<p>Focusing of strong shock waves in a gas-filled thin test section with various forms of the reflector boundary is investigated. The test section is mounted at the end of the horizontal co-axial shock tube. Two different methods to produce shock waves of various forms are implemented. In the first method the reflector boundary of the test section is exchangeable and four different reflectors are used: a circle, a smooth pentagon, a heptagon and an octagon. It is shown that the form of the converging shock wave is influenced both by the shape of the reflector boundary and by the nonlinear dynamic interaction between the shape of the shock and the propagation velocity of the shock front. Further, the reflected outgoing shock wave is affected by the shape of the reflector through the flow ahead of the shock front. In the second method cylindrical obstacles are placed in the test section at various positions and in various patterns, to create disturbances in the flow that will shape the shock wave. It is shown that it is possible to shape the shock wave in a desired way by means of obstacles. The influence of the supports of the inner body of the co-axial shock tube on the form of the shock is also investigated. A square shaped shock wave is observed close to the center of convergence for the circular and octagonal reflector boundaries but not in any other setups. This square-like shape is believed to be caused by the supports for the inner body. The production of light, as a result of shock convergence, has been preliminary investigated. Flashes of light have been observed during the focusing and reflection process.</p>

Analysis of vibration transmission and reflection in beam-like engineering structures requires better predictive models to optimise structural behaviour further. Numerous studies have used flexural and longitudinal structural wave motion to model the vibrational response of angled junctions in beam-like structures, to better understand the transmission and reflection properties. This study considers a model of a variable joint angle which joins two semi-infinite rectangular cross-section beams. In a novel approach, the model allows for the joint to expand in size as the angle between the two beams is increased. The material, geometric and dynamics properties were consistently being considered. Thus, making the model a good representation of a wide range of angles. Predicted results are compared to an existing model of a joint between two semi-infinite beams where the joint was modelled as a fixed inertia regardless of the angle between the beams, thus limiting its physical representation, especially at the extremes of angle (two beams lay next to each other at 180 degree joint). Results from experimentation were also compared to the modelling, which is in good agreement for the range of angles investigated. Optimum angles for minimum vibrational power transmission are identified in terms of the frequency of the incoming flexural or longitudinal wave. Extended analysis and effect of adding stiffness and damping (rubber material) at the joint are also reported.

A determinação da rugosidade é parte fundamental para a classificação da qualidade de uma superfície. Assim, iniciou-se este trabalho realizando-se estudos a respeito de seus métodos de medição. Devido à grande adaptabilidade e à velocidade dos métodos a laser, os estudos foram direcionados para estes tipos de técnicas de medição. Verificou-se que esses dispositivos vinculavam-se a sistemas em que o laser refletido era analisado através de sistemas com detectores do tipo CCD, em que a imagem refletida era analisada num todo. Assim, a bibliografia trouxe inspiração para mensurar a rugosidade de uma superfície gerada por torneamento horizontal, a partir da intensidade laser refletida. Propôs-se, então, um método baseado exclusivamente, na intensidade do sinal que era refletido pela superfície em estudo, a contar de uma incidência normal, já que aos autores ressaltavam que quanto maior a rugosidade da superfície menor seria o sinal refletido por ela. O sistema foi montado e sua capacidade de diferenciar distintas rugosidades foi testada. Então foram produzidas amostras com diferentes rugosidades, a fim de se obter uma função que pudesse correlacionar o sinal laser com a respectiva rugosidade (medida esta feita em rugosímetro de agulha). A função de transferência encontrada foi testada em amostras dissemelhantes das que a geraram, com o intuito de comprovar sua eficácia. Amostras fabricadas com ferramentas distintas de corte também foram produzidas e submetidas ao mesmo procedimento. As funções de transferência geradas alcançaram sucesso na previsão da rugosidade em, no máximo, 16,6% dos pontos, considerando uma margem de erro de 20%. A seguir, procurando-se os motivos que pudessem ter causado este percentual, levantou-se a possibilidade de estarem ocorrendo efeitos ópticos capazes de causar interferências devido às irregularidades na superfície. Efeitos capazes de degenerarem o sinal refletido. A comprovação de que o sinal eventualmente poderia estar sendo perturbado aconteceu através de referência bibliográfica e de imagens obtidas por microscopia eletrônica de varredura, em que se pôde observar a existência de estruturas na face das amostras que seriam isolada ou conjuntamente capazes de causar os efeitos citados. / The determination of the roughness is a key for a good classification of a surface. Thereby, the work was started with a study about the roughness measurements methods. Due to the great adaptability and speed of laser methods, the studies were directed to these kinds of measurement techniques. It was observed in the literature that these laser devices were linked to systems where the reflected laser was analyzed by systems with CCD detectors, where the reflected image was entirely analyzed. Hence, the bibliography brought inspiration to measure the surface roughness generated by axial turning from the intensity of the reflected laser. It was proposed then a measurement method exclusively based on the intensity of the signal that was reflected by the surface under study, because the authors noted that as the roughness of surface became bigger as the signal reflected is became smaller. The proposed system has been assembled and ability to distinguish different roughness was tested successfully. Then samples were produced with different roughness in order to obtain a function that would correlate the laser signal with its roughness (this measurement is made by tactile measurement instrument). The transfer function obtained was tested on different samples that generated in order to prove its efficacy. Samples produced with different cutting tools were also produced and subjected to the same procedure. The transfer functions reached a successful prediction of the roughness maximum for 16.6% of the points assuming a margin of error of 20%. So, looking up the reasons that could have caused this percentage we think the possibility as the occurrence of some optical effects that can cause interference due to irregularities on the surface. These optical effects can degenerate the reflected signal. The proof that the signal could possibly be corrupted was made by the bibliographic references and some images obtained by scanning electron microscopy in which they could observe the existence of structures on the sample surfaces that would can be a reason for these effects individually or together.

A determinação da rugosidade é parte fundamental para a classificação da qualidade de uma superfície. Assim, iniciou-se este trabalho realizando-se estudos a respeito de seus métodos de medição. Devido à grande adaptabilidade e à velocidade dos métodos a laser, os estudos foram direcionados para estes tipos de técnicas de medição. Verificou-se que esses dispositivos vinculavam-se a sistemas em que o laser refletido era analisado através de sistemas com detectores do tipo CCD, em que a imagem refletida era analisada num todo. Assim, a bibliografia trouxe inspiração para mensurar a rugosidade de uma superfície gerada por torneamento horizontal, a partir da intensidade laser refletida. Propôs-se, então, um método baseado exclusivamente, na intensidade do sinal que era refletido pela superfície em estudo, a contar de uma incidência normal, já que aos autores ressaltavam que quanto maior a rugosidade da superfície menor seria o sinal refletido por ela. O sistema foi montado e sua capacidade de diferenciar distintas rugosidades foi testada. Então foram produzidas amostras com diferentes rugosidades, a fim de se obter uma função que pudesse correlacionar o sinal laser com a respectiva rugosidade (medida esta feita em rugosímetro de agulha). A função de transferência encontrada foi testada em amostras dissemelhantes das que a geraram, com o intuito de comprovar sua eficácia. Amostras fabricadas com ferramentas distintas de corte também foram produzidas e submetidas ao mesmo procedimento. As funções de transferência geradas alcançaram sucesso na previsão da rugosidade em, no máximo, 16,6% dos pontos, considerando uma margem de erro de 20%. A seguir, procurando-se os motivos que pudessem ter causado este percentual, levantou-se a possibilidade de estarem ocorrendo efeitos ópticos capazes de causar interferências devido às irregularidades na superfície. Efeitos capazes de degenerarem o sinal refletido. A comprovação de que o sinal eventualmente poderia estar sendo perturbado aconteceu através de referência bibliográfica e de imagens obtidas por microscopia eletrônica de varredura, em que se pôde observar a existência de estruturas na face das amostras que seriam isolada ou conjuntamente capazes de causar os efeitos citados. / The determination of the roughness is a key for a good classification of a surface. Thereby, the work was started with a study about the roughness measurements methods. Due to the great adaptability and speed of laser methods, the studies were directed to these kinds of measurement techniques. It was observed in the literature that these laser devices were linked to systems where the reflected laser was analyzed by systems with CCD detectors, where the reflected image was entirely analyzed. Hence, the bibliography brought inspiration to measure the surface roughness generated by axial turning from the intensity of the reflected laser. It was proposed then a measurement method exclusively based on the intensity of the signal that was reflected by the surface under study, because the authors noted that as the roughness of surface became bigger as the signal reflected is became smaller. The proposed system has been assembled and ability to distinguish different roughness was tested successfully. Then samples were produced with different roughness in order to obtain a function that would correlate the laser signal with its roughness (this measurement is made by tactile measurement instrument). The transfer function obtained was tested on different samples that generated in order to prove its efficacy. Samples produced with different cutting tools were also produced and subjected to the same procedure. The transfer functions reached a successful prediction of the roughness maximum for 16.6% of the points assuming a margin of error of 20%. So, looking up the reasons that could have caused this percentage we think the possibility as the occurrence of some optical effects that can cause interference due to irregularities on the surface. These optical effects can degenerate the reflected signal. The proof that the signal could possibly be corrupted was made by the bibliographic references and some images obtained by scanning electron microscopy in which they could observe the existence of structures on the sample surfaces that would can be a reason for these effects individually or together.

A determinação da rugosidade é parte fundamental para a classificação da qualidade de uma superfície. Assim, iniciou-se este trabalho realizando-se estudos a respeito de seus métodos de medição. Devido à grande adaptabilidade e à velocidade dos métodos a laser, os estudos foram direcionados para estes tipos de técnicas de medição. Verificou-se que esses dispositivos vinculavam-se a sistemas em que o laser refletido era analisado através de sistemas com detectores do tipo CCD, em que a imagem refletida era analisada num todo. Assim, a bibliografia trouxe inspiração para mensurar a rugosidade de uma superfície gerada por torneamento horizontal, a partir da intensidade laser refletida. Propôs-se, então, um método baseado exclusivamente, na intensidade do sinal que era refletido pela superfície em estudo, a contar de uma incidência normal, já que aos autores ressaltavam que quanto maior a rugosidade da superfície menor seria o sinal refletido por ela. O sistema foi montado e sua capacidade de diferenciar distintas rugosidades foi testada. Então foram produzidas amostras com diferentes rugosidades, a fim de se obter uma função que pudesse correlacionar o sinal laser com a respectiva rugosidade (medida esta feita em rugosímetro de agulha). A função de transferência encontrada foi testada em amostras dissemelhantes das que a geraram, com o intuito de comprovar sua eficácia. Amostras fabricadas com ferramentas distintas de corte também foram produzidas e submetidas ao mesmo procedimento. As funções de transferência geradas alcançaram sucesso na previsão da rugosidade em, no máximo, 16,6% dos pontos, considerando uma margem de erro de 20%. A seguir, procurando-se os motivos que pudessem ter causado este percentual, levantou-se a possibilidade de estarem ocorrendo efeitos ópticos capazes de causar interferências devido às irregularidades na superfície. Efeitos capazes de degenerarem o sinal refletido. A comprovação de que o sinal eventualmente poderia estar sendo perturbado aconteceu através de referência bibliográfica e de imagens obtidas por microscopia eletrônica de varredura, em que se pôde observar a existência de estruturas na face das amostras que seriam isolada ou conjuntamente capazes de causar os efeitos citados. / The determination of the roughness is a key for a good classification of a surface. Thereby, the work was started with a study about the roughness measurements methods. Due to the great adaptability and speed of laser methods, the studies were directed to these kinds of measurement techniques. It was observed in the literature that these laser devices were linked to systems where the reflected laser was analyzed by systems with CCD detectors, where the reflected image was entirely analyzed. Hence, the bibliography brought inspiration to measure the surface roughness generated by axial turning from the intensity of the reflected laser. It was proposed then a measurement method exclusively based on the intensity of the signal that was reflected by the surface under study, because the authors noted that as the roughness of surface became bigger as the signal reflected is became smaller. The proposed system has been assembled and ability to distinguish different roughness was tested successfully. Then samples were produced with different roughness in order to obtain a function that would correlate the laser signal with its roughness (this measurement is made by tactile measurement instrument). The transfer function obtained was tested on different samples that generated in order to prove its efficacy. Samples produced with different cutting tools were also produced and subjected to the same procedure. The transfer functions reached a successful prediction of the roughness maximum for 16.6% of the points assuming a margin of error of 20%. So, looking up the reasons that could have caused this percentage we think the possibility as the occurrence of some optical effects that can cause interference due to irregularities on the surface. These optical effects can degenerate the reflected signal. The proof that the signal could possibly be corrupted was made by the bibliographic references and some images obtained by scanning electron microscopy in which they could observe the existence of structures on the sample surfaces that would can be a reason for these effects individually or together.

For the past several decades, challenges in the detection and collection of latent prints exposed to harsh environmental conditions have inspired research in pretreatment methods prior to the application of chemical, physical, or optical-based enhancement techniques. Some of the difficulties associated with processing degraded latent prints are attributed to dehydration, alterations in chemical composition, and physical disturbance of ridge detail. This study seeks to investigate the effectiveness of humidity, cyanoacrylate fuming method (CFM), and a reflected ultraviolet imaging system (RUVIS) on the detection and collection of aged latent palmprints. Prints were exposed to air flow and ultraviolet (UV) light for a period of 0 to 28 days, and subsequently treated with either cool or warm humidity and CFM. RUVIS was then utilized to detect and capture friction ridge detail after each treatment step. Improvements in RUVIS detection between treatments were evaluated based on four response factors: minutiae count, percent print recovery, ridge thickness and contrast. By measuring these factors, each latent print photograph was able to be converted to quantifiable data to facilitate statistical analysis of potential differences or improvements between treatments. The results demonstrate that the application of 80% relative humidity successfully revived aged latent palmprints across all factors. The combined effect of humidity followed v by CFM treatment and RUVIS detection was greatest for minutiae count and ridge thickness, while percent print recovery and contrast demonstrated more modest improvements when compared to control prints. Additionally, cool temperature treatments outperformed warm temperature treatments across all factors except contrast. The data therefore suggest that to achieve print rejuvenation and overall improvements in RUVIS detection, combined cool humidity and CFM is more effective than humidity alone. The data also indicate a potential correlation between temperature treatments and latent print age. Warm humidity combined with CFM appeared to best enhance RUVIS images on fresher prints of a few days to one week old, while cool humidity and CFM appeared to maximally enhance RUVIS images on prints of several weeks old.

This study explored the peer perceptions of adolescent heterosexual males and their homosexual counterparts who had not disclosed their feelings of erotic same-sex attraction to their classmates. The study focused on members of The Church of Jesus Christ of Latter-day Saints, a conservative Christian denomination with clear doctrinal prohibitions against homosexual behavior. The handwritten messages from peers found in the senior high school yearbooks of 30 heterosexual and 30 same-sex attracted adolescent men were content analyzed to examine similarities and differences in the themes that emerged from the data. The results indicated that there is a difference in the kind of activities that are common in the lives of these heterosexual and same-sex attracted males. The same-sex attracted men received messages predominately from female peers concerning their talent and themes connected with the arts. The heterosexual men received more of their messages from male peers addressing the topics of sports, recreation, and invitations to engage in shared activities. The research raises questions about the well being of young men who may not identify with most of the dominant images of masculinity available to them. The absence of an adequate cultural script for same-sex attracted youth who must reconcile their sexual feelings with the beliefs of their conservative religious traditions is discussed.

Focusing of strong shock waves in a gas-filled thin test section with various forms of the reflector boundary is investigated. The test section is mounted at the end of the horizontal co-axial shock tube. Two different methods to produce shock waves of various forms are implemented. In the first method the reflector boundary of the test section is exchangeable and four different reflectors are used: a circle, a smooth pentagon, a heptagon and an octagon. It is shown that the form of the converging shock wave is influenced both by the shape of the reflector boundary and by the nonlinear dynamic interaction between the shape of the shock and the propagation velocity of the shock front. Further, the reflected outgoing shock wave is affected by the shape of the reflector through the flow ahead of the shock front. In the second method cylindrical obstacles are placed in the test section at various positions and in various patterns, to create disturbances in the flow that will shape the shock wave. It is shown that it is possible to shape the shock wave in a desired way by means of obstacles. The influence of the supports of the inner body of the co-axial shock tube on the form of the shock is also investigated. A square shaped shock wave is observed close to the center of convergence for the circular and octagonal reflector boundaries but not in any other setups. This square-like shape is believed to be caused by the supports for the inner body. The production of light, as a result of shock convergence, has been preliminary investigated. Flashes of light have been observed during the focusing and reflection process. / QC 20101126

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