Flow induced vibration of flow around a flexible tube array in cross flow are investigated experimentally. The different parameter including velocity, turbulent intensity, and nature frequency of tube. The flow structure and stability between flow and tube are analyzed by flow visualization and flow measurement. Further more, missing tube to find the change of the flow and the influenced of nearby tube, to get the way decreasing the vibration of tube.

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ABSTRACT The flow-induced vibrations of tubes in a rotated triangular array subject to cross flow are investigated numerically and experimentally. The parameters are inlet velocity of cross flow, number of tube, and tube natural frequency. In the study, the instantaneous fluid forces on tube surfaces are computed numerically, the instantaneous displacement of the tubes due to the fluid forces is calculated, and thus the motions of the tubes in cross flow are described. Experiments are also conducted to compare the numerical results. The tube vibrations in a water tunnel are measured by two accelerometers. The amplitudes, spectra, and trace of tube motion are presented. The critical velocities of tube vibrations are then determined. Experimental results show that some tubes vibrate seriously when the flow velocity increases up to a critical value, and hysteresis of the tube vibrations is observed. In case of the seven-tube array, the tubes in the fourth row exhibit the most serious vibration. When the flow velocity is above the critical value, only one dominant frequency of the tube vibrations is detected, comparing to multiple dominant frequencies in subcritical condition. Furthermore, the tube in supercritical condition behaves like a limit cycle, especially when the natural frequency is equal to or near the vortex shedding frequency from the upstream tubes. It is also shown that the critical velocity decreases with more surrounding tubes in the upstream and does not change as more adjacent tubes are added in the downstream. However, the tube number seems to have no effect on the critical velocity when the tube natural frequency is far from the vortex shedding frequency.

In this study, Thermomechanical properties of Ti-50.8 and 50.7 at% Ni alloy severely deformed using Equal Channel Angular Extrusion (ECAE) are investigated. The aim of this study is to reveal the effects of severe plastic deformation on shape memory, pseudelasticity, interplay between plastic deformation via dislocation slip and twinning, and forward and reverse martensitic transformation. The samples are processed at room temperature, i.e. slightly above the austenite finish temperature, and at 450 °C, i.e. well-above the austenite finish temperature. Transformation temperatures, microstructural evolution, and thermomechanical properties of ECAE processed samples are studied before and after low temperature annealing heat treatment and compared with conventional cold drawn and precipitation hardened material. The unique findings are: 1) the observation of a mixture of heavily deformed B2 (austenite) and B19’ (martensite) phases in the samples processed at room temperature although martensite stabilization was expected, 2) the observation of highly organized, twin-related nanograins in B2 phase of the samples deformed at room temperature which was attributed to B2 to B19' via SIM, and B19' to B2 via SPD (SIM: Stress Induced Martensitic transformation, SPD: Severe Plastic Deformation) transformation sequence, 3) simultaneous observation of B2 austenite and strain induced B19’ martensite in the samples deformed at 450 °C, and 4) perfect pseudoelasticity, small pseudoelastic stress hysteresis and excellent cyclic response with no irrecoverable strain up to 1000 cycles for ECAE at 450 °C processed sample. Strain induced martensite in NiTi alloys was reported for the first time. The formation of well-organized twin-related nanograins via severe plastic deformation opens a new opportunity for twinning induced grain boundary engineering in NiTi alloys which significantly improves the matrix strength and the cyclic response against degradation of shape memory and pseudoelasticity.

Plankton communities are important members of the food web in coastal systems and are regulated by top-down and bottom-up controls. This study examined the influence of bottom-up controls, such as physicochemical factors, and top-down controls, such as predation, on the plankton communities in South Bay, Texas. Microalgal photopigments were ascertained by high-performance liquid chromatography (HPLC) to determine the relative abundances of major algal classes. Zooplankters were identified to the lowest possible taxon and enumerated. No spatial trends were observed for the physicochemical factors. The northern bay sections exhibited significantly higher phytoplankton and microphytobenthic diatom biomass, probably due to their proximity to the bay inlet. Copepod, gastropod veliger and brachyuran zoea abundances were also higher in this area, albeit insignificantly. The southern bay sections experienced significantly higher cyanobacterial, euglenophyte and chlorophyte biomass, and polychaete larval abundances. Total zooplankton and nauplii abundances were also higher in the southern areas, albeit insignificantly. Sampling the inaccessible areas of the bay in the future may reveal spatial variability among the physicochemical factors which could be influencing the distribution of plankton. Temporal variation for the physicochemical factors followed a typical trend for subtropical climates and influenced the seasonality of the plankton communities. Phytoplankton biomass peaked in February, August and October but these maximums were not significantly different from the other months sampled. Microphytobenthic biomass peaked during the summer months, while diatom biomass also peaked in February. Zooplankton abundances peaked in October, while nauplii and polychaete larvae also peaked in February. Relationships between wind speed, turbidity and the microalgal pigments were assessed to determine if wind-induced resuspension influenced the location of the major algal classes within the water column compared to the sediments. Wind speed and turbidity were directly related to each other, albeit insignificantly. Some phytoplankton and microphytobenthos were considered tychopelagic because wind-induced resuspension increased their biomass in the water column compared to the sediments. The physicochemical factors exerted bottom-up control of plankton community dynamics in this study, while top-down controls, such as predation, require further investigation. Future studies should focus on which of these controls have more influence on plankton community dynamics in South Bay.

This work is devoted to the study of the quantum coherent effects in diatomic molecular systems by using high resolution laser spectroscopy. In particular, we have studied the rubidium diatomic molecular gaseous medium's absorption spectrum with high resolution single mode laser spectroscopy. The derived electronic and rotational vibrational constants were used in the backward Raman amplification experiment of Rb diatomic molecule. Both experimental results and theoretical calculation confirms that there is strong backward directionally dependent radiation. This effect can further be utilized in remote detection of chemical material. In the saturated spectroscopy experiment of the cesium diatomic molecule, long-lived ground state coherence was observed. The coherence would decay at a rate less than the natural life time of the excited states, which indicates great possibility for performing the quantum optics experiments previously performed in atomic systems only. Electromagnetically induced transparency has been observed in many atomic systems for many years, while it has been seldom realized in molecular systems. In our experiment of electromagnetically induced transparency in cesium diatomic molecules, we utilized  energy levels, and observed subnatural linewidth. This is the first time to realize a  type EIT in a molecular ensemble. This experiment will lead to many other experiments of quantum effects in a molecular system, such like magnetic optical rotation, light storage in ensemble of molecules. Magnetically induced chirality in an atomic ensemble is also investigated in my research.

Claims asserting that abortion harms the mental, physical and emotional health of women have recently gained influence among the judicial and legislative branches of government as well as the general public. While there is a growing body of literature on the place of such women-protective arguments in the contemporary abortion debate, comparatively little has been written on the origins of such claims. This paper traces the role of women-protective claims within the anti-abortion movement from the early nineteenth century to the present, using a variety of primary source material, including medical and scientific texts, legal documents, and lay and popular publications. Special attention is given to the role of physicians in the abortion debate and, accordingly, primary source materials authored by physicians are used extensively. By following these women-protective arguments, this paper shows that while women-protective claims emerged as early as the nineteenth century as part of the first American movement to criminalize abortion, a distinct women-protective strategy was created by anti-abortion activists during the 1980s in an attempt to re-criminalize abortion by both increasing popular resistance to abortion and to posing a legal challenge to Roe v. Wade. In addition, this paper demonstrates that the modern women-protective strategy relied on a depiction of women as helpless victims who needed the government to save them from making their own decisions and restore them to their natural role as mothers.

Thesis (M. Communication Pathology)--University of Pretoria, 2003. / Summary in English and Afrikaans. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Hong Kong, 1985.