Rozprawy doktorskie: „Hybride uav”

1

Sansou, Florian. "Contrôle actif d'un micro-drone convertible face à la turbulence". Electronic Thesis or Diss., Toulouse, École nationale de l’aviation civile, 2024. https://enac.hal.science.

Pełny tekst źródła

Streszczenie:

L'objectif du projet CATMAV est d'étudier le contrôle d'un micro-drone de type « tilt-wing » en environnement turbulent. La configuration générale est basée sur le principe d'un drone avion avec un fuselage classique dont l'aile est capable de basculer au cours du vol. Ce type de configuration convertible a de nombreux atouts dont une capacité de décollage et atterrissage vertical tout en gardant de bonnes performances en vol de croisière. Une importante limitation est la robustesse en présence de turbulences, notamment en milieu urbain, montagneux ou maritime. Une des innovations de ce projet est l'utilisation d'une sonde capable de mesurer le vecteur vent local ainsi que les turbulences. Ce capteur est en cours de développement au sein du programme drone de l'Enac
This PhD thesis aims at studying the control of a tilt-wing mini-UAV in turbulent environments. This type of configuration has many benefits with the capability to takeoff and land vertically while keeping good flight performances and the main body of the plane stays horizontal. However, it may be highly sensitive to wind gust and turbulences, especially in urban, mountain or maritime areas. The main objective is to contribute to the safety and flight performances of this type of flying platform. The UAV Program at Enac is currently developing a 5-hole probe to be used as a local wind and turbulence sensor. The work will concentrate on the integration of these aerological data into the control laws to achieve a faster and better dynamic response to gusts

Style APA, Harvard, Vancouver, ISO itp.

2

Hung, David, Kennon McKeever i Ricardo Ramirez. "HYBRID AUTOMATED UAV TARGET RECOGNITION SYSTEM". International Foundation for Telemetering, 2017. http://hdl.handle.net/10150/626985.

Pełny tekst źródła

Streszczenie:

Accurate image classification is one of the core challenges in computer vision. At the annual AUVSI SUAS competition, this challenge is faced in the form of ground target classification from an unmanned aerial vehicle (UAV). Additionally, due to the constraints imposed by the UAV platform, the system design must consider factors such as size, weight, and power consumption. To meet performance requirements while respecting such limitations, the system was broken into two subsystems: an onboard subsystem and a ground based subsystem. This design allows the onboard subsystem, comprised of a DSLR camera and single-board computer, to capture ground target images and perform rudimentary target detection and localization. For further processing and to ultimately classify the targets in each image, data packets are sent to the ground-based subsystem via a 5 GHz wireless link. Convolutional networks are utilized on the ground to achieve state-of-the-art accuracy in classification.

Style APA, Harvard, Vancouver, ISO itp.

3

Song, H. "A hybrid martian VTOL UAV: design, dynamics and control". Thesis, University of Surrey, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493040.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

4

Meyer, Danielle L. "Energy Optimization of a Hybrid Unmanned Aerial Vehicle (UAV)". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523493111005807.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

5

Thotakura, Sushant. "CO-Design of a Group-5 Power-Split Hybrid Electric UAV". University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613750848692102.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

6

Sommer-Marquez, Alicia Estela. "Retención de clorofila en Hidrotalcitas". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2013. http://www.theses.fr/2013ENCM0002/document.

Pełny tekst źródła

Streszczenie:

Dans les expériences modélisant la photosynthèse, une bonne dispersion des molécules de chlorophylle est requise. Afin d'obtenir cette bonne dispersion, une solution consiste à les ancrer à un hôte. Dans cette étude, des nouveaux matériaux hybrides sont synthétisés en utilisant des hydrotalcites et un dérivé de la chlorophylle : la chlorophylline. La chlorophylline est incorporée et dispersée dans les hydrotalcites par co-précipitation ou pendant la reconstruction des hydrotalcites. Dans cette thèse est également discuté l'effet d'une irradiation par micro-onde. Dans tous les cas sont obtenus des matériaux stables, où les molécules de chlorophylline sont isolées et liées aux hydrotaltices par des liaisons avec les groupes hydroxy OH. Dans ce travail, de nouveaux matériaux sont synthétisés en utilisant les hydrotalcites et la chlorophylle a. Dans ce cas là, il est mis en valeur que la stabilisation de la chlorophylle a peut dépendre du support, à la fois par la nature et le rapport des métaux constituants les hydrotalcites. Ces matériaux hybrides obtenus (chlorophylle a/hydrotalcites) sont également stables. Ces matériaux ont été testés par lixiviation à l'acétone. Dans tous les cas, les composés lixiviés sont de la chlorophylle a, montrant ainsi que la nature et la composition des molécules sont préservées même après trente jours, bien qu'il soit à noter que dans le cas des hydrotalcites Ni/Al une faible fraction de la chlorophylle est décomposée en phéophytine. Finalement, bien que les hydrotalcites soient des composés relativement simples, ils s'avèrent tout à fait adaptés pour empêcher la dégradation des molécules de chlorophylle
In experiments modeling photosynthesis, well dispersed chlorophyll molecules are required. A solution could be to anchor them on some host. In this work, new hybrid materials are synthesized using hydrotalcite and a chlorophyll derivative : chlorophyllin. Chlorophyllin is incorporated and dispersed in hydrotalcite through simultaneous precipitation or during hydrotalcite reconstruction. The effect of microwave irradiation on the crystallization step is discussed. In all cases stable materials are obtained, chlorophyllin molecules are isolated and bonded through hydrotalcite OH groups. Also new hybrid materials are synthesized using hydrotalcites and chlorophyll a. The effect of the support composition on chlorophyll a stabilization is discussed. The stability of the adsorbed chlorophyll a is affected by the support nature and the metal ratio of the hydrotalcite. The obtained hybrid compounds (chlorophyll a on hydrotalcite) are stable. Those hybrids were tested in lixiviation with acetone. In all cases, the lixiviated compound was chlorophyll a showing that the composition and nature of the molecule was preserved even after thirty days, although Ni/Al hydrotalcites decomposed a small fraction of the chlorophyll to pheophytin. Hydrotalcites being basic compounds turn out to be an adequate material to avoid degradation of chlorophyll molecules

Style APA, Harvard, Vancouver, ISO itp.

7

Glassock, Richard R. "Design, modelling and measurement of hybrid powerplant for unmanned aerial vehicles (UAVs)". Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/61052/1/Richard_Glassock_Thesis.pdf.

Pełny tekst źródła

Streszczenie:

The success or effectiveness for any aircraft design is a function of many trade-offs. Over the last 100 years of aircraft design these trade-offs have been optimized and dominant aircraft design philosophies have emerged. Pilotless aircraft (or uninhabited airborne systems, UAS) present new challenges in the optimization of their configuration. Recent developments in battery and motor technology have seen an upsurge in the utility and performance of electric powered aircraft. Thus, the opportunity to explore hybrid-electric aircraft powerplant configurations is compelling. This thesis considers the design of such a configuration from an overall propulsive, and energy efficiency perspective. A prototype system was constructed using a representative small UAS internal combustion engine (10cc methanol two-stroke) and a 600W brushless Direct current (BLDC) motor. These components were chosen to be representative of those that would be found on typical small UAS. The system was tested on a dynamometer in a wind-tunnel and the results show an improvement in overall propulsive efficiency of 17% when compared to a non-hybrid powerplant. In this case, the improvement results from the utilization of a larger propeller that the hybrid solution allows, which shows that general efficiency improvements are possible using hybrid configurations for aircraft propulsion. Additionally this approach provides new improvements in operational and mission flexibility (such as the provision of self-starting) which are outlined in the thesis. Specifically, the opportunity to use the windmilling propeller for energy regeneration was explored. It was found (in the prototype configuration) that significant power (60W) is recoverable in a steep dive, and although the efficiency of regeneration is low, the capability can allow several options for improved mission viability. The thesis concludes with the general statement that a hybrid powerplant improves the overall mission effectiveness and propulsive efficiency of small UAS.

Style APA, Harvard, Vancouver, ISO itp.

8

Arantes, Márcio da Silva. "Hybrid qualitative state plan problem and mission planning with UAVs". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-05122017-083420/.

Pełny tekst źródła

Streszczenie:

This paper aims to present the thesis developed in the Doctoral Programin Computer Science and Computational Mathematics of the ICMC/USP. The thesis theme seeks to advance the state of the art by solving the problems of scalability and representation present in mission planning algorithms for Unmanned Aerial Vehicle (UAV). Techniques based on mathematical programming and evolutionary computation are proposed. Articles have been published, submitted or they are in final stages of preparation.These studies report the most significant advances in the representation and scalability of this problem. Mission planners worked on the thesis deal with stochastic problems in non-convex environments,where collision risks or failures in mission planning are treated and limited to a tolerated value. The advances in the representation allowed to solve violations in the risks present in the original literature modeling, besides making the models more realistic when incorporating aspects such as effects of the air resistance. Efficient mathematical modeling techniques allowed to advance from a Mixed Integer Nonlinear Programming (MINLP) model, originally proposed in the literature, to a Mixed Integer Linear Programming (MILP) problem. Modeling as a MILP led to problem solving more efficiently through the branch-and-algorithm. The proposed new representations resulted in improvements from scalability, solving more complex problems within a shorter computational time. In addition, advances in scalability are even more effective when techniques combining mathematical programming and metaheuristics have been applied to the problem.
O presente documento tem por objetivo apresentar a tese desenvolvida no Programade Doutorado em Ciência da Computação e Matemática Computacional do ICMC/USP. O tema da tese busca avançar o estado da arte ao resolver os problemas de escalabilidade e representação presentes em algoritmos de planejamento para missões com Veículos Aéreos Não Tripulados (VANTs). Técnicas baseadas em programação matemática e computação evolutiva são propostas. Artigos foram publicados, submetidos ou se encontram em fase final de elaboração. Esses trabalhos reportamos avanços mais significativos obtidos na representação e escalabilidade deste problema.Os planejadores de missão trabalhados na tese lidam com problemas estocásticos em ambientes não convexos, onde os riscos de colisão ou falhas no planejamento da missão são tratados e limitados a um valor tolerado. Os avanços na representação permitiram solucionar violações nos riscos presentes na modelagem original, além de tornar os modelos mais realistas ao incorporar aspectos como efeitos da resistência do ar. Para isso, técnicas eficientes de modelagem matemática permitiram avançar de um modelo de Programação Não-Linear Inteira Mista(PNLIM), originalmente proposto na literatura, para um problema de Programação Linear Inteira Mista (PLIM). A modelagem como um PLIM levou à resolução do problema de forma mais eficiente através do algoritmo branch-and-cut. As novas representações propostas resultaram em melhorias na escalabilidade, solucionando problemas mais complexos em um tempo computacional menor.Além disso,os avanços em escalabilidade mostraram-se mais efetivos quando técnicas combinando programação matemática e metaheurísticas foram aplicadas ao problema.

Style APA, Harvard, Vancouver, ISO itp.

9

Allouche, Abdel Rahman. "Growth dynamics of Hybrid halide perovskite layers and its precursors in UHV : atomic scale insight from real-time Grazing Incidence Fast Atom Diffraction". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP027.

Pełny tekst źródła

Streszczenie:

Les pérovskites hybrides halogénées se sont révélées très prometteuses pour produire à moindre coût des dispositifs optoélectroniques performants. En tant que matériau actif des cellules solaires, ces matériaux ont désormais atteint un rendement record de conversion de puissance (PCE) de 26 %, similaire à celui du silicium cristallin. Malgré des efforts de recherche importants, de nombreux défis demeurent, notamment sur les problèmes de stabilité, la compréhension du rôle des défauts et enfin sur l’accès à leur dynamique de cristallisation. Pour atteindre ces objectifs, le dépôt sous vide apparaît comme une alternative effective à la méthode conventionnelle par voie humide. En plus de répondre à la problématique majeure de la mise à l’échelle, l’approche sous vide offre un meilleur contrôle de la croissance du film et pourrait potentiellement, par une réduction de la densité des défauts, révéler les mécanismes d’instabilité et simultanément éclaircir le rôle des interfaces. En dépit d’une meilleure qualité structurale, les couches actives déposées sous vide ne donnent pas nécessairement un meilleur PCE que celles produites par la méthode en solution. Cette observation déroutante exige une nouvelle approche dans la caractérisation de la croissance. Nous proposons une méthodologie qui consiste à suivre le processus de croissance en temps réel, idéalement sous ultra-vide (UHV), par une technique sensible à la surface et qui fournit des informations sur le mode de croissance, la structure cristalline, la densité de défauts ainsi que le nombre de monocouches. Pour cela, nous utilisons la diffraction d’atomes rapides en incidence rasante (GIFAD), une technique très douce basée sur la diffusion quantique d'atomes d'hélium à une énergie autour de 1 keV. Contrairement à la diffraction électronique ou de rayons X, les atomes d'hélium sondent ici uniquement la densité électronique au niveau de la lisière de la surface, ce qui rend GIFAD exclusivement sensible à la couche supérieure. En particulier, les données de diffraction, qui contiennent des informations sensibles sur la distribution de la densité électronique au sein de la maille, affichent directement les signes d’une transition de phase sans rupture de symétrie. Des outils complémentaires fournissent des informations complémentaires sur les propriétés chimiques, électroniques et optiques de la couche. Nous avons concentré nos efforts sur la croissance de MAPbI₃ (CH₃NH₃PbI₃) et de ses constituants, MAI (CH₃NH₃I) et PbI₂, à des pressions de base de l’ordre de 10⁻¹⁰ mbar (UHV). Afin de résoudre les tout premiers stade de la croissance et la dynamique d'organisation à l'interface, nous avons sélectionné un métal cristallin, Ag(001), comme substrat. Nos résultats confirment d'abord la remarquable flexibilité de MAI et PbI₂, ils présentent tous deux une croissance quasi-épitaxiale sur Ag(001) pour MAI et sur MAI/Ag(001) pour PbI₂, malgré un fort désaccord des paramètres de maille. Pour PbI₂, la croissance adopte le mode couche par couche avec une contrainte biaxiale s'estompant graduellement jusqu’à la 8ème monocouche. Le résultat le plus remarquable de ce travail est, lors du dépôt de PbI₂ sur MAI/Ag(001), le déclenchement instantanée d’une transformation de la maille cristalline, suivi d’un changement de symétrie dans le plan (carré vers hexagonal), tout en préservant l'ordre à longue distance. Néanmoins, dans nos conditions UHV et sauf sur Ag(001), on observe un très faible coefficient de collage du MAI, même sur une couche de PbI₂ suffisamment épaisse (50 monocouches), ce qui empêche la formation d’une couche de MAPbI₃. Ce travail soulève des questions sur le rôle des impuretés provenant du gaz résiduel lorsque MAPbI₃ est déposé sous vide à des pressions de l’ordre de 10⁻⁷ mbar ou plus
Halide hybrid perovskites have shown great promise for highly efficient and cost-effective optoelectronics devices. As the active material in solar cells, these materials have now reached a record 26% Power Conversion Efficiency (PCE), similar to that of crystalline silicon. Despite significant research efforts, many challenges remain, which include solving the stability issue, understanding the role of defects and achieving a better access to their crystallization dynamics. To meet these objectives, vacuum deposition emerges as a promising alternative to the prevalent solution method. In addition to responding to the major upscaling issue, the vacuum approach offers a much greater control over the film growth and could potentially, by a reduction of the defect density, reveal the instability mechanisms and simultaneously shed some light on the role of interfaces. In spite of improved structural quality, active layers deposited in vacuum do not necessarily yield a better PCE than those produced by the solution method. This puzzling observation calls for a new approach in the growth characterization. Our work proposes a methodology that consists in monitoring the growth process in real-time, ideally in ultra-high vacuum (UHV), by a surface sensitive technique that provides information on the growth mode, the crystalline structure, the defect density as well as the number of grown layers. For that purpose, we use Grazing Incidence Fast Atom Diffraction (GIFAD), a very soft technique based on the quantum scattering of helium atoms at energy around 1 keV. As opposed to electron or X-ray diffraction, here the helium atoms probe only the electron density at the selvage of the surface, making GIFAD exclusively sensitive to the top layer. In particular, the diffraction data, which bears sensitive information on the electron density distribution within the lattice, directly displays signs of phase transitions with no symmetry breaking. Additional tools provide complementary information of the chemical, electronic, and optical properties of the layer. We focused our effort on the growth of MAPbI₃ (CH₃NH₃PbI₃) and its constituents, MAI (CH₃NH₃I) and PbI₂, at base pressures in the low 10⁻¹⁰ mbar range (UHV). To get a better access to the early stage of the growth and to the organization dynamics at the interface, we selected a crystalline metal, Ag(001), as a substrate. Our results first confirm the remarkable flexibility of MAI et PbI₂, they both exhibit a quasi-epitaxial growth on Ag(001) for MAI and on MAI/Ag(001) for PbI₂, despite a large mismatch in lattice parameters. For PbI₂, the growth proceeds layer-by-layer with a biaxial strain gradually fading out at the 8ᵗᵸ monolayer. The most remarkable result of this work is the instantaneous triggering, upon deposition of PbI₂ on MAI/Ag(001), of a continuous transformation of the crystal lattice, followed by a change of symmetry in the plane (square to hexagonal), while preserving long-distance order. However, in our UHV conditions and except on Ag(001), we observe a very low sticking coefficient of MAI, even on a sufficiently thick PbI₂ layer (50 monolayers), which prevents the formation of a MAPbI₃ layer. This work raises questions about the role of impurities from the residual gas when MAPbI₃ is grown at pressures around 10⁻⁷ mbar or higher

Style APA, Harvard, Vancouver, ISO itp.

10

Åkesson, Elsa, Maximilian Kempe, Oskar Nordlander i Rosa Sandén. "Unmanned Aerial Vehicle Powered by Hybrid Propulsion System". Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277115.

Pełny tekst źródła

Streszczenie:

I samband med den globala uppvärmningen ökar efterfrågan för rena och förnybara bränslen alltmer i dagens samhälle. Eftersom flygindustrin idag är ansvarig för samma mängd växthusgaser som all motortrafik i Sverige, skulle ett byte till en avgasfri energikälla för flygfarkoster vara ett stort framsteg. Därför har projektet genom modellering framtagit ett hybridsystem av ett batteri och en bränslecell och undersökt hur kombinationen av olika storlekar på dem presterar i en driftcykel. Då batterier har hög specifik effekt men är tunga, kompletteras de med fördel av bränsleceller, som är lättviktiga och bidrar med uthållig strömförsörjning. På så sätt blir hybriden optimal för flygfarkoster. Kandidatarbetet är en del av projektet Green Raven, ett tvärvetenskapligt samarbete mellan instutitionerna Tillämpad Elektrokemi, Mekatronik och Teknisk Mekanik på Kungliga Tekniska Högskolan. Driftcykelmodelleringen gjordes i Simulink, och flera antaganden gjordes beträffande effektprofilen, samt bränslecellens mätvärden och effekt. Tre olika energihushållningsscheman skapades, vilka bestämde bränslecellseffekten beroende på vätgasnivån och batteriets laddningstillstånd. Skillnaden på systemen var vilka intervall av laddningstillstånd hos batteriet som genererade olika effekt hos bränslecellen. Det bästa alternativet visade sig vara 0/100-systemet, eftersom det var det enda som inte orsakede någon degradering av bränslecellens kapacitet.
In today’s society, with several environmental challenges such as global warming, the demand for cleanand renewable fuels is ever increasing. Since the aviation industry in Sweden is responsible for the sameamount of greenhouse gas emissions as the motor traffic, a change to a non-polluting energy source forflying vehicles would be considerable progress. Therefore, this project has designed a hybrid system of abattery and a fuel cell and investigated how different combinations of battery and fuel cell sizes perform ina drive cycle, through computer modelling. As batteries possess a high specific power but are heavy, thefuel cells with high specific energy complement them with a sustained and lightweight power supply,which makes the hybrid perfect for aviation. The bachelor thesis is a part of Project Green Raven, aninterdisciplinary collaboration with the institutions of Applied Electrochemistry, Mechatronics andEngineering Mechanics at KTH Royal Institute of Techology. The drive cycle simulations were done inSimulink, and several assumptions regarding the power profile, fuel cell measurements and power weremade. Three different energy management strategies were set up, determining the fuel cell powerdepending on hydrogen availability and state of charge of the battery. The strategies were called 35/65,20/80 and 0/100, and the difference between them was at which state of charge intervals the fuel cellchanged its power output. The best strategy proved to be 0/100, since it was the only option which causedno degradation of the fuel cell whatsoever.

Style APA, Harvard, Vancouver, ISO itp.

11

Xu, Jie S. M. Massachusetts Institute of Technology. "Learning to fly : computational controller design for hybrid UAVs with reinforcement learning". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122772.

Pełny tekst źródła

Streszczenie:

Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 51-54).
Hybrid unmanned aerial vehicles (UAV) combine advantages of multicopters and fixed-wing planes: vertical take-off, landing, and low energy use. However, hybrid UAVs are rarely used because controller design is challenging due to its complex, mixed dynamics. In this work, we propose a method to automate this design process by training a mode-free, model-agnostic neural network controller for hybrid UAVs. We present a neural network controller design with a novel error convolution input trained by reinforcement learning. Our controller exhibits two key features: First, it does not distinguish among flying modes, and the same controller structure can be used for copters with various dynamics. Second, our controller works for real models without any additional parameter tuning process, closing the gap between virtual simulation and real fabrication. We demonstrate the efficacy of the proposed controller both in simulation and in our custom-built hybrid UAVs. The experiments show that the controller is robust to exploit the complex dynamics when both rotors and wings are active in flight tests.
by Jie Xu.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

Style APA, Harvard, Vancouver, ISO itp.

12

Jacobsson, David. "Learning to Fly: Upgraded Aerodynamics and Control Surfaces". Thesis, KTH, Flygdynamik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299417.

Pełny tekst źródła

Streszczenie:

In recent times the unmanned quadcopter aircraft has been used for a widening range of applications, but for longer distances it still falls short of conventional airplanes in terms of energy usage. There exists hybrid configurations of unmanned aircraft which combine the mobility of quadcopters and the range of fixed-wing aircraft. The transition between the hovering mode and the gliding mode, however, is a complex non-linear control problem. To solve this a recent study applied a neural network as a closed loop controller. This controller was capable of seamless mode transition and could be trained for any copter configuration using reinforcement learning. The work presented here focuses on improvements to the method of controller design established by said study, mainly focusing on increased realism of the aerodynamic simulations and the addition of control surfaces for increased maneuverability. These improvements resulted in a lift of 37% of the total copter weight and a higher achievable top speed of 8 m/s before instability occurs. To verify these improvements were not only present in the simulations a physical prototype was also constructed which when tested succeeded in hovering flight but failed to sustain any significant forward flight.
På senare tid har obemannade quadcopters kraftigt expanderat sina användningsområden, men för längre sträckor slås de fortfarande av konventionella flygplan när det gäller energiåtgång. Det finns hybridkonfigurationer av obemannade farkoster som kombinerar quadcopterns rörlighet och räckvidden av flygplan. Övergången mellan hovrande läge och horisontell flygning är emellertid ett komplext icke-linjärt reglerproblem. För att lösa detta använde en nyligen genomförd studie ett neuralt nätverk som en regulator i ett återkopplat system. Den här styrenheten kunde sömlöst övergå mellan flyglägen och kunde tränas för valfri copterkonfiguration med hjälp av reinforcement learning. Arbetet som presenteras här fokuserar på förbättringar av metoden för regulatordesign som fastställts av nämnda studie, främst med fokus på ökad realism av de aerodynamiska simuleringarna och tillägget av kontrollytor för ökad manövrerbarhet. Dessa förbättringar resulterade i en genererad lyftkraft upp till 37% av farkostens vikt och en förhöjd maxhastighet till 8 m/s före instabilitet. För att verifiera dessa resultat i verkligheten konstruerades en fysisk prototyp som vid försök lyckades stabilisera sig i hovrande läge men inte upprätthålla någon signifikant framåtfart.

Style APA, Harvard, Vancouver, ISO itp.

13

Berrebi, Mickael. "Développement de vitrages organiques et hybrides à base de réseaux interpénétrés de polymères pour la protection des biens culturels". Thesis, Cergy-Pontoise, 2015. http://www.theses.fr/2015CERG0783/document.

Pełny tekst źródła

Streszczenie:

Ces travaux de thèse se positionnent au cœur des problématiques du patrimoine et notamment de la conservation préventive des œuvres d'art. Pour apporter aux musées une solution à faible coût capable de répondre aux exigences fixées dans le cadre de la protection du patrimoine culturel, nous avons développé de nouveaux vitrages polymères permettant de protéger les œuvres sans en altérer leur perception par le public. Ces matériaux pourront, à terme, tenter de remplacer les vitrages de type poly(méthacrylate de méthyle) (PMMA), très largement utilisés, mais dont le principal inconvénient est sa grande sensibilité à la rayure et aux solvants de nettoyage.Ces matériaux ont été synthétisés en combinant, en différentes proportions, deux polymères, le PMMA et le polycarbonate de CR39® (PCR39®) dans une architecture de réseaux interpénétrés de polymères (RIP). Cette association a permis d'obtenir des nouveaux matériaux transparents (T%>95%) dont la résistance à la rayure et aux solvants est considérablement améliorée comparativement à celle du PMMA. Leurs vieillissements lors de leur exposition à la lumière (UV) artificielle ou naturelle ont été étudiés. Afin d'améliorer leurs propriétés d'anti-rayure, nous avons réticulé sélectivement la phase PMMA avec des nanoparticules de silice fonctionnalisées, ce qui conduit à la réalisation d'un nouveau RIP hybride. Enfin, dans l'optique d'obtenir un matériau intelligent, nous avons étudié la possibilité d'intégrer au sein même de ces vitrages, un capteur de rayonnements UV afin de pouvoir alerter de leur présence. Le PCR39® ayant les propriétés en adéquation avec le développement d'un tel capteur, nous avons ensuite cherché à augmenter la sensibilité du matériau. Pour cela, des composés fluorescents, organique, d'une part et inorganiques d'autre part (nanoparticules d'oxyde de gadolinium dopées soit au terbium soit à l'europium) ont été intégrés au sein des RIP
This work position itself on a primary issue of heritage and more precisely on the preventive conservation of artworks. To provide a low cost solution to museums, capable of meeting the requirements set for the cultural heritage protection, we have developed new polymer glazing to protect works without altering their perception by the public. These materials will eventually be able to replace poly(methyl methacrylate) (PMMA) glazing, which are widely used but have high sensitivity to scratching and cleaning solvents as mains drawbacks.These materials were synthesized by combining, with various proportions, two polymers, PMMA and polycarbonate of CR39® (PCR39®), into an interpenetrating polymer network (IPN) architecture. This association generated new transparent materials (T% > 95%) of which resistance toward scratching and solvents is considerably improved compared to PMMA's one. Their ageing have been studied when exposed to artificial or natural light (UV). To improve their scratch resistance, we selectively crosslinked the PMMA phase with functionalized silica nanoparticles, leading to the formation of a new hybrid IPN. Finally, in order to obtain a smart material, we studied the possibility of integrating within these glazing, a UV sensor to warn of their presence. The PCR39® having properties consistent with the development of such a sensor, we tried to increase the sensitivity of the material. For that purpose, first an organic fluorescent compounds, and secondly an inorganic one (gadolinium oxide nanoparticles doped with terbium or europium) were incorporated in the IPN

Style APA, Harvard, Vancouver, ISO itp.

14

Sinnamon, Ryan R. "Analysis of a Fuel Cell Combustor in a Solid Oxide Fuel Cell Hybrid Gas Turbine Power System for Aerospace Application". Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401189772.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

15

Klímová, Eliška. "Mechanické a transportní vlastnosti hybridních hydrogelových systémů". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444534.

Pełny tekst źródła

Streszczenie:

This master´s thesis deals with the study on mechanical and transport properties of hybrid hydrogel systems. Considering applications of hydrogels, especially in chemical industry, pharmacy, or eventually medical applications, for the study gellan and alginate-based hydrogels were selected. In order to compare individual characteristics physical and hybrid hydrogels were prepared. Gellan hydrogels were prepared in deionization aqua solution, calcium chloride dihydrate and tween 80 solution. Alginate hydrogels were prepared in calcium chloride dihydrate solution as well, and polyacrylamide with N,N´–methylenbisacrylamide. For the study of mechanical properties moisture analyser and rheology measurements were selected. Transport properties were studied using the diffusion experiments combined with UV-VIS spectroscopic detection. Concluding of this thesis is summarization of measured values, which provides comprehensive review of the problematics. It was discovered that the conveniently selected concentrations of structural components of hydrogel matrix and the additives can influence both the mechanical as well as the transport properties of studied hydrogels.

Style APA, Harvard, Vancouver, ISO itp.

16

Gerhard, William Edward III. "Pseudo Doppler Direction Finding System for Localizing Non-Cooperative VHF Transmitters with a Hybrid UAS". Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/92199.

Pełny tekst źródła

Streszczenie:

Current radio direction finding techniques are limited in flexibility and focus on specific applications. Commercial off the shelf systems exist for a wide range of applications from navigation to search and rescue and wildlife tracking. However these systems rely on commercially available VHF receivers and are limited in transmission modulation techniques and frequency ranges. The majority of these systems are expensive which places them outside the reach of most individuals while the current open source designs require specialized skills and knowledge to build. The goal of this work was to design a low cost system capable of determining the approximate location of a non-cooperative VHF transmitter that could easily be implemented on a variety of unmanned systems. One unmanned aerial system was designed, built, and evaluated. Existing open source hardware and software systems were utilized for the development of the pseudo Doppler direction finding system, and work was conducted utilizing recursive Bayesian techniques to estimate the VHF transmitter's location. Results and explanations of system behaviors are presented along with limitations and possible modifications to improve performance and reliability.
Master of Science
Radio direction finding uses specialized radio equipment to determine the direction that a radio signal is coming from. Commercial systems are often expense, and existing hobbyist designs require specialized skills, and both are not flexible in application or frequency. The same is true for commercially available drones, which tend to be expensive or face other limitations. In this work a low cost radio direction finding system that uses easily found open source hardware and software was built and evaluated, along with a low cost unmanned aerial system. Then using the data collected, a computer algorithm was tested that could estimate the transmitting radio’s location. After testing it was determined that all systems did work, but still had room for improvement. Future steps and system modifications are presented that could improve the system’s performance.

Style APA, Harvard, Vancouver, ISO itp.

17

Wang, Xiaojiang. "Polyester Based Hybrid Organic Coatings". University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1340906197.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

18

Sánchez, Camilo André Pereira Contreras. "Manejo de poda em cultivares de uva para processamento /". Botucatu, 2020. http://hdl.handle.net/11449/192361.

Pełny tekst źródła

Streszczenie:

Orientador: Marco Antonio Tecchio
Resumo: Uvas para processamento de suco têm sido implantadas em regiões não tradicionais de produção para atender o aumento do consumo de suco de uva pela população brasileira. Com isso, o estudo do manejo dessas cultivares é imprescindível para a maior produção e qualidade do suco de uva. O objetivo desse estudo foi avaliar as características produtivas e qualitativas de cultivares de uva para processamento, cultivadas em São Manuel, SP, em dois sistemas de poda: curta e mista. O experimento foi realizado no período de agosto de 2017 a janeiro de 2019. Os tratamentos consistiram em três cultivares de uvas para processamento (BRS Violeta, Bordô e BRS Cora) enxertadas sobre o portaenxerto ‘IAC 572’, as quais foram submetidas a dois manejos de poda: poda curta e poda mista, no sistema de condução em espaldeira. Foram avaliadas a fenologia, curva de maturação, a fertilidade de gemas, a produção e produtividade; massas frescas de cacho e engaço; comprimento e largura de cachos e engaços; número de bagas por cacho; massa fresca, comprimento e largura de bagas; número e massa fresca de sementes por baga; sólidos solúveis, acidez titulável, relação SS/AT; pH, antocianinas monoméricas totais, polifenóis totais, flavonoides. O delineamento experimental em esquema fatorial 3 x 2, sendo três cultivares de uva e dois sistemas de poda (poda curta e poda mista), e seis repetições, totalizando 36 parcelas experimentais. A cultivar BRS Cora apresentou maior duração do ciclo fenológico em relação às ... (Resumo completo, clicar acesso eletrônico abaixo)
Mestre

Style APA, Harvard, Vancouver, ISO itp.

19

Garnier, Jérôme. "Elaboration de latex nanostructurés à base de poly(chlorure de vinylidène) par polymérisation en émulsion". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2012. http://www.theses.fr/2012ENCM0011.

Pełny tekst źródła

Streszczenie:

Les emballages alimentaires et pharmaceutiques doivent de nos jours répondre à de nombreux critères : ils doivent non seulement préserver le produit emballé, mais également être inoffensifs, économes en énergie et jetables. Les polymères barrières ont permis de répondre à ces besoins, en offrant des alternatives à des matériaux plus demandeurs en énergie et plus lourds tels que le verre ou les métaux, tout en conservant une faible perméabilité à l’eau et/ou à l’oxygène. Parmi la grande variété de polymères barrières existants, les copolymères du poly(chlorure de vinylidène) (PVDC) offrent une protection plus complète aux contaminants extérieurs, grâce à leurs faibles perméabilités à l’eau et à l’oxygène. Cependant, les films de PVDC sont sujets à des processus de dégradation ayant lieu lors du thermoformage ou sous exposition aux rayonnements UV. Ces effets sont encore plus prononcés dans le cas de films obtenus à partir de latex, dû à des quantités plus importantes d’additifs qui accentueraient les phénomènes de dégradation du polymère. Par conséquent, la synthèse de latex à base de PVDC pour des applications en tant que films barrières aux stabilités thermique et UV améliorées revêt un grand intérêt. Des latex composites à base de PVDC ont tout d’abord été synthétisés en présence de latex semences à fonctionnalité époxy en vue d’améliorer la stabilité thermique du polymère. En effet, les groupements époxy jouent le rôle de stabilisants thermiques en piégeant le chlorure d’hydrogène, dégagé lors du thermoformage et présentant un effet catalytique indirect sur le processus de dégradation du polymère. Dans une première étape, des latex semences à fonctionnalité époxy ont été synthétisés par copolymérisation en émulsion du methacrylate de glycidyle (GMA) et du methacrylate de butyle (BMA). Lors d’une seconde étape, la copolymérisation en émulsion ensemencée du chlorure de vinylidene et de l’acrylate de méthyle a été effectuée en présence des semences de poly(GMA-co-BMA). Des analyses thermogravimétriques effectuées sur les échantillons composites ont mis en évidence le rôle de stabilisant thermique joué par les fonctions époxy. La seconde partie du projet concerne la synthèse de latex hybrides à base d’oxyde de cérium (CeO2) afin d’améliorer la résistance du PVDC aux rayonnements UV. Les nanoparticules d’oxyde de cérium sont en effet attrayantes en tant que stabilisants UV en raison de leur haute absorption des rayonnements UV et d'une faible activité photocatalytique. Cependant, étant donné l’incompatibilité intrinsèque entre les phases inorganique et organique, la synthèse de latex hybrides requiert souvent une étape préliminaire de modification de surface des particules minérales. Le greffage d’alcoxysilanes a d’abord été entrepris sur des particules d’oxyde de cérium afin d’encourager la réaction de polymérisation à leur surface. Des observations par cryo-Microscopie Electronique à Transmission (cryo-MET) effectuées sur les latex hybrides obtenus par cette stratégie ont montré que le greffage d’alcoxysilanes ne permettait pas d’améliorer efficacement la compatibilité entre les phases inorganique et polymère. Enfin, des macro-agents RAFT amphiphatiques ont été employés comme agents comptabilisant réactifs afin de promouvoir la réaction de polymérisation à la surface de l’oxyde de cérium. Des oligomères RAFT ont été obtenus par des réactions de co- ou terpolymérisation en présence d’un agent de contrôle RAFT. Après caractérisation de l’adsorption des macro-agents RAFT à la surface de l’oxyde de cérium, les particules modifiées ont été utilisées dans des réactions de polymérisation en émulsion. Les observations des latex hybrides par cryo-MET ont confirmé l’efficacité de la méthode pour l’obtention de structures hybrides. Cette stratégie semble ainsi la plus prometteuse pour la synthèse de latex hybrides CeO2/PVDC pour des applications en tant que films barrières présentant une stabilité UV améliorée
Food and pharmaceutical packages should nowadays fulfill a wide range of requirements : not only should they preserve the packed products from external polluting agents, but they must also be innocuous, more energy-efficient and disposable. Barrier polymers have enabled to meet these criteria, by offering alternatives to more energy-consuming and heavier materials like glass or metals, while maintaining a low permeability to water and/or oxygen. Among the large variety of barrier polymers, poly(vinylidene chloride) (PVDC) copolymers provide a more complete protection to external contaminants, due to their extremely low permeabilities towards water and oxygen. Nonetheless, PVDC films still suffer from limitations as far as their thermal and UV stabilities are concerned. This effect is even more pronounced in the case of films obtained from latexes, due to the presence of higher amounts of additives that could take part in the polymer degradation. Therefore, the synthesis of PVDC-based latexes for use as waterborne barrier films with improved thermal and UV stabilities are of great importance. PVDC-based composite latexes were first synthesized from epoxy-functionalized seed latexes in order to enhance the polymer thermal stability. Given that hydrogen chloride displays an indirect catalytic effect on the polymer degradation, epoxy groups were indeed expected to act as thermal stabilizers by scavenging the HCl released by the polymer under thermal stress. In a first step, epoxy-functionalized seed latexes were synthesized via the emulsion copolymerization of glycidyl methacrylate (GMA) and butyl methacrylate (BMA). In a second step, the seeded emulsion copolymerization of vinylidene chloride and methyl acrylate was carried out in the presence of poly(GMA-co-BMA) seed latexes. Thermogravimetric analyses carried out on the resulting composite samples evidenced the thermal stabilization provided by epoxy groups. The second part of the project focused on the synthesis of cerium oxide-based hybrid latexes so as to improve the stability of PVDC to UV radiation. Cerium oxide (CeO2) nanoparticles are indeed very attractive as UV-stabilizers due to their high absorption of radiation in the UV range and a low photocatalytic activity. However, due to the intrinsic incompatibility between inorganic and polymer phases, the synthesis of inorganic-organic hybrid latexes often requires a preliminary step of modification of the mineral particles surface. The grafting of alkoxysilanes onto nanoceria was first attempted in order to promote the polymerization reaction at the surface of the inorganic particles. Cryo-Transmission Electron Microscopy (cryo-TEM) observations of hybrid latexes obtained via this route showed that this strategy was unsuccessful at improving the compatibility between the inorganic and polymer phases. Amphiphatic macro-RAFT agents were finally considered as reactive compatibilizing agents to direct the polymerization towards the cerium oxide surface. RAFT oligomers were first obtained by co- or terpolymerization reactions in the presence of a RAFT controlling agent. After characterizing the adsorption of amphiphatic macro-RAFT agents at the surface of nanoceria, surface-modified cerium oxide particles were then engaged in reactions of emulsion polymerization reactions. In most cases, cryo-TEM observations carried out on the resulting latexes confirmed the efficiency of the amphiphatic macro-RAFT agent route for the synthesis of hybrid structures. Therefore this route appeared so far to be the most promising for the synthesis of CeO2/PVDC hybrid latexes for use as waterborne barrier films with improved UV-stability

Style APA, Harvard, Vancouver, ISO itp.

20

Baina, Jamal. "Codage hybride adaptatif d'images en vue de la transmission à bas débit : logiciel et matériel". Metz, 1992. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1992/Baina.Jamal.SMZ924.pdf.

Pełny tekst źródła

Streszczenie:

Les techniques de codage d'image en vue de la transmission à bas débit sont nombreuses et se différencient par leurs performances et par leurs algorithmes. Le procédé de codage que nous avons élaboré se caractérise par l'application de la transformée en cosinus discrète (TCD) suivie par une quantification vectorielle. Cette méthode exploite une classification des formes perceptibles dans l'espace transformé. Un exemple de système de codage-décodage est présenté dans ce mémoire. Il est conçu autour de processeur parallèle transputer et de processeur du signal
Image coding methods are used for low rate transmission. The difference between these methods lies in compression ratio and image subjective quality. We developed a new image coding method based on a visual classifier. A visual vector quantization is applied on the discret cosine transform coefficients, using the correspondance between the image domain and transform domain. A parallel coding system is described here. It's based on digital signal processors and transputers

Style APA, Harvard, Vancouver, ISO itp.

21

Bacciaglia, Antonio. "Design and Development of a Propulsion System for a Water-Air Unmanned Vehicle". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

Znajdź pełny tekst źródła

Streszczenie:

This work aims to contribute on the design of a Bimodal Unmanned Underwater and Air System (BUUAS). This research project will first present background informations of current hybrid UAV concepts with a focus on the different types of propulsion mechanisms used in air/water transition. Then a brief description of BUUAS will lead to requirements for the transition mechanism that this work aims to develop. After a section dedicated to the description of a short-impulse thruster layout, theoretical and experimental approaches are used to determine the amount of thrust generated. As second design step, a simplified UAV version is used to test the transition phase using the designed thruster. Finally, a section is dedicated to a design layout description with the thruster and an optimized propeller. Future work is proposed to continue in the development of this project, with a short description of folding wing and propulsion system integration concepts.

Style APA, Harvard, Vancouver, ISO itp.

22

Johansson, Åke, i Joel Wikner. "Learning-Based Motion Planning and Control of a UGV With Unknown and Changing Dynamics". Thesis, Linköpings universitet, Reglerteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176923.

Pełny tekst źródła

Streszczenie:

Research about unmanned ground vehicles (UGVs) has received an increased amount of attention in recent years, partly due to the many applications of UGVs in areas where it is inconvenient or impossible to have human operators, such as in mines or urban search and rescue. Two closely linked problems that arise when developing such vehicles are motion planning and control of the UGV. This thesis explores these subjects for a UGV with an unknown, and possibly time-variant, dynamical model. A framework is developed that includes three components: a machine learning algorithm to estimate the unknown dynamical model of the UGV, a motion planner that plans a feasible path for the vehicle and a controller making the UGV follow the planned path. The motion planner used in the framework is a lattice-based planner based on input sampling. It uses a dynamical model of the UGV together with motion primitives, defined as a sequence of states and control signals, which are concatenated online in order to plan a feasible path between states. Furthermore, the controller that makes the vehicle follow this path is a model predictive control (MPC) controller, capable of taking the time-varying dynamics of the UGV into account as well as imposing constraints on the states and control signals. Since the dynamical model is unknown, the machine learning algorithm Bayesian linear regression (BLR) is used to continuously estimate the model parameters online during a run. The parameter estimates are then used by the MPC controller and the motion planner in order to improve the performance of the UGV. The performance of the proposed motion planning and control framework is evaluated by conducting a series of experiments in a simulation study. Two different simulation environments, containing obstacles, are used in the framework to simulate the UGV, where the performance measures considered are the deviation from the planned path, the average velocity of the UGV and the time to plan the path. The simulations are either performed with a time-invariant model, or a model where the parameters change during the run. The results show that the performance is improved when combining the motion planner and the MPC controller with the estimated model parameters from the BLR algorithm. With an improved model, the vehicle is capable of maintaining a higher average velocity, meaning that the plan can be executed faster. Furthermore, it can also track the path more precisely compared to when using a less accurate model, which is crucial in an environment with many obstacles. Finally, the use of the BLR algorithm to continuously estimate the model parameters allows the vehicle to adapt to changes in its model. This makes it possible for the UGV to stay operational in cases of, e.g., actuator malfunctions.

Style APA, Harvard, Vancouver, ISO itp.

23

Nebioglu, Ahmet. "NETWORK FORMATION AND THERMO-MECHANICAL PROPERTIES OF PHOTO-CURING HYBRID COATINGS". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145166725.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

24

Svoboda, Tomáš. "Příprava a vlastnosti organokřemičitých pojiv pro nanočásticové vrstvy oxidu titaničitého". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316147.

Pełny tekst źródła

Streszczenie:

This diploma thesis deals with the synthesis of an organosilica polymer which could be used as a binder for titanium dioxide photocatalytic layers. The main reason for incorporating the binder into the photocatalytic layers is not only the improving of the mechanical properties, but above all, the binder could help with production of low-temperature photocatalytic layers, that could be applied to heat-sensitive materials such as plastic materials. This could create layers on flexible materials that could be easily made into any shape. The work focuses on the synthesis of organosilica polymer from the organosilica precursor and subsequent characterization of the binder. Surface tension, viscosity, density, XRD, thermal analysis of silica binder solutions was performed. Titanium dioxide compositions with this binder were prepared, then they were printed and the layers were treated with UV and plasma. Treated layers were examined by FT-IR and a voltamperometric characterization was performed.

Style APA, Harvard, Vancouver, ISO itp.

25

Laurent, Adèle. "Etude de phénomènes électroniques de macromolécules à l'aide de méthodes hybrides QM-MM". Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10075/document.

Pełny tekst źródła

Streszczenie:

Les méthodes hybrides alliant la mécanique quantique et la mécanique moléculaire (QM/MM) sont des outils adéquats pour traiter des systèmes biologiques. Les phénomènes électroniques souvent étudiés sur des petites molécules ont, dès lors pu être envisagés dans des environnements macromoléculaires. Ce travail explore trois phénomènes électroniques en présence d'un environnement protéique: l'absorption, la capture électronique et les ionisations de coeur. Nous avons employé les derniers développements de la méthode QM/MM {Local Self-Consistent Field} (LSCF) pour traiter la jonction covalente entre la partie QM et la partie MM ainsi que le couplage QM/MM avec le PCM. En premier lieu, nous nous sommes focalisés sur les spectres d'absorption de chromophores présents dans des macromolécules. Nous avons mis au point un couplage entre les méthodes LSCF/MM et PCM pour prendre en compte la polarisation électronique de l'environnement suite à l'absorption d'un photon par le chromophore. Ce modèle, le LSCF/MM\string:ERS, a été testé et validé sur le spectre d'absorption du complexe de squaraine-tétralactame. Une étude plus poussée a ensuite été réalisée sur une protéine fluorescente en décomposant la longueur d'onde d'absorption maximale en trois contributions physiques. Les effets de la substitution du chromophore ont aussi été évalués. Dans une seconde partie, nous avons étudié la capture électronique par un cyclotide contenant trois ponts disulfures, qui, après irradiation, forment des demi-liaisons caractéristiques (2c-3e). La dernière partie est consacrée à la validation de l'approche de la projection asymptotique. Elle a été réalisée dans le cadre d'une étude sur les ionisations de coeur d'un ensemble de molécules pour, par la suite, étudier les ionisations de coeur de la glycine présentes dans des systèmes de plus en plus complexes jusqu'à la Sérum-Albumine Humaine
Hybrid methods that combine quantum mechanics and molecular mechanics (QM/MM) provide a near-ideal treatment of biological system reactivity and spectroscopy. Many electronic phenomena often studied on small systems can be now forseen in macromolecular surroundings. This work considers the treatment with QM/MM tools of three electronic phenomena in biosystem: absoprtion, electronic attachment and core ionization. Latest developments of the Local Self-Consistent Field formalism (LSCF) have been used to treat delicate covalent junctions between the QM part and the MM part and the coupling of QM/MM and PCM methods. Firstly we have focussed on absorption spectra of chromophores embedded in macromolecules. The combined LSCF/MM and PCM approach have been employed to account for the electronic polarization when the chromophore absorbs one photon. This new method, called LSCF/MM\string:ERS has been tested and validated with the study of the absorption spectra on the squarain-tetralactam complex. Then, we have considered a fluorescent protein and decomposed the maximum absorption wavelength into several physical contributions. We have also analyzed the substitution effect of the chromophore. Secondly, the electronic capture have been studied on a cyclotide containing three disulfide bonds, which forms caracteristic hemi-bond (2c-3e) after irradiation. The last electronic phenomena studied is the core ionization tackled within the framework of the asymptotic projection approach. The latter has been implemented, then tested and validated on a set of molecules. This method have been employed to analyze the specific core ionization of glycine-containing systemes of increasing complexity, up to the Human Serum Albumin

Style APA, Harvard, Vancouver, ISO itp.

26

Hasheminasab, S. Abed. "Bismaleimide Methacrylated Polyimide-Polyester Hybrid UV-Curable Powder Coating". University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1586906287945286.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

27

Kunst, Sandra Raquel. "Filmes híbridos modificados com agentes flexibilizantes para uso como revestimento barreira e como pré-tratamento de folha de flandres para aplicação de tinta UV". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/131364.

Pełny tekst źródła

Streszczenie:

Um dos principais problemas da folha de flandres utilizada no setor de embalagens é a adesão dos revestimentos UV sobre o substrato devido à presença de óxidos na superfície. Dessa forma, o emprego de pré-tratamentos superficiais se faz necessário, e o uso de revestimentos híbridos tem sido proposto para melhorar a aderência e a resistência à corrosão. Contudo, esses revestimentos tendem a serem frágeis e não suportam deformação mecânica. No presente trabalho, os filmes híbridos foram depositados sobre a folha de flandres a fim de avaliar o seu desempenho como revestimento protetor e como pré-tratamento para posterior aplicação do revestimento UV. Visando melhorar o efeito barreira, as folhas de flandres foram revestidas com um filme híbrido obtido a partir de um sol constituído pelos precursores: 3-(trimetoxisililpropil)metacrilato (TMSM) e tetraetoxisilano (TEOS) e Ce(NO3)3 0,01M com adição do plastificante di-isodecil adipato (DIDA) em diferentes concentrações: (0,5, 1, 2 e 4%). Utilizou-se o processo de dip-coating com velocidade de retirada de 10 cm.min-1, com aplicação em monocamada e bicamada, e curados por cura térmica empregando-se duas diferentes temperaturas de cura, 60 °C e 90 °C. Com o objetivo de analisar um pré-tratamento para posterior aplicação do revestimento UV, as folhas de flandres foram revestidas com um filme híbrido obtido a partir de um sol com a mesma formulação citada, substituindo o plastificante DIDA pelo flexibilizante polietilenoglicol (PEG) em diferentes concentrações: (20, 40, 60 e 80 g.L-1). Os filmes foram obtidos e curados conforme descrito anteriormente, além disso, após o pré-tratamento com filme híbrido, a folha de flandres foi submetida ao processo de pintura com tinta uretânica alifática acrilada curada por radiação ultravioleta (UV). Foram empregadas como técnicas para caracterização quanto ao comportamento eletroquímico: monitoramento do potencial de circuito aberto, curvas de polarização potenciodinâmicas, medidas de impedância eletroquímica e svet. O comportamento físico-químico dos filmes foi avaliado por ângulo de contato, termogravimetria, espectroscopia de infravermelho e ressonância magnética nuclear. A resistência ao desgaste foi avaliada pela técnica de esfera sobre plano. Os sistemas de pintura curada por radição ultravioleta foram analisados quanto à adesão, flexibilidade e molhabilidade. Os resultados obtidos, mostraram que a adição de 2% do plastificante di-isodecil adipato melhorou a resistência à corrosão e a cura a 90 °C e com aplicação da bicamada otimizou o efeito barreira do filme. Adição de PEG na concentração de 20 g.L-1 contribuiu para melhorar a flexibilidade do filme retardando a cinética da reação de reticulação e consequentemente evitando a formação de fissuras. Nesta concentração, e curado a 60 °C, o filme melhorou a resistência mecânica para os sistemas com pós-tratamento em tinta UV.
One of the main problems of the tinplate for the packaging sector is the coating adherence of UV coatings on the substrate, due to the presence of oxides on the surface. Thus, it makes necessary the use of surface pretreatments, and the use of hybrid coatings has been proposed to improve the adherence and corrosion resistance. However, these hybrid films tend to be fragile and do not hold on mechanical deformation. In this work, the tinplate was coated with hybrid films aiming to evaluate its performance as protective coating and as pre-treatment for further UV coating application. In order to improve the barrier effect, the tinplate were coated with a hybrid film obtained from a sol constituted by the precursors 3-(trimethoxysilyl)propyl methacrylate (TMSM) and tetraethoxysilane (TEOS), 0.01 mol.L-1 cerium nitrate (Ce(NO3)3) and diisodecyl adipate (DIDA) in different concentrations (0.5, 1, 2 and 4%) as plasticizer. Dip-coating was the process for applying the films with removal rate of 10 cm.min-1. The films were applied in one or two layers and, then, thermally cured at 60 °C or 90 °C. As a pretreatment for further UV coating, the tinplate were coated with a hybrid film with the aforementioned formulation, but replacing the plasticizer DIDA for polyethylene glycol (PEG) in different concentrations (20, 40, 60 e 80 g.L-1). The films were obtained and cured through the same dip-coating process and, after, the samples were painted with aliphatic acrylic urethane coating with ultraviolet radiation curing. The characterization techniques for electrochemical behavior were open circuit potential monitoring, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). The physicochemical behavior of the films was evaluated by contact angle measurement, thermogravimetric analysis, infrared spectroscopy and nuclear magnetic resonance. Wear resistance was evaluated by using a ball-on-plate test. The systems with UV-radiation-cured ink were analyzed regarding adherence, flexibility and wettability. Results showed that adding 2% of DIDA plasticizer improved the corrosion resistance and that curing a bilayer film at 90 °C optimizes the film barrier effect. Adding PEG in a concentration of 20 g.L-1 improved the flexibility of the film, making the cross-linking reaction kinetics slower and, in consequence, avoided cracks. With this concentration and curing at 60 °C, the film had better mechanical resistance for systems post-treated with UV ink.

Style APA, Harvard, Vancouver, ISO itp.

28

Chakraborty, Ruby. "Development of Novel Cycloaliphatic Siloxanes for Thermal and UV-curable Applications". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1207682542.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

29

Manoel, Diego da Silva [UNESP]. "Materiais híbridos de sílica/orgânico dopados com rodamina-B: propriedades luminescentes e emissão laser randômico". Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/148710.

Pełny tekst źródła

Streszczenie:

Submitted by Diego da Silva Manoel null (diegosma@rc.unesp.br) on 2017-02-05T16:40:20Z No. of bitstreams: 1 Dissertação Diego.pdf: 1793320 bytes, checksum: ba0a17055ebb3486b214146535165ef9 (MD5)
Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-02-06T18:25:08Z (GMT) No. of bitstreams: 1 manoel_ds_me_rcla.pdf: 1793320 bytes, checksum: ba0a17055ebb3486b214146535165ef9 (MD5)
Made available in DSpace on 2017-02-06T18:25:08Z (GMT). No. of bitstreams: 1 manoel_ds_me_rcla.pdf: 1793320 bytes, checksum: ba0a17055ebb3486b214146535165ef9 (MD5) Previous issue date: 2017-01-17
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O processo sol-gel permite a produção de materiais Híbridos Orgânicos/Inorgânicos para aplicações em óptica e fotônica. Materiais Híbridos de Sílica/orgânico unem propriedades da Sílica e dos polímeros orgânicos e permitem a incorporação de diversas moléculas orgânicas na matriz, possibilitando a obtenção de materiais fotoativos avançados. Destas moléculas destacam-se os corantes lasers, como a Rodamina-B, que possui comprimento de onda de emissão bem definido e alta eficiência quântica. Neste trabalho preparamos materiais híbridos de sílica/orgânico via processo sol-gel utilizando como precursores os alcóxidos de silício 3-glicidoxipropiltrimetoxisilano (GPTS) e tetraetilortosilicato (TEOS). Amostras ainda na fase de sol foram dopadas com Rodamina-B em concentrações variando de 0,01 a 5 mmol/L. A fluorescência das amostras foi caracterizada mostrando dependência entre as características da emissão e a concentração de dopante. Os espectros de fluorescência sofrem um deslocamento para a região do vermelho com o aumento da concentração do dopante, enquanto a intensidade de emissão apresenta maior valor para a amostra com concentração de 0,5 mmol/L. Também foram determinados os coeficientes de absorção óptica, que apresentaram comportamento linear com a concentração. A partir das amostras (sol) foram produzidos xerogéis com concentrações de Rodamina-B de 0,0386 a 19,3 mmol/L. Os espectros de fluorescência destes xerogéis também apresentaram deslocamento para a região do vermelho para maiores concentrações de dopante, a intensidade de emissão é máxima para o xerogel com concentração de 6,56 mmol/L. Os coeficientes de absorção óptica dos xerogéis apresentaram um comportamento linear com a concentração de dopante. O xerogel com concentração de 19,3 mmol/L de Rodamina-B apresentou emissão de laser randômico quando excitado com laser pulsado (532 nm, 8ns), fenômeno caracterizado por um estreitamento da banda de emissão devido a dímeros da Rodamina-B em 630 nm. Microscopia eletrônica de transmissão revelou a formação de partículas de Sílica com diâmetro médio de 6,3 nm distribuídas na matriz sólida. Estes resultados são de grande interesse para aplicações em fotônica.
Organic-Inorganic Hybrid Materials prepared by sol-gel process have applications in different areas such as optics and photonics. Silica/organic hybrid materials combine the properties from the silica and the organic polymers and can be doped with organic molecules with different optical properties, allowing preparation of advanced photoactive materials. In the wide range of photoactive organic materials one of interest is the Rhodamine-B, a laser dye which presents tunable emission and high quantum yield. In this work we have produced hybrid silica/organic samples derived from 3-glycidoxypropyltrimethoxysilane (GPTS) and tetraethylorthosilicate (TEOS) by sol-gel process. Silica/organic sols were doped with Rhodamine-B concentrations ranging from 0.01 to 5 mmol/L. The fluorescence spectra of the samples were characterized and a relationship between emission characteristics and dopant concentration has been observed. A red shift in the wavelength emission was observed, as the dopant concentration increased and the maximum emission intensity was achieved for the sample with concentration of 0.5mmol/L. Were determined the optical absorption coefficients that showed a linear relation with the concentration. The sol samples were dried and xerogels were obtained and the new concentrations of Rhodamine-B in the solid matrix were determined, ranging from 0.0386 to 19.3 mmol/L. The fluorescence spectra of the xerogels were characterized, showing a red shift as the dopant concentration increased and the maximum emission intensity was achieved for the xerogel with concentration of 6.56 mmol/L. The optical absorption coefficients of these xerogels showed a linear behavior with the dopant concentration. Random laser action for the xerogel with concentration of 19.3 mmol/L was measured using an pulsed laser (532 nm, 8ns), and characterized by a narrowing emission of the Rhodamine-B dimmers emission at 630 nm. Transmission electron microscopy revealed silica particles with 6.3 nm average diameter in the solid matrix. These results are very important for applications in photonics.

Style APA, Harvard, Vancouver, ISO itp.

30

Fayon, Pierre. "Développement d’un schéma de couplage QM/MM (Quantum Mechanic / Molecular Mechanic) pour les états excités localisés dans les matériaux hybrides organique-inorganiques". Thesis, Pau, 2011. http://www.theses.fr/2011PAUU3018/document.

Pełny tekst źródła

Streszczenie:

Ces dernières années, la mise au point de matériaux hybrides organique-inorganiques a fait l’objet d’un intérêt grandissant dans le domaine de la chimie verte. Les matériaux hybrides a base de silice fonctionnalisée par des molécules organiques possèdent des propriétés modulables, permettant leur application dans plusieurs domaines (photochimie, médecine, dépollution . . .). D’un point de vue théorique, le challenge d’une telle étude résulte dans la détermination des propriétés d’optiques. En effet, la taille de ces systèmes ne permet pas un traitement de ces derniers d’un point de vue strictement quantique. L’enjeu de ce travail de recherche est le développement d’un programme qm/mm/tddft (Quantum Mechanic/Molecular Mechanic/ Time Dependant Density Functional Theory), pour le calcul des états électroniques excités localisés dans les solides, avec une applicationparticulière au domaine UV-visible dans les matériaux hybrides organique-inorganiques.Dans la pratique, l’intégration des équations classiques du mouvement de tous les noyaux est effectuée par le programme de dynamique moléculaire dl poly, tandis que les contributions aux forces issues des atomes dans la partie de la simulation quantique sont évaluées par le code siesta en utilisant la méthode dft (Density Functional Theory). Les spectres électroniques seront calculés avec un nouveau code de tddft (Time Dependant Density Fuctional Theory) développé pour ce projet, dans lequel l’utilisation d’une base de produits dominants accélère le calcul de façon notable
Last years, the development of organic-inorganic hybrid materials has been a growing interest in the field of green chemistry. Hybrid materials based on silica functionalized with organic molecules have flexible properties, allowing their application in several fields (photochemistry, medicine, ...). From a theoretical point of view, the challenge of such a study results in determination of the optical properties. Indeed, the size of the system does not allow treatment with a purely quantum theory. The aim of this research is to develop a qm/mm/tddft (Quantum Mechanic / Molecular Mechanic / Time Dependent Density Functional Theory) code to calculate the excited electronic states localized in solids, with a particular application for the UV-visible region in organic-inorganic hybrid materials. In practice, the integration of classical equations of motion of all the nuclei are made by the molecular dynamics program dl poly, while contributions from the forces in the quantum simulation are evaluated by using the code siesta with the dft (Density Functional Theory) method . The electronic spectra are calculated with a new tddft code developed for this project, in which the use of dominants products accelerates the calculation significantly

Style APA, Harvard, Vancouver, ISO itp.

31

Jesus, Agnaldo Oliveira de. "As bibliotecas nos polos de apoio presencial de educação à distância no estado da Bahia". Instituto de Ciência da Informação, 2015. http://repositorio.ufba.br/ri/handle/ri/18686.

Pełny tekst źródła

Streszczenie:

Submitted by Valdinei Souza (neisouza@hotmail.com) on 2015-10-09T21:03:43Z No. of bitstreams: 1 AS BIBLIOTECAS NOS POLOS DE APOIO PRESENCIAL DE EDUCAÇÃO A DISTÂNCIA NO ESTADO DA BAHIA.pdf: 1369770 bytes, checksum: c83e9b974c6a08376ad328be09056310 (MD5)
Approved for entry into archive by Urania Araujo (urania@ufba.br) on 2016-03-04T21:23:36Z (GMT) No. of bitstreams: 1 AS BIBLIOTECAS NOS POLOS DE APOIO PRESENCIAL DE EDUCAÇÃO A DISTÂNCIA NO ESTADO DA BAHIA.pdf: 1369770 bytes, checksum: c83e9b974c6a08376ad328be09056310 (MD5)
Made available in DSpace on 2016-03-04T21:23:36Z (GMT). No. of bitstreams: 1 AS BIBLIOTECAS NOS POLOS DE APOIO PRESENCIAL DE EDUCAÇÃO A DISTÂNCIA NO ESTADO DA BAHIA.pdf: 1369770 bytes, checksum: c83e9b974c6a08376ad328be09056310 (MD5)
O desenvolvimento de novas práticas de produção e de serviços baseados no uso da informação e do conhecimento caracteriza a sociedade contemporânea. Neste contexto, a Educação a Distância (EaD) surge como meio adequado para propiciar nova forma de ensino e aprendizagem, na qual os agentes envolvidos no processo podem estar separados no tempo e no espaço. Esta modalidade de educação carece de uma biblioteca híbrida, na qual os agentes envolvidos no processo de ensino-aprendizagem tenham acesso à informação para subsidiar o desenvolvimento das atividades acadêmicas. A pesquisa tem como objetivo geral a n a l i s a r de que forma as bibliotecas dos polos de apoio presencial de EaD da Universidade Aberta do Brasil (UAB), na Bahia, atendem os discentes e disponibilizam materiais informacionais para os cursos na modalidade EaD. O percurso metodológico resultou em uma pesquisa do tipo exploratória e descritiva; a abordagem adotada teve por base a teoria da complexidade, a partir das ideias do filósofo Edgar Morin, que serviu de lastro para o entendimento dos fenômenos relacionados à modalidade de EaD. O procedimento adotado foi o de estudos de casos múltiplos. As técnicas adotadas foram a observação direta extensiva e questionário eletrônico. A análise dos dados advém dos questionários respondidos pelos coordenadores do polo de apoio presencial. Entre os aspectos problemáticos observados estão a falta de bibliotecário no quadro profissional dos polos, as bibliografias básica e complementar em sua maioria no formato impresso, não inclusão de recursos tecnológicos de redes sociais no ambiente da biblioteca, falta de cooperação das bibliotecas das universidades mantenedoras dos cursos no polo. Entre os aspectos positivos, destacamos a presença de todas as instituições públicas de ensino superior de origem baiana oferecendo cursos na modalidade EaD, além das instituições de ensino superior oriundas de outros estados e Distrito Federal: todos os polos demonstraram que possuem biblioteca na infraestrutura. Diante das evidencias apontadas no resultado da pesquisa tornou-se possível concluir que a biblioteca de apoio presencial da EaD disponibiliza produtos e serviços focados nas necessidades dos discentes presenciais.
ABSTRACT The development of new practices of production and services based on the use of information and knowledge characterizes contemporary society. In this context, the Distance Education (DE) emerges as an appropriate means to provide new ways of teaching and learning. The agents involved in the process can actually be separated in time and space. This kind of education lacks a hybrid library, the agents involved in teaching and learning processes have access to information in order to support academic activities. The research has as its main objective to analyze how the presential libraries (from the support poles of DE at Universidade Aberta do Brasil – UAB), in Bahia, serve the students and provide informational materials for DE courses. Methodologically, this is an exploratory, descriptive research; the adopted approach was based on the theory of complexity, from the philosopher Edgar Morin, which served as basis for understanding the phenomena related to DE issue. The adopted procedures are those which characterize multiple case studies. The adopted techniques were extensive direct observation and electronic questionnaire. The data analysis was done from the answered questionnaires by presential support coordinators. Among some problematic aspects are: the absence of a librarian in the poles staff; the basic and supplementary bibliographies mostly in print format; non-inclusion of social networks technological resources in the library; lack of cooperation among the university sponsor libraries.. Among positive aspects, we highlight the presence of all higher education public institutions from Bahia offering DE courses, in addition to other higher education institutions from different Union States and the Union District Capital: the poles, all of them, have a library in its infrastructure. Facing the research results and its evidences it is possible to conclude that DE presential support libraries have products and services focused on presential student needs.

Style APA, Harvard, Vancouver, ISO itp.

32

Narayanan, Nair Maya. "Functionalization of epitaxial graphene by metal intercalation and molecules". Phd thesis, Université de Haute Alsace - Mulhouse, 2013. http://tel.archives-ouvertes.fr/tel-01064523.

Pełny tekst źródła

Streszczenie:

In this thesis, we have explored the possibilities to realize a Graphene Based Hybrid structures (GBHs) by the functionalization of a graphene layer on both sides. The first chapter gives a general introduction about graphene and a literature review of different metal intercalations on graphene. The second chapter explains the experimental techniques used in this work. In chapter 3, we studied the functionalization of epitaxial graphene on SiC(0001) by gold intercalation. With the help of Scanning Tunneling Microscopy, we have evidenced and characterized different intercalation modes such as the formation of aggregates of individual gold atoms and the formation of a continuous gold layer between the top graphene and the buffer layer. The free standing nature of the intercalated gold atoms was examined by differential charge density plot, projected density of states calculations and further by X-ray photoelectron spectroscopy. The band structure modification of graphene due to these intercalated gold atoms was evidenced by Angle-resolved photoemission spectroscopy, which reveals a strong Van Hove extension and an increase of the Fermi velocity. Extend to this research, to obtain an extended Van Hove singularity usually observed in highly doped graphene; we studied highly electron donor molecules, TetraThioFullvalene (TTF) on pristine and gold intercalated graphene and on graphite (chapter 4). The dependence of charge transfer of these molecules with their conformation and the reactivity of photochromic with conjugated molecules on graphene were also discussed. To understand the structural properties of these molecules photophysical measurements were performed in chapter 5.

Style APA, Harvard, Vancouver, ISO itp.

33

Mhiri, Akram. "Elaborations, caractérisations et études spectroscopiques des composés hybrides organiques-inorganiques R2SnBr6 avec R=N(CH3)4 et R=N(CH3-CH2)4". Thesis, Le Mans, 2020. http://www.theses.fr/2020LEMA1032.

Pełny tekst źródła

Streszczenie:

Ce travail s'est inscrit dans le cadre d’un projet de recherche qui vise à synthétiser et caractériser de nouveaux matériaux hybrides organiques-inorganiques pouvant être utilisés dans la fabrication de cellules photovoltaïques, mais avec des éléments moins polluants que les composés actuellement proposés. Pour cela nous avons élaboré et étudié deux nouveaux composés à base d'étain : le bis tétraméthylammonium hexabromostannate ([N(CH₃)₄]₂SnBr₆), et le bis-tétraéthylammonium hexabromostannate ([CH₃-CH₂]₄SnBr₆). Les études expérimentales sont basées sur des analyses thermiques (ATD, DSC, ATG), la spectrométrie par dispersion en énergie (EDX), la diffraction de rayons X sur poudre et sur monocristal, les spectrométries vibrationnelles (infrarouge et Raman), la spectrométrie d’impédance complexe et la spectrométrie UV-Visible.Il est apparu que [N(CH₃)₄]₂SnBr₆ est de symétrie cubique du type K₂PtCl₆. Il est constitué d'octaèdres SnBr₆²- non connectés entre eux, séparés par des tétraméthylammoniums, pouvant être considéré comme dérivé d'une structure pérovskite dans laquelle la moitié des sites de symétrie octaédriques sont occupés par des SnBr₆²- et la moitié par des lacunes (structure pérovskite 0D). Cet arrangement laisse ainsi de très larges volumes libres de tout atome, et nous avons même montré qu'il présente des canaux ouverts infinis de large section (0,5 nm de diamètre), pouvant ainsi être considéré comme poreux. Les analyses vibrationnelles couplées à des calculs ab-initio sur l'octaèdre SnBr₆²- et l'ion tétraméthylammonium (TMA+) ont permis d'expliquer sans ambiguïté les spectres et de conclure à l'existence de désordre local. Les signaux infrarouges, Raman et EDX suggèrent aussi la présence d’OH- ou d’'eau, probablement en relation avec la structure lacunaire. Il a été montré que le composé subit une transition de phase réversible à plus haute température (vers 100°C). Les études vibrationnelles confirment la transition de phase, de même que les études des propriétés diélectriques. Le gap (2,31 eV) est proche de la largeur de la bande interdite 2,7 eV du semi-conducteur Cs₂SnBr₆ utilisé dans les cellules solaires.Le bis-tétraéthylammonium hexabromostannate [CH₃-CH₂]₄SnBr₆ à température ambiante présente une structure (rhomboédrique) composée également d'octaèdres SnBr₆²- non connectés, mais d'arrangement structural compact, contrairement au composé au TMA. Son étude en température révèle deux transitions réversibles mais avec fortes hystérésis à 262K/239K et à 362K/307K (chauffage/refroidissement). Son énergie de gap est égale à 2,51 eV
This work is part of a research project that aims to synthesize and characterize new organic-inorganic hybrid materials that can be used in the manufacture of photovoltaic cells, but with less polluting elements than the compounds currently proposed. For this we have developed and studied two new compounds based on tin : bis tetramethylammonium hexabromostannate ([N(CH₃)₄]₂SnBr₆), and bis-tetraethylammonium hexabromostannate ([CH₃-CH₂]₄SnBr₆). The experimental studies are based on thermal measurements (ATD, DSC, ATG), energy dispersion spectrometry (EDX), powder and single crystal X-ray diffraction, vibrational spectrometries (infrared and Raman), complex impedance spectrometry, and UV-Visible spectrometry.It appeared that [N(CH₃)₄]₂SnBr₆ is of cubic symmetry of the K₂PtCl₆ type. It consists of unconnected SnBr₆²- octahedra, separated by tetramethylammoniums, which can be considered to be derived from a perovskite structure in which half of the sites of octahedral symmetry are occupied by SnBr₆²- and half by vacancies (perovskite structure 0D). This arrangement thus leaves very large volumes free of any atom, and we have even shown that it has infinite open channels of large section (0,5 nm in diameter) ; it can thus be considered as a porous material. The vibrational analyzes coupled with ab-initio calculations on the SnBr₆²- octahedron and the tetramethylammonium ion (TMA+) made it possible to unambiguously explain the spectra and to conclude to the existence of local disorder. Infrared, Raman and EDX signals also suggest the presence of OH- or water, probably related to the porous structure. It has been shown that the compound undergoes a reversible phase transition at a higher temperature (around 100°C). Vibrational studies confirm the phase transition, as do studies of dielectric properties. The gap (2,31 eV) is close to the width of the 2,7 eV forbidden band of the Cs₂SnBr₆ semiconductor used in solar cells.Bis-tetraethylammonium hexabromostannate [CH₃-CH₂]₄SnBr₆ at room temperature exhibits a (rhombohedral) structure also composed of non-connected SnBr₆²- octahedra, but of compact structural arrangement, unlike the compound with TMA. Its temperature study reveals two reversible transitions but with strong hysteresis at 262K / 239K and at 362K / 307K (heating / cooling). Its gap energy is equal to 2,51 eV

Style APA, Harvard, Vancouver, ISO itp.

34

Scarpellini, M. "ADVANCED MATERIALS: PREPARATION, STUDY AND OPTIMIZATION OF THIN FILM FOR OPTO-ELECTRONIC DEVICE". Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150151.

Pełny tekst źródła

Streszczenie:

The term “optoelectronic devices” is by now used for devices in which both electrons and photons are essential for their operation, as a natural evolution from the definitions of electronic devices that involved only electrons and holes in their operation and of photonic devices that involved only photons in their operation. One of the new lighting technologies which emerged within the past two decades and has the potential of becoming more energy-efficient then the existing light sources, is the Solid State Lighting technology of Organic Light Emitting Diodes (OLEDs). In general, the basic OLED structure consists of a stack of fluorescent organic layers sandwiched between a transparent conducting anode and metallic cathode. When an appropriate current is applied to the device, holes are injected from the anode and electrons from the cathode; some of the recombination events between the holes and electrons result in electroluminescence (EL). The first part of this PhD Thesis surveyed different aspect in OLED technology that are currently under debate. In particular chapter 2 is devoted to the study, preparation and optimization of thin films between the organic hole transport layer and the anode surface while chapter 3 deals with the synthesis of trifluorene compound, with methoxy substituents, as possible UV-blue emitter. The second part of this PhD work is dedicated to the synthesis and study of new materials with interesting emissive and second order NLO properties. In particular pyrene based chromophores are investigated in chapter 4, while chapter 5 deals with the synthesis of organic-inorganic perylene-POSS hybrids with enhanced emissive properties.

Style APA, Harvard, Vancouver, ISO itp.

35

Candel, Busquets Inmaculada. "Functional silica materials for controlled release, sensing and elimination of target molecules". Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/39101.

Pełny tekst źródła

Streszczenie:

La presente tesis doctoral titulada “Materiales de sílice funcionales para la liberación controlada, detección y eliminación de moléculas de interés” se centra en el diseño y desarrollo de materiales híbridos orgánico-inorgánicos mediante la aplicación de los conceptos de Química Supramolecular. Durante el desarrollo de la presente tesis doctoral se han preparado y caracterizado diferentes materiales de base silícea para distintas aplicaciones. La primera parte de la tesis se centra en el desarrollo de materiales de base silícea capaces de variar su comportamiento fluorescente en función de la presencia o ausencia de un cierto analito en el medio. Estos materiales emplean como soporte nanopartículas de sílice que se funcionalizan superficialmente con dos unidades diferentes, una coordinante y una indicadora (un fluoróforo). La interacción del analito de interés (en nuestro caso aniones) con la unidad coordinante modificará las propiedades emisivas del fluoróforo. Así, se han preparado dos materiales en los cuales el grupo fluorescente es rodamina mientras que el grupo coordinante es un imidazolato o una sal de guanidinio respectivamente. Una vez caracterizados ambos materiales se estudió su comportamiento frente a diferentes especies aniónicas a diferentes concentraciones resultando selectivos a la presencia de benzoato (el material funcionalizado con imidazolatos), dihidrógeno fosfato e hidrógeno sulfato (el material funcionalizado con sales de guanidinio). El tercer capítulo de la tesis se centra en la aplicación de materiales híbridos orgánico-inorgánicos para la detección y eliminación de especies altamente tóxicas como son los agentes neurotóxicos. Estos son compuestos organofosforados capaces de causar graves lesiones en el sistema nervioso central. En una primera aproximación se emplea el concepto de puerta molecular para la detección de agentes neurotóxicos. Para ello, se utiliza como soporte inorgánico un material mesoporoso de sílice (MCM-41) cuyos poros se cargan con un colorante que actúa de indicador mientras que la superficie externa del mismo se funcionaliza con una molécula capaz de reaccionar con dichos agentes neurotóxicos. Dicha molécula es capaz de interaccionar entre sí (mediante enlaces de hidrógeno) formando una red que mantiene bloqueada la salida de los poros. En presencia de DCP (dietilclorofosfato, un simulante de agente neurotóxico), y después de que este reaccione con dicha molécula, se produce una reorganización espacial que permite la liberación del colorante. De este modo, la presencia de los agentes neurotóxicos está señalizada mediante un cambio de color. En una segunda aproximación se aborda el uso de soportes inorgánicos de tipo MCM-41 como materiales para la eliminación de agentes neurotóxicos. Para ello se modificaron químicamente las superficies de estos materiales silíceos mediante tratamiento con distintas bases. Como consecuencia de este tratamiento básico los silanoles de la superficie se desprotonan dando lugar a los correspondientes silanolatos (nucleófilos fuertes). Estos silanolatos son capaces de reaccionar con los agentes neurotóxicos descomponiéndolos y favoreciendo su eliminación de un medio contaminado. Por último, se estudia la aplicación de materiales híbridos orgánico-inorgánicos funcionalizados con puertas moleculares en aplicaciones de liberación controlada, concretamente, en liberación controlada intracelular de fármacos de interés. El material híbrido consta de un soporte de sílice mesoporosa cuyos poros se cargan con un compuesto citotóxico (camptotecina) y su superficie externa se funcionaliza con una gluconamida. La presencia de una monocapa densa de gluconamidas por el exterior del material inhibe la liberación del compuesto citotóxico. Al añadir enzimas con capacidad para hidrolizar enlaces amida (amidasa y pronasa) se produce la liberación de la camptotecina. El correcto funcionamiento del material se comprobó in vitro e in vivo (en células HeLa).
Candel Busquets, I. (2014). Functional silica materials for controlled release, sensing and elimination of target molecules [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/39101
TESIS

Style APA, Harvard, Vancouver, ISO itp.

36

Wissmann, Paul J. "Simultaneous approach to model building and process design using experimental design application to chemical vapor deposition /". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26543.

Pełny tekst źródła

Streszczenie:

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Grover, Martha; Committee Member: Garmestani, Hamid; Committee Member: Hess, Dennis; Committee Member: McDowell, David; Committee Member: Nenes, Athanasios; Committee Member: Realff, Matthew. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Style APA, Harvard, Vancouver, ISO itp.

37

Junay, Alexandra. "Étude des propriétés électroniques et de transport multi-échelle de jonctions tunnel Au/Alcanethiols/n-GaAs(001)". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S024/document.

Pełny tekst źródła

Streszczenie:

Les hétérostructures hybrides organique-inorganique présentent des propriétés intéressantes, notamment pour des applications dans le domaine de l’électronique et de la spintronique. Notre intérêt s’est porté particulièrement sur la réalisation d’hétérostructures de type Métal/Monocouche organique/Semiconducteur, dont l’étape de reprise de top-contact métallique reste actuellement un verrou majeur à la réalisation de telles jonctions. L’expérience de l’équipe sur des hétérostructures de type MOS (Métal/Oxyde/Semiconducteur), ainsi que les différentes techniques de surface et de transport disponibles au laboratoire, sont appliquées ici à l’étude de ces hétérostructures hybrides. En particulier, la Microscopie à Emission d’Electrons Balistiques (BEEM) permet d’étudier localement les propriétés électroniques des hétérostructures, avec une résolution spatiale nanométrique. A partir du système Au/GaAs(001) bien connu au laboratoire, nous avons intercalé une monocouche d’alcanethiols à l’interface, pour former des hétérostructures de type Au/Alcanethiols/GaAs(001), entièrement préparées sous ultra-vide. Lors du dépôt d’or à température ambiante, les images BEEM ont révélé des interfaces hétérogènes, avec des zones où le peigne moléculaire est court-circuité ou non par le métal. Une analyse quantitative en spectroscopie BEEM des zones non court-circuitées a mis en évidence des signatures particulières, avec une première contribution associée au passage tunnel des électrons à travers le peigne moléculaire, et une seconde contribution, à plus haute énergie, révélant l’existence de nouveaux canaux de conduction associés à l’existence d’états inoccupés dans la monocouche organique. Les effets de l’épaisseur du métal déposé, de la longueur de chaîne des molécules organiques, ainsi que du groupe terminal de la chaîne organique, ont été discutés. Afin d’améliorer le dépôt du contact métallique, un dispositif expérimental original a permis de déposer l’or sur le substrat refroidi, sur lequel une couche tampon de Xénon est condensée (méthode BLAG : Buffer Layer Assisted Growth). L’analyse BEEM de ces hétérostructures a révélé ici des interfaces homogènes, sans pénétration du métal. Des signatures spectroscopiques similaires aux zones non court-circuitées précédentes ont été mises en évidence. Une étude complète de ces hétérostructures préparées par la méthode BLAG a été réalisée via des mesures de transport à l’échelle macroscopique (J(V) et C(V)), ainsi que des mesures de photoémission par rayonnement synchrotron. Ces mesures ont confirmé le caractère reproductible des jonctions formées, avec des hauteurs de barrière en accord avec celles déterminées par BEEM
In molecular electronics and spintronics, top-contact metal electrode deposition on organic molecular monolayer (OML)/semiconductor hybrid heterostructures is still a critical issue, leading to metal penetration through the molecules and monolayer’s damage. The experimental set-ups available in the lab and the team’s experience in inorganic-inorganic heterostructures are here applied to hybrid organic-inorganic heterostructures. In particular, the Ballistic Electron Emission Microscopy (BEEM), a technique derived from Scanning Tunneling Microscopy (STM), allows to study electronic properties of such heterostructures, at a nanometer scale. Starting from the well-known Au/GaAs(001) Schottky contact, we here intercalate an alkanethiols monolayer, in order to obtain Au/Alkanethiols/GaAs(001) heterostructures, fully grown in ultra-high vacuum environment. In the case of room-temperature metal deposition, BEEM imaging reveals domains which are short-circuited or not by the metal. A quantitative analysis of non-short-circuited interfaces is realized by BEEM in spectroscopy mode. Particular fingerprints are obtained, with a first component related to electron tunnel transport through the monolayer, and a second component, at higher energy, related to first unoccupied states of the molecular layer reachable for electrons. The effects of metal thickness, molecular chain length and terminal group are discussed. In order to minimize the degree of gold penetration, an alternative top-contact deposition method is used, based on buffer-layer assisted growth (BLAG). BEEM studies on these heterostructures reveal homogeneous interfaces without metal penetration, and similar spectroscopic fingerprints. Complementary studies at macroscopic scale (J(V) and C(V) transport measurements and photoemission by synchrotron radiation) confirm the reproducible character of the junctions with barrier height values similar to the ones obtained by BEEM

Style APA, Harvard, Vancouver, ISO itp.

38

Gingerich, Mark Bryant. "Joining Carbon Fiber and Aluminum with Ultrasonic Additive Manufacturing". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461161262.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

39

Li, Shanghua. "Engineering nanomaterials with enhanced functionality". Licentiate thesis, KTH, Materials Science and Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3906.

Pełny tekst źródła

Streszczenie:

This thesis deals with the engineering of novel nanomaterials, particularly nanocomposites and nanostructured surfaces with enhanced functionalities. The study includes two parts; in the first part, an in situ sol-gel polymerization approach is used for the synthesis of polymer-inorganic hybrid material and its exceptional transparent UV-shielding effect has been investigated. In the second part, electrodeposition process has been adapted to engineer surfaces and the boiling performance of the fabricated nanostructured surfaces is evaluated.

In the first part of the work, polymer-inorganic hybrid materials composed of poly(methylmethacrylate) (PMMA) and zinc compounds were prepared by in situ sol-gel transition polymerization of zinc complex in PMMA matrix. The immiscibility of heterophase of solid organic and inorganic constituents was significantly resolved by an in situ sol-gel transition polymerization of ZnO nanofillers within PMMA in the presence of dual functional agent, monoethanolamine, which provided strong secondary interfacial interactions for both complexing and crosslinking of constituents.

In the second part of the work, nanoengineering on the surface of copper plates has been performed in order to enhance the boiling heat transfer coefficient. Micro-porous surfaces with dendritic network of copper nanoparticles have been obtained by electrodeposition with dynamic templates. To further alter the grain size of the dendritic branches, the nanostructured surfaces underwent a high temperature annealing treatment.

Comprehensive characterization methods of the polymer-inorganic hybrid materials and nanoengineered surfaces have been undertaken. XRD, 1H NMR, FT-IR, TGA, DSC, UV-Vis, ED, SEM, TEM and HRTEM have been used for basic physical properties. Pool boiling tests were performed to evaluate the boiling performance of the electrodeposited nanostructured micro-porous structures.

The homogeneous PZHM exhibited enhanced UV-shielding effects in the entire UV range even at very low ZnO content of 0.02 wt%. Moreover, the relationship between band gap and particle size of incorporated ZnO by sol-gel process was in good agreement with the results calculated from the effective mass model between bandgap and particle size. The fabricated enhanced surface has shown an excellent performance in nucleate boiling. At heat flux of 1 W/cm2, the heat transfer coefficient is enhanced over 15 times compared to a plain reference surface. A model has been presented to explain the enhancement based on the structure characteristics.

Style APA, Harvard, Vancouver, ISO itp.

40

Haaken, Daniela. "Innovative Desinfektionsverfahren zur Brauchwassergewinnung in der dezentralen Abwasserbehandlung - Elektrolyse und UV/Elektrolyse-Hybridtechnik". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-166834.

Pełny tekst źródła

Streszczenie:

According to estimates of the United Nations Environment Programme (UNEP), more than 1.8 billion people will be living in countries or regions with absolute water scarcity by 2025. The pressure on water resources is increased not only in arid and semiarid regions, but also in fast growing megacities around the world as a result of, amongst other factors, the changing nutritional and consumer behavior (rising living standards). Over 90 % of the annual water consumption of the newly industrializing and developing countries in the arid and semiarid climate zone is used for agricultural irrigation to ensure the nutrition of the population. Thus, since the beginning of the 20th century, the planned/controlled reuse of wastewater has developed into a central task of the sustainable water resources management. Wastewater represents a valuable resource in view of its composition (e. g. nutrients P, N for soil fertilizing) and its reliable, weather-independent availability in every household. The establishment of a closed-loop water management can enhance the efficiency of water usage. Therefore, activities in research and development are currently focused on decentralized and semi-centralized concepts, since their structures offer better conditions for the establishment of closed-loop systems and innovations in wastewater technology can be implemented more easily. In general, the hygienic quality requirements for wastewater reuse are predominantly oriented towards the planned usage. These are, in turn, regulated by thresholds and guidance values, e. g. for faecal indicator bacteria (e. g. faecal coliforms: E. coli), in widely differing norms and legal provisions specific to the respective countries. In Germany since 2005, small wastewater treatment plants can obtain the discharge class +H by the German Institute for Civil Engineering (DIBt: Deutsches Institut für Bautechnik) if secondary effluents contain less than 100 faecal coliforms (E. coli) per 100 mL. This ensures a safe effluent seepage in karst and water protection areas. Due to the infectious risk caused by a multitude of pathogens (bacteria, viruses, worm eggs, protozoa) which are still contained in wastewater after mechanical-biological treatment, specific disinfection methods are indispensable for their satisfactory reduction. Demands on disinfection methods for wastewater reclamation are quite complex. They should be characterized by a high and constant disinfection efficiency at low or moderate formation of disinfection by-products. The reclaimed wastewater should be able to be stored safely. Moreover, the disinfection method should be technically simple, scaleable, space-saving, subjected to low maintenance and realized at moderate investment and operating costs without applying external toxic chemicals. Established methods in decentralized wastewater disinfection are mainly based on membrane and UV technologies. However, these methods are currently working under high operating costs (high maintenance and cleaning efforts). Furthermore, the high investment costs of the membrane filtration are disadvantageous. In addition, both methods do not provide a disinfection residual. Thus, further research is required for the development and testing of alternative disinfection technologies. Against this background, the applicability of the electrolysis and UV/electrolysis hybrid technology for the decentralized wastewater reclamation was investigated and assessed in this dissertation. Results have shown that the electrochemical disinfection of biologically treated wastewater represents an efficient method at temperatures of > 6 °C, pH values of < 8.5 and DOC con-centrations of < 22 mg L-1. Under these conditions, an E. coli reduction of four log levels was achieved at a concentration of free chlorine ranging from 0.4 mg L-1 to 0.6 mg L-1 and at an after-reaction time of 15...20 min. However, it becomes simultaneously apparent that low temperatures, high pH values and high DOC concentrations are limiting parameters for this disinfection method to reclaim biologically treated wastewater. A high energy consumption of the electrolysis cell equipped with boron-doped diamond (BDD) electrodes (2...2.6 kWh m-3) represents a further unfavourable effect. Moreover, the undesired formation of chlorate (c = 1.3 mg L-1) and perchlorate (c = 18 mg L-1) at BDD electrodes can be considered as critical, since these disinfection by-products are, amongst others, human-toxicologically relevant. The concentration of adsorbable organically bound halogens (AOX) and trihalomethanes (THMs) proved to be marginal to moderate. Due to the synergistic effect of the combined application of UV irradiation (primary disinfection method) and electrolysis, the disadvantages of the single methods can be compensated. Decisive drawbacks of UV irradiation are photo and dark repair mechanisms of reversibly damaged bacteria. It was observed that the reactivation of reversibly UV-damaged E. coli even occurs at low temperatures (T = 10 °C) and strongly differing pH values (pH = 5.7...8.1) as well as at low light intensities and in darkness to an extent excluding a safe usage and storage of the reclaimed wastewater. The reactivation processes might be lowered by increased UV fluences. However, this is limited by high concentrations of total suspended solids (TSS). In spite of high UV fluences of > 400 J m-1, no complete removal of E. coli bacteria can be achieved at TSS concentrations of > 17 mg L-1. Therefore, it is indispensable to prevent bacterial reactivation caused by photo and dark repair processes. This topic was studied in the current work by electrochemically produced oxidants using an electrolysis cell positioned downstream of the UV unit. Results have shown that photo and dark reactivation were completely prevented by oxidants in a total concentration of 0.5...0.6 mg L-1 at a TSS concentration of 8...11 mg L-1, at pH values ranging from 5.7 to 8.1 and at temperatures ranging from 10 °C to 30 °C (t = 24....72 h). Even at a high TSS concentration of 75 mg L-1, the reactivation of E. coli (ctotal oxidants = 1.8 mg L-1) and, up to a TSS concentration of 32 mg L-1, the reactivation of total coliforms (except E. coli, ctotal oxidants = 1.0 mg L-1) can be prevented at a high initial germ concentration of 2…3 105 per 100 mL. The lowest energy consumption could be observed when mixed oxide electrodes (MOX electrodes) were applied. This result and the fact that no chlorate and perchlorate were observed at MOX electrodes argue for the application of these electrodes in practice. All in all, the UV/electrolysis hybrid technology represents an energy-efficient method for reclamation of biologically treated wastewater with TSS concentrations ranging from < 11 to 32 mg L-1 (E = 0.17…0.24 kWh m-3, MOX electrodes). Thereby, the reclaimed wastewater meet the hygienic quality requirements for a multitude of reuse categories starting from agricultural irrigation to urban and recreational reuse. Moreover, the requirements of the discharge class +H (100 faecal coliforms (E. coli) per 100 mL) are complied with reliably. The operational stability of the UV/electrolysis hybrid technology should also be ensured within the required maintenance intervals (t > 6 months). The undesired formation of coverings caused by biofouling processes on quartz glass surfaces could be prevented by electrochemically produced oxidants in a total concentration of 1 mg L-1 within an experimental duration of 5.5 months. However, the application of the UV/electrolysis hybrid technology is limited by increased particle concentrations and faecal loadings (initial E. coli concentration). The resulting enhanced demand of electrochemically produced oxidants for the prevention of bacterial reactivation results in a considerable increase of the electric charge input and energy consumption.

Style APA, Harvard, Vancouver, ISO itp.

41

Jenkins, Toni E. "Introgression of genes from rape to wild turnip". Lincoln University, 2005. http://hdl.handle.net/10182/1844.

Pełny tekst źródła

Streszczenie:

Introgression of genes from crops into ruderal populations is a multi-step process requiring sympatry, synchronous flowering, chromosomal compatibility, successful pollination and development of the zygote, germination, establishment and reproduction of hybrid progeny. The goal of this thesis was to generate data on as many steps in this process as possible and integrate them into a predictive statistical model to estimate the likelihood of successful introgression under a range of scenarios. Rape (Brassica napus) and wild turnip (B. rapa var. oleifera) were used as a model system. A homozygous dominant mutation in the rape genome conferring herbicide resistance provided a convenient marker for the study of introgression. Potential differences between wild turnip populations from a wide range of geographic locations in New Zealand were examined. Hand pollination established the genetic compatibility of rape and wild turnip and a high potential for gene introgression from rape to wild turnip. Interspecific hybrids were easily generated using wild turnip as the maternal plant, with some minor differences between wild turnip populations. The frequency of successful hybridisation between the two species was higher on the lower raceme. However, the upper raceme produced more dormant interspecific hybrid seed. Field trials, designed to imitate rare rape crop escapes into the ruderal environment, examined the ability of rare rape plants to pollinate wild turnip plants over four summers. At a ratio of 1 rape plant for every 400 wild turnip plants, the incidence of interspecific hybridisation was consistently low (<0.1 to 2.1 % of total seed on wild turnip plants). There was a significant year effect with the first season producing significantly more seed and a greater frequency of interspecific hybrid progeny than the other years. The frequency of interspecific hybrid progeny increases when the ratio of rape: wild turnip plant numbers increases. The relative importance of anemophily and entomophily in the production of interspecific hybrids was examined. Wild turnip plants produced twice as many seeds with bee pollination relative to wind pollination. However, the frequency of interspecific hybrids under wind pollination was nearly twice that for bee pollination. Light reflectance patterns under UV light revealed a marked difference between wild turnip and rape flowers compared to near identical appearance under visible light. The data indicates that bees are able to distinguish between rape and wild turnip flowers and exhibit floral constancy when foraging among populations with these two species. Hybrid survival in the seed bank, germination and seedling establishment in the field are important components of fitness. Seed banks established in the soil after the field trials described above germinated in subsequent spring seasons. The predominantly brassica weed populations were screened for herbicide resistance and the numbers of interspecific hybrids germinating compared to the original frequency in the field trial results. Frequency of interspecific hybrids was reduced in the populations compared to the original seed deposit. Seed with a known frequency of interspecific hybrid seed was sown in a separate trial, and the frequency of interspecific hybrids compared at 0, 4, 6, and 8 weeks after sowing. Poor germination resulted limited competition between seedlings, however the frequency of interspecific hybrids declined over time indicating low plant fitness. There were no significant population effects on any parameters tested. Interspecific hybrids grown in a glasshouse were backcrossed to the parental species and selfed within the plant and within populations. Pollen from the interspecific hybrids was found to have markedly reduced fertility. Interspecific hybrid plants had low female fertility, with the majority (88%) of the pollinated flowers aborting the siliques. Of the remaining siliques, most (98%) had only one to three seeds per silique. Inheritance of the herbicide resistance gene was regular in backcrosses but highly skewed following self pollination with an excess of herbicide-sensitive progeny. Production of a stochastic predictive model integrated the information acquired over the practical work phase of this thesis and utilised the capabilities of @risk, a new application of a risk analysis tool. The three outputs examined were the number of flowering plants resulting from backcrosses to rape and wild turnip and self pollination of the interspecific hybrid progeny. Five scenarios were modelled and all demonstrated the high likelihood of introgression failure in this system. In all scenarios, >75% of simulations resulted in no interspecific hybrid progeny surviving to flowering in the third generation. In all scenarios, and for all three outputs, the seed set on the interspecific hybrids of the second generation was the major factor that limited the number interspecific hybrid progeny surviving to flowering in the third generation.

Style APA, Harvard, Vancouver, ISO itp.

42

Liang, Chin-Chuan, i 梁錦釧. "The Study on the Key Success Factors for UAV Industry - An Empirical Study of Hybrid-VTOL UAV". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/cdzfxm.

Pełny tekst źródła

Streszczenie:

碩士
國立臺北商業大學
企業管理系研究所
107
UAV (unmanned aerial vehicle，UAV) industry is an innovation-driven technology sector. Other than convenience and versatility, the "unmanned" characteristics of UAV provides a low-cost alternative to save invaluable human lives and thus became a brand-new blooming industry. This research adopt the FAHP (fuzzy multi-criteria decision-making method) method to study the newly emerging Hybrid-Wing VTOL (Vertical Take Off and Landing) UAV industry with four major aspects—technology, organization, environment, and cost. Seventeen facets, under the four major aspects, are identified as key success factors in the following, namely the flight control, payload weight, endurance time, vehicle structure, propulsion technology, operational capabilities, financial resources, human resources, customization capabilities, regulatory integrity, economic size, supply chain integrity, market demand, R&D costs, manufacturing costs, commercial promotion and operating expenses. A questionnaire was carefully designed for FAHP study to include the above mentioned four major aspects and seventeen facets of key success factors and important conclusions from the statistical analysis of the surveys and opinions of professionals from related fields were then reviewed. We hope, the results of this study may offer companies, currently in or intending to get into this industry, with recommendations on future strategy and operation suggestion. Furthermore, the report should also provide technology industry suggestion to improve the success rate of product development.

Style APA, Harvard, Vancouver, ISO itp.

43

Yu-MingSyu i 許育銘. "Hybrid Solution for UAV Multiple Target Path planning using Genetic Algorithm with Dynamic Programming". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/76642335772446190569.

Pełny tekst źródła

Streszczenie:

碩士
國立成功大學
航空太空工程學系
103
The major objective of this thesis is to present a hybrid method by integrating, Genetic Algorithm with Dynamic Programming, for solving multiple target path planning in implementation into UAV system. In order to guarantee the safety requirement and feasibility for path planning, the flight path planning system (FPPS) necessarily consider the path security, UAV’s capability and so on. The Virtual Flight Map is built at first and the path planning would program in the map by algorithms. Between two target locations, Genetic Algorithm finds the optimal path with suitable fitness function. Then, with the distances matrix between every pair of multiple targets, Dynamic Programming (DP) expands the two targets path planning to multiple targets. The DP decide what is the visiting sequence of multiple targets which visits all targets just once and returns to the starting location. It must be the shortest distance of tour sequence. Finally, UAV system is sat up and performs flight path tracking to verify the flight path planning system.

Style APA, Harvard, Vancouver, ISO itp.

44

Matlock, Jay Michael Todd. "Evaluation of hybrid-electric propulsion systems for unmanned aerial vehicles". Thesis, 2019. http://hdl.handle.net/1828/11484.

Pełny tekst źródła

Streszczenie:

The future of aviation technology is transitioning to cleaner, more efficient and higher endurance aircraft solutions. As fully electric propulsion systems still fall short of the operational requirements of modern day aircraft, there is increasing pressure and demand for the aviation industry to explore alternatives to fossil fuel driven propulsion systems. The primary focus of this research is to experimentally evaluate hybrid electric propulsion systems (HEPS) for Unmanned Aerial Vehicles (UAV) which combine multiple power sources to improve performance. HEPS offer several potential benefits over more conventional propulsion systems such as a smaller environmental impact, lower fuel consumption, higher endurance and novel configurations through distributed propulsion. Advanced operating modes are also possible with HEPS, increasing the vehicle’s versatility and redundancy in case of power source failure. The primary objective of the research is to combine all of the components of a small-scale HEPS together in a modular test bench for evaluation. The test bench uses components sized for a small-scale UAV including a 2.34kW two-stroke 35cc engine and a 1.65kW brushless DC motor together with an ESC capable of regenerative braking. Individual components were first tested to characterize performance, and then all components were assembled together in a parallel configuration to observe system-level performance. The parallel HEPS is capable of functioning in the four required operating modes: EM Only, ICE Only, Dash Mode (combined EM and ICE power) as well as Regenerative Mode where the onboard batteries get recharged. Further, the test bench was implemented with a supervisory controller to optimize system performance and run each component in the most efficient region to achieve torque requirements programmed into mission profiles. The logic based controller operates with the ideal operating line (IOL) concept and is implemented with a custom LabView GUI. The system is able to run on electric power or ICE power interchangeably without making any modifications to the transmission as the one-way bearing assembly engages for whichever power source is rotating at the highest speed. The most impressive of these sets of tests is the Dash mode testing where the output torque of the propeller is supplied from both the EM and ICE. Working in tandem, it was proved that the EM was drawing 19.9A of current which corresponds to an estimated 0.57Nm additional torque to the propeller for a degree of hybridization of 49.91%. Finally, the regenerative braking mode was proven to be operational, capable of recharging the battery systems at 13A. All of these operating modes attest to the flexibility and convenience of having a hybrid-electric propulsion system. The results collected from the test bench were validated against the models created in the aircraft simulation framework. This framework was created in MATLAB to simulate the performance of a small UAV and compare the performance by swapping in various propulsion systems. The purpose of the framework is to make direct comparisons of HEPS performance for parallel and series architectures against conventional electric and gasoline configuration UAVs, and explore the trade-offs. Each aircraft variable in the framework was modelled parametrically so that parameter sweeps could be run to observe the impact on the aircraft’s performance. Finally, rather than comparing propulsion systems in steady-state, complex mission profiles were created that simulate real life applications for UAVs. With these experiments, it was possible to observe which propulsion configurations were best suited for each mission type, and provide engineers with information about the trade-offs or advantages of integrating hybrid-electric propulsion into UAV design. In the Pipeline Inspection mission, the exact payload capacities of each aircraft configuration could be observed in the fuel burn versus CL,cruise parameter sweep exercise. It was observed that the parallel HEPS configuration has an average of 3.52kg lower payload capacity for the 35kg aircraft (17.6%), but has a fuel consumption reduction of up to 26.1% compared to the gasoline aircraft configuration. In the LIDAR Data collection mission, the electric configuration could be suitable for collection ranges below 100km but suffers low LIDAR collection times. However, at 100km LIDAR collection range, the series HEPS has an endurance of 16hr and the parallel configuration has an endurance of 19hr. In the Interceptor mission, at 32kg TOW, the parallel HEPS configuration has an endurance/TOW of 1.3[hr/kg] compared to 1.15[hr/kg] for the gasoline aircraft. This result yields a 13% increase in endurance from 36.8hr for gasoline to 41.6hr for the parallel HEPS. Finally, in the Communications Relay mission, the gasoline configuration is recommended for all TOW above 28kg as it has the highest loiter endurance.
Graduate

Style APA, Harvard, Vancouver, ISO itp.

45

"Power Management for Fuel Cell and Battery Hybrid Unmanned Aerial Vehicle Applications". Master's thesis, 2016. http://hdl.handle.net/2286/R.I.40735.

Pełny tekst źródła

Streszczenie:

abstract: As electric powered unmanned aerial vehicles enter a new age of commercial viability, market opportunities in the small UAV sector are expanding. Extending UAV flight time through a combination of fuel cell and battery technologies enhance the scope of potential applications. A brief survey of UAV history provides context and examples of modern day UAVs powered by fuel cells are given. Conventional hybrid power system management employs DC-to-DC converters to control the power split between battery and fuel cell. In this study, a transistor replaces the DC-to-DC converter which lowers weight and cost. Simulation models of a lithium ion battery and a proton exchange membrane fuel cell are developed and integrated into a UAV power system model. Flight simulations demonstrate the operation of the transistor-based power management scheme and quantify the amount of hydrogen consumed by a 5.5 kg fixed wing UAV during a six hour flight. Battery power assists the fuel cell during high throttle periods but may also augment fuel cell power during cruise flight. Simulations demonstrate a 60 liter reduction in hydrogen consumption when battery power assists the fuel cell during cruise flight. Over the full duration of the flight, averaged efficiency of the power system exceeds 98%. For scenarios where inflight battery recharge is desirable, a constant current battery charger is integrated into the UAV power system. Simulation of inflight battery recharge is performed. Design of UAV hybrid power systems must consider power system weight against potential flight time. Data from the flight simulations are used to identify a simple formula that predicts flight time as a function of energy stored onboard the modeled UAV. A small selection of commercially available batteries, fuel cells, and compressed air storage tanks are listed to characterize the weight of possible systems. The formula is then used in conjunction with the weight data to generate a graph of power system weight versus potential flight times. Combinations of the listed batteries, fuel cells, and storage tanks are plotted on the graph to evaluate various hybrid power system configurations.
Dissertation/Thesis
Masters Thesis Engineering 2016

Style APA, Harvard, Vancouver, ISO itp.

46

Yong-HuiHuang i 黃詠暉. "Design and Implement of OPC UA Aggregating Server Based on Hybrid Architecture of Node Updating". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/d56ht7.

Pełny tekst źródła

Streszczenie:

碩士
國立成功大學
工程科學系
107
In view of the messy in the communication protocols in the industry, many companies such as Microsoft have proposed the OPC UA protocol to try to standardize the entire industry to effectively integrate various vendors. Due to the excessive sources of data and the lack of collation and integration, the academic community and the industry have the prototype of aggregating servers. To solve the problem of excessive network load caused by traditional passive updating node, the method is proposed to combine passive updating and OPC UA Pub/Sub which is the newest standard proposed by OPC foundation for actively updating the node. With the help of network bandwidth monitoring which is part of signaling server, this method can not only solve the problem of excessive repetition or excessive traffic caused by the user accessing the aggregation server too frequently but avoid network congestion caused by too frequent source OPC UA server node updates when use Pub/Sub to update node.

Style APA, Harvard, Vancouver, ISO itp.

47

Boruah, Buddha Deka. "Coupled Optical and Electrochemical Properties of ZnCo2O4 for Radiation Sensitive Supercapacitor : An Approach Towards Self-powered Photosensitive Energy Storage". Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4242.

Pełny tekst źródła

Streszczenie:

Recently, the fields of energy conversion and storage have drawn great interests in the research community due to the wide range of practical applications in the society. Among them, photodetector (PD) and supercapacitor (SC) have attracted potential imprints for energy conversion and storage applications. This thesis is thus focused on the fabrication of efficient self-powered ultraviolet (UV) PD and SC based on optically and electrochemically active heterostructure materials. Firstly, self-powered UV PD is explored based on one dimensional zinc oxide (ZnO) nanorods (NRs). The charge carrier density of ZnO NRs was modified by doping of halogen elements to enhance the self-powered photo response. Interestingly, 5.5 times enhancement in the photo response of halogen doped ZnO NRs was noticed as compared to pristine ZnO NRs. Further charge carrier modification of ZnO NRs was performed via hydrogenation process of ZnO NRs. Efficient increase in the carrier density of hydrogenated ZnO (H: ZnO) NRs allows enhancing the photo response to nearly 900% and 82% as compared to pristine ZnO NRs and halogen doped ZnO NRs, respectively. The optically as well as electrochemically active heterostructure was then introduced by integrating zinc cobalt oxide (ZnCo2O4) with H: ZnO NRs to form ZnCo2O4/H: ZnO NRs for the applications of UV PD and SC. Further enhancement of 75% in the photo response of ZnCo2O4/H: ZnO NRs was obtained as compared to H: ZnO NRs in self-powered configuration. The photo response behaviour of the ZnCo2O4/H: ZnO NRs PD was investigated under different UV illumination intensities in absence of external bias voltage. A power law dependence of the response of the PD on UV illumination intensity was displayed. Moreover, faster photon detection speed in the order of few milliseconds was also achieved for the self-powered PD. Furthermore, efficient UV detection efficiency for the PD was obtained. The electrochemical performance of the ZnCo2O4/H: ZnO NRs was then investigated in detail. Efficient energy storage performance of ZnCo2O4/H: ZnO NRs was obtained where 63% enhancement in energy storage performance of ZnCo2O4/H: ZnO NRs electrode was observed as compared to ZnCo2O4 alone. For the investigation of energy storage performance of ZnCo2O4/H: ZnO NRs in presence of UV illumination, a solid-state symmetric SC (SSC) was fabricated composed of ZnCo2O4/H: ZnO NRs electrodes. The energy storage performance of the SSC was analysed both in the absence and the presence of UV illumination. An appreciable, 2.7 times enhancement in specific capacitance of the SSC was noticed under UV illumination as compared to the absence of UV. It was found that with the increase in UV illumination intensity, the electrochemical performance of the SSC increases linearly. The capacitance stability of the SSC was further studied for 4000 cycles both in the presence and the absence of UV. Notably, only 2% degradation of the capacitive response of the SSC was noticed under UV illumination as compared to absence of UV. Moreover, 175% enhancement in energy density of the SSC was obtained in presence of UV. To expand the working voltage of the SSC, an asymmetric solid-state SC (ASC) was fabricated composed of ZnCo2O4/H: ZnO NRs as positive electrode and activated carbon (AC) as negative electrode. The working voltage of the ASC is increased from 0.6 to 1.5 V, thus providing an increase in overall energy storage performance of the ASC as compared to SSC. The charge storage mechanism of the ASC was discussed in detail. For the direct practical implementation of the ASC, a PD was fabricated based on ZnCo2O4/H: ZnO NRs as photosensitive material and connected in series configuration with the ASC. As-fabricated ASC can easily offer desired power to the ZnCo2O4/H: ZnO NRs PD during the conversion of optical to electrical signal. Increase in the photo response of the PD was observed in presence of UV illumination. For further expansion of the working voltage of ASC, three ASCs were connected internally in series to form solid-state asymmetric tandem SC (ATSC). The electrochemical response of the ATSC electrodes composed of hybrid reduced graphene oxide (rGO)-carbon nanotubes (CNTs)-ZnCo2O4 (rGO-CNTs-ZnCo2O4) as positive and rGO-CNTs-iron (III) oxide (rGO-CNTs- Fe2O3) negative electrodes were performed systematically. The efficient energy storage performance of the ATSC is due to the synergistic contribution of each of individual nanomaterials in the hybrid electrodes. The working voltage of the ATSC was measured to be 4.5 V which is three times larger than ASC. As a result, a significant increase in energy density (61%) and power density (33%) was noticed as compared to ASC. Moreover, the electrochemical measurement of the ATSC was also studied at different mechanical bending deformation angles ranging from 0 to 60o at a working voltage of 4.5 V. Interestingly, no significant deviation in electrochemical response was observed under the mechanical deformations of the ATSC. In addition, the energy storage performance of the ATSC was measured at different working voltage ranging from 1.5 to 4.5 V. With increase in the working voltage, the energy storage performances (energy density and power density) of the ATSC increase following a linear function. In addition, for the direct practical application, ZnCo2O4/H: ZnO NRs PD was driven by the ATSC used as a power source for the detection of UV light.

Style APA, Harvard, Vancouver, ISO itp.

48

Banerjee, Sreetama. "HED-TIE: A wafer-scale approach for fabricating hybrid electronic devices with trench isolated electrodes and its application in sensing devices". 2017. https://monarch.qucosa.de/id/qucosa%3A34062.

Pełny tekst źródła

Streszczenie:

Die organisch-anorganische Hybridelektronik bietet verschiedene Möglichkeiten zur Entwicklung neuartiger Bauelemente, welche die Vorteile von organischen und anorganischen Halbleitern vereinen. Planare Bauelemente werden typischerweise mittels Schattenmasken-basierter Strukturierung hergestellt. Ein Grund hierfür ist die Empfindlichkeit organischer Halbleiter gegenüber Ultraviolettem Licht und Lösungsmitteln, welche in den Standard-Photolithographieprozessen eingesetzt werden. Die Schattenmasken-Strukturierung führt allerdings zu Bauelementen mit kleinsten Abmessungen im Mikrometerbereich. Für die Reduzierung der Kanalabmessungen von planaren organisch-anorganischen Hybridbauelementen unterhalb eines Mikrometers ist die Elektronenstrahllithographie die am häufigsten verwendete Technik. Aufgrund des hohen Kosten- und Zeitaufwandes ist es nicht möglich, diese Technik für Wafermaßstab-Herstellung in der industriellen Anwendung einzusetzen. In dieser Arbeit wird eine alternative Technologie zur Herstellung von planaren Bauelementen mit isolierten Grabenelektroden und Kanalabmessungen von wenigen Hundert Nanometer bis unter 100 nm vorgestellt. Gräben kleiner als ein Mirkometer werden zunächst auf Silizium-Substraten strukturiert und anschließend mit einer isolierenden SiO2 Schicht aufgefüllt. Diese hilft dabei die gewünschten Elektrodenabstände, also die gewünschte Kanallänge, zu erreichen. Die Flexibilität des neuen Herstellungsverfahrens ermöglicht es nicht nur verschiedenen Kanallängen und Bauelement-Geometrie, sondern auch die Verwendung verschiedener Materialien für Elektroden und organischen Kanäle. Dies wiederum ermöglicht eine Vielfalt von potentiellen Anwendungen der hybriden Bauelemente. In dieser Arbeit wurde 6,13-bis (triisopropylsilylethinyl)-Pentacen (TIPS-Pentacen) Lösung und metallfreie Phthalocyanin als organisches Material verwendet und als Elektrodenmaterial diente Gold. Die entstandenen auf TIPS-Pentacen-Lösung basierenden planaren hybriden Bauelemente wurden für potentielle Anwendungen als optische sowie magnetoresistive Sensoren getestet.:Table of Contents Bibliografische Beschreibung 1 Chapter 1. Introduction 3 1.1 Organic-inorganic hybrid electronics 4 1.2 Inorganic semiconductors versus organic semiconductors 5 1.3 Electronic properties of a molecular layer 5 1.4 Vertical HEDs and planar HEDs 6 Chapter 2. Wafer-scale fabrication approach for planar HED-TIEs 8 2.1 Overview of nano-patterning techniques 8 (a) Electron beam lithography (EBL) 8 (b) Nanostencil lithography (NSL) 8 (c) Nanoimprint lithography (NIL) 9 2.2 Fabrication of planar organic-inorganic HED-TIEs 12 2.2.1 Trench refill approach for fabricating HED-TIEs 12 2.2.1.1 Deposition of the trench refill layer 15 2.2.1.2 Deposition of the organic channel material 16 (a) HED-TIE with thermally evaporated organic channel 16 (b) HED-TIE with solution processed organic channel 18 2.2.2 Spacer approach for fabricating HED-TIEs 21 2.2.2.1 Deposition of the isolation layer 23 2.3 Characterization techniques 26 (a) Electrical characterization 26 (b) Raman spectroscopy 26 (c) Photoluminescence spectroscopy 27 2.4 Summary and outlook 27 Chapter 3. Electrical characterization of HED-TIEs 29 3.1 Theoretical background 29 3.1.1 Space charge limited current (SCLC) conduction mechanism 29 3.2 Experimental details 32 3.3 Results and discussions 34 3.4 Summary and outlook 40 Chapter 4. Application of HED-TIEs as optical sensors 41 4.1 Photosensing properties of TIPS-pentacene based HED-TIEs 41 4.1.1 Theoretical background 41 4.1.2 Experimental details 43 4.1.3 Results and discussions 44 4.1.4 Summary and outlook 49 4.2 Photosensing properties of TIPS-pentacene based HED-TIEs with Au nanoparticles in the channel matrix 50 4.2.1 Theoretical background 50 4.2.2 Experimental details 51 4.2.3 Results and discussions 52 4.2.4 Summary and outlook 59 Chapter 5. Application of HED-TIE devices as magnetoresistive sensors 61 5.1 Theoretical background 61 5.1.1 Organic spintronics 61 5.1.2 Mechanisms of organic magnetoresistance (OMAR) 65 (a) Bipolaron model 68 (b) Electron-hole (e-h) pair model 69 (c) Exciton–charge interaction model 70 5.2. OMAR measurements on TIPS-pentacene OFETs and HED-TIEs 71 5.2.1 Experimental details 71 5.3 Results and discussions 73 5.4 Summary and outlook 79 Chapter 6. Summary and outlook 81 References 86 List of Figures 97 List of Tables 103 List of Abbreviations 104 Acknowledgements 106 List of Publications 108 List of Conference Presentations and Posters 109 Selbstständigkeitserklärung 111 Curriculum Vitae 112

Style APA, Harvard, Vancouver, ISO itp.

49

Haaken, Daniela. "Innovative Desinfektionsverfahren zur Brauchwassergewinnung in der dezentralen Abwasserbehandlung - Elektrolyse und UV/Elektrolyse-Hybridtechnik". Doctoral thesis, 2014. https://tud.qucosa.de/id/qucosa%3A28686.

Pełny tekst źródła

Streszczenie:

According to estimates of the United Nations Environment Programme (UNEP), more than 1.8 billion people will be living in countries or regions with absolute water scarcity by 2025. The pressure on water resources is increased not only in arid and semiarid regions, but also in fast growing megacities around the world as a result of, amongst other factors, the changing nutritional and consumer behavior (rising living standards). Over 90 % of the annual water consumption of the newly industrializing and developing countries in the arid and semiarid climate zone is used for agricultural irrigation to ensure the nutrition of the population. Thus, since the beginning of the 20th century, the planned/controlled reuse of wastewater has developed into a central task of the sustainable water resources management. Wastewater represents a valuable resource in view of its composition (e. g. nutrients P, N for soil fertilizing) and its reliable, weather-independent availability in every household. The establishment of a closed-loop water management can enhance the efficiency of water usage. Therefore, activities in research and development are currently focused on decentralized and semi-centralized concepts, since their structures offer better conditions for the establishment of closed-loop systems and innovations in wastewater technology can be implemented more easily. In general, the hygienic quality requirements for wastewater reuse are predominantly oriented towards the planned usage. These are, in turn, regulated by thresholds and guidance values, e. g. for faecal indicator bacteria (e. g. faecal coliforms: E. coli), in widely differing norms and legal provisions specific to the respective countries. In Germany since 2005, small wastewater treatment plants can obtain the discharge class +H by the German Institute for Civil Engineering (DIBt: Deutsches Institut für Bautechnik) if secondary effluents contain less than 100 faecal coliforms (E. coli) per 100 mL. This ensures a safe effluent seepage in karst and water protection areas. Due to the infectious risk caused by a multitude of pathogens (bacteria, viruses, worm eggs, protozoa) which are still contained in wastewater after mechanical-biological treatment, specific disinfection methods are indispensable for their satisfactory reduction. Demands on disinfection methods for wastewater reclamation are quite complex. They should be characterized by a high and constant disinfection efficiency at low or moderate formation of disinfection by-products. The reclaimed wastewater should be able to be stored safely. Moreover, the disinfection method should be technically simple, scaleable, space-saving, subjected to low maintenance and realized at moderate investment and operating costs without applying external toxic chemicals. Established methods in decentralized wastewater disinfection are mainly based on membrane and UV technologies. However, these methods are currently working under high operating costs (high maintenance and cleaning efforts). Furthermore, the high investment costs of the membrane filtration are disadvantageous. In addition, both methods do not provide a disinfection residual. Thus, further research is required for the development and testing of alternative disinfection technologies. Against this background, the applicability of the electrolysis and UV/electrolysis hybrid technology for the decentralized wastewater reclamation was investigated and assessed in this dissertation. Results have shown that the electrochemical disinfection of biologically treated wastewater represents an efficient method at temperatures of > 6 °C, pH values of < 8.5 and DOC con-centrations of < 22 mg L-1. Under these conditions, an E. coli reduction of four log levels was achieved at a concentration of free chlorine ranging from 0.4 mg L-1 to 0.6 mg L-1 and at an after-reaction time of 15...20 min. However, it becomes simultaneously apparent that low temperatures, high pH values and high DOC concentrations are limiting parameters for this disinfection method to reclaim biologically treated wastewater. A high energy consumption of the electrolysis cell equipped with boron-doped diamond (BDD) electrodes (2...2.6 kWh m-3) represents a further unfavourable effect. Moreover, the undesired formation of chlorate (c = 1.3 mg L-1) and perchlorate (c = 18 mg L-1) at BDD electrodes can be considered as critical, since these disinfection by-products are, amongst others, human-toxicologically relevant. The concentration of adsorbable organically bound halogens (AOX) and trihalomethanes (THMs) proved to be marginal to moderate. Due to the synergistic effect of the combined application of UV irradiation (primary disinfection method) and electrolysis, the disadvantages of the single methods can be compensated. Decisive drawbacks of UV irradiation are photo and dark repair mechanisms of reversibly damaged bacteria. It was observed that the reactivation of reversibly UV-damaged E. coli even occurs at low temperatures (T = 10 °C) and strongly differing pH values (pH = 5.7...8.1) as well as at low light intensities and in darkness to an extent excluding a safe usage and storage of the reclaimed wastewater. The reactivation processes might be lowered by increased UV fluences. However, this is limited by high concentrations of total suspended solids (TSS). In spite of high UV fluences of > 400 J m-1, no complete removal of E. coli bacteria can be achieved at TSS concentrations of > 17 mg L-1. Therefore, it is indispensable to prevent bacterial reactivation caused by photo and dark repair processes. This topic was studied in the current work by electrochemically produced oxidants using an electrolysis cell positioned downstream of the UV unit. Results have shown that photo and dark reactivation were completely prevented by oxidants in a total concentration of 0.5...0.6 mg L-1 at a TSS concentration of 8...11 mg L-1, at pH values ranging from 5.7 to 8.1 and at temperatures ranging from 10 °C to 30 °C (t = 24....72 h). Even at a high TSS concentration of 75 mg L-1, the reactivation of E. coli (ctotal oxidants = 1.8 mg L-1) and, up to a TSS concentration of 32 mg L-1, the reactivation of total coliforms (except E. coli, ctotal oxidants = 1.0 mg L-1) can be prevented at a high initial germ concentration of 2…3 105 per 100 mL. The lowest energy consumption could be observed when mixed oxide electrodes (MOX electrodes) were applied. This result and the fact that no chlorate and perchlorate were observed at MOX electrodes argue for the application of these electrodes in practice. All in all, the UV/electrolysis hybrid technology represents an energy-efficient method for reclamation of biologically treated wastewater with TSS concentrations ranging from < 11 to 32 mg L-1 (E = 0.17…0.24 kWh m-3, MOX electrodes). Thereby, the reclaimed wastewater meet the hygienic quality requirements for a multitude of reuse categories starting from agricultural irrigation to urban and recreational reuse. Moreover, the requirements of the discharge class +H (100 faecal coliforms (E. coli) per 100 mL) are complied with reliably. The operational stability of the UV/electrolysis hybrid technology should also be ensured within the required maintenance intervals (t > 6 months). The undesired formation of coverings caused by biofouling processes on quartz glass surfaces could be prevented by electrochemically produced oxidants in a total concentration of 1 mg L-1 within an experimental duration of 5.5 months. However, the application of the UV/electrolysis hybrid technology is limited by increased particle concentrations and faecal loadings (initial E. coli concentration). The resulting enhanced demand of electrochemically produced oxidants for the prevention of bacterial reactivation results in a considerable increase of the electric charge input and energy consumption.

Style APA, Harvard, Vancouver, ISO itp.

Rozprawy doktorskie na temat „Hybride uav”

Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych