WorldWideScience

Sample records for ambient transverse velocity

  1. Transverse Spectral Velocity Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    array probe is used along with two different estimators based on the correlation of the received signal. They can estimate the velocity spectrum as a function of time as for ordinary spectrograms, but they also work at a beam-to-flow angle of 90°. The approach is validated using simulations of pulsatile...... flow using the Womersly–Evans flow model. The relative bias of the mean estimated frequency is 13.6% and the mean relative standard deviation is 14.3% at 90°, where a traditional estimator yields zero velocity. Measurements have been conducted with an experimental scanner and a convex array transducer....... A pump generated artificial femoral and carotid artery flow in the phantom. The estimated spectra degrade when the angle is different from 90°, but are usable down to 60° to 70°. Below this angle the traditional spectrum is best and should be used. The conventional approach can automatically be corrected...

  2. 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...

  3. Experimental investigation of transverse velocity estimation using cross-correlation

    DEFF Research Database (Denmark)

    Bjerngaard, Rasmus; Jensen, Jørgen Arendt

    2001-01-01

    A technique for estimating the full flow velocity vector has previously been presented by our group. Unlike conventional estimators, that only detect the axial component of the flow, this new method is capable of estimating the transverse velocity component. The method uses focusing along the flow....... A mean parabolic velocity profile was obtained for purely transverse flow with a mean bias to the true profile of -2.5% relative to the peak velocity and a standard deviation of 13.3% relative to the peak velocity. Twenty pulse-echo lines were used for each estimate and 18 profiles were obtained...... and the flow at an angle of 701 was successfully estimated....

  4. 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...... method Transverse Oscillation (TO), which combines estimates of the axial and the transverse velocity components in the scan plane, makes it possible to estimate the vector velocity of the blood regardless of the Doppler angle. The present study evaluates the TO method with magnetic resonance angiography...... +/- 1.7 ml and for MRA: 5.8 ml +/- 2.0 ml with the full range for TO: 3.4 ml - 9.5 ml and for MRA 3.0 ml - 10.8 ml. The correlation between the SV estimated by TO and MRA was 0.91 (p

  5. Data adaptive estimation of transversal blood flow velocities

    DEFF Research Database (Denmark)

    Pirnia, E.; Jakobsson, A.; Gudmundson, E.

    2014-01-01

    The examination of blood flow inside the body may yield important information about vascular anomalies, such as possible indications of, for example, stenosis. Current Medical ultrasound systems suffer from only allowing for measuring the blood flow velocity along the direction of irradiation......, posing natural difficulties due to the complex behaviour of blood flow, and due to the natural orientation of most blood vessels. Recently, a transversal modulation scheme was introduced to induce also an oscillation along the transversal direction, thereby allowing for the measurement of also...... the transversal blood flow. In this paper, we propose a novel data-adaptive blood flow estimator exploiting this modulation scheme. Using realistic Field II simulations, the proposed estimator is shown to achieve a notable performance improvement as compared to current state-of-the-art techniques....

  6. Improved Vector Velocity Estimation using Directional Transverse Oscillation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2015-01-01

    emissions at a 90 degrees beam-to-flow angle at a vessel depth of 30 mm. The standard deviation (SD) drops from 9.14% for TO to 5.4%, when using DTO. The bias is -5.05% and the angle is found within +/- 3.93 degrees. At 70 mm a relative SD of 7% is obtained, the bias is -1.74%, and the angle is found within......A method for estimating vector velocities using transverse oscillation (TO) combined with directional beamforming is presented. Directional Transverse Oscillation (DTO) is selfcalibrating, which increase the estimation accuracy and finds the lateral oscillation period automatically. A normal......, and a modified TO estimator can be used to find both the lateral and axial velocity. The approach is self-calibrating as the lateral oscillation period directly is estimated from the directional signal through a Fourier transform. The approach was implemented on the SARUS scanner using a BK Medical 8820e...

  7. Transverse Oscillation Vector Velocity Estimation using a Phased Array Transducer

    DEFF Research Database (Denmark)

    Marcher, Jønne; Pihl, Michael Johannes; Seerup, Gert

    2012-01-01

    greater than 100 mm. Tests at depths of 72 mm and 82 mm with a peak velocity of 0.5 m/s, showed a relative mean bias ~Bvx that varied from 0 % and to 21 % and a relative mean standard deviation ~vx that varied from 18 % and to 51 %. The investigation showed an increasing bias with respect to depth, which......The Transverse Oscillation method has shown its commercial feasibility, providing the user with 2D velocity information. Todays implementation on commercial ultrasound platforms only support linear array transducers and are limited in depth. Extending the implementation to a phased array transducer...... leaves room for optimization. Despite the bias, the method has shown to work and produce reliable results, and 2D velocity estimates are provided within the entire color-box down to a depth of more than 100 mm making vector velocity imaging possible in the entire heart....

  8. Phased-array vector velocity estimation using transverse oscillations

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Marcher, Jønne; Jensen, Jørgen Arendt

    2012-01-01

    A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical applicabil......A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical...... of the TO method using a phased-array transducer for vector velocity estimation is evaluated through simulation and flow-rig measurements are acquired using an experimental scanner. The vast number of calculations needed to perform flow simulations makes the optimization of the TO fields a cumbersome process......, 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....

  9. Velocity Estimation of the Main Portal Vein with Transverse Oscillation

    DEFF Research Database (Denmark)

    Brandt, Andreas Hjelm; Hansen, Kristoffer Lindskov; Nielsen, Michael Bachmann

    2015-01-01

    This study evaluates if Transverse Oscillation (TO) can provide reliable and accurate peak velocity estimates of blood flow the main portal vein. TO was evaluated against the recommended and most widely used technique for portal flow estimation, Spectral Doppler Ultrasound (SDU). The main portal...... vein delivers blood from the bowls to the liver, and patients with certain liver diseases have decreased flow in the portal vein. Errors in velocity estimation with SDU are well described, when the beam-to-flow angle is >70 degrees. TO estimates the flow angle independently and is not limited...... and subcostal were significantly different (intercostal mean SDU=0.202m/s, subcostal mean SDU=0.320m/s, pestimation...

  10. Shear velocity of the Rotokawa geothermal field using ambient noise

    Science.gov (United States)

    Civilini, F.; Savage, M. K.; Townend, J.

    2014-12-01

    Ambient noise correlation is an increasingly popular seismological technique that uses the ambient seismic noise recorded at two stations to construct an empirical Green's function. Applications of this technique include determining shear velocity structure and attenuation. An advantage of ambient noise is that it does not rely on external sources of seismic energy such as local or teleseismic earthquakes. This method has been used in the geothermal industry to determine the depths at which magmatic processes occur, to distinguish between production and non-production areas, and to observe seismic velocity perturbations associated with fluid extraction. We will present a velocity model for the Rotokawa geothermal field near Taupo, New Zealand, produced from ambient noise cross correlations. Production at Rotokawa is based on the "Rotokawa A" combined cycle power station established in 1997 and the "Nga Awa Purua" triple flash power plant established in 2010. Rotokawa Joint Venture, a partnership between Mighty River Power and Tauhara North No. 2 Trust currently operates 174 MW of generation at Rotokawa. An array of short period seismometers was installed in 2008 and occupies an area of roughly 5 square kilometers around the site. Although both cultural and natural noise sources are recorded at the stations, the instrument separation distance provides a unique challenge for analyzing cross correlations produced by both signal types. The inter-station spacing is on the order of a few kilometers, so waves from cultural sources generally are not coherent from one station to the other, while the wavelength produced by natural noise is greater than the station separation. Velocity models produced from these two source types will be compared to known geological models of the site. Depending on the amount of data needed to adequately construct cross-correlations, a time-dependent model of velocity will be established and compared with geothermal production processes.

  11. Comparison of Vector Velocity Imaging using Directional Beamforming and Transverse Oscillation for a Convex Array Transducer

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    Vector velocity imaging can reveal both the magnitude and direction of the blood velocity. Several techniques have been suggested for estimating the velocity, and this paper compares the performance for directional beamforming and transverse oscillation (TO) vector flow imaging (VFI). Data have b...

  12. Principle and performance of the transverse oscillation vector velocity technique in medical ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Pihl, Michael Johannes; Udesen, Jesper

    2010-01-01

    to the axial blood velocity. A major drawback is that only the axial velocity component is found. Often the lateral component is most important as blood vessels run parallel to the skin surface. The talk presents the transverse oscillation approach, which also can find the lateral velocity component by using...

  13. Transverse Oscillations for Phased Array Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2010-01-01

    of superficial blood vessels. To broaden the usability of the method, it should be expanded to a phased array geometry enabling vector velocity imaging of the heart. Therefore, the scan depth has to be increased to 10-15 cm. This paper presents suitable pulse echo fields (PEF). Two lines are beamformed...... into negative frequencies are used as metrics to assess estimator performance. At 10 cm’s depth for an initial setup, the relative mean bias and standard deviation are 9.1% and 9.5%, respectively. At a depth of 15 cm, the values are 20% and 13%, respectively. The PEF metric ER can be used to assess the bias...... (correlation coefficient, R: -0.76), and therefore predict estimator performance. CV is correlated with the standard deviation (R=0.74). The results demonstrate the potential for using a phased array for vector velocity imaging at larger depths, and potentially for imaging the heart....

  14. A Transverse Oscillation Approach for Estimation of Three-Dimensional Velocity Vectors, Part II: Experimental Validation

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev

    2014-01-01

    The 3-D transverse oscillation method is investigated by estimating 3-D velocities in an experimental flowrigsystem. Measurements of the synthesized transverse oscillatingfields are presented as well. The method employs a 2-D transducer; decouples the velocity estimation; and estimates the axial......, transverse, and elevation velocity components simultaneously. Data are acquired using a research ultrasound scanner. The velocity measurements are conducted with steady flow in sixteen different directions. For a specific flow direction with [α,β]= [45,15]°, the mean estimated velocity vector at the center...... of the vessel is (vx,vy,vz) = (33.8,34.5,15.2) ± (4.6,5.0,0.6)cm/s where the expected velocity is (34.2,34.2,13.0)cm/s. The velocity magnitude is 50.6 ± 5.2cm/s with a bias of 0.7cm/s.The flow angles α and β are estimated as 45.6 ± 4.9° and 17.6± 1.0°. Subsequently, the precision and accuracy are calculated...

  15. A transverse oscillation approach for estimation of three-dimensional velocity vectors, part II: experimental validation.

    Science.gov (United States)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2014-10-01

    The 3-D transverse oscillation method is investigated by estimating 3-D velocities in an experimental flow-rig system. Measurements of the synthesized transverse oscillating fields are presented as well. The method employs a 2-D transducer; decouples the velocity estimation; and estimates the axial, transverse, and elevation velocity components simultaneously. Data are acquired using a research ultrasound scanner. The velocity measurements are conducted with steady flow in sixteen different directions. For a specific flow direction with [α, ß] = [45, 15]°, the mean estimated velocity vector at the center of the vessel is (v(x), v(y), v(z)) = (33.8, 34.5, 15.2) ± (4.6, 5.0, 0.6) cm/s where the expected velocity is (34.2, 34.2, 13.0) cm/s. The velocity magnitude is 50.6 ± 5.2 cm/s with a bias of 0.7 cm/s. The flow angles α and ß are estimated as 45.6 ± 4.9° and 17.6 ± 1.0°. Subsequently, the precision and accuracy are calculated over the entire velocity profiles. On average for all direction, the relative mean bias of the velocity magnitude is -0.08%. For α and ß, the mean bias is -0.2° and -1.5°. The relative standard deviations of the velocity magnitude ranges from 8 to 16%. For the flow angles, the ranges of the mean angular deviations are 5° to 16° and 0.7° and 8°.

  16. New Developments in Vector Velocity Imaging using the Transverse Oscillation Approach

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Pihl, Michael Johannes; Olesen, Jacob Bjerring

    2013-01-01

    Vector velocity imaging using the Transverse Oscillation (TO) approach has recently been FDA approved for linear array transducers on a commercial platform. It can now be used clinically for studying the complex flow at e.g. bifurcations, valves, and the heart in real time. Several clinical...

  17. High Frame Rate Vector Velocity Estimation using Plane Waves and Transverse Oscillation

    DEFF Research Database (Denmark)

    Jensen, Jonas; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2015-01-01

    This paper presents a method for estimating 2-D vector velocities using plane waves and transverse oscillation. The approach uses emission of a low number of steered plane waves, which result in a high frame rate and continuous acquisition of data for the whole image. A transverse oscillating field...... in a flow rig phantom is scanned at beam-to-flow angles of 90, 75, and 60◦ . The relative bias is between -1.4 % and -5.8 % and the relative std. between 5 % and 8.2 % for the lateral velocity component at the measured beam-to-flow angles. The estimated flow angle is 73.4◦± 3.6◦ for the measurement at 75...

  18. Vector Velocity Estimation for Portable Ultrasound using Directional Transverse Oscillation and Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    di Ianni, Tommaso; Hemmsen, Martin Christian; Jensen, Jørgen Arendt

    2016-01-01

    In this paper, a vector flow imaging method is presented, which combines the directional transverse oscillation approach with synthetic aperture sequential beamforming to achieve an efficient estimation of the velocities. A double oscillating field is synthesized using two sets of focused emissions...... separated by a distance in the lateral direction. A low resolution line (LRL) is created for each emission in the first stage beamformer, and a second beamformer provides the high resolution data used for the velocity estimation. The method makes it possible to have continuously available data in the whole...... image. Therefore, high and low velocities can be estimated with a high frame rate and a low standard deviation. The first stage is a fixed-focus beamformer that can be integrated in the transducer handle, enabling the wireless transmission of the LRLs. The approach does not require any angle...

  19. Blood flow velocity in the Popliteal Vein using Transverse Oscillation Ultrasound

    DEFF Research Database (Denmark)

    Bechsgaard, Thor; Lindskov Hansen, Kristoffer; Brandt, Andreas Hjelm

    2016-01-01

    Chronic venous disease is a common condition leading to varicose veins, leg edema, post-thrombotic syndrome and venous ulcerations. Ultrasound (US) is the main modality for examination of venous disease. Color Doppler and occasionally spectral Doppler US (SDUS) are used for evaluation of the venous...... flow. Peak velocities measured by SDUS are rarely used in a clinical setting for evaluating chronic venous disease due to inadequate reproducibility mainly caused by the angle dependency of the estimate. However, estimations of blood velocities are of importance in characterizing venous disease....... Transverse Oscillation US (TOUS), a non-invasive angle independent method, has been implemented on a commercial scanner. TOUS’s advantage compared to SDUS is a more elaborate visualization of complex flow. The aim of this study was to evaluate, whether TOUS perform equal to SDUS for recording velocities...

  20. Improving Seismic Velocity Models with Constraints from Autocorrelation of Ambient Seismic Noise and Signal

    Science.gov (United States)

    2016-03-24

    AFRL-RV-PS- AFRL-RV-PS- TR-2016-0098 TR-2016-0098 IMPROVING SEISMIC VELOCITY MODELS WITH CONSTRAINTS FROM AUTOCORRELATION OF AMBIENT SEISMIC ...TYPE Final Report 3. DATES COVERED (From - To) 24 Apr 2014 – 24 Mar 2016 4. TITLE AND SUBTITLE Improving Seismic Velocity Models with Constraints from...Autocorrelation of Ambient Seismic Noise and Signal 5a. CONTRACT NUMBER FA9453-14-C-0214 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6

  1. Quantification of displacement and velocity noise in vibrometer measurements on transversely moving or rotating surfaces

    Science.gov (United States)

    Dräbenstedt, Alexander

    2007-06-01

    The heterodyne interferometer (vibrometer) is a well established technique for measuring all kinds of mechanical vibrations in a broad range of applications. The non-contact measurement principle relies upon the Doppler (or phase-) shift that laser light experiences when it is reflected by the vibrating surface. The speckle nature of the reflected light imposes problems and creates additional measurement noise if the object is moving transversely through the laser spot or is rotating around an axis perpendicular to the laser direction. Another implication that can arise is cross coupling from in-plane vibrations into the out-of-plane measurement direction when small in-plane vibrations are present. A model is presented in this paper that describes the origin of these disturbances. Using this model it is possible to quantify the amplitude spectrum of the noise in displacement and velocity measurements. This enables the user to calculate the limits of resolvable vibration amplitudes when transverse motion is present. The results of the model have been confirmed well by measurements. In addition, the influence of the surface roughness and beam inclination on the out-of-plane vibration measurements at a tilted surface is investigated. The conditions for the measurability of the profile of a transversely moving surface are derived in this work. It is discussed that the R q-roughness parameter has to be less than λ/4 to obtain the slope information in the speckle-perturbed interferometer signal.

  2. Continuous Gait Velocity Analysis Using Ambient Sensors in a Smart Home

    NARCIS (Netherlands)

    Nait Aicha, A.; Englebienne, G.; Kröse, B.; De Ruyter, B.; Kameas, A.; Chatzimisios, P.; Mavrommati, I.

    2015-01-01

    We present a method for measuring gait velocity using data from an existing ambient sensor network. Gait velocity is an important predictor of fall risk and functional health. In contrast to other approaches that use specific sensors or sensor configurations our method imposes no constraints on the

  3. Convex Array Vector Velocity Imaging Using Transverse Oscillation and Its Optimization

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Brandt, Andreas Hjelm; Bachmann Nielsen, Michael

    2015-01-01

    array probe (pitch 0.33 mm) is used in both simulations and measurements. A parabolic velocity profile is simulated at a beam-to-flow angle of 90°. The optimization routine changes the lateral oscillation period λx as a function of depth to yield the best possible estimates based on the energy ratio...... between positive and negative spatial frequencies in the ultrasound field. The energy ratio is reduced from −17.1 dB to −22.1 dB. Parabolic profiles are estimated on simulated data using 16 emissions. The optimization gives a reduction in standard deviation from 8.81% to 7.4% for 16 emissions......, with a reduction in lateral velocity bias from −15.93% to 0.78% at 90° (transverse flow) at a depth of 40 mm. Measurements have been performed using the experimental ultrasound scanner and a convex array transducer. A bias of −0.93% was obtained at 87° for a parabolic velocity profile along with a standard...

  4. Optimization of Transverse Oscillating Fields for Vector Velocity Estimation with Convex Arrays

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2013-01-01

    A method for making Vector Flow Images using the transverse oscillation (TO) approach on a convex array is presented. The paper presents optimization schemes for TO fields for convex probes and evaluates their performance using Field II simulations and measurements using the SARUS experimental...... scanner. A 3 MHz 192 elements convex array probe (pitch 0.33 mm) is used in both simulations and measurements. An F-number of 5 is used in transmit and two 32 element wide peaks are used in receive separated by 96 elements between peaks. Parabolic velocity profiles are simulated at beam-to-flow angles......) at a depth of 40 mm. Measurements have been made using the SARUS experimental ultrasound scanner and a BK Medical 8820e convex array transducer. Sixty-four elements was used in transmit and 2 x 32 elements in receive for creating a color flow map image of a flow rig phantom with a laminar, parabolic flow...

  5. Migration velocity analysis using a transversely isotropic medium with tilt normal to the reflector dip

    KAUST Repository

    Alkhalifah, T.

    2010-06-13

    A transversely isotropic model in which the tilt is constrained to be normal to the dip (DTI model) allows for simplifications in the imaging and velocity model building efforts as compared to a general TTI model. Though this model, in some cases, can not be represented physically like in the case of conflicting dips, it handles all dips with the assumption of symmetry axis normal to the dip. It provides a process in which areas that meet this feature is handled properly. We use efficient downward continuation algorithms that utilizes the reflection features of such a model. For lateral inhomogeneity, phase shift migration can be easily extended to approximately handle lateral inhomogeneity, because unlike the general TTI case the DTI model reduces to VTI for zero dip. We also equip these continuation algorithms with tools that expose inaccuracies in the velocity. We test this model on synthetic data of general TTI nature and show its resilience even couping with complex models like the recently released anisotropic BP model.

  6. A Transverse Oscillation Approach for Estimation of Three-Dimensional Velocity Vectors, Part I: Concept and Simulation Study

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2014-01-01

    A method for 3-D velocity vector estimation us - ing transverse oscillations is presented. The method employs a 2-D transducer and decouples the velocity estimation into three orthogonal components, which are estimated simultane - ously and from the same data. The validity of the method...... also reveals, that the velocity estimation breaks down with an SNR between −6 and −3 dB. In terms of computational load, the estimation of the three velocity components requires 0.75 billion floating point operations per second (0.75 Gflops) for a realistic setup. This is well within the capability...

  7. Surface wave group velocity in the Osaka sedimentary basin, Japan, estimated using ambient noise cross-correlation functions

    Science.gov (United States)

    Asano, Kimiyuki; Iwata, Tomotaka; Sekiguchi, Haruko; Somei, Kazuhiro; Miyakoshi, Ken; Aoi, Shin; Kunugi, Takashi

    2017-08-01

    Inter-station cross-correlation functions estimated using continuous ambient noise or microtremor records were used to extract the seismic wave propagation characteristics of the Osaka sedimentary basin, Japan. Temporary continuous observations were conducted at 15 sites in the Osaka basin between 2011 and 2013. The data were analyzed using seismic interferometry. The target period range was 2-8 s. Cross-correlations between all of the possible station pairs were calculated and stacked to produce a year-long data set, and Rayleigh wave signals in the vertical and radial components and Love wave signals in the transverse component were identified from the results. Simulation of inter-station Green's functions using the finite difference method was conducted to check the performance of the current three-dimensional velocity structure model. The measured time lag between the observed and theoretical Green's functions was less than 2 s for most station pairs, which is less than the wave period of interest in the target frequency range. Group velocity tomography was applied to group delay times estimated by means of multiple filter analysis. The estimated group velocities for longer periods of 5-8 s exhibited spatial variation within the basin, which is consistent with the bedrock depth distribution; however, the group velocities for shorter periods of 2-3 s were almost constant over the studied area. The waveform and group velocity information obtained by seismic interferometry analysis can be useful for future reconstruction of a three-dimensional velocity structure model in the Osaka basin.[Figure not available: see fulltext.

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

    DEFF Research Database (Denmark)

    Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie

    2012-01-01

    We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one met...

  9. Electroosmotic velocity and electric conductivity in a fibrous porous medium in the transverse direction.

    Science.gov (United States)

    Keh, Huan J; Wu, Yi Y

    2011-07-28

    The steady electroosmosis and electric conduction in a fibrous medium constructed by a homogeneous array of parallel, identical, charged, circular cylinders filled with an electrolyte solution is analytically examined. The imposed electric field is constant and normal to the axes of the cylinders. The electric double layer surrounding each dielectric cylinder may have an arbitrary thickness relative to the radius of the cylinder. A unit cell model that allows for the overlap of the double layers of adjacent cylinders is employed. The electrokinetic equations that govern the ionic concentration distributions, the electrostatic potential profile, and the fluid flow field in the electrolyte solution surrounding the charged cylinder in a cylindrical cell are linearized assuming that the system is only slightly distorted from equilibrium. Through the use of a regular perturbation method, these linearized equations are solved with the surface charge density (or zeta potential) of the cylinder as the small perturbation parameter. Analytical expressions for the electroosmotic velocity of the fluid solution and the effective electric conductivity in the array of cylinders are obtained in closed forms as functions of the porosity of the fiber matrix and other characteristics of the porous system. Comparisons of the results of the cell model with different conditions at the outer boundary of the cell are made. The cell model predicts that, under otherwise identical conditions, the electric conductivity in a porous medium composed of an array of parallel cylinders in the transverse direction in general is smaller than that of a suspension of spheres, but there are some exceptions. The effect of interactions among the cylinders or spheres on the effective conductivity can be significant under appropriate conditions. © 2011 American Chemical Society

  10. 3D shear wave velocity structure revealed with ambient noise tomography on a DAS array

    Science.gov (United States)

    Zeng, X.; Thurber, C. H.; Wang, H. F.; Fratta, D.

    2017-12-01

    An 8700-m Distributed Acoustic Sensing (DAS) cable was deployed at Brady's Hot Springs, Nevada in March 2016 in a 1.5 by 0.5 km study area. The layout of the DAS array was designed with a zig-zag geometry to obtain relatively uniform areal and varied angular coverage, providing very dense coverage with a one-meter channel spacing. This array continuously recorded signals of a vibroseis truck, earthquakes, and traffic noise during the 15-day deployment. As shown in a previous study (Zeng et al., 2017), ambient noise tomography can be applied to DAS continuous records to image shear wave velocity structure in the near surface. To avoid effects of the vibroseis truck operation, only continuous data recorded during the nighttime was used to compute noise cross-correlation functions for channel pairs within a given linear segment. The frequency band of whitening was set at 5 to 15 Hz and the length of the cross-correlation time window was set to 60 second. The phase velocities were determined using the multichannel analysis of surface waves (MASW) methodology. The phase velocity dispersion curve was then used to invert for shear wave velocity profiles. A preliminarily velocity model at Brady's Hot Springs (Lawrence Livermore National Laboratory, 2015) was used as the starting model and the sensitivity kernels of Rayleigh wave group and phase velocities were computed with this model. As the sensitivity kernel shows, shear wave velocity in the top 200 m can be constrained with Rayleigh wave group and phase velocities in our frequency band. With the picked phase velocity data, the shear wave velocity structure can be obtained via Occam's inversion (Constable et al., 1987; Lai 1998). Shear wave velocity gradually increases with depth and it is generally faster than the Lawrence Livermore National Laboratory (2015) model. Furthermore, that model has limiting constraints at shallow depth. The strong spatial variation is interpreted to reflect the different sediments and

  11. High resolution Rayleigh wave group velocity tomography in North-China from ambient seismic noise

    International Nuclear Information System (INIS)

    Fang Lihua; Wu Jianping; Ding Zhifeng; Panza, G.F.

    2009-03-01

    This study presents the results of the Rayleigh wave group velocity tomography in North-China performed using ambient seismic noise observed at 190 broadband and 10 very broadband stations of the North-China Seismic Array. All available vertical component time-series for the 14 months span between January, 2007 and February, 2008 are cross-correlated to obtain empirical Rayleigh wave Green functions that are subsequently processed, with the multiple filter method, to isolate the group velocity dispersion curves of the fundamental mode of Rayleigh wave. Tomographic maps, with a grid spacing of 0.25 deg. x 0.25 deg., are computed at the periods of 4.5s, 12s, 20s, 28s. The maps at short periods reveal an evident lateral heterogeneity in the crust of North-China, quite well in agreement with known geological and tectonic features. The North China Basin is imaged as a broad low velocity area, while the Taihangshan and Yanshan uplifts and Ordos block are imaged as high velocity zones, and the Quaternary intermountain basins show up as small low-velocity anomalies. The group velocity contours at 4.5s, 12s and 20s are consistent with the Bouguer gravity anomalies measured in the area of the Taihangshan fault, that cuts through the lower crust at least. Most of the historical strong earthquakes (M≥6.0) are located where the tomographic maps show zones with moderate velocity gradient. (author)

  12. Ion temperature gradient driven mode in presence of transverse velocity shear in magnetized plasmas

    DEFF Research Database (Denmark)

    Chakrabarti, N.; Juul Rasmussen, J.; Michelsen, Poul

    2005-01-01

    The effect of sheared poloidal flow on the toroidal branch of the ion temperature gradient driven mode of magnetized nonuniform plasma is studied. A novel "nonmodal" calculation is used to analyze the problem. It is shown that the transverse shear flow considerably reduced the growth of the insta......The effect of sheared poloidal flow on the toroidal branch of the ion temperature gradient driven mode of magnetized nonuniform plasma is studied. A novel "nonmodal" calculation is used to analyze the problem. It is shown that the transverse shear flow considerably reduced the growth...

  13. Magmatism on rift flanks: Insights from ambient noise phase velocity in Afar region

    Science.gov (United States)

    Korostelev, Félicie; Weemstra, Cornelis; Leroy, Sylvie; Boschi, Lapo; Keir, Derek; Ren, Yong; Molinari, Irene; Ahmed, Abdulhakim; Stuart, Graham W.; Rolandone, Frédérique; Khanbari, Khaled; Hammond, James O. S.; Kendall, J. M.; Doubre, Cécile; Ganad, Ismail Al; Goitom, Berhe; Ayele, Atalay

    2015-04-01

    During the breakup of continents in magmatic settings, the extension of the rift valley is commonly assumed to initially occur by border faulting and progressively migrate in space and time toward the spreading axis. Magmatic processes near the rift flanks are commonly ignored. We present phase velocity maps of the crust and uppermost mantle of the conjugate margins of the southern Red Sea (Afar and Yemen) using ambient noise tomography to constrain crustal modification during breakup. Our images show that the low seismic velocities characterize not only the upper crust beneath the axial volcanic systems but also both upper and lower crust beneath the rift flanks where ongoing volcanism and hydrothermal activity occur at the surface. Magmatic modification of the crust beneath rift flanks likely occurs for a protracted period of time during the breakup process and may persist through to early seafloor spreading.

  14. MSNoise: a Python Package for Monitoring Seismic Velocity Changes using Ambient Seismic Noise

    Science.gov (United States)

    Lecocq, Thomas; Caudron, Corentin; Brenguier, Florent

    2014-05-01

    We present MSNoise, a complete software suite to compute relative seismic velocity changes under a seismic network, using ambient seismic noise. The whole is written in Python, from the monitoring of data archives, to the production of high quality figures. All steps have been optimized to only compute the necessary steps and to use 'job'-based processing. All steps can be changed by matching the in/outs. MSNoise exposes an API for communication with the data archive and the database. We present a validation of the software on a dataset acquired during the UnderVolc project on the Piton de la Fournaise Volcano, La Réunion Island, France, for which precursory relative changes of seismic velocity are visible for three eruptions betwee 2009 and 2011. MSNoise is available on http://www.msnoise.org

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

    Science.gov (United States)

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

    2014-12-01

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

  16. Estimation of blood velocity vectors using transverse ultrasound beam focusing and cross-correlation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Lacasa, Isabel Rodriguez

    1999-01-01

    Modern ultrasound scanners estimate the blood velocity by tracking the movement of the blood scatterers along the ultrasound beam. This is done by emitting pulsed ultrasound fields and finding the shift in position from pulse to pulse by correlating the received signals. Only the velocity component...... in a correlation estimator to find the velocity across the beam. This approach is extended in this paper by making beamforming along the direction of the flow. A fairly broad beam is emitted and the received signal is then focused along a selected direction. This direction can be along the ultrasound beam...

  17. Efficient focusing scheme for transverse velocity estimation using cross-correlation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2001-01-01

    simulations with Field II. A 64-elements, 5 MHz linear array was used. A parabolic velocity profile with a peak velocity of 0.5 m/s was considered for different angles between the flow and the ultrasound beam and for different emit foci. At 60 degrees the relative standard deviation was 0.58 % for a transmit...... of the flow. Here a weakly focused transmit field was used along with a simple delay-sum beamformer. A modified method for performing the focusing by employing a special calculation of the delays is introduced, so that a focused emission can be used. The velocity estimation was studied through extensive...

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

    Directory of Open Access Journals (Sweden)

    Chun-Hsiang Kuo

    2015-01-01

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

  19. Rayleigh wave group-velocity across the Dominican Republic and Puerto Rico from ambient noise tomography

    Science.gov (United States)

    Quiros, D.; Pulliam, J.; Polanco Rivera, E.; Huerfano Moreno, V. A.

    2017-12-01

    The eastern North America-Caribbean (NA-CAR) plate boundary near the islands of Hispaniola (which is comprised of the Dominican Republic and Haiti) and Puerto Rico is a complex transition zone in which strain is accommodated by two transform fault systems and oblique subduction. In 2013, scientists from Baylor University, the Autonomous University of Santo Domingo, and the Puerto Rico Seismic Network deployed 16 broadband stations on the Dominican Republic to expand the local permanent network. The goal of the Greater Antilles Seismic Program (GrASP) is to combine its data with that from permanent networks in Puerto Rico, Haiti, Cuba, the Cayman Islands, and Jamaica to develop a better understanding of the crust and upper mantle structure in the Northeastern Caribbean (Greater Antilles). One important goal of GrASP is to develop robust velocity models that can be used to improve earthquake location and seismic hazard efforts. In this study, we focus on obtaining Rayleigh wave group velocity maps from ambient noise tomography. By cross-correlating ambient seismic noise recorded at 53 stations between 2010 to present, we obtain Green's functions between 1165 pairs of stations. From these, we obtain dispersion curves by the application of FTAN methods with phase-matched filtering. Selection criteria depend on the signal-to-noise ratio and seasonal variability, with further filtering done by rejecting velocities incompatible with maps produced from overdamped tomographic inversions. Preliminary dispersion maps show strong correlations with large-scale geological and tectonic features for periods between 5 - 20 s, such as the Cordillera Central in both the Dominican Republic and Puerto Rico, the Mona Passage, and the NA-CAR subduction zone. Ongoing efforts focus on including shorter periods in Puerto Rico as its denser station distribution could allow us to retrieve higher resolution group velocity maps.

  20. Two-receiver measurements of phase velocity: cross-validation of ambient-noise and earthquake-based observations

    NARCIS (Netherlands)

    Kästle, Emanuel D.; Soomro, Riaz; Weemstra, C.; Boschi, Lapo; Meier, Thomas

    2016-01-01

    Phase velocities derived from ambient-noise cross-correlation are compared with phase velocities calculated from cross-correlations of waveform recordings of teleseismic earthquakes whose epicentres are approximately on the station–station great circle. The comparison is conducted both for Rayleigh

  1. Electrogravitational stability of oscillating streaming fluid cylinder ambient with a transverse varying electric field

    Directory of Open Access Journals (Sweden)

    Hasan Alfaisal

    2011-01-01

    Full Text Available Abstract The electrogravitational instability of a dielectric oscillating streaming fluid cylinder surrounded by tenuous medium of negligible motion pervaded by transverse varying electric field has been investigated for all the perturbation modes. The model is governed by Mathieu second-order integro-differential equation. Some limiting cases are recovering from the present general one. The self-gravitating force is destabilizing only in the axisymmetric perturbation for long wavelengths, while, the axial electric field interior, the fluid has strong destabilizing effect for all short and long wavelengths. The transverse field is strongly stabilizing. In the case of non-axisymmetric perturbation, the self-gravitating force is stabilizing for short and long waves, while the electric field has stabilizing effect on short waves.

  2. Shear-wave velocity of marine sediments offshore Taiwan using ambient seismic noise

    Science.gov (United States)

    Lin, Yu-Tse; Lin, Jing-Yi; Kuo-Chen, Hao; Yeh, Yi-Chin; Cheng, Win-Bin

    2017-04-01

    Seismic ambient noise technology has many advantages over the traditional two-station method. The most important one is that noise is happening all the time and it can be widely and evenly distributed. Thus, the Green's Function of any station pair can be obtained through the data cross-correlation process. Many related studies have been performed to estimate the velocity structures based on the inland area. Only a few studies were reported for the marine area due to the relatively shorter recording time of ocean bottom seismometers (OBS) deployment and the high cost of the marine experiment. However, the understanding about the shear-wave velocity (Vs) of the marine sediments is very crucial for the hazard assessment related to submarine landslides, particularly with the growing of submarine resources exploration. In this study, we applied the ambient noise technique to four OBS seismic networks located offshore Taiwan in the aim of getting more information about the noise sources and having the preliminary estimation for the Vs of the marine sediments. Two of the seismic networks were deployed in the NE part of Taiwan, near the Ryukyu subduction system, whereas the others were in the SW area, on the continental margin rich in gas hydrate. Generally, ambient seismic noise could be associated with wind, ocean waves, rock fracturing and anthropogenic activity. In the southwestern Taiwan, the cross-correlation function obtained from two seismic networks indicate similar direction, suggestion that the source from the south part of the network could be the origin of the noise. However, the two networks in the northeastern Taiwan show various source direction, which could be caused by the abrupt change of bathymetry or the volcanic degassing effect frequently observed by the marine geophysical method in the area. The Vs determined from the dispersion curve shows a relatively higher value for the networks in the Okinawa Trough (OT) off NE Taiwan than that in the

  3. Real-Time GPU Implementation of Transverse Oscillation Vector Velocity Flow Imaging

    DEFF Research Database (Denmark)

    Bradway, David; Pihl, Michael Johannes; Krebs, Andreas

    2014-01-01

    Rapid estimation of blood velocity and visualization of complex flow patterns are important for clinical use of diagnostic ultrasound. This paper presents real-time processing for two-dimensional (2-D) vector flow imaging which utilizes an off-the-shelf graphics processing unit (GPU). In this work...... vector flow acquisition takes 2.3 milliseconds seconds on an Advanced Micro Devices Radeon HD 7850 GPU card. The detected velocities are accurate to within the precision limit of the output format of the display routine. Because this tool was developed as a module external to the scanner’s built...

  4. A seismic waves velocity model for Gran Canaria Island from ambient noise correlations

    Science.gov (United States)

    García-Jerez, Antonio; Almendros, Javier; Martínez-Arévalo, Carmen; de Lis Mancilla, Flor; Luzón, Francisco; Carmona, Enrique; Martín, Rosa; Sánchez, Nieves

    2014-05-01

    We have analysed continuous ambient seismic noise recorded by a temporary array in Gran Canaria (Canary Islands, Spain) in order to find a velocity model for the top few kilometers. The SISTEVOTENCAN-IGN seismic array consisted of five broadband stations surrounding a sixth central one placed close to Pico de las Nieves, at the center of the island. The array had a radius of 12-14 km, with interstation distances ranging from 10 to 27 km. This network was operative from December 2009 to November 2011. The Green's functions between the 15 pairs of stations have been estimated in the time domain by stacking cross-correlations of 60-s time windows for the whole recording period (~2 years). The effects of several processing adjustments such as 1-bit normalization and spectral whitening are discussed. We observe significant differences (mainly in amplitude) between causal and acausal parts of the estimated Green's functions, which can be associated to an uneven distribution of the seismic noise sources. The application of a phase-matched filter based on an average dispersion curve allowed the effective reduction of some spurious early arrivals and the selection of fundamental-mode Rayleigh wave pulses, making possible an automatic extraction of their group velocities. Then, Rayleigh-wave dispersion curves were retrieved for the set of paths by using frequency-time analysis (FTAN) as well as by following the procedure described by Herrin and Goforth (1977, BSSA) based on the iterative fitting of a phase-matched filter which optimally undisperses the signal. Reliable curves were obtained from 1 s to 6-7 s with group velocities ranging between 1.5 and 2.2 km/s. Some lateral variations in velocity have been detected in spite of the limited spatial coverage and path density, which substantially restricted the resolution. A mean S-wave velocity model has been inverted for this area down to ~3 km.

  5. Ambient noise tomography of Ecuador: Fore- and back-arc velocity structure and radial anisotropy

    Science.gov (United States)

    Lynner, C.; Beck, S. L.; Porritt, R.; Meltzer, A.; Alvarado, A. P.; Gabriela, P.; Ruiz, M. C.; Hoskins, M.; Stachnik, J.; Rietbrock, A.; Leon-Rios, S.; Regnier, M. M.; Agurto-Detzel, H.; Font, Y.; Charvis, P.

    2017-12-01

    In northern South America, the oceanic Nazca plate subducts beneath the South American continent, giving rise to the high mountains of the northern Andes. The Ecuador subduction zone has a history of large megathrust earthquakes, most recently the Mw=7.8 April 16, 2016, Pedernales earthquake. The volcanic arc in Ecuador is broad with active volcanoes along both the western and eastern cordilleras. Many of these volcanoes surround the city of Quito putting millions of people at risk. A recent international broadband aftershock deployment was conducted for approximately one year after the Pedernales mainshock and this data combined with a sub-set of data from from the permanent IGEPN national network provide an ideal data set to use for ambient noise tomography (ANT) to constrain absolute Vsh and Vsv across Ecuador. ANT studies use noise-generated surface wave dispersion measurements to invert for 3D shear velocity in the crust. Having a precise understanding of crustal velocity structure is necessary to advance a number of projects, including better earthquake locations of the April 16, 2016 Pedernales-earthquake aftershock sequence and identifying large-scale partial melt zones associated with the active volcanic arc. The majority of ANT studies use only Rayleigh waves to constrain Vsv structure. Initial Rayleigh wave ANT results, using periods between 8 and 40 seconds, show a fast phase velocities for the forearc and much slower phase velocities for the high elevation volcanic arc. Including Love wave dispersion measurements can improve overall crustal velocity models, as well as provide constraints on radial anisotropy. Radial anisotropy can develop in a variety of ways but most typically arises from the deformation-induced alignment of anisotropic minerals. Radial anisotropy, therefore, can inform on patterns of ductile crustal flow. Strong radial anisotropy at mid-crustal depths from ANT has already been observed south of Ecuador, in the Central Andean Plateau

  6. Velocity, bathymetry, and transverse mixing characteristics of the Ohio River upstream from Cincinnati, Ohio, October 2004-March 2006

    Science.gov (United States)

    Koltun, G.F.; Ostheimer, Chad J.; Griffin, Michael S.

    2006-01-01

    Velocity, bathymetry, and transverse (cross-channel) mixing characteristics were studied in a 34-mile study reach of the Ohio River extending from the lower pool of the Captain Anthony Meldahl Lock and Dam, near Willow Grove, Ky, to just downstream from the confluence of the Licking and Ohio Rivers, near Newport, Ky. Information gathered in this study ultimately will be used to parameterize hydrodynamic and water-quality models that are being developed for the study reach. Velocity data were measured at an average cross-section spacing of about 2,200 feet by means of boat-mounted acoustic Doppler current profilers (ADCPs). ADCP data were postprocessed to create text files describing the three-dimensional velocity characteristics in each transect. Bathymetry data were measured at an average transect spacing of about 800 feet by means of a boat-mounted single-beam echosounder. Depth information obtained from the echosounder were postprocessed with water-surface slope and elevation information collected during the surveys to compute stream-bed elevations. The bathymetry data were written to text files formatted as a series of space-delimited x-, y-, and z-coordinates. Two separate dye-tracer studies were done on different days in overlapping stream segments in an 18.3-mile section of the study reach to assess transverse mixing characteristics in the Ohio River. Rhodamine WT dye was injected into the river at a constant rate, and concentrations were measured in downstream cross sections, generally spaced 1 to 2 miles apart. The dye was injected near the Kentucky shoreline during the first study and near the Ohio shoreline during the second study. Dye concentrations were measured along transects in the river by means of calibrated fluorometers equipped with flow-through chambers, automatic temperature compensation, and internal data loggers. The use of flow-through chambers permitted water to be pumped continuously out of the river from selected depths and through the

  7. Magmatism on rift flanks: insights from Ambient-Noise Phase-velocity in Afar region

    Science.gov (United States)

    Korostelev, Félicie; Weemstra, Cornelis; Leroy, Sylvie; Boschi, Lapo; Ren, Yong; Ahmed, Abdulhakim; Keir, Derek; Stuart, Graham W.; Rolandone, Frédérique; Khanbari, Khaled; Hammond, James O. S.; Kendall, J. Michael; Doubre, Cécile; Ganad, Ismail Al

    2015-04-01

    During the breakup of continent in the presence of magma, strain is commonly assumed to initially occur by border faulting, and progressively migrate in space and time towards axial magma intrusion. Magmatic processes near the rift flanks are commonly ignored. We present phase-velocity maps of the crust and uppermost mantle of the conjugate margins of the southern Red Sea (Afar and Yemen) using ambient noise tomography to constrain crustal modification during breakup. Our images show that the low seismic velocities characterize not only upper crust beneath the axial volcanic systems, but also both upper and lower crust beneath rift flanks where ongoing volcanism and hydrothermal activity occurs at the surface. The results show that magmatic modification of the crust beneath rift flanks likely occurs for a protracted period of time during the breakup process, and may persist through to early seafloor spreading. Since ongoing flank magmatism during breakup impacts the thermal evolution of the lithosphere, it has implications for the subsidence history of the rift.

  8. Preliminary comparison between real-time in-vivo spectral and transverse oscillation velocity estimates

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per

    2011-01-01

    angles and std were calculated { 52±18 ; 55±23 ; 60±16 }°. Spectral angles { 52 ; 56 ; 52 }° were obtained from the B-mode images. Obtained values are: PSTO { 76±15 ; 89±28 ; 77±7 } cm/s, spectral PS { 77 ; 110 ; 76 } cm/s, EDTO { 10±3 ; 14±8 ; 15±3 } cm/s, spectral ED { 18 ; 13 ; 20 } cm/s, RITO { 0.......87±0.05 ; 0.79±0.21 ; 0.79±0.06 }, and spectral RI { 0.77 ; 0.88 ; 0.73 }. Vector angles are within ±two std of the spectral angle. TO velocity estimates are within ±three std of the spectral estimates. RITO are within ±two std of the spectral estimates. Preliminary data indicates that the TO and spectral...

  9. Kinetic transverse dispersion relation for relativistic magnetized electron-positron plasmas with Maxwell-Jüttner velocity distribution functions

    International Nuclear Information System (INIS)

    López, Rodrigo A.; Moya, Pablo S.; Muñoz, Víctor; Viñas, Adolfo F.; Valdivia, J. Alejandro

    2014-01-01

    We use a kinetic treatment to study the linear transverse dispersion relation for a magnetized isotropic relativistic electron-positron plasma with finite relativistic temperature. The explicit linear dispersion relation for electromagnetic waves propagating along a constant background magnetic field is presented, including an analytical continuation to the whole complex frequency plane for the case of Maxwell-Jüttner velocity distribution functions. This dispersion relation is studied numerically for various temperatures. For left-handed solutions, the system presents two branches, the electromagnetic ordinary mode and the Alfvén mode. In the low frequency regime, the Alfvén branch has two dispersive zones, the normal zone (where ∂ω/∂k > 0) and an anomalous zone (where ∂ω/∂k < 0). We find that in the anomalous zone of the Alfvén branch, the electromagnetic waves are damped, and there is a maximum wave number for which the Alfvén branch is suppressed. We also study the dependence of the Alfvén velocity and effective plasma frequency with the temperature. We complemented the analytical and numerical approaches with relativistic full particle simulations, which consistently agree with the analytical results

  10. Three-dimensional S-wave velocity model of the Bohemian Massif from Bayesian ambient noise tomography

    Science.gov (United States)

    Valentová, Lubica; Gallovič, František; Maierová, Petra

    2017-10-01

    We perform two-step surface wave tomography of phase-velocity dispersion curves obtained by ambient noise cross-correlations in the Bohemian Massif. In the first step, the inter-station dispersion curves were inverted for each period (ranging between 4 and 20 s) separately into phase-velocity maps using 2D adjoint method. In the second step, we perform Bayesian inversion of the set of the phase-velocity maps into an S-wave velocity model. To sample the posterior probability density function, the parallel tempering algorithm is employed providing over 1 million models. From the model samples, not only mean model but also its uncertainty is determined to appraise the reliable features. The model is correlated with known main geologic structures of the Bohemian Massif. The uppermost low-velocity anomalies are in agreement with thick sedimentary basins. In deeper parts (4-20 km), the S-wave velocity anomalies correspond, in general, to main tectonic domains of the Bohemian Massif. The exception is a stable low-velocity body in the middle of the high-velocity Moldanubian domain and high-velocity body resembling a promontory of the Moldanubian into the Teplá-Barrandian domain. The most pronounced (high-velocity) anomaly is located beneath the Eger Rift that is a part of a Tertiary rift system across Europe.

  11. Crustal and uppermantle velocity structure of the northern Korean Peninsula constrained by ambient noise cross-correlations

    Science.gov (United States)

    Lee, S. J.; Rhie, J.; Kim, S.

    2014-12-01

    The seismic velocity structure of the northern Korean Peninsula has not been well known because available seismic data observed inside the region is very rare. Therefore, constructing a one-dimensional (1-D) reference velocity model will be a meaningful first step to understand the detailed velocity structure and also the tectonic evolution of the region. In this study, we use two-year long (2010-2011) ambient noise data recorded by three component broadband seismometers of KIGAM, KMA, F-net, and IRIS networks surrounding the study area. Ambient noise cross-correlations are calculated for station pairs sampling the study area. Multiple filter technique is applied to measure group and phase velocity dispersions of the fundamental mode Rayleigh and Love waves for period ranges between 5 and 70 s, which are sensitive to shear wave velocities in the crust and uppermost mantle. Recently developed inversion method using the Bayesian technique is applied to estimate 1-D models of shear wave velocities and corresponding uncertainties. Combined with the Markov chain Monte Carlo (MCMC) technique, the posterior probability density is evaluated for given data and the prior. Boundaries, velocities, and anisotropy parameters of layers are searched together on the assumption of the layered half-space model. The used method automatically adjusts the number of layers and degree of data fitting by the Bayesian Information Criterion (BIC) estimation and scaling of the data-covariance matrix, respectively. The estimated anisotropic S-wave velocity model in the crust and upper-mantle can help to investigate tectonic processes of the region. For practical use, our velocity model for the Northern Korean Peninsula can be useful to enhance monitoring power of the underground nuclear tests in given area.

  12. Minimum and Terminal Velocities in Fluidization of Particulate Ceramsite at Ambient and Elevated Temperature.

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Trnka, Otakar; Pohořelý, Michael

    2007-01-01

    Roč. 46, 22 (2007) , s. 7260-7266 ISSN 0888-5885 R&D Projects: GA AV ČR(CZ) IAA4072201; GA AV ČR(CZ) IAA400720701 Institutional research plan: CEZ:AV0Z40720504 Keywords : ceramsite * minimum velocities * terminal velocities Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.749, year: 2007

  13. Ambient Noise Tomography of Southern California Images Dipping San Andreas-Parallel Structure and Low-Velocity Salton Trough Mantle

    Science.gov (United States)

    Barak, S.; Klemperer, S. L.; Lawrence, J. F.

    2014-12-01

    Ambient noise tomography (ANT) images the entire crust but does not depend on the spatial and temporal distribution of events. Our ANT high-resolution 3D velocity model of southern California uses 849 broadband stations, vastly more than previous studies, and four years of data, 1997-1998, 2007, and 2011, chosen to include our own broadband Salton Seismic Imaging Project, a 40-station transect across the Salton Trough, as well as other campaign stations in both Mexico and the U.S.A., and permanent stations. Our shear-wave model has 0.05° x 0.05° lateral and 1 km vertical blocks. We used the Harvard Community Velocity Model (CVM-H) as the initial model for the inversion. We show significant differences relative to the CVM-H model, especially in the lower crust and upper mantle. We observe prominent low-velocity anomalies in the upper mantle under the Salton Buttes and Cerro Prieto geothermal fields, indicating high-temperatures and possibly partial-melt. Similar low-velocity zones have been previously observed along the Gulf of California. We also observe vertical to gradually dipping lateral velocity contrasts in the lower crust under the southern part of the San Andreas Fault. The east to northeast dip may represent crustal fabric sheared by movement of the Pacific plate under the North American plate prior to the initiation of transform motion.

  14. An Experimental Measurement on Laminar Burning Velocities and Markstein Length of Iso-Butane-Air Mixtures at Ambient Conditions

    Directory of Open Access Journals (Sweden)

    Yousif Alaeldeen Altag

    2016-01-01

    Full Text Available In the present work, experimental investigation on laminar combustion of iso-butane-air mixtures was conducted in constant volume explosion vessel. The experiments were conducted at wide range of equivalence ratios ranging between Ф = 0.6 and 1.4 and atmospheric pressure of 0.1 MPa and ambient temperature of 303K. Using spherically expanding flame method, flame parameters including stretched, unstretched flame propagation speeds, laminar burning velocities and Markstein length were calculated. For laminar burning velocities the method of error bars of 95% confidence level was applied. In addition, values of Markstein lengths were measured in wide range of equivalence ratios to study the influence of stretch rate on flame instability and burning velocity. It was found that the stretched flame speed and laminar burning velocities increased with equivalence ratios and the peak value was obtained at equivalence ratio of Ф = 1.1. The Markstein length decreased with the increases in equivalence ratios, which indicates that the diffusion thermal flame instability increased at high equivalence ratios in richer mixture side. However, the total deviations in the laminar burning velocities have discrepancies of 1.2-2.9% for all investigated mixtures.

  15. La educación ambiental como tema transversal en el área de conocimiento del medio

    OpenAIRE

    Pérez Rojo, Patricia

    2013-01-01

    La problemática ambiental constituye un tema de interés social a día de hoy, pues es el ser humano el responsable del deterioro de los hábitats y las condiciones ambientales de nuestro planeta. Por ello, es necesario potenciar la educación ambiental en la escuela como medio para transmitir una serie de valores y hábitos que encaminen a las generaciones hacia una forma de vida respetuosa con el medio ambiente consiguiéndose así la formación de una conciencia social basada en el cuidado del en...

  16. Shear velocity model for the westernmost Mediterranean from ambient noise and ballistic finite-frequency Rayleigh wave tomography

    Science.gov (United States)

    Palomeras, I.; Villasenor, A.; Thurner, S.; Levander, A.; Gallart, J.; Harnafi, M.

    2014-12-01

    The westernmost Mediterranean comprises the Iberian Peninsula and Morocco, separated by the Alboran Sea and the Algerian Basin. From north to south this region consists of the Pyrenees, resulting from Iberia-Eurasia collision; the Iberian Massif, which has been undeformed since the end of the Paleozoic; the Central System and Iberian Chain, regions with intracontinental Oligocene-Miocene deformation; the Gibraltar Arc (Betics, Rif and Alboran terranes), resulting from post-Oligocene subduction roll-back; and the Atlas Mountains. We analyzed data from recent broad-band array deployments and permanent stations in the area (IberArray and Siberia arrays, the PICASSO array, the University of Munster array, and the Spanish, Portuguese and Moroccan National Networks) to characterize its lithospheric structure. The combined array of 350 stations has an average interstation spacing of ~60 km. We calculated the Rayleigh waves phase velocities from ambient noise (periods 4 to 40 s) and teleseismic events (periods 20 to 167 s). We inverted the phase velocities to obtain a shear velocity model for the lithosphere to ~200 km depth. Our results correlate well with the surface expression of the main structural units with higher crustal velocity for the Iberian Massif than for the Alpine Iberia and Atlas Mountains. The Gibraltar Arc has lower crustal shear velocities than the regional average at all crustal depths. It also shows an arc shaped anomaly with high upper mantle velocities (>4.6 km/s) at shallow depths (volcanic fields in Iberia and Morocco, indicative of high temperatures at relatively shallow depths, and suggesting that the lithosphere has been removed beneath these areas.

  17. Offshore Rayleigh Group Velocity Observations of the South Island, New Zealand, from Ambient Noise Data

    KAUST Repository

    Yeck, William L.

    2017-02-15

    We present azimuthally anisotropic Rayleigh group velocity models from 8 - 35 s both offshore and onshore of the South Island of New Zealand. We use MOANA (Marine Observations of Anisotropy Near Aotearoa) broadband ocean seismic data in combination with on land data from the New Zealand National Seismography Network (NZNSN) to investigate the seismic structure of the flanks of the Australian-Pacific plate boundary. At 8 s, we observe low offshore group velocities best explained by the influence of the water layer and thick water-laden sediments. At long periods (20-30 s), group velocities are lower on the South Island relative to its offshore flanks, due to thickened crust beneath the island, with the lowest velocities primarily beneath the Southern Alps. Group velocity azimuthal anisotropy fast directions near the Alpine Fault align with the direction of relative plate motion between the Australian and Pacific plates. In the southern portion of the island, fast directions rotate anticlockwise, likely in response to a decrease in dextral shearing away from the plate boundary. Azimuthal anisotropy fast directions align with absolute plate motion offshore on the Pacific plate. Based on the depth sensitivity of our observations, we suggest diffuse deformation occurs throughout the crust. Our observations match trends in previous Pn anisotropy and SKS shear wave splitting observations, and therefore suggest a consistent pattern of distributed deformation throughout the lithosphere.

  18. On the weakly nonlinear, transversal vibrations of a conveyor belt with a low and time-varying velocity

    NARCIS (Netherlands)

    Suweken, G.; van Horssen, W.T.

    2002-01-01

    In this paper the weakly nonlinear, transversal vibrations of a conveyor belt will be considered. The belt is assumed to move with a low and time-varying speed. Using Kirchhoff's approach a single equation of motion will be derived from a coupled system of partial differential equations describing

  19. Ambient noise tomography reveals basalt and sub-basalt velocity structure beneath the Faroe Islands, North Atlantic

    Science.gov (United States)

    Sammarco, Carmelo; Cornwell, David G.; Rawlinson, Nicholas

    2017-11-01

    Ambient noise tomography is applied to seismic data recorded by a portable array of seismographs deployed throughout the Faroe Islands in an effort to illuminate basalt sequences of the North Atlantic Igneous Province, as well as underlying sedimentary layers and Precambrian basement. Rayleigh wave empirical Green's functions between all station pairs are extracted from the data via cross-correlation of long-term recordings, with phase weighted stacking implemented to boost signal-to-noise ratio. Dispersion analysis is applied to extract inter-station group travel-times in the period range 0.5-15 s, followed by inversion for period-dependent group velocity maps. Subsequent inversion for 3-D shear wave velocity reveals the presence of significant lateral heterogeneity (up to 25%) in the crust. Main features of the final model include: (i) a near-surface low velocity layer, interpreted to be the Malinstindur Formation, which comprises subaerial compound lava flows with a weathered upper surface; (ii) a sharp velocity increase at the base of the Malinstindur Formation, which may mark a transition to the underlying Beinisvørð Formation, a thick laterally extensive layer of subaerial basalt sheet lobes; (iii) a low velocity layer at 2.5-7.0 km depth beneath the Beinisvørð Formation, which is consistent with hyaloclastites of the Lopra Formation; (iv) an upper basement layer between depths of 5-9 km and characterized by S wave velocities of approximately 3.2 km/s, consistent with low-grade metamorphosed sedimentary rocks; (v) a high velocity basement, with S wave velocities in excess of 3.6 km/s. This likely reflects the presence of a crystalline mid-lower crust of Archaean continental origin. Compared to previous interpretations of the geological structure beneath the Faroe Islands, our new results point to a more structurally complex and laterally heterogeneous crust, and provide constraints which may help to understand how continental fragments are rifted from the

  20. Transverse and Longitudinal Doppler Effects of the Sunbeam Spectra and Earth-Self Rotation and Orbital Velocities, the Mass of the Sun and Others

    OpenAIRE

    Nam, Sang Boo

    2009-01-01

    The transverse and longitudinal Doppler effects of the sunbeam spectra are shown to result in the earth parameters such as the earth-self rotation and revolution velocities, the earth orbit semi-major axis, the earth orbital angular momentum, the earth axial tilt, the earth orbit eccentricity, the local latitude and the mass of the sun. The sunbeam global positioning scheme is realized, including the earth orbital position. PACS numbers: 91.10.Fc, 95.10.Km, 91.10.Da, 91.10.Jf.

  1. A Trial for Detecting the Temporal Variation in Seismic Velocity Accompanied by a Slow Slip Event using Seismic Interferometry of Ambient Noise

    Science.gov (United States)

    Uemura, Miyuu; Ito, Yoshihiro; Ohta, Kazuaki; Hino, Ryota; Shinohara, Masanao

    2017-04-01

    Seismic interferometry is one of the most effective techniques to detect temporal variations in seismic velocity before or after a large earthquake. Some previous studies have been reported on seismic velocity reduction due to the occurrence of large earthquakes (e.g., Wegler et al., 2009; Yamada et al., 2010) as well as preceding them (e.g., Lockner et al., 1977; Yoshimitsu et al., 2009). However, there have only been a few studies thus far which attempt to detect seismic velocity changes associated with slow slip events (SSEs). In this study, we focus on applying seismic interferometry to ambient noise data from ocean bottom seismometers (OBSs) deployed near a subduction zone. Between the end of January 2011 and the largest foreshock occurring on March 9th that precedes the March 11, 2011 Tohoku-Oki earthquake, SSEs and low-frequency tremors were detected offshore Miyagi Prefecture (Ito et al., 2013, 2015; Katakami et al., 2016). We applied our seismic interferometry analysis using ambient noise to recordings from 17 OBS stations that were installed in the vicinity of the 2011 Tohoku-Oki earthquake source region, and only considered the recordings from before that major earthquake. All the OBSs are short-period seismometers with three components which have an eigenfrequency of 4.5 Hz. These OBSs were deployed offshore Miyagi Prefecture between November 2010 and April 2011. Before proceeding with the seismic interferometry analysis, we needed to estimate the two horizontal components of the original deployment orientation for 13 OBSs in (we could not estimate them for 4 OBSs). To obtain the OBS orientation, we used particle orbits of some direct P waves from selected tectonic earthquakes, in order to extract one vertical and two horizontal components. Then, the seismic interferometry analysis consisted of the following steps. First, we applied a band-pass filter of 0.25-2.0 Hz and one-bit technique to the ambient noise signal. Second, we calculated auto

  2. Dielectric waveguide with transverse index variation that support a zero group velocity mode at a non-zero longitudinal wavevector

    Science.gov (United States)

    Ibanescu, Mihai; Joannopoious, John D.; Fink, Yoel; Johnson, Steven G.; Fan, Shanhui

    2005-06-21

    Optical components including a laser based on a dielectric waveguide extending along a waveguide axis and having a refractive index cross-section perpendicular to the waveguide axis, the refractive index cross-section supporting an electromagnetic mode having a zero group velocity for a non-zero wavevector along the waveguide axis.

  3. Multi-component pre-stack time-imaging and migration-based velocity analysis in transversely isotropic media; Imagerie sismique multicomposante et analyse de vitesse de migration en milieu transverse isotrope

    Energy Technology Data Exchange (ETDEWEB)

    Gerea, C.V.

    2001-06-01

    Complementary to the recording of compressional (P-) waves, the observation of P-S converted waves has recently been receiving specific attention. This is mainly due to their tremendous potential as a tool for fracture and lithology characterization, imaging sediments in gas saturated rocks, and imaging shallow sediments with higher resolution than conventional P-P data. In a conventional marine seismic survey, we cannot record P-to-S converted-wave energy since the fluids cannot support shear-wave strain. Thus, to capture the converted-wave energy, we need to record it at the water-bottom casing an ocean-bottom cable (OBC). The S-waves recorded at the seabed are mainly converted from P to S (i.e., PS-waves or C-waves) at the subsurface reflectors. The most accurate way to image seismic data is pre-stack depth migration. In this thesis, I develop a numerically efficient 2.5-D true-amplitude elastic Kirchhoff pre-stack migration algorithm designed to handle OBC data gathered along a single line. All the kinematic and dynamic elastic Green's functions required in the computation of true-amplitude weight term of Kirchhoff summation, are based on the non-hyperbolic explicit approximations of P- and SV-wave travel-times in layered transversely isotropic (VTI) media. Hence, this elastic imaging algorithm is very well-suited for migration-based velocity analysis techniques, for which fast, robust and iterative pre-stack migration is desired. In this thesis, I approach also the topic of anisotropic velocity model building for elastic pre-stack time-imaging. and propose an original methodology for joint PP-PS migration-based velocity analysis (MVA) in layered VTI anisotropic media. Tests on elastic synthetic and real OBC seismic data ascertain the validity of the pre-stack migration algorithm and velocity analysis methodology. (author)

  4. Shallow velocity structure above the Socorro Magma Body from ambient noise tomography using the large-N Sevilleta array, central Rio Grande Rift, New Mexico

    Science.gov (United States)

    Worthington, L. L.; Ranasinghe, N. R.; Schmandt, B.; Jiang, C.; Finlay, T. S.; Bilek, S. L.; Aster, R. C.

    2017-12-01

    The Socorro Magma Body (SMB) is one of the largest recognized active mid-crustal magma intrusions globally. Inflation of the SMB drives sporadically seismogenic uplift at rates of up to of few millimeters per year. We examine the upper crustal structure of the northern section of the SMB region using ambient noise seismic data collected from the Sevilleta Array and New Mexico Tech (NMT) seismic network to constrain basin structure and identify possible upper crustal heterogeneities caused by heat flow and/or fluid or magma migration to shallower depths. The Sevilleta Array comprised 801 vertical-component Nodal seismic stations with 10-Hz seismometers deployed within the Sevilleta National Wildlife Refuge in the central Rio Grande rift north of Socorro, New Mexico, for a period of 12 days during February 2015. Five short period seismic stations from the NMT network located south of the Sevilleta array are also used to improve the raypath coverage outside the Sevilleta array. Inter-station ambient noise cross-correlations were computed from all available 20-minute time windows and stacked to obtain estimates of the vertical component Green's function. Clear fundamental mode Rayleigh wave energy is observed from 3 to 6 s period. Beamforming indicates prominent noise sources from the southwest, near Baja California, and the southeast, in the Gulf of Mexico. The frequency-time analysis method was implemented to measure fundamental mode Rayleigh wave phase velocities and the resulting inter-station travel times were inverted to obtain 2-D phase velocity maps. One-dimensional sensitivity kernels indicate that the Rayleigh wave phase velocity maps are sensitive to a depth interval of 1 to 8 km, depending on wave period. The maps show (up to 40%) variations in phase velocity within the Sevilleta Array, with the largest variations found for periods of 5-6 seconds. Holocene to upper Pleistocene, alluvial sediments found in the Socorro Basin consistently show lower phase

  5. GSpecDisp: A matlab GUI package for phase-velocity dispersion measurements from ambient-noise correlations

    Science.gov (United States)

    Sadeghisorkhani, Hamzeh; Gudmundsson, Ólafur; Tryggvason, Ari

    2018-01-01

    We present a graphical user interface (GUI) package to facilitate phase-velocity dispersion measurements of surface waves in noise-correlation traces. The package, called GSpecDisp, provides an interactive environment for the measurements and presentation of the results. The selection of a dispersion curve can be done automatically or manually within the package. The data are time-domain cross-correlations in SAC format, but GSpecDisp measures phase velocity in the spectral domain. Two types of phase-velocity dispersion measurements can be carried out with GSpecDisp; (1) average velocity of a region, and (2) single-pair phase velocity. Both measurements are done by matching the real part of the cross-correlation spectrum with the appropriate Bessel function. Advantages of these two types of measurements are that no prior knowledge about surface-wave dispersion in the region is needed, and that phase velocity can be measured up to that period for which the inter-station distance corresponds to one wavelength. GSpecDisp can measure the phase velocity of Rayleigh and Love waves from all possible components of the noise correlation tensor. First, we briefly present the theory behind the methods that are used, and then describe different modules of the package. Finally, we validate the developed algorithms by applying them to synthetic and real data, and by comparison with other methods. The source code of GSpecDisp can be downloaded from: https://github.com/Hamzeh-Sadeghi/GSpecDisp

  6. Spatio-temporal changes in seismic velocity associated with the 2000 activity of Miyakejima volcano as inferred from cross-correlation analyses of ambient noise

    Science.gov (United States)

    Anggono, Titi; Nishimura, Takeshi; Sato, Haruo; Ueda, Hideki; Ukawa, Motoo

    2012-12-01

    Miyakejima volcano, Japan, showed strong and interesting volcanic activities in 2000 with the occurrence of dike intrusions, caldera formation and a large amount of gas emission. To understand temporal changes of the volcanic structure associated with this activity, we apply ambient noise correlation analyses to the seismic records of five seismic stations at Miyakejima volcano from July 1999 to December 2002. We calculate cross-correlation functions (CCFs) for eight available station pairs at frequency bands of 0.4-0.8 Hz and 0.8-1.6 Hz, and retrieve the Rayleigh waves propagating with a group velocity of about 1.0 km/s. Comparing CCFs obtained for each day with the reference CCFs that are calculated from a few months of data, we estimate seismic velocity changes before and after the 2000 activity. Results at the two frequency bands show seismic velocity increase and decrease. Shallow structure at the volcanic edifice on the flanks experienced a seismic velocity increase up to 3.3%. On the other hand, the regions located close to the collapsed caldera show a seismic velocity decrease down to 2.3%. To understand the mechanisms that may introduce these seismic velocity increase and decrease, we examine several possible mechanisms of the velocity changes: stress changes due to volcanic pressure sources and caldera formation, and topographic changes. By using the deflation sources previously determined from GPS data, we calculate the stresses at depths of 0 km and 1 km at the volcano. The results suggest that the seismic velocity increases observed at seismic paths on the volcanic flank are explained by the compression caused by the deflation sources associated with magma activity in 2000. Stress sensitivities of the seismic velocity changes are estimated to be 1.5 × 10- 2 to 2.2 × 10- 2 MPa- 1 and 4.6 × 10- 3 to 2.4 × 10- 2 MPa- 1 at frequency bands of 0.4-0.8 Hz and 0.8-1.6 Hz, respectively, which are in the range of the previously reported results. Our three

  7. Crustal and upper mantle shear velocities of Iberia, the Alboran Sea, and North Africa from ambient noise and ballistic finite-frequency Rayleigh wave tomography

    Science.gov (United States)

    Palomeras, I.; Villasenor, A.; Thurner, S.; Levander, A.; Gallart, J.; mimoun, H.

    2013-12-01

    The complex Mesozoic-Cenozoic Alpine deformation in the western Mediterranean extends from the Pyrenees in northern Spain to the Atlas Mountains in southern Morocco. The Iberian plate was accreted to the European plate in late Cretaceous, resulting in the formation of the Pyrenees. Cenozoic African-European convergence resulted in subduction of the Tethys oceanic plate beneath Europe. Rapid Oligocene slab rollback from eastern Iberia spread eastward and southward, with the trench breaking into three segments by the time it reached the African coast. One trench segment moved southwestward and westward creating the Alboran Sea, floored by highly extended continental crust, and building the encircling Betics Rif mountains comprising the Gibraltar arc, and the Atlas mountains, which formed as the inversion of a Jurassic rift. A number of recent experiments have instrumented this region with broad-band arrays (the US PICASSO array, Spanish IberArray and Siberia arrays, the University of Munster array), which, including the Spanish, Portuguese, and Moroccan permanent networks, provide a combined array of 350 stations having an average interstation spacing of ~60 km. Taking advantage of this dense deployment, we have calculated the Rayleigh waves phase velocities from ambient noise for short periods (4 s to 40 s) and teleseismic events for longer periods (20 s to 167 s). Approximately 50,000 stations pairs were used to measure the phase velocity from ambient noise and more than 160 teleseismic events to measure phase velocity for longer periods. The inversion of the phase velocity dispersion curves provides a 3D shear velocity for the crust and uppermost mantle. Our results show differences between the various tectonic regions that extend to upper mantle depths (~200 km). In Iberia we obtain, on average, higher upper mantle shear velocities in the western Variscan region than in the younger eastern part. We map high upper mantle velocities (>4.6 km/s) beneath the

  8. Postseismic velocity changes following the 2010 Mw 7.1 Darfield earthquake, New Zealand, revealed by ambient seismic field analysis

    Science.gov (United States)

    Heckels, R. E. G.; Savage, M. K.; Townend, J.

    2018-01-01

    Quantifying seismic velocity changes following large earthquakes can provide insights into fault healing and reloading processes. This study presents temporal velocity changes detected following the September 2010 Mw 7.1 Darfield event in Canterbury, New Zealand. We use continuous waveform data from several temporary seismic networks lying on and surrounding the Greendale Fault, with a maximum inter-station distance of 156 km. Nine-component, day-long Green's functions were computed for frequencies between 0.1 and 1.0 Hz for continuous seismic records from immediately after the 4 September 2010 earthquake until 10 January 2011. Using the moving-window cross-spectral method seismic velocity changes were calculated. Over the study period, an increase in seismic velocity of 0.14 % ± 0.04 % was determined near the Greendale Fault, providing a new constraint on postseismic relaxation rates in the region. A depth analysis further showed that velocity changes were confined to the uppermost 5 km of the subsurface. We attribute the observed changes to postseismic relaxation via crack-healing of the Greendale Fault and throughout the surrounding region.

  9. Joint inversion of teleseismic P waveforms and surface-wave group velocities from ambient seismic noise in the Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Růžek, Bohuslav; Plomerová, Jaroslava; Babuška, Vladislav

    2012-01-01

    Roč. 56, č. 1 (2012), s. 107-140 ISSN 0039-3169 R&D Projects: GA ČR GA205/07/1088; GA AV ČR IAA300120709; GA MŠk LM2010008 Institutional research plan: CEZ:AV0Z30120515 Keywords : receiver function * seismic noise * joint inversion * Bohemian Massif * velocity structure Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.975, year: 2012

  10. Crustal and upper mantle S-wave velocity structures across the Taiwan Strait from ambient seismic noise and teleseismic Rayleigh wave analyses

    Science.gov (United States)

    Huang, Y.; Yao, H.; Wu, F. T.; Liang, W.; Huang, B.; Lin, C.; Wen, K.

    2013-12-01

    Although orogeny seems to have stopped in western Taiwan large and small earthquakes do occur in the Taiwan Strait. Limited studies have focused on this region before and were barely within reach for comprehensive projects like TAICRUST and TAIGER for logistical reasons; thus, the overall crustal structures of the Taiwan Strait remain unknown. Time domain empirical Green's function (TDEGF) from ambient seismic noise to determine crustal velocity structure allows us to study an area using station pairs on its periphery. This research aims to resolve 1-D average crustal and upper mantle S-wave velocity (Vs) structures alone paths of several broadband station-pairs across the Taiwan Strait; 5-120 s Rayleigh wave phase velocity dispersion data derived by combining TDEGF and traditional surface wave two-station method (TS). The average Vs structures show significant differences in the upper 15 km as expected. In general, the highest Vs are observed in the coastal area of Mainland China and the lowest Vs appear along the southwest offshore of the Taiwan Island; they differ by about 0.6-1.1 km/s. For different parts of the Strait, the Vs are lower in the middle by about 0.1-0.2 km/s relative to those in the northern and southern parts. The overall crustal thickness is approximately 30 km, much thinner and less variable than under the Taiwan Island.

  11. A model for the Lin-Shu type density-wave structure of our Galaxy: Line-of-sight and transverse-longitudinal velocities of 242 optically visible open clusters

    Science.gov (United States)

    Griv, E.; Jiang, I.-G.

    2015-02-01

    In this paper, the fourth in a series, we examine again one of the implications of the Lin-Shu density-wave theory, specifically, the noncircular systematic motion of the Galactic objects. Our previous investigation is extended by analyzing simultaneously both the line-of-sight and transversal velocities of a sample of open clusters for which velocities, distances and ages are available. The ordinary equations of the Oort-Lindblad theory of galactic differential rotation are used. The minor effects caused by the two-dimensional tightly-wound density waves are also taken into account. The published data of 242 currently known optically visible clusters having distances rsight and transversal along the Galactic longitude velocities are nearly equal. We argue that the resemblance of these Galactic wave structures is so remarkable that no doubt is felt as to the theory's truth with respect to these data. The results obtained allow us to conclude that several low-m trailing density-wave patterns with different number of spiral arms m (say, m=1, 2, 3, and 4), pitch angles (about 5o, 8o, 11o, and 14o, respectively) and amplitudes of the perturbed gravitational potential may coexist in the Galaxy. The latter suggests the asymmetric multiarm, not well-organized (``flocculent'') spiral structure of the system. In memory of Professors Alexei M. Fridman (1940-2010) and Chi Yuan (1937-2008)

  12. A Generalized Version of a Low Velocity Impact between a Rigid Sphere and a Transversely Isotropic Strain-Hardening Plate Supported by a Rigid Substrate Using the Concept of Noninteger Derivatives

    Directory of Open Access Journals (Sweden)

    Abdon Atangana

    2013-01-01

    Full Text Available A low velocity impact between a rigid sphere and transversely isotropic strain-hardening plate supported by a rigid substrate is generalized to the concept of noninteger derivatives order. A brief history of fractional derivatives order is presented. The fractional derivatives order adopted is in Caputo sense. The new equation is solved via the analytical technique, the Homotopy decomposition method (HDM. The technique is described and the numerical simulations are presented. Since it is very important to accurately predict the contact force and its time history, the three stages of the indentation process, including (1 the elastic indentation, (2 the plastic indentation, and (3 the elastic unloading stages, are investigated.

  13. Transverse correlation: An efficient transverse flow estimator - initial results

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund; Henze, Lasse; Kortbek, Jacob

    2008-01-01

    Color flow mapping has become an important clinical tool, for diagnosing a wide range of vascular diseases. Only the velocity component along the ultrasonic beam is estimated, so to find the actual blood velocity, the beam to flow angle has to be known. Because of the unpredictable nature...... for estimating the transverse velocity component. The method measures the transverse velocity component by estimating the transit time of the blood between two parallel lines beamformed in receive. The method has been investigated using simulations performed with Field II. Using 15 emissions per estimate...

  14. Crustal and uppermost mantle S-wave velocity below the East European Craton in northern Poland from the inversion of ambient-noise records

    Science.gov (United States)

    Lepore, Simone; Polkowski, Marcin; Grad, Marek

    2018-02-01

    The P-wave velocities (V p) within the East European Craton in Poland are well known through several seismic experiments which permitted to build a high-resolution 3D model down to 60 km depth. However, these seismic data do not provide sufficient information about the S-wave velocities (V s). For this reason, this paper presents the values of lithospheric V s and P-wave-to-S-wave velocity ratios (V p/V s) calculated from the ambient noise recorded during 2014 at "13 BB star" seismic array (13 stations, 78 midpoints) located in northern Poland. The 3D V p model in the area of the array consists of six sedimentary layers having total thickness within 3-7 km and V p in the range 1.85.3 km/s, a three-layer crystalline crust of total thickness 40 km and V p within 6.15-7.15 km/s, and the uppermost mantle, where V p is about 8.25 km/s. The V s and V p/V s values are calculated by the inversion of the surface-wave dispersion curves extracted from the noise cross correlation between all the station pairs. Due to the strong velocity differences among the layers, several modes are recognized in the 0.021 Hz frequency band: therefore, multimodal Monte Carlo inversions are applied. The calculated V s and V p/V s values in the sedimentary cover range within 0.992.66 km/s and 1.751.97 as expected. In the upper crust, the V s value (3.48 ± 0.10 km/s) is very low compared to the starting value of 3.75 ± 0.10 km/s. Consequently, the V p/V s value is very large (1.81 ± 0.03). To explain that the calculated values are compared with the ones for other old cratonic areas.

  15. Can we trace the eastern Gondwanan margin in Australia? New perspectives from transdimensional inversion of ambient noise for 3D shear velocity structure

    Science.gov (United States)

    Pilia, S.; Rawlinson, N.; Direen, N. G.

    2013-12-01

    Although the notion of Rodinia is quite well accepted in the geoscience community, the location and nature of the eastern continental margin of the Gondwana fragment in Australia is still vague and remains one of the most hotly debated topics in Australian geology. Moreover, most post-Rodinian reconstructions models choose not to tackle the ';Tasmanian challenge', and focus only on the tectonic evolution of mainland southeast Australia, thereby conveniently ignoring the wider tectonic implications of Tasmania's complex geological history. One of the chief limitations of the tectonic reconstructions in this region is a lack of information on Paleozoic (possibly Proterozoic) basement structures. Vast Mesozoic-Cainozoic sedimentary and volcanic cover sequences obscure older outcrops and limit the power of direct observational techniques. In response to these challenges, our effort is focused on ambient seismic noise for imaging 3D crustal shear velocity structure using surface waves, which is capable of illuminating basement structure beneath younger cover. The data used in this study is sourced from the WOMBAT transportable seismic array, which is compounded by around 650 stations spanning the majority of southeastern Australia, including Tasmania and several islands in Bass Strait. To produce the highest quality Green's functions, careful processing of the data has been performed, after which group velocity dispersion measurements have been carried out using a frequency-time analysis method on the symmetric component of the empirical Green's functions (EGFs). Group dispersion measurements from the EGFs have been inverted using a novel hierarchical, transdimensional, Bayesian algorithm to obtain Rayleigh-wave group velocity maps at different periods from 2 to 30 s. The new approach has several advantages in that the number and distribution of model parameters are implicitly controlled by the data, in which the noise is treated as unknown in the inversion. This

  16. Physics-based formula representations of high-latitude ionospheric outflows: H+ and O+ densities, flow velocities, and temperatures versus soft electron precipitation, wave-driven transverse heating, and solar zenith angle effects

    Science.gov (United States)

    Horwitz, J. L.; Zeng, W.

    2009-01-01

    Extensive systematic dynamic fluid kinetic (DyFK) model simulations are conducted to obtain advanced simulation-based formula representations of ionospheric outflow parameters, for possible use by global magnetospheric modelers. Under F10.7 levels of 142, corresponding to solar medium conditions, we obtain the H+ and O+ outflow densities, flow velocities, and perpendicular and parallel temperatures versus energy fluxes and characteristic energies of soft electron precipitation, wave spectral densities of ion transverse wave heating, and F region level solar zenith angle in the high-latitude auroral region. From the results of hundreds of DyFK simulations of auroral outflows for ranges of each of these driving agents, we depict the H+ and O+ outflow density and flow velocity parameters at 3 R E altitude at the ends of these 2-h simulation runs in spectrogram form versus various pairs of these influencing parameters. We further approximate these results by various distilled formula representations for the O+ and H+ outflow velocities, densities, and temperatures at 3 R E altitude, as functions of the above indicated four ``driver'' parameters. These formula representations provide insight into the physics of these driven outflows, and may provide a convenient set of tools to set the boundary conditions for ionospheric plasma sources in global magnetospheric simulations.

  17. Spatio-temporal changes of seismic velocity at Miyakejima volcano associated with the 2000 eruption based on the cross-correlation analyses of ambient seismic noise records

    Science.gov (United States)

    Anggono, T.; Nishimura, T.; Sato, H.; Ueda, H.; Ukawa, M.

    2009-12-01

    Miyakejima Island is located about 170 km to the south of Tokyo, Japan. The 2000 activity started with a small submarine eruption in late June 2000, which accompanied earthquake swarms. A caldera was formed from July to August and had a diameter of about 1.6 km. Since then the volcanic gas was effused and the activity continued for more than four years. We analyze the ambient seismic noise recorded from July 1999 to December 2002 at four NIED seismic stations to study the volcano structure behavior associated with this volcanic activity. The continuous records are sampled at frequency of 100 Hz with an A/D resolution of 16-bit. We apply cross-correlation analyses to the continuous records of vertical component of short period seismometers (1 s) for every possible pair of stations. Before calculating the cross-correlation function (CCF), we bandpass filter the data using three-order Butterworth filter with frequency bands 0.4 - 0.8 Hz and 0.8 - 1.6 Hz. We calculate the CCFs with 60 s window length, and then stack for one day data. The observed CCFs are symmetric at both negative and positive lag times; this means that the distribution of noise sources is quite homogeneous surrounding the Miyakejima Island. We define a reference Green’s function (RGF) for every station pair by stacking the CCFs for about 10 months in 2002 during which no major instrumental errors were found. Once RGF is defined for each station pair, we calculate the cross-correlation coefficient between the RGF and the CCFs of each day, and select “good” CCFs that have cross-correlation coefficient larger than 0.7 and lag time smaller than +/- 0.5 s. We pick travel times of the maximum amplitude of the wave packets at positive and negative lag times, which correspond to the travel time of Rayleigh waves between two stations, from the RGF and the “good” CCFs of each day. To estimate the changes in the medium, we calculate the average travel time difference for periods July 1999 - May 2000

  18. Transversity 2005

    Science.gov (United States)

    Barone, Vincenzo; Ratcliffe, Philip G.

    Introduction. Purpose and status of the Italian Transversity Project / F. Bradamante -- Opening lecture. Transversity / M. Anselmino -- Experimental lectures. Azimuthal single-spin asymmetries from polarized and unpolarized hydrogen targets at HERMES / G. Schnell (for the HERMES Collaboration). Collins and Sivers asymmetries on the deuteron from COMPASS data / I. Horn (for the COMPASS Collaboration). First measurement of interference fragmentation on a transversely polarized hydrogen target / P. B. van der Nat (for the HERMES Collaboration). Two-hadron asymmetries at the COMPASS experiment / A. Mielech (for the COMPASS Collaboration). Measurements of chiral-odd fragmentation functions at Belle / R. Seidl ... [et al.]. Lambda asymmetries / A. Ferrero (for the COMPASS Collaboration). Transverse spin at PHENIX: results and prospects / C. Aidala (for the PHENIX Collaboration). Transverse spin and RHIC / L. Bland. Studies of transverse spin effects at JLab / H. Avakian ... [et al.] (for the CLAS Collaboration). Neutron transversity at Jefferson Lab / J. P. Chen ... [et al.] (for the Jefferson Lab Hall A Collaboration). PAX: polarized antiproton experiments / M. Contalbrigo. Single and double spin N-N interactions at GSI / M. Maggiora (for the ASSIA Collaboration). Spin filtering in storage rings / N. N. Nikolaev & F. F. Pavlov -- Theory lectures. Single-spin asymmetries and transversity in QCD / S. J. Brodsky. The relativistic hydrogen atom: a theoretical laboratory for structure functions / X. Artru & K. Benhizia. GPD's and SSA's / M. Burkardt. Time reversal odd distribution functions in chiral models / A. Drago. Soffer bound and transverse spin densities from lattice QCD / M. Diehl ... [et al.]. Single-spin asymmetries and Qiu-Sterman effect(s) / A. Bacchetta. Sivers function: SIDIS data, fits and predictions / M. Anselmino ... [et al.]. Twist-3 effects in semi-inclusive deep inelastic scattering / M. Schlegel, K. Goeke & A. Metz. Quark and gluon Sivers functions / I

  19. [Transversal problems].

    Science.gov (United States)

    Mendoza Mendoza, A; Solano Reina, E

    1990-04-01

    In this worn we introduce the alterations of the occlusion in the horizontal level or transversal problems, in which lateral crossed bites appear, either with or without a deviation of the medium line, underlying its differential diagnostic and guide lines treatment through several different clinic cases.

  20. Transverse myelitis

    International Nuclear Information System (INIS)

    Black, M.J.; Motaghedi, B.; Robitaille, Y.

    1980-01-01

    Transverse myelitis is a known complication of radiation treatment for carcinoma of the heat and neck. In a five year period, 1970 to 1975, 120 patients with head and neck cancer received radiation as part of their treatment in this hospital. A review of the records of these patients showed only two cases of myelitis, an incidence of about 2%. This paper reviews the clinical syndrome; treatment and preventive measures are discussed and a survey of the literature is presented

  1. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  2. Directional Transverse Oscillation Vector Flow Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2017-01-01

    A method for estimating vector velocities using transverse oscillation (TO) combined with directional beamforming is presented. In Directional Transverse Oscillation (DTO) a normal focused field is emitted and the received signals are beamformed in the lateral direction transverse to the ultrasound...... beam to increase the amount of data for vector velocity estimation. The approach is self-calibrating as the lateral oscillation period is estimated from the directional signal through a Fourier transform to yield quantitative velocity results over a large range of depths. The approach was extensively...

  3. Efeito das dimensões da seção transversal e da frequência do transdutor na velocidade de propagação de ondas de ultra-som na madeira Effect of the transversal section dimensions and transducer frequency on ultrasound wave propagation velocity in wood

    Directory of Open Access Journals (Sweden)

    Alex Julio Trinca

    2009-02-01

    Full Text Available Diversas pesquisas vêm sendo realizadas com o uso da velocidade de propagação de ondas de ultra-som como parâmetro para estimar propriedades mecânicas da madeira. Tendo em vista que essa velocidade pode ser influenciada pela forma da peça ensaiada, bem como pela frequência do transdutor utilizado no ensaio, conhecer essas fontes de influência é fator importante para a obtenção de resultados confiáveis. Durante estudo mais amplo sobre a influência da dimensão do corpo-de-prova em ensaios destrutivos de compressão paralela às fibras, os corpos-de-prova de 0,03 x 0,03 x 0,09 m e de 0,05 x 0,05 x 0,15 m foram também utilizados para avaliar a variação da velocidade de propagação de ondas de ultrassom em razão da dimensão da peça ensaiada. Para a avaliação da influência da frequência, os ensaios foram realizados com transdutores de onda longitudinal (compressão de 25 kHz, 45 kHz, 80 kHz, 100 kHz, 500 kHz e 1 MHz, em 119 corpos-de-prova de Pinus elliottii e 244 de Eucalyptus grandis. Os resultados indicaram que, em ambas as espécies, a seção transversal exerceu influência na propagação da onda de ultrassom e que a velocidade longitudinal foi fortemente afetada pela frequência do transdutor para frequências abaixo de 500 kHz, corroborando a importância de sempre se adotarem, nos ensaios, relações de comprimento de percurso/comprimento de onda superiores a 3,0.Several works use the ultrasound wave propagation velocity as the main parameter to determine the mechanical properties of wood. Since this velocity can be influenced by the specimen's dimension or by the transducer's frequency, this influence must be known to obtain reliable results. During research on the influence of specimen dimension on destructive testing of the compression parallel to the grain, 0.03 x 0.03 x 0.09 m and 0.05 x 0.05 x 0.15 m specimens were tested to evaluate the variation in wave propagation velocity as a function of specimen dimension

  4. Transverse feedback

    CERN Document Server

    Cornelis, K; Sladen, Jonathan P H; CERN. Geneva. SPS and LEP Division

    1997-01-01

    The aim of these MD's was to set up the transverse feedback for damping in both planes, and to test the charge normalization and gain compensation. The latter is intended to reduce the gain of the feedback for small oscillations in order to improve compatibility with the Q loop. All work was done with 2 x 4 bunches, family A. In the first two MD's the feedback was set up for damping in both planes with charge normalization. In the third, gain compensation was commissioned in the vertical plane with Qv' set to -2. It was found either to increase the level of the m = 0 mode or to leave it unchanged. Under these conditions 6mA total current was accumulated.

  5. Transverse damper

    CERN Document Server

    Höfle, W

    2012-01-01

    Plans for the operation of the transverse damper in 2012 at bunch spacings of 50 ns and 25 ns and at increased collision energy will be reviewed. The increased energy and the experience that will be gained at 25 ns are very important to define any upgrades that may be necessary for the high luminosity operation at 7 TeV after LS1. This means that the available parameter space must be probed in 2012 which in particular includes a higher feedback gain in the ramp and with colliding beams. Limits for the feedback gain for the current system will be outlined. The potential benefits of running with higher feedback gain for a better emittance preservation will be stressed and weighed against the operational difficulties and the potential impact of noise in the damper system. A plan for re-commissiong at 50 ns and 25 ns for operation at 4 TeV will be outlined.

  6. Exposição ao fumo ambiental do tabaco em Chaves depois da implementação da Lei 37/2007. Estudo transversal em 2 centros de saúde

    Directory of Open Access Journals (Sweden)

    C. Paradela

    2013-07-01

    Full Text Available Resumo: Introdução: O fumo ambiental do tabaco (FAT é atualmente o principal poluente do meio interior e responsável por uma elevada morbilidade e mortalidade. Uma restrição parcial foi introduzida em Portugal, em 2008, a Lei 37/2007, para tentar controlar, definir e regular ambientes livres de fumo. Objetivo: Avaliar a exposição e a perceção do impacto da Lei 37/2007 sobre a exposição ao FAT em adultos atendidos em 2 centros de saúde em Chaves (Portugal. Método: Um estudo transversal sobre o consumo de tabaco e a exposição ao FAT foi realizado em Chaves (norte de Portugal entre novembro de 2009 e fevereiro de 2010. Todos os pacientes, com mais de 17 anos, atendidos em qualquer dos 2 Centros de Saúde de Chaves. A recolha de dados dos pacientes foi feita em uma base aleatória, abrangendo todos os dias da semana. Foi efetuada uma entrevista cara-a-cara e foi medido o monóxido de carbono exalado. Prevalências e médias foram analisadas para um intervalo de confiança de 95%. Resultados: Dos centos oitenta e sete pacientes participantes na pesquisa, 56% eram do sexo masculino e apresentavam uma média de idades de 54 anos. A prevalência de fumadores foi de 24%, significativamente maior nos homens (31 vs. 17%. 46,2% referiram estar expostos ao fumo de tabaco em todos os lugares estudados (53% nos homens vs. 40% nas mulheres. Os fumadores declararam estar mais expostos ao FAT em relação aos não fumadores. 16,2% da população estavam expostos em casa, 14% no trabalho e 33% nos lugares de lazer. A maior diminuição da perceção de exposição passiva encontrou-se nos restaurantes (95%. Nas discotecas, 68% dos participantes afirmaram que a exposição se manteve inalterada. Conclusão: A lei antitabaco pretende oferecer proteção contra o fumo do tabaco em vários espaços públicos fechados. No entanto, uma percentagem significativa da população permanece exposta. Este estudo destaca os perigos de uma proibição parcial

  7. Experimental investigation of transverse flow estimation using transverse oscillation

    DEFF Research Database (Denmark)

    Udesen, Jesper; Jensen, Jørgen Arendt

    2003-01-01

    Conventional ultrasound scanners can only display the blood velocity component parallel to the ultrasound beam. Introducing a laterally oscillating field gives signals from which the transverse velocity component can be estimated using 2:1 parallel receive beamformers. To yield the performance...... perpendicular to the ultrasound beam. The velocity profile of the blood is parabolic, and the speed of the blood in the center of the vessel is 1.1 m/s. An extended autocorrelation algorithm is used for velocity estimation for 310 trials, each containing 32 beamformed signals. The velocity can be estimated.......0% and the relative mean standard deviation is found to be 9.8%. With the Compuflow 1000 programmable flow pump a color flow mode image is produced of the experimental setup for a parabolic flow. Also the flow of the human femoralis is reproduced and it is found that the characteristics of the flow can be estimated....

  8. Investigation of Transverse Oscillation Method

    DEFF Research Database (Denmark)

    Udesen, Jesper; Jensen, Jørgen Arendt

    2006-01-01

    Conventional ultrasound scanners can only display the axial component of the blood velocity vector, which is a significant limitation when vessels nearly parallel to the skin surface are scanned. The transverse oscillation method (TO) overcomes this limitation by introducing a transverse oscillat......Conventional ultrasound scanners can only display the axial component of the blood velocity vector, which is a significant limitation when vessels nearly parallel to the skin surface are scanned. The transverse oscillation method (TO) overcomes this limitation by introducing a transverse...... II. A virtual linear array transducer with center frequency 7 MHz and 128 active elements is created, and a virtual blood vessel of radius 6.4 mm is simulated. The performance of the TO method is found around an initial point in the parameter space. The parameters varied are: flow angle, transmit...... focus depth, receive apodization, pulse length, transverse wave length, number of emissions, signal to noise ratio, and type of echo canceling filter used. Using the experimental scanner RASMUS, the performance of the TO method is evaluated. An experimental flowrig is used to create laminar parabolic...

  9. Innovación didáctica: la gestión ambiental como eje transversal en educación primaria y secundaria Teaching innovation: environmental management as a central focus in primary and secondary

    Directory of Open Access Journals (Sweden)

    Álvaro Fernández González

    2012-11-01

    Full Text Available El objetivo de este proyecto es brindar, a docentes, herramientas teóricas y prácticas relevantes, con actividades curriculares o extracurriculares de gestión ambiental en primaria, secundaria o educación diversificada, a fin de que puedan desarrollar y evaluar propuestas sistemáticas de innovación didáctica en este campo. Se procura crear las condiciones para que centros educativos públicos del sur de Costa Rica incorporen un componente que estimule el desarrollo de destrezas y habilidades para la participación ciudadana en la gestión ambiental a escala local (cantonal o distrital. El proyecto inició con la Dirección Regional de Educación de Pérez Zeledón y, en el 2012, el proyecto se extendió a la Dirección Regional de Educación Grande de Térraba (la cual abarca los cantones de Buenos Aires de Puntarenas y Osa por solicitud expresa de esta dirección regional. Se aplicó un enfoque de extensión docente y educación continua para fortalecer el currículo de centros educativos con innovaciones didácticas en el tema transversal de cultura ambiental para el desarrollo sostenible. La estrategia fundamental del proyecto se ha centrado en el desarrollo de un curso modular de “Innovación educativa de la gestión integrada de la salud y el ambiente” (IE- GISA, en cuyo marco los docentes participantes diseñan y ejecutan, en sus centros educativos, acciones curriculares y extracurriculares en este campo, apoyados por especialistas de la zona. Los docentes participantes son convocados por las autoridades competentes del Ministerio de Educación Pública, de manera que están autorizados para dedicar tiempo laboral al desarrollo del curso. Además, reciben acreditación para el Servicio Civil por parte de las unidades académicas ejecutoras. Este trabajo se acompaña con un eje paralelo de proyección comunitaria centrado en la incorporación de los padres de familia a los proyectos institucionales; estas actividades y las redes

  10. Introduction to vector velocity imaging

    DEFF Research Database (Denmark)

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

    it virtually impossible to compensate for the factor and obtain correct velocity estimates for either CFM or spectral velocity estimation. This talk will describe methods for finding the correct velocity by estimating both the axial and lateral component of the velocity vector. The transverse oscillation...... method introduces an ultrasound field that oscillation not only along the ultrasound beam both also transverse to it to estimate both the lateral and axial velocity for the full velocity vector. The correct velocity magnitude can be found from this as well as the instantaneous angle. This can be obtained...... over the full region of interest and a real time image at a frame rate of 20 Hz can be displayed. Real time videos have been obtained from both our research systems and from commercial BK Medical scanners. The vector velocity images reveal the full complexity of the human blood flow. It is easy to see...

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

  12. Algorithms for estimating blood velocities using ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2000-01-01

    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...

  13. Mean droplet size and local velocity in horizontal isothermal free jets of air and water, respectively, viscous liquid in quiescent ambient air

    Energy Technology Data Exchange (ETDEWEB)

    Al Rabadi, S.; Friedel, L. [Fluid Mechanics Institute, Technical University of Hamburg-Harburg (Germany); Al Salaymeh, A. [Mechanical Engineering Department, University of Jordan (Jordan)

    2007-01-15

    Measurements using two-dimensional Phase Doppler Anemometry as well as high speed cinematography in free jets at several nozzle exit pressures and mass flow rates, show that the Sauter mean droplet diameter decreases with increasing air and liquid-phase mass flow ratio due to the increase of the air stream impact on the liquid phase. This leads to substantial liquid fragmentation, respectively primary droplet breakup, and hence, satellite droplet formation with small sizes. This trend is also significant in the case of a liquid viscosity higher than that of water. The increased liquid viscosity stabilizes the droplet formation and breakup by reducing the rate of surface perturbations and consequently droplet distortions, ultimately also leading, in total, to the formation of smaller droplets. The droplet velocity decreases with the nozzle downstream distance, basically due to the continual air entrainment and due to the collisions between the droplets. The droplet collisions may induce further liquid fragmentation and, hence, formation of a number of relatively smaller droplets respectively secondary breakup, or may induce agglomeration to comparatively larger liquid fragments that may rain out of the free jet. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  14. Ambient Space and Ambient Sensation

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    The ambient is the aesthetic production of the sensation of being surrounded. As a concept, 'ambient' is mostly used in relation to the music genre 'ambient music' and Brian Eno's idea of environmental background music. However, the production of ambient sensations must be regarded as a central...

  15. Measurement by γ spectrometry of specific activities of radioisotopes present in vegetal ashes. Study of variations of the ambient radioactivity level in the Grenoble transverse valley from March 1966 to August 1968

    International Nuclear Information System (INIS)

    Chevalier, Michel; Guitton, Pierre; Gagnaire, Janine; Ferard, Guy; Plebin, Roger; LACHET, Bernard

    1969-08-01

    The first part of this report addresses the dosimetry of γ emitting radio-elements which are present in vegetal samples. The dose measurements were performed by spectrometry and results were processed by using a least square method. The second part reports works performed in the Grenoble transverse valley by using the same techniques. Radioactivity fluctuations of various radio-elements ( 40 K, 54 Mn, 95 Zr + 95 Nb, 103 Ru + 106 Rh, 137 Cs, 137 Ba, 140 Ba + 140 La, 144 Ce + 144 Pr) in various vegetal species, in water and in sediments have been monitored in seven points of the Isere river banks, upstream and downstream the city of Grenoble, from March 1966 to August 1968. Fluctuations observed for each radio-element are explained by comparison with physiologic, hydrologic and atmospheric climate conditions. The principles of a systematic control of a site for the detection of possible radioactive pollutions are then defined [fr

  16. Angle independent velocity spectrum determination

    DEFF Research Database (Denmark)

    2014-01-01

    An ultrasound imaging system (100) includes a transducer array (102) that emits an ultrasound beam and produces at least one transverse pulse-echo field that oscillates in a direction transverse to the emitted ultrasound beam and that receive echoes produced in response thereto and a spectral vel...... velocity estimator (110) that determines a velocity spectrum for flowing structure, which flows at an angle of 90 degrees and flows at angles less than 90 degrees with respect to the emitted ultrasound beam, based on the received echoes....

  17. Crustal structure of Australia from ambient seismic noise tomography

    Science.gov (United States)

    Saygin, Erdinc; Kennett, B. L. N.

    2012-01-01

    Surface wave tomography for Australian crustal structure has been carried out using group velocity measurements in the period range 1-32 s extracted from stacked correlations of ambient noise between station pairs. Both Rayleigh wave and Love wave group velocity maps are constructed for each period using the vertical and transverse component of the Green's function estimates from the ambient noise. The full suite of portable broadband deployments and permanent stations on the continent have been used with over 250 stations in all and up to 7500 paths. The permanent stations provide a useful link between the various shorter-term portable deployments. At each period the group velocity maps are constructed with a fully nonlinear tomographic inversion exploiting a subspace technique and the Fast Marching Method for wavefront tracking. For Rayleigh waves the continental coverage is good enough to allow the construction of a 3D shear wavespeed model in a two stage approach. Local group dispersion information is collated for a distribution of points across the continent and inverted for a 1D SV wavespeed profile using a Neighbourhood Algorithm method. The resulting set of 1D models are then interpolated to produce the final 3D wavespeed model. The group velocity maps show the strong influence of thick sediments at shorter periods, and distinct fast zones associated with cratonic regions. Below the sediments the 3D shear wavespeed model displays significant heterogeneity with only moderate correlation with surface tectonic features. For example, there is no evident expression of the Tasman Line marking the eastern edge of Precambrian outcrop. The large number of available inter-station paths extracted from the ambient noise analysis provide detailed shear wavespeed information for crustal structure across the Australian continent for the first time, including regions where there was no prior sampling because of difficult logistics.

  18. Ambient Space and Ambient Sensation

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    The ambient is the aesthetic production of the sensation of being surrounded. As a concept, 'ambient' is mostly used in relation to the music genre 'ambient music' and Brian Eno's idea of environmental background music. However, the production of ambient sensations must be regarded as a central......, dehierarchization, ubiquity and the production of unfocused sensations in contrast to the conventional notion of the aesthetic experience as a focused contemplation of a stationary object....

  19. 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...

  20. Det ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Om begrebet "det ambiente", der beskriver, hvad der sker, når vi fornemmer baggrundsmusikkens diskrete beats, betragter udsigten gennem panoramavinduet eller tager 3D-brillerne på og læner os tilbage i biografsædet. Bogen analyserer, hvorfan ambiente oplevelser skabes, og hvilke konsekvenser det...

  1. Ambient Sensors

    NARCIS (Netherlands)

    Börner, Dirk; Specht, Marcus

    2014-01-01

    This software sketches comprise two custom-built ambient sensors, i.e. a noise and a movement sensor. Both sensors measure an ambient value and process the values to a color gradient (green > yellow > red). The sensors were built using the Processing 1.5.1 development environment. Available under

  2. Transversely Compressed Bonded Joints

    DEFF Research Database (Denmark)

    Hansen, Christian Skodborg; Schmidt, Jacob Wittrup; Stang, Henrik

    2012-01-01

    The load capacity of bonded joints can be increased if transverse pressure is applied at the interface. The transverse pressure is assumed to introduce a Coulomb-friction contribution to the cohesive law for the interface. Response and load capacity for a bonded single-lap joint was derived using...... non-linear fracture mechanics. The results indicated a good correlation between theory and tests. Furthermore, the model is suggested as theoretical base for determining load capacity of bonded anchorages with transverse pressure, in externally reinforced concrete structures....

  3. Transverse beam dynamics

    CERN Document Server

    Wilson, Edmund J N

    2006-01-01

    This contribution describes the transverse dynamics of particles in a synchrotron. It builds on other contributions to the General Accelerator School for definitions of transport matrices and lattice functions. After a discussion of the conservation laws which govern emittance, the effects of closed orbit distortion and other field errors are treated. A number of practical methods of measuring the transverse behaviour of particles are outlined.

  4. 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 wave...... been tried including Transverse Oscillation. This method has been tested in computer simulations, on flow phantoms and in-vivo, and subsequently validated against MRI angiography. Transverse Oscillation is now implemented in a commercial ultrasound scanner from BK Medical (UltraView). In this article...... UltraView is demonstrated on the carotid artery, jugular vein and femoral vein that all runs almost parallel to the skin and thus is angled near 90° to the ultrasound waves. Arterial and venous simple and complex flow with formation of vortices is demonstrated by scanning on the longitudinal axis...

  5. Det Ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Det ambiente er iscenesættelsen af en karakteristisk sanseoplevelse, der er kendetegnet ved fornemmelsen af at være omgivet. I dag bliver begrebet om det ambiente mest anvendt i forbindelse med musikgenren ’ambient musik’. Det ambiente er dog ikke essentielt knyttet til det musikalske, men må...... forstås som et betydeligt bredere fænomen i den moderne æstetiske kultur, der spiller en væsentlig rolle i oplevelsen af moderne transportformer, arkitektur, film, lydkunst, installationskunst og digitale multimedieiscenesættelser. En forståelse af det ambiente er derfor centralt for forståelsen af en...... moderne æstetiseret oplevelseskultur i almindelighed. Da det ambiente ikke hidtil har været gjort til genstand for en mere indgående teoretisk behandling, er der dog stor usikkerhed omkring, hvad fænomenet overhovedet indebærer. Hovedformålet med Det ambiente – Sansning, medialisering, omgivelse er derfor...

  6. The transverse spin

    Energy Technology Data Exchange (ETDEWEB)

    Artru, X. [Institut de Physique Nucleaire de Lyon, IN2P3-CNRS, Universite Claude Bernard, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France)

    2002-07-01

    The aim of this introduction, which is far from exhaustive, was to give an overview on the richness of transverse spin quantity and its differences in comparison with helicity. From the experimental point of view, the physics of quark transversity in deep inelastic reaction is still practically unexplored. This situation will certainly change rapidly, with planned experiments at DESY (HERMES), Brookhaven (RHIC) and CERN (COMPAS), but there is a long way before knowing the transversity distribution, {delta}q(x), as precisely as the helicity distribution, {delta}q(x), now. Unless polarized anti-proton beams become feasible, experiments probing quark transversity will rely mainly on 'quark polarimeters', like {lambda}'s or the Collins effect. These polarimeters will have to be calibrated at e{sup +}e{sup -} colliders. The Collins polarimeter will by the way allow the flavor decomposition of {delta}q(x), using mesons of various charging and strangeness. Quark polarimetry is by itself an interesting topic of non-perturbative QCD, and may teach us something about the breaking of chiral symmetry. Let us recall that, if chiral symmetry were unbroken, transversity would be undefined. The transversity physics program is not at all a 'remake' of the helicity one. Helicity and transversity probe rather different aspects of the hadron structure. Differences between {delta}q(x) and {delta}q(x) will reveal non-relativistic effects in the baryon wave function. Also {delta}q(x) does not couples to gluon distributions, thus it is free from anomaly. In that respect it is a more clean probe than {delta}q(x). In fact, the combination of helicity and transversity measurements will perhaps be the most interesting. Polarized parton densities taking only the helicity degree of freedom are almost 'classical'. Quantum aspects of spin correlations, like violation of Bell's inequality, can be found only when varying the spin quantification axis

  7. Periodismo ambiental

    Directory of Open Access Journals (Sweden)

    Lucía Lemos

    2015-01-01

    Full Text Available Los periodistas toman el tema del medio ambiente cada vez más en serio. El uso de temas relacionados con el medio ambiente, debe estar ligado al análisis socio-económico y a las posibilidades de comunicación y educación de diferentes regiones del mundo. A continuación se presenta un resumen de la situación ambiental, las acciones de prensa y comunicación que se llevan a cabo en América Central (Panamá, El Salvador, Costa Rica y en Sudamérica Brasil,Colombia, Chile, México, y Perú. Se concluye en la necesidad de formar hábitos ecológicos. Los comunicadores deben presentar soluciones a los problemas, fomentar campañas comunes, compartir información y velar por el ambiente ambiente para que las generaciones futuras no tengan que perecer.

  8. Noninterceptive transverse beam diagnostics

    International Nuclear Information System (INIS)

    Chamberlin, D.D.; Minerbo, G.N.; Teel, L.E. Jr.; Gilpatrick, J.D.

    1981-01-01

    The transverse emittance properties of a high-current linear accelerator may be measured by using TV cameras sensitive to the visible radiation emitted following beam interactions with residual gas. This paper describes the TV system being used to measure emittances for the Fusion Materials Irradiation Test (FMIT) project

  9. Role of Inelastic Transverse Compressive Behavior and Multiaxial Loading on the Transverse Impact of Kevlar KM2 Single Fiber

    Directory of Open Access Journals (Sweden)

    Subramani Sockalingam

    2017-02-01

    Full Text Available High-velocity transverse impact of ballistic fabrics and yarns by projectiles subject individual fibers to multi-axial dynamic loading. Single-fiber transverse impact experiments with the current state-of-the-art experimental capabilities are challenging due to the associated micron length-scale. Kevlar® KM2 fibers exhibit a nonlinear inelastic behavior in transverse compression with an elastic limit less than 1.5% strain. The effect of this transverse behavior on a single KM2 fiber subjected to a cylindrical and a fragment-simulating projectile (FSP transverse impact is studied with a 3D finite element model. The inelastic behavior results in a significant reduction of fiber bounce velocity and projectile-fiber contact forces up to 38% compared to an elastic impact response. The multiaxial stress states during impact including transverse compression, axial tension, axial compression and interlaminar shear are presented at the location of failure. In addition, the models show a strain concentration over a small length in the fiber under the projectile-fiber contact. A failure criterion, based on maximum axial tensile strain accounting for the gage length, strain rate and multiaxial loading degradation effects are applied to predict the single-fiber breaking speed. Results are compared to the elastic response to assess the importance of inelastic material behavior on failure during a transverse impact.

  10. Large transverse momentum phenomena

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1977-09-01

    It is pointed out that it is particularly significant that the quantum numbers of the leading particles are strongly correlated with the quantum numbers of the incident hadrons indicating that the valence quarks themselves are transferred to large p/sub t/. The crucial question is how they get there. Various hadron reactions are discussed covering the structure of exclusive reactions, inclusive reactions, normalization of inclusive cross sections, charge correlations, and jet production at large transverse momentum. 46 references

  11. Transverse tomography and radiotherapy

    International Nuclear Information System (INIS)

    Leer, J.W.H.

    1982-01-01

    This study was intended to delineate the indications for radiotherapy treatment-planning with the help of computerized axial tomography (C.T.) and transverse analog tomography (T.A.T.). Radiotherapy localisation procedures with the conventional method (simulator), with the CT-scanner and with the transverse analog tomograph (T.A.T., Simtomix, Oldelft) were compared. As criterium for evaluation differences in reconstruction drawing based on these methods were used. A certain method was judged ''superior'' to another if the delineation of the target volume was more accurate, if a better impression was gained of the site of (for irradiation) organs at risk, or if the localisation could only be performed with that method. The selected group of patients consisted of 120 patients for whom a reconstruction drawing in the transverse plane was made according to the treatment philosophy. In this group CT-assisted localisation was judged on 68 occasions superior to the conventional method. In a number of cases it was found that a ''standard'' change in a standard target volume, on the base of augmented anatomical knowledge, made the conventional method sufficient. The use of CT-scanner for treatment planning was estimated. For ca. 270/1000 new patients a CT-scan is helpful (diagnostic scan), for 140 of them the scan is necessary (planning scan). The quality of the anatomical information obtained with the T.A.T. does not yet fall within acceptable limits, but progress has been made. (Auth.)

  12. Orbital velocity

    OpenAIRE

    Modestino, Giuseppina

    2016-01-01

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

  13. Exploration of Wave Development during Yarn Transverse Impact

    Directory of Open Access Journals (Sweden)

    Matthew Hudspeth

    2017-05-01

    Full Text Available Single yarns have been impacted in a transverse fashion so as to probe the characteristics of resulting wave development. Longitudinal wave speeds were tracked in efforts to directly measure the yarn tensile stiffness, resulting in a slight increase in the modulus of Kevlar® KM2 and Dyneema® SK76. Additionally, the load developed in AuTx® and Kevlar® KM2 yarns behind the longitudinal wave front has been recorded, providing additional verification for the Smith relations. Further effort to bolster the Smith equations has been successfully performed via tracking transverse wave speeds in AuTx® yarns over a range of impacting velocities. Additional emphasis has been placed at understanding the transverse wave development around the yarn critical velocity, demonstrating that there is a velocity zone where partial yarn failure is detected. Above the critical velocity, measurement of early time transverse wave speeds also agrees with the Smith solution, though the wave speed quickly reduces in value due to the drop in tensile stresses resulting from filament rupture. Finally, the Smith equations have been simplified and are compared to the Cunniff equation, which bear a striking resemblance. Due to such a resemblance, it is suggested that yarn critical velocity experiments can be performed on trial yarn material, and the effect of modifying yarn mechanical properties is discussed.

  14. 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.

  15. Figures of transversality

    DEFF Research Database (Denmark)

    Gammeltoft, Tine

    2008-01-01

    In this article, I explore how prenatal screening is imbricated within state agendas, aspirations, and imaginings in contemporary Vietnam. In an effort to develop new ethnographic tropes for understanding the formation called "the state," I argue for a phenomenological take that emphasizes its...... affective and embodied aspects. Seeing the anomalous fetus as a "figure of transversality," as a critical focus for powerful imaginings and desires, I show how state–society relations in Vietnam are suffused by visceral affectivity and moral engagement. In the realm of reproduction, intense sentiments...... of anxiety, dread, desire, ambition, and hope tie together the state and its citizens, animating individual aspirations as well as national population policies....

  16. 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....... The new estimator automatically compensates for the axial velocity when determining the transverse velocity. The estimation is optimized by using a lag different from one in the estimation process, and noise artifacts are reduced by averaging RF samples. Further, compensation for the axial velocity can...... be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce 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...

  17. Ambient diagnostics

    CERN Document Server

    Cai, Yang

    2014-01-01

    Part I. FundamentalsIntroductionWhat is Ambient Diagnostics?Diagnostic ModelsMultimedia IntelligenceCrowd SourcingSoft SensorsScience of SimplicityPersonal DiagnosesBasic AlgorithmsBasic ToolsSummaryProblemsTransformationEarly Discoveries of Heartbeat PatternsTransforms, Features, and AttributesSequential FeaturesSpatiotemporal FeaturesShape FeaturesImagery FeaturesFrequency Domain FeaturesMulti-Resolution FeaturesSummaryProblemsPattern RecognitionSimilarities and DistancesClustering MethodsClassification MethodsClassifier Accuracy MeasuresSummaryProblemsPart II. Multimedia IntelligenceSound RecognitionMicrophone AppsModern Acoustic Transducers (Microphones)Frequency Response CharacteristicsDigital Audio File FormatsHeart Sound SensingLung Sound SensingSnore MeterSpectrogram (STFT)Ambient Sound AnalysisSound RecognitionRecognizing Asthma SoundPeak ShiftFeature CompressionRegroupingNoise IssuesFuture ApplicationsSummaryProblemsColor SensorsColor SensingHuman Color VisionColor SensorsColor Matching ExperimentsC...

  18. An In-vivo investigation of transverse flow estimation

    DEFF Research Database (Denmark)

    Udesen, Jesper; Jensen, Jørgen Arendt

    2004-01-01

    , and 1.4 seconds of data is acquired. Using 2 parallel receive beamformers a transverse oscillation is introduced with an oscillation period 1.2 mm. The velocity estimation is performed using an extended autocorrelation algorithm. The volume flow can be estimated with a relative standard deviation of 13...

  19. Effect of Channel Bends on Transverse Mixing | Engmann | Nigerian ...

    African Journals Online (AJOL)

    Velocity and tracer concentration measurements made in a meandering channel are used to discuss the effect of bends on the transverse mixing of a conservative tracer introduced into the flow. It is shown that bend induced spiral motion greatly enhance the mixing potential of meandering channel flows; The magnitude of ...

  20. Transverse section scanning mechanism

    International Nuclear Information System (INIS)

    Doherty, E.J.

    1978-01-01

    Apparatus is described for scanning a transverse, radionuclide scan-field using an array of focussed collimators. The collimators are movable tangentially on rails, driven by a single motor via a coupled screw. The collimators are also movable in a radial direction on rails driven by a step motor via coupled screws and bevel gears. Adjacent bevel gears rotate in opposite directions so adjacent collimators move in radially opposite directions. In use, the focal point of each collimator scans at least half of the scan-field, e.g. a human head located in the central aperture, and the electrical outputs of detectors associated with each collimator are used to determine the distribution of radioactive emission intensity at a number of points in the scan-field. (author)

  1. Construindo cidadania ambiental na escola

    Directory of Open Access Journals (Sweden)

    Cibele Schwanke

    2014-03-01

    Full Text Available http://dx.doi.org/10.5007/1807-0221.2013v10n16p14 O forte componente transversal da Educação Ambiental possibilita sua inserção em vários espaços e níveis de escolaridade. No ensino fundamental, constitui-se em uma importante ferramenta para criar espaços que permitam a abordagem de temáticas socioambientais atuais, de forma crítica e participativa. O presente trabalho tem como objetivo apresentar o Projeto Construindo Cidadania Ambiental, executado por bolsistas do Grupo PET - Conexões Gestão Ambiental em unidades escolares, explicitando sua filosofia de implantação e resultados obtidos até o momento. Verifica-se que sua natureza interdisciplinar e integrada permite uma efetiva interação com o corpo docente e discente da escola, bem como permite a prática de uma educação ambiental crítica e transformadora.

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

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Munk, Peter

    1999-01-01

    The full blood velocity vector must be estimated in medical ultrasound to give a correct depiction of the blood flow. This can be done by introducing a transversely oscillating pulse-echo ultrasound field, which makes the received signal influenced by a transverse motion. Such an approach...... was suggested in [1]. Here the conventional autocorrelation approach was used for estimating the transverse velocity and a compensation for the axial motion was necessary in the estimation procedure. This paper introduces a new estimator for determining the two-dimensional velocity vector and a new dynamic...... beamforming method. A modified autocorrelation approach employing fourth order moments of the input data is used for velocity estimation. The new estimator calculates the axial and lateral velocity component independently of each other. The estimation is optimized for differences in axial and lateral...

  3. Classical Weyl transverse gravity

    Energy Technology Data Exchange (ETDEWEB)

    Oda, Ichiro [University of the Ryukyus, Department of Physics, Faculty of Science, Nishihara, Okinawa (Japan)

    2017-05-15

    We study various classical aspects of the Weyl transverse (WTDiff) gravity in a general space-time dimension. First of all, we clarify a classical equivalence among three kinds of gravitational theories, those are, the conformally invariant scalar tensor gravity, Einstein's general relativity and the WTDiff gravity via the gauge-fixing procedure. Secondly, we show that in the WTDiff gravity the cosmological constant is a mere integration constant as in unimodular gravity, but it does not receive any radiative corrections unlike the unimodular gravity. A key point in this proof is to construct a covariantly conserved energy-momentum tensor, which is achieved on the basis of this equivalence relation. Thirdly, we demonstrate that the Noether current for the Weyl transformation is identically vanishing, thereby implying that the Weyl symmetry existing in both the conformally invariant scalar tensor gravity and the WTDiff gravity is a ''fake'' symmetry. We find it possible to extend this proof to all matter fields, i.e. the Weyl-invariant scalar, vector and spinor fields. Fourthly, it is explicitly shown that in the WTDiff gravity the Schwarzschild black hole metric and a charged black hole one are classical solutions to the equations of motion only when they are expressed in the Cartesian coordinate system. Finally, we consider the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology and provide some exact solutions. (orig.)

  4. 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...... yields a change in the received signals. The method uses two ultrasound beams for sampling the in-phase and quadrature component of the lateral field, and a set of samples (in-phase and quadrature in both time and space) are taken for each pulse-echo line. These four samples are then used...... 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...

  5. A critical analysis of transverse vorticity measurements in a large plane shear layer

    Science.gov (United States)

    Foss, J. F.; Ali, S. K.; Haw, R. C.

    1987-01-01

    An evaluation is made of the roles played in four-wire hot wire probe arrays by the influence of (1) the transverse velocity component on pitch angle measurement; (2) the instantaneous spatial gradient of the pitch angle on transverse vorticity computation; (3) the uncertainties in the magnitude of instantaneous pitch angle spatial gradient in the transverse vorticity computation; and (4) the spatial dimension of the microcirculation domain and the evaluation of transverse vorticity. Attention is given to the probe configuration and its computation algorithm.

  6. Comparative study of methods for blood flow measurement within transverse sinuses by using MR

    International Nuclear Information System (INIS)

    Gao Gejun; Feng Xiaoyuan; Yang Bojie; Geng Daoying

    2003-01-01

    Objective: To assess the accuracy of two-dimensional phase contrast (2D-PC) MR method for blood flow measurement within transverse sinuses by comparing this method with cine phase contrast (cine-PC) MR and Doppler in volunteers and patients. Methods: (1) A total of 12 transverse sinuses were examined in 8 healthy volunteers. 2D-PC MR and cine-PC MR were used respectively to measure the transverse area of flow, the flow velocities, and the volumetric flow rates in the same position in every transverse sinus. Paired t-test was used for comparison between the results determined by 2D-PC MR and that determined by cine-PC MR. (2) A total of 6 transverse sinuses were examined in 5 patients who needed operation. 2D-PC MR was used to determine the blood flow velocity of transverse sinus before operation, and Doppler was used to determine the blood flow velocity of the same transverse sinus during operation. The linear regression analysis was used for statistical analysis. Results: (1) Statistical analysis indicated that there were no significant difference among the transverse area of flow (t = -1.106, P = 0.293), the flow velocities (t = 0.262, P = 0.798), and the volumetric flow rates (t = 0.439, P = 0.669) measured by using 2D-PC MR and cine PC MR, respectively. (2) The correlation between flow velocities determined by 2D-PC MR imaging before operation and that determined by Doppler during operation was in excellent agreement (Y-circumflex = 1.303 x + 0.62, r 2 = 0.88). Conclusion: 2D-PC MR may be a practical convenient method for blood flow measurement within transverse sinuses system

  7. Transverse correlations in multiphoton entanglement

    International Nuclear Information System (INIS)

    Wen Jianming; Rubin, Morton H.; Shih Yanhua

    2007-01-01

    We have analyzed the transverse correlation in multiphoton entanglement. The generalization of quantum ghost imaging is extended to the N-photon state. The Klyshko's two-photon advanced-wave picture is generalized to the N-photon case

  8. 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...... person. In case 3) the estimated vector velocities are compared with numerical simulations. Qualitatively the same flow pattern can be seen in both simulations and in the vector velocity images. Furthermore a vortex is identified in the carotid sinus at the deceleration phase after the peak systole...

  9. Acoustic reflection log in transversely isotropic formations

    Science.gov (United States)

    Ronquillo Jarillo, G.; Markova, I.; Markov, M.

    2018-01-01

    We have calculated the waveforms of sonic reflection logging for a fluid-filled borehole located in a transversely isotropic rock. Calculations have been performed for an acoustic impulse source with the characteristic frequency of tens of kilohertz that is considerably less than the frequencies of acoustic borehole imaging tools. It is assumed that the borehole axis coincides with the axis of symmetry of the transversely isotropic rock. It was shown that the reflected wave was excited most efficiently at resonant frequencies. These frequencies are close to the frequencies of oscillations of a fluid column located in an absolutely rigid hollow cylinder. We have shown that the acoustic reverberation is controlled by the acoustic impedance of the rock Z = Vphρs for fixed parameters of the borehole fluid, where Vph is the velocity of horizontally propagating P-wave; ρs is the rock density. The methods of waveform processing to determine the parameters characterizing the reflected wave have been discussed.

  10. Novel self-similar rotating solutions of nonideal transverse magnetohydrodynamics

    Science.gov (United States)

    Shokri, M.; Sadooghi, N.

    2017-12-01

    The evolution of electromagnetic and thermodynamic fields in a nonideal fluid is studied in the framework of ultrarelativistic transverse magnetohydrodynamics (MHD), which is essentially characterized by electric and magnetic fields being transverse to the fluid velocity and translational invariance in the transverse plane. Extending the method of self-similar solutions of relativistic hydrodynamics to the case of nonconserved charges, the differential equations of nonideal transverse MHD are solved, and two novel sets of self-similar solutions are derived. The first set turns out to be a boost-invariant and exact solution, which is characterized by nonrotating electric and magnetic fields. The second set is a nonboost-invariant solution, which is characterized by rotating electric and magnetic fields. The rotation occurs with increasing rapidity η , as the angular velocity is defined by ω0≡∂ζ/∂η =∂ϕ/∂η , with ζ and ϕ being the angles of local electric and magnetic vectors with respect to a certain fixed axis in the transverse plane. For both sets of solutions, the electric and magnetic fields are either parallel or antiparallel to each other in the local rest frame of the fluid. Performing a complete numerical analysis, the effects of finite electric conductivity as well as electric and magnetic susceptibilities of the medium on the evolution of rotating and nonrotating MHD solutions are explored, and the interplay between the angular velocity ω0 and these quantities is scrutinized. The lifetime of electromagnetic fields and the evolution of the temperature of the electromagnetized fluid are shown to be affected by ω0.

  11. Skin effect of microwaves and transverse pseudowaves in plasmas

    International Nuclear Information System (INIS)

    Minami, Kazuo

    1977-09-01

    Using linearized Vlasov-Maxwell equations, the skin effect of microwaves and transverse pseudowaves excited by an idealized grid antenna in plasmas are analyzed. It is shown that the latter is predominant over the former, in such a plasma that ω sub(p) v sub(t)/ωc >= 1, where ω sub(p) and ω are the plasma and microwave angular frequencies, v sub(t) and c are the electron thermal and light velocities, respectively. (auth.)

  12. Transverse vertical dispersion in groundwater and the capillary fringe.

    Science.gov (United States)

    Klenk, I D; Grathwohl, P

    2002-09-01

    Transverse dispersion is the most relevant process in mass transfer of contaminants across the capillary fringe (both directions), dilution of contaminants, and mixing of electron acceptors and electron donors in biodegrading groundwater plumes. This paper gives an overview on literature values of transverse vertical dispersivities alpha(tv) measured at different flow velocities and compares them to results from well-controlled laboratory-tank experiments on mass transfer of trichloroethene (TCE) across the capillary fringe. The measured values of transverse vertical dispersion in the capillary fringe region were larger than in fully saturated media, which is credited to enhanced tortuosity of the flow paths due to entrapped air within the capillary fringe. In all cases, the values observed for alpha(tv) were < 1 mm. The new measurements and the literature values indicate that alpha(tv) apparently declines with increasing flow velocity. The latter is attributed to incomplete diffusive mixing at the pore scale (pore throats). A simple conceptual model, based on the mean square displacement and the pore size accounting for only partial diffusive mixing at increasing flow velocities, shows very good agreement with measured and published data.

  13. In Vivo Validation of a Blood Vector Velocity Estimator with MR Angiography

    DEFF Research Database (Denmark)

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

    2009-01-01

    Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound beam direction. This implies that a Doppler angle under examination close to 90° results in unreliable information about the true blood direction and blood velocity. The novel method...... transverse oscillation (TO), which combines estimates of the axial and the transverse velocity components in the scan plane, makes it possible to estimate the vector velocity of the blood regardless of the Doppler angle. The present study evaluates the TO method with magnetic resonance phase contrast......° for TO measurements. The correlation between the stroke volume estimated by TO and MRA was 0.91 (p

  14. Single transverse mode protein laser

    Science.gov (United States)

    Dogru, Itir Bakis; Min, Kyungtaek; Umar, Muhammad; Bahmani Jalali, Houman; Begar, Efe; Conkar, Deniz; Firat Karalar, Elif Nur; Kim, Sunghwan; Nizamoglu, Sedat

    2017-12-01

    Here, we report a single transverse mode distributed feedback (DFB) protein laser. The gain medium that is composed of enhanced green fluorescent protein in a silk fibroin matrix yields a waveguiding gain layer on a DFB resonator. The thin TiO2 layer on the quartz grating improves optical feedback due to the increased effective refractive index. The protein laser shows a single transverse mode lasing at the wavelength of 520 nm with the threshold level of 92.1 μJ/ mm2.

  15. Transverse permeability of woven fabrics

    NARCIS (Netherlands)

    Grouve, Wouter Johannes Bernardus; Akkerman, Remko; Loendersloot, Richard; van den Berg, S.

    2008-01-01

    The transverse permeability is an essential input in describing the consolidation process of CETEX® laminates. A two-dimensional, finite difference based, Stokes flow solver has been developed to determine the mesoscopic permeability of arbitrary fabric structures. The use of a multigrid solver

  16. Atmosphere and Ambient Space

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

  17. A Critical Characteristic in the Transverse Galloping Pattern.

    Science.gov (United States)

    Wei, Xiaohui; Long, Yongjun; Wang, Chunlei; Wang, Shigang

    2015-01-01

    Transverse gallop is a common gait used by a large number of quadrupeds. This paper employs the simplified dimensionless quadrupedal model to discuss the underlying mechanism of the transverse galloping pattern. The model is studied at different running speeds and different values of leg stiffness, respectively. If the horizontal running speed reaches up to a critical value at a fixed leg stiffness, or if the leg stiffness reaches up to a critical value at a fixed horizontal speed, a key property would emerge which greatly reduces the overall mechanical forces of the dynamic system in a proper range of initial pitch angular velocities. Besides, for each horizontal speed, there is an optimal stiffness of legs that can reduce both the mechanical loads and the metabolic cost of transport. Furthermore, different body proportions and landing distance lags of a pair of legs are studied in the transverse gallop. We find that quadrupeds with longer length of legs compared with the length of the body are more suitable to employ the transverse galloping pattern, and the landing distance lag of a pair of legs could reduce the cost of transport and the locomotion frequency.

  18. Introduction to Transverse Beam Dynamics

    CERN Document Server

    Holzer, B.J.

    2014-01-01

    In this chapter we give an introduction to the transverse dynamics of the particles in a synchrotron or storage ring. The emphasis is more on qualitative understanding rather than on mathematical correctness, and a number of simulations are used to demonstrate the physical behaviour of the particles. Starting from the basic principles of how to design the geometry of the ring, we review the transverse motion of the particles, motivate the equation of motion, and show the solutions for typical storage ring elements. Following the usual treatment in the literature, we present a second way to describe the particle beam, using the concept of the emittance of the particle ensemble and the beta function, which reflects the overall focusing properties of the ring. The adiabatic shrinking due to Liouville's theorem is discussed as well as dispersive effects in the most simple case.

  19. Transversal Lines of the Debates

    Directory of Open Access Journals (Sweden)

    Yolanda Onghena

    1998-12-01

    Full Text Available The Transversal Lines of the Debates gathers for publication the presentations of the scholars invited to the seminar. In the papers, Yolanda Onghena observes that the evolution from the cultural to the inter-cultural travels along four axes: the relations between cultureand society; the processes of change within identity-based dynamics; the representations of the Other; and, interculturality. Throughout the presentations and subsequent debates, whenever the different participants referred to aspects of the cultural identity problematic--”angst”, “obsession”, “deficit”, manipulation”, and others, these same participants in the Transversal Lines of the Debates also showed that, in certain areas, an optimistic viewpoint is not out of the question.

  20. 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

  1. TRANSVERSALITY AND INTERDISCIPLINARY DISCUSSION IN ...

    African Journals Online (AJOL)

    2010-07-19

    Jul 19, 2010 ... e o lo g ic a l S tu d ie s http://www.hts.org.za. HTS. Original Research. A rtic le #. 9. 1. 0. (page number not for citation purposes). TRANSVERSALITY ... mentorship. An interview with a mentor and mentee was used as a local, real narrative in the process. In the final section, the author reflected upon his own ...

  2. Propuesta de inclusión de la educación ambiental como eje transversal en el segundo año de Educación General Básica de la escuela Velasco Ibarra. Durante el año lectivo 2007-2008

    OpenAIRE

    Jara Idrovo, Tatiana Monserrath; Peña Aguirre, María Augusta

    2008-01-01

    A partir de los años sesenta y debido a múltiples catástrofes ambientales, el moviendo ecologista y la ecología (ciencia que estudia los ecosistemas, las interacciones de los elementos que los componen y las relaciones de éstos con el entorno), empiezan a tomar fuerza en el planeta, reiterando que los individuos estaban malgastando los recursos naturales. Es así como la visión de la Educación Ambiental, evoluciona no sólo científicamente, sino que es tratada como un tema interdisciplinar, y p...

  3. The future is 'ambient'

    Science.gov (United States)

    Lugmayr, Artur

    2006-02-01

    The research field of ambient media starts to spread rapidly and first applications for consumer homes are on the way. Ambient media is the logical continuation of research around media. Media has been evolving from old media (e.g. print media), to integrated presentation in one form (multimedia - or new media), to generating a synthetic world (virtual reality), to the natural environment is the user-interface (ambient media), and will be evolving towards real/synthetic undistinguishable media (bio-media or bio-multimedia). After the IT bubble was bursting, multimedia was lacking a vision of potential future scenarios and applications. Within this research paper the potentials, applications, and market available solutions of mobile ambient multimedia are studied. The different features of ambient mobile multimedia are manifold and include wearable computers, adaptive software, context awareness, ubiquitous computers, middleware, and wireless networks. The paper especially focuses on algorithms and methods that can be utilized to realize modern mobile ambient systems.

  4. Transversals in non-discrete groups

    Indian Academy of Sciences (India)

    Abstract. The concept of 'topological right transversal' is introduced to study right transversals in topological groups. Given any right quasigroup S with a Tychonoff topol- ogy T , it is proved that there exists a Hausdorff topological group in which S can be embedded algebraically and topologically as a right transversal of a ...

  5. Appraisal of transverse nasal groove: A study

    Directory of Open Access Journals (Sweden)

    Belagola D Sathyanarayana

    2012-01-01

    Full Text Available Background: Transverse nasal groove is a condition of cosmetic concern which awaits due recognition and has been widely described as a shallow groove that extends transversely over the dorsum of nose. However, we observed variations in the clinical presentations of this entity, hitherto undescribed in literature. Aims: We conducted a clinicoepidemiological study of transverse nasal lesions in patients attending our outpatient department. Methods: We conducted a prospective observational study. We screened all patients attending our out-patient department for presence of transverse nasal lesions, signs of any dermatosis and associated other skin conditions. Results: One hundred patients were recruited in the study. Females (80% predominated over males. Most patients were of 15-45 years age group (70%. Majority of the transverse nasal lesions were classical transverse nasal groove (39% and others included transverse nasal line (28%, strip (28%, ridge (4% and loop (1%. Seborrhoeic diathesis was the most common condition associated with transverse nasal lesion. Conclusions: Occurrence of transverse nasal line, strip, ridge and loop, in addition to classical transverse nasal groove implies that latter is actually a subset of transverse nasal lesions. Common association of this entity with seborrheic dermatitis, seborrhea and dandruff raises a possibility of whether transverse nasal lesion is a manifestation of seborrheic diathesis.

  6. Transversity of quarks in a nucleon

    Indian Academy of Sciences (India)

    The transversity distribution of quarks in a nucleon is one of the three fundamental distributions, that characterize nucleon's properties in hard scattering processes at leading twist (twist 2). It measures the distribution of quark transverse spin in a nucleon polarized transverse to its (infinite) momentum. It is a chiral-odd ...

  7. Contribution to the study of transverse turbulent diffusion in streams

    International Nuclear Information System (INIS)

    Masson, Olivier

    1991-01-01

    In this research our objective is to study the turbulent diffusion in a water flow, in particular the transverse diffusion. According to formulae reviewed in literature the diffusion coefficients (K) may be expressed as a function of several velocity parameters. A synthetic formula depending on a macro-scale length of turbulence L x and a turbulent intensity √(u' 2 ) is proposed: K = β.L x .U-bar.(√(u' 2 /U-bar)) 2 . In order to validate this expression we performed two in situ experiments (one in a wide river and the other in an irrigation canal) with a double set of measurements: turbulent velocities and concentrations of a diffusing tracer. The first set gives us usable data in our formula. The results, compared with values available in literature, give a good agreement. Moreover it appears that it is possible to roughly divide the data in two groups according to (1) the cross section shape and (2) the bed roughness. The second set allows us to evaluate a global turbulent mixing coefficient. The coefficients calculated by the two methods are in accordance so our formula is validated. Nevertheless some problems appear because of what is called secondary currents and coherent structures as those seen above bed cracks in the Garonne river. Those phenomenon may play a major part upon turbulent diffusion in real streams. Although they were made conspicuous by an analysis of transverse velocity component, it has not been yet possible to quantify their effects. (author) [fr

  8. Modeling Transverse Chemotaxis in Porous Media

    Science.gov (United States)

    Porter, M. L.; Valdés-Parada, F. J.; Wood, B. D.

    2009-12-01

    The movement of microorganisms toward a chemical attractant (chemotaxis) has been shown to aid in subsurface contaminant degradation and enhanced oil recovery. However, chemotaxis is inherently a pore scale process that must be upscaled to arrive at continuum scale models for field applications. In this work, the method of volume averaging is used to upscale the microscale chemotactic microbial transport equations in order to obtain the corresponding macroscale models for the mass balance of bacteria and the chemical attractant to which they respond. As a first approach, cellular growth/death and consumption of the attractant by chemical reaction are assumed to be negligible with respect to convective and diffusive transport mechanisms. Two effective medium coefficients are introduced in the model, namely a total motility tensor and a total velocity vector. Under certain conditions, it is shown that the coefficients can differ considerably from the values corresponding to non-chemotactic transport. The model is validated by comparing the predicted transverse motility coefficients and concentration profiles to those measured within an engineered porous medium. For the concentration profiles, we introduced a lag that accounts for the difference between the arrival time of the microorganisms and the their chemotactic response to the attractant.

  9. Elastic and piezoelectric properties, sound velocity and Debye ...

    Indian Academy of Sciences (India)

    The phase transition, the independent elastic stiffness constants, the bulk modulus, the direct and converse piezoelectric coefficients, the longitudinal, transverse, and average sound velocities, and finally the Debye temperature under pressure are studied. The results obtained are generally lower than the available ...

  10. Noninterceptive transverse-beam measurements

    International Nuclear Information System (INIS)

    Chamberlin, D.D.; Minerbo, G.N.; Mottershead, C.T.

    1981-01-01

    Totally noninterceptive techniques for accurate measurement of transverse beam distributions are required for high-current continuous wave (cw) linacs, such as the Fusion Materials Irradiation Test (FMIT) accelerator. Sensors responding to visible radiation from beam interactions with residual gas and computer algorithms reconstructing spatial and phase space distributions have been implemented. This paper reports on early measurements of the beam from the injector of the prototype FMIT facility at Los Alamos. The first section indicates hardware setup and performance whereas the second section describes the data-processing software. The third section outlines the resultant measurements and further developments are discussed in the fourth section

  11. Entropy and transverse section reconstruction

    International Nuclear Information System (INIS)

    Gullberg, G.T.

    1976-01-01

    A new approach to the reconstruction of a transverse section using projection data from multiple views incorporates the concept of maximum entropy. The principle of maximizing information entropy embodies the assurance of minimizing bias or prejudice in the reconstruction. Using maximum entropy is a necessary condition for the reconstructed image. This entropy criterion is most appropriate for 3-D reconstruction of objects from projections where the system is underdetermined or the data are limited statistically. This is the case in nuclear medicine time limitations in patient studies do not yield sufficient projections

  12. Transverse thermopherotic MHD Oldroyd-B fluid with Newtonian heating

    Science.gov (United States)

    Mehmood, R.; Rana, S.; Nadeem, S.

    2018-03-01

    Hydromagnetic transverse flow of an Oldroyd-B type fluid with suspension of nanoparticles and Newtonian heating effects is conferred in this article. Relaxation and Retardation time effects are taken into consideration. Using suitable transformations physical problem is converted into non-linear ordinary differential equations which are tackled numerically via Runge-Kutta Fehlberg integration scheme. Illustration of embedded constraints on flow characteristics are extracted through graphs. The physical response of velocity, temperature and concentration are investigated computationally. Momentum boundary layer thickness decreases but local heat and mass flux rises for Deborah number and Hartman number. The results provide interesting insights into certain applicable transport phenomena involving hydromagnetic rheological fluids.

  13. Delaminations in composite plates under transverse impact loads - Experimental results

    Science.gov (United States)

    Finn, Scott R.; He, Ye-Fei; Springer, George S.

    1993-01-01

    Tests were performed measuring the locations and geometries of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite/PEEK plates subjected to transverse impact loads. The data provide specific information on the effects of impactor velocity, impactor mass, material, thickness of back ply group, difference in fiber orientation between adjacent ply groups, plate thickness, and impactor nose radius. The data were compared to the results of the Finn-Springer model. The model was found to describe the data with reasonable accuracy.

  14. Localization by Acoustic Emission in Transversely Isotropic Slate

    Directory of Open Access Journals (Sweden)

    Bjorn Debecker

    2011-01-01

    Full Text Available A method for localization by acoustic emission in transversely isotropic media is developed and validated. Velocities are experimentally measured and then used to calculate a database of theoretical arrival times for a large number of positions. During an actual test, positions are assigned by comparing measured arrival times with the database's arrival times. The method is applied during load tests on slate samples and compared with visual observations of fractures. The localization method allowed for a good identification of the regions of fracturing at different stages during the test.

  15. Licenciamento ambiental e sustentabilidade

    Directory of Open Access Journals (Sweden)

    Marcelo Macedo Valinhas

    2011-12-01

    Full Text Available A sustentabilidade está apoiada principalmente nas dimensões econômica, ambiental e social. No entanto, sem a dimensão política ela não se constrói. Um dos principais instrumentos de comando e controle da política nacional de meio ambiente, o licenciamento ambiental é um processo contínuo de gestão ambiental pública e privada. Analisou-se o processo de licenciamento ambiental como acoplamento estrutural entre os sistemas social, econômico e ambiental. Apesar da constatação de críticas aos mecanismos de comando e controle dos últimos anos, foi verificado que o Estado do Rio de Janeiro tem buscado integrar a política ambiental do Estado à gestão ambiental privada e que esta integração busca atender às demandas dos sistemas sociais e econômicos para as questões ambientais. Em linhas gerais, este caminho segue as estratégias e ações propostas na Agenda 21 brasileira.

  16. Transverse and Longitudinal proximity effect

    Science.gov (United States)

    Jalan, Pryianka; Chand, Hum; Srianand, Raghunathan

    2018-04-01

    With close pairs (˜1.5arcmin) of quasars (QSOs), absorption in the spectra of a background quasar in the vicinity of a foreground quasar can be used to study the environment of the latter quasar at kpc-Mpc scales. For this we used a sample of 205 quasar pairs from the Sloan Digital Sky-Survey Data Release 12 (SDSS DR12) in the redshift range of 2.5 to 3.5 by studying their H I Ly-α absorption. We study the environment of QSOs both in the longitudinal as well as in the transverse direction by carrying out a statistical comparison of the Ly-α absorption lines in the quasar vicinity to that of the absorption lines caused by the inter-galactic medium (IGM). This comparison was done with IGM, matched in absorption redshift and signal-to-noise ratio (SNR) to that of the proximity region. In contrast to the measurements along the line-of-sight, the regions transverse to the quasars exhibit enhanced H I Ly-α absorption. This discrepancy can either be interpreted as due to an anisotropic emission from the quasars or as a consequence of their finite lifetime.

  17. The effect of laser beam size in a zig-zag collimator on transverse ...

    Indian Academy of Sciences (India)

    to achieve high number densities of trapped cold atoms [17,18]. In zig-zag method, the transverse component of velocity of a moving atom in atomic beam is reduced by a laser beam propagating at an angle with respect to the axis of the atomic beam. In this method, a zig-zag path for the cooling laser beam is generated.

  18. Transverse section radionuclide scanning system

    International Nuclear Information System (INIS)

    Kuhl, D.E.; Edwards, R.Q.

    1976-01-01

    This invention provides a transverse section radionuclide scanning system for high-sensitivity quantification of brain radioactivity in cross-section picture format in order to permit accurate assessment of regional brain function localized in three dimensions. High sensitivity crucially depends on overcoming the heretofore known raster type scanning, which requires back and forth detector movement involving dead-time or partial enclosure of the scan field. Accordingly, this invention provides a detector array having no back and forth movement by interlaced detectors that enclose the scan field and rotate as an integral unit around one axis of rotation in a slip ring that continuously transmits the detector data by means of laser emitting diodes, with the advantages that increased amounts of data can be continuously collected, processed and displayed with increased sensitivity according to a suitable computer program. 5 claims, 11 figures

  19. Resolution enhancement of slam using transverse wave

    International Nuclear Information System (INIS)

    Ko, Dae Sik; Moon, Gun; Kim, Young H.

    1997-01-01

    We studied the resolution enhancement of a novel scanning laser acoustic microscope (SLAM) using transverse waves. Mode conversion of the ultrasonic wave takes place at the liquid-solid interface and some energy of the insonifying longitudinal waves in the water will convert to transverse wave energy within the solid specimen. The resolution of SLAM depends on the size of detecting laser spot and the wavelength of the insonifying ultrasonic waves. Since the wavelength of the transverse wave is shorter than that of the longitudinal wave, we are able to achieve the high resolution by using transverse waves. In order to operate SLAM in the transverse wave mode, we made wedge for changing the incident angle. Our experimental results with model 2140 SLAM and an aluminum specimen showed higher contrast of the SLAM Image In the transverse wave mode than that in the longitudinal wave mode.

  20. Longitudinal and transverse wake potentials in SLAC

    International Nuclear Information System (INIS)

    Bane, K.; Wilson, P.

    1980-01-01

    In a machine with short bunches of high peak currents, such as the SLAC collider, one needs to know the longitudinal wake potential, for the higher mode losses, and the transverse wake potential, since, for bunches passing slightly off axis, the induced transverse forces will tend to cause beam break up. The longitudinal and transverse wakes of the SLAC structure presented here, were calculated by computer using the modal method, and including an analytic extension for higher modes. (Auth.)

  1. Laparoscopic colectomy for transverse colon carcinoma.

    Science.gov (United States)

    Zmora, O; Bar-Dayan, A; Khaikin, M; Lebeydev, A; Shabtai, M; Ayalon, A; Rosin, D

    2010-03-01

    Laparoscopic resection of transverse colon carcinoma is technically demanding and was excluded from most of the large trials of laparoscopic colectomy. The aim of this study was to assess the safety, feasibility, and outcome of laparoscopic resection of carcinoma of the transverse colon. A retrospective review was performed to identify patients who underwent laparoscopic resection of transverse colon carcinoma. These patients were compared to patients who had laparoscopic resection for right and sigmoid colon carcinoma. In addition, they were compared to a historical series of patients who underwent open resection for transverse colon cancer. A total of 22 patients underwent laparoscopic resection for transverse colon carcinoma. Sixty-eight patients operated for right colon cancer and 64 operated for sigmoid colon cancer served as comparison groups. Twenty-four patients were identified for the historical open group. Intraoperative complications occurred in 4.5% of patients with transverse colon cancer compared to 5.9% (P = 1.0) and 7.8% (P = 1.0) of patients with right and sigmoid colon cancer, respectively. The early postoperative complication rate was 45, 50 (P = 1.0), and 37.5% (P = 0.22) in the three groups, respectively. Conversion was required in 1 (5%) patient in the laparoscopic transverse colon group. The conversion rate and late complications were not significantly different in the three groups. There was no significant difference in the number of lymph nodes harvested in the laparoscopic and open groups. Operative time was significantly longer in the laparoscopic transverse colectomy group when compared to all other groups (P = 0.001, 0.008, and transverse colectomy, respectively). The results of laparoscopic colon resection for transverse colon carcinoma are comparable to the results of laparoscopic resection of right or sigmoid colon cancer and open resection of transverse colon carcinoma. These results suggest that laparoscopic resection of transverse

  2. Large transverse momentum behavior of gauge theories

    International Nuclear Information System (INIS)

    Coquereaux, Robert; De Rafael, Eduardo.

    1977-05-01

    The large transverse momentum behavior of Compton scattering and Moeller scattering in Quantum Electrodynamics; and of elastic quark-quark scattering in Quantum Chromodynamics are examined in perturbation theory. The results strongly suggest that the large transverse momentum regime in gauge theories is governed by a differential equation of the Callan-Symanzik type with a suitable momentum dependent anomalous dimension term. An explicit solution for the quark-quark elastic scattering amplitude at large transverse momentum is given

  3. Deuteron transverse densities in holographic QCD

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Chandan [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China); Indian Institute of Technology Kanpur, Department of Physics, Kanpur (India); Chakrabarti, Dipankar [Indian Institute of Technology Kanpur, Department of Physics, Kanpur (India); Zhao, Xingbo [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China)

    2017-05-15

    We investigate the transverse charge density in the longitudinally as well as transversely polarized deuteron using the recent empirical description of the deuteron electromagnetic form factors in the framework of holographic QCD. The predictions of the holographic QCD are compared with the results of a standard phenomenological parameterization. In addition, we evaluate GPDs and the gravitational form factors for the deuteron. The longitudinal momentum densities are also investigated in the transverse plane. (orig.)

  4. Acoustic ambient noise recorder

    Digital Repository Service at National Institute of Oceanography (India)

    Saran, A.K.; Navelkar, G.S.; Almeida, A.M.; More, S.R.; Chodankar, P.V.; Murty, C.S.

    with a robust outfit that can withstand high pressures and chemically corrosion resistant materials. Keeping these considerations in view, a CMOS micro-controller-based marine acoustic ambient noise recorder has been developed with a real time clock...

  5. The effect of gradational velocities and anisotropy on fault-zone trapped waves

    Science.gov (United States)

    Gulley, A. K.; Eccles, J. D.; Kaipio, J. P.; Malin, P. E.

    2017-08-01

    Synthetic fault-zone trapped wave (FZTW) dispersion curves and amplitude responses for FL (Love) and FR (Rayleigh) type phases are analysed in transversely isotropic 1-D elastic models. We explore the effects of velocity gradients, anisotropy, source location and mechanism. These experiments suggest: (i) A smooth exponentially decaying velocity model produces a significantly different dispersion curve to that of a three-layer model, with the main difference being that Airy phases are not produced. (ii) The FZTW dispersion and amplitude information of a waveguide with transverse-isotropy depends mostly on the Shear wave velocities in the direction parallel with the fault, particularly if the fault zone to country-rock velocity contrast is small. In this low velocity contrast situation, fully isotropic approximations to a transversely isotropic velocity model can be made. (iii) Fault-aligned fractures and/or bedding in the fault zone that cause transverse-isotropy enhance the amplitude and wave-train length of the FR type FZTW. (iv) Moving the source and/or receiver away from the fault zone removes the higher frequencies first, similar to attenuation. (v) In most physically realistic cases, the radial component of the FR type FZTW is significantly smaller in amplitude than the transverse.

  6. Scanning anisotropy parameters in horizontal transversely isotropic media

    KAUST Repository

    Masmoudi, Nabil

    2016-10-12

    The horizontal transversely isotropic model, with arbitrary symmetry axis orientation, is the simplest effective representative that explains the azimuthal behaviour of seismic data. Estimating the anisotropy parameters of this model is important in reservoir characterisation, specifically in terms of fracture delineation. We propose a travel-time-based approach to estimate the anellipticity parameter η and the symmetry axis azimuth ϕ of a horizontal transversely isotropic medium, given an inhomogeneous elliptic background model (which might be obtained from velocity analysis and well velocities). This is accomplished through a Taylor\\'s series expansion of the travel-time solution (of the eikonal equation) as a function of parameter η and azimuth angle ϕ. The accuracy of the travel time expansion is enhanced by the use of Shanks transform. This results in an accurate approximation of the solution of the non-linear eikonal equation and provides a mechanism to scan simultaneously for the best fitting effective parameters η and ϕ, without the need for repetitive modelling of travel times. The analysis of the travel time sensitivity to parameters η and ϕ reveals that travel times are more sensitive to η than to the symmetry axis azimuth ϕ. Thus, η is better constrained from travel times than the azimuth. Moreover, the two-parameter scan in the homogeneous case shows that errors in the background model affect the estimation of η and ϕ differently. While a gradual increase in errors in the background model leads to increasing errors in η, inaccuracies in ϕ, on the other hand, depend on the background model errors. We also propose a layer-stripping method valid for a stack of arbitrary oriented symmetry axis horizontal transversely isotropic layers to convert the effective parameters to the interval layer values.

  7. Evolution of the helicity and transversity Transverse-Momentum-Dependent parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Prokudin, Alexei [JLAB; Bacchetta, Alessandro [INFN-PAVIA

    2013-07-01

    We examine the QCD evolution of the helicity and transversity parton distribution functions when including also their dependence on transverse momentum. Using an appropriate definition of these polarized transverse momentum distributions (TMDs), we describe their dependence on the factorization scale and rapidity cutoff, which is essential for phenomenological applications.

  8. No generalized transverse momentum dependent factorization in the hadroproduction of high transverse momentum hadrons

    NARCIS (Netherlands)

    Rogers, T.C.; Mulders, P.J.G.

    2010-01-01

    It has by now been established that standard QCD factorization using transverse momentum dependent parton distribution functions fails in hadroproduction of nearly back-to-back hadrons with high transverse momentum. The essential problem is that gauge-invariant transverse momentum dependent parton

  9. Transverse momentum distributions of identified particles produced ...

    Indian Academy of Sciences (India)

    We assume that the transverse momentum distributions of identified particles measured in final state are contributed by a few energy sources which can be regarded as partons or quarks in the interacting system. The particle is contributed by each source with gluons which have transverse momentum distributions in an ...

  10. Transverse spin and momentum correlations in quantum ...

    Indian Academy of Sciences (India)

    These transverse momentum-dependent parton distribution functions are of significance for the analysis of azimuthal asymmetries in semi-inclusive deep inelastic scattering, as well as for the overall physical understanding of the distribution of transversely polarized quarks in unpolarized hadrons. In this context we also ...

  11. Average Transverse Momentum Quantities Approaching the Lightfront

    NARCIS (Netherlands)

    Boer, Daniel

    In this contribution to Light Cone 2014, three average transverse momentum quantities are discussed: the Sivers shift, the dijet imbalance, and the p (T) broadening. The definitions of these quantities involve integrals over all transverse momenta that are overly sensitive to the region of large

  12. Transverse spin and momentum correlations in quantum ...

    Indian Academy of Sciences (India)

    Collaboration [2] describes correlations of the intrinsic quark transverse momen- tum and the transverse nucleon ..... These results are in agreement with the large Nc predictions [41], Bag. Model results reported in [42], ..... work is supported by a grant from the US Department of Energy under contract. DE-FG02-07ER41460.

  13. Anaesthetic considerations in patients with transverse myelitis ...

    African Journals Online (AJOL)

    Transverse myelitis is an acute or subacute inflammatory disorder involving the spinal cord. Clinical signs are due to the involvement of the ascending and descending tracts in the transverse plane of the spinal cord. The most common cause is autoimmune. These patients may present with various clinical findings with ...

  14. MRI in acute transverse myelopathy

    Energy Technology Data Exchange (ETDEWEB)

    Holtaas, S. (Dept. of Diagnostic Radiology, Univ. Hospital Lund (Sweden)); Basibueyuek, N. (Dept. of Diagnostic Radiology, Univ. Hospital Lund (Sweden)); Fredriksson, K. (Dept. of Neurology, Univ. Hospital Lund (Sweden))

    1993-03-01

    The MRI examinations of seven patients with acute transverse myelopathy (ATM) were analysed. The patients were examined 2-5 times during the course of their disease with short and long TR/TE spin-echo sequences in the sagittal projection. A previous history of autoimmune disorder and/or signs of infection at the onset of ATM were present in all cases. Cerebrospinal fluid analysis showed local synthesis of immunoglobulin in the nervours system in three cases and signs of infectious myelitis in one. During the acute phase four patients had local enlargement of the cord and all had increased signal on long TR/TE sequences. The outcome was grave in the majority of patients and there seemed to be a correlation between the degree of cord enlargement, persistence of increased signal intensity and limited recovery. Atrophy and remaining high signal intensity were noted on late MRI patients with poor outcome. In one patient with probable anterior spinal artery occlusion, cavitation of the cord was seen. (orig.)

  15. Passage of radiation through moving astrophysical plasmas: The fresnel drag in transversely moving dispersive media

    International Nuclear Information System (INIS)

    Ko, H.C.

    1979-01-01

    The problem of upstream bending of light beam in transversely moving dispersive media is investigated in general terms, without using specific physical models of the media. It is shown that npartial (ω'n)/partialω' ω/sub p/ (/sub X/T/mc 2 )/sup 1/2/. The formula is therefore not expected to satisfy the Kramers-Kroenig relations which require a complete knowledge of n 2 at all frequencies 0< or =ω'< or =infinity. The question of the group velocity as a representation of the direction and the speed of energy flow for steady quasi-monochromatic radiation is discussed. The distinction between the group velocity and the packet velocity is explained. It is also shown that, contrary to common belief, in moving dispersive media the direction of the group velocity does not coincide with that of the Poynting vector. However, the direction of the group velocity coincides with that of the total energy flux

  16. Transverse spin dependent azimuthal asymmetries at COMPASS

    CERN Document Server

    Parsamyan, Bakur

    2011-01-01

    In semi-inclusive deep inelastic scattering of polarized leptons on a transversely polarized target eight target transverse spin-dependent azimuthal modulations are allowed. In the QCD parton model half of these asymmetries can be interpreted within the leading order approach and the other four are twist-three contributions. The first two leading twist asymmetries extracted by HERMES and COMPASS experiments are related: one to the transversity distribution and the Collins effect, the other to the Sivers distribution function. These results triggered a lot of interest in the past few years and allowed the first extractions of the transversity and the Sivers distribution functions of nucleon. The remaining six asymmetries were obtained by the COMPASS experiment using a 160 GeV/c longitudinally polarized muon beam and transversely polarized deuteron and proton targets. Here we review preliminary results from COMPASS proton data of 2007.

  17. The transverse acetabular ligament: optimizing version.

    Science.gov (United States)

    Beverland, David

    2010-09-07

    In total hip arthroplasty (THA), excessive retroversion is associated with posterior instability, anterior impingement, and resultant groin pain. Excessive anteversion can lead to anterior instability and posterior impingement. The transverse acetabular ligament straddles the inferior limit of the bony acetabulum. It is a strong load-bearing structure and, in the normal hip, in association with the labrum, provides part of the load-bearing surface for the femoral head. It is our hypothesis that the transverse acetabular ligament defines normal version for the acetabulum. In Belfast, we found that using the transverse acetabular ligament helped reduce our primary dislocation rate from 3.7% to 1%. The key is good intraoperative exposure. A grading of 1 to 4 was based on 1000 consecutive cases: (1) normal transverse acetabular ligament easily visible on exposure of the acetabulum, 49%; (2) covered by soft tissue, 35.1%--cleared by blunt dissection; (3) covered by osteophytes, 15.6%--cleared using an acetabular reamer; (4) no transverse acetabular ligament identified, 0.3%. As can be seen, the transverse acetabular ligament is only immediately visible in 49% of cases. In the other 51%, soft tissue or bone must be cleared to define the ligament. The advantages of the transverse acetabular ligament are many. It is independent of patient positioning. The cup version can be individualized by the patient. The surgeon can avoid estimating version angle of 15° to 20° intraoperatively. It is easy to teach and consistently present. It is valuable in minimally invasive surgery. Using the transverse acetabular ligament provides an acceptable dislocation rate with the posterior approach. If the cup is cradled by the transverse acetabular ligament, it helps restore acetabular joint center. However, the transverse acetabular ligament does not help with inclination. We recommend 35° of operative inclination when using the posterior approach. Copyright 2010, SLACK Incorporated.

  18. An investigation of ambient gameplay

    OpenAIRE

    Eyles, Mark

    2012-01-01

    Inspired by Brian Eno's ambient music, which is persistent and supports different levels of engagement, this research explores ambient gameplay in computer, video and pervasive games. Through the creation of original games containing ambient gameplay and looking for ambient gameplay in existing commercial games, this research focuses on gameplay that supports a range of depths of player engagement. This research is not concerned with ambient intelligent environments or other technologies that...

  19. Estimation of Continuous Velocity Model Variations in Rock Deformation Tests.

    Science.gov (United States)

    Flynn, J. W.; Tomas, R.; Benson, P. M.

    2017-12-01

    Seismic interferometry, using either seismic waves coda or ambient noise, is a passive technique to image the sub-surface seismic velocity structure, which directly relates to the physical properties of the material through which they travel. The methodology estimates the Green's function for the volume between two seismic stations by cross-correlating long time series of ambient noise recorded at both stations, with the Green's function being effectively the seismogram recorded at one station due to an impulsive or instantaneous energy source at the second station. In laboratory rock deformation experiments, changes in the velocity structure of the rock sample are generally measured through active surveys using an array of AE piezoelectric P-wave transducers, producing a time series of ultrasonic velocities in both axial and radial directions. The velocity information from the active surveys is used to provide a time dependent velocity model for the inversion of AE event source locations. These velocity measurements are carried out at regular intervals throughout the laboratory test, causing the interruption of passive AE monitoring for the length of the surveys. There is therefore a trade-off between the frequency at which the active velocity surveys are carried out to optimise the velocity model and the availability of a complete AE record during the rock deformation test.This study proposes to use noise interferometry to provide a continuous measurement of velocity variations in a rock sample during a laboratory rock deformation experiment without the need to carry out active velocity surveys while simultaneously passively monitoring AE activity. The continuous noise source in this test, is an AE transducer fed with a white gaussian noise signal from a function generator. Data from all AE transducers is continuously acquired and recorded during the deformation experiment. The cross correlation of the continuous AE record is used to produce a continuous velocity

  20. 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)

  1. Antarctic Ice Velocity Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This compilation of recent ice velocity data of the Antarctic ice sheet is intended for use by the polar scientific community. The data are presented in tabular form...

  2. 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.

  3. Influence of transverse reinforcement on perforation resistance of reinforced concrete slabs under hard missile impact

    Energy Technology Data Exchange (ETDEWEB)

    Orbovic, Nebojsa, E-mail: nebojsa.orbovic@cnsc-ccsn.gc.ca; Sagals, Genadijs; Blahoianu, Andrei

    2015-12-15

    This paper describes the work conducted by the Canadian Nuclear Safety Commission (CNSC) related to the influence of transverse reinforcement on perforation capacity of reinforced concrete (RC) slabs under “hard” missile impact (impact with negligible missile deformations). The paper presents the results of three tests on reinforced concrete slabs conducted at VTT Technical Research Centre (Finland), along with the numerical simulations as well as a discussion of the current code provisions related to impactive loading. Transverse reinforcement is widely used for improving the shear and punching strength of concrete structures. However, the effect of this reinforcement on the perforation resistance under localized missile impact is still unclear. The goal of this paper is to fill the gap in the current literature related to this topic. Based on similar tests designed by the authors with missile velocity below perforation velocity, it was expected that transverse reinforcement would improve the perforation resistance. Three slabs were tested under almost identical conditions with the only difference being the transverse reinforcement. One slab was designed without transverse reinforcement, the second one with the transverse reinforcement in form of conventional stirrups with hooks and the third one with the transverse reinforcement in form of T-headed bars. Although the transverse reinforcement reduced the overall damage of the slabs (the rear face scabbing), the conclusion from the tests is that the transverse reinforcement does not have important influence on perforation capacity of concrete slabs under rigid missile impact. The slab with T-headed bars presented a slight improvement compared to the baseline specimen without transverse reinforcement. The slab with conventional stirrups presented slightly lower perforation capacity (higher residual missile velocity) than the slab without transverse reinforcement. In conclusion, the performed tests show slightly

  4. Ambient oxygen promotes tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Ho Joong Sung

    2011-05-01

    Full Text Available Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a ∼50% increase in the median tumor-free survival time of p53-/- mice. In the thymus, reducing oxygen exposure decreased the levels of oxidative DNA damage and RAG recombinase, both of which are known to promote lymphomagenesis in p53-/- mice. Oxygen is further shown to be associated with genomic instability in two additional cancer models involving the APC tumor suppressor gene and chemical carcinogenesis. Together, these observations represent the first report directly testing the effect of ambient oxygen on de novo tumorigenesis and provide important physiologic evidence demonstrating its critical role in increasing genomic instability in vivo.

  5. El ambiente social

    Directory of Open Access Journals (Sweden)

    Henry Granada

    2001-01-01

    Full Text Available Con el título de« Ambiente Social» se quiere enfatizar que el concepto de Ambiente no se agota en lo ecológico (físico-biótico. Así mismo, dentro lo psicosocial, la noción de territorio adquiere importancia y otorga significación a la «experiencia ambiental», ya que abre ventanas hacia la comprensión de actividades como el ordenamiento territorial y a la mediación de las dimensiones psicológica, social y cultural del espacio. Finalmente, aunque el ordenamiento del territorio suele enfocarse desde los componentes sociopolíticos y económicos con el ánimo de planificación, el componente psicosocial traduce aspectos del ordenamiento dentro de la vida cotidiana y relaciona nociones como identidad y arraigo, entre otras.

  6. Slip velocity of large neutrally buoyant particles in turbulent flows

    International Nuclear Information System (INIS)

    Bellani, G; Variano, E A

    2012-01-01

    We discuss possible definitions for a stochastic slip velocity that describes the relative motion between large particles and a turbulent flow. This definition is necessary because the slip velocity used in the standard drag model fails when particle size falls within the inertial subrange of ambient turbulence. We propose two definitions, selected in part due to their simplicity: they do not require filtration of the fluid phase velocity field, nor do they require the construction of conditional averages on particle locations. A key benefit of this simplicity is that the stochastic slip velocity proposed here can be calculated equally well for laboratory, field and numerical experiments. The stochastic slip velocity allows the definition of a Reynolds number that should indicate whether large particles in turbulent flow behave (a) as passive tracers; (b) as a linear filter of the velocity field; or (c) as a nonlinear filter to the velocity field. We calculate the value of stochastic slip for ellipsoidal and spherical particles (the size of the Taylor microscale) measured in laboratory homogeneous isotropic turbulence. The resulting Reynolds number is significantly higher than 1 for both particle shapes, and velocity statistics show that particle motion is a complex nonlinear function of the fluid velocity. We further investigate the nonlinear relationship by comparing the probability distribution of fluctuating velocities for particle and fluid phases. (paper)

  7. 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.

  8. Ambiente, patrimonio y turismo

    OpenAIRE

    Mantero, Juan Carlos

    2003-01-01

    El tema de la conferencia asignado por los responsables del Tercer Congreso Latinoamericano de Investigación Turística supuso asumir la problemática de la interacción ambiente patrimonio turismo para realizar una reflexión que a partir de la definición de tales nociones permitiera acceder a una reflexión respecto de su significación cultural en la comunidad. El patrimonio de la comunidad comprende el ambiente e incluye la naturaleza y la cultura, del ayer y del presente, en su dimensión tangi...

  9. Ferroelectric Cathodes in Transverse Magnetic Fields

    International Nuclear Information System (INIS)

    Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch

    2002-01-01

    Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode

  10. Scaling properties of the transverse mass spectra

    International Nuclear Information System (INIS)

    Schaffner-Bielich, J.

    2002-01-01

    Motivated from the formation of an initial state of gluon-saturated matter, we discuss scaling relations for the transverse mass spectra at BNL's relativistic heavy-ion collider (RHIC). We show on linear plots, that the transverse mass spectra for various hadrons can be described by an universal function in m t . The transverse mass spectra for different centralities can be rescaled into each other. Finally, we demonstrate that m t -scaling is also present in proton-antiproton collider data and compare it to m t -scaling at RHIC. (orig.)

  11. Meio ambiente e literatura

    Directory of Open Access Journals (Sweden)

    Marli de Oliveira Fantini Scarpelli

    2007-06-01

    Full Text Available Este artigo busca reconhecer alguns pontos de tangência entre os romances Vidas secas, de Graciliano Ramos, As cidades invisíveis, de Italo Calvino, e Grande sertão: veredas, de Guimarães Rosa, sobretudo no que respeita às relações modalizantes entre literatura e meio ambiente. Em meio à diversidade temática das obras indicadas, subjaz o tema da consciência ambiental, que, nas últimas décadas, vem recebendo a crescente adesão não apenas de ambientalistas, mas também de intelectuais, políticos, escritores. O foco na degradação ambiental, no alerta implícito acerca das precárias condições de vida futura em nosso planeta revela um dos nucleares e contundentes problemas a desafiar a agenda contemporânea. Nesse sentido, revela-se paradigmático o “lugar-sertão” rosiano, que, ao difundir seu território, seus valores e denúncias, patenteia uma concepção ambiental inovadora e reticular, em estreito diálogo com as atuais pesquisas interdisciplinares sobre o tema, as quais deveriam doravante guardar, em seu horizonte de expectativa, os paradigmas, as perspectivas e os equacionamentos que alicerçam as artes em geral e a literatura em particular.

  12. 3-D Velocity Estimation for Two Planes in vivo

    DEFF Research Database (Denmark)

    Holbek, Simon; Pihl, Michael Johannes; Ewertsen, Caroline

    2014-01-01

    3-D velocity vectors can provide additional flow information applicable for diagnosing cardiovascular diseases e.g. by estimating the out-of-plane velocity component. A 3-D version of the Transverse Oscillation (TO) method has previously been used to obtain this information in a carotid flow....... In the longitudinal plane, average maximum peak velocity in flow direction was 65.2 14.0 cm/s at peak-systole and 33.6 4.3 cm/s at end-diastole. A commercial BK Medical ProFocus UltraView scanner using a spectral estimator gave 79.3 cm/s and 14.6 cm/s for the same volunteer. This demonstrates that real-time 3-D...... vector velocity imaging without ECG gating yields quantitative in vivo estimations on flow direction and magnitude...

  13. Recent advances in blood flow vector velocity imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav; Udesen, Jesper

    2011-01-01

    been acquired using a commercial implementation of the method (BK Medical ProFocus Ultraview scanner). A range of other methods are also presented. This includes synthetic aperture imaging using either spherical or plane waves with velocity estimation performed with directional beamforming or speckle...... Medical 8804 transducer. This resulted in a relative standard deviation of 1.2% for a fully transverse flow. Plane wave imaging was also implemented on the RASMUS scanner and a 100 Hz frame rate was attained. Several vector velocity image sequences of complex flow were acquired, which demonstrates...

  14. Constituent models and large transverse momentum reactions

    International Nuclear Information System (INIS)

    Brodsky, S.J.

    1975-01-01

    The discussion of constituent models and large transverse momentum reactions includes the structure of hard scattering models, dimensional counting rules for large transverse momentum reactions, dimensional counting and exclusive processes, the deuteron form factor, applications to inclusive reactions, predictions for meson and photon beams, the charge-cubed test for the e/sup +-/p → e/sup +-/γX asymmetry, the quasi-elastic peak in inclusive hadronic reactions, correlations, and the multiplicity bump at large transverse momentum. Also covered are the partition method for bound state calculations, proofs of dimensional counting, minimal neutralization and quark--quark scattering, the development of the constituent interchange model, and the A dependence of high transverse momentum reactions

  15. Transverse steering of two-component beams

    International Nuclear Information System (INIS)

    Murin, B.P.; Bondarev, B.U.; Durkin, A.P.; Lomize, L.G.; Soloviev, L.Yu.; Fedotov, A.P.

    Coherent transverse oscillations are considered which occur during simultaneous acceleration of proton and H - beams due to arbitrary displacements in elements of the focusing channel. To suppress these oscillations, a beam adjustment station is proposed, in which each quadrupole lens of two doublets is provided with a special dipole component of the magnetic field. These steering elements, together with the beam transverse position monitors, permit steering the transverse position of beams of opposite signs in both transverse planes. The number of steering stations needed is chosen, and some algorithms for control are discussed. It is shown that some of the control algorithms will permit not only the suppression of coherent oscillations, but a decrease in the radius and emittance of the beam

  16. Velocity pump reaction turbine

    Science.gov (United States)

    House, P.A.

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

  17. 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...... description of this momentum flow. The Prescribed Velocity Method is a practical method for the description of an Air Terminal Device which will save grid points close to the opening and ensure the right level of the momentum flow....

  18. Elliptic flow coefficients from transverse momentum conservation

    Science.gov (United States)

    Bzdak, Adam; Ma, Guo-Liang

    2018-01-01

    We calculate the k -particle (k =2 ,4 ,6 ,8 ) azimuthal cumulants resulting from the conservation of transverse momentum. We find that c2{k } >0 and, depending on the transverse momenta, c2{k } can reach substantial values even for a relatively large number of particles. The impact of our results on the understanding of the onset of collectivity in small systems is emphasized.

  19. Parametric Transverse Patterns in Broad Aperture Lasers

    DEFF Research Database (Denmark)

    Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik

    1998-01-01

    Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence on the geo......Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence...

  20. Chiral dynamics and peripheral transverse densities

    Energy Technology Data Exchange (ETDEWEB)

    Granados, Carlos G. [Uppsala University (Sweden); Weiss, Christian [JLAB, Newport News, VA (United States)

    2014-01-01

    In the partonic (or light-front) description of relativistic systems the electromagnetic form factors are expressed in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral components of nucleon structure as the peripheral densities at transverse distances b = O(M{sub {pi}}{sup -1}) and compute them in a parametrically controlled manner. A dispersion relation connects the large-distance behavior of the transverse charge and magnetization densities to the spectral functions of the Dirac and Pauli form factors near the two--pion threshold at timelike t = 4 M{ sub {pi}}{sup 2}, which can be computed in relativistic chiral effective field theory. Using the leading-order approximation we (a) derive the asymptotic behavior (Yukawa tail) of the isovector transverse densities in the "chiral" region b = O(M{sub {pi}}{sup -1}) and the "molecular" region b = O(M{sub N}{sup 2}/M{sub {pi}}{sup 3}); (b) perform the heavy-baryon expansion of the transverse densities; (c) explain the relative magnitude of the peripheral charge and magnetization densities in a simple mechanical picture; (d) include Delta isobar intermediate states and study the peripheral transverse densities in the large-N{ sub c} limit of QCD; (e) quantify the region of transverse distances where the chiral components of the densities are numerically dominant; (f) calculate the chiral divergences of the b{sup 2}-weighted moments of the isovector transverse densities (charge and anomalous magnetic radii) in the limit M{sub {pi}} -> 0 and determine their spatial support. Our approach provides a concise formulation of the spatial structure of the nucleon's chiral component and offers new insights into basic properties of the chiral expansion. It relates the information extracted from low-t elastic form factors to the generalized parton distributions probed in peripheral high-energy scattering processes.

  1. Transverse angular momentum in topological photonic crystals

    Science.gov (United States)

    Deng, Wei-Min; Chen, Xiao-Dong; Zhao, Fu-Li; Dong, Jian-Wen

    2018-01-01

    Engineering local angular momentum of structured light fields in real space enables applications in many fields, in particular, the realization of unidirectional robust transport in topological photonic crystals with a non-trivial Berry vortex in momentum space. Here, we show transverse angular momentum modes in silicon topological photonic crystals when considering transverse electric polarization. Excited by a chiral external source with either transverse spin angular momentum or transverse phase vortex, robust light flow propagating along opposite directions is observed in several kinds of sharp-turn interfaces between two topologically-distinct silicon photonic crystals. A transverse orbital angular momentum mode with alternating phase vortex exists at the boundary of two such photonic crystals. In addition, unidirectional transport is robust to the working frequency even when the ring size or location of the pseudo-spin source varies in a certain range, leading to the superiority of the broadband photonic device. These findings enable one to make use of transverse angular momentum, a kind of degree of freedom, to achieve unidirectional robust transport in the telecom region and other potential applications in integrated photonic circuits, such as on-chip robust delay lines.

  2. Transverse structure of the QCD string

    International Nuclear Information System (INIS)

    Meyer, Harvey B.

    2010-01-01

    The characterization of the transverse structure of the QCD string is discussed. We formulate a conjecture as to how the stress-energy tensor of the underlying gauge theory couples to the string degrees of freedom. A consequence of the conjecture is that the energy density and the longitudinal-stress operators measure the distribution of the transverse position of the string, to leading order in the string fluctuations, whereas the transverse-stress operator does not. We interpret recent numerical measurements of the transverse size of the confining string and show that the difference of the energy and longitudinal-stress operators is a particularly natural probe at next-to-leading order. Second, we derive the constraints imposed by open-closed string duality on the transverse structure of the string. We show that a total of three independent ''gravitational'' form factors characterize the transverse profile of the closed string, and obtain the interpretation of recent effective string theory calculations: the square radius of a closed string of length β defined from the slope of its gravitational form factor, is given by (d-1/2πσ)log(β/4r 0 ) in d space dimensions. This is to be compared with the well-known result that the width of the open string at midpoint grows as (d-1/2πσ)log(r/r 0 ). We also obtain predictions for transition form factors among closed-string states.

  3. A Study of Large Transverse Momentum Phenomena

    CERN Multimedia

    2002-01-01

    This experiment studies the structure of those p-p and @*-p collisions which are characterized by a very high transverse momentum flow in the central region. Some specific items studied are:\\\\ \\\\ \\item -~~Structure of events, where the high transverse momentum is shared by charged and neutral hadron (``jets''). Transverse momentum distribution, correlations and momentum balance for such events. \\item -~~Structure of events, where the high transverse momentum is mostly carried by one identified particle. Quantum number dependence and quantum number correlations of the high transverse momentum events. \\item -~~Structure of events containing large transverse momentum leptons or lepton pairs or direct photons. \\end{enumerate}.sk -~~Study of low momentum electrons and photons. -~~Search for gluonium states. -~~Search for new and rare particles. \\\\ \\\\ A conventional C-type magnet with a 0.5 T field in the direction of the beams together with a 42-layer cylindrical drift chamber detector is used for momentum analysi...

  4. Evaluation of the photocathode laser transverse distribution

    Energy Technology Data Exchange (ETDEWEB)

    Saisa-ard, Chaipattana [DESY, Zeuthen (Germany); Chiang Mai Univ., Chiang Mai (Thailand); Krasilnikov, Mikhail; Vashchenko, Grygorii [DESY, Zeuthen (Germany)

    2016-07-01

    Many years experience of electron source developments at the photo injector test facility at DESY in Zeuthen (PITZ) show that the photocathode laser is the one of major tools to produce high brightness electron beams. The transverse distribution of the laser on the photocathode plays a significant role in the high brightness photo injector optimization. However, the imperfections in the laser beam profile according to the deviation from a radially homogeneous profile directly result in transversely distorted charged particle distributions. This includes inhomogeneous core as well as transverse halo which is due to not sharp edges around the core. The laser transverse distribution is measured at PITZ using a virtual cathode:this is a CCD camera located at the position which is optically equivalent to the photocathode position (so called virtual cathode). An algorithm is developed for the evaluation of the experimentally obtained transverse profiles. It fits a flat-top or an inhomogeneous rotational symmetric core with exponentially decaying tails to an experimental distribution. The MATLAB script with implemented algorithm is applied to a set of measured transverse laser distributions. Results of the analysis will be presented.

  5. Gap-junction channels inhibit transverse propagation in cardiac muscle

    Directory of Open Access Journals (Sweden)

    Ramasamy Lakshminarayanan

    2005-01-01

    Full Text Available Abstract The effect of adding many gap-junctions (g-j channels between contiguous cells in a linear chain on transverse propagation between parallel chains was examined in a 5 × 5 model (5 parallel chains of 5 cells each for cardiac muscle. The action potential upstrokes were simulated using the PSpice program for circuit analysis. Either a single cell was stimulated (cell A1 or the entire chain was stimulated simultaneously (A-chain. Transverse velocity was calculated from the total propagation time (TPT from when the first AP crossed a Vm of -20 mV and the last AP crossed -20 mV. The number of g-j channels per junction was varied from zero to 100, 1,000 and 10,000 (Rgj of ∞, 100 MΩ, 10 MΩ, 1.0 MΩ, respectively. The longitudinal resistance of the interstitial fluid (ISF space between the parallel chains (Rol2 was varied between 200 KΩ (standard value and 1.0, 5.0, and 10 MΩ. The higher the Rol2 value, the tighter the packing of the chains. It was found that adding many g-j channels inhibited transverse propagation by blocking activation of all 5 chains, unless Rol2 was greatly increased above the standard value of 200 KΩ. This was true for either method of stimulation. This was explained by, when there is strong longitudinal coupling between all 5 cells of a chain awaiting excitation, there must be more transfer energy (i.e., more current to simultaneously excite all 5 cells of a chain.

  6. Reverse time migration in tilted transversely isotropic media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Linbing; Rector III, James W.; Hoversten, G. Michael

    2004-07-01

    This paper presents a reverse time migration (RTM) method for the migration of shot records in tilted transversely isotropic (TTI) media. It is based on the tilted TI acoustic wave equation that was derived from the dispersion relation. The RTM is a full depth migration allowing for velocity to vary laterally as well as vertically and has no dip limitations. The wave equation is solved by a tenth-order finite difference scheme. Using 2D numerical models, we demonstrate that ignoring the tilt angle will introduce both lateral and vertical shifts in imaging. The shifts can be larger than 0.5 wavelength in the vertical direction and 1.5 wavelength in the lateral direction.

  7. Indicadores de salud ambiental

    Directory of Open Access Journals (Sweden)

    Manuel Posada de la Paz

    2004-12-01

    Full Text Available Esta ponencia presenta una visión general del proyecto de Indicadores de Salud Ambiental, coordinado por la OMS a nivel internacional y liderado por el Centro de Investigación sobre el Síndrome del Aceite Tóxico y Enfermedades Raras (CISATER en España. En ella se describen los objetivos del proyecto, las gestiones realizadas y los resultados obtenidos durante la fase de viabilidad de este proyecto. El proyecto consiste en el establecimiento de un sistema de información sobre salud ambiental que permita desarrollar una vigilancia de los factores ambientales determinantes de los estados de salud, realizar comparaciones internacionales, elaborar políticas de acción, así como facilitar la comunicación con la ciudadanía. La OMS desarrolló una metodología para el desarrollo de estos indicadores dentro del marco conceptual de información ambiental DPSEEA (Fuerzas impulsoras, Presión, Estado, Exposición, Efecto, Acción y seleccionó un total de 55 indicadores (que incluyen 168 variables sobre 10 áreas de la salud ambiental. Durante la fase de viabilidad se predijo que podrían obtenerse el 89% de los indicadores. Sin embargo la recolección de los datos supuso muchas dificultades debido a la incompatibilidad de algunas variables en los sistemas de información españoles con las variables definidas por la OMS. A nivel de gestión del proyecto, la mayor dificultad radica en la disparidad de responsabilidades en materia de medio ambiente y salud entre las instituciones españolas. Además de la aportación técnica a la salud ambiental en España, un valor añadido de este proyecto ha sido el establecimiento de líneas de colaboración estrechas con los responsables de los diferentes Ministerios implicados.

  8. Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Office of Air and Radiation's (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

  9. Transverse forces on a vortex in lattice models of superfluids

    Science.gov (United States)

    Sonin, E. B.

    2013-12-01

    The paper derives the transverse forces (the Magnus and the Lorentz forces) in the lattice models of superfluids in the continuous approximation. The continuous approximation restores translational invariance absent in the original lattice model, but the theory is not Galilean invariant. As a result, calculation of the two transverse forces on the vortex, Magnus force and Lorentz force, requires the analysis of two balances, for the true momentum of particles in the lattice (Magnus force) and for the quasimomentum (Lorentz force) known from the Bloch theory of particles in the periodic potential. While the developed theory yields the same Lorentz force, which was well known before, a new general expression for the Magnus force was obtained. The theory demonstrates how a small Magnus force emerges in the Josephson-junction array if the particle-hole symmetry is broken. The continuous approximation for the Bose-Hubbard model close to the superfluid-insulator transition was developed, which was used for calculation of the Magnus force. The theory shows that there is an area in the phase diagram for the Bose-Hubbard model, where the Magnus force has an inverse sign with respect to that which is expected from the sign of velocity circulation.

  10. ENERGY CONTENT AND PROPAGATION IN TRANSVERSE SOLAR ATMOSPHERIC WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Van Doorsselaere, T. [Centre for mathematical Plasma Astrophysics, Mathematics Department, Celestijnenlaan 200B bus 2400, B-3001 Heverlee (Belgium); Soler, R. [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Verth, G., E-mail: tom.vandoorsselaere@wis.kuleuven.be [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield S3 7RH (United Kingdom)

    2013-05-10

    Recently, a significant amount of transverse wave energy has been estimated propagating along solar atmospheric magnetic fields. However, these estimates have been made with the classic bulk Alfven wave model which assumes a homogeneous plasma. In this paper, the kinetic, magnetic, and total energy densities and the flux of energy are computed for transverse MHD waves in one-dimensional cylindrical flux tube models with a piecewise constant or continuous radial density profile. There are fundamental deviations from the properties for classic bulk Alfven waves. (1) There is no local equipartition between kinetic and magnetic energy. (2) The flux of energy and the velocity of energy transfer have, in addition to a component parallel to the magnetic field, components in the planes normal to the magnetic field. (3) The energy densities and the flux of energy vary spatially, contrary to the case of classic bulk Alfven waves. This last property has the important consequence that the energy flux computed with the well known expression for bulk Alfven waves could overestimate the real flux by a factor in the range 10-50, depending on the flux tube equilibrium properties.

  11. The influence of gluteus maximus on transverse plane tibial rotation.

    Science.gov (United States)

    Preece, Stephen J; Graham-Smith, Philip; Nester, Chris J; Howard, Dave; Hermens, Hermie; Herrington, Lee; Bowker, Peter

    2008-05-01

    There is a common clinical belief that transverse plane tibial rotation is controlled by the rearfoot. Although distal structures may influence the motion of the tibia, transverse plane tibial rotation could be determined by the proximal hip musculature. Cadaver studies have identified gluteus maximus as having the largest capacity for external rotation of the hip. This study was therefore undertaken to investigate the effect of gluteus maximus on tibial motion. Kinematic data were collected from the foot and tibia along with EMG data from gluteus maximus for 17 male subjects during normal walking. A number of kinematic parameters were derived to characterise early stance phase. Gluteus maximus function was characterised using RMS EMG and EMG on/off times. No differences in muscle timing were found to be associated with any of the kinematic parameters. In addition, no differences in gluteal activation levels were found between groups of subjects who had different amounts of tibial rotation. However, there was a significant difference (pgluteus maximus activation when groups were defined by the time taken to decelerate the tibia (time to peak internal velocity). Specifically, subjects with greater gluteus maximus activity had a lower time to decelerate the tibia. We suggest that a high level of gluteus maximus activity results in a larger external torque being applied to the femur, which ultimately leads to a more rapid deceleration of the tibia.

  12. Ambient Noise Tomography at Regional and Local Scales in Southern California using Rayleigh Wave Phase Dispersion and Ellipticity

    Science.gov (United States)

    Berg, E.; Lin, F. C.; Qiu, H.; Wang, Y.; Allam, A. A.; Clayton, R. W.; Ben-Zion, Y.

    2017-12-01

    Rayleigh waves extracted from cross-correlations of ambient seismic noise have proven useful in imaging the shallow subsurface velocity structure. In contrast to phase velocities, which are sensitive to slightly deeper structure, Rayleigh wave ellipticity (H/V ratios) constrains the uppermost crust. We conduct Rayleigh wave ellipticity and phase dispersion measurements in Southern California between 6 and 18 second periods, computed from multi-component ambient noise cross-correlations using 315 stations across the region in 2015. Because of the complimentary sensitivity of phase velocity and H/V, this method enables simple and accurate resolution of near-surface geological features from the surface to 20km depth. We compare the observed H/V ratios and phase velocities to predictions generated from the current regional models (SCEC UCVM), finding strong correspondence where the near-surface structure is well-resolved by the models. This includes high H/V ratios in the LA Basin, Santa Barbara Basin and Salton Trough; and low ratios in the San Gabriel, San Jacinto and southern Sierra Nevada mountains. Disagreements in regions such as the Western Transverse Ranges, Salton Trough, San Jacinto and Elsinore fault zones motivate further work to improve the community models. A new updated 3D isotropic model of the area is derived via a joint inversion of Rayleigh phase dispersions and H/V ratios. Additionally, we examine azimuthal dependence of the H/V ratio to ascertain anisotropy patterns for each station. Clear 180º periodicity is observed for many stations suggesting strong shallow anisotropy across the region including up to 20% along the San Andreas fault, 15% along the San Jacinto Fault and 25% in the LA Basin. To better resolve basin structures, we apply similar techniques to three dense linear geophone arrays in the San Gabriel and San Bernardino basins. The three arrays are composed by 50-125 three-component 5Hz geophones deployed for one month each with 15-25km

  13. Nonlinear effects in the propagation of shortwave transverse sound in pure superconductors

    International Nuclear Information System (INIS)

    Gal'perin, Y.

    1982-01-01

    Various mechanisms are analyzed which lead to nonlinear phenomena (e.g., the dependence of the absorption coefficient and of the velocity of sound on its intensity) in the propagation of transverse shortwave sound in pure superconductors (the wavelength of the sound being much less than the mean free path of the quasiparticles). It is shown that the basic mechanism, over a wide range of superconductor parameters and of the sound intensity, is the so-called momentum nonlinearity. The latter is due to the distortion (induced by the sound wave) of the quasimomentum distribution of resonant electrons interacting with the wave. The dependences of the absorption coefficient and of the sound velocity on its intensity and on the temperature are analyzed in the vicinity of the superconducting transition point. The feasibility of an experimental study of nonlinear acoustic phenomena in the case of transverse sound is considered

  14. Planejamento ambiental do turismo

    OpenAIRE

    Clauciana Schmidt Bueno de Moraes

    2002-01-01

    O planejamento ambiental municipal através da metodologia elaborada nesta pesquisa visa contribuir para a adequação das características físico-ambientais, sócio-econômicas, político-administrativas e histórico-culturais do município relacionado com as atividades turísticas. Neste sentido, a conscientização voltada para a conservação através da educação ambiental se torna indispensável para organizar o espaço turístico, direcionado à importância de uma satisfação das necessidades das gerações ...

  15. MEIO AMBIENTE E DESENVOLVIMENTO

    Directory of Open Access Journals (Sweden)

    Suely Salgueiro Chacon

    2009-12-01

    Full Text Available O objetivo deste artigo é resgatar elementos para subsidiar uma reflexão crítica sobre o modelo de desenvolvimento econômico prevalente na sociedade e as relações com o meio ambiente, sob a ameaça que ronda o destino da espécie humana, conforme afirmação de Lovelock (2006, p. 20 sobre o conceito de desenvolvimento sustentável: “uma ideia adorável se a tivéssemos aplicado 200 anos atrás, quando havia um bilhão de pessoas no mundo. Agora é tarde demais. Não há mais espaço para nenhum tipo de desenvolvimento. A humanidade tem que regredir”. Este artigo apresenta a evolução do conceito de desenvolvimento econômico sob a ótica da sustentabilidade, e interliga temas como: o ambientalismo, aglutinador de distintos pensamentos sobre as relações entre a sociedade e a natureza; o movimento ambiental, a fundamentar a disseminação do conceito de desenvolvimento sustentável, e a gestão ambiental, abordada como prática orientada pelo conceito de desenvolvimento sustentável.

  16. Transient Simulation of a Rotating Conducting Cylinder in a Transverse Magnetic Field

    Science.gov (United States)

    2016-09-01

    field. The factors that affect the magnetic field inside the cylinder were analyzed by varying the spin rate and the electromagnetic physical ...Magnetic vector potential, Weber/meter (Wb/m) ?̅? - Magnetic flux density, tesla (T) ?̅? - Velocity, meter/second (m/s) or...immersed in a uniform transverse magnetic field by varying the spin rate (rpm) and electromagnetic physical properties [conductivity () and permeability

  17. The transverse and rotational motions of magnetohydrodynamic kink waves in the solar atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Van Doorsselaere, T. [Centre for Mathematical Plasma Astrophysics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, bus 2400, B-3001 Herverlee (Belgium); Soler, R.; Terradas, J. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Verth, G., E-mail: marcel.goossens@wis.kuleuven.be [Solar Physics and Space Plasma Research Centre (SP2RC), The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2014-06-10

    Magnetohydrodynamic (MHD) kink waves have now been observed to be ubiquitous throughout the solar atmosphere. With modern instruments, they have now been detected in the chromosphere, interface region, and corona. The key purpose of this paper is to show that kink waves do not only involve purely transverse motions of solar magnetic flux tubes, but the velocity field is a spatially and temporally varying sum of both transverse and rotational motion. Taking this fact into account is particularly important for the accurate interpretation of varying Doppler velocity profiles across oscillating structures such as spicules. It has now been shown that, as well as bulk transverse motions, spicules have omnipresent rotational motions. Here we emphasize that caution should be used before interpreting the particular MHD wave mode/s responsible for these rotational motions. The rotational motions are not necessarily signatures of the classic axisymmetric torsional Alfvén wave alone, because kink motion itself can also contribute substantially to varying Doppler velocity profiles observed across these structures. In this paper, the displacement field of the kink wave is demonstrated to be a sum of its transverse and rotational components, both for a flux tube with a discontinuous density profile at its boundary, and one with a more realistic density continuum between the internal and external plasma. Furthermore, the Doppler velocity profile of the kink wave is forward modeled to demonstrate that, depending on the line of sight, it can either be quite distinct or very similar to that expected from a torsional Alfvén wave.

  18. Transverse and longitudinal angular momenta of light

    Energy Technology Data Exchange (ETDEWEB)

    Bliokh, Konstantin Y., E-mail: k.bliokh@gmail.com [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Nonlinear Physics Centre, RSPhysE, The Australian National University, Canberra, ACT 0200 (Australia); Nori, Franco [Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198 (Japan); Physics Department, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2015-08-26

    We review basic physics and novel types of optical angular momentum. We start with a theoretical overview of momentum and angular momentum properties of generic optical fields, and discuss methods for their experimental measurements. In particular, we describe the well-known longitudinal (i.e., aligned with the mean momentum) spin and orbital angular momenta in polarized vortex beams. Then, we focus on the transverse (i.e., orthogonal to the mean momentum) spin and orbital angular momenta, which were recently actively discussed in theory and observed in experiments. First, the recently-discovered transverse spin  angular momenta appear in various structured fields: evanescent waves, interference fields, and focused beams. We show that there are several kinds of transverse spin angular momentum, which differ strongly in their origins and physical properties. We describe extraordinary features of the transverse optical spins and overview recent experiments. In particular, the helicity-independent transverse spin inherent in edge evanescent waves offers robust spin–direction coupling at optical interfaces (the quantum spin Hall effect of light). Second, we overview the transverse orbital angular momenta of light, which can be both extrinsic and intrinsic. These two types of the transverse orbital angular momentum are produced by spatial shifts of the optical beams (e.g., in the spin Hall effect of light) and their Lorentz boosts, respectively. Our review is underpinned by a unified theory of the angular momentum of light based on the canonical momentum and spin densities, which avoids complications associated with the separation of spin and orbital angular momenta in the Poynting picture. It allows us to construct a comprehensive classification of all known optical angular momenta based on their key parameters and main physical properties.

  19. Modelling the transverse distribution of velocity and suspended sediment in tidal estuaries

    NARCIS (Netherlands)

    Huijts, K.M.H.

    2011-01-01

    An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with fresh water derived from land drainage. Examples are the Western Scheldt River Estuary and the Chesapeake Bay. Within these environments complex

  20. Pressure-induced emergence of unusually high-frequency transverse excitations in a liquid alkali metal: Evidence of two types of collective excitations contributing to the transverse dynamics at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Bryk, Taras [Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Street, UA-79011 Lviv (Ukraine); Lviv Polytechnic National University, 12 S. Bandera Street, UA-79013 Lviv (Ukraine); Ruocco, G. [Dipartimento di Fisica, Universita di Roma La Sapienza, 5 Piazzale Aldo Moro, I-00185 Roma (Italy); Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia, 295 Viale Regina Elena, I-00161 Roma (Italy); Scopigno, T. [Dipartimento di Fisica, Universita di Roma La Sapienza, 5 Piazzale Aldo Moro, I-00185 Roma (Italy); IPCF-CNR, c/o Universita di Roma La Sapienza, 5 Piazzale Aldo Moro, I-00185 Roma (Italy); Seitsonen, Ari P. [Département de Chimie, Université de Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Département de Chimie, École Normale Supérieure, 24 rue Lhomond, F-75005 Paris (France)

    2015-09-14

    Unlike phonons in crystals, the collective excitations in liquids cannot be treated as propagation of harmonic displacements of atoms around stable local energy minima. The viscoelasticity of liquids, reflected in transition from the adiabatic to elastic high-frequency speed of sound and in absence of the long-wavelength transverse excitations, results in dispersions of longitudinal (L) and transverse (T) collective excitations essentially different from the typical phonon ones. Practically, nothing is known about the effect of high pressure on the dispersion of collective excitations in liquids, which causes strong changes in liquid structure. Here dispersions of L and T collective excitations in liquid Li in the range of pressures up to 186 GPa were studied by ab initio simulations. Two methodologies for dispersion calculations were used: direct estimation from the peak positions of the L/T current spectral functions and simulation-based calculations of wavenumber-dependent collective eigenmodes. It is found that at ambient pressure, the longitudinal and transverse dynamics are well separated, while at high pressures, the transverse current spectral functions, density of vibrational states, and dispersions of collective excitations yield evidence of two types of propagating modes that contribute strongly to transverse dynamics. Emergence of the unusually high-frequency transverse modes gives evidence of the breakdown of a regular viscoelastic theory of transverse dynamics, which is based on coupling of a single transverse propagating mode with shear relaxation. The explanation of the observed high-frequency shift above the viscoelastic value is given by the presence of another branch of collective excitations. With the pressure increasing, coupling between the two types of collective excitations is rationalized within a proposed extended viscoelastic model of transverse dynamics.

  1. Wave propagation and group velocity

    CERN Document Server

    Brillouin, Léon

    1960-01-01

    Wave Propagation and Group Velocity contains papers on group velocity which were published during the First World War and are missing in many libraries. It introduces three different definitions of velocities: the group velocity of Lord Rayleigh, the signal velocity of Sommerfeld, and the velocity of energy transfer, which yields the rate of energy flow through a continuous wave and is strongly related to the characteristic impedance. These three velocities are identical for nonabsorbing media, but they differ considerably in an absorption band. Some examples are discussed in the last chapter

  2. Salud ambiental: conceptos y actividades

    OpenAIRE

    Gonzalo A. Ordóñez

    2000-01-01

    La finalidad del trabajo es aportar información y propuestas conceptuales que faciliten la tarea de quienes tienen a su cargo la sistematización institucional de la salud ambiental. Se hace un análisis de la noción de "ambiente" para la cual se sugiere una definición, y se examina el lugar de la salud ambiental en el contexto de los problemas ambientales y sus vertientes "verde" y "azul". Se examinan denominaciones equivalentes de salud ambiental y se introducen los servicios de salud ambient...

  3. Displacement of an electric arc by a stationary transverse magnetic field to different pressures of the ionized gas

    International Nuclear Information System (INIS)

    Ramos, J.

    1987-01-01

    The displacement of a wall-stabilized electric arc by a stationary transverse magnetic field is measured to different pressures of the ionized gas. The increase of the pressure makes the heat transfer function and the mass flow velocity in the arc column to raise, and it makes the arc displacement to decrease. (author)

  4. The Utility of the Extended Images in Ambient Seismic Wavefield Migration

    Science.gov (United States)

    Girard, A. J.; Shragge, J. C.

    2015-12-01

    Active-source 3D seismic migration and migration velocity analysis (MVA) are robust and highly used methods for imaging Earth structure. One class of migration methods uses extended images constructed by incorporating spatial and/or temporal wavefield correlation lags to the imaging conditions. These extended images allow users to directly assess whether images focus better with different parameters, which leads to MVA techniques that are based on the tenets of adjoint-state theory. Under certain conditions (e.g., geographical, cultural or financial), however, active-source methods can prove impractical. Utilizing ambient seismic energy that naturally propagates through the Earth is an alternate method currently used in the scientific community. Thus, an open question is whether extended images are similarly useful for ambient seismic migration processing and verifying subsurface velocity models, and whether one can similarly apply adjoint-state methods to perform ambient migration velocity analysis (AMVA). Herein, we conduct a number of numerical experiments that construct extended images from ambient seismic recordings. We demonstrate that, similar to active-source methods, there is a sensitivity to velocity in ambient seismic recordings in the migrated extended image domain. In synthetic ambient imaging tests with varying degrees of error introduced to the velocity model, the extended images are sensitive to velocity model errors. To determine the extent of this sensitivity, we utilize acoustic wave-equation propagation and cross-correlation-based migration methods to image weak body-wave signals present in the recordings. Importantly, we have also observed scenarios where non-zero correlation lags show signal while zero-lags show none. This may be a valuable missing piece for ambient migration techniques that have yielded largely inconclusive results, and might be an important piece of information for performing AMVA from ambient seismic recordings.

  5. Modeling the Formation of Transverse Weld during Billet-on-Billet Extrusion

    Directory of Open Access Journals (Sweden)

    Yahya Mahmoodkhani

    2014-04-01

    Full Text Available A comprehensive mathematical model of the hot extrusion process for aluminum alloys has been developed and validated. The plasticity module was developed using a commercial finite element package, DEFORM-2D, a transient Lagrangian model which couples the thermal and deformation phenomena. Validation of the model against industrial data indicated that it gave excellent predictions of the pressure during extrusion. The finite element predictions of the velocity fields were post-processed to calculate the thickness of the surface cladding as one billet is fed in after another through the die (i.e., the transverse weld. The mathematical model was then used to assess the effect a change in feeder dimensions would have on the shape, thickness and extent of the transverse weld during extrusion. Experimental measurements for different combinations of billet materials show that the model is able to accurately predict the transverse weld shape as well as the clad surface layer to thicknesses of 50 µm. The transverse weld is significantly affected by the feeder geometry shape, but the effects of ram speed, billet material and temperature on the transverse weld dimensions are negligible.

  6. Comparison of extended hemicolectomy versus transverse colectomy in patients with cancer of the transverse colon.

    Science.gov (United States)

    van Rongen, I; Damhuis, R A M; van der Hoeven, J A B; Plaisier, P W

    2013-01-01

    Cancer of the transverse colon is rare and postoperative mortality tends to be high. Standard surgical treatment involves either extended hemicolectomy or transverse colectomy, depending on the location of the tumour. The aim of the present study was to compare postoperative mortality and five-year survival between these types of surgery. For this observational study, data on patients with a tumour of the transverse colon, treated by open resection in the Dordrecht Hospital from 1989 through 2003, were derived from the database of the regional cancer registry. Information on type of resection, tumour stage, complications, postoperative mortality (30-day) and survival was abstracted from the medical files. Patients with multi-organ surgery, (sub)total colectomy or stage IV disease were excluded from the analysis, leaving a total series of 103 patients. Transverse colectomy comprised one third of operations, predominantly involving partial resections. Postoperative mortality was 6% (2/34) after transverse colectomy and 7% (5/69) after extended hemicolectomy. Five-year survival was slightly higher for the hemicolectomy group (61% versus 50%), but this difference did not reach statistical significance (p = 0.34). Our results confirm the high postoperative risk after surgery for cancer of the transverse colon and show that this risk does not depend on the type of surgery. Considering the satisfactory results after partial transverse colectomy, segmental resections may be considered as an option for the treatment of localised tumours of the transverse colon.

  7. Three-dimensional particle-in-cell simulations of a plasma jet/cloud streaming across a transverse magnetic field

    Science.gov (United States)

    Voitcu, Gabriel; Echim, Marius

    2014-05-01

    The dynamics of collisionless plasma jets/clouds in magnetic field configurations typical for the terrestrial magnetotail and frontside magnetosheath is a topic of interest for understanding the physics of the magnetosphere and its interaction with the solar wind. The presence of high-speed jets in the frontside magnetosheath has been recently proved experimentally by Cluster and THEMIS spacecrafts. There is increasing evidence that the bursty bulk flows in the magnetotail have jet-like features. In the present paper we use fully electromagnetic 3D explicit particle-in-cell (PIC) simulations to investigate the interaction of a localized three-dimensional plasma element/jet/cloud with a transverse magnetic field. We consider a plasma jet/cloud that moves in vacuum and perpendicular to an ambient magnetic field. Ampère and Faraday's laws are used to compute the self-consistent electric and magnetic fields on a three-dimensional spatial grid having a step-size of the order of the Debye length and using a time-step that resolves the plasma frequency. The initial magnetic field inside the simulation domain is uniform and the plasma bulk velocity at the beginning of the simulation is normal to the magnetic field direction. The total time scale of the simulation is of the order of few ion Larmor periods. Space and time variations of the plasma parameters and of the electromagnetic field are analyzed and discussed. We emphasize non-MHD effects like the energy-dispersion signatures at the edges of the plasma element, similar to results previously reported by Voitcu and Echim (2012) using test-kinetic simulations. Acknowledgments: Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

  8. Possibilities for reduction of transverse projected emittances by partial removal of transverse to longitudinal beam correlations

    International Nuclear Information System (INIS)

    Balandin, V.; Decking, W.; Golubeva, N.

    2014-09-01

    We show that if in the particle beam there are linear correlations between energy of particles and their transverse positions and momenta (linear beam dispersions), then the transverse projected emittances always can be reduced by letting the beam to pass through magnetostatic system with specially chosen nonzero lattice dispersions. The maximum possible reduction of the transverse projected emittances occurs when all beam dispersions are zeroed, and the values of the lattice dispersions required for that are completely defined by the values of the beam dispersions and the beam rms energy spread and are independent from any other second-order central beam moments. Besides that, we prove that, alternatively, one can also use the lattice dispersions to remove linear correlations between longitudinal positions of particles and their transverse coordinates (linear beam tilts), but in this situation solution for the lattice dispersions is nonunique and the reduction of the transverse projected emittances is not guaranteed.

  9. Transverse Strains in Muscle Fascicles during Voluntary Contraction: A 2D Frequency Decomposition of B-Mode Ultrasound Images

    Directory of Open Access Journals (Sweden)

    James M. Wakeling

    2014-01-01

    Full Text Available When skeletal muscle fibres shorten, they must increase in their transverse dimensions in order to maintain a constant volume. In pennate muscle, this transverse expansion results in the fibres rotating to greater pennation angle, with a consequent reduction in their contractile velocity in a process known as gearing. Understanding the nature and extent of this transverse expansion is necessary to understand the mechanisms driving the changes in internal geometry of whole muscles during contraction. Current methodologies allow the fascicle lengths, orientations, and curvatures to be quantified, but not the transverse expansion. The purpose of this study was to develop and validate techniques for quantifying transverse strain in skeletal muscle fascicles during contraction from B-mode ultrasound images. Images were acquired from the medial and lateral gastrocnemii during cyclic contractions, enhanced using multiscale vessel enhancement filtering and the spatial frequencies resolved using 2D discrete Fourier transforms. The frequency information was resolved into the fascicle orientations that were validated against manually digitized values. The transverse fascicle strains were calculated from their wavelengths within the images. These methods showed that the transverse strain increases while the longitudinal fascicle length decreases; however, the extent of these strains was smaller than expected.

  10. Spin versus helicity in processes involving transversity

    CERN Document Server

    Mekhfi, Mustapha

    2011-01-01

    We construct the spin formalism in order to deal in a direct and natural way with processes involving transversity which are now of increasing popularity. The helicity formalism which is more appropriate for collision processes of definite helicity has been so far used also to manage processes with transversity, but at the price of computing numerous helicity amplitudes generally involving unnecessary kinematical variables.In a second step we work out the correspondence between both formalisms and retrieve in another way all results of the helicity formalism but in simpler forms.We then compute certain processes for comparison.A special process:the quark dipole magnetic moment is shown to be exclusively treated within the spin formalism as it is directly related to the transverse spin of the quark inside the baryon.

  11. Transversely Compressed- and Restrained Shear Joints

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Hansen, Christian Skodborg

    2013-01-01

    Anchorage of FRP strengthening systems where the deformation perpendicular to the FRP material is restrained or a compressive force is applied on the strengthening, seems to provide ductility, increased utilization of the FRP and failure modes which can be controlled through the anchorage method....... This paper presents theoretical model which can predict the response of transversely compressed and restrained single- and double lap shear joints. The interface material model is based on a cohesive law in the shear-slip plane with a descending branch and a uniform frictional stress added due...... to the friction in the crack, emanating from the transverse pressure or restraint. The theoretical model is compared with experimental results from transversely compressed single- and double shear joints. Also theoretical predictions of a mechanical integrated sleeve-wedge anchorage load capacity are carried out...

  12. Associated transverse energy in hadronic jet production

    International Nuclear Information System (INIS)

    Marchesini, G.; Webber, B.R.

    1988-01-01

    We present a theoretical study of the ''pedestal height'' in hadronic jet production, i.e., the mean transverse energy per unit of rapidity accompanying a high-transverse-energy jet. We find that perturbative QCD, supplemented by a Monte Carlo estimate of higher-order corrections and a soft underlying event structure similar to that of minimum-bias collisions, can account for the observed pedestal height and its dependence on jet transverse energy. We propose a way of separating the hard pedestal contribution from that of the underlying event by measuring the quantity , which is one-half the absolute difference of the pedestal heights on the two sides of the jet. This quantity is dominated by the hard QCD component, whereas = - is dominated by the soft underlying event. We also discuss the differential distribution of pedestal height and the charged multiplicity in the pedestal

  13. Ambient noise tomography of Eyjafjallajökull volcano, Iceland

    Science.gov (United States)

    Benediktsdóttir, Ásdís; Gudmundsson, Ólafur; Brandsdóttir, Bryndís; Tryggvason, Ari

    2017-11-01

    We present a shear-velocity model for the Eyjafjallajökull stratovolcano, based on ambient seismic noise tomography applied to seven months of data from six permanent stations and 10 temporary seismic stations, deployed during and after the 2010 volcanic unrest. Vertical components of noise were cross correlated resulting in 30 robust phase-velocity dispersion curves between 1.6 and 6.5 s in period, displaying a ± 20% variation in phase velocity beneath the volcano. The uneven distribution of noise sources, evaluated using signal-to-noise ratios, was estimated to cause less than 2% error in most curves. Sensitivity kernels showed resolution down to 10 km and the lateral resolution of the resulting phase-velocity maps was about 5 km. The model reveals east-west oriented high-velocity anomalies due east and west of the caldera. Between these a zone of lower velocity is identified, coinciding with the location of earthquakes that occurred during the summit eruption in April 2010. A shallow, southwest elongated low-velocity anomaly is located 5 km southwest of the caldera. The limited depth resolution of the shear-velocity model precludes detection of melt within the volcano.

  14. Development of a low cost method to estimate the seismic signature of a geothermal field form ambient noise analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Tibuleac, Ileana [Univ. of Nevada, Reno, NV (United States)

    2016-06-30

    A new, cost effective and non-invasive exploration method using ambient seismic noise has been tested at Soda Lake, NV, with promising results. The material included in this report demonstrates that, with the advantage of initial S-velocity models estimated from ambient noise surface waves, the seismic reflection survey, although with lower resolution, reproduces the results of the active survey when the ambient seismic noise is not contaminated by strong cultural noise. Ambient noise resolution is less at depth (below 1000m) compared to the active survey. In general, the results are promising and useful information can be recovered from ambient seismic noise, including dipping features and fault locations.

  15. Ambient og intelligent teknologi

    DEFF Research Database (Denmark)

    Andersen, Peter Bøgh

     Dette notat handler om hvordan humanistisk og samfundsfaglig forskning i øjeblikket nyttiggøres ved udformning af IKT-anvendelser, der er indlejret i vor dagligdag i den forstand, at de indgår som et element i de aktiviteter, vi foretager på arbejdet eller i fritiden. Sådanne anvendelser kaldes ...... undertiden ambiente – noget der omslutter os på alle sider. Rapporten peger også på virkemidler som kan forbedre og øge en humanistisk og samfundsfaglig forskningsindsats....

  16. El periodismo ambiental

    OpenAIRE

    Grinberg, Miguel

    2008-01-01

    La problemática ambiental no posee una presencia estructurada en los medios de comunicación social de la Argentina. No encabeza secciones permanentes en los diarios de circulación nacional, donde es considerada parte de la información general. Y aparece como sección estable en muy pocos diarios provinciales. Surge episódicamente en la TV abierta o por cable, y en la radio, cuando hay catástrofes naturales (sequías o inundaciones), accidentes industriales y conflictos políticos o sectoriales r...

  17. Operative Method for Transverse Colon Carcinoma: Transverse Colectomy Versus Extended Colectomy.

    Science.gov (United States)

    Chong, Choon Seng; Huh, Jung Wook; Oh, Bo Young; Park, Yoon Ah; Cho, Yong Beom; Yun, Seong Hyeon; Kim, Hee Cheol; Lee, Woo Yong

    2016-07-01

    The type of surgery performed for primary transverse colon cancer varies based on tumor characteristics and surgeon perspective. The optimal oncological outcome following different surgical options has not been clearly established, and transverse colectomy has shown oncological equivalence only in small cohort studies. Our aim was to compare long-term oncological outcomes after transverse colectomy versus extended resection for transverse colon cancer. This study is a retrospective review of prospectively collected data. This study was conducted at a tertiary care hospital. All patients treated for transverse colon cancer at the Samsung Medical Center between 1995 and 2013 were included. Oncological outcomes were compared between 2 groups of patients: a transverse colectomy group and an extended colectomy group (which included extended right hemicolectomy and left hemicolectomy). A total of 1066 patients were included, of whom 750 (70.4%) underwent extended right hemicolectomy, 127 (11.9%) underwent transverse colectomy, and 189 (17.7%) underwent left hemicolectomy. According to univariate analysis, surgical approach, histological type, tumor morphology, cancer T and N stage, cancer size, and lymphovascular invasion were significant factors contributing to disease-free survival (DFS). However, as seen in multivariate analysis, only node-positive disease (HR = 2.035 (1.188-3.484)), tumors with ulcerative morphology (HR = 3.643 (1.132-11.725)), and the presence of vascular invasion (HR = 2.569 (1.455-4.538)) were significant factors for DFS. Further analysis with a propensity-matched cohort between the transverse and extended colectomy groups demonstrated no significant differences in DFS and overall survival. This study was limited because it was performed at a single institution and it was retrospective in nature. In terms of perioperative and oncological outcomes, transverse colectomy and extended colectomy did not differ despite a shorter specimen length and

  18. Inclusive eta production at large transverse momenta

    International Nuclear Information System (INIS)

    Donaldson, G.J.; Gordon, H.A.; Lai, K.; Stumer, I.; Barnes, A.V.; Mellema, D.J.; Tollestrup, A.V.; Walker, R.L.; Dahl, O.; Johnson, R.; Ogawa, A.; Pripstein, M.; Shannon, S.

    1978-01-01

    We have measured the ratio of inclusive production of eta to π 0 at transverse momenta above 1.5 GeV/c. Results are presented for various meson and proton beams with momenta of 100, 200, and 300 GeV/c incident upon a hydrogen target. The eta/π 0 production ratio is found to be independent of incident beam momentum and of the transverse and longitudinal momenta of production. The ratio for pion- and proton-induced reactions is 0.44 +- 0.05; for kaons, it is 0.74 +- 0.12

  19. Transverse posterior element fractures associated with torsion

    International Nuclear Information System (INIS)

    Abel, M.S.

    1989-01-01

    Six examples of a previously undescribed class of transverse vertebral element fractures are presented. These fractures differ from Chance and Smith fractures and their variants in the following respects: (1) the etiology is torsion and not flexion; (2) there is neither distraction of posterior ring fragments nor posterior ligament tears; (3) in contrast to Chance and Smith fractures, extension of the fracture into the vertebral body is absent or minimal; (4) the transverse process of the lumbar vertebra is avulsed at its base with a vertical fracture, not split horizontally. These fractures occur in cervical, lumbar, and sacral vertebrae in normal or compromised areas of the spine. (orig.)

  20. Results on large transverse momentum phenomena

    CERN Document Server

    Büsser, F W; Blumenfeld, B; Camilleri, L L; Cool, R L; Di Lella, L; Gladding, G; Lederman, Leon Max; Litt, L; Placci, A; Pope, B G; Segler, S L; Smith, A M; Yoh, J K; Zavattini, E

    1973-01-01

    Preliminary results of an experiment on large transverse momentum phenomena performed at the CERN-ISR at centre-of-mass energies of 52.7 and 44.8 GeV are presented. The topics studied were the inclusive reaction p+p to pi /sup 0/+'anything', where the pi /sup 0/ was emitted around 90 degrees in the centre- of-mass system, ( pi /sup 0/ pi /sup 0/) correlations, and the charged multiplicity associated with large transverse momentum pi /sup 0/'s. In addition, results of a search for electrons and electron pairs are included. (4 refs).

  1. [The transversality and health promotion schools].

    Science.gov (United States)

    Gavidia Catalán, V

    2001-01-01

    The following article shows the evolution of the schools contribution to the Health Education of children and young people. Moving on from the traditional concept of health, today, Health Education has a general and global meaning, which encompasses all of the physical, psychological and social aspects of health. These aspects define the characteristics of the "Healthy School". The need to broach the "transversal subject" offers schools the possibility of developing "transversality" in the Health Education. Finally, the concept of promoting health defines, together with the other subjects, that which we understand by "the heath promotion schools", which attempts to progress the full integration of schools in the society in which they are located.

  2. Dioxinas y medio ambiente

    Directory of Open Access Journals (Sweden)

    María Teresa Frejo Moya

    2011-12-01

    Full Text Available Con el término genérico dioxinas se designa al grupo de las dibenzo-p-dioxinas policloradas (PCDD y de los dibenzofuranos policlorados (PCDF, representantes típicos de los compuestos orgánicos persistentes (COPs. Se obtienen como productos secundarios no deseados de diversos procesos industriales en los que se emplea cloro en alguna de sus etapas. Las dioxinas han centrado en la última década una parte importante de la investigación médica en salud ambiental debido a su notable toxicidad, ya que son las sustancias químicas peligrosas más potentes creadas por el hombre, afectando al sistema nervioso e inmunitario, estando implicadas en la aparición de distintos tipos de cáncer y provocando la aparición de alteraciones hormonales, clasificándose actualmente como disruptores endocrinos. Por otra parte, su persistencia en el medio ambiente, resistencia a la degradación, bioacumulación y capacidad de transporte atmosférico entre las diversas fases medioambientales hace que sean considerados actualmente como compuestos peligrosos para el ser humano.

  3. Crisis ambiental y cristianismo

    Directory of Open Access Journals (Sweden)

    Felipe Cárdenas

    2008-01-01

    Full Text Available En el artículo se identifican y reconocen algunas opciones que se pueden desarrollar en el cristianismo en relación con la problemática ambiental. Se aborda el dilema bíblico suscitado por interpretaciones antiecológicas y ecológicas. Con base en una lectura de la Biblia, de testimonios cristianos, y en una rememoria de estructuras institucionales, como la parroquia, se analiza el valor que tiene el mensaje cristiano en lo referido a la mitigación de la crisis ambiental.This article identifies and recognizes some options that can be developed in Christianity in relation to the environmental problem. It starts by analyzing the biblical dilemma provoked by both ecological and antiecological interpretations. Based on a reading of the Bible, testimonies from Christians and with a rememory of institutional structures, like the parish, the valué of the Christian message for mitigating the environmental crisis is analyzed.

  4. Types for BioAmbients

    Directory of Open Access Journals (Sweden)

    Sara Capecchi

    2010-02-01

    Full Text Available The BioAmbients calculus is a process algebra suitable for representing compartmentalization, molecular localization and movements between compartments. In this paper we enrich this calculus with a static type system classifying each ambient with group types specifying the kind of compartments in which the ambient can stay. The type system ensures that, in a well-typed process, ambients cannot be nested in a way that violates the type hierarchy. Exploiting the information given by the group types, we also extend the operational semantics of BioAmbients with rules signalling errors that may derive from undesired ambients' moves (i.e. merging incompatible tissues. Thus, the signal of errors can help the modeller to detect and locate unwanted situations that may arise in a biological system, and give practical hints on how to avoid the undesired behaviour.

  5. Optimal Surgery for Mid-Transverse Colon Cancer: Laparoscopic Extended Right Hemicolectomy Versus Laparoscopic Transverse Colectomy.

    Science.gov (United States)

    Matsuda, Takeru; Sumi, Yasuo; Yamashita, Kimihiro; Hasegawa, Hiroshi; Yamamoto, Masashi; Matsuda, Yoshiko; Kanaji, Shingo; Oshikiri, Taro; Nakamura, Tetsu; Suzuki, Satoshi; Kakeji, Yoshihiro

    2018-04-02

    Although the feasibility and safety of laparoscopic surgery for transverse colon cancer have been shown by the recent studies, the optimal laparoscopic approach for mid-transverse colon cancer is controversial. We retrospectively analyzed the data of patients with the mid-transverse colon cancer at our institutions between January 2007 and April 2017. Thirty-eight and 34 patients who received extended right hemicolectomy and transverse colectomy, respectively, were enrolled. There were no significant differences in operating time, blood loss, and hospital stay between the two groups. Postoperative complications developed in 10 of 34 patients (29.4%; wound infection: 2 cases, anastomotic leakage: 2 cases, bowel obstruction: 1 case, incisional hernia: 2 cases, others: 3 cases) for the transverse colectomy group and in 4 of 38 patients (10.5%; wound infection: 1 case, anastomotic leakage: 0 case, bowel obstruction: 2 cases, incisional hernia: 0 case, others: 1 case) for the extended right hemicolectomy group (P = 0.014). Although the median number of harvested #221 and #222 LNs was similar between the two groups (6 vs. 8, P = 0.710, and 3 vs. 2, P = 0.256, respectively), that of #223 was significantly larger in extended right hemicolectomy than in transverse colectomy (3 vs. 1, P = 0.038). The 5-year disease-free and overall survival rates were 92.4 and 90.3% for the extended right hemicolectomy group, and 95.7 and 79.6% for the transverse colectomy group (P = 0.593 and P = 0.638, respectively). Laparoscopic extended right hemicolectomy and laparoscopic transverse colectomy offer similar oncological outcomes for mid-transverse colon cancer. Laparoscopic extended right hemicolectomy might be associated with fewer postoperative complications.

  6. Ambient Volatility of Triethyl Phosphate

    Science.gov (United States)

    2017-08-01

    AMBIENT VOLATILITY OF TRIETHYL PHOSPHATE ECBC-TR-1476 James H. Buchanan John J. Mahle RESEARCH AND...2017 2. REPORT TYPE Final 3. DATES COVERED (From - To) Oct 2016 – Jan 2017 4. TITLE: Ambient Volatility of Triethyl Phosphate 5a. CONTRACT...humidity on TEPO volatility is nearly as predicted by Raoult’s law, that is, vapor pressure suppression is proportional to ambient relative humidity. An

  7. Parametric Transverse Patterns in Broad Aperture Lasers

    DEFF Research Database (Denmark)

    Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik

    1998-01-01

    Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence...... on the geometrical size of the system is demonstrated even in the case of large-scale systems....

  8. Longitudinal Evaluation of Foetal Transverse Lie using ...

    African Journals Online (AJOL)

    Erah

    , lower segment fibroids in 2.7%, and ectopic kidney in 0.7%. In conclusion, transverse lie detected early in pregnancy is transient, and majority would convert to a longitudinal lie at term. Potential predisposing factors highlighted above ...

  9. Rapid communication: Transverse spin with coupled plasmons

    Indian Academy of Sciences (India)

    In contrast to some of the earlier studies, calculations are performed retaining the full lossy character of the metal. In the limit of vanishing losses, we present analytical results for the extraordinary spin for both the coupled modes. The results can have direct implications for enhancing the elusive transverse spin exploiting the ...

  10. Transverse momentum distributions of identified particles produced ...

    Indian Academy of Sciences (India)

    ... sources which can be regarded as partons or quarks in the interacting system. The particle is contributed by each source with gluons which have transverse momentum distributions in an exponential form. The modelling results are compared and found to be in agreement with the experimental data at high energies.

  11. Sex Education as a Transversal Subject

    Science.gov (United States)

    Rabelo, Amanda Oliveira; Pereira, Graziela Raupp; Reis, Maria Amélia; Ferreira, António G.

    2015-01-01

    Currently, sex education is in many countries a transversal subject, in which the school becomes a privileged place for the implementation of policies that aim at promoting "public health." Its design as a cross-cutting subject envisages fostering the dissemination of these subjects in all pedagogical and curricular fields; however, we…

  12. Transverse spin and momentum correlations in quantum ...

    Indian Academy of Sciences (India)

    (SSAs) in hard scattering processes when transverse momentum scales are on the order of quarks in hadrons, ... are of particular interest as they emerge from the colour gauge invariant definition of the quark-gluon-quark ..... For n ≥ 3, there are enough powers of l+ to eliminate this divergence. f(p2) is a covariant Gaussian ...

  13. TRANSVERSE COLON POUCH: AN ALTERNATIVE TO ...

    African Journals Online (AJOL)

    Objective Urinary diversion after pelvic irradiation is challenging. The use of irradiated bowel is mostly complicated and unsuccessful. Therefore, the use of an exclusively non-irradiated bowel segment, such as the transverse colon, is a good alternative in such situation. Patients and Methods Twenty-nine female patients ...

  14. Transversals in non-discrete groups

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 115; Issue 4 ... Given any right quasigroup with a Tychonoff topology , it is proved that there exists a Hausdorff topological group in which can be embedded algebraically and topologically as a right transversal of a subgroup (not necessarily closeed).

  15. Rapid communication: Transverse spin with coupled plasmons

    Indian Academy of Sciences (India)

    Samyobrata Mukherjee

    2017-07-25

    Jul 25, 2017 ... spline interpolation from the data of Johnson and Christy. [31]. But first, we have to deal with normalization in order to make our comparisons of the transverse spin for different wavelengths and metal film thicknesses d meaningful. We normalize the power flow into the sys- tem at x = 0 to unity. ∫ ∞. −∞.

  16. Transverse Ising model with multi-impurity

    International Nuclear Information System (INIS)

    Huang, Xuchu; Yang, Zhihua

    2015-01-01

    We study the transverse Ising spin model with spin-1 impurities under the exact solution. We develop a universal method to deal with the multi-impurity problem by introducing a displacement quantity in the wave function and get a recursive formula to simplify the calculation of the partition function. This allows us to rigorously determine the impurity effects for a specific distribution of impurity in the thermodynamic limit. The low temperature behaviors are governed by the interplay between host and impurity excitations, and the quantum critical fluctuations around the critical point of the transverse Ising model are tuned by the transverse field and the concentration of impurity. However the impurity effects are limited, which depends on the host–impurity exchange interaction and the coupling strength of impurities. - Highlights: • A universal method is proposed to exactly resolve the transverse Ising model with many impurities. • The phase diagram of the ground state is obtained for different impurity concentrations. • The thermodynamic properties can be determined rigorously by a recursive formula in the thermodynamic limit

  17. Transversals in non-discrete groups

    Indian Academy of Sciences (India)

    1963). [7] Lal R, Transversals in groups, J. Alg. 181 (1996) 70–81. [8] Lal R and Shukla R P, Perfectly stable subgroups of finite groups, Comm. Alg. 24(2). (1996) 643–657. [9] Lal R and Shukla R P, A characterization of Tarski monsters, ...

  18. Rapid communication: Transverse spin with coupled plasmons

    Indian Academy of Sciences (India)

    Samyobrata Mukherjee

    2017-07-25

    Jul 25, 2017 ... Rapid communication: Transverse spin with coupled plasmons. SAMYOBRATA MUKHERJEE1, A V GOPAL2 and S DUTTA GUPTA1,∗. 1School of Physics, University of Hyderabad, Gachibowli, Hyderabad 500 046, India. 2Department of Condensed Matter Physics and Materials Science, Tata Institute of ...

  19. EFFECT OF CHANNEL BENDS ON TRANSVERSE MIXING

    African Journals Online (AJOL)

    user

    2017-06-05

    Jun 5, 2017 ... dy, where d is the flow depth, was found to vary laterally in all cross-sections. As the spiral motion due to the second bend develops it displaces the residual spiral motion from the first bend towards the outer bend causing it to decay completely around the middle of this bend. Transverse Tracer Distribution.

  20. Viewpoint-based ambient occlusion.

    Science.gov (United States)

    González, Francisco; Sbert, Mateu; Feixas, Miquel

    2008-01-01

    A new ambient occlusion technique builds a channel between various viewpoints and an object's polygons, providing the information needed to create an occlusion map with multiple application possibilities.

  1. 3D Vector Velocity Estimation using a 2D Phased Array

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2011-01-01

    A method to estimate the three dimensional (3D) velocity vector is presented is this paper. 3D velocity vector techniques are needed to measure the full velocity and characterize the complicated flow patterns in the human body. The Transverse Oscillation (TO) method introduces oscillations...... transverse to the ultrasound beam, which enables the estimation of the transverse velocity. To expand the method from 2D to 3D, it is proposed to decouple the velocity estimation into separate estimates of vx, vy, and vz in combination with a 2D phased matrix array. Through simulations the feasibility...... of using the TO method for estimation 3D velocity vectors, and the proposed decoupling is demonstrated. A 64x64 and a 32x32 elements transducer are emulated using Field II. Plug flow with a speed of 1 m/s in a small region is rotated in the XY -plane. A binary flow example with [vx,vy]=[1,0] and [0,1] m...

  2. 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...

  3. Ambient mass spectrometry imaging

    DEFF Research Database (Denmark)

    Janfelt, Christian; Nørgaard, Asger W

    2012-01-01

    Easy ambient sonic spray ionization (EASI) and desorption electrospray ionization (DESI) were used for imaging of a number of samples, including sections of rat brain and imprints of plant material on porous Teflon. A novel approach termed Displaced Dual-mode Imaging was utilized for the direct...... comparison of the two methods: Images were recorded with the individual rows alternating between EASI and DESI, yielding a separate image for each technique recorded under perfectly similar conditions on the same sample. EASI works reliably for imaging of all samples, but the choice of spray solvent and flow...... rate is more critical in tissue imaging with EASI than with DESI. The overall sensitivity of EASI is, in general, slightly lower than that of DESI, and the representation of the dynamic range is different in images of the two techniques for some samples. However, for abundant compounds, EASI works well...

  4. Stochastic analysis of pitch angle scattering of charged particles by transverse magnetic waves

    International Nuclear Information System (INIS)

    Lemons, Don S.; Liu Kaijun; Winske, Dan; Gary, S. Peter

    2009-01-01

    This paper describes a theory of the velocity space scattering of charged particles in a static magnetic field composed of a uniform background field and a sum of transverse, circularly polarized, magnetic waves. When that sum has many terms the autocorrelation time required for particle orbits to become effectively randomized is small compared with the time required for the particle velocity distribution to change significantly. In this regime the deterministic equations of motion can be transformed into stochastic differential equations of motion. The resulting stochastic velocity space scattering is described, in part, by a pitch angle diffusion rate that is a function of initial pitch angle and properties of the wave spectrum. Numerical solutions of the deterministic equations of motion agree with the theory at all pitch angles, for wave energy densities up to and above the energy density of the uniform field, and for different wave spectral shapes.

  5. Ambient Noise Tomography in Koyna-Warna region.

    Science.gov (United States)

    Rohilla, S.; Rao, N. P.; Gerstoft, P.; Yao, H.; Fang, H.; Davulluri, S.

    2017-12-01

    In the present study Ambient Noise tomography has been done in the Koyna-Warna region of western India to decipher the complex structural setting and its linkage to the seismogenesis in this unique Reservoir Triggered Seismicity zone. The 3-D velocity model obtained from the study clearly brings out the lateral and vertical variations of shear velocity in the region down to a depth of about 10 km. In the Koyna region, seismicity distribution along the NNE-SSW trending Donachiwada fault zone is seen coinciding with a low velocity zone between two competent zones with a very high velocity > 4.0 km/s. The seismicity between the Koyna and Warna regions roughly trending NW-SE can be clearly seen in the NE-SW depth sections coinciding with a low velocity zone interspersed between two high velocity zones. The most active seismicity cluster south of the Warna Lake correlates with a near-vertical velocity discontinuity with a contrast of about 0.5 km/s is seen in an EW depth section. The study has helped in delineating the major fault zones of the Koyna-Warna region and enabled understanding the seismogenesis with respect to the structural controls in a RTS enviroment.

  6. In Vivo Three-Dimensional Velocity Vector Imaging and Volumetric Flow Rate Measurements

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev

    2013-01-01

    The three-dimensional (3-D) Transverse Oscillation (TO) method is used to obtain 3-D velocity vector estimates in two orthogonal planes. The method is suitable for a real-time implementation. Data are acquired using a Vermon 3.0 MHz 32x32 element 2-D phased array and the experimental ultrasound s...

  7. Deviation velocity and second order adiabatic invariants by a new iterative technique of integration by parts

    International Nuclear Information System (INIS)

    Martin, P.; Sebastia, J.-M.

    1982-01-01

    The deviation velocities and the first adiabatic invariant of a charged particle moving in an electromagnetic field are obtained by a technique which uses the motion description in terms of a complex (transversal component) and a real (longitudinal component) variables referred to a rotational reference trihedral. (L.C.) [pt

  8. Mapping of moveout in tilted transversely isotropic media

    KAUST Repository

    Stovas, A.

    2013-09-09

    The computation of traveltimes in a transverse isotropic medium with a tilted symmetry axis tilted transversely isotropic is very important both for modelling and inversion. We develop a simple analytical procedure to map the traveltime function from a transverse isotropic medium with a vertical symmetry axis (vertical transversely isotropic) to a tilted transversely isotropic medium by applying point-by-point mapping of the traveltime function. This approach can be used for kinematic modelling and inversion in layered tilted transversely isotropic media. © 2013 European Association of Geoscientists & Engineers.

  9. In vivo comparison of three ultrasound vector velocity techniques to MR phase contrast angiography

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Oddershede, Niels

    2009-01-01

    The objective of this paper is to validate angle independent vector velocity methods for blood velocity estimation. Conventional Doppler ultrasound (US) only estimates the blood velocity along the US beam direction where the estimate is angle corrected assuming laminar flow parallel to vessel...... boundaries. This results in incorrect blood velocity estimates, when angle of insonation approaches 90° or when blood flow is non-laminar. Three angle independent vector velocity methods are evaluated in this paper: directional beamforming (DB), synthetic aperture flow imaging (STA) and transverse....... MRA = 0.24 ml (95% CI: −0.32–0.81) with LoA = −1.41–1.90 ml. According to the results, reliable volume flow estimates can be obtained with all three methods. The three US vector velocity techniques can yield quantitative insight into flow dynamics and visualize complex flow patterns, which potentially...

  10. Validating Firewalls in Mobile Ambients

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Hansen, René Rydhof

    1999-01-01

    The ambient calculus is a calculus of computation that allows active processes (mobile ambients) to move between sites. A firewall is said to be protective whenever it denies entry to attackers not possessing the required passwords. We devise a polynomial time algorithm for rejecting proposed...

  11. Validating Firewalls in Mobile Ambients

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Hansen, René Rydhof

    1999-01-01

    The ambient calculus is a calculus of computation that allows active processes (mobile ambients) to move between sites. A firewall is said to be protective whenever it denies entry to attackers not possessing the required passwords. We devise a polynomial time algorithm for rejecting proposed fir...... are semantically sound, and we demonstrate that each process admits a least analysis....

  12. Foro Ambiental : CEDENMA, Asamblea Constituyente

    Directory of Open Access Journals (Sweden)

    Anne-Lise Naizot

    2013-09-01

    Full Text Available Resumen de la Mesa redonda: Orientaciones de la nueva Constitución ecuatoriana en materia ambiental: ¿avances o retrocesos en relación con el marco político y filosófico ambiental vigente en algunos países de la región?

  13. Suppression of two-stream hose instabilities at wavelengths shorter than the beam’s transverse size

    Directory of Open Access Journals (Sweden)

    R. A. Bosch

    2003-07-01

    Full Text Available Transverse hose instability may disrupt the propagation of a charged-particle beam in a channel of oppositely charged particles. A theoretical model predicts stabilization of this two-stream instability when the instability wavelength becomes smaller than the beam’s transverse size in a frame of reference where the instability’s phase velocity is nonrelativistic. Suppression of short-wavelength instability is also predicted when a proton beam propagates through a channel consisting of electrons and positive ions, consistent with previous experimental results.

  14. Transmural transverse stiffness estimation in vascular shear wave imaging: A simulation and phantom study

    Science.gov (United States)

    Guo, Yuexin; Lo, Ho Yuen; Lee, Wei-Ning

    2017-05-01

    Shear wave imaging has emerged as a potential non-invasive technique for the quantitative assessment of the arterial shear modulus. Nonetheless, the arterial elasticity estimation in the transverse direction has been overlooked compared with the longitudinal direction, and the estimated transmural stiffness has rarely been evaluated. Accurate depiction of the transverse stiffness across the thin arterial wall warrants comprehensive characterization in both normal and pathological conditions. This study estimated the transmural arterial shear modulus in both the longitudinal ( μ Long) and transverse directions ( μ Trans) using group ( c T) and phase velocities ( c p h) in finite element models and hollow cylindrical tissue-mimicking phantoms with various shape factors. The results were validated against mechanical testing. Zero-order antisymmetric Lamb wave and circumferential Lamb type wave models were considered in the longitudinal and transverse directions of the thin-walled hollow cylinder, respectively. The results derived from the model with the thin plate assumption confirmed that c T underestimated μ Long and μ Trans. Unlike the c p h-based μ Long estimates that were in excellent agreement with measured values, the c p h-based μ Trans estimates were found to be comparable to c p h-based μ Long at the inner wall but increased radially outward. Transmural μ Trans estimation using c p h was demonstrated to be feasible for thin-walled hollow cylinders but necessitated careful account of the wall geometry, in particular the shape factor.

  15. A compact fiber optics-based heterodyne combined normal and transverse displacement interferometer.

    Science.gov (United States)

    Zuanetti, Bryan; Wang, Tianxue; Prakash, Vikas

    2017-03-01

    While Photonic Doppler Velocimetry (PDV) has become a common diagnostic tool for the measurement of normal component of particle motion in shock wave experiments, this technique has not yet been modified for the measurement of combined normal and transverse motion, as needed in oblique plate impact experiments. In this paper, we discuss the design and implementation of a compact fiber-optics-based heterodyne combined normal and transverse displacement interferometer. Like the standard PDV, this diagnostic tool is assembled using commercially available telecommunications hardware and uses a 1550 nm wavelength 2 W fiber-coupled laser, an optical focuser, and single mode fibers to transport light to and from the target. Two additional optical probes capture first-order beams diffracted from a reflective grating at the target free-surface and deliver the beams past circulators and a coupler where the signal is combined to form a beat frequency. The combined signal is then digitized and analyzed to determine the transverse component of the particle motion. The maximum normal velocity that can be measured by this system is limited by the equivalent transmission bandwidth (3.795 GHz) of the combined detector, amplifier, and digitizer and is estimated to be ∼2.9 km/s. Sample symmetric oblique plate-impact experiments are performed to demonstrate the capability of this diagnostic tool in the measurement of the combined normal and transverse displacement particle motion.

  16. An Automated Algorithm for Identifying and Tracking Transverse Waves in Solar Images

    Science.gov (United States)

    Weberg, Micah J.; Morton, Richard J.; McLaughlin, James A.

    2018-01-01

    Recent instrumentation has demonstrated that the solar atmosphere supports omnipresent transverse waves, which could play a key role in energizing the solar corona. Large-scale studies are required in order to build up an understanding of the general properties of these transverse waves. To help facilitate this, we present an automated algorithm for identifying and tracking features in solar images and extracting the wave properties of any observed transverse oscillations. We test and calibrate our algorithm using a set of synthetic data, which includes noise and rotational effects. The results indicate an accuracy of 1%–2% for displacement amplitudes and 4%–10% for wave periods and velocity amplitudes. We also apply the algorithm to data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and find good agreement with previous studies. Of note, we find that 35%–41% of the observed plumes exhibit multiple wave signatures, which indicates either the superposition of waves or multiple independent wave packets observed at different times within a single structure. The automated methods described in this paper represent a significant improvement on the speed and quality of direct measurements of transverse waves within the solar atmosphere. This algorithm unlocks a wide range of statistical studies that were previously impractical.

  17. Dynamic Behavior of Spicules Inferred from Perpendicular Velocity Components

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Rahul; Verth, Gary; Erdélyi, Robertus [Solar Physics and Space Plasma Research Centre, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2017-05-10

    Understanding the dynamic behavior of spicules, e.g., in terms of magnetohydrodynamic (MHD) wave mode(s), is key to unveiling their role in energy and mass transfer from the photosphere to corona. The transverse, torsional, and field-aligned motions of spicules have previously been observed in imaging spectroscopy and analyzed separately for embedded wave-mode identification. Similarities in the Doppler signatures of spicular structures for both kink and torsional Alfvén wave modes have led to the misinterpretation of the dominant wave mode in these structures and is a subject of debate. Here, we aim to combine line- of-sight (LOS) and plane-of-sky (POS) velocity components using the high spatial/temporal resolution H α imaging-spectroscopy data from the CRisp Imaging SpectroPolarimeter based at the Swedish Solar Telescope to achieve better insight into the underlying nature of these motions as a whole. The resultant three-dimensional velocity vectors and the other derived quantities (e.g., magnetic pressure perturbations) are used to identify the MHD wave mode(s) responsible for the observed spicule motion. We find a number of independent examples where the bulk transverse motion of the spicule is dominant either in the POS or along the LOS. It is shown that the counterstreaming action of the displaced external plasma due to spicular bulk transverse motion has a similar Doppler profile to that of the m = 0 torsional Alfvén wave when this motion is predominantly perpendicular to the LOS. Furthermore, the inferred magnetic pressure perturbations support the kink wave interpretation of observed spicular bulk transverse motion rather than any purely incompressible MHD wave mode, e.g., the m = 0 torsional Alfvén wave.

  18. High Transverse Energy Proton - Nuclear Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Rice, James Allen [Rice Univ., Houston, TX (United States)

    1983-06-01

    A study of high transverse energy events resulting from 400 GeV protons scattering from targets of hydrogen, carbon, aluminum, copper, tin, and lead has been performed with the E609 apparatus at Fermilab. Wire chambers and a highly segmented calorimeter detect secondary particles. The use of efficient jet collecting triggers and of a beam jet calorimeter have been originally applied to nuclear target studies in this thesis. $A^{\\alpha}$ scaling with hydrogen deviations is observed for $E_T$ and planarity. The data provide evidence that $A^{\\alpha}$ scaling results from multiple scattering.Evidence for hadron jets is seen with a large solid angle calorimeter for all the targets when triggers requiring two high $E_T$ single particles are employed. Jet cross-sections for nuclei are approximately determined herein. Jet event angular distributions possibly indicate that low and high transverse energy particles in jets from nuclei may result, in part, from different types of interactions.

  19. Transversals of Complex Polynomial Vector Fields

    DEFF Research Database (Denmark)

    Dias, Kealey

    Vector fields in the complex plane are defined by assigning the vector determined by the value P(z) to each point z in the complex plane, where P is a polynomial of one complex variable. We consider special families of so-called rotated vector fields that are determined by a polynomial multiplied...... by rotational constants. Transversals are a certain class of curves for such a family of vector fields that represent the bifurcation states for this family of vector fields. More specifically, transversals are curves that coincide with a homoclinic separatrix for some rotation of the vector field. Given...... a concrete polynomial, it seems to take quite a bit of work to prove that it is generic, i.e. structurally stable. This has been done for a special class of degree d polynomial vector fields having simple equilibrium points at the d roots of unity, d odd. In proving that such vector fields are generic...

  20. Borel resummation of transverse momentum distributions

    International Nuclear Information System (INIS)

    Bonvini, Marco; Forte, Stefano; Ridolfi, Giovanni

    2009-01-01

    We present a new prescription for the resummation of contributions due to soft gluon emission to the transverse momentum distribution of processes such as Drell-Yan production in hadronic collisions. We show that familiar difficulties in obtaining resummed results as a function of transverse momentum starting from impact-parameter space resummation are related to the divergence of the perturbative expansion of the momentum-space result. We construct a resummed expression by Borel resummation of this divergent series, removing the divergence in the Borel inversion through the inclusion of a suitable higher twist term. The ensuing resummation prescription is free of numerical instabilities, is stable upon the inclusion of subleading terms, and the original divergent perturbative series is asymptotic to it. We compare our results to those obtained using alternative prescriptions, and discuss the ambiguities related to the resummation procedure

  1. Transverse Instability of a Rectangular Bunch

    CERN Document Server

    Balbekov, Valeri

    2005-01-01

    Some results of theoretical investigations of transverse dipole instability of a rectangular bunch are reported in this paper. Such a form is characteristic of the bunch in a rectangular potential wall which is created by a barrier-shaped acceleration field. Similar regime is a major one for accumulating and cooling of antiproton beams in the Fermilab Recycler Ring. In this case, the known theory of transverse instability of a bunched beam is inapplicable directly both because of "unusual" form of phase trajectories and strong dependence of synchrotron frequency on energy. A series of equations, adequately describing the instability is derived in the paper. Exact analytical solution is obtained for space charge dominated impedance, and some approximate methods are proposed for arbitrary impedance. The theory is applied to the Fermilab Recycler Ring including a numerical simulation.

  2. MEASUREMENT OF TRANSVERSE ECHOES IN RHIC

    International Nuclear Information System (INIS)

    FISCHER, W.; SATOGATA, T.; TOMAS, R.

    2005-01-01

    Beam echoes are a very sensitive method to measure diffusion, and longitudinal echo measurements were performed in a number of machines. In RHIC, for the first time, a transverse beam echo was observed after applying a dipole kick followed by a quadrupole .kick. After application of the dipole kick, the dipole moment decohered completely due to lattice nonlinearities. When a quadrupole kick is applied at time τ after the dipole kick, the beam re-cohered at time 2τ thus showing an echo response. We describe the experimental setup and measurement results. In the measurements the dipole and quadrupole kick amplitudes, amplitude dependent tune shift, and the time between dipole and quadrupole kick were varied. In addition, measurements were taken with gold bunches of different intensities. These should exhibit different transverse diffusion rates due to intra-beam scattering

  3. Antiphospholipid antibody syndrome presenting as transverse myelitis

    Directory of Open Access Journals (Sweden)

    Javvid M Dandroo

    2015-01-01

    Full Text Available The antiphospholipid syndrome (APS is characterized by arterial and/or venous thrombosis and pregnancy morbidity in the presence of anticardiolipin antibodies and/or lupus anticoagulant. APS can occur either as a primary disorder or secondary to a connective tissue disease, most frequently systemic lupus erythematosus. Central nervous system involvement is one of the most prominent clinical manifestations of APS, and includes arterial and venous thrombotic events, psychiatric features, and a variety of other nonthrombotic neurological syndromes. Although the mechanism of neurological involvement in patients with APS is thought to be thrombotic in origin and endothelial dysfunction associated with antiphospholipid antibodies. APS presenting as acute transverse myelitis is very rarely seen with a prevalence rate of 1%. We are describing a foreigner female presenting as acute transverse myelitis which on evaluation proved to be APS induced. So far, very few cases have been reported in literature with APS as etiology.

  4. Nonlinear theory of transverse beam echoes

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Tanaji; Li, Yuan Shen

    2017-10-04

    Transverse beam echoes can be excited with a single dipole kick followed by a single quadrupole kick. They have been used to measure diffusion in hadron beams and have other diagnostic capabilities. Here we develop theories of the transverse echo nonlinear in both the dipole and quadrupole kick strengths. The theories predict the maximum echo amplitudes and the optimum strength parameters. We find that the echo amplitude increases with smaller beam emittance and the asymptotic echo amplitude can exceed half the initial dipole kick amplitude. We show that multiple echoes can be observed provided the dipole kick is large enough. The spectrum of the echo pulse can be used to determine the nonlinear detuning parameter with small amplitude dipole kicks. Simulations are performed to check the theoretical predictions. In the useful ranges of dipole and quadrupole strengths, they are shown to be in reasonable agreement.

  5. Transverse Instabilities in the Fermilab Recycler

    Energy Technology Data Exchange (ETDEWEB)

    Prost, L.R.; Burov, A.; Shemyakin, A.; Bhat, C.M.; Crisp, J.; Eddy, N.; /Fermilab

    2011-07-01

    Transverse instabilities of the antiproton beam have been observed in the Recycler ring soon after its commissioning. After installation of transverse dampers, the threshold for the instability limit increased significantly but the instability is still found to limit the brightness of the antiprotons extracted from the Recycler for Tevatron shots. In this paper, we describe observations of the instabilities during the extraction process as well as during dedicated studies. The measured instability threshold phase density agrees with the prediction of the rigid beam model within a factor of 2. Also, we conclude that the instability threshold can be significantly lowered for a bunch contained in a narrow and shallow potential well due to effective exclusion of the longitudinal tails from Landau damping.

  6. The LHC Transverse Damper (ADT) Performance Specification

    CERN Document Server

    Boussard, Daniel; Linnecar, Trevor Paul R; CERN. Geneva. SPS and LEP Division

    1997-01-01

    The appended document specifies the performance of the transverse damper (ADT) for the LHC. As Annex 1 of the Addendum No.1 to the Protocol of April 18, 1997; it forms part of the 1992 co-operation agreement between CERN and JINR (Dubna, Russia) concerning its participation in the LHC project. The current text is a reprint of the original version. Changes that have been agreed upon are inserted as footnotes.

  7. Sasakian manifolds with purely transversal Bach tensor

    Science.gov (United States)

    Ghosh, Amalendu; Sharma, Ramesh

    2017-10-01

    We show that a (2n + 1)-dimensional Sasakian manifold (M, g) with a purely transversal Bach tensor has constant scalar curvature ≥2 n (2 n +1 ) , equality holding if and only if (M, g) is Einstein. For dimension 3, M is locally isometric to the unit sphere S3. For dimension 5, if in addition (M, g) is complete, then it has positive Ricci curvature and is compact with finite fundamental group π1(M).

  8. Resolution of hydrodynamical equations for transverse expansions

    International Nuclear Information System (INIS)

    Hama, Y.; Pottag, F.W.

    1984-01-01

    The three-dimensional hydrodynamical expansion is treated with a method similar to that of Milekhin, but more explicit. Although in the final stage one have to appeal to numerical calculation, the partial differential equations governing the transverse expansions are treated without transforming them into ordinary equations with an introduction of averaged quantities. It is only concerned with the formalism and the numerical results will be given in the next paper. (Author) [pt

  9. Transversally Lipschitz Harmonic Functions are Lipschitz

    OpenAIRE

    Ravisankar, Sivaguru

    2012-01-01

    Let \\Omega\\subset\\mathbb{R}^n be a bounded domain with C^\\infty boundary. We show that a harmonic function in \\Omega that is Lipschitz along a family of curves transversal to b\\Omega is Lipschitz in \\Omega. The space of Lipschitz functions we consider is defined using the notion of a majorant which is a certain generalization of the power functions t^\\alpha, 0

  10. Nuclear transverse sectional brain function imager

    International Nuclear Information System (INIS)

    Stoddart, H.F.

    1982-01-01

    A transverse radionuclide scan field imaging apparatus comprises a plurality of highly focused closely laterally adjacent collimators arranged inwardly focused in an array that surrounds a scan field of interest. Each collimator is moveable relative to its adjacent collimator. Means are provided for imparting travel to the collimators such that the focal point of each uniformly samples at least one half of the scan field

  11. Vibrations of tube arrays in transversal flow

    International Nuclear Information System (INIS)

    Gibert, R.J.; Doyen, R.

    1981-08-01

    In this study the local forces per unit length acting in a tube in a single row and in bundle have been measured. Their modification by a given harmonic motion of the tube itself or of an adjacent tube has been particularly studied. Some complementary experiments have been performed to extend the whirling coefficient tabulation and also to precise the effect of the upstream velocity profile on the whirling critical velocities [fr

  12. Transverse electron beam diagnostics at REGAE

    International Nuclear Information System (INIS)

    Bayesteh, Shima

    2014-12-01

    The use of high-intensity electron and X-ray pulsed sources allows for the direct observation of atomic motions as they occur. While the production of such high coherent, brilliant, short X-ray pulses requires large-scale and costly accelerator facilities, it is feasible to employ a high-intensity source of electrons by exploiting a more compact design. The Relativistic Electron Gun for Atomic Exploration (REGAE) facility is a small linear accelerator at DESY, Hamburg, equipped with a photocathode radio frequency (RF) gun that produces relativistic ultra-short (<100 fs), low charge (<1 pC) electron bunches of high coherence. By means of time-resolved diffraction experiments, such an electron source can probe ultrafast laser-induced atomic structural changes that occur with a temporal resolution of ∝100 fs. A comprehensive characterization of the electron beam, for every pulse, is of fundamental importance to study the atomic motions with the desired resolution and quality. This thesis reports on the transversal diagnostics of the electron beam with an emphasis on a scintillator-based beam profile monitor. The diagnostics is capable of evaluating the beam parameters such as charge, energy, energy spread and transverse profile, at very low charges and on a shot-to-shot basis. A full characterization of the scintillator's emission, the optical setup and the detector (camera) of the profile monitor is presented, from which an absolute charge calibration of the system is derived. The profile monitor is specially developed to accommodate more applications, such as dark current suppression, overlapping the electron probe and the laser pump within 1 ns accuracy, as well as charge and transverse emittance measurements. For the determination of the transverse emittance two techniques were applied. The first one introduces a new method that exploits a diffraction pattern to measure the emittance, while the second one is based on a version of the Pepper-pot technique. A

  13. The Potential for Ambient Plasma Wave Propulsion

    Science.gov (United States)

    Gilland, James H.; Williams, George J.

    2016-01-01

    A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at

  14. System identification of velocity mechanomyogram measured with a capacitor microphone for muscle stiffness estimation.

    Science.gov (United States)

    Uchiyama, Takanori; Tomoshige, Taiki

    2017-04-01

    A mechanomyogram (MMG) measured with a displacement sensor (displacement MMG) can provide a better estimation of longitudinal muscle stiffness than that measured with an acceleration sensor (acceleration MMG), but the displacement MMG cannot provide transverse muscle stiffness. We propose a method to estimate both longitudinal and transverse muscle stiffness from a velocity MMG using a system identification technique. The aims of this study are to show the advantages of the proposed method. The velocity MMG was measured using a capacitor microphone and a differential circuit, and the MMG, evoked by electrical stimulation, of the tibialis anterior muscle was measured five times in seven healthy young male volunteers. The evoked MMG system was identified using the singular value decomposition method and was approximated with a fourth-order model, which provides two undamped natural frequencies corresponding to the longitudinal and transverse muscle stiffness. The fluctuation of the undamped natural frequencies estimated from the velocity MMG was significantly smaller than that from the acceleration MMG. There was no significant difference between the fluctuations of the undamped natural frequencies estimated from the velocity MMG and that from the displacement MMG. The proposed method using the velocity MMG is thus more advantageous for muscle stiffness estimation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Salud ambiental: conceptos y actividades

    Directory of Open Access Journals (Sweden)

    Ordóñez Gonzalo A.

    2000-01-01

    Full Text Available La finalidad del trabajo es aportar información y propuestas conceptuales que faciliten la tarea de quienes tienen a su cargo la sistematización institucional de la salud ambiental. Se hace un análisis de la noción de "ambiente" para la cual se sugiere una definición, y se examina el lugar de la salud ambiental en el contexto de los problemas ambientales y sus vertientes "verde" y "azul". Se examinan denominaciones equivalentes de salud ambiental y se introducen los servicios de salud ambiental. Se proporcionan varias definiciones y se da la oficial de salud ambiental adoptada por la OMS en Sofía, Bulgaria (1993. A continuación se transcriben las áreas básicas que a la salud ambiental le han asignado diversas organizaciones o reuniones, como la OPS, la OMS, el Programa 21 y otros. A partir de aquí se construye un repertorio bastante completo de áreas y subáreas y se encuentra que todos los listados son, en realidad, una reunión asistemática de tres tipos de constituyentes: determinantes (factores o hechos de la realidad física, procesos (conjuntos de intervenciones y funciones (conjuntos de acciones de gestión, los cuales pueden enfocarse matricialmente y llevan a individualizar actividades de los servicios de salud ambiental. Se proponen unas reglas de operación que permiten, en una especie de álgebra, construir expresiones para especificar con precisión las actividades y sus agregados. De este modo se logra disponer de un lenguaje simbólico común que puede ayudar a la intercomunicación, enseñanza e investigación en el ámbito de la salud ambiental.

  16. Salud ambiental: conceptos y actividades

    Directory of Open Access Journals (Sweden)

    Gonzalo A. Ordóñez

    2000-03-01

    Full Text Available La finalidad del trabajo es aportar información y propuestas conceptuales que faciliten la tarea de quienes tienen a su cargo la sistematización institucional de la salud ambiental. Se hace un análisis de la noción de "ambiente" para la cual se sugiere una definición, y se examina el lugar de la salud ambiental en el contexto de los problemas ambientales y sus vertientes "verde" y "azul". Se examinan denominaciones equivalentes de salud ambiental y se introducen los servicios de salud ambiental. Se proporcionan varias definiciones y se da la oficial de salud ambiental adoptada por la OMS en Sofía, Bulgaria (1993. A continuación se transcriben las áreas básicas que a la salud ambiental le han asignado diversas organizaciones o reuniones, como la OPS, la OMS, el Programa 21 y otros. A partir de aquí se construye un repertorio bastante completo de áreas y subáreas y se encuentra que todos los listados son, en realidad, una reunión asistemática de tres tipos de constituyentes: determinantes (factores o hechos de la realidad física, procesos (conjuntos de intervenciones y funciones (conjuntos de acciones de gestión, los cuales pueden enfocarse matricialmente y llevan a individualizar actividades de los servicios de salud ambiental. Se proponen unas reglas de operación que permiten, en una especie de álgebra, construir expresiones para especificar con precisión las actividades y sus agregados. De este modo se logra disponer de un lenguaje simbólico común que puede ayudar a la intercomunicación, enseñanza e investigación en el ámbito de la salud ambiental.

  17. Transport Mean Free Path for Magneto-Transverse Light Diffusion

    OpenAIRE

    Lacoste, D.; van Tiggelen, B. A.

    1998-01-01

    We derive an expression for the transport mean free path $\\ell^*_\\perp$ associated with magneto-transverse light diffusion for a random collection of Faraday-active Mie scatterers. This expression relates the magneto-transverse diffusion in multiple scattering directly to the magneto-transverse scattering of a single scatterer.

  18. Longitudinal and transverse polarizations in the deep inelastic reactions

    International Nuclear Information System (INIS)

    Bressan, A.

    1996-07-01

    This course is an introduction to the dominant effects of longitudinal and transverse spin in deep inelastic reactions. Only the effects present to the 'leading twist' are attacked. The mass and transverse impulsion of partons are neglected. We will attach to bring out the respective specificities of longitudinal and transverse polarizations. (N.C.)

  19. Evaluation of Transverse Lie at Term by Ultrasonography | Oyinloye ...

    African Journals Online (AJOL)

    Context: Transverse lie at term may have adverse consequences on both the mother and the foetus. Evaluating transverse lie at term by ultrasonography may reduce these adverse consequences and improve both the maternal and fetal outcome. Objectives: To determine predisposing factors to persistent transverse lie at ...

  20. Ultrasonic velocity and elastic moduli of heavy metal tellurite glasses

    Energy Technology Data Exchange (ETDEWEB)

    Afifi, Hesham; Marzouk, Samier

    2003-05-26

    Longitudinal and transverse ultrasonic waves velocities in lead tungsten tellurite glasses have been measured using the pulse-echo method at 5 MHz frequency and at room temperature (300 K). The elastic properties; longitudinal modulus, shear modulus, Young's modulus, bulk modulus and Poisson's ratio together with the microhardness, softening temperature, and Debye temperature are found to be rather sensitive to the glass composition. Information about the structure of the glass can be deduced after calculating the average stretching force constant and the average ring size. A comparison between the experimental elastic moduli data obtained in this study and those calculated theoretically by other models has been discussed.

  1. Ambient Seismic Noise Tomography of a Loess High Bank at Dunaszekcső (Hungary)

    Science.gov (United States)

    Szanyi, Gyöngyvér; Gráczer, Zoltán; Győri, Erzsébet; Kaláb, Zdeněk; Lednická, Markéta

    2016-08-01

    Loess high banks along the right side of the Danube in Hungary are potential subjects of landslides. Small scale ambient seismic noise tomography was used at the Dunaszekcső high bank. The aim of the study was to map near surface velocity anomalies since we assume that the formation of tension cracks—which precede landslides—are represented by low velocities. Mapping Rayleigh wave group velocity distribution can help to image intact and creviced areas and identify the most vulnerable sections. The study area lies at the top of the Castle Hill of Dunaszekcső, which was named after Castellum Lugio, a fortress of Roman origin. The presently active head scarp was formed in April 2011, and our study area was chosen to be at its surroundings. Cross-correlation functions of ambient noise recordings were used to retrieve the dispersion curves, which served as the input of the group velocity tomography. Phase cross-correlation and time-frequency phase weighted stacking was applied to calculate the cross-correlation functions. The average Rayleigh wave group velocity at the loess high bank was found to be 171 ms^{-1}. The group velocity map at a 0.1 s period revealed a low-velocity region, whose location coincides with a highly creviced area, where slope failure takes place along a several meter wide territory. Another low velocity region was found, which might indicate a previously unknown loosened domain. The highest velocities were observed at the supposed remnants of Castellum Lugio.

  2. Publicidade e ambiente: alguns contornos

    OpenAIRE

    Almeida Jr.,Antonio Ribeiro de; Andrade,Thales Novaes de

    2007-01-01

    O presente artigo trata da importância da publicidade na construção social do debate ambiental. Os estudos sobre mídia e ambiente geralmente focam o conteúdo de jornais e programas televisivos, mas nas últimas décadas a publicidade passou a chamar a atenção dos estudiosos sobre o tema. O trabalho procurou discutir a importância do fenômeno do consumo no mundo moderno, e os efeitos sentidos na área ambiental. A seguir são discutidos alguns aspectos do aprimoramento do discurso publicitário no ...

  3. 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

  4. The transverse field Richtmyer-Meshkov instability in magnetohydrodynamics

    KAUST Repository

    Wheatley, V.

    2014-01-10

    The magnetohydrodynamic Richtmyer-Meshkov instability is investigated for the case where the initial magnetic field is unperturbed and aligned with the mean interface location. For this initial condition, the magnetic field lines penetrate the perturbed density interface, forbidding a tangential velocity jump and therefore the presence of a vortex sheet. Through simulation, we find that the vorticity distribution present on the interface immediately after the shock acceleration breaks up into waves traveling parallel and anti-parallel to the magnetic field, which transport the vorticity. The interference of these waves as they propagate causes the perturbation amplitude of the interface to oscillate in time. This interface behavior is accurately predicted over a broad range of parameters by an incompressible linearized model derived presently by solving the corresponding impulse driven, linearized initial value problem. Our use of an equilibrium initial condition results in interface motion produced solely by the impulsive acceleration. Nonlinear compressible simulations are used to investigate the behavior of the transverse field magnetohydrodynamic Richtmyer-Meshkov instability, and the performance of the incompressible model, over a range of shock strengths, magnetic field strengths, perturbation amplitudes and Atwood numbers.

  5. Transverse forces on vortices in superfluids in a periodic potential

    Science.gov (United States)

    Sonin, E. B.

    2016-08-01

    The paper analyzes the transverse forces (the Magnus and the Lorentz forces) on vortices in superfluids put into periodic potentials at T =0 . The case of weak potential and the tight-binding limit described by the Bose-Hubbard model were addressed. The analysis was based on the balance of true momentum and quasimomentum. A special attention was paid to the superfluid close to the superfluid-insulator transition. In this area of the phase diagram the theory predicts the particle-hole symmetry line where the Magnus force changes sign with respect to that expected from the sign of velocity circulation. Our analysis has shown that the magnitude of the Magnus force is a continuous function at crossing the particle-hole symmetry line. This challenges the theory connecting the magnitude of the Magnus force with topological Chern numbers and predicting a jump at crossing this line. Disagreement is explained by the role of intrinsic pinning and guided vortex motion ignored in the topological approach. It is one more evidence that in general topological arguments are not sufficient for derivation of equations of vortex motion.

  6. Kinetic damping of transverse waves in a homogeneous magnetized plasma

    International Nuclear Information System (INIS)

    Lehnert, B.

    1984-12-01

    In a hot magnetized plasma large ion excursions can take place along the magnetic field lines, thereby introducing kinetic effects which cannot be treated in terms of a macroscopic fluid model. This effect is studied for the transverse wave motion of ions and electrons in a homogeneous thermal plasma, being immersed in a homogeneous magnetic field. Strong kinetic wave damping is found to occur when the product ku sub (i) of the wave number k and the ion thermal velocity u sub (i) exceeds the ion gyro frequency ω sub (i). The physical mechanism of this damping originates from large ion excursions and differs from that of Landau damping. The present results suggest that kinetic damping becomes important in hot tokamak plasmas for wave lengths of the order of a few centimeters and less. In high-beta systems, such as the Z-pinch, wave lengths in a large range become affected by kinetic damping, in some case even those which are comparable to the characteristic macroscopic dimensions. This also affects the conditions of plasma stability and plasma high-frequency heating. (Author)

  7. Response of a swirl-stabilized flame to transverse acoustic excitation

    Science.gov (United States)

    O'Connor, Jacqueline

    This work addresses the issue of transverse combustion instabilities in annular gas turbine combustor geometries. While modern low-emissions combustion strategies have made great strides in reducing the production of toxic emissions in aircraft engines and power generation gas turbines, combustion instability remains one of the foremost technical challenges in the development of next generation combustor technology. To that end, this work investigates the response of a swirling flow and swirl-stabilized flame to a transverse acoustic field is using a variety of high-speed laser techniques, especially high-speed particle image velocimetry (PIV) for detailed velocity measurements of this highly unsteady flow phenomenon. Several important issues are addressed. First, the velocity-coupled pathway by which the unsteady velocity field excites the flame is described in great detail. Here, a transfer function approach has been taken to illustrate the various pathways through which the flame is excited by both acoustic and vortical velocity fluctuations. It has been shown that while the direct excitation of the flame by the transverse acoustic field is a negligible effect in most combustor architectures, the coupling between the transverse acoustic mode in the combustor and the longitudinal mode in the nozzle is an important pathway that can result in significant flame response. In this work, the frequency response of this pathway as well as the resulting flame response is measured using PIV and chemiluminescence measurements, respectively. Next, coupling between the acoustic field and the hydrodynamically unstable swirling flow provides a pathway that can lead to significant flame wrinkling by large coherent structures in the flow. Swirling flows display two types of hydrodynamic instability: an absolutely unstable jet and convectively unstable shear layers. The absolute instability of the jet results in vortex breakdown, a large recirculation zone along the centerline of

  8. Spatial and temporal variation of seismic velocity during earthquakes and volcanic eruptions in western Japan: Insight into mechanism for seismic velocity variation

    Science.gov (United States)

    Tsuji, T.; Ikeda, T.; Nimiya, H.

    2017-12-01

    We report spatio-temporal variations of seismic velocity around the seismogenic faults in western Japan. We mainly focus on the seismic velocity variation during (1) the 2016 Off-Mie earthquake in the Nankai subduction zone (Mw5.8) and (2) the 2016 Kumamoto earthquake in Kyushu Island (Mw7.0). We applied seismic interferometry and surface wave analysis to the ambient noise data recorded by Hi-net and DONET seismometers of National Research Institute for Earth Science and Disaster Resilience (NIED). Seismic velocity near the rupture faults and volcano decreased during the earthquake. For example, we observed velocity reduction around the seismogenic Futagawa-Hinagu fault system and Mt Aso in the 2016 Kumamoto earthquake. We also identified velocity increase after the eruptions of Mt Aso. During the 2016 Off-Mie earthquake, we observed seismic velocity variation in the Nankai accretionary prism. After the earthquakes, the seismic velocity gradually returned to the pre-earthquake value. The velocity recovering process (healing process) is caused by several mechanisms, such as pore pressure reduction, strain change, and crack sealing. By showing the velocity variations obtained at different geologic settings (volcano, seismogenic fault, unconsolidated sediment), we discuss the mechanism of seismic velocity variation as well as the post-seismic fault healing process.

  9. Ambient Monitoring Technology Information Center (AMTIC)

    Science.gov (United States)

    This site contains information on ambient air quality monitoring programs, monitoring methods, quality assurance and control procedures, and federal regulations related to ambient air quality monitoring.

  10. Upper crustal structure of Madeira Island revealed from ambient noise tomography

    Science.gov (United States)

    Matos, Catarina; Silveira, Graça; Matias, Luís; Caldeira, Rita; Ribeiro, M. Luísa; Dias, Nuno A.; Krüger, Frank; Bento dos Santos, Telmo

    2015-06-01

    We present the first image of the Madeira upper crustal structure, using ambient seismic noise tomography. 16 months of ambient noise, recorded in a dense network of 26 seismometers deployed across Madeira, allowed reconstructing Rayleigh wave Green's functions between receivers. Dispersion analysis was performed in the short period band from 1.0 to 4.0 s. Group velocity measurements were regionalized to obtain 2D tomographic images, with a lateral resolution of 2.0 km in central Madeira. Afterwards, the dispersion curves, extracted from each cell of the 2D group velocity maps, were inverted as a function of depth to obtain a 3D shear wave velocity model of the upper crust, from the surface to a depth of 2.0 km. The obtained 3D velocity model reveals features throughout the island that correlates well with surface geology and island evolution.

  11. Comunicadores para la informaclon ambiental

    Directory of Open Access Journals (Sweden)

    Luz Marina Cabrera Morillo

    2013-07-01

    Full Text Available La Red Colombiana de Formación Ambiental en convenio con la Corporación Autónoma de los Valles del Sinú y del San Jorge y con el apoyo del Politécnico Grancolombiano, desarrolló un diplomado en Periodismo Ambiental en la ciudad de Montería, Departamento de Córdoba. La experiencia que ha contribuido a fortalecer la construcción de la cultura ambiental en la región; le ha permitido mayor visibilidad a los proyectos de la Corporación y facilitado la participación ciudadana. Este documento presenta el contexto de la formación de los comunicadores para la información ambiental, las características del diplomado y establece algunos de los logros alcanzados.

  12. 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.

  13. Tube bundle vibrations in transversal flow

    International Nuclear Information System (INIS)

    Gibert, R.J.; Sagner, M.

    1978-01-01

    This study gives important information concerning characteristic parameters about lock-in and whirling instability phenomena, in the case of tube arrays. The work is mainly an experimental one though models are also developed: 1) an equilateral pitch bundle (p=1,5 D with D=tube diameter) is tested. Tube damping (epsilon) and first eigenfrequency (f), flow velocity are explored in a large domain. Vibratory level of the tubes are measured and critical points are ploted on the fluidelastic parameters diagram. Several bundles with various usual pitches and arrangements (in line or staggered) are tested. Critical velocities are measured and the whirling instability characteristic coefficient is tabulated. A complementary experiment is made on tube rows with various pitches. This gives valuable informations concerning the look-in domain in VR and A'R diagram. Furthermore this puts in evidence the important effect of a frequency difference between two adjacent tubes on the whirling critical velocity

  14. Generating catalogs of transverse matching solutions

    International Nuclear Information System (INIS)

    Swain, G.; Busch, P.; Burns, M.

    1989-01-01

    Programs such as TRANSPORT or TRACE can find transverse beam matching solutions one at a time when given appropriate starting conditions. In the present work, an algorithm is described which rapidly finds a catalog of approximate transverse beam matching solutions. For a given initial beam, the algorithm finds the gradients of four quadrupole magnets such as to get four Twiss parameters (alpha and beta for horizontal and vertical planes) which are close to a set of desired values at the exit of a constant-energy beam line with no horizontal-vertical cross coupling and no space charge. The beam line may contain bending elements with edge corrections and other elements for which the r matrixes are known. The algorithm transforms the entrance and exit beam specifications to waist specifications, and uses the properties of waist-to-waist transport to reduce the problem from a four dimensional search to a two dimensional search. At the Los Alamos Meson Physics Facility (LAMPF) accelerator, transverse matching is important in the low-energy transport lines (0.75 MeV), where beams from the H + , H/sup /minus//, and polarized H/sup /minus// sources must be tailored for injection into the drift-tube linac; and in the transition region (100 MeV), where the beam from the drift-tube linac is injected into the side-coupled linac. Space charge has significant effects in the low-energy transport, but it is still valuable to get no-space-charge matching solutions as a starting point for solutions with space charge. 2 refs

  15. Subacute transverse myelitis with Lyme profile dissociation

    Directory of Open Access Journals (Sweden)

    Ajjan, Mohammed

    2008-06-01

    Full Text Available Introduction: Transverse myelitis is a very rare neurologic syndrome with an incidence per year of 1-5 per million population. We are presenting an interesting case of subacute transverse myelitis with its MRI (magnetic resonance imaging and CSF (cerebrospinal fluid findings. Case: A 46-year-old African-American woman presented with decreased sensation in the lower extremities which started three weeks ago when she had a 36-hour episode of sore throat. She reported numbness up to the level just below the breasts. Lyme disease antibodies total IgG (immunoglobulin G and IgM (immunoglobulin M in the blood was positive. Antinuclear antibody profile was within normal limits. MRI of the cervical spine showed swelling in the lower cervical cord with contrast enhancement. Cerebrospinal fluid was clear with negative Borrelia Burgdorferi IgG and IgM. Herpes simplex, mycoplasma, coxiella, anaplasma, cryptococcus and hepatitis B were all negative. No oligoclonal bands were detected. Quick improvement ensued after she was given IV Ceftriaxone for 7 days. The patient was discharged on the 8th day in stable condition. She continued on doxycycline for 21 days. Conclusions: Transverse myelitis should be included in the differential diagnosis of any patient presenting with acute or subacute myelopathy in association with localized contrast enhancement in the spinal cord especially if flu-like prodromal symptoms were reported. Lyme disease serology is indicated in patients with neurological symptoms keeping in mind that dissociation in Lyme antibody titers between the blood and the CSF is possible.

  16. A Survey for Transverse Nasal Groove

    Directory of Open Access Journals (Sweden)

    K Pavithran

    1989-01-01

    Full Text Available Out of 3000 consecutive subjects surveyed for the typical lesion of transverse nasal groove, 180 were found to have the characteristic lesions. In LU patients, the floor of the groove was studded with patulous hair follicles, greasy sale and black comedones. The age of the patients varied from 16 to 45 years, the majority belonged to the 20 to 30 age group. Family occurrence of the groove was noted ′in only 7.Seboffhoeic dermatitis, pityriasis versicolor and acne vulgaris were the commonly associated diseases.

  17. Idiopathic intracranial hypertension and transverse sinus stenoses

    DEFF Research Database (Denmark)

    Skyrman, Simon; Fytagoridis, Anders; Andresen, Morten

    2013-01-01

    An 18-year-old woman was diagnosed with idiopathic intracranial hypertension (IIH) and bilateral transverse sinus stenoses (TSS), after presenting with papilledema and decreased visual acuity. Lumbar puncture revealed an opening pressure of >60 cm H2O. MRI showed bilateral TSS believed to be asso...... was inserted since the patient had improved with CSF diversion. MRI verified reopening of the venous sinuses after shunt placement, and the patient remains asymptomatic with no signs of relapse after 3 years of follow-up....

  18. Transverse entanglement migration in Hilbert space

    International Nuclear Information System (INIS)

    Chan, K. W.; Torres, J. P.; Eberly, J. H.

    2007-01-01

    We show that, although the amount of mutual entanglement of photons propagating in free space is fixed, the type of correlations between the photons that determine the entanglement can dramatically change during propagation. We show that this amounts to a migration of entanglement in Hilbert space, rather than real space. For the case of spontaneous parametric down-conversion, the migration of entanglement in transverse coordinates takes place from modulus to phase of the biphoton state and back again. We propose an experiment to observe this migration in Hilbert space and to determine the full entanglement

  19. Interacting dark sector with transversal interaction

    Energy Technology Data Exchange (ETDEWEB)

    Chimento, Luis P.; Richarte, Martín G. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, Pabellón I, Buenos Aires 1428 (Argentina)

    2015-03-26

    We investigate the interacting dark sector composed of dark matter, dark energy, and dark radiation for a spatially flat Friedmann-Robertson-Walker (FRW) background by introducing a three-dimensional internal space spanned by the interaction vector Q and solve the source equation for a linear transversal interaction. Then, we explore a realistic model with dark matter coupled to a scalar field plus a decoupled radiation term, analyze the amount of dark energy in the radiation era and find that our model is consistent with the recent measurements of cosmic microwave background anisotropy coming from Planck along with the future constraints achievable by CMBPol experiment.

  20. Splitting Functions at High Transverse Momentum

    CERN Document Server

    Moutafis, Rhea Penelope; CERN. Geneva. TH Department

    2017-01-01

    Among the production channels of the Higgs boson one contribution could become significant at high transverse momentum which is the radiation of a Higgs boson from another particle. This note focuses on the calculation of splitting functions and cross sections of such processes. The calculation is first carried out on the example $e\\rightarrow e\\gamma$ to illustrate the way splitting functions are calculated. Then the splitting function of $e\\rightarrow eh$ is calculated in similar fashion. This procedure can easily be generalized to processes such as $q\\rightarrow qh$ or $g\\rightarrow gh$.

  1. Asymmetrical transverse structures in nonlinear interferometers

    CERN Document Server

    Romanov, O G

    2003-01-01

    The work presents a novel type of optical instability, which leads to the spontaneous formation of a stationary or pulsating asymmetrical structure in the problem of interaction between two counterpropagating waves in a ring cavity with Kerr-like nonlinearity. Linear stability analysis of interferometer transmission stationary states enabled: (1) to mark out typical bifurcations for this system: self- and cross-modulational instabilities, (2) to determine the range of parameters for which the symmetry breaking of transverse structures and complex temporal behaviour of the light field could be observed. The predictions of linear stability analysis have been verified with numerical modelling of coupled-modes equations.

  2. Transversity GPD in photo- and electroproduction of two vectormesons

    Energy Technology Data Exchange (ETDEWEB)

    Enberg, Rikard; Pire, Bernard; Szymanowski, Lech

    2006-01-17

    The chiral-odd generalized parton distribution (GPD), or transversity GPD, of the nucleon can be accessed experimentally through the photo- or electroproduction of two vector mesons on a polarized nucleon target, {gamma}{sup (*)}N {yields} {rho}{sub 1}{rho}{sub 2}N', where {rho}{sub 1} is produced at large transverse momentum, {rho}{sub 2} is transversely polarized, and the mesons are separated by a large rapidity gap. We predict the cross section for this process for both transverse and longitudinal {rho}{sub 2} production. To this end we propose a model for the transversity GPDH{sub T}(x,{zeta},t), and give an estimate of the relative sizes of the transverse and longitudinal {rho}{sub 2}cross sections. We show that a dedicated experiment at high energy should be able to measure the transversity content of the proton.

  3. MR imaging of alar and transverse atlantal ligament injuries

    Energy Technology Data Exchange (ETDEWEB)

    Echigoya, Naoki; Harata, Seiko; Ueyama, Kazumasa (Hirosaki Univ., Aomori (Japan). School of Medicine); Nakano, Keisuke

    1992-06-01

    Autopsy findings of ligaments of the upper cervical spine were compared with magnetic resonance imaging (MRI) findings. Ligaments were clearly shown as hypointensity on T1-weighted images and proton density images. Transverse images were useful in diagnosing alar and transverse atlantal ligament injuries. When there is a bilateral difference in the alar ligaments, ruptured ligament is suspected. Transverse ligament rupture was shown on interrupted hypointensity and as hyperintensity. MRI was capable of diagnosing alar ligament rupture in 8 of 11 patients, and transverse ligament rupture in all 3 patients. In 2 patients having Jefferson's fracture and injuried atlanoaxial subluxation encountered in the clinical practice, transverse ligament rupture was similarly observed as that in autopsy cases on MR images. Hyperintensity in the transverse ligament rupture area was seen even one year after injury. Injured transverse ligament was seen as swollen hyperintensity on sagittal images; and the hyperintensity was gradually decreased with the process of healing. (N.K.).

  4. Ambient Noise in an Urbanized Tidal Channel

    Science.gov (United States)

    Bassett, Christopher

    levels that shows good agreement with 85% of the temporal data. Bed stresses associated with currents can produce propagating ambient noise by mobilizing sediments. The strength of the tidal currents in northern Admiralty Inlet produces bed stresses in excess of 20 Pa. Significant increases in noise levels at frequencies from 4-30 kHz, with more modest increases noted from 1-4 kHz, are attributed to mobilized sediments. Sediment-generated noise during strong currents masks background noise from other sources, including vessel traffic. Inversions of the acoustic spectra for equivalent grain sizes are consistent with qualitative observations of the seabed composition. Bed stress calculations using log layer, Reynolds stress, and inertial dissipation techniques generally agree well and are used to estimate the shear stresses at which noise levels increase for different grain sizes. Ambient noise levels in one-third octave bands with center frequencies from 1 kHz to 25 kHz are dominated by sediment-generated noise and can be accurately predicted using the near-bed current velocity above a critical threshold. When turbulence is advected over a pressure sensitive transducer, the turbulent pressure fluctuations can be measured as noise, though these pressure fluctuations are not propagating sound and should not be interpreted as ambient noise. Based on measurements in both Admiralty Inlet, Puget Sound and the Chacao Channel, Chile, two models are developed for flow-noise. The first model combined measurements of mean current velocities and turbulence and agrees well with data from both sites. The second model uses scaling arguments to model the flow-noise based solely on the mean current velocity. This model agrees well with the data from the Chacao Channel but performs poorly in Admiralty Inlet, a difference attributed to differences turbulence production mechanisms. At both sites, the spectral slope of flow noise follows a f-3.2 dependence, suggesting partial cancellation of

  5. Ambient Noise Tomography Applied to Nodal Data Sets in Induced Seismicity Regions

    Science.gov (United States)

    Sufri, O.; DeShon, H. R.; Ogwari, P.; Hayward, C.; Magnani, M. B.

    2017-12-01

    We present results of ambient noise tomography performed using nodal datasets with different array apertures and geometries deployed in northern Texas and northern Oklahoma to capture induced earthquakes. We show that ambient noise tomography techniques can be performed on small aperture, oddly shaped array datasets. In northern Texas, the nodal data was collected on 10 Hz single-component vertical sensors that were deployed from the collaboration between SMU and Nodal Seismic. The data was acquired between 25 February and 8 March 2014. First, we compute the cross-correlation between the geophone pairs, which are used as Green's functions to perform ambient noise tomography, and find acceptable results between 0.3-1.0 seconds. We compute the phase velocities for these periods and invert the phase velocities to obtain shear wave velocity structure for up to depths of 200 meters underneath the array. The small aperture of the array (2.6 km x 2.92 km) limits depth resolution. The resulting shear wave velocity model is then used as a shallow velocity constraint to improve double-difference local earthquake tomography using the earthquake data from a co-located local seismic network. We present tomography results aimed at resolving 3D velocity heterogeneity associated with the 2013-2015 Azle-Reno induced earthquake sequence. These techniques are also applied to conduct ambient noise tomography in northern Oklahoma using the IRIS Wavefield Community Experiment data. This data was acquired between 23 June and 20 July 2016 from a larger (6 km x 14 km) aperture array consisting of 5 Hz 3-component nodes. Because the aperture of Wavefield network was larger than the north Texas array, we expect to resolve shear velocity to greater depth and provide 3D information on near surface velocity heterogeneity, and possibly resolve faulting associated with earthquakes beneath the array.

  6. Physical modeling and analysis of P-wave attenuation anisotropy in transversely isotropic media

    Digital Repository Service at National Institute of Oceanography (India)

    Zhu, Y.; Tsvankin, I.; Dewangan, P.; Van Wijk, K.

    phase attenuation coefficient A governed by the Thomsen- style attenuation-anisotropy parameters H9280Q and H9254Q. Whereas the symmetry axis of the angle-dependent coefficient Aprac- tically coincides with that of the velocity function, the magni- tude... and Tsvankin H208492004, 2006H20850 introduced Thomsen-style attenuation parameters H9280Q, H9254Q, and H9253Q de- rived from the Q-matrix for transversely isotropic H20849TIH20850 media and used the new notation to obtain simple approximations for the angle...

  7. Transdimensional, hierarchical, Bayesian inversion of ambient seismic noise: Australia

    Science.gov (United States)

    Crowder, E.; Rawlinson, N.; Cornwell, D. G.

    2017-12-01

    We present models of crustal velocity structure in southeastern Australia using a novel, transdimensional and hierarchical, Bayesian inversion approach. The inversion is applied to long-time ambient noise cross-correlations. The study area of SE Australia is thought to represent the eastern margin of Gondwana. Conflicting tectonic models have been proposed to explain the formation of eastern Gondwana and the enigmatic geological relationships in Bass Strait, which separates Tasmania and the mainland. A geologically complex area of crustal accretion, Bass Strait may contain part of an exotic continental block entrained in colliding crusts. Ambient noise data recorded by an array of 24 seismometers is used to produce a high resolution, 3D shear wave velocity model of Bass Strait. Phase velocity maps in the period range 2-30 s are produced and subsequently inverted for 3D shear wave velocity structure. The transdimensional, hierarchical Bayesian, inversion technique is used. This technique proves far superior to linearised inversion. The inversion model is dynamically parameterised during the process, implicitly controlled by the data, and noise is treated as an inversion unknown. The resulting shear wave velocity model shows three sedimentary basins in Bass Strait constrained by slow shear velocities (2.4-2.9 km/s) at 2-10 km depth. These failed rift basins from the breakup of Australia-Antartica appear to be overlying thinned crust, where typical mantle velocities of 3.8-4.0 km/s occur at depths greater than 20 km. High shear wave velocities ( 3.7-3.8 km/s) in our new model also match well with regions of high magnetic and gravity anomalies. Furthermore, we use both Rayleigh and Love wave phase data to to construct Vsv and Vsh maps. These are used to estimate crustal radial anisotropy in the Bass Strait. We interpret that structures delineated by our velocity models support the presence and extent of the exotic Precambrian micro-continent (the Selwyn Block) that was

  8. 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.

  9. Single transverse spin asymmetry of forward neutrons

    International Nuclear Information System (INIS)

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan; Soffer, J.

    2011-01-01

    We calculate the single transverse spin asymmetry A N (t), for inclusive neutron production in pp collisions at forward rapidities relative to the polarized proton in the energy range of RHIC. Absorptive corrections to the pion pole generate a relative phase between the spin-flip and nonflip amplitudes, leading to a transverse spin asymmetry which is found to be far too small to explain the magnitude of A N observed in the PHENIX experiment. A larger contribution, which does not vanish at high energies, comes from the interference of pion and a 1 -Reggeon exchanges. The unnatural parity of a 1 guarantees a substantial phase shift, although the magnitude is strongly suppressed by the smallness of diffractive πp→a 1 p cross section. We replace the Regge a 1 pole by the Regge cut corresponding to the πρ exchange in the 1 + S state. The production of such a state, which we treat as an effective pole a, forms a narrow peak in the 3π invariant mass distribution in diffractive πp interactions. The cross section is large, so one can assume that this state saturates the spectral function of the axial current and we can determine its coupling to nucleons via the partially conserved axial-vector-current constraint Goldberger-Treiman relation and the second Weinberg sum rule. The numerical results of the parameter-free calculation of A N are in excellent agreement with the PHENIX data.

  10. Transverse Field Effect in Fluxgate Sensors

    DEFF Research Database (Denmark)

    Brauer, Peter; Merayo, José M.G.; Nielsen, Otto V

    1997-01-01

    A model of the fluxgate magnetometer based on the field interactions in the fluxgate core has been derived. The non-linearity of the ringcore sensors due to large uncompensated fields transverse to the measuring axis are calculated and compared with measurements. Measurements of the non-linearity......A model of the fluxgate magnetometer based on the field interactions in the fluxgate core has been derived. The non-linearity of the ringcore sensors due to large uncompensated fields transverse to the measuring axis are calculated and compared with measurements. Measurements of the non......-linearity are made with a spectrum analyser, measuring the higher harmonics of an applied sinusoidal field. For a sensor with a permalloy ringcore of 1" in diameter the deviation from linearity is measured to about 15 nTp-p in the earth's field and the measurements are shown to fit well the calculations. Further......, the measurements and the calculations are also compared with a calibration model of the fluxgate sensor onboard the "MAGSAT" satellite. The later has a deviation from linearity of about 50 nTp-p but shows basically the same form of non-linearity as the measurements....

  11. Ambient Seismic Imaging of Hydraulically Active Fractures at km Depths

    Science.gov (United States)

    Malin, P. E.; Sicking, C.

    2017-12-01

    Streaming Depth Images of ambient seismic signals using numerous, densely-distributed, receivers have revealed their connection to hydraulically active fractures at 0.5 to 5 km depths. Key for this type of imaging is very high-fold stacking over both multiple receives and periods of a few hours. Also important is suppression of waveforms from fixed, repeating sources such as pumps, generators, and traffic. A typical surface-based ambient SDI survey would use a 3D seismic receiver grid. It would have 1,000 to 4,000 uniformly distributed receivers at a density of 50/km2over the target. If acquired by borehole receivers buried 100 m deep, the density can be dropped by an order of magnitude. We show examples of the acquisition and signal processing scenarios used to produce the ambient images. (Sicking et al., SEG Interpretation, Nov 2017.) While the fracture-fluid source connection of SDI has been verified by drilling and various types of hydraulic tests, the precise nature of the signal's origin is not clear. At the current level of observation, the signals do not have identifiable phases, but can be focused using P wave velocities. Suggested sources are resonances of pressures fluctuations in the fractures, or small, continuous, slips on fractures surfaces. In either case, it appears that the driving mechanism is tectonic strain in an inherently unstable crust. Solid earth tides may enhance these strains. We illustrate the value of the ambient SDI method in its industrial application by showing case histories from energy industry and carbon-capture-sequestration projects. These include ambient images taken before, during, and after hydraulic treatments in un-conventional reservoirs. The results show not only locations of active fractures, but also their time responses to stimulation and production. Time-lapse ambient imaging can forecast and track events such as well interferences and production changes that can result from nearby treatments.

  12. Robotic transverse colectomy for mid-transverse colon cancer: surgical techniques and oncologic outcomes.

    Science.gov (United States)

    Jung, Kyung Uk; Park, Yoonah; Lee, Kang Young; Sohn, Seung-Kook

    2015-06-01

    Robot-assisted surgery for colon cancer has been reported in many studies, most of which worked on right and/or sigmoid colectomy. The aim of this study was to report our experience of robotic transverse colectomy with an intracorporeal anastomosis, provide details of the surgical technique, and present the theoretical benefits of the procedure. This is a retrospective review of prospectively collected data of robotic surgery for colorectal cancer performed by a single surgeon between May 2007 and February 2011. Out of 162 consecutive cases, we identified three robotic transverse colectomies, using a hand-sewn intracorporeal anastomosis. Two males and one female underwent transverse colectomies for malignant or premalignant disease. The mean docking time, time spent using the robot, and total operative time were 5, 268, and 307 min, respectively. There were no conversions to open or conventional laparoscopic technique. The mean length of specimen and number of lymph nodes retrieved were 14.1 cm and 6.7, respectively. One patient suffered from a wound seroma and recovered with conservative management. The mean hospital stay was 8.7 days. After a median follow-up of 72 months, there were no local or systemic recurrences. Robotic transverse colectomy seems to be a safe and feasible technique. It may minimize the necessity of mobilizing both colonic flexures, with facilitated intracorporeal hand-sewn anastomosis. However, further prospective studies with a larger number of patients are required to draw firm conclusions.

  13. Single transverse-spin asymmetry in high transverse momentum pion production in pp collisions

    DEFF Research Database (Denmark)

    Kouvaris, Christoforos; Qiu, Jian-Wei; Vogelsang, Werner

    2006-01-01

    We study the single-spin (left-right) asymmetry in single-inclusive pion production in hadronic scattering. This asymmetry is power-suppressed in the transverse momentum of the produced pion and can be analyzed in terms of twist-three parton correlation functions in the proton. We present new...

  14. Dynamic analysis of slab track on multi-layered transversely isotropic saturated soils subjected to train loads

    Science.gov (United States)

    Zhan, Yongxiang; Yao, Hailin; Lu, Zheng; Yu, Dongming

    2014-12-01

    The dynamic responses of a slab track on transversely isotropic saturated soils subjected to moving train loads are investigated by a semi-analytical approach. The track model is described as an upper Euler beam to simulate the rails and a lower Euler beam to model the slab. Rail pads between the rails and slab are represented by a continuous layer of springs and dashpots. A series of point loads are formulated to describe the moving train loads. The governing equations of track-ground systems are solved using the double Fourier transform, and the dynamic responses in the time domain are obtained by the inverse Fourier transform. The results show that a train load with high velocity will generate a larger response in transversely isotropic saturated soil than the lower velocity load, and special attention should be paid on the pore pressure in the vicinity of the ground surface. The anisotropic parameters of a surface soil layer will have greater influence on the displacement and excess pore water pressure than those of the subsoil layer. The traditional design method taking ground soil as homogeneous isotropic soil is unsafe for the case of RE < 1 and RG < 1, so a transversely isotropic foundation model is of great significance to the design for high train velocities.

  15. Effects of shale and contaminants on (VS/VP) ratios in transversely - isotropic geology

    International Nuclear Information System (INIS)

    Benson, A.K.

    1994-01-01

    The mechanical properties of rocks and soils can be calculated from the shear-wave velocity, V s , the compressional-wave velocity, V p , and the density, or from (V S /V P ) ratios and the density. Therefore, determination of (V S /V P ) ratios is an important tool to assist with lithological identification and many associated applications. In most geologic settings, mixtures of different materials are quite common, and it is important to understand the effect of thin laminations on measured (V S /V P ) ratios. An equation is derived for (V S /V P ) in transversely-isotropic materials. It is found that even small amounts of a second component, such as 10% shale, can change (V S /V P ) ratios significantly from that of a pure end member, such as sandstone. Case studies will illustrate some practical applications. 32 refs., 6 figs

  16. In Vivo 3-D Vector Velocity Estimation with Continuous Data

    DEFF Research Database (Denmark)

    Holbek, Simon; Pihl, Michael Johannes; Ewertsen, Caroline

    2015-01-01

    In this study, a method for estimating 3-D vector velocities at very high frame rate using continuous data acquisition is presented. An emission sequence was designed to acquire real-time continuous data in one plane. The transverse oscillation (TO) method was used to estimate 3-D vector flow...... in a carotid flow phantom and in vivo in the common carotid artery of a healthy 27-year old female. Based on the out-of-plane velocity component during four periodic cycles, estimated flow rates in an experimental setup was 2.96 ml/s ± 0.35 ml/s compared to the expected 3.06 ml/s ± 0.09 ml/s. In the in vivo...... measurements, three heart cycles acquired at 2.1 kHz showed peak out-of-plane velocities of 83 cm/s, 87 cm/s and 90 cm/s in agreement with the 92 cm/s found with spectral Doppler. Mean flow rate was estimated to 257 ml/min. The results demonstrate that accurate real-time 3- D vector velocities can be obtained...

  17. The drift velocity monitoring system of the CMS barrel muon chambers

    Science.gov (United States)

    Altenhöfer, Georg; Hebbeker, Thomas; Heidemann, Carsten; Reithler, Hans; Sonnenschein, Lars; Teyssier, Daniel

    2018-04-01

    The drift velocity is a key parameter of drift chambers. Its value depends on several parameters: electric field, pressure, temperature, gas mixture, and contamination, for example, by ambient air. A dedicated Velocity Drift Chamber (VDC) with 1-L volume has been built at the III. Phys. Institute A, RWTH Aachen, in order to monitor the drift velocity of all CMS barrel muon Drift Tube chambers. A system of six VDCs was installed at CMS and has been running since January 2011. We present the VDC monitoring system, its principle of operation, and measurements performed.

  18. The drift velocity monitoring system of the CMS barrel muon chambers

    CERN Document Server

    Altenhoefer, Georg Friedrich; Heidemann, Carsten Andreas; Reithler, Hans; Sonnenschein, Lars; Teyssier, Daniel Francois

    2017-01-01

    The drift velocity is a key parameter of drift chambers. Its value depends on several parameters: electric field, pressure, temperature, gas mixture, and contamination, for example, by ambient air. A dedicated Velocity Drift Chamber (VDC) with 1-L volume has been built at the III. Phys. Institute A, RWTH Aachen, in order to monitor the drift velocity of all CMS barrel muon Drift Tube chambers. A system of six VDCs was installed at CMS and has been running since January 2011. We present the VDC monitoring system, its principle of operation, and measurements performed.

  19. La educación ambiental como base cultural y estrategia para el desarrollo sostenible

    Directory of Open Access Journals (Sweden)

    Carlos Severiche-Sierra

    2016-05-01

    Full Text Available En la actualidad se habla de educación ambiental como el medio más efectivo para concienciar a la población sobre la necesidad de preservar el ambiente con miras a lograr una mejor calidad de vida en las generaciones actuales y por venir. Pese a los esfuerzos por conservar los recursos naturales no se ha podido frenar el deterioro ambiental, debido, posiblemente, a que no logramos tener conciencia y actitud de respeto hacia la naturaleza. Se hizo una revisión sobre las investigaciones más recientes acerca de la trascendencia de la educación ambiental como base para optimizar la cultura presente y futura. El presente artículo de revisión tiene como principal analizar cualitativamente la literatura científica disponible en las bases de datos Science Direct, Scielo, Redalyc y páginas Web oficiales, empleando como palabras de búsqueda: ambiente, cultura, educación, sociedad, sostenibilidad. Se obtuvo información pertinente relacionada con el objetivo propuesto, la cual se presenta en 3 secciones: la educación ambiental, un eje transversal, cultura y educación ambiental y educación para el desarrollo sostenible, estableciendo además la dimensión ambiental como estrategia para el avance en aspectos sociales, económicos y su contribución al desarrollo sostenible de nuestra sociedad. La educación ambiental es pilar fundamental de la generación de cambios de actitud y aptitud y de lograr un equilibrio entre el ser humano y su entorno. Se requiere del apoyo de casi todas las disciplinas, por lo que la resolución de los problemas ambientales debe contar con la participación activa de un amplio conjunto de personas e instituciones.

  20. 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

  1. Conhecimento, interdisciplinaridade e Psicologia Ambiental

    Directory of Open Access Journals (Sweden)

    Ombretta Romice

    2005-01-01

    Full Text Available Responde às questões - como os métodos da Psicologia Ambiental devem ser discutidos em um enquadramento interdisciplinar; a Psicologia Ambiental pede alguma abordagem metodológica especial; como a intervenção ambiental é determinada pela interdisciplinaridade; quais são estas disciplinas e como elas se relacionam entre si - baseando-se em experiências profissionais como orientador em um projeto com comunidade, com habitação popular e exclusão social em vários países da Europa, e como consultora. Conclui que as abordagens usadas pelas diferentes profissões são muito separadas, e que apenas metas comuns não são suficientes, sendo também necessários um treino conjunto e identidade de valores.

  2. Ambient Seismic Noise Tomography of a Loess High Bank at Dunaszekcső (Hungary)

    Czech Academy of Sciences Publication Activity Database

    Szanyi, G.; Gráczer, Z.; Györi, E.; Kaláb, Zdeněk; Lednická, Markéta

    2016-01-01

    Roč. 173, č. 8 (2016), s. 2913-2928 ISSN 0033-4553 Institutional support: RVO:68145535 Keywords : seismic interferometry * ambient noise * group velocity * tomography * landslide * high bank Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.591, year: 2016 http://link.springer.com/article/10.1007/s00024-016-1304-1

  3. Significance of geological units of the Bohemian Massif, Czech Republic, as seen by ambient noise interferometry

    Czech Academy of Sciences Publication Activity Database

    Růžek, Bohuslav; Valentová, L.; Gallovič, F.

    2016-01-01

    Roč. 173, č. 5 (2016), s. 1663-1682 ISSN 0033-4553 R&D Projects: GA ČR GAP210/12/2336; GA MŠk LM2010008 Institutional support: RVO:67985530 Keywords : ambient noise * geological units * Bohemian Massif * velocity model Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.591, year: 2016

  4. The crustal structure beneath The Netherlands derived from ambient seismic noise

    NARCIS (Netherlands)

    Yudistira, Tedi; Paulssen, Hanneke; Trampert, Jeannot

    2017-01-01

    This work presents the first comprehensive 3-D model of the crust beneath The Netherlands. To obtain this model, we designed the NARS-Netherlands project, a dense deployment of broadband stations in the area. Rayleigh and Love wave group velocity dispersion was measured from ambient noise

  5. The crustal structure beneath the Netherlands inferred from ambient seismic noise

    NARCIS (Netherlands)

    Yudistira, T.

    2015-01-01

    A 3-D shear velocity model of the crust beneath the Netherlands is determined from fundamental mode Rayleigh and Love wave group measurements derived from ambient seismic noise recordings. The data are obtained from a temporary array of broad-band seismometers in and around the Netherlands (the

  6. Transversal expansion study in the Landau hydrodynamic

    International Nuclear Information System (INIS)

    Pottag, F.W.

    1984-01-01

    The system of equations in the frame of Landau's hydrodynamical model for multiparticle production at high energies is studied. Taking as a first approximation the one-dimensional exact due to Khalatnikov, and a special set of curvilinear coordinates, the radial part is separated from the longitudinal one in the equations of motion, and a system of partial differential equations (non-linear, hyperbolic) is obtained for the radial part. These equations are solved numerically by the method of caracteristics. The hydrodynamical variables are obtained over all the three-dimensional-flow region as well as its variation with the mass of the initially expanding system. Both, the transverse rapidity distribution of the fluid and the inclusive particle distribution at 90 0 in the center of mass system, are calculated. The last one is compared with recent experimental data. (author) [pt

  7. Potentials for transverse trace-free tensors

    International Nuclear Information System (INIS)

    Conboye, Rory; Murchadha, Niall Ó

    2014-01-01

    In constructing and understanding initial conditions in the 3 + 1 formalism for numerical relativity, the transverse and trace-free (TT) part of the extrinsic curvature plays a key role. We know that TT tensors possess two degrees of freedom per space point. However, finding an expression for a TT tensor depending on only two scalar functions is a non-trivial task. Assuming either axial or translational symmetry, expressions depending on two scalar potentials alone are derived here for all TT tensors in flat 3-space. In a more general spatial slice, only one of these potentials is found, the same potential given in (Baker and Puzio 1999 Phys. Rev. D 59 044030) and (Dain 2001 Phys. Rev. D 64 124002), with the remaining equations reduced to a partial differential equation, depending on boundary conditions for a solution. As an exercise, we also derive the potentials which give the Bowen-York curvature tensor in flat space. (paper)

  8. Borel resummation of transverse momentum distributions

    CERN Document Server

    Bonvini, Marco; Ridolfi, Giovanni

    2009-01-01

    We present a new prescription for the resummation of contributions due to soft gluon emission to the trasverse momentum distribution of processes such as Drell-Yan production in hadronic collisions. We show that familiar difficulties in obtaining resummed results as a function of transverse momentum starting from impact-parameter space resummation are related to the divergence of the perturbative expansion of the momentum-space result. We construct a resummed expression by Borel resummation of this divergent series, removing the divergence in the Borel inversion through the inclusion of a suitable higher twist term. The ensuing resummation prescription is free of numerical instabilities, is stable upon the inclusion of subleading terms, and the original divergent perturbative series is asymptotic to it. We compare our results to those obtained using alternative prescriptions, and discuss the ambiguities related to the resummation procedure.

  9. PEP-II Transverse Feedback Electronics Upgrade

    International Nuclear Information System (INIS)

    Weber, J.; Chin, M.; Doolittle, L.; Akre, R.

    2005-01-01

    The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx(R) ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design

  10. The transverse damper system for RHIC

    International Nuclear Information System (INIS)

    Xu, J.; Claus, J.; Raka, E.; Ruggiero, A.G.; Shea, T.J.

    1991-01-01

    If the beam is injected with errors x c , x' c (or y c , y' c ) with respect to the closed orbit or disturbed by transverse instabilities, it will execute coherent oscillations and will be diluted in betatron phase space within a time interval of about 1/Δν turns, even if it is properly matched to the focusing characteristics of the lattice, unless there is an effective damper system to prevent this. Here Δν is the tune spread in the beam. Such a damper will not prevent dilution due to mismatches. Without such a damper the emittance of the beam will ultimately develop to a properly centered matched ellipse with an area ε in phase space that is larger than that of the injected one ε 0 which is also matched but off-centered by x c and x' c

  11. Transverse Momentum Correlations in Hadronic Z decays

    CERN Document Server

    Buskulic, Damir; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Odier, P; Pietrzyk, B; Casado, M P; Chmeissani, M; Crespo, J M; Delfino, M C; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Orteu, S; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Alemany, R; Bazarko, A O; Bonvicini, G; Bright-Thomas, P G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Lutters, G; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Mir, L M; Moneta, L; Oest, T; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rizzo, G; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Schmidt, M; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Abbaneo, D; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Moutoussi, A; Nash, J; Sedgbeer, J K; Stacey, A M; Williams, M D; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Williams, M I; Galla, A; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Konstantinidis, N P; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Ragusa, F; Bauer, C; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Schune, M H; Simion, S; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Verdini, P G; Walsh, J; Blair, G A; Bryant, L M; Cerutti, F; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Köksal, A; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1997-01-01

    Using data obtained with the ALEPH detector at the Z resonance, a measure based on transverse momentum is shown to exhibit a correlation between the two halves of a hadronic event which cannot be explained by energy-momentum conservation, flavour conservation, the imposition of an event axis or imperfect event reconstruction. Two possible explanations based on Monte Carlo models are examined: a) ARIADNE, with the correlation forming early in the parton shower and with the transition from partons to hadrons playing only a minor part; b) JETSET, with the correlation forming at the fragmentation stage. A correlation technique based on a jet cluster analysis is used to make a comparison of the models with the data. It is concluded that both non-perturbative and perturbative effects make important contributions to the observed correlation.

  12. A tilted transversely isotropic slowness surface approximation

    KAUST Repository

    Stovas, A.

    2012-05-09

    The relation between vertical and horizontal slownesses, better known as the dispersion relation, for transversely isotropic media with a tilted symmetry axis (TTI) requires solving a quartic polynomial equation, which does not admit a practical explicit solution to be used, for example, in downward continuation. Using a combination of the perturbation theory with respect to the anelliptic parameter and Shanks transform to improve the accuracy of the expansion, we develop an explicit formula for the vertical slowness that is highly accurate for all practical purposes. It also reveals some insights into the anisotropy parameter dependency of the dispersion relation including the low impact that the anelliptic parameter has on the vertical placement of reflectors for a small tilt in the symmetry angle. © 2012 European Association of Geoscientists & Engineers.

  13. Transversal Dirac families in Riemannian foliations

    International Nuclear Information System (INIS)

    Glazebrook, J.F.; Kamber, F.W.

    1991-01-01

    We describe a family of differential operators parametrized by the transversal vector potentials of a Riemannian foliation relative to the Clifford algebra of the foliation. This family is non-elliptic but in certain ways behaves like a standard Dirac family in the absolute case as a result of its elliptic-like regularity properties. The analytic and topological indices of this family are defined as elements of K-theory in the parameter space. We indicate how the cohomology of the parameter space is described via suitable maps to Fredholm operators. We outline the proof of a theorem of Vafa-Witten type on uniform bounds for the eigenvalues of this family using a spectral flow argument. A determinant operator is also defined with the appropriate zeta function regularization dependent on the codimension of the foliation. With respect to a generalized coupled Dirac-Yang-Mills system, we indicate how chiral anomalies are located relative to the foliation. (orig.)

  14. PEP-II Transverse Feedback Electronics Upgrade

    CERN Document Server

    Weber, Jonah; Chin, Michael; Doolittle, Lawrence

    2005-01-01

    The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx® ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design.

  15. Transverse Beam Profile Measurements Using Optical Methods

    CERN Document Server

    Peters, A; Weiss, A; Bank, A

    2001-01-01

    Two different systems are currently under development at GSI's heavy ion facility to measure transverse beam profiles using optical emitters. At the GSI-LINAC for energies up to 15 MeV/u residual gas fluorescence is investigated for pulsed high current beams. The fluorescence of N2 is monitored by an image intensified CCD camera. For all ion species with energies above 50 MeV/u slowly extracted from the synchrotron SIS a classical viewing screen system is used. Three different target materials have been investigated and their behavior concerning efficiency, saturation and timing performance is evaluated. Both systems (will) use CCD cameras with a digital read out using the IEEE 1394 standard.

  16. Transverse Matching Techniques for the SNS Linac

    CERN Document Server

    Jeon Dong Oh; Danilov, Viatcheslav V

    2005-01-01

    It is crucial to minimize beam loss and machine activation by obtaining optimal transverse matching for a high-intensity linear accelerator such as the Spallation Neutron Source linac. For matching the Drift Tube Linac (DTL) to Coupled Cavity Linac (CCL), there are four wire-scanners installed in series in CCL module 1 as proposed by the author.* A series of measurements was conducted to minimize envelope breathing and the results are presented here. As an independent approach, Chu et al is developing an application based on another technique by estimating rms emittance using the wire scanner profile data.** For matching the Medium Energy Beam Transport Line to the DTL, a technique of minimizing rms emittance was used and emittance data show that tail is minimized as well.

  17. Transverse magnetization and giant magnetoimpedance in amorphous ribbons

    International Nuclear Information System (INIS)

    Orue, I.; Garcia-Arribas, A.; Saad, A.; Cos, D. de; Barandiaran, J.M.

    2005-01-01

    In the classical approach giant magnetoimpedance (GMI) is driven by the transverse permeability of the sample, as excited by the current flowing through it. Transverse permeability is usually taken as a constant, while detailed magnetization processes are important for the interpretation of GMI data. In most cases the transverse permeability (or magnetization) is only guessed by looking at the longitudinal magnetization curve and direct determinations of such parameter are scarce in the literature. In this work we report on the operation of a simple setup which provides the transverse magnetization of amorphous ribbons as a function of the current intensity flowing through it, by means of the magnetooptical kerr effect (MOKE). The system has been tested on low magnetostriction amorphous ribbons of very soft character with both longitudinal and transverse anisotropy. The transverse magnetization as a function of both the current and a DC longitudinal field applied, was compared with magneto impedance measurements

  18. Missing transverse energy performance of the CMS detector

    Energy Technology Data Exchange (ETDEWEB)

    Chatrchyan, Serguei [Yerevan Physics Inst. (Armenia); et al.

    2011-09-01

    During 2010 the LHC delivered pp collisions with a centre-of-mass energy of 7 TeV. In this paper, the results of comprehensive studies of missing transverse energy as measured by the CMS detector are presented. The results cover the measurements of the scale and resolution for missing transverse energy, and the effects of multiple pp interactions within the same bunch crossings on the scale and resolution. Anomalous measurements of missing transverse energy are studied, and algorithms for their identification are described. The performances of several reconstruction algorithms for calculating missing transverse energy are compared. An algorithm, called missing-transverse-energy significance, which estimates the compatibility of the reconstructed missing transverse energy with zero, is described, and its performance is demonstrated.

  19. Missing transverse energy performance of the CMS detector

    CERN Document Server

    Chatrchyan, Serguei; Sirunyan, Albert M; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hammer, Josef; Haensel, Stephan; Hoch, Michael; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Krammer, Manfred; Liko, Dietrich; Mikulec, Ivan; Pernicka, Manfred; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Teischinger, Florian; Wagner, Philipp; Waltenberger, Wolfgang; Walzel, Gerhard; Widl, Edmund; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Benucci, Leonardo; De Wolf, Eddi A; Janssen, Xavier; Maes, Joris; Maes, Thomas; Mucibello, Luca; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Selvaggi, Michele; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Devroede, Olivier; Gonzalez Suarez, Rebeca; Kalogeropoulos, Alexis; Maes, Michael; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Charaf, Otman; Clerbaux, Barbara; De Lentdecker, Gilles; Dero, Vincent; Gay, Arnaud; Hammad, Gregory Habib; Hreus, Tomas; Marage, Pierre Edouard; Thomas, Laurent; Vander Velde, Catherine; Vanlaer, Pascal; Adler, Volker; Cimmino, Anna; Costantini, Silvia; Grunewald, Martin; Klein, Benjamin; Lellouch, Jérémie; Marinov, Andrey; Mccartin, Joseph; Ryckbosch, Dirk; Thyssen, Filip; Tytgat, Michael; Vanelderen, Lukas; Verwilligen, Piet; Walsh, Sinead; Zaganidis, Nicolas; Basegmez, Suzan; Bruno, Giacomo; Caudron, Julien; Ceard, Ludivine; Cortina Gil, Eduardo; De Favereau De Jeneret, Jerome; Delaere, Christophe; Favart, Denis; Giammanco, Andrea; Grégoire, Ghislain; Hollar, Jonathan; Lemaitre, Vincent; Liao, Junhui; Militaru, Otilia; Ovyn, Severine; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Schul, Nicolas; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Alves, Gilvan; De Jesus Damiao, Dilson; Pol, Maria Elena; Henrique Gomes E Souza, Moacyr; Carvalho, Wagner; Melo Da Costa, Eliza; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Mundim, Luiz; Nogima, Helio; Oguri, Vitor; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Silva Do Amaral, Sheila Mara; Sznajder, Andre; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Tomei, Thiago; De Moraes Gregores, Eduardo; Lagana, Caio; Da Cunha Marinho, Franciole; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Darmenov, Nikolay; Dimitrov, Lubomir; Genchev, Vladimir; Iaydjiev, Plamen; Piperov, Stefan; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Tcholakov, Vanio; Trayanov, Rumen; Vankov, Ivan; Dimitrov, Anton; Hadjiiska, Roumyana; Karadzhinova, Aneliya; Kozhuharov, Venelin; Litov, Leander; Mateev, Matey; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Meng, Xiangwei; Tao, Junquan; Wang, Jian; Wang, Jian; Wang, Xianyou; Wang, Zheng; Xiao, Hong; Xu, Ming; Zang, Jingjing; Zhang, Zhen; Ban, Yong; Guo, Shuang; Guo, Yifei; Li, Wenbo; Mao, Yajun; Qian, Si-Jin; Teng, Haiyun; Zhang, Linlin; Zhu, Bo; Zou, Wei; Cabrera, Andrés; Gomez Moreno, Bernardo; Ocampo Rios, Alberto Andres; Osorio Oliveros, Andres Felipe; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Lelas, Karlo; Plestina, Roko; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Dzelalija, Mile; Brigljevic, Vuko; Duric, Senka; Kadija, Kreso; Morovic, Srecko; Attikis, Alexandros; Galanti, Mario; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Finger, Miroslav; Finger Jr, Michael; Khalil, Shaaban; Mahmoud, Mohammed; Radi, Amr; Hektor, Andi; Kadastik, Mario; Müntel, Mait; Raidal, Martti; Rebane, Liis; Azzolini, Virginia; Eerola, Paula; Fedi, Giacomo; Czellar, Sandor; Härkönen, Jaakko; Heikkinen, Mika Aatos; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Ungaro, Donatella; Wendland, Lauri; Banzuzi, Kukka; Korpela, Arja; Tuuva, Tuure; Sillou, Daniel; Besancon, Marc; Choudhury, Somnath; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Ferri, Federico; Ganjour, Serguei; Gentit, François-Xavier; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Locci, Elizabeth; Malcles, Julie; Marionneau, Matthieu; Millischer, Laurent; Rander, John; Rosowsky, André; Shreyber, Irina; Titov, Maksym; Verrecchia, Patrice; Baffioni, Stephanie

    2011-01-01

    During 2010 the LHC delivered pp collisions with a centre-of-mass energy of 7 TeV. In this paper, the results of comprehensive studies of missing transverse energy as measured by the CMS detector are presented. The results cover the measurements of the scale and resolution for missing transverse energy, and the effects of multiple pp interactions within the same bunch crossings on the scale and resolution. Anomalous measurements of missing transverse energy are studied, and algorithms for their identification are described. The performances of several reconstruction algorithms for calculating missing transverse energy are compared. An algorithm, called missing-transverse-energy significance, which estimates the compatibility of the reconstructed missing transverse energy with zero, is described, and its performance is demonstrated.

  20. Ambient-noise tomography of Katla volcano, south Iceland

    Science.gov (United States)

    Jeddi, Zeinab; Gudmundsson, Olafur; Tryggvason, Ari

    2017-11-01

    A shear-wave velocity model of subglacial Katla volcano, southern Iceland, has been developed using ambient seismic noise tomography based on data from a temporary network operating between May 2011 and August 2013 and permanent stations around the volcano. Phase-velocity dispersion curves were obtained using cross-correlations of vertical components of 136 station pairs and non-linearly inverted for phase-velocity maps between 1.7 and 7.5 s. Local dispersion curves were inverted for shear-velocity variation with depth using a grid search imposing a fixed ice layer at the top. The resulting one-dimensional (1-D) velocity models were combined to obtain a pseudo three-dimensional (3-D) model with estimated lateral resolution of 8 km and depth resolution varying from close to 1 km near the surface to about 8 km at 10 km depth. Shear wave velocities are generally higher within the Katla central volcano than in its surroundings. The most striking feature of the model is a high-velocity anomaly beneath the caldera at > 6 km depth interpreted to be due to cumulates resulting from differentiation of shallower magma intrusions and remelting of subsiding upper crust. No shallow low-velocity anomaly is resolved beneath the central caldera, but a low-velocity region is found at 2-4 km depth beneath the western half of the caldera. VP/VS ratios, estimated from average velocity-depth profiles from surface-wave data and higher frequency P-wave data, are anomalously high (> 1.9) compared to average Icelandic crust, particularly in the top 2-3 km. This is argued not to be an artifact due to lateral refraction or topography. Instead, this anomaly could be explained as an artifact caused by velocity dispersion due to attenuation and a difference in frequency content, and possibly to a degree by the compositional difference between the transalkalic Fe-Ti basalts of Katla and average tholeiitic Icelandic crust.

  1. Source-to-target simulation of simultaneous longitudinal and transverse focusing of heavy ion beams

    Directory of Open Access Journals (Sweden)

    D. R. Welch

    2008-06-01

    Full Text Available Longitudinal bunching factors in excess of 70 of a 300-keV, 27-mA K^{+} ion beam have been demonstrated in the neutralized drift compression experiment [P. K. Roy et al., Phys. Rev. Lett. 95, 234801 (2005PRLTAO0031-900710.1103/PhysRevLett.95.234801] in rough agreement with particle-in-cell source-to-target simulations. A key aspect of these experiments is that a preformed plasma provides charge neutralization of the ion beam in the last one meter drift region where the beam perveance becomes large. The simulations utilize the measured ion source temperature, diode voltage, and induction-bunching-module voltage waveforms in order to determine the initial beam longitudinal phase space which is critical to accurate modeling of the longitudinal compression. To enable simultaneous longitudinal and transverse compression, numerical simulations were used in the design of the solenoidal focusing system that compensated for the impact of the applied velocity tilt on the transverse phase space of the beam. Complete source-to-target simulations, that include detailed modeling of the diode, magnetic transport, induction bunching module, and plasma neutralized transport, were critical to understanding the interplay between the various accelerator components in the experiment. Here, we compare simulation results with the experiment and discuss the contributions to longitudinal and transverse emittance that limit the final compression.

  2. PKU-RBRC Workshop on Transverse Spin

    Energy Technology Data Exchange (ETDEWEB)

    Avakian,H.; Bunce, G.; Yuan, F.

    2008-06-30

    Understanding the structure of the nucleon is a fundamental question in subatomic physics, and it has been under intensive investigation for the last several years. Modern research focuses in particular on the spin structure of the nucleon. Experimental and theoretical investigations worldwide over the last few decades have established that, contrary to nave quark model expectations, quarks carry only about 30% of the totd spin of the proton. The origin of the remaining spin is the key question in current hadronic physics and also the major driving forces for the current and future experiments, such as RHIC and CEBAF in US, JPARC in Japan, COMPASS at CERN in Europe, FAIR at GSI in Germany. Among these studies, the transverse-spin physics develops actively and rapidly in the last few years. Recent studies reveal that transverse-spin physics is closely related to many fundamental properties of the QCD dynamics such as the factorization, the non-trivial universality of the parton distribution and fragmentation functions. It was very timely to bring together the theorists and experimentalists in this field at this workshop to review and discuss the latest developments and future perspective in hadronic spin physics. This workshop was very success iu many aspects. First of all, it attracted almost every expert working in this field. We had more than eighty participants in total, among them 27 came from the US institutes, 13 from Europe, 3 from Korea, and 2 from Japan. The rest participants came from local institutes in China. Second, we arranged plenty physics presentations, and the program covers all recent progresses made in the last few years. In total, we had 47 physics presentations, and two round table discussions. The discussion sessions were especially very useful and very much appreciated by all participants. In addition, we also scheduled plenty time for discussion in each presentation, and the living discussions impressed and benefited all participants.

  3. Formability Studies on Transverse Tailor Welded Blanks

    International Nuclear Information System (INIS)

    Bhaskar, V. Vijay; Narasimhan, K.

    2005-01-01

    Tailor Welded Blanks (TWB) technology is one of the several approaches that have been used to reduce the weight of the automobile body. TWBs are made up of two or more blanks having different/same properties (geometry, material etc.) prior to forming. The formability of these blanks depends on material and geometric parameters like strength ratio and thickness ratio. The study of these blanks can be classified on the basis of the weld orientation chosen viz. transverse weld or longitudinal weld with respect to the major straining direction.This paper studies the formability issues related to transverse TWB by FE simulation. The formability is assessed by analyzing tensile and Limit Dome Height (LDH) tests. The weld region is assumed to be a line in all the simulations. While modeling the tensile test, ultimate tensile strength (UTS) and elongation are monitored, and in LDH testing, pole height and maximum load (in near plane strain condition) are monitored. LDH testing shows that as thickness ratio increases, the load bearing capacity and the pole height decreases. There is a contribution from both the thicker and the thinner blank to the overall deforming volume. Failure location analysis shows that there is an abrupt change in the location of the failure from punch nose region to weld line region as the thickness ratio reaches a critical magnitude (1.08).The study of material properties shows that as the yield strength ratio (S ratio) and strain hardening exponent ratio (N ratio) between the blanks increases, the maximum load which the blank can sustain without failure (UTS) increases. This becomes constant and comparable to that of single sheet at higher N and S ratios

  4. Formability Studies on Transverse Tailor Welded Blanks

    Science.gov (United States)

    Bhaskar, V. Vijay; Narasimhan, K.

    2005-08-01

    Tailor Welded Blanks (TWB) technology is one of the several approaches that have been used to reduce the weight of the automobile body. TWBs are made up of two or more blanks having different/same properties (geometry, material etc.) prior to forming. The formability of these blanks depends on material and geometric parameters like strength ratio and thickness ratio. The study of these blanks can be classified on the basis of the weld orientation chosen viz. transverse weld or longitudinal weld with respect to the major straining direction. This paper studies the formability issues related to transverse TWB by FE simulation. The formability is assessed by analyzing tensile and Limit Dome Height (LDH) tests. The weld region is assumed to be a line in all the simulations. While modeling the tensile test, ultimate tensile strength (UTS) and elongation are monitored, and in LDH testing, pole height and maximum load (in near plane strain condition) are monitored. LDH testing shows that as thickness ratio increases, the load bearing capacity and the pole height decreases. There is a contribution from both the thicker and the thinner blank to the overall deforming volume. Failure location analysis shows that there is an abrupt change in the location of the failure from punch nose region to weld line region as the thickness ratio reaches a critical magnitude (1.08). The study of material properties shows that as the yield strength ratio (S ratio) and strain hardening exponent ratio (N ratio) between the blanks increases, the maximum load which the blank can sustain without failure (UTS) increases. This becomes constant and comparable to that of single sheet at higher N and S ratios.

  5. Control of Supercavitating Vehicles using Transverse Jets

    Science.gov (United States)

    2016-03-15

    currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (00-MM-YYYY) 12. REPORT TYPE 3. DATES COVERED...From - To) 03/15/2016 Final Technical Report 15-06-2013 to 15-12-2015 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Control of Supercavitating Vehicles...frequency and expelled fluid slug stroke ratio. Thrust decreased with increasing crossflow velocity, and this decrease was linear for the range of

  6. 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).

  7. 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.

  8. Velocity evolution of galaxy clustering

    Energy Technology Data Exchange (ETDEWEB)

    Saslaw, W.C.; Aarseth, S.J.

    1982-02-15

    We have examined the changing velocity distribution of galaxies as they cluster in computer models of the expanding universe. The models are 4000-body numerical simulations of galaxies with a large range of masses interacting gravitationally. Clustering in velocity space is measured by calculating the residual peculiar velocities around the Hubble expansion. These form ''Hubble streaks as clustering progresses. We distinguish isolated field galaxies from clustered galaxies. In contrast to the usual belief, the velocity dispersion of the most extreme field galaxies does not decrease adiabatically. Rather, it is dominated by the perturbations of distant large clusters as they form and it decreases much more slowly than the inverse expansion length scale, R/sup -1/. The velocity dispersion of extreme field galaxies is a good cosmological indicator of ..cap omega.. = rho/rho/sub crit/. Preliminary comparison of several simulations with observtions shows that our universe agrees better with low density models, ..cap omega..< or =0.1. The velocity dispersion of cluster centers of mass is a good cosmological marker as well. We also suggest another new method for estimating ..cap omega.., based on the history of extreme field galaxies.

  9. Influence of local mechanical properties of high strength steel from large size forged ingot on ultrasonic wave velocities

    Science.gov (United States)

    Dupont-Marillia, Frederic; Jahazi, Mohamad; Lafreniere, Serge; Belanger, Pierre

    2017-02-01

    In the metallurgical industry, ultrasonic inspection is routinely used for the detection of defects. For the non-destructive inspection of small high strength steel parts, the material can be considered isotropic. However, when the size of the parts under inspection is large, the isotropic material hypothesis does not necessarily hold. The aim of this study is to investigate the effect of the variation in mechanical properties such as grain size, Young's modulus, Poissons ratio, chemical composition on longitudinal and transversal ultrasonic wave velocities. A 2 cm thick slice cut from a 40-ton bainitic steel ingot that was forged and heat treated was divided into 875 parallelepiped samples of 2x4x7 cm3. A metallurgical study has been performed to identify the phase and measure the grain size. Ultrasonic velocity measurements at 2.25 MHz for longitudinal and transversal waves were performed. The original location of the parallelepiped samples in the large forged ingot, and the measured velocities were used to produce an ultrasonic velocity map. Using a local isotropy assumption as well as the local density of the parallelepiped samples calculated from the chemical composition of the ingot provided by a previously published study, Youngs modulus and Poissons ratio were calculated from the longitudinal and transversal wave velocities. Micro-tensile test was used to validate Youngs modulus obtained by the ultrasonic wave velocity and an excellent agreement was observed.

  10. Transverse myelitis associated with Zika virus infection: a Case Report

    OpenAIRE

    Beattriz Vaz Pereira Casagrande; Danielle Oliveira de Sousa; Adriana Kamilly Leitão Pitman Machado; Carolina Ribeiro Mainardi; Carolina Barros Kahwage

    2018-01-01

    Title: Transverse myelitis associated with Zika virus infection: a Case Report.: The zika virus belongs to the family flaviviridae, and is transmitted by the arthropod Aedes aegypt. Its major importance is related to the several debilitating neurological manifestations associated with it, such as transverse myelitis. Case: The authors report a case of transverse myelitis in a patient with a previous diagnosis of Zika virus infection. After the image exams and serology, the diagnosis was ...

  11. Transverse mode coupling instability for leptons in the CERN SPS

    Energy Technology Data Exchange (ETDEWEB)

    Linnecar, T.; Shaposhnikova, E.N. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    The intensity of leptons accelerated in the SPS machine is limited by a vertical transverse instability. The results of measurements of the thresholds for this transverse instability are compared with theoretical predictions for different broad band impedance models of the SPS. The threshold intensities found for the transverse instability and the position of the losses in the cycle enable the parameters of the broadband resonant impedance to be specified. (author)

  12. Transverse colon cancer with Krukenberg tumor : A case report

    OpenAIRE

    東門, 敦子; 松原, 洋孝; 下地, 英明; 伊佐, 勉; 濱安, 俊吾; 仲地, 厚; 宮里, 浩; 白石, 祐之; 武藤, 良弘; Tomon, Atsuko; Matsubara, Hirotaka; Shimoji, Hideaki; Isa, Tsutomu; Nakachi, Atsushi; Miyazato, Hiroshi

    1999-01-01

    A case of Krukenberg tumor in a 30-year-old woman with transverse colon cancer is reported herein. The patient was found to have bilateral ovarian tumors and abnormal elevation of serum CEA at a community hospital. Subsequently, she was referred to the University Hospital for further work. Diagnostic examinations including US, CT and colonoscopy demonstrated transverse colon cancer and bilateral ovarian tumors. Exploratory laparotomy showed the growth of transverse colon cancer over the perit...

  13. Curative resection of transverse colon cancer via minilaparotomy.

    Science.gov (United States)

    Ishida, Hideyuki; Ishiguro, Tohru; Ishibashi, Keiichiro; Ohsawa, Tomonori; Okada, Norimichi; Kumamoto, Kensuke; Haga, Norihiro

    2011-01-01

    Minilaparotomy has been reported to be a minimally invasive alternative to laparoscopically assisted surgery. We retrospectively evaluated the usefulness of minilaparotomy for the resection of transverse colon cancer, which has generally been considered difficult to resect laparoscopically. Patients for whom curative resection was attempted for transverse colon cancer (n = 21) or sigmoid colon cancer (n = 81) via minilaparotomy (skin incision, transverse colon cancer as well as those with sigmoid colon cancer.

  14. Pediatria ambiental: um tema emergente

    OpenAIRE

    Valenzuela,Patricia M.; Matus,M. Soledad; Araya,Gabriela I.; Paris,Enrique

    2011-01-01

    OBJETIVO: Revisar os artigos mais relevantes sobre a pediatria ambiental, seus efeitos potenciais para a saúde e, especialmente, seus avanços na prevenção. FONTES DOS DADOS: Foi realizada uma pesquisa utilizando as bases de dados MEDLINE/PubMed e SciELO. Foram revisados artigos de 1990 a 2010, além de capítulos de livros relacionados à pediatria ambiental. SÍNTESE DOS DADOS: Há uma variedade significativa de fatores que tornam as crianças altamente vulneráveis à exposição a riscos ambientais,...

  15. Ambient cosmology and spacetime singularities

    CERN Document Server

    Antoniadis, Ignatios

    2015-01-01

    We present a new approach to the issues of spacetime singularities and cosmic censorship in general relativity. This is based on the idea that standard 4-dimensional spacetime is the conformal infinity of an ambient metric for the 5-dimensional Einstein equations with fluid sources. We then find that the existence of spacetime singularities in four dimensions is constrained by asymptotic properties of the ambient 5-metric, while the non-degeneracy of the latter crucially depends on cosmic censorship holding on the boundary.

  16. Ambient cosmology and spacetime singularities

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, Ignatios [Bern University, Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern (Switzerland); Ecole Polytechnique, Palaiseau (France); Cotsakis, Spiros [CERN, Theory Division, Department of Physics, Geneva 23 (Switzerland); National Technical University, School of Applied Mathematics and Physical Sciences, Athens (Greece)

    2015-01-01

    We present a new approach to the issues of spacetime singularities and cosmic censorship in general relativity. This is based on the idea that standard 4-dimensional spacetime is the conformal infinity of an ambient metric for the 5-dimensional Einstein equations with fluid sources. We then find that the existence of spacetime singularities in four dimensions is constrained by asymptotic properties of the ambient 5-metric, while the non-degeneracy of the latter crucially depends on cosmic censorship holding on the boundary. (orig.)

  17. Using second-sound shock waves to probe the intrinsic critical velocity of liquid helium II

    Science.gov (United States)

    Turner, T. N.

    1983-01-01

    A critical velocity truly intrinsic to liquid helium II is experimentally sought in the bulk fluid far from the apparatus walls. Termed the 'fundamental critical velocity,' it necessarily is caused by mutual interactions which operate between the two fluid components and which are activated at large relative velocities. It is argued that flow induced by second-sound shock waves provides the ideal means by which to activate and isolate the fundamental critical velocity from other extraneous fluid-wall interactions. Experimentally it is found that large-amplitude second-sound shock waves initiate a breakdown in the superfluidity of helium II, which is dramatically manifested as a limit to the maximum attainable shock strength. This breakdown is shown to be caused by a fundamental critical velocity. Secondary effects include boiling for ambient pressures near the saturated vapor pressure or the formation of helium I boundary layers at higher ambient pressures. When compared to the intrinsic critical velocity discovered in highly restricted geometries, the shock-induced critical velocity displays a similar temperature dependence and is the same order of magnitude.

  18. Investigation of ambient seismic noise using seismic interferometry in western Montana

    Science.gov (United States)

    Krzywosz, Natalia

    Passive seismic interferometry is a process by which ambient noise data recorded at different seismic stations can be cross-correlated to estimate Green's functions. In the past, both surface waves and body waves have successfully been extracted by cross-correlation of ambient noise data on both regional and global scales. In this study, I have generated Matlab code to simulate an application of seismic interferometry on a synthetic model with pre-defined layers and p-wave velocities. For areas with known velocity models, the Matlab code produced in this study can be used to generate synthetic seismograms, and model the effects of cross-correlation on receiver responses. In order to develop a general understanding of the ambient noise wavefield in western Montana, a spectral analysis program was developed in Matlab. This program is used to process ambient noise data from the Transportable Array (TA) Seismographic Network, and to generate its power spectral density plots and probability density functions. The detailed spectral analysis provides some insight to the ambient noise sources, and their energy distribution throughout western Montana. In addition, an attempt was made to preprocess ambient noise data from the TA array in Matlab for later use. Although preprocessing of the data was successful, limitations in computing power and time, allowed for temporal stacking of only one month of data. The one month period was not long enough to produce Green's functions which contain coherent body waves.

  19. Finite element modelling of aluminum alloy 2024-T3 under transverse impact loading

    Science.gov (United States)

    Abdullah, Ahmad Sufian; Kuntjoro, Wahyu; Yamin, A. F. M.

    2017-12-01

    Fiber metal laminate named GLARE is a new aerospace material which has great potential to be widely used in future lightweight aircraft. It consists of aluminum alloy 2024-T3 and glass-fiber reinforced laminate. In order to produce reliable finite element model of impact response or crashworthiness of structure made of GLARE, one can initially model and validate the finite element model of the impact response of its constituents separately. The objective of this study was to develop a reliable finite element model of aluminum alloy 2024-T3 under low velocity transverse impact loading using commercial software ABAQUS. Johnson-Cook plasticity and damage models were used to predict the alloy's material properties and impact behavior. The results of the finite element analysis were compared to the experiment that has similar material and impact conditions. Results showed good correlations in terms of impact forces, deformation and failure progressions which concluded that the finite element model of 2024-T3 aluminum alloy under low velocity transverse impact condition using Johnson-Cook plastic and damage models was reliable.

  20. Modeling Transversely Isotropic, Viscoelastic, Incompressible Tissue-like Materials with Application in Ultrasound Shear Wave Elastography

    Science.gov (United States)

    Qiang, Bo; Brigham, John C.; Aristizabal, Sara; Greenleaf, James F.; Zhang, Xiaoming; Urban, Matthew W.

    2015-01-01

    In this paper, we propose a method to model the shear wave propagation in transversely isotropic, viscoelastic and incompressible media. The targeted application is ultrasound-based shear wave elastography for viscoelasticity measurements in anisotropic tissues such as the kidney and skeletal muscles. The proposed model predicts that if the viscoelastic parameters both across and along fiber directions can be characterized as a Voigt material, then the spatial phase velocity at any angle is also governed by a Voigt material model. Further, with the aid of Taylor expansions, it is shown that the spatial group velocity at any angle is close to a Voigt type for weakly attenuative materials within a certain bandwidth. The model is implemented in a finite element code by a time domain explicit integration scheme and shear wave simulations are conducted. The results of the simulations are analyzed to extract the shear wave elasticity and viscosity for both the spatial phase and group velocities. The estimated values match well with theoretical predictions. The proposed theory is further verified by an ex vivo tissue experiment measured in a porcine skeletal muscle by an ultrasound shear wave elastography method. The applicability of the Taylor expansion to analyze the spatial velocities is also discussed. We demonstrate that the approximations from the Taylor expansions are subject to errors when the viscosities across or along the fiber directions are large or the maximum frequency considered is beyond the bandwidth defined by radii of convergence of the Taylor expansions. PMID:25591921

  1. Transverse Kelvin-Helmholtz instability with parallel electron dynamics and Coulomb collisions

    International Nuclear Information System (INIS)

    Satyanarayana, P.; Lee, Y.C.; Huba, J.D.

    1987-01-01

    Electron parallel dynamics and Coulomb collisions are included in the analysis of the transverse Kelvin-Helmholtz instability. The electrons are treated kinetically while the ions are treated in the fluid limit. It is shown that in the collisionless case, for an imhomogeneous velocity profile V(x) = V 0 tanh (x/L) the Kelvin-Helmholtz instability is stable for k/sub z//k/sub y/>(V 0 /Lω/sub l//sub h/)K/sub y/L [2(1-k/sub y/ 2 L 2 )]/sup 1/2/ in the limit ω-k/sub y/V 0 >>k/sub z/v/sub e/. Here V 0 is the flow velocity, L is the scale length of the velocity shear layer, k/sub z/ and k/sub y/ are the parallel and perpendicular wave numbers, respectively, ω/sub l//sub h/ = (Ω/sub e/Ω/sub i/)/sup 1/2/, and v/sub e/ is the electron thermal velocity. The stabilization of the mode is shown to be caused by the compressional energy given to the electrons parallel to B. In the collisional limit, Coulomb collisions are shown to increase the unstable k/sub z/ domain becasue they inhibit the electron motion parallel to B. Applications to the high-latitude ionosphere are discussed. Copyright American Geophysical Union 1987

  2. Modeling transversely isotropic, viscoelastic, incompressible tissue-like materials with application in ultrasound shear wave elastography

    International Nuclear Information System (INIS)

    Qiang, Bo; Aristizabal, Sara; Greenleaf, James F; Zhang, Xiaoming; Urban, Matthew W; Brigham, John C

    2015-01-01

    In this paper, we propose a method to model the shear wave propagation in transversely isotropic, viscoelastic and incompressible media. The targeted application is ultrasound-based shear wave elastography for viscoelasticity measurements in anisotropic tissues such as the kidney and skeletal muscles. The proposed model predicts that if the viscoelastic parameters both across and along fiber directions can be characterized as a Voigt material, then the spatial phase velocity at any angle is also governed by a Voigt material model. Further, with the aid of Taylor expansions, it is shown that the spatial group velocity at any angle is close to a Voigt type for weakly attenuative materials within a certain bandwidth. The model is implemented in a finite element code by a time domain explicit integration scheme and shear wave simulations are conducted. The results of the simulations are analyzed to extract the shear wave elasticity and viscosity for both the spatial phase and group velocities. The estimated values match well with theoretical predictions. The proposed theory is further verified by an ex vivo tissue experiment measured in a porcine skeletal muscle by an ultrasound shear wave elastography method. The applicability of the Taylor expansion to analyze the spatial velocities is also discussed. We demonstrate that the approximations from the Taylor expansions are subject to errors when the viscosities across or along the fiber directions are large or the maximum frequency considered is beyond the bandwidth defined by radii of convergence of the Taylor expansions. (paper)

  3. La crisis del medio ambiente

    Directory of Open Access Journals (Sweden)

    Juan Carlos Quintero Vélez

    2013-07-01

    Full Text Available Este artículo, introducción al tema del medio ambiente, pretende proporcionar conceptos básicos para analizar y dimensionar el impacto que genera el hombre sobre los sistemas que soportan la vida. Para entender estos problemas, es indispensable partir de un análisis básico de la relación entre el hombre actual, su medio ambiente, sus necesidades y sus actividades. El autor revisa los antecedentes, las causas y las consecuencias de la crisis ambiental internacional, e intenta dar explicación a la problemática nacionalen este campo, y establecer los puntos más críticos en Colombia. Finalmente, con base en los parámetros establecidos por el gobierno, se presenta el concepto de“desarrollo sostenible" como modelo que interrelaciona los procesos económicos, sociales y tecnológicos con el medio ambiente.

  4. Shape analysis for Mobile Ambients

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2000-01-01

    The ambient calculus is a calculus of computation that allows active processes to move between sites. We present an analysis inspired by state-of-the-art pointer analyses that safety and accurately predicts which processes may turn up at what sites during the execution of a composite system...

  5. Abstract Interpretation of Mobile Ambients

    DEFF Research Database (Denmark)

    Hansen, René Rydhof; Jensen, J. G.; Nielson, Flemming

    1999-01-01

    We demonstrate that abstract interpretation is useful for analysing calculi of computation such as the ambient calculus (which is based on the p-calculus); more importantly, we show that the entire development can be expressed in a constraint-based formalism that is becoming exceedingly popular...

  6. Shape analysis for mobile ambients

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2001-01-01

    The ambient calculus is a calculus of computation that allows active processes to move between sites. We present an analysis inspired by state-of-the-art pointer analyses that safely and accurately predicts which processes may turn up at what sites during the execution of a composite system...

  7. Nanomaterials vs Ambient Ultrafine Particles

    DEFF Research Database (Denmark)

    Stone, Vicki; Miller, Mark R.; Clift, Martin J. D.

    2017-01-01

    BACKGROUND: A rich body of literature exists that has demonstrated adverse human health effects following exposure to ambient air particulate matter (PM), and there is strong support for an important role of ultrafine (nanosized) particles. At present, relatively few human health or epidemiology ...

  8. [On ambient experience medical products].

    Science.gov (United States)

    Su, Jun

    2010-05-01

    Through the analysis on ambient experience medical products from Philips corporation, the article discusses the development trend of medical products, management strategy and design thinking as focusing on advantage industry, focusing on user experience, system integration of resources and opening and diverse design thinking.

  9. Computer vision for ambient intelligence

    NARCIS (Netherlands)

    Salah, A.A.; Gevers, T.; Sebe, N.; Vinciarelli, A.

    2011-01-01

    A natural way of conceptualizing ambient intelligence is by picturing an active environment with access to perceptual input, not via eyes and ears, but by their technological counterparts. Computer vision is an essential part of building context-aware environments that adapt and anticipate their

  10. Shapiro steps for skyrmion motion on a washboard potential with longitudinal and transverse ac drives

    Science.gov (United States)

    Reichhardt, C.; Reichhardt, C. J. Olson

    2015-12-01

    We numerically study the behavior of two-dimensional skyrmions in the presence of a quasi-one-dimensional sinusoidal substrate under the influence of externally applied dc and ac drives. In the overdamped limit, when both dc and ac drives are aligned in the longitudinal direction parallel to the direction of the substrate modulation, the velocity-force curves exhibit classic Shapiro step features when the frequency of the ac drive matches the washboard frequency that is dynamically generated by the motion of the skyrmions over the substrate, similar to previous observations in superconducting vortex systems. In the case of skyrmions, the additional contribution to the skyrmion motion from a nondissipative Magnus force shifts the location of the locking steps to higher dc drives, and we find that the skyrmions move at an angle with respect to the direction of the dc drive. For a longitudinal dc drive and a perpendicular or transverse ac drive, the overdamped system exhibits no Shapiro steps; however, when a finite Magnus force is present, we find pronounced transverse Shapiro steps along with complex two-dimensional periodic orbits of the skyrmions in the phase-locked regimes. Both the longitudinal and transverse ac drives produce locking steps whose widths oscillate with increasing ac drive amplitude. We examine the role of collective skyrmion interactions and find that additional fractional locking steps occur for both longitudinal and transverse ac drives. At higher skyrmion densities, the system undergoes a series of dynamical order-disorder transitions, with the skyrmions forming a moving solid on the phase locking steps and a fluctuating dynamical liquid in regimes between the steps.

  11. TWITCH PARAMETERS IN TRANSVERSAL AND LONGITUDINAL BICEPS BRACHII RESPONSE

    Directory of Open Access Journals (Sweden)

    Boštjan Šimunič

    2010-01-01

    Full Text Available Assessment of the contractile properties of skeletal muscles is continuing to be an important issue and a difficult task methodologically. Longitudinal direction of skeletal muscle contraction blurs intrinsic muscle belly contractile properties with many factors. This study evaluates and explains contractile properties such as: delay time (Td, contraction time (Tc, half relaxation time (Tr and maximal amplitude (Dm extracted from twitch transversal response and compare them with torque response. In fifteen healthy males (age 23.7 ± 3.4 years isometric twitch transversal and torque responses were simultaneously recorded during graded electrically elicited contractions in the biceps brachii muscle. The amplitude of electrical stimulation was increased in 5 mA steps from a threshold up to a maximal response. The muscles’ belly transversal response was measured by a high precision mechanical displacement sensor while elbow joint torque was calculated from force readings. Results indicate a parabolic relation between the transversal displacement and the torque Dm. A significantly shorter Tc was found in transversal response without being correlated to torque Tc (r = -0.12; > 0.05. A significant correlation was found between torque Tc and the time occurrence of the second peak in the transversal response (r = 0.83; < 0.001. Electrical stimulation amplitude dependant variation of the Tc was notably different in transversal than in torque response. Td was similar at submaximal and maximal responses but larger in transversal at just above threshold contractions. Tr has a similar linear trend in both responses, however, the magnitude and the slope are much larger in the transversal response. We could conclude that different mechanisms affect longitudinal and transversal twitch skeletal muscle deformations. Contractile properties extracted from the transversal response enable alternative insights into skeletal muscle contraction mechanics.

  12. Derecho Ambiental Ecuatoriano, quo vadis?

    Directory of Open Access Journals (Sweden)

    Mónica Ribadeneira Sarmiento

    2016-12-01

    Full Text Available El derecho ambiental, reconocido como tal, es una de las ramas más modernas del derecho y el estudio de su historia y evolución divide a los autores. Sobre la base de una revisión histórica, el artículo expone el concepto y los principios del derecho ambiental y concluye con un análisis del texto constitucional y prueba como en la práctica se debilitan varios principios de esta rama especializada que son resultados precisamente de la evolución histórica que se presenta en el artículo en su primera parte; se incluye entre las conclusiones una alerta sobre las consecuencias de este paulatino debilitamiento. El objetivo principal de este artículo es presentar la evolución del derecho ambiental para contribuir con su divulgación y evidenciar que la importancia de mantener técnica en su definición para evitar su debilitamiento. Durante su elaboración se trabajó principalmente con fuentes documentales, revisión bibliográfica de investigaciones y artículos de tratadistas reconocidos. El artículo contiene: (i introducción, (ii evolución histórica global y latinoamericana, (iii concepto y principios del derecho ambiental, (iv breve análisis de las normas ambientales en la Constitución del Ecuador, enfatizando en aquellas relativas a los derechos de la naturaleza y el caso de los transgénicos, también llamados organismos genéticamente modificados, y a modo de conclusión se expone sobre la perspectiva del desarrollo futuro del derecho ambiental en Ecuador.

  13. 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.

  14. Development of Hydroxyl Tagging Velocimetry for Low Velocity Flows

    Science.gov (United States)

    Andre, Matthieu A.; Bardet, Philippe M.; Burns, Ross A.; Danehy, Paul M.

    2016-01-01

    Hydroxyl tagging velocimetry (HTV) is a molecular tagging technique that relies on the photo-dissociation of water vapor into OH radicals and their subsequent tracking using laser induced fluorescence. Velocities are then obtained from time-of-flight calculations. At ambient temperature in air, the OH species lifetime is relatively short (PIV) measurements recorded in identical conditions. Single shot and averaged velocity profiles are obtained in an air jet at room temperature. By modestly raising the temperature (100-200 degC) the OH production increases, resulting in an improvement of the signal-to-noise ratio (SNR). Use of nitrogen - a non-reactive gas with minimal collisional quenching - extends the OH species lifetime (to over 500 µs), which allows probing of slower flows or, alternately, increases the measurement precision at the expense of spatial resolution. Instantaneous velocity profiles are resolved in a 100degC nitrogen jet (maximum jet-center velocity of 6.5 m/s) with an uncertainty down to 0.10 m/s (1.5%) at 68% confidence level. MTV measurements are compared with particle image velocimetry and show agreement within 2%.

  15. Improved accuracy in the estimation of blood velocity vectors using matched filtering

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Gori, P.

    2000-01-01

    The blood velocity can be estimated by finding the shift in position of the blood scatterers between subsequent ultrasonic pulse emissions through cross-correlation of the received RF signals. Usually only the velocity component along the beam direction is found. It was shown in a previous paper...... that the complete velocity vector can be found, if the received signals are focused along lines parallel to the direction of the blood flow. A fairly broad beam is emitted in the approach, and this gives rise to a widening in the profiles of the estimated velocity. To reduce this effect, a focused ultrasound...... emission is used in this study to decrease the size of the beam. The transverse beam lines are then constructed by using filters matched to the response of the individual channels. The filters matched to the points on the focusing lines are obtained by considering the field response of the employed array...

  16. Relating inclusive and exclusive meson photoproduction at large transverse momentum

    International Nuclear Information System (INIS)

    Scott, D.M.

    1975-01-01

    Inclusive and exclusive meson photoproduction at large transverse momentum are related by a local application of the correspondence principle of Bjorken and Kogut. The recent predictions for the inclusive process by Escobar are thus compared with wide angle exclusive data. The inclusive photoproduction of (rho 0 +ω) at large transverse momentum is discussed. (Auth.)

  17. On the number of isomorphism classes of transversals

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 123; Issue 3 ... Group torsion; right loop; normalized right transversal. Abstract. In this paper we prove that there does not exist a subgroup of a finite group such that the number of isomorphism classes of normalized right transversals of in is four.

  18. Transverse momentum spectra of the produced hadrons at SPS ...

    Indian Academy of Sciences (India)

    2014-04-30

    Apr 30, 2014 ... The successive collisions in the nuclear reaction lead to gain in transverse momentum, as the nucleons propagate in the nucleus following a random walk pattern. The average transverse rapidity shift per collision is determined from the nucleon–nucleus collision data. Using this information, we obtain ...

  19. Transverse lie in labor: A study from Kaduna, Northern Nigeria ...

    African Journals Online (AJOL)

    Results: During the period there were 16633 deliveries and 30 women with transversely lying fetuses, giving an incidence of 1 in 554 deliveries. Forty percent of the cases were neglected transverse lies. The para 4 and above group had the highest incidence of 2.69/1000. Northern minorities ethnic group had the highest ...

  20. Landforms along transverse faults parallel to axial zone of folded ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 1. Landforms along transverse faults parallel to axial zone of folded mountain front, north-eastern Kumaun Sub-Himalaya, India. Khayingshing ... Keywords. Himalayan Frontal Thrust; outer Kumaun Himalaya; transverse structure; folded mountain front.

  1. The influence of gluteus maximus on transverse plane tibial rotation

    NARCIS (Netherlands)

    Preece, S.J.; Graham-Smith, P.; Nester, C.J.; Howard, D.; Hermens, Hermanus J.; Herrington, L.; Bowker, P.

    There is a common clinical belief that transverse plane tibial rotation is controlled by the rearfoot. Although distal structures may influence the motion of the tibia, transverse plane tibial rotation could be determined by the proximal hip musculature. Cadaver studies have identified gluteus

  2. Some anatomical and morphometric observations in the transverse ...

    African Journals Online (AJOL)

    A hundred and two atlases obtained from the Osteology Department of National Museums of Kenya were observed for presence, shape and variations of the transverse foramen. Accessory transverse foramina were noted, as well as missing foramina. Anteroposterior and mediolateral diameters of the foramina were taken ...

  3. Operational characteristics and power scaling of a transverse flow ...

    Indian Academy of Sciences (India)

    Abstract. Transverse flow transversely excited (TFTE) CO2 lasers are easily scalable to multi- kilowatt level. The laser power can be scaled up by increasing the volumetric gas flow and discharge volume. It was observed in a TFTE CW CO2 laser having single row of pins as an anode and tubular cathode that the laser ...

  4. Transverse oscillation vector flow imaging for transthoracic echocardiography

    DEFF Research Database (Denmark)

    Bradway, David; Lindskov Hansen, Kristoffer; Nielsen, Michael Bachmann

    2015-01-01

    This work presents the development and first results of in vivo transthoracic cardiac imaging using an implementation of Vector Flow Imaging (VFI) via the Transverse Oscillation (TO) method on a phased-array transducer. Optimal selection of the lateral wavelength of the transversely-oscillating r...

  5. Measurement of the transverse emittance for the NSC Pelletron

    International Nuclear Information System (INIS)

    Rodriques, G.; Mandal, A.; Chopra, S.; Joshi, R.; Datta, S.K.; Roy, A.

    1998-01-01

    The knowledge of the emittance (transverse and longitudinal) of the NSC pelletron is essential for matching the acceptance of the LINAC which is to be installed to augment the pelletron beam energies. The transverse emittance of NSC pelletron has been measured by employing a focussing element and a down-stream beam profile monitor

  6. Semi-inclusive deep inelastic scattering at small transverse momentum

    NARCIS (Netherlands)

    Bacchetta, A.; Diehl, M.; Goeke, K.; Metz, A.; Mulders, P.J.G.; Schlegel, M.

    2007-01-01

    We study the cross section for one-particle inclusive deep inelastic scattering off the nucleon for low transverse momentum of the detected hadron. We decompose the cross section in terms of structure functions and calculate them at tree level in terms of transverse-momentum-dependent parton

  7. Joint transverse momentum and threshold resummation beyond NLL

    NARCIS (Netherlands)

    Lustermans, G.; Waalewijn, W.J.; Zeune, L.

    2016-01-01

    To describe the transverse momentum spectrum of heavy color-singlet production, the joint resummation of threshold and transverse momentum logarithms is investigated. We obtain factorization theorems for various kinematic regimes valid to all orders in the strong coupling, using Soft-Collinear

  8. Contact mechanics and friction for transversely isotropic viscoelastic materials

    NARCIS (Netherlands)

    Mokhtari, Milad; Schipper, Dirk J.; Vleugels, N.; Noordermeer, Jacobus W.M.; Yoshimoto, S.; Hashimoto, H.

    2015-01-01

    Transversely isotropic materials are an unique group of materials whose properties are the same along two of the principal axes of a Cartesian coordinate system. Various natural and artificial materials behave effectively as transversely isotropic elastic solids. Several materials can be classified

  9. Fermions in light front transverse lattice quantum chromodynamics

    Indian Academy of Sciences (India)

    We briefly describe motivations for studying transverse lattice QCD. Presence of constraint equation for fermion field on the light front allows different methods to put fermions on a transverse lattice. We summarize our numerical investigation of two approaches using (a) forward and backward derivatives and (b) symmetric ...

  10. Waves with negative group velocity. Conditions of their existence in a isotropic medium

    International Nuclear Information System (INIS)

    Makarov, V.P.; Rukhadze, A.A.; Samokhin, A.A.

    2005-01-01

    The analysis of the frequency and spatial dispersions of the dielectric permittivity and magnetic permeability of an isotropic medium are carried out in the (E-vector, B-vector, D-vector) and (E-vector, B-vector, D-vector, H-vector) approaches of electrodynamics. The conditions under which the phase and group velocities of transverse electromagnetic waves have opposite directions are clarified, and the consequences arised are discussed

  11. Transverse mode coupling instability of colliding beams

    Directory of Open Access Journals (Sweden)

    S. White

    2014-04-01

    Full Text Available In high brightness circular colliders, coherent and incoherent beam dynamics are dominated by beam-beam interactions. It is generally assumed that the incoherent tune spread introduced by the beam-beam interactions is sufficiently large to cure any instabilities originating from impedance. However, as the two counterrotating beams interact they can give rise to coherent dipole modes and therefore modify the coherent beam dynamics and stability conditions. In this case, coherent beam-beam effects and impedance cannot be treated independently and their interplay should be taken into account in any realistic attempt to study the beam stability of colliding beams. Due to the complexity of these physics processes, numerical simulations become an important tool for the analysis of this system. Two approaches are proposed in this paper: a fully self-consistent multiparticle tracking including particle-in-cell Poisson solver for the beam-beam interactions and a linearized model taking into account finite bunch length effects. To ensure the validity of the results a detailed benchmarking of these models was performed. It will be shown that under certain conditions coherent beam-beam dipole modes can couple with higher order headtail modes and lead to strong instabilities with characteristics similar to the classical transverse mode coupling instability originating from impedance alone. Possible cures for this instability are explored both for single bunch and multibunch interactions. Simulation results and experimental evidences of the existence of this instability at the LHC will be presented for the specific case of offset collisions.

  12. Transverse stability in multibunch mode for CLIC

    International Nuclear Information System (INIS)

    Guignard, G.

    1993-01-01

    In order to reach the desired luminosity with 250 GeV per beam, multibunch operation (limited to 4 bunches, say) might have to be considered in the CERN linear collider (CLIC). One limitation comes from the coupling of the bunch motion with the long-range transverse wake fields that may induce beam breakup. These wake fields have therefore to be controlled, and means of reducing their effects on the beam are discussed in a companion paper. One possibility consists in detuning the dipole modes in the cells to obtain decoherent contributions and hence reduce the field amplitude at the downstream bunch location. The important question is to know below which value this amplitude must be limited to prevent intolerable beam breakup. In a first attempt at estimating this threshold for CLIC two approaches are considered, i.e. the criterion developed at SLAC and based on the convergence of the multibunch-motion solution, and numerical simulations of two-bunch motion in a focusing lattice

  13. The Superior Transverse Scapular Ligament in Fetuses

    Directory of Open Access Journals (Sweden)

    José Aderval Aragão

    2013-01-01

    Full Text Available Introduction. The superior transverse scapular ligament (STSL links the margins of the suprascapular notch and converts it into a foramen, through which, the suprascapular nerve and, on some rare occasions, the suprascapular vessels pass. This conversion often results from partial or complete ossification of the STSL and may produce compressive symptoms in the suprascapular nerve. Material and Method. Twenty shoulders from human fetuses were dissected without the aid of optical instruments and, using a digital pachymeter of precision 0.01 millimeters, length measurements and thickness measurements were made. The fetal age was from 21 to 33 weeks of gestation, with a mean of 27.6±4.14 weeks. Results. There was no statistically significant difference in STSL length or any difference in the thicknesses at the medial and lateral extremities between the halves of the body (P≥0.05. However, in the left half of the body, the medial extremity of the STSL was significantly thinner than the lateral extremity (P≤0.05. Conclusion. Anatomical and morphometric details about the STSL were described in human fetuses. These findings, in fetuses, may encourage the pursuit of further studies to understand the morphofunctional role and meaning of this small ligament.

  14. Transversity Amplitudes in Hypercharge Exchange Processes

    International Nuclear Information System (INIS)

    Aguilar Benitez de Lugo, M.

    1979-01-01

    ' In this work we present several techniques developed for the extraction of the. Transversity amplitudes governing quasi two-body meson baryon reactions with hypercharge exchange. We review the methods used in processes having a pure spin configuration, as well as the more relevant results obtained with data from K p and Tp interactions at intermediate energies. The predictions of the additive quark model and the ones following from exchange degeneracy and etoxicity are discussed. We present a formalism for amplitude analysis developed for reactions with mixed spin configurations and discuss the methods of parametric estimation of the moduli and phases of the amplitudes, as well as the various tests employed to check the goodness of the fits. The calculation of the generalized joint density matrices is given and we propose a method based on the generalization of the idea of multipole moments, which allows to investigate the structure of the decay angular correlations and establishes the quality of the fits and the validity of the simplifying assumptions currently used in this type of studies. (Author) 43 refs

  15. TRANSVERSE OSCILLATIONS OF SYSTEMS OF CORONAL LOOPS

    International Nuclear Information System (INIS)

    Luna, M.; Oliver, R.; Ballester, J. L.; Terradas, J.

    2009-01-01

    We study the collective kinklike normal modes of a system of several cylindrical loops using the T-matrix theory. Loops that have similar kink frequencies oscillate collectively with a frequency which is slightly different from that of the individual kink mode. On the other hand, if the kink frequency of a loop is different from that of the others, it oscillates individually with its own frequency. Since the individual kink frequency depends on the loop density but not on its radius for typical 1 MK coronal loops, a coupling between kink oscillations of neighboring loops takes place when they have similar densities. The relevance of these results in the interpretation of the oscillations studied by Schrijver and Brown in 2000 and Verwichte et al. in 2004, in which transverse collective loop oscillations seem to be detected, is discussed. In the first case, two loops oscillating in antiphase are observed; interpreting this motion as a collective kink mode suggests that their densities are roughly equal. In the second case, there are almost three groups of tubes that oscillate with similar periods, and therefore their dynamics can be collective, which again seems to indicate that the loops of each group share a similar density. All the other loops seem to oscillate individually and their densities can be different from the rest.

  16. The LHC Transverse Coupled-Bunch Instability

    CERN Document Server

    Mounet, Nicolas; Métral, Elias

    In this thesis, the problem of the transverse coupled-bunch instabilities created by the Large Hadron Collider (LHC) beam-coupling impedance, that can possibly limit the machine operation, is addressed thanks to several new theories and tools. A rather complete vision of the problem is proposed here, going from the calculation of the impedances and wake functions of individual machine elements, to the beam dynamics study. Firstly, new results are obtained in the theory of the beam-coupling impedance for an axisymmetric two-dimensional structure, generalizing Zotter's theories, and a new general theory is derived for the impedance of an infinite flat two-dimensional structure. Then, a new approach has been found to compute the wake functions from such analytically obtained beam-coupling impedances, over-coming limitations that could be met with standard discrete Fourier transform procedures. Those results are then used to obtain an impedance and wake function model of the LHC, based on the (resistive-) wall im...

  17. Classical Ising chain in transverse field

    International Nuclear Information System (INIS)

    Cuccoli, A.; Taiti, A.; Vaia, R.; Verrucchi, P.

    2007-01-01

    The spin 12 Ising chain in transverse field is considered the prototypical system for quantum phase transitions. However, very little is apparently known in literature about its classical counterpart, not to be confused with the standard classical Ising model: while the latter is constructed from classical discrete variables, the model we consider is a chain of classical vectors of modulus 1, interacting via an Ising-like Hamiltonian. When an uniform field is applied perpendicular to the exchange interaction, both the quantum model and its classical counterpart get to be characterized by a critical field separating a ferromagnetically ordered state of minimal energy from a paramagnetic one. The properties of the classical model, and especially the behaviour of the correlation length, are investigated at low temperature around the critical field and compared with those of the quantum model, in order to single out the role played by quantum and classical fluctuations at finite temperature; the possibility to experimentally observe peculiar quantum critical effects in Ising spin chains is discussed

  18. Coupling of transverse and longitudinal waves in piano strings.

    Science.gov (United States)

    Etchenique, Nikki; Collin, Samantha R; Moore, Thomas R

    2015-04-01

    The existence of longitudinal waves in vibrating piano strings has been previously established, as has their importance in producing the characteristic sound of the piano. Modeling of the coupling between the transverse and longitudinal motion of strings indicates that the amplitude of the longitudinal waves are quadratically related to the transverse displacement of the string, however, experimental verification of this relationship is lacking. In the work reported here this relationship is tested by driving the transverse motion of a piano string at only two frequencies, which simplifies the task of unambiguously identifying the constituent signals. The results indicate that the generally accepted relationship between the transverse motion and the longitudinal motion is valid. It is further shown that this dependence on transverse displacement is a good approximation when a string is excited by the impact of the hammer during normal play.

  19. Transverse vibration of pipe conveying fluid made of functionally graded materials using a symplectic method

    International Nuclear Information System (INIS)

    Wang, Zhong-Min; Liu, Yan-Zhuang

    2016-01-01

    Highlights: • We investigate the transverse vibration of FGM pipe conveying fluid. • The FGM pipe conveying fluid can be classified into two cases. • The variations between the frequency and the power law exponent are obtained. • “Case 1” is relatively more reasonable than “case 2”. - Abstract: Problems related to the transverse vibration of pipe conveying fluid made of functionally graded material (FGM) are addressed. Based on inside and outside surface material compositions of the pipe, FGM pipe conveying fluid can be classified into two cases. It is hypothesized that the physical parameters of the material along the direction of the pipe wall thickness change in the simple power law. A differential equation of motion expressed in non-dimensional quantities is derived by using Hamilton's principle for systems of changing mass. Using the assuming modal method, the pipe deflection function is expanded into a series, in which each term is expressed to admissible function multiplied by generalized coordinate. Then, the differential equation of motion is discretized into the two order differential equations expressed in the generalized coordinates. Based on symplectic elastic theory and the introduction of dual system and dual variable, Hamilton's dual equations are derived, and the original problem is reduced to eigenvalue and eigenvector problem in the symplectic space. Finally, a symplectic method is employed to analyze the vibration and stability of FGM pipe conveying fluid. For a clamped–clamped FGM pipe conveying fluid in “case 1” and “case 2”, the dimensionless critical flow velocity for first-mode divergence and the critical coupled-mode flutter flow velocity are obtained, and the variations between the real part and imaginary part of dimensionless complex frequency and fluid velocity, mass ratio and the power law exponent (or graded index, volume fraction) for FGM pipe conveying fluid are analyzed.

  20. Quasi-Rayleigh waves in transversely isotropic half-space with inclined axis of symmetry

    International Nuclear Information System (INIS)

    Yanovskaya, T.B.; Savina, L.S.

    2003-09-01

    A method for determination of characteristics of quasi-Rayleigh (qR) wave in a transversely isotropic homogeneous half-space with inclined axis of symmetry is outlined. The solution is obtained as a superposition of qP, qSV and qSH waves, and surface wave velocity is determined from the boundary conditions at the free surface and at infinity, as in the case of Rayleigh wave in isotropic half-space. Though the theory is simple enough, a numerical procedure for the calculation of surface wave velocity presents some difficulties. The difficulty is conditioned by necessity to calculate complex roots of a non-linear equation, which in turn contains functions determined as roots of nonlinear equations with complex coefficients. Numerical analysis shows that roots of the equation corresponding to the boundary conditions do not exist in the whole domain of azimuths and inclinations of the symmetry axis. The domain of existence of qR wave depends on the ratio of the elastic parameters: for some strongly anisotropic models the wave cannot exist at all. For some angles of inclination qR wave velocities deviate from those calculated on the basis of the perturbation method valid for weak anisotropy, though they have the same tendency of variation with azimuth. The phase of qR wave varies with depth unlike Rayleigh wave in isotropic half-space. Unlike Rayleigh wave in isotropic half-space, qR wave has three components - vertical, radial and transverse. Particle motion in horizontal plane is elliptic. Direction of the major axis of the ellipsis coincide with the direction of propagation only in azimuths 0 deg. (180 deg.) and 90 deg. (270 deg.). (author)

  1. Historical Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Historical Ambient Air Quality Data Inventory contains measured and estimated data on ambient air pollution for use in assessing air quality, assisting in...

  2. EFFECT OF SLIP VELOCITY ON MAGNETIC FLUID LUBRICATION OF ROUGH POROUS RAYLEIGH STEP BEARING

    Directory of Open Access Journals (Sweden)

    Snehal Shukla

    2013-06-01

    Full Text Available This article aims to analyze the performance of a magnetic-fluid-based porous rough step bearing considering slip velocity. The Neuringer-Rosensweig model governs the fluid flow while the velocity slip is modeled by the method of Beavers and Joseph. The bearing surfaces are assumed transversely rough and the transverse surface roughness of the bearing surfaces is characterized by a stochastic random variable with non-zero mean, variance, and skewness. With the usual assumptions of hydrodynamic lubrication, the related stochastically averaged Reynolds’ equation for the fluid pressure is solved with appropriate boundary conditions, which is then used to calculate the load-carrying capacity. It is found that although the bearing suffers owing to transverse surface roughness, the performance of the bearing system can be improved to some extent by the positive effect of magnetization, considering the slip parameter at the minimum; at least in the case of negatively skewed roughness. A comparison of this paper with some established investigations indicates that here, the reduction of load-carrying capacity due to porosity and slip velocity is comparatively less, especially, when negative variance occurs. In augmenting the performance of the bearing system, the step ratio plays a central role, even if the slip parameter is at the minimum.

  3. An upper-mantle S-wave velocity model for Northern Europe from Love and Rayleigh group velocities

    Science.gov (United States)

    Weidle, Christian; Maupin, Valérie

    2008-12-01

    A model of upper-mantle S-wave velocity and transverse anisotropy beneath northwestern Europe is presented, based on regional surface wave observations. Group velocities for both Love and Rayleigh surface waves are measured on waveform data from international and regional data archives (including temporary deployments) and then inverted for group velocity maps, using a method accounting for Fresnel zone sensitivity. The group velocity variations are larger than in global reference maps, and we are able to resolve unprecedented details. We then apply a linear inversion scheme to invert for local 1-D shear wave velocity profiles which are consequently assembled to a 3-D model. By choosing conservative regularization parameters in the 2-D inversion, we ensure the smoothness of the group velocity maps and hence of the resulting 3-D shear wave speed model. To account for the different tectonic regimes in the study region and investigate the sensitivity of the 1-D inversions to inaccuracies in crustal parameters, we analyse inversions with different reference models of increasing complexity (pure 1-D, 3-D crust/1-D mantle and pure 3-D). We find that all inverted models are very consistent at depths below 70 km. At shallower depths, the constraints put by the reference models, primarily Moho depth which we do not invert for, remain the main cause for uncertainty in our inversion. The final 3-D model shows large variations in S-wave velocity of up to +/-12 per cent. We image an intriguing low-velocity anomaly in the depth range 70-150 km that extends from the Iceland plume beneath the North Atlantic and in a more than 400 km wide channel under Southern Scandinavia. Beneath Southern Norway, the negative perturbations are around 10 per cent with respect to ak135, and a shallowing of the anomaly is indicated which could be related to the sustained uplift of Southern Scandinavia in Neogene times. Furthermore, our upper-mantle model reveals good alignment to ancient plate

  4. Observation of Single Isolated Electrons of High Transverse Momentum in Events with Missing Transverse Energy at the CERN pp Collider

    DEFF Research Database (Denmark)

    Banner, M.; Kofoed-Hansen, O.

    1983-01-01

    We report the results of a search for single isolated electrons of high transverse momentum at the CERN collider. Above 15 GeV/c, four events are found having large missing transverse energy along a direction opposite in azimuth to that of the high-pT electron. Both the configuration of the events...

  5. Ambient Art: Creative Information Representation

    Directory of Open Access Journals (Sweden)

    Russell Beale

    2007-01-01

    Full Text Available Ambient art is the aesthetic presentation of information, using artistic techniques to achieve a pleasing image that also contains hidden depths, where exposure to it over time allows a viewer to understand something about the information sources that it represents. This paper reviews the artistic and computational background of ambient systems, and presents two case studies of systems developed by our research team, from their initial design to the experiences of the people encountering them. The first case presents a photo mosaic of images based on the news headlines coupled with a structured picture based on the weather; the second presents stylistic perspectives on activity in a public space. Both are evaluated and demonstrate that different forms of aesthetically pleasing displays can convey information to viewers.

  6. Responsabilidades municipales en materia ambiental

    Directory of Open Access Journals (Sweden)

    Ignacio Pichardo Pagaza

    2009-01-01

    Este trabajo reflexiona en torno a las responsabilidades que la Constitución política impone de manera exclusiva a los municipios y que por su naturaleza tienen efectos directos en el medio ambiente. Se alude aquí a los servicios de agua po ta ble, drenaje, saneamiento, tratamiento de aguas residuales, disposición de residuos sólidos, rastros, panteones y mercados. Ahora son los desafíos ambientales de la autoridad municipal, por lo que deben ser también sus prioridades. Si esos servicios no se atienden oportuna y técnicamente la población sufrirá, se deteriorará gravemente el medio ambiente y disminuirá la calidad de la vida de la comunidad.

  7. Ambient pressure fuel cell system

    Science.gov (United States)

    Wilson, Mahlon S.

    2000-01-01

    An ambient pressure fuel cell system is provided with a fuel cell stack formed from a plurality of fuel cells having membrane/electrode assemblies (MEAs) that are hydrated with liquid water and bipolar plates with anode and cathode sides for distributing hydrogen fuel gas and water to a first side of each one of the MEAs and air with reactant oxygen gas to a second side of each one of the MEAs. A pump supplies liquid water to the fuel cells. A recirculating system may be used to return unused hydrogen fuel gas to the stack. A near-ambient pressure blower blows air through the fuel cell stack in excess of reaction stoichiometric amounts to react with the hydrogen fuel gas.

  8. Tipologia para a contabilidade ambiental

    Directory of Open Access Journals (Sweden)

    Nazlhe Faride Chein Schekaiban

    2007-06-01

    Full Text Available Este artigo revê a visão, as propostas e o desenvolvimento da contabilidade ambiental, refletindo sobre suas implicações, com a finalidade de descobrir e encontrar sua importância e situação. Para se chegar a esse resultado foi preciso realizar uma revisão epistemológica moldada e processo reflexivo de sustentabilidade e da aproximação ao usuário, da percepção da realidade contábil no México e da gerência interna das organizações. As conclusões mostram a contabilidade ambiental no México fora da re-alidade operativa do modelo contábil regional, aumentando a importância de se criar uma cultura capaz de examinar o controle da missão deste tipo de contabilidade.

  9. Ambiente psicologico en las organizaciones

    Directory of Open Access Journals (Sweden)

    Damarcy Cortés Baracaldo

    2002-01-01

    Full Text Available El talento humano en las organizaciones se ha convertido en las ultimas decadas en un recurso que se administra de acuerdo al estilo de liderazgo del jefe, lo que implica una marcada relación hacia la tarea, hacia las relaciones con el personal o una combinación de estas dos, que desencadenan en un ambiente psicológico exclusive en cada organización.

  10. 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

  11. Estrategia para la sustentabilidad ambiental

    Directory of Open Access Journals (Sweden)

    Cecilia Erbiti

    2006-01-01

    Full Text Available En el contexto de los postulados conceptuales y metodológicos de la planificación estratégica y de sustentabilidad ambiental, el objetivo de esta investigación es describir el proceso de formulación del Plan de Ordenamiento Territorial del Municipio de Tandil (POTM y analizar su potencialidad para avanzar hacia la sustentabilidad ambiental del sistema. Los resultados de la misma muestran que el POTM no sólo prioriza principios, objetivos y estrategias que materializan las diferentes manifestaciones de la sustentabilidad (económica, social, ecológica y política, sino que la totalidad del Plan se fundamenta en el concepto de desarrollo sostenible y, con ello, se establecen prioridades de actuación que posibilitarán la gestión ambiental urbana. Si bien el POTM muestra una gran potencialidad para avanzar hacia la sustentabilidad del territorio, la implementación y cumplimiento del mismo constituye un fuerte desafío para las autoridades de aplicación.

  12. The Main Principles of Formation of the Transverse Modes in the Multilayered Waveguides of Surface Acoustic Waves

    Science.gov (United States)

    Sveshnikov, B. V.; Bagdasaryan, A. S.

    2016-07-01

    We develop a self-consistent model allowing one to analyze the properties of the interdigital transducer of the surface acoustic waves as a symmetric five-layered waveguide on a piezoelectric substrate with three possible values of the phase velocity of the acoustic-wave propagation along the longitudinal axis of the system. The transcendental dispersion relation for describing the waves in such a system is derived and the method for its instructive graphic analysis is proposed. The condition under which only the fundamental transverse mode is excited in the waveguide is formulated. The method for calculating the normalized power and the transverse distribution of the field of the continuous-spectrum waves radiated from the considered waveguide is described. It is shown that the characteristic spatial scale of the longitudinal damping of the amplitude of this field at the waveguide center can be a qualitative estimate of the transverse-mode formation length. The efficiency of a new method for suppressing the higher-order transverse waveguide modes is demonstrated.

  13. Body-wave retrieval and imaging from ambient seismic fields with very dense arrays

    Science.gov (United States)

    Nakata, N.; Boué, P.; Beroza, G. C.

    2015-12-01

    Correlation-based analyses of ambient seismic wavefields is a powerful tool for retrieving subsurface information such as stiffness, anisotropy, and heterogeneity at a variety of scales. These analyses can be considered to be data-driven wavefield modeling. Studies of ambient-field tomography have been mostly focused on the surface waves, especially fundamental-mode Rayleigh waves. Although the surface-wave tomography is useful to model 3D velocities, the spatial resolution is limited due to the extended depth sensitivity of the surface wave measurements. Moreover, to represent elastic media, we need at least two stiffness parameters (e.g., shear and bulk moduli). We develop a technique to retrieve P diving waves from the ambient field observed by the dense geophone network (~2500 receivers with 100-m spacing) at Long Beach, California. With two-step filtering, we improve the signal-to-noise ratio of body waves to extract P wave observations that we use for tomography to estimate 3D P-wave velocity structure. The small scale-length heterogeneity of the velocity model follows a power law with ellipsoidal anisotropy. We also discuss possibilities to retrieve reflected waves from the ambient field and show other applications of the body-wave extraction at different locations and scales. Note that reflected waves penetrate deeper than diving waves and have the potential to provide much higher spatial resolution.

  14. The preliminary results: Seismic ambient noise Rayleigh wave tomography around Merapi volcano, central Java, Indonesia

    International Nuclear Information System (INIS)

    Trichandi, Rahmantara; Yudistira, Tedi; Nugraha, Andri Dian; Zulhan, Zulfakriza; Saygin, Erdinc

    2015-01-01

    Ambient noise tomography is relatively a new method for imaging the shallow structure of the Earth subsurface. We presents the application of this method to produce a Rayleigh wave group velocity maps around the Merapi Volcano, Central Java. Rayleigh waves group velocity maps were reconstructed from the cross-correlation of ambient noise recorded by the DOMERAPI array which consists 43 broadband seismometers. In the processing stage, we first filtered the observation data to separatethe noise from the signal that dominated by the strong volcanic activities. Next, we cross-correlate the filtered data and stack to obtain the Green’s function for all possible station pairs. Then we carefully picked the peak of each Green’s function to estimate the dispersion trend and appliedMultiple Filter Technique to obtain the dispersion curve. Inter-station group velocity curvesare inverted to produceRayleigh wave group velocity maps for periods 1 to 10 s. The resulted Rayleigh group velocity maps show the interesting features around the Merapi Volcano which generally agree with the previous studies. Merapi-Lawu Anomaly (MLA) is emerged as a relatively low anomaly in our group velocity maps

  15. The preliminary results: Seismic ambient noise Rayleigh wave tomography around Merapi volcano, central Java, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Trichandi, Rahmantara, E-mail: rachmantara.tri@gmail.com [Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, 40132, Bandung (Indonesia); Yudistira, Tedi; Nugraha, Andri Dian [Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Zulhan, Zulfakriza [Earth Science Graduate Program, Faculty of Earth Science and Technology, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Saygin, Erdinc [Research School of Earth Sciences, The Australian National University, Canberra ACT 0200 (Australia)

    2015-04-24

    Ambient noise tomography is relatively a new method for imaging the shallow structure of the Earth subsurface. We presents the application of this method to produce a Rayleigh wave group velocity maps around the Merapi Volcano, Central Java. Rayleigh waves group velocity maps were reconstructed from the cross-correlation of ambient noise recorded by the DOMERAPI array which consists 43 broadband seismometers. In the processing stage, we first filtered the observation data to separatethe noise from the signal that dominated by the strong volcanic activities. Next, we cross-correlate the filtered data and stack to obtain the Green’s function for all possible station pairs. Then we carefully picked the peak of each Green’s function to estimate the dispersion trend and appliedMultiple Filter Technique to obtain the dispersion curve. Inter-station group velocity curvesare inverted to produceRayleigh wave group velocity maps for periods 1 to 10 s. The resulted Rayleigh group velocity maps show the interesting features around the Merapi Volcano which generally agree with the previous studies. Merapi-Lawu Anomaly (MLA) is emerged as a relatively low anomaly in our group velocity maps.

  16. Transverse Resonant Vibration of Non-Bearing Structures Caused by Wind

    Science.gov (United States)

    Jendzelovsky, Norbert; Antal, Roland

    2017-10-01

    Nowadays, there are increasing use of very thin, subtle and light structures in the field of building constructions. We can find such a structures as part of roofs or design facades. By using these lamellas like, non-bearing structures as a part of architectural design of buildings, it is necessary to consider wind effects on these structures. Subtle structures of this type are prone to vibration in the transverse direction of the wind flow. The fact that the vibration occurs depends on wind parameters (wind velocity, direction of an air flow) and it also depends on the properties of lamella (shape, length, mass, natural frequency, support type). The principal idea of this article is to show susceptibility of lamellae-like structures to transverse resonant vibration caused by the phenomenon called Von Karman effect. Comparison of susceptibility to transverse resonance vibration was analysed on the different shapes of lamellas loaded by different wind speed. Analysis was based on usage of empirically derived equations. Von Karman effect arise from wind flow past an object. Turbulence in the form of vortices are formed at the object and shed into the flowing stream intermittently. The potential problem is that this turbulence can induce vibrations into the lamella itself. In terms of this vibration problem, two frequencies are interesting. Von Karman shedding frequency is the frequency at which the vortices are formed and shed at the object. The vortex-shedding frequency increases with the velocity of the wind flow and decreases with the size of the object. Natural frequency of the object depends on the construction of the lamella itself. Parameters of lamella as a shape, mass, length, elasticity modulus of material and support types are directly involved in the calculation of natural frequency. Worst case scenario in the term of transverse resonant vibration occurs when the natural frequency of lamella is equal to the vortex-shedding frequency. In this case

  17. Variations in Transverse Foramina of Cervical Vertebrae: Morphology & Clinical Importance

    Directory of Open Access Journals (Sweden)

    Vaishakhi Gonsai

    2015-12-01

    Full Text Available Background: The purpose of this study is to investigate variations in transverse foramina in the cervical vertebrae and its morphological and clinical importance. Materials and Method : The variations in the number and size of transverse foramina was studied in total 200 human dried cervical vertebrae, which were taken from the Department of Anatomy, B.J.Medical College, Ahmedabad. All the vertebrae were observed for variation in number and size of transverse foramina. Results: Out of 200 cervical vertebrae, complete double transverse foramina were observed in 40 vertebrae (20%, among them unilateral double foramina were found in 31 vertebrae (15.5% and the bilateral double foramina were found in 9 vertebrae (4.5%. Incomplete double transverse foramina were observed in 22 vertebrae (11%, among them unilateral double foramina were found in 16 vertebrae (8% and bilateral double foramina were observed in 6 vertebrae (3%. Conclusion: Complete unilateral double transverse foramina of cervical vertebrae were more common than bilateral. Also unilateral small size transverse foramina of cervical vertebrae were also common. This variation is important for the neurosurgeon during cervical surgery. Under such condition the course of the vertebral artery may be distorted. It is also useful for Radiologist during CT and MRI scan.

  18. Relation between intraocular pressure and size of transverse sinuses

    Energy Technology Data Exchange (ETDEWEB)

    Kantarci, Mecit; Onbas, Omer; Alper, Fatih; Okur, Adnan [Atatuerk University, Department of Radiology, Medical Faculty, Erzurum (Turkey); Dane, Senol; Gumustekin, Kenan [Atatuerk University, Department of Physiology, Medical Faculty, Erzurum (Turkey); Aslankurt, Murat [Atatuerk University, Department of Ophtalmatology, Medical Faculty, Erzurum (Turkey); Yazici, Ahmet Taylan [Beyoglu Goez Egitim ve Arastirma Hastanesi, Istanbul (Turkey)

    2005-01-01

    There are asymmetries in the sizes of transverse sinus and intraocular pressure. The purpose of this study was to investigate possible relationships between the asymmetry of transverse sinuses in TOF MR venography and intraocular pressures of right and left eyes. In this study, subjects were 63 male and 42 female medical school students, aged 18-21 years (mean{+-}SD; 19.72{+-}0.67 years). Subjects with neurological and ophthalmologic disease, particularly dural sinus thrombosis, myopia, trauma and glaucoma, were excluded the study. Subjects were divided into five groups according to the magnitudes of the right- and left-transverse sinuses in MR venography results. There is a functional relation between intraocular pressures of the right and left eyes and asymmetry of the transverse sinus. If the transverse sinus on one side is larger and its venous drainage is greater, the intraocular pressure of the eye on this side is lower. It can be speculated that the transverse sinus size may be associated with pathogenesis of diseases with increased intraocular pressure such as glaucoma. We aim to determine the relation between the size and drainage of transverse sinuses in TOF MR venography and intraocular pressure in patients with open-angle glaucoma in our next study. (orig.)

  19. Monitoring and imaging the atmosphere with infrasonic ambient noise correlations

    Science.gov (United States)

    Haney, Matthew; Evers, Laslo

    2010-05-01

    The existence of widespread infrasonic ambient noise (e.g., microbaroms) opens up the possibility of investigating atmospheric acoustic structure with new techniques designed for continuous stochastic signals. This is in contrast to classical approaches that use deterministic signals (e.g., explosions) with clear phase arrivals. Here, we review some recent advances in the monitoring and imaging of the atmosphere derived from analysis of continuous infrasound noise. From two microbarometers located at Fourpeaked Volcano in Alaska, we observe coherent arrivals in cross-correlations of ambient noise in the microbarom band (0.2-0.5 Hz) at time lags that agree well with speeds expected for a direct infrasound wave in the atmosphere (300-340 m/s). A striking example of the dependence of the ambient noise correlations on atmospheric conditions is evident from a comparison with temperature and wind data measured on nearby ocean buoys. Application of the multiple-filter technique reveals that the group velocity of the infrasound wave is dispersive, with higher group velocities at lower frequencies. This supports the existence of a low-level atmospheric waveguide at Fourpeaked Volcano during the time period under study. We invert the observed time-dependent group velocity dispersion curves for average sound speed profiles as a function of time. The inverted sound speed profiles show that a time-dependent, surface-based inversion layer became stronger over a period of 24 hours, with a colder, denser, and lower sound speed layer moving between the stations. This layer is imaged in the lower 2 km of the atmosphere and demonstrates the sensitivity of ambient noise correlations to the atmospheric boundary layer. Independent analysis of meteorological data in and around Fourpeaked volcano from the same time period supports the results derived from the infrasound ambient noise correlations. We also show examples of ambient noise correlations from time periods of normal temperature

  20. Rayleigh and Love Wave Phase Velocities in the Northern Gulf Coast of the United States

    Science.gov (United States)

    Li, A.; Yao, Y.

    2017-12-01

    The last major tectonic event in the northern Gulf Coast of the United States is Mesozoic continental rifting that formed the Gulf of Mexico. This area also experienced igneous activity and local uplifts during Cretaceous. To investigate lithosphere evolution associated with the rifting and igneous activity, we construct Rayleigh and Love wave phase velocity models at the periods of 6 s to 125 s in the northern Gulf Coast from Louisiana to Alabama including the eastern Ouachita and southern Appalachian orogeny. The phase velocities are derived from ambient noise and earthquake data recorded at the 120 USArray Transportable Array stations. At periods below 20 s, phase velocity maps are characterized by significant low velocities in the Interior Salt Basin and Gulf Coast Basin, reflecting the effects of thick sediments. The northern Louisiana and southern Arkansas are imaged as a low velocity anomaly in Rayleigh wave models but a high velocity anomaly of Love wave at the periods of 14 s to 30 s, indicating strong lower crust extension to the Ouachita front. High velocity is present in the Mississippi Valley Graben from period 20 s to 35 s, probably reflecting a thin crust or high-velocity lower crust. At longer periods, low velocities are along the Mississippi River to the Gulf Coast Basin, and high velocity anomaly mainly locates in the Black Warrior Basin between the Ouachita Belt and Appalachian Orogeny. The magnitude of anomalies in Love wave images is much smaller than that in Rayleigh wave models, which is probably due to radial anisotropy in the upper mantle. A 3-D anisotropic shear velocity model will be developed from the phase velocities and will provide more details for the crust and upper mantle structure beneath the northern Gulf of Mexico continental margin.

  1. 3-D S-velocity structure in the lowermost mantle beneath the Northern Pacific

    Science.gov (United States)

    Suzuki, Y.; Kawai, K.; Geller, R. J.; Borgeaud, A. F. E.; Konishi, K.

    2017-12-01

    We previously (Suzuki et al., EPS, 2016) reported the results of waveform inversion to infer the three-dimensional (3-D) S-velocity structure in the lowermost 400 km of the mantle (the Dʺ region) beneath the Northern Pacific region. Our dataset consists of about 20,000 transverse component broadband body-wave seismograms observed at North American stations (mainly USArray) for 131 intermediate and deep earthquakes which occurred beneath the western Pacific subduction region. Synthetic resolution tests indicate that our methods and dataset can resolve the velocity structure in the target region with a horizontal scale of about 150 km and a vertical scale of about 50 km. The 3-D S-velocity model obtained in that study shows three prominent features: (i) horizontal high-velocity anomalies up to about 3 per cent faster than the Preliminary Reference Earth Model (PREM) with a thickness of a few hundred km and a lower boundary which is at most about 150 km above the core-mantle boundary (CMB), (ii) low-velocity anomalies about 2.5 per cent slower than PREM beneath the high-velocity anomalies at the base of the lower mantle, (iii) a thin (about 150 km) low-velocity structure continuous from the base of the low-velocity zone to at least 400 km above the CMB. We interpret these features respectively as: (i) remnants of slab material where the Mg-perovskite to Mg-post-perovskite phase transition could have occurred within the slab, (ii, iii) large amounts of hot and less dense materials beneath the cold Kula or Pacific slab remnants immediately above the CMB which ascend and form a passive plume upwelling at the edge of the slab remnants. Since our initial work we subsequently conducted waveform inversion using both the transverse- and radial-component horizontal waveform data to infer the isotropic shear velocity structure in the lowermost mantle beneath the Northern Pacific in more detail. We also compute partial derivatives with respect to the 5 independent elastic

  2. Subsurface Characterization Beneath the Coso Geothermal Field by Ambient Noise Tomography

    Science.gov (United States)

    Ritzwoller, M. H.; Yang, Y.; Levshin, A. L.; Barmin, M. P.; Jones, C. H.

    2009-12-01

    The Coso Geothermal Area has been the subject of numerous geophysical studies over the past 30 years. Various seismological techniques have been applied to evaluate the regional stress distribution, velocity and attenuation structure of the subsurface. None of these studies has imaged subsurface shear velocity using surface waves generated either by local micro-earthquakes or by regional or teleseismic earthquakes, nor have any used interferometric methods based on ambient noise. In this study, we apply an interferometic method based on ambient seismic noise aimed at imaging the shallow shear velocity structure beneath the Coso Geothermal Area. Data are from a PASSCAL experiment deployed between 1998 and 2000 and regional broad-band seismometers operated by CalTech. Cross-correlations are performed between each pair of the COSO PASSCAL and CalTech stations for 15 months from March 1999 to May 2000. After compensating for or correcting instrumental irregularities and selecting reliable Rayleigh wave dispersion measurements from the inter-station cross-correlations, we obtain about 300 measurement paths as the basis for surface wave tomography at periods from 3 to 10 sec. Uncertainties of both group and phase velocity measurements are estimated using the variations among the dispersion curves from one-month cross-correlations in different months. The resulting dispersion maps reveal low group and phase velocities in the COSO volcanic field, especially at 3 sec period for group velocities, and high velocities to the east of the COSO volcanic field. The velocity variations are consistent with surface geological features, which encourages future inversion for 3-D shear velocity structure in the top 15 km of the crust.

  3. Propagation and dispersion of transverse wave trains in magnetic flux tubes

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, R.; Terradas, J. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Ruderman, M. S., E-mail: ramon.oliver@uib.es [School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2014-07-01

    The dispersion of small-amplitude, impulsively excited wave trains propagating along a magnetic flux tube is investigated. The initial disturbance is a localized transverse displacement of the tube that excites a fast kink wave packet. The spatial and temporal evolution of the perturbed variables (density, plasma displacement, velocity, ...) is given by an analytical expression containing an integral that is computed numerically. We find that the dispersion of fast kink wave trains is more important for shorter initial disturbances (i.e., more concentrated in the longitudinal direction) and for larger density ratios (i.e., for larger contrasts of the tube density with respect to the environment density). This type of excitation generates a wave train whose signature at a fixed position along a coronal loop is a short event (duration ≅ 20 s) in which the velocity and density oscillate very rapidly with typical periods of the order of a few seconds. The oscillatory period is not constant but gradually declines during the course of this event. Peak values of the velocity are of the order of 10 km s{sup –1} and are accompanied by maximum density variations of the order of 10%-15% the unperturbed loop density.

  4. A transversely isotropic medium with a tilted symmetry axis normal to the reflector

    KAUST Repository

    Alkhalifah, Tariq Ali

    2010-05-01

    The computational tools for imaging in transversely isotropic media with tilted axes of symmetry (TTI) are complex and in most cases do not have an explicit closed-form representation. Developing such tools for a TTI medium with tilt constrained to be normal to the reflector dip (DTI) reduces their complexity and allows for closed-form representations. The homogeneous-case zero-offset migration in such a medium can be performed using an isotropic operator scaled by the velocity of the medium in the tilt direction. For the nonzero-offset case, the reflection angle is always equal to the incidence angle, and thus, the velocities for the source and receiver waves at the reflection point are equal and explicitly dependent on the reflection angle. This fact allows for the development of explicit representations for angle decomposition as well as moveout formulas for analysis of extended images obtained by wave-equation migration. Although setting the tilt normal to the reflector dip may not be valid everywhere (i.e., on salt flanks), it can be used in the process of velocity model building, in which such constrains are useful and typically are used. © 2010 Society of Exploration Geophysicists.

  5. Migration using a transversely isotropic medium with symmetry normal to the reflector dip

    KAUST Repository

    Alkhalifah, Tariq Ali

    2011-01-01

    A transversely isotropic (TI) model in which the tilt is constrained to be normal to the dip (DTI model) allows for simplifications in the imaging and velocity model building efforts as compared to a general TI (TTI) model. Although this model cannot be represented physically in all situations, for example, in the case of conflicting dips, it handles arbitrary reflector orientations under the assumption of symmetry axis normal to the dip. Using this assumption, we obtain efficient downward continuation algorithms compared to the general TTI ones, by utilizing the reflection features of such a model. Phase-shift migration can be easily extended to approximately handle lateral inhomogeneity using, for example, the split-step approach. This is possible because, unlike the general TTI case, the DTI model reduces to VTI for zero dip. These features enable a process in which we can extract velocity information by including tools that expose inaccuracies in the velocity model in the downward continuation process. We test this model on synthetic data corresponding to a general TTI medium and show its resilience. 2011 Tariq Alkhalifah and Paul Sava.

  6. MHD modeling of ATLAS experiments to study transverse shear interface interactions

    CERN Document Server

    Faehl, R J; Keinigs, R K; Lindemuth, I R

    2001-01-01

    Summary form only given. The transverse shear established at the interface of two solids moving at differential velocities on the order of the sound speed is being studied in experiments on the ATLAS capacitor bank at Los Alamos, beginning in August 2001. The ATLAS bank has finished certification tests and has demonstrated peak currents of 27.5 MA with a 5 microsecond risetime into an inductive load. One- and two-dimensional MHD calculations have been performed in support of these "friction-like" ATLAS experiments. Current flowing along the outer surface of a thick aluminum liner, roughly 8 mm thick, accelerates the solid liner to velocities ~1 km/s. This cylindrically imploding liner then impacts a target assembly, composed of alternating regions of high and low density materials. The different shock speeds in the two materials leads to a differential velocity along the interface. Shock heating, elastic- plastic flow, and stress transport are included in the calculations. Material strength properties are tre...

  7. MEASURED TRANSVERSE COUPLING IMPEDANCE OF RHIC INJECTION AND ABORT KICKERS

    International Nuclear Information System (INIS)

    HAHN, H.; DAVINO, D.

    2001-01-01

    Concerns regarding possible transverse instabilities in RHIC and the SNS pointed to the need for measurements of the transverse coupling impedance of ring components. The impedance of the RHIC injection and abort kicker was measured using the conventional method based on the S 21 forward transmission coefficient. A commercial 450 Ω twin-wire Lecher line were used and the data was interpreted via the log-formula. All measurements, were performed in test stands fully representing operational conditions including pulsed power supplies and connecting cables. The measured values for the transverse coupling impedance in kick direction and perpendicular to it are comparable in magnitude, but differ from Handbook predictions

  8. Numerical simulation of transverse jet flow field under supersonic inflow

    Directory of Open Access Journals (Sweden)

    Qian Li

    2017-01-01

    Full Text Available Transverse jet flow field under supersonic inflow is simulated numerically for studying the characteristic of fuel transverse jet and fuel mixing in scramjet combustion chamber. Comparison is performed between simulated results and the results of references and experiments. Results indicate that the CFD code in this paper is applicable for simulation of transverse jut flow field under supersonic inflow, but in order to providing more effective numerical predictive method, CFD code should be modified through increasing mesh density and adding LES module.

  9. Measurement of the Transverse Spitzer Resistivity during Collisional Magnetic Reconnection

    International Nuclear Information System (INIS)

    Trintchouk, F.; Yamada, M.; Ji, H.; Kulsrud, R.M.; Carter, T.A.

    2000-01-01

    Measurement of the transverse resistivity was carried out in a reconnecting current sheet where the mean free path for the Coulomb collision is smaller than the thickness of the sheet. In a collisional neutral sheet without a guide field, the transverse resistivity is directly related to the reconnection rate. A remarkable agreement is found between the measured resistivity and the classical value derived by L. Spitzer. In his calculation the transverse resistivity for the electrons is higher than the parallel resistivity by a factor of 1.96. The measured values have verified this theory to within 30% errors

  10. Optical bistabilities of higher harmonics: Inhomogeneous and transverse effects

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, S.S., E-mail: Shoukryhassan@hotmail.com [Department of Mathematics, College of Science, University of Bahrain, P.O. Box 32038 (Bahrain); Manchester Metropolitan University, Dept. of Computing, Maths. and Digital Technology, Manchester M1 5GD (United Kingdom); Sharaby, Y.A., E-mail: Yasser_Sharaby@hotmail.com [Department of Physics, Faculty of Science, Suez Canal University, Suez (Egypt); Ali, M.F.M., E-mail: dr.mona.fathy@hotmail.com [Department of Mathematics: Faculty of Science, Ain Shams University, Cairo (Egypt); Joshi, A., E-mail: ajoshi@eiu.edu [Department of Physics, Eastern Illinois University, Charleston, IL 61920 (United States)

    2012-10-15

    The steady state behavior of optical bistable system in a ring cavity with transverse field variations and inhomogeneousely broadened two-level atoms is investigated outside the rotating wave approximation (RWA). Analytical and numerical investigation is presented for different cases of transverse field variations with Lorentzian or Gaussian line widths. When both (transverse and inhomogeneous) features taken into account, the first harmonic output field component outside the RWA exhibits a one-way switching down processes (butterfly OB) or reversed (clockwise) OB behavior, depending on the atomic linewidth shape.

  11. On flow of electrically conducting fluids over a flat plate in the presence of a transverse magnetic field

    Science.gov (United States)

    Rossow, Vernon J

    1958-01-01

    The use of a magnetic field to control the motion of electrically conducting fluids is studied. The incompressible boundary-layer solutions are found for flow over a flat plate when the magnetic field is fixed relative to the plate or to the fluid. The equations are integrated numerically for the effect of the transverse magnetic field on the velocity and temperature profiles, and hence, the skin friction and rate of heat transfer. It is concluded that the skin friction and the heat-transfer rate are reduced when the transverse magnetic field is fixed relative to the plate and increased when fixed relative to the fluid. The total drag is increased in all of the areas.

  12. The offset-midpoint traveltime pyramid in 3D transversely isotropic media with a horizontal symmetry axis

    KAUST Repository

    Hao, Qi

    2014-12-30

    Analytic representation of the offset-midpoint traveltime equation for anisotropy is very important for prestack Kirchhoff migration and velocity inversion in anisotropic media. For transversely isotropic media with a vertical symmetry axis, the offset-midpoint traveltime resembles the shape of a Cheops’ pyramid. This is also valid for homogeneous 3D transversely isotropic media with a horizontal symmetry axis (HTI). We extended the offset-midpoint traveltime pyramid to the case of homogeneous 3D HTI. Under the assumption of weak anellipticity of HTI media, we derived an analytic representation of the P-wave traveltime equation and used Shanks transformation to improve the accuracy of horizontal and vertical slownesses. The traveltime pyramid was derived in the depth and time domains. Numerical examples confirmed the accuracy of the proposed approximation for the traveltime function in 3D HTI media.

  13. Deep transverse friction massage for treating tendinitis.

    Science.gov (United States)

    Brosseau, L; Casimiro, L; Milne, S; Robinson, V; Shea, B; Tugwell, P; Wells, G

    2002-01-01

    Deep transverse friction massage (DTFM) is one of several physiotherapy interventions suggested for the management of pain due to iliotibial band friction syndrome (ITBFS). To assess the effectiveness of DTFM for treating ITBFS observed in runners. We searched the Medline, Embase, Healthstar, Sports Discus, CINAHL, the Cochrane Controlled Trials Register, PEDro, the specialized registry of the Cochrane musculoskeletal group and the Cochrane field of Physical and Related Therapies up to the end of December 2000, using the sensitive search strategy developed by the Cochrane Collaboration. The search was complemented with bibliography searching of the reference list of the trials retrieved from the electronic search. Key experts in the area were contacted for further published and unpublished articles. All randomized controlled trials (RCTs) and controlled clinical trials (CCTs) comparing therapeutic ultrasound against placebo or another active intervention in patients with patellofemoral pain syndrome were selected. Two reviewers determined the studies to be included based on inclusion and exclusion criteria (LB, VR). Data were independently abstracted by two reviewers (VR, LB), and checked by a third reviewer (BS) using a pre-developed form of the Cochrane Musculoskeletal Group. The same two reviewers, using a validated scale, assessed the methodological quality of the RCTs and CCTs independently. Iliotibial band friction syndrome outcome measures were extracted from the publications. The pooled analysis was performed using weighted mean differences (WMDs) for pain relief as described as 1) daily pain; 2) pain while running and 3) percentage of maximum pain when running. A chi-square test was used to assess heterogeneity among trials. Fixed effects models were used throughout and random effects for outcomes showing heterogeneity. One RCT, including 17 patients with ITBFS was included. The experimental group (DTFM combined to rest, stretching exercises, cryotherapy

  14. Active deformation offshore the Western Transverse Ranges

    Science.gov (United States)

    Ucarkus, G.; Driscoll, N. W.; Brothers, D. S.; Kent, G.; Rockwell, T. K.

    2014-12-01

    The Transverse Ranges within the structural province of southern California, an east-west trending active fold and thrust belt system, has rapid uplift rates that are capable of generating large earthquakes and tsunamis. This system to the west consists of north and south dipping reverse faults offshore Santa Barbara and Ventura (i.e., Pitas Point fault, Red Mountain fault, Rincon Creek fault). Ventura Avenue Anticline (VAA) is one of the fastest uplifting structure within this system has experienced nearly 2.7 km of structural uplift since fold initiation about 200-300 thousand years ago, yielding an average uplift rate of 9-13 mm/yr. Mapped and dated Holocene marine terraces between Ventura and Carpenteria reveal that large uplift events occurred at 0.8 ka and 1.9 ka; a recurrence interval of approximately a thousand years. The VAA trends offshore to the west and is buried by sediment from Rincon Creek. This sediment completely obscures the surficial expression of the fold between Rincon Point and Punta Gorda, indicating that Holocene sedimentation has kept pace with fold growth. Given the high sedimentation rate, each uplift event should be captured by stratigraphic rotation and onlap, and formation of angular unconformities. With that perspective, we acquired ~240 km-long very high-resolution (decimeter) CHIRP seismic reflection data from offshore Santa Barbara in the west to Ventura in the east, in order to examine discrete folding/uplift events that are preserved in the Holocene sediment record. CHIRP data together with re-processed USGS sparker profiles provide new constraints on timing and architecture of deformation offshore. A transgressive surface that dates back to ~9.5 kyr B.P is identified in seismic reflection data and dips landward; bending of the transgressive surface appears to be due to active folding and faulting. Observed onlapping sediments together with the deformation of the transgressive surface mark the onset of deformation while periods

  15. Velocity bunching of high-brightness electron beams

    Directory of Open Access Journals (Sweden)

    S. G. Anderson

    2005-01-01

    Full Text Available Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly

  16. Drift velocity and pressure monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2011-01-01

    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. Another important parameter to be monitored is the pressure inside the muon drift tube chambers. The differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest drift velocity monitoring results are discussed.

  17. Drift velocity and pressure 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. Another important parameter to be monitored is the pressure inside the muon drift tube chambers because the drift velocity depends on it. Furthermore the differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest pressure monitoring results are discussed.

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

    Science.gov (United States)

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

    2015-04-01

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

  19. Kaon transverse charge density from space- and timelike data

    Science.gov (United States)

    Mecholsky, N. A.; Meija-Ott, J.; Carmignotto, M.; Horn, T.; Miller, G. A.; Pegg, I. L.

    2017-12-01

    We used the world data on the kaon form factor to extract the transverse kaon charge density using a dispersion integral of the imaginary part of the kaon form factor in the timelike region. Our analysis includes recent data from e+e- annihiliation measurements extending the kinematic reach of the data into the region of high momentum transfers conjugate to the region of short transverse distances. To calculate the transverse density we created a superset of both timelike and spacelike data and developed an empirical parameterization of the kaon form factor. The spacelike set includes two new data points we extracted from existing cross section data. We estimate the uncertainty on the resulting transverse density to be 5% at b =0.025 fm and significantly better at large distances. New kaon data planned with the 12 GeV Jefferson Lab may have a significant impact on the charge density at distances of b <0.1 fm.

  20. Transverse momentum dependent (TMD) parton distribution functions : status and prospects

    NARCIS (Netherlands)

    Angeles-Martinez, R.; Bacchetta, A.; Balitsky, I.I.; Boer, D.; Boglione, M.; Boussarie, R.; Ceccopieri, F.A.; Cherednikov, I.O.; Connor, P.; Echevarria, M. G.; Ferrera, G.; Luyando, J. Grados; Hautmann, F.; Jung, H.; Kasemets, T.; Kutak, K.; Lansberg, J.P.; Lelek, A.; Lykasov, G.; Martinez, J. D. Madrigal; Mulders, P. J.; Nocera, Emanuele R.; Petreska, E.; Pisano, C.; Placakyte, R.; Radescu, V.; Radici, M.; Schnell, G.; Scimemi, I.; Signori, A.; Szymanowski, L.; Monfared, S. Taheri; van der Veken, F.F.; van Haevermaet, H.J.; van Mechelen, P.; Vladimirov, A.; Wallon, S.

    2015-01-01

    We review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of

  1. Haematoma in the transverse mesocolon secondary to acute ...

    African Journals Online (AJOL)

    A case of acute haematoma of the transverse mesocolon secondary to acute necrotizing pancreatitis is presented. with a brief discussion of the pathogenesis and computed tomographic findings. The value of computed tomography in acute complicated pancreatitis is emphasized.

  2. Interplay among transversity induced asymmetries in hadron leptoproduction

    CERN Document Server

    Adolph, C.; Alexeev, M.G.; Alexeev, G.D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Augustyniak, W.; Austregesilo, A.; Azevedo, C.D.R.; Badelek, B.; Balestra, F.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E.R.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Buchele, M.; Burtin, E.; Chang, W.C.; Chiosso, M.; Choi, I.; Chung, S.U.; Cicuttin, A.; Crespo, M.L.; Curiel, Q.; d'Hose, N.; Dalla Torre, S.; Dasgupta, S.S.; Dasgupta, S.; Denisov, O.Yu.; Dhara, L.; Donskov, S.V.; Doshita, N.; Duic, V.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P.D.; Eyrich, W.; Ferrero, A.; Finger, M.; M. Finger jr; Fischer, H.; Franco, C.; von Hohenesche, N. du Fresne; Friedrich, J.M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmuller, S.; Grasso, A.; Grosse-Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F.H.; Herrmann, F.; Hinterberger, F.; Horikawa, N.; Hsieh, C.Yu; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jorg, P.; Joosten, R.; Kabuss, E.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J.H.; Kolosov, V.N.; Kondo, K.; Konigsmann, K.; Konorov, I.; Konstantinov, V.F.; Kotzinian, A.M.; Kouznetsov, O.; Kramer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z.V.; Kuchinski, N.; Kunne, F.; Kurek, K.; Kurjata, R.P.; Lednev, A.A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G.K.; Marchand, C.; Marianski, B.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Montuenga, P.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nikolaenko, V.I.; Novy, J.; Nowak, W.D.; Nukazuka, G.; Nunes, A.S.; Olshevsky, A.G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.C.; Pereira, F.; Pesaro, G.; Pesek, M.; Peshekhonov, D.V.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Rossiyskaya, N.S.; Ryabchikov, D.I.; Rychter, A.; Samoylenko, V.D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I.A.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schonning, K.; Schopferer, S.; Selyunin, A.; Shevchenko, O.Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Wolbeek, J. ter; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Weisrock, T.; Wilfert, M.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

    2016-01-01

    In the fragmentation of a transversely polarized quark several left-right asymmetries are possible for the hadrons in the jet. When only one unpolarized hadron is selected, it exhibits an azimuthal modulation known as Collins effect. When a pair of oppositely charged hadrons is observed, three asymmetries can be considered, a di-hadron asymmetry and two single hadron asymmetries. In lepton deep inelastic scattering on transversely polarized nucleons all these asymmetries are coupled with the transversity distribution. From the high statistics COMPASS data on oppositely charged hadron-pair production we have investigated for the first time the dependence of these three asymmetries on the difference of the azimuthal angles of the two hadrons. The similarity of transversity induced single and di-hadron asymmetries is discussed. A phenomenological analysis of the data allows to establish quantitative relationships among them, providing strong indication that the underlying fragmentation mechanisms are all driven ...

  3. Evaluation of transverse joint forming methods for PCC pavement.

    Science.gov (United States)

    2006-01-01

    The members of the Iowa Concrete Paving Association, the National Concrete Pavement Technology Center Research Committee, and : the Iowa Highway Research Board commissioned a study to examine alternative ways of developing transverse joints in portla...

  4. Jet axes and universal transverse-momentum- dependent fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Neill, Duff [Theoretical Division, MS B283, Los Alamos National Laboratory,Los Alamos, NM 87545 (United States); Scimemi, Ignazio [Departamento de Física Teórica II, Universidad Complutense de Madrid,Ciudad Universitaria, 28040 Madrid (Spain); Waalewijn, Wouter J. [Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics,University of Amsterdam,Science Park 904, 1098 XH Amsterdam (Netherlands); Nikhef, Theory Group,Science Park 105, 1098 XG, Amsterdam (Netherlands)

    2017-04-04

    We study the transverse momentum spectrum of hadrons in jets. By measuring the transverse momentum with respect to a judiciously chosen axis, we find that this observable is insensitive to (the recoil of) soft radiation. Furthermore, for small transverse momenta we show that the effects of the jet boundary factorize, leading to a new transverse-momentum-dependent (TMD) fragmentation function. In contrast to the usual TMD fragmentation functions, it does not involve rapidity divergences and is universal in the sense that it is independent of the type of process and number of jets. These results directly apply to sub-jets instead of hadrons. We discuss potential applications, which include studying nuclear modification effects in heavy-ion collisions and identifying boosted heavy resonances.

  5. Transverse momentum in double parton scattering. Factorisation, evolution and matching

    International Nuclear Information System (INIS)

    Buffing, Maarten G.A.; Diehl, Markus; Kasemets, Tomas

    2017-08-01

    We give a description of double parton scattering with measured transverse momenta in the final state, extending the formalism for factorisation and resummation developed by Collins, Soper and Sterman for the production of colourless particles. After a detailed analysis of their colour structure, we derive and solve evolution equations in rapidity and renormalisation scale for the relevant soft factors and double parton distributions. We show how in the perturbative regime, transverse momentum dependent double parton distributions can be expressed in terms of simpler nonperturbative quantities and compute several of the corresponding perturbative kernels at one-loop accuracy. We then show how the coherent sum of single and double parton scattering can be simplified for perturbatively large transverse momenta, and we discuss to which order resummation can be performed with presently available results. As an auxiliary result, we derive a simple form for the square root factor in the Collins construction of transverse momentum dependent parton distributions.

  6. Ductile-brittle transition in transverse isotropic fibrous networks

    Science.gov (United States)

    Luo, Guoquan; Shi, Liping; Li, Mingwei; Zhong, Yesheng; He, Xiaodong; Wang, Jiazhi

    2018-01-01

    Anisotropic fibrous networks, especially transverse isotropic fibrous networks, are widely used to model the microstructures of biological tissues, polymer gels, fibrous thermal insulations, and other fibrous materials. In this letter, we build a three-dimensional transverse isotropic fibrous network model and study its mechanical properties along the through-thickness direction. We propose a measurement of anisotropy for transverse isotropic fibrous networks and then study the influence of anisotropy on the networks' mechanical properties, including its elastic modulus, maximum elongation, and stress-strain curve, by means of finite-element simulation. We also study theoretically the influence of anisotropy on maximum elongation. We find that as the anisotropy of the networks becomes stronger, the elastic modulus decreases and the maximum elongation increases, indicating a transition in mechanical properties from brittle to ductile. We identify this transition as the "ductile-brittle transition." This transition can help guide the design and regulate the mechanical properties of a transverse isotropic fibrous network.

  7. Transverse Compression Response of a Multi-Ply Kevlar Vest

    National Research Council Canada - National Science Library

    Raftenberg, Martin N; Scheidler, Michael J; Moy, Paul

    2004-01-01

    Each of the two 38 X 38-cm square panels, consisting of 28 plies of plain-woven 600-denier Kevlar KM2 and a Cordura case, was loaded in quasistatic, transverse compression by means of an Instron machine...

  8. Progress In Transverse Feedbacks and Related Diagnostics for Hadron Machines

    CERN Document Server

    Hofle, W

    2013-01-01

    Today Hadron Accelerators with high intensity and high brightness beams increasingly rely on transverse feedback systems for the control of instabilities and the preservation of the transverse emittance. With particular emphasis, but not limited to, the CERN Hadron Accelerator Chain, the progress made in recent years, and the performances achieved are reviewed. Hadron colliders such as the LHC represent a particular challenge as they ask for low noise electronic systems in these feedbacks for acceptable emittance growth. Achievements of the LHC transverse feedback system used for damping injection oscillations and to provide stability throughout the cycle are summarized. This includes its use for abort gap and injection cleaning as well as transverse blow-up for diagnostics purposes. Beyond systems already in operation, advances in technology and modern digital signal processing with increasingly higher digitization rates have made systems conceivable to cure intra-bunch motion. With its capabilities to both ...

  9. Analysis of tap weight errors in CCD transversal filters

    NARCIS (Netherlands)

    Ricco, Bruno; Wallinga, Hans

    1978-01-01

    A method is presented to determine and evaluate the actual tap weight errors in CCD split-electrode transversal filters. It is concluded that the correlated part in the tap weight errors dominates the random errors.

  10. Transverse testicular ectopia with persistent Mullerian duct syndrome

    African Journals Online (AJOL)

    mail: amingoh@gmail.com. Received 30 September 2011 accepted 12 February 2012. Introduction. Transverse testicular ectopia (TTE) associated with persistent Mullerian duct syndrome (PMDS) is a rare anomaly that can be encountered ...

  11. Effect of Transverse Coupling on Asymmetric Cooling in Compton Rings

    CERN Document Server

    Bulyak, E; Zimmermann, F

    2013-01-01

    Fast cooling of bunches circulating in a Compton ring is achieved by placing the collision point between electron bunches and laser pulses in a dispersive section and by, in addition, introducing a transverse offset between the laser pulse and the electron-beam closed orbit. Growth of the emittance in the dispersive transversal direction due to the additional excitation of betatron oscillations limits this type of cooling. Here we present the results of further studies on the fast cooling process, looking at the effect of the coupling of the transverse (betatron) oscillations. We first show theoretically that the transverse betatron coupling shortens the cooling time and hence reduces the steady-state energy spread of the electron beam, as well as the quantum losses. The theoretical estimates are then validated by simulations. Finally, a proof-of-principle experiment at the KEK ATF Damping Ring is proposed.

  12. A&T Sector Note on the PS transverse feedback

    CERN Document Server

    Coly, Marcel; Blas, Alfred; Sterbini, Guido; CERN. Geneva. ATS Department

    2017-01-01

    In a particle accelerator, several contributions can degrade the beam quality and particularly the beam transverse emittance. In this document we will describe a system used in the CERN Proton Synchrotron (PS) to cope with the injection steering errors and the transverse instabilities: the PS transverse feedback (PS TFB). As time progresses, this system is also being used for other purpose, to increase in a controlled way the beam transverse emittance and to excite the beam for the Multi-Turn-Extraction (MTE). In 2016, it has been successfully used on some operational beams to damp injection oscillations. This allowed to test the reliability of the system for its operational deployment. A piquet service is available in case of problem.

  13. Fiber amplifiers under thermal loads leading to transverse mode instability

    DEFF Research Database (Denmark)

    Johansen, Mette Marie; Hansen, Kristian Rymann; Alkeskjold, Thomas Tanggaard

    2014-01-01

    Transverse mode instability (TMI) in rare-earth doped fiber amplifiers operating above an average power threshold is caused by intermodal stimulated thermal Rayleigh scattering due to quantum defect heating. We investigate thermally induced longitudinal waveguide perturbations causing power trans...

  14. Ozone deposition to an oat crop ( Avena sativa L.) grown in open-top chambers and in the ambient air

    Science.gov (United States)

    Pleijel, H.; Wallin, G.; Karlsson, P. E.; Skarby, L.; Sellden, G.

    Fluxes and deposition velocities for ozone were determined for open-top chambers with and without an oat crop, and for the adjacent field, using a resistance analogue model and the aerodynamic wind-profile method, respectively. During a period when the canopy was green and the ambient wind speeds modest, the fluxes and deposition velocities were higher in the chamber with plants than in the field crop. The deposition to chamber walls and soil in the chamber only accounted for part of that difference. The deposition velocity for ozone to the crop was light-dependent both in the chamber with plants and in the ambient air. With increasing plant senescence, the deposition velocity declined and the light dependence disappeared. Fluctuations in deposition velocity superimposed on the overall declining trend followed the same temporal pattern in the chambers with and without plants. These fluctuations in deposition velocity may partly be explained by variations in surface wetness. Differences in boundary layer conductance between chamber and ambient, which under certain conditions may significantly influence the validity of the chamber as a test system, were observed.

  15. educación ambiental

    Directory of Open Access Journals (Sweden)

    Fernando Ojeda Barceló

    2008-01-01

    Full Text Available Las Tecnologías de la Información y Comunicación (TICs pueden constituir una herramienta de primer orden para la Educación Ambiental para la Sostenibilidad (EApS, pero todavía existe cierta reticencia por parte de educadores ambientales a hacer un uso de ellas de forma habitual. El objetivo fundamental de este trabajo es ofrecer una revisión del estado de la cuestión tanto a nivel nacional como internacional e intentar hacer una propuesta didáctica de trabajo colaborativo a través de Internet para estudiantes de secundaria.

  16. Responsabilidades municipales en materia ambiental

    OpenAIRE

    Ignacio Pichardo Pagaza

    2009-01-01

    Los municipios tienen una responsabilidad directa, inmediata e ineludible hacia el medio ambiente que hasta hace pocos años no reconocían como pri mor dial sino como una función secundaria. Hoy es más que una obligación jurídica, es un compromiso so cial del nivel de gobierno más cercano a la sociedad. Este trabajo reflexiona en torno a las responsabilidades que la Constitución política impone de manera exclusiva a los municipios y que por su naturaleza tienen efectos directos en el medio ...

  17. Pediatria ambiental: um tema emergente

    Directory of Open Access Journals (Sweden)

    Patricia M. Valenzuela

    2011-04-01

    Full Text Available OBJETIVO: Revisar os artigos mais relevantes sobre a pediatria ambiental, seus efeitos potenciais para a saúde e, especialmente, seus avanços na prevenção. FONTES DOS DADOS: Foi realizada uma pesquisa utilizando as bases de dados MEDLINE/PubMed e SciELO. Foram revisados artigos de 1990 a 2010, além de capítulos de livros relacionados à pediatria ambiental. SÍNTESE DOS DADOS: Há uma variedade significativa de fatores que tornam as crianças altamente vulneráveis à exposição a riscos ambientais, associados principalmente ao consumo comparativamente maior de água, comida e ar por parte da criança, em relação ao seu peso corporal. De acordo com a Organização Mundial de Saúde, mais de 3 milhões de crianças menores de 5 anos morrem devido a doenças relacionadas ao meio ambiente. Aproximadamente 30-40% das doenças pediátricas estão relacionadas a fatores ambientais. As crianças estão constantemente expostas a vários riscos ambientais para a saúde, dentre os quais se destacam: água contaminada, falta de condições adequadas de saneamento, poluição do ar, vetores de doenças, perigos químicos, injúrias e acidentes. CONCLUSÕES: Atualmente, os pediatras são desafiados a tratar das necessidades de saúde ligadas à pediatria ambiental. A história pediátrica deve ser mais abrangente, acrescentando-se questões pontuais que ajudem a identificar potenciais riscos ambientais. A conscientização e o entendimento sobre os efeitos nocivos das várias condições ambientais e o conhecimento sobre as medidas de prevenção relacionadas resultarão em intervenções oportunas e adequadas que melhorarão a saúde e o desenvolvimento das nossas crianças.

  18. Periodismo ambiental y periodismo sostenible

    OpenAIRE

    Fernández Reyes, Rogelio

    2004-01-01

    En el presente artículo trataremos sobre el periodismo ambiental, para luego procurar teorizar sobre el periodismo sostenible. Finalizaremos deteniéndonos en los rasgos comunes y diferencias. El desarrollo sostenible es un nuevo modelo en la relación del ser humano con el entorno. En los medios de comunicación, cada vez aparecen más informaciones ambientales que se refieren a contenidos de este nuevo modelo. ¿Podemos hablar de periodismo sostenible? Nos decantamos por el sí, como una sub-espe...

  19. Shape analysis for mobile ambients

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2001-01-01

    The ambient calculus is a calculus of computation that allows active processes to move between sites. We present an analysis inspired by state-of-the-art pointer analyses that safely and accurately predicts which processes may turn up at what sites during the execution of a composite system....... The analysis models sets of processes by sets of regular tree grammars enhanced with context dependent counts, and it obtains its precision by combining a powerful redex materialisation with a strong redex reduction (in the manner of the strong updates performed in pointer analyses)....

  20. Los volcanes del Sistema Volcánico Transversal

    Directory of Open Access Journals (Sweden)

    Esperanza Yarza de la Torre

    2012-02-01

    Full Text Available Si hizo la selección de textos referentes a algunos de los volcanes que integran el Sistema Volcánico Transversal. Publicado en: Yarza de De la Torre, E. (1992, "Los volcanes del Sistema Volcánico Transversal", Volcanes de México, 4a ed. corregida y aumentada, Instituto de Geografía, UNAM, México, pp. 82-83, 89-136.

  1. Los volcanes del Sistema Volcánico Transversal

    OpenAIRE

    Esperanza Yarza de De la Torre

    2003-01-01

    Si hizo la selección de textos referentes a algunos de los volcanes que integran el Sistema Volcánico Transversal. Publicado en: Yarza de De la Torre, E. (1992), "Los volcanes del Sistema Volcánico Transversal", Volcanes de México, 4a ed. corregida y aumentada, Instituto de Geografía, UNAM, México, pp. 82-83, 89-136.

  2. Transverse flow of kaons in heavy-ion collisions

    CERN Document Server

    Zheng Yu Ming; Fuchs, C; Faessler, A; Xiao Wu; Hua Da Ping; Yan Yu Peng

    2002-01-01

    The transverse flow of positively charged kaons from heavy-ion collisions at intermediate energy is investigated within the framework of the quantum molecular dynamics model. The calculated results show that the experimental data are only consistent with those including the kaon mean-field potential from the chiral Lagrangian. This indicates that the transverse flow pattern of kaons is a useful probe of the kaon potential in a nuclear medium

  3. Transverse Momentum Distributions of Electron in Simulated QED Model

    Science.gov (United States)

    Kaur, Navdeep; Dahiya, Harleen

    2018-05-01

    In the present work, we have studied the transverse momentum distributions (TMDs) for the electron in simulated QED model. We have used the overlap representation of light-front wave functions where the spin-1/2 relativistic composite system consists of spin-1/2 fermion and spin-1 vector boson. The results have been obtained for T-even TMDs in transverse momentum plane for fixed value of longitudinal momentum fraction x.

  4. Transverse force on a vortex in lattice models of superfluids

    OpenAIRE

    Sonin, E. B.

    2013-01-01

    The paper derives the transverse forces (the Magnus and the Lorentz forces) in the lattice models of superfluids in the continuous approximation. The continuous approximation restores translational invariance absent in the original lattice model, but the theory is not Galilean invariant. As a result, calculation of the two transverse forces on the vortex, Magnus force and Lorentz force, requires the analysis of two balances, for the true momentum of particles in the lattice (Magnus force) and...

  5. Transverse confinement in stochastic cooling of trapped atoms

    International Nuclear Information System (INIS)

    Ivanov, D; Wallentowitz, S

    2004-01-01

    Stochastic cooling of trapped atoms is considered for a laser-beam configuration with beam waists equal to or smaller than the extent of the atomic cloud. It is shown that various effects appear due to this transverse confinement, among them heating of transverse kinetic energy. Analytical results of the cooling in dependence on size and location of the laser beam are presented for the case of a non-degenerate vapour

  6. 3D Models of a Transversal Flux Inductor

    Directory of Open Access Journals (Sweden)

    POPA Monica

    2014-05-01

    Full Text Available This paper deals with 3D numerical models of transverse flux inductor with a flexible electromagnetic configuration developed in Flux3D software. The simplified 3D model is coupled with a simplex optimization algorithm in order to attain a maximum uniformity of the transversal profile of power developed within the metallic sheet. The complex 3D model is used for a thoroughly analysis of device.

  7. Transverse expansion in 197 Au + 197 Au collisions at RHIC

    International Nuclear Information System (INIS)

    Cheng, Y.; Liu, F.; Liu, K.; Schweda, K.; Xu, N.

    2003-01-01

    Using the RQMD model, transverse momentum distributions and particle ratios are studied for 197 Au + 197 Au collisions at √s NN = 200 GeV. In particular, they present results on the mean transverse momentum of charged pions, charged kaons, protons and anti-protons and compare with experimental measurements. They discuss an approach to study early partonic collectivity in high energy nuclear collisions

  8. Transverse intrinsic localized modes in monatomic chain and in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Hizhnyakov, V. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Klopov, M. [Department of Physics, Faculty of Science, Tallinn University of Technology, Ehitajate 5, 19086 Tallinn (Estonia); Shelkan, A., E-mail: shell@ut.ee [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

    2016-03-06

    In this paper an analytical and numerical study of anharmonic vibrations of monatomic chain and graphene in transverse (perpendicular) with respect to the chain/plane direction is presented. Due to the lack of odd anharmonicities and presence of hard quartic anharmonicity for displacements in this direction, there may exist localized anharmonic transverse modes with the frequencies above the spectrum of the corresponding phonons. Although these frequencies are in resonance with longitudinal (chain) or in-plane (graphene) phonons, the modes can decay only due to a weak anharmonic process. Therefore the lifetime of these vibrations may be very long. E.g. in the chain, according to our theoretical and numerical calculations it may exceed 10{sup 10} periods. We call these vibrations as transverse intrinsic localized modes. - Highlights: • In a stretched monatomic chain, long-living nonlinear transverse localized modes may exist. • Transverse vibrations of a chain slowly decay due to creation of longitudinal phonons. • Lifetime of transverse vibrations of a chain may exceed billion periods of vibrations. • In stretched graphene, long-living out-of-plain localized vibrations may exist.

  9. Normal planar undulators doubling as transverse gradient undulators

    Directory of Open Access Journals (Sweden)

    Qika Jia

    2017-02-01

    Full Text Available The transverse gradient undulator (TGU has important application in the short-wavelength high-gain free electron lasers (FELs driven by laser-plasma accelerators. However, the usual transversely tapered TGUs need special design and manufacture, and the transverse gradient cannot be tuned arbitrarily. In this paper we explore a new and simple method of using the natural transverse gradient of a normal planar undulator to compensate the beam energy spread effect. In this method, a vertical dispersion on the electron beam is introduced, then the dispersed beam passes through a normal undulator with a vertical off-axis orbit where the vertical field gradient is selected properly related to the dispersion strength and the beam energy spread. Theoretical analysis and numerical simulations for self-amplified spontaneous emission FELs based on laser plasma accelerators are presented, and indicate that this method can greatly reduce the effect of the beam energy spread, leading to a similar enhancement on FEL performance as the usual transversely tapered TGU, but with the advantages of economy, tunable transverse gradient and no demand of extra field for correcting the orbit deflection induced by the field gradient.

  10. Ultrarelativistic transverse momentum distribution of the Tsallis statistics

    Energy Technology Data Exchange (ETDEWEB)

    Parvan, A.S. [Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation); Horia Hulubei National Institute of Physics and Nuclear Engineering, Department of Theoretical Physics, Bucharest-Magurele (Romania); Moldova Academy of Sciences, Institute of Applied Physics, Chisinau (Moldova, Republic of)

    2017-03-15

    The analytical expressions for the ultrarelativistic transverse momentum distributions of the Tsallis and the Tsallis-2 statistics were obtained. We found that the transverse momentum distribution of the Tsallis-factorized statistics, which is now largely used to describe the experimental transverse momentum spectra of hadrons measured in pp collisions at LHC and RHIC energies, in the ultrarelativistic case is not equivalent to the transverse momentum distributions of the Tsallis and the Tsallis-2 statistics. However, we revealed that this distribution exactly coincides with the transverse momentum distribution of the Tsallis-2 statistics in the zeroth term approximation and is transformed to the transverse momentum distribution of the Tsallis statistics in the zeroth term approximation by changing the parameter q to 1/q{sub c}. We demonstrated analytically on the basis of the ultrarelativistic ideal gas that the Tsallis-factorized statistics is not equivalent to the Tsallis and the Tsallis-2 statistics. In the present paper the Tsallis statistics corresponds to the standard expectation values. (orig.)

  11. Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.; Nakagawa, S.; Reverdy, F.; Meyer, L.R.; Duranti, L.; Ball, G.

    2010-12-15

    Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.

  12. Love waves propagation in a transversely isotropic piezoelectric layer on a piezomagnetic half-space.

    Science.gov (United States)

    Ezzin, Hamdi; Ben Amor, Morched; Ben Ghozlen, Mohamed Hédi

    2016-07-01

    A theoretical approach is taken into consideration to investigate Love wave propagation in a transversely isotropic piezoelectric layer on a piezomagnetic half-space. The magneto-electrically open and short conditions are applied to solve the problem. The phase and group velocity of the Love wave is numerically calculated for the magneto-electrically open and short cases, respectively. The variations of magneto-electromechanical coupling factor, mechanical displacements, electric and magnetic potentials along the thickness direction of the layers are obtained and discussed. The numerical results clearly show the influence of different stacking sequences on dispersion curves and on magneto-electromechanical coupling factor. This work may be relevant to analysis and design of various acoustic surface wave devices constructed from piezoelectric and piezomagnetic materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Effect of Air Velocity on Thermal Comfort in an Automobile Cabin

    Directory of Open Access Journals (Sweden)

    Mehmet Özgün Korukçu

    2011-06-01

    Full Text Available The aim of this study is to evaluate the effect of air velocity on thermal comfort during heating period in an automobile cabin with experiments. In the evaluation of comfort in automobiles, in general temperature, humidity, air velocity and radiant temperature measurements are taken. In the study, ambient temperature, relative humidity, mean radiant temperature and mean skin temperature of the driver inside the automobile cabin during heating for different vent air mass flow rates were measured in a parked car. Subjective survey was performed during the experiments to the driver. The results for different vent air mass flow rate values were compared with answers taken from the subject and discussed.

  14. Transverse plane rotation of the foot and transverse hip and pelvic kinematics in diplegic cerebral palsy.

    Science.gov (United States)

    Gaston, M S; Rutz, E; Dreher, T; Brunner, R

    2011-06-01

    External rotation of the foot associated with mid-foot break is a commonly observed gait abnormality in diplegic CP patients. Previous studies have shown a correlation between equinus and internal hip rotation in hemiplegic patients. This study aimed to determine if there was a correlation between the amount of transverse plane rotation in diplegic CP patients using kinematic data from standardised gait analysis. Lower limb data of 134 ambulant children with diplegic CP was analysed retrospectively determining the maximum change in foot, hip and pelvis rotation during loading response. Highly significant negative correlations (P=foot and hip movements and foot and pelvic movements. Equinus at initial contact diminished the foot:hip correlation while it enhanced the foot:pelvic correlation. There was less external rotation of the foot in equinus patients (P=0.012) and more external rotation of the pelvis in the equinus group (P=plane rotation at foot level to that at the hip and pelvis. The likely biomechanical explanation is relatively excessive transverse external rotation of the foot due to abnormalities such as mid-foot break. When under load, where the foot is fixed to the floor, internal rotation of the entire leg occurs. This is due to lever arm disease as a result of the relatively shortened foot and inefficiency of the plantar-flexion knee-extension couple. Equinus modulates the effect. When treating such patients, lever arm deformities at all levels must be considered to result in the best outcome and prevent recurrences. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Decoupled equations for reverse time migration in tilted transversely isotropic media

    KAUST Repository

    Zhan, Ge

    2012-03-01

    Conventional modeling and migration for tilted transversely isotropic (TTI) media may suffer from numerical instabilities and shear wave artifacts due to the coupling of the P-wave and SV-wave modes in the TTI coupled equations. Starting with the separated P- and SV-phase velocity expressions for vertical transversely isotropic (VTI) media, we extend these decoupled equations for modeling and reverse time migration (RTM) in acoustic TTI media. Compared with the TTI coupled equations published in the geophysical literature, the new TTI decoupled equations provide a more stable solution due to the complete separation of the P-wave and SV-wave modes. The pseudospectral method is the most convenient method to implement these equations due to the form of wavenumber expressions and has the added benefit of being highly accurate and thus avoiding numerical dispersion. The rapid expansion method (REM) in time is employed to produce a broad band numerically stable time evolution of the wavefields. Synthetic results validate the proposed TTI decoupled equations and show that modeling and RTM in TTI media with the decoupled equations remain numerically stable even for models with strong anisotropy and sharp contrasts. © 2012 Society of Exploration Geophysicists.

  16. Transverse Cascade and Sustenance of Turbulence in Keplerian Disks with an Azimuthal Magnetic Field

    Science.gov (United States)

    Gogichaishvili, D.; Mamatsashvili, G.; Horton, W.; Chagelishvili, G.; Bodo, G.

    2017-10-01

    The magnetorotational instability (MRI) in the sheared rotational Keplerian explains fundamental problems for both astrophysics and toroidal laboratory plasmas. The turbulence occurs before the threshold for the linear eigen modes. The work shows the turbulence occurs in nonzero toroidal magnetic field with a sheared toroidal flow velocity. We analyze the turbulence in Fourier k-space and x-space each time step to clarify the nonlinear energy-momentum transfers that produce the sustenance in the linearly stable plasma. The nonlinear process is a type 3D angular redistribution of modes in Fourier space - a transverse cascade - rather than the direct/inverse cascades. The turbulence is sustained an interplay of the linear transient growth from the radial gradient of the toroidal velocity (which is the only energy supply for the turbulence) and the transverse cascade. There is a relatively small ``vital area in Fourier space'' is crucial for the sustenance. Outside the vital area the direct cascade dominates. The interplay of the linear and nonlinear processes is generally too intertwined in k-space for a classical turbulence characterization. Subcycles occur from the interactions that maintain self-organization nonlinear turbulence. The spectral characteristics in four simulations are similar showing the universality of the sustenance mechanism of the shear flow driven MHDs-turbulence. Funded by the US Department of Energy under Grant DE-FG02-04ER54742 and the Space and Geophysics Laboratory at the University of Texas at Austin. G. Mamatsashvili is supported by the Alexander von Humboldt Foundation, Germany.

  17. On the nature of transverse coronal waves revealed by wavefront dislocations

    Science.gov (United States)

    López Ariste, A.; Luna, M.; Arregui, I.; Khomenko, E.; Collados, M.

    2015-07-01

    Context. Coronal waves are an important aspect of the dynamics of the plasma in the corona. Wavefront dislocations are topological features of most waves in nature and also of magnetohydrodynamic waves. Are there dislocations in coronal waves? Aims: The finding and explanation of dislocations may shed light on the nature and characteristics of the propagating waves, their interaction in the corona, and in general on the plasma dynamics. Methods: We positively identify dislocations in coronal waves observed by the Coronal Multi-channel Polarimeter (CoMP) as singularities in the Doppler shifts of emission coronal lines. We study the possible singularities that can be expected in coronal waves and try to reproduce the observed dislocations in terms of localization and frequency of appearance. Results: The observed dislocations can only be explained by the interference of a kink and sausage wave modes propagating with different frequencies along the coronal magnetic field. In the plane transverse to the propagation, the cross-section of the oscillating plasma must be smaller than the spatial resolution, and the two waves result in net longitudinal and transverse velocity components that are mixed through projection onto the line of sight. Alfvén waves can be responsible for the kink mode, but a magnetoacoustic sausage mode is necessary in all cases. Higher (flute) modes are excluded. The kink mode has a pressure amplitude that is less than the pressure amplitude of the sausage mode, though its observed velocity is higher. This concentrates dislocations on the top of the loop. Conclusions: To explain dislocations, any model of coronal waves must include the simultaneous propagation and interference of kink and sausage wave modes of comparable but different frequencies with a sausage wave amplitude much smaller than the kink one. Appendix A is available in electronic form at http://www.aanda.org

  18. Passband widening of transversely coupled resonator filters using the fundamental symmetric and antisymmetric modes.

    Science.gov (United States)

    Tsutsumi, J; Ikata, O; Satoh, Y

    2001-09-01

    This paper describes a method for widening the passband of transversely coupled resonator filters (TCF) using only the fundamental symmetric and antisymmetric modes. The coupling of modes analysis in the transverse direction is applied to the TCF design to investigate the passband width. As a result, it is found that the passband width can be increased by making the surface acoustic wave (SAW) velocity difference between the interdigital transducer (IDT) region and the resonator gap region smaller. It is proposed that a grating structure be applied to the common ground bar, instead of the uniform metal, to reduce the SAW velocity difference. Using the grating-type common ground bar, filters are fabricated on ST-quartz substrate. The passband of a single filter with a center frequency of 248 MHz is widened up to 410 kHz without any increase of the insertion loss. The effect of the impedance mismatch at the junction of two cascaded devices is investigated. It is shown that the filter performance is improved by reduction of the small parasitic capacitance existing at the cascade point. Experimentally, the capacitance formed between the bus bar of the IDT and the bottom surface of the ceramic package is reduced. The insertion loss is reduced by 0.6 dB, and 3-dB passband is widened by 8 kHz for a filter with a center frequency of 248 MHz. On the basis of these two improvements, cascaded TCFs are fabricated. For a filter with a center frequency of 248 MHz, an insertion loss of 5.5 dB and a 3-dB passband width of 270 kHz are obtained.

  19. Ambient air pollution and low birth weight

    DEFF Research Database (Denmark)

    Westergaard, Nadja; Gehring, Ulrike; Slama, Rémy

    2017-01-01

    Background and objectives: Ambient air pollution is controllable, and it is one of the greatest environmental threats to human health. Studies conducted worldwide have provided evidence that maternal exposure to ambient air pollution during pregnancy enhances the risk of low birth weight at term...... the effect of ambient air pollution. The aim of this commentary is to review the published literature on the association between ambient air pollution and TLBW regarding increased vulnerability for the above-mentioned subgroups.  Results: Although more than fifty epidemiological studies have examined...... the associations between ambient air pollution and TLBW to date, we only identified six studies that examined the potential effect modification of the association between ambient air pollution and TLBW by the above listed maternal risk factors. Two studies assessed effect modification caused by smoking...

  20. 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