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Active voltammetric microsensors with neural signal processing. (open access)

Active voltammetric microsensors with neural signal processing.

Many industrial and environmental processes, including bioremediation, would benefit from the feedback and control information provided by a local multi-analyte chemical sensor. For most processes, such a sensor would need to be rugged enough to be placed in situ for long-term remote monitoring, and inexpensive enough to be fielded in useful numbers. The multi-analyte capability is difficult to obtain from common passive sensors, but can be provided by an active device that produces a spectrum-type response. Such new active gas microsensor technology has been developed at Argonne National Laboratory. The technology couples an electrocatalytic ceramic-metallic (cermet) microsensor with a voltammetric measurement technique and advanced neural signal processing. It has been demonstrated to be flexible, rugged, and very economical to produce and deploy. Both narrow interest detectors and wide spectrum instruments have been developed around this technology. Much of this technology's strength lies in the active measurement technique employed. The technique involves applying voltammetry to a miniature electrocatalytic cell to produce unique chemical ''signatures'' from the analytes. These signatures are processed with neural pattern recognition algorithms to identify and quantify the components in the analyte. The neural signal processing allows for innovative sampling and analysis strategies to be employed with the …
Date: December 11, 1998
Creator: Vogt, M. C.
System: The UNT Digital Library
Aerogel derived catalysts (open access)

Aerogel derived catalysts

Aerogels area class of colloidal materials which have high surface areas and abundant mesoporous structure. SiO{sub 2} aerogels show unique physical, optical and structural properties. When catalytic metals are incorporated in the aerogel framework, the potential exists for new and very effective catalysts for industrial processes. Three applications of these metal-containing SiO{sub 2} aerogels as catalysts are briefly reviewed in this paper--NO{sub x} reduction, volatile organic compound destruction, and partial oxidation of methane.
Date: December 11, 1996
Creator: Reynolds, J. G., LLNL
System: The UNT Digital Library
An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs (open access)

An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs

The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed.
Date: December 11, 2006
Creator: Huang, Z.
System: The UNT Digital Library
Application of the Balanced Hybrid Mode in Overmoded Corrugated Waveguides to Short Wavelength Dynamic Undulators (open access)

Application of the Balanced Hybrid Mode in Overmoded Corrugated Waveguides to Short Wavelength Dynamic Undulators

This report talks about Application of the Balanced Hybrid Mode in Overmoded Corrugated Waveguides to Short Wavelength Dynamic Undulators
Date: December 11, 2012
Creator: Bowden, G.B.; Chang, C.; Neilson, J.; Shumail, M.; SLAC; Tantawi, S.G. et al.
System: The UNT Digital Library
Beauty, charm and hyperon production at fixed-target experiments (open access)

Beauty, charm and hyperon production at fixed-target experiments

Over the years fixed-target experiments have performed numerous studies of particle production in strong interactions. The experiments have been performed with different types of beam particles of varying energies, and many different target materials. Since the physics of particle production is still not understood, ongoing research of phenomena that we observe as beauty, charm and strange-particle production is crucial if we are to gain an understanding of these fundamental processes. It is in this context that recent results from fixed-target experiments on beauty, charm, and hyperon production will be reviewed.
Date: December 11, 2002
Creator: Gottschalk, Erik
System: The UNT Digital Library
Best linear decoding of random mask images (open access)

Best linear decoding of random mask images

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Date: December 11, 1974
Creator: Woods, J.W.; Ekstrom, M.P.; Palmieri, T.M. & Twogood, R.E.
System: The UNT Digital Library
Comparative Experimental Study of X-Ray Absorption Spectroscopy and Electron Energy Loss Spectroscopy on Passivated U Surfaces (open access)

Comparative Experimental Study of X-Ray Absorption Spectroscopy and Electron Energy Loss Spectroscopy on Passivated U Surfaces

X-ray absorption spectroscopy and electron energy loss spectroscopy are complementary analytical techniques on energy and spatial resolution. These techniques are based on the same fundamental physical process of core excitation with either an incident photon or incident electron. In the proper experimental configuration the electron and photon inelastic scattering amplitudes are comparable and thus the x-ray and electron absorption edges look identical. We have applied these two complementary analytical techniques to investigate the electronic structure of C ion implanted U. Implantation of C{sup +} ions into U{sup 238} has been shown to produce a physically and chemically modified surface layer that passivates the surface preventing further air oxidation and corrosion. Comparison of the resultant spectra reveal that transitions between the initial state and a series of final states yield numerous strong features at the absorption edge that can provide structural information and information on the local chemical environment, including the character of the U 5f state.
Date: December 11, 2006
Creator: Nelson, A.; Moberlychan, W.; Bliss, R. A.; Siekhaus, W.; Felter, T. & Denliner, J.
System: The UNT Digital Library
Cost effectiveness of silent discharge plasma for point-of-use VOC emissions control in semiconductor fabrication (open access)

Cost effectiveness of silent discharge plasma for point-of-use VOC emissions control in semiconductor fabrication

Extensive research into the treatment and control of Volatile Organic Compounds (VOCs) from semiconductor industry manufacturing processes has identified the need for alternatives to existing combustion devices. Specifically, semiconductor manufacturing design is moving toward the application of effective, small-scale, abatement control technologies for specific point-of-use (POU) waste streams associated with a particular component or manufacturing tool. The consortium of companies involved in semiconductor precompetitive research and development known collectively as SEMATECH recently evaluated eleven emerging environmental technologies designed to treat POU process emissions of VOCs specific to the semiconductor industry. After rigorous technical review only one technology, the Silent Discharge Plasma (SDP) developed at Low Alamos National Laboratory, was considered to successfully meet the required technical performance standards and potential cost effectiveness necessary for continued consideration by SEMATECH in their point-of-use emissions control plans.
Date: December 11, 1996
Creator: Cummings, M. & Booth, S.R.
System: The UNT Digital Library
Current directions in screening-level ecological risk assessments (open access)

Current directions in screening-level ecological risk assessments

Ecological risk assessment (ERA) is a tool used by many regulatory agencies to evaluate the impact to ecological receptors from changes in environmental conditions. Widespread use of ERAs began with the United States Environmental Protection Agency's Superfund program to assess the ecological impact from hazardous chemicals released to the environment. Many state hazardous chemical regulatory agencies have adopted the use of ERAs, and several state regulatory agencies are evaluating the use of ERAs to assess ecological impacts from releases of petroleum and gas-related products. Typical ERAs are toxicologically-based, use conservative assumptions with respect to ecological receptor exposure duration and frequency, often require complex modeling of transport and exposure and are very labor intensive. In an effort to streamline the ERA process, efforts are currently underway to develop default soil screening levels, to identify ecological screening criteria for excluding sites from formal risk assessment, and to create risk-based corrective action worksheets. This should help reduce the time spent on ERAs, at least for some sites. Work is also underway to incorporate bioavailability and spatial considerations into ERAs. By evaluating the spatial nature of contaminant releases with respect to the spatial context of the ecosystem under consideration, more realistic ERAs with respect …
Date: December 11, 2000
Creator: Carlsen, T M & Efroymson, R A
System: The UNT Digital Library
Determination of Primordial Metallicity and Mixing in the Type IIP Supernova 1993W (open access)

Determination of Primordial Metallicity and Mixing in the Type IIP Supernova 1993W

We present the results of a large grid of synthetic spectra and compare them to early spectroscopic observations of SN 1993W. This supernova was discovered close to its explosion date and at a recession velocity of 5400 km/s is located in the Hubble flow. We focus here on two early spectra that were obtained approximately 5 and 9 days after explosion. We parameterize the outer supernova envelope as a power-law density profile in homologous expansion. In order to extract information on the value of the parameters a large number of models was required. We show that very early spectra combined with detailed models can provide constraints on the value of the power law index, the ratio of hydrogen to helium in the surface of the progenitor, the progenitor metallicity and the amount of radioactive nickel mixed into the outer envelope of the supernova. The spectral fits reproduce the observed spectra exceedingly well. The spectral results combined with the early photometry predict that the explosion date was 4.7 {+-} 0.7 days before the first spectrum was obtained. The ability to obtain the metallicity from early spectra make SN IIP attractive probes of chemical evolution in the universe and by showing that …
Date: December 11, 2002
Creator: Baron, E.; Nugent, Peter E.; Branch, David; Hauschildt, Peter H.; Turatto, M. & Cappellaro, E.
System: The UNT Digital Library
Determining Transition State Geometries in Liquids Using 2D-IR (open access)

Determining Transition State Geometries in Liquids Using 2D-IR

Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.
Date: December 11, 2007
Creator: Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P. & Harris, Charles B.
System: The UNT Digital Library
Development of a low-cost extruded scintillator with co-extruded reflector for the MINOS experiment (open access)

Development of a low-cost extruded scintillator with co-extruded reflector for the MINOS experiment

The MINOS experiment is a long-baseline, neutrino-oscillation experiment. In total, 28,000 m{sup 2} of scintillator is needed for the experiment. This is almost 300 tons of finished scintillator. The solution has been the development of an extruded scintillator with a 2-mm deep grove in the upper surface for a wavelength-shifting fiber and a co-extruded TiO{sub 2} coating as a reflector. The TiO{sub 2} coating also allows the scintillator to be directly epoxied into panels. Production and quality control techniques are presented.
Date: December 11, 2000
Creator: al., David F. Anderson et
System: The UNT Digital Library
The Development of the Undulator Controls Module at the Linac Coherent Light Source (open access)

The Development of the Undulator Controls Module at the Linac Coherent Light Source

The Linac Coherent Light Source, LCLS, at the SLAC National Accelerator Laboratory, SNAL, is the first hard x-ray Free Electron Laser. The Undulator Controls Module, UCM, controls five cams and two translation stages that regulate the position of each of the 33 permanent undulator magnet segments within 10 microns. The UCM package, hardware and software, was designed and built by the Advanced Photon Source at Argonne. Important lessons were learned throughout the collaborative design, installation, testing, and commissioning periods that could be invaluable to future similar controls projects.
Date: December 11, 2009
Creator: Alarcon, A. D.
System: The UNT Digital Library
Differences in Bulk Damage Probability Distributions Between Tripler and Z-Cuts of KDP and DKDP at 355 nm (open access)

Differences in Bulk Damage Probability Distributions Between Tripler and Z-Cuts of KDP and DKDP at 355 nm

Over the course of testing a substantial number of KDP and DKDP crystals from rapid and conventional growth processes, we have discovered that there is a consistent difference in the value of the damage resistance between z-cut and tripler, x-cut and y-cut crystals for a given test fluence. This increase in damage probability for tripler, x and y-cut crystals is consistent for both conventional and rapid growth KDP as well as DKDP. It also holds for unconditioned (S/1) and conditioned (R/l) tests and has values of 2.1 {+-} 0.6 and 1.5 {+-} 0.3 respectively. Testing has also revealed that there is no sensitivity to incident laser polarization. This is in direct contradiction to models based on simple, non-spherical absorbers. This result plus new information on the size and evolution of bulk damage density (see Runkel et al., this proceedings) has led to a reinterpretation of the growth parameter data for rapid growth NIF boules. It now appears that variations in impurity concentration throughout the boule do not affect the damage probability curve as dramatically as previously thought; although, this is still a topic of intensive investigation.
Date: December 11, 2000
Creator: Runkel, M & Burnham, A K
System: The UNT Digital Library
Diffraction theory in QCD and beyond (open access)

Diffraction theory in QCD and beyond

A study of the Pomeron in QCD is briefly outlined. Implications for the production of W/sup +/W/sup -/ and Z/sup 0/Z/sup 0/ pairs are described and the possibility that the electroweak scale is a major strong-interaction threshold discussed. The application of Pomeron phase-transition theory to SU(5) dynamical symmetry breaking is suggested and the related ''strong-interaction'' properties of the photon briefly mentioned.
Date: December 11, 1987
Creator: White, A.R.
System: The UNT Digital Library
Dipole aperture and superconductor requirements (open access)

Dipole aperture and superconductor requirements

The cost of an accelerator is not proportional to the aperture. A change in aperture by a certain percentage results in an overall accelerator cost change by only a fraction of that percentage; the fraction may be between 0.1 and 0.5 and is almost independent of the bending field. This estimate is obtained by analyzing the superconductor requirements as a function of aperture and by making rough estimates of the largest cost items of the accelerator such as magnets and ring tunnel.
Date: December 11, 1983
Creator: Wipf, S.L.
System: The UNT Digital Library
Dissecting the Gravitational Lens B1608 656. II. Precision Measurements of the Hubble Constant, Spatial Curvature, and the Dark Energy Equation of State (open access)

Dissecting the Gravitational Lens B1608 656. II. Precision Measurements of the Hubble Constant, Spatial Curvature, and the Dark Energy Equation of State

Strong gravitational lens systems with measured time delays between the multiple images provide a method for measuring the 'time-delay distance' to the lens, and thus the Hubble constant. We present a Bayesian analysis of the strong gravitational lens system B1608+656, incorporating (1) new, deep Hubble Space Telescope (HST) observations, (2) a new velocity dispersion measurement of 260 {+-} 15 km s{sup -1} for the primary lens galaxy, and (3) an updated study of the lens environment. Our analysis of the HST images takes into account the extended source surface brightness, and the dust extinction and optical emission by the interacting lens galaxies. When modeling the stellar dynamics of the primary lens galaxy, the lensing effect, and the environment of the lens, we explicitly include the total mass distribution profile logarithmic slope {gamma}{prime} and the external convergence {kappa}{sub ext}; we marginalize over these parameters, assigning well-motivated priors for them, and so turn the major systematic errors into statistical ones. The HST images provide one such prior, constraining the lens mass density profile logarithmic slope to be {gamma}{prime} = 2.08 {+-} 0.03; a combination of numerical simulations and photometric observations of the B1608+656 field provides an estimate of the prior for {kappa}{sub …
Date: December 11, 2009
Creator: Suyu, S. H.; Marshall, P. J.; Auger, M. W.; Hilbert, S.; Blandford, R. D.; Koopmans, L. V. E. et al.
System: The UNT Digital Library
Dynamic Imaging of Surface Motion with a Stereo Borescope (open access)

Dynamic Imaging of Surface Motion with a Stereo Borescope

A new stereo borescope has been investigated that would provide a time-resolved calibrated method of recording the motion and deformation of a three-dimensional (3-D) surface during explosively driven dynamic shock experiments at the Nevada Test Site. In these experiments, geometries would likely prove to be incompatible with conventional direct optical systems. Single line-of-sight borescopes lack adequate depth-of-field for quantitative imaging of the 3-D surface. To improve depth-of-field and provide time resolution, a stereo borescope has been fabricated for use with a nine-frame framing camera. At one end, stereo optics couple light from the dynamic surface into a pair of flexible 1-mm-diameter correlated fiber-optic bundles. At the other end, small-format lenses (~3 mm) interface with the framing camera, which is set up to simultaneously record the separate-perspective views. All nine frames could be recorded in a period as short as 1.8 μs, and spatial resolution is optimized to 11 line-pairs per mm. To achieve pseudo 3-D depth perception, photogrammetric analysis has been demonstrated with commercial software from ADAM technology (Australia). This paper presents the results from time-resolved stereo images of dynamic surfaces collected in a series of high-explosives experiments at the National Security Technologies, LLC, “Boom Box” in Santa Barbara, CA. …
Date: December 11, 2008
Creator: Berninger, Michael & Baker, Stuart
System: The UNT Digital Library
Effect of Thermal Annealing and Second Harmonic Generation on Bulk Damage Performance of Rapid-Growth KDP Type I Doublers at 1064 nm (open access)

Effect of Thermal Annealing and Second Harmonic Generation on Bulk Damage Performance of Rapid-Growth KDP Type I Doublers at 1064 nm

This paper discusses the results of thermal annealing and in-situ second harmonic generation (SHG) damage tests performed on six rapid growth KDP type 1 doubler crystals at 1064 nm (1 {omega}) on the Zeus automated damage test facility. Unconditioned (S/1) and conditioned (R/1) damage probability tests were performed before and after thermal annealing, then with and without SHG on six doubler crystals from the NIF-size, rapid growth KDP boule F6. The tests revealed that unannealed, last-grown material from the boule in either prismatic or pyramidal sectors exhibited the highest damage curves. After thermal annealing at 160 C for seven days, the prismatic sector samples increased in performance ranging from 1.6 to 2.4X, while material from the pyramidal sector increased only modestly, ranging from 1.0 to 1.4X. Second harmonic generation decreased the damage fluence by an average of 20 percent for the S/1 tests and 40 percent for R/1 tests. Conversion efficiencies under test conditions were measured to be 20 to 30 percent and compared quite well to predicted behavior, as modeled by LLNL frequency conversion computer codes. The damage probabilities at the 1 {omega} NIF redline fluence (scaled to 10 ns via t{sup 0.5}) for S/1 tests for the unannealed …
Date: December 11, 2000
Creator: Runkel, M.; Maricle, S.; Torres, R.; Auerbach, J.; Floyd, R.; Hawley-Fedder, R. et al.
System: The UNT Digital Library
Electron cloud instabilities in the Proton Storage Ring andSpallation Neutron Source (open access)

Electron cloud instabilities in the Proton Storage Ring andSpallation Neutron Source

Electron cloud instabilities in the Los Alamos ProtonStorage Ring (PSR) and those foreseen forthe Oak Ridge SpallationNeutron Source (SNS) are examined theoretically, numerically, andexperimentally.
Date: December 11, 2002
Creator: Blaskiewicz, M.; Furman, M. A.; Pivi, M. & Macek, R. J.
System: The UNT Digital Library
Electronic Durability of Flexible Transparent Films from Type-Specific Single-Wall Carbon Nanotubes (open access)

Electronic Durability of Flexible Transparent Films from Type-Specific Single-Wall Carbon Nanotubes

The coupling between mechanical flexibility and electronic performance is evaluated for thin films of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) deposited on compliant supports. Percolated networks of type-purified SWCNTs are assembled as thin conducting coatings on elastic polymer substrates, and the sheet resistance is measured as a function of compression and cyclic strain through impedance spectroscopy. The wrinkling topography, microstructure and transparency of the films are independently characterized using optical microscopy, electron microscopy, and optical absorption spectroscopy. Thin films made from metallic SWCNTs show better durability as flexible transparent conductive coatings, which we attribute to a combination of superior mechanical performance and higher interfacial conductivity.
Date: December 11, 2011
Creator: Harris, J.; Iyer, S.; Bernhardt, A.; Huh, J. Y.; Hudson, S.; Fagan, J. et al.
System: The UNT Digital Library
Electronically Nonadiabatic Dynamics via Semiclassical Initial Value Methods (open access)

Electronically Nonadiabatic Dynamics via Semiclassical Initial Value Methods

In the late 1970's Meyer and Miller (MM) [J. Chem. Phys. 70, 3214 (1979)] presented a classical Hamiltonian corresponding to a finite set of electronic states of a molecular system (i.e., the various potential energy surfaces and their couplings), so that classical trajectory simulations could be carried out treating the nuclear and electronic degrees of freedom (DOF) in an equivalent dynamical framework (i.e., by classical mechanics), thereby describing non-adiabatic dynamics in a more unified manner. Much later Stock and Thoss (ST) [Phys. Rev. Lett. 78, 578 (1997)] showed that the MM model is actually not a 'model', but rather a 'representation' of the nuclear-electronic system; i.e., were the MMST nuclear-electronic Hamiltonian taken as a Hamiltonian operator and used in the Schroedinger equation, the exact (quantum) nuclear-electronic dynamics would be obtained. In recent years various initial value representations (IVRs) of semiclassical (SC) theory have been used with the MMST Hamiltonian to describe electronically non-adiabatic processes. Of special interest is the fact that though the classical trajectories generated by the MMST Hamiltonian (and which are the 'input' for an SC-IVR treatment) are 'Ehrenfest trajectories', when they are used within the SC-IVR framework the nuclear motion emerges from regions of non-adiabaticity on one …
Date: December 11, 2008
Creator: Miller, William H.
System: The UNT Digital Library
Estimating the consequences of significant fracture flow at Yucca Mountain (open access)

Estimating the consequences of significant fracture flow at Yucca Mountain

A simple model is proposed for investigating the possibility of significant fracture flow at Yucca Mountain, Nevada. The model allows an estimate of the number of flowing fractures at Yucca Mountain based on the size of the fractures and the yearly volume of infiltrating water. Given the number of flowing fractures, the number of waste containers they contact is estimated by a geometric argument. Preliminary results indicate that the larger the flowing fractures, the lower the releases of radionuclides. Also, even with significant fracture flow, releases could be well below the limits set by the Environmental Protection Agency.
Date: December 11, 1991
Creator: Gauthier, J. H.; Wilson, M. L. & Lauffer, F. C.
System: The UNT Digital Library
The Evolution of Publishing Agreements at the University of Michigan (open access)

The Evolution of Publishing Agreements at the University of Michigan

Article on the evolution of publishing agreements at the University of Michigan Library. Taking as an example an open-access journal with a single editor, this article discusses the various configurations of rights agreements used by the University of Michigan Library throughout the evolution of its publishing operation, the advantages of the various models, and the reasons for moving from one to another.
Date: December 11, 2014
Creator: Hawkins, Kevin S.
System: The UNT Digital Library