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Effect of Intense Sound Waves on a Stationary Gas Flame

Description: Intense sound waves with a resonant frequency of 5000 cycles per second were imposed on a stationary propane-air flame issuing from a nozzle. In addition to a slight increase of the flame velocity, a fundamental change both in the shape of the burning zone and in the flow pattern could be observed. An attempt is made to explain the origin of the variations in the flame configuration on the basis of transition at the nozzle from jet flow to potential flow.
Date: July 1950
Creator: Hahnemann, H. & Ehret, L.
Partner: UNT Libraries Government Documents Department

Propagation of Sound Into a Wind-Created Shadow Zone

Description: Memorandum presenting a general wave equation derived governing the propagation of sound in a stratified moving medium, the velocity of which varies only along one coordinate. A simplified equation is adopted which is satisfactory for the present application.
Date: April 22, 1957
Creator: Pridmore-Brown, David C.
Partner: UNT Libraries Government Documents Department

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 approach which leads to the nonlinear extended Kalman filter processor.
Date: October 1, 1996
Creator: Candy, J.V. & Chambers, D.C.
Partner: UNT Libraries Government Documents Department

Implementation of an acoustic emission proximity detector for use in generating glass optics

Description: We are using the approach acoustic emission (AE) signal during a grinding operation to detect the proximity of the grinding wheel relative to a brittle material workpiece and are using this detection as a feed- back control signal in our CNC. The repeatability of the AE signal during the wheel approach is the key that allows AE to be used as a proximity detector and is demonstrated at LLNL to be about mm. We noted significant changes of the AE signal as process parameters are modified, but conclude that with a quick CNC calibration routine and holding the parameters constant during a given operation, the AE system can be successfully used to sense pre- contact wheel- to- workpiece separation. Additionally, the AE sensing system allows real- time monitoring during grinding to provide in- process information. The first prototype of an AE system on a commercially available generator is currently be tested at the Center for Optics Manufacturing.
Date: November 11, 1996
Creator: Blaedel, K. L.; Piscotty, M. A. & Taylor, J. S.
Partner: UNT Libraries Government Documents Department

Time-Resolved Studies of Laser Damage Processes in DKDP Crystals

Description: The authors have used a 3-color imaging technique to obtain time-resolved series of images during nanosecond laser damage in bulk DKDP crystals. In contrast to single-pump, single-probe time-resolved imaging techniques, they are able to correlate behavior during single damage events. This enables us to observe a range of morphological dynamics that is otherwise difficult to study, including: the propagation of elastic sound waves and the liquid/solid melt front from the damage nucleation site and the dynamics of crack formation and propagation.
Date: February 12, 2000
Creator: Jiang, H; McNary, R; Tom, H; Yan, M; Radousky, H & Demos, S
Partner: UNT Libraries Government Documents Department

Infrasonic observation of earthquakes

Description: Infrasound signals generated by earthquakes have been detected at arrays operated by the Los Alamos National Laboratory. Three modes of propagation are possible and all have been observed by the authors. The observations suggest that regions remote from the epicenters are excited and may serve as secondary source regions. A relation is found between the normalized peak amplitudes and the seismic magnitudes.
Date: December 31, 1998
Creator: Mutschlecner, J.P. & Whitaker, R.W.
Partner: UNT Libraries Government Documents Department

Speech coding

Description: Speech is the predominant means of communication between human beings and since the invention of the telephone by Alexander Graham Bell in 1876, speech services have remained to be the core service in almost all telecommunication systems. Original analog methods of telephony had the disadvantage of speech signal getting corrupted by noise, cross-talk and distortion Long haul transmissions which use repeaters to compensate for the loss in signal strength on transmission links also increase the associated noise and distortion. On the other hand digital transmission is relatively immune to noise, cross-talk and distortion primarily because of the capability to faithfully regenerate digital signal at each repeater purely based on a binary decision. Hence end-to-end performance of the digital link essentially becomes independent of the length and operating frequency bands of the link Hence from a transmission point of view digital transmission has been the preferred approach due to its higher immunity to noise. The need to carry digital speech became extremely important from a service provision point of view as well. Modem requirements have introduced the need for robust, flexible and secure services that can carry a multitude of signal types (such as voice, data and video) without a fundamental change in infrastructure. Such a requirement could not have been easily met without the advent of digital transmission systems, thereby requiring speech to be coded digitally. The term Speech Coding is often referred to techniques that represent or code speech signals either directly as a waveform or as a set of parameters by analyzing the speech signal. In either case, the codes are transmitted to the distant end where speech is reconstructed or synthesized using the received set of codes. A more generic term that is applicable to these techniques that is often interchangeably used with speech coding is the ...
Date: May 8, 1998
Creator: Ravishankar, C., Hughes Network Systems, Germantown, MD
Partner: UNT Libraries Government Documents Department

Development of a GaAs Monolithic Surface Acoustic Wave Integrated Circuit

Description: An oscillator technology using surface acoustic wave delay lines integrated with GaAs MESFET electronics has been developed for GaAs-based integrated microsensor applications. The oscillator consists of a two-port SAW delay line in a feedback loop with a four-stage GaAs MESFET amplifier. Oscillators with frequencies of 470, 350, and 200 MHz have been designed and fabricated. These oscillators are also promising for other RF applications.
Date: March 8, 1999
Creator: Baca, A.G.; Casalnuovo, S.C.; Drummond, T.J.; Frye, G.C.; Heller, E.J.; Hietala, V.M. et al.
Partner: UNT Libraries Government Documents Department

Low-jitter sonoluminescence cell

Description: This report constitutes the final report for subcontract B338667. The statement of work for this subcontract was divided into three tasks: Task 1: Produce and quantify the stability of a sonoluminescence cell. The quantification will entail measuring the variation of the amplitude of the light flashes, here called events, and the variation in the time between the individual events i.e., the jitter. On a best effort basis we desire the light amplitude to be stable within 20 So and the jitter between events should be less than 100 ps on average over a period of at least an hour. Task 2: The quantified cell, which provides the stability and jitter characteristics described above, must be arranged so that it has an optical quality viewing access. The optical properties will enable us to use laser measurement techniques to perform optical probing. Task 3: There will be a brief informal report on the production of the cell and how it was quantified. This report need only be sufficient to allow the reproduction of the cell at LLNL.
Date: January 1, 1998
Creator: Lee, R. W., LLNL
Partner: UNT Libraries Government Documents Department

Chemical class specificity using self-assembled monolayers on SAW devices

Description: We have studied the chemical selectivity and sensitivity of surface acoustic wave (SAW) sensors covered by (COO{sup {minus}}){sub 2}/Cu{sup 2+}-terminated interfaces by examining the response of self-assembled monolayer (SAM) films formed from the solution phase for 36, 84, and 180 h adsorption times. These organomercaptan SAMs were prepared on thin-film Au surfaces having variable, controlled grain size. The SAW response from the carboxylate coordinated Cu{sup 2+}-terminated SAM is compared to that from methyl-terminated SAM, as these films interact with a vapor-phase organophosphonate analyte and the vapors of common organic solvents. Results have implications for designing and reliably fabricating chemical sensors that respond to specific organic analytes.
Date: June 1, 1996
Creator: Thomas, R.C.; Ricco, A.J.; Yang, H.C.; Dermody, D. & Crooks, R.M.
Partner: UNT Libraries Government Documents Department

BBN technical memorandum W1291 infrasound model feasibility study

Description: The purpose of this study is to determine the need and level of effort required to add existing atmospheric databases and infrasound propagation models to the DOE`s Hydroacoustic Coverage Assessment Model (HydroCAM) [1,2]. The rationale for the study is that the performance of the infrasound monitoring network will be an important factor for both the International Monitoring System (IMS) and US national monitoring capability. Many of the technical issues affecting the design and performance of the infrasound network are directly related to the variability of the atmosphere and the corresponding uncertainties in infrasound propagation. It is clear that the study of these issues will be enhanced by the availability of software tools for easy manipulation and interfacing of various atmospheric databases and infrasound propagation models. In addition, since there are many similarities between propagation in the oceans and in the atmosphere, it is anticipated that much of the software infrastructure developed for hydroacoustic database manipulation and propagation modeling in HydroCAM will be directly extendible to an infrasound capability. The study approach was to talk to the acknowledged domain experts in the infrasound monitoring area to determine: 1. The major technical issues affecting infrasound monitoring network performance. 2. The need for an atmospheric database/infrasound propagation modeling capability similar to HydroCAM. 3. The state of existing infrasound propagation codes and atmospheric databases. 4. A recommended approach for developing the required capabilities. A list of the people who contributed information to this study is provided in Table 1. We also relied on our knowledge of oceanographic and meteorological data sources to determine the availability of atmospheric databases and the feasibility of incorporating this information into the existing HydroCAM geographic database software. This report presents a summary of the need for an integrated infrasound modeling capability in Section 2.0. Section 3.0 provides a recommended ...
Date: May 1, 1998
Creator: Farrell, T., BBN Systems and Technologies
Partner: UNT Libraries Government Documents Department

BBN technical memorandum W1310 hydroacoustic network capability studies

Description: This report summarizes work performed under contract to Lawrence Livermore National Laboratory during the period 1 August to 30 November 1997. Four separate tasks were undertaken during this period which investigated various aspects of hydroacoustic network performance using the Hydroacoustic Coverage Assessment Model (HydroCAM). The purpose of this report is to document each of these tasks.
Date: December 1, 1997
Creator: Angell, J., LLNL
Partner: UNT Libraries Government Documents Department

Nonlinear elastic wave interaction in a sandstone bar: A summary of recent pulse-mode experiments

Description: We have performed nonlinear pulse propagation experiments in a 3.8 cm diameter rod of Berea sandstone 1.8 m long at ambient conditions. Unlike earlier studies, we measured acceleration and not displacement. Moreover, we detected 2nd and 3rd harmonic growth at smaller strain amplitudes than were observed previously (10{sup {minus}7}). Harmonic growth at identical strain amplitudes has also been noted in resonance studies using the same rock type. Current measurements are underway with the rod in vacuum where the wave attenuation is less and the conditions can be carefully controlled. Ultimately, we wish to test the validity of current analytic and numerical models for nonlinear propagation in microcracked materials.
Date: March 1, 1995
Creator: Johnson, P.A.; TenCate, J.A.; Cherry, R.; McCall, K.; Van Den Abeele, K.; Kadish, A. et al.
Partner: UNT Libraries Government Documents Department

Single-monolayer in situ modulus measurements using a SAW device: Photocrosslinking of a diacetylenic thiol-based monolayer

Description: We report direct measurement of the modulus change that accompanies the crosslinking of a single molecular monolayer. We measured a change in elastic modulus of 5 x 10{sup 10} dyn/cm{sup 2} as a result of ultraviolet-induced photocrosslinking of a single surface-confined monolayer of the conjugated diacetylenic thiol HS(CH{sub 2}){sub 10}C{triple_bond}CC{triple_bond}C(CH{sub 2}){sub 10}COOH, designated {open_quotes}DAT{close_quotes} hereafter. The modulus measurement was made on a monolayer of DAT chemisorbed upon a gold film on the surface of a 97-MHz ST-quartz surface acoustic wave delay line. The ratio of the changes recorded in SAW velocity and attenuation, approximately 4:1, suggests that the measured effect is mainly a change in the elastic (real) component of the complex shear modulus, viscous changes playing a lesser role. In relation to typical polymer modulus values, the change of 5 x 10{sup 10} dyn/cm{sup 2} is consistent with a change from a rubbery material (G{prime} {approximately} 10{sup 7} - 10{sup 8} dyn/cm{sup 2}) to a fairly rigid, glassy material (G{prime} {approximately} 10{sup 10} dyn/cm{sup 2}), reasonable for comparison of the monolayer in its as-adsorbed and crosslinked forms. This report of the direct SAW-based measurement of the modulus change associated with the crosslinking of a single molecular monolayer is complementary to and consistent with previous in-situ measurements of this process using thickness-shear mode resonators.
Date: October 1, 1997
Creator: Ricco, A.J.; Staton, A.W.; Crooks, R.M. & Kim, Taisun
Partner: UNT Libraries Government Documents Department

Evaluation of a prototype infrasound system

Description: Under Department of Energy sponsorship, Sandia National Laboratories and Los Alamos National Laboratory cooperated to develop a prototype infrasonic array, with associated documentation, that could be used as part of the International Monitoring System. The United States Government or foreign countries could procure commercially available systems based on this prototype to fulfill their Comprehensive Test Ban Treaty (CTBT) obligations. The prototype is a four-element array in a triangular layout as recommended in CD/NTB/WP.224 with an element at each corner and one in the center. The prototype test configuration utilize an array spacing of 1 km. The prototype infrasound system has the following objectives: (1) Provide a prototype that reliably acquires and transmits near real-time infrasonic data to facilitate the rapid location and identification of atmospheric events. (2) Provide documentation that could be used by the United States and foreign countries to procure infrasound systems commercially to fulfill their CTBT responsibilities. Infrasonic monitoring is an effective, low cost technology for detecting atmospheric explosions. The low frequency components of explosion signals propagate to long ranges (few thousand kilometers) where they can be detected with an array of sensors. Los Alamos National Laboratory`s expertise in infrasound systems and phenomenology when combined with Sandia`s expertise in providing verification quality system for treaty monitoring make an excellent team to provide the prototype infrasound sensor system. By September 1997, the prototype infrasound system will have been procured, integrated, evaluated and documented. Final documentation will include a system requirements document, an evaluation report and a hardware design document. The hardware design document will describe the various hardware components used in the infrasound prototype and their interrelationships.
Date: August 1, 1997
Creator: Whitaker, R.; Sandoval, T.; Breding, D. & Kromer, D.
Partner: UNT Libraries Government Documents Department

Noninvasive Measurement of Acoustic Properties of Fluids Using Ultrasonic Interferometry Technique

Description: A swept-frequency ultrasonic interferometry technique is used for noninvasively determining acoustic properties of fluids inside containers. Measurements over a frequency range 1-15 MHz on six liquid chemicals are presented. Measurements were made with the liquid inside standard rectangular optical glass cells and stainless steel cylindrical shells. A theoretical model based on one-dimensional planar acoustic wave propagation through multi-layered media is employed for the interpretation of the observed resonance (interference) spectrum. Two analytical methods, derived from the transmission model are used for determination of sound speed, sound attenuation coefficient, and density of liquids from the relative amplitude and half-power peak width of the observed resonance peaks. Effects of the container material and geometrical properties, path-length, wall thickness are also studied. This study shows that the interferometry technique and the experimental method developed are capable of accurate determination of sound speed, sound attenuation, and density in fluids completely noninvasively. It is a capable and versatile fluid characterization technique and has many potential NDE applications.
Date: June 15, 1997
Creator: Han, W.; Sinha, D.N.; Springer, K.N. & Lizon, D.C.
Partner: UNT Libraries Government Documents Department


Description: Sensor Research and Development Corporation (SRD) has been contracted to develop and deliver a prototype instrument capable of the in situ detection and measurement of low levels of gaseous mercury for use in thermal waste treatment continuous emissions monitoring. The goal is to develop a fast, simple, inexpensive and reliable in situ sensor instrument for detecting and monitoring vaporized mercury that should be able to react to low (less than 5 mg/m 3 ) levels of mercury vapor, should be site deployable and provide continuous data on either cumulative mercury exposure or instantaneous concentration. Over the course of the reporting period, sensor responses were measured and analyzed for a wide range of sensing film thicknesses, operating temperatures, and adhesion layers. From this data, an optimal combination of those parameters was chosen. The film was then incorporated into the SAW sensing element, and rigorous testing has begun. To date, sensor responses to wide concentration ranges (0.7 ppb to 500 ppb) have been measured. Furthermore, a contract modification to include measurement of total mercury (both in elemental and reacted forms) has been requested and is expected to be finalized before the end of November, 1998. Finally, plans have been made for initial visits to the TSCA facility in Oak Ridge, TN and the University of North Dakota�s EERC facility to gather information required for the construction of the prototype instrument and to discuss possible future collaborations and field testing.
Date: September 2, 1998
Partner: UNT Libraries Government Documents Department

Synchronous picosecond sonoluminescence: Developing and characterizing a new light source. Final report, December 1991--December 1994

Description: Sonoluminescence is the remarkable physical process whereby sound energy is transduced into light by the motion of a trapped bubble of gas in a liquid. Interest in sonoluminescence (or SL as we like to call it) is based upon our insight that sound energy must focus by over twelve orders of magnitude to make light. Thus SL is Nature`s most nonlinear oscillator.
Date: September 1, 1997
Creator: Putterman, S.J.
Partner: UNT Libraries Government Documents Department

Analysis of the acoustic conversion efficiency for infrasound from atmospheric entry of NEO`s

Description: ReVelle (1995) has recently presented a summary of available infrasonic signals from near earth objects (NEO`s) that entered the earth`s atmosphere between 1960-1980. We will analyze these signals using a formalism developed by Cox (1958) to calculate the energy of explosive sources in the atmosphere. For each source we will calculate the acoustic conversion efficiency for each source, i.e., the fraction of the original source energy that is available to couple into an acoustic wave. Based on results in Cox with conventional explosions, this quantity is expected to depend weakly on the range from the source. Since this quantity is difficult to estimate using fundamental blast wave theories, we instead use well-known, and independently calibrated, semi-empirical source energy-wave period (at maximum amplitude) scaling relations developed in the 1960-1975 period by the U.S. Air Force to determine the source energy, E{sub s}, from observations. Using E{sub s} and range to the source along with various observed signal and atmospheric properties, the efficiency can be computed, similar calculations have been done for other relevant atmospheric phenomena for low altitude sources. For example, thunder observations at relatively close range have been used by Few and co-workers to determine an acoustic conversion efficiency of about 0.4%. The only previous estimation for meteors was made by Astapovich (1946) who determined the acoustic efficiency to be less than 0.01%. By computing this efficiency factor we hope to predict the expected detection rate of large NEO`s for the proposed CTBT global scale infrasonic array systems, and to establish the rate of false alarms due to natural atmospheric explosions.
Date: February 1, 1996
Creator: Whitaker, R.W. & ReVelle, D.O.
Partner: UNT Libraries Government Documents Department


Description: As part of our study on ''Relationships between seismic properties and rock microstructure'', we have studied (1) Effects of pore texture on porosity, permeability, and sonic velocity. We show how a relation can be found between porosity, permeability, and velocity by separating the formations of rocks with similar pore textures.
Date: June 30, 2003
Creator: Mavko, Gary
Partner: UNT Libraries Government Documents Department