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Space-time methods for hyperbolic conservation laws

Description: Two challenges for computational fluid dynamics are problems that involve wave propagation over long times and problems with a wide range of amplitude scales. An example with both of these characteristics is the propagation and generation of acoustic waves, where the mean-flow amplitude scales are typically orders-of-magnitude larger than those of the generated acoustics. Other examples include vortex evolution and the direct simulation of turbulence. All these problems require greater than sec… more
Date: December 31, 1996
Creator: Lowrie, Robert B.; Roe, Philip L. & Leer, Bram Van
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Broadband acoustic source processing in a noisy shallow ocean environment

Description: Acoustic sources found in the ocean environment are spatially complex and broadband, complicating the analysis of received acoustic data considerably. A model-based approach is developed for a broadband source in a shallow ocean environment characterized by a normal-mode propagation model. Here we develop the optimal Bayesian solution to the broadband pressure-field enhancement and modal function extraction problem.
Date: July 18, 1996
Creator: Candy, J. V. & Sullivan, E. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Acoustically enhanced remediation, Phase 2: Technology scaling

Description: Weiss Associates is conducting the following three phase program investigating the in-situ application of acoustically enhanced remediation (AER) of contaminated unconsolidated soil and ground water under both saturated and unsaturated conditions: Phase I-- laboratory scale parametric investigation; Phase II--technology Scaling; and Phase III--large scale field tests. AER addresses the need for NAPL (either lighter or denser than water: LNAPL or DNAPL, respectively) in high and low permeability… more
Date: December 31, 1996
Creator: Iovenitti, J. L.; Hill, D. G.; Rynne, T. M.; Spadaro, J. F.; Hutchinson, W. & Illangasakere, T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Model-based processing for shallow ocean environments: The broadband problem

Description: Most acoustic sources found is the ocean environmental are spatially complex and broadband. When propagating in a shallow ocean these source characteristics complicate the analysis of received acoustic data considerably. The enhancement of broadband acoustic pressure- field measurements using a vertical array is discussed. Here a model- based approach is developed for a broadband source using a normal- mode propagation model.
Date: January 31, 1996
Creator: Candy, J. V. & Sullivan, E. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Dispersive wave processing: a model-based solution

Description: Wave propagation through various media represents a significant problem in many applications in acoustics and electromagnetics especially when the medium is dispersive. We post a general dispersive wave propagation model that could easily represent many classes of dispersive waves and proceed to develop a model-based processor employing this underlying structure. The general solution to the model-based dispersive wave estimation problem is developed using the Bayesian maximum a posteriori appro… more
Date: October 1, 1996
Creator: Candy, J.V. & Chambers, D.C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

An articulatorily constrained, maximum entropy approach to speech recognition and speech coding

Description: Hidden Markov models (HMM`s) are among the most popular tools for performing computer speech recognition. One of the primary reasons that HMM`s typically outperform other speech recognition techniques is that the parameters used for recognition are determined by the data, not by preconceived notions of what the parameters should be. This makes HMM`s better able to deal with intra- and inter-speaker variability despite the limited knowledge of how speech signals vary and despite the often limite… more
Date: December 31, 1996
Creator: Hogden, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Self-assembled thin film chemical sensors

Description: This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Current chemical sensors suffer from poor molecular specificity, sensitivity, and stability and seldom have the recovery properties needed for real-time monitoring applications. We have employed self-assembly techniques to covalently bond species- selective reagents directly to the surface of the transducer so that analyte/reagent chemistry occurs at … more
Date: November 1, 1996
Creator: Swanson, B. & Li, DeQuan
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Thermoacoustic engines and refrigerators

Description: This report is a transcript of a practice lecture given in preparation for a review lecture on the operation of thermoacoustic engines and refrigerators. The author begins by a brief review of the thermodynamic principles underlying the operation of thermoacoustic engines and refrigerators. Remember from thermodynamics class that there are two kinds of heat engines, the heat engine or the prime mover which produces work from heat, and the refrigerator or heat pump that uses work to pump heat. T… more
Date: December 31, 1996
Creator: Swift, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Third-order elastic solution of the stress field around a wellbore

Description: Within a certain range of strain, consolidated granular materials may be characterized as nonlinear elastic solids. The nonlinearity can be easily observed by examining the effect of stress on the acoustical properties of the material. Ignoring damage evolution and failure that occur in higher strains and the hysteretic behavior due to intercyranular friction, the material can be modeled as a nonlinear hyperelastic solid. A simple example of such a model is formulating the strain energy as a th… more
Date: April 1, 1996
Creator: Elata, D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Thermoacoustic natural gas liquefier

Description: This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project sought to develop a natural-gas-powered natural-gas liquefier that has absolutely no moving parts and requires no electrical power. It should have high efficiency, remarkable reliability, and low cost. The thermoacoustic natural-gas liquefier (TANGL) is based on our recent invention of the first no-moving-parts cryogenic refrigerator. In … more
Date: July 1, 1996
Creator: Swift, G.; Gardner, D.; Hayden, M.; Radebaugh, R. & Wollan, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Structural evolution in carbon aerogels as a function of precursor material and pyrolysis temperature

Description: Several organic reactions that proceed through a sol-gel transition have been identified at LLNL. The most-studied reaction involves the aqueous polycondensation of resorcinol (1,3-dihydroxybenzene) with formaldehyde. Recently, we have shown that phenol can be added to this polymerization as a comonomer. The resultant crosslinked gels are supercritically dried from carbon dioxide ({Tc}=31{degrees}C, P{sub c}=7.4 MPa) to give resorcinol-phenol-formaldehyde (RPF) aerogels. Because RPF aerogels ar… more
Date: April 1, 1996
Creator: Gross, J.; Alviso, C. T.; Neilsen, J. K. & Pekala, R. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Prototype acoustic resonance spectroscopy monitor

Description: This report reports on work performed for the International Atomic Energy Agency (IAEA) through the Program Office for Technical Assistance (POTAS). In this work, we investigate possible applications of nondestructive acoustics measurements to facilitate IAEA safeguards at bulk processing facilities. Two different acoustic techniques for verifying the internal structure of a processing tank were investigated. During this effort we also examined two acoustic techniques for assessing the fill lev… more
Date: March 1996
Creator: Sinha, D. N. & Olinger, C. T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A survey of models for the prediction of ambient ocean noise: Circa 1995

Description: The state of the art of model development for application to computer studies of undersea search systems utilizing acoustics is surveyed in this document. Due to the demands for surveillance of submarines operating in ocean basins, the development of noise models for application in deep oceans is fairly advanced and somewhat generic. This is due to the deep sound channel, discovered during World War II, which when present allows for long-range sound propagation with little or no interaction wit… more
Date: January 1996
Creator: Doolittle, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Application of chaotic time series for the characterization and control of fluidization and combustion systems. CRADA final report for CRADA No. ORNL92-0127

Description: Oak Ridge National Laboratory and Babcock and Wilcox, a prominent U.S. boiler manufacturer, have collaborated under this CRADA to investigate the application of deterministic chaos theory to improve the performance of fossil fuel boilers. The types of boilers investigated were coal-fired fluidized beds and more conventional pulverized coal systems. The results of this investigation demonstrate that chaotic time series analysis of boiler signals (e.g., pressure, acoustic and/or optical signals) … more
Date: February 1, 1996
Creator: Daw, C.S.; Fuller, T.A. & Flynn, T.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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