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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.
11

Low cost, short wavelenght fiber Bragg grating strain sensor systems

Vaughan, Lira 25 October 2002 (has links)
Fiber Bragg grating sensors have been constantly researched for the last ten years and have finally begun to find use in the commercial market. However, one of the major factors limiting their widespread use is their system cost. Their lightweight, flexibility, electromagnetic immunity, and small size make fiber Bragg grating (FBG) sensors feasible in hostile environments where electrical and mechanical sensors may not function effectively. These sensor systems utilize moderately expensive light sources and detectors at telecommunication wavelengths of 1300 nm and 1550 nm. These are the center wavelengths of the mass-produced FBGs and FBG phase masks. This thesis addresses the development of a lower cost short wavelength fiber Bragg grating strain sensor system using gratings written at 790 nm and 850 nm with the modified phase mask method recently developed at Oregon State University. Short wavelength gratings allow the use of less expensive semiconductor sources and silicon detectors, greatly reducing the overall cost of a strain sensor system from approximately $1600 for a 1300 nm system to $1000 for a 790 nm system. First, the fundamental properties and historical background of fiber Bragg gratings were reviewed. Followed by a literature review of the structures, fabrication methods, and applications of FBGs including sensor applications. The design, manufacture, and assembly of the new short wavelength strain sensor system were described including the production of pigtailed super-luminescent edge emitting light emitting diodes (SELED) from commercial laser diodes, a fiber recoater, and multiple attempts to write a fiber Bragg grating in the 750-850 nm wavelength region. Finally, the short wavelength strain sensor system was compared with a 1300 nm strain sensor detailing the potential cost savings with the short wavelength system. / Graduation date: 2003
12

Tool wear detection and self-induced vibrations control in turning operations

Orozco Mendoza, Horacio. January 2002 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.
13

Optical fiber modal domain sensors for dynamic strain measurement /

Bennett, K. D., January 1990 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 196-206). Also available via the Internet.
14

Novel fabrication processes for thin film vapour deposited strain gauges on mild steel

Djugum, Richard. January 2006 (has links)
Thesis (PhD) - Swinburne University of Technology, School of Engineering and Science, 2006. / A thesis submitted for the degree of Doctor of Philosophy, School of Engineering and Science, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 125-138).
15

Floating head skin friction gage measurements in supersonic flows /

Lattimer, Brian Y., January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 122-123). Also available via the Internet.
16

High temperature fiber optic strain sensing /

Koob, Christopher E., January 1991 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 91-93). Also available via the Internet.
17

Análise da distribuição de cargas e das forças entre asseno e encosto, na postura sentada adequada

Resende, Fernanda de Lima e Sá [UNESP] 11 August 2006 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-11Bitstream added on 2014-06-13T20:37:39Z : No. of bitstreams: 1 resende_fls_me_guara.pdf: 781042 bytes, checksum: 90a752d449437b2098cb5b1a50b2cae7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi estudar a distribuição das cargas no sistema cadeira plataforma de força (C-PF) e verificar se há correlação entre as forças medidas no assento e encosto, na postura sentada adequada. Participaram 38 voluntários, classificados pelo biótipo (32 mulheres e 6 homens): idade média de 43,92 anos, estatura média de 1,60 m e peso corporal médio de 65,10 kgf. Uma cadeira, com células de carga nas partes anterior e posterior do assento e no encosto, e uma plataforma de força mediram a distribuição do peso corporal. Estabeleceram-se várias correlações entre as variáveis (peso corporal, altura, idade, e índice de massa corporal) e as cargas medidas e entre as próprias forças adquiridas. Uma das correlações determinou uma relação entre a força total no assento e a força medida no encosto. A distribuição do peso corporal observada foi: 20,04% na plataforma de força; 45,33% e 30,43%, nas partes anterior e posterior do assento, respectivamente; e 4,20% no encosto. Não houve diferenças estatísticas significativas na comparação das médias dos valores da distribuição do peso corporal tanto entre os sexos como entre os biótipos. Porém, como há diferenças na forma corporal de acordo com os sexos e com os biótipos, houve certa diferença nos valores das forças medidas, no sistema C-PF. / The aim of this study was to study the load distribution in chair-force plate system (CFP) and to verify if there is correlation between measured seat and backrest forces in the adequate sitting posture. 38 volunteers participated of the study, classifieds according to physical types (32 female and 6 male): mean age of 43,92 years old, mean height of 1,60 m and mean body weight of 65,10 kgf. An instrumented office chair with load cells in the anterior and posterior portions of the seat and backrest and a force plate were used to measure the forces and body weight distribution in C-FP system. This study was established many correlations among some variables (body weight, height, age and body mass index) and the measured loads and among the acquired forces. One of these correlations determined a relation among total force measured on seat and acquired force on lumbar backrest. The body weight distribution observed in the C-FP system was: 20,04% in the force plate, 45,33% and 30,43% in the anterior and posterior portions of the seat respectively, and 4,20% in the backrest. There were no statistics significant differences in comparison of values weight distribution averages as between gender as between physical patterns. But, there are some differences in the body shape according to gender and physical patterns, it there was some difference in the values of acquired forces in the C-FP system.
18

A COMPARISON OF METHODS FOR MEASUREMENT OF PRESSURE IN HYDRAULIC LINES

Sprague, Susan, Chorney, Andrew 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This presentation summarizes a study characterizing strain gages and pressure transducers used to measure the fluid pressure within aircraft hydraulic lines. A series of laboratory calibrations and finite element analyses was performed to demonstrate the quality of data from both pressure transducers and strain gages under variations in both temperature and external strains on the hydraulic lines. Strain gages showed a marked susceptibility to external strains on hydraulic lines, and wide variations in susceptibility to temperature changes. Pressure transducers were found to be relatively immune to both conditions. It is recommended that strain gages be used for trend data only.
19

FLIGHT TEST INSTRUMENTATION FOR THE ADVANCED HAWKEYE LOADS RISK REDUCTION PROJECT

Bedgar, Kenda J., Cullison, Anthony J. 10 1900 (has links)
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper is about the installation of the instrumentation system and the strain gages on an E-2C Hawkeye for the Advanced Hawkeye Loads Risk Reduction project. Background information on why this project came about will be given. Explanations on why the existing instrumentation system was modified to the current system will be presented. Anthony Cullison (co-author of this paper) will explain the installation of the strain gages.
20

Geophysical strain and tilt : measurement methodology and analysis of data

MacKay, Robert 01 January 1983 (has links)
Tilt and strain meters were installed on the Portland State University campus in the summer of 1982 and data was collected for 4 months. Instrument selection, operation, installation and performance are discussed. Suggestions that could enhance data quality and data collection efficiency are presented. An analysis procedure is suggested and an example of this procedure for an interval of data is discussed. The influence of the temperature, pressure, rainfall and solid earth tides on the signal is investigated, as well as the correlation between similar channels of the different tilt instruments. The temperature, rainfall and solid earth tides were all determined to have an influence on the instruments. A statistical test of the influence of the barometric pressure on the signal revealed no significant influence. A very low correlation between similar components of the different tilt instruments was observed aside from their thermal dependence. It was concluded that in order to obtain high quality data for the use in quantitative calculations, the temperature influence on the raw record must be minimized.

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