For the purpose of fire analysis and fire safety engineering, the development of empirical correlations for major species yields in compartment fires has become an important priority due to the inability to calculate these quantities from first principles. Studies of simplified upper layer environments have shown that major species production rates can be correlated with the equivalence ratio in what is known as the Global Equivalence Ratio concept (GER). Due to the simplification in these past experiments, it was not known if the GER concept was valid for compartment fires. Therefore, there was a need to determine if correlations existed between major species yields and the equivalence ratio for actual compartment fires. Since the flow of toxic gases from a room poses a hazard to building occupants, it was also important to determine if correlations for CO yield outside of a compartment on fire exist, particularly when external burning occurs. A 2.2 m³ test compartment was used to investigate the burning of four fuels (hexane, PMMA, spruce and flexible polyurethane foam) in compartment fires. The test compartment was specially designed with a two-ventilation path system which allowed the direct measurement of the plume equivalence ratio (the ratio of the fuel volatilization rate to the air entrainment rate normalized by the stoichiometric fuel-to-air ratio). Empirical correlations between the upper layer yield of major species and the plume equivalence ratio were shown to exist The results reveal that the production of CO is primarily dependent on the compartment flow dynamics (i.e., the equivalence ratio) and upper layer temperature. A chemical kinetics study indicated that increased compartment temperature affects upper layer species yields in two ways 1) the generation of species in the plume is changed and 2} oxidation of post-flame gases in the layer is affected. The correlations developed in the compartment fifes were qualitatively similar to those developed by Beyler for simplified upper layer environments. However, quantitative differences existed and are explained by the temperature effect. The species yields downstream of hexane compartment flues were investigated and compared to upper layer yields. Results showed that downstream CO yields can be correlated to the plume equivalence ratio when taking into account the occurrence of external burning. When sustained external buning occurred for equivalence ratios greater than 1.7, downstream CO yields were reduced to 10 to 25 percent of the upper layer value. Results are very encouraging in indicating that an ignition criterion based on lean flammability limits is useful in predicting the flammability of upper layer gases in compartment fires. An ignition index value of 1.3 indicated the occurrence of sustained external burning and, thus, a reduction of CO, for the hexane fires studied. / Ph. D.

This study proposes an improved methodology for solving the semi-controlled ventilation network problem. After analysis and consideration of the objective and legal, technical and operation convenience factors, the semi-controlled network problem is formulated through a nonlinear nonconvex programming model. Using the special ordered sets variables, the nonconvex problem is linearized and then optimized by the modified branch and bound procedure where the automatic interpolation technique is used to improve the accuracy to which the each nonlinear function is approximated. The global optimality of the methodology is on the computational the~ry basis. And the applicability of the methodology to the generalized ventilation problem is investigated, and it is demonstrated with a number of examples. This study also compares the several methods which have been used so far to optimize the underground ventilation networks. / Ph. D.

Compressible turbulence in a high-speed, high Reynolds number, supersonic free shear layer was studied. A two-dimensional free mixing layer was chosen to study turbulence rather than a wall bounded flow due to the experimental fact that the effects of compressibility become significant at lower Mach numbers. The mixing layer was generated by supersonic injection of air (M_s = 1.8, P_ts = 0.5 atm. T_ts= 295K. and Re/m = 7x10⁶) through a rearward facing tangential slot, into a supersonic free stream (M_∞ = 4.0, P_t∞ = 12.5 atm, T_t∞ = 290K, and Re/m = 70x10⁶). Flow visualization was accomplished by nanosecond Shadowgraph photography. The overall flow structure was documented with the Shadowgraph and conventional mean flow probes (Pitot pressure, cone-static pressure, and thermocouple probes). The turbulent structure of the flow field was also clearly depicted in the Shadowgraphs. Image processing techniques were developed in order to determine root-mean-square index of refraction (density) fluctuation levels from the Shadowgraph plates. Multiple overheat normal and cross-wire techniques were developed and/or improved for this study. The present research concentrated on the Reynolds averaged form of the Navier-Stokes equations. where the effects of compressibility are manifested through "apparent mass" terms (i.e. p′u′_i). These terms appear in all of the Reynolds averaged Navier-Stokes equations (continuity, momentum, and energy). A new turbulence transformation, coupled with innovative experimental methods. allowed the full compressible Reynolds shear stress (the typical incompressible term, pu′_iu′_j as well as the apparent mass terms) to be directly measured. The full compressible heat flux and apparent mass terms were also estimated from the cross-wire results. Profiles were obtained at four downstream stations which were strategically located to map different levels of development of the shear flow. The first station was very close to the injector, about one free stream boundary layer thickness downstream (x/δ_∞ ≈ 1), hence, it is in the initial region. The second station was located at x/δ_∞ ≈ 28, which was near the beginning of the fully developed zone. The third station, x/δ_∞ = 83, was just prior the shear layer and floor boundary layer merging. The last station was positioned just aft of the layer merging, x/δ_∞ = 106. Reynolds averaging of the compressible Navier-Stokes equations implies that the compressible turbulence affects all of the governing equations. It was found, experimentally, that the effects of compressibility on turbulence were more than significant accounting for about 75% of the total level of the Reynolds shear stress formulation for the present study (i.e. the apparent mass term multiplied by the axial velocity was about 3-4 times the typical incompressible shear term). For the present mean adiabatic flow, the compressible turbulence accounted for 100% of the turbulent heat flux. The apparent mass in the continuity equation was, by definition, only due to compressibility. These results led to the development of anew Compressible Apparent Mass Mixing Length Extension (CAMMLE) model that accounts for compressible turbulence in all of the governing equations (i.e. the turbulence terms in the continuity, momentum, and energy were all consistently formulated). The CAMMLE formulation is a generalization of the Situ-Schetz compressible mixing length formulation, which was developed to account for the apparent mass terms in the momentum equation. A total of seven turbulence models were experimentally evaluated, the CAMMLE model, the Prandtl incompressible and the Situ-Schetz compressible mixing length models, the Prandtl and Bradshaw turbulent kinetic energy (TKE) formulations, and two compressible TKE extensions that are based upon a newly defined compressible TKE formulation. The measured turbulence data was used to assess the various models, where the measured mean flow profiles were used in the model formulations. The incompressible formulations were generally successful in representing the measured incompressible part of the Reynolds shear stress. However, this term only accounted for about 25% of the total shear stress level. All of the compressible extensions provided accurate estimates of the full compressible Reynolds shear stress. In addition, the newly developed CAMMLE model was also successful in representing the apparent mass terms in the continuity equation. The CAMMLE model was also the only formulation to accurately predict the measured compressible turbulent heat flux in the energy equation. The CAMMLE, Situ-Schetz, and Prandtl incompressible mixing length models were all incorporated in to a 3-D finite volume Navier-Stokes code (GASP 2.0). The numerical simulations indicated that the new compressible apparent mass mixing length extension performed very well. The CFD results also enlightened a misuse with all of the current compressible turbulence models. With the exception of the new apparent mass formulation, all existing turbulence models neglect the compressible turbulence effects on the continuity equation and treat the energy equation in an ad hoc effective eddy viscosity and thermal conductivity fashion. The numerical and theoretical studies indicated that this led to poor prediction of the mixing layer width for cases where the free stream Mach number was significantly higher than the injection Mach number. / Ph. D.

Supercritical fluid extraction (SFE) is becoming an attractive alternative to conventional solvent extraction for many reasons. These reasons include advantages of speed, the ability to be automated more easily than conventional solvent extractions and the lack of solvent disposal after the extraction has been performed. At this date SFE is performed in a multitude of ways with no one method out performing the others. The different ways in which SFE is performed is reviewed. Supercritical fluid extraction of analytes from aqueous solution has not received much attention. The design of a system which allows for the extraction of analytes from aqueous solution has been explored in this thesis. Several related areas (injection techniques for supercritical fluid chromatography and on-line SFE) were also developed. The injection port of a supercritical fluid chromatograph was modified to provide better ( more reproducible) sample introduction. For a 100 ppm 3,5-nitrobenzamide solution in methylene chloride the area reproducibility was increased from 3.2% RSD for the unmodified valve to 0.74% RSD for the modified valve. The method also resulted in a more narrow solvent front as well as an increase of 10% in the number of theoretical plates of the system. On-line SFE\SFC was explored as one possible configuration for the extraction of analytes from aqueous solution. Solvent elimination injection (SEI), was developed for SFC. The difference in vapor pressure between the analytes and solvent allowed for the solvent to evaporate and be transported form the system while the analytes were collected on various traps. After evaporation of the injection solvent the analytes were flushed onto a chromatographic column. SEI allowed for the reproducible injection of larger volumes of sample (solvent and analyte) into the system. SEI allowed for different hardware configurations to be tested without performing an actual supercritical fluid extraction. An off-line solid phase trapping system for SFE was developed. The system trapped the analytes from the SFE effluent onto a solid phase extraction cartridge. The cartridge could then be rinsed in a normal fashion to elute the analytes of interest. Trapping in this way was found to allow for faster extraction rates than liquid trapping. The efficiency of the trapping mechanism was found to be dependent upon the temperature of the trap, the chemical functionality of the phase bonded io the silica and the nature of the analytes. A system which allowed for the extraction of moderate volumes (3-5 mL) of aqueous solution was developed. A test solution of phenols was used to evaluate the system. The extractability of the phenols was found to be a function of pressure of the system and the chemical nature of the phenol. A decrease in extractability of the phenols was found to take place at pressures greater than 250 atm. The distribution coefficient of phenol was found to increase steadily through 400 atm. A decrease in surface area of the supercritica1 fluid passing through the aqueous solution was thought to be responsible for the apparent contradiction in behavior. / Ph. D.

This dissertation seeks to investigate empirically the determinants and implications of large block shareholdings. Specifically, it attempts to answer the following questions : (1) Why do some firms have blocks and others not ? (2) What are the valuation consequences of large block creations ? (3) What are the cross-sectional relationships between the market response and characteristics of the firm and of the blockholder ? and, finally, (4) What are the time series (and control-firm-adjusted) changes in firm performance measures and operating variables attributable to large shareholder monitoring ? The above questions are addressed by recognizing, firstly, that the incidence of large block shareholdings is rational only when the gains from a blockholding exceed the costs of foregone diversification-of-portfolio opportunities. The potential sources of gains to the blockholder are identified as resulting from firm-value-increasing reductions in the agency costs of free cash flow and other non-free-cash-flow-related equity agency costs, equity-value-increasing potential for wealth transfers from bondholders, firm-value-increasing expectation of synergy gains in the case of corporate blockholdings, as well as equity-value-reducing gains such as the potential for insider trading, and the expectation of a greenmail premium. It is hypothesized that the net valuation impact of these gains to the blockholder is positive. Event study results support this hypothesis. Cross-sectional regression results suggest that announcement period abnormal returns are reliably explained by the potential for wealth transfers from bondholders, as proxied by the level of discretionary assets in the firm. Further, consistent with theory, announcement excess returns are positively related to the size of the blockholding and the identity of the blockholder. There is no evidence that blockholders play a valuable role in limiting managerial discretion over free cash flow. Firm-specific risk also appears to have no valuation impact; this suggests that the potential benefits from blockholder monitoring may be offset by the potential costs resulting from insider trading. Finally, a pre- and post-block matched-pair comparison of key performance measures and operating variables between the sets of sample firms and control firms provides weak support for the monitoring role of the large block shareholder. A time-series tracing of blockholder affiliation with the target firms reveals that in only a small fraction of firms does the blockholder obtain a seat on the target firm’s board of directors - a virtual requirement for effective monitoring to occur. Overall, these findings do not support theoretical arguments that envisage blockholder monitoring as a long-term incentive-alignment mechanism between managers and shareholders. / Ph. D.

The purpose of this study was to explore and understand the nature of marriage and family therapy supervision from the perspectives of supervisors and supervisees. Two supervisors and four supervisees in an AAMFT-approved doctoral program participated in in-depth interviews focusing on their previously recorded supervision sessions. Results indicate that supervisees and supervisors tend to punctuate their experiences in supervision along an intersecting continuum of role and relationship. Supervisees experienced a high degree of anxiety during supervision and were particularly concerned with the issue of dual roles. Supervisors experienced themselves as empowering the supervisees to awaken to their own potential and avoid being viewed in an all-knowing position. / Ph. D.

This dissertation presents a discussion of the asymptotic behavior and estimation structure of the H_∞ central controllers in terms of the well-known behavior of the LQG controller and gives some insight into the physics of the H_∞ controller that is often presented in an unclear manner in the current literature. The connections to LQ game theory that underlie this confusion are discussed. Augmented systems that are typically used in disturbance rejection problems are also analyzed. Additionally, a controlled output equation for disturbance rejection is developed based on the physics of the problem rather than the typical ad hoc approaches of the past. These controlled output equations are also appropriate for LQG compensators. In order to verify the proposed approach, an experiment in harmonic and narrowband disturbance rejection using a simply supported steel plate is presented. Discrete-time LQG, and continuous-time H_∞ and LQG controllers that have been transformed to discrete-time are used to determine the attainable performance of each approach. The results indicate that the H_∞ controller provides more damping than either LQG approach and that discrete-time design procedures are necessary for maximum disturbance rejection. / Ph. D.

Lead zirconate titanate (PZT) is a ferroelectric material which has many interesting properties. Recently, PZT thin films have been considered as one of the most promising materials for the application of nonvolatile electronic memories. In this study, a sol-gel process for PZT film preparation was adopted and greatly modified. PZT films with very desirable electrical properties have been successfully prepared by this modified sol-gel process. One of the problems of incorporating PZT films into the DRAM devices is the need of high post-deposition annealing temperatures which complicates their integration into the existing semiconductor manufacturing process. In this work, formation kinetics of PZT films were studied and the nucleation was found to be the rate-limiting step in the formation of the perovskite phase. Based on this finding, a seeding process was invented to encourage the nucleation of the perovskite phase. As a result of this seeding process, the transformation temperature has been lowered by as much as 100°C. The seeded PZT films also have good ferroelectric properties. The ferroelectric domain structures, and the metastable pyrochlore phase including its transformation to the perovskite phase have been investigated by transmission electron microscopy (TEM). The domain structures of the PZT films had the {lID} <110> orientation and most of them were 90° domains. The TEM study of the pyrochlore to perovskite transformation provides valuable insight on the formation of the perovskite phase. Among all the processing steps, the drying process of the sol-gel films created the highest growth stress. In addition, the thin film stress study was also used to determine the transformation stress and Curie temperature. The effects of composition, thermal processing conditions, and film thickness on electrical properties have been studied. Some of the notable results are as follow: (1) PZT films with a Zr/Ti ratio of 53/47, the morphotropic boundary (MPB) composition, have the highest remanent polarization and the lowest coercive field. (2) The optimum annealing temperatures for most of the PZT compositions are found to be about 50°C higher than the completion temperature of the perovskite formation (T_c^per) of the same composition. (3) PZT films with film thicknesses greater than or equal to 170 nm have electrical properties very close to those of the thicker films and are not susceptible to dielectric breakdown at an applied voltage of 5 V. / Ph. D.

The advent of new methods to detect animal drug residues has resulted in a need to independently validate them. The effects of processing milk on the performance of these methods was evaluated. Antibiotic-free milk samples were spiked with sulfamethazine, penicillin G, and chlortetracycline at levels of 10, 10 and 30 ppb, respectively. Spiked milk and negative control milk was heat-treated, homogenized or heat-treated and homogenized. The procedures evaluated for penicillin detection were Bacillus stearothermophilus disk assay, a HPLC described by Barker et al., Charm II microbial receptor assay, and CITE Probe and LacTek enzyme immunoassays. The procedures evaluated for sulfonamide detection were an HPLC method described by Long et al., Charm II microbial receptor assay, CITE Probe, LacTek and Signal enzyme immunoassays. The methods evaluated for tetracycline detection were a HPLC method described by Long et al., Charm II microbial receptor assay, and LacTek and CITE Probe enzyme immunoassays. The results indicate that the commercial tests and the disk assay were not adversely affected by processing treatments. Significant treatment differences were found when testing raw Charm II data by analysis of variance but these differences did not effect the overall results of the test. Results of the HPLC method were inconclusive for the three drugs tested. / Master of Science

As immiscible organic contaminants migrate through the subsurface environment, a significant portion of non-aqueous phase liquids (NAPL's) is trapped by capillary forces and remains in the subsurface as immobile blobs or ganglia. Residual saturations of NAPL on the order of 5-30 percent have been observed in saturated subsurface systems. The NAPL can partition into the aqueous phase and serve as a long-term source of groundwater contamination. NAPL-aqueous mass transfer rates impact the distribution and the rate of movement of the contaminant within the subsurface. The mass transfer coefficient is a function of many variables including aqueous phase velocity and NAPL-aqueous interfacial area. A one-dimensional column apparatus and experimental procedure was developed to study the nature of mass transfer between the aqueous phase (water), and a non-aqueous phase liquid (NAPL) in porous media. The NAPLs used in the experiments were composed of soluble and insoluble (inert) compounds. These experiments were designed to investigate the aqueous mass transfer of benzene, toluene, ethylbenzene, and xylene from and inert compound (soltrol or hexadecane). The results of this research indicate that the rate of NAPL-aqueous interphase mass transfer increases as a function of increasing aqueous phase velocity and percent NAPL saturation. Miller's equation was used to compare the model performance. Comparison of the experimental K values obtained by the literature was performed. The results indicated a satisfactory model performance. / Master of Science