Stochastic Engine Convergence Diagnostics (open access)

Stochastic Engine Convergence Diagnostics

The stochastic engine uses a Markov Chain Monte Carlo (MCMC) sampling device to allow an analyst to construct a reasonable estimate of the state of nature that is consistent with observed data and modeling assumptions. The key engine output is a sample from the posterior distribution, which is the conditional probability distribution of the state of nature, given the data. In applications the state of nature may refer to a complicated, multi-attributed feature like the lithology map of a volume of earth, or to a particular related parameter of interest, say the centroid of the largest contiguous sub-region of specified lithology type. The posterior distribution, which we will call f, can be thought of as the best stochastic description of the state of nature that incorporates all pertinent physical and theoretical models as well as observed data. Characterization of the posterior distribution is the primary goal in the Bayesian statistical paradigm. In applications of the stochastic engine, however, analytical calculation of the posterior distribution is precluded, and only a sample drawn from the distribution is feasible. The engine's MCMC technique, which employs the Metropolis-Hastings algorithm, provides a sample in the form of a sequence (chain) of possible states of nature, …
Date: December 11, 2001
Creator: Glaser, R
Object Type: Report
System: The UNT Digital Library
Review of Excess Weapons Plutonium Disposition LLNL Contract Work in Russia-(English) (open access)

Review of Excess Weapons Plutonium Disposition LLNL Contract Work in Russia-(English)

This third meeting of the recently completed and ongoing Russian plutonium immobilization contract work was held at the State Education Center (SEC) in St. Petersburg on January 14-18, 2002. The meeting agenda is reprinted here as Appendix A and the attendance list as Appendix B. The meeting had 58 Russian participants from 21 Russian organizations, including the industrial sites (Mayak, Krasonayarsk-26, Tomsk), scientific institutes (VNIINM, KRI, VNIPIPT, RIAR), design organizations (VNIPIET and GSPI), universities (Nyzhny Novgorod, Urals Technical), Russian Academy of Sciences (Institute of Physical Chemistry or IPhCh, Institute of Ore-Deposit Geology, Petrography, Mineralogy, and Geochemistry or IGEM), Radon-Moscow, S&TC Podol'osk, Kharkov-Ukraine, GAN-SEC-NRS and SNIIChM, the RF Ministry of Atomic Energy (Minatom) and Gosatomnadzor (GAN). This volume, published by LLNL, documents this third annual meeting. Forty-nine technical papers were presented by the Russian participants, and nearly all of these have been collected in this Proceedings. The two objectives for the meeting were to: (1) Bring together the Russian organizations, experts, and managers performing this contract work into one place for four days to review and discuss their work amongst each other. (2) Publish a meeting summary and proceedings of all the excellent Russian plutonium immobilization and other plutonium disposition contract …
Date: July 11, 2002
Creator: Jardine, L & Borisov, G B
Object Type: Report
System: The UNT Digital Library
Hydroacoustic Blockage Calibration for Discrimination (open access)

Hydroacoustic Blockage Calibration for Discrimination

The core focus of this hydroacoustic research is to develop a better understanding of hydroacoustic blockage to better predict those stations that can be used in discrimination analysis for any particular event. The research involves two approaches: (1) model-based assessment of blockage and (2) ground-truth data-based assessment of blockage. The goal is to reliably determine all hydroacoustic stations that can be brought to bear on a discrimination analysis from any event location in the world s oceans. An important aspect of this capability is to include reflected T-phases where they reliably occur since reflected T-phases can allow station utilization when the direct path is otherwise completely blocked. We have conceptually designed an approach to automate assessment procedures that will allow both model-based and data-based methodologies to be utilized and in the future, integrated. We have modified the HydroCAM model-based network assessment code to include variable density bathymetry grids. This will improve the reliability of model-based blockage assessment as dense bathymetry grids are added to the bathymetry database where available and needed. We are also running the HydroCAM code to produce blockage grids in the Indian Ocean for many different blockage criteria. We have been building the database necessary to begin …
Date: July 11, 2003
Creator: Harben, Philip E.; Matzel, Eric; Upton, Zachary & Pulli, Jay J.
Object Type: Article
System: The UNT Digital Library
Cross Sections for (Gamma)-Ray Production in the 191ir (N,Xn(Gamma)) Reactions (open access)

Cross Sections for (Gamma)-Ray Production in the 191ir (N,Xn(Gamma)) Reactions

Discrete {gamma}-ray spectra have been measured for nuclei populated in {sup 191}Ir(n{sub 4}xn{gamma}) with x{<=}11, as a function of incident neutron energy using neutrons from the 'white' neutron source at the Los Alamos Neutron Science Center's WNR facility. The energy of the neutrons was determined using the time-of-flight technique. The data were taken using the GEANIE spectrometer. The cross sections for emission of 202 {gamma} rays of {sup 181-191}Ir were determined for neutron energies 0.2 MeV < E{sub n} < 300 MeV. Comparison with model calculations, using the GNASH reaction model, and with GEANIE results from the similar {sup 193}Ir(n{sub 4}xn{gamma}) reactions is made.
Date: January 11, 2005
Creator: Fotiades, N.; Nelson, R. O.; Devlin, M.; Chadwick, M. B.; Talou, P.; Becker, J. A. et al.
Object Type: Article
System: The UNT Digital Library
Tests of the Contamination Analysis Unit, Phase 2 (open access)

Tests of the Contamination Analysis Unit, Phase 2

Lawrence Livermore National Laboratory (LLNL) has developed a mass spectrometer-based system that measures organic surface residues in situ. This system, called the Contamination Analysis Unit (CAU), can detect and quantify a variety of volatile surface residues on a range of different substrates. Residue samples are removed from the substrate using a combination of vacuum and thermal desorption, and are then ionized and quantified by a quadrupole mass spectrometer. The current effort (Phase 2) was carried out in accordance with Thiokol Project Test Plan PTP-0467. A first phase of tests was completed under PTP-0327 and the results reported in TWR-75385. The Phase 2 test plan, PTP-0467, is a follow-on to PTP-0327, and was conducted in order to more fully determine the capabilities of the CAU. This report summarizes experiments in which the CAU was evaluated for application in reusable solid rocket motor production scenarios. The report has been ordered by the tasks requested by ATK Thiokol Propulsion Testplan PTP-0467. Project tasks included the following: (1) Determine the amount of residual propellant and liner components with the CAU after coupons have been cleaned. (2) Determine if the CAU can detect solvent that has soaked into NBR. (3) Test the capabilities of the …
Date: September 11, 2003
Creator: Meltzer, Michael & Daley, Paul
Object Type: Report
System: The UNT Digital Library
CRYOGENIC SYSTEM FOR BEPCII SRF CAVITY, IR QUADRUPOLE AND DETECTOR SOLENOID MAGNETS. (open access)

CRYOGENIC SYSTEM FOR BEPCII SRF CAVITY, IR QUADRUPOLE AND DETECTOR SOLENOID MAGNETS.

Beijing Electron-Positron Collider Upgrade (BEPCII) requires three types of superconducting facilities, including one pair of SRF cavities, one pair of interaction region quadrupole magnets, and one detector solenoid magnet. The cryo-plant for BEPCII has a total cooling capacity of 1kW at 4.5K, which is composed of two separate helium refrigerators of 500W each. Two refrigerators share the same gas storage and recovery system. The engineering design for the cryogenic systems, including power leads, control dewars, subcooler, cryogenic valve boxes, cryogenic transfer-lines and cryogenic controls, is completed. The production of its subsystem is under way. This paper summarizes the progress in cryogenics of the BEPCII project.
Date: May 11, 2004
Creator: JIA,J. X. & L., WANG.
Object Type: Article
System: The UNT Digital Library
FEMIS Installation Guide v1.5.3 SR1 Addendum to the FEMIS System Administration Guide v1.5.3 (open access)

FEMIS Installation Guide v1.5.3 SR1 Addendum to the FEMIS System Administration Guide v1.5.3

FEMIS v1.5.3 SR1 includes updates to Section 2.0, FEMIS UNIX Installation, for the FEMIS Installation Guide.
Date: February 11, 2004
Creator: Homer, Brian J.; Carter, Richard J.; Dunkle, Julie R.; Johnson, Sharon M. & Wood, Blanche M.
Object Type: Text
System: The UNT Digital Library
Proteomic Characterization of Host Response to Yersinia pestis (open access)

Proteomic Characterization of Host Response to Yersinia pestis

Host-pathogen interactions result in protein expression changes within both the host and the pathogen. Here, results from proteomic characterization of host response following exposure to Yersinia pestis, the causative agent of plague, and to two near neighbors, Y. pseudotuberculosis and Y. enterocolitica, are reported. Human monocyte-like cells were chosen as a model for macrophage immune response to pathogen exposure. Two-dimensional electrophoresis followed by mass spectrometry was used to identify host proteins with differential expression following exposure to these three closely related Yersinia species. This comparative proteomic characterization of host response clearly shows that host protein expression patterns are distinct for the different pathogen exposures, and contributes to further understanding of Y. pestis virulence and host defense mechanisms. This work also lays the foundation for future studies aimed at defining biomarkers for presymptomatic detection of plague.
Date: May 11, 2004
Creator: Chromy, B.; Perkins, J.; Heidbrink, J.; Gonzales, A.; Murhpy, G.; Fitch, J. P. et al.
Object Type: Article
System: The UNT Digital Library
A Multi-Layered Image Cache for Scientific Visualization (open access)

A Multi-Layered Image Cache for Scientific Visualization

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Date: April 11, 2003
Creator: LaMar, E C & Pascucci, V
Object Type: Article
System: The UNT Digital Library
Simulation Analysis of Inspections of International Travelers at Los Angeles International Airport for US-VISIT (open access)

Simulation Analysis of Inspections of International Travelers at Los Angeles International Airport for US-VISIT

The United States Visitor and Immigrant Status Indicator Technology Program (US-VISIT) will deploy biometric and other systems to identify and track foreign nationals entering and exiting the U.S. Evaluation of the large number of possible policy options and technical configurations for implementation of US-VISIT requires validated system analyses with appropriate tools that can address the requirements of this new program and its processes. Early identification of performance issues and capability gaps will prove critical to the success of the program.
Date: February 11, 2004
Creator: Edmunds, T.; Sholl, P.; Yao, Y.; Gansemer, J.; Cantwell, E.; Prosnitz, D. et al.
Object Type: Report
System: The UNT Digital Library
Simulations of Turbulence Induced Ellipticity Over Large Fields-of-View: The First Step Towards Enabling LSST Weak Lensing Science (open access)

Simulations of Turbulence Induced Ellipticity Over Large Fields-of-View: The First Step Towards Enabling LSST Weak Lensing Science

Atmospheric turbulence can mimic the effects of weak lensing in astronomical images, so it is necessary to understand to what degree turbulence affects weak lensing measurements. In particular, we studied the ellipticity induced upon the point-spread functions (PSFs) of a grid of simulated stars separated by distances (d {approx} 1{prime}) that will be characteristic of Large Synoptic Survey Telescope (LSST) images. We observe that atmospherically induced ellipticity changes on small scales (d < 0.5{prime}) and use linear interpolation between stars separated by d = 0.5{prime} to determine the induced ellipticity everywhere in the field-of-view.
Date: October 11, 2004
Creator: Schlaufman, K
Object Type: Report
System: The UNT Digital Library
Aggregation quenching in thin films of meh-ppv studied by near-field scanning optical microscopy and spectroscopy (open access)

Aggregation quenching in thin films of meh-ppv studied by near-field scanning optical microscopy and spectroscopy

Aggregates in thin films of conjugated polymers form excimer states and significantly reduce the photo- and electroluminescence efficiency in devices produced from these materials. We have studied the aggregate formation in thin films of MEH-PPV by near-field scanning optical microscopy and spectroscopy. Local photoluminescence spectroscopy and photo-bleaching experiments have been used to show that thin films of MEH-PPV are homogeneously aggregated and do not form aggregated domains.
Date: April 11, 2000
Creator: Huser, T & Yan, M
Object Type: Article
System: The UNT Digital Library
Progress in accident analysis of the HYLIFE-II inertial fusion energy power plant design (open access)

Progress in accident analysis of the HYLIFE-II inertial fusion energy power plant design

The present work continues our effort to perform an integrated safety analysis for the HYLIFE-II inertial fusion energy (IFE) power plant design. Recently we developed a base case for a severe accident scenario in order to calculate accident doses for HYLIFE-II. It consisted of a total loss of coolant accident (LOCA) in which all the liquid flibe (Li{sub 2}BeF{sub 4}) was lost at the beginning of the accident. Results showed that the off-site dose was below the limit given by the DOE Fusion Safety Standards for public protection in case of accident, and that his dose was dominated by the tritium released during the accident.
Date: October 11, 2000
Creator: Reyes, S; Latkowski, J F; Gomez del Rio, J & Sanz, J
Object Type: Article
System: The UNT Digital Library
Deflagration Behavior of PBXN-109 and Composition B at High Pressures and Temperatures (open access)

Deflagration Behavior of PBXN-109 and Composition B at High Pressures and Temperatures

We report deflagration rate measurements on PBXN-109 (RDWAVHTPB) and Composition B (RXDTTNThrvax) at pressures from 1,500-100,000 psi (10-700 MPa). This was done with the LLNL High Pressure Strand Burner, in which embedded wires are used to record the time-of-arrival of the burn front in the cylindrical sample as a function of pressure. The propellant samples are 6.4 mm in diameter and 6.4 mm long, with burn wires inserted between samples. Burning on the cylindrical surface is inhibited with an epoxy or polyurethane layer. With this direct measurement we do not have to account for product gas equation of state or heat losses in the system, and the burn wires allow detection of irregular burning. We report deflagration results for PBXN-109 as received, and also after it has been damaged by heating. The burn behavior of pristine PBXN-109 is very regular, and exhibits a reduction in pressure exponent from 1.32 to 0.85 at pressures above 20,000 psi (135 MPa). When PBXN-109 is thermally damaged by heating to 170-180 C, the deflagration rate is increased by more than a factor of 10. This appears to be a physical effect, as the faster burning may be explained by an increase in surface area. …
Date: March 11, 2002
Creator: Maienschein, J L & Wardell, J F
Object Type: Article
System: The UNT Digital Library
Highly Compressed Ion Beams for High Energy Density Science (open access)

Highly Compressed Ion Beams for High Energy Density Science

The Heavy Ion Fusion Virtual National Laboratory (HIFVNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target ''foils'', which may in fact be foams with mean densities 1% to 10% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the beam requirements for WDM experiments. We discuss neutralized drift compression and final focus experiments and modeling. We describe suitable accelerator architectures based on Drift-Tube Linac, RF, single-gap, Ionization-Front Accelerator, and Pulse-Line Ion Accelerator concepts. The last of these is being pursued experimentally in the HIF-VNL. Finally, we discuss plans toward a user facility for target experiments.
Date: May 11, 2005
Creator: Friedman, A.; Barnard, J. J.; Briggs, R. J.; Callahan, D. A.; Caporaso, G. J.; Celata, C. M. et al.
Object Type: Article
System: The UNT Digital Library
Discussion: Reporting and calibration of post-bomb 14C data (open access)

Discussion: Reporting and calibration of post-bomb 14C data

The definitive paper by Stuiver and Polach (1977) established the conventions for reporting of {sup 14}C data for chronological and geophysical studies based on the radioactive decay of {sup 14}C in the sample since the year of sample death or formation. Several ways of reporting {sup 14}C activity levels relative to a standard were also established, but no specific instructions were given for reporting nuclear weapons testing (post-bomb) {sup 14}C levels in samples. Because the use of post-bomb {sup 14}C is becoming more prevalent in forensics, biology, and geosciences, a convention needs to be adopted. We advocate the use of fraction modern with a new symbol F{sup 14}C to prevent confusion with the previously used Fm, which may or may not have been fractionation corrected. We also discuss the calibration of post-bomb {sup 14}C samples and the available datasets and compilations, but do not give a recommendation for a particular dataset.
Date: October 11, 2004
Creator: Reimer, P J; Brown, T A & Reimer, R W
Object Type: Article
System: The UNT Digital Library
Simulating Time-Dependent Energy Transfer Between Crossed Laser Beams in an Expanding Plasma (open access)

Simulating Time-Dependent Energy Transfer Between Crossed Laser Beams in an Expanding Plasma

A coupled mode system is derived to investigate a three-wave parametric instability leading to energy transfer between co-propagating laser beams crossing in a plasma flow. The model includes beams of finite width refracting in a prescribed transverse plasma flow with spatial and temporal gradients in velocity and density. The resulting paraxial light equations are discretized spatially with a Crank-Nicholson-type scheme, and these algebraic constraints are nonlinearly coupled with ordinary differential equations in time that describe the ion acoustic response. The entire nonlinear differential-algebraic system is solved using an adaptive, backward-differencing method coupled with Newton's method. A numerical study is conducted in two dimensions that compares the intensity gain of the fully time-dependent coupled mode system with the gain computed under the further assumption of a strongly-damped ion acoustic response. The results demonstrate a time-dependent gain suppression when the beam diameter is commensurate with the velocity gradient scale length. The gain suppression is shown to depend on time-dependent beam refraction and is interpreted as a time-dependent frequency shift.
Date: October 11, 2004
Creator: Hittinger, J. F.; Dorr, M. R.; Berger, R. L. & Williams, E. A.
Object Type: Article
System: The UNT Digital Library
Reference Artifacts for NDE (open access)

Reference Artifacts for NDE

Two reference artifacts will be fabricated for this study. One of the artifacts will have a cylindrical geometry and will contain features similar to those on an SNRT target. The second artifact will have a spherical geometry and will contain features similar to those on a Double Shell target. The artifacts were designed for manufacturability and to provide a range of features that can be measured using NDE methods. The cylindrical reference artifact is illustrated in Figure 1. This artifact consists of a polystyrene body containing two steps and a machined slot, into which will fit a tracer made of doped polystyrene. The polystyrene body contains several grooves and can be fabricated entirely on a diamond turning machine. The body can be machined by turning a PS rod to a diameter slightly greater than the finished diameter of 2 mm. The part can be moved off-axis to face it off and to machine the steps, slot, and grooves. The tracer contains a drilled hole and a milled slot, which could be machined with a single setup on a milling machine. Once assembled, the artifact could be placed in a Be tube or other structure relevant to target assemblies. The assembled …
Date: February 11, 2003
Creator: Bono, M.; Hibbard, R. & Martz, H. E.
Object Type: Report
System: The UNT Digital Library
Multiple Access in Ultra-Wideband Communications Using Multiple Pulses (open access)

Multiple Access in Ultra-Wideband Communications Using Multiple Pulses

Multiple access (MA) in UWB communication is an area of active research. To date several time-division or code-division pulse amplitude modulation (PAM) or pulse position modulation (PPM) schemes have been proposed to separate multiple users in UWB communications. Conventionally, all users employ the same pulse shape and modulate the transmit pulse based on changing amplitude or position. One concern with using the same pulse for all channels is that the multiple access interference (MAI) increases as the number of users increase. This is due to increased cross-correlation between similar pulses of the different channels, raising thus the noise floor in such systems. In this paper we introduce and study the performance of a new MA scheme in the context of multiple orthogonal transmitted-reference (T-R) short duration (nsec) chirp pulses in the presence of multipath and additive white Gaussian noise (AWGN).
Date: April 11, 2003
Creator: Nekoogar, F. & Dowla, F.
Object Type: Article
System: The UNT Digital Library
Cryogenic Facitlity Design in Bepc Ii Superconducting Upgrade. (open access)

Cryogenic Facitlity Design in Bepc Ii Superconducting Upgrade.

Three kinds of superconducting device are to be constructed at interaction regions in the upgrade of Beijing Electron-Positron Collider (BEPCII). Two sets of refrigerators with each capacity of 500W at 4.5K are adopted to provide the refrigeration for them. The cryogenic systems to support the operation of the superconducting facilities are under design by Harbin Institute of Technology in China. This paper presents the current design of main cryogenic facilities.
Date: May 11, 2004
Creator: Jia, L. X.; Wang, L.; Yang, G. D. & Al., Et
Object Type: Article
System: The UNT Digital Library
Fragmentation, Merging, and Internal Dynamics for PIC Simulation with Finite Size Particles (open access)

Fragmentation, Merging, and Internal Dynamics for PIC Simulation with Finite Size Particles

In plasma or rarified gas physics, collisions are rare but non-ignorable events. To model systems with arbitrary collisonality, it is necessary to start with a model that is fully capable of capturing collisionless, kinetic behavior. It is also necessary to build strategies to provide the essential economies into the scheme as collisions become more frequent. The desired model should progress smoothly and continuously from collisionless particle dynamics to collision-dominated fluid. We are developing a new approach [Hewett, JCP 2003; Larson, JCP 2003] to recover the physics of this partially collisional regime. Our approach, called CPK (for Collisional Particle Kinetics) is basically a ''smart particle'' PIC scheme with particles that have internal parameters representing internal ''fluid'' behavior as the CPK particles become large via merging. In the collisionless limit, the individual macro particles become numerous, small and cold through fragmentation--leading naturally to the traditional PIC limit. The new ''smart'' particle is a Gaussian distribution in all phase space directions. An arbitrary distribution of real particles can be made as a superposition of these ''particles''. One of the key capabilities is the ability to fragment each particle in a way that will not introduce new physics. With this procedure we can replace …
Date: August 11, 2003
Creator: Hewett, D. & Larson, D. J.
Object Type: Article
System: The UNT Digital Library
Hard X-ray Optics for Astronomy and the Laboratory (open access)

Hard X-ray Optics for Astronomy and the Laboratory

The hard X-ray regime (10-100 keV) remains one of the last unexplored areas of astronomy. During the next decade, several major observatories will open this new frontier, providing insight into black hole formation, nucleosynthesis and the physics that governs the most energetic quasars. The telescopes rely on grazing incidence optics coated with multilayers, and will require at wavelength calibration of the angular resolution of the mirrors and the reflectivity of their coatings-a task best performed at synchrotron facilities. As mirror fabrication and multilayer development for astronomy has progressed, other applications of these hard X-rays optics has emerged, ranging from radionuclide imaging for biomedical research to collimator optics for X-ray sources to target characterization and diagnostic imaging for the National Ignition Facility (NIF). The resolution, field of view (FOV) and throughput of these systems make them interesting candidates for adaptation to synchrotron beamlines, acting as collimator or collector elements or focusing elements for microscopy.
Date: October 11, 2004
Creator: Pivovaroff, M
Object Type: Article
System: The UNT Digital Library
Numerical Simulation on Thermal Stress and Magnetic Forces of Current Leads in Bepc Ii. (open access)

Numerical Simulation on Thermal Stress and Magnetic Forces of Current Leads in Bepc Ii.

Six pairs of low current leads are used for the superconducting interaction quadruple magnets (SCQ) in the Beijing Electron Positron Collider Upgrade (BEPCII). This paper presents analyses on the magnetic field induced by the current lead bundle as well as the magnetic forces on the leads. The thermal stress of the single lead is investigated. The stress of interference fitting for a novel insulator used for the current leads at various operating temperatures is analyzed.
Date: May 11, 2004
Creator: Zhang, X. B. & Jia, L. X.
Object Type: Article
System: The UNT Digital Library
Quality Control, Testing, and Deployment Results in the NIF ICCS (open access)

Quality Control, Testing, and Deployment Results in the NIF ICCS

The strategy used to develop the NIF Integrated Computer Control System (ICCS) calls for incremental cycles of construction and formal test to deliver a total of 1 million lines of code. Each incremental release takes four to six months to implement specific functionality and culminates when offline tests conducted in the ICCS Integration and Test Facility verify functional, performance, and interface requirements. Tests are then repeated on line to confirm integrated operation in dedicated laser laboratories or ultimately in the NIF. Test incidents along with other change requests are recorded and tracked to closure by the software change control board (SCCB). Annual independent audits advise management on software process improvements. Extensive experience has been gained by integrating controls in the prototype laser preamplifier laboratory. The control system installed in the preamplifier lab contains five of the ten planned supervisory subsystems and seven of sixteen planned front-end processors (FEPs). Beam alignment, timing, diagnosis and laser pulse amplification up to 20 joules was tested through an automated series of shots. Other laboratories have provided integrated testing of six additional FEPs. Process measurements including earned-value, product size, and defect densities provide software project controls and generate confidence that the control system will be …
Date: October 11, 2001
Creator: Woodruff, J P; Casavant, D; Cline, B D & Gorvad, M R
Object Type: Article
System: The UNT Digital Library