Дисертації з теми "Diffusion en direct"
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1
Siotis, Georges. "Technological diffusion, foreign direct investment and convergence." Doctoral thesis, Universite Libre de Bruxelles, 1997. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212218.
2
Bliersbach, Andreas. "Hydrogen diffusion in nano-sized materials : investigated by direct imaging." Thesis, Uppsala universitet, Materialfysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-156033.
Анотація:
The kinetics of interstitial hydrogen are of great interest and importance for metal-hydride storage, purification, fusion and fission reactor technology, material failure processes, optical sensors for hydrogen gas and many other technologies. In particular nano-sized materials motivate fascinating applications and scientific questions. If hydrogen is absorbed in vanadium it alters the band structure around the Fermi energy. These modifications of the band structurelead to a change in the absorptance of vanadium which are in first order approximation proportional to the concentration. We present a methodto quantify chemical diffusion of hydrogen in nano-sized materials.The induced changes in the absorptance of vanadium hydride (VHx) thin-films are observed visually and in real-time as a function of position.Concentration profiles and their evolution in time, during chemicaldiffusion, were measured down to a hydrogen content corresponding tojust a few effective monolayers, randomly distributed within VHx. For concentrations reached via phase transitions distinct diffusional behavior was found, where a diffusion-front, a strong concentration gradient, migrates in the direction of the diffusive hydrogen flux. The results show that decreased size strongly influences the energy landscape and reveal different rate limiting steps for absorption and desorption.
3
Schnell, Sondre Kvalvåg, Thijs J. H. Vlugt, Jean-Marc Simon, Signe Kjelstrup, and Dick Bedeaux. "Direct calculation of the thermodynamic correction factor, gamma, from molecular dynamics simulations." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185607.
4
Valär, Adrian Luzi. "Direct numerical simulation of cellular structures in jet diffusion flames /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17678.
5
Pires, Karine. "Diffusion et transcodage à grande échelle de flux vidéo en direct." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066112/document.
Анотація:
Aujourd'hui, de nombreux appareils sont capables de capturer des vidéos en Full HD et d'utiliser une connexion réseau pour accéder à Internet. La popularisation des dispositifs et les efforts continus pour améliorer la qualité du réseau ont apporté un environnement propice à l'essor de la diffusion en direct. De par la grande quantité de contenu généré par les utilisateurs, la diffusion de flux en direct présente de nouveaux défis. Dans cette thèse, nous nous intéressons à la distribution et au transcodage des systèmes de diffusion en direct. Pour étudier les différent aspects des systèmes de diffusion en direct nous avons besoin de les caractériser et d'évaluer les solutions proposées avec des traces pertinentes. Par conséquent, notre première contribution est un ensemble de données et son analyse, contenant trois mois de traces de deux services de streaming en direct. Ensuite, nous avons exploré et développé des solutions pour la distribution du contenu produit par ces platesformes. L'un des défis est l'hétérogénéité de popularité des flux. Ceci implique généralement un surdimensionnement des services et par conséquent un gaspillage de ressources. Enfin, nous nous sommes focalisés sur les difficultés posées par le transcodage des flux en direct. Les opérations de transcodage sont coûteuses en ressources CPU et sont des étapes clés pour le Streaming à Débit Adaptatif (SDA). Nous montrons que le SDA est capable de réduire le coût en bande passante pour la distribution et d'augmenter la qualité d'expérience des téléspectateurs en échange d'un coût en ressources CPU. Pour comprendre le compromis entre les avantages et les coûts, nous formulons deux problèmes de gestionToday many devices are capable to capture full HD videos and to use its network connection to access Internet. The popularization of devices and continuous efforts to increase network quality has brought a proper environment for the rise of live streaming. Associated to the large scale of Users Generated Content (UGC), live streaming presents new challenges. In this thesis we target the delivery and transcoding of live streaming systems.First, to study the aspects we target of live streaming systems we need to characterize them and evaluate the proposed solutions with relevant traces. Therefore our first contribution is a data set, and its analysis, containing three months traces of two UGC live streaming services.Second, we explored and developed solutions for the delivery of the content produced by these platforms. One of the challenges is the heterogeneity among streams popularity, which generally implies over-provisioning and consequently resource waste. We show that there is a trade-off between the number of servers involved to broadcast the streams and the bandwidth usage among the servers. We also stress the importance to predict streams popularity in order to efficiently place them on the servers.Lastly, we target the difficulties concerning transcoding of live streams. The transcoding operations over streams are computing consuming and are key operations on adaptive bit rate streaming. We show that adaptive streaming is able to reduce the delivery bandwidth cost and to increase viewer quality of experience at the cost of computing resources. We formulate two management problems to address the trade-off between benefits and costs
6
Pires, Karine. "Diffusion et transcodage à grande échelle de flux vidéo en direct." Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066112.
Анотація:
Aujourd'hui, de nombreux appareils sont capables de capturer des vidéos en Full HD et d'utiliser une connexion réseau pour accéder à Internet. La popularisation des dispositifs et les efforts continus pour améliorer la qualité du réseau ont apporté un environnement propice à l'essor de la diffusion en direct. De par la grande quantité de contenu généré par les utilisateurs, la diffusion de flux en direct présente de nouveaux défis. Dans cette thèse, nous nous intéressons à la distribution et au transcodage des systèmes de diffusion en direct. Pour étudier les différent aspects des systèmes de diffusion en direct nous avons besoin de les caractériser et d'évaluer les solutions proposées avec des traces pertinentes. Par conséquent, notre première contribution est un ensemble de données et son analyse, contenant trois mois de traces de deux services de streaming en direct. Ensuite, nous avons exploré et développé des solutions pour la distribution du contenu produit par ces platesformes. L'un des défis est l'hétérogénéité de popularité des flux. Ceci implique généralement un surdimensionnement des services et par conséquent un gaspillage de ressources. Enfin, nous nous sommes focalisés sur les difficultés posées par le transcodage des flux en direct. Les opérations de transcodage sont coûteuses en ressources CPU et sont des étapes clés pour le Streaming à Débit Adaptatif (SDA). Nous montrons que le SDA est capable de réduire le coût en bande passante pour la distribution et d'augmenter la qualité d'expérience des téléspectateurs en échange d'un coût en ressources CPU. Pour comprendre le compromis entre les avantages et les coûts, nous formulons deux problèmes de gestionToday many devices are capable to capture full HD videos and to use its network connection to access Internet. The popularization of devices and continuous efforts to increase network quality has brought a proper environment for the rise of live streaming. Associated to the large scale of Users Generated Content (UGC), live streaming presents new challenges. In this thesis we target the delivery and transcoding of live streaming systems.First, to study the aspects we target of live streaming systems we need to characterize them and evaluate the proposed solutions with relevant traces. Therefore our first contribution is a data set, and its analysis, containing three months traces of two UGC live streaming services.Second, we explored and developed solutions for the delivery of the content produced by these platforms. One of the challenges is the heterogeneity among streams popularity, which generally implies over-provisioning and consequently resource waste. We show that there is a trade-off between the number of servers involved to broadcast the streams and the bandwidth usage among the servers. We also stress the importance to predict streams popularity in order to efficiently place them on the servers.Lastly, we target the difficulties concerning transcoding of live streams. The transcoding operations over streams are computing consuming and are key operations on adaptive bit rate streaming. We show that adaptive streaming is able to reduce the delivery bandwidth cost and to increase viewer quality of experience at the cost of computing resources. We formulate two management problems to address the trade-off between benefits and costs
7
Schnell, Sondre Kvalvåg, Thijs J. H. Vlugt, Jean-Marc Simon, Signe Kjelstrup, and Dick Bedeaux. "Direct calculation of the thermodynamic correction factor, gamma, from molecular dynamics simulations." Diffusion fundamentals 16 (2011) 72, S. 1-2, 2011. https://ul.qucosa.de/id/qucosa%3A13814.
8
Florin, Ernst-Ludwig, Tobias F. Bartsch, and Martin Kochanczyk. "Seeing is believing: direct visualization of fluctuations in biopolymer networks with 3D thermal noise imaging." Diffusion fundamentals 20 (2013) 10, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13531.
9
Driss, Slim. "Investissement direct étranger et diffusion technologique dans les pays en voie de développement." Toulouse 1, 1997. http://www.theses.fr/1997TOU10023.
Анотація:
L'objet de ce travail consiste à analyser le problème d'accès des pays en voie de développement (PVD) aux technologies nouvelles. L'investissement direct se présente comme le moyen le plus efficace de transfert technologique. Ce dernier doit naturellement s'accompagner d'une diffusion de bonne qualité dans le pays hôte : si cette dernière ne se produit pas les maigres flux à destination des PVD perdent une bonne part de leur intérêt. Autant la littérature a traité des incitations au transfert, autant elle a laissé de côté la problématique de la diffusion. La thèse vise à contribuer à combler cette lacune. Afin d'isoler le phénomène de diffusion, nous avons proposé un modèle d'investissement direct vertical, en supposant donc que le problème de la qualité de la technologie transférée est réglé. Le gouvernement du pays hôte intervient, dans un premier temps, en proposant une prime à l'investissement pour compenser l'insuffisance des avantages de localisation. Au regard du problème de diffusion au profit des firmes locales, une seconde intervention peut être requise lorsque le niveau endogène de diffusion technologique est trop faible. Le gouvernement fixe alors un niveau prédéterminé de qualité de la diffusion supérieur à celui qui serait choisi par la firme locale en l'absence d'intervention. Si la firme locale refuse la volonté du gouvernement en raison de la baisse de ses profits, celui-ci peut envisager d'autres mécanismes incitatifs. Il peut verser une subvention à la firme locale afin qu'elle réalise son profit optimal tout en absorbant la technologie nouvelle avec le niveau prédéterminé de qualité de diffusion. Le modèle sert à poser les termes du problème de diffusion. Les conclusions sont intéressantes pour ce qui concerne la stratégie des gouvernements des PVD. Ces derniers doivent sélectionner les firmes étrangères qu'il convient d'attirer en choisissant celles qui offrent le maximum de chances de diffusionThe aim of this work is to focus on developing countries access to the so-called "new" technologies. Foreign direct investment appears as the more efficient channel of technological transfer. However, technological spillovers must be of high quality in order to be of high interest. The economic literature has focus on the transfer incentives leaving on one side the problem of spillovers. The thesis fills this gap. In order to isolate the technological spillovers phenomena, we propose a model of direct vertical investment, supposing the degree of spillovers quality settled. In a first step, the host-country government proposes an "investment" premium in order to compensate location disadvantages. When endogenous spillovers of local firms are low, the government can intervene in second step fixing thus a higher predetermined quality. If the local firms refuse the previous intervention for profits reasons, the government can provide other incentives mechanism taking the form of subsides. The government proposes a subsidy to the local firm in order to induce an optimal profit meanwhile the new technology is absorbed with a high quality spillovers level. The model proposes to establish the problem generated by technological spillovers. Our conclusions are interesting concerning the leading government strategies in developing countries. They have to select foreign firms offering the best chance of technological spillovers
10
Merriam, Susan Carol. "Direct demonstration of self-similarity in a hydrodynamic treatment of polymer self-diffusion." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0501102-142449.
11
Kang, Sangwoo. "Direct sampling method in inverse electromagnetic scattering problem." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS417/document.
Анотація:
Le problème de l'imagerie non itérative dans le cadre de la diffraction électromagnétique inverse utilisant la méthode d'échantillonnage direct (DSM) est considéré. Grâce à une combinaison de l'expression asymptotique du champ proche ou du champ lointain diffracté et de l'hypothèse de petits obstacles, les expressions analytiques de la fonction d'indicateur DSM sont présentées dans diverses configurations telles que des configurations 2D/3D, mono-/multi-configurations statiques, à vue limitée/complète et fréquence unique/ diversité en fréquence. Une fois l'expression analytique obtenue, sa structure est analysée et des améliorations proposées. Notre approche est validée à l’aide de données de simulation, et d’expériences le cas échéant. Premièrement, la structure mathématique du DSM à fréquence fixe en 2D dans divers problèmes de diffusion est établie, permettant une analyse théorique de son efficacité et de ses limites. Pour surmonter les limitations connues, une méthode alternative d'échantillonnage direct (DSMA) est proposée. Puis le cas multi-fréquence est investigué en introduisant et en analysant le DSM multi-fréquence (MDSM) et le DSMA multi-fréquence (MDSMA). Enfin, notre approche est étendue aux problèmes de diffraction électromagnétique inverse 3D pour lesquels le choix de la polarisation du dipôle de test est un paramètre clé. De par notre approche analytique, ce choix peut être effectué sur la base de la polarisation du champ incidentThe non-iterative imaging problem within the inverse electromagnetic scattering framework using the direct sampling method (DSM) is considered. Thanks to the combination of the asymptotic expression of the scattered near-field or far-field and of the small obstacle hypothesis the analytical expressions of the DSM indicator function are presented in various configurations such as 2D/3D configurations and/or mono-/multi-static configurations and/or limited-/full-view case and/or mono-/multi-frequency case. Once the analytical expression obtained, its structure is analyzed and improvements proposed. Our approach is validated using synthetic data and experimental ones when available. First, the mathematical structure of DSM at a fixed frequency in 2D various scattering problems is established allowing a theoretical analysis of its efficiency and limitations. To overcome the known limitations an alternative direct sampling method (DSMA) is proposed. Next, the multi-frequency case is investigated by introducing and analyzing the multi-frequency DSM (MDSM) and the multi-frequency DSMA (MDSMA).Finally, our approach is extended to 3D inverse electromagnetic scattering problems for which the choice of the polarization of the test dipole is a key parameter. Thanks to our analytical analysis it can be made based on the polarization of the incident field
12
Hamid, Adnan. "Direct Numerical Simulation Studies of Sedimentation of Spherical Particles." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188621.
13
Olafsson, Jonas. "Antimicrobial Susceptibility Testing Directly from Urine Samples : a Comparison between Standardised and Direct Disk Diffusion Testing together with Direct Species Identification using Matrix Assisted Laser Desorption/Ionisation Time of Flight." Thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-27645.
Анотація:
Urinary tract infection (UTI) is a very common infection in humans and a majority is caused by Escherichia coli. UTI are commonly treated empirically. However, empiric treatment has become more problematic due to increased antibiotic resistance to commonly used antibiotic agents. It is therefore desirable with short turnover times for antimicrobial susceptibility testing and species identification to improve antibiotic treatment at an early stage. Matrix Assisted Laser Desorption/Ionisation Time of Flight (MALDI-TOF) can provide species identification faster than former routine methods. This study compared direct and standard susceptibility testing using disk diffusion on Enterobacteriaceae (EB) from urine samples. The possibility to standardise the inoculum for direct susceptibility testing via a pellet obtained by a series of centrifugations was also evaluated, as well as direct species identification with MALDI-TOF from the pellet. Results from direct susceptibility testing from urine samples with EB, performed either directly from the urine or with a standardised inoculum, correlated well to those obtained with standardised susceptibility testing using EUCAST disk diffusion methodology with few errors, of which most were associated with Proteus mirabilis. The concept of standardising the inoculum for direct susceptibility testing to 0.5 McFarland was labour intensive and did not improve the results further. However, direct species identification from the urine pellet using MALDI-TOF showed good correlation to routine identification. Of 238 samples, an EB was correctly identified in 148 samples using MALDI-TOF.
14
Almahasna, Shaker Hassanali A. "Foreign direct investment (FDI) as a channel of technology diffusion : the case of Saudi Arabia." Thesis, University of Newcastle upon Tyne, 2012. http://hdl.handle.net/10443/1593.
Анотація:
Countries' economies should be diversified as much as possible to avoid economic slumps. Saudi Arabia’s economy is highly dependent on oil as a major source of financial resources. However, diversification of economic activities requires improvement in the technological infrastructure of the country. FDI is considered a major source of technology diffusion. When foreign investors move some of their activities to a host country, they create externalities known as Spillovers. Spillovers are created with support of four major channels or effects, which are Demonstration-Imitation, Linkage, Competition and Workers’ Mobility. The aim of this research, hence, is to study the effects of FDI on technology diffusion in Saudi Arabia. It investigates the above mentioned four effects as channels of productivity growth and tries to analyze the spillovers resulting from foreign firms’ operations in the country. Moreover, the study tries to discover the mechanism through which FDI promotes the technology diffusion. This is done by the utilization of the Total Factor Productivity (TFP) analysis. The TFP has been utilized by previous researchers as an indicator of technology flow and separation across cities and countries. The second objective of this research is to study the local investors’ expectation of the future effects of FDI on the technology diffusion in the country. This is done by analyzing interaction between Competition and Linkages. It continues by analyzing the interaction between Training and workers’ Mobility. The third objective of this study is to provide recommendations to the Saudi Arabian General Investment Authority (SAGIA), pertinent to the development of the technology diffusion in Saudi Arabia. To achieve the above mentioned objectives a survey, composed of two parts, was developed. The first part of the survey targeted both foreign and local investors in four major geographical areas of Saudi Arabia. Those areas are the Eastern Province, Riyadh, Qassim and Hail. The second part of the survey targeted the local investors in the same geographical areas. To conduct the data analysis of the first part of the survey, a model is developed based on the Parente and Prescott equation. The data analysis of this portion is conducted using Ordinary Least Square (OLS) regression. The second part of the study is analyzed using the two way Analysis of Variance. In addition, the results of part two analysis were supported by descriptive data analysis. In the first part of study, intra- and inter-industry analyses are performed. In the Inter-Industry level; the study results reveal that there is very limited technology diffusion via the four channels and this result applies without adding control variables related to Size, Age, Location and Type of industry. If those variables are added, our variables of interest lose strength. On the Intra-Industry level, there are two (Chemical and machinery) of seven major business sectors that are not benefiting from FDI existence when it comes to advantages related to technology diffusion. None of the other five sectors, however, is fully benefiting from all the effects. In the analysis, different control variables are added to the analysis to investigate their effects. This includes the Size, Age, Location and the industrial Classification. The results of the second part of the study reveals that interaction between Linkage and Competition is not expected to cause any productivity increase in Saudi Arabia. Moreover, the interaction between Training and workers’ Mobility is not expected to lead to technology diffusion. These results are derived based on local investors’ opinion polls. The result is also supported by extensive descriptive data analysis in which comparison with previous researchers’ results is conducted. In addition, these results are supported by Chi-Square analysis for the sake of accuracy of the hypothesis testing. The research is concluded with recommendations pertinent to the development of the technology diffusion in the country. The actions that are being taken are described, based on the results of this study, Also recommendations for future studies are given at the end of the research.
15
Ghiu, Silvana Melania Stefania. "Mass Transfer of Ionic Species in Direct and Reverse Osmosis Processes." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000176.
16
Abdelaziz, Batoul. "Direct algorithms for solving some inverse source problems." Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP1956/document.
Анотація:
Cette thèse traite de problèmes inverses de sources dans deux cas : les sources fixes en 2D et 3D équations elliptiques et une source non-stationnaire dans une équation de diffusion. Dans le cadre de ce travail, nous considérons des sources ponctuelles (monopôles, dipôles et sources multipolaires) et des sources ayant support compact dans un nombre fini de petits sous-domaines qui modèlent les sources dans les problèmes EEG/MEG et le problème de tomographie par bioluminescence (BLT). Le but de cette thèse est de proposer des méthodes d’identification robustes qui permettent de déterminer leur nombre, leurs intensités et leurs positions. Des méthodes algébriques directes sont utilisées pour identifier les sources fixes et une méthode quasi-algébrique mélangée avec un problème d’optimisation est utilisé pour récupérer les sources avec des intensités variables dans le temps. Des résultats numériques sont effectués afin de mettre en évidence la robustesse de nos algorithmes d’identificationThis thesis deals with inverse source problems in 2 cases : stationary sources in 2D and 3D elliptic equations and a non-stationary source in a diffusion equation. the main form of sources considered are pointwise sources (monopoles, dipoles and multipolar sources) having compact support within a finite number of small subdomains modeling EEG/MEG problems and Bioluminescence Tomography (BLT) problems. The purpose o this thesis is mainly to propose robust identification methods that enable us to reconstruct the number, the intensity and the location of the sources. Direct algebraic methods are used to identify the stationary siurces and a quasi-algebraic method mixed with an optimieation method is employed to recover sources with time-variable intensities. Numerical results are shown to prove the robustness of our identification algorithms
17
Dawson, Craig. "Materials for direct methanol fuel cells: inhibition of methanol crossover using novel membrane electrode assemblies." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/materials-for-direct-methanol-fuel-cells-inhibition-of-methanol-crossover-using-novel-membrane-electrode-assemblies(843284c4-3620-4cac-9118-06671d7bb420).html.
Анотація:
This thesis focuses on developing an alternative system for membrane electrode assembly (MEA) formation to use with a direct methanol fuel cell (DMFC). The approach involves incorporating inorganic fillers with an industry standard Nafion polymer as part of a methanol resistant composite barrier layer at the anode/membrane interface of MEA featuring Nafion 117 membranes. This procedure is used to reduce the fuel cell losses related to the crossover of un-oxidised methanol through the membrane and prevent its subsequent reaction at the cathode. The inorganic filler used within this study was mordenite that has Si/Al ratio of 5 and by incorporating this into the barrier layer a superior DMFC performance has been achieved in comparison to a standard MEA featuring a Nafion 117 membrane. The voltage, current density and power density used as a measure of DMFC performance under a range of methanol molarities (1M-4M) and cell temperatures (40°C-70°C) have been taken for both the novel and standard MEA. Linear sweep voltammetry (LSV) and AC impedance spectroscopy (ACIS) were used to give some insight into what was occurring within the MEA with regards to methanol crossover current and the proton conductivity within the DMFC. To obtain the best possible DMFC performance a range of mordenite loadings from 0wt%1.0wt% were utilised and an optimum loading of 0.5wt% was reached. MEA which featured mordenite that had undergone ion exchange into a protonated form (from the sodium form) and had a silane functional group (glycidoxypropyltrimethoxysilane) grafted onto the surface, gave DMFC performances that were as much as 50% better than the standard. The highest power density obtained with this MEA was 43.6mW/cm-2 compared to the 35mW/cm-2 obtained using the standard. Values obtained for the methanol crossover current and proton conductivity under working DMFC operating conditions showed that this novel MEA had as much as 16% lower methanol permeability compared to the standard combined with comparable proton conductivity when using a 1M methanol feed. The durability of a novel MEA featuring the 0.5wt% functionalised H-mordenite composite barrier layer was tested in the DMFC and compared to a standard MEA at a constant current of 50mA/cm-2 over 100 hours. The cell potential fell by 0.1mV/h in comparison to a 0.23mV/h loss observed with the standard. The work reported within this study aims to show that by incorporating a thin Nafion/mordenite composite layer at the anode/membrane interface within an MEA will result in improvements in DMFC performance. The development of this technology has led to the application for a patent due to the potential for the commercial development of DMFC using this novel approach.
18
Breitwieser, Matthias, Riko Moroni, Jonathan Schock, Michael Schulz, Burkhard Schillinger, Franz Pfeiffer, Roland Zengerle, and Simon Thiele. "Water management in novel direct membrane deposition fuel cells under low humidification." Elsevier, 2016. https://publish.fid-move.qucosa.de/id/qucosa%3A72518.
Анотація:
Polymer electrolyte membrane fuel cells (PEMFCs) fabricated by direct membrane deposition (DMD) were shown to work even at dry conditions without significant deterioration of the membrane resistance. Here, in situ neutron radiography is used to investigate the water management in those fuel cells to uncover the phenomena that lead to the robust operation under low humidification. A constant level of humidification within the membrane electrode assembly (MEA) of a DMD fuel cell is observed even under dry anode operation and 15% relative humidity on the cathode side. This proves a pronounced back diffusion of generated water from the cathode side to the anode side through the thin deposited membrane layer. Over the entire range of polarization curves a very high similarity of the water evolution in anode and cathode flow fields is found in spite of different humidification levels. It is shown that the power density of directly deposited membranes in contrast to a 50 μm thick N-112 membrane is only marginally affected by dry operation conditions. Water profiles in through-plane direction of the MEA reveal that the water content in the DMD fuel cell remains steady even at high current densities. This is in contrast to the N-112 reference fuel cell which shows a strong increase in membrane resistance and a reduced MEA water content with raising current densities. Thus this new MEA fabrication technique has a promising perspective, since dry operation conditions are highly requested in order to reduce fuel cell system costs.
19
Pianese, Fabio. "Systèmes pair à pair pour la diffusion de données vidéo : PULSE, un système adaptatif pour le streaming en direct sur Internet." Nice, 2007. http://www.theses.fr/2007NICE4058.
Анотація:
Le live streaming consiste en la distribution d’un flux de données multimédias (vidéo et audio) en direct vers une large audience par le biais d’un réseau d’ordinateurs. L’approche traditionnelle client-serveur souffre d’un goulot d’étranglement au niveau de la bande passante remontante du serveur, dont la consommation augmente de façon linéaire avec le nombre d’usagers. Une approche pair-à-pair (P2P) a l’énorme avantage de permettre le passage à l’échelle du système jusqu’à une taille arbitraire, puisque chaque nœud qui reçoit le flux vidéo peut apporter ses ressources au réseau au même temps qu’il en consomme. En théorie, au cas où chaque nœud apporterait en moyenne la même quantité d’upload qu’il consomme, le système pourrait s’accroître indéfiniment. Ce travail présente et évalue les performances de PULSE, un système de streaming en direct adapté aux exigences pratiques d’un déploiement à large échelle sur l’Internet. PULSE utilise un réseau maillé non structuré et applique des mécanismes locaux d’incitation au partage en tant que critères pour le choix des nœuds avec qui établir des associations. L’aspect le plus innovant de PULSE est l’introduction d’un mécanisme qui combine l’incitation avec une boucle de rétroaction basée sur les délais de réception, qui mène à la formation de clusters parmi les nœuds qui partagent la même quantité de ressources. Exploitant cette organisation émergente et utilisant des mesures de latence de bout en bout pour estimer la proximité entre nœuds, PULSE peut supporter un large éventail de scénarios réels où les ressources sont rares et distribuées de façon hétérogène, avec une large population d’usagers au comportement dynamiqueLive Streaming consists in distributing live media (video and audio) to large audiences over a computer network. The traditional client-server approach to live streaming has a serious scalability limit, as the upload capacity requirement at the server grows linearly with the user population. A P2P solution has the big advantage of seamlessly scaling to arbitrary population sizes, as every node that receives the video, while consuming resources, can at the same time offer its own upload bandwidth to serve other nodes. In theory, if every node contributed on average at least as much as it consumed, the P2P system would have enough resources to grow indefinitely. This work presents and evaluates PULSE, a practical P2P live streaming system intended for large-scale deployment over the Internet. PULSE uses an unstructured mesh-based design and relies on local pairwise incentives as its peer selection mechanism. The most innovative feature of PULSE is the unique coupling of incentives with feedback derived from data reception, which leads to the emergence of clusters that regroup nodes with similar resources. By exploiting this intrinsic clustering phenomenon and by leveraging latency measurements to estimate network locality, PULSE is capable to successfully operate in a wide range of resource-constrained real world scenarios and to support dynamic user populations and heterogeneous node upload capacities
20
Khakdaman, Hamidreza. "A Two Dimensional Model of a Direct Propane Fuel Cell with an Interdigitated Flow Field." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22732.
Анотація:
Increasing environmental concerns as well as diminishing fossil fuel reserves call for a new generation of energy conversion technologies. Fuel cells, which convert the chemical energy of a fuel directly to electrical energy, have been identified as one of the leading alternative energy conversion technologies. Fuel cells are more efficient than conventional heat engines with minimal pollutant emissions and superior scalability. Proton Exchange Membrane Fuel Cells (PEMFCs) which produce electricity from hydrogen have been widely investigated for transportation and stationary applications.
The focus of this study is on the Direct Propane Fuel Cell (DPFC), which belongs to the PEMFC family, but consumes propane instead of hydrogen as feedstock. A drawback associated with DPFCs is that the propane reaction rate is much slower than that of hydrogen. Two ideas were suggested to overcome this issue: (i) operating at high temperatures (150-230oC), and (ii) keeping the propane partial pressure at the maximum possible value. An electrolyte material composed of zirconium phosphate (ZrP) and polytetrafluoroethylene (PTFE) was suggested because it is an acceptable proton conductor at high temperatures. In order to keep the propane partial pressure at the maximum value, interdigitated flow-fields were chosen to distribute propane through the anode catalyst layer.
In order to evaluate the performance of a DPFC which operates at high temperature and uses interdigitated flow-fields, a computational approach was chosen. Computational Fluid Dynamics (CFD) was used to create two 2-D mathematical models for DPFCs based on differential conservation equations. Two different approaches were investigated to model species transport in the electrolyte phase of the anode and cathode catalyst layers and the membrane layer. In the first approach, the migration phenomenon was assumed to be the only mechanism of proton transport. However, both migration and diffusion phenomena were considered as mechanisms of species transport in the second approach. Therefore, Ohm's law was used in the first approach and concentrated solution theory (Generalized Stefan-Maxwell equations) was used for the second one. Both models are isothermal.
The models were solved numerically by implementing the partial differential equations and the boundary conditions in FreeFEM++ software which is based on Finite Element Methods. Programming in the C++ language was performed and the existing library of C++ classes and tools in FreeFEM++ were used. The final model contained 60 pages of original code, written specifically for this thesis.
The models were used to predict the performance of a DPFC with different operating conditions and equipment design parameters. The results showed that using a specific combination of interdigitated flow-fields, ZrP-PTFE electrolyte having a proton conductivity of 0.05 S/cm, and operating at 230oC and 1 atm produced a performance (polarization curve) that was (a) far superior to anything in the DPFC published literature, and (b) competitive with the performance of direct methanol fuel cells. In addition, it was equivalent to that of hydrogen fuel cells at low current densities (30 mA/cm2).
21
Song, Qingsheng. "Development of Dual Gas Diffusion-Type Biofuel Cells on the Basis of Electrochemical Understanding of Enzyme-Modified Electrodes." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225650.
Анотація:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第20425号
農博第2210号
新制||農||1047(附属図書館)
学位論文||H29||N5046(農学部図書室)
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 加納 健司, 教授 宮川 恒, 教授 三芳 秀人
学位規則第4条第1項該当
22
Carvalho, Flavia Pereira de. "Investimento direto estrangeiro e transbordamentos tecnologicos : conceitos e fatores determinantes." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287632.
Анотація:
Orientadores: Sergio Robles Reis de Queiroz, Ionara da CostaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias
Made available in DSpace on 2018-08-05T05:23:11Z (GMT). No. of bitstreams: 1 Carvalho_FlaviaPereirade_M.pdf: 610006 bytes, checksum: 894bd6020abdf7c46e94513971a72d7e (MD5) Previous issue date: 2005
Resumo: O objetivo do trabalho é discutir os fatores determinantes dos transbordamentos tecnológicos - os chamados spillovers - oriundos do investimento direto estrangeiro (IDE). Num primeiro momento, faz-se uma síntese do conceito, com base nas visões, nem sempre convergentes, apresentadas pela literatura consultada. A partir dessa conceitualização inicial, são analisados de forma detalhada os mecanismos por meio dos quais o fenômeno se manifesta na economia receptora do IDE. Num segundo momento, o trabalho procura levantar os fatores que determinam a ocorrência e a magnitude do spillover, considerando a particularidade de cada caso. Tais fatores estão relacionados ora com características específicas do IDE, ora com aspectos inerentes ao ambiente onde o investimento se instala. A importância dessa diferenciação reside na necessidade de compreender porque os transbordamentos tecnológicos não se manifestam de maneira uniforme em todas as localidades. Esse debate permanece em aberto na literatura, pois os métodos de análise, em sua maioria quantitativos, não esclarecem a questão. Por fim, estabelece-se uma discussão sobre a efetividade de políticas e ações governamentais de atração IDEs com maiores probabilidades de ocorrência de spillovers, partindo das evidências obtidas na análise dos fatores determinantes do fenômeno em estudo. A conclusão do trabalho é que a ocorrência de spillovers tecnológicos não é automática, predeterminada pela presença das EMNs. As capacidades acumuladas pela economia local são determinantes para que o conhecimento disponibilizado seja efetivamente absorvido pelos agentes; além disso, o IDE intensivo em atividades tecnológicas tende a criar maiores possibilidades de geração de spillovers. Em decorrência disso, políticas que queiram gerar maiores benefícios sob a forma de transbordamentos devem considerar esses aspectos, agindo em busca da ampliação de capacidades e focando na atração de investimentos com atividade inovadora interna
Abstract: The aim of this dissertation is to discuss the determinants of technological spillovers generated by foreign direct investment (FDI). There are many, and often opposing, definitions and views concerning the concept of technological spillovers in the literature. For this reason, the first objective is to review the literature and to strive to synthesize the plurality of views available. Having done that, the work proceeds to discuss in depth the mechanisms through which spillovers take place in the host economy of the FDI. In particular, the determining factors of the occurrence and the extent of technological spillovers in specific situations. These factors are closely related to the characteristics of the FDI and also to peculiar aspects of the host economy. The discussion of the determinants is of utmost importance to help the comprehension of why spillovers happen in certain situations and not in others. The traditional approaches to the matter (most of the time econometric models) fail to shed light on such issues. In conclusion, we summarize the previous questions and analyze if government policies are capable of influencing and facilitating the incidence of technological spillovers
Mestrado
Politica Cientifica e Tecnologica
Mestre em Política Científica e Tecnológica
23
Salmela, Markus, and Rickard Ström. "Implementing Automated Trading Systems in The Swedish Financial Industry : Establishing a Framework for Successful Diffusion." Thesis, Jönköping University, JIBS, EMM (Entrepreneurship, Marketing, Management), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-12641.
Анотація:
Purpose: Our main purpose is to explore, describe and analyze the organizational conduct when implementing automated trading systems (ATS) in companies, investigate the organizational challenges arising from this, and the effects these have on a successful diffusion. As the extent of implementing ATS in the Swedish financial industry has not been explored to any greater extent, it is therefore also imperative to explore this; which will be seen as a secondary purpose to this article. Background: The study is based on innovation and diffusion theories, as well as those of power structures and organization. Further, an explanation of ATS and its dynamics is provided and discussed to facilitate a definition of the term. Method: The research has been carried out as an exploratory, descriptive and analytical qualitative study. We have conducted case studies of 7 companies that are implementing, or evaluating the implementation, of ATS. The data was collected through interviews. Conclusion: The majority of the case companies are in the clarifying and routinizing stages of the innovation process. What is found unique with ATS is that it can be implemented partly. The dimensions found central to a smooth diffusion in the companies are the required level of competence-sharing and complexity of implementation.
24
Nguyen, Thi Phong. "Direct and inverse solvers for scattering problems from locally perturbed infinite periodic layers." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX004/document.
Анотація:
Nous sommes intéressés dans cette thèse par l'analyse de la diffraction directe et inverse des ondes par des couches infinies périodiques localement perturbées à une fréquence fixe. Ce problème a des connexions avec le contrôle non destructif des structures périodiques telles que des structures photoniques, des fibres optiques, des réseaux, etc. Nous analysons d'abord le problème direct et établissons certaines conditions sur l'indice de réfraction pour lesquelles il n'existe pas de modes guidés. Ce type de résultat est important car il montre les cas pour lesquels les mesures peuvent être effectuées par exemple sur une couche au dessus de la structure périodique sans perdre des informations importantes dans la partie propagative de l'onde. Nous proposons ensuite une méthode numérique pour résoudre le problème de diffraction basée sur l'utilisation de la transformée de Floquet-Bloch dans les directions de périodicité. Nous discrétisons le problème de manière uniforme dans la variable de Floquet-Bloch et utilisons une méthode spectrale dans la discrétisation spatiale. La discrétisation en espace exploite une reformulation volumétrique du problème dans une cellule (équation intégrale de Lippmann-Schwinger) et une périodisation du noyau dans la direction perpendiculaire à la périodicité. Cette dernière transformation permet d'utiliser des techniques de type FFT pour accélérer le produit matrice-vecteur dans une méthode itérative pour résoudre le système linéaire. On aboutit à un système d'équations intégrales couplées (à cause de la perturbation locale) qui peuvent être résolues en utilisant une décomposition de Jacobi. L'analyse de la convergence est faite seulement dans le cas avec absorption et la validation numérique est réalisées sur des exemples 2D. Pour le problème inverse, nous étendons l'utilisation de trois méthodes d'échantillonnage pour résoudre le problème de la reconstruction de la géométrie du défaut à partir de la connaissance de données mutistatiques associées à des ondes incidentes planes en champ proche (c.à.d incluant certains modes évanescents). Nous analysons ces méthodes pour le problème semi-discrétisée dans la variable Floquet-Bloch. Nous proposons ensuite une nouvelle méthode d'imagerie capable de visualiser directement la géométrie du défaut sans savoir ni les propriétés physiques du milieux périodique, ni les propriétés physiques du défaut. Cette méthode que l'on appelle imagerie-différentielle est basée sur l'analyse des méthodes d'échantillonnage pour un seul mode de Floquet-Bloch et la relation avec les solutions de problèmes de transmission intérieurs d'un type nouveau. Les études théoriques sont corroborées par des expérimentations numériques sur des données synthétiques. Notre analyse est faite d'abord pour l'équation d'onde scalaire où le contraste est sur le terme d'ordre inférieur de l'opérateur de Helmholtz. Nous esquissons ensuite l'extension aux cas où la le contraste est également présent dans l'opérateur principal. Nous complémentons notre travail par deux résultats sur l'analyse du problème de diffraction pour des matériaux périodiques ayant des indices négatifs. Nous établissons en premier le caractère bien posé du problème en 2D dans le cas d'un contraste est égal à -1. Nous montrons également le caractère Fredholm de la formulation Lipmann-Schwinger du problème en utilisant l'approche de T-coercivité dans le cas d'un contraste différent de -1We are interested in this thesis by the analysis of scattering and inverse scattering problems for locally perturbed periodic infinite layers at a fixed frequency. This problem has connexions with non destructive testings of periodic media like photonics structures, optical fibers, gratings, etc. We first analyze the forward scattering problem and establish some conditions under which there exist no guided modes. This type of conditions is important as it shows that measurements can be done on a layer above the structure without loosing substantial informations in the propagative part of the wave. We then propose a numerical method that solves the direct scattering problem based on Floquet-Bloch transform in the periodicity directions of the background media. We discretize the problem uniformly in the Floquet-Bloch variable and use a spectral method in the space variable. The discretization in space exploits a volumetric reformulation of the problem in a cell (Lippmann-Schwinger integral equation) and a periodization of the kernel in the direction orthogonal to the periodicity. The latter allows the use of FFT techniques to speed up Matrix-Vector product in an iterative to solve the linear system. One ends up with a system of coupled integral equations that can be solved using a Jacobi decomposition. The convergence analysis is done for the case with absorption and numerical validating results are conducted in 2D. For the inverse problem we extend the use of three sampling methods to solve the problem of retrieving the defect from the knowledge of mutistatic data associated with incident near field plane waves. We analyze these methods for the semi-discretized problem in the Floquet-Bloch variable. We then propose a new method capable of retrieving directly the defect without knowing either the background material properties nor the defect properties. This so-called differential-imaging functional that we propose is based on the analysis of sampling methods for a single Floquet-Bloch mode and the relation with solutions toso-called interior transmission problems. The theoretical investigations are corroborated with numerical experiments on synthetic data. Our analysis is done first for the scalar wave equation where the contrast is the lower order term of the Helmholtz operator. We then sketch the extension to the cases where the contrast is also present in the main operator. We complement our thesis with two results on the analysis of the scattering problem for periodic materials with negative indices. Weestablish the well posedness of the problem in 2D in the case of a contrast equals -1. We also show the Fredholm properties of the volume potential formulation of the problem using the T-coercivity approach in the case of a contrast different from -1
25
Rózek, Aleksandra. "Direct formulation of solid foods with grape phenolics: studies on mass transfer and antioxidant capacity." Doctoral thesis, Universitat Rovira i Virgili, 2009. http://hdl.handle.net/10803/8568.
Анотація:
El enriquecimiento de frutas y verduras con minerales, vitaminas o compuestos fisiológicamente activos de los que se deriven efectos potencialmente beneficiosos para la salud y la prevención de enfermedades, puede resultar crucial en el desarrollo de nuevos alimentos funcionales. Recientemente, los extractos de semillas y piel de uva se han convertido en un complemento nutricional muy extendido debido a su elevado contenido en compuestos fenólicos. Estos compuestos han mostrado ser altamente biodisponibles además de conferir excelentes beneficios para la salud. En los últimos años, la aplicación del tratamiento osmótico (TO) se ha propuesto como un método eficaz de introducir en el alimento cantidades controladas de los solutos presentes en la solución osmótica, deshidratándolo parcialmente.Un rango de alimentos sólidos enriquecidos con compuestos fenólicos de uva de diferentes fuentes fueron formulados mediante TO. Parámetros de proceso como la fuente y concentración de los compuestos fenólicos, la naturaleza y concentración de soluto osmo-activo en la solución osmótica, y la estructura del alimento fueron investigados. Además el efecto de un post-tratamiento tal como el secado convectivo en la estabilidad y la capacidad antioxidante de fenólicos de uva impregnados en el alimento tratado osmóticamente fue estudiado.
Los resultados confirman que TO es la tecnología adecuada para explotación de geles alimenticios, frutas y verduras como matrices en las cuales los ingredientes funcionales pueden ser incorporados con éxito para proporcionar productos funcionales de humedad intermedia. El mosto concentrado de uva y extractos comerciales de semilla de uva y orujo de uva blanca fueron utilizados como suplementos nutricionales. Su alto contenido en compuestos fenólicos los hacen una fuente ideal de antioxidantes naturales.
The enrichment of fruits and vegetables with minerals, vitamins or physiologically active compounds that have potential benefits in terms of health maintenance and disease prevention may be a crucial way of developing new functional foods. Recently, extracts from grape seeds and skins have become a widespread nutritional supplement, because of their high content of phenolic compounds. These compounds have been shown to be highly bioavailable and to provide excellent health benefits. In the last few years, it has been suggested that osmotic treatment (OT) is a useful way of introducing controlled quantities of solution solutes into food and partially dehydrating it at the same time.
A range of solid foods enriched with grape phenolics from several sources were formulated using OT. Process parameters such as the source and concentration of the phenolic compounds, the nature and concentration of the osmo-active solute in the osmotic solution, and the food structure were investigated. Moreover the effect of a post treatment such as convective air drying on the stability and antioxidant properties of the grape phenolics infused in the osmo-treated food was studied.
The results confirm that OT is a suitable technology for the exploitation of jelly foods, fruits and vegetables as matrices into which functional ingredients can be successfully incorporated to provide novel functional products of intermediate moisture. Concentrated red grape must and commercial grape seed and white grape marc extracts were successfully used as nutritional supplements. Their high content in phenolic compounds makes them ideal sources of natural antioxidants.
26
Olina, Bassala Jean-Paul. "Le semis direct sans labour et avec utilisation des herbicides dans la zone cotonnière au Nord Cameroun : diffusion, impacts agronomiques et socio-économiques d'une innovation en pleine expansion." Toulouse 2, 2010. http://www.theses.fr/2010TOU20027.
Анотація:
Pour mieux comprendre les stratégies des agriculteurs à travers leurs pratiques et, comparer les performances économiques du semis direct avec herbicides par rapport au labour, une recherche a été conduite dans les villages de Mafa kilda et de Pandjama au Nord Cameroun. La méthodologie a consisté à adopter une approche compréhensive pour mieux comprendre le sens des pratiques des agriculteurs. Nous avons analysé les représentations sociales qu’ils ont de leur métier, de la pratique de semis direct avec herbicides et de la pratique de labour. L’analyse porte sur leurs motivations, leurs perceptions des risques sur l’environnement et sur la santé, liées à l’usage des herbicides. Un suivi technico-économique des exploitations pour les deux systèmes de culture a été réalisé. L’analyse factorielle de correspondance (AFC) a permis de déterminer une typologie des exploitations. Une simulation économique a été faite. L’analyse montre que la mise en place des cultures varie de 0. 7 hj/ha à 1. 6 hj/ha sur semis direct contre 4 à 5 hj/ha sur labour. Ce gain de temps sur semis direct peut varier de 60 à 80 % selon les cultures. La productivité du travail et le revenu familial sont supérieurs dans les exploitations en semis direct par rapport au labour. La simulation montre que, en combinant une lutte chimique modérée avec un sarclage précoce en traction animale, on peut obtenir une marge brute acceptable sur semis direct avec herbicides pour les cultures du coton, du maïs et d’arachide. Le capital social et culturel permet à 70 et 90 % des agriculteurs respectivement à Mafa kilda et à Pandjama, d’avoir une perception et une prise de conscience des risques liés à l’usage des herbicidesIn order to better understand the strategies used by farmers in chemical weed control and with the aim of comparing the economic returns of direct sowing and herbicide application with tillage, a research was conducted in two benchmark villages (Mafa Kilda and Pandjama) in North Cameroon. Comprehensive approach was adopted in order to better understand farmers practically minded. Farmer’s social representations of their profession about direct sowing with herbicides and till practice have been analysis. An analysis concerned the reasons for adoption of direct sowing and herbicide use by farmers, and farmer’s perception of the health and environmental risks. A follow-up technico-economic study of the two farming system was undertaken. The factorial correspondence analysis was used to analyse the typology of farms. Economical analysis was employed. Results show that with direct sowing 0. 7 man-days/ha and 1. 6 man-days/ha are required to establish crops in the field whereas with regular tillage 4 to 5 man-days/ha are required. This gain in time with direct sowing can vary between 60 to 80% depending on the crop. The productivity and revenue from farms under direct sowing and herbicide application are higher compared with tillage. For cotton, maize and groundnut cultivation, the application of a medium dosage of herbicide combined with early weeding using animal traction, can permit to have acceptable profit margin with direct sowing and herbicide application. Due to social and cultural capital differences, 94 % of farmers at Pandjama were aware of the potential health and environmental hazards related to heavy use of herbicides, compared to 70 % at Mafa Kilda
27
Westman, Natalee. "Direktresistensbestämning för blododlingar : Volymoptimering och reproducerbarhet." Thesis, Jönköping University, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-53082.
Анотація:
Direct antimicrobial susceptibility testing (dAST) is not a standardized method and there is no recommendations regarding the volume of blood culture media to be used. The aim of the study was to optimize the method of dAST by determining a volume of blood culture media in µL to be used and to test the reproducibility of the volume optimized method. The dASTs (n=160) were performed on blood culture bottles (n=40) inoculated with reference bacteria (n=4), using four test volumes (50 µL, 75 µL, 100 µL and 125 µL). The optimized method was implemented on frozen and fresh bacterial isolates (n=120) derived from blood cultures. Susceptibility tests according to EUCASTs method for disk diffusion was also performed. Deviations in SIR-categorical agreement was calculated. The optimal volume of blood culture media for dAST was 75 µL. All dASTs were approved for three out of four reference bacteria whereas for the fourth reference bacteria eight out of ten dASTs was approved. Testing the reproducibility, the optimized method showed a sensitivity and specificity of 100 %. No deviation in categorical agreement of SIR-categorization was observed. The result shows a possibility of implementing a standardized method for dAST regarding the volume of blood culture media.Vid direktresistensbestämning används blododlingsmedium för tillverkning av bakteriesuspensioner. Metoden är inte standardiserad och det finns ingen rekommenderad volym blododlingsmedium som bör användas. Syftet med studien var att optimera metoden för direktresistensbestämning genom att bestämma en volym blododlingsmedium i µL som används för tillverkning av bakteriesuspensioner. Den optimerade metodens prestanda utvärderades därefter på kliniska patientisolat. Metoden optimerades genom att direktresistensbestämningar (n=160) utfördes baserat på fyra volymer (50 µL, 75 µL, 100 µL och 125 µL) blododlingsmedium (n=40), som var inokulerade med fyra olika referensstammar. Den optimerade metodens reproducerbarhet testades på frysta och färska patientisolat (n=120) genom jämförelse av SIR-kategorisering mellan direktresistensbestämning samt resistensbestämning enligt EUCASTs metod för diskdiffusion. Den optimala volymen blododlingsmedium med kända referensstammar fastställdes vara 75 µL då samtliga direktresistensbestämningar godkändes för tre av fyra referensstammar, för den fjärde referensstammen godkändes åtta av tio. Då metoden implementerades på kliniska patientisolat från positiva blododlingar var känsligheten och specificiteten 100 % avseende kategorisk överensstämmelse enligt SIR-systemet. Inga avvikelser avseende SIR-kategorisering observerades. Resultaten visar att det är möjligt att optimera metoden avseende volymen blododlingsmedium som används för direktresistensbestämning på blododlingsflaskor. Då den optimerade metodens känslighet och specificitet var 100 %, är det möjligt att implementera metoden i rutinarbetet.
28
Artz, Matthew. "An Ethnography of Direct-to-Consumer Genomics [DTCG]: Design Anthropology Insights for the Product Management of a Disruptive Innovation." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248393/.
Анотація:
Direct-to-consumer genomics (DTCG) health testing offers great promise to humanity, however to date adoption has lagged as a result of consumer awareness, understanding, and previous government regulations restricting DTCG companies from providing information on an individual's genetic predispositions. But in 2017 the broader DTCG market which also includes genealogical testing demonstrated exponential growth, implying that DTCG is starting to diffuse as an innovation. To better understand the sociocultural forces affecting diffusion, adoption, and satisfaction, qualitative ethnographic research was conducted with DTCG genealogy and health consumers. The data was qualitatively analyzed using thematic analysis to understand the similarities and differences in beliefs, attitudes, intentions, and mediating factors that have influenced consumers. Design anthropology theory and methods were used to produce ethnographically informed insights. The insights were then translated into actionable product management and business strategy recommendations.
29
Mukherjee, Sayak. "Applications of Field Theory to Reaction Diffusion Models and Driven Diffusive Systems." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/39293.
Анотація:
In this thesis, we focus on the steady state properties of two systems which are genuinely out of equilibrium. The first project is an application of dynamic field theory to a specific non equilibrium critical phenomenon, while the second project involves both simulations and analytical calculations. The methods of field theory are used on both these projects. In the first part of this thesis, we investigate a generalization of the well-known field theory for directed percolation (DP). The DP theory is known to describe an evolving population, near extinction. We have coupled this evolving population to an environment with its own nontrivial spatio-temporal dynamics. Here, we consider the special case where the environment follows a simple relaxational (model A) dynamics. We find two marginal couplings with upper critical dimension of four, which couple the two theories in a nontrivial way. While the Wilson-Fisher fixed point remains completely unaffected, a mismatch of time scales destabilizes the usual DP fixed point. Some open questions and future work remain.
In the second project, we focus on a simple particle transport model far from equilibrium, namely, the totally asymmetric simple exclusion process (TASEP). While its stationary properties are well studied, many of its dynamic features remain unexplored. Here, we focus on the power spectrum of the total particle occupancy in the system. This quantity exhibits unexpected oscillations in the low density phase. Using standard Monte Carlo simulations and analytic calculations, we probe the dependence of these oscillations on boundary effects, the system size, and the overall particle density. Our simulations are fitted to the predictions of a linearized theory for the fluctuation of the particle density. Two of the fit parameters, namely the diffusion constant and the noise strength, deviate from their naive bare values [6]. In particular, the former increases significantly with the system size. Since this behavior can only be caused by nonlinear effects, we calculate the lowest order corrections in perturbation theory. Several open questions and future work are discussed.Ph. D.
30
Bonneau-Crépin, Charlotte. "Les pratiques de réception comme marques de capital symbolique : le cas du mass-streaming chez les fans de musique populaire coréenne." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66325.
Анотація:
Les transformations engendrées par l’avènement des réseaux sociaux et des plateformes d’écoute musicale numériques ont vu naître de nouvelles pratiques de réception musicale. Ce mémoire de maîtrise porte sur l’une d’entre elles, exclusive aux admirateurs de musique populaire coréenne. Plus précisément, il traite d’une activité inédite du nom de mass-streaming, populaire au sein de la communauté d’admirateurs de K-pop (Korean Pop). Cette pratique consiste en l’utilisation de méthodes visant à faire augmenter le plus rapidement possible le nombre de lectures associées à une chanson sur les plateformes d’écoute musicale numériques. L’objectif de ce mémoire est de déterminer la mesure dans laquelle le mass-streaming influe sur l’industrie musicale et les admirateurs qui s’y adonnent. Plusieurs modèles théoriques sont employés afin de formuler une réponse à ce questionnement, notamment ceux des mondes de l’art (Becker 1984), de capital symbolique (Bourdieu 1994) et de capital sous-culturel (Thornton 2013). En guise d’étude de cas, c’est le boyband coréen Beyond The Scene (BTS) et sa communauté de fans qui sont observés. La collecte d’informations a été effectuée en deux phases. La première, qui s’est déroulée entièrement sur Twitter, a consisté en la création d’une collection de tweets sur le sujet du mass-streaming rédigés par des admirateurs. La seconde a été la tenue d’entrevues individuelles semi-dirigées avec des professionnels de l’industrie musicale. Afin de présenter un portrait complet du mass-streaming, une description du contexte historique menant à son avènement est effectuée, de même que la présentation des méthodes employées par les admirateurs ainsi que les causes de l’existence du mass-streaming. Finalement, les différents impacts de la pratique sont envisagés en tant que différents types de capital symbolique (économique, social, culturel, sous-culturel) afin de représenter le plus fidèlement possible les répercussions de cette activité sur les différents partis qui y sont impliqués.The transformations brought upon by the rise of social networks and music streaming platforms have caused the birth of new ways to consume music. This thesis is about one of them, exclusive to fans of Korean popular music. More precisely, it is about a novel activity called mass-streaming, popular amongst the K-pop (Korean Pop) fan community. This practice consists in the use of specific methods that are geared towards the quickest rise possible in streams associated to a particular song on streaming platforms. The aim of this thesis is to determine the measure in which mass-streaming has an influence on the music industry and the fan community. Different conceptual models are applied in order to formulate an answer to that question, namely those of Monde des Arts (Becker 1984), symbolic capital (Bourdieu 1994) and subcultrual capital (Thornthon 2013). As a case study, it is Korean boyband Beyond The Scene (BTS) and its fan community that are studied. Data collection took place in two distinct phases. The first, which took place entirely on microblogging site Twitter, consisted in the creation of a collection of tweets about mass-streaming. The second was made up of a series of semi-directed interviews with music industry professionals. In order to present a complete picture of what mass-streaming is, a description of the historic context and causes that lead to its emergence is made, as well as the presentation of the methods used by fans. Finally, the different impacts of the studied practice are considered as different types of symbolic capital (economic, social, cultural, subcultural) in order to represent as precisely as possible the potential repercussions of this new practice on all parties involved in its functioning.
31
Hoang, Vu Dinh. "Charge transport study of InGaAs two-color QWIPs." Thesis, Monterey California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1574.
Анотація:
Approved for public release, distribution is unlimitedIn this thesis, a series of experiments were performed to characterize the material properties of InGaAs/GaAs for use in a two-color quantum-well IR photodetector (QWIP) design. Results from room temperature studies using cathodoluminescence and photoluminescence indicated light emission at 858 nm and 1019 nm from GaAs and InGaAs, respectively. Using a direct transport imaging technique, an edge dislocation pattern was observed and shown to be confined to the InGaAs layer of the material. A dislocation density measurement was performed and was shown to be less than 2000 lines/cm. Quantitative intensity level measurements indicated fluctuation in the region of dislocations to be less than 30% of the signal to background level. Finally, a spot mode study using the direct transport imaging method was performed to evaluate the feasibility of using this technique for contact-less diffusion length measurements.
Civilian, Department of Air Force
32
Mechhoud, Sarah. "Estimation de la diffusion thermique et du terme source du modèle de transport de la chaleur dans les plasmas de tokamaks." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00954183.
Анотація:
Cette thèse porte sur l'estimation simultanée du coefficient de diffusion et du terme source régissant le modèle de transport de la température dans les plasmas chauds. Ce phénomène physique est décrit par une équation différentielle partielle (EDP) linéaire, parabolique du second-ordre et non-homogène, où le coefficient de diffusion est distribué et le coefficient de réaction est constant. Ce travail peut se présenter en deux parties. Dans la première, le problème d'estimation est traité en dimension finie ("Early lumping approach"). Dans la deuxième partie, le problème d'estimation est traité dans le cadre initial de la dimension infinie ("Late lumping approach"). Pour l'estimation en dimension finie, une fois le modèle établi, la formulation de Galerkin et la méthode d'approximation par projection sont choisies pour convertir l'EDP de transport en un système d'état linéaire, temps-variant et à entrées inconnues. Sur le modèle réduit, deux techniques dédiées à l'estimation des entrées inconnues sont choisies pour résoudre le problème. En dimension infinie, l'estimation en-ligne adaptative est adoptée pour apporter des éléments de réponse aux contraintes et limitations dues à la réduction du modèle. Des résultats de simulations sur des données réelles et simulées sont présentées dans ce mémoire.
33
Caro, Gregory P. "Direct numerical simulations of diffusive staircases in the Arctic." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Mar/09Mar%5FCaro.pdf.
Анотація:
Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, March 2009.Thesis Advisor(s): Radko, Timour. "March 2009." Description based on title screen as viewed on April 23, 2009. Author(s) subject terms: Double-diffusion, diffusive convection, heat flux, thermohaline staircase, Includes bibliographical references (p. 39-41). Also available in print.
34
Lansky, Zdenek, Marcus Braun, Wolde Pieter Rein ten, Marcel E. Janson, and Stefan Diez. "Diffusible crosslinkers generate directed forces in microtubule networks." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-182658.
35
Klumpp, Stefan. "Movements of molecular motors : diffusion and directed walks." Phd thesis, [S.l. : s.n.], 2003. http://pub.ub.uni-potsdam.de/2003/0020/klumpp.pdf.
36
Benamar, Rajae. "Etude fréquentielle de l'admittance d'une hétérojonction Ga0, 6Al0, 4As(P)/Ga0,2Al0,8As(N) sous polarisation directe." Poitiers, 1994. http://www.theses.fr/1994POIT2281.
Анотація:
Ce memoire concerne la caracterisation electrique par l'etude frequentielle de l'admittance d'une diode electroluminescente ga#0#,#6al#0#,#4as(p)/ga#0#,#2al#0#,#8as(n) emettant dans le rouge. Les mesures sont effectuees sous polarisation directe, a la temperature ambiante pour des frequences variant entre 1 mhz et 40 mhz. Cette etude a pour but de mettre en evidence la contribution des defauts lies a un accord de maille imparfait dans ces structures. L'extension du modele de shockley aux heterojonctions a permis de calculer l'admittance liee aux phenomenes de diffusion. Cependant les resultats theoriques obtenus sont en desaccord avec les resultats experimentaux qui revelent des pics de susceptance n'existant pas dans le modele de diffusion. Le calcul de l'admittance avec prise en compte d'un niveau discret de pieges a l'interface conduit a l'existence d'un maximum local pour la susceptance. Par contre, l'hypothese de plusieurs niveaux d'energie etendus a la zone de charge d'espace presente une croissance monotone de la susceptance. La concordance du comportement theorique et experimental conduit donc a supposer la presence des niveaux discrets de pieges d'interface qui s'ajoutent aux phenomenes de diffusion. Ces niveaux sont a l'origine des phenomenes de degradation et limitent les performances de ces composants
37
af, Geijerstam Jan. "Landscapes of Technology Transfer : Swedish Ironmakers in India 1860–1864." Doctoral thesis, KTH, Industrial Economics and Management, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3784.
Анотація:
In the early 1860s three Swedes, Nils Wilhelm Mitander,Julius Ramsay and Gustaf Wittenström, were engaged by theBritish to build and run charcoal-based ironworks in India.These works, the Burwai Iron Works of the British Government inthe case of Mitander and the privately owned Kumaon Iron Worksin the case of Ramsay and Wittenström, were both to bebased on the most modern European technology. The projects werepioneering in Indian ironmaking. The ambitions were high andstakes big, but after only a few years the projects were closedand the Swedes returned home.Landscapes of Technology Transferpresents a detailedstudy of the Kumaon and Burwai Iron Works, from their firstconception to their final closure. The investigation isbasically empirical and a fundamental question is: Why were theworks never brought into full and continuous production?
The ironworks projects should be considered as processes oftechnology transfer rather than fully fledged and completedtransfers. In spite of this lack of success, or maybe becauseof it, the history of the ironworks and the Swedes also forms afruitful case to put other questions of wide relevance. Itexposes workings and effects of colonialism and offers anexplanation of the late development of India's iron and steelindustry and analyses of the complex totality forming theprerequisites for a successful transfer of technology. The longtraditions of bloomery ironmaking in India and ismarginalisation is also discussed.
Landscapes of Technology Transferis a comprehensiveempirical study. From a local and individual perspective ittraces lines of connection across boundaries of time andgeography. The historical landscapes of technology transfer aredescribed in their cultural, social, economic and politicaldimensions and the thesis underlines the importance of a closeacquaintance with local settings and conditions, where historyis manifested in a physical presence. The remains of theironworks and theirlocal landscapes in present-day India areused as a central source for writing their histories. There isalso a strong emphasis on the use of photographs and drawingsas sources.
The outcome of the projects was the result of the interplaybetween the local and the global, between a diversity ofconcrete factors influencing the construction of the works andtheir running and their colonial character. The studyemphasises the importance of technological systems andnetworks, both on a micro and a macro level. On a local leveldemanding logistics, a sometimes adverse climate, theprocurement of charcoal and iron ore in sufficient quantitiesand the build up of knowledge of ironmaking posed serious butnot insurmountable difficulties. Most obstacles were overcomealready during the first few years of the 1860s, the period ofthe Swedes, but to put the works into full and continuousproduction would have needed perseverance and purposefulefforts to support and protect the iron production, at leastduring an initial period. In the end the position of India as acolonial dependency, subjected to the primacy of Britishinterests, set the limits of the projects.
Key words:History of technology, industrial heritagestudies, industrial archaeology, technology transfer,diffusion, technological systems, landscapes of technology,iron and steel, charcoal iron, direct and indirect ironmaking,bloomeries, 19th century, industrial history,industrialisation, de-industrialisation, underdevelopment,colonialism, India, Sweden, Great Britain, global history,annales.
38
Af, Geijerstam Jan. "Landscapes of Technology Transfer : Swedish Ironmakers in India 1860–1864." Doctoral thesis, KTH, Industriell ekonomi och organisation, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3784.
Анотація:
In the early 1860s three Swedes, Nils Wilhelm Mitander,Julius Ramsay and Gustaf Wittenström, were engaged by theBritish to build and run charcoal-based ironworks in India.These works, the Burwai Iron Works of the British Government inthe case of Mitander and the privately owned Kumaon Iron Worksin the case of Ramsay and Wittenström, were both to bebased on the most modern European technology. The projects werepioneering in Indian ironmaking. The ambitions were high andstakes big, but after only a few years the projects were closedand the Swedes returned home.Landscapes of Technology Transferpresents a detailedstudy of the Kumaon and Burwai Iron Works, from their firstconception to their final closure. The investigation isbasically empirical and a fundamental question is: Why were theworks never brought into full and continuous production? The ironworks projects should be considered as processes oftechnology transfer rather than fully fledged and completedtransfers. In spite of this lack of success, or maybe becauseof it, the history of the ironworks and the Swedes also forms afruitful case to put other questions of wide relevance. Itexposes workings and effects of colonialism and offers anexplanation of the late development of India's iron and steelindustry and analyses of the complex totality forming theprerequisites for a successful transfer of technology. The longtraditions of bloomery ironmaking in India and ismarginalisation is also discussed. Landscapes of Technology Transferis a comprehensiveempirical study. From a local and individual perspective ittraces lines of connection across boundaries of time andgeography. The historical landscapes of technology transfer aredescribed in their cultural, social, economic and politicaldimensions and the thesis underlines the importance of a closeacquaintance with local settings and conditions, where historyis manifested in a physical presence. The remains of theironworks and theirlocal landscapes in present-day India areused as a central source for writing their histories. There isalso a strong emphasis on the use of photographs and drawingsas sources. The outcome of the projects was the result of the interplaybetween the local and the global, between a diversity ofconcrete factors influencing the construction of the works andtheir running and their colonial character. The studyemphasises the importance of technological systems andnetworks, both on a micro and a macro level. On a local leveldemanding logistics, a sometimes adverse climate, theprocurement of charcoal and iron ore in sufficient quantitiesand the build up of knowledge of ironmaking posed serious butnot insurmountable difficulties. Most obstacles were overcomealready during the first few years of the 1860s, the period ofthe Swedes, but to put the works into full and continuousproduction would have needed perseverance and purposefulefforts to support and protect the iron production, at leastduring an initial period. In the end the position of India as acolonial dependency, subjected to the primacy of Britishinterests, set the limits of the projects. Key words:History of technology, industrial heritagestudies, industrial archaeology, technology transfer,diffusion, technological systems, landscapes of technology,iron and steel, charcoal iron, direct and indirect ironmaking,bloomeries, 19th century, industrial history,industrialisation, de-industrialisation, underdevelopment,colonialism, India, Sweden, Great Britain, global history,annales.Qc 20170119
39
Günther, Katrin, Andreas Bregulla, Martin Bönsch, Frank Cichos, and Michael Mertig. "Suppressing rotational diffusion of Janus particles by surface modifications for directed thermophoretic motion." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183685.
40
Lansky, Zdenek, Marcus Braun, Wolde Pieter Rein ten, Marcel E. Janson, and Stefan Diez. "Diffusible crosslinkers generate directed forces in microtubule networks." Diffusion fundamentals 20 (2013) 34, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13601.
41
Baumgartner, Manuel [Verfasser]. "Direkte Interaktion von Hydrometeoren durch Diffusion in Mischphasenwolken / Manuel Baumgartner." Mainz : Universitätsbibliothek Mainz, 2016. http://d-nb.info/1118869338/34.
42
Delhaye, Benoït. "Etude des flammes de diffusion turbulentes : simulations directes et modélisation." Châtenay-Malabry, Ecole centrale de Paris, 1994. http://www.theses.fr/1994ECAP0396.
Анотація:
La simulation numérique directe est utilisée dans cette thèse pour étudier les flammes de diffusion turbulentes. Les simulations ont été réalisées dans deux configurations distinctes, une couche de mélange et un écoulement turbulent homogène et isotrope. L'objectif général de ce travail est l'étude détaillée des notions introduites par les modèles de flammelettes et en particulier par le modèle de flamme cohérente. Les résultats obtenus sur les taux de réaction le long du front de flamme et sur la densité de surface de flamme montrent qu'une modélisation fondée sur le concept de flamme cohérente est satisfaisante
43
Несен, Л. М., Ю. І. Богачук, В. Г. Борисенко, Л. Н. Несен, Ю. И. Богачук, В. Г. Борисенко, L. M. Nesen, Y. I. Bogachuk та V. G. Borysenko. "Активізація дифузії технологічних інновацій через залучення іноземних інвестицій в регіон". Thesis, ВНТУ, 2009. http://ir.lib.vntu.edu.ua/handle/123456789/8292.
Анотація:
Прямі іноземні інвестиції здійснюють гетерогенний вплив на регіональну та національну економіку. Це вимагає особливої аналітичної і організаційної роботи представників місцевої та регіональної влади. Прямі іноземні інвестиції супроводжуються трансфером технологій і є актом формалізованої дифузії інновацій в міжнародному масштабі. Відкритим залишається питання: чи породжують вони епіцентри дифузії інновацій? В роботі наведені соціально-економічні ефекти від здійснення прямих іноземних інвестицій, перешкоди інвестуванню в Україну, види підтримки позитивного рішення інвестором.Прямые иностранные инвестиции осуществляют гетерогенное влияние на региональную и национальную экономику. Это требует особой аналитической и организационной работы представителей местной и региональной власти. Прямые иностранные инвестиции сопровождаются трансфером технологий и являются актом формализованной диффузии инноваций в международном масштабе. Открытым остается вопрос: порождают ли они эпицентры диффузии инноваций? В работе приведены социально-экономические эффекты от осуществления прямых иностранных инвестиций, препятствия инвестированию в Украину, виды поддержки положительного решения инвестором.
Direct foreign investment carry out a heterogeneous influence on the regional and national economy. This requires special analytical and organizational work of the local and regional authorities. Foreign direct investment is accompanied by technology transfer and diffusion is an act of formal innovation internationally. The open question remains: whether they generate epicenters diffusion of innovation? The paper describes the socio-economic effects of the implementation of foreign direct investment, barriers to investment in Ukraine, the types of decision support positive investor.
44
Schmid, Fabian [Verfasser], and Klaus [Akademischer Betreuer] Spindler. "Entwicklung einer direkt solarthermisch angetriebenen Diffusions-Absorptionskältemaschine / Fabian Schmid. Betreuer: Klaus Spindler." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1090879776/34.
45
Casey, Kenan L. "Scalable, self-healing , and real-time network services for directed diffusion." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Theses/CASEY_KENAN_49.pdf.
46
Casey, Kenan L. Lim Alvin S. "Scalable, self-healing, and real-time network services for directed diffusion." Auburn, Ala., 2008. http://hdl.handle.net/10415/1165.
47
Tapachès, Émeric. "Estimation du potentiel de la technologie solaire thermodynamique à concentration en climat non désertique - Application à La Réunion." Thesis, La Réunion, 2015. http://www.theses.fr/2015LARE0011/document.
Анотація:
Le travail de recherche présenté s'inscrit pleinement dans les préoccupations énergétiques de la Réunion, en proposant d'évaluer le potentiel de la technologie solaire thermodynamique avec ou sans système à concentration en zone tropicale et les réseaux électriques non interconnectés. Le solaire thermodynamique désigne la production d'électricité à partir du rayonnement solaire via un cycle thermodynamique. En soumettant le cycle thermodynamique à une source « froide » (eau ou air ambiant) et une source « chaude » générée par des capteurs solaires l'on obtient un travail mécanique en sortie de turbine. En couplant la turbine à un alternateur de l'électricité est produite. Utilisation de capteurs à faible ou sans concentration permettent de diminuer le seuil de rentabilité des installations solaires thermodynamiques. Dans ce cas, ce type de technologie n'est plus réservé aux climats désertiques ou méditerranéens. Une étude préliminaire montre qu'elles sont exploitables en zone tropical. De plus, le couplage de l'installation à des systèmes de stockage thermique ou à des installations d'appoint utilisant de la biomasse par exemple permet de produire une énergie électrique de façon continue. Ce projet de recherche à pour but de définir les technologies adéquates, étudier finement les microclimats locaux propices à ces technologies et de réaliser un modèle numérique pour l'étude des conditions d'opération des installations solaires thermodynamiques. Ce projet permettra d'explorer une filière énergétique d'avenir et développer une expertise locale qui contribuera au rayonnement de la Réunion dans la zone océan IndienThis thesis focuses on the study of the direct solar resource received in Reunion and numerical modeling of a solar power plant consists of: 1 / a field of linear Fresnel collectors in which circulates synthetic oil; 2 / two sensible heat storage tanks; 3 / an organic Rankine cycle. The main goal is to evaluate the performance of such power plant in the island area identified as suitable.To meet this goal, several studies have been conducted: (i) a beam solar radiation map of Reunion was made from satellite images of MeteoSat 7. This map was used to assess the availability of this resource; (ii) a new global-to-diffuse irradiance decomposition model was made from based-ground measurements at Saint-Pierre. This model is based on the representation of higher probabilities of occurrence of the diffuse fraction; (iii) the geometry of the solar collector and beam solar irradiance were modeled from an existing ray-tracing code. This code has been used, firstly, to dimension the collector using an optimization method. And secondly, to develop a fast method in order to simulate absorbed flux distribution on the linear receiver elements; (iv) unsteady-state heat transfers within the solar collector was modeled with a nodal approach; (v) annual electricity production of the power plant running in the south of the island was simulated with a monitoring and control strategy relevant for the demand of the local electricity grid.The models that have been developed during this thesis are design support tools and allow the study of control strategies control of solar power plants with linear Fresnel collector
48
Karyotakis, Yannis. "Étude des photons directs produits lors des interactions hadroniques." Paris 11, 1985. http://www.theses.fr/1985PA112072.
Анотація:
Cette thèse est consacrée à l’étude des photons directs produits lors de l’interaction d’un faisceau de pions π⁺, π⁻, et protons de 200 GeV/c, avec une cible de Carbone. QCD prévoit que de tels photons sont produits par l’annihilation q q̄ → gγ ou la diffusion Compton qg → qγ. L’expérience a utilisé le spectromètre NA3 et a eu lieu au CERN. Le photon est converti dans 10% de longueur de conversion et la paire e⁺e⁻, est détectée par le système de déclenchement, qui demande une impulsion transverse supérieure à 2. 5 GeV/c. L’impulsion des électrons est mesurée par le spectromètre avec une précision de Δp/p² = 2. 10⁻⁴, alors que l’énergie et la position des photons sont mesurées par le système calorimètre – chambre à localisation des gerbes. La précision obtenue est σ(E)/E = 0. 22/√E + 0. 004 e σ(x,y) < 3 mm. Le signal des photons directs est obtenu statistiquement, après avoir corrigé le lot des candidats « photons isolés », de la contribution des π⁰η⁰. Cette correction se fait uniquement au moyen d’un programme de simulation sophistiqué, dont la partie la plus délicate est la simulation des gerbes électromagnétiques dans le calorimètre et la chambre à localisation des gerbes. Ainsi on a mis en évidence un signal de photons directs et mesuré la section efficace de ce processus. Le rapport γ/π⁰ à pt = 4. 5 GeV/c est environ 10% et semble croître avec l’impulsion transverse. La mesure de la fonction de structure du gluon dans le proton n’est pas très précise à cause des erreurs systématiques, qui sont importantesThis thesis studies direct photons produced by π⁺, π⁻ and proton beams of 200 GeV/c, momentum interacting with a Carbon target. QCD predicts that direct photons are produced either by the quark- antiquark annihilation q q̄ → gγ, or by gluon scattering qg → qγ. The experiment was performed at CERN and used the NA3 spectrometer. Photons are converted within 10% conversion length, and resulting e⁺e⁻ are detected by the trigger system which requires a minimum transverse momentum of 2. 5 GeV/c. Electrons tracks are detected by the spectrometer, and their momentum is measured with a precision of Δp/p² = 2. 10⁻⁴, while energy and position of photons are measured by an electromagnetic calorimeter and a shower chamber. Resolution on energy and positions is σ(E)/E = 0. 22/√E + 0. 004 e σ(x,y) < 3 mm. Direct photon’s signal is obtained only statistically, after correcting the “single photons” candidates for the π⁰ and η⁰ contribution. This correction is obtained only from a sophisticated Monte Carlo, in which electromagnetic shower simulation is difficult. We have observed a significant direct photon signal and we measured the cross section. The γ/π⁰ ratio at pt = 4. 5 GeV/c is about 10% and seems to grow as a function of transverse momentum. Systematic errors, which are important, limit the precision on the gluon’s structure function measurement
49
Günther, Katrin, Andreas Bregulla, Martin Bönsch, Frank Cichos, and Michael Mertig. "Suppressing rotational diffusion of Janus particles by surface modifications for directed thermophoretic motion." Diffusion funadmentals 20 (2013) 80, S. 1-2, 2013. https://ul.qucosa.de/id/qucosa%3A13666.
50
BALL, JACQUES. "Transmission, diffusion elastique et reconstruction directe des amplitudes n-p entre 0. 8 et 1. 1 gev." Paris 11, 1992. http://www.theses.fr/1992PA112187.
Анотація:
Le but du programme nucleon-nucleon a saturne ii etait de determiner des ensembles complets d'observables dans la diffusion np elastique et quasi elastique, pour acceder a la reconstruction directe des amplitudes. Les ensembles complets d'observables ont ete mesures dans un grand domaine angulaire pour des energies de 0. 84, 0. 88, 0. 940, 1. 00, et 1. 10 gev. En plus des parametres de diffusion elastique, la these contient des mesures de transmission qui determinent les differences de sections efficaces totales. Ces donnees determinent les parties imaginaires pour les amplitudes de diffusion vers l'avant et permettent de deduire les amplitudes de diffusion pour l'isospin zero. Le formalisme de la diffusion elastique du systeme nn est decrit. Le faisceau, la cible et la mesure de leur polarisation sont discutes. L'appareillage pour les differentes mesures est presente. Les resultats obtenus sont traites en detail et compares avec les donnees d'autres laboratoires. Les donnees des correlations des polarisations, des observables avec trois indices du spin, et des differences de sections efficaces polarisees avec des neutrons libres ont ete mesurees, pour la premiere fois, a saturne ii lors de cette experience