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High-speed wind-tunnel tests of gun openings in the nose of the fuselage of a 1/4-scale model

Description: From Summary: "In connection with recent tests of a 1/4-scale model pursuit airplane in the NACA 8-foot high-speed tunnel, gun openings having low drag were developed for installation in the nose of the fuselage. The increase in the fuselage-drag coefficient for the final form of openings was 0.0132 at a Mach number of 0.69 and at an angle of attack of 0 degrees. The corresponding drag coefficient based on the wing area was about 0.0005. The critical speed of the airplane was not affected by the gun openings."
Date: July 1942
Creator: Fedziuk, Henry A.
Partner: UNT Libraries Government Documents Department

Our Best Shots

Description: This poster was created by an art student for the annual Voertman Award Competition and Exhibition. The juror for the competition was Linda Cathcart. Depicted are soldiers and their weapons are a pencil, paintbrush and a crayon.
Date: 1980
Partner: UNT College of Visual Arts + Design

Voertman Awards / Call for Entries

Description: This poster was created by an art student for the 1983 Voertman Award Competition and Exhibition. Depicted near the bottom of the poster is a palette and paintbrush displayed as though a fine dish of food. The stylized design is in blue and pink.
Date: 1983
Partner: UNT College of Visual Arts + Design

Voertman Awards

Description: This poster was created by an art student for the annual Voertman Award Competition and Exhibition held in 1982. The juror is listed as Ric Collier, the Director of the Corpus Christi Art Museum.
Date: 1982
Partner: UNT College of Visual Arts + Design

ESF GROUND SUPPORT - MATERIAL DEDICATION ANALYSIS FOR STRUCTURAL STEEL AND ACCESSORIES FROM A COMMERCIAL GRADE SOURCE

Description: The purpose of this analysis is to select the critical characteristics to be verified for steel sets and accessories and the verification methods to be implemented through a material dedication process for the procurement and use of commercial grade structural steel sets and accessories (which have a nuclear safety function) to be used in ground support (with the exception of alcove ground support and alcove opening framing, which are not addressed in this analysis) for the Exploratory Studies Facility (ESF) Topopah Spring (TS) Loop. The ESF TS Loop includes the North Ramp, Main Drift, and South Ramp underground openings.
Date: January 23, 1996
Creator: Stine, M.D.
Partner: UNT Libraries Government Documents Department

Determining the toughness of ceramics from Vickers indentationsusing the crack-opening displacements: An experimental study

Description: Recently, a method for evaluating the fracture toughness of ceramics has been proposed based on the computed crack-opening displacements of cracks emanating from Vickers hardness indentations. In order to verify this method, experiments were carried out to determine the toughness of a commercial silicon carbide ceramic, Hexaloy SA, by measuring the crack-opening profiles of such Vickers indentation cracks. While the obtained toughness value of Ko = 2.3 MPavm was within 10% of that measured using conventional fracture toughness testing, the computed crack-opening profiles corresponding to this toughness displayed poor agreement with those measured experimentally, raising concerns about the suitability of this method for determining the toughness of ceramics. The effects of subsurface cracking and cracking during loading are considered as possible causes of such discrepancies, with the former based on evidence observed for secondary radial cracking which affected the crack opening profile and deduced toughness values.
Date: October 30, 2002
Creator: Kruzic, J.J. & Ritchie, R.O.
Partner: UNT Libraries Government Documents Department

Drop Tests for the 6M Specification Package Closure Investigation

Description: Results of tests of drum-type RAM packages employing conventional clamp-ring closures have caused concern over the DOT 6M Specification Package. To clarify these issues, a series of tests were performed to determine the response of the clamp-ring closure to the regulatory Hypothetical Accident Condition (9m) drop tests, for packages at maximum allowable weight. Three enhanced closure designs were also tested: the Clamshell, plywood disk reinforcement, and J-Clip. The results of the tests showed that the standard closure was unable to retain the top for both Center-of-Gravity-Over-Corner and Shallow Angle cases, for the standard package, at its maximum allowed weight. Similar results were found for packages dropped from a reduced height. The Clamshell design provided the best performance of the enhanced closures. It was concluded that the closure ring design employed on the 6M is inadequate to retain the top during the regulatory test sequence, for packages at the maximum allowed weight. For large heavy packages, the Center-of-Gravity- Over-Corner case is more challenging than the Shallow Angle case. The Clamshell design securely retained the top for all HAC test cases, and prevented formation of any opening which could compromise fire test performance.
Date: April 30, 2004
Creator: SMITH, AC
Partner: UNT Libraries Government Documents Department

Contribution to the nsac long-range plan entitled

Description: This is a time of great opportunity in nuclear spectroscopy. The development of radioactive beam capabilities around the world is opening a new landscape for discovery, and the connections between nuclear structure studies and astrophysics, neutrino physics, and physics beyond the standard model are stronger than ever. New detector technologies are evolving which can meet the challenges of the new generation of experiments. Leading these is the technology of ''{gamma}-ray tracking'' which can revolutionize {gamma}-ray spectroscopy in a way that large arrays of {gamma} detectors did a decade ago. During the last few years this technology has been shown feasible and GRETINA a 1{pi} detector is under construction. However, the momentum in developing this technology to its full potential must continue towards GRETA, a full 4{pi} calorimeter. GRETA will carry {gamma}-ray spectroscopy into the next generation where it will be needed to fully exploit the science opportunities at radioactive beam facilities and increase the reach of stable beam facilities. In addition, {gamma}-ray tracking technology will have important applications for science, medicine, and homeland security.
Date: December 1, 2006
Creator: GRETINA Physics Working Group, the GRETINA Advisor
Partner: UNT Libraries Government Documents Department

Graphene Layer Growth: Collision of Migrating Five-MemberRings

Description: A reaction pathway is explored in which two cyclopenta groups combine on the zigzag edge of a graphene layer. The process is initiated by H addition to a five-membered ring, followed by opening of that ring and the formation of a six-membered ring adjacent to another five-membered ring. The elementary steps of the migration pathway are analyzed using density functional theory to examine the region of the potential energy surface associated with the pathway. The calculations are performed on a substrate modeled by the zigzag edge of tetracene. Based on the obtained energetics, the dynamics of the system are analyzed by solving the energy transfer master equations. The results indicate energetic and reaction-rate similarity between the cyclopenta combination and migration reactions. Also examined in the present study are desorption rates of migrating cyclopenta rings which are found to be comparable to cyclopenta ring migration.
Date: December 2, 2005
Creator: Whitesides, Russell; Kollias, Alexander C.; Domin, Dominik; Lester Jr., William A. & Frenklach, Michael
Partner: UNT Libraries Government Documents Department

Management of Leaks in Hydrogen Production, Delivery, and Storage Systems

Description: A systematic approach to manage hydrogen leakage from components is presented. Methods to evaluate the quantity of hydrogen leakage and permeation from a system are provided by calculation and testing sensitivities. The following technology components of a leak management program are described: (1) Methods to evaluate hydrogen gas loss through leaks; (2) Methods to calculate opening areas of crack like defects; (3) Permeation of hydrogen through metallic piping; (4) Code requirements for acceptable flammability limits; (5) Methods to detect flammable gas; (6) Requirements for adequate ventilation in the vicinity of the hydrogen system; (7) Methods to calculate dilution air requirements for flammable gas mixtures; and (8) Concepts for reduced leakage component selection and permeation barriers.
Date: April 27, 2006
Creator: Rawls, G
Partner: UNT Libraries Government Documents Department

Numerical experiments on the probability of seepage intounderground openings in heterogeneous fractured rock

Description: An important issue for the performance of underground nuclear waste repositories is the rate of seepage into the waste emplacement drifts. A prediction of this rate is particularly complicated for the potential repository site at Yucca Mountain, Nevada, because it is located in thick, unsaturated, fractured tuff formations. Underground opening in unsaturated media might act as capillary barriers, diverting water around them. In the present work, they study the potential rate of seepage into drifts as a function of the percolation flux at Yucca Mountain, based on a stochastic model of the fractured rock mass in the drift vicinity. A variety of flow scenarios are considered, assuming present-day and possible future climate conditions. They show that the heterogeneity in the flow domain is a key factor controlling seepage rates, since it causes channelized flow and local ponding in the unsaturated flow field.
Date: April 15, 1998
Creator: Birkholzer, J.; Li, G.; Tsang, C.F. & Tsang, Y.
Partner: UNT Libraries Government Documents Department

YAG:Dy and YAG:Tm Fluorescence Above 1400 C.

Description: Fluorescence from three samples of YAG:Tm, and three samples of YAG:Dy, with different activator concentrations, was measured for a wide temperature range, extending from room temperature to about 1700 C. Fluorescence lifetimes were measured for emissions at 460 nm from the YAG:Tm and at 453, 480, and 575 nm from YAG:Dy. The measurement system is described, including techniques for accommodating the high background blackbody radiation encountered at these very high temperatures. Data compilations are shown, including the fluorescence lifetimes over the temperature range of the measurement. This study has extended the high-temperature range of phosphor thermometry by approximately 200 C and shown the feasibility of using phosphor materials for very high temperature noncontact thermometry, opening up further applications for engines, materials, high-temperature processing, and related areas.
Date: August 1, 2003
Creator: Cates, M. R.
Partner: UNT Libraries Government Documents Department

Characterization of Fish Passage Conditions through a Francis Turbine, Spillway, and Regulating Outlet at Detroit Dam, Oregon, Using Sensor Fish, 2009

Description: Fish passage conditions through two spillways, a Francis turbine, and a regulating outlet (RO) at Detroit Dam on the North Santiam River in Oregon were evaluated by Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers (USACE), Portland District, using Sensor Fish devices. The objective of the study was to describe and compare passage exposure conditions, identifying potential fish injury regions within the routes. The study was performed in July, October, and December 2009 concurrent with HI-Z balloon-tag studies by Normandeau Associates, Inc. Sensor Fish data were analyzed to estimate 1) exposure conditions, particularly exposure to severe strike, collision, and shear events by passage route sub-regions; 2) differences in passage conditions between passage routes; and 3) relationships to live-fish injury and mortality data estimates. Comparison of the three passage routes evaluated at Detroit Dam indicates that the RO passage route through the 5-ft gate opening was relatively the safest route for fish passage under the operating conditions tested; turbine passage was the most deleterious. These observations were supported also by the survival and malady estimates obtained from live-fish testing. Injury rates were highest for turbine and spillway passage. However, none of the passage routes tested is safe for juvenile salmonid passage.
Date: May 6, 2011
Creator: Duncan, Joanne P. & Carlson, Thomas J.
Partner: UNT Libraries Government Documents Department

Evaluation of the Dallas Thompson Riverscreen Site on the Touchet River.

Description: Riverscreen irrigation pumps are a relatively new design in which the pump intake floats on the river surface, pulling water in only from the bottom side and surrounded by a self-cleaning screen. The Walla Walla County Conservation District recently started replacing old pump screens with the Riverscreen and was interested in whether the screens are protective of juvenile salmonids. Pacific Northwest National Laboratory evaluated approach velocities and operations at the Riverscreen installation on the Dallas Thompson property, approximately 3 mi. north of Touchet, Washington and 300 ft north of Hofer Dam, on June 18, 2007. Evaluation of this site consisted of underwater videography and water velocity measurements. The Dallas Thompson Riverscreen was pumping approximately 930 gpm during our evaluation, which is close to the maximum pumping rate for this model. Underwater videography showed only slow movement of water-borne particulates toward the pump intake, and the screen material was clean. All water velocity measurements were taken below the pump intake opening and between 3 to 6 in. from the screen face. All approach velocities (flow toward the screen and pump) were below National Marine Fisheries Service draft guidelines for juvenile fish screens.
Date: July 25, 2007
Creator: Chamness, Mickie
Partner: UNT Libraries Government Documents Department

Pair-Trawl Detection of PIT-Tagged Juvenile Salmonids Migrating in the Columbia River Estuary, 2008 Report of Research.

Description: In 2008, we sampled migrating juvenile Pacific salmonids Oncorhynchus spp. tagged with passive integrated transponder (PIT) tags using a surface pair trawl in the upper Columbia River estuary (rkm 61-83). The cod-end of the trawl was replaced with a cylindrical PIT-tag detection antenna with an 86-cm-diameter fish-passage opening and two detection coils connected in series. The pair trawl was 105 m long with a 91.5-m opening between the wings and a sample depth of 4.9 m. Also during 2008, we finalized the development of a prototype 'matrix' antenna, which was larger than previous antennas by a considerable magnitude. The matrix antenna consisted of 6 coils: a 3-coil front component and a 3-coil rear component, which were separated by 1.5-m of net mesh. The fish-passage opening was 2.5 m wide by 3.0 m tall and was attached to a standard-size pair trawl net. Intermittent sampling with a single crew began on 7 March and targeted yearling Chinook salmon O. tshawytscha and steelhead O. mykiss. Daily sampling using two crews began on 30 April and continued through 14 June; during this period we detected 2.7% of all juvenile salmonids previously detected at Bonneville Dam--a measure of sample efficiency. Sampling with a single crew continued through 20 August and targeted subyearling Chinook salmon. We detected 7,397 yearling Chinook salmon, 2,735 subyearling Chinook salmon, 291 coho salmon O. kisutch, 5,950 steelhead, and 122 sockeye salmon O. nerka in the upper estuary. We deployed the matrix antenna system and the older, cylindrical antenna system (86-cm-diameter fish-passage opening) simultaneously in mid-May 2008 to test matrix detection efficiency. The cylindrical antenna system had been used successfully in 2007 and early 2008. Because distribution of migrating salmonids in the estuary changes rapidly, we felt that a tandem sampling effort between the two systems was the only way to ...
Date: June 3, 2009
Creator: Magie, Robert J.; Morris, Matthew S. & Ledgerwood, Richard D.
Partner: UNT Libraries Government Documents Department

The Ring System of Uranus: Flat as a Pancake, Sprinkled with Dust

Description: We present a high quality image of the uranian ring system, obtained in July 2004 at 2.2 {micro}m with the adaptive optics camera NIRC2 on the Keck II telescope. Using these data, we report the first ground-based image of the ring 1986U2R, seen only once before by the Voyager spacecraft. We show that this ring extends inward to {approx} 7000 km above the Uranus cloud deck. Its VIF (total vertically integrated I/F) is {approx} 100 m. We further detected narrow sheets of dust in between the {delta} and {epsilon} rings, and in between rings 4 and {alpha}, with a VIF of 14 and 20 m, respectively. Surprisingly, we find that the particles in Uranus' 9 main rings are distributed within a mono-layer, rather than the usually adopted poly-layer model. We come to this conclusion via a comparison of the VIF as derived from our 2003 data at a ring opening angle B {approx} 18{sup o} (from Gibbard et al. 2004) with those derived in this paper at B {approx} 11{sup o}. We show that the VIF increases approximately as 1/sinB at the ring ansae, but is independent of sinB in front of the disk. This combination of factors can only be explained if the particles in Uranus' rings are distributed in a mono-layer, a configuration which makes the uranian system unique amongst the giant planets.
Date: February 2, 2005
Creator: de Pater, I; Gibbard, S G & Hammel, H B
Partner: UNT Libraries Government Documents Department

GLOVEBOX WINDOWS, FIRE PROTECTION AND VOICES FROM THE PAST

Description: 'Study the past--what is past is prologue'. These words appear as the motto on a pair of statues at the National Archives Building in Washington DC. They are also the opening sentence in the preface of a document written in August of 1956 entitled 'A Summary of Accidents and Incidents Involving Radiation in Atomic Energy Activities--June 1945 thru December 1955'. This document, one of several written by D.F. Hayes of the Safety and Fire Protection Branch, Division of Organization and Personnel, U.S. Atomic Energy Commission in Washington DC, and many others are often forgotten even though they contain valuable glovebox fire protection lessons for us today.
Date: April 15, 2009
Creator: Till, W
Partner: UNT Libraries Government Documents Department

Measuring the stress-bridging law of a heterogeneous material

Description: In this investigation, fracture experiments on a high explosive material (PBX 9501) were conducted using the digital image correlation technique. From the experimental measurement, we are able to determine quantitatively the stress-bridging law (or decohesion law), which characterizes the relationship between the bridging stress and the opening displacement cross the bridging zone. The plastic bonded HMX (PBX) high explosives are composed of the energetic crystal (HMX) and a polymeric binder. Previous experimental observations showed that the fracture process in the sugar mock, a simulant of the PBX 9501 high explosive, is very different from that in brittle solids, even though the high explosive material PBX 9501 is quite brittle under tension. A close examination of the fracture surface revealed that before crack initiation and propagation, a very large damage region is developed ahead of the crack tip. Since such a damage region is very narrow, it can be modeled as a stress bridging zone. Due to the presence of the sizable bridging zone, conventional fracture mechanics is no longer applicable. Stress bridging has to be considered explicitly in order to understand of fracture processes in the PBX 9501 high explosive and the sugar mock. The model, which explicitly incorporates stress-bridging mechanism, is shown in Fig.1. In describing the model, one would need the following quantities, bridging zone length R, bridging stress {sigma}(x{sub 1}), bridging-zone opening displacement {sigma}(x{sub 1}), and the critical stress, {sigma}{sub C}, at which bridging zone starts to develop. Among these quantities, the key element for the bridging model is the relationship between the bridging stress {sigma} and the opening displacement cross the bridging zone {sigma}, i.e., {sigma}({delta}), or the stress-bridging law that can only be determined through experimental measurement. In this study, fracture experiments on PBX 9501 high explosive using the digital image correlation technique were conducted. ...
Date: January 1, 2002
Creator: Liu, C. (Cheng)
Partner: UNT Libraries Government Documents Department

PID Tuning Using Extremum Seeking

Description: Although proportional-integral-derivative (PID) controllers are widely used in the process industry, their effectiveness is often limited due to poor tuning. Manual tuning of PID controllers, which requires optimization of three parameters, is a time-consuming task. To remedy this difficulty, much effort has been invested in developing systematic tuning methods. Many of these methods rely on knowledge of the plant model or require special experiments to identify a suitable plant model. Reviews of these methods are given in [1] and the survey paper [2]. However, in many situations a plant model is not known, and it is not desirable to open the process loop for system identification. Thus a method for tuning PID parameters within a closed-loop setting is advantageous. In relay feedback tuning [3]-[5], the feedback controller is temporarily replaced by a relay. Relay feedback causes most systems to oscillate, thus determining one point on the Nyquist diagram. Based on the location of this point, PID parameters can be chosen to give the closed-loop system a desired phase and gain margin. An alternative tuning method, which does not require either a modification of the system or a system model, is unfalsified control [6], [7]. This method uses input-output data to determine whether a set of PID parameters meets performance specifications. An adaptive algorithm is used to update the PID controller based on whether or not the controller falsifies a given criterion. The method requires a finite set of candidate PID controllers that must be initially specified [6]. Unfalsified control for an infinite set of PID controllers has been developed in [7]; this approach requires a carefully chosen input signal [8]. Yet another model-free PID tuning method that does not require opening of the loop is iterative feedback tuning (IFT). IFT iteratively optimizes the controller parameters with respect to a cost ...
Date: November 15, 2005
Creator: Killingsworth, N & Krstic, M
Partner: UNT Libraries Government Documents Department