Дисертації з теми "Variation de charge active"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Variation de charge active.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Variation de charge active".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Capelli, Thomas. "Amplificateur de puissance pour réseaux phasés d’antenne 5G multi-bande en technologie ST CMOS065SOIMMW." Thesis, Bordeaux, 2022. http://www.theses.fr/2022BORD0176.
Анотація:
Les télécommunications mobiles, afin de subvenir à leurs insatiables besoins, trouvent des moyens d’améliorer leurs capacités depuis maintenant plus de trente ans. En 2019 la cinquième génération (5G) est à l’épreuve afin de garantir une connexion non seulement au marché des téléphones mobiles toujours croissant, mais aussi au vaste univers de l’internet des objets (IoT). Afin de pouvoir remplir ses objectifs, la 5G marque une expansion sans précédent en matière de bandes de fréquences utilisées. En effet, des bandes jusqu’à 60 GHz et plus font partie des ambitions du réseau et cela implique de radicaux changements technologiques qui impactent toute l’électronique dédiée. Nouvelles fréquences plus élevées, pertes de propagation dans l’air plus élevées et niveau d’exigences relevé, les réseaux phasés d’antenne sont introduits pour pallier à toutes ces contraintes et imposent une toute nouvelle architecture système et une interface inédite pour les front-end RF des communications mobiles.Dans ce travail, nous proposons donc une analyse de ces réseaux d’antennes phasés et des contraintes qu’ils représentent en particulier pour les amplificateurs de puissance (PA), tel que la variation de charge parasite et le comportement des composantes générées par le comportement non-linéraire de ces derniers. Une évaluation de la variation de charge active due aux différents couplages existants dans les réseaux d’antennes est proposée ainsi que de son impact sur la performance des amplificateurs notamment en termes d’efficacité (PAE). Le comportement des non-linéarités telles que les produits d’intermodulation du troisième ordre (IMD3) est montré dans les réseaux d’antennes. Un concept utilisant le principe de génération et d’orientation de faisceau des réseaux d’antennes est proposé, permettant de relâcher les contraintes de linéarité des amplificateurs 5G et ainsi de permettre une réduction de leur consommation d’énergie. Une implémentation d’un PA utilisant ce principe est démontrée en technologie ST CMOS 65 nm PD-SOI à 28 GHzMobile telecommunications, in order to support its insatiable needs, has been finding ways to improve its capabilities for over thirty years now. In 2019 the fifth generation (5G) is on trial to ensure connection not only to the ever-growing cell phone market, but also to the vast world of the Internet of Things (IoT). In order to meet its goals, 5G marks an unprecedented expansion in the frequency bands used. Indeed, bands up to 60 GHz and beyond are part of the network's ambitions and this implies radical technological changes that impact all dedicated electronics. New higher frequencies, higher propagation losses in the air, and higher requirements, antenna phased arrays are introduced to overcome all these constraints and impose a completely new system architecture and interface for the RF front-end of mobile communications.In this work, we propose an analysis of these phased antenna arrays and the constraints they represent particularly for power amplifiers (PA), such as the parasitic load variation and the behavior of the components generated by the non-linear behavior of the latter. An evaluation of the active load variation due to the different coupling existing in the antenna networks is proposed as well as its impact on the performance of the amplifiers, particularly in terms of power added efficiency (PAE). The behavior of nonlinearities such as third-order intermodulation products (IMD3) is shown in antenna arrays. A concept using the principle of beam generation and steering of antenna arrays is proposed, allowing for relaxing the linearity constraints of 5G amplifiers and thus allowing a reduction of their power consumption. An implementation of an AP using this principle is demonstrated in ST CMOS 65 nm PD-SOI technology at 28 GHz
2
Leclerc, Julien. "Utilisation innovatrice de l'aluminium dans les ponts : effets de la variation de la température sur le comportement structural d'un tablier à platelage d'aluminium sur poutres d'acier, à action composite." Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/30272.
Анотація:
Le présent document traite de l'utilisation d'un nouveau platelage en aluminium, présentement développé à l'Université Laval. Ce nouveau platelage, d'une hauteur de 200 mm, se veut une alternative aux dalles en béton armé couramment utilisées dans les ponts routiers. Il est proposé de connecter le platelage à des poutres en acier à l'aide d'une connexion boulonnée antiglissement utilisant des boulons en acier galvanisé ASTM F3125/F3125M-15a de grade A325 et de diamètre M20. L'optique est de développer une action composite totale afin d'obtenir la pleine capacité de la poutre mixte. Cependant, le coefficient de dilatation thermique de l'aluminium étant le double de celui de l'acier, des mouvements différentiels entre le platelage en aluminium et les poutres en acier sont possibles suite à des variations de température. Le comportement de cet assemblage sous les charges thermiques doit donc être étudié. Ce projet propose d'utiliser la méthode des éléments finis à l'aide du logiciel commercial Abaqus afin de déterminer le comportement de cet assemblage face à la combinaison des charges thermiques et mécaniques à l'état limite d'utilisation (ÉLUT) ainsi qu'à l'état limite ultime (ÉLUL). Ces charges sont déterminées à partir des directives du Code canadien sur le calcul des ponts routiers (CAN/CSA S6-14). Les résultats montrent qu'il est possible de développer l'action composite totale entre le platelage en aluminium et les poutres en acier. Aussi, en suivant les recommandations prescrites par cette étude, il est possible de prévenir le glissement sous les charges thermiques et de maintenir le comportement antiglissement de l'assemblage à l'ÉLUT en plus de prévenir la rupture de l’assemblage boulonné sous la combinaison des charges thermiques et mécaniques à l’ÉLUL.This project concerns the use of a new aluminium bridge deck that is being developed at Université Laval. It is a 200 mm deep aluminium bridge deck, which represents an alternative to the reinforced concrete slabs in bridges. This project proposes to connect the aluminium bridge deck to steel girders using galvanized ASTM F3125/F3125M-15a grade A325 bolts of diameter M20 in a slip-critical connection. Full composite action between the deck and the girders is expected in order to develop the full capacity of the composite section. However, the coefficient of thermal expansion of aluminium, being twice that of steel, differential movements may occur during temperature changes. To understand the behavior of the bolted connection under such thermal loadings, this project uses finite element model with the Abaqus software. The combinations of dead, live and thermal loads at the ultimate limit state (ULS) and serviceability limit state (SLS) are studied. The loads are calculated according to the Canadian Highway Bridge Design Code (CAN/CSA S6-14). Results confirm that full composite action between the aluminium deck and the steel girders can be achieved. Moreover, by following the recommendations of this study, it is possible to eliminate the sliding that may occur during the thermal loading of the beam at the serviceability limit state (SLS). This study also offers a solution to prevent the failure of the bolted connections following the combination of thermal and mechanical loads.
3
Chuang, Ying-Chieh. "Floating capacitor active charge balancing for PHEV applications." Connect to resource, 2010. http://hdl.handle.net/1811/45430.
4
Vaughan, Joshua Eric. "Use of Active and Semi-Active Control to Counter Vehicle Payload Variation." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5251.
Анотація:
All vehicles have changing payloads that affect their dynamic response. Compared to passenger vehicles, heavy machinery have larger and more greatly varying payload masses, higher centers of mass, and encounter larger disturbances. These factors lead to significant increases in the amount of vibration experienced by heavy machinery operators. This fact, when coupled with the large amount of exposure time that a typical heavy machinery operator incurs, leads to much greater vibration dosage values for the heavy machinery operator. In addition, the heavy machinery operator faces equal or greater opportunity for accident. The chance of accident, along with the increased vibration dosage, leads to an operating condition with significant safety risks, both short and long term.
It has been shown that payloads affect both the stability and vibration isolation properties of a vehicle. Large payloads reduce vehicle stability while increasing the amount of vibration transmitted to the operator. A method to compensate for these loading affects would prove to be a useful technique to increase the safety of the vehicle, both in terms of accident avoidance and long term health effects of vibration.
This thesis provides such payload compensation techniques. Improved vehicle dynamics were accomplished with the use of both active and semi-active suspension control. The active systems used are optimal control based, and provided the greatest improvements in vehicle performance. An optimal controller designed around a nominal payload, however, proved insufficient for operation over the entire payload range due to too large peak actuator forces at low payloads. A multiple model approach was used to remedy this problem.
Semi-active systems based on a Linear Quadratic Regulator with output feedback and damping selection via static deflection were developed. The semi-active systems would require far less power than the active systems, with the need for knowledge of fewer systems states. It was shown that despite these lower demands, the semi-active systems closely approach the performance of the fully active systems.
5
Schoenenberger, Sandrine. "Variation de prise en charge des patients : discrimination dans les soins et/ou charge de travail élevée." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0419/document.
Анотація:
Les études françaises sur la discrimination en milieu médical s’intéressent aux refus de soins des libéraux selon le système d’assurance des patients. Les recherches anglo-saxonnes examinent les différences de prises en charge sous l’angle de l’ethnie du patient. Burgess (2010) suggère que les discriminations en milieu médical peuvent être plus fréquentes lorsque le soignant est placé sous un niveau élevé de charge cognitive. Les recherches dans le domaine de la psychologie du travail et l’ergonomie indiquent que dans les cas de surcharge de travail, l’opérateur modifie son activité. Les comportements qualifiés de discriminatoires pourraient alors être le résultat des mécanismes de régulation de la charge de travail. Deux vagues d’entretiens auprès de soignants (N = 22 pour la première étude et N = 6 pour la seconde) indiquent un lien de leur part entre discrimination et charge de travail. Les observations menées en milieu hospitalier et couplées à un questionnaire et le NASA-TLX (N = 121) ont permis de constater que les discriminations en milieu médical sont faibles. Elles concernent uniquement la dimension relationnelle, les actes médicaux (examens, soins) sont réalisés normalement. Les variations constatées dans les comportements des soignants adviennent à l’encontre de patients stigmatisés et difficiles à gérerThe French studies about discrimination in medical settings are focused on the general practitioners’ refusal to provide care depending on the patient’ insurance cover. Anglo-Saxon research examines the differences in care according to the patient’s ethnicity. Burgess (2010) suggests that discriminations in healthcare settings may happen more frequently when health care providers are put under high levels of cognitive load. Research in the fields of occupational psychology and ergonomics indicates that in cases of work overload, workers change their activity. Behavior described as discriminatory might result from regulation mechanisms of work overload regulation mechanisms. Two waves of interviews with healthcare providers (N = 22 for the first time and N = 6 for the second time) point to a link between discrimination and workload. Observations conducted in hospital settings and associated with a questionnaire as well as the NASA-TLX (N = 121) have shown that discriminations in a medical environment are limited. They are only related to the interpersonal aspect of care: medical acts (examination, care) are properly completed. The variations in the healthcare providers’ behavior occur when dealing with stigmatized patients and patients who are difficult to manage
6
Greig, Thomas Alexander. "Development of CMOS active pixel sensors." Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/5345.
Анотація:
This thesis describes an investigation into the suitability of complementary metal oxide semiconductor (CMOS) active pixel sensor (APS) devices for scientific imaging applications. CMOS APS offer a number of advantages over the established charge-coupled device (CCD) technology, primarily in the areas of low power consumption, high-speed parallel readout and random (X-Y) addressing, increased system integration and improved radiation hardness. The investigation used a range of newly designed Test Structures in conjunction with a range of custom developed test equipment to characterise device performance. Initial experimental work highlighted the significant non-linearity in the charge conversion gain (responsivity) and found the read noise to be limited by the kTC component due to resetting of the pixel capacitance. The major experimental study investigated the contribution to dark signal due to hot-carrier injection effects from the in-pixel transistors during read-out and highlighted the importance of the contribution at low signal levels. The quantum efficiency (QE) and cross-talk were also investigated and found to be limited by the pixel fill factor and shallow depletion depth of the photodiode. The work has highlighted the need to design devices to explore the effects of individual components rather than stand-alone imaging devices and indicated further developments are required for APS technology to compete with the CCD for high-end scientific imaging applications. The main areas requiring development are in achieving backside illuminated, deep depletion devices with low dark signal and low noise sampling techniques.
7
Attallah, Faouzi. "Variation des périodes radioactives en fonction de l'état de charge atomique : cas du ¹²⁵Te." Bordeaux 1, 1994. http://www.theses.fr/1995BOR1A522.
8
SIVERTI, ARNAUD. "Commande a structure variable appliquee au positionnement d'une charge mecanique a forte variation parametrique." Amiens, 2000. http://www.theses.fr/2000AMIE0113.
Анотація:
Aujourd'hui, les actionneurs electriques doivent realiser des taches de plus en plus precises tout en evoluant dans des environnements ou les variations brusques de configuration mecanique sont frequentes et consequentes (variation d'inertie, de frottement visqueux et de couple de charge). C'est alors a la partie commande que l'on confie le soin de faire face aux variations de l'environnement pour fournir des signaux qui permettront a l'actionneur de repondre aux specifications demandees. Aussi, avec l'arrivee des processeurs numeriques, de nombreuses theories telles que la commande predictive, la commande optimale ou encore la commande adaptative sont apparues dans la litterature. Appliques aux moteurs electriques, ces algorithmes presentent des proprietes remarquables d'insensibilite vis a vis de l'environnement mecanique. Cependant, ces techniques innovantes n'ont pas reussi a penetrer le monde industriel du fait de leur important volume de calcul qui necessite l'emploi de plateforme informatique du type dsp (digital signal processor). L'objectif de cette these consiste donc a appliquer la theorie de la commande a structure variable (csv) a un moteur a courant continu entrainant une charge mecanique a forte variation parametrique telle qu'on la rencontre en commande numerique de machines-outils ou en robotique. Le but final est de determiner un algorithme qui soit a la fois robuste et implantable sur une architecture informatique peu onereuse du type microcontroleur. Deux approches de csv, l'une classique (csv par commutation au niveau de l'organe de commande) et l'autre plus originale (csv par modification du retour d'etat) sont testees dans un premier temps en simulation a l'aide de profils de deplacement types. Une fois cette phase de tests terminee, ces deux techniques sont implantees sur un microcontroleur intel 80c196kb puis validees experimentalement a l'aide d'un banc d'essais a configuration mecanique variable mis au point avec le partenaire industriel.
9
Lavallée, Bernard. "Variation du taux de dépérissement de la biomasse active hétérotrophe du modèle ASM1." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ57817.pdf.
10
Pan, Fangfang [Verfasser]. "Crystal Engineering and Charge Density Studies on Pharmaceutically Active Derivatives of Sulfonamides / Fangfang Pan." Aachen : Shaker, 2013. http://d-nb.info/1050344375/34.
11
Bapela, Mahwahwatse Johanna. "Variation of active constituents in Euclea natalensis based on seedling stages, seasons, and fertilizers." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-06262008-095522/.
12
Li, Shuo. "6 GHz RF CMOS Active Inductor Band Pass Filter Design and Process Variation Detection." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1420812588.
13
Bapela, Mahwahwatse Johanna. "Variation of active constituents in Euclea natalensis based on seedling stages, seasons, and fertilizers." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/25856.
Анотація:
Euclea natalensis A.DC. belongs to the Ebenaceae family, and is extensively distributed along the eastern coast of southern Africa. Many Euclea species are widely gathered by indigenous people because of their medicinal properties. Roots of these plant species are frequently used to treat respiratory complications such as chest pains, bronchitis, pleurisy and asthma. Ground root powder is topically applied in cases of leprosy and is used by some ethnic groups to treat toothache and headache. The bioactivity encountered is attributable to naphthoquinones, which are common phenolic compounds in the Ebenaceae family. Naphthoquinones isolated from E. natalensis (shinanolone, 7-methyljuglone, diospyrin, isodiospyrin and neodiospyrin) have exhibited a broad spectrum of antimicrobial activity. The demand for these products will escalate due the amount of plant material required to further research. We need to explore techniques that can maximize their productivity. The present study was conducted on E. natalensis, in an attempt to establish if there exists any correlation between the accumulation of naphthoquinones and stages of seedling growth, seasonal fluctuations and application of fertilizers. A possible correlation between seedling growth stages and the accumulation of naphthoquinones (shinanolone, 7-methyljuglone and diospyrin) was investigated in seeds and seedlings of Euclea natalensis. In this study, the seeds represented the first stage, whereas the second seedling stage was defined as the stage when the radicles were about 6 cm long. The lengths of the seedlings at the third, fourth and fifth seedling stages were 9 cm, 12 cm and 16 cm respectively. Plant materials collected from the five seedling stages were separately extracted using chloroform and the naphthoquinones were then quantified by means of High Performance Liquid Chromatography (HPLC). Mobile phase of MeCN: H2O: AcOH (62.5: 32.5: 5) was used as an eluent in an isocratic mode and at a flow rate of 0.8 ml/min. Standard curves of each of the four compounds were obtained by making a series of dilutions in the concentration range of 22.5 µg/ml to 2.25 µg/ml. Ten microlitres of each dilution was injected three times into the HPLC, and the run time for each injection was 20 minutes. Calibration curves were then generated and used for the quantification of each compound. Shinanolone, which was the only naphthoquinone detectible in seeds, accumulated at variable rates (P<0.01) and no trend could be established between its synthesis and seedling growth. The content of shinanolone ranged from 87.5 mg/kg dry weight (dw) in seeds to a high mean value of 1047 mg/kg (dw) during the fourth seedling stage. A significant correlation (P<0.01) was found between the mean concentrations of 7-methyljuglone and seedling growth. 7-Methyljuglone was quantified at a high mean level of 5003 mg/kg during the third seedling stage and was not detected in the seed samples. A positive correlation (P<0.01) was established between the concentration of diospyrin and seedling stages. Diospyrin was detected at an elevated mean concentration of 6182 mg/kg during the fifth seedling stage, which was higher than the other quantified naphthoquinones. Seasonal variation of naphthoquinones (shinanolone, 7-methyljuglone, diospyrin, isodiospyrin and neodiospyrin) was investigated from eleven plants of E. natalensis subsp. natalensis growing in natural populations, over a period of four seasons. The roots were harvested, dried, extracted and analysed as in the previous study. The mean levels of shinanolone and 7-methyljuglone were found to be uniform in all the seasons and no statistically significant variation could be found between seasonal changes and their mean concentrations. Accumulation of isodiospyrin and neodiospyrin varied significantly with seasonal changes (P<0.05). These two bioactive naphthoquinones were detected only in summer and autumn respectively, and not in winter. A statistically significant variation (P<0.05) was established between the levels of diospyrin and seasonal fluctuations. Diospyrin was detected at a mean concentration of 3190 mg/kg (dw) during spring, which was higher than the other naphthoquinones quantified in all four seasons. The effect of NPK fertilizers on growth performance and accumulation of naphthoquinones (shinanolone, 7-methyljuglone, diospyrin, isodiospyrin and neodiospyrin) in seedlings of E. natalensis grown in shade and under field conditions was investigated. Each group was subdivided into four subgroups, which were then subjected to four respective treatments of water-soluble foliar feed (2:1:2 (44) NPK) at three different concentrations. Treatments tested were as follows: Treatment 1 at 40 g/l, Treatment 2 and Treatment 3 at 20 g/l and 10 g/l respectively. The control group received only supplemental water. The first harvest was conducted after 6 months of application of fertilizers and the second one was done after 12 months of treatment. Roots and shoots were harvested and analysed separately. The naphthoquinones were quantified as previously described. The bioactivity of root extracts from seedlings was tested against Mycobacterium smegmatis and extracts with lower MIC were further tested on M. tuberculosis. Growth parameters differed between the two groups, with seedlings from the shadehouse showing more plant vigour than the field grown plants. No significant interaction could be established between the measured growth factors and treatment. A significant interaction (P<0.001) was found between Treatment 2 and shadehouse seedlings. Treatment 2 enhanced vegetative performance with the mean values of fresh weight of shoots and roots being twice as much as their respective control mean values. A significantly positive correlation was established between the concentration of shinanolone (P<0.01), isodiospyrin (P<0.05) and neodiospyrin (P<0.05) with fertilization from field-grown seedlings. Application of NPK fertilizers significantly (P<0.05) increased the accumulation of neodiospyrin in seedlings subjected to shadehouse conditions. The most potent naphthoquinone, 7-methyljuglone, was found to be abundant in all the extracts and was quantified at a high mean concentration of 10200 mg/kg from shadehouse seedlings. Root extracts of E. natalensis seedlings grown under field conditions were generally more active against the bacterial strain of M. smegmatis as compared to extracts acquired from roots of seedlings maintained under a shadehouse setting. A lowest minimum inhibitory concentration (MIC) of 0.78mg/ml against M. smegmatis was observed from the second harvest of field-cultivated seedlings of the control and Treatment 1 subgroups. The MIC values for shadehouse seedlings ranged from 1.6 to 6.3 mg/ml. Minimum bactericidal concentration (MBC) values from all the extracts tested were relatively higher than their respective MIC’s. Root extracts of E. natalensis were more active against M. tuberculosis and their MIC values were lower than the tested concentrations. Extracts acquired from field-grown seedlings were more active against M. smegmatis with a lowest MIC value of 0.78 mg/ml. Extracts from the control group and Treatment 1, which had less application of fertilizers were more active against strains of M. tuberculosis with MIC value of 10 µg/ml. This shows the selectivity of E. natalensis against the mycobacterial strain of M. tuberculosis. Based on the findings, synthesis and accumulation of naphthoquinones in E. natalensis is highly variable within individuals of the species investigated. Naphthoquinones accumulate in relatively higher amounts in roots of E. natalensis than in the aboveground structures, which validate their harvest by indigenous people. The concentration of shinanolone varied slightly and its production increased with seedling growth. The synthesis of 7-methyljuglone is independent of fertilisation as its accumulation was enhanced in seedlings subjected to control treatment. Neodiospyrin and isodiospyrin were always present in every sample obtained from the seedlings but they were not detectible in every profile of samples from mature plants. Diospyrin is the only naphthoquinone that was detected in every sample analysed and also quantified in high concentrations from mature plants harvested in spring. The study showed that depending on the requirement of a particular naphthoquinone for research, one could target the seasons and seedling stages recommended from this study. This study also showed that field-cultivated seedlings produced more potent naphthoquinones than the ones subjected to controlled environments.Dissertation (MSc (Plant Science))--University of Pretoria, 2008.
Plant Production and Soil Science
unrestricted
14
Grigoriev, Igor. "Turbulence modeling of compressible flows with large density variation." Doctoral thesis, KTH, Turbulens, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183452.
Анотація:
In this study we highlight the influence of mean dilatation and mean density gradient on the Reynolds stress modeling of compressible, heat-releasing and supercritical turbulent flows.Firstly, the modeling of the rapid pressure-strain correlation has been extended to self-consistently account for the influence of mean dilatation.Secondly, an algebraic model for the turbulent density flux has been developed and coupled to the tensor equationfor Reynolds stress anisotropy via a 'local mean acceleration',a generalization of the buoyancy force. We applied the resulting differential Reynolds stress model (DRSM) and the corresponding explicit algebraic Reynolds stress model (EARSM) to homogeneously sheared and compressed or expanded two-dimensional mean flows. Both formulations have shown that our model preserves the realizability of the turbulence, meaning that the Reynolds stresses do not attain unphysical values, unlike earlier approaches. Comparison with rapid distortion theory (RDT) demonstrated that the DRSM captures the essentials of the transient behaviour of the diagonal anisotropies and gives good predictions of the turbulence kinetic energy. A general three-dimensional solution to the coupled EARSM has been formulated. In the case of turbulent flow in de Laval nozzle we investigated the influence of compressibility effects and demonstrated that the different calibrations lead to different turbulence regimes but with retained realizability. We calibrated our EARSM against a DNS of combustion in a wall-jet flow. Correct predictions of turbulent density fluxes have been achieved and essential features of the anisotropy behaviour have been captured.The proposed calibration keeps the model free of singularities for the cases studied. In addition, we have applied the EARSM to the investigation of supercritical carbon dioxide flow in an annulus. The model correctly captured mean enthalpy, temperature and density as well as the turbulence shear stress. Hence, we consider the model as a useful tool for the analysis of a wide range of compressible flows with large density variation.QC 20160314
15
Hicks, Kiley Ann. "Causes and Consequences of Mitochondrial Variation in Caenorhabditid Nematodes." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/928.
Анотація:
Mitochondria are dynamic organelles that harbor their own stream-lined genome and generate much of the ATP necessary to sustain eukaryotic life via an electron transport chain (ETC). Because of the central role for mitochondria in organismal physiology, mitochondrial genetic and phenotypic variation can alter organismal fitness and affect population genetic and evolutionary outcomes. Despite the far-reaching relevance of mitochondria to evolutionary processes and human health, we lack a basic understanding of the causes and consequences of mitochondrial genetic and phenotypic variation. In this thesis, I quantified mitochondrial reactive oxygen species (ROS), membrane potential (δΨM), and mitochondrial morphological traits within Caenorhabditis briggsae natural isolates and mutation-accumulation (MA) lines of both C. briggsae and Caenorhabditis elegans. Substantial natural variation was discovered for most mitochondrial form and function traits measured for a set of C. briggsae isolates known to harbor mitochondrial DNA structural variation in the form of a heteroplasmic nad5 gene deletion (nad5δ) that correlates negatively with organismal fitness. Most among-isolate phenotypic variation could be accounted for by phylogeographic clade membership rather than nad5δ level. Analysis of mitochondrial-nuclear hybrid strains provided support for both mtDNA and nuclear genetic variation as drivers of natural mitochondrial phenotype variation. An MA experimental approach revealed that average levels of both ROS and nad5δ heteroplasmy evolved in remarkably linear ways in C. briggsae maintained under extreme inbreeding. In particular, among C. briggsae isolates prone to acquiring the nad5δ deletion, nad5δ level increased to a plateau of ~50% during successive generations of MA treatment. Conversely, mitochondrial ROS level increased or declined in a strain-specific fashion, which also meant that the relationship between ROS and nad5δ was strain-specific. Further, all lines generated from the isolate with the highest starting level of nad5δ heteroplasmy went extinct prior to generation 20 of MA treatment. Patterns of among-line variance in ROS level were also strain-specific but generally did not conform to the canonical pattern of increasing among-line variance expected for MA experiments. MA lines of C. elegans that had previously been subjected to whole-genome sequencing were found to vary significantly in ROS levels but not in 8-oxo-dG content. Despite a significant positive correlation between 8-oxo-dG and ROS levels, no relationship between oxidative stress measures and base substitution rate or G-to-T transversion rate was revealed. Finally, analysis of patterns of phenotypic correlation for a suite of 24 mitochondrial traits measured in C. briggsae natural isolates support a role for ΔΨM in shaping mitochondrial dynamics, but no such role for mitochondrial ROS. Further, our study suggests a novel model of mitochondrial population dynamics dependent upon cellular environmental context and with implications for mitochondrial genome integrity. This work identifies extensive natural variation and capacity for evolution in organellar traits within multicellular eukaryotic species, with a central role for δΨM in mitochondrial dynamics that may have implications for evolutionary adaptation to thermal niches.
16
Thomas, Louis Ignatius Jr. "Semi-active vibration control by means of an electrorheological fluids : from robust to fuzzy control." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17252.
17
Yarlagadda, Sriram. "A Battery Management System Using an Active Charge Equalization Yechnique Based on DC-DC Converter Topology." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1306852610.
18
Näsström, David. "Flow- and concentration variation between the cylinders of a diesel engine." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10175.
Анотація:
The demands on tomorrows diesel engines regarding fuel consumption and emission levels keep getting more difficult to fulfill. Due to this fact, the control demand is getting bigger and bigger. To be able to comply with the Euro 6 standards, it is believed that engine control need to be conducted individually from cylinder to cylinder if the need for after-treatment systems should be minimized.
Scania’s approach to handle emission levels so far has been to use exhaust gas recirculation (EGR). To be able to optimize the use of EGR it is necessary to know how the inert gases, water and carbon dioxide, are distributed between the cylinders. The distribution variation become even more difficult to predict since the EGR is cooled, sometimes leading to condensation of some of the water content. The condensation of water and its behavior in the inlet manifold is studied in this thesis.
Different ways of measuring non-uniformity in the gas composition between cylinders with respect to EGR in general and water content in particular are evaluated. Using these results, measurements have been conducted on an engine and conclusions are drawn from them.
The conclusions are that uneven distribution of above all liquid water, due to puddle formation, have an impact on emission formation that should be accounted for in some of the examined operating conditions.
19
Subrenat, Albert. "Procedes de traitement d'air charge en c. O. V. Par adsorption-desorption sur tissu de carbone active." Nantes, 1999. http://www.theses.fr/1999NANT2028.
Анотація:
Ce travail a pour objet l'etude de procedes de traitement d'air charge en composes organiques volatils par adsorption-desorption sur des materiaux recents, les tissus de carbone active. Une caracterisation physique des tissus de carbone active montre que ce sont des materiaux essentiellement microporeux dont les surfaces specifiques sont elevees. Le comportement electrique de ces tissus est comparable a celui des conducteurs ohmiques classiques. Ainsi, leur chauffage par effet joule direct est envisageable comme mode de regeneration. La valeur de la resistivite electrique depend des parametres d'activation et de l'orientation du tissu. L'echauffement de ces materiaux est en general tres homogene, la distribution des temperature observee par camera infrarouge etant liee a l'heterogeneite du degre d'activation. Des donnees cinetiques et d'equilibre sont generees en reacteur discontinu. Les resultats montrent que les vitesses de transfert gaz-solide sont tres elevees, et les capacites d'adsorption importantes. La faisabilite des cycles adsorption-desorption pour des temperatures de regeneration peu elevees est demontree. La presentation sous forme de tissu permet de concevoir des adsorbeurs originaux. Ainsi des modules cylindriques plisses sont dimensionnes et utilises dans une unite pilote. L'aerodynamique de ces systemes est etudiee par la mesure des pertes de charge. Un outil de simulation numerique de l'ecoulement au travers de tels systemes est utilise pour predire les pertes de charge dans des configurations complexes et permet d'acceder au champ des pressions statiques et des vitesses. Les bonnes performances en adsorption et en desorption de ces reacteurs sont etudiees en fonction des conditions operatoires. Quelques exemples d'utilisation des tissus de carbone active dans des applications industrielles de traitement d'air sont presentees, et montrent la faisabilite du developpement industriel de tels procedes.
20
Jung, Giman. "The Charge-Relay System in Enzyme Catalysis : Construction and Function of Active Site Residues in Carboxypeptidase Y." Kyoto University, 1999. http://hdl.handle.net/2433/181885.
Анотація:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第7876号
農博第1034号
新制||農||776(附属図書館)
学位論文||H11||N3239(農学部図書室)
UT51-99-G470
京都大学大学院農学研究科農芸化学専攻
(主査)教授 林 力丸, 教授 佐藤 文彦, 教授 江崎 信芳
学位規則第4条第1項該当
21
Cament, Riveros Leonardo. "Enhancements by weighted feature fusion, selection and active shape model for frontal and pose variation face recognition." Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/132854.
Анотація:
Doctor en Ingeniería EléctricaFace recognition is one of the most active areas of research in computer vision because of its wide range of possible applications in person identification, access control, human computer interfaces, and video search, among many others. Face identification is a one-to-n matching problem where a captured face is compared to n samples in a database. In this work a new method for robust face recognition is proposed. The methodology is divided in two parts, the first one focuses in face recognition robust to illumination, expression and small age variation and the second part focuses in pose variation. The proposed algorithm is based on Gabor features; which have been widely studied in face identification because of their good results and robustness. In the first part, a new method for face identification is proposed that combines local normalization for an illumination compensation stage, entropy-like weighted Gabor features for a feature extraction stage, and improvements in the Borda count classification through a threshold to eliminate low-score Gabor jets from the voting process. The FERET, AR, and FRGC 2.0 databases were used to test and compare the proposed method results with those previously published. Results on these databases show significant improvements relative to previously published results, reaching the best performance on the FERET and AR databases. Our proposed method also showed significant robustness to slight pose variations. The method was tested assuming noisy eye detection to check its robustness to inexact face alignment. Results show that the proposed method is robust to errors of up to three pixels in eye detection. However, face identification is strongly affected when the test images are very different from those of the gallery, as is the case in varying face pose. The second part of this work proposes a new 2D Gabor-based method which modifies the grid from which the Gabor features are extracted using a mesh to model face deformations produced by varying pose. Also, a statistical model of the Borda count scores computed by using the Gabor features is used to improve recognition performance across pose. The method was tested on the FERET and CMU-PIE databases, and the performance improvement provided by each block was assessed. The proposed method achieved the highest classification accuracy ever published on the FERET database with 2D face recognition methods. The performance obtained in the CMU-PIE database is among those obtained by the best published methods. Extensive experimental results are provided for different combinations of the proposed method, including results with two poses enrolled as a gallery.
22
Wang, Jianren. "Nanostructured Redox-Active Mesoporous Silica Films Based on An Electron-Hopping Mechanism : Charge Transfer Behaviors And Energy Storage Potentials." Thesis, Université de Lorraine, 2020. http://www.theses.fr/2020LORR0216.
Анотація:
Un nouveau type de matériaux de stockage d'énergie à base de silice fonctionnant avec un mécanisme de saut d'électrons a été préparé en combinant une méthode d'auto-assemblage électrochimique (EASA) et une réaction de clic d'azide-alcyne catalysée par le cuivre (CuAAC). Les centres actifs redox (molécules de ferrocène ou de cobaltocénium) répartis à la surface du film de silice peuvent directement commuter les électrons par le biais du processus de saut d'électrons. Les résultats démontrent que ce mécanisme de transfert de charge est capable de fournir un taux de transfert d'électrons rapide même sur le substrat de silice isolant, ce qui se traduit par une performance de taux supérieure par rapport aux matériaux faradiques traditionnels. La haute densité des molécules redox et la voie de diffusion des contre-ions lisses ont été identifiées comme jouant un rôle essentiel pour assurer le processus de saut d'électrons rapide. En outre, l'assemblage à grande échelle du système de saut d'électrons a été réalisé en générant le film de silice fonctionnalisé au ferrocène sur une électrode autoportante en mousse de graphène, présentant une densité de capacité 100 fois plus élevée que celle générée sur une électrode ITO, tout en maintenant la performance de taux élevé. Enfin, une tentative a été faite pour assembler la silice fonctionnalisée au ferrocène sur un dispositif planaire flexible, et les résultats préliminaires ont prouvé la faisabilité de l'idée que nous proposons. Globalement, dans cette thèse, l'étude systématique du potentiel du processus de saut d'électrons dans le domaine du stockage de l'énergie, qui pourrait ouvrir une nouvelle voie pour la construction de matériaux de stockage de l'énergieA new type of silica-based energy storage materials operating with electron-hopping mechanism has been prepared by combining electrochemically-induced self-assembly method (EASA) and a copper-catalyzed azide-alkyne click (CuAAC) reaction. The redox active centers (ferrocene or cobaltocenium molecules) distributed on the surface of the silica film can directly commute electrons via the electron-hopping process. The results demonstrate this charge transfer mechanism is able to deliver a fast electron transfer rate even on the insulating silica substrate, resulting in a superior rate performance in comparison to the traditional faradic materials. The high density of redox molecules and the smooth counter ions diffusion pathway have been identified playing a pivotal role to ensure the fast electron-hopping process. Besides, the large-scale assembly of the electron-hopping system has been achieved by further generating the ferrocene functionalized silica film on a free-standing graphene foam electrode, exhibiting a 100-times higher capacity density, in comparison to that generating on ITO electrode, while maintaining the high rate performance. Finally, an attempt has been tried to assemble the graphene-supported ferrocene-functionalized silica into a flexible planar device, and the preliminary results has proved the feasibility of our proposed idea. Overall, in this thesis, the systematical study for the potential of the electron-hopping process in the energy storage field, which may pave a new way for the construction of energy storage materials
23
Smith, Aubrey L. "Facilitating multi-electron reactivity at low-coordinate cobalt complexes using redox-active ligands." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42745.
Анотація:
In this study, we describe a detailed investigation of cobalt complexes containing redox-active ligands. We have prepared an electronic series of the complex in three oxidation states: [CoIII(ap)2]-, CoIII(isq)(ap), and [CoIII(CH3CN)(isq)2]+. Characterization shows that the metal center remains cobalt(III) through the redox changes and indicates that the oxidation state changes occur with gain or loss of electrons from the ligand set. While CoIII(isq)(ap) reacts with halide radicals to form a new cobalt-halide bond in a single electron reaction, [CoIII(ap)2]- appears to be prone to multi-electron reactivity in reactions with sources of "Cl+". Both reactions occur with electrons derived from the ligand set. Mechanistic studies suggest a single, two electron step is responsible for the bond-formation. Similarly, [CoIII(ap)2]- reacts with alkyl halides to pseudo-oxidatively add the alkyl at the cobalt center. The product of the reaction can be isolated and fully characterized and was found to be best assigned as CoIII(alkyl)(isq)2. This assignment indicates that the reaction occurs, again, with the new bond formed with two electrons formally derived from the ligand set and with no change in oxidation state at the metal center. Mechanistic investigations of the pseudo-oxidative addition suggest the reaction is SN2-like. The reaction occurs with a wide scope of alkyl halides, including those containing beta-hydrogens.
The cross-coupling reaction of CoIII(alkyl)(isq)2 with RZnX forms a new carbon-carbon bond. Similarly, the two electron oxidized complex [CoIII(CH3CN)(isq)2]+ reacts with organozinc reagents to couple two carbon nucleophiles and form a new carbon-carbon bond. Both reactions are successful with both sp2 and sp3 carbons. When followed substoichiometrically, the homocoupling reaction can be observed to form CoIII(alkyl)(isq)2. This indicates that the homocoupling and cross-coupling reactions proceed by the same mechanism. However, both reactions have low yields. The yield of the reactions are decreased by steric bulk of the alkyl or aryl fragments or around the metal center created by substituents on the ligand. Also, while the steric congestion disfavors the addition of the first alkyl fragment, the addition of the second alkyl fragment and subsequent rapid elimination of the coupling product is almost completely inhibited. This result also implies that the coupling of the two alkyl fragments is entirely inner-sphere requiring installation of both for coupling.
In a complementary study, use of bidentate or tridentate stabilizing ligands in combination with one redox-active catechol-derived or amidophenol-derived ligand was investigated. With the synthesis of (triphos)CoII(cat) and the one electron oxidized [(triphos)CoII(sq)]+, it is evident that the oxidation occurs at the ligand and not the metal. Reaction of (triphos)CoII(cat) with a Cl+ reagent generated a new material which we tentatively describe as (triphos)CoIII(Cl)(sq). This implies that the two electrons used to create the new cobalt-halide bond are derived from both the ligand and the metal, one from each. We believe the complex is unreactive with organic halides due to the steric bulk surrounding the metal center. Similar cobalt complexes containing tridentate or bidentate phosphine ligands or a tridentate pyrazol ligand in combination with a catechol-derived or amidophenol-derived ligand resulted in unsuccessful synthesis or unstable complexes.
Throughout the course of both of these studies, steric crowding at the metal center is a problem disfavoring the facilitated reactivity. We have however shown that the amidophenol ligands have favorable molecular orbital overlap with the cobalt to act as an electron reservoir and facilitate reactivity at the metal center. We have also shown that this combination can create a proclivity to facilitate multi-electron reactions at the metal that is naturally prone to radical reactions.
24
Burgun, Alexandre. "Oxidative activation of iron- and ruthenium-alkynyl complexes : toward square-shaped molecules with four redox-active metal centres." Rennes 1, 2011. http://www.theses.fr/2011REN1S081.
25
Butz, Natalie [Verfasser], and Yiannos [Akademischer Betreuer] Manoli. "Design and implementation of cause-based and consequence-based control circuits for active charge balancing in CMOS integrated neural stimulator." Freiburg : Universität, 2021. http://d-nb.info/1240610238/34.
26
Hayakawa, Naoki, Hiroshi Inano, Yusuke Nakamura, and Hitoshi Okubo. "Time Variation of Partial Discharge Activity Leading to Breakdown of Magnet Wire under Repetitive Surge Voltage Application." IEEE, 2008. http://hdl.handle.net/2237/12126.
27
Deltenre, Pierre. "Hépatite C: contribution à l'évaluation de l'histoire naturelle et à la prise en charge thérapeutique de l'hépatite chronique." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209708.
Анотація:
L’hétérogénéité de l’histoire naturelle de l’hépatite C est expliquée par l’existence de facteurs environnementaux ou liés au malade qui influencent l’évolution de la maladie. L’obtention d’une réponse virologique soutenue est l’objectif principal de la prise en charge thérapeutique car c’est la seule façon de réduire l’incidence de la cirrhose et la mortalité liée au virus de l’hépatite C. Pour être efficaces, les stratégies thérapeutiques doivent être élaborées à deux niveaux. A l’échelle individuelle, elles doivent optimaliser les chances de réponse virologique tout en limitant l’exposition aux effets secondaires. A l’échelle d’une population, la meilleure stratégie est celle qui aura l’impact le plus important sur l’incidence de la cirrhose et sur la mortalité liées au virus de l’hépatite C.Les travaux réalisés dans le cadre de cette thèse ont permis d’identifier des critères virologiques autorisant l’arrêt d’un traitement inefficace dès le terme de la 4ème semaine chez les malades présentant des transaminases normales et chez les malades non répondeurs à un premier traitement, de quantifier la perte de chance de réponse virologique lorsque la durée du traitement est limitée à 24 semaines chez les malades infectés par un génotype 1, d’évaluer la place de l’amantadine dans l’arsenal thérapeutique, de quantifier l’impact d’une insulino-résistance sur le taux de réponse virologique, de contribuer à l’élaboration d’une stratégie thérapeutique permettant une meilleure tolérance hématologique chez les malades hémodialysés et de quantifier l’impact des polymorphismes de l’interleukine 28B sur le taux réponse virologique des malades infectés par un génotype 2 ou 3. Nos travaux ont également permis de mesurer l’impact d’une consommation excessive d’alcool sur la morbi-mortalité liée au virus de l’hépatite C à l’échelle d’une population et de quantifier l’impact des mesures thérapeutiques actuelles et de stratégies thérapeutiques alternatives sur cette morbi-mortalité.
Au cours de la prochaine décennie, le traitement de l’hépatite chronique C sera articulé autour des molécules antivirales spécifiques agissant directement contre le virus de l’hépatite C. De nouvelles stratégies thérapeutiques intégrant la cinétique virale et les marqueurs génétiques prédictifs de la réponse virologique soutenue devront être élaborées afin d’offrir les meilleures chances d’éradication virologique au plus grand nombre de malades.
Doctorat en sciences médicales
info:eu-repo/semantics/nonPublished
28
Li, Yan. "Recherche et Développement de Capteurs Actifs Monolithiques CMOS pour la Détection de Particules Elémentaires." Paris 11, 2007. http://www.theses.fr/2007PA112118.
Анотація:
Les capteurs Actifs Monolithiques CMOS rapides (MAPS) ont été étudiés au cours de ce travail dans le but d’étudier le futur détecteur de vertex du futur collisionneur linéaire ILC. Deux prototypes (MIMOSA 8 et MIMOSA 16), avec la même architecture micro-électronique, ont été développés avec deux technologies CMOS différentes et avec des épaisseurs de la couche epitaxial différentes. La taille de la matrice de pixels est 32x128: 8 colonnes de pixels en lecture directe analogique et les 24 autres colonnes sont connectées aux discriminateurs de colonne auto-zéro. La structure à Double Echantillonnage Corrélé (CDS : Correlated Double Sampling) est intégrée à l’intérieur du pixel et du discriminateur. Les pixels du type photo diode (avec tailles de diode différentes) sont utilisés. A l’aide d’une source radioactive de 55Fe, les paramètres importants du pixel, tel que Bruit Temporel, le Bruit Fixe (FPN : Fixed Pattern Noise), le rapport Signal sur Bruit (SNR : Signal-to-Noise Ratio), le facteur de conversion de charge (CVF : Charge-to-Voltage conversion Factor) et l’Efficacité de Collection de Charge (CCE), ont été étudiés en fonction de la vitesse de lecture et de la taille de la diode du pixel. L’effet de l’irradiation aux neutrons rapides a été aussi étudié. Deux campagnes de tests en faisceaux (électrons de 5 GeV et pions de 180 GeV) ont été réalisées sur MIMOSA 8. L’Efficacité de Détection et la Résolution Spatiale sont étudiées en variant le seuil du discriminateur. Pour ces deux paramètres, les influences de la taille de pixel et du niveau de SNR sur le pixel central du cluster sont aussi étudiées. Afin d’améliorer la résolution spatiale, un ADC très compact (25 µm x 1 mm) est développé sur la technologie AMS 0. 35 µm OPTO. Basée sur une architecture dite à approximation successive, des structures CDS sont aussi intégrées dans l’ADC. Les résultats préliminaires ont été obtenus. Un nouveau discriminateur de colonne auto-zéro, utilisant un latch statique, a été développé sur la même technologie. Les résultats préliminaires des tests sont également présentésIn order to develop high spatial resolution and readout speed vertex detectors for the future International Linear Collider (ILC), fast CMOS Monolithic Active Pixel Sensors (MAPS) are studied on this work. Two prototypes of MAPS, MIMOSA 8 and MIMOSA 16, based on the same micro-electronic architecture were developed in CMOS processes with different thickness of epitaxial layer. The size of pixel matrix is 32x128: 8 columns of the pixel array are readout directly with analog outputs and the other 24 columns are connected to the column level auto-zero discriminators. The Correlated Double Sampling (CDS) structures are successfully implemented inside pixel and discriminator. The photo diode type pixels with different diode sizes are used in these prototypes. With a 55Fe X ray radioactive source, the important parameters, such as Temporal Noise, Fixed Pattern Noise (FPN), Signal-to-Noise Ratio (SNR), Charge-to-Voltage conversion Factor (CVF) and Charge Collection Efficiency (CCE), are studied as function of readout speed and diode size. For MIMOSA 8, the effect of fast neutrons irradiation is also. Two beam tests campaigns were made: at DESY with a 5 GeV electrons beam and at CERN with a 180 GeV pions beam. Detection Efficiency and Spatial Resolution are studied in function of the discriminator threshold. For these two parameters, the influences of diode size and SNR of the central pixel of a cluster are also discussed. In order to improve the spatial resolution of the digital outputs, a very compact (25µmx1mm) and low consumption (300 µW) column level ADC is designed in AMS 0. 35 µm OPTO process. Based on successive approximation architecture, the auto-offset cancellation structure is integrated. A new column level auto-zero discriminator using static latch is also designed
29
Andersson, Peter. "Charge Transport Modulation and Optical Absorption Switching in Organic Electronic Devices." Doctoral thesis, Norrköping : Department of Science and Technology, Linköping University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10271.
30
Bahr, Emilie S. "Cycling in the Crescent City: An exploration of the spatial variation in bicycle commuting in New Orleans." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1607.
Анотація:
This thesis examines the spatial variation in bicycle commuting across New Orleans. It identifies where in the city bicycle commuting is most and least prevalent. It also explores factors that are promoting and discouraging utilitarian bicycling. A review of existing literature on variables found to influence transportation bicycling is conducted, and a survey is disseminated to residents across the city to determine some of the motivations for and obstacles to transportation bicycling locally. Additionally, case studies are compiled pertaining to two neighborhoods falling on opposite ends of the bike-commute spectrum. These include analysis of socio-economic and demographic data; an evaluation of the built environment using maps and field observation; and interviews to assess residents’ attitudes about and experiences with transportation bicycling. In the end, this thesis should be helpful in pinpointing variables influencing bicycle commute rates and in determining the types of policies and investments that may be most effective in encouraging more bicycling in New Orleans and across the country.
31
Darcel, Laurence. "Synthèse et réalisations de filtres actifs micro-ondes intégrés en technologie MMIC : intégration de la méthode dans un outil de CAO." Paris 6, 2005. http://www.theses.fr/2005PA066492.
32
Josse, Stève. "Transportabilité de fonctions analogiques en technologies CMOS submicroniques : application : contrôle du retard des fronts d'horloges d'un imageur CCD." Toulouse, INPT, 2003. http://www.theses.fr/2003INPT029H.
Анотація:
Dans le cadre de la transportabilité de circuits, nous étudions le transfert de circuits analogiques CMOS par une approche semi-analytique. Appliquée aux fonctions amplifications élémentaires, elle consiste à représenter graphiquement les caractéristiques de circuits normalisés afin d'en déduire un premier dimensionnement suivant les performances souhaitées. Cette approche est validée par l'étude de 2 amplificateurs opérationnels. L'écart relatif du produit gain bande passante obtenu avec celui de la simulation n'excède pas ± 20 %. Un circuit mixte pour des applications spatiales générant des retards programmables de l'ordre de la nanoseconde a été transporté dans 2 technologies. La validation expérimentale de ces 2 circuits intégrés montre les contributions importantes de la dispersion des éléments passifs et de leurs capacités parasites distribuées. Ces phénomènes sont minimisés en introduisant des commutateurs analogiques et en optimisant le dimensionnement des composants passifs.
33
Delmas, Pierre. "Génération active des déplacements d'un véhicule agricole dans son environnement." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00669534.
Анотація:
Dans ces travaux, nous proposons un système de guidage automatique pour la navigation sûre d'un robot mobile dans un monde ouvert. Le principe est de contrôler la direction et la vitesse du véhicule afin de préserver son intégrité physique et celle de son environnement. Cela se traduit par la généralisation du concept d'obstacle permettant d'estimer l'espace de vitesses admissibles par le véhicule en fonction de la surface de navigation, des capacités du véhicule et de son état. Afin d'atteindre cet objectif, le système doit pour chaque itération : 1) fournir à la tâche de perception une zone sur laquelle elle devra focaliser son attention pour la reconstruction de l'environnement ; 2) générer des trajectoires admissibles par le véhicule ; 3) estimer le profil de vitesse admissible pour chacune d'entre elles ; 4) pour finir, sélectionner la plus optimale par rapport à un critère prédéfini. Des résultats simulés et obtenus sur un démonstrateur réel permettent d'analyser les performances obtenues du système face à des scénarios divers et en démontre la pertinence.
34
Djouani, Mohamed. "Recherche d'information dans les documents numériques : vers une variation des modalités d'exécution procédurale." Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00945859.
Анотація:
L'activité de recherche d'information sur le web est devenue courante dans notre vie journalière. Malgré cela, elle pose encore de nombreux problèmes chez l'utilisateur qui ne trouve pas l'information qu'il recherche ou qui se perd devant la quantité d'informations disponible. Cette étude vise à expérimenter un nouveau dispositif de prévisualisation, breveté permettant à des utilisateurs de naviguer et de consulter des pages en profondeur. La tâche consiste à trouver un appartement cible possédant un ou plusieurs critères spécifiques dans un site web d'agence immobilière spécialement conçu. Plusieurs conditions ont été testées. L'une " habituelle " présentant les caractéristiques classiques de recherche, page par page; l'autre " transparente " qui permet de pré-visualiser les pages choisies et de ne sélectionner que les pages pertinentes. Nous nous intéressons à la mise en oeuvre des processus cognitifs ou s'ajoute l'importance du maintien du but de la recherche en mémoire de travail et aussi à la notion de charge cognitive investie dans une telle activité. Nous utilisons entre autres la technique des mouvements oculaires qui permet de déterminer comment un utilisateur traite et recherche des informations dans un document numérique. Par ailleurs, nous comparons les performances de ce dispositif avec une tablette tactile. Les résultats obtenus révèlent des effets significatifs de ce dispositif de prévisualisation.
35
McBeth, Rafe A. "Active Radiation Detectors for Use in Space Beyond Low Earth Orbit| Spatial and Energy Resolution Requirements and Methods for Heavy Ion Charge Classification." Thesis, Colorado State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10604769.
Анотація:
Space radiation exposure to astronauts will need to be carefully monitored on future missions beyond low earth orbit. NASA has proposed an updated radiation risk framework that takes into account a significant amount of radiobiological and heavy ion track structure information. These models require active radiation detection systems to measure the energy and ion charge Z.
However, current radiation detection systems cannot meet these demands. The aim of this study was to investigate several topics that will help next generation detection systems meet the NASA objectives. Specifically, this work investigates the required spatial resolution to avoid coincident events in a detector, the effects of energy straggling and conversion of dose from silicon to water, and methods for ion identification (Z) using machine learning.
The main results of this dissertation are as follows: 1. Spatial resolution on the order of 0.1 cm is required for active space radiation detectors to have high confidence in identifying individual particles, i.e., to eliminate coincident events. 2. Energy resolution of a detector system will be limited by energy straggling effects and the conversion of dose in silicon to dose in biological tissue (water). 3. Machine learning methods show strong promise for identification of ion charge (Z) with simple detector designs.
36
Dawson, Jill Margaret. "Variation in sexual behaviour, use of HIV testing and other health care facilities amongst homosexually active men in response to HIV/AIDS." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358631.
37
Ghanem, Mahmoud. "On the Mechanistic Roles of the Protein Positive Charge Close to the N(1)Flavin Locus in Choline Oxidase." Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/chemistry_diss/3.
Анотація:
Choline oxidase catalyzes the oxidation of choline to glycine betaine. This reaction is of considerable medical and biotechnological applications, because the accumulation of glycine betaine in the cytoplasm of many plants and human pathogens enables them to counteract hyperosmotic environments. In this respect, the study of choline oxidase has potential for the development of a therapeutic agent that can specifically inhibit the formation of glycine betaine, and therefore render pathogens more susceptible to conventional treatment. The study of choline oxidase has also potential for the improvement of the stress resistance of plant by introducing an efficient biosynthetic pathway for glycine betaine in genetically engineered economically relevant crop plant. In this study, codA gene encoding for choline oxidase was cloned. The cloned gene was then used to express and purify the wild-type enzyme as well as to prepare selected mutant forms of choline oxidase. In all cases, the resulting enzymes were purified to high levels, allowing for detailed characterizations. The biophysical and biochemical analyses of choline oxidase variants in which the positively charged residue close to the flavin N(1) locus (His466) was removed (H466A) or reversed (H466D) suggest that in choline oxidase, His466 modulates the electrophilicity of the bound flavin and the polarity of the active site, and contributes to the flavinylation process of the covalently bound FAD as well as to the stabilization of the negative charges in the active site. Biochemical, structural, and mechanistic relevant properties of selected flavoproteins with special attention to flavoprotein oxidases, as well as the biotechnological and medical relevance of choline oxidase, are presented in Chapter I. Chapter II summarizes all the experimental techniques used in this study. Chapter III-VII illustrate my studies on choline oxidase, including cloning, expression, purification and preliminary characterizations (Chapter III), spectroscopic and steady state kinetics (Chapter IV), the catalytic roles of His466 and the effects of reversing the protein positive charge close to the flavin N(1) locus (Chapter V and VI), and the roles of His310 with a special attention to its involvement in a proton-transfer network (Chapter VII). Chapter VIII presents a general discussion of the data presented.
38
Ferreira, de Sousa Marcus Alexandre. "Contribution à la conception de lois de commande à caractère robuste pour une machine synchrone entraînant une charge élastique à inertie variable." Phd thesis, Toulouse, INPT, 2007. http://oatao.univ-toulouse.fr/7601/1/ferreira.pdf.
Анотація:
Le but de ce travail est de définir les règles de synthèse de différentes lois de commande afin de leur donner un caractère robuste. Nous étudions la problématique du contrôle d'un actionneur synchrone en présence d'une charge mécanique. Cette charge est entraînée par un accouplement élastique et présente une valeur d'inertie variable et bornée. La synthèse de correcteurs simples est présentée et des méthodes pour obtenir le meilleur correcteur sur l'intervalle de variation des paramètres sont presentées. Nous avons présenté dans ce travail, les règles de synthèse d'un régulateur PID sur lequel nous avons ajouté une méthode itérative d'optimisation basée sur l'expertise du comportement du système ainsi qu'un algorithme génétique. Cette partie a permis de donner des règles simples de synthèse et de paramétrisation de la méthode d'optimisation afin de trouver les 3 degrés de liberté de correction optimaux. La synthèse de correcteurs dans l'espace d'état a ensuite été abordée en étudiant le meilleur placement de pôle en fonction de l'élasticité et de la variation d'inertie. La méthode de synthèse par optimisation d'un critère quadratique intégrale (LQI) est largement presentée. Cette partie permet de donner les lignes directrices et les critères à choisir pour obtenir un placement de pôle respectant au mieux le cahier des charges et un comportement robuste aux variations de paramètres. L'étude de la méthode LQI à 3 degrés de liberté à permis de lier la valeur des coefficients aux pôles et au comportement du système en boucle fermée. Une deuxième méthode de synthèse par optimisation LQI permet de définir les gains du régulateur à partir d'un placement de pôles souhaité. Toutes ces structures de contrôle ont été vérifiées en simulation en tenant compte du pilotage de la machine synchrone au travers de son convertisseur statique. Les boucles internes de gestion des rapports cycliques et des boucles de courant sont présentées de manière à expliquer certain phénomène et afin de fixer correctement les dynamiques internes souvent négligées. Ces correcteurs ont ensuite été implanté dans un environnement dSPACE, sur un banc d'essai constitué d'un convertisseur MLI, d'un actionneur synchrone autopiloté entraînant une charge mécanique identique au problème évoqué présentant un accouplement élastique et des disques additionnels permettant la variation d'inertie. Une extension vers des correcteurs plus avancés sont présentés en mettant l'accent sur les difficultés qui apparaissent pour la représentation des systèmes (mathématique et forme augmentée pour les approches H1, LMI, réduction de modèle, etc) sur la complexité des méthodes de recherche de solution (Riccati, inégalités matricielles contraintes, etc). Finalement une perspective mélangeant l'effet des correcteurs et des observateurs est brièvement présentée au travers de la méthode LQI et d'un observateur d'état et de perturbation. Des résultats de simulation et d'expérimentation encourageants sont également présentés tout en conservant des règles de synthèse simples et liées à la connaissance du comportement du système.
39
Coupat, Jean-Marc. "Synthèse expérimentale d'impédances par la technique de la charge active : application à la conception d'un système de caractérisation de composants microondes de puissance fortement désadaptés." Limoges, 1994. http://www.theses.fr/1994LIMO0026.
Анотація:
La realisation d'un systeme de caracterisation experimentale de transistors microondes de puissance fortement desadaptes constitue l'objet de cette these. Les impedances de charge des composants sous test sont synthetises electroniquement et se repartissent naturellement dans la zone de fonctionnement optimal du composant (puissance ajoutee maximum, rendement en puissance ajoutee maximum,). En outre, les risques de deterioration du transistor sont tres largement diminues. La caracterisation du dispositif non lineaire est precise, fiable, rapide et la methodologie mise en uvre est independante de la frequence de travail, des conditions de polarisation, de la nature du composant (mesfet, hfet, hemt, mosfet, hbt,), des impedances d'entree et de sortie et des niveaux de puissance de sortie. Ce systeme presente est bien approprie au developpement d'un banc de caracterisation experimentale fort signal de type multiharmonique
40
Martinez, Laurent. "Intérêt de la compression-décompression active dans la prise en charge des arrêts cardio-ventilatoires extra-hospitaliers par le SMUR du bataillon de marins pompiers de Marseille." Montpellier 1, 1995. http://www.theses.fr/1995MON11097.
41
Li, Shuo. "CMOS Receiver Design for 802.11ac Standard Using Offline Calibrated Active Inductor Based Band Pass Filter in 90 nm Technology." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1576887184235935.
42
Cao, Weimin. "Adsorption of surface active elements on the iron (100) surface a study based on ab initio calculations /." Licentiate thesis, Stockholm : Skolan för industriell teknik och management, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11234.
43
Danilovic, Milisav. "Active Source Management to Maintain High Efficiency in Resonant Conversion over Wide Load Range." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/76618.
Анотація:
High-frequency and large amplitude current is a driving requirement for applications such as induction heating, wireless power transfer, power amplifier for magnetic resonant imaging, electronic ballasts, and ozone generators. Voltage-fed resonant inverters are normally employed, however, current-fed (CF) resonant inverters are a competitive alternative when the quality factor of the load is significantly high. The input current of a CF resonant inverter is considerably smaller than the output current, which benefits efficiency. A simple, parallel resonant tank is sufficient to create a high-power sinusoidal signal at the output. Additionally, input current is limited at the no-load condition, providing safe operation of the system. Drawbacks of the CF resonant inverter are associated with the implementation of the equivalent current source. A large input inductor is required to create an equivalent dc current source, to reduce power density and the bandwidth of the system. For safety, a switching stage is implemented using bidirectional voltage-blocking switches, which consist of a series connection of a diode and a transistor. The series diode experiences significant conduction loss because of large on-state voltage. The control of the output current amplitude for constant-frequency inverters requires a pre-regulation stage, typically implemented as a cascaded hard-switched dc/dc buck converter. The pre-regulation also reduces the efficiency.
In this dissertation, a variety of CF resonant inverters with two input inductors and two grounded switches are investigated for an inductive-load driver with loaded quality factor larger than ten, constant and high-frequency (~500 kHz) operation, high reactive output power (~14 kVA), high bandwidth (~100 kHz), and high efficiency (over 95 %). The implementation of such system required to question the fundamental operation of the CF resonant inverter. The input inductance is reduced by around an order of magnitude, ensuring sufficient bandwidth, and allowing rich harmonic content in the input current. Of particular importance are fundamental and second harmonic components since they influence synchronization of the zero-crossing of the output voltage and the turn-on of the switches. The synchronization occurs at a particular frequency, termed synchronous frequency, and it allows for zero switching loss in the switches, which greatly boosts efficiency. The synchronous conditions were not know prior this work, and the dependence among circuit parameters, input current harmonics, and synchronous frequency are derived for the first time. The series diode of the bidirectional switch can reduce the efficiency of the system to below 90 %, and has to be removed from the system. The detrimental current-spikes can occur if the inverter is not operated in synchronous condition, such as in transients, or during parametric variations of the load coil. The resistance of the load coil has a wide variance, five times or more, while the inductance changes as well by a few percent. To accommodate for non-synchronous conditions, a low-loss current snubber is proposed as a safety measure to replace lossy diodes. The center-piece of the dissertation is the proposal of a two-phase zero-voltage switching buck pre-regulator, as it enables fixed frequency and synchronous operation of the inverter under wide parametric variations of the load. The synchronous operation is controlled by phase-shifting the switching functions of the pre-regulator and inverter. The pre-regulator reduces the dc current in the input inductors, which is a main contributor to current stress and conduction losses in the inverter switches. Total loss of the inverter switches is minimized since no switching loss is present and minimal conduction losses are allowed. The dc current in the input inductors, once seen as a means to transfer power to load, is now contradictory perceived as parasitic, and the power is transferred to the load using a fundamental frequency harmonic! The input current to the resonant tank, previously designed to be a square-wave, now resembles a sine-wave with very rich harmonic content. Additionally, the efficiency of the pre-regulator at heavy-load condition is improved by ensuring ZVS for with an additional inductive tank.
The dissertation includes five chapters. The first chapter is an introduction to current-fed resonant inverters, applications, and state-of-the-art means to ensure constant frequency operation under load's parametric variations. The second chapter is dedicated to the optimization of the CF resonant inverter topology with a dc input voltage, two input inductors, and two MOSFETs. The topology is termed as a boost amplifier. If the amplifier operates away from the synchronous frequency, detrimental current spikes will flow though the switches since the series diodes are eliminated. Current spikes reduce the efficiency up to few percent and can create false functioning of the system. Operation at the synchronous frequency is achieved with large, bulky, input inductors, typically around 1-2 mH or higher, when the synchronous frequency follows the resonant frequency of the tank at 500 kHz. The input inductance cannot be reduced arbitrarily to meet the system bandwidth requirement, since the synchronous frequency is increased based on the inductance value. The relationship between the two (input inductance and the synchronous frequency) was unknown prior this work. The synchronous frequency is determined to be a complicated mathematical function of harmonic currents through the input inductors, and it is found using the harmonic decomposition method. As a safety feature, a current snubber is implemented in series with the resonant tank. Snubber utilizes a series inductance of cable connection between the tank and the switching stage, and it is more efficient than the previously employed series diodes. Topology optimization and detailed design procedure are provided with respect to efficiency and system dynamics. The mathematics is verified by a prototype rated at 14 kVA and 1.25 kW. The input inductance is reduced by around an order of magnitude, with the synchronous frequency increase of 2 %. The efficiency of the power amplifier reached 98.5 % and might be improved further with additional optimization. Silicon carbide MOSFETs are employed for their capability to operate efficiently at high frequency, and high temperature.
The third chapter is dedicated to the development of the boost amplifier's large signal model using the Generalized State-space Averaging (GSSA) method. The model accurately predicts amplifier's transient and steady-state operation for any type of input voltage source (dc, dc with sinusoidal ripple, pulse-width modulated), and for either synchronous or non-synchronous operating frequency. It overcomes the limitation of the low-frequency model, which works well only for dc voltage-source input and at synchronous frequency. As the measure of accuracy, the zero-crossing of the resonant voltage is predicted with an error less than 2° over a period of synchronous operation, and for a range of interest for input inductance (25 μH – 1000 μH) and loaded-quality factor (10 – 50). The model is validated both in simulation and hardware for start-up transient and steady-state operation. It is then used in the synthesis of modulated output waveforms, including Hann-function and trapezoidal-function envelopes of the output voltage/current.
In the fourth chapter, the GSSA model is employed in development of the PWM compensation method that ensures synchronous operation at constant frequency for the wide variation of the load. The boost amplifier is extended with a cascaded pre-regulator whose main purpose is to control the output resonant voltage. The pre-regulator is implemented as two switching half-bridges with same duty-cycle and phase-shift of 180°. The behavior of the cascaded structure is the same as of the buck converter, so the half-bridges are named buck pre-regulators. ZVS operation is ensured by putting an inductive tank between the half-bridges. Each output of half-bridges is connected to each of input inductors of the boost to provide the PWM excitation. Using the GSSA model, the synchronous condition and control laws are derived for the amplifier. Properties of the current harmonics in the input inductors are well examined. It is discovered that the dc harmonic, once used to transfer power, is unwanted (parasitic) since it increases conduction loss in switches of the boost. A better idea is to use the fundamental harmonic for power transfer, since it does not create loss in the switches. Complete elimination of the dc current is not feasible for constant frequency operation of the amplifier since the dc current depends on the load coil's resistance. However, significant mitigation of around 55 % is easily achievable. The proposed method improves significantly the efficiency of both the buck pre-regulator and the boost. Synchronous operation is demonstrated in hardware for fixed switching frequency of 480 kHz, power level up to 750 W, input voltage change from 300 V to 600 V, load coil's resistance change of three times, and load coil's inductance change of 3.5 %. Measured efficiency is around 95 %, with a great room for improvements. Chapter five summarizes key contributions and concludes the dissertation.Ph. D.
44
Pouchkova, Meyer Svetlana. "Vers un dictionnaire des mots à Charge Culturelle Partagée comme voie d'accès à une culture étrangère (FLE) : le cas des apprenants immigrés adultes multiculturels." Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/POUCHKOVA_MEYER_Svetlana_2010.pdf.
Анотація:
La culture comportementale du plus grand nombre ne parvient pas à se faire reconnaitre et à s'imposer auprès de la culture savante d'une minorité. Cette culture est appelée par R. GALISSON « partagée» parce que l'immense majorité des natifs la maitrisent. Elle n'est enseignée nulle part, mais acquise, hors de l'école, au cours des événements quotidiens. Cependant, elle est essentielle parce qu'elle sert à la fois: De signe de reconnaissance tacite entre tous les individus qui se réclament de la même identité collective ; De modèle de conditionnement dans les situations grégaires de la vie courante ; D'ingrédient de convivialité, c'est-à-dire de commun dénominateur pour mieux se comprendre et s'accepter. Si cette culture primordiale est acquise par les locuteurs natifs, elle pourrait être apprise par les apprenants étrangers, donc décrite, et enseignée en cours de FLE. Et ce à travers l'étude de certains mots, nommés les mots à Charge Culturelle Partagée où elle se dépose avec prédilection. Ces mots pourraient être inventoriés, définis et consignés dans un dictionnaire dit de culture partagée. Ainsi ce dictionnaire aurait pour objet est de rendre compréhensible à des apprenants étrangers le discours et le comportement général des locuteurs natifs françaisThe culture of comportment of the majority can 't try to get the confession in the society side by side with the scientific culture. The French linguist R. GALISSON called this culture as "generally accepted", so the majority bearers of language posses il. It is nowhere studied, it is taken outside of school during the process of the daily life. Nevertheless, it is very important because it indicates at the same time: The sign of identify between people who rank themselves among the same society; The model of socio- cultural comportment (the conditional model) in the daily life's situations; The sign of benevolence or, in the other words, the common denominator for the best comprehension and tolerance. If this the most important culture is acquired by the bearers of language during the everyday life, it can be described and studied by the foreign students at the French lessons. Lt takes place thanks to the specific words which carry the vast layer of the "generally accepted" culture. These words must be defioed and entered in the special cultural dictionary, the purpose of which is to facilitate the perception of the socio- cultural component in the discourse and the comportment of the bearers oflanguage for the foreign students
45
Mercier, Charles Symphorien. "Evaluations de la prise en charge multidisciplinaire en hospitalisation complète de l'adolescent obèse : apports de l'étude de la variation du métabolome et recherche de marqueurs précoces du pronostic." Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX20671/document.
Анотація:
L’obésité de l’enfant et de l’adolescent constitue un problème de santé publique important auquel sont confrontés depuis les années 1970 tous les pays industrialisés. Son origine multifactorielle, l’absence de médicaments présentant une balance bénéfice/risque favorable et l’absence de recommandations quant à la chirurgie bariatrique en font un problème thérapeutique complexe. Ceci a induit une grande variété de prises en charge thérapeutiques dont la comparaison reste difficile en absence de critère permettant de juger de leur efficacité. Ce travail avait pour but de déterminer l’efficacité d’une prise en charge multidisciplinaire dans le Centre « Les Oiseaux » pendant 8 mois, en hospitalisation complète. Une étude rétrospective incluant 1063 patients entre 1991 et 2007 a été réalisée. 746 sujets ont retourné le questionnaire 2 ans après leur sortie et 185 sujets, 5 ans après. Parmi eux plus de 75 % ont maintenu durablement au moins la moitié de leur perte de poids.Dans le but de retrouver des marqueurs précoces d’efficacité thérapeutique, nous avons aussi suivi une cohorte de 16 adolescentes et mis en place un programme de monitorage de 895 variables, données cliniques, psychologiques et biologiques ainsi que des données de pratique d’activité physique. Chaque variable a été testée pour son caractère discriminant et sa faisabilité. Une approche de métabolomique par empreintes a été mise en place sur des échantillons urinaires. Par analyse multivariée, nous avons pu montrer que le maintien 6 mois après la sortie, de la perte de poids était positivement corrélé avec la prise en charge psychologique, l’implication familiale et la capacité de conserver une activité physique suffisante, elle même sous-tendue par l’amélioration de l’estime de soiObesity in childhood must be considered as a major issue in Public Health. Since the 1970s, all developed countries must have faced an increasing prevalence of this metabolic disorder. However since the epidemic of obesity has multifactorial causes, and without the availability of a positive benefit/risk balance for chemical drugs and clear-cut indications for bariatric surgery, it is easy to understand that obesity is a complex issue. This complexity induced different schemes of care the comparison of which is made difficult by the absence of clear criteria for judging therapeutic efficacy. This work was aimed to determine the efficacy of a 8-months residential treatment program performed by a multidisciplinary team in the Care Centre “Les Oiseaux”. In order to demonstrate whether the treatment was of benefit for the patients, 1063 of those treated between 1991 and 2007 have been included in a retrospective study. 746 patients returned the questionnaire after 2 years and 185 patients, 5 years later. Among these patients 75 % were actually able to control their weight since they maintained at least half their weight loss. To unveil early parameters of therapeutic efficacy, we have set up a monitoring record of more than 895 clinical, psychological, and biological parameters as well as an accurate recording of the physical activity of adolescents during their stay in the Care Centre. In addition a metabolic profiling of urine samples has been performed. Each parameter was tested for its discrepancy power as well as its practical aspects. Sixteen female adolescents have then been followed for the duration of their stay according to our monitoring program. By multivariate analysis, we deduced that the maintaining of their weight loss was positively correlated with the psychological care, the family involvement, as well as the ability to keep a sufficient physical activity, which was sustained by the recovery of their self-esteem
46
Johansson, Arvid. "Aktivt Pansar : Att nå verkan med dagens vapensystem i morgondagens pansar." Thesis, Försvarshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-4642.
Анотація:
Då dagens vapensystem blir allt effektivare med högre penetration och större verkan är det inte längre möjligt att endast lägga på mer pansar för att få tillräckligt skydd. Fordonen blir för tunga och rörligheten påverkas negativt i allt för stor grad, därför börjar nu system för aktivt skydd slå sig in på marknaden. Dessa system söker aktivt av fordonets omgivning och skjuter ner inkommande hot såsom raketer och robotar och finns redan implementerade i en rad länder i vårt närområde. Infanteriets huvudbeväpning, som mot bepansrade hot traditionellt sett varit just robotar, raketer och granater, är i många fall verkanslös i mötet med aktivt pansar. Uppsatsen undersöker vilka möjligheter som finns att med den utrustning som dagens svenska försvarsmakt är utrustad med nå verkan i mål som är skyddade av aktivt pansar. De befintliga systemen för aktivt pansar Trophy, Iron Curtain och Arena har valts som exempelsystem. De vapensystem som granskas är STRIX, Rb56, Pskott m/86, Grg m/86 samt fordonsmina 14. En slutsats är att de granskade systemen alla saknar förmåga att skydda fordonet från hot som kommer rakt ovanifrån, detta medför att STRIX är fullt fungerande mot ett fordon skyddat av aktivt pansar.Since today's weapons systems are becoming more efficient with higher penetration and greater efficacy, it is no longer possible to only put on more armor to get adequate protection. The vehicles become too heavy and mobility is adversely affected to an excessive degree, because of this systems for active protection are now breaking into the market. These systems are actively scanning the vehicle's surroundings and shoot down incoming threats such as rockets and robots and are already implemented in a number of countries in our region. The infantry's main armament against armored units, which traditionally have been just missiles, rockets and grenades are in many cases useless meeting with active protection systems. The paper examines the possibilities of reaching effect in targets equipped with active armor using the equipment available to the Swedish armed forces today. The existing active protection systems Trophy, Iron Curtain and Arena have been chosen as example systems. The weapons systems examined are STRIX , Rb56 , Pskott m/86 , Grg m/86 and Fordonsmina 14. One conclusion is that the audited systems all lack the ability to protect the vehicle from threats that come from directly above; this means that STRIX is fully functional to a vehicle protected by an active protection system.
47
Cardwell, Drew. "Investigation of electrically-active defects in AlGaN/GaN high electron mobility transistors by spatially-resolved spectroscopic scanned probe techniques." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1373894407.
48
Dubost-Fontaine, Véronique. "Effets induits par une tâche attentionnelle sur la marche humaine : rôle respectifs de la variation de la vitesse de marche et de la charge attentionnelle sur la variabilité du pas." Saint-Etienne, 2005. http://www.theses.fr/2005STET007T.
Анотація:
La marche humaine est bien souvent considérée comme une activité motrice " automatique " qui dépend d'un contrôle sous-cortical et spinal, sous-entendant une faible participation des ressources attentionnelles, tout au moins chez l'adulte jeune. Avec l'âge, on observe une évolution des paramètres spatio-temporels de la marche liée à une modification de son contrôle, avec notamment la perte de son caractère automatique et la mise en jeu croissante des ressources attentionnelles. L'étude de la mise en jeu de l'attention dans la marche présente un intérêt tout particulier dans l'évaluation du risque de chute du sujet âgé et peut être réalisée via des paradigmes de double-tâche. Si les modifications de la valeur moyenne des paramètres spatio-temporels sont bien connues, leur variabilité d'un cycle à l'autre a été moins étudiée, alors qu'il s'agit d'un marqueur sensible du contrôle de la marche par le système nerveux central. Une forte variabilité du pas est le témoin de la mise en jeu du cortex sous la forme de ressources attentionnelles. Cependant des précautions doivent être prises dans l'interprétation de la valeur de la variabilité du pas car celle-ci peut également dépendre en partie de la vitesse de marche. Plusieurs études ont démontré que la variabilité du temps du pas augmentait lorsque la vitesse de marche diminuait. Hors, sous condition de double-tâche, la majorité des études montrent une réduction plus ou moins importante de la vitesse de marche. Ainsi, le travail de recherche que nous présentons a pour objectifs de répondre aux deux questions suivantes : 1) Quelle est l'influence de la vitesse de marche dans la valeur de la variabilité du temps du pas ? et 2) L'attention est-elle mise en jeu dans le contrôle du rythme de la marche chez le sujet jeune ? Pour répondre à ces deux questions, nous avons utilisé un paradigme de double-tâche combinant la marche à une tâche de décompte ou de fluence verbale, en analysant d'une part la performance à la tâche cognitive, et d'autre part la variabilité du temps du pas, en tenant compte de la vitesse du pas comme facteur de confusion potentiel. Quelque soit le groupe de sujets testés et la tâche cognitive utilisée, les résultats obtenus montrent une modification de la marche sous double-tâche avec notamment une réduction de la vitesse de marche (liée à l'augmentation du temps du pas) et une augmentation de la variabilité du temps du pas. Cette dernière, indépendante de la vitesse de marche, nous a permis de démontrer que le contrôle du caractère rythmique de la marche sollicite les ressources attentionnelles chez le sujet âgé, comme chez le sujet jeuneHuman walking is considered as an automatic motor activity which is controlled by the subcortical and spinal regions, involving few attentional resources. Age-related changing of spatio-temporal gait parameters has been related to the loss of the automatic caracter of gait control and involvement of attentionnal control. The study of the relationship between attention and gait control is interesting to evaluate the risk of falls in older adults and may be obtained using dual-task paradigms. Mean gait parameters are well known, however, stride-to-stride variability has been less studied, in spite of the gait variability is a sensitive marker reflecting the control of gait by the CNS. A high variability is used as a clinical index of gait unsteadiness in relation with attentional control of the cortical regions. There are several validity concerns related to the methodology used to study locomotor control. The most common concern consists of the association of stride variability with stride velocity of the tested subjects. Stride velocity has been demonstrated to influence stride time variability. Because stride velocity often decreases under dual-task condition, the dual-task related increase in stride time variability therefore could be provoked by either the decrease in walking speed, the attention-demanding task itself, or both. Thus, the aims of this study is to answer to the following questions: 1) What is the influence of gait velocity on stride-to-stride variability? and 2) Is attention required to control the rhythmic steping mechanism of walking in helathy young adults? We used a dual-task paradigm, i. E. Gait while backward counting or gait while verbal fluency task, and analysed both cognitive performance and gait parameters, adjusted for gait velocity. Whatever the subject's group and the nature of the attentional task tested, our results showed dual-task related changes, especially, gait velocity decrease (in relation with stride time increase), and stride time variability increase. This increased variability under dual-task was not related to the decrease of stride velocity, thus demonstrating the attentional control of the rhythmic stepping mechanism not only in older adults, but also in healthy young adults
49
Chocron, Richard. "Analyse de l'influence des modalités de prise en charge sur le pronostic des patients victimes d'un arrêt cardiaque extra-hospitalier." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCB015.
Анотація:
Le pronostic de l’arrêt cardiaque extrahospitalier (ACEH), ne dépassant pas 8 % de survie globale en France. Ce taux de survie varie considérablement en fonction des régions mais aussi en fonction des établissements hospitaliers. La survie de ces patients repose sur les éléments de la prise en charge initiale et sur la qualité des soins prodigués pendant la phase post-arrêt cardiaque. Parallèlement, l’influence du niveau de ressources des prises en charge à la fois pré-hospitalières (Pompiers, SAMU) et intra-hospitalières (réanimations) sur le pronostic global, reste encore peu explorée. L’objectif de ce travail a été d’analyser l’influence du niveau de ressources des différentes étapes de la prise en charge, pré-hospitalière et intra-hospitalière, sur le pronostic des patients victimes d’un ACEH. Méthode : depuis Mai 2011, le registre du centre d’expertise de la mort subite collecte l’ensemble des cas d’ACEH survenant sur le territoire de Paris et sa petite couronne. Les caractéristiques socio-démographiques et, les critères d’Utstein sont prospectivement recueillis. Pour étudier la relation entre le niveau de ressources de la phase pré-hospitalière et hospitalière, et le pronostic (RACS et survie à la sortie de l’hôpital), nous avons utilisé principalement les méthodes de régression logistique et hiérarchique ajustées sur les facteurs pronostiques de l’ACEH. Les centres hospitaliers receveurs des ACEH ont été classés en trois catégories : centre A (grand volume d’activité et accès 24/7 à un plateau de coronarographie) ; centre B (volume d’activité intermédiaire et accès partiel à un plateau de coronarographie) et centre C (faible niveau d’activité et pas d’accès à un plateau de coronarographie). De même, la zone du Grand Paris a été divisé en 19 aires géographiques au sein desquelles le niveau de ressources pré-hospitalières (premiers secours et secours médicalisés) sont homogènes. Résultats : entre mai 2011 et décembre 2013, 1476 patients ont été admis vivants après un ACEH dans les 48 centres hospitaliers de la zone du Grand Paris. La survie globale à la sortie de réanimation a été de 30%. Les caractéristiques initiales des patients ont significativement varié selon les centres receveurs ; les centres du groupe A ont reçu ainsi des patients plus jeunes, avec une proportion plus importante de rythme initial choquable (p<0.001). Le taux de survie brut a significativement varié entre les 3 groupes (respectivement 34%, 25% and 15,4% pour A, B, C, p<0,01). Dans l’analyse multivariée, la catégorie du centre receveur n’était plus associée à la survie. Entre mai 2011 et janvier 2016, 8754 ACEH non traumatiques sont survenus dans le Grand Paris. Le taux de RACS a varié de été de de 33% à 51,1% et la survie de 4,4% à 14,5 %, selon la zone géographique (p<0.001). Les caractéristiques sociodémographiques des patients ont significativement varié entre les 19 zones géographiques (p de tendance < 0,001). Après ajustement, une densité plus importante en ressources pré-hospitalières était associée au RACS (aOR=1,21 (1,04-1,41) et aOR=1,31 (1,14-1,51); p<0,001 ; respectivement pour les premiers secours et les unités médicalisées). Seul le niveau de ressources en unité pré-hospitalières médicalisées était significativement associé à la survie à la sortie de l’hôpital. (aOR= 1,30 (1,06-1,59) p=0,01). Conclusion : il existe une grande variabilité du taux brut de survie intra-hospitalière et du pronostic au sein du Grand Paris. De plus, le niveau de ressources pré-hospitalières médicalisées était associé au pronostic contrairement au type de centre receveur, résultat pouvant découler d’une stratégie du triage médical pré-hospitalier ciblée et efficace. Nos résultats suggèrent qu’une adaptation territoriale ciblée du niveau de ressources médicales pré-hospitalières et la mise en place d’une stratégie de triage ciblé sur le profil du patient pourrait atténuer les disparités du pronostic des patients victimes d’un ACEHDespite efforts to improve the treatment of OHCA, in France the survival rate is stable around 8%. The Outcome depends mainly on the efficiency of the chain of survival of cardiac arrest7. All links of the chain of survival are crucial in order to provide optimum medical care. Being the last link of this chain, post-cardiac arrest (PCA) care is nowadays considered as an important determinant of outcome for patients with sustained return of spontaneous circulation (ROSC). The emergency medical service (EMS) response is also recognized as a key element. The number of ambulances providing basic life support (BLS) and advanced life support (ALS), is crucial to provide primary care. In OHCA patients with sustained (ROSC), current evidence demonstrates considerable variability in survival rates across receiving hospital and according to characteristics of neighborhoods without possibility to discern the respective influence of patients’ profile or the potential role of Emergency Medical Service (EMS) organization. Using a population-based registry serving a large population in the Greater Paris area, we aimed to assess the influence of care level center and the influence of allocated ambulance resources on outcome in OHCA patients. Method: We retrospectively analyzed a Utstein and in-hospital data prospectively collected for all non-traumatic OHCA patients from a large metropolitan area (Great Paris). Cases were geocoded according to 19 neighborhoods and the number of BLS (firefighters performing cardiopulmonary resuscitation and applying automated external defibrillator) and ALS ambulances (medicalized team providing advanced care) was collected. Receiving hospitals were categorized in 3 groups as follows: A centers (high-case volume with cath-lab 24/7), B centers (intermediate-case volume with cath-lab partly available) and C centers (low-case volume and no cath-lab). We assessed the respective influence of Utstein parameters, socio-economic characteristics and ambulance resources using a mixed-effect model with ROSC as the primary endpoint and survival at hospital discharge as a secondary endpoint. Results: Between May 2011 and December 2013, 1476 patients were admitted in 48 hospitals. Overall survival rate at discharge was 30%. Patients’ baseline characteristics significantly differed, as hospitals from group A received younger patients with a higher rate of shockable cardiac rhythms (p<0.001). Unadjusted survival rate differed significantly among the 3 groups of hospitals (respectively 34%, 25% and 15.4% for A, B, C, p<0.01). In multivariate analysis, the category of receiving hospital was no longer associated with survival. From May 2011 to January 2016, 8754 non-traumatic OHCA occurred in the Greater Paris area. Overall ROSC and survival rate at hospital discharge ranged from 33% to 51.1% and from 4.4% to 14.5 % respectively, according to neighborhoods (p<0.001). Patients’ and socio-demographics’ characteristics significantly differed between neighborhoods (p for trend< 0.001). After adjustment, a higher density of ambulances was associated with successful ROSC (respectively aOR=1.31 (1.14-1.51); p<0.001 and aOR=1.21 (1.04-1.41); p=0.01 for ALS and BLS ambulances respectively). Regarding survival at discharge, only the number of ALS ambulances >1.5 per neighborhood was significant (aOR= 1.30 (1.06-1.59) p=0.01). Conclusion: First, we observed wide disparities in crude in-hospital survival rate in the Greater Paris. After adjustment, the level of medical resources (ALS) was associated with prognosis. In addition, the type of receiving center no longer influenced either survival or neurological prognosis, which could result from a targeted EMS triage strategy. Our results suggest that a territorial adaptation in EMS resources and the implementation of a targeted triage strategy based on the patient's profile may be used in order to reduce disparities in prognosis of patients with OHCA
50
Diguisto, Caroline. "Prise en charge anténatale et conséquences néonatales chez les enfants nés extrêmes prématurés en France Providing active antenatal care depends on the place of birth for extremely preterm births: the EPIPAGE 2 cohort study Neonatal outcomes in extremely preterm newborns admitted to intensive care after no active antenatal management: a population-based cohort study." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCB001.
Анотація:
Les taux de survie des enfants nés entre 22 et 26 semaines d’aménorrhée (SA), appelés extrêmes prématurés, sont plus faibles en France qu’en Angleterre, en Suède aux États-Unis ou au Japon. Ces différences de survie pourraient être liées à des différences de pratiques autour de la naissance et en particulier à des différences de pratiques anténatales. En cas de naissances prématurées les obstétriciens, premiers interlocuteurs des femmes, peuvent décider d’instaurer ou non des mesures anténatales pour améliorer le pronostic des enfants à naître : corticothérapie, césarienne d’indication fœtale ou sulfate de magnésium à visée neuroprotectrice. Le rôle des équipes obstétricales pourrait ainsi être déterminant pour le pronostic des extrêmes prématurés et les raisons qui incitent les obstétriciens, en accord avec les parents, à initier ou non une prise en charge active anténatale sont mal connues. L’âge gestationnel est un facteur décisionnel bien connu sans qu’il n’y ait d’âge gestationnel seuil consensuel de prise en charge active en France. Mais il se pourrait aussi que les prises en charge varient selon les centres voire même selon les praticiens ou encore selon d’autres facteurs individuels liés aux femmes ou à leur grossesse. L’objectif de notre travail était dans un premier temps d’identifier, pour les naissances extrêmement prématurées en France, les déterminants individuels ou organisationnels associés à une prise en charge active anténatale. Dans certaines circonstances, volontaires ou non, les extrêmes prématurés naissent sans avoir bénéficié d’une prise en charge active anténatale. La plupart des nouveau-nés décèdent alors à la naissance mais certains d’entre eux sont néanmoins admis en réanimation néonatale. Le devenir de ces enfants, qui posent des difficultés médicales et éthiques, est mal connu. Étudier leur devenir néonatal était le deuxième objectif de ce travail. Les données de la cohorte EPIPAGE 2 ont été utilisées pour répondre à ces deux questions. Nous avons montré que les pratiques anténatales en cas de naissances extrêmes prématurées variaient de manière importante selon les régions avec des taux régionaux de prise en charge active anténatale allant de 22% (IC95% 0.05-0.38) à 61% (IC95% 0.44-0.78). Une prise en charge active anténatale était aussi plus fréquente pour les naissances à 25 et 26 SA que pour les naissances à 24 SA. Même après ajustement sur les caractéristiques individuelles et organisationnelles, les taux de prise en charge active variaient selon les établissements (p=0.03). Nous avons également souligné que les enfants admis en réanimation sans avoir pu bénéficier d’une prise en charge active anténatale ont un risque augmenté de morbi-mortalité néonatale par rapport aux enfants qui en ont bénéficié (Odds Ratio (OR) brut de 2.60, (IC95% 1.44-4.66 et OR ajusté de 1.86, (IC95% 1.09-3.20)). Les différences de pratiques anténatales entre les maternités de naissance, soulève la problématique de l’équité de la prise en charge ce d’autant que ces pratiques ont un impact sur le devenir immédiat de l’enfant. Ces résultats ont conduit certaines équipes françaises à réévaluer les processus de décisions autour de ces naissances afin d’harmoniser les pratiques. Au décours de ces réflexions, les sociétés savantes françaises proposent un guide d’aide à la décision pour la prise en charge des naissances extrêmes prématurées qui s’appuie sur une cohérence des soins prodigués avant, pendant et après la naissanceSurvival rates of extremely preterm neonates, infants born between 22 and 26 Weeks of Gestation (WG), are lower in France than in England, Sweden, the United States or Japan. This may be related to differences in the management of extreme preterm births and in particular to differences in antenatal practices. In the case of preterm births, obstetricians are the first to meet the mothers-to-be. They decide whether or not to implement antenatal measures to improve outcomes of these unborn children: corticosteroids, caesarean sections or magnesium sulphate for neuroprotective purposes. The provision of optimal antenatal care is key to the management and survival of extremely preterm births and obstetrical teams thus play a major role. Factors associated with active antenatal care have never been studied. The first objective of our work was to identify, for extreme preterm births in France, individual or organisational determinants associated with active antenatal care. Gestational age is a well-known decision-making factor, but care could also depend on individual factors related to women or their pregnancy, practitioners or maternity units. Some extremely preterm neonates are born without having received active antenatal care. For newborns who have not received such treatment, the risk of peripartum and delivery room death is high. However some extremely preterm neonates for whom active antenatal was either voluntarily withheld or not provided because of insufficient time are resuscitated and admitted to a Neonatal Intensive Care Unit (NICU). Neonatal outcomes for these children raise medical and ethical difficulties and are poorly known. Our second objective was to study neonatal outcomes of extremely preterm neonates admitted to NICU without prior active antenatal care. Data from the EPIPAGE 2 cohort were used to answer these questions. We have shown that antenatal management for extreme preterm births varies widely between regions with regional active antenatal care rates ranging from 22% (95% CI 0.05-0.38) to 61% (95% CI 0.44-0.78). Active antenatal care was more frequent for births occurring at 25 and 26 WG than for births occurring at 24 WG. Even after adjusting for individual and organisational characteristics, active antenatal care rates varied by maternity unit of birth (p = 0.03). We also underlined that children admitted to NICU without having received active antenatal care have an increased risk of neonatal morbidity and mortality compared to children who have (crude OR of 2.60, (95% CI 1.44-4.66), adjusted OR of 1.86, (95% CI 1.09-3.20)). Differences in antenatal management between maternity units raise the issue of equality of care, especially since these practices have an impact on neonatal outcomes. These findings have led French teams to reassess the decision-making process around extreme preterm births and to the elaboration of guidelines for the management of extreme preterm births