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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
471

Theoretical and Numerical Studies of the Air Damping of Micro-Resonators in the Non-Continuum Regime

Hutcherson, Sarne Makel 03 December 2004 (has links)
Micromechanical resonators are used in a variety of sensing and filtering applications. In these applications, the accurate performance of micro resonators depends on the sensitivity of these devices to a particular resonance frequency. This sensitivity is measured using the quality factor Q, which is the ratio of the total input energy into the device to the energy dissipated within a vibration cycle. A higher quality factor indicates a smaller resonance bandwidth, which makes the micro-resonator more effective in identifying a desired signal. Higher Q values result from reductions in dissipation losses. Dissipation losses occur through damping by the ambient fluid, anchor losses, thermoelastic damping, and other sources. The squeeze-film effect is of particular interest in micro-resonators as the fluid enclosed between the resonating components can provide significant dissipation. This work covers investigations into the air damping of oscillating micromachined resonators that operate near a fixed wall, which is parallel to the oscillating surface. The main portion of this work focuses on the theoretical and numerical investigation of the air damping of micromachined resonators when the surrounding gas (air) is in the Free-Molecule regime. Errors and limitations of previous theoretical models have been found and corrected. A molecular dynamics simulation code that is suitable to handle a more general class of resonators has been developed. This code has been used to find the quality factor of a microbeam resonator. The results from the code were compared to existing experimental results, and were found to have very good agreement in the free molecular regime. The simulation was then used to investigate the effects of the oscillation mechanics on the energy dissipation and quality factor. The second part of this work focuses on the region between the bottom surface of a laterally-oscillating disk resonator and the substrate. The compressibility effects of a 1 micron thick film of air on a laterally-oscillating disk resonator were investigated. The pressure perturbation for this case was found to be minimal, which means that the compressibility effects of the fluid film will negligible.
472

Analyzing and classifying the jumping spider of Eugaria albidentata

Lin, Shih-hua 28 July 2010 (has links)
Under the mechanism of natural selection, creatures are forced to evolve naturally in order to survive. Keen-sighted jumping spiders have long been considered as the main predation pressure of terrestrial arthropod. Many species benefit from mimicking the appearance of jumping spider. In this study according to the experimental data from Wang (2009b), a data analysis is undertaken concerning male Ptocasius strupifer¡¦s behavior to different subject groups, namely, male Ptocasius strupifer, female Ptocasius strupifer, male Plexippus paykulli, female Plexippus paykulli, Cataclysta angulata and Eugauria albidentata, so as to investigate the jumping spider mimicry of Eugauria albidentata. In this work, our interest is to compare the behavior of male Ptocasius strupifer on Eugauria albidentata with there of the other five groups mentioned above, and identify which one is the most similar to there of Eugauria albidentata . We use different statistical methods, i.e. likelihood ratio test, factor analysis and cluster analysis to evaluate the closeness of the behavior between different groups. According to the analysis result, it shows that the behavior of Ptocasius strupifer towards Eugauria albidentata is more similar to those of both female Ptocasius strupifer and female Plexippus paykulli. Moreover there is a wide discrepancy between Eugauria albidentata and Cataclysta angulata, although both of them belong to Musotiminae.
473

The Growth Mechanism of Inclined AlN Films and Fabrication of Dual Mode Solidly Mounted Resonators

Chen, Cheng-ting 02 August 2010 (has links)
The 1/4£f dual-mode resonators made from c-axis-oriented aluminum nitride films grown on different conduction material have been studied in this thesis. The RF/DC sputter system is used to grow on layers of reflector. During the porcess, 3.5 pairs of Bragg reflector alternating with W and SiO2 are composed by Si substractor. To achieve 0.999 reflective rate, fabrication parameters are adjusted to make W films become £\-phase structurre. On the other hand, piezoelectric layers as well as reflective layers that using reactive RF magnetron sputtering system and means of off-axis are combined to deposite optimal resonators of shear mode quality factor (Q) resonatros. While changing the substract and target distance between various bottom electrode materials, including Si, W/Si, and Mo/Si could deposit AlN with various c-axis tilting angle which resulted in stimulating longitudinal and shear acoustic waves. Futhermore, the finding is used to discuss the growth mechanism of inclined AlN by TEM. The analysis of various distances of AlN films shows that column inclining angle and XRD-Rocking Curve £s will increase with distance. The quality of shear mode would be better when column and £s are highly shifed. About the influence on AlN deposites, AlN/Si was grown away from the center by 6 cm. AlN/Si column inclining angle is about 20 degree, and RMS could reach 2.63nm beneath. Uner AlN/W/Si, column incling angle is about 30 degree, and £s shift angle 4.14 degree, the shear mode quality factor of freaquency response is obtained to 262. Under AlN/Mo/W/Si, column incling angle would be 25.4 degree, and XRD are better-choosed c-aixsm, £s tilting angle shifs 6.72 degree, and the shear mode quality factor is obtained to 290. Film intersurface appears bigger misfit by TEM to obtain better shear mode.
474

Multi-factor model of vertical linkages

Huang, Jing-teng 30 July 2010 (has links)
none
475

Investigation of the heavy metal contents in the environment and aquatic organisms of Chang-hua coastal area

Tsai, Wan-Jiun 30 August 2010 (has links)
Abstract The objective of this study is to investigate the heavy metal pollution in our environment by sampling and analyzing the concentration of heavy metal in seawater, sediment, and aquatic organisms from the seaside along the Chang-hua Coastal Industrial Park. The Chang-hua Coastal Industrial Park, located by the west coast of Chung-hua county in middle Taiwan, is a large-scale and multi-functional industrial estate with industrial production, residence and leisure possibilities. Hsienhsi District is situated at the northern part of the Industrial Park. Lukang District is at the southern part. In the middle of it, it is Lunwei District. In the Chung-hua Coastal Industrial Park, there are the second most electroplate and metal coating factories in Taiwan. Metal waste from the process of electroplating and coasting could easily pollute the tidal flat in Chang-hua Coastal Industrial Park. In order to prevent potential pollution taking place, this study took seawater, segment, and the aquatic organisms from the coast of the Chung-hua Coastal Industrial Park to monitoring the concentration level of copper(Cu), zinc(Zn), nickel(Ni), lead(Pb), chromium(Cr) and cadmium(Cd) in each index. The bioconcentration factor (BCF) indicates distinctions of accumulation in various matrixes. Especially from BCFW and BCFS demonstrate that soldier crab is a better index to illustrate the accumulation of Pb and Cr. Muricidae is a better index for showing Cd accumulating concentration. Furthermore, saccostreamordax is the best index for illustrating accumulative level of Ni. Oyster is better in showing accumulating of Cu and Zn. Though each organism shows distinct accumulation of particular metal, they can still illustrate the concentration of other selected metals to image the pollution of the environment. The comparison of metal accumulating levels in seawater, segment, and aquatic organisms from each test site demonstrated: the heavy metal concentration at site2 was much higher than at the other sites. The second most heavy metal concentration was at site6 and site8. Matrixes at site4 contained the lowest heavy metal concentration. The result was thought to be caused by current capacities of factories in three districts of Chang-hua Coastal Industrial Park. Site2 was at Hsienhsi Districtin, in which contained about 58% of factories in residence. In Lukang District, it reached the highest-77%-where was site 6 and site 8. In terms of Site4, it situated at Lunwei District, where was Lunwei Harbor Reservation with least development following by least capacity of factories. Furthermore, without a sound environmental-protection biological sewage treatment device, residues and chemical waste produced from various highly contaminant industries would bring about this concentration comparison result as well.
476

Design of Robust Dual Boost Converter Power Factor Correction Circuits

Zai, Zong-ru 18 October 2010 (has links)
The traditional AC/DC rectifier usually has the defects of low power factor and serious harmonic distortion and it results in serious pollution to the power system. This thesis proposes active power factor correction technique using a new AC/DC Dual Boost Converter. For power factor correction, inductor current is operated in the continuous conduction mode. First, the converter is analyzed by state space averaging method. Furthermore, we design applicable compensator by frequency analysis to implement a good power factor system. A classical PFC circuit with PI control law has low power factor under light load. In order to overcome problem, the thesis proposes a Dual Boost Converter circuit with robust performance. Comparing with circuits using PFC IC ¡§UC3854¡¨, the proposed system obtains higher power factor under the condition of the same light load.
477

Role of nuclear factor-£eB¡Vinterleukin-6 signaling pathway in ventilator-induced lung injury in mice

Ko, Yi-An 05 July 2011 (has links)
Although mechanical ventilator is a life-saving intervention, longer ventilation time and excessive tidal volume contribute to lung injury and increased incidence of infection which is associated with higher mortality. IL-6, a pleiotropic cytokine, participates in both pro- and anti-inflammatory responses. Till now, opinions of the role of IL-6 are widely divided. To study the pathogenesis mechanism of ventilator-induced lung injury (VILI), C57BL/6 mice (WT), IL-6 knockout mice (IL6-/-), chimera (IL6-/- ¡÷ WT) and deletion of I£eB kinase in the myeloid (IKK¡µmye) mice were placed on ventilator for 6 hr. WT mice were also given the IL-6-blocking antibody just before ventilation to evaluate the role of IL-6 signaling in VILI. The results revealed that the pulmonary capillary permeability, neutrophil sequestration, macrophage drifting and protein concentration in bronchoalveolar lavage fluid, and the proinflammatory cytokine levels were significantly increased in ventilated WT mice but not in those pretreated with IL-6-blocking antibody as well as IL6-/-, IKK¡µmye, and IL6-/- ¡÷ WT chimera mice, suggesting that NF-£eB¡VIL-6 signaling could induce inflammation which contributes to the VILI. Furthermore, the antibacterial ability of alveolar macrophages was impaired by ventilation that subsequently increased the danger of developing to ventilator-associated pneumonia.
478

Key Success Factors of Innovative Agriculture in Taiwan

Lin, Pei-Yao 30 August 2011 (has links)
Key Success Factors of Innovative Agriculture in Taiwan Abstract The traditional agriculture in Taiwan has a pressing need for transformation and innovation in the age of knowledge economy and economic globalization. Innovation is the core value of knowledge economy. Knowledge in itself is exclusive of all value judgment. Therefore, adding value through knowledge transfer to the product development processes can be achieved by means of new perspectives and points of view for business sustainability. The purpose of this study was to identify the key success factors (KSF) of successful promoters of innovative agriculture in the process of transformation and innovation. Three leading manufacturers of innovative agricultural products were chosen for in-depth interviews to collect specially needed data. Based on the characteristics of agricultural industry, the four dimensions of ¡§leadership quality¡¨, ¡§market strategy¡¨, ¡§product strategy¡¨, and ¡§management strategy¡¨ are used as a measure of the index of KSFs. The results show that the KSFs on the dimension of leadership quality are ¡§entrepreneurial spirit¡¨, ¡§leadership ability and foresight¡¨, ¡§cross-enterprise thinking¡¨, ¡§enterprise knowledge¡¨, and ¡§enthusiasm to help others¡¨. The KSFs on the dimension of market strategy are ¡§the ability to open up new markets¡¨, ¡§brand image¡¨, and ¡§market orientation¡¨. The KSFs on the dimension of product strategy are ¡§R&D and innovation¡¨, ¡§value-added agricultural products¡¨, ¡§product quality¡¨, and ¡§traceability system¡¨. The KSFs on the dimension of management strategy are ¡§size of business¡¨, ¡§integration¡¨, ¡§social assessment¡¨, ¡§product flow management¡¨, and ¡§core value¡¨. And finally, make recommendations to agricultural operators for moving forward with ongoing change in the economic environment. Key words: Innovative Agriculture, Key Success Factor, Knowledge Economy
479

Functional genomics analysis of the arabidopsis ABI5 bZIP transcription factor

Hur, Jung-Im 15 May 2009 (has links)
During embryogenesis, the architecture of the plant and the food reserves for seed germination are established. Abscisic acid (ABA) regulates seed development and dormancy. It controls genes involved in stress responses. ABA-responsive basic leucine zipper (bZIP) transcription factors are identified by interaction with ABA responsive cis-regulatory elements. The transcription factor ABI5 is one of these. It regulates gene expression during embryogenesis and in response to ABA. An ABA-insensitive mutant, abi5-6, exhibits no gross morphological defects other than the effect on seed germination in the presence of ABA. Thus, microarray analysis was employed to search for molecular phenotypes. We used cDNA microarrays to analyze ABA regulated gene expression and the role of ABI5 in seedlings. 310 genes were identified as ABI5/ABA regulated genes. 161 of these genes were regulated by ABI5, and 134 of ABI5-regulated genes were co-regulated by ABA. Only a small number of genes altered expression in both Pro35S:ABI5 and abi5-6 genetic backgrounds indicating the preferential binding of the bZIP protein dimers to specific promoter sequences. To determine the optimal platform for identifying ABI5-regulated genes in seeds, a cDNA microarray, the Agilent Arabidopsis Oligo microarray, and the Affymetrix ATH1 arrays were tested. Cross platform comparisons utilized 4,518 genes present on all three platforms. The best correlation was between the Agilent and the Affymetrix results. Furthermore, the Affymetrix results correlated best with qRT-PCR validation data for selected genes. A small number of genes including AtCOR413 pm-1 showed a consistent expression pattern across the three platforms. A robust ABRE cis-regulatory element was identified in the promoter of AtCOR413 pm-1. Further studies showed binding of ABI5 to the promoter of AtCOR413 pm-1 by Electrophoretic Mobility Shift Assays (EMSA) and validated the expression of ABI5 and AtCOR413 pm-1 in abi5-6 seeds by qRT-PCR and RNA gel blot analysis. Transactivation assays using AtCOR413 pm-1 promoter:GUS fusions in Arabidopsis dry seed and seedlings revealed ABI5 acts as a negative regulator for AtCOR413 pm-1 in dry seeds, while other proteins may play major roles in regulating responses to ABA and low temperature (LT) in seedlings.
480

Electrical and Production Load Factors

Sen, Tapajyoti 2009 December 1900 (has links)
Load factors are an important simplification of electrical energy use data and depend on the ratio of average demand to peak demand. Based on operating hours of a facility they serve as an important benchmarking tool for the industrial sector. The operating hours of small and medium sized manufacturing facilities are analyzed to identify the most common operating hour or shift work patterns. About 75% of manufacturing facilities fall into expected operating hour patterns with operating hours near 40, 80, 120 and 168 hours/week. Two types of load factors, electrical and production are computed for each shift classification within major industry categories in the U.S. The load factor based on monthly billing hours (ELF) increases with operating hours from about 0.4 for a nominal one shift operation, to about 0.7 for around-the-clock operation. On the other hand, the load factor based on production hours (PLF) shows an inverse trend, varying from about 1.4 for one shift operation to 0.7 for around-the-clock operation. When used as a diagnostic tool, if the PLF exceeds unity, then unnecessary energy consumption may be taking place. For plants operating at 40 hours per week, the ELF value was found to greater than the theoretical maximum, while the PLF value was greater than one, suggesting that these facilities may have significant energy usage outside production hours. The data for the PLF however, is more scattered for plants operating less than 80 hours per week, indicating that grouping PLF data based on operating hours may not be a reasonable approach to benchmarking energy use in industries. This analysis uses annual electricity consumption and demand along with operating hour data of manufacturing plants available in the U.S. Department of Energy’s Industrial Assessment Center (IAC) database. The annual values are used because more desirable monthly data are not available. Monthly data are preferred as they capture the load profile of the facility more accurately. The data there come from Industrial Assessment Centers which employ university engineering students, faculty and staff to perform energy assessments for small to medium-sized manufacturing plants. The nation-wide IAC program is sponsored by the U.S. Department of Energy.

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