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ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT

Description: The power point presentation for the Natural Gas Technologies II Conference held on February 8-11, 2004 in Phoenix AZ, published the presentations made at the conference, therefore required all presenters to submit their presentation prior to November 2003. However in the remainder of year, significant new test data became available which were incorporated in the actual presentation made at the Natural Gas Technologies II Conference. The 6th progress report presents the updated actual slide show used during the paper presentation by Richard Guiler.
Date: January 5, 2004
Creator: LOTH, John L.; MORRIS, GARY J.; PALMER, GEORGE M. & GUILER, RICHARD
Partner: UNT Libraries Government Documents Department

Feasibility of Large-Scale Ocean CO2 Sequestration

Description: The project accomplishments in 2005 have been exceptional, and have seen radical new techniques successfully devised and implemented. At the outset the goal set was to create a system dubbed FOCE--Free Ocean CO{sub 2} Enrichment--for investigating the impact of rapidly growing ocean CO{sub 2} levels from passive absorption by the surface ocean. A paper describing progress in this area is included with this report. On June 29, 2005 the P.I. presented a seminar on this work at NETL, and after discussion with Program Officers it was suggested that a return to the original project focus of investigating direct disposal techniques, rather than passive disposal effects, should be undertaken. This suggestion was rapidly acted upon, and in November 2005 a major field breakthrough was accomplished in collaboration with colleagues from NETL, MIT, and AIST (Japan). In this effort the real time three-dimensional acoustic detection of a freely released small-scale CO{sub 2} plume was accomplished. In addition we have successfully field tested the theoretical model of Zeebe and Wolf-Gladrow for CO{sub 2} system kinetics at depth, thus leading to more accurate prediction of the local pH perturbations of a CO{sub 2} plume.
Date: December 1, 2005
Creator: Brewer, Peter G. & Barry, James
Partner: UNT Libraries Government Documents Department

Measurement of sound speed vs. depth in South Pole ice: pressure waves and shear waves

Description: We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at {approx}5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background.
Date: June 4, 2009
Creator: Collaboration, IceCube & Klein, Spencer
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

Development of GaAs-Based Monolithic Surface Acoustic Wave Devices for Chemical Sensing and RF Filter Applications

Description: Since their invention in the mid-1960's, surface acoustic wave (SAW) devices have become popular for a wide variety of applications. SAW devices represent a low-cost and compact method of achieving a variety of electronic signal processing functions at high frequencies, such as RF filters for TV or mobile wireless communications [1]. SAW devices also provide a convenient platform in chemical sensing applications, achieving extremely high sensitivity to vapor phase analytes in part-per-billion concentrations [2]. Although the SAW acoustic mode can be created on virtually any crystalline substrate, the development of SAW technology has historically focused on the use of piezoelectric materials, such as various orientations of either quartz or lithium niobate, allowing the devices to be fabricated simply and inexpensively. However, the III-V compound semiconductors, and GaAs in particular, are also piezoelectric as a result of their partially covalent bonding and support the SAW acoustic mode, allowing for the convenient fabrication of SAW devices. In addition, GaAs microelectronics has, in the past decade, matured commercially in numerous RF wireless technologies. In fact, GaAs was recognized long ago as a potential candidate for the monolithic integration of SAW devices with microelectronics, to achieve compact RF signal processing functions [3]. The details of design and fabrication of SAW devices can be found in a variety of references [1].
Date: December 24, 1998
Creator: Baca, A.G.; Casalnuovo, S.A.; Drummond, T.J.; Frye, G.C.; Heller, E.J.; Hietala, V.M. et al.
Partner: UNT Libraries Government Documents Department

Predictions of acoustic signals from explosions above and below the ocean surface: source region calculations

Description: In support of the Comprehensive Test Ban, research is underway on the long range propagation of signals from nuclear explosions in the deep underwater sound (SOFAR) channel. This first phase of our work at LLNL on signals in the source regions considered explosions in or above the deep (5000 m) ocean. We studied the variation of wave properties and source region energy coupling as a function of height or depth of burst. Initial calculations on CALE, a two-dimensional hydrodynamics code developed at LLNL by Robert Tipton, were linked at a few hundred milliseconds to a version of NRL`s weak shock code, NPE, which solves the nonlinear progressive wave equation. The wave propagation simulation was performed down to 5000 m depth and out to 10,000 m range. We have developed a procedure to convert the acoustic signals at 10 km range into `starter fields` for calculations on a linear acoustics code which will extend the propagation to ocean basin distances. Recently we have completed calculations to evaluate environmental effects (shallow water, bottom interactions) on signal propagation. We compared results at 25 km range from three calculations of the same I kiloton burst (50 m height-of-burst) in three different environments, namely, deep water, shallow water, and a case with shallow water sloping to deep water. Several results from this last `sloping bottom` case will be 2016 discussed below. In this shallow water study, we found that propagation through shallow water complicates and attenuates the signal; the changes made to the signal may impact detection and discrimination for bursts in some locations.
Date: December 1, 1996
Creator: Clarke, D.B.; Piacsek, A. & White, J.W.
Partner: UNT Libraries Government Documents Department

Detection of blockages in process piping Los Alamos National Laboratory. Final report

Description: The attached reports and proposal summarize the work to date for the revised Ultrasonic Resonance Interferometry system. The most recent set of experiments, to determine the accuracy of the implementation of a new calibration curve to account for the variation of the wave speed with temperature, were never completed due to lack of funding. The general focus of the ongoing work, outlined in the weekly reports, had been improvements in accuracy of the measurement system using software modifications. The future focus of the project, as outlined in the attached proposal, was to incorporate a thermal conductivity probe with the ultrasonic measurement system to allow measurement of fluids which have a bimodal wavespeed vs. molarity relation.
Date: October 1, 1994
Creator: Histand, M.B.
Partner: UNT Libraries Government Documents Department

Cyclodextrin-based chemical microsensors for Volatile Organic Compounds (VOCs)

Description: This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This project addressed the development of surface-acoustic-wave (SAW)-based chemical sensors for remote, real-time sensing in air, groundwater, and possibly soil, of chlorinated and aromatic hydrocarbons using innovative molecular self-assembly techniques. Our goal is parts per billion (ppb) sensitivity to specific aromatic and chlorinated hydrocarbons using cyclodextrin as the selective layer of a SAW-based mass sensor. We have demonstrated that SAW sensors can differentiate between compounds with similar composition, structure, and polarity. These efforts, however, can be enhanced by using sensor arrays and smart data processing systems. Secondly, ionic interactions provide a convenient way to fabricate thin films for sensor applications. The potential of these thin films for sensor applications is currently being evaluated. 3 figs.
Date: December 31, 1998
Creator: Li, DeQuan
Partner: UNT Libraries Government Documents Department

Cleareye In-Ground and In-Concrete DIV Inspections: FY11 Final Report

Description: This report summarizes the results of a series of feasibility testing studies for in-ground and in-concrete imaging/detection technologies including radar imaging and acoustic time-of flight method. The objectives of this project are: (1) Design Information Verification (DIV) Tools for In-Concrete Inspections - To determine the feasibility of using holographic radar imaging (HRI), radar imaging, and acoustic time-of-flight (TOF) non-destructive evaluation technologies to detect, locate and identify pipes and voids embedded in standard-density and high-density concrete walls that typify those the IAEA will need to verify during field inspections; (2) DIV Tools for In-Ground Inspections - To determine the feasibility of using HRI and radar imaging non-destructive evaluation technologies to detect, locate, and identify objects buried at various depths made of various materials (metal, plastic, wood, and concrete) and representing geometries that typify those the IAEA will need to verify during field inspections; and (3) Based on the results of the studies, recommend the next steps needed to realize fieldable tools for in-concrete and in-ground inspections (including detection of deeply buried polyvinyl chloride [PVC] pipes) that employ the technologies shown to be feasible.
Date: January 23, 2012
Creator: Braatz, Brett G.; Tedeschi, Jonathan R.; Denslow, Kayte M.; Morra, Marino; Knopik, Clint D.; Severtsen, Ronald H. et al.
Partner: UNT Libraries Government Documents Department

Feasibility of Large-Scale Ocean CO2 Sequestration

Description: This report covers research accomplished during CY 2006 under a modification of a previous award. During this period we completed analysis of the acoustic detection and modeling of a rising deep-sea liquid CO{sub 2} plume, and published the results in a major journal. The results are applicable to detection of leakage of CO{sub 2} from the sea floor, either from natural CO{sub 2} vents, or from purposefully disposed CO{sub 2} in sub-sea geologic formations. In April 2006 we executed, in collaboration with colleagues from Massachusetts Institute of Technology, Oak Ridge National Laboratory, and Canada a novel at sea experiment on the creation of a sinking plume of a CO{sub 2} hydrate composite paste, extruded through nozzles designed by ORNL. The work showed that a sinking, and slowly dissolving, mass can be created at depths where the pure liquid (above) would rise far and fast. In August 2006 we executed a cruise to the massive exposed methane hydrates in Barkley Canyon, off-shore Vancouver Island. There we cored the exposed hydrates, and exposed the specimens on the sea floor at 850m depth to liquid CO{sub 2} in a 3 liter closed container. The object was to examine possible inter-conversion of methane hydrate to CO{sub 2} hydrate with liberation of methane gas, and sequestration of the CO{sub 2} as a solid. Each of these complex experiments was successfully executed and the results reported in major journals and/or at national meetings.
Date: September 30, 2006
Creator: Brewer, Peter G.
Partner: UNT Libraries Government Documents Department

Survival Rates of Juvenile Salmonids Passing Through the Bonneville Dam and Spillway in 2008

Description: This report describes a 2008 acoustic telemetry survival study conducted by the Pacific Northwest National Laboratory for the Portland District of the U.S. Army Corps of Engineers. The study estimated the survival of juvenile Chinook salmon and steelhead passing Bonneville Dam (BON) and its spillway. Of particular interest was the relative survival of smolts detected passing through end spill bays 1-3 and 16-18, which had deep flow deflectors immediately downstream of spill gates, versus survival of smolts passing middle spill bays 4-15, which had shallow flow deflectors.
Date: December 28, 2009
Creator: Ploskey, Gene R.; Weiland, Mark A.; Faber, Derrek M.; Deng, Zhiqun; Johnson, Gary E.; Hughes, James S. et al.
Partner: UNT Libraries Government Documents Department

Parameter optimization of a microfabricated surface acoustic wave sensor for inert gas detection

Description: This work is related to designing, fabricating, and testing a surface acoustic wave sensor to be used for detecting metastable inert gases, particularly helium. The assembly consists of two microsensor configurations: (a) a reference device with no deposition at the delay line and (b) a sensing device with an Au-activated TiO{sub 2} e-beam-deposited thin film on the delay line. The interdigitated transducers and delay lines are fabricated by photolithography techniques on a single Y-cut LiNbO{sub 3} substrate oriented for Z-propagation of the acoustic waves. Variation in electrical conductivity of the Au-activated TiO{sub 2} film due to exposure to metastable He is translated as a frequency change in the assembly. Various characteristics of the surface acoustic microsensor have been studied to better understand and optimize the variation of acoustic wave velocity and the operating frequency of the microdevice. Methods for the TiO{sub 2} thin-film deposition are discussed.
Date: December 31, 1996
Creator: Ahuja, S.; Ross, C.; Chien, H.T. & Raptis, A.C.
Partner: UNT Libraries Government Documents Department

Acoustic resonance for nonmetallic mine detection

Description: The feasibility of acoustic resonance for detection of plastic mines was investigated by researchers at the Oak Ridge National Laboratory`s Instrumentation and Controls Division under an internally funded program. The data reported in this paper suggest that acoustic resonance is not a practical method for mine detection. Representative small plastic anti-personnel mines were tested, and were found to not exhibit detectable acoustic resonances. Also, non-metal objects known to have strong acoustic resonances were tested with a variety of excitation techniques, and no practical non-contact method of exciting a consistently detectable resonance in a buried object was discovered. Some of the experimental data developed in this work may be useful to other researchers seeking a method to detect buried plastic mines. A number of excitation methods and their pitfalls are discussed. Excitation methods that were investigated include swept acoustic, chopped acoustic, wavelet acoustic, and mechanical shaking. Under very contrived conditions, a weak response that could be attributed to acoustic resonance was observed, but it does not appear to be practical as a mine detection feature. Transfer properties of soil were investigated. Impulse responses of several representative plastic mines were investigated. Acoustic leakage coupling, and its implications as a disruptive mechanism were investigated.
Date: April 1, 1998
Creator: Kercel, S. W.
Partner: UNT Libraries Government Documents Department

Dual SAW sensor technique for determining mass and modulus changes in thin silicate films during gas adsorption

Description: Surface acoustic wave (SAW) sensors, which are sensitive to a variety of surface changes, have been widely used for chemical and physical sensing. The ability to control or compensate for the many surface forces has been instrumental in collecting valid data. In cases where it is not possible to neglect certain effects, such as frequency drift with temperature, methods such as the dual sensor technique have been utilized. This paper describes a novel use of a dual sensor technique, using two sensor materials, Quartz and GaAs, to separate out the contributions of mass and modulus of the frequency change during gas adsorption experiments. The large modulus change in the film calculated using this technique, and predicted by the Gassmann equation, provide a greater understanding of the challenges of SAW sensing.
Date: January 10, 2000
Creator: Hietala, S.L.; Hietala, V.M. & Brinker, C.J.
Partner: UNT Libraries Government Documents Department

Acoustic detection of Immiscible Liquids in Sand

Description: Laboratory cross-well P-wave transmission at 90 kHz was measured in a 61 cm diameter by 76 cm tall water-saturated sand pack, before and after introducing a non-aqueous phase organic liquid (NAPL) (n-dodecane). In one experiment NAPL was introduced to form a lens trapped by a low permeability layer; a second experiment considered NAPL residual trapped behind the front of flowing NAPL. The NAPL caused significant changes in the travel time and amplitude of first arrivals, as well as the generation of diffracted waves arriving after the direct wave. The spatial variations in NAPL saturation obtained from excavation at the end of the experiment correlated well with the observed variations in the P-wave amplitudes and travel times. NAPL residual saturation changes from NAPL flow channels of 3 to 4% were detectable and the 40 to 80% NAPL saturation in the NAPL lens was clearly visible at acoustic frequencies. The results of these experiments demonstrate that small NAPL saturations may be more easily detected with amplitude rather than travel time data, but that the relationships between the amplitude changes and NAPL saturation maybe more complex than those for velocity.
Date: March 1, 1999
Creator: Geller, Jil T.; Kowalsky, Michael B.; Seifert, Patricia K. & Nihei, Kurt T.
Partner: UNT Libraries Government Documents Department

Seismic and acoustic signal identification algorithms

Description: This paper will describe an algorithm for detecting and classifying seismic and acoustic signals for unattended ground sensors. The algorithm must be computationally efficient and continuously process a data stream in order to establish whether or not a desired signal has changed state (turned-on or off). The paper will focus on describing a Fourier based technique that compares the running power spectral density estimate of the data to a predetermined signature in order to determine if the desired signal has changed state. How to establish the signature and the detection thresholds will be discussed as well as the theoretical statistics of the algorithm for the Gaussian noise case with results from simulated data. Actual seismic data results will also be discussed along with techniques used to reduce false alarms due to the inherent nonstationary noise environments found with actual data.
Date: April 3, 2000
Creator: LADD,MARK D.; ALAM,M. KATHLEEN; SLEEFE,GERARD E. & GALLEGOS,DANIEL E.
Partner: UNT Libraries Government Documents Department

Laser-induced breakdown system for colloid characterization in dilute aqueous suspensions

Description: Detection and sizing of colloids by acoustic detection of laser-induced breakdown and elemental analysis of colloids by laser-induced breakdown spectroscopy are investigated in dilute aqueous suspensions. Development and testing of the methods are performed with standard polystyrene suspensions and prepared suspensions of defined composition and particle size. Application of the methods to analysis of field and laboratory samples is discussed. Am atomic emission lines are observed by laser-induced breakdown spectroscopy of an Am hydroxycarbonate suspension.
Date: August 11, 1999
Creator: Brachman, A; Mihardja, S; Palmer, C A & Wruck, D
Partner: UNT Libraries Government Documents Department

Feasibility of High Frequency Acoustic Imaging for Inspection of Containments: Phase II

Description: The nuclear power industry is concerned with corrosive thinning of portions of the metallic pressure boundary, particularly in areas that are not directly accessible for inspection. This study investigated the feasibility of detecting these thickness degradations using ultrasonic imaging. A commercial ultrasonic system was used to carry out several full-scale, controlled laboratory experiments. Measurements of 0.5 MHz shear wave levels propagated in 25-mm-thick steel plate embedded in concrete showed 1.4-1.6 dB of signal loss for each centimeter of two-way travel in the steel plate (compared to previous numerical predictions of 3-4 dB), and 1.3 dB of signal loss per centimeter of two-way travel in steel plates embedded in concrete prior to setting of the concrete (i.e., plastic). Negligible losses were measured in plates with a decoupling treatment applied between the steel and concrete to simulate the unbonded portions of the pressure boundary. Scattered signals from straight slots of different size and shape were investigated. The return from a 4-mm-deep rectangular slots exhibited levels 23 dB down relative to incidence and 4-6 dB higher than those obtained from both ''v'' shaped and rounded slots of similar depth. The system displayed an input/output dynamic range of 125 dB and measurement variability less than 1-2dB. Based on these results, a 4-mm-deep, rounded degradation embedded 30 cm in concrete has expected returns of -73dB relative to the input and should therefore be detectable. Results of this and a prior study indicate that the technique has merit and should be developed more fully and demonstrated in the field.
Date: July 1, 1999
Creator: Rudzinsky, J.; Bondaryk, J. & Conti, M.
Partner: UNT Libraries Government Documents Department

Passive Acoustic Detection of Wind Turbine In-Flow Conditions for Active Control and Optimization

Description: Wind is a significant source of energy; however, the human capability to produce electrical energy still has many hurdles to overcome. One of these is the unpredictability of the winds in the atmospheric boundary layer (ABL). The ABL is highly turbulent in both stable and unstable conditions (based on the vertical temperature profile) and the resulting fluctuations can have a dramatic impact on wind turbine operation. Any method by which these fluctuations could be observed, estimated, or predicted could provide a benefit to the wind energy industry as a whole. Based on the fundamental coupling of velocity fluctuations to pressure fluctuations in the nearly incompressible flow in the ABL, This work hypothesizes that a ground-based array of infrasonic pressure transducers could be employed to estimate the vertical wind profile over a height relevant for wind turbines. To analyze this hypothesis, experiments and field deployments were conducted. Wind tunnel experiments were performed for a thick turbulent boundary layer over a neutral or heated surface. Surface pressure and velocity probe measurements were acquired simultaneously. Two field deployments yielded surface pressure data from a 49 element array. The second deployment at the Reese Technology Center in Lubbock, TX, also included data from a smaller aperture, 96-element array and a 200-meter tall meteorological tower. Analysis of the data successfully demonstrated the ability to estimate the vertical velocity profile using coherence data from the pressure array. Also, dynamical systems analysis methods were successful in identifying and tracking a gust type event. In addition to the passive acoustic profiling method, this program also investigated a rapid response Doppler SODAR system, the optimization of wind turbine blades for enhanced power with reduced aeroacoustic noise production, and the implementation of a wireless health monitoring system for the wind turbine blades. Each of these other objectives was met successfully. ...
Date: March 12, 2012
Creator: Murray, Nathan E.
Partner: UNT Libraries Government Documents Department

R AND D 100 EARLYBIRD AWARD ENTRY

Description: The Smart Latch{trademark} is an electronically enhanced door lockset device for industrial and consumer applications, which uses existing neural network technology to analyze the sequence, timing, and acoustic signatures associated with lockset functions and provides immediate indication of failure to correctly lock and latch. It essentially ''listens'' to and learns the sequences and acoustic signatures associated with lockset function and latching. When triggered by specific door activity the Smart Latch{trademark} begins analyzing sequences, frequencies and other parameters. With a satisfactory outcome the device provides positive feedback (e.g. visual and/or audible) and returns to a ''sleep'' state awaiting the next activity. If any part of the normal door operation, including latching and length of time, are incorrect various alarm signals can be generated. With electronics and 5+ year battery integrated, the device is simple to install and transparent to the user. Because the device uses proven voice recognition algorithms, it could meet or exceed the performance of the human ear in detecting the unique and complex acoustic signature associated with a properly operating and secured door. Unlike existing technologies, such as limit switches, it is not easily spoofed or defeated and has a high level of immunity to interference. The Smart Latch{trademark} technology can be integrated into existing lockset and door hardware designs, including both low price consumer products and high end electronic/cipher locks. The concept and design are based on a simple security industry adage: ''It isn't locked if it isn't latched''. Even the most elaborate and robust security barriers are of little use if the locking and latching mechanisms are not properly functioning and engaged. Smart Latch{trademark} provides automatic verification of the first and most important step in facility security: Close and properly latch doors and barriers. It is a compelling product for households with children, elderly, or high ...
Date: January 30, 2007
Creator: Dugan, J & Debbie Chapman, D
Partner: UNT Libraries Government Documents Department

A comparison of the response of a captive carried store to both reverberant and progressive wave acoustic excitation

Description: Stores carried on high performance military aircraft are exposed to severe vibroacoustic environments which are caused by several different sources. Two methods available for simulating the acoustic portion of this environment in the laboratory are reverberant chambers and progressive wave tubes. The literature indicates that structures will respond differently to each of these acoustic sources as a function of frequency for the same Sound Pressure Level. Sandia National Laboratories participated in a test program that obtained acoustic data for a common store using both types of acoustic excitation. The purpose of this paper is to present the results from those tests in such a way so as to document the existence or absence of any significant differences in the coupling efficiencies for these acoustic sources.
Date: December 31, 1995
Creator: Cap, J.S.
Partner: UNT Libraries Government Documents Department

Gas sensing with acoustic devices

Description: A survey is made of acoustic devices that are suitable as gas and vapor sensors. This survey focuses on attributes such as operating frequency, mass sensitivity, quality factor (Q), and their ability to be fabricated on a semiconductor substrate to allow integration with electronic circuitry. The treatment of the device surface with chemically-sensitive films to detect species of interest is discussed. Strategies for improving discrimination are described, including sensor arrays and species concentration and separation schemes. The advantages and disadvantages of integrating sensors with microelectronics are considered, along with the effect on sensitivity of scaling acoustic gas sensors to smaller size.
Date: December 31, 1996
Creator: Martin, S.J.; Frye, G.C.; Spates, J.J. & Butler, M.A.
Partner: UNT Libraries Government Documents Department

Acoustic resonance spectroscopy (ARS): ARS300 operations manual, software version 2.01

Description: Acoustic Resonance Spectroscopy (ARS) is a nondestructive evaluation technology developed at the Los Alamos National Laboratory. The ARS technique is a fast, safe, and nonintrusive technique that is particularly useful when a large number of objects need to be tested. Any physical object, whether solid, hollow, or fluid filled, has many modes of vibration. These modes of vibration, commonly referred to as the natural resonant modes or resonant frequencies, are determined by the object`s shape, size, and physical properties, such as elastic moduli, speed of sound, and density. If the object is mechanically excited at frequencies corresponding to its characteristic natural vibrational modes, a resonance effect can be observed when small excitation energies produce large amplitude vibrations in the object. At other excitation frequencies, i.e., vibrational response of the object is minimal.
Date: July 25, 1996
Partner: UNT Libraries Government Documents Department

Infrasound records from U.S. atmospheric tests

Description: The United States conducted over 100 atmospheric nuclear tests at the Nevada Test Site from 1951 through 1962. Some of the earliest tests caused unexpected damage, primarily broken glass and cracked plaster, in Las Vegas and other surrounding communities. To address this problem, Sandia initiated a program to monitor and predict the pressure waves around NTS. Infrasound recording systems were developed, then field for all tests beginning with Operation Buster in October 1951. Investigators soon discovered that near-surface temperature inversions and wind profiles caused the damaging pressures in Las Vegas. A typical test was recorded at about a dozen stations from the Control Point on NTS to as far away as Pasadena, CA. In addition, some tests in the South Pacific were monitored, as well as numerous chemical explosions. Strip charts recorded signals in the frequency band from 0.05 to 30 Hz, and the paper tapes were achieved at Sandia in the early 1970s. The NTS events ranged in yield from below 1 ton to 74 kilotons; source altitudes varied from near ground level (including some cratering experiments) to as high as 11 km. The resulting data contain a wealth of information on the source function, yield scaling and regional propagation of infrasound signals from atmospheric explosions. The renewed interest in infrasonic monitoring for CTBT verification has prompted the authors to exhume some of the archived records. The authors plan to digitize the signals from several tests and evaluate their applicability to CTBT issues. In addition, they will collect any existing parametric measurements for these records (arrival times, amplitudes, etc.). All data will be converted to CSS database format and made available to the research community. If appropriate, the resulting information could also be included in the Knowledge Base under development for CTBT monitoring.
Date: July 1, 1998
Creator: Chael, E.P. & Lohr, R.D.
Partner: UNT Libraries Government Documents Department