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1
Rosenqvist, Lisa. "Energy Transfer and Conversion in the Magnetosphere-Ionosphere System". Doctoral thesis, Uppsala University, Department of Astronomy and Space Physics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8716.
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Magnetized planets, such as Earth, are strongly influenced by the solar wind. The Sun is very dynamic, releasing varying amounts of energy, resulting in a fluctuating energy and momentum exchange between the solar wind and planetary magnetospheres. The efficiency of this coupling is thought to be controlled by magnetic reconnection occurring at the boundary between solar wind and planetary magnetic fields. One of the main tasks in space physics research is to increase the understanding of this coupling between the Sun and other solar system bodies. Perhaps the most important aspect regards the transfer of energy from the solar wind to the terrestrial magnetosphere as this is the main source for driving plasma processes in the magnetosphere-ionosphere system. This may also have a direct practical influence on our life here on Earth as it is responsible for Space Weather effects. In this thesis I investigate both the global scale of the varying solar-terrestrial coupling and local phenomena in more detail. I use mainly the European Space Agency Cluster mission which provide unprecedented three-dimensional observations via its formation of four identical spacecraft. The Cluster data are complimented with observations from a broad range of instruments both onboard spacecraft and from groundbased magnetometers and radars.
A period of very strong solar driving in late October 2003 is investigated. We show that some of the strongest substorms in the history of magnetic recordings were triggered by pressure pulses impacting a quasi-stable magnetosphere. We make for the first time direct estimates of the local energy flow into the magnetotail using Cluster measurements. Observational estimates suggest a good energy balance between the magnetosphere-ionosphere system while empirical proxies seem to suffer from over/under estimations during such extreme conditions.
Another period of extreme interplanetary conditions give rise to accelerated flows along the magnetopause which could account for an enhanced energy coupling between the solar wind and the magnetosphere. We discuss whether such conditions could explain the simultaneous observation of a large auroral spiral across the polar cap.
Contrary to extreme conditions the energy conversion across the dayside magnetopause has been estimated during an extended period of steady interplanetary conditions. A new method to determine the rate at which reconnection occurs is described that utilizes the magnitude of the local energy conversion from Cluster. The observations show a varying reconnection rate which support the previous interpretation that reconnection is continuous but its rate is modulated.
Finally, we compare local energy estimates from Cluster with a global magnetohydrodynamic simulation. The results show that the observations are reliably reproduced by the model and may be used to validate and scale global magnetohydrodynamic models.
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Ziemann, Dirk. "Theory of Excitation Energy Transfer in Nanohybrid Systems". Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/22142.
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Im Folgenden werden Transferprozesse in Nanohybridsystemen theoretisch untersucht.
Diese Hybridsysteme sind vielversprechende Kandidaten für neue optoelektronische Anwendungen und erfahren daher ein erhebliches Forschungsinteresse.
Jedoch beschränken sich Arbeiten darüber hauptsächlich auf experimentelle Untersuchungen und kaum auf die dazugehörige theoretische Beschreibung.
Bei den theoretischen Betrachtungen treten entscheidende Limitierungen auf.
Es werden entweder Details auf der atomaren Ebene vernachlässigt oder Systemgrößen betrachtet, die wesentlich kleiner als im Experiment sind.
Diese Thesis zeigt, wie die bestehenden Theorien verbessert werden können und erweitert die bisherigen Untersuchungen durch die Betrachtung von vier neuen hoch relevanten Nanohybridsystemen.
Das erste System ist eine Nanostruktur, die aus einem Au-Kern und einer CdS-Schale besteht.
Beim zweiten System wurde eine ZnO/Para-Sexiphenyl Nanogrenzfläche untersucht.
Die zwei anderen Systeme beinhalten jeweils einen CdSe-Nanokristall, der entweder mit einem Pheophorbide-a-Molekül oder mit einem röhrenförmigen Farbstoffaggregat wechselwirkt.
In allen Systemen ist der Anregungsenergie-Transfer ein entscheidender Transfermechanismus und steht im Fokus dieser Arbeit.
Die betrachteten Hybridsysteme bestehen aus zehntausenden Atomen und machen daher eine individuelle Berechnung der einzelnen Subsysteme sowie deren gegenseitiger Wechselwirkung notwendig.
Die Halbleiter-Nanostrukturen werden mit der Tight-Binding-Methode und der Methode der Konfigurationswechselwirkung beschrieben.
Für das molekulare System wird die Dichtefunktionaltheorie verwendet.
Die dazugehörigen Rechnungen wurden von T. Plehn ausgeführt.
Das metallische Nanoteilchen wird durch quantisierte Plasmon-Moden beschrieben.
Die verwendeten Theorien ermöglichen eine Berechnung von Anregungsenergietransfer in Nanohybridsystemen von bisher nicht gekannter Systemgröße und Detailgrad.In the following, transfer phenomena in nanohybrid systems are investigated theoretically. Such hybrid systems are promising candidates for novel optoelectronic devices and have attracted considerable interest. Despite a vast amount of experimental studies, only a small number of theoretical investigations exist so far. Furthermore, most of the theoretical work shows substantial limitations by either neglecting the atomistic details of the structure or drastically reducing the system size far below the typical device extension. The present thesis shows how existing theories can be improved. This thesis also expands previous theoretical investigations by developing models for four new and highly relevant nanohybrid systems. The first system is a spherical nanostructure consisting of an Au core and a CdS shell. By contrast, the second system resembles a finite nanointerface built up by a ZnO nanocrystal and a para-sexiphenyl aggregate. For the last two systems, a CdSe nanocrystal couples either to a pheophorbide-a molecule or to a tubular dye aggregate. In all of these systems, excitation energy transfer is an essential transfer mechanism and is, therefore, in the focus of this work. The considered hybrid systems consist of tens of thousands of atoms and, consequently, require an individual modeling of the constituents and their mutual coupling. For each material class, suitable methods are applied. The modeling of semiconductor nanocrystals is done by the tight-binding method, combined with a configuration interaction scheme. For the simulation of the molecular systems, the density functional theory is applied. T. Plehn performed the corresponding calculations. For the metal nanoparticle, a model based on quantized plasmon modes is utilized. As a consequence of these theories, excitation energy transfer calculations in hybrid systems are possible with unprecedented system size and complexity.
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Garay, Rosas Ludwin. "System Simulation of Thermal Energy Storage involved Energy Transfer model in Utilizing Waste heat in District Heating system Application". Thesis, KTH, Kraft- och värmeteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161726.
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Nowadays continuous increase of energy consumption increases the importance of replacing fossil fuels with renewable energy sources so the CO2 emissions can be reduced. To use the energy in a more efficient way is also favorable for this purpose. Thermal Energy Storage (TES) is a technology that can make use of waste heat, which means that it can help energy systems to reduce the CO2 emissions and improve the overall efficiency. In this technology an appropriate material is chosen to store the thermal energy so it can be stored for later use. The energy can be stored as sensible heat and latent heat. To achieve a high energy storage density it is convenient to use latent heat based TES. The materials used in this kind of storage system are called Phase Change Materials (PCM) and it is its ability of absorbing and releasing thermal energy during the phase change process that becomes very useful. In this thesis a simulation model for a system of thermal energy transportation has been developed. The background comes from district heating systems ability of using surplus heat from industrials and large scale power plants. The idea is to implement transportation of heat by trucks closer to the demand instead of distributing heat through very long pipes. The heat is then charged into containers that are integrated with PCM and heat exchangers. A mathematical model has been created in Matlab to simulate the system dynamics of the logistics of the thermal energy transport system. The model considers three main parameters: percentage content of PCM in the containers, annual heat demand and transport distance. How the system is affected when these three parameters varies is important to visualize. The simulation model is very useful for investigation of the economic and environmental capability of the proposed thermal energy transportation system. Simulations for different scenarios show some expected results. But there are also some findings that are more interesting, for instance how the variation of content of PCM gives irregular variation of how many truck the system requires, and its impact on the economic aspect. Results also show that cost for transporting the heat per unit of thermal energy can be much high for a small demands compared to larger demands.
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Tran, Thu-Trang. "Electron and multielectron reaction characterizations in molecular photosystems by laser flash photolysis, towards energy production by artificial photosynthesis". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS320.
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La demande énergétique de l’humanité augmente rapidement et ne montre aucun signe de ralentissement. Parallèlement à cette problématique, l'utilisation abusive de combustibles fossiles est l'une des principales causes d'augmentation de la concentration de CO₂ dans l'atmosphère. Ces problèmes doivent être résolus en termes de limitation des émissions de CO₂ et de recherche de sources d'énergie renouvelables pour remplacer les combustibles fossiles. De nos jours, l’énergie solaire est l’une des sources d’énergie renouvelables les plus efficaces. La conversion de l'énergie de la lumière solaire en électricité dans le photovoltaïque ou en énergie chimique par le biais de processus photocatalytiques implique invariablement un transfert d'énergie photo-induit et un transfert d'électrons. Dans ce contexte, l'objectif de la thèse est d'étudier les processus photo-induits dans les photosystèmes moléculaires utilisant la photolyse par flash laser. Le premier thème de cette thèse porte sur l’étude du transfert monoélectronique dans des systèmes de dyades donneur-accepteur en vue d’optimiser l’efficacité de la séparation des charges et de son application dans la cellule solaire organique photovoltaïque. Le deuxième thème de cette thèse porte sur l’étude de deux systèmes modèles de photosynthèse artificielle étudiés pour la possibilité d’une accumulation de charge par étapes. Ensuite, différents systèmes photocatalytiques, développés pour la photoréduction du CO₂, ont été étudiés. La compréhension des processus photo-induits devraient permettre l’amélioration de l'efficacité de la réduction du CO₂ dans les systèmes photocatalytiques pratiquesThe energy demand of humanity is increasing rapidly, and shows no signs of slowing. Alongside this issue, abuse using fossil fuels is one of the main reasons which leads to an increase in atmospheric CO₂ concentration. These problems have to be solved in terms of both limiting CO₂ emission and finding renewable energy sources to replace fossil fuels. Nowadays, solar energy appears as one of the most effective renewable energy sources. Conversion of solar light energy to electricity in photovoltaics or to chemical energy through photocatalytic processes invariably involves photoinduced energy transfer and electron transfer. In this context, the aim of the thesis focuses on studying photoinduced processes in molecular photosystems using laser flash photolysis. The first theme of this thesis focus on studying single electron transfer in Donor-Acceptor Dyad systems towards optimization efficiency of charge separation and application in the photovoltaic organic solar cell. In the second theme of this thesis, two model systems of artificial photosynthesis were investigated to assess the possibility of stepwise charge accumulation on model molecules. A fairly good global yield of approximately 9% for the two charge accumulation on MV²⁺ molecule was achieved. Then, different photocatalytic systems, which have developed for CO₂ reduction, were studied. Understanding of the photoinduced processes is an important step toward improving the efficiency of reduction of CO₂ in practical photocatalytic systems
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Johansson, Robert. "Investigation of the Turbulent Flow and Heat Transfer around a Heated Cube Cooled by Multiple Impinging jets in a Cross-Flow". Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21851.
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The fast development in electronics has resulted in faster and faster computers. Furthermore, the electronic components trend to get smaller and smaller by the year. With more processing power combined with smaller components the heat generation rapidly increases. The scope of this study is to examine a spot cooling technique consisting with different geometry of multiple impinging jets in combination with a cross-flow by the use of CFD. The case is limited to a heated wall mounted cube cooled by a impinging jet as well as an multiple impinging jets in a low velocity cross-flow. This study can be divided into two parts a verification study and a detailed study. The verification study consist of comparison between RSM model and measured values for both the turbulent flow and the surface temperature. The single impinging mesh consists of 934 k elements while the plus 1439 k and cross consists of 2809 k elements. All the meshes are created in ANSYS fluent and this paper contains a detailed guide to create them. The verification study proved that RSM can predict the complicated flow with good agreement with the single impinging jet. The heat transfer coefficient differ substantially between the cases. The PIV compared to the UDF for the inlet velocity profiles had a 21\% increase in heat transfer coefficient in the top layer of the cube. In all the simulations the cross had at least an increase of 18\% on average \(h\). While there was no real verification study for the multiple impinging jets I would still argue that cross is better than the plus sign geometry in terms of heat transfer.
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Schaible, Uwe. "An integrated high speed flywheel energy storage system for peak power transfer in electric vehicles /". *McMaster only, 1997.
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Wu, Weiwei. "Energy transfer in hybrid system consisting of quantum dots/quantum wells and small luminescent molecules". HKBU Institutional Repository, 2009. http://repository.hkbu.edu.hk/etd_ra/1067.
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Schaible, Uwe. "An integrated high-speed flywheel energy storage system for peak power transfer in electric vehicles". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ42763.pdf.
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Gills, Zelda Y. "Dynamical control of irregular intensity fluctuations in a chaotic multimode solid state laser system". Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/29859.
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Muchmore, Suzi. "Knowledge transfer : a qualitative investigation of the UK low carbon innovation system". Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/35118.
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Innovation programmes require organisations to transfer both technology and knowledge to the diverse actors who operate within innovation eco-systems. The changing relationship between science and society has witnessed the growth of public private partnerships (PPP) to create new knowledge, while also triggering the emergence of a new role for universities as catalysts for innovation. This brings many challenges, stemming from the inherent nature of knowledge and the complex interactions involved with inter-disciplinary knowledge transfer. Concurrently, these public-funded programmes come under increasing scrutiny to demonstrate greater societal and economic impact as a return on research investment. Knowledge generated within the UK low carbon energy innovation system has the potential to facilitate the achievement of national emission targets. However, while knowledge may be successfully created, there is no guarantee that it will be disseminated and utilised in a way that contributes to the achievement of knowledge-related objectives. Current literature concentrates on the micro level inhibitors and enablers of knowledge transfer; however, a gap in empirical work which investigates system level knowledge interactions is evident. Research and practical application in this field has historically centred on technology transfer whilst under-emphasising the crucial role of knowledge within this complex, socio-technical innovation system. The overall aim of this qualitative study is to achieve a better understanding of the influences of knowledge transfer across a defined innovation system. This is achieved through the perceptions of participants via two case studies; one in a PPP and one in a University. Semi-structured interviews were conducted with twenty-eight participants, along with document analysis and participant observation at workshops, to investigate the participant perceptions. A three tier (macro-, meso- and micro-level) data analysis approach was adopted to reflect the systems level interactions. The study found that knowledge transfer is often perceived as the dissemination of information via explicit forms of knowledge, which may or may not be used by stakeholders to achieve innovation objectives. The main barriers to stakeholders utilising knowledge included: accessibility to knowledge; fit-for-purpose knowledge; stakeholder motivation/ability to use the knowledge; and viewing knowledge as an object. While there is an emerging impact agenda in academia, cultural and normative influences direct researchers towards traditional academic outputs (e.g. publications). Knowledge utilisation by stakeholders was found to be maximised through relational, stakeholder driven models, which view knowledge as a process. Knowledge utilisation was context specific, and, due to complex system influences, was never guaranteed to occur. Although planning for knowledge utilisation was undertaken at both the PPP and the University, implementing and measuring results was found to be difficult due to dynamic system influences such as understanding stakeholder motivations, resourcing constraints and complexity in the desired project outcomes. This makes adaptability and responsiveness important qualities for knowledge producers, while also necessitating specific skill sets. Based on this work, a set of principles were developed which should guide more effective utilisation of knowledge and promote more impactful research outcomes.
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Gobeze, Habtom Berhane. "Ultrafast Photoinduced Energy and Electron Transfer Studies in Closely Bound Molecular and Nanocarbon Donor-Acceptor Systems". Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248516/.
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As part of the study, photosynthetic system constructs based on BF2-chelated dipyrromethene (BODIPY), BF2-chelated azadipyrromethene (AzaBODIPY), porphyrin, phthalocyanine, oxasmaragdyrin, polythiophene, fullerene (C60), single-walled carbon nanotube and graphene are investigated. Antenna systems of BODIPY dyads and oligomers having BODIPY as an excitation energy donor connected to different acceptors including BODIPY, azaBODIPY, oxasmaragdyrin and aluminum porphyrin are studied. Different synthetic methodologies are used to afford donor-acceptor systems either directly linked with no spacer or with short spacers of varying length and orientation. The effect of donor orientation, donor optical gap as well as nature of donor-acceptor coupling on the donor-acceptor spectral overlap and hence the rate of excitation energy transfer is investigated. In all these systems, an ultrafast energy transfer followed by electron transfer is observed. In particular, in a directly connected BODIPY-azaBODIPY dyad an unusually ultrafast energy transfer (~ 150−200 f) via Förster mechanism is observed. The observation of energy transfer via Förster instead of Dexter mechanism in such closely coupled donor-acceptor systems shows the balance between spatial and electronic coupling achieved in the donor-acceptor system.
Moreover, in donor-acceptor systems involving semiconducting 1D and 2D materials, covalently functionalized single-walled carbon nanotubes via charge stabilizing (TPA)3ZnP and noncovalently hybridized exfoliated graphene via polythiophene chromophores are studied for their charge transportation functions. In both cases, not only an ultrafast charge transfer in the range of (~ 2−5 p) is observed but also the charge-separated states were long lived implying the potential of these functionalized materials as efficient charge transporting substrates with organic chromophores for photovoltaic and optoelectronic applications where ultrafast intercomponent charge transfer is vital. In addition, as a final part of this dissertation, the mechanisms of electron injection and back electron transfer in heterogeneous systems involving supramolecularly anchored high potential chromophores on TiO2 film are studied by femtosecond transient absorption spectroscopy. In this study, not only are important insights gained on the utilization of supramolecular anchoring of chromophores such as porphyrins, phthalocyanines, and their perflorinated high potential analogues, chromophores currently showing promise as highly efficient sensitizers in dye sensitized solar cells, on TiO2 film but also on the effect of anchor length and sensitizer orientation on the rates of electron injection and back electron transfer at the sensitizer-TiO2 interface.
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Malatkar, Pramod. "Nonlinear Vibrations of Cantilever Beams and Plates". Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/28301.
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A study of the nonlinear vibrations of metallic cantilever beams and plates subjected to transverse harmonic excitations is presented. Both experimental and theoretical results are presented. The primary focus is however on the transfer of energy between widely spaced modes via modulation. This phenomenon is studied both in the presence and absence of a one-to-one internal resonance. Reduced-order models using Galerkin discretization are also developed to predict experimentally observed motions. A good qualitative agreement is obtained between the experimental and numerical results.
Experimentally the energy transfer between widely spaced modes is found to be a function of the closeness of the modulation frequency to the natural frequency of the first mode. The modulation frequency, which depends on various parameters like the amplitude and frequency of excitation, damping factors, etc., has to be near the natural frequency of the low-frequency mode for significant transfer of energy from the directly excited high-frequency mode to the low-frequency mode.
An experimental parametric identification technique is developed for estimating the linear and nonlinear damping coefficients and effective nonlinearity of a metallic cantilever beam. This method is applicable to any single-degree-of-freedom nonlinear system with weak cubic geometric and inertia nonlinearities. In addition, two methods, based on the elimination theory of polynomials, are proposed for determining both the critical forcing amplitude as well as the jump frequencies in the case of single-degree-of-freedom nonlinear systems.
An experimental study of the response of a rectangular, aluminum cantilever plate to transverse harmonic excitations is also conducted. Various nonlinear dynamic phenomena, like two-to-one and three-to-one internal resonances, external combination resonance, energy transfer between widely spaced modes via modulation, period-doubled motions, and chaos, are demonstrated using a single plate. It is again shown that the closeness of the modulation frequency to the natural frequency of the first mode dictates the energy transfer between widely spaced modes.Ph. D.
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Morisson, Vincent. "Heat transfer modelling within graphite/salt composites : from the pore scale equations to the energy storage system". Bordeaux 1, 2008. http://www.theses.fr/2008BOR13581.
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Ce travail de thèse s'inscrit dans le cadre du projet européen DISTOR dont le but est de concevoir des systèmes de stockage d'énergie adaptés aux centrales solaires utilisant la technologie DSG (génération de vapeur direct). Les matériaux à changement de phase élaborés sur la base d'une matrice de graphite dont les pores sont remplis de sel, ont été identifiés comme étant les meilleurs candidats tant en terme de stockage, qu'en terme de coût et d'adaptation aux paramètres de fonctionnement de notre centrale solaire. L'objectif de ce travail a été d'étudier le comportement thermique de ce matériau composite à 3 échelles ; à l'échelle du pore, de l'échantillon et du système de stockage. Il a pu ainsi être démontré que les transferts thermiques au sein d'un matériau graphique/sel peuvent être représentés à l'échelle macroscopique par l'intermédiaire d'un modèle Enthalpie Température standard avec des propriétés thermiques équivalentes et des fonctions enthalpie température correspondant à une fusion étalée plutôt que localisée. Une méthode permettant la caractérisation complète des composites Graphite/Sel a été proposée à travers un seul échantillon et une seule expérience. Enfin un outil pour la conception préliminaire et l'analyse du système de stockage a été développé. Les avantages d'utiliser les MCP développés dans le cadre du projet DISTOR ont ainsi pu être mis en avant.
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Mitchell, Amanda. "Development of a Novel Genetically Encoded FRET System Using the Unnatural Amino Acid Anap". Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:107177.
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Thesis advisor: Abhishek ChatterjeeFörster Resonance Energy Transfer (FRET) offers a powerful approach to study biomolecular dynamics in vitro as well as in vivo. The ability to apply FRET imaging to proteins in living cells provides an excellent tool to monitor important dynamic events such as protein conformational changes, protein-protein interactions, and proteolysis reactions. However, selectively incorporating two distinct fluorophores into the target protein(s) that are capable of FRET interaction within the complex cellular milieu is challenging. Consequently, terminal fusion to genetically encoded fluorescent proteins has emerged as the predominant labeling strategy for FRET studies in vivo. However, a major limitation of this strategy stems from the large size of the fluorescent proteins, which may perturb the native properties of the target, and restricted attachment only to the termini of the target. We reasoned that using genetically encoded fluorescent unnatural amino acids would overcome several of these challenges associated with currently available labeling strategies owing to their small size and the ability to introduce them site- specifically and co-translationally. Here, we report the use of the fluorescent unnatural amino acid “Anap” as a FRET donor with green and yellow fluorescent protein acceptors. We demonstrate the utility of this labeling strategy using proteolysis and conformational change models, and step towards in vivo studies by further developing a proteolysis system in cell lysates
Thesis (MS) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Papastergiou, Konstantinos. "A power converter with a rotating secondary stage for an airborne radar system". Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/1984.
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Contact-less transfer of energy has always been a desired feature for systems that require reliable and durable power transfer across their moving parts. In rotary equipment in particular, slip-rings are the established solution with off-the-shelf and customised solutions readily available in the market. Despite the mature technology, slip-rings suffer wear and are prone to arcing, making frequent maintenance a necessity. In this project a rotating transformer is proposed as an alternative solution for contact-less transfer of energy across the revolving frame of an airborne electronic-scanning radar. This thesis is based on the hypothesis that the Phase-Shifted Full Bridge (PSFB) topology can efectively utilise the parasitic components of the rotating transformer to achieve efficient (over 90%) power conversion at the kW range. The first part of this work concentrates on the study of the magnetic interface and its electrical properties. Initially the magnetic structure of the transformer is studied in order to gain understanding of the effects of the physical layout of the component to its electrical behaviour. The problems of low magnetising and increased leakage inductance are quantified by measurements, calculations and finite element analysis. An accurate electrical model is built and used to calculate the transformer voltage and current gain. The second part of the research programme aims at the compilation of a design strategy for a PSFB incorporating a rotating transformer. An algorithm is presented, that optimises the magnetic component structure in order to achieve minimum switching losses and spread the conduction losses between the transformer and power switches. The last stage involves the evaluation of the design algorithm through prototyping and testing. Some topological variations are tested and compared with the original conventional PSFB converter. The thesis concludes with a discussion of the results and future challenges.
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Crosby, Kevin C. "Macromolecular Organization and Cell Function: A Multi-System Analysis". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/30259.
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The interior of the cell is a densely crowded and complex arena, full of a vast and diverse array of molecules and macromolecules. A fundamental understanding of cellular physiology will depend not only upon a reductionist analysis of the chemistry, structure, and function of individual components and subsystems, but also on a sagacious exegesis of the dynamic and emergent properties that characterize the higher-level system of living cells. Here, we present work on two aspects of the supramolecular organization of the cell: the controlled assembly of the mitotic spindle during cell division and the regulation of cellular metabolism through the formation of multienzyme complexes.
During division, the cell undergoes a profound morphological and molecular reorganization that includes the creation of the mitotic spindle, a process that must be highly controlled in order to ensure that accurate segregation of hereditary material. Chapter 2 describes results that implicate the kinase, Zeste-white3/Shaggy (Zw3/Sgg), as having a role in regulating spindle morphology.
The congregation of metabolic enzymes into macromolecular complexes is a key feature of cellular physiology. Given the apparent pervasiveness of these assemblies, it seems likely that some of the mechanisms involved in their organization and regulation might be conserved across a range of biosynthetic pathways in diverse organisms. The Winkel laboratory makes use of the flavonoid biosynthetic pathway in Arabidopsis as an experimental model for studying the architecture, dynamics, and functional roles of metabolic complexes. Over the past several years, we have accumulated substantive and compelling evidence indicating that a number of these enzymes directly interact, perhaps as part of a dynamic globular complex involving multiple points of contact between proteins. Chapter 3 describes the functional analysis of a predicted flavonol synthase gene family in Arabidopsis. The first evidence for the interaction of flavonoid enzymes in living cells, using fluorescent lifetime imaging microscopy fluorescent resonance energy transfer analysis (FLIM-FRET), is presented in Chapter 4.Ph. D.
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Guliyev, Ruslan. "Rational Design Of Ratiometric Chemosensor Via Modulation Of Energy Donor Efficiency". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609889/index.pdf.
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Rational design of fluorescent chemosensors is an active area of supramolecular chemistry, photochemistry and photophysics. Ratiometric chemosensors are even more important, as they have an internal system for selfcalibration.
In order to develop a new methodology for a ratiometric chemosensor design, we proposed coupling of energy transfer phenomenon to ion sensing.
In this study, we targeted energy transfer cassette type chemosensors, where the efficiency of transfer is modulated on the donor side, by metal ion binding which changes the spectral overlap. This work involves the synthesis of a number of EET systems with varying degrees of EET efficiency.
The results suggest that this strategy for ratiometric ion sensing is a promising one, enabling a modular approach in chemosensor design.
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Escamilla, Garcia Pablo Emilio. "Evaluation and proposed development of the municipal solid waste management system in Mexico City". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/evaluation-and-proposed-development-of-the-municipal-solid-waste-management-system-in-mexico-city(3ae730a7-b8c3-4cb9-a990-f4cca372be6e).html.
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The work reported involves the evaluation of technologies and management systems applied to Municipal Solid Waste (MSW). The study focuses on Mexico City, which with a population of approximately 9 million inhabitants and an estimated daily generation of 13,000 tonnes of waste, is encountering extreme waste management issues. The structures and public policies designed to provide waste management services have proved inadequate in relation to high rates of population growth and intensive business activities. The significant increase in demand has led the government of Mexico City to base public services on rudimentary techniques using obsolete equipment. The research approaches the problem through the analysis of several different aspects: (1) a comprehensive literature review of waste management including technologies and legal frameworks; (2) a general overview of the main demographic, geographic and economic aspects of Mexico City; (3) an extensive analysis of historic and future waste generation profiles and composition of waste in Mexico City; (4) an evaluation of the current status of the waste management system, including programmes, plans, facilities and infrastructure; and (5) a comparative study of the waste management system of Mexico City and the systems of selected international cities. The evaluation resulted in the identification of the following significant issues: (1) limitations in legislation related to waste management and environmental laws; (2) high population growth and increasing business activity, which contribute escalating generation of MSW; (3) ineffective public policies focused on waste management; (4) significant gaps in low levels of recycling activities; (5) obsolescence of equipment, infrastructure and facilities; (6) lack of diversification in treatment methods for MSW; and (7) failure to exploit market opportunities in the waste management sector. In addition to the evaluation of the system in Mexico City, the analysis of waste management systems in selected international cities allowed the author to identify key factors in order to develop integrated proposals. The analysis highlighted significant aspects including: legal frameworks, the participation of the private sector, waste hierarchy, and guiding principles for plans and programmes. The information enabled the design of a proposed development plan of a comprehensive waste management system in Mexico City through two main proposals. Firstly, an integrated programme for waste management in Mexico City was developed to provide feasible long-term strategies in the field of waste management. The specific objectives, goals, actions, responsibilities and time scales were defined in order to provide concrete activities under specific fields of operation. Secondly, a project to obtain funding for technology transfer structured according to technical, market and economic studies, was elaborated. The guide is aimed to exemplify an investment project through the analysis of a feasibility study related to generation of energy from biogas in a controlled landfill in Mexico City. The process may be adapted to the acquisition of technology in different sectors of the waste management process.
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Gondre, Damien. "Numerical modeling and analysis of heat and mass transfers in an adsorption heat storage tank : Influences of material properties, operating conditions and system design on storage performances". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI022/document.
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Le développement de solutions de stockage de l'énergie est un défi majeur pour permettre la transition énergétique d'un mix énergétique fortement carboné vers une part plus importante des énergies renouvelables. La nécessité de stocker de l'énergie vient de la dissociation, spatiale et temporelle, entre la source et la demande d'énergie. Stocker de l'énergie répond à deux besoins principaux : disposer d'énergie à l'endroit et au moment où on en a besoin. La consommation de chaleur à basse température (pour le chauffage des logements et des bureaux) représente une part importante de la consommation totale d'énergie (environ 35 % en France en 2010). Le développement de solutions de stockage de chaleur est donc d'une grande importance, d'autant plus avec la montée en puissance des énergies renouvelables. Parmi les technologies de stockage envisageables, le stockage par adsorption semble être le meilleur compromis en termes de densité de stockage et de maintient des performances sur plusieurs cycles de charge-décharge. Cette thèse se focalise donc sur le stockage de chaleur par adsorption, et traite de l'amélioration des performances du stockage et de l'intégration du système au bâtiment. L'approche développée pour répondre à ces questions est numérique. L'influence des propriétés thermophysiques de l'adsorbant et du fluide sur la densité de puissance d'une part, mais aussi sur la densité de stockage et l'autonomie du système, est étudiée. L'analyse des résultats permet de sélectionner les propriétés des matériaux les plus influentes et de mieux comprendre les transferts de chaleur et de masse au sein du réacteur. L'influence des conditions opératoires est aussi mise en avant. Enfin, il est montré que la capacité de stockage est linéairement dépendante du volume de matériau, tandis que la puissance dépend de la surface de section et que l'autonomie dépend de la longueur du lit d'adsorbant. Par ailleurs, le rapport entre l'énergie absorbée (charge) et relâchée (décharge) est d'environ 70 %. Mais pendant la phase de charge, environ 60 % de la chaleur entrant dans le réacteur n'est pas absorbée et est directement relâchée à la sortie. La conversion globale entre l'énergie récupérable et l'énergie fournie n'est donc que de 25 %. Cela montre qu'un système de stockage de chaleur par adsorption ne peut pas être pensé comme un système autonome mais doit être intégré aux autres systèmes de chauffage du bâtiment et aux lois de commande qui les régissent. Utiliser la ressource solaire pour le préchauffage du réacteur est une idée intéressante car elle améliore l’efficacité de la charge et permet une réutilisation de la part récupérée en sortie pour le chauffage direct du bâtiment. La part stockée sous forme sensible peut être récupérée plusieurs heures plus tard. Le système est ainsi transformé en un stockage combiné sensible/adsorption, avec une solution pour du stockage à long terme et pour du stockage à court termeThe development of energy storage solutions is a key challenge to enable the energy transition from fossil resources to renewable energies. The need to store energy actually comes from a dissociation between energy sources and energy demand. Storing energy meets two principal expectations: have energy available where and when it is required. Low temperature heat, for dwellings and offices heating, represents a high share of overall energy consumption (i.e. about 35 %). The development of heat storage solutions is then of great importance for energy management, especially in the context of the growing part of renewable energies. Adsorption heat storage appears to be the best trade off among available storage technologies in terms of heat storage density and performances over several cycles. Then, this PhD thesis focuses on adsorption heat storage and addresses the enhancement of storage performances and system integration. The approach developed to address these issues is numerical. Then, a model of an adsorption heat storage tank is developed, and validated using experimental data. The influence of material thermophysical properties on output power but also on storage density and system autonomy is investigated. This analysis enables a selection of particularly influencing material properties and a better understanding of heat and mass transfers. The influence of operating conditions is also underlined. It shows the importance of inlet humidity on both storage capacity and outlet power and the great influence of discharge flowrate on outlet power. Finally, it is shown heat storage capacity depends on the storage tank volume, while outlet power depends on cross section area and system autonomy on bed length. Besides, the conversion efficiency from absorbed energy (charge) to released energy (discharge) is 70 %. But during the charging process, about 60 % of incoming heat is not absorbed by the material and directly released. The overall conversion efficiency from energy provided to energy released is as low as 25 %. This demonstrates that an adsorption heat storage system cannot be thought of as a self-standing component but must be integrated into the building systems and control strategy. A clever use of heat losses for heating applications (in winter) or inlet fluid preheating (in summer) enhances global performances. Using available solar heat for system preheating is an interesting option since a part is instantly retrieved at the outlet of the storage tank and can be used for direct heating. Another part is stored as sensible heat and can be retrieved a few hours later. At least, it has the advantage of turning the adsorption storage tank into a combined sensible-adsorption storage tank that offers short-term and long-term storage solutions. Then, it may differ avoidable discharges of the sorption potential and increase the overall autonomy (or coverage fraction), in addition to optimizing chances of partial system recharge
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Deshpande, Dhananjay D. "Computer Modeling Of A Solar Thermal System For Space Heating". Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1484142894264319.
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Björk, Erik. "Energy Efficiency Improvements in Household Refrigeration Cooling Systems". Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93061.
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This thesis is based on eight articles all related to the characteristics of the cooling system and plate evaporator of a household refrigerator. Through these articles, knowledge is provided that can be used to increase the operational efficiency in household refrigeration. Papers A, B and C focus on heat transfer and pressure drop in a commonly used free convection evaporator – the plate evaporator. Applicable correlations are suggested on how to estimate the air side heat transfer, the refrigerant side pressure drop and the refrigerant side heat transfer. Papers D, E and F hold a unique experimental study of the refrigerant charge distribution in the cooling system at transient and steady state conditions. From this cyclic losses are identified and estimated and ways to overcome them are suggested. In paper G the topic “charging and throttling” is investigated in an unparalleled experimental study based on more than 600 data points at different quantities of charge and expansions device capacities. It results in recommendations on how to optimize the capillary tube length and the quantity of refrigerant charge. Finally, Paper H holds a thermographic study of the overall cooling system operating at transient conditions. Overall, a potential to lower the energy use by as much as 25 % was identified in the refrigerator studied. About 10 % was found on the evaporator’s air side. 1-2 % was identified as losses related to the edge effect of the evaporator plate. About 8 % was estimated to be cyclic losses. About 5 % was found in cycle length optimization. It is believed that most of these findings are of general interest for the whole field of household refrigeration even though the results come from one type of refrigerator. Suggestions of simple means to reduce the losses without increasing the unit price are provided within the thesisQC 20120411
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Lim, Timothy M. "A MODULAR ELECTRICAL POWER SYSTEM ARCHITECTURE FOR SMALL SPACECRAFT". UKnowledge, 2016. http://uknowledge.uky.edu/ece_etds/90.
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Small satellites and CubeSats have established themselves within the aerospace community because of their low cost and high return on investment. Many CubeSats are developed in a short time frame and often leverage commercial off the shelf components for quick turnaround missions. With regard to the Electrical Power System, commercially available products typically use a centralized architecture. However, a centralized architecture is not reusable, since missions that require additional solar arrays or batteries would necessitate a redesign of the power system. With the range of CubeSat sizes and mission goals, it is obvious that a one-size-fits-all solution is not appropriate. This thesis details a reusable and scalable power system architecture applicable to a variety of missions. Reusability is achieved by using common building blocks or "modules," where the same modules can be used between missions. Scalability is achieved by not limiting the number of modules that can be connected together—more modules can be added as needed. In this system, solar arrays and battery units connect directly to a common bus, supplying an unregulated voltage to each subsystem. These subsystems then regulate the bus voltage to their individual needs. The power system also features direct energy transfer and solar-only operation.
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Vishwanath, Indushri Vikas. "Development of a Catalytic System for Air-to-Liquid Mass Transfer Mechanism". Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1479135783395588.
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Heebl, Jason Daniel. "Development and Characterization of a Tunable Resonant Shielded Loop Wireless Non-Radiative Power Transfer System". University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1304426560.
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Ellis, Benjamin. "Moderation of high-energy fast neutrons in beryllium from a tokamak fusion reactor and heat transfer to the cooling water system". Master's thesis, Faculty of Engineering and the Built Environment, 2020. http://hdl.handle.net/11427/32607.
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A modeling demonstration of the moderation of 14.1 MeV primary neutrons in beryllium emitted from a D-T fusion nuclear reaction. The energy deposited from neutron-beryllium interactions which produces heat in the blanket of a fusion tokamak. A review of literature and data available for neutron-beryllium interactions is provided to support the MC software of a simplified model of the ITER first wall and blanket. Energy deposited in regions of the model using FLUKA are used to calculate a polynomial heat flux profile through the model. One dimensional conductive heat transfer through the model is performed and the cooling capacity of the coolant channels via convective heat transfer is explored.
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Venkatesan, Balaji Srinivasan. "Modeling, Simulation and Correlation of Drag losses in a Power Transfer Unit of an All- Wheel Drive System". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-283800.
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A Power Transfer Unit (PTU) of an All-Wheel Drive System is a hypoid gear transmission unit that distributes the power from the vehicle transmission to all wheels of the vehicle. This thesis aims at increasing the fidelity of the analytical power loss calculation methods through test data correlation and develop a 1D simulation model that can be used to evaluate the drag losses in the PTU at early design stages. Firstly, the analytical methods to predict the frictional losses and oil churning losses due to the hypoid gearset, rolling bearings and seals immersed in oil are studied. Several drag loss tests with different combinations of internal components, bearing preloads and with/without the presence of oil were previously conducted on the PTU at different speeds and temperatures at zero torque. The power losses are computed in ROMAX Energy and Excel using different analytical methods available in the literature for each component in the PTU. Then the results from the drag loss tests are segregated component-wise for data correlation with the losses evaluated previously. Based on the data correlation, modification factors are introduced for all analytical methods to match the segregated test results. The demand in the automotive industry to reduce time to market is high. Hence, system-level simulation was chosen as a solution to assess the system efficiency at early concept design stage, saving a lot of time and aid the detailed design. 1D simulation technique is used to study the total power loss of the PTU to optimize its design. The thesis is aimed at developing a 1D system model of the PTU in a commercial tool called LMS AMESim, to evaluate the total power loss of the unit. Inbuilt component models from the software library are used to build a sketch of a simplified lumped mass model of the physical system. The model is simulated in a time domain temporal analysis. The total power loss results simulated using AMESim are compared to the efficiency tests results conducted at different torque levels and ROMAX results. Comparisons between the simulations and test data shows that the system model is accurate and can be used in predicting the power losses in the PTU in the early design stages. This model can also be used to study the influential factors through sensitivity analysis of different parameters which can be done as an extension to the current scope of this work.En kraftöverföringsenhet (PTU) i ett fyrhjulsdriftsystem är en hypoidväxellådsöverföringsenhet som fördelar kraften från växellådan till alla hjul i fordonet. Det rapporterade arbetet syftar till att öka konfidensen i de analytiska beräkningsmetoderna för effektförlust genom testdatakorrelation och genom att utveckla en 1D-simuleringsmodell som kan användas för att utvärdera dragförlusterna i PTUn i tidiga designfaser. För det första studeras analysmetoderna för att förutsäga friktionsförluster och plaskförluster på grund av hypoidväxeln, rullager och tätningar nedsänkta i olja. Flera ”Drag Loss”-tester med olika kombinationer av interna komponenter, lagerförspänningar och med / utan närvaro av olja utfördes tidigare på PTU vid olika hastigheter och temperaturer utan pålagt moment. Effektförlusterna beräknas i ROMAX Energy med olika analysmetoder tillgängliga i litteraturen för varje komponent i PTU. Sedan separeras resultaten från dragförlusttesterna komponentmässigt för datakorrelation med de tidigare utvärderade förlusterna. Baserat på datakorrelationen införs modifieringsfaktorer för alla analysmetoder för att matcha de segregerade testresultaten. Efterfrågan inom fordonsindustrin att minska tiden till marknaden är hög. Därför väljs simulering på systemnivå som en lösning för att bedöma systemeffektiviteten i ett tidigt konceptdesignfas, vilket sparar mycket tid och underlättar den detaljerade designen. 1D-simuleringsteknik används för att studera PTUns totala effektförlust för att optimera dess design. Arbetet syftar till att utveckla en 1D-systemmodell av PTU i ett kommersiellt verktyg som heter LMS AMESim, för att utvärdera enhetens totala effektförlust. Inbyggda komponentmodeller från programvarubiblioteket används för att skapa en skiss av en förenklad modell av det fysiska systemet. De totala effektförlusterna beräknade med AMESim jämförs med effektivitetstestresultaten vid olika vridmomentnivåer och ROMAX-resultat. Från korrelationen med testresultaten observeras att systemmodellen är korrekt och kan användas för att förutsäga effektförlusterna i PTU i de tidiga designstadierna. Denna modell kan också användas för att studera de viktigaste faktorerna genom känslighetsanalys av olika parametrar, vilket kan göras som en förlängning av detta arbete.
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Chan, Teck-Wai. "Proximity-to-Separation Based Energy Function Control Strategy for Power System Stability". Queensland University of Technology, 2003. http://eprints.qut.edu.au/15840/.
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The issue of angle instability has been widely discussed in the power engineering literature. Many control techniques have been proposed to provide the complementary synchronizing and damping torques through generators and/or network connected power apparatus such as FACTs, braking resistors and DC links. The synchronizing torque component keeps all generators in synchronism while damping torque reduces oscillations and returns the power system to its pre-fault operating condition. One of the main factors limiting the transfer capacity of the electrical transmission network is the separation of the power system at weak links which can be understood by analogy with a large spring-mass system. However, this weak-links related problem is not dealt with in existing control designs because it is non-trivial during transient period to determine credible weak links in a large power system which may consist of hundreds of strong and weak links. The difficulty of identifying weak links has limited the performance of existing controls when it comes to the synchronization of generators and damping of oscillations. Such circumstances also restrict the operation of power systems close to its transient stability limits. These considerations have led to the primary research question in this thesis, "To what extent can the synchronization of generators and damping of oscillations be maximized to fully extend the transient stability limits of power systems and to improve the transfer capacity of the network?" With the recent advances in power electronics technology, the extension of transfer capacity is becoming more readily achievable. Complementary to the use of power electronics technology to improve transfer capacity, this research develops an improved control strategy by examining the dynamics of the modes of separation associated with the strong and weak links of the reduced transmission network. The theoretical framework of the control strategy is based on Energy Decomposition and Unstable Equilibrium Points. This thesis recognizes that under extreme loadings of the transmission network containing strong and weak links, weak-links are most likely to dictate the transient stability limits of the power system. We conclude that in order to fully extend the transient stability limits of power system while maximizing the value of control resources, it is crucial for the control strategy to aim its control effort at the energy component that is most likely to cause a separation. The improvement in the synchronization amongst generators remains the most important step in the improvement of the transfer capacity of the power system network.
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Li, Ke. "Analysis of Energy losses of Microbial Fuel Cells (MFCs) and Design of an Innovative Constructed Wetlands-MFC". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500604673955179.
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Kabzáni, Matej. "Vplyv energetických opatrní na ceny prevádzky budovy". Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318594.
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The theme of the diploma thesis "Effect of energy care on building prices" is the design and assessment of several measures, two of which generally lead to lower heating costs. The diploma thesis deals with evaluation of the current state of the family house and determination of PENB before the construction modifications and subsequently after the construction modifications, defining subsequent measures for energy saving implementation, both in terms of energy, economic and also environmental.
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Arnoux, Gillean. "Novel Insights into Mass and Energy Transfer and Mid-Ocean Ridges from Seismic Imaging of the East Pacific Rise and Juan de Fuca Ridge". Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24532.
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In this dissertation, I use seismic imaging and waveform modeling methods to investigate melt migration processes and the structure of the magma plumbing system beneath the East Pacific Rise (EPR) and Endeavour segment of the Juan de Fuca Ridge, respectively. This work begins by studying shallow mantle reflections beneath the EPR. I find the amplitude versus offset and waveform characteristics of the reflections to be consistent with a sub-horizontal dunite channels located up to 20 km off-axis. The depth of the dunite channels correlate with patterns of mantle melt delivery and the predicted base of the thermal lithosphere, suggesting the channels are thermally controlled and may have formed in situ via dissolution by focused flow at the base of the lithosphere. This interpretation is consistent with field observations in ophiolites and numerical modeling of melt-focusing channels. The three-dimensional velocity structure of the Endeavour segment is then investigated to identify how patterns of mantle melt delivery influence the segment-scale distribution of crustal melt and crustal accretion. The results from this study indicate that the mantle magmatic system is skewed relative to the ridge-tracking crustal magmatic system and that this skew exerts primary control on magmatic, tectonic, and hydrothermal activity at the Endeavour segment. In regions where mantle melt delivery is axis-centered, mantle-derived melts are efficiently transported from the mantle to the crust, resulting in frequent crustal melt replenishment, associated seismogenic cracking, and enhanced crustal melt content that drives vigorous hydrothermal activity. Conversely, sites of off-axis melt delivery are characterized by less efficient vertical melt transport, resulting in infrequent crustal melt injection and hence, reduced crustal melt content and hydrothermal activity. Next, I focus on how along-axis variations in magma replenishment modulate crustal permeability and the intensity of hydrothermal circulation. Using full-waveform inversion, I show that sites of localized magma replenishment to the axial magma lens, along with induced seismogenic cracking, coincide with enhanced permeability. I conclude that the frequency of magma injection governs hydrothermal circulation patterns and heat flux at mid-ocean ridges.
This dissertation includes previously published and unpublished coauthored material.
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Raymond, Alexander William. "Investigation of microparticle to system level phenomena in thermally activated adsorption heat pumps". Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34682.
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Heat actuated adsorption heat pumps offer the opportunity to improve overall energy efficiency in waste heat applications by eliminating shaft work requirements accompanying vapor compression cycles. The coefficient of performance (COP) in adsorption heat pumps is generally low. The objective of this thesis is to model the adsorption system to gain critical insight into how its performance can be improved. Because adsorption heat pumps are intermittent devices, which induce cooling by adsorbing refrigerant in a sorption bed heat/mass exchanger, transient models must be used to predict performance. In this thesis, such models are developed at the adsorbent particle level, heat/mass exchanger component level and system level.
Adsorption heat pump modeling is a coupled heat and mass transfer problem. Intra-particle mass transfer resistance and sorption bed heat transfer resistance are shown to be significant, but for very fine particle sizes, inter-particle resistance may also be important. The diameter of the adsorbent particle in a packed bed is optimized to balance inter- and intra-particle resistances and improve sorption rate. In the literature, the linear driving force (LDF) approximation for intra-particle mass transfer is commonly used in place of the Fickian diffusion equation to reduce computation time; however, it is shown that the error in uptake prediction associated with the LDF depends on the working pair, half-cycle time, adsorbent particle radius, and operating temperatures at hand.
Different methods for enhancing sorption bed heat/mass transfer have been proposed in the literature including the use of binders, adsorbent compacting, and complex extended surface geometries. To maintain high reliability, the simple, robust annular-finned-tube geometry with packed adsorbent is specified in this work. The effects of tube diameter, fin pitch and fin height on thermal conductance, metal/adsorbent mass ratio and COP are studied. As one might expect, many closely spaced fins, or high fin density, yields high thermal conductance; however, it is found that the increased inert metal mass associated with the high fin density diminishes COP. It is also found that thin adsorbent layers with low effective conduction resistance lead to high thermal conductance. As adsorbent layer thickness decreases, the relative importance of tube-side convective resistance rises, so mini-channel sized tubes are used. After selecting the proper tube geometry, an overall thermal conductance is calculated for use in a lumped-parameter sorption bed simulation. To evaluate the accuracy of the lumped-parameter approach, a distributed parameter sorption bed simulation is developed for comparison. Using the finite difference method, the distributed parameter model is used to track temperature and refrigerant distributions in the finned tube and adsorbent layer. The distributed-parameter tube model is shown to be in agreement with the lumped-parameter model, thus independently verifying the overall UA calculation and the lumped-parameter sorption bed model.
After evaluating the accuracy of the lumped-parameter model, it is used to develop a system-level heat pump simulation. This simulation is used to investigate a non-recuperative two-bed heat pump containing activated carbon fiber-ethanol and silica gel-water working pairs. The two-bed configuration is investigated because it yields a desirable compromise between the number of components (heat exchangers, pumps, valves, etc.) and steady cooling rate. For non-recuperative two-bed adsorption heat pumps, the average COP prediction in the literature is 0.39 for experiments and 0.44 for models. It is important to improve the COP in mobile waste heat applications because without high COP, the available waste heat during startup or idle may be insufficient to deliver the desired cooling duty. In this thesis, a COP of 0.53 is predicted for the non-recuperative, silica gel-water chiller. If thermal energy recovery is incorporated into the cycle, a COP as high as 0.64 is predicted for a 90, 35 and 7.0°C source, ambient and average evaporator temperature, respectively. The improvement in COP over heat pumps appearing in the literature is attributed to the adsorbent particle size optimization and careful selection of sorption bed heat exchanger geometry.
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Moberg, Simon. "Artificial photosynthesis - 4-Aminobenzoic acids effect on charge transfer in a photo catalytic system". Thesis, Uppsala universitet, Materialteori, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-390835.
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Artificial photosynthesis is used to harvest solar energy and store it in the form of chemical bonds. The system of interest in this study does this by splitting water into hydrogen and oxygen gas through a plasmon assisted process, collective oscillations from free electron gas. This is a renewable way to store energy that could be used as an alternative to fossil based fuel. In this study, a small part of this photo catalytic system is studied, namely the interaction between plasmonically active silver nanoparticles (Ag NPs) transferring photo-excited electrons via a linker molecule, 4-aminobenzoic acid (pABA). The pABA linker molecule transfers charge from the Ag surface to a semiconductor and a catalyst performing the water splitting. The pABA can bind in different ways onto the Ag-surface and the aim of this study is to examine which bond is strongest and which best enables charge transfer. To this purpose three systems where simulated quantum mechanically using a supercomputer. The total free energy of the systems was computed and compared. Out of the three studied binding sites, the hollow-site bond (pABA binding to three silver atoms) was found to have the lowest energy, meaningit's the strongest of the possible bonds. Additionally it was found that the band gap (the energy needed to transfer charge) for the pABA decreased when bound to the Ag-surface. The hollow-site bound pABA also had the smallest band gap, meaning it requires the least energy to transfer a charge and should therefore be the best bond fitted for the photo catalytic system.Artificiell fotosyntes används för att absorbera solenergi och förvara den i formen av kemiska bindningar. Systemet som används i denna studie gör detta genom att splittra vatten till vätgas och syrgas genom en plasmon assisterad process. Detta är ett förnyelsebart sätt att förvara energi och kan användas som ett alternativ till fossila bränslen. I denna studie studeras en liten del utav detta fotokatalytiska system nämligen interaktionen där plasmonaktiva silvernanopartiklar (Ag NPs) överför foto-exciterade elektroner genom molekyllänken 4-aminobensoesyra (pABA). Molekyllänken pABA överför laddning från silverytan till en halvledare och en katalys som utför splittringen av vattnet. pABA kan binda på olika sätt tillen silveryta och denna studie syftar till att undersöka vilken utav bindningarna som är starkast och vilken som effektivast överför laddning. För att göra detta simulerades tre system kvantmekaniskt med hjälp av en superdator, ett system för varje sorts bindning. Den totala fria energin av systemen beräknades och jämfördes. Av de tre undersökta bindningarna hadehollow-site bindningen (pABA som binder till tre silveratomer) längst energi, vilket betyder att det är den starkaste av bindningarna. Utöver detta så visade det sig att bandgapet (energin som krävs för att överföra laddning) minskade för pABA när den var bunden till Ag-ytan. Hollow-site bundet pABA hade även minst bandgap, vilket betyder att den kräver minst energi för att överföra laddning och är därmed den mest effektiva bindningen för det fotokatalytiska systemet.
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Miller, Daniel Jeffrey. "Design and Analysis of an Innovative Semi-Flexible Hybrid Personal-Body-Armor System". Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3247.
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Current military-grade rifle body armor technology uses hard ballistic plates positioned on top of flexible materials, such as woven Kevlar® to stop projectiles and absorb the energy of the impact. However, absorbing the impact energy and stopping a rifle projectile comes at a cost to the wearer - mobility. In this thesis, a new concept for personal body armor is proposed - a semi-flexible hybrid body armor. This hybrid armor is comprised of two components that work as a system to effectively balance the flexibility offered by a soft fabric based armor with the protection level of hard plated armor. This work demonstrates techniques used to analyze and design the hybrid armor to be compliant with National Institute of Justice guidelines. In doing so, finite element analysis is used to simulate the effect of a projectile impacting the armor at various locations, angles, and velocities, while design of experiments is used to study the effect of these various impact combinations on the ability of the armor component(s) (including the wearer) to absorb energy.
The flexibility and protection offered by the two component armor system is achieved by the use of proven technique and innovative geometry. For the analytical design, the material properties, contact area(s), dwell duration, and energy absorption are all carefully considered. This yields a lightweight but yet effective armor, which is estimated to weigh 36% less than the current military grade hard body armor.
Using ANSYS, several simulations were conducted using finite element analysis, including a direct center impact, along with various other impacts to investigate possible weak points in the armor. In doing so, it is determined that only one of these impact locations is indeed a potential weak point. The finite element analysis continues to show that a rifle projectile impacting at an oblique angle reduces the energy transferred to the wearer by about 25% (compared to a direct impact).
A design of experiments approach was used to determine the influence of various input parameters, such as projectile impact velocity and impact location. It is shown that the projectile impact velocity contributes 36% to the ability of the wearer to absorb energy, whereas impact velocity contributes only 13% to the energy absorbed by the top armor component. Furthermore, the analysis shows that the impact location is a highly influential factor (with a 69% contribution) in the energy absorption by the top armor component.
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Butt, Nathaniel J. "Development and Thermal Management of a Dynamically Efficient, Transient High Energy Pulse System Model". Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1527602141695356.
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Mohamed, Ahmed A. S. Mr. "Bidirectional Electric Vehicles Service Integration in Smart Power Grid with Renewable Energy Resources". FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3529.
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As electric vehicles (EVs) become more popular, the utility companies are forced to increase power generations in the grid. However, these EVs are capable of providing power to the grid to deliver different grid ancillary services in a concept known as vehicle-to-grid (V2G) and grid-to-vehicle (G2V), in which the EV can serve as a load or source at the same time. These services can provide more benefits when they are integrated with Photovoltaic (PV) generation. The proper modeling, design and control for the power conversion systems that provide the optimum integration among the EVs, PV generations and grid are investigated in this thesis.
The coupling between the PV generation and integration bus is accomplished through a unidirectional converter. Precise dynamic and small-signal models for the grid-connected PV power system are developed and utilized to predict the system’s performance during the different operating conditions. An advanced intelligent maximum power point tracker based on fuzzy logic control is developed and designed using a mix between the analytical model and genetic algorithm optimization.
The EV is connected to the integration bus through a bidirectional inductive wireless power transfer system (BIWPTS), which allows the EV to be charged and discharged wirelessly during the long-term parking, transient stops and movement. Accurate analytical and physics-based models for the BIWPTS are developed and utilized to forecast its performance, and novel practical limitations for the active and reactive power-flow during G2V and V2G operations are stated. A comparative and assessment analysis for the different compensation topologies in the symmetrical BIWPTS was performed based on analytical, simulation and experimental data. Also, a magnetic design optimization for the double-D power pad based on finite-element analysis is achieved. The nonlinearities in the BIWPTS due to the magnetic material and the high-frequency components are investigated rely on a physics-based co-simulation platform. Also, a novel two-layer predictive power-flow controller that manages the bidirectional power-flow between the EV and grid is developed, implemented and tested. In addition, the feasibility of deploying the quasi-dynamic wireless power transfer technology on the road to charge the EV during the transient stops at the traffic signals is proven.
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Jun, Hyoung Yoll. "Development of a fuel-powered compact SMA (Shape Memory Alloy) actuator system". Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/1426.
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The work presents investigations into the development of a fuel-powered compact SMA actuator system. For the final SMA actuator, the K-alloy SMA strip (0.9 mm x 2.5 mm), actuated by a forced convection heat transfer mechanism, was embedded in a rectangular channel. In this channel, a rectangular piston, with a slot to accommodate the SMA strip, ran along the strip and was utilized to prevent mixing between the hot and the cold fluid in order to increase the energy density of the system. The fuel, such as propane, was utilized as main energy source in order to achieve high energy and power densities of the SMA actuator system. Numerical analysis was carried out to determine optimal channel geometry and to estimate maximum available force, strain and actuation frequency. Multi-channel combustor/heat exchanger and micro-tube heat exchanger were designed and tested to achieve high heat transfer rate and high compactness. The final SMA actuator system was composed of pumps, valves, bellows, multi-channel combustor/heat exchanger, micro-tube heat exchanger and control unit. The experimental tests of the final system resulted in 250 N force with 2 mm displacement and 1.0 Hz actuation frequency in closed-loop operation, in which the hot and the cold fluid were re-circulated by pumps.
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Bruno, Aina. "The transfer of knowledge for renewable energy policy-making between Europe and Peru in the period 2006-2009 : Impacts in the Peruvian Solar Photovoltaic innovation system". Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-228866.
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Energy generation and use is one of the main contributors to climate change, as it is responsible for two thirds of the global greenhouse gas emissions (IEA 2015). In this context, renewable energies (RE) are increasingly gaining momentum as a key driver for the transition towards a low-carbon society (REN21 2016) and a source of technological and social innovation. The deployment of RE and its integration in large-scale power generation systems has been progressively driven by supportive policy frameworks adopted by pioneering countries such as Germany, Spain and France. This has subsequently fostered a process of learning and spreading of policies between leading countries and other governments willing to implement RE support schemes. Within the field of comparative public policy, different but interrelated approaches of the phenomenon of policy spreading have been developed, among which the most rehearsed are policy diffusion, policy transfer, policy convergence and lesson-drawing. The present study addresses a specific case of policy transfer between Germany-Spain and Peru for the implementation in the latter of a policy framework to foster the development of RE technologies (Legislative Decree 1002) in 2008, and the subsequent adoption of a support policy mechanism, Renewable Auctions (RA) in 2009. The assessment of the policy transfer process has been carried out by applying the Dolowitz and Marsh Model (Dolowitz and Marsh 1996, 2000). Furthermore, an exploratory analysis of the impacts of the policy transfer process in the development of the Peruvian Solar PV technology innovation system has been conducted in order to assess the outcomes of the policy transfer process in terms of RE technological deployment in the country, tackling Solar PV as the RE technology in focus. For this purpose, a simplified adaptation of the technology innovation system framework (TIS) developed by Hekkert et al. 2007 and Bergek et al 2008 has been employed. The results of the study show that the transfer of knowledge related to RE policy-making involved both voluntary and coercive causes. The drivers for the occurrence of policy transfer were the pressure exerted by a foreigner actor (US) for the enforcement of the RE policy framework (LD 1002) in Peru and the institutional support provided by a “convinced bureaucrat” (the former Vice Minister of Energy). The choice of adopting RA instead of other instruments such as Feed-in-tariffs or Feed-in-premiums is related to the know-how of the country in terms of infrastructure investments and its traditional “modus-operandi”, the availability of natural and financial resources within the country, the perception of technical and financial risks, the negative lessons drawn from the experiences of Spain and Germany regarding the implementation of FITs, and the current state of development of the global RE sector. The policy transfer process has contributed to the development of some components of the Peruvian Solar PV innovation system. From a structural point of view, it has triggered a diversification of the actors involved, mainly driven by the incorporation of large foreign companies specialized in RE, as well as conventional energy companies that have diversified their core activities towards RE. From a dynamic perspective, the implementation of RA has promoted the increase in Solar PV installed capacity and its contribution to the electricity mix, promoting chiefly the function of market formation.
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Morse, Anthony T. "The transfer of oil and gas technology skills to the conceptual design and development of a novel low cost modular Tidal Energy Conversion deployment system". Thesis, Robert Gordon University, 2011. http://hdl.handle.net/10059/798.
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This thesis outlines the use of a new design of Tidal Energy Conversion device which has application in near shore shallow water. The design is applicable for use by coastal communities, either to generate revenue through power sales or just a stand alone system to generate off grid electricity. Previous work conducted on large scale tidal installations have shown that they suffer from excessive costs and time lines, due to their up front design philosophy. This thesis discusses the reasons behind such cost/time overruns and concludes that several technologies and techniques can be incorporated from the subsea oil and gas industry. The early ethos in the offshore oil industry in the 1970’s and 1980’s was to build large offshore structures such as steel and concrete platforms. This has now been replaced by a field development philosophy that looks at simple lower cost subsea well infrastructure as the most cost effective route to exploit a reservoir. The emerging tidal industry has not learned this lesson, yet. A set of new Tidal Energy exploitation designs are proposed and Patented. The chief advantages of this new design are their modular nature, fabrication simplicity, lower build and installation cost. Prototype work is described and further work also highlighted.
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Pokorná, Jana. "Vliv provedení zateplení rodinného domu ve Slavicích na výdaje spojené s provozem této nemovitosti". Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-233085.
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This master´s thesis deals with insulation of the house and it's costs. First part describes the energy performance of building, different methods of thermal insulation and types of thermal isolation. This thesis evaluates the influence of thermal insulation of residential building design for expenses associated with operating the property. This thesis uncludes thermal technical assessment of the condition of the house and then heat the assessment of the options for the thermal insulation on its economic return. In conclusion, the assessment of individual variants insulation is calculated as a simple payback period and the effect on price of this house.
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Richard, Scott J. "A Study on the Integration of a Novel Absorption Chiller into a Microscale Combined Cooling, Heating, and Power (Micro-CCHP) System". ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1765.
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This study explores the application of micro-CCHP systems that utilize a 30 kW gas microturbine and an absorption chiller. Engineering Equation Solver (EES) is used to model a novel single-effect and double-effect water-lithium bromide absorption chiller that integrates the heat recovery unit and cooling tower of a conventional CCHP system into the chiller’s design, reducing the cost and footprint of the system. The results of the EES model are used to perform heat and material balances for the micro-CCHP systems employing the novel integrated chillers, and energy budgets for these systems are developed. While the thermal performance of existing CCHP systems range from 50-70%, the resulting thermal performance of the new systems in this study can double those previously documented. The size of the new system can be significantly reduced to less than one third the size of the existing system.
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Labounek, Martin. "Vliv provedení zateplení rodinného domu na výdaje spojené s jeho provozem". Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254235.
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This diploma thesis deals with insulation of the house and it's costs. First part relates to the developement of the construction, the current trends in the construction of houses, prices of energy and heating options. Next part relates with insulation system ETICS, the way of it's implementation and thermal assessment with basic names. Thermal insulation is designed in six variants. The work includes thermal assessment in original condition and the assessment of new condition modified by adding thermal insulation with it's economic return. In conclusion, the diploma thesis evaluates the payback period of insulation.
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Vogt, Johannes Paul y Jana Kertzscher. "Induktives Ladesystem für den Einsatz in autonomen Verleihstationen". TU Bergakademie Freiberg, 2019. https://tubaf.qucosa.de/id/qucosa%3A38461.
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Der vorliegende Beitrag beschreibt das Konzept eines induktiven Ladesystems für autonome Verleihstationen. Unter Beachtung der Betriebsanforderungen wird im ersten Teil eine zweckmäßige Spezifikation des Ladesystems erarbeitet. Der zweite Teil beschreibt die Modellierung des Resonanzübertragers, welcher technisch als Prototyp realisiert wurde. Dazu erfolgt die analytische Berechnung der Parameter und Vergleich mit den experimentell bestimmten Parametern am Prototypen.This article describes the concept of an inductive charging system for autonomous sharing stations. In accordance with the operational requirements, a suitable specification of the charging system is developed in the first part of this paper. The second part describes the modelling of the resonant transmitter, which was technically realized as a prototype. For this purpose, the analytical calculation of the parameters and their comparison with the experimentally determined parameters on the presented prototype are carried out.
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Xu, Ye. "Kilowatt Three-phase Rotary Transformer Design for Permanent Magnet DC Motor with On-rotor Drive System". Thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-27781.
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The aim of this thesis is to design a kilowatt three-phase step-down rotary transformer for a permanent magnet DC motor. The permanent magnet DC motor has an on-rotor drive system, and therefore requiring a power supply that can transfer power to its drive unit without mechanical contact. The rotary transformer has a detached magnetic coupling structure that qualifies it as a potential method for the wireless power transfer. This thesis studies the rotary transformer as a static device, focusing on its core loss. By using a transient finite element analysis of COMSOL Multiphysics and an iron loss prediction model, the rotary transformer was optimized in terms of efficiency and power density for the on-rotor drive system through proper material selection and geometry exploration. After this, a mechanical design, which based on a literature review of the influences of manufacturing processes on electrical steels, was proposed for realizing the core fabrication and the rotary transformer assembly. The results show that the rotary transformer can step down 400 V/50 Hz three-phase voltage to 13.15V in a Delta-wye connection and output 1.17kW power over an air-gap of 0.3mm with 95.94% overall efficiency. The proposed mechanical design enables the transformer to minimize the core loss and the manufacturing cost. Without using resonant inductive coupling, this transformer design simplifies the power supply for the motor, thereby decreasing the motor manufacturing and maintenance cost.
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Parra, Gustavo Gimenez. "Interação de pontos quânticos com fotossensibilizadores orgânicos na presença de estruturas nano-organizadas". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-07042015-114512/.
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O sucesso de tratamento de câncer depende do seu diagnóstico e tratamento nas etapas iniciais da doença. Isso estimula a busca de novos métodos de diagnóstico e de tratamento sensíveis e tecnicamente simples. Entre esses métodos, o diagnóstico por fluorescência (DPF) e a fotoquimioterapia (FQT) atraem uma atenção especial, sendo não invasivos, sensíveis e fácil de usar. Os fotossensibilizadores (FS) atualmente utilizados em DPF e FQT são corantes orgânicos, os quais possuem algumas desvantagens, tais como instabilidade fotoquímica e baixa seletividade. Os pontos quânticos (PQ) são candidatos promissores para substituírem os FS clássicos por serem fotoestáveis, apresentarem amplo e intenso espectro de absorção óptica e luminescência com alto rendimento quântico. Contudo a iteração entre FS clássicos e os PQ pode aumentar a eficiência de ambos devido a transferência de energia entre eles. O objetivo geral deste trabalho foi estudar os processos da interação de FS orgânicos (as porfirinas PPh, TMPyP e TPPS4) com PQs (CdTe e CdSe/ZnS), funcionalizados com diferentes grupos, em solução aquosa e na presença de modelos nano-organizados de estruturas biológicas com a finalidade de avaliar seu potencial para aplicação em Fotoquimioterapia e Diagnóstico por Fluorescência. Dedicamos especial atenção aos processos de transferência de energia e de carga entre os PQs e os FS. Os PQs interagem efetivamente com as PPh, cuja interação se manifesta pelas mudanças da intensidade e do perfil dos espectros e das curvas de decaimento da luminescência de PQ e da porfirina, do tamanho das partículas espalhadoras na solução, do potencial zeta dentre outros parâmetros espectroscópicos e físico-químicos. Dentro das soluções aquosas homogêneas, o PQ e as PPh podem formar agregados mistos (PQ&PPh&PQ) ou simples (PQ&PPh) e a interação entre eles realiza-se através de mecanismos de curto e/ou longo alcance, dependendo do grupo funcional do PQ. Entretanto, a interação eletrostática repulsiva entre o PQ e outro composto pode estimular a desagregação dos PQs induzindo o aumento na intensidade da sua luminescência e do seu tempo de vida, provocando um aumento na contribuição dos tempos longos do decaimento da luminescência associados com a superfície do PQ. Essas relações entre o tipo de interação do PQ e da PPh podem ser extrapoladas aos sistemas que contêm PQ na presença de estruturas nano-organizadas.The success of cancer treatment depends on the diagnosis and treatment in the early stages of the disease. This stimulates the research for new methods of sensitive diagnosis and technically simple treatment. Among these methods, the Optical Bioimaging by fluorescence (OBI) and Photochemotherapy (PCT) attract special attention, being non-invasive, sensitive and friendly use. The photosensitizers (PS) currently used in the OBI-PCT are organic dyes, which have some drawbacks such as photochemical instability and low selectivity. Quantum Dots (QD) are promising candidates to replace the classic PS being photostable, present broad and intensive spectrum of optical absorption and luminescence and, high quantum yield. Therefore the interaction between QDPS and the classic PS can increase the efficiency of both due to energy transfer between them. The aim of this work was to study the processes of organic PS interaction (porphyrins PPh, TMPyP and TPPS4) with QDs (CdTe and CdSe/ZnS), functionalized with different groups in aqueous solution and in the presence of nano-organized models of biological structures with order to evaluate its potential for use in Photochemotherapy and Optical Bioimaging. We devote special attention to energy transfer processes and cargo between the QDs and PS. The QDs effectively interact with PPh, whose interaction is manifested by changes in the intensity and profile of spectra and luminescence decay curves of QD and the porphyrin, the linear size of the scattering particles in the solution, the zeta potential among other spectroscopic and physical chemistry parameters. Within the homogeneous aqueous solutions, QD and Pph can form mixed aggregates (QD&PPh&QD) or simple (QD&PPh) and the interaction between them is carried out through short mechanisms and/or long range, depending on the functional group of the QD. However, the repulsive electrostatic interaction between the QD and another compound may stimulate the breakdown of QDs inducing the increase in the intensity of their luminescence and its lifetime, causing an increase in the contribution of long time decay of the luminescence associated with the surface of QD. These relationships between the type of interaction of the QD and PPh can be extrapolated to systems containing QD in the presence of nano-organized structures.
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Batrla, Jan. "Vliv provedení zateplení na rodinném domě v obci Karolínka na výdaje spojené s provozem této nemovitosti". Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-233054.
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This thesis evaluates the influence of thermal insulation of a detached house on the expenses associated with the operation of the property. The first part describes the construction of houses from history to the present day, as well as legislation associated with the thermal insulation of buildings. The work also deals with the energy performance of buildings, energy price developments, types of thermal isolation and insulation of Houses. Thoroughly analyzes ETICS insulation systém. The second part is devoted to a particular detached house in the village Karolinka to evaluate the economic return on investment. Thermal insulation is solved in seven variants. The work includes thermal technical assessment of the condition of the original house and then heat the assessment of the options for the thermal insulation on its economic return. In conclusion, the assessment of individual variants insulation is calculated as a simple payback period.
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Asef, Pedram. "Multi-level-objective design optimization of permanent magnet synchronous wind generator and solar photovoltaic system for an urban environment application". Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/665396.
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This Ph.D. thesis illustrates a novel study on the analytical and numerical design optimization of radial-flux permanent magnet synchronous wind generators (PMSGs) for small power generation in an urban area, in which an outer rotor topology with a closed-slot stator is employed. The electromagnetic advantages of a double-layer fractional concentration non-overlapping winding configuration are discussed. The analytical behavior of a PMSG is studied in detail; especially for magnetic flux density distribution, time and space harmonics, flux linkages, back-EMF, cogging torque, torque, output power, efficiency, and iron losses computation. The electromagnetic behavior of PMSGs are evaluated when a number of various Halbach array magnetization topologies are presented to maximize the generator’s performance. In addition, the thermal behavior of the PMSG is improved using an innovative natural air-cooling system for rated speed and higher to decrease the machine’s heat mainly at the stator teeth. The analytical investigation is verified via 2-D and 3-D finite element analysis along with a good experimental agreement.
Design optimization of electrical machines plays the deterministic role in performance improvements such as the magnetization pattern, output power, and efficiency maximization, as well as losses and material cost minimization. This dissertation proposes a novel multi-objective design optimization technique using a dual-level response surface methodology (D-RSM) and Booth’s algorithm (coupled to a memetic algorithm known as simulated annealing) to maximize the output power and minimize material cost through sizing optimization. Additionally, the efficiency maximization by D-RSM is investigated while the PMSG and drive system are on duty as the whole. It is shown that a better fit is available when utilizing modern design functions such as mixed-resolution central composite (MR-CCD) and mixed-resolution robust (MR-RD), due to controllable and uncontrollable design treatments, and also a Window-Zoom-in approach. The proposed design optimization was verified by an experimental investigation. Additionally, there are several novel studies on vibro-acoustic design optimization of the PMSGs with considering variable speed analysis and natural frequencies using two techniques to minimize the magnetic noise and vibrations.
Photovoltaic system design optimization considered of 3-D modeling of an innovative application-oriented urban environment structure, a smart tree for small power generation. The horizon shading is modeled as a broken line superimposed onto the sun path diagram, which can hold any number of height/azimuth points in this original study. The horizon profile is designed for a specific location on the Barcelona coast in Spain and the meteorological data regarding the location of the project was also considered. Furthermore, the input weather data is observed and stored for the whole year (in 2016). These data include, ambient temperature, module’s temperature (open and closed circuits tests), and shading average rate. A novel Pareto-based 3-D analysis was used to identify complete and partial shading of the photovoltaic system. A significant parameter for a photovoltaic (PV) module operation is the nominal operating cell temperature (NOCT). In this research, a glass/glass module has been referenced to the environment based on IEC61215 via a closed-circuit and a resistive load to ensure the module operates at the maximum power point. The proposed technique in this comparative study attempts to minimize the losses in a certain area with improved output energy without compromising the overall efficiency of the system. A Maximum Power Point Track (MPPT) controller is enhanced by utilizing an advanced perturb & observe (P&O) algorithm to maintain the PV operating point at its maximum output under different temperatures and insolation. The most cost-effective design of the PV module is achieved via optimizing installation parameters such as tilt angle, pitch, and shading to improve the energy yield. The variation of un-replicated factorials using a Window-Zoom-in approach is examined to determine the parameter settings and to check the suitability of the design. An experimental investigation was carried out to verify the 3-D shading analysis and NOCT technique for an open-circuit and grid-connected PV module.Esta tesis muestra un novedoso estudio referente al diseño optimizado de forma analítica y numérica de un generador síncrono de imanes permanentes (PMSGs) para una aplicación de microgeneración eólica en un entorno urbano, donde se ha escogido una topología de rotor exterior con un estator de ranuras cerradas. Las ventajas electromagnéticas de los arrollamientos fraccionarios de doble capa, con bobinas concentradas se discuten ampliamente en la parte inicial del diseño del mismo, así como las características de distribución de la inducción, los armónicos espaciales y temporales, la fem generada, el par de cogging así como las características de salida (par, potencia generada, la eficiencia y la distribución y cálculo de las pérdidas en el hierro que son analizadas detalladamente) Posteriormente se evalúan diferentes configuraciones de estructuras de imanes con magnetización Halbach con el fin de maximizar las prestaciones del generador. Adicionalmente se analiza la distribución de temperaturas y su mejora mediante el uso de un novedoso diseño mediante el uso de ventilación natural para velocidades próximas a la nominal y superiores con el fin de disminuir la temperatura de la máquina, principalmente en el diente estatórico. El cálculo analítico se completa mediante simulaciones 2D y 3D utilizando el método de los elementos finitos así como mediante diversas experiencias que validan los modelos y aproximaciones realizadas. Posteriormente se desarrollan algoritmos de optimización aplicados a variables tales como el tipo de magnetización, la potencia de salida, la eficiencia así como la minimización de las pérdidas y el coste de los materiales empleados. En la tesis se proponen un nuevo diseño optimizado basado en una metodología multinivel usando la metodología de superficie de respuesta (D-RSM) y un algoritmo de Booth (maximizando la potencia de salida y minimizando el coste de material empleado) Adicionalmente se investiga la maximización de la eficiencia del generador trabajando conjuntamente con el circuito de salida acoplado. El algoritmo utilizado queda validado mediante la experimentación desarrollada conjuntamente con el mismo. Adicionalmente, se han realizado diversos estudios vibroacústicos trabajando a velocidad variable usando dos técnicas diferentes para reducir el ruido generado y las vibraciones producidas. Posteriormente se considera un sistema fotovoltaico orientado a aplicaciones urbanas que hemos llamado “Smart tree for small power generation” y que consiste en un poste con un generador eólico en la parte superior juntamente con uno o más paneles fotovoltaicos. Este sistema se ha modelado usando metodologías en 3D. Se ha considerado el efecto de las sombras proyectadas por los diversos elementos usando datos meteorológicos y de irradiación solar de la propia ciudad de Barcelona. Usando una metodología basada en un análisis 3D y Pareto se consigue identificar completamente el sistema fotovoltaico; para este sistema se considera la temperatura de la célula fotovoltaica y la carga conectada con el fin de generar un algoritmo de control que permita obtener el punto de trabajo de máxima potencia (MPPT) comprobándose posteriormente el funcionamiento del algoritmo para diversas situaciones de funcionamiento del sistema
La tesis desenvolupa un nou estudi per al disseny optimitzat, analític i numèric, d’un generador síncron d’imants permanents (PMSGs) per a una aplicació de microgeneració eòlica en aplicacions urbanes, on s’ha escollit una configuració amb rotor exterior i estator amb ranures tancades. Es discuteixen de forma extensa els avantatges electromagnètics dels bobinats fraccionaris de doble capa així com les característiques resultats vers la distribució de les induccions, els harmònics espacials i temporals, la fem generada, el parell de cogging i les característiques de sortida (parell, potencia, eficiència i pèrdues) Tanmateix s’afegeix l’estudi de diferents estructures Halbach per als imants permanents a fi i efecte de maximitzar les característiques del generador. Tot seguit s’analitza la distribució de temperatures i la seva reducció mitjançant la utilització d’una nova metodologia basada en la ventilació natural. Els càlculs analítics es complementen mitjançant anàlisi en 2 i 3 dimensions utilitzant elements finits i diverses experiències que validen els models i aproximacions emprades. Una vegada fixada la geometria inicial es desenvolupen algoritmes d’optimització per a diverses variables (tipus de magnetització dels imants, potencia de sortida, eficiència, minimització de pèrdues i cost dels materials) La tesi planteja una optimització multinivell emprant la metodologia de superfície de resposta i un algoritme de Booth; a més, es realitza la optimització considerant el circuit de sortida. L’algoritme resta validat per la experimentació realitzada. Finalment, s’han considerat diversos estudis vibroacústic treballant a velocitat variable, emprant dues tècniques diferents per a reduir el soroll i les vibracions desenvolupades. Per a finalitzar l’estudi es considera un sistema format per una turbina eòlica instal·lada sobre un pal de llum autònom, els panells fotovoltaics corresponents i el sistema de càrrega. Per a modelitzar l’efecte de l’ombrejat s’ha emprat un model en 3D i les dades del temps i d’irradiació solar de la ciutat de Barcelona. El model s’ha identificat completament i s’ha generat un algoritme de control que considera, a més, l’efecte de la temperatura de la cèl·lula fotovoltaica y la càrrega connectada al sistema per tal d’aconseguir el seguiment del punt de màxima potencia
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Bavetta, Ryan A. (Ryan Andrew). "An investigation of didactic energy transfer systems". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40399.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 24).
New experiments were developed for the freshmen seminar Physics of Energy. The class covers electricity generation and dissipation, and provides experience in analysis and design of electrical and mechanical engineering systems. There was interest in developing a series of new laboratory experiments that would demonstrate methods of energy conversion to students. The experiments are focused on the topic of energy conversion and they introduce topics from electromagnetism to mechanical engineering. The new systems developed include a DC motor kit for learning about motor design and use, a linear synchronous motor for learning about electromagnetism, classical mechanics and ballistics, and an end to end power plant energy conversion laboratory to introduce the topics of heat transfer and process efficiencies.
by Ryan A. Bavetta.
S.B.
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Boothby, Clare Elspeth. "Phosphorescence and energy transfer in organometallic systems". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614800.
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Kang, Ji-Hwan. "Energy transfer enhancement of photon upconversion systems for solar energy harvesting". Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45846.
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Photon energy upconversion (UC), a process that can convert two or more photons with low energy to a single photon of higher energy, has the potential for overcoming the thermodynamic efficiency limits of sunlight-powered devices and processes. An attractive route to lowering the incident power density for UC lies in harnessing energy transfer through triplet-triplet annihilation (TTA). To maximize energy migration in multicomponent TTA-assisted UC systems, triplet exciton diffusivity of the chromophores within an inert medium is of paramount importance, especially in a solid-state matrix for practical device integration.
In this thesis, low-threshold sensitized UC systems were fabricated and demonstrated by a photo-induced interfacial polymerization within a coaxial-flow microfluidic channel and in combination with nanostructured optical semiconductors. Dual-phase structured uniform UC capsules allow for the highly efficient bimolecular interactions required for TTA-based upconversion, as well as mechanical strength for integrity and stability. Through controlled interfacial photopolymerization, diffusive energy transfer-driven photoluminescence in a bi-molecular UC system was explored with concomitant tuning of the capsule properties. We believe that this core-shell structure has significance not only for enabling promising applications in photovoltaic devices and photochromic displays, but also for providing a useful platform for photocatalytic and photosensor units.
Furthermore, for improving photon upconverted emission, a photonic crystal was integrated as an optical structure consisting of monodisperse inorganic colloidal nanoparticles and polymer resin. The constructively enhanced reflected light allows for the reuse of solar photons over a broad spectrum, resulting in an increase in the power conversion efficiency of a dye-sensitized solar cell as much as 15-20 %.
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McGee, Seán. "Thermal energy management and chemical reaction investigation of micro-proton exchange membrane fuel cell and fuel cell system using finite element modelling". Thesis, KTH, Kraft- och värmeteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173001.
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Fuel cell systems are becoming more commonplace as a power generation method and are being researched, developed, and explored for commercial use, including portable fuel cells that appear in laptops, phones, and of course, chargers. This thesis examines a model constructed on inspiration from the myFC PowerTrekk, a portable fuel cell charger, using COMSOL Multiphysics, a finite element analysis software. As an educational tool and in the form of zero-dimensional, two-dimensional, and three-dimensional models, an investigation was completed into the geometric construction, air conditions and compositions, and product materials with a best case scenario completed that summarizes the results identified. On the basis of the results of this research, it can be concluded that polyoximetylen and high-density polyethylene were considered as possible materials for the majority of the product, though a more thorough investigation is needed. Air flow of above 10 m/s, air water vapour mass fraction below 50% and initial temperature between 308K and 298K was considered in this best scenario. Suggestions on future expansions to this project are also given in the conclusion.