• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 57
  • 20
  • 10
  • 10
  • 4
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 143
  • 143
  • 19
  • 17
  • 17
  • 15
  • 14
  • 12
  • 11
  • 10
  • 10
  • 10
  • 10
  • 9
  • 9
  • 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

New developments in IR photoelastic stress measurement methods for characterization of semiconductors. / CUHK electronic theses & dissertations collection

January 2006 (has links)
In this thesis work, a novel low level birefringence detection (LLBD) system operating at 1150 nm was set up based on the photoelastic modulation techniques. The noise level of current LLBD system is about 0.03° and the maximum fluctuation of data in ten measurements is 0.05° and close to the noise level of system. With a slit confining the light, the spatial resolution of the system is 10 mum. Optical orientation and retardation can be simultaneously measured by this system, making the stress measurement more convenience than the traditional PE methods. These peculiar features make this system capable of investigating the details of stress distribution in semiconductor structures. / Our solution reveals that the nonlinear stress filed is responsible for the shift of the zero stress point. Further it is indicated that the classical Stoney formula can either overestimate or underestimate the actual film stress due to the process induced nonlinear stress in the substrate. / Stress and strain play an essential role in determining the structural, electrical, and optical properties of semiconductor materials, and, ultimately, the semiconductor device performance. Many methods have been utilized to measure the stress in semiconductors. Among them infrared photoelasticity method is a promising one, which can be used both in the industrial characterization and scientific research. This thesis is an endeavor in this subject matter and will present our research results of studying the stress problems in semiconductor structures by using infrared photoelasticity method. / The LLBD system was applied to measure the stress distributions in the substrates of SiO2/Si structure. Some deviations from the classical film theory were observed in our experiments. For example non-linear stress fields were observed in all samples whatever their process conditions are. Besides the locations of neutral axis (zero stress point) was not located at the depth of 2/3 thickness of the substrate from the interface as expected by the bi-metallic theory. To interpret these deviations, a theoretical analysis was given to investigate the problem of stress distribution in film/substrate structure. A series of solutions were deduced to modify the Stoney formula and bi-metallic strip theory with the consideration of the nonlinear stress in substrate. / by Liu Xianghua. / "Feb 2006." / Adviser: Sai Peng Wong. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6674. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
32

Dynamic Infrared Simulation : A Feasibility Study of a Physically Based Infrared Simulation Model

Dehlin, Jonas, Löf, Joakim January 2006 (has links)
<p>The increased usage of infrared sensors by pilots has created a growing demand for simulated environments based on infrared radiation. This has led to an increased need for Saab to refine their existing model for simulating real-time infrared imagery, resulting in the carrying through of this thesis. Saab develops the Gripen aircraft, and they provide training simulators where pilots can train in a realistic environment. The new model is required to be based on the real-world behavior of infrared radiation, and furthermore, unlike Saab's existing model, have dynamically changeable attributes.</p><p>This thesis seeks to develop a simulation model compliant with the requirements presented by Saab, and to develop the implementation of a test environment demonstrating the features and capabilities of the proposed model. All through the development of the model, the pilot training value has been kept in mind.</p><p>The first part of the thesis consists of a literature study to build a theoretical base for the rest of the work. This is followed by the development of the simulation model itself and a subsequent implementation thereof. The simulation model and the test implementation are evaluated as the final step conducted within the framework of this thesis.</p><p>The main conclusions of this thesis first of all includes that the proposed simulation model does in fact have its foundation in physics. It is further concluded that certain attributes of the model, such as time of day, are dynamically changeable as requested. Furthermore, the test implementation is considered to have been feasibly integrated with the current simulation environment.</p><p>A plan concluding how to proceed has also been developed. The plan suggests future work with the proposed simulation model, since the evaluation shows that it performs well in comparison to the existing model as well as other products on the market.</p>
33

Acceleration techniques for the radiative analysis of general computational fluid dynamics solutions using reverse Monte-Carlo ray tracing /

Turk, Jeffrey A., January 1994 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 166-174). Also available via the Internet.
34

Infrared temperature patterns and inferred circulation of Lake Superior

Bratnick, Michael, January 1965 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 16-17.
35

An evaluation of limb darkening in the 8-12 micron atmospheric window

Smith, Richard Elliott. January 1967 (has links)
Thesis (M.S.)--University of Wisconsin, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 41-42).
36

A study of infrared radiation measurements in the vicinity of the subtropical tropopause

Darkow, Grant Lyle, January 1964 (has links)
Thesis (Ph. D.)--University of Wisconsin, 1964. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 64-67.
37

The role of terrestrial radiation in the generation of available potential energy

Johnson, Donald Ray, January 1965 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
38

Investigation of the Pulse Operation Wavelength Characteristics of Infrared Emitting Diodes

Kuhn, Anton G. 01 January 1976 (has links) (PDF)
No description available.
39

Application of Far Infrared Radiation and Ethanol Vapor as Alternative Treatment Methods for Reduction of Salmonella enterica Tennessee in Dried, Ground Spices

Nimitz Jr, Stephen Clark 24 May 2013 (has links)
The consumption of spiced food is steadily increasing, subsequently leading to increased incidence of spice-related food illnesses. Many outbreaks can be traced to human pathogens that can survive in low moisture content of spices, prompting development of additional inactivation treatments that reduce bacterial pathogens while maintaining spice quality. Spices are currently treated by fumigation with ethylene oxide, pasteurization with ionizing radiation, or steam treatment. However, these treatments exhibit flaws pertaining to consumer preference, regulatory issues, and quality degradation. In this study, two novel treatments were evaluated for reduction of Salmonella enterica Tennessee: far infrared radiation (FIR), a short time â " high temperature treatment, and pasteurization with ethanol vapor (EV). Both treatments were effective in reducing levels of Salmonella Tennessee between 3-5 logs. FIR treatment showed increased efficacy at longer treatment times with a maximum reduction of 5 log CFU/g in paprika at 24s. EV reduced Salmonella Tennessee by 3 log CFU/g within 120s when applied to inoculated paprika and black pepper without detrimentally affecting spice quality. However, the samples receiving FIR treatments suffered reductions in volatile content and color changes to the spices. High levels (up to 1% w/w) of residual ethanol were also detected on samples treated for 300s. Concluding, both treatment show similar results when comparing efficacy; however, based on the magnitude of change in volatile content associated with FIR being significantly greater than those samples receiving EV, FIR treatment requires additional research before recommending for use with dried, ground paprika, black pepper, or sage. / Master of Science
40

A parametric study of the validity of the weak-line and strong-line limits of infrared band absorption

Villeneuve, Pierre V. 12 March 2009 (has links)
A current version of the NASA band model was used to calculate the errors in the weakline and strong-line band absorption limits for a wide range of temperatures, pressures, path lengths, and species concentrations. The weak-line limit is valid under the condition 2u/β « 1. The strong-line limit is valid under the opposite conditions of the weak-line limit, i.e. 2u/β » 1. These two conditions are not always easily related to physical parameters such as temperature, pressure, path length, and species concentration. Therefore, the band model was used in a parametric study to calculate the weak-line limit and strong-line limit errors as a function of the temperature (100 K - 3000 K), pressure (0.0001 - 10.0 atm), path length (1 cm - 10 km), and species concentration (0.00033 - 1.0) for atmospheric and jet-exhaust-plume conditions. The results were generated in the form of spectral graphs (500 - 5000 cm⁻¹) of the limit error superimposed with the general-case absorptivity, and as contour graphs of the band-integrated limit error. The error in the contour graphs was plotted versus temperature and pressure for a given path length and species concentration. The contour graphs were generated for the 2.7 μm and 6.3 μm H₂O bands, the 2.7 μm and 4.3 μm CO₂ bands, and the medium wave (3.0 - 5.0 μm) and long wave (8.0 - 12.0 μm) bands. In the spectral graphs, the greatest error in both limits tends to occur in the core of the absorption bands when the absorption bands are small and in the band wings when the bands are relatively wide. The weak-line error generally occurs in localized pressure-temperature regimes in the contour graphs. The error is generally small at low and high temperatures and pressures, but can be significant at intermediate pressures and temperatures. The weak-line error also increases steadily with path length. The strong-line error, on the other hand, was not nearly as predictable as the weak-line error. At short path lengths, the strong-line error exhibits a linear behavior with respect to pressure. However, at longer path lengths, the strong-line error appeared saddle shaped as a function of both pressure and temperature. / Master of Science

Page generated in 0.1047 seconds