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An Investigation of a Novel Monolithic Chromatography Column, Silica Colloidal Crystal Packed ColumnsMalkin, Douglas Scott, Malkin, Douglas Scott January 2010 (has links)
Many researchers have investigated ways to improve the separation power of conventional chromatography, most notable is the development of ultra-high performance liquid chromatography (UHPLC). However, only slight improvements in separation efficiency have been achieved up to this point, and unfortunately, modern reversed phase liquid chromatography (RPLC) methods do not have high enough resolving power to analyze complex proteomic mixtures.Uniformly sized silica particles from 10 nm to 1 micron are known to self-assemble into a highly ordered face centered cubic crystal. Silica colloidal crystals have shown recent promise in biological applications such as permselective nanoporous membranes, DNA sieving, reversed phase separation of small molecules on planar substrates, protein sieving, microarrays, total internal reflection fluorescence microscopy of live cells, and 3-D scaffolds for supported lipid films. In this work, silica colloidal crystals packed in capillaries are explored for their potential improvement in the efficiency of reversed phase chromatography.The silica colloidal crystal columns were chemically stabilized by with trichlorosilanes. The trichlorosilanes form chemical bonds between the particles and the particles and the substrate creating an increase in mechanical stability, and at the same time, providing an excellent chromatographic monolayer. After stabilization the fritless columns were able to withstand the pressure limit of the commercial UHPLC. Next, the columns were characterized using a small dye molecule, 1,1' - Didodecyl - 3,3,3',3' - tetramethylindocarbocyanine (DiIC12). The dye was run under capillary electrochromatography (CEC), and sub-micron plate heights were achieved. Further, a van Deemter plot of the dye molecule indicates that the plate height is largely due to the molecule's diffusion. This result suggests that the plate heights for proteins would be even smaller, since proteins have diffusion coefficients an order of magnitude smaller. The analysis of proteins by CEC yielded nanometer plate heights. Finally, pressure driven flow separations coupled with nano-electrospray ionization (n-ESI) MS have also been explored. The Poiseuille flow profile has been shown not to perturb the low plate heights. Gradient elution of peptides was also achieved, and the results demonstrate the highest chromatographic peak capacities for short analysis times to date.
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High Efficiency Two-Stage GaN Power Amplifier with Improved LinearityKhan, Amreen January 2013 (has links)
The trade-off between linearity and efficiency is the key limiting factor to wideband power amplifier design. Current wireless research focuses much of its effort on building power amplifiers with the two aforementioned criteria going hand in hand to build an optimal design.
This thesis investigates the sources of nonlinearity associated with GaN high electron mobility transistors (HEMT), and their subsequent effects on the linearity metrics of the power amplifier. The investigation began with an analysis of the sources of nonlinearity, and then a design-based approach to mitigate those sources of nonlinearity was developed. This design approach was compared with existing trends in power amplifier design. The device technology used in the design was CREE GaN HEMT (45W and 6W).
In this report, a systematic approach to designing a two stage power amplifier is discussed, and analyzed for design of linear and highly efficient power amplifiers for base stations. The designed power amplifier consists of two stages: a driver stage and a power stage. The driver stage aimed to linearize the power stage by using circuit analysis and transistor properties along with providing the necessary gain. The power stage was built to complement the driver stage and to achieve high efficiency for the power amplifier. An inter-stage matching network placed between the two stages allowed for the required matching of impedances; transmission lines in the bias feed controlled the harmonic impedances for optimal performance without disrupting performance at fundamental frequencies. This approach effectively improved, and maintained, high efficiency over 200MHz of bandwidth.
The design approach was simulated and fabricated in order to test the feasibility of linear power amplifier operation with the use of digital pre-distortion (DPD). The fabricated prototype achieved about 70% peak efficiency over the bandwidth and maintained linearity above 40dBc adjacent channel leakage ratio (ACLR) and below 3% error vector magnitude (EVM). The measurement results indicated that the need for DPD was eliminated when the power amplifier was operating in back-off at the center frequency (800MHz). This thesis compares the prototyped design with existing multistage designs which use linear drivers. The report provides conclusions derive from measurement results and bandwidth limitations faced throughout the course of the design. Lastly, potential research directions, which may allow researchers to overcome the limitations of this design, are discussed.
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Design of High Efficiency Broadband Adjusted Class AB Power AmplifierVatankhahghadim, Aynaz January 2010 (has links)
This thesis starts with a discussion of different classes of operation of power amplifiers (PAs). Comparing advantages and disadvantages of these classes, class AB is chosen as the best initial candidate for the design of broadband PA.
Different methods for design of matching networks are first discussed. Some of them fall into the group of narrowband matching networks, while others are suitable for a broadband context. Broadband design methodologies are categorized into two groups of real-to-real transformations and complex-to-real transformations. Complex-to-real transformations are the most useful methods for this project, since design of power amplifiers deals with complex loads rather than just real loads.
The design of broadband matching networks exploiting filter theory is presented in this thesis for synthesizing broadband and highly efficient power amplifiers (PAs). Starting with sets of optimum impedances over the targeted frequency band, the matching networks are designed using a systematic approach.
The effects of load termination at the 2nd and 3rd harmonic on the PA performance (efficiency) are studied. The significance of proper termination, especially at the 2nd harmonic, is highlighted. To prevent further complication of the design process, though, specific harmonic termination (stubs) is avoided and special arrangement of the matching network (position of the bias network) is preferred, as it is found to lead to acceptable efficiency.
Two PA prototypes were designed with the proposed methodology using 25W GaN devices. The designs targeted two frequency bands: 1.8 to 2.2 GHz (20% BW) and 1.8 to 2.7 GHz (40% BW). For the former, drain efficiency (DE) of 70% (+/–5%) and output power of 45.5 dBm (+/- 1.0dB) was measured while the latter achieved very promising efficiency of about 60% over the entire bandwidth.
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A High Efficiency Switched-Capacitor DC-DC up ConverterYang, Shun-Pin 25 July 2003 (has links)
A new DC-DC up converter with high efficiency and low output ripple is proposed. We replace previous charge pump converters by switched-capacitor converters to improve the power efficiency and add a voltage regulator at the output to reduce the ripple voltage. The converter reduces the magnitude of output voltage ripples to 36% of the previous converter, and improves the power efficiency from 58% to 73%. The proposed converter is designed to obtain 1.6 mA driving capability with a output voltage around 5.3 ~ 5.4 V. A VCO is also added as the load to test the converter circuit. The VCO is insensititive to power supply noises. The proposed converter circuit is simulated in a TSMC 0.35-um Mixed-mode (2P4M) CMOS process.
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The study of an open innovation model for the industrial chain of electrical steelTsai, Song-jau 18 July 2009 (has links)
Resources limitation in corporation renders the need for open innovation to advance their competence. Open innovation suggests utilization of outside resources can improve internal innovation and the internal IP¡¦s shall extend their usage beyond the boundary of firm to reach maximum benefit. The most remarkable open innovation paradigm in the history was IBM¡¦s release of its PC core software to give impetus to information revolution. Recently, Proctor and Gamble adapts the open innovation model and seek for external ideas which account for more than 50% of innovation of the company. Despite its phenomenal success in several cases, open innovation is not rooted in many industries. This study would investigate on the feasibility of the application of open innovation model to the electrical steel (ES) industry chain.
Electrical steel is one of the most dedicated products in the steel industry. It¡¦s the crucial material in motors and transformers. China Steel holds more than 7% of the market share of ES of the world and influences the local motor markets greatly. Taiwan was once recognized the most important manufacturing base of small motors in the world. Nevertheless, motor industries in Taiwan have suffered huge decline in the past 20 years due to migrating to China whose economy reform provides much more attractive investment environment by lower wages and other operation costs. Until recently, soaring energy prices and tighter environment protection measures recently create growing worldwide need of high efficiency motors and provide new opportunity for the motor industry in Taiwan. Being the sole supplier of high quality ES in Taiwan, how China Steel takes advantage of this opportunity and enhances its competiveness is the main interest of this study.
This study focuses on the industry chain of ES in Taiwan by systematic survey on its market, technology, and man power to understand its strength, weakness, facing threat and opportunity. An open innovation model is proposed and implemented in the ES industry chain by establishing a new platform, introducing new management paradigm and creating new efficacy indices. The model potentially allows continuous technology support to the chain and creates a sustainable business environment. Its feasibility is further discussed as to forming a healthy industry chain.
The fast growing trend of global production volume of ES indicates the ever-increasing demand in the motor industry. The consumption rate of ES in Taiwan however did not appear the same order of growing rate as the rest of the world. This may imply the motor industry in Taiwan still faces tough challenge from China. Advancing and upgrading in design and analytical capability along with the competitive manufacturing bandwidth is the only solution to regain the competiveness. The proposed open innovation model is anticipated to promote the value of the ES industry chain, which in turn will increase China Steel¡¦s domestic market share for high quality ES.
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Design of High Efficiency Broadband Adjusted Class AB Power AmplifierVatankhahghadim, Aynaz January 2010 (has links)
This thesis starts with a discussion of different classes of operation of power amplifiers (PAs). Comparing advantages and disadvantages of these classes, class AB is chosen as the best initial candidate for the design of broadband PA.
Different methods for design of matching networks are first discussed. Some of them fall into the group of narrowband matching networks, while others are suitable for a broadband context. Broadband design methodologies are categorized into two groups of real-to-real transformations and complex-to-real transformations. Complex-to-real transformations are the most useful methods for this project, since design of power amplifiers deals with complex loads rather than just real loads.
The design of broadband matching networks exploiting filter theory is presented in this thesis for synthesizing broadband and highly efficient power amplifiers (PAs). Starting with sets of optimum impedances over the targeted frequency band, the matching networks are designed using a systematic approach.
The effects of load termination at the 2nd and 3rd harmonic on the PA performance (efficiency) are studied. The significance of proper termination, especially at the 2nd harmonic, is highlighted. To prevent further complication of the design process, though, specific harmonic termination (stubs) is avoided and special arrangement of the matching network (position of the bias network) is preferred, as it is found to lead to acceptable efficiency.
Two PA prototypes were designed with the proposed methodology using 25W GaN devices. The designs targeted two frequency bands: 1.8 to 2.2 GHz (20% BW) and 1.8 to 2.7 GHz (40% BW). For the former, drain efficiency (DE) of 70% (+/–5%) and output power of 45.5 dBm (+/- 1.0dB) was measured while the latter achieved very promising efficiency of about 60% over the entire bandwidth.
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High Efficiency Two-Stage GaN Power Amplifier with Improved LinearityKhan, Amreen January 2013 (has links)
The trade-off between linearity and efficiency is the key limiting factor to wideband power amplifier design. Current wireless research focuses much of its effort on building power amplifiers with the two aforementioned criteria going hand in hand to build an optimal design.
This thesis investigates the sources of nonlinearity associated with GaN high electron mobility transistors (HEMT), and their subsequent effects on the linearity metrics of the power amplifier. The investigation began with an analysis of the sources of nonlinearity, and then a design-based approach to mitigate those sources of nonlinearity was developed. This design approach was compared with existing trends in power amplifier design. The device technology used in the design was CREE GaN HEMT (45W and 6W).
In this report, a systematic approach to designing a two stage power amplifier is discussed, and analyzed for design of linear and highly efficient power amplifiers for base stations. The designed power amplifier consists of two stages: a driver stage and a power stage. The driver stage aimed to linearize the power stage by using circuit analysis and transistor properties along with providing the necessary gain. The power stage was built to complement the driver stage and to achieve high efficiency for the power amplifier. An inter-stage matching network placed between the two stages allowed for the required matching of impedances; transmission lines in the bias feed controlled the harmonic impedances for optimal performance without disrupting performance at fundamental frequencies. This approach effectively improved, and maintained, high efficiency over 200MHz of bandwidth.
The design approach was simulated and fabricated in order to test the feasibility of linear power amplifier operation with the use of digital pre-distortion (DPD). The fabricated prototype achieved about 70% peak efficiency over the bandwidth and maintained linearity above 40dBc adjacent channel leakage ratio (ACLR) and below 3% error vector magnitude (EVM). The measurement results indicated that the need for DPD was eliminated when the power amplifier was operating in back-off at the center frequency (800MHz). This thesis compares the prototyped design with existing multistage designs which use linear drivers. The report provides conclusions derive from measurement results and bandwidth limitations faced throughout the course of the design. Lastly, potential research directions, which may allow researchers to overcome the limitations of this design, are discussed.
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Characterization and Performance Analysis of High Efficiency Solar Cells and Concentrating Photovoltaic SystemsYandt, Mark 11 January 2012 (has links)
As part of the SUNRISE project (Semiconductors Using Nanostructures for Record Increases in Solar-cell Efficiency), high efficiency, III-V semiconductor, quantum-dot-enhanced, triple-junction solar cells designed and manufactured by Cyrium Technologies Inc. were integrated into OPEL Solar, MK-I, Fresnel-lens-based, 550x concentrating modules carried on a dual axis tracker.
Over its first year of operation 1.8 MWh of AC electrical energy was exported to the grid. Measurements of the direct and indirect components of the insolation, as well as the spectral irradiance of light incident on the demonstrator in Ottawa, Canada are presented. The system efficiency is measured and compared to that predicted by a system model to identify loss mechanisms so that they can be minimized in future deployments.
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Surface Passivation of Crystalline Silicon by Dual Layer Amorphous Silicon FilmsStepanov, Dmitri 25 August 2011 (has links)
The probability of recombination of photogenerated electron hole pairs in crystalline silicon is governed by the density of surface defect states and the density of charge carriers. Depositions of intrinsic hydrogenated amorphous silicon (a-Si:H) in dc saddle field (DCSF) PECVD system and hydrogenated amorphous silicon nitride (SiNx) in rf PECVD system forms a dual layer stack on c-Si, which results in an excellent passivation of the surface and an anti-reflection coating.
Response Surface Methodology is used in this work to optimize the deposition conditions of SiNx. Optimization of the response surface function yielded deposition conditions that materialized in a surface recombination velocity of less than 4cm/s.
The BACH (Back Amorphous Crystalline silicon Heterojunction) cell concept makes use of this dual layer a-Si:H/SiNx stack to form a high efficiency photovoltaic device. The high quality passivating structure can result in the BACH solar cell device with more than 20% conversion efficiency.
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Surface Passivation of Crystalline Silicon by Dual Layer Amorphous Silicon FilmsStepanov, Dmitri 25 August 2011 (has links)
The probability of recombination of photogenerated electron hole pairs in crystalline silicon is governed by the density of surface defect states and the density of charge carriers. Depositions of intrinsic hydrogenated amorphous silicon (a-Si:H) in dc saddle field (DCSF) PECVD system and hydrogenated amorphous silicon nitride (SiNx) in rf PECVD system forms a dual layer stack on c-Si, which results in an excellent passivation of the surface and an anti-reflection coating.
Response Surface Methodology is used in this work to optimize the deposition conditions of SiNx. Optimization of the response surface function yielded deposition conditions that materialized in a surface recombination velocity of less than 4cm/s.
The BACH (Back Amorphous Crystalline silicon Heterojunction) cell concept makes use of this dual layer a-Si:H/SiNx stack to form a high efficiency photovoltaic device. The high quality passivating structure can result in the BACH solar cell device with more than 20% conversion efficiency.
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