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An improved strategy to detect CO2 leakage for verification ofgeologic carbon sequestration

Description: To detect and quantify subtle surface CO2 leakage signals, we present a strategy that combines measurements of CO2 fluxes or concentrations in the near-surface environment with an algorithm that enhances temporally- and spatially-correlated leakage signals while suppressing random background noise. The algorithm consists of a filter that highlights spatial coherence in the leakage signal, and temporal stacking (averaging) that reduces noise from temporally uncorrelated background fluxes/concentrations. We assess the performance of our strategy using synthetic data sets in which the surface leakage signal is either specified directly or calculated using flow and transport simulations of leakage source geometries one might expect to be present at sequestration sites. We estimate the number of measurements required to detect a potential CO2 leakage signal of given magnitude and area. Results show that given a rigorous field-sampling program, subtle CO2 leakage may be detected using the algorithm; however, leakage of very limited spatial extent or exceedingly small magnitude may be difficult to detect with a reasonable set of monitoring resources.
Date: May 11, 2006
Creator: Lewicki, Jennifer L.; Hilley, George E. & Oldenburg, Curtis M.
Partner: UNT Libraries Government Documents Department

Noise Reduction with Microphone Arrays for Speaker Identification

Description: Reducing acoustic noise in audio recordings is an ongoing problem that plagues many applications. This noise is hard to reduce because of interfering sources and non-stationary behavior of the overall background noise. Many single channel noise reduction algorithms exist but are limited in that the more the noise is reduced; the more the signal of interest is distorted due to the fact that the signal and noise overlap in frequency. Specifically acoustic background noise causes problems in the area of speaker identification. Recording a speaker in the presence of acoustic noise ultimately limits the performance and confidence of speaker identification algorithms. In situations where it is impossible to control the environment where the speech sample is taken, noise reduction filtering algorithms need to be developed to clean the recorded speech of background noise. Because single channel noise reduction algorithms would distort the speech signal, the overall challenge of this project was to see if spatial information provided by microphone arrays could be exploited to aid in speaker identification. The goals are: (1) Test the feasibility of using microphone arrays to reduce background noise in speech recordings; (2) Characterize and compare different multichannel noise reduction algorithms; (3) Provide recommendations for using these multichannel algorithms; and (4) Ultimately answer the question - Can the use of microphone arrays aid in speaker identification?
Date: December 22, 2011
Creator: Cohen, Z
Partner: UNT Libraries Government Documents Department

Subspace Detectors: Efficient Implementation

Description: The optimum detector for a known signal in white Gaussian background noise is the matched filter, also known as a correlation detector [Van Trees, 1968]. Correlation detectors offer exquisite sensitivity (high probability of detection at a fixed false alarm rate), but require perfect knowledge of the signal. The sensitivity of correlation detectors is increased by the availability of multichannel data, something common in seismic applications due to the prevalence of three-component stations and arrays. When the signal is imperfectly known, an extension of the correlation detector, the subspace detector, may be able to capture much of the performance of a matched filter [Harris, 2006]. In order to apply a subspace detector, the signal to be detected must be known to lie in a signal subspace of dimension d {ge} 1, which is defined by a set of d linearly-independent basis waveforms. The basis is constructed to span the range of signals anticipated to be emitted by a source of interest. Correlation detectors operate by computing a running correlation coefficient between a template waveform (the signal to be detected) and the data from a window sliding continuously along a data stream. The template waveform and the continuous data stream may be multichannel, as would be true for a three-component seismic station or an array. In such cases, the appropriate correlation operation computes the individual correlations channel-for-channel and sums the result (Figure 1). Both the waveform matching that occurs when a target signal is present and the cross-channel stacking provide processing gain. For a three-component station processing gain occurs from matching the time-history of the signals and their polarization structure. The projection operation that is at the heart of the subspace detector can be expensive to compute if implemented in a straightforward manner, i.e. with direct-form convolutions. The purpose of this report ...
Date: July 26, 2006
Creator: Harris, D B & Paik, T
Partner: UNT Libraries Government Documents Department

Wideband Multichannel Time-Reversal Processing for Acoustic Communications in a Tunnel-like Structure

Description: The development of multichannel time-reversal (T/R) processing techniques continues to progress rapidly especially when the need to communicate in a highly reverberative environment becomes critical. The underlying T/R concept is based on time-reversing the Green's function characterizing the uncertain communications channel investigating the deleterious dispersion and multipath effects. In this paper, attention is focused on two major objectives: (1) wideband communications leading to a time reference modulation technique; and (2) multichannel acoustic communications in a tunnel (or cave or pipe) with many obstructions, multipath returns, severe background noise, disturbances, long propagation paths ({approx}180) with disruptions (bends). For this extremely hostile environment, it is shown that multichannel T/R receivers can easily be extended to the wideband designs while demonstrating their performance in both the ''canonical'' stairwell of our previous work as well as a tunnel-like structure. Acoustic information signals are transmitted with an 8-element host or base station array to two client receivers with a significant loss in signal levels due to the propagation environment. In this paper, the results of the new wideband T/R processor and modulation scheme are discussed to demonstrate the overall performance for both high (24-bit) and low (1-bit) bit level analog-to-digital (A/D) converter designs. These results are validated by performing proof-of-principle acoustic communications experiments in air. It is shown that the resulting T/R receivers are capable of extracting the transmitted coded sequence from noisy microphone array measurements with zero-bit error.
Date: January 12, 2006
Creator: Candy, J V; Chambers, D H; Robbins, C L; Guidry, B L; Poggio, A J; Dowla, F et al.
Partner: UNT Libraries Government Documents Department

Pinhole aperture point backlighter development experiments on Trident, 9-13, 2001

Description: Pinhole aperture point backlighter (PAPBL) imaging has been used on experiments on Omega, but results have been compromised by large backgrounds. This technique has advantages over traditional area backlighting/pinhole imaging, and the Omega experiments could benefit from this capability, but Omega time is expensive and not the place for developing diagnostic techniques if they can be developed on Trident instead. PAPBL, shot from Direct Drive Cylinder Mix experiments on Omega (DDCYLMIX 00-1, January 18 and 19, 2000). [See LA-UR-00-4187, Post-Shot Report, Direct Drive Cylinder Mix]. In this campaign, they used Trident to obtain clean PAPBL images. Having accomplished that, they attempted to replicate the noise environment of Omega by producing hot electrons and having them impinge on material to produce high-energy x-rays similar to those that might be produced by hot electrons impinging on diagnostics or target positioner components on Omega. Backlighter target design was based, to some degree, on that shown by Bullock et al. at the 42nd Annual APS-DPP Meeting in Quebec City, Quebec, Canada, October 23-27, 2000. [A.B. Bullock et al., Bull. Am. Phys. Soc. 45,(7) 359 (2000); A.B. Bullock et al., Rev. Sci. Instrum. 72, 690 (2001).] We accomplished this to some degree and then attempted, with some success, to obtain a good PAPBL image in the presence of this noise. Results of this work suggest methods that might reduce the background noise in Omega PAPBL images. The goals are to obtain a pinhole aperture point backlighter (PAPBL) image on Trident and develop a method to simulate the high-energy background contribution to PAPBL imnages seen on Omega experients in order to allow future experiments to optimize signal-to-noise in PAPBL imaging.
Date: January 1, 2001
Creator: Lanier, N. E. (Nicholas E.) & Murphy, Thomas J.
Partner: UNT Libraries Government Documents Department

Background noise spectra of global seismic stations

Description: Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefits those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.
Date: August 1, 1996
Creator: Wada, M.M. & Claassen, J.P.
Partner: UNT Libraries Government Documents Department

Preliminary noise survey and data report of Saudi Arabian data

Description: From November 1995 to March 1996 a total of 9 broadband temporary stations were deployed across Saudi Arabian shield. These stations consisted of STS-2 seismometers recorded continuously at 40 sps on RefTek dataloggers. All installations were at bedrock sites. Using data sections selected randomly during the deployment, noise studies showed that most stations were exceptionally quiet with noise level near the USGS low noise model for frequencies higher than 0.1 Hz. At lower frequencies, the horizontal components showed increased noise levels, possibly due to instrumental characteristics. High-frequency (greater than 1 Hz) noise varied as much as 10 db between day and night for some stations (RAYN, TAIF) while more isolated stations (HALM) were constant. Seasonal noise levels also varied, with April to June being the quietest months. Slight changes in peak microseism frequency also occurred seasonally.
Date: August 1, 1997
Creator: Mellors, R.
Partner: UNT Libraries Government Documents Department

Clutter sensitivity test under controlled field conditions Resonant Microstrip Patch Antenna (RMPA) sensor technology

Description: Theoretical research, controlled laboratory tests, and these field test results show that nonmetallic (and metallic) shallowly buried objects can be detected and imaged with the Resonant Microstrip Patch Antenna (RMPA) sensor. The sensor can be modeled as a high Q cavity which capitalizes on its resonant condition sensitivity to scattered waves from buried objects. When the RMPA sensor is swept over a shallowly buried object, the RMPA fed-point impedance (resistance), measured with a Maxwell bridge, changes by tens of percent. The significant change in unprocessed impedance data can be presented in two-dimensional and three-dimensional graphical displays over the survey area. This forms silhouette images of the objects without the application of computationally intensive data processing algorithms. Because RMPA employed electromagnetic waves to illuminate the shallowly buried object, a number of questions and issues arise in the decision to fund or deny funding of the reconfiguration of the RMPA technology into a nonmetallic (metallic) land mine detector.
Date: June 27, 1996
Partner: UNT Libraries Government Documents Department

A study of betatron and momentum collimators in RHIC

Description: Two separate accelerator rings in the Relativistic Heavy Ion Collider (RHIC) will provide collisions between equal and unequal heavy ion species up to the gold ions, including the two polarized proton beams. There are six interaction points with two regions with {beta}* = 1--2 m occupied by the large detectors PHENIX and STAR. The transverse and longitudinal emittances of the gold ions are expected to double in size between one to two hours due to intra-beam scattering which may lead to transverse beam loss. Primary betatron collimators are positioned in the ring where the betatron functions have large values to allow efficient removal of particles with large betatron amplitudes. In this report the authors investigated distributions and losses coming from the out-scattered particles from the primary collimators, as well as the best positions for the secondary momentum and betatron collimators. Additional studies of the detector background due to beam halo and other details about the collimation in RHIC are reported elsewhere, while more information about the momentum collimation was previously reported in Momentum Collimation at Q9 by S. Peggs and G.F. Dell.
Date: December 1, 1997
Creator: Trbojevic, D.; Stevens, A.J. & Harrison, M.
Partner: UNT Libraries Government Documents Department

Local Area Signal-to-Noise Ratio (LASNR) algorithm for Image Segmentation

Description: Many automated image-based applications have need of finding small spots in a variably noisy image. For humans, it is relatively easy to distinguish objects from local surroundings no matter what else may be in the image. We attempt to capture this distinguishing capability computationally by calculating a measurement that estimates the strength of signal within an object versus the noise in its local neighborhood. First, we hypothesize various sizes for the object and corresponding background areas. Then, we compute the Local Area Signal to Noise Ratio (LASNR) at every pixel in the image, resulting in a new image with LASNR values for each pixel. All pixels exceeding a pre-selected LASNR value become seed pixels, or initiation points, and are grown to include the full area extent of the object. Since growing the seed is a separate operation from finding the seed, each object can be any size and shape. Thus, the overall process is a 2-stage segmentation method that first finds object seeds and then grows them to find the full extent of the object. This algorithm was designed, optimized and is in daily use for the accurate and rapid inspection of optics from a large laser system (National Ignition Facility (NIF), Lawrence Livermore National Laboratory, Livermore, CA), which includes images with background noise, ghost reflections, different illumination and other sources of variation.
Date: July 3, 2007
Creator: Kegelmeyer, L; Fong, P; Glenn, S & Liebman, J
Partner: UNT Libraries Government Documents Department

Improving Ventilation and Saving Energy: Final Report on Indoor Environmental Quality and Energy Monitoring in Sixteen Relocatable Classrooms

Description: An improved HVAC system for portable classrooms was specified to address key problems in existing units. These included low energy efficiency, poor control of and provision for adequate ventilation, and excessive acoustic noise. Working with industry, a prototype improved heat pump air conditioner was developed to meet the specification. A one-year measurement-intensive field-test of ten of these IHPAC systems was conducted in occupied classrooms in two distinct California climates. These measurements are compared to those made in parallel in side by side portable classrooms equipped with standard 10 SEER heat pump air conditioner equipment. The IHPAC units were found to work as designed, providing predicted annual energy efficiency improvements of about 36 percent to 42 percent across California's climate zones, relative to 10 SEER units. Classroom ventilation was vastly improved as evidenced by far lower indoor minus outdoor CO2 concentrations. TheIHPAC units were found to provide ventilation that meets both California State energy and occupational codes and the ASHRAE minimum ventilation requirements; the classrooms equipped with the 10 SEER equipment universally did not meet these targets. The IHPAC system provided a major improvement in indoor acoustic conditions. HVAC system generated background noise was reduced in fan-only and fan and compressor modes, reducing the nose levels to better than the design objective of 45 dB(A), and acceptable for additional design points by the Collaborative on High Performance Schools. The IHPAC provided superior ventilation, with indoor minus outdoor CO2 concentrations that showed that the Title 24 minimum ventilation requirement of 15 CFM per occupant was nearly always being met. The opposite was found in the classrooms utilizing the 10 SEER system, where the indoor minus outdoor CO2 concentrations frequently exceeded levels that reflect inadequate ventilation. Improved ventilation conditions in the IHPAC lead to effective removal of volatile organic compounds and aldehydes, on ...
Date: April 4, 2008
Creator: Apte, Michael G.; Norman, Bourassa; Faulkner, David; Hodgson, Alfred T.; Hotchi, Toshfumi; Spears, Michael et al.
Partner: UNT Libraries Government Documents Department

Development of Powder Diffraction Analysis Tools for aNanocrystalline Specimen: An Emphasis upon NiTi (Nitinol)

Description: Powder diffraction is a specialized technique whose investigatory limits are constrained by the scale of the crystallized substance being scanned versus the probe beam used. When disparate in scale, with the photon spot size larger than the crystal being probed, many are employed, the resulting diffraction image being cast from all possible incident angles, constructing {chi}-arcs containing information about the crystalline structure of the material under examination. Of particular interest to our collaboration is the structure of Nitinol, a superelastic Nickel-Titanium alloy, whose phase transformations and load bearing deformations can be studied by usage of diffraction, with wide sweeping biomedical uses. Analysis of this data is complicated by phase transformation and material fluorescence, which make difficult the computational modeling of the peaks within concentric {chi}-arcs. We endeavored to construct a series of computational tools (the amalgamation of them known as 2DPeakFinder) for refining and extracting this relevant data, toward the end of employing previously developed algorithms in the material's structural analysis. We succeeded to a large degree with the use of an iterative algorithm to navigate radial complexity of the signal and manage to retain a distinction between useful signal and superfluous background noise. The tools developed in this project are a small step in readily streamlining the analysis and physical modeling of a Nanocrystalline material's structural properties.
Date: August 30, 2006
Creator: Owens, Erich & /SLAC, /Albion Coll.
Partner: UNT Libraries Government Documents Department

MODEL-BASED HYDROACOUSTIC BLOCKAGE ASSESSMENT AND DEVELOPMENT OF AN EXPLOSIVE SOURCE DATABASE

Description: We are continuing the development of the Hydroacoustic Blockage Assessment Tool (HABAT) which is designed for use by analysts to predict which hydroacoustic monitoring stations can be used in discrimination analysis for any particular event. The research involves two approaches (1) model-based assessment of blockage, and (2) ground-truth data-based assessment of blockage. The tool presents the analyst with a map of the world, and plots raypath blockages from stations to sources. The analyst inputs source locations and blockage criteria, and the tool returns a list of blockage status from all source locations to all hydroacoustic stations. We are currently using the tool in an assessment of blockage criteria for simple direct-path arrivals. Hydroacoustic data, predominantly from earthquake sources, are read in and assessed for blockage at all available stations. Several measures are taken. First, can the event be observed at a station above background noise? Second, can we establish backazimuth from the station to the source. Third, how large is the decibel drop at one station relative to other stations. These observational results are then compared with model estimates to identify the best set of blockage criteria and used to create a set of blockage maps for each station. The model-based estimates are currently limited by the coarse bathymetry of existing databases and by the limitations inherent in the raytrace method. In collaboration with BBN Inc., the Hydroacoustic Coverage Assessment Model (HydroCAM) that generates the blockage files that serve as input to HABAT, is being extended to include high-resolution bathymetry databases in key areas that increase model-based blockage assessment reliability. An important aspect of this capability is to eventually include reflected T-phases where they reliably occur and to identify the associated reflectors. To assess how well any given hydroacoustic discriminant works in separating earthquake and in-water explosion populations it is ...
Date: July 11, 2005
Creator: Matzel, E; Ramirez, A & Harben, P
Partner: UNT Libraries Government Documents Department

Application of Polynomial and Radial Basis Function Maps to Signal Masking

Description: The objective of this research was to develop and demonstrate a technique for encrypting information by using a masking signal that closely approximates local ambient noise. Signal masking techniques developed to date have used nonlinear differential equations, spread spectrum, and various modulation schemes to encode information. While these techniques can effectively hide a signal, the resulting masks may not appear as ambient noise to an observer. The advantage of the proposed technique over commonly used masking methods is that the transmitted signal will appear as normal background noise, thus greatly reducing the probability of detection and exploitation. A promising near-term application of this technology presents itself in the area of clandestine minefield reconnaissance in shallow water areas. Shallow water mine-counter-mine (SWMCM) activity is essential for minefield avoidance, efficient minefield clearance, and effective selection of transit lanes within minefields. A key technology area for SWMCM is the development of special sonar waveforms with low probability of exploitation/intercept (LPE/LPI) attributes. In addition to LPE/LPI sonar, this technology has the potential to enable significant improvements in underwater acoustic communications. For SWMCM, the chaotic waveform research provides a mechanism for encrypted communications between a submarine (SSN) and an unmanned underwater vehicle (UUV) via an acoustic channel. Acoustic SSN/UUV communications would eliminate the need for a fiberoptic link between the two vessels, thus increasing the robustness of SWMCM. Similar applications may exist in the areas of radar masking and secure communications. The original approach called for the use of polynomial maps to generate a masking signal. Because polynomial maps were found to have highly restrictive stability criteria, the approach was modified to use radial basis function (RBF) maps. they have shown that stable RBF maps that closely approximate an ambient sea state can be derived using nonlinear systems theory. In doing so, they have shown ...
Date: January 1, 1998
Creator: Damiano, B.
Partner: UNT Libraries Government Documents Department

Backgrounds and detector performance at a 2 x 2 TeV {mu}{sup +}{mu}{sup {minus}} collider

Description: The rich physics potential of a high-energy high-luminosity {mu}{sup +}{mu}{sup {minus}} collider and the surprising feasibility of a design attract the attention of many people these days. A few issues define the practicality of such a project, with the enormous particle background levels in a detector due to unavoidable reasons holding first place. In contrast to hadron colliders where particle backgrounds come both from interaction point (IP) and accelerator, almost all the backgrounds in the muon collider detectors arise in the machine. The decay length for 2 TeV muons is {lambda}{sub D}{sup {minus}1} {approximately}10{sup {minus}7} m{sup {minus}1}. With 10{sup 12} muons in a bunch one has 10{sup 5} decays per meter in a single pass through an interaction region, and 10{sup 8} decays per meter per 12 msec store. This paper examines two major classes of detector backgrounds presented in the muon collider: beam halo backgrounds, and the {open_quotes}direct{close_quotes} backgrounds from electrons from {mu}{yields}e{nu}{bar {nu}} decay occurring in the beam channel. The authors describe the nature of both of these backgrounds, provide results of first realistic calculations for both sources and discuss their effects on plausible detectors. Various shielding and collimation geometries have been simulated, and their efficacy and the nature of the surviving background discussed.
Date: March 1, 1995
Creator: Foster, G.W. & Mokhov, N.V.
Partner: UNT Libraries Government Documents Department

An analysis of background noise in selected canyons of Los Alamos County

Description: The authors recorded background noise levels in six canyons within Los Alamos County in order to establish a baseline for future comparisons and to discover what noises animals are exposed to. Noise level measurements were taken within each canyon, beginning at an established starting point and at one-mile intervals up to four miles. The primary source of noise above 55 dBA was vehicular traffic. One clap of thunder provided the highest recorded noise level (76 dBA). In general, the level of noise, once away from highways and parking lots, was well below 60 dBA.
Date: October 1, 1997
Creator: Huchton, K.; Koch, S.W. & Robinson, R.
Partner: UNT Libraries Government Documents Department

Analysis of the SIAM Infrared Acquisition System

Description: This report describes and presents the results of an analysis of the performance of the infrared acquisition system for a Self-Initiated Antiaircraft Missile (SIAM). A description of the optical system is included, and models of target radiant intensity, atmospheric transmission, and background radiance are given. Acquisition probabilities are expressed in terms of the system signal-to-noise ratio. System performance against aircraft and helicopter targets is analyzed, and background discrimination techniques are discussed. 17 refs., 22 figs., 6 tabs.
Date: February 1, 1974
Creator: Varnado, S.G.
Partner: UNT Libraries Government Documents Department

Reduction of background by higher order statistics with NMIS

Description: Measurements that accumulate the rate of real coincidence between multiplets of detection events (groupings of arbitrary order, e.g., one event, two events, three events, etc.) can yield spurious results if background events arise from processes (e.g., spontaneous fission or neutron spallation) that themselves produce correlated multiplets. This is particularly true if this background varies significantly over time or from one location to another, as it often does in operating facilities, i.e., those not specifically designed to support experimental radiation measurements but that instead rely upon the support of precise radiation measurements for, e.g., NMC and A. In particular, both the quantity and location of radioactive material in weapons facilities changes frequently and unpredictably, and so the background due to the presence (or absence) of this material is completely out of the control of the radiation measurement analyst. Furthermore, numerous Nuclear Materials Identification System (NMIS) measurements have revealed that background often contains mutually correlated events even in the complete absence of material (e.g., {sup 240}Pu) with a significant spontaneous fission rate. The technique subsequently described removes the effects of such self-correlated background from active NMIS measurements. It could be adapted to other active radiation measurements.
Date: July 11, 2000
Creator: Mattingly, J. K.; Mullens, J. A. & Mihalczo, J. T.
Partner: UNT Libraries Government Documents Department

ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT

Description: The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.
Date: December 1, 2004
Creator: Loth, John L.; Morris, Gary J.; Palmer, George M.; Guiler, Richard & Browning, Patrick
Partner: UNT Libraries Government Documents Department

ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT

Description: The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.
Date: October 31, 2004
Creator: Loth, John L.; Morris, Gary J.; Palmer, George M.; Guiler, Richard & Browning, Patrick
Partner: UNT Libraries Government Documents Department

Noise considerations in millimeter-wave spectrometers

Description: An improved version of a microwave spectrometer operating in the vicinity of 70 GHz is described. The spectrometer, which incorporates a Fabry-Perot resonator and superheterodyne detection for high sensitivity is designed for the detection of gaseous pollutants and other atmospheric constituents. The instrument is capable of detecting polar molecules with absorption coefficients as small as 2 x 10/sup -9/cm/sup -1/. For sulphur dioxide diluted in air, this sensitivity corresponds to a detection limit of 1.2 ppm without preconcentration and with a time constant of 1 second. Measurements and analysis of the noise contributions limiting the sentivity are presented.
Date: December 1, 1978
Creator: Zoellner, W.D.; Kolbe, W.F. & Leskovar, B.
Partner: UNT Libraries Government Documents Department

Noise reduction in negative-ion quadrupole mass spectrometry

Description: This invention is comprised of a quadrupole mass spectrometer (QMS) system having an ion source, quadrupole mass filter, and ion collector/recorder system. A weak, transverse magnetic field and an electron collector are disposed between the quadrupole and ion collector. When operated in negative ion mode, the ion source produces a beam of primarily negatively-charged particles from a sample, including electrons as well as ions. The beam passes through the quadrupole and enters the magnetic field, where the electrons are deflected away from the beam path to the electron collector. The negative ions pass undeflected to the ion collector where they are detected and recorded as a mass spectrum.
Date: December 31, 1991
Creator: Chastagner, P.
Partner: UNT Libraries Government Documents Department