The increased demand for liquefied natural gas (LNG) has led to the construction of several new LNG terminals in the United States (US) and around the world. To ensure the safety of the public, consequence modeling is used to estimate the exclusion distances. The purpose of having these exclusion distances is to protect the public from being reached by flammable vapors during a release. For LNG industry, the exclusion zones are determined by the half lower flammability limits (half LFL, 2.5% V/V). Since LNG vapors are heavier‐than‐air when released into atmosphere, it goes through stages, negative, neutral and positive buoyant effect. In this process, it may reach the half LFL. The primary objective of this dissertation is to advance the status of LNG vapor dispersion modeling, especially for complex scenarios (i.e. including obstacle effects). The most used software, box models, cannot assess these complex scenarios. Box models simulate the vapor in a free‐obstacle environment. Due to the advancement in computing, this conservative approach has become questionable. New codes as computational fluid dynamics (CFD) have been proven viable and more efficient than box models. The use of such advance tool in consequence modeling requires the refinement of some of the parameters. In these dissertation, these parameters were identified and refine through a series of field tests at the Brayton Firefighter Training Field (BFTF) as part of the Texas A&M University System (TAMUS). A total of five tests contributed to this dissertation, which three of them were designed and executed by the LNG team of the Mary Kay O'Connor Process Safety Center (MKOPSC) and the financial support from BP Global SPU Gas (BP). The data collected were used as calibration for a commercial CFD code called CFX from ANSYS. Once the CFD code was tuned, it was used in a sensitivity analysis to assess the effects of parameters in the LFL distance and the concentration levels. The dissertation discusses also the validity range for the key parameters.

A central result in price theory is the law of one price: prices of a homogeneous good sold at different locations should be equal. Empirical studies of the law of one price find that it is often violated. In my dissertation I explore the allocation problem that suppliers face when supplying multiple markets. I use the experimental method to examine the effect of an increase in the number of suppliers in a market, ceteris paribus, has on the allocation decisions of market participants. I also use the experimental method to investigate suppliers that are strategic and show that market concentration and transportation costs restrict the supplier’s ability to coordinate on an efficient equilibrium. A strategic supplier takes account his own effect on prices. Strategic supplies face a difficult strategy coordination problem. If they cannot solve it, then an inefficient outcome may result. Coordination failure may result in price dispersion across the markets. Resulting price signals do not inform suppliers who should respond and by how much. Price signals are not sufficient for suppliers to solve the strategy coordination problem. In the experiments, I observe that increasing the quantity of suppliers, that is the Herfindahl index of concentration, in the market will decrease the frequency of the equilibrium strategy to be played, holding other things constant. Increasing the number of firms in a market, ceteris paribus, increases price dispersion and coordination on an efficient market allocation is decreased. The experiments reveal that the ability of suppliers to coordinate is directly correlated with the optimization premium: the expected payoff difference between best responding to an opponents strategy and the payoff to an inferior response. The incentive is greater to best respond when the optimization premium is larger. Coordination at the equilibrium allocation is quicker.

None

Optical add/drop multiplexer (OADM) and optical wavelength cross-connect (WXC) are two key components to enable greater connectivity and flexibility in dense wavelength division multiplexing (DWDM) networks. Fiber Bragg grating (FBG) based components have several inherent advantages such as compact, low-insertion loss, high reflectivity, no-linearity effect, polarization insensitivity and wavelength tunability. We experimentally investigate the system power penalty induced by the chromatic dispersion of the FBG as a function of the wavelength detuning of the reflection spectrum for 10 Gb/s signals, which was reflected by cascade of FBGs. Such power penalty limits the number of cascaded gratings and restricts the allowable range of wavelength detuning. In our experiments, we have used several FBG filters with 3-dB bandwidth of 0.43 nm. According to the experimental results, power penalty increases from the central wavelength to the edge wavelength of the reflection spectrum. There are 0.4 dB and 7 dB power penalty for one single FBG and ten cascaded-FBG filter, respectively, when the central wavelength was detuned to ¡Ó0.2 nm and ¡V0.1/+0.14 nm. This study result may give a design guideline of fiber grating-based optical add-drop multiplexers or optical wavelength cross-connects in DWDM nodes.

As the photonic crystal fibers (PCFs) are fabricated, it is hard to modulate their optical characteristics to function as tunable optical devices. To introduce tunable optical characteristics into the PCF structures, one can infiltrate liquids into the air holes of the PCFs to form the liquid-filled PCFs. However, the propagation losses become larger due to the finite liquid-hole layers and the lossy liquids infused in all the air holes of the cladding. In this thesis, an efficient full-vector finite-difference frequency-domain (FDFD) mode solver cooperated with the PMLs is utilized to investigate the propagation characteristics of the selectively liquid-filled PCFs. The propagation constants and the propagation losses of the guided modes on the selectively liquid-filled PCFs can be successfully obtained. From our numerical results, the propagation losses of both the internally liquid-filled PCFs and externally liquid-filled PCFs can be efficiently reduced by the outer or inner air-hole layers, and the useful tunablility characteristics for optical device applications can be maintained. Besides, the dispersion-related devices based on the selectively liquid-filled PCFs are also investigated. It is demonstrated that a DFPCF with the flatten dispersion value D within 0 ¡Ó 1 ps/nm/km over £f = 1.45 £gm to 1.65 £gm or a DCPCF with a high negative dispersion value D = -3100 ps/nm/km at £f = 1.55 £gm can be achieved by infiltrating the liquid into all air holes or specified air-hole layers. In the experiment, a simple selectively blocking technique using the microscopy, the tool fiber and the alignment technique is employed to fabricate the internally and externally liquid-filled PCFs. The measurement of the optical characteristics of these selectively liquid-filled PCFs is carried out and compared with the simulation results.

Extr. de--Uppsala (Suède)--Université d'Uppsala, 2000. / Bibliogr. p. 73-79.

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 102-107).

Thesis (M.S.)--Florida State University, 2003. / Advisor: Dr. Ravindran Chella, Florida State University, FAMU-FSU College of Engineering, Dept. of Chemical Engineering. Title and description from dissertation home page (viewed Sept. 26, 2003). Includes bibliographical references.

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The effect of dispersing discreet periclase (magnesium oxide) or brookite (titanium oxide) nanoparticles into poly(1-trimethylsilyl-1-propyne) (i.e., a super glassy polymer) and 1,2-polybutadiene (i.e., a rubbery polymer) has been examined. Particle dispersion has been investigated using atomic force microscopy and transmission electron microscopy to determine particle/aggregate size and distribution. Titanium dioxide nanoparticles dispersed into aggregates on the order of nanometers, as did magnesium oxide in 1,2-polybutadiene. However, the magnesium oxide filled poly(1-trimethylsilyl-1-propyne) did not exhibit nanoparticle aggregates below approximately one micron in characteristic dimensions. Nanocomposite transport properties were studied, where permeability and solubility coefficients were determined for light gases with increasing pressure, and diffusion coefficients were calculated from the solution-diffusion model. The permeability of light gases in the heterogeneous films increased with increasing particle loading. Depending on particle loading, brookite filled nanocomposite light gas permeability increased to over four times that of the unfilled polymer, whereas at high periclase loadings the nanocomposites exhibited light gas permeabilities in excess of an order of magnitude higher than the unfilled materials. Even at these high loadings the light gas selectivities were higher than predicted for films containing transmembrane defects. Solubility was relatively unaffected by the void volume concentration, although it did increase to some extent depending on the nanoparticle concentration. Wide angle X-ray diffraction, nuclear magnetic resonance, and Fourier transform infra-red experiments were used to determine if the nanoparticles remained stable during film preparation. TiO₂ nanoparticles did not appear to react with water, the polymer matrixes or test gases used in this research. However, under certain circumstances, periclase reacted with adventitious water to form brucite. A desilylation reaction occurred when brucite was exposed to polymers or small molecule compounds that contained a trimethylsilyl group attached to a conjugated organic backbone. This reaction caused certain disubstituted polyacetylenes to become insoluble in common organic solvents.