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Measurement of internal current densities during a HiPIMS discharge with a Rogowski coilKarlsson, Magnus January 2011 (has links)
In this study, the current densities in three different directions (r, φ and z) have been measured above the target during a HiPIMS discharge by the use of a Rogowski coil. This was done to examine the key transport parameter Jφ/JD┴ = ωge TEFF throughout the whole measured area, which is a key parameter describing how electrons are transported across magnetic field lines. The coil was adapted to the certain plasma environment that is present during a HiPIMS discharge in consideration due to the extreme environment that is present during the experiment. The thin film deposition system, where the measurements were performed, had a background pressure of ~10-6Torr and during the discharges the chamber were filled with an Ar to the partial pressure of 3mTorr. The previously reported anomalous fast transport of charged particles was verified and the faster-than-Bohm cross-B transport was found to be present in the chamber during the whole discharge but occupying a diminishing area closer to pulse turn off.
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The Optimization and Applications of Magic Angle Spinning Surface Micro-Coil Probes in Nuclear Magnetic ResonanceKe, Wea-len 25 May 2011 (has links)
The most critical problem of NMR spectroscopy and magnetic resonance imaging (MRI) is the relatively low sensitivity compared to other forms of spectroscopy, limiting the applicability of these techniques. Most of the existing research focused on trying to alleviate these problems through hyperpolarization techniques, strong magnetic fields, low temperature experiments (<25K), and pulse sequence development. Going beyond the previously stated methods, researchers found that the implementation of smaller resonant coils is a more convenient and effective way to alleviate the problem of low sensitivity in NMR spectroscopy and magnetic resonance imaging. In this work, a systematic optimization of the parameters for micro-coil probes and magic-angle coil spinning (MACS) probes was carried out with various common NMR nuclear species such as 1H, 31P, 23Na, 79Br on two NMR spectrometers (200 MHz and 500 MHz). The optimized wire diameter, coil diameter, number of turns, the inner and outer diameters of the capillary, the matching capacitors etc have been obtained and demonstrated with a real biological system. In addition, we found that the conventional placement of the sample within the glass tube wrapped by a coil yields a lower signal and sensitivity when compared to coating the sample onto the coil prior to wrapping around the capillary. A new method of performing MACS experiment with micro-coil technology, therefore, was subsequently proposed, namely, micro surface coil magic angle spinning (MISCMAS). The optimized experimental conditions were then determined with both liquid and solid state samples.
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Neural Stimulation¡BRecording and Impedance Measuring Circuitry for Implantable Bio-medical Systems and A Dual-OPA Coil Driver for SOC Heat DissipationFang, Kuan-wen 04 July 2006 (has links)
The first topic of this thesis proposes a neural stimulation, recording and impedance measuring system for implantable applications. It includes a stimulation DAC, a instrumentation amplifier, an ADC, and a digital controller which decides the operation of each block according to the required functions. The function provided by the system include micro-stimulation, neural signal recording, or impedance measurement.
The second topic is to describe a dual-OPA coil driver for SOC heat dissipation. It includes two class AB complementary output drivers which can drive an inductance load, such as micro motors and fans. It also discusses the feasibility of a bipolar transistor in CMOS process.
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Single echo acquisition magnetic resonance imagingMcDougall, Mary Preston 12 April 2006 (has links)
The dramatic improvement in magnetic resonance imaging (MRI) scan time over the past fifteen years through gradient-based methods that sample k-space more efficiently and quickly cannot be sustained, as thresholds regarding hardware and safety limitations are already being approached. Parallel imaging methods (using multiple receiver coils to partially encode k-space) have offered some relief in the efforts and are rapidly becoming the focus of current endeavors to decrease scan time. Ideally, for some applications, phase encoding would be eliminated completely, replaced with array coil encoding instead, and the entire image formed in a single echo.
The primary objective of this work was to explore that acceleration limit  to implement and investigate the methodology of single echo acquisition magnetic resonance imaging (SEA MRI). The initial evaluation of promising array coil designs is described, based on parameters determined by the ability to enable the imaging method. The analyses of field patterns, decoupling, and signal-to-noise ratio (SNR) that led to the final 64-channel array coil design are presented, and the fabrication and testing of coils designed for 4.7T and 1.5T are described. A detailed description of the obtainment of the first SEA images  64xNreadout images, acquired in a single echo  is provided with an evaluation of those images and highly accelerated images (through parallel imaging techniques) based on SNR and artifact power. Finally, the development of methodologies for various MR applications is described: applications that would particularly benefit from the speed of the imaging method, or those to which the method or the tool (array coil) lends itself. These applications include, but are not limited to, 3D imaging (phase encode in the slice select direction), resolution-enhanced imaging, large-scale (field-of-view) microscopy, and conformal surface imaging. Finally, using the primary enablement of the method  the ability to obtain complete MR images at speeds limited only by the time it takes to acquire a single echo  is presented with a discussion of extremely high frame rate imaging.
The contribution to the field of medical imaging is the first implementation, characterization, and demonstration of applications for the acquisition of MR images in a single echo.
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High-precision Position Control of Moving Coil motor and Flexure mechanism Using Quantized Current Regulator and Disturbance ObserverHsieh, Feng 05 January 2010 (has links)
The position control has played an important role in high-tech industries. For example, we hope the control performance fast and precisely in the biomedical industry or high-speed precision machinery. However, the high-precision positioning platform will encounter backlash, friction, hysteresis ... and so on. Therefore, this paper will use the linear voice coil motor to drive single-axis flexure mechanism, to solve the nonlinear problem unnecessarily. Then, the quantized current regulator has been reached by high efficiency robust frequency control and to design with a low-pass filter of the interference within the system parameter estimation to reduce the impact of changes in items, and then by the simulation test analysis showed that the proposed hybrid control method has simultaneous control of voice coil motor current and the flexure mechanism targeting the advantages of location, and the use of traditional pulse-width modulation of the PI current controller with integral type of smooth position control mode, respectively quantized current regulator and the disturbance estimator to do a comparative analysis of simulation . Finally the use analogies full the bridge electric circuit, several logic and the operational amplifier realizes the quantification current regulator.
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Structure - functional relationships of Right handed coiled-coil (RHCC) from the Archaea, Staphylothermus marinusOgbomo, Efehi Kelly 10 September 2010 (has links)
Hyperthermophilic proteins are of great interest in both the academic and industrial world in understanding how these proteins are capable of retaining their biological activity under such harsh environmental conditions. This thesis studies a tetrabrachion stalk domain from Staphylothermus marinus, know as Right Handed Coiled Coil (RHCC). This protein is of interest due to its extreme thermostability and its affinity for heavy metals. We aim to better understand the reason for the extreme thermal stability of the protein and to take advantage of the proteins affinity for heavy metals with a view to developing a novel approach to bioremediate Hg2+, a major environmental pollutant. Our results clearly indicated that the protein is more thermostable in alkaline conditions in comparison to acidic conditions. This observation can be explained by careful inspection of the high resolution structure. Our data also clearly show that RHCC is able to bind ionic mercury compounds such as mercury nitrate and dipotassium mercury iodide.
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Heat Transfer of a Multiple Helical Coil Heat Exchanger Using a Microencapsulated Phase Change Material SlurryGaskill, Travis 2011 December 1900 (has links)
The present study has focused on the use of coil heat exchangers (CHEs) with microencapsulated phase change material (MPCM) slurries to understand if CHEs can yield greater rates of heat transfer. An experimental study was conducted using a counterflow CHE consisting of 3 helical coils. Two separate tests were conducted, one where water was used as heat transfer fluid (HTF) on the coil and shell sides, respectively; while the second one made use of MPCM slurry and water on the coil and shell sides, respectively. The NTU-effectiveness relationship of the CHE when MPCM fluid is used approaches that of a heat exchanger with a heat capacity ratio of zero. The heat transfer results have shown that when using a MPCM slurry, an increase in heat transfer rate can be obtained when compared to heat transfer results obtained using straight heat transfer sections. It has been concluded that the increased specific heat of the slurry as well as the fluid dynamics in helical coil pipes are the main contributors to the increased heat transfer.
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Structure - functional relationships of Right handed coiled-coil (RHCC) from the Archaea, Staphylothermus marinusOgbomo, Efehi Kelly 10 September 2010 (has links)
Hyperthermophilic proteins are of great interest in both the academic and industrial world in understanding how these proteins are capable of retaining their biological activity under such harsh environmental conditions. This thesis studies a tetrabrachion stalk domain from Staphylothermus marinus, know as Right Handed Coiled Coil (RHCC). This protein is of interest due to its extreme thermostability and its affinity for heavy metals. We aim to better understand the reason for the extreme thermal stability of the protein and to take advantage of the proteins affinity for heavy metals with a view to developing a novel approach to bioremediate Hg2+, a major environmental pollutant. Our results clearly indicated that the protein is more thermostable in alkaline conditions in comparison to acidic conditions. This observation can be explained by careful inspection of the high resolution structure. Our data also clearly show that RHCC is able to bind ionic mercury compounds such as mercury nitrate and dipotassium mercury iodide.
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Characterization of the Dynein-Dynactin InteractionFindeisen, Peggy 01 August 2014 (has links)
No description available.
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Die a-Untereinheiten von Ionenkanälen assemblieren durch eine Tetramerisierung von Coiled-CoilsJenke, Marc. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2003--Frankfurt (Main).
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