Analysis of Kelvin-Helmholtz Instabilities Developing from Oblique Shock Interaction with a Heavy Gas Column

This thesis presents an experimental study of instabilities developing from oblique shock wave interaction with a heavy gas column. For these experiments, the gas column consists of pure sulfur hexafluoride infused with ~11% acetone gas by mass. A misalignment of the pressure and density gradients (from the shock wave) results in three-dimensional vorticity deposition on the gaseous interface. This is the main mechanism responsible for the formation of traditional Richtmyer-Meshkov instabilities (RMI). Other instabilities develop along the interface due to shear between the injected material and the post-shock air (moving at piston velocity behind the column). These instabilities present on the leading (with respect to the shock) and trailing edges of the column. On the leading edge, small perturbations are amplified by shear at the interface. This leads to the development of full billows, or ``cat\u27s eye\u27\u27 vortices, physically indistinguishable from Kelvin-Helmholtz instabilities (KHI). Certain characteristics of the KHI, such as initial instability growth rate and wavelength (lambda), depend on several factors including the Mach number of the shock wave, the shock tube angle of inclination (theta), and the post-shock compressed size of the column

Systematics and Floral Evolution in the Plant Genus Garcinia (Clusiaceae)

The pantropical genus Garcinia (Clusiaceae), a group comprised of more than 250 species of dioecious, trees and shrubs, is a common component of lowland tropical forests and is best known by the highly prized fruit of mangosteen (G. mangostana). The genus exhibits as extreme diversity of floral form as is found anywhere in angiosperms and there are many unresolved taxonomic issues surrounding the genus. To understand patterns of floral evolution within the group and to evaluate morphology-based classification schemes involving Garcinia and its relatives, relationships among a broad sample of Garcinia and close relatives were inferred by conducting Bayesian, parsimony, and likelihood analyses of sequence data from two nuclear genes, granule-bound starch synthase (GBSSI) and the internal transcribed spacer (ITS). The phylogenies suggest that all species of Garcinia fall into two major lineages one of which is characterized by the occurrence of nectariferous floral structures of uncertain derivation such as antesepalous appendages and intrastaminal disks and rings and the other by their absence. Several additional clades are supported each sharing particular combinations of floral characters and that generally correspond to sections recognized in the most recent taxonomic treatment of the genus. These results support a broad circumscription of Garcinia to include the segregate genera Ochrocarpos, Pentaphalangium, Rheedia, and Tripetalum. The monophyly of tribe Garcinieae is supported. The nectariferous floral appendages, disks and rings that characterize one of the major lineages identified in the molecular phylogenetic analyses have been hypothesized to represent an outer whorl of stamens. The position of these structures in mature Garcinia flowers does not support this interpretation. To better understand the nature of these structures in Garcinia, floral development and anatomy were studied in a sample of six Garcinia species. An outer whorl, staminodal origin for the disks and appendages is not supported by developmental timing or position. Disks and appendages are not apparent until late in development and the disks arise in the center of flower. Anatomical data are equivocal. These data also reject a gynoecial origin for these structures, and suggest that they are instead intrastaminal receptacular nectaries that are independent of the floral organs

Characterization of single- and multi-phase shock-accelerated flows

Experiments conducted in the Shock Tube Facility at the University of New Mexico are focused on characterization of shock-accelerated flows. Single-phase (gaseous) initial conditions consist of a heavy gas column of sulfur hexafluoride seeded with approximately 11% acetone gas by mass. Visualization of the image plane for gaseous initial conditions is accomplished via planar laser-induced fluorescence (PLIF) with a high-powered Nd:YAG ultraviolet laser and an Apogee Alta U-42 monochrome CCD camera, with a quantum efficiency \u3e 90%. Multi-phase (gas-solid) initial conditions consist of glass micro-beads deposited on small 1-cm diameter discs of specific surface chemistry, mounted flush with the bottom wall of the test section. Visualization of the resulting multi-phase instabilities is achieved via Mie-scattering of visible light (532nm wavelength) laser pulses and a Hadland Imacon 200, with an effective frame rate of 200 X 106 frames per second. Fundamental properties of disparate gas mixtures of sulfur hexafluoride and helium, subjected to shock wave acceleration, are also studied, with implications that kinetic molecular theory can account for discrepancies between theory and experiment

Monitoring and analysing attendance in first year university mathematics tutorials

As part of an innovative tutorial structure introduced to a first year university mathematics subject, an attendance monitoring system was implemented. The system collected data that was used to investigate the relationship between student attendance and assessment performance which is reported here. The implementation of this system also assisted in the increase of student participation and engagement

Test Fill to Determinate the Compression Behavior of a Closed Industrial Waste Landfill 10.07

A test fill was constructed over a closed, industrial waste landfill located in southeastern Michigan. The objective of this test fill was to evaluate the immediate and time-dependent response of the existing landfill to an increase in load. The closed landfill contains a widely varying mixture of non-hazardous industrial wastes such as foundry sand, ash, and wastewater treatment sludge. It also contains construction and demolition debris. The surface of the landfill is relatively flat and, at the site of the test fill, is underlain by approximately 30 feet (9.1 m) of waste, some 15 feet (4.6 m) of which is saturated. Native clay till underlies the closed landfill and is approximately 8 feet (2.4 m) thick. A fractured, relatively non-weathered limestone underlies the till. The test fill was comprised of approximately 5000 cubic yards (3,800 m3) of clay and was 12 feet (3.7 m) thick at its peak. The size at the base was approximately 160 feet (48.8 m) by 140 feet (42.7 m). The settlement of the existing landfill surface beneath the test fill was monitored with three laterally-distributed settlement points. Settlement of up to 0.5 feet (0.15 m) occurred concurrent with imposition of the increased load. On completion of the test fill construction, the settlement pattern became linear with the logarithm of time. From this data, load-dependent and time-dependent compression characteristics were estimated for the in-place industrial waste

Methods and apparatus for the on-site production of hydrogen peroxide

Methods, apparatus, and applications for the on-site production of hydrogen peroxide are described. An embodiment of the apparatus comprises at least one anolyte chamber coupled to at least one anode, at least one catholyte chamber, wherein the at least one catholyte chamber is coupled to at least one cathode, at least one anode membrane and at least one cathode membrane, wherein the anode membrane is adjacent to the at least one anode, wherein the cathode membrane is adjacent to the at least one cathode, at least one central chamber disposed between the at least one anolyte chamber and the at least one catholyte chamber. Hydrogen peroxide is produced by reduction of an oxygen-containing gas at the cathode

Detection of large exact subgraph isomorphisms with a topology-only graphlet index built using deterministic walks

We introduce the first algorithm to perform topology-only local graph matching (a.k.a. local network alignment or subgraph isomorphism): BLANT, for Basic Local Alignment of Network Topology. BLANT first creates a limited, high-specificity index of a single graph containing connected k-node induced subgraphs called k-graphlets, for k=6-15. The index is constructed in a deterministic way such that, if significant common network topology exists between two networks, their indexes are likely to overlap. This is the key insight which allows BLANT to discover alignments using only topological information. To align two networks, BLANT queries their respective indexes to form large, high quality local alignments. BLANT is able to discover highly topologically similar alignments (S3 >= 0.95) of up to 150 node-pairs for which up to 50% of node pairs differ from their "assigned" global counterpart. These results compare favorably against the baseline, a state-of-the-art local alignment algorithm which was adapted to be topology-only. Such alignments are 3x larger and differ 30% more (additive) more from the global alignment than alignments of similar topological similarity (S3 >= 0.95) discovered by the baseline. We hope that such regions of high local similarity and low global similarity may provide complementary insights to global alignment algorithms.Comment: 13 pages, 11 figures, 4 table