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The extent of work related fatal accidents has been analysed statistically by agencies throughout the world. As a result of this analysis there is a wealth of information available categorised by industry types, sub-industry, occupation, sex, age, nature of occurrence, bodily location, agency of occurrence and mechanism of injury. It is however extremely difficult to identify information pertaining to confined space fatalities such as contributory factors, mechanisms of injury and other data of an epidemiological nature.

This thesis presents numerical investigations of two-dimensional single-phase turbulent jets and bubbly mixing layers using Reynolds-Averaged Navier-Stokes (RANS) equations. The behavior of a turbulent jet confined in a channel depends on the Reynolds number and geometry of the channel which is given by the expansion ratio (channel width to jet thickness) and offset ratio (eccentricity of the jet entrance). Steady solutions to the RANS equations for a two-dimensional turbulent jet injected in the middle of a channel have been obtained. When no entrainment from the channel base is allowed, the flow is asymmetric for a wide range of expansion ratio at high Reynolds number. The jet attaches to one of the channel side walls. The attachment length increases linearly with the channel width for fixed value of Reynolds number. The attachment length is also found to be independent of the (turbulent) jet Reynolds number for fixed expansion ratio. By simulating half of the channel and imposing symmetry, we can construct a steady symmetric solution to the RANS equations. This implies that there are possibly two solutions to the steady RANS equations, one is symmetric but unstable, and the other solution is asymmetric (the jet attaches to one of the side walls) but stable. A symmetric solution is also obtained if entrainment from jet exit plane is permitted. Fearn et al. (Journal of Fluid Mechanics, vol. 121, 1990) studied the laminar problem, and showed that the flow asymmetry of a symmetric expansion arises at a symmetry-breaking bifurcation as the jet Reynolds number is increased from zero. In the present study the Reynolds number is high and the jet is turbulent. Therefore, a symmetry-breaking bifurcation parameter might be the level of entrainment or expansion ratio. The two-dimensional turbulent bubbly mixing layer, which is a multiphase problem, is investigated using RANS based models. Available experimental data show that the spreading rate of turbulent bubbly mixing layers is greater than that of the corresponding single phase flow. The presence of bubbles also increases the turbulence level. The global structure of the flow proved to be sensitive to the void fraction. The present RANS simulations predict this behavior, but different turbulence models give different spreading rates. There is a significant difference in turbulence kinetic energy between numerical predictions and experimental data. The models tested include 𝘬—𝜖, shear-stress transport (SST), and Reynolds stress transport (SSG) models. All tested turbulence models under predict the spreading rate of the bubbly mixing layer, even though they accurately predict the spreading rate for single phase flow. The best predictions are obtained by using SST model. / Master of Science

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Detonation diffraction has been, and remains, an active area of research. However, detonation diffraction into a confined volume, and specifically the transformation of a planar detonation into a cylindrical detonation, is an area which has received little attention. Experimental work needs to be conducted on detonation diffraction into a confined volume to better understand how the interaction of the diffracted shock wave with a confining wall impacts the detonation diffraction process. Therefore, a facility was constructed to study this problem, and experiments were conducted to determine under what conditions a planar detonation could be successfully transformed into a cylindrical detonation. Four different fuel-oxidizer mixtures, C₂H₂+ 2.5 O₂, C₂H₂+ 4 O₂, C₂H₄+ 3 O₂ and H₂+ 0.5 O₂, were tested in this study using a combination of pressure transducers and soot foil records as diagnostics. Three different regimes of successful transmission; spontaneous re-ignition, continuous reflected re-initiation, and discontinuous reflected re-initiation, were identified. The detonation cell size and the distance from the tube exit to the confining wall, or gap size, were determined to be the most important parameters in the transmission process and a linear correlation for determining whether or not transmission will be successful for a given set of initial conditions was developed for gap sizes between 10 and 35 mm. For gap sizes smaller than 10 mm or gap size larger than 35 mm the linear correlation does not apply. Finally, the results of this study are compared to results on detonation diffraction into a confined volume available in the literature and explanations for any disagreements are given. This study showed that when compared to transmission of a detonation into an unconfined volume, the transmission of a detonation into a confined volume, for the majority of gap sizes, is possible for a wider range of conditions. However, for extremely small gap sizes, when compared to transmission into an unconfined volume, the range of conditions for which successful transmission is possible into a confined volume is actually narrower.

Water is a continuous source of fascination to scientist because of its many counterintuitive low-temperature properties. Although the stable from of water at low temperature is crystalline, liquid water can also exist below the melting point. Many people study the interesting phenomenon of water at low temperature and it is found that two critical points may even coexist in a single component liquid [1]. The other properties of water, like melting point, viscosity, compressibility, self-diffusion constant have also been studied below low temperature [2-4]. Now, we want to take the advantage of the equipment we have in our laboratory to measure the temperature dependence of Cp of water confined in different scale of nano-pores. This is also the beginning for people to study the thermodynamic properties of water confined in nano-pores. In addition, I have learned a lot, such as to understand LabView graphical programming language, the skill to measure AC specific heat, DSC specific heat, and to set up TGA. It will be helpful for me in the future, I think.

In this thesis, we investigate the optical properties of m-plane InGaN/GaN multiple quantum well grown by metal organic vapor phase epitaxy. The optical spectroscopies we employed are photoluminescence (PL), polarized PL, power-dependent PL, photoluminescence excitation (PLE), polarized PLE, and Raman scattering. From the blue shift of E2 mode in Raman spectrum, we find that the epitaxial layers are under compressive stress. The PL spectrum at 10 K is dominated by the emission band peaked at 433 nm. We found the optical emission possesses the polarization anisotropy. The degree of polarization is about 80% at room temperature. It is found that the degree of polarization decreases with increasing temperature, which may be explained by carrier population effect. In addition, two major contributions to the PLE spectrum detected for the emission band have identified. Finally, the absence of quantum confined Stark effect is confirmed by power-dependent PL measurements.

This thesis deals with several aspects of the structure and dynamics of water molecules confined in nanoscopic pores. Water molecules confined in hydrophobic nanocavities exhibit unusual structural and dynamic properties. Confining walls of single-wall carbon nanotubes (SWCNTs) promote strong inter-water hydrogen bonding which in turn leads to several novel structural, dynamic and thermodynamic features not found in bulk water. Confined water molecules form ordered hydrogen-bonded networks, exhibit exceptionally high flow rates as compared to conventional flow in pipes, allow fast proton conduction and exhibit various other anomalous properties. Proteins are known to exploit some of the properties of confined water to perform certain physiological functions. Various properties of confined water can also be exploited in the design of nanofludic devices such as those for desalination and flow sensors. In addition, water molecules confined in SWCNTs and near graphene sheets serve as model systems to study various effects of confinement on the properties of liquids. In this thesis, we present the results of detailed molecular dynamics simulation studies of confined water molecules. In chapter 1, we summarize the findings of existing simulations and experimental studies of bulk and confined water molecules. We also highlight the significance of studying the structure and dynamics of confined water molecules in biological and biotechnological applications. Chapter 2 provides a brief ac-count of the methods and techniques used to perform the simulations described in subsequent chapters of the thesis. We also present a brief overview of the methods used to extract physical properties of water molecules from simulation data, with emphasis on the Two Phase Thermodynamics (2PT) method which we have used to compute the entropy of confined and bulk water molecules. In chapter 3, we discuss the thermodynamics of water entry in SWCNTs of various diameters. Experiments and computer simulations demonstrate that water spontaneously fills the interior of a carbon nanotube. Given the hydrophobic nature of the interior of carbon nanotubes and the strong confinement produced by narrow nanotubes, the spontaneous entry of water molecules in the pores of such nanotubes is surprising. To gain a quantitative thermodynamic understanding of this phenomenon, we use the recently developed Two Phase Thermodynamics (2PT) method to compute translational and rotational entropies of water molecules confined in SWCNTs and show that the increase in energy of a water molecule inside the nanotube is compensated by the gain in its rotational entropy. The confined water is in equilibrium with the bulk water and the Helmholtz free energy per water molecule of confined water is the same as that in the bulk within the accuracy of the simulation results. A comparison of translational and rotational spectra of water molecules confined in carbon nanotubes with those of bulk water shows significant shifts in the positions of spectral peaks that are directly related to the tube radius. These peaks are experimentally accessible and can be used to characterize water dynamics from spectroscopy experiments. We have also computed the free-energy transfer when a bulk water molecule enters a SWCNT for various temperatures and carbon-water interactions. We show that for reduced carbon-oxygen interaction, the free energy transfer is unfavourable and the SWCNT remains unoccupied for significant periods of time. As the temperature is increased, the free energy of confined water becomes unfavourable and reduced occupancy of water is observed. Bulk water exhibits many anomalous properties. No single water model is able to reproduce all properties of bulk water. Different empirical water models have been developed to reproduce different properties of water. In chapter 4, a comparative study of the structure, dynamics and thermodynamic proper-ties of water molecules confined in narrow SWCNTs, obtained from simulations using several water models including polarizable ones, is presented. We show that the inclusion of polarizability quantitatively affects the nature of hydro-gen bonding which governs different properties of water molecules. The SPC/E water model is shown to reproduce results in close agreement with those from polarizable water models with much less computational cost. In chapter 5, we report results obtained from simulations of the properties of water confined in the space between two planar surfaces. We consider three cases: two graphene surfaces, two Boron Nitride (BN) surfaces and one graphene and one BN surface. This is the first detailed study of the behaviour of water near extended BN surfaces. We show that the hydrophilic nature of the BN surface leads to several interesting effects on the dynamics of water molecules near it. We have observed a change in the activation energy, extracted from the temperature dependence of the translational and rotational dynamics, near 280K. This change in activation energy coincides with a change in the structure of the confined sheet of water, indicated by a sudden change in energy. We have also found signatures of glassy dynamics at low temperatures for all three cases, the glassy effects being the strongest for water molecules confined between two BN sheets. These results are similar to those of earlier studies in which novel phases of water have been found for water molecules confined between other surfaces at high pressure. In chapter 6, we have described our observation of a novel phenomenon exhibited by water molecules flowing through a SWCNT under a pressure gradient. We have shown that the flow induces changes in the orientation of the water molecules flowing through the nanotube. In particular, the dipole moments of the water molecules inside the nanotube get aligned along the axis of the nanotube under the effect of the flow. With increasing flow velocities, the net dipole moment first increases and eventually saturates to a constant value. This behaviour is similar to the Langevin theory of paramagnetism with the flow velocity acting as an effective aligning field. Preferential entry of water molecules with dipole moments pointing inward is shown to be the main cause of this effect. This observation provides a way to control the dipolar alignment of water molecules inside nano-channels, with possible applications in nanofluidic devices. Chapter 7 contains a summary of our main results and a few concluding re-marks.

The purpose of this study was to examine whether cognitive-behavioral therapy could be effective in alleviating depression in mildly mentally retarded or borderline intelligence individuals. It was hoped this would prove to be a viable alternative or adjunct to medical interventions in treating depression with this population. Subjects participated in one of two cognitive-behavioral groups for 12 weeks. Two other treatments (two exercise and two structured, talk-oriented groups) served as control groups; these group members had the same daily routine as individuals in the treatment group. Control group subjects were also administered the same pre- and post-test. Seventy-three subjects were referred to participate, all on a volunteer basis. Subjects resided at the Stockton Developmental Center. All subjects were at the Center involuntarily, with 39 percent committed to the Center due to penal code violations. The Beck Depression Inventory (BDI) was used as a pre-screening device, and subjects scoring in the clinical ranges of depression on the BDI were included in the study. Fifty-eight subjects met pre-screening criteria and were included. Based on BDI scores, subjects were assigned to one of three ranges of depression specified for the BDI. Subjects in each range were then matched on BDI scores and randomly assigned to the treatment groups. The pre- and post-test measure was the Emotional Problems Scales, which include both a personality inventory with questions answered by each individual and a behavior rating scale answered by the individual's primary counselor. Scores on depression and related scales were examined through the multivariate analysis of variance procedure. Forty-nine subjects were included in the final statistical analysis. There was no significant finding across groups for a decrease in depression or for other variables. No treatment proved more effective than any other. An examination of subject characteristics for those demonstrating the highest levels of improvement following treatment found that subjects with scores initially in the extremely severe range on depression were most likely to evidence change in a positive direction. Those who demonstrated improvement in the cognitive-behavioral groups tended to have IQ's over 62.

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