Science.gov

Sample records for reducing noise emission

  1. QCGAT aircraft/engine design for reduced noise and emissions

    NASA Technical Reports Server (NTRS)

    Lanson, L.; Terrill, K. M.

    1980-01-01

    The high bypass ratio QCGAT engine played an important role in shaping the aircraft design. The aircraft which evolved is a sleek, advanced design, six-place aircraft with 3538 kg (7,800 lb) maximum gross weight. It offers a 2778 kilometer (1500 nautical mile) range with cruise speed of 0.5 Mach number and will take-off and land on the vast majority of general aviation airfields. Advanced features include broad application of composite materials and a supercritical wing design with winglets. Full-span fowler flaps were introduced to improve landing capability. Engines are fuselage-mounted with inlets over the wing to provide shielding of fan noise by the wing surfaces. The design objectives, noise, and emission considerations, engine cycle and engine description are discussed as well as specific design features.

  2. Analytic treatment of source photon emission times to reduce noise in implicit Monte Carlo calculations

    SciTech Connect

    Trahan, Travis J.; Gentile, Nicholas A.

    2012-09-10

    Statistical uncertainty is inherent to any Monte Carlo simulation of radiation transport problems. In space-angle-frequency independent radiative transfer calculations, the uncertainty in the solution is entirely due to random sampling of source photon emission times. We have developed a modification to the Implicit Monte Carlo algorithm that eliminates noise due to sampling of the emission time of source photons. In problems that are independent of space, angle, and energy, the new algorithm generates a smooth solution, while a standard implicit Monte Carlo solution is noisy. For space- and angle-dependent problems, the new algorithm exhibits reduced noise relative to standard implicit Monte Carlo in some cases, and comparable noise in all other cases. In conclusion, the improvements are limited to short time scales; over long time scales, noise due to random sampling of spatial and angular variables tends to dominate the noise reduction from the new algorithm.

  3. Noise Emission from Laboratory Air Blowers

    ERIC Educational Resources Information Center

    Rossing, Thomas D.; Windham, Betty

    1978-01-01

    Product noise ratings for a number of laboratory air blowers are reported and several recommendations for reducing laboratory noise from air blowers are given. Relevant noise ratings and methods for measuring noise emission of appliances are discussed. (BB)

  4. Noise Emission from Laboratory Air Blowers

    ERIC Educational Resources Information Center

    Rossing, Thomas D.; Windham, Betty

    1978-01-01

    Product noise ratings for a number of laboratory air blowers are reported and several recommendations for reducing laboratory noise from air blowers are given. Relevant noise ratings and methods for measuring noise emission of appliances are discussed. (BB)

  5. Reducing Printed Circuit Board Emissions with Low-Noise Design Practices

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T.; Fowler, Jennifer; Yavoich, Brian J.; Jennings, Stephen A.

    2012-01-01

    This paper presents the results of an experiment designed to determine the effectiveness of adopting several low-noise printed circuit board (PCB) design practices. Two boards were designed and fabricated, each consisting of identical mixed signal circuitry. Several important differences were introduced between the board layouts: one board was constructed using recommended low-noise practices and the other constructed without such attention. The emissions from the two boards were then measured and compared, demonstrating an improvement in radiated emissions of up to 22 dB.

  6. Evaluation of a Hydrogen Fuel Cell Powered Blended-Wing-Body Aircraft Concept for Reduced Noise and Emissions

    NASA Technical Reports Server (NTRS)

    Guynn, Mark D.; Freh, Joshua E.; Olson, Erik D.

    2004-01-01

    This report describes the analytical modeling and evaluation of an unconventional commercial transport aircraft concept designed to address aircraft noise and emission issues. A blended-wing-body configuration with advanced technology hydrogen fuel cell electric propulsion is considered. Predicted noise and emission characteristics are compared to a current technology conventional configuration designed for the same mission. The significant technology issues which have to be addressed to make this concept a viable alternative to current aircraft designs are discussed. This concept is one of the "Quiet Green Transport" aircraft concepts studied as part of NASA's Revolutionary Aerospace Systems Concepts (RASC) Program. The RASC Program was initiated to develop revolutionary concepts that address strategic objectives of the NASA Enterprises, such as reducing aircraft noise and emissions, and to identify advanced technology requirements for the concepts.

  7. Evaluation of an Aircraft Concept With Over-Wing, Hydrogen-Fueled Engines for Reduced Noise and Emissions

    NASA Technical Reports Server (NTRS)

    Guynn, Mark D.; Olson, Erik D.

    2002-01-01

    This report describes the analytical modeling and evaluation of an unconventional commercial transport aircraft concept designed to address aircraft noise and emission issues. A strut-braced wing configuration with overwing, ultra-high bypass ratio, hydrogen fueled turbofan engines is considered. Estimated noise and emission characteristics are compared to a conventional configuration designed for the same mission and significant benefits are identified. The design challenges and technology issues which would have to be addressed to make the concept a viable alternative to current aircraft designs are discussed. This concept is one of the "Quiet Green Transport" aircraft concepts studied as part of NASA's Revolutionary Aerospace Systems Concepts (RASC) Program. The RASC Program seeks to develop revolutionary concepts that address strategic objectives of the NASA Enterprises, such as reducing aircraft noise and emissions, and to identify enabling advanced technology requirements for the concepts.

  8. Ultra High Bypass Ratio Engine Research for Reducing Noise, Emissions, and Fuel Consumption

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.; Schweitzer, Jeff

    2007-01-01

    A pictorial history of NASA development of advanced engine technologies for reducing environmental emissions and increasing performance from the 1970s to 2000s is presented. The goals of the Subsonic Fixed Wing Program portion of the NASA Fundamental Aeronautics Program are discussed, along with the areas of investigation currently being pursued by the Ultra High Bypass Partnership Element of the Subsonic Fixed Wing Program.

  9. Noise Emission Assessment

    NASA Astrophysics Data System (ADS)

    Hübner, G.; Schorer, E.

    The acoustical efficiency of machines varies in the range of 10-9 to 10-5. This means even high power machines generate sound powers of a few Watts only. Due to the high sensitivity of the human ear however, such low sound powers create close to the machine loudnesses higher than 100 phon (64 sone). Consequently, the assessment of machinery noise emission requires relations to these subjective properties.

  10. Aerodynamic noise emission from turbulent shear layers.

    NASA Technical Reports Server (NTRS)

    Pao, S. P.

    1973-01-01

    The Phillips (1960) convected wave equation is employed in this paper to study aerodynamic noise emission processes in subsonic and supersonic shear layers. The wave equation in three spatial dimensions is first reduced to an ordinary differential equation by Fourier transformation and then solved via the WKBJ method. Three typical solutions are required for discussions in this paper. The current results are different from the classical conclusions. The effects of refraction, convection, Mach-number dependence and temperature dependence of turbulent noise emission are analyzed in the light of solutions to the Phillips equation.

  11. Collaborative Research on the Ultra High Bypass Ratio Engine Cycle to Reduce Noise, Emissions and Fuel Consumption

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher

    2008-01-01

    A pictorial history of NASA development of advanced engine technologies for reducing environmental emissions and increasing performance from the 1970s to present is presented. The goals of the Subsonic Fixed Wing Program portion of the NASA Fundamental Aeronautics Program are addressed, along with the areas of investigation currently being pursued by the Ultra High Bypass Partnership Element of the Subsonic Fixed Wing Program to meet the goals. Ultra High Bypass cycle research collaboration successes with Pratt & Whitney are presented.

  12. Emissions and Noise Pervasive Panel

    NASA Technical Reports Server (NTRS)

    Henderson, Brenda; Lee, Chi

    2008-01-01

    Objectives include: Provide interagency coordination of technology development, aimed at engine noise reduction. a) Provide recommendations to the Steering Committee on potential areas of interagency technology collaboration to maximize the use of government investments in noise reduction. b) Serve as a forum for information and technology exchange in order to coordinate gas turbine engine environmental strategies and policies among the member agencies and industry; c) Coordinate activities across panel representatives; and d) Communicate progress to VAATE steering committee.

  13. Quantum Noise from Reduced Dynamics

    NASA Astrophysics Data System (ADS)

    Vacchini, Bassano

    2016-07-01

    We consider the description of quantum noise within the framework of the standard Copenhagen interpretation of quantum mechanics applied to a composite system environment setting. Averaging over the environmental degrees of freedom leads to a stochastic quantum dynamics, described by equations complying with the constraints arising from the statistical structure of quantum mechanics. Simple examples are considered in the framework of open system dynamics described within a master equation approach, pointing in particular to the appearance of the phenomenon of decoherence and to the relevance of quantum correlation functions of the environment in the determination of the action of quantum noise.

  14. Radiated emission noise of the plasma

    NASA Astrophysics Data System (ADS)

    Ijichi, K.; Yoshida, T.; Kudo, I.; Kuriki, K.

    1982-11-01

    Measurement of the emission noise radiated by an MPD arcjet and an electron beam accelerator plasma in a large space chamber shows that such noise slightly exceeds current electromagnetic compatibility standards, although chamber wall reflection was incompatible with test specifications. No interference is expected for the case of S band communications links, although some may appear in UHF links. The Spacelab-1 Space Experiments with Particle Accelerators flight hardware employed in these tests exhibited no malfunctions.

  15. 40 CFR 205.152 - Noise emission standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Noise emission standards. 205.152 Section 205.152 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.152 Noise emission standards...

  16. Microwave Oscillator Would Have Reduced Phase Noise

    NASA Technical Reports Server (NTRS)

    Dick, G. John; Saunders, Jon

    1991-01-01

    Microwave oscillators of proposed new type incorporate suppressed-carrier/negative-feedback feature to reduce phase noise near their carrier frequencies. Concept results in phase noise less than achievable by cryogenically stabilized microwave components or by room-temperature oscillators stabilized by quartz crystals. Implemented in three different versions.

  17. Advanced flow noise reducing acoustic sensor arrays

    NASA Astrophysics Data System (ADS)

    Fine, Kevin; Drzymkowski, Mark; Cleckler, Jay

    2009-05-01

    SARA, Inc. has developed microphone arrays that are as effective at reducing flow noise as foam windscreens and sufficiently rugged for tough battlefield environments. These flow noise reducing (FNR) sensors have a metal body and are flat and conformally mounted so they can be attached to the roofs of land vehicles and are resistant to scrapes from branches. Flow noise at low Mach numbers is created by turbulent eddies moving with the fluid flow and inducing pressure variations on microphones. Our FNR sensors average the pressure over the diameter (~20 cm) of their apertures, reducing the noise created by all but the very largest eddies. This is in contrast to the acoustic wave which has negligible variation over the aperture at the frequencies of interest (f less or equal than 400 Hz). We have also post-processed the signals to further reduce the flow noise. Two microphones separated along the flow direction exhibit highly correlated noise. The time shift of the correlation corresponds to the time for the eddies in the flow to travel between the microphones. We have created linear microphone arrays parallel to the flow and have reduced flow noise as much as 10 to 15 dB by subtracting time-shifted signals.

  18. Sensors reduce car emissions

    SciTech Connect

    Paula, G.

    1996-11-01

    Advanced control and diagnostic sensors play a key role in antipollution devices such as catalytic converters, electronic fuel injection, and exhaust-gas recirculation systems. Technologies such as catalytic converters, electronic fuel injection, and exhaust-gas recirculation (EGR) systems have decreased automobile emissions approximately 90 percent from their 1960 levels. The cornerstone of many of these emissions-control technologies are sensors that provide feedback and control. Any sensor--particularly those installed under an automobile hood--must withstand harsh conditions, such as intense heat, shock, continual vibration, corrosive gases, and electromagnetic fields. As a result microelectromechanical-system sensors, though widely used in automobiles, have not been applied to emissions monitoring and pollution control because they are not rugged enough to survive inside an engine. Most automobile sensors use mature technologies, but newer technologies such as fiber-optic sensors will be installed in vehicles within the next few years.

  19. Engine Validation of Noise and Emission Reduction Technology Phase I

    NASA Technical Reports Server (NTRS)

    Weir, Don (Editor)

    2008-01-01

    This final report has been prepared by Honeywell Aerospace, Phoenix, Arizona, a unit of Honeywell International, Inc., documenting work performed during the period December 2004 through August 2007 for the NASA Glenn Research Center, Cleveland, Ohio, under the Revolutionary Aero-Space Engine Research (RASER) Program, Contract No. NAS3-01136, Task Order 8, Engine Validation of Noise and Emission Reduction Technology Phase I. The NASA Task Manager was Dr. Joe Grady of the NASA Glenn Research Center. The NASA Contract Officer was Mr. Albert Spence of the NASA Glenn Research Center. This report is for a test program in which NASA funded engine validations of integrated technologies that reduce aircraft engine noise. These technologies address the reduction of engine fan and jet noise, and noise associated with propulsion/airframe integration. The results of these tests will be used by NASA to identify the engineering tradeoffs associated with the technologies that are needed to enable advanced engine systems to meet stringent goals for the reduction of noise. The objectives of this program are to (1) conduct system engineering and integration efforts to define the engine test-bed configuration; (2) develop selected noise reduction technologies to a technical maturity sufficient to enable engine testing and validation of those technologies in the FY06-07 time frame; (3) conduct engine tests designed to gain insight into the sources, mechanisms and characteristics of noise in the engines; and (4) establish baseline engine noise measurements for subsequent use in the evaluation of noise reduction.

  20. 40 CFR 205.166 - Noise emission standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Noise emission standards. 205.166 Section 205.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle Exhaust Systems § 205.166 Noise...

  1. 40 CFR 205.166 - Noise emission standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Noise emission standards. 205.166 Section 205.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle Exhaust Systems § 205.166 Noise...

  2. 40 CFR 205.166 - Noise emission standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Noise emission standards. 205.166 Section 205.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle Exhaust Systems § 205.166 Noise...

  3. 40 CFR 205.166 - Noise emission standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Noise emission standards. 205.166 Section 205.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle Exhaust Systems § 205.166 Noise...

  4. 40 CFR 205.166 - Noise emission standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Noise emission standards. 205.166 Section 205.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle Exhaust Systems § 205.166 Noise...

  5. The control and optimization of environmental noise emissions from combustion turbine plants

    SciTech Connect

    Hessler, G.F. Jr.; Hessler, D.M.

    1996-12-31

    The methodology for performing an environmental noise assessment or impact study is reviewed to provide an overall framework for the importance of comprehensive noise control design for planned or existing combustion turbine facilities. Since ambient or background noise levels in residential communities usually drive the acoustical design goal for plant noise emissions, typical levels that can be expected are categorized. Noise emission criteria are discussed with regard to both satisfying mandated and responsible neighbor levels. Quantitative guidelines for designing plants to responsible neighbor levels are also examined. The principal equipment noise emissions sources are rank ordered for typical plants in the 25 to 100 MW size range. The basic acoustical engineering principles for predicting and modeling environmental noise emissions from complex arrangements of equipment are explained and illustrated. These principles are used to show that thoughtful siting or arrangement of equipment can often reduce, or at least minimize, the cost and performance penalties of noise mitigation measures.

  6. 40 CFR 205.52 - Vehicle noise emission standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Vehicle noise emission standards. 205.52 Section 205.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.52 Vehicle...

  7. 40 CFR 205.52 - Vehicle noise emission standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Vehicle noise emission standards. 205.52 Section 205.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.52 Vehicle...

  8. 40 CFR 205.52 - Vehicle noise emission standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Vehicle noise emission standards. 205.52 Section 205.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.52 Vehicle...

  9. 40 CFR 205.52 - Vehicle noise emission standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Vehicle noise emission standards. 205.52 Section 205.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.52 Vehicle...

  10. 40 CFR 205.52 - Vehicle noise emission standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Vehicle noise emission standards. 205.52 Section 205.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.52 Vehicle...

  11. Teleconsultations reduce greenhouse gas emissions.

    PubMed

    Oliveira, Tiago Cravo; Barlow, James; Gonçalves, Luís; Bayer, Steffen

    2013-10-01

    Health services contribute significantly to greenhouse gas emissions. New models of delivering care closer to patients have the potential to reduce travelling and associated emissions. We aimed to compare the emissions of patients attending a teleconsultation - an outpatient appointment using video-conferencing equipment - with those of patients attending a face-to-face appointment. We estimated the total distances travelled and the direct and indirect greenhouse gas emissions for 20,824 teleconsultations performed between 2004 and 2011 in Alentejo, a Portuguese region. These were compared to the distances and emissions that would have resulted if teleconsultations were not available and patients had to attend face-to-face outpatient appointments. Estimates were calculated using survey data on mode of transport, and national aggregate data for car engine size and fuel. A sensitivity analysis using the lower and upper quartiles for survey distances was performed. Teleconsultations led to reductions in distances and emissions of 95%. 2,313,819 km of travelling and 455 tonnes of greenhouse gas emissions were avoided (22 kg of carbon dioxide equivalent per patient). The incorporation of modes of transport and car engine size and fuel in the analysis led to emission estimates which were 12% smaller than those assuming all patients used an average car. The availability of remote care services can significantly reduce road travel and associated emissions. At a time when many countries are committed to reducing their carbon footprint, it is desirable to explore how these reductions could be incorporated into technology assessments and economic evaluations.

  12. Tail Rotor Airfoils Stabilize Helicopters, Reduce Noise

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Founded by former Ames Research Center engineer Jim Van Horn, Van Horn Aviation of Tempe, Arizona, built upon a Langley Research Center airfoil design to create a high performance aftermarket tail rotor for the popular Bell 206 helicopter. The highly durable rotor has a lifetime twice that of the original equipment manufacturer blade, reduces noise by 40 percent, and displays enhanced performance at high altitudes. These improvements benefit helicopter performance for law enforcement, military training, wildfire and pipeline patrols, and emergency medical services.

  13. Reducing traffic noise with quieter pavements

    NASA Astrophysics Data System (ADS)

    Donavan, Paul

    2005-09-01

    In recent years, interest has increased in the use of pavement type to reduce traffic noise. This has been driven by public concern over noise from freeways and state transportation agencies' interest in using pavement instead of sound walls to mitigate traffic noise. Beginnings of the recent interest go back to 1998 with the formation of the Institute for Safe, Quiet & Durable Highways at Purdue University and the initiation long-term research by the California Department of Transportation (Caltrans) on the effectiveness of quieter pavements. In 2002, the State of Arizona announced plans to overlay 115 miles of concrete freeway in the greater Phoenix area with a quieter asphalt rubber surface. This turned into the first Quiet Pavement Pilot Program in partnership between Federal Highway Administration (FHWA) and the Arizona Department of Transportation. Since that time, the FHWA in cooperation with the American Association of State Highway Transportation Agencies conducted a fact finding ``Scan'' tour in Europe to evaluate their quiet pavement technology and policy. This was followed by the first comparative tire/pavement noise testing in the US and Europe using the same procedures and test tires. The results, issues, and future directions surrounding these activities will be discussed.

  14. Spontaneous emission noise in long-range surface plasmon polariton waveguide based optical gyroscope.

    PubMed

    Wang, Yang-Yang; Zhang, Tong

    2014-09-19

    Spontaneous emission noise is an important limit to the performance of active plasmonic devices. Here, we investigate the spontaneous emission noise in the long-range surface plasmon-polariton waveguide based optical gyroscope. A theoretical model of the sensitivity is established to study the incoherent multi-beam interference of spontaneous emission in the gyroscope. Numerical results show that spontaneous emission produces a drift in the transmittance spectra and lowers the signal-to-noise-ratio of the gyroscope. It also strengthens the shot noise to be the main limit to the sensitivity of the gyroscope for high propagation loss. To reduce the negative effects of the spontaneous emission noise on the gyroscope, an external feedback loop is suggested to estimate the drift in the transmittance spectra and therefor enhance the sensitivity. Our work lays a foundation for the improvement of long-range surface plasmon-polariton gyroscope and paves the way to its practical application.

  15. Spontaneous emission noise in long-range surface plasmon polariton waveguide based optical gyroscope

    PubMed Central

    Wang, Yang-Yang; Zhang, Tong

    2014-01-01

    Spontaneous emission noise is an important limit to the performance of active plasmonic devices. Here, we investigate the spontaneous emission noise in the long-range surface plasmon-polariton waveguide based optical gyroscope. A theoretical model of the sensitivity is established to study the incoherent multi-beam interference of spontaneous emission in the gyroscope. Numerical results show that spontaneous emission produces a drift in the transmittance spectra and lowers the signal-to-noise-ratio of the gyroscope. It also strengthens the shot noise to be the main limit to the sensitivity of the gyroscope for high propagation loss. To reduce the negative effects of the spontaneous emission noise on the gyroscope, an external feedback loop is suggested to estimate the drift in the transmittance spectra and therefor enhance the sensitivity. Our work lays a foundation for the improvement of long-range surface plasmon-polariton gyroscope and paves the way to its practical application. PMID:25234712

  16. Reduced-Noise Gas Flow Design Guide Developed as a Noise-Control Design Tool for Meeting Glenn's Hearing Conservation and Community Noise Goals

    NASA Technical Reports Server (NTRS)

    Cooper, Beth A.

    2000-01-01

    A Reduced-Noise Gas Flow Design Guide has been developed for the NASA Glenn Research Center at Lewis Field by Nelson Acoustical Engineering of Elgin, Texas. Gas flow systems are a significant contributor to t he noise exposure landscape at Glenn. Because of the power of many of these systems, hearing conservation and community noise are importan t issues. The purpose of the Guide is to allow Glenn engineers and de signers to address noise emission and control at the design stage by using readily available system parameters. Although the Guide was deve loped with Glenn equipment and systems in mind, it is expected to hav e wide application in industry.

  17. Method of reducing impulsive noise in electromagnetic geophysical data

    SciTech Connect

    Spies, B.R.

    1990-07-31

    This patent describes a method of reducing impulsive noise in electromagnetic geophysical data. It comprises: providing receiving antenna means for receiving an electromagnetic signal. The receiving antenna means receiving impulsive noise; providing noise sensor means for receiving the impulsive noise and placing the noise sensor means so as to receive the impulsive noise that is received by the receiving antenna means and so as to minimize the reception of the electromagnetic signal; simultaneously receiving the electromagnetic signal with the receiving antenna means so as to create a signal record and receiving the impulsive noise with the noise sensor means so as to create a noise record; examining the noise record for occurrences of the impulsive noise by comparing the noise record with a threshold noise value and identifying those instances of time in which the noise record exceeds the threshold; removing those portions of the signal record which are simultaneous with the identified instances in which the noise records exceeds the threshold, wherein the signal record has reduced impulsive noise.

  18. A concept for a counterrotating fan with reduced tone noise

    NASA Technical Reports Server (NTRS)

    Dittmar, James H.

    1992-01-01

    As subsonic jet engine designs incorporate higher bypass ratios to reduce jet noise and increase engine cycle efficiency, the fan noise becomes a significant part of the perceived total noise. The conventional method of reducing fan tone noise is to design a low tip-speed device. An alternative approach of using a counterrotating fan with a high number of rotor blades is investigated in this report. The source of noise at the blade passing frequency of this device is the rotor-only mechanism, which is cut off for a subsonic tip speed rotor. The interaction noise occurs at twice the blade passing frequency, which, for this fan, was shifted high enough in frequency to be above the perceived noise rating range. The result was a counterrotating fan which had more potential for tone noise reduction than does the conventional fan. A potential broadband noise reduction was also indicated.

  19. Traffic noise reduces foraging efficiency in wild owls

    PubMed Central

    Senzaki, Masayuki; Yamaura, Yuichi; Francis, Clinton D.; Nakamura, Futoshi

    2016-01-01

    Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls’ ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls’ ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals, and highlights the possible pervasive impacts of noise. PMID:27537709

  20. Traffic noise reduces foraging efficiency in wild owls

    NASA Astrophysics Data System (ADS)

    Senzaki, Masayuki; Yamaura, Yuichi; Francis, Clinton D.; Nakamura, Futoshi

    2016-08-01

    Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls’ ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls’ ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals, and highlights the possible pervasive impacts of noise.

  1. Theoretical Optimization of Track Components to Reduce Rolling Noise

    NASA Astrophysics Data System (ADS)

    Vincent, N.; Bouvet, P.; Thompson, D. J.; Gautier, P. E.

    1996-05-01

    The control of railway rolling noise requires a reduction in wheel and track noise emission. In this paper, a parametric study of the possible minimization of the track sound power is presented. In an initial global approach, a number of potential variations in track parameters are assessed in terms of their likely effect on rolling noise. from this, two main themes are selected for deeper study by use of TWINS model. The first parameter considered is the stiffness and damping of the rail-pad. By reducing the pad stiffness, the noise radiation from the sleeper is reduced but that from the rail is increased, and vice versa. An optimum is found when the rail and sleeper components are equal, for which the track radiation is a minimum. Starting from one existing track design, this optimum pad stiffness has been derived for an example wheel. The second area investigated is the increase of the attenuation rate of rail vibrations by the addition of damping measures. The implementation of dynamic absorbers with a mass of 5 kg every sleeper bay (0.6 m) leads to predicted reductions of track radiation of 2 dB(A) if the rail-pad stiffness is already optimal. For softer pads a larger reduction has been found, but the total effect is less than the combined effect of first changing to the optimum pad stiffness and then adding absorbers. Globally, for ballasted track with bibloc concrete sleepers, a 2-6 dB(A) reduction in track sound power can be expected through a rail-pad optimization and/or the implementation of dynamic absorbers on the rail.

  2. Quantum noise and spatial emission properties of RCLEDs

    NASA Astrophysics Data System (ADS)

    Birkner, Richard; Kaiser, Joachim; ElsaBer, Wolfgang; Jung, Christian

    2004-09-01

    We present results of comprehensive investigations of the intensity noise and the angular-resolved spectral emission characteristics of resonant-cavity light-emitting diodes (RCLEDs), demonstrating an interesting interplay between these two properties. First, we find that the intensity noise of the investigated RCLEDs, detected within a full solid angle of detection, is up to -0.15 dB below the shot noise in a quite large pumping regime, i.e., we demonstrate the successful generation of squeezed states of light with these optoelectronic devices. Second, we investigate the spectral and angular emission characteristics and find that the cavity-like character of the Bragg mirrors and the quantum well active medium manifests itself in a blue shift of the central emission wavelength from 847 nm at zero degree to 825 nm at an emission angle of sixty degree. By varying the temperature we are able to detune the quantum-well emission wavelength and the cavity resonance wavelength and observe a broader angular intensity profile. Third, we measure the angular resolved intensity noise. Its super-shot noise behavior can be explained by anticorrelations between radial components of the output intensity emitted at different angles. Finally, the possible origin of the observed anticorrelations in the angular-resolved intensity noise, as well as possibilities for future trends, applications and the limitations of these non-classical states of light with respect to sensing and spectroscopic applications are discussed.

  3. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Low-noise-emission product... ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a) The..., determine whether such product is a low-noise-emission product. In doing so, he will determine if...

  4. 40 CFR 203.6 - Contracts for low-noise-emission products.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Contracts for low-noise-emission... ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.6 Contracts for low-noise-emission products. (a) Data relied upon by the Administrator in determining that a product is a certified low-noise-emission...

  5. Limiting valve noise in gas metering, reducing stations

    SciTech Connect

    Boyle, S.J.

    1996-07-01

    There are three general reasons why valve noise should be a concern. First, workplace noise can result in gradual, job-related hearing loss to employees over a period of years. Second, communities often have restrictions on acceptable levels, hours during which noise can occur, and factors like duration and frequency of noise. Last, extremely high noise levels can cause serious damage, failure and malfunction to valves, piping and related equipment. Special low noise valves make less noise than conventional valves. They use one of three design strategies: multipath--splitting the flow into many small orifices; multistage--splitting the pressure drop into a series of smaller steps; and multipath/multistage combined in a single unit. Another approach to reducing noise generation involves placing carefully sized static restrictors in the pipeline. The restrictor absorbs a portion of the system pressure drop, so the valve`s share of the drop is lowered. While the restrictor and valve both make noise, the net sound level is reduced. Another approach is to allow the noise to happen, then hide it. Some methods include: pipe insulation, thermal or acoustic; heavy wall pipe; buried valves; silences; and sound enclosures. These approaches can work in some cases, but caution must be used. The major drawback with all these approaches is that the damage potential associated with extreme noise, turbulence, and vibration still exists at some locations in the system.

  6. Noise of fan designed to reduce stator lift fluctuations

    NASA Technical Reports Server (NTRS)

    Dittmar, J. H.; Woodward, R. P.; Stakolich, E. G.

    1977-01-01

    An existing fan stage was redesigned to reduce stator lift fluctuations and was acoustically tested at three nozzle sizes for reduced noise generation. The lift fluctuations on the stator were reduced by increasing the stator cord, adjusting incidence angles, and adjusting the rotor velocity diagrams. Broadband noise levels were signficantly reduced in the middle to high frequencies. Blade passage tone sound power was not lessened, but decreases in the harmonics were observed. Aerodynamic improvements in both performance and efficiency were obtained.

  7. Identifying and reducing noise in psychophysiological recordings.

    PubMed

    Cutmore, T R; James, D A

    1999-05-01

    Psychophysiology continues to be a widely used methodology in the study of human behaviour, emotion and cognition. The new researcher is faced with a number of problems in the recording process since the desired physiological signal must be isolated from a variety of noise sources. Precautions and strategies that can be implemented in setting up the recording equipment and isolating the subject from interference are described. There are also a number of software techniques that can be applied to improve signal quality after the data have been acquired. An overview is provided of hardware and software methods used to maximise the signal quality.

  8. Nozzle Thrust Optimization While Reducing Jet Noise

    NASA Technical Reports Server (NTRS)

    Seiner, J. M.; Gilinsky, M. M.

    1995-01-01

    A Bluebell nozzle design concept is proposed for jet noise reduction with minimal thrust loss or even thrust augmentation. A Bluebell nozzle has a sinusoidal lip line edge (chevrons) and a sinusoidal cross section shape with linear amplitude increasing downstream in the divergent nozzle part (corrugations). The experimental tests of several Bluebell nozzle designs have shown nose reduction relative to a convergent-divergent round nozzle with design exhaust number M(e) = 1.5. The best design provides an acoustic benefit near 4dB with about 1 percent thrust augmentation. For subsonic flow ((M(e)= 0.6)), the tests indicated that the present method for design of Bluebell nozzles gives less acoustic benefit and in most cases jet noise increased. The proposed designs incorporate analytical theory and 2D and 3D numerical simulations. Full Navier-Stokes and Euler solvers were utilized. Boundary layer effects were used. Several different designs were accounted for in the Euler applications.

  9. 40 CFR Appendix I to Subparts D... - Motorcycle Noise Emission Test Procedures

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Motorcycle Noise Emission Test... AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle...—Motorcycle Noise Emission Test Procedures Appendix I-1 to Subparts D and E—Test Procedure for Street and off...

  10. 40 CFR Appendix I to Subparts D... - Motorcycle Noise Emission Test Procedures

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Motorcycle Noise Emission Test... AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle...—Motorcycle Noise Emission Test Procedures Appendix I-1 to Subparts D and E—Test Procedure for Street and off...

  11. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a) The...

  12. 40 CFR 203.6 - Contracts for low-noise-emission products.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Contracts for low-noise-emission products. 203.6 Section 203.6 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.6 Contracts for low-noise-emission products. (a) Data...

  13. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a) The...

  14. 40 CFR 203.6 - Contracts for low-noise-emission products.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Contracts for low-noise-emission products. 203.6 Section 203.6 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.6 Contracts for low-noise-emission products. (a) Data...

  15. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a) The...

  16. 40 CFR 203.6 - Contracts for low-noise-emission products.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Contracts for low-noise-emission products. 203.6 Section 203.6 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.6 Contracts for low-noise-emission products. (a) Data...

  17. 40 CFR 203.4 - Low-noise-emission product determination.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Low-noise-emission product determination. 203.4 Section 203.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.4 Low-noise-emission product determination. (a) The...

  18. 40 CFR 203.6 - Contracts for low-noise-emission products.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Contracts for low-noise-emission products. 203.6 Section 203.6 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS LOW-NOISE-EMISSION PRODUCTS § 203.6 Contracts for low-noise-emission products. (a) Data...

  19. 40 CFR Appendix I to Subparts D... - Motorcycle Noise Emission Test Procedures

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Motorcycle Noise Emission Test... AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle...—Motorcycle Noise Emission Test Procedures Appendix I-1 to Subparts D and E—Test Procedure for Street and off...

  20. Controlling Technically Produced Noise to Reduce Psychological Stress

    ERIC Educational Resources Information Center

    Carlestam, Gosta

    1973-01-01

    Discusses the causes and problems associated with increasing levels of noise pollution in urban societies. Particular attention is given to noise emanating from aircraft and to possible means of reducing this problem and its resulting psychological stress and social strain. (JR)

  1. Controlling Technically Produced Noise to Reduce Psychological Stress

    ERIC Educational Resources Information Center

    Carlestam, Gosta

    1973-01-01

    Discusses the causes and problems associated with increasing levels of noise pollution in urban societies. Particular attention is given to noise emanating from aircraft and to possible means of reducing this problem and its resulting psychological stress and social strain. (JR)

  2. Reducing noise in a Raman quantum memory.

    PubMed

    Bustard, Philip J; England, Duncan G; Heshami, Khabat; Kupchak, Connor; Sussman, Benjamin J

    2016-11-01

    Optical quantum memories are an important component of future optical and hybrid quantum technologies. Raman schemes are strong candidates for use with ultrashort optical pulses due to their broad bandwidth; however, the elimination of deleterious four-wave mixing noise from Raman memories is critical for practical applications. Here, we demonstrate a quantum memory using the rotational states of hydrogen molecules at room temperature. Polarization selection rules prohibit four-wave mixing, allowing the storage and retrieval of attenuated coherent states with a mean photon number 0.9 and a pulse duration 175 fs. The 1/e memory lifetime is 85.5 ps, demonstrating a time-bandwidth product of ≈480 in a memory that is well suited for use with broadband heralded down-conversion and fiber-based photon sources.

  3. Reducing emissions from uranium dissolving

    SciTech Connect

    Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

    1992-10-01

    This study was designed to assess the feasibility of decreasing NO[sub x] emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO[sub x] fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO[sub x] emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO[sub 2] which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  4. Reducing emissions from uranium dissolving

    SciTech Connect

    Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

    1992-10-01

    This study was designed to assess the feasibility of decreasing NO{sub x} emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO{sub x} fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO{sub x} emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO{sub 2} which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  5. Noise and Signal for Spectra of Intermittent Noiselike Emission

    NASA Astrophysics Data System (ADS)

    Gwinn, C. R.; Johnson, M. D.

    2011-05-01

    We show that intermittency of noiselike emission, after propagation through a scattering medium, affects the distribution of noise in the observed correlation function. Intermittency also affects correlation of noise among channels of the spectrum, but leaves the average spectrum, average correlation function, and distribution of noise among channels of the spectrum unchanged. Pulsars are examples of such sources: intermittent and affected by interstellar propagation. We assume that the source emits Gaussian white noise, modulated by a time envelope. Propagation convolves the resulting time series with an impulse-response function that represents effects of dispersion, scattering, and absorption. We assume that this propagation kernel is shorter than the time for an observer to accumulate a single spectrum. We show that rapidly varying intermittent emission tends to concentrate noise near the central lag of the correlation function. We derive mathematical expressions for this effect, in terms of the time envelope and the propagation kernel. We present examples, discuss effects of background noise, and compare our results with observations.

  6. NOISE AND SIGNAL FOR SPECTRA OF INTERMITTENT NOISELIKE EMISSION

    SciTech Connect

    Gwinn, C. R.; Johnson, M. D. E-mail: michaeltdh@physics.ucsb.edu

    2011-05-20

    We show that intermittency of noiselike emission, after propagation through a scattering medium, affects the distribution of noise in the observed correlation function. Intermittency also affects correlation of noise among channels of the spectrum, but leaves the average spectrum, average correlation function, and distribution of noise among channels of the spectrum unchanged. Pulsars are examples of such sources: intermittent and affected by interstellar propagation. We assume that the source emits Gaussian white noise, modulated by a time envelope. Propagation convolves the resulting time series with an impulse-response function that represents effects of dispersion, scattering, and absorption. We assume that this propagation kernel is shorter than the time for an observer to accumulate a single spectrum. We show that rapidly varying intermittent emission tends to concentrate noise near the central lag of the correlation function. We derive mathematical expressions for this effect, in terms of the time envelope and the propagation kernel. We present examples, discuss effects of background noise, and compare our results with observations.

  7. The investigation of noise attenuation by plants and the corresponding noise-reducing spectrum.

    PubMed

    Fan, Yang; Zhiyi, Bao; Zhujun, Zhu; Jiani, Liu

    2010-04-01

    As noise pollution is becoming more and more serious, many researchers are studying the noise attenuation effect provided by plants. This article examines six kinds of evergreens as research subjects so as to compare the different arrangements and densities of plants and their effect on noise attenuation. The authors studied the relationship between each of the plant's characteristics (the characteristics include leaf area, leaf fresh weight, leaf tactility, and leaf shape) and their average relative noise attenuation (deltaLAep). The authors then generated the noise-reducing spectrum of the six plants. The results show that there is a notable difference in noise-reducing effects for low frequency and high frequency (p < .05) when the plants are arranged differently. Also, every plant demonstrates a specific noise-reducing spectrum. By quantifying noise attenuation characteristics and abilities of plants, the authors combine noise attenuation species to achieve the mutual benefits of plant varieties and establish an ecotypic sound barrier model with effective density and arrangement.

  8. Novel active noise-reducing headset using earshell vibration control.

    PubMed

    Rafaely, Boaz; Carrilho, Joao; Gardonio, Paolo

    2002-10-01

    Active noise-reducing (ANR) headsets are available commercially in applications varying from aviation communication to consumer audio. Current ANR systems use passive attenuation at high frequencies and loudspeaker-based active noise control at low frequencies to achieve broadband noise reduction. This paper presents a novel ANR headset in which the external noise transmitted to the user's ear via earshell vibration is reduced by controlling the vibration of the earshell using force actuators acting against an inertial mass or the earshell headband. Model-based theoretical analysis using velocity feedback control showed that current piezoelectric actuators provide sufficient force but require lower stiffness for improved low-frequency performance. Control simulations based on experimental data from a laboratory headset showed that good performance can potentially be achieved in practice by a robust feedback controller, while a single-frequency real-time control experiment verified that noise reduction can be achieved using earshell vibration control.

  9. Reducing Emissions from Uranium Dissolving

    SciTech Connect

    Griffith, W.L.

    1992-01-01

    This study was designed to assess the feasibility of decreasing NO{sub x} emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. The trays are steam coil heated. The process has operated satisfactorily, with few difficulties, for decades. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO{sub x} fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO{sub x} emissions. Because NO{sub x} is hazardous, fumes should be suppressed whenever the electric blower system is inoperable. Because the tray dissolving process has worked well for decades, as much of the current capital equipment and operating procedures as possible were preserved. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO{sub 2}, which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  10. Auditory white noise reduces age-related fluctuations in balance.

    PubMed

    Ross, J M; Will, O J; McGann, Z; Balasubramaniam, R

    2016-09-06

    Fall prevention technologies have the potential to improve the lives of older adults. Because of the multisensory nature of human balance control, sensory therapies, including some involving tactile and auditory noise, are being explored that might reduce increased balance variability due to typical age-related sensory declines. Auditory white noise has previously been shown to reduce postural sway variability in healthy young adults. In the present experiment, we examined this treatment in young adults and typically aging older adults. We measured postural sway of healthy young adults and adults over the age of 65 years during silence and auditory white noise, with and without vision. Our results show reduced postural sway variability in young and older adults with auditory noise, even in the absence of vision. We show that vision and noise can reduce sway variability for both feedback-based and exploratory balance processes. In addition, we show changes with auditory noise in nonlinear patterns of sway in older adults that reflect what is more typical of young adults, and these changes did not interfere with the typical random walk behavior of sway. Our results suggest that auditory noise might be valuable for therapeutic and rehabilitative purposes in older adults with typical age-related balance variability.

  11. Evoked otoacoustic emissions in workers exposed to noise: A review

    PubMed Central

    Alcarás, Patrícia Arruda de Souza; Lüders, Débora; França, Denise Maria Vaz Romano; Klas, Regina Maria; Lacerda, Adriana Bender Moreira de; Gonçalves, Cláudia Giglio de Oliveira

    2012-01-01

    Summary Introduction: The otoacoustic emissions test is an essential tool in the evaluation of auditory function, since it allows the early detection of cochlear damage of occupational origin. Objective: To present a review of the literature and analyze the effectiveness of the clinical application of the otoacoustic emissions test in workers exposed to noise. Methods: A bibliographical search covering a period of 10 years was performed in the Virtual Health Library including published articles in national and international journals indexed in the internationally recognized databases for the health sciences, LILACS, SCIELO, and MEDLINE, using the terms “otoacoustic emissions” and “occupational exposure.” The type of published article (national/international), the type and intensity of the stimulus most commonly used for the evoked otoacoustic emissions, the gender and age of the subjects, and the conclusions from the retrospective studies were all taken into consideration. Results and Conclusions: A total of 19 articles were analyzed, 7 national and 12 international, covering subjects from 17 to 77 years of age, mostly men. The type of stimulus most commonly used for the evoked otoacoustic emissions was the distortion method (12). Through this review, we have concluded that testing of evoked otoacoustic emissions in workers exposed to noise is an important tool in the early diagnosis of noise-induced cochlear hearing disorders. PMID:25991982

  12. Policy Options for Reducing CO2 Emissions

    DTIC Science & Technology

    2008-02-01

    that they reduce emissions by more than one ton when they pay back the allowance loan. 35. See Catherine Kling and Jonathan Rubin, “ Bankable Permits...emissions and allowances (to determine compliance) at the end of each year. As under the SO2 trading program, the NOx allowances are bankable . In addition

  13. Passerine birds breeding under chronic noise experience reduced fitness.

    PubMed

    Schroeder, Julia; Nakagawa, Shinichi; Cleasby, Ian R; Burke, Terry

    2012-01-01

    Fitness in birds has been shown to be negatively associated with anthropogenic noise, but the underlying mechanisms remain obscure. It is however crucial to understand the mechanisms of how urban noise impinges on fitness to obtain a better understanding of the role of chronic noise in urban ecology. Here, we examine three hypotheses on how noise might reduce reproductive output in passerine birds: (H1) by impairing mate choice, (H2) by reducing territory quality and (H3) by impeding chick development. We used long-term data from an island population of house sparrows, Passer domesticus, in which we can precisely estimate fitness. We found that nests in an area affected by the noise from large generators produced fewer young, of lower body mass, and fewer recruits, even when we corrected statistically for parental genetic quality using a cross-fostering set-up, supporting H3. Also, individual females provided their young with food less often when they bred in the noisy area compared to breeding attempts by the same females elsewhere. Furthermore, we show that females reacted flexibly to increased noise levels by adjusting their provisioning rate in the short term, which suggests that noise may be a causal factor that reduces reproductive output. We rejected H1 and H2 because nestbox occupancy, parental body mass, age and reproductive investment did not differ significantly between noisy and quiet areas. OUR RESULTS SUGGEST A PREVIOUSLY UNDESCRIBED MECHANISM TO EXPLAIN HOW ENVIRONMENTAL NOISE CAN REDUCE FITNESS IN PASSERINE BIRDS: by acoustically masking parent-offspring communication. More importantly, using a cross-fostering set-up, our results demonstrate that birds breeding in a noisy environment experience significant fitness costs. Chronic noise is omnipresent around human habitation and may produces similar fitness consequences in a wide range of urban bird species.

  14. Passerine Birds Breeding under Chronic Noise Experience Reduced Fitness

    PubMed Central

    Schroeder, Julia; Nakagawa, Shinichi; Cleasby, Ian R.; Burke, Terry

    2012-01-01

    Background Fitness in birds has been shown to be negatively associated with anthropogenic noise, but the underlying mechanisms remain obscure. It is however crucial to understand the mechanisms of how urban noise impinges on fitness to obtain a better understanding of the role of chronic noise in urban ecology. Here, we examine three hypotheses on how noise might reduce reproductive output in passerine birds: (H1) by impairing mate choice, (H2) by reducing territory quality and (H3) by impeding chick development. Methodology/Principal Findings We used long-term data from an island population of house sparrows, Passer domesticus, in which we can precisely estimate fitness. We found that nests in an area affected by the noise from large generators produced fewer young, of lower body mass, and fewer recruits, even when we corrected statistically for parental genetic quality using a cross-fostering set-up, supporting H3. Also, individual females provided their young with food less often when they bred in the noisy area compared to breeding attempts by the same females elsewhere. Furthermore, we show that females reacted flexibly to increased noise levels by adjusting their provisioning rate in the short term, which suggests that noise may be a causal factor that reduces reproductive output. We rejected H1 and H2 because nestbox occupancy, parental body mass, age and reproductive investment did not differ significantly between noisy and quiet areas. Conclusions/Significance Our results suggest a previously undescribed mechanism to explain how environmental noise can reduce fitness in passerine birds: by acoustically masking parent–offspring communication. More importantly, using a cross-fostering set-up, our results demonstrate that birds breeding in a noisy environment experience significant fitness costs. Chronic noise is omnipresent around human habitation and may produces similar fitness consequences in a wide range of urban bird species. PMID:22808028

  15. Adaptive filter based two-probe noise suppression system for transient evoked otoacoustic emission detection.

    PubMed

    Subotić, Miško; Šarić, Zoran; Jovičić, Slobodan T

    2012-03-01

    Transient otoacoustic emission (TEOAE) is a method widely used in clinical practice for assessment of hearing quality. The main problem in TEOAE detection is its much lower level than the level of environmental and biological noise. While the environmental noise level can be controlled, the biological noise can be only reduced by appropriate signal processing. This paper presents a new two-probe preprocessing TEOAE system for suppression of the biological noise by adaptive filtering. The system records biological noises in both ears and applies a specific adaptive filtering approach for suppression of biological noise in the ear canal with TEOAE. The adaptive filtering approach includes robust sign error LMS algorithm, stimuli response summation according to the derived non-linear response (DNLR) technique, subtraction of the estimated TEOAE signal and residual noise suppression. The proposed TEOAE detection system is tested by three quality measures: signal-to-noise ratio (S/N), reproducibility of TEOAE, and measurement time. The maximal TEOAE detection improvement is dependent on the coherence function between biological noise in left and right ears. The experimental results show maximal improvement of 7 dB in S/N, improvement in reproducibility near 40% and reduction in duration of TEOAE measurement of over 30%.

  16. Low frequency noise peak near magnon emission energy in magnetic tunnel junctions

    SciTech Connect

    Liu, Liang; Xiang, Li; Guo, Huiqiang; Wei, Jian; Li, D. L.; Yuan, Z. H.; Feng, J. F. Han, X. F.; Coey, J. M. D.

    2014-12-15

    We report on the low frequency (LF) noise measurements in magnetic tunnel junctions (MTJs) below 4 K and at low bias, where the transport is strongly affected by scattering with magnons emitted by hot tunnelling electrons, as thermal activation of magnons from the environment is suppressed. For both CoFeB/MgO/CoFeB and CoFeB/AlO{sub x}/CoFeB MTJs, enhanced LF noise is observed at bias voltage around magnon emission energy, forming a peak in the bias dependence of noise power spectra density, independent of magnetic configurations. The noise peak is much higher and broader for unannealed AlO{sub x}-based MTJ, and besides Lorentzian shape noise spectra in the frequency domain, random telegraph noise (RTN) is visible in the time traces. During repeated measurements the noise peak reduces and the RTN becomes difficult to resolve, suggesting defects being annealed. The Lorentzian shape noise spectra can be fitted with bias-dependent activation of RTN, with the attempt frequency in the MHz range, consistent with magnon dynamics. These findings suggest magnon-assisted activation of defects as the origin of the enhanced LF noise.

  17. Framing sound: Using expectations to reduce environmental noise annoyance.

    PubMed

    Crichton, Fiona; Dodd, George; Schmid, Gian; Petrie, Keith J

    2015-10-01

    Annoyance reactions to environmental noise, such as wind turbine sound, have public health implications given associations between annoyance and symptoms related to psychological distress. In the case of wind farms, factors contributing to noise annoyance have been theorised to include wind turbine sound characteristics, the noise sensitivity of residents, and contextual aspects, such as receiving information creating negative expectations about sound exposure. The experimental aim was to assess whether receiving positive or negative expectations about wind farm sound would differentially influence annoyance reactions during exposure to wind farm sound, and also influence associations between perceived noise sensitivity and noise annoyance. Sixty volunteers were randomly assigned to receive either negative or positive expectations about wind farm sound. Participants in the negative expectation group viewed a presentation which incorporated internet material indicating that exposure to wind turbine sound, particularly infrasound, might present a health risk. Positive expectation participants viewed a DVD which framed wind farm sound positively and included internet information about the health benefits of infrasound exposure. Participants were then simultaneously exposed to sub-audible infrasound and audible wind farm sound during two 7 min exposure sessions, during which they assessed their experience of annoyance. Positive expectation participants were significantly less annoyed than negative expectation participants, while noise sensitivity only predicted annoyance in the negative group. Findings suggest accessing negative information about sound is likely to trigger annoyance, particularly in noise sensitive people and, importantly, portraying sound positively may reduce annoyance reactions, even in noise sensitive individuals. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. [An intervention policy for reducing noise pollution in urban areas].

    PubMed

    Cosa, M; Cosa, G

    1989-01-01

    The methodological methods for a reduction of the noise pollution in the urban areas, mainly, can be advised in 8 operative points: 1) reduction of the source's noise; 2) control of the traffic; 3) planning of the urban and regional development; 4) building's shelter against the noise; 5) compensation's and incentivation's interventions for the exposed people; 6) controls activity and restaining of the noise's sources; 7) scientific research; 8) health education. For executive motivations we must, necessarily, divide the intervention turned to a reduction of the noise's emissions caused by fixed source compared to the noise's emissions determined by motor or railway traffic (mobile sources). This operative criteria have been utilized recently (1988) from Italian Department of Ecology for a bill. The controls of fixed source are made by Public Health Services of U.S.L. (Local Sanitary Unit) assisted, in case, by multiarea country's districts. The regulations of traffic can be took in consideration, in short time, only in more simple problems, as the setting up of pedestrian island or the suspensions of the heavy traffic, etc. The traffic's regulation must care same general data: the halved of traffic's flow in same rilevation's point, involve a reduction of only 3 dBA of the sound pressure level previously measured; if the percentage of heavy traffic is higher than 10% of the traffic's flow, the first intervention must be the no thorough fare to heavy lorries. In general, then, the best way for the resolution of vehicular noise pollution is the noisy emission's control of the single vehicle, because only the regulation of traffic's flow doesn't suffice to realise a enough reduction of noise pollution. For the resolution of more complex problems is necessary a preliminary stage to study and to plan those before to can carry out a typology of intervention. This necessity is, of course, more expensive in time and money; in fact, the solution of the problem can be the

  19. Reducing low-frequency noise during reversible fluctuations

    NASA Astrophysics Data System (ADS)

    Chamberlin, Ralph V.

    2017-02-01

    The noise from most materials exhibits a power-spectral density that tends to diverge as S(f) ∝ 1/f at low frequencies, f. A fundamental mechanism for this 1/f noise comes from the thermodynamics of small systems applied to reversible fluctuations of nanometer-sized regions inside bulk samples. Here this "nanothermodynamics" is used to derive a nonlinear correction to Boltzmann's factor. Specifically: Boltzmann's factor comes from the first-order (linear) derivative of entropy with respect to energy, whereas the nonlinear correction comes from higher-order terms. The nonlinear correction is applied to Monte Carlo simulations of small regions in the Ising model, yielding a low-frequency crossover to white noise that keeps the power-spectral density finite as f → 0. It is shown that the low-frequency noise in the model is reduced by reducing the size of the regions.

  20. Application of Feedforward Adaptive Active-Noise Control for Reducing Blade Passing Noise in Centrifugal Fans

    NASA Astrophysics Data System (ADS)

    WU, J.-D.; BAI, M. R.

    2001-02-01

    This paper describes two configurations of feedforward adaptive active-noise control (ANC) technique for reducing blade passing noise in centrifugal fans. In one configuration, the control speaker is installed at the cut-off region of the fan, while in the other configuration at the exit duct. The proposed ANC system is based on the filtered-x least-mean-squares (FXLMS) algorithm with multi-sine synthesized reference signal and frequency counting and is implemented by using a digital signal processor (DSP). Experiments are carried out to evaluate the proposed system for reducing the noise at the blade passing frequency (BPF) and its harmonics at various flow speeds. The results of the experiment indicated that the ANC technique is effective in reducing the blade passing noise for two configurations by using the feedforward adaptive control.

  1. Reducing Indoor Noise Levels Using People's Perception on Greenery

    NASA Astrophysics Data System (ADS)

    Mediastika, Christina E.; Binarti, Floriberta

    2013-12-01

    Employees working in cubicles of open-plan offices in Indonesia were studied in regard to their perception on the ability of indoor greenery to reduce noise levels. Sansevieria trifasciata and Scindapsus sp were used. Each was placed in the cubicle and noise levels were measured without plants, with Sansevieria, and with Scindapsus in place. The meters showed very insignificant difference. However, responses to surveys indicated a perception of lower noise in the presence of greenery. This seemed to be supported by prior knowledge and preconception and may be useful in creating a "quieter" indoor environment.

  2. 40 CFR Appendix I to Subparts D and E - Motorcycle Noise Emission Test Procedures [Note

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Motorcycle Noise Emission Test... (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles Recall of noncomplying motorcycles; relabeling of mislabeled motorcycles. Appendix I to Subparts D and E—Motorcycle Noise...

  3. 40 CFR Appendix I to Subparts D and E - Motorcycle Noise Emission Test Procedures [Note

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Motorcycle Noise Emission Test... (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles Recall of noncomplying motorcycles; relabeling of mislabeled motorcycles. Appendix I to Subparts D and E—Motorcycle Noise...

  4. 40 CFR Appendix I to Subparts D and E - Motorcycle Noise Emission Test Procedures [Note

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Motorcycle Noise Emission Test... (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles Recall of noncomplying motorcycles; relabeling of mislabeled motorcycles. Appendix I to Subparts D and E—Motorcycle Noise...

  5. 40 CFR Appendix I to Subparts D and E - Motorcycle Noise Emission Test Procedures [Note

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Motorcycle Noise Emission Test... (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles Recall of noncomplying motorcycles; relabeling of mislabeled motorcycles. Appendix I to Subparts D and E—Motorcycle Noise...

  6. 40 CFR Appendix I to Subparts D and E - Motorcycle Noise Emission Test Procedures [Note

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Motorcycle Noise Emission Test... (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles Recall of noncomplying motorcycles; relabeling of mislabeled motorcycles. Appendix I to Subparts D and E—Motorcycle Noise...

  7. Reducing the ingress of urban noise through natural ventilation openings.

    PubMed

    Oldham, D J; de Salis, M H; Sharples, S

    2004-01-01

    For buildings in busy urban areas affected by high levels of road traffic noise the potential to use natural ventilation can be limited by excessive noise entering through ventilation openings. This paper is concerned with techniques to reduce noise ingress into naturally ventilated buildings while minimizing airflow path resistance. A combined experimental and theoretical approach to the interaction of airflow and sound transmission through ventilators for natural ventilation applications is described. A key element of the investigation has been the development of testing facilities capable of measuring the airflow and sound transmission losses for a range of ventilation noise control strategies. It is demonstrated that a combination of sound reduction mechanisms -- one covering low frequency sound and another covering high frequency sound -- is required to attenuate effectively noise from typical urban sources. A method is proposed for quantifying the acoustic performance of different strategies to enable comparisons and informed decisions to be made leading to the possibility of a design methodology for optimizing the ventilation and acoustic performance of different strategies. The need for employing techniques for combating low frequency sound in tandem with techniques for reducing high frequency sound in reducing the ingress of noise from urban sources such as road traffic to acceptable levels is demonstrated. A technique is proposed for enabling the acoustic and airflow performance of apertures for natural ventilation systems to be designed simultaneously.

  8. WDM optical steganography based on amplified spontaneous emission noise.

    PubMed

    Wu, Ben; Tait, Alexander N; Chang, Matthew P; Prucnal, Paul R

    2014-10-15

    We propose and experimentally demonstrate a wavelength-division multiplexed (WDM) optical stealth transmission system carried by amplified spontaneous emission (ASE) noise. The stealth signal is hidden in both time and frequency domains by using ASE noise as the signal carrier. Each WDM channel uses part of the ASE spectrum, which provides more flexibility to apply stealth transmission in a public network and adds another layer of security to the stealth channel. Multi-channel transmission also increases the overall channel capacity, which is the major limitation of the single stealth channel transmission based on ASE noise. The relations between spectral bandwidth and coherence length of ASE carrier have been theoretically analyzed and experimentally investigated.

  9. Optical steganography based on amplified spontaneous emission noise.

    PubMed

    Wu, Ben; Wang, Zhenxing; Tian, Yue; Fok, Mable P; Shastri, Bhavin J; Kanoff, Daniel R; Prucnal, Paul R

    2013-01-28

    We propose and experimentally demonstrate an optical steganography method in which a data signal is transmitted using amplified spontaneous emission (ASE) noise as a carrier. The ASE serving as a carrier for the private signal has an identical frequency spectrum to the existing noise generated by the Erbium doped fiber amplifiers (EDFAs) in the transmission system. The system also carries a conventional data channel that is not private. The so-called "stealth" or private channel is well-hidden within the noise of the system. Phase modulation is used for both the stealth channel and the public channel. Using homodyne detection, the short coherence length of the ASE ensures that the stealth signal can only be recovered if the receiver closely matches the delay-length difference, which is deliberately changed in a dynamic fashion that is only known to the transmitter and its intended receiver.

  10. The effects of temperature on supersonic jet noise emission

    NASA Technical Reports Server (NTRS)

    Seiner, John M.; Ponton, Michael K.; Jansen, Bernard J.; Lagen, Nicholas T.

    1992-01-01

    This paper examines the generation of sound produced by high temperature supersonic jets. In particular, the question of the importance of supersonic instability waves to noise emission is considered relative to the role of Kelvin-Helmholtz (K-H) instability waves. Here, these waves are taken to be synonymous with the Mach emission process. Jet total temperatures from 313 to 1534 K are investigated using an axisymmetric water cooled supersonic nozzle designed for Mach 2. The aerodynamic and acoustic results of this study indicate that the dominant noise contributors are the K-H waves over the entire temperature range. Good agreement between measured and numerically predicted plume properties are obtained and an elliptic nozzle is used to demonstrate reduction of the K-H waves.

  11. The effects of temperature on supersonic jet noise emission

    NASA Technical Reports Server (NTRS)

    Seiner, John M.; Ponton, Michael K.; Jansen, Bernard J.; Lagen, Nicholas T.

    1992-01-01

    This paper examines the generation of sound produced by high temperature supersonic jets. In particular, the question of the importance of supersonic instability waves to noise emission is considered relative to the role of Kelvin-Helmholtz (K-H) instability waves. Here, these waves are taken to be synonymous with the Mach emission process. Jet total temperatures from 313 to 1534 K are investigated using an axisymmetric water cooled supersonic nozzle designed for Mach 2. The aerodynamic and acoustic results of this study indicate that the dominant noise contributors are the K-H waves over the entire temperature range. Good agreement between measured and numerically predicted plume properties are obtained and an elliptic nozzle is used to demonstrate reduction of the K-H waves.

  12. Reducing exhaust gas emissions from Citydiesel busses

    NASA Astrophysics Data System (ADS)

    Mikkonen, Seppo

    The effect of fuel composition and exhaust gas aftertreatment on the emissions was measured from truck and bus engines. Possibilities to measure unregulated emissions (aldehydes, polyaromatic hydrocarbons, mutagenicity) were built. A reformulated diesel fuel 'Citydiesel' was developed. Citydiesel was able to reduce emissions compared to standard diesel fuel as follows: particulates by 10 to 30%, nitrogen oxides by 2 to 10%, sulphur dioxide by 97%, polyaromatic hydrocarbons (PAH) over 50%, mutagenicity of the exhaust particulates clearly, odor of the exhaust, and smoke after a cold start. The use of Citydiesel fuel reduces emissions of the existing vehicles immediately which is a remarkable benefit. The very low sulphur content (below 50 ppm) makes it possible to use oxidation. catalytic converters to reduce emissions of diesel vehicles. The new Euro 2 exhaust regulations coming into force during 1996 can be met with a modern diesel engine, Citydiesel fuel, and exhaust gas aftertreatment. Properties of Citydiesel fuel were verified in a three year field test with 140 city buses. Experience was good; e.g., engine oil change interval could be lengthened. Total value of the exhaust was estimated with different fuels and aftertreatment device in order to find out cheap ways to reduce emissions.

  13. Noise source emissions, Deaf Smith County site, Texas

    SciTech Connect

    Not Available

    1987-05-13

    Noise source data and use factors for modeling the noise environment expected from salt site repository activity were provided by Battelle Columbus Division. This report has been prepared for the purpose of documenting the development of the data provided to the Repository Project Management (RPM) organization. The data provided encompass all phases of activity from site preparation through construction of the exploratory shaft facility (ESF). Noise environments expected from construction and operation of transportation corridors associated with the activity were also modeled. The equipment inventory, including sound-power levels for each item, is included. Emission source terms provided by Parsons Brinckerhoff/PB-KBB for the ESF were used as a basis for the noise-source emission inventory development. Where available, research results containing complete spectra were used. In cases where complete data were not available, a sound-pressure spectrum was synthesized from a characteristic spectrum shape from a similar piece of equipment. For example, a front-shovel excavator might be approximated by data from a front-end loader of similar horsepower range. Sound-power-level spectra were then calculated from the sound-pressure-level data. 2 refs.

  14. Noise emission zones in an automobile sheet-metal pressing plant, a 25-year follow-up study at three locations in the plant.

    PubMed

    Brühl, P; Davidsson, C; Ivarsson, A

    1996-01-01

    The Volvo plant at Olofström, Sweden is engaged in the pressing and assembling of sheet-metal components for automobiles. During the past 25 years, determined efforts have been made to introduce less noisy methods of production and to limit the levels of noise emission in three large workshops at the plant. Noise levels were mapped with the aid of stationary noise measurements. The results are expressed in terms of noise emission zones and presented as noise contour maps. The investigations were made on four occasions between 1967 and 1991. Following the comparative area calculations of the noise emission zones, it was deduced that the noise levels had been significantly reduced, despite an increased production. The results show that noise reduction measures applied to the presses. An increase in automation in sheet-metal handling, improved quality in the pressing of components and changes in the range of products have contributed to the reduction of noise levels at the plant.

  15. Reducing luminance intensity can improve motion perception in noise

    PubMed Central

    Allard, Rémy; Arleo, Angelo

    2017-01-01

    Visual perception generally improves under brighter environments. For instance, motion sensitivity is known to improve with luminance intensity especially at high temporal frequencies. However, the current study counter-intuitively shows that increasing luminance intensity can impair motion sensitivity in noise. Motion sensitivity was measured with and without noise added to a drifting Gabor patch as a function of the temporal frequency and luminance intensity. As expected, motion sensitivity in absence of noise reached a ceiling performance at a relatively low luminance intensity (about 35 td) for low temporal frequencies and improved with luminance intensity up to the highest luminance intensity tested (353 td) for high temporal frequencies. In noise, reducing mean luminance intensity facilitated motion sensitivity (up to a factor of about 1.7) for temporal frequencies up to 7.5 Hz and impaired sensitivity at higher temporal frequencies (15 and 30 Hz). We conclude that reducing luminance intensity is effectively equivalent to applying a low-pass filter, which can improve motion sensitivity in noise to low and middle temporal frequencies. This counterintuitive facilitation effect can be explained by two known properties of the visual system: decreasing luminance intensity impairs the visibility of high temporal frequencies (equivalent to a low-pass filter) and motion detectors are broadly tuned. PMID:28220883

  16. Modeling Signal-to-Noise Ratio of Otoacoustic Emissions in Workers Exposed to Different Industrial Noise Levels

    PubMed Central

    Nassiri, Parvin; Zare, Sajad; Monazzam, Mohammad R.; Pourbakht, Akram; Azam, Kamal; Golmohammadi, Taghi

    2016-01-01

    Introduction: Noise is considered as the most common cause of harmful physical effects in the workplace. A sound that is generated from within the inner ear is known as an otoacoustic emission (OAE). Distortion-product otoacoustic emissions (DPOAEs) assess evoked emission and hearing capacity. The aim of this study was to assess the signal-to-noise ratio in different frequencies and at different times of the shift work in workers exposed to various levels of noise. It was also aimed to provide a statistical model for signal-to-noise ratio (SNR) of OAEs in different frequencies based on the two variables of sound pressure level (SPL) and exposure time. Materials and Methods: This case–control study was conducted on 45 workers during autumn 2014. The workers were divided into three groups based on the level of noise exposure. The SNR was measured in frequencies of 1000, 2000, 3000, 4000, and 6000 Hz in both ears, and in three different time intervals during the shift work. According to the inclusion criterion, SNR of 6 dB or greater was included in the study. The analysis was performed using repeated measurements of analysis of variance, spearman correlation coefficient, and paired samples t-test. Results: The results showed that there was no statistically significant difference between the three exposed groups in terms of the mean values of SNR (P > 0.05). Only in signal pressure levels of 88 dBA with an interval time of 10:30–11:00 AM, there was a statistically significant difference between the right and left ears with the mean SNR values of 3000 frequency (P = 0.038). The SPL had a significant effect on the SNR in both the right and left ears (P = 0.023, P = 0.041). The effect of the duration of measurement on the SNR was statistically significant in both the right and left ears (P = 0.027, P < 0.001). Conclusion: The findings of this study demonstrated that after noise exposure during the shift, SNR of OAEs reduced from the beginning to the end of the shift

  17. An evaluation of various concepts of reducing supersonic jet noise

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Manes, J. P.; Massey, K. C.; Calloway, A. B.

    1990-01-01

    Acoustic and flow visualization data from nozzles mounted on the same facility were acquired, and a total of 10 different concepts of jet noise suppression were evaluated relative to one another and also a round nozzle. All nozzles had the same exit area. The suppressors included noncircular shapes; nozzles fitted with notches, tabs, and ejectors; and coaxial rectangular nozzles. Narrow-band noise data were acquired by a microphone located in the plane of the jet exit. In general, it is found that, for a constant exit area, the round nozzle is the noisiest. Just about any modification of this round nozzle around its periphery reduces the broadband shock-associated noise and, in most instances, modifies the screech frequency and levels. Coaxial rectangular nozzles, nozzles fitted with two tabs and operated with ejectors, and a rectangular C-D nozzles with perforated walls are identified to be the most promising concepts worthy of further investigation.

  18. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.52...

  19. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.52...

  20. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.52...

  1. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.52...

  2. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.52...

  3. 75 FR 67634 - Compliance With Interstate Motor Carrier Noise Emission Standards: Exhaust Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-03

    ... Carrier Noise Emission Standards: Exhaust Systems AGENCY: Federal Motor Carrier Safety Administration, DOT... Motor Carrier Noise Emission Standards: Exhaust Systems,'' published on September 20, 2010, in the... to be noise dissipative devices. DATES: This rule is effective November 19, 2010. ADDRESSES: The...

  4. Low stimulus environments: reducing noise levels in continuing care

    PubMed Central

    Brown, Juliette; Fawzi, Waleed; Shah, Amar; Joyce, Margaret; Holt, Genevieve; McCarthy, Cathy; Stevenson, Carmel; Marange, Rosca; Shakes, Joy; Solomon-Ayeh, Kwesi

    2016-01-01

    In the low stimulus environment project, we aimed to reduce the levels of intrusive background noise on an older adult mental health ward, combining a very straightforward measure on decibel levels with a downstream measure of reduced distress and agitation as expressed in incidents of violence. This project on reducing background noise levels on older adult wards stemmed from work the team had done on reducing levels of violence and aggression. We approached the problem using quality improvement methods. Reducing harm to patients and staff is a strategic aim of our Trust and in our efforts we were supported by the Trust's extensive programme of quality improvement, including training and support provided by the Institute for Healthcare Improvement and the trust's own Quality Improvement team. Prior to the project we were running a weekly multi-disciplinary quality improvement group on the ward. We established from this a sub-group to address the specific problem of noise levels and invited carers of people with dementia on our ward to the group. The project was led by nursing staff. We used a noise meter app readily downloadable from the internet to monitor background noise levels on the ward and establish a baseline measure. As a group we used a driver diagram to identify an overall aim and a clear understanding of the major factors that would drive improvements. We also used a staff and carer survey to identify further areas to work on. Change ideas that came from staff and carers included the use of the noise meter to track and report back on noise levels, the use of posters to remind staff about noise levels, the introduction of a visual indication of current noise levels (the Yacker Tracker), the addition of relaxing background music, and adaptations to furniture and environment. We tested many of these over the course of nine months in 2015, using the iterative learning gained from multiple PDSA cycles. The specific aim was a decrease from above 60dB to

  5. Aircraft noise reduction technology. [to show impact on individuals and communities, component noise sources, and operational procedures to reduce impact

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Aircraft and airport noise reduction technology programs conducted by NASA are presented. The subjects discussed are: (1) effects of aircraft noise on individuals and communities, (2) status of aircraft source noise technology, (3) operational procedures to reduce the impact of aircraft noise, and (4) NASA relations with military services in aircraft noise problems. References to more detailed technical literature on the subjects discussed are included.

  6. Quantum-noise quenching in the correlated spontaneous-emission laser as a multiplicative noise process. I. A geometrical argument

    SciTech Connect

    Schleich, W.; Scully, M.O.

    1988-02-15

    We show, via simple geometrical arguments, the quantum-noise quenching in a correlated (spontaneous) emission laser (CEL). This noise quenching is a consequence of the correlation between noise sources which results in a multiplicative noise process. The steady-state distribution for the phase difference between the two electric fields in a CEL is compared and contrasted to that of a standard phase-locked laser. Noise quenching is shown to occur in the case of the CEL via an explicit solution of the Fokker-Planck equation.

  7. FETC Programs for Reducing Greenhouse Gas Emissions

    SciTech Connect

    Ruether, J.A.

    1998-02-01

    Mark Twain once quipped that everyone talks about the weather but no one does anything about it. With interest in global climate change on the rise, researchers in the fossil-energy sector are feeling the heat to provide new technology to permit continued use of fossil fuels but with reduced emissions of so-called `greenhouse gases.` Three important greenhouse gases, carbon dioxide, methane, and nitrous oxide, are released to the atmosphere in the course of recovering and combusting fossil fuels. Their importance for trapping radiation, called forcing, is in the order given. In this report, we briefly review how greenhouse gases cause forcing and why this has a warming effect on the Earth`s atmosphere. Then we discuss programs underway at FETC that are aimed at reducing emissions of methane and carbon dioxide.

  8. Aluminum: Reducing chloride emissions from aluminum production

    SciTech Connect

    Simon, P.

    1999-09-29

    Reynolds Metals Company (RMC), with assistance from a NICE{sup 3} grant, is developing for commercialization a closed-loop control process that greatly reduces chlorine emissions and increases plant efficiency while maintaining metal quality. The process still utilizes chlorine to remove impurities during aluminum processing, but is more effective than current methods. With the new technology chlorine in the stack is monitored and input chlorine is adjusted continuously. This optimization of chlorine use results in substantially less waste because less chlorine has to be bought or produced by aluminum manufacturers. This innovation is a significant improvement over conventional aluminum treatments, in which chlorine is injected in a more costly and wasteful manner. By the year 2010, the new technology has the potential to reduce the energy it takes to create chlorine by 8.4 billion Btu per year and to cut greenhouse gas emissions by 1,377 tons per year.

  9. Assessing the environmental impacts of aircraft noise and emissions

    NASA Astrophysics Data System (ADS)

    Mahashabde, Anuja; Wolfe, Philip; Ashok, Akshay; Dorbian, Christopher; He, Qinxian; Fan, Alice; Lukachko, Stephen; Mozdzanowska, Aleksandra; Wollersheim, Christoph; Barrett, Steven R. H.; Locke, Maryalice; Waitz, Ian A.

    2011-01-01

    With the projected growth in demand for commercial aviation, many anticipate increased environmental impacts associated with noise, air quality, and climate change. Therefore, decision-makers and stakeholders are seeking policies, technologies, and operational procedures that balance environmental and economic interests. The main objective of this paper is to address shortcomings in current decision-making practices for aviation environmental policies. We review knowledge of the noise, air quality, and climate impacts of aviation, and demonstrate how including environmental impact assessment and quantifying uncertainties can enable a more comprehensive evaluation of aviation environmental policies. A comparison is presented between the cost-effectiveness analysis currently used for aviation environmental policy decision-making and an illustrative cost-benefit analysis. We focus on assessing a subset of the engine NO X emissions certification stringency options considered at the eighth meeting of the International Civil Aviation Organization’s Committee on Aviation Environmental Protection. The FAA Aviation environmental Portfolio Management Tool (APMT) is employed to conduct the policy assessments. We show that different conclusions may be drawn about the same policy options depending on whether benefits and interdependencies are estimated in terms of health and welfare impacts versus changes in NO X emissions inventories as is the typical practice. We also show that these conclusions are sensitive to a variety of modeling uncertainties. While our more comprehensive analysis makes the best policy option less clear, it represents a more accurate characterization of the scientific and economic uncertainties underlying impacts and the policy choices.

  10. Options for reducing carbon dioxide emissions

    SciTech Connect

    Rosenfeld, A.H.; Price, L.

    1991-08-01

    Improvements in energy efficiency can significantly reduce the annual growth in greenhouse gas emissions. Such improvements occur when energy intensity is reduced; no reduction in energy services is required. Using the concept of cost of conserved energy'' to develop conservation supply curves similar to resource supply curves, researchers consistently find that electricity and natural gas savings of nearly 50% of current consumption are possible for US buildings. Such reductions in energy consumption directly reduce emissions of greenhouse gases. To capture these savings, we must continue to develop energy-efficient technologies and strategies. This paper describes three recent energy-efficient technologies that benefited from energy conservation research and development (R D) funding: high-frequency ballasts, compact fluorescent lamps, and low-emissivity windows. Other advanced technologies and strategies of spectrally selective windows, superwindows, electrochromic windows, advanced insulation, low-flow showerheads, improved recessed lamp fixtures, whitening surfaces and planting urban trees, daylighting, and thermal energy storage are also discussed. 33 refs., 9 figs., 3 tabs.

  11. Options for reducing carbon dioxide emissions

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Arthur H.; Price, Lynn

    1992-03-01

    Improvements in energy efficiency can significantly reduce the annual growth in greenhouse gas emissions. Such improvements occur when energy intensity is reduced; no reduction in energy services is required. Using the concept of ``cost of conserved energy'' to develop conservation supply curves similar to resource supply curves, researchers consistently find that electricity and natural gas savings of nearly 50% of current consumption are possible for U.S. buildings. Such reductions in energy consumption directly reduce emissions of greenhouse gases. To capture these savings, we must continue to develop energy-efficient technologies and strategies. This paper describes three recent energy-efficient technologies that benefitted from energy conservation research and development (R&D) funding: high-frequency ballasts, compact fluorescent lamps, and low-emissivity windows. Other advanced technologies and strategies of spectrally selective windows, superwindows, electrochromic windows, advanced insulation, low-flow showerheads, improved recessed lamp fixtures, whitening surfaces and planting urban trees, daylighting, and thermal energy storage are also discussed.

  12. Aircraft Geared Architecture Reduces Fuel Cost and Noise

    NASA Technical Reports Server (NTRS)

    2015-01-01

    In an effort to increase fuel efficiency and reduce noise in commercial airplanes, NASA aeronautics teamed up with East Hartford, Connecticut-based Pratt & Whitney through a Space Act Agreement to help the company increase the efficiency of its turbofan engine. The company's new PurePower line of engines is 15 percent more fuel-efficient and up to 75 percent quieter than its competitors.

  13. Reducing Noise in the MSU Daily Lower-Tropospheric Global Temperature Dataset

    NASA Technical Reports Server (NTRS)

    Christy, John R.; Spencer, Roy W.; McNider, Richard T.

    1995-01-01

    The daily global-mean values of the lower-tropospheric temperature determined from microwave emissions measured by satellites are examined in terms of their signal, noise, and signal-to-noise ratio. Daily and 30-day average noise estimates are reduced by, almost 50% and 35%, respectively, by analyzing and adjusting (if necessary) for errors due to (1) missing data, (2) residual harmonics of the annual cycle unique to particular satellites, (3) lack of filtering, and (4) spurious trends. After adjustments, the decadal trend of the lower-tropospheric global temperature from January 1979 through February 1994 becomes -0.058 C, or about 0.03 C per decade cooler than previously calculated.

  14. Reducing Noise in the MSU Daily Lower-Tropospheric Global Temperature Dataset

    NASA Technical Reports Server (NTRS)

    Christy, John R.; Spencer, Roy W.; McNider, Richard T.

    1996-01-01

    The daily global-mean values of the lower-tropospheric temperature determined from microwave emissions measured by satellites are examined in terms of their signal, noise, and signal-to-noise ratio. Daily and 30-day average noise estimates are reduced by almost 50% and 35%. respectively, by analyzing and adjusting (if necessary) for errors due to 1) missing data, 2) residual harmonics of the annual cycle unique to particular satellites, 3) lack of filtering, and 4) spurious trends. After adjustments, the decadal trend of the lower-tropospheric global temperature from January 1979 through February 1994 becomes -0.058 C. or about 0.03 C per decade cooler than previously calculated.

  15. Reducing Noise in the MSU Daily Lower-Tropospheric Global Temperature Dataset

    NASA Technical Reports Server (NTRS)

    Christy, John R.; Spencer, Roy W.; McNider, Richard T.

    1996-01-01

    The daily global-mean values of the lower-tropospheric temperature determined from microwave emissions measured by satellites are examined in terms of their signal, noise, and signal-to-noise ratio. Daily and 30-day average noise estimates are reduced by almost 50% and 35%. respectively, by analyzing and adjusting (if necessary) for errors due to 1) missing data, 2) residual harmonics of the annual cycle unique to particular satellites, 3) lack of filtering, and 4) spurious trends. After adjustments, the decadal trend of the lower-tropospheric global temperature from January 1979 through February 1994 becomes -0.058 C. or about 0.03 C per decade cooler than previously calculated.

  16. Hyperspectral data analysis procedures with reduced sensitivity to noise

    NASA Technical Reports Server (NTRS)

    Landgrebe, David A.

    1993-01-01

    Multispectral sensor systems have become steadily improved over the years in their ability to deliver increased spectral detail. With the advent of hyperspectral sensors, including imaging spectrometers, this technology is in the process of taking a large leap forward, thus providing the possibility of enabling delivery of much more detailed information. However, this direction of development has drawn even more attention to the matter of noise and other deleterious effects in the data, because reducing the fundamental limitations of spectral detail on information collection raises the limitations presented by noise to even greater importance. Much current effort in remote sensing research is thus being devoted to adjusting the data to mitigate the effects of noise and other deleterious effects. A parallel approach to the problem is to look for analysis approaches and procedures which have reduced sensitivity to such effects. We discuss some of the fundamental principles which define analysis algorithm characteristics providing such reduced sensitivity. One such analysis procedure including an example analysis of a data set is described, illustrating this effect.

  17. A new design of MRPC to reduce noise and crosstalk

    NASA Astrophysics Data System (ADS)

    Weiping, Z.; Yi, W.; Yuanjing, L.; Jianping, C.

    2014-07-01

    The CBM time of flight wall is proposed to be built with MRPC technology. In the past few years we have successfuly improved the rate capability of MRPCs to CBM level. However, in a relative high particle multiplicity situation (over 20 kHz/cm2), multi-hit capability is one of the most demanding requirement of the detector. In a free running mode too many noise not only affect the performance of MRPC but also enlarge the data file or even damage the FIFO. So it is needed to develop low crosstalk and low noise MRPC to meet CBM-TOF requirement. Three strip-readout MRPC with or without shielding grounds were designed to study how to reduce noise and crosstalk of MRPCs. In this paper we report on the performance of three different structures of MRPCs named G-0, G-2 and G-3. Tests with cosmic rays were performed at Tsinghua University. The results show that MRPC G-2 can perform better than other two structures, the average cluster size of G-2 is lower than 1.28 strips and the noise level is below 0.5 Hz/cm2. The detection efficiency is over 98% and the time resolution is around 65 ps.

  18. Reducing antenna mechanical noise in precision spacecraft tracking

    NASA Astrophysics Data System (ADS)

    Armstrong, J. W.; Estabrook, F. B.; Asmar, S. W.; Iess, L.; Tortora, P.

    2008-06-01

    Doppler tracking of deep space probes is central to spacecraft navigation and many radio science investigations. The most sensitive Doppler observations to date were taken using the NASA/JPL Deep Space Network antenna DSS 25 (a 34 m diameter beam-waveguide station instrumented with simultaneous X- and Ka-band uplink and tropospheric scintillation calibration equipment) tracking the Cassini spacecraft. Those observations achieved Doppler fractional frequency stability (Doppler frequency fluctuation divided by center frequency, Δf/fo) ≈ 3 X 10-15 at 1000 s integration time. The leading noise in these very-high-sensitivity tracks was time-dependent unmodeled motion of the ground antenna's phase center (caused, e.g., by antenna sag as elevation angle changes, unmodeled subreflector motion, wind loading, bulk motion of the antenna as it rolled over irregularities in its azimuth ring, etc.). This antenna mechanical noise has seemed irreducible since it is not clear how to build a large, moving, steel structure with intrinsic mechanical stability better than that of current tracking stations. Here we show how intrinsic mechanical noise of a large tracking antenna can be suppressed when two-way Doppler tracking data and receive-only Doppler data from a stiffer antenna are combined with suitable delays. Using this time delay correction procedure, the mechanical noise in the final Doppler observable can be reduced to that of the stiffer antenna. We demonstrate proof-of-concept experimentally and briefly discuss some practical considerations.

  19. Reducing Methyl Halide Emissions from Soils

    NASA Astrophysics Data System (ADS)

    Yates, S. R.; Xuan, R.; Ashworth, D.; Luo, L.

    2011-12-01

    Volatilization and soil transformation are major pathways by which pesticides dissipate from treated agricultural soil. Methyl bromide (MeBr) emissions from agricultural fumigation can lead to depletion of the stratospheric ozone layer. This has led to a gradual phase-out of MeBr and replacement by other halogenated chemicals. However, MeBr continues to be widely used under Critical Use Exemptions and development of emission-reduction strategies remains important. Several methods to reduce emissions of MeBr, and other halogenated soil fumigants, have been developed and are currently being tested under field conditions. In this paper, several approaches for reducing fumigant emissions to the atmosphere are described and include the use of virtually impermeable films, the creation of reactive soil barriers and a recently developed reactive film which was designed to limit loss of MeBr from soil without adding any material to the soil surface. Ammonium thiosulfate (ATS) was used to create a reactive layer. For a reactive soil layer, ATS was sprayed on the soil surface or incorporated to a depth of 1-2 cm. For the reactive film, ATS was placed between two layers of plastic film. The lower plastic layer was a high-density polyethylene film (HDPE), which is readily permeable to MeBr. The upper layer was a virtually impermeable film (VIF) and limits MeBr diffusion. MeBr diffusion and transformation through VIFs and reactive layers were tested in laboratory and field experiments. Although ineffective when dry, when sufficient water was present, reactive barriers substantially depleted halogenated fumigants, including MeBr. When ATS was activated in laboratory experiments, MeBr half-life was about 9.0 h (20C) in a reactive film barrier, and half life decreased with increasing temperature. When the soil was covered with VIF, less than 10% of the added MeBr diffused through the film and the remainder was transformed within the soil. This compares with 60 to 90% emission

  20. Using Perturbation theory to reduce noise in diffusion tensor fields.

    PubMed

    Bansal, Ravi; Staib, Lawrence H; Xu, Dongrong; Laine, Andrew F; Liu, Jun; Peterson, Bradley S

    2009-08-01

    We propose the use of Perturbation theory to reduce noise in Diffusion Tensor (DT) fields. Diffusion Tensor Imaging (DTI) encodes the diffusion of water molecules along different spatial directions in a positive definite, 3 x 3 symmetric tensor. Eigenvectors and eigenvalues of DTs allow the in vivo visualization and quantitative analysis of white matter fiber bundles across the brain. The validity and reliability of these analyses are limited, however, by the low spatial resolution and low Signal-to-Noise Ratio (SNR) in DTI datasets. Our procedures can be applied to improve the validity and reliability of these quantitative analyses by reducing noise in the tensor fields. We model a tensor field as a three-dimensional Markov Random Field and then compute the likelihood and the prior terms of this model using Perturbation theory. The prior term constrains the tensor field to be smooth, whereas the likelihood term constrains the smoothed tensor field to be similar to the original field. Thus, the proposed method generates a smoothed field that is close in structure to the original tensor field. We evaluate the performance of our method both visually and quantitatively using synthetic and real-world datasets. We quantitatively assess the performance of our method by computing the SNR for eigenvalues and the coherence measures for eigenvectors of DTs across tensor fields. In addition, we quantitatively compare the performance of our procedures with the performance of one method that uses a Riemannian distance to compute the similarity between two tensors, and with another method that reduces noise in tensor fields by anisotropically filtering the diffusion weighted images that are used to estimate diffusion tensors. These experiments demonstrate that our method significantly increases the coherence of the eigenvectors and the SNR of the eigenvalues, while simultaneously preserving the fine structure and boundaries between homogeneous regions, in the smoothed tensor

  1. Variability In Motor Learning: Relocating, Channeling and Reducing Noise

    PubMed Central

    Cohen, R.G.; Sternad, D.

    2009-01-01

    Variability in motor performance decreases with practice but is never entirely eliminated, due in part to inherent motor noise. The present study develops a method that quantifies how performers can shape their performance to minimize the effects of motor noise on the result of the movement. Adopting a statistical approach on sets of data, the method quantifies three components of variability (Tolerance, Noise, and Covariation) as costs with respect to optimal performance. T-Cost quantifies how much the result could be improved if the location of the data were optimal, N-Cost compares actual results to results with optimal dispersion at the same location, and C-Cost represents how much improvement stands to be gained if the data covaried optimally. The TNC-Cost analysis is applied to examine the learning of a throwing task that participants practiced for 6 or 15 days. Using a virtual set-up, 15 participants threw a pendular projectile in a simulated concentric force field to hit a target. Two variables, angle and velocity at release, fully determined the projectile’s trajectory and thereby the accuracy of the throw. The task is redundant and the successful solutions define a nonlinear manifold. Analysis of experimental results indicated that all three components were present and that all three decreased across practice. Changes in T-Cost were considerable at the beginning of practice; C-Cost and N-Cost diminished more slowly, with N-Cost remaining the highest. These results showed that performance variability can be reduced by three routes: by tuning tolerance, covariation and noise in execution. We speculate that by exploiting T-Cost and C-Cost, participants minimize the effects of inevitable intrinsic noise. PMID:18953531

  2. Variability in motor learning: relocating, channeling and reducing noise.

    PubMed

    Cohen, R G; Sternad, D

    2009-02-01

    Variability in motor performance decreases with practice but is never entirely eliminated, due in part to inherent motor noise. The present study develops a method that quantifies how performers can shape their performance to minimize the effects of motor noise on the result of the movement. Adopting a statistical approach on sets of data, the method quantifies three components of variability (tolerance, noise, and covariation) as costs with respect to optimal performance. T-Cost quantifies how much the result could be improved if the location of the data were optimal, N-Cost compares actual results to results with optimal dispersion at the same location, and C-Cost represents how much improvement stands to be gained if the data covaried optimally. The TNC-Cost analysis is applied to examine the learning of a throwing task that participants practiced for 6 or 15 days. Using a virtual set-up, 15 participants threw a pendular projectile in a simulated concentric force field to hit a target. Two variables, angle and velocity at release, fully determined the projectile's trajectory and thereby the accuracy of the throw. The task is redundant and the successful solutions define a nonlinear manifold. Analysis of experimental results indicated that all three components were present and that all three decreased across practice. Changes in T-Cost were considerable at the beginning of practice; C-Cost and N-Cost diminished more slowly, with N-Cost remaining the highest. These results showed that performance variability can be reduced by three routes: by tuning tolerance, covariation and noise in execution. We speculate that by exploiting T-Cost and C-Cost, participants minimize the effects of inevitable intrinsic noise.

  3. Noise Characterization and Performance of MODIS Thermal Emissive Bands

    NASA Technical Reports Server (NTRS)

    Madhavan, Sriharsha; Xiong, Xiaoxiong; Wu, Aisheng; Wenny, Brian; Chiang, Kwofu; Chen, Na; Wang, Zhipeng; Li, Yonghong

    2016-01-01

    The MODerate-resolution Imaging Spectroradiometer (MODIS) is a premier Earth-observing sensor of the early 21st century, flying onboard the Terra (T) and Aqua (A) spacecraft. Both instruments far exceeded their six-year design life and continue to operate satisfactorily for more than 15 and 13 years, respectively. The MODIS instrument is designed to make observations at nearly a 100% duty cycle covering the entire Earth in less than two days. The MODIS sensor characteristics include a spectral coverage from 0.41micrometers to 14.4 micrometers, of which those wavelengths ranging from 3.7 micrometers to 14.4 micrometers cover the thermal infrared region which is interspaced in 16 thermal emissive bands (TEBs). Each of the TEB contains ten detectors which record samples at a spatial resolution of 1 km. In order to ensure a high level of accuracy for the TEB-measured top-of-atmosphere radiances, an onboard blackbody (BB) is used as the calibration source. This paper reports the noise characterization and performance of the TEB on various counts. First, the stability of the onboard BB is evaluated to understand the effectiveness of the calibration source. Next, key noise metrics such as the noise equivalent temperature difference and the noise equivalent dn difference (NEdN) for the various TEBs are determined from multiple temperature sources. These sources include the nominally controlled BB temperature of 290 K for T-MODIS and 285 K for A-MODIS, as well as a BB warm up-cool down cycle that is performed over a temperature range from roughly 270 to 315 K. The space-view port that measures the background signal serves as a viable cold temperature source for measuring noise. In addition, a well characterized Earth-view target, the Dome Concordia site located in the Antarctic plateau, is used for characterizing the stability of the sensor, indirectly providing a measure of the NEdN. Based on this rigorous characterization, a list of the noisy and inoperable detectors for

  4. Passive Porous Treatment for Reducing Flap Side-Edge Noise

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan M.; Khorrami, Mehdi R.

    2008-01-01

    A passive porous treatment has been proposed as a means of suppressing noise generated by the airflow around the side edges of partial-span flaps on airplane wings when the flaps are extended in a high-lift configuration. The treatment proposed here does not incur any aerodynamic penalties and could easily be retrofit to existing airplanes. The treatment could also be applied to reduce noise generated by turbomachinery, including wind turbines. Innovative aspects of the proposed treatment include a minimum treatment area and physics-based procedure for treatment design. The efficacy of the treatment was confirmed during wind-tunnel experiments at NASA Ames, wherein the porous treatment was applied to a minute surface area in the vicinity of a flap edge on a 26-percent model of Boeing 777-200 wing.

  5. Method and apparatus for reducing microwave oscillator output noise

    NASA Technical Reports Server (NTRS)

    Dick, G. John (Inventor); Saunders, Jonathan E. (Inventor)

    1991-01-01

    Microwave oscilltors incorporate r.f. feedback with carrier suppression to reduce phase noise. In a direct feedback oscillator arrngement a circulator is interposed between the r.f. amplifier and the high-Q resonator. The amplifier output is applied to the slightly over-coupled input port of the resonator so that the resultant net return signal is the vectorial difference between the signals emitted and reflected from the resonator. The gain of the r.f. amplifier is chosen to regenerate the forward signal from the net return signal. In a STALO-type arrangement, the resonator is critically coupled and an r.f. amplifier added to the path of the net return signal. The sensitivity of the STALO-type feedback loop is thereby enhanced while added amplifier noise is minimized by the superposition of the signals emitted by and reflected from the resonator.

  6. Environment, Renewable Energy and Reduced Carbon Emissions

    NASA Technical Reports Server (NTRS)

    Sen, S.; Khazanov, G.; Kishimoto, Y.

    2011-01-01

    Increased energy security and reduced carbon emissions pose significant challenges for science and technology. However, they also create substantial opportunities for innovative research and development. In this review paper, we highlight some of the key opportunities and mention public policies that are needed to enable the efforts and to maximize the probability of their success. Climate is among the uttermost nonlinear behaviors found around us. As recent studies showed the possible effect of cosmic rays on the Earth's climate, we investigate how complex interactions between the planet and its environment can be responsible for climate anomalies.

  7. Distortion product otoacoustic emission level maps from normal and noise-damaged cochleae.

    PubMed

    Meinke, Deanna K; Clavier, Odile H; Norris, Jesse; Kline-Schoder, Robert; Allen, Lindsay; Buckey, Jay C

    2013-01-01

    Distortion product otoacoustic emission (DPOAE) level mapping may be useful for detecting noise-induced hearing loss (NIHL) early. Employing DPOAE mapping effectively requires knowledge of the optimal mapping parameters to use for detecting noise-induced changes. The goal of this project was to show the map regions that differ most between normal and noise-damaged cochlea to determine the optimal mapping parameters for detecting NIHL. DPOAE level maps were generated for the 2f 1 -f 2 and the 2f 2 -f 1 DPOAEs for 17 normal hearing male subjects and 19 male subjects with NIHL. DPOAEs were measured in DPOAE frequency steps of approximately 44 Hz from 0.5 kHz to 6 kHz using constant f 2 /f 1 ratios incremented in 0.025 steps from 1.025 to 1.5 using both unequal-level (L1,L2 = 65,55 dB sound pressure level (SPL)) and equi-level (L1,L2 = 75,75 dB SPL) stimulus paradigms. Maximal responses for the 2f 2 -f 1 emission at L1,L2 = 65,55 dB SPL were found at lower ratios compared to previous studies. The map regions where NIHL eliminated or reduced DPOAE magnitude were identified. DPOAE level mapping using higher-level, equi-level primaries produced significantly more detectable emissions particularly for the 2f 2 -f 1 emission. The data from this study can be used to optimize DPOAE level mapping parameters for tracking noise-exposed subjects longitudinally.

  8. Evaluation of rosette infrasonic noise-reducing spatial filters.

    PubMed

    Hedlin, Michael A H; Alcoverro, Benoit; D'Spain, Gerald

    2003-10-01

    This paper presents results from recent tests of rosette infrasonic noise-reducing spatial filters at the Pinon Flat Observatory in southern California. Data from 18- and 70-m aperture rosette filters and a reference port are used to gauge the reduction in atmospheric wind-generated noise levels provided by the filters and to examine the effect of these spatial filters on spatially coherent acoustic signals in the 0.02- to 10-Hz band. At wind speeds up to 5.5 m/s, the 18-m rosette filter reduces wind noise levels above 0.2 Hz by 15 to 20 dB. Under the same conditions, the 70-m rosette filter provides noise reduction of up to 15 to 20 dB between 0.02 and 0.7 Hz. Standing wave resonance inside the 70-m filter degrades the reception of acoustic signals above 0.7 Hz. The fundamental mode of the resonance, 15 dB above background, is centered at 2.65-Hz and the first odd harmonic is observed at 7.95 Hz in data from the large filter. Analytical simulations accurately reproduce the noise reduction and resonance observed in the 70-m filter at all wind speeds above 1.25 m/s. Resonance theory indicates that internal reflections that give rise to the resonance observed in the passband are occurring at the summing manifolds, and not at the inlets. Rosette filters are designed for acoustic arrivals with infinite phase velocity. The plane-wave response of the 70-m rosette filter has a strong dependence on frequency above 3.5 Hz at grazing angles of less than 15 degrees from the horizontal. At grazing angles, complete cancellation of the signal occurs at 5 Hz. Theoretical predictions of the phase and amplitude response of 18- and 70-m rosette filters, that take into account internal resonance and time delays between the inlets, compare favorably with observations derived from a cross-spectral analysis of signals from the explosion of a large bolide.

  9. Reducing Antenna Mechanical Noise in Precision Doppler Tracking

    NASA Astrophysics Data System (ADS)

    Armstrong, J. W.; Estabrook, F. B.; Asmar, S. W.; Iess, L.; Tortora, P.

    2006-05-01

    Precision Doppler tracking of deep-space probes is central to spacecraft navigation and many radio science investigations. The most sensitive Doppler observations to date have been taken using the NASA/JPL Deep Space Network (DSN) antenna DSS 25, a 34-m-diameter beam-waveguide station especially instrumented with simultaneous X-band (approximately 8.4-GHz) and Ka-band (approximately 32-GHz) links and tropospheric scintillation calibration equipment, tracking the Cassini spacecraft. These Cassini observations achieved Doppler fractional frequency stability (Doppler frequency fluctuation divided by center frequency, Delta f / f_o ) of approximately 3 x 10^-15 at tau = 1000 s integration. In those very-high-sensitivity tracks, the leading disturbance was antenna mechanical noise: time-dependent unmodeled physical motion of the ground antenna's phase center caused by antenna sag as the elevation angle changed, unmodeled subreflector motion, wind loading, bulk motion of the antenna as it rolled over irregularities in the supporting azimuth ring, differential thermal expansion of the structure, etc. This noise has seemed irreducible at reasonable cost, since it is unclear how to build a practical, large, moving, steel structure having mechanical stability significantly better than that of current tracking stations. Here we show how the mechanical noise of a large tracking antenna can effectively be removed when two-way Doppler tracking data from an existing DSN antenna are suitably combined with simultaneous tracking data using an ancillary (smaller and stiffer) antenna. Using our method, the mechanical noise in the final Doppler observable can be reduced, substantially, to that of the stiffer antenna.

  10. Rotor blade system with reduced blade-vortex interaction noise

    NASA Technical Reports Server (NTRS)

    Leishman, John G. (Inventor); Han, Yong Oun (Inventor)

    2005-01-01

    A rotor blade system with reduced blade-vortex interaction noise includes a plurality of tube members embedded in proximity to a tip of each rotor blade. The inlets of the tube members are arrayed at the leading edge of the blade slightly above the chord plane, while the outlets are arrayed at the blade tip face. Such a design rapidly diffuses the vorticity contained within the concentrated tip vortex because of enhanced flow mixing in the inner core, which prevents the development of a laminar core region.

  11. Equatorial Noise Emissions and Their Quasi-Periodic Modulation

    NASA Astrophysics Data System (ADS)

    Nemec, F.; Santolik, O.; Hrbackova, Z.; Pickett, J. S.; Cornilleau-Wehrlin, N.; Parrot, M.; Hayosh, M.

    2015-12-01

    Equatorial noise (EN) emissions are electromagnetic waves at frequencies between the proton cyclotron frequency and the lower hybrid frequency routinely observed in the equatorial region of the inner magnetosphere. They propagate in the extraordinary mode nearly perpendicular to the ambient magnetic field, and they exhibit a harmonic structure related to the ion cyclotron frequency in the source region. We analyze more than 2000 EN events observed by the wave instruments on board the Cluster spacecraft, and we find that about 5% of EN events are not continuous in time, but exhibit a quasi-periodic (QP) modulation of the wave intensity. Typical modulation periods are on the order of minutes. The events predominantly occur in the noon-to-dawn local time sector, and their occurrence is related to the periods of increased geomagnetic activity and higher solar wind speeds. We suggest that the QP modulation of EN events may be due to compressional ULF pulsations, which periodically modulate the wave growth in the source region. These compressional ULF pulsations were identified in about half of the events. Finally, we demonstrate that EN emissions with QP modulation of the wave intensity can propagate down to altitudes as low as 700 km.

  12. Reducing hospital noise: a review of medical device alarm management.

    PubMed

    Konkani, Avinash; Oakley, Barbara; Bauld, Thomas J

    2012-01-01

    Increasing noise in hospital environments, especially in intensive care units (ICUs) and operating rooms (ORs), has created a formidable challenge for both patients and hospital staff. A major contributing factor for the increasing noise levels in these environments is the number of false alarms generated by medical devices. This study focuses on discovering best practices for reducing the number of false clinical alarms in order to increase patient safety and provide a quiet environment for both work and healing. The researchers reviewed Pub Med, Web of Knowledge and Google Scholar sources to obtain original journal research and review articles published through January 2012. This review includes 27 critically important journal articles that address different aspects of medical device alarms management, including the audibility, identification, urgency mapping, and response time of nursing staff and different solutions to such problems. With current technology, the easiest and most direct method for reducing false alarms is to individualize alarm settings for each patient's condition. Promoting an institutional culture change that emphasizes the importance of individualization of alarms is therefore an important goal. Future research should also focus on the development of smart alarms.

  13. Effects of ascorbic acid on oxidative system and transient evoked otoacoustic emissions in rabbits exposed to noise.

    PubMed

    Dereköy, Fevzi Sefa; Köken, Tülay; Yilmaz, Deniz; Kahraman, Ahmet; Altuntaş, Ali

    2004-10-01

    The objective was to investigate the effects of both noise exposure and ascorbic acid on oxidative status and hearing thresholds of rabbits. Randomized prospective animal study comparing oxidative parameters and otoacoustic emissions in two rabbit groups exposed to noise. One group was given ascorbic acid, the other group was not given any treatment. Two groups of rabbits were used in the study; each group had six rabbits. The six rabbits in the first group were not given any treatment, whereas 500 mg intramuscular ascorbic acid twice daily for 2 1/2 days was given to the six rabbits in the second group. Transient evoked otoacoustic emissions were recorded in all animals before and after noise exposure. Total protein sulfhydryl groups, carbonyl contents, and malondialdehyde levels, as well as erythrocyte glutathione, superoxide dismutase, and catalase enzyme levels, were measured in all rabbits. All the rabbits were exposed to noise (100 dB sound pressure level, 1000 Hz, 1 h), and transient evoked otoacoustic emissions were recorded again. When oxidative parameters before noise exposure were compared, erythrocyte glutathione and catalase enzyme levels were detected to be higher in the second group (P <.05). In the first group of rabbits after noise exposure, total protein sulfhydryl groups were found to be reduced (P <.05), whereas plasma carbonyl contents and malondialdehyde levels were elevated significantly (P <.05). In this group, erythrocyte glutathione, superoxide dismutase, and catalase enzyme levels were low (P <.05). In the second group, which was given ascorbic acid, total protein sulfhydryl groups were reduced (P <.05), whereas plasma carbonyl contents and malondialdehyde levels did not change (P >.05) following noise exposure. In the second group, erythrocyte glutathione and catalase enzyme levels were reduced (P <.05), but superoxide dismutase levels did not change (P >.05). Transient evoked otoacoustic emissions after noise exposure were weak in both

  14. Reducing VOC Press Emission from OSB Manufacturing

    SciTech Connect

    Dr. Gary D. McGinnis; Laura S. WIlliams; Amy E. Monte; Jagdish Rughani: Brett A. Niemi; Thomas M. Flicker

    2001-12-31

    Current regulations require industry to meet air emission standards with regard to particulates, volatile organic compounds (VOCs), hazardous air pollutants (HAPs) and other gases. One of many industries that will be affected by the new regulations is the wood composites industry. This industry generates VOCs, HAPs, and particulates mainly during the drying and pressing of wood. Current air treatment technologies for the industry are expensive to install and operate. As regulations become more stringent, treatment technologies will need to become more efficient and cost effective. The overall objective of this study is to evaluate the use of process conditions and chemical additives to reduce VOC/HAPs in air emitted from presses and dryers during the production of oriented strand board.

  15. Characteristics of noise-canceling headphones to reduce the hearing hazard for MP3 users.

    PubMed

    Liang, Maojin; Zhao, Fei; French, David; Zheng, Yiqing

    2012-06-01

    Three pairs of headphones [standard iPod ear buds and two noise-canceling headphones (NCHs)] were chosen to investigate frequency characteristics of noise reduction, together with their attenuation effects on preferred listening levels (PLLs) in the presence of various types of background noise. Twenty-six subjects with normal hearing chose their PLLs in quiet, street noise, and subway noise using the three headphones and with the noise-canceling system on/off. Both sets of NCHs reduced noise levels at mid- and high-frequencies. Further noise reductions occurred in low frequencies with the noise canceling system switched on. In street noise, both NCHs had similar noise reduction effects. In subway noise, better noise reduction effects were found in the expensive NCH and with noise-canceling on. A two way repeated measures analysis of variance showed that both listening conditions and headphone styles were significant influencing factors on the PLLs. Subjects tended to increase their PLLs as the background noise level increased. Compared with ear buds, PLLs obtained from NCHs-on in the presence of background noise were reduced up to 4 dB. Therefore, proper selection and use of NCHs appears beneficial in reducing the risk of hearing damage caused by high music listening levels in the presence of background noise.

  16. Impedance control reduces instability that arises from motor noise.

    PubMed

    Selen, Luc P J; Franklin, David W; Wolpert, Daniel M

    2009-10-07

    There is ample evidence that humans are able to control the endpoint impedance of their arms in response to active destabilizing force fields. However, such fields are uncommon in daily life. Here, we examine whether the CNS selectively controls the endpoint impedance of the arm in the absence of active force fields but in the presence of instability arising from task geometry and signal-dependent noise (SDN) in the neuromuscular system. Subjects were required to generate forces, in two orthogonal directions, onto four differently curved rigid objects simulated by a robotic manipulandum. The endpoint stiffness of the limb was estimated for each object curvature. With increasing curvature, the endpoint stiffness increased mainly parallel to the object surface and to a lesser extent in the orthogonal direction. Therefore, the orientation of the stiffness ellipses did not orient to the direction of instability. Simulations showed that the observed stiffness geometries and their pattern of change with instability are the result of a tradeoff between maximizing the mechanical stability and minimizing the destabilizing effects of SDN. Therefore, it would have been suboptimal to align the stiffness ellipse in the direction of instability. The time course of the changes in stiffness geometry suggests that modulation takes place both within and across trials. Our results show that an increase in stiffness relative to the increase in noise can be sufficient to reduce kinematic variability, thereby allowing stiffness control to improve stability in natural tasks.

  17. Using Kalman filters to reduce noise from RFID location system.

    PubMed

    Abreu, Pedro Henriques; Xavier, José; Silva, Daniel Castro; Reis, Luís Paulo; Petry, Marcelo

    2014-01-01

    Nowadays, there are many technologies that support location systems involving intrusive and nonintrusive equipment and also varying in terms of precision, range, and cost. However, the developers some time neglect the noise introduced by these systems, which prevents these systems from reaching their full potential. Focused on this problem, in this research work a comparison study between three different filters was performed in order to reduce the noise introduced by a location system based on RFID UWB technology with an associated error of approximately 18 cm. To achieve this goal, a set of experiments was devised and executed using a miniature train moving at constant velocity in a scenario with two distinct shapes-linear and oval. Also, this train was equipped with a varying number of active tags. The obtained results proved that the Kalman Filter achieved better results when compared to the other two filters. Also, this filter increases the performance of the location system by 15% and 12% for the linear and oval paths respectively, when using one tag. For a multiple tags and oval shape similar results were obtained (11-13% of improvement).

  18. Shaping and timing gradient pulses to reduce MRI acoustic noise.

    PubMed

    Segbers, Marcel; Rizzo Sierra, Carlos V; Duifhuis, Hendrikus; Hoogduin, Johannes M

    2010-08-01

    A method to reduce the acoustic noise generated by gradient systems in MRI has been recently proposed; such a method is based on the linear response theory. Since the physical cause of MRI acoustic noise is the time derivative of the gradient current, a common trapezoid current shape produces an acoustic gradient coil response mainly during the rising and falling edge. In the falling edge, the coil acoustic response presents a 180 degrees phase difference compared to the rising edge. Therefore, by varying the width of the trapezoid and keeping the ramps constant, it is possible to suppress one selected frequency and its higher harmonics. This value is matched to one of the prominent resonance frequencies of the gradient coil system. The idea of cancelling a single frequency is extended to a second frequency, using two successive trapezoid-shaped pulses presented at a selected interval. Overall sound pressure level reduction of 6 and 10 dB is found for the two trapezoid shapes and a single pulse shape, respectively. The acoustically optimized pulse shape proposed is additionally tested in a simulated echo planar imaging readout train, obtaining a sound pressure level reduction of 12 dB for the best case.

  19. Using Kalman Filters to Reduce Noise from RFID Location System

    PubMed Central

    Xavier, José; Reis, Luís Paulo; Petry, Marcelo

    2014-01-01

    Nowadays, there are many technologies that support location systems involving intrusive and nonintrusive equipment and also varying in terms of precision, range, and cost. However, the developers some time neglect the noise introduced by these systems, which prevents these systems from reaching their full potential. Focused on this problem, in this research work a comparison study between three different filters was performed in order to reduce the noise introduced by a location system based on RFID UWB technology with an associated error of approximately 18 cm. To achieve this goal, a set of experiments was devised and executed using a miniature train moving at constant velocity in a scenario with two distinct shapes—linear and oval. Also, this train was equipped with a varying number of active tags. The obtained results proved that the Kalman Filter achieved better results when compared to the other two filters. Also, this filter increases the performance of the location system by 15% and 12% for the linear and oval paths respectively, when using one tag. For a multiple tags and oval shape similar results were obtained (11–13% of improvement). PMID:24592186

  20. Reducing environmental noise impacts: A USAREUR noise-management program handbook. Final report

    SciTech Connect

    Feather, T.D.; Shekell, T.K.

    1991-06-01

    Noise pollution is a major environmental problem faced by the U.S. Army in Europe. Noise-related complaints from German citizens can escalate into intense political issues in German communities. This in turn hampers efficient operation of military training and often times threatens the Army's mission. In order to remedy these problems, USAREUR has developed a noise management program. A successful noise management program will limit the impact of unavoidable noise on the populace. This report, a component of the noise management program, is a reference document for noise management planning. It contains guidelines and rules-of-thumb for noise management. This document contains procedures which operation and training level personnel can understand and apply in their day to day noise management planning. Noise mitigation tips are given. Basic technical information that will aid in understanding noise mitigation is provided along with noise management through land use planning. Noise management for specific components of the military community, (airfields, base operations, training areas, and housing and recreation areas) are addressed. The nature of noise generated, means of noise abatement at the source, path, and receiver (both physical and organizational/public relations methods), and a case study example are described.

  1. Nitrogen management to reduce nitrous oxide emissions

    USDA-ARS?s Scientific Manuscript database

    Nitrous oxide (N2O) emissions from agricultural soils represent a complex interaction between the inputs of nitrogen into the soil and the soil environment. Mitigating these emissions will have a positive impact on greenhouse gases. Agriculture is the primary source of N2O emissions and must develop...

  2. Reduced Perceived Noise Low Tip Speed Fans as a Result of Abandoning Cutoff Stator Vane Numbers

    NASA Technical Reports Server (NTRS)

    Dittmar, James

    1998-01-01

    As fan tip speeds are reduced, broadband noise is becoming more important in the calculation of perceived noise. Past experience indicates that lower vane number stators with either constant chord or constant solidity may be a way to reduce broadband noise caused by the interaction of the rotor wake turbulence with the stators. A baseline fan and a low blade number fan were investigated to determine if a noise reduction was possible. The low vane number fan showed a 2 PndB and a 1.5 PNLT noise reduction. These reductions show that this is a viable technique for reducing the perceived noise of low tip speed fans.

  3. Apparatus and method for reducing vehicular fuel pump noise

    SciTech Connect

    Nashif, A.D.

    1991-06-04

    This paper describes a vehicular fuel pump system including a fuel pump and at least one fuel line mounted inside a fuel tank, noise reduction means. It comprises: a passive vibrator mounted inside the tank to the line, at a position on the line at which the line vibrates at substantially its maximum amplitude, the vibrator comprising spring means mounting a weight to the line, the vibrator having a mass and the spring means having stiffness and damping values selected to cause the vibrator to vibrate resonantly when the line vibrates, out of phase with respect to the vibration of the line and at an amplitude of sufficient magnitude to at least partially reduce the vibration of the line, the vibrator being connected to the pump and tank only through the line.

  4. Resonant-cavity light-emitting diodes: quantum noise and spatial emission characteristics

    NASA Astrophysics Data System (ADS)

    Birkner, R. H.; Kaiser, J.; Elsässer, W.; Jung, C.

    2004-12-01

    We demonstrate the interplay between the intensity noise and the spatial emission characteristics of resonant-cavity light-emitting diodes. First, we find that the total aperture intensity noise exhibits a sub-shot noise behavior in a quite large pumping regime. Second, we investigate the angular, spectral, and spatial emission characteristics of the devices by controlling the shape and width of the angular intensity distribution via temperature detuning of the quantum well wavelength and the cavity resonance wavelength. Finally, the angular and aperture resolved intensity noise exhibit a super-shot noise behavior in contrast to that of the total emission. We explain this difference with anticorrelations between various radial components which increase with the temperature-tuned extension of the spatial emission.

  5. Effect of broadband and narrowband contralateral noise on psychophysical tuning curves and otoacoustic emissions.

    PubMed

    Wicher, Andrzej; Moore, Brian C J

    2014-05-01

    The relative effectiveness of narrowband and broadband noises in activating the efferent system was assessed by comparing the effect of contralateral stimulation (CS) with such sounds on psychophysical tuning curves (PTCs) determined in simultaneous masking, using signal frequencies of 1000 or 2000 Hz. To check that the CS stimuli used did activate the efferent system, distortion product otoacoustic emissions (DPOAEs) were also measured in the absence and presence of narrowband and broadband CS. The CS had no consistent effect on the masker level at the tips of the PTCs. A broadband pink noise CS consistently reduced the masker level required for threshold on both the low- and high-frequency sides of the PTCs for the 2000-Hz signal frequency. However, there were no consistent effects of the CS for any other case. The broadband pink noise CS had a greater effect in reducing DPOAE levels than the narrowband CS. The results provide psychophysical evidence supporting the idea that the efferent system is activated more effectively by a broadband than by a narrowband CS, at least for a signal frequency of 2000 Hz.

  6. On strategies for reducing greenhouse gas emissions.

    PubMed

    Bolin, B; Kheshgi, H S

    2001-04-24

    Equity is of fundamental concern in the quest for international cooperation to stabilize greenhouse gas concentrations by the reduction of emissions. By modeling the carbon cycle, we estimate the global CO(2) emissions that would be required to stabilize the atmospheric concentration of CO(2) at levels ranging from 450 to 1,000 ppm. These are compared, on both an absolute and a per-capita basis, to scenarios for emissions from the developed and developing worlds generated by socio-economic models under the assumption that actions to mitigate greenhouse gas emissions are not taken. Need and equity have provided strong arguments for developing countries to request that the developed world takes the lead in controlling its emissions, while permitting the developing countries in the meantime to use primarily fossil fuels for their development. Even with major and early control of CO(2) emissions by the developed world, limiting concentration to 450 ppm implies that the developing world also would need to control its emissions within decades, given that we expect developing world emissions would otherwise double over this time. Scenarios leading to CO(2) concentrations of 550 ppm exhibit a reduction of the developed world's per-capita emission by about 50% over the next 50 years. Even for the higher stabilization levels considered, the developing world would not be able to use fossil fuels for their development in the manner that the developed world has used them.

  7. On strategies for reducing greenhouse gas emissions

    PubMed Central

    Bolin, Bert; Kheshgi, Haroon S.

    2001-01-01

    Equity is of fundamental concern in the quest for international cooperation to stabilize greenhouse gas concentrations by the reduction of emissions. By modeling the carbon cycle, we estimate the global CO2 emissions that would be required to stabilize the atmospheric concentration of CO2 at levels ranging from 450 to 1,000 ppm. These are compared, on both an absolute and a per-capita basis, to scenarios for emissions from the developed and developing worlds generated by socio-economic models under the assumption that actions to mitigate greenhouse gas emissions are not taken. Need and equity have provided strong arguments for developing countries to request that the developed world takes the lead in controlling its emissions, while permitting the developing countries in the meantime to use primarily fossil fuels for their development. Even with major and early control of CO2 emissions by the developed world, limiting concentration to 450 ppm implies that the developing world also would need to control its emissions within decades, given that we expect developing world emissions would otherwise double over this time. Scenarios leading to CO2 concentrations of 550 ppm exhibit a reduction of the developed world's per-capita emission by about 50% over the next 50 years. Even for the higher stabilization levels considered, the developing world would not be able to use fossil fuels for their development in the manner that the developed world has used them. PMID:11296250

  8. Quantum-noise quenching in the correlated spontaneous-emission laser as a multiplicative noise process. II. Rigorous analysis including amplitude noise

    SciTech Connect

    Schleich, W.; Scully, M.O.; von Garssen, H.

    1988-04-15

    An analytical steady-state distribution for the phase difference psi in a correlated spontaneous-emission laser (CEL) is derived based on the amplitude and phase equations of a CEL. This distribution is shown to be an excellent approximation to that obtained from a numerical simulation of the complete set of CEL equations. In particular, the effects of amplitude noise on CEL operation are considered and it is shown that fluctuations in the relative amplitude are also noise quenched.

  9. Characterization and Impact of Low Frequency Wind Turbine Noise Emissions

    NASA Astrophysics Data System (ADS)

    Finch, James

    Wind turbine noise is a complex issue that requires due diligence to minimize any potential impact on quality of life. This study enhances existing knowledge of wind turbine noise through focused analyses of downwind sound propagation, directionality, and the low frequency component of the noise. Measurements were conducted at four wind speeds according to a design of experiments at incremental distances and angles. Wind turbine noise is shown to be highly directional, while downwind sound propagation is spherical with limited ground absorption. The noise is found to have a significant low frequency component that is largely independent of wind speed over the 20-250 Hz range. The generated low frequency noise is shown to be audible above 40 Hz at the MOE setback distance of 550 m. Infrasound levels exhibit higher dependency on wind speed, but remain below audible levels up to 15 m/s.

  10. An effective, economical method of reducing environmental noise in the vivarium.

    PubMed

    Young, Maggie T; French, Alan L; Clymer, Jeffrey W

    2011-07-01

    High levels of ambient noise can have detrimental effects on laboratory animal wellbeing and may affect experimental results. In addition, excessive noise can reduce technician comfort and performance. This study was performed to determine whether inexpensive, passive acoustic noise abatement measures could meaningfully reduce noise levels. Sound level measurements for various activities were obtained in the incoming processing room for pigs before and after installing gypsum acoustic paneling, covering metal-to-metal contact points with strips of adhesive-backed rubber, and replacing hard plastic wheels on transport carts with neoprene wheels. The modifications reduced the overall average noise level by 8.1 dB. Average noise levels for each activity were all less than 85 dB after the modifications. Average noise levels can be reduced effectively and economically with passive abatement methods. Intermittent spikes in noise are more difficult to control and may require attention to the individual activity.

  11. An Effective, Economical Method of Reducing Environmental Noise in the Vivarium

    PubMed Central

    Young, Maggie T; French, Alan L; Clymer, Jeffrey W

    2011-01-01

    High levels of ambient noise can have detrimental effects on laboratory animal wellbeing and may affect experimental results. In addition, excessive noise can reduce technician comfort and performance. This study was performed to determine whether inexpensive, passive acoustic noise abatement measures could meaningfully reduce noise levels. Sound level measurements for various activities were obtained in the incoming processing room for pigs before and after installing gypsum acoustic paneling, covering metal-to-metal contact points with strips of adhesive-backed rubber, and replacing hard plastic wheels on transport carts with neoprene wheels. The modifications reduced the overall average noise level by 8.1 dB. Average noise levels for each activity were all less than 85 dB after the modifications. Average noise levels can be reduced effectively and economically with passive abatement methods. Intermittent spikes in noise are more difficult to control and may require attention to the individual activity. PMID:21838981

  12. Optimization Model for Reducing Emissions of Greenhouse ...

    EPA Pesticide Factsheets

    The EPA Vehicle Greenhouse Gas (VGHG) model is used to apply various technologies to a defined set of vehicles in order to meet a specified GHG emission target, and to then calculate the costs and benefits of doing so. To facilitate its analysis of the costs and benefits of the control of GHG emissions from cars and trucks.

  13. Techniques for Reducing Gun Blast Noise Levels: An Experimental Study

    DTIC Science & Technology

    1981-04-01

    gun muzzle blast noise level were in- vestigated experimentally to determine potential effectiveness and utility for existing major-caliber guns...impact on training and testing operations was to be minimized. Most of the noise reduction techniques that were investigated involve the use of some type ...shock noise level at the earth’s surface varies according to a complicated dependence upon projectile trajectory, projectile speed along the trajectory

  14. Instrument Variables for Reducing Noise in Parallel MRI Reconstruction

    PubMed Central

    Lin, Hong

    2017-01-01

    Generalized autocalibrating partially parallel acquisition (GRAPPA) has been a widely used parallel MRI technique. However, noise deteriorates the reconstructed image when reduction factor increases or even at low reduction factor for some noisy datasets. Noise, initially generated from scanner, propagates noise-related errors during fitting and interpolation procedures of GRAPPA to distort the final reconstructed image quality. The basic idea we proposed to improve GRAPPA is to remove noise from a system identification perspective. In this paper, we first analyze the GRAPPA noise problem from a noisy input-output system perspective; then, a new framework based on errors-in-variables (EIV) model is developed for analyzing noise generation mechanism in GRAPPA and designing a concrete method—instrument variables (IV) GRAPPA to remove noise. The proposed EIV framework provides possibilities that noiseless GRAPPA reconstruction could be achieved by existing methods that solve EIV problem other than IV method. Experimental results show that the proposed reconstruction algorithm can better remove the noise compared to the conventional GRAPPA, as validated with both of phantom and in vivo brain data. PMID:28197419

  15. Multi-images deconvolution improves signal-to-noise ratio on gated stimulated emission depletion microscopy

    SciTech Connect

    Castello, Marco; Diaspro, Alberto; Vicidomini, Giuseppe

    2014-12-08

    Time-gated detection, namely, only collecting the fluorescence photons after a time-delay from the excitation events, reduces complexity, cost, and illumination intensity of a stimulated emission depletion (STED) microscope. In the gated continuous-wave- (CW-) STED implementation, the spatial resolution improves with increased time-delay, but the signal-to-noise ratio (SNR) reduces. Thus, in sub-optimal conditions, such as a low photon-budget regime, the SNR reduction can cancel-out the expected gain in resolution. Here, we propose a method which does not discard photons, but instead collects all the photons in different time-gates and recombines them through a multi-image deconvolution. Our results, obtained on simulated and experimental data, show that the SNR of the restored image improves relative to the gated image, thereby improving the effective resolution.

  16. Noise-color-induced quenching of fluctuations in a correlated spontaneous-emission laser model

    SciTech Connect

    Habiger, R.G.K.; Risken, H. ); James, M.; Moss, F. ); Schleich, W. Center for Advanced Studies and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 )

    1990-04-01

    We show via (1) an approximate, analytical technique, (2) a formally exact matrix continued-fraction analysis, and (3) an analog simulation of the classical Langevin equation of a correlated spontaneous-emission laser (CEL) that noise of nonzero correlation time leads to an enhancement of the characteristic CEL noise quenching.

  17. Noise Levels during Aerobics and the Potential Effects on Distortion Product Otoacoustic Emissions

    ERIC Educational Resources Information Center

    Torre, Peter, III; Howell, Jennifer C.

    2008-01-01

    The purpose of this study was to measure noise levels during aerobics classes and to examine how outer hair cell (OHC) function, using distortion product otoacoustic emissions (DPOAEs), may be affected by this exposure. Fifty individuals (48 women and 2 men, ages 19-41 years) participated in 50-min aerobics classes. Noise levels were measured…

  18. Relation between metric and decametric noise storm sources and microwave S-component emissions

    NASA Technical Reports Server (NTRS)

    Sakurai, K.

    1974-01-01

    Various activities are reported by taking into account the properties of the active region and its relationship to low frequency burst emissions observed by the IMP-6 satellite. The relation of metric noise continuum storms (200 MHz) with the S-component of microwave emissions (2800 MHz) are examined. Taking the results analyzed, a model on the growth of radio noise continuum sources in metric and decametric frequencies and its relation to microwave and other solar active phenomena are considered.

  19. Auditory white noise reduces postural fluctuations even in the absence of vision.

    PubMed

    Ross, Jessica Marie; Balasubramaniam, Ramesh

    2015-08-01

    The contributions of somatosensory, vestibular, and visual feedback to balance control are well documented, but the influence of auditory information, especially acoustic noise, on balance is less clear. Because somatosensory noise has been shown to reduce postural sway, we hypothesized that noise from the auditory modality might have a similar effect. Given that the nervous system uses noise to optimize signal transfer, adding mechanical or auditory noise should lead to increased feedback about sensory frames of reference used in balance control. In the present experiment, postural sway was analyzed in healthy young adults where they were presented with continuous white noise, in the presence and absence of visual information. Our results show reduced postural sway variability (as indexed by the body's center of pressure) in the presence of auditory noise, even when visual information was not present. Nonlinear time series analysis revealed that auditory noise has an additive effect, independent of vision, on postural stability. Further analysis revealed that auditory noise reduced postural sway variability in both low- and high-frequency regimes (> or <0.3 Hz) of sway, suggesting that both spontaneous and feedback-driven aspects of postural fluctuations were influenced by acoustic noise. Our results support the idea that auditory white noise reduces postural sway, suggesting that auditory noise might be used for therapeutic and rehabilitation purposes in older individuals and those with balance disorders.

  20. Reducing noise by repetition: introduction to signal averaging

    NASA Astrophysics Data System (ADS)

    Hassan, Umer; Sabieh Anwar, Muhammad

    2010-05-01

    This paper describes theory and experiments, taken from biophysics and physiological measurements, to illustrate the technique of signal averaging. In the process, students are introduced to the basic concepts of signal processing, such as digital filtering, Fourier transformation, baseline correction, pink and Gaussian noise, and the cross- and autocorrelation functions. From these computations, the students estimate physically interesting parameters such as the pulse rate and blood flow velocity. They also learn about some of the pitfalls encountered in quantifying the signal and noise components for a meaningful computation of the signal-to-noise ratio.

  1. The environmental cost of reducing agricultural fine particulate matter emissions.

    PubMed

    Funk, Paul A

    2010-06-01

    The U.S. Environmental Protection Agency (EPA) revised the National Ambient Air Quality Standards (NAAQS) in 2006, reducing acceptable fine particulate matter (PM2.5) levels; state environmental protection agencies in states with nonattainment areas are required to draft State Implementation Plans (SIPs) detailing measures to reduce regional PM2.5 levels by reducing PM2.5 and PM2.5 precursor emissions. These plans need to account for increases in emissions caused by operating control technologies. Potential PM2.5 emissions reductions realized by adding a second set of dust cyclones were estimated for the cotton ginning industry. Increases in energy consumption were calculated based on dust cyclone air pressure drop. Additional energy required was translated into increased emissions using published emission factors and state emissions inventories. Reductions in gin emissions were compared with increases in emissions at the power plant. Because of the electrical energy required, reducing one unit of agricultural PM2.5 emissions at a cotton gin results in emitting 0.11-2.67 units of direct PM2.5, 1.39-69.1 units of PM2.5 precursors, 1.70-76.8 units of criteria pollutants, and 692-15,400 units of greenhouse gases at the point where electricity is produced. If regulations designed to reduce rural PM2.5 emissions increase electrical power consumption, the unintended net effect may be more emissions, increased environmental damage, and a greater risk to public health.

  2. Reducing the overhead for quantum computation when noise is biased

    NASA Astrophysics Data System (ADS)

    Webster, Paul; Bartlett, Stephen D.; Poulin, David

    2015-12-01

    We analyze a model for fault-tolerant quantum computation with low overhead suitable for situations where the noise is biased. The basis for this scheme is a gadget for the fault-tolerant preparation of magic states that enable universal fault-tolerant quantum computation using only Clifford gates that preserve the noise bias. We analyze the distillation of |T > -type magic states using this gadget at the physical level, followed by concatenation with the 15-qubit quantum Reed-Muller code, and comparing our results with standard constructions. In the regime where the noise bias (rate of Pauli Z errors relative to other single-qubit errors) is greater than a factor of 10, our scheme has lower overhead across a broad range of relevant noise rates.

  3. Sound-Level Measurements of a Light Airplane Modified to Reduce Noise Reaching the Ground

    NASA Technical Reports Server (NTRS)

    Vogeley, A W

    1949-01-01

    An Army liaison-type airplane, representative of personal airplanes in the 150 to 200 horsepower class, has been modified to reduce propeller and engine noise according to known principles of airplane-noise reduction. Noise-level measurements demonstrate that, with reference to an observer on the ground, a noisy airplane of this class can be made quiet -- perhaps more quiet than necessary. In order to avoid extreme and unnecessary modifications, acceptable noise levels must be determined.

  4. REDUCING STYRENE EMISSIONS FROM SPRAYED FILLED RESINS

    EPA Science Inventory

    Styrene emissions are coming under increasing study as the U.S. Environmental Protection Agency (EPA) develops maximum achievable control technology standards. During the manufacture of fiber-reinforced plastics/composites products, styrene, a volatile organic compound and a haz...

  5. REDUCING STYRENE EMISSIONS FROM SPRAYED FILLED RESINS

    EPA Science Inventory

    Styrene emissions are coming under increasing study as the U.S. Environmental Protection Agency (EPA) develops maximum achievable control technology standards. During the manufacture of fiber-reinforced plastics/composites products, styrene, a volatile organic compound and a haz...

  6. Effects of background noise on audiometric thresholds during positron emission tomography: passive and active noise-reduction.

    PubMed

    Kim, K; Burkard, R F; Lockwood, A H; Salvi, R J

    2000-01-01

    Position emission tomography (PET) is used to assess the functional activity of the human auditory brain; however, the activity detected by PET could be affected by ambient acoustic noise from the PET equipment. To evaluate these effects, we compared behavioural thresholds in the PET camera with those measured in an audiometric sound booth. Thresholds were measured with: (i) ER2 earphones, (ii) ER2 earphones + Cabot earmuffs, (iii) ER2 earphones + Bose Series II Aviation Headset with active noise-reduction off, and (iv) ER2 earphones + Bose Series II Aviation Headset with active noise-reduction on. Overall ambient noise level in the camera was 73 dB SPL and the maximum octave-band SPL was 68 dB SPL at 250 Hz. Threshold elevations in the PET camera were greatest with ER2 (17 dB, 125 Hz) earphones and lowest with ER2 earphones + Bose Series II Aviation Headset (8 dB at 250 Hz) with active noise-reduction. Thus, PET scanner noise had little or no effect on threshold when stimuli were presented through ER2 earphones covered with an activated Bose Series II Aviation Headset.

  7. [Distortion product otoacoustic emissions before and after one year exposure to impulse noise].

    PubMed

    Konopka, Wiesław; Olszewski, Jurek; Pietkiewicz, Piotr; Mielczarek, Marzena

    2006-01-01

    Firearms are a common source of impulse noise that may be very harmful to the auditory organ. Impulse noise from weapons and explosions continually produces hearing damage among military personnel. The discovery of otoacoustic emission (OAE) has given a new possibility of early diagnosis of noise induced hearing loss. The transiently evoked otoacoustic emission (TEOAE) and distortion product otoacoustic emission (DPOAE) are non-invasive, objective and frequency specific audiometric tests for evaluating outer hair cell function. The aim of the study was to asses the effects of exposure to impulse noise on DPOAE after one year of the obligatory military service. The study comprised 92 (184 ears) soldiers, subjected to impulse noise during military service. The examine group was divided according total noise exposure. The control group consisted of secondary school students not exposed to noise. DPOAE was recorded before and after one year of military service. After military service significant deterioration of DPOAE level was observed at frequencies of 1, 3, and 4 kHz on the right ear and 2, 5 and 6 kHz left one. 1. Reduction of DPOAE amplitude connected all frequencies. 2. We did not notice significant differences between groups connected total noise exposure.

  8. Reducing Carbon Dioxide Emissions: Using the Mole Concept.

    ERIC Educational Resources Information Center

    Myers, Alan

    2002-01-01

    Provides an application of quantitative chemistry concepts in the context of motor vehicle emissions. Shows how carbon dioxide emissions from cars may be reduced by up to 25% by reducing motorway speeds from 70-75 mph to 60 mph. (Author/MM)

  9. Reducing Carbon Dioxide Emissions: Using the Mole Concept.

    ERIC Educational Resources Information Center

    Myers, Alan

    2002-01-01

    Provides an application of quantitative chemistry concepts in the context of motor vehicle emissions. Shows how carbon dioxide emissions from cars may be reduced by up to 25% by reducing motorway speeds from 70-75 mph to 60 mph. (Author/MM)

  10. Communicating airport noise emission data to the general public.

    PubMed

    Gasco, Luis; Asensio, Cesar; de Arcas, Guillermo

    2017-05-15

    Despite the efforts that the aviation industry has undertaken during the last few decades, noise annoyance remains high, partly because of the continuous transport demands of modern societies and partly because of changes in citizen expectations and their growing environmental concerns. Although modern aircraft are considerably quieter than their predecessors, the number of complaints has not decreased as much as expected. Therefore, the aeronautical sector has tried more sociological and/or psychological strategies to gain acceptance through awareness and community engagement. In this regard, noise communication to the public is crucial for managers and policy makers. Noise information is a difficult technical topic for non-experts, which is an issue that must first be addressed to take advantage of the new possibilities that have recently been opened by the internet and information and communication technologies. In this review paper, we have compiled the literature that shows the increasing importance of communicating noise information from aircraft and the variety of indicators used to communicate with the public. We also examined the methods of representing noise data, using visualization strategies, and new tools airports are currently using to address this communication problem. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Reducing flyover noise of propeller-driven aeroplanes by superposition of propeller- and exhaust-noise

    NASA Astrophysics Data System (ADS)

    Kallergis, M.

    Propeller farfield-noise attenuation is presently accomplished by means of a superimposition of piston-engine exhaust noise on the propeller-generated noise in order to produce destructive interference. This objective may be efficiently accomplished by adjusting the relative circumferential position of the propeller blades to the crankshaft. This concept has been theoretically and experimentally verified for an apparatus in which a flange was inserted between the propeller and the driveshaft; this flange can be rotated in steps to shift the sound-wave phase of the propeller relative to the engine exhaust.

  12. Subradiant spontaneous undulator emission through collective suppression of shot noise

    DOE PAGES

    Ratner, D.; Hemsing, E.; Gover, A.; ...

    2015-05-01

    The phenomenon of Dicke’s subradiance, in which the collective properties of a system suppress radiation, has received broad interest in atomic physics. Recent theoretical papers in the field of relativistic electron beams have proposed schemes to achieve subradiance through suppression of shot noise current fluctuations. The resulting “quiet” beam generates less spontaneous radiation than emitted even by a shot noise beam when oscillating in an undulator. Quiet beams could have diverse accelerator applications, including lowering power requirements for seeded free-electron lasers and improving efficiency of hadron cooling. In this paper we present experimental observation of a strong reduction in undulatormore » radiation, demonstrating the feasibility of noise suppression as a practical tool in accelerator physics.« less

  13. Curcumin Reduces the Noise-Exposed Cochlear Fibroblasts Apoptosis

    PubMed Central

    Haryuna, Tengku Siti Hajar; Riawan, Wibi; Nasution, Ardyansyah; Ma'at, Suprapto; Harahap, Juliandi; Adriztina, Indri

    2016-01-01

    Introduction The structural changes underlying permanent noise-induced hearing loss (NIHL) include loss of the sensory hair cells, damage to their stereocilia, and supporting tissues within the cochlear lateral wall. Objective The objective of this study is to demonstrate curcumin as a safe and effective therapeutic agent in the prevention and treatment for fibroblasts damage within the cochlear supporting tissues and lateral wall through cell death pathway. Methods We divided 24 Rattus norvegicus into 4 groups, Group 1: control; Group 2: noise (+); Group 3: noise (+), 50 mg/day curcumin (+); Group 4: noise (+), 100 mg/day curcumin (+). We provided the noise exposure dose at 100 dB SPL for two hours over two weeks and administered the curcumin orally over two weeks. We examined all samples for the expressions of calcineurin, nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), and apoptotic index of cochlear fibroblasts. Results We found significant differences for the expressions of calcineurin (p < 0.05) in all groups, significant differences for the expressions of NFATc1 (p < 0.05) in all groups, except in Groups 1 and 4, and significant differences for the apoptotic index (p < 0.05) in all groups. Conclusion Curcumin proved to be potentially effective in the prevention and treatment for fibroblasts damage within the cochlear supporting tissues and lateral wall regarding the decreased expression of calcineurin, NFATc1, and apoptotic index of cochlear fibroblasts. PMID:27746842

  14. Power Network impedance effects on noise emission of DC-DC converters

    NASA Astrophysics Data System (ADS)

    Esteban, M. C.; Arteche, F.; Iglesias, M.; Gimeno, A.; Arcega, F. J.; Johnson, M.; Cooper, W. E.

    2012-01-01

    The characterization of electromagnetic noise emissions of DC-DC converters is a critical issue that has been analyzed during the desing phase of CMS tracker upgrade. Previous simulation studies showed important variations in the level of conducted emissions when DC-DC converters are loaded/driven by different impedances and power network topologies. Several tests have been performed on real DC-DC converters to validate the Pspice model and simulation results. This paper presents these test results. Conducted noise emissions at the input and at the output terminals of DC-DC converters has been measured for different types of power and FEE impedances. Special attention has been paid to influence on the common-mode emissions by the carbon fiber material used to build the mechanical structure of the central detector. These study results show important recommendations and criteria to be applied in order to decrease the system noise level when integrating the DC-DC.

  15. Further studies of methods for reducing community noise around airports. [aircraft noise - aircraft engines

    NASA Technical Reports Server (NTRS)

    Petersen, R. H.; Barry, D. J.; Kline, D. M.

    1975-01-01

    A simplified method of analysis was used in which all flights at a 'simulated' airport were assumed to operate from one runway in a single direction. For this simulated airport, contours of noise exposure forecast were obtained and evaluated. A flight schedule of the simulated airport which is representative of the 23 major U. S. airports was used. The effect of banning night-time operations by four-engine, narrow-body aircraft in combination with other noise reduction options was studied. The reductions in noise which would occur of two- and three-engine, narrow-body aircraft equipped with a refanned engine was examined. A detailed comparison of the effects of engine cutback on takeoff versus the effects of retrofitting quiet nacelles for narrow-body aircraft was also examined. A method of presenting the effects of various noise reduction options was treated.

  16. Soy Biodiesel Emissions Have Reduced Inflammatory Effects ...

    EPA Pesticide Factsheets

    Toxicity of exhaust from combustion of petroleum diesel (BO), soy-based biodiesel (B100), or a 20% biodiesel/80% petrodiesel mix (B20) was compared in healthy and house dust mite (HDM)-allergic mice. Fuel emissions were diluted to target fine particulate matter (PM2.5) conrentrations of 50, 150, or 500 µg/m(3). Studies in healthy mice showed greater levels of neutrophils and MIP-2 in bronchoaeolar lavage (BAL) fluid 2 h after a single 4-h exposure to BO compared with mice exposed to B20 or B100. No consistent differences in BAL cells and biochemistry, or hematological parameters, were observed after 5 d or 4 weeks of exposure to any of the emissions. Air-exposed HDM-allergc mice had significantly increased responsiveness to methacholine aerosol challenge compared with non-allergic mice. Exposure to any of the emissions for 4 weeks did not further increase responsiveness in either non-allergic or HDM­ allergic mice, and few parameters of allergic inflammation in BAL fluid were altered. Lung and nasal pathology were not significantly different among BO-, B20-, or B100-exposed groups. In HDM-allergic mice, exposure to BO, but not B20 or B100, significantly increased resting peribronchiolar lymph node cell proliferation and production of TH2 cytokines (IL-4, IL-5, and IL-13) and IL-17 in comparison with air-exposed allergic mice. These results suggest that diesel exhaust at a relatively high concentration (500 µg/m(3)) can induce inflammation acutely in healthy m

  17. Creating a Culture of Safety by Reducing Noise Levels in the OR.

    PubMed

    Hogan, Lisa J; Harvey, Renee L

    2015-10-01

    We implemented a quality improvement project to reduce noise levels in the OR in response to complaints from the anesthesia staff members at two community hospitals. Excessive noise has been shown to increase staff member stress, fatigue, distraction, and ineffective communication, which can lead to medical errors. We measured noise levels during anesthesia induction and emergence for 118 different surgical procedures and compared noise levels before and after the improvement project intervention. Staff member education and noise reduction strategies, which included signage, prominent noise meters, and specific suggestions to staff members, helped to significantly reduce the noise level during the anesthetic induction and emergence phases of OR procedures. Copyright © 2015 AORN, Inc. Published by Elsevier Inc. All rights reserved.

  18. An evaluation of some alternative approaches for reducing fan tone noise

    NASA Astrophysics Data System (ADS)

    Dittmar, James H.; Woodward, Richard P.

    1992-02-01

    The potential of two alternative approaches for reducing fan ton noise was investigated in this study. One of these approaches increases the number of rotor blades to shift the tone noise to higher frequencies that are not rated as strongly by the perceived noise scale. This alternative fan also would have a small number of long chord stator vanes which would reduce the stator response and lower rotor-stator interaction noise. Comparison of the conventional and alternative fan concepts showed that this alternative approach has as large or larger a perceived tone noise reduction potential as the conventional approach. The other alternative, a high Mach number inlet, is evaluated both for its noise attenuation and for its change in noise directivity.

  19. An evaluation of some alternative approaches for reducing fan tone noise

    NASA Technical Reports Server (NTRS)

    Dittmar, James H.; Woodward, Richard P.

    1992-01-01

    The potential of two alternative approaches for reducing fan ton noise was investigated in this study. One of these approaches increases the number of rotor blades to shift the tone noise to higher frequencies that are not rated as strongly by the perceived noise scale. This alternative fan also would have a small number of long chord stator vanes which would reduce the stator response and lower rotor-stator interaction noise. Comparison of the conventional and alternative fan concepts showed that this alternative approach has as large or larger a perceived tone noise reduction potential as the conventional approach. The other alternative, a high Mach number inlet, is evaluated both for its noise attenuation and for its change in noise directivity.

  20. Development of a model to assess acoustic treatments to reduce railway noise

    NASA Astrophysics Data System (ADS)

    Jeong, H.; Squicciarini, G.; Thompson, D. J.; Ryue, J.

    2016-09-01

    Porous materials have recently been used in absorptive treatments around railway tracks to reduce noise emissions. To investigate the effect of porous materials, a finite element model has been developed. 2D models for porous materials have been considered either as an equivalent fluid or as a poroelastic material based on the Biot theory. The two models have been validated and compared with each other to check the effect of the skeleton vibration. The poroelastic FE model has been coupled with a 2D acoustic boundary element model for use in railway applications. The results show that it may be necessary to include the frame vibration, especially at low frequencies where a frame resonance occurs. A method for the characterization of porous materials is also discussed. From this it is shown that the elastic properties of the material determine the resonance frequency and the magnitude.

  1. Underwater noise emissions from a drillship in the Arctic.

    PubMed

    Kyhn, Line A; Sveegaard, Signe; Tougaard, Jakob

    2014-09-15

    Wideband sound recordings were made of underwater noise emitted by an active drillship, Stena Forth, working in 484 m of water in Baffin Bay, western Greenland. The recordings were obtained at thirty and one-hundred meters depth. Noise was recorded during both drilling and maintenance work at ranges from 500 m to 38 km. The emitted noise levels were highest during maintenance work with estimated source levels up to 190 dB re 1 μPa (rms), while the source level during drilling was 184 dB re 1 μPa (rms). There were spectral peaks discernible from the background noise to ranges of at least 38 km from the drillship with the main energy below 3 kHz. M-weighted sound pressure levels were virtually identical to broadband levels for low-frequency cetaceans and about 5 dB lower for high-frequency cetaceans. Signals from the dynamic positioning system were clearly detectable at ranges up to two km from the drillship.

  2. 40 CFR 205.152 - Noise emission standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... distance of 6000 km (3730 mi) after the time of sale to the ultimate purchaser, whichever occurs first. (4... section, for an Acoustical Assurance Period of one year or a distance of 3000 km (1865 mi) after the time...), and (5), of this section. (Secs. 10 and 15 of the Noise Control Act, (42 U.S.C. 4909, 4914))...

  3. 40 CFR 205.152 - Noise emission standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... distance of 6000 km (3730 mi) after the time of sale to the ultimate purchaser, whichever occurs first. (4... section, for an Acoustical Assurance Period of one year or a distance of 3000 km (1865 mi) after the time...), and (5), of this section. (Secs. 10 and 15 of the Noise Control Act, (42 U.S.C. 4909, 4914))...

  4. 40 CFR 205.152 - Noise emission standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... distance of 6000 km (3730 mi) after the time of sale to the ultimate purchaser, whichever occurs first. (4... section, for an Acoustical Assurance Period of one year or a distance of 3000 km (1865 mi) after the time...), and (5), of this section. (Secs. 10 and 15 of the Noise Control Act, (42 U.S.C. 4909, 4914))...

  5. 40 CFR 205.152 - Noise emission standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... distance of 6000 km (3730 mi) after the time of sale to the ultimate purchaser, whichever occurs first. (4... section, for an Acoustical Assurance Period of one year or a distance of 3000 km (1865 mi) after the time...), and (5), of this section. (Secs. 10 and 15 of the Noise Control Act, (42 U.S.C. 4909, 4914))...

  6. Reducing Noise by Repetition: Introduction to Signal Averaging

    ERIC Educational Resources Information Center

    Hassan, Umer; Anwar, Muhammad Sabieh

    2010-01-01

    This paper describes theory and experiments, taken from biophysics and physiological measurements, to illustrate the technique of signal averaging. In the process, students are introduced to the basic concepts of signal processing, such as digital filtering, Fourier transformation, baseline correction, pink and Gaussian noise, and the cross- and…

  7. Reducing Noise by Repetition: Introduction to Signal Averaging

    ERIC Educational Resources Information Center

    Hassan, Umer; Anwar, Muhammad Sabieh

    2010-01-01

    This paper describes theory and experiments, taken from biophysics and physiological measurements, to illustrate the technique of signal averaging. In the process, students are introduced to the basic concepts of signal processing, such as digital filtering, Fourier transformation, baseline correction, pink and Gaussian noise, and the cross- and…

  8. Integrated Spacesuit Audio System Enhances Speech Quality and Reduces Noise

    NASA Technical Reports Server (NTRS)

    Huang, Yiteng Arden; Chen, Jingdong; Chen, Shaoyan Sharyl

    2009-01-01

    A new approach has been proposed for increasing astronaut comfort and speech capture. Currently, the special design of a spacesuit forms an extreme acoustic environment making it difficult to capture clear speech without compromising comfort. The proposed Integrated Spacesuit Audio (ISA) system is to incorporate the microphones into the helmet and use software to extract voice signals from background noise.

  9. Effects of Intermittent Emission: Noise Inventory for the Scintillating Pulsar B0834+06

    NASA Astrophysics Data System (ADS)

    Gwinn, C. R.; Johnson, M. D.; Smirnova, T. V.; Stinebring, D. R.

    2011-05-01

    We compare signal and noise for observations of the scintillating pulsar B0834+06, using very long baseline interferometry and a single-dish spectrometer. Comparisons between instruments and with models suggest that amplitude variations of the pulsar strongly affect the amount and distribution of self-noise. We show that noise follows a quadratic polynomial with flux density, in spectral observations. Constant coefficients, indicative of background noise, agree well with expectation; whereas second-order coefficients, indicative of self-noise, are ≈3 times values expected for a pulsar with constant on-pulse flux density. We show that variations in flux density during the 10 s integration accounts for the discrepancy. In the secondary spectrum, ≈97% of spectral power lies within the pulsar's typical scintillation bandwidth and timescale; an extended scintillation arc contains ≈3%. For a pulsar with constant on-pulse flux density, noise in the dynamic spectrum will appear as a uniformly distributed background in the secondary spectrum. We find that this uniform noise background contains 95% of noise in the dynamic spectrum for interferometric observations; but only 35% of noise in the dynamic spectrum for single-dish observations. Receiver and sky dominate noise for our interferometric observations, whereas self-noise dominates for single-dish. We suggest that intermittent emission by the pulsar, on timescales <300 μs, concentrates self-noise near the origin in the secondary spectrum, by correlating noise over the dynamic spectrum. We suggest that intermittency sets fundamental limits on pulsar astrometry or timing. Accounting of noise may provide means for detection of intermittent sources, when effects of propagation are unknown or impractical to invert.

  10. HHC study in the DNW to reduce BVI noise - An analysis

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Booth, Earl R., Jr.; Boyd, D. D., Jr.; Splettstoesser, Wolf R.; Schultz, Klaus -J.; Kube, Roland; Niesl, Georg H.; Streby, Olivier

    1991-01-01

    The noise of an aeroelastically scaled helicopter rotor has been studied in the German-Dutch wind tunnel in order to assess the utility of higher-harmonic control (HHC) in reducing blade-vortex interaction (BVI) noise. Acoustic data are presented for 3/rev, 4/rev, and 5/rev HHC, as applied to a typical landing approach rotor operating condition; noise reduction of up to 6 dB were found for advancing-blade BVI noise radiating upstream of the rotor, as well as for retreating blade BVI noise radiating below and downstream of the rotor.

  11. Reducing greenhouse gas emissions in Czechoslovakia

    SciTech Connect

    Kostalova, M. ); Suk, J. ); Kolar, S. )

    1991-12-01

    In this paper are presented important findings on the potential for energy conservation and carbon emissions reduction over the coming decades in Czechoslovakia. The authors describe the state of the energy use in Czechoslovakia today and the measures required to transform its energy system to a market-based economy oriented towards the environmental goal of decreased energy intensity. This work furthers our understanding of the need for energy efficiency in the newly forming market economies of East and Central Europe. This paper is part of a series of country studies sponsored by the Global Climate Division of the Office of Policy, Planning, and Evaluation, United States Environmental Protection Agency (EPA). We have completed similar studies in Canada, the former Soviet Union, France, Hungary, Italy, Japan, Poland the United Kingdom, and the United States. Research is currently underway or planned in Bulgaria, Romania, and Ukraine.

  12. NASA Collaborative Research on the Ultra High Bypass Engine Cycle and Potential Benefits for Noise, Performance, and Emissions

    NASA Technical Reports Server (NTRS)

    Hughes, Christopher E.

    2013-01-01

    The National Aeronautics and Space Administration has taken an active role in collaborative research with the U.S. aerospace industry to investigate technologies to minimize the impact of aviation on the environment. In December 2006, a new program, called the Fundamental Aeronautics Program, was established to enhance U.S. aeronautics technology and conduct research on energy, efficiency and the environment. A project within the overall program, the Subsonic Fixed Wing Project, was formed to focus on research related to subsonic aircraft with specific goals and time based milestones to reduce aircraft noise, emissions and fuel burn. This paper will present an overview of the Subsonic Fixed Wing Project environmental goals and describe a segment of the current research within NASA and also were worked collaboratively with partners from the U.S. aerospace industry related to the next generation of aircraft that will have lower noise, emissions and fuel burn.

  13. A research to reduce interior noise in general aviation airplanes. General aviation interior noise study

    NASA Technical Reports Server (NTRS)

    Roskam, J.; Muirhead, V. U.; Smith, H. W.; Peschier, T. D.

    1977-01-01

    The construction, calibration, and properties of a facility for measuring sound transmission through aircraft type panels are described along with the theoretical and empirical methods used. Topics discussed include typical noise source, sound transmission path, and acoustic cabin properties and their effect on interior noise. Experimental results show an average sound transmission loss in the mass controlled frequency region comparable to theoretical predictions. The results also verify that transmission losses in the stiffness controlled region directly depend on the fundamental frequency of the panel. Experimental and theoretical results indicate that increases in this frequency, and consequently in transmission loss, can be achieved by applying pressure differentials across the specimen.

  14. Improvements in spiral-bevel gears to reduce noise and increase strength

    NASA Astrophysics Data System (ADS)

    Lewicki, David G.; Handschuh, Robert F.; Henry, Zachary S.; Litvin, Faydor L.

    1994-05-01

    Advanced-design spiral-bevel gears were tested in an OH-58D helicopter transmission using the NASA 500 hp Helicopter Transmission Test Stand. Four different gear designs were tested. The four designs tested were the current design of the OH-58D transmission, a higher-strength design the same as the current but with an increased fillet radius to reduce gear tooth bending stress, and two versions of a lower-noise design the same as the high-strength but with modified tooth geometry to reduce transmission error and noise. Noise, vibration, and tooth strain tests were performed and significant gear stress and noise reductions were achieved.

  15. Improvements in Spiral-Bevel Gears to Reduce Noise and Increase Strength

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Handschuh, Robert F.; Henry, Zachary S.; Litvin, Faydor L.

    1994-01-01

    Advanced-design spiral-bevel gears were tested in an OH-58D helicopter transmission using the NASA 500 hp Helicopter Transmission Test Stand. Four different gear designs were tested. The four designs tested were the current design of the OH-58D transmission, a higher-strength design the same as the current but with an increased fillet radius to reduce gear tooth bending stress, and two versions of a lower-noise design the same as the high-strength but with modified tooth geometry to reduce transmission error and noise. Noise, vibration, and tooth strain tests were performed and significant gear stress and noise reductions were achieved.

  16. Subsonic Jet Noise Reduced With Improved Internal Exhaust Gas Mixers

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Aircraft noise pollution is becoming a major environmental concern for the world community. The Federal Aviation Administration (FAA) is responding to this concern by imposing more stringent noise restrictions for aircraft certification then ever before to keep the U.S. industry competitive with the rest of the world. At the NASA Lewis Research Center, attempts are underway to develop noise-reduction technology for newer engines and for retrofitting existing engines so that they are as quiet as (or quieter than) required. Lewis conducted acoustic and Laser Doppler Velocimetry (LDV) tests using Pratt & Whitney's Internal Exhaust Gas Mixers (IEGM). The IEGM's mix the core flow with the fan flow prior to their common exhaust. All tests were conducted in Lewis' Aero-Acoustic Propulsion Laboratory--a semihemispheric dome open to the ambient atmosphere. This was the first time Laser Doppler Velocimetry was used in such a facility at Lewis. Jet exhaust velocity and turbulence and the internal velocity fields were detailed. Far-field acoustics were also measured. Pratt & Whitney provided 1/7th scale model test hardware (a 12-lobe mixer, a 20-lobe mixer, and a splitter) for 1.7 bypass ratio engines, and NASA provided the research engineers, test facility, and test time. The Pratt & Whitney JT8D-200 engine power conditions were used for all tests.

  17. Effects of N-Acetylcysteine on Thresholds and Otoacoustic Emissions Following Noise Exposure

    DTIC Science & Technology

    2004-12-01

    wearing ear plugs, muffs, etc.. The current study evaluated the effectiveness of one antioxidant, N- acetylcysteine ( NAC ), on temporary cochlear changes...EFFECTS OF N- ACETYLCYSTEINE ON THRESHOLDS AND OTOACOUSTIC EMISSIONS FOLLOWING NOISE EXPOSURE Barbara Acker-Mills, Ph.D*., CPT Martin Robinette...in humans by using both behavioral and physiological measures. Two levels of supplement (900 mg of NAC or placebo) and two levels of noise (60 dB

  18. A Noise and Emissions Assessment of the N3-X Transport

    NASA Technical Reports Server (NTRS)

    Berton, Jeffrey J.; Haller, William J.

    2014-01-01

    Analytical predictions of certification noise and exhaust emissions for NASA's N3-X - a notional, hybrid wingbody airplane - are presented in this paper. The N3-X is a 300-passenger concept transport propelled by an array of fans distributed spanwise near the trailing edge of the wingbody. These fans are driven by electric motors deriving power from twin generators driven by turboshaft engines. Turboelectric distributed hybrid propulsion has the potential to dramatically increase the propulsive efficiency of aircraft. The noise and exhaust emission estimates presented here are generated using NASA's conceptual design systems analysis tools with several key modifications to accommodate this unconventional architecture. These tools predict certification noise and the emissions of oxides of nitrogen by leveraging data generated from a recent analysis of the N3-X propulsion system.

  19. Use of First Order Reversal Curve Measurements to Understand Barkhausen Noise Emission in Nuclear Steel

    SciTech Connect

    McCloy, John S.; Ramuhalli, Pradeep; Henager, Charles H.

    2013-02-25

    A prototypical ferritic/martensitic alloy, HT-9, of interest to the nuclear materials community was investigated for microstructure effects on Barkhausen noise emission and first-order reversal curve (FORC) analysis for three different heat-treated samples. It was observed that Barkhausen noise emission and reversible component of magnetization, computed from the FORC data, decreased with increasing measured mechanical hardness. The results are discussed in terms of the use of magnetic signatures for use in nondestructive interrogation of radiation damage and other microstructural changes in ferritic/martensitic alloys. FORC analysis is shown to be particularly useful for detailed characterization of defect density and pinning, which can be correlated to bulk non-destructive evaluation field measurements such as Barkhausen noise emission.

  20. Apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, Rhett L.; Ambrose, W. Patrick; Demas, James N.; Goodwin, Peter M.; Johnson, Mitchell E.; Keller, Richard A.; Petty, Jeffrey T.; Schecker, Jay A.; Wu, Ming

    1998-01-01

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

  1. Apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, R.L.; Ambrose, W.P.; Demas, J.N.; Goodwin, P.M.; Johnson, M.E.; Keller, R.A.; Petty, J.T.; Schecker, J.A.; Wu, M.

    1998-11-10

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region. 6 figs.

  2. A Method to Further Reduce the Perceived Noise of Low Tip Speed Fans

    NASA Technical Reports Server (NTRS)

    Dittmar, James H.

    2000-01-01

    The use of low tip speed, high bypass ratio fans is a method for reducing the noise of turbofan jet engines. These fans typically have a low number of rotor blades and a number of stator vanes sufficient to achieve cut-off of the blade passing tone. Their perceived noise levels are typically dominated by broadband noise caused by the rotor wake turbulence - stator interaction mechanism. A 106 bladed, 1100 ft/sec takeoff tip speed fan, the Alternative Low Noise Fan, has been tested and shown to have reduced broadband noise. This reduced noise is believed to be the result of the high rotor blade number. Although this fan with 106 blades would not be practical with materials as they exist today, a fan with 50 or so blades could be practically realized. A noise estimate has indicated that such a 50 bladed, low tip speed fan could be 2 to 3 EPNdB quieter than an 18 bladed fan. If achieved, this level of noise reduction would be significant and points to the use of a high blade number, low tip speed fan as a possible configuration for reduced fan noise.

  3. Reducing coherent noise in interference systems using the phase modulation technique.

    PubMed

    Cui, Ji-Wen; Tao, Zhang; Liu, Zhao-Bo; Tan, Jiu-Bin

    2015-08-20

    The phase modulation technique is adopted to reduce the coherent noise that arises from spurious interference. By choosing an appropriate driving signal, the method can reduce the coherent function of coherent noise to a great degree while keeping the coherent function of a coherent signal nearly unchanged. Simulation results show that for the grating interferometer, the phase error caused by coherent noise is reduced by 81.53% on average. For the Twyman interferometer, the fringe quality and contrast deteriorated by coherent noise are significantly improved. Furthermore, an experiment is set up in the phase-modulated Twyman interferometer to verify the feasibility of the principle. It is concluded that the method is effective to reduce the coherent noise in interference systems.

  4. Evaluation of methods of reducing community noise impact around San Jose municipal airport

    NASA Technical Reports Server (NTRS)

    Glick, J. M.; Shevell, R. S.; Bowles, J. V.

    1975-01-01

    A computer simulation of the airport noise impact on the surrounding communities was used to evaluate alternate operational procedures, improved technology, and land use conversion as methods of reducing community noise impact in the airport vicinity. In addition, a constant density population distribution was analyzed for possible application to other airport communities with fairly uniform population densities and similar aircraft operational patterns. The introduction of sound absorption material (SAM) was found to reduce community noise annoyance by over 25 percent, and the introduction of refan was found to reduce community annoyance by over 60 percent. Replacing the present aircraft was found to reduce the noise problem to very small proportions, and the introduction of an advanced technology twin was found to essentially eliminate the community noise problem.

  5. Determination and Applications of Environmental Costs at Different Sized Airports: Aircraft Noise and Engine Emissions

    NASA Technical Reports Server (NTRS)

    Lu, Cherie; Lierens, Abigail

    2003-01-01

    With the increasing trend of charging for externalities and the aim of encouraging the sustainable development of the air transport industry, there is a need to evaluate the social costs of these undesirable side effects, mainly aircraft noise and engine emissions, for different airports. The aircraft noise and engine emissions social costs are calculated in monetary terms for five different airports, ranging from hub airports to small regional airports. The number of residences within different levels of airport noise contours and the aircraft noise classifications are the main determinants for accessing aircraft noise social costs. Whist, based on the damages of different engine pollutants on the human health, vegetation, materials, aquatic ecosystem and climate, the aircraft engine emissions social costs vary from engine types to aircraft categories. The results indicate that the relationship appears to be curvilinear between environmental costs and the traffic volume of an airport. The results and methodology of environmental cost calculation could input for to the proposed European wide harmonized noise charges as well as the social cost benefit analysis of airports.

  6. Numerical Simulation of Flow-Induced Noise in High Pressure Reducing Valve

    PubMed Central

    Wei, Lin; Zhu, Guorong; Qian, Jinyuan; Fei, Yang; Jin, Zhijiang

    2015-01-01

    The main objective of this paper is to study the characteristics of flow-induced noise in high pressure reducing valve (HPRV) and to provide some guidance for noise control. Based on computational fluid dynamics (CFD), numerical method was used to compute flow field. Ffowcs Williams and Hawkings Model was applied to obtain acoustic signals. The unsteady flow field shows that noise sources are located at the bottom of plug for valve without perforated plate, and noise sources are behind the plate for valve with perforated plate. Noise directivity analysis and spectrum characteristics indicate that the perforated plate could help to reduce noise effectively. Inlet pressure has great effects on sound pressure level (SPL). The higher inlet pressure will lead to larger SPL at high frequency. When the maximum Ma is close to 1, SPL at low frequency becomes very high. PMID:26061396

  7. OPTIONS FOR REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

    EPA Science Inventory

    The report was prepared to assist personnel responsible for the design, construction, and maintenance of retail food refrigeration equipment in making knowledgeable decisions regarding the implementation of refrigerant-emissions-reducing practices and technologies. It characteriz...

  8. OPTIONS FOR REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS

    EPA Science Inventory

    The report was prepared to assist personnel responsible for the design, construction, and maintenance of retail food refrigeration equipment in making knowledgeable decisions regarding the implementation of refrigerant-emissions-reducing practices and technologies. It characteriz...

  9. Reducing Supply Chain GHG Emissions from LCD Panel Manufacturing Webinar

    EPA Pesticide Factsheets

    Fluorinated greenhouse gases (F-GHGs) are among the most potent and persistent greenhouse gases contributing to global climate change. Learn about the manufacturing processes which release F-GHGs, and how LCD suppliers are working to reduce emissions.

  10. The use of wavelet filters for reducing noise in posterior fossa Computed Tomography images

    SciTech Connect

    Pita-Machado, Reinado; Perez-Diaz, Marlen Lorenzo-Ginori, Juan V. Bravo-Pino, Rolando

    2014-11-07

    Wavelet transform based de-noising like wavelet shrinkage, gives the good results in CT. This procedure affects very little the spatial resolution. Some applications are reconstruction methods, while others are a posteriori de-noising methods. De-noising after reconstruction is very difficult because the noise is non-stationary and has unknown distribution. Therefore, methods which work on the sinogram-space don’t have this problem, because they always work over a known noise distribution at this point. On the other hand, the posterior fossa in a head CT is a very complex region for physicians, because it is commonly affected by artifacts and noise which are not eliminated during the reconstruction procedure. This can leads to some false positive evaluations. The purpose of our present work is to compare different wavelet shrinkage de-noising filters to reduce noise, particularly in images of the posterior fossa within CT scans in the sinogram-space. This work describes an experimental search for the best wavelets, to reduce Poisson noise in Computed Tomography (CT) scans. Results showed that de-noising with wavelet filters improved the quality of posterior fossa region in terms of an increased CNR, without noticeable structural distortions.

  11. Texturing Copper To Reduce Secondary Emission Of Electrons

    NASA Technical Reports Server (NTRS)

    Jensen, Kenneth A.; Curren, Arthur N.; Roman, Robert F.

    1995-01-01

    Ion-beam process produces clean, deeply textured surfaces on copper substrates with reduced secondary electron emission. In process, molybdenum ring target positioned above and around copper substrate. Target potential repeatedly switched on and off. Switching module described in "High-Voltage MOSFET Switching Circuit" (LEW-15986). Useful for making collector electrodes for traveling-wave-tube and klystron microwave amplifiers, in which secondary emission of electrons undesirable because of reducing efficiency.

  12. Texturing Copper To Reduce Secondary Emission Of Electrons

    NASA Technical Reports Server (NTRS)

    Jensen, Kenneth A.; Curren, Arthur N.; Roman, Robert F.

    1995-01-01

    Ion-beam process produces clean, deeply textured surfaces on copper substrates with reduced secondary electron emission. In process, molybdenum ring target positioned above and around copper substrate. Target potential repeatedly switched on and off. Switching module described in "High-Voltage MOSFET Switching Circuit" (LEW-15986). Useful for making collector electrodes for traveling-wave-tube and klystron microwave amplifiers, in which secondary emission of electrons undesirable because of reducing efficiency.

  13. Estimating atmospheric parameters and reducing noise for multispectral imaging

    DOEpatents

    Conger, James Lynn

    2014-02-25

    A method and system for estimating atmospheric radiance and transmittance. An atmospheric estimation system is divided into a first phase and a second phase. The first phase inputs an observed multispectral image and an initial estimate of the atmospheric radiance and transmittance for each spectral band and calculates the atmospheric radiance and transmittance for each spectral band, which can be used to generate a "corrected" multispectral image that is an estimate of the surface multispectral image. The second phase inputs the observed multispectral image and the surface multispectral image that was generated by the first phase and removes noise from the surface multispectral image by smoothing out change in average deviations of temperatures.

  14. Method of calibrating an interferometer and reducing its systematic noise

    NASA Technical Reports Server (NTRS)

    Hammer, Philip D. (Inventor)

    1997-01-01

    Methods of operation and data analysis for an interferometer so as to eliminate the errors contributed by non-responsive or unstable pixels, interpixel gain variations that drift over time, and spurious noise that would otherwise degrade the operation of the interferometer are disclosed. The methods provide for either online or post-processing calibration. The methods apply prescribed reversible transformations that exploit the physical properties of interferograms obtained from said interferometer to derive a calibration reference signal for subsequent treatment of said interferograms for interpixel gain variations. A self-consistent approach for treating bad pixels is incorporated into the methods.

  15. Heat pipes to reduce engine exhaust emissions

    NASA Technical Reports Server (NTRS)

    Schultz, D. F. (Inventor)

    1984-01-01

    A fuel combustor is presented that consists of an elongated casing with an air inlet conduit portion at one end, and having an opposite exit end. An elongated heat pipe is mounted longitudinally in the casing and is offset from and extends alongside the combustion space. The heat pipe is in heat transmitting relationship with the air intake conduit for heating incoming air. A guide conduit structure is provided for conveying the heated air from the intake conduit into the combustion space. A fuel discharge nozzle is provided to inject fuel into the combustion space. A fuel conduit from a fuel supply source has a portion engaged in heat transfer relationship of the heat pipe for preheating the fuel. The downstream end of the heat pipe is in heat transfer relationship with the casing and is located adjacent to the downstream end of the combustion space. The offset position of the heat pipe relative to the combustion space minimizes the quenching effect of the heat pipe on the gaseous products of combustion, as well as reducing coking of the fuel on the heat pipe, thereby improving the efficiency of the combustor.

  16. Some design philosophy for reducing the community noise of advanced counter-rotation propellers

    NASA Technical Reports Server (NTRS)

    Dittmar, J. H.

    1985-01-01

    Advanced counter-rotation propellers have been indicated as possibly generating an unacceptable amount of noise for the people living near an airport. This report has explored ways to reduce this noise level, which is treated as being caused by the interaction of the upstream propeller wakes and vortices with the downstream propeller. The noise reduction techniques fall into two categories: (1) reducing the strength of the wakes and vortices, and (2) reducing the response of the downstream blades to them. The noise from the wake interaction was indicated as being reduced by increased propeller spacing and decreased blade drag coefficient. The vortex-interaction noise could be eliminated by having the vortex pass over the tips of the downstream blade, and it could be reduced by increased spacing or decreased initial circulation. The downstream blade response could be lessened by increasing the reduced frequency parameter omega or by phasing of the response from different sections to have a mutual cancellation effect. Uneven blade to blade spacing for the downstream blading was indicated as having a possible effect on the annoyance of counter-rotation propeller noise. Although there are undoubtedly additional methods of noise reduction not covered in this report, the inclusion of the design methods discussed would potentially result in a counter-rotation propeller that is acceptably quiet.

  17. Microwave oscillator with reduced phase noise by negative feedback incorporating microwave signals with suppressed carrier

    NASA Technical Reports Server (NTRS)

    Dick, G. J.; Saunders, J.

    1989-01-01

    Oscillator configurations which reduce the effect of 1/f noise sources for both direct feedback and stabilized local oscillator (STALO) circuits are developed and analyzed. By appropriate use of carrier suppression, a small signal is generated which suffers no loss of loop phase information or signal-to-noise ratio. This small signal can be amplified without degradation by multiplicative amplifier noise, and can be detected without saturation of the detector. Together with recent advances in microwave resonator Qs, these circuit improvements will make possible lower phase noise than can be presently achieved without the use of cryogenic devices.

  18. Brownian ratchets: How stronger thermal noise can reduce diffusion

    NASA Astrophysics Data System (ADS)

    Spiechowicz, Jakub; Kostur, Marcin; Łuczka, Jerzy

    2017-02-01

    We study diffusion properties of an inertial Brownian motor moving on a ratchet substrate, i.e., a periodic structure with broken reflection symmetry. The motor is driven by an unbiased time-periodic symmetric force that takes the system out of thermal equilibrium. For selected parameter sets, the system is in a non-chaotic regime in which we can identify a non-monotonic dependence of the diffusion coefficient on temperature: for low temperature, it initially increases as the temperature grows, passes through its local maximum, next starts to diminish reaching its local minimum, and finally it monotonically increases in accordance with the Einstein linear relation. Particularly interesting is the temperature interval in which diffusion is suppressed by the thermal noise, and we explain this effect in terms of transition rates of a three-state stochastic model.

  19. Reducing Centroid Error Through Model-Based Noise Reduction

    NASA Technical Reports Server (NTRS)

    Lee, Shinhak

    2006-01-01

    A method of processing the digitized output of a charge-coupled device (CCD) image detector has been devised to enable reduction of the error in computed centroid of the image of a point source of light. The method involves model-based estimation of, and correction for, the contributions of bias and noise to the image data. The method could be used to advantage in any of a variety of applications in which there are requirements for measuring precise locations of, and/or precisely aiming optical instruments toward, point light sources. In the present method, prior to normal operations of the CCD, one measures the point-spread function (PSF) of the telescope or other optical system used to project images on the CCD. The PSF is used to construct a database of spot models representing the nominal CCD pixel outputs for a point light source projected onto the CCD at various positions incremented by small fractions of a pixel.

  20. Persistence of reduced neuromotor noise in long-term motor skill learning.

    PubMed

    Huber, Meghan E; Kuznetsov, Nikita; Sternad, Dagmar

    2016-12-01

    It is well documented that variability in motor performance decreases with practice, yet the neural and computational mechanisms that underlie this decline, particularly during long-term practice, are little understood. Decreasing variability is frequently examined in terms of error corrections from one trial to the next. However, the ubiquitous noise from all levels of the sensorimotor system is also a significant contributor to overt variability. While neuromotor noise is typically assumed and modeled as immune to practice, the present study challenged this notion. We investigated the long-term practice of a novel motor skill to test whether neuromotor noise can be attenuated, specifically when aided by reward. Results showed that both reward and self-guided practice over 11 days improved behavior by decreasing noise rather than effective error corrections. When the challenge for obtaining reward increased, subjects reduced noise even further. Importantly, when task demands were relaxed again, this reduced level of noise persisted for 5 days. A stochastic learning model replicated both the attenuation and persistence of noise by scaling the noise amplitude as a function of reward. More insight into variability and intrinsic noise and its malleability has implications for training and rehabilitation interventions. Copyright © 2016 the American Physiological Society.

  1. Magnetic hysteresis and Barkhausen noise emission analysis of magnetic materials and composites

    NASA Astrophysics Data System (ADS)

    Prabhu Gaunkar, Neelam

    specialchapt{ABSTRACT}. Barkhausen emission studies have been used to analyze the effect of residual stresses in ferromagnetic materials. The stresses generated due to mechanical wear and tear, abrasion and prolonged use can also lead to phase changes within the material. These phase changes can cause damage to the structural parts and should be prevented. In this study we analyze the magnetic hysteresis and Barkhausen noise profile of materials with more than one ferromagnetic phase. The correlation between the hysteresis and Barkhausen noise profiles for such materials is studied. Secondary Barkhausen emission peaks can be simulated for such materials. Experimental observations are compared with simulation measurements. Drawing a correlation between the secondary emergent peaks and the composition of each secondary phase should lead to an improved technique for non-destructive characterization of ferromagnetic materials. . Improved sensor-to-specimen coupling is also essential for conducting Barkhausen noise measurements of multiphase materials which may also have different surface geometries. A finite element study was conducted to optimize the design parameters of the magnetizing core in a Barkhausen noise sensor. Several sensor parameters inclusive of core material, core-tip curvature, core length and pole spacing were studied. A procedure for developing a high sensitivity Barkhausen noise sensor by design optimization based on finite element simulations has been demonstrated. The study also shows the applicability of Barkhausen emission and magnetic hysteresis analysis as advanced tools of non-destructive characterization of ferromagnetic materials.

  2. Study of evoked otoacoustic emissions and suppression effect on workers exposed to pesticides and noise.

    PubMed

    Alcarás, Patricia Arruda de Souza; Larcerda, Adriana Bender Moreira de; Marques, Jair Mendes

    2013-01-01

    To analyze the findings for Evoked Otoacoustic Emissions (EOEA) and suppression effect in workers with normal hearing exposed to pesticides and noise . The sample consisted of 55 participants with normal hearing, with ages ranging from 18 to 35 years, divided into two groups: one group exposed to noise and pesticides (GRA) and a control group (CG). The GRA was composed of 25 participants exposed to a representative average level of daily occupational noise exposure of 86 dBA and organophosphate-type pesticides, whereas the GC was composed of 30 participants who were not exposed to noise or pesticides. All participants underwent Transient Evoked Otoacoustic Emissions (TEOAE) and Distortion Product Otoacoustic Emissions (DPOAE) examinations and research of the suppression effect. The findings revealed differences between the results of TEOAE and DPOAE exams between GRA and GC groups. GRA participants showed worse results in EOAE findings. Regarding the suppression effect, lesser effects were observed in the GRA. The results suggest that the study of EOAE and suppression effect can be used in early identification of hearing damage to workers simultaneously exposed to pesticides and noise.

  3. Nutrient Plasma Levels Achieved During Treatment that Reduces Noise-Induced Hearing Loss

    PubMed Central

    Le Prell, C. G.; Dolan, D. F.; Bennett, D. C.; Boxer, P. A.

    2011-01-01

    Hearing loss encompasses both temporary and permanent deficits. If temporary threshold shift (TTS) and permanent threshold shift (PTS) share common pathological mechanisms, then agents that reduce PTS should also reduce TTS. Several antioxidant agents have reduced PTS in rodent models; however, reductions in TTS have been inconsistent. This study first determined whether dietary antioxidants (beta-carotene, and vitamins C and E) delivered in combination with magnesium (Mg) reliably increase plasma concentrations of the active agents. Then, additional manipulations tested the hypothesis that these nutrients reduce acute TTS insult in the first 24 hours following loud sound, as well as longer lasting changes in hearing measured up to 7 days post-noise. Saline or nutrients were administered to guinea pigs prior to and after noise exposure. Sound-evoked electrophysiological responses were measured before noise, with tests repeated 1-hour post-noise, as well as 1-, 3-, 5-, and 7-days post-noise. All subjects showed significant functional recovery; subjects treated with nutrients recovered more rapidly, and had better hearing outcomes at early post-noise times as well as the final test time. Thus, this combination of nutrients, which produced significant increases in plasma concentrations of vitamins C and E and Mg, effectively reduced hearing loss at multiple post-noise times. These data suggest free radical formation contributes to TTS as well as PTS insults, and suggest a potential opportunity to prevent TTS in human populations. PMID:21708356

  4. 75 FR 57191 - Compliance With Interstate Motor Carrier Noise Emission Standards: Exhaust Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-20

    ... Federal Motor Carrier Safety Administration 49 CFR Part 325 RIN-2126-AB31 Compliance With Interstate Motor Carrier Noise Emission Standards: Exhaust Systems AGENCY: Federal Motor Carrier Safety Administration, DOT... Association (TMA), the Federal Motor Carrier Safety Administration (FMCSA) amends its regulations to eliminate...

  5. Fluids and Combustion Facility Acoustic Emissions Controlled by Aggressive Low-Noise Design Process

    NASA Technical Reports Server (NTRS)

    Cooper, Beth A.; Young, Judith A.

    2004-01-01

    The Fluids and Combustion Facility (FCF) is a dual-rack microgravity research facility that is being developed by Northrop Grumman Information Technology (NGIT) for the International Space Station (ISS) at the NASA Glenn Research Center. As an on-orbit test bed, FCF will host a succession of experiments in fluid and combustion physics. The Fluids Integrated Rack (FIR) and the Combustion Integrated Rack (CIR) must meet ISS acoustic emission requirements (ref. 1), which support speech communication and hearing-loss-prevention goals for ISS crew. To meet these requirements, the NGIT acoustics team implemented an aggressive low-noise design effort that incorporated frequent acoustic emission testing for all internal noise sources, larger-scale systems, and fully integrated racks (ref. 2). Glenn's Acoustical Testing Laboratory (ref. 3) provided acoustical testing services (see the following photograph) as well as specialized acoustical engineering support as part of the low-noise design process (ref. 4).

  6. A new VOX technique for reducing noise in voice communication systems. [voice operated keying

    NASA Technical Reports Server (NTRS)

    Morris, C. F.; Morgan, W. C.; Shack, P. E.

    1974-01-01

    A VOX technique for reducing noise in voice communication systems is described which is based on the separation of voice signals into contiguous frequency-band components with the aid of an adaptive VOX in each band. It is shown that this processing scheme can effectively reduce both wideband and narrowband quasi-periodic noise since the threshold levels readjust themselves to suppress noise that exceeds speech components in each band. Results are reported for tests of the adaptive VOX, and it is noted that improvements can still be made in such areas as the elimination of noise pulses, phoneme reproduction at high-noise levels, and the elimination of distortion introduced by phase delay.

  7. Technology Opportunities to Reduce U.S. Greenhouse Gas Emissions

    SciTech Connect

    National Lab Directors, . .

    2001-04-05

    The rise in greenhouse gas emissions from fossil fuel combustion and industrial and agricultural activities has aroused international concern about the possible impacts of these emissions on climate. Greenhouse gases--mostly carbon dioxide, some methane, nitrous oxide and other trace gases--are emitted to the atmosphere, enhancing an effect in which heat reflected from the earth's surface is kept from escaping into space, as in a greenhouse. Thus, there is concern that the earth's surface temperature may rise enough to cause global climate change. Approximately 90% of U.S. greenhouse gas emissions from anthropogenic sources come from energy production and use, most of which are a byproduct of the combustion of fossil fuels. On a per capita basis, the United States is one of the world's largest sources of greenhouse gas emissions, comprising 4% of the world's population, yet emitting 23% of the world's greenhouse gases. Emissions in the United States are increasing at around 1.2% annually, and the Energy Information Administration forecasts that emissions levels will continue to increase at this rate in the years ahead if we proceed down the business-as-usual path. President Clinton has presented a two-part challenge for the United States: reduce greenhouse gas emissions and grow the economy. Meeting the challenge will mean that in doing tomorrow's work, we must use energy more efficiently and emit less carbon for the energy expended than we do today. To accomplish these goals, President Clinton proposed on June 26, 1997, that the United States ''invest more in the technologies of the future''. In this report to Secretary of Energy Pena, 47 technology pathways are described that have significant potential to reduce carbon dioxide emissions. The present study was completed before the December 1997 United Nations Framework Convention on Climate Change and is intended to provide a basis to evaluate technology feasibility and options to reduce greenhouse gas emissions

  8. Using mindfulness to reduce the health effects of community reaction to aircraft noise.

    PubMed

    Hede, Andrew J

    2017-01-01

    This paper investigates whether mindfulness-based interventions might ameliorate the detrimental health effects of aircraft noise on residential communities. Numerous empirical studies over the past 50 years have demonstrated the increasing negative impact of aircraft noise on residents worldwide. However, extensive database searches have revealed no published studies on psychological interventions that reduce residents' reactivity to environmental noise. By contrast, there has been extensive research over several decades confirming the effectiveness of mindfulness-based stress reduction training in lowering people's stress from work and life. Considering that stress is a major component of aircraft noise reaction, it would seem worth assessing whether mindfulness-based interventions might be effective in reducing the health effects of aircraft noise. It appears that no existing conceptualization of mindfulness specifically accounts for noise as a stressor. Conceptual Analysis: A new conceptual model is presented here which explains how mindfulness can reduce noise reactivity. Two types of mindfulness are distinguished: an active form (meta-mindfulness) and a passive form (supra-mindfulness). It is posited that meta-mindfulness can facilitate "cognitive defusion" which research has confirmed as enabling people to disconnect from their own dysfunctional thoughts. In the case of aircraft noise, negative thinking associated with residents' reactive experiences can exacerbate the health effects they suffer. The present model further proposes that supra-mindfulness can enable an individual to disengage their own sense of identity from the often overwhelming negative thoughts which can define their existence when they are consumed by extreme noise annoyance. The mindfulness processes of defusion and disidentification are postulated to be the key efficacy mechanisms potentially responsible for reducing reactivity to aircraft noise. This approach can be evaluated by

  9. Using Mindfulness to Reduce the Health Effects of Community Reaction to Aircraft Noise

    PubMed Central

    Hede, Andrew J.

    2017-01-01

    Aim: This paper investigates whether mindfulness-based interventions might ameliorate the detrimental health effects of aircraft noise on residential communities. Review: Numerous empirical studies over the past 50 years have demonstrated the increasing negative impact of aircraft noise on residents worldwide. However, extensive database searches have revealed no published studies on psychological interventions that reduce residents’ reactivity to environmental noise. By contrast, there has been extensive research over several decades confirming the effectiveness of mindfulness-based stress reduction training in lowering people’s stress from work and life. Considering that stress is a major component of aircraft noise reaction, it would seem worth assessing whether mindfulness-based interventions might be effective in reducing the health effects of aircraft noise. It appears that no existing conceptualization of mindfulness specifically accounts for noise as a stressor. Conceptual Analysis: A new conceptual model is presented here which explains how mindfulness can reduce noise reactivity. Two types of mindfulness are distinguished: an active form (meta-mindfulness) and a passive form (supra-mindfulness). It is posited that meta-mindfulness can facilitate “cognitive defusion” which research has confirmed as enabling people to disconnect from their own dysfunctional thoughts. In the case of aircraft noise, negative thinking associated with residents’ reactive experiences can exacerbate the health effects they suffer. The present model further proposes that supra-mindfulness can enable an individual to disengage their own sense of identity from the often overwhelming negative thoughts which can define their existence when they are consumed by extreme noise annoyance. Conclusion: The mindfulness processes of defusion and disidentification are postulated to be the key efficacy mechanisms potentially responsible for reducing reactivity to aircraft noise. This

  10. Effects of N-acetylcysteine on noise-induced temporary threshold shift and temporary emission shift

    NASA Astrophysics Data System (ADS)

    Robinette, Martin

    2001-05-01

    Animal research has shown that antioxidants can provide significant protection to the cochlea from traumatic noise exposure with some benefit when given after the exposure. Similar results in humans would have a significant impact on both prevention and treatment of noise-induced hearing loss. The current study evaluates the effectiveness of N-acetylcysteine (NAC) on temporary threshold shift (TTS) by using both behavioral and physiological measures. Sixteen healthy, normal-hearing subjects were given NAC or a placebo prior to exposure to a 10-min, 102-dB narrow-band noise, centered at 2 kHz. This exposure was designed to induce a 10-15-dB TTS. Following the noise exposure, pure-tone thresholds (Bekesy) and transient-evoked otoacoustic emissions (TEOAE) were measured for 60 min to monitor the effects of NAC on TTS recovery. Postexposure measures were compared to baseline data. [Work supported by American BioHealth Group.

  11. Effects of N-acetylcysteine on noise-induced temporary threshold shift and temporary emission shift

    NASA Astrophysics Data System (ADS)

    Robinette, Martin

    2004-05-01

    Animal research has shown that antioxidants can provide significant protection to the cochlea from traumatic noise exposure with some benefit when given after the exposure. Similar results in humans would have a significant impact on both prevention and treatment of noise-induced hearing loss. The current study evaluates the effectiveness of N-acetylcysteine (NAC) on temporary threshold shift (TTS) by using both behavioral and physiological measures. Sixteen healthy, normal-hearing subjects were given NAC or a placebo prior to exposure to a 10-min, 102-dB narrow-band noise, centered at 2 kHz. This exposure was designed to induce a 10-15-dB TTS. Following the noise exposure, pure-tone thresholds (Bekesy) and transient-evoked otoacoustic emissions (TEOAE) were measured for 60 min to monitor the effects of NAC on TTS recovery. Postexposure measures were compared to baseline data. [Work supported by American BioHealth Group.

  12. Reduced In-Plane, Low Frequency Noise of an Active Flap Rotor

    DTIC Science & Technology

    2009-05-01

    decibels at a moderate airspeed, level flight condition at advance ratio of 0.30. Reduced noise levels were attributed to selective active flap schedules...that modified in-plane blade airloads on the advancing side of the rotor, generating counter-acting acoustic pulses that partially offset the negative...by up to 6 decibels at a moderate airspeed, level flight condition at advance ratio of 0.30. Reduced noise levels were attributed to selective active

  13. Fast random number generation with spontaneous emission noise of a single-mode semiconductor laser

    NASA Astrophysics Data System (ADS)

    Zhang, Jianzhong; Zhang, Mingjiang; Liu, Yi; Li, Pu; Yi, Xiaogang; Zhang, Mingtao; Wang, Yuncai

    2016-11-01

    We experimentally demonstrate a 12.5 Gb s-1 random number generator based on measuring the spontaneous emission noise of a single-mode semiconductor laser. The spontaneous emission of light is quantum mechanical in nature and is an inborn physical entropy source of true randomness. By combining a high-speed analog-to-digital converter and off-line processing, random numbers are extracted from the spontaneous emission with the verified randomness. The generator is simple, robust, and with no need of accurately tuning the comparison threshold. The use of semiconductor lasers makes it particularly compatible with the delivery of random numbers in optical networks.

  14. Noise Mitigation During Pile Driving Efficiently Reduces Disturbance of Marine Mammals.

    PubMed

    Nehls, Georg; Rose, Armin; Diederichs, Ansgar; Bellmann, Michael; Pehlke, Hendrik

    2016-01-01

    Acoustic monitoring of harbor porpoises (Phocoena phocoena L., 1758) indicated a strongly reduced disturbance by noise emitted by pile driving for offshore wind turbine foundations insulated by a big bubble curtain (BBC). This newly developed noise mitigation system was tested during construction of the offshore wind farm Borkum West II (North Sea). Because porpoise activity strongly corresponded to the sound level, operation of the new system under its most suitable configuration reduced the porpoise disturbance area by ~90%. Hence, for the first time, a positive effect of a noise mitigation system during offshore pile driving on an affected marine mammal species could be demonstrated.

  15. Dietary adipic acid reduces ammonia emission from swine excreta.

    PubMed

    van Kempen, T A

    2001-09-01

    Adipic acid is only partially catabolized when it is fed to animals, and a portion of it is excreted in urine. The excreted portion may lower urinary pH and, as a result, ammonia emission. The present study tested this hypothesis. In Exp. 1, nursery pigs (n = 14) were fed (for a period of 7 d) either a standard nursery diet or the same diet supplemented with 1% adipic acid to assess effects on urinary pH (collected on d 5 or 6) and in vitro ammonia emission from the collected urine samples that were mixed with control feces. In Exp. 2, grower pigs housed 10 each in one of two chambers were fed a control diet or the same diet supplemented with 1% adipic acid. Ventilated air was quantified and analyzed for ammonia using Fourier transform infrared spectroscopy to determine the effects of feeding 1% adipic acid on ammonia emission. The results from Exp. 1 showed that adipic acid strongly reduced urinary pH (from 7.7 to 5.5, P < 0.05). In vitro ammonia emission from these urine samples was significantly reduced at all the time points evaluated (1, 3, 18, and 46 h with reductions of 94, 93, 70, and 39%, respectively, P < 0.05). Experiment 2 showed that adipic acid supplementation reduced ammonia emission by 25% (P < 0.05), which corresponded to the predicted reduction in ammonia emission based on the reduction in manure pH observed. In conclusion, feeding adipic acid lowers urinary pH and reduces ammonia emission. The reduction in ammonia emission, though, does not correspond to the reduction in urinary pH but corresponds to the reduction in fecal pH as a result of mixing the urine and feces, in which feces act as a strong buffer.

  16. Acoustic Noise Induces Attention Shifts and Reduces Foraging Performance in Three-Spined Sticklebacks (Gasterosteus aculeatus)

    PubMed Central

    Purser, Julia; Radford, Andrew N.

    2011-01-01

    Acoustic noise is known to have a variety of detrimental effects on many animals, including humans, but surprisingly little is known about its impacts on foraging behaviour, despite the obvious potential consequences for survival and reproductive success. We therefore exposed captive three-spined sticklebacks (Gasterosteus aculeatus) to brief and prolonged noise to investigate how foraging performance is affected by the addition of acoustic noise to an otherwise quiet environment. The addition of noise induced only mild fear-related behaviours - there was an increase in startle responses, but no change in the time spent freezing or hiding compared to a silent control - and thus had no significant impact on the total amount of food eaten. However, there was strong evidence that the addition of noise increased food-handling errors and reduced discrimination between food and non-food items, results that are consistent with a shift in attention. Consequently, noise resulted in decreased foraging efficiency, with more attacks needed to consume the same number of prey items. Our results suggest that acoustic noise has the potential to influence a whole host of everyday activities through effects on attention, and that even very brief noise exposure can cause functionally significant impacts, emphasising the threat posed by ever-increasing levels of anthropogenic noise in the environment. PMID:21386909

  17. Longitudinal annoyance responses to a road traffic noise management strategy that reduced heavy vehicles at night.

    PubMed

    Brown, A L

    2015-01-01

    A traffic management strategy was designed to reduce trucks using an urban corridor. The intervention had potential to affect night-time truck flows, but did not target truck traffic in the day, or vehicles other than trucks at any hour. A two-year long panel study measured the community's response to this intervention, using five repeated measurements of response. There were significant reductions in the panel's response to noise, both for night-time annoyance and for interference with activities. This was remarkable given that noise monitoring showed that the intervention produced no change in conventional traffic noise indicators. However, there were measureable changes in the number of articulated truck movements at night, and the benefit can be attributed to reduction in the number of noise events from heavy vehicles. The parallel tracking of changes in reported noise effects and the numbers of heavy vehicles in the night hours in this longitudinal study provides strong support to the notion that noise effects at night depend on the number of noise events experienced, not only on the overall level of traffic noise. The latter appear to be unresponsive indicators by which to assess the noise-effect benefit of heavy vehicle reduction strategies.

  18. A new algorithm to reduce noise in microscopy images implemented with a simple program in python.

    PubMed

    Papini, Alessio

    2012-03-01

    All microscopical images contain noise, increasing when (e.g., transmission electron microscope or light microscope) approaching the resolution limit. Many methods are available to reduce noise. One of the most commonly used is image averaging. We propose here to use the mode of pixel values. Simple Python programs process a given number of images, recorded consecutively from the same subject. The programs calculate the mode of the pixel values in a given position (a, b). The result is a new image containing in (a, b) the mode of the values. Therefore, the final pixel value corresponds to that read in at least two of the pixels in position (a, b). The application of the program on a set of images obtained by applying salt and pepper noise and GIMP hurl noise with 10-90% standard deviation showed that the mode performs better than averaging with three-eight images. The data suggest that the mode would be more efficient (in the sense of a lower number of recorded images to process to reduce noise below a given limit) for lower number of total noisy pixels and high standard deviation (as impulse noise and salt and pepper noise), while averaging would be more efficient when the number of varying pixels is high, and the standard deviation is low, as in many cases of Gaussian noise affected images. The two methods may be used serially. Copyright © 2011 Wiley Periodicals, Inc.

  19. Noise reducing screen devices for in-flow pressure sensors

    NASA Technical Reports Server (NTRS)

    Schmitz, Fredric (Inventor); Liu, Sandy (Inventor); Jaeger, Stephen (Inventor); Horne, W. Clifton (Inventor)

    1997-01-01

    An acoustic sensor assembly is provided for sensing acoustic signals in a moving fluid such as high speed fluid stream. The assembly includes one or more acoustic sensors and a porous, acoustically transparent screen supported between the moving fluid stream and the sensor and having a major surface disposed so as to be tangent to the moving fluid. A layer of reduced velocity fluid separating the sensor from the porous screen. This reduced velocity fluid can comprise substantially still air. A foam filler material attenuates acoustic signals arriving at the assembly from other than a predetermined range of incident angles.

  20. Effect of natural compounds on reducing formaldehyde emission from plywood

    NASA Astrophysics Data System (ADS)

    Uchiyama, Shigehisa; Matsushima, Erica; Kitao, Nahoko; Tokunaga, Hiroshi; Ando, Masanori; Otsubo, Yasufumi

    The effects of natural compounds on reducing formaldehyde emission from plywood were investigated. Urea, catechin and vanillin were examined as the natural formaldehyde reducers. The microemission cell, with an internal volume of 35 ml, the maximum exposed test surface area of 177 cm 2 and an air purge flow rate of 50 ml min -1, was used to measure specific emission rate (SER). In the case of no reducer treatment, formaldehyde emission from plywood was fast and SERs were 4.4 mg m -2 h -1 at 30 °C and 15 mg m -2 h -1 at 60 °C. When this plywood was treated with the natural compounds, the SERs of formaldehyde were decreased at all temperatures. In the case of urea treatment, the SERs of formaldehyde decreased to 0.30 mg m -2 h -1 at 30 °C and 0.65 mg m -2 h -1 at 60 °C. When the urea treatment was applied to the inside of kitchen cabinet (made from plywood; 270 cm wide, 60 cm deep, 250 cm high), the concentration of formaldehyde was reduced substantially from 1600 to 130 μg m -3. The reducing effect of formaldehyde continued during the observation period (6 months), with a mean concentration of 100 μg m -3. Reducers in the plywood would react with released formaldehyde. Application of natural compounds such as urea, catechin and vanillin could provide a simple and effective approach for suppressing formaldehyde emission from plywood.

  1. Design and test of aircraft engine isolators for reduced interior noise

    NASA Technical Reports Server (NTRS)

    Unruh, J. F.; Scheidt, D. C.

    1982-01-01

    Improved engine vibration isolation was proposed to be the most weight and cost efficient retrofit structure-borne noise control measure for single engine general aviation aircraft. A study was carried out the objectives: (1) to develop an engine isolator design specification for reduced interior noise transmission, (2) select/design candidate isolators to meet a 15 dB noise reduction design goal, and (3) carry out a proof of concept evaluation test. Analytical model of the engine, vibration isolators and engine mount structure were coupled to an empirical model of the fuselage for noise transmission evaluation. The model was used to develop engine isolator dynamic properties design specification for reduced noise transmission. Candidate isolators ere chosen from available product literature and retrofit to a test aircraft. A laboratory based test procedure was then developed to simulate engine induced noise transmission in the aircraft for a proof of concept evaluation test. Three candidate isolator configurations were evaluated for reduced structure-borne noise transmission relative to the original equipment isolators.

  2. Reducing Greenhouse Gas Emissions from Agricultural Wetlands in Borneo

    NASA Astrophysics Data System (ADS)

    Abdul, H.; Fatah, L.; Nursyamsi, D.; Kazuyuki, I.

    2011-12-01

    At the forum G20 meeting in 2009, Indonesian President delivered Indonesia's commitment to reduce national greenhouse gas (GHG) emissions by 26% in 2020 by unilateral action and by 41% with support of other countries. To achieve the target, Indonesian government has put forestry, agriculture (including peatlands), energy, industry and transportation as main responsible sectors. Development of crop with low GHG emissions, increasing C sequestration and the use of organic fertilizers are among the activities to be carried out in 2010-2020 period to minimize GHG emissions from agricultural sectors. Three experiments have been carried out to elucidate the reflectivity of crop selection, soil ameliorants and organic fertilizers on GHG emissions from agricultural wetlands in Borneo. Firstly, gas samples were collected in weekly basis from oil palm, paddy, and vegetables fields and analyzed for methane (CH4) and nitrous oxide (N2O) concentrations by a gas chromatography. Secondly, coal fly ash, dolomite and ZnSO4 were incorporated into a pot containing peat and/or alluvial soils taken from wetlands in South Kalimantan. The air samples were taken and analyzed for CH4 by a gas chromatography. Finally, microbial consortium are isolated from soil, sediment and cow dung. The microbes were then propagated and used in a rice straw composting processes. The CO2, CH4 and N2O emissions from composting vessel were measured at one, two and four weeks of composting processes. The results showed that shifting the use of peatlands for oil palm to vegetable field reduced the GHG emissions by about 74% and that to paddy field reduce the GHG emissions by about 82%. The CH4 emissions from paddy field can be further reduced by applying dolomite. However, the use of coal fly ash and ZnSO4 increased CH4 emissions from peat soil cultivated to rice. The use of microbe isolated from saline soil could reduce GHG emissions during the composting of rice straw. The social aspect of GHG reduction in

  3. Reducing dust emissions at OAO Alchevskkoks coke battery 10A

    SciTech Connect

    T.F. Trembach; E.N. Lanina

    2009-07-15

    Coke battery 10A with rammed batch is under construction at OAO Alchevskkoks. The design documentation developed by Giprokoks includes measures for reducing dust emissions to the atmosphere. Aspiration systems with dry dust trapping are employed in the new components of coke battery 10A and in the existing coke-sorting equipment. Two-stage purification of dusty air in cyclones and bag filters is employed for the coke-sorting equipment. This system considerably reduces coke-dust emissions to the atmosphere.

  4. Recovery of otoacoustic emissions after high-level noise exposure in the American bullfrog

    PubMed Central

    Simmons, Dwayne D.; Lohr, Rachel; Wotring, Helena; Burton, Miriam D.; Hooper, Rebecca A.; Baird, Richard A.

    2014-01-01

    The American bullfrog (Rana catesbeiana) has an amphibian papilla (AP) that senses airborne, low-frequency sound and generates distortion product otoacoustic emissions (DPOAEs) similar to other vertebrate species. Although ranid frogs are typically found in noisy environments, the effects of noise on the AP have not been studied. First, we determined the noise levels that diminished DPOAE at 2f1–f2 using an f2 stimulus level at 80 dB SPL and that also produced morphological damage of the sensory epithelium. Second, we compared DPOAE (2f1–f2) responses with histopathologic changes occurring in bullfrogs after noise exposure. Consistent morphological damage, such as fragmented hair cells and missing bundles, as well as elimination of DPOAE responses were seen only after very high-level (>150 dB SPL) sound exposures. The morphological response of hair cells to noise differed along the mediolateral AP axis: medial hair cells were sensitive to noise and lateral hair cells were relatively insensitive to noise. Renewed or repaired hair cells were not observed until 9 days post-exposure. Following noise exposure, DPOAE responses disappeared within 24 h and then recovered to normal pre-exposure levels within 3–4 days. Our results suggest that DPOAEs in the bullfrog are sensitive to the initial period of hair cell damage. After noise-induced damage, the bullfrog AP has functional recovery mechanisms that do not depend on substantial hair cell regeneration or repair. Thus, the bullfrog auditory system might serve as an interesting model for investigation of ways to prevent noise damage. PMID:24501139

  5. Leading edge serrations which reduce the noise of low-speed rotors

    NASA Technical Reports Server (NTRS)

    Soderman, P. T.

    1973-01-01

    Acoustic effects of serrated brass strips attached near the leading edges of two different size rotors were investigated. The two bladed rotors were tested in hover. Rotor rotational speed, blade angle, serration shape, and serration position were varied. The serrations were more effective as noise suppressors at rotor tip speeds less than 135 m/sec (444 ft/sec) than at higher speeds. high frequency noise was reduced but the low frequency rotational noise was little affected. Noise reductions from 4 to 8 db overall sound pressure level and 3 to 17 db in the upper octave bands were achieved on the 1.52 m (5.0 ft) diameter rotor. Noise reductions up to 4 db overall sound pressure level were measured for the 2.59 m (8.5 ft) diameter rotor at some conditions.

  6. Reducing transit bus emissions: Alternative fuels or traffic operations?

    NASA Astrophysics Data System (ADS)

    Alam, Ahsan; Hatzopoulou, Marianne

    2014-06-01

    In this study, we simulated the operations and greenhouse gas (GHG) emissions of transit buses along a busy corridor and quantified the effects of two different fuels (conventional diesel and compressed natural gas) as well as a set of driving conditions on emissions. Results indicate that compressed natural gas (CNG) reduces GHG emissions by 8-12% compared to conventional diesel, this reduction could increase to 16% with high levels of traffic congestion. However, the benefits of switching from conventional diesel to CNG are less apparent when the road network is uncongested. We also investigated the effects of bus operations on emissions by applying several strategies such as transit signal priority (TSP), queue jumper lanes, and relocation of bus stops. Results show that in congested conditions, TSP alone can reduce GHG emissions by 14% and when combined with improved technology; a reduction of 23% is achieved. The reduction benefits are even more apparent when other transit operational improvements are combined with TSP. Finally a sensitivity analysis was performed to investigate the effect of operational improvements on emissions under varying levels of network congestion. We observe that under “extreme congestion”, the benefits of TSP decrease.

  7. Cost-effectiveness of reducing sulfur emissions from ships.

    PubMed

    Wang, Chengfeng; Corbett, James J; Winebrake, James J

    2007-12-15

    We model cost-effectiveness of control strategies for reducing SO2 emissions from U.S. foreign commerce ships traveling in existing European or hypothetical U.S. West Coast SO(x) Emission Control Areas (SECAs) under international maritime regulations. Variation among marginal costs of control for individual ships choosing between fuel-switching and aftertreatment reveals cost-saving potential of economic incentive instruments. Compared to regulations prescribing low sulfur fuels, a performance-based policy can save up to $260 million for these ships with 80% more emission reductions than required because least-cost options on some individual ships outperform standards. Optimal simulation of a market-based SO2 control policy for approximately 4,700 U.S. foreign commerce ships traveling in the SECAs in 2002 shows that SECA emissions control targets can be achieved by scrubbing exhaust gas of one out of ten ships with annual savings up to $480 million over performance-based policy. A market-based policy could save the fleet approximately $63 million annually under our best-estimate scenario. Spatial evaluation of ship emissions reductions shows that market-based instruments can reduce more SO2 closer to land while being more cost-effective for the fleet. Results suggest that combining performance requirements with market-based instruments can most effectively control SO2 emissions from ships.

  8. Reducing GHG emissions in rice systems: Opportunities and challenges

    NASA Astrophysics Data System (ADS)

    Linquist, B.

    2014-12-01

    Agriculture is faced with the challenge of providing healthy food for a growing population at minimal environmental cost. Rice (Oryza sativa), the staple crop for the largest number of people on earth, is grown under flooded soil conditions has higher greenhouse gas (GHG) emissions than most crops. This is primarily due to high methane emissions. In this talk I will focus on recent work and reviews on efforts to reduce GHG emissions from rice systems while at the same time maintaining or increasing the productivity of these systems. Specifically, the role of water, straw and nutrient management will be discussed. A great deal of research has gone into evaluating alternate-wetting and drying (AWD) irrigation management. AWD has tremendous potential to reduce GHG emissions; however I will examine how it needs to be practiced to achieve these goals, as well as limitations to its use such as where it can be practiced and possible effects on soil C. Straw management is critical as it provides a key carbon source for methanogens. Straw, however, is difficult to manage and has limited alternative uses. Various forms of nutrient management have also been proposed to reduced GHG emissions in rice systems. I will provide an overview of these and discuss their potential.

  9. Maintaining reduced noise levels in a resource-constrained neonatal intensive care unit by operant conditioning.

    PubMed

    Ramesh, A; Denzil, S B; Linda, R; Josephine, P K; Nagapoornima, M; Suman Rao, P N; Swarna Rekha, A

    2013-03-01

    To evaluate the efficacy of operant conditioning in sustaining reduced noise levels in the neonatal intensive care unit (NICU). Quasi-experimental study on quality of care. Level III NICU of a teaching hospital in south India. 26 staff employed in the NICU. (7 Doctors, 13 Nursing staff and 6 Nursing assistants). Operant conditioning of staff activity for 6 months. This method involves positive and negative reinforcement to condition the staff to modify noise generating activities. Comparing noise levels in decibel: A weighted [dB (A)] before conditioning with levels at 18 and 24 months after conditioning. Decibel: A weighted accounts for noise that is audible to human ears. Operant conditioning for 6 months sustains the reduced noise levels to within 62 dB in ventilator room 95% CI: 60.4 - 62.2 and isolation room (95% CI: 55.8 - 61.5). In the preterm room, noise can be maintained within 52 dB (95% CI: 50.8 - 52.6). This effect is statistically significant in all the rooms at 18 months (P = 0.001). At 24 months post conditioning there is a significant rebound of noise levels by 8.6, 6.7 and 9.9 dB in the ventilator, isolation and preterm room, respectively (P =0.001). Operant conditioning for 6 months was effective in sustaining reduced noise levels. At 18 months post conditioning, the noise levels were maintained within 62 dB (A), 60 dB (A) and 52 dB (A) in the ventilator, isolation and pre-term room, respectively. Conditioning needs to be repeated at 12 months in the ventilator room and at 18 months in the other rooms.

  10. The Physical Mechanism for Retinal Discrete Dark Noise: Thermal Activation or Cellular Ultraweak Photon Emission?

    PubMed Central

    Salari, Vahid; Scholkmann, Felix; Bokkon, Istvan; Shahbazi, Farhad; Tuszynski, Jack

    2016-01-01

    For several decades the physical mechanism underlying discrete dark noise of photoreceptors in the eye has remained highly controversial and poorly understood. It is known that the Arrhenius equation, which is based on the Boltzmann distribution for thermal activation, can model only a part (e.g. half of the activation energy) of the retinal dark noise experimentally observed for vertebrate rod and cone pigments. Using the Hinshelwood distribution instead of the Boltzmann distribution in the Arrhenius equation has been proposed as a solution to the problem. Here, we show that the using the Hinshelwood distribution does not solve the problem completely. As the discrete components of noise are indistinguishable in shape and duration from those produced by real photon induced photo-isomerization, the retinal discrete dark noise is most likely due to ‘internal photons’ inside cells and not due to thermal activation of visual pigments. Indeed, all living cells exhibit spontaneous ultraweak photon emission (UPE), mainly in the optical wavelength range, i.e., 350–700 nm. We show here that the retinal discrete dark noise has a similar rate as UPE and therefore dark noise is most likely due to spontaneous cellular UPE and not due to thermal activation. PMID:26950936

  11. Suppression of fiber modal noise induced radial velocity errors for bright emission-line calibration sources

    SciTech Connect

    Mahadevan, Suvrath; Halverson, Samuel; Ramsey, Lawrence; Venditti, Nick

    2014-05-01

    Modal noise in optical fibers imposes limits on the signal-to-noise ratio (S/N) and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high S/N. Many of these spectrographs plan to use highly coherent emission-line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial-mass planets. These high-precision calibration sources often use single-mode fibers or highly coherent sources. Coupling light from single-mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to spectrograph calibration systems. Our solution uses an integrating sphere in conjunction with a diffuser that is moved rapidly using electrostrictive polymers, and is generally superior to most tested forms of mechanical fiber agitation. We demonstrate a high level of modal noise reduction with a narrow bandwidth 1550 nm laser. Our relatively inexpensive solution immediately enables spectrographs to take advantage of the innate precision of bright state-of-the art calibration sources by removing a major source of systematic noise.

  12. The Physical Mechanism for Retinal Discrete Dark Noise: Thermal Activation or Cellular Ultraweak Photon Emission?

    PubMed

    Salari, Vahid; Scholkmann, Felix; Bokkon, Istvan; Shahbazi, Farhad; Tuszynski, Jack

    2016-01-01

    For several decades the physical mechanism underlying discrete dark noise of photoreceptors in the eye has remained highly controversial and poorly understood. It is known that the Arrhenius equation, which is based on the Boltzmann distribution for thermal activation, can model only a part (e.g. half of the activation energy) of the retinal dark noise experimentally observed for vertebrate rod and cone pigments. Using the Hinshelwood distribution instead of the Boltzmann distribution in the Arrhenius equation has been proposed as a solution to the problem. Here, we show that the using the Hinshelwood distribution does not solve the problem completely. As the discrete components of noise are indistinguishable in shape and duration from those produced by real photon induced photo-isomerization, the retinal discrete dark noise is most likely due to 'internal photons' inside cells and not due to thermal activation of visual pigments. Indeed, all living cells exhibit spontaneous ultraweak photon emission (UPE), mainly in the optical wavelength range, i.e., 350-700 nm. We show here that the retinal discrete dark noise has a similar rate as UPE and therefore dark noise is most likely due to spontaneous cellular UPE and not due to thermal activation.

  13. Reducing image noise in computed tomography (CT) colonography: effect of an integrated circuit CT detector.

    PubMed

    Liu, Yu; Leng, Shuai; Michalak, Gregory J; Vrieze, Thomas J; Duan, Xinhui; Qu, Mingliang; Shiung, Maria M; McCollough, Cynthia H; Fletcher, Joel G

    2014-01-01

    To investigate whether the integrated circuit (IC) detector results in reduced noise in computed tomography (CT) colonography (CTC). Three hundred sixty-six consecutive patients underwent clinically indicated CTC using the same CT scanner system, except for a difference in CT detectors (IC or conventional). Image noise, patient size, and scanner radiation output (volume CT dose index) were quantitatively compared between patient cohorts using each detector system, with separate comparisons for the abdomen and pelvis. For the abdomen and pelvis, despite significantly larger patient sizes in the IC detector cohort (both P < 0.001), image noise was significantly lower (both P < 0.001), whereas volume CT dose index was unchanged (both P > 0.18). Based on the observed image noise reduction, radiation dose could alternatively be reduced by approximately 20% to result in similar levels of image noise. Computed tomography colonography images acquired using the IC detector had significantly lower noise than images acquired using the conventional detector. This noise reduction can permit further radiation dose reduction in CTC.

  14. Plant factory: A new method for reducing carbon emissions

    NASA Astrophysics Data System (ADS)

    Zhang, Rong; Liu, Tong; Ma, Jianshe

    2017-03-01

    In recent years, climate change has become a focus issue all over the world. Many scientific studies have confirmed the relationship between the emission of greenhouse gas such as carbon dioxide and global climate change. Reducing the emission of greenhouse gas is an effective way to solve the problem of climate change. This paper presents a new method for reducing carbon emissions: using the photosynthesis of plants to achieve carbon fixation in plant factory. In order to verify the feasibility of this method, we built a closed artificial light plant factory adopting LED lighting to conduct the experiment of carbon dioxide enrichment. The results shows that the production of the plants increased by 20%-25% and the plants fixed a considerable amount of carbon dioxide by increasing the concentration of carbon dioxide in the environment to 1000 ppm.

  15. Semiconductor technology for reducing emissions and increasing efficiency

    SciTech Connect

    Duffin, B.; Frank, R.

    1997-12-31

    The cooperation and support of all industries are required to significantly impact a worldwide reduction in gaseous emissions that may contribute to climate change. Each industry also is striving to more efficiently utilize the resources that it consumes since this is both conservation for good citizenship and an intelligent approach to business. The semiconductor industry is also extremely concerned with these issues. However, semiconductor manufacturer`s products provide solutions for reduced emissions and increased efficiency in their industry, other industries and areas that can realize significant improvements through control technology. This paper will focus on semiconductor technologies of digital control, power switching and sensing to improve efficiency and reduce emissions in automotive, industrial, and office/home applications. 10 refs., 13 figs.

  16. Wellbeing impacts of city policies for reducing greenhouse gas emissions.

    PubMed

    Hiscock, Rosemary; Mudu, Pierpaolo; Braubach, Matthias; Martuzzi, Marco; Perez, Laura; Sabel, Clive

    2014-11-28

    To mitigate climate change, city authorities are developing policies in areas such as transportation, housing and energy use, to reduce greenhouse gas emissions. In addition to their effects on greenhouse gas emissions, these policies are likely to have consequences for the wellbeing of their populations for example through changes in opportunities to take physical exercise. In order to explore the potential consequences for wellbeing, we first explore what 'wellbeing' is and how it can be operationalised for urban planners. In this paper, we illustrate how wellbeing can be divided into objective and subjective aspects which can be measured quantitatively; our review of measures informs the development of a theoretical model linking wellbeing to policies which cities use to reduce greenhouse gas emissions. Finally, we discuss the extent to which the links proposed in the conceptual model are supported by the literature and how cities can assess wellbeing implications of policies.

  17. Wellbeing Impacts of City Policies for Reducing Greenhouse Gas Emissions

    PubMed Central

    Hiscock, Rosemary; Mudu, Pierpaolo; Braubach, Matthias; Martuzzi, Marco; Perez, Laura; Sabel, Clive

    2014-01-01

    To mitigate climate change, city authorities are developing policies in areas such as transportation, housing and energy use, to reduce greenhouse gas emissions. In addition to their effects on greenhouse gas emissions, these policies are likely to have consequences for the wellbeing of their populations for example through changes in opportunities to take physical exercise. In order to explore the potential consequences for wellbeing, we first explore what ‘wellbeing’ is and how it can be operationalized for urban planners. In this paper, we illustrate how wellbeing can be divided into objective and subjective aspects which can be measured quantitatively; our review of measures informs the development of a theoretical model linking wellbeing to policies which cities use to reduce greenhouse gas emissions. Finally, we discuss the extent to which the links proposed in the conceptual model are supported by the literature and how cities can assess wellbeing implications of policies. PMID:25464129

  18. Reducing the noise emanating from a twin jet nozzle using flexible filaments

    NASA Astrophysics Data System (ADS)

    Lucas, Nathaniel; Doty, Michael; Taubert, Lutz; Wygnanski, Israel

    2013-04-01

    A twin jet was tested in anechoic facilities at the University of Arizona and NASA Langley Research Center to determine the effectiveness of flexible filaments in jet noise reduction. Results were strongly dependent on filament diameter and material, the most effective of which was found to be Tex 800 Kevlar. In the best configurations, the filaments consistently eliminated screech tones and reduced overall sound pressure level by 3 dB or more. Additionally, broadband shock noise was diminished by more than 5 dB over certain audible frequency ranges. Larger-scale tests run at NASA showed comparable reductions in overall sound pressure level and broadband shock-associated noise.

  19. Paired carriers as a way to reduce quantum noise of multicarrier gravitational-wave detectors

    NASA Astrophysics Data System (ADS)

    Korobko, Mikhail; Voronchev, Nikita; Miao, Haixing; Khalili, Farid Ya.

    2015-02-01

    We explore new regimes of laser interferometric gravitational-wave detectors with multiple optical carriers which allow us to reduce the quantum noise of these detectors. In particular, we show that using two carriers with the opposite detunings, homodyne angles, and squeezing angles, but identical other parameters (the antisymmetric carriers), one can suppress the quantum noise in such a way that its spectrum follows the Standard Quantum Limit (SQL) at low frequencies. Relaxing this antisymmetry condition, it is also possible to slightly overcome the SQL in broadband. Combining several such pairs in the xylophone configuration, it is possible to shape the quantum noise spectrum flexibly.

  20. Structuring economic incentives to reduce emissions from deforestation within Indonesia.

    PubMed

    Busch, Jonah; Lubowski, Ruben N; Godoy, Fabiano; Steininger, Marc; Yusuf, Arief A; Austin, Kemen; Hewson, Jenny; Juhn, Daniel; Farid, Muhammad; Boltz, Frederick

    2012-01-24

    We estimate and map the impacts that alternative national and subnational economic incentive structures for reducing emissions from deforestation (REDD+) in Indonesia would have had on greenhouse gas emissions and national and local revenue if they had been in place from 2000 to 2005. The impact of carbon payments on deforestation is calibrated econometrically from the pattern of observed deforestation and spatial variation in the benefits and costs of converting land to agriculture over that time period. We estimate that at an international carbon price of $10/tCO(2)e, a "mandatory incentive structure," such as a cap-and-trade or symmetric tax-and-subsidy program, would have reduced emissions by 163-247 MtCO(2)e/y (20-31% below the without-REDD+ reference scenario), while generating a programmatic budget surplus. In contrast, a "basic voluntary incentive structure" modeled after a standard payment-for-environmental-services program would have reduced emissions nationally by only 45-76 MtCO(2)e/y (6-9%), while generating a programmatic budget shortfall. By making four policy improvements--paying for net emission reductions at the scale of an entire district rather than site-by-site; paying for reductions relative to reference levels that match business-as-usual levels; sharing a portion of district-level revenues with the national government; and sharing a portion of the national government's responsibility for costs with districts--an "improved voluntary incentive structure" would have been nearly as effective as a mandatory incentive structure, reducing emissions by 136-207 MtCO(2)e/y (17-26%) and generating a programmatic budget surplus.

  1. Structuring economic incentives to reduce emissions from deforestation within Indonesia

    PubMed Central

    Busch, Jonah; Lubowski, Ruben N.; Godoy, Fabiano; Steininger, Marc; Yusuf, Arief A.; Austin, Kemen; Hewson, Jenny; Juhn, Daniel; Farid, Muhammad; Boltz, Frederick

    2012-01-01

    We estimate and map the impacts that alternative national and subnational economic incentive structures for reducing emissions from deforestation (REDD+) in Indonesia would have had on greenhouse gas emissions and national and local revenue if they had been in place from 2000 to 2005. The impact of carbon payments on deforestation is calibrated econometrically from the pattern of observed deforestation and spatial variation in the benefits and costs of converting land to agriculture over that time period. We estimate that at an international carbon price of $10/tCO2e, a “mandatory incentive structure,” such as a cap-and-trade or symmetric tax-and-subsidy program, would have reduced emissions by 163–247 MtCO2e/y (20–31% below the without-REDD+ reference scenario), while generating a programmatic budget surplus. In contrast, a “basic voluntary incentive structure” modeled after a standard payment-for-environmental-services program would have reduced emissions nationally by only 45–76 MtCO2e/y (6–9%), while generating a programmatic budget shortfall. By making four policy improvements—paying for net emission reductions at the scale of an entire district rather than site-by-site; paying for reductions relative to reference levels that match business-as-usual levels; sharing a portion of district-level revenues with the national government; and sharing a portion of the national government's responsibility for costs with districts—an “improved voluntary incentive structure” would have been nearly as effective as a mandatory incentive structure, reducing emissions by 136–207 MtCO2e/y (17–26%) and generating a programmatic budget surplus. PMID:22232665

  2. TRANSIENT SUPPRESSION PACKAGING FOR REDUCED EMISSIONS FROM ROTARY KILN INCINERATORS

    EPA Science Inventory

    Experiments were performed on a 73 kW rotary kiln incinerator simulator to determine whether innovative waste packaging designs might reduce transient emissions of products of incomplete combustion due to batch charging of containerized liquid surrogate waste compounds bound on g...

  3. Field tests on biochar to reduce emissions from soil fumigation

    USDA-ARS?s Scientific Manuscript database

    Soil fumigation continues to be one of the most important strategies for pest management in orchards. Although low permeability tarp such as totally impermeable film (TIF) has shown to be the most effective in reducing fumigant emissions, costs are high and tarp disposal is needed after use. The obj...

  4. TRANSIENT SUPPRESSION PACKAGING FOR REDUCED EMISSIONS FROM ROTARY KILN INCINERATORS

    EPA Science Inventory

    Experiments were performed on a 73 kW rotary kiln incinerator simulator to determine whether innovative waste packaging designs might reduce transient emissions of products of incomplete combustion due to batch charging of containerized liquid surrogate waste compounds bound on g...

  5. Heterogeneous Integration for Reduced Phase Noise and Improved Reliability of Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Srinivasan, Sudharsanan

    Significant savings in cost, power and space are possible in existing optical data transmission networks, sensors and metrology equipment through photonic integration. Photonic integration can be broadly classified into two categories, hybrid and monolithic integration. The former involves assembling multiple single functionality optical devices together into a single package including any optical coupling and/or electronic connections. On the other hand monolithic integration assembles many devices or optical functionalities on a single chip so that all the optical connections are on chip and require no external alignment. This provides a substantial improvement in reliability and simplifies testing. Monolithic integration has been demonstrated on both indium phosphide (InP) and silicon (Si) substrates. Integration on larger 300mm Si substrates can further bring down the cost and has been a major area of research in recent years. Furthermore, with increasing interest from industry, the hybrid silicon platform is emerging as a new technology for integrating various active and passive optical elements on a single chip. This is both in the interest of bringing down manufacturing cost through scaling along with continued improvement in performance and to produce multi-functional photonic integrated circuits (PIC). The goal of this work is twofold. First, we show four laser demonstrations that use the hybrid silicon platform to lower phase noise due to spontaneous emission, based on the following two techniques, viz. confinement factor reduction and negative optical feedback. The first two demonstrations are of mode-locked lasers and the next two are of tunable lasers. Some of the key results include; (a) 14dB white frequency noise reduction of a 20GHz radio-frequency (RF) signal from a harmonically mode-locked long cavity laser with greater than 55dB supermode noise suppression, (b) 8dB white frequency noise reduction from a colliding pulse mode-locked laser by

  6. Treatment with Piribedil and Memantine Reduces Noise-Induced Loss of Inner Hair Cell Synaptic Ribbons

    PubMed Central

    Altschuler, Richard A.; Wys, Noel; Prieskorn, Diane; Martin, Cathy; DeRemer, Susan; Bledsoe, Sanford; Miller, Josef M.

    2016-01-01

    Noise overstimulation can induce loss of synaptic ribbons associated with loss of Inner Hair Cell – Auditory Nerve synaptic connections. This study examined if systemic administration of Piribedil, a dopamine agonist that reduces the sound evoked auditory nerve compound action potential and/or Memantine, an NMDA receptor open channel blocker, would reduce noise-induced loss of Inner Hair Cell ribbons. Rats received systemic Memantine and/or Piribedil for 3 days before and 3 days after a 3 hour 4 kHz octave band noise at 117 dB (SPL). At 21 days following the noise there was a 26% and 38% loss of synaptic ribbons in regions 5.5 and 6.5 mm from apex, respectively, elevations in 4-, 8- and 20 kHz tonal ABR thresholds and reduced dynamic output at higher intensities of stimulation. Combined treatment with Piribedil and Memantine produced a significant reduction in the noise-induced loss of ribbons in both regions and changes in ABR sensitivity and dynamic responsiveness. Piribedil alone gave significant reduction in only the 5.5 mm region and Memantine alone did not reach significance in either region. Results identify treatments that could prevent the hearing loss and hearing disorders that result from noise-induced loss of Inner Hair Cell – Auditory Nerve synaptic connections. PMID:27686418

  7. Investigations of the electron phase space dynamics in triggered whistler wave emissions using low noise \\delta f method

    NASA Astrophysics Data System (ADS)

    Tao, Xin; Zonca, Fulvio; Chen, Liu

    2017-09-01

    The evolution of the electron phase space structures during excitation of a triggered emission is investigated using the nonlinear δ f method. Previous studies suggested that the dynamics of phase space structures due to nonlinear wave particle interactions is critical to the excitation of triggered emissions with frequency chirping. We introduce the use of the nonlinear δ f method to simulate triggered emissions. Compared with full-f particle-in-cell method, the nonlinear δ f method significantly reduces numerical noise, therefore making the phase space structures more identifiable. Specific to the simulation of triggered emissions, the nonlinear δ f method also does not show numerical distortion of the distribution function due to reflecting particle boundary conditions. Using the nonlinear δ f method, we show that during the main portion of the chirping element, the phase space structure roughly maintains a shape so that the resonant island moves a distance in phase space that is on the same order as its width during one phase space bounce period of deeply trapped particles, supporting that the interaction is non-adiabatic. We also demonstrate the disappearance of the phase space structure near the end of the chirping. Our work suggests that the nonlinear δ f method could be very useful for the study of excitation of triggered emissions and to understand the mechanism of frequency chirping.

  8. Hunting at the highway: traffic noise reduces foraging efficiency in acoustic predators.

    PubMed

    Siemers, Björn M; Schaub, Andrea

    2011-06-07

    Noise pollution from human traffic networks and industrial activity impacts vast areas of our planet. While anthropogenic noise effects on animal communication are well documented, we have very limited understanding of noise impact on more complex ecosystem processes, such as predator-prey interactions, albeit urgently needed to devise mitigation measures. Here, we show that traffic noise decreases the foraging efficiency of an acoustic predator, the greater mouse-eared bat (Myotis myotis). These bats feed on large, ground-running arthropods that they find by listening to their faint rustling sounds. We measured the bats' foraging performance on a continuous scale of acoustically simulated highway distances in a behavioural experiment, designed to rule out confounding factors such as general noise avoidance. Successful foraging bouts decreased and search time drastically increased with proximity to the highway. At 7.5 m to the road, search time was increased by a factor of five. From this increase, we predict a 25-fold decrease in surveyed ground area and thus in foraging efficiency for a wild bat. As most of the bats' prey are predators themselves, the noise impact on the bats' foraging performance will have complex effects on the food web and ultimately on the ecosystem stability. Similar scenarios apply to other ecologically important and highly protected acoustic predators, e.g. owls. Our study provides the empirical basis for quantitative predictions of anthropogenic noise impacts on ecosystem processes. It highlights that an understanding of the effects of noise emissions and other forms of 'sensory pollution' are crucially important for the assessment of environmental impact of human activities.

  9. Hunting at the highway: traffic noise reduces foraging efficiency in acoustic predators

    PubMed Central

    Siemers, Björn M.; Schaub, Andrea

    2011-01-01

    Noise pollution from human traffic networks and industrial activity impacts vast areas of our planet. While anthropogenic noise effects on animal communication are well documented, we have very limited understanding of noise impact on more complex ecosystem processes, such as predator–prey interactions, albeit urgently needed to devise mitigation measures. Here, we show that traffic noise decreases the foraging efficiency of an acoustic predator, the greater mouse-eared bat (Myotis myotis). These bats feed on large, ground-running arthropods that they find by listening to their faint rustling sounds. We measured the bats' foraging performance on a continuous scale of acoustically simulated highway distances in a behavioural experiment, designed to rule out confounding factors such as general noise avoidance. Successful foraging bouts decreased and search time drastically increased with proximity to the highway. At 7.5 m to the road, search time was increased by a factor of five. From this increase, we predict a 25-fold decrease in surveyed ground area and thus in foraging efficiency for a wild bat. As most of the bats' prey are predators themselves, the noise impact on the bats' foraging performance will have complex effects on the food web and ultimately on the ecosystem stability. Similar scenarios apply to other ecologically important and highly protected acoustic predators, e.g. owls. Our study provides the empirical basis for quantitative predictions of anthropogenic noise impacts on ecosystem processes. It highlights that an understanding of the effects of noise emissions and other forms of ‘sensory pollution’ are crucially important for the assessment of environmental impact of human activities. PMID:21084347

  10. Reduced In-Plane, Low Frequency Helicopter Noise of an Active Flap Rotor

    NASA Technical Reports Server (NTRS)

    Sim, Ben W.; Janakiram, Ram D.; Barbely, Natasha L.; Solis, Eduardo

    2009-01-01

    Results from a recent joint DARPA/Boeing/NASA/Army wind tunnel test demonstrated the ability to reduce in-plane, low frequency noise of the full-scale Boeing-SMART rotor using active flaps. Test data reported in this paper illustrated that acoustic energy in the first six blade-passing harmonics could be reduced by up to 6 decibels at a moderate airspeed, level flight condition corresponding to advance ratio of 0.30. Reduced noise levels were attributed to selective active flap schedules that modified in-plane blade airloads on the advancing side of the rotor, in a manner, which generated counteracting acoustic pulses that partially offset the negative pressure peaks associated with in-plane, steady thickness noise. These favorable reduced-noise operating states are a strong function of the active flap actuation amplitude, frequency and phase. The associated noise reductions resulted in reduced aural detection distance by up to 18%, but incurred significant vibratory load penalties due to increased hub shear forces. Small reductions in rotor lift-to-drag ratios, of no more than 3%, were also measured

  11. Temporal phase mask encrypted optical steganography carried by amplified spontaneous emission noise.

    PubMed

    Wu, Ben; Wang, Zhenxing; Shastri, Bhavin J; Chang, Matthew P; Frost, Nicholas A; Prucnal, Paul R

    2014-01-13

    A temporal phase mask encryption method is proposed and experimentally demonstrated to improve the security of the stealth channel in an optical steganography system. The stealth channel is protected in two levels. In the first level, the data is carried by amplified spontaneous emission (ASE) noise, which cannot be detected in either the time domain or spectral domain. In the second level, even if the eavesdropper suspects the existence of the stealth channel, each data bit is covered by a fast changing phase mask. The phase mask code is always combined with the wide band noise from ASE. Without knowing the right phase mask code to recover the stealth data, the eavesdropper can only receive the noise like signal with randomized phase.

  12. Indian oil company joins efforts to reduce methane emissions

    NASA Astrophysics Data System (ADS)

    Kumar, Mohi

    The Oil and Natural Gas Corp, Ltd. (ONGC), headquartered in Dehradun, India, has joined seven U.S. and Canadian oil and natural gas companies as a partner in a U.S. Environmental Protection Agency program to reduce greenhouse gas emissions. EPA's Natural Gas STAR International Program aims to reduce methane emissions from the oil and natural gas sector while delivering more gas to markets around the world. With this partnership, ONGC agrees to implement emissions reduction practices and to submit annual reports on progress achieved; EPA agrees to assist ONGC with training technicians in new cost-effective technologies that will help achieve target emissions. The Natural Gas STAR International Program is administered under the Methane to Markets Partnership, a group of 20 countries and 600 companies across the globe that since 2004 has volunteered to cut methane emissions. More information on EPA's agreement with ONGC can be found at http://www.epa.gov/gasstar/index.htm; information about the Methane to Markets Partnership can be found at http://www.methanetomarkets.org.

  13. Opportunities for reducing greenhouse gas emissions in tropical peatlands.

    PubMed

    Murdiyarso, D; Hergoualc'h, K; Verchot, L V

    2010-11-16

    The upcoming global mechanism for reducing emissions from deforestation and forest degradation in developing countries should include and prioritize tropical peatlands. Forested tropical peatlands in Southeast Asia are rapidly being converted into production systems by introducing perennial crops for lucrative agribusiness, such as oil-palm and pulpwood plantations, causing large greenhouse gas (GHG) emissions. The Intergovernmental Panel on Climate Change Guidelines for GHG Inventory on Agriculture, Forestry, and Other Land Uses provide an adequate framework for emissions inventories in these ecosystems; however, specific emission factors are needed for more accurate and cost-effective monitoring. The emissions are governed by complex biophysical processes, such as peat decomposition and compaction, nutrient availability, soil water content, and water table level, all of which are affected by management practices. We estimate that total carbon loss from converting peat swamp forests into oil palm is 59.4 ± 10.2 Mg of CO(2) per hectare per year during the first 25 y after land-use cover change, of which 61.6% arise from the peat. Of the total amount (1,486 ± 183 Mg of CO(2) per hectare over 25 y), 25% are released immediately from land-clearing fire. In order to maintain high palm-oil production, nitrogen inputs through fertilizer are needed and the magnitude of the resulting increased N(2)O emissions compared to CO(2) losses remains unclear.

  14. Opportunities for reducing greenhouse gas emissions in tropical peatlands

    PubMed Central

    Murdiyarso, D.; Hergoualc’h, K.; Verchot, L. V.

    2010-01-01

    The upcoming global mechanism for reducing emissions from deforestation and forest degradation in developing countries should include and prioritize tropical peatlands. Forested tropical peatlands in Southeast Asia are rapidly being converted into production systems by introducing perennial crops for lucrative agribusiness, such as oil-palm and pulpwood plantations, causing large greenhouse gas (GHG) emissions. The Intergovernmental Panel on Climate Change Guidelines for GHG Inventory on Agriculture, Forestry, and Other Land Uses provide an adequate framework for emissions inventories in these ecosystems; however, specific emission factors are needed for more accurate and cost-effective monitoring. The emissions are governed by complex biophysical processes, such as peat decomposition and compaction, nutrient availability, soil water content, and water table level, all of which are affected by management practices. We estimate that total carbon loss from converting peat swamp forests into oil palm is 59.4 ± 10.2 Mg of CO2 per hectare per year during the first 25 y after land-use cover change, of which 61.6% arise from the peat. Of the total amount (1,486 ± 183 Mg of CO2 per hectare over 25 y), 25% are released immediately from land-clearing fire. In order to maintain high palm-oil production, nitrogen inputs through fertilizer are needed and the magnitude of the resulting increased N2O emissions compared to CO2 losses remains unclear. PMID:21081702

  15. Optimization of gasoline hydrocarbon compositions for reducing exhaust emissions.

    PubMed

    Shen, Yitao; Shuai, Shijin; Wang, Jianxin; Xiao, Jianhua

    2009-01-01

    Effects of hydrocarbon compositions on raw exhaust emissions and combustion processes were studied on an engine test bench. The optimization of gasoline hydrocarbon composition was discussed. As olefins content increased from 10.0% to 25.0% in volume, the combustion duration was shortened by about 2 degree crank angle (degrees CA), and the engine-out THC emission was reduced by about 15%. On the other hand, as aromatics content changed from 35.0% to 45.0%, the engine-out NOx emissions increased by 4%. An increment in olefins content resulted in a slight increase in engine-out CO emission, while the aromatics content had little effect on engine-out total hydrocarbon (THC) and CO emissions. Over the new European driving cycle (NEDC), the THC, NOx and CO emissions of fuel with 25.0% olefins and 35.0% aromatics were about 45%, 21% and 19% lower than those of fuel with 10.0% olefins and 40.0% aromatics, respectively. The optimized gasoline compositions for new engines and new vehicles have low aromatics and high olefins contents.

  16. The effect of two ammonia-emission-reducing pig housing systems on odour emission.

    PubMed

    Mol, G; Ogink, N W M

    2004-01-01

    Odour nuisance from agricultural activities is increasing in densely populated countries like the Netherlands. To develop adequate regulations, a large-scale, government-financed monitoring programme was started in the mid-1990s to establish odour emission levels for both conventional and low ammonia emission housing systems for cattle, pigs and poultry. The results indicate that high- and low-odour emission housing are difficult to distinguish because of the large variation within housing systems. Measurements on different farm locations within the same housing system show both a large variation between locations and within one location (in time). The latter, however, is significantly smaller, which suggests that farm management is an important determinant in odour emission that interferes with the effects of housing systems. The current research was aimed at determining the effect of two common ammonia-reducing pig-housing systems on odour emissions compared to conventional housing systems under similar management conditions. The respective reduction principles of these systems are reducing the emitting surface of the manure pit and cooling of manure in the manure pit (both pits beneath slatted floor). Five farms that combined conventional housing with one low-ammonia system (three reduced emitting surface and two manure cooling) were selected for a direct, pair-wise comparison of (olfactometric) odour emission measurements. The results show a highly significant effect (p < 0.01) for two of the three reduced emitting surface systems and for one of the two manure cooling system. The average odour reduction percentages of these systems are 35% (from 24.9 to 16.0 OUE/s per animal) and 23% (from 30.1 to 24.0 OUE/s per animal) respectively. Although odour emission reduction through the type of housing system is possible, management factors interact with the system and thereby determine whether the system reduces odour emission or not.

  17. Management of tropospheric ozone by reducing methane emissions.

    PubMed

    West, J Jason; Fiore, Arlene M

    2005-07-01

    Background concentrations of tropospheric ozone are increasing and are sensitive to methane emissions, yet methane mitigation is currently considered only for climate change. Methane control is shown here to be viable for ozone management. Identified global abatement measures can reduce approximately 10% of anthropogenic methane emissions at a cost-savings, decreasing surface ozone by 0.4-0.7 ppb. Methane controls produce ozone reductions that are widespread globally and are realized gradually (approximately 12 yr). In contrast, controls on nitrogen oxides (NOx) and nonmethane volatile organic compounds (NMVOCs) target high-ozone episodes in polluted regions and affect ozone rapidly but have a smaller climate benefit. A coarse estimate of the monetized global benefits of ozone reductions for agriculture, forestry, and human health (neglecting ozone mortality) justifies reducing approximately 17% of global anthropogenic methane emissions. If implemented, these controls would decrease ozone by -1 ppb and radiative forcing by approximately 0.12 W m(-2). We also find that climate-motivated methane reductions have air quality-related ancillary benefits comparable to those for CO2. Air quality planning should consider reducing methane emissions alongside NOx and NMVOCs, and because the benefits of methane controls are shared internationally, industrialized nations should consider emphasizing methane in the further development of climate change or ozone policies.

  18. Use of natural gas to reduce emissions in waste combustors

    SciTech Connect

    Abbasi, H.A.; Khinkis, M.J.; Dunnette, R.; Nakazato, Kunihiro

    1992-12-31

    The Institute of Gas Technology (IGT), together with industrial partners, is developing a technology that utilizes natural gas to reduce air pollutant emissions from municipal waste combustors (MWCs). This natural gas injection technology is termed METHANE de-NOX{sup sm}. The results of field evaluation tests carried out at a 90 tonne/day MWC in 1991 show simultaneous reductions of 60% in nitrogen oxides and 50% in carbon monoxide with natural gas injection equal to 15% of total waste heat input. Excess air requirements were also reduced by 40% thus increasing the overall waste-to-energy plant efficiency. This approach is now being combined with injection of sorbents to also reduce the emissions of hydrochloric acid, sulfur oxides, dioxins, and furans. This paper describes the overall system design, the results of field evaluations to date and the schedule for sorbent injection trials.

  19. Use of natural gas to reduce emissions in waste combustors

    SciTech Connect

    Abbasi, H.A.; Khinkis, M.J. ); Dunnette, R. ); Nakazato, Kunihiro )

    1992-01-01

    The Institute of Gas Technology (IGT), together with industrial partners, is developing a technology that utilizes natural gas to reduce air pollutant emissions from municipal waste combustors (MWCs). This natural gas injection technology is termed METHANE de-NOX[sup sm]. The results of field evaluation tests carried out at a 90 tonne/day MWC in 1991 show simultaneous reductions of 60% in nitrogen oxides and 50% in carbon monoxide with natural gas injection equal to 15% of total waste heat input. Excess air requirements were also reduced by 40% thus increasing the overall waste-to-energy plant efficiency. This approach is now being combined with injection of sorbents to also reduce the emissions of hydrochloric acid, sulfur oxides, dioxins, and furans. This paper describes the overall system design, the results of field evaluations to date and the schedule for sorbent injection trials.

  20. A higher harmonic control test in the DNW to reduce impulsive BVI noise

    NASA Technical Reports Server (NTRS)

    Splettstoesser, Wolf R.; Schultz, KLAUS-J.; Kube, Roland; Brooks, Thomas F.; Booth, Earl R., Jr.; Niesl, Georg; Streby, Olivier

    1994-01-01

    A model rotor acoustic test was performed to examine the benefit of higher control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulse noise. A 40-percent dynamically scaled, four-bladed model of a BO-105 main rotor was tested in the German-Dutch Wind Tunnel (DNW). Acoustic measurements were made in a large plane underneath the rotor employing a traversing in-flow microphone array in the anechoic environment of the open test section. Noise characteristics and noise directivity patterns as well as vibratory loads were measured and used to demonstrate the changes when different HHC schedules (different modes, amplitudes, phases) were applied. Dramatic changes of the acoustic signatures and the noise radiation directivity with HHC phase variations are found. Compared to the baseline conditions (without HHD), significant mid-frequency noise reductions of as much as 6 dB are obtained for low speed descent conditions where BVI is most intensive. For other rotor operating conditions with less intense BVI there is less or no benefit from the use of HHC. Low frequency loading noise and vibratory loads, especially at optimum noise reduction control settings, are found to increase.

  1. Enhanced Thermionic Emission and Low 1/f Noise in Exfoliated Graphene/GaN Schottky Barrier Diode.

    PubMed

    Kumar, Ashutosh; Kashid, Ranjit; Ghosh, Arindam; Kumar, Vikram; Singh, Rajendra

    2016-03-01

    Temperature-dependent electrical transport characteristics of exfoliated graphene/GaN Schottky diodes are investigated and compared with conventional Ni/GaN Schottky diodes. The ideality factor of graphene/GaN and Ni/GaN diodes are measured to be 1.33 and 1.51, respectively, which is suggestive of comparatively higher thermionic emission current in graphene/GaN diode. The barrier height values for graphene/GaN diode obtained using thermionic emission model and Richardson plots are found to be 0.60 and 0.72 eV, respectively, which are higher than predicted barrier height ∼0.40 eV as per the Schottky-Mott model. The higher barrier height is attributed to hole doping of graphene due to graphene-Au interaction which shifts the Fermi level in graphene by ∼0.3 eV. The magnitude of flicker noise of graphene/GaN Schottky diode increases up to 175 K followed by its decrease at higher temperatures. This indicates that diffusion currents and barrier inhomogeneities dominate the electronic transport at lower and higher temperatures, respectively. The exfoliated graphene/GaN diode is found to have lower level of barrier inhomogeneities than conventional Ni/GaN diode, as well as earlier reported graphene/GaN diode fabricated using chemical vapor deposited graphene. The lesser barrier inhomogeneities in graphene/GaN diode results in lower flicker noise by 2 orders of magnitude as compared to Ni/GaN diode. Enhanced thermionic emission current, lower level of inhomogeneities, and reduced flicker noise suggests that graphene-GaN Schottky diodes may have the underlying trend for replacing metal-GaN Schottky diodes.

  2. Reducing atmospheric noise in RST analysis of TIR satellite radiances for earthquakes prone areas satellite monitoring

    NASA Astrophysics Data System (ADS)

    Lisi, Mariano; Filizzola, Carolina; Genzano, Nicola; Paciello, Rossana; Pergola, Nicola; Tramutoli, Valerio

    Space-time fluctuations of the Earth's emitted Thermal Infrared (TIR) radiation observed from satellite from months to weeks before an earthquake are reported in several studies. Among the others, a Robust Satellite data analysis Technique (RST) was proposed (and applied to different satellite sensors in various geo-tectonic contexts) to discriminate anomalous signal transients possibly associated with earthquake occurrence from normal TIR signal fluctuations due to other possible causes (e.g. solar diurnal-annual cycle, meteorological conditions, changes in observational conditions, etc.). Variations in satellite view angle depending on satellite's passages (for polar satellites) and atmospheric water vapour fluctuations were recognized in the past as the main factors affecting the residual signal variability reducing the overall Signal-to-Noise (S/N) ratio and the potential of the RST-based approach in identifying seismically related thermal anomalies. In this paper we focus on both factors for the first time, applying the RST approach to geostationary satellites (which guarantees stable view angles) and using Land Surface Temperature (LST) data products (which are less affected by atmospheric water vapour variability) instead of just TIR radiances at the sensor. The first results, obtained in the case of the Abruzzo earthquake (6 April 2009, MW ∼ 6.3) by analyzing 6 years of SEVIRI (Spinning Enhanced Visible and Infrared Imager on board the geostationary Meteosat Second Generation satellite) LST products provided by EUMETSAT, seem to confirm the major sensitivity of the proposed approach in detecting perturbations of the Earth's thermal emission a few days before the main shock. The results achieved in terms of increased S/N ratio (in validation) and reduced ;false alarms; rate (in confutation) are discussed comparing results obtained by applying RST to LST products with those achieved by applying an identical RST analysis (using the same MSG-SEVIRI 2005

  3. Estimation of the noise contributions from blank, transmission and emission scans in PET

    SciTech Connect

    Holm, S.; Jensen, M.; Toft, P.

    1996-08-01

    This work determines the relative importance of noise from blank (B), transmission (T) and emission (E) scans in PET using a GE Advance scanner on a 20 cm cylinder, a brain phantom, and a torso-like ellipse (18/35 cm) with examples of human scans (brain O-15 water and F-18 FDG, heart FDG). Phantom E scans were acquired in both 2D and 3D modes as decay series with C-11 or F-18 over 3--6 decades of Noise Equivalent Counts (NEC). B and T scans were made using two pin sources ({approx} 500 MBq total) over 64-32768 sec. In humans only a limited subset was available. In homogeneous phantoms normalized variance (var) was estimated from pixel distributions in single images. In other objects, including the human studies, calculations were performed on differences of paired images. In all cases a fit was made to a simple noise model. The cylinder data show expected relations of T to B noise proving the adequacy of B scan times {le} 20 min for most purposes. For the brain phantom, a contour plot is provided for var (E,T). In a typical 3D O-15 water study with 0.5 M counts per central slice, a 10 min T-scan adds less than 10% to the total noise level. An example shows how to split a total scan time between E and T scans, in order to minimize the variance.

  4. Harvesting equipment to reduce particulate matter emissions from almond harvest.

    PubMed

    Faulkner, William B

    2013-01-01

    Almond harvest accounts for an estimated 12 Gg of PM10 emissions in California each harvest season. Emissions from three new, "low-dust" almond harvesters (Exact Harvest Systems E4000; Flory Industries 8550; Weiss-McNair 9800 California Special) and one exhaust abatement device (Joe DiAnna, Clean Air Concept) were compared to those from a conventional harvester operating in the same orchard. Emissions of TSP and PM10 trended lower for all new harvesters and were significantly lower for most harvesters (alpha < 0.10). Significant reductions in PM2.5 emissions were observed from two harvesters as well. Fractionation analysis was not conducted on nut samples collected in the second year of the project, but differences observed in the composition of material that would be delivered to the huller between the Exact E4000 and conventional harvesters were functionally insignificant. The results of these tests imply that new harvest technologies are able to reduce PM10 emissions from one of the largest sources in the San Joaquin Valley (SJV) of California without affecting product quality. As such, use of these new harvesters should be considered a conservation measure that would help the SJV Air Pollution Control District (SJVAPCD) meet the requirements of their PM10 maintenance plan. The results of this research indicate that new harvesting technologies have the potential to substantially reduce PM emissions from almond harvest operations over traditional harvester designs without negatively affecting product quality. As such, use of these new harvesters could aid the SJVAPCD in maintaining its attainment status for PM10 and should be considered as candidate conservation management practices for producers.

  5. On the use of surface porosity to reduce wake-stator interaction noise

    NASA Astrophysics Data System (ADS)

    Tinetti, Ana Fiorella

    An innovative application of existing technology is proposed for attenuating the effects of transient phenomena, such as rotor-stator and rotor-strut interactions, linked to noise and fatigue failure in turbomachinery environments. A computational study was designed to assess the potential of Passive Porosity Technology as a mechanism for alleviating interaction effects and radiated noise by reducing the fluctuating forces acting on the vane surfaces. The study involved a typical high bypass fan stator airfoil immersed in a free field and exposed to the effects of a transversely moving wake. Time histories of the primitive aerodynamic variables obtained from Computational Fluid Dynamics (CFD) calculations were input into an acoustic prediction code to estimate noise levels at a radial distance of ten chords from the stator airfoil. This procedure was performed on the solid airfoil to obtain a baseline, and on approximately fifty porous configurations in order to isolate those that would yield maximum noise reductions without compromising the aerodynamic performance of the stator. It was found during the study that, for a single stator immersed in a free flow field, communication between regions of high pressure differential---made possible by the use of passive porosity---tends to induce a time-dependent oscillatory pattern of small inflow-outflow regions near the stator leading edge (LE), which is well established before wake effects come into play. The oscillatory pattern starts at the LE, and travels downstream on both suction and pressure sides of the airfoil. The amplitude of the oscillations seemed to be proportional to the extension of the porous patch on the pressure side. Regardless of this effect, which may not have occurred if the airfoil were placed within a stator cascade, communication between regions of high pressure differential is necessary to significantly alter the noise radiation pattern of the stator airfoil. Whether those changes result in

  6. Autophagy Attenuates Noise-Induced Hearing Loss by Reducing Oxidative Stress

    PubMed Central

    Yuan, Hu; Wang, Xianren; Hill, Kayla; Chen, Jun; Lemasters, John; Yang, Shi-Ming

    2015-01-01

    Abstract Aims: Reactive oxygen species play a dual role in mediating both cell stress and defense pathways. Here, we used pharmacological manipulations and siRNA silencing to investigate the relationship between autophagy and oxidative stress under conditions of noise-induced temporary, permanent, and severe permanent auditory threshold shifts (temporary threshold shift [TTS], permanent threshold shift [PTS], and severe PTS [sPTS], respectively) in adult CBA/J mice. Results: Levels of oxidative stress markers (4-hydroxynonenal [4-HNE] and 3-nitrotyrosine [3-NT]) increased in outer hair cells (OHCs) in a noise-dose-dependent manner, whereas levels of the autophagy marker microtubule-associated protein light chain 3 B (LC3B) were sharply elevated after TTS but rose only slightly in response to PTS and were unaltered by sPTS noise. Furthermore, green fluorescent protein (GFP) intensity increased in GFP-LC3 mice after TTS-noise exposure. Treatment with rapamycin, an autophagy activator, significantly increased LC3B expression, while diminishing 4-HNE and 3-NT levels, reducing noise-induced hair cell loss, and, subsequently, noise-induced hearing loss (NIHL). In contrast, treatment with either the autophagy inhibitor 3-methyladenine (3MA) or LC3B siRNA reduced LC3B expression, increased 3-NT and 4-HNE levels, and exacerbated TTS to PTS. Innovation: This study demonstrates a relationship between oxidative stress and autophagy in OHCs and reveals that autophagy is an intrinsic cellular process that protects against NIHL by attenuating oxidative stress. Conclusions: The results suggest that the lower levels of oxidative stress incurred by TTS-noise exposure induce autophagy, which promotes OHC survival. However, excessive oxidative stress under sPTS-noise conditions overwhelms the beneficial potential of autophagy in OHCs and leads to OHC death and NIHL. Antioxid. Redox Signal. 22, 1308–1324. PMID:25694169

  7. Reduced Sensitivity to Charge Noise in Semiconductor Spin Qubits via Symmetric Operation

    NASA Astrophysics Data System (ADS)

    Reed, M. D.; Maune, B. M.; Andrews, R. W.; Borselli, M. G.; Eng, K.; Jura, M. P.; Kiselev, A. A.; Ladd, T. D.; Merkel, S. T.; Milosavljevic, I.; Pritchett, E. J.; Rakher, M. T.; Ross, R. S.; Schmitz, A. E.; Smith, A.; Wright, J. A.; Gyure, M. F.; Hunter, A. T.

    2016-03-01

    We demonstrate improved operation of exchange-coupled semiconductor quantum dots by substantially reducing the sensitivity of exchange operations to charge noise. The method involves biasing a double dot symmetrically between the charge-state anticrossings, where the derivative of the exchange energy with respect to gate voltages is minimized. Exchange remains highly tunable by adjusting the tunnel coupling. We find that this method reduces the dephasing effect of charge noise by more than a factor of 5 in comparison to operation near a charge-state anticrossing, increasing the number of observable exchange oscillations in our qubit by a similar factor. Performance also improves with exchange rate, favoring fast quantum operations.

  8. Technology limits for reducing EU transport sector CO2 emissions.

    PubMed

    Dray, Lynnette M; Schäfer, Andreas; Ben-Akiva, Moshe E

    2012-05-01

    Using a new data set describing the techno-economic characteristics of current and projected future transport technologies and a synthesis of existing transport demand models, lifecycle CO(2) emissions from 27 EU countries (EU27) were estimated in the absence and presence of new policy interventions to 2050. Future CO(2) emissions are strongly dependent on geographical scope and economic growth assumptions, and to a lesser extent on uncertainties in technology characteristics, but in the absence of new policy intervention they continue to rise from present-day values in all three scenarios examined. Consequently, EU27 emissions goals, which may require a 60% decrease in transport sector greenhouse gas emissions from year-1990 values by 2050, will be difficult to meet. This is even the case under widespread adoption of the most promising technologies for all modes, due primarily to limitations in biofuel production capacity and a lack of technologies that would drastically reduce CO(2) emissions from heavy trucks and intercontinental aviation.

  9. Fuel reformulation has benefits, but may not reduce NOx emissions

    SciTech Connect

    1997-05-19

    A new report by the International Energy Agency (IEA) details the results of a comprehensive survey of European automotive fuels. Current fuel reformulation trends lead to reduced emissions of carbon monoxide, hydrocarbons, and benzene from automobiles. Results for NO{sub x} emissions, however, are contradictory and inconclusive. Part 1 of the two-volume report focuses on raw materials and conversion. Part 2 looks at distribution and use. According to IEA, the report presents an overview of important aspects of raw materials and their conversion to automotive fuels. In addition to traditional fuels, the report includes sections on alternative fuels such as natural gas, hydrogen, ethers, and fuels derived from biological sources. The books also contain a detailed analysis of refinery and automotive emissions. Refinery emissions depend on the refinery processing scheme. Cat cracking refineries, for example, emit significantly greater quantities of sulfur than hydroskimming or thermal cracking refineries. In addition, the report includes data from tests of the effects of fuel reformulation on automobile emissions. This paper summarizes these results.

  10. Reducing greenhouse gas emissions for climate stabilization: framing regional options

    SciTech Connect

    Laura Schmitt Olabisi; Peter B. Reich; Kris A. Johnson; Anne R. Kapuscinski; Sangwon Suh; Elizabeth J. Wilson

    2009-03-15

    The Intergovernmental Panel on Climate Change (IPCC) has stated that stabilizing atmospheric CO{sub 2} concentrations will require reduction of global greenhouse gas (GHG) emissions by as much as 80% by 2050. Subnational efforts to cut emissions will inform policy development nationally and globally. We projected GHG mitigation strategies for Minnesota, which has adopted a strategic goal of 80% emissions reduction by 2050. A portfolio of conservation strategies, including electricity conservation, increased vehicle fleet fuel efficiency, and reduced vehicle miles traveled, is likely the most cost-effective option for Minnesota and could reduce emissions by 18% below 2005 levels. An 80% GHG reduction would require complete decarbonization of the electricity and transportation sectors, combined with carbon capture and sequestration at power plants, or deep cuts in other relatively more intransigent GHG-emitting sectors. In order to achieve ambitious GHG reduction goals, policymakers should promote aggressive conservation efforts, which would probably have negative net costs, while phasing in alternative fuels to replace coal and motor gasoline over the long-term. 31 refs., 3 figs., 1 tab.

  11. Can reducing black carbon emissions counteract global warming?

    PubMed

    Bond, Tami C; Sun, Haolin

    2005-08-15

    Field measurements and model results have recently shown that aerosols may have important climatic impacts. One line of inquiry has investigated whether reducing climate-warming soot or black carbon aerosol emissions can form a viable component of mitigating global warming. We review and acknowledge scientific arguments against considering aerosols and greenhouse gases in a common framework, including the differences in the physical mechanisms of climate change and relevant time scales. We argue that such a joint consideration is consistent with the language of the United Nations Framework Convention on Climate Change. We synthesize results from published climate-modeling studies to obtain a global warming potential for black carbon relative to that of CO2 (680 on a 100 year basis). This calculation enables a discussion of cost-effectiveness for mitigating the largest sources of black carbon. We find that many emission reductions are either expensive or difficult to enact when compared with greenhouse gases, particularly in Annex I countries. Finally, we propose a role for black carbon in climate mitigation strategies that is consistent with the apparently conflicting arguments raised during our discussion. Addressing these emissions is a promising way to reduce climatic interference primarily for nations that have not yet agreed to address greenhouse gas emissions and provides the potential for a parallel climate agreement.

  12. Reducing greenhouse gas emissions for climate stabilization: framing regional options.

    PubMed

    Olabisi, Laura Schmitt; Reich, Peter B; Johnson, Kris A; Kapuscinski, Anne R; Su, Sangwon H; Wilson, Elizabeth J

    2009-03-15

    The Intergovernmental Panel on Climate Change (IPCC) has stated that stabilizing atmospheric CO2 concentrations will require reduction of global greenhouse gas (GHG) emissions by as much as 80% by 2050. Subnational efforts to cut emissions will inform policy development nationally and globally. We projected GHG mitigation strategies for Minnesota, which has adopted a strategic goal of 80% emissions reduction by 2050. A portfolio of conservation strategies, including electricity conservation, increased vehicle fleet fuel efficiency, and reduced vehicle miles traveled, is likely the most cost-effective option for Minnesota and could reduce emissions by 18% below 2005 levels. An 80% GHG reduction would require complete decarbonization of the electricity and transportation sectors, combined with carbon capture and sequestration at power plants, or deep cuts in other relatively more intransigent GHG-emitting sectors. In order to achieve ambitious GHG reduction goals, policymakers should promote aggressive conservation efforts, which would probably have negative net costs, while phasing in alternative fuels to replace coal and motor gasoline over the long-term.

  13. Can reducing black carbon emissions counteract global warming?

    SciTech Connect

    Tami C. Bond; Haolin Sun

    2005-08-15

    Field measurements and model results have recently shown that aerosols may have important climatic impacts. One line of inquiry has investigated whether reducing climate-warming soot or black carbon aerosol emissions can form a viable component of mitigating global warming. Black carbon is produced by poor combustion, from our example hard coal cooking fires for and industrial pulverized coal boilers. The authors review and acknowledge scientific arguments against considering aerosols and greenhouse gases in a common framework, including the differences in the physical mechanisms of climate change and relevant time scales. It is argued that such a joint consideration is consistent with the language of the United Nations Framework Convention on Climate Change. Results from published climate-modeling studies are synthesized to obtain a global warming potential for black carbon relative to that of CO{sub 2} (680 on a 100 year basis). This calculation enables a discussion of cost-effectiveness for mitigating the largest sources of black carbon. It is found that many emission reductions are either expensive or difficult to enact when compared with greenhouse gases, particularly in Annex I countries. Finally, a role for black carbon in climate mitigation strategies is proposed that is consistent with the apparently conflicting arguments raised during the discussion. Addressing these emissions is a promising way to reduce climatic interference primarily for nations that have not yet agreed to address greenhouse gas emissions and provides the potential for a parallel climate agreement. 31 refs., 3 figs., 1 tab.

  14. A Computationally Efficient Filter for Reducing Shot Noise in Low S/N Data

    PubMed Central

    Okada, Mami; Ishikawa, Tomoe; Ikegaya, Yuji

    2016-01-01

    Functional multineuron calcium imaging (fMCI) provides a useful experimental platform to simultaneously capture the spatiotemporal patterns of neuronal activity from a large cell population in situ. However, fMCI often suffers from low signal-to-noise ratios (S/N). The main factor that causes the low S/N is shot noise that arises from photon detectors. Here, we propose a new denoising procedure, termed the Okada filter, which is designed to reduce shot noise under low S/N conditions, such as fMCI. The core idea of the Okada filter is to replace the fluorescence intensity value of a given frame time with the average of two values at the preceding and following frames unless the focused value is the median among these three values. This process is iterated serially throughout a time-series vector. In fMCI data of hippocampal neurons, the Okada filter rapidly reduces background noise and significantly improves the S/N. The Okada filter is also applicable for reducing shot noise in electrophysiological data and photographs. Finally, the Okada filter can be described using a single continuous differentiable equation based on the logistic function and is thus mathematically tractable. PMID:27304217

  15. Compact, Lightweight, Ceramic Matrix Composite (CMC) Based Acoustic Liners for Reducing Subsonic Jet Aircraft Engine Noise

    NASA Technical Reports Server (NTRS)

    Kiser, J. Douglas; Grady, Joseph E.; Miller, Christopher J.; Hultgren, Lennart S.; Jones, Michael G.

    2016-01-01

    Recent developments have reduced fan and jet noise contributions to overall subsonic aircraft jet-engine noise. Now, aircraft designers are turning their attention toward reducing engine core noise. The NASA Glenn Research Center and NASA Langley Research Center have teamed to investigate the development of a compact, lightweight acoustic liner based on oxide/oxide ceramic matrix composite (CMC) materials. The NASA team has built upon an existing oxide/oxide CMC sandwich structure concept that provides monotonal noise reduction. Oxide/oxide composites have good high temperature strength and oxidation resistance, which could allow them to perform as core liners at temperatures up to 1000C (1832F), and even higher depending on the selection of the composite constituents. NASA has initiated the evaluation of CMC-based liners that use cells of different lengths (variable-depth channels) or effective lengths to achieve broadband noise reduction. Reducing the overall liner thickness is also a major goal, to minimize the volume occupied by the liner. As a first step toward demonstrating the feasibility of our concepts, an oxide/oxide CMC acoustic testing article with different channel lengths was tested. Our approach, summary of test results, current status, and goals for the future are reported.

  16. Method of reducing chlorofluorocarbon refrigerant emissions in the atmosphere

    SciTech Connect

    DeVault, R.C.; Fairchild, P.D.; Biermann, W.J.

    1990-06-19

    This patent describes a method of reducing escape of refrigerant emissions to the atmosphere during removal of a chlorofluorocarbon refrigerant from a vapor compression cooling system or heat pump. The method comprises contacting the chlorofluorocarbon refrigerant during removal with a sorbent material into which the chlorofluorocarbon refrigerant can be dissolved, the sorbent material being selected from the group consisting of N-methyl-2-pyrrolidone, ethyl tetrahydro furfuryl ether, tetramethylene glycol dimethylether, triethylene glycol dimethylether, N,N-dimethyl formamide, dimethylamides, and tetrachloroethane.

  17. An experimental investigation of reducing advanced turboprop cabin noise by wing shielding

    NASA Technical Reports Server (NTRS)

    Dittmar, J. H.

    1986-01-01

    An experimental investigation was undertaken to determine if wing shielding could reduce the noise impacting the fuselage of an advanced turboprop airplane. Four wings were tested behind two eight-bladed propeller models. Significant shielding of the propeller noise was observed and a particular wing-propeller geometry was identified to provide the most shielding. Specifically, an up-inboard rotation would be needed for a low-wing airplane and a down-inboard rotation for a high-wing airplane. As the axial Mach number was increased, the position where the shielding starts moved farther downstream. This shift in the start of shielding was roughly a straight line with respect to Mach number between M = 0.7 and M = 0.8. At M = 0.85 the start of shielding does not shift any farther downstream. A simple barrier noise-reduction model gave the same trends with transducer positions as did the data, and, if corrected for Mach number shift, the model might be used to provide estimates of the wing shielding. Besides providing a barrier to the noise reaching the shielded area, the wing also reflects some of the noise back onto the unshielded area. This can make the noise difference between the unshielded and shielded areas of the fuselage larger than would be expected by simple wind shielding.

  18. A Novel Approach for Reducing Rotor Tip-Clearance Induced Noise in Turbofan Engines

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R.; Li, Fei; Choudhari, Meelan

    2001-01-01

    Rotor tip-clearance induced noise, both in the form of rotor self noise and rotor-stator interaction noise , constitutes a significant component of total fan noise. Innovative yet cost effective techniques to suppress rotor-generated noise are, therefore, of foremost importance for improving the noise signature of turbofan engines. To that end, the feasibility of a passive porous treatment strategy to positively modify the tip-clearance flow field is addressed. The present study is focused on accurate viscous flow calculations of the baseline and the treated rotor flow fields. Detailed comparison between the computed baseline solution and experimental measurements shows excellent agreement. Tip-vortex structure, trajectory, strength, and other relevant aerodynamic quantities are extracted from the computed database. Extensive comparison between the untreated and treated tip-clearance flow fields is performed. The effectiveness of the porous treatment for altering the rotor-tip vortex flow field in general and reducing the intensity of the tip vortex, in particular, is demonstrated. In addition, the simulated flow field for the treated tip clearly shows that substantial reduction in the intensity of both the shear layer roll-up and boundary layer separation on the wall is achieved.

  19. Method for reducing CO2, CO, NOX, and SOx emissions

    DOEpatents

    Lee, James Weifu; Li, Rongfu

    2002-01-01

    Industrial combustion facilities are integrated with greenhouse gas-solidifying fertilizer production reactions so that CO.sub.2, CO, NO.sub.x, and SO.sub.x emissions can be converted prior to emission into carbonate-containing fertilizers, mainly NH.sub.4 HCO.sub.3 and/or (NH.sub.2).sub.2 CO, plus a small fraction of NH.sub.4 NO.sub.3 and (NH.sub.4).sub.2 SO.sub.4. The invention enhances sequestration of CO.sub.2 into soil and the earth subsurface, reduces N0.sub.3.sup.- contamination of surface and groundwater, and stimulates photosynthetic fixation of CO.sub.2 from the atmosphere. The method for converting CO.sub.2, CO, NO.sub.x, and SO.sub.x emissions into fertilizers includes the step of collecting these materials from the emissions of industrial combustion facilities such as fossil fuel-powered energy sources and transporting the emissions to a reactor. In the reactor, the CO.sub.2, CO, N.sub.2, SO.sub.x, and/or NO.sub.x are converted into carbonate-containing fertilizers using H.sub.2, CH.sub.4, or NH.sub.3. The carbonate-containing fertilizers are then applied to soil and green plants to (1) sequester inorganic carbon into soil and subsoil earth layers by enhanced carbonation of groundwater and the earth minerals, (2) reduce the environmental problem of NO.sub.3.sup.- runoff by substituting for ammonium nitrate fertilizer, and (3) stimulate photosynthetic fixation of CO.sub.2 from the atmosphere by the fertilization effect of the carbonate-containing fertilizers.

  20. Mining noise affects loud call structures and emission patterns of wild black-fronted titi monkeys.

    PubMed

    Duarte, M H L; Kaizer, M C; Young, R J; Rodrigues, M; Sousa-Lima, R S

    2017-09-11

    Anthropogenic noise pollution is increasing and can constrain acoustic communication in animals. Our aim was to investigate if the acoustic parameters of loud calls and their diurnal pattern in the black-fronted titi monkey (Callicebus nigrifrons) are affected by noise produced by mining activity in a fragment of Atlantic Forest in Brazil. We installed two passive acoustic monitoring devices to record sound 24 h/day, 7 days every 2 months, for a year; one unit was close to an opencast mine and the other 2.5 km away from it. Both sites presented similar habitat structures and were inhabited by groups of black-fronted titi monkeys. We quantified the noise at both sites by measuring the equivalent continuous sound level every 2 months for 1 year and quantified the emission of loud calls by titi monkeys through visual inspection of the recordings. The close site presented higher ambient noise levels than the far site. The quantitative comparison of loud calls of black-fronted titi monkeys between the two sites showed less calling activity in the site close to the mine than in the site further away. Approximately 20 % of the calls detected at the site close to the mine were masked by noise from truck traffic. Loud calls were longer at the site far from the mine and the diurnal patterns of vocal activity differed in the amount of calling as well as in the timing of peak calling activity between the two sites. Our results indicate that mining noise may constrain titi monkeys' long-distance vocal communication. Loud calls occupy a similar frequency band to mining noise, and an increase in ambient noise may be triggering black-fronted titi monkeys to adjust their long-distance communication patterns to avoid masking of their calls. Given that vocalizations are an important means of social interaction in this species, there are concerns about the impact of mining noise on populations exposed to this human activity.

  1. Feeding reduced crude protein diets with crystalline amino acids supplementation reduce air gas emissions from housing.

    PubMed

    Li, Q-F; Trottier, N; Powers, W

    2015-02-01

    The objective of this study was to test the hypothesis that reducing dietary CP by 1.5% and supplementing crystalline AA (CAA) to meet the standardized ileal digestible (SID) AA requirements for growing and finishing pigs decreases air emissions of ammonia (NH), nitrous oxide (NO), and carbon dioxide (CO) compared with an industry standard diet, without reducing growth performance. Seventy-two pigs were allocated to 12 rooms (6 pigs per room) and 2 diets (6 rooms per diet) formulated according to a 5-phase feeding program across the grow-finish period (107 d total). The diets consisted of a standard diet containing 18.5 to 12.2% CP or a reduced CP diet containing 17.5 to 11.0% CP + CAA over the course of the 5-phase feeding program. Gases (NH, NO, hydrogen sulfide, methane, nonmethane total hydrocarbon, and CO) and ventilation rates were measured continuously from the rooms. Compared with standard diet, ADG and feed conversion of pigs fed reduced CP + CAA diets did not differ (2.7 kg gain/d and 0.37 kg gain/kg feed, respectively). Compared with standard diet, feeding reduced CP + CAA diets decreased ( < 0.01) NH emissions by 46% over the 107-d period (5.4 and 2.9 g · pig · d, respectively). Change in NH emissions for each percentage unit reduction in dietary CP concentration corresponded with 47.9, 53.2, 26.8, 26.5, and 51.6% during Phases 1 through 5, respectively. Emissions of other gases did not differ between diets. Feeding reduced CP diets formulated based on SID AA requirements for grow-finisher swine is effective in reducing NH emissions from housing compared with recent industry formulations and does not impact growth performances.

  2. Detecting incipient inner-ear damage from impulse noise with otoacoustic emissions.

    PubMed

    Marshall, Lynne; Lapsley Miller, Judi A; Heller, Laurie M; Wolgemuth, Keith S; Hughes, Linda M; Smith, Shelley D; Kopke, Richard D

    2009-02-01

    Audiometric thresholds and otoacoustic emissions (OAEs) were measured in 285 U.S. Marine Corps recruits before and three weeks after exposure to impulse-noise sources from weapons' fire and simulated artillery, and in 32 non-noise-exposed controls. At pre-test, audiometric thresholds for all ears were noise-exposed volunteers with complete data sets for both ears showed significant decreases in OAE amplitude but no change in audiometric thresholds. STSs and significant emission shifts (SESs) between 2 and 4 kHz in individual ears were identified using criteria based on the standard error of measurement from the control group. There was essentially no association between the occurrence of STS and SES. There were more SESs than STSs, and the group of SES ears had more STS ears than the group of no-SES ears. The increased sensitivity of OAEs in comparison to audiometric thresholds was shown in all analyses, and low-level OAEs indicate an increased risk of future hearing loss by as much as ninefold.

  3. A noise study of the A-6 airplane and techniques for reducing its aural detection distance

    NASA Technical Reports Server (NTRS)

    Hilton, D. A.; Connor, A. B.; Hubbard, H. H.

    1975-01-01

    A study was undertaken to determine the noise reduction potential of the A-6 airplane in order to reduce its aural detection distance. Static and flyby noise measurements were taken to document the basic airplane signature. The low-frequency noise which is generally most critical for aural detection was found to be broad-band in nature from this airplane, and its source is the turbojet engine exhaust. High-frequency compressor noise, which is characteristic of turbojet powerplants, and which is prominent at close range for this airplane, has no measurable effect on aural detection distance. The use of fluted-engine exhaust nozzles to change the far-field noise spectra is suggested as a possible means for reducing the aural detection distances. Detection distances associated with eight-lobe and four-lobe nozzles are estimated for a 1,000-foot altitude and grassy terrain to decrease from 4 miles to about 3 miles, and from 3 miles to about 2 miles for a 300-foot altitude and grassy terrain.

  4. Reducing media noise of perpendicular magnetic recording tape for over-50 TB class data cartridge

    NASA Astrophysics Data System (ADS)

    Matsunuma, S.; Inoue, T.; Watanabe, T.; Doi, T.; Gomi, S.; Mashiko, Y.; Hirata, K.; Nakagawa, S.

    2011-04-01

    To reduce medium noise inherent in a perpendicular magnetic recording tape, which is deposited by facing targets sputtering, we have examined an epitaxial double-layered structure consisting of a soft magnetic underlayer (SUL), bcc-FeCoB/fcc-NiFe/Si/bcc-FeCoB, on a 4.5 μm para-aromatic polyamide (aramid) film. An epitaxial soft magnetic bilayer reduces broadband noise by 5.6 dB at 337 kilo fluxchanges per inch (kfci) compared to a single SUL medium (Tape S). This is due to the reduction in the low-frequency noise, which originates from the domain walls of the SUL. Improvement of the crystal orientation of the magnetic layer hcp-CoPtCr-SiO2 and the intermediate layer hcp-Ru by inserting a fcc-NiFe spacer in laminated SULs extends the roll-off curve toward high linear density. When each SUL layer of the bilayer was made thinner, from 25 nm (Tape D2) to 10 nm (Tape D1), the medium noise decreased, improving the signal-to-noise ratio by 8.6 dB at 337 kfci compared to Tape S. In a high resolution playback test of Tape D1, an areal density of 45.0 gigabits per square inch (Gb/in.2) was confirmed. Achieved areal density means the capability of an over-50 terabyte (TB) capacity for a typical linear-formatted data cartridge.

  5. A research program to reduce the interior noise in general aviation aircraft, index and summary

    NASA Technical Reports Server (NTRS)

    Morgan, L.; Jackson, K.; Roskam, J.

    1985-01-01

    This report is an index of the published works from NASA Grant NSG 1301, entitled A Research Program to Reduce the Interior Noise in General Aviation Aircraft. Included are a list of all published reports and papers, a compilation of test specimen characteristics, and summaries of each published work.

  6. Exercise based transportation reduces oil consumption and carbon emissions

    NASA Astrophysics Data System (ADS)

    Higgins, P. A.

    2004-12-01

    Current abuse and misrepresentation of science hinders society's ability to address climate change. Scientific abuse results, in part, from a widespread perception that curbing emissions will require substantial economic, political, or personal sacrifice. Here I provide one example to illustrate that this perception is false. Simply walking or biking the amount recommended for a healthy lifestyle could reduce carbon emissions up to 11 percent if the distances traveled were substituted for car travel. This level of exercise is also sufficient to eliminate obese and overweight conditions in a few years without draconian diet plans. A reduction in carbon dioxide emissions of roughly 35 percent is possible if the revenue saved through decreased health care spending on obesity is redirected toward carbon abatement. This emissions reduction far exceeds that required by the Kyoto Protocol at no net cost. Finally, widespread substitution of driving with distances traveled during recommended daily exercise would considerably ease societal dependence on oil, which leads not only to climate change but also to air pollution, political and economic instability and habitat degradation. Thus, exercise based transportation constitutes a potentially favorable alternative to the energy and diet plans that are currently under consideration and a substantial step toward dealing with the threat of climate change.

  7. Global cost estimates of reducing carbon emissions through avoided deforestation.

    PubMed

    Kindermann, Georg; Obersteiner, Michael; Sohngen, Brent; Sathaye, Jayant; Andrasko, Kenneth; Rametsteiner, Ewald; Schlamadinger, Bernhard; Wunder, Sven; Beach, Robert

    2008-07-29

    Tropical deforestation is estimated to cause about one-quarter of anthropogenic carbon emissions, loss of biodiversity, and other environmental services. United Nations Framework Convention for Climate Change talks are now considering mechanisms for avoiding deforestation (AD), but the economic potential of AD has yet to be addressed. We use three economic models of global land use and management to analyze the potential contribution of AD activities to reduced greenhouse gas emissions. AD activities are found to be a competitive, low-cost abatement option. A program providing a 10% reduction in deforestation from 2005 to 2030 could provide 0.3-0.6 Gt (1 Gt = 1 x 10(5) g) CO(2).yr(-1) in emission reductions and would require $0.4 billion to $1.7 billion.yr(-1) for 30 years. A 50% reduction in deforestation from 2005 to 2030 could provide 1.5-2.7 Gt CO(2).yr(-1) in emission reductions and would require $17.2 billion to $28.0 billion.yr(-1). Finally, some caveats to the analysis that could increase costs of AD programs are described.

  8. Effect of trailing edge serration-flow misalignment on airfoil noise emissions

    NASA Astrophysics Data System (ADS)

    Arce León, Carlos; Merino-Martínez, Roberto; Ragni, Daniele; Avallone, Francesco; Scarano, Fulvio; Pröbsting, Stefan; Snellen, Mirjam; Simons, Dick G.; Madsen, Jesper

    2017-09-01

    The broadband noise generated by the scattering of turbulent flow at the trailing edge of a NACA 0018 airfoil with trailing edge serrations is investigated, varying both the airfoil angle of attack and serration flap angle. Acoustic emissions from the trailing edge are measured using a microphone array. The noise level is observed to be higher than that of the airfoil without serrations at frequencies beyond a crossover value. The latter is found to scale with a characteristic Strouhal number based upon the boundary layer thickness and the freestream velocity. A satisfactory collapse of the results under varying angles of attack and freestream velocities is observed. The modifications of the hydrodynamic behavior and the noise increase are linked by high-speed observations conducted with particle image velocimetry. An increase in the energy of turbulent fluctuations is also observed at the expected crossover frequency. The dominant cause of the increased noise is thereby identified at the pressure side edge of the serrations at a given flap angle.

  9. Noise estimation technique to reduce the effects of 1/f noise in Open Path Tunable Diode Laser Absorption Spectrometry (OP-TDLAS)

    NASA Astrophysics Data System (ADS)

    Mohammad, Israa L.; Anderson, Gary T.; Chen, Youhua

    2014-06-01

    Many techniques using high frequency modulation have been proposed to reduce the effects of 1/f noise in tunable diode-laser absorption spectroscopy (TDLAS). The instruments and devices used by these techniques are not suitable for space applications that require small, low mass and low power instrumentation. A new noise estimation technique has already been proposed and validated for two lasers to reduce the effect of 1/f noise at lower frequencies. This paper extends the noise estimation technique and applies it using one distribution feedback (DFB) laser diode. In this method a DFB laser diode is excited at two slightly different frequencies, giving two different harmonics that can be used to estimate the total noise in the measurement. Simulations and experimental results on ammonia gas validate that the 1/f noise is effectively reduced by the noise estimation technique using one laser. Outdoor experimental results indicate that the effect of 1/f noise is reduced to more than 1/4 its normal value.

  10. Impulsive microwave burst and solar noise storm emission resolved with the VLA

    NASA Technical Reports Server (NTRS)

    Willson, Robert F.; Lang, Kenneth R.; Liggett, Margaret

    1990-01-01

    The evolution of a microwave burst at 20.7 cm wavelength and a type I noise storm at 91.6 cm wavelength are examined using VLA. The magnetic loops in the two spectral regions are studied. The sizes and brightness temperatures of the 20.7 cm burst sources are compared with those predicted by multithermal and nonthermal models of microwave burst emission of Dulk and Dennis (1982). The data reveal that: (1) the precursor, impulsive, and post-impulsive phases of the 20.7 cm burst are located in spatially separated sources; (2) the gradual enhancement of a 91.6 cm noise storm continuum source suggests a feed-back mechanism exists between activity in higher and lower lying loops; and (3) the derived magnetic field strengths at 20.7 cm for the nonthermal models are 35-160 G with core field strengths of 125-220 G.

  11. Experimental investigation of the noise emission of axial fans under distorted inflow conditions

    NASA Astrophysics Data System (ADS)

    Zenger, Florian J.; Renz, Andreas; Becher, Marcus; Becker, Stefan

    2016-11-01

    An experimental investigation on the noise emission of axial fans under distorted inflow conditions was conducted. Three fans with forward-skewed fan blades and three fans with backward-skewed fan blades and a common operating point were designed with a 2D element blade method. Two approaches were adopted to modify the inflow conditions: first, the inflow turbulence intensity was increased by two different rectangular grids and second, the inflow velocity profile was changed to an asymmetric characteristic by two grids with a distinct bar stacking. An increase in the inflow turbulence intensity affects both tonal and broadband noise, whereas a non-uniform velocity profile at the inlet influences mainly tonal components. The magnitude of this effect is not the same for all fans but is dependent on the blade skew. The impact is greater for the forward-skewed fans than for the backward-skewed and thus directly linked to the fan blade geometry.

  12. Investigation of a design modification for double helical gears reducing vibration and noise

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Fang, Zong-De; Jia, Hai-Tao

    2010-03-01

    To reduce vibration and noise and increase transmission efficiency, a three segment method for modifying the pinion profile was proposed. Cutter surface equations were deduced by changing the shape of the cutter-edge, substituting three segment parabolas for the line. The influence of longitudinal tooth modifications on tooth surface load distributions was discussed. Transmission error minimization and uniformity of tooth surface load distribution were chosen as optimization goals and the modified parameters were obtained by applying the complex method. Finally, an experiment comparing the loaded transmission error, vibration, and noise both before and after modifications was carried out. The results indicate that the modified design is reliable.

  13. Potential options to reduce GHG emissions in Venezuela

    SciTech Connect

    Pereira, N.; Bonduki, Y.; Perdomo, M.

    1996-12-31

    The Government of Venezuela ratified the United Nations Framework Convention on Climate Change (UNFCCC) in December, 1994. The Convention requires all parties to develop and publish national inventories of anthropogenic greenhouse gas emissions (GHG) as well as national plans to reduce or control emissions, taking into account their common but differentiated responsibilities and their specific national and regional development priorities, objectives, and circumstances. Within this context, the Ministry of Environment and Renewable Natural Resources and the Ministry of Energy and Mines developed the `Venezuelan Case-Study to Address Climate Change`. The study was initiated in October 1993, with the financial and technical assistance of the Government of United States, through the U.S. Country Studies Program (USCSP), and the Global Environment Facility (GEF), through the United Nations Environment Programme (UNEP).

  14. Reducing greenhouse gas emissions in agriculture without compromising food security?

    NASA Astrophysics Data System (ADS)

    Frank, Stefan; Havlík, Petr; Soussana, Jean-Francois; Levesque, Antoine; Valin, Hugo; Wollenberg, Eva; Kleinwechter, Ulrich; Fricko, Oliver; Gusti, Mykola; Herrero, Mario; Smith, Pete; Hasegawa, Tomoko; Kraxner, Florian; Obersteiner, Michael

    2017-04-01

    To keep global warming possibly below 1.5 C and mitigate adverse effects of climate change, agriculture, like all other sectors, will have to contribute to efforts in achieving net negative emissions by the end of the century. Cost-efficient distribution of mitigation across regions and sectors is typically calculated using a global uniform carbon price in climate stabilization scenarios. However, in reality such a carbon price could substantially affect other Sustainable Development Goals. Here, we assess the implications of climate change mitigation in agriculture for agricultural production and food security using an integrated modelling framework and explore ways of relaxing the competition between climate change mitigation and food availability. Using a scenario that limits global warming to 1.5 C, results indicate a food calorie loss in 2050 of up to 330 kcal per capita in food insecure countries. If only developed countries participated in the mitigation effort, the calorie loss would be 40 kcal per capita, however the climate target would not be achieved. Land-rich countries with a high proportion of emissions from land use change, such as Brazil, could reduce emissions with only a marginal effect on food availability. In contrast, agricultural mitigation in high population (density) countries, such as China and India, would lead to substantial food calorie loss without a major contribution to global GHG mitigation. Increasing soil carbon sequestration on agricultural land using a comprehensive set of management options, would allow achieving a 1.5 C target while reducing the implied calorie loss by up to 70% and storing up to 3.5 GtCO2 in soils. Hence, the promotion of so called "win-win" mitigation options i.e. soil carbon sequestration, and ensuring successful mitigation of land use change emissions are crucial to stabilize the climate without deteriorating food security.

  15. Methods for designing treatments to reduce interior noise of predominant sources and paths in a single engine light aircraft

    NASA Technical Reports Server (NTRS)

    Hayden, Richard E.; Remington, Paul J.; Theobald, Mark A.; Wilby, John F.

    1985-01-01

    The sources and paths by which noise enters the cabin of a small single engine aircraft were determined through a combination of flight and laboratory tests. The primary sources of noise were found to be airborne noise from the propeller and engine casing, airborne noise from the engine exhaust, structureborne noise from the engine/propeller combination and noise associated with air flow over the fuselage. For the propeller, the primary airborne paths were through the firewall, windshield and roof. For the engine, the most important airborne path was through the firewall. Exhaust noise was found to enter the cabin primarily through the panels in the vicinity of the exhaust outlet although exhaust noise entering the cabin through the firewall is a distinct possibility. A number of noise control techniques were tried, including firewall stiffening to reduce engine and propeller airborne noise, to stage isolators and engine mounting spider stiffening to reduce structure-borne noise, and wheel well covers to reduce air flow noise.

  16. Methods for designing treatments to reduce interior noise of predominant sources and paths in a single engine light aircraft

    NASA Astrophysics Data System (ADS)

    Hayden, Richard E.; Remington, Paul J.; Theobald, Mark A.; Wilby, John F.

    1985-03-01

    The sources and paths by which noise enters the cabin of a small single engine aircraft were determined through a combination of flight and laboratory tests. The primary sources of noise were found to be airborne noise from the propeller and engine casing, airborne noise from the engine exhaust, structureborne noise from the engine/propeller combination and noise associated with air flow over the fuselage. For the propeller, the primary airborne paths were through the firewall, windshield and roof. For the engine, the most important airborne path was through the firewall. Exhaust noise was found to enter the cabin primarily through the panels in the vicinity of the exhaust outlet although exhaust noise entering the cabin through the firewall is a distinct possibility. A number of noise control techniques were tried, including firewall stiffening to reduce engine and propeller airborne noise, to stage isolators and engine mounting spider stiffening to reduce structure-borne noise, and wheel well covers to reduce air flow noise.

  17. Reducing the Read Noise of the James Webb Space Telescope Near Infrared Spectrograph Detector Subsystem

    NASA Technical Reports Server (NTRS)

    Rauscher, Bernard; Arendt, Richard G.; Fixsen, D. J.; Lindler, Don; Loose, Markus; Moseley, S. H.; Wilson, D. V.

    2012-01-01

    We describe a Wiener optimal approach to using the reference output and reference pixels that are built into Teledyne's HAWAII-2RG detector arrays. In this way, we are reducing the total noise per approximately 1000 second 88 frame up-the-ramp dark integration from about 6.5 e- rms to roughly 5 e- rms. Using a principal components analysis formalism, we achieved these noise improvements without altering the hardware in any way. In addition to being lower, the noise is also cleaner with much less visible correlation. For example, the faint horizontal banding that is often seen in HAWAII-2RG images is almost completely removed. Preliminary testing suggests that the relative gains are even higher when using non flight grade components. We believe that these techniques are applicable to most HAWAII-2RG based instruments.

  18. Reduced sampling efficiency causes degraded Vernier hyperacuity with normal aging: Vernier acuity in position noise.

    PubMed

    Li, Roger W; Brown, Brian; Edwards, Marion H; Ngo, Charlie V; Chat, Sandy W; Levi, Dennis M

    2012-01-01

    Vernier acuity, a form of visual hyperacuity, is amongst the most precise forms of spatial vision. Under optimal conditions Vernier thresholds are much finer than the inter-photoreceptor distance. Achievement of such high precision is based substantially on cortical computations, most likely in the primary visual cortex. Using stimuli with added positional noise, we show that Vernier processing is reduced with advancing age across a wide range of noise levels. Using an ideal observer model, we are able to characterize the mechanisms underlying age-related loss, and show that the reduction in Vernier acuity can be mainly attributed to the reduction in efficiency of sampling, with no significant change in the level of internal position noise, or spatial distortion, in the visual system.

  19. Reducing the noise floor in optoelectronic oscillator by optimizing the operation of modulator

    NASA Astrophysics Data System (ADS)

    Tong, Guochuan; Jin, Tao; Chi, Hao; Zheng, Junchao; Zhu, Xiang; Lai, Tianhao; Wu, Xidong; Shi, Zhiguo

    2016-10-01

    An intensity modulator is a key component in an optoelectronic oscillator (OEO). It is necessary to investigate the effects of some of the operating parameters of the modulator on OEO phase noise. Since the OEO optimized oscillation power is related to the nonlinear effect of the modulator, an extended analysis is made by considering both the saturation effects of the modulator and the radio frequency amplifier. Experimental results show that a 5-dB improvement of phase noise performance is achieved. In addition, a theoretical and experimental study on the DC bias-drifting problem of the modulator and its induced phase noise fluctuations is proposed. It is found that the saturated operation of the amplifier is helpful in reducing the fluctuation range. The presented results can be used to guide the design of high-quality OEOs.

  20. Magnetic Barkhausen noise and magneto acoustic emission in pressure vessel steel

    NASA Astrophysics Data System (ADS)

    Neyra Astudillo, Miriam Rocío; López Pumarega, María Isabel; Núñez, Nicolás Marcelo; Pochettino, Alberto; Ruzzante, José

    2017-03-01

    Magnetic Barkhausen Noise (MBN) and Magneto Acoustic Emission (MAE) were studied in A508 Class II forged steel used for pressure vessels in nuclear power stations. The magnetic experimental determinations were completed with a macro graphic study of sulfides and the texture analysis of the material. The analysis of these results allows us to determine connections between the magnetic anisotropy, texture and microstructure of the material. Results clearly suggest that the plastic flow direction is different from the forging direction indicated by the material supplier

  1. New combustion technology reduces pollutant emissions and operating costs

    SciTech Connect

    Not Available

    1988-11-01

    The new system, called PEP-99, is used to produce an emulsified fuel. This new fuel is being used in an 850 megawatt boiler used to generate electric power by the Niagara Mohawk Power Corporation in Oswego, NY, where it has reduced pollutant levels and maintained the boiler peak thermal efficiency for longer periods of time as compared to performance with conventional No. 6 fuel oil. Hydroflow's PEP-99 products are designed for the on-site production of water-in-oil fuel emulsions. Very small droplets of water are mixed uniformly throughout the fuel oil and are contained within larger droplets of oil. When the fuel is sprayed into the hot combustion chamber, the water is flashed to steam, creating an explosive force that shatters each individual oil droplet. These smaller particles of oil burn much more cleanly and completely than standard residual fuels. This reduces particulate emissions or unburned carbon which is discharged to the atmosphere. The presence of water in the fuel emulsion slightly reduces the combustion temperature resulting in a significant reduction in nitrogen oxides. PEP-99 emulsified fuels typically provide 40 to 50 percent reduction in nitrogen oxides, 30-40 percent reduction in SO/sub 3/ and up to 50 percent cut in particulate emissions.

  2. Emission of reduced malodorous sulfur gases from wastewater treatment plants

    SciTech Connect

    Devai, I.; DeLaune, R.D.

    1999-03-01

    The emission of malodorous gaseous compounds from wastewater collection and treatment facilities is a growing maintenance and environmental problem. Numerous gaseous compounds with low odor detection thresholds are emitted from these facilities. Sulfur-bearing gases represent compounds with the lowest odor detection threshold. Using solid adsorbent preconcentration and gas chromatographic methods, the quantity and composition of reduced malodorous sulfur gases emitted from various steps of the treatment process were determined in wastewater treatment plants in Baton Rouge, Louisiana. Hydrogen sulfide, which is a malodorous, corrosive, and potentially toxic gas, was the most dominant volatile reduced sulfur (S) compound measured. Concentrations were not only more than the odor detection threshold of hydrogen sulfide, but above levels that may affect health during long-term exposure. The concentrations of methanethiol, dimethyl sulfide, carbon disulfide, and carbonyl sulfide were significantly less than hydrogen sulfide. However, even though emissions of reduced sulfur gases other than hydrogen sulfide were low, previous studies suggested that long-term exposure to such levels may cause respiratory problems and other symptoms.

  3. Observation of reduced 1/f noise in graphene field effect transistors on boron nitride substrates

    SciTech Connect

    Kayyalha, Morteza; Chen, Yong P.

    2015-09-14

    We have investigated the low frequency (f) flicker (also called 1/f) noise of single-layer graphene devices on h-BN (placed on SiO{sub 2}/Si) along with those on SiO{sub 2}/Si. We observe that the devices fabricated on h-BN have on average one order of magnitude lower noise amplitude compared with devices fabricated on SiO{sub 2}/Si despite having comparable mobilities at room temperature. We associate this noise reduction to the lower densities of impurities and trap sites in h-BN than in SiO{sub 2}. Furthermore, the gate voltage dependent noise amplitude shows a broad maximum at Dirac point for devices on h-BN, in contrast to the M-shaped behavior showing a minimum at Dirac point for devices on SiO{sub 2}, consistent with the reduced charge inhomogeneity (puddles) for graphene on h-BN. This study demonstrates that the use of h-BN as a substrate or dielectric can be a simple and efficient noise reduction technique valuable for electronic applications of graphene and other nanomaterials.

  4. Observation of reduced 1/f noise in graphene field effect transistors on boron nitride substrates

    NASA Astrophysics Data System (ADS)

    Kayyalha, Morteza; Chen, Yong P.

    2015-09-01

    We have investigated the low frequency (f) flicker (also called 1/f) noise of single-layer graphene devices on h-BN (placed on SiO2/Si) along with those on SiO2/Si. We observe that the devices fabricated on h-BN have on average one order of magnitude lower noise amplitude compared with devices fabricated on SiO2/Si despite having comparable mobilities at room temperature. We associate this noise reduction to the lower densities of impurities and trap sites in h-BN than in SiO2. Furthermore, the gate voltage dependent noise amplitude shows a broad maximum at Dirac point for devices on h-BN, in contrast to the M-shaped behavior showing a minimum at Dirac point for devices on SiO2, consistent with the reduced charge inhomogeneity (puddles) for graphene on h-BN. This study demonstrates that the use of h-BN as a substrate or dielectric can be a simple and efficient noise reduction technique valuable for electronic applications of graphene and other nanomaterials.

  5. Signal Amplification Technique (SAT): an approach for improving resolution and reducing image noise in computed tomography

    SciTech Connect

    Phelps, M.E.; Huang, S.C.; Hoffman, E.J.; Plummer, D.; Carson, R.

    1981-01-01

    Spatial resolution improvements in computed tomography (CT) have been limited by the large and unique error propagation properties of this technique. The desire to provide maximum image resolution has resulted in the use of reconstruction filter functions designed to produce tomographic images with resolution as close as possible to the intrinsic detector resolution. Thus, many CT systems produce images with excessive noise with the system resolution determined by the detector resolution rather than the reconstruction algorithm. CT is a rigorous mathematical technique which applies an increasing amplification to increasing spatial frequencies in the measured data. This mathematical approach to spatial frequency amplification cannot distinguish between signal and noise and therefore both are amplified equally. We report here a method in which tomographic resolution is improved by using very small detectors to selectively amplify the signal and not noise. Thus, this approach is referred to as the signal amplification technique (SAT). SAT can provide dramatic improvements in image resolution without increases in statistical noise or dose because increases in the cutoff frequency of the reconstruction algorithm are not required to improve image resolution. Alternatively, in cases where image counts are low, such as in rapid dynamic or receptor studies, statistical noise can be reduced by lowering the cutoff frequency while still maintaining the best possible image resolution. A possible system design for a positron CT system with SAT is described.

  6. Effect of discharge duct geometry on centrifugal fan performance and noise emission

    NASA Astrophysics Data System (ADS)

    Nelson, David A.; Butrymowicz, William; Thomas, Christopher

    2005-09-01

    Non-ideal inlet and discharge duct geometries can cause significant changes to both the aerodynamic performance (``fan curve'') and specific sound power emission of a fan. A proper understanding of actual installed performance, as well as a good estimate of the system backpressure curve, is critical to achieving flow and acoustic goals as well as other criteria such as power consumption, mass and volume. To this end a battery of ISO 10302 tests was performed on a blower assembly which supports the Advanced Animal Habitat, being developed by ORBITEC for deployment on the International Space Station. The blower assembly consists of (4) identical centrifugal fans that, amongst themselves and across two prototypes, incorporated several discharge geometries. The inlet geometries were identical in all cases. Thus by comparing the dimensionless pressure-flow and noise emission characteristics across the cases, significant insight into the nature and potential magnitude of these effects is gained.

  7. Reducing GHG emissions in the United States' transportation sector

    SciTech Connect

    Das, Sujit; Andress, David A; Nguyen, Tien

    2011-01-01

    Reducing GHG emissions in the U.S. transportation sector requires both the use of highly efficient propulsion systems and low carbon fuels. This study compares reduction potentials that might be achieved in 2060 for several advanced options including biofuels, hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and fuel cell electric vehicles (FCEV), assuming that technical and cost reduction targets are met and necessary fueling infrastructures are built. The study quantifies the extent of the reductions that can be achieved through increasing engine efficiency and transitioning to low-carbon fuels separately. Decarbonizing the fuels is essential for achieving large reductions in GHG emissions, and the study quantifies the reductions that can be achieved over a range of fuel carbon intensities. Although renewables will play a vital role, some combination of coal gasification with carbon capture and sequestration, and/or nuclear energy will likely be needed to enable very large reductions in carbon intensities for hydrogen and electricity. Biomass supply constraints do not allow major carbon emission reductions from biofuels alone; the value of biomass is that it can be combined with other solutions to help achieve significant results. Compared with gasoline, natural gas provides 20% reduction in GHG emissions in internal combustion engines and up to 50% reduction when used as a feedstock for producing hydrogen or electricity, making it a good transition fuel for electric propulsion drive trains. The material in this paper can be useful information to many other countries, including developing countries because of a common factor: the difficulty of finding sustainable, low-carbon, cost-competitive substitutes for petroleum fuels.

  8. Investigation of Fuel Nozzle Technologies to Reduce Gas Turbine Emissions

    NASA Astrophysics Data System (ADS)

    Antony Francis, Roger Neil

    With increasing requirements for reduced emissions from future gas turbines, a multitude of research is being conducted into fuel nozzles by gas turbine manufacturers. This thesis focuses on the development of a novel spill return nozzle, to improve combustion efficiency at starting and low power conditions -where combustion efficiency is often the poorest. The spill return nozzle has the advantage of being able to improve atomization performance and reduce internal coking potential, all while being a simple and durable design. The spill return nozzle tech- nology was subsequently applied to a design for an existing small gas turbine combustor, and its improvements over the existing nozzle were demonstrated. The proposed design was also extended to experimental testing in a simplified form. CAD drawings of the components for testing were made, and prototypes were built in plastic using a high accuracy 3D printer. Future work involves conducting experimental tests to validate results.

  9. Numerical and experimental investigation of a beveled trailing-edge flow field and noise emission

    NASA Astrophysics Data System (ADS)

    van der Velden, W. C. P.; Pröbsting, S.; van Zuijlen, A. H.; de Jong, A. T.; Guan, Y.; Morris, S. C.

    2016-12-01

    Efficient tools and methodology for the prediction of trailing-edge noise experience substantial interest within the wind turbine industry. In recent years, the Lattice Boltzmann Method has received increased attention for providing such an efficient alternative for the numerical solution of complex flow problems. Based on the fully explicit, transient, compressible solution of the Lattice Boltzmann Equation in combination with a Ffowcs-Williams and Hawking aeroacoustic analogy, an estimation of the acoustic radiation in the far field is obtained. To validate this methodology for the prediction of trailing-edge noise, the flow around a flat plate with an asymmetric 25° beveled trailing edge and obtuse corner in a low Mach number flow is analyzed. Flow field dynamics are compared to data obtained experimentally from Particle Image Velocimetry and Hot Wire Anemometry, and compare favorably in terms of mean velocity field and turbulent fluctuations. Moreover, the characteristics of the unsteady surface pressure, which are closely related to the acoustic emission, show good agreement between simulation and experiment. Finally, the prediction of the radiated sound is compared to the results obtained from acoustic phased array measurements in combination with a beamforming methodology. Vortex shedding results in a strong narrowband component centered at a constant Strouhal number in the acoustic spectrum. At higher frequency, a good agreement between simulation and experiment for the broadband noise component is obtained and a typical cardioid-like directivity is recovered.

  10. Influence of sound-conditioning on noise-induced susceptibility of distortion-product otoacoustic emissions.

    PubMed

    Luebke, Anne E; Stagner, Barden B; Martin, Glen K; Lonsbury-Martin, Brenda L

    2015-07-01

    Cochlear damage caused by loud sounds can be attenuated by "sound-conditioning" methods. The amount of adaptation for distortion product otoacoustic emissions (DPOAEs) measured in alert rabbits previously predicted an ear's susceptibility to a subsequent noise exposure. The present study investigated if sound-conditioning influenced the robustness of such DPOAE adaptation, and if such conditioning elicited more protection by increasing the amount of DPOAE adaptation. Toward this end, rabbits were divided into two study groups: (1) experimental animals exposed to a sound-conditioning protocol, and (2) unconditioned control animals. After base-line measures, all rabbits were exposed to an overstimulation paradigm consisting of an octave band noise, and then re-assessed 3 weeks post-exposure to determine permanent changes in DPOAEs. A major result was that prior sound-conditioning protected reductions in DPOAE levels by an average of 10-15 dB. However, DPOAE adaptation decreased with sound-conditioning, so that such conditioning was no longer related to noise-induced reductions in DPOAEs. Together, these findings suggest that sound-conditioning affected neural pathways other than those that likely mediate DPOAE adaptation (e.g., medial olivocochlear efferent and/or middle-ear muscle reflexes).

  11. Environmentally Responsible Aviation: Propulsion Research to Enable Fuel Burn, Noise and Emissions Reduction

    NASA Technical Reports Server (NTRS)

    Van Zante, Dale E.; Suder, Kenneth L.

    2015-01-01

    The NASA Environmentally Responsible Aviation (ERA) program is maturing technologies to enable simultaneous reduction of fuel burn, noise and emissions from an aircraft engine system. Three engine related Integrated Technology Demonstrations (ITDs) have been completed at Glenn Research Center in collaboration with Pratt Whitney, General Electric and the Federal Aviation Administration. The engine technologies being matured are a low NOx, fuel flexible combustor in partnership with Pratt Whitney, an ultra-high bypass, ducted propulsor system in partnership with Pratt Whitney FAA and high pressure ratio, front-stage core compressor technology in partnership with General Electric. The technical rationale, test configurations and overall results from the test series in each ITD are described. ERA is using system analysis to project the benefits of the ITD technologies on potential aircraft systems in the 2025 timeframe. Data from the ITD experiments were used to guide the system analysis assumptions. Results from the current assessments for fuel burn, noise and oxides of nitrogen emissions are presented.

  12. Environmentally Responsible Aviation: Propulsion Research to Enable Fuel Burn, Noise and Emissions Reduction

    NASA Technical Reports Server (NTRS)

    Van Zante, Dale; Suder, Kenneth

    2015-01-01

    The NASA Environmentally Responsible Aviation (ERA) program is maturing technologies to enable simultaneous reduction of fuel burn, noise and emissions from an aircraft engine system. Three engine related Integrated Technology Demonstrations (ITDs) have been completed at Glenn Research Center in collaboration with Pratt Whitney, General Electric and the Federal Aviation Administration. The engine technologies being matured are: a low NOx, fuel flexible combustor in partnership with Pratt Whitney; an ultra-high bypass, ducted propulsor system in partnership with Pratt Whitney and FAA; and high pressure ratio, front-stage core compressor technology in partnership with General Electric. The technical rationale, test configurations and overall results from the test series in each ITD are described. ERA is using system analysis to project the benefits of the ITD technologies on potential aircraft systems in the 2025 timeframe. Data from the ITD experiments were used to guide the system analysis assumptions. Results from the current assessments for fuel burn, noise and oxides of nitrogen emissions are presented.

  13. Theoretical investigation of the effects of the cushion on reducing underwater noise from offshore pile driving.

    PubMed

    Deng, Qingpeng; Jiang, Weikang; Zhang, Wenzheng

    2016-10-01

    Offshore pile driving noise has gained increasing attention due to its adverse influence on marine animals. Two models are established to investigate the influence of the cushion on the underwater noise from pile driving. A one-dimensional nonlinear finite difference model is developed to compute the impact force and the soil penetration. The radiated sound pressure is predicted by the second model based on a semi-analytical variational formulation. For the examined pile, a proper cushion can significantly dampen the high-frequency impact force and reduce the peak of the sound pressure. It is found that there exists a stiffness range within which the decline of the cushion stiffness effectively reduces the single sound exposure level but hardly increases the required hammer blows to achieve a certain penetration depth.

  14. Method and Apparatus for Reducing Noise from Near Ocean Surface Sources

    DTIC Science & Technology

    2001-10-01

    reducing the acoustic noise from near-surface 4 sources using an array processing technique that utilizes 5 Multiple Signal Classification ( MUSIC ...sources without 13 degrading the signal level and quality of the TOI. The present 14 invention utilizes a unique application of the MUSIC beamforming...specific algorithm that utilizes a 5 MUSIC technique and estimates the direction of arrival (DOA) of 6 the acoustic signal signals and generates output

  15. Targeting and Reducing Noise Trauma-Induced Tinnitus and Hearing Loss

    DTIC Science & Technology

    2010-08-01

    various times (right away to several days) and with different regimens ( pulse or taper) to rats following noise-trauma. We report on the effect of...reliable presence of another stimulus just before the burst will reduce the startle reflex (this is called pre- pulse inhibition). In our case, a...randomly. For a rat with normal hearing the ratio of gap to nogap startle reflex (whether measured by maximal amplitude or RMS of the startle

  16. Reducing uncertainty in methane emission estimates from permafrost peatlands

    NASA Astrophysics Data System (ADS)

    Christensen, Torben R.

    2016-04-01

    Reducing uncertainty in methane emission estimates from permafrost peatlands Torben R. Christensen1,2 and coworkers 1) Department of Physical Geography and Ecosystem Science, Lund University, Sweden 2) Arctic Research Centre, Aarhus University, Denmark Depending on factors including temperature, snow duration and soil moisture conditions, emissions of the greenhouse gas methane from permafrost peatlands can vary by factors of 2-4 between years. This variability is clear in atmospheric measurements of the gas, but a lack of ground-based data is making it hard to locate the methane sources responsible. Methane monitoring in the Arctic is expensive, requiring sophisticated analysis equipment such as power requiring laser spectrometer analysis made in remote places. This also puts demands on the logistics where infrastructures and field stations that offer line-power in the field are in high demand but very rarely found. Research projects therefore typically focus on one site, and run for a year or two. Longer term monitoring programs, which document climate, hydrology, phenology and population dynamics of birds and mammals, rarely include carbon fluxes since it is technically challenging to measure. One that does is the Greenland Ecosystem Monitoring program that started at the Zackenberg research station, which has recorded substantial methane flux variations for almost a decade in North-east Greenland. Such multi-year studies show that, while there is some connection between the amounts of methane released from one year to the next, accurate forecasting is difficult. They also highlight the importance of extending monitoring beyond the growing period into the frozen season, both in spring and autumn. A spatially distributed network of long-term monitoring stations in the Arctic, with consistency between measurements, is badly needed to improve this situation. Productive methane 'hot spots', many sporadic, have also been identified in recent studies. By ventilating

  17. Effective noise-suppressed and artifact-reduced reconstruction of SPECT data using a preconditioned alternating projection algorithm

    PubMed Central

    Li, Si; Zhang, Jiahan; Krol, Andrzej; Schmidtlein, C. Ross; Vogelsang, Levon; Shen, Lixin; Lipson, Edward; Feiglin, David; Xu, Yuesheng

    2015-01-01

    Purpose: The authors have recently developed a preconditioned alternating projection algorithm (PAPA) with total variation (TV) regularizer for solving the penalized-likelihood optimization model for single-photon emission computed tomography (SPECT) reconstruction. This algorithm belongs to a novel class of fixed-point proximity methods. The goal of this work is to investigate how PAPA performs while dealing with realistic noisy SPECT data, to compare its performance with more conventional methods, and to address issues with TV artifacts by proposing a novel form of the algorithm invoking high-order TV regularization, denoted as HOTV-PAPA, which has been explored and studied extensively in the present work. Methods: Using Monte Carlo methods, the authors simulate noisy SPECT data from two water cylinders; one contains lumpy “warm” background and “hot” lesions of various sizes with Gaussian activity distribution, and the other is a reference cylinder without hot lesions. The authors study the performance of HOTV-PAPA and compare it with PAPA using first-order TV regularization (TV-PAPA), the Panin–Zeng–Gullberg one-step-late method with TV regularization (TV-OSL), and an expectation–maximization algorithm with Gaussian postfilter (GPF-EM). The authors select penalty-weights (hyperparameters) by qualitatively balancing the trade-off between resolution and image noise separately for TV-PAPA and TV-OSL. However, the authors arrived at the same penalty-weight value for both of them. The authors set the first penalty-weight in HOTV-PAPA equal to the optimal penalty-weight found for TV-PAPA. The second penalty-weight needed for HOTV-PAPA is tuned by balancing resolution and the severity of staircase artifacts. The authors adjust the Gaussian postfilter to approximately match the local point spread function of GPF-EM and HOTV-PAPA. The authors examine hot lesion detectability, study local spatial resolution, analyze background noise properties, estimate mean

  18. Effective noise-suppressed and artifact-reduced reconstruction of SPECT data using a preconditioned alternating projection algorithm

    SciTech Connect

    Li, Si; Xu, Yuesheng; Zhang, Jiahan; Lipson, Edward; Krol, Andrzej; Feiglin, David; Schmidtlein, C. Ross; Vogelsang, Levon; Shen, Lixin

    2015-08-15

    Purpose: The authors have recently developed a preconditioned alternating projection algorithm (PAPA) with total variation (TV) regularizer for solving the penalized-likelihood optimization model for single-photon emission computed tomography (SPECT) reconstruction. This algorithm belongs to a novel class of fixed-point proximity methods. The goal of this work is to investigate how PAPA performs while dealing with realistic noisy SPECT data, to compare its performance with more conventional methods, and to address issues with TV artifacts by proposing a novel form of the algorithm invoking high-order TV regularization, denoted as HOTV-PAPA, which has been explored and studied extensively in the present work. Methods: Using Monte Carlo methods, the authors simulate noisy SPECT data from two water cylinders; one contains lumpy “warm” background and “hot” lesions of various sizes with Gaussian activity distribution, and the other is a reference cylinder without hot lesions. The authors study the performance of HOTV-PAPA and compare it with PAPA using first-order TV regularization (TV-PAPA), the Panin–Zeng–Gullberg one-step-late method with TV regularization (TV-OSL), and an expectation–maximization algorithm with Gaussian postfilter (GPF-EM). The authors select penalty-weights (hyperparameters) by qualitatively balancing the trade-off between resolution and image noise separately for TV-PAPA and TV-OSL. However, the authors arrived at the same penalty-weight value for both of them. The authors set the first penalty-weight in HOTV-PAPA equal to the optimal penalty-weight found for TV-PAPA. The second penalty-weight needed for HOTV-PAPA is tuned by balancing resolution and the severity of staircase artifacts. The authors adjust the Gaussian postfilter to approximately match the local point spread function of GPF-EM and HOTV-PAPA. The authors examine hot lesion detectability, study local spatial resolution, analyze background noise properties, estimate mean

  19. Effective noise-suppressed and artifact-reduced reconstruction of SPECT data using a preconditioned alternating projection algorithm.

    PubMed

    Li, Si; Zhang, Jiahan; Krol, Andrzej; Schmidtlein, C Ross; Vogelsang, Levon; Shen, Lixin; Lipson, Edward; Feiglin, David; Xu, Yuesheng

    2015-08-01

    The authors have recently developed a preconditioned alternating projection algorithm (PAPA) with total variation (TV) regularizer for solving the penalized-likelihood optimization model for single-photon emission computed tomography (SPECT) reconstruction. This algorithm belongs to a novel class of fixed-point proximity methods. The goal of this work is to investigate how PAPA performs while dealing with realistic noisy SPECT data, to compare its performance with more conventional methods, and to address issues with TV artifacts by proposing a novel form of the algorithm invoking high-order TV regularization, denoted as HOTV-PAPA, which has been explored and studied extensively in the present work. Using Monte Carlo methods, the authors simulate noisy SPECT data from two water cylinders; one contains lumpy "warm" background and "hot" lesions of various sizes with Gaussian activity distribution, and the other is a reference cylinder without hot lesions. The authors study the performance of HOTV-PAPA and compare it with PAPA using first-order TV regularization (TV-PAPA), the Panin-Zeng-Gullberg one-step-late method with TV regularization (TV-OSL), and an expectation-maximization algorithm with Gaussian postfilter (GPF-EM). The authors select penalty-weights (hyperparameters) by qualitatively balancing the trade-off between resolution and image noise separately for TV-PAPA and TV-OSL. However, the authors arrived at the same penalty-weight value for both of them. The authors set the first penalty-weight in HOTV-PAPA equal to the optimal penalty-weight found for TV-PAPA. The second penalty-weight needed for HOTV-PAPA is tuned by balancing resolution and the severity of staircase artifacts. The authors adjust the Gaussian postfilter to approximately match the local point spread function of GPF-EM and HOTV-PAPA. The authors examine hot lesion detectability, study local spatial resolution, analyze background noise properties, estimate mean square errors (MSEs), and

  20. Simultaneous Measurement of Noise-Activated Middle-Ear Muscle Reflex and Stimulus Frequency Otoacoustic Emissions

    PubMed Central

    Keefe, Douglas H.

    2006-01-01

    Otoacoustic emissions serve as a noninvasive probe of the medial olivocochlear (MOC) reflex. Stimulus frequency otoacoustic emissions (SFOAEs) elicited by a low-level probe tone may be the optimal type of emission for studying MOC effects because at low levels, the probe itself does not elicit the MOC reflex [Guinan et al. (2003) J. Assoc. Res. Otolaryngol. 4:521]. Based on anatomical considerations, the MOC reflex activated by ipsilateral acoustic stimulation (mediated by the crossed olivocochlear bundle) is predicted to be stronger than the reflex to contralateral stimulation. Broadband noise is an effective activator of the MOC reflex; however, it is also an effective activator of the middle-ear muscle (MEM) reflex, which can make results difficult to interpret. The MEM reflex may be activated at lower levels than measured clinically, and most previous human studies have not explicitly included measurements to rule out MEM reflex contamination. The current study addressed these issues using a higher-frequency SFOAE probe tone to test for cochlear changes mediated by the MOC reflex, while simultaneously monitoring the MEM reflex using a low-frequency probe tone. Broadband notched noise was presented ipsilaterally at various levels to elicit probe-tone shifts. Measurements are reported for 15 normal-hearing subjects. With the higher-frequency probe near 1.5 kHz, only 20% of subjects showed shifts consistent with an MOC reflex in the absence of an MEM-induced shift. With the higher-frequency probe near 3.5 kHz, up to 40% of subjects showed shifts in the absence of an MEM-induced shift. However, these responses had longer time courses than expected for MOC-induced shifts, and may have been dominated by other cochlear processes, rather than MOC reflex. These results suggest caution in the interpretation of effects observed using ipsilaterally presented acoustic activators intended to excite the MOC reflex. PMID:16568366

  1. Simultaneous measurement of noise-activated middle-ear muscle reflex and stimulus frequency otoacoustic emissions.

    PubMed

    Goodman, Shawn S; Keefe, Douglas H

    2006-06-01

    Otoacoustic emissions serve as a noninvasive probe of the medial olivocochlear (MOC) reflex. Stimulus frequency otoacoustic emissions (SFOAEs) elicited by a low-level probe tone may be the optimal type of emission for studying MOC effects because at low levels, the probe itself does not elicit the MOC reflex [Guinan et al. (2003) J. Assoc. Res. Otolaryngol. 4:521]. Based on anatomical considerations, the MOC reflex activated by ipsilateral acoustic stimulation (mediated by the crossed olivocochlear bundle) is predicted to be stronger than the reflex to contralateral stimulation. Broadband noise is an effective activator of the MOC reflex; however, it is also an effective activator of the middle-ear muscle (MEM) reflex, which can make results difficult to interpret. The MEM reflex may be activated at lower levels than measured clinically, and most previous human studies have not explicitly included measurements to rule out MEM reflex contamination. The current study addressed these issues using a higher-frequency SFOAE probe tone to test for cochlear changes mediated by the MOC reflex, while simultaneously monitoring the MEM reflex using a low-frequency probe tone. Broadband notched noise was presented ipsilaterally at various levels to elicit probe-tone shifts. Measurements are reported for 15 normal-hearing subjects. With the higher-frequency probe near 1.5 kHz, only 20% of subjects showed shifts consistent with an MOC reflex in the absence of an MEM-induced shift. With the higher-frequency probe near 3.5 kHz, up to 40% of subjects showed shifts in the absence of an MEM-induced shift. However, these responses had longer time courses than expected for MOC-induced shifts, and may have been dominated by other cochlear processes, rather than MOC reflex. These results suggest caution in the interpretation of effects observed using ipsilaterally presented acoustic activators intended to excite the MOC reflex.

  2. A research program to reduce interior noise in general aviation airplanes: Noise reduction through a cavity-backed flexible plate

    NASA Technical Reports Server (NTRS)

    Roskam, J.; Vandam, C. P. G.

    1978-01-01

    A prediction method is reported for noise reduction through a cavity-backed panel. The analysis takes into account only cavity modes in one direction. The results of this analysis were to find the effect of acoustic stiffness of a backing cavity on the panel behavior. The resulting changes in the noise reduction through the panel are significant.

  3. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    DOE PAGES

    Tobias, B.; Domier, C. W.; Luhmann, Jr., N. C.; ...

    2016-07-25

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads tomore » 10x improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). As a result, implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.« less

  4. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    SciTech Connect

    Tobias, B.; Domier, C. W.; Luhmann, Jr., N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A. -V.; Wang, Y.

    2016-07-25

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10x improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). As a result, implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  5. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    SciTech Connect

    Tobias, B.; Domier, C. W.; Luhmann, N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A.-V.; Wang, Y.

    2016-11-15

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50–150 GHz) to an intermediate frequency (IF) band (e.g. 0.1–18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10× improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). Implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  6. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    SciTech Connect

    Tobias, B.; Domier, C. W.; Luhmann, Jr., N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A. -V.; Wang, Y.

    2016-07-25

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10x improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). As a result, implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  7. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    NASA Astrophysics Data System (ADS)

    Tobias, B.; Domier, C. W.; Luhmann, N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A.-V.; Wang, Y.

    2016-11-01

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10× improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). Implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  8. Acoustic emissions of digital data video projectors- Investigating noise sources and their change during product aging

    NASA Astrophysics Data System (ADS)

    White, Michael Shane

    2005-09-01

    Acoustic emission testing continues to be a growing part of IT and telecommunication product design, as product noise is increasingly becoming a differentiator in the marketplace. This is especially true for digital/video display companies, such as InFocus Corporation, considering the market shift of these products to the home entertainment consumer as retail prices drop and performance factors increase. Projectors and displays using Digital Light Processing(tm) [DLP(tm)] technology incorporate a device known as a ColorWheel(tm) to generate the colors displayed at each pixel in the image. These ColorWheel(tm) devices spin at very high speeds and can generate high-frequency tones not typically heard in liquid crystal displays and other display technologies. Also, acoustic emission testing typically occurs at the beginning of product life and is a measure of acoustic energy emitted at this point in the lifecycle. Since the product is designed to be used over a long period of time, there is concern as to whether the acoustic emissions change over the lifecycle of the product, whether these changes will result in a level of nuisance to the average customer, and does this nuisance begin to develop prior to the intended lifetime of the product.

  9. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry.

    PubMed

    Tobias, B; Domier, C W; Luhmann, N C; Luo, C; Mamidanna, M; Phan, T; Pham, A-V; Wang, Y

    2016-11-01

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10× improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). Implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  10. Reducing Uncertainty in Methane Emission Estimates from Permafrost Environments

    NASA Astrophysics Data System (ADS)

    Christensen, T. R.; Mastepanov, M.; Lund, M.; Tamstorf, M. P.; Parmentier, F. J. W.; Rysgård, S.; Lilienthal, A. J.

    2014-12-01

    emissions are of a scale that still is in need of being reconciled with the atmospheric record. This presentation will give an overview of novel approaches including robot techniques ground-, boat- and airborne-based to reduce uncertainty in particular in relation to these 'hot spot' emissions.

  11. Approaches for the design of reduced toxicant emission cigarettes.

    PubMed

    Dittrich, David J; Fieblekorn, Richard T; Bevan, Michael J; Rushforth, David; Murphy, James J; Ashley, Madeleine; McAdam, Kevin G; Liu, Chuan; Proctor, Christopher J

    2014-01-01

    Cigarette smoking causes serious diseases through frequent and prolonged exposure to toxicants. Technologies are being developed to reduce smokers' toxicant exposure, including filter adsorbents, tobacco treatments and substitutes. This study examined the effect of modifications to filter ventilation, variations in cigarette circumference and active charcoal filter length and loading, as well as combinations of these features in a reduced-toxicant prototype (RTP) cigarette, on the yields of toxicants in cigarette smoke. An air-dilution mechanism, called split-tipping, was developed in which a band of porous paper in the centre of the filter tipping functions to minimise the loss of effective filter ventilation that occurs at the high flow rates encountered during human-smoking, and to facilitate the diffusional loss of volatile toxicants. As compared with conventional filter ventilation cigarettes, split-tipping reduced tar and volatile smoke constituent emissions under high flow rate machine-smoking conditions, most notably for products with a 1-mg ISO tar yield. Furthermore, mouth level exposure (MLE) to tar and nicotine was reduced among smokers of 1-mg ISO tar cigarettes in comparison to smokers of cigarettes with traditional filter ventilation. For higher ISO tar level cigarettes, however, there were no significant reductions in MLE. Smaller cigarette circumferences reduced sidestream toxicant yields and modified the balance of mainstream smoke chemistry with reduced levels of aromatic amines and benzo[a]pyrene but increased yields of formaldehyde. Smaller circumference cigarettes also had lower mainstream yields of volatile toxicants. Longer cigarette filters containing increased levels of high-activity carbon (HAC) showed reduced machine-smoking yields of volatile toxicants: with up to 97% removal for some volatile toxicants at higher HAC loadings. Split-tipping was combined with optimal filter length and cigarette circumference in an RTP cigarette that gave

  12. Nutrient-Enhanced Diet Reduces Noise-Induced Damage to the Inner Ear and Hearing Loss

    PubMed Central

    Le Prell, C. G.; Gagnon, P. M; Bennett, D. C.; Ohlemiller, K. K.

    2011-01-01

    Oxidative stress has been broadly implicated as a cause of cell death and neural degeneration in multiple disease conditions; however, the evidence for successful intervention with dietary antioxidant manipulations has been mixed. In this study, we investigated the potential for protection of cells in the inner ear using a dietary supplement with multiple antioxidant components, selected for their potential interactive effectiveness. Protection against permanent threshold shift (PTS) was observed in CBA/J mice maintained on a diet supplemented with a combination of β-carotene, vitamins C and E, and magnesium when compared to PTS in control mice maintained on a nutritionally complete control diet. Although hair cell survival was not enhanced, noise-induced loss of Type II fibrocytes in the lateral wall was significantly reduced (p<0.05), and there was a trend towards less noise-induced loss in strial cell density in animals maintained on the supplemented diet. Taken together, our data suggest that pre-noise oral treatment with the high-nutrient diet can protect cells in the inner ear and reduce PTS in mice. Demonstration of functional and morphological preservation of cells in the inner ear with oral administration of this antioxidant supplemented diet supports the possibility of translation to human patients, and suggests an opportunity to evaluate antioxidant protection in mouse models of oxidative stress-related disease and pathology. PMID:21708355

  13. On Certain New Methodology for Reducing Sensor and Readout Electronics Circuitry Noise in Digital Domain

    NASA Technical Reports Server (NTRS)

    Kizhner, Semion; Miko, Joseph; Bradley, Damon; Heinzen, Katherine

    2008-01-01

    NASA Hubble Space Telescope (HST) and upcoming cosmology science missions carry instruments with multiple focal planes populated with many large sensor detector arrays. These sensors are passively cooled to low temperatures for low-level light (L3) and near-infrared (NIR) signal detection, and the sensor readout electronics circuitry must perform at extremely low noise levels to enable new required science measurements. Because we are at the technological edge of enhanced performance for sensors and readout electronics circuitry, as determined by thermal noise level at given temperature in analog domain, we must find new ways of further compensating for the noise in the signal digital domain. To facilitate this new approach, state-of-the-art sensors are augmented at their array hardware boundaries by non-illuminated reference pixels, which can be used to reduce noise attributed to sensors. There are a few proposed methodologies of processing in the digital domain the information carried by reference pixels, as employed by the Hubble Space Telescope and the James Webb Space Telescope Projects. These methods involve using spatial and temporal statistical parameters derived from boundary reference pixel information to enhance the active (non-reference) pixel signals. To make a step beyond this heritage methodology, we apply the NASA-developed technology known as the Hilbert- Huang Transform Data Processing System (HHT-DPS) for reference pixel information processing and its utilization in reconfigurable hardware on-board a spaceflight instrument or post-processing on the ground. The methodology examines signal processing for a 2-D domain, in which high-variance components of the thermal noise are carried by both active and reference pixels, similar to that in processing of low-voltage differential signals and subtraction of a single analog reference pixel from all active pixels on the sensor. Heritage methods using the aforementioned statistical parameters in the

  14. Observations of correlated broadband electrostatic noise and electron-cyclotron emissions in the plasma sheet. Technical report

    SciTech Connect

    Roeder, J.L.; Angelopoulos, V.; Baumjohann, W.; Anderson, R.R.

    1991-11-15

    Electric field wave observations in the central plasma sheet of the earth's magnetosphere show the correlated occurrence of broadband electrostatic noise and electrostatic electron cyclotron harmonic emissions. A model is proposed in which the broadband emissions are electron acoustic waves generated by an observed low energy electron beam, and the cyclotron emissions are generated by the hot electron loss cone instability. The high degree of correlation between the two emissions is provided in the model by the presence of the cold electron beam population, which allows both of the plasma instabilities to grow.

  15. Inverting seismic noise cross-correlations for noise source distribution: A step towards reducing source-induced bias in seismic noise interferometry

    NASA Astrophysics Data System (ADS)

    Ermert, Laura; Afanasiev, Michael; Sager, Korbinian; Gokhberg, Alexey; Fichtner, Andreas

    2016-04-01

    We report on the ongoing development of a new inversion method for the space- and time-dependent power spectral density distribution of ambient seismic noise sources. The method, once complete, will mainly serve two purposes: First, it will allow us to construct more realistic forward models for noise cross-correlation waveforms, thereby opening new possibilities for waveform imaging by ambient noise tomography. Second, it may provide new insights about the properties of ambient noise sources, complementing studies based on beamforming or numerical modeling of noise based on oceanographic observations. To invert for noise sources, we consider surface wave signal energy measurements on the 'causal' (station A to B) and on the 'acausal' (station B to A) correlation branch, and the ratio between them. These and similar measurements have proven useful for locating noise sources using cross-correlations in several past studies. The inversion procedure is the following: We construct correlation forward models based on Green's functions from a spectral element wave propagation code. To construct these models efficiently, we use source-receiver reciprocity and assume spatial uncorrelation of noise sources. In such a setting, correlations can be calculated from a pre-computed set of Green's functions between the seismic receivers and sources located at the Earth's surface. We then calculate spatial sensitivity kernels for the noise source distribution with respect to the correlation signal energy measurements. These in turn allow us to construct a misfit gradient and optimize the source distribution model to fit our observed cross-correlation signal energies or energy ratios. We will present the workflow for calculation of the forward model and sensitivity kernels, as well as results for both forward modeling and kernels for an example data set of long-period noise or 'hum' at a global scale. We will also provide an outlook on the noise source inversion considering the

  16. Environmental Stimulation Does Not Reduce Impulsive Choice in ADHD: A "Pink Noise" Study.

    PubMed

    Metin, Baris; Roeyers, Herbert; Wiersema, Jan R; van der Meere, Jaap J; Gasthuys, Roos; Sonuga-Barke, Edmund

    2016-01-01

    The preference for sooner smaller over larger later rewards is a prominent manifestation of impulsivity in ADHD. According to the State Regulation Deficit (SRD) model, this impulsive choice is the result of impaired regulation of arousal level and can be alleviated by adding environmental stimulation to increase levels of arousal. To test this prediction, we studied the effects of adding background "pink noise" on impulsive choice using a classical and new adjusting choice delay task in a sample of 25 children with ADHD and 28 controls. Children with ADHD made more impulsive choices than controls. Adding noise did not reduce impulsive choice in ADHD. The findings add to the existing evidence on impulsive choice in ADHD, but no evidence is found for the SRD model's explanation of this behavioral style. Alternative explanations for impulsive choice in ADHD are discussed. © The Author(s) 2013.

  17. A numerical method for reducing the random noise in a two-dimensional waveform

    SciTech Connect

    Levy, A.J.

    1991-01-23

    This invention is comprised of a method for reducing random noise in a two-dimensional waveform having an irregular curvature includes the steps of selecting a plurality of points initially positioned at preselected locations on the waveform. For each point selected, the straight line is found which connects it to the midpoint between its neighboring points. A new location for the point is calculated to lie on the straight line a fraction of the distance between the initial location of the point and the midpoint. This process is repeated for each point positioned on the waveform. After a single iteration of the method is completed, the entire process is repeated a predetermined number of times to identify final calculated locations for the plurality of points selected. The final calculated locations of the points are then connected to form a relatively random noise-free waveform having a substantially smooth curvature.

  18. Noise reduction in an optical emission spectrometer with rotating diffraction grating

    NASA Astrophysics Data System (ADS)

    Litwin, Dariusz; Sitarek, Stefan; Tyburska-Staniewska, Anna; Ramsza, Andrzej; Wikliński, Piotr; Kowalski, Henryk A.; Mazur, Grzegorz; Rzeszut, Janusz; Dałek, Łukasz; Galas, Jacek; Daszkiewicz, Marek

    2016-12-01

    The paper concerns the development of an optical emission spectrometer with a helium microwave rotating plasma as the excitation source which is an alternative to ICP spectrometers. In the new solution helium is used as the plasma and carrier gases, which helps to determine elements such as halogens and some non-metals. The new system should demonstrate decreased operating costs i.e. the flow of 1L He/min compared to about 15L Ar/min for ICP. Its spectral range is within 165 nm - 840 nm, sensitivity at the level of ppb and spectral resolution is equal to 0.01 nm. The system uses a set of two photomultipliers for VIS and UV regions. The entire spectrum is collected during a single rotation of the diffraction gratings. The paper describes the collection of algorithms developed to decrease noise and smooth spectral data.

  19. Identifying the Origin of Effects of Contralateral Noise on Transient Evoked Otoacoustic Emissions in Unanesthetized Mice.

    PubMed

    Xu, Yingyue; Cheatham, Mary Ann; Siegel, Jonathan H

    2017-08-01

    Descending neural pathways in the mammalian auditory system are known to modulate the function of the peripheral auditory system. These pathways include the medial olivocochlear (MOC) efferent innervation to outer hair cells (OHCs) and the acoustic reflex pathways mediating middle ear muscle (MEM) contractions. Based on measurements in humans (Marks and Siegel, companion paper), we applied a sensitive method to attempt to differentiate MEM and MOC reflexes using contralateral acoustic stimulation in mice under different levels of anesthesia. Separation of these effects is based on the knowledge that OHC-generated transient evoked otoacoustic emissions (TEOAE) are delayed relative to the stimulus, and that the MOC reflex affects the emission through its innervation of OHC. In contrast, the MEM-mediated changes in middle ear reflectance alter both the stimulus (with a short delay) and the emission. Using this approach, time averages to transient stimuli were evaluated to determine if thresholds for a contralateral effect on the delayed emission, indicating potential MOC activation, could be observed in the absence of a change in the stimulus pressure. This outcome was not observed in the majority of cases. There were also no statistically significant differences between MEM and putative MOC thresholds, and variability was high for both thresholds regardless of anesthesia level. Since the two reflex pathways could not be differentiated on the basis of activation thresholds, it was concluded that the MEM reflex dominates changes in TEOAEs induced by contralateral noise. This result complicates the identification of purely MOC-induced changes on OAEs in mice unless the MEM reflex is inactivated surgically or pharmacologically.

  20. Log-Likelihood Method of Reducing Noise in CRISM Along-Track Oversampled Hyperspectral Images

    NASA Astrophysics Data System (ADS)

    Kreisch, C.; Arvidson, R. E.; O'Sullivan, J. A.; Fraeman, A. A.

    2014-12-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) began taking Along-Track Oversampled (ATO) observations in 2010 to obtain super-resolution hyperspectral images, with spatial resolutions in the along-track direction of as small as ~5 m/pixel. We present a new method to both process and reduce noise in the ATOs. We developed a log-likelihood algorithm to determine the most likely estimate of the actual Martian surface given the CRISM spectral radiance measurements and spatial and spectral transfer functions (TF). We assume the spatial TF is given by a 2D Gaussian and use the asymmetric Gaussian spectral TF given in the CRISM documentation. The log-likelihood method reduces Poisson noise in the spectrum for a given hyperspectral pixel, allowing for identification of subtle spectral absorptions otherwise lost in noise. We assume that the data are Poisson distributed and that the mean μ is given by a blurred version of the actual scene c. The CRISM ATO is this blurred version. It is more efficient to maximize the log of a function rather than the function itself, so we compute the image c that maximizes the log-likelihood function for the data. We begin with an initial guess for the projected, estimated scene c and have the freedom to choose any reasonable output pixel size. To forward project, we convolve the spatial TF with c and then convolve the spectral TF with the output. The result is a simulation of the measured ATO. We divide the CRISM ATO by this simulated scene to obtain the error, and then we backproject the error into dimensions of c by applying transposes of the TFs. Finally, we update our guess for the actual scene by multiplying c by the backprojected error. We iterate until convergence. We focus our analysis on recent ATOs of Gale Crater to illustrate the advantages of the method. We will also present a combined Poisson and Gaussian noise iterative approach with regularization and results for reducing noise in CRISM data.

  1. Relationship between leisure noise exposure and otoacoustic emissions in a young Asian population.

    PubMed

    Lee, Gary Jek Chong; Lim, Ming Yann; Kuan, Angeline Yi Wei; Teo, Joshua Han Wei; Tan, Hui Guang; Low, Wong Kein

    2014-07-01

    This study compared the otoacoustic emissions amplitudes of Asian youths at risk of leisure noise exposure through the use of portable music players with their less exposed counterparts. A listening habit survey was conducted. Subjects were divided into two groups for analysis. A subject was placed within the high risk group if he/she reported listening to music at near maximum volume and had a physical measurement of his/her preferred listening level recorded at > 85 dBA. DPOAE and TEOAE levels were measured and compared between the two groups. A total of 1928 students from a tertiary educational institution in Singapore. TEOAE levels were found to be significantly lower in the high risk group at 4 kHz. DPOAE levels were also found to be significantly depressed in the high risk group at 1, 2, 3, and 4 kHz with the largest mean difference at 4 kHz. A four-way ANOVA carried out for OAE amplitudes using gender, ear laterality, risk profile, and years of usage as independent factors also showed that risk profile was a significant factor in determining the OAE amplitude at 4 kHz. We have demonstrated that both DPAOE and TEOAE values are diminished in the Asian subjects at high risk for noise exposure.

  2. Noise addendum experimental clean combustor program, phase 1

    NASA Technical Reports Server (NTRS)

    Sofrin, T. G.; Ross, D. A.

    1975-01-01

    The development of advanced CTOL aircraft engines with reduced exhaust emissions is discussed. Combustor noise information provided during the basic emissions program and used to advantage in securing reduced levels of combustion noise is included. Results are presented of internal pressure transducer measurements made during the scheduled emissions test program on ten configurations involving variations of three basic combustor designs.

  3. Selective attention reduces physiological noise in the external ear canals of humans. II: Visual attention

    PubMed Central

    Walsh, Kyle P.; Pasanen, Edward G.; McFadden, Dennis

    2014-01-01

    Human subjects performed in several behavioral conditions requiring, or not requiring, selective attention to visual stimuli. Specifically, the attentional task was to recognize strings of digits that had been presented visually. A nonlinear version of the stimulus-frequency otoacoustic emission (SFOAE), called the nSFOAE, was collected during the visual presentation of the digits. The segment of the physiological response discussed here occurred during brief silent periods immediately following the SFOAE-evoking stimuli. For all subjects tested, the physiological-noise magnitudes were substantially weaker (less noisy) during the tasks requiring the most visual attention. Effect sizes for the differences were >2.0. Our interpretation is that cortico-olivo influences adjusted the magnitude of efferent activation during the SFOAE-evoking stimulation depending upon the attention task in effect, and then that magnitude of efferent activation persisted throughout the silent period where it also modulated the physiological noise present. Because the results were highly similar to those obtained when the behavioral conditions involved auditory attention, similar mechanisms appear to operate both across modalities and within modalities. Supplementary measurements revealed that the efferent activation was spectrally global, as it was for auditory attention. PMID:24732070

  4. Selective attention reduces physiological noise in the external ear canals of humans. II: visual attention.

    PubMed

    Walsh, Kyle P; Pasanen, Edward G; McFadden, Dennis

    2014-06-01

    Human subjects performed in several behavioral conditions requiring, or not requiring, selective attention to visual stimuli. Specifically, the attentional task was to recognize strings of digits that had been presented visually. A nonlinear version of the stimulus-frequency otoacoustic emission (SFOAE), called the nSFOAE, was collected during the visual presentation of the digits. The segment of the physiological response discussed here occurred during brief silent periods immediately following the SFOAE-evoking stimuli. For all subjects tested, the physiological-noise magnitudes were substantially weaker (less noisy) during the tasks requiring the most visual attention. Effect sizes for the differences were >2.0. Our interpretation is that cortico-olivo influences adjusted the magnitude of efferent activation during the SFOAE-evoking stimulation depending upon the attention task in effect, and then that magnitude of efferent activation persisted throughout the silent period where it also modulated the physiological noise present. Because the results were highly similar to those obtained when the behavioral conditions involved auditory attention, similar mechanisms appear to operate both across modalities and within modalities. Supplementary measurements revealed that the efferent activation was spectrally global, as it was for auditory attention.

  5. An immersed boundary method for efficient computational studies of nozzles designed to reduce jet noise

    NASA Astrophysics Data System (ADS)

    Dhamankar, Nitin S.

    Turbulent jet mixing noise has been an active research area for the past 6 decades. Specially designed nozzles that can induce an earlier jet breakdown have shown potential to reduce the far-reaching low-frequency components of jet noise. In the last two decades, large eddy simulation (LES) and computational aeroacoustics (CAA) have become a significant complement to experimental research in quiet nozzle design. High-order finite-difference discretization-based solvers are better suited for CAA applications due to their excellent numerical dissipation and dispersion characteristics. However, geometrical complexities present in many nozzles pose a significant challenge to such solvers, which inherently require structured smooth grids. In the present work, an immersed boundary method (IBM) is implemented in an in-house, highly-scalable, finite-difference discretization-based LES code to tackle this challenge. In IBM, the surface geometry of a body under study is immersed in a non-body-conforming background grid and its effect on the flow is modeled indirectly. The impact of the implemented IBM on the order of accuracy of the base solver is quantified. The method is demonstrated to perform very well in predicting scattering of acoustic waves from a cylinder, and in producing realistic low-Reynolds number viscous flow over a sphere. To simulate experimental-scale high Reynolds number jets at an affordable computational cost, an equilibrium wall model is also implemented in the IBM. It is shown to produce a reasonably accurate outer region for a boundary layer, which is important for jet simulations. The resulting IBM is then applied to analyze the flow-field and noise signature of a round and a chevron nozzle at a subsonic operating condition. The nozzles are based on geometries previously investigated by experimentalists. The lack of experimental flow-field measurements inside the nozzles prevents an agreement of turbulence levels in the initial shear layer of the

  6. Reduced noise susceptibility in littermate offspring from heterozygous animals of the German waltzing guinea pig.

    PubMed

    Skjönsberg, Åsa; Mannström, Paula

    2015-07-08

    The German waltzing guinea pig is a spontaneously mutated strain with severe auditory and vestibular impairment caused by a so far unknown genetic mutation. The animals are born deaf and show a circling behavior. The heterozygote animals of this guinea pig strain have functionally normal hearing and balance. However, these animals have, in earlier studies, shown an increased resistance to noise compared with normal wild-type guinea pigs. In the present study, we explored the functional hearing with auditory brainstem response thresholds before and at different time points after noise exposure. Symptom-free littermates from heterozygote couples of the German waltzing guinea pigs were exclusively used for the study, which, after the hearing test, were sent back for breeding to confirm their genotype (i.e. heterozygote or normal). The aim of this paper was to ascertain that the previously shown reduced susceptibility to noise trauma in the heterozygote animals of the German waltzing guinea pig was also evident when littermates were used as control animals. The findings are important for further analysis of the heterozygote animals of this strain and for future investigations of the underlying mechanisms behind the diverse susceptibility to exposures of loud sound.

  7. Noise-induced coherence and network oscillations in a reduced bursting model.

    PubMed

    Reinker, Stefan; Li, Yue-Xian; Kuske, Rachel

    2006-08-01

    The dynamics of the Hindmarsh-Rose (HR) model of bursting thalamic neurons is reduced to a system of two linear differential equations that retains the subthreshold resonance properties of the HR model. Introducing a reset mechanism after a threshold crossing, we turn this system into a resonant integrate-and-fire (RIF) model. Using Monte-Carlo simulations and mathematical analysis, we examine the effects of noise and the subthreshold dynamic properties of the RIF model on the occurrence of coherence resonance (CR). Synchronized burst firing occurs in a network of such model neurons with excitatory pulse-coupling. The coherence level of the network oscillations shows a stochastic resonance-like dependence on the noise level. Stochastic analysis of the equations shows that the slow recovery from the spike-induced inhibition is crucial in determining the frequencies of the CR and the subthreshold resonance in the original HR model. In this particular type of CR, the oscillation frequency strongly depends on the intrinsic time scales but changes little with the noise intensity. We give analytical quantities to describe this CR mechanism and illustrate its influence on the emerging network oscillations. We discuss the profound physiological roles this kind of CR may have in information processing in neurons possessing a subthreshold resonant frequency and in generating synchronized network oscillations with a frequency that is determined by intrinsic properties of the neurons.

  8. Roughness distribution of multiple hit and long surface diffusion length noise reduced discrete growth models

    NASA Astrophysics Data System (ADS)

    Disrattakit, P.; Chanphana, R.; Chatraphorn, P.

    2016-11-01

    Conventionally, the universality class of a discrete growth model is identified via the scaling of interface width. This method requires large-scale simulations to minimize finite-size effects on the results. The multiple hit noise reduction techniques (m > 1 NRT) and the long surface diffusion length noise reduction techniques (ℓ > 1 NRT) have been used to promote the asymptotic behaviors of the growth models. Lately, an alternative method involving comparison of roughness distribution in the steady state has been proposed. In this work, the roughness distribution of the (2 +1)-dimensional Das Sarma-Tamborenea (DT), Wolf-Villain (WV), and Larger Curvature (LC) models, with and without NRTs, are calculated in order to investigate effects of the NRTs on the roughness distribution. Additionally, effective growth exponents of the noise reduced (2 +1)-dimensional DT, WV and LC models are also calculated. Our results indicate that the NRTs affect the interface width both in the growth and the saturation regimes. In the steady state, the NRTs do not seem to have any impact on the roughness distribution of the DT model, but it significantly changes the roughness distribution of the WV and LC models to the normal distribution curves.

  9. Configuration of three distributed lines for reducing noise due to the coupling of the common and normal modes

    NASA Astrophysics Data System (ADS)

    Jinno, Souma; Toki, Hiroshi; Abe, Masayoshi

    2017-02-01

    In this study, the coupling between the common and normal modes in distributed lines and the resulting electromagnetic noise were considered. The telegraph equations of three distributed lines with the boundary conditions of a lumped circuit reveal the presence of mode-coupling noise. To reduce the coupling noise, the geometrically and electrically symmetric configuration of the three distributed lines is proposed. The simulation results show that the proposed configuration can decrease the mode-coupling noise by a factor of 1 ×10-8 in comparison with that of asymmetric configurations.

  10. Algorithms and analyses for stochastic optimization for turbofan noise reduction using parallel reduced-order modeling

    NASA Astrophysics Data System (ADS)

    Yang, Huanhuan; Gunzburger, Max

    2017-06-01

    Simulation-based optimization of acoustic liner design in a turbofan engine nacelle for noise reduction purposes can dramatically reduce the cost and time needed for experimental designs. Because uncertainties are inevitable in the design process, a stochastic optimization algorithm is posed based on the conditional value-at-risk measure so that an ideal acoustic liner impedance is determined that is robust in the presence of uncertainties. A parallel reduced-order modeling framework is developed that dramatically improves the computational efficiency of the stochastic optimization solver for a realistic nacelle geometry. The reduced stochastic optimization solver takes less than 500 seconds to execute. In addition, well-posedness and finite element error analyses of the state system and optimization problem are provided.

  11. New noise reduction method for reducing CT scan dose: Combining Wiener filtering and edge detection algorithm

    NASA Astrophysics Data System (ADS)

    Anam, Choirul; Haryanto, Freddy; Widita, Rena; Arif, Idam

    2015-09-01

    New noise reduction method for reducing dose of CT scans has been proposed. The new method is expected to address the major problems in the noise reduction algorithm, i.e. the decreasing in the spatial resolution of the image. The proposed method was developed by combining adaptive Wiener filtering and edge detection algorithms. The first step, the image was filtered with a Wiener filter. Separately, edge detection operation performed on the original image using the Prewitt method. The next step, a new image was generated based on the edge detection operation. At the edge area, the image was taken from the original image, while at the non-edge area, the image was taken from the image that had been filtered with a Wiener filter. The new method was tested on a CT image of the spatial resolution phantom, which was scanned by different current-time multiplication, namely 80, 130 and 200 mAs, while other exposure factors were kept in constant conditions. The spatial resolution phantom consists of six sets of bar pattern made of plexi-glass and separated at some distance by water. The new image quality assessed from the amount of noise and the magnitude of spatial resolution. Noise was calculated by determining the standard deviation of the homogeneous regions, while the spatial resolution was assessed by observation of the area sets of the bar pattern. In addition, to evaluate the performance of this new method has also been tested on patient CT images. From the measurements, the new method can reduce the noise to an average 64.85%, with a spatial resolution does not decrease significantly. Visually, the third set bar on the image phantom (the distance between the bar 1.0 mm) can still be distinguished, as well as on the original image. Meanwhile, if the image is only processed using Wiener filter, the second set bar (the distance between the bar 1.3 mm) are distinguishable. Testing this new method to patient image, its results in relatively the same. Thus, using this

  12. Hearing thresholds, threshold repeatability, and attenuation values for passive noise-reducing earphone enclosures.

    PubMed

    Frank, T; Greer, A C; Magistro, D M

    1997-11-01

    Passive noise-reducing earphone enclosures contain a supra-aural earphone mounted in a plastic dome. These enclosures are used to prevent the elevation of hearing thresholds due to masking from high levels of ambient noise. This research determined normal hearing threshold levels, threshold repeatability, and attenuation values for an Audiocup, Auraldome II, AudioMate, and Madsen ME-70 enclosure. In Study I hearing thresholds were obtained for 30 normally hearing adults from 500 to 6000 Hz in four test sessions for each enclosure and a supra-aural earphone attached to a headband. The hearing thresholds and repeatability for the Audiocup and Auraldome were similar but the thresholds were higher and repeatability was poorer for the AudioMate and Madsen ME-70 compared with the supra-aural earphone. In Study II real-ear attenuation values were obtained for each enclosure using 24 normally hearing subjects. The Audiocup and Auraldome II provided less low-frequency attenuation compared with the AudioMate and Madsen ME-70. The findings were related to the coupling of the supra-aural earphone in each enclosure to the ear and the coupling of each enclosure to the head. If an enclosure is used as an alternative to a supra-aural earphone for hearing testing in high ambient noise environments, hearing thresholds and threshold repeatability should be similar to a supra-aural earphone, and the enclosures should provide adequate attenuation of ambient noise. Since none of the enclosures met all of these requirements their use is not recommended for hearing testing.

  13. Improving patients' sleep: reducing light and noise levels on wards at night.

    PubMed

    Hewart, Carol; Fethney, Loveday

    2016-02-01

    There is much research concerning the psychological and physical effects of sleep deprivation on patients in healthcare systems, yet interrupted sleep on hospital wards at night remains a problem. Staff at Plymouth Hospitals NHS Trust, Devon, wanted to identify the factors that prevent patients from sleeping well at night. Two audits were carried out, between April and August 2015, to assess noise and light levels on wards at night, and to engage nurses in ways of reducing these. A number of recommendations were made based on the audit findings, many of which have been put into practice.

  14. Background noise measurements from jet exit vanes designed to reduced flow pulsations in an open-jet wind tunnel

    NASA Technical Reports Server (NTRS)

    Hoad, D. R.; Martin, R. M.

    1985-01-01

    Many open jet wind tunnels experience pulsations of the flow which are typically characterized by periodic low frequency velocity and pressure variations. One method of reducing these fluctuations is to install vanes around the perimeter of the jet exit to protrude into the flow. Although these vanes were shown to be effective in reducing the fluctuation content, they can also increase the test section background noise level. The results of an experimental acoustic program in the Langley 4- by 7-Meter Tunnel is presented which evaluates the effect on tunnel background noise of such modifications to the jet exit nozzle. Noise levels for the baseline tunnel configuration are compared with those for three jet exit nozzle modifications, including an enhanced noise reduction configuration that minimizes the effect of the vanes on the background noise. Although the noise levels for this modified vane configuration were comparable to baseline tunnel background noise levels in this facility, installation of these modified vanes in an acoustic tunnel may be of concern because the noise levels for the vanes could be well above background noise levels in a quiet facility.

  15. Grape marc reduces methane emissions when fed to dairy cows.

    PubMed

    Moate, P J; Williams, S R O; Torok, V A; Hannah, M C; Ribaux, B E; Tavendale, M H; Eckard, R J; Jacobs, J L; Auldist, M J; Wales, W J

    2014-01-01

    Grape marc (the skins, seeds, stalk, and stems remaining after grapes have been pressed to make wine) is currently a by-product used as a feed supplement by the dairy and beef industries. Grape marc contains condensed tannins and has high concentrations of crude fat; both these substances can reduce enteric methane (CH4) production when fed to ruminants. This experiment examined the effects of dietary supplementation with either dried, pelleted grape marc or ensiled grape marc on yield and composition of milk, enteric CH4 emissions, and ruminal microbiota in dairy cows. Thirty-two Holstein dairy cows in late lactation were offered 1 of 3 diets: a control (CON) diet; a diet containing dried, pelleted grape marc (DGM); and a diet containing ensiled grape marc (EGM). The diet offered to cows in the CON group contained 14.0kg of alfalfa hay dry matter (DM)/d and 4.3kg of concentrate mix DM/d. Diets offered to cows in the DGM and EGM groups contained 9.0kg of alfalfa hay DM/d, 4.3kg of concentrate mix DM/d, and 5.0kg of dried or ensiled grape marc DM/d, respectively. These diets were offered individually to cows for 18d. Individual cow feed intake and milk yield were measured daily and milk composition measured on 4d/wk. Individual cow CH4 emissions were measured by the SF6 tracer technique on 2d at the end of the experiment. Ruminal bacterial, archaeal, fungal, and protozoan communities were quantified on the last day of the experiment. Cows offered the CON, DGM, and EGM diets, ate 95, 98, and 96%, respectively, of the DM offered. The mean milk yield of cows fed the EGM diet was 12.8kg/cow per day and was less than that of cows fed either the CON diet (14.6kg/cow per day) or the DGM diet (15.4kg/cow per day). Feeding DGM and EGM diets was associated with decreased milk fat yields, lower concentrations of saturated fatty acids, and enhanced concentrations of mono- and polyunsaturated fatty acids, in particular cis-9,trans-11 linoleic acid. The mean CH4 emissions were

  16. Gas reception uses modern solvents to reduce emissions

    SciTech Connect

    Pelekanou, A.; Vaughan, C.M.

    1996-12-31

    The Point of Ayr Terminal is the first gas plant to be built in Wales. It processes Natural Gas from BHP`s Liverpool Bay Development to feed a new 1,050 mega watt gas fired power station located at Connahs Quay, situated about 27 km south of the Terminal. This paper describes the overall process and focuses in particular on a relatively new process which uses one of a novel range of amines for treatment of natural gases containing both H{sub 2}S and mercaptans. The gas terminal is the first in the United Kingdom to include a Claus Tail Gas Unit to enhance sulfur recovery and achieve the latest HM Inspectorate of Pollution (HMIP) guidelines for recovery, therefore reducing the terminal sulfur dioxide emissions. The authorization includes targets for sulfur recovery at 99.95% and requires the use of low NOx burners for all fired equipment. Strict limits on the water quality are set and water discharged to the watercourse must be of river quality, and require checking prior to discharge.

  17. Forest management strategies for reducing carbon emissions, the French case

    NASA Astrophysics Data System (ADS)

    Valade, Aude; Luyssaert, Sebastiaan; Bellassen, Valentin; Vallet, Patrick; Martin, Manuel

    2015-04-01

    International agreements now recognize the role of forest in the mitigation of climate change through the levers of in-situ sequestration, storage in products and energy and product substitution. These three strategies of carbon management are often antagonistic and it is still not clear which strategy would have the most significant impact on atmospheric carbon concentrations. With a focus on France, this study compares several scenarios of forest management in terms of their effect on the overall carbon budget from trees to wood-products. We elaborated four scenarios of forest management that target different wood production objectives. One scenario is 'Business as usual' and reproduces the current forest management and wood production levels. Two scenarios target an increase in bioenergy wood production, with either long-term or short-term goals. One scenario aims at increasing the production of timber for construction. For this, an empirical regression model was developed building on the rich French inventory database. The model can project the current forest resource at a time horizon of 20 years for characteristic variables diameter, standing volume, above-ground biomass, stand age. A simplified life-cycle analysis provides a full carbon budget for each scenario from forest management to wood use and allows the identification of the scenario that most reduces carbon emissions.

  18. 77 FR 18297 - Air Traffic Noise, Fuel Burn, and Emissions Modeling Using the Aviation Environmental Design Tool...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-27

    ... Environmental Design Tool Version 2a AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Policy... Aviation Environmental Design Tool version 2a (AEDT 2a) to analyze noise, fuel burn, and emissions for FAA... of an airport, incorporates more than one airport, or includes actions above 3,000 feet above...

  19. Pre-processing variance reducing techniques in multispectral positron emission tomography.

    PubMed

    Yao, R; Msaki, P; Lecomte, R

    1997-11-01

    Stochastic fluctuations and systematic errors severely restrict the potential of multispectral acquisition to improve scatter correction by energy-dependent processing in high-resolution positron emission tomography (PET). To overcome this limitation, three pre-processing approaches which reduce stochastic fluctuations and systematic errors without degrading spatial resolution were investigated: statistical variance was reduced by smoothing acquired data in energy space, systematic errors due to nonuniform detector efficiency were minimized by normalizing the data in the spatial domain and the overall variance was further reduced by selecting an optimal pre-processing sequence. Selection of the best protocol to reduce stochastic fluctuations entailed comparisons between four smoothing algorithms (prior constrained (PC) smoothing, weighted smoothing (WS), ideal low-pass filtering (ILF) and mean median (MM) smoothing) and permutations of three pre-processing procedures (smoothing, normalization and subtraction of random events). Results demonstrated that spectral smoothing by WS, ILF and MM efficiently reduces the statistical variance in both the energy and spatial domains without observable spatial resolution loss. The ILF algorithm was found to be the most convenient in terms of simplicity and efficiency. Regardless of the position of subtraction of randoms in the sequence, reduction of the systematic errors by normalization followed by spectral smoothing to suppress statistical noise produced the best results. However, subtraction of random events first in the sequence reduces computation load by half since the need to pre-process this distribution before subtraction is removed. In summary, normalizing data in the spatial domain and smoothing data in energy space are essential steps required to reduce systematic errors and statistical variance independently without degrading spatial resolution of multispectral PET data.

  20. Reduced effects of pictorial distinctiveness on false memory following dynamic visual noise.

    PubMed

    Parker, Andrew; Kember, Timothy; Dagnall, Neil

    2017-07-01

    High levels of false recognition for non-presented items typically occur following exposure to lists of associated words. These false recognition effects can be reduced by making the studied items more distinctive by the presentation of pictures during encoding. One explanation of this is that during recognition, participants expect or attempt to retrieve distinctive pictorial information in order to evaluate the study status of the test item. If this involves the retrieval and use of visual imagery, then interfering with imagery processing should reduce the effectiveness of pictorial information in false memory reduction. In the current experiment, visual-imagery processing was disrupted at retrieval by the use of dynamic visual noise (DVN). It was found that effects of DVN dissociated true from false memory. Memory for studied words was not influenced by the presence of an interfering noise field. However, false memory was increased and the effects of picture-induced distinctiveness was eliminated. DVN also increased false recollection and remember responses to unstudied items.

  1. Viscoelastic property tuning for reducing noise radiated by switched-reluctance machines

    NASA Astrophysics Data System (ADS)

    Millithaler, Pierre; Dupont, Jean-Baptiste; Ouisse, Morvan; Sadoulet-Reboul, Émeline; Bouhaddi, Noureddine

    2017-10-01

    Switched-reluctance motors (SRM) present major acoustic drawbacks that hinder their use for electric vehicles in spite of widely-acknowledged robustness and low manufacturing costs. Unlike other types of electric machines, a SRM stator is completely encapsulated/potted with a viscoelastic resin. By taking advantage of the high damping capacity that a viscoelastic material has in certain temperature and frequency ranges, this article proposes a tuning methodology for reducing the noise emitted by a SRM in operation. After introducing the aspects the tuning process will focus on, the article details a concrete application consisting in computing representative electromagnetic excitations and then the structural response of the stator including equivalent radiated power levels. An optimised viscoelastic material is determined, with which the peak radiated levels are reduced up to 10 dB in comparison to the initial state. This methodology is implementable for concrete industrial applications as it only relies on common commercial finite-element solvers.

  2. Management Options for Reducing Ammonia Emissions from Poultry Litter

    USDA-ARS?s Scientific Manuscript database

    Ammonia emissions from poultry litter not only result in air pollution; high levels of ammonia in poultry houses cause poor bird performance, increase the susceptibility of birds to viral diseases, and negatively impact human health. Although ammonia emissions are a concern, few cost-effective best ...

  3. Feed management for beef feedlots to reduce air emissions

    USDA-ARS?s Scientific Manuscript database

    This power point presentation gives an overview of air emissions from beef cattle feedyards as well as nutritional and management techniques that might decrease these emissions. Topics include greenhouse gases (methane, nitrous oxide), ammonia, particulate matter and odors. This was presented as on...

  4. Prospects for residential oil burners with reduced emissions

    SciTech Connect

    Butcher, T.A.; Krajewski, R.F.; Celebi, Y.; McDonald, R.J. ); Batey, J. )

    1992-04-01

    In considering the emissions characteristics of residential oil heating equipment it is important to consider the magnitude of these emissions relative to all other sources. Laboratory and field test data show that home oil burners produce very low levels of pollutants when compared to all other combustion sources in the US. Home oil burners are relatively clean burning and produce less air pollution than the average combustion source in the US. This is especially true for carbon monoxide, particulates, and hydrocarbons, which are a small fraction of the average emission of other combustion equipment. In this paper results are presented of emission tests done with a number of oil burners selected as being representative of modern equipment or representing a recent development trend or a novel approach. The primary purpose of this work was to provide a benchmark of what oil equipment can do today and what the effects of some of these alternative designs are on emissions.

  5. Core-Noise

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2010-01-01

    This presentation is a technical progress report and near-term outlook for NASA-internal and NASA-sponsored external work on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system level noise metrics for the 2015, 2020, and 2025 timeframes; the emerging importance of core noise and its relevance to the SFW Reduced-Noise-Aircraft Technical Challenge; the current research activities in the core-noise area, with some additional details given about the development of a high-fidelity combustion-noise prediction capability; the need for a core-noise diagnostic capability to generate benchmark data for validation of both high-fidelity work and improved models, as well as testing of future noise-reduction technologies; relevant existing core-noise tests using real engines and auxiliary power units; and examples of possible scenarios for a future diagnostic facility. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Noise-Aircraft Technical Challenge aims to enable concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical for enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor designs could increase

  6. Reduced acoustic noise in diffusion tensor imaging on a compact MRI system.

    PubMed

    Tan, Ek T; Hardy, Christopher J; Shu, Yunhong; In, Myung-Ho; Guidon, Arnaud; Huston, John; Bernstein, Matt A; K F Foo, Thomas

    2017-10-02

    To investigate the feasibility of substantially reducing acoustic noise while performing diffusion tensor imaging (DTI) on a compact 3T (C3T) MRI scanner equipped with a 42-cm inner-diameter asymmetric gradient. A-weighted acoustic measurements were made using 10 mT/m-amplitude sinusoidal waveforms, corresponding to echo-planar imaging (EPI) echo spacing of 0.25 to 5.0 ms, on a conventional, whole-body 3T MRI and on the C3T. Acoustic measurements of DTI with trapezoidal EPI waveforms were then made at peak gradient performance on the C3T (80 mT/m amplitude, 700 T/m/s slew rate) and at derated performance (33 mT/m, 10 to 50 T/m/s) for acoustic noise reduction. DTI was acquired in two different phantoms and in seven human subjects, with and without gradient-derating corresponding to multi- and single-shot acquisitions, respectively. Sinusoidal waveforms on the C3T were quieter by 8.5 to 15.6 A-weighted decibels (dBA) on average as compared to the whole-body MRI. The derated multishot DTI acquisition noise level was only 8.7 dBA (at 13 T/m/s slew rate) above ambient, and was quieter than non-derated, single-shot DTI by 22.3 dBA; however, the scan time was almost quadrupled. Although derating resulted in negligible diffusivity differences in the phantoms, small biases in diffusivity measurements were observed in human subjects (apparent diffusion coefficient = +9.3 ± 8.8%, fractional anisotropy = +3.2 ± 11.2%, radial diffusivity = +9.4 ± 16.8%, parallel diffusivity = +10.3 ± 8.4%). The feasibility of achieving reduced acoustic noise levels with whole-brain DTI on the C3T MRI was demonstrated. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  7. Core Noise - Increasing Importance

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2011-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015, 2020, and 2025 timeframes; turbofan design trends and their aeroacoustic implications; the emerging importance of core noise and its relevance to the SFW Reduced-Perceived-Noise Technical Challenge; and the current research activities in the core-noise area, with additional details given about the development of a high-fidelity combustor-noise prediction capability as well as activities supporting the development of improved reduced-order, physics-based models for combustor-noise prediction. The need for benchmark data for validation of high-fidelity and modeling work and the value of a potential future diagnostic facility for testing of core-noise-reduction concepts are indicated. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor

  8. Improvement of material decomposition and image quality in dual-energy radiography by reducing image noise

    NASA Astrophysics Data System (ADS)

    Lee, D.; Kim, Y.-s.; Choi, S.; Lee, H.; Choi, S.; Jo, B. D.; Jeon, P.-H.; Kim, H.; Kim, D.; Kim, H.; Kim, H.-J.

    2016-08-01

    Although digital radiography has been widely used for screening human anatomical structures in clinical situations, it has several limitations due to anatomical overlapping. To resolve this problem, dual-energy imaging techniques, which provide a method for decomposing overlying anatomical structures, have been suggested as alternative imaging techniques. Previous studies have reported several dual-energy techniques, each resulting in different image qualities. In this study, we compared three dual-energy techniques: simple log subtraction (SLS), simple smoothing of a high-energy image (SSH), and anti-correlated noise reduction (ACNR) with respect to material thickness quantification and image quality. To evaluate dual-energy radiography, we conducted Monte Carlo simulation and experimental phantom studies. The Geant 4 Application for Tomographic Emission (GATE) v 6.0 and tungsten anode spectral model using interpolation polynomials (TASMIP) codes were used for simulation studies and digital radiography, and human chest phantoms were used for experimental studies. The results of the simulation study showed improved image contrast-to-noise ratio (CNR) and coefficient of variation (COV) values and bone thickness estimation accuracy by applying the ACNR and SSH methods. Furthermore, the chest phantom images showed better image quality with the SSH and ACNR methods compared to the SLS method. In particular, the bone texture characteristics were well-described by applying the SSH and ACNR methods. In conclusion, the SSH and ACNR methods improved the accuracy of material quantification and image quality in dual-energy radiography compared to SLS. Our results can contribute to better diagnostic capabilities of dual-energy images and accurate material quantification in various clinical situations.

  9. Noise Gating Solar Images

    NASA Astrophysics Data System (ADS)

    DeForest, Craig; Seaton, Daniel B.; Darnell, John A.

    2017-08-01

    I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO

  10. Thermochemical conversion of biomass storage covers to reduce ammonia emissions from dairy manure Thermochemical conversion of biomass storage covers to reduce ammonia emissions from dairy manure

    USDA-ARS?s Scientific Manuscript database

    Manure storages, and in particular those storing digested manure, are a source of ammonia (NH3) emissions. Permeable manure storage covers can reduce NH3 emissions, however performance can decline as they degrade. Thermochemical conversion of biomass through pyrolysis and steam treatment could incre...

  11. Comparing changes in transient-evoked otoacoustic emission and pure-tone audiometry following short exposure to industrial noise.

    PubMed

    Slliwinska-Kowalska, Mariola; Kotylo, Piotr; Hendler, Beata

    1999-01-01

    It has been suggested that otoacoustic emissions, particularly transient-evoked otoacoustic emissions (TEOAE), might be more sensitive in assessment of changes to the cochlea caused by noise than pure-tone audiometry (PTA). The aim of the study was to compare temporary threshold shifts with the changes in TEOAE following a six-hour exposure to industrial noise at the intensity of 85-97 dB (A). Thirty two male employees of a metal factory were screened. TEOAE, PTA and tympanometry were included in the hearing test battery. Both, PTA and TEOAE showed significant reduction due to noise exposure, but no correlation between temporary threshold shifts and decreases in either the overall TOAE level or the level of otoacoustic emission in the frequency bands was found. Our results confirm the high sensitivity of TEOAE to short exposure to industrial noise. This study may recommend this measurement as a method of evaluation for TTS conditions for hearing conservation programme purposes, in addition to pure-tone audiometry.

  12. Northwest Ports Achievements in Reducing Emissions and Improving Performance

    EPA Pesticide Factsheets

    Case history on the status of the Northwest Ports Clean Air Strategy for the Port of Seattle, Port of Tacoma, and Port Metro Vancouver. Presents key objectives, emission and performance goals and outcomes.

  13. Development of an air bubble curtain to reduce underwater noise of percussive piling.

    PubMed

    Würsig, B; Greene, C R; Jefferson, T A

    2000-02-01

    Underwater bubbles can inhibit sound transmission through water due to density mismatch and concomitant reflection and absorption of sound waves. For the present study, a perforated rubber hose was used to produce a bubble curtain, or screen, around pile-driving activity in 6-8-m depth waters of western Hong Kong. The percussive hammer blow sounds of the pile driver were measured on 2 days at distances of 250, 500, and 1000 m; broadband pulse levels were reduced by 3-5 dB by the bubble curtain. Sound intensities were measured from 100 Hz to 25.6 kHz, and greatest sound reduction by the bubble curtain was evident from 400 to 6400 Hz. Indo-Pacific hump-backed dolphins (Sousa chinensis) occurred in the immediate area of the industrial activity before and during pile driving, but with a lower abundance immediately after it. While hump-backed dolphins generally showed no overt behavioral changes with and without pile driving, their speeds of travel increased during pile driving, indicating that bubble screening did not eliminate all behavioral responses to the loud noise. Because the bubble curtain effectively lowered sound levels within 1 km of the activity, the experiment and its application during construction represented a success, and this measure should be considered for other appropriate areas with high industrial noises and resident or migrating sound-sensitive animals.

  14. Reduced Noise UV Enhancement of Etch Rates for Nuclear Tracks in CR-39

    NASA Astrophysics Data System (ADS)

    Sheets, Rebecca; Clarkson, David; Ume, Rubab; Regan, Sean; Sangster, Craig; Padalino, Stephen; McLean, James

    2016-10-01

    The use of CR-39 plastic as a Solid State Nuclear Track Detector is an effective technique for obtaining data in high-energy particle experiments including inertial confinement fusion. To reveal particle tracks after irradiation, CR-39 is chemically etched in NaOH at 80°C for 6 hours, producing micron-scale signal pits at the nuclear track sites. Using CR-39 irradiated with 5.4 MeV alpha particles and 1.0 MeV protons, we show that exposing the CR-39 to high intensity UV light before etching, with wavelengths between 240 nm and 350 nm, speeds the etch process. Elevated temperatures during UV exposure amplifies this effect, with etch rates up to 50% greater than unprocessed conditions. CR-39 pieces exposed to UV light and heat can also exhibit heightened levels of etch-induced noise (surface features not caused by nuclear particles). By illuminating the CR-39 from the side opposite to the tracks, a similar level of etch enhancement was obtained with little to no noise. The effective wavelength range is reduced, due to strong attenuation of shorter wavelengths. Funded in part by a LLE contract through the DOE.

  15. A reduced-scale railway noise barrier's insertion loss and absorption coefficients: comparison of field measurements and predictions

    NASA Astrophysics Data System (ADS)

    Busch, T. A.; Nugent, R. E.

    2003-10-01

    In situ testing determined the insertion loss ( IL) and absorption coefficients of a candidate absorptive noise barrier (soundwall) to abate railway noise for residents of Anaheim, CA. A 4000 m barrier is proposed south of the tracks, but residential areas to the north have expressed concerns that barrier reflections will increase their noise exposure. To address these concerns, a 3.66 m high by 14.6 m long demonstration barrier was built in the parking lot of Edison Field, Anaheim, as part of a public open house, thereby allowing for acoustical measurements. Insertion loss ( IL) was measured in third-octave bands assuming 1/2-scale construction. The IL for three, scaled railway noise sub-sources (rail/wheel interface, locomotive, and train horn) was measured at six, scaled distances. The highest total, A-weighted IL, after corrections for finite-barrier and point-source speaker effects was 22 dB(A) for rail/wheel noise, 18 dB(A) for locomotive noise, and 20 dB(A) for train horn noise. These results can be compared favourably to IL predictions made using algorithms from the US Federal Rail Administration (FRA) noise assessment guidelines. For the actual barrier installation, shielded residential receivers located south of the project are expected to see their future noise exposures reduced from an unmitigated 78 CNEL to 65 CNEL. Absorption coefficients were measured using time delay spectrometry. At lower frequencies, measured absorption coefficients were notably less than the reverberation room results advertised in the manufacturer's literature, but generally conformed with impedance tube results. At higher frequencies the correspondence between measured absorption coefficients and reverberation room results was much improved. For the actual barrier installation, unshielded residential receivers to the north are expected to experience noise exposure increases of less than 1 dB(A). This factor of increase is consistent with a finding of no impact when assessed

  16. Aspects of reducing spur gear noise. [design criteria for gear teeth

    NASA Technical Reports Server (NTRS)

    Giurgiuman, H.; Cretu, M.; Moraru, I.

    1974-01-01

    Noise sources in gears and ways of improving their silence by profile shape alterations and wheel surface smoothness are discussed. Practical results obtained, from the noise point of view are reported, for textile machinery.

  17. Removal of floral microbiota reduces floral terpene emissions

    NASA Astrophysics Data System (ADS)

    Peñuelas, Josep; Farré-Armengol, Gerard; Llusia, Joan; Gargallo-Garriga, Albert; Rico, Laura; Sardans, Jordi; Terradas, Jaume; Filella, Iolanda

    2014-10-01

    The emission of floral terpenes plays a key role in pollination in many plant species. We hypothesized that the floral phyllospheric microbiota could significantly influence these floral terpene emissions because microorganisms also produce and emit terpenes. We tested this hypothesis by analyzing the effect of removing the microbiota from flowers. We fumigated Sambucus nigra L. plants, including their flowers, with a combination of three broad-spectrum antibiotics and measured the floral emissions and tissular concentrations in both antibiotic-fumigated and non-fumigated plants. Floral terpene emissions decreased by ca. two thirds after fumigation. The concentration of terpenes in floral tissues did not decrease, and floral respiration rates did not change, indicating an absence of damage to the floral tissues. The suppression of the phyllospheric microbial communities also changed the composition and proportion of terpenes in the volatile blend. One week after fumigation, the flowers were not emitting β-ocimene, linalool, epoxylinalool, and linalool oxide. These results show a key role of the floral phyllospheric microbiota in the quantity and quality of floral terpene emissions and therefore a possible key role in pollination.

  18. Removal of floral microbiota reduces floral terpene emissions

    PubMed Central

    Peñuelas, Josep; Farré-Armengol, Gerard; Llusia, Joan; Gargallo-Garriga, Albert; Rico, Laura; Sardans, Jordi; Terradas, Jaume; Filella, Iolanda

    2014-01-01

    The emission of floral terpenes plays a key role in pollination in many plant species. We hypothesized that the floral phyllospheric microbiota could significantly influence these floral terpene emissions because microorganisms also produce and emit terpenes. We tested this hypothesis by analyzing the effect of removing the microbiota from flowers. We fumigated Sambucus nigra L. plants, including their flowers, with a combination of three broad-spectrum antibiotics and measured the floral emissions and tissular concentrations in both antibiotic-fumigated and non-fumigated plants. Floral terpene emissions decreased by ca. two thirds after fumigation. The concentration of terpenes in floral tissues did not decrease, and floral respiration rates did not change, indicating an absence of damage to the floral tissues. The suppression of the phyllospheric microbial communities also changed the composition and proportion of terpenes in the volatile blend. One week after fumigation, the flowers were not emitting β-ocimene, linalool, epoxylinalool, and linalool oxide. These results show a key role of the floral phyllospheric microbiota in the quantity and quality of floral terpene emissions and therefore a possible key role in pollination. PMID:25335793

  19. Reducing Patient Radiation Dose With Image Noise Reduction Technology in Transcatheter Aortic Valve Procedures.

    PubMed

    Lauterbach, Michael; Hauptmann, Karl Eugen

    2016-03-01

    X-ray radiation exposure is of great concern for patients undergoing structural heart interventions. In addition, a larger group of medical staff is required and exposed to radiation compared with percutaneous coronary interventions. This study aimed at quantifying radiation dose reduction with implementation of specific image noise reduction technology (NRT) in transcatheter aortic valve implantation (TAVI) procedures. We retrospectively analyzed 104 consecutive patients with TAVI procedures, 52 patients before and 52 after optimization of x-ray radiation chain, and implementation of NRT. Patients with 1-step TAVI and complex coronary intervention, or complex TAVI procedures, were excluded. Before the procedure, all patients received a multislice computed tomography scan, which was used to size aortic annulus, select the optimal implantation plane, valve type and size, and guide valve implantation using a software tool. Air kerma and kerma-area product were compared in both groups to determine patient radiation dose reduction. Baseline parameters, co-morbidity, or procedural data were comparable between groups. Mean kerma-area product was significantly lower (p <0.001) in the NRT group compared with the standard group (60 ± 39 vs 203 ± 106 Gy × cm(2), p <0.001), which corresponds to a reduction of 70%. Mean air kerma was reduced by 64% (494 ± 360 vs 1,355 ± 657 mGy, p <0.001). In conclusion, using optimized x-ray chain combined with specific image noise reduction technology has the potential to significantly reduce by 2/3 radiation dose in standard TAVI procedures without worsening image quality or prolonging procedure time. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Airborne reduced nitrogen: ammonia emissions from agriculture and other sources.

    PubMed

    Anderson, Natalie; Strader, Ross; Davidson, Cliff

    2003-06-01

    Ammonia is a basic gas and one of the most abundant nitrogen-containing compounds in the atmosphere. When emitted, ammonia reacts with oxides of nitrogen and sulfur to form particles, typically in the fine particle size range. Roughly half of the PM(2.5) mass in eastern United States is ammonium sulfate, according to the US EPA. Results from recent studies of PM(2.5) show that these fine particles are typically deposited deep in the lungs and may lead to increased morbidity and/or mortality. Also, these particles are in the size range that will degrade visibility. Ammonia emission inventories are usually constructed by multiplying an activity level by an experimentally determined emission factor for each source category. Typical sources of ammonia include livestock, fertilizer, soils, forest fires and slash burning, industry, vehicles, the oceans, humans, pets, wild animals, and waste disposal and recycling activities. Livestock is the largest source category in the United States, with waste from livestock responsible for about 3x10(9) kg of ammonia in 1995. Volatilization of ammonia from livestock waste is dependent on many parameters, and thus emission factors are difficult to predict. Despite a seasonal variation in these values, the emission factors for general livestock categories are usually annually averaged in current inventories. Activity levels for livestock are from the USDA Census of Agriculture, which does not give information about animal raising practices such as housing types and grazing times, waste handling systems, and approximate animal slurry spreading times or methods. Ammonia emissions in the United States in 1995 from sources other than livestock are much lower; for example, annual emissions are roughly 8x10(8) kg from fertilizer, 7x10(7) kg from industry, 5x10(7) kg from vehicles and 1x10(8) kg from humans. There is considerable uncertainty in the emissions from soil and vegetation, although this category may also be significant

  1. Emerging Community Noise Reduction Approaches

    NASA Technical Reports Server (NTRS)

    Envia, Edmane

    2012-01-01

    An overview of the current NASA research portfolio in the area of aircraft noise reduction is presented. The emphasis of the research described herein is on meeting the aggressive near- and mid-term national goals for reducing aircraft noise emissions, which NASA internal studies have shown to be feasible using noise reduction technologies currently being developed in-house or in partnership with NASA s industry and academic partners. While NASA has an active research effort in airframe noise reduction, this overview focuses on propulsion noise reduction only.

  2. Effects of reversible noise exposure on the suppression tuning of rabbit distortion-product otoacoustic emissions

    NASA Astrophysics Data System (ADS)

    Howard, Mackenzie A.; Stagner, Barden B.; Lonsbury-Martin, Brenda L.; Martin, Glen K.

    2002-01-01

    Distortion-product otoacoustic emissions (DPOAEs) at 2f1-f2 can be suppressed by the introduction of a third ``suppressor'' tone. Plotting the suppression of the DPOAE level against the changing frequency and level of the suppressor produces frequency-tuning functions referred to as suppression tuning curves (STCs). The dominant features of STCs, including their shape, are similar to the features of neural tuning curves (NTCs) recorded from single auditory nerve fibers. However, recent findings using reversible diuretics suggest that STCs do not provide the same measure of cochlear frequency selectivity as provided by NTCs. To determine if STCs are also insensitive to the adverse effects of excessive sounds, the present study exposed rabbits to a moderate-level noise that produced temporary threshold shift-like (TTS) effects on DPOAEs, and examined the influence of such exposures on STCs. DPOAEs were produced using primary tones with geometric-mean frequencies centered at 2.8 or 4 kHz, and with L1 and L2 values of 45/45, 50/35, 50/50, and 55/45 dB SPL. STCs were obtained before and during recovery for a period of approximately 2 h immediately following, and at 1, 2, 3, and 7 d post-exposure to a 2 kHz octave band noise, at levels and durations sufficient to cause significant but reversible reductions in DPOAE levels. STC data included tip center frequency, tip threshold, and Q10dB measures of tuning for suppression criteria of 3, 6, 9, and 12 dB. Recovery was variable between animals, but all rabbits recovered fully by 7 d post-exposure. STC center frequencies measured during the TTS typically tuned to a slightly higher frequency, while tip thresholds tended to decrease and Q10dB increase. Together, the results indicate that, despite similarities in the general properties of STCs and NTCs, these two types of tuning curves are affected differently following reversible cochlear insult.

  3. Realistic simulation of reduced-dose CT with noise modeling and sinogram synthesis using DICOM CT images

    SciTech Connect

    Won Kim, Chang; Kim, Jong Hyo

    2014-01-15

    Purpose: Reducing the patient dose while maintaining the diagnostic image quality during CT exams is the subject of a growing number of studies, in which simulations of reduced-dose CT with patient data have been used as an effective technique when exploring the potential of various dose reduction techniques. Difficulties in accessing raw sinogram data, however, have restricted the use of this technique to a limited number of institutions. Here, we present a novel reduced-dose CT simulation technique which provides realistic low-dose images without the requirement of raw sinogram data. Methods: Two key characteristics of CT systems, the noise equivalent quanta (NEQ) and the algorithmic modulation transfer function (MTF), were measured for various combinations of object attenuation and tube currents by analyzing the noise power spectrum (NPS) of CT images obtained with a set of phantoms. Those measurements were used to develop a comprehensive CT noise model covering the reduced x-ray photon flux, object attenuation, system noise, and bow-tie filter, which was then employed to generate a simulated noise sinogram for the reduced-dose condition with the use of a synthetic sinogram generated from a reference CT image. The simulated noise sinogram was filtered with the algorithmic MTF and back-projected to create a noise CT image, which was then added to the reference CT image, finally providing a simulated reduced-dose CT image. The simulation performance was evaluated in terms of the degree of NPS similarity, the noise magnitude, the bow-tie filter effect, and the streak noise pattern at photon starvation sites with the set of phantom images. Results: The simulation results showed good agreement with actual low-dose CT images in terms of their visual appearance and in a quantitative evaluation test. The magnitude and shape of the NPS curves of the simulated low-dose images agreed well with those of real low-dose images, showing discrepancies of less than +/−3.2% in

  4. Realistic simulation of reduced-dose CT with noise modeling and sinogram synthesis using DICOM CT images

    SciTech Connect

    Won Kim, Chang; Kim, Jong Hyo

    2014-01-15

    Purpose: Reducing the patient dose while maintaining the diagnostic image quality during CT exams is the subject of a growing number of studies, in which simulations of reduced-dose CT with patient data have been used as an effective technique when exploring the potential of various dose reduction techniques. Difficulties in accessing raw sinogram data, however, have restricted the use of this technique to a limited number of institutions. Here, we present a novel reduced-dose CT simulation technique which provides realistic low-dose images without the requirement of raw sinogram data. Methods: Two key characteristics of CT systems, the noise equivalent quanta (NEQ) and the algorithmic modulation transfer function (MTF), were measured for various combinations of object attenuation and tube currents by analyzing the noise power spectrum (NPS) of CT images obtained with a set of phantoms. Those measurements were used to develop a comprehensive CT noise model covering the reduced x-ray photon flux, object attenuation, system noise, and bow-tie filter, which was then employed to generate a simulated noise sinogram for the reduced-dose condition with the use of a synthetic sinogram generated from a reference CT image. The simulated noise sinogram was filtered with the algorithmic MTF and back-projected to create a noise CT image, which was then added to the reference CT image, finally providing a simulated reduced-dose CT image. The simulation performance was evaluated in terms of the degree of NPS similarity, the noise magnitude, the bow-tie filter effect, and the streak noise pattern at photon starvation sites with the set of phantom images. Results: The simulation results showed good agreement with actual low-dose CT images in terms of their visual appearance and in a quantitative evaluation test. The magnitude and shape of the NPS curves of the simulated low-dose images agreed well with those of real low-dose images, showing discrepancies of less than +/−3.2% in

  5. Innovative Technology Reduces Power Plant Emissions-Commercialization Success

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde; Chung, Landy

    2004-01-01

    Overview of emission control system development: (1) Development of new oxidizer scrubber system to eliminate NOx waste and produce fertilizer (2) Technology licensed and a 1 to 3 MWatt-scale prototype installed on power plant (3) Development of method to oxidize NO to NO2 (4) Experience gained from licensing NASA technology.

  6. Innovative Technology Reduces Power Plant Emissions - Commercialization Success

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde

    2004-01-01

    Emission control system development includes: (1) Development of new oxidizer scrubber system to eliminate NOx waste and produce fertilizer (2) Technology licensed and a 1 to 3 MWatt-scale prototype installed on. power plant (3) Development of method to oxidize NO. to N02 (4) Experience gained from licensing NASA technology

  7. Utilizing intake-air oxygen-enrichment technology to reduce cold- phase emissions

    SciTech Connect

    Poola, R.B.; Ng, H.K.; Sekar, R.R.; Baudino, J.H.; Colucci, C.P.

    1995-12-31

    Oxygen-enriched combustion is a proven, serious considered technique to reduce exhaust hydrocarbons (HC) and carbon monoxide (CO) emissions from automotive gasoline engines. This paper presents the cold-phase emissions reduction results of using oxygen-enriched intake air containing about 23% and 25% oxygen (by volume) in a vehicle powered by a spark-ignition (SI) engine. Both engineout and converter-out emissions data were collected by following the standard federal test procedure (FTP). Converter-out emissions data were also obtained employing the US Environmental Protection Agency`s (EPA`s) ``Off-Cycle`` test. Test results indicate that the engine-out CO emissions during the cold phase (bag 1) were reduced by about 46 and 50%, and HC by about 33 and 43%, using nominal 23 and 25% oxygen-enriched air compared to ambient air (21% oxygen by volume), respectively. However, the corresponding oxides of nitrogen (NO{sub x}) emissions were increased by about 56 and 79%, respectively. Time-resolved emissions data indicate that both HC and CO emissions were reduced considerably during the initial 127 s of the cold-phase FTP, without any increase in NO, emissions in the first 25 s. Hydrocarbon speciation results indicate that all major toxic pollutants, including ozone-forming specific reactivity factors, such as maximum incremental reactivity (NUR) and maximum ozone incremental reactivity (MOIR), were reduced considerably with oxygen-enrichment. Based on these results, it seems that using oxygen-enriched intake air during the cold-phase FTP could potentially reduce HC and CO emissions sufficiently to meet future emissions standards. Off-cycle, converter-out, weighted-average emissions results show that both HC and CO emissions were reduced by about 60 to 75% with 23 or 25% oxygen-enrichment, but the accompanying NO{sub x}, emissions were much higher than those with the ambient air.

  8. Fundamental limits on 1/f frequency noise in rare-earth-metal-doped fiber lasers due to spontaneous emission

    NASA Astrophysics Data System (ADS)

    Foster, Scott

    2008-07-01

    It is proposed that observed 1/f laser frequency noise in rare-earth-metal-doped optical fiber lasers is caused by diffusion of local entropy fluctuations associated with random spontaneous emission events. This heat generation is directly associated with the broad emission spectrum of rare-earth-metal-doped laser glasses. Using data from a well characterized erbium-doped fiber laser, it is shown that the power spectral density of frequency fluctuations resulting from this mechanism is able to achieve excellent agreement with experiment. The proposed theory is expected to be generally applicable to broadly emitting solid-state gain media.

  9. Analysis of alternative pathways for reducing nitrogen oxide emissions

    EPA Science Inventory

    Strategies for reducing tropospheric ozone typically include modifying combustion processes to reduce the formation of nitrogen oxides (NOx) and applying control devices that remove NOx from the exhaust gases of power plants, industrial sources and vehicles. For portions of the ...

  10. Analysis of alternative pathways for reducing nitrogen oxide emissions

    EPA Science Inventory

    Strategies for reducing tropospheric ozone typically include modifying combustion processes to reduce the formation of nitrogen oxides (NOx) and applying control devices that remove NOx from the exhaust gases of power plants, industrial sources and vehicles. For portions of the ...

  11. [Comparison of methods for reducing residual noise in suprathreshold early auditory evoked potential registration].

    PubMed

    Mühler, R; von Specht, H; Pethe, J

    1998-07-01

    The level of residual noise in auditory brainstem responses (ABR) depends not only on the number of averages but also on the amplitude of background noise and on the frequency of artifacts. This paper describes the influence of digital filtering and of different methods of artifact suppression on the residual noise of ABRs. Amplitude of background noise was estimated for 1033 ABRs recorded under suprathreshold stimulation (70 and 90 dB nHL) in 251 subjects. In 45 ABR recordings in 15 subjects, all 4000 individual sweeps were stored for off-line simulation. The power spectrum of background noise was investigated using an FFT analyzer. A great variability of mean noise amplitude was found both between subjects and in the recordings for each subject. Depending on the slope of the analogue 100-Hz high-pass filter, mean RMS values of background noise of 4.2 microV (6 dB/Oct.) and 2.5 microV (12 dB/Oct.), respectively, were found. Digital high pass filtering before averaging was found to increase the signal-to-noise ratio (SNR) considerably. Results indicate that (i) effective suppression of low-frequency noise components can only be achieved by zero phase digital filtering and (ii) if clipping of noise amplitude to 25 microV is used, optimized artifact rejection as weighted averaging or adopted artifact rejection levels have only small effect on the SNR.

  12. 40 CFR 1036.610 - Innovative technology credits and adjustments for reducing greenhouse gas emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Innovative technology credits and adjustments for reducing greenhouse gas emissions. 1036.610 Section 1036.610 Protection of Environment... adjustments for reducing greenhouse gas emissions. (a) You may ask us to apply the provisions of this...

  13. 40 CFR 1036.610 - Innovative technology credits and adjustments for reducing greenhouse gas emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Innovative technology credits and adjustments for reducing greenhouse gas emissions. 1036.610 Section 1036.610 Protection of Environment... adjustments for reducing greenhouse gas emissions. (a) You may ask us to apply the provisions of this...

  14. 40 CFR 1036.610 - Innovative technology credits and adjustments for reducing greenhouse gas emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Innovative technology credits and adjustments for reducing greenhouse gas emissions. 1036.610 Section 1036.610 Protection of Environment... adjustments for reducing greenhouse gas emissions. (a) You may ask us to apply the provisions of this...

  15. Reduced Pain and Anxiety with Music and Noise-Canceling Headphones During Shockwave Lithotripsy.

    PubMed

    Karalar, Mustafa; Keles, Ibrahim; Doğantekin, Engin; Kahveci, Orhan Kemal; Sarici, Hasmet

    2016-06-01

    We assessed the effects of music and noise-canceling headphones (NCHs) on perceived patient pain and anxiety from extracorporeal shockwave lithotripsy (SWL). Patients with renal calculi scheduled for SWL were prospectively enrolled. All 89 patients between the ages of 19 and 80 years were informed about this study and then randomized into three groups: Group 1 (controls), no headphones and music; Group 2, music with NCHs (patients listened to Turkish classical music with NCHs during SWL); and Group 3, music with non-NCHs (patients listened to Turkish classical music with non-NCHs during SWL). Hemodynamic and respiratory parameters were recorded before and just after the SWL session. All patient visual analog scale (VAS) and State-Trait Anxiety Inventory (STAI) scores were recorded just after the SWL procedure. There were significant differences in VAS scores among the groups (5.1, 3.6, and 4.5, respectively, p < 0.001), including between Groups 2 and 3 (p = 0.018). There were also significant differences in STAI-State anxiety scores among the groups (43.1, 33.5, and 38.9, respectively, p = 0.001), including between Groups 2 and 3 (p = 0.04). Music therapy during SWL reduced pain and anxiety. Music therapy with NCHs was more effective for pain and anxiety reduction. To reduce pain and anxiety, nonpharmacologic therapies such as music therapy with NCHs during SWL should be investigated further and used routinely.

  16. 330 kWe Packaged CHP System with Reduced Emissions

    SciTech Connect

    Plahn, Paul; Keene, Kevin; Pendray, John

    2015-03-31

    The objective of this project was to develop a flexible, 330 kWe packaged Combined Heat and Power (CHP) system that can be deployed to commercial and light industrial applications at a lower total cost of ownership than current CHP solutions. The project resulted in a CHP system that is easy to use and inexpensive to install, offering world class customer support, while providing a low-emissions, higher-efficiency internal combustion engine for a CHP system of this size.

  17. More connected urban roads reduce US GHG emissions

    NASA Astrophysics Data System (ADS)

    Barrington-Leigh, Chris; Millard-Ball, Adam

    2017-04-01

    We quantify the importance of early action to tackle urban sprawl. We focus on the long-term nature of infrastructure decisions, specifically local roadways, which can lock in greenhouse gas emissions for decades to come. The location and interconnectedness of local roadways form a near-permanent backbone for the future layout of land parcels, buildings, and transportation options. We provide new estimates of the environmental impact of low-connectivity roads, characterized by cul-de-sacs and T-intersections, which we dub street-network sprawl. We find an elasticity of vehicle ownership with respect to street connectivity of -0.15—larger than suggested by previous research. We then apply this estimate to quantify the long-term emissions implications of alternative scenarios for street-network sprawl. On current trends alone, we project vehicle travel and emissions to fall by ˜3.2% over the 2015-2050 period, compared to a scenario where sprawl plateaus at its 1994 peak. Concerted policy efforts to increase street connectivity could more than triple these reductions to ˜8.8% by 2050. Longer-term reductions over the 2050-2100 period are more speculative, but could be more than 50% greater than those achieved by 2050. The longer the timescale over which mitigation efforts are considered, the more important it becomes to address the physical form of the built environment.

  18. Reducing flicker noise in chemical vapor deposition graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Arnold, Heather N.; Sangwan, Vinod K.; Schmucker, Scott W.; Cress, Cory D.; Luck, Kyle A.; Friedman, Adam L.; Robinson, Jeremy T.; Marks, Tobin J.; Hersam, Mark C.

    2016-02-01

    Single-layer graphene derived from chemical vapor deposition (CVD) holds promise for scalable radio frequency (RF) electronic applications. However, prevalent low-frequency flicker noise (1/f noise) in CVD graphene field-effect transistors is often up-converted to higher frequencies, thus limiting RF device performance. Here, we achieve an order of magnitude reduction in 1/f noise in field-effect transistors based on CVD graphene transferred onto silicon oxide substrates by utilizing a processing protocol that avoids aqueous chemistry after graphene transfer. Correspondingly, the normalized noise spectral density (10-7-10-8 μm2 Hz-1) and noise amplitude (4 × 10-8-10-7) in these devices are comparable to those of exfoliated and suspended graphene. We attribute the reduction in 1/f noise to a decrease in the contribution of fluctuations in the scattering cross-sections of carriers arising from dynamic redistribution of interfacial disorder.

  19. Greenhouse gas emissions during composting of dairy manure: Delaying pile mixing does not reduce overall emissions

    USDA-ARS?s Scientific Manuscript database

    The effect of the timing of pile mixing on greenhouse gas (GHG) emissions during dairy manure composting was determined using large flux chambers designed to completely cover replicate pilot-scale compost piles. GHG emissions from compost piles that were mixed at 2, 3, 4, or 5 weeks after initial c...

  20. Repeated exposure reduces the response to impulsive noise in European seabass.

    PubMed

    Radford, Andrew N; Lèbre, Laurie; Lecaillon, Gilles; Nedelec, Sophie L; Simpson, Stephen D

    2016-10-01

    Human activities have changed the acoustic environment of many terrestrial and aquatic ecosystems around the globe. Mounting evidence indicates that the resulting anthropogenic noise can impact the behaviour and physiology of at least some species in a range of taxa. However, the majority of experimental studies have considered only immediate responses to single, relatively short-term noise events. Repeated exposure to noise could lead to a heightened or lessened response. Here, we conduct two long-term (12 week), laboratory-based exposure experiments with European seabass (Dicentrarchus labrax) to examine how an initial impact of different sound types potentially changes over time. Naïve fish showed elevated ventilation rates, indicating heightened stress, in response to impulsive additional noise (playbacks of recordings of pile-driving and seismic surveys), but not to a more continuous additional noise source (playbacks of recordings of ship passes). However, fish exposed to playbacks of pile-driving or seismic noise for 12 weeks no longer responded with an elevated ventilation rate to the same noise type. Fish exposed long-term to playback of pile-driving noise also no longer responded to short-term playback of seismic noise. The lessened response after repeated exposure, likely driven by increased tolerance or a change in hearing threshold, helps explain why fish that experienced 12 weeks of impulsive noise showed no differences in stress, growth or mortality compared to those reared with exposure to ambient-noise playback. Considering how responses to anthropogenic noise change with repeated exposure is important both when assessing likely fitness consequences and the need for mitigation measures.

  1. Children with autism spectrum disorder have reduced otoacoustic emissions at the 1 kHz mid-frequency region.

    PubMed

    Bennetto, Loisa; Keith, Jessica M; Allen, Paul D; Luebke, Anne E

    2017-02-01

    Autism spectrum disorder (ASD) is a behaviorally diagnosed disorder of early onset characterized by impairment in social communication and restricted and repetitive behaviors. Some of the earliest signs of ASD involve auditory processing, and a recent study found that hearing thresholds in children with ASD in the mid-range frequencies were significantly related to receptive and expressive language measures. In addition, otoacoustic emissions have been used to detect reduced cochlear function in the presence of normal audiometric thresholds. We were interested then to know if otoacoustic emissions in children with normal audiometric thresholds would also reveal differences between children with ASD and typical developing (TD) controls in mid-frequency regions. Our objective was to specifically measure baseline afferent otoacoustic emissions (distortion-product otoacoustic emissions [DPOAEs]), transient-evoked otoacoustic emissions (TrOAEs), and efferent suppression, in 35 children with high-functioning ASD compared with 42 aged-matched TD controls. All participants were males 6-17 years old, with normal audiometry, and rigorously characterized via Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. Children with ASD had greatly reduced DPOAE responses in the 1 kHz frequency range, yet had comparable DPOAE responses at 0.5 and 4-8 kHz regions. Furthermore, analysis of the spectral features of TrOAEs revealed significantly decreased emissions in ASD in similar frequencies. No significant differences were noted in DPOAE or TrOAE noise floors, middle ear muscle reflex activity, or efferent suppression between children with ASD and TD controls. In conclusion, attention to specific-frequency deficits using non-invasive measures of cochlear function may be important in auditory processing impairments found in ASD. Autism Res 2017, 10: 337-345. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

  2. Airport noise

    NASA Technical Reports Server (NTRS)

    Pendley, R. E.

    1982-01-01

    The problem of airport noise at several airports and air bases is detailed. Community reactions to the noise, steps taken to reduce jet engine noise, and the effect of airport use restrictions and curfews on air transportation are discussed. The adverse effect of changes in allowable operational noise on airport safety and altenative means for reducing noise pollution are considered. Community-airport relations and public relations are discussed.

  3. Antioxidant loading reduces oxidative stress induced by high-energy impulse noise (blast) exposure.

    PubMed

    Elsayed, N M; Armstrong, K L; William, M T; Cooper, M F

    2000-11-30

    Detonation of explosives, firing of large caliber weapons and occupational explosions, professional or accidental, produce high-energy impulse noise (blast) waves characterized by a rapid rise in atmospheric pressure (overpressure) followed by gradual decay to ambient level. Exposure to blast waves causes injury, predominantly to the hollow organs such as ears and lungs. We have previously reported that blast exposure can induce free radical-mediated oxidative stress in the lung characterized by antioxidant depletion, lipid peroxidation, and hemoglobin (Hb) oxidation. In this study, we examined whether pre-loading, adequately fed rats, with pharmacological doses of antioxidants would reduce the response to blast. Sprague-Dawley rats weighing 300-350 g were loaded with either 800 IU vitamin E (VE), 1000 mg vitamin C (VC) or 25 mg lipoic acid (LA) for 3 consecutive days by gavage before exposure to blast. Both VE, and LA were dissolved in 2 ml corn oil, but VC in 2 ml water. After the 3-day antioxidant loading, the rats were divided into six groups (five rats per group), deeply anesthetized with sodium pentobarbital (60 mg/kg body weight), then exposed to a low-level blast (62+/-2 kPa peak pressure and 5 ms duration). A matched number of groups were sham exposed and served as controls. One hour after exposure, all rats were euthanized then blood, and lung tissue was analyzed. We found that antioxidant loading resulted in restored Hb oxygenation, and reduced lipid peroxidation. Lung tissue VE content was elevated after loading but VC did not change possibly due to their different bioavailability and saturation kinetics. These observations, suggest that brief antioxidant loading with pharmacological doses can reduce blast-induced oxidative stress, and may have occupational and clinical implications.

  4. Technology Opportunities to Reduce U.S. Greenhouse Gas Emissions

    SciTech Connect

    Pena, Federico

    1997-10-01

    This report serves as the technology basis of a needed national climate change technology strategy, with the confidence that a strong technology R&D program will deliver a portfolio of technologies with the potential to provide very substantial greenhouse gas emission reductions along with continued economic growth. Much more is needed to define such a strategy, including identification of complementary deployment policies and analysis to support the seeping and prioritization of R&D programs. A national strategy must be based upon governmental, industrial, and academic partnerships.

  5. Does modern helicopter construction reduce noise exposure in helicopter rescue operations?

    PubMed

    Küpper, Thomas; Jansing, Paul; Schöffl, Volker; van Der Giet, Simone

    2013-01-01

    During helicopter rescue operations the medical personnel are at high risk for hearing damage by noise exposure. There are two important factors to be taken into account: first, the extreme variability, with some days involving no exposure but other days with extreme exposure; second, the extreme noise levels during work outside the helicopter, e.g. during winch operations. The benefit of modern, less noisier constructions and the consequences for noise protection are still unknown. We estimated the noise exposure of the personnel for different helicopter types used during rescue operations in the Alps and in other regions of the world with special regard to the advanced types like Eurocopter EC 135 to compare the benefit of modern constructions for noise protection with earlier ones. The rescue operations over 1 year of four rescue bases in the Alps (Raron and Zermatt in Switzerland; Landeck and Innsbruck in Austria, n = 2731) were analyzed for duration of rescue operations (noise exposure). Noise levels were measured during rescue operations at defined points inside and outside the different aircraft. The setting is according to the European standard (Richtlinie 2003/10/EG Amtsblatt) and to Class 1 DIN/IEC 651. With both data sets the equivalent noise level L(eq8h) was calculated. For comparison it was assumed that all rescue operations were performed with a specific type of helicopter. Then model calculations for noise exposure by different helicopter types, such as Alouette IIIb, Alouette II 'Lama', Ecureuil AS350, Bell UH1D, Eurocopter EC135, and others were performed. Depending on modern technologies the situation for the personnel has been improved significantly. Nevertheless noise prevention, which includes noise intermissions in spare time, is essential. Medical checks of the crews by occupational medicine (e.g. 'G20' in Germany) are still mandatory.

  6. [Intervention to reduce the impact of light and noise on sleep in an emergency department observation area].

    PubMed

    Villamor Ordozgoiti, Alberto; Priu Parra, Inmaculada; España Salvador, María Carmen; Torres Valdés, Constancia; Bas Ciutad, María Pilar; Ponce Quílez, María Rosa

    2017-02-01

    To study quality of patient rest before and after an intervention to reduce nighttime light and noise in the emergency department observation area of an urban hospital. Quasi-experimental study in 2 groups before and after the intervention in the observation area of the Hospital Clínic de Barcelona. We administered a questionnaire about the quality of nighttime rest to assess the effect of light and noise on sleep. Light and noise were reduced by means of structural changes to the environment and through the introduction of protocols to modify how care plans were carried out at night. Fifty nurses participated in the pre-intervention study and 371 in the post-intervention study. Seventy-two percent and 91.37% of the patients reported resting well before and after the intervention, respectively (P< .001). Factors like pain, nursing care, or daytime naps do not affect sleep quality. Nighttime rest in emergency department observation areas is affected by ambient light and noise more than by other variables. Reducing light and noise at night can measurably improve patients' rest.

  7. About methods to reduce emissions of turbo charged engine gasoline direct injection

    NASA Astrophysics Data System (ADS)

    Neacsu, D.; Ivan, F.; Niculae, M.

    2017-08-01

    The paper aims to analyse and explain new methods applied on gasoline direct injection to reduce gas emissions and greenhouse effect. There are analysed the composition of emission inside the engine and which are the most harmful emission for the environment. Will be analysed the methods and systems which have a contribution to decrease emissions produced by the mixture of air and fuel. The paper contains details about after treatment systems which are designed to decrease gas emissions without any other negative consequence on the environment.

  8. ADVANCED DEHYDRATOR DESIGN SAVES GAS AND REDUCES HAP EMISSIONS

    EPA Science Inventory

    Glycol dehydrators remove water from gas pipe lines. An advanced dehydrator by Engineered Concepts, Farmington, NM, saves a significant amount of gas, while reducing hazardous air pollutants, volatile organic compounds and CO2 air pollutants

  9. Reducing greenhouse gas emissions: a duopoly market pricing competition and cooperation under the carbon emissions cap.

    PubMed

    Jian, Ming; He, Hua; Ma, Changsong; Wu, Yan; Yang, Hao

    2017-05-17

    This article studies the price competition and cooperation in a duopoly that is subjected to carbon emissions cap. The study assumes that in a departure from the classical Bertrand game, there is still a market for both firms' goods regardless of the product price, even though production capacity is limited by carbon emissions regulation. Through the decentralized decision making of both firms under perfect information, the results are unstable. The firm with the lower maximum production capacity under carbon emissions regulation and the firm with the higher maximum production capacity both seek market price cooperation. By designing an internal carbon credits trading mechanism, we can ensure that the production capacity of the firm with the higher maximum production capacity under carbon emissions regulation reaches price equilibrium. Also, the negotiation power of the duopoly would affect the price equilibrium.

  10. Dispersion-enhanced phase noise effects on reduced-guard-interval CO-OFDM transmission.

    PubMed

    Zhuge, Qunbi; Chen, Chen; Plant, David V

    2011-02-28

    Unlike conventional CO-OFDM systems, we show in this paper that reduced-guard-interval (RGI) CO-OFDM systems experience subcarrier-dependent phase noise (PN) from the local oscillator laser. This phenomenon manifests in RGI-CO-COFM systems because the chromatic dispersion (CD) induced walk-off becomes comparable to the OFDM symbol length. We term this phenomenon the dispersion enhanced PN (DEPN). In this work an analytical study of the impact of DEPN on CO-OFDM transmission is conducted. We develop a system-level analytical model and calculate the variance of the dispersion-induced subcarrier-dependent phase rotation term (PRT) using two different distribution patterns of pilot subcarriers (PS). Moreover, we present a bit error rate (BER) estimator to quantify the system performance degradation due to PRT. Numerical simulations are then performed to verify the analytical model. Finally, we propose a grouped maximum-likelihood (GML) phase estimation approach to mitigate the DEPN impairment, and demonstrate a 0.7-1.7 dB SNR improvement at BER=10⁻³ for typical 100 Gb/s RGI CO-OFDM systems.

  11. The problems of reducing the noise level on open sites of machine building plants and living areas

    NASA Astrophysics Data System (ADS)

    Bulkin, V. V.; Kalinichenko, M. V.

    2015-09-01

    In this article there is an analysis of using noise-absorbing screens on the basis Helmholtz resonator to reduce the level of acoustic noise on open industrial sites of machinebuilding plants and adjacent living areas. A design realization of this screen was considered, the characteristic of which is a variable depth of the resonator chamber and the change of the clearance of the resonator throat. The evaluation of the efficiency of using the screen was performed using experimental modeling with an acoustic chamber and a screen model. It was shown that in the majority of the cases there is some attenuation of the acoustic signal in the zone in front of the screen. A conclusion was made about the possibility of reducing noise level in industrial and living zone

  12. Challenges for Reducing Emissions of Black Carbon from the Transport Sector in Urban Areas

    NASA Astrophysics Data System (ADS)

    Zavala, M. A.; Molina, L. T.

    2013-05-01

    The transport sector is a large contributor of harmful gaseous and particulate emissions in many urban areas. Black carbon is a component of short-lived particulate matter emitted predominantly by freight, public transport, and heavy- duty trucks. Controlling the emissions of black carbon from the transport sector is important for mitigating its impacts on climate, ecosystems, and human health. However, reducing the emissions of black carbon from mobile sources may be a challenging task in many developing urban areas due to economic, social, and technical constrains. Several emissions control technologies offer a proven approach for reducing emissions of black carbon from diesel-powered mobile sources, but the accurate quantification of associated emissions benefits in developing urban areas is not well documented. We describe recent advances for the estimation of black carbon emissions from the transport sector in real world driving conditions and present examples of the potential benefits of implementing various emission control technologies in Mexico. The results can help in the identification of key factors that hinder the implementation of control emissions for reducing emissions of black carbon elsewhere.

  13. Description of the Role of Shot Noise in Spectroscopic Absorption and Emission Measurements with Photodiode and Photomultiplier Tube Detectors: Information for an Instrumental Analysis Course

    ERIC Educational Resources Information Center

    McClain, Robert L.; Wright, John C.

    2014-01-01

    A description of shot noise and the role it plays in absorption and emission measurements using photodiode and photomultiplier tube detection systems is presented. This description includes derivations of useful forms of the shot noise equation based on Poisson counting statistics. This approach can deepen student understanding of a fundamental…

  14. Description of the Role of Shot Noise in Spectroscopic Absorption and Emission Measurements with Photodiode and Photomultiplier Tube Detectors: Information for an Instrumental Analysis Course

    ERIC Educational Resources Information Center

    McClain, Robert L.; Wright, John C.

    2014-01-01

    A description of shot noise and the role it plays in absorption and emission measurements using photodiode and photomultiplier tube detection systems is presented. This description includes derivations of useful forms of the shot noise equation based on Poisson counting statistics. This approach can deepen student understanding of a fundamental…

  15. Nonlinear Microstructured Material to Reduce Noise and Vibrations at Low Frequencies

    NASA Astrophysics Data System (ADS)

    Lavazec, Deborah; Cumunel, Gwendal; Duhamel, Denis; Soize, Christian; Batou, Anas

    2016-09-01

    At low frequencies, for which the wavelengths are wide, the acoustic waves and the mechanical vibrations cannot easily be reduced in the structures at macroscale by using dissipative materials, contrarily to the middle- and high-frequency ranges. The final objective of this work is to reduce the vibrations and the induced noise on a broad low-frequency band by using a microstructured material by inclusions that are randomly arranged in the material matrix. The dynamical regimes of the inclusions will be imposed in the nonlinear domain in order that the energy be effectively pumped over a broad frequency band around the resonance frequency, due to the nonlinearity. The first step of this work is to design and to analyze the efficiency of an inclusion, which is made up of a hollow frame including a point mass centered on a beam. This inclusion is designed in order to exhibit nonlinear geometric effects in the low-frequency band that is observed. For this first step, the objective is to develop the simplest mechanical model that has the capability to roughly predict the experimental results that are measured. The second step, which is not presented in the paper, will consist in developing a more sophisticated nonlinear dynamical model of the inclusion. In this paper, devoted to the first step, it is proved that the nonlinearity induces an attenuation on a broad frequency band around the resonance, contrarily to its linear behavior for which the attenuation is only active in a narrow frequency band around the resonance. We will present the design in terms of geometry, dimension and materials for the inclusion, the experimental manufacturing of this system realized with a 3D printing system, and the experimental measures that have been performed. We compare the prevision given by the stochastic computational model with the measurements. The results obtained exhibit the physical attenuation over a broad low-frequency band, which were expected.

  16. Electromagnetic Signals and Earthquakes 2.0: Increasing Signals and Reducing Noise

    NASA Astrophysics Data System (ADS)

    Dunson, J. C.; Bleier, T.; Heraud, J. A.; Muller, S.; Lindholm, C.; Christman, L.; King, R.; Lemon, J.

    2013-12-01

    QuakeFinder has an international network of 150+ Magnetometers and air conductivity instruments located in California, Peru, Chile, Taiwan, and Greece. Since 2000, QuakeFinder has been collecting electromagnetic data and applying simple algorithms to identify and characterize electromagnetic signals that occur in the few weeks prior to earthquakes greater than M4.5. In this presentation, we show refinements to several aspects of our signal identification techniques that enhance detection of pre-earthquake patterns. Our magnetometers have been improved to show longer pulses, and we are now using second generation algorithms that have been refined to detect the proper shape of the earthquake-generated pulses and to allow individual site adjustments. Independent lightning strike data has also now been included to mask out lightning based on amplitude and distance from a given instrument site. Direction of arrival (Azimuth) algorithms have been added to identify patterns of pulse clustering that occur prior to nearby earthquakes. Likewise, positive and negative air ion concentration detection has been improved by building better enclosures, using stainless screens to eliminate insects and some dirt sources, conformal coating PC boards to reduce moisture contamination, and filtering out contaminated data segments based on relative humidity measurements at each site. Infra Red data from the western GOES satellite has been time-filtered, cloud-filtered, and compared to 3 year averages of each pixel's output (by seasonal month) to arrive at a relevant comparison baseline for each night's temperature/cooling slope. All these efforts have helped improve the detection of multiple, nearly simultaneous, electromagnetic signals due to earthquake preparation processes, while reducing false positive indications due to environmental noise sources.

  17. Dynamic optimisation of WWTP inflow to reduce total emission.

    PubMed

    Tränckner, J; Franz, T; Seggelke, K; Krebs, P

    2007-01-01

    A prerequisite for an integrated control of sewer and wastewater treatment plant (WWTP) is a capacity driven inflow control to WWTP. This requires reliable information about the current status of WWTP operation and its behaviour on varying hydraulic, COD and nutrient loads. So far most of the proposed control strategies are based on hypothetical modelling studies. In this paper the behaviour of three large WWTPs on increased storm water loads is analysed based on online measurements of several years. In all cases the main limiting factors for an increase of load were the sedimentation processes in the secondary clarifier and the nitrification capacity. In one case study predictive control strategies have been developed observing these processes which are backboned by effluent control. Tests using an integrated model of sewer and WWTP demonstrate that inflow control on emission load varies significantly with rain intensity.

  18. Coincident bursts of auroral kilometric radiation and VLF emissions associted with a type 3 solar radio noise event

    NASA Technical Reports Server (NTRS)

    Rosenberg, T. J.; Singh, S.; Wu, C. S.; Labelle, J.; Treumann, R. A.; Inan, U. S.; Lanzerotti, L. J.

    1995-01-01

    This paper examines an isolated magnetospheric VLF/radio noise event that is highly suggestive of the triggering of terrestrial auroral kilometric radiation (AKR) bu solar type III radio emission and of a close relation between AKR and broadband hiss. The solar type III burst was measured on polar HF riometers and was coincident with local dayside VLF/LF noise emission bursts at South Pole station. It was also coincident with AKR bursts detected onthe AMPTE/IRM satellite, at the same magnetic local time as South Pole. On the basis of the close association of AKR and VLF bursts, and from geometric considerations relating to wave propagation, it is likely that the AKR source was on the dayside and on field lines near South Pole station. The general level of geomagnetic activity was very low. However, an isolated magnetic impulse event (MIE) accompanied by a riometer absorption pulse was in progress when all of the VLF/radio noise bursts occurred. The very close association of the typew III burst at HF with the AKR is consistent with external stimulation of the AKR, is different, more immediate,triggering process than that implied by Calvert (1981) is invoked. It is suggested here that some of the HF solar radiant energy may decay into waves with frequences comparable to those of the AKR by paraetric excitation or some other process, thus providing the few background photons required for the generation of AKR by the WU and Lee (1979) cyclotron maser instability. The AKR, perhaps by modifying the magnetospheric electron velocity distribution, might have produced the observed VLF emissions. Alternatively, the VLF emissions may have arisen from the same anisotropic and unstable electron distribution function responsible for the AKR.

  19. Coincident bursts of auroral kilometric radiation and VLF emissions associted with a type 3 solar radio noise event

    NASA Technical Reports Server (NTRS)

    Rosenberg, T. J.; Singh, S.; Wu, C. S.; Labelle, J.; Treumann, R. A.; Inan, U. S.; Lanzerotti, L. J.

    1995-01-01

    This paper examines an isolated magnetospheric VLF/radio noise event that is highly suggestive of the triggering of terrestrial auroral kilometric radiation (AKR) bu solar type III radio emission and of a close relation between AKR and broadband hiss. The solar type III burst was measured on polar HF riometers and was coincident with local dayside VLF/LF noise emission bursts at South Pole station. It was also coincident with AKR bursts detected onthe AMPTE/IRM satellite, at the same magnetic local time as South Pole. On the basis of the close association of AKR and VLF bursts, and from geometric considerations relating to wave propagation, it is likely that the AKR source was on the dayside and on field lines near South Pole station. The general level of geomagnetic activity was very low. However, an isolated magnetic impulse event (MIE) accompanied by a riometer absorption pulse was in progress when all of the VLF/radio noise bursts occurred. The very close association of the typew III burst at HF with the AKR is consistent with external stimulation of the AKR, is different, more immediate,triggering process than that implied by Calvert (1981) is invoked. It is suggested here that some of the HF solar radiant energy may decay into waves with frequences comparable to those of the AKR by paraetric excitation or some other process, thus providing the few background photons required for the generation of AKR by the WU and Lee (1979) cyclotron maser instability. The AKR, perhaps by modifying the magnetospheric electron velocity distribution, might have produced the observed VLF emissions. Alternatively, the VLF emissions may have arisen from the same anisotropic and unstable electron distribution function responsible for the AKR.

  20. Coincident bursts of auroral kilometric radiation and VLF emissions associated with a type III solar radio noise event

    SciTech Connect

    Rosenberg, T.J.; Singh, S.; Wu, C.S.; LaBelle, J.; Treumann, R.A.; Inan, U.S.; Lanzerotti, L.J.

    1995-01-01

    This paper examines an isolated magnetospheric VLF/radio noise event that is highly suggestive of the triggering of terrestrial auroral kilometric radiation (AKR) by solar type III radio emission and of a close relation between AKR and broadband hiss. The solar type III burst was measured on polar HF riometers and was coincident with local dayside VLF/LF noise emission bursts at South Pole station. It was also coincident with AKR bursts detected on the AMPTE/IRM satellite, at the same magnetic local time as South Pole. On the basis of the close association of AKR and VLF bursts, and from geometrical considerations relating to wave propagnation, it is likely that the AKR source was on the dayside and on field lines near South Pole station. The general level of geomagnetic activity was very low. However, an isolated magnetic impulse event (MIE) accompanied by a riometer absorption pulse was in progress when all of the VLF/radio noise bursts occurred. The very close association of the type III burst at HF with the AKR is consistent with external stimulation of the AKR, if a different, more immediate, triggering process than that implied by Calvert is invoked. It is suggested here that some of the HF solar radiant energy may decay into waves with frequencies comparable to those of the AKR by parametric excitation or some other process, thus providing the few background photons required for the generation of AKR by the Wu and Lee cyclotron maser instability. The AKR, perhaps by modifying the magnetospheric electron velocity distribution, might have produced the observed VLF emissions. Alternatively, the VLF emissions may have arisen from the same anisotropic and unstable electron distribution function responsible for the AKR. 41 refs., 5 figs.

  1. Highly doped polycrystalline silicon microelectrodes reduce noise in neuronal recordings in vivo.

    PubMed

    Saha, Rajarshi; Jackson, Nathan; Patel, Chetan; Muthuswamy, Jit

    2010-10-01

    The aims of this study are to 1) experimentally validate for the first time the nonlinear current-potential characteristics of bulk doped polycrystalline silicon in the small amplitude voltage regimes (0-200 μV) and 2) test if noise amplitudes ( 0-15 μV ) from single neuronal electrical recordings get selectively attenuated in doped polycrystalline silicon microelectrodes due to the above property. In highly doped polycrystalline silicon, bulk resistances of several hundred kilo-ohms were experimentally measured for voltages typical of noise amplitudes and 9-10 kΩ for voltages typical of neural signal amplitudes ( > 150-200 μV). Acute multiunit measurements and noise measurements were made in n=6 and n=8 anesthetized adult rats, respectively, using polycrystalline silicon and tungsten microelectrodes. There was no significant difference in the peak-to-peak amplitudes of action potentials recorded from either microelectrode (p > 0.10). However, noise power in the recordings from tungsten microelectrodes (26.36 ±10.13 pW) was significantly higher than the corresponding value in polycrystalline silicon microelectrodes (7.49 ±2.66 pW). We conclude that polycrystalline silicon microelectrodes result in selective attenuation of noise power in electrical recordings compared to tungsten microelectrodes. This reduction in noise compared to tungsten microelectrodes is likely due to the exponentially higher bulk resistances offered by highly doped bulk polycrystalline silicon in the range of voltages corresponding to noise in multiunit measurements.

  2. Diesel fuel containing wax oxidates to reduce particulate emissions

    SciTech Connect

    Sprague, H.G.; Sweeney, W.M.

    1980-09-16

    Addition of 0.1 to 1.5 percent by weight of wax oxidates to a diesel fuel is found to reduce the amount of soot and invisible particles produced when the fuel is used in a diesel engine. The wax oxidates act synergistically with fuel-soluble organometallic compounds such as alkyl cyclopentadienyl manganese tricarbonyl complex salts in reducing particulates. The wax oxidates used have a ratio of neutralization number to saponification number below about 0.40 and a saybolt universal viscosity at 210* F. Higher than 1600.

  3. Acute partial sleep deprivation due to environmental noise increases weight gain by reducing energy expenditure in rodents.

    PubMed

    Parrish, Jennifer B; Teske, Jennifer A

    2017-01-01

    Chronic partial sleep deprivation (SD) by environmental noise exposure increases weight gain and feeding in rodents, which contrasts weight loss after acute SD by physical methods. This study tested whether acute environmental noise exposure reduced sleep and its effect on weight gain, food intake, physical activity, and energy expenditure (EE). It was hypothesized that acute exposure would (1) increase weight gain and feeding and (2) reduce sleep, physical activity, and EE (total and individual components); and (3) behavioral changes would persist throughout recovery from SD. Three-month old male Sprague-Dawley rats slept ad libitum, were noise exposed (12-h light cycle), and allowed to recover (36 h). Weight gain, food intake, sleep/wake, physical activity, and EE were measured. Acute environmental noise exposure had no effect on feeding, increased weight gain (P < 0.01), and reduced sleep (P < 0.02), physical activity (P < 0.03), total EE (P < 0.05), and several components (P < 0.05). Reductions in EE and physical activity persisted during recovery. Reductions in EE during sleep, rest, and physical activity reduce total EE and contribute to weight gain during acute SD and recovery from SD. These data emphasize the importance of increasing physical activity after SD to prevent obesity. © 2016 The Obesity Society.

  4. Using a depolarizer to reduce the effect of phase-induced intensity noise in fiber optics bit rate limiters

    NASA Astrophysics Data System (ADS)

    Tur, Moshe; Carmeli, Ran

    1993-08-01

    A Lyot depolarizer is used in a bit-rate-limiter of the Mach-Zehnder type in order to reduce the phase induced intensity noise, which otherwise, sets a floor on the bit error ratio. Results show an improvement of 3 dB, at the expense of longer arms and a more complicated design.

  5. Gamma-magnetic normalization - new effect to reduce flux-gate magnetometer noise level

    NASA Astrophysics Data System (ADS)

    Korepanov, V.

    2012-04-01

    It is the author's opinion confirmed by numerous experiments, that the FGM noise level (NL) is determined not by Barkhausen jumps during the core remagnetization from positive to negative state as the majority of designers believe, but by non-repeatability of the magnetic domains transition from negative to positive states and back. This shows the way how to reduce the magnetic noise: to manufacture the magnetic material with a structure which will create conditions for magnetic domain walls to glide easily and uniformly when changing their orientation leading to minimal efforts at cyclic remagnetization. Ideally, such a material may be represented as a solid "liquid" with freely floating uniform magnetic domains without walls friction. To reduce the specific NL of the materials, several post-melting processing technologies were developed. A set of experiments made by many investigators has shown that the best results gives the magnetic materials annealing in vacuum or in any inert gas applying by this during all annealing time the alternative magnetic field, imitating core excitation field during FGM operation. If to accept the "solid liquid" model, this mechanism of NL decreasing has clear physical explanation: permanent re-magnetization of domains leads to the structural improvements favorable namely for the homogenization of transitions, rise of temperature gives necessary energy for the impurities liquidation. Probably, M. Acuna was the first who reported that during FGM operation in space its NL is decreasing with time and attributed this to the relaxation of mechanical stresses in the core material in weightlessness conditions [1]. We studied in details the conditions in which the core material is in space: weightlessness, vacuum and radiation. Mechanical stresses relaxation hypothesis was rejected because the internal forces in any solid body are much stronger as those to which a gravity force might have influence. Also the tests of FGM sensor in vacuum

  6. An optimal control model for reducing and trading of carbon emissions

    NASA Astrophysics Data System (ADS)

    Guo, Huaying; Liang, Jin

    2016-03-01

    A stochastic optimal control model of reducing and trading for carbon emissions is established in this paper. With considerations of reducing the carbon emission growth and the price of the allowances in the market, an optimal policy is searched to have the minimum total costs to achieve the agreement of emission reduction targets. The model turns to a two-dimension HJB equation problem. By the methods of reducing dimension and Cole-Hopf transformation, a semi-closed form solution of the corresponding HJB problem under some assumptions is obtained. For more general cases, the numerical calculations, analysis and comparisons are presented.

  7. A performance standards approach to reducing CO{sub 2} emissions from electric power plants

    SciTech Connect

    Rubin, E.S.

    2009-06-15

    The CO{sub 2} emission performance standard policies outlined in this paper could complement a cap-and-trade program that puts a price on carbon and serve to significantly reduce the CO{sub 2} emissions from coal use for electricity generation. Emission performance standards have a long history in the United States and have been successfully used to control emissions of various air pollutants from electric generators. This paper explores the rationale for using emission performance standards and describes the various types of performance standard policies. Emission performance standards that address CO{sub 2} emissions could promote the deployment of carbon capture and storage technology coupled with new and existing coal-fueled electric power plants. 28 refs., 4 figs., 4 tabs.

  8. SLMRACE: a noise-free RACE implementation with reduced computational time

    NASA Astrophysics Data System (ADS)

    Chauvin, Juliet; Provenzi, Edoardo

    2017-05-01

    We present a faster and noise-free implementation of the RACE algorithm. RACE has mixed characteristics between the famous Retinex model of Land and McCann and the automatic color equalization (ACE) color-correction algorithm. The original random spray-based RACE implementation suffers from two main problems: its computational time and the presence of noise. Here, we will show that it is possible to adapt two techniques recently proposed by Banić et al. to the RACE framework in order to drastically decrease the computational time and noise generation. The implementation will be called smart-light-memory-RACE (SLMRACE).

  9. Acoustic vector sensor beamforming reduces masking from underwater industrial noise during passive monitoring.

    PubMed

    Thode, Aaron M; Kim, Katherine H; Norman, Robert G; Blackwell, Susanna B; Greene, Charles R

    2016-04-01

    Masking from industrial noise can hamper the ability to detect marine mammal sounds near industrial operations, whenever conventional (pressure sensor) hydrophones are used for passive acoustic monitoring. Using data collected from an autonomous recorder with directional capabilities (Directional Autonomous Seafloor Acoustic Recorder), deployed 4.1 km from an arctic drilling site in 2012, the authors demonstrate how conventional beamforming on an acoustic vector sensor can be used to suppress noise arriving from a narrow sector of geographic azimuths. Improvements in signal-to-noise ratio of up to 15 dB are demonstrated on bowhead whale calls, which were otherwise undetectable using conventional hydrophones.

  10. Reducing the impact of wind noise on cochlear implant processors with two microphones

    PubMed Central

    Kokkinakis, Kostas; Cox, Casey

    2014-01-01

    Behind-the-ear (BTE) processors of cochlear implant (CI) devices offer little to almost no protection from wind noise in most incidence angles. To assess speech intelligibility, eight CI recipients were tested in 3 and 9 m/s wind. Results indicated that speech intelligibility decreased substantially when the wind velocity, and in turn the wind sound pressure level, increased. A two-microphone wind noise suppression strategy was developed. Scores obtained with this strategy indicated substantial gains in speech intelligibility over other conventional noise reduction strategies tested. PMID:24815292

  11. Reducing the impact of wind noise on cochlear implant processors with two microphones.

    PubMed

    Kokkinakis, Kostas; Cox, Casey

    2014-05-01

    Behind-the-ear (BTE) processors of cochlear implant (CI) devices offer little to almost no protection from wind noise in most incidence angles. To assess speech intelligibility, eight CI recipients were tested in 3 and 9 m/s wind. Results indicated that speech intelligibility decreased substantially when the wind velocity, and in turn the wind sound pressure level, increased. A two-microphone wind noise suppression strategy was developed. Scores obtained with this strategy indicated substantial gains in speech intelligibility over other conventional noise reduction strategies tested.

  12. A Systems Approach to Reducing Institutional GHG Emissions

    ERIC Educational Resources Information Center

    Williamson, Sean R.

    2012-01-01

    Purpose: The purpose of this paper is to establish necessity and methods for considering greenhouse gas (GHG) mitigation policies at a system-level. The research emphasizes connecting narrowly focused GHG mitigation objectives (e.g. reduce single occupancy vehicle travel) with broader institutional objectives (e.g. growth in student population) to…

  13. Analysis of alternative pathways for reducing nitrogen oxide emissions.

    PubMed

    Loughlin, Daniel H; Kaufman, Katherine R; Lenox, Carol S; Hubbell, Bryan J

    2015-09-01

    Strategies for reducing tropospheric ozone (O3) typically include modifying combustion processes to reduce the formation of nitrogen oxides (NOx) and applying control devices that remove NOx from the exhaust gases of power plants, industrial sources and vehicles. For portions of the U.S., these traditional controls may not be sufficient to achieve the National Ambient Air Quality Standard for ozone. We apply the MARKet ALlocation (MARKAL) energy system model in a sensitivity analysis to explore whether additional NOx reductions can be achieved through extensive electrification of passenger vehicles, adoption of energy efficiency and conservation measures within buildings, and deployment of wind and solar power in the electric sector. Nationally and for each region of the country, we estimate the NOx implications of these measures. Energy efficiency and renewable electricity are shown to reduce NOx beyond traditional controls. Wide-spread light duty vehicle electrification produces varied results, with NOx increasing in some regions and decreasing in others. However, combining vehicle electrification with renewable electricity reduces NOx in all regions. State governments are charged with developing plans that demonstrate how air quality standards will be met and maintained. The results presented here provide an indication of the national and regional NOx reductions available beyond traditional controls via extensive adoption of energy efficiency, renewable electricity, and vehicle electrification.

  14. A Systems Approach to Reducing Institutional GHG Emissions

    ERIC Educational Resources Information Center

    Williamson, Sean R.

    2012-01-01

    Purpose: The purpose of this paper is to establish necessity and methods for considering greenhouse gas (GHG) mitigation policies at a system-level. The research emphasizes connecting narrowly focused GHG mitigation objectives (e.g. reduce single occupancy vehicle travel) with broader institutional objectives (e.g. growth in student population) to…

  15. Signal-to-noise ratios in IUE SWP-LO spectra of chromospheric emission-line sources

    NASA Astrophysics Data System (ADS)

    Ayres, Thomas R.

    1990-12-01

    The short-wavelength-prime (SWP) detector of the International Ultraviolet Explorer should operate near the photon-counting limit, but the noise levels in flat-field images are several times higher. The exaggerated noise can be traced to the incomplete removal of the pixel-to-pixel granularity of the television frames by the prevailing spectral image processing system. An empirical noise model for the current-epoch photometric linearization strategy and one for a hypothetical processing system that achieves complete flat fielding of the raw images are derived. A formula is then proposed to predict the signal-to-noise ratio in the measured flux of an emission line (possibly superimposed on a smooth continuum) in an IUE low-dispersion (5 A resolution) far-ultraviolet (1150 A-1950 A) spectrum as recorded with the SWP camera. For illustration, the formula is specialized to the important C IV 1549 A feature of F-K stars. The S/N relation permits one to determine sensitivity limits, upper limits in faint exposures, and optimum exposure times.

  16. Signal-to-noise ratios in IUE SWP-LO spectra of chromospheric emission-line sources

    NASA Technical Reports Server (NTRS)

    Ayres, Thomas R.

    1990-01-01

    The short-wavelength-prime (SWP) detector of the International Ultraviolet Explorer should operate near the photon-counting limit, but the noise levels in flat-field images are several times higher. The exaggerated noise can be traced to the incomplete removal of the pixel-to-pixel granularity of the television frames by the prevailing spectral image processing system. An empirical noise model for the current-epoch photometric linearization strategy and one for a hypothetical processing system that achieves complete flat fielding of the raw images are derived. A formula is then proposed to predict the signal-to-noise ratio in the measured flux of an emission line (possibly superimposed on a smooth continuum) in an IUE low-dispersion (5 A resolution) far-ultraviolet (1150 A-1950 A) spectrum as recorded with the SWP camera. For illustration, the formula is specialized to the important C IV 1549 A feature of F-K stars. The S/N relation permits one to determine sensitivity limits, upper limits in faint exposures, and optimum exposure times.

  17. Combined influence of hydrostatic pressure and temperature on interband emission energy of impurity doped quantum dots in presence of noise

    NASA Astrophysics Data System (ADS)

    Bera, Aindrila; Ghosh, Manas

    2016-11-01

    We explore the profiles of interband emission energy (IEE) of impurity doped quantum dots (QDs) under the simultaneous influence of hydrostatic pressure (HP) and temperature (T) and in presence and absence of Gaussian white noise. Noise has been incorporated to the system additively and multiplicatively. In this regard, modulation of IEE by the variation of several other relevant quantities such as electric field, magnetic field, confinement potential, dopant location, dopant potential and aluminium concentration has also been investigated. Gradual alteration of HP and T affects IEE discernibly. Inclusion of noise has been found to enhance or deplete the IEE depending upon its mode of application. Moreover, under given conditions of temperature and pressure, the difference between the impurity-free ground state energy and the binding energy appears to be crucial in determining whether or not the profiles of IEE would resemble that of binding energy. The findings reveal fascinating role played by noise in tailoring the IEE of doped QD system under conspicuous presence of hydrostatic pressure and temperature.

  18. Water-washable ink system reduces printers' hazardous emissions

    SciTech Connect

    Kratch, K.

    1994-08-01

    Printing industry solvents contain large quantities of volatile organic compounds (VOCs), a major contributor to air pollution in that industry. Because most printing inks contain non-water-soluble petroleum, organic solvents have been necessary to clean presses using those inks. However, under proposed control technique guidelines for lithographic printers issued by the Environmental Protection Agency (EPA), printing-press wash solutions could contain no more than 30% VOCs. Deluxe Corp., a St. Paul, Minn.-based lithographic printer, recognized that stiffer emissions rules could mean harsh penalties for non-compliance and, in 1990, began developing a water-based press wash that would meet the guidelines. Deluxe last year introduced a 100% vegetable oil-based ink that becomes water-washable when exposed to the company's water-based press-wash solution. The solvent-free system eliminates VOCs and hazardous wastes associated with printing, contains no chemicals considered hazardous by EPA, uses no non-renewable resources, and works with existing printing equipment and processes. The system also eliminates water and soil contamination risks associated with laundering or landfilling solvent-saturated shop towels, saves money by eliminating the need to pay for hazardous waste disposal and provides relief to employees who complain about the strong odors of traditional press-wash solvents.

  19. Emission of sound from axisymmetric turbulence convected by a mean flow with application to jet noise

    NASA Technical Reports Server (NTRS)

    Goldstein, M. E.; Rosenbaum, B. M.

    1972-01-01

    A model, based on Lighthill's theory, for predicting aerodynamic noise from a turbulent shear flow is developed. This model is a generalization of the one developed by Ribner. Unlike Ribner's model, it does not require that the turbulent correlations factor into space and time-dependent parts. It replaces his assumption of isotropic. turbulence by the more realistic one of axisymmetric turbulence. The implications of the model for jet noise are discussed.

  20. Method and apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, Rhett L.; Ambrose, W. Patrick; Demas, James N.; Goodwin, Peter M.; Johnson, Mitchell E.; Keller, Richard A.; Petty, Jeffrey T.; Schecker, Jay A.; Wu, Ming

    1998-01-01

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

  1. Method and apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, R.L.; Ambrose, W.P.; Demas, J.N.; Goodwin, P.M.; Johnson, M.E.; Keller, R.A.; Petty, J.T.; Schecker, J.A.; Wu, M.

    1998-10-27

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region. 6 figs.

  2. EPA Awards $1.9 Million to Reduce Diesel Emissions in Alaska, Idaho, Oregon and Washington

    EPA Pesticide Factsheets

    (Seattle - October 27, 2015) The U.S. Environmental Protection Agency has awarded $1,919,653 in Diesel Emission Reduction Act (DERA) funding to Alaska, Idaho, Oregon, and Washington to reduce diesel, greenhouse gas and black carbon emissions from large pol

  3. Reducing Energy Cost and Greenhouse Gas Emission in the Corporate Sector, a Delphi Study

    ERIC Educational Resources Information Center

    Kramer, Maxim L.

    2013-01-01

    The study is titled "Reducing energy cost and GreenHouse Gas emission in the corporate sector, A Delphi Study". The study applied the Delphi methodology and focused on the Green IT solutions that can help the modern corporate organizations with less than 1000 employees to decrease their energy costs and GHG emissions. The study presents…

  4. APPLICATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE INDOOR AIR EMISSIONS FROM ENGINEERED WOOD PRODUCTS

    EPA Science Inventory

    The report gives results of an investigation of pollution prevention options to reduce indoor emissions from a type of finished engineered wood. Emissions were screened from four types of finished engineered wood: oak-veneered particleboard coated and cured with a heat-curable, a...

  5. Reducing N2O emissions from orchard using subsurfce drip irrigation

    USDA-ARS?s Scientific Manuscript database

    Agricultural soil is the major source for N2O emissions. Minimizing N2O emissions along with increasing N use efficiency, reducing leaching loss, and maintaining crop economic yield and quality can lead to increased sustainability of crop production. The main objective of this research is to evaluat...

  6. APPLICATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE INDOOR AIR EMISSIONS FROM ENGINEERED WOOD PRODUCTS

    EPA Science Inventory

    The report gives results of an investigation of pollution prevention options to reduce indoor emissions from a type of finished engineered wood. Emissions were screened from four types of finished engineered wood: oak-veneered particleboard coated and cured with a heat-curable, a...

  7. Reducing Energy Cost and Greenhouse Gas Emission in the Corporate Sector, a Delphi Study

    ERIC Educational Resources Information Center

    Kramer, Maxim L.

    2013-01-01

    The study is titled "Reducing energy cost and GreenHouse Gas emission in the corporate sector, A Delphi Study". The study applied the Delphi methodology and focused on the Green IT solutions that can help the modern corporate organizations with less than 1000 employees to decrease their energy costs and GHG emissions. The study presents…

  8. Microbial inoculants as tools for reducing nitrous oxide emissions from soil

    USDA-ARS?s Scientific Manuscript database

    Over the past few decades, emissions of nitrous oxide (N2O) have increased worldwide due to several factors, including increases in cultivated crop area, use of synthetic nitrogen fertilizers, and livestock production. New management tools are needed to reduce N2O emissions from production agricultu...

  9. Application of microbial inoculants as tools for reducing nitrous oxide emissions from different nitrogen fertilizers

    USDA-ARS?s Scientific Manuscript database

    Emissions of nitrous oxide (N2O) are increasing due to several factors, including increased use of nitrogen fertilizers. New management tools are needed to reduce N2O emissions from production agriculture. One potential such tool is the use of microbial inoculants, which are increasingly being used ...

  10. U.S. EPA Awards $3.2 Million to Reduce Diesel Emissions in California

    EPA Pesticide Factsheets

    SAN FRANCISCO - The U.S. Environmental Protection Agency has awarded $3,258,639 in Diesel Emission Reduction Act (DERA) funding to California to reduce diesel, greenhouse gas and black carbon emissions from large polluting diesel sources, such as tr

  11. Methods of reducing low frequency cabin noise and sonically induced stresses, based on the intrinsic structural tuning concept

    NASA Technical Reports Server (NTRS)

    Sengupta, G.

    1977-01-01

    Control of low frequency interior noise has been difficult in all commercial and general aviation aircraft, since the existing sound attenuation techniques are less effective at these frequencies. Therefore low frequency cabin noise and sonically induced stresses can be reduced mainly by a proper design of the fuselage structure. For this purpose, a concept based on intrinsic tuning and damping of fuselage structural elements has been under development at Boeing for the past three years. This paper describes the results of some laboratory and field tests that were conducted for evaluation of the concept.

  12. An optimal energy estimator to reduce correlated noise for the EXO-200 light readout

    NASA Astrophysics Data System (ADS)

    Davis, C. G.; Hall, C.; Albert, J. B.; Barbeau, P. S.; Beck, D.; Belov, V.; Breidenbach, M.; Brunner, T.; Burenkov, A.; Cao, G. F.; Cen, W. R.; Chambers, C.; Cleveland, B.; Coon, M.; Craycraft, A.; Daniels, T.; Danilov, M.; Daugherty, S. J.; Davis, J.; Delaquis, S.; Der Mesrobian-Kabakian, A.; DeVoe, R.; Didberidze, T.; Dilling, J.; Dolgolenko, A.; Dolinski, M. J.; Dunford, M.; Fairbank, W., Jr.; Farine, J.; Feldmeier, W.; Feyzbakhsh, S.; Fierlinger, P.; Fudenberg, D.; Gornea, R.; Graham, K.; Gratta, G.; Hughes, M.; Jewell, M. J.; Johnson, A.; Johnson, T. N.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Killick, R.; Koffas, T.; Kravitz, S.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Leonard, D. S.; Licciardi, C.; Lin, Y. H.; Ling, J.; MacLellan, R.; Marino, M. G.; Mong, B.; Moore, D.; Njoya, O.; Nelson, R.; Odian, A.; Ostrovskiy, I.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Retière, F.; Rowson, P. C.; Russell, J. J.; Schubert, A.; Sinclair, D.; Smith, E.; Stekhanov, V.; Tarka, M.; Tolba, T.; Tsang, R.; Twelker, K.; Vuilleumier, J.-L.; Waite, A.; Walton, J.; Walton, T.; Weber, M.; Wen, L. J.; Wichoski, U.; Wood, J.; Yang, L.; Yen, Y.-R.; Zeldovich, O. Ya.

    2016-07-01

    The energy resolution of the EXO-200 detector is limited by electronics noise in the measurement of the scintillation response. Here we present a new technique to extract optimal scintillation energy measurements for signals split across multiple channels in the presence of correlated noise. The implementation of these techniques improves the energy resolution of the detector at the neutrinoless double beta decay Q-value from [1.9641 ± 0.0039]% to [1.5820 ± 0.0044]%.

  13. Study on direct sound reduction structure for reducing noise generated by vibrating solids

    NASA Astrophysics Data System (ADS)

    Endo, M.; Kim, Y. S.

    2013-05-01

    A direct sound reduction structure is proposed as a new method for reducing noise generated by vibrating solids. The proposed method involves directly attaching a hard sound absorbing material with a honeycomb structure to the surfaces of vibrating solids to provide a moderate amount of back air space. Using a one-dimensional acoustic-field model, the fundamental sound reduction characteristics are investigated theoretically and experimentally, and the effectiveness of the proposed concept is verified. In the theoretical analysis, an analytical model with a sinusoidally excited rigid-frame sound reduction structure is considered. In the experiments, a one-dimensional acoustic tube is used to determine the sound reduction ratios for both stationary excitation and non-stationary impulsive excitation as a function of frequency. Furthermore, in order to verify the practical usefulness of this approach, an experimental study on sound reduction in a three-dimensional acoustic field is carried out using either a rigid piston plate surrounded by a baffle or a flexible flat plate with different vibration modes as vibrating bases. The results indicate that the sound reduction ratio has a quasi-periodic form that depends on the thickness of the back air space and the sound frequency, and a sound pressure reduction of approximately 80 percent (-14 dB) is observed around the minima. In addition, the average reduction in the frequency range 0.5-5 kHz is approximately 40 percent (-4.4 dB). The results obtained in this study are expected to act as useful indices for designing a nearly optimum sound reduction structure if the target frequency is known in advance.

  14. A simplified approach for the calculation of acoustic emission in the case of friction-induced noise and vibration

    NASA Astrophysics Data System (ADS)

    Soobbarayen, K.; Besset, S.; Sinou, J.-. J.

    2015-01-01

    The acoustic response associated with squeal noise radiations is a hard issue due to the need to consider non-linearities of contact and friction, to solve the associated nonlinear dynamic problem and to calculate the noise emissions due to self-excited vibrations. In this work, the focus is on the calculation of the sound pressure in free space generated during squeal events. The calculation of the sound pressure can be performed by the Boundary Element Method (BEM). The inputs of this method are a boundary element model, a field of normal velocity characterized by a unique frequency. However, the field of velocity associated with friction-induced vibrations is composed of several harmonic components. So, the BEM equation has to be solved for each frequency and in most cases, the number of harmonic components is significant. Therefore, the computation time can be prohibitive. The reduction of the number of harmonic component is a key point for the quick estimation of the squeal noise. The proposed approach is based on the detection and the selection of the predominant harmonic components in the mean square velocity. It is applied on two cases of squeal and allows us to consider only few frequencies. In this study, a new method will be proposed in order to quickly well estimate the noise emission in free space. This approach will be based on an approximated acoustic power of brake system which is assumed to be a punctual source, an interpolated directivity and the decrease of the acoustic power levels. This method is applied on two classical cases of squeal with one and two unstable modes. It allows us to well reconstruct the acoustic power levels map. Several error estimators are introduced and show that the reconstructed field is close to the reference calculated with a complete BEM.

  15. Soy Biodiesel Emissions Have Reduced Inflammatory Effects Compared to Diesel Emissions in Healthy and Allergic Mice

    EPA Science Inventory

    Toxicity of exhaust from combustion of petroleum diesel (BO), soy-based biodiesel (B100), or a 20% biodiesel/80% petrodiesel mix (B20) was compared in healthy and house dust mite (HDM)-allergic mice. Fuel emissions were diluted to target fine particulate matter (PM2.5) conrentrat...

  16. Soy Biodiesel Emissions Have Reduced Inflammatory Effects Compared to Diesel Emissions in Healthy and Allergic Mice

    EPA Science Inventory

    Toxicity of exhaust from combustion of petroleum diesel (BO), soy-based biodiesel (B100), or a 20% biodiesel/80% petrodiesel mix (B20) was compared in healthy and house dust mite (HDM)-allergic mice. Fuel emissions were diluted to target fine particulate matter (PM2.5) conrentrat...

  17. Evaluation of TIF to reduce fumigant emissions and the potential to use reduced rates

    USDA-ARS?s Scientific Manuscript database

    Strawberry growers in California rely heavily on soil fumigation to assure profitable berries and high yields. However, the adverse impact on air quality from fumigant emissions threatens the availability of fumigants for agricultural use. The objective of this research was to determine the performa...

  18. Reducing CO2 emissions and energy consumption of heat-integrated distillation systems.

    PubMed

    Gadalla, Mamdouh A; Olujic, Zarko; Jansens, Peter J; Jobson, Megan; Smith, Robin

    2005-09-01

    Distillation systems are energy and power intensive processes and contribute significantly to the greenhouse gases emissions (e.g. carbon dioxide). Reducing CO2 emissions is an absolute necessity and expensive challenge to the chemical process industries in orderto meetthe environmental targets as agreed in the Kyoto Protocol. A simple model for the calculation of CO2 emissions from heat-integrated distillation systems is introduced, considering typical process industry utility devices such as boilers, furnaces, and turbines. Furnaces and turbines consume large quantities of fuels to provide electricity and process heats. As a result, they produce considerable amounts of CO2 gas to the atmosphere. Boilers are necessary to supply steam for heating purposes; besides, they are also significant emissions contributors. The model is used in an optimization-based approach to optimize the process conditions of an existing crude oil atmospheric tower in order to reduce its CO2 emissions and energy demands. It is also applied to generate design options to reduce the emissions from a novel internally heat-integrated distillation column (HIDiC). A gas turbine can be integrated with these distillation systems for larger emissions reduction and further energy savings. Results show that existing crude oil installations can save up to 21% in energy and 22% in emissions, when the process conditions are optimized. Additionally, by integrating a gas turbine, the total emissions can be reduced further by 48%. Internal heat-integrated columns can be a good alternative to conventional heat pump and other energy intensive close boiling mixtures separations. Energy savings can reach up to 100% with respect to reboiler heat requirements. Emissions of these configurations are cut down by up to 83%, compared to conventional units, and by 36%, with respect to heat pump alternatives. Importantly, cost savings and more profit are gained in parallel to emissions minimization.

  19. Enhancing soil infiltration reduces gaseous emissions and improves N uptake from applied dairy slurry.

    PubMed

    Bhandral, R; Bittman, S; Kowalenko, G; Buckley, K; Chantigny, M H; Hunt, D E; Bounaix, F; Friesen, A

    2009-01-01

    Rapid infiltration of liquid manure into the soil reduces emissions of ammonia (NH(3)) into the atmosphere. This study was undertaken to assess the effects of two low-cost methods of assisting infiltration of applied dairy slurry on emissions of NH(3), nitrous oxide (N(2)O), and on crop N uptake. The two methods were removing of solids by settling-decantation to make the manure less viscous and mechanically aerating the soil. Ammonia emissions were measured with wind tunnels as percentage of applied total ammoniacal nitrogen (TAN) while emissions of N(2)O were measured with vented chambers. Mechanically aerating the soil before manure application significantly reduced emissions of NH(3) relative to the nonaerated soil in spring (38.6 to 20.3% of applied TAN), summer (41.1 to 26.4% of applied TAN) and fall (27.7 to 13.6% of applied TAN) trials. Decantation of manure had no effect on NH(3) emissions in spring, tended to increase emissions in summer and significantly decreased emissions in fall (30.3 to 11.1% of applied TAN). Combining the two abatement techniques reduced NH(3) emission by 82% in fall, under cool weather conditions typical of manure spreading. The two abatement techniques generally did not significantly affect N(2)O emissions. Uptake of applied N by Italian ryegrass (Lolium multiflorum Lam.) was generally significantly greater with decanted than from whole manure but the effect of aeration was generally small and not significant. The study shows that low cost methods that assist manure infiltration into the soil may be used to greatly reduce ammonia loss without increasing N(2)O emissions, but efficacy of abatement methods is affected by weather conditions.

  20. Reducing the Read Noise of HAWAII-2RG Detector Systems with Improved Reference Sampling and Subtraction (IRS2)

    NASA Technical Reports Server (NTRS)

    Rauscher, Bernard J.; Arendt, Richard G.; Fixsen, D. J.; Lander, Matthew; Lindler, Don; Loose, Markus; Moseley, S. H.; Wilson, Donna V.; Xenophontos, Christos

    2012-01-01

    IRS2 is a Wiener-optimal approach to using all of the reference information that Teledyne's HAWAII-2RG detector arrays provide. Using a new readout pattern, IRS2 regularly interleaves reference pixels with the normal pixels during readout. This differs from conventional clocking, in which the reference pixels are read out infrequently, and only in a few rows and columns around the outside edges of the detector array. During calibration, the data are processed in Fourier space, which is <;:lose to the noise's eigenspace. Using IRS2, we have reduced the read noise of the James Webb Space Telescope Near Infrared Spectrograph by 15% compared to conventional readout. We are attempting to achieve further gains by calibrating out recently recognized non-stationary noise that appears at the frame rate.

  1. Full-scale tests of reflective noise-reducing devices for balconies on high-rise buildings.

    PubMed

    Ishizuka, Takashi; Fujiwara, Kyoji

    2013-08-01

    In the present report, the noise-shielding efficiency of balconies with ceiling-mounted reflectors on the façades of high-rise buildings is examined through full-scale field measurements. The reflectors are designed to reflect direct and diffracted waves incident on the balcony ceiling outside the balcony. Field measurements are conducted to investigate the performance of the reflectors on intermediate floors of a high-rise dwelling adjacent to a railway. The reflectors reduce railway noise by approximately 5 dB, in A-weighted sound pressure level, compared to an ordinary balcony. The noise-shielding efficiency of a balcony equipped with reflectors is greater than that of an absorbing balcony.

  2. Highly Doped Polycrystalline Silicon Microelectrodes Reduce Noise in Neuronal Recordings In Vivo

    PubMed Central

    Saha, Rajarshi; Jackson, Nathan; Patel, Chetan; Muthuswamy, Jit

    2013-01-01

    The aims of this study are to 1) experimentally validate for the first time the nonlinear current-potential characteristics of bulk doped polycrystalline silicon in the small amplitude voltage regimes (0–200 μV) and 2) test if noise amplitudes (0–15 μV) from single neuronal electrical recordings get selectively attenuated in doped polycrystalline silicon microelectrodes due to the above property. In highly doped polycrystalline silicon, bulk resistances of several hundred kilo-ohms were experimentally measured for voltages typical of noise amplitudes and 9–10 kΩ for voltages typical of neural signal amplitudes (>150–200 μV). Acute multiunit measurements and noise measurements were made in n = 6 and n = 8 anesthetized adult rats, respectively, using polycrystalline silicon and tungsten microelectrodes. There was no significant difference in the peak-to-peak amplitudes of action potentials recorded from either microelectrode (p > 0.10). However, noise power in the recordings from tungsten microelectrodes (26.36 ± 10.13 pW) was significantly higher (p < 0.001) than the corresponding value in polycrystalline silicon microelectrodes (7.49 ± 2.66 pW). We conclude that polycrystalline silicon microelectrodes result in selective attenuation of noise power in electrical recordings compared to tungsten microelectrodes. This reduction in noise compared to tungsten microelectrodes is likely due to the exponentially higher bulk resistances offered by highly doped bulk polycrystalline silicon in the range of voltages corresponding to noise in multiunit measurements. PMID:20667815

  3. Reduced Connexin26 in the Mature Cochlea Increases Susceptibility to Noise-Induced Hearing Loss in Mice

    PubMed Central

    Zhou, Xing-Xing; Chen, Sen; Xie, Le; Ji, Yu-Zi; Wu, Xia; Wang, Wen-Wen; Yang, Qi; Yu, Jin-Tao; Sun, Yu; Lin, Xi; Kong, Wei-Jia

    2016-01-01

    Connexin26 (Cx26, encoded by GJB2) mutations are the most common cause of non-syndromic deafness. GJB2 is thought to be involved in noise-induced hearing loss (NIHL). However, the role of Cx26 in NIHL is still obscure. To explore the association between Cx26 and NIHL, we established a Cx26 knockdown (KD) mouse model by conditional knockdown of Cx26 at postnatal day 18 (P18), and then we observed the auditory threshold and morphologic changes in these mice with or without noise exposure. The Cx26 KD mice did not exhibit substantial hearing loss and hair cell degeneration, while the Cx26 KD mice with acoustic trauma experienced higher hearing loss than simple noise exposure siblings and nearly had no recovery. Additionally, extensive outer hair cell loss and more severe destruction of the basal organ of Corti were observed in Cx26 KD mice after noise exposure. These data indicate that reduced Cx26 expression in the mature mouse cochlea may increase susceptibility to noise-induced hearing loss and facilitate the cell degeneration in the organ of Corti. PMID:26927086

  4. Noise-assisted energy transfer from the dilation of the set of one-electron reduced density matrices

    NASA Astrophysics Data System (ADS)

    Chakraborty, Romit; Mazziotti, David A.

    2017-05-01

    Noise-assisted energy transfer can be explained geometrically in terms of the set of one-electron reduced density matrices (1-RDMs) [R. Chakraborty and D. A. Mazziotti, Phys. Rev. A 91, 010101(R) (2015)]. In this paper, we examine the geometric picture of quantum noise for the seven-chromophore Fenna-Matthews-Olson (FMO) complex. Noise expands the feasible set of orbital occupation trajectories to the target state through the violation of the pure-state N-representability conditions on the 1-RDM, known as the generalized Pauli constraints. While the generalized Pauli constraints are not explicitly known for seven-electron systems, we are able to treat a seven-exciton model of the FMO complex through the use of generalized Pauli constraints for p qubits which are known for arbitrary p. In the model, we find that while dephasing noise alone produces a trajectory of ensemble states that neither expands the set of 1-RDMs nor reaches the reaction center, the inclusion of both dephasing and dissipation expands the set of 1-RDMs and exhibits an efficient energy transfer to the reaction center. The degree to which the noise expands the set of 1-RDMs, violating the generalized Pauli constraints, is quantified by the distance of the 1-RDM outside its pure set to the distance of the 1-RDM inside its ensemble set. The geometric picture of energy transfer has applications to general quantum systems in chemistry and physics.

  5. Experimental evidence for the reducibility of multifragment emission probabilities

    SciTech Connect

    Wozniak, G.J.; Tso, K.; Phair, L.

    1995-01-01

    Multifragmentation has been studied for {sup 36}Ar-induced reactions on a {sup 197}Au target at E/A = 80 and 110 MeV and for {sup 129}Xe-induced reactions on several targets ({sup nat}Cu, {sup 89}y, {sup 165}ho, {sup 197}Au) and E/A = 40, 50 and 60 MeV. The probability of emitting n intermediate-mass-fragments is shown to be binomial at each transversal energy and reducible to an elementary binary probability p. For each target and at each bombarding energy, this probability p shows a thermal nature by giving linear Arrhenius plots. For the {sup 129}Xe-induced reactions, a nearly universal linear Arrhenius plot is observed at each bombarding energy, indicating a large degree of target independence.

  6. Reducing CO2-Emission by using Eco-Cements

    NASA Astrophysics Data System (ADS)

    Voit, K.; Bergmeister, K.; Janotka, I.

    2012-04-01

    CO2 concentration in the air is rising constantly. Globally, cement companies are emitting nearly two billion tonnes/year of CO2 (or around 6 to 7 % of the planet's total CO2 emissions) by producing portland cement clinker. At this pace, by 2025 the cement industry will be emitting CO2 at a rate of 3.5 billion tones/year causing enormous environmental damage (Shi et al., 2011; Janotka et al., 2012). At the dawn of the industrial revolution in the mid-eighteenth century the concentration of CO2 was at a level of ca. 280 ppm. 200 years later at the time of World War II the CO2 level had risen to 310 ppm what results in a rate of increase of 0,15 ppm per year for that period (Shi et al., 2011). In November 2011 the CO2 concentration reached a value of 391 ppm (NOAA Earth System Research Laboratory, 2011), a rise of ca. 81 ppm in 66 years and an increased rate of around 1,2 ppm/year respectively. In the same period cement production in tons of cement has multiplied by a factor of ca. 62 (Kelly & Oss, US Geological Survey, 2010). Thus new CO2-saving eco-cement types are gaining in importance. In these cement types the energy-consuming portland cement clinker is partially replaced by latent hydraulic additives such as blast furnace slag, fly ash or zeolite. These hydraulic additives do not need to be fired in the rotary furnace. They ony need to be pulverized to the required grain size and added to the ground portland cement clinker. Hence energy is saved by skipping the engery-consuming firing process, in addition there is no CO2-degassing as there is in the case of lime burning. Therefore a research project between Austria and Slovakia, funded by the EU (Project ENVIZEO), was initiated in 2010. The main goal of this project is to develop new CEM V eco-types of cements and certificate them for common usage. CEM V is a portland clinker saving cement kind that allows the reduction of clinker to a proportion of 40-64% for CEM V/A and 20-39% for CEM V/B respectively by the

  7. Status of Technological Advancements for Reducing Aircraft Gas Turbine Engine Pollutant Emissions

    NASA Technical Reports Server (NTRS)

    Rudey, R. A.

    1975-01-01

    Combustor test rig results indicate that substantial reductions from current emission levels of carbon monoxide (CO), total unburned hydrocarbons (THC), oxides of nitrogen (NOx), and smoke are achievable by employing varying degrees of technological advancements in combustion systems. Minor to moderate modifications to existing conventional combustors produced significant reductions in CO and THC emissions at engine low power (idle/taxi) operating conditions but did not effectively reduce NOx at engine full power (takeoff) operating conditions. Staged combusiton techniques were needed to simultaneously reduce the levels of all the emissions over the entire engine operating range (from idle to takeoff). Emission levels that approached or were below the requirements of the 1979 EPA standards were achieved with the staged combustion systems and in some cases with the minor to moderate modifications to existing conventional combustion systems. Results from research programs indicate that an entire new generation of combustor technology with extremely low emission levels may be possible in the future.

  8. Status review of NASA programs for reducing aircraft gas turbine engine emissions

    NASA Technical Reports Server (NTRS)

    Rudey, R. A.

    1976-01-01

    Programs initiated by NASA to develop and demonstrate low emission advanced technology combustors for reducing aircraft gas turbine engine pollution are reviewed. Program goals are consistent with urban emission level requirements as specified by the U. S. Environmental Protection Agency and with upper atmosphere cruise emission levels as recommended by the U. S. Climatic Impact Assessment Program and National Research Council. Preliminary tests of advanced technology combustors indicate that significant reductions in all major pollutant emissions should be attainable in present generation aircraft gas turbine engines without adverse effects on fuel consumption. Preliminary test results from fundamental studies indicate that extremely low emission combustion systems may be possible for future generation jet aircraft. The emission reduction techniques currently being evaluated in these programs are described along with the results and a qualitative assessment of development difficulty.

  9. Selective attention reduces physiological noise in the external ear canals of humans. I: Auditory attention

    PubMed Central

    Walsh, Kyle P.; Pasanen, Edward G.; McFadden, Dennis

    2014-01-01

    In this study, a nonlinear version of the stimulus-frequency OAE (SFOAE), called the nSFOAE, was used to measure cochlear responses from human subjects while they simultaneously performed behavioral tasks requiring, or not requiring, selective auditory attention. Appended to each stimulus presentation, and included in the calculation of each nSFOAE response, was a 30-ms silent period that was used to estimate the level of the inherent physiological noise in the ear canals of our subjects during each behavioral condition. Physiological-noise magnitudes were higher (noisier) for all subjects in the inattention task, and lower (quieter) in the selective auditory-attention tasks. These noise measures initially were made at the frequency of our nSFOAE probe tone (4.0 kHz), but the same attention effects also were observed across a wide range of frequencies. We attribute the observed differences in physiological-noise magnitudes between the inattention and attention conditions to different levels of efferent activation associated with the differing attentional demands of the behavioral tasks. One hypothesis is that when the attentional demand is relatively great, efferent activation is relatively high, and a decrease in the gain of the cochlear amplifier leads to lower-amplitude cochlear activity, and thus a smaller measure of noise from the ear. PMID:24732069

  10. The a priori SDR Estimation Techniques with Reduced Speech Distortion for Acoustic Echo and Noise Suppression

    NASA Astrophysics Data System (ADS)

    Thoonsaengngam, Rattapol; Tangsangiumvisai, Nisachon

    This paper proposes an enhanced method for estimating the a priori Signal-to-Disturbance Ratio (SDR) to be employed in the Acoustic Echo and Noise Suppression (AENS) system for full-duplex hands-free communications. The proposed a priori SDR estimation technique is modified based upon the Two-Step Noise Reduction (TSNR) algorithm to suppress the background noise while preserving speech spectral components. In addition, a practical approach to determine accurately the Echo Spectrum Variance (ESV) is presented based upon the linear relationship assumption between the power spectrum of far-end speech and acoustic echo signals. The ESV estimation technique is then employed to alleviate the acoustic echo problem. The performance of the AENS system that employs these two proposed estimation techniques is evaluated through the Echo Attenuation (EA), Noise Attenuation (NA), and two speech distortion measures. Simulation results based upon real speech signals guarantee that our improved AENS system is able to mitigate efficiently the problem of acoustic echo and background noise, while preserving the speech quality and speech intelligibility.

  11. Exposure smart hearing protector for reducing noise-induced hearing loss

    NASA Astrophysics Data System (ADS)

    Nykaza, Ed; Frank, Tom

    2003-10-01

    The Exposure Smart Hearing Protector (ESHP) is a new device that can be used for measuring noise exposure levels (NELs) and the prevention of noise induced hearing loss (NIHL). The ESHP consists of two microphones, located in a right and left earplug, that are connected to a dosimeter. In practice, the user wears the ESHP. When the noise level exceeds a safe dose a warning light comes on. The user then inserts the earplugs. If the earplugs are correctly inserted and the noise level in the user's earcanal is below a safe level the warning lights go off. As a result, the ESHP measures the user's total daily noise exposure (unprotected and protected). To increase the efficiency of using the ESHP for preventing NIHL, the user downloads the information stored in the ESHP via a scanner into user friendly-software. The software can be used not only to record a user's daily NELs, but more importantly to determine if the user needs intervention because the NELs exceed a safe level. The purpose of this poster session is to demonstrate the ESHP and software, and to report the results of a pilot study. [Work supported by NIOSH/CDC Grant No. U60/CCU 315855.

  12. The use of cowl camber and taper to reduce rotor/stator interaction noise

    NASA Technical Reports Server (NTRS)

    Martinez, R.

    1995-01-01

    The project had two specific technical objectives: (1) to develop a realistic three-dimensional model of tonal noise due to rotor/stator interaction, as the input field for predictions of diffraction and dissipation by a lined cowl; and (2) to determine whether the generator curve of that cowl, or duct, could be 'steered' to yield substantially lower values of propulsor noise along the engine's fore and aft open sectors. The more general and important aim of their research is to provide the commercial aircraft industry with a useful predictive tool to help it meet its noise-reduction goals. The work has produced a tractable and yet realistic model of rotor/stator interaction noise. The blades in the fan stage are radially divergent, twisted, and of realistically wide chords to match the high frequencies and speeds of the sound-production process. The resulting three-dimensional acoustic nearfield insonifies the interior wall of the diffracting cowl, whose shape, incidentally, does not affect fore or aft noise significantly (but other factors do).

  13. Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace.

    PubMed

    Keane, Michael; Siert, Arlen; Stone, Samuel; Chen, Bean T

    2016-01-01

    Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr(6+)). Elemental manganese, nickel, chromium, iron emissions per unit length of weld, and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered, and analyzed by inductively coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr(6+). GMAW processes used were Surface Tension Transfer, Regulated Metal Deposition, Cold Metal Transfer, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr(6+) ranged from 50-7800 µg/min, and Cr(6+) generation rates per g electrode ranged from 1-270 µg/g. Elemental Cr generation rates spanned 13-330 µg/g. Manganese emission rates ranged from 50-300 µg/g. Nickel emission rates ranged from 4-140 µg/g. Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as five times the cost of a typical SMAW welding machine. The results show that all of the GMAW processes in this

  14. Pilot study to reduce emissions, improve health, and offset BC emissions through the distribution of improved cook stoves in Nepal

    NASA Astrophysics Data System (ADS)

    Banmali Pradhan, B.; Panday, A. K.; Surapipith, V.

    2013-12-01

    In most developing countries, wood and other biomass fuels are still the primary source of energy for the majority of the people, particularly the poor. It is estimated that cook stoves account for approximately 20% of global black carbon emissions. In Nepal 87% of energy is supplied from traditional biomass and 75% of households still depend on biomass as a cooking fuel. The substitution of traditional cook stoves with improved cook stoves provides an important way to reduce black carbon emissions. In 2013 the International Centre for Integrated Mountain Development (ICIMOD) has commenced a pilot study that both examines ways to effectively disseminate improved cookstoves across remote rural mountain regions, and also quantifies the resulting changes in emissions, air quality and health. The selected study area is in Bajrabarahi Village in Makawanpur district, to the southwest of Kathmandu. The study area consists of around 1600 households, which are divided into control groups and groups where the cook stove intervention is taking place. The study complements the ';Clean Cooking energy solution for all by 2017' announced by the Government of Nepal recently, and will provide insights to the government on ways to effectively reduce black carbon emissions from cook stoves. To make the study robust and sustainable, local women's group and a local medical institution are involved in the project right from the conceptualization stage. The study region has been chosen in part because the medical school Patan Academy of Health Sciences (PAHS) has already started a long term health assessment in the region, and has built up considerable local contacts. The local women's group is working on the modality of cook stove distribution through micro credit programmes in the village. We will distribute the best available manufactured, fan-assisted cook stoves that are expected to reduce BC emissions the most. Health assessments, emissions estimates, as well as measurements of

  15. Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace

    PubMed Central

    Keane, Michael; Siert, Arlen; Stone, Samuel; Chen, Bean T.

    2016-01-01

    Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr6+). Elemental manganese, nickel, chromium, iron emissions per unit length of weld and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered and analyzed by inductively-coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr6+. GMAW processes used were Surface Tension Transfer™, Regulated Metal Deposition™, Cold Metal Transfer™, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr6+ ranged from 50 to 7800 μg/min, and Cr6+ generation rates per g electrode ranged from 1 to 270μg/g. Elemental Cr generation rates spanned 13 to 330μg/g. Manganese emission rates ranged from 50 to 300μg/g. Nickel emission rates ranged from 4 to140 μg/g. Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as 5 times the cost of a typical SMAW welding machine. The results show that all of the GMAW processes

  16. Low-noise cold-field emission current obtained between two opposed carbon cone nanotips during in situ transmission electron microscope biasing

    SciTech Connect

    Knoop, L. de; Gatel, C.; Houdellier, F.; Monthioux, M.; Masseboeuf, A.; Snoeck, E.; Hÿtch, M. J.

    2015-06-29

    A dedicated transmission electron microscope sample holder has been used to study in situ the cold-field emission process of carbon cone nanotips (CCnTs). We show that when using a CCnT instead of a Au plate-anode, the standard deviation of the emission current noise can be decreased from the 10 nA range to the 1 nA range under vacuum conditions of 10{sup −5 }Pa. This shows the strong influence of the anode on the cold-field emission current noise.

  17. Effect of water seal on reducing 1,3-dichloropropene emissions from different soil textures.

    PubMed

    McDonald, Jason A; Gao, Suduan; Qin, Ruijun; Hanson, Bradley D; Trout, Thomas J; Wang, Dong

    2009-01-01

    Soil physical conditions can affect diffusion, environmental fate, and efficacy of fumigants in soil disinfestation treatments. Water seals (applying water using sprinklers to soil following fumigation) can effectively reduce fumigant emissions from sandy loam soils. Soil column studies compared the effectiveness of water seals in reducing cis-1,3-dichloropropene (1,3-D) emissions from three different textured soils (loamy sand, sandy loam, and loam). Treatments included an untreated control, an initial water seal (9 mm water applied immediately before fumigant injection), and intermittent water seals (initial 9 mm water seal followed by 3 mm at 12 and 24 h). For the loamy sand, instead of the initial water seal treatment, a reduced-amount intermittent water seal (initial 3 mm water followed by 1 mm at 12 and 24 h) treatment was tested. Overall emission loss of 1,3-D from the control over 2 wk was 56% for the loamy sand, 51% for the sandy loam, and 43% for the loam. The initial water seal reduced total 1,3-D emissions to 46% in the sandy loam and 31% in the loam. The intermittent water seals reduced emission loss to 26% for the loamy sand, 41% for the sandy loam, and 21% for the loam. The reduced-amount intermittent water seal for loamy sand had little effect. Low emission loss was associated with high surface soil water content. None of the water applications reduced gaseous fumigant concentrations. Results indicate that water seal techniques may be able to effectively reduce emissions for different soil textures without reducing fumigant concentration in the soil.

  18. Technological progress in reducing CFC (chlorofluorocarbon) and halon emissions

    SciTech Connect

    Smith, N.D.; Shapiro, P.S.

    1989-04-01

    This paper discusses EPA's development of a technological program to implement in the U.S. the Montreal Protocol on Substances that Deplete the Ozone Layer. EPA's Office of Air and Radiation (OAR) has the lead for developing the technical and economic goals of the program, and EPA's Office of Research and Development (ORD) has the lead in providing technical support to meet the goals, including both short-term projects and long-term research. EPA's strategy is to target the halon and high chlorofluorocarbon (CFC)-using industries or industry subgroups to identify opportunities to reduce CFC and halon usage and find alternatives. When such opportunities are found, cooperative industry/government groups are formed to identify and solve the problems that impede transition away from CFC and halon usage. Other groups (including academic, non-profit research institutes, other government agencies, and foreign individuals or groups) are invited to join in the effort if they have a special expertise or interest. Identifying the high-use industry sectors and subsectors is not difficult; however, identifying appropriate industries, individuals, and groups who are willing to influence industry usage of CFCs is not easy.

  19. Institute a modest carbon tax to reduce carbon emissions, finance clean energy technology development, cut taxes, and reduce the deficit

    SciTech Connect

    Muro, Mark; Rothwell, Jonathan

    2012-11-15

    The nation should institute a modest carbon tax in order to help clean up the economy and stabilize the nation’s finances. Specifically, Congress and the president should implement a $20 per ton, steadily increasing carbon excise fee that would discourage carbon dioxide emissions while shifting taxation onto pollution, financing energy efficiency (EE) and clean technology development, and providing opportunities to cut taxes or reduce the deficit. The net effect of these policies would be to curb harmful carbon emissions, improve the nation’s balance sheet, and stimulate job-creation and economic renewal.

  20. A research program to reduce interior noise in general aviation airplanes

    NASA Technical Reports Server (NTRS)

    Peschier, T. D.; Andrews, D.; Henderson, T.

    1977-01-01

    The relevance of KU-FRL test results in predicting (theoretically or semi-empirically) interior noise levels in general aviation aircraft was studied. As a result of this study, it was decided to make a few additions to the program. These additions are: (1) to use three (instead of two) noise sources in the plane wave tube to evaluate the influence of excitation spectrum on panel response, (2) to use theoretical and experimental data obtained in the course of the project to develop more efficient noise reduction materials (or procedures to apply these), or to develop guidelines for the design of such materials for procedures, and (3) to use nonstructural materials in the collection of specimens to be tested in the KU-FRL plane wave tube.