Cette thèse s'intéresse au problème de préparation et de stabilisation de systèmes quantiques. Nous considérons des modèles correspondant à des expériences actuelles en électrodynamique quantique en cavité, circuits Josephson, et de contrôle quantique cohérent par laser femtoseconde. Nous posons les problèmes dans le contexte de la théorie du contrôle et nous proposons des lois de commande qui préparent ou stabilisent des états cibles. En particulier, nous nous intéressons à des états cibles qui n'ont pas d'analogue classique: des états superpositions et intriqués. De plus, nous proposons une commande pour la stabilisation d'un sous-espace de l'espace des états, contribuant ainsi au domaine de la correction d'erreur quantique. Ces résultats ont été obtenu en étroite collaboration avec des expérimentateurs. Des mesures expérimentales préliminaires sont en bon accord avec certaines prédictions théoriques de cette thèse.

Ce travail vise à étudier la rupture du gainage avec des essais mécaniques plus représentatifs des conditions RIA, en prenant en compte les blisters d'hydrures ainsi que le niveau élevé de biaxialité du chargement mécanique et des vitesses de déformation. Nous avons formé par thermodiffusion en laboratoire des blisters similaires à ceux observés sur des gaines de Zircaloy-4 irradiées en réacteur. Les caractérisations par métallographie, nanodureté, DRX et ERDA ont montré qu'un blister est constitué d'hydrures delta dont la concentration dans la matrice varie entre 80% et 100%, et que la matrice sous-jacente contient des hydrures radiaux. Nous avons modélisé la cinétique de croissance des blisters avec l'hystérésis de la limite de solubilité de l'hydrogène,puis défini le gradient thermique seuil permettant leur formation. Notre étude sur le comportement dilatométrique du zirconium hydruré montre le rôle important de la texture cristallographique du matériau, ce qui peut expliquer des différences de morphologie des blisters. En parallèle, des essais suivis par caméra infrarouge ont montré que des vitesses de déformation supérieures à 0,1/s induisent des échauffements locaux importants qui favorisent la localisation précoce de la déformation. Enfin, nous avons optimisé l'essai d'Expansion Due to Compression pour atteindre un niveau de biaxialité de déformation plane (essais HB-EDC et VHB-EDC), ce qui réduit fortement la déformation à rupture à 25°C et 350°C, mais seulement en l'absence de blisters. Un critère de rupture est proposé pour rendre compte de la baisse de ductilité des gaines en Zircaloy-4 non irradiées en présence de blisters.

Hot rolling process is heat input process. The heat energy in hot rolled steel coils can be utilized. At SSAB Strip Product Borlänge when the hot rolled steel coils came out of the hot rolling mill they are at the temperature range of 500°C to 800°C. Heat energy contained by the one hot rolled steel coil is about 1981Kwh whereas the total heat energy for the year 2008 is 230 GWh/year.The potential of heat is too much but the heat dissipation rate is too slow. Different factors on which heat dissipation rate depends are discussed.Three suggestions are proposed to collect the waste heat from hot rolled steel coils.The 2nd proposal in which water basin is suggested would help not only to collect the waste heat but to decrease in the cooling time.

0.18 um CMOS technology is increasingly used in design and implementation of full adder cells. Hence, there is a need for better understanding of the effects of different cell designs on cell performance, including power dissipation and time delays. This thesis contributes to better understanding of the behavior of single-bit full adder cells when low power-delay products are essential. Thirty one single-bit full adder cells have been implemented in Cadence tool suit and simulated using 0.18 µm CMOS technology to obtain a comprehensive study of the performance of the cells with respect to time (time-delays) and power consumption (power dissipation). Simulation method used for performance measurements has been carefully devised to achieve as accurate measurements as possible with respect to time delay and power dissipation. The method combines the simple measurement technique for obtaining accurate time-delays and power dissipation of a cell, and the transistor resizing technique that allows systematicallyresizing of transistors to achieve minimal power-delay product. The original technique of sizing of the transistors has been extended in this thesis for the purpose of the performance measurements to include both resizing the transistors in the critical path and resizing the transistors on the global level, and therefore efficiently obtain minimal power-delay product for every cell. The result of this performance study is an extensive knowledge of full adder cell behaviour with respect to time and power, including the limitations of the 0.18 µm CMOS technology when used in the area of full adder cells. Furthermore, the study identified full adder cell designs that demonstrated the best performance results with respect to power-delay products. In general, the complex performance simulation method in this thesis that combines the simulation of time delay and critical path transistor resizing provides the most accurate measurements and as such can be used in the future performance analysis of single-bit full adder cells.

It is the objective of this work to focus on heat dissipation in gallium nitride based solid-state logic devices as well as optoelectronic devices, a major technical challenge. With a direct band gap that is tunable through alloying between 0.7-3.8 eV, this material provides an enabling technology for power generation, telecommunications, power electronics, and advanced lighting sources. Previously, advances in these areas were limited by the availability of high quality material and growth methods, resulting in high dislocation densities and impurities. Within the last 40 years improvements in epitaxial growth methods such as lateral epitaxial overgrowth (LEO), hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE), and metal organic chemical vapor deposition (MOCVD), has enabled electron mobilities greater than 1600 cm2V/s, with dislocation densities less than 109/cm2. Increases in device performance with improved materials have now been associated with an increase in power dissipation (>1kW/cm2) that is limiting further development. In the following work thermophysical material of III-V semiconducting thin films and associated substrates are presented. Numerical modeling coupled with optical (micro-IR imaging and micro-Raman Spectroscopy) methods was utilized in order to study the heat carrier motion and the temperature distribution in an operating device. Results from temperature mapping experiments led to an analysis for design of next generation advancements in electronics packaging.

A 3-axis acoustic Doppler Velocimeter (ADV) with high sampling rate was used to measure the bed shear stress and turbulence under wave-current interaction conditions in this study. Experimental sites include laboratory tank, Love River in Kaohsiung and Howan coastal waters in Pingtung. Bed shear stress is estimated primarily by the inertial dissipation method, also by the turbulent kinetic energy method and eddy correlation method. Results of the laboratory experiments indicate that the bed shear stress increases as both the flow speed and wave height increase, and the flow speed is a more important factor. Field experiments can be divided into several types. The first type is under slow flows and calm waves. Love River is a typical condition of this type with turbid waters and a low flow speed. During the experimental period the ADV correlations reach 90% or more. Because the river flow is quite small, no significant bed shear stress is produced and u* is mostly less than 1 cm/s. As a result the deposition effect is much larger than erosion, thus a very thick layer of mud is formed on the riverbed. The observations in Howan in April 2010 also reveal the condition of slow flows and small waves, and the bed shear stress is also quite small. Due to the factors of clean coastal waters and weak turbulence in this season, the quality of ADV signals is poor. The second type is under large flows and small waves, as shown from the observations of Howan in April 2011, during which the maximum speed reached 25 cm/s and wave heights less than 20 cm. In this experiment the shear stress is large, the u* are mostly greater than 0.8 cm/s and the value of the drag coefficient is 0.0021; the ADV signals have good quality and the inertial sub-range is well defined. The third type is under weak flows and large waves. The observations of Howan in July 2011 show significant rainfall and maximum wave heights of 90 cm. In this case the u* are mostly centered around 1 cm/s. The acoustic backscatter intensity is positively correlated with the turbidity and wave height. Sizable bed shear stress induced by the orbital velocity of waves contributes a significant part to the total bed shear stress.

Internal waves occur in the interface between two layers of fluids with density stratification. In order to better understand the characteristics of continuous internal waves, a series of experiments were conducted in a laboratory tank. The upper and lower layers are fresh water of 15 cm thick and salt water of 30 cm thick, respectively. The periods of internal waves are 2.5, 5.5 and 6.6 sec. A micro-ADV is used to measure velocity profiles. Wave profiles at the density interface and the free surface are monitored respectively by an ultrasonic and capacitance wave gauges. Our results indicate that particle velocities (u and w) above and below the density interface have opposite directions. The speed is peaked near the density interface and it becomes weaker further away from the interface. Empirical Mode Decomposition is used to remove noise from the observed particle velocities, and the period is consistent with those derived from the interface elevations. The observed particle velocities also compare favorably with the theoretical results. When internal waves propagate without the interference of a sloping bottom, the turbulence induced is rather insignificant. The turbulence is more significant only near the density interface. With the existence of a sloping bottom, the internal waves gradually shoal and deform, the crest becomes sharp and steep, finally the waves become unstable, break and overturn. In this study the effect of bottom slope and the steepness of internal waves on the reflectivity of incoming waves are investigated. The reflectivity is smaller with gentler slope, and it increases and reaches a constant value with steeper slopes. The observed energy dissipation rate£`is higher near the slope. Three methods were used to estimate the energy dissipation rate and shear stress; namely, the inertial dissipation, the TKE and auto-correlation method. The£` estimated from the auto-correlation method is larger than that from the other two methods, but their trend is similar. The energy dissipation rate is found to increase with a gentler sloping bottom.

In the scope of the study, prismatic roughness elements with different longitudinal spacing and arrangements have been tested in a rectangular flume in order to reveal their effects on fundamental characteristics of a hydraulic jump. Two basic roughness types with altering arrangements have been tested. Roughness elements of the first type extends through the channel width against the flow with varying length and pitch ratios for different arrangements. The second type is of staggered essence and produced by piecing the roughness elements defined in the initial type into three parts which are equal in length. The doublet formed from the pieces on the sides is shifted to the consequent row to make two successive roughness rows encapsulate the channel span completely. Staggered roughness type is formed with the repetition of this arrangement along the flume. Independent of their type and arrangement, the entirety of roughness elements are embedded in the channel bed in order to avoid their protuberance into the flow, based on the presumption that the crests of the roughness elements levelled with the channel inlet would be less exposed to caving effects of flow than the protruding elements. In the study, influence of the proposed roughness elements on the fundamental engineering concerns as the length, height (tail water depth) and energy dissipation capacity of hydraulic jumps has been questioned in the light of empirical work and related literature on forced and smooth hydraulic jumps. At the final stage of the study, it was concluded that both strip and staggered roughness have positive effects on the characteristics of hydraulic jump given above. 3-7% more energy dissipation was observed in jumps on rough beds compared to classical hydraulic jumps. For tailwater dept reduction, whereas strip roughness provided 5-13%, staggered roughness led to 7-15% tailwater depth reduction compared to classical hydraulic jump. While strip roughness reduced jump length around 40%, 35-55% reduction was observed with staggered roughness when compared to classical hydraulic jump.

Previous studies have shown that screens may be utilized efficiently for dissipating the energy of water. For the present study, a series of experimental works are executed to investigate the tailwater and multiple screen effects on the energy dissipation through screens. Water flowing beneath a sliding gate is used to simulate the flow downstream of a hydraulic structure. In the present study, one double screen and two double screen arrangements with porosity of 40% and inclination angle of 90 degree is used. A tailwater gate structure is used to adjust the tailwater depth. The major parameters for the present study are upstream flow depth, tailwater gate height, location of the screen together with the supercritical upstream flow Froude number for a range covering from 5.0 to 22.5. The gate opening simulating a hydraulic structure is adjusted at heights of 2 cm and 3 cm during the study. The results of the experiments show that the tailwater depth has no significant additional contribution on the energy dissipation, whereas multiple screen arrangement dissipates more energy as compared to one double screen arrangement.

Seismic provisions for steel buildings present limiting width-thickness and slenderness ratios for bracing members. Most of these limits were established based on experimental observations. The number of experimental studies is limited due to the costs associated with them. With the rapid increase in computing power / however, it is now possible to conduct finite element simulation of brace components using personal computers. A finite element study has been undertaken to evaluate the aforementioned limits for pin-ended pipe section steel braces. Fifty four tubular pipe brace models possessing different diameter-to-thickness ratios varying from 5 to 30 and slenderness ratios varying from 40 to 200 were analyzed. The effect of cyclic hardening modulus on the response of braces was explored. In all analysis, the models were subjected to reversed cyclic displacements up to ten times the yield displacement. Local buckling was traced during the loading history using a criterion based on local strains. Results are presented in terms of the ductility level attained by the member at the onset of local buckling. It is shown that local buckling of the section is influenced by the diameter-to-thickness and the slenderness ratios of the member. Moreover, the amount of hardening modulus was found to affect the local buckling response significantly. The need to include this material property into seismic provisions is demonstrated. Finally, the hysteretic energy dissipated by the member was quantified for each displacement excursion.