WorldWideScience

Sample records for random mass-motion velocities

  1. Velocity and Dispersion for a Two-Dimensional Random Walk

    International Nuclear Information System (INIS)

    Li Jinghui

    2009-01-01

    In the paper, we consider the transport of a two-dimensional random walk. The velocity and the dispersion of this two-dimensional random walk are derived. It mainly show that: (i) by controlling the values of the transition rates, the direction of the random walk can be reversed; (ii) for some suitably selected transition rates, our two-dimensional random walk can be efficient in comparison with the one-dimensional random walk. Our work is motivated in part by the challenge to explain the unidirectional transport of motor proteins. When the motor proteins move at the turn points of their tracks (i.e., the cytoskeleton filaments and the DNA molecular tubes), some of our results in this paper can be used to deal with the problem. (general)

  2. Internal Mass Motion for Spacecraft Dynamics and Control

    National Research Council Canada - National Science Library

    Hall, Christopher D

    2008-01-01

    We present a detailed description of the application of a noncanonical Hamiltonian formulation to the modeling, analysis, and simulation of the dynamics of gyrostat spacecraft with internal mass motion...

  3. Mass motions in a quiescent filament

    International Nuclear Information System (INIS)

    Malherbe, J.M.; Mein, P.; Schmieder, B.

    1982-01-01

    Observations are presented of the sudden disappearance of a filament (N2O, E35) above an active region with the Multichannel Substractive Double Pass Spectrograph operating on the Meudon Solar Tower, France, from 10:45 UT to 13:30 UT on June 22, 1981. Measurements of the velocity fields and intensity fluctuations were obtained. It was found that the sudden disappearance did not take place simultaneously in all parts of the filament: thin threads with upward radial velocities reaching about 50 km/s were successively observed inside the prominence from the south to north regions. It is suggested that these motions corresponded to the rise of material along magnetic loops closely related to the prominence structure. An investigation of the dynamics inside such a magnetic loop shows a strongly accelerated high speed flow and a deformation of the flux tube, probably due to the centrifugal forces exerted by the flow on the magnetic lines. In addition, it is shown that the present theoretical models cannot account for the prominence structure as a cold H-alpha loop system and the acceleration process of material inside such loops

  4. Suppression of thermal noise in a non-Markovian random velocity field

    International Nuclear Information System (INIS)

    Ueda, Masahiko

    2016-01-01

    We study the diffusion of Brownian particles in a Gaussian random velocity field with short memory. By extending the derivation of an effective Fokker–Planck equation for the Lanvegin equation with weakly colored noise to a random velocity-field problem, we find that the effect of thermal noise on particles is suppressed by the existence of memory. We also find that the renormalization effect for the relative diffusion of two particles is stronger than that for single-particle diffusion. The results are compared with those of molecular dynamics simulations. (paper: classical statistical mechanics, equilibrium and non-equilibrium)

  5. Footpoint detection and mass-motion in chromospheric filaments

    Science.gov (United States)

    V, Aparna; Hardersen, P. S.; Martin, S. F.

    2013-07-01

    A quiescent region on the Sun containing three filaments is used to study the properties of mass motion. This study determines if the footpoints or end-points of the filaments are the locations from where mass gets injected into the filaments. Several hypotheses have been put forth in the past to determine how a filament acquires mass. Trapping of coronal mass in the filament channel due to condensation (Martin, 1996) and injection of mass into the filaments during magnetic reconnection (Priest, et al., 1995) are some of the speculations. This study looks for indications for injection of mass via chromospheric footpoints. The data consists of blue (Hα-0.5 Å) and red (Hα+0.5 Å) wing high resolution Hα images of the W29N37 region of the Sun taken on Oct 30, 2010, from 1200 - 1600 UT. The Dutch Open Telescope was used to obtain the data. The images are aligned and animated to see Doppler motion in the fibrils. Smaller fibrils merge to form longer ones; barbs appear and disappear in one of the long filaments and is seen moving along the length of the filament. A region with no typical filament-like absorption feature is observed to be continuously receiving mass. Fibrils appear to be converging from opposite sides along what appears to be a neutral line; mass motion is seen in these fibrils as well. An eruption occurs in a region of fibrils lumped together at the end of the first hour (1300 UT) followed by plage brightening at 1430 UT near one of the filament regions. Helioviewer (Panasenco, et al., 2011) is used for aligning the images; GIMP is used for precision alignment and animation. Each frame in the sequence is studied carefully to note changes in the filament regions. The footpoints of the filaments are determined by the changes observed in the position of the filament ‘legs’ in each frame. Variations in the magnetic polarity corresponding to changes observed in the chromosphere are analyzed using HMI magnetograms. Bright and dark points on the

  6. Estimating random transverse velocities in the fast solar wind from EISCAT Interplanetary Scintillation measurements

    Directory of Open Access Journals (Sweden)

    A. Canals

    2002-09-01

    Full Text Available Interplanetary scintillation measurements can yield estimates of a large number of solar wind parameters, including bulk flow speed, variation in bulk velocity along the observing path through the solar wind and random variation in transverse velocity. This last parameter is of particular interest, as it can indicate the flux of low-frequency Alfvén waves, and the dissipation of these waves has been proposed as an acceleration mechanism for the fast solar wind. Analysis of IPS data is, however, a significantly unresolved problem and a variety of a priori assumptions must be made in interpreting the data. Furthermore, the results may be affected by the physical structure of the radio source and by variations in the solar wind along the scintillation ray path. We have used observations of simple point-like radio sources made with EISCAT between 1994 and 1998 to obtain estimates of random transverse velocity in the fast solar wind. The results obtained with various a priori assumptions made in the analysis are compared, and we hope thereby to be able to provide some indication of the reliability of our estimates of random transverse velocity and the variation of this parameter with distance from the Sun.Key words. Interplanetary physics (MHD waves and turbulence; solar wind plasma; instruments and techniques

  7. Estimating random transverse velocities in the fast solar wind from EISCAT Interplanetary Scintillation measurements

    Directory of Open Access Journals (Sweden)

    A. Canals

    Full Text Available Interplanetary scintillation measurements can yield estimates of a large number of solar wind parameters, including bulk flow speed, variation in bulk velocity along the observing path through the solar wind and random variation in transverse velocity. This last parameter is of particular interest, as it can indicate the flux of low-frequency Alfvén waves, and the dissipation of these waves has been proposed as an acceleration mechanism for the fast solar wind. Analysis of IPS data is, however, a significantly unresolved problem and a variety of a priori assumptions must be made in interpreting the data. Furthermore, the results may be affected by the physical structure of the radio source and by variations in the solar wind along the scintillation ray path. We have used observations of simple point-like radio sources made with EISCAT between 1994 and 1998 to obtain estimates of random transverse velocity in the fast solar wind. The results obtained with various a priori assumptions made in the analysis are compared, and we hope thereby to be able to provide some indication of the reliability of our estimates of random transverse velocity and the variation of this parameter with distance from the Sun.

    Key words. Interplanetary physics (MHD waves and turbulence; solar wind plasma; instruments and techniques

  8. Three-dimensional distribution of random velocity inhomogeneities at the Nankai trough seismogenic zone

    Science.gov (United States)

    Takahashi, T.; Obana, K.; Yamamoto, Y.; Nakanishi, A.; Kaiho, Y.; Kodaira, S.; Kaneda, Y.

    2012-12-01

    The Nankai trough in southwestern Japan is a convergent margin where the Philippine sea plate is subducted beneath the Eurasian plate. There are major faults segments of huge earthquakes that are called Tokai, Tonankai and Nankai earthquakes. According to the earthquake occurrence history over the past hundreds years, we must expect various rupture patters such as simultaneous or nearly continuous ruptures of plural fault segments. Japan Agency for Marine-Earth Science and Technology (JAMSTEC) conducted seismic surveys at Nankai trough in order to clarify mutual relations between seismic structures and fault segments, as a part of "Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes" funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. This study evaluated the spatial distribution of random velocity inhomogeneities from Hyuga-nada to Kii-channel by using velocity seismograms of small and moderate sized earthquakes. Random velocity inhomogeneities are estimated by the peak delay time analysis of S-wave envelopes (e.g., Takahashi et al. 2009). Peak delay time is defined as the time lag from the S-wave onset to its maximal amplitude arrival. This quantity mainly reflects the accumulated multiple forward scattering effect due to random inhomogeneities, and is quite insensitive to the inelastic attenuation. Peak delay times are measured from the rms envelopes of horizontal components at 4-8Hz, 8-16Hz and 16-32Hz. This study used the velocity seismograms that are recorded by 495 ocean bottom seismographs and 378 onshore seismic stations. Onshore stations are composed of the F-net and Hi-net stations that are maintained by National Research Institute for Earth Science and Disaster Prevention (NIED) of Japan. It is assumed that the random inhomogeneities are represented by the von Karman type PSDF. Preliminary result of inversion analysis shows that spectral gradient of PSDF (i.e., scale dependence of

  9. Conditional random slope: A new approach for estimating individual child growth velocity in epidemiological research.

    Science.gov (United States)

    Leung, Michael; Bassani, Diego G; Racine-Poon, Amy; Goldenberg, Anna; Ali, Syed Asad; Kang, Gagandeep; Premkumar, Prasanna S; Roth, Daniel E

    2017-09-10

    Conditioning child growth measures on baseline accounts for regression to the mean (RTM). Here, we present the "conditional random slope" (CRS) model, based on a linear-mixed effects model that incorporates a baseline-time interaction term that can accommodate multiple data points for a child while also directly accounting for RTM. In two birth cohorts, we applied five approaches to estimate child growth velocities from 0 to 12 months to assess the effect of increasing data density (number of measures per child) on the magnitude of RTM of unconditional estimates, and the correlation and concordance between the CRS and four alternative metrics. Further, we demonstrated the differential effect of the choice of velocity metric on the magnitude of the association between infant growth and stunting at 2 years. RTM was minimally attenuated by increasing data density for unconditional growth modeling approaches. CRS and classical conditional models gave nearly identical estimates with two measures per child. Compared to the CRS estimates, unconditional metrics had moderate correlation (r = 0.65-0.91), but poor agreement in the classification of infants with relatively slow growth (kappa = 0.38-0.78). Estimates of the velocity-stunting association were the same for CRS and classical conditional models but differed substantially between conditional versus unconditional metrics. The CRS can leverage the flexibility of linear mixed models while addressing RTM in longitudinal analyses. © 2017 The Authors American Journal of Human Biology Published by Wiley Periodicals, Inc.

  10. Homogenization for rigid suspensions with random velocity-dependent interfacial forces

    KAUST Repository

    Gorb, Yuliya

    2014-12-01

    We study suspensions of solid particles in a viscous incompressible fluid in the presence of random velocity-dependent interfacial forces. The flow at a small Reynolds number is modeled by the Stokes equations, coupled with the motion of rigid particles arranged in a periodic array. The objective is to perform homogenization for the given suspension and obtain an equivalent description of a homogeneous (effective) medium, the macroscopic effect of the interfacial forces and the effective viscosity are determined using the analysis on a periodicity cell. In particular, the solutions uωε to a family of problems corresponding to the size of microstructure ε and describing suspensions of rigid particles with random surface forces imposed on the interface, converge H1-weakly as ε→0 a.s. to a solution of a Stokes homogenized problem, with velocity dependent body forces. A corrector to a homogenized solution that yields a strong H1-convergence is also determined. The main technical construction is built upon the Γ-convergence theory. © 2014 Elsevier Inc.

  11. Hindrance Velocity Model for Phase Segregation in Suspensions of Poly-dispersed Randomly Oriented Spheroids

    Science.gov (United States)

    Faroughi, S. A.; Huber, C.

    2015-12-01

    Crystal settling and bubbles migration in magmas have significant effects on the physical and chemical evolution of magmas. The rate of phase segregation is controlled by the force balance that governs the migration of particles suspended in the melt. The relative velocity of a single particle or bubble in a quiescent infinite fluid (melt) is well characterized; however, the interplay between particles or bubbles in suspensions and emulsions and its effect on their settling/rising velocity remains poorly quantified. We propose a theoretical model for the hindered velocity of non-Brownian emulsions of nondeformable droplets, and suspensions of spherical solid particles in the creeping flow regime. The model is based on three sets of hydrodynamic corrections: two on the drag coefficient experienced by each particle to account for both return flow and Smoluchowski effects and a correction on the mixture rheology to account for nonlocal interactions between particles. The model is then extended for mono-disperse non-spherical solid particles that are randomly oriented. The non-spherical particles are idealized as spheroids and characterized by their aspect ratio. The poly-disperse nature of natural suspensions is then taken into consideration by introducing an effective volume fraction of particles for each class of mono-disperse particles sizes. Our model is tested against new and published experimental data over a wide range of particle volume fraction and viscosity ratios between the constituents of dispersions. We find an excellent agreement between our model and experiments. We also show two significant applications for our model: (1) We demonstrate that hindered settling can increase mineral residence time by up to an order of magnitude in convecting magma chambers. (2) We provide a model to correct for particle interactions in the conventional hydrometer test to estimate the particle size distribution in soils. Our model offers a greatly improved agreement with

  12. Scaling of peak flows with constant flow velocity in random self-similar networks

    Directory of Open Access Journals (Sweden)

    R. Mantilla

    2011-07-01

    Full Text Available A methodology is presented to understand the role of the statistical self-similar topology of real river networks on scaling, or power law, in peak flows for rainfall-runoff events. We created Monte Carlo generated sets of ensembles of 1000 random self-similar networks (RSNs with geometrically distributed interior and exterior generators having parameters pi and pe, respectively. The parameter values were chosen to replicate the observed topology of real river networks. We calculated flow hydrographs in each of these networks by numerically solving the link-based mass and momentum conservation equation under the assumption of constant flow velocity. From these simulated RSNs and hydrographs, the scaling exponents β and φ characterizing power laws with respect to drainage area, and corresponding to the width functions and flow hydrographs respectively, were estimated. We found that, in general, φ > β, which supports a similar finding first reported for simulations in the river network of the Walnut Gulch basin, Arizona. Theoretical estimation of β and φ in RSNs is a complex open problem. Therefore, using results for a simpler problem associated with the expected width function and expected hydrograph for an ensemble of RSNs, we give heuristic arguments for theoretical derivations of the scaling exponents β(E and φ(E that depend on the Horton ratios for stream lengths and areas. These ratios in turn have a known dependence on the parameters of the geometric distributions of RSN generators. Good agreement was found between the analytically conjectured values of β(E and φ(E and the values estimated by the simulated ensembles of RSNs and hydrographs. The independence of the scaling exponents φ(E and φ with respect to the value of flow velocity and runoff intensity implies an interesting connection between unit

  13. Scaling of peak flows with constant flow velocity in random self-similar networks

    Science.gov (United States)

    Troutman, Brent M.; Mantilla, Ricardo; Gupta, Vijay K.

    2011-01-01

    A methodology is presented to understand the role of the statistical self-similar topology of real river networks on scaling, or power law, in peak flows for rainfall-runoff events. We created Monte Carlo generated sets of ensembles of 1000 random self-similar networks (RSNs) with geometrically distributed interior and exterior generators having parameters pi and pe, respectively. The parameter values were chosen to replicate the observed topology of real river networks. We calculated flow hydrographs in each of these networks by numerically solving the link-based mass and momentum conservation equation under the assumption of constant flow velocity. From these simulated RSNs and hydrographs, the scaling exponents β and φ characterizing power laws with respect to drainage area, and corresponding to the width functions and flow hydrographs respectively, were estimated. We found that, in general, φ > β, which supports a similar finding first reported for simulations in the river network of the Walnut Gulch basin, Arizona. Theoretical estimation of β and φ in RSNs is a complex open problem. Therefore, using results for a simpler problem associated with the expected width function and expected hydrograph for an ensemble of RSNs, we give heuristic arguments for theoretical derivations of the scaling exponents β(E) and φ(E) that depend on the Horton ratios for stream lengths and areas. These ratios in turn have a known dependence on the parameters of the geometric distributions of RSN generators. Good agreement was found between the analytically conjectured values of β(E) and φ(E) and the values estimated by the simulated ensembles of RSNs and hydrographs. The independence of the scaling exponents φ(E) and φ with respect to the value of flow velocity and runoff intensity implies an interesting connection between unit hydrograph theory and flow dynamics. Our results provide a reference framework to study scaling exponents under more complex scenarios

  14. Uncertainty on PIV mean and fluctuating velocity due to bias and random errors

    International Nuclear Information System (INIS)

    Wilson, Brandon M; Smith, Barton L

    2013-01-01

    Particle image velocimetry is a powerful and flexible fluid velocity measurement tool. In spite of its widespread use, the uncertainty of PIV measurements has not been sufficiently addressed to date. The calculation and propagation of local, instantaneous uncertainties on PIV results into the measured mean and Reynolds stresses are demonstrated for four PIV error sources that impact uncertainty through the vector computation: particle image density, diameter, displacement and velocity gradients. For the purpose of this demonstration, velocity data are acquired in a rectangular jet. Hot-wire measurements are compared to PIV measurements with velocity fields computed using two PIV algorithms. Local uncertainty on the velocity mean and Reynolds stress for these algorithms are automatically estimated using a previously published method. Previous work has shown that PIV measurements can become ‘noisy’ in regions of high shear as well as regions of small displacement. This paper also demonstrates the impact of these effects by comparing PIV data to data acquired using hot-wire anemometry, which does not suffer from the same issues. It is confirmed that flow gradients, large particle images and insufficient particle image displacements can result in elevated measurements of turbulence levels. The uncertainty surface method accurately estimates the difference between hot-wire and PIV measurements for most cases. The uncertainty based on each algorithm is found to be unique, motivating the use of algorithm-specific uncertainty estimates. (paper)

  15. Unsupervised Learning Through Randomized Algorithms for High-Volume High-Velocity Data (ULTRA-HV).

    Energy Technology Data Exchange (ETDEWEB)

    Pinar, Ali [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kolda, Tamara G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carlberg, Kevin Thomas [Wake Forest Univ., Winston-Salem, MA (United States); Ballard, Grey [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mahoney, Michael [Univ. of California, Berkeley, CA (United States)

    2018-01-01

    Through long-term investments in computing, algorithms, facilities, and instrumentation, DOE is an established leader in massive-scale, high-fidelity simulations, as well as science-leading experimentation. In both cases, DOE is generating more data than it can analyze and the problem is intensifying quickly. The need for advanced algorithms that can automatically convert the abundance of data into a wealth of useful information by discovering hidden structures is well recognized. Such efforts however, are hindered by the massive volume of the data and its high velocity. Here, the challenge is developing unsupervised learning methods to discover hidden structure in high-volume, high-velocity data.

  16. Remote Numerical Simulations of the Interaction of High Velocity Clouds with Random Magnetic Fields

    Science.gov (United States)

    Santillan, Alfredo; Hernandez--Cervantes, Liliana; Gonzalez--Ponce, Alejandro; Kim, Jongsoo

    The numerical simulations associated with the interaction of High Velocity Clouds (HVC) with the Magnetized Galactic Interstellar Medium (ISM) are a powerful tool to describe the evolution of the interaction of these objects in our Galaxy. In this work we present a new project referred to as Theoretical Virtual i Observatories. It is oriented toward to perform numerical simulations in real time through a Web page. This is a powerful astrophysical computational tool that consists of an intuitive graphical user interface (GUI) and a database produced by numerical calculations. In this Website the user can make use of the existing numerical simulations from the database or run a new simulation introducing initial conditions such as temperatures, densities, velocities, and magnetic field intensities for both the ISM and HVC. The prototype is programmed using Linux, Apache, MySQL, and PHP (LAMP), based on the open source philosophy. All simulations were performed with the MHD code ZEUS-3D, which solves the ideal MHD equations by finite differences on a fixed Eulerian mesh. Finally, we present typical results that can be obtained with this tool.

  17. Errors due to random noise in velocity measurement using incoherent-scatter radar

    Directory of Open Access Journals (Sweden)

    P. J. S. Williams

    1996-12-01

    Full Text Available The random-noise errors involved in measuring the Doppler shift of an 'incoherent-scatter' spectrum are predicted theoretically for all values of Te/Ti from 1.0 to 3.0. After correction has been made for the effects of convolution during transmission and reception and the additional errors introduced by subtracting the average of the background gates, the rms errors can be expressed by a simple semi-empirical formula. The observed errors are determined from a comparison of simultaneous EISCAT measurements using an identical pulse code on several adjacent frequencies. The plot of observed versus predicted error has a slope of 0.991 and a correlation coefficient of 99.3%. The prediction also agrees well with the mean of the error distribution reported by the standard EISCAT analysis programme.

  18. Simulating Pre-Asymptotic, Non-Fickian Transport Although Doing Simple Random Walks - Supported By Empirical Pore-Scale Velocity Distributions and Memory Effects

    Science.gov (United States)

    Most, S.; Jia, N.; Bijeljic, B.; Nowak, W.

    2016-12-01

    Pre-asymptotic characteristics are almost ubiquitous when analyzing solute transport processes in porous media. These pre-asymptotic aspects are caused by spatial coherence in the velocity field and by its heterogeneity. For the Lagrangian perspective of particle displacements, the causes of pre-asymptotic, non-Fickian transport are skewed velocity distribution, statistical dependencies between subsequent increments of particle positions (memory) and dependence between the x, y and z-components of particle increments. Valid simulation frameworks should account for these factors. We propose a particle tracking random walk (PTRW) simulation technique that can use empirical pore-space velocity distributions as input, enforces memory between subsequent random walk steps, and considers cross dependence. Thus, it is able to simulate pre-asymptotic non-Fickian transport phenomena. Our PTRW framework contains an advection/dispersion term plus a diffusion term. The advection/dispersion term produces time-series of particle increments from the velocity CDFs. These time series are equipped with memory by enforcing that the CDF values of subsequent velocities change only slightly. The latter is achieved through a random walk on the axis of CDF values between 0 and 1. The virtual diffusion coefficient for that random walk is our only fitting parameter. Cross-dependence can be enforced by constraining the random walk to certain combinations of CDF values between the three velocity components in x, y and z. We will show that this modelling framework is capable of simulating non-Fickian transport by comparison with a pore-scale transport simulation and we analyze the approach to asymptotic behavior.

  19. The Effect of Material Property on the Critical Velocity of Randomly Excited Nonlinear Axially Travelling Functionally Graded Plates

    Directory of Open Access Journals (Sweden)

    M. Abedi

    Full Text Available Abstract In this paper, the critical axial speeds of three types of sigmoid, power law and exponential law functionally graded plates for both isotropic and orthotropic cases are obtained via a completely analytic method. The plates are subjected to lateral white noise excitation and show evidence of large deformations. Due to randomness, the conventional deterministic methods fail and a statistical approach must be selected. Here, the probability density function is evaluated analytically for prescribed plates and used to investigate the critical axial velocity of them. Specifically the effect of in-plane forces, mean value of lateral load and the material property on the critical axial speed are studied and discussed for both isotropic and orthotropic functionally graded plates. Since the governing equation is transformed to a non dimensional format, the results can be used for a wide range of plate dimensions. It is shown that the material heterogeneity palys an essential and significant role in increasing or decreasing the critical speed of both isotropic and orthotropic functionally graded plates.

  20. CHROMOSPHERIC MASS MOTIONS AND INTRINSIC SUNSPOT ROTATIONS FOR NOAA ACTIVE REGIONS 10484, 10486, AND 10488 USING ISOON DATA

    International Nuclear Information System (INIS)

    Hardersen, Paul S.; Balasubramaniam, K. S.; Shkolyar, Svetlana

    2013-01-01

    This work utilizes Improved Solar Observing Optical Network continuum (630.2 nm) and Hα (656.2 nm) data to: (1) detect and measure intrinsic sunspot rotations occurring in the photosphere and chromosphere, (2) identify and measure chromospheric filament mass motions, and (3) assess any large-scale photospheric and chromospheric mass couplings. Significant results from 2003 October 27-29, using the techniques of Brown et al., indicate significant counter-rotation between the two large sunspots in NOAA AR 10486 on October 29, as well as discrete filament mass motions in NOAA AR 10484 on October 27 that appear to be associated with at least one C-class solar flare

  1. Elucidating fluctuating diffusivity in center-of-mass motion of polymer models with time-averaged mean-square-displacement tensor

    Science.gov (United States)

    Miyaguchi, Tomoshige

    2017-10-01

    There have been increasing reports that the diffusion coefficient of macromolecules depends on time and fluctuates randomly. Here a method is developed to elucidate this fluctuating diffusivity from trajectory data. Time-averaged mean-square displacement (MSD), a common tool in single-particle-tracking (SPT) experiments, is generalized to a second-order tensor with which both magnitude and orientation fluctuations of the diffusivity can be clearly detected. This method is used to analyze the center-of-mass motion of four fundamental polymer models: the Rouse model, the Zimm model, a reptation model, and a rigid rodlike polymer. It is found that these models exhibit distinctly different types of magnitude and orientation fluctuations of diffusivity. This is an advantage of the present method over previous ones, such as the ergodicity-breaking parameter and a non-Gaussian parameter, because with either of these parameters it is difficult to distinguish the dynamics of the four polymer models. Also, the present method of a time-averaged MSD tensor could be used to analyze trajectory data obtained in SPT experiments.

  2. Mass motions in impulsive flarelike brightenings as observed by OSO 8

    International Nuclear Information System (INIS)

    Bruner, E.C. Jr.; Lites, B.W.

    1979-01-01

    CIV lambda1548 line profiles obtained with the University of Colorado spectrometer aboard OSO 8 reveal transient, redshifted brightenings in the chromosphere-corona transition region above active regions and sunspots. In these events the intensity rises by factors of up to 5 in less than the profile sampling interval of 27 s. These events indicate that the emitting material is moving downward at velocities of up to 30 km s -1 . The increase in line intensity and the amount of motion are consistent with the interpretation of these events as pressure waves propagating down magnetic flux loops

  3. Mass motions in impulsive flarelike brightenings as observed by OSO 8. [mechanism response for solar flares

    Science.gov (United States)

    Bruner, E. C., Jr.; Lites, B. W.

    1979-01-01

    C IV 1548-A line profiles obtained with the University of Colorado spectrometer aboard OSO 8 reveal transient, redshifted brightenings in the chromosphere-corona transition region above active regions and sunspots. In these events the intensity rises by factors of up to 5 in less than the profile sampling interval of 27 sec. These events indicate that the emitting material is moving downward at velocities of up to 30 km/sec. The increase in line intensity and the amount of motion are consistent with the interpretation of these events as pressure waves propagating down magnetic flux loops.

  4. Computer simulation of different designs of pseudo-random time-of-flight velocity analysers for molecular beam scattering experiments

    International Nuclear Information System (INIS)

    Rotzoll, G.

    1982-01-01

    After a brief summary of the pseudo-random time-of-flight (TOF) method, the design criteria for construction of a pseudo-random TOF disc are considered and complemented by computer simulations. The question of resolution and the choice of the sequence length and number of time channels per element are discussed. Moreover, the stability requirements of the chopper motor frequency are investigated. (author)

  5. The Effects of Taekwondo Training on Peripheral Neuroplasticity-Related Growth Factors, Cerebral Blood Flow Velocity, and Cognitive Functions in Healthy Children: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Su-Youn Cho

    2017-04-01

    Full Text Available Although regular Taekwondo (TKD training has been reported to be effective for improving cognitive function in children, the mechanism underlying this improvement remains unclear. The purpose of the present study was to observe changes in neuroplasticity-related growth factors in the blood, assess cerebral blood flow velocity, and verify the resulting changes in children’s cognitive function after TKD training. Thirty healthy elementary school students were randomly assigned to control (n = 15 and TKD (n = 15 groups. The TKD training was conducted for 60 min at a rating of perceived exertion (RPE of 11–15, 5 times per week, for 16 weeks. Brain-derived neurotrophic factor (BDNF, vascular endothelial growth factor (VEGF, and insulin-like growth factor-1 (IGF-1 levels were measured by blood sampling before and after the training, and the cerebral blood flow velocities (peak systolic [MCAs], end diastolic [MCAd], mean cerebral blood flow velocities [MCAm], and pulsatility index [PI] of the middle cerebral artery (MCA were measured using Doppler ultrasonography. For cognitive function assessment, Stroop Color and Word Tests (Word, Color, and Color-Word were administered along with other measurements. The serum BDNF, VEGF, and IGF-1 levels and the Color-Word test scores among the sub-factors of the Stroop Color and Word Test scores were significantly higher in the TKD group after the intervention (p < 0.05. On the other hand, no statistically significant differences were found in any factors related to cerebral blood flow velocities, or in the Word test and Color test scores (p > 0.05. Thus, 16-week TKD training did not significantly affect cerebral blood flow velocities, but the training may have been effective in increasing children’s cognitive function by inducing an increase in the levels of neuroplasticity-related growth factors.

  6. Cooling the center-of-mass motion of a diamond nanocrystal in a magneto-gravitational trap

    Science.gov (United States)

    Hsu, Jen-Feng

    A magneto-gravitational trap for micro/nanometer sized diamagnetic particles, such as diamond nanocrystals, is tested and characterized. After exploring various other systems, such as a suspended graphene beam and an optical trap, this magneto-gravitational nanomechanical trapping system for diamond with nitrogen-vacancy (NV) centers presents unique advantages for experiments in fundamental quantum mechanics. Those include, for example, the generation of large quantum superposition states and tests of quantum gravity. Features are demonstrated for this system, such as stable and passive levitation from atmospheric pressure to high vacuum, low resonant frequencies and damping rates, and cooling of the center-of-mass motions to below 1 K. The construction of the trap, vacuum system, optics, and motion detection electronics are described in detail.

  7. Improved Pulse Wave Velocity and Renal Function in Individualized Calcineurin Inhibitor Treatment by Immunomonitoring: The Randomized Controlled Calcineurin Inhibitor-Sparing Trial.

    Science.gov (United States)

    Sommerer, Claudia; Brocke, Janina; Bruckner, Thomas; Schaier, Matthias; Morath, Christian; Meuer, Stefan; Zeier, Martin; Giese, Thomas

    2018-03-01

    A new immune monitoring tool which assesses the expression of nuclear factor of activated T cells (NFAT)-regulated genes measures the functional effects of cyclosporine A. This is the first prospective randomized controlled study to compare standard pharmacokinetic monitoring by cyclosporine trough levels to NFAT-regulated gene expression (NFAT-RE). Expression of the NFAT-regulated genes was determined by qRT-PCR at cyclosporine trough and peak level. Cardiovascular risk was assessed by change of pulse wave velocity from baseline to month 6. Clinical follow-up was 12 months. In total, 55 stable kidney allograft recipients were enrolled. Mean baseline residual NFAT-RE was 13.1 ± 9.1%. Patients in the NFAT-RE group showed a significant decline in pulse wave velocity from baseline to month 6 versus the standard group (-1.7 ± 2.0 m/s vs 0.4 ± 1.4 m/s, P function was significantly better with NFAT-RE versus standard monitoring (Nankivell glomerular filtration rate: 68.5 ± 17.4 mL/min vs 57.2 ± 19.0 mL/min; P = 0.009). NFAT-RE as translational immune monitoring tool proved efficacious and safe in individualizing cyclosporine therapy, with the opportunity to reduce the cardiovascular risk and improve long-term renal allograft function.

  8. PSA velocity does not aid the detection of prostate cancer in men with a prior negative biopsy: data from the European Randomized Study of Prostate Cancer Screening in Göteborg, Sweden and Rotterdam, Netherlands

    Science.gov (United States)

    Vickers, Andrew J.; Wolters, Tineke; Savage, Caroline J.; Cronin, Angel M.; O’Brien, M. Frank; Roobol, Monique J.; Aus, Gunnar; Scardino, Peter T.; Hugosson, Jonas; Schröder, Fritz H.; Lilja, Hans

    2012-01-01

    Purpose Prostate specific antigen (PSA) velocity has been proposed as a marker to aid detection of prostate cancer. We sought to determine whether PSA velocity could predict the results of repeat biopsy in men with persistently elevated PSA after initial negative biopsy. Materials and Methods We identified 1,837 men who participated in the Göteborg or Rotterdam section of the European Randomized Screening study of Prostate Cancer (ERSPC), and who had one or more subsequent prostate biopsies after an initial negative finding. We evaluated whether PSA velocity improved predictive accuracy beyond that of PSA alone. Results There were a total of 2579 repeat biopsies, of which 363 (14%) were positive for prostate cancer, and 44 (1.7%) were high grade (Gleason score ≥7). Although PSA velocity was statistically associated with cancer risk (p<0.001), it had very low predictive accuracy (area-under-the-curve [AUC] of 0.55). There was some evidence that PSA velocity improved AUC compared to PSA for high grade cancer. However, the small increase in risk associated with high PSA velocity – from 1.7 % to 2.8% as velocity increased from 0 to 1 ng / ml / year - is of questionable clinical relevance. Conclusions Men with a prior negative biopsy have a lower risk for prostate cancer at subsequent biopsies, with high grade disease particularly rare. We found little evidence to support the use of PSA velocity to aid decisions about repeat biopsy for prostate cancer. PMID:20643434

  9. A randomized, controlled, double-blind crossover study on the effects of 2-L infusions of 0.9% saline and plasma-lyte® 148 on renal blood flow velocity and renal cortical tissue perfusion in healthy volunteers.

    Science.gov (United States)

    Chowdhury, Abeed H; Cox, Eleanor F; Francis, Susan T; Lobo, Dileep N

    2012-07-01

    We compared the effects of intravenous infusions of 0.9% saline ([Cl] 154 mmol/L) and Plasma-Lyte 148 ([Cl] 98 mmol/L, Baxter Healthcare) on renal blood flow velocity and perfusion in humans using magnetic resonance imaging (MRI). Animal experiments suggest that hyperchloremia resulting from 0.9% saline infusion may affect renal hemodynamics adversely, a phenomenon not studied in humans. Twelve healthy adult male subjects received 2-L intravenous infusions over 1 hour of 0.9% saline or Plasma-Lyte 148 in a randomized, double-blind manner. Crossover studies were performed 7 to 10 days apart. MRI scanning proceeded for 90 minutes after commencement of infusion to measure renal artery blood flow velocity and renal cortical perfusion. Blood was sampled and weight recorded hourly for 4 hours. Sustained hyperchloremia was seen with saline but not with Plasma-Lyte 148 (P Blood volume changes were identical (P = 0.867), but there was greater expansion of the extravascular fluid volume after saline (P = 0.029). There was a significant reduction in mean renal artery flow velocity (P = 0.045) and renal cortical tissue perfusion (P = 0.008) from baseline after saline, but not after Plasma-Lyte 148. There was no difference in concentrations of urinary neutrophil gelatinase-associated lipocalin after the 2 infusions (P = 0.917). This is the first human study to demonstrate that intravenous infusion of 0.9% saline results in reductions in renal blood flow velocity and renal cortical tissue perfusion. This has implications for intravenous fluid therapy in perioperative and critically ill patients. NCT01087853.

  10. Surface flux transport simulations: Effect of inflows toward active regions and random velocities on the evolution of the Sun's large-scale magnetic field

    Science.gov (United States)

    Martin-Belda, D.; Cameron, R. H.

    2016-02-01

    Aims: We aim to determine the effect of converging flows on the evolution of a bipolar magnetic region (BMR), and to investigate the role of these inflows in the generation of poloidal flux. We also discuss whether the flux dispersal due to turbulent flows can be described as a diffusion process. Methods: We developed a simple surface flux transport model based on point-like magnetic concentrations. We tracked the tilt angle, the magnetic flux and the axial dipole moment of a BMR in simulations with and without inflows and compared the results. To test the diffusion approximation, simulations of random walk dispersal of magnetic features were compared against the predictions of the diffusion treatment. Results: We confirm the validity of the diffusion approximation to describe flux dispersal on large scales. We find that the inflows enhance flux cancellation, but at the same time affect the latitudinal separation of the polarities of the bipolar region. In most cases the latitudinal separation is limited by the inflows, resulting in a reduction of the axial dipole moment of the BMR. However, when the initial tilt angle of the BMR is small, the inflows produce an increase in latitudinal separation that leads to an increase in the axial dipole moment in spite of the enhanced flux destruction. This can give rise to a tilt of the BMR even when the BMR was originally aligned parallel to the equator.

  11. Stability aspects of plasmas penetrated by neutral gas with respect to velocity driven modes

    International Nuclear Information System (INIS)

    Ohlsson, D.

    1978-08-01

    A study of the stability properties of dense partially ionized plasmas immersed in strong magnetic fields with respect to velocity driven modes are presented. First we consider modes driven by mass motion perpendicular to the lines of force and the unperturbed density and temperature gradients. The presence of a third fluid, neutral gas, gives under certain conditions rise to unstable modes. This type of instability arises independently or whether the applied electric field transverse to the lines of force, driving the mass motion, being parallel or antiparallel to the unperturbed density and temperature gradient. The presence of neutral gas also corresponds to stabilizing effects which, in certain parameter regions, result in a quenching of this instability. It is shown that modes driven by velocity shear perpendicular to the lines of force are effectively stabilized by viscous and resistive effects. These effects are in certain parameter ranges strongly enhanced on account of plasma-neutral gas interaction effects. In collisionless plasmas, modes driven by velocity shear parallel to the lines of force are stabilized by compressibility effects parallel to the magnetic field and by finite Larmor radius effects. (author)

  12. Nerve conduction velocity

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003927.htm Nerve conduction velocity To use the sharing features on this page, please enable JavaScript. Nerve conduction velocity (NCV) is a test to see ...

  13. The velocity of sound

    International Nuclear Information System (INIS)

    Beyer, R.T.

    1985-01-01

    The paper reviews the work carried out on the velocity of sound in liquid alkali metals. The experimental methods to determine the velocity measurements are described. Tables are presented of reported data on the velocity of sound in lithium, sodium, potassium, rubidium and caesium. A formula is given for alkali metals, in which the sound velocity is a function of shear viscosity, atomic mass and atomic volume. (U.K.)

  14. Cosmic string induced peculiar velocities

    International Nuclear Information System (INIS)

    van Dalen, A.; Schramm, D.N.

    1987-02-01

    We calculate analytically the probability distribution for peculiar velocities on scales from 10h -1 to 60h -1 Mpc with cosmic string loops as the dominant source of primordial gravitational perturbations. We consider a range of parameters βGμ appropriate for both hot (HDM) and cold (CDM) dark matter scenarios. An Ω = 1 CDM Universe is assumed with the loops randomly placed on a smooth background. It is shown how the effects can be estimated of loops breaking up and being born with a spectrum of sizes. It is found that to obtain large scale streaming velocities of at least 400 km/s it is necessary that either a large value for βGμ or the effect of loop fissioning and production details be considerable. Specifically, for optimal CDM string parameters Gμ = 10 -6 , β = 9, h = .5, and scales of 60h -1 Mpc, the parent size spectrum must be 36 times larger than the evolved daughter spectrum to achieve peculiar velocities of at least 400 km/s with a probability of 63%. With this scenario the microwave background dipole will be less than 800 km/s with only a 10% probability. The string induced velocity spectrum is relatively flat out to scales of about 2t/sub eq//a/sub eq/ and then drops off rather quickly. The flatness is a signature of string models of galaxy formation. With HDM a larger value of βGμ is necessary for galaxy formation since accretion on small scales starts later. Hence, with HDM, the peculiar velocity spectrum will be larger on large scales and the flat region will extend to larger scales. If large scale peculiar velocities greater than 400 km/s are real then it is concluded that strings plus CDM have difficulties. The advantages of strings plus HDM in this regard will be explored in greater detail in a later paper. 27 refs., 4 figs., 1 tab

  15. Random electrodynamics : a classical foundation for key quantum concepts

    International Nuclear Information System (INIS)

    Sachidanandam, S.

    1981-01-01

    The model of random electrodynamics, in which electromagnetic particles are subjected, in a classical manner, to the forces of radiation damping and the fluctuating zero-point fields provides the framework in which the following results are obtained: (1) The precession dynamics of a long-lived, non-relativistic particle with a magnetic moment proportional to its spin, leads to a self-consistent determination of the spin value as one-half. (2) The internal dynamic underlying the intrinsic magnetic moment of a Dirac particle yields a classically visualizable picture of the spin-magnetic moment. (3) The Bose correlation among indistinguishable, non-interacting, spin-zero Particles arises from the coupling through the common- zero point fields and the radiation reaction fields when the particles are close together in both the r vector and the energy spaces. (4) The (exclusion principle-induced) correlation among identical, non-interacting magnetic particles with spin 1/2 is brought about by the coupling, (through the common fields of radiation reaction and the vacuum fluctuations), of the spins as well as the translational motions when the particles are close together in r vector and the energy spaces. (5) A dilute gas of free electrons has a Maxwellian distribution of velocities and the correct value of the djamagnetic moment in the presence of a magnetic field. Considerations on the centre of mass motion of a composite neutral particle lead to a simple resolution of the foundational paradoxes of statistical mechanics. (6) An approximate treatment of the hydrogen atom leads to a description of the evolution to the ground state at absolute zero and an estimation of the mass frequency and the line-width of the radiation emitted when an excited atom decays. (author)

  16. Water velocity meter

    Science.gov (United States)

    Roberts, C. W.; Smith, D. L.

    1970-01-01

    Simple, inexpensive drag sphere velocity meter with a zero to 6 ft/sec range measures steady-state flow. When combined with appropriate data acquisition system, it is suited to applications where large numbers of simultaneous measurements are needed for current mapping or velocity profile determination.

  17. 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...

  18. Velocity Feedback Experiments

    Directory of Open Access Journals (Sweden)

    Chiu Choi

    2017-02-01

    Full Text Available Transient response such as ringing in a control system can be reduced or removed by velocity feedback. It is a useful control technique that should be covered in the relevant engineering laboratory courses. We developed velocity feedback experiments using two different low cost technologies, viz., operational amplifiers and microcontrollers. These experiments can be easily integrated into laboratory courses on feedback control systems or microcontroller applications. The intent of developing these experiments was to illustrate the ringing problem and to offer effective, low cost solutions for removing such problem. In this paper the pedagogical approach for these velocity feedback experiments was described. The advantages and disadvantages of the two different implementation of velocity feedback were discussed also.

  19. The critical ionization velocity

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1980-06-01

    The critical ionization velocity effect was first proposed in the context of space plasmas. This effect occurs for a neutral gas moving through a magnetized plasma and leads to rapid ionization and braking of the relative motion when a marginal velocity, 'the critical velocity', is exceeded. Laboratory experiments have clearly established the significance of the critical velocity and have provided evidence for an underlying mechanism which relies on the combined action of electron impact ionization and a collective plasma interaction heating electrons. There is experimental support for such a mechanism based on the heating of electrons by the modified two-stream instability as part of a feedback process. Several applications to space plasmas have been proposed and the possibility of space experiments has been discussed. (author)

  20. High Velocity Gas Gun

    Science.gov (United States)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  1. Modified Feynman ratchet with velocity-dependent fluctuations

    Directory of Open Access Journals (Sweden)

    Jack Denur

    2004-03-01

    Full Text Available Abstract: The randomness of Brownian motion at thermodynamic equilibrium can be spontaneously broken by velocity-dependence of fluctuations, i.e., by dependence of values or probability distributions of fluctuating properties on Brownian-motional velocity. Such randomness-breaking can spontaneously obtain via interaction between Brownian-motional Doppler effects --- which manifest the required velocity-dependence --- and system geometrical asymmetry. A non random walk is thereby spontaneously superposed on Brownian motion, resulting in a systematic net drift velocity despite thermodynamic equilibrium. The time evolution of this systematic net drift velocity --- and of velocity probability density, force, and power output --- is derived for a velocity-dependent modification of Feynman's ratchet. We show that said spontaneous randomness-breaking, and consequent systematic net drift velocity, imply: bias from the Maxwellian of the system's velocity probability density, the force that tends to accelerate it, and its power output. Maximization, especially of power output, is discussed. Uncompensated decreases in total entropy, challenging the second law of thermodynamics, are thereby implied.

  2. Modified circular velocity law

    Science.gov (United States)

    Djeghloul, Nazim

    2018-05-01

    A modified circular velocity law is presented for a test body orbiting around a spherically symmetric mass. This law exhibits a distance scale parameter and allows to recover both usual Newtonian behaviour for lower distances and a constant velocity limit at large scale. Application to the Galaxy predicts the known behaviour and also leads to a galactic mass in accordance with the measured visible stellar mass so that additional dark matter inside the Galaxy can be avoided. It is also shown that this circular velocity law can be embedded in a geometrical description of spacetime within the standard general relativity framework upon relaxing the usual asymptotic flatness condition. This formulation allows to redefine the introduced Newtonian scale limit in term of the central mass exclusively. Moreover, a satisfactory answer to the galactic escape speed problem can be provided indicating the possibility that one can also get rid of dark matter halo outside the Galaxy.

  3. Keynesian multiplier versus velocity of money

    Science.gov (United States)

    Wang, Yougui; Xu, Yan; Liu, Li

    2010-08-01

    In this paper we present the relation between Keynesian multiplier and the velocity of money circulation in a money exchange model. For this purpose we modify the original exchange model by constructing the interrelation between income and expenditure. The random exchange yields an agent's income, which along with the amount of money he processed determines his expenditure. In this interactive process, both the circulation of money and Keynesian multiplier effect can be formulated. The equilibrium values of Keynesian multiplier are demonstrated to be closely related to the velocity of money. Thus the impacts of macroeconomic policies on aggregate income can be understood by concentrating solely on the variations of money circulation.

  4. 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...

  5. Multidisc neutron velocity selector

    International Nuclear Information System (INIS)

    Rosta, L.; Zsigmond, Gy.; Farago, B.; Mezei, F.; Ban, K.; Perendi, J.

    1987-12-01

    The prototype of a velocity selector for neutron monochromatization in the 4-20 A wavelength range is presented. The theoretical background of the multidisc rotor system is given together with a description of the mechanical construction and electronic driving system. The first tests and neutron measurements prove easy handling and excellent parameters. (author) 6 refs.; 7 figs.; 2 tabs

  6. Multidisk neutron velocity selectors

    International Nuclear Information System (INIS)

    Hammouda, B.

    1992-01-01

    Helical multidisk velocity selectors used for neutron scattering applications have been analyzed and tested experimentally. Design and performance considerations are discussed along with simple explanation of the basic concept. A simple progression is used for the inter-disk spacing in the 'Rosta' design. Ray tracing computer investigations are presented in order to assess the 'coverage' (how many absorbing layers are stacked along the path of 'wrong' wavelength neutrons) and the relative number of neutrons absorbed in each disk (and therefore the relative amount of gamma radiation emitted from each disk). We discuss whether a multidisk velocity selector can be operated in the 'reverse' configuration (i.e. the selector is turned by 180 0 around a vertical axis with the rotor spun in the reverse direction). Experimental tests and calibration of a multidisk selector are reported together with evidence that a multidisk selector can be operated in the 'reverse' configuration. (orig.)

  7. The Velocity Distribution of Isolated Radio Pulsars

    Science.gov (United States)

    Arzoumanian, Z.; Chernoff, D. F.; Cordes, J. M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We infer the velocity distribution of radio pulsars based on large-scale 0.4 GHz pulsar surveys. We do so by modelling evolution of the locations, velocities, spins, and radio luminosities of pulsars; calculating pulsed flux according to a beaming model and random orientation angles of spin and beam; applying selection effects of pulsar surveys; and comparing model distributions of measurable pulsar properties with survey data using a likelihood function. The surveys analyzed have well-defined characteristics and cover approx. 95% of the sky. We maximize the likelihood in a 6-dimensional space of observables P, dot-P, DM, absolute value of b, mu, F (period, period derivative, dispersion measure, Galactic latitude, proper motion, and flux density). The models we test are described by 12 parameters that characterize a population's birth rate, luminosity, shutoff of radio emission, birth locations, and birth velocities. We infer that the radio beam luminosity (i) is comparable to the energy flux of relativistic particles in models for spin-driven magnetospheres, signifying that radio emission losses reach nearly 100% for the oldest pulsars; and (ii) scales approximately as E(exp 1/2) which, in magnetosphere models, is proportional to the voltage drop available for acceleration of particles. We find that a two-component velocity distribution with characteristic velocities of 90 km/ s and 500 km/ s is greatly preferred to any one-component distribution; this preference is largely immune to variations in other population parameters, such as the luminosity or distance scale, or the assumed spin-down law. We explore some consequences of the preferred birth velocity distribution: (1) roughly 50% of pulsars in the solar neighborhood will escape the Galaxy, while approx. 15% have velocities greater than 1000 km/ s (2) observational bias against high velocity pulsars is relatively unimportant for surveys that reach high Galactic absolute value of z distances, but is severe for

  8. 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...

  9. A randomized, controlled, double-blind crossover study on the effects of 1-L infusions of 6% hydroxyethyl starch suspended in 0.9% saline (voluven) and a balanced solution (Plasma Volume Redibag) on blood volume, renal blood flow velocity, and renal cortical tissue perfusion in healthy volunteers.

    Science.gov (United States)

    Chowdhury, Abeed H; Cox, Eleanor F; Francis, Susan T; Lobo, Dileep N

    2014-05-01

    We compared the effects of intravenous administration of 6% hydroxyethyl starch (maize-derived) in 0.9% saline (Voluven; Fresenius Kabi, Runcorn, United Kingdom) and a "balanced" preparation of 6% hydroxyethyl starch (potato-derived) [Plasma Volume Redibag (PVR); Baxter Healthcare, Thetford, United Kingdom] on renal blood flow velocity and renal cortical tissue perfusion in humans using magnetic resonance imaging. Hyperchloremia resulting from 0.9% saline infusion may adversely affect renal hemodynamics when compared with balanced crystalloids. This phenomenon has not been studied with colloids. Twelve healthy adult male subjects received 1-L intravenous infusions of Voluven or PVR over 30 minutes in a randomized, double-blind manner, with crossover studies 7 to 10 days later. Magnetic resonance imaging proceeded for 60 minutes after commencement of infusion to measure renal artery blood flow velocity and renal cortical perfusion. Blood was sampled, and weight was recorded at 0, 30, 60, 120, 180, and 240 minutes. Mean peak serum chloride concentrations were 108 and 106 mmol/L, respectively, after Voluven and PVR infusion (P = 0.032). Changes in blood volume (P = 0.867), strong ion difference (P = 0.219), and mean renal artery flow velocity (P = 0.319) were similar. However, there was a significant increase in mean renal cortical tissue perfusion after PVR when compared with Voluven (P = 0.033). There was no difference in urinary neutrophil gelatinase-associated liopcalin to creatinine ratios after the infusion (P = 0.164). There was no difference in the blood volume-expanding properties of the 2 preparations of 6% hydroxyethyl starch. The balanced starch produced an increase in renal cortical tissue perfusion, a phenomenon not seen with starch in 0.9% saline.

  10. Thermophoresis as persistent random walk

    International Nuclear Information System (INIS)

    Plyukhin, A.V.

    2009-01-01

    In a simple model of a continuous random walk a particle moves in one dimension with the velocity fluctuating between +v and -v. If v is associated with the thermal velocity of a Brownian particle and allowed to be position dependent, the model accounts readily for the particle's drift along the temperature gradient and recovers basic results of the conventional thermophoresis theory.

  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. Cosmological streaming velocities and large-scale density maxima

    International Nuclear Information System (INIS)

    Peacock, J.A.; Lumsden, S.L.; Heavens, A.F.

    1987-01-01

    The statistical testing of models for galaxy formation against the observed peculiar velocities on 10-100 Mpc scales is considered. If it is assumed that observers are likely to be sited near maxima in the primordial field of density perturbations, then the observed filtered velocity field will be biased to low values by comparison with a point selected at random. This helps to explain how the peculiar velocities (relative to the microwave background) of the local supercluster and the Rubin-Ford shell can be so similar in magnitude. Using this assumption to predict peculiar velocities on two scales, we test models with large-scale damping (i.e. adiabatic perturbations). Allowed models have a damping length close to the Rubin-Ford scale and are mildly non-linear. Both purely baryonic universes and universes dominated by massive neutrinos can account for the observed velocities, provided 0.1 ≤ Ω ≤ 1. (author)

  13. Control rod velocity limiter

    International Nuclear Information System (INIS)

    Cearley, J.E.; Carruth, J.C.; Dixon, R.C.; Spencer, S.S.; Zuloaga, J.A. Jr.

    1986-01-01

    This patent describes a velocity control arrangement for a reciprocable, vertically oriented control rod for use in a nuclear reactor in a fluid medium, the control rod including a drive hub secured to and extending from one end therefrom. The control device comprises: a toroidally shaped control member spaced from and coaxially positioned around the hub and secured thereto by a plurality of spaced radial webs thereby providing an annular passage for fluid intermediate the hub and the toroidal member spaced therefrom in coaxial position. The side of the control member toward the control rod has a smooth generally conical surface. The side of the control member away from the control rod is formed with a concave surface constituting a single annular groove. The device also comprises inner and outer annular vanes radially spaced from one another and spaced from the side of the control member away from the control rod and positioned coaxially around and spaced from the hub and secured thereto by spaced radial webs thereby providing an annular passage for fluid intermediate the hub and the vanes. The vanes are angled toward the control member, the outer edge of the inner vane being closer to the control member and the inner edge of the outer vane being closer to the control member. When the control rod moves in the fluid in the direction toward the drive hub the vanes direct a flow of fluid turbulence which provides greater resistance to movement of the control rod in the direction toward the drive hub than in the other direction

  14. Velocity Dispersions Across Bulge Types

    International Nuclear Information System (INIS)

    Fabricius, Maximilian; Bender, Ralf; Hopp, Ulrich; Saglia, Roberto; Drory, Niv; Fisher, David

    2010-01-01

    We present first results from a long-slit spectroscopic survey of bulge kinematics in local spiral galaxies. Our optical spectra were obtained at the Hobby-Eberly Telescope with the LRS spectrograph and have a velocity resolution of 45 km/s (σ*), which allows us to resolve the velocity dispersions in the bulge regions of most objects in our sample. We find that the velocity dispersion profiles in morphological classical bulge galaxies are always centrally peaked while the velocity dispersion of morphologically disk-like bulges stays relatively flat towards the center--once strongly barred galaxies are discarded.

  15. On linear relationship between shock velocity and particle velocity

    International Nuclear Information System (INIS)

    Dandache, H.

    1986-11-01

    We attempt to derive the linear relationship between shock velocity U s and particle velocity U p from thermodynamic considerations, taking into account an ideal gas equation of state and a Mie-Grueneisen equation of state for solids. 23 refs

  16. 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.

  17. Introduction to vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Udesen, Jesper; Hansen, Kristoffer Lindskov

    Current ultrasound scanners can only estimate the velocity along the ultrasound beam and this gives rise to the cos() factor on all velocity estimates. This is a major limitation as most vessels are close to perpendicular to the beam. Also the angle varies as a function of space and time making ...

  18. 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.

  19. Radial velocity asymmetries from jets with variable velocity profiles

    International Nuclear Information System (INIS)

    Cerqueira, A. H.; Vasconcelos, M. J.; Velazquez, P. F.; Raga, A. C.; De Colle, F.

    2006-01-01

    We have computed a set of 3-D numerical simulations of radiatively cooling jets including variabilities in both the ejection direction (precession) and the jet velocity (intermittence), using the Yguazu-a code. In order to investigate the effects of jet rotation on the shape of the line profiles, we also introduce an initial toroidal rotation velocity profile. Since the Yguazu-a code includes an atomic/ionic network, we are able to compute the emission coefficients for several emission lines, and we generate line profiles for the Hα, [O I]λ6300, [S II]λ6716 and [N II]λ6548 lines. Using initial parameters that are suitable for the DG Tau microjet, we show that the computed radial velocity shift for the medium-velocity component of the line profile as a function of distance from the jet axis is strikingly similar for rotating and non-rotating jet models

  20. Fractals control in particle's velocity

    International Nuclear Information System (INIS)

    Zhang Yongping; Liu Shutang; Shen Shulan

    2009-01-01

    Julia set, a fractal set of the literature of nonlinear physics, has significance for the engineering applications. For example, the fractal structure characteristics of the generalized M-J set could visually reflect the change rule of particle's velocity. According to the real world requirement, the system need show various particle's velocity in some cases. Thus, the control of the nonlinear behavior, i.e., Julia set, has attracted broad attention. In this work, an auxiliary feedback control is introduced to effectively control the Julia set that visually reflects the change rule of particle's velocity. It satisfies the performance requirement of the real world problems.

  1. Southern high-velocity stars

    International Nuclear Information System (INIS)

    Augensen, H.J.; Buscombe, W.

    1978-01-01

    Using the model of the Galaxy presented by Eggen, Lynden-Bell and Sandage (1962), plane galactic orbits have been calculated for 800 southern high-velocity stars which possess parallax, proper motion, and radial velocity data. The stars with trigonometric parallaxes were selected from Buscombe and Morris (1958), supplemented by more recent spectroscopic data. Photometric parallaxes from infrared color indices were used for bright red giants studied by Eggen (1970), and for red dwarfs for which Rodgers and Eggen (1974) determined radial velocities. A color-color diagram based on published values of (U-B) and (B-V) for most of these stars is shown. (Auth.)

  2. Application of Migration Velocity Using Fourier Transform Approach ...

    African Journals Online (AJOL)

    Application of velocity by Fourier transform to process 3-D unmigrated seismic sections has been carried out in Fabi Field, Niger Delta – Nigeria. Usually, all seismic events (sections) are characterized by spikes or noise (random or coherent), multiples and shear waves so that when a seismic bed is dipping, the apparent ...

  3. Dispersion upscaling from a pore scale characterization of Lagrangian velocities

    Science.gov (United States)

    Turuban, Régis; de Anna, Pietro; Jiménez-Martínez, Joaquín; Tabuteau, Hervé; Méheust, Yves; Le Borgne, Tanguy

    2013-04-01

    Mixing and reactive transport are primarily controlled by the interplay between diffusion, advection and reaction at pore scale. Yet, how the distribution and spatial correlation of the velocity field at pore scale impact these processes is still an open question. Here we present an experimental investigation of the distribution and correlation of pore scale velocities and its relation with upscaled dispersion. We use a quasi two-dimensional (2D) horizontal set up, consisting of two glass plates filled with cylinders representing the grains of the porous medium : the cell is built by soft lithography technique, wich allows for full control of the system geometry. The local velocity field is quantified from particle tracking velocimetry using microspheres that are advected with the pore scale flow. Their displacement is purely advective, as the particle size is chosen large enough to avoid diffusion. We thus obtain particle trajectories as well as lagrangian velocities in the entire system. The measured velocity field shows the existence of a network of preferential flow paths in channels with high velocities, as well as very low velocity in stagnation zones, with a non Gaussian distribution. Lagrangian velocities are long range correlated in time, which implies a non-fickian scaling of the longitudinal variance of particle positions. To upscale this process we develop an effective transport model, based on correlated continous time random walk, which is entirely parametrized by the pore scale velocity distribution and correlation. The model predictions are compared with conservative tracer test data for different Peclet numbers. Furthermore, we investigate the impact of different pore geometries on the distribution and correlation of Lagrangian velocities and we discuss the link between these properties and the effective dispersion behavior.

  4. Sound Velocity in Soap Foams

    International Nuclear Information System (INIS)

    Wu Gong-Tao; Lü Yong-Jun; Liu Peng-Fei; Li Yi-Ning; Shi Qing-Fan

    2012-01-01

    The velocity of sound in soap foams at high gas volume fractions is experimentally studied by using the time difference method. It is found that the sound velocities increase with increasing bubble diameter, and asymptotically approach to the value in air when the diameter is larger than 12.5 mm. We propose a simple theoretical model for the sound propagation in a disordered foam. In this model, the attenuation of a sound wave due to the scattering of the bubble wall is equivalently described as the effect of an additional length. This simplicity reasonably reproduces the sound velocity in foams and the predicted results are in good agreement with the experiments. Further measurements indicate that the increase of frequency markedly slows down the sound velocity, whereas the latter does not display a strong dependence on the solution concentration

  5. Settling velocities in batch sedimentation

    International Nuclear Information System (INIS)

    Fricke, A.M.; Thompson, B.E.

    1982-10-01

    The sedimentation of mixtures containing one and two sizes of spherical particles (44 and 62 μm in diameter) was studied. Radioactive tracing with 57 Co was used to measure the settling velocities. The ratio of the settling velocity U of uniformly sized particles to the velocity predicted to Stokes' law U 0 was correlated to an expression of the form U/U 0 = epsilon/sup α/, where epsilon is the liquid volume fraction and α is an empirical constant, determined experimentally to be 4.85. No effect of viscosity on the ratio U/U 0 was observed as the viscosity of the liquid medium was varied from 1x10 -3 to 5x10 -3 Pa.s. The settling velocities of particles in a bimodal mixture were fit by the same correlation; the ratio U/U 0 was independent of the concentrations of different-sized particles

  6. Online Wavelet Complementary velocity Estimator.

    Science.gov (United States)

    Righettini, Paolo; Strada, Roberto; KhademOlama, Ehsan; Valilou, Shirin

    2018-02-01

    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.

  7. Velocity distribution in snow avalanches

    Science.gov (United States)

    Nishimura, K.; Ito, Y.

    1997-12-01

    In order to investigate the detailed structure of snow avalanches, we have made snow flow experiments at the Miyanomori ski jump in Sapporo and systematic observations in the Shiai-dani, Kurobe Canyon. In the winter of 1995-1996, a new device to measure static pressures was used to estimate velocities in the snow cloud that develops above the flowing layer of avalanches. Measurements during a large avalanche in the Shiai-dani which damaged and destroyed some instruments indicate velocities increased rapidly to more than 50 m/s soon after the front. Velocities decreased gradually in the following 10 s. Velocities of the lower flowing layer were also calculated by differencing measurement of impact pressure. Both recordings in the snow cloud and in the flowing layer changed with a similar trend and suggest a close interaction between the two layers. In addition, the velocity showed a periodic change. Power spectrum analysis of the impact pressure and the static pressure depression showed a strong peak at a frequency between 4 and 6 Hz, which might imply the existence of either ordered structure or a series of surges in the flow.

  8. Velocity Estimate Following Air Data System Failure

    National Research Council Canada - National Science Library

    McLaren, Scott A

    2008-01-01

    .... A velocity estimator (VEST) algorithm was developed to combine the inertial and wind velocities to provide an estimate of the aircraft's current true velocity to be used for command path gain scheduling and for display in the cockpit...

  9. Randomization tests

    CERN Document Server

    Edgington, Eugene

    2007-01-01

    Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani

  10. 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....

  11. How required reserve ratio affects distribution and velocity of money

    Science.gov (United States)

    Xi, Ning; Ding, Ning; Wang, Yougui

    2005-11-01

    In this paper the dependence of wealth distribution and the velocity of money on the required reserve ratio is examined based on a random transfer model of money and computer simulations. A fractional reserve banking system is introduced to the model where money creation can be achieved by bank loans and the monetary aggregate is determined by the monetary base and the required reserve ratio. It is shown that monetary wealth follows asymmetric Laplace distribution and latency time of money follows exponential distribution. The expression of monetary wealth distribution and that of the velocity of money in terms of the required reserve ratio are presented in a good agreement with simulation results.

  12. Effect of Core Training on Male Handball Players’ Throwing Velocity

    OpenAIRE

    Manchado, Carmen; García-Ruiz, José; Cortell-Tormo, Juan M.; Tortosa Martínez, Juan

    2017-01-01

    Abstract In handball, throwing velocity is considered to be one of the essential factors in achieving the ultimate aim of scoring a goal. The objective of the present study was to analyze the effect of a core training program on throwing velocity in 30 handball players (age 18.7 ? 3.4 years, body height 179.3 ? 7.0 cm, body mass 78.9 ? 7.7 kg), 16 of whom were in the junior category and 14 of whom were in the senior category. The 30 players were randomly divided into two groups, the control g...

  13. Observation of Resonant Behavior in the Energy Velocity of Diffused Light

    International Nuclear Information System (INIS)

    Sapienza, R.; Garcia, P. D.; Blanco, A.; Lopez, C.; Bertolotti, J.; Wiersma, D. S.; Martin, M. D.; Vina, L.

    2007-01-01

    In this Letter we demonstrate Mie resonances mediated transport of light in randomly arranged, monodisperse dielectric spheres packed at high filling fractions. By means of both static and dynamic optical experiments we show resonant behavior in the key transport parameters and, in particular, we find that the energy transport velocity, which is lower than the group velocity, also displays a resonant behavior

  14. Velocity Loss as a Variable for Monitoring Resistance Exercise.

    Science.gov (United States)

    González-Badillo, Juan José; Yañez-García, Juan Manuel; Mora-Custodio, Ricardo; Rodríguez-Rosell, David

    2017-03-01

    This study aimed to analyze: 1) the pattern of repetition velocity decline during a single set to failure against different submaximal loads (50-85% 1RM) in the bench press exercise; and 2) the reliability of the percentage of performed repetitions, with respect to the maximum possible number that can be completed, when different magnitudes of velocity loss have been reached within each set. Twenty-two men performed 8 tests of maximum number of repetitions (MNR) against loads of 50-55-60-65-70-75-80-85% 1RM, in random order, every 6-7 days. Another 28 men performed 2 separate MNR tests against 60% 1RM. A very close relationship was found between the relative loss of velocity in a set and the percentage of performed repetitions. This relationship was very similar for all loads, but particularly for 50-70% 1RM, even though the number of repetitions completed at each load was significantly different. Moreover, the percentage of performed repetitions for a given velocity loss showed a high absolute reliability. Equations to predict the percentage of performed repetitions from relative velocity loss are provided. By monitoring repetition velocity and using these equations, one can estimate, with considerable precision, how many repetitions are left in reserve in a bench press exercise set. © Georg Thieme Verlag KG Stuttgart · New York.

  15. ROTATIONAL VELOCITIES FOR M DWARFS

    International Nuclear Information System (INIS)

    Jenkins, J. S.; Ramsey, L. W.; Jones, H. R. A.; Pavlenko, Y.; Barnes, J. R.; Pinfield, D. J.; Gallardo, J.

    2009-01-01

    We present spectroscopic rotation velocities (v sin i) for 56 M dwarf stars using high-resolution Hobby-Eberly Telescope High Resolution Spectrograph red spectroscopy. In addition, we have also determined photometric effective temperatures, masses, and metallicities ([Fe/H]) for some stars observed here and in the literature where we could acquire accurate parallax measurements and relevant photometry. We have increased the number of known v sin i values for mid M stars by around 80% and can confirm a weakly increasing rotation velocity with decreasing effective temperature. Our sample of v sin is peak at low velocities (∼3 km s -1 ). We find a change in the rotational velocity distribution between early M and late M stars, which is likely due to the changing field topology between partially and fully convective stars. There is also a possible further change in the rotational distribution toward the late M dwarfs where dust begins to play a role in the stellar atmospheres. We also link v sin i to age and show how it can be used to provide mid-M star age limits. When all literature velocities for M dwarfs are added to our sample, there are 198 with v sin i ≤ 10 km s -1 and 124 in the mid-to-late M star regime (M3.0-M9.5) where measuring precision optical radial velocities is difficult. In addition, we also search the spectra for any significant Hα emission or absorption. Forty three percent were found to exhibit such emission and could represent young, active objects with high levels of radial-velocity noise. We acquired two epochs of spectra for the star GJ1253 spread by almost one month and the Hα profile changed from showing no clear signs of emission, to exhibiting a clear emission peak. Four stars in our sample appear to be low-mass binaries (GJ1080, GJ3129, Gl802, and LHS3080), with both GJ3129 and Gl802 exhibiting double Hα emission features. The tables presented here will aid any future M star planet search target selection to extract stars with low v

  16. How Required Reserve Ratio Affects Distribution and Velocity of Money

    OpenAIRE

    Xi, Ning; Ding, Ning; Wang, Yougui

    2005-01-01

    In this paper the dependence of wealth distribution and the velocity of money on the required reserve ratio is examined based on a random transfer model of money and computer simulations. A fractional reserve banking system is introduced to the model where money creation can be achieved by bank loans and the monetary aggregate is determined by the monetary base and the required reserve ratio. It is shown that monetary wealth follows asymmetric Laplace distribution and latency time of money fo...

  17. Velocity distribution of fragments of catastrophic impacts

    Science.gov (United States)

    Takagi, Yasuhiko; Kato, Manabu; Mizutani, Hitoshi

    1992-01-01

    Three dimensional velocities of fragments produced by laboratory impact experiments were measured for basalts and pyrophyllites. The velocity distribution of fragments obtained shows that the velocity range of the major fragments is rather narrow, at most within a factor of 3 and that no clear dependence of velocity on the fragment mass is observed. The NonDimensional Impact Stress (NDIS) defined by Mizutani et al. (1990) is found to be an appropriate scaling parameter to describe the overall fragment velocity as well as the antipodal velocity.

  18. Random walk on random walks

    NARCIS (Netherlands)

    Hilário, M.; Hollander, den W.Th.F.; Sidoravicius, V.; Soares dos Santos, R.; Teixeira, A.

    2014-01-01

    In this paper we study a random walk in a one-dimensional dynamic random environment consisting of a collection of independent particles performing simple symmetric random walks in a Poisson equilibrium with density ¿¿(0,8). At each step the random walk performs a nearest-neighbour jump, moving to

  19. Electron velocity and momentum density

    International Nuclear Information System (INIS)

    Perkins, G.A.

    1978-01-01

    A null 4-vector eta + sigma/sub μ/based on Dirac's relativistic electron equation, is shown explicitly for a plane wave and various Coulomb states. This 4-vector constitutes a mechanical ''model'' for the electron in those staes, and expresses the important spinor quantities represented conventionally by n, f, g, m, j, kappa, l, and s. The model for a plane wave agrees precisely with the relation between velocity and phase gradient customarily used in quantum theory, but the models for Coulomb states contradict that relation

  20. Instrument for measuring flow velocities

    International Nuclear Information System (INIS)

    Griffo, J.

    1977-01-01

    The design described here means to produce a 'more satisfying instrument with less cost' than comparable instruments known up to now. Instead of one single turbine rotor, two similar ones but with opposite blade inclination and sense of rotation are to be used. A cylindrical measuring body is carrying in its axis two bearing blocks whose shape is offering little flow resistance. On the shaft, supported by them, the two rotors run in opposite direction a relatively small axial distance apart. The speed of each rotor is picked up as pulse recurrence frequency by a transmitter and fed to an electronic measuring unit. Measuring errors as they are caused for single rotors by turbulent flow, profile distortion of the velocity, or viscous flow are to be eliminated by means of the contrarotating turbines and the subsequently added electronic unit, because in these cases the adulterating increase of the angular velocity of one rotor is compensated by a corresponding deceleration of the other rotor. The mean value then indicated by the electronic unit has high accurancy of measurement. (RW) [de

  1. Application of Vectors to Relative Velocity

    Science.gov (United States)

    Tin-Lam, Toh

    2004-01-01

    The topic 'relative velocity' has recently been introduced into the Cambridge Ordinary Level Additional Mathematics syllabus under the application of Vectors. In this note, the results of relative velocity and the 'reduction to rest' technique of teaching relative velocity are derived mathematically from vector algebra, in the hope of providing…

  2. Questions Students Ask: About Terminal Velocity.

    Science.gov (United States)

    Meyer, Earl R.; Nelson, Jim

    1984-01-01

    If a ball were given an initial velocity in excess of its terminal velocity, would the upward force of air resistance (a function of velocity) be greater than the downward force of gravity and thus push the ball back upwards? An answer to this question is provided. (JN)

  3. 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....

  4. Random magnetism

    International Nuclear Information System (INIS)

    Tahir-Kheli, R.A.

    1975-01-01

    A few simple problems relating to random magnetic systems are presented. Translational symmetry, only on the macroscopic scale, is assumed for these systems. A random set of parameters, on the microscopic scale, for the various regions of these systems is also assumed. A probability distribution for randomness is obeyed. Knowledge of the form of these probability distributions, is assumed in all cases [pt

  5. Critical velocities in He II for independently varied superfluid and normal fluid velocities

    International Nuclear Information System (INIS)

    Baehr, M.L.

    1984-01-01

    Experiments were performed to measure the critical velocity in pure superflow and compare to the theoretical prediction; to measure the first critical velocity for independently varied superfluid and normal fluid velocities; and to investigate the propagation of the second critical velocity from the thermal counterflow line through the V/sub n/,-V/sub s/ quadrant. The experimental apparatus employed a thermal counterflow heater to adjust the normal fluid velocity, a fountain pump to vary the superfluid velocity, and a level sensing capacitor to measure the superfluid velocity. The results of the pure superfluid critical velocity measurements indicate that this velocity is temperature independent contrary to Schwarz's theory. It was found that the first critical velocity for independently varied V/sub n/ and V/sub s/ could be described by a linear function of V/sub n/ and was otherwise temperature independent. It was found that the second critical velocity could only be distinguished near the thermal counterflow line

  6. An Approach to Predict Debris Flow Average Velocity

    Directory of Open Access Journals (Sweden)

    Chen Cao

    2017-03-01

    Full Text Available Debris flow is one of the major threats for the sustainability of environmental and social development. The velocity directly determines the impact on the vulnerability. This study focuses on an approach using radial basis function (RBF neural network and gravitational search algorithm (GSA for predicting debris flow velocity. A total of 50 debris flow events were investigated in the Jiangjia gully. These data were used for building the GSA-based RBF approach (GSA-RBF. Eighty percent (40 groups of the measured data were selected randomly as the training database. The other 20% (10 groups of data were used as testing data. Finally, the approach was applied to predict six debris flow gullies velocities in the Wudongde Dam site area, where environmental conditions were similar to the Jiangjia gully. The modified Dongchuan empirical equation and the pulled particle analysis of debris flow (PPA approach were used for comparison and validation. The results showed that: (i the GSA-RBF predicted debris flow velocity values are very close to the measured values, which performs better than those using RBF neural network alone; (ii the GSA-RBF results and the MDEE results are similar in the Jiangjia gully debris flow velocities prediction, and GSA-RBF performs better; (iii in the study area, the GSA-RBF results are validated reliable; and (iv we could consider more variables in predicting the debris flow velocity by using GSA-RBF on the basis of measured data in other areas, which is more applicable. Because the GSA-RBF approach was more accurate, both the numerical simulation and the empirical equation can be taken into consideration for constructing debris flow mitigation works. They could be complementary and verified for each other.

  7. Generation of the auroral electron velocity distribution by electrostatic turbulence

    International Nuclear Information System (INIS)

    Bryant, D.A.; Cook, A.C.; Wang, Z.-S.; Angelis, U. de; Perry, C.H.

    1991-01-01

    It is shown from first principles that the characteristic peak in the auroral electron velocity distribution can be generated stochastically through resonant interactions with lower-hybrid electrostatic turbulence. The peak itself is shown to be the inevitable consequence of restrictions imposed on random walk in velocity space by the limitation in wave group velocity. A Monte-Carlo model of the process demonstrates how the various properties of the acceleration region are reflected in the resultant electron distribution. It is shown, in particular, that the width of the peak is governed by the amplitude of the turbulence, while the amplitude of the peak reflects the column density of wave energy. Electron distributions encountered within three auroral arcs are interpreted to yield order of magnitude estimates of the amplitude and rms electric field of lower-hybrid wave packets. The velocities and frequencies of the resonant waves, the net electric field, the column density of wave energy and the electric field energy density are also estimated. The results are found to be not inconsistent with available electric-field measurements. (author)

  8. Optimal centralized and decentralized velocity feedback control on a beam

    International Nuclear Information System (INIS)

    Engels, W P; Elliott, S J

    2008-01-01

    This paper considers the optimization of a velocity feedback controller with a collocated force actuator, to minimize the kinetic energy of a simply supported beam. If the beam is excited at a single location, the optimum feedback gain varies with the position of the control system. It is shown that this variation depends partly on the location of the control force relative to the exciting force. If a distributed excitation is assumed, that is random in both time and space, a unique optimum value of the feedback gain can be found for a given control location. The effect of the control location on performance and the optimal feedback gain can then be examined and is found to be limited provided the control locations are not close to the ends of the beam. The optimization can also be performed for a multichannel velocity feedback system. Both a centralized and a decentralized controller are considered. It is shown that the difference in performance between a centralized and a decentralized controller is small, unless the control locations are closely spaced. In this case the centralized controller effectively feeds back a moment proportional to angular velocity as well as a force proportional to a velocity. It is also shown that the optimal feedback gain can be approximated on the basis of a limited model and that similar results can be achieved

  9. Randomized random walk on a random walk

    International Nuclear Information System (INIS)

    Lee, P.A.

    1983-06-01

    This paper discusses generalizations of the model introduced by Kehr and Kunter of the random walk of a particle on a one-dimensional chain which in turn has been constructed by a random walk procedure. The superimposed random walk is randomised in time according to the occurrences of a stochastic point process. The probability of finding the particle in a particular position at a certain instant is obtained explicitly in the transform domain. It is found that the asymptotic behaviour for large time of the mean-square displacement of the particle depends critically on the assumed structure of the basic random walk, giving a diffusion-like term for an asymmetric walk or a square root law if the walk is symmetric. Many results are obtained in closed form for the Poisson process case, and these agree with those given previously by Kehr and Kunter. (author)

  10. Linear velocity fields in non-Gaussian models for large-scale structure

    Science.gov (United States)

    Scherrer, Robert J.

    1992-01-01

    Linear velocity fields in two types of physically motivated non-Gaussian models are examined for large-scale structure: seed models, in which the density field is a convolution of a density profile with a distribution of points, and local non-Gaussian fields, derived from a local nonlinear transformation on a Gaussian field. The distribution of a single component of the velocity is derived for seed models with randomly distributed seeds, and these results are applied to the seeded hot dark matter model and the global texture model with cold dark matter. An expression for the distribution of a single component of the velocity in arbitrary local non-Gaussian models is given, and these results are applied to such fields with chi-squared and lognormal distributions. It is shown that all seed models with randomly distributed seeds and all local non-Guassian models have single-component velocity distributions with positive kurtosis.

  11. The role of topography and lateral velocity heterogeneities on near-source scattering and ground-motion variability

    KAUST Repository

    Imperatori, W.; Mai, Paul Martin

    2015-01-01

    The scattering of seismic waves travelling in the Earth is not only caused by random velocity heterogeneity but also by surface topography. Both factors are known to strongly affect ground-motion complexity even at relatively short distance from

  12. Determination of velocity correction factors for real-time air velocity monitoring in underground mines

    OpenAIRE

    Zhou, Lihong; Yuan, Liming; Thomas, Rick; Iannacchione, Anthony

    2017-01-01

    When there are installations of air velocity sensors in the mining industry for real-time airflow monitoring, a problem exists with how the monitored air velocity at a fixed location corresponds to the average air velocity, which is used to determine the volume flow rate of air in an entry with the cross-sectional area. Correction factors have been practically employed to convert a measured centerline air velocity to the average air velocity. However, studies on the recommended correction fac...

  13. Short-term effects of a standardized glucose load on region-specific aortic pulse wave velocity assessed by MRI

    NARCIS (Netherlands)

    Jonker, J.T.; Tjeerdema, N.; Hensen, L.C.; Lamb, H.J.; Romijn, J.A.; Smit, J.W.; Westenberg, J.J.; Roos, A. de

    2014-01-01

    PURPOSE: To assess the short-term effects of a standardized oral glucose load on regional aortic pulse wave velocity (PWV) using two-directional in-plane velocity encoded MRI. MATERIALS AND METHODS: A randomized, controlled intervention was performed in 16 male subjects (mean +/- standard deviation:

  14. Characteristic wave velocities in spherical electromagnetic cloaks

    International Nuclear Information System (INIS)

    Yaghjian, A D; Maci, S; Martini, E

    2009-01-01

    We investigate the characteristic wave velocities in spherical electromagnetic cloaks, namely, phase, ray, group and energy-transport velocities. After deriving explicit expressions for the phase and ray velocities (the latter defined as the phase velocity along the direction of the Poynting vector), special attention is given to the determination of group and energy-transport velocities, because a cursory application of conventional formulae for local group and energy-transport velocities can lead to a discrepancy between these velocities if the permittivity and permeability dyadics are not equal over a frequency range about the center frequency. In contrast, a general theorem can be proven from Maxwell's equations that the local group and energy-transport velocities are equal in linear, lossless, frequency dispersive, source-free bianisotropic material. This apparent paradox is explained by showing that the local fields of the spherical cloak uncouple into an E wave and an H wave, each with its own group and energy-transport velocities, and that the group and energy-transport velocities of either the E wave or the H wave are equal and thus satisfy the general theorem.

  15. Geotail observations of FTE velocities

    Directory of Open Access Journals (Sweden)

    G. I. Korotova

    2009-01-01

    Full Text Available We discuss the plasma velocity signatures expected in association with flux transfer events (FTEs. Events moving faster than or opposite the ambient media should generate bipolar inward/outward (outward/inward flow perturbations normal to the nominal magnetopause in the magnetosphere (magnetosheath. Flow perturbations directly upstream and downstream from the events should be in the direction of event motion. Flows on the flanks should be in the direction opposite the motion of events moving at subsonic and subAlfvénic speeds relative to the ambient plasma. Events moving with the ambient flow should generate no flow perturbations in the ambient plasma. Alfvén waves propagating parallel (antiparallel to the axial magnetic field of FTEs may generate anticorrelated (correlated magnetic field and flow perturbations within the core region of FTEs. We present case studies illustrating many of these signatures. In the examples considered, Alfvén waves propagate along event axes away from the inferred reconnection site. A statistical study of FTEs observed by Geotail over a 3.5-year period reveals that FTEs within the magnetosphere invariably move faster than the ambient flow, while those in the magnetosheath move both faster and slower than the ambient flow.

  16. Reciprocally-Rotating Velocity Obstacles

    KAUST Repository

    Giese, Andrew

    2014-05-01

    © 2014 IEEE. Modern multi-agent systems frequently use highlevel planners to extract basic paths for agents, and then rely on local collision avoidance to ensure that the agents reach their destinations without colliding with one another or dynamic obstacles. One state-of-the-art local collision avoidance technique is Optimal Reciprocal Collision Avoidance (ORCA). Despite being fast and efficient for circular-shaped agents, ORCA may deadlock when polygonal shapes are used. To address this shortcoming, we introduce Reciprocally-Rotating Velocity Obstacles (RRVO). RRVO generalizes ORCA by introducing a notion of rotation for polygonally-shaped agents. This generalization permits more realistic motion than ORCA and does not suffer from as much deadlock. In this paper, we present the theory of RRVO and show empirically that it does not suffer from the deadlock issue ORCA has, permits agents to reach goals faster, and has a comparable collision rate at the cost of performance overhead quadratic in the (typically small) user-defined parameter δ.

  17. High velocity impact experiment (HVIE)

    Energy Technology Data Exchange (ETDEWEB)

    Toor, A.; Donich, T.; Carter, P.

    1998-02-01

    The HVIE space project was conceived as a way to measure the absolute EOS for approximately 10 materials at pressures up to {approximately}30 Mb with order-of-magnitude higher accuracy than obtainable in any comparable experiment conducted on earth. The experiment configuration is such that each of the 10 materials interacts with all of the others thereby producing one-hundred independent, simultaneous EOS experiments The materials will be selected to provide critical information to weapons designers, National Ignition Facility target designers and planetary and geophysical scientists. In addition, HVIE will provide important scientific information to other communities, including the Ballistic Missile Defense Organization and the lethality and vulnerability community. The basic HVIE concept is to place two probes in counter rotating, highly elliptical orbits and collide them at high velocity (20 km/s) at 100 km altitude above the earth. The low altitude of the experiment will provide quick debris strip-out of orbit due to atmospheric drag. The preliminary conceptual evaluation of the HVIE has found no show stoppers. The design has been very easy to keep within the lift capabilities of commonly available rides to low earth orbit including the space shuttle. The cost of approximately 69 million dollars for 100 EOS experiment that will yield the much needed high accuracy, absolute measurement data is a bargain!

  18. Group Velocity for Leaky Waves

    Science.gov (United States)

    Rzeznik, Andrew; Chumakova, Lyubov; Rosales, Rodolfo

    2017-11-01

    In many linear dispersive/conservative wave problems one considers solutions in an infinite medium which is uniform everywhere except for a bounded region. In general, localized inhomogeneities of the medium cause partial internal reflection, and some waves leak out of the domain. Often one only desires the solution in the inhomogeneous region, with the exterior accounted for by radiation boundary conditions. Formulating such conditions requires definition of the direction of energy propagation for leaky waves in multiple dimensions. In uniform media such waves have the form exp (d . x + st) where d and s are complex and related by a dispersion relation. A complex s is required since these waves decay via radiation to infinity, even though the medium is conservative. We present a modified form of Whitham's Averaged Lagrangian Theory along with modulation theory to extend the classical idea of group velocity to leaky waves. This allows for solving on the bounded region by representing the waves as a linear combination of leaky modes, each exponentially decaying in time. This presentation is part of a joint project, and applications of these results to example GFD problems will be presented by L. Chumakova in the talk ``Leaky GFD Problems''. This work is partially supported by NSF Grants DMS-1614043, DMS-1719637, and 1122374, and by the Hertz Foundation.

  19. Intermittent Lagrangian velocities and accelerations in three-dimensional porous medium flow.

    Science.gov (United States)

    Holzner, M; Morales, V L; Willmann, M; Dentz, M

    2015-07-01

    Intermittency of Lagrangian velocity and acceleration is a key to understanding transport in complex systems ranging from fluid turbulence to flow in porous media. High-resolution optical particle tracking in a three-dimensional (3D) porous medium provides detailed 3D information on Lagrangian velocities and accelerations. We find sharp transitions close to pore throats, and low flow variability in the pore bodies, which gives rise to stretched exponential Lagrangian velocity and acceleration distributions characterized by a sharp peak at low velocity, superlinear evolution of particle dispersion, and double-peak behavior in the propagators. The velocity distribution is quantified in terms of pore geometry and flow connectivity, which forms the basis for a continuous-time random-walk model that sheds light on the observed Lagrangian flow and transport behaviors.

  20. 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

  1. Resonant coherent ionization in grazing ion/atom-surface collisions at high velocities

    Energy Technology Data Exchange (ETDEWEB)

    Garcia de Abajo, F J [Dept. de Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, Univ. del Pais Vasco, San Sebastian (Spain); Pitarke, J M [Materia Kondentsatuaren Fisika Saila, Zientzi Fakultatea, Euskal Herriko Univ., Bilbo (Spain)

    1994-05-01

    The resonant coherent interaction of a fast ion/atom with an oriented crystal surface under grazing incidence conditions is shown to contribute significantly to ionize the probe for high enough velocities and motion along a random direction. The dependence of this process on both the distance to the surface and the velocity of the projectile is studied in detail. We focus on the case of hydrogen moving with a velocity above 2 a.u. Comparison with other mechanisms of charge transfer, such as capture from inner shells of the target atoms, permits us to draw some conclusions about the charge state of the outgoing projectiles. (orig.)

  2. Mathematical model for logarithmic scaling of velocity fluctuations in wall turbulence.

    Science.gov (United States)

    Mouri, Hideaki

    2015-12-01

    For wall turbulence, moments of velocity fluctuations are known to be logarithmic functions of the height from the wall. This logarithmic scaling is due to the existence of a characteristic velocity and to the nonexistence of any characteristic height in the range of the scaling. By using the mathematics of random variables, we obtain its necessary and sufficient conditions. They are compared with characteristics of a phenomenological model of eddies attached to the wall and also with those of the logarithmic scaling of the mean velocity.

  3. Resonant coherent ionization in grazing ion/atom-surface collisions at high velocities

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Pitarke, J.M.

    1994-01-01

    The resonant coherent interaction of a fast ion/atom with an oriented crystal surface under grazing incidence conditions is shown to contribute significantly to ionize the probe for high enough velocities and motion along a random direction. The dependence of this process on both the distance to the surface and the velocity of the projectile is studied in detail. We focus on the case of hydrogen moving with a velocity above 2 a.u. Comparison with other mechanisms of charge transfer, such as capture from inner shells of the target atoms, permits us to draw some conclusions about the charge state of the outgoing projectiles. (orig.)

  4. 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...... search can also yield the direction, and the full velocity vector is thereby found. An examples from a flow rig is shown....

  5. Algorithms for estimating blood velocities using ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2000-01-01

    Ultrasound has been used intensively for the last 15 years for studying the hemodynamics of the human body. Systems for determining both the velocity distribution at one point of interest (spectral systems) and for displaying a map of velocity in real time have been constructed. A number of schemes...... have been developed for performing the estimation, and the various approaches are described. The current systems only display the velocity along the ultrasound beam direction and a velocity transverse to the beam is not detected. This is a major problem in these systems, since most blood vessels...... are parallel to the skin surface. Angling the transducer will often disturb the flow, and new techniques for finding transverse velocities are needed. The various approaches for determining transverse velocities will be explained. This includes techniques using two-dimensional correlation (speckle tracking...

  6. The Acute Effects of Upper Extremity Stretching on Throwing Velocity in Baseball Throwers

    Directory of Open Access Journals (Sweden)

    Michael Williams

    2013-01-01

    Full Text Available Purpose. To examine the effects of static and proprioceptive neuromuscular facilitation (PNF stretching of the shoulder internal rotators on throwing velocity. Subjects. 27 male throwers (mean age = 25.1 years old, SD = 2.4 with adequate knowledge of demonstrable throwing mechanics. Study Design. Randomized crossover trial with repeated measures. Methods. Subjects warmed up, threw 10 pitches at their maximum velocity, were randomly assigned to 1 of 3 stretching protocols (static, PNF, or no stretch, and then repeated their 10 pitches. Velocities were recorded after each pitch and average and peak velocities were recorded after each session. Results. Data were analyzed using a repeated measures ANOVA. No significant interaction between stretching and throwing velocity was observed. Main effects for time were not statistically significant. Main effects for the stretching groups were statistically significant. Discussion. Results suggest that stretching of the shoulder internal rotators did not significantly affect throwing velocity immediately after stretching. This may be due to the complexity of the throwing task. Conclusions. Stretching may be included in a thrower's warm-up without any effects on throwing velocity. Further research should be performed using a population with more throwing experience and skill.

  7. Effect of Core Training on Male Handball Players' Throwing Velocity.

    Science.gov (United States)

    Manchado, Carmen; García-Ruiz, José; Cortell-Tormo, Juan Manuel; Tortosa-Martínez, Juan

    2017-02-01

    In handball, throwing velocity is considered to be one of the essential factors in achieving the ultimate aim of scoring a goal. The objective of the present study was to analyze the effect of a core training program on throwing velocity in 30 handball players (age 18.7 ± 3.4 years, body height 179.3 ± 7.0 cm, body mass 78.9 ± 7.7 kg), 16 of whom were in the junior category and 14 of whom were in the senior category. The 30 players were randomly divided into two groups, the control group (n = 15) and the experimental group (n = 15). For a period of ten weeks, both groups attended their regular handball training sessions (four per week), but in addition, the experimental group participated in a program specifically aimed at progressively strengthening the lumbo-pelvic region and consisting of seven exercises performed after the general warm-up in each regular session. Pre- and post-tests were carried out to analyze each player's throwing velocity from different throwing positions and thus assess the effects of this specific training program. Statistically significant differences (p ≤ 0.05) in throwing velocity were observed between the experimental group, which presented a percentage improvement of 4.5%, and the control group, which did not show any improvement. The results seem to indicate that an increase in the strength and stability of the lumbo-pelvic region can contribute to an improvement in the kinetic chain of the specific movement of throwing in handball, thus, increasing throwing velocity.

  8. Effect of Core Training on Male Handball Players’ Throwing Velocity

    Science.gov (United States)

    García-Ruiz, José; Cortell-Tormo, Juan Manuel; Tortosa-Martínez, Juan

    2017-01-01

    Abstract In handball, throwing velocity is considered to be one of the essential factors in achieving the ultimate aim of scoring a goal. The objective of the present study was to analyze the effect of a core training program on throwing velocity in 30 handball players (age 18.7 ± 3.4 years, body height 179.3 ± 7.0 cm, body mass 78.9 ± 7.7 kg), 16 of whom were in the junior category and 14 of whom were in the senior category. The 30 players were randomly divided into two groups, the control group (n = 15) and the experimental group (n = 15). For a period of ten weeks, both groups attended their regular handball training sessions (four per week), but in addition, the experimental group participated in a program specifically aimed at progressively strengthening the lumbo-pelvic region and consisting of seven exercises performed after the general warm-up in each regular session. Pre- and post-tests were carried out to analyze each player’s throwing velocity from different throwing positions and thus assess the effects of this specific training program. Statistically significant differences (p ≤ 0.05) in throwing velocity were observed between the experimental group, which presented a percentage improvement of 4.5%, and the control group, which did not show any improvement. The results seem to indicate that an increase in the strength and stability of the lumbo-pelvic region can contribute to an improvement in the kinetic chain of the specific movement of throwing in handball, thus, increasing throwing velocity. PMID:28469756

  9. Remote determination of the velocity index and mean streamwise velocity profiles

    Science.gov (United States)

    Johnson, E. D.; Cowen, E. A.

    2017-09-01

    When determining volumetric discharge from surface measurements of currents in a river or open channel, the velocity index is typically used to convert surface velocities to depth-averaged velocities. The velocity index is given by, k=Ub/Usurf, where Ub is the depth-averaged velocity and Usurf is the local surface velocity. The USGS (United States Geological Survey) standard value for this coefficient, k = 0.85, was determined from a series of laboratory experiments and has been widely used in the field and in laboratory measurements of volumetric discharge despite evidence that the velocity index is site-specific. Numerous studies have documented that the velocity index varies with Reynolds number, flow depth, and relative bed roughness and with the presence of secondary flows. A remote method of determining depth-averaged velocity and hence the velocity index is developed here. The technique leverages the findings of Johnson and Cowen (2017) and permits remote determination of the velocity power-law exponent thereby, enabling remote prediction of the vertical structure of the mean streamwise velocity, the depth-averaged velocity, and the velocity index.

  10. Middle cerebral artery blood velocity during running

    DEFF Research Database (Denmark)

    Lyngeraa, Tobias; Pedersen, Lars Møller; Mantoni, T

    2013-01-01

    for eight subjects, respectively, were excluded from analysis because of insufficient signal quality. Running increased mean arterial pressure and mean MCA velocity and induced rhythmic oscillations in BP and in MCA velocity corresponding to the difference between step rate and heart rate (HR) frequencies....... During running, rhythmic oscillations in arterial BP induced by interference between HR and step frequency impact on cerebral blood velocity. For the exercise as a whole, average MCA velocity becomes elevated. These results suggest that running not only induces an increase in regional cerebral blood flow...

  11. Demonstration of a Vector Velocity Technique

    DEFF Research Database (Denmark)

    Hansen, Peter Møller; Pedersen, Mads M.; Hansen, Kristoffer L.

    2011-01-01

    With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60–70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa......With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60–70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner...

  12. On whistler-mode group velocity

    International Nuclear Information System (INIS)

    Sazhin, S.S.

    1986-01-01

    An analytical of the group velocity of whistler-mode waves propagating parallel to the magnetic field in a hot anisotropic plasma is presented. Some simple approximate formulae, which can be used for the magnetospheric applications, are derived. These formulae can predict some properties of this group velocity which were not previously recognized or were obtained by numerical methods. In particular, it is pointed out that the anisotropy tends to compensate for the influence of the electron temperature on the value of the group velocity when the wave frequency is well below the electron gyrofrequency. It is predicted, that under conditions at frequencies near the electron gyrofrequency, this velocity tends towards zero

  13. Velocity measurement of conductor using electromagnetic induction

    International Nuclear Information System (INIS)

    Kim, Gu Hwa; Kim, Ho Young; Park, Joon Po; Jeong, Hee Tae; Lee, Eui Wan

    2002-01-01

    A basic technology was investigated to measure the speed of conductor by non-contact electromagnetic method. The principle of the velocity sensor was electromagnetic induction. To design electromagnet for velocity sensor, 2D electromagnetic analysis was performed using FEM software. The sensor output was analyzed according to the parameters of velocity sensor, such as the type of magnetizing currents and the lift-off. Output of magnetic sensor was linearly depended on the conductor speed and magnetizing current. To compensate the lift-off changes during measurement of velocity, the other magnetic sensor was put at the pole of electromagnet.

  14. 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.

  15. Random Fields

    Science.gov (United States)

    Vanmarcke, Erik

    1983-03-01

    Random variation over space and time is one of the few attributes that might safely be predicted as characterizing almost any given complex system. Random fields or "distributed disorder systems" confront astronomers, physicists, geologists, meteorologists, biologists, and other natural scientists. They appear in the artifacts developed by electrical, mechanical, civil, and other engineers. They even underlie the processes of social and economic change. The purpose of this book is to bring together existing and new methodologies of random field theory and indicate how they can be applied to these diverse areas where a "deterministic treatment is inefficient and conventional statistics insufficient." Many new results and methods are included. After outlining the extent and characteristics of the random field approach, the book reviews the classical theory of multidimensional random processes and introduces basic probability concepts and methods in the random field context. It next gives a concise amount of the second-order analysis of homogeneous random fields, in both the space-time domain and the wave number-frequency domain. This is followed by a chapter on spectral moments and related measures of disorder and on level excursions and extremes of Gaussian and related random fields. After developing a new framework of analysis based on local averages of one-, two-, and n-dimensional processes, the book concludes with a chapter discussing ramifications in the important areas of estimation, prediction, and control. The mathematical prerequisite has been held to basic college-level calculus.

  16. Variational treatment of the centre-of-mass motion

    International Nuclear Information System (INIS)

    Cornelissens, T.

    1986-01-01

    The weightfunction in Lipkin's general expression for eliminating the centre-of-mass coordinate from nuclear wavefunctions has been approximated by a gaussian function exp (-lambdaR 2 ) with one parameter lambda to be determined by a variational calculation. This variational calculation has been carried out for the ground state of 6 Li, first using a wavefunction with different oscillator parameters for the s and p nucleons, second using oscillator functions which are also axially deformed. In both cases the centre-of-mass treatment leads to a remarkable energy gain. The lowest energies are obtained for a negative value of lambda. This surprising result can be explained on the basis of a cluster model for the internal wavefunction of 6 Li : the negative value of lambda increases the separation between the alpha and deuteron cluster. As a further test for our centre-of-mass corrected internal wavefunctions we have calculated the charge formfactor of 6 Li. At low momentum transfer we obtain an excellent agreement with the experimental results. At higher momentum transfers we obtain a diffraction dip, but not yet at the right position and height. Finally we have compared our results for the ground state energy with different cluster model results in the literature. We can conclude that, even without using a generator coordinate method, our centre-of-mass corrected wavefunctions lead to equally good results as the most sophisticated cluster models

  17. Kinematics of the entire East African Rift from GPS velocities

    Science.gov (United States)

    Floyd, M.; King, R. W.

    2017-12-01

    Through a collaborative effort of the GeoPRISMS East Africa Rift GPS Working Group, we have collected and collated all of the publicly available continuous and survey-mode data for the entire rift system between 1994 and 2017 and processed these data as part of a larger velocity solution for Africa, Arabia and western Eurasia. We present here our velocity solution encompassing the major bounding plates and intervening terranes along the East African Rift from the Red Sea to the Malawi Rift and adjacent regions for GPS sites with data spans of at least 2.4 years, and north and east velocity uncertainties less than 1.5 mm/yr. To obtain realistic uncertainties for the velocity estimates, we attempted at each stage of the analysis to account for the character of the noise: During phase processing, we used an elevation-dependent weighting based on the phase residuals for each station; we then examined each position time series, removing outliers and reweighting appropriately to account for the white noise component of the errors; and e accounted for temporal correlations by estimating an equivalent random-walk magnitude for each continuous site and applying the median value (0.5 mm/√yr) to all survey-mode sites. We rigorously estimate relative rotation rates of Nubia, by choosing subset of well-determined sites such that the effective weights of western, northeastern and southern Africa were roughly equivalent, and Somalia, for which the estimate is dominated by three sites (MALI, RCMN, SEY1) whose uncertainties are a factor of 2-3 smaller than those of the other sites. For both plates, the weighted root-mean-square of the velocity residuals is 0.5 mm/yr. Our unified velocity solution provides a geodetic framework and constraints on the continental-scale kinematics of surface motions as well as more local effects both within and outside of the rift structures. Specific focus areas with denser coverage than previous fields include the Danakil block, the Afar Rift, the

  18. Distributed Velocity-Dependent Protocol for Multihop Cellular Sensor Networks

    Directory of Open Access Journals (Sweden)

    Deepthi Chander

    2009-01-01

    Full Text Available Cell phones are embedded with sensors form a Cellular Sensor Network which can be used to localize a moving event. The inherent mobility of the application and of the cell phone users warrants distributed structure-free data aggregation and on-the-fly routing. We propose a Distributed Velocity-Dependent (DVD protocol to localize a moving event using a Multihop Cellular Sensor Network (MCSN. DVD is based on a novel form of connectivity determined by the waiting time of nodes for a Random Waypoint (RWP distribution of cell phone users. This paper analyzes the time-stationary and spatial distribution of the proposed waiting time to explain the superior event localization and delay performances of DVD over the existing Randomized Waiting (RW protocol. A sensitivity analysis is also performed to compare the performance of DVD with RW and the existing Centralized approach.

  19. Distributed Velocity-Dependent Protocol for Multihop Cellular Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jagyasi Bhushan

    2009-01-01

    Full Text Available Abstract Cell phones are embedded with sensors form a Cellular Sensor Network which can be used to localize a moving event. The inherent mobility of the application and of the cell phone users warrants distributed structure-free data aggregation and on-the-fly routing. We propose a Distributed Velocity-Dependent (DVD protocol to localize a moving event using a Multihop Cellular Sensor Network (MCSN. DVD is based on a novel form of connectivity determined by the waiting time of nodes for a Random Waypoint (RWP distribution of cell phone users. This paper analyzes the time-stationary and spatial distribution of the proposed waiting time to explain the superior event localization and delay performances of DVD over the existing Randomized Waiting (RW protocol. A sensitivity analysis is also performed to compare the performance of DVD with RW and the existing Centralized approach.

  20. Velocity spectrum for the Iranian plateau

    Science.gov (United States)

    Bastami, Morteza; Soghrat, M. R.

    2018-01-01

    Peak ground acceleration (PGA) and spectral acceleration values have been proposed in most building codes/guidelines, unlike spectral velocity (SV) and peak ground velocity (PGV). Recent studies have demonstrated the importance of spectral velocity and peak ground velocity in the design of long period structures (e.g., pipelines, tunnels, tanks, and high-rise buildings) and evaluation of seismic vulnerability in underground structures. The current study was undertaken to develop a velocity spectrum and for estimation of PGV. In order to determine these parameters, 398 three-component accelerograms recorded by the Building and Housing Research Center (BHRC) were used. The moment magnitude (Mw) in the selected database was 4.1 to 7.3, and the events occurred after 1977. In the database, the average shear-wave velocity at 0 to 30 m in depth (Vs30) was available for only 217 records; thus, the site class for the remaining was estimated using empirical methods. Because of the importance of the velocity spectrum at low frequencies, the signal-to-noise ratio of 2 was chosen for determination of the low and high frequency to include a wider range of frequency content. This value can produce conservative results. After estimation of the shape of the velocity design spectrum, the PGV was also estimated for the region under study by finding the correlation between PGV and spectral acceleration at the period of 1 s.

  1. Analyses of hydraulic performance of velocity caps

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Degn Eskesen, Mark Chr.; Buhrkall, Jeppe

    2014-01-01

    The hydraulic performance of a velocity cap has been investigated. Velocity caps are often used in connection with offshore intakes. CFD (computational fluid dynamics) examined the flow through the cap openings and further down into the intake pipes. This was combined with dimension analyses...

  2. Photoelectric Radial Velocities, Paper XIX Additional Spectroscopic ...

    Indian Academy of Sciences (India)

    ian velocity curve that does justice to the measurements, but it cannot be expected to have much predictive power. Key words. Stars: late-type—stars: radial velocities—spectroscopic binaries—orbits. 0. Preamble. The 'Redman K stars' are a lot of seventh-magnitude K stars whose radial velocities were first observed by ...

  3. Crack velocity measurement by induced electromagnetic radiation

    International Nuclear Information System (INIS)

    Frid, V.; Rabinovitch, A.; Bahat, D.

    2006-01-01

    Our model of electromagnetic radiation (EMR) emanated from fracture implies that EMR amplitude is proportional to crack velocity. Soda lime glass samples were tested under uniaxial tension. Comparison of crack velocity observed by Wallner line analysis and the peak amplitude of EMR signals registered during the test, showed very good correlation, validating this proportionality

  4. Crack velocity measurement by induced electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Frid, V. [Deichmann Rock Mechanics Laboratory of the Negev, Geological and Environmental Sciences Department, Ben Gurion University of the Negev, Beer Sheva (Israel)]. E-mail: vfrid@bgu.ac.il; Rabinovitch, A. [Deichmann Rock Mechanics Laboratory of the Negev, Physics Department, Ben Gurion University of the Negev, Beer Sheva (Israel); Bahat, D. [Deichmann Rock Mechanics Laboratory of the Negev, Geological and Environmental Sciences Department, Ben Gurion University of the Negev, Beer Sheva (Israel)

    2006-07-31

    Our model of electromagnetic radiation (EMR) emanated from fracture implies that EMR amplitude is proportional to crack velocity. Soda lime glass samples were tested under uniaxial tension. Comparison of crack velocity observed by Wallner line analysis and the peak amplitude of EMR signals registered during the test, showed very good correlation, validating this proportionality.

  5. Estimation of blood velocities using ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    imaging, and, finally, some of the more recent experimental techniques. The authors shows that the Doppler shift, usually considered the way velocity is detected, actually, plays a minor role in pulsed systems. Rather, it is the shift of position of signals between pulses that is used in velocity...

  6. Peculiar velocity measurement in a clumpy universe

    Science.gov (United States)

    Habibi, Farhang; Baghram, Shant; Tavasoli, Saeed

    Aims: In this work, we address the issue of peculiar velocity measurement in a perturbed Friedmann universe using the deviations from measured luminosity distances of standard candles from background FRW universe. We want to show and quantify the statement that in intermediate redshifts (0.5 deviations from the background FRW model are not uniquely governed by peculiar velocities. Luminosity distances are modified by gravitational lensing. We also want to indicate the importance of relativistic calculations for peculiar velocity measurement at all redshifts. Methods: For this task, we discuss the relativistic correction on luminosity distance and redshift measurement and show the contribution of each of the corrections as lensing term, peculiar velocity of the source and Sachs-Wolfe effect. Then, we use the SNe Ia sample of Union 2, to investigate the relativistic effects, we consider. Results: We show that, using the conventional peculiar velocity method, that ignores the lensing effect, will result in an overestimate of the measured peculiar velocities at intermediate redshifts. Here, we quantify this effect. We show that at low redshifts the lensing effect is negligible compare to the effect of peculiar velocity. From the observational point of view, we show that the uncertainties on luminosity of the present SNe Ia data prevent us from precise measuring the peculiar velocities even at low redshifts (z < 0.2).

  7. Radial velocities of RR Lyrae stars

    International Nuclear Information System (INIS)

    Hawley, S.L.; Barnes, T.G. III

    1985-01-01

    283 spectra of 57 RR Lyrae stars have been obtained using the 2.1-m telescope at McDonald Observatory. Radial velocities were determined using a software cross-correlation technique. New mean radial velocities were determined for 46 of the stars. 11 references

  8. The measurement of low air flow velocities

    NARCIS (Netherlands)

    Aghaei, A.; Mao, X.G.; Zanden, van der A.J.J.; Schaik, W.H.J.; Hendriks, N.A.

    2005-01-01

    Air flow velocity is measured with an acoustic sensor, which can be used especially for measuring low air flow velocities as well as the temperature of the air simultaneously. Two opposite transducers send a sound pulse towards each other. From the difference of the transit times, the air flow

  9. Critical Landau Velocity in Helium Nanodroplets

    NARCIS (Netherlands)

    Brauer, N.B.; Smolarek, S.; Loginov, E.; Mateo, D.; Hernando, A.; Pi, M.; Barranco, M.; Buma, W.J.; Drabbels, M.

    2013-01-01

    The best-known property of superfluid helium is the vanishing viscosity that objects experience while moving through the liquid with speeds below the so-called critical Landau velocity. This critical velocity is generally considered a macroscopic property as it is related to the collective

  10. Comparison of high group velocity accelerating structures

    International Nuclear Information System (INIS)

    Farkas, Z.D.; Wilson, P.B.

    1987-02-01

    It is well known that waveguides with no perturbations have phase velocities greater than the velocity of light c. If the waveguide dimensions are chosen so that the phase velocity is only moderately greater than c, only small perturbations are required to reduce the phase velocity to be synchronous with a high energy particle bunch. Such a lightly loaded accelerator structure will have smaller longitudinal and transverse wake potentials and hence will lead to lower emittance growth in an accelerated beam. Since these structures are lightly loaded, their group velocities are only slightly less than c and not in the order of 0.01c, as is the case for the standard disk-loaded structures. To ascertain that the peak and average power requirements for these structures are not prohibitive, we examine the elastance and the Q for several traveling wave structures: phase slip structures, bellows-like structures, and lightly loaded disk-loaded structures

  11. Detonation velocity in poorly mixed gas mixtures

    Science.gov (United States)

    Prokhorov, E. S.

    2017-10-01

    The technique for computation of the average velocity of plane detonation wave front in poorly mixed mixture of gaseous hydrocarbon fuel and oxygen is proposed. Here it is assumed that along the direction of detonation propagation the chemical composition of the mixture has periodic fluctuations caused, for example, by layered stratification of gas charge. The technique is based on the analysis of functional dependence of ideal (Chapman-Jouget) detonation velocity on mole fraction (with respect to molar concentration) of the fuel. It is shown that the average velocity of detonation can be significantly (by more than 10%) less than the velocity of ideal detonation. The dependence that permits to estimate the degree of mixing of gas mixture basing on the measurements of average detonation velocity is established.

  12. A glance at velocity structure of Izmir

    Energy Technology Data Exchange (ETDEWEB)

    Özer, Çağlar, E-mail: caglar.ozer@deu.edu.tr [Dokuz Eylul University, Faculty of Engineering, Geophysical Engineering Department, Izmir (Turkey); Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Department of Geophysical Engineering, Izmir (Turkey); Polat, Orhan, E-mail: orhan.polat@deu.edu.tr [Dokuz Eylul University, Faculty of Engineering, Geophysical Engineering Department, Izmir (Turkey)

    2016-04-18

    In this study; we investigated velocity structure of Izmir and surroundings. We used local earthquake data which was recorded by different type of instruments and obtained high resolution 3D sections. We selected more than 400 earthquakes which were occurred between 2010 and 2013. Examined tomographic sections especially in Izmir along coastal areas (Mavisehir-Inciraltı); revealed the low speed zone. Along this low-speed zone; it is consistent with the results obtained from the stratigraphic section and surface geology. While; low velocity zones are associated with faults and water content; high velocity is related to magmatic rocks or compact rocks. Along Karsıyaka, Seferihisar, Orhanlı, Izmir fault zones; low P velocity was observed. When examined higher elevations of the topography; which are composed of soured magmatic material is dominated by high P velocity. In all horizontal sections; resolution decreasing with increasing depth. The reason for this; the reduction of earthquakes causes ray tracing problems.

  13. The Effect of Velocity Correlation on the Spatial Evolution of Breakthrough Curves in Heterogeneous Media

    Science.gov (United States)

    Massoudieh, A.; Dentz, M.; Le Borgne, T.

    2017-12-01

    In heterogeneous media, the velocity distribution and the spatial correlation structure of velocity for solute particles determine the breakthrough curves and how they evolve as one moves away from the solute source. The ability to predict such evolution can help relating the spatio-statistical hydraulic properties of the media to the transport behavior and travel time distributions. While commonly used non-local transport models such as anomalous dispersion and classical continuous time random walk (CTRW) can reproduce breakthrough curve successfully by adjusting the model parameter values, they lack the ability to relate model parameters to the spatio-statistical properties of the media. This in turns limits the transferability of these models. In the research to be presented, we express concentration or flux of solutes as a distribution over their velocity. We then derive an integrodifferential equation that governs the evolution of the particle distribution over velocity at given times and locations for a particle ensemble, based on a presumed velocity correlation structure and an ergodic cross-sectional velocity distribution. This way, the spatial evolution of breakthrough curves away from the source is predicted based on cross-sectional velocity distribution and the connectivity, which is expressed by the velocity transition probability density. The transition probability is specified via a copula function that can help construct a joint distribution with a given correlation and given marginal velocities. Using this approach, we analyze the breakthrough curves depending on the velocity distribution and correlation properties. The model shows how the solute transport behavior evolves from ballistic transport at small spatial scales to Fickian dispersion at large length scales relative to the velocity correlation length.

  14. Scaling properties of conduction velocity in heterogeneous excitable media

    Science.gov (United States)

    Shajahan, T. K.; Borek, Bartłomiej; Shrier, Alvin; Glass, Leon

    2011-10-01

    Waves of excitation through excitable media, such as cardiac tissue, can propagate as plane waves or break up to form reentrant spiral waves. In diseased hearts reentrant waves can be associated with fatal cardiac arrhythmias. In this paper we investigate the conditions that lead to wave break, reentry, and propagation failure in mathematical models of heterogeneous excitable media. Two types of heterogeneities are considered: sinks are regions in space in which the voltage is fixed at its rest value, and breaks are nonconducting regions with no-flux boundary conditions. We find that randomly distributed heterogeneities in the medium have a decremental effect on the velocity, and above a critical density of such heterogeneities the conduction fails. Using numerical and analytical methods we derive the general relationship among the conduction velocity, density of heterogeneities, diffusion coefficient, and the rise time of the excitation in both two and three dimensions. This work helps us understand the factors leading to reduced propagation velocity and the formation of spiral waves in heterogeneous excitable media.

  15. Influence of lateral slab edge distance on plate velocity, trench velocity, and subduction partitioning

    NARCIS (Netherlands)

    Schellart, W. P.; Stegman, D. R.; Farrington, R. J.; Moresi, L.

    2011-01-01

    Subduction of oceanic lithosphere occurs through both trenchward subducting plate motion and trench retreat. We investigate how subducting plate velocity, trench velocity and the partitioning of these two velocity components vary for individual subduction zone segments as a function of proximity to

  16. Mean Velocity vs. Mean Propulsive Velocity vs. Peak Velocity: Which Variable Determines Bench Press Relative Load With Higher Reliability?

    Science.gov (United States)

    García-Ramos, Amador; Pestaña-Melero, Francisco L; Pérez-Castilla, Alejandro; Rojas, Francisco J; Gregory Haff, G

    2018-05-01

    García-Ramos, A, Pestaña-Melero, FL, Pérez-Castilla, A, Rojas, FJ, and Haff, GG. Mean velocity vs. mean propulsive velocity vs. peak velocity: which variable determines bench press relative load with higher reliability? J Strength Cond Res 32(5): 1273-1279, 2018-This study aimed to compare between 3 velocity variables (mean velocity [MV], mean propulsive velocity [MPV], and peak velocity [PV]): (a) the linearity of the load-velocity relationship, (b) the accuracy of general regression equations to predict relative load (%1RM), and (c) the between-session reliability of the velocity attained at each percentage of the 1-repetition maximum (%1RM). The full load-velocity relationship of 30 men was evaluated by means of linear regression models in the concentric-only and eccentric-concentric bench press throw (BPT) variants performed with a Smith machine. The 2 sessions of each BPT variant were performed within the same week separated by 48-72 hours. The main findings were as follows: (a) the MV showed the strongest linearity of the load-velocity relationship (median r = 0.989 for concentric-only BPT and 0.993 for eccentric-concentric BPT), followed by MPV (median r = 0.983 for concentric-only BPT and 0.980 for eccentric-concentric BPT), and finally PV (median r = 0.974 for concentric-only BPT and 0.969 for eccentric-concentric BPT); (b) the accuracy of the general regression equations to predict relative load (%1RM) from movement velocity was higher for MV (SEE = 3.80-4.76%1RM) than for MPV (SEE = 4.91-5.56%1RM) and PV (SEE = 5.36-5.77%1RM); and (c) the PV showed the lowest within-subjects coefficient of variation (3.50%-3.87%), followed by MV (4.05%-4.93%), and finally MPV (5.11%-6.03%). Taken together, these results suggest that the MV could be the most appropriate variable for monitoring the relative load (%1RM) in the BPT exercise performed in a Smith machine.

  17. The effect of thermal velocities on structure formation in N-body simulations of warm dark matter

    Science.gov (United States)

    Leo, Matteo; Baugh, Carlton M.; Li, Baojiu; Pascoli, Silvia

    2017-11-01

    We investigate the impact of thermal velocities in N-body simulations of structure formation in warm dark matter models. Adopting the commonly used approach of adding thermal velocities, randomly selected from a Fermi-Dirac distribution, to the gravitationally-induced velocities of the simulation particles, we compare the matter and velocity power spectra measured from CDM and WDM simulations, in the latter case with and without thermal velocities. This prescription for adding thermal velocities introduces numerical noise into the initial conditions, which influences structure formation. At early times, the noise affects dramatically the power spectra measured from simulations with thermal velocities, with deviations of the order of ~ Script O(10) (in the matter power spectra) and of the order of ~ Script O(102) (in the velocity power spectra) compared to those extracted from simulations without thermal velocities. At late times, these effects are less pronounced with deviations of less than a few percent. Increasing the resolution of the N-body simulation shifts these discrepancies to higher wavenumbers. We also find that spurious haloes start to appear in simulations which include thermal velocities at a mass that is ~3 times larger than in simulations without thermal velocities.

  18. Analysis of photosynthate translocation velocity and measurement of weighted average velocity in transporting pathway of crops

    International Nuclear Information System (INIS)

    Ge Cailin; Luo Shishi; Gong Jian; Zhang Hao; Ma Fei

    1996-08-01

    The translocation profile pattern of 14 C-photosynthate along the transporting pathway in crops were monitored by pulse-labelling a mature leaf with 14 CO 2 . The progressive spreading of translocation profile pattern along the sheath or stem indicates that the translocation of photosynthate along the sheath or stem proceed with a range of velocities rather than with just a single velocity. The method for measuring the weighted average velocity of photosynthate translocation along the sheath or stem was established in living crops. The weighted average velocity and the maximum velocity of photosynthate translocation along the sheath in rice and maize were measured actually. (4 figs., 3 tabs.)

  19. No Effect of Assisted Hip Rotation on Bat Velocity

    Science.gov (United States)

    RIVERA, MICHELLE; LEYVA, WHITNEY D.; ARCHER, DAVID C.; MUNGER, CAMERON N.; WATKINS, CASEY M.; WONG, MEGAN A.; DOBBS, IAN J.; GALPIN, ANDREW J.; COBURN, JARED W.; BROWN, LEE E.

    2018-01-01

    Softball and baseball are games that require multiple skill sets such as throwing, hitting and fielding. Players spend a copious amount of time in batting practice in order to be successful hitters. Variables commonly associated with successful hitting include bat velocity and torso rotation. The concept of overspeed bodyweight assistance (BWA) has shown increases in vertical jump and sprint times, but not hip rotation and batting. The purpose of this study was to examine the effects of assisted hip rotation on bat velocity. Twenty-one male and female recreational softball and baseball players (15 males, age 23.8 ± 3.1yrs; height 177.67 ± 6.71cm; body mass 85.38 ± 14.83kg; 6 females, age 21.5 ± 2.1yrs; height 162.20 ± 9.82cm; body mass 60.28 ± 9.72kg) volunteered to participate. Four different BWA conditions (0%, 10%, 20%, and 30%) were randomly applied and their effects on bat velocity were analyzed. Subjects performed three maximal effort swings under each condition in a custom measurement device and average bat velocity (MPH) was used for analysis. A mixed factor ANOVA revealed no interaction (p=0.841) or main effect for condition, but there was a main effect for sex where males had greater bat velocity (43.82±4.40 - 0% BWA, 41.52±6.09 - 10% BWA, 42.59±7.24 - 20% BWA, 42.69±6.42 - 30% BWA) than females (32.57±5.33 - 0% BWA, 31.69±3.40 - 10% BWA, 32.43±5.06 - 20% BWA, 32.08±4.83 - 30% BWA) across all conditions Using the concept of overspeed training with assisted hip rotation up to 30% BWA did not result in an increase in bat velocity. Future research should examine elastic band angle and hip translation at set-up. PMID:29795730

  20. No Effect of Assisted Hip Rotation on Bat Velocity.

    Science.gov (United States)

    Rivera, Michelle; Leyva, Whitney D; Archer, David C; Munger, Cameron N; Watkins, Casey M; Wong, Megan A; Dobbs, Ian J; Galpin, Andrew J; Coburn, Jared W; Brown, Lee E

    2018-01-01

    Softball and baseball are games that require multiple skill sets such as throwing, hitting and fielding. Players spend a copious amount of time in batting practice in order to be successful hitters. Variables commonly associated with successful hitting include bat velocity and torso rotation. The concept of overspeed bodyweight assistance (BWA) has shown increases in vertical jump and sprint times, but not hip rotation and batting. The purpose of this study was to examine the effects of assisted hip rotation on bat velocity. Twenty-one male and female recreational softball and baseball players (15 males, age 23.8 ± 3.1yrs; height 177.67 ± 6.71cm; body mass 85.38 ± 14.83kg; 6 females, age 21.5 ± 2.1yrs; height 162.20 ± 9.82cm; body mass 60.28 ± 9.72kg) volunteered to participate. Four different BWA conditions (0%, 10%, 20%, and 30%) were randomly applied and their effects on bat velocity were analyzed. Subjects performed three maximal effort swings under each condition in a custom measurement device and average bat velocity (MPH) was used for analysis. A mixed factor ANOVA revealed no interaction (p=0.841) or main effect for condition, but there was a main effect for sex where males had greater bat velocity (43.82±4.40 - 0% BWA, 41.52±6.09 - 10% BWA, 42.59±7.24 - 20% BWA, 42.69±6.42 - 30% BWA) than females (32.57±5.33 - 0% BWA, 31.69±3.40 - 10% BWA, 32.43±5.06 - 20% BWA, 32.08±4.83 - 30% BWA) across all conditions Using the concept of overspeed training with assisted hip rotation up to 30% BWA did not result in an increase in bat velocity. Future research should examine elastic band angle and hip translation at set-up.

  1. Performance of a vector velocity estimator

    DEFF Research Database (Denmark)

    Munk, Peter; Jensen, Jørgen Arendt

    1998-01-01

    tracking can be found in the literature, but no method with a satisfactory performance has been found that can be used in a commercial implementation. A method for estimation of the velocity vector is presented. Here an oscillation transverse to the ultrasound beam is generated, so that a transverse motion...... in an autocorrelation approach that yields both the axial and the lateral velocity, and thus the velocity vector. The method has the advantage that a standard array transducer and a modified digital beamformer, like those used in modern ultrasound scanners, is sufficient to obtain the information needed. The signal...

  2. Balance Velocities of the Greenland Ice Sheet

    Science.gov (United States)

    Joughin, Ian; Fahnestock, Mark; Ekholm, Simon; Kwok, Ron

    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 altimetry data, yields far greater detail than earlier balance velocity estimates for Greenland. The velocity contours reveal in striking detail the location of an ice stream in northeastern Greenland, which was only recently discovered using satellite imagery. Enhanced flow associated with all of the major outlets is clearly visible, although small errors in the source data result in less accurate estimates of the absolute flow speeds. Nevertheless, the balance map is useful for ice-sheet modelling, mass balance studies, and field planning.

  3. Superhilac real-time velocity measurements

    International Nuclear Information System (INIS)

    Feinberg, B.; Meaney, D.; Thatcher, R.; Timossi, C.

    1987-03-01

    Phase probes have been placed in several external beam lines at the LBL heavy ion linear accelerator (SuperHILAC) to provide non-destructive velocity measurements independent of the ion being accelerated. The existing system has been improved to provide the following features: a display refresh rate better than twice per second, a sensitive pseudo-correlation technique to pick out the signal from the noise, simultaneous measurements of up to four ion velocities when more than one beam is being accelerated, and a touch-screen operator interface. These improvements allow the system to be used as a routine tuning aid and beam velocity monitor

  4. Sound velocity in potassium hydroxide aqueous solution

    International Nuclear Information System (INIS)

    Tsapuryan, Kh.D.; Aleksandrov, A.A.; Kochetkov, A.I.

    1992-01-01

    Measurements of ultrasonic velocities in potassium hydroxide aqueous solutions are carried out within the frames of studies on improvement of water chemistry in NPP cooling systems. Method of echo pulses superposition with acoustic path length of 41.447 mm is used for measurements. The measurements are performed at 2.6 MHz frequency. Complex temperature dependence of ultrasonic velocity is determined. Ultrasonic velocity dependence on pressure is close to linear one. The formula for calculation of thermodynamic properties of the studied solutions on the basis of experimental data obtained is proposed

  5. Neutron stars velocities and magnetic fields

    Science.gov (United States)

    Paret, Daryel Manreza; Martinez, A. Perez; Ayala, Alejandro.; Piccinelli, G.; Sanchez, A.

    2018-01-01

    We study a model that explain neutron stars velocities due to the anisotropic emission of neutrinos. Strong magnetic fields present in neutron stars are the source of the anisotropy in the system. To compute the velocity of the neutron star we model its core as composed by strange quark matter and analice the properties of a magnetized quark gas at finite temperature and density. Specifically we have obtained the electron polarization and the specific heat of magnetized fermions as a functions of the temperature, chemical potential and magnetic field which allow us to study the velocity of the neutron star as a function of these parameters.

  6. Shuttlecock Velocity of a Badminton Drop Shot

    Directory of Open Access Journals (Sweden)

    Ampharin Ongvises

    2013-01-01

    Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

  7. Shuttlecock Velocity of a Badminton Drop Shot

    Directory of Open Access Journals (Sweden)

    Ampharin Ongvises

    2013-12-01

    Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

  8. 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.

  9. Modeling non-Fickian dispersion by use of the velocity PDF on the pore scale

    Science.gov (United States)

    Kooshapur, Sheema; Manhart, Michael

    2015-04-01

    For obtaining a description of reactive flows in porous media, apart from the geometrical complications of resolving the velocities and scalar values, one has to deal with the additional reactive term in the transport equation. An accurate description of the interface of the reacting fluids - which is strongly influenced by dispersion- is essential for resolving this term. In REV-based simulations the reactive term needs to be modeled taking sub-REV fluctuations and possibly non-Fickian dispersion into account. Non-Fickian dispersion has been observed in strongly heterogeneous domains and in early phases of transport. A fully resolved solution of the Navier-Stokes and transport equations which yields a detailed description of the flow properties, dispersion, interfaces of fluids, etc. however, is not practical for domains containing more than a few thousand grains, due to the huge computational effort required. Through Probability Density Function (PDF) based methods, the velocity distribution in the pore space can facilitate the understanding and modelling of non-Fickian dispersion [1,2]. Our aim is to model the transition between non-Fickian and Fickian dispersion in a random sphere pack within the framework of a PDF based transport model proposed by Meyer and Tchelepi [1,3]. They proposed a stochastic transport model where velocity components of tracer particles are represented by a continuous Markovian stochastic process. In addition to [3], we consider the effects of pore scale diffusion and formulate a different stochastic equation for the increments in velocity space from first principles. To assess the terms in this equation, we performed Direct Numerical Simulations (DNS) for solving the Navier-Stokes equation on a random sphere pack. We extracted the PDFs and statistical moments (up to the 4th moment) of the stream-wise velocity, u, and first and second order velocity derivatives both independent and conditioned on velocity. By using this data and

  10. Determination of the filtration velocities and mean velocity in ground waters using radiotracers

    International Nuclear Information System (INIS)

    Duran P, Oscar; Diaz V, Francisco; Heresi M, Nelida

    1994-01-01

    An experimental method to determine filtration, or, Darcy velocity and mean velocity in underground waters using radiotracers, is described. After selecting the most appropriate tracers, from 6 chemical compounds, to measure water velocity, a method to measure filtration velocity was developed. By fully labelling the water column with 2 radioisotopes, Br and tritium, almost identical values were obtained for the aquifer filtration velocity in the sounding S1. This value was 0.04 m/d. Field porosity was calculated at 11% and mean velocity at 0.37 m.d. With the filtration velocity value and knowing the hydraulic variation between the soundings S1 and S2 placed at 10 meters, field permeability was estimated at 2.4 x 10 m/s. (author)

  11. Development and validity of a scale of perception of velocity in resistance exercise.

    Science.gov (United States)

    Bautista, Iker J; Chirosa, Ignacio J; Chirosa, Luis J; Martín, Ignacio; González, Andrés; Robertson, Robert J

    2014-09-01

    This aims of this study were twofold; 1) to development a new scale of perceived velocity in the bench press exercise and 2) to examine the scales concurrent validity. Twenty one physically active males with mean ±SD age, height and weights of: 27.5 ± 4.7 years, 1.77 ± 0.07 m, and 79.8 ± 10.3 kg respectively, took part in the study. The criterion variable used to test the validity of the new scale was the mean execution velocity (Velreal) of the bench press exercise. Three intensities (light loads [ 70% 1RM]) were measured randomly during 5 days of testing. Perceived velocity (Velscale) was measured immediately after each exercise set using the new scale. A positive linear correlation (r range = 0.69 to 0.81) was found in all three intensities, analyzed individually, between the Velreal and Velscale. Pearson correlations showed a greater frequency of scale use resulted higher correlation values (range r = 0.88 to 0.96). This study provides evidence of the concurrent validity of a new scale of perceived velocity in the bench press exercise in trained adult males. These results suggest the exercise intensity of the bench press can be quantified quickly and effective using this new scale of perceived velocity, particularly when training for maximum power. Key PointsMeasurement of perception of velocity can complement other scales of perception such as the 15 category Borg scale or the OMNI-RES.The results obtained in this study show that there was a positive correlation between the perceived velocity measured by the scale and actual velocityRegular use of the new scale of perceived velocity in external resistance training provides athletes with continuous feedback of execution velocity in each repetition and set, especially with high power loads.

  12. Hybrid method for determining the parameters of condenser microphones from measured membrane velocities and numerical calculations

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2009-01-01

    to this problem is to measure the velocity distribution of the membrane by means of a non-contact method, such as laser vibrometry. The measured velocity distribution can be used together with a numerical formulation such as the boundary element method for estimating the microphone response and other parameters......, e.g., the acoustic center. In this work, such a hybrid method is presented and examined. The velocity distributions of a number of condenser microphones have been determined using a laser vibrometer, and these measured velocity distributions have been used for estimating microphone responses......Typically, numerical calculations of the pressure, free-field, and random-incidence response of a condenser microphone are carried out on the basis of an assumed displacement distribution of the diaphragm of the microphone; the conventional assumption is that the displacement follows a Bessel...

  13. Low-velocity superconducting accelerating structures

    International Nuclear Information System (INIS)

    Delayen, J.R.

    1990-01-01

    The present paper reviews the status of RF superconductivity as applied to low-velocity accelerating properties. Heavy-ion accelerators must accelerate efficiently particles which travel at a velocity much smaller than that of light particles, whose velocity changes along accelerator, and also different particles which have different velocity profiles. Heavy-ion superconducting accelerators operate at frequencies which are lower than high-energy superconducting accelerators. The present paper first discusses the basic features of heavy-ion superconducting structures and linacs. Design choices are then addressed focusing on structure geometry, materials, frequency, phase control, and focusing. The report also gives an outline of the status of superconducting booster projects currently under way at the Argonne National Laboratory, SUNY Stony Brook, Weizmann Institute, University of Washington, Florida State, Saclay, Kansas State, Daresbury, Japanese Atomic Energy Research Institute, Legnaro, Bombay, Sao Paulo, ANU (Canberra), and Munich. Recent developments and future prospects are also described. (N.K.) 68 refs

  14. Wave Velocity Estimation in Heterogeneous Media

    KAUST Repository

    Asiri, Sharefa M.; Laleg-Kirati, Taous-Meriem

    2016-01-01

    In this paper, modulating functions-based method is proposed for estimating space-time dependent unknown velocity in the wave equation. The proposed method simplifies the identification problem into a system of linear algebraic equations. Numerical

  15. Ultrasonic velocity measurements in expanded liquid mercury

    International Nuclear Information System (INIS)

    Suzuki, K.; Inutake, M.; Fujiwaka, S.

    1977-10-01

    In this paper we present the first results of the sound velocity measurements in expanded liquid mercury. The measurements were made at temperatures up to 1600 0 C and pressures up to 1700 kg/cm 2 by means of an ultrasonic pulse transmission/echo technique which was newly developed for such high temperature/pressure condition. When the density is larger than 9 g/cm 3 , the observed sound velocity decreases linearly with decreasing density. At densities smaller than 9 g/cm 3 , the linear dependence on the density is no longer observed. The observed sound velocity approaches a minimum near the liquid-gas critical point (rho sub(cr) asymptotically equals 5.5 g/cm 3 ). The existing theories for sound velocity in liquid metals fail to explain the observed results. (auth.)

  16. Spectator-velocity pions from heavy ions

    International Nuclear Information System (INIS)

    Rasmussen, J.; Ridout, J.; Murphy, D.; Radi, H.M.A.

    1982-11-01

    The discussion centers on pions in the velocity regions of target and projectile, where strong spectral features appear. The topics covered include stopped-pion studies, and convoy pions in the projectile frame

  17. Imaging chemical reactions - 3D velocity mapping

    Science.gov (United States)

    Chichinin, A. I.; Gericke, K.-H.; Kauczok, S.; Maul, C.

    Visualising a collision between an atom or a molecule or a photodissociation (half-collision) of a molecule on a single particle and single quantum level is like watching the collision of billiard balls on a pool table: Molecular beams or monoenergetic photodissociation products provide the colliding reactants at controlled velocity before the reaction products velocity is imaged directly with an elaborate camera system, where one should keep in mind that velocity is, in general, a three-dimensional (3D) vectorial property which combines scattering angles and speed. If the processes under study have no cylindrical symmetry, then only this 3D product velocity vector contains the full information of the elementary process under study.

  18. Spectral Velocity Estimation in the Transverse Direction

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2013-01-01

    A method for estimating the velocity spectrum for a fully transverse flow at a beam-to-flow angle of 90is described. The approach is based on the transverse oscillation (TO) method, where an oscillation across the ultrasound beam is made during receive processing. A fourth-order estimator based...... on the correlation of the received signal is derived. A Fourier transform of the correlation signal yields the velocity spectrum. Performing the estimation for short data segments gives the velocity spectrum as a function of time as for ordinary spectrograms, and it also works for a beam-to-flow angle of 90...... estimation scheme can reliably find the spectrum at 90, where a traditional estimator yields zero velocity. Measurements have been conducted with the SARUS experimental scanner and a BK 8820e convex array transducer (BK Medical, Herlev, Denmark). A CompuFlow 1000 (Shelley Automation, Inc, Toronto, Canada...

  19. The critical ionization velocity - a bibliography

    International Nuclear Information System (INIS)

    Axnaes, I.; Brenning, N.; Raadu, M.A.

    1982-12-01

    A list of all relevant contributions, known to the authors, concerning the critical ionization velocity phenomena is presented. The contributions are classified and described in a few sentences. (Authors)

  20. The species velocity of trees in Alaska

    Science.gov (United States)

    Morrison, B. D.; Napier, J.; de Lafontaine, G.; Heath, K.; Li, B.; Hu, F.; Greenberg, J. A.

    2017-12-01

    Anthropogenic climate change has motivated interest in the paleo record to enhance our knowledge about past vegetation responses to climate change and help understand potential responses in the future. Additionally, polar regions currently experience the most rapid rates of climate change globally, prompting concern over changes in the ecological composition of high latitude ecosystems. Recent analyses have attempted to construct methods to estimate a species' ability to track climate change by computing climate velocity; a measure of the rate of climate displacement across a landscape which may indicate the speed an organism must migrate to keep pace with climate change. However, a challenge to using climate velocity in understanding range shifts is a lack of species-specificity in the velocity calculations: climate velocity does not actually use any species data in its analysis. To solve the shortcomings of climate velocity in estimating species displacement rates, we computed the "species velocity" of white spruce, green and grey alder populations across the state of Alaska from the Last Glacial Maximum (LGM) to today. Species velocity represents the rate and direction a species is required to migrate to keep pace with a changing climate following the LGM. We used a species distribution model to determine past and present white spruce and alder distributions using statistically downscaled climate data at 60m. Species velocity was then derived from the change in species distribution per year by the change in distribution over Alaska (km/yr). High velocities indicate locations where the species environmental envelope is changing drastically and must disperse rapidly to survive climate change. As a result, high velocity regions are more vulnerable to distribution shifts and higher risk of local extinction. Conversely, low species velocities indicate locations where the local climate envelope is shifting relatively slowly, reducing the stress to disperse quickly

  1. Experimental investigation of ultrasonic velocity anisotropy in ...

    Indian Academy of Sciences (India)

    Permanent link: https://www.ias.ac.in/article/fulltext/pram/077/02/0345-0355. Keywords. Magnetic fluids; ultrasonic wave; sound velocity; anisotropy. Abstract. Magnetic field-induced dispersion of ultrasonic velocity in a Mn0.7Zn0.3Fe2O4 fluid (applied magnetic field is perpendicular to the ultrasonic propagation vector) is ...

  2. Jovian cloud structure and velocity fields

    International Nuclear Information System (INIS)

    Mitchell, J.L.; Terrile, R.J.; Collins, S.A.; Smith, B.A.; Muller, J.P.; Ingersoll, A.P.; Hunt, G.E.; Beebe, R.F.

    1979-01-01

    A regional comparison of the cloud structures and velocity fields (meridional as well as zonal velocities) in the jovian atmosphere (scales > 200 km) as observed by the Voyager 1 imaging system is given. It is shown that although both hemispheres of Jupiter show similar patterns of diminishing and alternating eastward and westward jets as one progresses polewards, there is a pronounced asymmetry in the structural appearance of the two hemispheres. (UK)

  3. On the velocity of the Vela pulsar

    OpenAIRE

    Gvaramadze, Vasilii

    2000-01-01

    It is shown that if the shell of the Vela supernova remnant is responsible for nearly all the scattering of the Vela pulsar, then the scintillation and proper motion velocities of the pulsar can only be reconciled with each other in the case of nonzero transverse velocity of the scattering material. A possible origin of large-scale transverse motions in the shell of the Vela supernova remnant is discussed.

  4. On the velocity of the Vela pulsar

    Science.gov (United States)

    Gvaramadze, V.

    2001-04-01

    It is shown that if the shell of the Vela supernova remnant is responsible for nearly all the scattering of the Vela pulsar, then the scintillation and proper motion velocities of the pulsar can only be reconciled with each other in the case of nonzero transverse velocity of the scattering material. A possible origin of large-scale transverse motions in the shell of the Vela supernova remnant is discussed.

  5. Velocity Memory Effect for polarized gravitational waves

    Science.gov (United States)

    Zhang, P.-M.; Duval, C.; Gibbons, G. W.; Horvathy, P. A.

    2018-05-01

    Circularly polarized gravitational sandwich waves exhibit, as do their linearly polarized counterparts, the Velocity Memory Effect: freely falling test particles in the flat after-zone fly apart along straight lines with constant velocity. In the inside zone their trajectories combine oscillatory and rotational motions in a complicated way. For circularly polarized periodic gravitational waves some trajectories remain bounded, while others spiral outward. These waves admit an additional "screw" isometry beyond the usual five. The consequences of this extra symmetry are explored.

  6. Random magnetism

    International Nuclear Information System (INIS)

    Tsallis, C.

    1980-03-01

    The 'ingredients' which control a phase transition in well defined system as well as in random ones (e.g. random magnetic systems) are listed and discussed within a somehow unifying perspective. Among these 'ingredients' we find the couplings and elements responsible for the cooperative phenomenon, the topological connectivity as well as possible topological incompatibilities, the influence of new degrees of freedom, the order parameter dimensionality, the ground state degeneracy and finally the 'quanticity' of the system. The general trends, though illustrated in magnetic systems, essentially hold for all phase transitions, and give a basis for connection of this area with Field theory, Theory of dynamical systems, etc. (Author) [pt

  7. Random magnetism

    International Nuclear Information System (INIS)

    Tsallis, C.

    1981-01-01

    The 'ingredients' which control a phase transition in well defined systems as well as in random ones (e.q. random magnetic systems) are listed and discussed within a somehow unifying perspective. Among these 'ingredients' the couplings and elements responsible for the cooperative phenomenon, the topological connectivity as well as possible topological incompatibilities, the influence of new degrees of freedom, the order parameter dimensionality, the ground state degeneracy and finally the 'quanticity' of the system are found. The general trends, though illustrated in magnetic systems, essentially hold for all phase transitions, and give a basis for connection of this area with Field theory, Theory of dynamical systems, etc. (Author) [pt

  8. Velocity navigator for motion compensated thermometry.

    Science.gov (United States)

    Maier, Florian; Krafft, Axel J; Yung, Joshua P; Stafford, R Jason; Elliott, Andrew; Dillmann, Rüdiger; Semmler, Wolfhard; Bock, Michael

    2012-02-01

    Proton resonance frequency shift thermometry is sensitive to breathing motion that leads to incorrect phase differences. In this work, a novel velocity-sensitive navigator technique for triggering MR thermometry image acquisition is presented. A segmented echo planar imaging pulse sequence was modified for velocity-triggered temperature mapping. Trigger events were generated when the estimated velocity value was less than 0.2 cm/s during the slowdown phase in parallel to the velocity-encoding direction. To remove remaining high-frequency spikes from pulsation in real time, a Kalman filter was applied to the velocity navigator data. A phantom experiment with heating and an initial volunteer experiment without heating were performed to show the applicability of this technique. Additionally, a breath-hold experiment was conducted for comparison. A temperature rise of ΔT = +37.3°C was seen in the phantom experiment, and a root mean square error (RMSE) outside the heated region of 2.3°C could be obtained for periodic motion. In the volunteer experiment, a RMSE of 2.7°C/2.9°C (triggered vs. breath hold) was measured. A novel velocity navigator with Kalman filter postprocessing in real time significantly improves the temperature accuracy over non-triggered acquisitions and suggests being comparable to a breath-held acquisition. The proposed technique might be clinically applied for monitoring of thermal ablations in abdominal organs.

  9. High-velocity frictional properties of gabbro

    Science.gov (United States)

    Tsutsumi, Akito; Shimamoto, Toshihiko

    High-velocity friction experiments have been performed on a pair of hollow-cylindrical specimens of gabbro initially at room temperature, at slip rates from 7.5 mm/s to 1.8 m/s, with total circumferential displacements of 125 to 174 m, and at normal stresses to 5 MPa, using a rotary-shear high-speed friction testing machine. Steady-state friction increases slightly with increasing slip rate at slip rates to about 100 mm/s (velocity strengthening) and it decreases markedly with increasing slip rate at higher velocities (velocity weakening). Steady-state friction in the velocity weakening regime is lower for the non-melting case than the frictional melting case, due perhaps to severe thermal fracturing. A very large peak friction is always recognized upon the initiation of visible frictional melting, presumably owing to the welding of fault surfaces upon the solidification of melt patches. Frictional properties thus change dramatically with increasing displacement at high velocities, and such a non-linear effect must be incorporated into the analysis of earthquake initiation processes.

  10. A dual-phantom system for validation of velocity measurements in stenosis models under steady flow.

    Science.gov (United States)

    Blake, James R; Easson, William J; Hoskins, Peter R

    2009-09-01

    A dual-phantom system is developed for validation of velocity measurements in stenosis models. Pairs of phantoms with identical geometry and flow conditions are manufactured, one for ultrasound and one for particle image velocimetry (PIV). The PIV model is made from silicone rubber, and a new PIV fluid is made that matches the refractive index of 1.41 of silicone. Dynamic scaling was performed to correct for the increased viscosity of the PIV fluid compared with that of the ultrasound blood mimic. The degree of stenosis in the models pairs agreed to less than 1%. The velocities in the laminar flow region up to the peak velocity location agreed to within 15%, and the difference could be explained by errors in ultrasound velocity estimation. At low flow rates and in mild stenoses, good agreement was observed in the distal flow fields, excepting the maximum velocities. At high flow rates, there was considerable difference in velocities in the poststenosis flow field (maximum centreline differences of 30%), which would seem to represent real differences in hydrodynamic behavior between the two models. Sources of error included: variation of viscosity because of temperature (random error, which could account for differences of up to 7%); ultrasound velocity estimation errors (systematic errors); and geometry effects in each model, particularly because of imperfect connectors and corners (systematic errors, potentially affecting the inlet length and flow stability). The current system is best placed to investigate measurement errors in the laminar flow region rather than the poststenosis turbulent flow region.

  11. Consideration of some difficulties in migration velocity analysis; Migration velocity analysis no shomondai ni kansuru kento

    Energy Technology Data Exchange (ETDEWEB)

    Akama, K [Japan National Oil Corp., Tokyo (Japan). Technology Research Center; Matsuoka, T [Japan Petroleum Exploration Corp., Tokyo (Japan)

    1997-10-22

    Concerning migration velocity analysis in the seismic exploration method, two typical techniques, out of velocity analysis techniques using residual moveout in the CIP gather, are verified. Deregowski`s method uses pre-stacking deep-level migration records for velocity analysis to obtain velocities free of spatial inconsistency and not dependent on the velocity structure. This method is very like the conventional DMO velocity analysis method and is easy to understand intuitively. In this method, however, error is apt to be aggravated in the process of obtaining the depth-sector velocity from the time-RMS velocity. Al-Yahya`s method formulates the moveout residual in the CIP gather. This assumes horizontal stratification and a small residual velocity, however, and fails to guarantee convergence in the case of a steep structure or a grave model error. In the updating of the velocity model, in addition, it has to maintain required accuracy and, at the same time, incorporate smoothing to ensure not to deteriorate high convergence. 2 refs., 5 figs.

  12. Exploration of probability distribution of velocities of saltating sand particles based on the stochastic particle-bed collisions

    International Nuclear Information System (INIS)

    Zheng Xiaojing; Xie Li; Zhou Youhe

    2005-01-01

    The wind-blown sand saltating movement is mainly categorized into two mechanical processes, that is, the interaction between the moving sand particles and the wind in the saltation layer, and the collisions of incident particles with sand bed, and the latter produces a lift-off velocity of a sand particle moving into saltation. In this Letter a methodology of phenomenological analysis is presented to get probability density (distribution) function (pdf) of the lift-off velocity of sand particles from sand bed based on the stochastic particle-bed collision. After the sand particles are dealt with by uniform circular disks and a 2D collision between an incident particle and the granular bed is employed, we get the analytical formulas of lift-off velocity of ejected and rebound particles in saltation, which are functions of some random parameters such as angle and magnitude of incident velocity of the impacting particles, impact and contact angles between the collision particles, and creeping velocity of sand particles, etc. By introducing the probability density functions (pdf's) of these parameters in communion with all possible patterns of sand bed and all possible particle-bed collisions, and using the essential arithmetic of multi-dimension random variables' pdf, the pdf's of lift-off velocities are deduced out and expressed by the pdf's of the random parameters in the collisions. The numerical results of the distributions of lift-off velocities display that they agree well with experimental ones

  13. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J.C.; Ibrahim, S.R.; Brincker, Rune

    Abstraet Thispaper demansirates how to use the Random Decrement (RD) technique for identification o flinear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing...

  14. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune

    This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...

  15. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, R.; Brincker, Rune

    1998-01-01

    This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...

  16. Random dynamics

    International Nuclear Information System (INIS)

    Bennett, D.L.; Brene, N.; Nielsen, H.B.

    1986-06-01

    The goal of random dynamics is the derivation of the laws of Nature as we know them (standard model) from inessential assumptions. The inessential assumptions made here are expressed as sets of general models at extremely high energies: gauge glass and spacetime foam. Both sets of models lead tentatively to the standard model. (orig.)

  17. Random dynamics

    International Nuclear Information System (INIS)

    Bennett, D.L.

    1987-01-01

    The goal of random dynamics is the derivation of the laws of Nature as we know them (standard model) from inessential assumptions. The inessential assumptions made here are expressed as sets of general models at extremely high energies: Gauge glass and spacetime foam. Both sets of models lead tentatively to the standard model. (orig.)

  18. Random Dynamics

    Science.gov (United States)

    Bennett, D. L.; Brene, N.; Nielsen, H. B.

    1987-01-01

    The goal of random dynamics is the derivation of the laws of Nature as we know them (standard model) from inessential assumptions. The inessential assumptions made here are expressed as sets of general models at extremely high energies: gauge glass and spacetime foam. Both sets of models lead tentatively to the standard model.

  19. Predicting vertical jump height from bar velocity.

    Science.gov (United States)

    García-Ramos, Amador; Štirn, Igor; Padial, Paulino; Argüelles-Cienfuegos, Javier; De la Fuente, Blanca; Strojnik, Vojko; Feriche, Belén

    2015-06-01

    The objective of the study was to assess the use of maximum (Vmax) and final propulsive phase (FPV) bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s(-2)). Vertical jump height was calculated from the take-off velocity (Vtake-off) provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the Vmax and FPV recorded by the linear velocity transducer. Vmax (y = 16.577x - 16.384) was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504) was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and Vtake-off was observed (r(2) = 0.307), while the differences between Vmax and Vtake-off were homogenously distributed (r(2) = 0.071). These results suggest that Vmax is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine. Key pointsVertical jump height in the loaded jump squat can be estimated with acceptable precision from the maximum bar velocity recorded by a linear velocity transducer.The relationship between the point at which bar acceleration is less than -9.81 m·s(-2) and the real take-off is affected by the velocity of movement.Mean propulsive velocity recorded by a linear velocity transducer does not appear to be optimal to monitor ballistic exercise performance.

  20. Referencing geostrophic velocities using ADCP data Referencing geostrophic velocities using ADCP data

    Directory of Open Access Journals (Sweden)

    Isis Comas-Rodríguez

    2010-06-01

    Full Text Available Acoustic Doppler Current Profilers (ADCPs have proven to be a useful oceanographic tool in the study of ocean dynamics. Data from D279, a transatlantic hydrographic cruise carried out in spring 2004 along 24.5°N, were processed, and lowered ADCP (LADCP bottom track data were used to assess the choice of reference velocity for geostrophic calculations. The reference velocities from different combinations of ADCP data were compared to one another and a reference velocity was chosen based on the LADCP data. The barotropic tidal component was subtracted to provide a final reference velocity estimated by LADCP data. The results of the velocity fields are also shown. Further studies involving inverse solutions will include the reference velocity calculated here.

  1. Propagation Velocity of Solid Earth Tides

    Science.gov (United States)

    Pathak, S.

    2017-12-01

    One of the significant considerations in most of the geodetic investigations is to take into account the outcome of Solid Earth tides on the location and its consequent impact on the time series of coordinates. In this research work, the propagation velocity resulting from the Solid Earth tides between the Indian stations is computed. Mean daily coordinates for the stations have been computed by applying static precise point positioning technique for a day. The computed coordinates are used as an input for computing the tidal displacements at the stations by Gravity method along three directions at 1-minute interval for 24 hours. Further the baseline distances are computed between four Indian stations. Computation of the propagation velocity for Solid Earth tides can be done by the virtue of study of the concurrent effect of it in-between the stations of identified baseline distance along with the time consumed by the tides for reaching from one station to another. The propagation velocity helps in distinguishing the impact at any station if the consequence at a known station for a specific time-period is known. Thus, with the knowledge of propagation velocity, the spatial and temporal effects of solid earth tides can be estimated with respect to a known station. As theoretically explained, the tides generated are due to the position of celestial bodies rotating about Earth. So the need of study is to observe the correlation of propagation velocity with the rotation speed of the Earth. The propagation velocity of Solid Earth tides comes out to be in the range of 440-470 m/s. This velocity comes out to be in a good agreement with the Earth's rotation speed.

  2. Pulsar velocity observations: Correlations, interpretations, and discussion

    International Nuclear Information System (INIS)

    Helfand, D.J.; Tademaru, E.

    1977-01-01

    From an examination of the current sample of 12 pulsars with measured proper motions and the z-distribution of the much larger group of over 80 sources with measured period derivatives, we develop a self-consistent picture of pulsar evolution. The apparent tendency of pulsars to move parallel to the galactic plane is explained as the result of various selection effects. A method for calculating the unmeasurable radial velocity of a pulsar is presented; it is shown that the total space velocities thus obtained are consistent with the assumption of an extreme Population I origin for pulsars which subsequently move away from the plane with a large range of velocities. The time scale for pulsar magnetic field decay is derived from dynamical considerations. A strong correlation of the original pulsar field strength with the magnitude of pulsar velocity is discussed. This results in the division of pulsars into two classes: Class A sources characterized by low space velocities, a small scale height, and low values of P 0 P 0 ; and Class B sources with a large range of velocities (up to 1000 km s -1 ), a much greater scale height, and larger values of initial field strength. It is postulated that Class A sources originate in tight binaries where their impulse acceleration at birth is insufficient to remove them from the system, while the Class B sources arise from single stars or loosely bound binaries and are accelerated to high velocities by their asymmetric radiation force. The evolutionary picture which is developed is shown to be consistent with a number of constraints imposed by supernova rates, the relative frequency of massive binaries and Class A sources, theoretical field-decay times, and the overall pulsar galactic distribution

  3. Microseismic Velocity Imaging of the Fracturing Zone

    Science.gov (United States)

    Zhang, H.; Chen, Y.

    2015-12-01

    Hydraulic fracturing of low permeability reservoirs can induce microseismic events during fracture development. For this reason, microseismic monitoring using sensors on surface or in borehole have been widely used to delineate fracture spatial distribution and to understand fracturing mechanisms. It is often the case that the stimulated reservoir volume (SRV) is determined solely based on microseismic locations. However, it is known that for some fracture development stage, long period long duration events, instead of microseismic events may be associated. In addition, because microseismic events are essentially weak and there exist different sources of noise during monitoring, some microseismic events could not be detected and thus located. Therefore the estimation of the SRV is biased if it is solely determined by microseismic locations. With the existence of fluids and fractures, the seismic velocity of reservoir layers will be decreased. Based on this fact, we have developed a near real time seismic velocity tomography method to characterize velocity changes associated with fracturing process. The method is based on double-difference seismic tomography algorithm to image the fracturing zone where microseismic events occur by using differential arrival times from microseismic event pairs. To take into account varying data distribution for different fracking stages, the method solves the velocity model in the wavelet domain so that different scales of model features can be obtained according to different data distribution. We have applied this real time tomography method to both acoustic emission data from lab experiment and microseismic data from a downhole microseismic monitoring project for shale gas hydraulic fracturing treatment. The tomography results from lab data clearly show the velocity changes associated with different rock fracturing stages. For the field data application, it shows that microseismic events are located in low velocity anomalies. By

  4. The SCEC Unified Community Velocity Model (UCVM) Software Framework for Distributing and Querying Seismic Velocity Models

    Science.gov (United States)

    Maechling, P. J.; Taborda, R.; Callaghan, S.; Shaw, J. H.; Plesch, A.; Olsen, K. B.; Jordan, T. H.; Goulet, C. A.

    2017-12-01

    Crustal seismic velocity models and datasets play a key role in regional three-dimensional numerical earthquake ground-motion simulation, full waveform tomography, modern physics-based probabilistic earthquake hazard analysis, as well as in other related fields including geophysics, seismology, and earthquake engineering. The standard material properties provided by a seismic velocity model are P- and S-wave velocities and density for any arbitrary point within the geographic volume for which the model is defined. Many seismic velocity models and datasets are constructed by synthesizing information from multiple sources and the resulting models are delivered to users in multiple file formats, such as text files, binary files, HDF-5 files, structured and unstructured grids, and through computer applications that allow for interactive querying of material properties. The Southern California Earthquake Center (SCEC) has developed the Unified Community Velocity Model (UCVM) software framework to facilitate the registration and distribution of existing and future seismic velocity models to the SCEC community. The UCVM software framework is designed to provide a standard query interface to multiple, alternative velocity models, even if the underlying velocity models are defined in different formats or use different geographic projections. The UCVM framework provides a comprehensive set of open-source tools for querying seismic velocity model properties, combining regional 3D models and 1D background models, visualizing 3D models, and generating computational models in the form of regular grids or unstructured meshes that can be used as inputs for ground-motion simulations. The UCVM framework helps researchers compare seismic velocity models and build equivalent simulation meshes from alternative velocity models. These capabilities enable researchers to evaluate the impact of alternative velocity models in ground-motion simulations and seismic hazard analysis applications

  5. Auditory velocity discrimination in the horizontal plane at very high velocities.

    Science.gov (United States)

    Frissen, Ilja; Féron, François-Xavier; Guastavino, Catherine

    2014-10-01

    We determined velocity discrimination thresholds and Weber fractions for sounds revolving around the listener at very high velocities. Sounds used were a broadband white noise and two harmonic sounds with fundamental frequencies of 330 Hz and 1760 Hz. Experiment 1 used velocities ranging between 288°/s and 720°/s in an acoustically treated room and Experiment 2 used velocities between 288°/s and 576°/s in a highly reverberant hall. A third experiment addressed potential confounds in the first two experiments. The results show that people can reliably discriminate velocity at very high velocities and that both thresholds and Weber fractions decrease as velocity increases. These results violate Weber's law but are consistent with the empirical trend observed in the literature. While thresholds for the noise and 330 Hz harmonic stimulus were similar, those for the 1760 Hz harmonic stimulus were substantially higher. There were no reliable differences in velocity discrimination between the two acoustical environments, suggesting that auditory motion perception at high velocities is robust against the effects of reverberation. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Relationship between throwing velocity, muscle power, and bar velocity during bench press in elite handball players.

    Science.gov (United States)

    Marques, Mario C; van den Tilaar, Roland; Vescovi, Jason D; Gonzalez-Badillo, Juan Jose

    2007-12-01

    The purpose of this study was to examine the relationship between ball-throwing velocity during a 3-step running throw and dynamic strength, power, and bar velocity during a concentric-only bench-press exercise in team-handball players. Fourteen elite senior male team-handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric-only bench-press test with 26, 36, and 46 kg, as well as having 1-repetition-maximum (1-RMBP) strength determined. Ball-throwing velocity was evaluated with a standard 3-step running throw using a radar gun. Ball-throwing velocity was related to the absolute load lifted during the 1-RMBP (r = .637, P = .014), peak power using 36 kg (r = .586, P = .028) and 46 kg (r = .582, P = .029), and peak bar velocity using 26 kg (r = .563, P = .036) and 36 kg (r = .625, P = .017). The results indicate that throwing velocity of elite team-handball players is related to maximal dynamic strength, peak power, and peak bar velocity. Thus, a training regimen designed to improve ball-throwing velocity in elite male team-handball players should include exercises that are aimed at increasing both strength and power in the upper body.

  7. Determination of velocity correction factors for real-time air velocity monitoring in underground mines.

    Science.gov (United States)

    Zhou, Lihong; Yuan, Liming; Thomas, Rick; Iannacchione, Anthony

    2017-12-01

    When there are installations of air velocity sensors in the mining industry for real-time airflow monitoring, a problem exists with how the monitored air velocity at a fixed location corresponds to the average air velocity, which is used to determine the volume flow rate of air in an entry with the cross-sectional area. Correction factors have been practically employed to convert a measured centerline air velocity to the average air velocity. However, studies on the recommended correction factors of the sensor-measured air velocity to the average air velocity at cross sections are still lacking. A comprehensive airflow measurement was made at the Safety Research Coal Mine, Bruceton, PA, using three measuring methods including single-point reading, moving traverse, and fixed-point traverse. The air velocity distribution at each measuring station was analyzed using an air velocity contour map generated with Surfer ® . The correction factors at each measuring station for both the centerline and the sensor location were calculated and are discussed.

  8. Indentation of aluminium foam at low velocity

    Directory of Open Access Journals (Sweden)

    Shi Xiaopeng

    2015-01-01

    Full Text Available The indentation behaviour of aluminium foams at low velocity (10 m/s ∼ 30 m/s was investigated both in experiments and numerical simulation in this paper. A flat-ended indenter was used and the force-displacement history was recorded. The Split Hopkinson Pressure bar was used to obtain the indentation velocity and forces in the dynamic experiments. Because of the low strength of the aluminium foam, PMMA bar was used, and the experimental data were corrected using Bacon's method. The energy absorption characteristics varying with impact velocity were then obtained. It was found that the energy absorption ability of aluminium foam gradually increases in the quasi-static regime and shows a significant increase at ∼10 m/s velocity. Numerical simulation was also conducted to investigate this process. A 3D Voronoi model was used and models with different relative densities were investigated as well as those with different failure strain. The indentation energy increases with both the relative density and failure strain. The analysis of the FE model implies that the significant change in energy absorption ability of aluminium foam in indentation at ∼10 m/s velocity may be caused by plastic wave effect.

  9. Surface wave velocity tracking by bisection method

    International Nuclear Information System (INIS)

    Maeda, T.

    2005-01-01

    Calculation of surface wave velocity is a classic problem dating back to the well-known Haskell's transfer matrix method, which contributes to solutions of elastic wave propagation, global subsurface structure evaluation by simulating observed earthquake group velocities, and on-site evaluation of subsurface structure by simulating phase velocity dispersion curves and/or H/V spectra obtained by micro-tremor observation. Recently inversion analysis on micro-tremor observation requires efficient method of generating many model candidates and also stable, accurate, and fast computation of dispersion curves and Raleigh wave trajectory. The original Haskell's transfer matrix method has been improved in terms of its divergence tendency mainly by the generalized transmission and reflection matrix method with formulation available for surface wave velocity; however, root finding algorithm has not been fully discussed except for the one by setting threshold to the absolute value of complex characteristic functions. Since surface wave number (reciprocal to the surface wave velocity multiplied by frequency) is a root of complex valued characteristic function, it is intractable to use general root finding algorithm. We will examine characteristic function in phase plane to construct two dimensional bisection algorithm with consideration on a layer to be evaluated and algorithm for tracking roots down along frequency axis. (author)

  10. TYPE Ia SUPERNOVA COLORS AND EJECTA VELOCITIES: HIERARCHICAL BAYESIAN REGRESSION WITH NON-GAUSSIAN DISTRIBUTIONS

    International Nuclear Information System (INIS)

    Mandel, Kaisey S.; Kirshner, Robert P.; Foley, Ryan J.

    2014-01-01

    We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II λ6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10 3 km s –1 ) –1 for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A V extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances

  11. Migration velocity analysis using pre-stack wave fields

    KAUST Repository

    Alkhalifah, Tariq Ali; Wu, Zedong

    2016-01-01

    Using both image and data domains to perform velocity inversion can help us resolve the long and short wavelength components of the velocity model, usually in that order. This translates to integrating migration velocity analysis into full waveform

  12. Velocity Controller for a Class of Vehicles

    Directory of Open Access Journals (Sweden)

    Herman Przemyslaw

    2017-02-01

    Full Text Available This paper addresses the problem of velocity tracking control for various fully-actuated robotic vehicles. The presented method, which is based on transformation of equations of motion allows one to use, in the control gain matrix, the dynamical couplings existing in the system. Consequently, the dynamics of the vehicle is incorporated into the control process what leads to fast velocity error convergence. The stability of the system under the controller is derived based on Lyapunov argument. Moreover, the robustness of the proposed controller is shown too. The general approach is valid for 6 DOF models as well as other reduced models of vehicles. Simulation results on a 6 DOF indoor airship validate the described velocity tracking methodology.

  13. Turbulent flow velocity distribution at rough walls

    International Nuclear Information System (INIS)

    Baumann, W.

    1978-08-01

    Following extensive measurements of the velocity profile in a plate channel with artificial roughness geometries specific investigations were carried out to verify the results obtained. The wall geometry used was formed by high transverse square ribs having a large pitch. The measuring position relative to the ribs was varied as a parameter thus providing a statement on the local influence of roughness ribs on the values measured. As a fundamental result it was found that the gradient of the logarithmic rough wall velocity profiles, which differs widely from the value 2.5, depends but slightly on the measuring position relative to the ribs. The gradients of the smooth wall velocity profiles deviate from 2.5 near the ribs, only. This fact can be explained by the smooth wall shear stress varying with the pitch of the ribs. (orig.) 891 GL [de

  14. 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.

  15. Critical ionisation velocity effects in astrophysical plasmas

    International Nuclear Information System (INIS)

    Raadu, M.A.

    1979-08-01

    Critical ionisation velocity effects are relevant to astrophysical situations where neutral gas moves through a magnetised plasma. The experimental significance of the critical velocity is well established and the physical basis is now becoming clear. The underlying mechanism depends on the combined effects of electron impact ionisation and electron energisation by collective plasma interactions. For low density plasmas a theory based on a circular process involving electron heating through a modified two stream instability has been developed. Several applications of critical velocity effects to astrophysical plasmas have been discussed in the literature. The importance of the effect in any particular case may be determined from a detailed consideration of energy and momentum balance, using appropriate atomic rate coefficients and taking full account of collective plasma processes. (Auth.)

  16. From Boltzmann equations to steady wall velocities

    International Nuclear Information System (INIS)

    Konstandin, Thomas; Rues, Ingo; Nardini, Germano; California Univ., Santa Barbara, CA

    2014-07-01

    By means of a relativistic microscopic approach we calculate the expansion velocity of bubbles generated during a first-order electroweak phase transition. In particular, we use the gradient expansion of the Kadanoff-Baym equations to set up the fluid system. This turns out to be equivalent to the one found in the semi-classical approach in the non-relativistic limit. Finally, by including hydrodynamic deflagration effects and solving the Higgs equations of motion in the fluid, we determine velocity and thickness of the bubble walls. Our findings are compared with phenomenological models of wall velocities. As illustrative examples, we apply these results to three theories providing first-order phase transitions with a particle content in the thermal plasma that resembles the Standard Model.

  17. A THEOREM ON CENTRAL VELOCITY DISPERSIONS

    International Nuclear Information System (INIS)

    An, Jin H.; Evans, N. Wyn

    2009-01-01

    It is shown that, if the tracer population is supported by a spherical dark halo with a core or a cusp diverging more slowly than that of a singular isothermal sphere (SIS), the logarithmic cusp slope γ of the tracers must be given exactly by γ = 2β, where β is their velocity anisotropy parameter at the center unless the same tracers are dynamically cold at the center. If the halo cusp diverges faster than that of the SIS, the velocity dispersion of the tracers must diverge at the center too. In particular, if the logarithmic halo cusp slope is larger than two, the diverging velocity dispersion also traces the behavior of the potential. The implication of our theorem on projected quantities is also discussed. We argue that our theorem should be understood as a warning against interpreting results based on simplifying assumptions such as isotropy and spherical symmetry.

  18. Velocity and Magnetic Compressions in FEL Drivers

    CERN Document Server

    Serafini, L

    2005-01-01

    We will compare merits and issues of these two techniques suitable for increasing the peak current of high brightness electron beams. The typical range of applicability is low energy for the velocity bunching and middle to high energy for magnetic compression. Velocity bunching is free from CSR effects but requires very high RF stability (time jitters), as well as a dedicated additional focusing and great cure in the beam transport: it is very well understood theoretically and numerical simulations are pretty straightforward. Several experiments of velocity bunching have been performed in the past few years: none of them, nevertheless, used a photoinjector designed and optimized for that purpose. Magnetic compression is a much more consolidated technique: CSR effects and micro-bunch instabilities are its main drawbacks. There is a large operational experience with chicanes used as magnetic compressors and their theoretical understanding is quite deep, though numerical simulations of real devices are still cha...

  19. Flocking and invariance of velocity angles.

    Science.gov (United States)

    Liu, Le; Huang, Lihong; Wu, Jianhong

    2016-04-01

    Motsch and Tadmor considered an extended Cucker-Smale model to investigate the flocking behavior of self-organized systems of interacting species. In this extended model, a cone of the vision was introduced so that outside the cone the influence of one agent on the other is lost and hence the corresponding influence function takes the value zero. This creates a problem to apply the Motsch-Tadmor and Cucker-Smale method to prove the flocking property of the system. Here, we examine the variation of the velocity angles between two arbitrary agents, and obtain a monotonicity property for the maximum cone of velocity angles. This monotonicity permits us to utilize existing arguments to show the flocking property of the system under consideration, when the initial velocity angles satisfy some minor technical constraints.

  20. Velocity dispersion profiles of clusters of galaxies

    International Nuclear Information System (INIS)

    Struble, M.F.

    1979-01-01

    Velocity dispersion as a function of radius, called sigma/sub ls/ profiles, is presented for 13 clusters of galaxies having > or =30 radial velocities from both published and unpublished lists. A list of probable new members and possible outlying members for these clusters is also given. chi 2 and Kolmogoroff--Smirnoff one-sample tests for the goodness of fit of power laws to portions of the profiles indicate two significant structures in some profiles: (1) a local minimum corresponding to the local minimum noted in surface density or surface brightness profiles, and (2) a decrease in sigma/sub ls/ toward the cores. Both of these features are discussed in terms of a comparison with Wielen's N-body simulations. The sigma/sub ls/ profiles are placed in a new classification scheme which lends itself to interpreting clusters in a dynamical age sequence. The velocity field of galaxies at large distances from cluster centers is also discussed

  1. Radial velocity observations of VB10

    Science.gov (United States)

    Deshpande, R.; Martin, E.; Zapatero Osorio, M. R.; Del Burgo, C.; Rodler, F.; Montgomery, M. M.

    2011-07-01

    VB 10 is the smallest star known to harbor a planet according to the recent astrometric study of Pravdo & Shaklan [1]. Here we present near-infrared (J-band) radial velocity of VB 10 performed from high resolution (R~20,000) spectroscopy (NIRSPEC/KECK II). Our results [2] suggest radial velocity variability with amplitude of ~1 km/s, a result that is consistent with the presence of a massive planet companion around VB10 as found via long-term astrometric monitoring of the star by Pravdo & Shaklan. Employing an entirely different technique we verify the results of Pravdo & Shaklan.

  2. Tailoring group velocity by topology optimization

    DEFF Research Database (Denmark)

    Stainko, Roman; Sigmund, Ole

    2007-01-01

    The paper describes a systematic method for the tailoring of dispersion properties of slab-based photonic crystal waveguides. The method is based on the topology optimization method which consists in repeated finite element frequency domain analyses. The goal of the optimization process is to come...... up with slow light, zero group velocity dispersion photonic waveguides or photonic waveguides with tailored dispersion properties for dispersion compensation purposes. An example concerning the design of a wide bandwidth, constant low group velocity waveguide demonstrate the e±ciency of the method....

  3. STARE velocities: 2. Evening westward electron flow

    Directory of Open Access Journals (Sweden)

    M. Uspensky

    2004-04-01

    Full Text Available Four evening events and one morning event of joint EISCAT/STARE observations during ~22h are considered and the differences between observed STARE line-of-sight (l-o-s velocities and EISCAT electron drift velocities projected onto the STARE beams are studied. We demonstrate that the double-pulse technique, which is currently in use in the STARE routine data handling, typically underestimates the true phase velocity as inferred from the multi-pulse STARE data. We show that the STARE velocities are persistently smaller (1.5–2 times than the EISCAT velocities, even for the multi-pulse data. The effect seems to be more pronounced in the evening sector when the Finland radar observes at large flow angles. We evaluate the performance of the ion-acoustic approach (IAA, Nielsen and Schlegel, 1985 and the off-orthogonal fluid approach (OOFA, Uspensky et al., 2003 techniques to predict the true electron drift velocity for the base event of 12 February 1999. The IAA technique predicts the convection reasonably well for enhanced flows of >~1000m/s, but not so well for slower ones. By considering the EISCAT N(h profiles, we derive the effective aspect angle and effective altitude of backscatter, and use this information for application of the OOFA technique. We demonstrate that the OOFA predictions for the base event are superior over the IAA predictions and thus, we confirm that OOFA predicts the electron velocities reasonably well in the evening sector, in addition to the morning sector, as concluded by Uspensky et al. (2003. To check how "robust" the OOFA model is and how successful it is for convection estimates without the EISCAT support, we analysed three additional evening events and one additional morning event for which information on N(h profiles was intentionally ignored. By accepting the mean STARE/EISCAT velocity ratio of 0.55 and the mean azimuth rotation of 9° (derived for the basic event, we show that the OOFA performs

  4. Surface Velocities and Hydrology at Engabreen

    DEFF Research Database (Denmark)

    Messerli, Alexandra

    complicates comparisons with other surface-oriented glaciohydrological studies. One major aim of this thesis is to provide a longer record of surface velocity, enabling a more complete understanding of the glacial hydro-mechanical relationship at Engabreen. In order to extend the velocity dataset here, a time...... the lower tongue of Engabreen are analysed in detail alongside the hydro-meteorological time-series. The higher temporal resolution of the GPS allows the effect of short-term hydrological forcings on ice flow to be assessed. Two key events: the spring-speed up event (P1a) and a short-term rain induced event...

  5. Metastable structure formation during high velocity grinding

    International Nuclear Information System (INIS)

    Samarin, A.N.; Klyuev, M.M.

    1984-01-01

    Metastable structures in surface layers of samples are; investigated during force high-velocity abrasive grinding. Samples of martensitic (40Kh13), austenitic (12Kh18N10T), ferritic (05Kh23Yu5) steels and some alloys, in particular KhN77TYuR (EhI437B), were grinded for one pass at treatment depth from 0.17 up to 2.6 mm. It is established that processes of homogenizing, recrystallization and coagulation are; developed during force high-velocity grinding along with polymorphic transformations in the zone of thermomechanical effect, that leads to changes of physical and mechanical properties of the surface

  6. On the velocity distributions of granular gases

    International Nuclear Information System (INIS)

    Polito, A.M.M.; Rocha Filho, T.M.; Figueiredo, A.

    2009-01-01

    We present a new approach to determine velocity distributions in granular gases to improve the Sonine polynomial expansion of the velocity distribution function, at higher inelasticities, for the homogeneous cooling regime of inelastic hard spheres. The perturbative consistency is recovered using a new set of dynamical variables based on the characteristic function and we illustrate our approach by computing the first four Sonine coefficients for moderate and high inelasticities. The analytical coefficients are compared with molecular dynamics simulations results and with a previous approach by Huthmann et al.

  7. Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G; Geenen, H; Giffels, M; Haj Ahmad, W; Hermanns, T; Heydhausen, D; Kalinin, S; Kress, T; Linn, A; Nowack, A; Perchalla, L; Poettgens, M; Pooth, O; Sauerland, P; Stahl, A; Tornier, D; Zoeller, M H; Aldaya Martin, M; Behrens, U; Borras, K; Campbell, A; Castro, E; Dammann, D; Eckerlin, G; Flossdorf, A; Flucke, G; Geiser, A; Hatton, D; Hauk, J; Jung, H; Kasemann, M; Katkov, I; Kleinwort, C; Kluge, H; Knutsson, A; Kuznetsova, E; Lange, W; Lohmann, W; Mankel, R; Marienfeld, M; Meyer, A B; Miglioranzi, S; Mnich, J; Ohlerich, M; Olzem, J; Parenti, A; Rosemann, C; Schmidt, R; Schoerner-Sadenius, T; Volyanskyy, D; Wissing, C; Zeuner, W D; Autermann, C; Bechtel, F; Draeger, J; Eckstein, D; Gebbert, U; Kaschube, K; Kaussen, G; Klanner, R; Mura, B; Naumann-Emme, S; Nowak, F; Pein, U; Sander, C; Schleper, P; Schum, T; Stadie, H; Steinbrück, G; Thomsen, J; Wolf, R; Bauer, J; Blüm, P; Buege, V; Cakir, A; Chwalek, T; De Boer, W; Dierlamm, A; Dirkes, G; Feindt, M; Felzmann, U; Frey, M; Furgeri, A; Gruschke, J; Hackstein, C; Hartmann, F; Heier, S; Heinrich, M; Held, H; Hirschbuehl, D; Hoffmann, K H; Honc, S; Jung, C; Kuhr, T; Liamsuwan, T; Martschei, D; Mueller, S; Müller, Th; Neuland, M B; Niegel, M; Oberst, O; Oehler, A; Ott, J; Peiffer, T; Piparo, D; Quast, G; Rabbertz, K; Ratnikov, F; Ratnikova, N; Renz, M; Saout, C; Sartisohn, G; Scheurer, A; Schieferdecker, P; Schilling, F P; Schott, G; Simonis, H J; Stober, F M; Sturm, P; Troendle, D; Trunov, A; Wagner, W; Wagner-Kuhr, J; Zeise, M; Zhukov, V; Ziebarth, E B; Daskalakis, G; Geralis, T; Karafasoulis, K; Kyriakis, A; Loukas, D; Markou, A; Markou, C; Mavrommatis, C; Petrakou, E; Zachariadou, A; Gouskos, L; Katsas, P; Panagiotou, A; Evangelou, I; Kokkas, P; Manthos, N; Papadopoulos, I; Patras, V; Triantis, F A; Bencze, G; Boldizsar, L; Debreczeni, G; Hajdu, C; Hernath, S; Hidas, P; Horvath, D; Krajczar, K; Laszlo, A; Patay, G; Sikler, F; Toth, N; Vesztergombi, G; Beni, N; Christian, G; Imrek, J; Molnar, J; Novak, D; Palinkas, J; Szekely, G; Szillasi, Z; Tokesi, K; Veszpremi, V; Kapusi, A; Marian, G; Raics, P; Szabo, Z; Trocsanyi, Z L; Ujvari, B; Zilizi, G; Bansal, S; Bawa, H S; Beri, S B; Bhatnagar, V; Jindal, M; Kaur, M; Kaur, R; Kohli, J M; Mehta, M Z; Nishu, N; Saini, L K; Sharma, A; Singh, A; Singh, J B; Singh, S P; Ahuja, S; Arora, S; Bhattacharya, S; Chauhan, S; Choudhary, B C; Gupta, P; Jain, S; Jha, M; Kumar, A; Ranjan, K; Shivpuri, R K; Srivastava, A K; Choudhury, R K; Dutta, D; Kailas, S; Kataria, S K; Mohanty, A K; Pant, L M; Shukla, P; Topkar, A; Aziz, T; Guchait, M; Gurtu, A; Maity, M; Majumder, D; Majumder, G; Mazumdar, K; Nayak, A; Saha, A; Sudhakar, K; Banerjee, S; Dugad, S; Mondal, N K; Arfaei, H; Bakhshiansohi, H; Fahim, A; Jafari, A; Mohammadi Najafabadi, M; Moshaii, A; Paktinat Mehdiabadi, S; Rouhani, S; Safarzadeh, B; Zeinali, M; Felcini, M; Abbrescia, M; Barbone, L; Chiumarulo, F; Clemente, A; Colaleo, A; Creanza, D; Cuscela, G; De Filippis, N; De Palma, M; De Robertis, G; Donvito, G; Fedele, F; Fiore, L; Franco, M; Iaselli, G; Lacalamita, N; Loddo, F; Lusito, L; Maggi, G; Maggi, M; Manna, N; Marangelli, B; My, S; Natali, S; Nuzzo, S; Papagni, G; Piccolomo, S; Pierro, G A; Pinto, C; Pompili, A; Pugliese, G; Rajan, R; Ranieri, A; Romano, F; Roselli, G; Selvaggi, G; Shinde, Y; Silvestris, L; Tupputi, S; Zito, G; Abbiendi, G; Bacchi, W; Benvenuti, A C; Boldini, M; Bonacorsi, D; Braibant-Giacomelli, S; Cafaro, V D; Caiazza, S S; Capiluppi, P; Castro, A; Cavallo, F R; Codispoti, G; Cuffiani, M; D'Antone, I; Dallavalle, G M; Fabbri, F; Fanfani, A; Fasanella, D; Giacomelli, P; Giordano, V; Giunta, M; Grandi, C; Guerzoni, M; Marcellini, S; Masetti, G; Montanari, A; Navarria, F L; Odorici, F; Pellegrini, G; Perrotta, A; Rossi, A M; Rovelli, T; Siroli, G; Torromeo, G; Travaglini, R; Albergo, S; Costa, S; Potenza, R; Tricomi, A; Tuve, C; Barbagli, G; Broccolo, G; Ciulli, V; Civinini, C; D'Alessandro, R; Focardi, E; Frosali, S; Gallo, E; Genta, C; Landi, G; Lenzi, P; Meschini, M; Paoletti, S; Sguazzoni, G; Tropiano, A; Benussi, L; Bertani, M; Bianco, S; Colafranceschi, S; Colonna, D; Fabbri, F; Giardoni, M; Passamonti, L; Piccolo, D; Pierluigi, D; Ponzio, B; Russo, A; Fabbricatore, P; Musenich, R; Benaglia, A; Calloni, M; Cerati, G B; D'Angelo, P; De Guio, F; Farina, F M; Ghezzi, A; Govoni, P; Malberti, M; Malvezzi, S; Martelli, A; Menasce, D; Miccio, V; Moroni, L; Negri, P; Paganoni, M; Pedrini, D; Pullia, A; Ragazzi, S; Redaelli, N; Sala, S; Salerno, R; Tabarelli de Fatis, T; Tancini, V; Taroni, S; Buontempo, S; Cavallo, N; Cimmino, A; De Gruttola, M; Fabozzi, F; Iorio, A O M; Lista, L; Lomidze, D; Noli, P; Paolucci, P; Sciacca, C; Azzi, P; Bacchetta, N; Barcellan, L; Bellan, P; Bellato, M; Benettoni, M; Biasotto, M; Bisello, D; Borsato, E; Branca, A; Carlin, R; Castellani, L; Checchia, P; Conti, E; Dal Corso, F; De Mattia, M; Dorigo, T; Dosselli, U; Fanzago, F; Gasparini, F; Gasparini, U; Giubilato, P; Gonella, F; Gresele, A; Gulmini, M; Kaminskiy, A; Lacaprara, S; Lazzizzera, I; Margoni, M; Maron, G; Mattiazzo, S; Mazzucato, M; Meneghelli, M; Meneguzzo, A T; Michelotto, M; Montecassiano, F; Nespolo, M; Passaseo, M; Pegoraro, M; Perrozzi, L; Pozzobon, N; Ronchese, P; Simonetto, F; Toniolo, N; Torassa, E; Tosi, M; Triossi, A; Vanini, S; Ventura, S; Zotto, P; Zumerle, G; Baesso, P; Berzano, U; Bricola, S; Necchi, M M; Pagano, D; Ratti, S P; Riccardi, C; Torre, P; Vicini, A; Vitulo, P; Viviani, C; Aisa, D; Aisa, S; Babucci, E; Biasini, M; Bilei, G M; Caponeri, B; Checcucci, B; Dinu, N; Fanò, L; Farnesini, L; Lariccia, P; Lucaroni, A; Mantovani, G; Nappi, A; Piluso, A; Postolache, V; Santocchia, A; Servoli, L; Tonoiu, D; Vedaee, A; Volpe, R; Azzurri, P; Bagliesi, G; Bernardini, J; Berretta, L; Boccali, T; Bocci, A; Borrello, L; Bosi, F; Calzolari, F; Castaldi, R; Dell'Orso, R; Fiori, F; Foà, L; Gennai, S; Giassi, A; Kraan, A; Ligabue, F; Lomtadze, T; Mariani, F; Martini, L; Massa, M; Messineo, A; Moggi, A; Palla, F; Palmonari, F; Petragnani, G; Petrucciani, G; Raffaelli, F; Sarkar, S; Segneri, G; Serban, A T; Spagnolo, P; Tenchini, R; Tolaini, S; Tonelli, G; Venturi, A; Verdini, P G; Baccaro, S; Barone, L; Bartoloni, A; Cavallari, F; Dafinei, I; Del Re, D; Di Marco, E; Diemoz, M; Franci, D; Longo, E; Organtini, G; Palma, A; Pandolfi, F; Paramatti, R; Pellegrino, F; Rahatlou, S; Rovelli, C; Alampi, G; Amapane, N; Arcidiacono, R; Argiro, S; Arneodo, M; Biino, C; Borgia, M A; Botta, C; Cartiglia, N; Castello, R; Cerminara, G; Costa, M; Dattola, D; Dellacasa, G; Demaria, N; Dughera, G; Dumitrache, F; Graziano, A; Mariotti, C; Marone, M; Maselli, S; Migliore, E; Mila, G; Monaco, V; Musich, M; Nervo, M; Obertino, M M; Oggero, S; Panero, R; Pastrone, N; Pelliccioni, M; Romero, A; Ruspa, M; Sacchi, R; Solano, A; Staiano, A; Trapani, P P; Trocino, D; Vilela Pereira, A; Visca, L; Zampieri, A; Ambroglini, F; Belforte, S; Cossutti, F; Della Ricca, G; Gobbo, B; Penzo, A; Chang, S; Chung, J; Kim, D H; Kim, G N; Kong, D J; Park, H; Son, D C; Bahk, S Y; Song, S; Jung, S Y; Hong, B; Kim, H; Kim, J H; Lee, K S; Moon, D H; Park, S K; Rhee, H B; Sim, K S; Kim, J; Choi, M; Hahn, G; Park, I C; Choi, S; Choi, Y; Goh, J; Jeong, H; Kim, T J; Lee, J; Lee, S; Janulis, M; Martisiute, D; Petrov, P; Sabonis, T; Castilla Valdez, H; Sánchez Hernández, A; Carrillo Moreno, S; Morelos Pineda, A; Allfrey, P; Gray, R N C; Krofcheck, D; Bernardino Rodrigues, N; Butler, P H; Signal, T; Williams, J C; Ahmad, M; Ahmed, I; Ahmed, W; Asghar, M I; Awan, M I M; Hoorani, H R; Hussain, I; Khan, W A; Khurshid, T; Muhammad, S; Qazi, S; Shahzad, H; Cwiok, M; Dabrowski, R; Dominik, W; Doroba, K; Konecki, M; Krolikowski, J; Pozniak, K; Romaniuk, Ryszard; Zabolotny, W; Zych, P; Frueboes, T; Gokieli, R; Goscilo, L; Górski, M; Kazana, M; Nawrocki, K; Szleper, M; Wrochna, G; Zalewski, P; Almeida, N; Antunes Pedro, L; Bargassa, P; David, A; Faccioli, P; Ferreira Parracho, P G; Freitas Ferreira, M; Gallinaro, M; Guerra Jordao, M; Martins, P; Mini, G; Musella, P; Pela, J; Raposo, L; Ribeiro, P Q; Sampaio, S; Seixas, J; Silva, J; Silva, P; Soares, D; Sousa, M; Varela, J; Wöhri, H K; Altsybeev, I; Belotelov, I; Bunin, P; Ershov, Y; Filozova, I; Finger, M; Finger, M., Jr.; Golunov, A; Golutvin, I; Gorbounov, N; Kalagin, V; Kamenev, A; Karjavin, V; Konoplyanikov, V; Korenkov, V; Kozlov, G; Kurenkov, A; Lanev, A; Makankin, A; Mitsyn, V V; Moisenz, P; Nikonov, E; Oleynik, D; Palichik, V; Perelygin, V; Petrosyan, A; Semenov, R; Shmatov, S; Smirnov, V; Smolin, D; Tikhonenko, E; Vasil'ev, S; Vishnevskiy, A; Volodko, A; Zarubin, A; Zhiltsov, V; Bondar, N; Chtchipounov, L; Denisov, A; Gavrikov, Y; Gavrilov, G; Golovtsov, V; Ivanov, Y; Kim, V; Kozlov, V; Levchenko, P; Obrant, G; Orishchin, E; Petrunin, A; Shcheglov, Y; Shchetkovskiy, A; Sknar, V; Smirnov, I; Sulimov, V; Tarakanov, V; Uvarov, L; Vavilov, S; Velichko, G; Volkov, S; Vorobyev, A; Andreev, Yu; Anisimov, A; Antipov, P; Dermenev, A; Gninenko, S; Golubev, N; Kirsanov, M; Krasnikov, N; Matveev, V; Pashenkov, A; Postoev, V E; Solovey, A; Toropin, A; Troitsky, S; Baud, A; Epshteyn, V; Gavrilov, V; Ilina, N; Kaftanov, V; Kolosov, V; Kossov, M; Krokhotin, A; Kuleshov, S; Oulianov, A; Safronov, G; Semenov, S; Shreyber, I; Stolin, V; Vlasov, E; Zhokin, A; Boos, E; Dubinin, M; Dudko, L; Ershov, A; Gribushin, A; Klyukhin, V; Kodolova, O; Lokhtin, I; Petrushanko, S; Sarycheva, L; Savrin, V; Snigirev, A; Vardanyan, I; Dremin, I; Kirakosyan, M; Konovalova, N; Rusakov, S V; Vinogradov, A; Akimenko, S; Artamonov, A; Azhgirey, I; Bitioukov, S; Burtovoy, V; Grishin, V; Kachanov, V; Konstantinov, D; Krychkine, V; Levine, A; Lobov, I; Lukanin, V; Mel'nik, Y; Petrov, V; Ryutin, R; Slabospitsky, S; Sobol, A; Sytine, A; Tourtchanovitch, L; Troshin, S; Tyurin, N; Uzunian, A; Volkov, A; Adzic, P; Djordjevic, M; Jovanovic, D; Krpic, D; Maletic, D; Puzovic, J; Smiljkovic, N; Aguilar-Benitez, M; Alberdi, J; Alcaraz Maestre, J; Arce, P; Barcala, J M; Battilana, C; Burgos Lazaro, C; Caballero Bejar, J; Calvo, E; Cardenas Montes, M; Cepeda, M; Cerrada, M; Chamizo Llatas, M; Clemente, F; Colino, N; Daniel, M; De La Cruz, B; Delgado Peris, A; Diez Pardos, C; Fernandez Bedoya, C; Fernández Ramos, J P; Ferrando, A; Flix, J; Fouz, M C; Garcia-Abia, P; Garcia-Bonilla, A C; Gonzalez Lopez, O; Goy Lopez, S; Hernandez, J M; Josa, M I; Marin, J; Merino, G; Molina, J; Molinero, A; Navarrete, J J; Oller, J C; Puerta Pelayo, J; Romero, L; Santaolalla, J; Villanueva Munoz, C; Willmott, C; Yuste, C; Albajar, C; Blanco Otano, M; de Trocóniz, J F; Garcia Raboso, A; Lopez Berengueres, J O; Cuevas, J; Fernandez Menendez, J; Gonzalez Caballero, I; Lloret Iglesias, L; Naves Sordo, H; Vizan Garcia, J M; Cabrillo, I J; Calderon, A; Chuang, S H; Diaz Merino, I; Diez Gonzalez, C; Duarte Campderros, J; Fernandez, M; Gomez, G; Gonzalez Sanchez, J; Gonzalez Suarez, R; Jorda, C; Lobelle Pardo, P; Lopez Virto, A; Marco, J; Marco, R; Martinez Rivero, C; Martinez Ruiz del Arbol, P; Matorras, F; Rodrigo, T; Ruiz Jimeno, A; Scodellaro, L; Sobron Sanudo, M; Vila, I; Vilar Cortabitarte, R; Abbaneo, D; Albert, E; Alidra, M; Ashby, S; Auffray, E; Baechler, J; Baillon, P; Ball, A H; Bally, S L; Barney, D; Beaudette, F; Bellan, R; Benedetti, D; Benelli, G; Bernet, C; Bloch, P; Bolognesi, S; Bona, M; Bos, J; Bourgeois, N; Bourrel, T; Breuker, H; Bunkowski, K; Campi, D; Camporesi, T; Cano, E; Cattai, A; Chatelain, J P; Chauvey, M; Christiansen, T; Coarasa Perez, J A; Conde Garcia, A; Covarelli, R; Curé, B; De Roeck, A; Delachenal, V; Deyrail, D; Di Vincenzo, S; Dos Santos, S; Dupont, T; Edera, L M; Elliott-Peisert, A; Eppard, M; Favre, M; Frank, N; Funk, W; Gaddi, A; Gastal, M; Gateau, M; Gerwig, H; Gigi, D; Gill, K; Giordano, D; Girod, J P; Glege, F; Gomez-Reino Garrido, R; Goudard, R; Gowdy, S; Guida, R; Guiducci, L; Gutleber, J; Hansen, M; Hartl, C; Harvey, J; Hegner, B; Hoffmann, H F; Holzner, A; Honma, A; Huhtinen, M; Innocente, V; Janot, P; Le Godec, G; Lecoq, P; Leonidopoulos, C; Loos, R; Lourenço, C; Lyonnet, A; Macpherson, A; Magini, N; Maillefaud, J D; Maire, G; Mäki, T; Malgeri, L; Mannelli, M; Masetti, L; Meijers, F; Meridiani, P; Mersi, S; Meschi, E; Meynet Cordonnier, A; Moser, R; Mulders, M; Mulon, J; Noy, M; Oh, A; Olesen, G; Onnela, A; Orimoto, T; Orsini, L; Perez, E; Perinic, G; Pernot, J F; Petagna, P; Petiot, P; Petrilli, A; Pfeiffer, A; Pierini, M; Pimiä, M; Pintus, R; Pirollet, B; Postema, H; Racz, A; Ravat, S; Rew, S B; Rodrigues Antunes, J; Rolandi, G; Rovere, M; Ryjov, V; Sakulin, H; Samyn, D; Sauce, H; Schäfer, C; Schlatter, W D; Schröder, M; Schwick, C; Sciaba, A; Segoni, I; Sharma, A; Siegrist, N; Siegrist, P; Sinanis, N; Sobrier, T; Sphicas, P; Spiga, D; Spiropulu, M; Stöckli, F; Traczyk, P; Tropea, P; Troska, J; Tsirou, A; Veillet, L; Veres, G I; Voutilainen, M; Wertelaers, P; Zanetti, M; Bertl, W; Deiters, K; Erdmann, W; Gabathuler, K; Horisberger, R; Ingram, Q; Kaestli, H C; König, S; Kotlinski, D; Langenegger, U; Meier, F; Renker, D; Rohe, T; Sibille, J; Starodumov, A; Betev, B; Caminada, L; Chen, Z; Cittolin, S; Da Silva Di Calafiori, D R; Dambach, S; Dissertori, G; Dittmar, M; Eggel, C; Eugster, J; Faber, G; Freudenreich, K; Grab, C; Hervé, A; Hintz, W; Lecomte, P; Luckey, P D; Lustermann, W; Marchica, C; Milenovic, P; Moortgat, F; Nardulli, A; Nessi-Tedaldi, F; Pape, L; Pauss, F; Punz, T; Rizzi, A; Ronga, F J; Sala, L; Sanchez, A K; Sawley, M C; Sordini, V; Stieger, B; Tauscher, L; Thea, A; Theofilatos, K; Treille, D; Trüb, P; Weber, M; Wehrli, L; Weng, J; Zelepoukine, S; Amsler, C; Chiochia, V; De Visscher, S; Regenfus, C; Robmann, P; Rommerskirchen, T; Schmidt, A; Tsirigkas, D; Wilke, L; Chang, Y H; Chen, E A; Chen, W T; Go, A; Kuo, C M; Li, S W; Lin, W; Bartalini, P; Chang, P; Chao, Y; Chen, K F; Hou, W S; Hsiung, Y; Lei, Y J; Lin, S W; Lu, R S; Schümann, J; Shiu, J G; Tzeng, Y M; Ueno, K; Velikzhanin, Y; Wang, C C; Wang, M; Adiguzel, A; Ayhan, A; Azman Gokce, A; Bakirci, M N; Cerci, S; Dumanoglu, I; Eskut, E; Girgis, S; Gurpinar, E; Hos, I; Karaman, T; Kayis Topaksu, A; Kurt, P; Önengüt, G; Önengüt Gökbulut, G; Ozdemir, K; Ozturk, S; Polatöz, A; Sogut, K; Tali, B; Topakli, H; Uzun, D; Vergili, L N; Vergili, M; Akin, I V; Aliev, T; Bilmis, S; Deniz, M; Gamsizkan, H; Guler, A M; Öcalan, K; Serin, M; Sever, R; Surat, U E; Zeyrek, M; Deliomeroglu, M; Demir, D; Gülmez, E; Halu, A; Isildak, B; Kaya, M; Kaya, O; Ozkorucuklu, S; Sonmez, N; Levchuk, L; Lukyanenko, S; Soroka, D; Zub, S; Bostock, F; Brooke, J J; Cheng, T L; Cussans, D; Frazier, R; Goldstein, J; Grant, N; Hansen, M; Heath, G P; Heath, H F; Hill, C; Huckvale, B; Jackson, J; Mackay, C K; Metson, S; Newbold, D M; Nirunpong, K; Smith, V J; Velthuis, J; Walton, R; Bell, K W; Brew, C; Brown, R M; Camanzi, B; Cockerill, D J A; Coughlan, J A; Geddes, N I; Harder, K; Harper, S; Kennedy, B W; Murray, P; Shepherd-Themistocleous, C H; Tomalin, I R; Williams, J H; Womersley, W J; Worm, S D; Bainbridge, R; Ball, G; Ballin, J; Beuselinck, R; Buchmuller, O; Colling, D; Cripps, N; Davies, G; Della Negra, M; Foudas, C; Fulcher, J; Futyan, D; Hall, G; Hays, J; Iles, G; Karapostoli, G; MacEvoy, B C; Magnan, A M; Marrouche, J; Nash, J; Nikitenko, A; Papageorgiou, A; Pesaresi, M; Petridis, K; Pioppi, M; Raymond, D M; Rompotis, N; Rose, A; Ryan, M J; Seez, C; Sharp, P; Sidiropoulos, G; Stettler, M; Stoye, M; Takahashi, M; Tapper, A; Timlin, C; Tourneur, S; Vazquez Acosta, M; Virdee, T; Wakefield, S; Wardrope, D; Whyntie, T; Wingham, M; Cole, J E; Goitom, I; Hobson, P R; Khan, A; Kyberd, P; Leslie, D; Munro, C; Reid, I D; Siamitros, C; Taylor, R; Teodorescu, L; Yaselli, I; Bose, T; Carleton, M; Hazen, E; Heering, A H; Heister, A; John, J St; Lawson, P; Lazic, D; Osborne, D; Rohlf, J; Sulak, L; Wu, S; Andrea, J; Avetisyan, A; Bhattacharya, S; Chou, J P; Cutts, D; Esen, S; Kukartsev, G; Landsberg, G; Narain, M; Nguyen, D; Speer, T; Tsang, K V; Breedon, R; Calderon De La Barca Sanchez, M; Case, M; Cebra, D; Chertok, M; Conway, J; Cox, P T; Dolen, J; Erbacher, R; Friis, E; Ko, W; Kopecky, A; Lander, R; Lister, A; Liu, H; Maruyama, S; Miceli, T; Nikolic, M; Pellett, D; Robles, J; Searle, M; Smith, J; Squires, M; Stilley, J; Tripathi, M; Vasquez Sierra, R; Veelken, C; Andreev, V; Arisaka, K; Cline, D; Cousins, R; Erhan, S; Hauser, J; Ignatenko, M; Jarvis, C; Mumford, J; Plager, C; Rakness, G; Schlein, P; Tucker, J; Valuev, V; Wallny, R; Yang, X; Babb, J; Bose, M; Chandra, A; Clare, R; Ellison, J A; Gary, J W; Hanson, G; Jeng, G Y; Kao, S C; Liu, F; Liu, H; Luthra, A; Nguyen, H; Pasztor, G; Satpathy, A; Shen, B C; Stringer, R; Sturdy, J; Sytnik, V; Wilken, R; Wimpenny, S; Branson, J G; Dusinberre, E; Evans, D; Golf, F; Kelley, R; Lebourgeois, M; Letts, J; Lipeles, E; Mangano, B; Muelmenstaedt, J; Norman, M; Padhi, S; Petrucci, A; Pi, H; Pieri, M; Ranieri, R; Sani, M; Sharma, V; Simon, S; Würthwein, F; Yagil, A; Campagnari, C; D'Alfonso, M; Danielson, T; Garberson, J; Incandela, J; Justus, C; Kalavase, P; Koay, S A; Kovalskyi, D; Krutelyov, V; Lamb, J; Lowette, S; Pavlunin, V; Rebassoo, F; Ribnik, J; Richman, J; Rossin, R; Stuart, D; To, W; Vlimant, J R; Witherell, M; Apresyan, A; Bornheim, A; Bunn, J; Chiorboli, M; Gataullin, M; Kcira, D; Litvine, V; Ma, Y; Newman, H B; Rogan, C; Timciuc, V; Veverka, J; Wilkinson, R; Yang, Y; Zhang, L; Zhu, K; Zhu, R Y; Akgun, B; Carroll, R; Ferguson, T; Jang, D W; Jun, S Y; Paulini, M; Russ, J; Terentyev, N; Vogel, H; Vorobiev, I; Cumalat, J P; Dinardo, M E; Drell, B R; Ford, W T; Heyburn, B; Luiggi Lopez, E; Nauenberg, U; Stenson, K; Ulmer, K; Wagner, S R; Zang, S L; Agostino, L; Alexander, J; Blekman, F; Cassel, D; Chatterjee, A; Das, S; Gibbons, L K; Heltsley, B; Hopkins, W; Khukhunaishvili, A; Kreis, B; Kuznetsov, V; Patterson, J R; Puigh, D; Ryd, A; Shi, X; Stroiney, S; Sun, W; Teo, W D; Thom, J; Vaughan, J; Weng, Y; Wittich, P; Beetz, C P; Cirino, G; Sanzeni, C; Winn, D; Abdullin, S; Afaq, M A; Albrow, M; Ananthan, B; Apollinari, G; Atac, M; Badgett, W; Bagby, L; Bakken, J A; Baldin, B; Banerjee, S; Banicz, K; Bauerdick, L A T; Beretvas, A; Berryhill, J; Bhat, P C; Biery, K; Binkley, M; Bloch, I; Borcherding, F; Brett, A M; Burkett, K; Butler, J N; Chetluru, V; Cheung, H W K; Chlebana, F; Churin, I; Cihangir, S; Crawford, M; Dagenhart, W; Demarteau, M; Derylo, G; Dykstra, D; Eartly, D P; Elias, J E; Elvira, V D; Evans, D; Feng, L; Fischler, M; Fisk, I; Foulkes, S; Freeman, J; Gartung, P; Gottschalk, E; Grassi, T; Green, D; Guo, Y; Gutsche, O; Hahn, A; Hanlon, J; Harris, R M; Holzman, B; Howell, J; Hufnagel, D; James, E; Jensen, H; Johnson, M; Jones, C D; Joshi, U; Juska, E; Kaiser, J; Klima, B; Kossiakov, S; Kousouris, K; Kwan, S; Lei, C M; Limon, P; Lopez Perez, J A; Los, S; Lueking, L; Lukhanin, G; Lusin, S; Lykken, J; Maeshima, K; Marraffino, J M; Mason, D; McBride, P; Miao, T; Mishra, K; Moccia, S; Mommsen, R; Mrenna, S; Muhammad, A S; Newman-Holmes, C; Noeding, C; O'Dell, V; Prokofyev, O; Rivera, R; Rivetta, C H; Ronzhin, A; Rossman, P; Ryu, S; Sekhri, V; Sexton-Kennedy, E; Sfiligoi, I; Sharma, S; Shaw, T M; Shpakov, D; Skup, E; Smith, R P; Soha, A; Spalding, W J; Spiegel, L; Suzuki, I; Tan, P; Tanenbaum, W; Tkaczyk, S; Trentadue, R; Uplegger, L; Vaandering, E W; Vidal, R; Whitmore, J; Wicklund, E; Wu, W; Yarba, J; Yumiceva, F; Yun, J C; Acosta, D; Avery, P; Barashko, V; Bourilkov, D; Chen, M; Di Giovanni, G P; Dobur, D; Drozdetskiy, A; Field, R D; Fu, Y; Furic, I K; Gartner, J; Holmes, D; Kim, B; Klimenko, S; Konigsberg, J; Korytov, A; Kotov, K; Kropivnitskaya, A; Kypreos, T; Madorsky, A; Matchev, K; Mitselmakher, G; Pakhotin, Y; Piedra Gomez, J; Prescott, C; Rapsevicius, V; Remington, R; Schmitt, M; Scurlock, B; Wang, D; Yelton, J; Ceron, C; Gaultney, V; Kramer, L; Lebolo, L M; Linn, S; Markowitz, P; Martinez, G; Rodriguez, J L; Adams, T; Askew, A; Baer, H; Bertoldi, M; Chen, J; Dharmaratna, W G D; Gleyzer, S V; Haas, J; Hagopian, S; Hagopian, V; Jenkins, M; Johnson, K F; Prettner, E; Prosper, H; Sekmen, S; Baarmand, M M; Guragain, S; Hohlmann, M; Kalakhety, H; Mermerkaya, H; Ralich, R; Vodopiyanov, I; Abelev, B; Adams, M R; Anghel, I M; Apanasevich, L; Bazterra, V E; Betts, R R; Callner, J; Castro, M A; Cavanaugh, R; Dragoiu, C; Garcia-Solis, E J; Gerber, C E; Hofman, D J; Khalatian, S; Mironov, C; Shabalina, E; Smoron, A; Varelas, N; Akgun, U; Albayrak, E A; Ayan, A S; Bilki, B; Briggs, R; Cankocak, K; Chung, K; Clarida, W; Debbins, P; Duru, F; Ingram, F D; Lae, C K; McCliment, E; Merlo, J P; Mestvirishvili, A; Miller, M J; Moeller, A; Nachtman, J; Newsom, C R; Norbeck, E; Olson, J; Onel, Y; Ozok, F; Parsons, J; Schmidt, I; Sen, S; Wetzel, J; Yetkin, T; Yi, K; Barnett, B A; Blumenfeld, B; Bonato, A; Chien, C Y; Fehling, D; Giurgiu, G; Gritsan, A V; Guo, Z J; Maksimovic, P; Rappoccio, S; Swartz, M; Tran, N V; Zhang, Y; Baringer, P; Bean, A; Grachov, O; Murray, M; Radicci, V; Sanders, S; Wood, J S; Zhukova, V; Bandurin, D; Bolton, T; Kaadze, K; Liu, A; Maravin, Y; Onoprienko, D; Svintradze, I; Wan, Z; Gronberg, J; Hollar, J; Lange, D; Wright, D; Baden, D; Bard, R; Boutemeur, M; Eno, S C; Ferencek, D; Hadley, N J; Kellogg, R G; Kirn, M; Kunori, S; Rossato, K; Rumerio, P; Santanastasio, F; Skuja, A; Temple, J; Tonjes, M B; Tonwar, S C; Toole, T; Twedt, E; Alver, B; Bauer, G; Bendavid, J; Busza, W; Butz, E; Cali, I A; Chan, M; D'Enterria, D; Everaerts, P; Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of cosmic muons. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.

  8. Effect of movement velocity on the relationship between training load and the number of repetitions of bench press.

    Science.gov (United States)

    Sakamoto, Akihiro; Sinclair, Peter J

    2006-08-01

    This study investigated the effect of movement velocity on the relationship between loading intensity and the number of repetitions of bench press. Thirteen healthy men (age = 21.7 +/- 1.0 years; weight = 76.8 +/- 2.5 kg; 1 repetition maximum [1RM] = 99.5 +/- 6.0 kg), who were involved in regular weight training, voluntarily participated in the experiment. Subjects performed bench presses on a Smith machine at 5 different intensities (40-80% 1RM), repeated for 4 velocity conditions (slow: 0.15 +/- 0.03 m.s(-1); medium: 0.32 +/- 0.07 m.s(-1); fast: 0.52 +/- 0.12 m.s(-1); ballistic: maximum velocity), which were randomly assigned over 5 experimental sessions after a 1RM test. Velocity significantly changed the relationship between intensity (%1RM) and the number of reps performed (p velocities producing a higher number of reps. A significant interaction between intensity and velocity meant that velocity had a much greater effect on repetitions at lower intensities. These results suggest that the benefits of using a stretch-shortening cycle during faster movements outweigh the associated disadvantages from the force-velocity relationship. The practical applications of this study are that, when trainees are assigned a resistance training with specific RM values, the lifted intensity (%1RM) or weights will not be consistent unless velocity is controlled during training.

  9. Effects of oncoming target velocities on rapid force production and accuracy of force production intensity and timing.

    Science.gov (United States)

    Ohta, Yoichi

    2017-12-01

    The present study aimed to clarify the effects of oncoming target velocities on the ability of rapid force production and accuracy and variability of simultaneous control of both force production intensity and timing. Twenty male participants (age: 21.0 ± 1.4 years) performed rapid gripping with a handgrip dynamometer to coincide with the arrival of an oncoming target by using a horizontal electronic trackway. The oncoming target velocities were 4, 8, and 12 m · s -1 , which were randomly produced. The grip force required was 30% of the maximal voluntary contraction. Although the peak force (Pf) and rate of force development (RFD) increased with increasing target velocity, the value of the RFD to Pf ratio was constant across the 3 target velocities. The accuracy of both force production intensity and timing decreased at higher target velocities. Moreover, the intrapersonal variability in temporal parameters was lower in the fast target velocity condition, but constant variability in 3 target velocities was observed in force intensity parameters. These results suggest that oncoming target velocity does not intrinsically affect the ability for rapid force production. However, the oncoming target velocity affects accuracy and variability of force production intensity and timing during rapid force production.

  10. Force-Velocity Relationship of Upper Body Muscles: Traditional Versus Ballistic Bench Press.

    Science.gov (United States)

    García-Ramos, Amador; Jaric, Slobodan; Padial, Paulino; Feriche, Belén

    2016-04-01

    This study aimed to (1) evaluate the linearity of the force-velocity relationship, as well as the reliability of maximum force (F0), maximum velocity (V0), slope (a), and maximum power (P0); (2) compare these parameters between the traditional and ballistic bench press (BP); and (3) determine the correlation of F0 with the directly measured BP 1-repetition maximum (1RM). Thirty-two men randomly performed 2 sessions of traditional BP and 2 sessions of ballistic BP during 2 consecutive weeks. Both the maximum and mean values of force and velocity were recorded when loaded by 20-70% of 1RM. All force-velocity relationships were strongly linear (r > .99). While F0 and P0 were highly reliable (ICC: 0.91-0.96, CV: 3.8-5.1%), lower reliability was observed for V0 and a (ICC: 0.49-0.81, CV: 6.6-11.8%). Trivial differences between exercises were found for F0 (ES: velocity relationship is useful to assess the upper body maximal capabilities to generate force, velocity, and power.

  11. Video imaging measurement of interfacial wave velocity in air-water flow through a horizontal elbow

    Science.gov (United States)

    Al-Wazzan, Amir; Than, Cheok F.; Moghavvemi, Mahmoud; Yew, Chia W.

    2001-10-01

    Two-phase flow in pipelines containing elbows represents a common situation in the oil and gas industries. This study deals with the stratified flow regime between the gas and liquid phase through an elbow. It is of interest to study the change in wave characteristics by measuring the wave velocity and wavelength at the inlet and outlet of the elbow. The experiments were performed under concurrent air-water stratified flow in a horizontal transparent polycarbonate pipe of 0.05m diameter and superficial air and water velocities up to 8.97 and 0.0778 m/s respectively. A non-intrusive video imaging technique was applied to capture the waves. For image analysis, a frame by frame direct overlapping method was used to detect for pulsating flow and a pixel shifting method based on the detection of minimum values in the overlap function was used to determine wave velocity and wavelength. Under superficial gas velocity of less than 4.44 m/s, the results suggest a regular pulsating outflow produced by the elbow. At higher gas velocities, more random pulsation was found and the emergence of localized interfacial waves was detected. Wave velocities measured by this technique were found to produce satisfactory agreement with direct measurements.

  12. experimental investigation of sand minimum transport velocity

    African Journals Online (AJOL)

    user

    The production of reservoir fluid through long tiebacks/pipelines has emerged as one of ... transport in multiphase flows, the investigation of the ... Nigerian Journal of Technology ... associated with water-gas-oil-solid flow in pipeline in ... The mixture was well agitated using a .... operational conditions the limit deposit velocity.

  13. How Did Light Acquire a Velocity?

    Science.gov (United States)

    Lauginie, Pierre

    2013-01-01

    We discuss how light acquired a velocity through history, from the ancient Greeks to the early modern era. Combining abstract debates, models of light, practical needs, planned research and chance, this history illustrates several key points that should be brought out in science education.

  14. Ultrasound systems for blood velocity estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1998-01-01

    Medical ultrasound scanners can be used both for displayinggray-scale images of the anatomy and for visualizing theblood flow dynamically in the body.The systems can interrogate the flow at a single position in the bodyand there find the velocity distribution over time. They can also show adynamic...

  15. Wave Velocity Estimation in Heterogeneous Media

    KAUST Repository

    Asiri, Sharefa M.

    2016-03-21

    In this paper, modulating functions-based method is proposed for estimating space-time dependent unknown velocity in the wave equation. The proposed method simplifies the identification problem into a system of linear algebraic equations. Numerical simulations on noise-free and noisy cases are provided in order to show the effectiveness of the proposed method.

  16. CORRELATION BETWEEN UTERINE ARTERY FLOW VELOCITY ...

    African Journals Online (AJOL)

    CORRELATION BETWEEN UTERINE ARTERY FLOW VELOCITY WAVEFORMS AND ENDOMETRIAL HISTOPATHOLOGY IN WOMEN WITH PERIMENOPAUSAL AND POSTMENOPAUSAL BLEEDING. Dr. Ebtesam Saied, Dr. Ismail El Garhy(MD), Dr. Farid I. Hassan(MD), Dr. Adel-Gamil Abd-Allah, Abd El Shafy Ibrahim ...

  17. Velocity Estimation in Medical Ultrasound [Life Sciences

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Villagómez Hoyos, Carlos Armando; Holbek, Simon

    2017-01-01

    This article describes the application of signal processing in medical ultrasound velocity estimation. Special emphasis is on the relation among acquisition methods, signal processing, and estimators employed. The description spans from current clinical systems for one-and two-dimensional (1-D an...

  18. The Microflown, an acoustic particle velocity sensor

    NARCIS (Netherlands)

    de Bree, H.E.

    2003-01-01

    The Microflown is an acoustic sensor directly measuring particle velocity instead of sound pressure, which is usually measured by conventional microphones. Since its invention in 1994 it is mostly used for measurement purposes (broadband1D and 3D-sound intensity measurement and acoustic impedance).

  19. Bubble Swarm Rise Velocity in Fluidized Beds.

    Czech Academy of Sciences Publication Activity Database

    Punčochář, Miroslav; Růžička, Marek; Šimčík, Miroslav

    2016-01-01

    Roč. 152, OCT 2 (2016), s. 84-94 ISSN 0009-2509 R&D Projects: GA ČR(CZ) GA15-05534S Institutional support: RVO:67985858 Keywords : bubbling fluidized bed * gas-solid * bubble swarm velocity Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.895, year: 2016

  20. Velocity distributions in dilute granular systems

    NARCIS (Netherlands)

    van Zon, J.S.; Mac Kintosh, F.C.

    2005-01-01

    We investigate the idea that velocity distributions in granular gases are determined mainly by η, the coefficient of restitution and q, which measures the relative importance of heating (or energy input) to collisions. To this end, we study by numerical simulation the properties of inelastic gases

  1. Electron velocity distributions near collisionless shocks

    International Nuclear Information System (INIS)

    Feldman, W.C.

    1984-01-01

    Recent studies of the amount of electron heating and of the shapes of electron velocity distributions across shocks near the earth are reviewed. It is found that electron heating increases with increasing shock strength but is always less than the ion heating. The scale length of electron heating is also less than that for the ions. Electron velocity distributions show characteristic shapes which depend on the strength of the shocks. At the weaker shocks, electron heating is mostly perpendicular to the ambient magnetic field, bar B, and results in Gaussian-shaped velocity distributions at low-to-moderate energies. At the stronger shocks, parallel heating predominates resulting in flat-topped velocity distributions. A reasonable interpretation of these results indicates that at the weaker shocks electron heating is dominated by a tendency toward conservation of the magnetic moment. At the stronger fast-mode shocks, this heating is thought to be dominated by an acceleration parallel to bar B produced by the macroscopic shock electric field followed by beam driven plasma instabilities. Some contribution to the heating at the stronger shocks from conservation of the magnetic moment and cross-field current-driven instabilities cannot be ruled out. Although the heating at slow-mode shocks is also dominated by instabilities driven by magnetic field-aligned electron beams, their acceleration mechanism is not yet established

  2. Effect of Phase Transformations on Seismic Velocities

    Science.gov (United States)

    Weidner, D. J.; Li, L.; Whitaker, M.; Triplett, R.

    2017-12-01

    The radial velocity structure of the Earth consists of smooth variations of velocities with depth punctuated by abrupt changes of velocity, which are typically due to multivariant phase transformations, where high - low pressure phases can coexist. In this mixed phase region, both the effective shear and bulk moduli will be significantly reduced by the dynamic interaction of the propagating wave and the phase transition if the period of the wave is long enough relative to the kinetic time so that some of the transition can take place. In this presentation, we will give examples from both laboratory studies of phases transitions of Earth minerals and the calculated velocity profile based on our models. We focus on understanding the time limiting factor of the phase transformation in order to extrapolate laboratory results to Earth observations. Both the olivine to ringwoodite transition and KLB-1 partial melting are explored. We find that when the transformation requires diffusion, the kinetics are often slowed down considerably and as a result the diffusivity of atoms become the limiting factor of characteristic time. Specifically Fe-Mg exchange rate in the olivine-ringwoodite phase transition becomes the limiting factor that seismic waves are likely to sample. On the other hand, partial melting is an extremely fast phase transformation at seismic wave periods. We present evidence that ultrasonic waves, with a period of a few tens of nanoseconds, are slowed by the reduction of the effective elastic moduli in this case.

  3. Random tensors

    CERN Document Server

    Gurau, Razvan

    2017-01-01

    Written by the creator of the modern theory of random tensors, this book is the first self-contained introductory text to this rapidly developing theory. Starting from notions familiar to the average researcher or PhD student in mathematical or theoretical physics, the book presents in detail the theory and its applications to physics. The recent detections of the Higgs boson at the LHC and gravitational waves at LIGO mark new milestones in Physics confirming long standing predictions of Quantum Field Theory and General Relativity. These two experimental results only reinforce today the need to find an underlying common framework of the two: the elusive theory of Quantum Gravity. Over the past thirty years, several alternatives have been proposed as theories of Quantum Gravity, chief among them String Theory. While these theories are yet to be tested experimentally, key lessons have already been learned. Whatever the theory of Quantum Gravity may be, it must incorporate random geometry in one form or another....

  4. Frequent Immediate Knowledge of Results Enhances the Increase of Throwing Velocity in Overarm Handball Performance.

    Science.gov (United States)

    Štirn, Igor; Carruthers, Jamie; Šibila, Marko; Pori, Primož

    2017-02-01

    In the present study, the effect of frequent, immediate, augmented feedback on the increase of throwing velocity was investigated. An increase of throwing velocity of a handball set shot when knowledge of results was provided or not provided during training was compared. Fifty female and seventy-three male physical education students were assigned randomly to the experimental or control group. All participants performed two series of ten set shots with maximal effort twice a week for six weeks. The experimental group received information regarding throwing velocity measured by a radar gun immediately after every shot, whereas the control group did not receive any feedback. Measurements of maximal throwing velocity of an ordinary handball and a heavy ball were performed, before and after the training period and compared. Participants who received feedback on results attained almost a four times greater relative increase of the velocity of the normal ball (size 2) as compared to the same intervention when feedback was not provided (8.1 ± 3.6 vs. 2.7 ± 2.9%). The velocity increases were smaller, but still significant between the groups for throws using the heavy ball (5.1 ± 4.2 and 2.5 ± 5.8 for the experimental and control group, respectively). Apart from the experimental group throwing the normal ball, no differences in velocity change for gender were obtained. The results confirmed that training oriented towards an increase in throwing velocity became significantly more effective when frequent knowledge of results was provided.

  5. Prostate specific antigen velocity does not aid prostate cancer detection in men with prior negative biopsy.

    Science.gov (United States)

    Vickers, Andrew J; Wolters, Tineke; Savage, Caroline J; Cronin, Angel M; O'Brien, M Frank; Roobol, Monique J; Aus, Gunnar; Scardino, Peter T; Hugosson, Jonas; Schröder, Fritz H; Lilja, Hans

    2010-09-01

    Prostate specific antigen velocity has been proposed as a marker to aid in prostate cancer detection. We determined whether prostate specific antigen velocity could predict repeat biopsy results in men with persistently increased prostate specific antigen after initial negative biopsy. We identified 1,837 men who participated in the Göteborg or Rotterdam section of the European Randomized Screening study of Prostate Cancer and who underwent 1 or more subsequent prostate biopsies after an initial negative finding. We evaluated whether prostate specific antigen velocity improved predictive accuracy beyond that of prostate specific antigen alone. Of the 2,579 repeat biopsies 363 (14%) were positive for prostate cancer, of which 44 (1.7%) were high grade (Gleason score 7 or greater). Prostate specific antigen velocity was statistically associated with cancer risk but had low predictive accuracy (AUC 0.55, p <0.001). There was some evidence that prostate specific antigen velocity improved AUC compared to prostate specific antigen for high grade cancer. However, the small increase in risk associated with high prostate specific antigen velocity (from 1.7% to 2.8% as velocity increased from 0 to 1 ng/ml per year) had questionable clinical relevance. Men with prior negative biopsy are at lower risk for prostate cancer at subsequent biopsies with high grade disease particularly rare. We found little evidence to support prostate specific antigen velocity to aid in decisions about repeat biopsy for prostate cancer. 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  6. Extreme events as foundation of Levy walks with varying velocity

    International Nuclear Information System (INIS)

    Kutner, Ryszard

    2002-01-01

    In this work we study the role of extreme events [E.W. Montroll, B.J. West, in: J.L. Lebowitz, E.W. Montrell (Eds.), Fluctuation Phenomena, SSM, vol. VII, North-Holland, Amsterdam, 1979, p. 63; J.-P. Bouchaud, M. Potters, Theory of Financial Risks from Statistical Physics to Risk Management, Cambridge University Press, Cambridge, 2001; D. Sornette, Critical Phenomena in Natural Sciences. Chaos, Fractals, Selforganization and Disorder: Concepts and Tools, Springer, Berlin, 2000] in determining the scaling properties of Levy walks with varying velocity. This model is an extension of the well-known Levy walks one [J. Klafter, G. Zumofen, M.F. Shlesinger, in M.F. Shlesinger, G.M. Zaslavsky, U. Frisch (Eds.), Levy Flights and Related Topics ion Physics, Lecture Notes in Physics, vol. 450, Springer, Berlin, 1995, p. 196; G. Zumofen, J. Klafter, M.F. Shlesinger, in: R. Kutner, A. Pekalski, K. Sznajd-Weron (Eds.), Anomalous Diffusion. From Basics to Applications, Lecture Note in Physics, vol. 519, Springer, Berlin, 1999, p. 15] introduced in the context of chaotic dynamics where a fixed value of the walker velocity is assumed for simplicity. Such an extension seems to be necessary when the open and/or complex system is studied. The model of Levy walks with varying velocity is spanned on two coupled velocity-temporal hierarchies: the first one consisting of velocities and the second of corresponding time intervals which the walker spends between the successive turning points. Both these hierarchical structures are characterized by their own self-similar dimensions. The extreme event, which can appear within a given time interval, is defined as a single random step of the walker having largest length. By finding power-laws which describe the time-dependence of this displacement and its statistics we obtained two independent diffusion exponents, which are related to the above-mentioned dimensions and which characterize the extreme event kinetics. In this work we show the

  7. Propagation of the Semidiurnal Internal Tide: Phase Velocity Versus Group Velocity

    Science.gov (United States)

    Zhao, Zhongxiang

    2017-12-01

    The superposition of two waves of slightly different wavelengths has long been used to illustrate the distinction between phase velocity and group velocity. The first-mode M2 and S2 internal tides exemplify such a two-wave model in the natural ocean. The M2 and S2 tidal frequencies are 1.932 and 2 cycles per day, respectively, and their superposition forms a spring-neap cycle in the semidiurnal band. The spring-neap cycle acts like a wave, with its frequency, wave number, and phase being the differences of the M2 and S2 internal tides. The spring-neap cycle and energy of the semidiurnal internal tide propagate at the group velocity. Long-range propagation of M2 and S2 internal tides in the North Pacific is observed by satellite altimetry. Along a 3,400 km beam spanning 24°-54°N, the M2 and S2 travel times are 10.9 and 11.2 days, respectively. For comparison, it takes the spring-neap cycle 21.1 days to travel over this distance. Spatial maps of the M2 phase velocity, the S2 phase velocity, and the group velocity are determined from phase gradients of the corresponding satellite observed internal tide fields. The observed phase and group velocities agree with theoretical values estimated using the World Ocean Atlas 2013 annual-mean ocean stratification.

  8. An improved estimation and focusing scheme for vector velocity estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Munk, Peter

    1999-01-01

    to reduce spatial velocity dispersion. Examples of different velocity vector conditions are shown using the Field II simulation program. A relative accuracy of 10.1 % is obtained for the lateral velocity estimates for a parabolic velocity profile for a flow perpendicular to the ultrasound beam and a signal...

  9. Consideration of wear rates at high velocity

    Science.gov (United States)

    Hale, Chad S.

    The development of the research presented here is one in which high velocity relative sliding motion between two bodies in contact has been considered. Overall, the wear environment is truly three-dimensional. The attempt to characterize three-dimensional wear was not economically feasible because it must be analyzed at the micro-mechanical level to get results. Thus, an engineering approximation was carried out. This approximation was based on a metallographic study identifying the need to include viscoplasticity constitutive material models, coefficient of friction, relationships between the normal load and velocity, and the need to understand wave propagation. A sled test run at the Holloman High Speed Test Track (HHSTT) was considered for the determination of high velocity wear rates. In order to adequately characterize high velocity wear, it was necessary to formulate a numerical model that contained all of the physical events present. The experimental results of a VascoMax 300 maraging steel slipper sliding on an AISI 1080 steel rail during a January 2008 sled test mission were analyzed. During this rocket sled test, the slipper traveled 5,816 meters in 8.14 seconds and reached a maximum velocity of 1,530 m/s. This type of environment was never considered previously in terms of wear evaluation. Each of the features of the metallography were obtained through micro-mechanical experimental techniques. The byproduct of this analysis is that it is now possible to formulate a model that contains viscoplasticity, asperity collisions, temperature and frictional features. Based on the observations of the metallographic analysis, these necessary features have been included in the numerical model, which makes use of a time-dynamic program which follows the movement of a slipper during its experimental test run. The resulting velocity and pressure functions of time have been implemented in the explicit finite element code, ABAQUS. Two-dimensional, plane strain models

  10. The radial velocity, velocity dispersion, and mass-to-light ratio of the Sculptor dwarf galaxy

    Science.gov (United States)

    Armandroff, T. E.; Da Costa, G. S.

    1986-01-01

    The radial velocity, velocity dispersion, and mass-to-light ratio for 16 K giants in the Sculptor dwarf galaxy are calculated. Spectra at the Ca II triplet are analyzed using cross-correlation techniques in order to obtain the mean velocity of + 107.4 + or - 2.0 km/s. The dimensional velocity dispersion estimated as 6.3 (+1.1, -1.3) km/s is combined with the calculated core radius and observed central surface brightness to produce a mass-to-light ratio of 6.0 in solar units. It is noted that the data indicate that the Sculptor contains a large amount of mass not found in globular clusters, and the mass is either in the form of remnant stars or low-mass dwarfs.

  11. Thought experiments at superluminal relative velocities

    International Nuclear Information System (INIS)

    Corben, H.C.

    1976-01-01

    It is imagined that our World is being examined from a similar world which is moving relative to us with a velocity greater than that of light. The two worlds are supposed to be similar in that the particles in each appear to any observer in that world to have real measurable properties. However, the enormous relative velocity so distorts the observations that each world makes on the other that the squares of certain real quantities appear to the other observer to be negative. Neglect of this fact has led to the erroneous belief that a free charged tachyon would emit Cherenkov radiation and that the existence of tachyons would lead to logical paradoxes. (author)

  12. Measuring probe for measurement of local velocities

    International Nuclear Information System (INIS)

    Casal, V.; Arnold, G.; Kirchner, R.; Kussmaul, H.; Miller, H.

    1988-03-01

    The report describes a method for measurement of local velocities. It bases on the detection of the propagation of a temperature pulse induced into the fluid. The method can also be applied in flowing liquid metals with superimposed magnetic field; in this case common measuring principles fail application. The measuring system discussed consists of, a measuring head, a heating system, amplifiers and a PC. The latter performs process operation, data sampling, and evaluation of velocity. The measuring head itself includes a miniaturized heater (as a pulse marker) heated by the heating system in a short pulse, and a number of thermocouples (sensors) for detection of signals. The design, construction, and examination of a developed measuring device is described. (orig.) [de

  13. Self-consistent velocity dependent effective interactions

    International Nuclear Information System (INIS)

    Kubo, Takayuki; Sakamoto, Hideo; Kammuri, Tetsuo; Kishimoto, Teruo.

    1993-09-01

    The field coupling method is extended to a system with a velocity dependent mean potential. By means of this method, we can derive the effective interactions which are consistent with the mean potential. The self-consistent velocity dependent effective interactions are applied to the microscopic analysis of the structures of giant dipole resonances (GDR) of 148,154 Sm, of the first excited 2 + states of Sn isotopes and of the first excited 3 - states of Mo isotopes. It is clarified that the interactions play crucial roles in describing the splitting of the resonant structure of GDR peaks, in restoring the energy weighted sum rule values, and in reducing B (Eλ) values. (author)

  14. Solar wind velocity and geomagnetic moment variations

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Rozanova, T.S.

    1982-01-01

    The mean year values of the solar wind velocity have been calculated from the mean-year values of a geomagnetic activity index am according to the Svalgard equation of regression for the pe-- riod from 1930 to 1960. For the same years the values of the geomagnetic moment M and separately of its ''inner'' (causes of which'' are inside the Earth) and ''external'' (causes of which are outside the Earth) parts have been calculated from the mean year data of 12 magnetic observatories. The proof of the presence of the 11-year variation in the moment M has been obtained. It is concluded that the 11-year variations in M result from the variations of the solar wind velocity

  15. On the theory of turbulent flame velocity

    OpenAIRE

    Bychkov, Vitaly; Akkerman, Vyacheslav; Petchenko, Arkady

    2012-01-01

    The renormalization ideas of self-similar dynamics of a strongly turbulent flame front are applied to the case of a flame with realistically large thermal expansion of the burning matter. In that case a flame front is corrugated both by external turbulence and the intrinsic flame instability. The analytical formulas for the velocity of flame propagation are obtained. It is demonstrated that the flame instability is of principal importance when the integral turbulent length scale is much large...

  16. Temporal Changes of the Photospheric Velocity Fields

    Czech Academy of Sciences Publication Activity Database

    Klvaňa, Miroslav; Švanda, Michal; Bumba, Václav

    2005-01-01

    Roč. 29, č. 1 (2005), s. 89-98 ISSN 0351-2657. [Hvar astrophysical colloquium /7./: Solar activity cycle and global phenomena. Hvar, 20.09.2004-24.09.2004] R&D Projects: GA ČR GA205/04/2129 Institutional research plan: CEZ:AV0Z10030501 Keywords : Solar photosphere * velocity fields * tidal waves Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  17. Handwriting Velocity Modeling by Artificial Neural Networks

    OpenAIRE

    Mohamed Aymen Slim; Afef Abdelkrim; Mohamed Benrejeb

    2014-01-01

    The handwriting is a physical demonstration of a complex cognitive process learnt by man since his childhood. People with disabilities or suffering from various neurological diseases are facing so many difficulties resulting from problems located at the muscle stimuli (EMG) or signals from the brain (EEG) and which arise at the stage of writing. The handwriting velocity of the same writer or different writers varies according to different criteria: age, attitude, mood, wr...

  18. Anisotropy of dark matter velocity distribution

    OpenAIRE

    Nagao, Keiko I.

    2018-01-01

    Direct detection of dark matter with directional sensitivity has the potential to discriminate the dark matter velocity distribution. Especially, it will be suitable to discriminate isotropic distribution from anisotropic one. Analyzing data produced with Monte-Carlo simulation, required conditions for the discrimination is estimated. If energy threshold of detector is optimized, $O(10^3-10^4)$ event number is required to discriminate the anisotropy.

  19. Advances in constant-velocity Moessbauer instrumentation

    International Nuclear Information System (INIS)

    Veiga, A.; Martinez, N.; Zelis, P. Mendoza; Pasquevich, G. A.; Sanchez, F. H.

    2006-01-01

    A prototype of a programmable constant-velocity scaler is presented. This instrument allows the acquisition of partial Moessbauer spectra in selected energy regions using standard drivers and transducers. It can be fully operated by a remote application, thus data acquisition can be automated. The instrument consists of a programmable counter and a constant-velocity reference. The reference waveform generator is amplitude modulated with 13-bit resolution, and is programmable in a wide range of frequencies and waveforms in order to optimize the performance of the transducer. The counter is compatible with most standard SCA, and is configured as a rate-meter that provides counts per selectable time slice at the programmed velocity. As a demonstration of the instrument applications, a partial Moessbauer spectrum of a natural iron foil was taken. Only positive energies were studied in 512 channels, accumulating 20 s per channel. A line width of 0.20 mm/s was achieved, performing with an efficiency of 80%.

  20. Climatology of tropospheric vertical velocity spectra

    Science.gov (United States)

    Ecklund, W. L.; Gage, K. S.; Balsley, B. B.; Carter, D. A.

    1986-01-01

    Vertical velocity power spectra obtained from Poker Flat, Alaska; Platteville, Colorado; Rhone Delta, France; and Ponape, East Caroline Islands using 50-MHz clear-air radars with vertical beams are given. The spectra were obtained by analyzing the quietest periods from the one-minute-resolution time series for each site. The lengths of available vertical records ranged from as long as 6 months at Poker Flat to about 1 month at Platteville. The quiet-time vertical velocity spectra are shown. Spectral period ranging from 2 minutes to 4 hours is shown on the abscissa and power spectral density is given on the ordinate. The Brunt-Vaisala (B-V) periods (determined from nearby sounding balloons) are indicated. All spectra (except the one from Platteville) exhibit a peak at periods slightly longer than the B-V period, are flat at longer periods, and fall rapidly at periods less than the B-V period. This behavior is expected for a spectrum of internal waves and is very similar to what is observed in the ocean (Eriksen, 1978). The spectral amplitudes vary by only a factor of 2 or 3 about the mean, and show that under quiet conditions vertical velocity spectra from the troposphere are very similar at widely different locations.

  1. A neural circuit for angular velocity computation

    Directory of Open Access Journals (Sweden)

    Samuel B Snider

    2010-12-01

    Full Text Available In one of the most remarkable feats of motor control in the animal world, some Diptera, such as the housefly, can accurately execute corrective flight maneuvers in tens of milliseconds. These reflexive movements are achieved by the halteres, gyroscopic force sensors, in conjunction with rapidly-tunable wing-steering muscles. Specifically, the mechanosensory campaniform sensilla located at the base of the halteres transduce and transform rotation-induced gyroscopic forces into information about the angular velocity of the fly's body. But how exactly does the fly's neural architecture generate the angular velocity from the lateral strain forces on the left and right halteres? To explore potential algorithms, we built a neuro-mechanical model of the rotation detection circuit. We propose a neurobiologically plausible method by which the fly could accurately separate and measure the three-dimensional components of an imposed angular velocity. Our model assumes a single sign-inverting synapse and formally resembles some models of directional selectivity by the retina. Using multidimensional error analysis, we demonstrate the robustness of our model under a variety of input conditions. Our analysis reveals the maximum information available to the fly given its physical architecture and the mathematics governing the rotation-induced forces at the haltere's end knob.

  2. Seismic Wave Velocity in Earth's Shallow Core

    Science.gov (United States)

    Alexandrakis, C.; Eaton, D. W.

    2008-12-01

    Studies of the outer core indicate that it is composed of liquid Fe and Ni alloyed with a ~10% fraction of light elements such as O, S or Si. Recently, unusual features, such as sediment accumulation, immiscible fluid layers or stagnant convection, have been predicted in the shallow core region. Secular cooling and compositional buoyancy drive vigorous convection that sustains the geodynamo, although critical details of light-element composition and thermal regime remain uncertain. Seismic velocity models can provide important constraints on the light element composition, however global reference models, such as Preliminary Reference Earth Model (PREM), IASP91 and AK135 vary significantly in the 200 km below the core-mantle boundary. Past studies of the outermost core velocity structure have been hampered by traveltime uncertainties due to lowermost mantle heterogeneities. The recently published Empirical Transfer Function (ETF) method has been shown to reduce the uncertainty using a waveform stacking approach to improve global observations of SmKS teleseismic waves. Here, we apply the ETF method to achieve a precise top-of-core velocity measurement of 8.05 ± 0.03 km/s. This new model accords well with PREM. Since PREM is based on the adiabatic form of the Adams-Williamson equation, it assumes a well mixed (i.e. homogeneous) composition. This result suggests a lack of heterogeneity in the outermost core due to layering or stagnant convection.

  3. Lagrangian velocity correlations in homogeneous isotropic turbulence

    International Nuclear Information System (INIS)

    Gotoh, T.; Rogallo, R.S.; Herring, J.R.; Kraichnan, R.H.

    1993-01-01

    The Lagrangian velocity autocorrelation and the time correlations for individual wave-number bands are computed by direct numerical simulation (DNS) using the passive vector method (PVM), and the accuracy of the method is studied. It is found that the PVM is accurate when K max /k d ≥2 where K max is the maximum wave number carried in the simulation and k d is the Kolmogorov wave number. The Eulerian and Lagrangian time correlations for various wave-number bands are compared. At moderate to high wave number the Eulerian time correlation decays faster than the Lagrangian, and the effect of sweep on the former is observed. The time scale of the Eulerian correlation is found to be (kU 0 ) -1 while that of the Lagrangian is [∫ 0 k p 2 E(p)dp] -1/2 . The Lagrangian velocity autocorrelation in a frozen turbulent field is computed using the DIA, ALHDIA, and LRA theories and is compared with DNS measurements. The Markovianized Lagrangian renormalized approximation (MLRA) is compared with the DNS, and good agreement is found for one-time quantities in decaying turbulence at low Reynolds numbers and for the Lagrangian velocity autocorrelation in stationary turbulence at moderate Reynolds number. The effect of non-Gaussianity on the Lagrangian correlation predicted by the theories is also discussed

  4. Fatigue influences lower extremity angular velocities during a single-leg drop vertical jump

    OpenAIRE

    Tamura, Akihiro; Akasaka, Kiyokazu; Otsudo, Takahiro; Shiozawa, Junya; Toda, Yuka; Yamada, Kaori

    2017-01-01

    [Purpose] Fatigue alters lower extremity landing strategies and decreases the ability to attenuate impact during landing. The purpose of this study was to reveal the influence of fatigue on dynamic alignment and joint angular velocities in the lower extremities during a single leg landing. [Subjects and Methods] The 34 female college students were randomly assigned to either the fatigue or control group. The fatigue group performed single-leg drop vertical jumps before, and after, the fatigue...

  5. Effects of A 6-Week Junior Tennis Conditioning Program on Service Velocity

    OpenAIRE

    Fernandez-Fernandez, Jaime; Ellenbecker, Todd; Sanz-Rivas, david; Ulbricht, Alexander; Ferrautia, lexander

    2013-01-01

    This study examined the effects of a 6-week strength-training program on serve velocity in youth tennis players. Thirty competitive healthy and nationally ranked male junior tennis players (13 years of age) were randomly and equally divided into control and training groups. The training group performed 3 sessions (60-70 min) weekly for 6 weeks, comprising core strength, elastic resistance and medicine ball exercises. Both groups (control and training) also performed a supervised stretching ro...

  6. Collective cell migration without proliferation: density determines cell velocity and wave velocity

    Science.gov (United States)

    Tlili, Sham; Gauquelin, Estelle; Li, Brigitte; Cardoso, Olivier; Ladoux, Benoît; Delanoë-Ayari, Hélène; Graner, François

    2018-05-01

    Collective cell migration contributes to embryogenesis, wound healing and tumour metastasis. Cell monolayer migration experiments help in understanding what determines the movement of cells far from the leading edge. Inhibiting cell proliferation limits cell density increase and prevents jamming; we observe long-duration migration and quantify space-time characteristics of the velocity profile over large length scales and time scales. Velocity waves propagate backwards and their frequency depends only on cell density at the moving front. Both cell average velocity and wave velocity increase linearly with the cell effective radius regardless of the distance to the front. Inhibiting lamellipodia decreases cell velocity while waves either disappear or have a lower frequency. Our model combines conservation laws, monolayer mechanical properties and a phenomenological coupling between strain and polarity: advancing cells pull on their followers, which then become polarized. With reasonable values of parameters, this model agrees with several of our experimental observations. Together, our experiments and model disantangle the respective contributions of active velocity and of proliferation in monolayer migration, explain how cells maintain their polarity far from the moving front, and highlight the importance of strain-polarity coupling and density in long-range information propagation.

  7. Correlation of right atrial appendage velocity with left atrial appendage velocity and brain natriuretic Peptide.

    Science.gov (United States)

    Kim, Bu-Kyung; Heo, Jung-Ho; Lee, Jae-Woo; Kim, Hyun-Soo; Choi, Byung-Joo; Cha, Tae-Joon

    2012-03-01

    Left atrial appendage (LAA) anatomy and function have been well characterized both in healthy and diseased people, whereas relatively little attention has been focused on the right atrial appendage (RAA). We sought to evaluate RAA flow velocity and to compare these parameters with LAA indices and with a study of biomarkers, such as brain natriuretic peptide, among patients with sinus rhythm (SR) and atrial fibrillation (AF). In a series of 79 consecutive patients referred for transesophageal echocardiography, 43 patients (23 with AF and 20 controls) were evaluated. AF was associated with a decrease in flow velocity for both LAA and RAA [LAA velocity-SR vs. AF: 61 ± 22 vs. 29 ± 18 m/sec (p vs. AF: 46 ± 20 vs. 19 ± 8 m/sec (p brain natriuretic peptide (BNP). AF was associated with decreased RAA and LAA flow velocities. RAA velocity was found to be positively correlated with LAA velocity and negatively correlated with BNP. The plasma BNP concentration may serve as a determinant of LAA and RAA functions.

  8. Random pulse generator

    International Nuclear Information System (INIS)

    Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

    2007-01-01

    Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

  9. Random matrices and random difference equations

    International Nuclear Information System (INIS)

    Uppuluri, V.R.R.

    1975-01-01

    Mathematical models leading to products of random matrices and random difference equations are discussed. A one-compartment model with random behavior is introduced, and it is shown how the average concentration in the discrete time model converges to the exponential function. This is of relevance to understanding how radioactivity gets trapped in bone structure in blood--bone systems. The ideas are then generalized to two-compartment models and mammillary systems, where products of random matrices appear in a natural way. The appearance of products of random matrices in applications in demography and control theory is considered. Then random sequences motivated from the following problems are studied: constant pulsing and random decay models, random pulsing and constant decay models, and random pulsing and random decay models

  10. Velocities of Subducted Sediments and Continents

    Science.gov (United States)

    Hacker, B. R.; van Keken, P. E.; Abers, G. A.; Seward, G.

    2009-12-01

    The growing capability to measure seismic velocities in subduction zones has led to unusual observations. For example, although most minerals have VP/ VS ratios around 1.77, ratios 1.8 have been observed. Here we explore the velocities of subducted sediments and continental crust from trench to sub-arc depths using two methods. (1) Mineralogy was calculated as a function of P & T for a range of subducted sediment compositions using Perple_X, and rock velocities were calculated using the methodology of Hacker & Abers [2004]. Calculated slab-top temperatures have 3 distinct depth intervals with different dP/dT gradients that are determined by how coupling between the slab and mantle wedge is modeled. These three depth intervals show concomitant changes in VP and VS: velocities initially increase with depth, then decrease beyond the modeled decoupling depth where induced flow in the wedge causes rapid heating, and increase again at depth. Subducted limestones, composed chiefly of aragonite, show monotonic increases in VP/ VS from 1.63 to 1.72. Cherts show large jumps in VP/ VS from 1.55-1.65 to 1.75 associated with the quartz-coesite transition. Terrigenous sediments dominated by quartz and mica show similar, but more-subdued, transitions from ~1.67 to 1.78. Pelagic sediments dominated by mica and clinopyroxene show near-monotonic increases in VP/ VS from 1.74 to 1.80. Subducted continental crust that is too dry to transform to high-pressure minerals has a VP/ VS ratio of 1.68-1.70. (2) Velocity anisotropy calculations were made for the same P-T dependent mineralogies using the Christoffel equation and crystal preferred orientations measured via electron-backscatter diffraction for typical constituent phases. The calculated velocity anisotropies range from 5-30%. For quartz-rich rocks, the calculated velocities show a distinct depth dependence because crystal slip systems and CPOs change with temperature. In such rocks, the fast VP direction varies from slab-normal at

  11. CONSTRAINING THE NFW POTENTIAL WITH OBSERVATIONS AND MODELING OF LOW SURFACE BRIGHTNESS GALAXY VELOCITY FIELDS

    International Nuclear Information System (INIS)

    Kuzio de Naray, Rachel; McGaugh, Stacy S.; Mihos, J. Christopher

    2009-01-01

    We model the Navarro-Frenk-White (NFW) potential to determine if, and under what conditions, the NFW halo appears consistent with the observed velocity fields of low surface brightness (LSB) galaxies. We present mock DensePak Integral Field Unit (IFU) velocity fields and rotation curves of axisymmetric and nonaxisymmetric potentials that are well matched to the spatial resolution and velocity range of our sample galaxies. We find that the DensePak IFU can accurately reconstruct the velocity field produced by an axisymmetric NFW potential and that a tilted-ring fitting program can successfully recover the corresponding NFW rotation curve. We also find that nonaxisymmetric potentials with fixed axis ratios change only the normalization of the mock velocity fields and rotation curves and not their shape. The shape of the modeled NFW rotation curves does not reproduce the data: these potentials are unable to simultaneously bring the mock data at both small and large radii into agreement with observations. Indeed, to match the slow rise of LSB galaxy rotation curves, a specific viewing angle of the nonaxisymmetric potential is required. For each of the simulated LSB galaxies, the observer's line of sight must be along the minor axis of the potential, an arrangement that is inconsistent with a random distribution of halo orientations on the sky.

  12. Shape plasticity in response to water velocity in the freshwater blenny Salaria fluviatilis.

    Science.gov (United States)

    Laporte, M; Claude, J; Berrebi, P; Perret, P; Magnan, P

    2016-03-01

    A non-random association between an environmental factor and a given trait could be explained by directional selection (genetic determinism) and by phenotypic plasticity (environmental determinism). A previous study showed a significant relationship between morphology and water velocity in Salaria fluviatilis that conformed to functional expectations. The objective of this study was to test whether this relationship could be explained by phenotypic plasticity. Salaria fluviatilis from a Corsican stream were placed in four experimental channels with different water velocities (0, 10, 20 and 30 cm s(-1)) to test whether there was a morphological response associated with this environmental factor. After 28 days, fish shape changed in response to water velocity without any significant growth. Fish in higher water velocities exhibited a more slender body shape and longer anal and caudal fins. These results indicate a high degree of morphological plasticity in riverine populations of S. fluviatilis and suggest that the previous relationship between morphology and water velocity observed in the field may largely be due to an environmental determinism. © 2016 The Fisheries Society of the British Isles.

  13. Development and Validity of a Scale of Perception of Velocity in Resistance Exercise

    Directory of Open Access Journals (Sweden)

    Iker J. Bautista

    2014-09-01

    Full Text Available This aims of this study were twofold; 1 to development a new scale of perceived velocity in the bench press exercise and 2 to examine the scales concurrent validity. Twenty one physically active males with mean ±SD age, height and weights of: 27.5 ± 4.7 years, 1.77 ± 0.07 m, and 79.8 ± 10.3 kg respectively, took part in the study. The criterion variable used to test the validity of the new scale was the mean execution velocity (Velreal of the bench press exercise. Three intensities (light loads [ 70% 1RM] were measured randomly during 5 days of testing. Perceived velocity (Velscale was measured immediately after each exercise set using the new scale. A positive linear correlation (r range = 0.69 to 0.81 was found in all three intensities, analyzed individually, between the Velreal and Velscale. Pearson correlations showed a greater frequency of scale use resulted higher correlation values (range r = 0.88 to 0.96. This study provides evidence of the concurrent validity of a new scale of perceived velocity in the bench press exercise in trained adult males. These results suggest the exercise intensity of the bench press can be quantified quickly and effective using this new scale of perceived velocity, particularly when training for maximum power.

  14. Velocity- and power-load relationships of the bench pull vs. bench press exercises.

    Science.gov (United States)

    Sánchez-Medina, L; González-Badillo, J J; Pérez, C E; Pallarés, J G

    2014-03-01

    This study compared the velocity- and power-load relationships of the antagonistic upper-body exercises of prone bench pull (PBP) and bench press (BP). 75 resistance-trained athletes performed a progressive loading test in each exercise up to the one-repetition maximum (1RM) in random order. Velocity and power output across the 30-100% 1RM were significantly higher for PBP, whereas 1RM strength was greater for BP. A very close relationship was observed between relative load and mean propulsive velocity for both BP (R2=0.97) and PBP (R2=0.94) which enables us to estimate %1RM from velocity using the obtained prediction equations. Important differences in the load that maximizes power output (Pmax) and the power profiles of both exercises were found according to the outcome variable used: mean (MP), peak (PP) or mean propulsive power (MPP). When MP was considered, the Pmax load was higher (56% BP, 70% PBP) than when PP (37% BP, 41% PBP) or MPP (37% BP, 46% PBP) were used. For each variable there was a broad range of loads at which power output was not significantly different. The differing velocity- and power-load relationships between PBP and BP seem attributable to the distinct muscle architecture and moment arm levers involved in these exercises. © Georg Thieme Verlag KG Stuttgart · New York.

  15. Optimal velocity difference model for a car-following theory

    International Nuclear Information System (INIS)

    Peng, G.H.; Cai, X.H.; Liu, C.Q.; Cao, B.F.; Tuo, M.X.

    2011-01-01

    In this Letter, we present a new optimal velocity difference model for a car-following theory based on the full velocity difference model. The linear stability condition of the new model is obtained by using the linear stability theory. The unrealistically high deceleration does not appear in OVDM. Numerical simulation of traffic dynamics shows that the new model can avoid the disadvantage of negative velocity occurred at small sensitivity coefficient λ in full velocity difference model by adjusting the coefficient of the optimal velocity difference, which shows that collision can disappear in the improved model. -- Highlights: → A new optimal velocity difference car-following model is proposed. → The effects of the optimal velocity difference on the stability of traffic flow have been explored. → The starting and braking process were carried out through simulation. → The effects of the optimal velocity difference can avoid the disadvantage of negative velocity.

  16. Distinguishing zero-group-velocity modes in photonic crystals

    International Nuclear Information System (INIS)

    Ghebrebrhan, M.; Ibanescu, M.; Johnson, Steven G.; Soljacic, M.; Joannopoulos, J. D.

    2007-01-01

    We examine differences between various zero-group-velocity modes in photonic crystals, including those that arise from Bragg diffraction, anticrossings, and band repulsion. Zero-group velocity occurs at points where the group velocity changes sign, and therefore is conceptually related to 'left-handed' media, in which the group velocity is opposite to the phase velocity. We consider this relationship more quantitatively in terms of the Fourier decomposition of the modes, by defining a measure of how much the ''average'' phase velocity is parallel to the group velocity--an anomalous region is one in which they are mostly antiparallel. We find that this quantity can be used to qualitatively distinguish different zero-group-velocity points. In one dimension, such anomalous regions are found never to occur. In higher dimensions, they are exhibited around certain zero-group-velocity points, and lead to unusual enhanced confinement behavior in microcavities

  17. Influence of perturbation velocity on balance control in Parkinson's disease.

    Directory of Open Access Journals (Sweden)

    Lars B Oude Nijhuis

    Full Text Available Underlying somatosensory processing deficits of joint rotation velocities may cause patients with Parkinson's disease (PD to be more unstable for fast rather than slow balance perturbations. Such deficits could lead to reduced proprioceptive amplitude feedback triggered by perturbations, and thereby to smaller or delayed stabilizing postural responses. For this reason, we investigated whether support surface perturbation velocity affects balance reactions in PD patients. We examined postural responses of seven PD patients (OFF medication and eight age-matched controls following backward rotations of a support-surface platform. Rotations occurred at three different speeds: fast (60 deg/s, medium (30 deg/s or slow (3.8 deg/s, presented in random order. Each subject completed the protocol under eyes open and closed conditions. Full body kinematics, ankle torques and the number of near-falls were recorded. Patients were significantly more unstable than controls following fast perturbations (26% larger displacements of the body's centre of mass; P<0.01, but not following slow perturbations. Also, more near-falls occurred in patients for fast rotations. Balance correcting ankle torques were weaker for patients than controls on the most affected side, but were stronger than controls for the least affected side. These differences were present both with eyes open and eyes closed (P<0.01. Fast support surface rotations caused greater instability and discriminated Parkinson patients better from controls than slow rotations. Although ankle torques on the most affected side were weaker, patients partially compensated for this by generating larger than normal stabilizing torques about the ankle joint on the least affected side. Without this compensation, instability may have been greater.

  18. Influence of Velocity on Variability in Gait Kinematics

    DEFF Research Database (Denmark)

    Yang, Sylvia X M; Larsen, Peter K; Alkjær, Tine

    2014-01-01

    the concurrence of joint angles throughout a gait cycle at three different velocities (3.0, 4.5, 6.0 km/h). Six datasets at each velocity were collected from 16 men. A variability range VR throughout the gait cycle at each velocity for each joint angle for each person was calculated. The joint angles at each...... velocity were compared pairwise, and whenever this showed values within the VR of this velocity, the case was positive. By adding the positives throughout the gait cycle, phases with high and low concurrences were located; peak concurrence was observed at mid-stance phase. Striving for the same velocity...

  19. Uncertainty assessment of 3D instantaneous velocity model from stack velocities

    Science.gov (United States)

    Emanuele Maesano, Francesco; D'Ambrogi, Chiara

    2015-04-01

    3D modelling is a powerful tool that is experiencing increasing applications in data analysis and dissemination. At the same time the need of quantitative uncertainty evaluation is strongly requested in many aspects of the geological sciences and by the stakeholders. In many cases the starting point for 3D model building is the interpretation of seismic profiles that provide indirect information about the geology of the subsurface in the domain of time. The most problematic step in the 3D modelling construction is the conversion of the horizons and faults interpreted in time domain to the depth domain. In this step the dominant variable that could lead to significantly different results is the velocity. The knowledge of the subsurface velocities is related mainly to punctual data (sonic logs) that are often sparsely distributed in the areas covered by the seismic interpretation. The extrapolation of velocity information to wide extended horizons is thus a critical step to obtain a 3D model in depth that can be used for predictive purpose. In the EU-funded GeoMol Project, the availability of a dense network of seismic lines (confidentially provided by ENI S.p.A.) in the Central Po Plain, is paired with the presence of 136 well logs, but few of them have sonic logs and in some portion of the area the wells are very widely spaced. The depth conversion of the 3D model in time domain has been performed testing different strategies for the use and the interpolation of velocity data. The final model has been obtained using a 4 layer cake 3D instantaneous velocity model that considers both the initial velocity (v0) in every reference horizon and the gradient of velocity variation with depth (k). Using this method it is possible to consider the geological constraint given by the geometries of the horizons and the geo-statistical approach to the interpolation of velocities and gradient. Here we present an experiment based on the use of set of pseudo-wells obtained from the

  20. Quantifying seasonal velocity at Khumbu Glacier, Nepal

    Science.gov (United States)

    Miles, E.; Quincey, D. J.; Miles, K.; Hubbard, B. P.; Rowan, A. V.

    2017-12-01

    While the low-gradient debris-covered tongues of many Himalayan glaciers exhibit low surface velocities, quantifying ice flow and its variation through time remains a key challenge for studies aimed at determining the long-term evolution of these glaciers. Recent work has suggested that glaciers in the Everest region of Nepal may show seasonal variability in surface velocity, with ice flow peaking during the summer as monsoon precipitation provides hydrological inputs and thus drives changes in subglacial drainage efficiency. However, satellite and aerial observations of glacier velocity during the monsoon are greatly limited due to cloud cover. Those that do exist do not span the period over which the most dynamic changes occur, and consequently short-term (i.e. daily) changes in flow, as well as the evolution of ice dynamics through the monsoon period, remain poorly understood. In this study, we combine field and remote (satellite image) observations to create a multi-temporal, 3D synthesis of ice deformation rates at Khumbu Glacier, Nepal, focused on the 2017 monsoon period. We first determine net annual and seasonal surface displacements for the whole glacier based on Landsat-8 (OLI) panchromatic data (15m) processed with ImGRAFT. We integrate inclinometer observations from three boreholes drilled by the EverDrill project to determine cumulative deformation at depth, providing a 3D perspective and enabling us to assess the role of basal sliding at each site. We additionally analyze high-frequency on-glacier L1 GNSS data from three sites to characterize variability within surface deformation at sub-seasonal timescales. Finally, each dataset is validated against repeat-dGPS observations at gridded points in the vicinity of the boreholes and GNSS dataloggers. These datasets complement one another to infer thermal regime across the debris-covered ablation area of the glacier, and emphasize the seasonal and spatial variability of ice deformation for glaciers in High

  1. H0, q0 and the local velocity field. [Hubble and deceleration constants in Big Bang expansion

    Science.gov (United States)

    Sandage, A.; Tammann, G. A.

    1982-01-01

    An attempt is made to find a systematic deviation from linearity for distances that are under the control of the Virgo cluster, and to determine the value of the mean random motion about the systematic flow, in order to improve the measurement of the Hubble and the deceleration constants. The velocity-distance relation for large and intermediate distances is studied, and type I supernovae are calibrated relatively as distance indicators and absolutely to obtain a new value for the Hubble constant. Methods of determining the deceleration constant are assessed, including determination from direct measurement, mean luminosity density, virgocentric motion, and the time scale test. The very local velocity field is investigated, and a solution is preferred with a random peculiar radial velocity of very nearby field galaxies of 90-100 km/s, and a Virgocentric motion of the local group of 220 km/s, leading to an underlying expansion rate of 55, in satisfactory agreement with the global value.

  2. Superconducting RF for Low-Velocity and Intermediate-Velocity Beams

    CERN Document Server

    Grimm, Terry L

    2005-01-01

    Existing superconducting radio frequency (SRF) linacs are used to accelerate ions (protons through uranium) with velocities less than about 15% the speed of light, or electrons with velocities approximately equal to the speed of light. In the last ten years, prototype SRF cavities have completely covered the remaining range of velocities. They have demonstrated that SRF linacs will be capable of accelerating electrons from rest up to the speed of light, and ions from less than 1% up to the speed of light. When the Spallation Neutron Source is operational, SRF ion linacs will have covered the full range of velocities except for v/c ~ 0.15 to v/c ~ 0.5. A number of proposed projects (RIA, EURISOL) would span the latter range of velocities. Future SRF developments will have to address the trade-offs associated with a number of issues, including high gradient operation, longitudinal and transverse acceptance, microphonics, Lorentz detuning, operating temperature, cryogenic load, number of gaps or cells per cavity...

  3. Free-surface velocity measurements using an optically recording velocity interferometer

    International Nuclear Information System (INIS)

    Lu Jianxin; Wang Zhao; Liang Jing; Shan Yusheng; Zhou Chuangzhi; Xiang Yihuai; Lu Ze; Tang Xiuzhang

    2006-01-01

    An optically recording velocity interferometer system (ORVIS) was developed for the free-surface velocity measurements in the equation of state experiments. The time history of free-surface velocity could be recorded by the electronic streak camera. In the experiments, ORVIS got a 179 ps time resolution, and a higher time resolution could be got by minimizing the delay time. The equation of state experiments were carried out on the high power excimer laser system called 'Heaven I' with laser wavelength of 248.4 nm, pulse duration of 25 ns and maximum energy 158 J. Free-surface velocity of 20 μm thick iron got 3.86 km/s with laser intensity of 6.24 x 10 11 W·cm -2 , and free-surface velocity of 100 μm thick aluminum with 100 μm CH foil at the front got 2.87 km/s with laser intensity 7.28 x 10 11 W·cm -2 . (authors)

  4. Copernicus observations of Iota Herculis velocity variations

    Science.gov (United States)

    Rogerson, J. B., Jr.

    1984-01-01

    Observations of Iota Her at 109.61-109.67 nm obtained with the U1 channel of the Copernicus spectrophotometer at resolution 5 pm during 3.6 days in May, 1979, are reported. Radial-velocity variations are detected and analyzed as the sum of two sinusoids with frequencies 0.660 and 0.618 cycles/day and amplitudes 9.18 and 8.11 km/s, respectively. Weak evidence supporting the 13.9-h periodicity seen in line-profile variations by Smith (1978) is found.

  5. Doppler Velocity Signatures of Idealized Elliptical Vortices

    Directory of Open Access Journals (Sweden)

    Wen-Chau Lee

    2006-01-01

    Full Text Available Doppler radar observations have revealed a class of atmospheric vortices (tropical cyclones, tornadoes, dust devils that possess elliptical radar reflectivity signatures. One famous example is Typhoon Herb (1996 that maintained its elliptical reflectivity structure over a 40-hour period. Theoretical work and dual-Doppler analyses of observed tropical cyclones have suggested two physical mechanisms that can explain the formation of two types of elliptical vortices observed in nature, namely, the combination of a circular vortex with either a wavenumber two vortex Rossby wave or a deformation field. The characteristics of these two types of elliptical vortices and their corresponding Doppler velocity signatures have not been previously examined.

  6. Acoustic methods for measuring bullet velocity

    OpenAIRE

    Courtney, Michael

    2008-01-01

    This article describes two acoustic methods to measure bullet velocity with an accuracy of 1% or better. In one method, a microphone is placed within 0.1 m of the gun muzzle and a bullet is fired at a steel target 45 m away. The bullet's flight time is the recorded time between the muzzle blast and sound of hitting the target minus the time for the sound to return from the target to the microphone. In the other method, the microphone is placed equidistant from both the gun muzzle and the stee...

  7. Consideration of Wear Rates at High Velocity

    Science.gov (United States)

    2010-03-01

    materials, Type 304 stainless steel, molybdenum, vanadium, SAE 4140 steel, and tantalum, were evaluated at 835, 1200, and 2500 ft/s. Track conditions...the exception that the pin was replaced by a restrained spherical rider (ball). The 6.35 mm diameter balls were made of SAE 1095 steel and the disk was... SAE 1020 steel. Sliding velocity and applied load ranged from 0.254–33.5 m/s and 745 MPa–1.76 GPa, respectively. Figure 1.8 shows the effect of

  8. Boundary layer heights derived from velocity spectra

    Energy Technology Data Exchange (ETDEWEB)

    Hoejstrup, J.; Barthelmie, R.J. [Risoe National Lab., Roskilde (Denmark); Kaellstrand, B. [Univ. of Uppsala, Uppsala (Sweden)

    1997-10-01

    It is a well-known fact that the height of the mixed layer determines the size of the largest and most energetic eddies that can be observed in the unstable boundary layer, and consequently a peak can be observed in the power spectra of the along-wind velocity component at scales comparable to the mixed layer depth. We will now show how the mixed layer depth can be derived from the u-specta and the results will be compared with direct measurements using pibal and tethersonde measurements. (au)

  9. Size and velocity measurements in combustion systems

    International Nuclear Information System (INIS)

    Levy, Y.; Timnat, Y.M.

    1986-01-01

    Two-phase flow measurements for size and velocity determination in combustion systems are discussed: the pedestal technique and phase Doppler anemometry (PDA) are described in detail. The experimental apparatus for the pedestal method includes the optical laser-Doppler anemometry (LDA) package and the electronic data acquisition system. The latter comprises three channels for recording the Doppler frequency, and the pedestal amplitude as well as the validation pulse. Results of measurements performed in a dump combustor, into which kerosene droplets were injected, are presented. The principle of the PDA technique is explained and validation experiments, using latex particles, are reported. Finally the two methods are compared

  10. Topics in random walks in random environment

    International Nuclear Information System (INIS)

    Sznitman, A.-S.

    2004-01-01

    Over the last twenty-five years random motions in random media have been intensively investigated and some new general methods and paradigms have by now emerged. Random walks in random environment constitute one of the canonical models of the field. However in dimension bigger than one they are still poorly understood and many of the basic issues remain to this day unresolved. The present series of lectures attempt to give an account of the progresses which have been made over the last few years, especially in the study of multi-dimensional random walks in random environment with ballistic behavior. (author)

  11. Effects of combined aerobic and resistance exercise on central arterial stiffness and gait velocity in patients with chronic poststroke hemiparesis.

    Science.gov (United States)

    Lee, Yong Hee; Park, Soo Hyun; Yoon, Eun Sun; Lee, Chong-Do; Wee, Sang Ouk; Fernhall, Bo; Jae, Sae Young

    2015-09-01

    The effects of combined aerobic and resistance exercise training on central arterial stiffness and gait velocity in patients with chronic poststroke hemiparesis were investigated. Twenty-six patients with chronic poststroke hemiparesis were randomly assigned to either the combined aerobic and resistance exercise group (n = 14) or the control group (n = 12). The exercise intervention group received a combined aerobic and resistance exercise training (1 hr/day, three times/week for 16 wks), whereas the control group received usual care. Central arterial stiffness was determined by pulse wave velocity and augmentation index. Gait velocity was assessed using the 6-min walk test, 10-m walk test, and the Timed Up-and-Go test. Patients in the exercise intervention group had greater improvement of mean pulse wave velocity (P hemiparesis.

  12. Clinical longitudinal standards for height, weight, height velocity, weight velocity, and stages of puberty.

    Science.gov (United States)

    Tanner, J M; Whitehouse, R H

    1976-01-01

    New charts for height, weight, height velocity, and weight velocity are presented for clinical (as opposed to population survey) use. They are based on longitudinal-type growth curves, using the same data as in the British 1965 growth standards. In the velocity standards centiles are given for children who are early- and late-maturing as well as for those who mature at the average age (thus extending the use of the previous charts). Limits of normality for the age of occurrence of the adolescent growth spurt are given and also for the successive stages of penis, testes, and pubic hair development in boys, and for stages of breast and pubic hair development in girls. PMID:952550

  13. Velocity Dependence of Friction of Confined Hydrocarbons

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    2010-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon “polymer” solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence of the f......We present molecular dynamics friction calculations for confined hydrocarbon “polymer” solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence...... of the frictional shear stress for both cases. In our simulations, the polymer films are very thin (∼3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature...... in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all...

  14. Rotational velocities of low-mass stars

    International Nuclear Information System (INIS)

    Stauffer, J.B.; Hartmann, L.W.; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA)

    1986-01-01

    The rotational velocities of stars provide important clues to how stars form and evolve. Yet until recently, studies of stellar rotation were limited to stars more massive than the sun. This is beginning to change, and an observational outline of the rotational velocity evolution of stars less massive than the sun can now be provided. Low-mass stars rotate slowly during the early stages of premain-sequence evolution, and spin up as they contract to the main sequence. This spin-up culminates in a brief period of very rapid rotation at an age of order 50 million years. Physical interpretation of this increase in rotation and the subsequent main-sequence spin-down are complicated by the possibility of differential internal rotation. The observed rapidity of spin-down among G dwarfs suggests that initially only the outer convective envelopes of these stars are slowed. The data suggest an intrinsic spread in angular momentum among young stars of the same mass and age, a spread which is apparently minimized by the angular-momentum loss mechanism in old low-mass stars. 83 references

  15. Turbulent structure of thermal plume. Velocity field

    International Nuclear Information System (INIS)

    Guillou, B.; Brahimi, M.; Doan-kim-son

    1986-01-01

    An experimental investigation and a numerical study of the dynamics of a turbulent plume rising from a strongly heated source are described. This type of flow is met in thermal effluents (air, vapor) from, e.g., cooling towers of thermal power plants. The mean and fluctuating values of the vertical component of the velocity were determined using a Laser-Doppler anemometer. The measurements allow us to distinguish three regions in the plume-a developing region near the source, an intermediate region, and a self-preserving region. The characteristics of each zone have been determined. In the self-preserving zone, especially, the turbulence level on the axis and the entrainment coefficient are almost twice of the values observed in jets. The numerical model proposed takes into account an important phenomenon, the intermittency, observed in the plume. This model, established with the self-preserving hypothesis, brings out analytical laws. These laws and the predicted velocity profile are in agreement with the experimental evolutions [fr

  16. Neoclassical rotation velocities in multispecies plasmas

    International Nuclear Information System (INIS)

    Houlberg, W.A.; Hirshman, S.P.; Shaing, K.C.

    1996-01-01

    We examine the relationships between the poloidal, toroidal and parallel rotation velocities for typical plasma conditions in existing tokamak experiments. The radial force balance, neoclassical solution to the poloidal flow from the parallel force balance, and anomalous toroidal rotation axe included. A full multispecies formulation of the neoclassical transport theory is implemented in the NCLASS code (which includes arbitrary axisymmetric geometries and plasma collisionalities) to determine the poloidal rotation velocities. Comparisons are made with analytic relationships derived from a single impurity formulation of the problem. The roles of the radial electric field and species density and pressure gradients are evaluated. The determination of the radial electric field using the NCLASS solution for poloidal rotation and a local measurement of the toroidal rotation in conjunction with measured plasma profiles is discussed; it has been used in analysis of TFTR enhanced reverse shear plasmas. The ordering of banana orbit size small relative to local minor radius and gradients (as incorporated into initial versions of NCLASS) are examined for typical negative shear plasmas. We show the degree to which these constraints axe violated and demonstrate that finite orbit corrections axe required for better determination of the bootstrap current, particle fluxes and ion heat fluxes, i.e., the conditions r much-lt Δ b much-lt r n , r T , r E are significantly violated. Progress in relaxing these constraints is discussed

  17. THE NIRSPEC ULTRACOOL DWARF RADIAL VELOCITY SURVEY

    International Nuclear Information System (INIS)

    Blake, Cullen H.; Charbonneau, David; White, Russel J.

    2010-01-01

    We report the results of an infrared Doppler survey designed to detect brown dwarf and giant planetary companions to a magnitude-limited sample of ultracool dwarfs. Using the NIRSPEC spectrograph on the Keck II telescope, we obtained approximately 600 radial velocity (RV) measurements over a period of six years of a sample of 59 late-M and L dwarfs spanning spectral types M8/L0 to L6. A subsample of 46 of our targets has been observed on three or more epochs. We rely on telluric CH 4 absorption features in Earth's atmosphere as a simultaneous wavelength reference and exploit the rich set of CO absorption features found in the K-band spectra of cool stars and brown dwarfs to measure RVs and projected rotational velocities. For a bright, slowly rotating M dwarf standard we demonstrate an RV precision of 50 m s -1 and for slowly rotating L dwarfs we achieve a typical RV precision of approximately 200 m s -1 . This precision is sufficient for the detection of close-in giant planetary companions to mid-L dwarfs as well as more equal mass spectroscopic binary systems with small separations (a +0.7 -0.6 Gyr, similar to that of nearby sun-like stars. We simulate the efficiency with which we detect spectroscopic binaries and find that the rate of tight (a +8.6 -1.6 %, consistent with recent estimates in the literature of a tight binary fraction of 3%-4%.

  18. Bulk velocity extraction for nano-scale Newtonian flows

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenfei, E-mail: zwenfei@gmail.com [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China); Sun, Hongyu [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China)

    2012-04-16

    The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

  19. Bulk velocity extraction for nano-scale Newtonian flows

    International Nuclear Information System (INIS)

    Zhang, Wenfei; Sun, Hongyu

    2012-01-01

    The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

  20. Plasma flow velocity measurements using a modulated Michelson interferometer

    International Nuclear Information System (INIS)

    Howard, J.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (orig.)

  1. Daily dialysis reduces pulse wave velocity in chronic hemodialysis patients.

    Science.gov (United States)

    Di Micco, Lucia; Torraca, Serena; Sirico, Maria Luisa; Tartaglia, Domenico; Di Iorio, Biagio

    2012-05-01

    Pulse wave velocity (PWV) is a predictor of morbidity and mortality in patients with end-stage renal disease (ESRD). Dialysis patients show cyclic changes in PWV related to their hydration status and blood pressure. Our aim is to assess the impact of daily dialysis on PWV. We performed a randomized crossover study of 60 patients who underwent standard hemodialysis (HD) three times per week for at least 6 months. Patients were classified into three groups according to their PWV values before (pre-) and after (post-) HD, with a cutoff value of 12 m s(-1), as follows: the low-low (LL) group had normal pre-HD and post-HD PWV; the high-low (HL) group had high pre-HD PWV and normal post-HD PWV; and the high-high (HH) group had high pre- and post-HD PWV. All patients continued standard HD for 2 weeks. A total of 10 patients from each group were randomly assigned to continue standard HD for 1 week and then underwent daily dialysis for 1 week. The remaining 10 patients underwent daily dialysis for 1 week and then underwent standard HD for 1 week. PWV values were measured before and 1 h after each dialysis session. With daily dialysis treatment, 2 of 20 patients (10%) moved from the PWV-HH group to the PWV-HL group, whereas 18 of 20 patients (90%) moved from the PWV-HL group to the PWV-LL group (P = 0.030). Daily dialysis reduces PWV in the ESRD patients. As PWV is a strong predictor of mortality in ESRD and has cyclic variations in patients who are on standard HD, we believe that daily dialysis may be used in patients with high PWV levels to reduce their mortality risk.

  2. Validation of Transverse Oscillation Vector Velocity Estimation In-Vivo

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Thomsen, Carsten

    2007-01-01

    Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound (US) beam direction. This implies that a Doppler angle under examination close to 90deg results in unreliable information about the true blood direction and blood velocity. The novel...... the presented angle independent 2-D vector velocity method. The results give reason to believe that the TO method can be a useful alternative to conventional Doppler systems bringing forth new information to the US examination of blood flow....

  3. Direct Investigation of Velocity Overshoot in the Femtosecond Regime

    Science.gov (United States)

    1990-01-25

    by block nuinber) The experiental study ofsubpicsecond transport in GaAs and other semionductors is of fundmental inPortanoe for the understanding of...velocities, hence in principle this measurement can yield information about velocity 5 overshoot phenomenon. An electric field will modify photon absorption in...3.1.2 are the best fit of the theory assuming a constant electron velocity. The constant-velocity model cannot account for the data at 14 and 22kV/cm

  4. Quantification of aortic regurgitation by magnetic resonance velocity mapping

    DEFF Research Database (Denmark)

    Søndergaard, Lise; Lindvig, K; Hildebrandt, P

    1993-01-01

    The use of magnetic resonance (MR) velocity mapping in the quantification of aortic valvular blood flow was examined in 10 patients with angiographically verified aortic regurgitation. MR velocity mapping succeeded in identifying and quantifying the regurgitation in all patients, and the regurgit......The use of magnetic resonance (MR) velocity mapping in the quantification of aortic valvular blood flow was examined in 10 patients with angiographically verified aortic regurgitation. MR velocity mapping succeeded in identifying and quantifying the regurgitation in all patients...

  5. A stochastic differential equation framework for the turbulent velocity field

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Schmiegel, Jürgen

    We discuss a stochastic differential equation, as a modelling framework for the turbulent velocity field, that is capable of capturing basic stylized facts of the statistics of velocity increments. In particular, we focus on the evolution of the probability density of velocity increments...

  6. Thermal particle image velocity estimation of fire plume flow

    Science.gov (United States)

    Xiangyang Zhou; Lulu Sun; Shankar Mahalingam; David R. Weise

    2003-01-01

    For the purpose of studying wildfire spread in living vegetation such as chaparral in California, a thermal particle image velocity (TPIV) algorithm for nonintrusively measuring flame gas velocities through thermal infrared (IR) imagery was developed. By tracing thermal particles in successive digital IR images, the TPIV algorithm can estimate the velocity field in a...

  7. Examples of in-vivo blood vector velocity estimation

    DEFF Research Database (Denmark)

    Udesen, Jesper; Nielsen, Michael Bachmann; Nielsen, Kristian R.

    2007-01-01

    In this paper examples of in-vivo blood vector velocity images of the carotid artery are presented. The transverse oscillation (TO) method for blood vector velocity estimation has been used to estimate the vector velocities and the method is first evaluated in a circulating flowrig where...

  8. 14 CFR 29.87 - Height-velocity envelope.

    Science.gov (United States)

    2010-01-01

    ... Category A engine isolation requirements, the height-velocity envelope for complete power failure must be... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Height-velocity envelope. 29.87 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Performance § 29.87 Height-velocity envelope. (a...

  9. Response functions for infinite fermion systems with velocity dependent interactions

    International Nuclear Information System (INIS)

    Garcia-Recio, C.; Salcedo, L.L.; Navarro, J.; Nguyen Van Giai

    1991-01-01

    Response functions of infinite Fermi systems are studied in the framework of the self-consistent Random Phase Approximation. Starting from an effective interaction with velocity and density dependence, or equivalently from a local energy density functional, algebraic expressions for the RPA response function are derived. Simple formulae for the energy-weighted and polarizability sum rules are obtained. The method is illustrated by applications to nuclear matter and liquid 3 He. In nuclear matter, it is shown that existing Skyrme interactions give spin-isospin response functions close to those calculated with finite range interactions. The different renormalization of longitudinal and transverse Coulomb sum rules in nuclear matter is discussed. In 3 He, the low-lying collective spin oscillation can be well described in a wide range of momenta with a Skyrme-type interaction if the relevant Landau parameters are fitted. For the high-lying density oscillation, the introduction of a finite range term in the energy functional improves considerably the agreement with the data. (author) 54 refs., 19 figs., 4 tabs

  10. Velocity Drives Greater Power Observed During Back Squat Using Cluster Sets.

    Science.gov (United States)

    Oliver, Jonathan M; Kreutzer, Andreas; Jenke, Shane C; Phillips, Melody D; Mitchell, Joel B; Jones, Margaret T

    2016-01-01

    This investigation compared the kinetics and kinematics of cluster sets (CLU) and traditional sets (TRD) during back squat in trained (RT) and untrained (UT) men. Twenty-four participants (RT = 12, 25 ± 1 year, 179.1 ± 2.2 cm, 84.6 ± 2.1 kg; UT = 12, 25 ± 1 year, 180.1 ± 1.8 cm, 85.4 ± 3.8 kg) performed TRD (4 × 10, 120-second rest) and CLU (4 × (2 × 5) 30 seconds between clusters; 90 seconds between sets) with 70% one repetition maximum, randomly. Kinematics and kinetics were sampled through force plate and linear position transducers. Resistance-trained produced greater overall force, velocity, and power; however, similar patterns were observed in all variables when comparing conditions. Cluster sets produced significantly greater force in isolated repetitions in sets 1-3, while consistently producing greater force due to a required reduction in load during set 4 resulting in greater total volume load (CLU, 3302.4 ± 102.7 kg; TRD, 3274.8 ± 102.8 kg). Velocity loss was lessened in CLU resulting in significantly higher velocities in sets 2 through 4. Furthermore, higher velocities were produced by CLU during later repetitions of each set. Cluster sets produced greater power output for an increasing number of repetitions in each set (set 1, 5 repetitions; sets 2 and 3, 6 repetitions; set 4, 8 repetitions), and the difference between conditions increased over subsequent sets. Time under tension increased over each set and was greater in TRD. This study demonstrates greater power output is driven by greater velocity when back squatting during CLU; therefore, velocity may be a useful measure by which to assess power.

  11. Velocity dependence of friction of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, V.N.; Persson, B.N.J.

    2009-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate, and (b) polymer sliding on polymer. We discuss the velocity dependence of the frictional...... shear stress for both cases. In our simulations, the polymer films are very thin (approx. 3 nm), and the solid walls are connected to a thermostat at a short distance from the polymer slab. Under these circumstances we find that frictional heating effects are not important, and the effective temperature...... in the polymer film is always close to the thermostat temperature. In the first setup (a), for hydrocarbons with molecular lengths from 60 to 1400 carbon atoms, the shear stresses are nearly independent of molecular length, but for the shortest hydrocarbon C20H42 the frictional shear stress is lower. In all...

  12. Velocity correlations in laboratory insect swarms

    Science.gov (United States)

    Ni, R.; Ouellette, N. T.

    2015-12-01

    In contrast to animal groups such as bird flocks or migratory herds that display net, directed motion, insect swarms do not possess global order. Without such order, it is difficult to define and characterize the transition to collective behavior in swarms; nevertheless, visual observation of swarms strongly suggests that swarming insects do behave collectively. It has recently been suggested that correlation rather than order is the hallmark of emergent collective behavior. Here, we report measurements of spatial velocity correlation functions in laboratory mating swarms of the non-biting midge Chironomus riparius. Although we find some correlation at short distances, our swarms are in general only weakly correlated, in contrast to what has been observed in field studies. Our results hint at the potentially important role of environmental conditions on collective behavior, and suggest that general indicators of the collective nature of swarming are still needed.

  13. The radial velocity variations in IC 418

    International Nuclear Information System (INIS)

    Mendez, R.H.; Verga, A.D.

    1981-01-01

    The observations presented are part of a search for spectral and radial velocity variations among central stars of planetary nebulae and include the following new data: 1) Weak, previously undetected C III emissions are visible at 4056, 4186, 4516, 5270 and 5826 A. The famous unidentified emissions at 4485 and 4503 A were also found. 2) The He I absorptions at 4471 and 5875 A are blue-shifted relative to the nebular emissions. The same happens with Hsub(delta) and Hsub(γ), although in this case the shift can be at least partly attributed to blends with the strong He II absorptions, which are estimated to contribute about one half of the equivalent width at Hsub(delta) and Hsub(γ). 3) O III 5592 and C IV 5801, 5811 are also found in absorption. (Auth.)

  14. Estimation of pore pressure from seismic velocities

    International Nuclear Information System (INIS)

    Perez, Zayra; Ojeda, German Y; Mateus, Darwin

    2009-01-01

    On pore pressure calculations it is common to obtain a profile in a well bore, which is then extrapolated toward offset wells. This practice might generate mistakes on pore pressure measurements, since geological conditions may change from a well bore to another, even into the same basin. Therefore, it is important to use other tools which allow engineers not only to detect and estimate in an indirect way overpressure zones, but also to keep a lateral tracking of possible changes that may affect those values in the different formations. Taking into account this situation, we applied a methodology that estimates formation pressure from 3D seismic velocities by using the Eaton method. First, we estimated formation pore pressure; then, we identified possible overpressure zones. Finally, those results obtained from seismic information were analyzed involving well logs and pore pressure tests, in order to compare real data with prediction based on seismic information from the Colombian foothill.

  15. Velocity slice imaging for dissociative electron attachment

    Science.gov (United States)

    Nandi, Dhananjay; Prabhudesai, Vaibhav S.; Krishnakumar, E.; Chatterjee, A.

    2005-05-01

    A velocity slice imaging method is developed for measuring the angular distribution of fragment negative ions arising from dissociative electron attachment (DEA) to molecules. A low energy pulsed electron gun, a pulsed field ion extraction, and a two-dimensional position sensitive detector consisting of microchannel plates and a wedge-and-strip anode are used for this purpose. Detection and storage of each ion separately for its position and flight time allows analysis of the data offline for any given time slice, without resorting to pulsing the detector bias. The performance of the system is evaluated by measuring the angular distribution of O- from O2 and comparing it with existing data obtained using conventional technique. The capability of this technique in obtaining forward and backward angular distribution data is shown to have helped in resolving one of the existing problems in the electron scattering on O2.

  16. Rogue events in the group velocity horizon.

    Science.gov (United States)

    Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Mahnke, Christoph; Mitschke, Fedor; Steinmeyer, Günter

    2012-01-01

    The concept of rogue waves arises from a mysterious and potentially calamitous phenomenon of oceanic surfaces. There is mounting evidence that they are actually commonplace in a variety of different physical settings. A set of defining criteria has been advanced; this set is of great generality and therefore applicable to a wide class of systems. The question arises naturally whether there are generic mechanisms responsible for extreme events in different systems. Here we argue that under suitable circumstances nonlinear interaction between weak and strong waves results in intermittent giant waves with all the signatures of rogue waves. To obtain these circumstances only a few basic conditions must be met. Then reflection of waves at the so-called group-velocity horizon occurs. The connection between rogue waves and event horizons, seemingly unrelated physical phenomena, is identified as a feature common in many different physical systems.

  17. Stationary velocity distributions in traffic flows

    International Nuclear Information System (INIS)

    1997-01-01

    We introduce a traffic flow model that incorporates clustering and passing. We obtain analytically the steady state characteristics of the flow from a Boltzmann-like equation. A single dimensionless parameter, R=c 0 v 0 t 0 with c 0 the concentration, v 0 the velocity range, and t 0 -1 the passing rate, determines the nature of the steady state. When R 1, large clusters with average mass left-angle m right-angle ∼R α form, and the flux is J∼R -γ . The initial distribution of slow cars governs the statistics. When P 0 (v)∼v μ as v→0, the scaling exponents are γ=1/(μ+2), α=1/2 when μ>0, and α=(μ+1)/(μ+2) when μ<0. copyright 1997 The American Physical Society

  18. Railgun armature velocity improvement, SBIR phase 2

    Science.gov (United States)

    Thurmond, Leo E.; Bauer, David P.

    1992-08-01

    Railgun hypervelocity performance has not been repeatably demonstrated at velocities over 6 km/s. A significant performance limiting phenomena is the formation of secondary current paths in parallel with the main projectile accelerating plasma. A confined plasma armature technique was developed to prevent secondary armature formation. Confinement prevents loss of ionized material from the plasma armature and thereby prevents formation of a low rail-to-rail conductance. We controlled pressure in the confined armature via controlled venting through ports in the rails. Railgun tests with the confined armature show that sealing at the rail-confinement vessel interface is critical and difficult to achieve. Our tests show that during low seal leakage operation secondaries are prevented. However, maintaining good seal for the entire launch is very difficult.

  19. Ultrasonic Doppler Velocity Profiler for Fluid Flow

    CERN Document Server

    2012-01-01

    The ultrasonic velocity profile (UVP) method, first developed in medical engineering, is now widely used in clinical settings. The fluid mechanical basis of UVP was established in investigations by the author and his colleagues with work demonstrating that UVP is a powerful new tool in experimental fluid mechanics. There are diverse examples, ranging from problems in fundamental fluid dynamics to applied problems in mechanical, chemical, nuclear, and environmental engineering. In all these problems, the methodological principle in fluid mechanics was converted from point measurements to spatio-temporal measurements along a line. This book is the first monograph on UVP that offers comprehensive information about the method, its principles, its practice, and applied examples, and which serves both current and new users. Current users can confirm that their application configurations are correct, which will help them to improve the configurations so as to make them more efficient and effective. New users will be...

  20. Formulating viscous hydrodynamics for large velocity gradients

    International Nuclear Information System (INIS)

    Pratt, Scott

    2008-01-01

    Viscous corrections to relativistic hydrodynamics, which are usually formulated for small velocity gradients, have recently been extended from Navier-Stokes formulations to a class of treatments based on Israel-Stewart equations. Israel-Stewart treatments, which treat the spatial components of the stress-energy tensor τ ij as dynamical objects, introduce new parameters, such as the relaxation times describing nonequilibrium behavior of the elements τ ij . By considering linear response theory and entropy constraints, we show how the additional parameters are related to fluctuations of τ ij . Furthermore, the Israel-Stewart parameters are analyzed for their ability to provide stable and physical solutions for sound waves. Finally, it is shown how these parameters, which are naturally described by correlation functions in real time, might be constrained by lattice calculations, which are based on path-integral formulations in imaginary time

  1. The effects of Kinesiotaping on quadriceps muscle performance at different velocities : A randomized controlled trial

    NARCIS (Netherlands)

    Guedes, Rogerio; Bottaro, Martim; Magalhães, Igor; Trindade, Matheus; Brown, Lee E.; Carmo, Jake Do; Carregaro, Rodrigo Luiz

    2016-01-01

    BACKGROUND: Kinesiotaping (KT) has become popular among athletic trainers and physical therapists. Most of KT studies investigated only the immediate responses, and only a few evaluated the long-term effects. OBJECTIVES: To evaluate the effects of 48 hours of KT on knee extensor performance of

  2. Simultaneous Range-Velocity Processing and SNR Analysis of AFIT’s Random Noise Radar

    Science.gov (United States)

    2012-03-22

    reducing the overall processing time. Two computers, equipped with NVIDIA ® GPUs, were used to process the col- 45 lected data. The specifications for each...gather the results back to the CPU. Another company , AccelerEyes®, has developed a product called Jacket® that claims to be better than the parallel...Number of Processing Cores 4 8 Processor Speed 3.33 GHz 3.07 GHz Installed Memory 48 GB 48 GB GPU Make NVIDIA NVIDIA GPU Model Tesla 1060 Tesla C2070 GPU

  3. A Simple Piece of Apparatus to Aid the Understanding of the Relationship between Angular Velocity and Linear Velocity

    Science.gov (United States)

    Unsal, Yasin

    2011-01-01

    One of the subjects that is confusing and difficult for students to fully comprehend is the concept of angular velocity and linear velocity. It is the relationship between linear and angular velocity that students find difficult; most students understand linear motion in isolation. In this article, we detail the design, construction and…

  4. Global catalog of earthquake rupture velocities shows anticorrelation between stress drop and rupture velocity

    Science.gov (United States)

    Chounet, Agnès; Vallée, Martin; Causse, Mathieu; Courboulex, Françoise

    2018-05-01

    Application of the SCARDEC method provides the apparent source time functions together with seismic moment, depth, and focal mechanism, for most of the recent earthquakes with magnitude larger than 5.6-6. Using this large dataset, we have developed a method to systematically invert for the rupture direction and average rupture velocity Vr, when unilateral rupture propagation dominates. The approach is applied to all the shallow (z earthquakes of the catalog over the 1992-2015 time period. After a careful validation process, rupture properties for a catalog of 96 earthquakes are obtained. The subsequent analysis of this catalog provides several insights about the seismic rupture process. We first report that up-dip ruptures are more abundant than down-dip ruptures for shallow subduction interface earthquakes, which can be understood as a consequence of the material contrast between the slab and the overriding crust. Rupture velocities, which are searched without any a-priori up to the maximal P wave velocity (6000-8000 m/s), are found between 1200 m/s and 4500 m/s. This observation indicates that no earthquakes propagate over long distances with rupture velocity approaching the P wave velocity. Among the 23 ruptures faster than 3100 m/s, we observe both documented supershear ruptures (e.g. the 2001 Kunlun earthquake), and undocumented ruptures that very likely include a supershear phase. We also find that the correlation of Vr with the source duration scaled to the seismic moment (Ts) is very weak. This directly implies that both Ts and Vr are anticorrelated with the stress drop Δσ. This result has implications for the assessment of the peak ground acceleration (PGA) variability. As shown by Causse and Song (2015), an anticorrelation between Δσ and Vr significantly reduces the predicted PGA variability, and brings it closer to the observed variability.

  5. Accelerated radial Fourier-velocity encoding using compressed sensing

    International Nuclear Information System (INIS)

    Hilbert, Fabian; Han, Dietbert

    2014-01-01

    Purpose:Phase Contrast Magnetic Resonance Imaging (MRI) is a tool for non-invasive determination of flow velocities inside blood vessels. Because Phase Contrast MRI only measures a single mean velocity per voxel, it is only applicable to vessels significantly larger than the voxel size. In contrast, Fourier Velocity Encoding measures the entire velocity distribution inside a voxel, but requires a much longer acquisition time. For accurate diagnosis of stenosis in vessels on the scale of spatial resolution, it is important to know the velocity distribution of a voxel. Our aim was to determine velocity distributions with accelerated Fourier Velocity Encoding in an acquisition time required for a conventional Phase Contrast image. Materials and Methods:We imaged the femoral artery of healthy volunteers with ECG - triggered, radial CINE acquisition. Data acquisition was accelerated by undersampling, while missing data were reconstructed by Compressed Sensing. Velocity spectra of the vessel were evaluated by high resolution Phase Contrast images and compared to spectra from fully sampled and undersampled Fourier Velocity Encoding. By means of undersampling, it was possible to reduce the scan time for Fourier Velocity Encoding to the duration required for a conventional Phase Contrast image. Results:Acquisition time for a fully sampled data set with 12 different Velocity Encodings was 40 min. By applying a 12.6 - fold retrospective undersampling, a data set was generated equal to 3:10 min acquisition time, which is similar to a conventional Phase Contrast measurement. Velocity spectra from fully sampled and undersampled Fourier Velocity Encoded images are in good agreement and show the same maximum velocities as compared to velocity maps from Phase Contrast measurements. Conclusion: Compressed Sensing proved to reliably reconstruct Fourier Velocity Encoded data. Our results indicate that Fourier Velocity Encoding allows an accurate determination of the velocity

  6. The effect of fog on radionuclide deposition velocities

    International Nuclear Information System (INIS)

    Gibb, R.; Carson, P.; Thompson, W.

    1997-01-01

    Current nuclear power station release models do not evaluate deposition under foggy atmospheric conditions. Deposition velocities and scavenging coefficients of radioactive particles entrained in fog are presented for the Point Lepreau area of the Bay of Fundy coast. It is recommended to calculate deposition based on fog deposition velocities. The deposition velocities can be calculated from common meteorological data. The range of deposition velocities is approximately 1 - 100 cm/s. Fog deposition is surface roughness dependent with forests having larger deposition and deposition velocities than soil or grasses. (author)

  7. A new method for measurement of granular velocities

    International Nuclear Information System (INIS)

    Nyborg Andersen, B.

    1984-01-01

    A new, supplementary method to measure granular velocities is presented. The method utilizes the Doppler shift caused by the line of sight component of the solar rotation to cause a wavelength shift through spectral lines as function of heliocentric angle. By measuring the center-to-limb variation of the granular intensity fluctations at different wavelength positions in the lines, the velocities are found. To do this, assumptions regarding the geometrical structure of the velocity and intensity fields have to be made. Preliminary application of the method results in a steep velocity gradient suggesting zero velocity at a hight of 200 km above tau 500 = 1. Possible causes are discussed

  8. A new estimator for vector velocity estimation [medical ultrasonics

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2001-01-01

    A new estimator for determining the two-dimensional velocity vector using a pulsed ultrasound field is derived. The estimator uses a transversely modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation...... be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce the influence of a spatial velocity spread. Examples for different velocity vectors and field conditions are shown using both simple and more complex field simulations. A relative accuracy of 10.1% is obtained...

  9. Analyses of Current And Wave Forces on Velocity Caps

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Buhrkall, Jeppe; Eskesen, Mark C. D.

    2015-01-01

    Velocity caps are often used in connection with for instance offshore intake sea water for the use of for cooling water for power plants or as a source for desalinization plants. The intakes can also be used for river intakes. The velocity cap is placed on top of a vertical pipe. The vertical pipe......) this paper investigates the current and wave forces on the velocity cap and the vertical cylinder. The Morison’s force model was used in the analyses of the extracted force time series in from the CFD model. Further the distribution of the inlet velocities around the velocity cap was also analyzed in detail...

  10. Accelerated radial Fourier-velocity encoding using compressed sensing

    Energy Technology Data Exchange (ETDEWEB)

    Hilbert, Fabian; Han, Dietbert [Wuerzburg Univ. (Germany). Inst. of Radiology; Wech, Tobias; Koestler, Herbert [Wuerzburg Univ. (Germany). Inst. of Radiology; Wuerzburg Univ. (Germany). Comprehensive Heart Failure Center (CHFC)

    2014-10-01

    Purpose:Phase Contrast Magnetic Resonance Imaging (MRI) is a tool for non-invasive determination of flow velocities inside blood vessels. Because Phase Contrast MRI only measures a single mean velocity per voxel, it is only applicable to vessels significantly larger than the voxel size. In contrast, Fourier Velocity Encoding measures the entire velocity distribution inside a voxel, but requires a much longer acquisition time. For accurate diagnosis of stenosis in vessels on the scale of spatial resolution, it is important to know the velocity distribution of a voxel. Our aim was to determine velocity distributions with accelerated Fourier Velocity Encoding in an acquisition time required for a conventional Phase Contrast image. Materials and Methods:We imaged the femoral artery of healthy volunteers with ECG - triggered, radial CINE acquisition. Data acquisition was accelerated by undersampling, while missing data were reconstructed by Compressed Sensing. Velocity spectra of the vessel were evaluated by high resolution Phase Contrast images and compared to spectra from fully sampled and undersampled Fourier Velocity Encoding. By means of undersampling, it was possible to reduce the scan time for Fourier Velocity Encoding to the duration required for a conventional Phase Contrast image. Results:Acquisition time for a fully sampled data set with 12 different Velocity Encodings was 40 min. By applying a 12.6 - fold retrospective undersampling, a data set was generated equal to 3:10 min acquisition time, which is similar to a conventional Phase Contrast measurement. Velocity spectra from fully sampled and undersampled Fourier Velocity Encoded images are in good agreement and show the same maximum velocities as compared to velocity maps from Phase Contrast measurements. Conclusion: Compressed Sensing proved to reliably reconstruct Fourier Velocity Encoded data. Our results indicate that Fourier Velocity Encoding allows an accurate determination of the velocity

  11. Accelerated radial Fourier-velocity encoding using compressed sensing.

    Science.gov (United States)

    Hilbert, Fabian; Wech, Tobias; Hahn, Dietbert; Köstler, Herbert

    2014-09-01

    Phase Contrast Magnetic Resonance Imaging (MRI) is a tool for non-invasive determination of flow velocities inside blood vessels. Because Phase Contrast MRI only measures a single mean velocity per voxel, it is only applicable to vessels significantly larger than the voxel size. In contrast, Fourier Velocity Encoding measures the entire velocity distribution inside a voxel, but requires a much longer acquisition time. For accurate diagnosis of stenosis in vessels on the scale of spatial resolution, it is important to know the velocity distribution of a voxel. Our aim was to determine velocity distributions with accelerated Fourier Velocity Encoding in an acquisition time required for a conventional Phase Contrast image. We imaged the femoral artery of healthy volunteers with ECG-triggered, radial CINE acquisition. Data acquisition was accelerated by undersampling, while missing data were reconstructed by Compressed Sensing. Velocity spectra of the vessel were evaluated by high resolution Phase Contrast images and compared to spectra from fully sampled and undersampled Fourier Velocity Encoding. By means of undersampling, it was possible to reduce the scan time for Fourier Velocity Encoding to the duration required for a conventional Phase Contrast image. Acquisition time for a fully sampled data set with 12 different Velocity Encodings was 40 min. By applying a 12.6-fold retrospective undersampling, a data set was generated equal to 3:10 min acquisition time, which is similar to a conventional Phase Contrast measurement. Velocity spectra from fully sampled and undersampled Fourier Velocity Encoded images are in good agreement and show the same maximum velocities as compared to velocity maps from Phase Contrast measurements. Compressed Sensing proved to reliably reconstruct Fourier Velocity Encoded data. Our results indicate that Fourier Velocity Encoding allows an accurate determination of the velocity distribution in vessels in the order of the voxel size. Thus

  12. The Limit Deposit Velocity model, a new approach

    Directory of Open Access Journals (Sweden)

    Miedema Sape A.

    2015-12-01

    Full Text Available In slurry transport of settling slurries in Newtonian fluids, it is often stated that one should apply a line speed above a critical velocity, because blow this critical velocity there is the danger of plugging the line. There are many definitions and names for this critical velocity. It is referred to as the velocity where a bed starts sliding or the velocity above which there is no stationary bed or sliding bed. Others use the velocity where the hydraulic gradient is at a minimum, because of the minimum energy consumption. Most models from literature are one term one equation models, based on the idea that the critical velocity can be explained that way.

  13. Temperature and center-limb variations of transition region velocities

    International Nuclear Information System (INIS)

    Athay, R.G.; Dere, K.P.

    1989-01-01

    HRTS data from the Spacelab 2 mission are used to derive the center-limb and temperature variations of the mean velocity and the velocity variance in the solar chromosphere and transition zone. The mean velocity is found to vary much more rapidly from center to limb and with temperature than does the velocity variance. Also, the mean velocity shows a characteristic signature at some magnetic neutral lines in accordance with the findings of Klimchuk (1987) from Solar Maximum Mission (SMM) data. The velocity variance does not show a characteristic signature at the neutral lines but shows an inverse correlation with intensity. The latter is interpreted as reduced velocity variance in strong field regions. The results are discussed in terms of downflow along lines of force in magnetic arcades. 23 refs

  14. Maximum Likelihood Blood Velocity Estimator Incorporating Properties of Flow Physics

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Jensen, Jørgen Arendt

    2004-01-01

    )-data under investigation. The flow physic properties are exploited in the second term, as the range of velocity values investigated in the cross-correlation analysis are compared to the velocity estimates in the temporal and spatial neighborhood of the signal segment under investigation. The new estimator...... has been compared to the cross-correlation (CC) estimator and the previously developed maximum likelihood estimator (MLE). The results show that the CMLE can handle a larger velocity search range and is capable of estimating even low velocity levels from tissue motion. The CC and the MLE produce...... for the CC and the MLE. When the velocity search range is set to twice the limit of the CC and the MLE, the number of incorrect velocity estimates are 0, 19.1, and 7.2% for the CMLE, CC, and MLE, respectively. The ability to handle a larger search range and estimating low velocity levels was confirmed...

  15. Live performance of male broilers subjected to constant or increasing air velocities at moderate temperatures with a high dew point.

    Science.gov (United States)

    Dozier, W A; Lott, B D; Branton, S L

    2005-08-01

    This study examined the effects of varying air velocities vs. a constant air velocity with a cyclic temperature curve of 25-30-25 degrees C and a dew point of 23 degrees C on broilers from 28 to 49 d of age. Four replicate trials were conducted. In each trial, 742 male broilers were randomly allocated to 6 floor pens or 2 air velocity tunnels, with each tunnel consisting of 4 pens. Bird density, feeder, and waterer space were similar across all pens (53 birds/ pen; 0.07 m2/bird). The treatments were control (still air), constant air velocity of 120 m/min, and increasing air velocity (90 m/min from 28 to 35 d, 120 m/min from 36 to 42 d, and 180 m/min from 43 to 49 d). Birds grown in a still air environment gained less weight, consumed less feed, and converted feed less efficiently between 28 and 49 d than birds subjected to moving air (constant or increasing). Growth responses between the air velocity treatments were similar from 28 to 35 and 36 to 42 d of age. Increasing air velocity to 180 m/min improved (P < or = 0.02) the growth rate of broilers from 43 to 49 d of age over birds receiving an air velocity of 120 m/min, but the incidence of mortality was not affected. These results provide evidence that increasing air velocity from 120 to 180 m/min is beneficial to broilers weighing 2.5 kg or greater when exposed to moderate temperatures.

  16. Response of slow and fast muscle to hypothyroidism: maximal shortening velocity and myosin isoforms

    Science.gov (United States)

    Caiozzo, V. J.; Herrick, R. E.; Baldwin, K. M.

    1992-01-01

    This study examined both the shortening velocity and myosin isoform distribution of slow- (soleus) and fast-twitch (plantaris) skeletal muscles under hypothyroid conditions. Adult female Sprague-Dawley rats were randomly assigned to one of two groups: control (n = 7) or hypothyroid (n = 7). In both muscles, the relative contents of native slow myosin (SM) and type I myosin heavy chain (MHC) increased in response to the hypothyroid treatment. The effects were such that the hypothyroid soleus muscle expressed only the native SM and type I MHC isoforms while repressing native intermediate myosin and type IIA MHC. In the plantaris, the relative content of native SM and type I MHC isoforms increased from 5 to 13% and from 4 to 10% of the total myosin pool, respectively. Maximal shortening velocity of the soleus and plantaris as measured by the slack test decreased by 32 and 19%, respectively, in response to hypothyroidism. In contrast, maximal shortening velocity as estimated by force-velocity data decreased only in the soleus (-19%). No significant change was observed for the plantaris.

  17. Random broadcast on random geometric graphs

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory; Elsasser, Robert [UNIV OF PADERBORN; Friedrich, Tobias [ICSI/BERKELEY; Sauerwald, Tomas [ICSI/BERKELEY

    2009-01-01

    In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or the giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.

  18. Quantumness, Randomness and Computability

    International Nuclear Information System (INIS)

    Solis, Aldo; Hirsch, Jorge G

    2015-01-01

    Randomness plays a central role in the quantum mechanical description of our interactions. We review the relationship between the violation of Bell inequalities, non signaling and randomness. We discuss the challenge in defining a random string, and show that algorithmic information theory provides a necessary condition for randomness using Borel normality. We close with a view on incomputablity and its implications in physics. (paper)

  19. Deterministic nonlinear characteristics of in vivo blood flow velocity and arteriolar diameter fluctuations

    International Nuclear Information System (INIS)

    Parthimos, D; Osterloh, K; Pries, A R; Griffith, T M

    2004-01-01

    We have performed a nonlinear analysis of fluctuations in red cell velocity and arteriolar calibre in the mesenteric bed of the anaesthetized rat. Measurements were obtained under control conditions and during local superfusion with N G -nitro-L-arginine (L-NNA, 30 μM) and tetrabutylammonium (TBA, 0.1 mM), which suppress NO synthesis and block Ca 2+ activated K + channels (K Ca ), respectively. Time series were analysed by calculating correlation dimensions and largest Lyapunov exponents. Both statistics were higher for red cell velocity than diameter fluctuations, thereby potentially differentiating between global and local mechanisms that regulate microvascular flow. Evidence for underlying nonlinear structure was provided by analysis of surrogate time series generated from the experimental data following randomization of Fourier phase. Complexity indices characterizing time series under control conditions were in general higher than those derived from data obtained during superfusion with L-NNA and TBA

  20. Coexistence of Velocity Renormalization and Ferrimagnetic Fluctuation in the Organic Dirac Electron System α-(BEDT-TTF)2I3

    Science.gov (United States)

    Matsuno, Genki; Kobayashi, Akito

    2018-05-01

    We evaluate the uniform spin susceptibility in an extended Hubbard model describing α-(BEDT-TTF)2I3. Employing the Fock-type self-energy with the long-range Coulomb interaction and the random phase approximation with the on-site Coulomb interaction, it is clarified that the characteristic energy scales at which ferrimagnetic fluctuation and velocity renormalization emerge are different. This is why these phenomena coexist while the ferrimagnetic fluctuation is disturbed by the velocity renormalization. In addition, it is found that screening effect to the self-energy is irrelevant in the presence of a strong on-site Coulomb interaction U.

  1. Validity of a Commercial Linear Encoder to Estimate Bench Press 1 RM from the Force-Velocity Relationship

    OpenAIRE

    Bosquet, Laurent; Porta-Benache, Jeremy; Blais, Jérôme

    2010-01-01

    The aim of this study was to assess the validity and accuracy of a commercial linear encoder (Musclelab, Ergotest, Norway) to estimate Bench press 1 repetition maximum (1RM) from the force - velocity relationship. Twenty seven physical education students and teachers (5 women and 22 men) with a heterogeneous history of strength training participated in this study. They performed a 1 RM test and a force - velocity test using a Bench press lifting task in a random order. Mean 1 RM was 61.8 ± 15...

  2. Perturbation Solutions for Random Linear Structural Systems subject to Random Excitation using Stochastic Differential Equations

    DEFF Research Database (Denmark)

    Köyluoglu, H.U.; Nielsen, Søren R.K.; Cakmak, A.S.

    1994-01-01

    perturbation method using stochastic differential equations. The joint statistical moments entering the perturbation solution are determined by considering an augmented dynamic system with state variables made up of the displacement and velocity vector and their first and second derivatives with respect......The paper deals with the first and second order statistical moments of the response of linear systems with random parameters subject to random excitation modelled as white-noise multiplied by an envelope function with random parameters. The method of analysis is basically a second order...... to the random parameters of the problem. Equations for partial derivatives are obtained from the partial differentiation of the equations of motion. The zero time-lag joint statistical moment equations for the augmented state vector are derived from the Itô differential formula. General formulation is given...

  3. High Velocity Spectroscopic Binary Orbits from Photoelectric Radial Velocities: BD+20 5152, a Possible Triple System

    Directory of Open Access Journals (Sweden)

    Sperauskas J.

    2010-12-01

    Full Text Available The spectroscopic orbit of a high proper motion star, BD+20 5152, is calculated from 34 CORAVEL-type radial velocity measurements. The star has a slightly eccentric orbit with a period of 5.70613 d, half-amplitude of 47.7 km/s and eccentricity of 0.049. The center-of-mass velocity of the system is -24.3 km/s. BD+20 5152 seems to be a triple system consisting of a G8 dwarf as a primary component and of two K6-M0 dwarfs as secondary and tertiary components. This model is based on the analysis of its UBVRI and JHK magnitudes. According to the SuperWASP photometry, spots on the surface of the primary are suspected. The excessive brightness in the Galex FUV and NUV magnitudes and a non-zero eccentricity suggest the age of this system to be less than 1 Gyr.

  4. How random is a random vector?

    Science.gov (United States)

    Eliazar, Iddo

    2015-12-01

    Over 80 years ago Samuel Wilks proposed that the "generalized variance" of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the "Wilks standard deviation" -the square root of the generalized variance-is indeed the standard deviation of a random vector. We further establish that the "uncorrelation index" -a derivative of the Wilks standard deviation-is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: "randomness measures" and "independence indices" of random vectors. In turn, these general notions give rise to "randomness diagrams"-tangible planar visualizations that answer the question: How random is a random vector? The notion of "independence indices" yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

  5. How random is a random vector?

    International Nuclear Information System (INIS)

    Eliazar, Iddo

    2015-01-01

    Over 80 years ago Samuel Wilks proposed that the “generalized variance” of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the “Wilks standard deviation” –the square root of the generalized variance–is indeed the standard deviation of a random vector. We further establish that the “uncorrelation index” –a derivative of the Wilks standard deviation–is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: “randomness measures” and “independence indices” of random vectors. In turn, these general notions give rise to “randomness diagrams”—tangible planar visualizations that answer the question: How random is a random vector? The notion of “independence indices” yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

  6. Radial Velocities of 41 Kepler Eclipsing Binaries

    Science.gov (United States)

    Matson, Rachel A.; Gies, Douglas R.; Guo, Zhao; Williams, Stephen J.

    2017-12-01

    Eclipsing binaries are vital for directly determining stellar parameters without reliance on models or scaling relations. Spectroscopically derived parameters of detached and semi-detached binaries allow us to determine component masses that can inform theories of stellar and binary evolution. Here we present moderate resolution ground-based spectra of stars in close binary systems with and without (detected) tertiary companions observed by NASA’s Kepler mission and analyzed for eclipse timing variations. We obtain radial velocities and spectroscopic orbits for five single-lined and 35 double-lined systems, and confirm one false positive eclipsing binary. For the double-lined spectroscopic binaries, we also determine individual component masses and examine the mass ratio {M}2/{M}1 distribution, which is dominated by binaries with like-mass pairs and semi-detached classical Algol systems that have undergone mass transfer. Finally, we constrain the mass of the tertiary component for five double-lined binaries with previously detected companions.

  7. Gas-rise velocities during kicks

    Energy Technology Data Exchange (ETDEWEB)

    White, D.B. (Sedco Forex (FR))

    1991-12-01

    This paper reports on experiments to examine gas migration rates in drilling muds that were performed in a 15-m-long, 200-mm-ID inclinable flow loop where air injection simulates gas entry during a kick. These tests were conducted using a xanthum gum (a common polymer used in drilling fluids) solution to simulate drilling muds as the liquid phase and air as the gas phase. This work represents a significant extension of existing correlations for gas/liquid flows in large pipe diameters with non- Newtonian fluids. Bubbles rise faster in drilling muds than in water despite the increased viscosity. This surprising result is caused by the change in the flow regime, with large slug-type bubbles forming at lower void fractions. The gas velocity is independent of void fraction, thus simplifying flow modeling. Results show that a gas influx will rise faster in a well than previously believed. This has major implications for kick simulation, with gas arriving at the surface earlier than would be expected and the gas outflow rate being higher than would have been predicted. A model of the two-phase gas flow in drilling mud, including the results of this work, has been incorporated into the joint Schlumberger Cambridge Research (SCR)/BP Intl. kick model.

  8. Coronary flow velocity reserve by echocardiography

    DEFF Research Database (Denmark)

    Olsen, Rasmus Huan; Pedersen, Lene Rørholm; Snoer, Martin

    2016-01-01

    BACKGROUND: Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography of the LAD is used to assess microvascular function but validation studies in clinical settings are lacking. We aimed to assess feasibility, reproducibility and agreement with myocardial flow...... performed within a week (1-week) and for all scans regardless of time gap (total) and to account for scar tissue for patients with and without previous myocardial infarction (MI). RESULTS: Eighty-six patients with median BMI 30.9 (IQR 29.4-32.9) kg × m(-2) and CFVR 2.29 (1.90-2.63) were included. CFVR...... was feasible in 83 (97 %) using a contrast agent in 14 %. For reproducibility overall (n = 21) limits of agreement (LOA) were (-0.75;0.71), within-subjects coefficient of variation (CV) 11 %, and reliability 0.84. For reproducibility within 1-week (n = 13) LOA were (-0.33;0.25), within-subjects CV 5...

  9. Spacecraft attitude and velocity control system

    Science.gov (United States)

    Paluszek, Michael A. (Inventor); Piper, Jr., George E. (Inventor)

    1992-01-01

    A spacecraft attitude and/or velocity control system includes a controller which responds to at least attitude errors to produce command signals representing a force vector F and a torque vector T, each having three orthogonal components, which represent the forces and torques which are to be generated by the thrusters. The thrusters may include magnetic torquer or reaction wheels. Six difference equations are generated, three having the form ##EQU1## where a.sub.j is the maximum torque which the j.sup.th thruster can produce, b.sub.j is the maximum force which the j.sup.th thruster can produce, and .alpha..sub.j is a variable representing the throttling factor of the j.sup.th thruster, which may range from zero to unity. The six equations are summed to produce a single scalar equation relating variables .alpha..sub.j to a performance index Z: ##EQU2## Those values of .alpha. which maximize the value of Z are determined by a method for solving linear equations, such as a linear programming method. The Simplex method may be used. The values of .alpha..sub.j are applied to control the corresponding thrusters.

  10. Angular velocity and centripetal acceleration relationship

    Science.gov (United States)

    Monteiro, Martín; Cabeza, Cecilia; Marti, Arturo C.; Vogt, Patrik; Kuhn, Jochen

    2014-05-01

    During the last few years, the growing boom of smartphones has given rise to a considerable number of applications exploiting the functionality of the sensors incorporated in these devices. A sector that has unexpectedly taken advantage of the power of these tools is physics teaching, as reflected in several recent papers. In effect, the use of smartphones has been proposed in several physics experiments spanning mechanics, electromagnetism, optics, oscillations, and waves, among other subjects. Although mechanical experiments have received considerable attention, most of them are based on the use of the accelerometer. An aspect that has received less attention is the use of rotation sensors or gyroscopes. An additional advance in the use of these devices is given by the possibility of obtaining data using the accelerometer and the gyroscope simultaneously. The aim of this paper is to consider the relation between the centripetal acceleration and the angular velocity. Instead of using a formal laboratory setup, in this experiment a smartphone is attached to the floor of a merry-go-round, found in many playgrounds. Several experiments were performed with the roundabout rotating in both directions and with the smart-phone at different distances from the center. The coherence of the measurements is shown.

  11. Standardization of the cumulative absolute velocity

    International Nuclear Information System (INIS)

    O'Hara, T.F.; Jacobson, J.P.

    1991-12-01

    EPRI NP-5930, ''A Criterion for Determining Exceedance of the Operating Basis Earthquake,'' was published in July 1988. As defined in that report, the Operating Basis Earthquake (OBE) is exceeded when both a response spectrum parameter and a second damage parameter, referred to as the Cumulative Absolute Velocity (CAV), are exceeded. In the review process of the above report, it was noted that the calculation of CAV could be confounded by time history records of long duration containing low (nondamaging) acceleration. Therefore, it is necessary to standardize the method of calculating CAV to account for record length. This standardized methodology allows consistent comparisons between future CAV calculations and the adjusted CAV threshold value based upon applying the standardized methodology to the data set presented in EPRI NP-5930. The recommended method to standardize the CAV calculation is to window its calculation on a second-by-second basis for a given time history. If the absolute acceleration exceeds 0.025g at any time during each one second interval, the earthquake records used in EPRI NP-5930 have been reanalyzed and the adjusted threshold of damage for CAV was found to be 0.16g-set

  12. Velocity-selective dark states in rubidium

    International Nuclear Information System (INIS)

    Esslinger, T.

    1995-06-01

    There are two recent developments exerting a strong influence on atomic physics: cooling of atomic gases with laser light, and optics with matter waves. The report addresses both fields. A mechanism for the cooling of atoms is examined, with the wave character of the atom playing an important part in the process. A novel atomic beam experiment has been worked out and is reported which represents application of this cooling method to an alkali atom for the first time. The basic principle of the cooling process is that atoms are optically pumped into quantum states by means of interaction with a standing laser wave, the quantum states having a sharply defined momentum, decoupled from the light field. These states are called dark states, as their dipole moment does not couple to the field of a resonant laser wave. In a one-dimensional standing laser wave with spatially varying polarization, the dark state is delocalised. This state is called velocity-selective dark state (VSDS). So far, such VSDS have only been observed in helium atoms. We succeded for the first time in detecting the population of VSDS with an experiment using alkali atoms. Atoms of a cold rubidium beam are optically pumped into VSDS by way of interaction with a one-dimensional standing laser wave. (orig./MM) [de

  13. Reliability of performance velocity for jump squats under feedback and nonfeedback conditions.

    Science.gov (United States)

    Randell, Aaron D; Cronin, John B; Keogh, Justin Wl; Gill, Nicholas D; Pedersen, Murray C

    2011-12-01

    Randell, AD, Cronin, JB, Keogh, JWL, Gill, ND, and Pedersen, MC. Reliability of performance velocity for jump squats under feedback and nonfeedback conditions. J Strength Cond Res 25(12): 3514-3518, 2011-Advancements in the monitoring of kinematic and kinetic variables during resistance training have resulted in the ability to continuously monitor performance and provide feedback during training. If equipment and software can provide reliable instantaneous feedback related to the variable of interest during training, it is thought that this may result in goal-oriented movement tasks that increase the likelihood of transference to on-field performance or at the very least improve the mechanical variable of interest. The purpose of this study was to determine the reliability of performance velocity for jump squats under feedback and nonfeedback conditions over 3 consecutive training sessions. Twenty subjects were randomly allocated to a feedback or nonfeedback group, and each group performed a total of 3 "jump squat" training sessions with the velocity of each repetition measured using a linear position transducer. There was less change in mean velocities between sessions 1-2 and sessions 2-3 (0.07 and 0.02 vs. 0.13 and -0.04 m·s), less random variation (TE = 0.06 and 0.06 vs. 0.10 and 0.07 m·s) and greater consistency (intraclass correlation coefficient = 0.83 and 0.87 vs. 0.53 and 0.74) between sessions for the feedback condition as compared to the nonfeedback condition. It was concluded that there is approximately a 50-50 probability that the provision of feedback was beneficial to the performance in the squat jump over multiple sessions. It is suggested that this has the potential for increasing transference to on-field performance or at the very least improving the mechanical variable of interest.

  14. Convergence of a random walk method for the Burgers equation

    International Nuclear Information System (INIS)

    Roberts, S.

    1985-10-01

    In this paper we consider a random walk algorithm for the solution of Burgers' equation. The algorithm uses the method of fractional steps. The non-linear advection term of the equation is solved by advecting ''fluid'' particles in a velocity field induced by the particles. The diffusion term of the equation is approximated by adding an appropriate random perturbation to the positions of the particles. Though the algorithm is inefficient as a method for solving Burgers' equation, it does model a similar method, the random vortex method, which has been used extensively to solve the incompressible Navier-Stokes equations. The purpose of this paper is to demonstrate the strong convergence of our random walk method and so provide a model for the proof of convergence for more complex random walk algorithms; for instance, the random vortex method without boundaries

  15. Ballistic transport through graphene nanostructures of velocity and potential barriers

    International Nuclear Information System (INIS)

    Krstajic, P M; Vasilopoulos, P

    2011-01-01

    We investigate the electronic properties of graphene nanostructures when the Fermi velocity and the electrostatic potential vary in space. First, we consider the transmission T and conductance G through single and double barriers. We show that G for velocity barriers differs markedly from that for potential barriers for energies below the height of the latter and it exhibits periodic oscillations as a function of the energy for strong velocity modulation. Special attention is given to superlattices (SLs). It is shown that an applied bias can efficiently widen or shrink the allowed minibands of velocity-modulated SLs. The spectrum in the Kronig-Penney limit is periodic in the strength of the barriers. Collimation of an electron beam incident on an SL with velocity and potential barriers is present but it disappears when the potential barriers are absent. The number of additional Dirac points may change considerably if barriers and wells have sufficiently different Fermi velocities.

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

    DEFF Research Database (Denmark)

    Shokouhi, Parisa; Zoëga, Andreas; Wiggenhauser, Herbert

    2012-01-01

    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...... 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...

  17. A new car-following model considering velocity anticipation

    International Nuclear Information System (INIS)

    Jun-Fang, Tian; Bin, Jia; Xin-Gang, Li; Zi-You, Gao

    2010-01-01

    The full velocity difference model proposed by Jiang et al. [2001 Phys. Rev. E 64 017101] has been improved by introducing velocity anticipation. Velocity anticipation means the follower estimates the future velocity of the leader. The stability condition of the new model is obtained by using the linear stability theory. Theoretical results show that the stability region increases when we increase the anticipation time interval. The mKdV equation is derived to describe the kink–antikink soliton wave and obtain the coexisting stability line. The delay time of car motion and kinematic wave speed at jam density are obtained in this model. Numerical simulations exhibit that when we increase the anticipation time interval enough, the new model could avoid accidents under urgent braking cases. Also, the traffic jam could be suppressed by considering the anticipation velocity. All results demonstrate that this model is an improvement on the full velocity difference model. (general)

  18. Analyses of subchannel velocity distribution for HANARO fuel assembly

    International Nuclear Information System (INIS)

    Chae, Hee Taek; Han, Gee Yang; Park, Cheol; Lim, In Cheol

    1998-10-01

    MATRA-h which is a subchannel analysis computer code is used to evaluate the thermal margin of HANARO core. To estimate core thermal margin, accurate prediction of subchannel velocity is very important. The average subchannel velocities of 18 element fuel assembly were obtained from the results of velocity measurement test. To validate the adequacy of the hydraulic model code predictions were compared with the experimental results for the subchannel velocity distribution in 18 element fuel channel. The calculated subchannel velocity distributions in the central channels were larger than those of experiment. On the other hand the subchannel velocities in the outer channels were smaller. It is speculated that the prediction like as above would make CHF value lower because CHF phenomena had been occurred in the outer fuel element in the bundle CHF test of AECL. The prediction for axial pressure distribution coincided with the experimental results well. (author). 9 refs., 9 tabs., 14 figs

  19. A comparative study of calculated and measured particle velocities

    International Nuclear Information System (INIS)

    Tariq, S.M.

    2005-01-01

    After an explosive is detonated in a blast hole, seismic waves are generated in the ground surrounding the blast hole. These waves cause the particles of rock to oscillate about its position. As the wave attenuate, the particles come back to their original position. The rapidity with which the particles move is called the particle velocity. The peak or maximum velocity is the value which is of prime concern. This value of peak particle velocity can be estimated by the equations determined by the United States Bureau of Mines and by the DUPONT. A research program was conducted by the author at the 'Beck Materials Quarry' situated near Rolla, Missouri, USA. The purpose was to draw a comparison between the predicted and measured particle velocities. It was generally found that the predicted peak particle velocities were quite high as compared to the velocities measured by the Seismographs. (author)

  20. Different velocities in wave trains: early definitions and interpretations

    International Nuclear Information System (INIS)

    Lombardi, Anna M

    2002-01-01

    Recent experiments force us to re-examine the physical significance of the different velocities which one can introduce to describe the propagation of a wave train. In this paper we collect together the early definitions of these velocities, and their physical interpretations, dating back to the end of the 19th and to the first decades of the 20th century. Our purpose is to examine the scientific contexts in which some relevant definitions of velocities emerged, with particular attention paid to the early definitions of the group velocity. We recall some debates in which the group velocity had a dominant role, in order to follow the evolution of the physical meanings that have been ascribed to it. Finally, we focus our attention on the connection between the introduction of the group velocity and the problem of white light

  1. Additional radial velocities of supergiants in the Small Magellanic Cloud

    International Nuclear Information System (INIS)

    Thackeray, A.D.

    1978-01-01

    Additional radial velocities of 28 SMC supergiants determined in the years 1959-69 at the Radcliffe Observatory are presented. These and other measures from ESO and elsewhere are intercompared. The mean Radcliffe velocities have an internal standard error of +- 4.7 km/s and a systematic error exceeding 4 km/s is regarded as unlikely. Eight stars in the SMC core have a corrected velocity dispersion of only 6.9 km/s, similar to Feast's values for H II regions in the core. But the core H II regions have a velocity differential of -20 km/s relative to these stars. The velocity dispersion for stars in other parts of the Cloud is of the order 15 km/s as previously found. Two possibly variable-velocity stars are discussed, without reaching a satisfactory conclusion. (author)

  2. Galilean invariance and homogeneous anisotropic randomly stirred flows

    International Nuclear Information System (INIS)

    Berera, Arjun; Hochberg, David

    2005-01-01

    The Ward-Takahashi identities for incompressible flow implied by Galilean invariance are derived for the randomly forced Navier-Stokes equation, in which both the mean and fluctuating velocity components are explicitly present. The consequences of the Galilean invariance for the vertex renormalization are drawn from this identity

  3. Temperature dependence of sound velocity in yttrium ferrite

    International Nuclear Information System (INIS)

    L'vov, V.A.

    1979-01-01

    The effect of the phonon-magnon and phonon-phonon interoctions on the temperature dependence of the longitudinal sound velocity in yttrium ferrite is considered. It has been shown that at low temperatures four-particle phonon-magnon processes produce the basic contribution to renormalization of the sound velocity. At higher temperatures the temperature dependence of the sound velocity is mainly defined by phonon-phonon processes

  4. A New Filtering Algorithm Utilizing Radial Velocity Measurement

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-feng; DU Zi-cheng; PAN Quan

    2005-01-01

    Pulse Doppler radar measurements consist of range, azimuth, elevation and radial velocity. Most of the radar tracking algorithms in engineering only utilize position measurement. The extended Kalman filter with radial velocity measureneut is presented, then a new filtering algorithm utilizing radial velocity measurement is proposed to improve tracking results and the theoretical analysis is also given. Simulation results of the new algorithm, converted measurement Kalman filter, extended Kalman filter are compared. The effectiveness of the new algorithm is verified by simulation results.

  5. The effects of varying resistance-training loads on intermediate- and high-velocity-specific adaptations.

    Science.gov (United States)

    Jones, K; Bishop, P; Hunter, G; Fleisig, G

    2001-08-01

    The purpose of this study was to compare changes in velocity-specific adaptations in moderately resistance-trained athletes who trained with either low or high resistances. The study used tests of sport-specific skills across an intermediate- to high-velocity spectrum. Thirty NCAA Division I baseball players were randomly assigned to either a low-resistance (40-60% 1 repetition maximum [1RM]) training group or a high-resistance (70-90% 1RM) training group. Both of the training groups intended to maximallv accelerate each repetition during the concentric phase (IMCA). The 10 weeks of training consisted of 4 training sessions a week using basic core exercises. Peak force, velocity, and power were evaluated during set angle and depth jumps as well as weighted jumps using 30 and 50% 1RM. Squat 1RMs were also tested. Although no interactions for any of the jump tests were found, trends supported the hypothesis of velocity-specific training. Percentage gains suggest that the combined use of heavier training loads (70-90% 1RM) and IMCA tend to increase peak force in the lower-body leg and hip extensors. Trends also show that the combined use of lighter training loads (40-60% 1RM) and IMCA tend to increase peak power and peak velocity in the lower-body leg and hip extensors. The high-resistance group improved squats more than the low-resistance group (p training loads and IMCA to increase 1RM strength in the lower bodies of resistance-trained athletes.

  6. Predicting the Maximum Dynamic Strength in Bench Press: The High Precision of the Bar Velocity Approach.

    Science.gov (United States)

    Loturco, Irineu; Kobal, Ronaldo; Moraes, José E; Kitamura, Katia; Cal Abad, César C; Pereira, Lucas A; Nakamura, Fábio Y

    2017-04-01

    Loturco, I, Kobal, R, Moraes, JE, Kitamura, K, Cal Abad, CC, Pereira, LA, and Nakamura, FY. Predicting the maximum dynamic strength in bench press: the high precision of the bar velocity approach. J Strength Cond Res 31(4): 1127-1131, 2017-The aim of this study was to determine the force-velocity relationship and test the possibility of determining the 1 repetition maximum (1RM) in "free weight" and Smith machine bench presses. Thirty-six male top-level athletes from 3 different sports were submitted to a standardized 1RM bench press assessment (free weight or Smith machine, in randomized order), following standard procedures encompassing lifts performed at 40-100% of 1RM. The mean propulsive velocity (MPV) was measured in all attempts. A linear regression was performed to establish the relationships between bar velocities and 1RM percentages. The actual and predicted 1RM for each exercise were compared using a paired t-test. Although the Smith machine 1RM was higher (10% difference) than the free weight 1RM, in both cases the actual and predicted values did not differ. In addition, the linear relationship between MPV and percentage of 1RM (coefficient of determination ≥95%) allow determination of training intensity based on the bar velocity. The linear relationships between the MPVs and the relative percentages of 1RM throughout the entire range of loads enable coaches to use the MPV to accurately monitor their athletes on a daily basis and accurately determine their actual 1RM without the need to perform standard maximum dynamic strength assessments.

  7. Velocity-specific strength recovery after a second bout of eccentric exercise.

    Science.gov (United States)

    Barss, Trevor S; Magnus, Charlene R A; Clarke, Nick; Lanovaz, Joel L; Chilibeck, Philip D; Kontulainen, Saija A; Arnold, Bart E; Farthing, Jonathan P

    2014-02-01

    A bout of eccentric exercise (ECC) has the protective effect of reducing muscle damage during a subsequent bout of ECC known as the "repeated bout effect" (RBE). The purpose of this study was to determine if the RBE is greater when both bouts of ECC are performed using the same vs. different velocity of contraction. Thirty-one right-handed participants were randomly assigned to perform an initial bout of either fast (3.14 rad·s [180°·s]) or slow (0.52 rad·s [30°·s]) maximal isokinetic ECCs of the elbow flexors. Three weeks later, the participants completed another bout of ECC at the same velocity (n = 16), or at a different velocity (n = 15). Indirect muscle damage markers were measured before, immediately after, and at 24, 48, and 72 hours postexercise. Measures included maximal voluntary isometric contraction (MVC) strength (dynamometer), muscle thickness (MT; ultrasound), delayed onset muscle soreness (DOMS; visual analog scale), biceps and triceps muscle activation amplitude (electromyography), voluntary activation (interpolated twitch), and twitch torque. After the repeated bout, MVC strength recovered faster compared with the same time points after the initial bout for only the same velocity group (p = 0.017), with no differences for all the other variables. Irrespective of velocity, MT and DOMS were reduced after the repeated bout compared with that of the initial bout at 24, 48, and 72 hours with a corresponding increase in TT at 72 hours (p effects contribute to the RBE. The current findings support the idea of multiple mechanisms contributing to the RBE.

  8. Measuring the Bed Load velocity in Laboratory flumes using ADCP and Digital Cameras

    Science.gov (United States)

    Conevski, Slaven; Guerrero, Massimo; Rennie, Colin; Bombardier, Josselin

    2017-04-01

    Measuring the transport rate and apparent velocity of the bedload is notoriously hard and there is not a certain technique that would obtain continues data. There are many empirical models, based on the estimation of the shear stress, but only few involve direct measurement of the bed load velocity. The bottom tracking (BT) mode of an acoustic Doppler current profiler (ADCP) has been used many times to estimate the apparent velocity of the bed load. Herein is the basic idea, to exploit the bias of the BT signal towards the bed load movement and to calibrate this signal with traditional measuring techniques. These measurements are quite scarce and seldom reliable since there are not taken in controlled conditions. So far, no clear confirmation has been conducted in laboratory-controlled conditions that would attest the assumptions made in the estimation of the apparent bed load velocity, nor in the calibration of the empirical equations. Therefore, this study explores several experiments under stationary conditions, where the signal of the ADCP BT mode is recorded and compared to the bed load motion recorded by digital camera videography. The experiments have been performed in the hydraulic laboratories of Ottawa and Bologna, using two different ADCPs and two different high resolution cameras. In total, more then 30 experiments were performed for different sediment mixtures and different hydraulic conditions. In general, a good match is documented between the apparent bed load velocity measured by the ADCP and the videography. The slight deviation in single experiments can be explained by gravel particles inhomogeneity, difficult in reproducing the same hydro-sedimentological conditions and the randomness of the backscattering strength.

  9. Velocity overshoot decay mechanisms in compound semiconductor field-effect transistors with a submicron characteristic length

    International Nuclear Information System (INIS)

    Jyegal, Jang

    2015-01-01

    Velocity overshoot is a critically important nonstationary effect utilized for the enhanced performance of submicron field-effect devices fabricated with high-electron-mobility compound semiconductors. However, the physical mechanisms of velocity overshoot decay dynamics in the devices are not known in detail. Therefore, a numerical analysis is conducted typically for a submicron GaAs metal-semiconductor field-effect transistor in order to elucidate the physical mechanisms. It is found that there exist three different mechanisms, depending on device bias conditions. Specifically, at large drain biases corresponding to the saturation drain current (dc) region, the velocity overshoot suddenly begins to drop very sensitively due to the onset of a rapid decrease of the momentum relaxation time, not the mobility, arising from the effect of velocity-randomizing intervalley scattering. It then continues to drop rapidly and decays completely by severe mobility reduction due to intervalley scattering. On the other hand, at small drain biases corresponding to the linear dc region, the velocity overshoot suddenly begins to drop very sensitively due to the onset of a rapid increase of thermal energy diffusion by electrons in the channel of the gate. It then continues to drop rapidly for a certain channel distance due to the increasing thermal energy diffusion effect, and later completely decays by a sharply decreasing electric field. Moreover, at drain biases close to a dc saturation voltage, the mechanism is a mixture of the above two bias conditions. It is suggested that a large secondary-valley energy separation is essential to increase the performance of submicron devices

  10. Unipedal balance in healthy adults: effect of visual environments yielding decreased lateral velocity feedback.

    Science.gov (United States)

    Deyer, T W; Ashton-Miller, J A

    1999-09-01

    To test the (null) hypotheses that the reliability of unipedal balance is unaffected by the attenuation of visual velocity feedback and that, relative to baseline performance, deterioration of balance success rates from attenuated visual velocity feedback will not differ between groups of young men and older women, and the presence (or absence) of a vertical foreground object will not affect balance success rates. Single blind, single case study. University research laboratory. Two volunteer samples: 26 healthy young men (mean age, 20.0yrs; SD, 1.6); 23 healthy older women (mean age, 64.9 yrs; SD, 7.8). Normalized success rates in unipedal balance task. Subjects were asked to transfer to and maintain unipedal stance for 5 seconds in a task near the limit of their balance capabilities. Subjects completed 64 trials: 54 trials of three experimental visual scenes in blocked randomized sequences of 18 trials and 10 trials in a normal visual environment. The experimental scenes included two that provided strong velocity/weak position feedback, one of which had a vertical foreground object (SVWP+) and one without (SVWP-), and one scene providing weak velocity/strong position (WVSP) feedback. Subjects' success rates in the experimental environments were normalized by the success rate in the normal environment in order to allow comparisons between subjects using a mixed model repeated measures analysis of variance. The normalized success rate was significantly greater in SVWP+ than in WVSP (p = .0001) and SVWP- (p = .013). Visual feedback significantly affected the normalized unipedal balance success rates (p = .001); neither the group effect nor the group X visual environment interaction was significant (p = .9362 and p = .5634, respectively). Normalized success rates did not differ significantly between the young men and older women in any visual environment. Near the limit of the young men's or older women's balance capability, the reliability of transfer to unipedal

  11. RADIAL VELOCITY MONITORING OF KEPLER HEARTBEAT STARS

    Energy Technology Data Exchange (ETDEWEB)

    Shporer, Avi [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Fuller, Jim [TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, Caltech, Pasadena, CA 91125 (United States); Isaacson, Howard [Department of Astronomy, University of California, Berkeley CA 94720 (United States); Hambleton, Kelly; Prša, Andrej [Department of Astrophysics and Planetary Science, Villanova University, 800 East Lancaster Avenue, Villanova, PA 19085 (United States); Thompson, Susan E. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Kurtz, Donald W. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE (United Kingdom); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); O’Leary, Ryan M. [JILA, University of Colorado and NIST, 440 UCB, Boulder, 80309-0440 (United States)

    2016-09-20

    Heartbeat stars (HB stars) are a class of eccentric binary stars with close periastron passages. The characteristic photometric HB signal evident in their light curves is produced by a combination of tidal distortion, heating, and Doppler boosting near orbital periastron. Many HB stars continue to oscillate after periastron and along the entire orbit, indicative of the tidal excitation of oscillation modes within one or both stars. These systems are among the most eccentric binaries known, and they constitute astrophysical laboratories for the study of tidal effects. We have undertaken a radial velocity (RV) monitoring campaign of Kepler HB stars in order to measure their orbits. We present our first results here, including a sample of 22 Kepler HB systems, where for 19 of them we obtained the Keplerian orbit and for 3 other systems we did not detect a statistically significant RV variability. Results presented here are based on 218 spectra obtained with the Keck/HIRES spectrograph during the 2015 Kepler observing season, and they have allowed us to obtain the largest sample of HB stars with orbits measured using a single instrument, which roughly doubles the number of HB stars with an RV measured orbit. The 19 systems measured here have orbital periods from 7 to 90 days and eccentricities from 0.2 to 0.9. We show that HB stars draw the upper envelope of the eccentricity–period distribution. Therefore, HB stars likely represent a population of stars currently undergoing high eccentricity migration via tidal orbital circularization, and they will allow for new tests of high eccentricity migration theories.

  12. Nonlinear peculiar-velocity analysis and PCA

    Energy Technology Data Exchange (ETDEWEB)

    Dekel, A. [and others

    2001-02-20

    We allow for nonlinear effects in the likelihood analysis of peculiar velocities, and obtain {approximately}35%-lower values for the cosmological density parameter and for the amplitude of mass-density fluctuations. The power spectrum in the linear regime is assumed to be of the flat {Lambda}CDM model (h = 0:65, n = 1) with only {Omega}{sub m} free. Since the likelihood is driven by the nonlinear regime, we break the power spectrum at k{sub b} {approximately} 0.2 (h{sup {minus}1} Mpc){sup {minus}1} and fit a two-parameter power-law at k > k{sub b} . This allows for an unbiased fit in the linear regime. Tests using improved mock catalogs demonstrate a reduced bias and a better fit. We find for the Mark III and SFI data {Omega}{sub m} = 0.35 {+-} 0.09 with {sigma}{sub 8}{Omega}P{sub m}{sup 0.6} = 0.55 {+-} 0.10 (90% errors). When allowing deviations from {Lambda}CDM, we find an indication for a wiggle in the power spectrum in the form of an excess near k {approximately} 0.05 and a deficiency at k {approximately} 0.1 (h{sup {minus}1} Mpc){sup {minus}1}--a cold flow which may be related to a feature indicated from redshift surveys and the second peak in the CMB anisotropy. A {chi}{sup 2} test applied to principal modes demonstrates that the nonlinear procedure improves the goodness of fit. The Principal Component Analysis (PCA) helps identifying spatial features of the data and fine-tuning the theoretical and error models. We address the potential for optimal data compression using PCA.

  13. RADIAL VELOCITY MONITORING OF KEPLER HEARTBEAT STARS

    International Nuclear Information System (INIS)

    Shporer, Avi; Fuller, Jim; Isaacson, Howard; Hambleton, Kelly; Prša, Andrej; Thompson, Susan E.; Kurtz, Donald W.; Howard, Andrew W.; O’Leary, Ryan M.

    2016-01-01

    Heartbeat stars (HB stars) are a class of eccentric binary stars with close periastron passages. The characteristic photometric HB signal evident in their light curves is produced by a combination of tidal distortion, heating, and Doppler boosting near orbital periastron. Many HB stars continue to oscillate after periastron and along the entire orbit, indicative of the tidal excitation of oscillation modes within one or both stars. These systems are among the most eccentric binaries known, and they constitute astrophysical laboratories for the study of tidal effects. We have undertaken a radial velocity (RV) monitoring campaign of Kepler HB stars in order to measure their orbits. We present our first results here, including a sample of 22 Kepler HB systems, where for 19 of them we obtained the Keplerian orbit and for 3 other systems we did not detect a statistically significant RV variability. Results presented here are based on 218 spectra obtained with the Keck/HIRES spectrograph during the 2015 Kepler observing season, and they have allowed us to obtain the largest sample of HB stars with orbits measured using a single instrument, which roughly doubles the number of HB stars with an RV measured orbit. The 19 systems measured here have orbital periods from 7 to 90 days and eccentricities from 0.2 to 0.9. We show that HB stars draw the upper envelope of the eccentricity–period distribution. Therefore, HB stars likely represent a population of stars currently undergoing high eccentricity migration via tidal orbital circularization, and they will allow for new tests of high eccentricity migration theories.

  14. Daily rhythm of cerebral blood flow velocity

    Directory of Open Access Journals (Sweden)

    Spielman Arthur J

    2005-03-01

    Full Text Available Abstract Background CBFV (cerebral blood flow velocity is lower in the morning than in the afternoon and evening. Two hypotheses have been proposed to explain the time of day changes in CBFV: 1 CBFV changes are due to sleep-associated processes or 2 time of day changes in CBFV are due to an endogenous circadian rhythm independent of sleep. The aim of this study was to examine CBFV over 30 hours of sustained wakefulness to determine whether CBFV exhibits fluctuations associated with time of day. Methods Eleven subjects underwent a modified constant routine protocol. CBFV from the middle cerebral artery was monitored by chronic recording of Transcranial Doppler (TCD ultrasonography. Other variables included core body temperature (CBT, end-tidal carbon dioxide (EtCO2, blood pressure, and heart rate. Salivary dim light melatonin onset (DLMO served as a measure of endogenous circadian phase position. Results A non-linear multiple regression, cosine fit analysis revealed that both the CBT and CBFV rhythm fit a 24 hour rhythm (R2 = 0.62 and R2 = 0.68, respectively. Circadian phase position of CBT occurred at 6:05 am while CBFV occurred at 12:02 pm, revealing a six hour, or 90 degree difference between these two rhythms (t = 4.9, df = 10, p Conclusion In conclusion, time of day variations in CBFV have an approximately 24 hour rhythm under constant conditions, suggesting regulation by a circadian oscillator. The 90 degree-phase angle difference between the CBT and CBFV rhythms may help explain previous findings of lower CBFV values in the morning. The phase difference occurs at a time period during which cognitive performance decrements have been observed and when both cardiovascular and cerebrovascular events occur more frequently. The mechanisms underlying this phase angle difference require further exploration.

  15. Background velocity inversion by phase along reflection wave paths

    KAUST Repository

    Yu, Han; Guo, Bowen; Schuster, Gerard T.

    2014-01-01

    A background velocity model containing the correct lowwavenumber information is desired for both the quality of the migration image and the success of waveform inversion. We propose to invert for the low-wavenumber part of the velocity model by minimizing the phase difference between predicted and observed reflections. The velocity update is exclusively along the reflection wavepaths and, unlike conventional FWI, not along the reflection ellipses. This allows for reconstructing the smoothly varying parts of the background velocity model. Tests with synthetic data show both the benefits and limitations of this method.

  16. Paintball velocity as a function of distance traveled

    Directory of Open Access Journals (Sweden)

    Pat Chiarawongse

    2008-06-01

    Full Text Available The relationship between the distance a paintball travels through air and its velocity is investigated by firing a paintball into a ballistic pendulum from a range of distances. The motion of the pendulum was filmed and analyzed by using video analysis software. The velocity of the paintball on impact was calculated from the maximum horizontal displacement of the pendulum. It is shown that the velocity of a paintball decreases exponentially with distance traveled, as expected. The average muzzle velocity of the paint balls is found with an estimate of the drag coefficient.

  17. Paintball velocity as a function of distance traveled

    Directory of Open Access Journals (Sweden)

    Pat Chiarawongse

    2008-06-01

    Full Text Available The relationship between the distance a paintball travels through air and its velocity is investigated by firing a paintball into a ballistic pendulum from a range of distances. The motion of the pendulum was filmed and analyzed by using video analysis software. The velocity of the paintball on impact was calculated from the maximum horizontal displacement of the pendulum. It is shown that the velocity of a paintball decreases exponentially with distance traveled, as expected. The average muzzle velocity of the paint balls is found with an estimate of the drag coefficient

  18. 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...... examines the use of particle velocity as the input of PNAH. Because the particle velocity decays faster toward the edges of the measurement aperture than the pressure does and because the wave number ratio that enters into the inverse propagator from pressure to velocity amplifies high spatial frequencies...

  19. Variation of the solar wind velocity following solar flares

    International Nuclear Information System (INIS)

    Huang, Y.; Lee, Y.

    1975-01-01

    By use of the superposed epoch method, changes in the solar wind velocity following solar flares have been investigated by using the solar wind velocity data obtained by Pioneer 6 and 7 and Vela 3, 4, and 5 satellites. A significant increase of the solar wind velocity has been found on the second day following importance 3 solar flares and on the third day following importance 2 solar flares. No significant increase of the solar wind velocity has been found for limb flares. (auth)

  20. Background velocity inversion by phase along reflection wave paths

    KAUST Repository

    Yu, Han

    2014-08-05

    A background velocity model containing the correct lowwavenumber information is desired for both the quality of the migration image and the success of waveform inversion. We propose to invert for the low-wavenumber part of the velocity model by minimizing the phase difference between predicted and observed reflections. The velocity update is exclusively along the reflection wavepaths and, unlike conventional FWI, not along the reflection ellipses. This allows for reconstructing the smoothly varying parts of the background velocity model. Tests with synthetic data show both the benefits and limitations of this method.

  1. Tables of the velocity of sound in sea water

    CERN Document Server

    Bark, L S; Meister, N A

    1964-01-01

    Tables of the Velocity of Sound in Sea Water contains tables of the velocity of sound in sea water computed on a ""Strela-3"" high-speed electronic computer and a T-5 tabulator at the Computational Center of the Academy of Sciences. Knowledge of the precise velocity of sound in sea water is of great importance when investigating sound propagations in the ocean and when solving practical problems involving the use of hydro-acoustic devices. This book demonstrates the computations made for the velocity of sound in sea water, which can be found in two ways: by direct measurement with the aid of s

  2. Parameters determining maximum wind velocity in a tropical cyclone

    International Nuclear Information System (INIS)

    Choudhury, A.M.

    1984-09-01

    The spiral structure of a tropical cyclone was earlier explained by a tangential velocity distribution which varies inversely as the distance from the cyclone centre outside the circle of maximum wind speed. The case has been extended in the present paper by adding a radial velocity. It has been found that a suitable combination of radial and tangential velocities can account for the spiral structure of a cyclone. This enables parametrization of the cyclone. Finally a formula has been derived relating maximum velocity in a tropical cyclone with angular momentum, radius of maximum wind speed and the spiral angle. The shapes of the spirals have been computed for various spiral angles. (author)

  3. Velocity measurement of model vertical axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.A.; McWilliam, M. [Waterloo Univ., ON (Canada). Dept. of Mechanical Engineering

    2006-07-01

    An increasingly popular solution to future energy demand is wind energy. Wind turbine designs can be grouped according to their axis of rotation, either horizontal or vertical. Horizontal axis wind turbines have higher power output in a good wind regime than vertical axis turbines and are used in most commercial class designs. Vertical axis Savonius-based wind turbine designs are still widely used in some applications because of their simplistic design and low wind speed performance. There are many design variables that must be considered in order to optimize the power output in a given wind regime in a typical wind turbine design. Using particle image velocimetry, a study of the air flow around five different model vertical axis wind turbines was conducted in a closed loop wind tunnel. A standard Savonius design with two semi-circular blades overlapping, and two variations of this design, a deep blade and a shallow blade design were among the turbine models included in this study. It also evaluated alternate designs that attempt to increase the performance of the standard design by allowing compound blade curvature. Measurements were collected at a constant phase angle and also at random rotor orientations. It was found that evaluation of the flow patterns and measured velocities revealed consistent and stable flow patterns at any given phase angle. Large scale flow structures are evident in all designs such as vortices shed from blade surfaces. An important performance parameter was considered to be the ability of the flow to remain attached to the forward blade and redirect and reorient the flow to the following blade. 6 refs., 18 figs.

  4. Orographic precipitation and vertical velocity characteristics from drop size and fall velocity spectra observed by disdrometers

    Science.gov (United States)

    Lee, Dong-In; Kim, Dong-Kyun; Kim, Ji-Hyeon; Kang, Yunhee; Kim, Hyeonjoon

    2017-04-01

    During a summer monsoon season each year, severe weather phenomena caused by front, mesoscale convective systems, or typhoons often occur in the southern Korean Peninsula where is mostly comprised of complex high mountains. These areas play an important role in controlling formation, amount, and distribution of rainfall. As precipitation systems move over the mountains, they can develop rapidly and produce localized heavy rainfall. Thus observational analysis in the mountainous areas is required for studying terrain effects on the rapid rainfall development and its microphysics. We performed intensive field observations using two s-band operational weather radars around Mt. Jiri (1950 m ASL) during summertime on June and July in 2015-2016. Observation data of DSD (Drop Size Distribution) from Parsivel disdrometer and (w component) vertical velocity data from ultrasonic anemometers were analyzed for Typhoon Chanhom on 12 July 2015 and the heavy rain event on 1 July 2016. During the heavy rain event, a dual-Doppler radar analysis using Jindo radar and Gunsan radar was also conducted to examine 3-D wind fields and vertical structure of reflectivity in these areas. For examining up-/downdrafts in the windward or leeward side of Mt. Jiri, we developed a new scheme technique to estimate vertical velocities (w) from drop size and fall velocity spectra of Parsivel disdrometers at different stations. Their comparison with the w values observed by the 3D anemometer showed quite good agreement each other. The Z histogram with regard to the estimated w was similar to that with regard to R, indicating that Parsivel-estimated w is quite reasonable for classifying strong and weak rain, corresponding to updraft and downdraft, respectively. Mostly, positive w values (upward) were estimated in heavy rainfall at the windward side (D1 and D2). Negative w values (downward) were dominant even during large rainfall at the leeward side (D4). For D1 and D2, the upward w percentages were

  5. Evaluation of force-velocity and power-velocity relationship of arm muscles.

    Science.gov (United States)

    Sreckovic, Sreten; Cuk, Ivan; Djuric, Sasa; Nedeljkovic, Aleksandar; Mirkov, Dragan; Jaric, Slobodan

    2015-08-01

    A number of recent studies have revealed an approximately linear force-velocity (F-V) and, consequently, a parabolic power-velocity (P-V) relationship of multi-joint tasks. However, the measurement characteristics of their parameters have been neglected, particularly those regarding arm muscles, which could be a problem for using the linear F-V model in both research and routine testing. Therefore, the aims of the present study were to evaluate the strength, shape, reliability, and concurrent validity of the F-V relationship of arm muscles. Twelve healthy participants performed maximum bench press throws against loads ranging from 20 to 70 % of their maximum strength, and linear regression model was applied on the obtained range of F and V data. One-repetition maximum bench press and medicine ball throw tests were also conducted. The observed individual F-V relationships were exceptionally strong (r = 0.96-0.99; all P stronger relationships. The reliability of parameters obtained from the linear F-V regressions proved to be mainly high (ICC > 0.80), while their concurrent validity regarding directly measured F, P, and V ranged from high (for maximum F) to medium-to-low (for maximum P and V). The findings add to the evidence that the linear F-V and, consequently, parabolic P-V models could be used to study the mechanical properties of muscular systems, as well as to design a relatively simple, reliable, and ecologically valid routine test of the muscle ability of force, power, and velocity production.

  6. Analog model for quantum gravity effects: phonons in random fluids.

    Science.gov (United States)

    Krein, G; Menezes, G; Svaiter, N F

    2010-09-24

    We describe an analog model for quantum gravity effects in condensed matter physics. The situation discussed is that of phonons propagating in a fluid with a random velocity wave equation. We consider that there are random fluctuations in the reciprocal of the bulk modulus of the system and study free phonons in the presence of Gaussian colored noise with zero mean. We show that, in this model, after performing the random averages over the noise function a free conventional scalar quantum field theory describing free phonons becomes a self-interacting model.

  7. Global Plate Velocities from the Global Positioning System

    Science.gov (United States)

    Larson, Kristine M.; Freymueller, Jeffrey T.; Philipsen, Steven

    1997-01-01

    We have analyzed 204 days of Global Positioning System (GPS) data from the global GPS network spanning January 1991 through March 1996. On the basis of these GPS coordinate solutions, we have estimated velocities for 38 sites, mostly located on the interiors of the Africa, Antarctica, Australia, Eurasia, Nazca, North America, Pacific, and South America plates. The uncertainties of the horizontal velocity components range from 1.2 to 5.0 mm/yr. With the exception of sites on the Pacific and Nazca plates, the GPS velocities agree with absolute plate model predictions within 95% confidence. For most of the sites in North America, Antarctica, and Eurasia, the agreement is better than 2 mm/yr. We find no persuasive evidence for significant vertical motions (less than 3 standard deviations), except at four sites. Three of these four were sites constrained to geodetic reference frame velocities. The GPS velocities were then used to estimate angular velocities for eight tectonic plates. Absolute angular velocities derived from the GPS data agree with the no net rotation (NNR) NUVEL-1A model within 95% confidence except for the Pacific plate. Our pole of rotation for the Pacific plate lies 11.5 deg west of the NNR NUVEL-1A pole, with an angular speed 10% faster. Our relative angular velocities agree with NUVEL-1A except for some involving the Pacific plate. While our Pacific-North America angular velocity differs significantly from NUVEL-1A, our model and NUVEL-1A predict very small differences in relative motion along the Pacific-North America plate boundary itself. Our Pacific-Australia and Pacific- Eurasia angular velocities are significantly faster than NUVEL-1A, predicting more rapid convergence at these two plate boundaries. Along the East Pacific Pise, our Pacific-Nazca angular velocity agrees in both rate and azimuth with NUVFL-1A.

  8. Shear wave crustal velocity model of the Western Bohemian Massif from Love wave phase velocity dispersion

    Czech Academy of Sciences Publication Activity Database

    Kolínský, Petr; Málek, Jiří; Brokešová, J.

    2011-01-01

    Roč. 15, č. 1 (2011), s. 81-104 ISSN 1383-4649 R&D Projects: GA AV ČR IAA300460602; GA AV ČR IAA300460705; GA ČR(CZ) GA205/06/1780 Institutional research plan: CEZ:AV0Z30460519 Keywords : love waves * phase velocity dispersion * frequency-time analysis Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.326, year: 2011 www.springerlink.com/content/w3149233l60111t1/

  9. Intermittent random walks: transport regimes and implications on search strategies

    International Nuclear Information System (INIS)

    Gomez Portillo, Ignacio; Campos, Daniel; Méndez, Vicenç

    2011-01-01

    We construct a transport model for particles that alternate rests of random duration and flights with random velocities. The model provides a balance equation for the mesoscopic particle density obtained from the continuous-time random walk framework. By assuming power laws for the distributions of waiting times and flight durations (for any velocity distribution with finite moments) we have found that the model can yield all the transport regimes ranging from subdiffusion to ballistic depending on the values of the characteristic exponents of the distributions. In addition, if the exponents satisfy a simple relationship it is shown how the competition between the tails of the distributions gives rise to a diffusive transport. Finally, we explore how the details of this intermittent transport process affect the success probability in an optimal search problem where an individual searcher looks for a target distributed (heterogeneously) in space. All the results are conveniently checked with numerical simulations

  10. Threshold friction velocity of soils within the Columbia Plateau

    Science.gov (United States)

    Wind erosion only occurs when the friction velocity exceeds the threshold friction velocity (TFV) of the surface. The TFV of loessial soils commonly found across the Columbia Plateau region of the U.S. Pacific Northwest is virtually unknown even though these soils are highly erodible and a source of...

  11. Limitations of middle cerebral artery peak systolic velocity in the ...

    African Journals Online (AJOL)

    We present a case of a mother with severe pre-eclampsia at 32 weeks' gestation and non-immune fetal hydrops without obvious cause. Since the. MCA peak systolic velocity (PSV) was ... Limitations of middle cerebral artery peak systolic velocity .... [7] found MCA PSV of value in 9 women with chronic abruption, but in 5.

  12. An Extended Optimal Velocity Model with Consideration of Honk Effect

    International Nuclear Information System (INIS)

    Tang Tieqiao; Li Chuanyao; Huang Haijun; Shang Huayan

    2010-01-01

    Based on the OV (optimal velocity) model, we in this paper present an extended OV model with the consideration of the honk effect. The analytical and numerical results illustrate that the honk effect can improve the velocity and flow of uniform flow but that the increments are relevant to the density. (interdisciplinary physics and related areas of science and technology)

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

    CSIR Research Space (South Africa)

    Rouault, MJ

    2010-01-01

    Full Text Available is known to perform well. Although radial velocities derived from ASAR are on occasion able to represent the measured flow with incredible accuracy, the overall performance of the ASAR radial velocity product is negatively impacted by a few very large...

  14. Measuring velocity by differentiation of analog encoder signals

    NARCIS (Netherlands)

    Winarto, R.F.; Steinbuch, M.; Molengraft, van de M.J.G.

    2013-01-01

    In this report a new method for measuring velocities has been introduced. During the research in literature an overview has been made of the existing methods of measuring velocities. From this research, it can be concluded that a lot of existing approaches only work in specific settings. Besides

  15. Measurement of gas flow velocities by laser-induced gratings

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B; Stampanoni-Panariello, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kozlov, A D.N. [General Physics Institute, Moscow (Russian Federation)

    1999-08-01

    Time resolved light scattering from laser-induced electrostrictive gratings was used for the determination of flow velocities in air at room temperature. By measuring the velocity profile across the width of a slit nozzle we demonstrated the high spatial resolution (about 200 mm) of this novel technique. (author) 3 figs., 1 ref.

  16. Dynamic exercise enhances regional cerebral artery mean flow velocity

    DEFF Research Database (Denmark)

    Linkis, P; Jørgensen, L G; Olesen, H L

    1995-01-01

    Dynamic exercise enhances regional cerebral artery mean flow velocity. J. Appl. Physiol. 78(1): 12-16, 1995.--Anterior (ACA) and middle (MCA) cerebral artery mean flow velocities (Vmean) and pulsatility indexes were determined using transcranial Doppler in 14 subjects during dynamic exercise afte...

  17. Adrenergic regulation of conduction velocity in cultures of immature cardiomyocytes

    NARCIS (Netherlands)

    de Boer, T. P.; van Rijen, H. V. M.; van der Heyden, M. A. G.; de Bakker, J. M. T.; van Veen, T. A. B.

    2008-01-01

    During cardiac maturation, increased exposure of the heart to circulating catecholamines correlates with increased conduction velocity and growth of the heart. We used an in vitro approach to study the underlying mechanisms of adrenergic stimulation induced changes in conduction velocity. By

  18. Determination of hydrogen cluster velocities and comparison with numerical calculations

    International Nuclear Information System (INIS)

    Täschner, A.; Köhler, E.; Ortjohann, H.-W.; Khoukaz, A.

    2013-01-01

    The use of powerful hydrogen cluster jet targets in storage ring experiments led to the need of precise data on the mean cluster velocity as function of the stagnation temperature and pressure for the determination of the volume density of the target beams. For this purpose a large data set of hydrogen cluster velocity distributions and mean velocities was measured at a high density hydrogen cluster jet target using a trumpet shaped nozzle. The measurements have been performed at pressures above and below the critical pressure and for a broad range of temperatures relevant for target operation, e.g., at storage ring experiments. The used experimental method is described which allows for the velocity measurement of single clusters using a time-of-flight technique. Since this method is rather time-consuming and these measurements are typically interfering negatively with storage ring experiments, a method for a precise calculation of these mean velocities was needed. For this, the determined mean cluster velocities are compared with model calculations based on an isentropic one-dimensional van der Waals gas. Based on the obtained data and the presented numerical calculations, a new method has been developed which allows to predict the mean cluster velocities with an accuracy of about 5%. For this two cut-off parameters defining positions inside the nozzle are introduced, which can be determined for a given nozzle by only two velocity measurements

  19. Measuring Average Angular Velocity with a Smartphone Magnetic Field Sensor

    Science.gov (United States)

    Pili, Unofre; Violanda, Renante

    2018-01-01

    The angular velocity of a spinning object is, by standard, measured using a device called a tachometer. However, by directly using it in a classroom setting, the activity is likely to appear as less instructive and less engaging. Indeed, some alternative classroom-suitable methods for measuring angular velocity have been presented. In this paper,…

  20. Doppler velocity measurements from large and small arteries of mice

    Science.gov (United States)

    Reddy, Anilkumar K.; Madala, Sridhar; Entman, Mark L.; Michael, Lloyd H.; Taffet, George E.

    2011-01-01

    With the growth of genetic engineering, mice have become increasingly common as models of human diseases, and this has stimulated the development of techniques to assess the murine cardiovascular system. Our group has developed nonimaging and dedicated Doppler techniques for measuring blood velocity in the large and small peripheral arteries of anesthetized mice. We translated technology originally designed for human vessels for use in smaller mouse vessels at higher heart rates by using higher ultrasonic frequencies, smaller transducers, and higher-speed signal processing. With these methods one can measure cardiac filling and ejection velocities, velocity pulse arrival times for determining pulse wave velocity, peripheral blood velocity and vessel wall motion waveforms, jet velocities for the calculation of the pressure drop across stenoses, and left main coronary velocity for the estimation of coronary flow reserve. These noninvasive methods are convenient and easy to apply, but care must be taken in interpreting measurements due to Doppler sample volume size and angle of incidence. Doppler methods have been used to characterize and evaluate numerous cardiovascular phenotypes in mice and have been particularly useful in evaluating the cardiac and vascular remodeling that occur following transverse aortic constriction. Although duplex ultrasonic echo-Doppler instruments are being applied to mice, dedicated Doppler systems are more suitable for some applications. The magnitudes and waveforms of blood velocities from both cardiac and peripheral sites are similar in mice and humans, such that much of what is learned using Doppler technology in mice may be translated back to humans. PMID:21572013

  1. Magnetic and Velocity Field Variations in the Active Regions NOAA ...

    Indian Academy of Sciences (India)

    Abstract. We study the magnetic and velocity field evolution in the two magnetically complex active regions NOAA 10486 and NOAA 10488 observed during October–November 2003. We have used the available data to examine net flux and Doppler velocity time profiles to identify changes associated with evolutionary and ...

  2. Development of vortex model with realistic axial velocity distribution

    International Nuclear Information System (INIS)

    Ito, Kei; Ezure, Toshiki; Ohshima, Hiroyuki

    2014-01-01

    A vortex is considered as one of significant phenomena which may cause gas entrainment (GE) and/or vortex cavitation in sodium-cooled fast reactors. In our past studies, the vortex is assumed to be approximated by the well-known Burgers vortex model. However, the Burgers vortex model has a simple but unreal assumption that the axial velocity component is horizontally constant, while in real the free surface vortex has the axial velocity distribution which shows large gradient in radial direction near the vortex center. In this study, a new vortex model with realistic axial velocity distribution is proposed. This model is derived from the steady axisymmetric Navier-Stokes equation as well as the Burgers vortex model, but the realistic axial velocity distribution in radial direction is considered, which is defined to be zero at the vortex center and to approach asymptotically to zero at infinity. As the verification, the new vortex model is applied to the evaluation of a simple vortex experiment, and shows good agreements with the experimental data in terms of the circumferential velocity distribution and the free surface shape. In addition, it is confirmed that the Burgers vortex model fails to calculate accurate velocity distribution with the assumption of uniform axial velocity. However, the calculation accuracy of the Burgers vortex model can be enhanced close to that of the new vortex model in consideration of the effective axial velocity which is calculated as the average value only in the vicinity of the vortex center. (author)

  3. Wave Tank Studies of Phase Velocities of Short Wind Waves

    Science.gov (United States)

    Ermakov, S.; Sergievskaya, I.; Shchegolkov, Yu.

    Wave tank studies of phase velocities of short wind waves have been carried out using Ka-band radar and an Optical Spectrum Analyser. The phase velocities were retrieved from measured radar and optical Doppler shifts, taking into account measurements of surface drift velocities. The dispersion relationship was studied in centimetre (cm)- and millimetre(mm)-scale wavelength ranges at different fetches and wind speeds, both for a clean water surface and for water covered with surfactant films. It is ob- tained that the phase velocities do not follow the dispersion relation of linear capillary- gravity waves, increasing with fetch and, therefore, depending on phase velocities of dominant decimetre (dm)-centimetre-scale wind waves. One thus can conclude that nonlinear cm-mm-scale harmonics bound to the dominant wind waves and propagat- ing with the phase velocities of the decimetric waves are present in the wind wave spectrum. The resulting phase velocities of short wind waves are determined by re- lation between free and bound waves. The relative intensity of the bound waves in the spectrum of short wind waves is estimated. It is shown that this relation depends strongly on the surfactant concentration, because the damping effect due to films is different for free and bound waves; this results to changes of phase velocities of wind waves in the presence of surfactant films. This work was supported by MOD, UK via DERA Winfrith (Project ISTC 1774P) and by RFBR (Project 02-05-65102).

  4. The geostrophic velocity field in shallow water over topography

    Science.gov (United States)

    Charnock, Henry; Killworth, Peter D.

    1998-01-01

    A recent note (Hopkins, T.S., 1996. A note on the geostrophic velocity field referenced to a point. Continental Shelf Research 16, 1621-1630) suggests a method for evaluating absolute pressure gradients in stratified water over topography. We demonstrate that this method requires no along-slope bottom velocity, in contradiction to what is usually observed, and that mass is not conserved.

  5. Phase velocity enhancement of linear explosive shock tubes

    Science.gov (United States)

    Loiseau, Jason; Serge, Matthew; Szirti, Daniel; Higgins, Andrew; Tanguay, Vincent

    2011-06-01

    Strong, high density shocks can be generated by sequentially detonating a hollow cylinder of explosives surrounding a thin-walled, pressurized tube. Implosion of the tube results in a pinch that travels at the detonation velocity of the explosive and acts like a piston to drive a shock into the gas ahead of it. In order to increase the maximum shock velocities that can be obtained, a phase velocity generator can be used to drag an oblique detonation wave along the gas tube at a velocity much higher than the base detonation velocity of the explosive. Since yielding and failure of the gas tube is the primary limitation of these devices, it is desirable to retain the dynamic confinement effects of a heavy-walled tamper without interfering with operation of the phase velocity generator. This was accomplished by cutting a slit into the tamper and introducing a phased detonation wave such that it asymmetrically wraps around the gas tube. This type of configuration has been previously experimentally verified to produce very strong shocks but the post-shock pressure and shock velocity limits have not been investigated. This study measured the shock trajectory for various fill pressures and phase velocities to ascertain the limiting effects of tube yield, detonation obliquity and pinch aspect ratio.

  6. Genetic analysis of peripheral nerve conduction velocity in twins

    NARCIS (Netherlands)

    Rijsdijk, F.V.; Boomsma, D.I.; Vernon, P.A.

    1995-01-01

    We studied variation in peripheral nerve conduction velocity (PNCV) and intelligence in a group of 16-year-old Dutch twins. It has been suggested that both brain nerve conduction velocity and PNCV are positively correlated with intelligence (Reed, 1984) and that heritable differences in NCV may

  7. Subsurface offset behaviour in velocity analysis with extended reflectivity images

    NARCIS (Netherlands)

    Mulder, W.A.

    2012-01-01

    Migration velocity analysis with the wave equation can be accomplished by focusing of extended migration images, obtained by introducing a subsurface offset or shift. A reflector in the wrong velocity model will show up as a curve in the extended image. In the correct model, it should collapse to a

  8. Subsurface offset behaviour in velocity analysis with extended reflectivity images

    NARCIS (Netherlands)

    Mulder, W.A.

    2013-01-01

    Migration velocity analysis with the constant-density acoustic wave equation can be accomplished by the focusing of extended migration images, obtained by introducing a subsurface shift in the imaging condition. A reflector in a wrong velocity model will show up as a curve in the extended image. In

  9. Climate change velocity underestimates climate change exposure in mountainous regions

    Science.gov (United States)

    Solomon Z. Dobrowski; Sean A. Parks

    2016-01-01

    Climate change velocity is a vector depiction of the rate of climate displacement used for assessing climate change impacts. Interpreting velocity requires an assumption that climate trajectory length is proportional to climate change exposure; longer paths suggest greater exposure. However, distance is an imperfect measure of exposure because it does not...

  10. Calculation of projectile velocity in an electromagnetic mass driver

    International Nuclear Information System (INIS)

    Ikuta, K.

    1986-08-01

    The formula for the velocity increase of a projectile accelerated by the single z-pinch between the cylindrical electrodes is established. This formula enables one to consider the necessary stages in the cylindrical electrode array of the accelerator for a required velocity. (author)

  11. Estimating 2-D Vector Velocities Using Multidimensional Spectrum Analysis

    DEFF Research Database (Denmark)

    Oddershede, Niels; Løvstakken, Lasse; Torp, Hans

    2008-01-01

    new velocity estimators for finding both the axial and lateral velocity components. The estimators essentially search for the plane in the 3-D Fourier space, where the integrated power spectrum is largest. The first uses the 3-D Fourier transform to find the power spectrum, while the second uses...

  12. Fat mass measured by DXA varies with scan velocity

    DEFF Research Database (Denmark)

    Black, Eva; Petersen, Liselotte; Kreutzer, Martin

    2002-01-01

    To study the influence of scan velocities of DXA on the measured size of fat mass, lean body mass, bone mineral content and density, and total body weight.......To study the influence of scan velocities of DXA on the measured size of fat mass, lean body mass, bone mineral content and density, and total body weight....

  13. Hydrocarbon saturation determination using acoustic velocities obtained through casing

    Science.gov (United States)

    Moos, Daniel

    2010-03-09

    Compressional and shear velocities of earth formations are measured through casing. The determined compressional and shear velocities are used in a two component mixing model to provides improved quantitative values for the solid, the dry frame, and the pore compressibility. These are used in determination of hydrocarbon saturation.

  14. Altered velocity processing in schizophrenia during pursuit eye tracking.

    Directory of Open Access Journals (Sweden)

    Matthias Nagel

    Full Text Available Smooth pursuit eye movements (SPEM are needed to keep the retinal image of slowly moving objects within the fovea. Depending on the task, about 50%-80% of patients with schizophrenia have difficulties in maintaining SPEM. We designed a study that comprised different target velocities as well as testing for internal (extraretinal guidance of SPEM in the absence of a visual target. We applied event-related fMRI by presenting four velocities (5, 10, 15, 20°/s both with and without intervals of target blanking. 17 patients and 16 healthy participants were included. Eye movements were registered during scanning sessions. Statistical analysis included mixed ANOVAs and regression analyses of the target velocity on the Blood Oxygen Level Dependency (BOLD signal. The main effect group and the interaction of velocity×group revealed reduced activation in V5 and putamen but increased activation of cerebellar regions in patients. Regression analysis showed that activation in supplementary eye field, putamen, and cerebellum was not correlated to target velocity in patients in contrast to controls. Furthermore, activation in V5 and in intraparietal sulcus (putative LIP bilaterally was less strongly correlated to target velocity in patients than controls. Altered correlation of target velocity and neural activation in the cortical network supporting SPEM (V5, SEF, LIP, putamen implies impaired transformation of the visual motion signal into an adequate motor command in patients. Cerebellar regions seem to be involved in compensatory mechanisms although cerebellar activity in patients was not related to target velocity.

  15. Calibrating the Planck Cluster Mass Scale with Cluster Velocity Dispersions

    Science.gov (United States)

    Amodeo, Stefania; Mei, Simona; Stanford, Spencer A.; Bartlett, James G.; Melin, Jean-Baptiste; Lawrence, Charles R.; Chary, Ranga-Ram; Shim, Hyunjin; Marleau, Francine; Stern, Daniel

    2017-08-01

    We measure the Planck cluster mass bias using dynamical mass measurements based on velocity dispersions of a subsample of 17 Planck-detected clusters. The velocity dispersions were calculated using redshifts determined from spectra that were obtained at the Gemini observatory with the GMOS multi-object spectrograph. We correct our estimates for effects due to finite aperture, Eddington bias, and correlated scatter between velocity dispersion and the Planck mass proxy. The result for the mass bias parameter, (1-b), depends on the value of the galaxy velocity bias, {b}{{v}}, adopted from simulations: (1-b)=(0.51+/- 0.09){b}{{v}}3. Using a velocity bias of {b}{{v}}=1.08 from Munari et al., we obtain (1-b)=0.64+/- 0.11, I.e., an error of 17% on the mass bias measurement with 17 clusters. This mass bias value is consistent with most previous weak-lensing determinations. It lies within 1σ of the value that is needed to reconcile the Planck cluster counts with the Planck primary cosmic microwave background constraints. We emphasize that uncertainty in the velocity bias severely hampers the precision of the measurements of the mass bias using velocity dispersions. On the other hand, when we fix the Planck mass bias using the constraints from Penna-Lima et al., based on weak-lensing measurements, we obtain a positive velocity bias of {b}{{v}}≳ 0.9 at 3σ .

  16. Measuring Velocity and Acceleration Using Doppler Shift of a ...

    Indian Academy of Sciences (India)

    to be used to measure its velocity and acceleration. We also apply this method, as an example here, to spectral lines of the blue-shifted jet in micro-quasar SS433 and discuss the intricacies of these measurements. Key words. Doppler effect—measuring velocity and acceleration of the source— jet in SS433. 1. Introduction.

  17. Reliability of force-velocity relationships during deadlift high pull.

    Science.gov (United States)

    Lu, Wei; Boyas, Sébastien; Jubeau, Marc; Rahmani, Abderrahmane

    2017-11-13

    This study aimed to evaluate the within- and between-session reliability of force, velocity and power performances and to assess the force-velocity relationship during the deadlift high pull (DHP). Nine participants performed two identical sessions of DHP with loads ranging from 30 to 70% of body mass. The force was measured by a force plate under the participants' feet. The velocity of the 'body + lifted mass' system was calculated by integrating the acceleration and the power was calculated as the product of force and velocity. The force-velocity relationships were obtained from linear regression of both mean and peak values of force and velocity. The within- and between-session reliability was evaluated by using coefficients of variation (CV) and intraclass correlation coefficients (ICC). Results showed that DHP force-velocity relationships were significantly linear (R² > 0.90, p  0.94), mean and peak velocities showed a good agreement (CV reliable and can therefore be utilised as a tool to characterise individuals' muscular profiles.

  18. Helicity and evanescent waves. [Energy transport velocity, helicity, Lorentz transformation

    Energy Technology Data Exchange (ETDEWEB)

    Agudin, J L; Platzeck, A M [La Plata Univ. Nacional (Argentina); Albano, J R [Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina

    1978-02-20

    It is shown that the projection of the angular momentum of a circularly polarized electromagnetic evanescent wave along the mean velocity of energy transport (=helicity) can be reverted by a Lorentz transformation, in spite of the fact that this velocity is c.

  19. Video Measurement of the Muzzle Velocity of a Potato Gun

    Science.gov (United States)

    Jasperson, Christopher; Pollman, Anthony

    2011-01-01

    Using first principles, a theoretical equation for the maximum and actual muzzle velocities for a pneumatic cannon was recently derived. For a fixed barrel length, this equation suggests that the muzzle velocity can be enhanced by maximizing the product of the initial pressure and the volume of the propellant gas and decreasing the projectile…

  20. On an illusion of superluminal velocities produced by gravitational lenses

    International Nuclear Information System (INIS)

    Ingel, L.Kh.

    1981-01-01

    It is noted that gravitational lenses, by focusing the radiation of an object, increase the angle which it subtends. This in turn produces the illusion of an increase in velocities at right angles to the line of sight. Preliminary estimates are made which indicate a rather high probability of strong distortion of the observed velocities

  1. A classical model explaining the OPERA velocity paradox

    CERN Document Server

    Broda, Boguslaw

    2011-01-01

    In the context of the paradoxical results of the OPERA Collaboration, we have proposed a classical mechanics model yielding the statistically measured velocity of a beam higher than the velocity of the particles constituting the beam. Ingredients of our model necessary to obtain this curious result are a non-constant fraction function and the method of the maximum-likelihood estimation.

  2. Plasma flow velocity measurements using a modulated Michelson interferometer

    NARCIS (Netherlands)

    Howard, J.; Meijer, F. G.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (C) 1997 Elsevier Science S.A.

  3. New technology - demonstration of a vector velocity technique

    DEFF Research Database (Denmark)

    Møller Hansen, Peter; Pedersen, Mads M; Hansen, Kristoffer L

    2011-01-01

    With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60-70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa...

  4. On the origin of high-velocity runaway stars

    NARCIS (Netherlands)

    Gvaramadze, V.V.; Gualandris, A.; Portegies Zwart, S.

    2009-01-01

    We explore the hypothesis that some high-velocity runaway stars attain their peculiar velocities in the course of exchange encounters between hard massive binaries and a very massive star (either an ordinary 50-100 M-circle dot star or a more massive one, formed through runaway mergers of ordinary

  5. High-velocity runaway stars from three-body encounters

    Science.gov (United States)

    Gvaramadze, V. V.; Gualandris, A.; Portegies Zwart, S.

    2010-01-01

    We performed numerical simulations of dynamical encounters between hard, massive binaries and a very massive star (VMS; formed through runaway mergers of ordinary stars in the dense core of a young massive star cluster) to explore the hypothesis that this dynamical process could be responsible for the origin of high-velocity (≥ 200 - 400 km s-1) early or late B-type stars. We estimated the typical velocities produced in encounters between very tight massive binaries and VMSs (of mass of ≥ 200 M⊙) and found that about 3 - 4% of all encounters produce velocities ≥ 400 km s-1, while in about 2% of encounters the escapers attain velocities exceeding the Milky Ways's escape velocity. We therefore argue that the origin of high-velocity (≥ 200 - 400 km s-1) runaway stars and at least some so-called hypervelocity stars could be associated with dynamical encounters between the tightest massive binaries and VMSs formed in the cores of star clusters. We also simulated dynamical encounters between tight massive binaries and single ordinary 50 - 100 M⊙ stars. We found that from 1 to ≃ 4% of these encounters can produce runaway stars with velocities of ≥ 300 - 400 km s-1 (typical of the bound population of high-velocity halo B-type stars) and occasionally (in less than 1% of encounters) produce hypervelocity (≥ 700 km s-1) late B-type escapers.

  6. Pressure and velocity dependence of flow-type cavitation erosion

    CSIR Research Space (South Africa)

    Auret, JG

    1993-12-01

    Full Text Available Previous results on the influence of water pressure and velocity on flow-type cavitations erosion, i.e. an increase in erosion rate with increasing velocity and peaking of erosion rate as a function of pressure, were confirmed by measurements with a...

  7. Velocity-space sensitivity of neutron spectrometry measurements

    DEFF Research Database (Denmark)

    Jacobsen, Asger Schou; Salewski, Mirko; Eriksson, J.

    2015-01-01

    Neutron emission spectrometry (NES) measures the energies of neutrons produced in fusion reactions. Here we present velocity-space weight functions for NES and neutron yield measurements. Weight functions show the sensitivity as well as the accessible regions in velocity space for a given range...

  8. SIMULATIONS OF HIGH-VELOCITY CLOUDS. I. HYDRODYNAMICS AND HIGH-VELOCITY HIGH IONS

    International Nuclear Information System (INIS)

    Kwak, Kyujin; Henley, David B.; Shelton, Robin L.

    2011-01-01

    We present hydrodynamic simulations of high-velocity clouds (HVCs) traveling through the hot, tenuous medium in the Galactic halo. A suite of models was created using the FLASH hydrodynamics code, sampling various cloud sizes, densities, and velocities. In all cases, the cloud-halo interaction ablates material from the clouds. The ablated material falls behind the clouds where it mixes with the ambient medium to produce intermediate-temperature gas, some of which radiatively cools to less than 10,000 K. Using a non-equilibrium ionization algorithm, we track the ionization levels of carbon, nitrogen, and oxygen in the gas throughout the simulation period. We present observation-related predictions, including the expected H I and high ion (C IV, N V, and O VI) column densities on sightlines through the clouds as functions of evolutionary time and off-center distance. The predicted column densities overlap those observed for Complex C. The observations are best matched by clouds that have interacted with the Galactic environment for tens to hundreds of megayears. Given the large distances across which the clouds would travel during such time, our results are consistent with Complex C having an extragalactic origin. The destruction of HVCs is also of interest; the smallest cloud (initial mass ∼ 120 M sun ) lost most of its mass during the simulation period (60 Myr), while the largest cloud (initial mass ∼ 4 x 10 5 M sun ) remained largely intact, although deformed, during its simulation period (240 Myr).

  9. Extremal inversion of lunar travel time data. [seismic velocity structure

    Science.gov (United States)

    Burkhard, N.; Jackson, D. D.

    1975-01-01

    The tau method, developed by Bessonova et al. (1974), of inversion of travel times is applied to lunar P-wave travel time data to find limits on the velocity structure of the moon. Tau is the singular solution to the Clairaut equation. Models with low-velocity zones, with low-velocity zones at differing depths, and without low-velocity zones, were found to be consistent with data and within the determined limits. Models with and without a discontinuity at about 25-km depth have been found which agree with all travel time data to within two standard deviations. In other words, the existence of the discontinuity and its size and location have not been uniquely resolved. Models with low-velocity channels are also possible.

  10. Flood Water Crossing: Laboratory Model Investigations for Water Velocity Reductions

    Directory of Open Access Journals (Sweden)

    Kasnon N.

    2014-01-01

    Full Text Available The occurrence of floods may give a negative impact towards road traffic in terms of difficulties in mobilizing traffic as well as causing damage to the vehicles, which later cause them to be stuck in the traffic and trigger traffic problems. The high velocity of water flows occur when there is no existence of objects capable of diffusing the water velocity on the road surface. The shape, orientation and size of the object to be placed beside the road as a diffuser are important for the effective flow attenuation of water. In order to investigate the water flow, a laboratory experiment was set up and models were constructed to study the flow velocity reduction. The velocity of water before and after passing through the diffuser objects was investigated. This paper focuses on laboratory experiments to determine the flow velocity of the water using sensors before and after passing through two best diffuser objects chosen from a previous flow pattern experiment.

  11. Particle velocity measurements in laser irradiated foils using ORVIS

    International Nuclear Information System (INIS)

    Sheffield, S.A.; Fisk, G.A.

    1983-01-01

    Aluminum foils from 2- to 200-μm thick have been subjected to a Nd:YAG laser pulse of low irradiance (10 9 W/cm 2 , approx. 10 ns pulse) to produce laser-driven shocks in the foils. The particle velocity history of the foil side opposite the laser deposition was monitored with nanosecond resolution by a velocity interferometer system called ORVIS. These histories indicate a shock reverberation process accelerates the foil. Peak foil velocities can be adequately calculated using a ricket propulsion model developed from experiments at much higher irradiances. A velocity of 1 km/s was developed in a 2-μm-thick free foil in a time of 50 ns. Water-confined foils attained peak particle velocities about three times higher than those of free foils

  12. Doppler Lidar Vertical Velocity Statistics Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    Accurate height-resolved measurements of higher-order statistical moments of vertical velocity fluctuations are crucial for improved understanding of turbulent mixing and diffusion, convective initiation, and cloud life cycles. The Atmospheric Radiation Measurement (ARM) Climate Research Facility operates coherent Doppler lidar systems at several sites around the globe. These instruments provide measurements of clear-air vertical velocity profiles in the lower troposphere with a nominal temporal resolution of 1 sec and height resolution of 30 m. The purpose of the Doppler lidar vertical velocity statistics (DLWSTATS) value-added product (VAP) is to produce height- and time-resolved estimates of vertical velocity variance, skewness, and kurtosis from these raw measurements. The VAP also produces estimates of cloud properties, including cloud-base height (CBH), cloud frequency, cloud-base vertical velocity, and cloud-base updraft fraction.

  13. Evolution of velocity dispersion along cold collisionless flows

    International Nuclear Information System (INIS)

    Banik, Nilanjan; Sikivie, Pierre

    2016-01-01

    We found that the infall of cold dark matter onto a galaxy produces cold collisionless flows and caustics in its halo. If a signal is found in the cavity detector of dark matter axions, the flows will be readily apparent as peaks in the energy spectrum of photons from axion conversion, allowing the densities, velocity vectors and velocity dispersions of the flows to be determined. We also discuss the evolution of velocity dispersion along cold collisionless flows in one and two dimensions. A technique is presented for obtaining the leading behaviour of the velocity dispersion near caustics. The results are used to derive an upper limit on the energy dispersion of the Big Flow from the sharpness of its nearby caustic, and a prediction for the dispersions in its velocity components

  14. Dielectric haloscopes: sensitivity to the axion dark matter velocity

    Energy Technology Data Exchange (ETDEWEB)

    Millar, Alexander J.; Redondo, Javier; Steffen, Frank D., E-mail: millar@mpp.mpg.de, E-mail: jredondo@unizar.es, E-mail: steffen@mpp.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany)

    2017-10-01

    We study the effect of the axion dark matter velocity in the recently proposed dielectric haloscopes, a promising avenue to search for well-motivated high mass (40–400 μeV) axions. We describe non-zero velocity effects for axion-photon mixing in a magnetic field and for the phenomenon of photon emission from interfaces between different dielectric media. As velocity effects are only important when the haloscope is larger than about 20% of the axion de Broglie wavelength, for the planned MADMAX experiment with 80 dielectric disks the velocity dependence can safely be neglected. However, an augmented MADMAX or a second generation experiment would be directionally sensitive to the axion velocity, and thus a sensitive measure of axion astrophysics.

  15. Velocity slip of gas mixtures in free jet expansions

    International Nuclear Information System (INIS)

    Cattolica, R.J.; Talbot, L.; Coe, D.

    1976-11-01

    Velocity slip in gas mixtures of argon and helium in axisymmetric free jet expansions has been measured using a grating monochromator together with a computer-controlled Fabry-Perot interferometer to observe the fluorescence excited by an electron beam. The Doppler shift between the fluorescence observed parallel and perpendicular to the centerline of the free jet was used to measure the mean velocity of a particular species along the jet centerline, employing the 4880 A line for argon and the 5016 A line for helium. By alternately tracking the parallel and perpendicular fluorescence, the Doppler shift due to the mean velocity was measured directly with an accuracy of 1 percent. Flow field surveys have been made in the initial acceleration region where the flow becomes hypersonic and in the far field region. The differences between argon and helium mean velocities (velocity slip) are in good agreement with molecular beam data and show a correlation with an inverse Knudsen number

  16. Velocity Dispersion of Ionized Gas and Multiple Supernova Explosions

    Directory of Open Access Journals (Sweden)

    Vasiliev E. O.

    2015-06-01

    Full Text Available We use 3D numerical simulations to study the evolution of the Hα intensity and velocity dispersion for single and multiple supernova (SN explosions. We find that the IHα– σ diagram obtained for simulated gas flows is similar in shape to that observed in dwarf galaxies. We conclude that colliding SN shells with significant difference in age are responsible for high velocity dispersion that reaches up to ≳ 100 km s−1. Such a high velocity dispersion could be hardly obtained for a single SN remnant. Peaks of velocity dispersion in the IHα– σ diagram may correspond to several isolated or merged SN remnants with moderately different ages. Degrading the spatial resolution in the Hα intensity and velocity dispersion maps makes the simulated IHα– σ diagrams close to those observed in dwarf galaxies not only in shape, but also quantitatively.

  17. Wave velocity characteristic for Kenaf natural fibre under impact damage

    Science.gov (United States)

    Zaleha, M.; Mahzan, S.; Fitri, Muhamad; Kamarudin, K. A.; Eliza, Y.; Tobi, A. L. Mohd

    2017-01-01

    This paper aims to determining the wave velocity characteristics for kenaf fibre reinforced composite (KFC) and it includes both experimental and simulation results. Lead zirconate titanate (PZT) sensor were proposed to be positioned to corresponding locations on the panel. In order to demonstrate the wave velocity, an impacts was introduced onto the panel. It is based on a classical sensor triangulation methodology, combines with experimental strain wave velocity analysis. Then the simulation was designed to replicate panel used in the experimental impacts test. This simulation was carried out using ABAQUS. It was shown that the wave velocity propagates faster in the finite element simulation. Although the experimental strain wave velocity and finite element simulation results do not match exactly, the shape of both waves is similar.

  18. Leading-Edge Velocities and Lifted Methane Jet Flame Stability

    Directory of Open Access Journals (Sweden)

    W. Wang

    2010-01-01

    Full Text Available Current interest exists in understanding reaction-zone dynamics and mechanisms with respect to how they counterpropagate against incoming reactants. Images of flame position and flow-field morphology are presented from flame chemiluminescence and particle image velocimetry (PIV measurements. In the present study, PIV experiments were carried out to measure the methane jet lifted-flame flow-field velocities in the vicinity of the flame leading edge. Specifically, velocity fields within the high-temperature zone were examined in detail, which complements previous studies, whose prime focus is the flow-field upstream of the high-temperature boundary. PIV data is used not only to determine the velocities, but, along with chemiluminescence images, to also indicate the approximate location of the reaction zone (further supported by/through the leading-edge flame velocity distributions. The velocity results indirectly support the concept that the flame is anchored primarily through the mechanism of partially premixed flame propagation.

  19. Cognitive regulation of saccadic velocity by reward prospect.

    Science.gov (United States)

    Chen, Lewis L; Hung, Leroy Y; Quinet, Julie; Kosek, Kevin

    2013-08-01

    It is known that expectation of reward speeds up saccades. Past studies have also shown the presence of a saccadic velocity bias in the orbit, resulting from a biomechanical regulation over varying eccentricities. Nevertheless, whether and how reward expectation interacts with the biomechanical regulation of saccadic velocities over varying eccentricities remains unknown. We addressed this question by conducting a visually guided double-step saccade task. The role of reward expectation was tested in monkeys performing two consecutive horizontal saccades, one associated with reward prospect and the other not. To adequately assess saccadic velocity and avoid adaptation, we systematically varied initial eye positions, saccadic directions and amplitudes. Our results confirmed the existence of a velocity bias in the orbit, i.e., saccadic peak velocity decreased linearly as the initial eye position deviated in the direction of the saccade. The slope of this bias increased as saccadic amplitudes increased. Nevertheless, reward prospect facilitated velocity to a greater extent for saccades away from than for saccades toward the orbital centre, rendering an overall reduction in the velocity bias. The rate (slope) and magnitude (intercept) of reward modulation over this velocity bias were linearly correlated with amplitudes, similar to the amplitude-modulated velocity bias without reward prospect, which presumably resulted from a biomechanical regulation. Small-amplitude (≤ 5°) saccades received little modulation. These findings together suggest that reward expectation modulated saccadic velocity not as an additive signal but as a facilitating mechanism that interacted with the biomechanical regulation. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  20. Effects of 12-week overground walking training at ventilatory threshold velocity in type 2 diabetic women.

    Science.gov (United States)

    Belli, Taisa; Ribeiro, Luiz Fernando Paulino; Ackermann, Marco Aurélio; Baldissera, Vilmar; Gobatto, Claudio Alexandre; Galdino da Silva, Rozinaldo

    2011-09-01

    This study analyzed the effects of overground walking training at ventilatory threshold (VT) velocity on glycaemic control, body composition, physical fitness and lipid profile in DM2 women. Nineteen sedentary patients were randomly assigned to a control group (CG; n=10, 55.9±2.2 years) or a trained group (TG; n=9, 53.4±2.3 years). Both groups were subjected to anthropometric measures, a 12-h fasting blood sampling and a graded treadmill exercise test at baseline and after a 12-week period, during which TG followed a training program involving overground walking at VT velocity for 20-60min/session three times/week. Significant group×time interactions (P0.05) in fasting blood glucose, submaximal fitness parameters and lipid profile. Our results suggest that overground walking training at VT velocity improves long term glycaemic control, body composition and exercise capacity, attesting for the relevance of this parameter as an effective strategy for the exercise intensity prescription in DM2 population. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  1. Instantaneous ballistic velocity of suspended Brownian nanocrystals measured by upconversion nanothermometry

    Science.gov (United States)

    Brites, Carlos D. S.; Xie, Xiaoji; Debasu, Mengistie L.; Qin, Xian; Chen, Runfeng; Huang, Wei; Rocha, João; Liu, Xiaogang; Carlos, Luís D.

    2016-10-01

    Brownian motion is one of the most fascinating phenomena in nature. Its conceptual implications have a profound impact in almost every field of science and even economics, from dissipative processes in thermodynamic systems, gene therapy in biomedical research, artificial motors and galaxy formation to the behaviour of stock prices. However, despite extensive experimental investigations, the basic microscopic knowledge of prototypical systems such as colloidal particles in a fluid is still far from being complete. This is particularly the case for the measurement of the particles' instantaneous velocities, elusive due to the rapid random movements on extremely short timescales. Here, we report the measurement of the instantaneous ballistic velocity of Brownian nanocrystals suspended in both aqueous and organic solvents. To achieve this, we develop a technique based on upconversion nanothermometry. We find that the population of excited electronic states in NaYF4:Yb/Er nanocrystals at thermal equilibrium can be used for temperature mapping of the nanofluid with great thermal sensitivity (1.15% K-1 at 296 K) and a high spatial resolution (<1 μm). A distinct correlation between the heat flux in the nanofluid and the temporal evolution of Er3+ emission allows us to measure the instantaneous velocity of nanocrystals with different sizes and shapes.

  2. Anomalous diffusion and q-Weibull velocity distributions in epithelial cell migration.

    Directory of Open Access Journals (Sweden)

    Tatiane Souza Vilela Podestá

    Full Text Available In multicellular organisms, cell motility is central in all morphogenetic processes, tissue maintenance, wound healing and immune surveillance. Hence, the control of cell motion is a major demand in the creation of artificial tissues and organs. Here, cell migration assays on plastic 2D surfaces involving normal (MDCK and tumoral (B16F10 epithelial cell lines were performed varying the initial density of plated cells. Through time-lapse microscopy quantities such as speed distributions, velocity autocorrelations and spatial correlations, as well as the scaling of mean-squared displacements were determined. We find that these cells exhibit anomalous diffusion with q-Weibull speed distributions that evolves non-monotonically to a Maxwellian distribution as the initial density of plated cells increases. Although short-ranged spatial velocity correlations mark the formation of small cell clusters, the emergence of collective motion was not observed. Finally, simulational results from a correlated random walk and the Vicsek model of collective dynamics evidence that fluctuations in cell velocity orientations are sufficient to produce q-Weibull speed distributions seen in our migration assays.

  3. Evaluation of interlayer interfacial stiffness and layer wave velocity of multilayered structures by ultrasonic spectroscopy.

    Science.gov (United States)

    Ishii, Yosuke; Biwa, Shiro

    2014-07-01

    An ultrasonic evaluation procedure for the interlayer interfacial normal stiffness and the intralayer longitudinal wave velocity of multilayered plate-like structures is proposed. Based on the characteristics of the amplitude reflection spectrum of ultrasonic wave at normal incidence to a layered structure with spring-type interlayer interfaces, it is shown that the interfacial normal stiffness and the longitudinal wave velocity in the layers can be simultaneously evaluated from the frequencies of local maxima and minima of the spectrum provided that all interfaces and layers have the same properties. The effectiveness of the proposed procedure is investigated from the perspective of the sensitivity of local extremal frequencies of the reflection spectrum. The feasibility of the proposed procedure is also investigated when the stiffness of each interface is subjected to small random fluctuations about a certain average value. The proposed procedure is applied to a 16-layered cross-ply carbon-fiber-reinforced composite laminate. The normal stiffness of resin-rich interfaces and the longitudinal wave velocity of plies in the thickness direction evaluated from the experimental reflection spectrum are shown to be consistent with simple theoretical estimations.

  4. Update schemes of multi-velocity floor field cellular automaton for pedestrian dynamics

    Science.gov (United States)

    Luo, Lin; Fu, Zhijian; Cheng, Han; Yang, Lizhong

    2018-02-01

    Modeling pedestrian movement is an interesting problem both in statistical physics and in computational physics. Update schemes of cellular automaton (CA) models for pedestrian dynamics govern the schedule of pedestrian movement. Usually, different update schemes make the models behave in different ways, which should be carefully recalibrated. Thus, in this paper, we investigated the influence of four different update schemes, namely parallel/synchronous scheme, random scheme, order-sequential scheme and shuffled scheme, on pedestrian dynamics. The multi-velocity floor field cellular automaton (FFCA) considering the changes of pedestrians' moving properties along walking paths and heterogeneity of pedestrians' walking abilities was used. As for parallel scheme only, the collisions detection and resolution should be considered, resulting in a great difference from any other update schemes. For pedestrian evacuation, the evacuation time is enlarged, and the difference in pedestrians' walking abilities is better reflected, under parallel scheme. In face of a bottleneck, for example a exit, using a parallel scheme leads to a longer congestion period and a more dispersive density distribution. The exit flow and the space-time distribution of density and velocity have significant discrepancies under four different update schemes when we simulate pedestrian flow with high desired velocity. Update schemes may have no influence on pedestrians in simulation to create tendency to follow others, but sequential and shuffled update scheme may enhance the effect of pedestrians' familiarity with environments.

  5. Rayleigh wave group velocity and shear wave velocity structure in the San Francisco Bay region from ambient noise tomography

    Science.gov (United States)

    Li, Peng; Thurber, Clifford

    2018-06-01

    We derive new Rayleigh wave group velocity models and a 3-D shear wave velocity model of the upper crust in the San Francisco Bay region using an adaptive grid ambient noise tomography algorithm and 6 months of continuous seismic data from 174 seismic stations from multiple networks. The resolution of the group velocity models is 0.1°-0.2° for short periods (˜3 s) and 0.3°-0.4° for long periods (˜10 s). The new shear wave velocity model of the upper crust reveals a number of important structures. We find distinct velocity contrasts at the Golden Gate segment of the San Andreas Fault, the West Napa Fault, central part of the Hayward Fault and southern part of the Calaveras Fault. Low shear wave velocities are mainly located in Tertiary and Quaternary basins, for instance, La Honda Basin, Livermore Valley and the western and eastern edges of Santa Clara Valley. Low shear wave velocities are also observed at the Sonoma volcanic field. Areas of high shear wave velocity include the Santa Lucia Range, the Gabilan Range and Ben Lomond Plutons, and the Diablo Range, where Franciscan Complex or Silinian rocks are exposed.

  6. End-systolic stress-velocity relation and circumferential fiber velocity shortening for analysing left ventricular function in mice

    Energy Technology Data Exchange (ETDEWEB)

    Fayssoil, A. [Cardiologie, Hopital europeen Georges Pompidou, 20, rue le blanc, Paris (France)], E-mail: fayssoil2000@yahoo.fr; Renault, G. [CNRS UMR 8104, Inserm, U567, Institut Cochin, Universite Paris Descartes, Paris (France); Fougerousse, F. [Genethon, RD, Evry (France)

    2009-08-15

    Traditionally, analysing left ventricular (LV) performance relies on echocardiography by evaluating shortening fraction (SF) in mice. SF is influenced by load conditions. End-systolic stress-velocity (ESSV) relation and circumferential fiber velocity (VcF) shortening are more relevant parameters for evaluating systolic function regardless load conditions particularly in mice's models of heart failure.

  7. Determination of viscosity through terminal velocity: use of the drag force with a quadratic term in velocity

    DEFF Research Database (Denmark)

    Vertchenko, Lev; Vertchenko, Larissa

    2017-01-01

    A correction to the term with quadratic dependency of the velocity in the Oseen´s drag force by a dimensionless factor is proposed in order to determine the viscosity of glycerin through the measurement of the terminal velocity of spheres falling inside the fluid. This factor incorporates the eff...

  8. Velocity Tracking Control of Wheeled Mobile Robots by Iterative Learning Control

    Directory of Open Access Journals (Sweden)

    Xiaochun Lu

    2016-05-01

    Full Text Available This paper presents an iterative learning control (ILC strategy to resolve the trajectory tracking problem of wheeled mobile robots (WMRs based on dynamic model. In the previous study of WMRs’ trajectory tracking, ILC was usually applied to the kinematical model of WMRs with the assumption that desired velocity can be tracked immediately. However, this assumption cannot be realized in the real world at all. The kinematic and dynamic models of WMRs are deduced in this chapter, and a novel combination of D-type ILC algorithm and dynamic model of WMR with random bounded disturbances are presented. To analyze the convergence of the algorithm, the method of contracting mapping, which shows that the designed controller can make the velocity tracking errors converge to zero completely when the iteration times tend to infinite, is adopted. Simulation results show the effectiveness of D-type ILC in the trajectory tracking problem of WMRs, demonstrating the effectiveness and robustness of the algorithm in the condition of random bounded disturbance. A comparative study conducted between D-type ILC and compound cosine function neural network (NN controller also demonstrates the effectiveness of the ILC strategy.

  9. Attenuation and velocity dispersion in the exploration seismic frequency band

    Science.gov (United States)

    Sun, Langqiu

    In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

  10. Spatially-resolved velocities of thermally-produced spray droplets using a velocity-divided Abel inversion of photographed streaks

    Science.gov (United States)

    Kawaguchi, Y.; Kobayashi, N.; Yamagata, Y.; Miyazaki, F.; Yamasaki, M.; Muraoka, K.

    2017-10-01

    Droplet velocities of thermal spray are known to have profound effects on important coating qualities, such as adhesive strength, porosity, and hardness, for various applications. For obtaining the droplet velocities, therefore, the TOF (time-of-flight) technique has been widely used, which relies on observations of emitted radiation from the droplets, where all droplets along the line-of-sight contribute to signals. Because droplets at and near the flow axis mostly contribute coating layers, it has been hoped to get spatially resolved velocities. For this purpose, a velocity-divided Abel inversion was devised from CMOS photographic data. From this result, it has turned out that the central velocity is about 25% higher than that obtained from the TOF technique for the case studied (at the position 150 mm downstream of the plasma spray gun, where substrates for spray coatings are usually placed). Further implications of the obtained results are discussed.

  11. Validity of a Commercial Linear Encoder to Estimate Bench Press 1 RM from the Force-Velocity Relationship

    Science.gov (United States)

    Bosquet, Laurent; Porta-Benache, Jeremy; Blais, Jérôme

    2010-01-01

    The aim of this study was to assess the validity and accuracy of a commercial linear encoder (Musclelab, Ergotest, Norway) to estimate Bench press 1 repetition maximum (1RM) from the force - velocity relationship. Twenty seven physical education students and teachers (5 women and 22 men) with a heterogeneous history of strength training participated in this study. They performed a 1 RM test and a force - velocity test using a Bench press lifting task in a random order. Mean 1 RM was 61.8 ± 15.3 kg (range: 34 to 100 kg), while 1 RM estimated by the Musclelab’s software from the force-velocity relationship was 56.4 ± 14.0 kg (range: 33 to 91 kg). Actual and estimated 1 RM were very highly correlated (r = 0.93, p<0.001) but largely different (Bias: 5.4 ± 5.7 kg, p < 0.001, ES = 1.37). The 95% limits of agreement were ±11.2 kg, which represented ±18% of actual 1 RM. It was concluded that 1 RM estimated from the force-velocity relationship was a good measure for monitoring training induced adaptations, but also that it was not accurate enough to prescribe training intensities. Additional studies are required to determine whether accuracy is affected by age, sex or initial level. Key points Some commercial devices allow to estimate 1 RM from the force-velocity relationship. These estimations are valid. However, their accuracy is not high enough to be of practical help for training intensity prescription. Day-to-day reliability of force and velocity measured by the linear encoder has been shown to be very high, but the specific reliability of 1 RM estimated from the force-velocity relationship has to be determined before concluding to the usefulness of this approach in the monitoring of training induced adaptations. PMID:24149641

  12. Maximal intended velocity training induces greater gains in bench press performance than deliberately slower half-velocity training.

    Science.gov (United States)

    González-Badillo, Juan José; Rodríguez-Rosell, David; Sánchez-Medina, Luis; Gorostiaga, Esteban M; Pareja-Blanco, Fernando

    2014-01-01

    The purpose of this study was to compare the effect on strength gains of two isoinertial resistance training (RT) programmes that only differed in actual concentric velocity: maximal (MaxV) vs. half-maximal (HalfV) velocity. Twenty participants were assigned to a MaxV (n = 9) or HalfV (n = 11) group and trained 3 times per week during 6 weeks using the bench press (BP). Repetition velocity was controlled using a linear velocity transducer. A complementary study (n = 10) aimed to analyse whether the acute metabolic (blood lactate and ammonia) and mechanical response (velocity loss) was different between the MaxV and HalfV protocols used. Both groups improved strength performance from pre- to post-training, but MaxV resulted in significantly greater gains than HalfV in all variables analysed: one-repetition maximum (1RM) strength (18.2 vs. 9.7%), velocity developed against all (20.8 vs. 10.0%), light (11.5 vs. 4.5%) and heavy (36.2 vs. 17.3%) loads common to pre- and post-tests. Light and heavy loads were identified with those moved faster or slower than 0.80 m · s(-1) (∼ 60% 1RM in BP). Lactate tended to be significantly higher for MaxV vs. HalfV, with no differences observed for ammonia which was within resting values. Both groups obtained the greatest improvements at the training velocities (≤ 0.80 m · s(-1)). Movement velocity can be considered a fundamental component of RT intensity, since, for a given %1RM, the velocity at which loads are lifted largely determines the resulting training effect. BP strength gains can be maximised when repetitions are performed at maximal intended velocity.

  13. Generation of the auroral electron velocity distribution by stochastic acceleration

    International Nuclear Information System (INIS)

    Bryant, D.A.; Cook, A.C.; Wang, Z.-S.; Angelis, U. de.

    1990-07-01

    In a further development of the wave theory of the aurora, it is demonstrated, using a Monte-Carlo numerical model, that the characteristic peak in the auroral electron velocity distribution can be generated stochastically through resonant interactions between an initially monotonic distribution and lower-hybrid electrostatic turbulence. The principal requirement is that the velocity spectrum of resonant waves has a sharp cut-off at high velocity. It is then shown that a cut-off is expected as a natural consequence of the difference between the phase and group velocities of lower-hybrid waves. The possibility is considered that a second peak, sometimes observed at lower velocities, is due to the same statistical mechanism, arising from the damping of waves of low phase velocity. An enhancement of wave intensity is found at higher velocities, where momentum flows preferentially from electrons to waves. The relation between the wave theory and the currently prevailing potential-difference theory emerges clearly from the analysis. (author)

  14. Blood flow velocity in migraine attacks - a transcranial Doppler study

    International Nuclear Information System (INIS)

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D.

    1991-01-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs

  15. VELOCITY VARIATIONS IN THE PHOENIX–HERMUS STAR STREAM

    Energy Technology Data Exchange (ETDEWEB)

    Carlberg, R. G. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Grillmair, C. J., E-mail: carlberg@astro.utoronto.ca, E-mail: carl@ipac.caltech.edu [Spitzer Science Center, 1200 E. California Blvd., Pasadena, CA 91125 (United States)

    2016-10-20

    Measurements of velocity and density perturbations along stellar streams in the Milky Way provide a time-integrated measure of dark matter substructure at larger galactic radius than the complementary instantaneous inner-halo strong lensing detection of dark matter sub-halos in distant galaxies. An interesting case to consider is the proposed Phoenix–Hermus star stream, which is long, thin, and on a nearly circular orbit, making it a particular good target to study for velocity variations along its length. In the presence of dark matter sub-halos, the stream velocities are significantly perturbed in a manner that is readily understood with the impulse approximation. A set of simulations shows that only sub-halos above a few 10{sup 7} M {sub ⊙} lead to reasonably long-lived observationally detectable velocity variations of amplitude of order 1 km s{sup −1}, with an average of about one visible hit per (two-armed) stream over a 3 Gyr interval. An implication is that globular clusters themselves will not have a visible impact on the stream. Radial velocities have the benefit of being completely insensitive to distance errors. Distance errors scatter individual star velocities perpendicular and tangential to the mean orbit, but their mean values remain unbiased. Calculations like these help build the quantitative case to acquire large, fairly deep, precision velocity samples of stream stars.

  16. Measurement of sound velocity profiles in fluids for process monitoring

    International Nuclear Information System (INIS)

    Wolf, M; Kühnicke, E; Lenz, M; Bock, M

    2012-01-01

    In ultrasonic measurements, the time of flight to the object interface is often the only information that is analysed. Conventionally it is only possible to determine distances or sound velocities if the other value is known. The current paper deals with a novel method to measure the sound propagation path length and the sound velocity in media with moving scattering particles simultaneously. Since the focal position also depends on sound velocity, it can be used as a second parameter. Via calibration curves it is possible to determine the focal position and sound velocity from the measured time of flight to the focus, which is correlated to the maximum of averaged echo signal amplitude. To move focal position along the acoustic axis, an annular array is used. This allows measuring sound velocity locally resolved without any previous knowledge of the acoustic media and without a reference reflector. In previous publications the functional efficiency of this method was shown for media with constant velocities. In this work the accuracy of these measurements is improved. Furthermore first measurements and simulations are introduced for non-homogeneous media. Therefore an experimental set-up was created to generate a linear temperature gradient, which also causes a gradient of sound velocity.

  17. Estimation of sand dune thickness using a vertical velocity profile

    International Nuclear Information System (INIS)

    Al-Shuhail, Abdullatif A.

    2004-01-01

    Previous field and mathematical studies have shown that sand dunes may have vertical velocity profiles (i.e. continuous increase of velocity with depth). Therefore, computing the dunes thickness using conventional seismic refraction methods that assume a vertically homogeneous layer will likely produce some errors. The purpose of this study is to quantify the effect of the vertical velocity profile in a sand dune on the process of thickness estimation using seismic refraction data. First, the time distance (T-X) data of the direct wave in the dune is calculated using a vertical velocity profile, V (z), derived from Hertz-Mindlin contact theory. Then the thickness is estimated from the calculated T-X data, intercept time and velocity of the refractor at the dune's base assuming a constant velocity in the dune. The error in the estimated thickness due to the constant-velocity assumption increases with increasing thickness and decreasing porosity of the dune. For sand dunes with porosities greater than 0.2 and thickness less than 200 meter, the error is less than 15%. (author)

  18. Burning velocity measurements of nitrogen-containing compounds.

    Science.gov (United States)

    Takizawa, Kenji; Takahashi, Akifumi; Tokuhashi, Kazuaki; Kondo, Shigeo; Sekiya, Akira

    2008-06-30

    Burning velocity measurements of nitrogen-containing compounds, i.e., ammonia (NH3), methylamine (CH3NH2), ethylamine (C2H5NH2), and propylamine (C3H7NH2), were carried out to assess the flammability of potential natural refrigerants. The spherical-vessel (SV) method was used to measure the burning velocity over a wide range of sample and air concentrations. In addition, flame propagation was directly observed by the schlieren photography method, which showed that the spherical flame model was applicable to flames with a burning velocity higher than approximately 5 cm s(-1). For CH3NH2, the nozzle burner method was also used to confirm the validity of the results obtained by closed vessel methods. We obtained maximum burning velocities (Su0,max) of 7.2, 24.7, 26.9, and 28.3 cm s(-1) for NH3, CH3NH2, C2H5NH2, and C3H7NH2, respectively. It was noted that the burning velocities of NH3 and CH3NH2 were as high as those of the typical hydrofluorocarbon refrigerants difluoromethane (HFC-32, Su0,max=6.7 cm s(-1)) and 1,1-difluoroethane (HFC-152a, Su0,max=23.6 cm s(-1)), respectively. The burning velocities were compared with those of the parent alkanes, and it was found that introducing an NH2 group into hydrocarbon molecules decreases their burning velocity.

  19. Amphibious Shear Velocity Structure of the Cascadia Subduction Zone

    Science.gov (United States)

    Janiszewski, H. A.; Gaherty, J. B.; Abers, G. A.; Gao, H.

    2017-12-01

    The amphibious Cascadia Initiative crosses the coastline of the Cascadia subduction zone (CSZ) deploying seismometers from the Juan de Fuca ridge offshore to beyond the volcanic arc onshore. This allows unprecedented seismic imaging of the CSZ, enabling examination of both the evolution of the Juan de Fuca plate prior to and during subduction as well as the along strike variability of the subduction system. Here we present new results from an amphibious shear velocity model for the crust and upper mantle across the Cascadia subduction zone. The primary data used in this inversion are surface-wave phase velocities derived from ambient-noise Rayleigh-wave data in the 10 - 20 s period band, and teleseismic earthquake Rayleigh wave phase velocities in the 20 - 160 s period band. Phase velocity maps from these data reflect major tectonic structures including the transition from oceanic to continental lithosphere, Juan de Fuca lithosphere that is faster than observations in the Pacific for oceanic crust of its age, slow velocities associated with the accretionary prism, the front of the fast subducting slab, and the Cascades volcanic arc which is associated with slower velocities in the south than in the north. Crustal structures are constrained by receiver functions in the offshore forearc and onshore regions, and by active source constraints on the Juan de Fuca plate prior to subduction. The shear-wave velocities are interpreted in their relationships to temperature, presence of melt or hydrous alteration, and compositional variation of the CSZ.

  20. Seismic Tomography and the Development of a State Velocity Profile

    Science.gov (United States)

    Marsh, S. J.; Nakata, N.

    2017-12-01

    Earthquakes have been a growing concern in the State of Oklahoma in the last few years and as a result, accurate earthquake location is of utmost importance. This means using a high resolution velocity model with both lateral and vertical variations. Velocity data is determined using ambient noise seismic interferometry and tomography. Passive seismic data was acquired from multiple IRIS networks over the span of eight years (2009-2016) and filtered for earthquake removal to obtain the background ambient noise profile for the state. Seismic Interferometry is applied to simulate ray paths between stations, this is done with each possible station pair for highest resolution. Finally the method of seismic tomography is used to extract the velocity data and develop the state velocity map. The final velocity profile will be a compilation of different network analyses due to changing station availability from year to year. North-Central Oklahoma has a dense seismic network and has been operating for the past few years. The seismic stations are located here because this is the most seismically active region. Other parts of the state have not had consistent coverage from year to year, and as such a reliable and high resolution velocity profile cannot be determined from this network. However, the Transportable Array (TA) passed through Oklahoma in 2014 and provided a much wider and evenly spaced coverage. The goal of this study is to ultimately combine these two arrays over time, and provide a high quality velocity profile for the State of Oklahoma.

  1. Liquid velocity in upward and downward air-water flows

    International Nuclear Information System (INIS)

    Sun Xiaodong; Paranjape, Sidharth; Kim, Seungjin; Ozar, Basar; Ishii, Mamoru

    2004-01-01

    Local characteristics of the liquid phase in upward and downward air-water two-phase flows were experimentally investigated in a 50.8-mm inner-diameter round pipe. An integral laser Doppler anemometry (LDA) system was used to measure the axial liquid velocity and its fluctuations. No effect of the flow direction on the liquid velocity radial profile was observed in single-phase liquid benchmark experiments. Local multi-sensor conductivity probes were used to measure the radial profiles of the bubble velocity and the void fraction. The measurement results in the upward and downward two-phase flows are compared and discussed. The results in the downward flow demonstrated that the presence of the bubbles tended to flatten the liquid velocity radial profile, and the maximum liquid velocity could occur off the pipe centerline, in particular at relatively low flow rates. However, the maximum liquid velocity always occurred at the pipe center in the upward flow. Also, noticeable turbulence enhancement due to the bubbles in the two-phase flows was observed in the current experimental flow conditions. Furthermore, the distribution parameter and the void-weighted area-averaged drift velocity were obtained based on the definitions

  2. EVOLUTION OF ROTATIONAL VELOCITIES OF A-TYPE STARS

    International Nuclear Information System (INIS)

    Yang Wuming; Bi Shaolan; Tian Zhijia; Meng Xiangcun

    2013-01-01

    The equatorial velocity of A-type stars undergoes an acceleration in the first third of the main sequence (MS) stage, but the velocity decreases as if the stars were not undergoing any redistribution of angular momentum in the external layers in the last stage of the MS phase. Our calculations show that the acceleration and the decrease of the equatorial velocity can be reproduced by the evolution of the differential rotation zero-age MS model with the angular momentum transport caused by hydrodynamic instabilities during the MS stage. The acceleration results from the fact that the angular momentum stored in the interiors of the stars is transported outward. In the last stage, the core and the radiative envelope are uncoupling, and the rotation of the envelope is a quasi-solid rotation; the uncoupling and the expansion of the envelope indicate that the decrease of the equatorial velocity approximately follows the slope for the change in the equatorial velocity of the model without any redistribution of angular momentum. When the fractional age 0.3 ∼ MS ∼< 0.5, the equatorial velocity remains almost constant for stars whose central density increases with age in the early stage of the MS phase, while the velocity decreases with age for stars whose central density decreases with age in the early stage of the MS phase.

  3. Blood flow velocity in migraine attacks - a transcranial Doppler study

    Energy Technology Data Exchange (ETDEWEB)

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D. (Rijksuniversiteit Leiden (Netherlands))

    1991-05-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs.

  4. Streaming Velocities and the Baryon Acoustic Oscillation Scale.

    Science.gov (United States)

    Blazek, Jonathan A; McEwen, Joseph E; Hirata, Christopher M

    2016-03-25

    At the epoch of decoupling, cosmic baryons had supersonic velocities relative to the dark matter that were coherent on large scales. These velocities subsequently slow the growth of small-scale structure and, via feedback processes, can influence the formation of larger galaxies. We examine the effect of streaming velocities on the galaxy correlation function, including all leading-order contributions for the first time. We find that the impact on the baryon acoustic oscillation (BAO) peak is dramatically enhanced (by a factor of ∼5) over the results of previous investigations, with the primary new effect due to advection: if a galaxy retains memory of the primordial streaming velocity, it does so at its Lagrangian, rather than Eulerian, position. Since correlations in the streaming velocity change rapidly at the BAO scale, this advection term can cause a significant shift in the observed BAO position. If streaming velocities impact tracer density at the 1% level, compared to the linear bias, the recovered BAO scale is shifted by approximately 0.5%. This new effect, which is required to preserve Galilean invariance, greatly increases the importance of including streaming velocities in the analysis of upcoming BAO measurements and opens a new window to the astrophysics of galaxy formation.

  5. On a randomly imperfect spherical cap pressurized by a random ...

    African Journals Online (AJOL)

    On a randomly imperfect spherical cap pressurized by a random dynamic load. ... In this paper, we investigate a dynamical system in a random setting of dual ... characterization of the random process for determining the dynamic buckling load ...

  6. Anomalous scaling of a passive vector advected by the Navier-Stokes velocity field

    International Nuclear Information System (INIS)

    Jurcisinova, E; Jurcisin, M; Remecky, R

    2009-01-01

    Using the field theoretic renormalization group and the operator-product expansion, the model of a passive vector field (a weak magnetic field in the framework of the kinematic MHD) advected by the velocity field which is governed by the stochastic Navier-Stokes equation with the Gaussian random stirring force δ-correlated in time and with the correlator proportional to k 4-d-2ε is investigated to the first order in ε (one-loop approximation). It is shown that the single-time correlation functions of the advected vector field have anomalous scaling behavior and the corresponding exponents are calculated in the isotropic case, as well as in the case with the presence of large-scale anisotropy. The hierarchy of the anisotropic critical dimensions is briefly discussed and the persistence of the anisotropy inside the inertial range is demonstrated on the behavior of the skewness and hyperskewness (dimensionless ratios of correlation functions) as functions of the Reynolds number Re. It is shown that even though the present model of a passive vector field advected by the realistic velocity field is mathematically more complicated than, on one hand, the corresponding models of a passive vector field advected by 'synthetic' Gaussian velocity fields and, on the other hand, than the corresponding model of a passive scalar quantity advected by the velocity field driven by the stochastic Navier-Stokes equation, the final one-loop approximate asymptotic scaling behavior of the single-time correlation or structure functions of the advected fields of all models are defined by the same anomalous dimensions (up to normalization)

  7. EFFECTS OF A 6-WEEK JUNIOR TENNIS CONDITIONING PROGRAM ON SERVICE VELOCITY

    Directory of Open Access Journals (Sweden)

    Jaime Fernandez-Fernandez

    2013-06-01

    Full Text Available This study examined the effects of a 6-week strength-training program on serve velocity in youth tennis players. Thirty competitive healthy and nationally ranked male junior tennis players (13 years of age were randomly and equally divided into control and training groups. The training group performed 3 sessions (60-70 min weekly for 6 weeks, comprising core strength, elastic resistance and medicine ball exercises. Both groups (control and training also performed a supervised stretching routine at the end of each training session, during the 6 week intervention. Service velocity, service accuracy and shoulder internal/external rotation were assessed initially and at the end of the 6-week conditioning program for both, control and training groups. There was a significant improvement in the serve velocity for the training group (p = 0. 0001 after the intervention, whereas in the control group there were no differences between pre and post-tests (p = 0.29. Serve accuracy was not affected in the training group (p = 0.10, nor in the control group (p = 0.15. Shoulder internal/external rotation ROM significantly improved in both groups, training (p = 0.001 and control (p = 0.0001. The present results showed that a short- term training program for young tennis players, using minimum equipment and effort, can result in improved tennis performance (i.e., serve velocity and a reduction in the risk of a possible overuse injury, reflected by an improvement in shoulder external/internal range of motion

  8. The influence of gas phase velocity fluctuations on primary atomization and droplet deformation

    Science.gov (United States)

    Kourmatzis, A.; Masri, A. R.

    2014-02-01

    The effects of grid-generated velocity fluctuations on the primary atomization and subsequent droplet deformation of a range of laminar liquid jets are examined using microscopic high-speed backlit imaging of the break-up zone and laser Doppler anemometry of the gas phase separately. This is done for fixed gas mean flow conditions in a miniature wind tunnel experiment utilizing a selection of fuels, turbulence-generating grids and two syringe sizes. The constant mean flow allows for an isolated study of velocity fluctuation effects on primary atomization in a close approximation to homogeneous decaying turbulence. The qualitative morphology of the primary break-up region is examined over a range of turbulence intensities, and spectral analysis is performed in order to ascertain the break-up frequency which, for a case of no grid, compares well with the existing literature. The addition of velocity fluctuations tends to randomize the break-up process. Slightly downstream of the break-up region, image processing is conducted in order to extract a number of metrics, which do not depend on droplet sphericity, and these include droplet aspect ratio and orientation, the latter quantity being somewhat unconventional in spray characterization. A turbulent Weber number which takes into account gas phase fluctuations is utilized to characterize the resulting droplet shapes, in addition to a mean Weber number . Above a a clear positive relationship exists between the mean aspect ratio of droplets and the turbulent Weber number where is varied by altering all relevant variables including the velocity root mean square, the initial droplet diameter, the surface tension and the density.

  9. Critique of the use of deposition velocity in modeling indoor air quality

    International Nuclear Information System (INIS)

    Nazaroff, W.W.; Weschler, C.J.

    1993-01-01

    Among the potential fates of indoor air pollutants are a variety of physical and chemical interactions with indoor surfaces. In deterministic mathematical models of indoor air quality, these interactions are usually represented as a first-order loss process, with the loss rate coefficient given as the product of the surface-to-volume ratio of the room times a deposition velocity. In this paper, the validity of this representation of surface-loss mechanisms is critically evaluated. From a theoretical perspective, the idea of a deposition velocity is consistent with the following representation of an indoor air environment. Pollutants are well-mixed throughout a core region which is separated from room surfaces by boundary layers. Pollutants migrate through the boundary layers by a combination of diffusion (random motion resulting from collisions with surrounding gas molecules), advection (transport by net motion of the fluid), and, in some cases, other transport mechanisms. The rate of pollutant loss to a surface is governed by a combination of the rate of transport through the boundary layer and the rate of reaction at the surface. The deposition velocity expresses the pollutant flux density (mass or moles deposited per area per time) to the surface divided by the pollutant concentration in the core region. This concept has substantial value to the extent that the flux density is proportional to core concentration. Published results from experimental and modeling studies of fine particles, radon decay products, ozone, and nitrogen oxides are used as illustrations of both the strengths and weaknesses of deposition velocity as a parameter to indicate the rate of indoor air pollutant loss on surfaces. 66 refs., 5 tabs

  10. CHARACTERIZING THE GALACTIC WHITE DWARF BINARY POPULATION WITH SPARSELY SAMPLED RADIAL VELOCITY DATA

    International Nuclear Information System (INIS)

    Maoz, Dan; Badenes, Carles; Bickerton, Steven J.

    2012-01-01

    We present a method to characterize statistically the parameters of a detached binary sample—binary fraction, separation distribution, and mass-ratio distribution—using noisy radial velocity data with as few as two, randomly spaced, epochs per object. To do this, we analyze the distribution of ΔRV max , the maximum radial velocity difference between any two epochs for the same object. At low values, the core of this distribution is dominated by measurement errors, but for large enough samples there is a high-velocity tail that can effectively constrain the parameters of the binary population. We discuss our approach for the case of a population of detached white dwarf (WD) binaries with separations that are decaying via gravitational wave emission. We derive analytic expressions for the present-day distribution of separations, integrated over the star formation history of the Galaxy, for parameterized initial WD separation distributions at the end of the common-envelope phase. We use Monte Carlo techniques to produce grids of simulated ΔRV max distributions with specific binary population parameters, and the same sampling cadences and radial velocity errors as the observations, and we compare them to the real ΔRV max distribution to constrain the properties of the binary population. We illustrate the sensitivity of the method to both the model and observational parameters. In the particular case of binary WDs, every model population predicts a merger rate per star which can easily be compared to specific Type Ia supernova rates. In a companion paper, we apply the method to a sample of ∼4000 WDs from the Sloan Digital Sky Survey. The binary fractions and separation distribution parameters allowed by the data indicate a rate of WD-WD mergers per unit stellar mass in the Galactic disk, ∼1 × 10 –13 mergers yr –1 M –1 ☉ , remarkably similar to the rate per unit mass of Type Ia supernovae in Milky Way like galaxies.

  11. Uncertainty estimation of the velocity model for stations of the TrigNet GPS network

    Science.gov (United States)

    Hackl, M.; Malservisi, R.; Hugentobler, U.

    2010-12-01

    Satellite based geodetic techniques - above all GPS - provide an outstanding tool to measure crustal motions. They are widely used to derive geodetic velocity models that are applied in geodynamics to determine rotations of tectonic blocks, to localize active geological features, and to estimate rheological properties of the crust and the underlying asthenosphere. However, it is not a trivial task to derive GPS velocities and their uncertainties from positioning time series. In general time series are assumed to be represented by linear models (sometimes offsets, annual, and semi-annual signals are included) and noise. It has been shown that error models accounting only for white noise tend to underestimate the uncertainties of rates derived from long time series and that different colored noise components (flicker noise, random walk, etc.) need to be considered. However, a thorough error analysis including power spectra analyses and maximum likelihood estimates is computationally expensive and is usually not carried out for every site, but the uncertainties are scaled by latitude dependent factors. Analyses of the South Africa continuous GPS network TrigNet indicate that the scaled uncertainties overestimate the velocity errors. So we applied a method similar to the Allan Variance that is commonly used in the estimation of clock uncertainties and is able to account for time dependent probability density functions (colored noise) to the TrigNet time series. Comparisons with synthetic data show that the noise can be represented quite well by a power law model in combination with a seasonal signal in agreement with previous studies, which allows for a reliable estimation of the velocity error. Finally, we compared these estimates to the results obtained by spectral analyses using CATS. Small differences may originate from non-normal distribution of the noise.

  12. Blocked Randomization with Randomly Selected Block Sizes

    Directory of Open Access Journals (Sweden)

    Jimmy Efird

    2010-12-01

    Full Text Available When planning a randomized clinical trial, careful consideration must be given to how participants are selected for various arms of a study. Selection and accidental bias may occur when participants are not assigned to study groups with equal probability. A simple random allocation scheme is a process by which each participant has equal likelihood of being assigned to treatment versus referent groups. However, by chance an unequal number of individuals may be assigned to each arm of the study and thus decrease the power to detect statistically significant differences between groups. Block randomization is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. Yet still, the allocation process may be predictable, for example, when the investigator is not blind and the block size is fixed. This paper provides an overview of blocked randomization and illustrates how to avoid selection bias by using random block sizes.

  13. Development of an optical fiber flow velocity sensor.

    Science.gov (United States)

    Harada, Toshio; Kamoto, Kenji; Abe, Kyutaro; Izumo, Masaki

    2009-01-01

    A new optical fiber flow velocity sensor was developed by using an optical fiber information network system in sewer drainage pipes. The optical fiber flow velocity sensor operates without electric power, and the signals from the sensor can be transmitted over a long distance through the telecommunication system in the optical fiber network. Field tests were conducted to check the performance of the sensor in conduits in the pumping station and sewage pond managed by the Tokyo Metropolitan Government. Test results confirmed that the velocity sensor can be used for more than six months without any trouble even in sewer drainage pipes.

  14. Coding of Velocity Storage in the Vestibular Nuclei

    Directory of Open Access Journals (Sweden)

    Sergei B. Yakushin

    2017-08-01

    Full Text Available Semicircular canal afferents sense angular acceleration and output angular velocity with a short time constant of ≈4.5 s. This output is prolonged by a central integrative network, velocity storage that lengthens the time constants of eye velocity. This mechanism utilizes canal, otolith, and visual (optokinetic information to align the axis of eye velocity toward the spatial vertical when head orientation is off-vertical axis. Previous studies indicated that vestibular-only (VO and vestibular-pause-saccade (VPS neurons located in the medial and superior vestibular nucleus could code all aspects of velocity storage. A recently developed technique enabled prolonged recording while animals were rotated and received optokinetic stimulation about a spatial vertical axis while upright, side-down, prone, and supine. Firing rates of 33 VO and 8 VPS neurons were studied in alert cynomolgus monkeys. Majority VO neurons were closely correlated with the horizontal component of velocity storage in head coordinates, regardless of head orientation in space. Approximately, half of all tested neurons (46% code horizontal component of velocity in head coordinates, while the other half (54% changed their firing rates as the head was oriented relative to the spatial vertical, coding the horizontal component of eye velocity in spatial coordinates. Some VO neurons only coded the cross-coupled pitch or roll components that move the axis of eye rotation toward the spatial vertical. Sixty-five percent of these VO and VPS neurons were more sensitive to rotation in one direction (predominantly contralateral, providing directional orientation for the subset of VO neurons on either side of the brainstem. This indicates that the three-dimensional velocity storage integrator is composed of directional subsets of neurons that are likely to be the bases for the spatial characteristics of velocity storage. Most VPS neurons ceased firing during drowsiness, but the firing

  15. Time-dependent coolant velocity measurements in an operating BWR

    International Nuclear Information System (INIS)

    Luebbesmeyer, D.; Crowe, R.D.

    1980-01-01

    A method to measure time-dependent fluid velocities in BWR-bundle elements by noise analysis of the incore-neutron-detector signals is shown. Two application examples of the new method are given. The time behaviour of the fluid velocity in the bundle element during a scheduled power excursion of the plant. The change of power was performed by changing the coolant flow through the core The apparent change of the fluid velocity due to thermal elongation of the helix-drive of the TIP-system. A simplified mathematical model was derived for this elongation to use as a reference to check the validity of the new method. (author)

  16. Lower bound on the electroweak wall velocity from hydrodynamic instability

    Energy Technology Data Exchange (ETDEWEB)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D., E-mail: megevand@mdp.edu.ar, E-mail: membiela@mdp.edu.ar, E-mail: sanchez@mdp.edu.ar [IFIMAR (CONICET-UNMdP), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Deán Funes (7600) 3350 Mar del Plata (Argentina)

    2015-03-01

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis.

  17. Lower bound on the electroweak wall velocity from hydrodynamic instability

    International Nuclear Information System (INIS)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D.

    2015-01-01

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis

  18. Lower bound on the electroweak wall velocity from hydrodynamic instability

    Energy Technology Data Exchange (ETDEWEB)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D. [IFIMAR (CONICET-UNMdP), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Deán Funes (7600) 3350 Mar del Plata (Argentina)

    2015-03-27

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis.

  19. HIGH VELOCITY THERMAL GUN FOR SURFACE PREPARATION AND TREATMENT

    Directory of Open Access Journals (Sweden)

    I.A. Gorlach

    2012-01-01

    Full Text Available Many surface preparation and treatment processes utilise compressed air to propel particles against surfaces in order to clean and treat them. The effectiveness of the processes depends on the velocity of the particles, which in turn depends on the pressure of the compressed air. This paper describes a thermal gun built on the principles of High Velocity Air Fuel (HVAF and High Velocity Oxy Fuel (HVOF processes. The designed apparatus can be used for abrasive blasting, coating of surfaces, cutting of rocks, removing rubber from mining equipment, cleaning of contaminations etc.

  20. A Method of Initial Velocity Measurement for Rocket Projectile

    Directory of Open Access Journals (Sweden)

    Zhang Jiancheng

    2017-01-01

    Full Text Available In this paper, a novel method is proposed to measure the initial velocity of the rocket based on STFT (the short-time Fourier transform and the WT (wavelet transform. The radar echo signal processing procedure involves the following steps: sampling process, overlapping windows, wavelet decomposition and reconstruction, computing FFT (Fast Fourier Transform and spectrum analysis, power spectrum peak detection. Then, according to the peak of the detection power spectrum, the corresponding Doppler frequency is obtained. Finally, on the basis of the relationship between Doppler frequency and instantaneous velocity, the V-T curve is drawn in MATLAB to obtain the initial velocity of the rocket muzzle.

  1. 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.

  2. Drift velocity monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2010-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented.

  3. Numerical modeling of probe velocity effects for electromagnetic NDE methods

    Science.gov (United States)

    Shin, Y. K.; Lord, W.

    The present discussion of magnetic flux (MLF) leakage inspection introduces the behavior of motion-induced currents. The results obtained indicate that velocity effects exist at even low probe speeds for magnetic materials, compelling the inclusion of velocity effects in MLF testing of oil pipelines, where the excitation level and pig speed are much higher than those used in the present work. Probe velocity effect studies should influence probe design, defining suitable probe speed limits and establishing training guidelines for defect-characterization schemes.

  4. Using the load-velocity relationship for 1RM prediction.

    OpenAIRE

    Jidovtseff, Boris; Harris, N. K.; Crielaard, Jean-Michel; Cronin, J. B.

    2011-01-01

    Jidovtseff, B, Harris, NK, Crielaard, J-M, and Cronin, JB. Using the load-velocity relationship for 1RM prediction. J Strength Cond Res 24(x): 000-000, 2009-The purpose of this study was to investigate the ability of the load-velocity relationship to accurately predict a bench press 1 repetition maximum (1RM). Data from 3 different bench press studies (n = 112) that incorporated both 1RM assessment and submaximal load-velocity profiling were analyzed. Individual regression analysis was perfor...

  5. Measurement of unsteady airflow velocity at nozzle outlet

    Science.gov (United States)

    Pyszko, René; Machů, Mário

    2017-09-01

    The paper deals with a method of measuring and evaluating the cooling air flow velocity at the outlet of the flat nozzle for cooling a rolled steel product. The selected properties of the Prandtl and Pitot sensing tubes were measured and compared. A Pitot tube was used for operational measurements of unsteady dynamic pressure of the air flowing from nozzles to abtain the flow velocity. The article also discusses the effects of air temperature, pressure and relative air humidity on air density, as well as the influence of dynamic pressure filtering on the error of averaged velocity.

  6. Continuous measurements of in-bore projectile velocity

    International Nuclear Information System (INIS)

    Asay, J.R.; Konrad, C.H.; Hall, C.A.; Shahinpoor, M.

    1989-01-01

    The application of velocity interferometry to the continuous measurement of in-bore projectile velocity in a small-bore three-stage railgun is described. These measurements are useful for determining projectile acceleration and for evaluating gun performance. The launcher employed in these studies consists of a two-stage light gas gun used to inject projectiles into a railgun for additional acceleration. Results obtained for projectile velocities to 7.4 km/s with the two-stage injector are reported and potential improvements for railgun applications are discussed

  7. The velocity field induced by a helical vortex tube

    DEFF Research Database (Denmark)

    Fukumoto, Y.; Okulov, Valery

    2005-01-01

    The influence of finite-core thickness on the velocity field around a vortex tube is addressed. An asymptotic expansion of the Biot-Savart law is made to a higher order in a small parameter, the ratio of core radius to curvature radius, which consists of the velocity field due to lines of monopoles...... and dipoles arranged on the centerline of the tube. The former is associated with an infinitely thin core and is featured by the circulation alone. The distribution of vorticity in the core reflects on the strength of dipole. This result is applied to a helical vortex tube, and the induced velocity due...

  8. Variational multi-valued velocity field estimation for transparent sequences

    DEFF Research Database (Denmark)

    Ramírez-Manzanares, Alonso; Rivera, Mariano; Kornprobst, Pierre

    2011-01-01

    Motion estimation in sequences with transparencies is an important problem in robotics and medical imaging applications. In this work we propose a variational approach for estimating multi-valued velocity fields in transparent sequences. Starting from existing local motion estimators, we derive...... a variational model for integrating in space and time such a local information in order to obtain a robust estimation of the multi-valued velocity field. With this approach, we can indeed estimate multi-valued velocity fields which are not necessarily piecewise constant on a layer –each layer can evolve...

  9. Analysis of velocity planning interpolation algorithm based on NURBS curve

    Science.gov (United States)

    Zhang, Wanjun; Gao, Shanping; Cheng, Xiyan; Zhang, Feng

    2017-04-01

    To reduce interpolation time and Max interpolation error in NURBS (Non-Uniform Rational B-Spline) inter-polation caused by planning Velocity. This paper proposed a velocity planning interpolation algorithm based on NURBS curve. Firstly, the second-order Taylor expansion is applied on the numerator in NURBS curve representation with parameter curve. Then, velocity planning interpolation algorithm can meet with NURBS curve interpolation. Finally, simulation results show that the proposed NURBS curve interpolator meet the high-speed and high-accuracy interpolation requirements of CNC systems. The interpolation of NURBS curve should be finished.

  10. A mixing method for traceable air velocity measurements

    International Nuclear Information System (INIS)

    Sillanpää, S; Heinonen, M

    2008-01-01

    A novel and quite simple method to establish a traceability link between air velocity and the national standards of mass and time is presented in this paper. The method is based on the humidification of flowing air before the blower of a wind tunnel with a known mass flow of water. Then air velocity can be calculated as a function of humidification water flow. The method is compared against a Pitot-tube-based velocity measurement in a wind tunnel at the MIKES. The results of these two different methods agreed well, with a maximum difference of 0.7%

  11. An interferometric velocity calibrator for 73Ge Moessbauer spectrometer

    International Nuclear Information System (INIS)

    Chow, L.; Kimble, T.

    1987-01-01

    A velocity calibrator based on a laser driven Michelson interferometer was designed for a 73 Ge Moessbauer spectrometer in the range of 100 to 500 μm/sec. The conventional method of counting the interference fringes cannot be used in this case because the displacement only spans about 3 to 15 μm and only a few fringes can be observed during one velocity sweep. The velocity calibration obtained this way was compared with the calibration obtained from 57 Fe measurement, and excellent agreement was found between the two methods. (orig.)

  12. Phased-array vector velocity estimation using transverse oscillations

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Marcher, Jønne; Jensen, Jørgen Arendt

    2012-01-01

    .79 to 0.92, indicating a correlation between the performance metrics of the TO spectrum and the velocity estimates. Because these performance metrics are much more readily computed, the TO fields can be optimized faster for improved velocity estimation of both simulations and measurements. For simulations......, but with a poorer performance compared with a 128-element transducer. The simulation and experimental results demonstrate that the TO method is suitable for use in conjunction with a phased-array transducer, and that 2-D vector velocity estimation is possible down to a depth of 15 cm....

  13. Field Testing of an In-well Point Velocity Probe for the Rapid Characterization of Groundwater Velocity

    Science.gov (United States)

    Osorno, T.; Devlin, J. F.

    2017-12-01

    Reliable estimates of groundwater velocity is essential in order to best implement in-situ monitoring and remediation technologies. The In-well Point Velocity Probe (IWPVP) is an inexpensive, reusable tool developed for rapid measurement of groundwater velocity at the centimeter-scale in monitoring wells. IWPVP measurements of groundwater speed are based on a small-scale tracer test conducted as ambient groundwater passes through the well screen and the body of the probe. Horizontal flow direction can be determined from the difference in tracer mass passing detectors placed in four funnel-and-channel pathways through the probe, arranged in a cross pattern. The design viability of the IWPVP was confirmed using a two-dimensional numerical model in Comsol Multiphysics, followed by a series of laboratory tank experiments in which IWPVP measurements were calibrated to quantify seepage velocities in both fine and medium sand. Lab results showed that the IWPVP was capable of measuring the seepage velocity in less than 20 minutes per test, when the seepage velocity was in the range of 0.5 to 4.0 m/d. Further, the IWPVP estimated the groundwater speed with a precision of ± 7%, and an accuracy of ± 14%, on average. The horizontal flow direction was determined with an accuracy of ± 15°, on average. Recently, a pilot field test of the IWPVP was conducted in the Borden aquifer, C.F.B. Borden, Ontario, Canada. A total of approximately 44 IWPVP tests were conducted within two 2-inch groundwater monitoring wells comprising a 5 ft. section of #8 commercial well screen. Again, all tests were completed in under 20 minutes. The velocities estimated from IWPVP data were compared to 21 Point Velocity Probe (PVP) tests, as well as Darcy-based estimates of groundwater velocity. Preliminary data analysis shows strong agreement between the IWPVP and PVP estimates of groundwater velocity. Further, both the IWPVP and PVP estimates of groundwater velocity appear to be reasonable when

  14. Magnetic field correlations in random flow with strong steady shear

    International Nuclear Information System (INIS)

    Kolokolov, I. V.; Lebedev, V. V.; Sizov, G. A.

    2011-01-01

    We analyze the magnetic kinematic dynamo in a conducting fluid where a stationary shear flow is accompanied by relatively weak random velocity fluctuations. The diffusionless and diffusion regimes are described. The growth rates of the magnetic field moments are related to the statistical characteristics of the flow describing divergence of the Lagrangian trajectories. The magnetic field correlation functions are examined, and their growth rates and scaling behavior are established. General assertions are illustrated by the explicit solution of a model where the velocity field is short-correlated in time.

  15. Bayesian inversion of surface wave data for discontinuities and velocity structure in the upper mantle using Neural Networks. Geologica Ultraiectina (287)

    NARCIS (Netherlands)

    Meier, U.

    2008-01-01

    We present a neural network approach to invert surface wave data for discontinuities and velocity structure in the upper mantle. We show how such a neural network can be trained on a set of random samples to give a continuous approximation to the inverse relation in a compact and computationally

  16. The role of topography and lateral velocity heterogeneities on near-source scattering and ground-motion variability

    KAUST Repository

    Imperatori, W.

    2015-07-28

    The scattering of seismic waves travelling in the Earth is not only caused by random velocity heterogeneity but also by surface topography. Both factors are known to strongly affect ground-motion complexity even at relatively short distance from the source. In this study, we simulate ground motion with a 3-D finite-difference wave propagation solver in the 0–5 Hz frequency band using three topography models representative of the Swiss alpine region and realistic heterogeneous media characterized by the Von Karman correlation functions. Subsequently, we analyse and quantify the characteristics of the scattered wavefield in the near-source region. Our study shows that both topography and velocity heterogeneity scattering may excite large coda waves of comparable relative amplitude, especially at around 1 Hz, although large variability in space may occur. Using the single scattering model, we estimate average QC values in the range 20–30 at 1 Hz, 36–54 at 1.5 Hz and 62–109 at 3 Hz for constant background velocity models with no intrinsic attenuation. In principle, envelopes of topography-scattered seismic waves can be qualitatively predicted by theoretical back-scattering models, while forward- or hybrid-scattering models better reproduce the effects of random velocity heterogeneity on the wavefield. This is because continuous multiple scattering caused by small-scale velocity perturbations leads to more gentle coda decay and envelope broadening, while topography abruptly scatters the wavefield once it impinges the free surface. The large impedance contrast also results in more efficient mode mixing. However, the introduction of realistic low-velocity layers near the free surface increases the complexity of ground motion dramatically and indicates that the role of topography in elastic waves scattering can be relevant especially in proximity of the source. Long-period surface waves can form most of the late coda, especially when intrinsic attenuation is taken

  17. Random walks, random fields, and disordered systems

    CERN Document Server

    Černý, Jiří; Kotecký, Roman

    2015-01-01

    Focusing on the mathematics that lies at the intersection of probability theory, statistical physics, combinatorics and computer science, this volume collects together lecture notes on recent developments in the area. The common ground of these subjects is perhaps best described by the three terms in the title: Random Walks, Random Fields and Disordered Systems. The specific topics covered include a study of Branching Brownian Motion from the perspective of disordered (spin-glass) systems, a detailed analysis of weakly self-avoiding random walks in four spatial dimensions via methods of field theory and the renormalization group, a study of phase transitions in disordered discrete structures using a rigorous version of the cavity method, a survey of recent work on interacting polymers in the ballisticity regime and, finally, a treatise on two-dimensional loop-soup models and their connection to conformally invariant systems and the Gaussian Free Field. The notes are aimed at early graduate students with a mod...

  18. Measurement of particle velocity using a mutual inductance technique

    International Nuclear Information System (INIS)

    Kerr, Stephen; Kirkpatrick, Douglas; Garden, Steven

    2004-01-01

    Preliminary work on the development of a novel method for the measurement of particle velocity is described. The technique relies on measurement of the mutual inductance between two coaxial coils, one stationary and the other perturbed by the shock wave. The moving coil is the gauge and is deposited on thin film. The method was developed to assist in the study of particle velocities in large samples of porous media surrounding an explosive charge. The technique does not require measurements to be taken in a region of uniform magnetic field and therefore dispenses with the need for Helmholtz coils, the size and cost of which can become prohibitive for large experiments. This has the added advantage of allowing measurements to be taken at points widely dispersed through a sample with relative ease. Measurements of particle velocity in porous media have been compared with those from co-located conventional electromagnetic particle velocity gauges with reasonable agreement

  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

    pended sediment dispersion patterns, in sequential two time lapsed images. .... face advective velocities consists essentially of iden- tifying the ... matrix is time consuming, a significant reduction .... Chauhan, P. 2002 Personal Communication.

  20. Measuring surface flow velocity with smartphones: potential for citizen observatories

    Science.gov (United States)

    Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik

    2014-05-01

    Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.

  1. Measurement bias of fluid velocity in molecular simulations

    International Nuclear Information System (INIS)

    Tysanner, Martin W.; Garcia, Alejandro L.

    2004-01-01

    In molecular simulations of fluid flow, the measurement of mean fluid velocity is considered to be a straightforward computation, yet there is some ambiguity in its definition. We show that in systems far from equilibrium, such as those with large temperature or velocity gradients, two commonly used definitions give slightly different results. Specifically, a bias can arise when computing the mean fluid velocity by measuring the mean particle velocity in a cell and averaging this mean over samples. We show that this bias comes from the correlation of momentum and density fluctuations in non-equilibrium fluids, obtain an analytical expression for predicting it, and discuss what system characteristics (e.g., number of particles per cell, temperature gradients) reduce or magnify the error. The bias has a physical origin so although we demonstrate it by direct simulation Monte Carlo (DSMC) computations, the same effect will be observed with other particle-based simulation methods, such as molecular dynamics and lattice gases

  2. Radar velocity determination using direction of arrival measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.; Bickel, Douglas L.; Naething, Richard M.; Horndt, Volker

    2017-12-19

    The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis. This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.

  3. Simultaneous Temperature and Velocity Diagnostic for Reacting Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A diagnostic technique is proposed for measuring temperature and velocity simultaneously in a high temperature reacting flow for aiding research in propulsion. The...

  4. Photoelectric Radial Velocities, Paper XVIII Spectroscopic Orbits for ...

    Indian Academy of Sciences (India)

    The fundamental origin of the work presented here rests with the radial-velocity spectrometer that .... surfaces inevitably degrade rather rapidly in the environment in which they are called ...... are not safe to incorporate in the data set here.

  5. Instability of shallow open channel flow with lateral velocity gradients

    Energy Technology Data Exchange (ETDEWEB)

    Lima, A C; Izumi, N, E-mail: adriano@eng.hokudai.ac.jp, E-mail: nizumi@eng.hokudai.ac.jp [River and Watershed Engineering Laboratory, Hokkaido University, Sapporo, 060-8628 (Japan)

    2011-12-22

    The turbulent flow in a wide rectangular open channel partially covered with vegetation is studied using linear stability analysis. In the base state normal flow condition, the water depth is constant and the transverse velocity vanishes, while there is a lateral gradient in the streamwise velocity with an inflexion point at the boundary between the vegetated zone and the main channel. The Reynolds stress is expressed by introducing the eddy viscosity, which is obtained from assuming a logarithmic distribution of the velocity near the bed. Perturbation expansions are introduced to the streamwise and transverse velocities, as well as to the water depth. The system of governing equations was solved in order to determine the maximum growth rate of the perturbations as a function of parameters which describe physical characteristics of the channel and the flow.

  6. Climate Velocity Can Inform Conservation in a Warming World.

    Science.gov (United States)

    Brito-Morales, Isaac; García Molinos, Jorge; Schoeman, David S; Burrows, Michael T; Poloczanska, Elvira S; Brown, Christopher J; Ferrier, Simon; Harwood, Tom D; Klein, Carissa J; McDonald-Madden, Eve; Moore, Pippa J; Pandolfi, John M; Watson, James E M; Wenger, Amelia S; Richardson, Anthony J

    2018-06-01

    Climate change is shifting the ranges of species. Simple predictive metrics of range shifts such as climate velocity, that do not require extensive knowledge or data on individual species, could help to guide conservation. We review research on climate velocity, describing the theory underpinning the concept and its assumptions. We highlight how climate velocity has already been applied in conservation-related research, including climate residence time, climate refugia, endemism, historic and projected range shifts, exposure to climate change, and climate connectivity. Finally, we discuss ways to enhance the use of climate velocity in conservation through tailoring it to be more biologically meaningful, informing design of protected areas, conserving ocean biodiversity in 3D, and informing conservation actions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Isotropic Optical Mouse Placement for Mobile Robot Velocity Estimation

    Directory of Open Access Journals (Sweden)

    Sungbok Kim

    2014-06-01

    Full Text Available This paper presents the isotropic placement of multiple optical mice for the velocity estimation of a mobile robot. It is assumed that there can be positional restriction on the installation of optical mice at the bottom of a mobile robot. First, the velocity kinematics of a mobile robot with an array of optical mice is obtained and the resulting Jacobian matrix is analysed symbolically. Second, the isotropic, anisotropic and singular optical mouse placements are identified, along with the corresponding characteristic lengths. Third, the least squares mobile robot velocity estimation from the noisy optical mouse velocity measurements is discussed. Finally, simulation results for several different placements of three optical mice are given.

  8. Using the load-velocity relationship for 1RM prediction.

    Science.gov (United States)

    Jidovtseff, Boris; Harris, Nigel K; Crielaard, Jean-Michel; Cronin, John B

    2011-01-01

    The purpose of this study was to investigate the ability of the load-velocity relationship to accurately predict a bench press 1 repetition maximum (1RM). Data from 3 different bench press studies (n = 112) that incorporated both 1RM assessment and submaximal load-velocity profiling were analyzed. Individual regression analysis was performed to determine the theoretical load at zero velocity (LD0). Data from each of the 3 studies were analyzed separately and also presented as overall group mean. Thereafter, correlation analysis provided quantification of the relationships between 1RM and LD0. Practically perfect correlations (r = ∼0.95) were observed in our samples, confirming the ability of the load-velocity profile to accurately predict bench press 1RM.

  9. Using cluster analysis to organize and explore regional GPS velocities

    Science.gov (United States)

    Simpson, Robert W.; Thatcher, Wayne; Savage, James C.

    2012-01-01

    Cluster analysis offers a simple visual exploratory tool for the initial investigation of regional Global Positioning System (GPS) velocity observations, which are providing increasingly precise mappings of actively deforming continental lithosphere. The deformation fields from dense regional GPS networks can often be concisely described in terms of relatively coherent blocks bounded by active faults, although the choice of blocks, their number and size, can be subjective and is often guided by the distribution of known faults. To illustrate our method, we apply cluster analysis to GPS velocities from the San Francisco Bay Region, California, to search for spatially coherent patterns of deformation, including evidence of block-like behavior. The clustering process identifies four robust groupings of velocities that we identify with four crustal blocks. Although the analysis uses no prior geologic information other than the GPS velocities, the cluster/block boundaries track three major faults, both locked and creeping.

  10. Shaping the distribution of vertical velocities of antihydrogen in GBAR

    Energy Technology Data Exchange (ETDEWEB)

    Dufour, G.; Lambrecht, A.; Reynaud, S. [CNRS, ENS, UPMC, Laboratoire Kastler-Brossel, Paris (France); Debu, P. [CEA-Saclay, Institut de Recherche sur les lois Fondamentales de l' Univers, Gif-sur-Yvette (France); Nesvizhevsky, V.V. [Institut Max von Laue-Paul Langevin, Grenoble (France); Voronin, A.Yu. [P.N. Lebedev Physical Institute, Moscow (Russian Federation)

    2014-01-15

    GBAR is a project aiming at measuring the freefall acceleration of gravity for antimatter, namely antihydrogen atoms (H). The precision of this timing experiment depends crucially on the dispersion of initial vertical velocities of the atoms as well as on the reliable control of their distribution.We propose to use a new method for shaping the distribution of the vertical velocities of H, which improves these factors simultaneously. The method is based on quantum reflection of elastically and specularly bouncing H with small initial vertical velocity on a bottom mirror disk, and absorption of atoms with large initial vertical velocities on a top rough disk.We estimate statistical and systematic uncertainties, and we show that the accuracy for measuring the free fall acceleration g of H could be pushed below 10{sup -3} under realistic experimental conditions. (orig.)

  11. Superluminal Velocities in the Synchronized Space-Time

    Directory of Open Access Journals (Sweden)

    Medvedev S. Yu.

    2014-07-01

    Full Text Available Within the framework of the non-gravitational generalization of the special relativity, a problem of possible superluminal motion of particles and signals is considered. It has been proven that for the particles with non-zero mass the existence of anisotropic light barrier with the shape dependent on the reference frame velocity results from the Tangherlini transformations. The maximal possible excess of neutrino velocity over the absolute velocity of light related to the Earth (using th e clock with instantaneous synchronization has been estimated. The illusoriness of t he acausality problem has been illustrated and conclusion is made on the lack of the upper limit of velocities of signals of informational nature.

  12. A phenomenological retention tank model using settling velocity distributions.

    Science.gov (United States)

    Maruejouls, T; Vanrolleghem, P A; Pelletier, G; Lessard, P

    2012-12-15

    Many authors have observed the influence of the settling velocity distribution on the sedimentation process in retention tanks. However, the pollutants' behaviour in such tanks is not well characterized, especially with respect to their settling velocity distribution. This paper presents a phenomenological modelling study dealing with the way by which the settling velocity distribution of particles in combined sewage changes between entering and leaving an off-line retention tank. The work starts from a previously published model (Lessard and Beck, 1991) which is first implemented in a wastewater management modelling software, to be then tested with full-scale field data for the first time. Next, its performance is improved by integrating the particle settling velocity distribution and adding a description of the resuspension due to pumping for emptying the tank. Finally, the potential of the improved model is demonstrated by comparing the results for one more rain event. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Crystal growth velocity in deeply undercooled Ni-Si alloys

    Science.gov (United States)

    Lü, Y. J.

    2012-02-01

    The crystal growth velocity of Ni95Si5 and Ni90Si10 alloys as a function of undercooling is investigated using molecular dynamics simulations. The modified imbedded atom method potential yields the equilibrium liquidus temperatures T L ≈ 1505 and 1387 K for Ni95Si5 and Ni90Si10 alloys, respectively. From the liquidus temperatures down to the deeply undercooled region, the crystal growth velocities of both the alloys rise to the maximum with increasing undercooling and then drop slowly, whereas the athermal growth process presented in elemental Ni is not observed in Ni-Si alloys. Instead, the undercooling dependence of the growth velocity can be well-described by the diffusion-limited model, furthermore, the activation energy associated with the diffusion from melt to interface increases as the concentration increases from 5 to 10 at.% Si, resulting in the remarkable decrease of growth velocity.

  14. Welding wire velocity modelling and control using an optical sensor

    DEFF Research Database (Denmark)

    Nielsen, Kirsten M.; Pedersen, Tom S.

    2007-01-01

    In this paper a method for controlling the velocity of a welding wire at the tip of the handle is described. The method is an alternative to the traditional welding apparatus control system where the wire velocity is controlled internal in the welding machine implying a poor disturbance reduction....... To obtain the tip velocity a dynamic model of the wire/liner system is developed and verified.  In the wire/liner system it turned out that backlash and reflections are influential factors. An idea for handling the backlash has been suggested. In addition an optical sensor for measuring the wire velocity...... at the tip has been constructed. The optical sensor may be used but some problems due to focusing cause noise in the control loop demanding a more precise mechanical wire feed system or an optical sensor with better focusing characteristics....

  15. Cerenkov detector for heavy-ion velocity measurements

    International Nuclear Information System (INIS)

    Olson, D.L.; Baumgartner, M.; Dufour, J.P.; Girard, J.G.; Greiner, D.E.; Lindstrom, P.J.; Symons, T.J.M.; Crawford, H.J.

    1984-08-01

    We have developed a highly sensitive velocity measuring detector using total-internal-reflection Cerenkov counters of a type mentioned by Jelly in 1958. If the velocity of the particle is above the threshold for total-internal-reflection these counters have a charge resolution of sigma = 0.18e for a 3mm thick glass radiator. For the velocity measurement we use a fused silica radiator so that the velocity of the particles are near the threshold for total-internal reflection. For momentum-analyzed projectile fragments of 1.6 GeV/nucleon 40 Ar, we have measured a mass resolution of sigma = 0.1u for isotope identification

  16. Cell wall pH and auxin transport velocity

    Science.gov (United States)

    Hasenstein, K. H.; Rayle, D.

    1984-01-01

    According to the chemiosmotic polar diffusion hypothesis, auxin pulse velocity and basal secretion should increase with decreasing cell wall pH. Experiments were designed to test this prediction. Avena coleoptile sections were preincubated in either fusicoccin (FC), cycloheximide, pH 4.0, or pH 8.0 buffer and subsequently their polar transport capacities were determined. Relative to controls, FC enhanced auxin (IAA) uptake while CHI and pH 8.0 buffer reduced IAA uptake. Nevertheless, FC reduced IAA pulse velocity while cycloheximide increased velocity. Additional experiments showed that delivery of auxin to receivers is enhanced by increased receiver pH. This phenomenon was overcome by a pretreatment of the tissue with IAA. Our data suggest that while acidic wall pH values facilitate cellular IAA uptake, they do not enhance pulse velocity or basal secretion. These findings are inconsistent with the chemiosmotic hypothesis for auxin transport.

  17. Limiting velocity of reconnection in a current layer

    International Nuclear Information System (INIS)

    Podgornyj, A.N.; Syrovatskij, S.I.

    1981-01-01

    Formation of a plasma current layer from a strong perturbation wave with the Mach magnetic number Msub(a)=1 is investigated numerically within the framework of magnetic hydrodynamics. It is shown that velocity of plasma flowing into the layer is established as small one as compared with the Alfven velocity. At the current layer boundary the Mach magnetic number Msub(a, c)=0.14-0.2. A great decrease in plasma velocity to the current layer results from the counterpressure of a magnetic field, intensity of which near the layer increases due to the storage of magnetic force lines which do not yet reconnect. Calculational results demonstrate the existence of limiting velocity of magnetic reconnection constituting tenth shares of the Mach magnetic number. Influence of this phenomenon on a character of reconnection in the Earth magnetosphere is discussed

  18. Shaping the distribution of vertical velocities of antihydrogen in GBAR

    CERN Document Server

    Dufour, G.; Lambrecht, A.; Nesvizhevsky, V.V.; Reynaud, S.; Voronin, A.Yu.

    2014-01-30

    GBAR is a project aiming at measuring the free fall acceleration of gravity for antimatter, namely antihydrogen atoms ($\\overline{\\mathrm{H}}$). Precision of this timing experiment depends crucially on the dispersion of initial vertical velocities of the atoms as well as on the reliable control of their distribution. We propose to use a new method for shaping the distribution of vertical velocities of $\\overline{\\mathrm{H}}$, which improves these factors simultaneously. The method is based on quantum reflection of elastically and specularly bouncing $\\overline{\\mathrm{H}}$ with small initial vertical velocity on a bottom mirror disk, and absorption of atoms with large initial vertical velocities on a top rough disk. We estimate statistical and systematic uncertainties, and show that the accuracy for measuring the free fall acceleration $\\overline{g}$ of $\\overline{\\mathrm{H}}$ could be pushed below $10^{-3}$ under realistic experimental conditions.

  19. Superluminal velocity of photons in a gravitational background

    International Nuclear Information System (INIS)

    Khriplovich, I.B.

    1994-01-01

    The influence of radiative corrections on the photon propagation in a gravitational background is investigated without the low-frequency assumption. The conclusion is made in this way that the velocity of light can exceed unity. 7 refs

  20. Anomalous cross-field velocities in a CIV laboratory experiment

    International Nuclear Information System (INIS)

    Axnaes, I.

    1988-10-01

    The axial and radial ion velocities and the electron radial velocity are determined in coaxial plasma gun operated under critical velocity conditions. The particle celocities are determined from probe measurement together with He I 3889 AA absolute intensity measurements and the consideration of the total momentum balance of the current sheet. The ions are found move axially and the electrons radially much faster than predicted by the E/B drift in the macroscopic fields. These results agree with what can be expected from the instability processes, which has earlier been proposed to operate in these experiments. It is therefore a direct experimental demonstration that instability processes have to be invoked not only for the electron heating, but also to explain the macroscopic velocities and currents. (author)