Le déploiement à grande échelle de l’internet des objets nécessite le développement de systèmes de radiocommunication plus économes en énergie, dont le circuit de génération de fréquences est connu pour être particulièrement énergivore. L’objectif de ce travail de thèse est donc d’une part de développer une synthèse de fréquences très faible consommation et d’autre part de démontrer les performances de la technologie FDSOI pour des applications analogiques et radiofréquences. Dans le premier chapitre sont présentées les spécifications du standard choisi -le BLE-, les spécificités de la technologie FDSOI et l'état de l’art des architectures de transmetteurs radiofréquences à faible consommation. Nous avons retenue de cette comparaison l'architecture à division par phases. Le deuxième chapitre présente les résultats de trois types de modélisation système de l’architecture ; 1 - le fonctionnement de ses composants et les points clés à respecter pour son implémentation, 2 - le comportement en bruit de phase pour la définition des spécifications, et 3 - l’impact de l’architecture sur la génération de raies spectrales parasites. Cette étude nous a permis de fixer le cahier des charges du VCRO développé au chapitre suivant. Le troisième chapitre est consacré à la conception, la réalisation et le test de 4 topologies de VCROs en technologie FDSOI 28nm et d'un circuit de test. Les premiers résultats de mesure sont encourageants mais nécessitent d’être complétés par des mesures avec PLL fractionnaire intégrée. En effet, la sensibilité des circuits à la tension d’alimentation (pushing de l’ordre de 5 GHz/V) a rendu les mesures du bruit de phase très délicates. / The large-scale deployment of IoT requires the development of more efficient energy radio systems, within which the frequency generation circuit is known to be particularly energy-consuming. The objective of this thesis is firstly to develop a very low consumption frequency synthesis and secondly to demonstrate the performance of the FDSOI technology for analog and RF applications.In the first chapter are the specifications of the chosen standard -the BLE-, the specifications of the FDSOI technology and state of the art of low power radio frequency synthesizers architecture. We have chosen from this comparison the Fractional Phase Divider architecture. The second chapter presents the results of three types of system simulations of the PLL; 1 - the operation of its components and the key points to be respected for its implementation, 2 - the phase noise behavior for the definition of specifications, and 3 - the impact of architecture on the generation of spurious. This study allowed us to set the specifications of VCROs developed in the next chapter. The third chapter is dedicated to the design, implementation and testing of four topologies of VCROs and a test circuit in FDSOI 28nm technology. The first measurement results are encouraging but they need to be complemented by an integrated fractional PLL measurement. Indeed, the sensitivity of the circuits to the supply voltage (pushing of about 5 GHz/V) made measurements of phase noise very delicate. The measured consumption is less than 0.8 mA and the surface of the circuits is of the order of 600 µm².In the fourth and final chapter we present the implementation at circuit-level of a phase synchronization PLL.

Uma das dificuldades do processo de retificação center-less é o estabelecimento de padrões confiáveis que determine com pequena margem de erro problemas no processo. Este trabalho visa desenvolver um sistema de monitoramento capaz de identificar falhas ocorridas durante a dressagem e o processo de retificação center-less acima dos centros de hastes de válvulas. Para tanto, inicialmente, foi feito um estudo teórico e prático acerca do processo de retificação center-less com o objetivo de conhecer seus elementos básicos, características, principais problemas e fatores que influenciam o processo. Em função da grande aplicação da emissão acústica em operações de retificação, foi desenvolvida uma nova metodologia, onde foi possível criar um mapa digital, baseado em informações acústicas detalhadas do processo, usando para isto uma constante de tempo muito pequena. Os resultados mostraram a potencialidade do sistema de mapeamento em detectar e diagnosticar problemas ocorridos durante processos de retificação e dressagem. Assim, pode-se atuar sobre o processo de tal forma a corrigir estas anomalias. / One of the difficulties of the center-less grinding process is to establish reliable patterns to determine, with a small error, problems in the process. This work aims to develop an monitoring system able to identify flaws happening during the dressing and the center-less grinding process above the center of values stems. Initially a theoretical and practical study was conduct on the center-less grinding process with the objective of discussing its basic elements, characteristics, main problems and factors that influence the process. Due to the great application of acoustic emission in grinding operations a new methodology was developed, where it was possible to create a digital map, based on detailed acoustic information on the process using for this a very short time constant. The results showed the potentiality of this mapping system to detect and to diagnose problems during grinding and dressing. Therefore, it is possible to correct anomalies when plunge center-less grinding process.

This study explores protean and boundaryless career attitudes in a sample of black British knowledge intensive workers. Changes in the organisational climate to more flexible project based working have affected the way in which careers develop. It has been reported that employees need to possess certain skills to help them succeed in the modern employment climate (Arthur and Rousseau 1996). The main research theory that has attempted to explain such career changes and the acquisition of specialist skills include the boundaryless career which includes both intelligent and protean career competencies (Greenhaus et al 2004). The purpose of the current study is to investigate the extent to which black African and black Caribbean workers careers are boundaryless and to investigate the nature and type of career boundaries and barriers faced. The current research addresses some of the criticisms of boundaryless career research highlighted by Sullivan et al (1998, 1999, 2009). These criticisms include an apparent exaggeration of the pervasiveness of boundaryless and protean careers and a lack of research investigating the applicability of these career theories to professional, minority group members. Thirty two knowledge workers were interviewed to understand the nature and type of career boundaries faced. A quantitative questionnaire developed by Briscoe et al (2006) was also used to investigate the extent to which black knowledge workers are protean and boundaryless in their career outlook. The findings from the interviews highlight education and family as career enablers as they help participants navigate potential career barriers. The lack of career mentors, racial discrimination and inadequate career advice at an early age were perceived as career boundaries. Results also point to a perceptual difference between career boundaries and barriers which researchers such as Sullivan et al (2004) saught to clarify. The findings suggest that career boundaries are more flexible and less permeable and career barriers are more rigid and difficult to overcome. Briscoe et al (2006) boundaryless and protean scales and were completed by 187 participants. It was found that management consultants, those aged 41-50 and those with higher levels of education were found to be the most boundaryless. The main theoretical contribution is that “attached boundaryless” is displayed. Attached boundarylessness occurred as participants preferred the security of remaining in an organisation, but enjoyed being self directed and boundaryless within their organisations by working collaboratively.

Contact-less transfer of energy has always been a desired feature for systems that require reliable and durable power transfer across their moving parts. In rotary equipment in particular, slip-rings are the established solution with off-the-shelf and customised solutions readily available in the market. Despite the mature technology, slip-rings suffer wear and are prone to arcing, making frequent maintenance a necessity. In this project a rotating transformer is proposed as an alternative solution for contact-less transfer of energy across the revolving frame of an airborne electronic-scanning radar. This thesis is based on the hypothesis that the Phase-Shifted Full Bridge (PSFB) topology can efectively utilise the parasitic components of the rotating transformer to achieve efficient (over 90%) power conversion at the kW range. The first part of this work concentrates on the study of the magnetic interface and its electrical properties. Initially the magnetic structure of the transformer is studied in order to gain understanding of the effects of the physical layout of the component to its electrical behaviour. The problems of low magnetising and increased leakage inductance are quantified by measurements, calculations and finite element analysis. An accurate electrical model is built and used to calculate the transformer voltage and current gain. The second part of the research programme aims at the compilation of a design strategy for a PSFB incorporating a rotating transformer. An algorithm is presented, that optimises the magnetic component structure in order to achieve minimum switching losses and spread the conduction losses between the transformer and power switches. The last stage involves the evaluation of the design algorithm through prototyping and testing. Some topological variations are tested and compared with the original conventional PSFB converter. The thesis concludes with a discussion of the results and future challenges.

Diante da previsão de escassez de água no mundo, torna-se necessário desenvolver tecnologias que permitem o reaproveitamento de águas salinas.A hidroponia é uma técnica de cultivo sem solo que permite obter produtos de alta qualidade, maior produção por área, menor gasto de água e insumos agrícolas, contribuindo com a preservação dos recursos naturais e do ambiente. A alface (Lactuca sativa) é a hortaliça mais importante produzida no sistema hidropônico (NFT). O uso de água salina na produção de hortaliças constitui no momento atividade essencial, tendo em vista o aumento da demanda de água doce, tanto pela atividade agrícola quanto pelo abastecimento urbano e industrial. Dessa forma os objetivos do trabalho são: i) avaliar o crescimento, a produção e qualidade de duas variedades cultivadas de alface (Verônica e Pira Roxa) em sistema hidropônico NFT (Fluxo Laminar de Nutrientes) com a utilização de águas salinas no preparo da solução nutritiva e na reposição da lâmina diária evapotranspirada ao longo do ciclo de cultivo; ii) avaliar a qualidade, os parâmetros fisiológicos e bioquímicos (teor de nitrato, clorofila e prolina). Os experimentos foram conduzidos em ambiente protegido localizado na área experimental do Setor de Irrigação e Drenagem do Departamento de Engenharia Rural da Escola Superior de Agricultura Luiz de Queiroz - ESALQ/USP, no município de Piracicaba-SP. O delineamento experimental foi blocos ao acaso. Avaliaram-se cinco níveis de salinidade obtidos com a adição de NaCl, que resultaram em diferentes condutividades elétricas da água: 0,42, 1,53, 3,52, 5,55 e 7,43 (dS.m-1) e duas variedades cultivadas de alface Verônica e Pira Roxa. Os resultados revelaram que a salinidade da água reduziu o crescimento e a produção de forma linear decrescente. A tolerância à salinidade de alface variedade cultivada Verônica foi superior em relação à variedade cultivada Pira Roxa. A salinidade alterou o teor de nitrato, prolina e clorofila, sendo o efeito superior na cv. Pira Roxa, denotando ser um mecanismo de defesa à salinidade. Com relação à produtividade comercial, obteve-se uma perda de 69% e 64% para as variedades cultivadas Pira Roxa e Verônica, respectivamente, quando se utilizou água mais salina (7,43 dS.m-1). Os resultados obtidos em sistema de cultivo NFT podem indicar a possibilidade do uso da água salina como alternativa para produção de hortaliças para produtores que tem disponibilidade de água salina e restrita disponibilidade de água doce. / Before the forescast of shortage of water in the world, becomes necessary to develop technologies that allow the reuse of saline waters. The NFT (Nutrient Film Technique) is a cultivation technique soil less that allows to obtain products of high quality, larger production for area, minor expense of water and agricultural inputs, contributing with the preservation of the natural resources and environment. A lettuce (Lactuca sativa) is the most important vegetable produced in the hydroponic system (NFT). The use of saline water in the production of vegetables constitutes in the moment essential activity, tends in view the increase of the demand of fresh water, so much for the agricultural activity as for the urban and industrial supplying. The objectives of the work were: i) to evaluate the growth, the production and quality of two cultivates of lettuce (Verônica and Pira Roxa) cultivated in hydroponic system NFT (Nutrient Film Technique) with the use of saline waters in the preparation of the nutrient solution and replacement of the evapotranspiration along the cultivation cycle; ii) to evaluate quality, the physiologic and biochemical parameters (nitrate, chlorophyll and prolina content). The experiments were carried out in atmosphere protected on the experimental area of the Irrigation and Drainage Section of the University of São Paulo (ESALQ/USP), Piracicaba, State of São Paulo, Brazil. The experimental design used was randomized blocks. It were evaluated five salinity levels obtained with the addition of NaCl that resulted in different electrical conductivities of the water (0.42, 1.53, 3.52, 5.55 and 7.43 dS.m-1); and two cultivated variety of lettuce Verônica and Pira Roxa. The results revealed that the salinity of the water reduced the growth and production in a decreasing lineal. The tolerance to salinity of the lettuce cultivated variety Verônica was superior in relation cultivated variety Pira Roxa. The salinity altered the contents of nitrate, prolina and chlorophyll, being the superior effect in the cv. Pira Roxa, denoting to be a defense mechanism the salinity. The commercial productivity was obtained a loss of 69% and 64% for cultivated variety Pira Roxa and Verônica, respectively, when more saline water was used (7,43 dS.m-1). The results obtained in cultivation system NFT they can indicate the possibility of the use of the saline water as alternative for production of vegetables for producers that has availability of saline water and restricted of fresh water.

The question that Less Developed Countries have faced since the advent of floating exchange rates among the Industrial Countries is whether they should also adopt a floating exchange rate system. The Less Developed Countries have opted for a pegged exchange rate system, since their economic characteristics and institutional structure indicate that floating for the Less Developed Countries would result in volatile or unstable exchange rates. Since Less Developed Countries peg t heir exchange rates in the presence of flexible rates among industrial countries, the Less Developed Countries pegged exchange rates move in accordance to the exchange rates to which they are pegged. This study examines whether there are differences in the variability of the different effective exchange rate indices or currency baskets. Specifically the export, import and total trade weighted effective exchange rates for three African Less Developed Countries are examined. Currency baskets are varied by changing the number of currencies coefficent of variation included in was used the basket. The to compare the variability in the different effective exchange rates.

A well-exposed suite of Colorado River fill terraces preserved at Lees Ferry records the oscillating history of this major river superimposed on its overall downcutting of the Colorado Plateau. Detailed mapping, sedimentology, cross-sectional surveys, and the use of two geochronometers have been used in order to establish a detailed chronostratigraphy for the area. Eight distinct deposits have been identified along the Colorado River (Ml -M7, and S3), and four deposits have been identified along the Paria River (Pl -P4). Geochronology of six of these deposits using optically stimulated luminescence and cosmogenic 10Be exposure techniques indicates a long-term average bedrock incision rate of 290 to 470 m/my. These incision rates are approximately two to three times higher than others reported in Grand Canyon and the upper Colorado River basin, but are similar to the recently reported high incision rates near Glen Canyon and along the Fremont River. These results suggest that there is a region of faster incision along the Colorado River in the central Colorado Plateau in the vicinity of Lees Ferry and Glen Canyon. This apparent increase in central plateau Pleistocene incision rates may be caused by either epeirogenic uplift due to tectonics and erosional isostatic rebound, or transient waves of incision in response to original drainage integration. In addition to recording the incision history of the Colorado River, the well-preserved Pleistocene fluvial terraces provide evidence regarding the timing and processes of terrace formation at Lees Ferry. Chronostratigraphic analysis indicates that aggradation was occurring at - 20 ka (M2), - 70 to 40 ka (M3), - 115 to 90 ka (M4), and - 130 ka (MS). Aggradation and incision along the Paria River appears to be occurring at the same time as that on the Colorado River. Deposits at Lees Ferry are generally younger than correlative deposits in headwater catchments and in eastern Grand Canyon. ln addition, the most prominent deposit in the Lees Ferry area (M4) correlates to MIS stage 5b-c, a time in which no glaciations have been reported in headwater drainages. Data from this study indicate that fluvial responses at Lees Ferry are a complicated integration of signals from climate change in headwater catchments and sediment production from local hillslopes and tributaries.

Three-Phase Voltage Source Converters (VSCs) are finding widespread applications in grid integrated power conversion systems. The control systems of such VSCs are in an increasing number of these applications required to operate during voltage disturbances and unbalanced conditions. Control systems designed for grid side voltagesensor- less operation are at the same time becoming attractive due to the continuous drive for cost reduction and increased reliability of VSCs, but are not commonly applied for operation during unbalanced conditions. Methods for voltage-sensor-less grid synchronization and control of VSCs under unbalanced grid voltage conditions will therefore be the main focus of this Thesis. Estimation methods based on the concept of Virtual Flux, considering the integral of the converter voltage in analogy to the flux of an electric machine, are among the simplest and most well known techniques for achieving voltage-sensor-less grid synchronization. Most of the established techniques for Virtual Flux estimation are, however, either sensitive to grid frequency variations or they are not easily adaptable for operation under unbalanced grid voltage conditions. This Thesis addresses both these issues by proposing a simple approach for Virtual Flux estimation by utilizing a frequency-adaptive filter based on a Second Order Generalized Integrator (SOGI). The proposed approach can be used to achieve on-line frequency-adaptive varieties of conventional strategies for Virtual Flux estimation. The main advantage is, however, that the SOGI-based Virtual Flux estimation can be arranged in a structure that achieves inherent symmetrical component sequence separation under unbalanced conditions. The proposed method for Virtual Flux estimation can be used as a general basis for voltage-sensor-less grid synchronization and control during unbalanced conditions. In this Thesis, the estimated Virtual Flux signals are used to develop a flexible strategy for control of active and reactive power flow, formulated as generalized equations for current reference calculation. A simple, but general, implementation is therefore achieved, where the control objective and the power flow characteristics can be selected according to the requirements of any particular application. Thus, the same control structure can be used to achieve for instance balanced sinusoidal currents or elimination of double frequency active power oscillations during unbalanced conditions. In case of voltage sags, current references corresponding to a specified active or reactive power flow might exceed the current capability of the converter. The limits for active and reactive power transfer during unbalanced conditions have therefore been analyzed, and generalized strategies for current reference calculation when operating under current limitations have been derived. The specified objectives for active and reactive power flow characteristics can therefore be maintained during unbalanced grid conditions, while the average active and reactive power flow is limited to keep the current references within safe values. All concepts and techniques proposed in this Thesis have been verified by simulations and laboratory experiments. The SOGI-based method for Virtual Flux estimation and the strategies for active and reactive power control with current limitation can also be easily adapted for a wide range of applications and can be combined with various types of inner loop control structures. Therefore, the proposed approach can potentially be used as a general basis for Virtual Flux-based voltage-sensor-less operation of VSCs under unbalanced grid voltage conditions.

A cloned esterase and several cytoplasmic proteins which lack a classical cleavable signal-peptide were secreted during late stationary phase in B. subtilis. Several lines of evidence indicate that secretion of enolase, SodA, and Est55 is not due to cell lysis. The extent of possible release of these proteins mediated by membrane vesicles into the medium was also found to be minimal. We have identified a hydrophobic α–helical domain within enolase that contributes to the secretion specificity. Thus, upon the genetic deletion or replacement of a potential membrane-embedding domain, the secretion of plasmid-encoded mutant enolases is totally blocked, while that of the wild-type chromosomal enolase is not affected in the same cultures. However, mutations on the conserved basic residues flanking the hydrophobic core region show no effect. GFP fusion experiments demonstrate that minimal length of N-terminus 140 amino acids and its tertiary structure are required to serve as a functional signal for the export of enolase. Transcriptome analysis revealed several interesting patterns in gene expression when the cell growth switches from exponential phase into stationary phase. As expected, once cell growth enters the stationary phase, expressions of most SigA-dependent house-keeping genes (for syntheses of ATP, amino acids, nucleotides, ribosomes), and surprisingly secY and yidC homolog in the Sec-dependent general protein secretion system were significantly decreased; however, secA and sipT were found progressively induced in the stationary phase. The sigB gene and the SigB regulon exhibited a distinct pattern of transient induction with a peak in transition phase. A total of 62 genes were induced by three fold after cessation of SigB-dependent surge, which includes sigW and many of SigW-depedent genes specifically for antitoxin resistant genes, and some unknown function genes. In addition, oxidative stress response and damage repair genes also dominantly induced in stationary phase implied a high level of oxidant or thio-depleting agents in stationary phase. Besides, induction of fruRAB at T40 and gap operon at T100 suggested a sequential switch of carbon utilization from glucose to fructose. These results indicate a complex adaptation physiology as Bacillus cells change from the fast growing exponential phase toward the stationary phase.

No description available.