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Advance Abrasion Resistant Materials for Mining

Description: The high-density infrared (HDI) transient-liquid coating (TLC) process was successfully developed and demonstrated excellent, enhanced (5 times higher than the current material and process) wear performance for the selected functionally graded material (FGM) coatings under laboratory simulated, in-service conditions. The mating steel component exhibited a wear rate improvement of approximately one and a half (1.5) times. After 8000 cycles of. wear testing, the full-scale component testing demonstrated that the coating integrity was still excellent. Little or no spalling was observed to occur.
Date: June 1, 2004
Creator: Mackiewicz-Ludtka, G.
Partner: UNT Libraries Government Documents Department

ADVANCED ABRASION RESISTANT MATERIALS FOR MINING

Description: The high-density infrared (HDI) transient-liquid coating (TLC) process was successfully developed and demonstrated excellent, enhanced (5 times higher than the current material and process) wear performance for the selected functionally graded material (FGM) coatings under laboratory simulated, in-service conditions. The mating steel component exhibited a wear rate improvement of approximately one and a half (1.5) times. After 8000 cycles of wear testing, the full-scale component testing demonstrated that the coating integrity was still excellent. Little or no spalling was observed to occur.
Date: April 8, 2004
Creator: Ludtka, G. M.
Partner: UNT Libraries Government Documents Department

The pathogen transmission avoidance theory of sexual selection

Description: The current theory that sexual selection results from female preference for males with good genes suffers from several problems. An alternative explanation, the pathogen transmission avoidance hypothesis, argues that the primary function of showy traits is to provide a reliable signal of current disease status, so that sick individuals can be avoided during mating. This study shows that a significant risk of pathogen transmission occurs during mating and that showy traits are reliable indicators of current disease status. The origin of female choosiness is argued to lie in a general tendency to avoid sick individuals, even in the absence of showy traits, which originate as exaggerations of normal traits that are indicative of good health (bright feathers, vigorous movement, large size). Thus, in this new model the origins of both showy traits and female choosiness are not problematic and there is no threshold effect. This model predicts that when the possession of male showy traits does not help to reduce disease in the female, showy traits are unlikely to occur. This case corresponds to thorough exposure of every animal to all group pathogens, on average, in large groups. Such species are shown with a large data set on birds to be less likely to exhibit showy traits. The good-genes model does not make this prediction. The pathogen transmission avoidance model can also lead to the evolution of showy traits even when selection is not effective against a given pathogen (e.g., when there is no heritable variation for resistance), but can result in selection for resistance if such genes are present. Monogamy is argued to reduce selection pressures for showy traits; data show monogamous species to be both less parasitized and less showy. In the context of reduction of pathogen transmission rates in showy populations, selection pressure becomes inversely frequency-dependent, which ...
Date: August 1, 1997
Creator: Loehle, C.
Partner: UNT Libraries Government Documents Department

Sexual selection as a consequence of pathogen avoidance behaviors

Description: The current theory that sexual selection results from female choice for good genes suffers from several problems. An alternative explanation is proposed. The pathogen avoidance hypothesis argues that the primary function of showy traits is to provide a reliable signal of current disease status so that sick individuals may be avoided during mating. Our studies shown that a significant risk of pathogen transmission occurs during mating and that showy traits are reliable indicators of current disease status. The origin of female choosiness is argued to lie in a general tendency to avoid sick individuals, even in the absence of showy traits. The showy traits are argued to originate as simple exaggerations of normal traits that are indicative of good health (bright feathers; vigorous movement; large size). Thus the origins of both showy traits and female choosiness are not problematic in this theory. A game theory analysis is employed to formalize the theory. Results of the game theory model support the theory. In particular, when the possession of male showy traits does not help reduce disease in the female, then showy traits are unlikely to occur. This case corresponds to the situation in large flocks or herds in which every animal is thoroughly exposed to all group pathogens on average. Such species do not exhibit showy traits. The good genes model does not make this prediction. The pathogen avoidance model can also lead to the evolution of showy traits even when selection is not effective against a given pathogen (e.g., when there is no heritable variation for resistance) but will lead to selection for resistance if such genes are present. Overall, the pathogen avoidance hypothesis provides a complete alternative to the good genes theory.
Date: August 1, 1997
Creator: Loehle, C. & Logofet, D.O.
Partner: UNT Libraries Government Documents Department

Equipment design guidelines for remote hot cell operations.

Description: Hot cells provide a unique and challenging environment for designing remotely operated equipment. A typical hot cell is an isolated room used to protect operators from highly contaminated and radioactive equipment. Hot cells usually have thick reinforced concrete walk and leaded glass windows. Operations within the hot cell are accomplished using master-slave manipulators and overhead crane or electro-mechanical manipulator systems. The inability to perform hands-on operation and maintenance in hot cells requires special design considerations. Some of these design considerations include operational interfaces, radiation, accessibility, replaceability/interchangeability, decontamination, atmospheric conditions, functionality, operator fatigue, and ease of use. This paper will discuss guidelines for designing hot cell remotely operated equipment that has been used successfully at Argonne National Laboratory. General topics in this paper will include master-slave manipulator types and limitations, overhead handling systems, viewing limitations, types and sizes of typical fasteners, hot cell compatible materials, mockup testing, guide features for mating parts, modularity, labeling, electrical fasteners, and lifting fixtures.
Date: July 10, 1998
Creator: Wahlquist, D. R.
Partner: UNT Libraries Government Documents Department

Probing the Elastic-Plastic, Time-Dependant Response of Test Fasteners using Finite Element Analysis (FEA)

Description: The evolution of global and local stress/strain conditions in test fasteners under test conditions is investigated using elastic-plastic, time-dependent finite element analyses (FEA). For elastic-plastic response, tensile data from multiple specimens, material heats and test temperatures are integrated into a single, normalized flow curve from which temperature dependency is extracted. A primary creep model is calibrated with specimen- and fastener-based thermal relaxation data generated under a range of times, temperatures, stress levels and environments. These material inputs are used in analytical simulations of experimental test conditions for several types of fasteners. These fastener models are constructed with automated routines and contact conditions prescribed at all potentially mating surfaces. Thermal or mechanical room temperature pre-loading, as appropriate for a given fastener, is followed by a temperature ramp and a dwell time at constant temperature. While the amount of thermal stress relaxation is limited for the conditions modeled, local stress states are highly dependent upon geometry (thread root radius, for example), pre-loading history and thermal expansion differences between the test fastener and test fixture. Benefits of this FE approach over an elastic methodology for stress calculation will be illustrated with correlations of Stress Corrosion Cracking (SCC) initiation time and crack orientations in stress concentrations.
Date: December 13, 2004
Creator: Renauld, ML & Lien, H
Partner: UNT Libraries Government Documents Department

Processing of alumina-niobium interfaces via liquid-film-assistedjoining

Description: Alumina-niobium interfaces were fabricated at 1400 C via solid-state diffusion brazing of a 127-{micro}m-thick niobium foil between alumina blocks. Prior to brazing, some of the alumina mating surfaces, both polished and unpolished, were evaporation-coated with copper films {approx}1.4 {micro}m, {approx}3.0 {micro}m, and {approx}5.5 {micro}m thick to induce liquid-film-assisted joining at the brazing temperature. The effects of copper film thickness and surface roughness on fracture characteristics and ceramic-metal interfacial microstructure were investigated by room-temperature four-point bend tests, optical microscopy, profilometry, and atomic force microscopy. The average strength of bonds between niobium and polished alumina substrates increased with the introduction of copper film interlayers, and the scatter in strength tended to decrease, with an optimum combination of strength and Weibull modulus arising for a copper film thickness of 3.0 {micro}m. The strength characteristics of niobium bonded to unpolished alumina substrates were also improved by liquid-film-assisted joining, but were unaffected by the thickness of the copper interlayers.
Date: February 15, 2005
Creator: McKeown, Joseph T.; Sugar, Joshua D.; Gronsky, Ronald & Glaeser,Andreas M.
Partner: UNT Libraries Government Documents Department

RADIOACTIVE MATERIAL SHIPPING PACKAGINGS AND METAL TO METAL SEALS FOUND IN THE CLOSURES OF CONTAINMENT VESSELS INCORPORATING CONE SEAL CLOSURES

Description: The containment vessels for the Model 9975 radioactive material shipping packaging employ a cone-seal closure. The possibility of a metal-to-metal seal forming between the mating conical surfaces, independent of the elastomer seals, has been raised. It was postulated that such an occurrence would compromise the containment vessel hydrostatic and leakage tests. The possibility of formation of such a seal has been investigated by testing and by structural and statistical analyses. The results of the testing and the statistical analysis demonstrate and procedural changes ensure that hydrostatic proof and annual leakage testing can be accomplished to the appropriate standards.
Date: June 6, 2007
Creator: Loftin, B; Glenn Abramczyk, G & Allen Smith, A
Partner: UNT Libraries Government Documents Department

Predicting dissolution patterns in variable aperture fractures: 1. Development and evaluation of an enhanced depth-averaged computational model

Description: Water-rock interactions within variable-aperture fractures can lead to dissolution of fracture surfaces and local alteration of fracture apertures, potentially transforming the transport properties of the fracture over time. Because fractures often provide dominant pathways for subsurface flow and transport, developing models that effectively quantify the role of dissolution on changing transport properties over a range of scales is critical to understanding potential impacts of natural and anthropogenic processes. Dissolution of fracture surfaces is controlled by surface-reaction kinetics and transport of reactants and products to and from the fracture surfaces. We present development and evaluation of a depth-averaged model of fracture flow and reactive transport that explicitly calculates local dissolution-induced alterations in fracture apertures. The model incorporates an effective mass transfer relationship that implicitly represents the transition from reaction-limited dissolution to transport-limited dissolution. We evaluate the model through direct comparison to previously reported physical experiments in transparent analog fractures fabricated by mating an inert, transparent rough surface with a smooth single crystal of potassium dihydrogen phosphate (KDP), which allowed direct measurement of fracture aperture during dissolution experiments using well-established light transmission techniques [Detwiler, et al., 2003]. Comparison of experiments and simulations at different flow rates demonstrate the relative impact of the dimensionless Peclet and Damkohler numbers on fracture dissolution and the ability of the computational model to simulate dissolution. Despite some discrepancies in the small-scale details of dissolution patterns, the simulations predict the evolution of large-scale features quite well for the different experimental conditions. This suggests that our depth-averaged approach to simulating fracture dissolution provides a useful approach for extending laboratory results that are often limited in scale to scales that are more representative of geologic processes of interest.
Date: April 21, 2006
Creator: Detwiler, R L & Rajaram, H
Partner: UNT Libraries Government Documents Department

Development of the Butt Joint for the ITER Central Solenoid

Description: The ITER Central Solenoid (CS) requires compact and reliable joints for its Cable-in-Conduit Conductor (CICC). The baseline design is a diffusion bonded butt joint. In such a joint the mating cables are compacted to a very low void fraction in a copper sleeve and then heat treated. After the heat treatment the ends are cut, polished and aligned against each other and then diffusion bonded under high compression in a vacuum chamber at 750 C. The jacket is then welded on the conductor to complete the joint, which remarkably does not require more room than a regular conductor. This joint design is based on a proven concept developed for the ITER CS Model Coil that was successfully tested in the previous R&D phase.
Date: August 23, 2006
Creator: Martovetsky, N. N.
Partner: UNT Libraries Government Documents Department

Using an immune system model to explore mate selection in genetic algorithms.

Description: In the setting of multimodal function optimization, engineering and machine learning, identifying multiple peaks and maintaining subpopulations of the search space are two central themes when Genetic Algorithms (GAs) are employed. In this paper, an immune system model is adopted to develop a framework for exploring the role of mate selection in GAs with respect to these two issues. The experimental results reported in the paper will shed more light into how mate selection schemes compare to traditional selection schemes. In particular, we show that dissimilar mating is beneficial in identifying multiple peaks, yet harmful in maintaining subpopulations of the search space.
Date: January 1, 2003
Creator: Huang, C. F. (Chien-Feng)
Partner: UNT Libraries Government Documents Department

The multi-niche crowding genetic algorithm: Analysis and applications

Description: The ability of organisms to evolve and adapt to the environment has provided mother nature with a rich and diverse set of species. Only organisms well adapted to their environment can survive from one generation to the next, transferring on the traits, that made them successful, to their offspring. Competition for resources and the ever changing environment drives some species to extinction and at the same time others evolve to maintain the delicate balance in nature. In this disertation we present the multi-niche crowding genetic algorithm, a computational metaphor to the survival of species in ecological niches in the face of competition. The multi-niche crowding genetic algorithm maintains stable subpopulations of solutions in multiple niches in multimodal landscapes. The algorithm introduces the concept of crowding selection to promote mating among members with qirnilar traits while allowing many members of the population to participate in mating. The algorithm uses worst among most similar replacement policy to promote competition among members with similar traits while allowing competition among members of different niches as well. We present empirical and theoretical results for the success of the multiniche crowding genetic algorithm for multimodal function optimization. The properties of the algorithm using different parameters are examined. We test the performance of the algorithm on problems of DNA Mapping, Aquifer Management, and the File Design Problem. Applications that combine the use of heuristics and special operators to solve problems in the areas of combinatorial optimization, grouping, and multi-objective optimization. We conclude by presenting the advantages and disadvantages of the algorithm and describing avenues for future investigation to answer other questions raised by this study.
Date: September 1, 1995
Creator: Cedeno, W.
Partner: UNT Libraries Government Documents Department

[News Clip: Gorilla]

Description: Video footage from the KXAS-TV/NBC station in Fort Worth, Texas, to accompany a news story.
Date: May 20, 1980, 10:00 p.m.
Creator: KXAS-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

Formation of mushrooms and lignocellulose degradation encoded in the genome sequence of Schizophyllum commune

Description: The wood degrading fungus Schizophyllum commune is a model system for mushroom development. Here, we describe the 38.5 Mb assembled genome of this basidiomycete and application of whole genome expression analysis to study the 13,210 predicted genes. Comparative analyses of the S. commune genome revealed unique wood degrading machinery and mating type loci with the highest number of reported genes. Gene expression analyses revealed that one third of the 471 identified transcription factor genes were differentially expressed during sexual development. Two of these transcription factor genes were deleted. Inactivation of fst4 resulted in the inability to form mushrooms, whereas inactivation of fst3 resulted in more but smaller mushrooms than wild-type. These data illustrate that mechanisms underlying mushroom formation can be dissected using S. commune as a model. This will impact commercial production of mushrooms and the industrial use of these fruiting bodies to produce enzymes and pharmaceuticals.
Date: July 12, 2010
Creator: Ohm, Robin A.; de Jong, Jan F.; Lugones, Luis G.; Aerts, Andrea; Kothe, Erika; Stajich, Jason E. et al.
Partner: UNT Libraries Government Documents Department

ULTRACOATINGS: Enabling Energy and Power Solutions in High Contact Stress Environments through Next-Generation Nanocoatings

Description: This industry-driven project was the result of a successful response by Eaton Corporation to a DOE/ITP Program, Grand Challenge, industry call. It consisted of a one-year effort in which ORNL participated in the area of friction and wear testing. In addition to Eaton Corporation and ORNL (CRADA), the project team included: Ames Laboratory, who developed the underlying concept for titanium- zirconium-boron (TZB) based nanocomposite coatings; Borg-Warner Morse TEC, an automotive engine timing chain manufacturer in Ithaca, New York, with its own proprietary hard coating; and Pratt & Whitney Rocketdyne, Inc., a dry-solids pump manufacturer in San Fernando Valley, California. This report focuses only on the portion of work that was conducted by ORNL, in a CRADA with Eaton Corporation. A comprehensive final report for the entire effort, which ended in September 2010, has been prepared for DOE by the team. The term 'ultracoatings' derives from the ambitious technical target for the new generation of nanocoatings. As applications, Eaton was specifically considering a fuel pump and a gear application in which the product of the contact pressure and slip velocity during operation of mating surfaces, commonly called the 'PV value', was equal to or greater than 70,000 MPa-m/s. This ambitious target challenges the developers of coatings to produce material capable of strong bonding to the substrate, as well as high wear resistance and the ability to maintain sliding friction at low, energy-saving levels. The partners in this effort were responsible for the selection and preparation of such candidate ultracoatings, and ORNL used established tribology testing capabilities to help screen these candidates for performance. This final report summarizes ORNL's portion of the nanocomposite coatings development effort and presents both generated data and the analyses that were used in the course of this effort. Initial contact stress and speed calculations showed that laboratory ...
Date: September 30, 2011
Creator: Blau, P.; Qu, J. & Higdon, C. III (Eaton Corp.)
Partner: UNT Libraries Government Documents Department

Methyl-parathion decreases sperm function and fertilization capacity after targeting spermatocytes and maturing spermatozoa

Description: Paternal germline exposure to organophosphorous pesticides (OP) has been associated with reproductive failures and adverse effects in the offspring. Methyl parathion (Me-Pa), a worldwide-used OP, has reproductive adverse effects and is genotoxic to sperm. Oxidative damage has been involved in the genotoxic and reproductive effects of OP. The purpose of this study was to determine the effects of Me-Pa on spermatozoa function and ability to fertilize. Male mice were exposed to Me-Pa (20 mg/kg bw, i.p.) and spermatozoa from epididymis-vas deferens were collected at 7 or 28 days post-treatment (dpt) to assess the effects on maturing spermatozoa and spermatocytes, respectively. DNA damage was evaluated by nick translation (NT-positive cells) and SCSA (percentDFI); lipoperoxidation (LPO) by malondialdehyde production; sperm function by spontaneous- and induced-acrosome reactions (AR); mitochondrial membrane potential (MMP) by using the JC-1 flurochrome; and, fertilization ability by an in vitro assay and in vivo mating. Results showed alterations in DNA integrity (percentDFI and NT-positive cells) at 7 and 28 dpt, in addition to decreased sperm quality and a decrease in induced-AR; reduced MMP and LPO was observed only at 7 dpt. We found negative correlations between LPO and all sperm alterations. Altered sperm functional parameters were associated with reduced fertilization rates at both times, evaluated either in vitro or in vivo. These results show that Me-Pa exposure of maturing spermatozoa and spermatocytes affects many sperm functional parameters that result in a decreased fertilizing capacity. Oxidative stress seems to be a likely mechanism ofthe detrimental effects of Me-Pa in male germ cells.
Date: May 3, 2009
Creator: Pina-Guzman, Belem; Sanchez-Gutierrez, M.; Marchetti, Francesco; Hernandez-Ochoa, I.; Solis-Heredia, M.J . & Quintanilla-Vega, B.
Partner: UNT Libraries Government Documents Department

Evaluation of HFIR LEU Fuel Using the COMSOL Multiphysics Platform

Description: A finite element computational approach to simulation of the High Flux Isotope Reactor (HFIR) Core Thermal-Fluid behavior is developed. These models were developed to facilitate design of a low enriched core for the HFIR, which will have different axial and radial flux profiles from the current HEU core and thus will require fuel and poison load optimization. This report outlines a stepwise implementation of this modeling approach using the commercial finite element code, COMSOL, with initial assessment of fuel, poison and clad conduction modeling capability, followed by assessment of mating of the fuel conduction models to a one dimensional fluid model typical of legacy simulation techniques for the HFIR core. The model is then extended to fully couple 2-dimensional conduction in the fuel to a 2-dimensional thermo-fluid model of the coolant for a HFIR core cooling sub-channel with additional assessment of simulation outcomes. Finally, 3-dimensional simulations of a fuel plate and cooling channel are presented.
Date: March 1, 2009
Creator: Primm, Trent; Ruggles, Arthur & Freels, James D
Partner: UNT Libraries Government Documents Department

NCSX Trim Coil Design

Description: The National Compact Stellarator Experiment (NCSX) was being constructed at the Princeton Plasma Physics Laboratory in partnership with Oak Ridge National Laboratory before work was stopped in 2008. The objective of this experiment was to develop the stellarator concept and evaluate it's potential as a model for future fusion power plants. Stellarator design requires very precisely positioned Modular Coils of complex shape to form 3D plasmas. In the design of NCSX, Trim Coils were required to compensate for both the positioning of the coils during assembly and the fabrication tolerances of the Modular Coils. Use of the Trim Coils allowed for larger tolerances increasing ease of assembly and decreasing overall cost. A set of Trim coils was developed to suppress the toroidal flux in island regions due to misalignment, magnetic materials, and eddy currents. The requirement imposed upon the design forced the toroidal flux in island regions below 10% of the total toroidal flux in the plasma. An analysis was first performed to evaluate candidate Trim Coil configurations iterating both the size, number, and position of the coils. The design was optimized considering both performance and cost while staying within the tight restraints presented by the space limited geometry. The final design of the Trim Coils incorporated a 48 Coil top bottom symmetric set. Fabrication costs were minimized by having only two coil types and using a planar conventional design with off the shelf commercial conductor. The Trim Coil design incorporated supports made from simple structural shapes assembled together in a way which allowed for adjustment as well as accommodation for the tolerance build up on the mating surfaces. This paper will summarize the analysis that led to the optimization of the Trim Coils set, the trim coil mechanical design, thermal and stress analysis, and the design of the supporting ...
Date: May 29, 2009
Creator: M. Kalish, A. Brooks, J. Rushinski, R. Upcavage
Partner: UNT Libraries Government Documents Department

Developing Multiple Diverse Potential Designs for Heat Transfer Utilizing Graph Based Evolutionary Algorithms

Description: This paper examines the use of graph based evolutionary algorithms (GBEAs) to find multiple acceptable solutions for heat transfer in engineering systems during the optimization process. GBEAs are a type of evolutionary algorithm (EA) in which a topology, or geography, is imposed on an evolving population of solutions. The rates at which solutions can spread within the population are controlled by the choice of topology. As in nature geography can be used to develop and sustain diversity within the solution population. Altering the choice of graph can create a more or less diverse population of potential solutions. The choice of graph can also affect the convergence rate for the EA and the number of mating events required for convergence. The engineering system examined in this paper is a biomass fueled cookstove used in developing nations for household cooking. In this cookstove wood is combusted in a small combustion chamber and the resulting hot gases are utilized to heat the stove’s cooking surface. The spatial temperature profile of the cooking surface is determined by a series of baffles that direct the flow of hot gases. The optimization goal is to find baffle configurations that provide an even temperature distribution on the cooking surface. Often in engineering, the goal of optimization is not to find the single optimum solution but rather to identify a number of good solutions that can be used as a starting point for detailed engineering design. Because of this a key aspect of evolutionary optimization is the diversity of the solutions found. The key conclusion in this paper is that GBEA’s can be used to create multiple good solutions needed to support engineering design.
Date: September 1, 2006
Creator: Jr., David J. Muth
Partner: UNT Libraries Government Documents Department