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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Conception robuste de circuits numériques à technologie nanométrique / Robust design of deep-submicron digital circuits

Gonçalves Dos Santos Junior, Gutemberg 06 September 2012 (has links)
Avec l'augmentation de la probabilité de fautes dans les circuits numériques, les systèmes développés pour les environnements critiques comme les centrales nucléaires, les avions et les applications spatiales doivent être certifies selon des normes industrielles. Cette thèse est un résultat d'une cooperation CIFRE entre l'entreprise Électricité de France (EDF) R&D et Télécom Paristech. EDF est l'un des plus gros producteurs d'énergie au monde et possède de nombreuses centrales nucléaires. Les systèmes de contrôle-commande utilisé dans les centrales sont basés sur des dispositifs électroniques, qui doivent être certifiés selon des normes industrielles comme la CEI 62566, la CEI 60987 et la CEI 61513 à cause de la criticité de l'environnement nucléaire. En particulier, l'utilisation des dispositifs programmables comme les FPGAs peut être considérée comme un défi du fait que la fonctionnalité du dispositif est définie par le concepteur seulement après sa conception physique. Le travail présenté dans ce mémoire porte sur la conception de nouvelles méthodes d'analyse de la fiabilité aussi bien que des méthodes d'amélioration de la fiabilité d'un circuit numérique. / The design of circuits to operate at critical environments, such as those used in control-command systems at nuclear power plants, is becoming a great challenge with the technology scaling. These circuits have to pass through a number of tests and analysis procedures in order to be qualified to operate. In case of nuclear power plants, safety is considered as a very high priority constraint, and circuits designed to operate under such critical environment must be in accordance with several technical standards such as the IEC 62566, the IEC 60987, and the IEC 61513. In such standards, reliability is treated as a main consideration, and methods to analyze and improve the circuit reliability are highly required. The present dissertation introduces some methods to analyze and to improve the reliability of circuits in order to facilitate their qualification according to the aforementioned technical standards. Concerning reliability analysis, we first present a fault-injection based tool used to assess the reliability of digital circuits. Next, we introduce a method to evaluate the reliability of circuits taking into account the ability of a given application to tolerate errors. Concerning reliability improvement techniques, first two different strategies to selectively harden a circuit are proposed. Finally, a method to automatically partition a TMR design based on a given reliability requirement is introduced.

The implementation of a fault-tolerant computer system for space instrumentation

Jing, Ming-Haw January 1992 (has links)
No description available.

Film deposition and microfabrication of magnetic tunnel junctions with an MgO barrier

Du, Yuqing January 2012 (has links)
Magnetic tunnel junctions (MTJs), which consist of a thin insulation layer sandwiched by two ferromagnetic (FM) layers, are among the key devices of spintronics that have promising technological applications for computer hard disk drives, magnetic random access memory (MRAM) and other future spintronic devices. The work presented here is related to the development of relevant techniques for the preparation and characterization of magnetic films, exchanged biased systems and MTJs. The fabrication and characterization of PtMn/CoFe exchange biased systems and MTJs with Al-O barriers were undertaken when the new Aviza StratIon fxP ion beam deposition tool was developed by the project consortium funded by DTI MNT. After the Nordiko 9550 spintronic deposition tool was installed at Plymouth, the work focused on the development of MTJ multilayer stacks with layer structures of CoFeB/MgO/CoFe/IrMn and IrMn/CoFeB/MgO/CoFeB to achieve coherent tunneling with a crystalline MgO barrier. The film deposition, microfabrication, magnetic field annealing, microstructural and nano-scale characterization, magnetic and magneto-transport measurement for these devices have been systematically studied to achieve smooth interfaces and desired crystallographic textures and magnetic properties of layer stacks. Magnetoresistance (MR) of up to 200% was obtained from MTJs with a layer structure of Ta/CuN/Ta/CoFeB/MgO/CoFe/IrMn/Ta and a CuN bottom electrode. Enhanced exchange anisotropy from the bottom pinned IrMn/CoFeB stacks has been obtained, which demonstrated the possibility of fabricating MTJs with CoFeB as both the top and bottom FM electrodes with strong exchange bias. The origin of the enhanced exchange bias field was studied by employing high resolution transmission electron microscopy (HRTEM) and x-ray magnetic circular dichroism (XMCD) to examine the mmicrostructure properties and element specific magnetic properties of the stacks. Results demonstrate that the enhanced exchange anisotropy in the IrMn/CoFeB system is closely associated with the increased uncompensated interfacial spins. MTJs with layered structures of IrMn/CoFeB/MgO/CoFeB were prepared based on this exchange bias system. However, further work is required for the optimisation of the (001) crystallographic textures of the CoFeB/MgO/CoFeB stack to achieve coherent tunneling.

Vliv zkrmování přípravku TMR Balance na užitkovost dojnic ve vybraném chovu / Influence of feeding TMR Balance on milk yield of dairy cows in a selected breed

Pitrmucová, Dagmar January 2016 (has links)
In this thesis, it was analysed the current nutrition of cattle especially in calves and cos, because nutrition plays a signifiant role in these categories, leading to the following high milk production. The content of the work is mainly focused on the nutrition of dairy cows and their performance when feeding different feed rations, which were presented to the time in the years 2013/2014 and 2015. Ration differed only in the administered of the product B, when TMR Balance from the time this was shot administered from May 2014. The observation took place on private agricultural farm in Podkrkonoší. The farm was observed a group of dairy cows, mostly Czech pied breed, which had a combined 34 pieces, 4 Holsteins and 30 Czech pied breed. The group of animals arrived in the feed ration years 2013/2014 without granulate TMR Balance B and the same group of dairy cows, then began to submit feed ration with granulate. Statistically are evaluated on the first lactation cows, which were given the first shot immediately after calving. A group of cows which was observed on the first lactation include 11 cows. The work was observed their performance according to the above data form performance tests conducted by the Bohemian- Moravian Association of breeders. On the basis of the results achieved can be stated, that the preparation of TMR Balance B added to the diet increased the productivity of dairy cows on the farm, because the settlement has occurred, the ration supply a sufficient amount of vitamins and minerals needed to produce more high - quality milk and better health of dairy cows. Milk yield of milk is according to achieved and evidence of the results of picking up on the 614,64 kg in 305 days of lactation, on the 802,91 kg in 200 days of lactation, on the 371,59 kg in 100 days of lactation. Demonstrated also increased the performance of the protein for the 28,93 kg.

Vliv technologických postupů na kvalitu siláží v měnících se ekonomických podmínkách

Neuman, Aleš January 2017 (has links)
This research describes several major crops grown in the Czech Republic for ensiling and production of bulk feed for dairy cows. It describes their growing technology, harvesting technology and the ensilage process. It also evaluates the impact of the weather, especially its extreme fluctuations in recent times on the quality of the forage and the resulting canned fodder. It evaluates the quality of the feeds of a particular company on the basis of the analysis of silage from different years. Based on an analysis of the company's accounting records, the valuation of bulk feeds produced by the company itself. Subsequently, she is evaluating feed rations of individual groups of dairy cows for the reference period of 15 months. It evaluates the efficiency of feed rations, hence the profitability of the whole breed and the possibility of responding to fluctuations in prices on the agrarian market.

Radiation Hardened System Design with Mitigation and Detection in FPGA

Sandberg, Hampus January 2016 (has links)
FPGAs are attractive devices as they enable the designer to make changes to the system during its lifetime. This is important in the early stages of development when all the details of the final system might not be known yet. In a research environment like at CERN there are many FPGAs used for this very reason and also because they enable high speed communication and processing. The biggest problem at CERN is that the systems might have to operate in a radioactive envi- ronment which is very harsh on electronics. ASICs can be designed to withstand high levels of radiation and are used in many places but they are expensive in terms of cost and time and they are not very flexible. There is therefore a need to understand if it is possible to use FPGAs in these places or what needs to be done to make it possible. Mitigation techniques can be used to avoid that a fault caused by radiation is disrupting the system. How this can be done and the importance of under- standing the underlying architecture of the FPGA is discussed in this thesis. A simulation tool used for injecting faults into the design is proposed in order to verify that the techniques used are working as expected which might not always be the case. The methods used during simulation which provided the best protec- tion against faults is added to a system design which is implemented on a flash based FPGA mounted on a board. This board was installed in the CERN Proton Synchrotron for 99 days during which the system was continuously monitored. During this time 11 faults were detected and the system was still functional at the end of the test. The result from the simulation and hardware test shows that with reasonable effort it is possible to use commercially available FPGAs in a radioactive environment.

Transmyocardial Laser Revascularization and Stem Cell Therapy to Remodel an Infarcted Heart

Iwanski, Jessika, Iwanski, Jessika January 2016 (has links)
Transmyocardial revascularization (TMR) has emerged as an additional therapeutic option for patients suffering from diffuse coronary artery disease (CAD), providing immediate angina relief. The current potential of this therapy focuses on the injection of stem cells, in order to create a synergistic angiogenic effect while increasing myocardial repair and regeneration. Although TMR procedures provide increased vascularization within the myocardium, patients suffering from ischemic cardiomyopathy may not benefit from angiogenesis alone. Therefore, the goal of introducing stem cells is to restore the functional state of a failing heart by providing stem cells with a favorable microenvironment that will enhance their engraftment. Since the therapeutic effect of stem cells is dependent on their capacity to survive and retain in the myocardium, laser therapy may provide a strategy for increasing stem cell engraftment. If so, these cells may have the potential to act as mitochondrial donors or as sources of paracrine factors, aiding in the recovery from oxidative stress and providing antioxidant reserves. Furthermore, laser therapy may also play an influential role in regulating cardiac repair and regeneration via epithelial-mesenchymal transition (EMT). By interacting with specific transcription factors TMR may provide another pathway by which it can offer reparative effects. Cumulatively, paracrine release, denervation, and angiogenesis contribute to the therapeutic benefits experienced by TMR patients, including a significant reduction in angina, with increases in myocardial perfusion and survival rates. With the addition of stem cells, these effects may be further augmented, thus providing increased symptomatic relief in patients.

Stanovení in vitro stravitelnosti sušiny a organické hmoty směsných krmných dávek s rozdílným zastoupením krmných surovin

Vojkovská, Jitka January 2017 (has links)
Review of this thesis concisely describes total mixed ration (TMR) aproach, introduces INRA and CNCPS systems of evaluating rations for dairy cattle according nutritional requirements. Also there are described requirements of feed quality, structure and interaction between nutrients and organic matter digestibility. The experiment evaluates in vitro digestibility of dry matter and organic matter of different rations. Specifically rations for cow in early lactation, in the peak of lactation and for dry cows. The digestibility is compared according to nutrient composition. The digestibility was evaluated on Daisy Incubator (ANKOM TECHNOLOGY). For evaluating of results were used MS Excel and STATISTICA softwares. For statistical evaluatig were used regression analysis and Kruskal Wallis test.

Einfluß der magnetischen Dipolkopplung auf den Tunnelmagnetowiderstand in Schichtsystemen und strukturierten Elementen

Tegen, Stefan 12 January 2002 (has links) (PDF)
We have studied the effect of the dipolar magnetic coupling (also known as Néel coupling or "orange-peel" coupling) in tunneling magnetoresistive (TMR) elements. With an in situ scanning tunneling microscope we directly accessed the roughness of the films and found a close correspondence between the values for the coupling fields determined by the magneto-optical Kerr effect and the ones computed on the basis of the measured morphology parameters. We confirm an increase of the dipole coupling between magnetic layers with decreasing barrier thickness as predicted by the model. Deviations from the theoretical predictions are observed for the case of thinner soft magnetic layers, which can be explained by reduced magnetisation in very thin films. We demonstrate the importance of dipolar coupling for understanding the magnetic behaviour of TMR elements by comparing TMR curves for optimised and nonoptimised structures.

Impact of structural defects on spin-polarized transport across magnetic tunnel junctions / L'effet des défauts structuraux sur le transport polarisé en spin dans les jonctions tunnel magnétiques

Schleicher, Filip 10 December 2012 (has links)
Dans le manuscrit, nous étudions l’impact des défauts sur le transport électronique dépendant du spin dans les jonctions tunnel magnétiques (JTM). Ces études ont été effectuées sur des hétérostructures possédant des barrières tunnel composé de SrTiO3, TiO2 et de MgO. Dans le cas des deux premières structures, nous montrons comment l’oxydation à l’interface induit réduction très prononcée de la magnétorésistance tunnel (TMR). Dans le cas du MgO, des études optiques sur les états induits par les défauts dans la barrière isolante ont été effectué. Nous avons montré qu’il est possible de contrôler la densité de certain type de défaut (lacune d’oxygène) en altérant les conditions de dépôts du MgO. Les études électriques et optiques effectué sur ces échantillons permettent de remonter à l’énergie des défauts au sein de la barrière. Les méthodes d’analyses des mesures électrique Î (I chapeau), qui représente la variation relative ou absolue du courant électrique en fonction de la température, permet de définir différents régime de transport à travers les jonctions CoFeB/MgO/CoFeB. Le régime intrinsèque observé à basse température s’explique par les effets de structure de bande du CoFeB et du MgO (filtrages des électrons de différente symétrie par la barrière de MgO), tandis que le régime « extrinsèque » observé aux températures intermédiaires résulte d’une activation thermique progressive des lacunes d’oxygène et est accompagné d’une réduction de la résistance ainsi que du signal TMR. Nous avons également montré dans des études préliminaires qu’une excitation optique des défauts a un impact sut le magnéto-transport. / In the manuscript it is presented how the spin-polarized transport across magnetic tunnel junctions (MTJ) is affected by presence of structural defects within the barrier and at its interfaces. Studies concern structures incorporating SrTiO3, TiO2 and MgO insulators. In case of the first two structures it is shown how interfacial oxidation results in the drastically reduced value of the tunnelmagnetoresistance (TMR). In case of the MgO barrier, extensive studies on defect sites within the crystalline network of the insulator are performed. It is shown that one may control density of certain types of oxygen vacancies by altering growth conditions of the MgO layer. Further electrical and optical studies give insight into energetical positioning of these defect sites. Extension of the Î magnetotransport analysis method from the ‘absolute’ to the ‘relative’ case reveals several regimes of transport across CoFeB/MgO/CoFeB junctions. The low-temperature ‘intrinsic’ regime is attributed exclusively to the band structure effects of the CoFeB electrodes, whereas the mid- to room-temperature ‘extrinsic’ regimes result from the gradual incidence of thermally activated defect sites on the spin-polarized transport, which is accompanied by an increased reduction of both the resistance and the TMR signal. Initial experiments show that optical excitation of the defect sites has a crucial impact on the magnetotransport.

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