynamic represents a constraint that should be taken into account in the power sharing between the FC system and battery

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39

Brown, Darren. "Simulation and optimization of a fuel cell hybrid vehicle." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 132 p, 2008. http://proquest.umi.com/pqdweb?did=1597632541&sid=11&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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40

Oh, Raymond H. "Processing of a Hybrid Solid Oxide Fuel Cell Platform." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10429.

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Solid oxide fuel cell platforms consisting of alternating cellular layers of yttria-stabilized zirconia electrolyte and Fe-Ni metallic interconnects (Fe45Ni, Fe47.5Ni, Fe50Ni) were produced through the co-extrusion of two particulate pastes. Subsequent thermal treatment in a hydrogen atmosphere was used to reduce iron and nickel oxides and co-sinter the entire structure. Issues surrounding this process include the constrained sintering of the layers and the evolution of residual stress between the dense, fired layers. Sintering curves for individual components of the layers were measured by dilatometry to ascertain each materials impact on overall sintering mismatch. X-ray diffraction, scanning electron microscopy and weight loss were utilized to examine phase evolution within the Fe-Ni alloys during reduction. YSZ powders densified above ~1050C and shrinkage was rapid above the sintering temperature. Shrinkage of the interconnect occurred in two stages: reduction and the initial stages of sintering concluded around ~600C, plateauing shortly and continuing at ~900C as pore removal and grain growth ensued simultaneously. Constrained sintering resulted in the formation of remnant porosity within the interconnect layers. Interconnect compositions were chosen in efforts to minimize disparities in thermal expansion with the electrolyte. Residual strains on the surfaces of the layers were measured by x-ray diffraction. Corresponding stresses were calculated using the sin2y method. Grain growth within the interconnect prohibited random planes to be measured so stress measurements were confined to the ceramic layers. Various material properties such as thermal expansion were collected and employed in a modified finite element model to estimate residual stresses in the platform. A method for determining a crucial parameter, the zero stress temperature was outlined and incorporated. Modeled values were found to agree well with XRD values, providing indirect confirmation of the zero stress temperature calculations. Discrepancies were attributed to microcracks found within the layer that arose due to residual stress values surpassing the tensile strength of the zirconia.

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Bertini, Lorenzo. "Modeling and Optimization of a Fuel Cell Hybrid System." Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-51143.

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The purpose of this project was the modeling, optimization and prediction of a hybrid system composed of a fuel cell, a dc-dc converter and a supercapacitor in series. Lab tests were performed for each device to understand their behavior, and then each one was modeled using software (Simulink). The validation of the model was done by comparing its results with measured data; finally the model was used for the optimization and the prediction of the hybrid system

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Sohn, Munhee 1981. "Hybrid fuel cell for mobile devices : an integrated approach." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35641.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. Includes bibliographical references (p. 90-91). As mobile devices advance to 3G and beyond, there will be a pressing need for increased power to drive these devices, which the current batteries cannot provide. The direct methanol fuel cell has been identified as a promising candidate to provide power to future mobile devices. However, commercialization of mobile devices containing fuel cells has been difficult due to several factors, including inefficiencies in the fuel cell, its large size, and difficulties of integration into the device. An Axiomatic approach was used to identify the key problems that prevent commercialization, along with identifying possible solutions for these problems. These possible solutions were investigated for use in developing a fuel cell for mobile devices of high performance, small size, and integrated hybrid circuitry. To construct a high performance fuel cell, several experiments varying the methanol flow rate, oxygen and methanol concentration, and cathode gas diffusion layer (GDL) were performed on two standard membrane electrode assemblies (MEA). In addition, an MEA was modified using polyvinyl alcohol (PVA) to test its effect on decreasing methanol crossover for improved fuel cell performance. (cont.) In order to decrease the overall size of the fuel cell, a passive fuel cell design was implemented. A potentionstat was used to measure voltage and current and these measurements were used to plot current and power density curves. These results showed that increasing oxygen concentration improved performance, whereas increasing methanol concentration decreased performance due to methanol crossover effects. The effects of the changes of methanol flow rates were negligible and using a plain carbon cloth was just as efficient as using carbon paper coated with a micropourous layer. The performance of the prefabricated MEAs was much lower than that of the experimentally fabricated MEAs, but followed normal performance curve trends. Furthermore, the modified PVA/Nafion membrane showed improvement in preventing methanol crossover although it had decreased proton conductance. Finally, a fuel cell - capacitor hybrid circuit demo was designed and demonstrated. by Munhee Sohn. S.M.

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Park, Yongwan. "Fully Integrated Hybrid Voltage Regulator for Low Voltage Applications." Thesis, State University of New York at Stony Brook, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10132969.

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A novel hybrid regulator topology is proposed to alleviate the weaknesses of existing hybrid topologies. Contrary to the dominant existing practice, a switched-capacitor converter and a resistorless LDO operate in a parallel fashion to supply current and regulate the output voltage. The proposed topology targets a fully integrated regulator without using any inductors and resistors. The primary emphasis is on maximizing power efficiency while maintaining sufficient regulation capability (with ripple voltage less than 10% of the output voltage) and power density. The first implementation of the proposed topology operates in a single frequency mode. Simulation results in 45 nm technology demonstrate a power efficiency of approximately 85% at 100 mA load current with an input and output voltage of, respectively, 1.15 V and 0.5 V. The worst case transient response time is under 20ns when the load current varies from 65 mA to 130 mA. The worst case ripple is 22 mV while achieving a power density of 0.5 W/mm2. This single-frequency hybrid voltage regulator is useful (due to its fast and continuous response and high power efficiency) when the output load current is relatively constant at a certain nominal value. However, the performance is degraded when the load current varies significantly beyond the nominal current since the current provided by switched-capacitor converter is constant. The second implementation of the proposed hybrid regulator topology partially alleviates this issue by employing two different frequencies depending on the load current. This design is also implemented in 45 nm technology. It is demonstrated that the power efficiency is maintained within 60% to 80% even though the load current varies by more than 100 mA. The power density remains the same (0.5 W/mm2). The simulation results of the proposed topology are highly competitive with recent work on integrated voltage regulators.

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Wu, Billy. "Fuel cell hybrid electric vehicle powertrain modelling and testing." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/29949.

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In order to meet the 2050 targets of an 80% reduction in greenhouse gas emissions, electrification of transport is required. Of the zero-emission technologies relating to automotive applications hydrogen fuel cells, lithium-ion batteries and supercapacitors have received the greatest attention. This thesis presents work on the development and implementation of lithium-ion battery, proton exchange membrane fuel cell and supercapacitor models with the aim of developing the tools and techniques required in assessing their feasibility in automotive applications. Experimental validation of each of these devices is provided with insight given into the physical performance limitations of each device. Analysis is then presented on overall powertrain configurations with a focus on the performance of passive hybridisation as a means of reducing the cost of a vehicle powertrain whilst retaining the advantages of hybridisation. Four main chapters of content relating to work on: lithium-ion batteries, proton exchange membrane fuel cell, supercapacitors and vehicle system level analysis is presented with distinct conclusions and novel work presented in each chapter. Lithium-ion batteries The mathematical framework on the development of a psuedo 2D thermally-coupled electrochemical battery model is presented. This was parameterised using a genetic algorithm based technique against pulsed discharge test data for a 4.8 Ah lithium-polymer cell. This physics-based model was used to develop a means of tracking stoichiometric drift of battery electrodes using a simulated slow rate cyclic voltammetry technique as well as the development of a novel differential thermal voltammetry technique for the extraction of the same information as slow rate cyclic voltammetry but at a much faster rate. The differential voltammetry technique was then used to infer stoichiometric drift in a battery. The lithium-ion battery model was also used to investigate the scale up effects from single cell to large automotive scale packs. It was found that interconnect resistances in highly parallel packs can cause significant load inhomogeneities due to the increased overpotential caused by the interconnects which can be on the same order as the battery impedance. Cells near to the pack load points were found to experience the highest loads, with highly transient load conditions amplifying the effect. Proton exchange membrane fuel cells The mathematical framework for the development of a proton exchange membrane fuel cell model which accounted for transient thermal, mass balance and water management effects and the associated balance-of-plant system was presented. This was validated against experimental data from an in-house developed 9.5 kW 75 cell fuel cell system. Inhomogeneities in the reactant delivery, and thus performance of cells, in large automotive stacks were investigated with a focus on localised flooding leading to failure through pin-hole formation. It was shown that low pressure systems suffer from the increased risk of ooding, with location of the cell relative to the inlet/ outlets of the reactants being a critical parameter. Flooding was then shown to lead to catastrophic failure of the fuel cell stack through pin-hole formation which lead to a cascading potential instability and decay due to the bipolar coupling of the cells and anode side hydrogen cross over, respectively.

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Li, Lingling. "Porphyrins, graphitic carbon nitride and their hybrids for photocatalytic solar fuel generation." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/736.

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Photocatalytic solar fuel generation is the most green, sustainable and viable approach to deal with both the ever-growing energy crisis and environmental issues, simultaneously. The work presented in this thesis is focused on the development of new organic carbonaceous semiconductors, typically, carbon quantum dots (CQDs) and graphitic carbon nitride (g-C3N4), and porphyrin small molecules and their hybrids with graphitic carbon nitride, meanwhile, their application in the field of photocatalytic solar fuel generation. In the chapter 1, a general review about background and mechanism of photocatalytic solar fuel generation are introduced first. Next, the features and developments of porphyrin and graphitic carbon nitride for the photocatalytic redox reaction are discussed. In chapter 2, the synthesis, characterization methods and photocatalytic experiment in details are described. In chapter 3, gram-scale CQDs are facilely synthesized by simple thermal treatment of citric acid monohydrate, and microporous 1D nanorods of g-C3N4 are prepared through template-free chemical approach. The photocatalytic properties of 1D protonated g-C3N4 (HCN) modified with different amount of CQDs were evaluated by the rate of H2- evolution under visible light irritation. The results demonstrate that g-C3N4/CQDs with the optimal CQDs amount of 0.25 wt.% afford the highest H2-production rate of 382 μmol h-1 g-1 with apparent quantum yield (AQY) of 1.9% which was about 3-fold of pure g- C3N4. The composite g-C3N4/CQDs show a remarkable stability against the photocorrosion within a continuous experiment period over 12h. The enhanced photocatalytic H2-production activity could be attribute to the intimate interface between CQDs and g-C3N4, which not only significantly improves the visible-light absorption, but also prolongs the lifetime of charge carriers and suppresses the recombination of photogenerated electron-hole pairs. This work showed that low-cost and metal-free CQDs could be an efficient photosensitizer to promote photocatalytic hydrogen generation. In chapter 4, we reported a new array of push-pull isomeric naphthalimide- porphyrins (ZnT(p-NI)PP) to investigate the effect of naphthalimide and molecular constitution on light driven hydrogen evolution from water splitting. These compounds were synthesized by integration of four naphthalimide moieties on meso-substituion of porphyrin macrocycle through para phenyl linker. Porphyrins were characterized by UV- Vis, Fluorescence and DFT calculations and compared with those of zinc tertapheylporphyrin (ZnTPP). When these porphyrins were employed as photocatalyst for the photocatalytic hydrogen production (PHP) with platinum co-catalyst, they delivered high hydrogen efficiency compared to that of ZnTPP. Particularly, ZnT(p-NI)PP exhibited 203 times higher hydrogen efficiency than the ZnTPP. This could be ascribed to the efficient exciton dissociation into holes and electrons at the photoexcited state of ZnT(p-NI)PP and then electrons were transferred to the proton through platinum. These results indicate that introduction of naphthalimide at meso-position of porphyrin through para phenyl linker is a versatile strategy to improve the photocatalytic hydrogen evolution of porphyrin based materials. In addition, the other two isomeric naphthalimide conjugated porphyrins through meta-and ortho-phenyl linker, ZnT(m-NI)PP and ZnT(o-NI)PP are also developed for photocatalytic H2 production. The para-linked isomer, ZnT(p-NI)PP delivered a much higher H2 production rate of 973 μmol h−1g -1 compared to that of ZnT(m-NI)PP (597 μmol h−1g −1) and ZnT(o-NI)PP (54 μmol h−1g −1), respectively. This could be attributed to the efficient intramolecular energy transfer from the naphthalimide to the porphyrin ring. In chapter 5, a series of NP/g-C3N4 hybrids of graphitic carbon nitride (g-C3N4) with naphthalimide-porphyrin (ZnT(p-NI)PP, labelled as NP) have been developed for photocatalytic hydrogen production. Planar naphthalimide-porphyrins are adsorbed onto flexible two-dimensional g-C3N4 through π-π stacking, which are characterized by scanning electronic microscopy and X-ray photoelectron spectroscopy. Except for its function as photosensitizer, NP in the hybrids could efficient inhibit the charge recombination by electron transfer for the lower lowest unoccupied molecular orbital of NP than g-C3N4, whereas facilitate energy transfer from g-C3N4 donor to NP acceptor for efficient overlap of emission spectrum of NP and absorption of g-C3N4. As a result, the hybrid containing weigh ratio of 2% NP (2%NP/g-C3N4) exhibits an enhanced photocatalytic hydrogen production rate (HPR) of 2297 μmol g−1 h −1, while pristine g- C3N4 shows a HPR of 698 μmol g−1 h −1. The 2%NP/g-C3N4 shows the best performance when compared with the reported hybrids of g-C3N4 with Zn(II) -tetrakis(4- carboxylphenyl) porphyrin (ZnTCPP/g-C3N4) and Zn(II)-tetrakis(4- hydroxyphenyl)porphyrin (ZnTHPP/g-C3N4) in photocatalytic hydrogen production under the same conditions. In the chapter 6, the future work on photocatalytic CO2 reduction, perspectives and conclusions are included

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Merkley, Stephen L. "Effects of Radiation Heating on Additively Printed Hybrid Fuel Grain Oxidizer-to-fuel Ratio Shift." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5230.

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This thesis examined the hypothesis that radiative heat transfer in small-scale printed-fuel hybrid rocket motors is responsible for the observed decreasing oxidizer-to-fuel (O/F) ratio shift. The magnitude of the radiation term was negligible for the motor sizes and types of propellants that have been previously tested, but was reintroduced in this study. To prove this hypothesis, a detailed enthalpy balance model was developed and tested using experimental fuel regression rate data obtained from a variety of motor scales using additively-manufactured acrylonitrile butadiene styrene (ABS) fuel grains.

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Ardianti, Retno. "The psychological well-being of hybrid entrepreneurs: Longitudinal comparative studies of hybrid entrepreneurs, full time self employed and the paid employed." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/207088/1/Retno_Ardianti_Thesis.pdf.

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The phenomenon of hybrid entrepreneurship where individuals work in paid and self-employment simultaneously is prevalent. However, the psychological well-being implication of working in this unique work configuration is not yet studied. By using data from Indonesia and the United Kingdom, this thesis explains and demonstrates certain differences of hybrid entrepreneurs’ psychological well-being patterns that distinguish them from their full-time paid and self-employed counterparts. In doing so, this thesis contributes to the literature of entrepreneurship and well-being by building the theoretical insight into the link between hybrid entrepreneurship and well-being, as well as providing empirical evidence from two different country settings.

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Yang, Zhuo. "Investigation of the excitonic properties of hybrid and fully inorganic perovskite using magneto-spectroscopy." Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0004/document.

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Au cours des dernières années, les perovskites hybrides organiques-inorganiques ont été employées en tant qu’absorbeurs de lumière, en raison de leurres excellentes propriétés optiques et électroniques. L’efficacité de conversion des photons des cellules solaires hybrides à base de perovskites a augmenté de 6,9% à 23,6% au cours des dernières années. Le but de cette thèse est d’étudier les propriétés optiques et électroniques des perovskites à l’aide de spectroscopie magnéto-optique. Nous avons étudié la relation entre les propriétés excitoniques et la microstructure des perovskites hybrides. Nous avons effectué des mesures de magnéto-transmission sur des couches minces polycristallines de MAPbI3 et des mesures de magnéto-réflectivité sur un monocristal de MAPbI3. Nous avons monté que, à basse température, l’énergie de liaison de l’exciton et sa masse réduite sont les mêmes pour tous les échantillons de MAPbI3 indépendamment de la taille des cristaux.Ensuite, nous avons étudié les propriétés électroniques des perovskites entièrement inorganiques, à savoir les composés CsPbX3 (X = I ou Br ou un mélange de ceux-ci). En effectuant des mesures de magnéto-transmission sur CsPbX3, nous avons déterminé les énergies de liaison de l’exciton et la masse réduite avec une grande précision. Une comparaison des valeurs de constante diélectrique des perovskites inorganiques et inorganiques montre que, à basse température lorsque les mouvements des cations organiques sont interdits, la contribution dominante à l’écrantage diélectrique estliée au mouvement relatif dans la cage à base de halogénures de plomb Optical and electronic properties. The photon conversion efficiency of hybrid perovskite based solar cells has increased from 6.9% to 23.6% within the last few years. The aim of this thesis is to investigate the optical and electronic properties of perovskite materials using magneto-optical techniques. We have investigated the relationship between the excitonic properties and the microstructure of hybrid perovskites. We have performed magneto-transmission measurement on MAPbI3 polycrystalline thin films and magneto-reflectivity measurement on a MAPbI3 single crystal. We find that, at low temperature, the exciton binding energy and reduced mass are the same for all MAPbI3 samples with a variety of crystal grain sizes.We have also investigated the electronic properties of the fully inorganic perovskites, namely CsPbX3 compounds (X = I or Br or a mixture of those). By performing the magneto-transmission measurement on CsPbX3, we have determined the exciton binding energies and reduced mass with high accuracy. A comparison of the values of dielectric constant for the fully inorganic and the hybrid organic-inorganic perovskites indicates that, at low temperature when the organic cations are frozen, the dominant contribution to the dielectric screening is related to the relative motion within the lead halide cage

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Zhang, Xiaodong, and 张晓东. "Design and implementation of auxiliary energy systems for hybrid electric vehicles." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46596641.

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50

Greenwell, Wesley D. "Real-time power management of a fuel cell/ultracapacitor hybrid." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219848515/.

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