Solid propellant research has mainly been directed towards more accurate characterization of the propellant material nature and more reliable structural analysis of the grain. Internal star grain design is among the most popular grain shapes that are used in today's propulsion system. Due to its complex geometry, stress concentrations are inevitably present around the highly curved area. Furthermore, this geometric effect together with various loading conditions throughout the grain's service life actually causes numerous defects inside its body. However, little is known concerning the three-dimensional fracture mechanism of the surface cracks which are the most common defects detected in the real rocket motor grain. After a brief evaluation of the current status of solid propellant research, stress analysis of a star grain model under internal pressure was performed by both photoelastic experiments and finite element calculations. These results illustrated the stress concentration effect around the star finger tip in addition to the global stress distribution across the whole section. Meanwhile, the deformation of the grain's outer surface was also obtained from the finite element results. A series of photoelastic experiments was conducted on cracked specimens with surface flaws emanating both on and off the axis of symmetry starting from the star finger tip. For the symmetric crack problem, cracks with different depths were intensively studied and the three-dimensional stress intensity factor (SIF) distribution was obtained for each test. These experimental data were further used to construct three analytical models, the "equivalent" radius model, the weight function model and the notch-root crack model, to expand the application range of the experimental data base so that a symmetric crack's SIF distribution with an arbitrary depth can be predicted. Moreover, surface cracks initiated off the axis of symmetry were also investigated by considering two off-axis angles. The crack shape and propagation path were achieved through a series of experiments and two methods were developed to effectively predict the possible crack growth path under sufficient pressure. The SIF distribution around the crack border was obtained for different offaxis angles and the factors that might influence the distributions were addressed based on the comparisons between the symmetric and asymmetric cracks, and the asymmetric cracks with different geometries. / Ph. D.

Strategies for topology optimization of trusses and plane stress domains for minimum weight subject to stress and displacement constraints by Simultaneous Analysis and Design (SAND) are considered. The ground structure approach is used. For the truss topology optimization, a penalty function formulation of SAND is compared with an augmented Lagrangian formulation. The efficiency of SAND in handling combinations of general constraints for truss topology optimization is tested. A strategy for obtaining an optimal topology by minimizing the compliance of the truss is compared with a direct weight minimization solution to satisfy stress and displacement constraints. It is shown that for some problems, starting from the ground structure and using SAND is better than starting from a minimum compliance topology design and optimizing only the cross sections for minimum weight under stress and displacement constraints. One case where the SAND approach could not predict a singular topology obtained by compliance minimization is discussed in detail. A member elimination strategy to save CPU time is developed. For the plane stress topology optimization problem, the ground structure is obtained by using 3 noded constant stress triangular elements. A chess board pattern is observed in the optimal topologies which may be attributed to the triangular elements. Some suggestions for future research are made. / Ph. D.

The plsX50 mutation is required together with plsX26 (encoding a K_m- defective glycerol 3-phosphate acyltransferase) for the conferral of a glycerol 3- phosphate auxotrophic phenotype. A 4.9 kb segment of DNA complementing the plsX50 mutation have been cloned and sequenced. Six open reading frames (ORF’s) were found with five reading in the same direction and one in the opposite direction relative to the plsX gene. Each ORF encoded a protein, as demonstrated by radiolabeling in maxicells. ORF1 (orfY) encodes a protein of unknown function. ORF2 and ORF3 (rpmF) were sequenced prior to this study and encode a protein called G30k of unknown function and L32, a protein of the large ribosomal subunit, respectively. ORF4 complemented the p/sX50 mutation. ORFS was identified as fabH encoding 3-ketoacyl-ACP synthase III. ORF6 was identified as fabD encoding malonyl-CoA/ACP transacylase. The fabG gene encoding 3- ketoacyl-ACP reductase and the acpP gene encoding acy] carrier protein are located just downstream of the fabD gene. Northern and promoter activity analysis demonstrated that the rpmF-plsX-fabH-fabD-fabG-acpP genes comprise an operon suggesting a coordinate control of the synthesis of a ribosomal protein (L32), PlsX protein, and fatty acid biosynthetic enzymes. However, several features were identified that are likely to be important for differential expression of the individual genes. These include the presence of multiple promoters, an internal terminator (attenuator), differential degradation of transcripts, and differential efficiency of translation initiation. Portions of transcripts arising upstream of rpmF terminate at the attenuator located just downstream of the plsX initiation codon, and some of the transcripts continue into the plsX-jab genes. The fabH-fabD-fabG-acpP genes are also cotranscribed from a promoter located upstream of the fabH gene, within the pisX structural gene. There are additional cotranscripts responsible for the expression of the fabD-fabG-acpP genes. The acpP gene is encoded by several more transcripts. Transcription initiation sites upstream of rpmF were identified by primer extension analysis and the attenuator site was identified by S1 mapping analysis. N-terminal amino acid sequence analysis identified the translation initiation codons of orfY, plsX, fabH, fabD and fabG. Short intergenic distances (15 and 12 bp) found between fabH and fabD and between fabD and fabG implicate translational coupling as a mechanism for coordinate control of fabHDG expression. The p/sX50 mutation was identified as deletion of a single nucleotide from the 6th codon of plsX resulting in a frame shift nonsense mutation. / Ph. D.

Accurate finite volume solution algorithms for the two dimensional Navier Stokes equations and the three dimensional Euler equations for both structured and unstructured grid topologies are presented. Results for two dimensional quadrilateral and triangular elements and three dimensional tetrahedral elements will be provided. Fundamental to the solution algorithm is a technique for generating multidimensional polynomials which model the spatial variation of the flow variables. Cell averaged data is used to reconstruct pointwise distributions of the dependent variables. The reconstruction errors are evaluated on triangular meshes. The implementation of the algorithm is unique in that three reconstructions are performed for each cell face in the domain. Two of the reconstructions are used to evaluate the inviscid fluxes and correspond to the right and left interface states needed for the solution of a Riemann problem. The third reconstruction is used to evaluate the viscous fluxes. The gradient terms that appear in the viscous fluxes are formed by simply differentiating the polynomial. By selecting the appropriate cell control volumes, centered, upwind and upwind-biased stencils are possible. Numerical calculations in two dimensions include solutions to elliptic boundary value problems, Ringleb’s flow, an inviscid shock reflection, a flat plate boundary layer, and a shock induced separation over a flat plate. Three dimensional results include the ONERA M6 wing. All of the unstructured grids were generated using an advancing front mesh generation procedure. Modifications to the three dimensional grid generator were necessary to discretize the surface grids for bodies with high curvature. In addition, mesh refinement algorithms were implemented to improve the surface grid integrity. Examples studied include a Glasair fuselage, High Speed Civil Transport, and the ONERA M6 wing. The role of reconstruction as applied to adaptive remeshing is discussed and a new first order error estimator is presented. Numerical examples of the remeshing procedure include both smooth and discontinuous flows. / Ph. D.

This thesis is a study of classical and quantum gravity with Ashtekar variables. The Ashtekar constraints are shown to capture the essence of the constraints and constraint algebra of General Relativity in four dimensions. A classification scheme of the solution space of the Ashtekar constraints is proposed and the corresponding physics is investigated. The manifestly covariant equations of motion for the Ashtekar variables are derived. Explicit examples are discussed and new classical solutions of General Relativity are constructed by exploiting the properties of the Ashtekar variables. Non-perturbative canonical quantization of the theory is performed. The ordering of the quantum constraints as well as the formal closure of the quantum constraint algebra are explored. A detailed Becchi-Rouet-Stora-Tyutin (BRST) analysis of the theory is given. The results demonstrate explicitly that in quantum gravity, fluctuations in topology can occur and there are strong evidences of phases in the theory. There is a phase which is described by a topological quantum field theory (TQFT) of the Donaldson-Witten type and an Abelian antiinstanton phase wherein self-interactions of the gravitational fields produce symmetry breaking from SO(3) to U(1). The full theory is much richer and includes fluctuations which bring the system out of the various restricted sectors while preserving diffeomorphism invariance. Invariants of the quantum theory with are constructed through BRST descents. They provide a clear and systematic characterization of non-local observables in quantum gravity, and can yield further differential invariants of four-manifolds. / Ph. D.

The expanding field of executive development programs was investigated. The field was found to be active and influenced by a number of different academic disciplines. However, no overall structure exists for guiding the examination, comparison or discussion of executive development programs. This work provides a structure in the form of a "framework for inquiry." The framework is then used to describe and analyze seven focus programs. Included in this study are the programs of the Naval Aviation Administration, Federal Executive Institute, Harvard University, U.S. Army War College, Center for Creative Leadership, Bell South, and the World Bank. All programs are thoroughly described and analyzed, but not evaluated. Use of the framework facilitates a comparative review of the similarities and differences of programs. This study demonstrates how a number of factors of the framework can combine to give a program a distinct overall identity. It also shows how certain factors may be very important in contributing to the identity of one program, but not important in contributing to another. This underscores the value of using the framework for inquiry in its entirety when studying executive development programs. This work also demonstrates other uses of the framework, including selection of a program by a prospective participant and development of a program by a sponsoring organization. The dissertation concludes with a prescriptive call for "program coherence," in which executive development program managers consciously align all program factors toward establishing and maintaining overall program identity. This identity should be consistent with the individual and organizational development goals of the program. / Ph. D.

Means of achieving rapid, efficient separations of analytes are explored in detail, with particular emphasis on the use of chromatographic and electrophoretic theory as an aid in system design and optimization. The benefits of miniaturization of chromatographic systems are assessed. First, the utility of semi-micro Ion Chromatography is explored by the manufacture of 2mm ID analytical and suppressor columns and a micro-conductivity cell. The quality of the columns and detector cell are evaluated by the separation of a test mixture and the calculation of peak variance contribution of the detector cell. The use of readily available analytical scale instrumentation for semi-micro IC is demonstrated. Next, a further downsizing of the IC system is described, in which 530μm ID fused silica tubing is utilized for column manufacture. In this case, a suppressor column is not used and UV detection is employed in the analysis of nucleoside monophosphates. Again, column performance characteristics are measured and noted. Application of this system to the separation of a hydrolysed nucleic acid sample demonstrates the feasibility of the technique to the analysis of volume-limited samples in low concentration with notable sensitivity. The benefits of a miniaturized liquid chromatographic system under pressure-driven flow is studied and the improved permeability of micropacked capillary columns is exploited in the manufacture of several 25 to 30cm columns which achieve high efficiencies with relatively low pressure drops. Van Deemter plots illustrate the performance characteristics of the columns. Finally, electroosmotic flow is studied as the motive force for liquid chromatographic separations. This combination of two techniques, packed capillary liquid chromatography and capillary electrophoresis, results in a system which achieves good resolving power through maximization of selectivity and efficiency. / Ph. D.

Le présent mémoire cherche à saisir quels sont les liens qui unissent la liturgie à l'évangélisation dans la mission de l'Église. Dans un premier chapitre, il s'agit donc de saisir la liturgie et l'évangélisation comme constituantes interreliées dans l'unité de la mission, et la liturgie comme révélatrice de la sacramentalité de la mission. Dans un second chapitre, il est question du lien logique gui unit la liturgie à l'évangélisation. Un troisième chapitre est consacré à l'inhérence de l'évangélisation dans la liturgie. Les conditions pour une liturgie évangélisatrice sont étudiées dans une quatrième et dernière partie.

La présente thèse considère la psychopharmacologie d'un point de vue philosophique. L'auteur commence par donner une définition formelle de la discipline basée sur la façon dont les psychopharmacologues voient leur discipline. La psychopharmacologie est l'étude scientifique de l'effet (d'interaction) des drogues, tel que la science peut le connaître, sur le psychisme et le comportement de l'organisme. Suivent une description des sous-disciplines de la psychopharmacologie et un bref examen d'autres opinions sur la discipline. L'auteur étudie ensuite le but de la psychopharmacologie. Celle-ci est une science appliquée, comme la médecine expérimentale dont elle est une sous-spécialité, par le biais de la psychiatrie, et elle vise à donner, par l'étude scientifique des effets de drogues, une meilleure compréhension des fondements neurophysiologiques du psychisme et du comportement, normal et anormal, de l'homme, afin de mener, plus ou moins directement, à une plus grande efficacité thérapeutique, notamment en ce qui a trait aux maladies mentales et à la toxicomanie. L'auteur soutient aussi que le but de la discipline doit être pratique plutôt que purement spéculatif. Troisièmement, l'auteur évalue la discipline par rapport à son but. Puisque le psychopharmacologue n'étudie que les fondements neurophysiologiques du psychisme et qu'il tend à considérer le comportement en négligeant ses assises psychiques et à s'appuyer de façon importante sur la recherche animale, il envisage l'homme en tant que connaissable au moyen des sciences de la nature et méconnaît ainsi son psychisme, ce qui a des répercussions importantes en thérapeutique. En outre, les attitudes associées à la recherche en psychopharmacologie et, plus généralement, en psychologie contribuent à accentuer ce peu d'importance accordé au psychisme. Bref, une orientation thérapeutique strictement psychopharmacologique permet peut-être de « guérir » des molécules et des comportements désordonnés, mais elle ne réussit pas à rejoindre le psychisme de l'homme, surtout au niveau spécifique de la raison, et il faut donc la tenir pour une dimension utile — voire nécessaire, bien qu'en elle-même insuffisante — dans le cadre d'une orientation thérapeutique plus vaste. Enfin, l'auteur attribue à une façon de penser erronée en psychologie la tendance à voir la nature humaine à la lumière de connaissances d'ordre strictement psychopharmacologique et il insiste sur l'importance d'un contexte plus réaliste dans lequel intégrer les résultats de la recherche en psychopharmacologie.

Considérer la danse comme un art et un langage, semble un fait acquis. Pourtant, les bases sur lesqueles repose une telle allégation doivent être examinées. Partant de l'analyse du discours théorique des intervenantes en danse éducative du 20e siècle, nous constatons que ces dernières, en attribuant des fonctions de communication et d'expression à la danse, l'assimilent à l'art et au langage. L'examen de cette assimilation exige dans un premier temps de définir ce qu'est la danse en général, puis dans un deuxième temps de définir à la fois ce que sont l'art et le langage. C'est en comparant ses caractéristiques à celles de l'art et du langage qu'il est possible de déterminer dans quelle mesure la danse peut leur être assimilée.