WorldWideScience

Sample records for submarine radiated noise

  1. Experimental research on the double-peak characteristic of underwater radiated noise in the near field on top of a submarine

    Science.gov (United States)

    Liu, Ning; Wang, Sande; Guo, Tao; Li, Xiyou; Yu, Ziyang

    2011-06-01

    The double-peak characteristic of underwater radiated noise in the near field on top of the target submarine was analyzed in depth on the basis of submarine test data on the sea. The contribution of three major noise sources to the radiated noise of a submarine were compared and analyzed, and emphasis was put on the original source, production mechanism, and their correlative characteristics. On the basis of analysis on underwater tracking and pass through characteristics of the target submarine, the double-peak phenomenon was reasonably interpreted. Furthermore, the correctness of the theoretical interpretation was verified adequately in real submarine tests. The double-peak phenomenon indicates that the space distributing character on submarine radiated noise are both asymmetrical with time and space, whereas that is provided with directivity. Studying the double-peak phenomenon in depth has important reference value and meaning in engineering practice for understanding the underwater radiated noise field of submarines.

  2. Scattering effect of submarine hull on propeller non-cavitation noise

    Science.gov (United States)

    Wei, Yingsan; Shen, Yang; Jin, Shuanbao; Hu, Pengfei; Lan, Rensheng; Zhuang, Shuangjiang; Liu, Dezhi

    2016-05-01

    This paper investigates the non-cavitation noise caused by propeller running in the wake of submarine with the consideration of scattering effect caused by submarine's hull. The computation fluid dynamics (CFD) and acoustic analogy method are adopted to predict fluctuating pressure of propeller's blade and its underwater noise radiation in time domain, respectively. An effective iteration method which is derived in the time domain from the Helmholtz integral equation is used to solve multi-frequency waves scattering due to obstacles. Moreover, to minimize time interpolation caused numerical errors, the pressure and its derivative at the sound emission time is obtained by summation of Fourier series. It is noted that the time averaging algorithm is used to achieve a convergent result if the solution oscillated in the iteration process. Meanwhile, the developed iteration method is verified and applied to predict propeller noise scattered from submarine's hull. In accordance with analysis results, it is summarized that (1) the scattering effect of hull on pressure distribution pattern especially at the frequency higher than blade passing frequency (BPF) is proved according to the contour maps of sound pressure distribution of submarine's hull and typical detecting planes. (2) The scattering effect of the hull on the total pressure is observable in noise frequency spectrum of field points, where the maximum increment is up to 3 dB at BPF, 12.5 dB at 2BPF and 20.2 dB at 3BPF. (3) The pressure scattered from hull is negligible in near-field of propeller, since the scattering effect surrounding analyzed location of propeller on submarine's stern is significantly different from the surface ship. This work shows the importance of submarine's scattering effect in evaluating the propeller non-cavitation noise.

  3. Effects of symmetrical foundation on sound radiation from a submarine hull structure.

    Science.gov (United States)

    Li, Chenyang; Su, Jinpeng; Wang, Jian; Hua, Hongxing

    2015-11-01

    The effects of a passive noise control method for suppressing sound radiation from a submarine hull structure are investigated. The control method is realized by symmetrizing the foundation about the horizontal plane. The coupled finite element method and boundary element method are adopted to compute the acoustic characteristics of the submerged hull. From the numerical results, the symmetrical foundation has advantages in sound radiation reduction when the hull is subjected to the axial load, but has little influences in the vertical and transverse load cases. Using the modal decomposition technique, the contributions of each individual mode to the sound radiation are analyzed to reveal the mechanism of the control method.

  4. Australia’s Submarine Design Capabilities and Capacities: Challenges and Options for the Future Submarine

    Science.gov (United States)

    2011-01-01

    General Dynamics Electric Boat Corporation EMC electromagnetic compatibility EMF electromagnetic field EMI electromagnetic interference EPCM engineering...to-diagnose flow-induced radiated noise Own-sensor performance degradation Note: Risks can be reduced for given designs using scale models...Acoustic analysis Addresses the total radiated noise signature of submarine designs Radiated noise that an enemy might detect Self-noise that that

  5. [Effect of noise in submarine compartment on signal discrimination and arithmetic performance].

    Science.gov (United States)

    Hu, Z; Liang, Z; Shi, X; Tang, Z

    1997-06-01

    To study the effects of noise level in submarine compartment on signal discrimination and arithmetic performance, experiments were carried out on 13 subjects. The results showed that as noise level raised from moderate (73 dBA) to higher levels (85-92 dBA), work efficiency showed a progressive decrease, but when noise level reached 96 dBA the decrease in efficiency reached a steady state. The results indicated that impairment of efficiency apparently occurred at a level of 85 dBA and that the interference effect of noise was more pronounced on task performance with mental strain.

  6. Influence of stiffness constant of stern bearing on vibration and acoustic radiation of whole submarine

    Directory of Open Access Journals (Sweden)

    WANG Lucai

    2018-02-01

    Full Text Available [Objectives] This paper studies the influence of the stiffness constant of a stern bearing on the vibration and acoustic radiation of a whole submarine.[Methods] Based on the form of SUBOFF, a whole submarine model is established in which the structures of the propeller and shaft are first formed in solid elements. Through calculating and comparing the structural vibration and acoustic radiation driven by a vertically excited force, the influence of the elastic coefficient of the stern bearing on the vibroacoustic of the overall submarine structure is mainly considered. [Results] It is demonstrated that the reduction of the elastic coefficient of the stern bearing leads to the convergence of structural vibration and acoustic radiation to the second order overall bending modal frequency, and the frequency gradually becomes lower, which can benefit the vibroacoustic reduction of submarines at frequencies higher than the second order overall bending modal frequency. [Conclusions] These results provide a reference for the acoustic design of submarine structures.

  7. Underwater radiated noise from modern commercial ships.

    Science.gov (United States)

    McKenna, Megan F; Ross, Donald; Wiggins, Sean M; Hildebrand, John A

    2012-01-01

    Underwater radiated noise measurements for seven types of modern commercial ships during normal operating conditions are presented. Calibrated acoustic data (Stern aspect noise levels are 5 to 10 dB higher than bow aspect noise levels. Collectively, these results emphasize the importance of including modern ship-types in quantifying shipping noise for predictive models of global, regional, and local marine environments. © 2012 Acoustical Society of America.

  8. Investigation of weldments in Victoria-class submarine pressure-hull using magnetic flux leakage and Barkhausen noise

    Science.gov (United States)

    Samimi, A. A.; Babbar, V.; Krause, T. W.; Clapham, L.

    2014-02-01

    Evaluation of the stress state within submarine hulls can contribute to risk assessments, which provide assurance that in-service induced stresses will not adversely affect the service life of the naval structure. The purpose of this study was to evaluate the feasibility of using magnetic NDE techniques for identification of stresses associated with weldments in two original pressure hulls of Canada's Victoria class submarines. Magnetic Flux Leakage (MFL) and flux-controlled Barkhausen Noise measurements were investigated for identification of patch boundaries and welds in two sections of Victoria-class submarine-hull steel. While MFL showed clear demarcation of weld boundaries, Barkhausen measurements did not provide sufficiently clear response to identify these features in submarine hull samples. For a better understanding of Barkhausen response, uniaxial tensile stress was investigated on separate samples of submarine steel. A nonlinear dependence of Barkhausen response was observed, with a weaker sensitivity to tensile stresses below 200 MPa. This behavior, combined with the presence of substantial surface compressive stresses, was used to explain the observed insensitivity of Barkhausen measurements to the presence of welds.

  9. Development and experimental verification of a robust active noise control system for a diesel engine in submarines

    Science.gov (United States)

    Sachau, D.; Jukkert, S.; Hövelmann, N.

    2016-08-01

    This paper presents the development and experimental validation of an ANC (active noise control)-system designed for a particular application in the exhaust line of a submarine. Thereby, tonal components of the exhaust noise in the frequency band from 75 Hz to 120 Hz are reduced by more than 30 dB. The ANC-system is based on the feedforward leaky FxLMS-algorithm. The observability of the sound pressure in standing wave field is ensured by using two error microphones. The noninvasive online plant identification method is used to increase the robustness of the controller. Online plant identification is extended by a time-varying convergence gain to improve the performance in the presence of slight error in the frequency of the reference signal.

  10. Anti noise system and method using broadband radiation modes

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    2002-01-01

    Anti noise system and method, in particular for suppressing sound radiated from a structure, using a formulation of the most efficiently radiating vibration patterns of a vibrating body, the radiation modes, in the time domain. The radiation modes can be used to arrive at efficient weighting schemes

  11. Discharge modulation noise in He---Ne laser radiation

    NARCIS (Netherlands)

    Bolwijn, P.T.

    1967-01-01

    Discharge modulation noise in He---Ne laser radiation is considered theoretically, including explicitly the laser oscillator properties. Experiments reported previously by us and other authors are in agreement with our analysis.

  12. The Effects of Crosswind Flight on Rotor Harmonic Noise Radiation

    Science.gov (United States)

    Greenwood, Eric; Sim, Ben W.

    2013-01-01

    In order to develop recommendations for procedures for helicopter source noise characterization, the effects of crosswinds on main rotor harmonic noise radiation are assessed using a model of the Bell 430 helicopter. Crosswinds are found to have a significant effect on Blade-Vortex Interaction (BVI) noise radiation when the helicopter is trimmed with the fuselage oriented along the inertial flight path. However, the magnitude of BVI noise remains unchanged when the pilot orients the fuselage along the aerodynamic velocity vector, crabbing for zero aerodynamic sideslip. The effects of wind gradients on BVI noise are also investigated and found to be smaller in the crosswind direction than in the headwind direction. The effects of crosswinds on lower harmonic noise sources at higher flight speeds are also assessed. In all cases, the directivity of radiated noise is somewhat changed by the crosswind. The model predictions agree well with flight test data for the Bell 430 helicopter captured under various wind conditions. The results of this investigation would suggest that flight paths for future acoustic flight testing are best aligned across the prevailing wind direction to minimize the effects of winds on noise measurements when wind cannot otherwise be avoided.

  13. Submarine explosive activity and ocean noise generation at Monowai Volcano, Kermadec Arc: constraints from hydroacoustic T-waves

    OpenAIRE

    Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony

    2016-01-01

    Submarine volcanic activity is difficult to detect, because eruptions at depth are strongly attenuated by seawater. With increasing depth the ambient water pressure increases and limits the expansion of gas and steam such that volcanic eruptions tend to be less violent and less explosive with depth. Furthermore, the thermal conductivity and heat capacity of water causes rapid cooling of ejected products and hence erupted magma cools much more quickly than during subaerial eruptions. Therefore...

  14. Noise and vibration analysis for automotive radiator cooling fan

    Science.gov (United States)

    Razak, N. F. D.; Sani, M. S. M.; Azmi, W. H.; Zhang, B.

    2017-10-01

    This paper aims to analyse the noise and vibration of the automotive radiator specifically focused on its cooling fan for different fan conditions and different coolants used namely Ethylene Glycol (EG) water-based and Titanium Oxide (TiO2) nanofluid. Noise source identification is carried out by utilizing the sound intensity mapping method while an accelerometer is used to measure the vibration results. Both of these experiments are conducted when the fan was both in static and working conditions. The maximum cooling fan speed for the working fan detected by a tachometer for EG water-based is 1990 rpm while TiO2 nanofluid is 2030 rpm. The difference in speed is due to the different physical properties such viscosity of each coolant has where TiO2 nanofluid has lower viscosity than EG water-based. The maximum sound power level produced by EG water-based is 53.73 dB while TiO2 nanofluid is 101.94 dB. Meanwhile, the vibration frequencies of EG water-based are higher than TiO2 nanofluid. The noise level increases with the cooling fan speed but decreases with the vibration frequency. Apart from studying the noise and vibration of the automotive radiator, this research also analysed the potential application using nanofluid due to its great properties according to its major use in the heat transfer enhancement. As a conclusion, nanofluid as a radiator coolant could improve heat transfer rate, and could also reduce the presence of vibration in the automotive cooling system.

  15. Numerical study of jet noise radiated by turbulent coherent structures

    Energy Technology Data Exchange (ETDEWEB)

    Bastin, F.

    1995-08-01

    a numerical approach of jet mixing noise prediction is presented, based on the assumption that the radiated sound field is essentially due to large-scale coherent turbulent structures. A semi-deterministic turbulence modelling is used to obtain the flow coherent fluctuations. This model is derived from the k-{epsilon} model and validated on the 2-D compressible shear layer case. Three plane jets at Mach 0.5, 1.33 and 2 are calculated. The semi-deterministic modelling yields a realistic unsteady representation of plane jets but not appropriate for axisymmetric jet computations. Lighthill`s analogy is used to estimate the noise radiated by the flow. Three integral formulations of the theory are compared and the most suitable one is expressed in space-time Fourier space. This formulation is associated to a geometrical interpretation of acoustic computations in (k, {omega}) plane. The only contribution of coherent structures cannot account for the high-frequency radiation of a subsonic jet and thus, the initial assumption is not verified in the subsonic range. The interpretation of Lighthill`s analogy in (k, {omega}) plane allows to conclude that the missing high-frequency components are due to the inner structure of the coherent motion. For supersonic jets, full acoustic spectra are obtained, at least in the forward arc where the dominant radiation is emitted. For the fastest jet (M = 2), no Mach waves are observed, which may be explained by a ratio of the structures convection velocity to the jet exit velocity lower in plane than in circular jets. This point is confirmed by instability theory calculations. Large eddy simulations (LES) were performed for subsonic jets. Data obtained in the plane jet case show that this technique allows only a slight improvement of acoustic results. To obtain a satisfactory high-frequency radiation, very fine grids should be considered, and the 2-D approximation could not be justified anymore. (Abstract Truncated)

  16. Josephson radiation and shot noise of a semiconductor nanowire junction

    Science.gov (United States)

    van Woerkom, David J.; Proutski, Alex; van Gulik, Ruben J. J.; Kriváchy, Tamás; Car, Diana; Plissard, Sébastian R.; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.; Geresdi, Attila

    2017-09-01

    We measured the Josephson radiation emitted by an InSb semiconductor nanowire junction utilizing photon-assisted quasiparticle tunneling in an ac-coupled superconducting tunnel junction. We quantify the action of the local microwave environment by evaluating the frequency dependence of the inelastic Cooper-pair tunneling of the nanowire junction and find the zero-frequency impedance Z (0 )=492 Ω with a cutoff frequency of f0=33.1 GHz . We extract a circuit coupling efficiency of η ≈0.1 and a detector quantum efficiency approaching unity in the high-frequency limit. In addition to the Josephson radiation, we identify a shot noise contribution with a Fano factor F ≈1 , consistently with the presence of single electron states in the nanowire channel.

  17. Investigation of the Noise Radiation from Heated Supersonic Jets

    Science.gov (United States)

    Mora Sanchez, Pablo A.

    This work focuses in the investigation of crackle and Mach wave radiation in heated supersonic jets. The skewness and kurtosis of the acoustic pressure signal and its time derivative were adopted as metrics for identifying crackling jets and quantifying levels of crackle. Cold and heated jets from supersonic nozzles with different geometric parameters and scales are analyzed to draw conclusions on noise sources and propagation. In order to complement the investigation, results are also presented for the mixing noise, broadband shock-associated noise and screech. Chapter 4 focuses on the impact of jet operating condition on the skewness and kurtosis levels of a jet issuing from a converging-diverging conical nozzle, with a 1.5 design Mach number. An increase in convective Mach number, achieved by increasing jet temperature, proved to be related to elevated values of OASPL, skewness, and kurtosis, in both the near and far fields. Intense levels of the dP/dt high-order statistics appear to be generated at different locations in the shear layer of the jet and strengthen away from the jet by non-linear propagation effects. Chapter 5 studies how adding chevrons to a converging-diverging nozzle impacts Mach wave radiation and crackle. The chevrons decreased OASPL in the downstream angles but increased the broadband shock-associated noise. Pressure skewness, dP/dt skewness and kurtosis were all reduced by the chevrons in the near field and far field, and thus they effectively mitigated crackle and Mach wave radiation; however, chevrons showed no evidence of changing the convective Mach number. The evolution of noise signals was analyzed in the near-field to the far-field to identify the strengthening of skewness through nonlinear propagation effects. Chapter 6 investigates a jet exhausting over a plate at different stand-off distances, to simulate jets exhausting over airframe surfaces and jet-ground interaction during take-off and landing operations. Far-field acoustics

  18. Submarine explosive activity and ocean noise generation at Monowai Volcano, Kermadec Arc: constraints from hydroacoustic T-waves

    Science.gov (United States)

    Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony

    2016-04-01

    Submarine volcanic activity is difficult to detect, because eruptions at depth are strongly attenuated by seawater. With increasing depth the ambient water pressure increases and limits the expansion of gas and steam such that volcanic eruptions tend to be less violent and less explosive with depth. Furthermore, the thermal conductivity and heat capacity of water causes rapid cooling of ejected products and hence erupted magma cools much more quickly than during subaerial eruptions. Therefore, reports on submarine volcanism are restricted to those sites where erupted products - like the presence of pumice rafts, gas bubbling on the sea surface, and local seawater colour changes - reach the sea surface. However, eruptions cause sound waves that travel over far distances through the Sound-Fixing-And-Ranging (SOFAR) channel, so called T-waves. Seismic networks in French Polynesia recorded T-waves since the 1980's that originated at Monowai Volcano, Kermadec Arc, and were attributed to episodic growth and collapse events. Repeated swath-mapping campaigns conducted between 1998 and 2011 confirm that Monowai volcano is a highly dynamic volcano. In July of 2007 a network of ocean-bottom-seismometers (OBS) and hydrophones was deployed and recovered at the end of January 2008. The instruments were located just to the east of Monowai between latitude 25°45'S and 27°30'S. The 23 OBS were placed over the fore-arc and on the incoming subducting plate to obtain local seismicity associated with plate bending and coupling of the subduction megathrust. However, we recognized additional non-seismic sleuths in the recordings. Events were best seen in 1 Hz high-pass filtered hydrophone records and were identified as T-waves. The term T-wave is generally used for waves travelling through the SOFAR channel over large distances. In our case, however, they were also detected on station down to ~8000 m, suggesting that waves on the sea-bed station were direct waves caused by explosive

  19. Cavity optomechanics with micromirrors: Measuring and reducing radiation pressure noise with bright squeezed light

    Science.gov (United States)

    Cripe, Jonathan; Singh, Robinjeet; Yap, Min Jet; Cole, Garrett; Corbitt, Thomas; LIGO Collaboration

    On September 14, 2015, LIGO made the first direct detection of gravitational waves. Advanced LIGO is predicted to be limited by quantum noise at intermediate and high frequencies when it reaches design sensitivity in the next couple years. The quantum noise, including radiation pressure noise at intermediate frequencies, will need to be reduced in order to increase the sensitivity of future gravitational wave interferometers. We report recent progress towards measuring quantum radiation pressure noise in an optomechanical cavity and the reduction of radiation pressure noise using bright squeezed light. The low noise, microfabricated mechanical oscillator also allows for direct broadband thermal noise measurements which test thermal noise models and damping mechanisms and serves as a test bed for the application of crystalline coatings in future gravitational wave detectors. These techniques may be applicable to an upgrade of Advanced LIGO or the next generation of gravitational wave detectors. NSF Grant PHY-1150531.

  20. Submarine hydrodynamics

    CERN Document Server

    Renilson, Martin

    2015-01-01

    This book adopts a practical approach and presents recent research together with applications in real submarine design and operation. Topics covered include hydrostatics, manoeuvring, resistance and propulsion of submarines. The author briefly reviews basic concepts in ship hydrodynamics and goes on to show how they are applied to submarines, including a look at the use of physical model experiments. The issues associated with manoeuvring in both the horizontal and vertical planes are explained, and readers will discover suggested criteria for stability, along with rudder and hydroplane effectiveness. The book includes a section on appendage design which includes information on sail design, different arrangements of bow planes and alternative stern configurations. Other themes explored in this book include hydro-acoustic performance, the components of resistance and the effect of hull shape. Readers will value the author’s applied experience as well as the empirical expressions that are presented for use a...

  1. Box model of radionuclide dispersion and radiation risk estimation for population in case of radioactivity release from nuclear submarine {number_sign}601 dumped in the Kara Sea

    Energy Technology Data Exchange (ETDEWEB)

    Yefimov, E.I.; Pankratov, D.V.; Ignatiev, S.V. [Inst. of Physics and Power Engineering, Obninsk (Russian Federation)

    1997-12-31

    When ships with nuclear reactors or nuclear materials aboard suffer shipwreck or in the case of burial or dumping of radioactive wastes, atmospheric fallout, etc., radionuclides may be released and spread in the sea, contaminating the sea water and the sea bottom. When a nuclear submarine (NS) is dumped this spread of activity may occur due to gradual core destruction by corrosion over many years. The objective of this paper is to develop a mathematical model of radionuclide dispersion and to assess the population dose and radiation risk for radionuclide release from the NS No. 601, with Pb-Bi coolant that was dumped in the Kara Sea.

  2. Aspects of Propeller Developements for a Submarine

    DEFF Research Database (Denmark)

    Andersen, Poul; kappel, Jens Julius; Spangenberg, Eugen

    2009-01-01

    Design and development of propellers for submarines are in some ways different from propellers for surface vessels. The most important demand is low acoustic signature that has priority over propeller efficiency, and the submarine propeller must be optimized with respect to acoustics rather than...... efficiency. Moreover the operating conditions of a submarine propeller are quite different. These aspects are discussed as well as the weighing of the various propeller parameters against the design objectives. The noise generated by the propeller can be characterized as thrust noise due to the inhomogeneous...... wake field of the submarine, trailing-edge noise and noise caused by turbulence in the inflow. The items discussed are demonstrated in a case study where a propeller of the Kappel type was developed. Three stages of the development are presented, including a design of an 8-bladed propeller where...

  3. Living Organisms Coupling to Electromagnetic Radiation Below Thermal Noise

    Science.gov (United States)

    Stolc, Viktor; Freund, Friedemann

    2013-04-01

    Ultralow frequency (ULF) and extremely low frequency (ELF) electromagnetic (EM) radiation is part of the natural environment. Prior to major earthquakes the local ULF and global ELF radiation field is often markedly perturbed. This has detrimental effects on living organisms. We are studying the mechanism of these effects on the biochemical, cellular and organismal levels. The transfer of electrons along the Electron Transfer Chain (ETC) controls the universal reduction-oxidation reactions that are essential for fundamental biochemical processes in living cells. In order for these processes to work properly, the ETC has to maintain some form of synchronization, or coherence with all biochemical reactions in the living cells, including energy production, RNA transcription, and DNA replication. As a consequence of this synchronization, harmful chemical conflict between the reductive and the oxidative partial reactions can be minimized or avoided. At the same time we note that the synchronization allows for a transfer of energy, coherent or interfering, via coupling to the natural ambient EM field. Extremely weak high frequency EM fields, well below the thermal noise level, tuned in frequency to the electron spins of certain steps in the ETC, have already been shown to cause aberrant cell growth and disorientation among plants and animals with respect to the magnetic and gravity vectors. We investigate EM fields over a much wider frequency range, including ULF known to be generated deep in the Earth prior to major earthquakes locally, and ELF known to be fed by lightning discharges, traveling around the globe in the cavity formed between the Earth's surface and the ionosphere. This ULF/ELF radiation can control the timing of the biochemical redox cycle and thereby have a universal effect on physiology of organisms. The timing can even have a detrimental influence, via increased oxidative damage, on the DNA replication, which controls heredity.

  4. Active noise canceling system for mechanically cooled germanium radiation detectors

    Science.gov (United States)

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  5. The Effects of Ambient Conditions on Helicopter Harmonic Noise Radiation: Theory and Experiment

    Science.gov (United States)

    Greenwood, Eric; Sim, Ben W.; Boyd, D. Douglas, Jr.

    2016-01-01

    The effects of ambient atmospheric conditions, air temperature and density, on rotor harmonic noise radiation are characterized using theoretical models and experimental measurements of helicopter noise collected at three different test sites at elevations ranging from sea level to 7000 ft above sea level. Significant changes in the thickness, loading, and blade-vortex interaction noise levels and radiation directions are observed across the different test sites for an AS350 helicopter flying at the same indicated airspeed and gross weight. However, the radiated noise is shown to scale with ambient pressure when the flight condition of the helicopter is defined in nondimensional terms. Although the effective tip Mach number is identified as the primary governing parameter for thickness noise, the nondimensional weight coefficient also impacts lower harmonic loading noise levels, which contribute strongly to low frequency harmonic noise radiation both in and out of the plane of the horizon. Strategies for maintaining the same nondimensional rotor operating condition under different ambient conditions are developed using an analytical model of single main rotor helicopter trim and confirmed using a CAMRAD II model of the AS350 helicopter. The ability of the Fundamental Rotorcraft Acoustics Modeling from Experiments (FRAME) technique to generalize noise measurements made under one set of ambient conditions to make accurate noise predictions under other ambient conditions is also validated.

  6. Lévy noise improves the electrical activity in a neuron under electromagnetic radiation.

    Science.gov (United States)

    Wu, Juan; Xu, Yong; Ma, Jun

    2017-01-01

    As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

  7. Lévy noise improves the electrical activity in a neuron under electromagnetic radiation.

    Directory of Open Access Journals (Sweden)

    Juan Wu

    Full Text Available As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

  8. Model scale measurements of surface ship radiated flow noise

    NARCIS (Netherlands)

    Jong, C.A.F.; Bosschers, J.; Hasenpflug, H.

    2009-01-01

    Advances in weapon and sensor capabilities are driving an increased interest in the control of underwater signatures of naval platforms. The control of machinery and propeller noise is well understood, but there is a shortfall of knowledge of the mechanisms that govern noise due to the flow around

  9. Noise Reduction on Nasal Skin Temperature Measured by Radiation Thermometer with Differential Revision Filtering

    Science.gov (United States)

    Mizuno, Tota; Nozawa, Akio; Ide, Hideto

    This paper shows noise reduction on nasal skin temperature measured by a radiation thermometer with differential revision filtering. We evaluated and examined emotion stress from the nasal skin temperature fluctuation of the space-time with the radiation thermometer. The measured data with the radiation thermometer consists of three kind of factor, because of one point [24±3φ/m] measurement system. Three kinds of factors are temperature fluctuation dependent feelings stress, noise of the radiation thermometer and the other parts which it should measure as the subject moves. We make threshold processing on a change of an area in time of a measurement signal provided in a radiation thermometer. We suggested Differential Revision Filtering (DRF) that a new method use a measurement value of change of one second and a low pass filter go through. By using this method, we got the possibility that decrease movement of a measurement and a noise of measurement device.

  10. Noise Radiation Measure-Sound Power and its Test Methods

    OpenAIRE

    Zeng Xianren; Zuo Yanyan

    2013-01-01

    This study mainly aims to study the characteristics and theory of sound radiation of steady-state vibration. Study shows that sound radiation power of steady-state vibration is constant. And taking excavator for experimental object by hemisphere surface method, the radiated sound power of the excavator is the same as testing the sound pressure on various surfaces based on relevant international standard. Finally, a test method of radiated sound power for cylindrical vibration object is proposed.

  11. Sound Radiation of Cylindrical Shells

    Directory of Open Access Journals (Sweden)

    B Alzahabi

    2016-09-01

    Full Text Available The acoustic signature of submarines is very critical in such high performance structure. Submarines are not only required to sustain very high dynamic loadings at all time, but also being able maneuver and perform their functions under sea without being detected by sonar systems. Submarines rely on low acoustic signature level to remain undetected. Reduction of sound radiation is most efficiently achieved at the design stage. Acoustic signatures may be determined by considering operational scenarios, and modal characteristics. The acoustic signature of submarines is generally of two categories; broadband which has a continuous spectrum; and a tonal noise which has discrete frequencies. The nature of sound radiation of submarine is fiction of its speed. At low speed the acoustic signature is dominated by tonal noise, while at high speed, the acoustic signature is mainly dominated by broadband noise. Submarine hulls are mainly constructed of circular cylindrical shells. Unlike that of simpler structures such as beams and plates, the modal spectrum of cylindrical shell exhibits very unique characteristics. Mode crossing, the uniqueness of modal spectrum, and the redundancy of modal constraints are just to name a few. In cylindrical shells, the lowest natural frequency is not necessarily associated with the lowest wave index. In fact, the natural frequencies do not fall in ascending order of the wave index either. Solution of the vibration problem of cylindrical shells also indicates repeated natural frequencies. These modes are referred to as double peak frequencies. Mode shapes associated with each one of the natural frequencies are usually a combination of Radial (flexural, Longitudinal (axial, and Circumferential (torsional modes. In this paper, the wave equation will be set up in terms of the pressure fluctuations, p(x, t. It will be demonstrated that the noise radiation is a fluctuating pressure wave.

  12. Research on characteristics of radiated noise of large cargo ship in shallow water

    Science.gov (United States)

    Liu, Yongdong; Zhang, Liang

    2017-01-01

    With the rapid development of the shipping industry, the number of the world's ship is gradually increasing. The characteristics of the radiated noise of the ship are also of concern. Since the noise source characteristics of multichannel interference, the surface wave and the sea temperature microstructure and other reasons, the sound signal received in the time-frequency domain has varying characteristics. The signal of the radiated noise of the large cargo ship JOCHOH from horizontal hydrophone array in some shallow water of China is processed and analyzed in the summer of 2015, and the results show that a large cargo ship JOCHOH has a number of noise sources in the direction of the ship's bow and stern lines, such as host, auxiliary and propellers. The radiating sound waves generated by these sources do not meet the spherical wave law at lower frequency in the ocean, and its radiated noise has inherent spatial distribution, the variation characteristics of the radiated noise the large cargo ship in time and frequency domain are given. The research method and results are of particular importance.

  13. Topology Model of the Flow around a Submarine Hull Form

    Science.gov (United States)

    2015-12-01

    resistance and flow noise arising from flow-structure interaction, it is necessary to test the shape of the submarine , which includes the length-to...UNCLASSIFIED Topology Model of the Flow around a Submarine Hull Form S.-K. Lee Maritime Division Defence Science and Technology Group DST-Group–TR...3177 ABSTRACT A topology model constructed from surface-streamer visualisation describes the flow around a generic conventional submarine hull form at

  14. Ship Radiated Noise Recognition Using Resonance-Based Sparse Signal Decomposition

    Directory of Open Access Journals (Sweden)

    Jiaquan Yan

    2017-01-01

    Full Text Available Under the complex oceanic environment, robust and effective feature extraction is the key issue of ship radiated noise recognition. Since traditional feature extraction methods are susceptible to the inevitable environmental noise, the type of vessels, and the speed of ships, the recognition accuracy will degrade significantly. Hence, we propose a robust time-frequency analysis method which combines resonance-based sparse signal decomposition (RSSD and Hilbert marginal spectrum (HMS analysis. First, the observed signals are decomposed into high resonance component, low resonance component, and residual component by RSSD, which is a nonlinear signal analysis method based not on frequency or scale but on resonance. High resonance component is multiple simultaneous sustained oscillations, low resonance component is nonoscillatory transients, and residual component is white Gaussian noises. According to the low-frequency periodic oscillatory characteristic of ship radiated noise, high resonance component is the purified ship radiated noise. RSSD is suited to noise suppression for low-frequency oscillation signals. Second, HMS of high resonance component is extracted by Hilbert-Huang transform (HHT as the feature vector. Finally, support vector machine (SVM is adopted as a classifier. Real audio recordings are employed in the experiments under different signal-to-noise ratios (SNRs. The experimental results indicate that the proposed method has a better recognition performance than the traditional method under different SNRs.

  15. Active control of noise radiation from vibrating structures

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    The thesis is concerned with the active control of randomly vibrating structures by means of feedback control, with particular emphasis on reducing the sound radiation from such structures. A time domain model of the structural and radiation dynamics of an actively controlled plate has been...... optimal and robust discrete-time feedback controllers for active vibration control of multimodal structures have been compared. They have been showed to yield controllers with identical frequency response characteristics, even though they employ completely different methods of numerical solutions...... developed, based on the theory of radiation filters for estimating the sound radiation from multimodal vibrations. This model has then been used in simulations of optimal feedback control, with special emphasis of the stability margins of the optimal control scheme. Two different methods of designing...

  16. Removing Noises Induced by Gamma Radiation in Cerenkov Luminescence Imaging Using a Temporal Median Filter

    Directory of Open Access Journals (Sweden)

    Xu Cao

    2016-01-01

    Full Text Available Cerenkov luminescence imaging (CLI can provide information of medical radionuclides used in nuclear imaging based on Cerenkov radiation, which makes it possible for optical means to image clinical radionuclide labeled probes. However, the exceptionally weak Cerenkov luminescence (CL from Cerenkov radiation is susceptible to lots of impulse noises introduced by high energy gamma rays generating from the decays of radionuclides. In this work, a temporal median filter is proposed to remove this kind of impulse noises. Unlike traditional CLI collecting a single CL image with long exposure time and smoothing it using median filter, the proposed method captures a temporal sequence of CL images with shorter exposure time and employs a temporal median filter to smooth a temporal sequence of pixels. Results of in vivo experiments demonstrated that the proposed temporal median method can effectively remove random pulse noises induced by gamma radiation and achieve a robust CLI image.

  17. Submarine Medicine Team

    Data.gov (United States)

    Federal Laboratory Consortium — The Submarine Medicine Team conducts basic and applied research on biomedical aspects of submarine and diving environments. It focuses on ways to optimize the health...

  18. Influence of Gear Design Parameters on Gearbox Radiated Noise

    Science.gov (United States)

    Oswald, Fred B.; Townsend, Dennis P.; Valco, Mark J.; Spencer, Robert H.; Drago, Raymond J.; Lenski, Joseph W., Jr.

    1994-01-01

    Spur and helical gears were tested in the NASA gear-noise rig to compare the noise produced by different gear designs. Sound power measurements were performed under controlled conditions for a matrix of operating conditions. Sound power was computed from near-field acoustic intensity scans taken just above the top surface of the gearbox. Test gears included four spur and five helical gear designs. The gears were designed to be as nearly identical as possible except for deliberate differences in tooth geometry and contact ratio. Test results are presented as a function of the gear design and operating conditions in the form of sound power charts and as narrow-band spectra.

  19. Improvement of road noise by reduction of acoustic radiation from body panels; Panel no hoshaon teigen ni yoru road noise no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Kamura, T.; Utsunomiya, A.; Sugihara, T.; Tobita, K. [Mazda Motor Corp., Hiroshima (Japan)

    1997-10-01

    This paper describes road noise reduction methods accomplished by reducing acoustic power radiated from body panels. Fundamental study of acoustic and dynamic characteristics with rectangular panels revealed following results: (1) The lower stiffness panel had lower radiation efficiency and made damping materials work more effective to reduce the acoustic power. (2) The acoustic power was also reduced by designing the panel so that it can generate the vibration of (2, 2) mode, which has the lowest radiation efficiency, in road noise frequency region. By applying these methods to a vehicle floor, we confirmed the improvement of road noise performance. 3 refs., 12 figs.

  20. Image noise reduction technology reduces radiation in a radial-first cardiac catheterization laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Gunja, Ateka; Pandey, Yagya [Department of Veterans Affairs, Jesse Brown VA Medical Center, Chicago, IL (United States); Division of Cardiology, Department of Medicine, University of Illinois at Chicago, Chicago, IL (United States); Xie, Hui [Division of Epidemiology and Biostatistics, University of Illinois at Chicago, Chicago, IL (United States); Faculty of Health Sciences, Simon Fraser University, Burnaby, BC (Canada); Wolska, Beata M. [Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL (United States); Shroff, Adhir R.; Ardati, Amer K. [Department of Veterans Affairs, Jesse Brown VA Medical Center, Chicago, IL (United States); Division of Cardiology, Department of Medicine, University of Illinois at Chicago, Chicago, IL (United States); Vidovich, Mladen I., E-mail: miv@uic.edu [Department of Veterans Affairs, Jesse Brown VA Medical Center, Chicago, IL (United States); Division of Cardiology, Department of Medicine, University of Illinois at Chicago, Chicago, IL (United States)

    2017-04-15

    Background: Transradial coronary angiography (TRA) has been associated with increased radiation doses. We hypothesized that contemporary image noise reduction technology would reduce radiation doses in the cardiac catheterization laboratory in a typical clinical setting. Methods and results: We performed a single-center, retrospective analysis of 400 consecutive patients who underwent diagnostic and interventional cardiac catheterizations in a predominantly TRA laboratory with traditional fluoroscopy (N = 200) and a new image noise reduction fluoroscopy system (N = 200). The primary endpoint was radiation dose (mGy cm{sup 2}). Secondary endpoints were contrast dose, fluoroscopy times, number of cineangiograms, and radiation dose by operator between the two study periods. Radiation was reduced by 44.7% between the old and new cardiac catheterization laboratory (75.8 mGy cm{sup 2} ± 74.0 vs. 41.9 mGy cm{sup 2} ± 40.7, p < 0.0001). Radiation was reduced for both diagnostic procedures (45.9%, p < 0.0001) and interventional procedures (37.7%, p < 0.0001). There was no statistically significant difference in radiation dose between individual operators (p = 0.84). In multivariate analysis, radiation dose remained significantly decreased with the use of the new system (p < 0.0001) and was associated with weight (p < 0.0001), previous coronary artery bypass grafting (p < 0.0007) and greater than 3 stents used (p < 0.0004). TRA was used in 90% of all cases in both periods. Compared with a transfemoral approach (TFA), TRA was not associated with higher radiation doses (p = 0.20). Conclusions: Image noise reduction technology significantly reduces radiation dose in a contemporary radial-first cardiac catheterization clinical practice. - Highlights: • Radial arterial access has been associated with higher doses compared to femoral access. • In a radial-first cardiac catheterization laboratory (90% radial) we examined radiation doses reduction with a contemporary image-noise

  1. Structural vibration and acoustic radiation of coupled propeller-shafting and submarine hull system due to propeller forces

    Science.gov (United States)

    Qu, Yegao; Su, Jinpeng; Hua, Hongxing; Meng, Guang

    2017-08-01

    This paper investigates the structural and acoustic responses of a coupled propeller-shafting and submarine pressure hull system under different propeller force excitations. The entire system, which consists of a rigid propeller, a main shaft, two bearings and an orthogonally stiffened pressure hull, is submerged in a heavy fluid. The shaft is elastically connected to the pressure hull by a radial bearing and a thrust bearing. The theoretical model of the structural system is formulated based on a modified variational method, in which the propeller, the main shaft and the bearings are treated as a lumped mass, an elastic beam and spatially distributed spring-damper systems, respectively. The rings and stringers in the pressure hull are modeled as discrete structural elements. The acoustic field generated by the hull is calculated using a spectral Kirchhoff-Helmholtz integral formulation. A strongly coupled structure-acoustic interaction analysis is employed to achieve reasonable solutions for the coupled system. The displacement of the pressure hull and the sound pressure of the fluid are expanded in the form of a double mixed series using Fourier series and Chebyshev orthogonal polynomials, providing a flexible way for the present method to account for the individual contributions of circumferential wave modes to the vibration and acoustic responses of the pressure hull in an analytical manner. The contributions of different circumferential wave modes of the pressure hull to the structural and acoustic responses of the coupled system under axial, transversal and vertical propeller forces are investigated. Computed results are compared with those solutions obtained from the coupled finite element/boundary element method. Effects of the ring and the bearing stiffness on the acoustic responses of the coupled system are discussed.

  2. Unsteady hydrodynamics of blade forces and acoustic responses of a model scaled submarine excited by propeller's thrust and side-forces

    Science.gov (United States)

    Wei, Yingsan; Wang, Yongsheng

    2013-04-01

    This study presents the unsteady hydrodynamics of the excitations from a 5-bladed propeller at two rotating speeds running in the wake of a small-scaled submarine and the behavior of the submarine's structure and acoustic responses under the propeller excitations. Firstly, the propeller flow and submarine flows are independently validated. The propulsion of the hull-propeller is simulated using computational fluid dynamics (CFD), so as to obtain the transient responses of the propeller excitations. Finally, the structure and acoustic responses of the submarine under propeller excitations are predicted using a finite element/boundary element model in the frequency domain. Results show that (1) the propeller excitations are tonal at the propeller harmonics, and the propeller transversal force is bigger than vertical force. (2) The structure and acoustic responses of the submarine hull is tonal mainly at the propeller harmonics and the resonant mode frequencies of the hull, and the breathing mode in axial direction as well as the bending modes in vertical and transversal directions of the hull can generate strong structure vibration and underwater noise. (3) The maximum sound pressure of the field points increases with the increasing propeller rotating speed at structure resonances and propeller harmonics, and the rudders resonant mode also contributes a lot to the sound radiation. Lastly, the critical rotating speeds of the submarine propeller are determined, which should be carefully taken into consideration when match the propeller with prime mover in the propulsion system. This work shows the importance of the propeller's tonal excitation and the breathing mode plus the bending modes in evaluating submarine's noise radiation.

  3. Noise

    Science.gov (United States)

    Noise is all around you, from televisions and radios to lawn mowers and washing machines. Normally, you ... sensitive structures of the inner ear and cause noise-induced hearing loss. More than 30 million Americans ...

  4. Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

    Science.gov (United States)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2009-01-01

    This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.

  5. Development of indirect EFBEM for radiating noise analysis including underwater problems

    Directory of Open Access Journals (Sweden)

    Hyun-Wung Kwon

    2013-09-01

    Full Text Available For the analysis of radiating noise problems in medium-to-high frequency ranges, the Energy Flow Boundary Element Method (EFBEM was developed. EFBEM is the analysis technique that applies the Boundary Element Method (BEM to Energy Flow Analysis (EFA. The fundamental solutions representing spherical wave property for radiating noise problems in open field and considering the free surface effect in underwater are developed. Also the directivity factor is developed to express wave's directivity patterns in medium-to-high frequency ranges. Indirect EFBEM by using fundamental solutions and fictitious source was applied to open field and underwater noise problems successfully. Through numerical applications, the acoustic energy density distributions due to vibration of a simple plate model and a sphere model were compared with those of commercial code, and the comparison showed good agreement in the level and pattern of the energy density distributions.

  6. Observational limitations of Bose-Einstein photon statistics and radiation noise in thermal emission

    Science.gov (United States)

    Lee, Y.-J.; Talghader, J. J.

    2018-01-01

    For many decades, theory has predicted that Bose-Einstein statistics are a fundamental feature of thermal emission into one or a few optical modes; however, the resulting Bose-Einstein-like photon noise has never been experimentally observed. There are at least two reasons for this: (1) Relationships to describe the thermal radiation noise for an arbitrary mode structure have yet to be set forth, and (2) the mode and detector constraints necessary for the detection of such light is extremely hard to fulfill. Herein, photon statistics and radiation noise relationships are developed for systems with any number of modes and couplings to an observing space. The results are shown to reproduce existing special cases of thermal emission and are then applied to resonator systems to discuss physically realizable conditions under which Bose-Einstein-like thermal statistics might be observed. Examples include a single isolated cavity and an emitter cavity coupled to a small detector space. Low-mode-number noise theory shows major deviations from solely Bose-Einstein or Poisson treatments and has particular significance because of recent advances in perfect absorption and subwavelength structures both in the long-wave infrared and terahertz regimes. These microresonator devices tend to utilize a small volume with few modes, a regime where the current theory of thermal emission fluctuations and background noise, which was developed decades ago for free-space or single-mode cavities, has no derived solutions.

  7. An Experimental Study on the Radiation Noise Characteristics of a Centrifugal Pump with Various Working Conditions

    Directory of Open Access Journals (Sweden)

    Chang Guo

    2017-12-01

    Full Text Available To investigate the radiation noise characteristics of a centrifugal pump under various working conditions, a noise measurement system is established; afterwards, the distribution of different points and intervals, as well as the overall level of noise, are studied. The total sound pressure level distribution for different points manifests the dipole and asymmetric directivity characteristics. Additionally, the acoustic energy is introduced to compare the noise of different intervals to reveal the asymmetric characteristics, and it is found that variation in working conditions has little impact on the acoustic energy distribution, and the ratio of the acoustic energy in the direction facing the tongue, as well as that in the direction against the tongue, to total acoustic energy fluctuate around 0.410 and 0.160, respectively, under various working conditions. Also, the A-weighted average sound pressure level (LpA is applied to describe the overall level of noise, and LpA increases gradually with the growth of rotational speed, but the growth slope decreases. While in the operation of throttling regulation, LpA shows the trend that first increases, then remains stable, and increases again with the growth of flow rate. This study could provide guidance for optimizing the operating conditions and noise control of centrifugal pumps.

  8. A new measurement method for separating airborne and structureborne noise radiated by aircraft type panels

    Science.gov (United States)

    Mcgary, M. C.

    1982-01-01

    The theoretical basis for and experimental validation of a measurement method for separating airborne and structure borne noise radiated by aircraft type panels are presented. An extension of the two microphone, cross spectral, acoustic intensity method combined with existing theory of sound radiation of thin shell structures of various designs, is restricted to the frequency range below the coincidence frequency of the structure. Consequently, the method lends itself to low frequency noise problems such as propeller harmonics. Both an aluminum sheet and two built up aircraft panel designs (two aluminum panels with frames and stringers) with and without added damping were measured. Results indicate that the method is quick, reliable, inexpensive, and can be applied to thin shell structures of various designs.

  9. Research on Automatic Measurement of Impulse Electromagnetic Noise (II) : Radiation from Digital IC

    OpenAIRE

    佐野, 博也; 杉之原, 広次郎; サノ, ヒロヤ; スギノハラ, コジロウ; Hiroya, SANO; Kozirou, SUGINOHARA

    1993-01-01

    Experimental investigation was made on electromagnetic noise radiated from a digital IC package on a printed circuit board with a ground plane, which simulates a multi-layer printed circuit board. We found that the principal radiation source on a printed circuit board with a ground plane is a loop composed of pins of an IC package, Vcc-pin and GND-pin, and the ground plane on the board. The loop stand out perpendicular from the board. It was also shown that the use of surface mounted devices ...

  10. Direct simulation of isolated elliptic vortices and of their radiated noise

    Energy Technology Data Exchange (ETDEWEB)

    Barre, Sebastien [Ecole Centrale de Lyon, Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, Ecully Cedex (France); Aircraft and Stores Engineering Technical Directorate, Dassault-Aviation, St Cloud Cedex (France); Bogey, Christophe; Bailly, Christophe [Ecole Centrale de Lyon, Laboratoire de Mecanique des Fluides et d' Acoustique, UMR CNRS 5509, Ecully Cedex (France)

    2008-01-15

    The aerodynamic evolution and the acoustic radiation of elliptic vortices with various aspect ratios and moderate Mach numbers are investigated by solving numerically the full compressible Navier-Stokes equations. Three behaviours are observed according to the aspect ratio {sigma}=a/b where a and b are the major and minor semi-axes of the vortices. At the small aspect ratio {sigma}=1.2, the vortex rotates at a constant angular velocity and radiates like a rotating quadrupole. At the moderate aspect ratio {sigma}=5, the vortex is initially unstable. However the growth of instability waves is inhibited by the return to axisymmetry which decreases its aspect ratio. The noise level becomes lower with time and the radiation frequency increases. For vortices with larger aspect ratios {sigma} {>=}6, the return to axisymmetry does not occur quickly enough to stop the growth of instabilities, which splits the vortices. Various mergers are then found to occur. For instance in the case {sigma}=6, several successive switches between an elliptic state and a configuration of two co-rotating vortices are observed. The present results show that the initial value of the aspect ratio yields the relative weight between the return to axisymmetry which stabilizes the vortex and the growth of instabilities which tends to split it. Moreover the noise generated by the vortices is also calculated using the analytical solution derived by Howe (J. Fluid Mech. 71:625-673, 1975) and is compared with the reference solution provided by the direct computation. This solution is found to be valid for {sigma}=1.2. An extended solution is proposed for higher aspect ratios. Finally, the pressure field appears weakly affected by the switches between the two unstable configurations in the case {sigma}=6, which underlines the difficulty to detect the split or the merger of vortices from the radiated pressure. This study also shows that elliptic vortices can be used as a basic configuration of aerodynamic

  11. Experimental investigation on noise radiation characteristics of pulse detonation engine–driven ejector

    Directory of Open Access Journals (Sweden)

    Xi-qiao Huang

    2015-06-01

    Full Text Available The noise radiation characteristics of multi-cycle pulse detonation engine with and without ejector were investigated under different operating frequencies utilizing gasoline as fuel and air as oxidizer. The straight cylindrical ejector with convergent inlet geometry was coaxially installed at different axial locations relative to the exit of the detonation tube. In all the experiments, the equivalence ratios of gasoline–air mixture and the fill fraction were 1.2 and 1.0, respectively. The experimental results implied that the addition of ejector could drastically change the far-field acoustic performance of pulse detonation engine exit and the peak sound pressure level of noise radiation was a strong function of the ejector axial position. But the peak sound pressure level was not sensitive to the operating frequencies which varied from 10 to 25 Hz. The pulse sound pressure level, however, increased with the increase in operating frequencies. The far-field jet-noise measurements of the pulse detonation engine-ejector system also showed that ejector could decrease the peak sound pressure level of pulse detonation engine. The maximum reduction was approximately 8.5 dB. For the current pulse detonation engine test conditions, an optimum ejector position was found to be a downstream axial placement of x/DPDE  = 0.5.

  12. Low cost submarine robot

    OpenAIRE

    Ponlachart Chotikarn; Werapong Koedsin; Boonlua Phongdara; Pattara Aiyarak

    2010-01-01

    A submarine robot is a semi-autonomous submarine robot used mainly for marine environmental research. We aim todevelop a low cost, semi-autonomous submarine robot which is able to travel underwater. The robot’s structure was designedand patented using a novel idea of the diving system employing a volume adjustment mechanism to vary the robot’s density.A light weight, flexibility and small structure provided by PVC can be used to construct the torpedo-liked shape robot.Hydraulic seal and O-rin...

  13. Low cost submarine robot

    Directory of Open Access Journals (Sweden)

    Ponlachart Chotikarn

    2010-10-01

    Full Text Available A submarine robot is a semi-autonomous submarine robot used mainly for marine environmental research. We aim todevelop a low cost, semi-autonomous submarine robot which is able to travel underwater. The robot’s structure was designedand patented using a novel idea of the diving system employing a volume adjustment mechanism to vary the robot’s density.A light weight, flexibility and small structure provided by PVC can be used to construct the torpedo-liked shape robot.Hydraulic seal and O-ring rubbers are used to prevent water leaking. This robot is controlled by a wired communicationsystem.

  14. [Effects of submarine engine room steady noise on the compound action potential tuning curves and its relation to cochlear pathology in guinea pigs].

    Science.gov (United States)

    Pei, H

    1990-06-01

    Compound Action Potential Tuning Curves (CAP-TC) for tone pip of 2k, 4 kHz were examined in 8 guinea pigs before and after exposure to noise with main energy centered in the range of 0.25-4.0 kHz. CAP-TC was measured with the pure tone simultaneous masking profiles. AP was evoked by tone pip with an intensity of 10 dB above threshold. Masker level producing 40% reduction in AP amplitude was used. Relations between changes in CAP-TC and AP threshold shifts and the pathology of the stereocilia of hair cells were evaluated by surface preparation and SEM observation in 13 ears. After noise exposure, animals with damaged stereocilia showed AP threshold shift of 20-50 dB, deteriorations of CAP-TC, decrease of Q10 dB value, threshold shift of characteristic frequencies (CF) and displacement of CF towards higher frequencies. It showed that stereocilia damage may affect the susceptibility and frequency selectivity of the cochlea. We consider the CAP-TC may be an useful and sensitive index for detecting physiological and pathological conditions of the cochlea.

  15. Viscoelastic property tuning for reducing noise radiated by switched-reluctance machines

    Science.gov (United States)

    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.

  16. Response of Electrical Activity in an Improved Neuron Model under Electromagnetic Radiation and Noise.

    Science.gov (United States)

    Zhan, Feibiao; Liu, Shenquan

    2017-01-01

    Electrical activities are ubiquitous neuronal bioelectric phenomena, which have many different modes to encode the expression of biological information, and constitute the whole process of signal propagation between neurons. Therefore, we focus on the electrical activities of neurons, which is also causing widespread concern among neuroscientists. In this paper, we mainly investigate the electrical activities of the Morris-Lecar (M-L) model with electromagnetic radiation or Gaussian white noise, which can restore the authenticity of neurons in realistic neural network. First, we explore dynamical response of the whole system with electromagnetic induction (EMI) and Gaussian white noise. We find that there are slight differences in the discharge behaviors via comparing the response of original system with that of improved system, and electromagnetic induction can transform bursting or spiking state to quiescent state and vice versa. Furthermore, we research bursting transition mode and the corresponding periodic solution mechanism for the isolated neuron model with electromagnetic induction by using one-parameter and bi-parameters bifurcation analysis. Finally, we analyze the effects of Gaussian white noise on the original system and coupled system, which is conducive to understand the actual discharge properties of realistic neurons.

  17. Response of Electrical Activity in an Improved Neuron Model under Electromagnetic Radiation and Noise

    Science.gov (United States)

    Zhan, Feibiao; Liu, Shenquan

    2017-01-01

    Electrical activities are ubiquitous neuronal bioelectric phenomena, which have many different modes to encode the expression of biological information, and constitute the whole process of signal propagation between neurons. Therefore, we focus on the electrical activities of neurons, which is also causing widespread concern among neuroscientists. In this paper, we mainly investigate the electrical activities of the Morris-Lecar (M-L) model with electromagnetic radiation or Gaussian white noise, which can restore the authenticity of neurons in realistic neural network. First, we explore dynamical response of the whole system with electromagnetic induction (EMI) and Gaussian white noise. We find that there are slight differences in the discharge behaviors via comparing the response of original system with that of improved system, and electromagnetic induction can transform bursting or spiking state to quiescent state and vice versa. Furthermore, we research bursting transition mode and the corresponding periodic solution mechanism for the isolated neuron model with electromagnetic induction by using one-parameter and bi-parameters bifurcation analysis. Finally, we analyze the effects of Gaussian white noise on the original system and coupled system, which is conducive to understand the actual discharge properties of realistic neurons. PMID:29209192

  18. Response of Electrical Activity in an Improved Neuron Model under Electromagnetic Radiation and Noise

    Directory of Open Access Journals (Sweden)

    Feibiao Zhan

    2017-11-01

    Full Text Available Electrical activities are ubiquitous neuronal bioelectric phenomena, which have many different modes to encode the expression of biological information, and constitute the whole process of signal propagation between neurons. Therefore, we focus on the electrical activities of neurons, which is also causing widespread concern among neuroscientists. In this paper, we mainly investigate the electrical activities of the Morris-Lecar (M-L model with electromagnetic radiation or Gaussian white noise, which can restore the authenticity of neurons in realistic neural network. First, we explore dynamical response of the whole system with electromagnetic induction (EMI and Gaussian white noise. We find that there are slight differences in the discharge behaviors via comparing the response of original system with that of improved system, and electromagnetic induction can transform bursting or spiking state to quiescent state and vice versa. Furthermore, we research bursting transition mode and the corresponding periodic solution mechanism for the isolated neuron model with electromagnetic induction by using one-parameter and bi-parameters bifurcation analysis. Finally, we analyze the effects of Gaussian white noise on the original system and coupled system, which is conducive to understand the actual discharge properties of realistic neurons.

  19. New image-processing and noise-reduction software reduces radiation dose during complex endovascular procedures.

    Science.gov (United States)

    Kirkwood, Melissa L; Guild, Jeffrey B; Arbique, Gary M; Tsai, Shirling; Modrall, J Gregory; Anderson, Jon A; Rectenwald, John; Timaran, Carlos

    2016-11-01

    A new proprietary image-processing system known as AlluraClarity, developed by Philips Healthcare (Best, The Netherlands) for radiation-based interventional procedures, claims to lower radiation dose while preserving image quality using noise-reduction algorithms. This study determined whether the surgeon and patient radiation dose during complex endovascular procedures (CEPs) is decreased after the implementation of this new operating system. Radiation dose to operators, procedure type, reference air kerma, kerma area product, and patient body mass index were recorded during CEPs on two Philips Allura FD 20 fluoroscopy systems with and without Clarity. Operator dose during CEPs was measured using optically stimulable, luminescent nanoDot (Landauer Inc, Glenwood, Ill) detectors placed outside the lead apron at the left upper chest position. nanoDots were read using a microStar ii (Landauer Inc) medical dosimetry system. For the CEPs in the Clarity group, the radiation dose to surgeons was also measured by the DoseAware (Philips Healthcare) personal dosimetry system. Side-by-side measurements of DoseAware and nanoDots allowed for cross-calibration between systems. Operator effective dose was determined using a modified Niklason algorithm. To control for patient size and case complexity, the average fluoroscopy dose rate and the dose per radiographic frame were adjusted for body mass index differences and then compared between the groups with and without Clarity by procedure. Additional factors, for example, physician practice patterns, that may have affected operator dose were inferred by comparing the ratio of the operator dose to procedural kerma area product with and without Clarity. A one-sided Wilcoxon rank sum test was used to compare groups for radiation doses, reference air kermas, and operating practices for each procedure type. The analysis included 234 CEPs; 95 performed without Clarity and 139 with Clarity. Practice patterns of operators during

  20. Discrete-frequency and broadband noise radiation from diesel engine cooling fans

    Science.gov (United States)

    Kim, Geon-Seok

    This effort focuses on measuring and predicting the discrete-frequency and broadband noise radiated by diesel engine cooling fans. Unsteady forces developed by the interaction of the fan blade with inlet flow are the dominant source for both discrete-frequency and broadband noise of the subject propeller fan. In many cases, a primary source of discrepancy between fan noise prediction and measurement is due to incomplete description of the fan inflow. Particularly, in such engine cooling systems where space is very limited, it would be very difficult, if not, impossible to measure the fan inflow velocity field using the conventional, stationary hot-wire method. Instead, the fan inflow was measured with two-component x-type hot-film probes attached very close to the leading edge of a rotating blade. One of the advantages of the blade-mounted-probe measurement technique is that it measures velocities relative to the rotating probe, which enables the acquired data to be applied directly in many aerodynamic theories that have been developed for the airfoil fixed-coordinate system. However, the velocity time data measured by this technique contains the spatially non-uniform mean velocity field along with the temporal fluctuations. A phase-locked averaging technique was successfully employed to decompose the velocity data into time-invariant flow distortions and fluctuations due to turbulence. The angles of attack of the fan blades, obtained from inlet flow measurements, indicate that the blades are stalled. The fan's radiated noise was measured without contamination from the engine noise by driving the fan with an electric motor. The motor operated at a constant speed while a pair of speed controllable pulleys controlled the fan speed. Narrowband and 1/3-octave band sound power of the cooling fan was measured by using the comparison method with a reference sound source in a reverberant room. The spatially non-uniform mean velocity field was used in axial-flow fan noise

  1. Optimizing CT technique to reduce radiation dose: effect of changes in kVp, iterative reconstruction, and noise index on dose and noise in a human cadaver.

    Science.gov (United States)

    Chang, Kevin J; Collins, Scott; Li, Baojun; Mayo-Smith, William W

    2017-06-01

    For assessment of the effect of varying the peak kilovoltage (kVp), the adaptive statistical iterative reconstruction technique (ASiR), and automatic dose modulation on radiation dose and image noise in a human cadaver, a cadaver torso underwent CT scanning at 80, 100, 120 and 140 kVp, each at ASiR settings of 0, 30 and 50 %, and noise indices (NIs) of 5.5, 11 and 22. The volume CT dose index (CTDIvol), image noise, and attenuation values of liver and fat were analyzed for 20 data sets. Size-specific dose estimates (SSDEs) and liver-to-fat contrast-to-noise ratios (CNRs) were calculated. Values for different combinations of kVp, ASiR, and NI were compared. The CTDIvol varied by a power of 2 with kVp values between 80 and 140 without ASiR. Increasing ASiR levels allowed a larger decrease in CTDIvol and SSDE at higher kVp than at lower kVp while image noise was held constant. In addition, CTDIvol and SSDE decreased with increasing NI at each kVp, but the decrease was greater at higher kVp than at lower kVp. Image noise increased with decreasing kVp despite a fixed NI; however, this noise could be offset with the use of ASiR. The CT number of the liver remained unchanged whereas that of fat decreased as the kVp decreased. Image noise and dose vary in a complicated manner when the kVp, ASiR, and NI are varied in a human cadaver. Optimization of CT protocols will require balancing of the effects of each of these parameters to maximize image quality while minimizing dose.

  2. A study on the radiation damage and recovery of neutron irradiated vessel steel using magnetic Barkhausen noise

    Science.gov (United States)

    Park, Duck-Gun; Jeong, Hee-Tae; Hong, Jun-Hwa

    1999-04-01

    The radiation damage and thermal recovery characteristic of neutron irradiated SA508-3 reactor pressure vessel steel specimens have been investigated. Two recovery stages were identified from the results of hardness measurements during isochronal annealing and the mechanism responsible for the two stages was explained by using the results of Barkhausen noise measurement on the basis of the interaction between radiation induced defects and the magnetic domain wall. The coercivity was not changed by neutron irradiation, whereas the maximum magnetic induction increased. Barkhausen noise parameters associated with the domain wall motion were decreased by neutron irradiation and recovered with subsequent heat treatments.

  3. Submarine Salt Karst Terrains

    Directory of Open Access Journals (Sweden)

    Nico Augustin

    2016-06-01

    Full Text Available Karst terrains that develop in bodies of rock salt (taken as mainly of halite, NaCl are special not only for developing in one of the most soluble of all rocks, but also for developing in one of the weakest rocks. Salt is so weak that many surface-piercing salt diapirs extrude slow fountains of salt that that gravity spread downslope over deserts on land and over sea floors. Salt fountains in the deserts of Iran are usually so dry that they flow at only a few cm/yr but the few rain storms a decade so soak and weaken them that they surge at dm/day for a few days. We illustrate the only case where the rates at which different parts of one of the many tens of subaerial salt karst terrains in Iran flows downslope constrains the rates at which its subaerial salt karst terrains form. Normal seawater is only 10% saturated in NaCl. It should therefore be sufficiently aggressive to erode karst terrains into exposures of salt on the thousands of known submarine salt extrusions that have flowed or are still flowing over the floors of hundreds of submarine basins worldwide. However, we know of no attempt to constrain the processes that form submarine salt karst terrains on any of these of submarine salt extrusions. As on land, many potential submarine karst terrains are cloaked by clastic and pelagic sediments that are often hundreds of m thick. Nevertheless, detailed geophysical and bathymetric surveys have already mapped likely submarine salt karst terrains in at least the Gulf of Mexico, and the Red Sea. New images of these two areas are offered as clear evidence of submarine salt dissolution due to sinking or rising aggressive fluids. We suggest that repeated 3D surveys of distinctive features (± fixed seismic reflectors of such terrains could measure any downslope salt flow and thus offer an exceptional opportunity to constrain the rates at which submarine salt karst terrains develop. Such rates are of interest to all salt tectonicians and the many

  4. Submarine Warfare in the 20th & 21st Centuries: A Bibliography

    National Research Council Canada - National Science Library

    Huygen, Michaele

    2003-01-01

    There are constant motions in the sea caused by atmospheric and seabed activities volcanic disruptions marine animals ships and submarines -- all of which create what is called the ambient noise level of the oceans...

  5. Research on Ship-Radiated Noise Denoising Using Secondary Variational Mode Decomposition and Correlation Coefficient.

    Science.gov (United States)

    Li, Yuxing; Li, Yaan; Chen, Xiao; Yu, Jing

    2017-12-26

    As the sound signal of ships obtained by sensors contains other many significant characteristics of ships and called ship-radiated noise (SN), research into a denoising algorithm and its application has obtained great significance. Using the advantage of variational mode decomposition (VMD) combined with the correlation coefficient for denoising, a hybrid secondary denoising algorithm is proposed using secondary VMD combined with a correlation coefficient (CC). First, different kinds of simulation signals are decomposed into several bandwidth-limited intrinsic mode functions (IMFs) using VMD, where the decomposition number by VMD is equal to the number by empirical mode decomposition (EMD); then, the CCs between the IMFs and the simulation signal are calculated respectively. The noise IMFs are identified by the CC threshold and the rest of the IMFs are reconstructed in order to realize the first denoising process. Finally, secondary denoising of the simulation signal can be accomplished by repeating the above steps of decomposition, screening and reconstruction. The final denoising result is determined according to the CC threshold. The denoising effect is compared under the different signal-to-noise ratio and the time of decomposition by VMD. Experimental results show the validity of the proposed denoising algorithm using secondary VMD (2VMD) combined with CC compared to EMD denoising, ensemble EMD (EEMD) denoising, VMD denoising and cubic VMD (3VMD) denoising, as well as two denoising algorithms presented recently. The proposed denoising algorithm is applied to feature extraction and classification for SN signals, which can effectively improve the recognition rate of different kinds of ships.

  6. Research on Ship-Radiated Noise Denoising Using Secondary Variational Mode Decomposition and Correlation Coefficient

    Directory of Open Access Journals (Sweden)

    Yuxing Li

    2017-12-01

    Full Text Available As the sound signal of ships obtained by sensors contains other many significant characteristics of ships and called ship-radiated noise (SN, research into a denoising algorithm and its application has obtained great significance. Using the advantage of variational mode decomposition (VMD combined with the correlation coefficient for denoising, a hybrid secondary denoising algorithm is proposed using secondary VMD combined with a correlation coefficient (CC. First, different kinds of simulation signals are decomposed into several bandwidth-limited intrinsic mode functions (IMFs using VMD, where the decomposition number by VMD is equal to the number by empirical mode decomposition (EMD; then, the CCs between the IMFs and the simulation signal are calculated respectively. The noise IMFs are identified by the CC threshold and the rest of the IMFs are reconstructed in order to realize the first denoising process. Finally, secondary denoising of the simulation signal can be accomplished by repeating the above steps of decomposition, screening and reconstruction. The final denoising result is determined according to the CC threshold. The denoising effect is compared under the different signal-to-noise ratio and the time of decomposition by VMD. Experimental results show the validity of the proposed denoising algorithm using secondary VMD (2VMD combined with CC compared to EMD denoising, ensemble EMD (EEMD denoising, VMD denoising and cubic VMD (3VMD denoising, as well as two denoising algorithms presented recently. The proposed denoising algorithm is applied to feature extraction and classification for SN signals, which can effectively improve the recognition rate of different kinds of ships.

  7. Computation of Aerodynamic Noise Radiated from Ducted Tail Rotor Using Boundary Element Method

    Directory of Open Access Journals (Sweden)

    Yunpeng Ma

    2017-01-01

    Full Text Available A detailed aerodynamic performance of a ducted tail rotor in hover has been numerically studied using CFD technique. The general governing equations of turbulent flow around ducted tail rotor are given and directly solved by using finite volume discretization and Runge-Kutta time integration. The calculations of the lift characteristics of the ducted tail rotor can be obtained. In order to predict the aerodynamic noise, a hybrid method combining computational aeroacoustic with boundary element method (BEM has been proposed. The computational steps include the following: firstly, the unsteady flow around rotor is calculated using the CFD method to get the noise source information; secondly, the radiate sound pressure is calculated using the acoustic analogy Curle equation in the frequency domain; lastly, the scattering effect of the duct wall on the propagation of the sound wave is presented using an acoustic thin-body BEM. The aerodynamic results and the calculated sound pressure levels are compared with the known technique for validation. The sound pressure directivity and scattering effect are shown to demonstrate the validity and applicability of the method.

  8. Submarine permafrost depth from ambient seismic noise

    OpenAIRE

    Overduin, P. Paul; Haberland, Christian; Ryberg, Trond; Kneier, Fabian; Jacobi, Tim; Grigoriev, M. N.; Ohrnberger, Matthias

    2015-01-01

    Permafrost inundated since the last glacial maximum is degrading, potentially releasing trapped or stabilized greenhouse gases, but few observations of the depth of ice-bonded permafrost (IBP) below the seafloor exist for most of the arctic continental shelf. We use spectral ratios of the ambient vibration seismic wavefield, together with estimated shear wave velocity from the dispersion curves of surface waves, for estimating the thickness of the sediment overlying the IBP. Peaks in spectral...

  9. Submarine permafrost depth from ambient seismic noise

    Science.gov (United States)

    Overduin, Pier P.; Haberland, Christian; Ryberg, Trond; Kneier, Fabian; Jacobi, Tim; Grigoriev, Mikhail. N.; Ohrnberger, Matthias

    2015-09-01

    Permafrost inundated since the last glacial maximum is degrading, potentially releasing trapped or stabilized greenhouse gases, but few observations of the depth of ice-bonded permafrost (IBP) below the seafloor exist for most of the arctic continental shelf. We use spectral ratios of the ambient vibration seismic wavefield, together with estimated shear wave velocity from the dispersion curves of surface waves, for estimating the thickness of the sediment overlying the IBP. Peaks in spectral ratios modeled for three-layered 1-D systems correspond with varying thickness of the unfrozen sediment. Seismic receivers were deployed on the seabed around Muostakh Island in the central Laptev Sea, Siberia. We derive depths of the IBP between 3.7 and 20.7 m ± 15%, increasing with distance from the shoreline. Correspondence between expected permafrost distribution, modeled response, and observational data suggests that the method is promising for the determination of the thickness of unfrozen sediment.

  10. Accuracy verification and analysis of SEA method for calculating radiation noise pressure of submerged cylindrical shell

    Directory of Open Access Journals (Sweden)

    ZHANG Kai

    2017-08-01

    Full Text Available Statistical Energy Analysis(SEAis an effective method for solving high frequency structural vibration and acoustic radiation problems. When we use it to analyze submerged structures, it is necessary to consider the actions of fluid as'heavy fluid' relative to structures, which differs from when it is used in the air. The simple model of a submerged cylindrical shell is used to calculate at a higher frequency using FEM/BEM. The SEA and FEM method are then used to calculate the radiation sound pressure level, verifying the accuracy of the SEA prediction for submerged structures. The classified method of subsystems and the effect of the error of the internal loss factor on the accuracy of the results are explored. The calculated results of SEA and FEM/BEM are very different below 400 Hz, and basically the same above 400 Hz. The error caused by the division of different subsystems is about 5 dB. The error in the calculation results caused by the error of the internal loss factor is 2-3 dB. It is possible to use SEA to calculate the radiated noise of an underwater cylindrical shell when the modal density is high enough.For the cylindrical shell, dividing the subsystems along the circumference is not reliable at a low frequency, as it may lead to inaccurate calculation results. At a high frequency, it is more accurate to divide the subsystems along the circumference than the axle. For subsystems with high energy, the internal loss factor has a greater effect on the simulation results, so a more accurate way should be taken to determine the internal loss factor of subsystems with high energy.

  11. Deep-water measurements of container ship radiated noise signatures and directionality.

    Science.gov (United States)

    Gassmann, Martin; Wiggins, Sean M; Hildebrand, John A

    2017-09-01

    Underwater radiated noise from merchant ships was measured opportunistically from multiple spatial aspects to estimate signature source levels and directionality. Transiting ships were tracked via the Automatic Identification System in a shipping lane while acoustic pressure was measured at the ships' keel and beam aspects. Port and starboard beam aspects were 15°, 30°, and 45° in compliance with ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Additional recordings were made at a 10° starboard aspect. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd's mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. Results were exemplified with a 4870 and a 10 036 twenty-foot equivalent unit container ship at 40%-56% and 87% of service speeds, respectively. For the larger ship, opportunistic ANSI/ISO broadband levels were 195 (surface-affected) and 209 (surface-corrected) dB re 1 μPa 2 1 m. Directionality at a propeller blade rate of 8 Hz exhibited asymmetries in stern-bow (<6 dB) and port-starboard (<9 dB) direction. Previously reported broadband levels at 10° aspect from McKenna, Ross, Wiggins, and Hildebrand [(2012b). J. Acoust. Soc. Am. 131, 92-103] may be ∼12 dB lower than respective surface-affected ANSI/ISO standard derived levels.

  12. A method to obtain the same levels of CT image noise for patients of various sizes, to minimize radiation dose.

    Science.gov (United States)

    Starck, G; Lönn, L; Cederblad, A; Forssell-Aronsson, E; Sjöström, L; Alpsten, M

    2002-02-01

    The aim of this study was to develop a method of obtaining the same levels of CT image noise for patients of various sizes to minimize radiation dose. Two CT systems were evaluated regarding noise characteristics using phantoms and dosimetric measurements. Both CT systems performed well at dose levels used in normal clinical imaging, but only one was found to be suitable for low radiation dose applications. The CT system with the lowest noise level was used for further detailed studies. A simple strategy for manual selection of patient-specific scan parameters, considering patient size and required image quality, was implemented and verified on 11 volunteers. Images were obtained with at least the prescribed image quality at significantly reduced radiation dose levels compared with standard scan parameters. Depending on the diameter of the tomographic section, i.e. size of the subject, the dose levels could be reduced to 1-45% of the radiation dose with standard scan parameters (120 kV, 250 mAs, 10 mm). The results indicate a general potential for dose reduction in CT for slim patients. For tissue volume determination, large dose reductions can be achieved by adjusting the scan parameters for each individual. The concept of patient-specific scan parameters could be fully automated in the CT system design, but would require the scan to be specified in terms of image quality rather than X-ray tube load.

  13. Maximum entropy inference of seabed attenuation parameters using ship radiated broadband noise.

    Science.gov (United States)

    Knobles, D P

    2015-12-01

    The received acoustic field generated by a single passage of a research vessel on the New Jersey continental shelf is employed to infer probability distributions for the parameter values representing the frequency dependence of the seabed attenuation and the source levels of the ship. The statistical inference approach employed in the analysis is a maximum entropy methodology. The average value of the error function, needed to uniquely specify a conditional posterior probability distribution, is estimated with data samples from time periods in which the ship-receiver geometry is dominated by either the stern or bow aspect. The existence of ambiguities between the source levels and the environmental parameter values motivates an attempt to partially decouple these parameter values. The main result is the demonstration that parameter values for the attenuation (α and the frequency exponent), the sediment sound speed, and the source levels can be resolved through a model space reduction technique. The results of this multi-step statistical inference developed for ship radiated noise is then tested by processing towed source data over the same bandwidth and source track to estimate continuous wave source levels that were measured independently with a reference hydrophone on the tow body.

  14. Observation of Synchrotron Radiation Using Low Noise Block (LNB) at ANKA

    CERN Document Server

    Judin, V; Hofmann, A; Huttel, E; Kehrer, B; Klein, M; Marsching, S; Muller, A-S; Smale, N; Caspers, F

    2011-01-01

    Generally Coherent Synchrotron Radiation (CSR) is emitted for wavelengths longer than or equal the bunch length, so for CSR in the THz-range short bunches are required. There are two types of detectors in this range of the spectrum: slow detectors like a golay cell or pyrometric detectors (used for e.g. imaging, spectroscopy) and fast detectors like superconducting bolometer detector systems and Schottky Barrier diodes (used for e.g. the investigation of dynamic processes in accelerator physics). The hot electron bolometer (HEB) detector system is a member of second group. It is very fast and has broad spectral characteristics, but unfortunately very expensive and have to be cooled using liquid helium. If the broad spectral response is not important, it will be suitably to use a Schottky Barrier diode instead. These detectors are massively cheaper but also slower. As an alternative to a Schottky diode a LNB (Low Noise Block) can be also used. It is usually used in standard TV-SAT-receivers. Due to mass produc...

  15. [Blocking 1800 MHz mobile phone radiation-induced reactive oxygen species production and DNA damage in lens epithelial cells by noise magnetic fields].

    Science.gov (United States)

    Wu, Wei; Yao, Ke; Wang, Kai-jun; Lu, De-qiang; He, Ji-liang; Xu, Li-hong; Sun, Wen-jun

    2008-01-01

    To investigate whether the exposure to the electromagnetic noise can block reactive oxygen species (ROS) production and DNA damage of lens epithelial cells induced by 1800 MHz mobile phone radiation. The DCFH-DA method and comet assay were used respectively to detect the intracellular ROS and DNA damage of cultured human lens epithelial cells induced by 4 W/kg 1800 MHz mobile phone radiation or/and 2 muT electromagnetic noise for 24 h intermittently. 1800 MHz mobile phone radiation at 4 W/kg for 24 h increased intracellular ROS and DNA damage significantly (PDNA damage of mobile phone radiation plus noise group were not significant enhanced (P>0.05) as compared to sham exposure group. Electromagnetic noise can block intracellular ROS production and DNA damage of human lens epithelial cells induced by 1800 MHz mobile phone radiation.

  16. Relationship between work stress and health in submariners

    Directory of Open Access Journals (Sweden)

    Nan-nan JIANG

    2013-09-01

    Full Text Available Objective To explore the relationship between work stress and health in submariners. Methods In April 2008, 272 submariners trained in a navy base were selected as study subjects by random group sampling method, and tested by primary personal information questionnaire, self-rated health measurement scale (SRHMS, self-developed submariners' work stressors questionnaire, and work stress self-rated scale. Physical health, mental health and social health of submariners were analyzed, and scores were compared with the norm of reference scores. Correlations were analyzed respectively between 10 items of submariners' general information (including age, length of military service, education degree, years at the present post, times of receiving awards, on-duty hours, off-duty hours, hours of sleep, lost days of leave, positive attitude to work and their physical health score, mental health score, social health score, total health score, as well as between 15 submariners' work stressors (including workrelated risks, diet problems, high temperature, humidity and noise in workplace, shortage of clean clothes, illness, losing contact with outside, lack of information about the task, lacking supports from family members, relationship problems, lack of involvement in task decisions, boring and dull work, on duty, heavy work, high quality of work, coping with unexpected threat and their physical health score, mental health score, social health score and total health score. Results No significant difference was found between submariners' SRHMS total score and the normal referenced score (t=0.56, P>0.05, but the physical health score and mental health score were significantly lower than normal referenced scores respectively (t=–2.172, P<0.05; t=–3.299, P<0.01, and the social health score was significantly higher than normal referenced score (t=9.331, P<0.001. The age, length of military service, years at present post of submariners were related

  17. Patient radiation dose reduction using an X-ray imaging noise reduction technology for cardiac angiography and intervention.

    Science.gov (United States)

    Nakamura, Shigeru; Kobayashi, Tomoko; Funatsu, Atsushi; Okada, Tadahisa; Mauti, Maria; Waizumi, Yuki; Yamada, Shinichi

    2016-05-01

    Coronary angiography and intervention can expose patients to high radiation dose. This retrospective study quantifies the patient dose reduction due to the introduction of a novel X-ray imaging noise reduction technology using advanced real-time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure in interventional cardiology. Patient, procedure and radiation dose data were retrospectively collected in the period August 2012-August 2013 for 883 patients treated with the image noise reduction technology (referred as "new system"). The same data were collected for 1083 patients in the period April 2011-July 2012 with a system using state-of-the-art image processing and reference acquisition chain (referred as "reference system"). Procedures were divided into diagnostic (CAG) and intervention (PCI). Acquisition parameters such as fluoroscopy time, volume of contrast medium, number of exposure images and number of stored fluoroscopy images were collected to classify procedure complexity. The procedural dose reduction was investigated separately for three main cardiologists. The new system provides significant dose reduction compared to the reference system. Median DAP values decreased for all procedures (p X-ray imaging technology combining advanced real-time image noise reduction algorithms and anatomy-specific optimized fluoroscopy and cine acquisition chain provides 66 % patient dose reduction in interventional cardiology.

  18. Pediatric cT: Implementation of ASIR for Substantial Radiation Dose Reduction While Maintaining Pre-ASIR Image Noise1

    Science.gov (United States)

    Brady, Samuel L.; Moore, Bria M.; Yee, Brian S.; Kaufman, Robert A.

    2015-01-01

    Purpose To determine a comprehensive method for the implementation of adaptive statistical iterative reconstruction (ASIR) for maximal radiation dose reduction in pediatric computed tomography (CT) without changing the magnitude of noise in the reconstructed image or the contrast-to-noise ratio (CNR) in the patient. Materials and Methods The institutional review board waived the need to obtain informed consent for this HIPAA-compliant quality analysis. Chest and abdominopelvic CT images obtained before ASIR implementation (183 patient examinations; mean patient age, 8.8 years ± 6.2 [standard deviation]; range, 1 month to 27 years) were analyzed for image noise and CNR. These measurements were used in conjunction with noise models derived from anthropomorphic phantoms to establish new beam current–modulated CT parameters to implement 40% ASIR at 120 and 100 kVp without changing noise texture or magnitude. Image noise was assessed in images obtained after ASIR implementation (492 patient examinations; mean patient age, 7.6 years ± 5.4; range, 2 months to 28 years) the same way it was assessed in the pre-ASIR analysis. Dose reduction was determined by comparing size-specific dose estimates in the pre- and post-ASIR patient cohorts. Data were analyzed with paired t tests. Results With 40% ASIR implementation, the average relative dose reduction for chest CT was 39% (2.7/4.4 mGy), with a maximum reduction of 72% (5.3/18.8 mGy). The average relative dose reduction for abdominopelvic CT was 29% (4.8/6.8 mGy), with a maximum reduction of 64% (7.6/20.9 mGy). Beam current modulation was unnecessary for patients weighing 40 kg or less. The difference between 0% and 40% ASIR noise magnitude was less than 1 HU, with statistically nonsignificant increases in patient CNR at 100 kVp of 8% (15.3/14.2; P = .41) for chest CT and 13% (7.8/6.8; P = .40) for abdominopelvic CT. Conclusion Radiation dose reduction at pediatric CT was achieved when 40% ASIR was implemented as a dose

  19. SCICEX: Submarine Arctic Science Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration among the operational Navy, research agencies, and the marine research community...

  20. The Submarine, 1776-1918

    National Research Council Canada - National Science Library

    Uhlig, Frank

    2004-01-01

    When, on 11 April 1900, the U.S. Navy thought the Holland, named for its designer, that little submarine joined a fleet consisting of two armored cruisers, six monitors, seven first and second-class battleships, and seventeen each...

  1. The Evaluation of Sanitary-Epidemiological Service Conditions On a Submarine

    Directory of Open Access Journals (Sweden)

    Żychliński Michał

    2017-03-01

    Full Text Available Service on a submarine is the most stressful and psychologically challenging form of military service. It is characterised by specific living and sanitaryepidemiological conditions which are far from typical. This work is based on the analyses of reports formulated from research conducted by a working environment laboratory, and on the control protocols of the sanitary supervision and control team (WOMP Gdynia, from the Kobben submersible vessels in the years 2014 and 2015. Military Centres of Preventive Medicine hold supervision over Military Units pursuant to generally applicable regulations in the civil environment and standardised NATO norms. Measurements concern the level of noise, mechanical vibrations, chemical agents, electromagnetic radiation, physiochemical and biological water and kitchenware tests. The objective of the research is to evaluate the service conditions on a submersible vessel with regard to sanitary-epidemiological aspects such as exposure to infectious and occupational diseases. In selected stations, the conducted measurements indicate an increased level of noise, electromagnetic radiation and excess quantities of bacteria colonies on kitchenware.

  2. Radiation of Air-Borne Noise in Non-Homogeneous Wind and Temperature Fields using FEM Analysis

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Nielsen, Søren R. K.; Krenk, S.

    1999-01-01

    The paper describes analysis in the time domain of noise propagating in non-homogeneous mean wind or temperature fields. The analysis is based on a field equation for the velocity potential, which contains strong convection terms. In order to circumvent the problem of numerical instability and loss...... by a conventional Galerkin approach. The radiation condition is an impedance condition for wave propagation towards the artificial boundary at an oblique angle. The propagation angle is estimated geometrically with due consideration of the mean wind velocity. The method has been applied to a 2-dimensional point...

  3. Photon noise limited radiation detection with lens-antenna coupled microwave kinetic inductance detectors

    NARCIS (Netherlands)

    Yates, S. J. C.; Baselmans, J. J. A.; Endo, A.; Janssen, R. M. J.; Ferrari, L.; Diener, P.; Barychev, Andrei

    2011-01-01

    Microwave kinetic inductance detectors (MKIDs) have shown great potential for sub-mm instrumentation because of the high scalability of the technology. Here, we demonstrate for the first time in the sub-mm band (0.1-2 mm) a photon noise limited performance of a small antenna coupled MKID detector

  4. Photon noise limited radiation detection with lens-antenna coupled microwave kinetic inductance detectors

    NARCIS (Netherlands)

    Yates, S.J.C.; Baselmans, J.J.A.; Endo, A.; Janssen, R.M.J.; Ferrari, L.; Diener, P.; Baryshev, A.M.

    2011-01-01

    Microwave kinetic inductance detectors (MKIDs) have shown great potential for sub-mm instrumentation because of the high scalability of the technology. Here, we demonstrate for the first time in the sub-mm band (0.1–2 mm) a photon noise limited performance of a small antenna coupled MKID detector

  5. Denoising and Feature Extraction Algorithms Using NPE Combined with VMD and Their Applications in Ship-Radiated Noise

    Directory of Open Access Journals (Sweden)

    Yuxing Li

    2017-11-01

    Full Text Available A new denoising algorithm and feature extraction algorithm that combine a new kind of permutation entropy (NPE and variational mode decomposition (VMD are put forward in this paper. VMD is a new self-adaptive signal processing algorithm, which is more robust to sampling and noise, and also can overcome the problem of mode mixing in empirical mode decomposition (EMD and ensemble EMD (EEMD. Permutation entropy (PE, as a nonlinear dynamics parameter, is a powerful tool that can describe the complexity of a time series. NPE, a new version of PE, is interpreted as distance to white noise, which shows a reverse trend to PE and has better stability than PE. In this paper, three kinds of ship-radiated noise (SN signal are decomposed by VMD algorithm, and a series of intrinsic mode functions (IMF are obtained. The NPEs of all the IMFs are calculated, the noise IMFs are screened out according to the value of NPE, and the process of denoising can be realized by reconstructing the rest of IMFs. Then the reconstructed SN signal is decomposed by VMD algorithm again, and one IMF containing the most dominant information is chosen to represent the original SN signal. Finally, NPE of the chosen IMF is calculated as a new complexity feature, which constitutes the input of the support vector machine (SVM for pattern recognition of SN. Compared with the existing denoising algorithms and feature extraction algorithms, the effectiveness of proposed algorithms is validated using the numerical simulation signal and the different kinds of SN signal.

  6. Submarine Information Organization and Prioritization and Submarine Officer of the Deck Experience

    Science.gov (United States)

    2004-07-12

    The Submarine Review, 58-64. Shobe, K. (2002, May). Information organization and modeling of the submarine officer of the deck and sonar operator...Technical Report 01Oct00 - 31Sep02 SUBMARINE INFORMATION ORGANIZATION AND PRIORITIZATION AND SUBMARINE OFFICER OF THE DECK EXPERIENCE 51001 1) Katharine K

  7. Enhancing Submarine Operational Relevance: A Leadership Challenge

    National Research Council Canada - National Science Library

    Daigle, Jr, Michael J

    2008-01-01

    .... This vision of submarine operations must change. As the military continues to shift to operations focused on joint capabilities, the submarine force must break from the closed, protective, and risk averse culture of its past and push forward...

  8. Submarine silicic volcanism: Processes and products

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.

    The occurrence of submarine silicic volcanics is rare at the mid-oceanic ridges, abyssal depths, seamounts and fracture zones. Hydrothermal processes are active in submarine silicic environments and are associated with host ores of Cu, Au, Ag, Pb...

  9. North American Submarine Cable Association (NASCA) Submarine Cables

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data show the locations of in-service and out-of-service submarine cables that are owned by members of NASCA and located in U.S. territorial waters. More...

  10. Coincident bursts of auroral kilometric radiation and VLF emissions associted with a type 3 solar radio noise event

    Science.gov (United States)

    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.

  11. Design and performances of a low-noise and radiation-hardened readout ASIC for CdZnTe detectors

    Science.gov (United States)

    Bo, Gan; Tingcun, Wei; Wu, Gao; Yongcai, Hu

    2016-06-01

    In this paper, we present the design and performances of a low-noise and radiation-hardened front-end readout application specific integrated circuit (ASIC) dedicated to CdZnTe detectors for a hard X-ray imager in space applications. The readout channel is comprised of a charge sensitive amplifier, a CR-RC shaping amplifier, an analog output buffer, a fast shaper, and a discriminator. An 8-channel prototype ASIC is designed and fabricated in TSMC 0.35-μm mixed-signal CMOS technology, the die size of the prototype chip is 2.2 × 2.2 mm2. The input energy range is from 5 to 350 keV. For this 8-channel prototype ASIC, the measured electrical characteristics are as follows: the overall gain of the readout channel is 210 V/pC, the linearity error is less than 2%, the crosstalk is less than 0.36%, The equivalent noise charge of a typical channel is 52.9 e- at zero farad plus 8.2 e- per picofarad, and the power consumption is less than 2.4 mW/channel. Through the measurement together with a CdZnTe detector, the energy resolution is 5.9% at the 59.5-keV line under the irradiation of the radioactive source 241Am. The radiation effect experiments show that the proposed ASIC can resist the total ionization dose (TID) irradiation of higher than 200 krad(Si). Project supported by the National Key Scientific Instrument and Equipment Development Project (No. 2011YQ040082), the National Natural Science Foundation of China (Nos. 11475136, 11575144, 61176094), and the Shaanxi Natural Science Foundation of China (No. 2015JM1016).

  12. Study on serum metabonomics of rats exposed to low-dose ionizing radiation, carbon monoxide, benzene and noise

    Directory of Open Access Journals (Sweden)

    Qing-rong WANG

    2015-07-01

    Full Text Available Objective To investigate the combined effects of low-dose ionizing radiation, carbon monoxide, benzene and noise on serum metabolites and the mechanism of injury induced by these complex environmental factors in rats. Methods  Sixteen adult SD rats were randomly divided into control group and exposed group (8 each. The exposed group received the combined effect every day for 7 days. At the end of experiment, sera were collected from the abdominal aorta of rats. The metabolic fingerprint of serum was obtained by 1H nuclear magnetic resonance (1H NMR spectroscopy and determined with pattern recognition techniques of principal component analysis (PCA and orthogonal signal correction-partial least squares (OSC-PLS. The similarities and differences in metabolic profiles between two groups were visualized by SIMCA-P software. Results The rat serum 1H NMR spectra revealed different metabolic spectra between the control group and exposed group. The OSC-PLS plots of the serum samples presented respectively marked clustering between the two groups. Compared with the control group, the contents of lipid, high density lipoprotein, glycine/glucose, N-acetyl glycoprotein 1, N-acetyl glycoprotein 2, phosphatidyl choline and unsaturated fatty acid increased, while those of lactic acid, threonine/lipid, alanine, creatine, glycerylphosphorylcholine/ trimethylamine oxide, low density lipoprotein/high density lipoprotein, low density lipoprotein, very low density lipoprotein/ low density lipoprotein, very low density lipoprotein and saturated fatty acid decreased. Conclusions Combination of low-dose ionizing radiation, carbon monoxide, benzene and noise could induce changes of serum metabolites in rats, involving in immune function, renal function and energy metabolism. The NMR-based-metabonomics method has potential of application in research on combined biological effects of the complex environmental factors. DOI: 10.11855/j.issn.0577-7402.2015.07.09

  13. Numerical investigation of noise generation and radiation from an existing modular expansion joint between prestressed concrete bridges

    Science.gov (United States)

    Ghimire, Jhabindra P.; Matsumoto, Yasunao; Yamaguchi, Hiroki; Kurahashi, Itsumi

    2009-11-01

    Noise generated from modular bridge expansion joints during vehicle pass-bys has caused localized environmental problems in Japan and elsewhere. The objective of this study was to understand the mechanism of noise generation and radiation from a modular expansion joint installed in an expressway bridge. A numerical investigation was conducted in order to understand the dynamic characteristics of the joint and the acoustic characteristics of the sound field around the joint that measurements cannot reveal due to their limitations, such as the number of measurement locations that are required. Vibro-acoustic analysis was conducted by using the finite element method-boundary element method (FEM-BEM) approach: dynamic analysis of the joint was carried out by FEM and the sound fields inside the cavity located beneath the joint and outside of the cavity were analyzed by BEM. It was concluded that dominant frequency components in the sound pressure inside the cavity were due to excitation of the structural modes of the joint and/or acoustic modes of the cavity. For the expansion joint investigated, the sound field farther than about 35 m from the joint-cavity center could be considered as far field in the range of 50-400 Hz.

  14. Submarine geothermal resources

    Science.gov (United States)

    Williams, D.L.

    1976-01-01

    Approximately 20% of the earth's heat loss (or 2 ?? 1012 cal/s) is released through 1% of the earth's surface area and takes the form of hydrothermal discharge from young (Pleistocene or younger) rocks adjacent to active seafloor-spreading centers and submarine volcanic areas. This amount is roughly equivalent to man's present gross energy consumption rate. A sub-seafloor geothermal reservoir, to be exploitable under future economic conditions, will have to be hot, porous, permeable, large, shallow, and near an energy-deficient, populated land mass. Furthermore, the energy must be recoverable using technology achievable at a competitive cost and numerous environmental, legal and institutional problems will have to be overcome. The highest-temperature reservoirs should be found adjacent to the zones of the seafloor extension or volcanism that are subject to high sedimentation rates. The relatively impermeable sediments reduce hydrothermal-discharge flow rates, forcing the heat to be either conducted away or released by high-temperature fluids, both of which lead to reservoir temperatures that can exceed 300??C. There is evidence that the oceanic crust is quite permeable and porous and that it was amenable to deep (3-5 km) penetration by seawater at least some time in the early stages of its evolution. Most of the heat escapes far from land, but there are notable exceptions. For example, in parts of the Gulf of California, thermal gradients in the bottom sediments exceed 1??C/m. In the coastal areas of the Gulf of California, where electricity and fresh water are at a premium, this potential resource lies in shallow water (< 200 m) and within sight of land. Other interesting areas include the Sea of Japan, the Sea of Okhotsk and the Andaman Sea along the margins of the western Pacific, the Tyrrhenian Sea west of Italy, and the southern California borderland and west flank of the Juan de Fuca Ridge off the west coast of the United States. Many questions remain to be

  15. Underwater and Dive Station Work-Site Noise Surveys

    National Research Council Canada - National Science Library

    Wolgemuth, Keith S; Cudahy, Edward A; Schwaller, Derek W

    2008-01-01

    Previous work performed by the Naval Submarine Medical Research Laboratory (NSMRL) had developed in-water permissible continuous noise exposure guidance Work performed by the Navy Experimental Diving Unit...

  16. Submarine canyons off Madras Coast

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    Submarine canyons off the coast of Madras, Tamil Nadu, India were studied during cruise of @iINS Kistna@@ as part of the IIOE programme They consist of hill-like projections and V-shaped valleys Their other features are also reported...

  17. Bioaerosols, Noise, and Ultraviolet Radiation Exposures for Municipal Solid Waste Handlers

    Science.gov (United States)

    Ncube, Esper Jacobeth; Voyi, Kuku

    2017-01-01

    Few studies have investigated the occupational hazards of municipal solid waste workers, particularly in developing countries. Resultantly these workers are currently exposed to unknown and unabated occupational hazards that may endanger their health. We determined municipal solid waste workers' work related hazards and associated adverse health endpoints. A multifaceted approach was utilised comprising bioaerosols sampling, occupational noise, thermal conditions measurement, and field based waste compositional analysis. Results from our current study showed highest exposure concentrations for Gram-negative bacteria (6.8 × 103 cfu/m3) and fungi (12.8 × 103 cfu/m3), in the truck cabins. Significant proportions of toxic, infectious, and surgical waste were observed. Conclusively, municipal solid waste workers are exposed to diverse work related risks requiring urgent sound interventions. A framework for assessing occupational risks of these workers must prioritize performance of exposure assessment with regard to the physical, biological, and chemical hazards of the job. PMID:28167969

  18. Flame cutting using natural gas, propane and acetylene. Working conditions. Air pollution. Optical radiation. Noise. Flammeskaering med naturgas, propan og acetylen. Arbejdsmiljoeundersoegelser: Luftforurening, optisk straaling, stoej

    Energy Technology Data Exchange (ETDEWEB)

    Beck Hansen, E.; Eriksen, P.; Skotte, J.

    1987-01-01

    An investigation was made of the indoor air pollution, optical radiation and noise pollution resulting from the use of flame cutters fueled with natural gas, propane and acetylene. There is no significant variation in the amounts of pollutive emission measured from these gases, though natural gas gave a lesser quantity of gas and carbon monoxide emission than did both propane and acetylene. Smoke formation constituted 96% of the total indoor air pollution measured. The initial free burning warming-up flame gave a very significant nitrous gas and carbon monoxide emission in relation to amounts emitted during the cutting process. The influence of utilization of natural gas flame cutters on the amount of optical radiation is negligible, and 85-90% of radiation is infrared. Radiation answers to a temperature radiation with 2380 K, for all three gas types and ultraviolet radiation constitutes of only 1% of the total amount. The amount of glare equals that given out by a 40 W electric bulb. It is recommended that the operator wears normal eye shields which will also be sufficient to protect him/her from all tyes of optical radiation. There is little difference in the amount of noise pollution produced by the three gas forms. Noise proportions vary according to the different processes involved, it is highest in the warming-upstage. Measurements are, at a distance of 0.5m distance 89-96 dB(A) (manual cutting), and where the distance is 2m, 79-86 dB(A) (machine cutting) depending on the size of the nozzle of the cutting instrument. (AB).

  19. SCICEX: Submarine Arctic Science Program, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Submarine Arctic Science Program, SCICEX, is a federal interagency collaboration among the operational Navy, research agencies, and the marine research community...

  20. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another

  1. Are tilt measurements useful in detecting tsunamigenic submarine landslides?

    Science.gov (United States)

    Brune, Sascha; Babeyko, Andrey Y.; Sobolev, Stephan V.

    2009-06-01

    Large submarine landslides can generate dangerous tsunamis. Because of their long-period signal, detection of landslides by common seismological methods is difficult. Here we suggest a method of detecting submarine landslides by using an array of land-based tiltmeters. The displacement of a large volume of sediments during landsliding produces a detectable elastic response of the lithosphere. We propose a technique to calculate this response and to invert for tsunami relevant parameters like slide location, volume, and velocity. We exemplify our method by applying it to the Storegga slide west of Norway and other tsunamigenic landslide events. The parameter which can be most robustly estimated from tiltmeter array measurements is the product of slide volume and its velocity (slide tsunamigenic potential). This parameter also controls the amplitude of the generated tsunami wave. The inversion accuracy of this parameter and the estimated tsunami height near the coast depends on the noise level of tiltmeter measurements, distance of the tiltmeters from the slide, and slide tsunamigenic potential itself. The tsunamigenic potential of the most dangerous slides like Storegga can be estimated well by tiltmeters at the coast if the effective noise level does not exceed 50 nrad.

  2. Submarine landslides: advances and challenges

    Science.gov (United States)

    Locat, Jacques; Lee, Homa J.

    2002-01-01

    Due to the recent development of well-integrated surveying techniques of the sea floor, significant improvements were achieved in mapping and describing the morphology and architecture of submarine mass movements. Except for the occurrence of turbidity currents, the aquatic environment (marine and fresh water) experiences the same type of mass failure as that found on land. Submarine mass movements, however, can have run-out distances in excess of 100 km, so their impact on any offshore activity needs to be integrated over a wide area. This great mobility of submarinemass movements is still not very well understood, particularly for cases like the far-reaching debris flows mapped on the Mississippi Fan and the large submarine rock avalanches found around many volcanic islands. A major challenge ahead is the integration of mass movement mechanics in an appropriate evaluation of the hazard so that proper risk assessment methodologies can be developed and implemented for various human activities offshore, including the development of natural resources and the establishment of reliable communication corridors. Key words : submarine slides, hazards, risk assessment, morphology, mobility, tsunami. Le dveloppement rcent de techniques de levs hydrograhiques pour les fonds marins nous a permis d'atteindre une qualit ingale dans la cartographie et la description des glissements sous marins. l'exception des courants de turbidit, on retrouve dans le domaine aquatique les mmes types de mouvements de terrain que sur terre. Par contre, les glissements sous-marins peuvent atteindre des distances excdant 100 km de telle sorte que leur impact sur les activits offshore doit tre pris en compte sur degrandes tendues. La grande mobilit des glissements sous-marins n'est pas encore bien comprise, comme pour le cas des coules dedbris cartographies sur le cne du Mississippi ainsi que pour les grandes avalanches rocheuses sous-marines retrouves au pourtour des les volcaniques. Un dfi majeur

  3. Similarities between rivers and submarine channels

    Science.gov (United States)

    Balcerak, Ernie

    2013-02-01

    Scientists have long known that the width and depth of rivers follows a power law relationship with discharge. They have also noticed that submarine channels appear to be similar to terrestrial rivers, but there have not been many systematic comparisons of the relationships between submarine channel morphology and discharge. Konsoer et al. compared the width, depth, and slope of 177 submarine channels to those of 231 river cross sections. They found that submarine channels are up to an order of magnitude wider and deeper than the largest terrestrial rivers, but they exhibit a similar power law relationship between width and depth. For submarine channels that were similar in size to rivers, the authors found that submarine channels tend to be 1 to 2 orders of magnitude steeper than rivers. The authors also inferred values for sediment concentration in the turbidity currents in the channels and combined this with estimated mean flow velocities to look for a relationship between discharge and morphology in the channels. They found that like rivers, the width and depth of the submarine channels follow a power law scaling with discharge. (Journal of Geophysical Research-Earth Surface, doi:10.1029/2012JF002422, 2013)

  4. Noise suppression by noise

    OpenAIRE

    Vilar, J. M. G.; Rubí Capaceti, José Miguel

    2001-01-01

    We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.

  5. Some calculated effects of non-uniform inflow on the radiated noise of a large wind turbine

    Science.gov (United States)

    Greene, G. C.; Hubbard, H. H.

    1980-01-01

    Far field computations were performed for a large wind turbine to evaluate the effects of non-uniform aerodynamic loading over the rotor disk. A modified version of the Farassat/Nystrom propeller noise prediction program was applied to account for the variations in loading due to inflow interruption by the upstream support tower. The computations indicate that for the uniform inflow case, relatively low noise levels are generated and the first rotational harmonic dominated the spectrum. For cases representing wake flow deficiences due to the tower structure, subtantially increased noise levels for all harmonics are indicated, the greatest increases being associated with the higher order harmonics.

  6. A Proposed General Method for Parameter Estimation of Noise Corrupted Oscillator Systems

    OpenAIRE

    OBrien Jr, Francis J.; Johnnie, Nathan; Maloney, Susan; Ross, Aimee

    2012-01-01

    This paper provides a proposed means to estimate parameters of noise corrupted oscillator systems. An application for a submarine combat control systems (CCS) rack is described as exemplary of the method.

  7. Calciclastic submarine fans: An integrated overview

    Science.gov (United States)

    Payros, Aitor; Pujalte, Victoriano

    2008-01-01

    Calciclastic submarine fans are rare in the stratigraphic record and no bona fide present-day analogue has been described to date. Possibly because of that, and although calciclastic submarine fans have long intrigued deep-water carbonate sedimentologists, they have largely been overlooked by the academic and industrial communities. To fill this gap we have compiled and critically reviewed the existing sedimentological literature on calciclastic submarine fans, thus offering an updated view of this type of carbonate slope sedimentary system. Calciclastic submarine fans range in length from just a few to more than 100 km. Three different types can be distinguished: (1) Coarse-grained, small-sized (depression associated with tectonic structures, an inherited topography, or large-scale mass failures.

  8. Russia's Submarine Force: Determinants and Prospects

    National Research Council Canada - National Science Library

    Tully, John

    2001-01-01

    ... the determinants of these events, The Russian Federation inherited a huge submarine fleet from the Soviet Union, Due to the changing conditions in the world and in Russia, its future status is in doubt...

  9. SSN 774 Virginia Class Submarine (SSN 774)

    Science.gov (United States)

    2015-12-01

    Report: The VIRGINIA Class Submarine Program continues to deliver submarines within cost, ahead of schedule , with improved quality and with...baseline schedule threshold set ten years earlier, in 1994. June 20, 2006: USS TEXAS, which was essentially the second lead ship of the class , is the first...factored for the VIRGINIA Class based on weight. Public and private shipyard data was used, as well as the maintenance schedule provided in the CARD, Rev E

  10. Submarine landslides: processes, triggers and hazard prediction.

    Science.gov (United States)

    Masson, D G; Harbitz, C B; Wynn, R B; Pedersen, G; Løvholt, F

    2006-08-15

    Huge landslides, mobilizing hundreds to thousands of km(3) of sediment and rock are ubiquitous in submarine settings ranging from the steepest volcanic island slopes to the gentlest muddy slopes of submarine deltas. Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential. The major hazards related to submarine landslides include destruction of seabed infrastructure, collapse of coastal areas into the sea and landslide-generated tsunamis. Most submarine slopes are inherently stable. Elevated pore pressures (leading to decreased frictional resistance to sliding) and specific weak layers within stratified sequences appear to be the key factors influencing landslide occurrence. Elevated pore pressures can result from normal depositional processes or from transient processes such as earthquake shaking; historical evidence suggests that the majority of large submarine landslides are triggered by earthquakes. Because of their tsunamigenic potential, ocean-island flank collapses and rockslides in fjords have been identified as the most dangerous of all landslide related hazards. Published models of ocean-island landslides mainly examine 'worst-case scenarios' that have a low probability of occurrence. Areas prone to submarine landsliding are relatively easy to identify, but we are still some way from being able to forecast individual events with precision. Monitoring of critical areas where landslides might be imminent and modelling landslide consequences so that appropriate mitigation strategies can be developed would appear to be areas where advances on current practice are possible.

  11. Focused sound from three-dimensional sound propagation effects over a submarine canyon.

    Science.gov (United States)

    Chiu, Linus Y S; Lin, Ying-Tsong; Chen, Chi-Fang; Duda, Timothy F; Calder, Brian

    2011-06-01

    Ship noise data reveal an intensification of the near-surface sound field over a submarine canyon. Numerical modeling of sound propagation is used to study the effect. The noise data were collected during an ocean acoustic and physical oceanography experiment northeast of Taiwan in 2009. In situ measurements of water sound-speed profiles and a database of high-resolution bathymetry are used in the modeling study. The model results suggest that the intensification is caused by three-dimensional sound focusing by the concave canyon seafloor. Uncertainties in the model results from unsampled aspects of the environment are discussed. © 2011 Acoustical Society of America

  12. Numerical simulation of viscous flow and hydrodynamic noise in surface ship

    Directory of Open Access Journals (Sweden)

    YU Han

    2017-12-01

    Full Text Available [Objectives] The problem of noise caused by an unsteady flow field around a surface ship is a difficulty facing the stealth design of ship hulls, in which the existence of the free surface makes it different from submarine hydrodynamic noise calculation. To solve this problem,[Methods] the Volume of Fluid(VOF method and SST k-ω turbulence model are combined to simulate the unsteady flow field of the hull, and the free surface is given an air acoustic impedance to simulate the absorption boundary. The pulsating pressure of the hull surface is used as the source of the noise, and the underwater radiation noise of the surface ship is calculated with the acoustic finite element method.[Results] The results show high agreement with the experimental results and previous simulation results. The noise sources are mainly concentrated at the bow of the hull.[Conclusions] The results show that this calculation method can accurately simulate the flow field and sound field of a surface ship, and it can provides valuable reference for the acoustic stealth design of surface ships.

  13. Development of a compact radiation-hardened low-noise front-end readout ASIC for CZT-based hard X-ray imager

    Science.gov (United States)

    Gao, W.; Gan, B.; Li, X.; Wei, T.; Gao, D.; Hu, Y.

    2015-04-01

    In this paper, we present the development and performances of a radiation-hardened front-end readout application-specific integrated circuit (ASIC) dedicated to CZT detectors for a hard X-ray imager in space applications. The readout channel consists of a charge sensitive amplifier (CSA), a CR-RC shaper, a fast shaper, a discriminator and a driving buffer. With the additional digital filtering, the readout channel can achieve very low noise performances and low power dissipation. An eight-channel prototype ASIC is designed and fabricated in 0.35 μm CMOS process. The energy range of the detected X-rays is evaluated as 1.45 keV to 281 keV. The gain is larger than 100 mV/fC. The equivalent noise charge (ENC) of the ASIC is 53 e- at zero farad plus 10 e- per picofarad. The power dissipation is less than 4.4 mW/channel. Through the measurement with a CZT detector, the energy resolution is less than 3.45 keV (FWHM) under the irradiation of the radioactive source 241Am. The radiation effect experiments indicate that the proposed ASIC can resist the total ionization dose (TID) irradiation of higher than 200 krad (Si).

  14. A Study on Suppression of Electromagnetic Radiation Noise from Wireless Module in Millimeter-Wave Band by Using Alumina Containing Carbon Black

    Science.gov (United States)

    Takase, Yasuharu; Hashimoto, Osamu; Matsumoto, Kouta; Kumada, Taketo

    The unwanted electromagnetic(EM) radiation wave generated from the wireless module in millimeter-wave band used for the car radar influences some error and performance degradation of electronic equipments. In this paper, to reduce this unwanted EM wave, a optimal design to add the function of EM wave absorption to the lid for the module is examined. Therefore the alumina containing carbon black is used as a wave absorption material of the lid. The absorption of 20dB or more is obtained as a measured result with the cover added the EM wave absorption function in 60GHz. Furthermore, we analyzed the wireless module in millimeter-wave band by using the designed material for the lid. It is clarified that the radiation and the reflection electric power are greatly suppressed by loss electric power of the lid. Therefore, the effective data for suppressing the unwanted EM radiation noise from wireless module in millimeter-wave band can be provided.

  15. Geomorphic process fingerprints in submarine canyons

    Science.gov (United States)

    Brothers, Daniel S.; ten Brink, Uri S.; Andrews, Brian D.; Chaytor, Jason D.; Twichell, David C.

    2013-01-01

    Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A) are used to examine linkages between morphological domains and the generation and evolution of submarine sediment flows. For example, canyon reaches of the upper continental slope are characterized by steep, linear and/or convex longitudinal profiles, whereas reaches farther down canyon have distinctly concave longitudinal profiles. The transition between these geomorphic domains is inferred to represent the downslope transformation of debris flows into erosive, canyon-flushing turbidity flows. Over geologic timescales this process appears to leave behind a predictable geomorphic fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may be a proxy for the volume of sediment released during geomorphically significant failures along the upper continental slope. Focused studies of slope-sourced submarine canyons may provide new insights into the relationships between fine-scale canyon morphology and down-canyon changes in sediment flow dynamics.

  16. ESR dating of submarine hydrothermal activities using barite in sulfide deposition

    Science.gov (United States)

    Toyoda, S.; Fujiwara, T.; Ishibashi, J.; Isono, Y.; Uchida, A.; Takamasa, A.; Nakai, S.

    2012-12-01

    The temporal change of submarine hydrothermal activities has been an important issue in the aspect of the evolution of hydrothermal systems which is related with ore formation (Urabe, 1995) and biological systems sustained by the chemical species arising from hydrothermal activities (Macdonald et al., 1980). Determining the ages of the hydrothermal deposit will provide essential information on such studies. Dating methods using disequilibrium between radioisotopes such as U-Th method (e.g. You and Bickle, 1998), 226}Ra-{210Pb and 228}Ra-{228Th method (e.g. Noguchi et al., 2011) have been applied to date submarine hydrothermal deposits. ESR (electron spin resonance) dating method is commonly applied to fossil teeth, shells, and quartz of Quaternay period where the natural accumulated dose is obtained from the intensities of the ESR signals which are created by natural radiation. The natural dose is divided by the dose rate to the mineral/sample to deduce the age. Okumura et al., (2010) made the first practical application of ESR (electron spin resonance) dating technique to a sample of submarine hydrothermal barite (BaSO4) to obtain preliminary ages, where Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. Knowing that ESR dating of barite is promising, in this paper, we will present how we have investigated each factor that contributes ESR dating of barite in submarine hydrothermal sulfide deposition. (1) The best ESR condition for measuring the SO3- signal in barite is with the microwave power of 1mW and modulation amplitude of 0.1mT. (2) As results of heating experiments, the signal was found to be stable for the dating age range of several thousands. (3) 226Ra replacing Ba in barite is the source of the radiation. The amount of radioactive elements in sulfide mineral surrounding barite is negligible. (4) The external radiation from the sea water is negligible even in the submarine hydrothermal area where the radiation level is much

  17. Environmental monitoring of El Hierro Island submarine volcano, by combining low and high resolution satellite imagery

    Science.gov (United States)

    Eugenio, F.; Martin, J.; Marcello, J.; Fraile-Nuez, E.

    2014-06-01

    El Hierro Island, located at the Canary Islands Archipelago in the Atlantic coast of North Africa, has been rocked by thousands of tremors and earthquakes since July 2011. Finally, an underwater volcanic eruption started 300 m below sea level on October 10, 2011. Since then, regular multidisciplinary monitoring has been carried out in order to quantify the environmental impacts caused by the submarine eruption. Thanks to this natural tracer release, multisensorial satellite imagery obtained from MODIS and MERIS sensors have been processed to monitor the volcano activity and to provide information on the concentration of biological, chemical and physical marine parameters. Specifically, low resolution satellite estimations of optimal diffuse attenuation coefficient (Kd) and chlorophyll-a (Chl-a) concentration under these abnormal conditions have been assessed. These remote sensing data have played a fundamental role during field campaigns guiding the oceanographic vessel to the appropriate sampling areas. In addition, to analyze El Hierro submarine volcano area, WorldView-2 high resolution satellite spectral bands were atmospherically and deglinted processed prior to obtain a high-resolution optimal diffuse attenuation coefficient model. This novel algorithm was developed using a matchup data set with MERIS and MODIS data, in situ transmittances measurements and a seawater radiative transfer model. Multisensor and multitemporal imagery processed from satellite remote sensing sensors have demonstrated to be a powerful tool for monitoring the submarine volcanic activities, such as discolored seawater, floating material and volcanic plume, having shown the capabilities to improve the understanding of submarine volcanic processes.

  18. Phylogenetic signal detection from an ancient rapid radiation: Effects of noise reduction, long-branch attraction, and model selection in crown clade Apocynaceae.

    Science.gov (United States)

    Straub, Shannon C K; Moore, Michael J; Soltis, Pamela S; Soltis, Douglas E; Liston, Aaron; Livshultz, Tatyana

    2014-11-01

    Crown clade Apocynaceae comprise seven primary lineages of lianas, shrubs, and herbs with a diversity of pollen aggregation morphologies including monads, tetrads, and pollinia, making them an ideal group for investigating the evolution and function of pollen packaging. Traditional molecular systematic approaches utilizing small amounts of sequence data have failed to resolve relationships along the spine of the crown clade, a likely ancient rapid radiation. The previous best estimate of the phylogeny was a five-way polytomy, leaving ambiguous the homology of aggregated pollen in two major lineages, the Periplocoideae, which possess pollen tetrads, and the milkweeds (Secamonoideae plus Asclepiadoideae), which possess pollinia. To assess whether greatly increased character sampling would resolve these relationships, a plastome sequence data matrix was assembled for 13 taxa of Apocynaceae, including nine newly generated complete plastomes, one partial new plastome, and three previously reported plastomes, collectively representing all primary crown clade lineages and outgroups. The effects of phylogenetic noise, long-branch attraction, and model selection (linked versus unlinked branch lengths among data partitions) were evaluated in a hypothesis-testing framework based on Shimodaira-Hasegawa tests. Discrimination among alternative crown clade resolutions was affected by all three factors. Exclusion of the noisiest alignment positions and topologies influenced by long-branch attraction resulted in a trichotomy along the spine of the crown clade consisting of Rhabdadenia+the Asian clade, Baisseeae+milkweeds, and Periplocoideae+the New World clade. Parsimony reconstruction on all optimal topologies after noise exclusion unambiguously supports parallel evolution of aggregated pollen in Periplocoideae (tetrads) and milkweeds (pollinia). Our phylogenomic approach has greatly advanced the resolution of one of the most perplexing radiations in Apocynaceae, providing the

  19. Addressing submarine geohazards through scientific drilling

    Science.gov (United States)

    Camerlenghi, A.

    2009-04-01

    Natural submarine geohazards (earthquakes, volcanic eruptions, landslides, volcanic island flank collapses) are geological phenomena originating at or below the seafloor leading to a situation of risk for off-shore and on-shore structures and the coastal population. Addressing submarine geohazards means understanding their spatial and temporal variability, the pre-conditioning factors, their triggers, and the physical processes that control their evolution. Such scientific endeavour is nowadays considered by a large sector of the international scientific community as an obligation in order to contribute to the mitigation of the potentially destructive societal effects of submarine geohazards. The study of submarine geohazards requires a multi-disciplinary scientific approach: geohazards must be studied through their geological record; active processes must be monitored; geohazard evolution must be modelled. Ultimately, the information must be used for the assessment of vulnerability, risk analysis, and development of mitigation strategies. In contrast with the terrestrial environment, the oceanic environment is rather hostile to widespread and fast application of high-resolution remote sensing techniques, accessibility for visual inspection, sampling and installation of monitoring stations. Scientific Drilling through the IODP (including the related pre site-survey investigations, sampling, logging and in situ measurements capability, and as a platform for deployment of long term observatories at the surface and down-hole) can be viewed as the centre of gravity of an international, coordinated, multi-disciplinary scientific approach to address submarine geohazards. The IODP Initial Science Plan expiring in 2013 does not address openly geohazards among the program scientific objectives. Hazards are referred to mainly in relation to earthquakes and initiatives towards the understanding of seismogenesis. Notably, the only drilling initiative presently under way is the

  20. MVAC Submarine cable, impedance measurements and analysis

    DEFF Research Database (Denmark)

    Arentsen, Martin Trolle; Pedersen, Morten Virklund; Expethit, Adrian

    2017-01-01

    Due to environmental concerns an increase in off-shore windfarms has been observed in recent years, leading to an increased demand for three-core-wire-armoured submarine cables. However, the IEC Standard 60287 used to calculate the ampacity of these cables is widely recognized as being not accurate...

  1. German Submarine Offensives and South African Countermeasures

    African Journals Online (AJOL)

    Evert

    'Good Hunting': German Submarine Offensives and South African. Countermeasures off the South African Coast during the Second World. War, 1942-1945. Evert Kleynhans. •. Abstract .... wolf packs south, Dönitz had hoped to cause a diversionary effect whereby the Allies would be forced to split their defensive forces ...

  2. Submarine Telecommunication Cables in Disputed Maritime Areas

    NARCIS (Netherlands)

    van Logchem, Youri

    2014-01-01

    There are a considerable number of maritime areas where no boundary exists, or where a boundary is delimited only in part. This article deals with the issue of submarine telecommunication cables, which are sometimes placed on the seabed or buried in the subsoil of areas that are claimed by multiple

  3. Monitoring of the nuclear submarine Komsomolets

    Energy Technology Data Exchange (ETDEWEB)

    Heldal, Hilde E.; Flo, Janita K.; Liebig, Penny L. [Institute of Marine Research, P. O. Box 1870 Nordnes, N-5817 Bergen (Norway); Gaefvert, Torbjoern; Rudjord, Anne Liv [Norwegian Radiation Protection Authority, P.O. Box 55, N-1332 Oesteraas (Norway); Gwynn, Justin P. [Norwegian Radiation Protection Authority, The Fram Centre, N-9296 Tromsoe (Norway)

    2014-07-01

    The Soviet nuclear submarine Komsomolets sank on the 7 April 1989, 180 km southwest of Bear Island in the Norwegian Sea to a depth of about 1655 m. The submarine contains one nuclear reactor containing long-lived radionuclides such as cesium-137 ({sup 137}Cs) along with other fission and activation products, in addition to 2 mixed uranium/plutonium nuclear warheads containing weapons grade plutonium. Although several model studies have shown that a radioactive leakage from Komsomolets will have insignificant impact on fish and other marine organisms, there are still public concerns about the condition of the submarine and the potential for radioactive leakage. In order to document the contamination levels and to meet public concerns, monitoring of radioactive contamination in the area adjacent to the submarine has been ongoing since 1993. Samples of bottom seawater and sediments have been collected annually by the Institute of Marine Research (IMR) and have been analysed for {sup 137}Cs and plutonium-239,240 ({sup 239,240}Pu). So far, activity concentrations in the samples have been comparable to levels found in other samples from the Norwegian and Barents Seas. During sampling from R/V 'G. O. Sars' in April 2013, an area of about 1 km{sup 2} of the seabed around Komsomolets was mapped to precisely locate the submarine using a Kongsberg EM302 multibeam echo sounder, a Simrad EK60 single beam echo sounder and an Olex 3D bottom-mapping system. For sediment sampling, a Simrad MST342 mini-transponder was attached to a Smoegen box corer to allow for precise positioning of the corer. With the aid of the Kongsberg HiPAP (High Precision Acoustic Positioning) system, 4 box cores were collected around the submarine at a distance of 10 to 20 m. In addition, one box core was collected from a reference station about 100 m upstream of the submarine. Surface sediments and sediment cores were collected from the box cores taken at each sampling location. Sediment cores

  4. Chemical environments of submarine hydrothermal systems

    Science.gov (United States)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such

  5. Phase 1 Final Report: Titan Submarine

    Science.gov (United States)

    Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

    2015-01-01

    The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of

  6. Imaging deformation in submarine thrust belts using seismic attributes

    Science.gov (United States)

    Iacopini, David; Butler, Robert W. H.

    2011-02-01

    Uncertainty exists as to the patterns of deformation that develop within submarine thrust belts. This case study uses a large-scale gravity-driven fold-thrust structure as an analogue for submarine fold thrust systems in general. Seismic attribute analysis and mapping provide ways of identifying complex fault patterns and associated deformation that are otherwise unresolved in conventional amplitude displays. These methods are developed and applied to a 3D dataset and used to investigate the geometry, internal architecture and the nature of the low signal/noise incoherency and discontinuities observed on the km-scale. Semblance (coherency), curvatures and spectral decomposition were all computed and used as attributes. Collectively these define volumes within the seismic data where the signal is greatly reduced — features termed here "disturbance geobodies". The study shows that thrust faults that, on conventional amplitude displays appear to be simple and continuous, are likely to consist of complex arrays of anastamosing fault strands. Adjacent to these composite fault zones are greater volumes of deformed rocks (disturbance geobodies) across which there are only minor stratal offsets. Similarly volumes of high stratal curvature coincide with disturbance geobodies, again interpreted as zones of weak, distributed deformation. These relationships between narrow thrust faults and broader zones of deformation are broadly comparable to those observed in outcrops within exhumed thrust systems. Application of the seismic imaging techniques developed here will improve the understanding of the localization of deformation in sedimentary successions with important implications for predicting fluid flow within other deep water structures such as subduction accretion complexes.

  7. Radiation dose reduction using 100-kVp and a sinogram-affirmed iterative reconstruction algorithm in adolescent head CT: Impact on grey-white matter contrast and image noise.

    Science.gov (United States)

    Nagayama, Yasunori; Nakaura, Takeshi; Tsuji, Akinori; Urata, Joji; Furusawa, Mitsuhiro; Yuki, Hideaki; Hirarta, Kenichiro; Kidoh, Masafumi; Oda, Seitaro; Utsunomiya, Daisuke; Yamashita, Yasuyuki

    2017-07-01

    To retrospectively evaluate the image quality and radiation dose of 100-kVp scans with sinogram-affirmed iterative reconstruction (IR) for unenhanced head CT in adolescents. Sixty-nine patients aged 12-17 years underwent head CT under 120- (n = 34) or 100-kVp (n = 35) protocols. The 120-kVp images were reconstructed with filtered back-projection (FBP), 100-kVp images with FBP (100-kVp-F) and sinogram-affirmed IR (100-kVp-S). We compared the effective dose (ED), grey-white matter (GM-WM) contrast, image noise, and contrast-to-noise ratio (CNR) between protocols in supratentorial (ST) and posterior fossa (PS). We also assessed GM-WM contrast, image noise, sharpness, artifacts, and overall image quality on a four-point scale. ED was 46% lower with 100- than 120-kVp (p noise was lower, on 100-kVp-S than 120-kVp at ST (p noise in adolescent head CT. • 100-kVp head CT provides 46% radiation dose reduction compared with 120-kVp. • 100-kVp scanning improves subjective and objective GM-WM contrast. • Sinogram-affirmed IR decreases head CT image noise, especially in supratentorial region. • 100-kVp protocol with sinogram-affirmed IR is suited for adolescent head CT.

  8. Miocene Current-Modified Submarine Fans

    Science.gov (United States)

    Arce Perez, L. E.; Snedden, J.; Fisher, W. L.

    2016-12-01

    In the southwestern Gulf of Mexico, new and newly reprocessed seismic data has revealed a series of large bedforms, with set thicknesses of 130 to 250 meters. These exhibit hummocky, oblique and shingled to parallel seismic clinoform reflections. This seismic package has a paleowater depth of 450 meters. Those shingled seismic reflections in offshore east Mexico are interpreted as contourite drift deposits. These Miocene-age contourites may be related to strong ocean bottom currents that modified submarine fans and transported sediment to the north. Those contourites were identified on older seismic data, but are better imaged and interpreted on this new data. Plans are to map out and investigate the origin and extent of fans and contourites that extends over a large area of the Gulf of Mexico. In the Early Miocene several submarine fans systems were formed by the sediment input related to orogenic activity in Mexico. Submarine fan development persisted into the Middle Miocene due to continued uplift and erosion of the Mexican landmass. Initial, contourites are small and close proximity to the deep-water fan. In the Late Miocene time, contourite drift field reached its maximum extent in the Mexican deepwater area, anchored on its southern end by a submarine mound. This mounded submarine fan is located in the offshore northeast Veracruz and can be linked to increased uplift and erosion of the Trans-Mexican volcanic belt. In the Miocene-Pliocene, the large contourite drift begins to diminish in size and scale and is moribund by the Pliocene, with establishment of oceanic circulation similar to the present day. This research is important to understand more about the Gulf of Mexico and also for the Miocene timeframe that is a key phase in the earth's history. The role of the change in bottom water flow during progressive closure of the equatorial seaway separating North and South America will also be investigated.

  9. Psychological Implications for Submarine Display Design

    Science.gov (United States)

    2005-08-01

    This paper addresses a number of psychological issues pertaining to display design . We review the literature comparing 3-D and 2-D displays and...perceptual, cognitive and ecological factors that are relevant to display design for submarine environments. The Generative Transformational approach...to visual perception is outlined and the relevance of transformational theory to display design is discussed. The paper also discusses a number of

  10. A Lanchester model of submarine attack on a carrier battlegroup

    OpenAIRE

    Eagle, James N.

    1987-01-01

    A Lanchester model is developed for a battlegroup ASW engagement. Two variations are included. In the first, long-range missile firing submarines, short-range missile or torpedo firing submarines, and submarines firing only torpedoes distribute their attack uniformly over battlegroup escort ships and carriers. In the second variation, the attack is concentrated on the carriers. supported by the Naval War College http://archive.org/details/lanchestermodelo00eagl NA

  11. A High Signal-To-Noise Ultraviolet Spectrum of NGC 7469: New Support for Reprocessing of Continuum Radiation

    Science.gov (United States)

    Kriss, Gerard A.; Peterson, Bradley M.; Crenshaw, D. Michael; Zheng, Wei

    2000-01-01

    From 1996 June 10 to 1996 July 29, the International AGN Watch monitored the Seyfert 1 galaxy NGC 7469 using the International Ultraviolet Explorer, the Rossi X-Ray Timing Explorer, and a network of ground-based observatories. On 1996 June 18, in the midst of this intensive monitoring period, we obtained a high signal-to-noise snapshot of the UV spectrum from 1150 to 3300 A, using the Faint Object Spectrograph (FOS) on the Hubble Space Telescope. This spectrum allows us to disentangle the UV continuum more accurately from the broad wings of the emission lines, to identify clean continuum windows free of contaminating emission and absorption, and to deblend line complexes such as Ly(alpha) + N V, C IV + He II + O III], Si III] + C III], and Mg II + Fe II. Using the FOS spectrum as a template, we have fitted and extracted line and continuum fluxes from the IUE monitoring data. The cleaner continuum extractions c o n h the discovery of time delays between the different UV continuum bands by Wanders et al. Our new measurements show delays increasing with wavelength for continuum bands centered at 1485, 1740, and 1825 A, relative to 1315 A with delays of 0.09, 0.28, and 0.36 days, respectively. Like many other Seyfert I galaxies, the UV spectrum of NGC 7469 shows intrinsic, blue-shifted absorption in Ly(alpha), N V, and C IV. Soft X-ray absorption is also visible in archival ASCA X-ray spectra. The strength of the UV absorption, however, is not compatible with a single-zone model in which the same material absorbs both the UV and X-ray light. Similar to other Seyfert galaxies, such as NGC 3516, the UV-absorbing gas in NGC 7469 has a lower ionization parameter and column density than the X-ray-absorbing material. While the UV and X-ray absorption does not arise in the same material, the frequent occurrence of both associated UV absorption and X-ray warm absorbers in the same galaxies suggests that the gas supply for each has a common origin.

  12. Acoustic radiation of damped cylindrical shell with arbitrary thickness in the fluid field

    Science.gov (United States)

    Zhang, Jun-Jie; Li, Tian-Yun; Ye, Wen-Bing; Zhu, Xiang

    2010-12-01

    The insertion loss of acoustic radiation of damped cylindrical shell described by 3-D elasticity Navier equations under radial harmonic applied load in fluid is presented. The classical integral transform technique, potential theory and Lamè resolution are used to derive the solutions of Navier equations. The higher precision inversion computation is introduced to solve the linear equations. Comparing with acoustic radiation of one-layer cylindrical shell, the influence of thickness, mass density, dilatational wave loss factor and Young's modulus of damping material and circumferential mode number of the cylindrical shell on the insertion loss is concluded. The theoretical model in the paper can be used to deal with the arbitrary thickness and any frequency of the coated layer in dynamic problem. The conclusions may be of theoretical reference to the application of damping material to noise and vibration control of submarines and underwater pipes.

  13. Meta-Analysis of Data from the Submarine Ventilation Doctrine Test Program

    National Research Council Canada - National Science Library

    Hoover, J

    1998-01-01

    .... The Submarine Ventilation Doctrine Test Program was developed to address submarine-specific issues regarding the use of ventilation systems to control smoke and heat movement, maintain habitability...

  14. Noise prevention

    Science.gov (United States)

    Methods for noise abatement are discussed. Noise nuisance, types of noise (continuous, fluctuating, intermittent, pulsed), and types of noise abatement (absorption, vibration damping, isolation) are defined. Rockwool panels, industrial ceiling panels, baffles, acoustic foam panels, vibration dampers, acoustic mats, sandwich panels, isolating cabins and walls, ear protectors, and curtains are presented.

  15. North Sea submarine cable disruptions and fishing activity

    NARCIS (Netherlands)

    Hintzen, N.T.; Machiels, M.A.M.

    2014-01-01

    At the North Sea seafloor, numerous submarine cables are positioned that connect telecommunication networks between countries. Worldwide, human activities cause most of the cable disruptions with fisheries accounting for nearly half of all reported faults. Due to a recent increase of submarine cable

  16. The 1929 Grand Banks submarine landslide revisited

    Science.gov (United States)

    Schulten, Irena; Mosher, David C.; Krastel, Sebastian; Piper, David J. W.; Kienast, Markus

    2017-04-01

    On November 18th, 1929 a large submarine landslide occurred along the St. Pierre Slope of the southwestern Grand Banks of Newfoundland, as a result of a Mw 7.2 earthquake. This submarine landslide led to the first recognition of naturally-occurring submarine turbidity currents and is one of the few landslides known to have generated a tsunami. The event caused 28 causalities in Newfoundland and severe infrastructural damage. Earlier investigations of the area identified widely distributed shallow mass failures (15 - 20 m high escarpments), but no evidence of a larger headscarp. It is difficult to conceive, therefore, how this distributed shallow failure that rapidly evolved into a turbidity current would have generated a tsunami. It is hypothesised in this study that a deeper rooted sediment failure ( 500 m), involving faulting and mass-rotation, was involved in the sediment failure and this displacement generated the tsunami. In order to test this hypothesis, the volume and kinematics of the 1929 slope failure are analysed by means of recently acquired high resolution seismic reflection and multibeam swath bathymetry data, in addition to a significant volume of legacy data. The data allow determination of: 1) the dimension of the failure area, 2) the thickness and volume of failed sediment on St. Pierre Slope, 3) fault patterns and displacements, and 4) styles of sediment failure involved. Shallow (20 m high) sinuous escarpments and a number of faults are observed along the upper St. Pierre Slope (500 - 2 500 m water depth). The uppermost and largest of these escarpments shows association with a fault system. Preliminary results, therefore, indicate a complex sediment failure pattern along the St. Pierre Slope, possibly involving a deep-seated decollement and mobilization of a large volume of surficial sediment through retrogressive failure. Causes for the tsunami are yet to be determined.

  17. Deep water velocities and particle displacements induced by acoustic-gravity waves from submarine earthquakes

    Science.gov (United States)

    Oliveira, T. C. A.; Kadri, U.

    2016-02-01

    An uplift of the ocean bottom caused by a submarine earthquake can generate Acoustic-Gravity Waves (AGW), progressive compression-type waves that travel at near the speed of sound in water. The role of AGW for oceans hydrodynamics has recently became a topic of increasing scientific interest. Kadri [Deep ocean water transport by acoustic-gravity waves, J.Geo. Res. Oceans, 119, (2014)] showed theoretically that AGW can contribute to deep ocean currents and circulation. We analyze and simulate the fundamental AGW modes generated by a submarine earthquake. We consider the first five AGW modes and show that they may all induce comparable temporal variations in water particle velocities at different depths in regions far from the epicenter. Results of temporal variations of horizontal and vertical fluid parcel velocities induced by AGW confirm chaotic flow trajectories at different water depths. A realistic example based on the 2004 Indian Ocean earthquake shows that vertical water particle displacements of O(10-2 ) m can be generated at 1 Km depth in a 4 km water depth ocean. We show that the velocity field depends on the presence of the leading AGW modes. Each AGW mode becomes evanescent at a critical time, at which energy is transferred to the next higher modes. Consequently, the main pattern of the velocity field changes as the leading mode change. As an example, for a reference point located at 1000 Km from the epicenter, the first five AGW become evanescent after 1.6, 4.6, 7.7, 10.8 and 13.8 hours, respectively. Our analysis and simulations shed light on the spatio-temporal evolution of the deep water velocities and particle displacements induced by AGW that radiate during submarine earthquakes. Thus, this work is a contribution to understand the role of high moment magnitude submarine earthquakes in deep water mixing mechanism.

  18. Multivariable Control System Design for a Submarine,

    Science.gov (United States)

    1984-05-01

    perturbations applied to the nominal point were identical in all cases (see table 2.3). The comparisons show excellent correlation between the...Open Loop Singular Values for the 5 and 1S Knot Linear Modelo *~~* b % % V’ , * % ~ .%~ C 9 ~ V. --.- V. V.-.--.--46..- S. 77’ Model S20R5 20- 10- -0...without imparting a pitch angle to the submarine and provides an excellent example of both the usefulness of w(t) as a state variable and the

  19. Hydrogen isotope systematics of submarine basalts

    Science.gov (United States)

    Kyser, T.K.; O'Neil, J.R.

    1984-01-01

    The D/H ratios and water contents in fresh submarine basalts from the Mid-Atlantic Ridge, the East Pacific Rise, and Hawaii indicate that the primary D/H ratios of many submarine lavas have been altered by processes including (1) outgassing, (2) addition of seawater at magmatic temperature, and (3) low-temperature hydration of glass. Decreases in ??D and H2O+ from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between ??D and H2O+ in basalts from the Galapagos Rise and the FAMOUS Area are attributed to outgassing of CH4 and H2. A good correlation between ??D values and H2O is observed in a suite of submarine tholeiites dredged from the Kilauea East Rift Zone where seawater (added directly to the magma), affected only the isotopic compositions of hydrogen and argon. Analyses of some glassy rims indicate that the outer millimeter of the glass can undergo lowtemperature hydration by hydroxyl groups having ??D values as low as -100. ??D values vary with H2O contents of subaerial transitional basalts from Molokai, Hawaii, and subaerial alkali basalts from the Society Islands, indicating that the primary ??D values were similar to those of submarine lavas. Extrapolations to possible unaltered ??D values and H2O contents indicate that the primary ??D values of most thoteiite and alkali basalts are near -80 ?? 5: the weight percentages of water are variable, 0.15-0.35 for MOR tholeiites, about 0.25 for Hawaiian tholeiites, and up to 1.1 for alkali basalts. The primary ??D values of -80 for most basalts are comparable to those measured for deep-seated phlogopites. These results indicate that hydrogen, in marked contrast to other elements such as Sr, Nd, Pb, and O, has a uniform isotopic composition in the mantle. This uniformity is best explained by the presence of a homogeneous reservoir of hydrogen that has existed in the mantle since the very early history of the Earth. ?? 1984.

  20. Flow dynamics around downwelling submarine canyons

    Directory of Open Access Journals (Sweden)

    J. M. Spurgin

    2014-10-01

    Full Text Available Flow dynamics around a downwelling submarine canyon were analysed with the Massachusetts Institute of Technology general circulation model. Blanes Canyon (northwestern Mediterranean was used for topographic and initial forcing conditions. Fourteen scenarios were modelled with varying forcing conditions. Rossby and Burger numbers were used to determine the significance of Coriolis acceleration and stratification (respectively and their impacts on flow dynamics. A new non-dimensional parameter (χ was introduced to determine the significance of vertical variations in stratification. Some simulations do see brief periods of upwards displacement of water during the 10-day model period; however, the presence of the submarine canyon is found to enhance downwards advection of density in all model scenarios. High Burger numbers lead to negative vorticity and a trapped anticyclonic eddy within the canyon, as well as an increased density anomaly. Low Burger numbers lead to positive vorticity, cyclonic circulation, and weaker density anomalies. Vertical variations in stratification affect zonal jet placement. Under the same forcing conditions, the zonal jet is pushed offshore in more uniformly stratified domains. The offshore jet location generates upwards density advection away from the canyon, while onshore jets generate downwards density advection everywhere within the model domain. Increasing Rossby values across the canyon axis, as well as decreasing Burger values, increase negative vertical flux at shelf break depth (150 m. Increasing Rossby numbers lead to stronger downwards advection of a passive tracer (nitrate, as well as stronger vorticity within the canyon. Results from previous studies are explained within this new dynamic framework.

  1. Submarine Tailings Disposal (STD—A Review

    Directory of Open Access Journals (Sweden)

    Bernhard Dold

    2014-07-01

    Full Text Available The mining industry is a fundamental industry involved in the development of modern society, but is also the world’s largest waste producer. This role will be enhanced in the future, because ore grades are generally decreasing, thus leading to increases in the waste/metal production ratio. Mine wastes deposited on-land in so-called tailings dams, impoundments or waste-dumps have several associated environmental issues that need to be addressed (e.g., acid mine drainage formation due to sulphide oxidation, geotechnical stability, among others, and social concerns due to land use during mining. The mining industry recognizes these concerns and is searching for waste management alternatives for the future. One option used in the past was the marine shore or shallow submarine deposition of this waste material in some parts of the world. After the occurrence of some severe environmental pollution, today the deposition in the deep sea (under constant reducing conditions is seen as a new, more secure option, due to the general thought that sulphide minerals are geochemically stable under the reduced conditions prevailing in the deep marine environment. This review highlights the mineralogical and geochemical issues (e.g., solubility of sulphides in seawater; reductive dissolution of oxide minerals under reducing conditions, which have to be considered when evaluating whether submarine tailings disposal is a suitable alternative for mine waste.

  2. Submarine melt rates under Greenland's ice tongues

    Science.gov (United States)

    Wilson, Nat; Straneo, Fiametta; Heimbach, Patrick; Cenedese, Claudia

    2017-04-01

    The few remaining ice tongues (ice-shelf like extensions) of Greenland's glaciers are undergoing rapid changes with potential implications for the stability of the ice sheet. Submarine melting is recognized as a major contributor to mass loss, yet the magnitude and spatial distribution of melt are poorly known or understood. Here, we use high resolution satellite imagery to infer the magnitude and spatial variability of melt rates under Greenland's largest remaining ice tongues: Ryder Glacier, Petermann Glacier and Nioghalvfjerdsbræ (79 North Glacier). We find that submarine plus aerial melt approximately balance the ice flux from the grounded ice sheet for the first two while at Nioghalvfjerdsbræ the total melt flux exceeds the inflow of ice indicating thinning of the ice tongue. We also show that melt rates under the ice tongues vary considerably, exceeding 60 m yr-1 near the grounding zone and decaying rapidly downstream. Channels, likely originating from upstream subglacial channels, give rise to large melt variations across the ice tongues. Using derived melt rates, we test simplified melt parameterizations appropriate for ice sheet models and find the best agreement with those that incorporate ice tongue geometry in the form of depth and slope.

  3. Environmental assessment of submarine power cables

    Energy Technology Data Exchange (ETDEWEB)

    Isus, Daniel; Martinez, Juan D. [Grupo General Cable Sistemas, S.A., 08560-Manlleu, Barcelona (Spain); Arteche, Amaya; Del Rio, Carmen; Madina, Virginia [Tecnalia Research and Innovation, 20009 San Sebastian (Spain)

    2011-03-15

    Extensive analyses conducted by the European Community revealed that offshore wind energy have relatively benign effects on the marine environment by comparison to other forms of electric power generation [1]. However, the materials employed in offshore wind power farms suffer major changes to be confined to the marine environment at extreme conditions: saline medium, hydrostatic pressure... which can produce an important corrosion effect. This phenomenon can affect on the one hand, to the material from the structural viewpoint and on the other hand, to the marine environment. In this sense, to better understand the environmental impacts of generating electricity from offshore wind energy, this study evaluated the life cycle assessment for some new designs of submarine power cables developed by General Cable. To achieve this goal, three approaches have been carried out: leaching tests, eco-toxicity tests and Life Cycle Assessment (LCA) methodologies. All of them are aimed to obtaining quantitative data for environmental assessment of selected submarine cables. LCA is a method used to assess environmental aspects and potential impacts of a product or activity. LCA does not include financial and social factors, which means that the results of an LCA cannot exclusively form the basis for assessment of a product's sustainability. Leaching tests results allowed to conclude that pH of seawater did not significantly changed by the presence of submarine three-core cables. Although, it was slightly higher in case of broken cable, pH values were nearly equals. Concerning to the heavy metals which could migrate to the aquatic medium, there were significant differences in both scenarios. The leaching of zinc is the major environmental concern during undersea operation of undamaged cables whereas the fully sectioned three-core cable produced the migration of significant quantities of copper and iron apart from the zinc migrated from the galvanized steel. Thus, the tar

  4. What threat do turbidity currents and submarine landslides pose to submarine telecommunications cable infrastructure?

    Science.gov (United States)

    Clare, Michael; Pope, Edward; Talling, Peter; Hunt, James; Carter, Lionel

    2016-04-01

    The global economy relies on uninterrupted usage of a network of telecommunication cables on the seafloor. These submarine cables carry ~99% of all trans-oceanic digital data and voice communications traffic worldwide, as they have far greater bandwidth than satellites. Over 9 million SWIFT banks transfers alone were made using these cables in 2004, totalling 7.4 trillion of transactions per day between 208 countries, which grew to 15 million SWIFT bank transactions last year. We outline the challenge of why, how often, and where seafloor cables are broken by natural causes; primarily subsea landslides and sediment flows (turbidity currents and also debris flows and hyperpycnal flows). These slides and flows can be very destructive. As an example, a sediment flow in 1929 travelled up to 19 m/s and broke 11 cables in the NE Atlantic, running out for ~800 km to the abyssal ocean. The 2006 Pingtung earthquake triggered a sediment flow that broke 22 cables offshore Taiwan over a distance of 450 km. Here, we present initial results from the first statistical analysis of a global database of cable breaks and causes. We first investigate the controls on frequency of submarine cable breaks in different environmental and geological settings worldwide. We assess which types of earthquake pose a significant threat to submarine cable networks. Meteorological events, such as hurricanes and typhoons, pose a significant threat to submarine cable networks, so we also discuss the potential impacts of future climate change on the frequency of such hazards. We then go on to ask what are the physical impacts of submarine sediment flows on submerged cables? A striking observation from past cable breaks is sometimes cables remain unbroken, whilst adjacent cables are severed (and record powerful flows travelling at up to 6 m/s). Why are some cables broken, but neighbouring cables remain intact? We provide some explanations for this question, and outline the need for future in

  5. Radiation dose reduction using 100-kVp and a sinogram-affirmed iterative reconstruction algorithm in adolescent head CT: Impact on grey-white matter contrast and image noise

    Energy Technology Data Exchange (ETDEWEB)

    Nagayama, Yasunori [Kumamoto City Hospital, Department of Radiology, Kumamoto (Japan); Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Nakaura, Takeshi; Yuki, Hideaki; Hirarta, Kenichiro; Kidoh, Masafumi; Oda, Seitaro; Utsunomiya, Daisuke; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Tsuji, Akinori; Urata, Joji; Furusawa, Mitsuhiro [Kumamoto City Hospital, Department of Radiology, Kumamoto (Japan)

    2017-07-15

    To retrospectively evaluate the image quality and radiation dose of 100-kVp scans with sinogram-affirmed iterative reconstruction (IR) for unenhanced head CT in adolescents. Sixty-nine patients aged 12-17 years underwent head CT under 120- (n = 34) or 100-kVp (n = 35) protocols. The 120-kVp images were reconstructed with filtered back-projection (FBP), 100-kVp images with FBP (100-kVp-F) and sinogram-affirmed IR (100-kVp-S). We compared the effective dose (ED), grey-white matter (GM-WM) contrast, image noise, and contrast-to-noise ratio (CNR) between protocols in supratentorial (ST) and posterior fossa (PS). We also assessed GM-WM contrast, image noise, sharpness, artifacts, and overall image quality on a four-point scale. ED was 46% lower with 100- than 120-kVp (p < 0.001). GM-WM contrast was higher, and image noise was lower, on 100-kVp-S than 120-kVp at ST (p < 0.001). CNR of 100-kVp-S was higher than of 120-kVp (p < 0.001). GM-WM contrast of 100-kVp-S was subjectively rated as better than of 120-kVp (p < 0.001). There were no significant differences in the other criteria between 100-kVp-S and 120-kVp (p = 0.072-0.966). The 100-kVp with sinogram-affirmed IR facilitated dramatic radiation reduction and better GM-WM contrast without increasing image noise in adolescent head CT. (orig.)

  6. NESTOR - Neutrino Extended Submarine Telescope with Oceanographic Research

    CERN Document Server

    2002-01-01

    {\\bf NESTOR} is a deep-sea neutrino telescope that is being deployed in the Mediterranean off the south-west coast of the Peleponnese in Greece. Neutrinos, when they interact in the earth below or in the seawater around the detector, produce muons that can be observed by the Cherenkov radiation, which they emit. At an operating depth of 4000 metres, the detector is effectively shielded from muons produced in atmospheric interactions. {\\bf The site:} A major feature of the Ionian Sea floor is the Hellenic Trench, the deepest in the Mediterranean, which in places exceeds 5000 meters. It runs close to the western coast of the Peleponnese and is protected on its western side by the submarine Eastern Mediterranean Ridge. It is far from big city pollution or the effluent of major river systems flowing into the Mediterranean and is protected from deep-water perturbations.\\\\ The NESTOR site is located on a broad plateau some 8 $\\times$ 9 kilometres in area on the eastern side of the Hellenic Trench at a mean depth of...

  7. Noise Pollution

    Science.gov (United States)

    ... primarily to one’s overall health. Top of Page Health Effects Noise pollution adversely affects the lives of millions of people. ... its effect, disseminate information to the public regarding noise pollution and its adverse health effects, respond to inquiries on matters related to noise, ...

  8. Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine Program: Background and Issues for Congress

    Science.gov (United States)

    2015-12-17

    propulsion technology first occurred many years ago: To help jumpstart the UK’s nuclear - powered submarine program, the United States transferred to the UK a... nuclear - powered attack submarines (SSNs), nuclear - powered cruise missile submarines (SSGNs), and nuclear - powered ballistic missile submarines (SSBNs). 2...2 In the designations SSN, SSGN, SSBN, and SSBN(X), the SS stands for submarine, N stands for nuclear - powered (meaning the ship is

  9. Submarine landside in the Bussol Graben: Structural and formation features

    Science.gov (United States)

    Baranov, B. V.; Lobkovsky, L. I.; Dozorova, K. A.; Rukavishnikova, D. D.

    2017-05-01

    Analysis of geophysical data obtained during a study of the insular slope in the central Kuril‒Kamchatka Trench during projects Kuriles-2005 and Kuriles-2006 promoted by the Presidium of the Russian Academy of Sciences revealed a large submarine landslide in this area. The landslide, located at the bottom of the transverse valley confined to the Bussol l Graben, resulted from the failure of the northeastern wall of a graben composed of sedimentary material. It exceeds 35 km3 in size, representing one of the large submarine landslides discovered to date on the slope of the Kuril‒Kamchatka Trench in submarine canyonfan environments.

  10. Management of demand based inventory aboard submarine tenders servicing attack (SSN) submarines

    OpenAIRE

    Ross, Timothy Joseph

    1990-01-01

    Approved for public release; distribution is unlimited. This thesis examines the computation of inventory levels based on demand history aboard Submarine Tenders that use the Shipboard Automated Data Processing System (SUADPS) for inventory control. The focus of the thesis was the workload and supply effectiveness issues associated with the processing of the SUADPS levels setting program. The objective of the thesis was to determine the effect on supply effectiveness and stock churn if the...

  11. Seismic site response of submarine slope offshore southwestern Taiwan

    Directory of Open Access Journals (Sweden)

    Jing-Yi Lin

    2018-01-01

    Full Text Available Widely distributed Bottom-Simulating Reflectors (BSRs have been observed in the area offshore of southwestern Taiwan where the active accretionary complex meets with the passive China continental margin. In order to clarify the link between seismic site response and sedimentary properties of submarine slope, we evaluate the response of seafloor sediments in regard to passive dynamic loads. The local site effect produced by shallow marine sediments was characterized by estimating the horizontal-to-vertical (H/V spectral ratios of data recorded by the short-period Ocean Bottom Seismometers (OBSs. The results show that the maximal H/V ratios appeared in the range of 3.66 - 9.28 Hz, suggesting that the fundamental frequency is dominated by the effect related to the very shallow sediments. For most stations, the H/V ratios estimated based on the earthquakes and noise records were characterized by different patterns. Relatively broad H/V pattern was obtained when the signals were extracted from earthquakes. This phenomenon may be related to soil nonlinearity when a stronger motion applies. In comparison with the available geological structures and bulk density distribution obtained from coring experiments, we found a relatively higher fundamental frequency of about 8 - 9 Hz for the more rigid material, such as mud diapir and folding axes. For most of the area along the slope, the fundamental frequency shows a relatively low value, about 6 - 8 Hz. Finally, when a site is characterized by thick or lowest bulk density sedimentary layer, we observed a fundamental frequency lower than 5 Hz, which is the lowest in our assessment.

  12. Submarine thermal springs on the Galapagos Rift

    Science.gov (United States)

    Corliss, J.B.; Dymond, J.; Gordon, L.I.; Edmond, J.M.; Von Herzen, R. P.; Ballard, Richard D.; Green, K.; Williams, D.; Bainbridge, A.; Crane, K.; Van Andel, T. H.

    1979-01-01

    The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis

  13. Improved OTEC System for a Submarine Robot

    Science.gov (United States)

    Chao, Yi; Jones, Jack; Valdez, Thomas

    2010-01-01

    An ocean thermal energy conversion (OTEC), now undergoing development, is a less-massive, more-efficient means of exploiting the same basic principle as that of the proposed system described in "Alternative OTEC Scheme for a Submarine Robot" (NPO-43500), NASA Tech Briefs, Vol. 33, No. 1 (January 2009), page 50. The proposed system as described previously would be based on the thawing-expansion/freezing-contraction behavior of a wax or perhaps another suitable phase-change material (PCM). The power generated by the system would be used to recharge the batteries in a battery- powered unmanned underwater vehicle [UUV (essentially, a small exploratory submarine robot)] of a type that has been deployed in large numbers in research pertaining to global warming. A UUV of this type travels between the ocean surface and depths, measuring temperature and salinity. At one phase of its operational cycle, the previously proposed system would utilize the surface ocean temperature (which lies between 15 and 30 C over most of the Earth) to melt a PCM that has a melting/freezing temperature of about 10 C. At the opposite phase of its operational cycle, the system would utilize the lower ocean temperature at depth (e.g., between 4 and 7 C at a depth of 300 m) to freeze the PCM. The melting or freezing would cause the PCM to expand or contract, respectively, by about 9 volume percent. The PCM would be contained in tubes that would be capable of expanding and contracting with the PCM. The PCM-containing tubes would be immersed in a hydraulic fluid. The expansion and contraction would drive a flow of the hydraulic fluid against a piston that, in turn, would push a rack-and-pinion gear system to spin a generator to charge a battery.

  14. A model for tidewater glacier undercutting by submarine melting

    Science.gov (United States)

    Slater, D. A.; Nienow, P. W.; Goldberg, D. N.; Cowton, T. R.; Sole, A. J.

    2017-03-01

    Dynamic change at the marine-terminating margins of the Greenland Ice Sheet may be initiated by the ocean, particularly where subglacial runoff drives vigorous ice-marginal plumes and rapid submarine melting. Here we model submarine melt-driven undercutting of tidewater glacier termini, simulating a process which is key to understanding ice-ocean coupling. Where runoff emerges from broad subglacial channels we find that undercutting has only a weak impact on local submarine melt rate but increases total ablation by submarine melting due to the larger submerged ice surface area. Thus, the impact of melting is determined not only by the melt rate magnitude but also by the slope of the ice-ocean interface. We suggest that the most severe undercutting occurs at the maximum height in the fjord reached by the plume, likely promoting calving of ice above. It remains unclear, however, whether undercutting proceeds sufficiently rapidly to influence calving at Greenland's fastest-flowing glaciers.

  15. Submarine Upward Looking Sonar Ice Draft Profile Data and Statistics

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of upward looking sonar draft data collected by submarines in the Arctic Ocean. It includes data from both U.S. Navy and Royal Navy...

  16. Virtual Reality Training System for a Submarine Command Center

    National Research Council Canada - National Science Library

    Maxwell, Douglas B

    2008-01-01

    The invention as disclosed is a system that uses a combined real and virtual display interaction methodology to generate the visual appearance of submarine combat control rooms and allow interaction...

  17. Sun glitter imaging analysis of submarine sand waves in HJ-1A/B satellite CCD images

    Science.gov (United States)

    Zhang, Huaguo; He, Xiekai; Yang, Kang; Fu, Bin; Guan, Weibing

    2014-11-01

    Submarine sand waves are a widespread bed-form in tidal environment. Submarine sand waves induce current convergence and divergence that affect sea surface roughness thus become visible in sun glitter images. These sun glitter images have been employed for mapping sand wave topography. However, there are lots of effect factors in sun glitter imaging of the submarine sand waves, such as the imaging geometry and dynamic environment condition. In this paper, several sun glitter images from HJ-1A/B in the Taiwan Banks are selected. These satellite sun glitter images are used to discuss sun glitter imaging characteristics in different sensor parameters and dynamic environment condition. To interpret the imaging characteristics, calculating the sun glitter radiance and analyzing its spatial characteristics of the sand wave in different images is the best way. In this study, a simulated model based on sun glitter radiation transmission is adopted to certify the imaging analysis in further. Some results are drawn based on the study. Firstly, the sun glitter radiation is mainly determined by sensor view angle. Second, the current is another key factor for the sun glitter. The opposite current direction will cause exchanging of bright stripes and dark stripes. Third, brightness reversal would happen at the critical angle. Therefore, when using sun glitter image to obtain depth inversion, one is advised to take advantage of image properties of sand waves and to pay attention to key dynamic environment condition and brightness reversal.

  18. Studies on submarine control for periscope depth operations

    OpenAIRE

    Tolliver, John V.

    1996-01-01

    Approved for public release; distribution in unlimited. Requirements for submarine periscope depth operations have been increased by integration with carrier battle groups, littoral operations, and contributions to joint surveillance. Improved periscope depth performance is therefore imperative. Submarine control personnel rely on a large number of analog gauges and indications. An integrated digital display system could enhance the ergonomics of the human control interface and display add...

  19. Exercise Aboard Attack Submarines: Rationale and New Options

    Science.gov (United States)

    2004-08-18

    experience loss of physical fitness while underway. Bennett and co-workers (2) noted a 7% reduction of maximal oxygen consumption in non-exercising...Inc. designed and built a comprehensive resistance exercise device to help counteract muscle deconditioning during long term space flights (the SX... Physical activity aboard nuclear submarines as measured by pedometry. Groton: Naval Submarine Medical Research Laboratory, Report 1053, 1985, p. 12

  20. Are tilt measurements useful in detecting tsunamigenic submarine landslides?

    OpenAIRE

    Sascha Brune; Andrey Babeyko; Stephan V. Sobolev

    2009-01-01

    Large submarine landslides can generate dangerous tsunamis. Because of their long-period signal, detection of landslides by common seismological methods is difficult. Here we suggest a method of detecting submarine landslides by using an array of land-based tiltmeters. The displacement of a large volume of sediments during landsliding produces a detectable elastic response of the lithosphere. We propose a technique to calculate this response and to invert for tsunami relevant parameters like ...

  1. Active noise control using noise source having adaptive resonant frequency tuning through stress variation

    Science.gov (United States)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by an expandable ring embedded in the noise radiating element. Excitation of the ring causes expansion or contraction of the ring, thereby varying the stress in the noise radiating element. The ring is actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the ring, causing the ring to expand or contract. Instead of a single ring embedded in the noise radiating panel, a first expandable ring can be bonded to one side of the noise radiating element, and a second expandable ring can be bonded to the other side.

  2. The development of permafrost bacterial communities under submarine conditions

    Science.gov (United States)

    Mitzscherling, Julia; Winkel, Matthias; Winterfeld, Maria; Horn, Fabian; Yang, Sizhong; Grigoriev, Mikhail N.; Wagner, Dirk; Overduin, Pier P.; Liebner, Susanne

    2017-07-01

    Submarine permafrost is more vulnerable to thawing than permafrost on land. Besides increased heat transfer from the ocean water, the penetration of salt lowers the freezing temperature and accelerates permafrost degradation. Microbial communities in thawing permafrost are expected to be stimulated by warming, but how they develop under submarine conditions is completely unknown. We used the unique records of two submarine permafrost cores from the Laptev Sea on the East Siberian Arctic Shelf, inundated about 540 and 2500 years ago, to trace how bacterial communities develop depending on duration of the marine influence and pore water chemistry. Combined with geochemical analysis, we quantified total cell numbers and bacterial gene copies and determined the community structure of bacteria using deep sequencing of the bacterial 16S rRNA gene. We show that submarine permafrost is an extreme habitat for microbial life deep below the seafloor with changing thermal and chemical conditions. Pore water chemistry revealed different pore water units reflecting the degree of marine influence and stages of permafrost thaw. Millennia after inundation by seawater, bacteria stratify into communities in permafrost, marine-affected permafrost, and seabed sediments. In contrast to pore water chemistry, the development of bacterial community structure, diversity, and abundance in submarine permafrost appears site specific, showing that both sedimentation and permafrost thaw histories strongly affect bacteria. Finally, highest microbial abundance was observed in the ice-bonded seawater unaffected but warmed permafrost of the longer inundated core, suggesting that permafrost bacterial communities exposed to submarine conditions start to proliferate millennia after warming.

  3. Cardiometabolic Health in Submariners Returning from a 3-Month Patrol

    Directory of Open Access Journals (Sweden)

    Heath G. Gasier

    2016-02-01

    Full Text Available Confined space, limited exercise equipment, rotating shift work and reduced sleep may affect cardiometabolic health in submariners. To test this hypothesis, 53 male U.S. Submariners (20–39 years were studied before and after a 3-month routine submarine patrol. Measures included anthropometrics, dietary and physical activity, biomarkers of cardiometabolic health, energy and appetite regulation, and inflammation. Before deployment, 62% of submariners had a body fat % (BF% ≥ 25% (obesity, and of this group, 30% met the criteria for metabolic syndrome. In obese volunteers, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR, leptin, the leptin/adiponectin ratio, and pro-inflammatory chemokines growth-related oncogene and macrophage-derived chemokine were significantly higher compared to non-obese submariners. Following the patrol, a significant mean reduction in body mass (5% and fat-mass (11% occurred in the obese group as a result of reduced energy intake (~2000 kJ during the patrol; and, independent of group, modest improvements in serum lipids and a mean reduction in interferon γ-induced protein 10 and monocyte chemotactic protein 1 were observed. Since 43% of the submariners remained obese, and 18% continued to meet the criteria for metabolic syndrome following the patrol, the magnitude of weight loss was insufficient to completely abolish metabolic dysfunction. Submergence up to 3-months, however, does not appear to be the cause of obesity, which is similar to that of the general population.

  4. Solution of Supplee's submarine paradox through special and general relativity

    CERN Document Server

    Vieira, R S

    2016-01-01

    In 1989 Supplee described an apparent relativistic paradox on which a submarine seems to sink in a given frame while floating in another one. If the submarine density is adjusted to be the same as the water density (when both of them are at rest) and then it is put to move, the density of the submarine will become higher than that of the water, thanks to Lorentz contraction, and hence it sinks. However, in the submarine proper frame, is the water that becomes denser, so the submarine supposedly should float and we get a paradox situation. In this paper we analyze the submarine paradox in both a flat and a curved spacetime. In the case of a flat spacetime, we first show that any relativistic force field in special relativity can be written in the Lorentz form, so that it can always be decomposed into a static (electric-like) and a dynamic (magnetic-like) part. Taking into account the gravitomagnetic effects between the Earth and the water, a relativistic formulation of Archimedes principle can be established, ...

  5. Noise Protection

    Science.gov (United States)

    1980-01-01

    Environmental Health Systems puts forth an increasing effort in the U.S. to develop ways of controlling noise, particularly in industrial environments due to Federal and State laws, labor union insistence and new findings relative to noise pollution impact on human health. NASA's Apollo guidance control system aided in the development of a noise protection product, SMART. The basis of all SMART products is SMART compound a liquid plastic mixture with exceptional energy/sound absorbing qualities. The basic compound was later refined for noise protection use.

  6. Submarine Landslides at Santa Catalina Island, California

    Science.gov (United States)

    Legg, M. R.; Francis, R. D.

    2011-12-01

    Santa Catalina Island is an active tectonic block of volcanic and metamorphic rocks originally exposed during middle Miocene transtension along the evolving Pacific-North America transform plate boundary. Post-Miocene transpression created the existing large pop-up structure along the major strike-slip restraining bend of the Catalina fault that forms the southwest flank of the uplift. Prominent submerged marine terraces apparent in high-resolution bathymetric maps interrupt the steep submarine slopes in the upper ~400 meters subsea depths. Steep subaerial slopes of the island are covered by Quaternary landslides, especially at the sea cliffs and in the blueschist metamorphic rocks. The submarine slopes also show numerous landslides that range in area from a few hectares to more than three sq-km (300 hectares). Three or more landslides of recent origin exist between the nearshore and first submerged terrace along the north-facing shelf of the island's West End. One of these slides occurred during September 2005 when divers observed a remarkable change in the seafloor configuration after previous dives in the area. Near a sunken yacht at about 45-ft depth where the bottom had sloped gently into deeper water, a "sinkhole" had formed that dropped steeply to 100-ft or greater depths. Some bubbling sand was observed in the shallow water areas that may be related to the landslide process. High-resolution multibeam bathymetry acquired in 2008 by CSU Monterey Bay show this "fresh" slide and at least two other slides of varying age along the West End. The slides are each roughly 2 hectares in area and their debris aprons are spread across the first terrace at about 85-m water depth that is likely associated with the Last Glacial Maximum sealevel lowstand. Larger submarine slides exist along the steep Catalina and Catalina Ridge escarpments along the southwest flank of the island platform. A prominent slide block, exceeding 3 sq-km in area, appears to have slipped more than

  7. ROV Tiburon Investigation of Hawaiian Submarine Canyons

    Science.gov (United States)

    Paull, C. K.; Greene, H. G.; Caress, D. W.; Clague, D. A.; Ussler, W.; Maher, N. M.

    2001-12-01

    MBARI conducted ROV dives around the Hawaiian Islands during an expedition of the R/V Western Flyer and Tiburon in the spring of 2001. Eight ROV dives were made to investigate five major submarine canyons offshore of Oahu, Molokai, and Hawaii in up to 3,434 m water depths. Four of these canyons are located off the windward (northern) side of these islands where onshore canyons are also well developed. Those canyons located offshore of Molokai and Oahu incise the head scars of the giant Nuuanu and Wailai submarine landslides. ROV observations and sediment and rock outcrop sampling were made in these canyons to determine their origin and present-day activity. The fifth canyon investigated is located on the leeward (southern) side of Molokai. The canyons along the windward side expose extensive stratigraphic sections that reveal the history of the islands' formation. In composite, these sections contain marine pillow basalt overlain by a substantial sequence of alternating subaerial lava flows, rounded boulder conglomerates, shallow water carbonates, and hyaloclastites that indicate coastal and marine deposition. These sequences illustrate the accretion and subsequent subsidence of the islands' flanks. These canyons also have morphologically distinct upper and lower sections. The upper reaches of the canyons are incised into the shallow water marine facies and contain broad axial channels through which active sediment transport is occurring. In contrast, the morphology of the lower canyons are strongly influenced by the giant landslides that massively altered the northern flanks of the Hawaiian chain. The lower canyons contain plunge pools and steep headwall scarps that are generally comprised of mechanically competent subaerial lava flows. The presence of multiple plunge pools with differentially eroded head scarps suggests retrogressive erosion (bottom-up process) with headward advancement of the various heads. Undercutting of the headwalls also produce periodic

  8. From submarine to lacustrine groundwater discharge

    Science.gov (United States)

    Lewandowski, Jörg; Meinikmann, Karin; Pöschke, Franziska; Nützmann, Gunnar; Rosenberry, Donald O.

    2017-01-01

    Submarine groundwater discharge (SGD) and its role in marine nutrient cycling are well known since the last decade. The freshwater equivalent, lacustrine groundwater discharge (LGD), is often still disregarded, although first reports of LGD are more than 50 years old. We identify nine different reasons why groundwater has long been disregarded in both freshwater and marine environments such as invisibility of groundwater discharge, the size of the interface and its difficult accessibility. Although there are some fundamental differences in the hydrology of SGD and LGD, caused primarily by seawater recirculation that occurs only in cases of SGD, there are also a lot of similarities such as a focusing of discharge to near-shore areas. Nutrient concentrations in groundwater near the groundwater–surface water interface might be anthropogenically enriched. Due to spatial heterogeneity of aquifer characteristics and biogeochemical processes, the quantification of groundwater-borne nutrient loads is challenging. Both nitrogen and phosphorus might be mobile in near-shore aquifers and in a lot of case studies large groundwater-borne nutrient loads have been reported.

  9. Design and analysis of submarine radome

    Science.gov (United States)

    Sandeep, C. Satya; Prasad, U. Shiva; Suresh, R.; Rathan, A.; Sravanthi, G.; Govardhan, D.

    2017-07-01

    Radomes are the electromagnetic windows that protect microwave sub-systems from the environmental effects. The major requirement of radome is its transparency to microwaves and for most of the cases mechanical properties are also equally important. Radome for underwater applications has to withstand high water pressure of the order of 45 bars. Composite materials owing to their high strength to weight ratio, high stiffness and better corrosion resistance are potential source for under water applications. The concept of 'tailoring' the material properties to suit the radome is obtained by selecting proper reinforcement, resin matrix and their compositions. The mechanical properties of composite material, evaluated by testing specimens as per ASTM standards, are utilized in designing the radome. The modulus properties calculated using classical theories of composite materials and compared with test results. ANSYS a Finite Element software package used to analyse the problem. As the cross sectional thickness of radome varies, the complexity in fabrication is overcome by adopting matched die techniques. The radome design and finite element analysis validation concluded by conducting the pressure test on radome. On the design a modal analysis is also carried to check for the natural frequency, So that resonance does not occur if the natural frequency of the radome coincides with the excitation frequency of the submarine Clinical information system (CIS) for UNRWA is a computerized distributed application that used in clinics which follows the United Nations Relief and Works Agency (UNRWA) to manage the clinical requirements and services.

  10. Submarine landslides of the Southern California Borderland

    Science.gov (United States)

    Lee, H.J.; Greene, H. Gary; Edwards, B.D.; Fisher, M.A.; Normark, W.R.

    2009-01-01

    Conventional bathymetry, sidescan-sonar and seismic-reflection data, and recent, multibeam surveys of large parts of the Southern California Borderland disclose the presence of numerous submarine landslides. Most of these features are fairly small, with lateral dimensions less than ??2 km. In areas where multibeam surveys are available, only two large landslide complexes were identified on the mainland slope- Goleta slide in Santa Barbara Channel and Palos Verdes debris avalanche on the San Pedro Escarpment south of Palos Verdes Peninsula. Both of these complexes indicate repeated recurrences of catastrophic slope failure. Recurrence intervals are not well constrained but appear to be in the range of 7500 years for the Goleta slide. The most recent major activity of the Palos Verdes debris avalanche occurred roughly 7500 years ago. A small failure deposit in Santa Barbara Channel, the Gaviota mudflow, was perhaps caused by an 1812 earthquake. Most landslides in this region are probably triggered by earthquakes, although the larger failures were likely conditioned by other factors, such as oversteepening, development of shelf-edge deltas, and high fluid pressures. If a subsequent future landslide were to occur in the area of these large landslide complexes, a tsunami would probably result. Runup distances of 10 m over a 30-km-long stretch of the Santa Barbara coastline are predicted for a recurrence of the Goleta slide, and a runup of 3 m over a comparable stretch of the Los Angeles coastline is modeled for the Palos Verdes debris avalanche. ?? 2009 The Geological Society of America.

  11. Seismic reflections associated with submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Andreassen, K.

    1995-12-31

    Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

  12. Submarine landslides in Arctic sedimentation: Canada Basin

    Science.gov (United States)

    Mosher, David C.; Shimeld, John; Hutchinson, Deborah R.; Lebedova-Ivanova, N; Chapman, C.

    2016-01-01

    Canada Basin of the Arctic Ocean is the least studied ocean basin in the World. Marine seismic field programs were conducted over the past 6 years using Canadian and American icebreakers. These expeditions acquired more than 14,000 line-km of multibeam bathymetric and multi-channel seismic reflection data over abyssal plain, continental rise and slope regions of Canada Basin; areas where little or no seismic reflection data existed previously. Canada Basin is a turbidite-filled basin with flat-lying reflections correlateable over 100s of km. For the upper half of the sedimentary succession, evidence of sedimentary processes other than turbidity current deposition is rare. The Canadian Archipelago and Beaufort Sea margins host stacked mass transport deposits from which many of these turbidites appear to derive. The stratigraphic succession of the MacKenzie River fan is dominated by mass transport deposits; one such complex is in excess of 132,000 km2 in area and underlies much of the southern abyssal plain. The modern seafloor is also scarred with escarpments and mass failure deposits; evidence that submarine landsliding is an ongoing process. In its latest phase of development, Canada Basin is geomorphologically confined with stable oceanographic structure, resulting in restricted depositional/reworking processes. The sedimentary record, therefore, underscores the significance of mass-transport processes in providing sediments to oceanic abyssal plains as few other basins are able to do.

  13. Impact of image noise levels, scout scan dose and lens shield on image quality and radiation exposure in z-axis dose-modulated neck MSCT on 16- and 64-slice Toshiba Aquilion scanners.

    Science.gov (United States)

    Bauknecht, Hans-Christian; Jach, Cornelia; Bohner, Georg; Meyer, Henning; Scheurig, Christian; Siebert, Eberhard; Klingebiel, Randolf

    2010-02-01

    Assessing the impact of image noise (IN) levels, scout scan dose and lens shield use on image quality and radiation exposure in neck multislice CT (MSCT) when using z-axis dose modulation (DM). Neck MSCT phantom studies with/without z-axis DM were performed by using different IN levels (S.D. 7.5-30HU) and scout scan tube currents (7.5-50mA) on Toshiba Aquilion scanners (16-/64-slice). Image quality indices were evaluated by two radiologists and radiation exposure parameters calculated. Cadaveric phantom measurements elucidated lens shield interactions with DM efficacy. The lowest dose scan protocol with diagnostic image quality was introduced into the clinical imaging routine and retrospectively evaluated in 20 age-matched patients undergoing neck MSCT with/without DM. The highest image noise level in DM neck studies with comparable image quality to standard neck CT amounted to 20HU, resulting in a mean tube current of 50mAs (CTDI(w) 6.3mGy). DM reduced effective dose by 35% and organ dose figures (lens, thyroid) by 33%. Scout scan dose lowering to 20mA resulted in an effective dose (ED) decrease of 0.06mSv (5%). Avoiding lens shield placement during scout scan effected an organ dose decrease of 20%. Overall contour sharpness and image contrast did not differ significantly (DM/without DM) whereas image noise was rated higher in DM neck CT studies (pToshiba Aquilion scanners, is effective and mandatory in neck MSCT. DM efficacy can be enhanced by optimising scout scan doses and lens shield use. Copyright (c) 2008 Elsevier Ireland Ltd. All rights reserved.

  14. Technique for estimating the sound power level radiated by pneumatic rock drills and the evaluation of a CSIR prototype rock drill with engineering noise controls

    CSIR Research Space (South Africa)

    Kovalchik, PG

    2009-05-01

    Full Text Available This report describes the procedure for the measurement and reporting of noise from portable pneumatic tools such as jackleg drills. The technique used in this research allows for the determination of the source A-weighted sound power levels...

  15. NSMRL: A Small Command with A Huge Presence for the Submarine Force

    National Research Council Canada - National Science Library

    Daniel, J. C; Lamb, Jerry

    2005-01-01

    "To protect the health and enhance the performance of our warfighters through focused submarine, diving and surface research solutions" is the mission of the Naval Submarine Medical Research Laboratory (NSMRL...

  16. Conduct and Support of Amphibious Operations from United States Submarines in World War II

    Science.gov (United States)

    2010-11-01

    twelfth war patrol of the Gato class submarine (See photos 1 and 2). They made history as the only Americans to conduct an offensive landing on a...Naval History Vol. 2, no. 1 (April 1, 2003), 1. 4 This monograph features five Gato class submarines, and three V-class submarines, but also addresses...1993), 67. 6 Photo 2: USS Barb (SS 220), representing the five Gato class submarines that participated in Operation Torch. Barb’s crew also

  17. Index of Submarine Medical Officer’s Qualification Theses 1944-1974

    Science.gov (United States)

    1976-04-01

    DEAD SPACE MEASUREMENTS BEFCRE AND 1968-3009 -- ESP IRATORY DEAD SPACE VARIAION TUDINVL---t b-0 9 INJURIES ON+ A SYLLABUS DEALING WITH THE MANAGEMENT OF...SUBARIkNE MEDICINEO A SYLLABUS OF.- SUBMARINE MEDICAL QUALIFICATION THESES U. S. NAVAL SJBMARINE MEDICAL CENTER SUBMARIN BASE, NEW LCNOOjN, GROTON...CARBON DIOXIDE ABSORBENT EVALUATION AND CANNISTER DESIGN *= SUBMARINE MDCLUALIFICATICN THESES U. -S.NAVAL SUBMARE MEDICAL CENTER SUBMARINE BASE, NEW LCNDON

  18. Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine Program: Background and Issues for Congress

    Science.gov (United States)

    2016-04-05

    Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine Program: Background and Issues for Congress Ronald O’Rourke Specialist in Naval...Affairs April 5, 2016 Congressional Research Service 7-5700 www.crs.gov R41129 Navy Ohio Replacement (SSBN[X]) Ballistic Missile Submarine...Replacement (SSBN[X]) Ballistic Missile Submarine Program Congressional Research Service Contents Introduction

  19. Submarine fans: A critical retrospective (1950–2015

    Directory of Open Access Journals (Sweden)

    G. Shanmugam

    2016-04-01

    Full Text Available When we look back the contributions on submarine fans during the past 65 years (1950–2015, the empirical data on 21 modern submarine fans and 10 ancient deep-water systems, published by the results of the First COMFAN (Committee on FANs Meeting (Bouma et al., 1985a, have remained the single most significant compilation of data on submarine fans. The 1970s were the “heyday” of submarine fan models. In the 21st century, the general focus has shifted from submarine fans to submarine mass movements, internal waves and tides, and contourites. The purpose of this review is to illustrate the complexity of issues surrounding the origin and classification of submarine fans. The principal elements of submarine fans, composed of canyons, channels, and lobes, are discussed using nine modern case studies from the Mediterranean Sea, the Equatorial Atlantic, the Gulf of Mexico, the North Pacific, the NE Indian Ocean (Bay of Bengal, and the East Sea (Korea. The Annot Sandstone (Eocene–Oligocene, exposed at Peira-Cava area, SE France, which served as the type locality for the “Bouma Sequence”, was reexamined. The field details are documented in questioning the validity of the model, which was the basis for the turbidite-fan link. The 29 fan-related models that are of conceptual significance, developed during the period 1970–2015, are discussed using modern and ancient systems. They are: (1 the classic submarine fan model with attached lobes, (2 the detached-lobe model, (3 the channel-levee complex without lobes, (4 the delta-fed ramp model, (5 the gully-lobe model, (6 the suprafan lobe model, (7 the depositional lobe model, (8 the fan lobe model, (9 the ponded lobe model, (10 the nine models based on grain size and sediment source, (11 the four fan models based on tectonic settings, (12 the Jackfork debrite model, (13 the basin-floor fan model, (14 supercritical and subcritical fans, and (15 the three types of fan reservoirs. Each model is unique

  20. Process sedimentology of submarine fan deposits - new perspectives

    Science.gov (United States)

    Postma, George

    2017-04-01

    To link submarine fan process sedimentology with sand distribution, sand body architecture, texture and fabric, the field geologist studies sedimentary facies, facies associations (fan elements) and stratigraphy. Facies analysis resides on factual knowledge of modern fan morphodynamics and physical modelling of en-masse sediment transport. Where do we stand after 55 years of submarine research, i.e. the date when the first submarine fan model was launched by Arnold Bouma in 1962? Since that date students of submarine fans have worked on a number of important, recurring questions concerned with facies analysis of submarine successions in outcrop and core: 1. What type of sediment transport produced the beds? 2. What facies can be related to initial flow conditions? 3. What is the significance of grain size jumps and bounding surface hierarchy in beds consisting of crude and spaced stratification (traction carpets)? Do these point to multi flow events or to flow pulsations by one and the same event? 4. What facies associations relate to the basic elements of submarine fans? 5. What are the autogenic and allogenic signatures in submarine fans? Particularly in the last decade, the enormous technical advancement helped to obtain high-quality data from observations of density flows in modern canyons, deep basins and deep-water delta slopes (refs 1,2,3). In combination with both physical (refs 4,5) and numerical modelling (ref 6) these studies broke new ground into our understanding of density flow processes in various submarine environments and have led to new concepts of submarine fan building by super- and subcritical high-density flow (ref 7). Do these new concepts provide better answers to our recurrent questions related to the morphodynamics of submarine fans and prediction of sand body architecture? In discussing this open question, I shall 1. apply the new concepts to a modern and ancient example of a channel-lobe-transition-zone (ref 8); 2. raise the problem of

  1. Drone noise

    Science.gov (United States)

    Tinney, Charles; Sirohi, Jayant; University of Texas at Austin Team

    2017-11-01

    A basic understanding of the noise produced by single and multirotor drones operating at static thrust conditions is presented. This work acts as an extension to previous efforts conducted at The University of Texas at Austin (Tinney et al. 2017, AHS Forum 73). Propeller diameters ranging from 8 inch to 12 inch are examined for configurations comprising an isolated rotor, a quadcopter configuration and a hexacopter configuration, and with a constant drone pitch of 2.25. An azimuthal array of half-inch microphones, placed between 2 and 3 hub-center diameters from the drone center, are used to assess the acoustic near-field. Thrust levels, acquired using a six degree-of-freedom load cell, are then used to correlate acoustic noise levels to aerodynamic performance for each drone configuration. The findings reveal a nearly logarithmic increase in noise with increasing thrust. However, for the same thrust condition, considerable noise reduction is achieved by increasing the number of propeller blades thereby reducing the blade passage frequency and both the thickness and loading noise sources that accompany it.

  2. The May 2010 submarine eruption from South Sarigan seamount, Northern Mariana Islands

    Science.gov (United States)

    McGimsey, R. G.; Neal, C. A.; Searcy, C. K.; Camacho, J. T.; Aydlett, W. B.; Embley, R. W.; Trusdell, F.; Paskievitch, J. F.; Schneider, D. J.

    2010-12-01

    at the time of the explosion reported hearing a loud noise from the south, and shortly thereafter receiving a dusting of ash. They also reported the sound of a water wave passing by; a tide gauge in Saipan recorded a wave on the order of 4-5 cm. The eruption was followed by a rapid return to relative quiescence with occasional earthquakes (0-3 per day) recorded throughout the summer. The eruption appears to have originated from South Sarigan seamount, about 12 km south of Sarigan Island. The summit of the seamount is poorly surveyed but appears to consist of several peaks with minimum depths ranging up to ~184 m BSL including a small (young?) cone at ~350 m BSL. Sidescan sonar data collected in 2003 show that the flank of the seamount is characterized by radiating patterns of high acoustic backscatter indicating recent mass flows of volcaniclastic material, which suggests that this is a frequently active volcano.

  3. Low Noise Amplifiers

    Science.gov (United States)

    Petty, S. M.; Trowbridge, D. L.

    1983-01-01

    One of the great technical challenges facing the Deep Space Network is receiving signals from a severely weight limited spacecraft hundreds of thousands to billions of kilometers from Earth. This weight limitation has always imposed strict limitations on the size of the spacecraft antenna and the amount of transmitter power radiated. The communication burden is placed upon the ground systems of the Deep Space Network which must recover an extremely weak signal in the presence of nearly overwhelming amounts of noise. Two key parameters that determine the signal to noise ratio of a received signal using a deep space station are the collecting area and efficiency of the antenna, and the amount of noise which is generated in, as well as allowed to enter in, the antenna-mounted receiver. These parameters are used to describe the relative ability of a deep space station to receive weak signals. As spacecraft to Earth communication distances have increased, the Deep Space Network engages in a relentless effort to increase the figure of merit through larger and more efficient antennas, higher frequencies, and lower system noise temperature.

  4. Results of radioactivity analysis made in Corsica following the navigation incident of the USS Hartford submarine; Resultats des analyses de radioactivite effectuees en Corse suite a l'incident de navigation du sous-marin USS Hartford

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-11-01

    No radiological impact has been revealed in relation with the navigation incident of the Uss Hartford submarine at the north of Sardinia. The analysis have been made by the Institute of radiation protection and nuclear safety (I.R.S.N.).The Uss Hartford submarine had hit the bottom of the sea, on the 25. of october 2003, between the islands of Sardinia at a thirty kilometers distance in the south of Bonifacio. The accident had been declared to the public only on the 12. of November 2003. (N.C.)

  5. First Use of an Autonomous Glider for Exploring Submarine Volcanism in the SW Pacific

    Science.gov (United States)

    Matsumoto, H.; Embley, R. W.; Haxel, J. H.; Dziak, R. P.; Bohnenstiehl, D. R.; Stalin, S.; Meinig, C.

    2010-12-01

    A 1000-m Slocum glider® (Teledyne Webb Research Corporation) with CTD, turbidity, and hydrophone sensors was operated for two days in the Northeast Lau Basin. The survey was conducted near West Mata Volcano, where in November of 2008 the NOAA PMEL Vents program observed an active eruption at its 1207 m summit—the deepest submarine activity ever before witnessed. Our goal was to use the glider as a forensic tool to search for other nearby eruption sites with onboard sensors that detect the chemical and hydroacoustic signatures associated with the volcanic and hydrothermal plumes. The glider was launched approximately 40 km to the west of West Mata. It flew toward West Mata and was recovered near the summit of the volcano after repeating 13 yos during a 41-hour mission. Although the recordings were affected by mechanical noise from the glider’s rudder, the data demonstrate that the system can detect the wide-band noises (>1 kHz) associated with submarine volcanic and intense hydrothermal activity. The glider recorded complex acoustic amplitudes due to the multiple raypaths from West Mata as well as temporal variations in the volcano’s rate of activity, and demonstrated that these geologic processes contribute to the region’s high ambient noise levels. With the exception of the deployment and recovery, the mission was managed entirely by the shore teams in PMEL (Seattle, WA) and OSU labs (Newport, OR), ~5000 miles away without an engineer onboard. The dive cycle of the 950-m dives was ~3.5 hours and the average speed was ~0.27 cm/s. The CTD data were downloaded at every surface cycle and appeared to be of high quality. However we found that the sensitivity of the Wetlabs ECO flntu turbidity sensor was not adequate for the detection of volcanic plumes. The mission demonstrated PMEL’s ability to use autonomous gliders to monitor a variety of environmental parameters including ambient sound levels, temperature, salinity and turbidity for the purpose of finding

  6. A submarine volcanic eruption leads to a novel microbial habitat.

    Science.gov (United States)

    Danovaro, Roberto; Canals, Miquel; Tangherlini, Michael; Dell'Anno, Antonio; Gambi, Cristina; Lastras, Galderic; Amblas, David; Sanchez-Vidal, Anna; Frigola, Jaime; Calafat, Antoni M; Pedrosa-Pàmies, Rut; Rivera, Jesus; Rayo, Xavier; Corinaldesi, Cinzia

    2017-04-24

    Submarine volcanic eruptions are major catastrophic events that allow investigation of the colonization mechanisms of newly formed seabed. We explored the seafloor after the eruption of the Tagoro submarine volcano off El Hierro Island, Canary Archipelago. Near the summit of the volcanic cone, at about 130 m depth, we found massive mats of long, white filaments that we named Venus's hair. Microscopic and molecular analyses revealed that these filaments are made of bacterial trichomes enveloped within a sheath and colonized by epibiotic bacteria. Metagenomic analyses of the filaments identified a new genus and species of the order Thiotrichales, Thiolava veneris. Venus's hair shows an unprecedented array of metabolic pathways, spanning from the exploitation of organic and inorganic carbon released by volcanic degassing to the uptake of sulfur and nitrogen compounds. This unique metabolic plasticity provides key competitive advantages for the colonization of the new habitat created by the submarine eruption. A specialized and highly diverse food web thrives on the complex three-dimensional habitat formed by these microorganisms, providing evidence that Venus's hair can drive the restart of biological systems after submarine volcanic eruptions.

  7. Does calving matter? Evidence for significant submarine melt

    Science.gov (United States)

    Bartholomaus, Timothy C.; Larsen, Christopher F.; O’Neel, Shad

    2013-01-01

    During the summer in the northeast Pacific Ocean, the Alaska Coastal Current sweeps water with temperatures in excess of 12 °C past the mouths of glacierized fjords and bays. The extent to which these warm waters affect the mass balance of Alaskan tidewater glaciers is uncertain. Here we report hydrographic measurements made within Icy Bay, Alaska, and calculate rates of submarine melt at Yahtse Glacier, a tidewater glacier terminating in Icy Bay. We find strongly stratified water properties consistent with estuarine circulation and evidence that warm Gulf of Alaska water reaches the head of 40 km-long Icy Bay, largely unaltered. A 10–20 m layer of cold, fresh, glacially-modified water overlies warm, saline water. The saline water is observed to reach up to 10.4 °C within 1.5 km of the terminus of Yahtse Glacier. By quantifying the heat and salt deficit within the glacially-modified water, we place bounds on the rate of submarine melt. The submarine melt rate is estimated at >9 m d−1, at least half the rate at which ice flows into the terminus region, and can plausibly account for all of the submarine terminus mass loss. Our measurements suggest that summer and fall subaerial calving is a direct response to thermal undercutting of the terminus, further demonstrating the critical role of the ocean in modulating tidewater glacier dynamics.

  8. Submarine Construction in Germany (U-Bootbau in Deutschland),

    Science.gov (United States)

    1983-04-25

    the IKL sister firm, Maschinenbau Gabler GmbH, also founded by Prof. Gabler, which, unlike IKL (involved solely in development), is a hardware...snorkels, radar masts, as well as wharf and dockside connections, for IKL and various submarine yards. Moreover, Maschinenbau Gabler is engaged in

  9. Dissolved Nutrients from Submarine Groundwater in Flic en Flac ...

    African Journals Online (AJOL)

    Abstract—The aim of this study was to investigate dissolved nutrients in a submarine groundwater discharge (SGD) in Flic en Flac lagoon on the west coast of the volcanic island of Mauritius. The SGD enters Flic en Flac lagoon through a thin blanket of unconsolidated sediment through a fracture system and is concentrated ...

  10. Dissolved Nutrients from Submarine Groundwater in Flic en Flac ...

    African Journals Online (AJOL)

    The aim of this study was to investigate dissolved nutrients in a submarine groundwater discharge (SGD) in Flic en Flac lagoon on the west coast of the volcanic island of Mauritius. The SGD enters Flic en Flac lagoon through a thin blanket of unconsolidated sediment through a fracture system and is concentrated along the ...

  11. Simulation of Wave-Plus-Current Scour beneath Submarine Pipelines

    DEFF Research Database (Denmark)

    Eltard-Larsen, Bjarke; Fuhrman, David R.; Sumer, B. Mutlu

    2016-01-01

    A fully coupled hydrodynamic and morphologic numerical model was utilized for the simulation of wave-plus-current scour beneath submarine pipelines. The model was based on incompressible Reynolds-averaged Navier–Stokes equations, coupled with k-ω turbulence closure, with additional bed and suspen...

  12. Sedimentary characteristics of samples collected from some submarine canyons

    NARCIS (Netherlands)

    Bouma, Arnold H.

    Oriented rectangular cores of 20.3 × 30.5 cm and 45.7 cm high have been collected in a number of submarine canyons off southern California (U.S.A.) and off the southern tip of Baja California (Mexico) for a detailed study of their sedimentary structures. By applying several methods, mainly X-ray

  13. 'Good Hunting': German submarine offensives and South African ...

    African Journals Online (AJOL)

    The first German submarine offensive in South African waters during 1942, Operation Eisbär, was aimed at striking a devastating blow to shipping off the South African coast. By the end of December 1942, an estimated 310 864 tons of shipping had been sunk through Operation Eisbär and the first U-cruiser operation alone.

  14. Cost Estimation Lessons Learned for Future Submarine Acquisition Programs

    Science.gov (United States)

    2010-02-17

    North Carolina and New Mexico 30 General Dynamics Electric Boat “U.S. Navy Awards General Dynamics $14 Billion Contract for Eight Virginia- Class...NAVSEA Program Executive officer, Submarines PMO 450, June 1995. “New SSN Program Life Cycle Cost Estimate.” Naval Center for Cost Analysis: GE-1300

  15. Seismic evidence of a second submarine eruption in the north of El Hierro Island

    Science.gov (United States)

    Ortiz, R.; Berrocoso, M.; de la Cruz-Reyna, S.; Marrero, J. M.; Garcia, A.

    2012-04-01

    From the July 19, 2011 an increase of seismicity, accompanied by a remarkable process of deformation, was detected on the island of El Hierro. This reactivation process, instrumental and scientifically monitored, culminates in the occurrence of a submarine eruption, with the emergence of a strong tremor signal, in the south of the island on October 10, 2011. Both processes (unrest and eruption) have different phases and behaviors clearly evidenced by the deformation and seismicity. This work is the result of an exhaustive analysis of seismic signals from three stations deployed on the island of El Hierro(CTAB and CTIG (IGN) and REST (CSIC)), in order to explain the behavior of the volcanic system responsible for the submarine eruption of Las Calmas sea and its evolution, as well as evidence of a second submarine eruption in the north of the island (ElGolfo). The spectral content of signals from the seismic stations in the north of the island (CTIG and CTAB) and the area around the eruption (REST) has the dominant peak at different frequencies. The amplitude modulations of the seismic noise evolved differently in CTAB and CTIG than REST being particularly significant changes in amplitude and frequency after the occurrence of events of magnitude greater than 4. The evolution of the volcano-tectonic cumulative seismic energy shows the occurrence of two similar eruptive episodes, in which two phases can be distinguished. The first phase of both cycles has a constant rate with seismic events of magnitude less than 3 to reach the energy of 10 ^ 11 Joule. From that moment the magnitude grows rapidly exceeding magnitude 4. In the second phase the seismic events are mainly located in the south of the island, before the onset of visual evidences of the eruption (October 11, 2011) and later (November 2011) the seismic events are mainly located in the north of the island, where no visible signs have been detected. In both cases the appearance or changes in the tremor signal

  16. An ongoing large submarine landslide at the Japan trench

    Science.gov (United States)

    Nitta, S.; Kasaya, T.; Miura, S.; Kawamura, K.

    2013-12-01

    This paper deals with an active submarine landslide on a landward trench slope in the Japan trench. Studied area is located on the upper terrace ranging from 400 to 1200 m in water depth, off Sendai, northeast Japan. We have surveyed in detail the seabed topography using a multi narrow beam (hereafter MBES) and a subbottom profiler (hereafter SBP) during the cruise MR12-E02 of R/V Mirai. The survey lines were 12 lines in N-S, and 3 lines in E-W, and situated in the region from 141°45'E, 37°40'N to 142°33'E, 38°32'N. Moreover, we used multi-channel seismic profile by the cruise KR04-10 of R/V Kairei in the interpretation of the SBP results. In general, horseshoe-shaped depressions of about 100 km wide along the trench slope are arrayed along the Japan trench. It has thought that they were formed by large submarine landslides, but we could not understand critically the relationship between the depressions and the submarine landslides. Based on the survey results, we found signals of an active submarine landslide in the depression as follows. 1) We observed arcuate-shaped lineaments, which are sub-parallel to a horseshoe-shaped depression. The lineaments concentrate in the south region from 38°N at about 20 km wide. These lineaments are formed by deformation structures as anticlines, synclines and normal fault sense displacements. 2) Most of the synclines and anticlines are not buried to form the lineaments. 3) Normal faults cutting about 1 km deep are observed in a multi-channel seismic profile. The normal faults are located just below the arcuate-shaped lineaments, and are tilted eastward being the downslope direction. It indicates a large submarine landslide. We concluded that the arcuate-shaped lineaments were generated by surface sediment movement with the submarine landsliding. We think that the submarine landslide of about 20 km wide and about 1 km thick move continuously down the landward trench slope. This would be the formation process of the horseshoe

  17. Exploring the submarine Graham Bank in the Sicily Channel

    Directory of Open Access Journals (Sweden)

    Mauro Coltelli

    2016-05-01

    Full Text Available In the Sicily Channel, volcanic activity has been concentrated mainly on the Pantelleria and Linosa islands, while minor submarine volcanism took place in the Adventure, Graham and Nameless banks. The volcanic activity spanned mostly during Plio-Pleistocene, however, historical submarine eruptions occurred in 1831 on the Graham Bank and in 1891 offshore Pantelleria Island. On the Graham Bank, 25 miles SW of Sciacca, the 1831 eruption formed the short-lived Ferdinandea Island that represents the only Italian volcano active in historical times currently almost completely unknown and not yet monitored. Moreover, most of the Sicily Channel seismicity is concentrated along a broad NS belt extending from the Graham Bank to Lampedusa Island. In 2012, the Istituto Nazionale di Geofisica e Vulcanologia (INGV carried out a multidisciplinary oceanographic cruise, named “Ferdinandea 2012”, the preliminary results of which represent the aim of this paper. The cruise goal was the mapping of the morpho-structural features of some submarine volcanic centres located in the northwestern side of the Sicily Channel and the temporary recording of their seismic and degassing activity. During the cruise, three OBS/Hs (ocean bottom seismometer with hydrophone were deployed near the Graham, Nerita and Terribile submarine banks. During the following 9 months they have recorded several seismo-acoustic signals produced by both tectonic and volcanic sources. A high-resolution bathymetric survey was achieved on the Graham Bank and on the surrounding submarine volcanic centres. A widespread and voluminous gas bubbles emission was observed by both multibeam sonar echoes and a ROV (remotely operated vehicle along the NW side of the Graham Bank, where gas and seafloor samples were also collected.

  18. Image Noise, CNR, and Detectability of Low-Contrast, Low-Attenuation Liver Lesions in a Phantom: Effects of Radiation Exposure, Phantom Size, Integrated Circuit Detector, and Iterative Reconstruction.

    Science.gov (United States)

    Goenka, Ajit H; Herts, Brian R; Dong, Frank; Obuchowski, Nancy A; Primak, Andrew N; Karim, Wadih; Baker, Mark E

    2016-08-01

    Purpose To assess image noise, contrast-to-noise ratio (CNR) and detectability of low-contrast, low-attenuation liver lesions in a semianthropomorphic phantom by using either a discrete circuit (DC) detector and filtered back projection (FBP) or an integrated circuit (IC) detector and iterative reconstruction (IR) with changes in radiation exposure and phantom size. Materials and Methods An anthropomorphic phantom without or with a 5-cm-thick fat-mimicking ring (widths, 30 and 40 cm) containing liver inserts with four spherical lesions was scanned with five exposure settings on each of two computed tomography scanners, one equipped with a DC detector and the other with an IC detector. Images from the DC and IC detector scanners were reconstructed with FBP and IR, respectively. Image noise and lesion CNR were measured. Four radiologists evaluated lesion presence on a five-point diagnostic confidence scale. Data analyses included receiver operating characteristic (ROC) curve analysis and noninferiority analysis. Results The combination of IC and IR significantly reduced image noise (P < .001) (with the greatest reduction in the 40-cm phantom and at lower exposures) and improved lesion CNR (P < .001). There was no significant difference in area under the ROC curve between detector-reconstruction combinations at fixed exposure for either phantom. Reader accuracy with IC-IR was noninferior at 50% (100 mAs [effective]) and 25% (300 mAs [effective]) exposure reduction for the 30- and 40-cm phantoms, respectively (adjusted P < .001 and .04 respectively). IC-IR improved readers' confidence in the presence of a lesion (P = .029) independent of phantom size or exposure level. Conclusion IC-IR improved objective image quality and lesion detection confidence but did not result in superior diagnostic accuracy when compared with DC-FBP. Moderate exposure reductions maintained comparable diagnostic accuracy for both detector-reconstruction combinations. Lesion detection in the 40

  19. Modeled alongshore circulation and force balances onshore of a submarine canyon

    Science.gov (United States)

    Hansen, Jeff E.; Raubenheimer, Britt; List, Jeffrey H.; Elgar, Steve

    2015-03-01

    Alongshore force balances, including the role of nonlinear advection, in the shoaling and surf zones onshore of a submarine canyon are investigated using a numerical modeling system (Delft3D/SWAN). The model is calibrated with waves and alongshore flows recorded over a period of 1.5 months at 26 sites along the 1.0, 2.5, and 5.0 m depth contours spanning about 2 km of coast. Field observation-based estimates of the alongshore pressure and radiation-stress gradients are reproduced well by the model. Model simulations suggest that the alongshore momentum balance is between the sum of the pressure and radiation-stress gradients and the sum of the nonlinear advective terms and bottom stress, with the remaining terms (e.g., wind stress and turbulent mixing) being negligible. The simulations also indicate that unexplained residuals in previous field-based estimates of the momentum balance may be owing to the neglect of the nonlinear advective terms, which are similar in magnitude to the sum of the forcing (pressure and radiations stress gradients) and to the bottom stress.

  20. Low radiation dose 256-MDCT angiography of the carotid arteries: Effect of hybrid iterative reconstruction technique on noise, artifacts, and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Kondratyev, Evgeny, E-mail: evgenykondratiev@gmail.com; Karmazanovsky, Grigory, E-mail: Karmazanovsky@ixv.ru

    2013-12-01

    To evaluate the effect of hybrid iterative reconstruction on qualitative and quantitative parameters at low dose carotid CTA. Materials and methods: 44 consecutive patients were enrolled in the study. First group (n = 22) was examined under 120 kV 250 mAs, second group (n = 22) – 100 kV 250 mAs. CT images in first group were reconstructed only with the filtered back projection (FBP). CT data in second group were reconstructed both with FBP and three levels of hybrid iterative reconstruction algorithm (iDose). We compared quantitative and qualitative parameters among the two groups and among four different reconstructions in second group. Results: Effective dose in 120 kV and 100 kV group was 7.18 ± 1.19 mSv and 4.14 ± 1.03 mSv, respectively (p < 0.0001). Mean arterial attenuation was about 25% higher in second group (236.5 ± 46 HU vs. 302.6 ± 32.7 HU; p < 0.0001). Image noise at the level of humeral belt was 32.5 ± 12.5 in 100 kV group and 26.3 ± 13.3 in 120 kV (p = 0.115). Average noise decreased when using 3 levels of iDose up to 23.6 ± 6.4, 17.7 ± 5.6 and 13.7 ± 5.1, respectively (p = 0.00001). Mean CNR increased to 10.38 ± 3.87, 14.5 ± 5.21 and 18.32 ± 8.61, respectively (p < 0.05). The presence of artifacts on the level of humeral belt in 120 kV group was 14%, in 100 kV – 41% (p = 0.002). The difference in visual scores between standard and low-dose protocol was significant (p = 0.008). When applying iterative reconstruction the frequency of streak artifacts decreased dramatically (p < 0.0001). Most studies had excellent quality with no artifacts while using highest level of iDose. Conclusion: According to the results of our study low dose CT angiography using hybrid iterative reconstruction may provide sufficient image quality and allows for significant reduction of patient dose.

  1. Noise in Optical Amplifiers

    DEFF Research Database (Denmark)

    Jeppesen, Palle

    1997-01-01

    Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....

  2. Low noise road surfaces

    OpenAIRE

    Bolčina, Matjaž

    2014-01-01

    Noise is everywhere. Noise is a sound that makes people stressful and irritate. It often couses sleep disorders and also health problems like different cardiovascular disorders, hearing loss…In most cases traffic noise is the most disturbing. There are different ways to prevent people from traffic noise like building noise barriers and insulation of facades. However noise barriers and insulation of facades do not prevent noise formation, but are lowering existing noise. Another disadvantage i...

  3. Acoustic response of submarine volcanoes in the Tofua Arc and northern Lau Basin to two great earthquakes

    Science.gov (United States)

    Bohnenstiehl, DelWayne R.; Dziak, Robert P.; Matsumoto, Haru; Conder, James A.

    2014-03-01

    Using a short-baseline hydrophone array, persistent volcanoacoustic sources are identified within the ambient noise field of the Lau Basin during the period between 2009 January and 2010 April. The submarine volcano West Mata and adjacent volcanic terrains, including the northern Matas and Volcano O, are the most active acoustic sources during the 15-month period of observation. Other areas of long-term activity include the Niua hydrothermal field, the volcanic islands of Hunga Ha'apai, Founalei, Niuatoputapu and Niuafo'ou, two seamounts located along the southern Tofua Arc and at least three unknown sites within the northern Lau Basin. Following the great Samoan earthquake on 2009 September 29, seven of the volcanoacoustic sources identified exhibit increases in the rate of acoustic detection. These changes persist over timescales of days-to-months and are observed up to 900 km from the earthquake hypocentre. At least one of the volcanoacoustic sources that did not respond to the 2009 Samoan earthquake exhibits an increase in detection rate following the great Mw 8.8 Chile earthquake that occurred at a distance of ˜9500 km on 2010 February 27. These observations suggest that great earthquakes may have undocumented impacts on Earth's vast submarine volcanic systems, potentially increasing the short-term flux of magma and volcanic gas into the overlying ocean.

  4. Filtering of measurement noise with the 3D reconstruction algorithm

    DEFF Research Database (Denmark)

    Cappellin, Cecilia; Pivnenko, Sergey

    2014-01-01

    Two different antenna models are set up in GRASP and CHAMP, and noise is added to the radiated field. The noisy field is then given as input to the 3D reconstruction of DIATOOL and the SWE coefficients and the far-field radiated by the reconstructed currents are compared with the noise-free results...

  5. [Medical-physiological characteristics of combat training of nuclear-power submarine crews].

    Science.gov (United States)

    Dovgusha, V V; Myznikov, I L; Shalabodov, S A; Bumaĭ, O K

    2009-10-01

    The article presents an observe of general questions of peculiarities of military-professional activity of submarine staff These questions are defining value in ideology of medical supply of submarine troops of NAVY in now-days conditions. The article also presents the statistics of morbidity in long termed sails for last forty years, it's dynamics by different categories of sail staff, on different stages of combat training activity in dependence of perioditation of work cycle of submarine staff The authors have examined modern condition of medical supply of submarines; have presented statistics of quality indexes of health of submarine staff The authors have formed main problems of medical supply of submarines and have proposed ways of their solving on modern stage.

  6. Losses in armoured three-phase submarine cables

    DEFF Research Database (Denmark)

    Ebdrup, Thomas; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2014-01-01

    increases the losses in armoured cables compared to unarmoured cables. In this paper a thorough state of the art analysis is conducted on armour losses in three-phase armoured submarine power cables. The analysis shows that the IEC 60287-1-1 standard overestimates the armour losses which lead...... to the installation of cables with excessive phase conductor cross section. This paper also presents an example of the potential economic benefits of having a better knowledge of the losses introduced by the armour.......The number of offshore wind farms will keep increasing in the future as a part of the shift towards a CO2 free energy production. The energy harvested from the wind farm must be brought to shore, which is often done by using a three-phase armoured submarine power cable. The use of an armour...

  7. Stresses in a submarine topography under ocean waves

    Energy Technology Data Exchange (ETDEWEB)

    Mei, C.C.; McTigue, D.F.

    1984-01-01

    The problem of submarine slope stability is of interest to both offshore engineering and geology. In an uneven topography, the weight above a horizontal plane induces two-dimensional variation in the static stress field. The action of wave pressure, which changes with depth, further introduces excess pore pressure and dynamic stresses in the sea bottom. In the present paper, we combine a simple analytical theory for the static stress by the present authors, and the recent solution by Mei and Foda for wave-induced stresses in a plane poro-elastic sea bed to account for mild bottom slope and wave shoaling, to obtain the effective stress field in a submarine topography under sea waves. Sample results are given for a ridge and a canyon. In particular the dynamic pore pressure and the combined static and dynamic effective stresses are presented. 10 references, 11 figures.

  8. Stresses in a submarine topography under ocean waves

    Energy Technology Data Exchange (ETDEWEB)

    Mei, C.C.; McTigue, D.F.

    1984-09-01

    The problem of submarine slope stability is of interest to both offshore engineering and geology. In an uneven topography, the weight above a horizontal plane induces two-dimensional variation in the static stress field. The action of wave pressure, which changes with depth, further introduces excess pore pressure and dynamic stresses in the sea bottom. In the present paper, we combine a simple analytical theory for the static stress by the present authors, and the recent solution by Mei and Foda for wave-induced stresses in a plane poro-elastic sea bed to account for mild bottom slope and wave shoaling, and obtain the effective stress field in a submarine topography under sea waves. Sample results are given for a ridge and a canyon. In particular, the dynamic pore pressure and the combined static and dynamic effective stresses are presented.

  9. Improving Situational Awareness on Submarines Using Augmented Reality

    Science.gov (United States)

    2008-09-01

    COSO ) are several pages of guidance for the evolution available to the watch officer for reference. There are also Operating Procedures that the watch...officer must follow to ensure the safe ascent to PD. The COSOs are specific to the each CO. The OPs are specific to a class of submarine. The...evolution in the framework described above can provide valuable insight to the capabilities of the proposed system. This of course is a hypothetical

  10. Analysis of SSN 688 Class Submarine Maintenance Delays

    Science.gov (United States)

    2017-06-01

    errors an in-depth analysis into the job-level maintenance is required which is outside the scope of this analysis. 25 2. New Work Causes Late...attempting to determine the cause of this trend. Finally, this thesis proposes a solution to the systematic underestimation of availability durations by...illustrating the inherent error in the current equation and providing a notional equation to remove that error . 14. SUBJECT TERMS Submarine

  11. Submarine Pressure Hull Collapse Considering Corrosion and Penetrations

    Science.gov (United States)

    2010-11-01

    corrosion. Des valeurs de la pression d’écrasement sont calculées pour les diverses dimensions de la zone de corrosion, et ce, dans les cas de présence ou...Research & Development Canada DRDIM Director Research and Development Knowledge and Information Management OOC Out-of-circularity R&D Research...Support SLA (Mr. John Porter) 1 Project Manager , Submarine Scientific Support SLA (LCdr Wade Temple) 9 TOTAL LIST PART I LIST PART II: External

  12. Europe’s Grand Canyon: Nazaré submarine canyon

    OpenAIRE

    Tyler, P.; Amaro, T.; Arzola, R.; Cunha; Stigter, H. de; Gooday, A.; Huvenne, V.; Ingels, J; Kiriakoulakis, K; Lastras, G.; Masson, D.; Oliveira, A.; Pattenden, A.; Vanreusel, A.; van Weering, T.

    2009-01-01

    The Nazare submarine canyon extends similar to 210 km westward from the coast of Portugal, down to a water depth of > 4300 m. The considerable habitat heterogeneity found throughout the canyon is affected by strong currents and high turbidity, especially in the upper parts of the canyon. The canyon morphology comprises steep slopes, scarps, terraces, and overhangs, and a deeply incised thalweg is found in the lower part of the canyon. The seabed within the canyon is composed of varying propor...

  13. Submarine and Autonomous Vessel Proliferation: Implications for Future Strategic Stability at Sea

    Science.gov (United States)

    2012-12-01

    replace the Ohio- class SSBN and Virginia -class SSN to replace the Los Angeles class attack submarine. Although more sophisticated than their...predecessors and with some modifications to demands of the post-Cold War era and (in the Virginia class) an emphasis on littoral conflict, these purchases...Congressional Research Service analyst Amy Woolf observes: “With few submarines in the fleet, the Navy would have to reduce the number of submarines on

  14. The future of the ballistic missile submarine force in the Russian nuclear triad

    OpenAIRE

    Lesiw, Richard T.

    2008-01-01

    Approved for public release; distribution is unlimited This thesis analyzes the current status of the Russian Federation's ballistic missile submarine force. It reviews the history of the ballistic missile submarine force, its current status, and the implementation of plans currently in progress and as well as the advantages and disadvantages of maintaining a ballistic missile submarine force. This thesis also assesses the other two legs of the nuclear triad - the intercontinental balli...

  15. Gender Integration on U.S. Navy Submarines: Views of the First Wave

    Science.gov (United States)

    2015-06-01

    submarines is to perform seek-and-destroy missions on enemy ships and submarines, conduct surveillance and reconnaissance, provide covert troop insertion...not only the missile payload they were designed to carry but also extended periods at sea without resupply. In terms of berthing and sanitary ...officer berthing and sanitary 28 facilities on board Ohio class submarines, however, no significant modifications would be necessary in order to

  16. Navy Virginia (SSN-774) Class Attack Submarine Procurement: Background and Issues for Congress

    Science.gov (United States)

    2016-02-12

    reactors or non- nuclear power sources such as diesel engines or fuel cells. All U.S. Navy submarines are nuclear - powered. A submarine’s use of...the Navy’s plan to design and procure a next - generation ballistic missile submarine called the Ohio Replacement Program or SSBN(X). 26...the next several years require these submarines to use up their nuclear fuel cores more quickly than the Navy now projects, then the amounts of time

  17. Introduction to the special issue on submarine geohazard records and potential seafloor instability

    Directory of Open Access Journals (Sweden)

    Song-Chuen Chen Jia-Jyun Dong

    2018-01-01

    Full Text Available Submarine landslides frequently occur in passive continental margins or active margins (Hampton et al. 1996; Wynn et al. 2000; Mienert et al. 2002; Korup et al. 2007; Twichell et al. 2009; Cukur et al. 2016. Submarine landslides have been studied extensively not only for scientific research but also for submarine geohazards. Submarine landslides could jeopardize marine infrastructures, such as offshore drilling platforms or submarine telecommunication cables, and could even trigger disastrous tsunamis (Bondevik et al. 2005; Harbitz et al. 2006; Hornbach et al. 2007, 2008; Hsu et al. 2008; Su et al. 2012; Tappin et al. 2014; Li et al. 2015. For instance, one disastrous tsunami hitting the coastal area of southwestern Taiwan in 1781 or 1782 was reported (Chen 1830; Hsu 1983; the tsunami event was probably generated by submarine landslides in the offshore area of southwestern Taiwan (Li et al. 2015. Moreover, several submarine landslides triggered by the 2006 Pingtung earthquake have induced turbidity currents off southwest Taiwan and destroyed about 14 submarine telecommunication cables off SW Taiwan (Hsu et al. 2008. The area of southwest Taiwan currently has a dense population (more than 3 million people in total, one deep-water Kaohsiung Port, several tanks of liquefied natural gas and a nuclear power plant on the coast (Fig. 1. Numerous submarine telecommunication cables exist off SW Taiwan. If a considerable tsunami event would hit again the costal area of SW Taiwan, the damage could very serious. Likewise, there are two nuclear power plants on the coast of northern Taiwan (Fig. 2, and the population in northern Taiwan has more than 10 million people. Submarine telecommunication cables also exist off northern Taiwan. In any case, it is important to understand the status of seafloor stability in the offshore areas of SW and NE Taiwan. For that, this special issue of submarine geohazard records and potential seafloor instability is aimed to

  18. Navy Virginia (SSN 774) Class Attack Submarine Procurement: Background and Issues for Congress

    Science.gov (United States)

    2016-10-25

    powered attack submarines (SSNs). The SSNs are general -purpose submarines that can (when appropriately equipped and armed) perform a variety of...signs of tampering. The defective elbow pipe, used to funnel steam from the reactor to the sub’s propulsion turbines and generators , showed evidence of...Congressional Research Service Summary The Navy has been procuring Virginia (SSN-774) class nuclear- powered attack submarines since FY1998. The two Virginia

  19. Fuel-cell-propelled submarine-tanker-system study

    Energy Technology Data Exchange (ETDEWEB)

    Court, K E; Kumm, W H; O' Callaghan, J E

    1982-06-01

    This report provides a systems analysis of a commercial Arctic Ocean submarine tanker system to carry fossil energy to markets. The submarine is to be propelled by a modular Phosphoric Acid Fuel Cell system. The power level is 20 Megawatts. The DOE developed electric utility type fuel cell will be fueled with methanol. Oxidant will be provided from a liquid oxygen tank carried onboard. The twin screw submarine tanker design is sized at 165,000 deadweight tons and the study includes costs and an economic analysis of the transport system of 6 ships. The route will be under the polar icecap from a loading terminal located off Prudhoe Bay, Alaska to a transshipment facility postulated to be in a Norwegian fjord. The system throughput of the gas-fed methanol cargo will be 450,000 barrels per day. The total delivered cost of the methanol including well head purchase price of natural gas, methanol production, and shipping would be $25/bbl from Alaska to the US East Coast. Of this, the shipping cost is $6.80/bbl. All costs in 1981 dollars.

  20. Estimating the empirical probability of submarine landslide occurrence

    Science.gov (United States)

    Geist, Eric L.; Parsons, Thomas E.; Mosher, David C.; Shipp, Craig; Moscardelli, Lorena; Chaytor, Jason D.; Baxter, Christopher D. P.; Lee, Homa J.; Urgeles, Roger

    2010-01-01

    The empirical probability for the occurrence of submarine landslides at a given location can be estimated from age dates of past landslides. In this study, tools developed to estimate earthquake probability from paleoseismic horizons are adapted to estimate submarine landslide probability. In both types of estimates, one has to account for the uncertainty associated with age-dating individual events as well as the open time intervals before and after the observed sequence of landslides. For observed sequences of submarine landslides, we typically only have the age date of the youngest event and possibly of a seismic horizon that lies below the oldest event in a landslide sequence. We use an empirical Bayes analysis based on the Poisson-Gamma conjugate prior model specifically applied to the landslide probability problem. This model assumes that landslide events as imaged in geophysical data are independent and occur in time according to a Poisson distribution characterized by a rate parameter λ. With this method, we are able to estimate the most likely value of λ and, importantly, the range of uncertainty in this estimate. Examples considered include landslide sequences observed in the Santa Barbara Channel, California, and in Port Valdez, Alaska. We confirm that given the uncertainties of age dating that landslide complexes can be treated as single events by performing statistical test of age dates representing the main failure episode of the Holocene Storegga landslide complex.

  1. Pockmark morphology and turbulent buoyant plumes at a submarine spring

    Science.gov (United States)

    Buongiorno Nardelli, B.; Budillon, F.; Watteaux, R.; Ciccone, F.; Conforti, A.; De Falco, G.; Di Martino, G.; Innangi, S.; Tonielli, R.; Iudicone, D.

    2017-09-01

    The input flow of groundwater from the seabed to the coastal ocean, known as Submarine Groundwater Discharge (SGD), has been only recently recognized as an important component of continental margin systems. It potentially impacts physical, chemical and biological marine dynamics. Independently of its specific nature (seepage, submarine springs, etc.) or fluid chemical composition, a SGD is generally characterized by low flow rates, hence making its detection and quantification very difficult, and explaining why it has been somewhat neglected by the scientific community for a long time. Along with the growing interest for SGDs emerged the need for in-situ observations in order to characterize in details how these SGDs behave. In this work, we describe the morphology of a pockmark field, detected in the Southern Tyrrhenian Sea (Mediterranean Sea), and provide observational evidences of the presence of active submarine springs over the coastal shelf area. We describe the effect of the fluid seeps on the water column stratification close to the main plumes and in the neighbouring areas, providing quantitative estimates of the intensity of the turbulent mixing and discussing their potential impact on the seabed morphology and pockmark formation in the context of turbulent buoyant plumes analytical modelling.

  2. Long-term eruptive activity at a submarine arc volcano.

    Science.gov (United States)

    Embley, Robert W; Chadwick, William W; Baker, Edward T; Butterfield, David A; Resing, Joseph A; de Ronde, Cornel E J; Tunnicliffe, Verena; Lupton, John E; Juniper, S Kim; Rubin, Kenneth H; Stern, Robert J; Lebon, Geoffrey T; Nakamura, Ko-ichi; Merle, Susan G; Hein, James R; Wiens, Douglas A; Tamura, Yoshihiko

    2006-05-25

    Three-quarters of the Earth's volcanic activity is submarine, located mostly along the mid-ocean ridges, with the remainder along intraoceanic arcs and hotspots at depths varying from greater than 4,000 m to near the sea surface. Most observations and sampling of submarine eruptions have been indirect, made from surface vessels or made after the fact. We describe here direct observations and sampling of an eruption at a submarine arc volcano named NW Rota-1, located 60 km northwest of the island of Rota (Commonwealth of the Northern Mariana Islands). We observed a pulsating plume permeated with droplets of molten sulphur disgorging volcanic ash and lapilli from a 15-m diameter pit in March 2004 and again in October 2005 near the summit of the volcano at a water depth of 555 m (depth in 2004). A turbid layer found on the flanks of the volcano (in 2004) at depths from 700 m to more than 1,400 m was probably formed by mass-wasting events related to the eruption. Long-term eruptive activity has produced an unusual chemical environment and a very unstable benthic habitat exploited by only a few mobile decapod species. Such conditions are perhaps distinctive of active arc and hotspot volcanoes.

  3. Prediction of V/STOL Noise for Application to Community Noise Exposure

    Science.gov (United States)

    1973-05-01

    A computer program to predict the Effective Perceived Noise Level (EPNL), the tone corrected Perceived Noise Level (PNLT) and the A-Weighted Sound Level (dBA) radiated by a V/STOL vehicle as it flies along a prescribed takeoff, landing, or cruise fli...

  4. A novel positioning method for dual Mach-Zehnder interferometric vibration sensor in submarine cable security application

    Science.gov (United States)

    Xie, Shangran; Zhang, Min; Li, Yanhe; Liao, Yanbiao

    2011-05-01

    Dual Mach-Zehnder interferometric vibration sensor is an appropriate solution for submarine cable security application. While in this application the detected vibration signal is always narrow-bandwidth and short-duration subject to environmental constraints, which makes correlation based vibration positioning algorithm a poor robustness to noise. A preprocessing method focusing on expanding signal 3dB bandwidth before correlation is proposed in purpose of reducing ultimate positioning mean square error. A high pass filter is imposed to enhance the weight of high frequency components by attenuating low frequency main lobe. Field test results indicate a significant positioning error reduction when using this novel method as long as the cutoff frequency of high pass filter is selected in a valid region where positive effect of bandwidth extension is larger than effect of SNR reduction, and MSE reduction value in valid region agrees well with theoretical prediction.

  5. Scientific Ocean Drilling to Assess Submarine Geohazards along European Margins

    Science.gov (United States)

    Ask, M. V.; Camerlenghi, A.; Kopf, A.; Morgan, J. K.; Ocean DrillingSeismic Hazard, P. E.

    2008-12-01

    Submarine geohazards are some of the most devastating natural events in terms of lives lost and economic impact. Earthquakes pose a big threat to society and infrastructure, but the understanding of their episodic generation is incomplete. Tsunamis are known for their potential of striking coastlines world-wide. Other geohazards originating below the sea surface are equally dangerous for undersea structures and the coastal population: submarine landslides and volcanic islands collapse with little warning and devastating consequences. The European scientific community has a strong focus on geohazards along European and nearby continental margins, especially given their high population densities, and long historic and prehistoric record of hazardous events. For example, the Mediterranean is surrounded by very densely-populated coastline and is the World's leading holiday destination, receiving up 30% of global tourism. In addition, its seafloor is criss-crossed by hydrocarbon pipelines and telecommunication cables. However, the governing processes and recurrence intervals of geohazards are still poorly understood. Examples include, but are not limited to, earthquakes and volcanic eruptions along the active tectonic margins of the Mediterranean and Sea of Marmara, landslides on both active and passive margins, and tsunamites and seismites in the sedimentary record that suggest a long history of similar events. The development of geophysical networks, drilling, sampling and long-term monitoring are crucial to the understanding of earthquake, landslide, and tsunami processes, and to mitigate the associated risks in densely populated and industrialized regions such as Europe. Scientific drilling, particularly in the submarine setting, offers a unique tool to obtain drill core samples, borehole measurements and long-term observations. Hence, it is a critical technology to investigate past, present, and possible future influences of hazardous processes in this area. The

  6. A new measurement method for separating airborne and structureborne aircraft interior noise

    Science.gov (United States)

    Mcgary, M. C.; Mayes, W. H.

    1983-01-01

    It is pointed out that interior noise levels of propeller driven aircraft are substantially higher than levels measured for other types of CTOL aircraft. Reduction of interior noise of such aircraft requires a knowledge of the relative importance of the acoustic and structural noise transmission paths. Noise entering the aircraft interior via an acoustic path is the noise radiated by an external noise source (propellers, exhaust noise), which propagates through the acoustic medium (air) and is then transmitted through the aircraft fuselage. This type of incoming noise is referred to as airborne noise. Noise entering the aircraft interior via a structural path is the noise which has its source in the vibrational energy which has been transmitted through the structure from a remote vibrational energy source (engines, wind flutter). This type of incoming noise is referred to as structureborne noise. A new method for separating airborne and structureborne noise is presented. It is based on two-microphone cross spectral acoustic intensity measurements.

  7. Tsunami Generated by a Two-Phase Submarine Debris Flow

    Science.gov (United States)

    Pudasaini, S. P.

    2012-04-01

    The general two-phase debris flow model proposed by Pudasaini (2011) is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model includes several essential physical aspects, including Mohr-Coulomb plasticity for the solid stress, while the fluid stress is modelled as a solid volume fraction gradient enhanced non-Newtonian viscous stress. The generalized interfacial momentum transfer includes the viscous drag, buoyancy, and the virtual mass. The generalized drag covers both the solid-like and fluid-like contributions, and can be applied to linear to quadratic drags. Strong couplings exist between the solid and the fluid momentum transfer. The advantage of the real two-phase debris flow model over classical single-phase or quasi-two-phase models is that by considering the solid (and/or the fluid) volume fraction appropriately, the initial mass can be divided into several (even mutually disjoint) parts; a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This offers a unique and innovative opportunity within a single framework to simultaneously simulate (a) the sliding debris (or landslide), (b) the water lake or ocean, (c) the debris impact at the lake or ocean, (d) tsunami generation and propagation, (e) mixing and separation between the solid and the fluid phases, and (f) sediment transport and deposition process in the bathymetric surface. The new model is applied to two-phase subaerial and submarine debris flows. Benchmark numerical simulations reveal that the dynamics of the debris impact induced tsunamis are fundamentally different than the tsunami generated by pure rock avalanche and landslides. Special attention is paid to study the basic features of the debris impact to the mountain lakes or oceans. This includes the generation, amplification and propagation of the multiple

  8. Searching for structural medium changes during the 2011 El Hierro (Spain) submarine eruption

    Science.gov (United States)

    Sánchez-Pastor, Pilar S.; Schimmel, Martin; López, Carmen

    2017-04-01

    Submarine volcanic eruptions are often difficult to study due to their restricted access that usually inhibits direct observations. That happened with the 2011 El Hierro eruption, which is the first eruption that has been tracked in real time in Canary Islands. For instance, despite the real-time tracking it was not possible to determine the exact end of the eruption. Besides, volcanic eruptions involve many dynamic (physical and chemical) processes, which cause structural changes in the surrounding medium that we expect to observe and monitor through passive seismic approaches. The purpose of this study is to detect and analyse these changes as well as to search for precursory signals to the eruption itself using ambient noise auto and cross-correlations. We employ different correlation strategies (classical and phase cross-correlation) and apply them to field data recorded by the IGN network during 2011 and 2012. The different preprocessing and processing steps are tested and compared to better understand the data, to find the robust signatures, and to define a routine work procedure. One of the problems we face is the presence of volcanic tremors, which cause a varying seismic response that we can not attribute to structural changes. So far, structural changes could not be detected unambiguously and we present our ongoing research in this field.

  9. The near boiling reactor: Conceptual design of a small inherently safe nuclear reactor to extend the operational capability of the Victoria Class submarine

    Science.gov (United States)

    Cole, Christopher J. P.

    Nuclear power has several unique advantages over other air independent energy sources for nuclear combat submarines. An inherently safe, small nuclear reactor, capable of supply the hotel load of the Victoria Class submarines, has been conceptually developed. The reactor is designed to complement the existing diesel electric power generation plant presently onboard the submarine. The reactor, rated at greater than 1 MW thermal, will supply electricity to the submarine's batteries through an organic Rankine cycle energy conversion plant at 200 kW. This load will increase the operational envelope of the submarine by providing up to 28 continuous days submerged, allowing for an enhanced indiscretion ratio (ratio of time spent on the surface versus time submerged) and a limited under ice capability. The power plant can be fitted into the existing submarine by inserting a 6 m hull plug. With its simplistic design and inherent safety features, the reactor plant will require a minimal addition to the crew. The reactor employs TRISO fuel particles for increased safety. The light water coolant remains at atmospheric pressure, exiting the core at 96°C. Burn-up control and limiting excess reactivity is achieved through movable reflector plates. Shut down and regulatory control is achieved through the thirteen hafnium control rods. Inherent safety is achieved through the negative prompt and delayed temperature coefficients, as well as the negative void coefficient. During a transient, the boiling of the moderator results in a sudden drop in reactivity, essentially shutting down the reactor. It is this characteristic after which the reactor has been named. The design of the reactor was achieved through modelling using computer codes such as MCNP5, WIMS-AECL, FEMLAB, and MicroShield5, in addition to specially written software for kinetics, heat transfer and fission product poisoning calculations. The work has covered a broad area of research and has highlighted additional areas

  10. Occupational noise management

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-06-15

    Occupational noise is a frequently encountered on-the-job health hazard. This guide presented the responsibilities and regulatory requirements related to business activities where noise above 80 decibels is present. The guide provided a definition of noise and discussed noise hazards, types of noise, and on-the-job noise exposure. A risk assessment to noise in the work environment was also discussed. A guide to a hearing conservation program was also included. The main purpose of a hearing conservation program is the prevention of noise induced hearing loss for employees exposed to occupational noise. The components of such a program were outlined, with particular reference to noise monitoring; noise exposure control; worker education and training; hearing (audiometric) testing; and annual program review and record keeping. It was concluded that in terms of record keeping, it can be very helpful to file noise exposure assessments, particularly personal exposure measurements, with hearing test records to facilitate for future reference. refs., appendices.

  11. The Impact of the General Board of the Navy on Interwar Submarine Design

    Science.gov (United States)

    2009-06-12

    Navy had developed the Gato class submarine, which was successful independently operating in the vast Pacific Ocean in support of War Plan Orange. The...development of the Gato class submarine, which was successful independently operating in the vast Pacific Ocean in support of War Plan Orange. The...

  12. Procurements by the Non-Acoustic Anti-Submarine Warfare Program Through the Environmental Technologies Laboratory

    Science.gov (United States)

    1994-06-14

    General, DoD, on contract offloading, including Report No. 93-068, " Procurement of Services for the Non-Acoustic Anti-Submarine Warfare Program...contract administration in response to Audit Report No. 93-042. Report No. 93-068, " Procurement of Services for the Non-Acoustic Anti- Submarine Warfare

  13. Study on the locational criteria for submarine rock repositories of low and medium level radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G. H.; Kang, W. J.; Kim, T. J. and others [Chungnam National Univ., Taejon (Korea, Republic of)

    1992-01-15

    Submarine repositories have significant advantages over their land counterparts locating close to the areas of daily human activities. Consequently, the construction of submarine repositories on the vast continental shelves around Korean seas is considered to be highly positive. In this context, the development of locational criteria primarily targeting the safety of submarine rock repositories is very important.The contents of the present study are: analyzing characteristics of marine environment: Search of potential hazards to, and environmental impact by, the submarine repositories; Investigation of the oceanographic, geochemical, ecological and sedimentological characteristics of estuaries and coastal seas. Locating potential hazards to submarine repositories by: Bibliographical search of accidents leading to the destruction of submarine structures by turbidity currents and other potentials; Review of turbidity currents. Consideration of environmental impact caused by submarine repositories: Logistics to minimize the environmental impacts in site selection; Removal and dispersion processes of radionuclides in sea water. Analyses of oceanographical characteristics of, and hazard potentials in, the Korean seas. Evaluation of the MOST 91-7 criteria for applicability to submarine repositories and the subsequent proposition of additional criteria.

  14. Submarine landslides on the north continental slope of the South China Sea

    Science.gov (United States)

    Wang, Weiwei; Wang, Dawei; Wu, Shiguo; Völker, David; Zeng, Hongliu; Cai, Guanqiang; Li, Qingping

    2018-02-01

    Recent and paleo-submarine landslides are widely distributed within strata in deep-water areas along continental slopes, uplifts, and carbonate platforms on the north continental margin of the South China Sea (SCS). In this paper, high-resolution 3D seismic data and multibeam data based on seismic sedimentology and geomorphology are employed to assist in identifying submarine landslides. In addition, deposition models are proposed that are based on specific geological structures and features, and which illustrate the local stress field over entire submarine landslides in deep-water areas of the SCS. The SCS is one of the largest fluvial sediment sinks in enclosed or semi-enclosed marginal seas worldwide. It therefore provides a set of preconditions for the formation of submarine landslides, including rapid sediment accumulation, formation of gas hydrates, and fluid overpressure. A new concept involving temporal and spatial analyses is tested to construct a relationship between submarine landslides and different time scale trigger mechanisms, and three mechanisms are discussed in the context of spatial scale and temporal frequency: evolution of slope gradient and overpressure, global environmental changes, and tectonic events. Submarine landslides that are triggered by tectonic events are the largest but occur less frequently, while submarine landslides triggered by the combination of slope gradient and over-pressure evolution are the smallest but most frequently occurring events. In summary, analysis shows that the formation of submarine landslides is a complex process involving the operation of different factors on various time scales.

  15. The risk of hydrogen explosion in a submarine p.I Catalytic combustion of hydrogen

    Directory of Open Access Journals (Sweden)

    Kłos Ryszard

    2016-09-01

    Full Text Available The series of articles discuss issues related to conducting high risk projects on the example of modernisation of hydrogen incinerators on a submarine. The article depicts a technical problem situation connected with catalytic hydrogen combustion on a submarine.

  16. Inhibitory noise

    Directory of Open Access Journals (Sweden)

    Alain Destexhe

    2010-03-01

    Full Text Available Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron's input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory noise. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.

  17. Noise-Measuring Method

    DEFF Research Database (Denmark)

    Diamond, J. M.

    1965-01-01

    A noise-measuring method based on the use of a calibrated noise generator and an output meter with a special scale is described. The method eliminates the effect of noise contributions occurring in the circuits following the device under test.......A noise-measuring method based on the use of a calibrated noise generator and an output meter with a special scale is described. The method eliminates the effect of noise contributions occurring in the circuits following the device under test....

  18. Post-eruptive Submarine Terrace Development of Capelinhos, Azores

    Science.gov (United States)

    Zhongwei Zhao, Will; Mitchell, Neil; Quartau, Rui; Tempera, Fernando; Bricheno, Lucy

    2017-04-01

    Erosion of the coasts of volcanic islands by waves creates shallow banks, but how erosion proceeds with time to create them and how it relates to wave climate is unclear. In this study, historical and recent marine geophysical data collected around the Capelinhos promontory (western Faial Island, Azores) offer an unusual opportunity to characterize how a submarine terrace developed after the eruption. The promontory was formed in 1957/58 during a Surtseyan eruption that terminated with extensive lava forming new rocky coastal cliffs. Historical measurements of coastline position are supplemented here with coastlines measured from 2004 and 2014 Google Earth images in order to characterize coastline retreat rate and distance for lava- and tephra-dominated cliffs. Swath mapping sonars were used to characterize the submarine geometry of the resulting terrace (terrace edge position, gradient and morphology). Limited photographs are available from a SCUBA dive and drop-down camera deployments to ground truth the submarine geomorphology. The results reveal that coastal retreat rates have decreased rapidly with the time after the eruption, possibly explained by the evolving resistance to erosion of cliff base materials. Surprisingly, coastline retreat rate decreases with terrace width in a simple inverse power law with terrace width. We suspect this is only a fortuitous result as wave attenuation over the terrace will not obviously produce the variation, but nevertheless it shows how rapidly the retreat rate declines. Understanding the relationship between terrace widening shelf and coastal cliff retreat rate may be more widely interesting if they can be used to understand how islands evolve over time into abrasional banks and guyots.

  19. Maximizing the probability an aerial anti-submarine torpedo detects its target

    Science.gov (United States)

    Wang, Zhi-Jie

    2009-06-01

    As a result of the high speed of anti-submarine patrol aircraft as well as their wide range, high efficiency and other characteristics, aerial torpedoes released by anti-submarine patrol aircraft have become the key anti submarine tool. In order to improve operational efficiency, a deep study was made of the target detection probabilities for aerial torpedoes released by anti-submarine patrol aircraft. The operational modes of aerial torpedoes were analyzed and mathematical-simulation models were then established. The detection probabilities of three attacking modes were then calculated. Measures were developed for improving low probabilities of detection when attacking a probable target position. This study provides an important frame of reference for the operation of aerial torpedo released by anti-submarine patrol aircraft.

  20. Main devices design of submarine oil-water separation system

    Science.gov (United States)

    Cai, Wen-Bin; Liu, Bo-Hong

    2017-11-01

    In the process of offshore oil production, in order to thoroughly separate oil from produced fluid, solve the environment problem caused by oily sewage, and improve the economic benefit of offshore drilling, from the perspective of new oil-water separation, a set of submarine oil-water separation devices were designed through adsorption and desorption mechanism of the polymer materials for crude oil in this paper. The paper introduces the basic structure of gas-solid separation device, periodic separation device and adsorption device, and proves the rationality and feasibility of this device.

  1. Submarine glaciated landscapes of central and northern British Columbia, Canada

    Science.gov (United States)

    Shaw, John; Lintern, Gwyn

    2015-04-01

    Recent systematic multibeam sonar mapping and ground-truthing surveys in the fjords and coastal waters of central and northern British Columbia, Canada, provide information on glacial processes associated with the Cordilleran Ice Sheet, and also on postglacial processes that have strongly modified the glacial terrain. During the last glacial maximum, ice covered the Coast Range, except for nunataks. Convergent streamlined glacial landforms in the Strait of Georgia testify to a strong flow of ice towards the southeast, between Vancouver Island and the mainland. During ice retreat, thick deposits of acoustically stratified glaciomarine mud were deposited in glacially over deepened basins. Retreat through the Douglas Channel fjord system was punctuated by still stands, resulting in a series of submarine moraines. Postglacial processes have created a suite of landforms that mask the primary glacial terrain: 1) Fjord floors host thick deposits of acoustically transparent postglacial mud with highly variable distribution: banks up to 80-m thick are commonly adjacent to erosional zones with glaciomarine mud exposed at the seafloor; 2) In this region of high precipitation and snowpack melt, numerous cone-shaped Holocene fan deltas developed on the fjord sidewalls transport coarse sediment to the fjord floors. Larger deltas are developed at fjord heads, notably at Kitimat and Kildala; 3) Submarine slope failures in this tectonically active area have resulted in a suite of mass transport deposits on sidewalls and fjord floors. The very large submarine slope failures at Camano Sound and KitKat Inlet occurred on the steep, rear facets of large transverse moraines, and involved the failure of glaciomarine sediment that moved into deeper basins, perhaps as a retrogressive failure. The ages of these events are unknown, although the presence of postglacial mud in the slide scar at Caamano suggests that the event at that location occurred in the late glacial or early Holocene. Also

  2. Micro-tunneling as an alternative to submarine cable

    Energy Technology Data Exchange (ETDEWEB)

    Russo, D.A. [Seattle City Light, WA (United States); Hansen, D. [CH2M Hill, Bellevue, WA (United States)

    1994-12-31

    The geography that gives Seattle its beauty can pose unique challenges for the engineers attempting to provide service to the customers who live near or upon these features. Steep, wooded hills and greenbelts create familiar problems of construction and right-of-way maintenance. The waterways and adjoining shoreline zones present a more difficult set of requirements. When Seattle City Light determined it was necessary to install 2-26 KV feeders across the Salmon Bay waterway, they discovered that submarine cables could not be used. Shallow angle directional drilling and micro-tunneling were examined and it was fond that a microtunneled duct bank was the best method to use.

  3. On the prediction of impact noise, V: The noise from drop hammers

    Science.gov (United States)

    Richards, E. J.; Carr, I.; Westcott, M.

    1983-06-01

    In earlier papers in this series, the concepts of "acceleration" and "ringing" noise have been studied in relation to impact machines, and values of radiation efficiency have been obtained for the various types of structural components. In the work reported in this paper the predicted and measured noise radiation from a drop hammer, both in full-scale and in {1}/{3}- scale model form, were examined. It is found that overall noise levels ( Leq per event) can be predicted from vibration measurements to within ± 1·5 dB, and to within ±2·5 dB in one-third octave bands. In turn this has permitted noise reduction techniques to be examined by studies of local component vibration levels rather than overall noise, a method which provides considerable enlightenment at the design stage. It is shown that on one particular drop hammer, the noise energy is shared surprisingly uniformly over four or five sources, and that when these have been reduced, the overall noise reduction is severely limited by the "acceleration" noise from the "tup" or "hammer" itself. As this is difficult to eliminate without a basic change in forging technology, it follows that "tup" enclosure or modification of the sharpness of the final "hard" impact are the only means available for any serious noise reduction. Also indicated is the reliability of using model techniques, suitably scaled in frequency and impulse magnitude, in developing machinery with impact characteristics.

  4. Evaluation of Littoral Combat Ships for Open-Ocean Anti-Submarine Warfare

    Science.gov (United States)

    2016-03-01

    acoustic tiles , which provide similar radiated noise reduction benefits (Global Security 2011). Figure 20. Master Air System as Shown on Ship’s Hull...http://www.washingtontimes.com/news/2006/nov/13/20061113-121539- 3317r/?page=all. Global Security. 2011. “ Acoustic Tiles .” December 30. http...the Current LCS ....................................................23 D. CURRENT SYSTEMS IN LCS ASW MISSION PACKAGE ............25 E. ACOUSTIC MODEL

  5. Seismicity and sedimentation rate effects on submarine slope stability

    Science.gov (United States)

    Ten Brink, U. S.; Andrews, B. D.; Miller, N. C.

    2016-12-01

    Large submarine mass-transport scars are commonly observed on continental margins, but are noticeably less abundant on margins that experience frequent earthquakes than on those that seldom experience them. This is a surprising observation, given that horizontal acceleration from earthquakes and associated strength loss from cyclic loading and liquefaction are commonly thought to provide the primary triggers for inducing failures and subsequent mass movements. Mapping submarine failure scars in ten margins worldwide, we find decreasing scar abundance with both increasing frequency of earthquakes and decreasing sedimentation rate. The decrease in scar abundance is interpreted to represent increasing slope stability. The increase in stability is non linear (power law with btectonic activity (salt diapirs, seamount subduction, etc.) leads to relatively rapid oversteepening of the slope, implying that the morphology of most margins is in fact, stable over many earthquake cycles. Note that the above correlation averages scar area and sedimentation rate over entire margin areas. Variations in sedimentation rate with time, such as over glacial-interglacial cycles, and intra-margin variations in seismic attenuation, sedimentation rate, composition, and pore pressure, have likely affected the abundance of slope failures in time and space.

  6. An Automatic Procedure for the Quantitative Characterization of Submarine Bedforms

    Directory of Open Access Journals (Sweden)

    Massimo Di Stefano

    2018-01-01

    Full Text Available A model for the extraction and quantitative characterization of submarine landforms from high-resolution digital bathymetry is presented. The procedure is fully automated and comprises two parts. The first part consists of an analytical model which extracts quantitative information from a Digital Elevation Model in the form of objects with similar parametric characteristics (terrain objects. The second part is a rule-based model where the terrain objects are reclassified into distinct landforms with well-defined three dimensional characteristics. For the focus of this work, the quantitative characterization of isolated dunes (height greater than 2 m is used to exemplify the process. The primary metrics used to extract terrain objects are the flatness threshold and the search radius, which are then used by the analytical model to identify the feature type. Once identified as dunes, a sequence of spatial analysis routines is applied to identify and compute metrics for each dune including length, height, width, ray of curvature, slope analysis for each stoss and lee side, and dune symmetry. Dividing the model into two parts, one scale-dependent and another centered around the shape of the landform, makes the model applicable to other submarine landforms like ripples, mega-ripples, and coral reefs, which also have well-defined three-dimensional characteristics.

  7. Fin propulsion on a human-powered submarine

    Science.gov (United States)

    Anderson, Iain A.; Pocock, Benjamin; Harbuz, Antoni; Algie, Cam; Vochezer, Daniel; Chao, Ryan; Lu, Benjamin

    2015-03-01

    Nearly all surface and underwater vessels are driven by screw propulsion; ideal for coupling to rotary engines and well understood after over a century of development. But most aquatic creatures use fins for swimming. Although there are sound evolutionary reasons why fish have fins and not propellers, they are nevertheless agile, fast and efficient. Although fish-like robots such as the MIT Robotuna are providing good insight into fin-based swimming there are advantages for using humans in the experimental device. Like an airplane test pilot they can write crash reports. We present preliminary observations for the human powered finned submarine: Taniwha. The sub participated in the 2nd European International Submarine races in Gosport UK where it received a trophy for "Best Non-Propeller Performance". Two sets of Hobie Mirage fin drives fixed to the upper and lower rear surfaces of the sub are pedaled by the pilot. The pilot also has two levers at the front, one to pitch a pair of dive planes and one for yawing a large rudder. Good speed, we estimate to be greater than 6 m/s is possible with these fins although we haven't explored their full potential. Straying too near the surface or bottom can lead to an instability, synonymous to a stall, such that control is lost. The mechanism for this will be discussed and solutions offered. Fish are 400 million years in front of us but one day we'll catch them.

  8. A submarine fan in the Mesa Central, Mexico

    Science.gov (United States)

    Silva-Romo, G.; Arellano-Gil, J.; Mendoza-Rosales, C.; Nieto-Obregón, J.

    2000-10-01

    The contact between the Guerrero and Sierra Madre tectonostratigraphic terranes has been proposed to lie in the Mesa Central, east of the city of Zacatecas. Marine Triassic units have been assigned to the Guerrero Terrane. It is here proposed that this contact occurs to the west of the city of Zacatecas and the Triassic marine sequence assigned to the Sierra Madre Terrane. We analyzed the stratigraphic record and structural features of pre-Late Jurassic sequences at four localities in the Mesa Central. They contain a marine turbiditic Triassic unit, which includes La Bellena, Taray, and Zacatecas Formations, and a continental unit of probable Middle Jurassic age. Triassic sandstones were derived from a cratonic area, without the influence of arc volcanism. The sequences were affected by two phases of deformation. The Triassic formations are unconformably overlain by a continental volcano-sedimentary sequence that contains fragments of sandstones derived from the underlying unit. Sedimentologic characteristics of the Triassic unit fit a submarine fan model. The submarine fan developed at the continental margin of Pangaea during Triassic times. Turbidite associations in the San Rafael Area indicate a middle fan depositional environment, while in the Real de Catorce Area, they correspond to the distal part (basin plain facies). At La Ballena and Zacatecas the turbidite associations occur in the middle part and perhaps the external part of the fan.

  9. Feasibility study of submarine diesel exhaust valve interspace coating application

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, W.; Zhou, M.; Bibby, D.; Huang, J.

    2008-05-15

    This document described a feasibility study conducted to evaluate surface coating systems applied to the surface of a diesel exhaust valve interspace on a VICTORIA Class submarine. A series of laboratory studies were conducted to determine the physical characteristics of the coatings, which will be subjected to high service temperatures, diesel exhaust gas, and seawater. The valves were made of Q1N steel castings. The surface coatings were designed to provide corrosion resistance and thermal protection to the valves. As part of the study, a survey was conducted on various state-of-the-art surface coating systems. Coatings were rated on their ability to protect the Q10 steel surface from corrosion, high temperatures and seawater. An additional requirement was that the coatings should not produce high amounts of hydrogen. Plating trials were conducted with a nickel-based alloy (Ni-Cu-P) placed on Q1N steel substrates with a hypophosphite reducing agent. The results of X-ray diffraction (XRD) analyses suggested that the coatings can also be used to protect the external surfaces of various submarine components. 54 refs., 4 tabs., 10 figs.

  10. Third party liability of nuclear installation decommissioning with Russian nuclear submarines as an example: insurance versus technologies

    Energy Technology Data Exchange (ETDEWEB)

    Gavrilov, S.D. [PREKSAT Ltd., Moscow (Russian Federation); Derevyankin, A.A. [Reseaarch and Development Institute of Nuclear Power Engineering, Moscow (Russian Federation); Khamyanov, L.P. [All-Russian Research Institute on NPP Operation, Moscow (Russian Federation); Kovalenko, V.N. [Ministry for Nuclear Energy Of Russian, Moscow (Russian Federation); Kovalivich, O.M. [Research and Technological Center for Nuclear and Radiation Safety of Supervisory, Nuclear Energy State Commitee of Russia, Moscow (Russian Federation); Smirnov, P.L. [Nuclear Safety Institute of Russian Academy of Sciences, Moscow (Russian Federation)

    2001-07-01

    Third party and environment of civil liability damage caused by incidents at military nuclear installations, for instance at decommissioned NPS (nuclear powered submarines), may be divided into three main trends: -) Liability of NPS without high-enriched irradiated nuclear fuel (SNF) for its self-submersion (radiation incident); -) Liability of NPS with SNF aboard for its self-submersion (radiation incident); and -) Liability of floating NPS for its SNF discharge (nuclear accident). Without step-by-step transition from the Russian Federation guaranties to insurance and making allowance for liability limits according to the Vienna Convention approach, the sizes of the financial guarantee for the civil liability of the NPS owner (Russian state), in US dollars of 2000, are approximately assessed as the following: -) storing decommissioned NPS or a floating module without SNF - from 12 to 25 thousand dollars per year (per one submarine or module); -) storing decommissioned NPS with SNF inside reactors cores - from 25 to 40 thousand dollars per year; -) assembly-by-assembly removing SNF from reactors' core of decommissioned NPS - up to 1.5 million dollars for undamaged reactor per the discharging period; -) SNF removing within reactor using the filled in-space reactor's core by liquid-phased hardened or dispersed solid-phase materials from decommissioned NPS - from 30 to 50 thousand dollars for undamaged reactor per the discharging period. Both rates and sums for NPS with damaged reactors are to be estimated for the each damaged reactor and NPS at all. It is necessary to perform the measures reducing the risk of nuclear accidents of NPS with undamaged SNF and NPS with damaged reactors in possibly short time. It will allow not only to cut risks by ten times and more, but also to accumulate necessary insurance reserves faster. These measures can be partially or completely executed using the preventing measures reserves assigned to all decommissioned Russian NPS

  11. Non-Markovian noise

    Energy Technology Data Exchange (ETDEWEB)

    Fulinski, A. (Institute of Physics, Jagellonian University, Reymonta 4, PL-30-059 Krakow (Poland))

    1994-10-01

    The properties of non-Markovian noises with exponentially correlated memory are discussed. Considered are dichotomic noise, white shot noise, Gaussian white noise, and Gaussian colored noise. The stationary correlation functions of the non-Markovian versions of these noises are given by linear combinations of two or three exponential functions (colored noises) or of the [delta] function and exponential function (white noises). The non-Markovian white noises are well defined only when the kernel of the non-Markovian master equation contains a nonzero admixture of a Markovian term. Approximate equations governing the probability densities for processes driven by such non-Markovian noises are derived, including non-Markovian versions of the Fokker-Planck equation and the telegrapher's equation. As an example, it is shown how the non-Markovian nature changes the behavior of the driven linear process.

  12. Occupational stress in submariners: the impact of isolated and confined work on psychological well-being.

    Science.gov (United States)

    Brasher, Kate S; Dew, Angela B C; Kilminster, Shaun G; Bridger, Robert S

    2010-03-01

    This study aimed to identify work-related and personal factors associated with occupational stress in submariners. Work and well-being questionnaires were distributed to 219 male submariners (mean age 34 years), as part of a larger cohort study involving a stratified sample of 4951 Royal Navy (RN) personnel. The stress rate in submariners was 40%; significantly higher than the stress rate in the general RN, although once demographic factors were controlled for in a matched control sample, this difference was no longer significant. A summary model accounted for 49% of the variance in submariner stress, with key differences emerging between the occupational factors associated with stress in submariners and in the general RN. The longitudinal nature of this study permits stress in submariners to be monitored over 5 years, which will provide valuable insights into the chronicity of stress in this specialised occupational group. STATEMENT OF RELEVANCE: This paper contributes to the current literature on the negative impact of working in isolated conditions. It is demonstrated that occupational stress in submarines can be partially explained using current theories of stress in the workplace. However, the constraints of a restricted environment introduce additional factors which can also be associated with occupational stress.

  13. Measuring currents in submarine canyons: technological and scientific progress in the past 30 years

    Science.gov (United States)

    Xu, J. P.

    2011-01-01

    The development and application of acoustic and optical technologies and of accurate positioning systems in the past 30 years have opened new frontiers in the submarine canyon research communities. This paper reviews several key advancements in both technology and science in the field of currents in submarine canyons since the1979 publication of Currents in Submarine Canyons and Other Sea Valleys by Francis Shepard and colleagues. Precise placements of high-resolution, high-frequency instruments have not only allowed researchers to collect new data that are essential for advancing and generalizing theories governing the canyon currents, but have also revealed new natural phenomena that challenge the understandings of the theorists and experimenters in their predictions of submarine canyon flow fields. Baroclinic motions at tidal frequencies, found to be intensified both up canyon and toward the canyon floor, dominate the flow field and control the sediment transport processes in submarine canyons. Turbidity currents are found to frequently occur in active submarine canyons such as Monterey Canyon. These turbidity currents have maximum speeds of nearly 200 cm/s, much smaller than the speeds of turbidity currents in geological time, but still very destructive. In addition to traditional Eulerian measurements, Lagrangian flow data are essential in quantifying water and sediment transport in submarine canyons. A concerted experiment with multiple monitoring stations along the canyon axis and on nearby shelves is required to characterize the storm-trigger mechanism for turbidity currents.

  14. assessment of noise pollutio noise pollutio noise pollution

    African Journals Online (AJOL)

    eobe

    This study examine. This study examined noise pollution pollution pollution from sawmillin from sawmillin using HD600 digital data l using HD600 digital data logging sound level me ogging sound level me designed to elicit noise related information. The res sawmills was 58.1 sawmills was 58.1-64.86 dB(A) while machine ...

  15. assessment of noise pollutio noise pollutio noise pollution

    African Journals Online (AJOL)

    eobe

    related ailments such as tinnitus (96.6%), headache (86.6%) se prevention and control strategies are suggested in additio. , education, and enforcement of noise regulations. , education, and enforcement of noise regulations. machine, workers, impacts. , particularly at global concern as strong some high-ranking health.

  16. Aircraft engine noise

    Science.gov (United States)

    Kennepohl, F.

    An overview of the main aircraft engine noise sources is given. Special emphasis is devoted to turbomachinery/rotor noise, which plays an important role in all engine concepts appropriate to regional aircraft, such as turbofans, propellers, or new propfan engine concepts. The noise generating mechanisms, including propagation within the engine, and calculation methods used are described. Noise reduction methods are considered, with emphasis on cutoff design of turbomachines. Some noise features of counter rotating propellers and swept rotor blades are mentioned.

  17. An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.; /SLAC

    2006-12-11

    The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed.

  18. Prediction of nuclear submariner adaptability from autonomic indices and Rorschach Inkblot responses. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Weybrew, B.B.; Molish, H.B.

    1986-09-09

    To identify the most valid predictors of submariner adaptability, the authors derived 23 indices from the responses of 170 nuclear submariners to the Rorschach Inkblot Test, 11 measures of Autonomic Nervous System (ANS) reactivity to contrived stress, and five adjustment criteria. Factor analysis of this 39x39 correlation matrix yielded two Rorschach Factors, one of which correlated with three criterion dimensions. Two unique factors were also discovered, one, a structured ANS factor, and the other, a complex criterion scale. Selected Rorschach scores and, to a lesser extent, certain ANS indices emanating from this study, may be usefully-valid predictors of the adaptability of nuclear submariners during long patrols.

  19. Marine litter in submarine canyons of the Bay of Biscay

    Science.gov (United States)

    van den Beld, Inge M. J.; Guillaumont, Brigitte; Menot, Lénaïck; Bayle, Christophe; Arnaud-Haond, Sophie; Bourillet, Jean-François

    2017-11-01

    Marine litter is a matter of increasing concern worldwide, from shallow seas to the open ocean and from beaches to the deep-seafloor. Indeed, the deep sea may be the ultimate repository of a large proportion of litter in the ocean. We used footage acquired with a Remotely Operated Vehicle (ROV) and a towed camera to investigate the distribution and composition of litter in the submarine canyons of the Bay of Biscay. This bay contains many submarine canyons housing Vulnerable Marine Ecosystems (VMEs) such as scleractinian coral habitats. VMEs are considered to be important for fish and they increase the local biodiversity. The objectives of the study were to investigate and discuss: (i) litter density, (ii) the principal sources of litter, (iii) the influence of environmental factors on the distribution of litter, and (iv) the impact of litter on benthic communities. Litter was found in all 15 canyons and at three sites on the edge of the continental shelf/canyon, in 25 of 29 dives. The Belle-île and Arcachon Canyons contained the largest amounts of litter, up to 12.6 and 9.5 items per 100 images respectively. Plastic items were the most abundant (42%), followed by fishing-related items (16%). The litter had both a maritime and a terrestrial origin. The main sources could be linked to fishing activities, major shipping lanes and river discharges. Litter appeared to accumulate at water depths of 801-1100 m and 1401-1700 m. In the deeper of these two depth ranges, litter accumulated on a geologically structured area, accounting for its high frequency at this depth. A larger number of images taken in areas of coral in the shallower of these two depth ranges may account for the high frequency of litter detection at this depth. A larger number of litter items, including plastic objects in particular, were observed on geological structures and in coral areas than on areas of bare substratum. The distribution of fishing-related items was similar for the various types of

  20. Particle sedimentation and diffusive convection in submarine clouds

    Science.gov (United States)

    Carazzo, G.; Jellinek, M.; Turchyn, A. V.

    2013-12-01

    The longevity of submarine plumes generated by the release of hydrothermal fluids during crustal rupturing or by the rapid cooling of an erupting lava flow constrains the input of crustal-derived elements into the deep-ocean. Decades of observations of episodic "event plumes" suggest that a key process governing the dynamics of a submarine cloud spreading out laterally from a buoyant rising plume is the production of internal layering. Here, we use geological data on submarine clouds and a new experimental apparatus producing at laboratory scale turbulent, hot particle-laden plumes and clouds to show that this layering occurs where particle diffusive convection driven by the differential diffusion of heat and small mineral precipitates gives rise to a large scale double diffusive instability. We show that this "particle diffusive convection" can extend the longevity of an event plume to two years after its emplacement, allowing iron-sulfide minerals to dissolve and deliver iron to the deep-ocean. The very long residence time imposed by diffusive convective effects does not allow iron-oxide minerals to dissolve but may lead to the formation of iron-rich sediments at large distances from the point of emission. We develop a new theoretical model that includes both sedimentation and dissolution processes to quantify the potential amount of iron produced by the dissolution of iron-sulfide minerals settling through the cloud by diffusive convection. A key prediction is that hydrothermal systems could provide 75% of the global budget of dissolved iron in the deep-ocean. The consideration of scale-basin variations suggests that the Southern Hemisphere is probably the most impacted by hydrothermal iron, consistent with observations and global ocean models. Photographs showing the typical evolution of a lab-scale turbulent, hot particle-laden plume. At stage 1, the buoyant plume reaches a level of neutral buoyancy and spreads out laterally forming a neutrally buoyant cloud

  1. Hawaiian submarine manganese-iron oxide crusts - A dating tool?

    Science.gov (United States)

    Moore, J.G.; Clague, D.A.

    2004-01-01

    Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measured on samples collected since 1965 on the Hawaiian Ridge from 140 dive or dredge localities. Fifty-nine (42%) of the sites were collected in 2001 by remotely operated vehicles (ROVs). The thinner crusts on many samples apparently result from post-depositional breakage, landsliding, and intermittent burial of outcrops by sediment. The maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site. The measurements show an irregular progressive thickening of the crusts toward the northwest-i.e., progressive thickening toward the older volcanic features with increasing distance from the Hawaiian hotspot. Comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust-growth rate of about 2.5 mm/m.y. The thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes, but also provides specific age estimates of volcanic and landslide deposits. The data indicate that some of the landslide blocks within the south Kona landslide are the oldest exposed rock on Mauna Loa, Kilauea, or Loihi volcanoes. Crusts on the floors of submarine canyons off Kohala and East Molokai volcanoes indicate that these canyons are no longer serving as channelways for downslope, sediment-laden currents. Mahukona volcano was approximately synchronous with Hilo Ridge, both being younger than Hana Ridge. The Nuuanu landslide is considerably older than the Wailau landslide. The Waianae

  2. Newly recognized submarine slide complexes in the southern California Bight

    Science.gov (United States)

    Conrad, J. E.; Lee, H. J.; Edwards, B. D.; McGann, M.; Sliter, R. W.

    2012-12-01

    New high-resolution bathymetric and seismic-reflection surveys have imaged large (7) individual overlapping slides along the western margin of Santa Cruz Basin (SCB slide); 2) a series of slumps and slide scars on the slope south of San Pedro shelf (SPS slide); and 3) a slope failure along the shelf edge in northern San Diego County, termed the Del Mar slide. The SCB slide complex extends for 30 km along the western slope of Santa Cruz Basin, with debris lobes extending 5-8 km into the basin. Head scarps of some of these slides are 50-75 m high. The SPS slide complex also appears to consist of multiple slides, which roughly parallel the Palos Verdes Fault and the San Gabriel Canyon submarine channel on the shelf edge and slope south of San Pedro shelf. Slide deposits associated with this complex are only partially mapped due to limited high-resolution bathymetric coverage, but extend to the south in the area SW of Lasuen Knoll. Seismic-reflection profiles show that some of these deposits are up to 20 m thick. The Del Mar slide is located about 10 km north of La Jolla Canyon and extends about 6 km along the shelf edge. The head scarp lies along the trend of a branch of the Rose Canyon Fault Zone. Radiocarbon ages of sediment overlying this slide indicate the Del Mar slide is approximately 12-16 ka. These large slide complexes have several characteristics in common. Nearly all occur in areas of tectonic uplift. All of the complexes show evidence of recurrent slide activity, exhibiting multiple headwall scarps and debris lobes, and where available, high-resolution seismic-reflection profiles of these slide areas provide evidence of older, buried mass transport deposits. Assuming typical sedimentation rates, the recurrence interval of major slide events appears to be on the order of tens of thousands of years. Most of the slide complexes do not appear to be located in areas of high sediment input. The SCB and Del Mar slides are in areas receiving relatively small

  3. Multi-scale evaluations of submarine groundwater discharge

    Directory of Open Access Journals (Sweden)

    M. Taniguchi

    2015-03-01

    Full Text Available Multi-scale evaluations of submarine groundwater discharge (SGD have been made in Saijo, Ehime Prefecture, Shikoku Island, Japan, by using seepage meters for point scale, 222Rn tracer for point and coastal scales, and a numerical groundwater model (SEAWAT for coastal and basin scales. Daily basis temporal changes in SGD are evaluated by continuous seepage meter and 222Rn mooring measurements, and depend on sea level changes. Spatial evaluations of SGD were also made by 222Rn along the coast in July 2010 and November 2011. The area with larger 222Rn concentration during both seasons agreed well with the area with larger SGD calculated by 3D groundwater numerical simulations.

  4. Solar noise storms

    CERN Document Server

    Elgaroy, E O

    2013-01-01

    Solar Noise Storms examines the properties and features of solar noise storm phenomenon. The book also presents some theories that can be used to gain a better understanding of the phenomenon. The coverage of the text includes topics that cover the features and behavior of noise storms, such as the observable features of noise storms; the relationship between noise storms and the observable features on the sun; and ordered behavior of storm bursts in the time-frequency plane. The book also covers the spectrum, polarization, and directivity of noise storms. The text will be of great use to astr

  5. Risk assessment in submarine outfall projects: the case of Portugal.

    Science.gov (United States)

    Mendonça, Ana; Losada, Miguel Ángel; Reis, Maria Teresa; Neves, Maria Graça

    2013-02-15

    Submarine outfalls need to be evaluated as part of an integrated environmental protection system for coastal areas. Although outfalls are tight with the diversity of economic activities along a densely populated coastline being effluent treatment and effluent reuse a sign of economic prosperity, precautions must be taken in the construction of these structures. They must be designed so as to have the least possible impact on the environment and at the same time be economically viable. This paper outlines the initial phases of a risk assessment procedure for submarine outfall projects. This approach includes a cost-benefit analysis in which risks are systematically minimized or eliminated. The methods used in this study also allow for randomness and uncertainty. The input for the analysis is a wide range of information and data concerning the failure probability of outfalls and the consequences of an operational stoppage or failure. As part of this risk assessment, target design levels of reliability, functionality, and operationality were defined for the outfalls. These levels were based on an inventory of risks associated with such construction projects, and thus afforded the possibility of identifying possible failure modes. This assessment procedure was then applied to four case studies in Portugal. The results obtained were the values concerning the useful life of the outfalls at the four sites and their joint probability of failure against the principal failure modes assigned to ultimate and serviceability limit states. Also defined were the minimum operationality of these outfalls, the average number of admissible technical breakdowns, and the maximum allowed duration of a stoppage mode. It was found that these values were in consonance with the nature of the effluent (tourist-related, industrial, or mixed) as well as its importance for the local economy. Even more important, this risk assessment procedure was able to measure the impact of the outfalls on

  6. Geo-hazard by sediment mass movements in submarine canyons

    Science.gov (United States)

    Ghaith, Afif; Fakhri, Milad; Ivaldi, Roberta; Ciavola, Paolo

    2017-04-01

    Submarine mass movements and their consequences are of major concern for coastal communities and infrastructures but also for the exploitation and the development of seafloor resources. Elevated awareness of the need for better understanding of the underwater mass movement is coupled with great advances in underwater mapping technologies over the past two decades. The seafloor in the Nahr Ibrahim and Saida regions (Lebanon) is characterized by deep canyons, reaching one thousand meters depths in proximity of the coast. Signs of submarine mass movement instability related to these canyons create a connection between shallow and deep water. The presence of these canyons in a tectonically active area generates a particular drained mechanism to the sediment in form of mass movement and slumping. Identification of potential areas where slope movements could be triggered requires data with high spatial resolution. Since this area is poorly explored, in the framework of an international project between Lebanese Navy, Lebanese National Center for Marine Sciences, University of Ferrara and Italian Hydrographic Institute, we analyse the morpho-bathymetric and sedimentological characters of the coastal and shelf sectors. Multibeam echosounder and sub-bottom profiler acoustic systems calibrated with ground truths (sediment grab and core samples) allow us to characterize the nature of seafloor and sub-seafloor with particular detail to the geotechnical properties of sediments and high resolution seismic stratigraphy of the shallow layers. The detection of particular undersea features provides detail maps which are in support to littoral morpho-dynamics, coastal transport and sediment budget. Multilayer hydro-oceanographic map, referring to the seafloor dynamics in connection with deep water environment and drainage system, in accordance to the International Hydrographic Standards and nautical supports, are produced. This high resolution multibeam bathymetry dataset, integrated

  7. Did a "lucky shot" sink the submarine H.L. Hunley?

    Science.gov (United States)

    Lance, Rachel M; Warder, Henry; Bass, Cameron R Dale

    2017-01-01

    The H.L. Hunley was the first submarine to be successful in combat, sinking the Union vessel Housatonic outside Charleston Harbor in 1864 during the Civil War. However, despite marking a milestone in military history, little is known about this vessel or why it sank. One popular theory is the "lucky shot" theory: the hypothesis that small arms fire from the crew of the Housatonic may have sufficiently damaged the submarine to sink it. However, ballistic experiments with cast iron samples, analysis of historical experiments firing Civil War-era projectiles at cast iron samples, and calculation of the tidal currents and sinking trajectory of the submarine indicate that this theory is not likely. Based on our results, the "lucky shot" theory does not explain the sinking of the world's first successful combat submarine. Published by Elsevier B.V.

  8. The impact of glacier geometry on meltwater plume structure and submarine melt in Greenland fjords

    NARCIS (Netherlands)

    Carroll, D.; Sutherland, D. A.; Hudson, B.; Moon, T.; Catania, G. A.; Shroyer, E. L.; Nash, J. D.; Bartholomaus, T. C.; Felikson, D.; Stearns, L. A.; Noël, B. P Y; van den Broeke, M. R.

    2016-01-01

    Meltwater from the Greenland Ice Sheet often drains subglacially into fjords, driving upwelling plumes at glacier termini. Ocean models and observations of submarine termini suggest that plumes enhance melt and undercutting, leading to calving and potential glacier destabilization. Here we

  9. An Analysis of the Effectiveness of a New Watchstanding Schedule for U.S. Submariners

    National Research Council Canada - National Science Library

    Osborn, Christopher

    2004-01-01

    A need exists within the U.S. submarine force to employ an operational schedule that provides more sleep and that is in better alignment with human circadian rhythms, thus improving cognitive effectiveness...

  10. Fuel cell systems for submarines: from the first idea to serial production

    Science.gov (United States)

    Psoma, Angela; Sattler, Gunter

    The future submarines of Howaldtswerke-Deutsche Werft AG (HDW) will be equipped with fuel cell power plants for air independent propulsion. In the 1970s the decision for a fuel cell system on submarines was made. Tests in the 1980s confirmed the feasibility of fuel cells on submarines. Positive development results in the 1990s led to series production of fuel cell equipped submarines, which will be in operation from 2003 onwards. Strictly controlled development work was necessary to reach the goal of series production. The train of thought behind this process of development is described in this paper starting with the initial idea and ending with the description of the serial production of the fuel cell power plant. The future outlook gives an impression of current development work.

  11. The risk of hydrogen explosion in a submarine p. IV The implementation of high risk projects

    Directory of Open Access Journals (Sweden)

    Kłos Ryszard

    2017-06-01

    Full Text Available This series of articles on high risk projects looks at the example of the modernisation of hydrogen incinerators on a submarine. The article describes problems connected with the management of such a project.

  12. Volume transport data from a submarine cable in the Florida Strait in 2014 (NODC Accession 0125429)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Daily mean and raw voltage volume transport data of the Florida Current collected with a submarine cable spanning from South Florida to the Grand Bahama Island in...

  13. A Statistical Analysis of the Impact of Marital Status on Nuclear Submarine Officer Retention

    National Research Council Canada - National Science Library

    Phelps, Matthew

    2001-01-01

    This thesis develops multivariate logit models to estimate the impact of marital status and the independent effect of dependent children on nuclear submarine officer retention beyond the minimum service requirement (MSR...

  14. Observations of nearshore groundwater discharge: Kahekili Beach Park submarine springs, Maui, Hawaii

    Directory of Open Access Journals (Sweden)

    P.W. Swarzenski

    2017-06-01

    New hydrological insights for the region: Estimates of submarine groundwater discharge were derived for a primary vent site and surrounding coastal waters off west Maui, Hawaii using an excess 222Rn (t1/2 = 3.8 d mass balance model. Such estimates were complemented with a novel thoron (220Rn, t1/2 = 56 s groundwater discharge tracer application, as well as oceanographic time series and thermal infrared imagery analyses. In combination, this suite of techniques provides new insight into the connectivity of the coastal aquifer with the near-shore ocean and examines the physical drivers of submarine groundwater discharge. Lastly, submarine groundwater discharge derived constituent concentrations were tabulated and compared to surrounding seawater concentrations. Such work has implications for the management of coastal aquifers and downstream nearshore ecosystems that respond to sustained constituent loadings via this submarine route.

  15. Dance With the One That Brought You: Revitalizing Antisubmarine Warfare to Counter Chinese Diesel Submarines

    National Research Council Canada - National Science Library

    Farrell, Richard

    2003-01-01

    .... Navy needs to revitalize ASW, or risk losing the ability to gain sea control in strategic areas of the East Asian Littoral and South China Sea due to a rising Chinese diesel-electric submarine threat...

  16. Submarine Upward Looking Sonar Ice Draft Profile Data and Statistics, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of upward looking sonar sea ice draft data collected by submarines in the Arctic Ocean. It includes data from both U.S. Navy and Royal Navy...

  17. Navy Trident Submarine Conversion (SSGN) Program: Background and Issues for Congress

    National Research Council Canada - National Science Library

    O'Rourke, Ronald

    2005-01-01

    ...) into cruisemissile- carrying and special operations forces (SOF) support submarines (SSGNs). The total estimated cost of the program, which has been increasing over time, is now $4,018 million...

  18. Multi-core Fibers in Submarine Networks for High-Capacity Undersea Transmission Systems

    DEFF Research Database (Denmark)

    Nooruzzaman, Md; Morioka, Toshio

    2017-01-01

    Application of multi-core fibers in undersea networks for high-capacity submarine transmission systems is studied. It is demonstrated how different architectures of submerged branching unit affect network component counts in long-haul undersea transmission systems......Application of multi-core fibers in undersea networks for high-capacity submarine transmission systems is studied. It is demonstrated how different architectures of submerged branching unit affect network component counts in long-haul undersea transmission systems...

  19. They Have Not Yet Begun to Fight: Women in the United States Navy Submarine Fleet

    Science.gov (United States)

    2016-03-11

    Navy Nurse Corps in 1908. The Nurse Corps was highly educated for the time and maintained high professional standards.3 Regardless, the struggle to...nation’s navies who integrated women into their submarine fleets ahead of the U.S. Navy. Norway, Sweden , Australian, and Great Britain all...Nations such as Norway and Sweden have been incorporating females into their submarines since the mid-1980s. 39 Sweden has had female sailors

  20. The Close Aboard Bastion: a Soviet ballistic missile submarine deployment strategy

    OpenAIRE

    Kreitler, Walter M

    1988-01-01

    Approved for public release; distribution is unlimited This thesis describes and analyzes a possible deployment posture for the Soviet ballistic missile submarine force. It examines the proposition that the Soviet Navy will establish a point defense, labeled "Close Aboard Bastions" (CABs), for its ballistic missile submarine fleet within the Soviet claimed 12 nautical mile territorial sea. This is a logical derivation of the currently widely held view that the Soviets will estab...

  1. Noise and Hearing Protection

    Science.gov (United States)

    ... often becomes permanent. Some people react to loud noise with anxiety and irritability, an increase in pulse rate and blood pressure, or an increase in stomach acid. Very loud noise can reduce efficiency in performing difficult tasks by ...

  2. Worst case meteorological scenario for Norway in case of hypothetical accident related to recovery of the Russian submarine K-27

    Energy Technology Data Exchange (ETDEWEB)

    Bartnicki, J.; Klein, H. [Norwegian Meteorological Institute, Oslo (Norway); Centre for Environmental Radioactivity, Aas (Norway); Amundsen, I.; Hosseini, A. [Norwegian Radiation Protection Authority, Oesteraas (Norway); Centre for Environmental Radioactivity, Aas (Norway); Haakenstad, H. [Norwegian Meteorological Institute, Oslo (Norway); Lind, O.C.; Salbu, B. [Norwegian University of Life Sciences, Aas (Norway); Centre for Environmental Radioactivity, Aas (Norway)

    2014-07-01

    This study is a part of a comprehensive Norwegian project led by Norwegian Radiation Protection Authority assessing risks related to a potential salvaging and decommissioning of the Russian nuclear submarine, K-27. In September 1981, the K-27 submarine was scuttled at shallow waters in the outer part of Stepovogo Bay, situated at the north-eastern coast of Novaya Zemlya. One of the scenarios that are included in the assessment is the lifting of the submarine to the surface and the subsequent transport to the Murmansk area for decommissioning. Thus, the risk of a criticality accident as a consequence of lifting and transport event cannot be ignored. A hypothetical accident might pose a serious threat to Norwegian territories and has to be considered from different perspectives. Here, we focus on the worst case meteorological scenario for Norway, but the same approach can be applied for other Scandinavian countries and Russia. As a first step, a large database with meteorological data has been prepared for the period of thirty years (1980-2010). These meteorological data are available in the 1000 km x 1000 km domain which includes both the entire Norwegian territory and the region of Novaya Zemlya. The spatial resolution of the meteorological data is 11 km and temporal 3 hours. The vertical structure includes 40 layers. The most important meteorological elements are the 3-D velocity field, the surface precipitation field and the 3-D temperature field. The second step is the development of the source terms for potential accidents which can be used by the dispersion model SNAP (Severe Nuclear Accident Program). Three locations for potential accidents with subsequent releases of radioactivity to the environment are assumed: 1) at the present location of K-27, 2) transport on the route to Murmansk and 3) in the Murmansk region. In the third step, the SNAP model will be run with meteorological data starting every 6. hour of each day during the 30 years period. As a result

  3. Noise Gating Solar Images

    Science.gov (United States)

    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

  4. Noise in mesoscopic physics

    OpenAIRE

    Martin, Thierry

    2005-01-01

    This is a course on noise which covers some of the scattering theory for normal metals, Hanbury Brown and Twiss analogs for noise correlations with electrons, noise correlations in superconducting/normal metal junctions. Entanglement in such NS systems is described with a criterion for violating Bell inegalities. The last section is devoted to the perturbative derivation of noise in a particular one dimensional correlated electron system (Luttinger liquid): edge states in the fractional quant...

  5. Submarine channel evolution linked to rising salt domes, Gulf of Mexico, USA

    Science.gov (United States)

    Carter, Rachel C.; Gani, M. Royhan; Roesler, Toby; Sarwar, Abu K. M.

    2016-08-01

    An examination of halokinetics and channel evolution together in a deepwater system provides an opportunity to investigate how submarine channel morphology is locally affected by rising salt domes. The study area is located in the northern Gulf of Mexico (GOM), directly off the Louisiana continental slope in a prominent salt dome region. The influence of salt growth on submarine channel evolution is relatively understudied, particularly in the GOM. Utilizing high-resolution 3D seismic and well data and seismic geomorphology techniques, a long-lived (~ 3 Myr) Plio-Pleistocene submarine channel system has been investigated to show a relationship between variable phases of salt motion and planform morphology of preserved submarine channels. Our data suggest that local salt motion acts as a driver for submarine channel evolution. During the late Pliocene, when salt moved upward at a relatively fast rate, channels show distinct entrenchment with narrow channel belts and overall less sinuosity. When salt motion slowed down at the beginning of the Pleistocene, channels aggraded rapidly with preserved levees, and moved toward an equilibrium state with the expansion of channel belt widths. As our results indicate, the rate of salt diapirism exerted a first-order control on channel location and morphology and distribution of reservoir-prone units. This study cautions against readily invoking allogenic factors (e.g., sea level and climate) in explaining changes in submarine channel behavior and associated fan sedimentation, particularly in regions with salt tectonics.

  6. Observations of nearshore groundwater discharge: Kahekili Beach Park submarine springs, Maui, Hawaii

    Science.gov (United States)

    Swarzenski, Peter W.; Dulai, H.; Kroeger, K.D.; Smith, C.G.; Dimova, N.; Storlazzi, C. D.; Prouty, N.G.; Gingerich, S.B.; Glenn, C. R.

    2016-01-01

    Study regionThe study region encompasses the nearshore, coastal waters off west Maui, Hawaii. Here abundant groundwater—that carries with it a strong land-based fingerprint—discharges into the coastal waters and over a coral reef.Study focusCoastal groundwater discharge is a ubiquitous hydrologic feature that has been shown to impact nearshore ecosystems and material budgets. A unique combined geochemical tracer and oceanographic time-series study addressed rates and oceanic forcings of submarine groundwater discharge at a submarine spring site off west Maui, Hawaii.New hydrological insights for the regionEstimates of submarine groundwater discharge were derived for a primary vent site and surrounding coastal waters off west Maui, Hawaii using an excess 222Rn (t1/2 = 3.8 d) mass balance model. Such estimates were complemented with a novel thoron (220Rn,t1/2 = 56 s) groundwater discharge tracer application, as well as oceanographic time series and thermal infrared imagery analyses. In combination, this suite of techniques provides new insight into the connectivity of the coastal aquifer with the near-shore ocean and examines the physical drivers of submarine groundwater discharge. Lastly, submarine groundwater discharge derived constituent concentrations were tabulated and compared to surrounding seawater concentrations. Such work has implications for the management of coastal aquifers and downstream nearshore ecosystems that respond to sustained constituent loadings via this submarine route.

  7. Additive noise properties of active matrix flat-panel imagers.

    Science.gov (United States)

    Maolinbay, M; El-Mohri, Y; Antonuk, L E; Jee, K W; Nassif, S; Rong, X; Zhao, Q

    2000-08-01

    A detailed theoretical and empirical investigation of additive noise for indirect detection, active matrix flat-panel imagers (AMFPIs) has been performed. Such imagers comprise a pixelated array, incorporating photodiodes and thin-film transistors (TFTs), and an associated electronic acquisition system. A theoretical model of additive noise, defined as the noise of an imaging system in the absence of radiation, has been developed. This model is based upon an equivalent-noise-circuit representation of an AMFPI. The model contains a number of uncorrelated noise components which have been designated as pixel noise, data line thermal noise, externally coupled noise, preamplifier noise and digitization noise. Pixel noise is further divided into the following components: TFT thermal noise, shot and 1/f noise associated with the TFT and photodiode leakage currents, and TFT transient noise. Measurements of various additive noise components were carried out on a prototype imaging system based on a 508 microm pitch, 26 x 26 cm2 array. Other measurements were performed in the absence of the array, involving discrete components connected to the preamplifier input. Overall, model predictions of total additive noise as well as of pixel, preamplifier, and data line thermal noise components were in agreement with results of their measured counterparts. For the imaging system examined, the model predicts that pixel noise is dominated by shot and 1/f noise components of the photodiode and TFT at frame times above approximately 1 s. As frame time decreases, pixel noise is increasingly dominated by TFT thermal noise. Under these conditions, the reasonable degree of agreement observed between measurements and model predictions provides strong evidence that the role of TFT thermal noise has been properly incorporated into the model. Finally, the role of the resistance and capacitance of array data lines in the model was investigated using discrete component circuits at the preamplifier

  8. The acoustic response of submarine volcanoes in the Tofua Arc and northern Lau Basin following two great earthquakes in Samoa and Chile

    Science.gov (United States)

    Bohnenstiehl, D. R.; Dziak, R. P.; Matsumoto, H.; Conder, J. A.

    2013-12-01

    Using a correlation-based detector operating on data from a short-baseline hydrophone array, persistent volcano-acoustic sources are identified within the ambient noise field of the Lau Basin during the period between January 2009 and April 2010. The submarine volcano West Mata and adjacent volcanic terrains, including the northern Matas and Volcano O, are the most active acoustic sources during the 15-month period of observation. Other areas of long-term activity include the Niua hydrothermal field, the volcanic islands of Hunga-Ha'apai, Founalei, Niuatoputapu and Niuafo'ou, two unnamed seamounts located along the southern Tofua Arc, and at least three unknown sites within the northern Lau Basin. Following the great Samoan earthquake on 29 September of 2009, seven of the volcano-acoustic sources identified exhibit increases in the rate of acoustic detection. These changes persist over time scales of days-to-months and are observed up to 900 km from the earthquake hypocenter. At least one of the volcano-acoustic sources that did not respond to the 2009 Samoan earthquake exhibits an increase in detection rate following the great Mw 8.8 Chile earthquake that occurred at a distance of ~9,500 km on 27 February 2010. These observations suggest that great earthquakes may have undocumented impacts on Earth's vast submarine volcanic systems, potentially increasing the short-term flux of magma and volcanic gas into the overlying ocean.

  9. Active noise control in a duct to cancel broadband noise

    Science.gov (United States)

    Chen, Kuan-Chun; Chang, Cheng-Yuan; Kuo, Sen M.

    2017-09-01

    The paper presents cancelling duct noises by using the active noise control (ANC) techniques. We use the single channel feed forward algorithm with feedback neutralization to realize ANC. Several kinds of ducts noises including tonal noises, sweep tonal signals, and white noise had investigated. Experimental results show that the proposed ANC system can cancel these noises in a PVC duct very well. The noise reduction of white noise can be up to 20 dB.

  10. Classical noise, quantum noise and secure communication

    Science.gov (United States)

    Tannous, C.; Langlois, J.

    2016-01-01

    Secure communication based on message encryption might be performed by combining the message with controlled noise (called pseudo-noise) as performed in spread-spectrum communication used presently in Wi-Fi and smartphone telecommunication systems. Quantum communication based on entanglement is another route for securing communications as demonstrated by several important experiments described in this work. The central role played by the photon in unifying the description of classical and quantum noise as major ingredients of secure communication systems is highlighted and described on the basis of the classical and quantum fluctuation dissipation theorems.

  11. Direct-reading dial for noise temperature and noise resistance

    DEFF Research Database (Denmark)

    Diamond, J.M.

    1967-01-01

    An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance.......An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance....

  12. Experimental modeling of gravity underflow in submarine channels

    Science.gov (United States)

    Islam, Mohammad Ashraful

    Active and relic meandering channels are common on the seafloor adjacent to continental margins. These channels and their associated submarine fan deposits are products of the density-driven gravity flows known as turbidity currents. Unlike natural rivers, few attempts have been made to explore the process of channel meandering in the submarine environment. This research focuses on resolving the flow field of submarine channels by conducting experiments in a large laboratory basin. Saline and particulate density flows were studied in a straight channel, a single bend sinuous channel with vertical sidewalls and a multiple-bend sinuous channel with sloping sidewalls. Instantaneous velocities in steady developed currents were measured using 3-component acoustic Doppler velocity probes. Excess fractional density was measured at selected locations by collecting water sample using a siphon rake. Turbulent kinetic energy and Reynolds stress components are derived from the instantaneous velocity data of the straight channel experiments. Structure functions for mean velocity, Reynolds stress and turbulent kinetic energy profiles are derived by fitting normalized data. The normalized Reynolds-averaged velocity shows excellent similarity collapse while the Reynolds-stress and the turbulent kinetic energy profiles display reasonable similarity. Vertical profiles of the turbulent kinetic energy display two peaks separated by a zone of low turbulence; the ratio of the maximum to the depth-averaged turbulent kinetic energy is approximately 1.5. Theoretical profile of turbulent kinetic energy is derived. Comparisons of experimentally and theoretically derived turbulent kinetic energy profiles show reasonable agreement except at the position of velocity maximum where the theoretical profile displays a very small value. Velocity profiles derived from the measurements with confined flow in the single bend channel reveal that channel curvature drives two helical flow cells, one

  13. Long-term flow monitoring of submarine gas emanations

    Science.gov (United States)

    Spickenbom, K.; Faber, E.; Poggenburg, J.; Seeger, C.

    2009-04-01

    One of the Carbon Capture and Storage (CCS) strategies currently under study is the sequestration of CO2 in sub-seabed geological formations. Even after a thorough review of the geological setting, there is the possibility of leaks from the reservoirs. As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop innovative research and technologies for monitoring and verification of carbon dioxide geological storage, we are working on the development of submarine long-term gas flow monitoring systems. Technically, however, these systems are not limited to CO2 but can be used for monitoring of any free gas emission (bubbles) on the seafloor. The basic design of the gas flow sensor system was derived from former prototypes developed for monitoring CO2 and CH4 on mud volcanoes in Azerbaijan. This design was composed of a raft floating on the surface above the gas vent to collect the bubbles. Sensors for CO2 flux and concentration and electronics for data storage and transmission were mounted on the raft, together with battery-buffered solar panels for power supply. The system was modified for installation in open sea by using a buoy instead of a raft and a funnel on the seafloor to collect the gas, which is then guided above water level through a flexible tube. Besides some technical problems (condensed water in the tube, movement of the buoys due to waves leading to biased measurement of flow rates), this setup provides a cost-effective solution for shallow waters. However, a buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. These requirements can best be complied by a completely submersed system. To allow unattended long-term monitoring in a submarine environment, such a system has to be extremely durable. Therefore, we focussed on developing a mechanically and electrically as simple setup as possible, which has the additional advantage of low cost. The system

  14. Using Google Earth for Submarine Operations at Pavilion Lake

    Science.gov (United States)

    Deans, M. C.; Lees, D. S.; Fong, T.; Lim, D. S.

    2009-12-01

    During the July 2009 Pavilion Lake field test, we supported submarine "flight" operations using Google Earth. The Intelligent Robotics Group at NASA Ames has experience with ground data systems for NASA missions, earth analog field tests, disaster response, and the Gigapan camera system. Leveraging this expertise and existing software, we put together a set of tools to support sub tracking and mapping, called the "Surface Data System." This system supports flight planning, real time flight operations, and post-flight analysis. For planning, we make overlays of the regional bedrock geology, sonar bathymetry, and sonar backscatter maps that show geology, depth, and structure of the bottom. Placemarks show the mooring locations for start and end points. Flight plans are shown as polylines with icons for waypoints. Flight tracks and imagery from previous field seasons are embedded in the map for planning follow-on activities. These data provide context for flight planning. During flights, sub position is updated every 5 seconds from the nav computer on the chase boat. We periodically update tracking KML files and refresh them with network links. A sub icon shows current location of the sub. A compass rose shows bearings to indicate heading to the next waypoint. A "Science Stenographer" listens on the voice loop and transcribes significant observations in real time. Observations called up to the surface immediately appear on the map as icons with date, time, position, and what was said. After each flight, the science back room immediately has the flight track and georeferenced notes from the pilots. We add additional information in post-processing. The submarines record video continuously, with "event" timestamps marked by the pilot. We cross-correlate the event timestamps with position logs to geolocate events and put a preview image and compressed video clip into the map. Animated flight tracks are also generated, showing timestamped position and providing timelapse

  15. Did a submarine landslide contribute to the 2011 Tohoku tsunami?

    KAUST Repository

    Tappin, David R.

    2014-09-28

    Many studies have modeled the Tohoku tsunami of March 11, 2011 as being due entirely to slip on an earthquake fault, but the following discrepancies suggest that further research is warranted. (1) Published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40 m measured along the coast of the Sanriku district in the northeast part of Honshu Island. (2) Published models cannot reproduce the timing and high-frequency content of tsunami waves recorded at three nearshore buoys off Sanriku, nor the timing and dispersion properties of the waveforms at offshore DART buoy #21418. (3) The rupture centroids obtained by tsunami inversions are biased about 60 km NNE of that obtained by the Global CMT Project. Based on an analysis of seismic and geodetic data, together with recorded tsunami waveforms, we propose that, while the primary source of the tsunami was the vertical displacement of the seafloor due to the earthquake, an additional tsunami source is also required. We infer the location of the proposed additional source based on an analysis of the travel times of higher-frequency tsunami waves observed at nearshore buoys. We further propose that the most likely additional tsunami source was a submarine mass failure (SMF—i.e., a submarine landslide). A comparison of pre- and post-tsunami bathymetric surveys reveals tens of meters of vertical seafloor movement at the proposed SMF location, and a slope stability analysis confirms that the horizontal acceleration from the earthquake was sufficient to trigger an SMF. Forward modeling of the tsunami generated by a combination of the earthquake and the SMF reproduces the recorded on-, near- and offshore tsunami observations well, particularly the high-frequency component of the tsunami waves off Sanriku, which were not well simulated by previous models. The conclusion that a significant part of the 2011 Tohoku tsunami was generated by an SMF source has important implications for

  16. Numerical computation of tyre radiaion noise: a comparative study of different techniques

    NARCIS (Netherlands)

    Karthik, B.; Makwana, B.K.; Patel, C.; Bekke, Dirk

    2012-01-01

    Increasingly stringent noise regulations concerning automotive vehicles particularly in Europe are forcing Tyre manufacturers as well as the automotive manufacturers to reduce radiated noise. With the future moving towards electric/hybrid vehicles, the ever present tyre noise will become more

  17. Noise from wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Fegeant, Olivier [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Building Sciences

    2002-02-01

    A rapid growth of installed wind power capacity is expected in the next few years. However, the siting of wind turbines on a large scale raises concerns about their environmental impact, notably with respect to noise. To this end, variable speed wind turbines offer a promising solution for applications in densely populated areas like the European countries, as this design would enable an efficient utilisation of the masking effect due to ambient noise. In rural and recreational areas where wind turbines are sited, the ambient noise originates from the action of wind on the vegetation and about the listener's ear (pseudo-noise). It shows a wind speed dependence similar to that of the noise from a variable speed wind turbine and can therefore mask the latter for a wide range of conditions. However, a problem inherent to the design of these machines is their proclivity to pure tone generation, because of the enhanced difficulty of avoiding structural resonances in the mechanical parts. Pure tones are deemed highly annoying and are severely regulated by most noise policies. In relation to this problem, the vibration transmission of structure-borne sound to the tower of the turbine is investigated, in particular when the tower is stiffened at its upper end. Furthermore, since noise annoyance due to wind turbine is mostly a masking issue, the wind-related sources of ambient noise are studied and their masking potentials assessed. With this aim, prediction models for wind-induced vegetation noise and pseudo-noise have been developed. Finally, closely related to the effect of masking, is the difficulty, regularly encountered by local authorities and wind farm developers, to measure noise immission from wind turbines. A new measurement technique has thus been developed in the course of this work. Through improving the signal-to-noise ratio between wind turbine noise and ambient noise, the new technique yields more accurate measurement results.

  18. Raman amplification in an optically high-powered data link dedicated to a 10 km long extension for submarine cabled observatories

    Science.gov (United States)

    Audo, F.; Perhirin, S.; Quintard, V.; Guegan, M.; Perennou, A.; Auffret, Y.

    2013-05-01

    We describe a quasi-all-optical extension dedicated to simplifying the deployment of submarine cabled observatories. Based on power-over-fiber technologies, high power supply and data are both transmitted in one optical fiber of a few kilometers in length. We study the Raman amplification on the down- and up-stream data in the static regime with the high optical power varying from 100 mW to 4 W over a 10 km long single-mode optical fiber. We focus on the data optical budget and signal to noise ratio dependence with respect to the high optical power value and the data optical wavelength. We also present the transmission quality in the dynamic regime of this quasi-all-optical extension.

  19. Natural and man-made terrestrial electromagnetic noise: an outlook

    Directory of Open Access Journals (Sweden)

    A. Meloni

    2007-06-01

    Full Text Available The terrestrial environment is continuously exposed to electromagnetic radiations which set up a «background» electromagnetic noise. Within the Non Ionizing Radiation band (NIR, i.e. for frequencies lower than 300 GHz, this background can have a natural or an artificial origin. Natural origins of electromagnetic radiations are generally atmospheric or cosmic while artificial origins are technological applications, power transmission, communications, etc. This paper briefly describes the natural and man-made electromagnetic noise in the NIR band. Natural noise comes from a large variety of sources involving different physical phenomena and covering a wide range of frequencies and showing various propagation characteristics with an extremely broad range of power levels. Due to technological growth man-made electromagnetic noise is nowadays superimposed on natural noise almost everywhere on Earth. In the last decades man-made noise has increased dramatically over and above the natural noise in residential and business areas. This increase has led some scientists to consider possible negative effects of electromagnetic waves on human life and living systems in general. Accurate measurements of natural and man-made electromagnetic noise are necessary to understand the relative power levels in the different bands and their influence on life.

  20. Modeling Noise Sources and Propagation in External Gear Pumps

    Directory of Open Access Journals (Sweden)

    Sangbeom Woo

    2017-07-01

    Full Text Available As a key component in power transfer, positive displacement machines often represent the major source of noise in hydraulic systems. Thus, investigation into the sources of noise and discovering strategies to reduce noise is a key part of improving the performance of current hydraulic systems, as well as applying fluid power systems to a wider range of applications. The present work aims at developing modeling techniques on the topic of noise generation caused by external gear pumps for high pressure applications, which can be useful and effective in investigating the interaction between noise sources and radiated noise and establishing the design guide for a quiet pump. In particular, this study classifies the internal noise sources into four types of effective load functions and, in the proposed model, these load functions are applied to the corresponding areas of the pump case in a realistic way. Vibration and sound radiation can then be predicted using a combined finite element and boundary element vibro-acoustic model. The radiated sound power and sound pressure for the different operating conditions are presented as the main outcomes of the acoustic model. The noise prediction was validated through comparison with the experimentally measured sound power levels.

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

    Science.gov (United States)

    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 noise was significantly lower (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.

  2. On autocorrelation analysis of jet noise.

    Science.gov (United States)

    Harker, Blaine M; Gee, Kent L; Neilsen, Tracianne B; Wall, Alan T; McInerny, Sally A; James, Michael M

    2013-06-01

    Meaningful use of the autocorrelation in jet noise analysis is examined. The effect of peak frequency on the autocorrelation function width is removed through a temporal scaling prior to making comparisons between measurements or drawing conclusions about source characteristics. In addition, a Hilbert transform-based autocorrelation envelope helps to define consistent characteristic time scales. Application of these processes to correlation functions based on large and fine-scale similarity spectra reveal that the large-scale noise radiation from an F-22A deviates from the similarity spectrum model.

  3. Submarine pyroclastic deposits in Tertiary basins, NE Slovenia

    Directory of Open Access Journals (Sweden)

    Polona Kralj

    2013-12-01

    Full Text Available In Tertiary basins of NE Slovenia, Upper Oligocene volcanic activity occurred in a submarine environment that experienced contemporaneous clastic sedimentation. Pyroclastic deposits are essentially related to gas- and watersupported eruption-fed density currents. At Trobni Dol, the Lako Basin, an over 100 m thick deposit formed by a sigle sustained volcanic explosion that fed gas-supported pyroclastic flow. Diagnostic features are large matrixshard content, normal grading of pumice lapilli, collapsed pumice lapilli and the presence of charcoal. In the Smrekovec Volcanic Complex, several but only up to 5 m thick deposits related to eruption-fed gassupported pyroclastic flows occur. Deposits settled from water-supported eruption-fed density currents form fining- and thinning-upward sedimentary units which resemble the units of volcaniclastic turbidites. Pyroclastic deposits related to gas- and water-supported density currents occur in an up to 1000 m thick succession composed of coherent volcanics, autoclastic, pyroclastic, reworked volcaniclastic and mixed volcaniclastic-siliciclastic deposits that indicate a complex explosive and depositional history of the Smrekovec Volcanic Complex.

  4. Breathing modes of Kolumbo submarine volcano (Santorini, Greece).

    Science.gov (United States)

    Bakalis, Evangelos; Mertzimekis, Theo J; Nomikou, Paraskevi; Zerbetto, Francesco

    2017-04-13

    Submarine volcanoes, such as Kolumbo (Santorini, Greece) are natural laboratories for fostering multidisciplinary studies. Their investigation requires the most innovative marine technology together with advanced data analysis. Conductivity and temperature of seawater were recorded directly above Kolumbo's hydrothermal vent system. The respective time series have been analyzed in terms of non-equilibrium techniques. The energy dissipation of the volcanic activity is monitored by the temperature variations of seawater. The venting dynamics of chemical products is monitored by water conductivity. The analysis of the time series in terms of stochastic processes delivers scaling exponents with turning points between consecutive regimes for both conductivity and temperature. Changes of conductivity are shown to behave as a universal multifractal and their variance is subdiffusive as the scaling exponents indicate. Temperature is constant over volcanic rest periods and a universal multifractal behavior describes its changes in line with a subdiffusive character otherwise. The universal multifractal description illustrates the presence of non-conservative conductivity and temperature fields showing that the system never retains a real equilibrium state. The existence of a repeated pattern of the combined effect of both seawater and volcanic activity is predicted. The findings can shed light on the dynamics of chemical products emitted from the vents and point to the presence of underlying mechanisms that govern potentially hazardous, underwater volcanic environments.

  5. High-efficiency airfoil rudders applied to submarines

    Directory of Open Access Journals (Sweden)

    ZHOU Yimei

    2017-03-01

    Full Text Available Modern submarine design puts forward higher and higher requirements for control surfaces, and this creates a requirement for designers to constantly innovate new types of rudder so as to improve the efficiency of control surfaces. Adopting the high-efficiency airfoil rudder is one of the most effective measures for improving the efficiency of control surfaces. In this paper, we put forward an optimization method for a high-efficiency airfoil rudder on the basis of a comparative analysis of the various strengths and weaknesses of the airfoil, and the numerical calculation method is adopted to analyze the influence rule of the hydrodynamic characteristics and wake field by using the high-efficiency airfoil rudder and the conventional NACA rudder comparatively; at the same time, a model load test in a towing tank was carried out, and the test results and simulation calculation obtained good consistency:the error between them was less than 10%. The experimental results show that the steerage of a high-efficiency airfoil rudder is increased by more than 40% when compared with the conventional rudder, but the total resistance is close:the error is no more than 4%. Adopting a high-efficiency airfoil rudder brings much greater lifting efficiency than the total resistance of the boat. The results show that high-efficiency airfoil rudder has obvious advantages for improving the efficiency of control, giving it good application prospects.

  6. Submarine springs and coastal karst aquifers: A review

    Science.gov (United States)

    Fleury, Perrine; Bakalowicz, Michel; de Marsily, Ghislain

    2007-06-01

    SummaryThis article reports on current knowledge of coastal karst aquifers, in which conduit flow is dominant, and its aim is to characterise the functioning of these systems which are closely linked to the sea. First, earlier and recent studies of these aquifers are discussed. On the basis of their findings, it can be shown that two essential mechanisms are involved in the functioning of these systems, i.e., aquifer discharge through submarine springs and saline intrusion through conduits open to the sea. Then, the conditions that give rise to these aquifers are described and particular emphasis is placed on the influence of deep karstification when the sea level falls. The base-level variations are attributed to the glaciations or, in the specific case of the Mediterranean, to the salinity crisis in the Messinian period. It is this inherited structure, sometimes containing very deep conduits below sea level, that today conditions the aquifer flow. The flow in the conduits open to the sea depends on the hydraulic head gradient between the aquifer and the sea and is therefore a function of the water density and head losses in the aquifer. This survey of coastal karst aquifers has revealed some common characteristics that show the development and/or functional capacity of their karstic drainage networks. A classification of such systems into three categories is proposed with the aim of assisting in the decision-making concerning potential exploitation of water resources in coastal regions.

  7. Sea-level-induced seismicity and submarine landslide occurrence

    Science.gov (United States)

    Brothers, Daniel S.; Luttrell, Karen M.; Chaytor, Jason D.

    2013-01-01

    The temporal coincidence between rapid late Pleistocene sea-level rise and large-scale slope failures is widely documented. Nevertheless, the physical mechanisms that link these phenomena are poorly understood, particularly along nonglaciated margins. Here we investigate the causal relationships between rapid sea-level rise, flexural stress loading, and increased seismicity rates along passive margins. We find that Coulomb failure stress across fault systems of passive continental margins may have increased more than 1 MPa during rapid late Pleistocene–early Holocene sea-level rise, an amount sufficient to trigger fault reactivation and rupture. These results suggest that sea-level–modulated seismicity may have contributed to a number of poorly understood but widely observed phenomena, including (1) increased frequency of large-scale submarine landslides during rapid, late Pleistocene sea-level rise; (2) emplacement of coarse-grained mass transport deposits on deep-sea fans during the early stages of marine transgression; and (3) the unroofing and release of methane gas sequestered in continental slope sediments.

  8. Ecostructuring of marine nematode communities by submarine groundwater discharge.

    Science.gov (United States)

    Grzelak, Katarzyna; Tamborski, Joseph; Kotwicki, Lech; Bokuniewicz, Henry

    2018-02-02

    Inputs of submarine groundwater discharge (SGD) to the coastal ocean may alter local and regional-scale biology. Here, we report on nematode assemblages along the north shore of Long Island, NY. We test if nematode communities differed between sites impacted by mixed fresh-saline SGD and where SGD is exclusively saline. Diversity of nematodes was low at sites impacted by fresh SGD and communities were dominated by a few opportunistic genera. Moreover, a set of typical freshwater nematode genera restricted to impacted sites was observed. Their presence in the marine coastal zone is exceptional and underlines the structuring role that fresh SGD plays in the local ecosystem. Saline SGD structured nematode assemblages differently compared to sites impacted by fresh SGD. The number of nematode genera was markedly higher at saline SGD sites, with a different community structure. This study highlights the importance to which inputs of fresh SGD may have on local ecosystem diversity in marine coastal environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Breathing modes of Kolumbo submarine volcano (Santorini, Greece)

    Science.gov (United States)

    Bakalis, Evangelos; Mertzimekis, Theo J.; Nomikou, Paraskevi; Zerbetto, Francesco

    2017-04-01

    Submarine volcanoes, such as Kolumbo (Santorini, Greece) are natural laboratories for fostering multidisciplinary studies. Their investigation requires the most innovative marine technology together with advanced data analysis. Conductivity and temperature of seawater were recorded directly above Kolumbo’s hydrothermal vent system. The respective time series have been analyzed in terms of non-equilibrium techniques. The energy dissipation of the volcanic activity is monitored by the temperature variations of seawater. The venting dynamics of chemical products is monitored by water conductivity. The analysis of the time series in terms of stochastic processes delivers scaling exponents with turning points between consecutive regimes for both conductivity and temperature. Changes of conductivity are shown to behave as a universal multifractal and their variance is subdiffusive as the scaling exponents indicate. Temperature is constant over volcanic rest periods and a universal multifractal behavior describes its changes in line with a subdiffusive character otherwise. The universal multifractal description illustrates the presence of non-conservative conductivity and temperature fields showing that the system never retains a real equilibrium state. The existence of a repeated pattern of the combined effect of both seawater and volcanic activity is predicted. The findings can shed light on the dynamics of chemical products emitted from the vents and point to the presence of underlying mechanisms that govern potentially hazardous, underwater volcanic environments.

  10. assessment of noise pollutio noise pollutio noise pollution

    African Journals Online (AJOL)

    eobe

    related ailments impairment (71.9%). Therefore noi impairment (71.9%). Therefore noise prevention se prevention audiometric tests, training, education, and enforcem. Keywords: Keywords: .... marketing for local consumption or transportation to the northern ..... disorders in workers as well as those living within the vicinity of ...

  11. Poultry Plant Noise Control

    Science.gov (United States)

    1982-01-01

    A demonstration conducted last winter at the Tip Top Poultry Plant intended to show poultry plant managers from all over the U.S. potential solutions to the problem of plant noise. Plastic covers used over sound absorbing materials need to meet cleanability requirements, high- pressure water cleaning and other harsh maintenance procedures peculiar to the poultry processing industry. For the demonstration, Fiber Flex, Inc. manufactured and donated 750 noise panels; Owens-Corning Fiberglas Corporation donated the fiberglas cores; and the cover material was purchased from Howe and Bainbridge. The Engineering Experiment Station (EES) conducted before and after noise surveys and is evaluating the effect of noise reduction on turnover and productivity in the demonstration plant. EES plans to conduct a noise abatement workshop and update a handbook to help poultry processors with noise problems. EES study and demonstration may be applicable to other food processing plants where similar sanitary constraints exist.

  12. The Enemy Below - The Global Diffusion of Submarines and Related Technology

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, K G

    2002-09-05

    The end of the Cold War seemed to create a more peaceful international environment. September 11 reminded us of the dangers of complacency. Indeed, even before September 11 US forces had intervened in a number of wars and crises, including Panama, the Persian Gulf War, Somalia, Rwanda, Bosnia, Kosovo, several Taiwan Straits crises, the North Korea nuclear weapons crisis, and most recently Afghanistan. US ability to intervene in remote areas of the world is often dependent on the Navy's ability to project power ashore. As a result, US ability to influence events in crisis situations, especially between or among nuclear powers, may become more difficult along with our ability to conduct littoral warfare. Although the numbers of potentially hostile submarines have declined with the end of the Cold War, US anti-submarine warfare capabilities have also declined. Moreover, foreign submarines and related technologies are likely to diffuse globally. New technologies like Air Independent Propulsion (AIP), improved weapons and sensors will make conventional submarines more dangerous, and the spread of nuclear submarines even to a few more countries raise political, military, environmental, and safety concerns. Submarines are one of the key weapon systems used alone or in combination with other weapon systems such as coastal defense missiles, aircraft, and other sea-based missile platforms to deny US ability to project power ashore, Thus, other countries who wish to deny the US the ability to interfere with their regional or even global ambitions may emphasize the acquisition and/or development of submarines. As the world become more multipolar over the longer term, as the Chinese believe it will, countries such as Russia, China. etc., may be able to acquire the submarine capabilities to challenge us not just regionally, but in blue waters. To the extent that our alliance relationships require US naval access or superiority to sustain them, then our erstwhile friendly

  13. Natural and man-made terrestrial electromagnetic noise: an outlook

    OpenAIRE

    Bianchi, C.; Meloni, A.

    2007-01-01

    The terrestrial environment is continuously exposed to electromagnetic radiations which set up a «background» electromagnetic noise. Within the Non Ionizing Radiation band (NIR), i.e. for frequencies lower than 300 GHz, this background can have a natural or an artificial origin. Natural origins of electromagnetic radiations are generally atmospheric or cosmic while artificial origins are technological applications, power transmission, communications, etc. This paper briefly descri...

  14. Noise at the Interface

    DEFF Research Database (Denmark)

    Prior, Andrew

    2011-01-01

    The notion of noise occupies a contested territory, in which it is framed as pollution and detritus even as it makes its opposite a possibility - noise is always defined in opposition to something else, even if this ‘other’ is not quite clear. This paper explores noise in the context of ‘the...... interface’ asking what its affordances as an idea may contribute to our understanding of interface. I draw historically on information theory in particular to initiate this exploration....

  15. Acceptable noise level

    DEFF Research Database (Denmark)

    Olsen, Steen Østergaard; Nielsen, Lars Holme; Lantz, Johannes

    2012-01-01

    The acceptable noise level (ANL) is used to quantify the amount of background noise that subjects can accept while listening to speech, and is suggested for prediction of individual hearing-aid use. The aim of this study was to assess the repeatability of the ANL measured in normal-hearing subjects...... using running Danish and non-semantic speech materials as stimuli and modulated speech-spectrum and multi-talker babble noises as competing stimuli....

  16. Westward advance of the deformation front and evolution of submarine canyons offshore of southwestern Taiwan

    Science.gov (United States)

    Han, Wei-Chung; Liu, Char-Shine; Chi, Wu-Cheng; Chen, Liwen; Lin, Che-Chuan; Chen, Song-Chuen

    2017-11-01

    This study analyzes both 2D and 3D seismic images around the Palm Ridge area offshore of southwestern Taiwan to understand how the deformation front shifted westward and how tectonic activities interact with submarine canyon paths in the transition area between the active and passive margins. Palm Ridge is a submarine ridge that developed on the passive China continental margin by down-dip erosion of several tributaries of Penghu Canyon; it extends eastward across the deformation front into the submarine Taiwan accretionary wedge. The presence of proto-thrusts that are located west of the frontal thrust implies that the compressional stress field has advanced westward due to the convergence of the Philippine Sea Plate and Eurasian Plate. Since the deformation front is defined as the location of the most frontal contractional structure, no significant contractional structure should appear west of it. We thus suggest moving the location of the previously mapped deformation front farther west to where the westernmost proto-thrust lies. High-resolution seismic and bathymetric data reveal that the directions of the paleo-submarine canyons run transverse to the present slope dip, while the present submarine canyons head down slope in the study area. We propose that this might be the result of the westward migration of the deformation front that changed the paleo-bathymetry and thus the canyon path directions. The interactions of down-slope processes and active tectonics control the canyon paths in our study area.

  17. Methane concentration inside a submarine mud volcano examined through seismic velocity profiles

    Science.gov (United States)

    Kioka, Arata; Tsuji, Takeshi; Otsuka, Hironori; Ashi, Juichiro

    2017-04-01

    Mud volcanoes are considered to be among largest geological sources releasing hydrocarbon gases into the atmosphere. Numerous studies have revealed their origins and compositions from submarine mud volcanoes. A recent long-term observation at a submarine mud volcano sheds light on that larger volume of methane gas than expected is escaped from deep-water mud volcanoes, suggesting that the global methane flux from the seafloor is likely underestimated. Yet, estimates of the gas amount inside mud volcanoes have been still challenging, because of the difficulty of in-situ measurements. This study provides a new model to bridge methane amounts and seismic velocities in fluidized mud conduits of submarine mud volcanoes. This model is universally applicable and enables estimates of methane concentration in the mud conduits, using the seismic velocity profile derived from reflection/refraction seismic and/or downhole logging data. In this study, (1) we examine our modeled results through deep-drilling data obtained at mud volcanoes in the Olimpi mud field of the central Mediterranean Ridge accretionary margin, to evaluate the difference between in situ methane amounts and those calculated from our model, and (2) apply our model to the seismic velocity profile derived from seicmic data to estimate the methane amount inside the submarine mud volcano in the Nankai accretionary margin. Our scheme may provide an opportunity to re-estimate the total methane flux from submarine mud volcanoes.

  18. Signal processing of jet noise from flyover test data

    Science.gov (United States)

    Kelly, Jeffrey J.; Wilson, Mark R.

    1993-01-01

    Narrow-band spectra characterizing jet noise are constructed from flyover acoustic measurements. Radar and c-band tracking systems provided the aircraft position histories which enabled directivity and smear angles from the aircraft to each microphone to be computed. These angles are based on source emission time and thus give some idea about the directivity of the radiated sound field due to jet noise. Simulated spectra are included in the paper to demonstrate spectral broadening due to smear angle. The acoustic data described in the study has application to community noise analysis, noise source characterization and validation of prediction models. Both broadband-shock noise and turbulent mixing noise are observed in the spectra. A detailed description of the signal processing procedures is provided.

  19. Noise upon the Sinusoids

    DEFF Research Database (Denmark)

    Jensen, Karl Kristoffer

    2005-01-01

    Sinusoids are used for making harmonic and other sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having...... control for strength and bandwidth. The noise is added on the frequency and amplitudes of the sinusoids, and the resulting irregularity’s (jitter and shimmer) bandwidth is derived. This, together with an overview of investigation methods of the jitter and shimmer results in an analysis of the necessary...

  20. Noise in biological circuits.

    Science.gov (United States)

    Simpson, Michael L; Cox, Chris D; Allen, Michael S; McCollum, James M; Dar, Roy D; Karig, David K; Cooke, John F

    2009-01-01

    Noise biology focuses on the sources, processing, and biological consequences of the inherent stochastic fluctuations in molecular transitions or interactions that control cellular behavior. These fluctuations are especially pronounced in small systems where the magnitudes of the fluctuations approach or exceed the mean value of the molecular population. Noise biology is an essential component of nanomedicine where the communication of information is across a boundary that separates small synthetic and biological systems that are bound by their size to reside in environments of large fluctuations. Here we review the fundamentals of the computational, analytical, and experimental approaches to noise biology. We review results that show that the competition between the benefits of low noise and those of low population has resulted in the evolution of genetic system architectures that produce an uneven distribution of stochasticity across the molecular components of cells and, in some cases, use noise to drive biological function. We review the exact and approximate approaches to gene circuit noise analysis and simulation, and review many of the key experimental results obtained using flow cytometry and time-lapse fluorescent microscopy. In addition, we consider the probative value of noise with a discussion of using measured noise properties to elucidate the structure and function of the underlying gene circuit. We conclude with a discussion of the frontiers of and significant future challenges for noise biology. (c) 2009 John Wiley & Sons, Inc.

  1. Landing gear noise attenuation

    Science.gov (United States)

    Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)

    2011-01-01

    A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

  2. The Dielectric Bolometer, A New Type of Thermal Radiation Detector

    Science.gov (United States)

    Hanel, R. A.

    1960-01-01

    Thermal detectors for the infrared, such as thermocouples and bolometers, are limited in their ultimate sensitivity predominantly by Johnson noise rather than temperature noise. Low noise figures are hard to achieve since Johnson noise preponderates temperature noise, which is the only essential noise for thermal detectors. The dielectric constants of some materials are sufficiently temperature dependent to make a new type of bolometer feasible. The basic theory of a dielectric bolometer, as shown here, promises noise figures below 3 decibels even at chopper frequencies well above the 1/tau value of the detector. Ferroelectrics such as barium-strontium titanate and others seem to be well suited for radiation-cooled dielectric bolometers.

  3. Noise and Health: How does noise affect us?

    NARCIS (Netherlands)

    Miedema, H.M.E.

    2001-01-01

    Noise annoyance is a primary indication that noise is a problem, and by itself noise annoyance means that the quality of life is adversely affected. Results from noise annoyance research are presented that make possible a detailed evaluation of noise exposures with respect to the annoyance induced.

  4. The Keelung Submarine Volcano in the near-shore area of northern Taiwan and its tectonic implication

    Science.gov (United States)

    Tsai, Ching-Hui; Hsu, Shu-Kun; Lin, Shiao-Shan; Yang, Tsanyao F.; Wang, Shiou-Ya; Doo, Wen-Bin; Lee, Hsiao-Fen; Lan, Tefang; Huang, Jian-Cheng; Liang, Chin-Wei

    2017-11-01

    The Taiwan mountain belt has been created due to the collision between the Philippine Sea Plate and the Eurasian Plate. Northernmost Taiwan and its offshore area are now under post-collisional collapse. The post-collisional magmatism is distributed around northern Taiwan. Here we first report a submarine volcano, named Keelung Submarine Volcano, existing in the near-shore area of northern Taiwan. The high 3He/4He ratios in the collected seawater samples suggest that the magma of the Keelung Submarine Volcano is derived from a mantle source. Geometrically, both the Keelung Submarine Volcano and the Tatun Volcano Group are situated above the western border of the subducted Philippine Sea Plate and may have a same magma source. Both volcanic areas belong to the northern Taiwan volcanic zone, instead of the Ryukyu volcanic front. The Keelung Submarine Volcano has been rotated clockwise ∼48° after its formation, which implies that the Keelung Submarine Volcano has formed before the Luzon arc collided against northern Taiwan. Consequently, the post-collisional model to explain the formation of the northern Taiwan volcanic zone is questionable. As indicated by numerous shallow earthquakes and persistent emissions of the volcanic gases out of the seafloor around the volcanic cone, the Keelung Submarine Volcano is as active as the Tatun Volcano Group. For the sake of volcanic hazard assessment, it is essential to monitor the activity of the Keelung Submarine Volcano.

  5. CFD RANS Simulations on a Generic Conventional Scale Model Submarine: Comparison between Fluent and OpenFOAM

    Science.gov (United States)

    2015-09-01

    1 – Hydrodynamics”, Defence Science and Technology Organisation Technical Report DSTO-TR-1622, 2004. UNCLASSIFIED DST-Group-TN-1449 UNCLASSIFIED...17 7. Joubert, P.N., “Some Aspects of Submarine Design Part 2– Shape of a Submarine 2026”, Defence Science and Technology Organisation Technical

  6. Marine controlled-source electromagnetic sounding on submarine massive sulphides using 2.5-D simulation

    Science.gov (United States)

    Imamura, N.; Goto, T.; Takekawa, J.; Mikada, H.

    2010-12-01

    Recently, controlled-source electromagnetic (EM) method is widely used for shallow sub-seafloor explorations. In conventional marine CSEM methods, we need to connect a survey vehicle and an EM transmitter using a long cable, and also connect the EM transmitter and towed receiver using a cable. However, in practice, we must tow cables far from seafloor because of rough topography (e.g, chimneys) around submarine massive sulphides (SMS). Therefore, it is difficult to get information about shallow sub-seafloor structure. In this paper, we propose a new controlled-source electromagnetic method using two autonomous underwater vehicles (AUVs) for the exploration of SMS. We set an EM transmitter to one AUV, and also set an EM receiver to another AUV. Using this method, it is possible to keep a low height of diving AUVs from the seafloor, so we can carry out the exploration of SMS effectively. A numerical simulation code for 2.5 dimensional (2.5-D) electromagnetic fields in the frequency domain is developed in order to estimate electromagnetic responses on possible conductivity structures. In this research, we compared the behavior of electric fields as various functions such as the distance between source and receiver, and discussed the possibility of our CSEM method to be applied for the exploration of SMS. From the simulation results, we found that it is possible to detect the electric field for about 150~200m offsets even under the contamination of noise. Among various combination of source and receivers, we also found that the anomalous amplitude rate becomes greatest, in particular around the edge of SMS, when polarizing both the source and receiver in the horizontal direction. We next considered the sensitivity of electromagnetic field to the location of SMS using two model calculations. We found that the received electric field becomes steeply weaker as setting the receiver apart from the transmitter when the source was placed near SMS. Above all numerical

  7. The Impact of Subsonic Twin Jets on Airport Noise

    Science.gov (United States)

    Bozak, Richard, F.

    2012-01-01

    Subsonic and supersonic aircraft concepts proposed through NASA s Fundamental Aeronautics Program have multiple engines mounted near one another. Engine configurations with multiple jets introduce an asymmetry to the azimuthal directivity of the jet noise. Current system noise predictions add the jet noise from each jet incoherently, therefore, twin jets are estimated by adding 3 EPNdB to the far-field noise radiated from a single jet. Twin jet effects have the ability to increase or decrease the radiated noise to different azimuthal observation locations. Experiments have shown that twin jet effects are reduced with forward flight and increasing spacings. The current experiment investigates the impact of spacing, and flight effects on airport noise for twin jets. Estimating the jet noise radiated from twin jets as that of a single jet plus 3 EPNdB may be sufficient for horizontal twin jets with an s/d of 4.4 and 5.5, where s is the center-to-center spacing and d is the jet diameter. However, up to a 3 EPNdB error could be present for jet spacings with an s/d of 2.6 and 3.2.

  8. High accuracy station moving method for total station in submarine construction

    Directory of Open Access Journals (Sweden)

    MIN Shaosong

    2017-10-01

    Full Text Available [Objectives] When we measure submarine pressure hulls using a total station, it is essential to set several stations in order to complete the measurement of the whole cabin due to the complicated measuring environment. However, there are many restrictions related to the total station itself when moving stations, and it is also difficult to ensure measuring accuracy and satisfy the requirements of submarine measurement in complicated environments.[Methods] As such, a new station moving method is presented which can automatically establish standing relationships by measuring common points at every measuring position.[Results] This method can significantly improve accuracy and efficiency.[Conclusions] The experiment shows that the results of the new station moving method can meet sub-pixel precision and satisfy submarine measurement requirements with high accuracy.

  9. Submarine landslide and tsunami hazards offshore southern Alaska: Seismic strengthening versus rapid sedimentation

    Science.gov (United States)

    Sawyer, Derek E.; Reece, Robert S.; Gulick, Sean P. S.; Lenz, Brandi L.

    2017-08-01

    The southern Alaskan offshore margin is prone to submarine landslides and tsunami hazards due to seismically active plate boundaries and extreme sedimentation rates from glacially enhanced mountain erosion. We examine the submarine landslide potential with new shear strength measurements acquired by Integrated Ocean Drilling Program Expedition 341 on the continental slope and Surveyor Fan. These data reveal lower than expected sediment strength. Contrary to other active margins where seismic strengthening enhances slope stability, the high-sedimentation margin offshore southern Alaska behaves like a passive margin from a shear strength perspective. We interpret that seismic strengthening occurs but is offset by high sedimentation rates and overpressure. This conclusion is supported by shear strength outside of the fan that follow an active margin trend. More broadly, seismically active margins with wet-based glaciers are susceptible to submarine landslide hazards because of the combination of high sedimentation rates and earthquake shaking.

  10. The Zambezi Channel: A new perspective on submarine channel evolution at low latitudes

    Science.gov (United States)

    Wiles, E.; Green, A.; Watkeys, M.; Jokat, W.

    2017-06-01

    Submarine channels are not stand-alone systems. They are long-lived systems modified by imperceptibly slow processes and rapid gravity flows, in some part controlled by hinterland dynamics. The submarine Zambezi Channel, within the Mozambique Channel, receives sediment from the Zambezi River catchment which has a dynamic tectonic and morphological history. Using recently collected multibeam bathymetry and PARASOUND data we discuss the geomorphology of the Zambezi Channel. Results show this system to be distinct in geomorphologic character when compared to other low-latitude submarine channels, sharing similarities with high-latitude systems. We propose a new, source-to-sink, hypothesis for the evolution of the Zambezi Channel, taking in to consideration hinterland tectonics, palaeo-lake development, river capture and rapid gravity flows. This hypothesis accounts for the unique present-day anatomy of the Zambezi Channel within the dynamic framework of the systems regional setting.

  11. Research on Big Data Attribute Selection Method in Submarine Optical Fiber Network Fault Diagnosis Database

    Directory of Open Access Journals (Sweden)

    Chen Ganlang

    2017-11-01

    Full Text Available At present, in the fault diagnosis database of submarine optical fiber network, the attribute selection of large data is completed by detecting the attributes of the data, the accuracy of large data attribute selection cannot be guaranteed. In this paper, a large data attribute selection method based on support vector machines (SVM for fault diagnosis database of submarine optical fiber network is proposed. Mining large data in the database of optical fiber network fault diagnosis, and calculate its attribute weight, attribute classification is completed according to attribute weight, so as to complete attribute selection of large data. Experimental results prove that ,the proposed method can improve the accuracy of large data attribute selection in fault diagnosis database of submarine optical fiber network, and has high use value.

  12. Chemical Fluxes from a Recently Erupted Submarine Volcano on the Mariana Arc

    Science.gov (United States)

    Buck, N. J.; Resing, J. A.; Lupton, J. E.; Larson, B. I.; Walker, S. L.; Baker, E. T.

    2016-12-01

    While hydrothermal circulation is paramount to the geochemical budget for a wide array of elements, relatively few flux estimates exist in the literature. To date most studies have concentrated on constraining global and vent-field scale inputs originating from ocean spreading ridges. The goal of this study is to directly measure the chemical flux from an active submarine volcano injecting hydrothermal fluids into the surface ocean. Ahyi Seamount, a submarine intraoceanic arc volcano located in the Northern Mariana Islands, has a summit depth TSM and total and dissolved Fe and Mn. Laboratory analyses found enriched concentrations of H2, 3He, CO2 and Fe, consistent with a recent eruption. Preliminary flux calculations estimate a Fe input of 16 mmol s-1. This indicates shallow submarine arc volcanoes are capable of supplying appreciable quantities of Fe into the surface ocean. Further laboratory analyses and calculations to characterize and constrain the fluxes of other chemical constituents are underway.

  13. Air blast injuries killed the crew of the submarine H.L. Hunley.

    Directory of Open Access Journals (Sweden)

    Rachel M Lance

    Full Text Available The submarine H.L. Hunley was the first submarine to sink an enemy ship during combat; however, the cause of its sinking has been a mystery for over 150 years. The Hunley set off a 61.2 kg (135 lb black powder torpedo at a distance less than 5 m (16 ft off its bow. Scaled experiments were performed that measured black powder and shock tube explosions underwater and propagation of blasts through a model ship hull. This propagation data was used in combination with archival experimental data to evaluate the risk to the crew from their own torpedo. The blast produced likely caused flexion of the ship hull to transmit the blast wave; the secondary wave transmitted inside the crew compartment was of sufficient magnitude that the calculated chances of survival were less than 16% for each crew member. The submarine drifted to its resting place after the crew died of air blast trauma within the hull.

  14. Origin of the Easter Submarine Alignment: morphology and structural lineaments

    Directory of Open Access Journals (Sweden)

    Cristián Rodrigo

    2014-10-01

    Full Text Available The Easter submarine alignment corresponds to a sequence of seamounts and oceanic islands which runs from the Ahu-Umu volcanic fields in the west to its intersection with the Nazca Ridge in the east, with a total length of about 2.900 km and a strike of N85°E. Recent bathymetric compilations that include combined satellite derived and shipboard data (Global Topography and multibeam bathymetric data (from NGDC-NOAA are interpreted both qualitatively and quantitatively by using a morphological analysis, which was comprised of the determination of bathymetric patterns, trends in lineations and structures; height measurements, computation of basal areas and volumes of seamounts, in order to establish clues on the origin of this seamount chain and to establish relationships with the regional tectonics. In the study region 514 seamounts were counted, of which 334 had a basal area less than the reference seamount (Moai. In general, the largest seamounts (>1000 m in height tend to align and to have a larger volume, with an elongation of their bases along the seamount chain. On the other hand, smaller seamounts tend to be distributed more randomly with more circular bases. As a consequence of the morphological analysis, the best possible mechanism that explains the origin of the seamount chain is the existence of a localized hotspot to the west of the Salas y Gómez Island. The corresponding plume would contribute additional magmatic material towards the East Pacific Rise through canalizations, whose secondary branches would feed intermediate volcanoes. It is possible that within the Easter Island region there would be another minor contribution through fractures in the crust, due to the crustal weakening that was produced by the Easter Fracture Zone.

  15. The Atlas of Submarine Glacial Landforms: Modern, Quaternary and Ancient

    Science.gov (United States)

    Dowdeswell, Julian A.; Canals, Miquel; Jakobsson, Martin; Todd, Brian J.; Dowdeswell, Evelyn K.; Hogan, Kelly A.

    2017-04-01

    Twenty years ago, the international marine community brought together a first Atlas of Acoustic Images of the high-latitude geo-marine environment (Davies et al. 1997). The present Atlas is a new attempt to summarize the state of knowledge of high-latitude glacier-influenced systems, focusing on HR imagery derived from multibeam swath bathymetry and novel 2D and 3D seismic reflection tools. These new-generation techniques, aided by accurate global positioning, have revolutionized the imaging of the seafloor and subseafloor over the past two decades and have now been deployed widely in polar and subpolar waters, providing vast quantities of new data. It is, therefore, timely to provide a compilation of the variety of submarine glacial and related landforms, together with their stratigraphic setting where possible, for scientific, technological, environmental and economic reasons. The glacial imprint on the modern seabed and palaeo-shelf surfaces, buried in glacial-sedimentary depocentres, can now be imaged better than ever before using the above techniques, providing novel insights into present and past environmental conditions and sedimentary architecture. The understanding of polar regions and their changing ice cover is of enhanced significance as they are both a key driver of global change and important responders to it. Finally, industry is increasingly interested on the dimensions and architecture of glacial sedimentary depocentres on present and past continental shelves because of the hydrocarbon potential of some glacial-sedimentary systems. The Atlas consists of a comprehensive series of over 180 contributions that describe, illustrate and discuss the full variability of landforms found on the high-latitude, glacier-influenced systems, and is organised in terms of their positions on a continental margin into those from: (1) fjords, (2) continental shelves and plateaus, and (3) the deep margin and basins beyond. The Atlas has been published by the Geological

  16. Potential Impact of Submarine Power Cables on Crab Harvest

    Science.gov (United States)

    Bull, A. S.; Nishimoto, M.

    2016-02-01

    Offshore renewable energy installations convert wave or wind energy to electricity and transfer the power to shore through transmission cables laid on or buried beneath the seafloor. West coast commercial fishermen, who harvest the highly prized Dungeness crab (Metacarcinus magister) and the rock crab (Cancer spp.), are concerned that the interface of crabs and electromagnetic fields (EMF) from these cables will present an electrified fence on the seafloor that their target resource will not cross. Combined with the assistance of professional fishermen, submarine transmission cables that electrify island communities and offshore oil platforms in the eastern Pacific provide an opportunity to test the harvest of crab species across power transmission cables. In situ field techniques give commercial crab species a choice to decide if they will cross fully energized, EMF emitting, power transmission cables, in response to baited traps. Each independent trial is either one of two possible responses: the crab crosses the cable to enter a trap (1) or the crab does not cross the cable to enter a trap (0). Conditions vary among sample units by the following categorical, fixed factors (i.e., covariates) of cable structure (buried or unburied); direction of cable from crab position (west or east, north or south); time and season. A generalized linear model is fit to the data to determine whether any of these factors affect the probability of crabs crossing an energized cable to enter baited traps. Additionally, the experimental design, aside from the number of runs (set of sample trials) and the dates of the runs, is the same in the Santa Barbara Channel for rock crab and Puget Sound for Dungeness crab, and allows us to compare the capture rates of the two species in the two areas. We present preliminary results from field testing in 2015.

  17. Anatomy of La Jolla submarine canyon system; offshore southern California

    Science.gov (United States)

    Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

    2013-01-01

    An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (< 10 cm) turbidites, they are inferred to be part of a veneer of recent sediment covering pre-canyon host sediments that underpin the terraces. The combined use of state of the art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

  18. Noise in miniature microphones.

    Science.gov (United States)

    Thompson, Stephen C; LoPresti, Janice L; Ring, Eugene M; Nepomuceno, Henry G; Beard, John J; Ballad, William J; Carlson, Elmer V

    2002-02-01

    The internal noise spectrum in miniature electret microphones of the type used in the manufacture of hearing aids is measured. An analogous circuit model of the microphone is empirically fit to the measured data and used to determine the important sources of noise within the microphone. The dominant noise source is found to depend on the frequency. Below 40 Hz and above 9 kHz, the dominant source is electrical noise from the amplifier circuit needed to buffer the electrical signal from the microphone diaphragm. Between approximately 40 Hz and 1 kHz, the dominant source is thermal noise originating in the acoustic flow resistance of the small hole pierced in the diaphragm to equalize barometric pressure. Between approximately 1 kHz and 9 kHz, the noise originates in the acoustic flow resistances of sound entering the microphone and propagating to the diaphragm. To further reduce the microphone internal noise in the audio band requires attacking these sources. A prototype microphone having reduced acoustical noise is measured and discussed.

  19. Mediality is Noise

    DEFF Research Database (Denmark)

    Prior, Andrew

    This PhD is concerned with the use of noise as a material within media arts practice, especially in ‘post-digital’ contexts such as glitch electronica, glitch art and uses of old media. It examines the relationship between informational culture and noise, exploring the ways in which the structuring...

  20. Acceptable noise level

    DEFF Research Database (Denmark)

    Olsen, Steen Østergaard; Nielsen, Lars Holme; Lantz, Johannes

    2012-01-01

    The acceptable noise level (ANL) is used to quantify the amount of background noise that subjects can accept while listening to speech, and is suggested for prediction of individual hearing-aid use. The aim of this study was to assess the repeatability of the ANL measured in normal-hearing subjec...

  1. Simple models for the simulation of submarine melt for a Greenland glacial system model

    Science.gov (United States)

    Beckmann, Johanna; Perrette, Mahé; Ganopolski, Andrey

    2018-01-01

    Two hundred marine-terminating Greenland outlet glaciers deliver more than half of the annually accumulated ice into the ocean and have played an important role in the Greenland ice sheet mass loss observed since the mid-1990s. Submarine melt may play a crucial role in the mass balance and position of the grounding line of these outlet glaciers. As the ocean warms, it is expected that submarine melt will increase, potentially driving outlet glaciers retreat and contributing to sea level rise. Projections of the future contribution of outlet glaciers to sea level rise are hampered by the necessity to use models with extremely high resolution of the order of a few hundred meters. That requirement in not only demanded when modeling outlet glaciers as a stand alone model but also when coupling them with high-resolution 3-D ocean models. In addition, fjord bathymetry data are mostly missing or inaccurate (errors of several hundreds of meters), which questions the benefit of using computationally expensive 3-D models for future predictions. Here we propose an alternative approach built on the use of a computationally efficient simple model of submarine melt based on turbulent plume theory. We show that such a simple model is in reasonable agreement with several available modeling studies. We performed a suite of experiments to analyze sensitivity of these simple models to model parameters and climate characteristics. We found that the computationally cheap plume model demonstrates qualitatively similar behavior as 3-D general circulation models. To match results of the 3-D models in a quantitative manner, a scaling factor of the order of 1 is needed for the plume models. We applied this approach to model submarine melt for six representative Greenland glaciers and found that the application of a line plume can produce submarine melt compatible with observational data. Our results show that the line plume model is more appropriate than the cone plume model for simulating

  2. Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands

    Science.gov (United States)

    Watson, S. J.; Coffin, M. F.; Whittaker, J. M.; Lucieer, V.; Fox, J. M.; Carey, R.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Martin, T.; Cooke, F.

    2016-12-01

    Heard and McDonald Islands (HIMI) are World Heritage listed sub-Antarctic active volcanic islands in the Southern Indian Ocean. Built atop the Kerguelen Plateau by Neogene-Quaternary volcanism, HIMI represent subaerial exposures of the second largest submarine Large Igneous Province globally. Onshore, processes influencing island evolution include glaciers, weathering, volcanism, vertical tectonics and mass-wasting (Duncan et al. 2016). Waters surrounding HIMI are largely uncharted, due to their remote location. Hence, the extent to which these same processes shape the submarine environment around HIMI has not been investigated. In early 2016, we conducted marine geophysical and geologic surveys around HIMI aboard RV Investigator (IN2016_V01). Results show that volcanic and sedimentary features prominently trend east-west, likely a result of erosion by the eastward flowing Antarctic Circumpolar Current and tidal currents. However, spatial patterns of submarine volcanism and sediment distribution differ substantially between the islands. >70 sea knolls surround McDonald Island suggesting substantial submarine volcanism. Geophysical data reveals hard volcanic seafloor around McDonald Island, whereas Heard Island is characterised by sedimentary sequences tens of meters or more thick and iceberg scours - indicative of glacial processes. Differences in submarine geomorphology are likely due to the active glaciation of Heard Island and differing rock types (Heard: alkali basalt, McDonald: phonolite), and dominant products (clastics vs. lava). Variations may also reflect different magmatic plumbing systems beneath the two active volcanoes (Heard produces larger volumes of more focused lava, whilst McDonald extrudes smaller volumes of more evolved lavas from multiple vents across the edifice). Using geophysical data, corroborated with new and existing geologic data, we present the first geomorphic map revealing the processes that shape the submarine environment around HIMI.

  3. Health and environmental risk assessment associated with a potential recovery of the Russian submarine K-27

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, A.; Amundsen, I.; Brown, J.E.; Dowdall, M.; Standring, W. [Norwegian Radiation Protection Authority/CERAD CoE (Norway); Bartnicki, J. [Norwegian Meteorological Institute/CERAD CoE (Norway); Karcher, M. [O.A.Sys - Ocean Atmosphere Systems GmbH (Germany); Lind, O.C.; Salbu, B. [Norwegian University of Life Sciences/CERAD CoE (Norway)

    2014-07-01

    The nuclear submarine K-27 is one of several objects with spent nuclear fuel (SNF) which has been dumped in the Arctic. It contained two liquid metal reactors (LMRs) of 70 MW maximum thermal power each and used Pb-Bi as the coolant. The reactors were loaded with 180 kg of U-235 at an enrichment of 90 %. In September 1981, the submarine was sunk in the shallow waters of Stepovoy Fjord at an estimated depth of 30 m. Concerns have been expressed by various parties regarding the issue of dumped nuclear waste in the Kara Sea and in particular the submarine K-27. To address these concerns and to provide a better basis for evaluating possible radiological impact (especially as a consequence of a potential recovery of the submarine), an environmental impact assessment has been undertaken. The study is based on construction of different hypothetical accident scenarios and evaluating possible associated consequences for human and the environment. In general, three main scenarios seem probable and thus appropriate for consideration. One is the 'zero- alternative', i.e. investigate the current and future impact assuming no interventions. The second considers an accidental scenario involving the raising of the submarine and the third an accidental scenario related to the transportation of the submarine to shore for defueling. With regards to the accidental scenarios related to raising and transportation of the submarine, two alternatives can be considered depending on where and how a hypothetical accident will take place and whether the subsequent releases occur under water or at the water surface. The issue of an uncontrolled chain reaction occurring as a result of a potential recovery of the submarine will be included in the assessment. The work includes application of state of the art 3D hydrodynamic and atmospheric dispersion models to investigate the transport, distribution and fate of relevant radionuclides following a hypothetical accident in aquatic and

  4. Impact of Submarine Geohazards on Organic Carbon Burial Offshore Southwestern Taiwan

    Science.gov (United States)

    Su, C. C.; Tsai, P. H.; Liu, J. T.; Hsu, S. K.; Chiu, S. D.

    2015-12-01

    The tectonically active setting and climatic conditions give Taiwan a high exposure to severe natural hazards. After the Pingtung Earthquake and Morakot Typhoon which occurred in 2006 and 2009, the turbidity currents caused a series of submarine cable breaks along the Gaoping and Fangliao Submarine Canyons off SW Taiwan. Large amounts of terrestrial sediments were fast transported bypass the narrow continental shelf and rapidly moved southward through submarine canyons to the deep sea. Two piston cores which were taken from the Tsangyao Ridge and its adjacent area (OR5-1302-2-MT7 and MT6) might shed light on understanding the export of terrestrial organic carbon to the abyss by submarine geo-hazards. The 210Pb profile of MT7 in conjunction with the grain size data indicates the existence of the Pingtung Earthquake and Morakot Typhoon related deposits. The sedimentation rate of these two cores which derived from 210Pb is approximately 0.05 cm/yr. The cores collected from the Gaoping Submarine Canyon, Gaoping Slope and Fangliao Submarine Canyon are used for analyzing TOC, organic C/N and δ13C ratios. The concentrations of total organic carbon are ~0.5%, and C/N rations almost remain between 4 and 8. The high TOC (~1%) and C/N ratio (>10) are observed in the samples with plant debris. The fluctuation of TOC and C/N ratios in near-shore samples is higher than deep sea. In terms of δ13C-values, it progressively decreases with distances from coastal zone to the deep sea. Due to the larger proportions of land-derived organic carbon, the δ13C-values in the surface sediment of upper Gaoping Submarine Canyon, Gaoping Slope, and the turbidite layers at the head of Fangliao Submarine Canyon are lighter. Furthermore, we use the TOC concentrations and δ13C-values to estimate the fractional contributions of terrestrial organic carbon by a simple two component mixing model, and integrate with the 210Pb-derived sediment accumulation rates to evaluate the organic carbon burial

  5. Nuclear-powered submarine accidents; Les accidents de sous-marins nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Tournyol du Clos, A.

    1996-04-01

    Most of nuclear-powered ships are military ships and submarines represent 95% of the total. Most of the propulsion reactors used are of PWR type. This paper gives the principal technical characteristics of PWR ship propulsion reactors and the differences with their civil homologues. The principal accidents that occurred on US and Russian nuclear-powered submarines are also listed and the possible effects of a shipwreck on the reactor behaviour are evaluated with their environmental impact. (J.S.). 1 tab., 1 photo.

  6. Modeling and Synthesis Methods for Retrofit Design of Submarine Actuation Systems. Energy Storage for Electric Actuators

    Science.gov (United States)

    2011-12-15

    sternplane v - sway w - heave u - surge X Y Z y z x Figure 2: Coordinate frame definitions of submarine vehicular dynamics. 2.1 Six Degree of Freedom...where Mν̇ is the total inertial matrix, C(ν) is the Coriolis/centripetal matrix, D(ν) is the total damping matrix, g(η) are the buoyancy and weight...Natick, MA. Retrofit Design of Submarine Actuation Systems Page 7 q - pitch w - heave u - surge δs Msp Figure 3: Hydrodynamic moment unit definition

  7. The impact of the Type 094 ballistic missile submarine on China's nuclear policy

    OpenAIRE

    Bell, Samuel D.

    2009-01-01

    Approved for public release, distribution unlimited This thesis examines the implication of China’s near completion of a viable nuclear triad. The objective is to determine first, how this submarine will fit into China’s no-first-use policy with regards to their nuclear weapons. And second, determine how advanced this weapon platform will be. With the introduction of multiple Type 094 “Jin” class ballistic missile submarines, has Beijing set the stage for a possible return to Cold War leve...

  8. Oceanographic studies supporting the assessment of deep-sea disposal of defueled decommissioned nuclear submarines

    Science.gov (United States)

    Ross Heath, G.; Rea, David K.; Ness, Gordon; Dale Pillsbury, R.; Beasley, Thomas M.; Lopez, Carlos; Talbert, Daniel M.

    1984-12-01

    Based on criteria developed by the international Atomic Energy Agency (IAEA), potential disposal sites for defueled, decommissioned nuclear submarines appear to exist in deep water south of the Mendocino Fracture Zone within 200 nautical miles of the United States Oceanographic measurements in the water column and at the sea floor in a study area (W-N) at 39 5°N, 127 5°W will allow the operational and radiological consequences of deep-sea disposal to be compared with land burial of old submarines. The W-N studies also are yielding new data that will provide insights to the deposition and early diagenesis of distal hemipelagic sediments

  9. Submarine landslide triggered by eruption recorded by in-situ hydrophone at NW Rota-1 submarine volcano, Mariana Arc (Invited)

    Science.gov (United States)

    Chadwick, B.; Dziak, R. P.; Embley, R. W.; Tunnicliffe, V.; Sherrin, J.; Cashman, K. V.; Deardorff, N.

    2010-12-01

    An expedition to NW Rota-1, Mariana Arc, in March 2010 with R/V Kilo Moana and ROV Jason found that the submarine volcano (summit depth 520 m) was still erupting more or less continuously as has been observed since 2004, In addition, the expedition also discovered that a major landslide had occurred since the last visit in April 2009, demonstrating the dynamic processes of eruption, collapse, and regrowth in the submarine arc environment. The dive observations reveal the responses of the volcano’s magmatic and hydrothermal systems to such a collapse, as well as how the resident chemosynthetic biological community has responded to the event. The morphologic changes from the landslide can be quantified by comparing multibeam bathymetric surveys between 2009 and 2010. The headwall of the slide is now ~100 m north of the former summit ridge where depth changes up to -90 m occurred between surveys. The slide excavated material from the upper southern slope of the volcano to a distance of 3.5 km downslope, and deposited material between 2-8 km from the summit down to at least 2800 m on the volcano flank. The area and volume of slide deposits (positive depth changes) are 7.1 x 106 m2 and 5.3 x 107 m3, respectively, and the maximum thickness is +42 m. The area and volume of material removed by the slide (negative depth changes) are 2.2 x 106 m2 and -4.1 x 107 m3, respectively. We have found no evidence for a local tsunami generated by this event. The changes in morphology near the summit show that the landslide primarily removed loose volcaniclastic deposits that had accumulated near the active eruptive vent, exposing an underlying stock-like core of resistant intrusive rocks and massive lavas at the summit. During March 2010, there were at least 5 active eruptive vents, located along a line 200-m long, that changed between active and inactive day-to-day and even hour-to-hour, suggesting that the near-surface magmatic plumbing system was still reorganizing after the

  10. CT radiation dose and iterative reconstruction techniques

    National Research Council Canada - National Science Library

    Padole, Atul; Ali Khawaja, Ranish Deedar; Kalra, Mannudeep K; Singh, Sarabjeet

    2015-01-01

    .... CT image quality is dependent on the selected image reconstruction algorithm. 3. Iterative reconstruction algorithms have reemerged with the potential of radiation dose optimization by lowering image noise. 4...

  11. Underwater noise due to precipitation

    DEFF Research Database (Denmark)

    Crum, Lawrence A.; Pumphrey, Hugh C.; Prosperetti, Andrea

    1989-01-01

    of this bubble resulted in a large amount of radiated sound. Recently, Scrimger has measured the underwater sound produced by rainfall and has discovered that a well-defined spectral peak exists near 15 kHz [J. A. Scrimger, Nature 318, 647 (1985)]. The sound produced by the impact of water droplets on a water......In 1959, G. Franz published a thorough investigation of the underwater sound produced by liquid drop impacts [G. Franz, J. Acoust. Soc. Am. 31, 1080 (1959)]. He discovered that, under certain conditions, a gas bubble was entrained by the impacting droplet, and the subsequent oscillation...... surface, both for individual and for multiple events such as those produced by artificial and natural rainfall, has been examined. The studies indicate that the major contribution to the underwater noise produced by both rain and snow is that associated with the oscillations of gas bubbles introduced...

  12. Effects of background noise on total noise annoyance

    Science.gov (United States)

    Willshire, K. F.

    1987-01-01

    Two experiments were conducted to assess the effects of combined community noise sources on annoyance. The first experiment baseline relationships between annoyance and noise level for three community noise sources (jet aircraft flyovers, traffic and air conditioners) presented individually. Forty eight subjects evaluated the annoyance of each noise source presented at four different noise levels. Results indicated the slope of the linear relationship between annoyance and noise level for the traffic noise was significantly different from that of aircraft and of air conditioner noise, which had equal slopes. The second experiment investigated annoyance response to combined noise sources, with aircraft noise defined as the major noise source and traffic and air conditioner noise as background noise sources. Effects on annoyance of noise level differences between aircraft and background noise for three total noise levels and for both background noise sources were determined. A total of 216 subjects were required to make either total or source specific annoyance judgements, or a combination of the two, for a wide range of combined noise conditions.

  13. Noise and Hearing Loss Prevention

    Science.gov (United States)

    ... visit this page: About CDC.gov . NOISE AND HEARING LOSS PREVENTION Recommend on Facebook Tweet Share Compartir Hearing ... noise levels cannot be adequately reduced. Noise and Hearing Loss on the NIOSH Science Blog Read and comment ...

  14. Airframe Noise Prediction Using the Sngr Method

    Science.gov (United States)

    Chen, Rongqian; Wu, Yizhao; Xia, Jian

    In this paper, the Stochastic Noise Generation and Radiation method (SNGR) is used to predict airframe noise. The SNGR method combines a stochastic model with Computational Fluid Dynamics (CFD), and it can give acceptable noise results while the computation cost is relatively low. In the method, the time-averaged mean flow field is firstly obtained by solving Reynolds Averaged Navier-Stokes equations (RANS), and a stochastic velocity is generated based on the obtained information. Then the turbulent field is used to generate the source for the Acoustic Perturbation Equations (APEs) that simulate the noise propagation. For numerical methods, timeaveraged RANS equations are solved by finite volume method, and the turbulent model is K - ɛ model; APEs are solved by finite difference method, and the numerical scheme is the Dispersion-Relation-Preserving (DRP) scheme, with explicit optimized 5-stage Rung-Kutta scheme time step. In order to test the APE solver, propagation of a Gaussian pulse in a uniform mean flow is firstly simulated and compared with the analytical solution. Then, using the method, the trailing edge noise of NACA0012 airfoil is calculated. The results are compared with reference data, and good agreements are demonstrated.

  15. Substation noise screening tool

    Energy Technology Data Exchange (ETDEWEB)

    Maybee, Nigel; Everton, Pascal [HFP Acoustical Consultants Corp. (Canada)], email: nigel.maybee@hfpacoustical.com; Chow, Vincent [Altalink Management Ltd. (Canada)], email: Vincent.Chow@AltaLink.ca

    2011-07-01

    Alberta noise regulations require energy-related facilities to conduct predictions on sound levels, especially for large and medium noise sources. This is usually done with well-known modelling software, but that can be disadvantageous when assessing the noise impact of smaller noise sources, such as transformer substations. This paper focuses on the development of a spreadsheet substation noise screening tool to assess the noise impact of a small transformer substation with precision and ease-of-use. Three aspects must be considered: transformer sound levels, which can be provided by the manufacturer or extracted from accepted sound level references; sound power calculations, which depend on the substation size and operating regime; and sound propagation calculations, which take into account the distance of the receptor from the substation and sound absorption by the air and ground. Comparison of results obtained with this tool with results generated by standard sound modelling software shows the utility, accuracy and ease-of-use of this screening method for assessing the noise impact of transformer substations.

  16. Pneumatic muffler noise.

    Science.gov (United States)

    Cudworth, A L; Hanson, W J; Vuisting, W

    1978-11-01

    Sixty-five commercial pneumatic mufflers in the size range of 1/8 to 3/8-inch American Standard Taper Pipe Thread (NPT) were evaluated for noise level as a function of air supply pressure and back pressure. Also, typical directivity pattern and spectral content were determined. A rating system has been devised, as well as individual prediction formulas, to rank order the mufflers and provide a capability of calculating expected noise levels for a given supply pressure. As this study reveals, noise reductions in excess of 40 dBA may be achieved by employing an efficient pneumatic muffler.

  17. Controlled Noise Seismology

    KAUST Repository

    Hanafy, Sherif M.

    2015-08-19

    We use controlled noise seismology (CNS) to generate surface waves, where we continuously record seismic data while generating artificial noise along the profile line. To generate the CNS data we drove a vehicle around the geophone line and continuously recorded the generated noise. The recorded data set is then correlated over different time windows and the correlograms are stacked together to generate the surface waves. The virtual shot gathers reveal surface waves with moveout velocities that closely approximate those from active source shot gathers.

  18. Swath sonar mapping of Earth's submarine plate boundaries

    Science.gov (United States)

    Carbotte, S. M.; Ferrini, V. L.; Celnick, M.; Nitsche, F. O.; Ryan, W. B. F.

    2014-12-01

    The recent loss of Malaysia Airlines flight MH370 in an area of the Indian Ocean where less than 5% of the seafloor is mapped with depth sounding data (Smith and Marks, EOS 2014) highlights the striking lack of detailed knowledge of the topography of the seabed for much of the worlds' oceans. Advances in swath sonar mapping technology over the past 30 years have led to dramatic improvements in our capability to map the seabed. However, the oceans are vast and only an estimated 10% of the seafloor has been mapped with these systems. Furthermore, the available coverage is highly heterogeneous and focused within areas of national strategic priority and community scientific interest. The major plate boundaries that encircle the globe, most of which are located in the submarine environment, have been a significant focus of marine geoscience research since the advent of swath sonar mapping. While the location of these plate boundaries are well defined from satellite-derived bathymetry, significant regions remain unmapped at the high-resolutions provided by swath sonars and that are needed to study active volcanic and tectonic plate boundary processes. Within the plate interiors, some fossil plate boundary zones, major hotspot volcanoes, and other volcanic provinces have been the focus of dedicated research programs. Away from these major tectonic structures, swath mapping coverage is limited to sparse ocean transit lines which often reveal previously unknown deep-sea channels and other little studied sedimentary structures not resolvable in existing low-resolution global compilations, highlighting the value of these data even in the tectonically quiet plate interiors. Here, we give an overview of multibeam swath sonar mapping of the major plate boundaries of the globe as extracted from public archives. Significant quantities of swath sonar data acquired from deep-sea regions are in restricted-access international archives. Open access to more of these data sets would

  19. Submarine Groundwater Discharge in Stony Brook Harbor, NY

    Science.gov (United States)

    Durand, J. M.; Young, C.; Wong, T.; Hanson, G. N.

    2012-12-01

    As nutrients can significantly impact coastal ecosystems, understanding their path to embayments and oceans is crucial. In Stony Brook Harbor (Long Island, NY), submarine groundwater discharge (SGD) is the only significant contribution of freshwater and thus constitutes the main pathway for nutrients, which may eventually reach Long Island Sound. Subterranean estuaries have been shown to be highly reactive zones where nitrogen attenuation can occur. Understanding the fate of nitrogen in Stony Brook Harbor requires knowing the volume of groundwater entering the bay as well as the amount of denitrification, in the context of the hydrogeological framework. This is achieved by combining electrical resistivity survey, water sampling in piezometers, point conductivity and seepage measurements. A Trident probe inserted 60 cm deep into the sediments allows measuring the conductivity and temperature of the sediments and the overlying seawater. In spring 2011, five Trident transects spreading across the head of the harbor were used as a preliminary study to reveal potential locations for SGD. Locations with significant difference between sediment and seawater temperature and/or conductivities were further investigated using an AGI SuperSting 8-channel receiver resistivity meter. Two ultrasonic seepage meters were deployed in May and July 2011 about 20 m below the low tide mark. Five piezometers were aligned parallel to one resistivity survey. Our resistivity data indicate superficial mixing in the intertidal zone. The freshwater extends quite far under the seafloor, above 67 meters after the low tide mark for one location. The freshwater/saltwater interface seems to be almost horizontal. The piezometer data agree relatively well with the resistivity data. The preliminary average seepage rates observed vary from 3 to 60 cm/d. The resistivity sections reveal the presence of a thin layer of high conductivity above the low tide mark. This matches the observation of a superficial

  20. Radiation Therapy

    Science.gov (United States)

    ... Be extra careful not to spend time with children or pregnant women. Internal Radiation Therapy Makes You Give Off Radiation With systemic radiation, your body fluids ( urine , sweat, and saliva ) will give off radiation for a while. With ...

  1. Radiation enteritis

    Science.gov (United States)

    Radiation enteropathy; Radiation-induced small bowel injury; Post-radiation enteritis ... Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. The therapy ...

  2. Cochlear implant optimized noise reduction

    Science.gov (United States)

    Mauger, Stefan J.; Arora, Komal; Dawson, Pam W.

    2012-12-01

    Noise-reduction methods have provided significant improvements in speech perception for cochlear implant recipients, where only quality improvements have been found in hearing aid recipients. Recent psychoacoustic studies have suggested changes to noise-reduction techniques specifically for cochlear implants, due to differences between hearing aid recipient and cochlear implant recipient hearing. An optimized noise-reduction method was developed with significantly increased temporal smoothing of the signal-to-noise ratio estimate and a more aggressive gain function compared to current noise-reduction methods. This optimized noise-reduction algorithm was tested with 12 cochlear implant recipients over four test sessions. Speech perception was assessed through speech in noise tests with three noise types; speech-weighted noise, 20-talker babble and 4-talker babble. A significant speech perception improvement using optimized noise reduction over standard processing was found in babble noise and speech-weighted noise and over a current noise-reduction method in speech-weighted noise. Speech perception in quiet was not degraded. Listening quality testing for noise annoyance and overall preference found significant improvements over the standard processing and over a current noise-reduction method in speech-weighted and babble noise types. This optimized method has shown significant speech perception and quality improvements compared to the standard processing and a current noise-reduction method.

  3. Fusion of synthetic aperture radiometer and noise waveform SAR images

    OpenAIRE

    Lukin, Konstantin A.; Kudriashov, V. V.

    2014-01-01

    Noise waveform SAR generates 2D SAR images of a scene. Advanced radiometric SAR imaging provides information on the objects thermal radiation, angular coordinates and even range. The brightness temperatures of rough and smooth surfaces are different. An active, noise waveform, operating mode of bistatic radiometer, based on antennae with beam synthesis, is considered with respect to the roughness criteria. The optimal and quasi-optimal algorithms for fusion of radiometric and SAR images are p...

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

    Directory of Open Access Journals (Sweden)

    D. Ratner

    2015-05-01

    Full Text Available 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 undulator radiation, demonstrating the feasibility of noise suppression as a practical tool in accelerator physics.

  5. Comparison of effective noise temperatures in YBa2BCu3O7-δ junctions

    DEFF Research Database (Denmark)

    Fischer, Gerd Michael; Mygind, Jesper; Pedersen, Niels Falsig

    1997-01-01

    The dc voltage response to 70 GHz radiation was measured for YBCO bicrystal junctions, step edge junctions and ramp edge junctions at temperatures from 4 K to 90 K. Employing the RSJ-model and assuming thermal noise, the Josephson radiation is about equal to the voltage difference of the voltage...... response to the small signal microwave irradiation. In the presence of excess noise, an effective noise temperature can be defined and is used as a figure of merit. In bicrystal grain boundary junctions with zero magnetic field the effective noise temperature was determined to be equal to the physical...

  6. Potential Impact of Atmospheric Releases at Russian Far East Nuclear Submarine Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Parker, F.; Mahura, A.; Compton, K.; Brown, K.; Takano, M.; Novikov, V.; Soerensen, J. H.; Baklanov, A.

    2003-02-25

    An ''Assessment of the Impact of Russian Nuclear Fleet Operations on Far Eastern Coastal Regions'' is being performed as part of the Radiation Safety of the Biosphere Project (RAD) of the International Institute for Applied Systems Analysis (IIASA) of Laxenburg, Austria. To the best of our knowledge, this is the first comprehensive unclassified analysis of the potential impact of accidents at the Russian Far East nuclear submarine sites near Vladivostok and Petropavlovsk. We have defined the situation there based upon available information and studies commissioned by RAD in collaboration with Russian research institutes including Russian Research Center-''Kurchatov Institute'', Institute of Northern Environmental Problems and Lazurit Central Design Bureau. Further, in our original work, some in collaboration with the staff of the Danish Meteorological Institute (DMI) and members of the Japan Atomic Energy Research Institute, we have calculated the nuclide trajectories from these sites in the atmospheric boundary layer, less than 1.5 kilometers high, and determined their probability of crossing any of the nearby countries as well as Asiatic Russia. We have further determined the concentrations in each of these crossings as well as the total, dry and wet depositions of nuclides on these areas. Finally, we have calculated the doses to the Japanese Island population from typical winter airflow patterns (those most likely to cross the Islands in the minimum times), strong north winds, weak north winds and cyclonic winds for conditions similar to the Chazhma Bay criticality accident (fresh fuel) and for a criticality accident for the same type of reactor with fuel being withdrawn (spent fuel). The maximum individual committed dosages were less than 2 x 10-7 and 2 x 10-3 mSv, respectively. The long-term external doses by radionuclides deposited on the ground and the internal doses by consumption of foods were not evaluated as it is

  7. Active structural acoustic control of repetitive impact noise

    Science.gov (United States)

    Pinte, G.; Boonen, R.; Desmet, W.; Sas, P.

    2009-01-01

    This paper discusses the effectiveness of an Active Structural Acoustic Control (ASAC) system for the reduction of repetitive impact noise, radiated by structures with a high modal density in the controlled frequency range. Although there is a significant difference in nature between periodic and transient noise, up till now no specific research on ASAC of transient noise was reported. The development of the ASAC system is divided into two phases: the definition of the control configuration and the design of a suitable control algorithm. The optimal control configuration as well as the implemented control algorithm for the reduction of impact noise differ significantly from the common solutions in periodic noise control. In the first part of the paper, a practical methodology is presented to define a good control arrangement for transient noise control. The second part of the paper focuses on the design of control algorithms, adapted to the specific properties of impact noise. Since many industrial impact noise problems involve successive impacts with a repetitive behaviour, control algorithms with a learning behaviour are discussed. The efficiency of these Iterative Learning Control (ILC) algorithms is extensively demonstrated in this paper. The developed ASAC strategy has been verified on a thick steel plate, which is excited by successive impacts. The obtained results show that ASAC can be a very efficient transient noise control technique in certain industrial applications (e.g. presses, punching machines, etc.).

  8. Applicability of RANS, DES and LES in propeller flow noise

    Directory of Open Access Journals (Sweden)

    LU Li

    2017-12-01

    Full Text Available [Objectives] In order to study the applicability of different turbulence models in propeller flow noise prediction, taking the DTMB 4119 propeller as the research object, the numerical simulation method is used to calculate the frequency domain noise under the non-uniform flow field.[Methods] First, the hydrodynamic coefficient and surface pressure distribution coefficient are obtained via the RANS method and the accuracy of the flow field simulation is verified by comparing it with the experimental data. Next,the pulsating pressures obtained by RANS, DES and LES are considered as the sound source respectively, and combined with the acoustic boundary element method to predict the radiation noise.[Results] The results show that spectral noise is the main contributor to total noise; when noise on 1 BPF is predicted, the results obtained by the three methods are very similar, so we can use RANS to predict noise quickly; when noise on the high order of BPF needs to be predicted, the calculation results of LES are better.[Conclusions] In noise prediction, the appropriate turbulence simulation method can be selected according to the demand.

  9. The Italian Submarine Force in the Battle of the Atlantic: Left in the Dark

    Science.gov (United States)

    2014-12-12

    design during the Interwar period. Part of this discussion will focus on German U-boat design and capabilities prior to the Versailles Treaty in...patrols can be attributed to the restrictions imposed by the Treaty of Versailles and the amount of time required to re-build a German submarine force...

  10. Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system.

    Science.gov (United States)

    Rizzo, Andrea Luca; Caracausi, Antonio; Chavagnac, Valèrie; Nomikou, Paraskevi; Polymenakou, Paraskevi N; Mandalakis, Manolis; Kotoulas, Georgios; Magoulas, Antonios; Castillo, Alain; Lampridou, Danai

    2016-06-17

    Submarine volcanism represents ~80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report (3)He/(4)He measurements in CO2-dominated gases discharged at 500 m below sea level from the high-temperature (~220 °C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a (3)He/(4)He signature of at least 7.0 Ra (being Ra the (3)He/(4)He ratio of atmospheric He equal to 1.39×10(-6)), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like (3)He/(4)He ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano.

  11. The fate of the submarine ikaite tufa columns in southwest Greenland under changing climate conditions

    DEFF Research Database (Denmark)

    Hansen, Marc O.; Buchardt, Bjørn; Kühl, Michael

    2011-01-01

    carbonate tufa columns. Here, ikaite is formed as a result of submarine spring water mixing with cold seawater. As ikaite disintegrates at temperatures above 6–7uC, it has been speculated that global warming could endanger this unique habitat as well as other sites. In Ikka Fjord in situ water chemistry...

  12. Frontal and Lateral Submarine Lobe Fringes: Comparing Sedimentary Facies, Architecture and Flow Processes

    NARCIS (Netherlands)

    Spychala, Yvonne T.; Hodgson, David M.; Prélat, Amandine; Kane, Ian A.; Flint, Stephen S.; Mountney, Nigel P.

    2017-01-01

    Submarine lobe-fringe deposits form heterolithic successions that may include a high proportion of hybrid beds. The identification of lobe-fringe successions aids interpretation of paleogeographic setting and the degree of basin confinement. Here, for the first time, the sedimentological and

  13. Contributions for the modelling of submarine cables – current density and simplified modelling of wired layers

    DEFF Research Database (Denmark)

    Silva, Filipe Miguel Faria da; Bak, Claus Leth; Ebdrup, Thomas

    2015-01-01

    This article researches two topics relevant for the development of accurate formulae able to estimate the ampacity of HVAC submarine cables. Simplified formulae for estimating the current density distribution, which can be used for theoretical analyses, are developed and compared with the exact...

  14. The Future of the Ballistic Missile Submarine Force in the Russian Nuclear Triad

    Science.gov (United States)

    2008-09-01

    financial setbacks, missile technology failures, and the Kursk sinking in 2000, the SSBN force has slipped back to a lesser prominence.9 B. MAJOR...range category. In the battle for survival, the SLBMs and ALCMs are the most likely potential losers. When the two platforms – submarines and

  15. Scientific Ocean Drilling Behind the Assessment of Geo-Hazards from Submarine Slides

    Directory of Open Access Journals (Sweden)

    Gemma Ercilla

    2007-03-01

    Full Text Available The workshop ‘Scientific Ocean Drilling Behind the Assessment of Geo-hazards from Submarine Slides’ was held on 25–27 October 2006 in Barcelona (Spain. Fifty mainly European scientists and industry representatives attended from a wide spectrum of disciplines such as geophysics, stratigraphy, sedimentology, paleoceanography, marinegeotechnology, geotechnical engineering, and tsunami modeling.

  16. Estimation of submarine mass failure probability from a sequence of deposits with age dates

    Science.gov (United States)

    Geist, Eric L.; Chaytor, Jason D.; Parsons, Thomas E.; ten Brink, Uri S.

    2013-01-01

    The empirical probability of submarine mass failure is quantified from a sequence of dated mass-transport deposits. Several different techniques are described to estimate the parameters for a suite of candidate probability models. The techniques, previously developed for analyzing paleoseismic data, include maximum likelihood and Type II (Bayesian) maximum likelihood methods derived from renewal process theory and Monte Carlo methods. The estimated mean return time from these methods, unlike estimates from a simple arithmetic mean of the center age dates and standard likelihood methods, includes the effects of age-dating uncertainty and of open time intervals before the first and after the last event. The likelihood techniques are evaluated using Akaike’s Information Criterion (AIC) and Akaike’s Bayesian Information Criterion (ABIC) to select the optimal model. The techniques are applied to mass transport deposits recorded in two Integrated Ocean Drilling Program (IODP) drill sites located in the Ursa Basin, northern Gulf of Mexico. Dates of the deposits were constrained by regional bio- and magnetostratigraphy from a previous study. Results of the analysis indicate that submarine mass failures in this location occur primarily according to a Poisson process in which failures are independent and return times follow an exponential distribution. However, some of the model results suggest that submarine mass failures may occur quasiperiodically at one of the sites (U1324). The suite of techniques described in this study provides quantitative probability estimates of submarine mass failure occurrence, for any number of deposits and age uncertainty distributions.

  17. CLAM - CoLlAborative eMbedded networks for submarine surveillance: An overview

    NARCIS (Netherlands)

    Meratnia, Nirvana; Havinga, Paul J.M.; Casari, Paolo; Petrioli, Chiara; Grythe, Knut; Husoy, Thor; Zorzi, Michele

    2011-01-01

    This paper provides an overview of the CLAM project, which aims at developing a collaborative embedded monitoring and control platform for submarine surveillance by combining cutting edge acoustic vector sensor technology and 1D, 2D, 3D sensor arrays, underwater wireless sensor networks protocol

  18. Terrestrial-style slow-moving earthflow kinematics in a submarine landslide complex

    Science.gov (United States)

    Joshu J. Mountjoy; Jim McKean; Philip M. Barnes; Jarg R. Pettinga

    2009-01-01

    Morphometric analysis of Simrad EM300 multibeam bathymetric DEMs reveals details of deformation patterns in a ~145 km2 submarine landslide complex that are commonly associated with slow-moving earthflows in terrestrial settings. This mode of failure, where existing landslide debris is remobilised repeatedly along discrete shear boundaries and is...

  19. Exchange Flow of Oil and Sea-Water in a Ruptured Submarine Pipeline

    NARCIS (Netherlands)

    Kranenburg, C.

    1983-01-01

    The rupture of a submarine oil pipeline starts var10US mechanisms leading to an oil spill. Among these mechanisms the leakage of oil driven by the difference in specific gravities of oil and seawater is difficult to quantify. A simple mathematical model has been developed and laboratory experiments

  20. Buoyancy-driven leakage of oil from a ruptured submarine pipeline

    NARCIS (Netherlands)

    Kranenburg, C.

    1983-01-01

    The rupture of a submarine oil pipeline starts various mechanisms leading to an oil spill. Among these mechanisms the leakage of oil driven by the difference in specific gravities of oil and sea-water is difficult to estimate. A simple mathematical model has been developed and laboratory experiments

  1. Geochemical stratigraphy of submarine lavas (3-5 Ma) from the Flamengos Valley, Santiago, Cape Verde

    DEFF Research Database (Denmark)

    Barker, Abigail K; Holm, Paul Martin; Peate, David W.

    2009-01-01

    New high-precision Pb-Sr-Nd isotope, major and trace element and mineral chemistry data are presented for the submarine stage of ocean island volcanism on Santiago, one of the southern islands of the Cape Verde archipelago. Pillow basalts and hyaloclastites in the Flamengos Valley are divided...

  2. Common Submarine Radio Room: A Case Study of a System of Systems Approach

    Science.gov (United States)

    2014-09-01

    11. Land Attack/Strike Mission Scenario (from PMW770 2011b, 52) .................30 Figure 12. CSG/ ESG Mission Scenario (from PMW770 2011b, 67...request EHF extremely high frequency ESG expeditionary strike group ETR Submarine communications electronics technician FRD Fleet readiness...expeditionary strike group operations mission (CSG/ ESG ) 4. Special operations forces mission (SOF) 5. Mine warfare operations mission (MIW) 6

  3. Mapping submarine sand waves with multiband imaging radar - 2. Experimental results and model comparison

    NARCIS (Netherlands)

    Vogelzang, J.; Wensink, G.J.; Calkoen, C.J.; Kooij, M.W.A. van der

    1997-01-01

    On August 16, 1989, and on July 12, 1991, experiments were performed to study the mapping of submarine sand waves with the airborne imaging radar, a polarimetric (and, in 1991, interferometric) airborne P, L, and C band synthetic aperture radar system. The experiments took place in an area 30 km off

  4. Adaptation of a submarine transient detector to the detection of whale sounds

    NARCIS (Netherlands)

    Hotho, G.H.

    1999-01-01

    As part of an international effort to investigate a potential link between acoustic trials (SWAC 4) of SACLANTCEN with a stranding of Cuvier's beaked whales on the Greek coast in May 1996. TNO-FEL's Transient Detection Demonstrator (TDD). a tool to automatically search for submarine transients in

  5. The Risk of Hydrogen Explosion an a Submarine Part 3 Production of Hydrogen Mixes

    Directory of Open Access Journals (Sweden)

    Kłos Ryszard

    2017-03-01

    Full Text Available This series of articles presents the problems associated with the conduction of a high-risk project aimed at modernising the hydrogen combustion engines on a submarine. The article describes technical issues connected with obtaining hydrogen-air mixes.

  6. Global land-ocean linkage: direct inputs of nitrogen to coastal waters via submarine groundwater discharge

    NARCIS (Netherlands)

    Beusen, A.H.W.; Slomp, C.P.; Bouwman, A.F.

    2013-01-01

    The role of submarine groundwater discharge (SGD), the leakage of groundwater from aquifers into coastal waters, in coastal eutrophication has been demonstrated mostly for the North American and European coastlines, but poorly quantified in other regions. Here, we present the first spatially

  7. Possible climate preconditioning on submarine landslides along a convergent margin, Nankai Trough (NE Pacific)

    Science.gov (United States)

    Kremer, Katrina; Usman, Muhammed O.; Satoguchi, Yasufumi; Nagahashi, Yoshitaka; Vadakkepuliyambatta, Sunil; Panieri, Giuliana; Strasser, Michael

    2017-12-01

    Submarine landslides are major agents of sediment mass transfer from the shallow to deep sea. Due to their rapid emplacement and tsunamigenic potential, such landslides are significant geohazards for society and off- and on-shore infrastructure. The relationship between climate change and the occurrence of submarine landslides is widely debated. However, there is a lack of continuous long-term submarine landslide records with which to comprehensively understand the relationship between climate-driven forces and submarine landslide occurrence. Here, using oxygen isotope stratigraphy in combination with tephrochronology, we date a 1 Myr continuous record of six landslide deposits (at 13.0-14.2, 323-339, 372-384, 394-413, 508-521, and 857-867 ka) recorded in a slope basin of the Nankai Trough subduction zone, off-shore Japan, which represents the major outcome of this study. The ages of the six landslides coincide mostly with interglacial periods. Thus, we propose that climate forcing might act as a preconditioning factor for slope instability in this active tectonic region.[Figure not available: see fulltext.

  8. Near-bottom particulate matter dynamics in the Nazare submarine canyon under calm and stormy conditions

    NARCIS (Netherlands)

    Martín, J.; Palanques, A.; Vitorino, J.; Oliveira, A.; de Stigter, H.C.

    2011-01-01

    Two mooring lines equipped with near-bottom sediment traps were deployed in the axis of the Nazare submarine canyon at similar to 1600 and similar to 3300 m depth, respectively. We studied time-series of particle flux, composition (biogenic silica, carbonates, organic matter and lithogenic

  9. Autonomous long-term gamma-spectrometric monitoring of submarine groundwater discharge trends in Hawaii

    Czech Academy of Sciences Publication Activity Database

    Dulai, H.; Kameník, Jan; Waters, C. A.; Kennedy, J.; Babinec, J.; Jolly, J.; Williamson, M.

    2016-01-01

    Roč. 307, č. 3 (2016), s. 1865-1870 ISSN 0236-5731. [10th International Conference on Methods and Applications of Radioanalytical Chemistry (MARC). Kailua Kona, 12.04.2015-17.04.2015] Institutional support: RVO:61389005 Keywords : submarine groundwater discharge * long-term SGD monitoring * underwater gammaspectrometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.282, year: 2016

  10. Probabilistic Hazard of Tsunamis Generated by Submarine Landslides in the Cook Strait Canyon (New Zealand)

    Science.gov (United States)

    Lane, Emily M.; Mountjoy, Joshu J.; Power, William L.; Mueller, Christof

    2016-12-01

    Cook Strait Canyon is a submarine canyon that lies within ten kilometres of Wellington, the capital city of New Zealand. The canyon walls are covered with scars from previous landslides which could have caused local tsunamis. Palaeotsunami evidence also points to past tsunamis in the Wellington region. Furthermore, the canyon's location in Cook Strait means that there is inhabited land in the path of both forward- and backward-propagating waves. Tsunamis induced by these submarine landslides pose hazard to coastal communities and infrastructure but major events are very uncommon and the historical record is not extensive enough to quantify this hazard. The combination of infrequent but potentially very consequential events makes realistic assessment of the hazard challenging. However, information on both magnitude and frequency is very important for land use planning and civil defence purposes. We use a multidisciplinary approach bringing together geological information with modelling to construct a Probabilistic Tsunami Hazard Assessment of submarine landslide-generated tsunami. Although there are many simplifying assumptions used in this assessment, it suggests that the Cook Strait open coast is exposed to considerable hazard due to submarine landslide-generated tsunamis. We emphasise the uncertainties involved and present opportunities for future research.

  11. Beam propagation of tidal internal waves over a submarine slope of the Mascarene Ridge

    Science.gov (United States)

    Morozov, E. G.; Nechvolodov, L. V.; Sabinin, K. D.

    2009-12-01

    The generation of internal tides over the Mascarene Ridge is studied on the basis of moored measurements and numerical modeling. The beam structure of the internal wave propagation over a submarine ridge is analyzed. The dependence of the beam propagation of the perturbations on the steepness of the slope, the depth of the ridge crest, and the stratification is studied.

  12. Noble gas systematics of submarine alkalic lavas near the Hawaiian hotspot

    NARCIS (Netherlands)

    Hanyu, T.; Clague, D.A.; Kaneoka, I.; Dunai, T.J.; Davies, G.R.

    2005-01-01

    Noble gas isotopic ratios were determined for submarine alkalic volcanic rocks distributed around the Hawaiian islands to constrain the origin of such alkalic volcanism and hence understand the details of mantle upwelling beneath Hawaii. Samples were collected by dredging or using submersibles from

  13. Submarine groundwater discharge within a landslide scar at the French Mediterranean coast

    Science.gov (United States)

    Oehler, Till; Mogollón, José M.; Moosdorf, Nils; Winkler, Andreas; Kopf, Achim; Pichler, Thomas

    2017-11-01

    Submarine groundwater discharge (SGD), the flow of fresh and saline groundwater from the seabed into the coastal ocean, has been intensively investigated in the recent years. This research has usually been restricted to shallow water and intertidal areas, whereas knowledge about groundwater seepage in deeper water is mainly limited to point sources from karstic aquifers. In this study we observed submarine groundwater seepage and a subterranean estuary in sediments at water depths of 20-44 m located within the Ligurian Margin, western Mediterranean Sea. Here, a catastrophic submarine landslide occurred near the Nice airport (French Ligurian coast) in the fall of 1979 after a period of heavy rainfall. During two research cruises, gravity cores were recovered in and around the area of the landslide scar. Pore water samples collected from sediment cores indicated sediments containing freshwater within the landslide scar. Pore water profiles of selected ions, such as chloride, ammonium, manganese, sulfate and barium were used to assess transport and reaction processes within the sediment. A 1-dimensional transport model indicates in most cores upward pore water velocities of 2.3-8.8 cm yr-1. This study shows that submarine groundwater seepage along the French Mediterranean coastline can occur at water depths reaching 44 m.

  14. Airframe noise prediction evaluation

    Science.gov (United States)

    Yamamoto, Kingo J.; Donelson, Michael J.; Huang, Shumei C.; Joshi, Mahendra C.

    1995-01-01

    The objective of this study is to evaluate the accuracy and adequacy of current airframe noise prediction methods using available airframe noise measurements from tests of a narrow body transport (DC-9) and a wide body transport (DC-10) in addition to scale model test data. General features of the airframe noise from these aircraft and models are outlined. The results of the assessment of two airframe prediction methods, Fink's and Munson's methods, against flight test data of these aircraft and scale model wind tunnel test data are presented. These methods were extensively evaluated against measured data from several configurations including clean, slat deployed, landing gear-deployed, flap deployed, and landing configurations of both DC-9 and DC-10. They were also assessed against a limited number of configurations of scale models. The evaluation was conducted in terms of overall sound pressure level (OASPL), tone corrected perceived noise level (PNLT), and one-third-octave band sound pressure level (SPL).

  15. Acoustics Noise Test Cell

    Data.gov (United States)

    Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...

  16. Acoustic ambient noise recorder

    Digital Repository Service at National Institute of Oceanography (India)

    Saran, A.K.; Navelkar, G.S.; Almeida, A.M.; More, S.R.; Chodankar, P.V.; Murty, C.S.

    with a robust outfit that can withstand high pressures and chemically corrosion resistant materials. Keeping these considerations in view, a CMOS micro-controller-based marine acoustic ambient noise recorder has been developed with a real time clock...

  17. Low-frequency noise in single electron tunneling transistor

    DEFF Research Database (Denmark)

    Tavkhelidze, A.N.; Mygind, Jesper

    1998-01-01

    The noise in current biased aluminium single electron tunneling (SET) transistors has been investigated in the frequency range of 5 mHz electromagnetic radiation and especially high energy...... of order seconds. In some cases, the positive and negative slopes of the V(Vg) curve have different overlaid noise patterns. For fixed bias on both slopes, we measure the same noise spectrum, and believe that the asymmetric noise is due to dynamic charge trapping near or inside one of the junctions induced...... when ramping the junction voltage. Dynamic trapping may limit the high frequency applications of the SET transistor. Also reported on are the effects of rf irradiation and the dependence of the SET transistor noise on bias voltage. ©1998 American Institute of Physics....

  18. US Navy Submarine Sea Trial of the NASA Air Quality Monitor

    Science.gov (United States)

    Limero, Thomas; Wallace, William T.; Manney, Joshua A.; Mudgett, Paul D.

    2017-01-01

    For the past four years, the Air Quality Monitor (AQM) has been the operational instrument for measuring trace volatile organic compounds on the International Space Station (ISS). The key components of the AQM are the inlet preconcentrator, the gas chromatograph (GC), and the differential mobility spectrometer. Most importantly, the AQM operates at atmospheric pressure and uses air as the GC carrier gas, which translates into a small reliable instrument. Onboard ISS there are two AQMs, with different GC columns that detect and quantify 22 compounds. The AQM data contributes valuable information to the assessment of air quality aboard ISS for each crew increment. The U.S. Navy is looking to update its submarine air monitoring suite of instruments, and the success of the AQM on ISS has led to a jointly planned submarine sea trial of a NASA AQM. In addition to the AQM, the Navy is also interested in the Multi-Gas Monitor (MGM), which was successfully flown on ISS as a technology demonstration to measure major constituent gases (oxygen, carbon dioxide, water vapor, and ammonia). A separate paper will present the MGM sea trial results. A prototype AQM, which is virtually identical to the operational AQM, has been readied for the sea trial. Only one AQM will be deployed during the sea trial, but it is sufficient to detect the compounds of interest to the Navy for the purposes of this trial. A significant benefit of the AQM is that runs can be scripted for pre-determined intervals and no crew intervention is required. The data from the sea trial will be compared to archival samples collected prior to and during the trial period. This paper will give a brief overview of the AQM technology and protocols for the submarine trial. After a quick review of the AQM preparation, the main focus of the paper will be on the results of the submarine trial. Of particular interest will be the comparison of the contaminants found in the ISS and submarine atmospheres, as both represent

  19. Active Noise Control Experiments using Sound Energy Flu

    Science.gov (United States)

    Krause, Uli

    2015-03-01

    This paper reports on the latest results concerning the active noise control approach using net flow of acoustic energy. The test set-up consists of two loudspeakers simulating the engine noise and two smaller loudspeakers which belong to the active noise system. The system is completed by two acceleration sensors and one microphone per loudspeaker. The microphones are located in the near sound field of the loudspeakers. The control algorithm including the update equation of the feed-forward controller is introduced. Numerical simulations are performed with a comparison to a state of the art method minimising the radiated sound power. The proposed approach is experimentally validated.

  20. Ultra-low noise mechanically cooled germanium detector

    Energy Technology Data Exchange (ETDEWEB)

    Barton, P., E-mail: pjbarton@lbl.gov [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Amman, M.; Martin, R. [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Vetter, K. [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Department of Nuclear Engineering, University of California, Berkeley, CA 94720 (United States)

    2016-03-11

    Low capacitance, large volume, high purity germanium (HPGe) radiation detectors have been successfully employed in low-background physics experiments. However, some physical processes may not be detectable with existing detectors whose energy thresholds are limited by electronic noise. In this paper, methods are presented which can lower the electronic noise of these detectors. Through ultra-low vibration mechanical cooling and wire bonding of a CMOS charge sensitive preamplifier to a sub-pF p-type point contact HPGe detector, we demonstrate electronic noise levels below 40 eV-FWHM.

  1. Rapid Submarine Melting Driven by Subglacial Discharge, LeConte Glacier, Alaska

    Science.gov (United States)

    Motyka, R. J.; Dryer, W. P.; Amundson, J. M.; Truffer, M.; Fahnestock, M. A.

    2013-12-01

    Submarine melting impacts the stability of tidewater glaciers worldwide, but the connections between the ocean, a warming climate, and retreat of outlet glaciers are poorly known. Clearly warm seawater plays an important role, but the tremendous heat potential resident in oceans and fjords must first be brought into contact with outlet glacier termini in order to affect them. We show here that for many glaciers, the principal process driving high rates of submarine melting is subglacial discharge of freshwater. This buoyant discharge draws in warm seawater, entraining it in a turbulent upwelling convective flow along the submarine face that melts glacier ice. To capture the effect of changing subglacial discharge on submarine melting, we conducted four days of hydrographic transects during late summer 2012 at LeConte Glacier, Alaska. A major rainstorm allowed us to directly measure the influence of large changes in subglacial discharge. We found strong submarine melt rates that increased from 9.0×1.0 to 16.8×1.3 m/d (ice face equivalent frontal ablation) as subglacial discharge increased from 130 to 440 m^3/s over a four day period. This subglacial discharge drove influx of warm seawater (thermal forcing ~ 8° C) to the terminus with fluxes increasing from 1800 to 4000 m3/s. Our ice equivalent frontal ablation rates due to submarine melting are two to three times values found for Greenland glaciers, where thermal forcing is substantially lower (~ 1 - 4 °C) and termini are wider. Together, these studies confirm the importance of submarine melting at grounded glaciers. At LeConte, the total frontal ablation rate (calving flux plus submarine melting) is ~ 3.0 x10^6 m^3/d w.e., which far surpasses surface ablation. One-half to two-thirds of the frontal ablation during September 2012 can be attributed to submarine melting. A two-layer model driven by a buoyant plume of subglacial discharge has been previously invoked to describe the proglacial fjord circulation

  2. Active noise control primer

    CERN Document Server

    Snyder, Scott D

    2000-01-01

    Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications. The aim of this book is to present all of the basic knowledge one needs for assessing how useful active noise control will be for a given problem and then to provide some guidance for designing, setting up, and tuning an active noise-control system. Written for students who have no prior knowledge of acoustics, signal processing, or noise control but who do have a reasonable grasp of basic physics and mathematics, the book is short and descriptive. It leaves for more advanced texts or research monographs all mathematical details and proofs concerning vibrations, signal processing and the like. The book can thus be used in independent study, in a classroom with laboratories, or in conjunction with a kit for experiment or demonstration. Topics covered include: basic acoustics; human perception and sound; sound intensity...

  3. A particle velocity sensor to measure the sound from a structure in the presence of background noise

    NARCIS (Netherlands)

    de Bree, H.E.; Druyvesteyn, W.F.

    2005-01-01

    The performance (or quality) of a product is often checked by measuring the radiated sound (noise) from the vibrating structure. Often this test has to be done in an environment with background noise, which makes the measurement difficult. When using a (pressure) microphone the background noise can

  4. A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska

    Science.gov (United States)

    Brothers, Daniel; Haeussler, Peter J.; Lee Liberty,; David Finlayson,; Geist, Eric L.; Labay, Keith A.; Michael Byerly,

    2016-01-01

    During the 1964 Great Alaska earthquake (Mw 9.2), several fjords, straits, and bays throughout southern Alaska experienced significant tsunami runup of localized, but unexplained origin. Dangerous Passage is a glacimarine fjord in western Prince William Sound, which experienced a tsunami that devastated the village of Chenega where 23 of 75 inhabitants were lost – the highest relative loss of any community during the earthquake. Previous studies suggested the source of the devastating tsunami was either from a local submarine landslide of unknown origin or from coseismic tectonic displacement. Here we present new observations from high-resolution multibeam bathymetry and seismic reflection surveys conducted in the waters adjacent to the village of Chenega. The seabed morphology and substrate architecture reveal a large submarine landslide complex in water depths of 120–360 m. Analysis of bathymetric change between 1957 and 2014 indicates the upper 20–50 m (∼0.7 km3) of glacimarine sediment was destabilized and evacuated from the steep face of a submerged moraine and an adjacent ∼21 km2 perched sedimentary basin. Once mobilized, landslide debris poured over the steep, 130 m-high face of a deeper moraine and then blanketed the terminal basin (∼465 m water depth) in 11 ± 5 m of sediment. These results, combined with inverse tsunami travel-time modeling, suggest that earthquake- triggered submarine landslides generated the tsunami that struck the village of Chenega roughly 4 min after shaking began. Unlike other tsunamigenic landslides observed in and around Prince William Sound in 1964, the failures in Dangerous Passage are not linked to an active submarine delta. The requisite environmental conditions needed to generate large submarine landslides in glacimarine fjords around the world may be more common than previously thought. 

  5. Boulder emplacement and remobilisation by cyclone and submarine landslide tsunami waves near Suva City, Fiji

    Science.gov (United States)

    Lau, A. Y. Annie; Terry, James P.; Ziegler, Alan; Pratap, Arti; Harris, Daniel

    2018-02-01

    The characteristics of a reef-top boulder field created by a local submarine landslide tsunami are presented for the first time. Our examination of large reef-derived boulders deposited by the 1953 tsunami near Suva City, Fiji, revealed that shorter-than-normal-period tsunami waves generated by submarine landslides can create a boulder field resembling a storm boulder field due to relatively short boulder transport distances. The boulder-inferred 1953 tsunami flow velocity is estimated at over 9 m s- 1 at the reef edge. Subsequent events, for example Cyclone Kina (1993), appear to have remobilised some large boulders. While prior research has demonstrated headward retreat of Suva Canyon in response to the repeated occurrence of earthquakes over the past few millennia, our results highlight the lingering vulnerability of the Fijian coastlines to high-energy waves generated both in the presence (tsunami) and absence (storm) of submarine failures and/or earthquakes. To explain the age discrepancies of U-Th dated coral comprising the deposited boulders, we introduce a conceptual model showing the role of repeated episodes of tsunamigenic submarine landslides in removing reef front sections through collapse. Subsequent high-energy wave events transport boulders from exposed older sections of the reef front onto the reef where they are deposited as 'new' boulders, alongside freshly detached sections of the living reef. In similar situations where anachronistic deposits complicate the deposition signal, age-dating of the coral boulders should not be used as a proxy for determining the timing of the submarine landslides or the tsunamis that generated them.

  6. BATHYMETRIC SOUNDING by REMOTE SENSING Using ELECTROMAGNETIC RADIATION

    Directory of Open Access Journals (Sweden)

    Frank C Lin

    2016-11-01

    Full Text Available We describe a novel modus operandi to survey the ocean floor. We utilize the eruption of submarine volcanoes as a light source. The electromagnetic radiation emitted by such eruptions illuminate the ocean floor and thus provides information about the barythmetric topology, and a geostationary satellite can monitor this. Since the wavelength of the electromagnetic radiation is many orders of magnitude shorter than that of the acoustic wave, finer details of the bathymetric features can be obtained. We show that a topographical representation of the seabed can be derived from the Signal Diagram by a simple transformation (a mirror reflection. In this case the radiation is emitted by water molecules stimulated by the heat of the volcanic eruption, in contradistinction to the case of tsunami radiation, where the water molecules are stimulated by mutual collisions at high speed. We give two examples: Illapel, Chile and Chichi-shima, Japan. We have also shown that water molecules in the ocean, when stimulated by the heat of submarine volcanic eruption, will emit infrared radiation

  7. Noise sensitivity and sleep disturbance

    NARCIS (Netherlands)

    Laszlo, H.E.; Janssen, S.A.; Babisch, W.; Hansell, A.L.

    2012-01-01

    It has been shown that noise induced health effects are strongly related to non-acoustical factors such as noise sensitivity. It is a stable personality trait and it can be conceptualised as a causal pathway confounder and/or effect modifier between noise and health. Furthermore noise sensitivity

  8. Community response to tramway noise

    NARCIS (Netherlands)

    Miedema, H.M.E.; Berg, R. van den

    1988-01-01

    A study concerning tramway noise is described and results are presented. The study consisted of a social survey and a noise measurement program. It appeared that tramway noise does not contribute to the annoyance of the total noise if tramway annoyance is substantially below road traffic annoyance

  9. Shear-wave velocity of slope sediments near Hudson Canyon from analysis of ambient noise

    Science.gov (United States)

    Miller, N. C.; Ten Brink, U. S.; Collins, J. A.; McGuire, J. J.; Flores, C. H.

    2014-12-01

    We present new ambient noise data that help constrain the shear strength of marine sediments on the continental slope north of Hudson Canyon on the U.S. Atlantic margin. Sediment shear strength is a key parameter in models of potentially tsunamigenic, submarine slope failures, but shear strength is difficult to measure in situ and is expected to evolve in time with changes in pore pressure. The ambient noise data were recorded by 11 short-period, ocean-bottom seismometers and hydrophones deployed in a ~1 by 1.5 km array for ~6 months on the continental slope. These high frequency (~0.1 - 50 Hz), narrow-aperture data are expected to record noise propagating as interface waves and/or resonating in the upper ~500 m of sediment. Propagation of interface waves is controlled by the shear-wave velocity of the sediment, which we measure by calculating lag-times in cross-correlations of waveforms recorded by pairs of receivers. These measurements of shear-wave velocity will be used to constrain shear strength. The data also appear to record wind-generated noise resonating in layered sediment. We expect this resonance to also be sensitive to shear-wave velocity, and spectral analysis and modeling of harmonics may provide a second constraint on sediment shear strength. Both the correlogram- and spectral-based measurements can be made using hour- to day-long segments of data, enabling us to constrain temporal evolution of shear-wave velocity and potential forcing mechanisms (e.g., tidal and storm loading and submarine groundwater discharge) through the ~6 month deployment.

  10. Apparent resistivity and spectral induced polarization in the submarine environment

    Directory of Open Access Journals (Sweden)

    HERCULES DE SOUZA

    2001-09-01

    Full Text Available Relatively few investigations have employed electrical methods in the submarine environment, which may be promising for mineral deposits or threatened by environmental problems. We have measured the electric field using both disk and bar electrodes in the sea water at three different levels: sea surface, seven meters deep, and sea bottom at a depth of ten meters, employing a 2 m spacing dipole-dipole array with 7 array spacings of investigation, and 13 values of frequencies at steps of (2N hertz, N = -2, -1, 0, 1, 2,.....10. The measurement allowed the analysis of the electric field as a function of frequency and spacing, and of the spectral induced polarization. Modelling and interpretation of the apparent resistivity yielded a good fit with previous drilling data. Analysis of the spectrum of the complex apparent resistivity and the comparison with equivalent circuits, provided information about the grain size, the mineral composition and the major induced polarization phenomenon occurring below the sea. Therefore the result of the present research show the feasibility of measuring the variation of seawater resistivity in situ, as well as the resistivity of sea bottom sediments.Relativamente poucas investigações têm empregado métodos elétricos no ambiente submarino, o qual pode ser promissor para depósitos minerais ou ameaçado por problemas ambientais. Nós medimos o campo elétrico usando eletrodos em forma de disco e de barra na água do mar, em três níveis distintos: superfície, sete metros de profundidade, e fundo do mar a dez metros de profundidade, empregando um dispositivo dipolo-dipolo com 2m de afastamento, 7 níveis de investigação e 13 valores de freqüência a intervalos de (2N hertz, N = -2, -1, 0, 1, 2, ... 10. A medida permitiu a análise do campo elétrico como uma função de freqüência e afastamento, e da polarização induzida espectral. A modelagem e a interpretação da resistividade aparente se ajustaram bem

  11. Noise in the operating room

    DEFF Research Database (Denmark)

    Hasfeldt-Hansen, Dorthe; Lærkner, Eva Ann; Birkelund, Regner

    2010-01-01

    Because noise is a general stressor, noise in the OR should be avoided whenever possible. This article presents the results of a review of the research literature on the topic of noise in the OR. A systematic literature search was conducted. Eighteen relevant articles were identified...... and categorized as follows: noise levels, noise sources, staff performances, and patient’s perception of noise. Each study was assessed according to the strength of the evidence and the quality of the study. Noise levels in the OR in general exceed recommended levels, and the noise sources are related...... to equipment and staff behavior. The main effect of noise on staff performances is related to impaired communication, resulting in a negative effect on patient safety. The literature on patients’ perception of noise is both limited and inconsistent, and more research on this topic is needed....

  12. Resistive Switching Assisted by Noise

    OpenAIRE

    Patterson, G. A.; Fierens, P. I.; Grosz, D. F.

    2013-01-01

    We extend results by Stotland and Di Ventra on the phenomenon of resistive switching aided by noise. We further the analysis of the mechanism underlying the beneficial role of noise and study the EPIR (Electrical Pulse Induced Resistance) ratio dependence with noise power. In the case of internal noise we find an optimal range where the EPIR ratio is both maximized and independent of the preceding resistive state. However, when external noise is considered no beneficial effect is observed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Doolittle, R.

    1996-01-01

    The state of the art of model development for application to computer studies of undersea search systems utilizing acoustics is surveyed in this document. Due to the demands for surveillance of submarines operating in ocean basins, the development of noise models for application in deep oceans is fairly advanced and somewhat generic. This is due to the deep sound channel, discovered during World War II, which when present allows for long-range sound propagation with little or no interaction with the bottom. Exceptions to this channel, also well understood, are found in both the high latitudes where the sound is upward refracting and in tropical ocean areas with downward refracting sound transmission. The controlling parameter is the sound speed as a function of depth within the ocean, the sound speed profile. When independent of range, this profile may be converted to a noise-versus-depth profile with well-validated consequences for deep-ocean ambient noise. When considering ocean areas of shallow water, the littoral regions, the idea of a genenic ocean channel advisedly is abandoned. The locally unique nature of both the noise production mechanisms and of the channel carrying the sound, obviates the generic treatment. Nevertheless, idealizations of this case exist and promote the understanding if not the exact predictability of the statistics of shallow water ambient noise. Some examples of these models are given in this document.

  14. Extraaural effects of noise

    Energy Technology Data Exchange (ETDEWEB)

    Marth, E.; Gruber, M.; Koeck, M.; Moese, J.R.; Gallasch, E.; Fueger, G.F.

    This study investigates the effects of a short-term exposition (15 sec) to an indifferent, broad spectrum of noise. Noise levels were set at 85 dB(A) and 110 dB(A). Stress mediators and compensatory mechanisms were studied in 30 test persons. The study was particularly concerned with the metabolic processes providing energy for fight or flight reactions. Most importantly triglycerides are hydrolysed in order to be able to produce the fatty acids that are released. This catabolism is a function of an ACTH-activated lipase. In 93% of the person tested, triglycerides decreased by 7 to 40% of the initial concentration. Blood sugar reaction can be described in two phases: Initially, there was a slight increase in the blood sugar concentration; at higher noise levels, it was followed by a slight decrease. This behaviour was even more characteristic of the insulin concentration. At 85 dB(A), no significant difference concentration was found compared with the levels previous to noise exposition. At 110 dB(A), there was a significant decrease in the insulin level. Vaso constriction of the peripheral blood vessels is a useful parameter for the stress caused by noise. This was shown by registering the finger pulse during the test.

  15. Noise and Function

    CERN Document Server

    Weinstein, Steven

    2016-01-01

    Noise is widely understood to be something that interferes with a signal or process. Thus, it is generally thought to be destructive, obscuring signals and interfering with function. However, early in the 20th century, mechanical engineers found that mechanisms inducing additional vibration in mechanical systems could prevent sticking and hysteresis. This so-called "dither" noise was later introduced in an entirely different context at the advent of digital information transmission and recording in the early 1960s. Ironically, the addition of noise allows one to preserve information that would otherwise be lost when the signal or image is digitized. As we shall see, the benefits of added noise in these contexts are closely related to the phenomenon which has come to be known as stochastic resonance, the original version of which appealed to noise to explain how small periodic fluctuations in the eccentricity of the earth's orbit might be amplified in such a way as to bring about the observed periodic transiti...

  16. Airport noise and teratogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Edmonds, L.D.; Layde, P.M.; Erickson, J.D.

    1979-07-01

    It has been suggested that exposure to high-noise levels near major airports may cause increased incidence of birth defects in the offspring of parents residing near these airports. Using data gathered in Metropolitan Atlanta during 1970 to 1972, we compared the rates of seventeen categories of defects in high- and low-noise census tracts. No significant differences were observed. However, when we subdivided the category of central nervous system defects into several subcategories of specific defects, we noted a significantly increased incidence of spina bifida without hydrocephalus in the high-noise areas. Because of the small number of cases associated with this finding we did a matched case-control study using all cases of central nervous system defects born during the years 1968 to 1976. No significantly increased risk for residents in the high-noise areas was noted in this study. It is our opinion that noise or other factors associated with residence near airports are unlikely to be important environmental teratogens.

  17. The Juno Radiation Monitoring (RM) Investigation

    DEFF Research Database (Denmark)

    Becker, H. N.; Alexander, J. W.; Adriani, A.

    2017-01-01

    The Radiation Monitoring Investigation of the Juno Mission will actively retrieve and analyze the noise signatures from penetrating radiation in the images of Juno’s star cameras and science instruments at Jupiter. The investigation’s objective is to profile Jupiter’s > 10-MeV electron environment...

  18. Iterative framework radiation hybrid mapping

    Science.gov (United States)

    Building comprehensive radiation hybrid maps for large sets of markers is a computationally expensive process, since the basic mapping problem is equivalent to the traveling salesman problem. The mapping problem is also susceptible to noise, and as a result, it is often beneficial to remove markers ...

  19. Evaluation of Freshwater Aquatic Resources and Stormwater Management at U.S. Naval Submarine Base, Bangor, Washington

    National Research Council Canada - National Science Library

    May, Christopher

    1997-01-01

    Surface and storm water conditions on the Naval Submarine Base (NSB), Bangor, Washington, are evaluated, and recommendations are made to improve water quality and enhance the ecological integrity of aquatic resources located on the base...

  20. Hydrothermal processes related to some Triassic and Jurassic submarine basaltic complexes in northeastern Hungary, the Dinarides and Hellenides

    National Research Council Canada - National Science Library

    Gabriella B Kiss; Ferenc Molnár; Ladislav A Palinkas

    2016-01-01

      Comparative studies on hydrothermal alteration of submarine peperitic basalt occurrences related to the Triassic early rifting of the Neotethys were carried out in various parts of the Dinarides and Hellenides...

  1. Volume transport data from a submarine cable in the Florida Strait from 1982 to 1998 (NODC Accession 0087879)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Daily mean volume transport data of the Florida Current collected with a submarine cable spanning from South Florida to the Grand Bahama Island in the Florida Strait...

  2. Submarine flow discharge changes as a way to explain incission-overspilling and other cycles in submarine channel sequences

    Science.gov (United States)

    Milana, J. P.; Kneller, B.; Dykstra, M.

    2009-04-01

    -stratification. The second bedform recognized is related to described macrodunes, and is comparable to large-scale antidunes, and produce tabular bodies with very subtle undulating structure. The third and perhaps more important is described as "gravel sheets" although they could be also low-relief gravel dunes developed during low-flow events, on top of the large-scale bedforms or directly over a flat gravelly bed. It is well known that bedforms produce the effect of delay averaged sediment velocity with respect to flow velocity, and thus we propose that this delay has an important geological effect as it creates a lag time between the onset of discharge increase and the time the channel bed reaches an equilibrium with the dominant flows. The effect of changes in the transport efficiency of submarine slope systems in the resulting depositional architecture is already known. However, we introduce here the concept of lagging the coarsest-grained fractions, delayed by the fact they involve in bedform building which move at lower velocities of the flows and hence allow the system to pass along a stage in which flows are big and fast, but the bed is not in equilibrium with them and as a result, canyoning may occur. These changes in external conditions (flow discharge) is likely to occur as a result of changes of turbid water near the slope by fluvial action and hence it would be t result of the interplay of river discharge and eustacy.

  3. Effect of operating conditions on gearbox noise

    Science.gov (United States)

    Oswald, Fred B.; Zakrajsek, James J.; Townsend, Dennis P.; Atherton, William; Lin, Hsiang Hsi

    1992-01-01

    Low contact ratio spur gears were tested in the NASA gear noise rig to study the noise radiated from the top of the gearbox. The measured sound power from the gearbox top was obtained from a near field acoustic intensity scan taken at 63 nodes just above the surface. The sound power was measured at a matrix of 45 operating speeds and torque levels. Results are presented in the form of a spectral speed map and as a plot of sound power versus torque (at constant speed) and as sound power versus speed (at constant torque). Because of the presence of vibration modes, operating speed was found to have more impact on noise generation than torque level. A NASA gear dynamics code was used to compute the gear tooth dynamic overload at the same 45 operating conditions used for the experiment. Similar trends were found between the analytical results for dynamic tooth overload and experimental results for sound power. Dynamic analysis may be used to design high quality gears with profile relief optimized for minimum dynamic load and noise.

  4. Road Traffic Noise

    Science.gov (United States)

    Beckenbauer, Thomas

    Road traffic is the most interfering noise source in developed countries. According to a publication of the European Union (EU) at the end of the twentieth century [1], about 40% of the population in 15 EU member states is exposed to road traffic noise at mean levels exceeding 55 dB(A). Nearly 80 million people, 20% of the population, are exposed to levels exceeding 65 dB(A) during daytime and more than 30% of the population is exposed to levels exceeding 55 dB(A) during night time. Such high noise levels cause health risks and social disorders (aggressiveness, protest, and helplessness), interference of communication and disturbance of sleep; the long- and short-term consequences cause adverse cardiovascular effects, detrimental hormonal responses (stress hormones), and possible disturbance of the human metabolism (nutrition) and the immune system. Even performance at work and school could be impaired.

  5. Noise and Tinnitus

    Directory of Open Access Journals (Sweden)

    Mansoureh Adel Ghahraman

    1999-03-01

    Full Text Available Tinnitus from the Latin word tinnire meaning ringing is the perception of sound within the human ear in the absence of corresponding external sound. The most common cause is noise induced hearing loss. Tinnitus may be induced by an acoustic trauma or a permanent noise in the workplace. In case that Tinnitus is induced by acoustic trauma the site of lesion is commonly the base of the cochlea. Tinnitus in the senile population is mostly accompanying presbycusis. Although the incidence of permanent tinnitus following noise exposure is high, little is published about this issue. In the current article we are aimed at studying the prevalence of tinnitus in Minoo and other manufactures.

  6. Simple models for the simulation of submarine melt for a Greenland glacial system model

    Directory of Open Access Journals (Sweden)

    J. Beckmann

    2018-01-01

    Full Text Available Two hundred marine-terminating Greenland outlet glaciers deliver more than half of the annually accumulated ice into the ocean and have played an important role in the Greenland ice sheet mass loss observed since the mid-1990s. Submarine melt may play a crucial role in the mass balance and position of the grounding line of these outlet glaciers. As the ocean warms, it is expected that submarine melt will increase, potentially driving outlet glaciers retreat and contributing to sea level rise. Projections of the future contribution of outlet glaciers to sea level rise are hampered by the necessity to use models with extremely high resolution of the order of a few hundred meters. That requirement in not only demanded when modeling outlet glaciers as a stand alone model but also when coupling them with high-resolution 3-D ocean models. In addition, fjord bathymetry data are mostly missing or inaccurate (errors of several hundreds of meters, which questions the benefit of using computationally expensive 3-D models for future predictions. Here we propose an alternative approach built on the use of a computationally efficient simple model of submarine melt based on turbulent plume theory. We show that such a simple model is in reasonable agreement with several available modeling studies. We performed a suite of experiments to analyze sensitivity of these simple models to model parameters and climate characteristics. We found that the computationally cheap plume model demonstrates qualitatively similar behavior as 3-D general circulation models. To match results of the 3-D models in a quantitative manner, a scaling factor of the order of 1 is needed for the plume models. We applied this approach to model submarine melt for six representative Greenland glaciers and found that the application of a line plume can produce submarine melt compatible with observational data. Our results show that the line plume model is more appropriate than the cone plume

  7. Changes to United States Navy Submarine Design and Construction during World War I, as Determined by the General Board.

    Science.gov (United States)

    2017-06-09

    and influence of operational doctrine that led to significant innovation during the interwar period. 15. SUBJECT TERMS Anti-Submarine Warfare (ASW...naval technology and influence of operational doctrine that led to significant innovation during the interwar period. v ACKNOWLEDGMENTS Many...Russian government Anti Access and Area Denial programs, it can be seen how submarine design and construction remains as important today as when Germany

  8. TECHNICAL NOTE: Observations on the use of a viscoelastic joint to provide noise reduced sonar domes

    Science.gov (United States)

    House, J. R.

    1997-10-01

    This paper concerns the noise and vibration advantages of an energy absorbing composite joint and its relevance to noise reduced glass reinforced polyester (GRP) sonar domes. Once installed on an operational boat, hydrodynamic flow and supporting structural induced vibrations cause the dome to vibrate, thus radiating noise and interfering with sonar sensor response. The results of a vibration transmissibility study on a GRP - steel interface are discussed as the first step in designing a composite viscoelastic joint that can act as a vibration sink to absorb flow generated and structure borne noise within GRP sonar domes. Preliminary investigations concerning the absorption of compressional waves by use of a tapered viscoelastic interlayer are discussed. It is shown that a tapered viscoelastic interlayer placed between a GRP beam and steel supporting substrate can produce a significant absorption of vibrational energy, reducing water borne radiated noise and providing a significantly quieter noise platform than conventional sonar jointing technology.

  9. Community response to noise

    Directory of Open Access Journals (Sweden)

    Takashi Yano

    2012-01-01

    Full Text Available Activities from 2008 to 2011 by ICBEN community response to noise team were summarized. That is, individual community-based indexes such as community tolerance Level, Zuricher Fluglarm Index (ZFI and Frankfurter Fluglarm Index (FFI/FNI were newly proposed, differences in railway bonus between Europe and Asia were discussed by a Swedish survey, socio-acoustic surveys were reported from developing countries, and annoyance equivalents and dominant source models were proposed as the adequate combined noise model. Furthermore, not only negative, but also positive aspects of sound were discussed as soundscape studies. Finally, seven items were listed as future team activities.

  10. Noise Source Location Optimization

    Directory of Open Access Journals (Sweden)

    Ed O’Keefe

    1994-01-01

    Full Text Available This article describes a method to determine locations of noise sources that minimize modal coupling in complex acoustic volumes. Using the acoustic source scattering capabilities of the boundary element method, predictions are made of mode shape and pressure levels due to various source locations. Combining knowledge of the pressure field with a multivariable function minimization technique, the source location generating minimum pressure levels can be determined. The analysis also allows for an objective comparison of “best/worst” locations. The technique was implemented on a personal computer for the U.S. Space Station, predicting 5–10 dB noise reduction using optimum source locations.

  11. Jet Engine Noise Reduction

    Science.gov (United States)

    2009-04-01

    all of these noise sources. 6 777-200 A330-300 MD-90-30 MD-11 A320-214 747-400 A300-600R 767-300ER 757 -200 MD-87 MD-82 B-747-300 A300B4-620...broadband shock noise; fluidic/particulate injection; flexible filaments (i.e., wires attached to the nozzle or tail cone ); offset nozzles to reduce...the introduction of the turbojet engine powered Boeing 707 beginning in 1958. Following a series of lawsuits in the United States and public outcry

  12. Introductory guide to noise

    CSIR Research Space (South Africa)

    Ferreira, T.M

    1973-01-01

    Full Text Available GepteMehek. WHY IS NOISE SO Our ears are used primarily to communicate with others. to give warning of danger and to absorb sensory pleasures such as from music. The degree of irritation is related to the extent to which a sound interferes with these uses... on aircraft that make too much noise. Motor cars, buses, buzz-bikes and vacuum deaners can be effectively quietened but until now the public has not been prepared to pay the price of legislation. Also, many young sports-car enthusiasts still think...

  13. Validated Design and Analysis Tool for Small Vertical-Lift Unmanned Air Vehicle Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A procedure and supporting computer code for the prediction of noise that radiates from small, vertical lift UAV aircraft is proposed. The resulting building block...

  14. Radiation Therapy

    Science.gov (United States)

    Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them from ... half of all cancer patients receive it. The radiation may be external, from special machines, or internal, ...

  15. Natural and anthropogenic ocean noise recorded at long-term and temporary observatories

    Science.gov (United States)

    Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony B.; Geissler, Wolfram

    2017-04-01

    Most people worldwide would assume that the oceans are silent. However, a number of natural phenomenon's like ocean waves, wind, lightening, ice noise, earthquakes, and submarine volcanic activity contributes to the ambient ocean noise. During their evolution, marine animals like fish and mammals have adopted in many ways to the acoustic properties of the sea. Yet in recent decades, anthropogenic and hence manmade ocean noise level has risen profoundly. Due to extreme reliance of fish and mammals on underwater sounds for basic life functions, including searching for food or mate and the absence of any mechanism to safeguard them against it, underwater noise pollution may disrupt marine life. The primary sources of low-frequency anthropogenic noise include sounds associated with shipping, military operations, oil and gas exploration and production, and even research activities. Some scientists suggest that today virtually no marine environment is without any noise pollution. Thus, all marine life forms that rely heavily on the integrity of their acoustic habitat may have to adapt to new conditions. Of greatest concern for whales are low-frequency sounds that travel long distances in the ocean. Ship propellers and motors, for instance, produce sound at low frequencies, as do natural and manmade seismic activity. These profound, loud noises reverberate in the deep ocean and can effectively mask or block vital whale communication. However, in general very little is known about the world-wide distribution of ambient ocean noise. Thus, on a global scale and considering the vast areas of the world's oceans, we know virtually nothing about noise levels in different parts of the oceans and how anthropogenic noise contributes to ambient noise. Here, we use hydrophone recordings from the UN's Comprehensive Nuclear-Test-Ban Treaty organization (CTBTO) and ocean-bottom seismometers to provide an assessment of noise in all major basins, including the Pacific, Atlantic and Indian

  16. Psychoacoustic study on contribution of fan noise to engine noise

    Science.gov (United States)

    Zhang, Junhong; Liu, Hai; Bi, Fengrong; Ni, Guangjian; Zhang, Guichang; Lin, Jiewei; Yu, Hanzhengnan

    2012-07-01

    There are more researches on engine fan noise control focusing on reducing fan noise level through optimizing fan structure, and a lot of research achievements have been obtained. However, researches on the effect of fan noise to engine noise quality are lacking. The influences of the effects of fan structure optimization on the engine noise quality are unclear. Thus, there will be a decline in fan noise level, but the deterioration of engine noise quality. Aiming at the above problems, in consideration of fan structure design and engine noise quality, an innovative method to analyze the contribution of fan noise to engine noise quality using psychoacoustic theory is proposed. The noises of diesel engine installing different cooling fans are measured by using the acoustic pressure method. The experiment results are regarded as analysis samples. The model of sensory pleasantness is used to analyze the sound quality of a diesel engine with different cooling fans. Results show that after installing 10-blade fan in medium diameter the sensory pleasantness at each test point is increased, and the increase is 13.53% on average, which indicate the improvement of the engine noise quality. In order to verify the psychoacoustical analysis, the subjective assessment is carried out. The test result shows the noise quality of engine installed 10-blade fan in medium diameter is most superior. 1/3 octave frequency spectrum analysis is used to study the reason of the improvement of engine noise quality. It is found that after installing proper cooling fan the sound pressure level below 400 Hz are obviously increased, the frequency assignment and spectral envelope are more reasonable and a proper cooling fan can optimize the spectrum structure of the engine noise. The psychoacoustic study is applied in the contribution of fan noise to engine noise, and the idea of engine sound quality improvement through the structure optimization is proposed.

  17. Radiation dosimetry

    CERN Document Server

    Hine, Gerald J; Hine, Gerald J

    1956-01-01

    Radiation Dosimetry focuses on the advancements, processes, technologies, techniques, and principles involved in radiation dosimetry, including counters and calibration and standardization techniques. The selection first offers information on radiation units and the theory of ionization dosimetry and interaction of radiation with matter. Topics include quantities derivable from roentgens, determination of dose in roentgens, ionization dosimetry of high-energy photons and corpuscular radiations, and heavy charged particles. The text then examines the biological and medical effects of radiation,

  18. Active vibrations and noise control for turboprop application research program activities

    Science.gov (United States)

    Paonessa, A.; Concilio, A.; Lecce, Leonardo V.

    1992-01-01

    The objectives of this work include the following: (1) development of active noise control techniques to alleviate inefficiencies and drawbacks of passive noise control approach especially at low frequencies; (2) reduction of structurally radiated noise applying external forces to the vibrating structure by means of force actuators made of piezoelectric material; and (3) reduction of fuselage vibration levels in propeller driven aircraft by means of distributed piezoelectric actuators that are actively controlled.

  19. CT radiation dose and iterative reconstruction techniques.

    Science.gov (United States)

    Padole, Atul; Ali Khawaja, Ranish Deedar; Kalra, Mannudeep K; Singh, Sarabjeet

    2015-04-01

    1. CT radiation dose optimization is one of the major concerns for the scientific community. 2. CT image quality is dependent on the selected image reconstruction algorithm. 3. Iterative reconstruction algorithms have reemerged with the potential of radiation dose optimization by lowering image noise. 4. Tube current is the most common parameter used to reduce radiation dose along with iterative reconstruction. 5. Tube potential (kV) is also used for dose optimization with iterative reconstruction in CT angiography protocols and small patients.

  20. Playback Experiments for Noise Exposure.

    Science.gov (United States)

    Holles, Sophie; Simpson, Stephen D; Lecchini, David; Radford, Andrew N

    2016-01-01

    Playbacks are a useful tool for conducting well-controlled and replicated experiments on the effects of anthropogenic noise, particularly for repeated exposures. However, playbacks are unlikely to fully reproduce original sources of anthropogenic noise. Here we examined the sound pressure and particle acceleration of boat noise playbacks in a field experiment and reveal that although there remain recognized limitations, the signal-to-noise ratios of boat playbacks to ambient noise do not exceed those of a real boat. The experimental setup tested is therefore of value for use in experiments on the effects of repeated exposure of aquatic animals to boat noise.

  1. Neuroanatomical substrate of noise sensitivity

    DEFF Research Database (Denmark)

    Kliuchko, Marina; Puoliväli, Tuomas; Heinonen-Guzejev, Marja

    2018-01-01

    Recent functional studies suggest that noise sensitivity, a trait describing attitudes towards noise and predicting noise annoyance, is associated with altered processing in the central auditory system. In the present work, we examined whether noise sensitivity could be related to the structural...... and hippocampus was measured as well. According to our findings, noise sensitivity is associated with the grey matter volume in the selected structures. Among those, we propose and discuss particular areas, previously linked to auditory perceptual, emotional and interoceptive processing, in which larger grey...... matter volume seems to be related to higher noise sensitivity....

  2. Low-Noise Operation of All-Fiber Femtosecond Cherenkov Laser

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Villanueva Ibáñez, Guillermo Eduardo; Lægsgaard, Jesper

    2013-01-01

    We investigate the noise properties of a femtosecond all-fiber Cherenkov radiation source with emission wavelength around 600 nm, based on an Yb-fiber laser and a highly-nonlinear photonic crystal fiber. A relative intensity noise as low as - 103 dBc/Hz, corresponding to 2.48 % pulse-to-pulse flu...

  3. Impulse Noise Injury Model.

    Science.gov (United States)

    Chan, Philemon; Ho, Kevin; Ryan, Allen F

    2016-05-01

    The new Auditory 4.0 model has been developed for the assessment of auditory outcomes, expressed as temporary threshold shift (TTS) and permanent threshold shift (PTS), from exposures to impulse noise for unprotected ears, including the prediction of TTS recovery. Auditory 4.0 is an empirical model, constructed from test data collected from chinchillas exposed to impulse noise in the laboratory. Injury outcomes are defined as TTS and PTS, and Auditory 4.0 provides the full range of TTS and PTS dose-response curves with the risk factor constructed from A-weighted sound exposure level. Human data from large weapons noise exposure was also used to guide the development of the recovery model. Guided by data, a 28-dBA shift was applied to the dose-response curves to account for the scaling from chinchillas to humans. Historical data from rifle noise tests were used to validate the dose-response curves. New chinchilla tests were performed to collect recovery data to construct the TTS recovery model. Auditory 4.0 is the only model known to date that provides the full TTS and PTS dose-response curves, including a TTS recovery model. The model shows good agreement with historical data. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

  4. Curing the noise epidemic

    Science.gov (United States)

    Mazer, Susan

    2005-09-01

    The argument is made that design does not stop when the fixed architectural and acoustical components are in place. Spaces live and breathe with the people who reside in them. Research and examples are presented that show that noise, auditory clutter, thrives on itself in hospitals. Application of the Lombard reflex studies fit into the hospital setting, but do not offer solutions as to how one might reduce the impact. In addition, the basis for looking at the noise component as a physical as well cultural dynamic will be addressed. Whether the result of the wrong conversation in the wrong place or the right conversation in an unfortunate place, talk mixed with sounds of technology is shown to cause its own symptoms. From heightened anxiety and stress to medical errors, staff burnout, or HIPAA violations, the case is made that noise is pandemic in hospitals and demands financial and operational investment. An explanation of how to reduce noise by design of the dynamic environment - equipment, technology, staff protocols is also provided.

  5. Wind turbine noise diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Richarz, W. [Aerocoustics Engineering Ltd., Toronto, ON (Canada); Richarz, H.

    2009-07-01

    This presentation proposed a self-consistent model for broad-band noise emitted from modern wind turbines. The simple source model was consistent with the physics of sound generation and considered the unique features of wind turbines. Although the acoustics of wind turbines are similar to those of conventional propellers, the dimensions of wind turbines pose unique challenges in diagnosing noise emission. The general features of the sound field were deduced. Source motion and source directivity appear to be responsible for amplitude variations. The amplitude modulation is likely to make wind-turbine noise more audible, and may be partly responsible for annoyance that has been reported in the literature. Acoustic array data suggests that broad-band noise is emitted predominantly during the downward sweep of each rotor blade. Source motion and source directivity account for the observed pattern. Rotor-tower interaction effects are of lesser importance. Predicted amplitude modulation ranges from 1 dB to 6dB. 2 refs., 9 figs.

  6. Noise: A Health Problem.

    Science.gov (United States)

    Environmental Protection Agency, Washington, DC. Office of Noise Abatement and Control.

    This booklet contains nine sections describing ways in which noise may endanger health and well-being. Secions are included on: (1) hearing loss; (2) heart disease; (3) other reactions by the body; (4) effects on the unborn; (5) special effects on children; (6) intrusion at home and work; (7) sleep disruption; (8) mental and social well-being; and…

  7. Representing distributed cognition in complex systems: how a submarine returns to periscope depth.

    Science.gov (United States)

    Stanton, Neville A

    2014-01-01

    This paper presents the Event Analysis of Systemic Teamwork (EAST) method as a means of modelling distributed cognition in systems. The method comprises three network models (i.e. task, social and information) and their combination. This method was applied to the interactions between the sound room and control room in a submarine, following the activities of returning the submarine to periscope depth. This paper demonstrates three main developments in EAST. First, building the network models directly, without reference to the intervening methods. Second, the application of analysis metrics to all three networks. Third, the combination of the aforementioned networks in different ways to gain a broader understanding of the distributed cognition. Analyses have shown that EAST can be used to gain both qualitative and quantitative insights into distributed cognition. Future research should focus on the analyses of network resilience and modelling alternative versions of a system.

  8. Physical activity aboard nuclear submarines as measured by pedometry. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Bondi, K.R.; Dougherty, J.H.

    1985-05-23

    Activity levels of 44 submarines were monitored before and during a fleet ballistic missile submarine patrol. These levels were determined by use of a pedometer worn on the hip. Readings were obtained daily and recorded in a log as miles walked. Through extensive preliminary testing it was determined that the miles unit was useless, due to variability in the sensitivity of the pedometer pendulum movements and the inability to determine a meaningful stride length . Results for any combination of pedometer/user were, however, repeatable. For lack of a better term, results are reported in miles per day and are as follows: Control = 2.11 + or - 0.32 and Underway = 1.01 + or - 0.27 (P<.05 Student T). This reduction of more than 50% in activity level may in part be responsible for the physical deconditioning observed during the course of a 40-70 day submergence period.

  9. Submarine groundwater discharge into the near-shore zone of the Great Barrier Reef, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Stieglitz, Thomas [Marine Geophysical Laboratory, School of Mathematical and Physical Sciences, James Cook University, Townsville QLD 4811 (Australia) and Australian Institute of Marine Science, Townsville QLD 4810 (Australia)]. E-mail: thomas.stieglitz@jcu.edu.au

    2005-07-01

    Along the tropical coastline of the Great Barrier Reef (GBR) region, little is known to date about submarine groundwater discharge (SGD) into the near-shore ocean. In an oceanographic sense, SGD consists of freshwater flow from land as well as seawater circulated through sediments. Recent radiochemical and geophysical studies, using the tracer {sup 222}Rn and apparent ground conductivity respectively, provide evidence for SGD to occur in a variety of hydrogeological settings. In this paper, a non-quantitative overview of different settings of SGD in the region is presented: (1) recirculation of seawater through animal burrows in mangrove forests, (2) freshwater SGD from unconfined aquifers as a narrow coastal fringe of freshwater along Wet Tropics beaches, (3) SGD from coastal dune systems in form of localised freshwater springs in the intertidal zone, (4) inner-shelf SGD from confined submarine aquifer systems comprised of riverine paleochannels incised into the shelf.

  10. Research on Fairing design and CFD Analysis of Submarine Pipeline Inspection ARV

    Directory of Open Access Journals (Sweden)

    Jin Xiaojian

    2017-01-01

    Full Text Available Along with the fast development of the ocean exploitation, the cost-effective requirement of autonomous & remotely operated vehicle (ARV, which can perform more complicated missions such as the oil exploitation and the inspection of the submarine pipeline is more urgent. The submarine pipeline inspection ARV can help us better understand, protect and efficiently utilize them for human welfare. Fairing design of a new detection ARV are introduced in this paper. In order to select an appropriate thruster that will achieve the required speed of the ARV, the ANSYS-CFX tools are used to predicted the drag force. The CFD results reveal the distribution of velocity and pressure values of the ARV. In order to verify the CFD modeling process, a towed body was developed and analyzed, compared against the corresponding physical test data.

  11. Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

    OpenAIRE

    Hunter, W. R.; Jamieson, A; Huvenne, V. A. I.; Witte, U

    2013-01-01

    The Whittard Canyon is a branching submarine canyon on the Celtic continental margin, which may act as a conduit for sediment and organic matter (OM) transport from the European continental slope to the abyssal sea floor. In situ stable-isotope labelling experiments were conducted in the eastern and western branches of the Whittard Canyon, testing short-term (3–7 days) responses of sediment communities to deposition of nitrogen-rich marine (Thalassiosira weissflogii) and ni...

  12. Submarine groundwater discharge and associated nutrient fluxes to Discovery Bay, Jamaica

    Science.gov (United States)

    Gordon-Smith, D.

    2013-05-01

    Recent studies have suggested that submarine groundwater discharge can be a significant source of terrestrially-derived nutrients to coastal waters as groundwater fluxes may be comparable to surface fluxes, especially where river flow is small or non-existent, and more attention is now being paid to the contribution of groundwater discharge to biogeochemical processes within the coastal zone. Due to the high temporal and spatial variability of groundwater discharge, quantification may be difficult and various methods have been used to estimate fluxes. The submarine groundwater discharge and associated nutrient fluxes to Discovery Bay, a small tropical embayment on the island of Jamaica, were investigated. Fluxes via submarine springs and seepage through bottom sediments were determined from direct flow measurements and chemical analysis of groundwater and coastal waters. The total groundwater discharge into the bay ranged from 13 to 67 x 103 m3 d-1. Discharge from submarine springs accounted for 70% of the total discharge during dry periods and was not affected by seasonal (rainfall-related) changes. After periods of heavy rainfall, seepage rates increased ten-fold and accounted for about 80% of the total discharge. Subterranean mixing of freshwater and marine water resulted in brackish (salinity ≥ 11) spring and seepage water. The nitrogen and phosphorus originating in the groundwater diluted conservatively within the bay and the average groundwater nutrient concentrations, predicted from dilution curves, were 97(±39) μM N and 0.76(±0.55) μM P. The highest nutrient fluxes to the bay (1200 mol N d-1 and 29 mol P d-1) occurred following heavy rainfall in the watershed. An extension of the study utilizing the naturally-occurring tracers Rn and Ra, to verify the groundwater discharge estimates, and the results of preliminary 222Rn surveys within the bay are also discussed.

  13. Undersea Communications Between Submarines and Unmanned Undersea Vehicles in a Command and Control Denied Environment

    Science.gov (United States)

    2015-03-01

    models in the Map Aware Non- Unifonn Automata (MANA) modeling environment. This analysis explores the value of several different UUV characteristics as...configurations for UUV and submarine interaction in a C2DE area using a series of models in the Map Aware Non- Uniform Automata (MANA) modeling environment...Non-Uniform Automata MANA-V Map Aware Non-Uniform Automata -Vector Mbps Mega-bits Per Second MOE Measure of Effectiveness MSE Mean Square Error

  14. Zone Defense -- Anti-Submarine Warfare Strategy in the age of Littoral Warfare

    Science.gov (United States)

    2008-12-01

    systems malfunctioned at critical times and there is one documented case where the torpedoes they fired failed to detonate .9 However, they were still...Argentine submarine.25 While many ships in the U.S. Navy serve as multi-mission platforms, capable of simultaneously executing numerous tasks, the...fashion with the implosion of the Russian economy. Recently, the Russian economy has shown a resurgence and it has coincided with a resurgence in

  15. Insulation coordination for lightning overvoltages on a long HVDC submarine cable

    Energy Technology Data Exchange (ETDEWEB)

    Mader, D.J.

    1993-01-01

    This paper demonstrates by detailed modelling and simulation a statistical approach to determining the lightning-induced overvoltage stresses on the insulation of a 220 km HVDC submarine cable due to lightning strikes to the overhead line, and explores methods of controlling these overvoltages to levels that will allow lightning impulse withstand levels as low as 2.0 per unit of working voltage with an adequate safety margin.

  16. Coastal Karst Aquifers in Mediterranean Regions. 2. A Methodology for Exploring, Exploiting and monitoring Submarine Springs

    OpenAIRE

    Bakalowicz, Michel; Fleury, P.; Jouvencel, Bruno; Promé, Jean-Jacques; Becker, P.; Carlin, Thierry; Dörfliger, Nathalie; Seidel, Jean-Luc; Sergent, Philippe

    2003-01-01

    International audience; In coastal regions, the study of karst aquifers and the ground water resource exploitation require a specific methodology and exploration and monitoring techniques. Two directions are investigated, leading to new technological and methodological developments. The first investigation axis deals with the exploration of fresh water plumes from submarine karst springs. An Autonomous Underwater Vehicle (AUV) is being developed and tested in order to collect all data (salini...

  17. Deformation microstructures and timing of a large submarine landslide drilled offshore Martinique (IODP Exp. 340)

    Science.gov (United States)

    Guyard, H.; Le Friant, A.; Brunet, M.; Boudon, G.; Emmanuel, L.; Caron, B.; Villemant, B.; Feuillet, N.

    2015-12-01

    Flank-instabilities constitute a recurrent process in the long-term evolution of many volcanoes. A very large submarine landslide deposit (~2100 km2, ~300 km3) drilled southwest Martinique island during the IODP Exp. 340 in 2012 is likely associated with one (or more) major volcanic flank collapse of Mount Pelée during the Late Pleistocene. A recent study revealed that this D1/D2 deposit is emergent in its central part, frontally confined, and mainly comprises remobilized seafloor sediments rather than debris avalanche material from the volcanic edifice (Brunet et al., subm). Here, we investigate the sedimentary microstructures and timing of deformation from the central (Hole 1400B, ~37 km from the coastline) and distal (Hole 1399A, ~70 km from the coastline) units of the D1/D2 deposit, in order to better understand the emplacement dynamics of such potentially tsunamigenic submarine landslides. High resolution CT-Scan analyses were continuously performed on more than 300 m of sediment cores, in order to characterize and distinguish the internal architecture and the complex deformation features of the sediments at each drilling site. The establishment of the stratigraphy, based on δ18O measurements and AMS 14C dating, is still in progress and may confirm the possible link between the submarine landslide deposits and the flank collapse scars observed on the subaerial part of Martinique. These new insights into the timing and emplacement processes of this large submarine landslide will have important implications for tsunami hazards. ReferenceBrunet, M., Le Friant, A., Boudon, G., Lafuerza, S., Talling, P., Hornbach, M., Lebas, E., Guyard, H., and IODP Expedition 340 science party, submitted. Composition, geometry and emplacement dynamics of a large volcanic island landslide offshore Martinique: from volcano flank-collapse to seafloor sediment failure? Geochemistry, Geophysics, Geosystems.

  18. Learning from Experience, Volume 3: Lessons from the United Kingdom’s Astute Submarine Program

    Science.gov (United States)

    2011-01-01

    Nuclear Installations Inspectorate NSRP nuclear steam-raising plant PNO Principal Naval Overseer RCNC Royal Corps of Naval Constructors SEPP Submarine...experience. The Royal Corps of Naval Constructors (RCNC)8 and the engineering officers of the Royal Navy supplemented the technical resources at the MOD...shipyard’s Dockside Test Organisation composed of members from the shipyard, the ship crew, and the MOD. They pre- pared the test agenda and acceptance

  19. Onset of submarine debris flow deposition far from original giant landslide.

    Science.gov (United States)

    Talling, P J; Wynn, R B; Masson, D G; Frenz, M; Cronin, B T; Schiebel, R; Akhmetzhanov, A M; Dallmeier-Tiessen, S; Benetti, S; Weaver, P P E; Georgiopoulou, A; Zühlsdorff, C; Amy, L A

    2007-11-22

    Submarine landslides can generate sediment-laden flows whose scale is impressive. Individual flow deposits have been mapped that extend for 1,500 km offshore from northwest Africa. These are the longest run-out sediment density flow deposits yet documented on Earth. This contribution analyses one of these deposits, which contains ten times the mass of sediment transported annually by all of the world's rivers. Understanding how this type of submarine flow evolves is a significant problem, because they are extremely difficult to monitor directly. Previous work has shown how progressive disintegration of landslide blocks can generate debris flow, the deposit of which extends downslope from the original landslide. We provide evidence that submarine flows can produce giant debris flow deposits that start several hundred kilometres from the original landslide, encased within deposits of a more dilute flow type called turbidity current. Very little sediment was deposited across the intervening large expanse of sea floor, where the flow was locally very erosive. Sediment deposition was finally triggered by a remarkably small but abrupt decrease in sea-floor gradient from 0.05 degrees to 0.01 degrees. This debris flow was probably generated by flow transformation from the decelerating turbidity current. The alternative is that non-channelized debris flow left almost no trace of its passage across one hundred kilometres of flat (0.2 degrees to 0.05 degrees) sea floor. Our work shows that initially well-mixed and highly erosive submarine flows can produce extensive debris flow deposits beyond subtle slope breaks located far out in the deep ocean.

  20. The Dragonian Subsurface Abyss and Submarine Force’s Ability to Counter the Rising Threat

    Science.gov (United States)

    2013-05-23

    36Desmond Ball , Trends in Military Acquisitions in the Asia-Pacific Region : Implications for Security and Prospects for Constraints and Controls...accessed January 24, 2013). 53IHS Jane’s, "Enter the Dragon : Inside China’s New Model Navy," Jane’s Navy International, April 20, 2011. https...99s-overhyped-submarine-threat/ (accessed November 7, 2011). Ball , Desmond. Trends in Military Acquisitions in the Asia-Pacific Region : Implications

  1. Variation of aircraft noise annoyance

    Science.gov (United States)

    Dempsey, T. K.

    1980-01-01

    Laboratory and field studies were conducted to determine the basis for increased sensitivity of people to noise during aircraft noise studies. This change in sensitivity could be attributed to either a physiological time-of-day effect (i.e., a circadian rhythm) or simply to the total number of aircraft noise events experienced during a laboratory test period. In order to investigate the time-of-day factor, noise sensitivity measures were obtained from subjects at home with cassette tape recorders/headsets over a 24 hour period. The effect of number of aircraft noise events on noise sensitivity was investigated within a laboratory. In these tests, measures of sensitivity to noise were obtained from subjects before and after their exposure to varying numbers of aircraft noise events. The 24 hour data showed no evidence that noise sensitivity is physiologically cyclical. Consequently, these data can not explain annoyance response variation to aircraft noise tests conducted during the daytime. However, the number of aircraft noise events did influence the subject's noise sensitivity. This effect completely accounts for the systematic increase in noise sensitivity during a laboratory test period.

  2. Noise management by molecular networks.

    Directory of Open Access Journals (Sweden)

    Frank J Bruggeman

    2009-09-01

    Full Text Available Fluctuations in the copy number of key regulatory macromolecules ("noise" may cause physiological heterogeneity in populations of (isogenic cells. The kinetics of processes and their wiring in molecular networks can modulate this molecular noise. Here we present a theoretical framework to study the principles of noise management by the molecular networks in living cells. The theory makes use of the natural, hierarchical organization of those networks and makes their noise management more understandable in terms of network structure. Principles governing noise management by ultrasensitive systems, signaling cascades, gene networks and feedback circuitry are discovered using this approach. For a few frequently occurring network motifs we show how they manage noise. We derive simple and intuitive equations for noise in molecule copy numbers as a determinant of physiological heterogeneity. We show how noise levels and signal sensitivity can be set independently in molecular networks, but often changes in signal sensitivity affect noise propagation. Using theory and simulations, we show that negative feedback can both enhance and reduce noise. We identify a trade-off; noise reduction in one molecular intermediate by negative feedback is at the expense of increased noise in the levels of other molecules along the feedback loop. The reactants of the processes that are strongly (cooperatively regulated, so as to allow for negative feedback with a high strength, will display enhanced noise.

  3. Evaluating noise abatement measures using strategic noise maps

    NARCIS (Netherlands)

    Borst, H.C.; Miedema, H.M.E.; Laan, W.P.N. van der; Lohman, W.J.A.

    2006-01-01

    Noise annoyance due to transportation is widespread in industrialized countries and in urban areas in the developing countries. The European Noise Directive (END) requires an assessment of the noise situation as well as the formulation of action plans for the reduction of the number of people

  4. Rating environmental noise on the basis of noise maps

    NARCIS (Netherlands)

    Miedema, H.M.E.; Borst, H.C.

    2006-01-01

    A system that rates noise on the basis of noise maps has been developed which is based on empirical exposure-response relationships, so that effects in the community will be lower if the system gives a better rating. It is consistent with noise metrics and effect endpoint chosen in the EU, i.e., it

  5. Noise sensitivity and reactions to noise and other environmental conditions

    NARCIS (Netherlands)

    Miedema, H.M.E.; Vos, H.

    2003-01-01

    This article integrates findings from the literature and new results regarding noise sensitivity. The new results are based on analyses of 28 combined datasets (N=23 038), and separate analyses of a large aircraft noise study (N=10939). Three topics regarding noise sensitivity are discussed, namely,

  6. Annoyance of low frequency noise and traffic noise

    DEFF Research Database (Denmark)

    Mortensen, F.R.; Poulsen, Torben

    2001-01-01

    The annoyance of different low frequency noise sources was determined and compared to the annoyance from traffic noise. Twenty-two subjects participated in laboratory listening tests. The sounds were presented by loudspeakers in a listening room and the spectra of the low frequency noises were...

  7. Annoyance of low frequency noise and traffic noise

    DEFF Research Database (Denmark)

    Mortensen, Frank Rysgaard; Poulsen, Torben

    2000-01-01

    The annoyance of different low frequency noise sources was determined and compared to the annoyance from traffic noise. Twenty-two test subjects participated in laboratory listening tests. The sounds were presented by loudspeakers in a listening room and the spectra of the low frequency noises were...

  8. Wide Band CMOS Low-Noise Amplifier Exploiting Noise Cancellation

    NARCIS (Netherlands)

    Bruccoleri, F.; Klumperink, Eric A.M.; Nauta, Bram

    Well-known elementary wide band amplifiers suffer from a fundamental trade-off between noise factor and source impedance matching, which limits their noise figure (NF) to values typically above 3dB. Negative feedback can be employed to break this trade-off, thus allowing lower noise figures,

  9. Reducing Environmental Noise Impacts: A USAREUR Noise Management Program Handbook

    Science.gov (United States)

    1991-06-01

    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

  10. Navigation and history of science: autopsy to submarine Kursk. Survival previsions were not sufficient

    Directory of Open Access Journals (Sweden)

    Ignacio Jáuregui-Lobera

    2018-01-01

    Full Text Available On August 12, 2000, Saturday, a Russian submarine of the Oscar II class, the K-141 Kursk, sank in the Barents Sea, while sailing as part of the "Summer-X Exercise" manoeuvres. The Kursk was a giant double-hulled submarine, with nine sealed compartments, considered impossible to be sunk. During the manoeuvres, at 08:51 local time, the Kursk requested permission to prepare a torpedo and it received the response "Dobro" (good in English. At 11:29:34 (07:29:50 UTC the Norwegian seismic monitoring network (NORSAR registered an earthquake of intensity 1.5 on the Richter scale at northeast of Murmansk, approximately 250 Km from Norway, and 80 Km from the Kola Peninsula. At 11:31:48, two minutes and fourteen seconds later, a second movement, 4.2 on the Richter scale and 250 times longer than the first, was recorded by different seismographs, even being detected in Alaska. It was equivalent to an explosion of 2-3 Tm of TNT. After a great confusion and propaganda, there was no choice other than to accept the facts: the Kursk had suffered two explosions, had sunk and the whole crew had perished. But what happened in that submarine? It seems clear that survival previsions were not sufficient.

  11. Aerobic performance of Special Operations Forces personnel after a prolonged submarine deployment.

    Science.gov (United States)

    Fothergill, D M; Sims, J R

    2000-10-01

    The US Navy's Sea, Air and Land Special Operations Forces personnel (SEALs) perform a physically demanding job that requires them to maintain fitness levels equivalent to elite athletes. As some missions require SEALs to be deployed aboard submarines for extended periods of time, the prolonged confinement could lead to deconditioning and impaired mission-related performance. The objective of this field study was to quantify changes in aerobic performance of SEAL personnel following a 33-day submarine deployment. Two age-matched groups of SEALs, a non-deployed SEAL team (NDST, n = 9) and a deployed SEAL team (DST, n = 10), performed two 12-min runs for distance (Cooper tests) 5 days apart pre-deployment and one Cooper test post-deployment. Subjects wore a Polar Vantage NVTM heart rate (HR) monitor during the tests to record exercise and recovery HR. Variables calculated from the HR profiles included mean exercise heart rate (HRmean), maximum exercise heart rate (HRmax), the initial slope of the HR recovery curve (HRrecslope) and HR recovery time (HRrectime). The second pre-deployment test (which was used in the comparison with the post-deployment test) showed a 2% mean increase in the distance achieved compared with the first (n = 18, p submarine compromises the aerobic performance of SEAL personnel. The resulting deconditioning could influence mission success.

  12. River and Submarine Groundwater Discharge Effects on Diatom Phytoplankton Abundance in the Gulf of Alaska

    Directory of Open Access Journals (Sweden)

    Alanna L. Lecher

    2017-12-01

    Full Text Available The Gulf of Alaska is a highly productive ecosystem that supports fisheries and subsistence harvesting of marine resources. The highly productive summer season begins with a bloom that is dominated by diatoms. Both river and submarine groundwater discharge have been recognized as substantial terrestrial nutrient (nitrate and silicate sources to the Gulf’s coastal waters. Here, the response of in-situ phytoplankton to groundwater and river water additions was evaluated via a bioassay incubation experiment. Special attention was given to diatom genera, as previous studies have shown that submarine groundwater discharge preferentially induces growth of diatoms. The abundance of Pseudo-nitzschia spp., Chaetoceros spp., and Leptocylindrus spp. increased significantly in groundwater and river water containing treatments. Although groundwater and river water are both rich in nitrate and silicate, groundwater treatments with a higher salinity favored a higher relative abundance of Pseudo-nitzschia spp. Conversely, in the highest river water concentration treatments with lower salinity, relative abundances of Pseudo-nitzschia spp. decreased, while Chaetoceros spp. and Leptocylindrus spp. increased. Total abundances of all three genera increased in the lower salinity treatments. These findings could portend changes in the phytoplankton community composition in the Gulf of Alaska as the climate warms and river discharge increases in the coming decades. Furthermore, the findings support previous assertions that submarine groundwater discharge, with higher salinity than river water, is a preferable source of nutrients to the genus Pseudo-nitzschia.

  13. Anthropogenic impacts on deep submarine canyons of the western Mediterranean Sea

    Science.gov (United States)

    Sanchez-Vidal, A.; Tubau, X.; Llorca, M.; Woodall, L.; Canals, M.; Farré, M.; Barceló, D.; Thompson, R.

    2016-02-01

    Submarine canyons are seafloor geomorphic features connecting the shallow coastal ocean to the deep continental margin and basin. Often considered biodiversity hotspots, submarine canyons have been identified as preferential pathways for water, sediment, pollutant and litter transfers from the coastal to the deep ocean. Here we provide insights on the presence of some of the most insidious man-made debris and substances in submarine canyons of the western Mediterranean Sea, which are relevant to achieve a "Good Environmental Status" by 2020 as outlined in the European Union's ambitious Marine Strategy Framework Directive. Ranked by size on a decreasing basis, we review the origin, distribution and transport mechanisms of i) marine litter, including plastic, lost fishing gear and metallic objects; ii) microplastics in the form of fibers of rayon, polyester, polyamide and acetates; and iii) persistent organic pollutants including the toxic and persistent perfluoroalkyl substances. This integrated analysis allows us to understand the pivotal role of atmospheric driven oceanographic processes occurring in Mediterranean deep canyons (dense shelf water cascading, coastal storms) in spreading any type of man-made compound to the deep sea, where they sink and accumulate before getting buried.

  14. Turbidity Currents, Submarine Landslides and the 2006 Pingtung Earthquake off SW Taiwan

    Directory of Open Access Journals (Sweden)

    Shu-Kun Hsu

    2008-01-01

    Full Text Available Submarine landslides or slumps may generate turbidity currents consisting of mixture of sediment and water. Large and fast-moving turbidity currents can incise and erode continental margins and cause damage to artificial structures such as telecommunication cables on the seafloor. In this study, we report that eleven submarine cables across the Kaoping canyon and Manila trench were broken in sequence from 1500 to 4000 m deep, as a consequence of submarine landslides and turbidity currents associated with the 2006 Pingtung earthquakes offshore SW Taiwan. We have established a full-scale scenario and calculation of the turbidity currents along the Kaoping canyon channel from the middle continental slope to the adjacent deep ocean. Our results show that turbidity current velocities vary downstream ranging from 20 to 3.7 and 5.7 m/s, which demonstrates a positive relationship between turbidity current velocity and bathymetric slope. The violent cable failures happened in this case evidenced the destructive power of the turbidity current to seafloor or underwater facilities that should not be underestimated.

  15. Frontally confined versus frontally emergent submarine landslides: A 3D seismic characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Frey-Martinez, Jose; Cartwright, Joe; James, David [3DLab. School of Earth, Ocean and Planetary Sciences, Cardiff University, P.O. Box 914, Cardiff CF10 3YE (United Kingdom)

    2006-06-15

    Three-dimensional (3D) seismic data from the continental margin offshore Israel (Eastern Mediterranean) have been used to analyse the compressional structures within the toe regions of two major buried submarine landslides: the ISC and the T20. Both landslides are developed within a Plio-Pleistocene slope succession composed predominately of claystones, limestones and siltstones. The high spatial resolution provided by the seismic data has allowed a detailed analysis of the geometries and deformational structures within the toe regions of the two landslides, and this has been used to develop a mechanical model for their development. Importantly, it has been recognised that submarine landslides may be divided into two main types according to their form of frontal emplacement: frontally confined and frontally emergent. In the former, the landslide undergoes a restricted downslope translation and does not overrun the undeformed downslope strata. In the latter, much larger downslope translation occurs because the landslide is able to ramp up from its original basal shear surface and translate in an unconfined manner over the seafloor. We propose that these two types of submarine landslides are end members of a continuum of gravity-driven slope failure processes, which extends from landslides where the headscarp is completely evacuated, to landslides where the material remains entirely within the headscarp. The differentiation of these two end members is of critical importance as their respective mechanisms of formation, downslope propagation and emplacement are significantly different, and hence need to be taken into consideration when analysing their respective kinematics. (author)

  16. Radiation Hardening of Silicon Detectors

    CERN Multimedia

    Leroy, C; Glaser, M

    2002-01-01

    %RD48 %title\\\\ \\\\Silicon detectors will be widely used in experiments at the CERN Large Hadron Collider where high radiation levels will cause significant bulk damage. In addition to increased leakage current and charge collection losses worsening the signal to noise, the induced radiation damage changes the effective doping concentration and represents the limiting factor to long term operation of silicon detectors. The objectives are to develop radiation hard silicon detectors that can operate beyond the limits of the present devices and that ensure guaranteed operation for the whole lifetime of the LHC experimental programme. Radiation induced defect modelling and experimental results show that the silicon radiation hardness depends on the atomic impurities present in the initial monocrystalline material.\\\\ \\\\ Float zone (FZ) silicon materials with addition of oxygen, carbon, nitrogen, germanium and tin were produced as well as epitaxial silicon materials with epilayers up to 200 $\\mu$m thickness. Their im...

  17. Low frequency noise in resonant Josephson soliton oscillators

    DEFF Research Database (Denmark)

    Hansen, Jørn Bindslev; Holst, T.; Wellstood, Frederick C.

    1991-01-01

    to the Nyquist voltage noise in a resistance equal to the dynamic resistance RD of the current-voltage characteristic of the bias point. In contrast, measurements of the linewidth of the microwave radiation from the same JTL showed that the spectral density of the underlying noise voltage scaled as R D2/RS where......The noise in the resonant soliton mode of long and narrow Josephson tunnel junctions (Josephson transmission lines or JTLs) have been measured in the frequency range from 0.1 Hz to 25 kHz by means of a DC SQUID. The measured white noise was found, to within a factor of two, to be equal...... RS is the static resistance. The origin of the different behavior is not known...

  18. Acoustic noise reduction in a 4 T MRI scanner.

    Science.gov (United States)

    Mechefske, Chris K; Geris, Ryan; Gati, Joseph S; Rutt, Brian K

    2002-01-01

    High-field, high-speed magnetic resonance imaging (MRI) can generate high levels of noise. There is ongoing concern in the medical and imaging research communities regarding the detrimental effects of high acoustic levels on auditory function, patient anxiety, verbal communication between patients and health care workers and ultimately MR image quality. In order to effectively suppress the noise levels inside MRI scanners, the sound field needs to be accurately measured and characterized. This paper presents the results of measurements of the sound radiation from a gradient coil cylinder within a 4 T MRI scanner under a variety of conditions. These measurement results show: (1) that noise levels can be significantly reduced through the use of an appropriately designed passive acoustic liner; and (2) the true noise levels that are experienced by patients during echo planar imaging.

  19. Acquired Resistance to Impulse Noise

    National Research Council Canada - National Science Library

    Henderson, Donald

    1997-01-01

    Previous experiments have shown that the mammalians auditory system can be made more resistant to the traumatic effects of noise exposure by having the subject exposed to a lower level, prophylactic noise...

  20. Noise sensitivity and hearing disability

    National Research Council Canada - National Science Library

    Marja Heinonen-Guzejev; Tapani Jauhiainen; Heikki Vuorinen; Anne Viljanen; Taina Rantanen; Markku Koskenvuo; Kauko Heikkilä; Helena Mussalo-Rauhamaa; Jaakko Kaprio

    2011-01-01

    The aim of this study was to investigate the association of noise sensitivity with self-reported hearing disability and hearing levels, with consideration of the role of self-reported history of noise...

  1. Mobile Communication Devices, Ambient Noise, and Acoustic Voice Measures.

    Science.gov (United States)

    Maryn, Youri; Ysenbaert, Femke; Zarowski, Andrzej; Vanspauwen, Robby

    2017-03-01

    The ability to move with mobile communication devices (MCDs; ie, smartphones and tablet computers) may induce differences in microphone-to-mouth positioning and use in noise-packed environments, and thus influence reliability of acoustic voice measurements. This study investigated differences in various acoustic voice measures between six recording equipments in backgrounds with low and increasing noise levels. One chain of continuous speech and sustained vowel from 50 subjects with voice disorders (all separated by silence intervals) was radiated and re-recorded in an anechoic chamber with five MCDs and one high-quality recording system. These recordings were acquired in one condition without ambient noise and in four conditions with increased ambient noise. A total of 10 acoustic voice markers were obtained in the program Praat. Differences between MCDs and noise condition were assessed with Friedman repeated-measures test and posthoc Wilcoxon signed-rank tests, both for related samples, after Bonferroni correction. (1) Except median fundamental frequency and seven nonsignificant differences, MCD samples have significantly higher acoustic markers than clinical reference samples in minimal environmental noise. (2) Except median fundamental frequency, jitter local, and jitter rap, all acoustic measures on samples recorded with the reference system experienced significant influence from room noise levels. Fundamental frequency is resistant to recording system, environmental noise, and their combination. All other measures, however, were impacted by both recording system and noise condition, and especially by their combination, often already in the reference/baseline condition without added ambient noise. Caution is therefore warranted regarding implementation of MCDs as clinical recording tools, particularly when applied for treatment outcomes assessments. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  2. The Signal Importance of Noise

    Science.gov (United States)

    Macy, Michael; Tsvetkova, Milena

    2015-01-01

    Noise is widely regarded as a residual category--the unexplained variance in a linear model or the random disturbance of a predictable pattern. Accordingly, formal models often impose the simplifying assumption that the world is noise-free and social dynamics are deterministic. Where noise is assigned causal importance, it is often assumed to be a…

  3. Weak localization of photon noise

    NARCIS (Netherlands)

    Scalia, Paolo S.; Muskens, Otto L.; Lagendijk, Aart

    2013-01-01

    We present an experimental study of coherent backscattering (CBS) of photon noise from multiple scattering media. We use a pseudothermal light source with a microsecond coherence time to produce a noise spectrum covering a continuous transition, from wave fluctuations to shot noise over several MHz.

  4. Noise mapping inside a car

    Science.gov (United States)

    Strekalov, V. A.; Shaimuhametov, R. R.

    2017-09-01

    We present new wireless sensor telemetry system designed to be mounted on different nodes of the car and record acoustic noises. The proposed system is mapping noise inside a car. The noise field is recorded at the ten control regions simultaneously.

  5. Using multiple geochemical tracers to characterize the hydrogeology of the submarine spring off Crescent Beach, Florida

    Science.gov (United States)

    Swarzenski, P.W.; Reich, C.D.; Spechler, R.M.; Kindinger, J.L.; Moore, W.S.

    2001-01-01

    A spectacular submarine spring is located about 4 km east of Crescent Beach, FL, in the Atlantic Ocean. The single vent feature of Crescent Beach Spring provides a unique opportunity to examine onshore-offshore hydrogeologic processes, as well as point source submarine ground water discharge. The Floridan aquifer system in northeastern Florida consists of Tertiary interspersed limestone and dolomite strata. Impermeable beds confine the water-bearing zones under artesian pressure. Miocene and younger confining strata have been eroded away at the vent feature, enabling direct hydrologic communication of Eocene ground water with coastal bottom waters. The spring water had a salinity of 6.02, which was immediately diluted by ambient seawater during advection/mixing. The concentration of major solutes in spring water and onshore well waters confirm a generalized easterly flow direction of artesian ground water. Nutrient concentrations were generally low in the reducing vent samples, and the majority of the total nitrogen species existed as NH3. The submarine ground water tracers, Rn-222 (1174 dpm I-1, dpm), methane (232 nM) and barium (294.5 nM) were all highly enriched in the spring water relative to ambient seawater. The concentrations of the reverse redox elements U, V and Mo were expectedly low in the submarine waters. The strontium isotope ratio of the vent water (87Sr/86Sr = 0.70798) suggests that the spring water contain an integrated signature indicative of Floridan aquifer system ground water. Additional Sr isotopic ratios from a series of surficial and Lower Floridan well samples suggest dynamic ground water mixing, and do not provide clear evidence for a single hydrogeologic water source at the spring vent. In this karst-dominated aquifer, such energetic mixing at the vent feature is expected, and would be facilitated by conduit and fractured flow. Radium isotope activities were utilized to estimate flow-path trajectories and to provide information on

  6. Estimation of signal and noise for a whole-body photon counting research CT system.

    Science.gov (United States)

    Li, Zhoubo; Leng, Shuai; Yu, Zhicong; Kappler, Stephen; McCollough, Cynthia H

    2016-02-01

    Photon-counting CT (PCCT) may yield potential value for many clinical applications due to its relative immunity to electronic noise, increased geometric efficiency relative to current scintillating detectors, and the ability to resolve energy information about the detected photons. However, there are a large number of parameters that require optimization, particularly the energy thresholds configurations. Fast and accurate estimation of signal and noise in PCCT can benefit the optimization of acquisition parameters for specific diagnostic tasks. Based on the acquisition parameters and detector response of our research PCCT system, we derived mathematical models for both signal and noise. The signal model took the tube spectrum, beam filtration, object attenuation, water beam hardening, and detector response into account. The noise model considered the relationship between noise and radiation dose, as well as the propagation of noise as threshold data are subtracted to yield energy bin data. To determine the absolute noise value, a noise look-up table (LUT) was acquired using a limited number of calibration scans. The noise estimation algorithm then used the noise LUT to estimate noise for scans with a variety of combination of energy thresholds, dose levels, and object attenuation. Validation of the estimation algorithms was performed on our whole-body research PCCT system using semi-anthropomorphic water phantoms and solutions of calcium and iodine. The algorithms achieved accurate estimation of signal and noise for a variety of scanning parameter combinations. The proposed method can be used to optimize energy thresholds configuration for many clinical applications of PCCT.

  7. Adaptive Control of Sound Radiation from a Plate into an Acoustic Cavity Using Active Piezoelectric-Damping Composites

    National Research Council Canada - National Science Library

    Poh, S

    1999-01-01

    ... and noise control systems. The evaluation process will involve monitoring the vibration and noise radiation of these systems using a scanning laser vibrometer system to be acquired through this DURIP program...

  8. Noise and mental performance: personality attributes and noise sensitivity.

    Science.gov (United States)

    Belojevic, G; Jakovljevic, B; Slepcevic, V

    2003-01-01

    The contradictory and confusing results in noise research on humans may partly be due to individual differences between the subjects participating in different studies. This review is based on a twelve year research on the role of neuroticism, extroversion and subjective noise sensitivity during mental work in noisy environment. Neurotic persons might show enhanced "arousability" i.e. their arousal level increases more in stress. Additional unfavorable factors for neurotics are worrying and anxiety, which might prevent them coping successfully with noise, or some other stressors during mental performance. In numerous experiments introverts have showed higher sensitivity to noise during mental performance compared to extroverts, while extroverts often cope with a boring task even by requesting short periods of noise during performance. Correlation analyses have regularly revealed a highly significant negative relation between extroversion and noise annoyance during mental processing. Numerous studies have shown that people with high noise sensitivity may be prevented from achieving the same work results as other people in noisy environment, thus leading to psychosomatic, neurotic or other difficulties. Positive relation between noise annoyance and subjective noise sensitivity might be very strong. Our results have shown, after matching with the results of other relevant studies, that more stable personality, with extroversive tendencies and with a relatively lower subjective noise sensitivity measured with standard questionnaires, may be expected to better adapt to noise during mental performance, compared to people with opposite personality traits.

  9. Noise source separation of diesel engine by combining binaural sound localization method and blind source separation method

    Science.gov (United States)

    Yao, Jiachi; Xiang, Yang; Qian, Sichong; Li, Shengyang; Wu, Shaowei

    2017-11-01

    In order to separate and identify the combustion noise and the piston slap noise of a diesel engine, a noise source separation and identification method that combines a binaural sound localization method and blind source separation method is proposed. During a diesel engine noise and vibration test, because a diesel engine has many complex noise sources, a lead covering method was carried out on a diesel engine to isolate other interference noise from the No. 1-5 cylinders. Only the No. 6 cylinder parts were left bare. Two microphones that simulated the human ears were utilized to measure the radiated noise signals 1 m away from the diesel engine. First, a binaural sound localization method was adopted to separate the noise sources that are in different places. Then, for noise sources that are in the same place, a blind source separation method is utilized to further separate and identify the noise sources. Finally, a coherence function method, continuous wavelet time-frequency analysis method, and prior knowledge of the diesel engine are combined to further identify the separation results. The results show that the proposed method can effectively separate and identify the combustion noise and the piston slap noise of a diesel engine. The frequency of the combustion noise and the piston slap noise are respectively concentrated at 4350 Hz and 1988 Hz. Compared with the blind source separation method, the proposed method has superior separation and identification effects, and the separation results have fewer interference components from other noise.

  10. Discovery of Naturally Etched Fission Tracks and Alpha-Recoil Tracks in Submarine Glasses: Reevaluation of a Putative Biosignature for Earth and Mars

    Directory of Open Access Journals (Sweden)

    Jason E. French

    2016-01-01

    Full Text Available Over the last two decades, conspicuously “biogenic-looking” corrosion microtextures have been found to occur globally within volcanic glass of the in situ oceanic crust, ophiolites, and greenstone belts dating back to ~3.5 Ga. These so-called “tubular” and “granular” microtextures are widely interpreted to represent bona fide microbial trace fossils; however, possible nonbiological origins for these complex alteration microtextures have yet to be explored. Here, we reevaluate the origin of these enigmatic microtextures from a strictly nonbiological standpoint, using a case study on submarine glasses from the western North Atlantic Ocean (DSDP 418A. By combining petrographic and SEM observations of corrosion microtextures at the glass-palagonite interface, considerations of the tectonic setting, measurement of U and Th concentrations of fresh basaltic glass by ICP-MS, and theoretical modelling of the present-day distribution of radiation damage in basaltic glass caused by radioactive decay of U and Th, we reinterpret these enigmatic microtextures as the end product of the preferential corrosion/dissolution of radiation damage (alpha-recoil tracks and fission tracks in the glass by seawater, possibly combined with pressure solution etch-tunnelling. Our findings have important implications for geomicrobiology, astrobiological exploration of Mars, and understanding of the long-term breakdown of nuclear waste glass.

  11. White noise on bialgebras

    CERN Document Server

    Schürmann, Michael

    1993-01-01

    Stochastic processes with independent increments on a group are generalized to the concept of "white noise" on a Hopf algebra or bialgebra. The main purpose of the book is the characterization of these processes as solutions of quantum stochastic differential equations in the sense of R.L. Hudsonand K.R. Parthasarathy. The notes are a contribution to quantum probability but they are also related to classical probability, quantum groups, and operator algebras. The Az ma martingales appear as examples of white noise on a Hopf algebra which is a deformation of the Heisenberg group. The book will be of interest to probabilists and quantum probabilists. Specialists in algebraic structures who are curious about the role of their concepts in probablility theory as well as quantum theory may find the book interesting. The reader should havesome knowledge of functional analysis, operator algebras, and probability theory.

  12. Ex / Noise / CERN / Deerhoof

    CERN Multimedia

    CERN, SM18,

    2015-01-01

    Indie rockers Deerhoof battled with the noise of CERN’s magnet test facilities on 30 August 2015. The band visited CERN at the invitation of ATLAS physicist James Beacham, whose pilot project Ex/Noise/CERN collides experimental music artists with experimental particle physics. Credits: -Producer- CERN Video Productions James Beacham François Briard -Director- Noemi Caraban -Camera- Yann Krajewski Piotr Traczyk Noemi Caraban -Crane operator- Antonio Henrique Jorge-Costa -Live recording at CERN- Mixing at Rec studio/Geneva By Serge Morattel -Infography- Daniel Dominguez Noemi Caraban -Deerhoof- John Dieterich Satomi Matsuzaki Ed Rodriguez Greg Saunier w/Deron Pulley SPECIAL THANKS TO: Michal Strychalski Marta Bajko Maryline Charrondiere Luca Bottura Christian Giloux Rodrigue Faes Mariane Catallon Georgina Hobgen Hailey Reissman Marine Bass

  13. Noise Analysis of MAIA System and Possible Noise Suppression

    Directory of Open Access Journals (Sweden)

    J. Svihlik

    2011-04-01

    Full Text Available This paper is devoted to the noise analysis and noise suppression in a system for double station observation of the meteors now known as MAIA (Meteor Automatic Imager and Analyzer. The noise analysis is based on acquisition of testing video sequences in different light conditions and their further statistical evaluation. The main goal is to find a suitable noise model and subsequently determine if the noise is signal dependent or not. Noise and image model in the wavelet domain should be based on Gaussian mixture model (GMM or Generalized Laplacian Model (GLM and the model parameters should be estimated by moment method. Furthermore, noise should be modeled by GMM or GLM also in the space domain. GMM and GLM allow to model various types of probability density functions. Finally the advanced denoising algorithm using Bayesian estimator is applied and its performance is verified.

  14. Noise Phobia in Dog

    Directory of Open Access Journals (Sweden)

    Mangle

    Full Text Available Fear of thunderstorms and other forms of noise phobia are common problems in dogs. Administering medications along with changing the pet’s environment, and using behavior modification techniques can help ease the fear. Above all, do not give your pet any attention or reward when he is showing signs of fear; this will only reinforce the fearful behavior. [Veterinary World 2008; 1(11.000: 351-352

  15. Tinnitus and leisure noise.

    Science.gov (United States)

    Williams, Warwick; Carter, Lyndal

    2017-04-01

    To study the relationship of life-time noise exposure and experience of tinnitus. Audiometric measures included otoscopy, pure tone air- and bone-conduction hearing threshold levels (HTL) and otoacoustic emissions (OAEs). Participants completed questionnaires including demographic information, past hearing health, history of participation in loud leisure activities, and attitudes to noise. A representative sample (1435) of the young (11-35 years old) Australian population. Of the sample, 63% indicated they experienced tinnitus in some form. There was no correlation of tinnitus experience with HTL or OAE amplitudes. Although median octave band HTLs for those who experienced tinnitus "all the time" were slightly higher for those who did not, neither group exhibited HTLs outside clinically-normal values. Of those who experienced tinnitus a direct correlation was found between frequency of experience of tinnitus and increasing cumulative, life-time noise exposure. Those who experienced tinnitus were more likely to report noticing deterioration in their hearing ability over time and to report difficulty hearing in quiet and/or noisy situations. Experience of tinnitus was found throughout this young population but not associated with HTLs or variation in OAE amplitudes. Males experienced 'permanent' tinnitus at significantly greater rate than females.

  16. Shear-wave velocity of marine sediments offshore Taiwan using ambient seismic noise

    Science.gov (United States)

    Lin, Yu-Tse; Lin, Jing-Yi; Kuo-Chen, Hao; Yeh, Yi-Chin; Cheng, Win-Bin

    2017-04-01

    Seismic ambient noise technology has many advantages over the traditional two-station method. The most important one is that noise is happening all the time and it can be widely and evenly distributed. Thus, the Green's Function of any station pair can be obtained through the data cross-correlation process. Many related studies have been performed to estimate the velocity structures based on the inland area. Only a few studies were reported for the marine area due to the relatively shorter recording time of ocean bottom seismometers (OBS) deployment and the high cost of the marine experiment. However, the understanding about the shear-wave velocity (Vs) of the marine sediments is very crucial for the hazard assessment related to submarine landslides, particularly with the growing of submarine resources exploration. In this study, we applied the ambient noise technique to four OBS seismic networks located offshore Taiwan in the aim of getting more information about the noise sources and having the preliminary estimation for the Vs of the marine sediments. Two of the seismic networks were deployed in the NE part of Taiwan, near the Ryukyu subduction system, whereas the others were in the SW area, on the continental margin rich in gas hydrate. Generally, ambient seismic noise could be associated with wind, ocean waves, rock fracturing and anthropogenic activity. In the southwestern Taiwan, the cross-correlation function obtained from two seismic networks indicate similar direction, suggestion that the source from the south part of the network could be the origin of the noise. However, the two networks in the northeastern Taiwan show various source direction, which could be caused by the abrupt change of bathymetry or the volcanic degassing effect frequently observed by the marine geophysical method in the area. The Vs determined from the dispersion curve shows a relatively higher value for the networks in the Okinawa Trough (OT) off NE Taiwan than that in the

  17. Economical noise- and heat insulation

    Energy Technology Data Exchange (ETDEWEB)

    1982-06-01

    All noise protection and heat insulations measures are interlinked. While noise abatement and insulation is primarily a task of health protection, the economically optimised heat insulation is rather a problem for financial mathematics. Parameters, influencing the heat insulation are subject to changes which will affect the profitability of heat insulation measures in turn. Several options for reducing the noise level are described and some standard values for material cost are supplied. Depending on the kind of noise different abatement methods are suitable which require materials with specific properties. Measures for heat insulation are described which to a great extent are identical will noise abatement measures.

  18. Titan Submarine : AUV Design for Cryogenic Extraterrestrial Seas of Hydrocarbons

    Science.gov (United States)

    Lorenz, Ralph D.; Oleson, Steven; Colozza, Tony; Hartwig, Jason; Schmitz, Paul; Landis, Geoff; Paul, Michael; Walsh, Justin

    2016-04-01

    Saturn's moon Titan has three seas, apparently composed predominantly of liquid methane, near its north pole. The largest of these, Ligeia Mare and Kraken Mare, span about 400km and 1000km respectively, and are linked by a narrow strait. Radar measurements from the Cassini spacecraft (currently in orbit around Saturn) show that Ligeia at least is 160m deep, Kraken perhaps deeper. Titan has a nitrogen atmosphere somewhat denser than Earth's, and gravity about the same as the Earth's moon, and its surface temperature is about 92K ; the seas are liquid under conditions rather similar to those of liquified natural gas (LNG) a commodity with familiar engineering properties. We report a NASA Innovative Advanced Concepts (NIAC) study into a submersible vehicle able to explore these seas, to survey shoreline geomorphology, investigate air-sea exchange processes, measure composition to evaluate stratification and mixing, and map the seabed. The Titan environment poses unique thermal management and buoyancy control challenges (the temperature-dependent solubility of nitrogen in methane leads to the requirement to isolate displacement gas from liquid in buoyancy control tanks, and may result in some effervescence due to the heat dissipation into the liquid from the vehicle's radioisotope power supply, a potential noise source for sonar systems). The vehicle must also be delivered from the air, either by parachute extraction from or controlled ditching of a slender entry system, and must communicate its results back to Earth. Nominally the latter function is achieved with a large dorsal phased-array antenna, operated while surfaced, but solutions using an orbiting relay spacecraft and even communication while submerged, are being examined. While these aspects seem fantastical, in many respects the structural, propulsion and navigation/autonomy challenges of such a vehicle are little different from terrestrial autonomous underwater vehicles. We discuss the results of the study

  19. Evidence from acoustic imaging for submarine volcanic activity in 2012 off the west coast of El Hierro (Canary Islands, Spain)

    Science.gov (United States)

    Pérez, Nemesio M.; Somoza, Luis; Hernández, Pedro A.; de Vallejo, Luis González; León, Ricardo; Sagiya, Takeshi; Biain, Ander; González, Francisco J.; Medialdea, Teresa; Barrancos, José; Ibáñez, Jesús; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

    2014-12-01

    We report precursory geophysical, geodetic, and geochemical signatures of a new submarine volcanic activity observed off the western coast of El Hierro, Canary Islands. Submarine manifestation of this activity has been revealed through acoustic imaging of submarine plumes detected on the 20-kHz chirp parasound subbottom profiler (TOPAS PS18) mounted aboard the Spanish RV Hespérides on June 28, 2012. Five distinct "filament-shaped" acoustic plumes emanating from the flanks of mounds have been recognized at water depth between 64 and 88 m on a submarine platform located NW El Hierro. These plumes were well imaged on TOPAS profiles as "flares" of high acoustic contrast of impedance within the water column. Moreover, visible plumes composed of white rafts floating on the sea surface and sourcing from the location of the submarine plumes were reported by aerial photographs on July 3, 2012, 5 days after acoustic plumes were recorded. In addition, several geophysical and geochemical data support the fact that these submarine vents were preceded by several precursory signatures: (i) a sharp increase of the seismic energy release and the number of daily earthquakes of magnitude ≥2.5 on June 25, 2012, (ii) significant vertical and horizontal displacements observed at the Canary Islands GPS network (Nagoya University-ITER-GRAFCAN) with uplifts up to 3 cm from June 25 to 26, 2012, (iii) an anomalous increase of the soil gas radon activity, from the end of April until the beginning of June reaching peak values of 2.7 kBq/m3 on June 3, 2012, and (iv) observed positive peak in the air-corrected value of 3He/4He ratio monitored in ground waters (8.5 atmospheric 3He/4He ratio ( R A)) at the northwestern El Hierro on June 16, 2012. Combining these submarine and subaerial information, we suggest these plumes are the consequence of submarine vents exhaling volcanic gas mixed with fine ash as consequence of an event of rapid rise of volatile-rich magma beneath the NW submarine ridge

  20. Proton-induced noise in digicons

    Science.gov (United States)

    Smith, L. C.; Becher, J.; Fowler, W. B.; Flemming, K.

    1981-01-01

    The Space Telescope, which carries four Digicons, will pass several times per day through a low-altitude portion of the radiation belt called the South Atlantic Anomaly. This is expected to create interference in what is otherwise anticipated to be a noise-free device. Two essential components of the Digicon, the semiconductor diode array and the UV transmitting window, generate noise when subjected to medium-energy proton radiation, a primary component of the belt. These trapped protons, having energies ranging from 2 to 400 Mev and fluences at the Digicon up to 4,000 P+/sec-sq cm, pass through both the window and the diode array, depositing energy in each. In order to evaluate the effect of these protons, engineering test models of Digicon tubes to be flown on the High Resolution Spectrograph were irradiated with low-flux monoenergetic proton beams at the University of Maryland cyclotron. Electron-hole pairs produced by the protons passing through the diodes or the surrounding bulk caused a background count rate. This is the result of holes diffusing over a distance of many diode spacings, causing counts to be triggered simultaneously in the output circuits of several adjacent diodes. Pulse-height spectra of these proton-induced counts indicate that most of the bulk-related counts overlap the single photoelectron peak. A geometrical model will be presented of the charge collection characteristics of the diode array that accounts for most of the observed effects.