In recent years, amorphous oxide semiconductors have been studied due to their superior characteristics, such as transparent property, high electron mobility exceeding 10 cm2/V¡Es, and can be fabricated on plastic substrates at low temperatures. According to these advantages, a-IGZO thin-film transistors are promising as next-generation electronic devices. Although a-IGZO TFTs have such unique properties, the electrical performances are strongly dependent on its environment such as oxygen, water and visible light. In this study, the electrical characteristics of a-IGZO TFTs under positive bias stress with different ambient gases have been discussed. In particular, the total duration of the negative gate bias applied on the switching transistor is larger than that of the positive gate bias in display application. Therefore, the electrical stability under negative bias stress is vital to investigate. Moreover, a-IGZO TFT regarded as a panel switch may be exposed to visible light for the application of liquid crystal display. The electrical stability under illumination of visible light is also important to study. Experiment results show that device characteristics are affected under water-containing oxygen ambience. We indicates that the existence of water molecules can assist more oxygen to adsorb on the a-IGZO surface than the case without water assisting. That cause the variation of transfer curve under positive bias stress. However, the degradations in subthreshold swing and threshold voltage are caused by the state-related adsorption of water molecules under negative bias stress. Furthermore, adsorbed oxygen on the surface of a-IGZO can be desorbed by illumination of visible light, leading to large variation in transfer curve.

The main contents of this thesis are improving a UWB LNA, and analyze the input-matching, the noise, and the gain. First we increase the width of the input transistor, and remove source-degeneration inductor. Those ways can increase the gain and reduce the noise of the circuit. In the input matching, we use a shunt capacitor, a series inductor, and the impedance of the transistor itself to achieve high frequency matching. The lower frequency matching is achieved by negative feedback resistor. The UWB LNA dissipates 10.14 mW power and achieves input return loss (S11) below -11.5 dB, output return loss (S22) below -11.9 dB, forward gain (S21) of 14.4¡Ó0.4 dB, reverse isolation (S12) below -26.7 dB, and noise figure (NF) of 2.6~3.5 dB over the 3.1~10.6 GHz band of interest. 1-dB compression point (P1dB) of -16.8 dBm and input third-order inter-modulation point (IIP3) of -8.1 dBm are achieved at 6.85 GHz.

This study explores whether the third-person effect caused by the published article in the Ptt Gossiping bulletin board. And the follow-up support to restrict the inappropriate content in the Ptt Gossiping bulletin board. Source of this study is use recommended system detected written by Expect language. It would detect popular articles and published articles. Pick a representative to do the test article.and place in the survey questionnaire online. The result shows: All of the four article have third person effect. Affect the follow¡Ðup support restrict the behavior of inappropriate content.

Many state agencies consider exclusive truck facilities to be an alternative to handle the safety and operational issues due to the increasing truck volumes. No such facilities exist, and there are no standard tools or procedures for measuring safety performance of an exclusive truck facility. This thesis aims at identifying factors that affect truck crashes, whose results could be used for better designing exclusive truck facilities. To accomplish the objectives of this thesis, five years’ roadway and crash data for Texas was collected to develop a comprehensive crash database. Negative binomial regression models were used to establish a relationship between truck crashes and various environmental, geometric and traffic variables. Separate models were developed for truck-related (involving at least one truck and another vehicle), truck-only (two trucks or more) and single-truck crashes. The results suggested that the percentage of trucks in Average Annual Daily Traffic (AADT), classification of the roadway (Rural/Urban), posted speed limit, surface condition, alignment and shoulder width are associated with truck crashes. It was observed that truck-related and truck-only crashes decreased as the percentage of trucks increased on freeway facilities. Based on conclusions derived from the literature review and statistical analyses, straight segments with wider shoulders and uniform grades are recommended for exclusive truck facilities. It is also recommended to provide ramps, horizontal and vertical curvature and signing based on truck size, driver eye height, braking ability and maneuverability. These models were developed using mixed-flow traffic data to understand the association of various factors with truck crashes. These models should not be used directly to estimate or predict truck crashes. Further analysis with more detailed data under different flow conditions might help in quantifying the safety performance of exclusive truck facilities.

Today's microwave circuits, whether for communication, radar, or testing systems, need compact tunable microwave filters. Since different microwave circuit applications have radically different size, power, insertion loss, rejection, vibration, and thermal requirements, new filter technologies with different balances between these requirements are always desirable. Negative Refractive Index (NRI) transmission media was discovered 10 years ago with the unique property of negative phase propagation. A literature review was conducted to identify potential NRI methods for filters and other devices, but no NRI tunable filters were found. To address this gap, a family of tunable NRI bandpass filters was simulated and constructed successfully using end-coupled zeroth order resonators. Tuning was accomplished by controlling the negative phase length of the NRI sections with varactors. The resulting L-band filters exhibited a 25-40 percent tunable range, no higher order resonances, and required only one fourth the length of a coupled-line filter constructed from traditional 180 degree microstrip resonators.

The Electron Energy Corporation (EEC) along with National Aeronautics and Space Administration (NASA) in collaboration with Vibration Control and Electro mechanics Lab (VCEL), Texas A & M University, College Station, TX are researching on high temperature permanent magnet based magnetic bearings. The magnetic bearings are made of high temperature resistant permanent magnets (up to 1000 degrees F). A test rig has been developed to test these magnetic bearings. The test rig mainly consists of two radial bearings, one axial thrust bearing and two catcher bearings. The test rig that the catcher bearing is inserted in is the first ultra-high temperature rig with permanent magnet biased magnetic bearings and motor. The magnetic bearings are permanent magnet based which is a novel concept. The Graphalloy bearings represent a new approach for ultra-high temperature backup bearing applications. One of the main objectives of this research is to insure the mechanical and electrical integrity for all components of the test rig. Some assemblies and accessories required for the whole assembly need to be designed. The assembly methods need to be designed. The preliminary tests for coefficient of friction, Young's modulus and thermal expansion characteristics for catcher bearing material need to be done. A dynamic model needs to be designed for studying and simulating the rotor drop of the shaft onto the catcher bearing using a finite element approach in MATLAB. The assembly of the test rig was completed successfully by developing assembly fixtures and assembly methods. The components of the test rig were tested before assembly. Other necessary systems like Sensor holder system, Graphalloy press fit system were designed, fabricated and tested. The catcher bearing material (Graphalloy) was tested for coefficient of friction and Young's modulus at room and high temperatures. The rotor drop was simulated by deriving a dynamic model, to study the effect of system parameters like clearance, coefficient of friction, negative stiffness, initial spin speed on system behavior. Increasing the friction increases the backward whirl and decreases the rotor stoppage time. Increasing the clearance reduces the stoppage time and increases the peak bearing force. Increasing the initial spin speed increases the rotor stoppage time. The maximum stress encountered for as built conditions is more than allowable limits.

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The modeling of electromagnetic phenomena described by the Maxwell's equations is of critical importance in many practical applications. The numerical simulation of these equations is challenging and much more involved than initially believed. Consequently, many discretization techniques, most of them quite complicated, have been proposed. In this dissertation, we present and analyze a new methodology for approximation of the time-harmonic Maxwell's equations. It is an extension of the negative-norm least-squares finite element approach which has been applied successfully to a variety of other problems. The main advantages of our method are that it uses simple, piecewise polynomial, finite element spaces, while giving quasi-optimal approximation, even for solutions with low regularity (such as the ones found in practical applications). The numerical solution can be efficiently computed using standard and well-known tools, such as iterative methods and eigensolvers for symmetric and positive definite systems (e.g. PCG and LOBPCG) and reconditioners for second-order problems (e.g. Multigrid). Additionally, approximation of varying polynomial degrees is allowed and spurious eigenmodes are provably avoided. We consider the following problems related to the Maxwell's equations in the frequency domain: the magnetostatic problem, the electrostatic problem, the eigenvalue problem and the full time-harmonic system. For each of these problems, we present a natural (very) weak variational formulation assuming minimal regularity of the solution. In each case, we prove error estimates for the approximation with two different discrete least-squares methods. We also show how to deal with problems posed on domains that are multiply connected or have multiple boundary components. Besides the theoretical analysis of the methods, the dissertation provides various numerical results in two and three dimensions that illustrate and support the theory.

The plant hormone ethylene plays an important role in plant growth, development, and physiology. One of the critical components of the ethylene signal transduction pathway, ctr1 (constitutive triple response), was identified using a particularly useful seedling screen that takes advantage of the profound effects ethylene has on etiolated seedlings, known as triple response. CTR1 is one of six Arabidopsis MAPKKKs that are related to the Raf kinases, and acts as a negative regulator of ethylene response. In this study, isolation and characterization of a family of CTR1-like genes in tomato is reported. Based on amino acid alignments and phylogenetic analysis, the tomato CTR1-like (LeCTR) genes are more similar to Arabidopsis CTR1 (AtCTR1) than any other MAPKKK sequences in the Arabidopsis genome. The capacity of the LeCTR genes to function as negative regulators in ethylene signal transduction was tested through complementation of the Arabidopsis ctr1-8 mutant. Quantitative real-time PCR was carried out to generate an expression profile for the CTR1-like gene family during different stages of development marked by increased ethylene biosynthesis, including fruit ripening. The possibility of a multi-gene family of CTR1-like genes in other species besides tomato was examined through mining of EST and genomic sequence databases. Based on nucleotide and amino acid identity, At4g24480 is most similar to AtCTR1 and could potentially represent a CTR1-like gene in Arabidopsis. Arabidopsis plants carrying a T-DNA insert in the At4g24480 locus were examined for abnormal ethylene response phenotypes including sensitivity to other hormones, signal molecules and abiotic stresses. Two mutant alleles, ctr1-1 and ctr1-8, containing mutations that disrupt kinase activity and receptor association, respectively, were examined for sensitivity to these same treatments in an effort to better characterize ethylene hormone and non-hormone interactions. They also served as controls to determine if At4g24480 indeed possessed CTR1-like function. Arabidopsis and tomato represent species with very distinct fruit ripening/maturation programs. The critical dependence on ethylene for fruit ripening in tomato might have resulted in alteration or modification of the ethylene signal transduction pathway relative to Arabidopsis. Plans to characterize individual functions of the LeCTR genes through over-expression and reduced expression in tomato are outlined.