In this thesis a constitutive model is developed for the numerical prediction of UD composite material behaviour under impact loading. Impact induced loading usually results in three dimensional stress states which significantly influences the failure behaviour. The heterogeneous nature of composite materials, in particular, results in a complex failure behaviour which manifests itself in various failure modes. Predicting the onset and evolution of these failure modes requires the use of physically based three dimensional theories for the prediction of the onset of damage and subsequent damage evolution. Furthermore, the use of polymeric matrices in continuous fibre reinforced composites results in a distinct directional strain rate dependent material behaviour which needs to be incorporated in constitutive models for the numerical simulation of impact events. The developed constitutive model relies on the prediction of the onset of damage evolution by the use of physically based three dimensional stress based failure criteria. A special feature of the proposed model is the identification of potential fracture planes. Numerically efficient algorithms for finding such planes are developed thus enabling the implementation into an explicit FE environment which was prohibitive so far. Damage evolution is simulated by degrading the tractions which are acting on the failure mode dependent fracture planes. The damage evolution and consequent energy dissipation is thereby driven by physically based dissipation potentials which consider only stresses which contribute to damage growth. The well known mesh dependent energy dissipation in Continuum Damage Mechanics is reduced by the introduction of an element size dependent parameter into the constitutive equations. An experimental program is conducted to investigate the compressive behaviour of composites. The focus of the study is on the rate dependent failure behaviour. The experiments are designed such that the failure mechanisms can be studied at varying strain rates with identical boundary conditions. This allows for direct conclusions about the strain rate dependent material behaviour. Novel optical measurement techniques are applied across all investigated strain rates thus ensuring an improved observation of the failure modes. The proposed constitutive model is finally verified by modelling of three point beam bending experiments which were performed quasi-statically and at impact velocities. The experimental technique for beam bending at impact loading was therefore improved thus yielding significantly more accurate experimental data.

The midtown aesthetic and culture, seen through the specific case of the group Musical Elements, reveals that the schism between uptown and downtown composers in New York in the 1970s is a critical construct that is an oversimplification of an infinitely more complex, dynamic and nuanced musical atmosphere. Furthermore, the hyper fixation on the uptown/downtown dichotomy as perpetuated by subsequent analysts has obscured the actual intersectional environment between uptown and downtown, in particular, the midtown aesthetic and culture, which is more accurately depicted as a transitional arena of cooperation and exchange operating successfully in between the perceptions of the polarized dichotomy. This thesis attempts to place Musical Elements as central to the development and promotion of a midtown culture, aesthetic, and sensibility. This is not to say that this ensemble represents the only ensemble or group of composers promoting a midtown culture. But a historiographical exploration of the so-called uptown/downtown schism, along with interviews with those affiliated with Musical Elements and analyses of works associated with the group, reveals how a midtown culture and philosophy helped bridge the gap between uptown and downtown.

The problem with which this paper is concerned is that of tracing Gothic elements in the six complete novels of Shirley Jackson (1919-1965). Jackson's novels, magazine reviews of these novels, articles on Gothicism, and histories of English literature form the sources of data for this research project.

The effect of excess gravity on bone-forming elements of the growing perichondrial shaft of embryonic chicks was investigated through the use of the transmission electron microscope and various cytochemical techniques.

The purpose of this thesis is to explore some of the characteristics of 0-simple semigroups and completely 0-simple semigroups.

The purpose of this thesis is to give a basic understanding of Percy Shelley's introduction to Gothicism and to explore the Gothic elements found within his writings.

The central subject of this thesis is the application of the concepts of symmetry and proportion in music and how these can be used to generate original compositions. Information about the musical application regarding concepts of symmetry and proportion both in the twentieth-century and earlier is provided. The first section also offers additional information about the construction of symmetrical harmony and its common usage; here too, principles of intervallic proportion are explained based on the compositional thinking of English composer Christopher Bochmann. The second section presents seven original compositions, each supported by their own commentary. Each work features a variety of instrumental forces ranging from solo to orchestral. Lending a separate emphasis (in analysis) to each composition helps to provide a broad picture of the potential that the ideas of symmetry and proportion bring to contemporary composition.

Spectrum splitting is an approach to increasing the conversion efficiency of a photovoltaic (PV) system. Several methods can be used to perform this function which requires efficient spatial separation of different spectral bands of the incident solar radiation. In this paper several of holographic methods for implementing spectrum splitting are reviewed along with the benefits and disadvantages associated with each approach. The review indicates that a volume holographic lens has many advantages for spectrum splitting in terms of both power conversion efficiency and energy yield. A specific design for a volume holographic spectrum splitting lens is discussed for use with high bandgap InGaP and low bandgap silicon PV cells. The holographic lenses are modeled using rigorous coupled wave analysis, and the optical efficiency is evaluated using non-sequential raytracing. A proof-of-concept off-axis holographic lens is also recorded in dichromated gelatin film and the spectral diffraction efficiency of the hologram is measured with multiple laser sources across the diffracted spectral band. The experimental volume holographic lens (VHL) characteristics are compared to an ideal spectrum splitting filter in terms of power conversion efficiency and energy yield in environments with high direct normal incidence (DNI) illumination and high levels of diffuse illumination. The results show that the experimental VHL can achieve 62.5% of the ideal filter power conversion efficiency, 64.8% of the ideal filter DNI environment energy yield, and 57.7% of the ideal diffuse environment energy yield performance.

Doctor of Philosophy / Division of Biology / Mark C. Ungerer / Nuclear genome size varies immensely across flowering plants, spanning nearly 2400-fold. The causes and consequences of this vast amount of variation have intrigued biologists since it became clear that nuclear DNA amount did not reflect organismal complexity (the so-called C-value paradox). In my dissertation I utilize wild sunflower species in the genus Helianthus to examine the role of transposable elements (TEs), and in particular, long terminal repeat (LTR) retrotransposons, in generating genome size variation and whether variation in genome size influences aspects of plant growth and development across multiple organizational levels. The genus Helianthus provides an excellent system for studying these questions given four-fold variation in nuclear DNA content among diploid species and well-resolved phylogenetic relationships. Utilizing short-read Illumina data and sequence information from a diverse panel of Helianthus annuus (common sunflower) full-length LTR retrotransposons, I found that nuclear genome size in Helianthus species is positively correlated with repetitive DNA, and LTR retrotransposon subtypes generally show similar patterns in genomic abundance across taxa. Helianthus species with the largest genomes, however, exhibit large-scale amplification of a small number of LTR retrotransposon subtypes. Measuring aspects of plant growth and development at cell-, organ- and whole plant-levels in a panel of diploid Helianthus species that vary 4-fold in nuclear genome size, I found that genome size is negatively correlated with cell production rate, but that this negative correlation does not persist at higher organizational levels. Taken together, these results provide insights into the mechanisms contributing to genome size evolution in plants and the organizational level at which genome size may impact growth patterns and developmental rates. Genome expansion in wild sunflowers is influenced most significantly by amplification of a small number of TEs and not necessarily by a greater diversity of TEs. Genome size is strongly negatively correlated with cell production rate but this relationship weakens at higher organizational levels, such as that of organ and whole-plant development.

Call number: LD2668 .T4 1957 R46 / Master of Science