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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.
31

Fabrication of SiO2 barrier layer by magnetron sputtering and supercritical CO2 fluids treatment for silicon solar cells

Wei, Ji-Rong 12 July 2011 (has links)
In this thesis, silicon oxide thin films fabricated on silicon substrates by reactive radio frequency (rf) magnetron sputtering and supercritical CO2 (SCCO2) treatment at room temperature were investigated. The electrical properties including I-V and C-V of the films prepared at different processing conditions were discussed. Using the Transmission Electron Microscope (TEM), the thickness of silicon oxide thin films were measured. The results suggested that the film quality can be significantly improved by the SCCO2 treatment after reactive sputtering. The leakage current of the films at an electrical field of 1 MV/cm is 1¡Ñ10-8A/cm2 with a hysteresis voltage of 0.01V. The silicon oxide thin films can be used as a barrier layer for Al/SiO2/Si silicon solar cells. The energy conversion efficiency of a single crystal silicon solae cell is 10.2% under AM1.5 (965W/m2) radiation. After rapid thermal annealing(RTA) at 500¢J, the measured short-circuit current, open- circuit voltage, fill factor are 53mA, 0.54V and 0.53, respectively.
32

Power supply noise in delay testing

Wang, Jing 15 May 2009 (has links)
As technology scales into the Deep Sub-Micron (DSM) regime, circuit designs have become more and more sensitive to power supply noise. Excessive noise can significantly affect the timing performance of DSM designs and cause non-trivial additional delay. In delay test generation, test compaction and test fill techniques can produce excessive power supply noise. This will eventually result in delay test overkill. To reduce this overkill, we propose a low-cost pattern-dependent approach to analyze noise-induced delay variation for each delay test pattern applied to the design. Two noise models have been proposed to address array bond and wire bond power supply networks, and they are experimentally validated and compared. Delay model is then applied to calculate path delay under noise. This analysis approach can be integrated into static test compaction or test fill tools to control supply noise level of delay tests. We also propose an algorithm to predict transition count of a circuit, which can be applied to control switching activity during dynamic compaction. Experiments have been performed on ISCAS89 benchmark circuits. Results show that compacted delay test patterns generated by our compaction tool can meet a moderate noise or delay constraint with only a small increase in compacted test set size. Take the benchmark circuit s38417 for example: a 10% delay increase constraint only results in 1.6% increase in compacted test set size in our experiments. In addition, different test fill techniques have a significant impact on path delay. In our work, a test fill tool with supply noise analysis has been developed to compare several test fill techniques, and results show that the test fill strategy significant affect switching activity, power supply noise and delay. For instance, patterns with minimum transition fill produce less noise-induced delay than random fill. Silicon results also show that test patterns filled in different ways can cause as much as 14% delay variation on target paths. In conclusion, we must take noise into consideration when delay test patterns are generated.
33

Determination of soil properties for sandy soils and road base at Riverside Campus using laboratory testing and numerical simulation

Saez Barrios, Deeyvid O. 2010 May 1900 (has links)
This study evaluated the soil properties of clean sand, a silty sand, and a road base that are extensively used as a backfill for full-scale testing at Riverside Campus at Texas A&M University. The three soils were collected at the Riverside Campus and the testing schedule included grain size analysis, hydrometer test, specific gravity, maximum dry density, Atterberg limit, stiffness, direct shear test, triaxial test, and a simple procedure to estimate the maximum and minimum void ratio of the clean sand. Relation between strength/deformation, vertical displacement/shear displacement, and physical properties were evaluated to estimate the frictional resistance and angle of dilation of the clean sand and the silty sand. Numerical simulations of the Direct Shear Test (DST) were conducted on the clean sand using Finite Element Model in the computer program LS-DYNA. The simulations were intended to reproduce the Direct Shear Test (DST) to estimate the frictional resistance and dilatancy effects of the clean sand under different compressive stresses. Field tests were also conducted on the clean sand and the road base. These tests included the in-situ density determination, in-situ water content, and the soil modulus using the Briaud Compaction Device (BCD).
34

Design and Fabrication of A Diffuser Film with Two Layers of Microlens Arrays

Chen, Ming-Fa 29 July 2009 (has links)
Integrated microlens array on a transparent film, called an optical film, provides interesting applications for various fields. In a FPD (Flat Panel Display), the optical films are the more important components to improve the efficiency and quality. In this dissertation, a diffuser film which consisted of two different microlens arrays on the two surfaces of a film was developed and used to enhance the brightness and uniformity of a light source. There were also several microlens arrays developed, such as a hexagonal microlens array with gap and gapless, a gapless dual-curvature microlens array and a diffuser film. A process called polygonal microlens array process had been used to manufacture them. It had advantages of mass production, various polygonal shapes and 100% fill-factor. A softer mold of PDMS and a metal mold of NiCo alloy were utilized to replicate the MLAs. In this dissertation, several replication processes were applied to mass product and to find out which one is more suitable for the diffuser film. In this dissertation, the results of different shapes and dimensions of microlens arrays showed various light distribution. Therefore, for searching a more suitable and novel layout of a diffuser, Taguchi Method with simulation was used to design the layout of a diffuser film before fabrication process. Finally, a diffuser film was measured and demonstrated its optical effects. According to the results of measurement and simulation, the average intensity and the S/N ratios were shown. The trend of simulation and measurement was also similar.
35

Environmental exposure assessment of metals from reclaimed land in Halmstad harbour : Sweden  Part of an environmental risk assessment

Assarsson, Karin January 2015 (has links)
The harbour land fill in Halmstad has been described in the news as one of the most polluted areas in Halland County based on the a survey from the Swedish environmental protection agency. In order to identify the extent and severity of the situation several environmental investigations have been performed in this area. This report is based on available data from investigations and environmental reports from WSP, Höganäs AB, HEM and Halmstad municipality. This investigation focus on an “Area C” within the land fill where the main land fill material is i.a. slag from a steel work, construction waste, dredge spoil, waste from glass production and a casting shop. Of these material the focus have been on the metal rich slag from the steel work and its possible environmental impact. The environmental exposure of Hg, Pb, Cd, Cr, Zn, Ni, Mo and V have been calculated as an annual load from Area C. Unfortunately the data available for this investigation has not been complete, e.g. slag concentration data with corresponding leachate data was only obtained for one year. The groundwater data and land fill metal concentrations have been measured only once. This made it impossible to investigate e.g. annual variations like ageing effects of the material or weather variations, variation in the properties of the deposed slag material and statistical significance in differences could not be calculated. Further characterisation of the land fill would be worthwhile in order to be able to draw some conclusions. Calculations of the environmental load has been performed based on concentration in the slag, the land fill, the leachate data of the slag and groundwater concentrations. A model has been developed to calculate the weighted land fill metal concentration. The partitioning coefficient, Kd; between soil and liquid has been calculated and used to estimate the environmental load. It was assumed that the groundwater data was the most reliable data, which indicated that the exposure may be higher than from common soil, especially for Pb and Mo. Relating the environmental exposure values with guideline values based on MKM (less sensitive land use)-land using HQ (hazard quotient) indicates a decreasing risk in the order Pb>V>Mo. However, the exposure is well below that from MKM soil which could be assumed, according to Swedish environmental protection agency guideline values, to be an acceptable exposure.
36

Temporal variability of riverbed hydraulic conductivity along the Great Miami River, southwest Ohio a continuance of data gathering and instrumentation /

Windeler, Britton. January 2006 (has links)
Thesis (M. En.)--Miami University, Institute of Environmental Sciences, 2006. / Title from first page of PDF document. Includes bibliographical references (p. 32-35).
37

Roadway effects on the hydrologic regime of temporary wetlands in the Missouri River floodplain in Missouri

Horton, Kimberly. January 2005 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 11, 2007) Includes bibliographical references.
38

Iceberg scour risk analysis for pipelines on the Labrador Shelf /

King, Anthony D., January 2002 (has links)
Thesis (M.Eng.)--Memorial University of Newfoundland, 2003. / Bibliography: leaves 204-212.
39

Fatores limitantes do consumo de capim-elefante cv. Napier utilizando vacas leiteiras confinadas

Soares, João Paulo Guimarães [UNESP] 01 July 2002 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:33:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-07-01Bitstream added on 2014-06-13T19:44:25Z : No. of bitstreams: 1 soares_jpg_dr_jabo.pdf: 336350 bytes, checksum: b7c430f6a886cefb0db991d9ccbc1c6e (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O Consumo de matéria seca (CMS), de fibra em detergente neutro (CFDN), o enchimento físico ruminal, as taxas de passagem no rúmen e pós-rúmen e o efeito da suplementação com concentrado sobre o consumo de MS da forragem foram avaliados com o objetivo de identificar os fatores limitantes do consumo de vacas leiteiras, em confinamento, que receberam capim-elefante picado e cortado com 30, 45 e 60 dias de crescimento. O CMS (8,0 kg/vaca/dia) e CFDN (5,3 kg/vaca/dia) obtidos com o capim cortado com 30 dias, foram inferiores (P<0,05) àqueles obtidos com 45 dias (10,0 e 6,6 kg/vaca/dia) e 60 dias (11,0 e 7,3 kg/vaca/dia), respectivamente. O CMS dos tratamentos com 30 e 45 dias foram semelhantes (P>0,05). O conteúdo máximo ruminal de FDN ocorreu às 4h22 (7,40 kg), 3h55 (7,60 kg) e 3h49 (7,57 kg) após o oferecimento do capim cortado com 30, 45 e 60 dias de idade, respectivamente. A taxa de passagem das partículas de FDN, com o tamanho de 2,38 mm do capim-elefante suplementado com 4 kg (3,7%/h), foi superior (P<0,05) ao capim sem suplementação (3,1%/h). O capim suplementado com 2 kg (3,4%/h) foi semelhante (P>0,05) aos outros dois tratamentos. Ocorreu efeito associativo combinado entre o CMS do capim e do suplemento. O enchimento físico do rúmen não limitou o consumo FDN, entretanto o teor de umidade do capim afetou o enchimento físico, limitando o consumo de MS do capim-elefante. / Dry matter intake (DMI), neutral detergent fiber intake (NDFI), rumen fill, NDF rumen and post-rumen rates of passages and the effect of the concentrate supplementation on forage DMI were evaluated to determine the limiting factors intake of crossbred dairy cows managed in a free stall system fed chopped elephantgrass harvested at 30, 45 and 60 days of growth. The average DMI (8.0 kg/cow/day) and NDFI (5.3 kg/cow/day) values were lower (P<.05) for the 30 days elephantgrass than those for the 45 days (10.0 and 6.6 kg/cow/day) and 60 days (11.0 and 7.3 kg/cow/day) for the DMI and NDFI, respectively. The average DMI of the 45 and 60 days treatments were similar (P>.05). The maximum NDF rumen fill content was observed at 4h22 (7.40 kg), 3h55 (7.60 kg) and 3h49 (7.57 kg) after feeding for the treatments with 30, 45 and 60 days of growth, respectively. NDF rumen passage rate for particles sizes with 2.38 mm of elephantgrass supplemented with 4 kg (3.7%/h) was higher (P<.05) to 2 kg (3.1%/h). There was no treatment effect (P>.05) in the NDF rumen passage rate without concentrate supplementation (3.4%/h) and the two supplemented treatments. A combined associative effect on the DMI was observed on the two levels of concentrate. There was no treatments effect (P>.05) in the rumen fill for the NDF intake of cows, probably due to the low dry matter content of the forage.
40

Fluvial to estuarine transition in the middle Bloyd sandstone (Morrowan), northwest Arkansas

Unrein, Kevin Scott January 1900 (has links)
Master of Science / Department of Geology / Allen W. Archer / The Morrowan middle Bloyd sandstone of northwest Arkansas records a fluvial to estuarine transition in a drowned incised valley system. Lower portions of outcrops contain fluvially deposited, planar-tabular cross-stratified sandstone with a uni-directional southwest paleoflow. Intervals with dune scale, intricately interwoven trough cross-stratification with northeastern paleoflow is attributed to strong tidal and wave influence in the outer estuary. Upwards the middle Bloyd changes into a muddy mid-estuarine interval with heterolithic bedding and a bi-directional northeast-southwest paleoflow. Overlying this interval a marine sand about one meter in thickness can be found containing bryozoan and crinoid fossils. Overlying the middle Bloyd, the marine Dye Shale member of the Bloyd Formation marks the transition to a dominantly marine setting.

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