Laser Safety Inspection Criteria (open access)

Laser Safety Inspection Criteria

A responsibility of the Laser Safety Officer (LSO) is to perform laser safety audits. The American National Standard Z136.1 Safe use of Lasers references this requirement in several sections: (1) Section 1.3.2 LSO Specific Responsibilities states under Hazard Evaluation, ''The LSO shall be responsible for hazards evaluation of laser work areas''; (2) Section 1.3.2.8, Safety Features Audits, ''The LSO shall ensure that the safety features of the laser installation facilities and laser equipment are audited periodically to assure proper operation''; and (3) Appendix D, under Survey and Inspections, it states, ''the LSO will survey by inspection, as considered necessary, all areas where laser equipment is used''. Therefore, for facilities using Class 3B and or Class 4 lasers, audits for laser safety compliance are expected to be conducted. The composition, frequency and rigueur of that inspection/audit rests in the hands of the LSO. A common practice for institutions is to develop laser audit checklists or survey forms. In many institutions, a sole Laser Safety Officer (LSO) or a number of Deputy LSO's perform these audits. For that matter, there are institutions that request users to perform a self-assessment audit. Many items on the common audit list and the associated findings are …
Date: February 11, 2005
Creator: Barat, K.
Object Type: Article
System: The UNT Digital Library
Lessons Learned Class (open access)

Lessons Learned Class

Basic laser safety training at Lawrence Livermore National Laboratory (LLNL) is provided through a multiple module web-based course. The web-based course presents a wide and detailed review of laser safety topics including: biological effects, laser protective eyewear, fiber optic laser use, control measures, and more. It opens with a re-enactment of a laser accident. While supportive of this web-based course and actively involved in its development, the NIF Directorate has developed a classroom presentation adjunct to the course for laser users working in NIF. This author considers the LLNL web-based laser safety course to be one of, if not the best, such course available. Still, experience has shown that a ''lessons learned program'' is a great re-enforcer of laser safety. What-is-more, the laser lessons learned class provides important ''face-to-face'' interactions and discussion. The object of the ''laser lessons learned course'' is not to repeat the web course but present laser related lessons learned to the staff. In this author's opinion, lessons learned is the strongest safety re-enforcement one can present to the laser user community. For example, it can show how a practice that might be common to laser users can lead to a dramatic injury and a programmatic long-term …
Date: February 11, 2005
Creator: Barat, K.
Object Type: Article
System: The UNT Digital Library
Ab Initio Large-Basis No-Core Shell Model (open access)

Ab Initio Large-Basis No-Core Shell Model

We discuss the motivation, theory, and formulation of the ab initio No-Core Shell Model (NCSM). In this method the effective Hamiltonians are derived microscopically from realistic nucleon-nucleon (NN) and theoretical three-nucleon (NNN) potentials, as a function of the finite harmonic-oscillator (HO) basis space. We present converged results for the A = 3 and 4 nucleon systems, which are in agreement with results obtained by other exact methods, followed by results for p-shell nuclei. Binding energies, rms radii, excitation spectra, and electromagnetic properties are discussed.The favorable comparison with available data is a consequence of the underlying NN and NNN interactions rather than a phenomenological fit.
Date: February 11, 2005
Creator: Barrett, B R; Navratil, P; Nogga, A; Ormand, W E; Stetcu, I; Vary, J P et al.
Object Type: Article
System: The UNT Digital Library
Neutron Transmission and Capture Measurements and Resonance Parameter Analysis of Neodymium from 1eV to 500 eV (open access)

Neutron Transmission and Capture Measurements and Resonance Parameter Analysis of Neodymium from 1eV to 500 eV

None
Date: February 11, 2005
Creator: Barry, DP; Trbovich, MJ; Danon, Y; Block, RC & Slovacek, RE
Object Type: Article
System: The UNT Digital Library
Sensitivity and Uncertainty Analysis to Burn-up Estimates on ADS Using ACAB Code (open access)

Sensitivity and Uncertainty Analysis to Burn-up Estimates on ADS Using ACAB Code

Within the scope of the Accelerator Driven System (ADS) concept for nuclear waste management applications, the burnup uncertainty estimates due to uncertainty in the activation cross sections (XSs) are important regarding both the safety and the efficiency of the waste burning process. We have applied both sensitivity analysis and Monte Carlo methodology to actinides burnup calculations in a lead-bismuth cooled subcritical ADS. The sensitivity analysis is used to identify the reaction XSs and the dominant chains that contribute most significantly to the uncertainty. The Monte Carlo methodology gives the burnup uncertainty estimates due to the synergetic/global effect of the complete set of XS uncertainties. These uncertainty estimates are valuable to assess the need of any experimental or systematic reevaluation of some uncertainty XSs for ADS.
Date: February 11, 2005
Creator: Cabellos, O; Sanz, J; Rodriguez, A; Gonzalez, E; Embid, M; Alvarez, F et al.
Object Type: Article
System: The UNT Digital Library
Development of a Chemoenzymatic-like and Photoswitchable Method for the Ordered Attachment of Proteins to Surfaces (open access)

Development of a Chemoenzymatic-like and Photoswitchable Method for the Ordered Attachment of Proteins to Surfaces

Protein arrays are the best tool for the rapid analysis of a whole proteome thus helping to identify all the protein/protein interactions in a living cell and they can also be used as powerful biosensors. The objective of this proposal is to develop a new entropically activated ligation method based in the naturally occurring protein trans-splicing process. This method will be used for the generation of spatially addressable arrays of multiple protein components by standard photolithographic techniques. Key to our approach is the use of the protein trans-splicing process. This naturally occurring process will allow us to create a truly generic and highly efficient method for the covalent attachment of proteins through its C-terminus to any solid support.
Date: February 11, 2005
Creator: Camarero, J A; Kwon, Y & Coleman, M
Object Type: Report
System: The UNT Digital Library
MPI Profiling (open access)

MPI Profiling

The Message Passing Interface (MPI) is the de facto message-passing standard for massively parallel programs. It is often the case that application performance is a crucial factor, especially for solving grand challenge problems. While there have been many studies on the scalability of applications, there have not been many focusing on the specific types of MPI calls being made and their impact on application performance. Using a profiling tool called mpiP, a large spectrum of parallel scientific applications were surveyed and their performance results analyzed.
Date: February 11, 2005
Creator: Han, D K & Jones, T R
Object Type: Report
System: The UNT Digital Library
Report on Toyota Prius Motor Thermal Management (open access)

Report on Toyota Prius Motor Thermal Management

In the current hybrid vehicle market, the Toyota Prius drive system is considered the leader in electrical, mechanical, and manufacturing innovations. It is a significant accomplishment that Toyota is able to manufacture and sell the vehicle for a profit. The Toyota Prius traction motor design approach for reducing manufacturing costs and the motor s torque capability have been studied and tested. The findings were presented in two previous Oak Ridge National Laboratory (ORNL) reports. The conclusions from this report reveal, through temperature rise tests, that the 2004 Toyota Prius (THSII) motor is applicable only for use in a hybrid automobile. It would be significantly undersized if used in a fuel cell vehicle application. The power rating of the Prius motor is limited by the permissible temperature rise of the motor winding (170 C) and the motor cooling oil (158 C). The continuous ratings at base speed (1200 rpm) with different coolant temperatures are projected from test data at 900 rpm. They are approximately 15 kW with 105 C coolant and 21 kW with 35 C coolant. These continuous ratings are much lower than the 30 kW specified as a technical motor target of the U.S. Department of Energy FreedomCAR Program. …
Date: February 11, 2005
Creator: Hsu, J.S.
Object Type: Report
System: The UNT Digital Library
Photoinduced Electron Transfer in Ordered Macromolecular Assemblies. Final report for May 1, 1988 - June 30, 2002 (open access)

Photoinduced Electron Transfer in Ordered Macromolecular Assemblies. Final report for May 1, 1988 - June 30, 2002

The final report describes studies over a 13 year period having to do with photoinduced electron transfer for active chromophores and redox agents, including assembly of the components in water soluble polymers or polypeptides. The findings include observation of long range charge separation and electron transport using laser phototransient spectroscopy. The systems targeted in these studies include peptide assemblies for which helical conformations and aggregation are documented. Oligomeric peptides modified with non-native redox active groups were also selected for investigation. Highly charged polymers or peptides were investigated as host agents that resemble proteins. The overall goal of these investigations focused on the design and characterization of systems capable of artificial photosynthesis.
Date: February 11, 2005
Creator: Jones, G.
Object Type: Report
System: The UNT Digital Library
Final Report LDRD 02-ERD-013 Dense Plasma Characterization by X-ray Thomson Scattering (open access)

Final Report LDRD 02-ERD-013 Dense Plasma Characterization by X-ray Thomson Scattering

We have successfully demonstrated spectrally-resolved x-ray scattering in a variety of dense plasmas as a powerful new technique for providing microscopic dense plasma parameters unattainable by other means. The results have also been used to distinguish between ionization balance models. This has led to 10 published or to be published papers, 8 invited talks and significant interest from both internal and external experimental plasma physicists and the international statistical plasma physics theory community.
Date: February 11, 2005
Creator: Landen, O L; Glenzer, S H; Gregori, G; Pollaine, S M; Hammer, J H; Rogers, F et al.
Object Type: Report
System: The UNT Digital Library

The US Department of Energy Joint Genome Institute MicrobialGenome Program

None
Date: February 11, 2005
Creator: Lapidus, Alla
Object Type: Presentation
System: The UNT Digital Library
Mitigation of CBRN Incidents for HVAC Systems in Federal Facilities (open access)

Mitigation of CBRN Incidents for HVAC Systems in Federal Facilities

None
Date: February 11, 2005
Creator: MacDonald, JM
Object Type: Report
System: The UNT Digital Library
Data from deployment of temporary seismic stations in northern Norway and Finland (open access)

Data from deployment of temporary seismic stations in northern Norway and Finland

This short contribution is a description of data now available in NORSAR's data archives from a temporary deployment during 2002-2004 of six seismic stations in northern Norway and Finland. Explosions in underground as well as open-pit mines in the Khibiny massif of the Kola Peninsula of northwestern Russia are conducted on a frequent and relatively regular basis. It was decided to supplement the network of permanent stations in northern Fennoscandia and northwest Russia with temporarily deployed stations, in order to record these explosions, as well as other mining explosions and natural events occurring in this general area. As shown in Fig. 6.4.1, the six temporary stations were deployed along two profile lines, extending westwards from the Khibini massif. The rationale for this deployment was to collect data to examine distance as well as azimuthal dependence of seismic discriminants. As can be seen from Fig. 6.4.1 the southernmost of the two profile lines runs through the permanent seismic array ARCES in northern Norway.
Date: February 11, 2005
Creator: Maercklin, N; Mykkeltveit, S; Schweitzer, J; Harris, D B & Rock, D W
Object Type: Report
System: The UNT Digital Library
Electronic transport through carbon nanotubes - effect of contacts, topological defects, dopants and chemisorbed impurities (open access)

Electronic transport through carbon nanotubes - effect of contacts, topological defects, dopants and chemisorbed impurities

Electronics based on carbon nanotubes (CNT) has received a lot of attention recently because of its tremendous application potential, such as active components and interconnects in nanochips, nanoelectromechanical systems (NEMS), display devices, and chemical and biological sensors. However, as with most nanoelectronic systems, successful commercial deployment implies structural control at the molecular level. To this end, it is clearly necessary to understand the effect of contacts, topological defects, dopants, and chemisorbed atoms and molecules on the electronic transport through CNT's. This paper summarizes our computational efforts to address some of the above questions. Examples include: wetting properties and bonding strength of metal contacts on the CNT surface, the effect of Stone-Wales defects on the chemisorption of O{sub 2} and NH3, and how such chemisorbed species and defects effect the electronic transmission and conductance. Our approach is based on first-principles density functional theory (DFT) to compute equilibrium structures, and nonequilibrium Green's function (NEGF) methods, using both DFT and semi-empirical tight-binding formalisms, for computing electronic transport properties.
Date: February 11, 2005
Creator: Maiti, A.; Hoekstra, J.; Andzelm, J.; Govind, N.; Ricca, A.; Svizhenko, A. et al.
Object Type: Article
System: The UNT Digital Library
Recent Applications of Mesoscale Modeling to Nanotechnology and Drug Delivery (open access)

Recent Applications of Mesoscale Modeling to Nanotechnology and Drug Delivery

Mesoscale simulations have traditionally been used to investigate structural morphology of polymer in solution, melts and blends. Recently we have been pushing such modeling methods to important areas of Nanotechnology and Drug delivery that are well out of reach of classical molecular dynamics. This paper summarizes our efforts in three important emerging areas: (1) polymer-nanotube composites; (2) drug diffusivity through cell membranes; and (3) solvent exchange in nanoporous membranes. The first two applications are based on a bead-spring-based approach as encoded in the Dissipative Particle Dynamics (DPD) module. The last application used density-based Mesoscale modeling as implemented in the Mesodyn module.
Date: February 11, 2005
Creator: Maiti, A.; Wescott, J.; Kung, P. & Goldbeck-Wood, G.
Object Type: Article
System: The UNT Digital Library
FY04 LDRD Final Report Small Sample Heat Capacity Under High Pressure LDRD Project Tracking Code: 04-FS-020 (open access)

FY04 LDRD Final Report Small Sample Heat Capacity Under High Pressure LDRD Project Tracking Code: 04-FS-020

Specific heat provides a probe of bulk thermodynamic properties, including low energy excitations (phonons, magnons, etc), the electron density of states, and direct observation of phase transitions. The ability to measure specific heat as a function of pressure permits study of these properties as a function of lattice parameters. This in turn should allow construction of an equation of state for a given system. Previous measurements of specific heat under pressure done by adiabatic methods were limited to materials with extremely large heat capacities because it was difficult to decouple the sample heat capacity from the surrounding pressure cell. Starting in the late Seventies, Eichler and Gey[1] demonstrated an AC technique to measure heat capacity of relatively small samples ({approx}100's mg) in a piston pressure cylinder at pressures up to 2 GPa. More recently, this technique has been expanded to include work on significantly smaller samples (< 1mg) in large diamond anvil cells (DAC)[2]. However, these techniques require a relatively weak coupling of the sample to the surrounding thermal bath, which limits the base temperature, particularly for radioactive samples possessing significant self-heating such as plutonium. A different technique, sometimes referred to as the 3{omega}-technique, utilizes a two dimensional heat flow …
Date: February 11, 2005
Creator: McCall, S. K. & Jackson, D. D.
Object Type: Report
System: The UNT Digital Library
A Numerical Study of On-Axis Dose Rate from Ta and W Bremsstrahlung Converter Targets (open access)

A Numerical Study of On-Axis Dose Rate from Ta and W Bremsstrahlung Converter Targets

The bremsstrahlung converter target in radiographic accelerators is not, in general, considered a high-technology piece of equipment. In its essential form it is merely a solid plate of high-Z metal, usually tungsten (W) or tantalum (Ta); electrons go in, X-rays come out [1]. However, there are some important factors to keep in mind for this kind of target system. One is a constraint on the target itself: the proper thickness of material. Too little material reduces the probability that an electron will have a significant nuclear collision before exiting the plate. Too much material has a number of effects: small-angle scattering will occur to such an extent that bremsstrahlung photons will not be pointed in the forward direction. Electrons which small-angle scatter away and then back to the forward direction will have moved to larger radii as they traverse the target, increasing the effective source size. Electrons ''backscattered'' from the target --primaries or secondaries ejected from the upstream surface after sufficient angular scatter--exert a defocusing force on the incoming beam due to increased space charge at fixed (or even slightly reduced) current. Finally, a sufficiently thick target will begin to self-attenuate the X-ray photons produced in the upstream portion of …
Date: February 11, 2005
Creator: McCarrick, J F
Object Type: Report
System: The UNT Digital Library
Radial-Gap Permanent Magnet Motor and Drive Research FY 2004 (open access)

Radial-Gap Permanent Magnet Motor and Drive Research FY 2004

The objective of this task was to study permanent magnet (PM) radial-gap traction drive systems that could meet the U.S. Department of Energy FreedomCAR Program's 2010 goals to expose weaknesses or identify strengths. Initially, the approach was to compare attributes such as physical deformations during operation, performance (torque, power, efficiency versus speed), material requirements (strength), material costs, manufacturability, weight, power density, specific power, reliability, and drivability for specific motors. Three motors selected were the commercially available 60-kW radial-gap surface-mounted PM motor manufactured by UQM Technologies, Inc.; a hypothetical PM motor with rotor-supported magnets similar to the Honda MCF-21; and Delphi's automotive electric machine drive motor, whose rotor is a ferromagnetic cylinder, held at one end by a shaft that supports the magnets on its inner surface. Potential problems have appeared related to PM motors, such as (1) high no-load spin losses and high operational power losses, probably from eddy current losses in the rotor; (2) the undemonstrated dual mode inverter control (DMIC) for driving a brushless dc motor (BDCM) (UQM and Delphi motors); (3) uncertainty about the potential for reducing current with DMIC; and (4) uncertainty about the relation between material requirements and maximum rotor speed. Therefore, the approach was …
Date: February 11, 2005
Creator: McKeever, J.W.
Object Type: Report
System: The UNT Digital Library
Plasma interferometry and how the bound electron contribution can bend fringes in unexpected ways (open access)

Plasma interferometry and how the bound electron contribution can bend fringes in unexpected ways

For decades the measurement of the electron density in plasmas by interferometers has relied on the approximation that the index of refraction in a plasma is due solely to the free electrons and therefore is less than one. Recent measurements of Al plasmas using X-ray laser interferometers have observed anomalous results with the fringes bending the opposite way than expected due to the index of refraction being larger than one. Subsequent analysis showed that the bound electrons have a larger contribution to the index of refraction with the opposite sign than the free electrons. This effect extends far from the absorption edges and lines of the bound electrons. Utilizing a new average atom code we calculate the index of refraction in C, Al, Ti and Pd plasmas and show that there are many conditions over which the bound electron contribution dominates as we explore photon energies from the optical to 100 eV (12 nm) soft X-rays. During the next decade X-ray free electron lasers and other sources will be available to probe a wider variety of plasmas at higher densities and shorter wavelengths so understanding the index of refraction in plasmas will be even more essential.
Date: February 11, 2005
Creator: Nilsen, J & Johnson, W R
Object Type: Article
System: The UNT Digital Library
Analysis of High Power IGBT Short Circuit Failures (open access)

Analysis of High Power IGBT Short Circuit Failures

The Next Linear Collider (NLC) accelerator proposal at SLAC requires a highly efficient and reliable, low cost, pulsed-power modulator to drive the klystrons. A solid-state induction modulator has been developed at SLAC to power the klystrons; this modulator uses commercial high voltage and high current Insulated Gate Bipolar Transistor (IGBT) modules. Testing of these IGBT modules under pulsed conditions was very successful; however, the IGBTs failed when tests were performed into a low inductance short circuit. The internal electrical connections of a commercial IGBT module have been analyzed to extract self and mutual partial inductances for the main current paths as well as for the gate structure. The IGBT module, together with the partial inductances, has been modeled using PSpice. Predictions for electrical paths that carry the highest current correlate with the sites of failed die under short circuit tests. A similar analysis has been carried out for a SLAC proposal for an IGBT module layout. This paper discusses the mathematical model of the IGBT module geometry and presents simulation results.
Date: February 11, 2005
Creator: Pappas, G.
Object Type: Report
System: The UNT Digital Library
NOx Reduction with Natural Gas for Lean Large-Bore Engine Applications Using Lean NOx Trap Aftertreatment (open access)

NOx Reduction with Natural Gas for Lean Large-Bore Engine Applications Using Lean NOx Trap Aftertreatment

Large-bore natural gas engines are used for distributed energy and gas compression since natural gas fuel offers a convenient and reliable fuel source via the natural gas pipeline and distribution infrastructure. Lean engines enable better fuel efficiency and lower operating costs; however, NOx emissions from lean engines are difficult to control. Technologies that reduce NOx in lean exhaust are desired to enable broader use of efficient lean engines. Lean NOx trap catalysts have demonstrated greater than 90% NOx reduction in lean exhaust from engines operating with gasoline, diesel, and natural gas fuels. In addition to the clean nature of the technology, lean NOx traps reduce NOx with the fuel source of the engine thereby eliminating the requirement for storage and handling of secondary fuels or reducing agents. A study of lean NOx trap catalysts for lean natural gas engines is presented here. Testing was performed on a Cummins C8.3G (CG-280) engine on a motor dynamometer. Lean NOx trap catalysts were tested for NOx reduction performance under various engine operating conditions, and the utilization of natural gas as the reductant fuel source was characterized. Engine test results show that temperature greatly affects the catalytic processes involved, specifically methane oxidation and NOx …
Date: February 11, 2005
Creator: Parks, J. E.
Object Type: Report
System: The UNT Digital Library
D-Area Sulfate Reduction Studty Comprehensive Final Report (open access)

D-Area Sulfate Reduction Studty Comprehensive Final Report

An acidic/metals/sulfate, groundwater contaminant plume emanates from the D-Area Coal Pile Runoff Basin (DCPRB) at the Savannah River Site (SRS), due to the contaminated runoff the basin receives from the D-Area coal pile. A Treatability Study Work Plan (TSWP) (WSRC 2001) was implemented to evaluate the potential for the sulfate reduction remediation of the DCPRB acidic/metals/sulfate, groundwater contaminant plume. The following studies, implemented as part of the TSWP, are documented herein: Bacteria Population and Organic Selection Laboratory Testing; DTT-1 Trench Evaluation; DIW-1 Organic Application Field Study-Part 1; and DIW-1 Organic Application Field Study-Part 2. Evaluation of sulfate reduction applicability actually began with a literature search and feasibility report in mid 2001, which fed into the TSWP. Physical completion of TSWP work occurred in late 2004 with the completion of the DIW-1 Organic Application Field Study-Part 2. The following are the primary conclusions drawn based upon this 3-year effort: (1) Pure soybean oil provides a long-term, indirect, SRB carbon source that floats on top of the water table (by indirect it means that the soybean oil must be degraded by other microbes prior to utilization by SRB) for the promotion of sulfate reduction remediation. Soybean oil produces no known SRB inhibitory …
Date: February 11, 2005
Creator: Phifer, M
Object Type: Report
System: The UNT Digital Library
Electron-wall Interaction in Hall Thrusters (open access)

Electron-wall Interaction in Hall Thrusters

Electron-wall interaction effects in Hall thrusters are studied through measurements of the plasma response to variations of the thruster channel width and the discharge voltage. The discharge voltage threshold is shown to separate two thruster regimes. Below this threshold, the electron energy gain is constant in the acceleration region and therefore, secondary electron emission (SEE) from the channel walls is insufficient to enhance electron energy losses at the channel walls. Above this voltage threshold, the maximum electron temperature saturates.
Date: February 11, 2005
Creator: Raitses, Y.; Staack, D.; Keidar, M. & Fisch, N.J.
Object Type: Report
System: The UNT Digital Library
Long Time-Scale Atomistic Simulations (open access)

Long Time-Scale Atomistic Simulations

During the past two years, we have succeeded in implementing an efficient parallel Importance Sampling Monte-Carlo (ISMC) scheme with application towards rarely occurring transition events, of great abundance in materials science and chemistry. The inefficiency of the standard atomistic modeling techniques for these problems may be traced to the extremely low probability of sampling system trajectories, or paths, that lead to a successful transition event. Instead of following the conventional approach of developing smart algorithms for searching transition paths, we tackle this problem by explicitly enhancing the probability of sampling successful transition events by means of an importance function. By selecting it appropriately, one focuses predominantly on the successful transition paths while discarding most irrelevant ones. In this manner, the rare-event problem is reformulated into an optimization problem for finding the best-possible importance function. Utilizing efficient iterative minimization algorithms, our IS approach can now be used to calculate the rate of occurrence of low-probability transition phenomena of short duration (short successful paths), but which involve collective degrees of freedom of many atoms.
Date: February 11, 2005
Creator: Sadigh, B; Cai, W; de Koning, M; Oppelstrup, T; Bulatov, V & Kalos, M
Object Type: Report
System: The UNT Digital Library