This thesis investigates optimization of advanced telecommunication algorithms from power and performance perspectives. The algorithms chosen are MIMO and LDPC. MIMO is implemented in custom ASIC for power optimization and LDPC is implemented on dynamically reconfigurable fabric for both power and performance optimization. Both MIMO and LDPC are considered computational bottlenecks of current and future wireless standards such as IEEE 802.11n for Wi-Fi and IEEE 802.16 for WiMax applications. Optimization of these algorithms is carried out separately. The thesis is organized implicitly in two parts. The first part presents selection and analysis of the VBLAST receiver used in MIMO wireless system from custom ASIC perspective and identifies those processing elements that consume larger area as well as power due to complex signal processing. The thesis models a scalable VBLAST architecture based on MMSE nulling criteria assuming block rayleigh flat fading channel. After identifying the major area and power consuming blocks, it proposes low power and area efficient VLSI architectures for the three building blocks of VBLAST namely Pseudo Inverse, Sorting and NULLing & Cancellation modules assuming a 4x4 MIMO system. The thesis applies dynamic power management, algebraic transformation (strength reduction), resource sharing, clock gating, algorithmic modification, operation substitution, redundant arithmetic and bus encoding as the low power techniques applied at different levels of design abstraction ranging from system to architecture, to reduce power consumption. It also presents novel architectures not only for the constituent blocks but also for the whole receiver. It builds the low power VBLAST receiver for single carrier and provides its area, power and performance figures. It then investigates into the practicality and feasibility of VBLAST into an OFDM environment. It provides estimated data with respect to silicon real estate and throughput from which conclusion can easily be drawn about the feasibility of VBLAST in a multi carrier environment. The second part of the thesis presents novel architectures for the real time adaptive LDPC encoder and decoder as specified in IEEE 802.16E standard for WiMax application. It also presents optimizations of encoder as well as decoder on RICA (Reconfigurable Instruction Cell Architecture). It has searched an optimized way of storing the H matrices that reduces the memory by 20 times. It uses Loop unrolling to distribute the instructions spatially depending upon the available resources to execute them concurrently to as much as possible. The parallel memory banks and distributed registers inside RICA allow good reduction in memory access time. This together with hardware pipelining provides substantial potential for optimizing algorithms from power and performance perspectives. The thesis also suggests ways of improvements inside RICA architecture.

Airpower capability and military technology have created a vision of airpower that focuses on the lethality of weaponry instead of the use of that weaponry as a political tool. Unfortunately, such a lethality-focused force optimized to fight interstate conflicts, by definition, ensures that this force is sub-optimal for waging wars at the sub-state level. Small wars are conflicts where the political and diplomatic context, and not the military disposition of the combatants, is usually the determining factor. Following World War II there emerged an era of insurgencies and limited wars of territorial dispute. These small wars required new operational and tactical innovations involving the use of airpower, as the very nature of these wars differed from conventional conflict towards which most of aviation was geared. This thesis analyzes six historical cases involving the use of airpower across a wide spectrum of small wars through the lens of an analytical framework for countering insurgencies. While the typologies of no two conflicts are identical, and the application of airpower equally varied, this work provides fundamental assertions and implications regarding the proper use of airpower for waging war at this level. / US Air Force (USAF) author.

This thesis establishes an analytical framework for identifying and discussing strategic factors considered when developing the Hungarian Special Forces (HUNSF) as a new "niche" capability of the Hungarian Defense Forces (HDF). Although the findings have broad application, focus is on the Hungarian Special Forces unit. Key questions are how will factors such as the strategic environment, changes in the nature of war and characteristics of potential adversaries affect the development of a conceptual framework for the Hungarian Special Forces? Should unconventional warfare (which is a capability gap in the HDF at present) be an official task for the future Hungarian military forces and specifically a primary task for the HUNSF? Central to this study are factors found in the strategic environment, such as Hungary's affiliation with NATO and the EU. The thesis concentrates on defining the tasks for HUNSF, and based on these tasks, develops an organizational framework for the HUNSF capability. This framework includes training and command and control. The constantly changing security environment will also call for adjustments to the concept of HUNSF in the future; therefore, a vision for the HUNSF is incorporated into the thesis to provide flexibility and guidance for capability development in the future. A key finding of the thesis is that HUNSF has the potential to contribute to the fight against the many new security challenges and achieve many of the objectives posited in existing military transformation strategies, most importantly an unconventional warfare capability.

This thesis describes the implementation of an ELINT algorithm for the detection and classification of Low Probability of Intercept (LPI) signals. The algorithm was coded in the C programming language and executed on a Field Programmable Gate Array based reconfigurable computer; the SRC-6 manufactured by SRC Computers, Inc. Specifically, this thesis focuses on the preprocessing stage of an LPI signal processing algorithm. This stage receives a detected signal that has been run through a Quadrature Mirror Filter Bank and outputs the preprocessed signal for classification by a neural network. A major value of this study comes from comparing the performance of the reconfigurable computer to that of supercomputers and embedded systems that are currently used to solve the signal processing needs of the United States Navy. / US Navy (USN) author.

<p> This work contributes to the study of magnetic interactions in the low-dimensional antiferromagnets <i>M</i>(Sb,Ta)₂O₆, where <i> M</i> is a transition metal. By virtue of the trirutile structure, <i> M-O-O-M</i> chains propagate along [110] at <i>z</i> = 0 and [1<span style="text-decoration:overline">1</span>0] at <i>z</i> = 1/2 of the unit cell. These chains are separated along [001] by sheets of weakly-interacting diamagnetic ions. The spin-exchange coupling perpendicular to the chains is weak, permitting the low-dimensional classification. Single crystals have been grown using chemical vapor deposition and the floating zone method. Magnetization, in-field heat capacity, and high-resolution thermal expansion measurements have been performed along various axes, revealing significant anisotropy due to the peculiar magnetic structures and low dimensionality.</p><p> The Neel temperature, <i>T_N,</i> at which long-range order occurs is found to be unstable against the application of magnetic field above 2 T. Large fields tend to lower <i>T_N</i> of the set of moments with projections along the applied field. Moments which are aligned perpendicular to the field are significantly less affected. This can lead to the formation of a secondary peak in heat capacity when magnetic field is along either [110] or [1<span style="text-decoration:overline">1</span>0]. The change in heat capacity at the location of the newly formed peak means there is a change in entropy, which depends upon the direction of applied field with respect to the magnetic moments. Consequently, an anisotropic magnetocaloric effect arises due to the unique magnetic structure. The anisotropic nature of this effect has potential applications in magnetic refrigeration.</p>

The extent of weathering incongruency during soil formation from rock controls local carbon and nutrient cycling in ecosystems, as well as the evolution of hydrologic flow paths. Prior studies of basalt weathering, including those that have quantified the dynamics of well-mixed, bench-scale laboratory reactors or characterized the structure and integrated response of field systems, indicate a strong influence of system scale on weathering rate and trajectory. For example, integrated catchment response tends to produce lower weathering rates than do well mixed reactors, but the mechanisms underlying these disparities remain unclear. Here we present pore water geochemistry and physical sensor data gathered during two controlled rainfall-runoff events on a large-scale convergent model hillslope mantled with 1 m uniform depth of granular basaltic porous media. The dense sampler and sensor array (1488 samplers and sensors embedded in 330 m(3) of basalt) showed that rainfall-induced dissolution of basaltic glass produced supersaturation of pore waters with respect to multiple secondary solids including allophane, gibbsite, ferrihydrite, birnessite and calcite. The spatial distribution of saturation state was heterogeneous, suggesting an accumulation of solutes leading to precipitation of secondary solids along hydrologic flow paths. Rapid dissolution of primary silicates was widespread throughout the entire hillslope, irrespective of up-gradient flowpath length. However, coherent spatial variations in solution chemistry and saturation indices were observed in depth profiles and between distinct topographic regions of the hillslope. Colloids (110-2000 nm) enriched in iron (Fe), aluminum (Al), and phosphorus (P) were mobile in soil pore waters.

This thesis proposes a continuous low-thrust guidance and control strategy for satellite formation-flying. Stabilizing feedback based on mean relative orbit elements and Lyapunov theory is used. A novel feedback gain matrix inspired by the fuel-optimal impulsive solution is designed to achieve near-optimal fuel consumption. A reference governor is developed to autonomously guide the spacecraft through the relative state-space in order to allow for arbitrarily constrained satellite formations. Constraints include desired  thrust levels, time constraints, passive collision avoidance and locally constrained state-space areas. Keplerian dynamics are leveraged to further decrease fuel consumption. Simulations show fuel consumptions of only 4% higher delta-v than the fuel-optimal impulsive solution. The proposed control and guidance strategy is tested in a high-fidelity orbit propagation simulation using MATLAB/Simulink. Numerical simulations include orbit perturbations such as atmospheric drag, high-order geopotential, solar radiation pressure and third-body (Moon and Sun) effects. Test cases include reconfiguration scenarios with imposed wall, thrust and time constraints and a formation maintenance experiment as flown by TanDEM-X, the TanDEM-X Autonomous Formation-Flying (TAFF) experiment.

A detailed examination of low visibility (LV) occurrences and the weather types that cause low visibility, with a focus on fog, was performed for five weather stations in the western Canadian Arctic, in the vicinity of the Amundsen Gulf area of the eastern Beaufort Sea. A series of climatologies were developed that established patterns of LV occurrence as a proportion of all observations and as a function of LV events caused by fog. Frequency climatologies for other weather types were also performed; in particular, for snow, blowing snow, rain, and drizzle. Annual climatologies were used to identify trends in several weather parameters over the 1980-2015 period of study. Monthlies were used to identify typical patterns of occurrence over the course of a year, and hourlies over the course of a day. A dataset of multi-hour fog events was also created; some of these were related to synoptic patterns. Analysis was also broken down by season. Results indicate several things. Monthly climatologies showed considerable diversity across the study area. Three distinct groupings were noted: Tuktoyaktuk and Ulukhaktok with a maximum frequency of LV conditions in February, Aklavik and Inuvik with a maxiumum frequency in October, and Sachs Harbour in August. The February maximum in Tuktoyaktuk and Ulukhaktok was related to cold air temperatures combined with small amounts of moisture from sea ice leads. The Alkavik and Inuvik October maximum was related to moisture advected over land from remaining open water, as well as diurnal snow melt adding moisture to the boundary layer that condenses as the evening cools off. The August maximum in Sachs Harbour is a reflection of proximity to open water and cold air temperatures. Hourly climatologies in the spring/fall season showed most stations have maximum occurrence of LV events caused by fog in the early morning. This is a radiative effect; cooling overnight causes radiation fog that peaks in occurrence just as morning begins. This peak is pushed into the midday in the winter, and is much weaker in the summer, both reflections of the changing pattern of daylight hours. / Graduate

Findings are presented from matched case-control studies of risk factors for diabetes, cryptorchidism and inguinal hernia in children using routine data collected by the Oxford Record Linkage Study since 1965. There were 315 cases born 1965-85 in the diabetes study, 947 and 1449 cases in studies of cryptorchidism diagnosed at birth and at orchidopexy respectively, and 1701 male and 347 female cases in the study of inguinal hernia. Each case was individually matched with up to eight controls on sex, year, and hospital or place of birth. A potential bias caused by differential migration of cases and controls was identified. A sample of 753 controls born in Oxfordshire was checked against the Oxfordshire Family Health Services Authority register to determine migration out of the study area in relation to perinatal risk factors. A general procedure was developed to estimate the strength of the migration bias. Pre-eclampsia was identified as a significant pre-natal risk factor for diabetes. The studies of cryptorchidism identified significantly raised risks with low birth weight, low social class and breech presentation. The results suggested that asymmetric growth retardation in the third trimester may be involved in the aetiology of undescended testes that do not spontaneously descend in later life. Analysis of risk factors among siblings of cases and controls suggested that permanent changes to the mother may occur around the time of the pregnancy involving the affected child. Low birth weight, short gestation and smoking during pregnancy were associated with significantly raised risks of inguinal hernia among boys. Among girls the results were similar, suggesting that mechanisms independent of the sex of the child may be important in the aetiology of this condition. Estimates of disease risk in siblings showed a strong familial aggregation, especially among girls.

Syftet med den här studien är att studera vindprofiler och klassificera Low Level Jets (LLJ) och även analysera den termiska vinden över Östergarnsholm. Östergarnsholm är en liten ö som ligger 4 kilometer öster om Gotland. Viseringar och sonderingar från åren 1995 till 2001 samt år 2003 har använts. Det kriteriet som har använts för att klassificera LLJs är att det ska finnas ett vindhastighetsmaximum under 500 meters höjd. De undersökta orsakerna till uppkomsten av en LLJ är sjöbris, tröghetssvängning och termisk vind. För att kunna ta ut LLJs orsakade av sjöbris har vindprofiler över hela dygn använts. Vindens vridning vid marken, under dagen, jämfört med den överlagrade vindens riktning vid 2000 meters höjd har undersökts. LLJs som uppkommit på grund av tröghetssvängning har analyserats. Metoden för tröghetssvängning bygger på att analysera den geostrofiska vindens hastighet och vindriktning för att sedan kunna räkna ut hur vinden har blåst och var en eventuell LLJ skulle kunna bildas. Här har vindriktningar mellan 20º – 220º använts eftersom det medför att vinden då blåser från havet. Resterande vindriktningar medför att vinden har blåst över Gotland vilket resulterar i att en eventuell tröghetssvängning skulle störas och en LLJ skulle försvinna innan den når Östergarnsholm. Vindhastigeter och vindriktningar har jämförts med teoretiskt uträknade värden från tryckmätningar. Från alla 245 viseringar fanns 103 vindprofiler med LLJs. Utav dessa var 27 stycken, under 12 dygn, orsakade av sjöbris. Hur många LLJs som bildats av tröghetssvängning är oklart. Detta eftersom olika resultat erhålles beroende på om vindhastigheter och vindriktningar tas från viseringarna eller är beräknade från tryckmätningar, samt om beräkningarna av transporttiden sker med raka eller krökta trajektorier. Totalt hittades 9 LLJs som orsakats av tröghetssvängning. Metoden som använts för att analysera tröghetssvängning ger förmodligen bättre resultat över land än över hav. Detta eftersom det är svårt att mäta de exakta vindförhållandena längs luftens transport över hav. Den geostrofiska vindens ändring med höjden över ön, det vill säga den termiska vinden, har analyserats genom att undersöka alla vindprofiler, även de utan LLJs. Dessa har jämförts med den geostrofiska vinden beräknad från tryckmätningar, som representerar vinden vid marken, för att se om det uppkommer termiska vindar över Östergarnsholm. En LLJ som orsakats av termisk vind uppkommer när den geostrofiska vinden avtar med höjden, det vill säga vid negativ termisk vind. Antalet fall där den geostrofiska vinden avtar med höjden och där vinden är konstant med höjden var ungefär lika många. Däremot fanns något fler fall där den geostrofiska vinden ökade med höjden, dessa uppgick även till högre hastigheter än när vinden avtog med höjden. Det finns inget samband för vindvridningen med höjden då det förekommer LLJs på grund av termisk vind. Däremot finns ett tydligt samband mellan den negativa termiska vindens u- och v-komponent och den geostrofiska vindens u- respektive v-komponent. I båda fallen så tenderar vinden att gå mot noll med höjden. Totalt hittades 41 LLJs som var orsakade av termisk vind. Vid ungefär 50% av alla vindprofiler, både när den geostrofiska vinden avtog och ökade med höjden, var den termiska vindens nord-sydliga komposant positiv och den ost-västliga komposanten negativ. Detta ger att den varmare luften finns i nordost. / The aim of this study is to classify Low Level Jets (LLJ) and analyze the thermal wind over Östergarnsholm. Östergarnsholm is a small island that is situated 4 kilometres east of Gotland in the Baltic Sea. Pibal trackings and soundings from 1995 to 2001 and 2003 have been used in the study. The criteria that have been used to classify the LLJs is that there must be a maximum of the wind speed below 500 meters. Wind profiles from a specific day have been used to determine if the LLJs is caused by sea breeze. The shift of wind direction at ground level, during the day, compared to the geostrophic wind at 2000 meters has been analyzed. LLJs caused by internal oscillation have been analyzed. In the used method the geostrophic wind speed and wind direction have been analyzed to determine how the wind has blown and where a LLJ possibly could be formed. Only wind directions between 20º and 220º have been used to avoid that the wind should have passed Gotland. If the winds have passed Gotland the internal oscillation has been disturbed and no LLJ can appear. Measured wind speeds and directions have been compared to theoretical values from pressure measurements. 103 wind profiles with LLJs were found from all pibal trackings. In 27 of these pibal trackings, from 12 days, were LLJs caused by sea breeze. It is difficult to say how many LLJs that are caused by an internal oscillation. This due to the different results obtained when using wind speeds and wind directions from pibal trackings or pressure measurements. Also using straight line trajectories or trajectories following the isobars gives different results. Totally 9 LLJs were found, caused by an internal oscillation. Probably this way of analyze the internal oscillations is a better method for measurements over land than over sea. This due to the difficulties in measuring the exact wind speed and wind direction over the whole traveling distance over sea. The thermal wind over the island has been analyzed by studying all pibal trackings, even those without LLJs. The pibal trackings have been compared to the geostrophic wind calculated from pressure measurements to determine if thermal winds occur over Östergarnsholm. A LLJ caused by thermal wind occur when the geostrophic wind decreese with height, i.e. negative thermal wind. There was no difference in the amount of negative thermal winds and cases with no thermal wind. There were a few more positive thermal winds and they had higher wind speeds than the negative ones. There is no connection in the shift of wind direction when there is a LLJ caused by thermal wind. But there is a significant connection between the u- and v-component of the negative thermal winds and the u- and v-component of the geostrophic wind. In both cases the geostrophic wind tends to decreese towards zero with height. 41 of all LLJs were caused by thermal winds. About 50% of both negative and positive thermal winds have a positive v-component and a negative u-component. This means that the warmer region is in the north east.