This thesis analyses the effect spin-orbit coupling has on the dispersion of Langmuir waves in magnetized plasmas, using recently developed kinetic theories of plasmas including quantummechanical and relativistic effects. Two new wave modes appearclose to the resonance <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5CDelta%20%5Comega_%7Bc%7D" /> = ( g/2 − 1)<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Comega_%7Bc%7D" /> , where <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Comega_%7Bc%7D" /> is the cyclotron frequency and g is the electron gyromagnetic ratio. Forconsidered long wave lengths the deviation from this resonanceis very small. The wave modes are also very weakly damped.

This research focuses on the development of engineered materials, also known as meta- materials, with desirable effective constitutive parameters: electric permittivity (epsilon) and magnetic permeability (mu) to decouple antennas and noise mitigation from electromagnetic systems. An interesting phenomenon of strong relevance to a wide range of problems, where electromagnetic interference is of concern, is the elimination of propagation when one of the constitutive parameters is negative. In such a scenario, transmission of electromagnetic energy would cease, and hence the coupling between radiating systems is reduced. In the first part of this dissertation, novel electromagnetic artificial media have been developed to alleviate the problem of mutual coupling between high-profile and ow-profile antenna systems. The developed design configurations are numerically simulated, and experimentally validated. In the mutual coupling problem between high-profile antennas, a decoupling layer based on artificial magnetic materials (AMM) has been developed and placed between highly-coupled monopole antenna elements spaced by less than Lambda/6, where Lambda is the operating wavelength of the radiating elements. The decoupling layer not only provides high mutual coupling suppression (more than 20-dB) but also maintains good impedance matching and low correlation between the antenna elements suitable for use in Multiple-Input Multiple-Output (MIMO) communication systems. In the mutual coupling problem between low-profile antennas, novel sub-wavelength complementary split-ring resonators (CSRRs) are developed to decouple microstrip patch antenna elements. The proposed design con figuration has the advantage of low-cost production and maintaining the pro file of the antenna system unchanged without the need for extra layers. Using the designed structure, a 10-dB reduction in the mutual coupling between two patch antennas has been achieved. The second part of this dissertation utilizes electromagnetic artificial media for noise mitigation and reduction of undesirable electromagnetic radiation from high-speed printed-circuit boards (PCBs) and modern electronic enclosures with openings (apertures). Numerical results based on the developed design configurations are presented, discussed, and compared with measurements. To alleviate the problem of simultaneous switching noise (SSN) in high-speed microprocessors and personal computers, a novel technique based on cascaded CSRRs has been proposed. The proposed design has achieved a wideband suppression of SSN and maintained a robust signal integrity performance. A novel use of electromagnetic bandgap (EBG) structures has been proposed to mitigate undesirable electromagnetic radiation from enclosures with openings. By using ribbon of EBG surfaces, a significant suppression of electromagnetic radiation from openings has been achieved.

Loosely coupled workgroups are common in the real world, and workers in these groups are autonomous and weakly interdependent. They have patterns of work and collaboration that distinguish them from other types of groups, and groupware systems that are designed to support loose coupling must address these differences. However, they have not been studied in detail in Computer-Supported Cooperative Work (CSCW), and the design process for these groups is currently underspecified. This forces designers to start from scratch each time they develop a system for loosely coupled groups, and they must approach new work settings with little information about how work practices are organized. <br><br> In this dissertation, I present a design framework to improve the groupware design process for loosely coupled workgroups. The framework has three main parts that add a new layer of support to each of the three stages in the general groupware design process: data collection about the target work setting, analysis of the data, and system design based on the analysis results. The framework was developed to provide designers with support during each of these stages so that they can consider important characteristics of loosely coupled work practice while carrying out design for the target group. The design framework is based on information from CSCW and organizational research, and on real-world design experiences with one type of loosely coupled workgrouphome care treatment teams. <br><br> The framework was evaluated using observations, interviews, and field trials that were carried out with multidisciplinary home care treatment teams in Saskatoon Health Region. A series of field observations and interviews were carried out with team members from each of the home care disciplines. The framework was then used to develop Mohoc, a groupware system that supports work in home care. Two field trials were carried out where the system was used by teams to support their daily activities. Results were analyzed to determine how well each part of the design framework performed in the design process. The results suggest that the framework was able to fill its role in specializing the general CSCW design process for loosely coupled groups by adding consideration for work and collaboration patterns that are seen in loosely coupled settings. However, further research is needed to determine whether these findings generalize to other loosely coupled workgroups.

The objective of this research is to investigate low-complexity, efficient electronic equalizers to increase the data rate and possibly extend the reach of multi-mode fiber (MMF) links. Specifically, we begin by baselining the performance limits of conventional receivers. A robust, in-house mode solver was developed as part of this research and is currently being used by one of the largest fiber manufacturers in their internal R &D work. A detailed performance assessment of the impact of decision feedback equalizers has been conducted using an extensive model of the installed fiber base. The finite-length DFE results were instrumental in influencing the IEEE 802.3aq standardization effort. In particular, we were able to achieve a reach of 220m but the original goal of 300m was unattainable on 99% of the installed fiber base using DFEs of moderate complexity. A low-cost equalizer that has excellent performance, the bi-directional DFE, was applied to the MMF channel for the first time. The performance of the infinite-length BiDFE was characterized without any constraints on the signal-to-noise ratio and on the receiver front-end, as has been previously done in the literature. A new joint optimization technique that helps the finite-length BiDFE perform significantly better than the infinite-length DFE was developed. It was shown that given a finite number of filter coefficients, the BiDFE utilizes them better than the conventional DFE. Furthermore, a reach of 350-400m at a data rate of 10 Gbps was shown to be feasible with equalizers of complexity similar to that currently available. A multiple-input, multiple-output (MIMO) characterization of the MMF channel was developed through the simultaneous use of both center and offset launch together with the two-segment photo-detector. The potential benefit of MIMO processing for MMF links was demonstrated by computing Shannon capacity bounds. It was established that the 2x2 MIMO channel performs about 1.4 dBo better than the conventional 1x1 link at 10 Gbps with practical joint launch. The MIMO scheme still has a performance improvement of 1dBo at 20 Gbps thereby indicating that 20 Gbps transmission is feasible. Performance evaluation of multi-km MMF links was conducted using a comprehensive model that accounts for mode coupling effects. It was determined that ignoring mode coupling can result in under-estimation of the optimum DFE penalty by as much as 1~dBo for 1km links.

A study of double-variable-curvature microlenses (DVCM) for promoting coupling efficiency between the high-power 980-nm laser diodes and the single-mode fibers has been proposed. The purpose of the fiber microlens fabrication was to make the mode field match between the laser beam and the fiber as the beam propagating through the fiber microlens. To make the mode match, the shapes of the fiber microlens demanded nothing else but the offset and the curvature radii in minor and major axes. The double-variable-curvature fiber endface (DVCFE) was manufactured through a single-step fully automation grinding process and had less average offset of 0.3£gm, consequently. The radii of curvature in minor and major axis were controlled as an average of 1.2£gm and 33.6£gm, respectively. In the fusing procedure, the slight arc fusion was mainly applied for fine polishing merely instead of reshaping for the reason that the fabricated DVCFE was very close to the ideal shape. Hence, the fabrication time was reduced and the yield was promoted due to the withdrawn step of tip elimination. Furthermore, while the fusion parameters were set to be: fusing distance: 10£gm, arc intensity: 3bits, and fusing time: 200ms in the slight fusion process, the offset was reduced to 0.2£gm due to the shape constraint and surface tension of the DVCFE. And the radii of curvature increased 1.7£gm to 2.9£gm in the minor axis and increased 4.5£gm to 38.1£gm in the major axis, respectively. Owing to the controls of the fully automated grinding procedure and the omission of the tip elimination, the coupling efficiency and yield were improved. As a result, in the experiment, the average and maximum coupling efficiency of 83% and 88% were demonstrated, respectively. And the coupling efficiencies of the 20 samples were higher than 80%. In other words, the proposed DVCM structure of this study was a high coupling efficiency, a high yield output, and reproducible and fully automated single-step grinding process.

We reconstruct 2D simulation to 3D scene and integrated a fluid-solid coupling based on FLO-2D model. Furthermore we add the friction and bump. From the point of view of fluid-solid coupling, we using the flow resistance and yield stress our proposed method make the fluid behaviour and runout more realistic comparing to other fluid-solid coupling research. Besides, from the point of view of debris flow simulation, we integrate the fluid-solid coupling into the debris flow simulation. And we can handle the bump of debris flow regarding trees, stone or house compared with other debris flow simulation.

We have investigated the polarization effect of optical process in the vertically coupled InGaAs quantum dots (QDs) triple layers by varying the thickness of GaAs spacer layer. The TE/TM ratio for the ground state emission decreases from near 4 to 1.5 as the spacer thickness (d) decreases from 40 nm to 5 nm. And, the TE polarization (in-plane polarization) is anisotropic with a stronger component along [01-1] direction. P-type modulation doping further decreases the TE/TM ratio to r = 1.2 for the strong vertical coupling QDs structure of 5-nm spacer. Then, using a cross-sectional transmission electron microscopy directly reveals the InGaAs QDs of 5-nm spacer well aligned along the growth direction. From the electroluminescence (EL) and differential absorption (£G£\) experiments, the higher optical gain and absorption change for the excited state suggest that the e2-hh transition has higher oscillator strength for the vertically coupled QDs. We also investigate for the triple-layer InGaAs vertically coupled quantum dots (VCQDs) by adding modulation doping (MD) in the 5-nm GaAs spacer layers. In addition to the QDs fundamental and excited transitions, a coupled-state transition is observed for the VCQDs. For the VCQDs of p-type MD, the optical transitions at ground state and coupled state are enhanced by the improvement of hole capture for the valence subbands. For the VCQDs of n-type MD, the main absorption change occurs at the coupled state, consistent with the dominant emission peak observed in EL spectra. For GaAs-based solar cells application, in order to enhance absorption at infrared range for GaAs-based solar cells, multi-stack InGaAs VCQDs of 5-nm GaAs spacers are grown in the active region. Due to the strong vertical coupling between QDs would promote quantum efficiency. We have investigated the photovoltaic response for the solar cells by increasing the layer numbers of VCQDs. The device of nine-layer InGaAs VCQDs shows an enhanced short-circuit current density (Jsc) of 10.5 mA/cm2. The value is increased by 42% compared to GaAs reference device. However, the open-circuit voltage (Voc) is reduced from 0.88 V to 0.54 V. Then, we change the GaAs spacer thickness of coupled In0.75Ga0.25As QDs, and investigated the effects on photovoltaic response. For the sample of d =10 nm shows the best performance of current density (Jsc~24 mA/cm2) and efficiency (h~10.6%). The Jsc and h are increases by 55% and 112% more than the device without QDs, respectively.

The thesis can be divided into two chapters: synthesis and application. The first chapter presents the basis of synthesis. Generally, electronic-deficient aromatic molecules require activation before reacting with metal reagents and then can go coupling reaction. Our lab has developed a new bipyridine coupling method without pre-functionalization of pyridines to the corresponding activated halide or metal forms or using of transition metal catalysts. This new method is quite efficient and advantageous for environmental protection. In second chapter, we synthesized 3,3¡¦-dihydroxy-2,2¡¦-bipyridine -based molecules and the functional groups were modified to investigate its liquid crystal properties. According to analyzing data of differential scanning calorimetry (DSC), polarized optical microscope (POM) and powder x-ray diffraction (XRD), we found that a-3 may possess cubic mesophaes with Im3m symmetry, and a series of d-1~d-3 compounds exhibit mesophase and may be further identified as smectic phase.

This study is to improve the coupling efficiency between 980nm high-power pump laser diode and single-mode fiber. In this study, we use the third generation of fiber grinding machine which is designed by Cheng Shiu University, professor Ying-Chien Tsai. This machine is fully automatic. we use it to fabricate the hyperbola microlenses. The advantages about hyperbola microlenses structure are a single-step fabrication, grinding steps to simplify, reduce the grinding time and will greatly reduce the offset of fiber. In the fusing procedure, the slight arc fusion was mainly applied for fine polishing merely instead of reshaping for the reason that the fabricated hyperbola fiber endface was very close to the ideal shape. The fabrication reproducibility and yield increase, and can reduce the cost of grinding. The fiber end shape is similar to the math on the hyperboloid, and the length of the axis of the hyperboloid profile shows a hyperbola. By mathematical properties of hyperbola, we derivation the parameter of radius of curvature for hyperbola microlenses. The definition of the radius of curvature of the hyperbolic vertex and the mode field diameter (the MFD) = 4.2£gm point of intersection with the hyperbola, the characteristics of the formation of this three o'clock round the curvature is the radius of curvature we have said. The radius of curvature (R) is a semi-consistent axial length (a) and two progressive line angle (£c) function, it means we can through the control of ¡§a¡¨ and £c to control the R, but £c is fixed after grinding process. So we choose control parameter ¡§a¡¨ by fusing process, via control ¡§a¡¨ to achieve the purpose of the control R. By various fusing parameters to adjust the gain of ¡§a¡¨, we can control the R in an ideal 2.6-2.8£gm. This process indeed improves the coupling efficiency. This method gives a low offset of the fiber it easier for more than 80%. And larger offset of the fiber by this method can achieve to 70% even 80%.

Much of the current research in magnetic resonance engineering focuses on reducing the acquisition time for obtaining an image while simultaneously maximizing the Signal to Noise ratio (SNR) of the image. It is known that improvement in imaging time or resolution is obtained at the cost of SNR. Therefore wherever possible, RF coil engineers design the coil in such a manner so as to maximize SNR for that coil design. In one such design consideration, most coil designers prefer placing low impedance preamplifiers near the coil. The further the pre-amplifiers are from the coil, the greater will be the signal loss due to transmission and higher will be its input impedance as perceived at the coil which would degrade inter-coil isolation. Owing to the current trend of using increasing number of receiver channels (32, 64 or 128) for parallel imaging, placing the preamplifiers near the coil would greatly complicate the coil construction. The primary objective of this research was to find the relation between SNR and referred preamp impedance and whether preamps need to be placed on the coil, or if they can be placed outside the magnet at the end of a transmission line which would simplify the construction of large count array. In addition, SNR was studied as a function of coil design parameters - coil loading, array coil separation, and system frequency. Both theoretical and experimental methods were used to undertake this investigation. A popular electromagnetic modeling technique, finite difference time domain (FDTD), was used to model SNR in arrays of two 3 inch loop coils at 3T and 1.5T. Results were also verified through bench measurement at 3T and 1.5T and by evaluating SNR. To verify the robustness of our results and to assess the possibility of using low cost standard 50 ohm preamps, we carried out additional bench measurements at 4.7T. Results demonstrated that preamplifier placement is critical at low field strength. At higher field strength, SNR degradation due to preamplifier placement was less owing to heavier coil loading.