This diploma thesis deals with the design of pneumatic pressure switch with adjustable hysteresis. In the thesis is carried out the introduction in the theory of compressed air and research of the pressure switches at the market. Based on the gathered information and customer specification, the design draft of the pressure switch has been created. In the thesis are described three main parts of the prototype: transform of the pressure, adjustable hysteresis and synchronization of the microswitches. In the end of the thesis is described the testing of prototype and summary of the results.

Portfolio strategies focusing on following the trend, so called momentum based strategies, have been popular for a long time among investors and have had many academic studies, however with varying results. This study sets out to investigate different momentum trading signals as well as combining them in ensemble models such as Random Forest and the unique Dim Switch portfolio and then compare them to set benchmarks. Only one of the benchmarks, the 100% equity portfolio, is found to have better returns than the constructed momentum based strategies, however the momentum based strategies show a lot of potential with high risk-adjusted returns and good performance with regards to Expected Shortfall, Value at Risk and Maximum Drawdown. The most common momentum trading signal, the momentum rule with 9 months lookback, was found to have the highest risk-adjusted returns compared to both the benchmarks and the ensemble models, but it was also found to have slightly heavier left tail than the ensemble models. / Portföljstrategier som baserar sig på att följa trenden, så kallade momentumstrategier, har varit populära länge bland investerare. Många akademiska studier har gjorts om ämnet med varierande resultat. Denna studie utreder olika trendsignaler och kombinerar dem för att forma så kallade ensemble modeller, mer specifikt Random Forest och den unika "Dim Switch"-approachen, för att sedan jämföra dessa strategier mot benchmark portföljer. Endast en av benchmark portföljerna, 100% aktier i en ''buy and hold''-portfölj hade bättre avkastning än de momentumbaserade ensemble modellerna i studien. Däremot har momentumbaserade ensemble modellerna högre riskjusterad avkastning, Expected Shortfall, Value at Risk och Maximum drawdown. Den mest återkommande trendsignalen ''Momentum rule'' med nio månaders lookback hade extremt hög riskjusterad avkastning jämfört med benchmarks och ensemble modellerna, men det kom med kostnaden av högre risker i svansen.

Electrical switches are ubiquitous. Performance requirement for a switch is stringent. The operating mechanism mostly decides the performance of an electromechanical switch. However, design of such mechanisms, which involve discontinuous motions, is not much addressed in literature. The present work proposes a systematic procedure to design and analyze toggle based switching mechanisms. The work defined the toggle phenomenon rigorously, and, based on the behaviour of the toggles, provided a classification scheme for the switch mechanisms. The existing switches fall in two major categories viz., single-toggle and double-toggle switches. The double toggle mechanism is more suitable for high power breaking as it can isolate the system’s behaviour from the operator’s behaviour. The kinematic and geometric attributes of the operating mechanism which affect the toggle sequence and timings have been identified. A systematic simulation based study has been performed to identify the influence of different kinematic and dynamic parameters on the functionality of a double toggle switching mechanism. The influence of the variable moment of inertia and mechanism singularities arising out of introduction of the four bar sub chain on the performance of the system have been studied in detail. It is observed that the performance of the double toggle systems is less susceptible, though not immune to the user behaviour; in extreme scenarios the switching performance could become erratic. The use of an additional spring in an existing system enhanced the system performance; but, connecting the main spring with the coupler link altered the system performance more dramatically. Thus it established that the influence of the kinematic configuration on the performance of a switching mechanism is more pronounced than the dynamic characteristics of a comparable system. For the ab initio design of double toggle switching mechanisms, necessary structural criteria for a mechanism to exhibit double toggle phenomenon have been identified and verified with various 2 d.o.f. systems. It is also established that any double toggle mechanism cannot be used directly as a switching mechanism; the link dimensions, link arrangements and the stopper locations have to be chosen properly. Towards that end, three necessary kinematic criteria for a switching mechanism are identified. A few mechanisms which satisfy all structural and kinematic criteria are identified; the switching and toggle behaviour of these mechanisms are examined through simulations using Pro/Mechanism. Finally, considering all the conditions a is constructed with consideration of mass and geometric shape of the links. Thus, it established that the proposed methodology can systematically generate novel, structurally distinct electrical switches.

M. Tech. (Engineering: Electrical, Department Electronic Engineering, Faculty of Engineering and Technology), Vaal University of Technology / The global trends towards energy efficiency have facilitated the need for technological advancements in the design and control of power electronic converters for energy processing. The proposed design is intended to make the practical implementation of converters easier. The development of a universal bidirectional galvanic isolated switch module will be used to drive any MOSFET or IGBT in any position in any topology whether the load is AC or DC. Semiconductor switches are required and are also integrated for fast switching times in power converter applications The structure of the power switch module consists of an opto-coupler which will provide an isolation barrier for maximum galvanic isolation between the control circuitry and power stage. It also consists of a high performance gate drive circuit for high speed switching applications with a floating supply. / Telkom South Africa Ltd, TFMC Pty Ltd, M-TEC, THRIP

Les bactéries utilisent un mode de communication appelé quorum sensing pour régulerl’expression des gènes en fonction de la densité de population et contrôler ainsi de façonmulticellulaire des processus tels que la sporulation, la compétence ou la virulence. Chez les bactériesà Gram-positif, le quorum sensing repose principalement sur la production, la sécrétion et la détectionde petits peptides de signalisation.Le projet porte sur l’étude du système quorum sensing: NprR/NprX chez Bacillus cereus, oùNprR est l’effecteur qui reconnait spécifiquement le peptide de signalisation NprX. NprR est uneprotéine bi-fonctionnelle. Seule, elle agit en tant qu’inhibiteur de la sporulation, en complexe avecNprX, elle perd sa fonction initiale au profit d’une activité facteur de transcription impliquée dans lavirulence. NprR appartient à une famille d’effecteurs de quorum sensing appelée RNPP (Rap, NprR,PlcR et PrgX) encore mal caractérisée au niveau structural. Mon projet de thèse a consisté en l’analysestructure-fonction du système NprR/NprX.Pour comprendre la régulation fonctionnelle de NprR par NprX, des études en solution (SECMALSet DLS) ont permis de mettre en évidence un switch moléculaire qui repose sur un changementd’oligomérisation. Ainsi NprX fait basculer NprR d’une conformation Apo dimérique à uneconformation compléxée tétramérique.L’étude structurale par cristallographie a aboutit à la résolution de la structure du complexeNprR/NprX. L’analyse de ce tétramère suggère la reconnaissance de 2 sites distincts sur l’ADN.L’étude structurale par SAXS, a quant à elle, permis de proposer une conformation dimérique de laforme Apo NprR, modèle conforté grâce à une étude par mutagénèse dirigée des résidus d’interface. Ils’agit d’un mode de dimérisation semblable à celui des protéines Rap (membres de la famille RNPP).La caractérisation par ITC de l’interaction NprR/NprX avec différentes formes du peptide,ainsi que l’analyse de la poche de fixation du complexe, ont permis de mieux comprendre la spécificitéd’interaction et de mettre en évidence deux résidus clés de l’effecteur : l’Asn275 essentielle à lafixation du peptide et l’Arg 126 essentielle à l’activation de la fonction facteur de transcription.Ces travaux ont contribué à une meilleure compréhension du système quorum sensingNprR/NprX grâce à l’élucidation du switch moléculaire contrôlé par NprX mais aussi à une meilleureconnaissance de la famille d’effecteurs RNPP. / Bacteria use a communication mode named quorum sensing to regulate gene expression depending on the population density and thus to control processes such as sporulation, competence or virulence in a multicellular manner. In Gram-positive bacteria, the quorum sensing relies mostly on the production, the secretion and the detection of small signaling peptides. The project focuses on the study of the quorum sensing system NprR/NprX in Bacillus cereus, where NprR is the effector, which recognizes specifically the signaling peptide NprX. NprR is a bi-functional protein. In the absence of peptide, it acts as a sporulation inhibitor while in complex with NprX, it acts as transcription factor implicated in virulence. NprR belongs to a family of quorum sensing effectors named RNPP (for the first identified members: Rap, NprR, PlcR and PrgX) still not well characterized at a structural level. My PhD project consisted to perform the structure/function analysis of the NprR/NprX system. To understand the functional regulation of NprR by NprX, I carried out different studies in solution (SEC-MALS and DLS). These results allowed me to highlight a molecular switch based on a changing of the oligomerisation state of the protein. NprX binding switches NprR from an Apo dimeric conformation to a tetrameric complex. The structural study by crystallography led to the resolution of the tetrameric NprR/NprX complex structure. The analysis of this tetramer suggests the recognition of 2 DNA binding sites. The structural study of the dimeric conformation of Apo NprR by SAXS, allowed me to propose a model similar to that of the Rap dimers (members of RNPP family). This model is supported by a directed mutagenesis study of interface residues. The characterization by ITC of the NprR/NprX interaction with different forms of the peptide, as well as the analysis of the binding pocket in the complex, led to a better understanding of the specificity of the interaction. Two key residues of the effector were highlighted: Asn275, essential to peptide binding and Arg126, essential to the activation of the transcription factor function. These results have contributed to a better understanding of the NprR/NprX quorum sensing system thanks to the elucidation of the molecular switch controlled by NprX but also in a better knowledge of the RNPP effectors family.

With the explosive growth of the wireless market, the demand for low-cost and highly-integrated radio frequency (RF) transceiver has been increased. Keeping up with this trend, complimentary metal-oxide-semiconductor (CMOS) has been spotlighted by virtue of its superior characteristics. However, there are challenges in achieving this goal, especially designing the transmitter portion. The objective of this research is to demonstrate the feasibility of fully integrated CMOS transmitter module which includes power amplifier (PA) and transmit/receive (T/R) switch by compensating for the intrinsic drawbacks of CMOS technology. As an effort to overcome the challenges, the high-power handling T/R switches are introduced as the first part of this dissertation. The proposed differential switch topology and feed-forward capacitor helps reducing the voltage stress over the switch devices, enabling a linear power transmission. With the high-power T/R switches, a new transmitter front-end topology - differential PA and T/R switch topology with the multi-section PA output matching network - is also proposed. The multi-stage PA output matching network assists to relieve the voltage stress over the switch device even more, by providing a low switch operating impedance. By analyzing the power performance and efficiency of entire transmitter module, design methodology for the high-power handling and efficient transmitter module is established. Finally, the research in this dissertation provides low-cost, high-power handling, and efficient CMOS RF transmitter module for wireless applications.

Moore's Law has helped Field Programmable Gate Arrays (FPGAs) scale continuously in speed, capacity and energy efficiency, allowing the integration of ever-larger systems into a single FPGA chip. This brings challenges to the productivity of developers in leveraging the sea of FPGA resources. Higher level of design abstractions and programming models are needed to improve the design productivity, which in turn require memory architectural supports on FPGAs. While previous efforts focus on computation-centric applications, we take a bandwidth-centric approach in designing memory systems. In particular, we investigate the scheduling, buffered switching and searching problems, which are common to a wide range of FPGA applications. Despite that the bandwidth problem has been extensively studied for general-purpose computing and application specific integrated circuit (ASIC) designs, the proposed techniques are often not applicable to FPGAs. In order to achieve optimized design implementations, designers need to take into consideration both the underlying FPGA physical characteristics as well as the requirements from applications. We therefore extract design requirements from four driving applications for the selected problems, and address them by exploiting the physical architectures and available resources of FPGAs. Towards solving the selected problems, we manage to advance state-of-the-art with a scheduling algorithm, a switch organization and a cache analytical model. These lead to performance improvements, resource savings and feasibilities of new approaches for well-known problems.

Moore's Law has helped Field Programmable Gate Arrays (FPGAs) scale continuously in speed, capacity and energy efficiency, allowing the integration of ever-larger systems into a single FPGA chip. This brings challenges to the productivity of developers in leveraging the sea of FPGA resources. Higher level of design abstractions and programming models are needed to improve the design productivity, which in turn require memory architectural supports on FPGAs. While previous efforts focus on computation-centric applications, we take a bandwidth-centric approach in designing memory systems. In particular, we investigate the scheduling, buffered switching and searching problems, which are common to a wide range of FPGA applications. Despite that the bandwidth problem has been extensively studied for general-purpose computing and application specific integrated circuit (ASIC) designs, the proposed techniques are often not applicable to FPGAs. In order to achieve optimized design implementations, designers need to take into consideration both the underlying FPGA physical characteristics as well as the requirements from applications. We therefore extract design requirements from four driving applications for the selected problems, and address them by exploiting the physical architectures and available resources of FPGAs. Towards solving the selected problems, we manage to advance state-of-the-art with a scheduling algorithm, a switch organization and a cache analytical model. These lead to performance improvements, resource savings and feasibilities of new approaches for well-known problems.

Les applications microélectroniques telles que les communications sans fil ou les radars nécessitent des traitements d’information avec des débits ou des résolutions de plus en plus élevés. Cela implique de travailler à des fréquences millimétriques voir sub-millimétriques. Grâce aux progrès des technologies silicium, des circuits intégrés travaillant dans les gammes de fréquences millimétriques émergent mais souffrent d'un manque de solution de caractérisation complète. Par exemple, il n’existe à ce jour aucun analyseur vectoriel de réseaux commercial qui soit capable de mesurer les paramètres S dans la bande G (140-220 GHz) en 4 ports. La caractérisation classique des circuits millimétriques en n ports (avec n>2) consiste alors à utiliser un analyseur vectoriel de réseaux 2 ports et à adapter les autres ports non utilisés à 50Ω. Par permutation circulaire, on arrive ainsi à extraire la matrice S d’un dispositif à n ports (avec n>2). Ce protocole de mesure est très long et délicat à mettre en place car il nécessite d’une part un investissement en appareil de mesure très couteux aux fréquences millimétriques et d’autre part de mettre en œuvre des méthodes de calibrage et de de-embedding précises et dédiées.Le travail développé dans le cadre de cette thèse a visé à intégrer dans la puce, des systèmes de caractérisation petits signaux (paramètres S) au plus près du Dispositif Sous Test (DST). Le fait d’être au plus près du DST permet de réduire les pertes d’insertion, de réduire l’amplitude des vecteurs d’erreurs et donc les erreurs résiduelles après calibrage. Par ailleurs, il est possible de mieux contrôler la puissance du signal envoyé et de considérer des méthodes de calibrage utilisant des charges intégrées, ce qui permet de réduire le temps de traitement et le cout. La technologie utilisée est la technologie SiGe BiCMOS 55 nm développée par la société STMicroelectronics, technologie particulièrement adaptée aux circuits en bande millimétrique. La solution développée dans cette thèse consiste à connecter le wafer avec des pointes de mesure qui amènent un signal hyperfréquence balayant le spectre 35-55 GHz. Une fois dans la puce, ce signal hyperfréquence est quadruplé en fréquence et amplifié afin d’atteindre des niveaux de puissance suffisant (bon rapport Signal/bruit) dans la bande G aux bornes du DST. Les paramètres de réflexion (S11 et S22) sont ensuite extraits grâce à deux coupleurs très directifs, placés sur l’entrée et la sortie du DST respectivement. Les sorties du coupleur sont ensuite ramenées en basse fréquence (0.5GHz < IF < 2.4 GHz) par l’intermédiaire de mélangeurs de fréquence.L’approche choisie est argumentée en se basant sur une étude des systèmes de mesures existant présentée dans la première partie de ce manuscrit. Puis la conception et la caractérisation de chacun des blocs composant le système sont détaillées : le quadrupleur de fréquence en bande G (constitué d’un doubleur de fréquence en bande W cascadé avec un doubleur de fréquence en bande G), le transfert switch en bande G permettant de commuter entre l’entrée et la sortie du DST, le coupleur directif à ondes lentes, les mélangeurs permettant de ramener les mesures en basse fréquence, etc…. Une fois tous les différents blocs présentés, le manuscrit aborde les deux systèmes de mesure conçus. Un premier système un port a été développé pour valider cette approche. Le second système conçu permet de mesurer un DST à deux ports (HBT). Ce second système conserve l’architecture hétérodyne du premier, intégrant en plus un transfert switch en bande G qui dirige le signal incident vers l’un des deux ports du DST. / Microelectronic applications such as wireless communications, radar or space detections require higher data rate resolutions, implying the use of millimeter wave and submillimeter frequencies. Thanks to the silicon technologies improvement, some microelectronic circuits are emerging working in the frequency range of 140-220 GHz (G-band) but they suffer from a lack of complete characterization tools involving costly investment. For example, there is currently no commercial vectorial network analyser (VNA) that can measure S parameters in the 4-ports G-band. The classical characterization of millimeter wave circuits in n ports (with n> 2) consists in using a vectorial analyzer of 2-ports networks and matching the other unused ports to 50Ω. By circular permutation, one thus manages to extract the S matrix from a device with n ports (with n> 2). This set up induces very long and difficult measurements and it requires on the one hand some very expensive measuring equipment at millimeter frequencies and on the other hand to implement accurate and dedicated calibration and de-embedding methods.Therefore, the work developed into this PhD study aimed to integrate in the die the measurement systems that would measure small signals "S-parameters" of the device under test (DUT). Being closer to the DST makes it possible to reduce the insertion losses, to reduce the amplitude of the error vectors and thus the residual errors after calibration. Moreover, it is possible to better control the power of the signal sent and to consider calibration methods using integrated loads, which reduces the time and cost processing. The technology used is the SiGe BiCMOS 55 nm technology developed by STMicroelectronics, a technology dedicated to RF and millimeter wave’s circuits.The system developed is a 1-port system. The solution developed consists on connecting the wafer with some probes and driving it with an external signal that spans the 35-55 GHz band. Once into the die, this signal is then quadrupled in frequency and amplified to reach good power level in G band at the DUT inputs. Some S-parameters (S11 and S22) are extracted from the DUT thanks to some very directive couplers designed respectively at the input and at the output of the DUT. The outputs of the couplers are then converted to low frequencies (IF =0.5-2.4 GHz) through passive frequency mixers.In a first part of the thesis manuscript, the way to work is argued, supported by a study of the state of the art concerning the measurement systems. Then, design and characterization of each blocks of the system are detailed: the frequency quadrupler in G band (composed of a W band frequency doubler, followed with a G band frequency doubler), the fully integrated transfer switch in G-band allowing driving the millimeter waves signal to the DUT input or to the DUT output, the directive couplers based on the slow wave lines, the frequency mixers used to bring back the results in base band frequency, etc… All the different blocks detailed, the measurement systems can be introduced. A first system, a one-port measurement system, has been designed as a proof of concept. Once the approach validated, a second system, two-ports measurement system, has been developed presenting an heterodyne architecture and a transfer switch in G band driving the input signal toward the DUT input or output.

De nombreux capteurs optiques, tels que les LIDARS, nécessitent des sources laser à la fois puissantes et spectralement fines. Dans ce contexte, l'objectif de ce projet est la réalisation de sources laser impulsionnelles intégrées, dont les caractéristiques spectrale et temporelle atteignent la limite théorique prédite par la théorie de Fourier. Pour ce faire, nous proposons une structure laser de type DFB avec un fonctionnement déclenché. La technologie de l'échange d'ions est retenue pour réaliser des guides d'onde amplificateurs dans un verre phosphate dopé ytterbium. La cavité DFB est ensuite constituée par gravure d'un réseau de Bragg à la surface des guides amplificateurs. Le comportement impulsionnel est obtenu par dépôt, sur la structure précédente, d'une couche mince d'acétate de cellulose dopée avec l'absorbant saturable BDN. Cette structure nous a permis d'obtenir des lasers impulsionnels monomodes longitudinaux dont les caractéristiques spectrales atteignent la limite de Fourier. Une étude en concentration d'absorbant saturable du superstrat montrent une variation de la durée des impulsions de 2,5 ns à 100 ns avec des puissances crêtes respectives de 30 W et 14 W. Nous parvenons donc à des spectres de largeur à mi-hauteur de valeur 9 MHz. Ces résultats ouvrent la voie à la réalisation de sources laser compactes pour les lidars embarqués. / Various optical sensors, such as LIDARs, need laser sources both powerful and narrow-linewidth. In this context, the aim of this project is the realization of integrated pulsed laser sources with a Fourier Transform Limited (FTL) spectrum. To do so, we propose a passively Q-switched DFB laser structure. Ion-exchange technology is used to realize amplifier waveguides on Ytterbium-doped phosphate glass. The DFB cavity is made by dry etching of a Bragg grating on the waveguides surface. The Q-Switched behavior is obtained by depositing a BDN-doped cellulose acetate coating layer, acting as a saturable absorber. This structure allowed us obtaining FTL single-frequency pulsed lasers. When studying the impact of BDN concentration, we observe pulses ranging from 2,5 ns with 40 W peak power, to 100 ns with 14 W peak power. Thus, our device FWHM linewidth goes down to 9 MHz. These results pave the way for the realisation of compact laser sources for embedded lidar systems.