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Advanced Thermometrics for Fossil Power Plant Process Improvement (open access)

Advanced Thermometrics for Fossil Power Plant Process Improvement

Improved temperature measurements in fossil power plants can reduce heat rate and uncertainties in power production efficiencies, extend the life of plant components, reduce maintenance costs, and lessen emissions. Conventional instruments for measurement of combustion temperatures, steam temperatures, and structural component temperatures can be improved by better specification, in situ calibration, signal processing, and performance monitoring. Innovative instruments can enhance, augment, or replace conventional instruments. Several critical temperatures can be accessed using new methods that were impossible with conventional instruments. Such instruments include high temperature resistance temperature detectors (RTDs), thermometric phosphors, inductive thermometry, and ultrasonic thermometry.
Date: April 30, 1996
Creator: Shepard, R. L.; Weiss, J. M. & Holcomb, D. E.
System: The UNT Digital Library
A data analysis routine to protect confidential information during GC-MS analysis (open access)

A data analysis routine to protect confidential information during GC-MS analysis

The Chemical Weapons Convention allows for the collection and analysis of samples at inspection sites, including demilitarization facilities, to verify compliance with treaty obligations. The Preparatory Commission to the OPCW, through its Expert Group on Inspection Procedures, PC-VIII/B/WP.2, has determined that the Technical Secretariat must have analytical equipment that among other things, allows {open_quotes}identification and recording of the detection of chemicals relevant to the purpose of the inspection, but the suppression of the indication and recording of the detection of chemicals and other information unrelated to the purpose of the inspection.{close_quotes} This paper describes unfinished work at the Lawrence Livermore National Laboratory (LLNL) to satisfy this requirement for GC-MS instrumentation.
Date: April 30, 1996
Creator: McGuire, R. R. & Martin, W. H.
System: The UNT Digital Library
The path to the future: The role of science and technology at Argonne National Laboratory (open access)

The path to the future: The role of science and technology at Argonne National Laboratory

Today some scientists are concerned that present budget considerations in Washington will make it impossible for the US to maintain its preeminence in important areas of science and technology. In the private sector there has been a demise of substantive R & D efforts through most of the major industries. For DOE a lack of future support for science and technology would be an important issue because this could impact DOE`s abilities to solve problems in its major areas of concern, national security, energy, environment. In fact some scientists maintain that were the present trend to continue unabated it could lead to a national security issue. Preeminence in science and technology plays a critical role in our nation`s position as the leader of world democracy. In contrast with this point of view of gloom and doom, however, in this presentation I hope to bring to you what I see as an exciting message of good news. Today I will list the important opportunities and challenges for the future that I note for ANL, the leadership role that I believe ANL can play and the qualities that will help our laboratory to maintain its status as an outstanding DOE National Laboratory.
Date: April 30, 1996
Creator: Reck, R.A.
System: The UNT Digital Library
Eliminating the possibility at Chernobyl 4 of recriticality with positive feedback (open access)

Eliminating the possibility at Chernobyl 4 of recriticality with positive feedback

We have recently published an article in which we discuss means by which plutonium and other fissile material stored underground could reach criticality with positive feedback and therefore explosive potential. The Chernobyl rubble involving hundreds of tons of material is similar in some respects to the systems analyzed in the paper, and the practices there to control criticality may well increase the probability of a second event at Chernobyl 4. This paper explores the Chernobyl situation and remedial actions are recommended.
Date: April 29, 1996
Creator: Bowman, C. D.
System: The UNT Digital Library
Neutron activation for ITER (open access)

Neutron activation for ITER

There are three primary goals for the Neutron Activation system for ITER: maintain a robust relative measure of fusion power with stability and high dynamic range (7 orders of magnitude); allow an absolute calibration of fusion power (energy); and provide a flexible and reliable system for materials testing. The nature of the activation technique is such that stability and high dynamic range can be intrinsic properties of the system. It has also been the technique that demonstrated (on JET and TFTR) the highest accuracy neutron measurements in DT operation. Since the gamma-ray detectors are not located on the tokamak and are therefore amenable to accurate characterization, and if material foils are placed very close to the ITER plasma with minimum scattering or attenuation, high overall accuracy in the fusion energy production (7--10%) should be achievable on ITER. In the paper, a conceptual design is presented. A system is shown to be capable of meeting these three goals, also detailed design issues remain to be solved.
Date: April 29, 1996
Creator: Barnes, C. W.; Loughlin, M. J. & Nishitani, Takeo
System: The UNT Digital Library
Fabrication of large aperture kinoform phase plates in fused silica for smoothing focal plane intensity profiles (open access)

Fabrication of large aperture kinoform phase plates in fused silica for smoothing focal plane intensity profiles

We have fabricated large aperture (40-cm) kinoform phase plates for producing super-Gaussian focal plane intensity profiles. The continuous phase screen, designed using a new iterative procedure, was fabricated in fused silica as a 16-level, one-wave deep rewrapped phase profile using a lithographic process and wet etching in buffered hydrofluoric acid. The observed far-field contains 94% of the incident energy inside the desired spot.
Date: April 26, 1996
Creator: Rushford, M.; Dixit, S.; Thomas, I. & Perry, M.
System: The UNT Digital Library
Large area damage testing of optics (open access)

Large area damage testing of optics

The damage threshold specifications for the National Ignition Facility will include a mixture of standard small-area tests and new large-area tests. During our studies of laser damage and conditioning processes of various materials we have found that some damage morphologies are fairly small and this damage does not grow with further illumination. This type of damage might not be detrimental to the laser performance. We should therefore assume that some damage can be allowed on the optics, but decide on a maximum damage allowance of damage. A new specification of damage threshold termed {open_quotes}functional damage threshold{close_quotes} was derived. Further correlation of damage size and type to system performance must be determined in order to use this measurement, but it is clear that it will be a large factor in the optics performance specifications. Large-area tests have verified that small-area testing is not always sufficient when the optic in question has defect-initiated damage. This was evident for example on sputtered polarizer and mirror coatings where the defect density was low enough that the features could be missed by standard small- area testing. For some materials, the scale-length at which damage non-uniformities occur will effect the comparison of small-area and large-area tests. …
Date: April 26, 1996
Creator: Sheehan, L.; Kozlowski, M. & Stolz, C.
System: The UNT Digital Library
Synthesis of fully continuous phase screens for tailoring the focal plane irradiance profiles (open access)

Synthesis of fully continuous phase screens for tailoring the focal plane irradiance profiles

We present an iterative procedure for constructing fully continuous phase screens for tailoring the focal plane intensity distributions. This algorithm alleviates the stagnations experienced in the application of the Gerchberg-Saxton algorithm with a random initial phase screen and leads to efficient distribution of the incident energy into the desired focal plane profile.
Date: April 26, 1996
Creator: Dixit, S. & Feit, M.
System: The UNT Digital Library
Diamond switches for high temperature electronics (open access)

Diamond switches for high temperature electronics

Diamond switches are well suited for use in high temperature electronics. Laboratory feasibility of diamond switching at 1 kV and 18 A was demonstrated. DC blocking voltages up to 1 kV were demonstrated. A 50 {Omega} load line was switched using a diamond switch, with switch on-state resistivity {approx}7 {Omega}-cm. An electron beam, {approx}150 keV energy, {approx}2 {mu}s full width at half maximum was used to control the 5 mm x 5 mm x 100 {mu}m thick diamond switch. The conduction current temporal history mimics that of the electron beam. These data were taken at room temperature.
Date: April 25, 1996
Creator: Prasad, R. R.; Rondeau, G. & Qi, Niansheng
System: The UNT Digital Library
Can the multianvil apparatus really be used for high-pressure deformation experiments? (open access)

Can the multianvil apparatus really be used for high-pressure deformation experiments?

Past claims of the suitability of the MA-8 multianvil press as a deformation apparatus may have been overstated. On the basis of measurements of final octahedron size and of guide block displacement as a function of time, using the 10/5, 14/8, and 18/11 assemblies (octahedron edge length in mm/truncation edge length in mm) with MgO octahedra and pyrophyllite gasketing, it appears that at run conditions of interest to most researchers there is no appreciable time-dependent creep of gaskets and octahedra. All inelastic deformation occurs at rather low pressures: below about 10 GPa for the 10/5, 7 GPa for the 14/8, and 6 GPa for the 18/11 assemblies, with substantial uncertainties in these pressures. Above these limits all deformation of the pressure medium is elastic. Pressure stepping as a means of increasing the inelastic deformation rate of a sample is probably ineffective. Displacement measured at the guide blocks, previously believed to indicate deformation of the gaskets and octahedron, appears now to be unrelated to creep of these components. The calibrations have not been exhaustive and there is considerable scatter in some of the size measurements, so the above conclusions are not unequivocal. The calibrations do not exclude the possibility of deformation …
Date: April 24, 1996
Creator: Durham, W.B. & Rubie, D.C.
System: The UNT Digital Library
Spectroscopic temperature measurements of non-equilibrium plasmas (open access)

Spectroscopic temperature measurements of non-equilibrium plasmas

The characterization of laser-produced plasmas has required the application of spectroscopic techniques to non-standard conditions where kinetics models have not been extensively tested. The plasmas are produced by the Nova laser for the study of inertial confinement fusion, can be mm in size, and evolve on sub-nanosecond time scales. These targets typically achieve electron temperatures from 2-4 keV and electron densities of 10{sup 20}-10{sup 22} cm{sup {minus}3}. The authors have measured the electron temperature of two types of targets: bags of gas and hohlraums, Au cylinders with laser entrance holes in the flat ends. By comparing data from different targets, they examine the time-dependence of spectroscopic plasma diagnostics.
Date: April 24, 1996
Creator: Back, C. A.; Glenzer, S. H.; Lee, R. W. & MacGowan, B. J.
System: The UNT Digital Library
Multiple mechanisms of thermally activated plastic flow in shocked and unshocked tantalum (open access)

Multiple mechanisms of thermally activated plastic flow in shocked and unshocked tantalum

We argue that the principal features of the plastic flow behavior of tantalum can be described by a model that incorporates a two-component Peierls-type mechanism and an {open_quotes}obstacle{close_quotes} mechanism in series. We compare the results of calculations based on such a model with flow data for unalloyed tantalum before and after shock loading to 38 GPa for 1 {mu}s. Our data suggest that the shock loading changes only structural parameters.
Date: April 22, 1996
Creator: Gourdin, W.H. & Lassila, D.H.
System: The UNT Digital Library
Multiple mechanisms of thermally activated plastic flow in shocked and unshocked tantalum. Revision 1 (open access)

Multiple mechanisms of thermally activated plastic flow in shocked and unshocked tantalum. Revision 1

We argue that the principal features of the plastic flow behavior of Ta can be described a model that incorporates a two-component Peierls-type mechanism and an ``obstacle`` mechanism in series. We compare results of calculations based on such a model with flow data for unalloyed Ta before and after shock loading to 45 GPa for 1.8 {mu}s. Our data suggest that the shock loading changes only structural parameters.
Date: April 22, 1996
Creator: Gourdin, W.H. & Lassila, D.H.
System: The UNT Digital Library
Power spectral density specifications for high-power laser systems (open access)

Power spectral density specifications for high-power laser systems

This paper describes the use of Fourier techniques to characterize the transmitted and reflected wavefront of optical components. Specifically, a power spectral density, (PSD), approach is used. High power solid-state lasers exhibit non-linear amplification of specific spatial frequencies. Thus, specifications that limit the amplitude of these spatial frequencies are necessary in the design of these systems. Further, NIF optical components have square, rectangular or irregularly shaped apertures with major dimensions up-to 800 mm. Components with non-circular apertures can not be analyzed correctly with Zernicke polynomials since these functions are an orthogonal set for circular apertures only. A more complete and powerful representation of the optical wavefront can be obtained by Fourier analysis in 1 or 2 dimensions. The PSD is obtained from the amplitude of frequency components present in the Fourier spectrum. The shape of a resultant wavefront or the focal spot of a complex multicomponent laser system can be calculated and optimized using PSDs of the individual optical components which comprise the system. Surface roughness can be calculated over a range of spatial scale-lengths by integrating the PSD. Finally, since the optical transfer function (OTF) of the instruments used to measure the wavefront degrades at high spatial frequencies, the …
Date: April 22, 1996
Creator: Lawson, J. K.; Aikens, D. A.; English, R. E., Jr. & Wolfe, C. R.
System: The UNT Digital Library
Crystalline structure in the confined-deconfined mixed phase: Neutron stars as an example (open access)

Crystalline structure in the confined-deconfined mixed phase: Neutron stars as an example

We review the differences in first order phase transition of single and multi-component systems, and then discuss the crystalline structure expected to exist in the mixed confined deconfined phase of hadronic matter. The particular context of neutron stars is chosen for illustration. The qualitative results are general and apply for example to the vapor-liquid transition in subsaturated asymmetric nuclear matter.
Date: April 18, 1996
Creator: Glendenning, N.K.
System: The UNT Digital Library
Environmental waste site characterization utilizing aerial photographs, remote sensing, and surface geophysics (open access)

Environmental waste site characterization utilizing aerial photographs, remote sensing, and surface geophysics

Six different techniques were used to delineate 40 year old trench boundary at Los Alamos National Laboratory. Data from historical aerial photographs, a magnetic gradient survey, airborne multispectral and thermal infra-red imagery, seismic refraction, DC resistivity, and total field magnetometry were utilized in this process. Each data set indicated a southern and northern edge for the trench. Average locations and 95% confidence limits for each edge were determined along a survey line perpendicular to the trench. Trench edge locations were fairly consistent among all six techniques. Results from a modeling effort performed with the total magnetic field data was the least consistent. However, each method provided unique and complementary information, and the integration of all this information led to a more complete characterization of the trench boundaries and contents.
Date: April 18, 1996
Creator: Pope, P.; Van Eeckhout, E.; Rofer, C.; Baldridge, S.; Ferguson, J.; Jiracek, G. et al.
System: The UNT Digital Library
A technique for determining the Poisson`s ratio of thin films (open access)

A technique for determining the Poisson`s ratio of thin films

The theory and experimental approach for a new technique used to determine the Poisson`s ratio of thin films are presented. The method involves taking the ratio of curvatures of cantilever beams and plates micromachined out of the film of interest. Curvature is induced by a through-thickness variation in residual stress, or by depositing a thin film under residual stress onto the beams and plates. This approach is made practical by the fact that the two curvatures air, the only required experimental parameters, and small calibration errors cancel when the ratio is taken. To confirm the accuracy of the technique, it was tested on a 2.5 {mu}m thick film of single crystal silicon. Micromachined beams 1 mm long by 100 {mu} wide and plates 700 {mu}m by 700 {mu}m were coated with 35 nm of gold and the curvatures were measured with a scanning optical profilometer. For the orientation tested ([100] film normal, [011] beam axis, [0{bar 1}1] contraction direction) silicon`s Poisson`s ratio is 0.064, and the measured result was 0.066 {+-} 0.043. The uncertainty in this technique is due primarily to variation in the measured curvatures, and should range from {+-} 0.02 to 0.04 with proper measurement technique.
Date: April 18, 1996
Creator: Krulevitch, P.
System: The UNT Digital Library
Compact IR laser for calibration of space based sensors (open access)

Compact IR laser for calibration of space based sensors

An Er:YAG laser, operating at 2.94 microns, has been developed for in-theater calibration of space based infrared sensors. The laser is used to illuminate a spaceborne sensor focal plane from a surveyed ground reference point. The known reference point is compared to the laser position reported by the sensor, and boresight corrections are made. The Er:YAG laser is side pumped by a InGaAs diode array and is tuned to an atmospheric microwindow with and intracavity etalon. This technology is being directly applied to meet Army requirements for enhanced deep strike targeting information supplied to theater weapons systems.
Date: April 17, 1996
Creator: Kietrick, K. M.; Dezenberg, G.; Hamilton, C.; Vann, J. & LaSala, J.
System: The UNT Digital Library
A low power, tight seal, polyimide electrostatic microvalve (open access)

A low power, tight seal, polyimide electrostatic microvalve

An electrostatically-actuated polyimide microvalve is developed with sub-micron gaps between the electrodes to provide high force with low power consumption (< 1 mW). Built-in residual stress results in a curled bimorph cantilever which allows for a n-Licroactuator with large displacement. This microactuator is used to open and close a fluid path hole etched in silicon for a microvalve. The microactuator can be actuated with 25V for a displacement of 200 {mu}m. The cantilever actuator is mainly composed of polyimide, which is flexible enough to conform over the flow hole, thereby eliminating the need for the design of a valve seat.
Date: April 17, 1996
Creator: Lee, A.P.; Hamilton, J. & Trevino, J.
System: The UNT Digital Library
Status of ParaDyn: DYNA3D for parallel computing (open access)

Status of ParaDyn: DYNA3D for parallel computing

The evolution of DYNA3D from a vector supercomputer code into a parallel code is reviewed. Current status and target applications, especially those of interest to the Department of Defense.
Date: April 17, 1996
Creator: Goudreau, G. L.; Hoover, C. G.; DeGrout, A. J. & Raboin, P. J.
System: The UNT Digital Library
Building a programmable interface for physics codes using numeric python (open access)

Building a programmable interface for physics codes using numeric python

With its portability, ease to add built-in functions and objects in C, and fast array facility among many other features, Python proved to be an excellent language for creating programmable scientific applications. In addition to the two modules presented, there are also other progresses at LLNL in using Python. For example, Python interfaces are being developed for at least three graphics packages, and Python interpreter and applications have been built on distributed platforms such as meiko and Cray T3D.
Date: April 16, 1996
Creator: Yang, T.-Y.B.; Dubois, P.F. & Motteler, Z.C.
System: The UNT Digital Library
The Wahluke (North) Slope of the Hanford Site: History and present challenges (open access)

The Wahluke (North) Slope of the Hanford Site: History and present challenges

The Hanford Site was founded in early 1943 for the top secret government mission of producing plutonium for the world`s first atomic weapons. A great deal of land was needed, both to separate various Site facilities from each other, and to provide buffer zones for safety and security purposes. In total, 640 square miles were occupied by the original Hanford Site and its buffer zones. Much of this land had been earmarked for inclusion in the Columbia Basin Irrigation Project (CBP). After World War II ended, a series of national decisions led to a long-term mission for the Hanford Site, and area residents learned that the Site lands they had hoped to farm would be withheld from agricultural production for the foreseeable future. A long set of negotiations commenced between the federal management agency responsible for Hanford (the Atomic Energy Commission -- AEC), and the Bureau of Reclamation (BOR), Department of the Interior that managed the CBP. Some lands were turned back to agriculture, and other compromises made, in the Site`s far northern buffer lands known as the Wahluke Slope, during the 1950s. In the mid-1960s, further negotiations were about to allow farming on lands just north of the Columbia …
Date: April 16, 1996
Creator: Gerber, M.S.
System: The UNT Digital Library
The Annenberg Foundation A National Arts Education Consortium Getty Center for Education In The Arts (open access)

The Annenberg Foundation A National Arts Education Consortium Getty Center for Education In The Arts

Press information, on the Annenberg Foundation, announcing their latest series of grants towards arts education. A $4.3 million challenge grant to six regional institutes to show how the arts can boost student academic achievements. The foundation is working with the Getty Center for Education and their consortia which includes, North Texas Institute for Educators on the Visual Arts.
Date: April 15, 1996
Creator: unknown
System: The UNT Digital Library
Annenberg Foundation awards $1.43 million school reform grant to UNT arts consortium (open access)

Annenberg Foundation awards $1.43 million school reform grant to UNT arts consortium

A news release report, on North Texas Institute for Educators on the Visual Arts, one of the six recipients nationally of a $4.3 million challenge grant announced by the Annenberg Foundation. The grant goal is to reform public schools using a bold program of arts education. The grant will provide $1.43 million for UNT"s North Texas Institute for Educators on the Visual Arts to demonstrate how education in the arts can improve students.
Date: April 15, 1996
Creator: LeMay, Nancy
System: The UNT Digital Library