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Full and half sandwich compounds of dimolybdenum and ditungstenHollandsworth, Carl B. 12 October 2004 (has links)
No description available.
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Analýza vlivu fundamentálních zpráv na vývoj ceny zlata / Analysis and Influences of Fundamental news on Gold PricesKubaštová, Magdaléna January 2017 (has links)
This master thesis, Analysis and Influences of Fundamental news on Gold Prices deals with macroeconomic variables that drive the price of gold. This paper is divided into three chapters: Possible investment forms in gold, Fundamental analysis of commodities, and lastly Analysis of impact of strong economies and their influence on gold prices. In the first chapter, emphasis is put on the Efficient Market Theory that plays an important role in success or failure of investment strategies such as technical and fundamental analysis. The second chapter illustrates the Commitment of Traders (COT) report and how it is used as a tool to predict the movement of gold prices. This chapter also discusses other large drivers effecting gold prices such as financial and geopolitical stability, inflation, interest rates, Central Banking operations, the value of the US dollar, and other influences. The final chapter analyzes the impact of announced fundamental news in the United States, China, and Europe on the price of gold. The empirical part of this paper analysis the impact of announced fundamental news in United States, China and Europe on gold prices. With the use of the linear regression method, we can test whether the macroeconomic variables significantly influence the return on gold investments immediately after their announcement, or over long periods of time. If this new public data was calculated into gold prices directly, investors would not be able to achieve additional returns by using fundamental analysis. The major findings are summed up at the end of the last chapter.
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Dégradation des pesticides chlortoluron, carbofurane et bentazone en milieux aqueux par les procédés d'oxydation avancéeKesraoui-Abdessalem, Aida 12 December 2008 (has links) (PDF)
L'utilisation du procédé d'oxydation avancée électrochimique est un moyen simple et économique d'obtention des radicaux hydroxyles (OH*) fortement oxydants. Au cours de ce travail les radicaux ont été utilisés pour la dégradation du chlortoluron, du carbofurane et du bentazone en solution aqueuse. La méthodologie de la recherche expérimentale a été utilisée pour étudier l'influence de quelques paramètres (concentration du chlortoluron, l'intensité du courant et la durée du traitement, etc.) sur la vitesse de dégradation et pour déterminer les conditions optimale de minéralisation. L'évolution de la concentration des pesticides en fonction du temps de traitement montre une cinétique de pseudo-premier ordre (kabs = 4,92 × 109, 3.24 × 109 et 2.63 × 109 mol-1.L.s-1 respectivement pour le chlortoluron, le carbofurane et le bentazone). Dans nos conditions expérimentales optimales (I = 300 mA, [pesticide]0 = 0,125 × 10-3 mol.L-1 et t = 8 h), nous obtenons un taux de minéralisation supérieur à 90% pour les trois pesticides. Dans le cas des molécules étudiées, il a été montré que le taux de minéralisation par le procédé photo-Fenton (UV/Fe3+/H2O2) est fonction des doses des réactifs utilisés et de la concentration initiale des pesticides à traiter. Une comparaison des performances de minéralisation par les différents procédés étudiés (électro-Fenton (BDD), électro-Fenton (PT), oxydation anodique et photo-Fenton) a montré que les procédés photo-Fenton et électro-Fenton (BDD) permettent d'atteindre des taux de minéralisation très important (≈ 90% au bout de 2 h). La comparaison du coût du traitement montre que le procédé photo-Fenton coûte beaucoup plus chère que le procédé électro-Fenton (BDD). Le plasma d'air humide a été utilisé pour la dégradation du chlortoluron. Différents catalyseurs (Fe2+, Fe3+ et TiO2) ont été étudiés pour améliorer les performances du glidarc. La combinaison entre TiO2 et Fe2+ permet d'aboutir à 96%de la dégradation du chlortoluron au bout de 3 h.
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Cooperative versus Adversarial Learning: Generating Political TextJonsson, Jacob January 2018 (has links)
This thesis aims to evaluate the current state of the art for unconditional text generation and compare established models with novel approaches in the task of generating texts, after being trained on texts written by political parties from the Swedish Riksdag. First, the progression of language modeling from n-gram models and statistical models to neural network models is presented. This is followed by theoretical arguments for the development of adversarial training methods,where a generator neural network tries to fool a discriminator network, trained to distinguish between real and generated sentences. One of the methods in the research frontier diverges from the adversarial idea and instead uses cooperative training, where a mediator network is trained instead of a discriminator. The mediator is then used to estimate a symmetric divergence measure between the true distribution and the generator’s distribution, which is to be minimized in training. A set of experiments evaluates the performance of cooperative training and adversarial training, and finds that they both have advantages and disadvantages. In the experiments, the adversarial training increases the quality of generated texts, while the cooperative training increases the diversity. The findings are in line with the theoretical expectation. / Denna uppsats utvärderar några nyligen föreslagna metoder för obetingad textgenerering, baserade på s.k. “Generative Adversarial Networks” (GANs). Den jämför etablerade modeller med nya metoder för att generera text, efter att ha tränats på texter från de svenska Riksdagspartierna. Utvecklingen av språkmodellering från n-gram-modeller och statistiska modeller till modeller av neurala nätverk presenteras. Detta följs upp av teoretiska argument för utvecklingen av GANs, för vilka ett generatornätverk försöker överlista ett diskriminatornätverk, som tränas skilja mellan riktiga och genererade meningar. En av de senaste metoderna avviker från detta angreppssätt och introducerar istället kooperativ träning, där ett mediatornätverk tränas istället för en diskriminator. Mediatorn används sedan till att uppskatta ett symmetriskt divergensmått mellan den sanna distributionen och generatorns distribution, vilket träningen syftar till att minimera. En serie experiment utvärderar hur GANs och kooperativ träning presterar i förhållande till varandra, och finner att de båda har för- och nackdelar. I experimenten ökar GANs kvaliteten på texterna som genereras, medan kooperativ träning ökar mångfalden. Resultaten motsvarar vad som kan förväntas teoretiskt.
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Control and Modeling of High-Frequency Voltage Regulator Modules for Microprocessor ApplicationLi, Virginia 11 June 2021 (has links)
The future voltage regulator module (VRM) challenges of high bandwidth control with fast transient response, high current output, simple implementation, and efficient 48V solution are tackled in this dissertation. With the push for control bandwidth to meet design specifications for microprocessor VRM with larger and faster load transients, control can be saturated and lost for a significant period of time during transient. During this time, undesirable transient responses such as large undershoot and ringback occurs. Due to the loss of control, the existing tools to study the dynamic behavior of the system, such as small signal model, are insufficient to analyze the behavior of the system during this time. In order to have a better understanding of the system dynamic performance, the operation the VRM is analyzed in the state-plane for a clear visual understanding of the steady-state and transient behaviors.
Using the state-plane, a simplified state-plane trajectory control is proposed for constant on-time (COT) control to achieve the best transient possible for applications with adaptive voltage positioning (AVP). When the COT control is lost during a load step-up transient, the state-plane trajectory control will extend on-time to provide the a near optimal transient response. By observing the COT control law in the state-plane, a simplified state-plane trajectory control with analog implementation is proposed to achieve the best transient possible with smooth transitions in and out of the steady-state COT control. The concept of the simplified state-plane trajectory control is then extended to multiphase COT. For multiphase operation, additional operating behavior, such as phase overlapping during transient and interleaving during steady-state, need to be taken into consideration to design the desired state-plane trajectory control. A simple state-plane trajectory control with improved Ton extension is proposed and verified using multiphase COT control.
After tackling the state-plane trajectory control for current mode COT, the idea is then extended to V2 COT. V2 COT is a more advanced current mode control which requires a more advanced state-plane trajectory control to COT. By calculating the intersection of the extended on-stage trajectory during transient and the ideal off trajectory in the form of a current limiting wall, a near optimal transient response can be achieved. For V2 COT with state-plane trajectory control, implementations using inductor vs. capacitor current, effect of component tolerance, and effect of IC delay are studied. The proposed state-plane trajectory control is then extended to enhanced V2 COT.
Aside from tackling existing VRM challenges, the future datacenter 48V VRM challenge of a high efficiency, high power density solution to meet the VRM specifications is studied. The sigma converter is proposed for the 48V VRM solution due to exhibition of high efficiency and high-power density from hardware evaluation. An accurate model for the sigma converter is derived using the new modeling approach of modularizing the small signal components. Using the proposed model, the sigma converter is shown to naturally have very low output impedance, making the sigma converter suitable for microprocessor applications. The sigma converter is designed and optimized to achieve AVP and very fast transient response using both voltage-mode and current-mode controls. / Doctor of Philosophy / Microprocessors, such as central processing unit (CPU) and graphics processing unit (GPU) are the basis of today's electronics. In the recent decades, the demand for more powerful and faster data processing lead to a significant increase in power consumption by these microprocessors. Even with the introduction of multi-core processors and adaptive voltage positioning (AVP) to reduce the average power provided by the power supplies, the microprocessor can still draw a large amount of instantaneous power in a short period of time. With the microprocessors demanding high amount of current at fast slew-rate, the challenges for the next generation of microprocessor power supply, or voltage regulator modules (VRM), are fast response speed to ensure proper operation of the microprocessors, and high efficiency VRM to minimize the overall system power consumption.
The challenge of a VRM with fast response speed is tackled first. To meet the AVP and transient requirements of microprocessor, the VR need to utilize high-bandwidth control methods. Of the control methods used by the industry, high control bandwidth can be easily achieved using constant on-time (COT) control. With the ever-increasing output current level and transient slew-rate requirements, COT control can saturate and lose its steady-state control for a period of time during load step-up transient. During this time, the system will operate with a fixed frequency control until COT control is recovered. Although the method is widely used in the industry, the method is too slow to meet the transient requirements. Many state-of-art methods have been proposed to resolve the load step-up transient issue of COT. However, of the methods proposed, it is difficult to optimize the transient improvement while having a simple analog implementation to ensure a fast response for the wide operating range and aggressive transient conditions observed in microprocessor VRM application.
In this dissertation, COT control is studied using the state-plane to provide a clear visual understanding of the transient behavior of the control. Using the state-plane, a state-plane trajectory control is proposed to achieve near optimal load step-up transient response. The concept is then extended to multiphase VRM, which is typically used for high current applications. The state-plane trajectory control concept is then further extended to V2 COT control for VRM without AVP, such as those used by GPU and smartphone CPU. For the proposed state-plane trajectory controls, hardware implementation, evaluation, and experimental results are provided.
After tackling the challenge of a VRM with fast response speed, the challenge of an efficient VRM is then tackled. In recent years, a significant amount of research has been put into studying VRM for a power delivery architecture which uses a 48V bus instead of the 12V bus. By using the 48V bus, less redundancy in the power delivery path can greatly increase the overall system efficiency if the VRM stage retains its efficiency. However, the increase in input voltage for the VRM provides an additional challenge to maintain high efficiency for the VRM stage itself. To maintain good efficiency, it is difficult to increase converter switching frequency beyond 300kHz. This limitation on switching frequency will limit the ability to achieve high bandwidth design and fast transient requirements.
A 48V VRM using a different topology, the sigma converter, has demonstrated high-efficiency and high-power density, but the converter behavior and control methodology for VRM application is unclear. In this dissertation, the modeling and control of the sigma converter are studied using the proposed small-signal model. By evaluating the proposed small-signal model, the sigma converter can naturally have very low output impedance, making it an ideal candidate for 48V VRM. Then, the design guideline of the sigma converter with current-mode control is provided. With the work discussed in this dissertation, further study of the sigma converter with COT and state-plane trajectory control can be conducted in the future.
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A Constant ON-Time 3-Level Buck Converter for Low Power ApplicationsCassidy, Brian Michael 22 April 2015 (has links)
Smart cameras operate mostly in sleep mode, which is light load for power supplies. Typical buck converter applications have low efficiency under the light load condition, primarily from their power stage and control being optimized for heavy load. The battery life of a smart camera can be extended through improvement of the light load efficiency of the buck converter. This thesis research investigated the first stage converter of a car black box to provide power to a microprocessor, camera, and several other peripherals. The input voltage of the converter is 12 V, and the output voltage is 5 V with the load range being 20 mA (100 mW) to 1000 mA (5000 mW). The primary design objective of the converter is to improve light load efficiency.
A 3-level buck converter and its control scheme proposed by Reusch were adopted for the converter in this thesis. A 3-level buck converter has two more MOSFETs and one more capacitor than a synchronous buck converter. Q1 and Q2 are considered the top MOSFETs, while Q3 and Q4 are the synchronous ones. The extra capacitor is used as a second power source to supply the load, which is connected between the source of Q1 and the drain of Q2 and the source of Q3 and the drain of Q4. The methods considered to improve light load efficiency are: PFM (pulse frequency modulation) control scheme with DCM (discontinuous conduction mode) and use of Schottky diodes in lieu of the synchronous MOSFETs, Q3 and Q4. The 3-level buck converter operates in CCM for heavy load above 330 mA and DCM for light load below 330 mA. The first method uses a COT (constant on-time) valley current mode controller that has a built in inductor current zero-crossing detector. COT is used to implement PFM, while the zero-crossing detector allows for DCM. The increase in efficiency comes from reducing the switching frequency as the load decreases by minimizing switching and gate driving loss. The second method uses an external current sense amplifier and a comparator to detect when to shut down the gate drivers for Q3 and Q4. Schottky diodes in parallel with Q3 and Q4 carry the load current when the MOSFETs are off. This increases the efficiency through a reduction in switching loss, gate driving loss, and gate driver power consumption.
The proposed converter is prototyped using discrete components. LTC3833 is used as the COT valley current mode controller, which is the center of the control scheme. The efficiency of the 3-level buck converter was measured and ranges from 82% to 95% at 100 mW and 5000 mW, respectively. The transient response of the converter shows no overshoot due to a 500 mA load step up or down, and the output voltage ripple is 30 mV. The majority of the loss comes from the external components, which include a D FF (D flip-flop), AND gate, OR gate, current sense chip, comparator, and four gate drivers. The proposed converter was compared to two off-the-shelf synchronous buck converters. The proposed converter has good efficiency and performance when compared to the other converters, despite the fact that the converter is realized using discrete components. / Master of Science
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Časopisy cestovního ruchu na českém mediálním trhu - komparativní analýza titulů COT business a National Geographic / Travel tourism magazines on the czech media market-a comparative analysis of the C.O.T.Business and National geographicJuránková, Simona January 2013 (has links)
Travel periodicals are one of the means, how can readers - potential tourists to learn about a specific destination, or be motivated to visit presented country. This diploma thesis describes the development and transformation of the tourism magazines that are published in the Czech Republic after 1989. The attention is focused on the title COT business (for professionals) and National Geographic (for the public). Although targeted at different audiences, both periodicals bring news and coverage from destinations, interviews with travelers, practical travel advices and thus contribute for the increase or decline of demand for various places. Selected magazines gradually gained a strong position on the Czech media market and can be thus described as prototypes in their segment. Especially in recent years in comparison with the competition selected periodicals have declined in sold costs, advertising revenues and readership. The aim of this thesis is to investigate the market overall with selected travel periodicals and also identify opportunities that should selected titles (publishers) include into marketing planning, if they want to stay "leaders" on the media market. The thesis also presents a case study that is comparing the framing methods of selected destinations in order to determine, to what...
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Analyse du bilan de matière du pétrole dans une région en phase d'exploitation avancée - bassin de Reconcavo, BrésilCarvalho Coutinho, Luiz Felipe 10 July 2008 (has links) (PDF)
Etablir un bilan de masses entre la génération, la migration et l'accumulation du pétrole est un processus important pour quantifier des systèmes pétroliers. Ce bilan donne en effet des indications sur la répartition du pètrole dans un bassin sédimentaire, que ce soit une province très explorée ou un secteur d'exploration frontière. Cette thèse a établi la méthodologie pour approcher un bilan de masses d'un système pétrolier sur un cas réel. Elle a non seulement quantifié les termes sources et les pertes, mais s'est également intéressée aux aspects compositionnels. Les accumulations connues ont pour cela servi de données de calibration des paramètres influant le bilan. Dans cette optique, le cas d'étude choisi est le bassin de Recôncavo au Nord-Est du Brésil. Il s'agit d'un rift avorté qui a été formé pendant la fragmentation du Gondwana, au cours de le Crétacé Inférieur. Le stade mature de l'exploration de ce bassin a contribué à réduire les incertitudes sur les pertes et les charges, points essentiels d'une définition de bilan de matière. Les nombreux paramètres qui influencent le bilan ont pu être calibrés de façon précise. Pour procéder au bilan, on a d'abord effectué des analyses géochimiques pour la description cinétique compositionnelle des membres Tauá et Gomo (Fm. Candeias), les roches mères principales de ce bassin. Une loi de restauration du carbone organique total (COT) a été obtenue en résultat des expériences thermogravimétriques et de l'analyse Rock-Eval. Une deuxième partie de ce travail a intégré les résultats de géochimie dans un schéma séquentiel de modélisation de systèmes pétroliers en 1D,2D et 3D. Une calibration du régime thermique au cours du temps géologique indépendante des données de maturité a servi de guide pour le terme source. Puis la genèse, l'expulsion et la migration ont été modélisées. Ces résultats ont fourni les éléments du bilan de masses sur ce bassin, qui montre que seulement 8% des hydrocarbures expulsés des roches-mères ont été piégés, 16% sont perdus dans le réseau poreux non réservoir et 76% sont sortis du système latéralement ou par exsudation au cours de son évolution.
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Sudden Unexpected Death in Infants (SUDI) and parental infant care: perspectives of general practitioners, nurses and parents living and working in the multicultural community of Western SydneyWilson, Leigh Ann January 2009 (has links)
Doctor of Public Health / For many years the major cause of infant mortality in NSW has been the result of Sudden Infant Death Syndrome (SIDS). Statistics show the area defined as 'Western Sydney' is no exception, and in 2002, a report prepared by the Epidemiology, Indicators, Evaluation and Research Unit (EIRE) in Western Sydney presented data indicating SIDS rates in the area were higher than the state average. In particular, two Local Government Areas (LGAs) had clusters of SIDS deaths. Previous Australian research identified a higher risk of SIDS and other causes of infant mortality in Aboriginal and Torres Strait Islander populations. The areas of Western Sydney where SIDS rates were higher than expected were home to Aboriginal, Torres Strait Islander and Pacific Island residents. The number of SIDS deaths in Aboriginal infants did not explain the higher than expected rate of SIDS in the areas under investigation. Studies undertaken in New Zealand and the Pacific Islands have identified higher than expected risk of SIDS in Maori and Pacific Island communities in those countries, although this has never been studied in Pacific Island residents living in Australia. The reasons for these communities exhibiting a higher than normal SIDS rate is not completely understood, but can be partially explained by behavioural practices which are known to impact adversely on the risk of SIDS. This study sought to investigate the level of knowledge concerning the prevention of sudden and unexpected death in infants (SUDI) in three key groups of infant caregivers: general practitioners, nurses and parents living or working in the area geographically defined by Sydney West Area Health Service (WSAHS). In addition, the study sought to identify any variation in knowledge of SIDS reduction strategies in the three groups under study, and to investigate factors influencing knowledge and practice in these participants. The study findings were then used as a basis on which to develop strategies and recommendations to enhance the delivery of safe sleeping messages through the health care system. Using a combination of qualitative and quantitative methods, this cross-sectional study highlights a number of issues around infant care practices and the major influences on new parents living in a multicultural community. Results of the study showed there is a large variation in knowledge around safe sleeping practices (including SIDS reduction strategies) in all the groups studied. Although educational campaigns are conducted regularly, many general practitioners and parents are confused about the key SIDS reduction messages and still place infants in sleeping positions considered unsafe. While nurses and midwives were aware of the SIDS reduction strategies, they still occasionally used infant sleeping positions considered unsafe. General practitioners born overseas in a country where English is not the first language were less likely to be familiar with safe sleeping messages, including SIDS reduction strategies. Families from a Culturally and Linguistically Diverse (CALD) background were less likely to have seen SIDS information in their own language than families who spoke English, and as a result were more likely to use traditional methods of infant care, including co-sleeping with siblings and parents and side or tummy sleeping. CALD parents were more likely to rely on herbal remedies and friends and family for assistance, than English speaking parents who accessed health professionals as the first point of call when infants were unwell. The study identified a relatively recent practice, which until reported in this study, has not been documented in the literature. The practice of draping infant prams with blankets originated from the Cancer Council of Australia guidelines which recommend covering a pram with a light muslin wrap to protect infants’ skin from the sun. It appears parents have misinterpreted this message and are covering infant prams with blankets to encourage sleep, even when sun exposure is not an issue. Research suggests that poor air quality around the head of an infant may affect an infant’s arousal response. While no research has been conducted on the air quality around an infants head when covered by a heavy blanket in a pram, it is possible based on research into air quality around infants, that that this practice may increase the risk of sudden and unexpected death in an infant. In conclusion, this study found that multiple changes to the SIDS reduction messages since the initial ‘Reduce the Risks’ Campaign have led to confusion about ways of preventing SIDS in GPs, nurses and parents in Western Sydney. The study makes seven recommendations aimed at improving knowledge of safe sleeping practices in these groups, and optimizing health outcomes for infants using a collaborative approach to service delivery and future initiatives.
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A systematic literature review on cloud of things vulnerabilityPirahandeh, Mehdi January 2018 (has links)
Every day, a new publication on information systems highlights about Cloud of Things (CoT) vulnerabilities; in most of these publications, vulnerability is quoted as the most substantial barrier for CoT realization. However, formulating a justifiable appraisement of the actual vulnerability impact on CoT is difficult because in many of these publications, the term security “vulnerability” is stated incorrectly as a threat or the publication does not discuss CoT-specific vulnerabilities. To achieve a well-founded understanding of CoT vulnerabilities, this literature review identifies the major vulnerabilities and their security controls and to identify any gaps for future research. A systematic literature review (SLR) approach using 58 articles is considered for this review. Based on this review, a taxonomy is created to classify the existing CoT vulnerabilities and security controls. This literature review identifies and discusses similarities and differences among various vulnerability issues and solutions. Most reviews previously performed were limited to the threats to the application interface and virtualization level, whereas this SLR thesis expand to the vulnerabilities in connectivity and things level of CoT. This study emphasize the importance of a clear definition of cloud of things vulnerabilities and to facilitate better understanding and assessment of CoT vulnerabilities to build more secure systems.
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