WorldWideScience

Sample records for survey surface velocities

  1. The derivation of an anisotropic velocity model from a combined surface and borehole seismic survey in crystalline environment at the COSC-1 borehole, central Sweden

    Science.gov (United States)

    Simon, H.; Buske, S.; Krauß, F.; Giese, R.; Hedin, P.; Juhlin, C.

    2017-09-01

    The Scandinavian Caledonides provide a well-preserved example of a Palaeozoic continent-continent collision, where surface geology in combination with geophysical data provides information about the geometry of parts of the Caledonian structure. The project COSC (Collisional Orogeny in the Scandinavian Caledonides) investigates the structure and physical conditions of the orogen units and the underlying basement with two approximately 2.5 km deep cored boreholes in western Jämtland, central Sweden. In 2014, the COSC-1 borehole was successfully drilled through a thick section of the Seve Nappe Complex. This tectonostratigraphic unit, mainly consisting of gneisses, belongs to the so-called Middle Allochthons and has been ductilely deformed and transported during the collisional orogeny. After the drilling, a major seismic survey was conducted in and around the COSC-1 borehole with the aim to recover findings on the structure around the borehole from core analysis and downhole logging. The survey comprised both seismic reflection and transmission experiments, and included zero-offset and multiazimuthal walkaway Vertical Seismic Profile (VSP) measurements, three long offset surface lines centred on the borehole, and a limited 3-D seismic survey. In this study, the data from the multiazimuthal walkaway VSP and the surface lines were used to derive detailed velocity models around the COSC-1 borehole by inverting the first-arrival traveltimes. The comparison of velocities from these tomography results with a velocity function calculated directly from the zero-offset VSP revealed clear differences in velocities for horizontally and vertically travelling waves. Therefore, an anisotropic VTI (transversely isotropic with vertical axis of symmetry) model was found that explains first-arrival traveltimes from both the surface and borehole seismic data. The model is described by a vertical P-wave velocity function derived from zero-offset VSP and the Thomsen parameters ε = 0

  2. Dispersion Energy Analysis of Rayleigh and Love Waves in the Presence of Low-Velocity Layers in Near-Surface Seismic Surveys

    Science.gov (United States)

    Mi, Binbin; Xia, Jianghai; Shen, Chao; Wang, Limin

    2017-10-01

    High-frequency surface-wave analysis methods have been effectively and widely used to determine near-surface shear (S) wave velocity. To image the dispersion energy and identify different dispersive modes of surface waves accurately is one of key steps of using surface-wave methods. We analyzed the dispersion energy characteristics of Rayleigh and Love waves in near-surface layered models based on numerical simulations. It has been found that if there is a low-velocity layer (LVL) in the half-space, the dispersion energy of Rayleigh or Love waves is discontinuous and ``jumping'' appears from the fundamental mode to higher modes on dispersive images. We introduce the guided waves generated in an LVL (LVL-guided waves, a trapped wave mode) to clarify the complexity of the dispersion energy. We confirm the LVL-guided waves by analyzing the snapshots of SH and P-SV wavefield and comparing the dispersive energy with theoretical values of phase velocities. Results demonstrate that LVL-guided waves possess energy on dispersive images, which can interfere with the normal dispersion energy of Rayleigh or Love waves. Each mode of LVL-guided waves having lack of energy at the free surface in some high frequency range causes the discontinuity of dispersive energy on dispersive images, which is because shorter wavelengths (generally with lower phase velocities and higher frequencies) of LVL-guided waves cannot penetrate to the free surface. If the S wave velocity of the LVL is higher than that of the surface layer, the energy of LVL-guided waves only contaminates higher mode energy of surface waves and there is no interlacement with the fundamental mode of surface waves, while if the S wave velocity of the LVL is lower than that of the surface layer, the energy of LVL-guided waves may interlace with the fundamental mode of surface waves. Both of the interlacements with the fundamental mode or higher mode energy may cause misidentification for the dispersion curves of surface

  3. Surface Velocities and Hydrology at Engabreen

    DEFF Research Database (Denmark)

    Messerli, Alexandra

    Recent studies have likened the seasonal observations of ice flow at the marginal regions of the Greenland Ice Sheet (GrIS) to those found on smaller alpine and valley counterparts. These similarities highlight the need for further small scale studies of seasonal evolution in the hydrological...... and dynamic structure of valley glaciers, to aid interpretation of observations from the margins of the GrIS. This thesis aims to collate a large suit of glacio-hydrological data from the outlet glacier Engabreen, Norway, in order to better understand the role the subglacial drainage configuration has...... on surface velocities recorded at the site. The Svartisen Subglacial Laboratory (SSL) under Engabreen, augmented by additional subglacial pressure and hydrological measurements, provides a invaluable observations for detailed process-oriented studies. However, the lack of complementary surface velocity data...

  4. Velocity Segregation and Systematic Biases In Velocity Dispersion Estimates with the SPT-GMOS Spectroscopic Survey

    Science.gov (United States)

    Bayliss, Matthew. B.; Zengo, Kyle; Ruel, Jonathan; Benson, Bradford A.; Bleem, Lindsey E.; Bocquet, Sebastian; Bulbul, Esra; Brodwin, Mark; Capasso, Raffaella; Chiu, I.-non; McDonald, Michael; Rapetti, David; Saro, Alex; Stalder, Brian; Stark, Antony A.; Strazzullo, Veronica; Stubbs, Christopher W.; Zenteno, Alfredo

    2017-03-01

    The velocity distribution of galaxies in clusters is not universal; rather, galaxies are segregated according to their spectral type and relative luminosity. We examine the velocity distributions of different populations of galaxies within 89 Sunyaev Zel’dovich (SZ) selected galaxy clusters spanning 0.28GMOS spectroscopic survey, supplemented by additional published spectroscopy, resulting in a final spectroscopic sample of 4148 galaxy spectra—2868 cluster members. The velocity dispersion of star-forming cluster galaxies is 17 ± 4% greater than that of passive cluster galaxies, and the velocity dispersion of bright (m< {m}* -0.5) cluster galaxies is 11 ± 4% lower than the velocity dispersion of our total member population. We find good agreement with simulations regarding the shape of the relationship between the measured velocity dispersion and the fraction of passive versus star-forming galaxies used to measure it, but we find a small offset between this relationship as measured in data and simulations, which suggests that our dispersions are systematically low by as much as 3% relative to simulations. We argue that this offset could be interpreted as a measurement of the effective velocity bias that describes the ratio of our observed velocity dispersions and the intrinsic velocity dispersion of dark matter particles in a published simulation result. Measuring velocity bias in this way suggests that large spectroscopic surveys can improve dispersion-based mass-observable scaling relations for cosmology even in the face of velocity biases, by quantifying and ultimately calibrating them out.

  5. UHF RiverSonde observations of water surface velocity at Threemile Slough, California

    Science.gov (United States)

    Teague, C.C.; Barrick, D.E.; Lilleboe, P.M.; Cheng, R.T.; Ruhl, C.A.

    2005-01-01

    A UHF RiverSonde system, operating near 350 MHz, has been in operation at Threemile Slough in central California, USA since September 2004. The water in the slough is dominated by tidal effects, with flow reversals four times a day and a peak velocity of about 0.8 m/s in each direction. Water level and water velocity are continually measured by the U. S. Geological Survey at the experiment site. The velocity is measured every 15 minutes by an ultrasonic velocity meter (UVM) which determines the water velocity from two-way acoustic propagation time-difference measurements made across the channel. The RiverSonde also measures surface velocity every 15 minutes using radar resonant backscatter techniques. Velocity and water level data are retrieved through a radio data link and a wideband internet connection. Over a period of several months, the radar-derived mean surface velocity has been very highly correlated with the UVM index velocity several meters below the surface, with a coefficient of determination R2 of 0.976 and an RMS difference of less than 10 cm/s. The wind has a small but measurable effect on the velocities measured by both instruments. In addition to the mean surface velocity across the channel, the RiverSonde system provides an estimate of the cross-channel variation of the surface velocity. ?? 2005 IEEE.

  6. Photon Doppler Velocimetry Measurements of Transverse Surface Velocities

    Science.gov (United States)

    Johnson, Christopher R.; Lajeunesse, Jeff; Sable, Peter; Hatzenbihler, Ashley; Borg, John P.

    2017-06-01

    Photon Doppler Velocimetry (PDV) is a prominent optical diagnostic used for measuring displacement or velocity in dynamic experiments. A table-top experiment consisting of a 31mm diameter metal wheel mounted in a hand tool was setup to make steady state transverse surface velocity measurements using PDV for a range of velocities and surface preparations. The experiment consisted of PDV collimators positioned with respect to either the side or bottom face of the wheel at various angles to resolve transverse velocity components. Different preparations for the surface of the wheel were explored such as polishing, laser etching, chemical etching, mechanical milling, and retroreflective microspheres. Light return and transverse surface velocity were recorded for each surface preparation as a function of angle. Polished aluminum allowed adequate light return for only one degree from the normal of the wheel, while the retroreflective microspheres exhibited usable light for upwards of 30 degrees. Velocity measurements were performed over a range of 0 to 45 degrees from the surface normal of the rotating wheel for each surface preparation. Velocity measurements from the PDV experiments show good accuracy with theoretical wheel velocities between 0 and 10 m/s.

  7. Surface Wave Velocity-Stress Relationship in Uniaxially Loaded Concrete

    DEFF Research Database (Denmark)

    Shokouhi, Parisa; Zoëga, Andreas; Wiggenhauser, Herbert

    2012-01-01

    loading cycles revealed that the velocities show a stress-memory effect in good agreement with the Kaiser effect. Comparing the velocities measured during loading and unloading, the effects of stress and damage on the measured velocities could be differentiated. Moreover, the stress dependency of surface......The sonic surface wave (or Rayleigh wave) velocity measured on prismatic concrete specimens under uniaxial compression was found to be highly stress-dependent. At low stress levels, the acoustoelastic effect and the closure of existing microcracks results in a gradual increase in surface wave...... velocities. At higher stress levels, concrete suffers irrecoverable damage: the existing microcracks widen and coalesce and new microcracks form. This progressive damage process leads first to the flattening and eventually the drop in the velocity-stress curves. Measurements on specimens undergoing several...

  8. Surface recombination velocity of silicon wafers by photoluminescence

    Science.gov (United States)

    Baek, D.; Rouvimov, S.; Kim, B.; Jo, T.-C.; Schroder, D. K.

    2005-03-01

    Photoluminescence (PL) and optical reflection measurements, obtained in the two-wavelength SiPHER PL instrument, are used to determine the surface recombination velocity of silicon wafers. Local measurements and contour maps are possible allowing surface recombination maps to be displayed. This instrument also allows doping and trap density measurements. Surface recombination velocities from 10 to 106cm/s can be measured on low or high resistivity polished and epitaxial wafers.

  9. Influence of the surface finishing on ultrasound velocity in wood

    Directory of Open Access Journals (Sweden)

    Tomáš Špaček

    2008-01-01

    Full Text Available Non-destructive diagnostic methods are very useful for monumental buildings. This paper deals with one of these technique, namely with ultrasound testing and influence of surface finishing on ultrasound velocity measured by means of device the Arborsonic Decay Detector. Surface finishing (Primalex – thick synthetic film of the surface finishing, Luxol – Extra – thin synthetic film of the surface finishing and Impranal Profi SL – thick acryl film the surface finishing were selected and tested in this research. The transmittion time was measured and velocity was converted from it. This was compared before and after application of surface finishing.

  10. Simulating Precursor Radial Velocity Surveys for Future Exoplanet Direct Imaging Missions

    Science.gov (United States)

    Newman, Patrick; Plavchan, Peter; Crepp, Justin; Dulz, Shannon; Stark, Chris; Kane, Steven

    2018-01-01

    Future direct imaging missions such as WFIRST, HabEx, and LUVOIR aim to catalog and characterize Earth-analogs around nearby stars. The observing strategy and science yield and are strongly dependent on the frequency of Earth-like planets, and precursor knowledge of which stars specifically host suitable planetary systems. Ground-based radial velocity surveys can potentially identify targets and optimal observations times at a fraction of the cost of blind direct imaging surveys. We present the first phases of simulations of such a survey. We consider multiple telescopes, including their locations, weather conditions, observation time limitations, and instrument sensitivities. Multiple target selection optimization algorithms are considered. We calculate realistic radial velocity uncertainties based upon the known stellar properties of nearby direct imaging targets including effective temperature, metallicity, and surface gravity. We next inject and recover the masses and orbital parameters of real and simulated planets, estimating the effectiveness of a precursor radial velocity survey for direct imaging yield optimization.

  11. The stress-induced surface wave velocity variations in concrete

    Science.gov (United States)

    Spalvier, Agustin; Bittner, James; Evani, Sai Kalyan; Popovics, John S.

    2017-02-01

    This investigation studies the behavior of surface wave velocity in concrete specimens subjected to low levels of compressive and tensile stress in beams from applied flexural loads. Beam specimen is loaded in a 4-point-load bending configuration, generating uniaxial compression and tension stress fields at the top and bottom surfaces of the beam, respectively. Surface waves are generated through contactless air-coupled transducers and received through contact accelerometers. Results show a clear distinction in responses from compression and tension zones, where velocity increases in the former and decreases in the latter, with increasing load levels. These trends agree with existing acoustoelastic literature. Surface wave velocity tends to decrease more under tension than it tends to increase under compression, for equal load levels. It is observed that even at low stress levels, surface wave velocity is affected by acoustoelastic effects, coupled with plastic effects (stress-induced damage). The acoustoelastic effect is isolated by means of considering the Kaiser effect and by experimentally mitigating the viscoelastic effects of concrete. Results of this ongoing investigation contribute to the overall knowledge of the acoustoelastic behavior of concrete. Applications of this knowledge may include structural health monitoring of members under flexural loads, improved high order modelling of materials, and validation of results seen in dynamic acoustoelasticity testing.

  12. Bok Prize Lecture (shared) The Brown Dwarf Radial Velocity Survey

    Science.gov (United States)

    Charbonneau, Dave

    2004-03-01

    The swarm of nearby brown dwarfs and very low mass stars is an attractive sample for radial velocity monitoring. Such work is best conducted with an echelle spectrograph operating at infrared wavelengths where these objects(i) are most luminous, (ii) have a forest of molecular features, providing an excellent velocity metric, and {iii) are superimposed on the telluric spectrum, which yields the requisite wavelength calibration. I will present first results from such a survey, with a precision sufficient to detect Jupiter-mass planets with orbital periods of less than a year. Should such systems be uncovered, the planets would be amenable to direct study, due to system proximity, and the favorable contrast ratio between the planet and parent object.

  13. Peculiar velocity decomposition, redshift space distortion, and velocity reconstruction in redshift surveys: The methodology

    Science.gov (United States)

    Zhang, Pengjie; Pan, Jun; Zheng, Yi

    2013-03-01

    Massive spectroscopic surveys will measure the redshift space distortion (RSD) induced by galaxy peculiar velocity to unprecedented accuracy and open a new era of precision RSD cosmology. We develop a new method to improve the RSD modeling and to carry out robust reconstruction of the 3D large scale peculiar velocity through galaxy redshift surveys, in light of RSD. (1) We propose a mathematically unique and physically motivated decomposition of peculiar velocity into three eigencomponents: an irrotational component completely correlated with the underlying density field (vδ), an irrotational component uncorrelated with the density field (vS), and a rotational (curl) component (vB). The three components have different origins, different scale dependences, and different impacts on RSD. (2) This decomposition has the potential to simplify and improve the RSD modeling. (i) vB damps the redshift space clustering. (ii) vS causes both damping and enhancement to the redshift space power spectrum Ps(k,u). Nevertheless, the leading order contribution to the enhancement has a u4 directional dependence, distinctively different from the Kaiser formula. Here, u≡kz/k, k is the amplitude of the wave vector, and kz is the component along the line of sight. (iii) vδ is of the greatest importance for the RSD cosmology. We find that the induced redshift clustering shows a number of important deviations from the usual Kaiser formula. Even in the limit of vS→0 and vB→0, the leading order contribution ∝(1+fW˜(k)u2)2. It differs from the Kaiser formula by a window function W˜(k). Nonlinear evolution generically drives W˜(k)≤1. We hence identify a significant systematical error causing underestimation of the structure growth parameter f by as much as O(10%) even at a relatively large scale k=0.1h/Mpc. (iv) The velocity decomposition reveals the three origins of the “finger-of-God” (FOG) effect and suggests how to simplify and improve the modeling of FOG by treating the

  14. Retrieval of sea surface velocities using sequential Ocean Colour ...

    Indian Academy of Sciences (India)

    Sequential data of IRS-P4 OCM has been analysed over parts of both east and west coast of India and a methodology to retrieve sea surface current velocities has ... Presently at Applied Geophysical Laboratories, Department of Geophysics, University of Houston, Texas 77204, USA; Marine and Water Resources Group, ...

  15. Near-Surface Seismic Velocity Data: A Computer Program For ...

    African Journals Online (AJOL)

    A computer program (NESURVELANA) has been developed in Visual Basic Computer programming language to carry out a near surface velocity analysis. The method of analysis used includes: Algorithms design and Visual Basic codes generation for plotting arrival time (ms) against geophone depth (m) employing the ...

  16. Optimal strategies of radial velocity observations in planet search surveys

    Science.gov (United States)

    Baluev, Roman V.

    2008-09-01

    Applications of the theory of optimal design of experiments to radial velocity (RV) planet search surveys are considered. Different optimality criteria are discussed, basing on the Fisher, Shannon and Kullback-Leibler informations. Algorithms of optimal scheduling of RV observations for two important practical problems are considered. The first problem is finding the time for future observations to yield the maximum improvement of the precision of exoplanetary orbital parameters and masses. The second problem is finding the most favourable time for distinguishing alternative orbital fits (the scheduling of discriminating observations). These methods of optimal planning are demonstrated to be potentially efficient for multiplanet extrasolar systems, in particular for resonant ones. In these cases, the optimal dates of observations are often concentrated in quite narrow time segments.

  17. Prediction of fluid velocity slip at solid surfaces

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Todd, Billy; Daivis, Peter

    2011-01-01

    The observed flow enhancement in highly confining geometries is believed to be caused by fluid velocity slip at the solid wall surface. Here we present a simple and highly accurate method to predict this slip using equilibrium molecular dynamics. Unlike previous equilibrium molecular dynamics...... methods, it allows us to directly compute the intrinsic wall-fluid friction coefficient rather than an empirical friction coefficient that includes all sources of friction for planar shear flow. The slip length predicted by our method is in excellent agreement with the slip length obtained from direct...

  18. Estimation of near-surface shear-wave velocities and quality factors using multichannel analysis of surface-wave methods

    Science.gov (United States)

    Xia, Jianghai

    2014-04-01

    This overview article gives a picture of multichannel analysis of high-frequency surface (Rayleigh and Love) waves developed mainly by research scientists at the Kansas Geological Survey, the University of Kansas and China University of Geosciences (Wuhan) during the last eighteen years by discussing dispersion imaging techniques, inversion systems, and real-world examples. Shear (S)-wave velocities of near-surface materials can be derived from inverting the dispersive phase velocities of high-frequency surface waves. Multichannel analysis of surface waves—MASW used phase information of high-frequency Rayleigh waves recorded on vertical component geophones to determine near-surface S-wave velocities. The differences between MASW results and direct borehole measurements are approximately 15% or less and random. Studies show that inversion with higher modes and the fundamental mode simultaneously can increase model resolution and an investigation depth. Multichannel analysis of Love waves—MALW used phase information of high-frequency Love waves recorded on horizontal (perpendicular to the direction of wave propagation) component geophones to determine S-wave velocities of shallow materials. Because of independence of compressional (P)-wave velocity, the MALW method has some attractive advantages, such as 1) Love-wave dispersion curves are simpler than Rayleigh wave's; 2) dispersion images of Love-wave energy have a higher signal to noise ratio and more focused than those generated from Rayleigh waves; and 3) inversion of Love-wave dispersion curves is less dependent on initial models and more stable than Rayleigh waves.

  19. Imaging of surface wave phase velocities from array phase observations

    Science.gov (United States)

    Weidle, Christian; Maupin, Valerie

    2010-05-01

    While temporary deployments some 10 years ago were largely based on short-period seismometers, the availability of broadband instruments in instrument pools increased strongly in recent years and as such modern temporary deployments for passive seismological recordings often consist to a large extent, if not exclusively, of broadband instruments. This opens for new analysis approaches as the broadband seismic wavefield is obtained at a relatively high spatial sampling relative to the wavelength. In an attempt to infer surface wave phase velocity anomalies beneath Southern Norway based on data from a temporary network of 41 broadband instruments, we present a new approach to overcome the limitations of two-station phase measurements (on the great circle with the source) and instead exploit the two-dimensional nature of the wavefield by taking into account phase measurements at all stations of the array from a single event. This is based on the assumption that the wavefield is at least piecewise linear within the study region. By triangulation of the network region and linear estimation of the phase gradient in each triangle we get without further a priori assumptions a coarse image of the phase velocity variations within our network. The image can be significantly refined for a single event recording by stacking multiple images based on arbitrary subsets of the available data. Phase velocity anomalies measured from single event recordings can be biased and blurred by non-plane arriving wavefield, reflections and diffractions of heterogeneities. Therefore, by averaging over velocity fields from different events with varying backazimuths, artefacts are reduced and the recovered image significantly improved. Another way to improve the recovered structures is to take into account the spatial variation of the amplitude field. However, while the phase between two neighboring stations may be (at least close to) linear, the amplitude may not, hence estimation of the second

  20. Impact of Assimilating Surface Velocity Observations on the Model Sea Surface Height Using the NCOM-4DVAR

    Science.gov (United States)

    2016-09-26

    the surface velocity observations, the pro- cessed GLAD velocities are available in 15- min in- tervals; however, these data are only assimilated... data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this...variational data assimilation (4DVAR) analysis component. In this work, drifter-derived surface velocity observations are assimilated into the

  1. Conventional Point-Velocity Records and Surface Velocity Observations for Estimating High Flow Discharge

    Directory of Open Access Journals (Sweden)

    Giovanni Corato

    2014-10-01

    Full Text Available Flow velocity measurements using point-velocity meters are normally obtained by sampling one, two or three velocity points per vertical profile. During high floods their use is inhibited due to the difficulty of sampling in lower portions of the flow area. Nevertheless, the application of standard methods allows estimation of a parameter, α, which depends on the energy slope and the Manning roughness coefficient. During high floods, monitoring of velocity can be accomplished by sampling the maximum velocity, umax, only, which can be used to estimate the mean flow velocity, um, by applying the linear entropy relationship depending on the parameter, M, estimated on the basis of historical observed pairs (um, umax. In this context, this work attempts to analyze if a correlation between α and M holds, so that the monitoring for high flows can be addressed by exploiting information from standard methods. A methodology is proposed to estimate M from α, by coupling the “historical” information derived by standard methods, and “new” information from the measurement of umax surmised at later times. Results from four gauged river sites of different hydraulic and geometric characteristics have shown the robust estimation of M based on α.

  2. Near‐surface void detection using a seismic landstreamer and horizontal velocity and attenuation tomography

    Science.gov (United States)

    Buckley, Sean F.; Lane, John W.

    2012-01-01

    The detection and characterization of subsurface voids plays an important role in the study of karst formations and clandestine tunnels. Horizontal velocity and attenuation tomography (HVAT) using offset‐fan shooting and a towed seismic land streamer is a simple, rapid, minimally invasive method that shows promise for detecting near‐surface voids and providing information on the orientation of linear voids. HVAT surveys were conducted over a known subsurface steam tunnel on the University of Connecticut Depot Campus, Storrs, Connecticut. First‐arrival travel‐time and amplitude data were used to produce two‐dimensional (2D) horizontal (map view) velocity and attenuation tomograms. In addition, attenuation tomograms were produced based on normalized total trace energy (TTE). Both the velocity and TTE attenuation tomograms depict an anomaly consistent with the location and orientation of the known tunnel; the TTE method, however, requires significantly less processing time, and therefore may provide a path forward to semi‐automated, near real‐time detection of near‐surface voids. Further study is needed to assess the utility of the HVAT method to detect deeper voids and the effects of a more complex geology on HVAT results.

  3. Estimation of unsteady lift on a pitching airfoil from wake velocity surveys

    Science.gov (United States)

    Zaman, K. B. M. Q.; Panda, J.; Rumsey, C. L.

    1993-01-01

    The results of a joint experimental and computational study on the flowfield over a periodically pitched NACA0012 airfoil, and the resultant lift variation, are reported in this paper. The lift variation over a cycle of oscillation, and hence the lift hysteresis loop, is estimated from the velocity distribution in the wake measured or computed for successive phases of the cycle. Experimentally, the estimated lift hysteresis loops are compared with available data from the literature as well as with limited force balance measurements. Computationally, the estimated lift variations are compared with the corresponding variation obtained from the surface pressure distribution. Four analytical formulations for the lift estimation from wake surveys are considered and relative successes of the four are discussed.

  4. Ascent Velocity of Plasmoids Generated by Surface Discharges

    Science.gov (United States)

    Wenzel, Uwe

    The ascent velocity of long-lived plasmoids generated under atmospheric conditions to simulate ball lightning was estimated in [Fussmann et al., Phys. Unserer Zeit 39, 246 (2008) and Jegorov et al., Tech. Phys. 53, 688 (2008): Refs. 1 and 2 in the text, respectively], using a rigid sphere model with poor agreement with the experiment. The plasmoids were, however, deformed. Much better agreement is obtained using the Davies and Taylor formula, which describes the ascent velocity of large spherical-cap bubbles.

  5. Influence of shear velocity on frictional characteristics of rock surface

    Indian Academy of Sciences (India)

    The phenomenon of stick-slip of granite and shaly sandstone with a tribometer at constant rate of strain under normal loads was observed. Friction at the interface of the rock samples was developed by increasing shear strain at a constant rate by applying constant velocity using the tribometer. For shaly sandstone, state ...

  6. Measuring surface current velocities in the Agulhas region with ASAR

    CSIR Research Space (South Africa)

    Rouault, MJ

    2010-01-01

    Full Text Available Surface current information collected over the Agulhas Current region and derived from the Doppler centroid anomalies of the Advanced Synthetic Aperture Radar (ASAR) are examined. The sources of errors and potential use of the radar surface...

  7. Velocity dependence of sliding friction on a crystalline surface

    Directory of Open Access Journals (Sweden)

    Christian Apostoli

    2017-10-01

    Full Text Available We introduce and study a minimal 1D model for the simulation of dynamic friction and dissipation at the atomic scale. This model consists of a point mass (slider that moves over and interacts weakly with a linear chain of particles interconnected by springs, representing a crystalline substrate. This interaction converts a part of the kinetic energy of the slider into phonon waves in the substrate. As a result, the slider experiences a friction force. As a function of the slider speed, we observe dissipation peaks at specific values of the slider speed, whose nature we understand by means of a Fourier analysis of the excited phonon modes. By relating the phonon phase velocities with the slider velocity, we obtain an equation whose solutions predict which phonons are being excited by the slider moving at a given speed.

  8. Near-surface fault detection by migrating back-scattered surface waves with and without velocity profiles

    KAUST Repository

    Yu, Han

    2016-04-26

    We demonstrate that diffraction stack migration can be used to discover the distribution of near-surface faults. The methodology is based on the assumption that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. We first isolate the back-scattered surface waves by muting or FK filtering, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. We have also proposed a natural migration method that utilizes the intrinsic traveltime property of the direct and the back-scattered waves at faults. For the synthetic data sets and the land data collected in Aqaba, where surface wave velocity has unexpected perturbations, we migrate the back-scattered surface waves with both predicted velocity profiles and natural Green\\'s function without velocity information. Because the latter approach avoids the need for an accurate velocity model in event summation, both the prestack and stacked migration images show competitive quality. Results with both synthetic data and field records validate the feasibility of this method. We believe applying this method to global or passive seismic data can open new opportunities in unveiling tectonic features.

  9. Calculating wave-generated bottom orbital velocities from surface-wave parameters

    Science.gov (United States)

    Wiberg, P.L.; Sherwood, C.R.

    2008-01-01

    Near-bed wave orbital velocities and shear stresses are important parameters in many sediment-transport and hydrodynamic models of the coastal ocean, estuaries, and lakes. Simple methods for estimating bottom orbital velocities from surface-wave statistics such as significant wave height and peak period often are inaccurate except in very shallow water. This paper briefly reviews approaches for estimating wave-generated bottom orbital velocities from near-bed velocity data, surface-wave spectra, and surface-wave parameters; MATLAB code for each approach is provided. Aspects of this problem have been discussed elsewhere. We add to this work by providing a method for using a general form of the parametric surface-wave spectrum to estimate bottom orbital velocity from significant wave height and peak period, investigating effects of spectral shape on bottom orbital velocity, comparing methods for calculating bottom orbital velocity against values determined from near-bed velocity measurements at two sites on the US east and west coasts, and considering the optimal representation of bottom orbital velocity for calculations of near-bed processes. Bottom orbital velocities calculated using near-bed velocity data, measured wave spectra, and parametric spectra for a site on the northern California shelf and one in the mid-Atlantic Bight compare quite well and are relatively insensitive to spectral shape except when bimodal waves are present with maximum energy at the higher-frequency peak. These conditions, which are most likely to occur at times when bottom orbital velocities are small, can be identified with our method as cases where the measured wave statistics are inconsistent with Donelan's modified form of the Joint North Sea Wave Project (JONSWAP) spectrum. We define the 'effective' forcing for wave-driven, near-bed processes as the product of the magnitude of forcing times its probability of occurrence, and conclude that different bottom orbital velocity statistics

  10. Using remotely sensed data to estimate river characteristics including water-surface velocity and discharge

    Science.gov (United States)

    Nelson, Jonathan M.; Kinzel, Paul J.; Legleiter, Carl; McDonald, Richard R.; Overstreet, Brandon; Conaway, Jeff

    2017-01-01

    This paper describes a project combining field studies and analyses directed at providing an assessment of the accuracy of remotely sensed methods for determining river characteristics such as velocity and discharge. In particular, we describe a remote sensing method for surface velocities using mid-wave thermal camera videography combined with image analysis. One of the critical problems in this work is determining a method for relating remotely measured water-surface velocities to vertically averaged velocities through a velocity index. We explore three similarity profiles that allow a relationship between surface and vertically averaged velocity to be found either using empirical results or simple roughness-to-depth ratios. To test the approaches we compare them in a situation where vertical structure is known over most of the flow depth through ADCP measurements. By determining best-fit profiles through the ADCP profiles, average values of the velocity index are found for the cross-sections where measurement were made. By comparing these to the predicted velocity indices from the three similarity profiles, we find that, although the differences between the various similarity profiles are substantial, they are smaller than differences associated with local nonuniformity and nonhydrostatic flow. Nevertheless, the velocity indices are accurate to about +/-5%, meaning that remotely sensed vertically averaged velocities can be computed to well within the current accuracy standard for such values when used for river gaging.

  11. The SDSS-III APOGEE radial velocity survey of M dwarfs. I. Description of the survey and science goals

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, R.; Bender, C. F.; Mahadevan, S.; Terrien, R. C.; Schneider, D. P.; Fleming, S. W. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, PA 16802 (United States); Blake, C. H. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Carlberg, J. K. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Zasowski, G.; Hearty, F. [University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Crepp, J. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Rajpurohit, A. S.; Reylé, C. [Institut UTINAM, CNRS UMR 6213, Observatoire des Sciences de l' Univers THETA Franche-Comt é-Bourgogne, Université de Franche Comté, Observatoire de Besançon, BP 1615, F-25010 Besançon Cedex (France); Nidever, D. L. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Prieto, C. Allende; Hernández, J. [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Bizyaev, D. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Ebelke, G. [Department of Physics and Astronomy, Texas Christian University, TCU Box 298840, Fort Worth, TX 76129 (United States); Frinchaboy, P. M. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States); Ge, J. [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States); and others

    2013-12-01

    We are carrying out a large ancillary program with the Sloan Digital Sky Survey, SDSS-III, using the fiber-fed multi-object near-infrared APOGEE spectrograph, to obtain high-resolution H-band spectra of more than 1200 M dwarfs. These observations will be used to measure spectroscopic rotational velocities, radial velocities, physical stellar parameters, and variability of the target stars. Here, we describe the target selection for this survey, as well as results from the first year of scientific observations based on spectra that will be publicly available in the SDSS-III DR10 data release. As part of this paper we present radial velocities and rotational velocities of over 200 M dwarfs, with a vsin i precision of ∼2 km s{sup –1} and a measurement floor at vsin i = 4 km s{sup –1}. This survey significantly increases the number of M dwarfs studied for rotational velocities and radial velocity variability (at ∼100-200 m s{sup –1}), and will inform and advance the target selection for planned radial velocity and photometric searches for low-mass exoplanets around M dwarfs, such as the Habitable Zone Planet Finder, CARMENES, and TESS. Multiple epochs of radial velocity observations enable us to identify short period binaries, and adaptive optics imaging of a subset of stars enables the detection of possible stellar companions at larger separations. The high-resolution APOGEE spectra, covering the entire H band, provide the opportunity to measure physical stellar parameters such as effective temperatures and metallicities for many of these stars. At the culmination of this survey, we will have obtained multi-epoch spectra and radial velocities for over 1400 stars spanning the spectral range M0-L0, providing the largest set of near-infrared M dwarf spectra at high resolution, and more than doubling the number of known spectroscopic vsin i values for M dwarfs. Furthermore, by modeling telluric lines to correct for small instrumental radial velocity shifts, we

  12. A numerical method for predicting Rayleigh surface wave velocity in anisotropic crystals

    Science.gov (United States)

    Cherry, Matthew R.; Sathish, Shamachary; Grandhi, Ramana

    2017-12-01

    A numerical method was developed for calculating the Rayleigh Surface Wave (RSW) velocity in arbitrarily oriented single crystals in 360 degrees of propagation. This method relies on the results from modern analysis of RSW behavior with the Stroh formalism to restrict the domain in which to search for velocities by first calculating the limiting velocity. This extension of existing numerical methods also leads to a natural way of determining both the existence of the RSW as well as the possibility of encountering a pseudo-surface wave. Furthermore, the algorithm is applied to the calculation of elastic properties from measurement of the surface wave velocity in multiple different directions on a single crystal sample. The algorithm was tested with crystal symmetries and single crystal elastic moduli from literature. It was found to be very robust and efficient in calculating RSW velocity curves in all cases.

  13. Measurement of lithium target surface velocity in the IFMIF/EVEDA lithium test loop

    Energy Technology Data Exchange (ETDEWEB)

    Kanemura, Takuji, E-mail: kanemura.takuji@jaea.go.jp [Japan Atomic Energy Agency, 4002 Narita, O-arai, Higashi-Ibaraki-gun, Ibaraki 311-1393 (Japan); Kondo, Hiroo; Furukawa, Tomohiro; Hirakawa, Yasushi [Japan Atomic Energy Agency, 4002 Narita, O-arai, Higashi-Ibaraki-gun, Ibaraki 311-1393 (Japan); Hoashi, Eiji [Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Yoshihashi, Sachiko; Horiike, Hiroshi [Fukui University of Technology, Gakuen 3-6-1, Fukui-shi, Fukui 910-8505 (Japan); Wakai, Eiichi [Japan Atomic Energy Agency, 4002 Narita, O-arai, Higashi-Ibaraki-gun, Ibaraki 311-1393 (Japan)

    2016-11-01

    Highlights: • The objective is to measure the free-surface velocity field of the IFMIF Li target. • The Li target has an important role to remove 10 MW heat input from a deuteron beam. • The free-surface of the Li target is under the most severe heat load condition. • Measured surface velocities are almost equal to cross-sectional average velocities. • It was confirmed that the IFMIF Li target has adequate heat removal performance. - Abstract: In the framework of the Engineering Validation and Engineering Design Activities (EVEDA) project of the International Fusion Materials Irradiation Facility (IFMIF), we measured surface velocity fields of a lithium (Li) target at the EVEDA Li test loop under specifically-designated IFMIF conditions (target speeds of 10, 15, and 20 m/s, vacuum pressure of 10{sup −3} Pa, and Li temperature of 250 °C). In the current design of the IFMIF, the free surface of the Li target is under a most severe heat load condition with respect to Li boiling. The objective of this study is to measure the actual free-surface velocity under these IFMIF conditions to evaluate the heat removal performance of the Li target. The measured results (using the surface-wave tracking method that our team developed) showed two-dimensional time-averaged velocity distributions around the IFMIF beam footprint being virtually uniform, and close to the cross-sectional average velocity. The uniformity of the velocity distributions was less than 1 m/s. The comparison between the measured and analyzed surface velocity at the beam center showed that the analysis accurately predicts the measurement results within a margin of 3%. Finally, it was confirmed that the Li target delivers adequate heat removal performance in the IFMIF as designed.

  14. From Surface Flow Velocity Measurements to Discharge Assessment by the Entropy Theory

    Directory of Open Access Journals (Sweden)

    Tommaso Moramarco

    2017-02-01

    Full Text Available A new methodology for estimating the discharge starting from the monitoring of surface flow velocity, usurf, is proposed. The approach, based on the entropy theory, involves the actual location of maximum flow velocity, umax, which may occur below the water surface (dip phenomena, affecting the shape of velocity profile. The method identifies the two-dimensional velocity distribution in the cross-sectional flow area, just sampling usurf and applying an iterative procedure to estimate both the dip and umax. Five gage sites, for which a large velocity dataset is available, are used as a case study. Results show that the method is accurate in simulating the depth-averaged velocities along the verticals and the mean flow velocity with an error, on average, lower than 12% and 6%, respectively. The comparison with the velocity index method for the estimation of the mean flow velocity using the measured usurf, demonstrates that the method proposed here is more accurate mainly for rivers with a lower aspect ratio where secondary currents are expected. Moreover, the dip assessment is found more representative of the actual location of maximum flow velocity with respect to the one estimated by a different entropy approach. In terms of discharge, the errors do not exceed 3% for high floods, showing the good potentiality of the method to be used for the monitoring of these events.

  15. Glacier Surface Velocity Measurements from Radar Interferometry and the Principle of Mass Conservation

    DEFF Research Database (Denmark)

    Mohr, Johan Jacob; Reeh, Niels

    2002-01-01

    Presents a relation between the three glacier surface velocity components, the surface flux-divergence, glacier thickness and bottom melt and displacement. The relation can be used as an extension to the surface parallel flow assumption often used with interferometric synthetic aperture measureme...

  16. Influence of shear velocity on frictional characteristics of rock surface

    Indian Academy of Sciences (India)

    133 024702, doi: 10.1063/1.3460530. Martins J A C, Guimaraes J and Faria L O 1995 Dynamic surface solutions in linear elasticity and viscoelasticity with frictional boundary conditions; J. Vibration Acoust. Trans. ASME 117 445–451. Matsukawa H and Saito T 2007 Friction, stick-slip and earthquake; Lecture Notes Phys.

  17. Double-lined Spectroscopic Binary Stars in the Radial Velocity Experiment Survey

    NARCIS (Netherlands)

    Matijevič, G.; Zwitter, T.; Munari, U.; Bienaymé, O.; Binney, J.; Bland-Hawthorn, J.; Boeche, C.; Campbell, R.; Freeman, K. C.; Gibson, B.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Navarro, J. F.; Parker, Q. A.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Steinmetz, M.; Watson, F. G.; Williams, M.; Wyse, R. F. G.

    We devise a new method for the detection of double-lined binary stars in a sample of the Radial Velocity Experiment (RAVE) survey spectra. The method is both tested against extensive simulations based on synthetic spectra and compared to direct visual inspection of all RAVE spectra. It is based on

  18. Surface velocity divergence model of air/water interfacial gas transfer in open-channel flows

    Science.gov (United States)

    Sanjou, M.; Nezu, I.; Okamoto, T.

    2017-04-01

    Air/water interfacial gas transfer through a free surface plays a significant role in preserving and restoring water quality in creeks and rivers. However, direct measurements of the gas transfer velocity and reaeration coefficient are still difficult, and therefore a reliable prediction model needs to be developed. Varying systematically the bulk-mean velocity and water depth, laboratory flume experiments were conducted and we measured surface velocities and dissolved oxygen (DO) concentrations in open-channel flows to reveal the relationship between DO transfer velocity and surface divergence (SD). Horizontal particle image velocimetry measurements provide the time-variations of surface velocity divergence. Positive and negative regions of surface velocity divergence are transferred downstream in time, as occurs in boil phenomenon on natural river free-surfaces. The result implies that interfacial gas transfer is related to bottom-situated turbulence motion and vertical mass transfer. The original SD model focuses mainly on small-scale viscous motion, and this model strongly depends on the water depth. Therefore, we modify the SD model theoretically to accommodate the effects of the water depth on gas transfer, introducing a non-dimensional parameter that includes contributions of depth-scale large-vortex motion, such as secondary currents, to surface renewal events related to DO transport. The modified SD model proved effective and reasonable without any dependence on the bulk mean velocity and water depth, and has a larger coefficient of determination than the original SD model. Furthermore, modeling of friction velocity with the Reynolds number improves the practicality of a new formula that is expected to be used in studies of natural rivers.

  19. Reconstruction of Sub-Surface Velocities from Satellite Observations Using Iterative Self-Organizing Maps

    CERN Document Server

    Chapman, Christopher

    2016-01-01

    In this letter a new method based on modified self-organizing maps is presented for the reconstruction of deep ocean current velocities from surface information provided by satellites. This method takes advantage of local correlations in the data-space to improve the accuracy of the reconstructed deep velocities. Unlike previous attempts to reconstruct deep velocities from surface data, our method makes no assumptions regarding the structure of the water column, nor the underlying dynamics of the flow field. Using satellite observations of surface velocity, sea-surface height and sea-surface temperature, as well as observations of the deep current velocity from autonomous Argo floats to train the map, we are able to reconstruct realistic high--resolution velocity fields at a depth of 1000m. Validation reveals extremely promising results, with a speed root mean squared error of ~2.8cm/s, a factor more than a factor of two smaller than competing methods, and direction errors consistently smaller than 30 degrees...

  20. A new all-sky map of Galactic high-velocity clouds from the 21-cm HI4PI survey

    Science.gov (United States)

    Westmeier, Tobias

    2018-02-01

    High-velocity clouds (HVCs) are neutral or ionized gas clouds in the vicinity of the Milky Way that are characterized by high radial velocities inconsistent with participation in the regular rotation of the Galactic disc. Previous attempts to create a homogeneous all-sky H I map of HVCs have been hampered by a combination of poor angular resolution, limited surface brightness sensitivity and suboptimal sampling. Here, a new and improved H I map of Galactic HVCs based on the all-sky HI4PI survey is presented. The new map is fully sampled and provides significantly better angular resolution (16.2 versus 36 arcmin) and column density sensitivity (2.3 versus 3.7 × 1018 cm-2 at the native resolution) than the previously available LAB survey. The new HVC map resolves many of the major HVC complexes in the sky into an intricate network of narrow H I filaments and clumps that were not previously resolved by the LAB survey. The resulting sky coverage fraction of high-velocity H I emission above a column density level of 2 × 1018 cm-2 is approximately 15 per cent, which reduces to about 13 per cent when the Magellanic Clouds and other non-HVC emission are removed. The differential sky coverage fraction as a function of column density obeys a truncated power law with an exponent of -0.93 and a turnover point at about 5 × 1019 cm-2. H I column density and velocity maps of the HVC sky are made publicly available as FITS images for scientific use by the community.

  1. THE RINGS SURVEY. I. Hα AND H i VELOCITY MAPS OF GALAXY NGC 2280

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Carl J.; Williams, T. B.; Sellwood, J. A. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Spekkens, Kristine; Lee-Waddell, K. [Department of Physics, Royal Military College of Canada, P.O. Box 17000, Station Forces, Kingston, ON, K7K 7B4, XNS (Canada); Naray, Rachel Kuzio de, E-mail: cmitchell@physics.rutgers.edu, E-mail: williams@saao.ac.za, E-mail: kristine.spekkens@rmc.ca, E-mail: karen.lee-waddell@rmc.ca, E-mail: kuzio@astro.gsu.edu, E-mail: sellwood@physics.rutgers.edu [Department of Physics and Astronomy, Georgia State University, 25 Park Place, Atlanta, GA 30303 (United States)

    2015-03-15

    Precise measurements of gas kinematics in the disk of a spiral galaxy can be used to estimate its mass distribution. The Southern African Large Telescope has a large collecting area and field of view, and is equipped with a Fabry–Pérot (FP) interferometer that can measure gas kinematics in a galaxy from the Hα line. To take advantage of this capability, we have constructed a sample of 19 nearby spiral galaxies, the RSS Imaging and Spectroscopy Nearby Galaxy Survey, as targets for detailed study of their mass distributions and have collected much of the needed data. In this paper, we present velocity maps produced from Hα FP interferometry and H i aperture synthesis for one of these galaxies, NGC 2280, and show that the two velocity measurements are generally in excellent agreement. Minor differences can mostly be attributed to the different spatial distributions of the excited and neutral gas in this galaxy, but we do detect some anomalous velocities in our Hα velocity map of the kind that have previously been detected in other galaxies. Models produced from our two velocity maps agree well with each other and our estimates of the systemic velocity and projection angles confirm previous measurements of these quantities for NGC 2280.

  2. A simple measuring technique of surface flow velocity to analyze the behavior of velocity fields in hydraulic engineering applications.

    Science.gov (United States)

    Tellez, Jackson; Gomez, Manuel; Russo, Beniamino; Redondo, Jose M.

    2015-04-01

    An important achievement in hydraulic engineering is the proposal and development of new techniques for the measurement of field velocities in hydraulic problems. The technological advances in digital cameras with high resolution and high speed found in the market, and the advances in digital image processing techniques now provides a tremendous potential to measure and study the behavior of the water surface flows. This technique was applied at the Laboratory of Hydraulics at the Technical University of Catalonia - Barcelona Tech to study the 2D velocity fields in the vicinity of a grate inlet. We used a platform to test grate inlets capacity with dimensions of 5.5 m long and 4 m wide allowing a zone of useful study of 5.5m x 3m, where the width is similar of the urban road lane. The platform allows you to modify the longitudinal slopes from 0% to 10% and transversal slope from 0% to 4%. Flow rates can arrive to 200 l/s. In addition a high resolution camera with 1280 x 1024 pixels resolution with maximum speed of 488 frames per second was used. A novel technique using particle image velocimetry to measure surface flow velocities has been developed and validated with the experimental data from the grate inlets capacity. In this case, the proposed methodology can become a useful tools to understand the velocity fields of the flow approaching the inlet where the traditional measuring equipment have serious problems and limitations. References DigiFlow User Guide. (2012), (June). Russo, B., Gómez, M., & Tellez, J. (2013). Methodology to Estimate the Hydraulic Efficiency of Nontested Continuous Transverse Grates. Journal of Irrigation and Drainage Engineering, 139(10), 864-871. doi:10.1061/(ASCE)IR.1943-4774.0000625 Teresa Vila (1), Jackson Tellez (1), Jesus Maria Sanchez (2), Laura Sotillos (1), Margarita Diez (3, 1), and J., & (1), M. R. (2014). Diffusion in fractal wakes and convective thermoelectric flows. Geophysical Research Abstracts - EGU General Assembly 2014

  3. Reconstruction of Sub-Surface Velocities from Satellite Observations Using Iterative Self-Organizing Maps

    Science.gov (United States)

    Chapman, Christopher; Charantonis, Anastase

    2017-04-01

    A new method based on modified self-organizing maps is presented for the reconstruction of deep ocean current velocities from surface information provided by satellites. This method takes advantage of local correlations in the data-space to improve the accuracy of the reconstructed deep velocities. No assumptions regarding the structure of the water column, nor the underlying dynamics of the flow field, are made. Using satellite observations of surface velocity, sea-surface height and sea-surface temperature, as well as observations of the deep current velocity from autonomous Argo floats to train the map, we are able to reconstruct realistic high-resolution velocity fields at a depth of 1000m. Validation reveals promising results, with a speed root mean squared error of approximately 2.8cm/s, more than a factor of two smaller than competing methods, and direction errors consistently smaller than 30 degrees. The shortcomings of this method will be discussed, as well as recent work to extend the method to produce a fully 3D reconstruction of the interior temperature and velocity fields.

  4. Effect of airflow velocity on moisture exchange at surfaces of building materials

    DEFF Research Database (Denmark)

    Mortensen, Lone Hedegaard; Rode, Carsten; Peuhkuri, Ruut Hannele

    2006-01-01

    The moisture transfer between air and construction are affected of the boundary layer conditions close to the surface, which is influenced by the airflow patterns in the room. Therefore an investigation of the relation be-tween the surface resistance and the airflow velocity above a material samp...

  5. FLOW VELOCITY AND SURFACE TEMPERATURE EFFECTS ON CONVECTIVE HEAT TRANSFER COEFFICIENT FROM URBAN CANOPY SURFACES BY NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Sivaraja Subramania Pillai

    2013-01-01

    Full Text Available This study investigates the effect of flow velocity and building surface temperature effects on Convective Heat Transfer Coefficient (CHTC from urban building surfaces by numerical simulation. The thermal effects produced by geometrical and physical properties of urban areas generate a relatively differential heating and uncomfortable environment compared to rural regions called as Urban Heat Island (UHI phenomena. The urban thermal comfort is directly related to the CHTC from the urban canopy surfaces. This CHTC from urban canopy surfaces expected to depend upon the wind velocity flowing over the urban canopy surfaces, urban canopy configurations, building surface temperature etc. But the most influential parameter on CHTC has not been clarified yet. Urban canopy type experiments in thermally stratified wind tunnel have normally been used to study the heat transfer issues. But, it is not an easy task in wind tunnel experiments to evaluate local CHTC, which vary on individual canyon surfaces such as building roof, walls and ground. Numerical simulation validated by wind tunnel experiments can be an alternative for the prediction of CHTC from building surfaces in an urban area. In our study, wind tunnel experiments were conducted to validate the low-Reynolds-number k- ε model which was used for the evaluation of CHTC from surfaces. The calculated CFD results showed good agreement with experimental results. After this validation, the effects of flow velocity and building surface temperature effects on CHTC from urban building surfaces were investigated. It has been found that the change in velocity remarkably affects the CHTC from urban canopy surfaces and change in surface temperature has almost no effect over the CHTC from urban canopy surfaces.

  6. FLOW VELOCITY AND SURFACE TEMPERATURE EFFECTS ON CONVECTIVE HEAT TRANSFER COEFFICIENT FROM URBAN CANOPY SURFACES BY NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Sivaraja Subramania Pillai

    2013-06-01

    Full Text Available This study investigates the effect of flow velocity and building surface temperature effects on Convective Heat Transfer Coefficient (CHTC from urban building surfaces by numerical simulation. The thermal effects produced by geometrical and physical properties of urban areas generate a relatively differential heating and uncomfortable environment compared to rural regions called as Urban Heat Island (UHI phenomena. The urban thermal comfort is directly related to the CHTC from the urban canopy surfaces. This CHTC from urban canopy surfaces expected to depend upon the wind velocity flowing over the urban canopy surfaces, urban canopy configurations, building surface temperature etc. But the most influential parameter on CHTC has not been clarified yet. Urban canopy type experiments in thermally stratified wind tunnel have normally been used to study the heat transfer issues. But, it is not an easy task in wind tunnel experiments to evaluate local CHTC, which vary on individual canyon surfaces such as building roof, walls and ground. Numerical simulation validated by wind tunnel experiments can be an alternative for the prediction of CHTC from building surfaces in an urban area. In our study, wind tunnel experiments were conducted to validate the low-Reynolds-number k-ε model which was used for the evaluation of CHTC from surfaces. The calculated CFD results showed good agreement with experimental results. After this validation, the effects of flow velocity and building surface temperature effects on CHTC from urban building surfaces were investigated. It has been found that the change in velocity remarkably affects the CHTC from urban canopy surfaces and change in surface temperature has almost no effect over the CHTC from urban canopy surfaces.

  7. Efficiency of the WFIRST Coronagraphic Survey based on Precursory Radial Velocity Measurements

    Science.gov (United States)

    Dulz, Shannon D.; Crepp, Justin; Plavchan, Peter; Newman, Patrick; Stark, Christopher

    2018-01-01

    We present our results and ongoing work studying how ground-based radial velocity systems can improve WFIRST planet detection and characterization efficiency. NASA's WFIRST mission will have the ability to characterize exoplanets via direct detection from space. By the time the mission is readied for launch in the mid 2020s, there will exist extensive data sets that provide precursory ground-based radial velocity measurements from a multitude of instruments. Such observations could presumably impact the efficiency of the high-contrast imaging system's ability to detect the signal of faint exoplanets, by providing time series measurements that both identify promising targets and establish orbital constraints for known planets. We are developing a suite of simulation tools to quantify the impact that such data sets will have on the mission. Populating nearby stars with synthetic planets based on the observed demographics of planetary systems, we simulate a ground-based radial velocity survey and WFIRST imaging follow-up.

  8. Technical Note: Surface water velocity observations from a camera: a case study on the Tiber River

    Science.gov (United States)

    Tauro, F.; Olivieri, G.; Petroselli, A.; Porfiri, M.; Grimaldi, S.

    2014-10-01

    Monitoring surface water velocity during flood events is a challenging task. Techniques based on deploying instruments in the flow are often unfeasible due to high velocity and abundant sediment transport. A low-cost and versatile technology that provides continuous and automatic observations is still not available. LSPIV (large scale particle imaging velocimetry) is a promising approach to tackle these issues. Such technique consists of developing surface water velocity maps analyzing video frame sequences recorded with a camera. In this technical brief, we implement a novel LSPIV experimental apparatus to observe a flood event in the Tiber river at a cross-section located in the center of Rome, Italy. We illustrate results from three tests performed during the hydrograph flood peak and recession limb for different illumination and weather conditions. The obtained surface velocity maps are compared to the rating curve velocity and to benchmark velocity values. Experimental findings confirm the potential of the proposed LSPIV implementation in aiding research in natural flow monitoring.

  9. A prototype of radar-drone system for measuring the surface flow velocity at river sites and discharge estimation

    Science.gov (United States)

    Moramarco, Tommaso; Alimenti, Federico; Zucco, Graziano; Barbetta, Silvia; Tarpanelli, Angelica; Brocca, Luca; Mezzanotte, Paolo; Rosselli, Luca; Orecchini, Giulia; Virili, Marco; Valigi, Paolo; Ciarfuglia, Thomas; Pagnottelli, Stefano

    2015-04-01

    , altimeter, camera) and artificial intelligence. Finally it has more than 0.3 kg payload that can be used for further instruments. With respect to the conventional approach, that uses radar sensors on fixed locations, the system prototype composed of drone and Doppler radar is more flexible and would allow carrying out velocity measurements obtaining the whole transverse surface velocity profile during high flow and for inaccessible river sites as well. This information represents the boundary condition of the entropy model (Moramarco et al. 2004) able to turn the surface velocity in discharge, known the geometry of the river site. Nowadays the prototype is being implemented and the Doppler radar sensor is tested in a static way, i.e. the flow velocity accuracy is determined in real-case situations by comparing the sensor output with that of conventional instruments. The first flying test is planned shortly in some river sites of Tiber River in central Italy and based on the surface velocity survey the capability of the radar-drone prototype will be tested and the benefit in discharge assessment by using the entropy model will be verified. Alimenti, F., Placentino, F., Battistini, A., Tasselli, G., Bernardini, W., Mezzanotte, P., Rascio, D., Palazzari, V., Leone, S., Scarponi, A., Porzi, N., Comez, M. and Roselli, L. (2007). "A Low-Cost 24GHz Doppler Radar Sensor for Traffic Monitoring Implemented in Standard Discrete-Component Technology". Proceedings of the 2007 European Radar Conference (EuRAD 2007), pp. 162-165, Munich, Germany, 10-12 October 2007 Chiu, C. L. (1987). "Entropy and probability concepts in hydraulics". J. Hydr. Engrg., ASCE, 113(5), 583-600. Moramarco, T., Saltalippi, C., Singh, V.P.(2004). "Estimation of mean velocity in natural channels based on Chiu's velocity distribution equation", Journal of Hydrologic Engineering, 9 (1), pp. 42-50

  10. Laser photoacoustic technique for ultrasonic surface acoustic wave velocity evaluation on porcelain

    Science.gov (United States)

    Qian, K.; Tu, S. J.; Gao, L.; Xu, J.; Li, S. D.; Yu, W. C.; Liao, H. H.

    2016-10-01

    A laser photoacoustic technique has been developed to evaluate the surface acoustic wave (SAW) velocity of porcelain. A Q-switched Nd:YAG laser at 1064 nm was focused by a cylindrical lens to initiate broadband SAW impulses, which were detected by an optical fiber interferometer with high spatial resolution. Multiple near-field surface acoustic waves were observed on the sample surface at various locations along the axis perpendicular to the laser line source as the detector moved away from the source in the same increments. The frequency spectrum and dispersion curves were obtained by operating on the recorded waveforms with cross-correlation and FFT. The SAW phase velocities of the porcelain of the same source are similar while they are different from those of different sources. The marked differences of Rayleigh phase velocities in our experiment suggest that this technique has the potential for porcelain identification.

  11. Slope–velocity equilibrium and evolution of surface roughness on a stony hillslope

    Directory of Open Access Journals (Sweden)

    M. A. Nearing

    2017-06-01

    Full Text Available Slope–velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and surface morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow rate independent of slope gradient. This study tests this hypothesis under controlled conditions. Artificial rainfall was applied to 2 m by 6 m plots at 5, 12, and 20 % slope gradients. A series of simulations were made with two replications for each treatment with measurements of runoff rate, velocity, rock cover, and surface roughness. Velocities measured at the end of each experiment were a unique function of discharge rates, independent of slope gradient or rainfall intensity. Physical surface roughness was greater at steeper slopes. The data clearly showed that there was no unique hydraulic coefficient for a given slope, surface condition, or rainfall rate, with hydraulic roughness greater at steeper slopes and lower intensities. This study supports the hypothesis of slope–velocity equilibrium, implying that use of hydraulic equations, such as Chezy and Manning, in hillslope-scale runoff models is problematic because the coefficients vary with both slope and rainfall intensity.

  12. Velocity dependence of vestibular information for postural control on tilting surfaces

    Science.gov (United States)

    Kluzik, JoAnn; Hlavacka, Frantisek

    2016-01-01

    Vestibular information is known to be important for postural stability on tilting surfaces, but the relative importance of vestibular information across a wide range of surface tilt velocities is less clear. We compared how tilt velocity influences postural orientation and stability in nine subjects with bilateral vestibular loss and nine age-matched, control subjects. Subjects stood on a force platform that tilted 6 deg, toes-up at eight velocities (0.25 to 32 deg/s), with and without vision. Results showed that visual information effectively compensated for lack of vestibular information at all tilt velocities. However, with eyes closed, subjects with vestibular loss were most unstable within a critical tilt velocity range of 2 to 8 deg/s. Subjects with vestibular deficiency lost their balance in more than 90% of trials during the 4 deg/s condition, but never fell during slower tilts (0.25–1 deg/s) and fell only very rarely during faster tilts (16–32 deg/s). At the critical velocity range in which falls occurred, the body center of mass stayed aligned with respect to the surface, onset of ankle dorsiflexion was delayed, and there was delayed or absent gastrocnemius inhibition, suggesting that subjects were attempting to actively align their upper bodies with respect to the moving surface instead of to gravity. Vestibular information may be critical for stability at velocities of 2 to 8 deg/s because postural sway above 2 deg/s may be too fast to elicit stabilizing responses through the graviceptive somatosensory system, and postural sway below 8 deg/s may be too slow for somatosensory-triggered responses or passive stabilization from trunk inertia. PMID:27486101

  13. Estimation of the surface velocity of debris flow with computer-based spatial filtering.

    Science.gov (United States)

    Uddin, M S; Inaba, H; Itakura, Y; Kasahara, M

    1998-09-10

    A computer-based spatial-filtering velocimeter to measure the surface velocity of natural debris flow is described. This is a simple and interesting technique implemented with a spatial filter constructed as a software program that processes the video image of debris flow instead of a hardware implementation. The surface velocity of the debris flow at the Mt. Yakedake Volcano, Japan, was estimated by this computer-based spatial-filtering method, and the results were compared with those obtained by a hardware-based spatial-filtering method. Computer-based spatial filtering has the important advantage of a capability for tuning the spatial-filter parameters to the target flow.

  14. Towards an optimal sampling of peculiar velocity surveys for Wiener Filter reconstructions

    Science.gov (United States)

    Sorce, Jenny G.; Hoffman, Yehuda; Gottlöber, Stefan

    2017-06-01

    The Wiener Filter (WF) technique enables the reconstruction of density and velocity fields from observed radial peculiar velocities. This paper aims at identifying the optimal design of peculiar velocity surveys within the WF framework. The prime goal is to test the dependence of the reconstruction quality on the distribution and nature of data points. Mock data sets, extending to 250 h-1 Mpc, are drawn from a constrained simulation that mimics the local Universe to produce realistic mock catalogues. Reconstructed fields obtained with these mocks are compared to the reference simulation. Comparisons, including residual distributions, cell-to-cell and bulk velocities, imply that the presence of field data points is essential to properly measure the flows. The fields reconstructed from mocks that consist only of galaxy cluster data points exhibit poor-quality bulk velocities. In addition, the reconstruction quality depends strongly on the grouping of individual data points into single points to suppress virial motions in high-density regions. Conversely, the presence of a Zone of Avoidance hardly affects the reconstruction. For a given number of data points, a uniform sample does not score any better than a sample with decreasing number of data points with the distance. The best reconstructions are obtained with a grouped survey containing field galaxies: assuming no error, they differ from the simulated field by less than 100 km s-1 up to the extreme edge of the catalogues or up to a distance of three times the mean distance of data points for non-uniform catalogues. The overall conclusions hold when errors are added.

  15. Influence of filtration velocity on DON variation in BAF for micropolluted surface water treatment.

    Science.gov (United States)

    Ma, Teng-Fei; Chen, You-Peng; Kang, Jia; Gao, Xu; Guo, Jin-Song; Fang, Fang; Zhang, Xiao-Tian

    2016-12-01

    Biological aerated filters (BAFs) are widely used for the treatment of micropolluted surface water. However, the biological process produces dissolved organic nitrogen (DON), which, as precursors of nitrogenous disinfection by-products, pose potential threats to drinking water safety. Therefore, to control DON in BAF effluent, it is necessary to study the influence of BAF operation parameters on DON production. In this study, the influence of filtration velocity in a BAF on DON production was investigated. Under different filtration velocity (0.5, 2, and 4 m/h) conditions, profiles of DON concentrations along the media layer were measured. The profile at a filtration velocity of 0.5 m/h showed a decreasing trend, and the ones under filtration velocities of 2 and 4 m/h fluctuated in a small range (from 0.1 to 0.4 mg/L). Moreover, the relatively high filtration velocities of 2 and 4 m/h resulted in a lower level of DON concentration. Additionally, 3D excitation-emission matrix fluorescence spectroscopy was used to characterize DON. It is found that the patterns of DON at a relatively high filtration velocity condition (4 m/h) were obviously different from the ones under low filtration velocity conditions (0.5 and 2 m/h).

  16. Shear wave velocity structure in North America from large-scale waveform inversions of surface waves

    Science.gov (United States)

    Alsina, D.; Woodward, R.L.; Snieder, R.K.

    1996-01-01

    A two-step nonlinear and linear inversion is carried out to map the lateral heterogeneity beneath North America using surface wave data. The lateral resolution for most areas of the model is of the order of several hundred kilometers. The most obvious feature in the tomographic images is the rapid transition between low velocities in the technically active region west of the Rocky Mountains and high velocities in the stable central and eastern shield of North America. The model also reveals smaller-scale heterogeneous velocity structures. A high-velocity anomaly is imaged beneath the state of Washington that could be explained as the subducting Juan de Fuca plate beneath the Cascades. A large low-velocity structure extends along the coast from the Mendocino to the Rivera triple junction and to the continental interior across the southwestern United States and northwestern Mexico. Its shape changes notably with depth. This anomaly largely coincides with the part of the margin where no lithosphere is consumed since the subduction has been replaced by a transform fault. Evidence for a discontinuous subduction of the Cocos plate along the Middle American Trench is found. In central Mexico a transition is visible from low velocities across the Trans-Mexican Volcanic Belt (TMVB) to high velocities beneath the Yucatan Peninsula. Two elongated low-velocity anomalies beneath the Yellowstone Plateau and the eastern Snake River Plain volcanic system and beneath central Mexico and the TMVB seem to be associated with magmatism and partial melting. Another low-velocity feature is seen at depths of approximately 200 km beneath Florida and the Atlantic Coastal Plain. The inversion technique used is based on a linear surface wave scattering theory, which gives tomographic images of the relative phase velocity perturbations in four period bands ranging from 40 to 150 s. In order to find a smooth reference model a nonlinear inversion based on ray theory is first performed. After

  17. Resolution potential of surface wave phase velocity measurements at small arrays

    Science.gov (United States)

    Bodin, Thomas; Maupin, Valérie

    2008-02-01

    The deployment of temporary arrays of broadband seismological stations over dedicated targets is common practice. Measurement of surface wave phase velocity across a small array and its depth-inversion gives us information about the structure below the array which is complementary to the information obtained from body-wave analysis. The question is however: what do we actually measure when the array is much smaller than the wave length, and how does the measured phase velocity relates to the real structure below the array? We quantify this relationship by performing a series of numerical simulations of surface wave propagation in 3-D structures and by measuring the apparent phase velocity across the array on the synthetics. A principal conclusion is that heterogeneities located outside the array can map in a complex way onto the phase velocities measured by the array. In order to minimize this effect, it is necessary to have a large number of events and to average measurements from events well-distributed in backazimuth. A second observation is that the period of the wave has a remarkably small influence on the lateral resolution of the measurement, which is dominantly controlled by the size of the array. We analyse if the artefacts created by heterogeneities can be mistaken for azimuthal variations caused by anisotropy. We also show that if the amplitude of the surface waves can be measured precisely enough, phase velocities can be corrected and the artefacts which occur due to reflections and diffractions in 3-D structures greatly reduced.

  18. The MASSIVE survey - VIII. Stellar velocity dispersion profiles and environmental dependence of early-type galaxies

    Science.gov (United States)

    Veale, Melanie; Ma, Chung-Pei; Greene, Jenny E.; Thomas, Jens; Blakeslee, John P.; Walsh, Jonelle L.; Ito, Jennifer

    2018-02-01

    We measure the radial profiles of the stellar velocity dispersions, σ(R), for 90 early-type galaxies (ETGs) in the MASSIVE survey, a volume-limited integral-field spectroscopic (IFS) galaxy survey targeting all northern-sky ETGs with absolute K-band magnitude MK galaxies with sufficient radial coverage to determine γouter we find 36 per cent to have rising outer dispersion profiles, 30 per cent to be flat within the uncertainties and 34 per cent to be falling. The fraction of galaxies with rising outer profiles increases with M* and in denser galaxy environment, with 10 of the 11 most massive galaxies in our sample having flat or rising dispersion profiles. The strongest environmental correlations are with local density and halo mass, but a weaker correlation with large-scale density also exists. The average γouter is similar for brightest group galaxies, satellites and isolated galaxies in our sample. We find a clear positive correlation between the gradients of the outer dispersion profile and the gradients of the velocity kurtosis h4. Altogether, our kinematic results suggest that the increasing fraction of rising dispersion profiles in the most massive ETGs are caused (at least in part) by variations in the total mass profiles rather than in the velocity anisotropy alone.

  19. Hydraulics and drones: observations of water level, bathymetry and water surface velocity from Unmanned Aerial Vehicles

    DEFF Research Database (Denmark)

    Bandini, Filippo

    profilers (ADCPs). For these reasons, water speed observations have been traditionally challenging, especially in difficult-to-access environments. Conversely, UAV-borne observations open up the possibility of measuring water speed over extended regions at a low cost. The 2D water surface velocity field...

  20. Surface ice flow velocity and tide retrieval of the amery ice shelf using precise point positioning

    DEFF Research Database (Denmark)

    Zhang, X.H.; Andersen, Ole Baltazar

    2006-01-01

    Five days of continuous GPS observation data were collected in the frontal zone of the Amery ice shelf and subsequently post-processed using precise point position (PPP) technology based on precise orbit and clock products from the International GNSS service. The surface ice flow velocity of the ...

  1. A Numerical Method for Predicting Rayleigh Surface Wave Velocity in Anisotropic Crystals (Postprint)

    Science.gov (United States)

    2017-09-05

    crystal elastic moduli from literature . It was found to be very robust and efficient in calculating RSW velocity curves in all cases. 15. SUBJECT...crystal sample. The algorithm was tested with crystal symmetries and single crystal elastic moduli from literature . It was found to be very robust and...using them in the context of materials characterization. Another important concept in the analysis of surface waves is the surface impedance matrix

  2. Direct ambient noise tomography for 3-D near surface shear velocity structure: methodology and applications

    Science.gov (United States)

    Yao, H.; Fang, H.; Li, C.; Liu, Y.; Zhang, H.; van der Hilst, R. D.; Huang, Y. C.

    2014-12-01

    Ambient noise tomography has provided essential constraints on crustal and uppermost mantle shear velocity structure in global seismology. Recent studies demonstrate that high frequency (e.g., ~ 1 Hz) surface waves between receivers at short distances can be successfully retrieved from ambient noise cross-correlation and then be used for imaging near surface or shallow crustal shear velocity structures. This approach provides important information for strong ground motion prediction in seismically active area and overburden structure characterization in oil and gas fields. Here we propose a new tomographic method to invert all surface wave dispersion data for 3-D variations of shear wavespeed without the intermediate step of phase or group velocity maps.The method uses frequency-dependent propagation paths and a wavelet-based sparsity-constrained tomographic inversion. A fast marching method is used to compute, at each period, surface wave traveltimes and ray paths between sources and receivers. This avoids the assumption of great-circle propagation that is used in most surface wave tomographic studies, but which is not appropriate in complex media. The wavelet coefficients of the velocity model are estimated with an iteratively reweighted least squares (IRLS) algorithm, and upon iterations the surface wave ray paths and the data sensitivity matrix are updated from the newly obtained velocity model. We apply this new method to determine the 3-D near surface wavespeed variations in the Taipei basin of Taiwan, Hefei urban area and a shale and gas production field in China using the high-frequency interstation Rayleigh wave dispersion data extracted from ambient noisecross-correlation. The results reveal strong effects of off-great-circle propagation of high-frequency surface waves in these regions with above 30% shear wavespeed variations. The proposed approach is more efficient and robust than the traditional two-step surface wave tomography for imaging complex

  3. The SAMI Galaxy Survey: energy sources of the turbulent velocity dispersion in spatially resolved local star-forming galaxies

    Science.gov (United States)

    Zhou, Luwenjia; Federrath, Christoph; Yuan, Tiantian; Bian, Fuyan; Medling, Anne M.; Shi, Yong; Bland-Hawthorn, Joss; Bryant, Julia J.; Brough, Sarah; Catinella, Barbara; Croom, Scott M.; Goodwin, Michael; Goldstein, Gregory; Green, Andrew W.; Konstantopoulos, Iraklis S.; Lawrence, Jon S.; Owers, Matt S.; Richards, Samuel N.; Sanchez, Sebastian F.

    2017-10-01

    We investigate the energy sources of random turbulent motions of ionized gas from H α emission in eight local star-forming galaxies from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. These galaxies satisfy strict pure star-forming selection criteria to avoid contamination from active galactic nuclei (AGNs) or strong shocks/outflows. Using the relatively high spatial and spectral resolution of SAMI, we find that - on sub-kpc scales, our galaxies display a flat distribution of ionized gas velocity dispersion as a function of star formation rate (SFR) surface density. A major fraction of our SAMI galaxies shows higher velocity dispersion than predictions by feedback-driven models, especially at the low SFR surface density end. Our results suggest that additional sources beyond star formation feedback contribute to driving random motions of the interstellar medium in star-forming galaxies. We speculate that gravity, galactic shear and/or magnetorotational instability may be additional driving sources of turbulence in these galaxies.

  4. Red Optical Planet Survey: A radial velocity search for low mass M dwarf planets

    Directory of Open Access Journals (Sweden)

    Minniti D.

    2013-04-01

    Full Text Available We present radial velocity results from our Red Optical Planet Survey (ROPS, aimed at detecting low-mass planets orbiting mid-late M dwarfs. The ∼10 ms−1 precision achieved over 2 consecutive nights with the MIKE spectrograph at Magellan Clay is also found on week long timescales with UVES at VLT. Since we find that UVES is expected to attain photon limited precision of order 2 ms−1 using our novel deconvolution technique, we are limited only by the (≤10 ms−1 stability of atmospheric lines. Rocky planet frequencies of η⊕ = 0.3−0.7 lead us to expect high planet yields, enabling determination of η⊕ for the uncharted mid-late M dwarfs with modest surveys.

  5. Dual universe and hyperboloidal relative velocity surface arising from extended special relativity

    Science.gov (United States)

    Hill, James M.; Cox, Barry J.

    2014-12-01

    In two recent and completely independent articles (Hill and Cox in Proc R Soc A 468:4174, 2012; Vieira in Rev Bras Ensino F's 34(3):1-15, 2012), the authors propose an extension of the Lorentz transformations of special relativity which are applicable to velocities in excess of the speed of light and do not involve the need to introduce imaginary quantities which are difficult to reconcile with everyday experience. These independent derivations, obtained from entirely distinct perspectives, mean that there is now some commonality of agreement in the basic equations underlying superluminal motion. One consequence of the new theories is that the standard special relativity formula for the addition of relative velocities also applies for velocities in excess of the speed of light. The new theories are based on the assumption that for any two inertial frames separated by an infinite relative velocity, the product of the two measured velocities for the same particle must necessarily be the square of the speed of light. Here, we amplify the major physical consequences embodied in the theory, including the surprising and novel idea of the co-existence of two "worlds", such that in a subluminal world, everything is travelling with speeds less than the speed of light, while in the superluminal world, everything is travelling with speeds greater than the speed of light. We also establish the remarkable result that the reciprocal surface for the relative velocity formula can be re-orientated as a fully axially symmetric hyperboloidal surface, the full physical implications of which are not altogether transparent.

  6. Velocity gradients in the Earth's upper mantle: insights from higher mode surface waves

    Science.gov (United States)

    Fishwick, Stewart; Maupin, Valerie; Afonso, Juan Carlos

    2016-04-01

    The majority of seismic tomographic models of the uppermost mantle beneath Precambrian regions show a positive velocity gradient from the Moho to depths of around 100 km. It is becoming increasingly well recognised that this gradient is not readily compatible with simple models of a craton with constant composition and a steady-state geotherm and more complex compositional variations are invoked to explain this feature. At these depths most of the models are dominated by data from fundamental mode surface waves, and the combination of the sensitivity kernels alongside the choice of model parameterisation means that the velocity gradient could be an artefact of the particular inversion. Indeed, recent work using thermodynamically consistent velocity models suggests that in some cases there is not a requirement of this style of gradient. We investigate this aspect of the mantle structure further by returning to the Sa phase. This phase can be considered as the build up of a wave packet due to the overlapping group velocities of higher modes at periods of around 8 - 30 s. Using the Australian shield as a test-case we compare waveforms built from three different styles of velocity model. Firstly, the 1D model AU3 (Gaherty & Jordan, 1995) which did incorporate the Sa phase as part of the waveform in their modelling. Secondly, recent tomographic models of the Australian continent are used, which include no a priori information from the phase. Thirdly, a thermodynamically consistent velocity model that fits the broad dispersion characteristics of the tomography is tested. Finally, these synthetic waveforms are compared to real data crossing the Australian shield. The results illustrate small, but clear, variations in waveform dependent on the velocity structure. Complicating factors in any analysis involve the importance of having good knowledge of the crustal structure and a very accurate source depth (particularly if this is similar to the average crustal thickness).

  7. Effect of ion excape velocity and conversion surface material on H- production

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kenneth F [Los Alamos National Laboratory; Tarvainen, Olli A [Los Alamos National Laboratory; Geros, E. [Los Alamos National Laboratory; Stelzer, J. [Los Alamos National Laboratory; Rouleau, G. [Los Alamos National Laboratory; Kalvas, T. [UNIV OF JYVASKYLA; Komppula, J. [UNIV OF JYASKYLA; Carmichael, J. [ORNL

    2010-10-05

    According to generally accepted models surface production of negative ions depends on ion escape velocity and work function of the surface. We have conducted an experimental study addressing the role of the ion escape velocity on H{sup -} production. A converter-type ion source at Los Alamos Neutron Science Center was employed for the experiment. The ion escape velocity was changed by varying the bias voltage of the converter electrode. It was observed that due to enhanced stripping of H{sup -} no direct gain of extracted beam current can be achieved by increasing the converter voltage. At the same time the conversion efficiency of H{sup -} was observed to vary with converter voltage and follow the existing theories in qualitative manner. We discuss the role of surface material on H{sup -} formation probability and present calculations predicting relative H{sup -} yields from different cesiated surfaces. These calculations are compared with experimental observations from different types of H{sup -} ion sources. The effects caused by varying cesium coverage are also discussed. Finally, we present a novel idea of utilizing materials exhibiting so-called negative electron affinity in H{sup -}/D{sup -} production under UV-light exposure.

  8. The lift-off velocity on the surface of an arbitrary body

    Science.gov (United States)

    Van wal, S.; Scheeres, D. J.

    2016-05-01

    An expression is developed for the velocity at which a particle, moving tangentially on the surface of a body with an arbitrary shape, rotation, and gravitational field, will lift off from that surface and enter orbit. The osculating departure plane in which this lift-off motion occurs is defined by the net particle acceleration and the desired lift-off direction. The body surface is approximated within this plane, at the departure point, with some radius and center of curvature, allowing for a universal, frame-independent lift-off velocity expression. Applying the geometry of plane-ellipsoid intersections, we perform a validation of the full lift-off velocity expression on a number of rotating ellipsoids. Finally, we derive a limit expression for the case of lift-off from a rotating plane, and compare this with the results on curved bodies. This theory has numerous applications to lander/rover surface mobility operations on asteroids, comets, and small moons, as well as to geophysical processes encountered on these bodies.

  9. EFFECTS OF A SAND RUNNING SURFACE ON THE KINEMATICS OF SPRINTING AT MAXIMUM VELOCITY

    Directory of Open Access Journals (Sweden)

    P E Alcaraz

    2011-05-01

    Full Text Available Performing sprints on a sand surface is a common training method for improving sprint-specific strength. For maximum specificity of training the athlete’s movement patterns during the training exercise should closely resemble those used when performing the sport. The aim of this study was to compare the kinematics of sprinting at maximum velocity on a dry sand surface to the kinematics of sprinting on an athletics track. Five men and five women participated in the study, and flying sprints over 30 m were recorded by video and digitized using biomechanical analysis software. We found that sprinting on a sand surface was substantially different to sprinting on an athletics track. When sprinting on sand the athletes tended to ‘sit’ during the ground contact phase of the stride. This action was characterized by a lower centre of mass, a greater forward lean in the trunk, and an incomplete extension of the hip joint at take-off. We conclude that sprinting on a dry sand surface may not be an appropriate method for training the maximum velocity phase in sprinting. Although this training method exerts a substantial overload on the athlete, as indicated by reductions in running velocity and stride length, it also induces detrimental changes to the athlete’s running technique which may transfer to competition sprinting.

  10. S-Wave Velocity Across Central Mexico Using High Resolution Surface Wave Tomography

    Science.gov (United States)

    Iglesias, A.; Clayton, R. W.; Pérez-Campos, X.; Singh, S. K.; Pacheco, J. F.; García, D.; Valdés-González, C.

    2008-12-01

    The shear wave velocity structure across central Mexico is determined by surface wave dispersion from a dense linear seismic experiment "Mesoamerican Subduction Experiment" (MASE). MASE consisted of 100 portable broadband stations deployed along a line crossing Central Mexico from the Pacific Coast to almost the Gulf of Mexico. Regional records were used to obtain Rayleigh-wave group velocity maps for periods from 5 to 50 s and they show a dramatic variation of velocity (~40%), especially for periods larger of 20 s. Local dispersion curves were reconstructed for each station and inverted to find S-wave velocity by using a simulated annealing algorithm. The results, from inversion, show a significant change, particularly in the lower crust, between the backarc, volcanic arc and forearc regions. The crust in the forearc is thicker and faster than the backarc region. Just below the active Trans Mexican Volcanic Belt (TMVB) (300 km from the coast) is presently a low velocity spot (~3.4 km/s) suggesting presence of anomalous material (probably related to a mantle wedge) as deep as 50 km. The results also show a poorly resolved slab and wedge which correspond to the ones in a model reported recently. The results are supported with consistency checks and resolution tests.

  11. Efficient scheduling of astronomical observations. Application to the CARMENES radial-velocity survey

    Science.gov (United States)

    Garcia-Piquer, A.; Morales, J. C.; Ribas, I.; Colomé, J.; Guàrdia, J.; Perger, M.; Caballero, J. A.; Cortés-Contreras, M.; Jeffers, S. V.; Reiners, A.; Amado, P. J.; Quirrenbach, A.; Seifert, W.

    2017-08-01

    Context. Targeted spectroscopic exoplanet surveys face the challenge of maximizing their planet detection rates by means of careful planning. For a large planet survey, the number of possible observation combinations, I.e., the sequence of observations night after night, both in total time and amount of targets, is enormous. Aims: Sophisticated scheduling tools and the improved understanding of the exoplanet population are employed to investigate an efficient and optimal way to plan the execution of observations. This is applied to the CARMENES instrument, which is an optical and infrared high-resolution spectrograph that has started a survey of about 300 M-dwarf stars in search of terrestrial exoplanets. Methods: We used evolutionary computation techniques to create an automatic scheduler that minimizes the idle periods of the telescope and distributes the observations among all the targets using configurable criteria. We simulated the case of the CARMENES survey with a realistic sample of targets, and we estimated the efficiency of the planning tool both in terms of telescope operations and planet detection. Results: Our scheduling simulations produce plans that use about 99% of the available telescope time (including overheads) and optimally distribute the observations among the different targets. Under such conditions, and using current planet statistics, the optimized plan using this tool should allow the CARMENES survey to discover about 65% of the planets with radial-velocity semi-amplitudes greater than 1 ms-1 when considering only photon noise. Conclusions: The simulations using our scheduling tool show that it is possible to optimize the survey planning by minimizing idle instrument periods and fulfilling the science objectives in an efficient manner to maximize the scientific return.

  12. On measuring surface wave phase velocity from station–station cross-correlation of ambient signal

    DEFF Research Database (Denmark)

    Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie

    2012-01-01

    We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one...... method involves the time-domain cross-correlation of signal recorded at different stations; the other is based on frequency-domain cross-correlation, and requires finding the zero-crossings of the real part of the cross-correlation spectrum. Furthermore, the time-domain method, as implemented here......, writing out explicitly the relationships between the surface wave Green’s function, ambient-noise cross-correlation and phase and group velocities....

  13. Space Debris Surfaces - Probability of no penetration versus impact velocity and obliquity

    Science.gov (United States)

    Elfer, N.; Meibaum, R.; Olsen, G.

    1992-01-01

    A collection of computer codes called Space Debris Surfaces (SD-SURF), have been developed to assist in the design and analysis of space debris protection systems. An SD-SURF analysis will show which obliquities and velocities are most likely to cause a penetration to help the analyst select a shield design best suited to the predominant penetration mechanism. Examples of the interaction between space vehicle geometry, the space debris environment, and the penetration and critical damage ballistic limit surfaces of the shield under consideration are presented.

  14. Spectral analysis of surface waves method to assess shear wave velocity within centrifuge models

    Science.gov (United States)

    Murillo, Carol Andrea; Thorel, Luc; Caicedo, Bernardo

    2009-06-01

    The method of the spectral analysis of surface waves (SASW) is tested out on reduced scale centrifuge models, with a specific device, called the mini Falling Weight, developed for this purpose. Tests are performed on layered materials made of a mixture of sand and clay. The shear wave velocity VS determined within the models using the SASW is compared with the laboratory measurements carried out using the bender element test. The results show that the SASW technique applied to centrifuge testing is a relevant method to characterize VS near the surface.

  15. Anisotropic S-wave velocity structure from joint inversion of surface wave group velocity dispersion: A case study from India

    Science.gov (United States)

    Mitra, S.; Dey, S.; Siddartha, G.; Bhattacharya, S.

    2016-12-01

    We estimate 1-dimensional path average fundamental mode group velocity dispersion curves from regional Rayleigh and Love waves sampling the Indian subcontinent. The path average measurements are combined through a tomographic inversion to obtain 2-dimensional group velocity variation maps between periods of 10 and 80 s. The region of study is parametrised as triangular grids with 1° sides for the tomographic inversion. Rayleigh and Love wave dispersion curves from each node point is subsequently extracted and jointly inverted to obtain a radially anisotropic shear wave velocity model through global optimisation using Genetic Algorithm. The parametrization of the model space is done using three crustal layers and four mantle layers over a half-space with varying VpH , VsV and VsH. The anisotropic parameter (η) is calculated from empirical relations and the density of the layers are taken from PREM. Misfit for the model is calculated as a sum of error-weighted average dispersion curves. The 1-dimensional anisotropic shear wave velocity at each node point is combined using linear interpolation to obtain 3-dimensional structure beneath the region. Synthetic tests are performed to estimate the resolution of the tomographic maps which will be presented with our results. We envision to extend this to a larger dataset in near future to obtain high resolution anisotrpic shear wave velocity structure beneath India, Himalaya and Tibet.

  16. The boundary condition for vertical velocity and its interdependence with surface gas exchange

    Science.gov (United States)

    Kowalski, Andrew S.

    2017-07-01

    The law of conservation of linear momentum is applied to surface gas exchanges, employing scale analysis to diagnose the vertical velocity (w) in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E) and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = E/ρ. This is true even right down at the surface where the boundary condition is w|0 = E/ρ|0 (where w|0 and ρ|0 represent the vertical velocity and density of air at the surface). This Stefan flow velocity implies upward transport of a non-diffusive nature that is a general feature of the troposphere but is of particular importance at the surface, where it assists molecular diffusion with upward gas migration (of H2O, for example) but opposes that of downward-diffusing species like CO2 during daytime. The definition of flux-gradient relationships (eddy diffusivities) requires rectification to exclude non-diffusive transport, which does not depend on scalar gradients. At the microscopic scale, the role of non-diffusive transport in the process of evaporation from inside a narrow tube - with vapour transport into an overlying, horizontal airstream - was described long ago in classical mechanics and is routinely accounted for by chemical engineers, but has been neglected by scientists studying stomatal conductance. Correctly accounting for non-diffusive transport through stomata, which can appreciably reduce net CO2 transport and marginally boost that of water vapour, should improve characterisations of ecosystem and plant functioning.

  17. The boundary condition for vertical velocity and its interdependence with surface gas exchange

    Directory of Open Access Journals (Sweden)

    A. S. Kowalski

    2017-07-01

    Full Text Available The law of conservation of linear momentum is applied to surface gas exchanges, employing scale analysis to diagnose the vertical velocity (w in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = E/ρ. This is true even right down at the surface where the boundary condition is w|0 = E/ρ|0 (where w|0 and ρ|0 represent the vertical velocity and density of air at the surface. This Stefan flow velocity implies upward transport of a non-diffusive nature that is a general feature of the troposphere but is of particular importance at the surface, where it assists molecular diffusion with upward gas migration (of H2O, for example but opposes that of downward-diffusing species like CO2 during daytime. The definition of flux–gradient relationships (eddy diffusivities requires rectification to exclude non-diffusive transport, which does not depend on scalar gradients. At the microscopic scale, the role of non-diffusive transport in the process of evaporation from inside a narrow tube – with vapour transport into an overlying, horizontal airstream – was described long ago in classical mechanics and is routinely accounted for by chemical engineers, but has been neglected by scientists studying stomatal conductance. Correctly accounting for non-diffusive transport through stomata, which can appreciably reduce net CO2 transport and marginally boost that of water vapour, should improve characterisations of ecosystem and plant functioning.

  18. Improved measurements of mean sea surface velocity in the Nordic Seas from synthetic aperture radar

    Science.gov (United States)

    Wergeland Hansen, Morten; Johnsen, Harald; Engen, Geir; Øie Nilsen, Jan Even

    2017-04-01

    The warm and saline surface Atlantic Water (AW) flowing into the Nordic Seas across the Greenland-Scotland ridge transports heat into the Arctic, maintaining the ice-free oceans and regulating sea-ice extent. The AW influences the region's relatively mild climate and is the northern branch of the global thermohaline overturning circulation. Heat loss in the Norwegian Sea is key for both heat transport and deep water formation. In general, the ocean currents in the Nordic Seas and the North Atlantic Ocean is a complex system of topographically steered barotropic and baroclinic currents of which the wind stress and its variability is a driver of major importance. The synthetic aperture radar (SAR) Doppler centroid shift has been demonstrated to contain geophysical information about sea surface wind, waves and current at an accuracy of 5 Hz and pixel spacing of 3.5 - 9 × 8 km2. This corresponds to a horizontal surface velocity of about 20 cm/s at 35° incidence angle. The ESA Prodex ISAR project aims to implement new and improved SAR Doppler shift processing routines to enable reprocessing of the wide swath acquisitions available from the Envisat ASAR archive (2002-2012) at higher resolution and better accuracy than previously obtained, allowing combined use with Sentinel-1 and Radarsat-2 retrievals to build timeseries of the sea surface velocity in the Nordic Seas. Estimation of the geophysical Doppler shift from new SAR Doppler centroid shift retrievals will be demonstrated, addressing key issues relating to geometric (satellite orbit and attitude) and electronic (antenna mis-pointing) contributions and corrections. Geophysical Doppler shift retrievals from one month of data in January 2010 and the inverted surface velocity in the Nordic Seas are then addressed and compared to other direct and indirect estimates of the upper ocean current, in particular those obtained in the ESA GlobCurrent project.

  19. Near-surface shear-wave velocity measurements in unlithified sediment

    Science.gov (United States)

    Richards, B.T.; Steeples, D.; Miller, R.; Ivanov, J.; Peterie, S.; Sloan, S.D.; McKenna, J.R.

    2011-01-01

    S-wave velocity can be directly correlated to material stiffness and lithology making it a valuable physical property that has found uses in construction, engineering, and environmental projects. This study compares different methods for measuring S-wave velocities, investigating and identifying the differences among the methods' results, and prioritizing the different methods for optimal S-wave use at the U. S. Army's Yuma Proving Grounds YPG. Multichannel Analysis of Surface Waves MASW and S-wave tomography were used to generate S-wave velocity profiles. Each method has advantages and disadvantages. A strong signal-to-noise ratio at the study site gives the MASW method promising resolution. S-wave first arrivals are picked on impulsive sledgehammer data which were then used for the tomography process. Three-component downhole seismic data were collected in-line with a locking geophone, providing ground truth to compare the data and to draw conclusions about the validity of each data set. Results from these S-wave measurement techniques are compared with borehole seismic data and with lithology data from continuous samples to help ascertain the accuracy, and therefore applicability, of each method. This study helps to select the best methods for obtaining S-wave velocities for media much like those found in unconsolidated sediments at YPG. ?? 2011 Society of Exploration Geophysicists.

  20. Analysis shear wave velocity structure obtained from surface wave methods in Bornova, Izmir

    Energy Technology Data Exchange (ETDEWEB)

    Pamuk, Eren, E-mail: eren.pamuk@deu.edu.tr; Akgün, Mustafa, E-mail: mustafa.akgun@deu.edu.tr [Department of Geophysical Engineering, Dokuz Eylul University, Izmir (Turkey); Özdağ, Özkan Cevdet, E-mail: cevdet.ozdag@deu.edu.tr [Dokuz Eylul University Rectorate, Izmir (Turkey)

    2016-04-18

    Properties of the soil from the bedrock is necessary to describe accurately and reliably for the reduction of earthquake damage. Because seismic waves change their amplitude and frequency content owing to acoustic impedance difference between soil and bedrock. Firstly, shear wave velocity and depth information of layers on bedrock is needed to detect this changing. Shear wave velocity can be obtained using inversion of Rayleigh wave dispersion curves obtained from surface wave methods (MASW- the Multichannel Analysis of Surface Waves, ReMi-Refraction Microtremor, SPAC-Spatial Autocorrelation). While research depth is limeted in active source study, a passive source methods are utilized for deep depth which is not reached using active source methods. ReMi method is used to determine layer thickness and velocity up to 100 m using seismic refraction measurement systems.The research carried out up to desired depth depending on radius using SPAC which is utilized easily in conditions that district using of seismic studies in the city. Vs profiles which are required to calculate deformations in under static and dynamic loads can be obtained with high resolution using combining rayleigh wave dispersion curve obtained from active and passive source methods. In the this study, Surface waves data were collected using the measurements of MASW, ReMi and SPAC at the İzmir Bornova region. Dispersion curves obtained from surface wave methods were combined in wide frequency band and Vs-depth profiles were obtained using inversion. Reliability of the resulting soil profiles were provided by comparison with theoretical transfer function obtained from soil paremeters and observed soil transfer function from Nakamura technique and by examination of fitting between these functions. Vs values are changed between 200-830 m/s and engineering bedrock (Vs>760 m/s) depth is approximately 150 m.

  1. Northern Korean Peninsula 1-D velocity model from surface wave dispersion and full-waveform data

    Science.gov (United States)

    Lee, S. J.; Rhie, J.; Kim, S.; Kang, T. S.; Cho, C.

    2016-12-01

    Monitoring seismic activities in the northern Korean Peninsula is important not only for understanding the characteristics of earthquakes but also for watching nuclear tests. To better monitor those natural and man-made seismic activities, reliable seismic velocity models are required. However, the seismic velocity structure of the region is not known well due to the lack of available seismic data directly measured in the region. This study presents 1-D velocity models of the region using two different datasets comprised of two-year-long continuous waveform and the 2013 North Korea nuclear test event waveform recorded at stations surrounding the region. Two reference 1-D models for the inland and offshore areas (Western East Sea) were estimated by 1-D inversion of surface wave dispersion measurements from ambient noise cross-correlations of the continuous waveform. To investigate the variations in the velocity models, many 1-D models for the paths between the 2013 nuclear test site and stations in China and South Korea were constructed by forward waveform modeling. The velocity variations are not significant for both models representing the inland and offshore paths, respectively. The 1-D models for the inland paths are similar to the models constructed for the southern Korean Peninsula. Interestingly, waveforms sampling through the offshore paths are not well explained by simple 1-D isotropic models. The preliminary result indicates that there exists radial anisotropy with SH being faster than SV by 3-5% in the upper mantle beneath the offshore northern Korean Peninsula, although further studies are necessary to explain the origin of anisotropy. A proper characterization of propagation effects along the offshore paths would be useful for monitoring future nuclear tests because many seismic stations in the eastern South Korea record waveforms sampling the offshore region from the nuclear test site to those stations.

  2. VizieR Online Data Catalog: WOCS. LXVI. Radial velocity survey in M35 (Leiner+, 2015)

    Science.gov (United States)

    Leiner, E. M.; Mathieu, R. D.; Gosnell, N. M.; Geller, A. M.

    2015-09-01

    wavelength range, covering several prominent absorption lines including the MgB triplet. We present here all radial velocity measurements of the 1355 stars in our sample to date (see Table4), totaling ~8000 radial velocities (see Table3). M35 was observed in the X-ray by the XMM-Newton orbiting observatory for 8.6ks (02:37:10-05:00:50 UT) on 2008 September 20. The telescope boresight location was 6h8m54s, +24°20'00'' (J2000). The XMM field of view with r=15' does not extend as far from cluster center as the WOCS radial velocity survey (r=30', α=06h09m07.5s, δ=+24°20'28''). We cross-correlate the position of each X-ray source with the WOCS catalog to find potential optical counterparts to the X-ray sources (see Table9). (7 data files).

  3. The influence of surface on the running velocities of elite and amateur orienteer athletes.

    Science.gov (United States)

    Hébert-Losier, K; Jensen, K; Mourot, L; Holmberg, H-C

    2014-12-01

    We compared the reduction in running velocities from road to off-road terrain in eight elite and eight amateur male orienteer athletes to investigate whether this factor differentiates elite from amateur athletes. On two separate days, each subject ran three 2-km time trials and three 20-m sprints "all-out" on a road, on a path, and in a forest. On a third day, the running economy and maximal aerobic power of individuals were assessed on a treadmill. The elite orienteer ran faster than the amateur on all three surfaces and at both distances, in line with their better running economy and aerobic power. In the forest, the elites ran at a slightly higher percentage of their 2-km (∼3%) and 20-m (∼4%) road velocities. Although these differences did not exhibit traditional statistical significance, magnitude-based inferences suggested likely meaningful differences, particularly during 20-m sprinting. Of course, cognitive, mental, and physical attributes other than the ability to run on different surfaces are required for excellence in orienteering (e.g., a high aerobic power). However, we suggest that athlete-specific assessment of running performance on various surfaces and distances might assist in tailoring training and identifying individual strengths and/or weaknesses in an orienteer. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Sensitivities of surface wave velocities to the medium parameters in a radially anisotropic spherical Earth and inversion strategies

    Directory of Open Access Journals (Sweden)

    Sankar N. Bhattacharya

    2015-11-01

    Full Text Available Sensitivity kernels or partial derivatives of phase velocity (c and group velocity (U with respect to medium parameters are useful to interpret a given set of observed surface wave velocity data. In addition to phase velocities, group velocities are also being observed to find the radial anisotropy of the crust and mantle. However, sensitivities of group velocity for a radially anisotropic Earth have rarely been studied. Here we show sensitivities of group velocity along with those of phase velocity to the medium parameters VSV, VSH , VPV, VPH , h and density in a radially anisotropic spherical Earth. The peak sensitivities for U are generally twice of those for c; thus U is more efficient than c to explore anisotropic nature of the medium. Love waves mainly depends on VSH while Rayleigh waves is nearly independent of VSH . The sensitivities show that there are trade-offs among these parameters during inversion and there is a need to reduce the number of parameters to be evaluated independently. It is suggested to use a nonlinear inversion jointly for Rayleigh and Love waves; in such a nonlinear inversion best solutions are obtained among the model parameters within prescribed limits for each parameter. We first choose VSH, VSV and VPH within their corresponding limits; VPV and h can be evaluated from empirical relations among the parameters. The density has small effect on surface wave velocities and it can be considered from other studies or from empirical relation of density to average P-wave velocity.

  5. A systematic test of surface velocity radar (SVR) to improve flood discharge prediction

    Science.gov (United States)

    Zolezzi, G.; Zamler, D.; Laronne, J. B.; Salvaro, M.; Piazza, F.; Le Coz, J.; Welber, M.; Dramais, G.

    2011-12-01

    Measurement of streamflow at flood stage is normally prohibitive and is therefore not a standard task performed by hydrographic offices. Streamflow estimation at high stages is commonly achieved through transformation of gauged water levels to discharge through rating curves. These stage-discharge relationships often suffer from large errors especially above the highest gauged discharge values corresponding to morphologically formative conditions. Non-contact methods based on radar Doppler technology have recently emerged as promising options because they can remotely measure the surface water velocity without requiring contact of instruments with the stream. They have been used for more than a decade, notably in Japan, but they are expensive and are fixed with the radar beam directed to a small portion of the free surface width. The aim of our study is to test a portable, cheap, easy-to-apply radar-based technique (SVR: Surface Velocity Radar). We illustrate the outcomes of a systematic series of field campaigns performed in Israel, Italy and France with concomitant standard (mechanical and electromagnetic current meter) and modern (ADCP, LSPIV image analysis) techniques with cooperating regional authorities. The SVR has been deployed from bridges and/or channel banks on 5 different streams: the single-thread Adige and the braided Tagliamento rivers (NE Italy) the single-thread Arc-en-Maurienne River during reservoir flushing (French Alps) and the ephemeral, flashflood Wadi Eshtemoa and a small perennial stream at Ein-Fesh'ha springs (Israel). This has allowed to span a relatively broad range of discharge (1 to ~ 600 m3/s), flow velocity (0.5 to ~ 3.5 m/s) and ratio between bed roughness height to flow depth (~ 0.01 to ~ 0.5) while measuring both under steady and rapidly varying flow conditions. The key outcomes of the field campaigns are: (i) wherever a bridge is available and cross-sectional topography can be measured before and/or after a flood, comparable

  6. Retrieval of sea surface velocities using sequential Ocean Colour Monitor (OCM) data

    Digital Repository Service at National Institute of Oceanography (India)

    Prasad, J; Rajawat, A.S.; Pradhan, Y; Chauhan, O.S.; Nayak, S.R.

    =ISO-8859-1 Retrieval of sea surface velocities using sequential Ocean Colour Monitor (OCM) data J S Prasad1; , A S Rajawat1, Yaswant Pradhan1, O S Chauhan2 and S R Nayak1 Presently at Applied Geophysical Laboratories, Department of Geophysics... cross-correlation; co- registration. Proc. Indian Acad. Sci. (Earth Planet. Sci.), 111, No. 3, September 2002, pp. 189{195 ? Printed in India. 189 190 J S Prasad et al investigators (La Violette 1984; Vastano and Bor- ders 1984; Emery et al 1986; Kelly...

  7. Collisional Processing of Comet and Asteroid Surfaces: Velocity Effects on Absorption Spectra

    Science.gov (United States)

    Lederer, S. M.; Jensen, E. A.; Wooden, D. H.; Lindsay, S. S.; Smith, D. C.; Nakamura-Messenger, K.; Keller, L. P.; Cintala, M. J.; Zolensky, M. E.

    2012-01-01

    A new paradigm has emerged where 3.9 Gyr ago, a violent reshuffling reshaped the placement of small bodies in the solar system (the Nice model). Surface properties of these objects may have been affected by collisions caused by this event, and by collisions with other small bodies since their emplacement. These impacts affect the spectrographic observations of these bodies today. Shock effects (e.g., planar dislocations) manifest in minerals allowing astronomers to better understand geophysical impact processing that has occurred on small bodies. At the Experimental Impact Laboratory at NASA Johnson Space Center, we have impacted forsterite and enstatite across a range of velocities. We find that the amount of spectral variation, absorption wavelength, and full width half maximum of the absorbance peaks vary non-linearly with the velocity of the impact. We also find that the spectral variation increases with decreasing crystal size (single solid rock versus granular). Future analyses include quantification of the spectral changes with different impactor densities, temperature, and additional impact velocities. Results on diopside, fayalite, and magnesite can be found in Lederer et al., this meeting.

  8. Estimation of the p-wave velocity profile of elastic real data based on surface wave inversion

    NARCIS (Netherlands)

    Ponomarenko, A.V.; Kashtan, B.M.; Troyan, V.N.; Mulder, W.A.

    2013-01-01

    Recently, we proposed an analytical approach to invert for a smoothly varying near-surface P-wave velocity profile that has a squared slowness linearly decreasing with depth. The exact solution for such a velocity profile in the acoustic approximation can be expressed in terms of Airy functions and

  9. nowCOAST's Map Service for NOAA NWS NDFD Gridded Forecasts of Surface Wind Velocity Barb (knots) (Time Offsets)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Map Information: This nowCOAST time-offsets map service provides maps depicting the NWS surface wind velocity forecasts from the National Digital Forecast Database...

  10. Surface Wave Multipathing and its Influence on Phase Velocities Measured by Small Networks

    Science.gov (United States)

    Maupin, V.

    2011-12-01

    Networks of temporary broadband seismological stations are commonly deployed over dedicated targets. Measurement of surface wave phase velocity across the network and its depth-inversion gives us information about the structure below the network which is complementary to the information obtained from body-wave analysis. For small networks, we face however the fundamental problem that the dimensions of the heterogeneities to image are not large compared to the wavelengths of the surface waves used to image them. In addition, multipathing is very common is teleseismic surface waves at moderate frequencies and the complexity of the incoming wavefield has to be taken into account during the tomographic process. We perform a series of numerical simulations of surface wave propagation in 3-D structures using complex incoming wavefields in order to analyse how the nature of the incoming wavefield plays together with the 3-D structure to determine phases and amplitudes at the different stations of a network. We analyse how different tomographic methods cope with the complex wavefield, the consequences on the resolution of the resulting tomographic models and we try to provide recommendations for data selection. The numerical simulations are done using a multiple-scattering mode coupling scheme. The amount of multipathing is taken from a recent study using teleseismic surface waves recorded on a temporary network in Southern Norway. The period range of 20 to 200s and the 450km x 600km dimension of the network is also taken form the same study.

  11. Space Debris Surfaces (Computer Code): Probability of No Penetration Versus Impact Velocity and Obliquity

    Science.gov (United States)

    Elfer, N.; Meibaum, R.; Olsen, G.

    1995-01-01

    A unique collection of computer codes, Space Debris Surfaces (SD_SURF), have been developed to assist in the design and analysis of space debris protection systems. SD_SURF calculates and summarizes a vehicle's vulnerability to space debris as a function of impact velocity and obliquity. An SD_SURF analysis will show which velocities and obliquities are the most probable to cause a penetration. This determination can help the analyst select a shield design that is best suited to the predominant penetration mechanism. The analysis also suggests the most suitable parameters for development or verification testing. The SD_SURF programs offer the option of either FORTRAN programs or Microsoft-EXCEL spreadsheets and macros. The FORTRAN programs work with BUMPERII. The EXCEL spreadsheets and macros can be used independently or with selected output from the SD_SURF FORTRAN programs. Examples will be presented of the interaction between space vehicle geometry, the space debris environment, and the penetration and critical damage ballistic limit surfaces of the shield under consideration.

  12. Fast, large-scale, particle image velocimetry-based estimations of river surface velocity

    Science.gov (United States)

    Dobson, David W.; Todd Holland, K.; Calantoni, Joseph

    2014-09-01

    A modified high-speed implementation of cross-correlation (CC) based, large-scale particle image velocimetry (LSPIV) was used to estimate the surface velocity of a river with video collected from a gray-scale camera. To improve the quality of results in the high-noise low-signal environment, we introduce a temporal correlation averaging (TCA) scheme that merges a small number of correlation surfaces in the time domain. The TCA scheme is combined with a multi-size macroblock (MMB) sampling method that provides correlation scores from four different macroblock sizes. The TCA scheme is also used in conjunction with a signal-level indicator computed on the macroblock. The signal-level indicator is used to reject correlation scores prior to computation and helps to keep noisy results out of the TCA. These modifications were tested by comparing LSPIV calculations to Acoustic Doppler Current Profiler measurements. The percent difference of measured velocity between LSPIV with TCA and MMB and without TCA and MMB when compared to the ADCP was reduced by as much as 30%. The low processing cost of our modifications along with an efficient multithread implementation of LSPIV facilitates high speed processing of up to a few thousand vector points at rates that exceed the capture speed of common hardware.

  13. Motor unit action potential conduction velocity estimated from surface electromyographic signals using image processing techniques.

    Science.gov (United States)

    Soares, Fabiano Araujo; Carvalho, João Luiz Azevedo; Miosso, Cristiano Jacques; de Andrade, Marcelino Monteiro; da Rocha, Adson Ferreira

    2015-09-17

    In surface electromyography (surface EMG, or S-EMG), conduction velocity (CV) refers to the velocity at which the motor unit action potentials (MUAPs) propagate along the muscle fibers, during contractions. The CV is related to the type and diameter of the muscle fibers, ion concentration, pH, and firing rate of the motor units (MUs). The CV can be used in the evaluation of contractile properties of MUs, and of muscle fatigue. The most popular methods for CV estimation are those based on maximum likelihood estimation (MLE). This work proposes an algorithm for estimating CV from S-EMG signals, using digital image processing techniques. The proposed approach is demonstrated and evaluated, using both simulated and experimentally-acquired multichannel S-EMG signals. We show that the proposed algorithm is as precise and accurate as the MLE method in typical conditions of noise and CV. The proposed method is not susceptible to errors associated with MUAP propagation direction or inadequate initialization parameters, which are common with the MLE algorithm. Image processing -based approaches may be useful in S-EMG analysis to extract different physiological parameters from multichannel S-EMG signals. Other new methods based on image processing could also be developed to help solving other tasks in EMG analysis, such as estimation of the CV for individual MUs, localization and tracking of innervation zones, and study of MU recruitment strategies.

  14. Interannual variability of rock glacier surface velocities and its relationship to climatic conditions on a decadal scale: Some insights from the European Alps

    Science.gov (United States)

    Kellerer-Pirklbauer, Andreas; Bodin, Xavier; Delaloye, Reynald; Fischer, Andrea; Gärtner-Roer, Isabelle; Hartl, Lea; Kaufmann, Viktor; Krainer, Karl; Lambiel, Christophe; Mair, Volkmar; Marcer, Marco; Morra di Cella, Umberto; Scapozza, Cristian; Schoeneich, Philippe; Staub, Benno

    2017-04-01

    Active, inactive and relict rock glaciers are widespread periglacial landforms in the European Alps as revealed by several inventories elaborated for Slovenia, Austria, Switzerland, Italy, and France. Rock glaciers indicate present or past permafrost conditions in mountain environments and hence have a high climatic or paleoclimatic relevance. The monitoring of surface velocities at active rock glaciers has a long tradition in the European Alps with first terrestrial photogrammetric surveys in the Swiss and Austrian Alps already in the 1920s. Since the 1990s velocity monitoring activities have been substantially expanded but also institutionalized. Today, several research groups carry out annual or even continuous monitoring of rock glacier creep at more than 30 rock glaciers in Austria, France, Italy, and Switzerland. In many cases such a kinematic monitoring is jointly accomplished with meteorological and ground temperature monitoring in order to better understand the rock glacier-climate relationships and the reaction of rock glacier behavior to climatic changes. In this contribution we present a synthesis of the main results from long-term monitoring of several rock glaciers in the European Alps with at least annually-repeated data. Similarities but also differences of the movement patterns at the different sites are discussed, while the spatio-temporal pattern of the surface displacement is looked at against the climate context. In general, rock glacier surface velocities in the European Alps have been rather low during the 1980s and 1990s and reached a first peak in 2003/04 followed by a drastic drop until c.2007/08. Since then rock glacier surface velocities increased again with new velocity records in 2015/16 superior to the first peak around 2003/04. These creep rate maxima coincide with the warmest permafrost temperatures ever measured in boreholes and are likely a result of the continuously warm conditions at the ground surface over the past seven years.

  15. Toe clearance and velocity profiles of young and elderly during walking on sloped surfaces

    Directory of Open Access Journals (Sweden)

    Begg Rezaul K

    2010-04-01

    Full Text Available Abstract Background Most falls in older adults are reported during locomotion and tripping has been identified as a major cause of falls. Challenging environments (e.g., walking on slopes are potential interventions for maintaining balance and gait skills. The aims of this study were: 1 to investigate whether or not distributions of two important gait variables [minimum toe clearance (MTC and foot velocity at MTC (VelMTC] and locomotor control strategies are altered during walking on sloped surfaces, and 2 if altered, are they maintained at two groups (young and elderly female groups. Methods MTC and VelMTC data during walking on a treadmill at sloped surfaces (+3°, 0° and -3° were analysed for 9 young (Y and 8 elderly (E female subjects. Results MTC distributions were found to be positively skewed whereas VelMTC distributions were negatively skewed for both groups on all slopes. Median MTC values increased (Y = 33%, E = 7% at negative slope but decreased (Y = 25%, E = 15% while walking on the positive slope surface compared to their MTC values at the flat surface (0°. Analysis of VelMTC distributions also indicated significantly (p th percentile (Q1 values in the elderly at all slopes. Conclusion The young displayed a strong positive correlation between MTC median changes and IQR (interquartile range changes due to walking on both slopes; however, such correlation was weak in the older adults suggesting differences in control strategies being employed to minimize the risk of tripping.

  16. Horizontal velocities in the central and eastern United States from GPS surveys during the 1987-1996 interval

    Energy Technology Data Exchange (ETDEWEB)

    Snay, R.A.; Strange, W.E.

    1997-12-01

    The National Geodetic Survey and the Nuclear Regulatory Commission jointly organized GPS surveys in 1987, 1990, 1993, and 1996 to search for crustal deformation in the central and eastern United States (east of longitude 108{degrees}W). We have analyzed the data of these four surveys in combination with VLBI data observed during the 1979-1995 interval and GPS data for 22 additional surveys observed during the 1990-1996 interval. These latter GPS surveys served to establish accurately positioned geodetic marks in various states. Accordingly, we have computed horizontal velocities for 64 GPS sites and 12 VLBI sites relative to a reference frame for which the interior of the North American plate is considered fixed on average. None of our derived velocities exceeds 6 mm/yr in magnitude. Moreover, the derived velocity at each GPS site is statistically zero at the 95% confidence level except for the site BOLTON in central Ohio and the site BEARTOWN in southeastern Pennsylvania. However, as statistical theory would allow approximately 5% of the 64 GPS sites to fall our zero-velocity hypothesis, we are uncertain whether or not these estimated velocities for BOLTON and BEARTOWN reflect actual motion relative to the North American plate. We also computed horizontal strain rates for the cells formed by a 1{degrees} by 1{degrees} grid spanning the central and eastern United States. Corresponding shearing rates are everywhere less than 60 nanoradians/yr in magnitude, and no shearing rate differs statistically from zero at the 95% confidence level except for a grid cell near BEARTOWN whose rate is 57 {+-} 26 nanoradians/yr. Also corresponding areal dilatation rates are everywhere less than 40 nanostrain/yr in magnitude, and no dilatation rate differs statistically from zero at the 95% confidence level.

  17. Aero-servo-viscoelasticity theory: Lifting surfaces, plates, velocity transients, flutter, and instability

    Science.gov (United States)

    Merrett, Craig G.

    -partial differential equations. The spatial component of the governing equations is eliminated using a series expansion of basis functions and by applying Galerkin's method. The number of terms in the series expansion affects the convergence of the spatial component, and convergence is best determined by the von Koch rules that previously appeared for column buckling problems. After elimination of the spatial component, an ordinary integral-differential equation in time remains. The dynamic stability of elastic and viscoelastic problems is assessed using the determinant of the governing system of equations and the time component of the solution in the form exp (lambda t). The determinant is in terms of lambda where the values of lambda are the latent roots of the aero-servo-viscoelastic system. The real component of lambda dictates the stability of the system. If all the real components are negative, the system is stable. If at least one real component is zero and all others are negative, the system is neutrally stable. If one or more real components are positive, the system is unstable. In aero-servo-viscoelasticity, the neutrally stable condition is termed flutter. For an aero-servo-viscoelastic lifting surface, the unstable condition is historically termed torsional divergence. The more general aero-servo-viscoelastic theory has produced a number of important results, enumerated in the following list: 1. Subsonic panel flutter can occur before panel instability. This result overturned a long held assumption in aeroelasticity, and was produced by the novel application of the von Koch rules for convergence. Further, experimental results from the 1950s by the Air Force were retrieved to provide additional proof. 2. An expanded definition for flutter of a lifting surface. The legacy definition is that flutter is the first occurrence of simple harmonic motion of a structure, and the flight velocity at which this motion occurs is taken as the flutter speed. The expanded definition

  18. Adaptive computer-based spatial-filtering method for more accurate estimation of the surface velocity of debris flow.

    Science.gov (United States)

    Uddin, M S; Inaba, H; Itakura, Y; Yoshida, Y; Kasahara, M

    1999-11-10

    An adaptive computer-based spatial-filtering velocimeter to measure the surface velocity of a natural debris flow with high accuracy is described that can adjust the filter parameters, specifically, the slit width of the filter, based on the surface-pattern characteristics of the flow. A computer simulation confirms the effectiveness of this technique. The surface velocity of a natural debris flow at the Mt. Yakedake Volcano, Japan, was estimated by this adaptive method, and the results were compared with those obtained by two other methods: hardware-based spatial filtering and normal computer-based spatial filtering.

  19. Seismic velocity site characterization of 10 Arizona strong-motion recording stations by spectral analysis of surface wave dispersion

    Science.gov (United States)

    Kayen, Robert E.; Carkin, Brad A.; Corbett, Skye C.

    2017-10-19

    Vertical one-dimensional shear wave velocity (VS) profiles are presented for strong-motion sites in Arizona for a suite of stations surrounding the Palo Verde Nuclear Generating Station. The purpose of the study is to determine the detailed site velocity profile, the average velocity in the upper 30 meters of the profile (VS30), the average velocity for the entire profile (VSZ), and the National Earthquake Hazards Reduction Program (NEHRP) site classification. The VS profiles are estimated using a non-invasive continuous-sine-wave method for gathering the dispersion characteristics of surface waves. Shear wave velocity profiles were inverted from the averaged dispersion curves using three independent methods for comparison, and the root-mean-square combined coefficient of variation (COV) of the dispersion and inversion calculations are estimated for each site.

  20. Advective surface velocity in the north west Pacific derived from NOAA AVHRR images

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Akiyama, M.; Okada, Y.; Sugimori, Y.

    Using sequential AVHRR images in November 1983, nearsurface advective velocities are derived in the region Kuroshio south of Japan. For deriving the velocities two methods are used. One is the Method of Cross Correlation (MCC), using image pair...

  1. Workflow for near-surface velocity automatic estimation: Source-domain full-traveltime inversion followed by waveform inversion

    KAUST Repository

    Liu, Lu

    2017-08-17

    This paper presents a workflow for near-surface velocity automatic estimation using the early arrivals of seismic data. This workflow comprises two methods, source-domain full traveltime inversion (FTI) and early-arrival waveform inversion. Source-domain FTI is capable of automatically generating a background velocity that can kinematically match the reconstructed plane-wave sources of early arrivals with true plane-wave sources. This method does not require picking first arrivals for inversion, which is one of the most challenging aspects of ray-based first-arrival tomographic inversion. Moreover, compared with conventional Born-based methods, source-domain FTI can distinguish between slower or faster initial model errors via providing the correct sign of the model gradient. In addition, this method does not need estimation of the source wavelet, which is a requirement for receiver-domain wave-equation velocity inversion. The model derived from source-domain FTI is then used as input to early-arrival waveform inversion to obtain the short-wavelength velocity components. We have tested the workflow on synthetic and field seismic data sets. The results show source-domain FTI can generate reasonable background velocities for early-arrival waveform inversion even when subsurface velocity reversals are present and the workflow can produce a high-resolution near-surface velocity model.

  2. Public satisfaction survey of high friction surface treatment.

    Science.gov (United States)

    2017-04-01

    Missouri adults in Callaway County were surveyed to capture their satisfaction with a local high friction surface treatment on : westbound US 54. This treatment was implemented in Project J5P3012. The results are weighted proportionally to the county...

  3. Phase reconstruction from velocity-encoded MRI measurements – A survey of sparsity-promoting variational approaches

    KAUST Repository

    Benning, Martin

    2014-01-01

    In recent years there has been significant developments in the reconstruction of magnetic resonance velocity images from sub-sampled k-space data. While showing a strong improvement in reconstruction quality compared to classical approaches, the vast number of different methods, and the challenges in setting them up, often leaves the user with the difficult task of choosing the correct approach, or more importantly, not selecting a poor approach. In this paper, we survey variational approaches for the reconstruction of phase-encoded magnetic resonance velocity images from sub-sampled k-space data. We are particularly interested in regularisers that correctly treat both smooth and geometric features of the image. These features are common to velocity imaging, where the flow field will be smooth but interfaces between the fluid and surrounding material will be sharp, but are challenging to represent sparsely. As an example we demonstrate the variational approaches on velocity imaging of water flowing through a packed bed of solid particles. We evaluate Wavelet regularisation against Total Variation and the relatively recent second order Total Generalised Variation regularisation. We combine these regularisation schemes with a contrast enhancement approach called Bregman iteration. We verify for a variety of sampling patterns that Morozov\\'s discrepancy principle provides a good criterion for stopping the iterations. Therefore, given only the noise level, we present a robust guideline for setting up a variational reconstruction scheme for MR velocity imaging. © 2013 Elsevier Inc. All rights reserved.

  4. McDonald Observatory Planetary Search - A high precision stellar radial velocity survey for other planetary systems

    Science.gov (United States)

    Cochran, William D.; Hatzes, Artie P.

    1993-01-01

    The McDonald Observatory Planetary Search program surveyed a sample of 33 nearby F, G, and K stars since September 1987 to search for substellar companion objects. Measurements of stellar radial velocity variations to a precision of better than 10 m/s were performed as routine observations to detect Jovian planets in orbit around solar type stars. Results confirm the detection of a companion object to HD114762.

  5. Monitoring of surface velocity of hyper-concentrated flow in a laboratory flume by means of fully-digital PIV

    Science.gov (United States)

    Termini, Donatella; Di Leonardo, Alice

    2016-04-01

    High flow conditions, which are generally characterized by high sediment concentrations, do not permit the use of traditional measurement equipment. Traditional techniques usually are based on the intrusive measure of the vertical profile of flow velocity and on the linking of water depth with the discharge through the rating curve. The major disadvantage of these measurement techniques is that they are difficult to use and not safe for operators especially in high flow conditions. The point is that, as literature shows (see as an example Moramarco and Termini, 2015), especially in such conditions, the measurement of surface velocity distribution is important to evaluate the mean flow velocity and, thus, the flow discharge. In the last decade, image-based techniques have been increasingly used for surface velocity measurements (among others Joeau et al., 2008). Experimental program has been recently conducted at the Hydraulic laboratory of the Department of Civil, Environmental, Aerospatial and of Materials Engineering (DICAM) - University of Palermo (Italy) in order to analyze the propagation phenomenon of hyper-concentrated flow in a defense channel. The experimental apparatus includes a high-precision camera and a system allowing the images recording. This paper investigates the utility and the efficiency of the digital image-technique for remote monitoring of surface velocity in hyper-concentrated flow by the aid of data collected during experiments conducted in the laboratory flume. In particular the present paper attention is focused on the estimation procedure of the velocity vectors and on their sensitivity with parameters (number of images, spatial resolution of interrogation area,) of the images processing procedure. References Jodeau M., A. Hauet, A. Paquier, Le Coz J., Dramais G., Application and evaluation of LS-PIV technique for the monitoring of river surface in high flow conditions, Flow Measurements and Instrumentation, Vol.19, No.2, 2008, pp.117

  6. Mitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration

    KAUST Repository

    Sinha, Mrinal

    2015-08-19

    We propose an interferometric least-squares migration method that can significantly reduce migration artifacts due to statics and errors in the near-surface velocity model. We first choose a reference reflector whose topography is well known from the, e.g., well logs. Reflections from this reference layer are correlated with the traces associated with reflections from deeper interfaces to get crosscorrelograms. These crosscorrelograms are then migrated using interferometric least-squares migration (ILSM). In this way statics and velocity errors at the near surface are largely eliminated for the examples in our paper.

  7. Crustal surface wave velocity structure of the east Albany-Fraser Orogen, Western Australia, from ambient noise recordings

    Science.gov (United States)

    Sippl, C.; Kennett, B. L. N.; Tkalčić, H.; Gessner, K.; Spaggiari, C. V.

    2017-09-01

    Group and phase velocity maps in the period range 2-20 s for the Proterozoic east Albany-Fraser Orogen, Western Australia, are extracted from ambient seismic noise recorded with the 70-station ALFREX array. This 2 yr temporary installation provided detailed coverage across the orogen and the edge of the Neoarchean Yilgarn Craton, a region where no passive seismic studies of this scale have occurred to date. The surface wave velocities are rather high overall (>3 km s-1 nearly everywhere), as expected for exposed Proterozoic basement rocks. No clear signature of the transition between Yilgarn Craton and Albany-Fraser Orogen is observed, but several strong anomalies corresponding to more local geological features were obtained. A prominent, NE-elongated high-velocity anomaly in the northern part of the array is coincident with a Bouguer gravity high caused by the upper crustal metamorphic rocks of the Fraser Zone. This feature disappears towards longer periods, which hints at an exclusively upper crustal origin for this anomaly. Further east, the limestones of the Cenozoic Eucla Basin are clearly imaged as a pronounced low-velocity zone at short periods, but the prevalence of low velocities to periods of ≥5 s implies that the uppermost basement in this area is likewise slow. At longer periods, slightly above-average surface wave velocities are imaged below the Eucla Basin.

  8. Generalized additive regression models of discharge and mean velocity associated with direct-runoff conditions in Texas: Utility of the U.S. Geological Survey discharge measurement database

    Science.gov (United States)

    Asquith, William H.; Herrmann, George R.; Cleveland, Theodore G.

    2013-01-01

    A database containing more than 17,700 discharge values and ancillary hydraulic properties was assembled from summaries of discharge measurement records for 424 U.S. Geological Survey streamflow-gauging stations (stream gauges) in Texas. Each discharge exceeds the 90th-percentile daily mean streamflow as determined by period-of-record, stream-gauge-specific, flow-duration curves. Each discharge therefore is assumed to represent discharge measurement made during direct-runoff conditions. The hydraulic properties of each discharge measurement included concomitant cross-sectional flow area, water-surface top width, and reported mean velocity. Systematic and statewide investigation of these data in pursuit of regional models for the estimation of discharge and mean velocity has not been previously attempted. Generalized additive regression modeling is used to develop readily implemented procedures by end-users for estimation of discharge and mean velocity from select predictor variables at ungauged stream locations. The discharge model uses predictor variables of cross-sectional flow area, top width, stream location, mean annual precipitation, and a generalized terrain and climate index (OmegaEM) derived for a previous flood-frequency regionalization study. The mean velocity model uses predictor variables of discharge, top width, stream location, mean annual precipitation, and OmegaEM. The discharge model has an adjusted R-squared value of about 0.95 and a residual standard error (RSE) of about 0.22 base-10 logarithm (cubic meters per second); the mean velocity model has an adjusted R-squared value of about 0.67 and an RSE of about 0.063 fifth root (meters per second). Example applications and computations using both regression models are provided. - See more at: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE.1943-5584.0000635#sthash.jhGyPxgZ.dpuf

  9. Optical spectroscopy and velocity dispersions of galaxy clusters from the SPT-SZ survey

    Energy Technology Data Exchange (ETDEWEB)

    Ruel, J.; Bayliss, M. [Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States); Bazin, G.; Bocquet, S. [Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München (Germany); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Foley, R. J.; Stalder, B.; Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Aird, K. A. [University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Armstrong, R. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Bautz, M. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chapman, S. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Cho, H. M. [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States); Clocchiatti, A., E-mail: mbayliss@cfa.harvard.edu [Instituto de Astrofisica, Pontificia Universidad Catolica (Chile); and others

    2014-09-01

    We present optical spectroscopy of galaxies in clusters detected through the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). We report our own measurements of 61 spectroscopic cluster redshifts, and 48 velocity dispersions each calculated with more than 15 member galaxies. This catalog also includes 19 dispersions of SPT-observed clusters previously reported in the literature. The majority of the clusters in this paper are SPT-discovered; of these, most have been previously reported in other SPT cluster catalogs, and five are reported here as SPT discoveries for the first time. By performing a resampling analysis of galaxy velocities, we find that unbiased velocity dispersions can be obtained from a relatively small number of member galaxies (≲ 30), but with increased systematic scatter. We use this analysis to determine statistical confidence intervals that include the effect of membership selection. We fit scaling relations between the observed cluster velocity dispersions and mass estimates from SZ and X-ray observables. In both cases, the results are consistent with the scaling relation between velocity dispersion and mass expected from dark-matter simulations. We measure a ∼30% log-normal scatter in dispersion at fixed mass, and a ∼10% offset in the normalization of the dispersion-mass relation when compared to the expectation from simulations, which is within the expected level of systematic uncertainty.

  10. Estimation of Sway Velocity-Dependent Hydrodynamic Derivatives in Surface Ship Manoeuvring Using Ranse Based CFD

    Directory of Open Access Journals (Sweden)

    Sheeja Janardhanan

    2010-09-01

    Full Text Available The hydrodynamic derivatives appearing in the manoeuvring equations of motion are the primary parameters in the prediction of the trajectory of a vessel. Determination of these derivatives poses major challenge in ship manoeuvring related problems. This paper deals with one such problem in which an attempt has been made to numerically simulate the conventional straight line test in a towing tank using computational fluid dynamics (CFD. Free-surface effects have been neglected here. The domain size has been fixed as per ITTC guide lines. The grid size has been fixed after a thorough grid independency analysis and an optimum grid size has been chosen in order to ensure the insensitivity of the flow parameters to grid size and also to have reduced computational effort. The model has been oriented to wider range of drift angles to capture the non-linear effects and subsequently the forces and moments acting on the model in each angle have been estimated. The sway velocity dependent derivatives have been obtained through plots and curve-fits. The effect of finite water depth on the derivatives has also been looked into. The results have been compared with the available experimental and empirical values and the method was found to be promising.

  11. Seasonal and annual variations of mountain glaciers surface velocity, implications for ice dynamic. Case study: Karakorum and Pamir.

    Science.gov (United States)

    Nanni, Ugo; Scherler, Dirk; Ayoub, Francois; Malatesta, Luca; Herman, Frederic; Avouac, Jean-Philippe

    2017-04-01

    The Pamir and Karakorum regions are heavily glaciated and contain some of the largest and fastest mountain glaciers on Earth. Satellite imagery is key to constrain ice dynamics, in particular glacier surface velocities, and sub glacial processes, e.g., basal sliding or glacier erosion, in such large and remote regions. Significant velocity variations have previously been observed in this area and related to forcing by seasonal meltwater and surges mechanisms. However, the details of surges sequences, in particular their initiation and termination, and multiyear seasonal patterns are still poorly documented. Here we study 26 glaciers and quantify surface velocity variations at high temporal resolution from remote sensing. We present a processing strategy to exploit the large archives of optical satellite imagery available for the study area to obtain more than 500 velocity fields with a 16-day temporal resolution from April 2013 to July 2016. Glacier displacement is measured with a 1.5-meter resolution using sub-pixel correlation (COSI-Corr software) of Landsat-8 images. 14 out of the 26 studied glaciers show seasonal velocity variations with inter-annual variability. These glaciers typically accelerate in early spring, up to 150% of the winter velocity, starting in the ablation zone and occasionally propagating upstream. This behaviour supports a meteorological/hydrological forcing with higher velocities caused by an increase in water pressure due to melt water input during spring time. 12 out of the 26 glaciers underwent one sub-annual or multiyear surging event during the study period. The surging events do not follow a unique pattern. Velocity can increase by up 700% over a month, and with an acceleration that initiate anytime of the year. This suggests that surges are initiated by an internal process, e.g., shear heating or basal hydrology, rather than by an external seasonal forcing.

  12. Seismic Velocity Structure and Depth-Dependence of Anisotropy in the Red Sea and Arabian Shield from Surface Wave Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, S; Gaherty, J; Schwartz, S; Rodgers, A; Al-Amri, A

    2007-07-25

    We investigate the lithospheric and upper mantle structure as well as the depth-dependence of anisotropy along the Red Sea and beneath the Arabian Peninsula using receiver function constraints and phase velocities of surface waves traversing two transects of stations from the Saudi Arabian National Digital Seismic Network. Frequency-dependent phase delays of fundamental-mode Love and Rayleigh waves, measured using a cross-correlation procedure, require very slow shear velocities and the presence of anisotropy throughout the upper mantle. Linearized inversion of these data produce path-averaged 1D radially anisotropic models with about 4% anisotropy in the lithosphere, increasing to about 4.8% anisotropy across the lithosphere-asthenosphere boundary (LAB). Models with reasonable crustal velocities in which the mantle lithosphere is isotropic cannot satisfy the data. The lithospheric lid, which ranges in thickness from about 70 km near the Red Sea coast to about 90 km beneath the Arabian Shield, is underlain by a pronounced low-velocity zone with shear velocities as low as 4.1 km/s. Forward models, which are constructed from previously determined shear-wave splitting estimates, can reconcile surface and body wave observations of anisotropy. The low shear velocity values are similar to many other continental rift and oceanic ridge environments. These low velocities combined with the sharp velocity contrast across the LAB may indicate the presence of partial melt beneath Arabia. The anisotropic signature primarily reflects a combination of plate- and density-driven flow associated with active rifting processes in the Red Sea.

  13. Spectroscopic survey of the Galaxy with Gaia : I. Design and performance of the Radial Velocity Spectrometer

    NARCIS (Netherlands)

    Katz, D; Munari, U; Cropper, M; Zwitter, T; Thevenin, F; David, M; Viala, Y; Crifo, F; Gomboc, A; Royer, F; Arenou, F; Marrese, P; Sordo, R; Wilkinson, Mark; Vallenari, A; Turon, C; Helmi, A; Bono, G; Perryman, M; Gomez, A; Tomasella, L; Boschi, F; Morin, D; Haywood, M; Soubiran, C; Castelli, F; Bijaoui, A; Bertelli, G; Prsa, A; Mignot, S; Sellier, A; Baylac, MO; Lebreton, Y; Jauregi, U; Siviero, A; Bingham, R; Chemla, F; Coker, J; Dibbens, T; Hancock, B; Holland, A; Horville, D; Huet, JM; Laporte, P; Melse, T; Sayede, F; Stevenson, TJ; Vola, P; Walton, D; Winter, B

    2004-01-01

    The definition and optimization studies for the Gaia satellite spectrograph, the 'radial velocity spectrometer' (RVS), converged in late 2002 with the adoption of the instrument baseline. This paper reviews the characteristics of the selected configuration and presents its expected performance. The

  14. Slope-Velocity-Equilibrium and evolution of surface roughness on a stony hillslope

    Science.gov (United States)

    Slope-velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and bed morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow ...

  15. A mechanical diagnosis of the ice flow around Dome C: Elmer/Ice 3D simulations constrained by measured surface velocities and radar isochrones.

    Science.gov (United States)

    Passalacqua, Olivier; Cavitte, Marie; Frezzotti, Massimo; Gagliardini, Olivier; Gillet-Chaulet, Fabien; Parrenin, Frédéric; Ritz, Catherine; Vittuari, Luca; Young, Duncan

    2017-04-01

    The Dome C region has been densely surveyed and studied for the last decades, in particular to describe the shape of the ice surface, the bedrock relief, the surface velocity, the age and fabric structure of the ice, and its vertical temperature profile. No comprehensive ice flow modelling constrained by all of these field data has been done so far in this region. In particular, the Dome C has recently been targetted as an oldest-ice area, so that we intend to take advantage of a 2016 airborne radar survey that revealed the deep radar isochrones south-west of Dome C, and provides unprecendented constraints for the ice flow description. The Stokes equations are solved with the Elmer/Ice finite element solver, on a 80x110 km2 3D domain, for three different values of the Glen exponent n (1, 3 and 4.5), and for different fabric profiles. The goal of this study is threefold. First, as the range of stress types (longitudinal, transverse, and vertical compression-only) are well covered around Dome C, the observed surface velocities should efficiently constrain the possible values of the rheological parameters (Glen exponent and fluidity), and the basal sliding. Then, we apply an anisotropic flow law to correctly model the age structure, observed on the top 4/5th of the ice thickness, so that we induce mechanically-correct ages for the basal layers. Finally, once the ice mechanics is obtained, we compare the modelled vertical velocity profiles with 1D synthetic profiles, to assess the validity conditions of 1D modelling approaches, which are much more flexible tools for ensemble simulations or inversions.

  16. OCT-based quantification of flow velocity, shear force, and power generated by a biological ciliated surface (Conference Presentation)

    Science.gov (United States)

    Huang, Brendan K.; Khokha, Mustafa K.; Loewenberg, Michael; Choma, Michael A.

    2016-03-01

    In cilia-driven fluid flow physiology, quantification of flow velocity, shearing force, and power dissipation is important in defining abnormal ciliary function. The capacity to generate flow can be robustly described in terms of shearing force. Dissipated power can be related to net ATP consumption by ciliary molecular motors. To date, however, only flow velocity can be routinely quantified in a non-invasive, non-contact manner. Additionally, traditional power-based metrics rely on metabolic consumption that reflects energy consumption not just from cilia but also from all active cellular processes. Here, we demonstrate the estimation of all three of these quantities (flow velocity, shear force, and power dissipation) using only optical coherence tomography (OCT). Specifically, we develop a framework that can extract force and power information from vectorial flow velocity fields obtained using OCT-based methods. We do so by (a) estimating the viscous stress tensor from flow velocity fields to estimate shearing force and (b) using the viscous stress tensor to estimate the power dissipation function to infer total mechanical power. These estimates have the advantage of (a) requiring only a single modality, (b) being non-invasive in nature, and (c) being reflective of only the net power work generated by a ciliated surface. We demonstrate our all-optical approach to the estimation of these parameters in the Xenopus animal model system under normal and increased viscous loading. Our preliminary data support the hypothesis that the Xenopus ciliated surface can increase force output under loading conditions.

  17. Effects of Water Velocity and Specific Surface Area on Filamentous Periphyton Biomass in an Artificial Stream Mesocosm

    Directory of Open Access Journals (Sweden)

    Jin Chul Joo

    2013-10-01

    Full Text Available To evaluate the effects of water velocity and artificial substratum characteristics on the growth rate and biomass accumulation of periphyton, an artificial stream mesocosm experiment was conducted using alternative water sources collected from the Mangwall Stream (MW, the Han River (HR, and bank filtration water (BFW from the Han River in the Republic of Korea. The measured concentrations of organic matter and inorganic nutrients in the MW were higher than in the HR and BFW. The surface of tile is relatively smooth and nonporous, whereas the surfaces of concrete and pebble are rough with numerous isolated pores in which filamentous periphyton become immobilized against hydrodynamic shear stress and mat tensile strength. Compared with the periphyton biomass of the HR and BFW, the peak biomass in the MW was significantly higher due to higher nutrient concentrations in the MW. Reasonable linear relationships (R2 ≥ 0.69 between water velocity and total periphyton biomass/growth rate were obtained, indicating that water velocities above critical values can cause a reduction in biomass accrual. In addition, reasonable relationships (R2 ≥ 0.58 between specific surface area and total periphyton biomass were obtained for the HR and BFW, indicating that an increase in the specific surface area of the substratum can lead to an increase in periphyton biomass in a nutrient-poor water body. Principal components analysis (PCA results indicate that nutrient concentrations were the first dominant limiting factor for the growth and accumulation of periphyton, and water velocity and the specific surface area of the substratum were determined to be potential limiting factors. Consequently, the growth rate and biomass accumulation of periphyton were considered to be a complex function of nutrient concentrations, water velocities, and substratum characteristics.

  18. Crustal velocity structure of the Deccan Volcanic Province, Indian Peninsula, from observed surface wave dispersion

    Directory of Open Access Journals (Sweden)

    Gaddale Suresh

    2014-08-01

    Full Text Available Through inversion of fundamental mode group velocities of Love and Rayleigh waves, we study the crustal and subcrustal structure across the central Deccan Volcanic Province (DVP, which is one of the world’s largest terrestrial flood basalts. Our analysis is based on broadband seismograms recorded at seismological station Bhopal (BHPL in the central India from earthquakes located near west coast of India, with an average epicentral distance about 768 km. The recording station and epicentral zone are situated respectively on the northern and southern edges of DVP with wave paths across central DVP. The period of group velocity data ranges from 5 to 60 s for Rayleigh waves and 5 to 45 s for Love waves. Using the genetic algorithm, the observed data have been inverted to obtain the crust and subcrustal velocity structure along the wavepaths. Using this procedure, a similar velocity structure was also obtained earlier for the northwestern DVP, which is in the west of the present study region. Comparison of results show that the crustal thickness decreases westward from central DVP (39.6 km to northwestern DVP (37.8 km along with the decrease of thickness of upper crust; while the thickness of lower crust remains nearly same. From east to west S-wave velocity in the upper crust decreases by 2 to 3 per cent, while P-wave velocity in the whole crust and subcrust decreases by 3 to 6 per cent. The P- and S-wave velocities are positively correlated with crustal thickness and negatively correlated with earth’s heat flow. It appears that the elevated crustal and subcrustal temperature in the western side is the main factor for low velocities on this side.

  19. HF Radar Bistatic Measurement of Surface Current Velocities: Drifter Comparisons and Radar Consistency Checks

    OpenAIRE

    Lipa, Belinda; Whelan, Chad; Rector, Bill; Nyden, Bruce

    2009-01-01

    We describe the operation of a bistatic HF radar network and outline analysis methods for the derivation of the elliptical velocity components from the radar echo spectra. Bistatic operation is illustrated by application to a bistatic pair: Both remote systems receive backscattered echo, with one remote system in addition receiving bistatic echoes transmitted by the other. The pair produces elliptical velocity components in addition to two sets of radials. Results are compared with drifter me...

  20. Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - JPEG Images of Sound Velocity Profiles

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Bear Lake is a tectonic lake that has existed for at least several hundred thousand years. The lake basin is a relatively simple half graben, a spoon-shaped...

  1. 02031 - Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - Sound Velocity Profiles (SVP)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Bear Lake is a tectonic lake that has existed for at least several hundred thousand years. The lake basin is a relatively simple half graben, a spoon-shaped...

  2. CO desorption from a catalytic surface: elucidation of the role of steps by velocity-selected residence time measurements.

    Science.gov (United States)

    Golibrzuch, Kai; Shirhatti, Pranav R; Geweke, Jan; Werdecker, Jörn; Kandratsenka, Alexander; Auerbach, Daniel J; Wodtke, Alec M; Bartels, Christof

    2015-02-04

    Directly measuring the rate of a surface chemical reaction remains a challenging problem. For example, even after more than 30 years of study, there is still no agreement on the kinetic parameters for one of the simplest surface reactions: desorption of CO from Pt(111). We present a new experimental technique for determining rates of surface reactions, the velocity-selected residence time method, and demonstrate it for thermal desorption of CO from Pt(111). We use UV−UV double resonance spectroscopy to record surface residence times at selected final velocities of the desorbing CO subsequent to dosing with a pulsed molecular beam. Velocity selection differentiates trapping-desorption from direct scattering and removes influences on the temporal profile arising from the velocity distribution of the desorbing CO. The kinetic data thus obtained are of such high quality that bi-exponential desorption kinetics of CO from Pt(111) can be clearly seen. We assign the faster of the two rate processes to desorption from (111) terraces, and the slower rate process to sequential diffusion from steps to terraces followed by desorption. The influence of steps, whose density may vary from crystal to crystal, accounts for the diversity of previously reported (single exponential) kinetics results. Using transition-state theory, we derive the binding energy of CO to Pt(111) terraces, D(0)(terr) (Pt−CO) = 34 ± 1 kcal/mol (1.47 ± 0.04 eV) for the low coverage limit (≤0.03 ML) where adsorbate−adsorbate interactions are negligible. This provides a useful benchmark for electronic structure theory of adsorbates on metal surfaces.

  3. Magnetic and velocity fluctuations from nonlinearly coupled tearing modes in the reversed field pinch with and without the reversal surface

    Science.gov (United States)

    Craig, D.; Martin, D.; Den Hartog, D. J.; Nornberg, M. D.; Reusch, J. A.

    2017-08-01

    We investigate the role of poloidal mode number m = 0 fluctuations on m = 1 velocity and magnetic field fluctuations in the Reversed Field Pinch (RFP). Removing the m = 0 resonant surface in the Madison Symmetric Torus (MST), results in suppressed m = 0 activity without a reduction in m = 1 magnetic activity. However, the m = 1 velocity fluctuations and fluctuation-induced mean emf are reduced as m = 0 modes are suppressed. Velocity fluctuations are measured directly using fast Doppler spectroscopy. Similar results are seen in visco-resistive MHD simulation with the DEBS code. An artificial line-averaged velocity diagnostic is developed for DEBS simulations to facilitate direct comparisons with experimental measurements. The sensitivity of the m = 1 velocity fluctuations and corresponding emf to changes in m = 0 mode activity is a feature of tearing modes in the nonlinear regime with a spectrum of interacting modes. These results have implications for RFP sustainment strategies and inform our understanding of the role of magnetic turbulence in astrophysical contexts.

  4. A compendium of P- and S-wave velocities from surface-to-borehole logging; summary and reanalysis of previously published data and analysis of unpublished data

    Science.gov (United States)

    Boore, David M.

    2003-01-01

    For over 28 years, the U.S. Geological Survey (USGS) has been acquiring seismic velocity and geologic data at a number of locations in California, many of which were chosen because strong ground motions from earthquakes were recorded at the sites. The method for all measurements involves picking first arrivals of P- and S-waves from a surface source recorded at various depths in a borehole (as opposed to noninvasive methods, such as the SASW method [e.g., Brown et al., 2002]). The results from most of the sites are contained in a series of U.S. Geological Survey Open-File Reports (see References). Until now, none of the results have been available as computer files, and before 1992 the interpretation of the arrival times was in terms of piecemeal interval velocities, with no attempt to derive a layered model that would fit the travel times in an overall sense (the one exception is Porcella, 1984). In this report I reanalyze all of the arrival times in terms of layered models for P- and for S-wave velocities at each site, and I provide the results as computer files. In addition to the measurements reported in the open-file reports, I also include some borehole results from other reports, as well as some results never before published. I include data for 277 boreholes (at the time of this writing; more will be added to the web site as they are obtained), all in California (I have data from boreholes in Washington and Utah, but these will be published separately). I am also in the process of interpreting travel time data obtained using a seismic cone penetrometer at hundreds of sites; these data can be interpreted in the same way of those obtained from surface-to-borehole logging. When available, the data will be added to the web site (see below for information on obtaining data from the World Wide Web (WWW)). In addition to the basic borehole data and results, I provide information concerning strong-motion stations that I judge to be close enough to the boreholes

  5. A Mobile System for Measuring Water Surface Velocities Using Unmanned Aerial Vehicle and Large-Scale Particle Image Velocimetry

    Science.gov (United States)

    Chen, Y. L.

    2015-12-01

    Measurement technologies for velocity of river flow are divided into intrusive and nonintrusive methods. Intrusive method requires infield operations. The measuring process of intrusive methods are time consuming, and likely to cause damages of operator and instrument. Nonintrusive methods require fewer operators and can reduce instrument damages from directly attaching to the flow. Nonintrusive measurements may use radar or image velocimetry to measure the velocities at the surface of water flow. The image velocimetry, such as large scale particle image velocimetry (LSPIV) accesses not only the point velocity but the flow velocities in an area simultaneously. Flow properties of an area hold the promise of providing spatially information of flow fields. This study attempts to construct a mobile system UAV-LSPIV by using an unmanned aerial vehicle (UAV) with LSPIV to measure flows in fields. The mobile system consists of a six-rotor UAV helicopter, a Sony nex5T camera, a gimbal, an image transfer device, a ground station and a remote control device. The activate gimbal helps maintain the camera lens orthogonal to the water surface and reduce the extent of images being distorted. The image transfer device can monitor the captured image instantly. The operator controls the UAV by remote control device through ground station and can achieve the flying data such as flying height and GPS coordinate of UAV. The mobile system was then applied to field experiments. The deviation of velocities measured by UAV-LSPIV of field experiments and handhold Acoustic Doppler Velocimeter (ADV) is under 8%. The results of the field experiments suggests that the application of UAV-LSPIV can be effectively applied to surface flow studies.

  6. 3-D Seismic Velocity Structure of the Hawaii Hotspot from Joint Inversion of Body Wave and Surface Wave data

    Science.gov (United States)

    Cheng, C.; Allen, R. M.; Porritt, R. W.

    2012-12-01

    The Hawaii hotspot and the associated chain of islands have been long regarded as the case example of a deep-rooted mantle plume. However the efforts to detect a thermal plume seismically have been inconclusive. In this study we combine the complementary sensitivities of body- and surface-waves in order to improve resolution of mantle structure beneath Hawaii. Adding surface-wave constraints to the body wave inversion improves the resolution of the crustal and upper mantle structure. We used data from the deployment of temporary broadband ocean-bottom seismometers (OBS) of the Hawaiian Plume-Lithosphere Undersea Melt Experiment (PLUME) together with data from the on-shore stations in order to make the most complete dataset available. In a first step, we obtained stable and reliable OBS orientations over a range of earthquake back-azimuths using teleseismic P-wave particle motions. Due to the high noise of the OBS data in some frequency bands, we began by filtering in the period band of 0.04-1Hz. Using the proper channel orientations, we measured ~800 S-wave relative arrival times (direct S and SKS phases) on the SV component using muti-channel cross correlation. We applied the two-plane wave tomography method to generate surface wave phase velocity information. We use surface waves from 71 events with magnitude greater than 5.8 to generate phase velocity maps from 25 sec to 100 sec. These maps clearly show the low velocities beneath the islands surrounded by relatively high phase velocity. The pure S wave inversion result shows the 3-D structure beneath the PLUME array to a depth of 1000km and reveals a several-hundred-kilometer-wide region of low velocities beneath Hawaii that dips to the southeast. The low velocities continue downward through the mantle transition zone and extend into the uppermost lower-mantle where our resolution begins to degrade. These images are consistent with the interpretation that the Hawaiian hotspot is the result of an upwelling high

  7. Noncontact methods for measuring water-surface elevations and velocities in rivers: Implications for depth and discharge extraction

    Science.gov (United States)

    Nelson, Jonathan M.; Kinzel, Paul J.; McDonald, Richard R.; Schmeeckle, Mark

    2016-01-01

    Recently developed optical and videographic methods for measuring water-surface properties in a noninvasive manner hold great promise for extracting river hydraulic and bathymetric information. This paper describes such a technique, concentrating on the method of infrared videog- raphy for measuring surface velocities and both acoustic (laboratory-based) and laser-scanning (field-based) techniques for measuring water-surface elevations. In ideal laboratory situations with simple flows, appropriate spatial and temporal averaging results in accurate water-surface elevations and water-surface velocities. In test cases, this accuracy is sufficient to allow direct inversion of the governing equations of motion to produce estimates of depth and discharge. Unlike other optical techniques for determining local depth that rely on transmissivity of the water column (bathymetric lidar, multi/hyperspectral correlation), this method uses only water-surface information, so even deep and/or turbid flows can be investigated. However, significant errors arise in areas of nonhydrostatic spatial accelerations, such as those associated with flow over bedforms or other relatively steep obstacles. Using laboratory measurements for test cases, the cause of these errors is examined and both a simple semi-empirical method and computational results are presented that can potentially reduce bathymetric inversion errors.

  8. Seismic Technology Adapted to Analyzing and Developing Geothermal Systems Below Surface-Exposed High-Velocity Rocks Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Hardage, Bob A. [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; DeAngelo, Michael V. [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Ermolaeva, Elena [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Hardage, Bob A. [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Remington, Randy [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Sava, Diana [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Wagner, Donald [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology; Wei, Shuijion [Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology

    2013-02-01

    The objective of our research was to develop and demonstrate seismic data-acquisition and data-processing technologies that allow geothermal prospects below high-velocity rock outcrops to be evaluated. To do this, we acquired a 3-component seismic test line across an area of exposed high-velocity rocks in Brewster County, Texas, where there is high heat flow and surface conditions mimic those found at numerous geothermal prospects. Seismic contractors have not succeeded in creating good-quality seismic data in this area for companies who have acquired data for oil and gas exploitation purposes. Our test profile traversed an area where high-velocity rocks and low-velocity sediment were exposed on the surface in alternating patterns that repeated along the test line. We verified that these surface conditions cause non-ending reverberations of Love waves, Rayleigh waves, and shallow critical refractions to travel across the earth surface between the boundaries of the fast-velocity and slow-velocity material exposed on the surface. These reverberating surface waves form the high level of noise in this area that does not allow reflections from deep interfaces to be seen and utilized. Our data-acquisition method of deploying a box array of closely spaced geophones allowed us to recognize and evaluate these surface-wave noise modes regardless of the azimuth direction to the surface anomaly that backscattered the waves and caused them to return to the test-line profile. With this knowledge of the surface-wave noise, we were able to process these test-line data to create P-P and SH-SH images that were superior to those produced by a skilled seismic data-processing contractor. Compared to the P-P data acquired along the test line, the SH-SH data provided a better detection of faults and could be used to trace these faults upward to the boundaries of exposed surface rocks. We expanded our comparison of the relative value of S-wave and P-wave seismic data for geothermal

  9. Application and evaluation of LS-PIV technique for the monitoring of river surface velocities in high flow conditions

    OpenAIRE

    Jodeau, M.; Hauet, A.; Paquier, A.; Le Coz, J.; Dramais, G.

    2008-01-01

    Large Scale Particle Image Velocimetry (LS-PIV) is used to measure the surface flow velocities in a mountain stream during high flow conditions due to a reservoir release. A complete installation including video acquisition from a mobile elevated viewpoint and artificial flow seeding has been developed and implemented. The LS-PIV method was adapted in order to take into account the specific constraints of these high flow conditions. Using a usual LS-PIV data processing, significant variations...

  10. The Radial Velocity Experiment (RAVE) : Second data release

    NARCIS (Netherlands)

    Zwitter, T.; Siebert, A.; Munari, U.; Freeman, K. C.; Siviero, A.; Watson, F. G.; Fulbright, J. P.; Wyse, R. F. G.; Campbell, R.; Seabroke, G. M.; Williams, M.; Steinmetz, M.; Bienayme, O.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Navarro, J. F.; Anguiano, B.; Boeche, C.; Burton, D.; Cass, P.; Dawe, J.; Fiegert, K.; Hartley, M.; Russell, K.; Veltz, L.; Bailin, J.; Binney, J.; Bland-Hawthorn, J.; Brown, A.; Dehnen, W.; Evans, N. W.; Fiorentin, P. Re; Fiorucci, M.; Gerhard, O.; Gibson, B.; Kelz, A.; Kuijken, K.; Matijevic, G.; Minchev, I.; Parker, Q. A.; Penarrubia, J.; Quillen, A.; Read, M. A.; Reid, W.; Roeser, S.; Ruchti, G.; Scholz, R. -D.; Smith, M. C.; Sordo, R.; Tolstoi, E.; Tomasella, L.; Vidrih, S.; De Boer, E. Wylie

    We present the second data release of the Radial Velocity Experiment ( RAVE), an ambitious spectroscopic survey to measure radial velocities and stellar atmosphere parameters ( temperature, metallicity, surface gravity, and rotational velocity) of up to one million stars using the 6 dF multi-object

  11. Validated 3D Velocity Models in Asia from Joint Regional Body- and Surface-Wave Tomography

    Science.gov (United States)

    2009-02-17

    sedimentary basin structures across the region (e.g. Tarim , Ordos) persisting into the uppermost mantle. We show additional slices of the JWM model at 30...sedimentary basins or anomalous mantle structures, the assumed relationship may be wrong, leading to errors in the velocity model derived from the

  12. Nonexponential decay of velocity correlations in surface diffusion: The role of interactions and ordering

    DEFF Research Database (Denmark)

    Vattulainen, Ilpo Tapio; Hjelt, T.; Ala-Nissila, T.

    2000-01-01

    We study the diffusive dynamics of adparticles in two model systems with strong interactions by considering the decay of the single-particle velocity correlation function phi (t). In accordance with previous studies, we find phi (t) to decay nonexponentially and follow a power-law phi (t)similar ...

  13. Effect of slip velocity on oscillatory MHD flow of stretched surface ...

    African Journals Online (AJOL)

    Analytical solution of an oscillatory boundary layer flow bounded by two horizontal flat plates, one of which is oscillating in its own plane and the other at rest, is developed by asymptotic expansion in order of epsilon for velocity, temperature and magnetic fields. The fluid and the plates are in a state of solid body rotation with ...

  14. The impact of Surface Wind Velocity Data Assimilation on the Predictability of Plume Advection in the Lower Troposphere

    Science.gov (United States)

    Sekiyama, Thomas; Kajino, Mizuo; Kunii, Masaru

    2017-04-01

    The authors investigated the impact of surface wind velocity data assimilation on the predictability of plume advection in the lower troposphere exploiting the radioactive cesium emitted by the Fukushima nuclear accident in March 2011 as an atmospheric tracer. It was because the radioactive cesium plume was dispersed from the sole point source exactly placed at the Fukushima Daiichi Nuclear Power Plant and its surface concentration was measured at many locations with a high frequency and high accuracy. We used a non-hydrostatic regional weather prediction model with a horizontal resolution of 3 km, which was coupled with an ensemble Kalman filter data assimilation system in this study, to simulate the wind velocity and plume advection. The main module of this weather prediction model has been developed and used operationally by the Japan Meteorological Agency (JMA) since before March 2011. The weather observation data assimilated into the model simulation were provided from two data resources; [#1] the JMA observation archives collected for numerical weather predictions (NWPs) and [#2] the land-surface wind velocity data archived by the JMA surface weather observation network. The former dataset [#1] does not contain land-surface wind velocity observations because their spatial representativeness is relatively small and therefore the land-surface wind velocity data assimilation normally deteriorates the more than one day NWP performance. The latter dataset [#2] is usually used for real-time weather monitoring and never used for the data assimilation of more than one day NWPs. We conducted two experiments (STD and TEST) to reproduce the radioactive cesium plume behavior for 48 hours from 12UTC 14 March to 12UTC 16 March 2011 over the land area of western Japan. The STD experiment was performed to replicate the operational NWP using only the #1 dataset, not assimilating land-surface wind observations. In contrast, the TEST experiment was performed assimilating both

  15. Calculation of the Arc Velocity Along the Polluted Surface of Short Glass Plates Considering the Air Effect

    Directory of Open Access Journals (Sweden)

    Tao Yuan

    2012-03-01

    Full Text Available To investigate the microphysics mechanism and the factors that influence arc development along a polluted surface, the arc was considered as a plasma fluid. Based on the image method and the collision ionization theory, the electric field of the arc needed to maintain movement with different degrees of pollution was calculated. According to the force of the charged particle in an arc plasma stressed under an electric field, a calculation model of arc velocity, which is dependent on the electric field of the arc head that incorporated the effects of airflow around the electrode and air resistance is presented. An experiment was carried out to measure the arc velocity, which was then compared with the calculated value. The results of the experiment indicated that the lighter the pollution is, the larger the electric field of the arc head and arc velocity is; when the pollution is heavy, the effect of thermal buoyancy that hinders arc movement increases, which greatly reduces the arc velocity.

  16. Surface gravity analysis of the NIRSPEC Brown Dwarf Spectroscopic Survey

    Science.gov (United States)

    Martin, Emily; McLean, Ian S.; Mace, Gregory N.; Logsdon, Sarah E.; Rice, Emily L.

    2015-01-01

    We present an analysis of J band spectra for over two hundred M, L, and T dwarfs obtained from the Brown Dwarf Spectroscopic Survey (BDSS) using NIRSPEC on the Keck II Telescope. This R~2000 sample includes spectra presented in McLean et al. (2003), as well as many new, unpublished spectra observed for the BDSS, more than doubling the size of the original survey. We determine surface gravity-sensitive spectral indices from the literature, which probe K I and FeH absorption, and we estimate uncertainties using a Monte Carlo iterative method. With these indices we characterize surface gravities of our targets in order to disentangle temperature and age of brown dwarfs and low mass stars of various masses.

  17. Vectorial velocity filter for ultracold neutrons based on a surface-disordered mirror system

    Science.gov (United States)

    Chizhova, L. A.; Rotter, S.; Jenke, T.; Cronenberg, G.; Geltenbort, P.; Wautischer, G.; Filter, H.; Abele, H.; Burgdörfer, J.

    2014-03-01

    We perform classical three-dimensional Monte Carlo simulations of ultracold neutrons scattering through an absorbing-reflecting mirror system in the Earth's gravitational field. We show that the underlying mixed phase space of regular skipping motion and random motion due to disorder scattering can be exploited to realize a vectorial velocity filter for ultracold neutrons. The absorbing-reflecting mirror system proposed allows beams of ultracold neutrons with low angular divergence to be formed. The range of velocity components can be controlled by adjusting the geometric parameters of the system. First experimental tests of its performance are presented. One potential future application is the investigation of transport and scattering dynamics in confined systems downstream of the filter.

  18. Investigating Near Surface S-Wave Velocity Properties Using Ambient Noise in Southwestern Taiwan

    Directory of Open Access Journals (Sweden)

    Chun-Hsiang Kuo

    2015-01-01

    Full Text Available Ambient noise is typically used to estimate seismic site effects and velocity profiles instead of earthquake recordings, especially in areas with limited seismic data. The dominant Horizontal to Vertical Spectral Ratio (HVSR frequency of ambient noise is correlated to Vs30, which is the average S-wave velocity in the top 30 m. Vs30 is a widely used parameter for defining seismic amplification in earthquake engineering. HVSR can detect the vertical discontinuity of velocities, that is, the interfaces between hard bedrock and soft sediments. In southwestern Taiwan most strong motion stations are located in the plains and show a dominant frequency lower than 3 Hz. Several stations near the coast have low dominant frequencies of less than 1 Hz. The dominant frequencies are higher than 4 Hz at piedmont stations. The stations in the mountains with dominant frequencies over 8 Hz are typically located on very hard sites. This study analyzed the HVSR characteristics under different seismic site conditions considering the Vs30 from previous study (Kuo et al. 2012. The result implies that HVSRs are a better tool than Vs30 to classify the sites where bedrock is deeper than 30 m. Furthermore, we found a linear correlation between Vs30 and dominant HVSR frequency which could be used as a proxy of Vs30. The Vs30 map in this area was derived using the Engineering Geological Database for Taiwan Strong Motion Instrumentation Program (EGDT. The comparable distribution pattern between the dominant frequency and Vs30 demonstrate that HVSR can recognize S-wave velocity properties at the shallow subsurface.

  19. DeepVel: Deep learning for the estimation of horizontal velocities at the solar surface

    Science.gov (United States)

    Asensio Ramos, A.; Requerey, I. S.; Vitas, N.

    2017-07-01

    Many phenomena taking place in the solar photosphere are controlled by plasma motions. Although the line-of-sight component of the velocity can be estimated using the Doppler effect, we do not have direct spectroscopic access to the components that are perpendicular to the line of sight. These components are typically estimated using methods based on local correlation tracking. We have designed DeepVel, an end-to-end deep neural network that produces an estimation of the velocity at every single pixel, every time step, and at three different heights in the atmosphere from just two consecutive continuum images. We confront DeepVel with local correlation tracking, pointing out that they give very similar results in the time and spatially averaged cases. We use the network to study the evolution in height of the horizontal velocity field in fragmenting granules, supporting the buoyancy-braking mechanism for the formation of integranular lanes in these granules. We also show that DeepVel can capture very small vortices, so that we can potentially expand the scaling cascade of vortices to very small sizes and durations. The movie attached to Fig. 3 is available at http://www.aanda.org

  20. Free-surface velocity measurements of plates driven by reacting and detonating RX-03-BB and PBX-0404

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, L.M.; Palmer, H.G.; Parker, N.L.; Vantine, H.C.

    1981-07-13

    Copper plates 90 mm in diameter, of thickness 0.25 mm and 0.5 mm, were accelerated by an adjacent 17 mm thick cylinder of RX-03-BB or PBX-9404-03. The explosive was initiated by impact of a thick flyer from the LLNL 102 mm gun, providing either a reactive or fully detonating wave, by appropriate choice of flyer velocities up to 1.30 mm/..mu..s. The free surface velocity of the plates were measured with a Fabry-Perot velocimeter. Excellent experimental free-surface velocity histories have been obtained. Calculations of this history employing beta-burn and nucleation and growth high explosives models are in good agreement with fully detonating experiments. For reacting RX-03-BB, adjustments in the parameter are needed. The experimental technique gives records whose agreement with calculation is sensitive to the model and is therefore a good way of testing new high explosive models. Also, this method allows one to infer information about the reaction zone length.

  1. The VMC survey - XXIII. Model fitting of light and radial velocity curves of Small Magellanic Cloud classical Cepheids

    Science.gov (United States)

    Marconi, M.; Molinaro, R.; Ripepi, V.; Cioni, M.-R. L.; Clementini, G.; Moretti, M. I.; Ragosta, F.; de Grijs, R.; Groenewegen, M. A. T.; Ivanov, V. D.

    2017-04-01

    We present the results of the χ2 minimization model fitting technique applied to optical and near-infrared photometric and radial velocity data for a sample of nine fundamental and three first overtone classical Cepheids in the Small Magellanic Cloud (SMC). The near-infrared photometry (JK filters) was obtained by the European Southern Observatory (ESO) public survey 'VISTA near-infrared Y, J, Ks survey of the Magellanic Clouds system' (VMC). For each pulsator, isoperiodic model sequences have been computed by adopting a non-linear convective hydrodynamical code in order to reproduce the multifilter light and (when available) radial velocity curve amplitudes and morphological details. The inferred individual distances provide an intrinsic mean value for the SMC distance modulus of 19.01 mag and a standard deviation of 0.08 mag, in agreement with the literature. Moreover, the intrinsic masses and luminosities of the best-fitting model show that all these pulsators are brighter than the canonical evolutionary mass-luminosity relation (MLR), suggesting a significant efficiency of core overshooting and/or mass-loss. Assuming that the inferred deviation from the canonical MLR is only due to mass-loss, we derive the expected distribution of percentage mass-loss as a function of both the pulsation period and the canonical stellar mass. Finally, a good agreement is found between the predicted mean radii and current period-radius (PR) relations in the SMC available in the literature. The results of this investigation support the predictive capabilities of the adopted theoretical scenario and pave the way for the application to other extensive data bases at various chemical compositions, including the VMC Large Magellanic Cloud pulsators and Galactic Cepheids with Gaia parallaxes.

  2. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during May 2016 (NCEI Accession 0154389)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  3. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during December 2015 (NCEI Accession 0141105)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  4. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during February 2016 (NCEI Accession 0145743)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  5. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during May 2015 (NCEI Accession 0131932)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  6. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during June 2016 (NCEI Accession 0155978)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  7. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during March 2016 (NCEI Accession 0148078)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  8. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during January 2015 (NCEI Accession 0129913)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  9. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during April 2015 (NCEI Accession 0131908)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  10. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during February 2015 (NCEI Accession 0131074)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  11. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during March 2015 (NCEI Accession 0131884)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  12. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during April 2016 (NCEI Accession 0151726)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  13. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during June 2015 (NCEI Accession 0131956)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  14. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during January 2016 (NCEI Accession 0144286)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  15. Scaling properties of velocity and temperature spectra above the surface friction layer in a convective atmospheric boundary layer

    Directory of Open Access Journals (Sweden)

    K. G. McNaughton

    2007-06-01

    Full Text Available We report velocity and temperature spectra measured at nine levels from 1.42 meters up to 25.7 m over a smooth playa in Western Utah. Data are from highly convective conditions when the magnitude of the Obukhov length (our proxy for the depth of the surface friction layer was less than 2 m. Our results are somewhat similar to the results reported from the Minnesota experiment of Kaimal et al. (1976, but show significant differences in detail. Our velocity spectra show no evidence of buoyant production of kinetic energy at at the scale of the thermal structures. We interpret our velocity spectra to be the result of outer eddies interacting with the ground, not "local free convection".

    We observe that velocity spectra represent the spectral distribution of the kinetic energy of the turbulence, so we use energy scales based on total turbulence energy in the convective boundary layer (CBL to collapse our spectra. For the horizontal velocity spectra this scale is (zi εo2/3, where zi is inversion height and εo is the dissipation rate in the bulk CBL. This scale functionally replaces the Deardorff convective velocity scale. Vertical motions are blocked by the ground, so the outer eddies most effective in creating vertical motions come from the inertial subrange of the outer turbulence. We deduce that the appropriate scale for the peak region of the vertical velocity spectra is (z εo2/3 where z is height above ground. Deviations from perfect spectral collapse under these scalings at large and small wavenumbers are explained in terms of the energy transport and the eddy structures of the flow.

    We find that the peaks of the temperature spectra collapse when wavenumbers are scaled using (z1/2 zi1/2. That is, the lengths of the thermal structures depend on both the lengths of the

  16. The influence of the tangential velocity of inner rotating wall on axial velocity profile of flow through vertical annular pipe with rotating inner surface

    Directory of Open Access Journals (Sweden)

    Sharf Abdusalam M.

    2014-03-01

    Full Text Available In the oil and gas industries, understanding the behaviour of a flow through an annulus gap in a vertical position, whose outer wall is stationary whilst the inner wall rotates, is a significantly important issue in drilling wells. The main emphasis is placed on experimental (using an available rig and computational (employing CFD software investigations into the effects of the rotation speed of the inner pipe on the axial velocity profiles. The measured axial velocity profiles, in the cases of low axial flow, show that the axial velocity is influenced by the rotation speed of the inner pipe in the region of almost 33% of the annulus near the inner pipe, and influenced inversely in the rest of the annulus. The position of the maximum axial velocity is shifted from the centre to be nearer the inner pipe, by increasing the rotation speed. However, in the case of higher flow, as the rotation speed increases, the axial velocity is reduced and the position of the maximum axial velocity is skewed towards the centre of the annulus. There is a reduction of the swirl velocity corresponding to the rise of the volumetric flow rate.

  17. The influence of the tangential velocity of inner rotating wall on axial velocity profile of flow through vertical annular pipe with rotating inner surface

    Science.gov (United States)

    Sharf, Abdusalam M.; Jawan, Hosen A.; Almabsout, Fthi A.

    2014-03-01

    In the oil and gas industries, understanding the behaviour of a flow through an annulus gap in a vertical position, whose outer wall is stationary whilst the inner wall rotates, is a significantly important issue in drilling wells. The main emphasis is placed on experimental (using an available rig) and computational (employing CFD software) investigations into the effects of the rotation speed of the inner pipe on the axial velocity profiles. The measured axial velocity profiles, in the cases of low axial flow, show that the axial velocity is influenced by the rotation speed of the inner pipe in the region of almost 33% of the annulus near the inner pipe, and influenced inversely in the rest of the annulus. The position of the maximum axial velocity is shifted from the centre to be nearer the inner pipe, by increasing the rotation speed. However, in the case of higher flow, as the rotation speed increases, the axial velocity is reduced and the position of the maximum axial velocity is skewed towards the centre of the annulus. There is a reduction of the swirl velocity corresponding to the rise of the volumetric flow rate.

  18. Predictions of Planet Detections with Near-infrared Radial Velocities in the Upcoming SPIRou Legacy Survey-planet Search

    Science.gov (United States)

    Cloutier, Ryan; Artigau, Étienne; Delfosse, Xavier; Malo, Lison; Moutou, Claire; Doyon, René; Donati, Jean-Francois; Cumming, Andrew; Dumusque, Xavier; Hébrard, Élodie; Menou, Kristen

    2018-02-01

    The SPIRou near-infrared spectropolarimeter is destined to begin science operations at the Canada–France–Hawaii Telescope in mid-2018. One of the instrument’s primary science goals is to discover the closest exoplanets to the solar system by conducting a three- to five-year long radial velocity survey of nearby M dwarfs at an expected precision of ∼1 m s‑1, the SPIRou Legacy Survey-Planet Search (SLS-PS). In this study, we conduct a detailed Monte Carlo simulation of the SLS-PS using our current understanding of the occurrence rate of M dwarf planetary systems and physical models of stellar activity. From simultaneous modeling of planetary signals and activity, we predict the population of planets to be detected in the SLS-PS. With our fiducial survey strategy and expected instrument performance over a nominal survey length of ∼3 years, we expect SPIRou to detect {85.3}-12.4+29.3 planets including {20.0}-7.2+16.8 habitable-zone planets and {8.1}-3.2+7.6 Earth-like planets from a sample of 100 M1–M8.5 dwarfs out to 11 pc. By studying mid-to-late M dwarfs previously inaccessible to existing optical velocimeters, SPIRou will put meaningful constraints on the occurrence rate of planets around those stars including the value of {η }\\oplus at an expected level of precision of ≲ 45 % . We also predict that a subset of {46.7}-6.0+16.0 planets may be accessible with dedicated high-contrast imagers on the next generation of extremely large telescopes including {4.9}-2.0+4.7 potentially imagable Earth-like planets. Lastly, we compare the results of our fiducial survey strategy to other foreseeable survey versions to quantify which strategy is optimized to reach the SLS-PS science goals. The results of our simulations are made available to the community on GitHub (https://github.com/r-cloutier/SLSPS_Simulations).

  19. Study of the velocity field of surface currents in the South Atlantic Ocean derived from drifting buoy data

    Directory of Open Access Journals (Sweden)

    Eduardo Marone

    2011-12-01

    Full Text Available A total of 1442 data series of 996 drifters from public and research databases were analyzed in order to decompose and to estimate the velocity field of surface currents between 30º S and 50º S in the South Atlantic Ocean, with emphasis on the South Atlantic Current (SAC. The SAC is the southernmost limit of the South Atlantic Subtropical Gyre and presents strong interaction with other currents such as the Antarctic Circumpolar Current (ACC. The data were processed according to the Taylor's theory. The velocity field map for the study area as well as the mean values of the current intensity and associated standard deviation are presented and discussed. The highest estimated values of the average current velocity are located at the origin of the SAC and at the Malvinas Current (MC. The mean intensity of the SAC is approximately 30 cm.s-1 and the highest intensity values are observed at its origin decaying towards east. The SAC comprises a system containing a main axis and two branches, north and south. The N-SAC feeds the Benguela Current and the S-SAC leaks to the east towards the Indian Ocean. The flow pattern observed for the SAC presents a meandering characteristics and high variability in the regions where it interacts with other currents and mesoscale features.

  20. Organic solar cell efficiencies under the aspect of reduced surface recombination velocities

    OpenAIRE

    Wagenpfahl, A.; Deibel, C.; V. Dyakonov

    2010-01-01

    The charge carrier mobility is a key parameter for the organic bulk heterojunction solar cell efficiency. It was recently shown that the interplay charge carrier transport and recombination, both depending on electron and hole mobilities, leads to a point of maximum power conversion efficiency at a finite mobility. Changes of bulk and surface recombination rate, however, can strongly influence this behavior. These processes were previously not considered adequately, as surface recombination v...

  1. Effect of Relative Velocity Between Rough Surfaces: Hydrodynamic Lubrication of Rotary Lip Seal

    Science.gov (United States)

    Lahjouji, I.; Gadari, M. El; Fahime, B. El; Radouani, M.

    2017-05-01

    Since the sixties, most of numerical studies that model the rotary lip seal lubrication have been restricted by assuming that one of the two opposing surfaces is smooth: either the lip or the shaft. This hypothesis, although it is verified only for a shaft roughness ten times smaller than that of the seal, is the best solution to avoid the transient term "∂h/∂t" in the deterministic approach. Thus, the subject of the present study is twofold. The first part validates the current hydrodynamic model with the international literature by assuming the asperities on the lip and shaft as a two-dimensional cosine function. In the second part the Reynolds equation for rough surfaces with relative motion is solved. The numerical results show that the relative motion between rough surfaces impacts significantly the load support and the leakage rate, but affects slightly the friction torque.

  2. Hydraulics and drones: observations of water level, bathymetry and water surface velocity from Unmanned Aerial Vehicles

    DEFF Research Database (Denmark)

    Bandini, Filippo

    extensive research and funding, they are far less expensive and therefore more important than disaster restoration and remediation. Thus, our research question was “Can we retrieve hydraulic observations of inland surface water bodies, whenever and wherever it is required, with (i) high accuracy, (ii) high...... in monitoring surface water bodies, at a limited cost and with high flexibility. This PhD project investigates and demonstrates how UAVs can enrich the set of available hydraulic observations in inland water bodies, including: 1. Orthometric water level. 2. Water depth (bathymetry). 3. Surface water speed...... to satellites, UAVs have several advantages: high spatial resolution, repeatability of the flight missions and good tracking of the water bodies. Nevertheless, UAVs face several constraints: vibrations, limited size, weight, and electric power available for the sensors. In this thesis, we present the first...

  3. Effect of Curved Surface Shape and Feed Velocity on Microstructure and Mechanical Performance of Gray Cast Iron After Spot Continual Induction Hardening

    Science.gov (United States)

    Gao, Kai; Qin, Xunpeng; Chen, Xuliang; Wang, Zhou; Zhu, Zhenhua; Cheng, Man

    2017-05-01

    Spot continual induction hardening (SCIH) is a surface heat treatment process, which can strengthen more than one small area or relative large area on complicated component surface. In order to investigate the microstructure and mechanical properties of gray cast iron with curved surface after SCIH, the microstructure, microhardness and residual stresses were analyzed under different process conditions. The results showed that the martensite grain in hardened region of concave surface was larger than that of convex surface. The domain sizes of concave and convex surfaces were smaller than that of matrix region due to the high heating rate in SCIH process. The phase transformation depth increased with the increasing of convex surface radius but decreased with the increasing of concave surface radius. The maximum values of residual tensile and compressive stresses increased with the increasing of feed velocity for convex and concave surfaces, respectively. The appearance positions of maximum tensile and compressive stresses were closer to center for convex and concave surfaces, respectively, when feed velocity increased from 1 to 5 mm/s. The achieved results indicated that the SCIH with relatively low feed velocity was more suitable for improving the mechanical properties of gray cast iron. Compared with convex surface, the concave surface of workpiece can obtain better mechanical properties under the same feed velocity of inductor.

  4. Surface Tension Flows inside Surfactant-Added Poly(dimethylsiloxane Microstructures with Velocity-Dependent Contact Angles

    Directory of Open Access Journals (Sweden)

    Jyh Jian Chen

    2014-03-01

    Full Text Available Filling of liquid samples is realized in a microfluidic device with applications including analytical systems, biomedical devices, and systems for fundamental research. The filling of a disk-shaped polydimethylsiloxane (PDMS microchamber by liquid is analyzed with reference to microstructures with inlets and outlets. The microstructures are fabricated using a PDMS molding process with an SU-8 mold. During the filling, the motion of the gas-liquid interface is determined by the competition among inertia, adhesion, and surface tension. A single ramp model with velocity-dependent contact angles is implemented for the accurate calculation of surface tension forces in a three-dimensional volume-of-fluid based model. The effects of the parameters of this functional form are investigated. The influences of non-dimensional parameters, such as the Reynolds number and the Weber number, both determined by the inlet velocity, on the flow characteristics are also examined. An oxygen-plasma-treated PDMS substrate is utilized, and the microstructure is modified to be hydrophilic. Flow experiments are conducted into both hydrophilic and hydrophobic PDMS microstructures. Under a hydrophobic wall condition, numerical simulations with imposed boundary conditions of static and dynamic contact angles can successfully predict the moving of the meniscus compared with experimental measurements. However, for a hydrophilic wall, accurate agreement between numerical and experimental results is obvious as the dynamic contact angles were implemented.

  5. Tsunami waveform inversion for sea surface displacement following the 2011 Tohoku Earthquake: Importance of dispersion and variable rupture velocity

    Science.gov (United States)

    Cummins, P. R.; Hossen, M. J.; Dettmer, J.; Baba, T.

    2015-12-01

    This presentation considers the importance of model parametrization, including dispersion, source kinematics and source discretization, in tsunami source inversion. We implement single and multiple time window methods for dispersive and non-dispersive wave propagation to estimate source models for the tsunami generated by the 2011 Tohoku-oki earthquake. Our source model is described by sea surface displacement instead of fault slip, since sea surface displacement accounts for various tsunami generation mechanisms in addition to fault slip. The results show that tsunami source models can strongly depend on such model choices, particularly when high-quality, open-ocean tsunami waveform data are available. We carry out several synthetic inversion tests to validate the method and assess the impact of parametrization including dispersion and variable rupture velocity in data predictions on the inversion results. Although each of these effects have been considered separately in previous studies, we show that it is important to consider them together in order to obtain more meaningful inversion results. Our results suggest that the discretization of the source, the use of dispersive waves, and accounting for source kinematics are all important factors in tsunami source inversion of large events such as the Tohoku-oki earthquake, particularly when an extensive set of high quality tsunami waveform recordings are available. For the Tohoku event, a dispersive model with variable rupture velocity results in a profound improvement in waveform fits that justify the higher source complexity and provide a more realistic source model.

  6. Near-surface velocity modeling at Yucca Mountain using borehole and surface records from underground nuclear explosions

    Energy Technology Data Exchange (ETDEWEB)

    Durrani, B.A. [Texas Univ., El Paso, TX (United States). Dept. of Geological Sciences; Walck, M.C. [Sandia National Labs., Albuquerque, NM (United States)

    1996-09-01

    The Department of Energy is investigating Yucca Mountain, Nevada as a potential site for commercial radioactive waste disposal in a mined geologic repository. One critical aspect of site suitability is the tectonic stability of the repository site. The levels of risk from both actual fault displacements in the repository block and ground shaking from nearby earthquakes are being examined. In particular, it is necessary to determine the expected level of ground shaking at the repository depth for large seismic sources such as nearby large earthquakes or underground nuclear explosions (UNEs). Earthquakes are expected to cause the largest ground motions at the site, however, only underground nuclear explosion data have been obtained at the repository depth level (about 350m below the ground level) to date. In this study we investigate ground motion from Nevada Test Site underground nuclear explosions recorded at Yucca Mountain to establish a compressional velocity model for the uppermost 350m of the mountain. This model is useful for prediction of repository-level ground motions for potential large nearby earthquakes.

  7. Retrieval of sea surface velocities using sequential ocean colour monitor (OCM) data

    Digital Repository Service at National Institute of Oceanography (India)

    Prasad, J.S.; Rajawat, A.S.; Pradhan, Y.; Chauhan, O.S.; Nayak, S.R.

    parameters like chlorophyll-a, suspended sediments, yellow substance and aerosol optical depth at regional scale. Sequential data of IRS-P4 OCM has been analysed over parts of both east and west coast of India and a methodology to retrieve sea surface current...

  8. Mapping the Agulhas Current from space: an assessment of ASAR surface current velocities

    CSIR Research Space (South Africa)

    Rouault, MJ

    2010-10-01

    Full Text Available Over 2 years of surface current information collected in the Agulhas Current region and derived from the Doppler centroid anomalies of Envisat’s advanced synthetic aperture radar (ASAR) are examined. The sources of errors and potential use of ASAR...

  9. The influence of surface on the running velocities of elite and amateur orienteer athletes

    DEFF Research Database (Denmark)

    Hébert-Losier, K; Jensen, Kurt; Mourot, L

    2014-01-01

    "all-out" on a road, on a path, and in a forest. On a third day, the running economy and maximal aerobic power of individuals were assessed on a treadmill. The elite orienteer ran faster than the amateur on all three surfaces and at both distances, in line with their better running economy and aerobic...

  10. Planar time-resolved PIV for velocity and pressure retrieval in atmospheric boundary layer over surface waves.

    Science.gov (United States)

    Troitskaya, Yuliya; Kandaurov, Alexander; Sergeev, Daniil; Bopp, Maximilian; Caulliez, Guillemette

    2017-04-01

    Air-sea coupling in general is important for weather, climate, fluxes. Wind wave source is crucially important for surface waves' modeling. But the wind-wave growth rate is strongly uncertain. Using direct measurements of pressure by wave-following Elliott probe [1] showed, weak and indefinite dependence of wind-wave growth rate on the wave steepness, while Grare et.al. [2] discuss the limitations of direct measurements of pressure associated with the inability to measure the pressure close to the surface by contact methods. Recently non-invasive methods for determining the pressure on the basis of technology of time-resolved PIV are actively developed [3]. Retrieving air flow velocities by 2D PIV techniques was started from Reul et al [4]. The first attempt for retrieving wind pressure field of waves in the laboratory tank from the time-resolved PIV measurements was done in [5]. The experiments were performed at the Large Air-Sea Interaction Facility (LASIF) - MIO/Luminy (length 40 m, cross section of air channel 3.2 x 1.6 m). For 18 regimes with wind speed up to 14 m/s including presence of puddle waves, a combination of time resolved PIV technique and optical measurements of water surface form was applied to detailed investigation of the characteristics of the wind flow over the water surface. Ammonium chloride smoke was used for flow visualization illuminated by two 6 Wt blue diode lasers combined into a vertical laser plane. Particle movement was captured with high-speed camera using Scheimpflug technique (up to 20 kHz frame rate with 4-frame bursts, spatial resolution about 190 μm, field of view 314x12 mm). Velocity air flow field was retrieved by PIV images processing with adaptive cross-correlation method on the curvilinear grid following surface wave form. The resulting time resolved instantaneous velocity fields on regular grid allowed us to obtain momentum fluxes directly from measured air velocity fluctuations. The average wind velocity patterns were

  11. Very low surface recombination velocities on 2.5 {omega}cm Si wafers, obtained with low-temperature PECVD of Si-oxide and Si-nitride

    Energy Technology Data Exchange (ETDEWEB)

    Leguijt, C.; Loelgen, P. [FOM-Institute for Atomic and Molecular Physics, Amsterdam (Netherlands); Eikelboom, J.A.; Amesz, P.H.; Steeman, R.A.; Sinke, W.C. [Unit ECN Renewable Energy, Netherlands Energy Research Foundation, Petten (Netherlands); Sarro, P.M. [Delft Institute for Micro-Electronics and Submicron technology DIMES, Delft (Netherlands); Verhoef, L.A.; Michiels, P.-P. [R and S Renewable Energy Systems BV, Helmond (Netherlands); Chen, Z.H.; Rohatgi, A. [Univerisity Centre Of Excellence for Photovoltaics Research and Education, Georgia Institute of Technology, Atlanta, GA (United States)

    1993-09-01

    The first measurements are presented of very low recombination velocities (<90 cm/s) on 2.5 {omega}cm p-type silicon wafers, passivated with low-temperature PECVD (Plasma Enhanced Chemical Vapor Deposition) of Si-oxide and Si-nitride. Also n-type emitter surfaces were passivated by PECVD. A forming gas anneal turned out to be crucial in achieving low recombination velocities. No increase of the surface recombination velocity was observed after exposure of the layers to white light at 30{sup o}C and 1000 W/m{sup 2} for 500 hours. 16 refs.

  12. Skin surface brachytherapy: A survey of contemporary practice patterns.

    Science.gov (United States)

    Likhacheva, Anna O; Devlin, Phillip M; Shirvani, Shervin M; Barker, Christopher A; Beron, Phillip; Bhatnagar, Ajay; Doggett, Stephen W; Hochman, Lawrence; Hsu, Charles; Kasper, Michael; Keisch, Martin; Mutyala, Subhakar; Prestidge, Bradley; Rodriguez Villalba, Silvia; Shukla, Vershalee; Sundararaman, Srinath; Kamrava, Mitchell

    The aim of this study was to define current patterns of care among radiation oncologists who use skin surface brachytherapy for the treatment of cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC) in academic and community settings. A 30-question electronic survey was administered to clinician members of the American Brachytherapy Society. The respondents were asked to provide details regarding their clinical practice and their approach to skin surface brachytherapy. A total of 16 surveys were returned. Among the respondents, aggregate experience varied from 8 to 1800 cases. Most preferred brachytherapy over external beam radiation because of shorter treatment course, conformality of treatment for irregular or curved targets, and shallow dose deposition. Of the total, 60% of respondents routinely estimated lesion depth via ultrasound before initiating treatment. Treatment margin on gross disease varied widely (range, 3-15 mm; median, 5 mm). Hypofractionation was the preferred dose schedule. Prescribed doses ranged from 30 Gy in five fractions to 64 Gy in 32 fractions (EQD2, 40 Gy-65 Gy). There was a tendency to increase the number of fractions for larger targets, although some used the same fractionation regardless of anatomic location or lesion size. There was no consensus on dosimetric constraints, and some respondents reported cases of severe toxicity, particularly when treating the pretibial skin. This pattern of care study suggests that skin brachytherapy can be a convenient and safe tool for treatment of BCC and cSCC. Prospective trials and the development of expert consensus guidelines would be beneficial for optimizing skin surface brachytherapy and reducing practice variation. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  13. Sublimation pit distribution indicates convection cell surface velocities of ∼10 cm per year in Sputnik Planitia, Pluto

    Science.gov (United States)

    Buhler, Peter B.; Ingersoll, Andrew P.

    2018-01-01

    The ∼106 km2 Sputnik Planitia, Pluto is the upper surface of a vast basin of nitrogen ice. Cellular landforms in Sputnik Planitia with areas in the range of a few × 102-103 km2 are likely the surface manifestation of convective overturn in the nitrogen ice. The cells have sublimation pits on them, with smaller pits near their centers and larger pits near their edges. We map pits on seven cells and find that the pit radii increase by between 2.1 ± 0.4 × 10-3 and 5.9 ± 0.8 × 10-3 m m-1 away from the cell center, depending on the cell. This is a lower bound on the size increase because of the finite resolution of the data. Accounting for resolution yields upper bounds on the size vs. distance distribution of between 4.2 ± 0.2 × 10-3 and 23.4 ± 1.5 × 10-3 m m-1. We then use an analytic model to calculate that pit radii grow via sublimation at a rate of 3.6-0.6+2.1 ×10-4 m yr-1, which allows us to convert the pit size vs. distance distribution into a pit age vs. distance distribution. This yields surface velocities between 1.5-0.2+1.0 and 6.2-1.4+3.4 cm yr-1 for the slowest cell and surface velocities between 8.1-1.0+5.5 and 17.9-5.1+8.9 cm yr-1 for the fastest cell. These convection rates imply that the surface ages at the edge of cells reach ∼4.2-8.9 × 105 yr. The rates are comparable to rates of ∼6 cm yr-1 that were previously obtained from modeling of the convective overturn in Sputnik Planitia (McKinnon et al., 2016). Finally, we investigate the surface rheology of the convection cells and estimate that the minimum ice viscosity necessary to support the geometry of the observed pits is of order 1016-1017 Pa s, based on the argument that pits would relax away before growing to their observed radii of several hundred meters if the viscosity were lower than this value.

  14. Surface wave tomography of North America and the Caribbean using global and regional broad-band networks: Phase velocity maps and limitations of ray theory

    Science.gov (United States)

    Godey, S.; Snieder, R.; Villasenor, A.; Benz, H.M.

    2003-01-01

    We present phase velocity maps of fundamental mode Rayleigh waves across the North American and Caribbean plates. Our data set consists of 1846 waveforms from 172 events recorded at 91 broad-band stations operating in North America. We compute phase velocity maps in four narrow period bands between 50 and 150 s using a non-linear waveform inversion method that solves for phase velocity perturbations relative to a reference Earth model (PREM). Our results show a strong velocity contrast between high velocities beneath the stable North American craton, and lower velocities in the tectonically active western margin, in agreement with other regional and global surface wave tomography studies. We perform detailed comparisons with global model results, which display good agreement between phase velocity maps in the location and amplitude of the anomalies. However, forward modelling shows that regional maps are more accurate for predicting waveforms. In addition, at long periods, the amplitude of the velocity anomalies imaged in our regional phase velocity maps is three time larger than in global phase velocity models. This amplitude factor is necessary to explain the data accurately, showing that regional models provide a better image of velocity structures. Synthetic tests show that the raypath coverage used in this study enables one to resolve velocity features of the order of 800-1000 km. However, only larger length-scale features are observed in the phase velocity maps. The limitation in resolution of our maps can be attributed to the wave propagation theory used in the inversion. Ray theory does not account for off-great-circle ray propagation effects, such as ray bending or scattering. For wavelengths less than 1000 km, scattering effects are significant and may need to be considered.

  15. Deriving inertial wave characteristics from surface drifter velocities: Frequency variability in the Tropical Pacific

    Science.gov (United States)

    Poulain, Pierre-Marie; Luther, Douglas S.; Patzert, William C.

    1992-11-01

    Two techniques have been developed for estimating statistics of inertial oscillations from satellite-tracked drifters. These techniques overcome the difficulties inherent in estimating such statistics from data dependent upon space coordinates that are a function of time. Application of these techniques to tropical surface drifter data collected during the NORPAX, EPOCS, and TOGA programs reveals a latitude-dependent, statistically significant "blue shift" of inertial wave frequency. The latitudinal dependence of the blue shift is similar to predictions based on "global" internal wave spectral models, with a superposition of frequency shifting due to modification of the effective local inertial frequency by the presence of strongly sheared zonal mean currents within 12° of the equator.

  16. Sputnik Planitia, Pluto Convection Cell Surface Velocities of ~10 Centimeters per Year Based on Sublimation Pit Distribution

    Science.gov (United States)

    Buhler, Peter Benjamin; Ingersoll, Andrew P.

    2017-10-01

    Sputnik Planitia, Pluto contains cellular landforms with areas on the order of a few 102-103 km2 that are likely the surface manifestation of convective overturn in a vast basin of nitrogen ice. The cells have sublimation pits on them, with smaller pits near their centers and larger pits near their edges. We map over 12,000 pits on seven cells and find that the pit radii increase by between 2.1 ± 0.4 and 5.9 ± 0.8 × 10-3 m per meter away from the cell center, depending on the cell. Due to finite data resolution, this is a lower bound on the size increase. Conservatively accounting for resolution effects yields upper bounds on the size vs. distance distribution of 4.2 ± 0.2 to 23.4 ± 1.5 × 10-3 m m-1. In order to convert the pit size vs. distance distribution into a pit age vs. distance distribution, we use an analytic model to calculate that pit radii grow via sublimation at a rate of 3.6 [+2.1,-0.6] × 10-4 m yr-1. Combined with the mapped distribution of pit radii, this yields surface velocities between 1.5 [+1.0,-0.2] and 6.2 [+3.4,-1.4] cm yr-1 for the slowest cell and surface velocities between 8.1 [+5.5,-1.0] and 17.9 [+8.9,-5.1] cm yr-1 for the fastest cell; the lower bound estimate for each cell accounts for resolution effects, while the upper bound estimate does not. These convection rates imply that the surface ages at the edge of cells reach approximately 4.2 to 8.9 × 105 yr, depending on the cell. The rates we find are comparable to rates of ~6 cm yr-1 that were previously obtained from modeling of the convective overturn in Sputnik Planitia [McKinnon, W.B. et al., 2016, Nature, 534(7605), 82-85]. Finally, we find that the minimum viscosity at the surface of the convection cells is of order 1016 to 1017 Pa s; we find that pits would relax away before sublimating to their observed radii of several hundred meters if the viscosity were lower than this value.

  17. Thermal and force loads on the vehicle surface in high-velocity motion in the earth's atmosphere

    Science.gov (United States)

    Tarnavskii, G. A.

    2008-03-01

    Consideration has been given to a number of aspects of mathematical modeling of a high-velocity flight in the earth’s atmosphere in a wide range of variation of the determining parameters. Super-and hypersonic gas flow past flying vehicles has been investigated based on computer-aided calculations with allowance for its actual properties. Data on the distribution of gasdynamic parameters in the flow field, including thermal and force loads on the surface, have been obtained and analyzed. The issues of applying today’s information technologies to archiving scientific knowledge obtained in electronic databases of a specialized Internet center and their dissemination via the Global Network have been discussed.

  18. Stagnation point flow on bioconvection nanofluid over a stretching/shrinking surface with velocity and thermal slip effects

    Science.gov (United States)

    Chan, Sze Qi; Aman, Fazlina; Mansur, Syahira

    2017-09-01

    Nanofluid containing nanometer sized particles has become an ideal thermal conductivity medium for the flow and heat transfer in many industrial and engineering applications due to their high rate of heat transfer. However, swimming microorganisms are imposed into the nanofluid to overcome the instability of nanoparticles due to a bioconvection phenomenon. This paper investigates the stagnation point flow on bioconvection heat transfer of a nanofluid over a stretching/shrinking surface containing gyrotactic microorganisms. Velocity and thermal slip effects are the two conditions incorporated into the model. Similarity transformation is applied to reduce the governing nonlinear partial differential equations into the nonlinear ordinary differential equations. The transformed equations are then solved numerically. The results are displayed in the form of graphs and tables. The effects of these governing parameters on the skin friction coefficient, local Nusselt number, local Sherwood number and the local density of the motile microorganisms are analysed and discussed in details.

  19. Incorporation of velocity-dependent restitution coefficient and particle surface friction into kinetic theory for modeling granular flow cooling

    Science.gov (United States)

    Duan, Yifei; Feng, Zhi-Gang

    2017-12-01

    Kinetic theory (KT) has been successfully used to model rapid granular flows in which particle interactions are frictionless and near elastic. However, it fails when particle interactions become frictional and inelastic. For example, the KT is not able to accurately predict the free cooling process of a vibrated granular medium that consists of inelastic frictional particles under microgravity. The main reason that the classical KT fails to model these flows is due to its inability to account for the particle surface friction and its inelastic behavior, which are the two most important factors that need be considered in modeling collisional granular flows. In this study, we have modified the KT model that is able to incorporate these two factors. The inelasticity of a particle is considered by establishing a velocity-dependent expression for the restitution coefficient based on many experimental studies found in the literature, and the particle friction effect is included by using a tangential restitution coefficient that is related to the particle friction coefficient. Theoretical predictions of the free cooling process by the classical KT and the improved KT are compared with the experimental results from a study conducted on an airplane undergoing parabolic flights without the influence of gravity [Y. Grasselli, G. Bossis, and G. Goutallier, Europhys. Lett. 86, 60007 (2009), 10.1209/0295-5075/86/60007]. Our results show that both the velocity-dependent restitution coefficient and the particle surface friction are important in predicting the free cooling process of granular flows; the modified KT model that integrates these two factors is able to improve the simulation results and leads to better agreement with the experimental results.

  20. Magnetohydrodynamic and thermal radiation effects on the boundary-layer flow due to a moving extensible surface with the velocity slip model: A comparative study of four nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Aly, Emad H., E-mail: efarag@uj.edu.sa [Department of Mathematics, Faculty of Science, University of Jeddah, Jeddah 21589 (Saudi Arabia); Department of Mathematics, Faculty of Education, Ain Shams University, Roxy, Cairo 11757 (Egypt); Sayed, Hamed M. [Department of Mathematics, Faculty of Education, Ain Shams University, Roxy, Cairo 11757 (Egypt); Department of Mathematics, Faculty of Sciences, Taibah University, Yanbu (Saudi Arabia)

    2017-01-15

    In the current work, we investigated effects of the velocity slip for the flow and heat transfer of four nanofluids over a non-linear stretching sheet taking into account the thermal radiation and magnetic field in presence of the effective electrical conductivity. The governing partial differential equations were transformed into a set of nonlinear ordinary differential equation using similarity transformations before being solved numerically by the Chebyshev pseudospectral differentiation matrix (ChPDM). It was found that the investigated parameters affect remarkably on the nanofluid stream function for the whole investigated nanoparticles. In addition, velocity and skin friction profiles of the four investigated nanofluids decreases and increases, respectively, with the increase of the magnetic parameter, first-order and second-order velocity slips. Further, the flow velocity, surface shear stress and temperature are strongly influenced on applying the velocity slip model, where lower values of the second-order imply higher surface heat flux and thereby making the fluid warmer. - Highlights: • A comparative study for four nanoparticles with MHD and thermal radiation effects was studied. • The effective electrical conductivity is mandatory; otherwise a spurious physical sight will be gained. • The investigated parameters affect remarkably on the nanofluids' flow. • The flow velocity, surface shear stress and temperature are strongly influenced by the slip model. • Lower values of the second-order imply higher surface heat flux and thereby making the fluid warmer.

  1. The Surface Velocity Structure of the Florida Current in a Jet Coordinate Frame

    Science.gov (United States)

    Archer, Matthew R.; Shay, Lynn K.; Johns, William E.

    2017-11-01

    The structure and variability of the Florida Current between 25° and 26°N are investigated using HF radar ocean current measurements to provide the most detailed view of the surface jet to date. A 2-D jet coordinate analysis is performed to define lateral displacements of the jet in time (meandering), and associated structural variations over a 2 year period (2005-2006). In the jet coordinate frame, core speed has a median value of ˜160 cm s-1 at the central latitude of the array (25.4°N), with a standard deviation (STD) of 35 cm s-1. The jet meanders at timescales of 3-30 days, with a STD of 8 km, and a downstream phase speed of ˜80 km d-1. Meandering accounts for ˜45% of eddy kinetic energy computed in a fixed (geographical) reference frame. Core speed, width, and shear undergo the same dominant 3-30 day variability, plus an annual cycle that matches seasonality of alongshore wind stress. Jet transport at 25.4°N exhibits a different seasonality to volume transport at 27°N, most likely driven by input from the Northwest Providence Channel. Core speed correlates inversely with Miami sea level fluctuations such that a 40 cm s-1 deceleration is associated with a ˜10 cm elevation in sea level, although there is no correlation of sea level to jet meandering or width. Such accurate quantification of the Florida Current's variability is critical to understand and forecast future changes in the climate system of the North Atlantic, as well as local impacts on coastal circulation and sea level variability along south Florida's coastline.

  2. Elbow joint angle and elbow movement velocity estimation using NARX-multiple layer perceptron neural network model with surface EMG time domain parameters.

    Science.gov (United States)

    Raj, Retheep; Sivanandan, K S

    2017-01-01

    Estimation of elbow dynamics has been the object of numerous investigations. In this work a solution is proposed for estimating elbow movement velocity and elbow joint angle from Surface Electromyography (SEMG) signals. Here the Surface Electromyography signals are acquired from the biceps brachii muscle of human hand. Two time-domain parameters, Integrated EMG (IEMG) and Zero Crossing (ZC), are extracted from the Surface Electromyography signal. The relationship between the time domain parameters, IEMG and ZC with elbow angular displacement and elbow angular velocity during extension and flexion of the elbow are studied. A multiple input-multiple output model is derived for identifying the kinematics of elbow. A Nonlinear Auto Regressive with eXogenous inputs (NARX) structure based multiple layer perceptron neural network (MLPNN) model is proposed for the estimation of elbow joint angle and elbow angular velocity. The proposed NARX MLPNN model is trained using Levenberg-marquardt based algorithm. The proposed model is estimating the elbow joint angle and elbow movement angular velocity with appreciable accuracy. The model is validated using regression coefficient value (R). The average regression coefficient value (R) obtained for elbow angular displacement prediction is 0.9641 and for the elbow anglular velocity prediction is 0.9347. The Nonlinear Auto Regressive with eXogenous inputs (NARX) structure based multiple layer perceptron neural networks (MLPNN) model can be used for the estimation of angular displacement and movement angular velocity of the elbow with good accuracy.

  3. System and method for investigating sub-surface features and 3D imaging of non-linear property, compressional velocity VP, shear velocity VS and velocity ratio VP/VS of a rock formation

    Science.gov (United States)

    Vu, Cung Khac; Skelt, Christopher; Nihei, Kurt; Johnson, Paul A.; Guyer, Robert; Ten Cate, James A.; Le Bas, Pierre-Yves; Larmat, Carene S.

    2015-06-02

    A system and a method for generating a three-dimensional image of a rock formation, compressional velocity VP, shear velocity VS and velocity ratio VP/VS of a rock formation are provided. A first acoustic signal includes a first plurality of pulses. A second acoustic signal from a second source includes a second plurality of pulses. A detected signal returning to the borehole includes a signal generated by a non-linear mixing process from the first and second acoustic signals in a non-linear mixing zone within an intersection volume. The received signal is processed to extract the signal over noise and/or signals resulting from linear interaction and the three dimensional image of is generated.

  4. The Radial Velocity Experiment (RAVE) : First data release

    NARCIS (Netherlands)

    Steinmetz, M.; Zwitter, T.; Siebert, A.; Watson, F. G.; Freeman, K. C.; Munari, U.; Campbell, R.; Williams, M.; Seabroke, G. M.; Wyse, R. F. G.; Parker, Q. A.; Bienayme, O.; Roeser, S.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Navarro, J. F.; Burton, D.; Cass, C. J. P.; Dawe, J. A.; Fiegert, K.; Hartley, M.; Russell, K. S.; Saunders, W.; Enke, H.; Bailin, J.; Binney, J.; Bland-Hawthorn, J.; Boeche, C.; Dehnen, W.; Eisenstein, D. J.; Evans, N. W.; Fiorucci, M.; Fulbright, J. P.; Gerhard, O.; Jauregi, U.; Kelz, A.; Mijovic, L.; Minchev, I.; Parmentier, G.; Penarrubia, J.; Quillen, A. C.; Read, M. A.; Ruchti, G.; Scholz, R. -D.; Siviero, A.; Smith, M.C.; Sordo, R.; Veltz, L.; Vidrih, S.; von Berlepsch, R.; Boyle, B. J.; Schilbach, E.; Helmi, A.

    2006-01-01

    We present the first data release of the Radial Velocity Experiment (RAVE), an ambitious spectroscopic survey to measure radial velocities and stellar atmosphere parameters (temperature, metallicity, and surface gravity) of up to one million stars using the Six Degree Field multiobject spectrograph

  5. Techniques for Surface-Temperature Measurements and Transition Detection on Projectiles at Hypersonic Velocities--Status Report No. 2

    Science.gov (United States)

    Bogdanoff, D. W.; Wilder, M. C.

    2006-01-01

    The latest developments in a research effort to advance techniques for measuring surface temperatures and heat fluxes and determining transition locations on projectiles in hypersonic free flight in a ballistic range are described. Spherical and hemispherical titanium projectiles were launched at muzzle velocities of 4.6-5.8 km/sec into air and nitrogen at pressures of 95-380 Torr. Hemisphere models with diameters of 2.22 cm had maximum pitch and yaw angles of 5.5-8 degrees and 4.7-7 degrees, depending on whether they were launched using an evacuated launch tube or not. Hemisphere models with diameters of 2.86 cm had maximum pitch and yaw angles of 2.0-2.5 degrees. Three intensified-charge-coupled-device (ICCD) cameras with wavelength sensitivity ranges of 480-870 nm (as well as one infrared camera with a wavelength sensitivity range of 3 to 5 microns), were used to obtain images of the projectiles in flight. Helium plumes were used to remove the radiating gas cap around the projectiles at the locations where ICCD camera images were taken. ICCD and infrared (IR) camera images of titanium hemisphere projectiles at velocities of 4.0-4.4 km/sec are presented as well as preliminary temperature data for these projectiles. Comparisons were made of normalized temperature data for shots at approx.190 Torr in air and nitrogen and with and without the launch tube evacuated. Shots into nitrogen had temperatures 6% lower than those into air. Evacuation of the launch tube was also found to lower the projectile temperatures by approx.6%.

  6. SWFSC FED Mid Water Trawl Juvenile Rockfish Survey, Surface Data, 1987-2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC FED Mid Water Trawl Juvenile Rockfish Survey: Station Information and Surface Data. Surveys have been conducted along the central California coast in May/June...

  7. Characterization Investigation Study: Volume 3, Radiological survey of surface soils

    Energy Technology Data Exchange (ETDEWEB)

    Solow, A.J.; Phoenix, D.R.

    1987-12-01

    The Feed Materials Production Center was constructed to produce high purity uranium metal for use at various Department of Energy facilities. The waste products from these operations include general uncontaminated scrap and refuse, contaminated and uncontaminated metal scrap, waste oils, low-level radioactive waste, co-contaminated wastes, mixed waste, toxic waste, sludges from water treatment, and fly ash from the steam plant. This material is estimated to total more than 350,000 cubic meters. Other wastes stored in this area include laboratory chemicals and other combustible materials in the burn pit; fine waste stream sediments in the clear well; fly ash and waste oils in the two fly ash areas; lime-alum sludges and boiler plant blowdown in the lime sludge ponds; and nonradioactive sanitary waste, construction rubble, and asbestos in the sanitary landfill. A systematic survey of the surface soils throughout the Waste Storage Area, associated on-site drainages, and the fly ash piles was conducted using a Field Instrument for Detecting Low-Energy Radiation (FIDLER). Uranium is the most prevalent radioactive element in surface soil; U-238 is the principal radionuclide, ranging from 2.2 to 1790 pCi/g in the general Waste Storage Area. The maximum values for the next highest activity concentrations in the same area were 972 pCi/g for Th-230 and 298 pCi/g for U-234. Elevated activity concentrations of Th-230 were found along the K-65 slurry line, the maximum at 3010 pCi/g. U-238 had the highest value of 761 pCi/g in the drainage just south of pit no. 5. The upper fly ash area had the highest radionuclide activity concentrations in the surface soils with the maximum values for U-238 at 8600 pCi/g, U-235 at 2190 pCi/g, U-234 at 11,400 pCi/g, Tc-99 at 594 pCi/g, Ra-226 at 279 pCi/g, and Th-230 at 164 pCi/g.

  8. Real-Time Thermographic-Phosphor-Based Temperature Measurements of Thermal Barrier Coating Surfaces Subjected to a High-Velocity Combustor Burner Environment

    Science.gov (United States)

    Eldridge, Jeffrey I.; Jenkins, Thomas P.; Allison, Stephen W.; Cruzen, Scott; Condevaux, J. J.; Senk, J. R.; Paul, A. D.

    2011-01-01

    Surface temperature measurements were conducted on metallic specimens coated with an yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC) with a YAG:Dy phosphor layer that were subjected to an aggressive high-velocity combustor burner environment. Luminescence-based surface temperature measurements of the same TBC system have previously been demonstrated for specimens subjected to static furnace or laser heating. Surface temperatures were determined from the decay time of the luminescence signal of the YAG:Dy phosphor layer that was excited by a pulsed laser source. However, the furnace and laser heating provides a much more benign environment than that which exists in a turbine engine, where there are additional challenges of a highly radiant background and high velocity gases. As the next step in validating the suitability of luminescence-based temperature measurements for turbine engine environments, new testing was performed where heating was provided by a high-velocity combustor burner rig at Williams International. Real-time surface temperature measurements during burner rig heating were obtained from the decay of the luminescence from the YAG:Dy surface layer. The robustness of several temperature probe designs in the sonic velocity, high radiance flame environment was evaluated. In addition, analysis was performed to show whether the luminescence decay could be satisfactorily extracted from the high radiance background.

  9. Test-retest reliability of muscle fiber conduction velocity and fractal dimension of surface EMG during isometric contractions.

    Science.gov (United States)

    Beretta-Piccoli, Matteo; D'Antona, Giuseppe; Zampella, Cristian; Barbero, Marco; Clijsen, Ron; Cescon, Corrado

    2017-04-01

    The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1 week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays. Initial values and slope of CV and FD were used for the reliability analysis. The intraclass correlation coefficient (ICC) values for the isometric contraction at 20% MVC were (-0.09) and 0.67 for CV and FD respectively; whereas the ICC values at 60% MVC were 0.78 and 0.82 for CV and FD respectively. The Bland Altman plots for the two isometric contractions showed a mean difference close to zero, with no evident outliers between the repeated measurements: at 20% MVC 0.001 53 for FD and  -0.0277 for CV, and at 60% MVC 0.006 66 for FD and 0.009 07 for CV. Overall, our findings suggest that during isometric fatiguing contractions, CV and FD slopes are reliable variables, with potential application in clinical populations.

  10. Spatial and temporal variations in surface velocity and basal drag across the tongue of the polythermal glacier midre Lovénbreen, Svalbard

    Science.gov (United States)

    Rippin, D. M.; Willis, I. C.; Arnold, N. S.; Hodson, A. J.; Brinkhaus, M.

    We present results of a detailed investigation of surface motion across the tongue of a polythermal glacier, midre Lovénbreen, Svalbard, during the 1999 summer. Surface velocities in the warm-based upper tongue increased during periods of enhanced surface melting and rainfall events, and force-balance analysis indicates that these velocity variations were locally forced, probably by fluctuations in subglacial water pressure. Surface speed-ups were also observed on the cold-based lower tongue (which acted as a sticky spot, through which there was minimal subglacial drainage for most of the summer), but these were largely non-locally forced by longitudinal coupling to the faster-moving ice up-glacier. On one occasion, however, a large, rapid input of surface water to the glacier reduced the basal drag beneath the cold-based lower tongue, presumably due to hydraulic jacking. This resulted in locally forced enhanced surface velocities across the entire tongue, accompanied by a breaching of the lower tongue and an outburst of subglacially stored water.

  11. Mean velocity distribution of open channel turbulent flow on a sawtooth riblet surface. Riblet somen kaisuiro ranryu no heikin ryusoku bunpu

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T. (Yamaguchi University, Yamaguchi (Japan). Faculty of Engineering)

    1993-11-01

    The mean velocity distribution of an open channel turbulent flow on a sawtooth riblet surface. The long open channel of 60 cm wide, 25 cm deep and 10 m long was used, and equilateral triangle riblets of 2 mm in edge were laid longitudinally all over the bottom surface of the channel. Flow velocity was measured by pitot tube with a rectangular open section of 0.5 [times] 3 mm. As an experimental result, as the apparent origin of velocity profiles was evaluated assuming the presence of a viscous bottom layer, the coefficient of frictional drag agreed with previous experimental ones, however, the apparent origin descended from a riblet peak with an increase in drag reduction rate. The velocity profile in a buffer region differed remarkably from that on a smooth wall, and the maximum mixing length was found at 80-100 in non-dimensional water depth (Y[sup +]) increasing with the drag reduction rate. From a mixing length profile, as the apparent origin lay at 20-30 in Y[sup +], the logarithmic velocity profile was found in a range over 150 in Y[sup +]. 7 refs., 10 figs., 1 tab.

  12. Near-surface seismic velocity changes in a salt-dominated environment due to shaking and thermal stressing

    Science.gov (United States)

    Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter

    2014-05-01

    We report on results from a seismic station of the Integrated Plate Boundary Observatory Chile (IPOC) showing a superior sensitivity of seismic velocity changes in the surrounding medium to shaking and temperature. 5 years of daily autocorrelations of the IPOC network are analyzed with passive image interferometry. Due to the particular geological conditions we observe a high sensitivity of the medium around the station near Patache (PATCX) resulting in annual periodic velocity variations and temporary velocity reductions induced by ground shaking. We observe a linear relationship between the amplitude of the velocity reductions and the peak ground acceleration (PGA) of nearby earthquakes at station PATCX. Although velocity reductions are also observed at other stations of the IPOC array for the Mw 7.7 Tocopilla earthquake a clear relationship between the PGA of this earthquake and the induced velocity reductions at the different stations is not visible. Furthermore, we observe velocity variations with an annual and daily period. We present different arguments that these periodic changes are caused by variations of the atmospheric temperature. In this context we construct a model that starts at observed temperature variations and evaluates thermal stresses induced by the temperature gradients. Using radiative transfer based sensitivity kernels and third order elastic constants we relate the distribution of thermal stress in the subsurface to observable time shifts of coda waves. The model is able to reproduce the major features confirming that stress changes in the subsurface can be detected with noise based monitoring.

  13. Regression models of discharge and mean velocity associated with near-median streamflow conditions in Texas: utility of the U.S. Geological Survey discharge measurement database

    Science.gov (United States)

    Asquith, William H.

    2014-01-01

    A database containing more than 16,300 discharge values and ancillary hydraulic attributes was assembled from summaries of discharge measurement records for 391 USGS streamflow-gauging stations (streamgauges) in Texas. Each discharge is between the 40th- and 60th-percentile daily mean streamflow as determined by period-of-record, streamgauge-specific, flow-duration curves. Each discharge therefore is assumed to represent a discharge measurement made for near-median streamflow conditions, and such conditions are conceptualized as representative of midrange to baseflow conditions in much of the state. The hydraulic attributes of each discharge measurement included concomitant cross-section flow area, water-surface top width, and reported mean velocity. Two regression equations are presented: (1) an expression for discharge and (2) an expression for mean velocity, both as functions of selected hydraulic attributes and watershed characteristics. Specifically, the discharge equation uses cross-sectional area, water-surface top width, contributing drainage area of the watershed, and mean annual precipitation of the location; the equation has an adjusted R-squared of approximately 0.95 and residual standard error of approximately 0.23 base-10 logarithm (cubic meters per second). The mean velocity equation uses discharge, water-surface top width, contributing drainage area, and mean annual precipitation; the equation has an adjusted R-squared of approximately 0.50 and residual standard error of approximately 0.087 third root (meters per second). Residual plots from both equations indicate that reliable estimates of discharge and mean velocity at ungauged stream sites are possible. Further, the relation between contributing drainage area and main-channel slope (a measure of whole-watershed slope) is depicted to aid analyst judgment of equation applicability for ungauged sites. Example applications and computations are provided and discussed within a real-world, discharge

  14. A new scheme for joint surface wave and earthquake travel-time inversion and resulting 3-D velocity model for the western North Island, New Zealand

    Science.gov (United States)

    Eberhart-Phillips, Donna; Fry, Bill

    2017-08-01

    We have developed a joint inversion of surface wave group velocity (U) and local earthquake travel-time (LET) data and applied it to the North Island, New Zealand, to improve the existing New Zealand wide 3-D seismic velocity model. This approach takes full advantage of the differing sensitivities of surface and body waves. The data are complementary, particularly at shallow depths where LET tomography suffers from vertical smearing and surface wave tomography is susceptible to horizontal smearing. The employed U observations are 2-D models at discrete periods which were developed for Rayleigh wave dispersion curves measured from the 1744 interstation Green's Functions obtained by stacked cross-correlations of broadband ambient noise data. In the volume surrounding each U observation, we distribute numerous points for relating the U observation to the gridded 3-D tomography model, analogous to points along a raypath. The partial derivatives at the points are computed using the U sensitivity kernels for Vp and Vs, with Vs related to Vp and Vp/Vs perturbations. Thus, the U observations are included along with the travel-time observations in a joint inversion to best fit the data and the existing tomography model. The resulting model favors the U where there is little travel-time resolution. The combined inversion used 2949 U observations at 6-16 s period and LET from 1509 earthquakes that extend to 370 km depth, and improved the model fit by reducing the U residual data variance by 62% and the LET by 9%. The resulting model generally has better constrained depth of shallow anomalies, with decreased velocity in the upper 2 km in the western North Island, and slight focusing of crustal high velocity features at 8 km depth. Significantly, the increased resolution in the shallowest 5 km of the model improves the utility of the 3-D model for use in seismic hazard assessment, wave propagation studies, and studies comparing seismic velocities to geological mapping.

  15. A 14-year dataset of in situ glacier surface velocities for a tidewater and a land-terminating glacier in Livingston Island, Antarctica

    Science.gov (United States)

    Machío, Francisco; Rodríguez-Cielos, Ricardo; Navarro, Francisco; Lapazaran, Javier; Otero, Jaime

    2017-10-01

    We present a 14-year record of in situ glacier surface velocities determined by repeated global navigation satellite system (GNSS) measurements in a dense network of 52 stakes distributed across two glaciers, Johnsons (tidewater) and Hurd (land-terminating), located on Livingston Island, South Shetland Islands, Antarctica. The measurements cover the time period 2000-2013 and were collected at the beginning and end of each austral summer season. A second-degree polynomial approximation is fitted to each stake position, which allows estimating the approximate positions and associated velocities at intermediate times. This dataset is useful as input data for numerical models of glacier dynamics or for the calibration and validation of remotely sensed velocities for a region where very scarce in situ glacier surface velocity measurements have been available so far. The link to the data repository is as follows: http://doi.pangaea.de/10.1594/PANGAEA.846791" target="_blank">http://doi.pangaea.de/10.1594/PANGAEA.846791.

  16. Improving constraints on the growth rate of structure by modelling the density-velocity cross-correlation in the 6dF Galaxy Survey

    Science.gov (United States)

    Adams, Caitlin; Blake, Chris

    2017-10-01

    We present the first simultaneous analysis of the galaxy overdensity and peculiar velocity fields by modelling their cross-covariance. We apply our new maximum-likelihood approach to data from the 6-degree Field Galaxy Survey (6dFGS), which has the largest single collection of peculiar velocities to date. We present a full derivation of the analytic expression for the cross-covariance between the galaxy overdensity and peculiar velocity fields and find direct evidence for a non-zero correlation between the fields on scales up to ∼50 h-1 Mpc. When utilizing the cross-covariance, our measurement of the normalized growth rate of structure is fσ _8(z=0) = 0.424^{+0.067}_{-0.064} (15 per cent precision), and our measurement of the redshift-space distortion parameter is β =0.341^{+0.062}_{-0.058} (18 per cent precision). Both measurements improve by ∼20 per cent compared to only using the autocovariance information. This is consistent with the literature on multiple-tracer approaches, as well as Fisher matrix forecasts and previous analyses of 6dFGS. Our measurement of fσ8 is consistent with the standard cosmological model, and we discuss how our approach can be extended to test alternative models of gravity.

  17. Upper mantle compositional variations and discontinuity topography imaged beneath Australia from Bayesian inversion of surface-wave phase velocities and thermochemical modeling

    DEFF Research Database (Denmark)

    Khan, A.; Zunino, Andrea; Deschamps, F.

    2013-01-01

    Here we discuss the nature of velocity heterogeneities seen in seismic tomography images of Earth's mantle whose origins and relation to thermochemical variations are yet to be understood. We illustrate this by inverting fundamental-mode and higher-order surface-wave phase velocities for radial...... inference approach whereby robust uncertainty estimates are obtained. We find that both compositional and thermal anomalies are required if observations are to be satisfied. Mantle thermochemical variations extend to 250 km depth beneath western and central Australia and are characterized by increased Mg....../Fe and Mg/Si values relative to surrounding mantle. Correlated herewith are thermal variations that closely follow surface tectonics. We also observe a strong contribution to lateral variations in structure and topography across the “410 km” seismic discontinuity from thermochemically induced phase...

  18. The SDSS-III DR12 MARVELS radial velocity data release: the first data release from the multiple object Doppler exoplanet survey

    Science.gov (United States)

    Ge, Jian; Thomas, Neil B.; Li, Rui; Senan Seieroe Grieves, Nolan; Ma, Bo; de Lee, Nathan M.; Lee, Brian C.; Liu, Jian; Bolton, Adam S.; Thakar, Aniruddha R.; Weaver, Benjamin; SDSS-Iii Marvels Team

    2015-01-01

    We present the first data release from the SDSS-III Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) through the SDSS-III DR12. The data include 181,198 radial velocity (RV) measurements for a total of 5520 different FGK stars with V~7.6-12, of which more than 80% are dwarfs and subdwarfs while remainders are GK giants, among a total of 92 fields nearly randomly spread out over the entire northern sky taken with a 60-object MARVELS dispersed fixed-delay interferometer instrument over four years (2008-2012). There were 55 fields with a total of 3300 FGK stars which had 14 or more observations over about 2-year survey window. The median number of observations for these plates is 27 RV measurements. This represents the largest homogeneous sample of precision RV measurements of relatively bright stars. In this first released data, a total of 18 giant planet candidates, 16 brown dwarfs, and over 500 binaries with additional 96 targets having RV variability indicative of a giant planet companion are reported. The released data were produced by the MARVELS finalized 1D pipeline. We will also report preliminary statistical results from the MARVELS 2D data pipeline which has produced a median RV precision of ~30 m/s for stable stars.

  19. Mitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration with a reference datum

    KAUST Repository

    Sinha, Mrinal

    2016-05-23

    Imaging seismic data with an erroneous migration velocity can lead to defocused migration images. To mitigate this problem, we first choose a reference reflector whose topography is well-known from the well logs, for example. Reflections from this reference layer are correlated with the traces associated with reflections from deeper interfaces to get crosscorrelograms. Interferometric least-squares migration (ILSM) is then used to get the migration image that maximizes the crosscorrelation between the observed and the predicted crosscorrelograms. Deeper reference reflectors are used to image deeper parts of the subsurface with a greater accuracy. Results on synthetic and field data show that defocusing caused by velocity errors is largely suppressed by ILSM. We have also determined that ILSM can be used for 4D surveys in which environmental conditions and acquisition parameters are significantly different from one survey to the next. The limitations of ILSM are that it requires prior knowledge of a reference reflector in the subsurface and the velocity model below the reference reflector should be accurate.

  20. Evidence for the Kinematic Sunyaev-Zel'dovich Effect with the Atacama Cosmology Telescope and Velocity Reconstruction from the Baryon Oscillation Spectroscopic Survey

    Science.gov (United States)

    Schaan, Emmanuel S.; Ferraro, Simone; Vargas-Magana, Mariana; Smith, Kendrick M.; Ho, Shirley; Aiola, Simone; Battaglia, Nicholas; Bond, J. Richard; De Bernardis, Francesco; Calabrese, Erminia; hide

    2016-01-01

    We use microwave temperature maps from two seasons of data from the Atacama Cosmology Telescope at 146 GHz, together with the "Constant Mass" CMASS galaxy sample from the Baryon Oscillation Spectroscopic Survey to measure the kinematic Sunyaev-Zel'dovich (kSZ) effect over the redshift range z1/4 0.4-0.7. We use galaxy positions and the continuity equation to obtain a reconstruction of the line-of-sight velocity field. We stack the microwave temperature at the location of each halo, weighted by the corresponding reconstructed velocity. We vary the size of the aperture photometry filter used, thus probing the free electron profile of these halos from within the virial radius out to three virial radii, on the scales relevant for investigating the missing baryons problem. The resulting best fit kSZ model is preferred over the no-kSZ hypothesis at 3.3 and 2.9 sigma for two independent velocity reconstruction methods, using 25,537 galaxies over 660 square degrees. The data suggest that the baryon profile is shallower than the dark matter in the inner regions of the halos probed here, potentially due to energy injection from active galactic nucleus or supernovae. Thus, by constraining the gas profile on a wide range of scales, this technique will be useful for understanding the role of feedback in galaxy groups and clusters. The effect of foregrounds that are uncorrelated with the galaxy velocities is expected to be well below our signal, and residual thermal Sunyaev-Zel'dovich contamination is controlled by masking the most massive clusters. Finally, we discuss the systematics involved in converting our measurement of the kSZ amplitude into the mean free electron fraction of the halos in our sample.

  1. Spectroscopic survey of the Galaxy with Gaia - II. The expected science yield from the Radial Velocity Spectrometer

    NARCIS (Netherlands)

    Wilkinson, MI; Vallenari, A; Turon, C; Munari, U; Katz, D; Bono, G; Cropper, M; Helmi, A; Robichon, N; Thevenin, F; Vidrih, S; Zwitter, T; Arenou, F; Baylac, MO; Bertelli, G; Bijaoui, A; Boschi, F; Castelli, F; Crifo, F; David, M; Gomboc, A; Gomez, A; Haywood, M; Jauregi, U; de Laverny, P; Lebreton, Y; Marrese, P; Marsh, T; Mignot, S; Morin, D; Pasetto, S; Perryman, M; Prsa, A; Recio-Blanco, A; Royer, F; Sellier, A; Siviero, A; Sordo, R; Soubiran, C; Tomasella, L; Viala, Y

    2005-01-01

    The Gaia mission is designed as a Galaxy explorer, and will measure simultaneously, in a survey mode, the five or six phase-space parameters of all stars brighter than 20th magnitude, as well as providing a description of their astrophysical characteristics. These measurements are obtained by

  2. GIS Technique Applied To Surface Water Survey In South Western ...

    African Journals Online (AJOL)

    A GIS is used to study the surface water in Ibadan. Data which relates to the physical parameters of the study area, were used in this study. These included a SPOT-multispectral imagery, topographic and geological maps of Ibadan, which were analyzed and interpreted. The enhancement of the digital image (SPOT- ...

  3. Escape Velocity

    Directory of Open Access Journals (Sweden)

    Nikola Vlacic

    2010-01-01

    Full Text Available In this project, we investigated if it is feasible for a single staged rocket with constant thrust to attain escape velocity. We derived an equation for the velocity and position of a single staged rocket that launches vertically. From this equation, we determined if an ideal model of a rocket is able to reach escape velocity.

  4. Biological variables for the site survey of surface ecosystems - existing data and survey methods

    Energy Technology Data Exchange (ETDEWEB)

    Kylaekorpi, Lasse; Berggren, Jens; Larsson, Mats; Liberg, Maria; Rydgren, Bernt [SwedPower AB, Stockholm (Sweden)

    2000-06-01

    In the process of selecting a safe and environmentally acceptable location for the deep level repository of nuclear waste, site surveys will be carried out. These site surveys will also include studies of the biota at the site, in order to assure that the chosen site will not conflict with important ecological interests, and to establish a thorough baseline for future impact assessments and monitoring programmes. As a preparation to the site survey programme, a review of the variables that need to be surveyed is conducted. This report contains the review for some of those variables. For each variable, existing data sources and their characteristics are listed. For those variables for which existing data sources are inadequate, suggestions are made for appropriate methods that will enable the establishment of an acceptable baseline. In this report the following variables are reviewed: Fishery, Landscape, Vegetation types, Key biotopes, Species (flora and fauna), Red-listed species (flora and fauna), Biomass (flora and fauna), Water level, water retention time (incl. water body and flow), Nutrients/toxins, Oxygen concentration, Layering, stratification, Light conditions/transparency, Temperature, Sediment transport, (Marine environments are excluded from this review). For a major part of the variables, the existing data coverage is most likely insufficient. Both the temporal and/or the geographical resolution is often limited, which means that complementary surveys must be performed during (or before) the site surveys. It is, however, in general difficult to make exact judgements on the extent of existing data, and also to give suggestions for relevant methods to use in the site surveys. This can be finally decided only when the locations for the sites are decided upon. The relevance of the different variables also depends on the environmental characteristics of the sites. Therefore, we suggest that when the survey sites are selected, an additional review is

  5. Study the velocity and pressure exerted in front of the filter surface in the kitchen hood system by using ANSYS

    Science.gov (United States)

    Asmuin, Norzelawati; Pairan, M. Rasidi; Isa, Norasikin Mat; Sies, Farid

    2017-04-01

    Commercial kitchen hood ventilation system is a device used to capture and filtered the plumes from cooking activities in the kitchen area. Nowadays, it is very popular in the industrial sector such as restaurant and hotel to provide hygiene food. This study focused at the KSA filter part which installed in the kitchen hood system, the purpose of this study is to identify the critical region which indicated by observing the velocity and pressure of plumes exerted at of KSA filter. It is important to know the critical location of the KSA filter in order to install the nozzle which will helps increase the filtration effectiveness. The ANSYS 16.1 (FLUENT) software as a tool used to simulate the kitchen hood systems which consist of KSA filter. The commercial kitchen hood system model has a dimension 700 mm width, 1600 mm length and 555 mm height. The system has two inlets and one outlet. The velocity of the plumes is set to be 0.235m/s and the velocity of the inlet capture jet is set to be 1.078m/s. The KSA filter is placed 45 degree from the y axis. The result shows the plumes has more tendency flowing pass through at the bottom part of KSA filter.

  6. A Survey of Ballistic Transfers to the Lunar Surface

    Science.gov (United States)

    Anderson, Rodney L.; Parker, Jeffrey S.

    2011-01-01

    In this study techniques are developed which allow an analysis of a range of different types of transfer trajectories from the Earth to the lunar surface. Trajectories ranging from those obtained using the invariant manifolds of unstable orbits to those derived from collision orbits are analyzed. These techniques allow the computation of trajectories encompassing low-energy trajectories as well as more direct transfers. The range of possible trajectory options is summarized, and a broad range of trajectories that exist as a result of the Sun's influence are computed and analyzed. The results are then classified by type, and trades between different measures of cost are discussed.

  7. Role of Slip Velocity in a Magneto-Micropolar Fluid Flow from a Radiative Surface with Variable Permeability: A Numerical Study

    Directory of Open Access Journals (Sweden)

    Sharma B.K.

    2017-08-01

    Full Text Available An analysis is presented to describe the hydromagnetic mixed convection flow of an electrically conducting micropolar fluid past a vertical plate through a porous medium with radiation and slip flow regime. A uniform magnetic field has been considered in the study which absorbs the micropolar fluid with a varying suction velocity and acts perpendicular to the porous surface of the above plate. The governing non-linear partial differential equations have been transformed into linear partial differential equations, which are solved numerically by applying the explicit finite difference method. The numerical results are presented graphically in the form of velocity, micro-rotation, concentration and temperature profiles, the skin-friction coefficient, the couple stress coefficient, the rate of heat and mass transfers at the wall for different material parameters.

  8. Global Properties of M31’s Stellar Halo from the SPLASH Survey. III. Measuring the Stellar Velocity Dispersion Profile

    Science.gov (United States)

    Gilbert, Karoline M.; Tollerud, Erik; Beaton, Rachael L.; Guhathakurta, Puragra; Bullock, James S.; Chiba, Masashi; Kalirai, Jason S.; Kirby, Evan N.; Majewski, Steven R.; Tanaka, Mikito

    2018-01-01

    We present the velocity dispersion of red giant branch stars in M31’s halo, derived by modeling the line-of-sight velocity distribution of over 5000 stars in 50 fields spread throughout M31’s stellar halo. The data set was obtained as part of the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH) Survey, and covers projected radii of 9 to 175 kpc from M31’s center. All major structural components along the line of sight in both the Milky Way (MW) and M31 are incorporated in a Gaussian Mixture Model, including all previously identified M31 tidal debris features in the observed fields. The probability that an individual star is a constituent of M31 or the MW, based on a set of empirical photometric and spectroscopic diagnostics, is included as a prior probability in the mixture model. The velocity dispersion of stars in M31’s halo is found to decrease only mildly with projected radius, from 108 km s‑1 in the innermost radial bin (8.2 to 14.1 kpc) to ∼80 to 90 km s‑1 at projected radii of ∼40–130 kpc, and can be parameterized with a power law of slope ‑0.12 ± 0.05. The quoted uncertainty on the power-law slope reflects only the precision of the method, although other sources of uncertainty we consider contribute negligibly to the overall error budget. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  9. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during October 2015 (NCEI Accession 0138228)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  10. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during September 2015 (NCEI Accession 0137285)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  11. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during July 2016 (NCEI Accession 0156399)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  12. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during July 2015 (NCEI Accession 0131976)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  13. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during November 2015 (NCEI Accession 0139551)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  14. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during August 2015 (NCEI Accession 0131989)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  15. Near-real-time surface ocean velocities derived from HF radar stations located along coastal waters of North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico, Hawaii and western US during August 2016 (NCEI Accession 0156623)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains near-real-time ocean surface velocities, also known as total vector velocities, derived from HF radar stations. The velocities are...

  16. Velocity and Strain Rate Fields in Eastern Marmara Region Inferred from a Combination of Survey Mode and CORS GPS Data

    Science.gov (United States)

    Ozener, H.; Garagon Dogru, A.; Aktug, B.; Ergintav, S.; Yilmaz, O.; Turgut, B.; Halicioglu, K.; Sabuncu, A.; Havazli, E.; Gurkan, O.; Reilinger, R. E.

    2013-12-01

    North Anatolian Fault System (NAFS) is a well-known transform boundary between the Eurasian and Anatolian plates. The western part of the fault has a remarkable history of seismic activity and quantification of the deformation is needed especially for the northern strand, which consists of Izmit segment, Prince's Islands segment, and Ganos segment. Space geodetic data provide valuable information to constrain the seismic potential of the area. The Geodesy Department of Kandilli Observatory and Earthquake Research Institute at Bogazici University has conducted GPS surveys since 1994 on near-fault geodetic networks. Annually surveyed GPS data from 24 stations of 3 geodetic networks and continuous data from permanent stations are combined to study both the spatial and the temporal variations of crustal strain in the area. These small-aperture geodetic networks include three different sites and were deployed across the North Anatolian Fault System in 1990. Both trilateration and triangulation measurements along with GPS observations were carried out periodically. These measurements allow us to characterize the deformation and fault kinematics near the fault, and they also provide the opportunity to quantify the co-seismic and post-seismic deformation of the 1999 Izmit Earthquake along the coseismic fault break. The continuous GPS measurements are well suited to detect aseismic strain transients and the small-aperture geodetic networks are useful for monitoring systematic variations in the near-fault strain rate (creep events). The geodetic observations from these observations, covering the period 1994-2013 will be presented and used to investigate the mechanism of these transient strain events and their relationship to earthquake activity.

  17. An HST Survey of Cassiopeia A's Reverse Shock, High-Velocity Ejecta, and Shocked Clouds of Pre-SN Mass Loss

    Science.gov (United States)

    Fesen, Robert

    2017-08-01

    The young Galactic supernova remnant Cassiopeia A (Cas A) provides us with the clearest look at the properties and explosion dynamics of a high mass, core-collapse supernova (CCSN). With an explosion date around 1670, Cas A is the youngest Galactic core-collapse SNR known and, at an estimated distance of 3.4 kpc, it is also among the closest. Cas A's main shell ejecta knots are typically 0.1 - 0.5 arcsec in size and can show emission and morphological changes on timescales of just a few months. No other remnant, with the exception of SN 1987A, shows such rapid optical changes across large portions of its structure.Here we propose a new, complete optical survey of Cas A, the first since 2004, in order to measure the velocity and asymmetry of Cas A's reverse shock front across the whole remnant and map the distribution of its high-velocity outer ejecta, particularly in regions which align to the motion of the central compact source. Halpha images of the remnant's shocked CSM clumps will also provide strong tests of shock-cloud models across a broad range of cloud densities and sizes. These data will constitute a rich and unique archive both for Cas A and the general study of high mass CCSNe.

  18. An integrated geophysical survey of Kilbourne Hole, southern New Mexico: Implications for near surface exploration of Mars and the Moon

    Science.gov (United States)

    Maksim, Nisa

    zone, and the initial gas expansion velocity) are used to quantitatively calculate the mass, volume and condition of groundwater involved in the magma-water interaction process that caused Kilbourne Hole eruption. The joint gravity and magnetic 2D inversion reveals two main bodies of basaltic intrusion dike underneath Kilbourne Hole. The depth to the top of the dike is varied between 0.91 and 3.58 km from the ground surface. The models are able to delineate several complex areas of slumping blocks and collapsed crater, the area of the diatreme and the area of the original crater's excavation. The estimated depth of the diatreme is 13.6-15.8 km. The model shows that the tuff ring deposits extend 600 m to 1 km away from the crater rim and vary in thickness (50-150 m). Based on our 2D gravity and magnetic inverse models of Kilbourne Hole, we were able to calculate the mass of the magma and the final product of this research, which is the mass of water that fed the Kilbourne Hole eruption. The total mass of the magma (M m) is 1.38 +/- 0.15 x 1013 kg and the mass of water (Mw) is (1.09 +/- 0.31) x 10 13 kg. The water to rock mass ratio of the Kilbourne Hole eruption was 0.01-0-02. With the GPR surveys results, we estimate that the initial gas expansion velocity (V0) of the Kilbourne Hole eruption was 123 +/- 9 m/s and the time duration of the gas expansion phase was 92 +/- 11 s. The obtained initial gas expansion velocity and the depth of the dikes suggest that the eruption occurred at an initial pressure of 163 +/- 9 bar. I also utilized the lunar gravity field measured by the Gravity Recovery and Interior Laboratory (GRAIL) mission to reconstruct the history of lunar mascon basin formation and magmatic activity. We hypothesize that a combination of uplifted lunar Moho, impact melt sheets, and brecciated crust creates the gravity signature of lunar mascon basins. To test this hypothesis, We performed low-pass and preferential filtering on the free-air anomaly map derived

  19. Accurate Determination of Glacier Surface Velocity Fields with a DEM-Assisted Pixel-Tracking Technique from SAR Imagery

    Directory of Open Access Journals (Sweden)

    Shiyong Yan

    2015-08-01

    Full Text Available We obtained accurate, detailed motion distribution of glaciers in Central Asia by applying digital elevation model (DEM assisted pixel-tracking method to L-band synthetic aperture radar imagery. The paper firstly introduces and analyzes each component of the offset field briefly, and then describes the method used to efficiently and precisely compensate the topography-related offset caused by the large spatial baseline and rugged terrain with the help of DEM. The results indicate that the rugged topography not only forms the complex shapes of glaciers, but also affects the glacier velocity estimation, especially with large spatial baseline. The maximum velocity, 0.85 m∙d−1, was observed in the middle part on the Fedchenko Glacier, which is the world’s longest mountain glacier. The motion fluctuation on its main trunk is apparently influenced by mass flowing in from tributaries, as well as angles between tributaries and the main stream. The approach presented in this paper was proved to be highly appropriate for monitoring glacier motion and will provide valuable sensitive indicators of current and future climate change for environmental analysis.

  20. High coupling and high velocity surface acoustic waves using a c-axis oriented ZnO film on translucent Al2O3 ceramics

    Science.gov (United States)

    Takeda, Fumio; Shiosaki, Tadashi; Kawabata, Akira

    1983-07-01

    The layered structure comprising a c-axis normally oriented ZnO piezoelectric film and a translucent Al2O3 ceramic substrate which has a high surface-acoustic-wave velocity and a small surface roughness has given both a high phase velocity Vp and a high coupling k2 for the 0th (Rayleigh) mode, 1st (Sezawa) mode, and leaky mode surface acoustic waves. The measured maximum values of k2 are 3.6% for the 0th mode at h/λ=0.45 where Vp is 3.2 km/s, 5.7% for the 1st mode at h/λ=0.21 where Vp is 5.6 km/s, and 6.7% for the leaky mode at h/λ=0.16 where Vp is 6.2 km/s, where the interdigital transducers are located at the interface in measuring the above values, and also electrically floating plane metals are on top of the ZnO film for the last two values.

  1. Surface stress, initial stress and Knudsen-dependent flow velocity effects on the electro-thermo nonlocal wave propagation of SWBNNTs

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbanpour Arani, A., E-mail: aghorban@kashanu.ac.ir [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of); Roudbari, M.A. [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of)

    2014-11-01

    This paper investigates the electro-thermal nonlocal wave propagation of fluid-conveying single-walled Boron Nitride nanotubes (SWBNNTs) using nonlocal piezoelasticity with surface stress, initial stress and Knudsen-dependent flow velocity effect. SWBNNT is embedded in a vicsoelastic medium which is simulated as visco-Pasternak foundation. Using Euler–Bernoulli beam (EBB) model, Hamilton's principle and nonlocal piezoelasticity theory, the higher order governing equation is derived. A detailed parametric study is conducted, focusing on the combined effects of the electric parameters, viscoelastic medium, initial stress, surface stress, Knudsen number (Kn) and small scale on the wave propagation behaviour of the fluid-conveying SWBNNT. The results show that for smaller values of wave number the dispersion relation for different fluid viscosities seems to be similar. At the higher values of wave numbers, increase in the wave frequency values is remarkable due to increase in fluid viscosity. The electric field as a smart controller, surface effect, initial stress, temperature change and slip velocity effect have significant role on the wave frequency. The results of this work is hoped to be of use in design and manufacturing of smart MEMS/NEMS in advanced medical applications such as drug delivery systems with great applications in biomechanics.

  2. Seasonal and interannual variabilities in terminus position, glacier velocity, and surface elevation at Helheim and Kangerlussuaq Glaciers from 2008 to 2016

    Science.gov (United States)

    Kehrl, L. M.; Joughin, I.; Shean, D. E.; Floricioiu, D.; Krieger, L.

    2017-09-01

    The dynamic response of Greenland tidewater glaciers to oceanic and atmospheric change has varied both spatially and temporally. While some of this variability is likely related to regional climate signals, glacier geometry also appears to be important. In this study, we investigated the environmental and geometric controls on the seasonal and interannual evolution of Helheim and Kangerlussuaq Glaciers, Southeast Greenland, from 2008 to 2016, by combining year-round, satellite measurements of terminus position, glacier velocity, and surface elevation. While Helheim remained relatively stable with a lightly grounded terminus over this time period, Kangerlussuaq continued to lose mass as its grounding line retreated into deeper water. By summer 2011, Kangerlussuaq's grounding line had retreated into shallower water, and the glacier had an 5 km long floating ice tongue. We also observed seasonal variations in surface velocity and elevation at both glaciers. At Helheim, seasonal speedups and dynamic thinning occurred in the late summer when the terminus was most retreated. At Kangerlussuaq, we observed summer speedups due to surface-melt-induced basal lubrication and winter speedups due to ice-shelf retreat. We suggest that Helheim and Kangerlussuaq behaved differently on a seasonal timescale due to differences in the spatial extent of floating ice near their termini, which affected iceberg-calving behavior. Given that seasonal speedups and dynamic thinning can alter this spatial extent, these variations may be important for understanding the long-term evolution of these and other Greenland tidewater glaciers.

  3. An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group

    Science.gov (United States)

    Richter, P.; Nuza, S. E.; Fox, A. J.; Wakker, B. P.; Lehner, N.; Ben Bekhti, N.; Fechner, C.; Wendt, M.; Howk, J. C.; Muzahid, S.; Ganguly, R.; Charlton, J. C.

    2017-11-01

    Context. The Milky Way is surrounded by large amounts of diffuse gaseous matter that connects the stellar body of our Galaxy with its large-scale Local Group (LG) environment. Aims: To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV) spectra of extragalactic background sources. The UV data are obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and are supplemented by 21 cm radio observations of neutral hydrogen. Methods: Along 270 sightlines we measure metal absorption in the lines of Si II, Si III, C II, and C iv and associated H I 21 cm emission in HVCs in the velocity range | vLSR | = 100-500 km s-1. With this unprecedented large HVC sample we were able to improve the statistics on HVC covering fractions, ionization conditions, small-scale structure, CGM mass, and inflow rate. For the first time, we determine robustly the angular two point correlation function of the high-velocity absorbers, systematically analyze antipodal sightlines on the celestial sphere, and compare the HVC absorption characteristics with that of damped Lyman α absorbers (DLAs) and constrained cosmological simulations of the LG (CLUES project). Results: The overall sky-covering fraction of high-velocity absorption is 77 ± 6 percent for the most sensitive ion in our survey, Si III, and for column densities log N(Si III)≥ 12.1. This value is 4-5 times higher than the covering fraction of 21 cm neutral hydrogen emission at log N(H I)≥ 18.7 along the same lines of sight, demonstrating that the Milky Way's CGM is multi-phase and predominantly ionized. The measured equivalent-width ratios of Si II, Si III, C II, and C iv are inhomogeneously distributed on large and small angular scales, suggesting a complex spatial distribution of multi-phase gas that surrounds the

  4. Combining High-Contrast Imaging with Doppler Radial Velocity: a Survey of Subgiant Stars that Exhibit Long-term Linear Trends

    Science.gov (United States)

    Crepp, Justin R.; Johnson, J. A.

    2010-01-01

    We are commencing a high-contrast imaging survey at Keck that will target several dozen nearby subgiant stars that show evidence for the existence of a distant companion, as is indicated by a long-term, linear radial velocity (RV) trend. The goal of the survey is to place very tight constraints on the mass and orbit of the body responsible for accelerating each star. Our targets are massive, former A-stars and 28% have a known exoplanet. The typical time baseline for Doppler measurements is 3+ years and a number of targets have minimum periods of 12 years. By combining complementary detection techniques, we will be able to determine with high statistical confidence whether the (outer-most) companion is stellar or substellar in nature for most of the sample. This "inside-out" approach will provide a measure of the occurrence rate of multi-planet systems and brown dwarfs around massive stars. In this poster, we present further motivation on the topic, including several representative RV curves and the anticipated mass, inclination, and semi-major axis constraints imposed by imaging and RV.

  5. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during December 2015 (NCEI Accession 0141107)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  6. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during July 2016 (NCEI Accession 0156405)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  7. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during November 2015 (NCEI Accession 0139553)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  8. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during May 2016 (NCEI Accession 0154390)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  9. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during June 2016 (NCEI Accession 0155984)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  10. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during May 2015 (NCEI Accession 0138488)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  11. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during January 2016 (NCEI Accession 0144289)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  12. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during February 2016 (NCEI Accession 0145802)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  13. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during June 2015 (NCEI Accession 0138584)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  14. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during September 2015 (NCEI Accession 0138948)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  15. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during August 2016 (NCEI Accession 0156626)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  16. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during April 2016 (NCEI Accession 0151734)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  17. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during October 2015 (NCEI Accession 0139156)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  18. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during July 2015 (NCEI Accession 0138671)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  19. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during February 2015 (NCEI Accession 0137265)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  20. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during April 2015 (NCEI Accession 0138389)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  1. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during January 2015 (NCEI Accession 0137088)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  2. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during March 2015 (NCEI Accession 0138305)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  3. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during March 2016 (NCEI Accession 0148080)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  4. Surface ocean velocities obtained by HF radar from stations located along coastal waters of Antarctica, Hawaii, North Slope Alaska, Puerto Rico/Virgin Islands, eastern US/Gulf of Mexico and western US during August 2015 (NCEI Accession 0138776)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The archival package contains ocean surface radial velocities collected from High frequency (HF) radar stations. NDBC, which with SIO assembles data from the IOOS HF...

  5. Dependence of the Photocurrent of a Schottky-Barrier Solar Cell on the Back Surface Recombination Velocity and Suggestion for a Structure with Improved Performance

    Directory of Open Access Journals (Sweden)

    Avigyan Chatterjee

    2015-01-01

    Full Text Available Though Schottky-barrier solar cells have been studied extensively previously, not much work has been done recently on these cells, because of the fact that conventional p-n junction silicon solar cells have much higher efficiency and have attracted the attention of most of the researchers. However, the Schottky-barrier solar cells have the advantage of simple and economical fabrication process. In this paper, the effect of back surface recombination velocity on the minority carrier distribution and the spectral response of a Schottky-barrier silicon solar cell have been investigated and, based on this study, a new design of the cell with a back surface field has been suggested, which is expected to give much improved performance.

  6. An analytical expression for ion velocities at the wall including the sheath electric field and surface biasing for erosion modeling at JET ILW

    Directory of Open Access Journals (Sweden)

    I. Borodkina

    2017-08-01

    Full Text Available For simulation of plasma-facing component erosion in fusion experiments, an analytical expression for the ion velocity just before the surface impact including the local electric field and an optional surface biasing effect is suggested. Energy and angular impact distributions and the resulting effective sputtering yields were produced for several experimental scenarios at JET ILW mostly involving PFCs exposed to an oblique magnetic field. The analytic solution has been applied as an improvement to earlier ERO modelling of localized, Be outer limiter, RF-enhanced erosion, modulated by toggling of a remote, however magnetically connected ICRH antenna. The effective W sputtering yields due to D and Be ion impact in Type-I and Type-III ELMs and inter-ELM conditions were also estimated using the analytical approach and benchmarked by spectroscopy. The intra-ELM W sputtering flux increases almost 10 times in comparison to the inter-ELM flux.

  7. Semi-automatic surface sediment sampling system - A prototype to be implemented in bivalve fishing surveys

    Science.gov (United States)

    Rufino, Marta M.; Baptista, Paulo; Pereira, Fábio; Gaspar, Miguel B.

    2018-01-01

    In the current work we propose a new method to sample surface sediment during bivalve fishing surveys. Fishing institutes all around the word carry out regular surveys with the aim of monitoring the stocks of commercial species. These surveys comprise often more than one hundred of sampling stations and cover large geographical areas. Although superficial sediment grain sizes are among the main drivers of benthic communities and provide crucial information for studies on coastal dynamics, overall there is a strong lack of this type of data, possibly, because traditional surface sediment sampling methods use grabs, that require considerable time and effort to be carried out on regular basis or on large areas. In face of these aspects, we developed an easy and un-expensive method to sample superficial sediments, during bivalve fisheries monitoring surveys, without increasing survey time or human resources. The method was successfully evaluated and validated during a typical bivalve survey carried out on the Northwest coast of Portugal, confirming that it had any interference with the survey objectives. Furthermore, the method was validated by collecting samples using a traditional Van Veen grabs (traditional method), which showed a similar grain size composition to the ones collected by the new method, on the same localities. We recommend that the procedure is implemented on regular bivalve fishing surveys, together with an image analysis system to analyse the collected samples. The new method will provide substantial quantity of data on surface sediment in coastal areas, using a non-expensive and efficient manner, with a high potential application in different fields of research.

  8. Surface deformation before, during and after the 2014 South Napa, California, earthquake from a spatially dense network of survey and continuous GPS site

    Science.gov (United States)

    Floyd, M.; Funning, G.; Murray, J. R.; Svarc, J. L.; Herring, T.; Johanson, I. A.; Swiatlowski, J.; Materna, K.; Johnson, C. W.; Boyd, O. S.; Sutton, J. M.; Phillips, E.

    2014-12-01

    The South Napa, California, earthquake occurred on the West Napa Fault within a dense network of established GPS sites. Continuous sites from the Plate Boundary Observatory (PBO), Bay Area Regional Deformation (BARD) and other publicly-available networks lie mostly in the far-field, greater than 15 km from the epicenter. The near-field is covered by two networks of survey GPS sites, one observed by the University of California, Riverside (UCR) and MIT, and the other by the US Geological Survey (USGS). First, we present the pre-earthquake GPS velocity solution from the combination of these networks, covering the entire Pacific-North America plate boundary zone north of San Francisco Bay. We take 1-D fault-perpendicular profile and block model approaches to fit the GPS velocities, both with and without an explicit West Napa Fault, to update previous estimates of slip rates on faults to the east of the Rodgers Creek Fault, which include the West Napa and Green Valley Faults. Second, we present results from the survey GPS field response to the South Napa earthquake. 13 survey sites within 20 km of the epicenter were re-observed within 15 hours of the earthquake by a UCR-MIT group with assistance from UC Berkeley. An additional two sites to the north of the rupture were re-observed within 36 hours. A USGS-led group re-observed 17 sites within 25 km of the epicenter, as well as sites further afield. In total, 35 survey-mode GPS instruments were deployed to observe post-earthquake motions for up to four weeks after the event. Maximum displacements of greater than 20 cm are observed at two survey GPS sites within 2 km and either side of the surface rupture, in agreement with visual inspection of surface rupture offsets. Other observed survey sites within 20 km show at least 2 cm of displacement and 22 continuous GPS sites show displacements that are statistically significant at the 2-sigma level. Further, we show post-earthquake displacements over time as a result of this

  9. Literature Survey Concerning State of the Art and Surface Generation in High Speed Milling

    DEFF Research Database (Denmark)

    Bissacco, Giuliano

    This report constitutes a short description of a literature survey concerning the state of the art and latest achievements on the rather new and powerful technology of high speed milling and its modelling, particularly looking at modelling of the generated surfaces. This task has been conducted...

  10. Analysis of method of polarization surveying of water surface oil pollution

    Science.gov (United States)

    Zhukov, B. S.

    1979-01-01

    A method of polarization surveying of oil films on the water surface is analyzed. Model calculations of contrasted oil and water obtained with different orientations of the analyzer are discussed. The model depends on the spectral range, water transparency and oil film, and the selection of observational direction.

  11. The impact of surface-wave separation on seismic survey design

    NARCIS (Netherlands)

    Ishiyama, T.; Blacquiere, G.; Mulder, W.A.

    2015-01-01

    3-D seismic survey design provides an acquisition geometry for obtaining seismic data that enable imaging and amplitude-versus-offset applications of target reflectors with sufficient quality under given economical and operational constraints. However, in land or shallow water environments, surface

  12. Near-surface 3D reflections seismic survey; Sanjigen senso hanshaho jishin tansa

    Energy Technology Data Exchange (ETDEWEB)

    Nakahigashi, H.; Mitsui, H.; Nakano, O.; Kobayashi, T. [DIA Consultants Co. Ltd., Tokyo (Japan)

    1997-05-27

    Faults are being actively investigated across Japan since the Great Hanshin-Awaji Earthquake. Discussed in this report is the application of the 3D near-surface reflection seismic survey in big cities. Data from trenching and drilling is used for the geological interpretation of the surroundings of a fault, and the reflection seismic survey is used to identify the position, etc., of the fault. In this article, when the results obtained from the experimental field are examined, it is found that the conventional 2D imaging reflection survey betrays the limit of its capability when the geological structure is complicated, that the 3D reflection seismic survey, on the contrary, is capable of high-precision imaging and, when augmented by drilling, etc., becomes capable of a more detailed interpretation, and that it also contributes effectively to the improvement of local disaster prevention in big cities. Using as the model the Tachikawa fault that runs near JR Tachikawa Station, embodiment of the 3D reflection seismic survey is reviewed. For the acquisition of data excellent in quality in a 3D reflection seismic survey conducted utilizing the roads in the sector chosen for experiment in the urban area, the shock generating points and receiving points should be positioned by taking into account the parameters in the bin arranging process so that the mid-points will be regularly distributed on the surface. 3 refs., 11 figs., 1 tab.

  13. Survey of nine surface mines in North America. [Nine different mines in USA and Canada

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, L.G.; Brackett, R.D.; Floyd, F.D.

    1981-01-01

    This report presents the information gathered by three mining engineers in a 1980 survey of nine surface mines in the United States and Canada. The mines visited included seven coal mines, one copper mine, and one tar sands mine selected as representative of present state of the art in open pit, strip, and terrace pit mining. The purpose of the survey was to investigate mining methods, equipment requirements, operating costs, reclamation procedures and costs, and other aspects of current surface mining practices in order to acquire basic data for a study comparing conventional and terrace pit mining methods, particularly in deeper overburdens. The survey was conducted as part of a project under DOE Contract No. DE-AC01-79ET10023 titled The Development of Optimal Terrace Pit Coal Mining Systems.

  14. Quantitative estimation of minimum offset for multichannel surface-wave survey with actively exciting source

    Science.gov (United States)

    Xu, Y.; Xia, J.; Miller, R.D.

    2006-01-01

    Multichannel analysis of surface waves is a developing method widely used in shallow subsurface investigations. The field procedures and related parameters are very important for successful applications. Among these parameters, the source-receiver offset range is seldom discussed in theory and normally determined by empirical or semi-quantitative methods in current practice. This paper discusses the problem from a theoretical perspective. A formula for quantitatively evaluating a layered homogenous elastic model was developed. The analytical results based on simple models and experimental data demonstrate that the formula is correct for surface wave surveys for near-surface applications. ?? 2005 Elsevier B.V. All rights reserved.

  15. Parsimonious Surface Wave Interferometry

    KAUST Repository

    Li, Jing

    2017-10-24

    To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.

  16. Meaningful use of peak particle velocities at excavation surfaces for the optimisation of the rockburst criteria for tunnels and stopes.

    CSIR Research Space (South Africa)

    Milev, AM

    2002-03-01

    Full Text Available = angular frequency ψ = potential for S-wave x = site response attenuation 1 1 Introduction 1.1 Motivation In seismic and rockburst-prone mines, sudden fault rupture or the failure of highly strained rock leads to energy being radiated in the form... of seismic waves. The seismic waves interact with mining excavations, leading to interface and surface waves, energy channelling and wave focussing. The rock is subjected to rapid accelerations, resulting in rock-fabric failure, keyblock ejection and stope...

  17. THE HIGH-VELOCITY SYSTEM: INFALL OF A GIANT LOW-SURFACE-BRIGHTNESS GALAXY TOWARD THE CENTER OF THE PERSEUS CLUSTER

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Alice P.-Y.; Lim, Jeremy; Chan, Jeffrey C.-C. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Ohyama, Youichi [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan (China); Broadhurst, T. [Department of Theoretical Physics, University of Basque Country UPV/EHU, Bilbao (Spain)

    2015-12-01

    The high-velocity system (HVS) lies just north-west of the center and is moving at a speed of 3000 km s{sup −1} toward NGC 1275, the central giant elliptical galaxy in the Perseus cluster. We report imaging spectroscopy of the HVS in Hα and [N ii] that resolves both the nature of this galaxy and its physical relationship with NGC 1275. The HVS exhibits a distorted disk having a projected rotational velocity that rises steadily to ∼200 km s{sup −1} at a radius of ∼12 kpc, the same maximal extent detectable in neutral gas and dust. We discover highly blueshifted emission at relative velocities of up to ∼800 km s{sup −1} distributed throughout and confined almost entirely within the projected area of the disk, tracing gas stripped by ram pressure. The distribution of the stripped gas implies that the HVS is moving essentially along our sightline closely toward the center of NGC 1275. We show that the speed of the HVS is consistent with it having fallen from rest at the virial radius of the Perseus cluster and reached ∼100 kpc from the cluster center. Despite having an overall metallicity (inferred from [N ii]/Hα) significantly lower than that of star-forming disk galaxies, the HVS exhibits a current star formation rate of ∼3.6 M{sub ⊙} yr{sup −1} and numerous young star clusters projected against giant H ii regions. The evidence assembled implicates a progenitor giant low-surface-brightness galaxy that, because of galaxy harassment and/or the cluster tidal field, has developed two prominent spiral arms along which star formation is strongly elevated.

  18. Joint analysis of refraction seismic survey with multilevel hydrophone measurement (application for detecting the high velocity thin lid); Kussekiho jishin tansa data to kochu hydrophone data no fukugo kaiseki no rei

    Energy Technology Data Exchange (ETDEWEB)

    Mori, S.; Harada, T.; Hayashi, K. [OYO Corp., Tokyo (Japan)

    1996-05-01

    During a refraction seismic survey conducted at a spot where a high-speed lava layer is supposedly concealed, the distribution of lava layer was estimated, and a composite analysis involving the vibration data received via hydrophones arranged in a bore hole was accomplished using a high-speed model based on an assumed geological section. The refraction survey centered on the bore hole and was accomplished using 250m-long traverse lines extending therefrom, one to the upstream and the other to the downstream of a river, producing a total length of 500m. The hydrophones were installed in the bore hole, and the measurement was carried out in an offset VSP-like observation pattern. In the analysis, the velocities obtained by the refraction survey and velocity logging were assigned to each layer on the basis of the assumed geological section for the construction of a velocity distribution model, which served as the early model for the repetition of calculation. Calculation was repeated with help of the said model, and a geological structure, capable of explaining the travel time data collected during the refraction survey and velocity logging, was successfully estimated. 1 ref., 5 figs.

  19. Impact of layer and substrate properties on the surface acoustic wave velocity in scandium doped aluminum nitride based SAW devices on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Gillinger, M., E-mail: manuel.gillinger@tuwien.ac.at; Knobloch, T.; Schneider, M.; Schmid, U. [Institute of Sensor and Actuator Systems, TU Wien, 1040 Vienna (Austria); Shaposhnikov, K.; Kaltenbacher, M. [Institute of Mechanics and Mechatronics, TU Wien, 1040 Vienna (Austria)

    2016-06-06

    This paper investigates the performance of surface acoustic wave (SAW) devices consisting of reactively sputter deposited scandium doped aluminum nitride (Sc{sub x}Al{sub 1-x}N) thin films as piezoelectric layers on sapphire substrates for wireless sensor or for RF-MEMS applications. To investigate the influence of piezoelectric film thickness on the device properties, samples with thickness ranging from 500 nm up to 3000 nm are fabricated. S{sub 21} measurements and simulations demonstrate that the phase velocity is predominantly influenced by the mass density of the electrode material rather than by the thickness of the piezoelectric film. Additionally, the wave propagation direction is varied by rotating the interdigital transducer structures with respect to the crystal orientation of the substrate. The phase velocity is about 2.5% higher for a-direction compared to m-direction of the sapphire substrate, which is in excellent agreement with the difference in the anisotropic Young's modulus of the substrate corresponding to these directions.

  20. The thermo-chemical and physical structure beneath the North American continent from Bayesian inversion of surface-wave phase velocities

    DEFF Research Database (Denmark)

    Khan, A.; Zunino, A.; Deschamps, F.

    2011-01-01

    -consistent thermodynamic method whereby phase equilibria and physical properties (P-, S-wave velocity and density) are computed as functions of composition (in the Na2O-CaO-FeO-MgO-Al2O 3-SiO2 model system), pressure and temperature. We employ a sampling-based strategy to solve the non-linear inverse problem relying......We jointly invert local fundamental-mode and higher-order surface-wave phase-velocities for radial models of the thermo-chemical and anisotropic physical structure of the Earth's mantle to ∼1000 km depth beneath the North American continent. Inversion for thermo-chemical state relies on a self...... and oceans). In the transition zone the thermo-chemical structure decouples from that of the upper mantle, with a relatively hot thermal anomaly appearing beneath the cratonic area that likely extends into the lower mantle. In the lower mantle no consistent large-scale thermo-chemical heterogeneities...

  1. Experimental study on the wall jet over a riblet surface. ; Measurement of mean and fluctuating velocities and estimation of drag reduction. Riburetto men ni sou hekimen funryu ni kansuru jikkenteki kenkyu. ; Heikin-hendo sokudoba to teiko gensho no hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, S. (Gifu Univ., Gifu (Japan). Faculty of Engineering); Hayashimoto, H. (Gifu Univ., Gifu (Japan). Graduate School); Inoue, Y. (Suzuka National College of Technology, Mie (Japan)); Iwakami, Y.

    1994-04-25

    A wall-jet has a wide range of application such as to control of the boundary layer of a wing of an aeroplane, control of temperature of the vanes of a gas turbine and flow inside a fluid control device. This field of flow comprises a wall layer on the wall side having the characteristics of a boundary layer and an outer layer on the external side which is like a free jet, the two layers being separated by a boundary where the flow is at a maximum speed. This study was carried out to clarify the effect of riblets experimentally using as a base jet a wall jet which was one of basic shearing flows. In particular, studied were the degrees of change in the mean and fluctuating velocities near the wall surface and reduction of drag. The following results were obtained. A significant difference was recognized in the vicinity of the wall in the mean velocity distribution between the mean velocities on the riblet surface and on the smooth surface. The fluctuating velocity component in the x direction on the riblet surface decreased by about a maximum of 20% when compared with that on the smooth surface. In contrast, the fluctuating velocity in the y direction and Reynolds shearing stress both on the riblet and smooth surfaces were substantially in agreement with each other within the range of this experiment. 28 refs., 12 figs., 1 tab.

  2. Using surface velocities to calculate ice thickness and bed topography: A case study at Columbia Glacier, Alaska, USA

    Science.gov (United States)

    McNabb, R.W.; Hock, R.; O'Neel, Shad; Rasmussen, Lowell A.; Ahn, Y.; Braun, M.; Conway, H.; Herreid, S.; Joughin, I.; Pfeffer, W.T.; Smith, B.E.; Truffer, M.

    2012-01-01

    Information about glacier volume and ice thickness distribution is essential for many glaciological applications, but direct measurements of ice thickness can be difficult and costly. We present a new method that calculates ice thickness via an estimate of ice flux. We solve the familiar continuity equation between adjacent flowlines, which decreases the computational time required compared to a solution on the whole grid. We test the method on Columbia Glacier, a large tidewater glacier in Alaska, USA, and compare calculated and measured ice thicknesses, with favorable results. This shows the potential of this method for estimating ice thickness distribution of glaciers for which only surface data are available. We find that both the mean thickness and volume of Columbia Glacier were approximately halved over the period 1957–2007, from 281m to 143 m, and from 294 km3 to 134 km3, respectively. Using bedrock slope and considering how waves of thickness change propagate through the glacier, we conduct a brief analysis of the instability of Columbia Glacier, which leads us to conclude that the rapid portion of the retreat may be nearing an end.

  3. MERIDL- VELOCITIES AND STREAMLINES ON THE HUB-SHROUD MIDCHANNEL STREAM SURFACE OF AN AXIAL, RADIAL, OR MIXED FLOW TURBOMACHINE OR ANNULAR DUCT

    Science.gov (United States)

    Katsanis, T.

    1994-01-01

    This computer program was developed for calculating the subsonic or transonic flow on the hub-shroud mid-channel stream surface of a single blade row of a turbomachine. The design and analysis of blades for compressors and turbines ideally requires methods for analyzing unsteady, three-dimensional, turbulent viscous flow through a turbomachine. Since an exact solution is impossible at present, solutions on two-dimensional surfaces are calculated to obtain a quasi-three dimensional solution. When three-dimensional effects are important, significant information can be obtained from a solution on a cross-sectional surface of the passage normal to the flow. With this program, a solution to the equations of flow on the meridional surface can be carried out. This solution is chosen when the turbomachine under consideration has significant variation in flow properties in the hubshroud direction, especially when input is needed for use in blade-to-blade calculations. The program can also perform flow calculations for annular ducts without blades. This program should prove very useful in the design and analysis of any turbomachine. This program calculates a solution for two-dimensional, adiabatic shockfree flow. The flow must be essentially subsonic, but there may be local areas of supersonic flow. To obtain the solution, this program uses both the finite difference and the quasi-orthogonal (velocity gradient) methods combined in a way that takes maximum advantage of both. The finite-difference method solves a finite-difference equation along the meridional stream surface in a very efficient manner but is limited to subsonic velocities. This approach must be used in cases where the blade aspect ratios are above one, cases where the passage is curved, and cases with low hub-tip-ratio blades. The quasi-orthogonal method solves the velocity gradient equation on the meridional surface and is used if it is necessary to extend the range of solutions into the transonic regime. In

  4. Orbital velocity

    OpenAIRE

    Modestino, Giuseppina

    2016-01-01

    The trajectory and the orbital velocity are determined for an object moving in a gravitational system, in terms of fundamental and independent variables. In particular, considering a path on equipotential line, the elliptical orbit is naturally traced, verifying evidently the keplerian laws. The case of the planets of the solar system is presented.

  5. Effect of surface treatments on the spreading velocity of simplified adhesive systems Efeito de tratamentos de superfície na velocidade de escoamento de sistemas adesivos simplificados

    Directory of Open Access Journals (Sweden)

    Flávia B. Pazinatto

    2006-12-01

    Full Text Available OBJECTIVES: To determine the roughness of glass surfaces submitted to different treatments and to correlate it with the spreading velocity of two adhesive systems. MATERIALS AND METHODS: Glass slides were used as substrates to evaluate the spreading velocity of Single Bond and Prime & Bond NT adhesive systems. Six different surface treatments were compared: 1 no treatment; 2 silanization (SL; 3 sandblasting (SB; 4 SB + SL; 5 10% hydrofluoric acid treatment (HF; 6 HF + SL. Before and after treatments, surface roughness was measured by a profilometer (Ra, µm. Drop volumes (10 µl of the adhesive systems were deposited onto substrates with a micropipette to observe materials spreading during 30s. Data were expressed in mm/s as spreading velocity. Statistical significances among groups were analyzed using one-way and two-way-ANOVA designs and the SNK test. RESULTS: Significant differences in spreading velocity were found between materials (p OBJETIVO: Determinar a rugosidade de superficies submetidas a diferentes tratamentos e correlacionar rugosidade com velocidade de escoamento de sistemas adesivos MATERIAL AND MÉTODOS: Lâminas de vidro foram utilizadas como substrato para avaliar a velocidade de escoamento dos sistemas adesivos Single Bond and Prime & Bond NT. Seis diferentes tratamentos de superfície foram comparados: 1- sem tratamento; 2 - silanização (SL; 3 - jateamento (J; 4 - J + SL; 5 - condicionamento com ácido fluorídrico a 10% (HF; 6 - HF + SL. Antes e após os tratamentos, foi mensurada a rugosidade das superficies (Ra, µm. Gotas de 10 µl de adesivo foram despositadas sobre as superficies e as velocidades de escoamento foram observadas durante 30 seg. Dados de velocidade de escoamento foram expressos em mm/s. Significâncias estatísticas entre grupos foram analisadas pelos testes ANOVA (um e dois critérios e SNK. RESULTADOS: Houve diferenças significantes na velocidade de escoamento entre materiais (p < 0.001 e entre

  6. Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey

    OpenAIRE

    Martin, Emily C.; Mace, Gregory N.; McLean, Ian S.; Logsdon, Sarah E.; Rice, Emily L.; Kirkpatrick, J. Davy; Burgasser, Adam J.; McGovern, Mark R.; Prato, Lisa

    2017-01-01

    We combine 131 new medium-resolution (R ~ 2000) J-band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5–T9. Specifically, we use an established set of spectral indices to determine surface gravity classifications for all of the M6–L7 objects in our sample by measuring the equivalent widths (EW) of the...

  7. Measurement of near-surface seismic compressional wave velocities using refraction tomography at a proposed construction site on the Presidio of Monterey, California

    Science.gov (United States)

    Powers, Michael H.; Burton, Bethany L.

    2012-01-01

    The U.S. Army Corps of Engineers is determining the feasibility of constructing a new barracks building on the U.S. Army Presidio of Monterey in Monterey, California. Due to the presence of an endangered orchid in the proposed area, invasive techniques such as exploratory drill holes are prohibited. To aid in determining the feasibility, budget, and design of this building, a compressional-wave seismic refraction survey was proposed by the U.S. Geological Survey as an alternative means of investigating the depth to competent bedrock. Two sub-parallel profiles were acquired along an existing foot path and a fence line to minimize impacts on the endangered flora. The compressional-wave seismic refraction tomography data for both profiles indicate that no competent rock classified as non-rippable or marginally rippable exists within the top 30 feet beneath the ground surface.

  8. Surface Radiation Survey at the Shepley’s Hill Remediation Site, Devens, Massachusettes

    Energy Technology Data Exchange (ETDEWEB)

    J. R. Giles; C. P. Oertel; L. G. Roybal

    2009-09-01

    The Idaho National Laboratory (INL) provided technical support for ongoing environmental remediation activities at the Shepley’s Hill remediation site, near Devens, MA. The technical support included the completion of a radiation survey of naturally occurring radioactive materials (NORM) at Shepley’s Hill, Shepley’s Hill landfill cover, and Red Cove areas. The objective of the radiation survey was to assess the ability of the INL backpack sodium iodide spectroscopy (BaSIS) system to detect elevated levels of NORM that may be associated with radon-222 emanation from near surface and subsurface fractures in the area. It is postulated that these fracture zones provide subsurface conduits for the transport of environmental contaminants. As such, location of these fracture sets will proved EPA Region 1 with the means for completing the development of an accurate site conceptual model. The results of the radiological survey show that some of the radiological anomalies correlate with currently mapped rock outcrops; however, not all of the rock outcrops in the surveyed area have been mapped. As such, it is not conclusive that all of the radiological anomalies correspond with surface rock outcrops. EPA Region 1 intends to perform a more comprehensive correlation of the radiation data collected with the BaSIS system with additional data sets such as detailed bedrock structural mapping, 2-dimensional resistivity profiling, and high-resolution topographic mapping. The results of this effort will be used in consideration of designing a potential follow-on effort for mapping of radon.

  9. Surface Elevation Changes and Velocities from Remote-Sensing Data at Vil'kitskogo, Inostranzeva and Bunge Glaciers on the Novaya Zemlya Icefield in the Russian High Arctic

    Science.gov (United States)

    Melkonian, A. K.; Willis, M. J.; Pritchard, M. E.; Stewart, A.

    2013-12-01

    The Northern Ice Cap of Novaya Zemlya is the largest (22,000 km2) and most rapidly changing ice cap in the Russian High Arctic, accounting for 80% of the region's estimated 0.025 mm/yr contribution to sea level rise between 2003-2009 (Moholdt et al., 2012). We use several remote sensing instruments to extend this time series forward and instead of computing a regional average, we seek a detailed glacier-by-glacier inventory of elevation and velocity changes. Here, we focus on three glaciers along the Barents Sea coast of the ice cap: Vil'kitskogo, Inostranzeva and Bunge, all of which experienced area reduction at an average rate of roughly 1 sq. km/yr from 1990 to 2000 (Kouraev, Legrésy and Remy, 2006). Our estimates of the current surface elevation change rates (dh/dt) and velocities at these glaciers will allow us to determine the connections between thinning, dynamics and the documented climatic changes -- 2004-2009 mean summer temperatures in Novaya Zemlya were anomalously high, +0.50×0.28C greater than mean summer temperatures from 1980-2009 (Moholdt et al., 2012), while Meng (2013) found that melt duration increased by 1.3 days/yr from 1996 to 2011. Based on warming and increased melt in the region, we expect to find a seasonally-related increase in velocity. Comparing acceleration (or the lack thereof) with thinning rates and combining both with existing bathymetry to calculate flux will enable us to estimate the contribution of dynamics to mass change at these glaciers relative to melt. We estimate dh/dt by applying a weighted linear regression to time series of ASTER DEMs acquired between 2003/07/29 to 2013/07/27 and Russian cartographic DEMs issued in 1970/71. Glacier velocities are calculated using automated normalized cross correlation, or 'pixel-tracking', applied to ASTER image pairs from 2003 to 2013. We supplement our ASTER time series with velocities and DEMs from very high-resolution (0.5-2 m/pixel) imagery acquired by QuickBird, WorldView and

  10. Velocities in Solar Pores

    Science.gov (United States)

    Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.

    1996-05-01

    We investigate the three dimensional structure of solar pores and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around pores with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in pores increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the pores appear near these boundaries. We analyze the vertical velocity structure in pores and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for pores. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.

  11. Three-dimensional surface velocities of Storstrømmen glacier, Greenland, derived from radar interferometry and ice-sounding radar measurements

    DEFF Research Database (Denmark)

    Reeh, Niels; Mohr, Johan Jacob; Madsen, Søren Nørvang

    2003-01-01

    in substantial errors (up to 20%) also on the south-north component of horizontal velocities derived by satellite synthetic aperture radar interferometry (InSAR) measurements. In many glacier environments, the steady-state vertical velocity component required to balance the annual ablation rate is 5-10 m a(-1...... tracks with airborne ice-sounding radar measurement of ice thickness. The results are compared to InSAR velocities previously derived by using the SPF assumption, and to velocities obtained by in situ global positioning system (GPS) measurements. The velocities derived by using the MC principle...

  12. Mapping 2000 2010 Impervious Surface Change in India Using Global Land Survey Landsat Data

    Science.gov (United States)

    Wang, Panshi; Huang, Chengquan; Brown De Colstoun, Eric C.

    2017-01-01

    Understanding and monitoring the environmental impacts of global urbanization requires better urban datasets. Continuous field impervious surface change (ISC) mapping using Landsat data is an effective way to quantify spatiotemporal dynamics of urbanization. It is well acknowledged that Landsat-based estimation of impervious surface is subject to seasonal and phenological variations. The overall goal of this paper is to map 200-02010 ISC for India using Global Land Survey datasets and training data only available for 2010. To this end, a method was developed that could transfer the regression tree model developed for mapping 2010 impervious surface to 2000 using an iterative training and prediction (ITP) approach An independent validation dataset was also developed using Google Earth imagery. Based on the reference ISC from the validation dataset, the RMSE of predicted ISC was estimated to be 18.4%. At 95% confidence, the total estimated ISC for India between 2000 and 2010 is 2274.62 +/- 7.84 sq km.

  13. Velocity pump reaction turbine

    Science.gov (United States)

    House, P.A.

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  14. Sodium Velocity Maps on Mercury

    Science.gov (United States)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  15. Wind-wave, velocity, and turbidity time-series data from Liberty Island (station LVB), Sacramento-San Joaquin Delta, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Time series data of water surface elevation, wave height, turbidity, and current and wave velocity were collected in Liberty Island beginning in August 2015 as part...

  16. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Science.gov (United States)

    How, Penelope; Benn, Douglas I.; Hulton, Nicholas R. J.; Hubbard, Bryn; Luckman, Adrian; Sevestre, Heïdi; van Pelt, Ward J. J.; Lindbäck, Katrin; Kohler, Jack; Boot, Wim

    2017-11-01

    Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  17. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Directory of Open Access Journals (Sweden)

    P. How

    2017-11-01

    Full Text Available Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  18. Mapping Impervious Surfaces Globally at 30m Resolution Using Global Land Survey Data

    Science.gov (United States)

    DeColstoun, Eric Brown; Huang, Chengquan; Tan, Bin; Smith, Sarah Elizabeth; Phillips, Jacqueline; Wang, Panshi; Ling, Pui-Yu; Zhan, James; Li, Sike; Taylor, Michael P.; hide

    2013-01-01

    Impervious surfaces, mainly artificial structures and roads, cover less than 1% of the world's land surface (1.3% over USA). Regardless of the relatively small coverage, impervious surfaces have a significant impact on the environment. They are the main source of the urban heat island effect, and affect not only the energy balance, but also hydrology and carbon cycling, and both land and aquatic ecosystem services. In the last several decades, the pace of converting natural land surface to impervious surfaces has increased. Quantitatively monitoring the growth of impervious surface expansion and associated urbanization has become a priority topic across both the physical and social sciences. The recent availability of consistent, global scale data sets at 30m resolution such as the Global Land Survey from the Landsat satellites provides an unprecedented opportunity to map global impervious cover and urbanization at this resolution for the first time, with unprecedented detail and accuracy. Moreover, the spatial resolution of Landsat is absolutely essential to accurately resolve urban targets such a buildings, roads and parking lots. With long term GLS data now available for the 1975, 1990, 2000, 2005 and 2010 time periods, the land cover/use changes due to urbanization can now be quantified at this spatial scale as well. In the Global Land Survey - Imperviousness Mapping Project (GLS-IMP), we are producing the first global 30 m spatial resolution impervious cover data set. We have processed the GLS 2010 data set to surface reflectance (8500+ TM and ETM+ scenes) and are using a supervised classification method using a regression tree to produce continental scale impervious cover data sets. A very large set of accurate training samples is the key to the supervised classifications and is being derived through the interpretation of high spatial resolution (approx. 2 m or less) commercial satellite data (Quickbird and Worldview2) available to us through the unclassified

  19. Mapping Impervious Surfaces Globally at 30m Resolution Using Landsat Global Land Survey Data

    Science.gov (United States)

    Brown de Colstoun, E.; Huang, C.; Wolfe, R. E.; Tan, B.; Tilton, J.; Smith, S.; Phillips, J.; Wang, P.; Ling, P.; Zhan, J.; Xu, X.; Taylor, M. P.

    2013-12-01

    Impervious surfaces, mainly artificial structures and roads, cover less than 1% of the world's land surface (1.3% over USA). Regardless of the relatively small coverage, impervious surfaces have a significant impact on the environment. They are the main source of the urban heat island effect, and affect not only the energy balance, but also hydrology and carbon cycling, and both land and aquatic ecosystem services. In the last several decades, the pace of converting natural land surface to impervious surfaces has increased. Quantitatively monitoring the growth of impervious surface expansion and associated urbanization has become a priority topic across both the physical and social sciences. The recent availability of consistent, global scale data sets at 30m resolution such as the Global Land Survey from the Landsat satellites provides an unprecedented opportunity to map global impervious cover and urbanization at this resolution for the first time, with unprecedented detail and accuracy. Moreover, the spatial resolution of Landsat is absolutely essential to accurately resolve urban targets such a buildings, roads and parking lots. With long term GLS data now available for the 1975, 1990, 2000, 2005 and 2010 time periods, the land cover/use changes due to urbanization can now be quantified at this spatial scale as well. In the Global Land Survey - Imperviousness Mapping Project (GLS-IMP), we are producing the first global 30 m spatial resolution impervious cover data set. We have processed the GLS 2010 data set to surface reflectance (8500+ TM and ETM+ scenes) and are using a supervised classification method using a regression tree to produce continental scale impervious cover data sets. A very large set of accurate training samples is the key to the supervised classifications and is being derived through the interpretation of high spatial resolution (~2 m or less) commercial satellite data (Quickbird and Worldview2) available to us through the unclassified

  20. Comparison of estimates of uncertainty of discharge at US geological survey index-velocity gages on the Chicago sanitary and ship canal, Illinois

    Science.gov (United States)

    Over, T.M.; Duncker, J.J.; Gonzalez-Castro, J. A.; ,

    2004-01-01

    Estimates of uncertainty of discharge at time scales from 5 minutes to 1 year were obtained for two index-velocity gages on the Chicago Sanitary and Ship Canal (CSSC), Ill., instrumented with acoustic velocity meters (AVMs). The velocity measurements obtained from the AVMs are corrected to a mean channel velocity by use of an index velocity rating (IVR). The IVR is a regression-derived relation between the AVM velocity estimates and those obtained using acoustic Doppler current profilers (ADCPs). The uncertainty estimation method is based on the first-order variance method, but the AVM velocity error is estimated from an empirical perspective, using the statistics of the IVR regression. Some uncertainty exists regarding whether to include the standard error of the IVR regression (????2) in the discharge uncertainty. At the 5-minute time scale when ?? ??2 is included, it has the dominant contribution to the discharge uncertainty, and the discharge uncertainty (expressed as the standard deviation of the discharge estimate) is about 5 m3/s at one gage and 8 m3/s at the other, independent of discharge. When ????2 is not included, the discharge uncertainty at the 5-minute time scale is much smaller (about 0.5 m3/s) and depends more strongly on discharge. For time scales one day or greater and when ????2 is not included, the uncertainty of the IVR parameters dominates the discharge uncertainty. The value of the discharge uncertainty is about 0.4 m3/s for one gage and 0.5 m3/s for the other gage at long time scales.

  1. Surface Water Quality Survey of Northern Indian River Lagoon from Sebastian Inlet to Mosquito Lagoon

    Science.gov (United States)

    Weaver, R. J.; Webb, B. M.

    2012-12-01

    Following news of an emerging brown tide algal bloom in the northern Indian River Lagoon (IRL), researchers sought to gain insight into the surface water quality in the IRL, as well as the extent of the algae coverage. A Portable SeaKeeper from YSI, mounted to a personal watercraft-based coastal profiling system, autonomously collected and analyzed the surface water. The system operates by recording sample data every 12 seconds while continuously underway at speeds up to and greater than 50 km/hr. The researchers covered a transect that started at Sebastian Inlet and followed a zig-zag path extending up through the Haulover Canal and into the Mosquito Lagoon. The survey path covered 166.7 km, and collected 2248 samples. Along the way stops were made at water quality stations used by the Saint John's River Water Management District, so that the data collected can be incorporated into ongoing monitoring efforts. The system analyzed the surface water for dissolved oxygen, pH, chlorophyll-a, salinity, temperature, turbidity, refined fuels, and CDOM. In the two days following the lagoon survey, the inlets at Port Canaveral and Sebastian were also surveyed for tidal currents and hydrography. The IRL transect survey data recorded evidence of the southern extent of the algae bloom in both chlorophyll-a and pH levels. Visual evidence of the bloom was striking as the water in the northern IRL turned a milk chocolaty brown color. Chlorophyll-a levels in the two inlets suggested bloom activity at these locations; however this bloom was different. This oceanic bloom was a result of a persistent upwelling event along the East Florida shelf, and the color was a paler green-yellow. The near-synoptic nature of the comprehensive lagoon survey, conducted in just over 7 hours, allows researchers to obtain a better understanding of water quality in coastal lagoons. Elevated levels of salinity, temperature, and refined fuels in the northern IRL indicate a low exchange rate and absence

  2. Sound velocity profiles (SVPs) in CSV format and PNG image format collected by the U.S. Geological Survey in the nearshore surrounding the Elizabeth Islands, MA

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS),...

  3. Sound velocity profile locations collected by the U.S. Geological Survey offshore of Fire Island, NY in 2011 (Geographic, WGS 84, Esri Point Shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS) mapped approximately 336 square kilometers of the lower shoreface and inner-continental shelf offshore of Fire Island, New York in...

  4. Very high precision survey equipment for great distances Surface surveys used to map out the surface network and the tunnelling machines then gyroscopically steered underground.

    CERN Multimedia

    1983-01-01

    At the beginning of the 1980s, CERN embarked on the enormous Large Electron-Positron Collider construction project. The excavation of the 27-kilometre LEP tunnel was a huge technical challenge. The tunnel-boring machines excavated the tunnel in 3.3 km octants and had to be operated with extraordinary precision to ensure that they reached their destination - the bottom of the next vertical shaft - precisely on target. The tunnel was excavated before high-performance instruments were developed for the construction of the Channel Tunnel. As no firms were willing to perform the surveying work, CERN's own surveyors, with experience from the SPS behind them, took up the challenge. At the surface, the surveyors established the world's most accurate geodetic network, performing measurements to an accuracy of 10-7, or 1mm per 10 km, using the Terrameter (see photo). The excavation of the tunnel was completed in 1988 and the finished tunnel's trajectory was found to diverge from the theoretical value specified by the p...

  5. General survey and conclusions with regard to the connection of water quantity and water quality studies of surface waters

    NARCIS (Netherlands)

    Rijtema, P.E.

    1979-01-01

    Publikatie die bestaat uit twee delen: 1. General survey of the relation between water quantity and water quality; 2. Conclusions with regard to the connection of water quantity and water quality studies of surface waters

  6. Capability assessment and challenges for quantum technology gravity sensors for near surface terrestrial geophysical surveying

    Science.gov (United States)

    Boddice, Daniel; Metje, Nicole; Tuckwell, George

    2017-11-01

    Geophysical surveying is widely used for the location of subsurface features. Current technology is limited in terms of its resolution (thus size of features it can detect) and penetration depth and a suitable technique is needed to bridge the gap between shallow near surface investigation using techniques such as EM conductivity mapping and GPR commonly used to map the upper 5 m below ground surface, and large features at greater depths detectable using conventional microgravity (> 5 m below ground surface). This will minimise the risks from unknown features buried in and conditions of the ground during civil engineering work. Quantum technology (QT) gravity sensors potentially offer a step-change in technology for locating features which lie outside of the currently detectable range in terms of size and depth, but that potential is currently unknown as field instruments have not been developed. To overcome this, a novel computer simulation was developed for a large range of different targets of interest. The simulation included realistic noise modelling of instrumental, environmental and location sources of noise which limit the accuracy of current microgravity measurements, in order to assess the potential capability of the new QT instruments in realistic situations and determine some of the likely limitations on their implementation. The results of the simulations for near surface features showed that the new technology is best employed in a gradiometer configuration as opposed to the traditional single sensor gravimeter used by current instruments due to the ability to suppress vibrational environmental noise effects due to common mode rejection between the sensors. A significant improvement in detection capability of 1.5-2 times was observed, putting targets such as mineshafts into the detectability zone which would be a major advantage for subsurface surveying. Thus this research, for the first time, has demonstrated clearly the benefits of QT gravity

  7. Seismic Velocity Estimation in the Middle East from Multiple Waveform Functionals: P & S Receiver Functions, Waveform Fitting, and Surface Wave Dispersion

    Science.gov (United States)

    2010-09-01

    senstivity to the uppermost mantle shear wave structure and to velocity contrasts across the Moho (Gangopadhyay et al., 2007). The amplitudes and signal-to...uppermost mantle shear wave structure and to velocity contrasts across the Moho (Gangopadhyay et al., 2007). Mutually satisfying constraints imposed by

  8. Microplastics Baseline Surveys at the Water Surface and in Sediments of the North-East Atlantic

    Directory of Open Access Journals (Sweden)

    Thomas Maes

    2017-05-01

    Full Text Available Microplastic contamination was determined in sediments of the Southern North Sea and floating at the sea surface of North West Europe. Floating concentrations ranged between 0 and 1.5 microplastic/m3, whereas microplastic concentrations in sediments ranged between 0 and 3,146 particles/kg dry weight sediment. In sediments, mainly fibers and spheres were found, whereas at the sea surface fragments were dominant. At the sea surface, concentrations of microplastics are lower and more variable than in sediments, meaning that larger sample sizes and water volumes are required to find detectable concentrations. We have calculated the widths of the confidence intervals (CI for different sample sizes, to give a first indication of the necessary sample size for a microplastic survey at the water surface. Higher concentrations of floating microplastics were found near estuaries. In sediments, estuaries and areas with a high organic carbon content were likely hotspots. Standardization of monitoring methods within marine regions is recommended to compare and assess microplastics pollution over time.

  9. Hammering Yucca Flat, Part Two: Shear-Wave Velocity

    Science.gov (United States)

    Finlay, T. S.; Abbott, R. E.; Knox, H. A.; Tang, D. G.; James, S. R.; Haney, M. M.; Hampshire, J. B., II

    2015-12-01

    In preparation for the next phase of the Source Physics Experiment (SPE), we conducted an active-source seismic survey of Yucca Flat, Nevada, on the Nevada National Security Site. Results from this survey will be used to inform the geologic models associated with the SPE project. For this study, we used a novel 13,000 kilogram weight-drop seismic source to interrogate an 18-km North-South transect of Yucca Flat. Source points were spaced every 200 meters and were recorded by 350 to 380 3-component 2-Hz geophones with variable spacings of 10, 20, and 100 meters. We utilized the Refraction-Microtremor (ReMi) technique to create multiple 1D dispersion curves, which were then inverted for shear-wave velocity profiles using the Dix inversion method (Tsai and Haney, 2015). Each of these 1D velocity models was subsequently stitched together to create a 2D profile over the survey area. The dispersion results indicate a general decrease in surface-wave phase velocity to the south. This result is supported by slower shear-wave velocity sediments and increasing basin depth towards the survey's southern extent. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  10. Scoping survey of perceived concerns, issues, and problems for near-surface disposal of FUSRAP waste

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, J.E.; Gilbert, T.L.

    1982-12-01

    This report is a scoping summary of concerns, issues, and perceived problems for near-surface disposal of radioactive waste, based on a survey of the current literature. Near-surface disposal means land burial in or within 15 to 20 m of the earth's surface. It includes shallow land burial (burial in trenches, typically about 6 m deep with a 2-m cap and cover) and some intermediate-depth land burial (e.g., trenches and cap similar to shallow land burial, but placed below 10 to 15 m of clean soil). Proposed solutions to anticipated problems also are discussed. The purpose of the report is to provide a better basis for identifying and evaluating the environmental impacts and related factors that must be analyzed and compared in assessing candidate near-surface disposal sites for FUSRAP waste. FUSRAP wastes are of diverse types, and their classification for regulatory purposes is not yet fixed. Most of it may be characterized as low-activity bulk solid waste, and is similar to mill tailings, but with somewhat lower average specific activity. It may also qualify as Class A segregated waste under the proposed 10 CFR 61 rules, but the parent radionuclides of concern in FUSRAP (primarily U-238 and Th-232) have longer half-lives than do the radionuclides of concern in most low-level waste. Most of the references reviewed deal with low-level waste or mill tailings, since there is as yet very little literature in the public domain on FUSRAP per se.

  11. Preliminary Analysis of M and L Dwarf Surface Gravities in the NIRSPEC Brown Dwarf Spectroscopic Survey

    Science.gov (United States)

    Martin, Emily C.; Mace, Gregory N.; McLean, Ian S.; Logsdon, Sarah E.; Rice, Emily L.

    2015-01-01

    Using previously published gravity-sensitive indices, we report on the analysis of near-infrared spectra for ˜ 80 M and L dwarfs . The spectra were obtained as part of the Brown Dwarf Spectroscopic Survey (BDSS) using NIRSPEC at the Keck Observatory, and each has a resolving power of R ˜ 2000 in the J band. With established gravity indices in the J band we can disentangle the degeneracy between temperature and age for brown dwarfs of various masses. By comparing a subset of the BDSS database with gravity indices defined at lower spectral resolution, we demonstrate that these indices also work well for higher resolution spectra. We then apply these techniques to M and L dwarfs in the BDSS to classify the diverse surface gravities of this large sample in a consistent manner. This analysis provides new age estimates for many M and L dwarfs, which will guide future studies of the young and old brown dwarf populations.

  12. Extensive survey of terrestrial organic carbon in surface sediments of the East Siberian Sea

    Science.gov (United States)

    Vonk, Jorien; Gustafsson, Örjan; Alling, Vanja; Sánchez-García, Laura; van Dongen, Bart; Andersson, Per; Dudarev, Oleg; Semiletov, Igor; Eglinton, Tim

    2010-05-01

    The East Siberian Sea (ESS) is the largest and shallowest continental shelf sea of the Arctic Ocean, yet it is the least explored. The perenially frozen tundra and taiga of the circum-Arctic coastal area holds approximately half of the global belowground carbon pool. Significant amounts of terrestrial organic carbon (terrOC) are exported with the Great Siberian Arctic rivers to the shelf seas. In addition, the carbon-rich, ice-bound Yedoma coasts in East Siberia release significant amounts of Pleistocene carbon through thermal degradation and coastal erosion. The fate of these large-scale releases of terrOC in the East Siberian Shelf Sea is still poorly understood. The urgency of this research is accentuated by the fact that the East-Siberian Arctic landmass is experiencing the strongest climate warming on Earth, with a great potential for various carbon-climate feedback links. During the International Siberian Shelf Study 2008 (ISSS-08), a 50-day research expedition onboard the Russian vessel Yakob Smirnitskiy in late summer 2008, we obtained surface sediments from over 60 ESS locations. The data obtained after bulk analyses of these sediments are combined with results obtained from previous ESS campaigns in 2003 and 2004 to facilitate a comprehensive investigation of the ESS surface sediment composition. Sedimentary OC contents were between 0.13 and 3.7% (median 1.02%, interquartile range 0.563) with the highest values near the Indigirka and Kolyma river mouths and in the Long Strait. Stable carbon isotope values were in the range of -27.4 to -21.2 per mill (median -25.3 per mill, interquartile range 2.04), with more depleted values close to the coast. A clear transition was observed east of 170° E with more enriched values, signalling a regime shift with stronger influence of the Pacific Ocean. The terrOC fraction in the surface sediments was estimated from the 13C data to be on average 70% for ESS as a whole, with maximal values of 90-100% (along most of the

  13. Rectification of Image Velocity Results (RIVeR): A simple and user-friendly toolbox for large scale water surface Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV)

    Science.gov (United States)

    Patalano, Antoine; García, Carlos Marcelo; Rodríguez, Andrés

    2017-12-01

    LSPIV (Large Scale Particle Image Velocimetry) and LSPTV (Large Scale Particle Tracking Velocimetry) are used as relatively low-cost and non-intrusive techniques for water-surface velocity analysis and flow discharge measurements in rivers or large-scale hydraulic models. This paper describes a methodology based on state-of-the-art tools (for example, that apply classical PIV/PTV analysis) resulting in large-scale surface-flow characterization according to the first operational version of the RIVeR (Rectification of Image Velocity Results). RIVeR is developed in Matlab and is designed to be user-friendly. RIVeR processes large-scale water-surface characterization such as velocity fields or individual trajectories of floating tracers. This work describes the wide range of application of the techniques for comparing measured surface flows in hydraulic physical models to flow discharge estimates for a wide range of flow events in rivers (for example, low and high flows).

  14. Extrapolation of cardiac index from analysis of the left ventricular outflow velocities in children: implication of the relationship between aortic size and body surface area.

    Science.gov (United States)

    Wodey, Eric; Senhadji, Lotfi; Carre, François; Ecoffey, Claude

    2002-03-01

    It has recently been reported in critically ill patients that a linear relationship exists between cardiac index (CI) measured with thermodilution and mean aortic blood flow velocity (MAFV). This hypothesis can be validated mathematically only if the aortic area (AA index) indexed to body surface area (BSA) remains constant and if the relationship between aortic diameter (PhiAo) and BSA is nonlinear. However, several other equations have described the relationship between BSA and, respectively, PhiAo and aortic area (AA) in children. The aim of this study was to determine if the relationships calculated between BSA and aortic size in children (without left ventricular outflow tract abnormality) could validate the hypothesis that MAFV and CI are well linked linearly, leading to its use to determine CI. Two hundred and thirty-two measurements performed in 126 children and infants were retrospectively analysed. PhiAo was measured in the long axis view at the annulus using two-dimensional mode echocardiography with a 5-MHz transducer. Various linear and nonlinear relationships between BSA and, respectively, PhiAo, PhiAoindex, AA and AAindex were determined based on a nonlinear regression method with a model as follows: y=a(xc) + b. The comparisons between regressions were conducted based on the estimation error. The relationships between PhiAo and BSA appeared nonlinear and was well described by: PhiAo=2.96(BSA1/4) - 1.31 with a non-zero y-intercept and PhiAo=1.64(BSA1/2) with a zero y-intercept. In contrast, the relationships between AA and BSA were linear. The AAindex was not linked to BSA and can be considered as constant. The coefficient a of the equation appeared similar to those obtained mathematically with the relationship previously described between MAFV and CI. The hypothesis that CI can be extrapolated to the measurement of MAFV appears valid as regards the relationships calculated between aortic size and BSA in children without left ventricular outflow

  15. A portable UAV LIDAR system for coastal topographic surveys and sea surface measurements

    Science.gov (United States)

    Huang, Zhi-Cheng; Liu, Philip L.-F.; Tseng, Kuo-Hsin; Yeh, Sunny

    2017-04-01

    A light-weight UAV system for coastal topography and coastal sea surface measurements is developed. This system is based on techniques of a multirotor UAV, a light detection and ranging (LIDAR), an inertial measurement unit, and a real-time kinematic global navigation satellite system (RTK-GNSS). The synchronization and data recording are achieved using Labview. This system can be operated in a very low attitude flight within a range of 10m that can provide very high resolution of point cloud data. The performance of this system has been tested and calibrated with known targets. The vertical root-mean-square error is less than about 10 cm, depending on the flight height. Applications of the system, including coastal topographic surveys, tidal elevation measurement, wave measurements, and bottom roughness measurements are presented and discussed. The tide and wave measurements are compared with in-situ measurements using pressure sensors. The results of comparison suggest that this system is a useful tool to measure the sea surface elevation and topography. The challenges of applying this system are also discussed.

  16. Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey

    Science.gov (United States)

    Martin, Emily C.; Mace, Gregory N.; McLean, Ian S.; Logsdon, Sarah E.; Rice, Emily L.; Kirkpatrick, J. Davy; Burgasser, Adam J.; McGovern, Mark R.; Prato, Lisa

    2017-03-01

    We combine 131 new medium-resolution (R ˜ 2000) J-band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5-T9. Specifically, we use an established set of spectral indices to determine surface gravity classifications for all of the M6-L7 objects in our sample by measuring the equivalent widths (EW) of the K I lines at 1.1692, 1.1778, and 1.2529 μm, and the 1.2 μm FeH J absorption index. Our results are consistent with previous surface gravity measurements, showing a distinct double peak—at ˜L5 and T5—in K I EW as a function of spectral type. We analyze the K I EWs of 73 objects of known ages and find a linear trend between log(Age) and EW. From this relationship, we assign age ranges to the very low gravity, intermediate gravity, and field gravity designations for spectral types M6-L0. Interestingly, the ages probed by these designations remain broad, change with spectral type, and depend on the gravity-sensitive index used. Gravity designations are useful indicators of the possibility of youth, but current data sets cannot be used to provide a precise age estimate. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  17. The VLT-FLAMES Tarantula Survey. XXV. Surface nitrogen abundances of O-type giants and supergiants

    Science.gov (United States)

    Grin, N. J.; Ramírez-Agudelo, O. H.; de Koter, A.; Sana, H.; Puls, J.; Brott, I.; Crowther, P. A.; Dufton, P. L.; Evans, C. J.; Gräfener, G.; Herrero, A.; Langer, N.; Lennon, D. J.; van Loon, J. Th.; Markova, N.; de Mink, S. E.; Najarro, F.; Schneider, F. R. N.; Taylor, W. D.; Tramper, F.; Vink, J. S.; Walborn, N. R.

    2017-04-01

    Context. Theoretically, rotation-induced chemical mixing in massive stars has far reaching evolutionary consequences, affecting the sequence of morphological phases, lifetimes, nucleosynthesis, and supernova characteristics. Aims: Using a sample of 72 presumably single O-type giants to supergiants observed in the context of the VLT-FLAMES Tarantula Survey (VFTS), we aim to investigate rotational mixing in evolved core-hydrogen burning stars initially more massive than 15 M⊙ by analysing their surface nitrogen abundances. Methods: Using stellar and wind properties derived in a previous VFTS study we computed synthetic spectra for a set of up to 21 N ii-v lines in the optical spectral range, using the non-LTE atmosphere code FASTWIND. We constrained the nitrogen abundance by fitting the equivalent widths of relatively strong lines that are sensitive to changes in the abundance of this element. Given the quality of the data, we constrained the nitrogen abundance in 38 cases; for 34 stars only upper limits could be derived, which includes almost all stars rotating at νesini> 200 km s-1. Results: We analysed the nitrogen abundance as a function of projected rotation rate νesini and confronted it with predictions of rotational mixing. We found a group of N-enhanced slowly-spinning stars that is not in accordance with predictions of rotational mixing in single stars. Among O-type stars with (rotation-corrected) gravities less than log gc = 3.75 this group constitutes 30-40 percent of the population. We found a correlation between nitrogen and helium abundance which is consistent with expectations, suggesting that, whatever the mechanism that brings N to the surface, it displays CNO-processed material. For the rapidly-spinning O-type stars we can only provide upper limits on the nitrogen abundance, which are not in violation with theoretical expectations. Hence, the data cannot be used to test the physics of rotation induced mixing in the regime of high spin rates

  18. Boat-based water-surface cross sectional elevation surveys along the upper Willamette River, Oregon, in Spring, 2015

    Science.gov (United States)

    Lind, Greg D.; Wellman, Roy; Mangano, Joseph F.

    2016-01-01

    Water-surface elevation measurements were collected in Spring, 2015 along the upper Willamette River, Oregon, between Harrisburg and Corvallis. These surveys were collected over a small range of discharges, from 6,900 cubic feet per second to 8,300 cubic feet per second, using a real-time kinematic global positioning system (RTK-GPS) on a motorboat at various cross sections along the river. These datasets were collected for equipment calibration and validation for the National Aeronautics and Space Administration’s (NASA) Surface Water and Ocean Topography (SWOT) satellite mission. This is one of multiple survey datasets that will be released for this effort.

  19. A Velocity Prediction Procedure for Sailing Yachts with a hydrodynamic Model based on integrated fully coupled RANSE-Free-Surface Simulations

    NARCIS (Netherlands)

    Boehm, C.

    2014-01-01

    One of the most important tools in today's sailing yacht design is the Velocity Prediction Program (VPP). VPPs calculate boat speed from the equilibrium of aero- and hydrodynamic flow forces. Consequently their accuracy is linked to the accuracy of the aero- and hydrodynamic data used to represent a

  20. A Velocity Prediction Procedure for Sailing Yachts with a hydrodynamic Model based on integrated fully coupled RANSE-Free-Surface Simulations

    OpenAIRE

    Boehm, C.

    2014-01-01

    One of the most important tools in today's sailing yacht design is the Velocity Prediction Program (VPP). VPPs calculate boat speed from the equilibrium of aero- and hydrodynamic flow forces. Consequently their accuracy is linked to the accuracy of the aero- and hydrodynamic data used to represent a yacht. These data are usually derived from Experimental Fluid Dynamics (EFD) or Computational Fluid Dynamics (CFD) results and processed by means of linearisation and interpolation to represent th...

  1. Comparison of Blue Wavelengths and Scan Velocity Effects on the Detection of Enamel Surface Caries Using Steady-State Laser-Induced Autofluorescence Spectroscopy

    Science.gov (United States)

    Khosroshahi, M. E.; Khoi, N. Taghizadeh

    2014-05-01

    The results of sound and carious enamel fl uorescence emission study using (i) different blue wavelengths, (ii) different scan velocity, and (iii) spectral ratio are reported. The samples were irradiated using a tunable argon laser emitting at 459 and 488 nm and a 405 nm laser at two different scan velocities of 0.23 and 0.5 mm/s. The results showed a spectral band of 443-492 nm for 405 nm, 493-522 nm for 459 nm, and 526-625 nm for 488 nm lasers for sound teeth. It was found from the emission spectra that with increase in the excitation wavelength, the corresponding primary peaks of the carious samples showed Stokes shifts of 4, 6, and 2 nm, respectively. No signifi cant change was observed for the secondary peaks. Also, in all cases, the intensity of fl uorescence signals of sound teeth was higher than those of carious teeth. The highest shape factor of 1.82 and integrated intensity ratio of 1.20 were achieved at 405 nm, which provides relatively better tissue discrimination. Also, increasing the scan velocity reduced the signal amplitudes in both sound and carious samples.

  2. Survey of surface proteins from the pathogenic Mycoplasma hyopneumoniae strain 7448 using a biotin cell surface labeling approach.

    Directory of Open Access Journals (Sweden)

    Luciano Antonio Reolon

    Full Text Available The characterization of the repertoire of proteins exposed on the cell surface by Mycoplasma hyopneumoniae (M. hyopneumoniae, the etiological agent of enzootic pneumonia in pigs, is critical to understand physiological processes associated with bacterial infection capacity, survival and pathogenesis. Previous in silico studies predicted that about a third of the genes in the M. hyopneumoniae genome code for surface proteins, but so far, just a few of them have experimental confirmation of their expression and surface localization. In this work, M. hyopneumoniae surface proteins were labeled in intact cells with biotin, and affinity-captured biotin-labeled proteins were identified by a gel-based liquid chromatography-tandem mass spectrometry approach. A total of 20 gel slices were separately analyzed by mass spectrometry, resulting in 165 protein identifications corresponding to 59 different protein species. The identified surface exposed proteins better defined the set of M. hyopneumoniae proteins exposed to the host and added confidence to in silico predictions. Several proteins potentially related to pathogenesis, were identified, including known adhesins and also hypothetical proteins with adhesin-like topologies, consisting of a transmembrane helix and a large tail exposed at the cell surface. The results provided a better picture of the M. hyopneumoniae cell surface that will help in the understanding of processes important for bacterial pathogenesis. Considering the experimental demonstration of surface exposure, adhesion-like topology predictions and absence of orthologs in the closely related, non-pathogenic species Mycoplasma flocculare, several proteins could be proposed as potential targets for the development of drugs, vaccines and/or immunodiagnostic tests for enzootic pneumonia.

  3. SURVEY

    DEFF Research Database (Denmark)

    SURVEY er en udbredt metode og benyttes inden for bl.a. samfundsvidenskab, humaniora, psykologi og sundhedsforskning. Også uden for forskningsverdenen er der mange organisationer som f.eks. konsulentfirmaer og offentlige institutioner samt marketingsafdelinger i private virksomheder, der arbejder...

  4. Velocity bias induced by flow patterns around ADCPs and associated deployment platforms

    Science.gov (United States)

    Mueller, David S.

    2015-01-01

    Velocity measurements near the Acoustic Doppler Current Profiler (ADCP) are important for mapping surface currents, measuring velocity and discharge in shallow streams, and providing accurate estimates of discharge in the top unmeasured portion of the water column. Improvements to ADCP performance permit measurement of velocities much closer (5 cm) to the transducer than has been possible in the past (25 cm). Velocity profiles collected by the U.S. Geological Survey (USGS) with a 1200 kHz Rio Grande Zedhead ADCP in 2002 showed a negative bias in measured velocities near the transducers. On the basis of these results, the USGS initiated a study combining field, laboratory, and numerical modeling data to assess the effect of flow patterns caused by flow around the ADCP and deployment platforms on velocities measured near the transducers. This ongoing study has shown that the negative bias observed in the field is due to the flow pattern around the ADCP. The flow pattern around an ADCP violates the basic assumption of flow homogeneity required for an accurate three-dimensional velocity solution. Results, to date (2014), have indicated velocity biases within the measurable profile, due to flow disturbance, for the TRDI 1200 kHz Rio Grande Zedhead and the SonTek RiverSurveyor M9 ADCPs. The flow speed past the ADCP, the mount and the deployment platform have also been shown to play an important role in the magnitude and extent of the velocity bias.

  5. ROSS: The Remotely-Operated Surface Sampler - A MediumEndurance, Precision-Navigated Platform Optimized for Uncontaminated Measurement of Upper-Ocean Velocity, Density and Turbulence

    Science.gov (United States)

    2015-09-30

    salinity and velocity at high vertical  and horizontal   resolution. The first set of extended open-­‐ocean   testing and data  collection...unlimited. 1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. keel  and waterproof...other sensor systems (Figure 2).   The system was tested in Apri off the  Oregon  Coast in 30 knots of wind and seven-­‐foot seas,  and  then

  6. Analytical and Mathematical Modeling and Optimization of Fiber Metal Laminates (FMLs subjected to low-velocity impact via combined response surface regression and zero-One programming

    Directory of Open Access Journals (Sweden)

    Faramarz Ashenai Ghasemi

    Full Text Available This paper presents analytical and mathematical modeling and optimization of the dynamic behavior of the fiber metal laminates (FMLs subjected to low-velocity impact. The deflection to thickness (w/h ratio has been identified through the governing equations of the plate that are solved using the first-order shear deformation theory as well as the Fourier series method. With the help of a two degrees-of-freedom system, consisting of springs-masses, and the Choi's linearized Hertzian contact model the interaction between the impactor and the plate is modeled. Thirty-one experiments are conducted on samples of different layer sequences and volume fractions of Al plies in the composite Structures. A reliable fitness function in the form of a strict linear mathematical function constructed. Using an ordinary least square method, response regression coefficients estimated and a zero-one programming technique proposed to optimize the FML plate behavior subjected to any technological or cost restrictions. The results indicated that FML plate behavior is highly affected by layer sequences and volume fractions of Al plies. The results also showed that, embedding Al plies at outer layers of the structure significantly results in a better response of the structure under low-velocity impact, instead of embedding them in the middle or middle and outer layers of the structure.

  7. Surface-water quality-assurance plan for the U.S. Geological Survey Washington Water Science Center

    Science.gov (United States)

    Mastin, Mark C.

    2016-02-19

    This Surface-Water Quality-Assurance Plan documents the standards, policies, and procedures used by the U.S. Geological Survey Washington Water Science Center (WAWSC) for activities related to the collection, processing, storage, analysis, and publication of surface-water data. This plan serves as a guide to all WAWSC personnel involved in surface-water data activities, and changes as the needs and requirements of the WAWSC change. Regular updates to this plan represent an integral part of the quality-assurance process. In the WAWSC, direct oversight and responsibility by the hydrographer(s) assigned to a surface-water station, combined with team approaches in all work efforts, assure highquality data, analyses, reviews, and reports for cooperating agencies and the public.

  8. A survey of Cr(VI) contamination of surface water in the proximity of ...

    African Journals Online (AJOL)

    In this study, Cr(VI) levels present in surface water within the vicinity of ferrochrome smelters located in the Bushveld Igneous Complex were monitored for a period of 1 year. The results indicated that surface water in the proximity of ferrochrome smelters was mostly unaffected by Cr(VI) pollution. Two surface water sampling ...

  9. Computing discharge using the index velocity method

    Science.gov (United States)

    Levesque, Victor A.; Oberg, Kevin A.

    2012-01-01

    Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression

  10. Radial-Velocity Variability of the Sun as a Star with HAPRS And HAPRS-N

    Science.gov (United States)

    Haywood, Raphaëlle D.; Collier Cameron, Andrew; Dumusque, Xavier; Glenday, Alex; Latham, David W.; Lovis, Christophe; Maldonado, Jesus; Micela, Giusi; Molinari, Emiliano; Mortier, Annelies; Pepe, Francesco; Phillips, David F.; Udry, Stephane

    2016-06-01

    Since we can resolve the surface of the Sun directly, we can explore the origin of radial-velocity variations induced by individual solar surface features such as faculae/plage, sunspots and granulation.I will present my recent investigation of the radial-velocity variations of the Sun as a star, based on high-resolution HARPS spectra of reflected sunlight and simultaneous images from the Solar Dynamics Observatory. We found that faculae are the dominant source of activity-induced radial-velocity variations, via suppression of convective blueshift. We investigated possible proxies for activity-induced radial-velocity variations and found that optical lightcurves can only provide a partial representation of these signals; the full-disc magnetic flux, however, is an excellent tracer. In addition to this dataset, the HARPS-N spectrograph has been operating with a new solar telescope feed since 2015 July. I will present results from the first year observations, which show radial-velocity variations of up to 7-8 m/s.Identifying proxies for solar radial-velocity variations is key to understanding the radial-velocity variability of other Sun-like stars, and is also essential for other investigations such as exoplanet detection surveys.

  11. Cavitation resistance of surface composition "Steel-Ni-TiNi-TiNiZr-cBNCo", formed by High-Velocity Oxygen-Fuel spraying

    Science.gov (United States)

    Blednova, Zh. M.; Dmitrenko, D. V.; Balaev, E. U. O.

    2018-01-01

    The object of the study is a multilayered surface composition "Steel - a Multicomponent material with Shape Memory Effect - a wear-resistant layer" under conditions of cavitation effects in sea water. Multicomponent TiNi-based coatings with addition of alloying elements such as Zr in an amount up to 10% mass, allow to create a composite material with a gradient of properties at the interface of layers, which gives new properties to coatings and improves their performance significantly. The use of materials with shape memory effect (SME) as surface layers or in the composition of surface layered compositions allows to provide an effective reaction of materials to the influence of external factors and adaptation to external influences. The surface composite layer cBN-10%Co has high hardness and strength, which ensures its resistance to shock cyclic influences of collapsing caverns. The increased roughness of the surface of a solid surface composite in the form of strong columnar structures ensures the crushing of vacuum voids, redistributing their effect on the entire surface, and not concentrating them in certain zones. In addition, the gradient structure of the multilayer composite coating TiNi–Ti33Ni49Zr18–cBN-10%Co Co makes it possible to create conditions for the relaxation of stresses created by the variable impact load of cavitation caverns and the manifestation of compensating internal forces due to thermo-elastic martensitic transformations of SME materials. The cavitation resistance of the coating TiNi–Ti33Ni49Zr18–cBN-10%Co according to the criterion of mass wear is 15-20 times higher than that of the base material without coating and 10-12 times higher than that of the TiNi-TiNiZr coating. The proposed architecture of the multifunctional gradient composition, "steel-Ni-TiNi– Ti33Ni49Zr18–cBN-10%Co", each layer of which has its functional purpose, allows to increase the service life of parts operating under conditions of cavitation

  12. Surface geochemical survey for geothermal exploration in the south-east zone of Tenerife Island, Canary Islands

    Science.gov (United States)

    Diaz Requejo, M.; Marrero, R.; Padron, E.; Melian, G.; Guerrero, V.; Hernandez Perez, P. A.; Perez, N.; Hidalgo, R.

    2009-12-01

    Water and gas sampling of natural discharges are the most common type of geochemical surveys for geothermal exploration. However, these natural discharges are generally scarces at geothermal exploration areas where the extent of the field is not known. Therefore, soil-volatile (Hg, As, Sb, NH3 and B) and soil-gas surveys (222Rn, CO2, He, H2, CH4, O2, Ar) are becoming a useful geochemical tool to identify permeable areas and potential upflow or boiling zones. These surveys can also help to delineate the margins of a geothermal system, and therefore often complement geophysical surveys particularly where the interpretation of geophysical data shows some difficulties. During July and August, 2008, a surface geochemical survey was undertaken in a ~120 km2 area at the south-east slope of Tenerife Island, Spain. In order to obtain a representative distribution of the whole study area, during the field work a total of 577 sampling points were performed. In-situ measurement of radon (222Rn) and thoron (220Rn) activities together with Hg0 and H2S gas concentration and CO2 and H2S soil effluxes were performed at each sampling point. At the same time, gas samples were taken from the soil atmosphere at 40 cm depth for subsequent chemical analysis by means of micro-gas chromatography and quadrupole mass spectrometry (He, H2, Ne, N2, CO2, CH4, Ar and CO2). At least two geochemical anomalous zones have been identified in the present work: (A) one close to Siete Fuentes-Fasnia historical vents (1704-1705 AD) and (B) located on the southwestern limit of the study area. Relatively high concentrations of H2 and ΔHe as well as high H2/Ar and He/CO2 ratios were observed at both zones, indicating a clear evidence of the existence of an upflow zone with an important contribution of endogenous gases. The existence of a volcanic-hydrothermal system coupled with a vertical permeability structures in both zones could explain these geochemical anomalies observed in the surface environment

  13. EarthFinder: A Precise Radial Velocity Survey Probe Mission of our Nearest Stellar Neighbors for Earth-Mass Habitable Zone Analogs Using High-Resolution UV-Vis-NIR Echelle Spectroscopy on a Space Platform

    Science.gov (United States)

    Plavchan, Peter; EarthFinder Team

    2018-01-01

    We are investigating the science case for a 1.0-1.4 meter space telescope to survey the closest, brightest FGKM main sequence stars to search for Habitable Zone (HZ) Earth analogs using the precise radial velocity (PRV) technique at a precision of 1-10 cm/s. Our baseline instrument concept uses two diffraction-limited spectrographs operating in the 0.4-1.0 microns and 1.0-2.4 microns spectral regions each with a spectral resolution of R=150,000~200,000, with the possibility of a third UV arm. Because the instrument utilizes a diffraction-limited input beam, the spectrograph would be extremely compact, less than 50 cm on a side, and illumination can be stabilized with the coupling of starlight into single mode fibers. With two octaves of wavelength coverage and a cadence unimpeded by any diurnal, seasonal, and atmospheric effects, EarthFinder will offer a unique platform for recovering stellar activity signals from starspots, plages, granulation, etc. to detect exoplanets at velocity semi-amplitudes currently not obtainable from the ground. Variable telluric absorption and emission lines may potentially preclude achieving PRV measurements at or below 10 cm/s in the visible and Earth-trailing (e.g. Spitzer, Kepler) or Lagrange orbit, the space-based cadence of observations of a star can be year-round at the ecliptic poles, with two ~100-day "seasons" every 6 months in the ecliptic plane. This will provide a distinct advantage compared to an annual ~3-6 month observing season from the ground for mitigating stellar activity and detecting the orbital periods of HZ Earth-mass analogs (e.g. ~6-months to ~2 years). Finally, we are compiling a list of ancillary science cases for the observatory, ranging from asteroseismology to the direct measurement of the expansion of the Universe.

  14. Surface-wave separation and its impact on seismic survey design

    NARCIS (Netherlands)

    Ishiyama, T.

    2015-01-01

    Surface waves in seismic data are often dominant and mask primaries in land or shallow-water environments. Separating them from the primaries is of great importance either for removing them as noise for reservoir imaging and characterization, or for considering them as signal for near-surface

  15. The Relevance of Surface Roughness Data Qualities in Diagnostic Modeling of Wind Velocity in Complex Terrain: A Case Study from the Śnieżnik Massif (SW Poland)

    Science.gov (United States)

    Jancewicz, Kacper; Szymanowski, Mariusz

    2017-02-01

    Numerical modeling of wind velocity above complex terrain has become a subject of numerous contemporary studies. Regardless of the methodical approach (dynamic or diagnostic), it can be observed that information about surface roughness is indispensable to achieve realistic results. In this context, the current state of GIS and remote sensing development allows access to a number of datasets providing information about various properties of land coverage in a broad spectrum of spatial resolution. Hence, the quality of roughness information may vary depending on the properties of primary land coverage data. As a consequence, the results of the wind velocity modeling are affected by the accuracy and spatial resolution of roughness data. This paper describes further attempts to model wind velocity using the following sources of roughness information: LiDAR data (Digital Surface Model and Digital Terrain Model), database of topographical objects (BDOT10k) and both raster and vector versions of Corine Land Cover 2006 (CLC). The modeling was conducted in WindStation 4.0.2 software which is based on the computational fluid dynamics (CFD) diagnostic solver Canyon. Presented experiment concerns three episodes of relatively strong and constant synoptic forcing: 26 November 2011, 25 May 2012 and 26 May 2012. The modeling was performed in the spatial resolution of 50 and 100 m. Input anemological data were collected during field measurements while the atmosphere boundary layer parameters were derived from the meteorological stations closest to the study area. The model's performance was verified using leave-one-out cross-validation and calculation of error indices such as bias error, root mean square error and index of wind speed. Thus, it was possible to compare results of using roughness datasets of different type and resolution. The study demonstrates that the use of LiDAR-based roughness data may result in an improvement of the model's performance in 100 and 50 m resolution

  16. THE RADIAL VELOCITY EXPERIMENT (RAVE): FOURTH DATA RELEASE

    Energy Technology Data Exchange (ETDEWEB)

    Kordopatis, G.; Gilmore, G. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Steinmetz, M.; Williams, M. E. K.; Piffl, T.; Enke, H.; Carrillo, I. [Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Boeche, C.; Roeser, S. [Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, D-69120 Heidelberg (Germany); Seabroke, G. M. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT (United Kingdom); Siebert, A. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); Zwitter, T. [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Binney, J. [Rudolf Peierls Centre for Theoretical Physics, Keble Road, Oxford, OX1 3NP (United Kingdom); De Laverny, P.; Recio-Blanco, A.; Bijaoui, A. [Laboratoire Lagrange, UMR 7293, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d' Azur, BP4229, F-06304 Nice (France); Wyse, R. F. G. [Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Freeman, K. [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Munari, U. [INAF National Institute of Astrophysics, Astronomical Institute of Padova, I-36012 Asiago (VI) (Italy); Anguiano, B., E-mail: gkordo@ast.cam.ac.uk [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); and others

    2013-11-01

    We present the stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity), radial velocities, individual abundances, and distances determined for 425,561 stars, which constitute the fourth public data release of the RAdial Velocity Experiment (RAVE). The stellar atmospheric parameters are computed using a new pipeline, based on the algorithms of MATISSE and DEGAS. The spectral degeneracies and the Two Micron All Sky Survey photometric information are now better taken into consideration, improving the parameter determination compared to the previous RAVE data releases. The individual abundances for six elements (magnesium, aluminum, silicon, titanium, iron, and nickel) are also given, based on a special-purpose pipeline that is also improved compared to that available for the RAVE DR3 and Chemical DR1 data releases. Together with photometric information and proper motions, these data can be retrieved from the RAVE collaboration Web site and the Vizier database.

  17. Conduction velocity of antigravity muscle action potentials.

    Science.gov (United States)

    Christova, L; Kosarov, D; Christova, P

    1992-01-01

    The conduction velocity of the impulses along the muscle fibers is one of the parameters of the extraterritorial potentials of the motor units allowing for the evaluation of the functional state of the muscles. There are no data about the conduction velocities of antigravity muscleaction potentials. In this paper we offer a method for measuring conduction velocity of potentials of single MUs and the averaged potentials of the interference electromiogram (IEMG) lead-off by surface electrodes from mm. sternocleidomastoideus, trapezius, deltoideus (caput laterale) and vastus medialis. The measured mean values of the conduction velocity of antigravity muscles potentials can be used for testing the functional state of the muscles.

  18. Colours of the Outer Solar System Origins Survey (Col-OSSOS): New Insights into Kuiper belt Surfaces

    Science.gov (United States)

    Schwamb, M. E.; Fraser, W. C.; Bannister, M. T.; Pike, R. E.; Marsset, M.; Kavelaars, J. J.; Benecchi, S.; Delsanti, A.; Lehner, M. J.; Thirouin, A.; Guilbert-Lepoutre, A.; Peixinho, N.; Vernazza, P.

    2016-12-01

    The icy planetesimals of the Kuiper belt inform our knowledge about the growth of planetary embryos and our Solar System's dynamical history. The majority of the known Pluto-sized Kuiper belt objects (KBOs) are bright enough for their surfaces to be studied through optical and infrared spectroscopy. But for the typical smaller r mag > 22 mag KBOs, we must rely on what colors reveal by proxy, and this picture of Kuiper belt surfaces remains incomplete. Previous studies in this size range examined the hodgepodge set of KBOs discovered by surveys with varying and sometimes unknown detection biases that make it challenging to explore the true frequency of surface colors within the Kuiper belt. The Colours of the Outer Solar System Origins Survey (Col-OSSOS) aims to explore and explain the compositional variety within the Kuiper belt through near simultaneous u, g,r and J colors with the Gemini North Telescope and the Canada-France-Hawaii Telescope. The survey targets KBOs brighter than 23.6 r' mag ( 50-300 km) found by the Outer Solar System Origins Survey (OSSOS). With Col-OSSOS, we have a set of colors measured for a KBO sample discovered in a brightness limited survey, with a well-measured detection efficiency. Col-OSSOS will provide a compositional-dynamical map of the Kuiper belt in which to study the end of stages of Neptune migration and the conditions of the early planetesimal disk where these small icy bodies formed. We will give an overview of Col-OSSOS and an update on the program's current status. We will present the photometry from the first 30 KBOs studied from the first complete OSSOS block and examine the implications for Kuiper belt surfaces. We derive the observed and debiased ratio of neutral to red KBOs, measure the masses of the three color populations within the Kuiper belt (the red and neutral dynamically excited population and the red cold classical belt), and explore the radial color distribution in the primordial planetesimal disk before

  19. The Radial Velocity Experiment (RAVE): Fourth Data Release

    NARCIS (Netherlands)

    Kordopatis, G.; Gilmore, G.; Steinmetz, M.; Boeche, C.; Seabroke, G. M.; Siebert, A.; Zwitter, T.; Binney, J.; de Laverny, P.; Recio-Blanco, A.; Williams, M. E. K.; Piffl, T.; Enke, H.; Roeser, S.; Bijaoui, A.; Wyse, R. F. G.; Freeman, K.; Munari, U.; Carrillo, I.; Anguiano, B.; Burton, D.; Campbell, R.; Cass, C. J. P.; Fiegert, K.; Hartley, M.; Parker, Q. A.; Reid, W.; Ritter, A.; Russell, K. S.; Stupar, M.; Watson, F. G.; Bienaymé, O.; Bland-Hawthorn, J.; Gerhard, O.; Gibson, B. K.; Grebel, E. K.; Helmi, A.; Navarro, J. F.; Conrad, C.; Famaey, B.; Faure, C.; Just, A.; Kos, J.; Matijevič, G.; McMillan, P. J.; Minchev, I.; Scholz, R.; Sharma, S.; Siviero, A.; de Boer, E. Wylie; Žerjal, M.

    2013-01-01

    We present the stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity), radial velocities, individual abundances, and distances determined for 425,561 stars, which constitute the fourth public data release of the RAdial Velocity Experiment (RAVE). The stellar

  20. The radial velocity experiment (RAVE) : Fourth data release

    NARCIS (Netherlands)

    Kordopatis, G.; Gilmore, G.; Steinmetz, M.; Boeche, C.; Seabroke, G. M.; Siebert, A.; Zwitter, T.; Binney, J.; de Laverny, P.; Recio-Blanco, A.; Williams, M. E. K.; Piffl, T.; Enke, H.; Roeser, S.; Bijaoui, A.; Wyse, R. F. G.; Freeman, K.; Munari, U.; Carrillo, I.; Anguiano, B.; Burton, D.; Campbell, R.; Cass, C. J. P.; Fiegert, K.; Hartley, M.; Parker, Q. A.; Reid, W.; Ritter, A.; Russell, K. S.; Stupar, M.; Watson, F. G.; Bienayme, O.; Bland-Hawthorn, J.; Gerhard, O.; Gibson, B. K.; Grebel, E. K.; Helmi, A.; Navarro, J. F.; Conrad, C.; Famaey, B.; Faure, C.; Just, A.; Kos, J.; Matijevic, G.; McMillan, P. J.; Minchev, I.; Scholz, R.; Sharma, S.; Siviero, A.; de Boer, E. Wylie; Zerjal, M.

    2013-01-01

    We present the stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity), radial velocities, individual abundances, and distances determined for 425,561 stars, which constitute the fourth public data release of the RAdial Velocity Experiment (RAVE). The stellar

  1. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...... estimator automatically compensates for the axial velocity, when determining the transverse velocity by using fourth order moments rather than second order moments. The estimation is optimized by using a lag different from one in the estimation process, and noise artifacts are reduced by using averaging...... of RF samples. Further, compensation for the axial velocity can be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce spatial velocity dispersion....

  2. A Survey on Methods for Reconstructing Surfaces from Unorganized Point Sets

    Directory of Open Access Journals (Sweden)

    Vilius Matiukas

    2011-08-01

    Full Text Available This paper addresses the issue of reconstructing and visualizing surfaces from unorganized point sets. These can be acquired using different techniques, such as 3D-laser scanning, computerized tomography, magnetic resonance imaging and multi-camera imaging. The problem of reconstructing surfaces from their unorganized point sets is common for many diverse areas, including computer graphics, computer vision, computational geometry or reverse engineering. The paper presents three alternative methods that all use variations in complementary cones to triangulate and reconstruct the tested 3D surfaces. The article evaluates and contrasts three alternatives.Article in English

  3. Washington Maritime NWRC: Initial Survey Instructions for Surface-nesting Seabird Monitoring

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In Region 1, the vast majority of seabirds nest on NWRs. Because seabirds are dependent on the marine environment and surface-nesters are easily observed on...

  4. Multichannel Analysis of Surface Waves and Down-Hole Tests in the Archeological "Palatine Hill" Area (Rome, Italy): Evaluation and Influence of 2D Effects on the Shear Wave Velocity

    Science.gov (United States)

    Di Fiore, V.; Cavuoto, G.; Tarallo, D.; Punzo, M.; Evangelista, L.

    2016-05-01

    A joint analysis of down-hole (DH) and multichannel analysis of surface waves (MASW) measurements offers a complete evaluation of shear wave velocity profiles, especially for sites where a strong lateral variability is expected, such as archeological sites. In this complex stratigraphic setting, the high "subsoil anisotropy" (i.e., sharp lithological changes due to the presence of anthropogenic backfill deposits and/or buried man-made structures) implies a different role for DH and MASW tests. This paper discusses some results of a broad experimental program conducted on the Palatine Hill, one of the most ancient areas of the city of Rome (Italy). The experiments were part of a project on seismic microzoning and consisted of 20 MASW and 11 DH tests. The main objective of this study was to examine the difficulties related to the interpretation of the DH and MASW tests and the reliability limits inherent in the application of the noninvasive method in complex stratigraphic settings. As is well known, DH tests provide good determinations of shear wave velocities (Vs) for different lithologies and man-made materials, whereas MASW tests provide average values for the subsoil volume investigated. The data obtained from each method with blind tests were compared and were correlated to site-specific subsurface conditions, including lateral variability. Differences between punctual (DH) and global (MASW) Vs measurements are discussed, quantifying the errors by synthetic comparison and by site response analyses. This study demonstrates that, for archeological sites, VS profiles obtained from the DH and MASW methods differ by more than 15 %. However, the local site effect showed comparable results in terms of natural frequencies, whereas the resolution of the inverted shear wave velocity was influenced by the fundamental mode of propagation.

  5. Since “Groundwater and Surface Water–A Single Resource”: some U.S. Geological Survey advances in modeling groundwater/surface-water interactions

    Directory of Open Access Journals (Sweden)

    Daniel Feinstein

    2012-06-01

    Full Text Available Field and interpretive studies conducted by T.C. Winter and U.S. Geological Survey colleagues, and summarized in the 1998 publication “Groundwater and Surface Water – A Single Resource”, inspired a new generation of research centered on extensions of the groundwater-flow code MODFLOW to more sophisticated simulation of coupled groundwater and surface-water systems. Guided by emerging concerns with water availability, safe yields from wells, health of aquatic habitat, and climate change, the changes to MODFLOW involve: 1 the ability to more precisely and accurately represent the interface between surface and subsurface flows and 2 the consideration of a variety of mechanisms that influence their interaction. A review of the most important changes to the code is supplemented in this article by selected case studies in an effort to show the scope of the advances. The updates discussed include the Streamflow Routing (SFR, Lake (LAK, and Unsaturated-Zone Flow (UZF Packages in MODFLOW-2005 and the Groundwater Management (GWM, Local Grid Refinement (LGR, and Newton (NWT formulation versions of MODFLOW-2005. New developments feature the integration of rainfall-runoff modeling with MODFLOW in GSFLOW, coupling of GFLOW and MODFLOW in a hybrid code, and the forthcoming unstructured grid version of MODFLOW. They promise continued advances in the ability to use science to protect the single water resource.

  6. Bacterial contamination of floors and other surfaces in operating rooms: a five-year survey.

    Science.gov (United States)

    Suzuki, A.; Namba, Y.; Matsuura, M.; Horisawa, A.

    1984-01-01

    Bacterial contamination of floors and other surfaces in the operating suite has been investigated by contact impression plates during the past five years. Colony counts of the floors of operating rooms, cleaned with disinfectant, were 3.3 c.f.u./10 cm2; on the floors of semi-clean and dirty areas, cleaned with detergent, colony counts were 44.8 and 71.4 c.f.u./10 cm2 respectively. The highest colony counts of 487.4 c.f.u./10 cm2 were found in the dressing rooms, the floors of which were covered with carpets, cleaned with a vacuum cleaner. Mean bacterial numbers on surfaces of various equipment in operating rooms, cleaned with disinfectant, were 2.8 c.f.u./10 cm2. Bacterial numbers on surfaces decreased markedly from 253.2 to 11.9 c.f.u./10 cm2 following the use of disinfectant. Bacterial species found from various surfaces were mainly coagulase-negative staphylococci, derived from human beings. In the light of these findings the regular use of disinfectant for cleaning of the floors and other surfaces in operating rooms is advisable. PMID:6512255

  7. Improving the Surface Properties of Inconel 718 BY Applying a CO2 Laser Heat Treatment to a High-Velocity Oxy-Fuel Coating of WC-CrCo Powder

    Science.gov (United States)

    Cho, T. Y.; Yoon, J. H.; Joo, Y. K.; Zhang, S. H.; Cho, J. Y.; Kang, J. H.; Chun, H. G.; Kwon, S. C.; Li, Ming-Xi

    A micron-sized WC-CrCo powder was coated onto an IN718 substrate using high-velocity oxy-fuel (HVOF) thermal spraying. To further improve the surface properties, the HVOF coating was heat-treated by a CO2 laser. The surface properties of both the coating and the laser-heated coating were then compared. The HVOF optimal coating process (OCP) for a coating with the highest surface hardness was determined with the Taguchi program. The friction and wear behaviors of the coating, an electrolytic hard chrome (EHC)-plated coating and IN718, were comparatively investigated via a reciprocating sliding wear test at both 25 and 450°C. The friction coefficient (FC) for all three samples decreased when the sliding surface temperature increased from 25 to 450°C. The FC of the coating decreased with increasing surface temperature: 0.33 ± 0.02 at 25°C to 0.26 ± 0.02 at 450°C the coating had the lowest FC among the three samples. At both temperatures, the coating wear depth (WD) was smaller than those of the EHC sample and IN718. At room temperature, WC-CrCo and the EHC coatings had good wear resistance and had only a shallow WD. IN718, however, had poor wear resistance with 50 μm deep grooves created from fretting corrosion that arose during the 1500 reciprocating slides (2.5 Hz, 10 min sliding wear test). At 450°C, the coating WDs were much shallower than those for the EHC coating and IN718: 0.5-μm deep grooves compared to 60-70-μm deep grooves. These results proved that the coating provided a protective coating for IN718 and other metal components. With the OCP coating fabricated from the powders on the IN718 surface, the surface hardness increased 316% from 399 Hv to 1260 Hv. Furthermore, by laser heating the coating surface for 0.6 s, the hardness increased 44% from 1260 ±30 Hv to 1820 ±100 Hv, porosity decreased more than five times from 2.2 ± 0.3% to 0.4 ± 0.1%, and the coating thickness decreased 17% from 300 to 250 μm. These results showed that both the WC

  8. Insights into seasonal active layer dynamics by monitoring relative velocity changes using ambient seismic noise

    Science.gov (United States)

    James, S. R.; Knox, H. A.; Cole, C. J.; Abbott, R. E.; Screaton, E.

    2016-12-01

    Seasonal freeze and thaw of the active layer above permafrost results in dramatic changes in seismic velocity. We used daily cross correlations of ambient seismic noise recorded at Poker Flat Research Range in central Alaska to create a nearly continuous 2-year record of relative velocity changes. This analysis required that we modify the Moving Window Cross-spectral Analysis technique used in the Python package MSNoise to reduce the occurrence of cycle skipping. Results show relative velocity variations follow a seasonal pattern, where velocities decrease in late spring through the summer months and increase through the fall and winter months. This timing is consistent with active layer freeze and thaw in this region. These results were compared to a suite of ground- and satellite-based measurements to identify relationships. A decrease in relative velocities in late spring closely follows the timing of snow melt recorded in nearby ground temperatures and snow-depth logs. This transition also aligns with a decrease in the Normalized Difference Snow Index (NDSI) derived from multi-temporal Landsat 8 satellite imagery collected over the study site. A gradual increase in relative velocity through the fall months occurs when temperatures below ground surface remain near zero. We suggest this is due to latent heat feedbacks that keep temperatures constant while active layer velocities increase from continued ice formation. This highlights the value in velocity variations for capturing details on the freezing process. In addition, spatial variations in the magnitude of velocity changes are consistent with thaw probe surveys. Exploring relationships with remote sensing may allow indirect measurements of thaw over larger areas and further surface wave analysis may allow for thickness evolution measurements. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for

  9. Microplastics Baseline Surveys at the Water Surface and in Sediments of the North-East Atlantic

    NARCIS (Netherlands)

    Maes, Thomas; van der Meulen, Myra; Devriese, Lisa; Leslie, H.A.; Huvet, Arnaud; Frère, Laura; Robbens, Johan; Vethaak, A.D.

    2017-01-01

    Microplastic contamination was determined in sediments of the Southern North Sea and floating at the sea surface of NorthWest Europe. Floating concentrations ranged between 0 and 1.5 microplastic/m3, whereas microplastic concentrations in sediments ranged between 0 and 3,146 particles/kg dry weight

  10. A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

    Science.gov (United States)

    Wallett, Thomas M.

    2009-01-01

    This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

  11. Survey of shell egg processing plant sanitation programs: effects on non-egg-contact surfaces.

    Science.gov (United States)

    Musgrove, M T; Jones, D R; Northcutt, J K; Curtis, P A; Anderson, K E; Fletcher, D L; Cox, N A

    2004-12-01

    To successfully implement a hazard analysis critical control point plan, prerequisite programs are essential. Sanitation standard operating procedures are an important part of such a plan and can reduce contamination levels so that food safety and quality are not adversely affected. Noncontact surfaces in the shell egg processing plants can serve as a reservoir of cross-contamination. The objective of this study was to assess the efficacy of sanitation programs used in a variety of shell egg processing facilities (in-line, off-line, and mixed operations). Fourteen different noncontact surfaces were sampled in nine commercial facilities across the southeastern United States. Non-egg-contact surfaces were defined as those where the shell egg does not come into direct contact with the surface or with the fluid from that surface. Gauze pads soaked in sterile phosphate-buffered saline were used for sampling at the end of a processing day (POST) and again the next morning prior to operations (PRE). Aerobic plate counts (APCs) and numbers of Enterobacteriaceae were determined. No significant differences (P > 0.05) were found between POST and PRE counts for either population recovered from the 14 sampling sites. Only samples from the floor under the farm belts, nest-run loader, washers, and packer heads were reduced by 1 log CFU/ml of rinsate for APCs or Enterobacteriaceae counts. APCs of more than 10(4) CFU/ml of rinsate were recovered from many samples. Highest APCs were found on the floor under the farm belt and on shelves of the nest-run carts. High APCs were found on the wheel surface for off-line carts and on the loading dock floor. Highest Enterobacteriaceae counts were found in samples from the floor, drain, and nest-run egg cart shelves. A lack of significant difference between POST and PRE counts indicates that current sanitation programs could be improved. These data suggest that traffic patterns for the movement of eggs and materials through the plant should be

  12. Blind comparisons of shear-wave velocities at closely-spaced sites in San Jose, California: Proceedings of a Workshop held at the US Geological Survey, Menlo Park, May 3, 2004

    Science.gov (United States)

    Asten, Michael W.; Boore, David M.

    2005-01-01

    Shear-wave velocities within several hundred meters of Earth's surface are important in specifying earthquake ground motions for engineering design. Not only are the shearwave velocities used in classifying sites for use of modern building codes, but they are also used in site-specific studies of particularly significant structures. Many are the methods for estimating sub-surface shear-wave velocities, but few are the blind comparisons of a number of the methods at a single site. The word "blind" is important here and means that the measurements and interpretations are done completely independent of one another. Stephen Hartzell of the USGS office on Golden, Colorado realized that such an experiment would be very useful for assessing the strengths and weaknesses of the various methods, and he and Jack Boatwright of the USGS office in Menlo Park, California, in cooperation with Carl Wentworth of the Menlo Park USGS office found a convenient site in the city of San Jose, California. The site had good access and space for conducting experiments, and a borehole drilled to several hundred meters by the Santa Clara Valley Water District was made available for downhole logging. Jack Boatwright asked David Boore to coordinate the experiment. In turn, David Boore persuaded several teams to make measurements, helped with the local logistics, collected the results, and organized and conducted an International Workshop in May, 2004. At this meeting the participants in the experiment gathered in Menlo Park to describe their measurements and interpretations, and to see the results of the comparisons of the various methods for the first time. This Open-File Report describes the results of that workshop. One of the participants, Michael Asten, offered to help the coordinator prepare this report. Because of his lead role in pulling the report together, Dr. Asten is the lead author of the paper to follow and is also the lead Compiler for the Open-File Report.It is important to

  13. Breast and ovarian cancers: a survey and possible roles for the cell surface heparan sulfate proteoglycans

    DEFF Research Database (Denmark)

    Yoneda, Atsuko; Lendorf, Maria E; Couchman, John R

    2012-01-01

    of breast cancer may also develop ovarian cancer. Here, the authors review the different tumor markers of breast and ovarian carcinoma and discuss the expression, mutations, and possible roles of cell surface heparan sulfate proteoglycans during tumorigenesis of these carcinomas. The focus is on two groups...... of proteoglycans, the transmembrane syndecans and the lipid-anchored glypicans. Both families of proteoglycans have been implicated in cellular responses to growth factors and morphogens, including many now associated with tumor progression....

  14. Survey of Techniques for Deep Web Source Selection and Surfacing the Hidden Web Content

    OpenAIRE

    Khushboo Khurana; M.B. Chandak

    2016-01-01

    Large and continuously growing dynamic web content has created new opportunities for large-scale data analysis in the recent years. There is huge amount of information that the traditional web crawlers cannot access, since they use link analysis technique by which only the surface web can be accessed. Traditional search engine crawlers require the web pages to be linked to other pages via hyperlinks causing large amount of web data to be hidden from the crawlers. Enormous data is available in...

  15. Network global navigation satellite system survey to harmonize water-surface elevation data for the Rainy River Basin

    Science.gov (United States)

    Ziegeweid, Jeffrey R.; Silliker, R. Jason; Densmore, Brenda K.; Krahulik, Justin

    2016-08-15

    Continuously recording water-level streamgages in Rainy Lake and Namakan Reservoir are used to regulate water levels according to rule curves established in 2000 by the International Joint Commission; however, water levels at streamgages were referenced to a variety of vertical datums, confounding efforts to model the flow of water through the system, regulate water levels during periods of high inflow, and evaluate the effectiveness of the rule curves. In October 2014, the U.S. Geological Survey, Natural Resources Canada, International Joint Commission, and National Park Service began a joint field study with the goal of obtaining precise elevations referenced to a uniform vertical datum for all reference marks used to set water levels at streamgages throughout Rainy Lake and Namakan Reservoir. This report was prepared by the U.S. Geological Survey in cooperation with Natural Resources Canada, International Joint Commission, and National Park Service.Three field crews deployed Global Navigation Satellite System receivers statically over 16 reference marks colocated with active and discontinued water-level streamgages throughout Rainy River, Rainy Lake, Namakan Reservoir, and select tributaries of Rainy Lake and Namakan Reservoir. A Global Navigation Satellite System receiver also was deployed statically over a National Geodetic Survey cooperative base network control station for use as a quality-control reference mark. Satellite data were collected simultaneously during a 5-day period and processed independently by the U.S. Geological Survey and Natural Resources Canada to obtain accurate positioning and elevations for the 17 surveyed reference marks. Processed satellite data were used to convert published water levels to elevations above sea level referenced to the Canadian Geodetic Vertical Datum of 2013 in order to compare water-surface elevations referenced to a uniform vertical datum throughout the study area. In this report, an “offset” refers to the

  16. High-Velocity Clouds

    NARCIS (Netherlands)

    Wakker, Bart P.; Woerden, Hugo van; Oswalt, Terry D.; Gilmore, Gerard

    2013-01-01

    The high-velocity clouds (HVCs) are gaseous objects that do not partake in differential galactic rotation, but instead have anomalous velocities. They trace energetic processes on the interface between the interstellar material in the Galactic disk and intergalactic space. Three different processes

  17. Using public participation to sample trace metals in lake surface sediments: the OPAL Metals Survey.

    Science.gov (United States)

    Turner, S D; Rose, N L; Goldsmith, B; Bearcock, J M; Scheib, C; Yang, H

    2017-05-01

    Members of the public in England were invited in 2010 to take part in a national metals survey, by collecting samples of littoral sediment from a standing water body for geochemical analysis. To our knowledge, this is the first national sediment metals survey using public participation and reveals a snapshot of the extent of metals contamination in ponds and lakes across England. Hg, Ni, Cu, Zn and Pb concentrations exceeding sediment quality guidelines for the health of aquatic biota are ubiquitous in ponds and lakes, not just in areas with a legacy of industrial activity. To validate the public sampling approach, a calibration exercise was conducted at ten water bodies selected to represent a range of lakes found across England. Sediment concentrations of Hg, Ni, Cu, Zn and Pb were measured in samples of soil, stream and littoral and deep water sediment to assess inputs. Significant differences between littoral sediment metal concentrations occur due to local variability, but also organic content, especially in upland, peat soil catchments. Variability of metal concentrations between littoral samples is shown to be low in small (complex inputs and variation in organic content of littoral samples have a greater variability. Collection of littoral sediments in small lakes and ponds, with or without voluntary participation, can provide a reliable sampling technique for the preliminary assessment of metal contamination in standing waters. However, the heterogeneity of geology, soils and history/extent of metal contamination in the English landscape, combined with the random nature of sample collection, shows that systematic sampling for evaluating the full extent of metal contamination in lakes is still required.

  18. Study on the interaction between a grid-generated turbulence and a circular cylinder. Influence of the main stream turbulence on the wake-induced velocity field and the pressure fluctuations on the cylinder surface; Koshi ranryu to enchu no kansho ni kansuru kenkyu. Shuru midare no koryu yudo sokudoba to enchu hyomen atsuryokuba eno eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Y.; Sakai, M.; Kushida, T.; Nakamura, I. [Nagoya University, Nagoya (Japan)

    1999-08-25

    The interaction between the grid-generated turbulent flow and a 2-dimensional circular cylinder is investigated experimentally. Particular attention has been devoted to the effect of the main stream turbulence (intensity and scale of the turbulence) on the wake-induced velocity field in the upstream region and the pressure fluctuation on the cylinder surface. The velocity in the upstream region and the pressure on the cylinder surface have been measured simultaneously with the velocity in the near wake, using the I-type hot-wire probes and the pressure transducer. The velocity signals measured in the upstream region and the pressure signals on the cylinder surface are analyzed by the phase average technique on the basis of the reference band-passed velocity signals in the near wake. It is found that in the case that the intensity of main stream turbulence is large and the rate of the scale of turbulence to the cylinder diameter is small, the upstream region where the periodic velocity fluctuations appear becomes large. In this case, the fluctuation of the lift force is also large. (author)

  19. Bacterial contamination of floors and other surfaces in operating rooms: a five-year survey.

    OpenAIRE

    Suzuki, A.; Namba, Y; Matsuura, M; Horisawa, A.

    1984-01-01

    Bacterial contamination of floors and other surfaces in the operating suite has been investigated by contact impression plates during the past five years. Colony counts of the floors of operating rooms, cleaned with disinfectant, were 3.3 c.f.u./10 cm2; on the floors of semi-clean and dirty areas, cleaned with detergent, colony counts were 44.8 and 71.4 c.f.u./10 cm2 respectively. The highest colony counts of 487.4 c.f.u./10 cm2 were found in the dressing rooms, the floors of which were cover...

  20. Imaging near-surface heterogeneities by natural migration of surface waves

    KAUST Repository

    Liu, Zhaolun

    2016-09-06

    We demonstrate that near-surface heterogeneities can be imaged by natural migration of backscattered surface waves in common shot gathers. No velocity model is required because the data are migrated onto surface points with the virtual Green\\'s functions computed from the shot gathers. Migrating shot gathers recorded by 2D and 3D land surveys validates the effectiveness of detecting nearsurface heterogeneities by natural migration. The implication is that more accurate hazard maps can be created by migrating surface waves in land surveys.

  1. A prospective survey of air and surface fungal contamination in a medical mycology laboratory at a tertiary care university hospital.

    Science.gov (United States)

    Sautour, Marc; Dalle, Frédéric; Olivieri, Claire; L'ollivier, Coralie; Enderlin, Emilie; Salome, Elsa; Chovelon, Isabelle; Vagner, Odile; Sixt, Nathalie; Fricker-Pap, Véronique; Aho, Serge; Fontaneau, Olivier; Cachia, Claire; Bonnin, Alain

    2009-04-01

    Invasive filamentous fungi infections resulting from inhalation of mold conidia pose a major threat in immunocompromised patients. The diagnosis is based on direct smears, cultural symptoms, and culturing fungi. Airborne conidia present in the laboratory environment may cause contamination of cultures, resulting in false-positive diagnosis. Baseline values of fungal contamination in a clinical mycology laboratory have not been determined to date. A 1-year prospective survey of air and surface contamination was conducted in a clinical mycology laboratory during a period when large construction projects were being conducted in the hospital. Air was sampled with a portable air system impactor, and surfaces were sampled with contact Sabouraud agar plates. The collected data allowed the elaboration of Shewhart graphic charts. Mean fungal loads ranged from 2.27 to 4.36 colony forming units (cfu)/m(3) in air and from 0.61 to 1.69 cfu/plate on surfaces. Strict control procedures may limit the level of fungal contamination in a clinical mycology laboratory even in the context of large construction projects at the hospital site. Our data and the resulting Shewhart graphic charts provide baseline values to use when monitoring for inappropriate variations of the fungal contamination in a mycology laboratory as part of a quality assurance program. This is critical to the appropriate management of the fungal risk in hematology, cancer and transplantation patients.

  2. Reprocessing of seismic reflection data using a macro velocity model independent imaging method - New insight into the crustal structure of northern Germany from Common Reflection Surface stack (CRS) sections.

    Science.gov (United States)

    Yoon, M.; Baykulov, M.; Duemmong, S.; Brink, H. J.; Gajewski, D.

    2006-12-01

    In this paper we present new seismic images of the North German Basin that resulted from intensive reprocessing of industrial seismic reflection data. The data sets were already acquired and processed in the early 80ies. The main focus was set on the sedimentary fill of the basin. During reprocessing the focus was moved to lower crustal structures in order to investigate the influence of old deep rooted processes on the evolution of the Central European Basin System (CEBS). During reprocessing the Common Reflection Surface (CRS) stack method was applied. This method is an entirely data-oriented approach which is macro velocity model independent (Mueller et al., 1998; Mueller, 1998). It has already been successfully applied to reflection data from sedimentary basins (Trappe et al., 2001; Menyoli, 2004), but yet it was not used to investigate the crystalline crust and deeper structures. In the reprocessed time sections the image quality of the lower and middle crust as well as the visibility of the Moho could be significantly improved. The latter appears as a flat reflection band contrary to former results where an east dipping Moho was observed. The flat Moho is in conflict with the currently supported extension model of the Glueckstadt Graben. However, the flat Moho topography would be in good agreement with other observations from the CEBS, e.g. DEKORP profiles (DEKORP-BASIN Research Group, 1999) or the Dniepr-Donets basin, Ukraine (Maystrenko et al., 2003). Furthermore, multiples could be succesfully suppressed using a macro velocity model as apriori information during iterative CRS stack procedure. The presented real data examples show that the CRS stack method provides a promising tool for imaging crustal and subcrustal features as well as for multiple suppression.

  3. Differential efficiencies of dip-net sampling versus sampling surface-floating pupal exuviae in a biodiversity survey of Chironomidae

    Directory of Open Access Journals (Sweden)

    Leonard Charles Ferrington Jr

    2014-12-01

    Full Text Available Relative efficiencies of standard dip-net sampling (SDN versus collections of surface-floating pupal exuviae (SFPE were determined for detecting Chironomidae at catchment and site scales and at subfamily/tribe-, genus- and species-levels based on simultaneous, equal-effort sampling on a monthly basis for one year during a biodiversity assessment of Bear Run Nature Reserve. Results showed SFPE was more efficient than SDN at catchment scales for detecting both genera and species. At site scales, SDN sampling was more efficient for assessment of a first-order site. No consistent pattern, except for better efficiency of SFPE to detect Orthocladiinae genera, was observed at genus-level for two second-order sites. However, SFPE was consistently more efficient at detecting species of Orthocladiinae, Chironomini and Tanytarsini at the second order sites. SFPE was more efficient at detecting both genera and species at two third-order sites. The differential efficiencies of the two methods are concluded to be related to stream order and size, substrate size, flow and water velocity, depth and habitat heterogeneity, and differential ability to discriminate species among pupal exuviae specimens versus larval specimens. Although both approaches are considered necessary for comprehensive biodiversity assessments of Chironomidae, our results suggest that there is an optimal, but different, allocation of sampling effort for detecting Chironomidae across stream orders and at differing spatial and taxonomic scales.Article submitted 13. August 2014, accepted 31. October 2014, published 22. December 2014.

  4. Gemini NIFS survey of feeding and feedback processes in nearby active galaxies - II. The sample and surface mass density profiles

    Science.gov (United States)

    Riffel, R. A.; Storchi-Bergmann, T.; Riffel, R.; Davies, R.; Bianchin, M.; Diniz, M. R.; Schönell, A. J.; Burtscher, L.; Crenshaw, M.; Fischer, T. C.; Dahmer-Hahn, L. G.; Dametto, N. Z.; Rosario, D.

    2018-02-01

    We present and characterize a sample of 20 nearby Seyfert galaxies selected for having BAT 14-195 keV luminosities LX ≥ 1041.5 erg s-1, redshift z ≤ 0.015, being accessible for observations with the Gemini Near-Infrared Field Spectrograph (NIFS) and showing extended [O III]λ5007 emission. Our goal is to study Active Galactic Nucleus (AGN) feeding and feedback processes from near-infrared integral-field spectra, which include both ionized (H II) and hot molecular (H2) emission. This sample is complemented by other nine Seyfert galaxies previously observed with NIFS. We show that the host galaxy properties (absolute magnitudes MB, MH, central stellar velocity dispersion and axial ratio) show a similar distribution to those of the 69 BAT AGN. For the 20 galaxies already observed, we present surface mass density (Σ) profiles for H II and H2 in their inner ˜500 pc, showing that H II emission presents a steeper radial gradient than H2. This can be attributed to the different excitation mechanisms: ionization by AGN radiation for H II and heating by X-rays for H2. The mean surface mass densities are in the range (0.2 ≤ ΣH II ≤ 35.9) M⊙ pc-2, and (0.2 ≤ ΣH2 ≤ 13.9)× 10-3 M⊙ pc-2, while the ratios between the H II and H2 masses range between ˜200 and 8000. The sample presented here will be used in future papers to map AGN gas excitation and kinematics, providing a census of the mass inflow and outflow rates and power as well as their relation with the AGN luminosity.

  5. Northern dwarf and low surface brightness galaxies. II - The Green Bank neutral hydrogen survey

    Science.gov (United States)

    Schneider, Stephen E.; Thuan, Trinh X.; Mangum, Jeffrey G.; Miller, John

    1992-01-01

    The paper reports neutral hydrogen observations of a large sample of dwarf and other low surface brightness galaxies. A detailed discussion and error analysis of the observations are presented, and spectra are displayed for 329 galaxies detected for the first time, or detected with substantially better signal-to-noise ratios than achieved previously. The positions on the sky of 667 galaxies meeting the present selection criteria north of delta = 38 deg are shown. The distribution of the redshifts of galaxies detected at Green Bank is illustrated. The Green Bank detections tapered off strongly below the median H I flux of 3.7 Jy km/s detected at Arecibo: only 12 percent of the Green Bank sample was detected with smaller fluxes.

  6. Probability Density Functions and Higher Order Statistics of Large-Scale Geostrophic Velocity Estimates and Sea Surface Height, as seen from the Jason-1 -TOPEX/Poseidon Tandem Mission

    Science.gov (United States)

    Scharffenberg, Martin G.; Biri, Stavroula; Stammer, Detlef

    2013-09-01

    Geostrophic velocity Probability Density Functions (PDF), Skewness (S) and Kurtosis (K) are shown for both velocity components (u, v) estimated from the 3- year long Jason-1 - TOPEX/Poseidon (JTP) Tandem Mission which allowed infer both velocity components directly from the altimeter observations. To be comparable to previous results of velocity- (w) and SSH-PDF, we include the 18.5-year time series of SSH from the TOPEX/Poseidon, Jason-1 and Jason-2 (TPJJ) missions.The differences in the PDF of both velocity components are found to be evident, with a wider shape for the zonal velocity component due to the larger variability in zonal direction. Results confirm that the exponential shape of the global velocity PDF is a consequence of the spatially inhomogeneous EKE distribution over the global ocean. Only regions with a small variance in EKE, have Gaussian shaped PDF, however, normalizing each time series with their STD results in Gaussian PDF everywhere.

  7. Survey of Permafrost Thaw Influence on Surface Water Dissolved Organic Matter in Sub-Arctic Alaska

    Science.gov (United States)

    Gagne, K.; Walter Anthony, K. M.; Guerard, J.

    2016-12-01

    The chemical and functional group composition of permafrost organic matter largely remains unknown. Characterizing dissolved organic matter (DOM) chemical composition offers insight into the quality and extent of the permafrost carbon pool that may mobilize and transform into smaller components or greenhouse gasses upon thaw. The Goldstream watershed in interior Alaska is underlain by discontinuous permafrost with varying stage of talik (thaw bulb) development, allowing for the comparison of thaw stage on DOM composition. Surface water samples were collected from lakes and streams in regions of the watershed with varying degrees of permafrost thaw in order to investigate seasonal variability and associated trends in DOM composition. Additionally, select permafrost cores were obtained and utilized in leachate experiments to identify the fraction and reactivity of the soil organic carbon pool leached from active layer and permafrost soil upon thaw. Leached organic moieties were compared to the total permafrost organic carbon pool and the DOM of the overlying surface water. Extracted isolates from both permafrost and active layer were characterized by 3D excitation-emission fluorescence, UV-vis spectroscopy, PARAFAC, SPR-W5-WATERGATE 1H- NMR, total organic carbon, ICP-MS, and ion chromatography, coupled with photolysis experiments to determine reactive oxygen species production to characterize potential reactivity. Differences in carbon pool composition were resolved between seasons and with the extent of permafrost thaw. This is a key first step to determine how permafrost degradation influences DOM pool composition on a molecular level, which is essential for assessing permafrost organic matter impact on biogeochemical cycling and other ecological functions as it becomes incorporated into a warming landscape.

  8. Surface creep and slip-behavior segmentation along the northwestern Xianshuihe fault zone of southwestern China determined from decades of fault-crossing short-baseline and short-level surveys

    Science.gov (United States)

    Zhang, Jing; Wen, Xue-ze; Cao, Jian-ling; Yan, Wei; Yang, Yong-lin; Su, Qin

    2018-01-01

    This study examines the 200-km-long northwestern Xianshuihe fault zone (NWXFZ), southwestern China, using more than three decades of geodetic observations from fault-crossing short-baseline and short-leveling surveys at seven sites. These data enable estimates of creep rates and depths, and examination of the long-term slip behavior. The surface motion of the NWXFZ is dominated by sinistral creep, although sinistral, transverse, and vertical slip components show spatio-temporal variations. Combining these slip variations with data of earthquake rupture, coseismic slip, seismicity, fault geometry, and far-fault movement velocity, and using the velocity-and-state friction theory, our analysis indicates that the surface slip behavior of the NWXFZ is segmented along strike. The 1973 rupture section of this fault zone exhibits spatio-temporally variable slip behavior, showing time-decaying post-1973 afterslip on the northwestern and southeastern parts of the rupture at depths above 5.8 - 7.0 km with average sinistral-creep rates of 1.3 and 3.5 mm/yr, respectively, but being relocked in the central part of the rupture. The 1923/1981 rupture section is generally in locking state, with postseismic and interseismic sinistral-creep at 1.1 mm/yr on its central part at depths above 2.0-2.8 km. The 1893 rupture section has been tightly locked without creep since at least the early 1980s. The thickness of the shallow velocity-strengthening (or creep) layer and the restraining bend geometry of the NWXFZ are the key factors that control spatio-temporal variations in surface creep rates. Two surface-observed locked fault portions are located within two different restraining bends in the NWXFZ, both of which act as compressive asperities and hence have enabled the long-term locking of these portions. Creep along the NWXFZ has also been affected to varying degrees by M6.5 - Mw9.2 earthquakes at distances of 50 - 3800 km from the fault zone. Most of these effects have been removed

  9. Visual surveying platform for the automated detection of road surface distresses

    Science.gov (United States)

    Naidoo, Thegaran; Joubert, Deon; Chiwewe, Tapiwa; Tyatyantsi, Ayanda; Rancati, Bruno; Mbizeni, Asanda

    2014-06-01

    Road distresses, such as potholes and edge cracks, are not only a source of frustration to drivers but also negatively impact the economy due to damage to motor vehicles and costly ro6ad repairs. Regular and rapid pavement inspection and maintenance is vital to preventing pothole formation and growth. To improve the efficiency of maintenance and reduce the cost thereof, the Visual Surveying Platform (VSP) is being developed that will automatically detect and analyse road distresses. The VSP consists of a vehicle mounted sensor system, consisting of a high speed camera and a Global Positioning System (GPS) receiver, and an analysis and visualization software suite. The system extracts both a visual image and the coordinates of a detected road defect from recorded video and presents it in an interactive interface for use by technical experts and maintenance schedulers. The VSP automatically detects and classifies road distresses using a two-stage artificial neural network framework. Video frames first undergo hue, saturation and value (HSV) colour space conversion as well as a spatial frequency transformation before being used as inputs to the neural networks. A road detector neural network first classifies which section of the image contains the road, after which a distress detector neural network identifies those road regions containing defects. Although the VSP can be adapted to detect any type of road distress it has been trained to specifically detect potholes. An initial prototype of the VSP was designed and constructed. The prototype was also trained and tested on real-world data collected from provincial roads.

  10. Augmenting two-dimensional hydrodynamic simulations with measured velocity data to identify flow paths as a function of depth on Upper St. Clair River in the Great Lakes basin

    Science.gov (United States)

    Holtschlag, D.J.; Koschik, J.A.

    2005-01-01

    Upper St. Clair River, which receives outflow from Lake Huron, is characterized by flow velocities that exceed 7 feet per second and significant channel curvature that creates complex flow patterns downstream from the Blue Water Bridge in the Port Huron, Michigan, and Sarnia, Ontario, area. Discrepancies were detected between depth-averaged velocities previously simulated by a two-dimensional (2D) hydrodynamic model and surface velocities determined from drifting buoy deployments. A detailed ADCP (acoustic Doppler current profiler) survey was done on Upper St. Clair River during July 1–3, 2003, to help resolve these discrepancies. As part of this study, a refined finite-element mesh of the hydrodynamic model used to identify source areas to public water intakes was developed for Upper St. Clair River. In addition, a numerical procedure was used to account for radial accelerations, which cause secondary flow patterns near channel bends. The refined model was recalibrated to better reproduce local velocities measured in the ADCP survey. ADCP data also were used to help resolve the remaining discrepancies between simulated and measured velocities and to describe variations in velocity with depth. Velocity data from ADCP surveys have significant local variability, and statistical processing is needed to compute reliable point estimates. In this study, velocity innovations were computed for seven depth layers posited within the river as the differences between measured and simulated velocities. For each layer, the spatial correlation of velocity innovations was characterized by use of variogram analysis. Results were used with kriging to compute expected innovations within each layer at applicable model nodes. Expected innovations were added to simulated velocities to form integrated velocities, which were used with reverse particle tracking to identify the expected flow path near a sewage outfall as a function of flow depth. Expected particle paths generated by use

  11. NEAR-SURFACE SEISMIC VELOCITY DATA: A ...

    African Journals Online (AJOL)

    114 ~124. Slotnick, M. M. (1959): Lessons in Seismic. Computing. The Society of. Exploration Geophysicists, Tulsa,. Oklahoma. Spiegel, M. R. (1992): Theory and Problems of Statistics, 2nd Revised Ed. S.I.Ed. (Schaum's Outline Series), McGraw-. Hill Book Co., London. ' Uko, E. D., Ekine, A. S., Ebeniro, J. 0., and. Ofoegbu.

  12. Antarctic Ice Velocity Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This compilation of recent ice velocity data of the Antarctic ice sheet is intended for use by the polar scientific community. The data are presented in tabular form...

  13. Boat-based river bathymetry and stream velocity on the upper Willamette River, Oregon, Spring 2015

    Science.gov (United States)

    Lind, Greg D.; Wellman, Roy E.; Mangano, Joseph F.

    2017-01-01

    River bathymetry and stream velocity measurements were collected in March 2015 along the upper Willamette River, Oregon, between Eugene and Corvallis. These surveys were collected over a small range of discharges using a real time kinematic global positioning system (RTK-GPS) and acoustic Doppler current profiler (ADCP) on a motorboat while transecting at various cross sections along the river. These datasets were collected for equipment calibration and validation for the National Aeronautics and Space Administration’s (NASA) Surface Water and Ocean Topography (SWOT) satellite mission. This is one of multiple survey datasets that will be released for this effort.

  14. Hepatitis B surface antigen prevalence in pregnant women: A cross-sectional survey in Iran.

    Science.gov (United States)

    Shoghli, Alireza; Nabavi, Seyed Mahmood; Alavian, Seyed Moayed; Kolifarhood, Goodarz; Goya, Mohammad Mehdi; Namazi, Roshanak; Fallahnezhad, Mojtaba; Mohajeri, Mansor; Mousavinasab, Nouraldin; Zanjani, Rahim Sorouri; Saeini, Mohammad Reza; Jalilvand, Ahmad

    2014-12-01

    Vertical transmission of hepatitis B virus (HBV) from infected mothers to their neonates is one of the most important routes of infection. The exact prevalence rate of HBV in Iranian pregnant mothers is not well known but based on different studies it is estimated between 0.35% and 6.5%. The aim of this study was to determine the seroprevalence of hepatitis B surface antigen (HBsAg) in pregnant women of selected provinces in Iran. At this cross-sectional study, seven provinces supposed to be of high and low prevalence of hepatitis B in the general population selected. Multistage sampling was used to enroll 5261 parturient women who attended the target provinces birth facilities, during January to March of 2011, were recruited to study. To determine the statistically significant mean and proportion differences, t-test and χ (2) test were used, respectively. Overall 1.2% was positive HBsAg of which 11% of them were hepatitis B e-antigen positive as well. The eastern and north eastern provinces were considerably higher in HBsAg seropositivity than the west and northwest of the country. In view of the considerable prevalence of hepatitis B in pregnant women, screening all pregnant women prioritizing the eastern and north-eastern provinces is strongly recommended.

  15. Insights into the Structure and Surface Geology of Isla Socorro, Mexico, from Airborne Magnetic and Gamma-Ray Surveys

    Science.gov (United States)

    Paoletti, V.; Gruber, S.; Varley, N.; D'Antonio, M.; Supper, R.; Motschka, K.

    2016-05-01

    The island of Socorro is located in the eastern Pacific Ocean, 650 km off the coast of Mexico. It is a rare example of an oceanic volcanic island whose above sea level volume is made up mostly of peralkaline trachytes and rhyolites, with subordinate mafic rocks. Subaerial volcanism started several hundred thousand years ago and continues until recent times. We present an investigation of surface and subsurface geology of the island, based on the first detailed extensive geophysical survey on the island. Acquired airborne magnetic and gamma-ray data were compared to existing geological information and supplemented with field investigations and satellite imagery. Magnetic data show a wide minimum in the central part of the island, possibly connected to a high-temperature zone in the deeper central portion of the volcano, likely to be due to a still hot magma body. The data also depict two parallel edges possibly suggesting the existence of a nested caldera. Analysis on upward continued magnetic data by recent imaging techniques highlighted two deep sources located around 5 km b.s.l., interpreted as feeding structures that are now filled with crystalline rocks. Gamma-ray data have been interpreted through integration with the geological survey results. Several previously known volcanic deposits have been identified based on radioelement distribution, and others have been redefined based on field evidence. A new succession of volcanic members is proposed, to be verified through more detailed geological mapping, geochemical analyses of rock samples and radiometric dating.

  16. Repeat Surveys to Evaluate Seasonal Variability in Seafloor and Shallow Sub-surface Acoustic Properties, Shallow Water Gulf of Mexico

    Science.gov (United States)

    2008-01-01

    using 1500 m/s as a velocity) and shows a consistent unconformity separating the youngest sediment cover from older deposits. The depth below seafloor...of the identified unconformity ranges from 4 to 8 m (using velocity of 1500 m/s). Two coring programs (March-April 2008) were conducted in

  17. Transverse spectral velocity estimation.

    Science.gov (United States)

    Jensen, Jørgen

    2014-11-01

    A transverse oscillation (TO)-based method for calculating the velocity spectrum for fully transverse flow is described. Current methods yield the mean velocity at one position, whereas the new method reveals the transverse velocity spectrum as a function of time at one spatial location. A convex array probe is used along with two different estimators based on the correlation of the received signal. They can estimate the velocity spectrum as a function of time as for ordinary spectrograms, but they also work at a beam-to-flow angle of 90°. The approach is validated using simulations of pulsatile flow using the Womersly-Evans flow model. The relative bias of the mean estimated frequency is 13.6% and the mean relative standard deviation is 14.3% at 90°, where a traditional estimator yields zero velocity. Measurements have been conducted with an experimental scanner and a convex array transducer. A pump generated artificial femoral and carotid artery flow in the phantom. The estimated spectra degrade when the angle is different from 90°, but are usable down to 60° to 70°. Below this angle the traditional spectrum is best and should be used. The conventional approach can automatically be corrected for angles from 0° to 70° to give fully quantitative velocity spectra without operator intervention.

  18. The ATLAS3D project - XXI. Correlations between gradients of local escape velocity and stellar populations in early-type galaxies

    NARCIS (Netherlands)

    Scott, Nicholas; Cappellari, Michele; Davies, Roger L.; Kleijn, Gijs Verdoes; Bois, Maxime; Alatalo, Katherine; Blitz, Leo; Bournaud, Frédéric; Bureau, Martin; Crocker, Alison; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M.

    We explore the connection between the local escape velocity, Vesc, and the stellar population properties in the ATLAS3D survey, a complete, volume-limited sample of nearby early-type galaxies. We make use of ugriz photometry to construct Multi-Gaussian Expansion models of the surface brightnesses of

  19. The ATLAS(3D) project : XXI. Correlations between gradients of local escape velocity and stellar populations in early-type galaxies

    NARCIS (Netherlands)

    Scott, Nicholas; Cappellari, Michele; Davies, Roger L.; Kleijn, Gijs Verdoes; Bois, Maxime; Alatalo, Katherine; Blitz, Leo; Bournaud, Frederic; Bureau, Martin; Crocker, Alison; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M.; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Serra, Paolo; Weijmans, Anne-Marie; Young, Lisa M.

    2013-01-01

    We explore the connection between the local escape velocity, V-esc, and the stellar population properties in the ATLAS(3D) survey, a complete, volume-limited sample of nearby early-type galaxies. We make use of ugriz photometry to construct Multi-Gaussian Expansion models of the surface brightnesses

  20. RADIAL VELOCITIES OF GALACTIC O-TYPE STARS. II. SINGLE-LINED SPECTROSCOPIC BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Williams, S. J.; Gies, D. R. [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106 (United States); Hillwig, T. C. [Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383 (United States); McSwain, M. V. [Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA 18015 (United States); Huang, W., E-mail: swilliams@chara.gsu.edu, E-mail: gies@chara.gsu.edu, E-mail: todd.hillwig@valpo.edu, E-mail: mcswain@lehigh.edu, E-mail: hwenjin@astro.washington.edu [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States)

    2013-02-01

    We report on new radial velocity measurements of massive stars that are either suspected binaries or lacking prior observations. This is part of a survey to identify and characterize spectroscopic binaries among O-type stars with the goal of comparing the binary fraction of field and runaway stars with those in clusters and associations. We present orbits for HDE 308813, HD 152147, HD 164536, BD-16 Degree-Sign 4826, and HDE 229232, Galactic O-type stars exhibiting single-lined spectroscopic variation. By fitting model spectra to our observed spectra, we obtain estimates for effective temperature, surface gravity, and rotational velocity. We compute orbital periods and velocity semiamplitudes for each system and note the lack of photometric variation for any system. These binaries probably appear single-lined because the companions are faint and because their orbital Doppler shifts are small compared to the width of the rotationally broadened lines of the primary.

  1. Fishery-independent surface abundance and density estimates of swordfish (Xiphias gladius) from aerial surveys in the Central Mediterranean Sea

    Science.gov (United States)

    Lauriano, Giancarlo; Pierantonio, Nino; Kell, Laurence; Cañadas, Ana; Donovan, Gregory; Panigada, Simone

    2017-07-01

    Fishery-independent surface density and abundance estimates for the swordfish were obtained through aerial surveys carried out over a large portion of the Central Mediterranean, implementing distance sampling methodologies. Both design- and model-based abundance and density showed an uneven occurrence of the species throughout the study area, with clusters of higher density occurring near converging fronts, strong thermoclines and/or underwater features. The surface abundance was estimated for the Pelagos Sanctuary for Mediterranean Marine Mammals in the summer of 2009 (n=1152; 95%CI=669.0-1981.0; %CV=27.64), the Sea of Sardinia, the Pelagos Sanctuary and the Central Tyrrhenian Sea for the summer of 2010 (n=3401; 95%CI=2067.0-5596.0; %CV=25.51), and for the Southern Tyrrhenian Sea during the winter months of 2010-2011 (n=1228; 95%CI=578-2605; %CV=38.59). The Mediterranean swordfish stock deserves special attention in light of the heavy fishing pressures. Furthermore, the unreliability of fishery-related data has, to date, hampered our ability to effectively inform long-term conservation in the Mediterranean Region. Considering that the European countries have committed to protect the resources and all the marine-related economic and social dynamics upon which they depend, the information presented here constitute useful data towards the international legal requirements under the Marine Strategy Framework Directory, the Common Fisheries Policy, the Habitats and Species Directive and the Directive on Maritime Spatial Planning, among the others.

  2. High-velocity penetrators

    Science.gov (United States)

    Lundgren, Ronald G.

    This paper summarizes the results of studies, coupled with a series of tests, that investigated rigid-body projectiles (penetrators) at high (up to 5500 ft/sec) velocities. Before these studies, it had been hypothesized that a velocity limit would be reached at which increasing the velocity would not commensurately increase depth of penetration into a target. It was further inferred that a given velocity/ penetration depth curve would avalanche into the hydrodynamic regime; that is, increasing the velocity past a certain point would decrease penetration performance. The test series utilized 1/2-in., 3-in., and 5 1/2-in. diameter, ogive-nose steel projectiles and grout and concrete targets. The tests confirmed that penetration depth increased as striking velocity increased to 4000 ft/sec. However, beyond striking velocities of 4000 ft/sec, asymmetric erosion and indentation of the projectile nose from the aggregate caused the projectile trajectories to deviate severely from the target centerline. These trajectory deviations caused the projectile to exit the side of the target, severely bend, break, or exhibit decreased penetration performance, confirming the hypothesis. Clearly, these results were dependent on the specific material and geometric parameters. The projectiles had 3.0 and 4.25 CRH (Caliber-Radius-Head) nose shapes and were heat-treated to R(sub c) 38-40. The grout targets had a maximum aggregate diameter of 3/16 in. and a nominal unconfined compressive strength of 2.5 ksi. The concrete targets had a maximum aggregate diameter of 3/4 in. and unconfined compressive strength of 5.5 ksi.

  3. Location of sound velocity profiles collected by the U.S. Geological Survey in the nearshore surrounding the Elizabeth Islands, MA (2010-003-FA_SVPs, ESRI point shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS),...

  4. SVPprofile_locs.shp - Location of sound velocity profiles collected by the U.S. Geological Survey in 2007, 2009, and 2011 in Vineyard Sound and Buzzards Bay, MA (Esri point shapefile, Geographic, WGS 84)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS),...

  5. Sound velocity profile locations, images, and processed text collected by the U.S. Geological Survey in the vicinity of Muskeget Channel, MA, 2010 (Geographic, WGS 84, Esri Shapefile, PNG images, and text files)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data were collected in a collaboration between the Woods Hole Oceanographic Institution and the U.S. Geological Survey (USGS). The primary objective of this...

  6. Preliminary Investigation of Paleochannels and Groundwater Specific Conductance using Direct-Current Resistivity and Surface-Wave Seismic Geophysical Surveys at the Standard Chlorine of Delaware, Inc., Superfund Site, Delaware City, Delaware, 2008

    Science.gov (United States)

    Degnan, James R.; Brayton, Michael J.

    2010-01-01

    material stiffness; clays and cemented sediments will have a higher velocity than silts, sands, and gravels (in order of increasing hydraulic conductivity). Geophysical surveys detected elevated SC associated with contamination of the surficial Columbia aquifer. Groundwater with elevated SC over ambient (by an order of magnitude) produced a decrease in measured resistivity at the SCD site. Where SC data are not available from wells, it is not known if a low resistivity value measured with DC resistivity alone results from the geologic material (clay) or elevated SC in groundwater (in sand or gravel). Seismic surface waves used as part of the MASW technique are not affected by water content or quality and are used herein to distinguish between sand and clay when SC is high. Through concurrent interpretation of MASW and DC-resistivity surveys, information was gained about water quality and lithology over large areas at the SCD site.

  7. DGSAT: Dwarf Galaxy Survey with Amateur Telescopes. I. Discovery of low surface brightness systems around nearby spiral galaxies

    Science.gov (United States)

    Javanmardi, B.; Martinez-Delgado, D.; Kroupa, P.; Henkel, C.; Crawford, K.; Teuwen, K.; Gabany, R. J.; Hanson, M.; Chonis, T. S.; Neyer, F.

    2016-04-01

    Context. We introduce the Dwarf Galaxy Survey with Amateur Telescopes (DGSAT) project and report the discovery of eleven low surface brightness (LSB) galaxies in the fields of the nearby galaxies NGC 2683, NGC 3628, NGC 4594 (M 104), NGC 4631, NGC 5457 (M 101), and NGC 7814. Aims: The DGSAT project aims to use the potential of small-sized telescopes to probe LSB features around large galaxies and to increase the sample size of the dwarf satellite galaxies in the Local Volume. Methods: Using long exposure images, fields of the target spiral galaxies are explored for extended LSB objects. After identifying dwarf galaxy candidates, their observed properties are extracted by fitting models to their light profiles. Results: We find three, one, three, one, one, and two new LSB galaxies in the fields of NGC 2683, 3628, 4594, 4631, 5457, and 7814, respectively. In addition to the newly found galaxies, we analyse the structural properties of nine already known galaxies. All of these 20 dwarf galaxy candidates have effective surface brightnesses in the range 25.3 ≲ μe ≲ 28.8 mag arcsec-2 and are fit with Sersic profiles with indices n ≲ 1. Assuming that they are in the vicinity of the above mentioned massive galaxies, their r-band absolute magnitudes, their effective radii, and their luminosities are in the ranges -15.6 ≲ Mr ≲ -7.8, 160 pc ≲ Re ≲ 4.1 kpc, and 0.1 × 106 ≲ (L/L⊙)r ≲ 127 × 106, respectively. To determine whether these LSB galaxies are indeed satellites of the above mentioned massive galaxies, their distances need to be determined via further observations. Conclusions: Using small telescopes, we are readily able to detect LSB galaxies with similar properties to the known dwarf galaxies of the Local Group.

  8. The Prescribed Velocity Method

    DEFF Research Database (Denmark)

    Nielsen, Peter Vilhelm

    The- velocity level in a room ventilated by jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jets controls the air movement in the room and, therefore, it is very important that the inlet conditions and the numerical method can generate a satisfactory...

  9. Fast, wide-field and distortion-free telescope with curved detectors for surveys at ultralow surface brightness.

    Science.gov (United States)

    Muslimov, Eduard; Valls-Gabaud, David; Lemaître, Gérard; Hugot, Emmanuel; Jahn, Wilfred; Lombardo, Simona; Wang, Xin; Vola, Pascal; Ferrari, Marc

    2017-11-01

    We present the design of an all-reflective, bifolded Schmidt telescope aimed at surveys of extended astronomical objects with extremely low surface brightness. The design leads to a high image quality without any diffracting spider, a large aperture and field of view (FoV), and a small central obstruction that barely alters the point spread function (PSF). As an example, we design a high-quality, 36 cm diameter, fast (f/2.5) telescope working in the visible with a large FoV (1.6°×2.6°). The telescope can operate with a curved detector (or with a flat detector with a field flattener) and a set of filters. The entrance mirror is anamorphic and replaces the classical Schmidt entrance corrector plate. We show that this anamorphic primary mirror can be manufactured through stress polishing, avoiding high spatial frequency errors, and testing with a simple interferometer scheme. This prototype is intended to serve as a fast-track scientific and technological pathfinder for the future space-based MESSIER mission.

  10. Integrated synoptic surveys using an autonomous underwater vehicle and manned boats

    Science.gov (United States)

    Jackson, P. Ryan

    2013-01-01

    Traditional surface-water surveys are being combined with autonomous technology to produce integrated surveys of bathymetry, water quality, and velocity in inland lakes and reservoirs. This new technology provides valuable, high-resolution, integrated data that allow a systems-based approach to understanding common environmental problems. This fact sheet presents several example applications of integrated surveys within inland lakes and coastal Lake Michigan and Lake Erie.

  11. SURVEY, REPRESENTATION AND ANALYSIS OF A WAR I COMPLEX SYSTEM OF SURFACE AND UNDERGROUND FORTIFICATIONS IN THE GRESTA VALLEY, ITALY

    Directory of Open Access Journals (Sweden)

    I. Salvador

    2012-09-01

    practical advantage of exploiting the natural collapse of the rock along the stratigraphic splices. At the landscape-scale: the 1918's aerial photos, showing the trenches and military barracks during the World War I, have been georeferenced and compared to recent ortho- photos and DTM to evaluate the landscape changes and to assess the complete detection of the entire set of fortified structures. The analysis involved also the evaluation of the landscape visibility from some key points of the fortification and the visibility of the same fortification from the surrounding landscape. That has permitted, for example, to underline the very strategic location of the field kitchen. The availability of the 1×1m ALS DSM suggests a possible processing for the detection of the preserved surface artefacts and trenches so to extend the metric knowledge of the fortification system and to plan further surveys.

  12. Wave propagation and group velocity

    CERN Document Server

    Brillouin, Léon

    1960-01-01

    Wave Propagation and Group Velocity contains papers on group velocity which were published during the First World War and are missing in many libraries. It introduces three different definitions of velocities: the group velocity of Lord Rayleigh, the signal velocity of Sommerfeld, and the velocity of energy transfer, which yields the rate of energy flow through a continuous wave and is strongly related to the characteristic impedance. These three velocities are identical for nonabsorbing media, but they differ considerably in an absorption band. Some examples are discussed in the last chapter

  13. The Radial Variation of H I Velocity Dispersions in Dwarfs and Spirals

    Science.gov (United States)

    Ianjamasimanana, R.; de Blok, W. J. G.; Walter, Fabian; Heald, George H.; Caldú-Primo, Anahi; Jarrett, Thomas H.

    2015-08-01

    Gas velocity dispersions provide important diagnostics of the forces counteracting gravity to prevent collapse of the gas. We use the 21 cm line of neutral atomic hydrogen (H i) to study H i velocity dispersion ({σ }{{H} {{I}}}) and H i phases as a function of galaxy morphology in 22 galaxies from The H i Nearby Galaxy Survey. We stack individual H i velocity profiles and decompose them into broad and narrow Gaussian components. We study the H i velocity dispersion and the H i surface density, {{{Σ }}}{{H} {{I}}}, as a function of radius. For spirals, the velocity dispersions of the narrow and broad components decline with radius and their radial profiles are well described by an exponential function. For dwarfs, however, the profiles are much flatter. The single Gaussian dispersion profiles are, in general, flatter than those of the narrow and broad components. In most cases, the dispersion profiles in the outer disks do not drop as fast as the star formation profiles derived in the literature. This indicates the importance of other energy sources in driving {σ }{{H} {{I}}} in the outer disks. The radial surface density profiles of spirals and dwarfs are similar. The surface density profiles of the narrow component decline more steeply than those of the broad component, but not as steep as what was found previously for the molecular component. As a consequence, the surface density ratio between the narrow and broad components, an estimate of the mass ratio between cold H i and warm H i, tends to decrease with radius. On average, this ratio is lower in dwarfs than in spirals. This lack of a narrow, cold H i component in dwarfs may explain their low star formation activity.

  14. Ground-Control Networks for Image Based Surface Reconstruction: An Investigation of Optimum Survey Designs Using UAV Derived Imagery and Structure-from-Motion Photogrammetry

    Directory of Open Access Journals (Sweden)

    Toby N. Tonkin

    2016-09-01

    Full Text Available The use of small UAV (Unmanned Aerial Vehicle and Structure-from-Motion (SfM with Multi-View Stereopsis (MVS for acquiring survey datasets is now commonplace, however, aspects of the SfM-MVS workflow require further validation. This work aims to provide guidance for scientists seeking to adopt this aerial survey method by investigating aerial survey data quality in relation to the application of ground control points (GCPs at a site of undulating topography (Ennerdale, Lake District, UK. Sixteen digital surface models (DSMs were produced from a UAV survey using a varying number of GCPs (3-101. These DSMs were compared to 530 dGPS spot heights to calculate vertical error. All DSMs produced reasonable surface reconstructions (vertical root-mean-square-error (RMSE of <0.2 m, however, an improvement in DSM quality was found where four or more GCPs (up to 101 GCPs were applied, with errors falling to within the suggested point quality range of the survey equipment used for GCP acquisition (e.g., vertical RMSE of <0.09 m. The influence of a poor GCP distribution was also investigated by producing a DSM using an evenly distributed network of GCPs, and comparing it to a DSM produced using a clustered network of GCPs. The results accord with existing findings, where vertical error was found to increase with distance from the GCP cluster. Specifically vertical error and distance to the nearest GCP followed a strong polynomial trend (R2 = 0.792. These findings contribute to our understanding of the sources of error when conducting a UAV-SfM survey and provide guidance on the collection of GCPs. Evidence-driven UAV-SfM survey designs are essential for practitioners seeking reproducible, high quality topographic datasets for detecting surface change.

  15. Transverse Spectral Velocity Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    array probe is used along with two different estimators based on the correlation of the received signal. They can estimate the velocity spectrum as a function of time as for ordinary spectrograms, but they also work at a beam-to-flow angle of 90°. The approach is validated using simulations of pulsatile...... flow using the Womersly–Evans flow model. The relative bias of the mean estimated frequency is 13.6% and the mean relative standard deviation is 14.3% at 90°, where a traditional estimator yields zero velocity. Measurements have been conducted with an experimental scanner and a convex array transducer....... A pump generated artificial femoral and carotid artery flow in the phantom. The estimated spectra degrade when the angle is different from 90°, but are usable down to 60° to 70°. Below this angle the traditional spectrum is best and should be used. The conventional approach can automatically be corrected...

  16. High-Velocity Clouds

    CERN Document Server

    Woerden, Hugo; Schwarz, Ulrich J; Boer, Klaas S

    2005-01-01

    This book contains 17 chapters reviewing our knowledge of the high-velocity clouds (HVCs) as of 2004, bringing this together in one place for the first time. Each of the many different aspects of HVC research is addressed by one of the experts in that subfield. These include a historical overview of HVC research and analyses of the structure and kinematics of HVCs. Separate chapters address the intermediate-velocity clouds, the Magellanic Stream, and neutral hydrogen HVCs discovered in external galaxies. Reviews are presented of the Ha emission and of optical and UV absorption-line studies, followed by discussions of the hot Galactic Halo and of the interactions between HVCs and their surroundings. Four chapters summarize the ideas about the origin of the high-velocity gas, with detailed discussions of connections between HVCs and the Galactic Fountain, tidally-stripped material, and remnants of the Milky Way's formation. A chapter outlining what we do not know completes the book. The book comes at a time whe...

  17. Integrative velocity model building for imaging a geothermal reservoir in southern Tuscany, Italy

    Science.gov (United States)

    Schreiter, Lena; Loch, Felix; Ciuffi, Simonetta; Buske, Stefan

    2017-04-01

    Deep geothermal reservoirs are generally characterized by high temperatures and pressures, sometimes located in hard rock environments and even close to a super-critical state. For characterization of such a deep super-critical geothermal reservoir, the imaging of the subsurface at the highest possible resolution is required to reduce the uncertainties in exploration prior to the drilling phase. Several seismic surveys were carried out for characterization of a possible drilling target within a deep super-critical geothermal reservoir in Tuscany (project DESCRAMBLE). Seismic data were acquired in the form of 2D seismic reflection surveys as well as Vertical Seismic Profiling (VSP), the latter complemented by simultaneous recording of the source signals by a surface network covering an area of approximately 6 km x 6 km around the drill site. The investigation area itself is characterized by a complex geology with strong velocity contrasts, near-surface inhomogeneities and fracture zones. At first, the processing of the recorded seismic wavefields aimed at the determination of a seismic velocity model by a multidisciplinary approach. The application of conventional methods is limited due to the low resolution of the stacking velocities, significant lateral velocity changes and strong influence of noise. We performed first-arrival traveltime tomography and derived borehole velocities to tackle the complexity of the geology. Below the bottom of the borehole, results from laboratory measurements of rock samples from deeper neighboring wells were integrated into the velocity model. This approach limits the ambiguity, which depends on the existence and distribution of the neighboring wells in the investigation area. The results contribute to a robust migration velocity model used for an uncertainty depth analysis at the target horizon. In a next step, the influence of the velocity model on imaging is tested within an advanced seismic imaging workflow for several 2D

  18. Periodicity for 50 yr of daily solar wind velocity

    Science.gov (United States)

    Li, K. J.; Zhang, J.; Feng, W.

    2017-11-01

    Daily mean velocity of solar wind that was surveyed near the Earth's orbit at about 1 au from 1963 November 27 to 2015 November 30 and issued by OMNIWeb is used to look into its periodicity through the Lomb-Scargle periodogram method. As the strongest periodical signal, the solar activity cycle of about 10.4 yr is found in high-velocity wind, but in low-velocity wind, the 9.17-yr cycle appears instead. The rotation cycle of about 27 d and its 1/2 and 1/3 harmonic periods are clearly detected in all-, low- and high-velocity wind, and at their periodograms, several individual periodical peaks appear very close to the peaks of these three periods. The annual period of about 1.07 yr is identified for both all- and low-velocity wind, but not for high-velocity wind after 1994. The 1.68-yr period occurs in all- and high-velocity wind, but does not appear in low-velocity wind. The period of about 2.42 yr appears just in the all-velocity wind after 1994, but its twofold period (about 4.83 yr) appears in both all- and high-velocity wind. The period of about 4.1 yr occurs in all-, low- and high-velocity wind. The possible origin of these periods is discussed.

  19. Preliminary results of high resolution subbottom survey and surface sediment sampling by ROV "NSS" in the Nankai subduction zone off Kumano

    Science.gov (United States)

    Ashi, J.; Kh-10-3 Science Party

    2010-12-01

    The Nankai subduction zone off Kumano has been extensively investigated for site surveys of IODP Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) by bathymetirc survey, 2D and 3D seismic reflection survey, dive observation and sidescan sonar survey. However, subbottom profiling and surface sediment sampling were limited due to steep and complex topography under strong Kuroshio Current. We carried out deep-tow subbottom survey and pinpoint core sampling by ROV "NSS (Navigable Sampling System)" of Atmosphere and Ocean Research Institute, the Univ. Tokyo during Hakuho-maru KH-10-3 cruise. A pilot vehicle of NSS is equipped with four thrusters, observation cameras and a hock for a heavy payload. Depth capability of the pilot vehicle is 4000 m and maximum payload weight is 1.5 tons. We introduced a chirp subbottom profiling system of EdgeTech DW-106 for high resolution mapping of shallow structures and determination of a sampling point on this year's survey. Three survey lines crossed the splay fault area around IODP drilling sites. Subbottom profiles show that seafloor is completely covered by stratified sediments and any fault displacement cannot be identified although maximum penetration of chirp signal is only 15 meters in prism slope regions. In contrast, landward progressive tilting of slope basin sediments and talus deposits on it are well imaged along the steep scarp 30 km southwest of the drilling sites. Dense chemosynthetic biological community revealed by camera observations also suggests existence of active fault in this area. The scarp more gentle slope than the above is located 4 kilometers trenchward of it. Subbottom profiles show well-stratified sediment cover without fault deformation. Seismic reflection profiles and existence of dense traces of bivalves, however, suggest existence of a splay fault beneath it. A long-term heat flow meter of ERI, Univ. Tokyo was installed at each fault scarp for monitoring of cold seep activity. We also present

  20. Washington Center's Online Student Survey Validation Study: Surfacing Students' Individual and Collective Understanding of Their Learning Community Experiences

    Science.gov (United States)

    Malnarich, Gillies; Pettitt, Maureen A.; Mino, Jack J.

    2014-01-01

    This article reports on findings from a mixed-methods validation study of the "Online Survey of Students' Experiences of Learning in Learning Communities". In the quantitative part of the study, we found strong correlations among survey items related to faculty behaviors, student behaviors, and critical thinking. Factor analysis yielded…

  1. Location of sound velocity profiles along with profile plots collected by the U.S. Geological Survey in 2014 along the Delmarva Peninsula, MD and VA (PNG images, CSV text, and Esri point shapefile, Geographic, WGS 84)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Delmarva Peninsula is a 220-kilometer-long headland, spit, and barrier island complex that was significantly affected by Hurricane Sandy. A U.S. Geological...

  2. Sound velocity profile locations collected by the U.S. Geological Survey in Moultonborough Bay, Lake Winnipesaukee, New Hampshire in 2005 (Geographic, WGS 84, Esri point shapefile, 2005-004-FA_SVP.SHP)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — In freshwater bodies of New Hampshire, the most problematic aquatic invasive plant species is Myriophyllum heterophyllum or variable leaf water-milfoil. Once...

  3. The velocity source concept

    NARCIS (Netherlands)

    van Suchtelen, J.; Nijdam, A.J.; van Veenendaal, E.

    1999-01-01

    Traditional kinematic wave theory neglects considerations involving free energy of a surface and nucleation at the boundary of a surface. As a consequence, strictly speaking this theory is only applicable to freely floating perfect crystals, and when applied to more complex situations the

  4. U.S. Geological Survey: Surface-Water Historical Instantaneous Data for the Nation: Build Time Series

    Data.gov (United States)

    U.S. Environmental Protection Agency — The USGS historical data base contains historical surface water discharge volume data for all 16,658 surface water sites that have current conditions. This dataset...

  5. Shock wave velocity measuring system based on vernier VISAR-type interferometers

    Science.gov (United States)

    Gubskii, K. L.; Koshkin, D. S.; Antonov, A. S.; Mikhailuk, A. V.; Pirog, V. A.; Kuznetsov, A. P.

    2015-11-01

    The paper presents a multi-line diagnostic system for measuring the surface velocity in shock physics experiments. This system is designed for simultaneous measurement of surface velocity at multiple points. It is free from ambiguity caused by harmonic dependence of interference signals on the velocity and has a time resolution of 0.8 ns.

  6. JET VELOCITY OF LINEAR SHAPED CHARGES

    Directory of Open Access Journals (Sweden)

    Vječislav Bohanek

    2012-12-01

    Full Text Available Shaped explosive charges with one dimension significantly larger than the other are called linear shaped charges. Linear shaped charges are used in various industries and are applied within specific technologies for metal cutting, such as demolition of steel structures, separating spent rocket fuel tanks, demining, cutting holes in the barriers for fire service, etc. According to existing theories and models efficiency of linear shaped charges depends on the kinetic energy of the jet which is proportional to square of jet velocity. The original method for measuring velocity of linear shaped charge jet is applied in the aforementioned research. Measurements were carried out for two different linear materials, and the results are graphically presented, analysed and compared. Measurement results show a discrepancy in the measured velocity of the jet for different materials with the same ratio between linear and explosive mass (M/C per unit of surface, which is not described by presented models (the paper is published in Croatian.

  7. Examples of Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Hansen, Peter M.; Pedersen, Mads M.; Hansen, Kristoffer L.

    2011-01-01

    To measure blood flow velocity in vessels with conventional ultrasound, the velocity is estimated along the direction of the emitted ultrasound wave. It is therefore impossible to obtain accurate information on blood flow velocity and direction, when the angle between blood flow and ultrasound wa...

  8. A non-parametric model for the cosmic velocity field

    NARCIS (Netherlands)

    Branchini, E; Teodoro, L; Frenk, CS; Schmoldt, [No Value; Efstathiou, G; White, SDM; Saunders, W; Sutherland, W; Rowan-Robinson, M; Keeble, O; Tadros, H; Maddox, S; Oliver, S

    1999-01-01

    We present a self-consistent non-parametric model of the local cosmic velocity field derived from the distribution of IRAS galaxies in the PSCz redshift survey. The survey has been analysed using two independent methods, both based on the assumptions of gravitational instability and linear biasing.

  9. Range of wavelengths possible to estimate phase velocities of surface waves in microtremors; Bido tansaho ni okeru suitei kanona bidochu no hyomenha iso sokudo no hacho han`i

    Energy Technology Data Exchange (ETDEWEB)

    Miyakoshi, K.; Okada, H.; Ling, S. [Hokkaido University, Sapporo (Japan)

    1996-05-01

    To specify the maximum wavelength of the phase velocities that can be estimated by the spatial autocorrelation (SPAC) method or F-K method in microtremor exploration, investigations were conducted using numerical simulation. In view of feasibility, an equilateral triangle array was employed, the maximum radius of the array having 7 observation points being 0.10km. The dispersion curve of the Rayleigh wave basic mode was calculated from an underground structure model. White noise was used as the incident wave, and, in case the waves came in from multiple directions, a different phase spectrum was assigned to each direction. In searching for the maximum wave length of phase velocities that could be estimated, a limit was imposed upon estimation, and it was prescribed that the wavelength be the limit if the difference between the theoretical value and estimated phase velocity was 5% or higher. As the result, it was found that it is possible to estimate the phase velocity when the wavelength is up to approximately 10 times longer than the array maximum radius in the SPAC method, and up to approximately 5 times longer in case of the F-K method. 10 refs., 5 figs., 1 tab.

  10. Corrosion and Biofouling on the Non-Heat-Exchanger Surfaces of an Ocean Thermal Energy Conversion Power Plant. A Survey

    Science.gov (United States)

    1979-05-01

    the structure. During construction, the reinforcing mats or fabrics are overlapped or oriented to provide adequate distribution of stress and to give...900 (600) All over (coastal waters) Tunicates Surface to 500 All over Borers Surface to bottom (7,000) All over Jellyfish Surface to bottom All over...serious fouling problems. However, the ingestion of large volumea of water may entrap swimming nuarine 52 life which could cause obstruction and

  11. Development of an optimal velocity selection method with velocity obstacle

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Geuk; Oh, Jun Ho [KAIST, Daejeon (Korea, Republic of)

    2015-08-15

    The Velocity obstacle (VO) method is one of the most well-known methods for local path planning, allowing consideration of dynamic obstacles and unexpected obstacles. Typical VO methods separate a velocity map into a collision area and a collision-free area. A robot can avoid collisions by selecting its velocity from within the collision-free area. However, if there are numerous obstacles near a robot, the robot will have very few velocity candidates. In this paper, a method for choosing optimal velocity components using the concept of pass-time and vertical clearance is proposed for the efficient movement of a robot. The pass-time is the time required for a robot to pass by an obstacle. By generating a latticized available velocity map for a robot, each velocity component can be evaluated using a cost function that considers the pass-time and other aspects. From the output of the cost function, even a velocity component that will cause a collision in the future can be chosen as a final velocity if the pass-time is sufficiently long enough.

  12. The soil moisture velocity equation

    Science.gov (United States)

    Ogden, Fred L.; Allen, Myron B.; Lai, Wencong; Zhu, Jianting; Seo, Mookwon; Douglas, Craig C.; Talbot, Cary A.

    2017-06-01

    Numerical solution of the one-dimensional Richards' equation is the recommended method for coupling groundwater to the atmosphere through the vadose zone in hyperresolution Earth system models, but requires fine spatial discretization, is computationally expensive, and may not converge due to mathematical degeneracy or when sharp wetting fronts occur. We transformed the one-dimensional Richards' equation into a new equation that describes the velocity of moisture content values in an unsaturated soil under the actions of capillarity and gravity. We call this new equation the Soil Moisture Velocity Equation (SMVE). The SMVE consists of two terms: an advection-like term that accounts for gravity and the integrated capillary drive of the wetting front, and a diffusion-like term that describes the flux due to the shape of the wetting front capillarity profile divided by the vertical gradient of the capillary pressure head. The SMVE advection-like term can be converted to a relatively easy to solve ordinary differential equation (ODE) using the method of lines and solved using a finite moisture-content discretization. Comparing against analytical solutions of Richards' equation shows that the SMVE advection-like term is >99% accurate for calculating infiltration fluxes neglecting the diffusion-like term. The ODE solution of the SMVE advection-like term is accurate, computationally efficient and reliable for calculating one-dimensional vadose zone fluxes in Earth system and large-scale coupled models of land-atmosphere interaction. It is also well suited for use in inverse problems such as when repeat remote sensing observations are used to infer soil hydraulic properties or soil moisture.Plain Language SummarySince its original publication in 1922, the so-called Richards' equation has been the only rigorous way to couple groundwater to the land surface through the unsaturated zone that lies between the water table and land surface. The soil moisture distribution and

  13. Carbon dioxide from surface underway survey in global oceans from 1968 to 2006 (Version 1.0) (NODC Accession 0040205)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — More than 3 million measurements of surface water partial pressure of CO2 obtained over the global oceans during 1968 to 2006 are listed in the Lamont-Doherty Earth...

  14. Results of the measurement survey of elevation and environmental media in surface impoundments 3513 (B) and 3524 (A) at Oak Ridge National Laboratory, Oak Ridge, TN

    Energy Technology Data Exchange (ETDEWEB)

    Murray, M.E.; Rose, D.A.; Brown, K.S.; Coe, R.H.C. III; Lawrence, J.D.; Winton, W.

    1998-07-01

    A measurement survey of the elevation and environmental media in impoundments 3513 (B) and 3524 (A) at the Oak Ridge National Laboratory (ORNL) was conducted during April 1998. The investigation was performed by the Measurement Applications and Development Group of the Life Sciences Division of ORNL at the request of Bechtel Jacobs Company. Measurement activities were conducted at selected locations in order to determine the depth and appearance of the sediment and describe the clay underlying the impoundments prior to remediation. The survey was a follow-up to a previous elevation survey. The survey included the following: collection of sediment/clay cores from selected locations in each impoundment; measurement and documentation of the elevation at the water surface, at the top of sediment, at the top of clay, and at the bottom of each core; visual inspection of each core by a soil scientist to confirm the presence of clay and not material such as fly ash and soda lime compacted over the last 50 years; measurement and documentation of the background beta-gamma radiation level at the time and location of collection of each core, the highest beta-gamma level along the sediment portion of each core, and the highest beta-gamma level along the clay portion of each core; measurement and documentation of the length of the clay and of the sediment portion of each core; photographic documentation of each core; and replacement of each core in the impoundment.

  15. Final report: survey and removal of radioactive surface contamination at environmental restoration sites, Sandia National Laboratories/New Mexico. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, K.A.; Mitchell, M.M. [Brown and Root Environmental, Albuquerque, NM (United States); Jean, D. [MDM/Lamb, Inc., Albuquerque, NM (United States); Brown, C. [Environmental Dimensions, Inc., Albuquerque, NM 87109 (United States); Byrd, C.S. [Sandia National Labs., Albuquerque, NM (United States)

    1997-09-01

    This report describes the survey and removal of radioactive surface contamination at Sandia`s Environmental Restoration (ER) sites. Radiological characterization was performed as a prerequisite to beginning the Resource Conservation and Recovery Act (RCRA) corrective action process. The removal of radioactive surface contamination was performed in order to reduce potential impacts to human health and the environment. The predominant radiological contaminant of concern was depleted uranium (DU). Between October 1993 and November 1996 scanning surface radiation surveys, using gamma scintillometers, were conducted at 65 sites covering approximately 908 acres. A total of 9,518 radiation anomalies were detected at 38 sites. Cleanup activities were conducted between October 1994 and November 1996. A total of 9,122 anomalies were removed and 2,072 waste drums were generated. The majority of anomalies not removed were associated with a site that has subsurface contamination beyond the scope of this project. Verification soil samples (1,008 total samples) were collected from anomalies during cleanup activities and confirm that the soil concentration achieved in the field were far below the target cleanup level of 230 pCi/g of U-238 (the primary constituent of DU) in the soil. Cleanup was completed at 21 sites and no further radiological action is required. Seventeen sites were not completed since cleanup activities wee precluded by ongoing site activity or were beyond the original project scope.

  16. Velocity and strain-rate analyses of the SCEC 3.0 velocity field

    Science.gov (United States)

    Wdowinski, S.; Bock, Y.

    2003-04-01

    The pre-released SCEC 3.0 velocity field consists of 845 velocity vectors, covering the entire Southern California region. It is about 3 times larger than the SCEC 2.0 field, which was released in 1998 and contains 343 velocity vectors. We analyze the new SCEC 3.0 velocity field following and improving the quasi-two-dimensional analyses developed by Wdowinski et al. [2001] for the 2.0 velocity field. The new analyses include the following steps: (1) Pole of Deformation (PoD) calculation; the PoD is a point on the Earth’s surface, in which small circles about this point are best, aligned with the velocity vectors of the deforming zone. (2) Transforming the velocity field into the PoD reference frame. (3) Characterization of the velocity field by segments of similar velocity transition between the Pacific and North American plates and orthogonal profiles along the plate boundary region. (4) Calculating velocity and velocity gradient for all segments and profiles using zero-phase digital filters and numerical derivation, respectively. (5) Calculation of regional strain-rate maps, and (6) back-transformation of the strain-rate maps into the regular north-pole reference frame. The results of our analyses show that shear deformation with high strain-rate is detected along a dozen narrow belts, which coincide with active geologic fault segments and high level of seismicity along the San Andreas Fault System. In the highly populated Los Angeles area, our analyses detected high strain-rate localization along the Newport-Inglewood fault and across the Ventura Basin. In the regional scale, our analyses show that the interseismic deformation of the wide diffused deforming NA-PA plate boundary region is localized along a finite number of narrow belts. Because no prior assumptions were made regarding the geology, tectonics, or seismicity of the region, our analysis demonstrates that geodetic observations alone can be used to detect active fault segments.

  17. Wave measurements using GPS velocity signals.

    Science.gov (United States)

    Doong, Dong-Jiing; Lee, Beng-Chun; Kao, Chia Chuen

    2011-01-01

    This study presents the idea of using GPS-output velocity signals to obtain wave measurement data. The application of the transformation from a velocity spectrum to a displacement spectrum in conjunction with the directional wave spectral theory are the core concepts in this study. Laboratory experiments were conducted to verify the accuracy of the inversed displacement of the surface of the sea. A GPS device was installed on a moored accelerometer buoy to verify the GPS-derived wave parameters. It was determined that loss or drifting of the GPS signal, as well as energy spikes occurring in the low frequency band led to erroneous measurements. Through the application of moving average skill and a process of frequency cut-off to the GPS output velocity, correlations between GPS-derived, and accelerometer buoy-measured significant wave heights and periods were both improved to 0.95. The GPS-derived one-dimensional and directional wave spectra were in agreement with the measurements. Despite the direction verification showing a 10° bias, this exercise still provided useful information with sufficient accuracy for a number of specific purposes. The results presented in this study indicate that using GPS output velocity is a reasonable alternative for the measurement of ocean waves.

  18. GLOBAL PROPERTIES OF M31'S STELLAR HALO FROM THE SPLASH SURVEY. I. SURFACE BRIGHTNESS PROFILE

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Karoline M. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Guhathakurta, Puragra [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Beaton, Rachael L.; Majewski, Steven R.; Ostheimer, James C.; Patterson, Richard J. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Bullock, James; Tollerud, Erik J. [Center for Cosmology, Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697 (United States); Geha, Marla C. [Astronomy Department, Yale University, New Haven, CT 06520 (United States); Kalirai, Jason S. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Kirby, Evan N. [California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Tanaka, Mikito; Chiba, Masashi, E-mail: kgilbert@astro.washington.edu [Astronomical Institute, Tohoku University, Aoba-ku, Sendai 980-8578 (Japan)

    2012-11-20

    We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnostics is used to identify and reject foreground and background contaminants. This enables us to trace the stellar halo of M31 to larger projected distances and fainter surface brightnesses than previous photometric studies. The surface brightness profile of M31's halo follows a power law with index -2.2 {+-} 0.2 and extends to a projected distance of at least {approx}175 kpc ({approx}2/3 of M31's virial radius), with no evidence of a downward break at large radii. The best-fit elliptical isophotes have b/a = 0.94 with the major axis of the halo aligned along the minor axis of M31's disk, consistent with a prolate halo, although the data are also consistent with M31's halo having spherical symmetry. The fact that tidal debris features are kinematically cold is used to identify substructure in the spectroscopic fields out to projected radii of 90 kpc and investigate the effect of this substructure on the surface brightness profile. The scatter in the surface brightness profile is reduced when kinematically identified tidal debris features in M31 are statistically subtracted; the remaining profile indicates that a comparatively diffuse stellar component to M31's stellar halo exists to large distances. Beyond 90 kpc, kinematically cold tidal debris features cannot be identified due to small number statistics; nevertheless, the significant field-to-field variation in surface brightness beyond 90 kpc suggests that the outermost region of M31's halo is also comprised to a significant degree of stars stripped from accreted objects.

  19. Friction model for the velocity dependence of nanoscale friction.

    Science.gov (United States)

    Tambe, Nikhil S; Bhushan, Bharat

    2005-10-01

    The velocity dependence of nanoscale friction is studied for the first time over a wide range of velocities between 1 microm s(-1) and 10 mm s(-1) on large scan lengths of 2 and 25 microm. High sliding velocities are achieved by modifying an existing commercial atomic force microscope (AFM) setup with a custom calibrated nanopositioning piezo stage. The friction and adhesive force dependences on velocity are studied on four different sample surfaces, namely dry (unlubricated), hydrophilic Si(100); dry, partially hydrophobic diamond-like carbon (DLC); a partially hydrophobic self-assembled monolayer (SAM) of hexadecanethiol (HDT); and liquid perfluoropolyether lubricant, Z-15. The friction force values are seen to reverse beyond a certain critical velocity for all the sample surfaces studied. A comprehensive friction model is developed to explain the velocity dependence of nanoscale friction, taking into consideration the contributions of adhesion at the tip-sample interface, high impact velocity-related deformation at the contacting asperities and atomic scale stick-slip. A molecular spring model is used for explaining the velocity dependence of friction force for HDT.

  20. The Importance of Baseline Surveys of Near-Surface Gas Geochemistry for CCS Monitoring, as Shown from Onshore Case Studies in Northern and Southern Europe

    Directory of Open Access Journals (Sweden)

    Beaubien Stan E.

    2015-04-01

    Full Text Available The monitoring of the integrity of onshore geological carbon capture and storage projects will require an approach that integrates various methods with different spatial and temporal resolutions. One method proven to be quite effective for site assessment, leakage monitoring, and leakage verification is near-surface gas geochemistry, which includes soil gas concentration and gas flux measurements. Anomalous concentrations or fluxes, relative to the natural background values, can indicate the potential occurrence of a leak. However the natural background can be quite variable, especially for CO2, due to biological production and accumulation in the soil that changes as a function of soil type, land use, geology, temperature, water content, and various other parameters. To better understand how these parameters influence natural, near-surface background values, and to examine the potential of different sampling strategies as a function of the survey goals, this paper reports results from two highly different case studies, one from northern Europe (Voulund, Denmark and one from southern Europe (Sulcis, Sardinia, Italy. The small Voulund site, with its homogeneous soil, climate, and topography, was surveyed twice (in fall and in spring within the EU-funded SiteChar project to examine the effects of different land use practices and seasons on baseline values. Forested land was found to have lower CO2 concentrations during both campaigns compared to cultivated and heath land, and higher CH4 values during the spring sampling campaign. Continuous monitoring probes showed much more detail, highlighting seasonal changes in soil gas CO2 concentrations linked primarily to temperature variations. The much larger Sulcis site, studied within an ENEA-funded project on potential CO2-ECBM (Enhanced Coal Bed Methane deployment, was surveyed at the regional scale and on detailed grids and transects for site assessment purposes. Despite the completely different soil

  1. Rayleigh-Wave Group-Velocity Tomography of Saudi Arabia

    Science.gov (United States)

    Tang, Zheng; Mai, P. Martin; Chang, Sung-Joon; Zahran, Hani

    2017-04-01

    We use surface-wave tomography to investigate the lithospheric structure of the Arabian plate, which is traditionally divided into the Arabian shield in the west and the Arabian platform in the east. The Arabian shield is a complicated mélange of crustal material, composed of several Proterozoic terrains separated by ophiolite-bearing suture zones and dotted by outcropping Cenozoic volcanic rocks. The Arabian platform is primarily covered by very thick Paleozoic, Mesozoic and Cenozoic sediments. We develop high-resolution tomographic images from fundamental-mode Rayleigh-wave group-velocities across Saudi Arabia, utilizing the teleseismic data recorded by the permanent Saudi National Seismic Network (SNSN). Our study extends previous efforts on surface wave work by increasing ray path density and improving spatial resolution. Good quality dispersion measurements for roughly 3000 Rayleigh-wave paths have been obtained and utilized for the group-velocity tomography. We have applied the Fast Marching Surface Tomography (FMST) scheme of Rawlinson (2005) to obtain Rayleigh-wave group-velocity images for periods from 8 s to 40 s on a 0.8° 0.8° grid and at resolutions approaching 2.5° based on the checkerboard tests. Our results indicate that short-period group-velocity maps (8-15 s) correlate well with surface geology, with slow velocities delineating the main sedimentary features including the Arabian platform, the Persian Gulf and Mesopotamia. For longer periods (20-40 s), the velocity contrast is due to the differences in crustal thickness and subduction/collision zones. The lower velocities are sensitive to the thicker continental crust beneath the eastern Arabia and the subduction/collision zones between the Arabian and Eurasian plate, while the higher velocities in the west infer mantle velocity.

  2. Kaleidoscopic motion and velocity illusions

    NARCIS (Netherlands)

    Helm, P.A. van der

    2007-01-01

    A novel class of vivid motion and velocity illusions for contrast-defined shapes is presented and discussed. The illusions concern a starlike wheel that, physically, rotates with constant velocity between stationary starlike inner and outer shapes but that, perceptually, shows pulsations, jolts

  3. Monthly dynamics of carbon dioxide exchange across the sea surface of the Arctic Ocean in response to changes in gas transfer velocity and partial pressure of CO2 in 2010

    Directory of Open Access Journals (Sweden)

    Iwona Wrobel

    2017-10-01

    Full Text Available The Arctic Ocean (AO is an important basin for global oceanic carbon dioxide (CO2 uptake, but the mechanisms controlling air–sea gas fluxes are not fully understood, especially over short and long timescales. The oceanic sink of CO2 is an important part of the global carbon budget. Previous studies have shown that in the AO differences in the partial pressure of CO2 (ΔpCO2 and gas transfer velocity (k both contribute significantly to interannual air–sea CO2 flux variability, but that k is unimportant for multidecadal variability. This study combined Earth Observation (EO data collected in 2010 with the in situ pCO2 dataset from Takahashi et al. (2009 (T09 using a recently developed software toolbox called FluxEngine to determine the importance of k and ΔpCO2 on CO2 budgets in two regions of the AO – the Greenland Sea (GS and the Barents Sea (BS with their continental margins. Results from the study indicate that the variability in wind speed and, hence, the gas transfer velocity, generally play a major role in determining the temporal variability of CO2 uptake, while variability in monthly ΔpCO2 plays a major role spatially, with some exceptions.

  4. Transport velocity of droplets on ratchet conveyors.

    Science.gov (United States)

    Holmes, Hal R; Böhringer, Karl F

    2017-09-14

    Anisotropic ratchet conveyors (ARC) are a type of digital microfluidic system. Unlike electrowetting based systems, ARCs transport droplets through a passive, micro-patterned surface and applied orthogonal vibrations. The mechanics of droplet transport on ARC devices has yet to be as well characterized and understood as on electrowetting systems. In this work, we investigate how the design of the ARC substrate affects the droplet response to vibrations and perform the first characterization of transport velocity on ARC devices. We discovered that the design of the ARC device has a significant effect on both the transport efficiency and velocity of actuated droplets, and that the amplitude of the applied vibration can modulate the velocity of transported droplets. Finally, we show that the movement of droplet edges is not continuous but rather the sum of quantized steps between features of the ARC device. These results provide new insights into the behavior of droplets vibrated on asymmetric surface patterns and will serve as the foundation for the design and development of future lab-on-a-chip systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. GEODVEL, MORVEL, and the velocity of Earth's center (Invited)

    Science.gov (United States)

    Argus, D.; Gordon, R. G.; Demets, C.

    2010-12-01

    Estimates of plate velocities from geodesy depend on the velocity of Earth’s center, which is the point relative to which geodetic site motions are described. In GEODVEL [Argus et al. 2010], a set of estimates of the velocities of 11 plates from space observations from GPS, SLR, VLBI, and DORIS over 25 yr, we define Earth’s center to be (CE) the mass center of solid Earth. We simultaneously estimate the angular velocities of the plates and the velocity of CE assuming that, besides plate motion, the parts of the plate interiors not near the late Pleistocene ice sheets are not moving horizontally relative to CE, that is, that these parts of the plate interiors are rigid laterally. We find the velocity of CE to differ significantly from the velocity of CM in ITRF2005 and ITRF2008. The velocity of CE that we estimate is likely nearer the velocity of (CM) the composite mass center of solid Earth, oceans, and atmosphere than the estimates in ITRF2005 and ITRF2008 because (1) no phenomena can sustain a velocity between CE and CM, (2) the plate interiors are indeed nearly rigid, and (3) estimates of the velocity of CM from SLR observation of satellite LAGEOS differ between ITRF2000 and ITRF2005 by an unacceptably large 1.8 mm/yr. Plate velocities in GEODVEL differ significantly from those in geologically current plate motion model MORVEL [DeMets et al. 2010], which is estimated mainly from transform azimuths and spreading rates from magnetic anomalies 1 to 3 Myr. The median vector difference between the GEODVEL and MORVEL sets of angular velocities is 0.046 °/Myr, which is on average ≈2.5 mm/yr along Earth’s surface. The biggest change in plate velocity since 3 Ma is that the east component of velocity of the Nazca plate has slowed. A second big change is that the north component of velocity of Nubia, Arabia, and India relative to Eurasia has slowed, because continental crust is difficult to subduct. The velocities of composite plates (e.g. Nubia, Somalia and

  6. Diffraction imaging and velocity analysis using oriented velocity continuation

    KAUST Repository

    Decker, Luke

    2014-08-05

    We perform seismic diffraction imaging and velocity analysis by separating diffractions from specular reflections and decomposing them into slope components. We image slope components using extrapolation in migration velocity in time-space-slope coordinates. The extrapolation is described by a convection-type partial differential equation and implemented efficiently in the Fourier domain. Synthetic and field data experiments show that the proposed algorithm is able to detect accurate time-migration velocities by automatically measuring the flatness of events in dip-angle gathers.

  7. Group Velocity Engineering of Confined Ultrafast Magnons

    Science.gov (United States)

    Chen, Y.-J.; Zakeri, Kh.; Ernst, A.; Qin, H. J.; Meng, Y.; Kirschner, J.

    2017-12-01

    Quantum confinement permits the existence of multiple terahertz magnon modes in atomically engineered ultrathin magnetic films and multilayers. By means of spin-polarized high-resolution electron energy-loss spectroscopy, we report on the direct experimental detection of all exchange-dominated terahertz confined magnon modes in a 3 ML Co film. We demonstrate that, by tuning the structural and magnetic properties of the Co film, through its epitaxial growth on different surfaces, e.g., Ir(001), Cu(001), and Pt(111), one can achieve entirely different in-plane magnon dispersions, characterized by positive and negative group velocities. Our first-principles calculations show that spin-dependent many-body correlation effects in Co films play an important role in the determination of the energies of confined magnon modes. Our results suggest a pathway towards the engineering of the group velocity of confined ultrafast magnons.

  8. New GNSS velocity field and preliminary velocity model for Ecuador

    Science.gov (United States)

    Luna-Ludeña, Marco P.; Staller, Alejandra; Gaspar-Escribano, Jorge M.; Belén Benito, M.

    2016-04-01

    In this work, we present a new preliminary velocity model of Ecuador based on the GNSS data of the REGME network (continuous monitoring GNSS network). To date, there is no velocity model available for the country. The only existing model in the zone is the regional model VEMOS2009 for South America and Caribbean (Drewes and Heidbach, 2012). This model was developed from the SIRGAS station positions, the velocities of the SIRGAS-CON stations, and several geodynamics projects performed in the region. Just two continuous GNSS (cGNSS) stations of Ecuador were taking into account in the VEMOS2009 model. The first continuous station of the REGME network was established in 2008. At present, it is composed by 32 continuous GNSS stations, covering the country. All the stations provided data during at least two years. We processed the data of the 32 GNSS stations of REGME for the 2008-2014 period, as well as 20 IGS stations in order to link to the global reference frame IGb08 (ITRF2008). GPS data were processed using Bernese 5.0 software (Dach et al., 2007). We obtained and analyzed the GNSS coordinate time series of the 32 REGME stations and we calculated the GPS-derived horizontal velocity field of the country. Velocities in ITRF2008 were transformed into a South American fixed reference frame, using the Euler pole calculated from 8 cGNSS stations throughout this plate. Our velocity field is consistent with the tectonics of the country and contributes to a better understanding of it. From the horizontal velocity field, we determined a preliminary model using the kriging geostatistical technique. To check the results we use the cross-validation method. The differences between the observed and estimated values range from ± 5 mm. This is a new velocity model obtained from GNSS data for Ecuador.

  9. Opportunities and pitfalls in surface-wave interpretation

    KAUST Repository

    Schuster, Gerard T.

    2017-01-21

    Many explorationists think of surface waves as the most damaging noise in land seismic data. Thus, much effort is spent in designing geophone arrays and filtering methods that attenuate these noisy events. It is now becoming apparent that surface waves can be a valuable ally in characterizing the near-surface geology. This review aims to find out how the interpreter can exploit some of the many opportunities available in surface waves recorded in land seismic data. For example, the dispersion curves associated with surface waves can be inverted to give the S-wave velocity tomogram, the common-offset gathers can reveal the presence of near-surface faults or velocity anomalies, and back-scattered surface waves can be migrated to detect the location of near-surface faults. However, the main limitation of surface waves is that they are typically sensitive to S-wave velocity variations no deeper than approximately half to one-third the dominant wavelength. For many exploration surveys, this limits the depth of investigation to be no deeper than approximately 0.5-1.0 km.

  10. A survey of 286 Virgo cluster galaxies at optical griz and near-IR H band: surface brightness profiles and bulge-disc decompositions

    Science.gov (United States)

    McDonald, Michael; Courteau, Stéphane; Tully, R. Brent; Roediger, Joel

    2011-07-01

    We present and g-, r-, i-, z- and H-band surface brightness profiles and bulge-disc decompositions for a morphologically broad sample of 286 Virgo Cluster Catalogue (VCC) galaxies. The H-band data come from a variety of sources including our survey of 171 VCC galaxies at the University of Hawaii (UH) 2.2-m telescope, Canada-France-Hawaii Telescope (CFHT) and United Kingdom Infrared Telescope (UKIRT), and another 115 galaxies from the Two Micron All Sky Survey (2MASS) and GOLDMine archives. The optical data for all 286 VCC galaxies were extracted from the Sloan Digital Sky Survey (SDSS) images. The H-band and the SDSS griz data were analysed in a homogeneous manner using our own software, yielding a consistent set of deep, multiband surface brightness profiles for each galaxy. Average surface brightness profiles per morphological bin were created in order to characterize the variety of galaxy light profiles across the Hubble sequence. The 1D bulge-disc decomposition parameters, as well as non-parametric galaxy measures, such as effective radius, effective surface brightness and light concentration, are presented for all 286 VCC galaxies in each of the five optical/near-infrared wavebands. The profile decompositions account for bulge and disc components, spiral arms, nucleus and atmospheric blurring. The Virgo spiral galaxy bulges typically have a Sérsic index n˜ 1, while elliptical galaxies prefer n˜ 2. No galaxy spheroid requires n > 3. The light profiles for 70 per cent of the Virgo elliptical galaxies reveal the presence of both a spheroid and disc component. A more in-depth discussion of the structural parameter trends can be found in McDonald, Courteau & Tully. The data provided here should serve as a base for studies of galaxy structure and stellar populations in the cluster environment. The galaxy light profiles and bulge-disc decomposition results are available at the Centre de Données astronomiques de Strasbourg (CDS; ) and the author's own website ().

  11. Herschel/HIFI spectral line survey of the Orion Bar. Temperature and density differentiation near the PDR surface

    Science.gov (United States)

    Nagy, Z.; Choi, Y.; Ossenkopf-Okada, V.; van der Tak, F. F. S.; Bergin, E. A.; Gerin, M.; Joblin, C.; Röllig, M.; Simon, R.; Stutzki, J.

    2017-03-01

    Context. Photon dominated regions (PDRs) are interfaces between the mainly ionized and mainly molecular material around young massive stars. Analysis of the physical and chemical structure of such regions traces the impact of far-ultraviolet radiation of young massive stars on their environment. Aims: We present results on the physical and chemical structure of the prototypical high UV-illumination edge-on Orion Bar PDR from an unbiased spectral line survey with a wide spectral coverage which includes lines of many important gas coolants such as [Cii], [Ci], and CO and other key molecules such as H2CO, H2O, HCN, HCO+, and SO. Methods: A spectral scan from 480-1250 GHz and 1410-1910 GHz at 1.1 MHz resolution was obtained by the HIFI instrument on board the Herschel Space Observatory. We obtained physical parameters for the observed molecules. For molecules with multiple transitions we used rotational diagrams to obtain excitation temperatures and column densities. For species with a single detected transition we used an optically thin LTE approximation. In the case of species with available collisional rates, we also performed a non-LTE analysis to obtain kinetic temperatures, H2 volume densities, and column densities. Results: About 120 lines corresponding to 29 molecules (including isotopologues) have been detected in the Herschel/HIFI line survey, including 11 transitions of CO, 7 transitions of 13CO, 6 transitions of C18O, 10 transitions of H2CO, and 6 transitions of H2O. The rotational temperatures are in the range between 22 and 146 K and the column densities are in the range between 1.8 × 1012 cm-2 and 4.5 × 1017 cm-2. For species with at least three detected transitions and available collisional excitation rates we derived a best fit kinetic temperature and H2 volume density. Most species trace kinetic temperatures in the range between 100 and 150 K and H2 volume densities in the range between 105 and 106 cm-3. The species with temperatures and

  12. Seismicity and Improved Velocity Structure in Kuwait

    Energy Technology Data Exchange (ETDEWEB)

    Gok, R M; Rodgers, A J; Al-Enezi, A

    2006-01-26

    The Kuwait National Seismic Network (KNSN) began operation in 1997 and consists of nine three-component stations (eight short-period and one broadband) and is operated by the Kuwait Institute for Scientific Research. Although the region is largely believed to be aseismic, considerable local seismicity is recorded by KNSN. Seismic events in Kuwait are clustered in two main groups, one in the south and another in the north. The KNSN station distribution is able to capture the southern cluster within the footprint of the network but the northern cluster is poorly covered. Events tend to occur at depths ranging from the free surface to about 20 km. Events in the northern cluster tend to be deeper than those in south, however this might be an artifact of the station coverage. We analyzed KNSN recordings of nearly 200 local events to improve understanding of seismic events and crustal structure in Kuwait, performing several analyses with increasing complexity. First, we obtained an optimized one-dimensional (1D) velocity model for the entire region using the reported KNSN arrival times and routine locations. The resulting model is consistent with a recently obtained model from the joint inversion of receiver functions and surface wave group velocities. Crustal structure is capped by the thick ({approx} 7 km) sedimentary rocks of the Arabian Platform underlain by normal velocities for stable continental crust. Our new model has a crustal thickness of 44 km, constrained by an independent study of receiver functions and surface wave group velocities by Pasyanos et al (2006). Locations and depths of events after relocation with the new model are broadly consistent with those reported by KISR, although a few events move more than a few kilometers. We then used a double-difference tomography technique (tomoDD) to jointly locate the events and estimate three-dimensional (3D) velocity structure. TomoDD is based on hypoDD relocation algorithm and it makes use of both absolute and

  13. Coupling liquids acoustic velocity effects on elastic metallic bioglass properties

    Science.gov (United States)

    Metiri, W.; Hadjoub, F.; Doghmane, A.; Hadjoub, Z.

    2009-11-01

    The effect of surface acoustic wave, SAW, velocities of coupling liquids on acoustical properties of several bulk metallic glasses, BMG, has been investigated using simulation program based on acoustic microscopy. Thus, we determined variations of critical angles at which the excitation of longitudinal mode, θL and Rayleigh mode, θR occurs as a function of wave velocities in different coupling liquids, Vliq. Linear relations of the form θi =ai0 +βiVliq were deduced. The importance of such formula, used with Snell's law, lies in the direct determination of SAW velocities and consequently mechanical properties of BMGs.

  14. Superconducting spoke cavities for high-velocity applications

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, Christopher S. [Old Dominion U.; Delayen, Jean R. [Old Dominion U., JLAB

    2013-10-01

    To date, superconducting spoke cavities have been designed, developed, and tested for particle velocities up to {beta}{sub 0}~0.6, but there is a growing interest in possible applications of multispoke cavities for high-velocity applications. We have explored the design parameter space for low-frequency, high-velocity, double-spoke superconducting cavities in order to determine how each design parameter affects the electromagnetic properties, in particular the surface electromagnetic fields and the shunt impedance. We present detailed design for cavities operating at 325 and 352 MHz and optimized for {beta}{sub 0}~=0.82 and 1.

  15. The sloan lens acs survey. II. Stellar populations and internal structure of early-type lens galaxies

    NARCIS (Netherlands)

    Treu, Tommaso; Koopmans, Léon V.; Bolton, Adam S.; Burles, Scott; Moustakas, Leonidas A.

    2006-01-01

    We use HST images to derive effective radii and effective surface brightnesses of 15 early-type (E+S0) lens galaxies identified by the SLACS Survey. Our measurements are combined with stellar velocity dispersions from the SDSS database to investigate for the first time the distribution of lens

  16. DGSAT: Dwarf Galaxy Survey with Amateur Telescopes. II. A catalogue of isolated nearby edge-on disk galaxies and the discovery of new low surface brightness systems

    Science.gov (United States)

    Henkel, C.; Javanmardi, B.; Martínez-Delgado, D.; Kroupa, P.; Teuwen, K.

    2017-07-01

    The connection between the bulge mass or bulge luminosity in disk galaxies and the number, spatial and phase space distribution of associated dwarf galaxies is a discriminator between cosmological simulations related to galaxy formation in cold dark matter and generalised gravity models. Here, a nearby sample of isolated Milky Way-class edge-on galaxies is introduced, to facilitate observational campaigns to detect the associated families of dwarf galaxies at low surface brightness. Three galaxy pairs with at least one of the targets being edge-on are also introduced. Approximately 60% of the catalogued isolated galaxies contain bulges of different size, while the remaining objects appear to be bulgeless. Deep images of NGC 3669 (small bulge, with NGC 3625 at the edge of the image) and NGC 7814 (prominent bulge), obtained with a 0.4 m aperture, are also presented, resulting in the discovery of two new dwarf galaxy candidates, NGC 3669-DGSAT-3 and NGC 7814-DGSAT-7. Eleven additional low surface brightness galaxies are identified, previously notified with low quality measurement flags in the Sloan Digital Sky Survey (SDSS). Integrated magnitudes, surface brightnesses, effective radii, Sersic indices, axis ratios, and projected distances to their putative major hosts are displayed. At least one of the galaxies, NGC 3625-DGSAT-4, belongs with a surface brightness of μr ≈ 26 mag arcsec-2 and effective radius >1.5 kpc to the class of ultra-diffuse galaxies (UDGs). NGC 3669-DGSAT-3, the galaxy with the lowest surface brightness in our sample, may also be an UDG.

  17. A survey of state-of-the-art surface chemistries to minimize fouling from human and animal biofluids.

    Science.gov (United States)

    Blaszykowski, Christophe; Sheikh, Sonia; Thompson, Michael

    2015-10-15

    Upon contact with bodily fluids, synthetic materials spontaneously acquire a layer of various species (most notably proteins) on their surface. The concern with respect to biomedical equipment, implants or devices resides in the possibility for biological processes with potentially harmful effects to ensue. In biosensor technology, the issue with this natural fouling phenomenon is that of non-specific adsorption to sensing platforms, which generates an often overwhelming interference signal that prevents the detection, not to mention the quantification, of target analytes present at considerably lower concentration. To alleviate this ubiquitous, recurrent problem - this genuine biotechnological plague - considerable research efforts have been devoted over the last few decades to engineer antifouling coatings. Extensive literature now exists that describes stealth organic adlayers capable of reducing fouling surface coverage Γ down to a few ng cm(-2)- however from biotechnologically irrelevant buffered solutions free or nearly depleted of any potentially interfering species. Regrettably indeed, few coatings are known to display/retain such level of performance when exposed to otherwise more complex, real-life biosamples (even diluted). Herein, we comprehensively review the state-of-the-art surface chemistries developed to date (January 2015) to minimize fouling from 8 such uncomparatively more challenging biological media (blood plasma, blood serum, cell lysate, cerebrospinal fluid, egg, milk, saliva, and urine) - whether of human or animal origin. Literature search for another 25 biological milieux generated no (exploitable) hit. Also discussed in this Review are the identification of the species responsible for fouling, and the dependence of antifouling properties on biosample source variability.

  18. Introduction to vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Udesen, Jesper; Hansen, Kristoffer Lindskov

    over the full region of interest and a real time image at a frame rate of 20 Hz can be displayed. Real time videos have been obtained from both our research systems and from commercial BK Medical scanners. The vector velocity images reveal the full complexity of the human blood flow. It is easy to see...... direction and the correct velocity magnitude for any orientation of the vessels. At complex geometries like bifurcations, branching and for valves the approach reveals how the velocity changes magnitude and direction over the cardiac cycle. Vector velocity reveals a wealth of new information that now...... is accessible to the ultrasound community. The displaying and studying of this information is challenging as complex flow changes rapidly over the cardiac cycle....

  19. Kriging interpolating cosmic velocity field

    Science.gov (United States)

    Yu, Yu; Zhang, Jun; Jing, Yipeng; Zhang, Pengjie

    2015-10-01

    Volume-weighted statistics of large-scale peculiar velocity is preferred by peculiar velocity cosmology, since it is free of the uncertainties of galaxy density bias entangled in observed number density-weighted statistics. However, measuring the volume-weighted velocity statistics from galaxy (halo/simulation particle) velocity data is challenging. Therefore, the exploration of velocity assignment methods with well-controlled sampling artifacts is of great importance. For the first time, we apply the Kriging interpolation to obtain the volume-weighted velocity field. Kriging is a minimum variance estimator. It predicts the most likely velocity for each place based on the velocity at other places. We test the performance of Kriging quantified by the E-mode velocity power spectrum from simulations. Dependences on the variogram prior used in Kriging, the number nk of the nearby particles to interpolate, and the density nP of the observed sample are investigated. First, we find that Kriging induces 1% and 3% systematics at k ˜0.1 h Mpc-1 when nP˜6 ×1 0-2(h-1 Mpc )-3 and nP˜6 ×1 0-3(h-1 Mpc )-3 , respectively. The deviation increases for decreasing nP and increasing k . When nP≲6 ×1 0-4(h-1 Mpc )-3 , a smoothing effect dominates small scales, causing significant underestimation of the velocity power spectrum. Second, increasing nk helps to recover small-scale power. However, for nP≲6 ×1 0-4(h-1 Mpc )-3 cases, the recovery is limited. Finally, Kriging is more sensitive to the variogram prior for a lower sample density. The most straightforward application of Kriging on the cosmic velocity field does not show obvious advantages over the nearest-particle method [Y. Zheng, P. Zhang, Y. Jing, W. Lin, and J. Pan, Phys. Rev. D 88, 103510 (2013)] and could not be directly applied to cosmology so far. However, whether potential improvements may be achieved by more delicate versions of Kriging is worth further investigation.

  20. Determination of pharmaceuticals, personal care products, and pesticides in surface and treated waters: method development and survey.

    Science.gov (United States)

    Caldas, Sergiane Souza; Bolzan, Cátia Marian; Guilherme, Juliana Rocha; Silveira, Maria Angelis Kisner; Escarrone, Ana Laura Venquiaruti; Primel, Ednei Gilberto

    2013-08-01

    Water is fundamental to the existence of life since it is essential to a series of activities, such as agriculture, power generation, and public and industrial supplies. The residual water generated by these activities is released into the environment, reaches the water systems, and becomes a potential risk to nontarget organisms. This paper reports the development and validation of a quantitative method, based on solid-phase extraction and liquid chromatography tandem mass spectrometry, for the simultaneous analysis of 18 pharmaceuticals and personal care products (PPCPs) and 33 pesticides in surface and drinking waters. The accuracy of the method was determined by calculating the recoveries, which ranged from 70 to 120 % for most pesticides and PPCPs, whereas limits of quantification ranged from 0.8 to 40 ng/L. After the validation step, the method was applied to drinking and surface waters. Pesticides and PPCPs were found in concentrations lower than 135.5 ng/L. The evaluation of different water sources with regard to contamination by pesticides and PPCPs has been quite poor in southern Brazil.

  1. Online Wavelet Complementary velocity Estimator.

    Science.gov (United States)

    Righettini, Paolo; Strada, Roberto; KhademOlama, Ehsan; Valilou, Shirin

    2018-01-02

    In this paper, we have proposed a new online Wavelet Complementary velocity Estimator (WCE) over position and acceleration data gathered from an electro hydraulic servo shaking table. This is a batch estimator type that is based on the wavelet filter banks which extract the high and low resolution of data. The proposed complementary estimator combines these two resolutions of velocities which acquired from numerical differentiation and integration of the position and acceleration sensors by considering a fixed moving horizon window as input to wavelet filter. Because of using wavelet filters, it can be implemented in a parallel procedure. By this method the numerical velocity is estimated without having high noise of differentiators, integration drifting bias and with less delay which is suitable for active vibration control in high precision Mechatronics systems by Direct Velocity Feedback (DVF) methods. This method allows us to make velocity sensors with less mechanically moving parts which makes it suitable for fast miniature structures. We have compared this method with Kalman and Butterworth filters over stability, delay and benchmarked them by their long time velocity integration for getting back the initial position data. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  2. Characterization of solid surfaces

    National Research Council Canada - National Science Library

    Kane, Philip F; Larrabee, Graydon B

    1974-01-01

    .... A comprehensive review of surface analysis, this important volume surveys both principles and techniques of surface characterization, describes instrumentation, and suggests the course of future research...

  3. Estimation of real ship propelling performance by the surface velocity lattice method using model ship flow field data; Mokeisen ryujo data wo mochiita hyomen uzu koshiho ni yoru jissen suishin seino no suitei

    Energy Technology Data Exchange (ETDEWEB)

    Kai, H.; Ikehata, M.; Sakai, S. [Yokohama National University, Yokohama (Japan). Faculty of Engineering

    1997-10-01

    This is basically a technique wherein the wing element method is replaced by a surface vortex lattice method. A horseshoe vortex of unknown intensity and source surface of known intensity are distributed on the wing surface and, under conditions that the fluid will not cross the boundary, the intensity of horseshoe vortex circulation is calculated for the solution of the fluid field. For the simulation of a real ship in navigation, the required propeller revolution thrust is determined using the real ship resistance value and real ship thrust reduction factor estimated from a model ship resistance test by extrapolation. The calculation of propeller performance is conducted in the quasi-steady condition using the force of fluid working on one wing for each wing angle (with the wing rotated at the increment of 6 degrees), and the thrust and torque are determined using the averages of values obtained in one cycle. It is found that the torque value is overestimated in a considerable degree in the wing element theory. In the surface vortex lattice method, both thrust and torque values agree with experimental values mostly, and this method is found to be accurate enough as a navigation element calculation tool when many panels are considered. 4 refs., 5 figs., 1 tab.

  4. Planialtimetric Accuracy Evaluation of Digital Surface Model (dsm) and Digital Terrain Model (dtm) Obtained from Aerial Survey with LIDAR

    Science.gov (United States)

    Cruz, C. B. M.; Barros, R. S.; Rabaco, L. M. L.

    2012-07-01

    It's noticed a significant increase in the development of orbital and airborne sensors that enable the extraction of three-dimensional data. Consequently, it's important the increment of studies about the quality of altimetric values derived from these sensors to verify if the improvements implemented in the acquisition of data may influence the results. In this context, as part of a larger project that aims to evaluate the accuracy of various sensors, this work aims to analysis the planialtimetric accuracy of DSM and DTM generated from an aerial survey with LIDAR, using as reference for the planimetric analysis of the orthophotos obtained. The project was developed for an area of São Sebastião city, located in the basin of the North Coast of São Paulo state. The area's relief is very steep, with a predominance of dense forest vegetation, typical of the Atlantic Forest. All points have been established in the field, with the use of GNSS of one frequency (L1) through static relative positioning, acquiring a minimum of 1,500 epochs, for a distance less than 20 km to the base. In this work it's considered the Brazilian standard specifications for classification of cartographic bases (PEC). The Brazilian company responsible for the aerial survey (LACTEC) gave the following products for analysis: point clouds in raw format (x, y, z) using orthometric heights; point clouds (first and last pulse) for each range of flight to verify systematic errors; DTM uniformly spaced, filtering small natural obstacles, buildings and vegetation, in Geotiff format; DSM also uniformly spaced, in Geotiff format; and the mosaic of georeferenced digital images. The analysis realized on products from the LIDAR indicated their adoption to the scales 1:2,000 (Class A for the orthophotos and Class B for the DTM) and 1:5,000 (class C for the DSM). There were no indications of trends in the results. The average error was 0.01 m. It's important that new areas with different topographic

  5. Pierce Prize Lecture: High Velocity Clouds: Cosmological and Galactic Weather

    Science.gov (United States)

    Sembach, K.

    2001-12-01

    The Milky Way and its surrounding environs contain gas moving at high velocities with respect to the Sun. For the past half century, most of the information available for these high velocity clouds (HVCs) has come from H I 21cm surveys. Improvements in these surveys have recently led to the idea that some of the high velocity H I clouds may be located outside the Milky Way within the Local Group. Such a hypothesis is testable by various means, but the neutral gas content of the clouds tells only half of a much more complex story. In this talk I will present new information about the ionized gas within HVCs, their impact on the gaseous atmosphere of the Galaxy, and their relevance to the cosmic web of hot gas that may contain a significant fraction of the baryonic material in the low-redshift universe.

  6. RADIAL VELOCITY ECLIPSE MAPPING OF EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Nikolov, Nikolay; Sainsbury-Martinez, Felix, E-mail: nikolay@astro.ex.ac.uk [Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2015-07-20

    Planetary rotation rates and obliquities provide information regarding the history of planet formation, but have not yet been measured for evolved extrasolar planets. Here we investigate the theoretical and observational perspective of the Rossiter–McLaughlin effect during secondary eclipse (RMse) ingress and egress for transiting exoplanets. Near secondary eclipse, when the planet passes behind the parent star, the star sequentially obscures light from the approaching and receding parts of the rotating planetary surface. The temporal block of light emerging from the approaching (blueshifted) or receding (redshifted) parts of the planet causes a temporal distortion in the planet’s spectral line profiles resulting in an anomaly in the planet’s radial velocity curve. We demonstrate that the shape and the ratio of the ingress-to-egress radial velocity amplitudes depends on the planetary rotational rate, axial tilt, and impact factor (i.e., sky-projected planet spin–orbital alignment). In addition, line asymmetries originating from different layers in the atmosphere of the planet could provide information regarding zonal atmospheric winds and constraints on the hot spot shape for giant irradiated exoplanets. The effect is expected to be most-pronounced at near-infrared wavelengths, where the planet-to-star contrasts are large. We create synthetic near-infrared, high-dispersion spectroscopic data and demonstrate how the sky-projected spin axis orientation and equatorial velocity of the planet can be estimated. We conclude that the RMse effect could be a powerful method to measure exoplanet spins.

  7. The Radial Velocity Experiment (RAVE): Fifth Data Release

    NARCIS (Netherlands)

    Kunder, Andrea; Kordopatis, Georges; Steinmetz, Matthias; Zwitter, Tomaž; McMillan, Paul J.; Casagrande, Luca; Enke, Harry; Wojno, Jennifer; Valentini, Marica; Chiappini, Cristina; Matijevič, Gal; Siviero, Alessandro; de Laverny, Patrick; Recio-Blanco, Alejandra; Bijaoui, Albert; Wyse, Rosemary F. G.; Binney, James; Grebel, E. K.; Helmi, Amina; Jofre, Paula; Antoja, Teresa; Gilmore, Gerard; Siebert, Arnaud; Famaey, Benoit; Bienaymé, Olivier; Gibson, Brad K.; Freeman, Kenneth C.; Navarro, Julio F.; Munari, Ulisse; Seabroke, George; Anguiano, Borja; Žerjal, Maruša; Minchev, Ivan; Reid, Warren; Bland-Hawthorn, Joss; Kos, Janez; Sharma, Sanjib; Watson, Fred; Parker, Quentin A.; Scholz, Ralf-Dieter; Burton, Donna; Cass, Paul; Hartley, Malcolm; Fiegert, Kristin; Stupar, Milorad; Ritter, Andreas; Hawkins, Keith; Gerhard, Ortwin; Chaplin, W. J.; Davies, G. R.; Elsworth, Y. P.; Lund, M. N.; Miglio, A.; Mosser, B.

    2017-01-01

    Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is the fifth data release from a magnitude-limited (9survey of stars randomly selected in the Southern Hemisphere. The RAVE medium-resolution spectra (R˜ 7500) covering the Ca-triplet region (8410-8795 Å) span the complete time

  8. Gait phase varies over velocities.

    Science.gov (United States)

    Liu, Yancheng; Lu, Kun; Yan, Songhua; Sun, Ming; Lester, D Kevin; Zhang, Kuan

    2014-02-01

    We sought to characterize the percent (PT) of the phases of a gait cycle (GC) as velocity changes to establish norms for pathological gait characteristics with higher resolution technology. Ninety five healthy subjects (49 males and 46 females with age 34.9 ± 11.8 yrs, body weight 64.0 ± 11.7 kg and BMI 23.5 ± 3.6) were enrolled and walked comfortably on a 10-m walkway at self-selected slower, normal, and faster velocities. Walking was recorded with a high speed camera (250 frames per second) and the eight phases of a GC were determined by examination of individual frames for each subject. The correlation coefficients between the mean PT of the phases of the three velocities gaits and PT defined by previous publications were all greater than 0.99. The correlation coefficient between velocity and PT of gait phases is -0.83 for loading response (LR), -0.75 for mid stance (MSt), and -0.84 for pre-swing (PSw). While the PT of the phases of three velocities from this study are highly correlated with PT described by Dr. Jacquenlin Perry decades ago, actual PT of each phase varied amongst these individuals with the largest coefficient variation of 24.31% for IC with slower velocity. From slower to faster walk, the mean PT of MSt diminished from 35.30% to 25.33%. High resolution recording revealed ambiguity of some gait phase definitions, and these data may benefit GC characterization of normal and pathological gait in clinical practice. The study results indicate that one should consider individual variations and walking velocity when evaluating gaits of subjects using standard gait phase classification. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Laboratory Evaluation of Aggregate Polishing as a function of Load and Velocity : Application to the Prediction of Damages on Skid Resistance of Pavement Surface due to Trucks and Passenger Cars

    OpenAIRE

    KANE, Malal; ZHAO, Dan; DE LARRARD, François; DO, Minh Tan

    2012-01-01

    Skid resistance of road surfaces depends mostly on pavement texture. This texture is usually divided to two components:microtexture and macrotexture. Microtexture refers to the smallscale texture of the road aggregate component while macrotexture refers to the large-scale texture of the road as a whole due to the aggregate particle arrangement. Both components contribute to the generation of friction between tyre and road. However, due to traffic, the firstcited component is continuously poli...

  10. Preliminary inter-model comparison of the Agulhas current with direct range doppler velocity estimates from Envisat's Advanced Synthetic Aperture Radar (ASAR)

    CSIR Research Space (South Africa)

    Backeberg, Bjorn C

    2010-07-01

    Full Text Available is of great importance. In this paper we compare direct surface velocity estimates from Envisat's Advanced Synthetic Aperture Radar with surface velocity fields obtained from two different ocean numerical models. In particular, we focus on the models...

  11. Corrosion and biofouling on the non-heat-exchanger surfaces of an ocean thermal energy conversion power plant: a survey

    Energy Technology Data Exchange (ETDEWEB)

    Castelli, V.J. (ed.)

    1979-05-01

    Of the many foreseeable problems confronting economical ocean thermal energy conversion operation, two major items are the deterioration of the structural and functional components, which prevents efficient operation, and the biofouling of the surfaces, which adds excess weight to the floating ocean platform. The techniques required for effective long-term control of deterioration and corrosion have been investigated actively for many years, and successful solutions for most situations have been developed. For the most part, these solutions can be directly transferred to the ocean thermal energy conversion plant. The majority of problems in these areas are expected to be associated with scale-up and will require some advanced development due to the immensity of the ocean thermal energy conversion platform. Current antifouling control systems are not effective for long-term fouling prevention. Commercially available antifouling coatings are limited to a 3-year service life in temperate waters, and even shorter in tropical waters. However, underwater cleaning techniques and some fouling-control systems presently being used by conventional power plants may find utility on an ocean thermal energy conversion plant. In addition, some recent major advances in long-term antifouling coatings sponsored by the Navy may be applicable to ocean thermal energy conversion. 132 references.

  12. HF Radar Observation of Velocity Fields Induced by Tsunami Waves in the Kii Channel, Japan

    OpenAIRE

    日向, 博文; 藤, 良太郎; 藤井, 智史; 藤田, 裕一; 花土, 弘; 片岡, 智哉; 水谷, 雅裕; 高橋, 智幸

    2012-01-01

    High frequency ocean surface radar observation reveals the velocity fields of propagating tsunami waves and subsequent 30-40 minute period natural oscillation in the Kii Channel, Japan induced by the March 11, 2011 moment magnitude 9.0 Tohoku-Oki earthquake. Technical issues of the ocean surface radar sysytem concerning the detection of tsunami waves and natural oscillation velocities are also discussed.

  13. The exploration technology and application of sea surface wave

    Science.gov (United States)

    Wang, Y.

    2016-12-01

    In order to investigate the seismic velocity structure of the shallow sediments in the Bohai Sea of China, we conduct a shear-wave velocity inversion of the surface wave dispersion data from a survey of 12 ocean bottom seismometers (OBS) and 377 shots of a 9000 inch3 air gun. With OBS station spacing of 5 km and air gun shot spacing of 190 m, high-quality Rayleigh wave data were recorded by the OBSs within 0.4 5 km offset. Rayleigh wave phase velocity dispersion for the fundamental mode and first overtone in the frequency band of 0.9 3.0 Hz were retrieved with the phase-shift method and inverted for the shear-wave velocity structure of the shallow sediments with a damped iterative least-square algorithm. Pseudo 2-D shear-wave velocity profiles with depth to 400 m show coherent features of relatively weak lateral velocity variation. The uncertainty in shear-wave velocity structure was also estimated based on the pseudo 2-D profiles from 6 trial inversions with different initial models, which suggest a velocity uncertainty < 30 m/s for most parts of the 2-D profiles. The layered structure with little lateral variation may be attributable to the continuous sedimentary environment in the Cenozoic sedimentary basin of the Bohai Bay basin. The shear-wave velocity of 200 300 m/s in the top 100 m of the Bohai Sea floor may provide important information for offshore site response studies in earthquake engineering. Furthermore, the very low shear-wave velocity structure (200 700 m/s) down to 400 m depth could produce a significant travel time delay of 1 s in the S wave arrivals, which needs to be considered to avoid serious bias in S wave traveltime tomographic models.

  14. Signal velocity in oscillator arrays

    Science.gov (United States)

    Cantos, C. E.; Veerman, J. J. P.; Hammond, D. K.

    2016-09-01

    We investigate a system of coupled oscillators on the circle, which arises from a simple model for behavior of large numbers of autonomous vehicles where the acceleration of each vehicle depends on the relative positions and velocities between itself and a set of local neighbors. After describing necessary and sufficient conditions for asymptotic stability, we derive expressions for the phase velocity of propagation of disturbances in velocity through this system. We show that the high frequencies exhibit damping, which implies existence of well-defined signal velocitiesc+ > 0 and c- < 0 such that low frequency disturbances travel through the flock as f+(x - c+t) in the direction of increasing agent numbers and f-(x - c-t) in the other.

  15. The effect of peculiar velocities on supernova cosmology

    DEFF Research Database (Denmark)

    Davis, Tamara Maree; Hui, Lam; Frieman, Joshua A.

    2011-01-01

    We analyze the effect that peculiar velocities have on the cosmological inferences we make using luminosity distance indicators, such as Type Ia supernovae. In particular we study the corrections required to account for (1) our own motion, (2) correlations in galaxy motions, and (3) a possible...... local under- or overdensity. For all of these effects we present a case study showing the impact on the cosmology derived by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SN Survey). Correcting supernova (SN) redshifts for the cosmic microwave background (CMB) dipole slightly overcorrects...

  16. Angle independent velocity spectrum determination

    DEFF Research Database (Denmark)

    2014-01-01

    An ultrasound imaging system (100) includes a transducer array (102) that emits an ultrasound beam and produces at least one transverse pulse-echo field that oscillates in a direction transverse to the emitted ultrasound beam and that receive echoes produced in response thereto and a spectral vel...... velocity estimator (110) that determines a velocity spectrum for flowing structure, which flows at an angle of 90 degrees and flows at angles less than 90 degrees with respect to the emitted ultrasound beam, based on the received echoes....

  17. Scientific Objectives of Small Carry-on Impactor (SCI) and Deployable Camera 3 Digital (DCAM3-D): Observation of an Ejecta Curtain and a Crater Formed on the Surface of Ryugu by an Artificial High-Velocity Impact

    Science.gov (United States)

    Arakawa, M.; Wada, K.; Saiki, T.; Kadono, T.; Takagi, Y.; Shirai, K.; Okamoto, C.; Yano, H.; Hayakawa, M.; Nakazawa, S.; Hirata, N.; Kobayashi, M.; Michel, P.; Jutzi, M.; Imamura, H.; Ogawa, K.; Sakatani, N.; Iijima, Y.; Honda, R.; Ishibashi, K.; Hayakawa, H.; Sawada, H.

    2017-07-01

    The Small Carry-on Impactor (SCI) equipped on Hayabusa2 was developed to produce an artificial impact crater on the primitive Near-Earth Asteroid (NEA) 162173 Ryugu (Ryugu) in order to explore the asteroid subsurface material unaffected by space weathering and thermal alteration by solar radiation. An exposed fresh surface by the impactor and/or the ejecta deposit excavated from the crater will be observed by remote sensing instruments, and a subsurface fresh sample of the asteroid will be collected there. The SCI impact experiment will be observed by a Deployable CAMera 3-D (DCAM3-D) at a distance of ˜1 km from the impact point, and the time evolution of the ejecta curtain will be observed by this camera to confirm the impact point on the asteroid surface. As a result of the observation of the ejecta curtain by DCAM3-D and the crater morphology by onboard cameras, the subsurface structure and the physical properties of the constituting materials will be derived from crater scaling laws. Moreover, the SCI experiment on Ryugu gives us a precious opportunity to clarify effects of microgravity on the cratering process and to validate numerical simulations and models of the cratering process.

  18. Intensive archaeological survey of the F/H Surface Enhancement Project Area, Savannah River Site, Aiken and Barnwell Counties, South Carolina

    Energy Technology Data Exchange (ETDEWEB)

    Sassaman, K.E.; Gillam, J.C.

    1993-08-01

    Twelve archaeological sites and four artifact occurrences were located by intensive survey of two tracts of land for the F and H Surface Enhancement Project on the Savannah River Site, Aiken and Barnwell Counties, South Carolina. Fieldwork in the 480-acre project area included surface reconnaissance of 3.6 linear kilometers of transects, 140 shovel tests along 4.2 linear kilometers of transects, an additional 162 shovel tests at sites and occurrences, and the excavation of six l {times} 2 m test units. All but one of the sites contained artifacts of the prehistoric era; the twelfth site consists of the remains of a twentieth-century home place. The historic site and six of the prehistoric sites consist of limited and/or disturbed contexts of archaeological deposits that have little research potential and are therefore considered ineligible for nomination to the National Register of Historic Places (NRHP). The remaining five sites have sufficient content and integrity to yield information important to ongoing investigations into upland site use. These sites (38AK146, 38AK535, 38AK539, 38AK541, and 38AK543) are thus deemed eligible for nomination to the NRHP and the Savannah River Archaeological Research Program (SRARP) recommends that they be preserved through avoidance or data recovery.

  19. Survey mirrors and lenses and their required surface accuracy. Volume 1. Technical report. Final report for September 15, 1978-December 1, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Beesing, M. E.; Buchholz, R. L.; Evans, R. A.; Jaminski, R. W.; Mathur, A. K.; Rausch, R. A.; Scarborough, S.; Smith, G. A.; Waldhauer, D. J.

    1980-01-01

    An investigation of the optical performance of a variety of concentrating solar collectors is reported. The study addresses two important issues: the accuracy of reflective or refractive surfaces required to achieve specified performance goals, and the effect of environmental exposure on the performance concentrators. To assess the importance of surface accuracy on optical performance, 11 tracking and nontracking concentrator designs were selected for detailed evaluation. Mathematical models were developed for each design and incorporated into a Monte Carlo ray trace computer program to carry out detailed calculations. Results for the 11 concentrators are presented in graphic form. The models and computer program are provided along with a user's manual. A survey data base was established on the effect of environmental exposure on the optical degradation of mirrors and lenses. Information on environmental and maintenance effects was found to be insufficient to permit specific recommendations for operating and maintenance procedures, but the available information is compiled and reported and does contain procedures that other workers have found useful.

  20. Documentation of the Surface-Water Routing (SWR1) Process for modeling surface-water flow with the U.S. Geological Survey Modular Ground-Water Model (MODFLOW-2005)

    Science.gov (United States)

    Hughes, Joseph D.; Langevin, Christian D.; Chartier, Kevin L.; White, Jeremy T.

    2012-01-01

    A flexible Surface-Water Routing (SWR1) Process that solves the continuity equation for one-dimensional and two-dimensional surface-water flow routing has been developed for the U.S. Geological Survey three-dimensional groundwater model, MODFLOW-2005. Simple level- and tilted-pool reservoir routing and a diffusive-wave approximation of the Saint-Venant equations have been implemented. Both methods can be implemented in the same model and the solution method can be simplified to represent constant-stage elements that are functionally equivalent to the standard MODFLOW River or Drain Package boundary conditions. A generic approach has been used to represent surface-water features (reaches) and allows implementation of a variety of geometric forms. One-dimensional geometric forms include rectangular, trapezoidal, and irregular cross section reaches to simulate one-dimensional surface-water features, such as canals and streams. Two-dimensional geometric forms include reaches defined using specified stage-volume-area-perimeter (SVAP) tables and reaches covering entire finite-difference grid cells to simulate two-dimensional surface-water features, such as wetlands and lakes. Specified SVAP tables can be used to represent reaches that are smaller than the finite-difference grid cell (for example, isolated lakes), or reaches that cannot be represented accurately using the defined top of the model. Specified lateral flows (which can represent point and distributed flows) and stage-dependent rainfall and evaporation can be applied to each reach. The SWR1 Process can be used with the MODFLOW Unsaturated Zone Flow (UZF1) Package to permit dynamic simulation of runoff from the land surface to specified reaches. Surface-water/groundwater interactions in the SWR1 Process are mathematically defined to be a function of the difference between simulated stages and groundwater levels, and the specific form of the reach conductance equation used in each reach. Conductance can be

  1. Patch near field acoustic holography based on particle velocity measurements

    DEFF Research Database (Denmark)

    Zhang, Yong-Bin; Jacobsen, Finn; Bi, Chuan-Xing

    2009-01-01

    Patch near field acoustic holography (PNAH) based on sound pressure measurements makes it possible to reconstruct the source field near a source by measuring the sound pressure at positions on a surface. that is comparable in size to the source region of concern. Particle velocity is an alternative...... input quantity for NAH, and the advantage of using the normal component of the particle velocity rather than the sound pressure as the input of conventional spatial Fourier transform based NAH and as the input of the statistically optimized variant of NAH has recently been demonstrated. This paper......, PNAH based on particle velocity measurements can give better results than the pressure-based PNAH with a reduced number of iterations. A simulation study, as well as an experiment carried out with a pressure-velocity sound intensity probe, demonstrates these findings....

  2. Seismic surveys test on Innerhytta Pingo, Adventdalen, Svalbard Islands

    Science.gov (United States)

    Boaga, Jacopo; Rossi, Giuliana; Petronio, Lorenzo; Accaino, Flavio; Romeo, Roberto; Wheeler, Walter

    2015-04-01

    We present the preliminary results of an experimental full-wave seismic survey test conducted on the Innnerhytta a Pingo, located in the Adventdalen, Svalbard Islands, Norway. Several seismic surveys were adopted in order to study a Pingo inner structure, from classical reflection/refraction arrays to seismic tomography and surface waves analysis. The aim of the project IMPERVIA, funded by Italian PNRA, was the evaluation of the permafrost characteristics beneath this open-system Pingo by the use of seismic investigation, evaluating the best practice in terms of logistic deployment. The survey was done in April-May 2014: we collected 3 seismic lines with different spacing between receivers (from 2.5m to 5m), for a total length of more than 1 km. We collected data with different vertical geophones (with natural frequency of 4.5 Hz and 14 Hz) as well as with a seismic snow-streamer. We tested different seismic sources (hammer, seismic gun, fire crackers and heavy weight drop), and we verified accurately geophone coupling in order to evaluate the different responses. In such peculiar conditions we noted as fire-crackers allow the best signal to noise ratio for refraction/reflection surveys. To ensure the best geophones coupling with the frozen soil, we dug snow pits, to remove the snow-cover effect. On the other hand, for the surface wave methods, the very high velocity of the permafrost strongly limits the generation of long wavelengths both with these explosive sources as with the common sledgehammer. The only source capable of generating low frequencies was a heavy drop weight system, which allows to analyze surface wave dispersion below 10 Hz. Preliminary data analysis results evidence marked velocity inversions and strong velocity contrasts in depth. The combined use of surface and body waves highlights the presence of a heterogeneous soil deposit level beneath a thick layer of permafrost. This is the level that hosts the water circulation from depth controlling

  3. Crustal velocities from geodetic very long baseline interferometry

    Science.gov (United States)

    Fallon, F. W.; Dillinger, W. H.

    1992-05-01

    VLBI observations from the International Radio Interferometric Surveying and Crustal Dynamics Projects programs taken over a span of 5-8 yr (through August 1990) are used to derive relative velocities of 16 sites on the North American, Eurasian, Pacific, and African plates. The data reduction scheme simultaneously estimates earth orientation parameters and nutation for each session, local atmosphere and clock correction terms, source positions, and initial site positions, as well as the site velocities. Instead of an a priori geophysical crustal model, a minimal set of geometric constraints is used to obtain the velocities. Two alternative constraint formulations - setting the secular motion of the pole and mean length of day to fixed values, and fixing the net rotation of the sites - are considered. They are shown to be equivalent in that they yield equivalent velocity sets with allowance for translation and rotation. The resulting velocities have formal standard errors typically less than 0.2 cm/yr, and most velocities are significantly different from zero.

  4. Accurate Recovery of H i Velocity Dispersion from Radio Interferometers

    Energy Technology Data Exchange (ETDEWEB)

    Ianjamasimanana, R. [Max-Planck Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Blok, W. J. G. de [Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo (Netherlands); Heald, George H., E-mail: roger@mpia.de, E-mail: blok@astron.nl, E-mail: George.Heald@csiro.au [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV, Groningen (Netherlands)

    2017-05-01

    Gas velocity dispersion measures the amount of disordered motion of a rotating disk. Accurate estimates of this parameter are of the utmost importance because the parameter is directly linked to disk stability and star formation. A global measure of the gas velocity dispersion can be inferred from the width of the atomic hydrogen (H i) 21 cm line. We explore how several systematic effects involved in the production of H i cubes affect the estimate of H i velocity dispersion. We do so by comparing the H i velocity dispersion derived from different types of data cubes provided by The H i Nearby Galaxy Survey. We find that residual-scaled cubes best recover the H i velocity dispersion, independent of the weighting scheme used and for a large range of signal-to-noise ratio. For H i observations, where the dirty beam is substantially different from a Gaussian, the velocity dispersion values are overestimated unless the cubes are cleaned close to (e.g., ∼1.5 times) the noise level.

  5. The dependence of sheet erosion velocity on slope angle

    Directory of Open Access Journals (Sweden)

    Chernyshev Sergey Nikolaevich

    2014-09-01

    Full Text Available The article presents a method for estimating the erosion velocity on forested natural area. As a research object for testing the methodology the authors selected Neskuchny Garden - a city Park on the Moskva river embankment, named after the cognominal Palace of Catherine's age. Here, an almost horizontal surface III of the Moskva river terrace above the flood-plain is especially remarkable, accentuated by the steep sides of the ravine parallel to St. Andrew's, but short and nameless. The crests of the ravine sides are sharp, which is the evidence of its recent formation, but the old trees on the slopes indicate that it has not been growing for at least 100 years. Earlier Russian researchers defined vertical velocity of sheet erosion for different regions and slopes with different parent (in relation to the soil rocks. The comparison of the velocities shows that climatic conditions, in the first approximation, do not have a decisive influence on the erosion velocity of silt loam soils. The velocities on the shores of Issyk-Kul lake and in Moscow proved to be the same. But the composition of the parent rocks strongly affects the sheet erosion velocity. Even low-strength rock material reduces the velocity by times. Phytoindication method gives a real, physically explainable sheet erosion velocities. The speed is rather small but it should be considered when designing long-term structures on the slopes composed of dispersive soils. On the slopes composed of rocky soils sheet erosion velocity is so insignificant that it shouldn't be taken into account when designing. However, there may be other geological processes, significantly disturbing the stability of slopes connected with cracks.

  6. The TEDI instrument for near-IR radial velocity surveys

    Science.gov (United States)

    Edelstein, Jerry; Erskine, David J.; Lloyd, James; Herter, Terry; Marckwordt, Mario; Feuerstein, Michael

    2006-06-01

    The TEDI (TripleSpec Externally Dispersed Interferometry) is an interferometric spectrometer that will be used to explore the population of planets around the lowest mass stars. The instrument, to be deployed on the Palomar 200 Cassegrain mount, includes a stabilized Michelson interferometer combined with a medium resolution, broad band (0.8 - 2.4 micron) spectrograph, TripleSpec. We describe the instrument design and its application to Doppler velocimetry and high-resolution spectroscopy.

  7. A survey of radial velocities in the zodiacal dust cloud

    CERN Document Server

    May, Brian Harold

    2008-01-01

    The Zodiacal Light, that misty diffuse cone of light seen in the West after Sunset and the East before Sunrise, is a beautiful and intriguing phenomenon. Even though everyone can enjoy the sight from a suitably dark location, it is poorly understood, and has been the subject of relatively little research. Brian May began his research into the subject in 1970, and was finally awarded his PhD in 2007, after a hiatus of more than 30 years pursuing his other career as guitarist with his rock band Queen. This book is Brian 's thesis, and as such presents the results of his research for astronomers.

  8. Assessing the Accuracy of High Resolution Digital Surface Models Computed by PhotoScan® and MicMac® in Sub-Optimal Survey Conditions

    Directory of Open Access Journals (Sweden)

    Marion Jaud

    2016-06-01

    Full Text Available For monitoring purposes and in the context of geomorphological research, Unmanned Aerial Vehicles (UAV appear to be a promising solution to provide multi-temporal Digital Surface Models (DSMs and orthophotographs. There are a variety of photogrammetric software tools available for UAV-based data. The objective of this study is to investigate the level of accuracy that can be achieved using two of these software tools: Agisoft PhotoScan® Pro and an open-source alternative, IGN© MicMac®, in sub-optimal survey conditions (rugged terrain, with a large variety of morphological features covering a range of roughness sizes, poor GPS reception. A set of UAV images has been taken by a hexacopter drone above the Rivière des Remparts, a river on Reunion Island. This site was chosen for its challenging survey conditions: the topography of the study area (i involved constraints on the flight plan; (ii implied errors on some GPS measurements; (iii prevented an optimal distribution of the Ground Control Points (GCPs and; (iv was very complex to reconstruct. Several image processing tests are performed with different scenarios in order to analyze the sensitivity of each software package to different parameters (image quality, numbers of GCPs, etc.. When computing the horizontal and vertical errors within a control region on a set of ground reference targets, both methods provide rather similar results. A precision up to 3–4 cm is achievable with these software packages. The DSM quality is also assessed over the entire study area comparing PhotoScan DSM and MicMac DSM with a Terrestrial Laser Scanner (TLS point cloud. PhotoScan and MicMac DSM are also compared at the scale of particular features. Both software packages provide satisfying results: PhotoScan is more straightforward to use but its source code is not open; MicMac is recommended for experimented users as it is more flexible.

  9. Detecting temporal change in land-surface altitude using robotic land-surveying techniques and geographic information system applications at an earthen dam site in Southern Westchester County, New York

    Science.gov (United States)

    Noll, Michael L.; Chu, Anthony

    2017-08-14

    In 2005, the U.S. Geological Survey began a cooperative study with New York City Department of Environmental Protection to characterize the local groundwater-flow system and identify potential sources of seeps on the southern embankment at the Hillview Reservoir in southern Westchester County, New York. Monthly site inspections at the reservoir indicated an approximately 90-square-foot depression in the land surface directly upslope from a seep that has episodically flowed since 2007. In July 2008, the U.S. Geological Survey surveyed the topography of land surface in this depression area by collecting high-accuracy (resolution less than 1 inch) measurements. A point of origin was established for the topographic survey by using differentially corrected positional data collected by a global navigation satellite system. Eleven points were surveyed along the edge of the depression area and at arbitrary locations within the depression area by using robotic land-surveying techniques. The points were surveyed again in March 2012 to evaluate temporal changes in land-surface altitude. Survey measurements of the depression area indicated that the land-surface altitude at 8 of the 11 points decreased beyond the accepted measurement uncertainty during the 44 months from July 2008 to March 2012. Two additional control points were established at stable locations along Hillview Avenue, which runs parallel to the embankment. These points were measured during the July 2008 survey and measured again during the March 2012 survey to evaluate the relative accuracy of the altitude measurements. The relative horizontal and vertical (altitude) accuracies of the 11 topographic measurements collected in March 2012 were ±0.098 and ±0.060 feet (ft), respectively. Changes in topography at 8 of the 11 points ranged from 0.09 to 0.63 ft and topography remained constant, or within the measurement uncertainty, for 3 of the 11 points.Two cross sections were constructed through the depression area

  10. A 3-mode, Variable Velocity Jet Model for HH 34

    Science.gov (United States)

    Raga, A.; Noriega-Crespo, A.

    1998-01-01

    Variable ejection velocity jet models can qualitatively explain the appearance of successive working surfaces in Herbig-Haro (HH) jets. This paper presents an attempt to explore which features of the HH 34 jet can indeed be reproduced by such a model.

  11. An optical velocity for the Phoenix dwarf galaxy

    NARCIS (Netherlands)

    Irwin, M; Tolstoy, E

    2002-01-01

    We present the results of a Very Large Telescope observing programme carried out in service mode using FORS1 on ANTU in long-slit mode to determine the optical velocities of nearby low surface brightness galaxies. As part of our programme of service observations we obtained long-slit spectra of

  12. Influence of compression pressure and velocity on tablet sticking.

    Science.gov (United States)

    Kakimi, Kazuyuki; Niwa, Toshiyuki; Danjo, Kazumi

    2010-12-01

    A rotary tablet machine fitted with 8-mm diameter flat-faced punches was used to measure scraper pressure (SCR), a type of shear stress, to evaluate sticking behavior. The shear stress between the surfaces of the tablet and lower punch was determined using an SCR detection system. Mean surface roughness (R(a)) of tablets, measured by a scanning laser-microscope, was used to estimate the magnitude of sticking. Tablet tensile strength tended to increase with compression pressure at either of the tablet production velocities tested, which was consistent with previous reports. SCR decreased with increasing compression pressure for samples at all compression velocities, and showed a tendency to increase with binder concentration. SCR also tended to increase with compression velocity for samples at all compression pressures, suggesting that the frequency of tablet sticking increased as compression velocity increased. R(a) associated with sticking increased with SCR, indicating that the adhesive force between the particles of the tablet surface and the lower punch surface plays an important role in sticking.

  13. Channel flow analysis. [velocity distribution throughout blade flow field

    Science.gov (United States)

    Katsanis, T.

    1973-01-01

    The design of a proper blade profile requires calculation of the blade row flow field in order to determine the velocities on the blade surfaces. An analysis theory is presented for several methods used for this calculation and associated computer programs that were developed are discussed.

  14. Advanced Ice Velocity Mapping Using Landsat 8

    Science.gov (United States)

    Klinger, M. J.; Scambos, T. A.; Fahnestock, M. A.; Haran, T. M.

    2014-12-01

    Improved image-to-image cross correlation software is applied to pairs of sequential Landsat 8 satellite imagery to accurately measure ice surface velocity over ice sheets and glaciers (±0.1 pixel displacement, 15 meter pixels). The high radiometric fidelity of Landsat 8's panchromatic band (12-bit), and exceptional geolocation accuracy (typically ±5 m) supports the generation of ice velocity fields over very short time intervals (e.g., 16-, 32-, or 48-day repeat images of the same scene location). The high radiometry supports velocity mapping in areas with very subtle topographic detail, including un-crevassed sastrugi regions on ice dome flanks or the ice sheet interior. New Python-based software presently under development (named PyCorr), takes two sequential Landsat 8 OLI scenes (or suitably processed ETM+ or TM scenes) and matches small sub-scenes ('chips') between the images based on similarity in their gray-scale value patterns, using an image correlation algorithm. Peak fitting in the region of maximum correlation for a chip pair yields sub-pixel fits to the feature offset vector. Vector editing after the image correlation runs seeks to eliminate spurious and cloud-impacted vectors, and correct residual geo-location error. This processing is based on plausible values of ice strain rates and known areas of near-zero ice flow (rock outcrops, ice dome areas, etc.). In preliminary processing, we have examined ~800 Landsat 8 image pairs having <20% cloud cover spanning the near-coastal Antarctic ice sheet during the 2013-14 summer season.

  15. Evaluation and use of U.S. Environmental Protection Agency Clean Watersheds Needs Survey data to quantify nutrient loads to surface water, 1978–2012

    Science.gov (United States)

    Ivahnenko, Tamara

    2017-12-07

    Changes in municipal and industrial point-source discharges over time have been an important factor affecting nutrient trends in many of the Nation’s streams and rivers. This report documents how three U.S. Environmental Protection Agency (EPA) national datasets—the Permit Compliance System, the Integrated Compliance Information System, and the Clean Watersheds Needs Survey—were evaluated for use in the U.S. Geological Survey National Water-Quality Assessment project to assess the causes of nutrient trends. This report also describes how a database of total nitrogen load and total phosphorous load was generated for select wastewater treatment facilities in the United States based on information reported in the EPA Clean Watersheds Needs Survey. Nutrient loads were calculated for the years 1978, 1980, 1982, 1984, 1986, 1988, 1990, 1992, 1996, 2000, 2004, 2008, and 2012 based on average nitrogen and phosphorous concentrations for reported treatment levels and on annual reported flow values.The EPA Permit Compliance System (PCS) and Integrated Compliance Information System (ICIS), which monitor point-source facility discharges, together are the Nation’s most spatially comprehensive dataset for nutrients released to surface waters. However, datasets for many individual facilities are incomplete, the PCS/ICIS historical data date back only to 1989, and historical data are available for only a limited number of facilities. Additionally, inconsistencies in facility reporting make it difficult to track or identify changes in nutrient discharges over time. Previous efforts made by the U.S. Geological Survey to “fill in” gaps in the PCS/ICIS data were based on statistical methods—missing data were filled in through the use of a statistical model based on the Standard Industrial Classification code, size, and flow class of the facility and on seasonal nutrient discharges of similar facilities. This approach was used to estimate point-source loads for a single

  16. Pulsating variable stars and large spectroscopic surveys

    Science.gov (United States)

    De Cat, Peter

    2017-09-01

    In the past decade, the research of pulsating variable stars has taken a giant leap forward thanks to the photometric measurements provided by space missions like Most, CoRoT, Kepler/K2, and Brite. These missions have provided quasi uninterrupted photometric time-series with an ultra-high quality and a total length that is not achievable from Earth. However, many of the success stories could not have been told without ground-based spectroscopic follow-up observations. Indeed, spectroscopy has some important assets as it can provide (more) accurate information about stellar parameters (like the effective temperature, surface gravity, metallicity, and abundances that are mandatory parameters for an in-depth asteroseismic study), the radial velocity (that is important for the detection of binaries and for the confirmation of cluster membership, if applicable), and the projected rotational velocity (that allows the study of the effects of rotation on pulsations). Fortunately, several large spectroscopic surveys are (becoming) available that can be used for these purposes. For some of these surveys, sub-projects have been initiated with the specific goal to complement space-based photometry. In this review, several spectroscopic surveys are introduced and compared with each other. We show that a large amount of spectroscopic data is (becoming) available for a large variety of objects.

  17. The Draco Nebula, a Molecular Cloud Associated with a High Velocity Cloud?

    Science.gov (United States)

    Mebold, U.; Kalberla, P. W. M.

    1984-01-01

    Extended and very faint bright nebulae are found in high galactic latitudes at the Palomar Observatory Sky Survey. Such a nebula, located in the constellation Draco and called Draco Nebula or Dracula, was found to be in detailed positional coincidence with a 21 cm emission line feature. Estimates of the minimum visual extinction from star counts ON and OFF Dracula and an estimated visual surface brightness indicate that Dracula fits the relation SBV = 24.2 - 2.5 log AV for dust clouds located above the galactic plane and reflecting the integrated starlight of the galactic disk. Hence Dracula is probably a reflection nebula. Indicators of molecular hydrogen in Dracula, molecules such as CO, were searched for by using a 2.5-m mm-telescope. Molecular hydrogen column densities were estimated. The dynamics of CO clumps was studied. Dracula has a close positional and possibly even astrophysical relationship to the high velocity cloud phenomenon.

  18. Draco Nebula, a molecular cloud associated with a high velocity cloud

    Energy Technology Data Exchange (ETDEWEB)

    Mebold, U.; Kalberla, P.W.M.

    1984-11-01

    Extended and very faint bright nebulae are found in high galactic latitudes at the Palomar Observatory Sky Survey. Such a nebula, located in the constellation Draco and called Draco Nebula or Dracula, was found to be in detailed positional coincidence with a 21 cm emission line feature. Estimates of the minimum visual extinction from star counts ON and OFF Dracula and an estimated visual surface brightness indicate that Dracula fits the relation SBV 24.2 - 2.5 log AV for dust clouds located above the galactic plane and reflecting the integrated starlight of the galactic disk. Hence Dracula is probably a reflection nebula. Indicators of molecular hydrogen in Dracula, molecules such as CO, were searched for by using a 2.5-m mm-telescope. Molecular hydrogen column densities were estimated. The dynamics of CO clumps was studied. Dracula has a close positional and possibly even astrophysical relationship to the high velocity cloud phenomenon.

  19. Fast and Efficient Approach in Surface Wave Analysis

    Science.gov (United States)

    Kanli, A. I.

    2010-12-01

    Fast and Efficient Approach in Surface Wave Analysis Ali Ismet KANLI Istanbul University, Engineering Faculty, Department of Geophysical Engineering, 34320, Avcilar Campus, Istanbul-Turkey, E-mail: kanli@istanbul.edu.tr Abstract: A two-step surface wave analysis method is proposed including both the MASW (Multi-channel Analysis of Surface Waves) and Micro-tremor based techniques. This is an integrated approach and the MASW survey data are gathered to obtain the shear wave velocity-depth information up to at least 30 meters by using a special type active seismic source called as SR-II or Kangaroo. In the second step, the microtremor data which are based on surface waves from seismic noise at each site are used to determine the shear-wave velocity-depth profiles. In the second step of the process, the multichannel analysis of surface waves data are given as constraints in the microtremor inversion process. This proposed algorithm allows us to calculate shear wave velocity-depth information with all geotechnical parameters from near surface to bedrock depths very fast and efficiently.

  20. Critical velocity experiments in space

    Science.gov (United States)

    Torbert, R. B.

    1988-01-01

    Published data from active space experiments designed to demonstrate the Alfven critical-velocity effect are compiled in graphs and compared with the predictions of numerical simulations. It is found that the discrepancies in the ionization yields obtained in shaped-charge releases of alkali metals are related to the macroscopic limits of time and energy in such releases. It is argued that the total ionization yield is an inadequate measure of the critical-velocity effect, and a new criterion based on eta, the efficiency of energy transfer from the recently ionized neutrals to a heated electron population, is proposed: the effect would be verified if eta values of 10 percent or greater were observed.

  1. 2MTF - VI. Measuring the velocity power spectrum

    Science.gov (United States)

    Howlett, Cullan; Staveley-Smith, Lister; Elahi, Pascal J.; Hong, Tao; Jarrett, Tom H.; Jones, D. Heath; Koribalski, Bärbel S.; Macri, Lucas M.; Masters, Karen L.; Springob, Christopher M.

    2017-11-01

    We present measurements of the velocity power spectrum and constraints on the growth rate of structure fσ8, at redshift zero, using the peculiar motions of 2062 galaxies in the completed 2MASS Tully-Fisher survey (2MTF). To accomplish this we introduce a model for fitting the velocity power spectrum including the effects of non-linear redshift space distortions (RSD), allowing us to recover unbiased fits down to scales k = 0.2 h Mpc-1 without the need to smooth or grid the data. Our fitting methods are validated using a set of simulated 2MTF surveys. Using these simulations we also identify that the Gaussian distributed estimator for peculiar velocities of Watkins & Feldman is suitable for measuring the velocity power spectrum, but sub-optimal for the 2MTF data compared to using magnitude fluctuations δm, and that, whilst our fits are robust to a change in fiducial cosmology, future peculiar velocity surveys with more constraining power may have to marginalize over this. We obtain scale-dependent constraints on the growth rate of structure in two bins, finding fσ 8 = [0.55^{+0.16}_{-0.13},0.40^{+0.16}_{-0.17}] in the ranges k = [0.007-0.055, 0.55-0.150] h Mpc-1. We also find consistent results using four bins. Assuming scale-independence we find a value fσ 8 = 0.51^{+0.09}_{-0.08}, a ˜16 per cent measurement of the growth rate. Performing a consistency check of general relativity (GR) and combining our results with cosmic microwave background data only we find γ = 0.45^{+0.10}_{-0.11}, a remarkable constraint considering the small number of galaxies. All of our results are completely independent of the effects of galaxy bias, and fully consistent with the predictions of GR (scale-independent fσ8 and γ ≈ 0.55).

  2. Movement velocity vs. strength training

    Directory of Open Access Journals (Sweden)

    Mário C. Marques

    2017-06-01

    practice in strength training, but increasing evidence (Sanborn et al., 2000; Folland et al., 2002; Izquierdo et al., 2006; Drinkwater et al., 2007 shows that training to repetition failure does not necessarily produce better strength gains and that may even be counterproductive by inducing excessive fatigue, mechanical and metabolic strain (Fry, 2004. In fact, fatigue associated with training to failure not only significantly reduces the force that a muscle can generate, but also the nervous system’s ability to voluntarily activate the muscles (Häkkinen, 1993. Consequently, this approach, besides being very tiring and having shown no advantage over other lower effort types of training, it is unrealistic because it is practically impossible to know exactly how many repetitions can be done with a given absolute load without any initial reference. In addition, if in the first set the subject has completed the maximum number of repetitions, it will be very difficult or even impossible to perform properly the same number of reps in the following sets. Movement velocity is another variable which could be of great interest for monitoring exercise intensity, but surprisingly it has been vaguely mentioned in most studies to date. The importance that monitoring movement velocity for strength training programming have already been noticed in 1991 (González-Badillo, 1991. More recently, González-Badillo and Sánchez-Medina (2010, 2011 studied this hypothesis and confirmed that movement velocity provides as a determinant of the level of effort during resistance training as well as an indicator of the degree of fatigue. Unfortunately, the lack of use of this variable is likely because until recently it was not possible to accurately measure velocity in isoinertial strength training exercises/movements.  Indeed, most research that has addressed movement velocity in strength training was basically conducted using isokinetic apparatus which, unfortunately, is not an ideal or common

  3. Notes on fk analysis of surface waves

    Directory of Open Access Journals (Sweden)

    L. V. Socco

    2000-06-01

    Full Text Available The dispersive nature of Rayleigh waves is the basis of many identification procedures to infer the site stiffness profile from surface measurements. This article presents some important aspects related to fk analysis of seismic gathers, which is one of the procedures commonly used to obtain the experimental dispersion curve, focusing on the great influence that the scale of the survey has in the global process. At a short distance from the source, the seismic signal contains information related to different modes of propagation in a composite form. As the wave travels away, the different modal group velocities produce a separation of such information. Hence only if the testing array is sufficiently long is it possible to assume mode separation and to invert the dispersion curve for modal velocities. Otherwise the effects of mode superposition need to be carefully accounted for. To clarify this concept, the results of some numerical simulations are reported, together with some experimental results.

  4. Probing the critical zone using passive- and active-source estimates of subsurface shear-wave velocities

    Science.gov (United States)

    Callahan, R. P.; Taylor, N. J.; Pasquet, S.; Dueker, K. G.; Riebe, C. S.; Holbrook, W. S.

    2016-12-01

    Geophysical imaging is rapidly becoming popular for quantifying subsurface critical zone (CZ) architecture. However, a diverse array of measurements and measurement techniques are available, raising the question of which are appropriate for specific study goals. Here we compare two techniques for measuring S-wave velocities (Vs) in the near surface. The first approach quantifies Vs in three dimensions using a passive source and an iterative residual least-squares tomographic inversion. The second approach uses a more traditional active-source seismic survey to quantify Vs in two dimensions via a Monte Carlo surface-wave dispersion inversion. Our analysis focuses on three 0.01 km2 study plots on weathered granitic bedrock in the Southern Sierra Critical Zone Observatory. Preliminary results indicate that depth-averaged velocities from the two methods agree over the scales of resolution of the techniques. While the passive- and active-source techniques both quantify Vs, each method has distinct advantages and disadvantages during data acquisition and analysis. The passive-source method has the advantage of generating a three dimensional distribution of subsurface Vs structure across a broad area. Because this method relies on the ambient seismic field as a source, which varies unpredictably across space and time, data quality and depth of investigation are outside the control of the user. Meanwhile, traditional active-source surveys can be designed around a desired depth of investigation. However, they only generate a two dimensional image of Vs structure. Whereas traditional active-source surveys can be inverted quickly on a personal computer in the field, passive source surveys require significantly more computations, and are best conducted in a high-performance computing environment. We use data from our study sites to compare these methods across different scales and to explore how these methods can be used to better understand subsurface CZ architecture.

  5. Engineering surveying

    CERN Document Server

    Schofield, W

    2007-01-01

    Engineering surveying involves determining the position of natural and man-made features on or beneath the Earth's surface and utilizing these features in the planning, design and construction of works. It is a critical part of any engineering project. Without an accurate understanding of the size, shape and nature of the site the project risks expensive and time-consuming errors or even catastrophic failure.Engineering Surveying 6th edition covers all the basic principles and practice of this complex subject and the authors bring expertise and clarity. Previous editions of this classic text have given readers a clear understanding of fundamentals such as vertical control, distance, angles and position right through to the most modern technologies, and this fully updated edition continues that tradition.This sixth edition includes:* An introduction to geodesy to facilitate greater understanding of satellite systems* A fully updated chapter on GPS, GLONASS and GALILEO for satellite positioning in surveying* Al...

  6. 2011 Tohoku tsunami video and TLS based measurements: hydrographs, currents, inundation flow velocities, and ship tracks

    Science.gov (United States)

    Fritz, H. M.; Phillips, D. A.; Okayasu, A.; Shimozono, T.; Liu, H.; Takeda, S.; Mohammed, F.; Skanavis, V.; Synolakis, C. E.; Takahashi, T.

    2012-12-01

    The March 11, 2011, magnitude Mw 9.0 earthquake off the coast of the Tohoku region caused catastrophic damage and loss of life in Japan. The mid-afternoon tsunami arrival combined with survivors equipped with cameras on top of vertical evacuation buildings provided spontaneous spatially and temporally resolved inundation recordings. This report focuses on the surveys at 9 tsunami eyewitness video recording locations in Myako, Kamaishi, Kesennuma and Yoriisohama along Japan's Sanriku coast and the subsequent video image calibration, processing, tsunami hydrograph and flow velocity analysis. Selected tsunami video recording sites were explored, eyewitnesses interviewed and some ground control points recorded during the initial tsunami reconnaissance in April, 2011. A follow-up survey in June, 2011 focused on terrestrial laser scanning (TLS) at locations with high quality eyewitness videos. We acquired precise topographic data using TLS at the video sites producing a 3-dimensional "point cloud" dataset. A camera mounted on the Riegl VZ-400 scanner yields photorealistic 3D images. Integrated GPS measurements allow accurate georeferencing. The original video recordings were recovered from eyewitnesses and the Japanese Coast Guard (JCG). The analysis of the tsunami videos follows an adapted four step procedure originally developed for the analysis of 2004 Indian Ocean tsunami videos at Banda Aceh, Indonesia (Fritz et al., 2006). The first step requires the calibration of the sector of view present in the eyewitness video recording based on ground control points measured in the LiDAR data. In a second step the video image motion induced by the panning of the video camera was determined from subsequent images by particle image velocimetry (PIV) applied to fixed objects. The third step involves the transformation of the raw tsunami video images from image coordinates to world coordinates with a direct linear transformation (DLT) procedure. Finally, the instantaneous tsunami

  7. Three dimensional reflection velocity analysis based on velocity model scan; Model scan ni yoru sanjigen hanshaha sokudo kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Minegishi, M.; Tsuru, T. [Japan National Oil Corp., Tokyo (Japan); Matsuoka, T. [Japan Petroleum Exploration Corp., Tokyo (Japan)

    1996-05-01

    Introduced herein is a reflection wave velocity analysis method using model scanning as a method for velocity estimation across a section, the estimation being useful in the construction of a velocity structure model in seismic exploration. In this method, a stripping type analysis is carried out, wherein optimum structure parameters are determined for reflection waves one after the other beginning with those from shallower parts. During this process, the velocity structures previously determined for the shallower parts are fixed and only the lowest of the layers undergoing analysis at the time is subjected to model scanning. To consider the bending of ray paths at each velocity boundaries involving shallower parts, the ray path tracing method is utilized for the calculation of the reflection travel time curve for the reflection surface being analyzed. Out of the reflection wave travel time curves calculated using various velocity structure models, one that suits best the actual reflection travel time is detected. The degree of matching between the calculated result and actual result is measured by use of data semblance in a time window provided centering about the calculated reflective wave travel time. The structure parameter is estimated on the basis of conditions for the maximum semblance. 1 ref., 4 figs.

  8. Carbon dioxide, temperature, salinity, and atmospheric pressure from surface underway survey in the North Pacific from January 1998 to January 2004 (NODC Accession 0045502)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea surface pCO2, sea surface temperature, sea surface salinity, and atmospheric pressure measurements collected in the North Pacific as part of the NOAA Office of...

  9. Constraining cosmology with the velocity function of low-mass galaxies

    Science.gov (United States)

    Schneider, Aurel; Trujillo-Gomez, Sebastian

    2018-01-01

    The number density of field galaxies per rotation velocity, referred to as the velocity function, is an intriguing statistical measure probing the smallest scales of structure formation. In this paper we point out that the velocity function is sensitive to small shifts in key cosmological parameters such as the amplitude of primordial perturbations (σ8) or the total matter density (Ωm). Using current data and applying conservative assumptions about baryonic effects, we show that the observed velocity function of the Local Volume favours cosmologies in tension with the measurements from Planck but in agreement with the latest findings from weak lensing surveys. While the current systematics regarding the relation between observed and true rotation velocities are potentially important, upcoming data from HI surveys as well as new insights from hydrodynamical simulations will dramatically improve the situation in the near future.

  10. Abandoned Mine Detection in Western Pennsylvania Using Surface Wave Data

    Science.gov (United States)

    Miller, B.

    2015-12-01

    Abandoned mines throughout the Appalachian region of the United States have been recognized as problematic. Resource extraction from these mines has long ceased and few, if any, documents pertaining to these operations exist. Over time support structures internal to the mines may collapse and lead to subsidence, potentially damaging surface structures. A non-invasive, surface deployed seismic method to detect undisclosed, abandoned near-surface mines would be beneficial as a first step to remediation. The use of seismic surface waves to analyze the upper several tens of meters of the subsurface has become an important technique for near-surface investigations and may provide a method for detection of near-surface, abandoned mine shafts. While there are many undocumented abandoned mines throughout the Appalachians one known example exists within Butler County, Pennsylvania. Although little is known about the overall operation there is limited documentation which provides information as to the location of the mine tunnels. Currently there is no recognized surface subsidence associated with the mine however documents indicate that the abandoned mining operations have an estimated depth ranging from twenty to fifty feet. To assist with acquisition a seismic land streamer was constructed. Use of a land streamer increases the speed, ease and efficiency required to perform a seismic survey. Additionally the land streamer allows for the acquisition of seismic surface waves which were analyzed using the Multichannel Analysis of Surface Waves (MASW) method. Data were acquired by conducting multiple, adjacent surveys perpendicular to the suspected location of abandoned mine tunnels. Throughout the survey area to a depth of approximately 15 meters, shear wave velocities range between approximately 200-1200 m/s. Based upon shear wave velocity changes within the profile anomalies have been identified corresponding to the contrast between the suspected mined, and unmined, areas.

  11. Streamwise decrease of the 'unsteady' virtual velocity of gravel tracers

    Science.gov (United States)

    Klösch, Mario; Gmeiner, Philipp; Habersack, Helmut

    2017-04-01

    travel velocities directly after seeding (representing the velocity of sediment at the bed surface subject to actual transport), or the longer term transport of sediment, helping to understand the velocity of sediment transfer in river networks as a basis for catchment-wide river restoration plans in the course of the project 'HyMoCARES', which is co-financed by the European Regional Development Fund within the Alpine Space programme.

  12. Cavity Enhanced Velocity Modulation Spectroscopy

    Science.gov (United States)

    Siller, Brian; Mills, Andrew; Porambo, Michael; McCall, Benjamin

    2010-11-01

    Over the past several decades, velocity modulation spectroscopy has been used to study dozens of molecular ions of astronomical importance. This technique has been so productive because it provides the advantage of ion-neutral discrimination, which is critically important when interfering neutral molecules are many orders of magnitude more abundant, and when combined with heterodyne techniques, its sensitivity can approach the shot noise limit. Traditionally, velocity modulation experiments have utilized unidirectional multipass White cells to achieve up to about 8 passes through a positive column discharge cell. But by positioning the cell within an optical cavity, it is possible to obtain an effective path length orders of magnitude longer than was previously possible. We have demonstrated this novel technique using a Ti:Sapp laser in the near-IR to observe rovibronic transitions of N2+. By demodulating at twice the modulation frequency, 2nd derivative-like lineshapes are observed for ions that are velocity-modulated, while Gaussian lineshapes are observed for excited neutral that are concentration-modulated. The signals for N2+ and N2+* have been observed to be 78° out of phase with one another, so ion-neutral discrimination is retained. And due to the laser power enhancement and geometry of the optical cavity, Doppler-free saturation spectroscopy is now possible. Observed Lamb dips have widths of 50 MHz, and when combined with calibration by an optical frequency comb, this allows for determination of line centers to within 1 MHz. In our original demonstration of this technique, our sensitivity was limited by noise in the laser-cavity lock. Since then, we have integrated Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectroscopy (NICE-OHMS) by adding sidebands to the laser at an exact multiple of the cavity free spectral range, and demodulating at the sideband frequency before sending the signal to a lock-in amplifier for demodulating at twice the

  13. Clear and Measurable Signature of Modified Gravity in the Galaxy Velocity Field

    Science.gov (United States)

    Hellwing, Wojciech A.; Barreira, Alexandre; Frenk, Carlos S.; Li, Baojiu; Cole, Shaun

    2014-06-01

    The velocity field of dark matter and galaxies reflects the continued action of gravity throughout cosmic history. We show that the low-order moments of the pairwise velocity distribution v12 are a powerful diagnostic of the laws of gravity on cosmological scales. In particular, the projected line-of-sight galaxy pairwise velocity dispersion σ12(r) is very sensitive to the presence of modified gravity. Using a set of high-resolution N-body simulations, we compute the pairwise velocity distribution and its projected line-of-sight dispersion for a class of modified gravity theories: the chameleon f(R) gravity and Galileon gravity (cubic and quartic). The velocities of dark matter halos with a wide range of masses would exhibit deviations from general relativity at the (5-10)σ level. We examine strategies for detecting these deviations in galaxy redshift and peculiar velocity surveys. If detected, this signature would be a "smoking gun" for modified gravity.

  14. Survey of the Occurrence and Human Infective Potential of Giardia duodenalis and Cryptosporidium spp. in Wastewater and Different Surface Water Sources of Western Romania.

    Science.gov (United States)

    Imre, Kálmán; Morar, Adriana; Ilie, Marius S; Plutzer, Judit; Imre, Mirela; Emil, Tîrziu; Herbei, Mihai V; Dărăbuș, Gheorghe

    2017-10-01

    From the group of parasitic protozoa, Giardia and Cryptosporidium are the most common pathogens spread in surface water sources, representing a continuous threat to public health and water authorities. The aim of this survey was to assess the occurrence and human infective potential of these pathogens in treated wastewaters and different surface water sources. A total of 76 western Romanian water bodies in four counties (Arad, Bihor, Caraș-Severin and Timiș) were investigated, including the effluents of wastewater treatment plants (n = 11) and brooks (n = 19), irrigation channels (n = 8), lakes (n = 16), and ponds (n = 22). Water samples were collected through polyester microfiber filtration. Giardia cysts and Cryptosporidium oocysts were isolated using immunomagnetic separation, according to the US EPA 1623 method, followed by their identification and counting by immunofluorescence (IF) microscopy. All samples were screened through PCR-based techniques targeting the gdh gene for Giardia spp. and the 18S rRNA gene for Cryptosporidium spp., followed by sequencing of the positive results. Cryptosporidium-positive samples were subtyped based on sequence analysis of the GP60 gene. Giardia spp. was found in all tested water types with a cumulative detection rate of 90.1% in wastewaters, 26.3% in brooks, 37.5% in irrigation channels, 31.2% in lakes, and 36.4% in ponds. Except for ponds, all monitored water bodies harbored the Giardia duodenalis AII subassemblage with human infective potential. In addition, the ruminant origin assemblage E was widely distributed, and the domestic/wild canid-specific assemblage D was also recorded in a pond. Three (27.3%) wastewater samples were Cryptosporidium positive, and the identified species was the zoonotic Cryptosporidium parvum, with IIaA15G2R1 (n = 2) and IIdA18G1 subtypes. The results highlight that this threat to the public health must be brought to the attention of epidemiologists, health officials

  15. Carbon film deposition from high velocity rarefied flow

    Energy Technology Data Exchange (ETDEWEB)

    Rebrov, A.K., E-mail: rebrov@itp.nsc.ru; Emelyanov, A.A.; Yudin, I.B.

    2015-01-30

    The presented study is based on the idea of the activation of a gas-precursor high velocity flow by hot wire. The wire forms the channel for flow before expansion to substrate. The construction allows change of the specific flow rate, velocity, composition and temperature of a gas mixture by studying the film synthesis in conditions from free molecular to continuum flow at velocities from hundreds to thousands of m/s. At a high pressure, the film has typical and unusual hexagonal incorporations for diamond tetragonal particles. Raman spectrum with the pronounced diamond peak is typical for diamond-like film. X-ray diffraction points in the presence of lonsdaleite. Conditions of deposition were simulated by Monte Carlo method. Collisions with hot surfaces and chemical transformations were taken into consideration as well.

  16. Starspot-induced radial velocity jitter during a stellar cycle

    DEFF Research Database (Denmark)

    Korhonen, Heidi Helena; Andersen, Jan Marie; Järvinen, Silva

    2012-01-01

    on the Sun and other cool stars changes cyclically during an activity cycle, which has length varying from about a year to longer than the solar 11 years. In this work we investigate the influence of varying amount of starspots on the sparsely sampled radial velocity observations - which are the norm......Late-type stars exhibit cool regions on their surface, the stellar equivalent of sunspots. These dark starspots can also mimic the radial velocity variations caused by orbiting planets, making it at times difficult to distinguish between planets and activity signatures. The amount of spots...... in the radial velocity studies searching for exoplanets on wide orbits. We study two simulated cases: one with a random spot configuration, and one where the spot occurrence is concentrated. In addition we use Doppler images of young solar analogue V889 Her as a high activity case....

  17. Detonation Velocity Measurement with Chirped Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Peng Wei

    2017-11-01

    Full Text Available Detonation velocity is an important parameter for explosive, and it is crucial for many fields such as dynamic chemistry burn models, detonation propagation prediction, explosive performance estimation, and so on. Dual-channel detonation velocity measurement method and system are described. The CFBG sensors are pasted both on the surface and in the center of the explosive cylinder. The length of CFBG sensors is measured via the hot-tip probe method. The light intensity reflected from the CFBG sensors attached to the explosive is transformed to voltage, and the voltage–time is then measured with the oscilloscope. According to the five experiments results, the relative standard uncertainty of detonation velocity is below 1%.

  18. 39 GHz Interferometer System for Measuring Detonation Velocity

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Patrick W. [National Security Technologies, LLC. (NSTec), Livermore, CA (United States); Tran, Vu [National Security Technologies, LLC. (NSTec), Livermore, CA (United States); Waltman, Thomas B. [National Security Technologies, LLC. (NSTec), Livermore, CA (United States); Tringe, Joe [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); May, Chadd [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Cradick, Jerry [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hodgin, Ralph [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kane, Ron [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-13

    A new 39 GHz RF interferometer system is presented for use in velocity measurements of high explosives (HE) detonations. The frequency was chosen to compliment the currently available suite, and provide more spatial information. An RF signal is generated and coupled to a waveguide adapter serving as an antenna. The HE is initially transparent to the RF. When the HE detonates, the detonation front becomes reflective to the RF. This reflection is picked up by the waveguide adapter and mixed with an unperturbed RF signal to give a low frequency signal which can be digitized with an oscilloscope. By comparing the signal with a reference signal, velocity information can be obtained using Fourier Transforms and wavelet models. Bench test results using a “slapper” are shown. The 39 GHz microwave interferometer is used in Deflagration to Detonation shots. The signal is reflected off a moving surface, and the Doppler shift of the reflected signal is used to calculate the velocity.

  19. Retrieval of sea surface velocities using sequential Ocean Colour ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The authors express their sincere gratitude to Dr. A K S Gopalan, Director SAC and. Dr. R R Navalgund, presently, Director, NRSA,. Hyderabad and earlier Deputy Director, RESA,. SAC for their guidance and valuable suggestions during the course of this study. They are also thankful to Dr. N Sengupta, the then Deputy.

  20. Phenomena Simulation for Heavy Doping and Surface Recombination Velocity

    Science.gov (United States)

    Lindholm, F. A.

    1985-01-01

    The theoretical models now available that characterize heavily doped (highly conducting) regions in silicon are survyed. Analytical and numerical approaches that determine the influence of such regions on the conversion efficiency of solar cells are examined. Although dilutely doped silicon is well characterized except for some disagreement about optical absorption coefficients, what exists now for heavily doped silicon and its interplay with adjoining regions is an incomplete theory in which not all contributers to transport, recombination, generation, and trapping are defined. Further, the parameters relating to these mechanisms and their values as determined by experiment are subject to various interpretations. The characterization of heavily doped silicon is treated not as a theory but rather as an imperfectly articulated and incompletely formalized body of experience. This view is intended to help point the way toward the attainment of a more complete of heavily doped silicon and thereby toward more informed designs of solar cells. Because computer programs constitute tools both for design and for estimating performance limits, the review includes some remarks pertinent to existing and developing programs.

  1. A Fabry-Perot interferometer system for high-speed velocity measurement

    NARCIS (Netherlands)

    Cheng, L.K.; Bruinsma, A.J.A.; Prinse, W.C.; Smorenburg, C.

    1997-01-01

    The Fabry-Perot Velocity Interferometer System (F-PVIS) is designed and built for measuring the Doppler shift of light by recording positional changes in the interferometric pattern behind the Fabry-Perot interferometer. The velocity of a surface can be deduced from the Doppler shift which is caused

  2. Exploiting LSPIV to assess debris-flow velocities in the field

    Directory of Open Access Journals (Sweden)

    J. I. Theule

    2018-01-01

    Full Text Available The assessment of flow velocity has a central role in quantitative analysis of debris flows, both for the characterization of the phenomenology of these processes and for the assessment of related hazards. Large-scale particle image velocimetry (LSPIV can contribute to the assessment of surface velocity of debris flows, provided that the specific features of these processes (e.g. fast stage variations and particles up to boulder size on the flow surface are taken into account. Three debris-flow events, each of them consisting of several surges featuring different sediment concentrations, flow stages, and velocities, have been analysed at the inlet of a sediment trap in a stream in the eastern Italian Alps (Gadria Creek. Free software has been employed for preliminary treatment (orthorectification and format conversion of video-recorded images as well as for LSPIV application. Results show that LSPIV velocities are consistent with manual measurements of the orthorectified imagery and with front velocity measured from the hydrographs in a channel recorded approximately 70 m upstream of the sediment trap. Horizontal turbulence, computed as the standard deviation of the flow directions at a given cross section for a given surge, proved to be correlated with surface velocity and with visually estimated sediment concentration. The study demonstrates the effectiveness of LSPIV in the assessment of surface velocity of debris flows and permit the most crucial aspects to be identified in order to improve the accuracy of debris-flow velocity measurements.

  3. Exploiting LSPIV to assess debris-flow velocities in the field

    Science.gov (United States)

    Theule, Joshua I.; Crema, Stefano; Marchi, Lorenzo; Cavalli, Marco; Comiti, Francesco

    2018-01-01

    The assessment of flow velocity has a central role in quantitative analysis of debris flows, both for the characterization of the phenomenology of these processes and for the assessment of related hazards. Large-scale particle image velocimetry (LSPIV) can contribute to the assessment of surface velocity of debris flows, provided that the specific features of these processes (e.g. fast stage variations and particles up to boulder size on the flow surface) are taken into account. Three debris-flow events, each of them consisting of several surges featuring different sediment concentrations, flow stages, and velocities, have been analysed at the inlet of a sediment trap in a stream in the eastern Italian Alps (Gadria Creek). Free software has been employed for preliminary treatment (orthorectification and format conversion) of video-recorded images as well as for LSPIV application. Results show that LSPIV velocities are consistent with manual measurements of the orthorectified imagery and with front velocity measured from the hydrographs in a channel recorded approximately 70 m upstream of the sediment trap. Horizontal turbulence, computed as the standard deviation of the flow directions at a given cross section for a given surge, proved to be correlated with surface velocity and with visually estimated sediment concentration. The study demonstrates the effectiveness of LSPIV in the assessment of surface velocity of debris flows and permit the most crucial aspects to be identified in order to improve the accuracy of debris-flow velocity measurements.

  4. Recording of particles velocity spectrum at the shock impact on different viscosity interface of liquids

    Directory of Open Access Journals (Sweden)

    Fedorov A.V.

    2015-01-01

    Full Text Available The results of experiments concerning the study of cavitational mechanism of liquid failure in a wide range of shock loading are presented in this paper. Free surface velocity of liquids and velocity spectrum of particles and jets were recorded using PDV method [1], their size was also determined. The value of spall strength of distilled water was defined.

  5. Velocity field calculation for non-orthogonal numerical grids

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-03-01

    Computational grids containing cell faces that do not align with an orthogonal (e.g. Cartesian, cylindrical) coordinate system are routinely encountered in porous-medium numerical simulations. Such grids are referred to in this study as non-orthogonal grids because some cell faces are not orthogonal to a coordinate system plane (e.g. xy, yz or xz plane in Cartesian coordinates). Non-orthogonal grids are routinely encountered at the Savannah River Site in porous-medium flow simulations for Performance Assessments and groundwater flow modeling. Examples include grid lines that conform to the sloping roof of a waste tank or disposal unit in a 2D Performance Assessment simulation, and grid surfaces that conform to undulating stratigraphic surfaces in a 3D groundwater flow model. Particle tracking is routinely performed after a porous-medium numerical flow simulation to better understand the dynamics of the flow field and/or as an approximate indication of the trajectory and timing of advective solute transport. Particle tracks are computed by integrating the velocity field from cell to cell starting from designated seed (starting) positions. An accurate velocity field is required to attain accurate particle tracks. However, many numerical simulation codes report only the volumetric flowrate (e.g. PORFLOW) and/or flux (flowrate divided by area) crossing cell faces. For an orthogonal grid, the normal flux at a cell face is a component of the Darcy velocity vector in the coordinate system, and the pore velocity for particle tracking is attained by dividing by water content. For a non-orthogonal grid, the flux normal to a cell face that lies outside a coordinate plane is not a true component of velocity with respect to the coordinate system. Nonetheless, normal fluxes are often taken as Darcy velocity components, either naively or with accepted approximation. To enable accurate particle tracking or otherwise present an accurate depiction of the velocity field for a non

  6. Balance velocities of the Greenland ice sheet

    DEFF Research Database (Denmark)

    Joughin, I.; Fahnestock, M.; Ekholm, Simon

    1997-01-01

    We present a map of balance velocities for the Greenland ice sheet. The resolution of the underlying DEM, which was derived primarily from radar altimetery data, yields far greater detail than earlier balance velocity estimates for Greenland. The velocity contours reveal in striking detail......, the balance map is useful for ice-sheet modelling, mass balance studies, and field planning....

  7. VELOCITY ANISOTROPY IN THE NIGER VDELTTXFSEDIMENTS ...

    African Journals Online (AJOL)

    Keywords: Intrinsic velocity anisotropy, Niger Delta, Thomsen's parameters, vertical i transverse isotropy (VT!) Introduction. In seismology, a layer is anisotropic if seismic waves propagate through it at different velocities in different directions. Sedimentary rocks possess some degree of intrinsic velocity anisotropy (Jones and.

  8. Sedimentary thickness and velocity in the northeast boundary of the Parana Basin with Andean earthquakes and local events; Espessura e velocidade das camadas sedimentares na borda nordeste da Bacia do Parana utilizando telessismos da regiao andina e sismos locais

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Josimar A.; Souza, Luiz M. [Universidade de Sao Paulo (USP), SP (Brazil). Dept. de Geofisica; Assumpcao, Marcelo S. [Universidade de Sao Paulo (USP), SP (Brazil)

    2008-07-01

    Deep Andean earthquakes are a suitable source of high-frequency P-waves (with good signal to noise ratio up to {approx} 10 Hz) that can be used to obtain high-resolution receiver functions at stations in intra-cratonic basins in Brazil. Receiver functions (Gaussian width 20) at five stations in the Bebedouro seismic area (NE Parana Basin) were calculated using the time domain deconvolution of Ligorria and Ammon (1999). Inter-station Rayleigh wave phase velocities were measured using local earthquakes. Joint inversion of receiver functions and Rayleigh phase velocities provided reasonably well constrained S-wave velocity profiles. Shallow seismic refraction surveys were used to fix the velocities of the surface layers during the inversion. The area is characterized by a thin surface layer of sandstones ({approx}60 m), followed by a {approx}500 m thick basalt layer. Beneath the basalts, low-velocity layers define another sedimentary sequence. These features are consistent with the expected values based on well data at regional distances and confirm the usefulness of high-frequency receiver functions to study sedimentary basins. (author)

  9. Featured Image: The Cosmic Velocity Web

    Science.gov (United States)

    Kohler, Susanna

    2017-09-01

    You may have heard of the cosmic web, a network of filaments, clusters and voids that describes the three-dimensional distribution of matter in our universe. But have you ever considered the idea of a cosmic velocity web? In a new study led by Daniel Pomarde (IRFU CEA-Saclay, France), a team of scientists has built a detailed 3D view of the flows in our universe, showing in particular motions along filaments and in collapsing knots. In the image above (click for the full view), surfaces of knots (red) are embedded within surfaces of filaments (grey). The rainbow lines show the flow motion, revealing acceleration (redder tones) toward knots and retardation (bluer tones) beyond them. You can learn more about Pomarde and collaborators work and see their unusual and intriguing visualizationsin the video they produced, below. Check out the original paper for more information.CitationDaniel Pomarde et al 2017 ApJ 845 55. doi:10.3847/1538-4357/aa7f78

  10. Effects of soil moisture variations on deposition velocities above vegetation.

    Energy Technology Data Exchange (ETDEWEB)

    Wesely, M. L.; Song, J.; McMillen, R. T.; Meyers, T. P.; Environmental Research; Northern Illinois Univ.; National Oceanic and Atmospheric Administration

    2001-01-01

    The parameterized subgrid-scale surface flux (PASS) model provides a simplified means of using remote sensing data from satellites and limited surface meteorological information to estimate the influence of soil moisture on bulk canopy stomatal resistances to the uptake of gases over extended areas. PASS-generated estimates of bulk canopy stomatal resistance were used in a dry deposition module to compute gas deposition velocities with a horizontal resolution of 200 m for approximately 5000 km{sup 2} of agricultural crops and rangeland. Results were compared with measurements of O{sub 3} flux and concentrations made during April and May 1997 at two surface stations and from an aircraft. The trend in simulated O{sub 3} deposition velocity during soil moisture drydown over a period of a few days matched the trend observed at the two surface stations. For areas under the aircraft flight paths, the variability in simulated O{sub 3} deposition velocity was substantially smaller than the observed variability, while the averages over tens of kilometers were usually in agreement within 0.1 cm s{sup -1}. Model results indicated that soil moisture can have a major role in deposition of O{sub 3} and other substances strongly affected by canopy stomatal resistance.

  11. Velocity of climate change algorithms for guiding conservation and management.

    Science.gov (United States)

    Hamann, Andreas; Roberts, David R; Barber, Quinn E; Carroll, Carlos; Nielsen, Scott E

    2015-02-01

    The velocity of climate change is an elegant analytical concept that can be used to evaluate the exposure of organisms to climate change. In essence, one divides the rate of climate change by the rate of spatial climate variability to obtain a speed at which species must migrate over the surface of the earth to maintain constant climate conditions. However, to apply the algorithm for conservation and management purposes, additional information is needed to improve realism at local scales. For example, destination information is needed to ensure that vectors describing speed and direction of required migration do not point toward a climatic cul-de-sac by pointing beyond mountain tops. Here, we present an analytical approach that conforms to standard velocity algorithms if climate equivalents are nearby. Otherwise, the algorithm extends the search for climate refugia, which can be expanded to search for multivariate climate matches. With source and destination information available, forward and backward velocities can be calculated allowing useful inferences about conservation of species (present-to-future velocities) and management of species populations (future-to-present velocities). © 2014 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

  12. 2011 Japan tsunami survivor video based hydrograph and flow velocity measurements using LiDAR

    Science.gov (United States)

    Fritz, H. M.; Phillips, D. A.; Okayasu, A.; Shimozono, T.; Liu, H.; Mohammed, F.; Skanavis, V.; Synolakis, C. E.; Takahashi, T.

    2012-04-01

    On March 11, 2011, a magnitude Mw 9.0 earthquake occurred off the coast of Japan's Tohoku region causing catastrophic damage and loss of life. Numerous tsunami reconnaissance trips were conducted in Japan (Tohoku Earthquake and Tsunami Joint Survey Group). This report focuses on the surveys at 9 tsunami eyewitness video recording locations in Yoriisohama, Kesennuma, Kamaishi and Miyako along Japan's Sanriku coast and the subsequent video image calibration, processing, tsunami hydrograph and flow velocity analysis. Selected tsunami video recording sites were visited, eyewitnesses interviewed and some ground control points recorded during the initial tsunami reconnaissance from April 9 to 25. A follow-up survey from June 9 to 15, 2011 focused on terrestrial laser scanning (TLS) at locations with previously identified high quality eyewitness videos. We acquired precise topographic data using TLS at nine video sites with multiple scans acquired from different instrument positions at each site. These ground-based LiDAR measurements produce a 3-dimensional "point cloud" dataset. Digital photography from a scanner-mounted camera yields photorealistic 3D images. Integrated GPS measurements allow accurate georeferencing of the TLS data in an absolute reference frame such as WGS84. We deployed a Riegl VZ-400 scanner (1550 nm wavelength laser, 42,000 measurements/second, requires the calibration of the sector of view present in the eyewitness video recording based on visually identifiable ground control points measured in the LiDAR point cloud data. In a second step the video image motion induced by the panning of the video camera was determined from subsequent raw color images by means of planar particle image velocimetry (PIV) applied to fixed objects in the field of view. The third step involves the transformation of the raw tsunami video images from image coordinates to world coordinates. The mapping from video frame to real world coordinates follows the direct linear

  13. 2011 Japan tsunami current and flow velocity measurements from survivor videos using LiDAR

    Science.gov (United States)

    Fritz, H. M.; Phillips, D. A.; Okayasu, A.; Shimozono, T.; Liu, H.; Mohammed, F.; Skanavis, V.; Synolakis, C.; Takahashi, T.

    2011-12-01

    On March 11, 2011, a magnitude Mw 9.0 earthquake occurred off the coast of Japan's Tohoku region causing catastrophic damage and loss of life. Numerous tsunami reconnaissance trips were conducted in Japan (Tohoku Earthquake and Tsunami Joint Survey Group). This report focuses on the surveys at 9 tsunami eyewitness video recording locations in Yoriisohama, Kesennuma, Kamaishi and Miyako along Japan's Sanriku coast and the subsequent video image calibration, processing and tsunami flow velocity analysis. Selected tsunami video recording sites were visited, eyewitnesses interviewed and some ground control points recorded during the initial tsunami reconnaissance from April 9 to 25. A follow-up survey from June 9 to 15, 2011 focused on terrestrial laser scanning (TLS) at locations with previously identified high quality eyewitness videos. We acquired precise topographic data using TLS at nine video sites with multiple scans acquired from different instrument positions at each site. These ground-based LiDAR measurements produce a 3-dimensional "point cloud" dataset. Digital photography from a scanner-mounted camera yields photorealistic 3D images. Integrated GPS measurements allow accurate georeferencing of the TLS data in an absolute reference frame such as WGS84. We deployed a Riegl VZ-400 scanner (1550 nm wavelength laser, 42,000 measurements/second, requires the calibration of the sector of view present in the eyewitness video recording based on visually identifiable ground control points measured in the LiDAR point cloud data. In a second step the video image motion induced by the panning of the video camera was determined from subsequent raw color images by means of planar particle image velocimetry (PIV) applied to fixed objects in the field of view. The third step involves the transformation of the raw tsunami video images from image coordinates to world coordinates. The mapping from video frame to real world coordinates follows the direct linear transformation

  14. Vector blood velocity estimation in medical ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Gran, Fredrik; Udesen, Jesper

    2006-01-01

    Two methods for making vector velocity estimation in medical ultrasound are presented. All of the techniques can find both the axial and transverse velocity in the image and can be used for displaying both the correct velocity magnitude and direction. The first method uses a transverse oscillation...... in the ultrasound field to find the transverse velocity. In-vivo examples from the carotid artery are shown, where complex turbulent flow is found in certain parts of the cardiac cycle. The second approach uses directional beam forming along the flow direction to estimate the velocity magnitude. Using a correlation...

  15. Relações entre tamanho de sedimentos erodidos, velocidade da enxurrada, rugosidade superficial criada pelo preparo e tamanho de agregados em solo submetido a diferentes manejos Relationships between size of eroded sediments, runoff velocity, surface roughness created by tillage, and size of aggregates in a soil submmited to different managements

    Directory of Open Access Journals (Sweden)

    Leandro Bochi da Silva Volk

    2009-10-01

    aggregates. Considering that, this work was accomplished with the purpose of establishing quantitative relationships between the D50 index of the size distribution of the soil-eroded sediments, the runoff velocity, the SR index of the tillage-induced soil surface roughness, and the mean weight diameter (MWD of the soil aggregates, in a soil submitted to different forms of management. The study was developed in the field, at the Agricultural Experimentation Station of the Federal University of Rio Grande do Sul (EEA/UFRGS, in Eldorado do Sul (RS, Brazil, by applying simulated rainfall on an Ultisol with a sandy clay loam texture in the surface layer and 0.115 m m-1 average slope steepness. This soil had been put into agricultural use by different manners (continuous and discontinued cultivation, with different crop sequences (winter and summer, grass and legume crop species, planted in rows, using no-tillage, for a 7.5 year period (starting at the original condition of native pasture. Seven erosion tests were performed in the study, each one of them at 63.5 mm h-1 rainfall intensity and 1.5 h duration, using the rotating-boom rainfall simulator and 3.5 x 11.0 m experimental plots. The referred erosion tests were performed in the following soil surface physical conditions: (a non-mobilized soil, with complete and no cover by crop residues, and (b soil successively mobilized by the passage of a light disc-harrow (five times, one at a time, with no cover. It was observed that the crop sequences provided values of the MWD index significantly different each other, which reflected in significantly different values of the SR index and, as consequence, of the runoff velocity and the D50 index, with the sequences with none or less time of discontinued cultivation (in the last period of the research having produced the best results. In the non-mobilized, completely mulch-covered soil, with a firm and smooth surface, the mulch of crop residues was the dominant factor either in reducing

  16. Radial Velocity Variability of Field Brown Dwarfs

    Science.gov (United States)

    Prato, L.; Mace, G. N.; Rice, E. L.; McLean, I. S.; Kirkpatrick, J. Davy; Burgasser, A. J.; Kim, Sungsoo S.

    2015-07-01

    We present paper six of the NIRSPEC Brown Dwarf Spectroscopic Survey, an analysis of multi-epoch, high-resolution (R ˜ 20,000) spectra of 25 field dwarf systems (3 late-type M dwarfs, 16 L dwarfs, and 6 T dwarfs) taken with the NIRSPEC infrared spectrograph at the W. M. Keck Observatory. With a radial velocity (RV) precision of ˜2 km s-1, we are sensitive to brown dwarf companions in orbits with periods of a few years or less given a mass ratio of 0.5 or greater. We do not detect any spectroscopic binary brown dwarfs in the sample. Given our target properties, and the frequency and cadence of observations, we use a Monte Carlo simulation to determine the detection probability of our sample. Even with a null detection result, our 1σ upper limit for very low mass binary frequency is 18%. Our targets included seven known, wide brown dwarf binary systems. No significant RV variability was measured in our multi-epoch observations of these systems, even for those pairs for which our data spanned a significant fraction of the orbital period. Specialized techniques are required to reach the high precisions sensitive to motion in orbits of very low-mass systems. For eight objects, including six T dwarfs, we present the first published high-resolution spectra, many with high signal to noise, that will provide valuable comparison data for models of brown dwarf atmospheres.

  17. The Westerbork HI survey of spiral and irregular galaxies - II. R-band surface photometry of late-type dwarf galaxies

    NARCIS (Netherlands)

    Swaters, RA; Balcells, M

    R-band surface photometry is presented for 171 late-type dwarf and irregular galaxies. For a subsample of 46 galaxies B-band photometry is presented as well. We present surface brightness profiles as well as isophotal and photometric parameters including magnitudes, diameters and central surface

  18. Asymmetric metallicity patterns in the stellar velocity space with RAVE

    Science.gov (United States)

    Antoja, T.; Kordopatis, G.; Helmi, A.; Monari, G.; Famaey, B.; Wyse, R. F. G.; Grebel, E. K.; Steinmetz, M.; Bland-Hawthorn, J.; Gibson, B. K.; Bienaymé, O.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G.; Siebert, A.; Siviero, A.; Zwitter, T.

    2017-05-01

    Context. The chemical abundances of stars encode information on their place and time of origin. Stars formed together in e.g. a cluster, should present chemical homogeneity. Also disk stars influenced by the effects of the bar and the spiral arms might have distinct chemical signatures depending on the type of orbit that they follow, e.g. from the inner versus outer regions of the Milky Way. Aims: We explore the correlations between velocity and metallicity and the possible distinct chemical signatures of the velocity over-densities of the local Galactic neighbourhood. Methods: We use the large spectroscopic survey RAVE and the Geneva Copenhagen Survey. We compare the metallicity distribution of regions in the velocity plane (vR,vφ) with that of their symmetric counterparts (-vR,vφ). We expect similar metallicity distributions if there are no tracers of a sub-population (e.g. a dispersed cluster, accreted stars), if the disk of the Galaxy is axisymmetric, and if the orbital effects of the bar and the spiral arms are weak. Results: We find that the metallicity-velocity space of the solar neighbourhood is highly patterned. A large fraction of the velocity plane shows differences in the metallicity distribution when comparing symmetric vR regions. The typical differences in the median metallicity are of 0.05 dex with statistical significant of at least 95% confidence, and with values up to 0.6 dex. For stars with low azimuthal velocity vφ, the ones moving outwards. These include stars in the Hercules and Hyades moving groups and other velocity branch-like structures. For higher vφ, the stars moving inwards have higher metallicity than those moving outwards. We have also discovered a positive gradient in vφ with respect to metallicity at high metallicities, apart from the two known positive and negative gradients for the thick and thin disks. Conclusions: The most likely interpretation of the metallicity asymmetry is that it is mainly due to the orbital effects of

  19. Gouge initiation in high-velocity rocket sled testing

    Energy Technology Data Exchange (ETDEWEB)

    Tachau, R.D.M.; Trucano, T.G. [Sandia National Labs., Albuquerque, NM (United States); Yew, C.H. [Texas Univ., Austin, TX (United States)

    1994-07-01

    A model is presented which describes the formation of surface damage ``gouging`` on the rails that guide rocket sleds. An unbalanced sled can randomly cause a very shallow-angle, oblique impact between the sled shoe and the rail. This damage phenomenon has also been observed in high-velocity guns where the projectile is analogous to the moving sled shoe and the gun barrel is analogous to the stationary rail. At sufficiently high velocity, the oblique impact will produce a thin hot layer of soft material on the contact surfaces. Under the action of a normal moving load, the soft layer lends itself to an anti-symmetric deformation and the formation of a ``hump`` in front of the moving load. A gouge is formed when this hump is overrun by the sled shoe. The phenomenon is simulated numerically using the CTH strong shock physics code, and the results are in good agreement with experimental observation.

  20. Experimental Evaluation of Brittle Crack Propagation Velocity - an Improved Technique

    DEFF Research Database (Denmark)

    Debel, Christian

    1979-01-01

    A short review of experimental methods currently used in evaluating the velocity of fast crack extension is given. The technique of applying a surface deposited grid gauge has been innovated. This new technique involves a grid produced by a photo-chemical method and an electronic registration cir...... circuit based on integrated transistor-transistor logic. This new method has been applied to experimental studies of brittle crack extension in steel at temperatures between −115 and +22°C.......A short review of experimental methods currently used in evaluating the velocity of fast crack extension is given. The technique of applying a surface deposited grid gauge has been innovated. This new technique involves a grid produced by a photo-chemical method and an electronic registration...