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A deep-sea time-lapse camera and several temperature probes were deployed on the Gulf of Mexico continental shelf at a biological community associated with a gas hydrate outcropping to study topographic and hydrologic changes over time. The deployment site, Bush Hill (GC 185), is located at 27°47.5' N and 91°15.0' W at depths of ~540m. The digital camera recorded one still image every six hours for three months in 2001, every two hours for the month of June 2002 and every six hours for the month of July 2002. Temperature probes were in place at the site for the entire experimental period. The data recovered provide a record of processes that occur at gas hydrate mounds. Biological activity was documented by identifying the fauna observed in the time-lapse record and recording the number of individuals and species in each image. 1,381 individual organisms representing 16 species were observed. Sediment resuspension and redistribution were regular occurrences during the deployment periods. By digitally analyzing the luminosity of the water column above the mound and plotting the results over time, the turbidity at the site was quantified. A significant diurnal pattern can be seen in both luminosity and temperature records, indicating a possible tidal or inertial component to deep-sea currents in this area. Contrary to expectations, there was no major change in shape or size of the gas hydrate outcrop at this site on the time frame of this study. This indicates that this particular mound was more stable than suggested by laboratory studies and prior in situ observations. The stable topography of the gas hydrate mound combined with high bacterial activity and sediment turnover appears to focus benthic predatory activity in the mound area. The frequency and recurrence of sediment resuspension indicates that short-term change in the depth and distribution of surface sediments is a feature of the benthos at the site. Because the sediment interface is a critical environment for hydrocarbon oxidation and chemosynthesis, short-term variability and heterogeneity may be important characteristics of these settings.

Macrobenthos of the deep, northern Gulf of Mexico have been sampled with large box cores along multiple cross-depth transects extending from depths of 200 m out to 3700 m. Four major depth zones have been identified based on the faunal similarities (beta diversity) between geographic sites, with the two intermediate-depth zones being divided horizontally down the middle of the basin. The input of food resources appears to control the observed patterns. Each zone and sub-zone can be described by a characteristic animal density, biomass and biodiversity (alpha diversity). Highest densities and biomass occurred in two large submarine canyons, the Mississippi and De Soto Canyon, but the two habitats are markedly different. The alpha diversity displays an intermediate depth maximum. Species richness (gamma diversity) is highest on east mid-slope, due, we suggest, to habitat complexity, but alpha diversity is lowest at the canyon head due to extreme dominance by amphipods. Small mean individual size and low densities encountered are a reflection of the meager surface water primary production, albeit with exceptional isolated habitats in which detrital material is concentrated, such as canyons on the upper continental slope.

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

Thesis (Ph. D.)--Ohio State University, 2002. / Title from first page of PDF file. Document formatted into pages; contains xx, 143 p.; also contains graphics. Includes abstract and vita. Advisor: L. Stanley Durkin, Dept. of Physics. Includes bibliographical references (p. 137-143).

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2009.

Several recently built inverted-T bent caps in Texas have shown significant inclined cracking triggering concern about current design procedures for such structures. The repair of such structures is very costly and often requires lane closures. For these reasons TxDOT funded Project 0-6416 aimed at obtaining a better understanding of the structural behavior of inverted-T bent caps and developing new design criteria to minimize such cracking in the future. Several tasks of the aforementioned project are addressed in this dissertation with particular focus on developing design criteria for strength and serviceability of inverted-T bent caps. Literature review revealed a scarcity of experimental investigation of inverted-T specimens. As part of this dissertation, an inverted-T database was assembled with experimental results from the literature and the current project. An extensive experimental program was completed to accomplish the objectives of the project with thirty one full-scale tests conducted on inverted-T beams. Experimental parameters varied in the study were: ledge length, ledge depth, web reinforcement, number of point loads, web depth, and shear span-to-depth ratio. The dissertation focuses on the effects of ledge length, ledge depth, number of point loads, and developing design criteria for strength and serviceability of inverted-T beams. Most inverted-T bent caps in Texas are designed using the traditional empirical design procedures outlined in the TxDOT bridge design manual LRFD (2011 current version) that follows closely the AASHTO LRFD bridge design specifications (2012 current version). Given the observed cracking in inverted-T bent caps, the accuracy and conservatism of the traditional design methods were evaluated based on experimental results. The accuracy and conservatism of STM design provisions recently developed in a TxDOT study (TxDOT Project 0-5253, Strength and Serviceability Design of Reinforced Concrete Deep Beams) were also evaluated. / text

Abstract Slope to Basin-floor Evolution of Channels to Lobes, Jurassic Los Molles Formation, Neuquén Basin, Argentina Nataleigh Kristine Vann, MS Geo Sci The University of Texas at Austin, 2013 Supervisor: Ronald J. Steel and Cornel Olariu The relatively steep and short-headed Neuquén Basin margin provides an excellent laboratory for demonstrating down slope changes in sediment gravity flow bed thickness, grain size and facies, as well as channel to lobe transitions. Approximately 400m high clinoformal, shelf-slope-basin-floor deposits of Jurassic Los Molles Formation outcrops are evaluated for reservoir scale definition of facies and architectures in the La Jardinera field area, Neuquén Basin. Slope deposits represent the accretionary front of the prograding shelf margin that were fed by a coarse grained shelf (Lajas Formation). Mapping of a high-resolution satellite images draped on digital elevation model resolved a sub-meter stratigraphic framework. Thirty-three measured sections from outcrops exposed along a 5km transect characterize the evolution of sand body architectures from the shelf edge to the basin floor. The Neuquén Basin margin is typified by four main depositional environments that transition from shelf edge incisions filled with conglomerates, to confined channels in upper- to middle-slope reaches, to weakly confined channels on the lower slope to sheet-like lobes and distributary channel complexes that drape onto both the lower slope and basin floor. Along the slope to basin floor profile the depositional architecture changes by overall decrease in grain size, amalgamation of beds and degree of erosion. Confined slope channels are up to 25m deep, isolated within muddy slope deposits and have complex multistory fills marked by basal and internal erosive contacts lined with mud-clast and/or pebble conglomerates. Channel axes contain amalgamated, medium to coarse sandstones that thin and fine towards channel margins over 100m. Down dip, lower slope channels are up to 400m wide and less than 10m thick. A marked reduction in mud clasts and conglomeratic material at basal erosional surfaces in weakly confined channels represent a downslope decrease in flow energy. However, distinct meter scale erosion surfaces continue to be recognizable where thin ripple laminated sands are truncated on channel margins by amalgamated structureless sands. Erosional surfaces are absent in laterally extensive (>5km), sheet-like lobes of basin-floor fans that are generally finer grained than lower or upper slope channel fills. There are lenticular debrites and thin micro-conglomerates associated with basin-floor fans. / text

Zinc Oxide (ZnO)is a wide band gap semiconductor which has attracted great attention because of its wide applicability. In order to obtain semiconductor devices with stable and reproducible properties further study of deep level defects is essential. DLTS (Deep level Transient Spectroscopy) is a direct and straightforward techniqueto determine the energy level of the deep level defects. Other information such as activation energy and capture cross section of the defect can also be obtained through this method. In our study ZnO single crystal samples were implanted by oxygen with the energy of 150keV. After the pretreatment of hydrogen peroxide, Schottky contacts were fabricated with Au film deposited by thermal evaporation. Deep level defects were studied by deep level transient spectroscopy (DLTS). Single peak spectra were observed in the as-implanted sample and samples anneal at 350oC, 650oC and 750oC with the corresponding activation energy decreasing with the annealing temperature from ~0.29eV as found in theas-implanted sample. Three peaks were identified in the DLTS spectra of the 900oC sample, with the activation energies of 0.11eV, 0.16eV and 0.37eV respectively.After analysis in detail we found some peaks in the DLTS spectra were the combination of two other peaks, dominated in different temperature range. The thermal evolutions of the deep levels up to the temperature of 1200oC were also investigated. / published_or_final_version / Physics / Master / Master of Philosophy

Drilling is a standard process for producing holes in metal materials. With an increased hole depth the demands increase on both machine and tool. Deep hole drilling is a complex process which ischaracterized by a high metal removal rate and hole accuracy. A hole deeper than ten times the diameter can be considered a deep hole which requires a specialized drilling technique. During adeep hole drilling process, the forces generated on the deep hole drill give a rise to a resultant radial force. The resultant radial force pushes the drill in a radial direction during a drilling operation. The radial force direction is of crucial importance in regard of tool guidance, stability and hole size accuracy. This force affects tool performance, reduces tool life and has an impact on the bore surface. Due to the complex nature of deep hole drilling, Sandvik Coromant wishes to get a better understanding of how their current deep hole drilling tools are balanced. The purpose of this study is to conduct a survey of a number of drills of Sandvik Coromant deep hole drill assortment. The main aim of this study is to calculate and measure the resultant radial force generated during a deep hole drilling operation. The forces are calculated with the aid of a calculation program and test-runs on a number of drills. This report presents the calculated magnitude and direction of the resultant radial force duringentrance, full intersection and at the exit of the workpiece. In addition to the measured values of theresultant radial force during entry and full intersection. Four different drill geometries are evaluated which of two are competitor drills. A deep hole drill geometry is re-modified in aspect to drill stability based on the outcome of the measured and calculated results. The results acquired from the performed calculation and measurements of the resultant showed that the resultant radial force acts in an angular direction that was outside the range between the support pads. This true for three of the four evaluated drill geometries. There were minor differences between the measured and calculated forces which enforce the reliability of the used calculation program. The modified drill geometry of a deep hole drill gave an indication of which geometry variables have impact on the resultant radial force magnitude and angular direction. The data presented in this report can be a base for future development of a deep hole drill toolgeometry in regard to the resultant radial force. Variables affecting the calculated results and theresultant radial force are presented and discussed. The study is concluded with suggestions of futurework based on the acquired data.