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Starting with a comprehensive literature survey, the work reported in the thesis consists of a mathematical analysis and then measurements of the 3rd- and 5th-order intermodulation products produced by the non-linearities of a large number of various metal contacts. The experimental study concentrated on the intermodulation products generated at the contacting faces between similar and dissimilar metals and included contact materials of copper, beryllium copper, brass, oxygen free copper, oxygen free nickel, mild steel, stainless steel (EN58B), duraluminium and twelve home-made steels with various compositions. The measurements were carried out for the first time at L-band frequencies on a good experimental arrangement. The fundamental excitation frequencies were f1 = 1.3GHz and f2 = 1 7GHz and the 3rd- and 5th-order intermodulation products were 2f2 - f1 = 2.1GHz and 3f2 - 2fl = 2.5GHz respectively. The quantitative studies were mainly concerned with the variation of the 3rd- and 5th-order intermodulation product levels with the power levels of the fundamental signals and with the axial force applied to the contact.

Although many fracture models are based on two-dimensional plane strain approximations, accurately predicting fracture propagation geometry requires accounting for the three-dimensional aspects of fractures. In this study, we implemented 3-D displacement discontinuity (DD) boundary element modeling to investigate the following intrinsically 3-D natural or hydraulic fracture propagation problems: the effect of fracture height on lateral propagation of vertical natural fractures, joint development in the vicinity of normal faults, and hydraulic fracture height growth and non-planar propagation paths. Fracture propagation is controlled by stress intensity factor (SIF) and its determination plays a central role in LEFM. The DD modeling is used to evaluate SIF in Mode I, II and III at the tip of an arbitrarily-shaped embedded crack by using crack-tip element displacement discontinuity. We examine the accuracy of SIF calculation is for rectangular, penny-shaped, and elliptical planar cracks. Using the aforementioned model for lateral propagation of overlapping fractures shows that the curving path of overlapping fractures is strongly influenced by the spacing-to-height ratio of fractures, as well as the differential stress magnitude. We show that the angle of intersection between two non-coincident but parallel en-echelon fractures depends strongly on the fracture height-to-spacing ratio, with intersection angles being asymptotic for "tall" fractures (large height-to-spacing ratios) and nearly orthogonal for "short" fractures. Stress perturbation around normal faults is three-dimensionally heterogeneous. That perturbation can result in joint development at the vicinity of normal faults. We examine the geometrical relationship between genetically related normal faults and joints in various geologic environments by considering a published case study of fault-related joints in the Arches National Park region, Utah. The results show that joint orientation is dependent on vertical position with respect to the normal fault, the spacing-to-height ratio of sub-parallel normal faults, and Poisson's ratio of the media. Our calculations represent a more physically reasonable match to measured field data than previously published, and we also identify a new mechanism to explain the driving stress for opening mode fracture propagation upon burial of quasi-elastic rocks. Hydraulic fractures may not necessarily start perpendicular to the minimum horizontal remote stress. We use the developed fracture propagation model to explain abnormality in the geometry of fracturing from misaligned horizontal wellbores. Results show that the misalignment causes non-planar lateral propagation and restriction in fracture height and fracture width in wellbore part.

Proteins are the ultimate laborers in biological systems. The behavior of a cell is governed by the dynamic interactions between thousands of proteins; a tissue is governed by the interactions of thousands of cells; and an organism is governed by the interaction of multiple tissues. The maintenance of protein homeostasis (proteostasis) is therefore a critical component of proper cellular function and the response to constantly changing environmental signals. The dynamic proteomic approach used in these rodent studies involves the administration of 2H2O in the drinking water to achieve a target body water enrichment of 5%. During the labeling period, in vivo protein synthesis occurs, resulting in the creation of "heavy" proteins identical to their "light" counterparts in function, differing only in the incorporation of deuterium atoms at specific positions in the constituent amino acids from which they are comprised. These peptides are then resolved by high-affinity liquid chromatography mass spectrometry (LC-MS), resulting in the identification of hundreds to thousands of proteins from a single tissue sample. Using this experimental approach, we investigated the effect of calorie restriction (CR), insulin resistance, and diabetes on dynamic protein synthesis. To date, CR has taken center stage as the most effective intervention in lifespan extension. Despite this, the biological mechanisms underlying increased health and longevity have yet to be fully described. While a growing body of evidence suggests that CR promotes significant gain-of-function attributes in mitochondria, a verdict on whether CR promotes mitochondrial biogenesis has not been established. In order to elucidate the controversy in the field regarding the response of mitochondria to reduced energy intake, we designed an experiment to study the effect of long-term CR on hepatic protein turnover. Our data provide conclusive evidence that mitochondrial protein turnover, concentration, and overall flux are reduced in response to CR, and may play central a role in mediating the health and longevity benefits of reduced energy intake.Insulin resistance and islet cell failure are the two fundamental processes underlying type 2 diabetes. Alterations in mitochondrial protein turnover have been implicated in the pathology of type 2 diabetes, however the specific effect of insulin resistance and diabetes on the intracellular dynamic islet proteome have yet to be described. We investigated the effects of insulin resistance and diabetes on the synthesis of proteins from isolated rat islets for the first time, using both 2H2O (heavy water) labeling and SILAM quantitative proteomics. Using this approach, we measured fractional and absolute synthesis rates of cytoskeletal, glycolytic, mitochondrial, ER, and ribosomal proteins, the principal pathways responsible for glucose stimulated insulin secretion (GSIS). We found that insulin resistance increased the fractional synthesis rates (FSR) of 97% of all measured islet proteins, and the subsequent transition to diabetes resulted in the selective impairment of ribosomal protein synthesis. Our findings suggest that the rapid rate of islet cell proliferation due to insulin resistance is accompanied by increased fractional and absolute synthesis of critical GSIS proteins, and that the failure of islets results mainly in impaired ribosomal pathway flux, independent of alterations in mitochondrial metabolism. Our data suggest that the rapid rate of islet cell proliferation due to insulin resistance is accompanied by increased fractional and absolute synthesis of critical GSIS components, and that the failure of islet cells in diabetes results mainly in impaired ribosomal pathway flux, independent of alterations in mitochondrial protein metabolism.

Aerospace systems such as aircraft or missiles are subject to environmental and dynamical uncertainties. These uncertainties can alter the performance and stability of these systems. Adaptive control offers a useful means for controlling systems in the presence of uncertainties. However, very often adaptive controllers require more control effort than the actuator limits allow. In this thesis the original work of others on single input single output adaptive control in the presence of actuator amplitude limits is extended to multi-input systems. The Lyapunov based stability analysis is presented. Finally, the resultant technique is applied to aircraft and missile longitudinal motion. Simulation results show satisfactory tracking of the states of modified reference system.

Design, fabrication and testing of a micromachined, high aspect-ratio high-performance polysilicon vibrating ring gyroscope are presented. The polysilicon vibrating ring is 1mm in diameter, 80mum thick and 4mum wide. It is supported by eight semi-circular springs to a center post that is 120mum in diameter. Sixteen electrodes are evenly located around the structure to drive, sense and electronically tune the ring structure. To sense rotation, the ring is electrostatically vibrated into its first in-plane flexural vibration mode and the position of the node lines are capacitively monitored. In this dissertation, a detailed analysis has been performed to determine the overall sensitivity of the vibrating ring gyroscope and identify its scaling limits. Several aspects of this analysis apply to other gyroscope sensing structures. Based on this analysis, a new single-wafer, high aspect ratio, dry-release poly-silicon microfabrication technology has been developed to implement sensor structures that provide all the features required for achieving the desired high performance. This process utilizes polysilicon as the structural element with its superior and homogenous material properties and is capable of producing very thick vertical polysilicon and silicon structures using Deep Reactive Ion Etching of silicon. Various size capacitive air-gaps ranging from sub-micron to tens of micron can be realized in this technology. This process is capable of producing silicon electrodes as tall as the main body structure with a simple fabrication process that eliminates the limitations of the previous technologies. Using a bent-beam strain gauge sensor, residual stress in 80mum thick, 4mum wide trench-refilled vertical polysilicon beams has been measured to be zero. 300mum long clamped-clamped beam resonators have shown quality factors as high as 85,000 in 1mTorr vacuum. A prototype 1.7 x 1.7 mm2 Polysilicon Ring Gyroscope (PRG) fabricated using the above technology has been tested in hybrid format. An open-loop sensitivity of 200muV/deg/sec in a dynamic range of +/-250 deg/sec was measured under low vacuum level for a prototype device. The resolution of the sensor is currently limited by the noise from the circuitry and for a prototype sensor with a quality factor (Q) of 1150 and parasitic capacitances of 2pF was measured to be less than 1 deg/sec in 1Hz bandwidth. Elimination of the parasitic capacitances and improvement in the quality factor of the ring structure are expected to reduce the resolution to 0.01 deg/sec in 1Hz bandwidth. By increasing the drive amplitude to 1mum in an asymmetric single ring gyroscope design, a minimum detectable signal of 5 x 10 -3 deg/sec (18 deg/h) in a 10Hz bandwidth can be achieved. Recommendations for improving the sensor performance to tactical and inertial grade levels are discussed at the end.

This paper presents a framework for exploring the sustainability of U.S. domestic budget deficits in the presence of the currently experienced capital inflows. A 'sustainable' deficit-financing policy is defined as one in which the combination of debt-financing and seigniorage precludes the creation of a large unanticipated inflation to wipe out the debt in real terms. The model implemented is a rational expectations model of the open economy and two separate cases are analyzed. In Case I, domestic money creation is held 'fixed' and any increases in the deficit are financed by the sale of one-year discounted government bonds to domestic and foreign residents. In Case II domestic money and bonds are both endogenously determined. The asset market, in both the cases, is characterized by perfect capital mobility as defined by uncovered nominal interest parity. Real interest parity, however, does not exist as domestic and foreign goods are not perfect substitutes. In Case I, the solution of the domestic price level exhibits price-neutrality with respect to the deficits. The nominal and real exchange rates, however, are found to appreciate with increases in deficits and the situation is aggravated further by an exodus of domestic real wealth. In Case II, on the other hand, deficits are found to be inflationary and both nominal and real exchange rates depreciate with increases in the deficit. Furthermore, increases in the amount of debt being rolled over cause even greater upward pressures on domestic inflation and result in the further weakening of the dollar. The solutions also provide us with an expression for the maximum amount of debt that can be rolled over without causing the domestic price level to explode or the currency to collapse. This 'critical value' of debt is found to bear an inverse relationship to the rate of growth of the domestic deficit. Bond-financed deficits are therefore non-sustainable in both the cases discussed, and the arithmetic, it seems, is unpleasant indeed.

This investigation is designed to provide new information concerning the effects of toxic levels of manganese on the following blood components of sheep: plasma and erythrocyte (red blood cells) iron and manganese; erythrocyte and leucocyte (white blood cells) counts; hemoglobin concentrations and packed cell volumes; Wintrobe indices; differential counts and body weights.