M.Ing. (Mechanical Engineering) / Please refer to full text to view abstract

Orientador: José Geraldo Trani Brandão / Banca: Celso Pinto Morais Pereira / Banca: Marcio Augusto Martin / Resumo: 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. / Abstract: 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. / Mestre

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / Microfiche copy available in Archives and Barker. / Bibliography: p.80-81. / M.S.

This thesis reports the research and industry-related works carried out from the development of a fibre-optic strain sensor system for Civil Engineering applications. A sensor system consists of a number of core components, including the sensing element, interrogation/demodulation, multiplexing, signal processing and hardware equipment. In the process of development, a number of issues have been identified and investigated, which resulted in the improvement of the system performance, as well as the proposal of new techniques for the sensor system. First, an improved demodulation technique for a type of sensor, namely the fibre Fizeau interferometer (FFI), is presented. The technique is based on the improvement of the Fourier transform peak detection method, which suffers severely from the poor resolution and accuracy of finding the sensor cavity length. The improvement over the original method has been compared and verified through simulations and experiments. Second, a simultaneous demodulation technique for multiplexed FFI and fibre Bragg grating (FBG) sensors using the discrete wavelet transform (DWT) is proposed. Third, a multiplexing technique using amplitude-modulated chirped FBGs and the DWT is proposed. These two proposed techniques have been demonstrated experimentally through strain measurements. The strain resolution, crosstalk and limitations are investigated. In addition, simultaneous quasi-static strain and temperature sensing of different metal plates are performed. Fibre-optic sensors have found numerous applications in different areas. In this thesis, the use of FBG sensors in Civil Engineering applications is demonstrated in four experimental studies, including: (i) long-term measurement of drying shrinkage and creep of structural grade concrete; (ii) simultaneous measurement of shrinkage and temperature of reactive powder concrete (RPC) at early-age; (iii) measurement of coefficients of thermal expansion of cement mortar and RPC; and (iv) field-trial on the strain monitoring of the world?s first RPC road bridge. In addition, the experimental and practical issues of using FBG sensors are considered.

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This thesis reports the research and industry-related works carried out from the development of a fibre-optic strain sensor system for Civil Engineering applications. A sensor system consists of a number of core components, including the sensing element, interrogation/demodulation, multiplexing, signal processing and hardware equipment. In the process of development, a number of issues have been identified and investigated, which resulted in the improvement of the system performance, as well as the proposal of new techniques for the sensor system. First, an improved demodulation technique for a type of sensor, namely the fibre Fizeau interferometer (FFI), is presented. The technique is based on the improvement of the Fourier transform peak detection method, which suffers severely from the poor resolution and accuracy of finding the sensor cavity length. The improvement over the original method has been compared and verified through simulations and experiments. Second, a simultaneous demodulation technique for multiplexed FFI and fibre Bragg grating (FBG) sensors using the discrete wavelet transform (DWT) is proposed. Third, a multiplexing technique using amplitude-modulated chirped FBGs and the DWT is proposed. These two proposed techniques have been demonstrated experimentally through strain measurements. The strain resolution, crosstalk and limitations are investigated. In addition, simultaneous quasi-static strain and temperature sensing of different metal plates are performed. Fibre-optic sensors have found numerous applications in different areas. In this thesis, the use of FBG sensors in Civil Engineering applications is demonstrated in four experimental studies, including: (i) long-term measurement of drying shrinkage and creep of structural grade concrete; (ii) simultaneous measurement of shrinkage and temperature of reactive powder concrete (RPC) at early-age; (iii) measurement of coefficients of thermal expansion of cement mortar and RPC; and (iv) field-trial on the strain monitoring of the world?s first RPC road bridge. In addition, the experimental and practical issues of using FBG sensors are considered.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 156-158)

Thesis (Ph.D.)--McMaster University, 2004. / Supervisor: D.S. Wilkinson. Includes bibliographical references (leaves 164-170). Also available via World Wide Web.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.

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