Electronic power devices made of silicon carbide promisesuperior performance over today's silicon devices due toinherent material properties. As a result of the material'swide band gap of 3.2eV, high thermal conductivity, itsmechanical and chemical stability and a high critical electricfield, 4H-silicon carbide devices have the potential to be usedat elevated temperatures and in harsh environments. Shortercarrier lifetimes and a reduction in the necessary width of thelow-doped drift zone in silicon carbide devices compared totheir silicon counterparts result in faster switching speedsand lower switching losses and thus in much more efficientpower devices. High-voltage 4H-silicon carbide diodes have been fabricatedin a newly developed processing sequence, using standardsilicon process equipment. Epitaxial layers grown by chemicalvapor deposition (CVD) on commercial 4H-silicon carbidesubstrates were used as starting material for both mesa-etchedepitaxial and implanted p+n-n+ planar diodes, Schottky diodesand merged pn-Schottky (MPS) diodes, together with additionaltest structures. The device metallization was optimized to givea low contact resistivity on implanted and epitaxial layers anda sufficiently high Schottky barrier with a singlemetallization scheme. Different high-field termination designshave been tested and breakdown voltages of up to 4 kV onimplanted, field-ring terminated diodes were achieved,corresponding to 80% of the critical electric field. A 5kVepitaxial diode design with a forward voltage drop of 3.5V at acurrent density of 100Acm-2 equipped with an implanted junctiontermination extension (JTE) was also fabricated. A new measurement setup was designed and built with thecapability of measuring current-voltage and capacitance-voltagecharacteristics of semiconductor devices at reverse biases upto 10kV. Together with these electrical measurements, theresults of other characterization techniques were used toidentify performance limiting defects in the fabricated siliconcarbide diodes. Increased forward voltage drop of bipolardevices during on-state operation was studied and it was shownthat the stacking faults causing forward degradation arevisible in scanning electron microscopy. With the help ofsynchrotron white-beam X-ray diffraction topographs (SWBXT),electron beam induced current (EBIC) and electroluminescencemeasurements of silicon carbide diodes, the role of screwdislocations as a dominant source of device failure in the formof localized microplasma breakdown was identified. Screwdislocations with and without open core have been found tocause a 20-80% reduction in the critical electric field of4H-silicon carbide diodes, both for low-voltage (150V) andhigh-voltage (~5kV) designs. While micropipes have almost beeneliminated from commercial silicon carbide material,closed-core screw dislocations are still abundant withdensities in the order of 10000cm-2 in state-of-the-art siliconcarbide epitaxial layers.

In this thesis, a novel low-voltage, highly linear and tunable triode transconductor is introduced. The proposed transconductor with new structure is based on constant drain-source voltage method to operate at low-voltage. The proposed transconductor achieves wide linear input range up to 1.5V at 1.8V supply voltage and the total harmonic distortion is -61dB at 0.7Vpp. The design uses TSMC 0.18£gm CMOS technology and supply voltage as low as 1.6V. Moreover, it possesses large transconductance tuning range from 220£gS to 869£gS and also keeps the wide linear input range.

Although Voltage Varying (VV) strategies like Conservation Voltage Reduction (CVR) are widely used by utilities to reduce the overall energy consumption and peak power demand of distribution feeders, it is aberrant among industrial customers. This research proposes a Voltage Varying (VV) strategy for industrial customers that takes into account their complex characteristics and unique set of constraints. Unlike VV strategies for Local Distribution Companies (LDC), those for an industrial customers are far more complex, and require specific c load modelling and process estimation to infer the optimal operating voltage for the industrial load. The proposed VV technique referred to as Voltage Optimization (VO), is a generic and comprehensive framework that seeks to reduce the energy consumption of the industrial load vis-~a-vis the bus voltage. It utilizes a Neural Network (NN) model of the industrial load, trained using historical operating data, to estimate the real power consumption of the load, based on the bus voltage and overall plant process. This load model, is incorporated into the proposed VO model, whose objective is the minimization of the energy drawn from the substation and the switching operations of Load Tap Changers (LTC). The proposed VO framework is tested on load models developed using simulated and real data. Results suggest that the proposed technique can be successfully implemented by industrial customers or plant operators to improve their energy savings, in comparison to existing VV techniques.

Voltage clamp fluorometry (VCF) was first developed in the mid 1990s by Isacoff and his colleagues. In this approach fluorophores are attached to substituted cysteine residues that are engineered by site-directed mutagenesis. Changes in the dielectric environment of the fluorophore report local transitions that are associated with electrically-related and electrically-silent transitions. VCF provides a powerful technique to observe real time reports of ion channel gating conformations. It has proven to be a useful technique because it adds insight that is not available using other techniques. X-ray crystallography studies give a predominantly static picture of the channel, while patch clamping of channels gives information only about residues that effect ionic current flow. Similarly, gating current provides insight only about residues that are charged and move across the membrane electric field. In this thesis we examined the structural rearrangements of the Shaker channel and the effect of 4-AP on channel gating. We also examined for the first time the structural rearrangements of the Kv1.5 gating and the how the channel responds to depolarization pulses. This work is instrumental in the examination of the potassium channel gating.

Serotoninergic type 3 receptors (5HT3Rs) are members of the Cys-loop family of ligand-gated ion channels (LGIC), which includes nicotinic ACh, glycine, GABA-A and GABA-C receptors. All members of this family are widely expressed in the central and peripheral nervous systems, where they mostly participate in fast synaptic transmission. Activation of 5HT3Rs on vagal sensory nerve endings affect respiration, circulation, emesis and nociception; and in the central nervous system they are implicated in anxiety, depression, and drug dependence. In contrast, the function of 5HT3Rs in sympathetic neurons has not been fully determined. We discovered that 5HT3Rs interact with nicotinic acetylcholine receptors (nAChRs), the main drivers of the fast cholinergic autonomic synapse, through cross-talk mechanisms. We examined cross-talk by the patch-clamp technique on cultured mouse superior cervical ganglia (SCG) neurons. Co-stimulation of 5HT3Rs and nAChRs resulted in the generation of a combined current that was smaller than arithmetically predicted if the receptors did not interact with one another. This interaction, which we quantified as mean peak amplitude and mean ionic charge, was dependent on activation of 5HT3Rs and nAChRs, and independent of metabotropic receptors, Ca2+ entry and Ca2+ second messenger pathways, and of the direct action of 5HT on nAChRs. Preliminary data using an antibody targeted to the M3-M4 linker region of the 5HT3A subunit revealed that 5HT3Rs and nAChRs possibly cross-talk through physical interactions. These results revealed a potential role of the 5HT3R in the regulation of sympathetic synaptic transmission through cross-talk inhibition of nAChRs.

This report describes the development of a high-voltage connector at the request of Scandinova Systems AB in Uppsala. The development process is described from the making of a customer demand specification, to the making of drawings for the manufacturing of prototypes. Scandinova develops high-voltage modulators, hence the need for connectors that can handle very large power pulses. Their current connector has several weaknesses that may cause the connector to melt or catch fire. The development began with a number of studies that included the modulator structure and the current connector structure and functions. In addition, to collect Further demands, requests or ideas for the new product a survey were distributed to the staff at Scandinova. All the collected information was summarized in a a customer demand specification. There after a wide variety of concepts were generated. The concepts were then compared, merged, improved, or rejected in order to get a stronger concept. The remaining concepts were then evaluated using a concept selection matrix. In consultation with Scandinovas R & D department it was then decided to further develop four of the concepts in 3D CAD. The selected concepts was then designed in detail and the material selection were made. This was followed by a final evaluation with Scandinova to evaluate the concepts. The evaluation showed that three of the concepts were still interesting. Therefore, drawings were produced for the remaining three concepts, the drawings were there after submitted to Scandinova for prototyping. This report shows that at least one of the concepts seems to be substantially better than Scandinovas current high-voltage connector.

This research suggests a novel voltage control scheme that can compensate for voltage sag and swell conditions in three-phase power systems. Faults occurring in power distribution systems or facilities in plants cause the voltage sag or swell. For sensitive loads, even voltage sags of short duration can cause serious problems in the entire system. In order to mitigate power interruptions, this research proposes a scheme called Voltage Sag Supporter utilizing a PWM (Pulse Width Modulation)-Switched Autotransformer. The proposed scheme is able to quickly recognize the voltage sag or swell condition, and it can correct the voltage by either boosting the input voltage during voltage sag events or reducing the input voltage during voltage swell events. Among existing methods, the scheme based on the inverter system such as dynamic voltage restorers (DVR) require an inverter, a rectifier, and a step-up down transformer, which makes the system expensive. AC converters can be used for the purpose of the research. However, they consist of two solid-state switches per one phase and include energy storage devices such as reactors and capacitors. The switching device for the high voltage application is relatively expensive so that this research suggests a scheme utilizing only one switch for the output voltage control, which makes the system more stable and cost effective. The proposed scheme can be applied at any voltage and provides cost and size advantages over existing methods due to the reduced number of switching components and no need of energy storage devices. Simulations and experiments have been carried out to verify the validity of the proposed scheme, and prototype experiments are being done to confirm the control scheme.

The aim of this thesis is to design a controllable DC-link output voltage for isolated slotless tubular linear generators (STLG), which is capable of directly harnessing wave and solar thermal energies. For supplying stable DC-link voltage to load, a suitable voltage regulation circuit is designed based on the integrate system performance assessment. Electrical and mechanical parameters in this refined STLG design are involved to analyze the operational behaviors through magnetic equivalent circuit analysis at different operating modes. From the theoretical modeling and experimental results, both the AC-side and DC-side properties of generator outputs can then be thoroughly investigated. Finally, based on the performance of controllable rectifier model, a three-phase PWM rectifier has been established, and then the regulated DC-link voltage can be implemented using a DSP-based controller combined with required peripheral circuits.

In previous studies, I learned the curing of the electro-optical effects in polymer stabilize blue phase liquid crystal under different temperature, such as the hysteresis effect, residual transmittance, drive voltage. So find out before curing blue phase temperature range is very important. Since previous studies have used methods is polarizing microscope and measuring reflectance spectra. In order to the blue phase be used in the display. If we use of Bragg reflectors in the visible blue phase liquid crystal. Resulting in the dark state is not good, the contrast reduction, so we must use the blue phase liquid crystal reflectance spectra in the non-visible light. But this liquid crystal cannot use the previously described methods to define the blue phase liquid crystal temperature range. In our experiment, we use different ways to recognized liquid crystal. We have used polarizing microscope, DSC, Kossel diagram and measuring reflectance spectra. We cannot see blue phase by polarizing microscope and Kossel diagram because the blue phase liquid crystal reflectance spectra in the non-visible light. The liquid crystal material absorbs the UV light. Our DSC resolution is not enough to found the blue phase temperature range. When we recognized liquid crystal, we found the light run through the liquid crystal box. In different phase have different lateral scattering intensity. When we cooling temperature can found the lateral scattering intensity is weak in isotropic. When we phase enter the blue phase II, the lateral scattering intensity rise slowly. When the blue phase II into the blue phase I, we can see first decreased and then increased curve. Last when into the cholesterol phase, the lateral scattering intensity rises quickly. We observe this property can discriminate the blue phase temperature range. When we found the blue phase temperature range, we analyze the hysteresis and drive voltage in different curing temperature. We found this material property. When we curing in high temperature. The drive voltage has decrease, but the hysteresis has increase. When curing in low temperature. The drive voltage has increase, but the hysteresis has decrease. Last we use SEM analyze the polymer structure. But we lost the slight polymer structure when we wash the liquid crystal. So we cannot analyze the slight polymer structure.

Since the invention of SRAM (Static Random Access Memory), many improvements have been proposed. The major targets are speed, area, and power consumption. The evolution of the CMOS process technology makes it possible to implement SRAM by using dual threshold voltage transistors. Hence, we will use TSMC (Taiwan Semiconductor Manufacturing Company) 0.25 $mu$m 1P5M CMOS process to realize the dual threshold voltage SRAM in this thesis. In order to reduce SRAM internal power consumption, we also propose quenchers to suppress unwanted oscillation between bit lines. In addition, several types of BIST (Build In Self Test) comparators are also proposed to test the mentioned SRAM. After detailed simulations, the proposed comparators possess impressive results in high fan-in, low transistor count, and high speed. The proposed SRAM and BIST comparators are fabricated by the CMOS process provided by National Science Council Chip Implementation Center (CIC). The measurements of the chips are fully corrected to meet the design goals.