72 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Transients"  
Results: 1 - 24 next
open access

Searching for optical transients in real-time : the RAPTOR experiment /.

Description: A rich, but relatively unexplored, region in optical astronomy is the study of transients with durations of less than a day. We describe a wide-field optical monitoring system, RAPTOR, which is designed to identify and make follow-up observations of optical transients in real-time. The system is composed of an array of telescopes that continuously monitor about 1500 square degrees of the sky for transients down to about 12' magnitude in 60 seconds and a central fovea telescope that can reach 16… more
Date: January 1, 2002
Creator: Vestrand, W. T. (W. Thomas); Borozdin, K. N. (Konstantin N.); Brumby, Steven P.; Casperson, D. E. ( Donald E.); Fenimore, Edward E.; Galassi, M. C. (Mark C.) et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Flow field design development using the segmented cell approach

Description: We report on fuel cell flow-field development employing two-dimensional computational fluid dynamics (2-D CFD). Simulation of the flow distribution of a parallel channel flow-field, with a simple one-channel manifold, predicted inhomogeneous performance distribution within the cell. Further modeling, focusing on modification of the inlet and outlet flow fields, was used to predict a more homogeneous flow distribution in the flow-field. Attempts were made to verify the theoretical predictions ex… more
Date: January 1, 2002
Creator: Bender, G. (Guido) & Ramsey, J. C. (John C.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Real-time detection of optical transients with RAPTOR

Description: Fast variability of optical objects is an interesting though poorly explored subject in modern astronomy. Real-time data processing and identification of transient, celestial events in the images is very important, for such study as it allows rapid follow-up with more sensitive instruments, We discuss an approach which we have chosen for the RAPTOR project which is a pioneering close-loop system combining real-time transient detection with rapid follow-up. Our data processing pipeline is able t… more
Date: January 1, 2002
Creator: Borozdin, K. N. (Konstantin N.); Brumby, Steven P.; Galassi, M. C. (Mark C.); McGowan, K. E. (Katherine E.); Starr, D. L. (Dan L.); Vestrand, W. T. (W. Thomas) et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Spatial distribution of the CO transient response of a PEFC

Description: We report on the investigation of the current distribution of a PEFC under the influence of CO impurities in the hydrogen feed stream by application of the segmented cell system. Stepping the CO partial pressure of the anode feed stream from 0 to 100 ppm CO the current response of the cell was recorded for different stoichiometric flows. A poisoning time delay occurs along the flow path due to the anode flow rate. Also anode and cathode processes, e.g. CO turnover and oxygen mass transport limi… more
Date: January 1, 2002
Creator: Bender, G. (Guido) & Zawodzinski, T. A. (Thomas A.), Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Transient PrOx carbon monoxide measurement, control, and optimization

Description: Fuel processing systems for low temperature polymer electrolyte membrane (PEM) fuel cell systems require control of the carbon monoxide concentration to less than 100 ppm to 10 ppm in the anode feed. Conventional hydrocarbon fuel processors use a water-gas shift (WGS) reactor to react CO with water to form H2 and reduce the CO concentration. The CO conversion is limited by equilibrium at the outlet temperature of the WGS reactor. The WGS outlet CO concentration can range from over 1% to 2000 pp… more
Date: January 1, 2002
Creator: Inbody, M. A. (Michael A.); Borup, R. L. (Rodney L.) & Tafoya, J. (Jose I.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Advances in recording scattered light changes in crustacean nerve with electrical activation

Description: We investigated optical changes associated with crustacean nerve stimulation using birefringent and large angle scattered light. Improved detection schemes disclosed high temporal structure of the optical signals and allowed further investigations of biophysical mechanisms responsible for such changes. Most studies of physiological activity in neuronal tissue use techniques that measure the electrical behavior or ionic permeability of the nerve, such as voltage or ion sensitive dyes injected in… more
Date: January 1, 2002
Creator: Carter, Kathleen M.; Rector, David M.; Martinez, Anne T.; Guerra, Francisco M. & George, John S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Detector for advanced neutron capture experiments at LANSCE

Description: The Detector for Advanced Neutron Capture Experiments (DANCE) is a 159-element 4x barium fluoride array designed to study neutron capture on small quantities, 1 mg or less, of radioactive nuclides. It is being built on a 20 m neutron flight path which views the 'upper tier' water moderator at the Manuel J. Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center. The detector design is based on Monte Carlo calculations which have suggested ways to minimize backgrounds due to… more
Date: January 1, 2002
Creator: Ullmann, J. L. (John L.); Reifarth, R. (Rene); Haight, Robert C.; Hunt, L. F. (Lloyd F.); O'Donnell, J. M.; Bredeweg, T. A. (Todd A) et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Transient control of carbon monoxide with staged PrOx reactors

Description: Fuel Processor systems generate hydrogen for fuel cell systems from hydrocarbon fuels such as gasoline for automotive fuel cell systems and natural gas for stationary fuel cell systems. These fuel processor systems must remove any contaminants to levels that won't poison the fuel cell before the outlet hydrogen-rich gas stream can be used by the fuel cell to generate electricity. Carbon monoxide is a contaminant that must be removed to levels of < 100 ppm or < 10 ppm depending on the CO t… more
Date: January 1, 2002
Creator: Inbody, M. A. (Michael A.); Borup, R. L. (Rodney L.) & Tafoya, J. (Jose I.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Transient thermohydraulic heat pipe modeling : incorporating THROHPUT into the Caesar environment /

Description: The THROHPUT code, which models transient thermohydraulic heat pipe behavior, is being incorporated into the CAESAR computational physics development environment. The CAESAR environment provides many beneficial features for enhanced model development, including levelized design, unit testing, Design by ContractTM (Meyer, 1997), and literate programming (Knuth, 1992), in a parallel, object-based manner. The original THROHPUT code was developed as a doctoral thesis research code; the current emph… more
Date: January 1, 2002
Creator: Hall, Michael L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

From shock response spectrum to temporal moments and vice-versa

Description: Temporal momerils have been used in engineering mechanics to condense the information contained in the shock response spectrum into a few scalar quantities. This paper presents an application of temporal moments to the propagation of an explosive-driven shock wave through an assembly of metallic parts. For this particular application, it is shown that temporal moments characterize the response of the system better than other features traditionally used in the analysis of nonlinear, transient ev… more
Date: January 1, 2002
Creator: Hemez, F. M. (François M.) & Doebling, S. W. (Scott W.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Information-gap robustness for the test analysis correlation of nonlinear transient simulation

Description: An alternative to the theory of probability is applied to the problem of assessing the robustness of test-analysis correlation to parametric sources of uncertainty. The analysis technique is based on the theory of information-gap, which models the clustering of uncertain events in families of nested sets instead of assuming a probability structure. The system investigated is the propagation of a transient impact through a layer of hyper-elastic material. The two sources of non-linearity are the… more
Date: January 1, 2002
Creator: Hemez, F. M. (François M.); Ben-Haim, Yakov, & Cogan, S. (Scott)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Computational modeling and analysis of a flow in a storage room

Description: When a radioactive material gas is accidentally released with a room, the present of the hazardous gas will directly affect the people safety inside. In this study, the flow field and gas dispersion in a ventilated tritium storage room at Los Alamos National Laboratory was simulated using CFX-5.5, a commercially available CFD package using a finite volume methodology. CFD models provide a simultaneously numerical solution of continuity, Navier-Stokes, and energy equations for a flow field geome… more
Date: January 1, 2002
Creator: Chen, Z. (Zukun); Konecni, S. (Snezana) & Whicker, J. J. (Jeffrey J.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

Description: A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed… more
Date: August 1, 2002
Creator: O'Brien, James Edward; Sohal, Manohar Singh & Huff, George Albert
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Low-Temperature, Vacuum-Aided Thermal Desorption Studies on a Simulated Organic Sludge Waste

Description: This report describes an initial set of small scale lab tests conducted on surrogate waste materials to investigate mass release behavior of volatile organics (VOC’s) from a solidified liquid organic sludge matrix under vacuumaided, low-temperature thermal desorption conditions. Low temperature thermal desorption is being considered as a potential processing technology alternative to incineration, to remove gas generation limitations affecting the transportation of transuranic (TRU) contaminate… more
Date: December 1, 2002
Creator: Farnsworth, R. K.; Peterman, D. R.; Anderson, Gary L. & Garn, T. G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Verification of the W76-1 hostile environments model

Description: Demonstrating mesh convergence for a finite element analysis requires multiple meshes, but creating high quality meshes is a time-consuming task. Furthermore, estimates of the amount of error caused by mesh refinement are difficult to make for a sequence of unrelated, unstructured finite element meshes. A solution for both of these problems is to automatically generate a refined mesh by subdividing every element in the original mesh. The resulting refined mesh has a uniform 'mesh refinement rat… more
Date: January 1, 2002
Creator: Stevens, R. Robert
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Flow Characteristics of Pulse Cleaning System in Ceramic Filter

Description: The rigid ceramic filters have been recognized to be a most promising kind of equipment for the gas-solid separation and the cleaning of hot gases due to their unique properties and higher separation efficiency for larger than 5 {micro}m particles, which will well meet downstream system component protection and environmental standards. They have potential for increased efficiency in advanced coal-fired power generation systems like pressurized fluidized bed combustion (PFBC) and integrated gasi… more
Date: September 19, 2002
Creator: Zhongli, J.; Peng, S.; Chen, H. & Shi, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Analysis of the Lattice-Boltzmann-Based Code PowerFLOW: Flow Through a Parallel Confined Jet

Description: Recent advances in the development and practical implementation of the Lattice-Boltzmann (LB) method as applied to computational fluid dynamics (CFD) have spurred much interest. A simple literature search of this area yielded well over 200 articles published in the open literature since 1997. The key advantage of the LB method is the time-accurate simulation of complex flow phenomena that are intractable with traditional methods. Analysis of flow in a parallel confined jet (PCJ) has been perfor… more
Date: August 23, 2002
Creator: III, S.J. Vinay & J.R. Buchanan, Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures

Description: Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially design… more
Date: April 1, 2002
Creator: Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

RELAP5/MOD3.2 analysis of INSC standard problem INSCSP - R7 : void fraction distribution over RBMK fuel channel height for experiments performed in the ENTEK BM test facility.

Description: The RELAP5/MOD3.2 computer program has been used to analyze a series of tests investigating void fraction distribution over height in RBMK fuel channels performed in Facility BM at the ENTEK. This is RBMK Standard Problem 7 in Joint Project 6, which is the investigation of Computer Code Validation for Transient Analysis of RBMK and VVER Reactors, between the United States and Russian Minatom International Nuclear Safety Centers. The experiment facility and data, RELAP5 nodalization, and results… more
Date: May 24, 2002
Creator: Garner, P. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Mechanisms and Determinants of RNA Turnover: Plant IRESs and Polycistrons for Metabolic Engineering

Description: There is a strong need for tools that allow multiple transgenes to be expressed in genetically engineered plants. For the last 30 years it has been believed that nearly all eukaryotic mRNAs were monocistronic, with ribosomes entering at the 5' end and scanning through the 5'UTR to the first AUG codon. It is now clear that perhaps 3% of vertebrate and yeast mRNAs utilize IRESs (Internal Ribosome Entry Sites) within their 5'UTRs to promote the internal entry of ribosomes to mRNAs and subsequent t… more
Date: August 1, 2002
Creator: Meagher, Richard B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Chemical-Specific Representation of Air-Soil Exchange and Soil Penetration in Regional Multimedia Models

Description: In multimedia mass-balance models, the soil compartment is an important sink as well as a conduit for transfers to vegetation and shallow groundwater. Here a novel approach for constructing soil transport algorithms for multimedia fate models is developed and evaluated. The resulting algorithms account for diffusion in gas and liquid components; advection in gas, liquid, or solid phases; and multiple transformation processes. They also provide an explicit quantification of the characteristic so… more
Date: August 1, 2002
Creator: McKone, T.E. & Bennett, D.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Demonstration in the DIII-D Tokamak of an Alternate Baseline Scenario for ITER and Other Burning Plasma Experiments

Description: OAK A271 DEMONSTRATION IN THE DIII-D TOKAMAK OF AN ALTERNATE BASELINE SCENARIO FOR ITER AND OTHER BURNING PLASMA EXPERIMENTS. Discharges which can satisfy the high gain goals of burning plasma experiments have been demonstrated in the DIII-D tokamak in stationary conditions with relatively low plasma current (q{sub 95} > 4). A figure of merit for fusion gain {Beta}{sub N}H{sub 89}/q{sub 95}{sup 2} has been maintained at values corresponding to Q = 10 operation in a burning plasma for > 6 … more
Date: November 1, 2002
Creator: Luce, T. C.; Wade, M. R.; Ferron, J. R.; Hyatt, A. W.; Kellman, A. G.; Kinsey, J. E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

RELAP5 / MOD3.2 analysis of INSC standard problem INSCSP - R7 : void fraction distribution over RBMK fuel channel height for experiments performed in the ENTEK BM test facility.

Description: The RELAP5/MOD3.2 computer program has been used to analyze a series of tests investigating void fraction distribution over height in RBMK fuel channels performed in Facility BM at the ENTEK. This is RBMK Standard Problem 7 in Joint Project 6, which is the investigation of Computer Code Validation for Transient Analysis of RBMK and VVER Reactors, between the United States and Russian Minatom International Nuclear Safety Centers. The experiment facility and data, RELAP5 nodalization, and results… more
Date: August 22, 2002
Creator: Garner, P. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

GDH pipe break transient analysis of the RBMK - 1500.

Description: Presented in this paper is the transient analysis of a Group Distribution Header (GDH) following a guillotine break at the end of the header. The GDH is the most important component of reactor safety in case of accidents. Emergency Core Cooling System (ECCS) piping is connected to the GDH piping such that, during an accident, coolant passes from the GDH into the ECCS. The GDH that is propelled into motion after a guillotine break can impact neighboring GDH pipes or the nearest wall of the compa… more
Date: May 15, 2002
Creator: Kulak , R.; Marcherta, A. & Dundulis, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen