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...
Spectral Velocity Estimation in the Transverse Direction
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt
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...... for creating the lateral oscillation. Pulsatile flow in a femoral artery placed 40 mm from the transducer is simulated for one cardiac cycle using the Womersly-Evan’s flow model. The bias of the mean estimated frequency is 13.6% compared to the true velocity and the mean relative std is 14.3%. This...
Maximum Possible Transverse Velocity in Special Relativity.
Medhekar, Sarang
1991-01-01
Using a physical picture, an expression for the maximum possible transverse velocity and orientation required for that by a linear emitter in special theory of relativity has been derived. A differential calculus method is also used to derive the expression. (Author/KR)
Xu, Zongbo; Xia, Jianghai; Luo, Yinhe; Cheng, Feng; Pan, Yudi
2016-04-01
People have calculated Rayleigh-wave phase velocities from vertical component of ambient seismic noise for several years. Recently, researchers started to extract Love waves from transverse component recordings of ambient noise, where "transverse" is defined as the direction perpendicular to a great-circle path or a line in small scale through observation sensors. Most researches assumed Rayleigh waves could be negligible, but Rayleigh waves can exist in the transverse component when Rayleigh waves propagate in other directions besides radial direction. In study of data acquired in western Junggar Basin near Karamay city, China, after processing the transverse component recordings of ambient noise, we obtain two energy trends, which are distinguished with Rayleigh-wave and Love-wave phase velocities, in the frequency-velocity domain using multichannel analysis of surface waves (MASW). Rayleigh waves could be also extracted from the transverse component data. Because Rayleigh-wave and Love-wave phase velocities are close in high frequencies (>0.1 Hz), two kinds of surface waves might be merged in the frequency-velocity domain. Rayleigh-wave phase velocities may be misidentified as Love-wave phase velocities. To get accurate surface-wave phase velocities from the transverse component data using seismic interferometry in investigating the shallow geology, our results suggest using MASW to calculate real Love-wave phase velocities.
Transverse, Propagating Velocity Perturbations in Solar Coronal Loops
De Moortel, I; Wright, A N; Hood, A W
2015-01-01
This short review paper gives an overview of recently observed transverse, propagating velocity perturbations in coronal loops. These ubiquitous perturbations are observed to undergo strong damping as they propagate. Using 3D numerical simulations of footpoint-driven transverse waves propagating in a coronal plasma with a cylindrical density structure, in combination with analytical modelling, it is demonstrated that the observed velocity perturbations can be understood in terms of coupling of different wave modes in the inhomogeneous boundaries of the loops. Mode coupling in the inhomogeneous boundary layers of the loops leads to the coupling of the transversal (kink) mode to the azimuthal (Alfven) mode, observed as the decay of the transverse kink oscillations. Both the numerical and analytical results show the spatial profile of the damped wave has a Gaussian shape to begin with, before switching to exponential decay at large heights. In addition, recent analysis of CoMP (Coronal Multi-channel Polarimeter)...
Longitudinal and transverse velocity fields in parsec-scale jets
Mertens, Florent
2015-01-01
Radio-loud AGN typically manifest powerful relativistic jets extending up to millions of light years and often showing superluminal motions organised in a complex kinematic pattern. A number of physical models are still competing to explain the jet structure and kinematics revealed by radio images using the VLBI technique. Robust measurements of longitudinal and transverse velocity field in the jets would provide crucial information for these models. This is a difficult task, particularly for transversely resolved jets in objects like 3C 273 and M87. To address this task, we have developed a new technique for identifying significant structural patterns (SSP) of smooth, transversely resolved flows and obtaining a velocity field from cross-correlation of these regions in multi-epoch observations. Detection of individual SSP is performed using the wavelet decomposition and multiscale segmentation of the observed structure. The cross-correlation algorithm combines structural information on different scales of the...
Transverse Oscillation Vector Velocity Estimation using a Phased Array Transducer
DEFF Research Database (Denmark)
Marcher, Jønne; Pihl, Michael Johannes; Seerup, Gert;
2012-01-01
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 transduc...... 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....
Measuring 3D Velocity Vectors using the Transverse Oscillation Method
DEFF Research Database (Denmark)
Pihl, Michael Johannes; Jensen, Jørgen Arendt
Experimentally obtained estimates of threedimensional (3D) velocity vectors using the 3D Transverse Oscillation (TO) method are presented. The method employs a 2D transducer and synthesizes two double-oscillating fields in receive to obtain the axial, transverse, and elevation velocity components....... Velocity measurements are conducted in an experimental flow-rig with steady flow in two different directions (mainly in x or y direction). Velocity estimates are obtained along the z axis. All three velocity components (vx, vy, vz) are measured with relative biases and standard deviations (normalized to...... expected value) below 5% and 12%, respectively. For an expected velocity magnitude of 25.2 cm/s, the method estimates 24.4±3.1 cm/s and 25.1±1.9 cm/s for the two directions. Under similar conditions, Field II simulations yield 25.1±1.5 cm/s and 25.4±1.6 cm/s. The experimental results validate the results...
Experimental investigation of transverse velocity estimation using cross-correlation
DEFF Research Database (Denmark)
Bjerngaard, Rasmus; Jensen, Jørgen Arendt
2001-01-01
.23 m/s. The volume flow was determined by a Danfoss MAG 1100 flow meter. The velocity profiles were measured for different beam-to-flow angles of 90, 65, and 45 degrees. A Harming apodized beam focused at the vessel was transmitted using 64 elements and the received signals on all elements were sampled......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...... direction to produce signals that are influenced by the shift of the scatterer's position. The signals are then cross-correllated to find the shift in position and thereby the velocity. The performance of the method is investigated using both a flow phantom and in-vivo measurements. A flow phantom capable...
Phased-array vector velocity estimation using transverse oscillations
DEFF Research Database (Denmark)
Pihl, Michael Johannes; Marcher, Jønne; Jensen, Jørgen Arendt
2012-01-01
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......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....... Therefore, three performance metrics are proposed. They are calculated based on the complex TO spectrum of the combined TO fields. It is hypothesized that the performance metrics are related to the performance of the velocity estimates. The simulations show that the squared correlation values range from 0...
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 by the...... measurements were performed with a commercial ultrasound scanner (BK 3000, BK Ultrasound, Herlev Denmark) and a convex probe (BK ultrasound 6C2, Herlev, Denmark). Ten healthy volunteers were scanned, and recordings of the portal flow during 3-5 heartbeats were conducted with an intercostal and subcostal view...
Using Phased Array for Transverse Oscillation Vector Velocity Imaging
DEFF Research Database (Denmark)
Pihl, Michael Johannes; Haugaard, Per; Jensen, Jørgen Arendt
be expanded to phased arrays enabling vector velocity imaging of the heart. Therefore, the performance of the TO estimator has to be evaluated for depths up to 10-15 cm. Methods The TO method is based on creating a double oscillating field. Flow phantoms were simulated with a transverse (90º) parabolic flow...... profile (peak = 1 m/s) and a vessel radius of 5 mm, and ‘scanned’ orthogonal to the flow with a 3.5 MHz phased array transducer. The performance of the lateral velocity estimates were evaluated by calculating the relative mean bias, Br, and relative mean standard deviation, σr, inside the vessel of N=20...
Seeding of ambient electrons in critical velocity ionization
International Nuclear Information System (INIS)
Despite repeated demonstration of high ionization efficiencies in critical ionization velocity (CIV) experiments in the laboratory, much lower efficiencies have been reported in space CIV experiments. A survey of the CIV experiments in space reveals that higher ambient electron density appears to favor ionization. The authors discuss some theoretical reasons on the density correlation. Since the natural ambient electron density in the ionosphere is limited, the authors propose an experiment in which electrons are seeded artifically to form a high electron density region through which a neutral beam is injected with a velocity above its critical ionization velocity
Robust seismic velocity change estimation using ambient noise recordings
Daskalakis, E; Garnier, J; Melis, N S; Papanicolaou, G; Tsogka, C
2016-01-01
We consider the problem of seismic velocity change estimation using ambient noise recordings. Motivated by [23] we study how the velocity change estimation is affected by seasonal fluctuations in the noise sources. More precisely, we consider a numerical model and introduce spatio-temporal seasonal fluctuations in the noise sources. We show that indeed, as pointed out in [23], the stretching method is affected by these fluctuations and produces misleading apparent velocity variations which reduce dramatically the signal to noise ratio of the method. We also show that these apparent velocity variations can be eliminated by an adequate normalization of the cross-correlation functions. Theoretically we expect our approach to work as long as the seasonal fluctuations in the noise sources are uniform, an assumption which holds for closely located seismic stations. We illustrate with numerical simulations and real measurements that the proposed normalization significantly improves the accuracy of the velocity chang...
Shear velocity of the Rotokawa geothermal field using ambient noise
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.
Robust seismic velocity change estimation using ambient noise recordings
Daskalakis, E.; Evangelidis, C. P.; Garnier, J.; Melis, N. S.; Papanicolaou, G.; Tsogka, C.
2016-06-01
We consider the problem of seismic velocity change estimation using ambient noise recordings. Motivated by Zhan et al., we study how the velocity change estimation is affected by seasonal fluctuations in the noise sources. More precisely, we consider a numerical model and introduce spatio-temporal seasonal fluctuations in the noise sources. We show that indeed, as pointed out by Zhan et al., the stretching method is affected by these fluctuations and produces misleading apparent velocity variations which reduce dramatically the signal to noise ratio of the method. We also show that these apparent velocity variations can be eliminated by an adequate normalization of the cross-correlation functions. Theoretically we expect our approach to work as long as the seasonal fluctuations in the noise sources are uniform, an assumption which holds for closely located seismic stations. We illustrate with numerical simulations in homogeneous and scattering media that the proposed normalization significantly improves the accuracy of the velocity change estimation. Similar behaviour is also observed with real data recorded in the Aegean volcanic arc. We study in particular the volcano of Santorini during the seismic unrest of 2011-2012 and observe a decrease in the velocity of seismic waves which is correlated with GPS measured elevation.
International Nuclear Information System (INIS)
A multi-dimensional electron phase-space hole (electron hole) is considered to be unstable to the transverse instability. We perform two-dimensional (2D) particle-in-cell (PIC) simulations to study the evolutions of electron holes in weakly magnetized plasma (Ωe pe, where Ωe and ωpe are the electron gyrofrequency and plasma frequency, respectively), and the effects of perpendicular thermal velocities on the transverse instability are investigated. The transverse instability can cause decay of the electron holes. We find that with the increasing perpendicular thermal velocity tending to stabilize the transverse instability, the corresponding wave numbers decrease
Transverse Oscillations for Phased Array Vector Velocity Imaging
DEFF Research Database (Denmark)
Pihl, Michael Johannes; Jensen, Jørgen Arendt
(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....... receive to obtain lateral spatial in-phase and quadrature components. The relative mean bias and standard deviation of the lateral velocity component are computed as performance measures. For the PEF, the coefficient of variance, CV, of the spectral frequencies, and the energy ratio, ER, of leakage into...
Data adaptive estimation of transversal blood flow velocities
DEFF Research Database (Denmark)
Pirnia, E.; Jakobsson, A.; Gudmundson, E.; Jensen, Jørgen Arendt
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...
International Nuclear Information System (INIS)
Using a 2-D simulation model, the spreading of a passive solute is investigated varying the transversal distribution assumed for the diffusion coefficient and the velocity. Using strongly different laws, the simulation results show a larger influence on the dispersion process by the velocity distribution, while the influence of the diffusion coefficient distribution is very small, so that it is important just to catch the average value for this coefficient. Different transversal distributions of velocity produce values of maximum concentration with a scatter in the 30-40% range
Improved Vector Velocity Estimation using Directional Transverse Oscillation
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt
2015-01-01
8820e transducer with a focal point at 105.6 mm (F#=5) for Vector Flow Imaging (VFI). A 6 mm radius tube in a circulating flow rig was scanned and the parabolic volume flow of 112.7 l/h (peak velocity 0.55 m/s) measured by a Danfoss Magnetic flow meter for reference. Velocity estimates for DTO are...... found for 32 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...
Precision measurement of transverse velocity distribution of a strontium atomic beam
F. Gao; Liu, H.; P. Xu; Tian, X.; Y Wang; Ren, J; Haibin Wu; Hong Chang
2014-01-01
We measure the transverse velocity distribution in a thermal Sr atomic beam precisely by velocity-selective saturated fluorescence spectroscopy. The use of an ultrastable laser system and the narrow intercombination transition line of Sr atoms mean that the resolution of the measured velocity can reach 0.13 m/s, corresponding to 90$\\mu K$ in energy units. The experimental results are in very good agreement with the results of theoretical calculations. Based on the spectroscopic techniques use...
Institute of Scientific and Technical Information of China (English)
WU Ming-Yu; WU Hong; LU Quan-Ming; XUE Bing-Sen
2010-01-01
@@ A multi-dimensional electron phase-space hole(electron hole)is considered to be unstable to the transverse instability.We perform two-dimensional(219)particle-in-cell(PIC)simulations to study the evolutions of electron holes in weakly magnetized plasma(Ωe < ωpe,where Ωe and ωpe are the electron gyrofrequency and plasma frequency,respectively),and the effects of perpendicular thermal velocities on the transverse instability are investigated.
Magnetic domain-wall velocity enhancement induced by a transverse magnetic field
Yang, Jusang; Beach, Geoffrey S. D.; Knutson, Carl; Erskine, James L.
2016-01-01
Spin dynamics of field-driven domain walls (DWs) guided by permalloy nanowires are studied by high-speed magneto-optic polarimetry and numerical simulations. DW velocities and spin configurations are determined as functions of longitudinal drive field, transverse bias field, and nanowire width. Nanowires having cross-sectional dimensions large enough to support vortex wall structures exhibit regions of drive-field strength (at zero bias field) that have enhanced DW velocity resulting from coupled vortex structures that suppress oscillatory motion. Factor of 10 enhancements of the DW velocity are observed above the critical longitudinal drive-field (that marks the onset of oscillatory DW motion) when a transverse bias field is applied. Nanowires having smaller cross-sectional dimensions that support transverse wall structures also exhibit a region of higher mobility above the critical field, and similar transverse-field induced velocity enhancement but with a smaller enhancement factor. The bias-field enhancement of DW velocity is explained by numerical simulations of the spin distribution and dynamics within the propagating DW that reveal dynamic stabilization of coupled vortex structures and suppression of oscillatory motion in the nanowire conduit resulting in uniform DW motion at high speed. The enhanced velocity and drive field range are achieved at the expense of a less compact DW spin distribution.
Magnetic domain-wall velocity enhancement induced by a transverse magnetic field
Yang, Jusang; Beach, Geoffrey S. D.; Knutson, Carl; Erskine, James L.
2011-01-01
Spin dynamics of field-driven domain walls (DWs) guided by Permalloy nanowires are studied by high-speed magneto-optic polarimetry and numerical simulations. DW velocities and spin configurations are determined as functions of longitudinal drive field, transverse bias field, and nanowire width. Nanowires having cross-sectional dimensions large enough to support vortex wall structures exhibit regions of drive-field strength (at zero bias field) that have enhanced DW velocity resulting from cou...
Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per; Hansen, Jens Munk; Hansen, Kristoffer Lindskov; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt
2011-01-01
Spectral velocity estimation is considered the gold standard in medical ultrasound. Peak systole (PS), end diastole (ED), and resistive index (RI) are used clinically. Angle correction is performed using a flow angle set manually. With Transverse Oscillation (TO) velocity estimates the flow angle, peak systole (PSTO), end diastole (EDTO), and resistive index (RITO) are estimated. This study investigates if these clinical parameters are estimated equally good using spectral and TO data. The ri...
Yang, Ya-Ting; Yoshida, Yasuyuki; Hortobagyi, Tibor; Suzuki, Shuji
2013-01-01
We determined the angular range of motion and the relative timing of displacement in the thorax, lumbar spine, and pelvis in the transverse plane during treadmill walking at three velocities. Nine healthy young females walked on a treadmill for three minutes at 0.40, 0.93, and 1.47 m/s. The position
New Developments in Vector Velocity Imaging using the Transverse Oscillation Approach
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt; Pihl, Michael Johannes; Olesen, Jacob Bjerring; Møller Hansen, Peter; Lindskov Hansen, Kristoffer; Bachmann Nielsen, Michael
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...... examples from venous flow to rotational flow in the heart will be shown. The technique is also being further developed and adapted for convex and phased array probes, for spectral velocity estimation, pressure estimation, and for three dimensional velocity tensor imaging. It is shown how the methods are...... optimized using Field II simulations along with several examples of their performance....
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...... for TO estimation was 7.0% at a beam-to-flow angle of 75. This was 3.8% for directional beamforming and at 60 it was 2.2%. The general improvement, however, comes at an increase by a factor of roughly 11 in the number of calculations for the directional beamformation compared to the TO method....
Precision measurement of transverse velocity distribution of a Strontium atomic beam
Gao, F; Xu, P; Tian, X; Wang, Y; Ren, J; Wu, Haibin; Chang, Hong
2013-01-01
We measure precisely the transverse velocity distribution in a thermal Sr atomic beam with a velocity selective saturated fluorescence spectroscopy. By using the ultrastable laser system and narrow intercombination transition line of Sr atoms, the resolution of the velocity measured can be reached 0.13m/s, corresponding to 90$\\mu K$ in energy unit. The experimental results are agreement very well with a theoretical calculation. With the spectroscopic techniques, the absolute frequency of the intercombination transition of $^{88}$Sr is measured by an optical-frequency comb generator referenced to the SI second through an H maser, which is given by 434 829 121 318(10)kHz.
DEFF Research Database (Denmark)
Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev;
2014-01-01
, 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...
International Nuclear Information System (INIS)
New method of calculation of conditional and complete averages of transverse velocity in intermittent turbulent flows is proposed. Comparison between the results of experiments and calculations of transverse velocity and axial-symmetric jet, in the trail down steam the round cylinder and in the external area of wall boundary layer showed close fit. (author)
Leveque, Emmanuel
2014-01-01
Based on geometric considerations, longitudinal and transverse Lagrangian velocity increments are introduced as components along, and perpendicular to, the displacement of fluid particles during a time scale {\\tau}. It is argued that these two increments probe preferentially the stretching and spinning of material fluid elements, respectively. This property is confirmed (in the limit of vanishing {\\tau}) by examining the variances of these increments conditioned on the local topology of the flow. Interestingly, these longitudinal and transverse Lagrangian increments are found to share some qualitative features with their Eulerian counterparts. In particular, direct numerical simulations at turbulent Reynolds number up to 300 show that the distributions of the longitudinal increment are negatively skewed at all {\\tau}, which is a signature of time irreversibility of turbulence in the Lagrangian framework. Transverse increments are found more intermittent than longitudinal increments, as quantified by the compa...
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...
DNS of velocity and thermal fields in turbulent channel flow with transverse-rib roughness
International Nuclear Information System (INIS)
A detailed knowledge of both velocity and thermal fields in wall turbulence disturbed by a row of ribs on the wall is important for clarifying the chief factors of fluid and thermal dynamics related to the control of heat transfer. In this study, in order to elucidate the effects of roughness on the statistical quantities in the velocity and thermal fields, direct numerical simulations (DNS) of heat transfer in turbulent channel flows with transverse-rib roughness have been performed by varying their spacing, width and height, in which the turbulent heat transfer with k-type and d-type roughness walls are simulated. It is found that since turbulent mixing is promoted by arranging ribs, the distributions of mean velocity and temperature become markedly asymmetric. Systematic variations of secondary flow patterns between ribs are clearly identified. The best heat transfer performance is found to be obtained with the k-type roughness
Precision measurement of transverse velocity distribution of a strontium atomic beam
Directory of Open Access Journals (Sweden)
F. Gao
2014-02-01
Full Text Available We measure the transverse velocity distribution in a thermal Sr atomic beam precisely by velocity-selective saturated fluorescence spectroscopy. The use of an ultrastable laser system and the narrow intercombination transition line of Sr atoms mean that the resolution of the measured velocity can reach 0.13 m/s, corresponding to 90 μK in energy units. The experimental results are in very good agreement with the results of theoretical calculations. Based on the spectroscopic techniques used here, the absolute frequency of the intercombination transition of 88Sr is measured using an optical-frequency comb generator referenced to the SI second through an H maser, and is given as 434 829 121 318(10 kHz.
Precision measurement of transverse velocity distribution of a strontium atomic beam
Energy Technology Data Exchange (ETDEWEB)
Gao, F.; Liu, H.; Tian, X. [CAS Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Xi' an 710600 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xu, P.; Wang, Y.; Ren, J. [CAS Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Xi' an 710600 (China); Wu, Haibin, E-mail: hbwu@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062 (China); Chang, Hong, E-mail: changhong@ntsc.ac.cn [CAS Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Xi' an 710600 (China); State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062 (China)
2014-02-15
We measure the transverse velocity distribution in a thermal Sr atomic beam precisely by velocity-selective saturated fluorescence spectroscopy. The use of an ultrastable laser system and the narrow intercombination transition line of Sr atoms mean that the resolution of the measured velocity can reach 0.13 m/s, corresponding to 90 μK in energy units. The experimental results are in very good agreement with the results of theoretical calculations. Based on the spectroscopic techniques used here, the absolute frequency of the intercombination transition of {sup 88}Sr is measured using an optical-frequency comb generator referenced to the SI second through an H maser, and is given as 434 829 121 318(10) kHz.
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
A method for obtaining vector flow images using the transverse oscillation (TO) approach on a convex array is presented. The paper presents optimization schemes for TO fields and evaluates their performance using simulations and measurements with an experimental scanner. A 3-MHz 192-element convex...... 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...
The Transverse velocity of the Andromeda system, derived from the M31 satellite population
Salomon, J -B; Famaey, B; Martin, N F; Lewis, G F
2015-01-01
We present a dynamical measurement of the tangential motion of the Andromeda system, the ensemble consisting of the Andromeda Galaxy (M31) and its satellites. The system is modelled as a structure with cosmologically-motivated velocity dispersion and density profiles, and we show that our method works well when tested using the most massive substructures in high-resolution {\\Lambda} Cold Dark Matter ({\\Lambda}CDM) simulations. Applied to the sample of 40 currently-known galaxies of this system, we find a value for the transverse velocity of 164.4 +/- 61.8 km/s (v_{East} = -111.5 +/- 70.2 km/s and v{North} = 99.4 +/- 60.0 km/s), significantly higher than previous estimates of the proper motion of M31 itself. This result has significant implications on estimates of the mass of the Local Group, as well as on its past and future history.
Hayashida, T.; Yoshimi, M.; Horikawa, H.
2014-12-01
We have applied seismic interferometry to three-component ambient noise data recorded around the Ise bay area, central Japan, to validate published three-dimensional S-wave velocity models. For the bay area, detailed seismic velocity structure models have been constructed based on P-wave reflection surveys. There is no direct information on the S-wave velocities beneath the bay and the parameters are assigned by reference to those in a land area. We used one-year continuous data from 20 permanent stations of the NIED Hi-net (High-sensitivity seismograph network) to obtain stacked cross-correlation functions (CCFs) of ambient noise between station pairs that cross the bay. The CCFs were calculated, using one-hour data in the radial-radial (R-R), transverse-transverse (T-T) and vertical-vertical (Z-Z) directions for time lags of ±500s. Horizontal distances between the stations range form 15 km to 103 km. Although the Hi-net stations deploy seismometers with the natural period of 1 s, we found that the yearly stacked CCFs for selected 101 Hi-net station pairs are comparable with those derived from neighboring broadband seismic stations in the frequency range between 0.1 and 0.5 Hz, by deconvolving the instrument response. The CCFs shows clear Rayleigh waves from all directions in the R-R and Z-Z components, and clear Love waves in the T-T component with reasonable signal-to-noise ratios. The derived group velocities and waveforms of the wave trains are variable in the higher frequency range (> 0.2 Hz), indicating deep sedimentary basin beneath the bay. We compared obtained group velocities with theoretical ones to find systematic differences between the expected structure model from the CCFs and the published models in the northwest part of the bay, while the agreements are generally good for many other station pairs. This result indicates that the seismic interferometry technique provides valuable information for validation and improvement of a velocity structure
International Nuclear Information System (INIS)
We propose a parameter-free method to determine the temperature of a thermalized state in relativistic nuclear interactions, using the experimental μq/T and μs/T values, obtained from strange particle ratios. The hadron gas formalism and strangeness neutrality are employed to relate the quark-chemical potential μq and μs to the temperature and thus determine its value at chemical freeze-out. This temperature, together with the inverse slope parameter from mT distributions, enable the determination of the transverse flow velocity of the fireball matter, thus disentangling the thermal and flow effects. We study several nucleus-nucleus interactions from AGS and SPS and obtain the temperature, transverse flow velocity, and quark-chemical potentials. Extrapolating the systematics we predict the values of these quantities for ongoing and future experiments at AGS, SPS, and RHIC. We discuss the possibility of reaching the conditions for quark deconfinement and QGP formation and give distinct and identifiable signature. copyright 1996 The American Physical Society
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 is invest......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...... - tions cover the positive octant of the unit sphere. In terms of accuracy, the median bias is −2%. The precision of v x and v y depends on the flow angle β and ranges from 5% to 31% rela - tive to the peak velocity magnitude of 1 m/s. For comparison, the range is 0.4 to 2% for v z . The parameter study...
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.
:,; Barbeau, P S; Beck, D; Belov, V; Breidenbach, M; Brunner, T; Burenkov, A; Cao, G F; Cen, W R; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Danilov, M; Daugherty, S J; Daughhetee, J; Davis, J; Delaquis, S; Der Mesrobian-Kabakian, A; DeVoe, R; Didberidze, T; Dilling, J; Dolgolenko, A; Dolinski, M J; Dunford, M; Fairbank, W; Farine, J; Feyzbakhsh, S; Fierlinger, P; Fudenberg, D; Gornea, R; Graham, K; Gratta, G; Hall, C; Hughes, M; Jewell, M J; Johnson, A; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Kravitz, S; Krucken, R; Kuchenkov, A; Kumar, K S; Lan, Y; Leonard, D S; Licciardi, C; Lin, Y H; MacLellan, R; Marino, M G; Mong, B; Moore, D; Njoya, O; Nelson, R; Odian, A; Ostrovskiy, I; Piepke, A; Pocar, A; Prescott, C Y; Retiere, F; Rowson, P C; Russell, J J; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Tsang, R; Twelker, K; Vuilleumier, J -L; Waite, A; Walton, J; Walton, T; Weber, M; Wen, L J; Wichoski, U; Wood, J; Yang, L; Yen, Y -R; Zeldovich, O Ya; Zettlemoyer, J
2016-01-01
The EXO-200 Collaboration is searching for neutrinoless double beta decay using a liquid xenon (LXe) time projection chamber. This measurement relies on modeling the transport of charge deposits produced by interactions in the LXe to allow discrimination between signal and background events. Here we present measurements of the transverse diffusion constant and drift velocity of electrons at drift fields between 20~V/cm and 615~V/cm using EXO-200 data. At the operating field of 380~V/cm EXO-200 measures a drift velocity of 1.705$_{-0.010}^{+0.014}$~mm/$\\mu$s and a transverse diffusion coefficient of 55$\\pm$4~cm$^2$/s.
Directory of Open Access Journals (Sweden)
Roque Leal Salcedo
2008-01-01
Full Text Available El derecho internacional ambiental es un conocimiento de carácter transversal, que entre otras consideraciones refleja las preocupaciones de la sociedad por la implementación de un modelo de desarrollo sustentable para el respeto a las reglas del medio natural que garantizan la integridad y renovación de los sistemas naturales. El presente artículo enfoca esta visión a través del análisis de material documental revisado, entre ellos tratados internacionales que permiten distinguir el desarrollo del derecho internacional ambiental y el papel de Organización de las Naciones Unidas (ONU, en el propósito común del derecho individual y colectivo de disfrutar de una vida, un ambiente seguro, sano y ecológicamente equilibrado. En función a estas disertaciones las consideraciones finales exponen parte de la visión que ha estructurado la ONU y que representan un aporte considerable en el fomento de la conciencia mundial sobre la necesidad de establecer vínculos entre las naciones para el continuo desarrollo de esta rama del derecho.
Spatial coherences of the sound pressure and the particle velocity in underwater ambient noise
Institute of Scientific and Technical Information of China (English)
YAN Jin; LUO Xianzhi; HOU Chaohuan
2007-01-01
The spatial coherences were investigated between the sound pressure and the three orthogonal components of the particle velocity in underwater ambient noise. Based on the ray theory, integral expression was derived for the spatial coherence matrix of the sound pressure and the particle velocity in a stratified ocean with dipole noise sources homogenously distributed on the surface. The integrand includes a multiplying factor of the vertical directivity of the noise intensity, and the layered ocean environment affects the spatial coherences via this directivity factor. For a shallow water environment and a semi-infinite homogenous medium, the coherence calculation results were given. It was showed that the sound speed profile and the sea bottom could not be neglected in determining the spatial coherences of the ambient noise vector field.
SPATIAL VARIABILTY OF AMBIENT TEMPERATURE, RELATIVE HUMIDITY AND AIR VELOCITY IN A COLD STORE
SERAP AKDEMIR; SELCUK ARIN
2006-01-01
Spatial distribution the ambient temperature, relative humidity and air velocity were determined for different storage temperatures such as 0 oC, 1 oC, 2 oC and 3 oC in an experimental cold store. Mapping software were used to show the variability. Spatial distribution of the temperature and the relative humidity was not uniform in the cold store. Reason of bad spatial distributions was bad spatial distribution of air velocity distributed by evaporator. A temperature and/or a relative humi...
On measuring surface wave phase velocity from station-station cross-correlation of ambient signal
Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie; Ekström, Göran; Zunino, Andrea; Giardini, Domenico
2013-01-01
International audience We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one method involves the time-domain cross-correlation of signal recorded at different stations; the other is based on frequency-domain cross-correlation, and requires finding the ze...
High resolution Rayleigh wave group velocity tomography in North-China from ambient seismic noise
International Nuclear Information System (INIS)
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)
Crustal velocity structure of Central and Eastern Turkey from ambient noise tomography
Warren, Linda M.; Beck, Susan L.; Biryol, C. Berk; Zandt, George; Özacar, A. Arda; Yang, Yingjie
2013-09-01
In eastern Turkey, the ongoing convergence of the Arabian and African plates with Eurasia has resulted in the westward extrusion of the Anatolian Plate. To better understand the current state and the tectonic history of this region, we image crust and uppermost mantle structure with ambient noise tomography. Our study area extends from longitudes of 32° to 44°E. We use continuous data from two temporary seismic deployments, our 2006-2008 North Anatolian Fault Passive Seismic Experiment and the 1999-2001 Eastern Turkey Seismic Experiment, as well as from additional seismographs in the region. We compute daily cross-correlations of noise records between all station pairs and stack them over the entire time period for which they are available, as well as in seasonal subsets, to obtain interstation empirical Green's functions. After selecting interstation cross-correlations with high signal-to-noise ratios and measuring interstation phase velocities, we compute phase velocity maps at periods ranging from 8 to 40 s. At all periods, the phase velocity maps are similar for winter and summer subsets of the data, indicating that seasonal variations in noise sources do not bias our results. Across the study area, we invert the phase velocity estimates for shear velocity as a function of depth. The shear velocity model, which extends to 50 km depth, highlights tectonic features apparent at the surface: the Eastern Anatolian Plateau is a prominent low-velocity anomaly whereas the Kirşehir Massif has relatively fast velocities. There is a large velocity jump across the Inner Tauride Suture/Central Anataolian Fault Zone throughout the crust whereas the North Anatolian Fault does not have a consistent signature. In addition, in the southeastern part of our study area, we image a high velocity region below 20 km depth which may be the northern tip of the underthrusting Arabian Plate.
Mediavilla, E; Munoz, J A; Battaner, E
2016-01-01
We propose to use the flux variability of lensed quasar images induced by gravitational microlensing to measure the transverse peculiar velocity of lens galaxies over a wide range of redshift. Microlensing variability is caused by the motions of the observer, the lens galaxy (including the motion of the stars within the galaxy), and the source; hence, its frequency is directly related to the galaxy's transverse peculiar velocity. The idea is to count time-event rates (e.g., peak or caustic crossing rates) in the observed microlensing light curves of lensed quasars that can be compared with model predictions for different values of the transverse peculiar velocity. To compensate for the large time-scale of microlensing variability we propose to count and model the number of events in an ensemble of gravitational lenses. We develop the methodology to achieve this goal and apply it to an ensemble of 17 lensed quasar systems. In spite of the shortcomings of the available data, we have obtained tentative estimates...
McKee, K. F.; Waite, G. P.; Richardson, J. P.
2012-12-01
We used the Green's functions from auto-correlations and cross-correlations of seismic ambient noise to monitor temporal velocity changes in the subsurface at Villarrica Volcano in the Southern Andes of Chile. Campaigns were conducted from March to October 2010 and February to April 2011 with 8 broadband and 6 short-period stations, respectively. We prepared the data by removing the instrument response, normalizing with a root-mean-square method, whitening the spectra, and filtering from 1 to 10 Hz. This frequency band was chosen based on the relatively high background noise level in that range. Hour-long auto- and cross-correlations were computed and the Green's functions stacked by day and total time. To track the temporal velocity changes we stretched a 24 hour moving window of correlation functions from 90% to 110% of the original and cross correlated them with the total stack. The average increase in velocity gleaned from the auto-correlations during the 2010 array was 0.13%, as seen in the figure. Cross-correlations from station V01, near the summit, to the other stations show comparable increases in velocity. We attribute this change to the closing of cracks in the subsurface due either to seasonal snow loading or regional tectonics. In addition to the common increase in velocity across the stations, there are excursions in velocity on the same order lasting several days. Amplitude decreases as the station's distance from the vent increases suggesting these excursions may be attributed to changes within the volcanic edifice. Two occurrences are highlighted in the figure in which it is seen that the amplitudes at stations V06 and V07, the stations farthest from the vent, are smaller. Similar short temporal excursions were seen in the auto-correlations from 2011, however, there was little to no increase in the overall velocity.ercent change in velocity at Villarrica Volcano, Chile from March to October 2010 (stations offset by 0.2%)
International Nuclear Information System (INIS)
Analytical solution of transverse shear strain vibration of a tube caused by internal gaseous detonation near the second critical speed (shear group velocity) is not reported in the literature. It is performed based on a steady state model and first order shear deformation theories (model I and II) in this paper, and the results are verified through comparison with the finite element results reported in the literature. There are no known experimental ways of directly measuring dynamic transverse shear strain and only theoretical results and numerical data are available. The finite element method is very time consuming compared with the analytical solution. It is shown in this paper that the resonance phenomenon of the transverse shear strain vibration near the second critical speed can be predicted by steady state model and first order shear deformation theories. The first order shear deformation theory (model II) has a good agreement with finite element results in prediction of dynamic amplification factors and critical speeds.
Borges, J. F.; Silva, H. G.; Torres, R. J. G.; Caldeira, B.; Bezzeghoud, M.; Furtado, J. A.; Carvalho, J.
2016-07-01
During its history, several significant earthquakes have shaken the Lower Tagus Valley (Portugal). These earthquakes were destructive; some strong earthquakes were produced by large ruptures in offshore structures located southwest of the Portuguese coastline, and other moderate earthquakes were produced by local faults. In recent years, several studies have successfully obtained strong-ground motion syntheses for the Lower Tagus Valley using the finite difference method. To confirm the velocity model of this sedimentary basin obtained from geophysical and geological data, we analysed the ambient seismic noise measurements by applying the horizontal to vertical spectral ratio (HVSR) method. This study reveals the dependence of the frequency and amplitude of the low-frequency (HVSR) peaks (0.2-2 Hz) on the sediment thickness. We have obtained the depth of the Cenozoic basement along a profile transversal to the basin by the inversion of these ratios, imposing constraints from seismic reflection, boreholes, seismic sounding and gravimetric and magnetic potentials. This technique enables us to improve the existing three-dimensional model of the Lower Tagus Valley structure. The improved model will be decisive for the improvement of strong motion predictions in the earthquake hazard analysis of this highly populated basin. The methodology discussed can be applied to any other sedimentary basin.
Ueli, Meier; Brenguier, Florent; M. Shapiro, N.
2010-01-01
International audience We analyze 3 years of continuous seismic records from broadband stations of the Caltech Regional Seismic Network (CI) in vicinity of the Los Angeles basin. Using correlations of ambient seismic noise, relative velocity variations in the order of 0.1 % can be measured between all inter-station pairs. It is the first time that such an extensive study between 861 inter-station pairs over such a large area has been carried out. We perform these measurements using the 'st...
SPATIAL VARIABILTY OF AMBIENT TEMPERATURE, RELATIVE HUMIDITY AND AIR VELOCITY IN A COLD STORE
Directory of Open Access Journals (Sweden)
SERAP AKDEMIR
2006-10-01
Full Text Available Spatial distribution the ambient temperature, relative humidity and air velocity were determined for different storage temperatures such as 0 oC, 1 oC, 2 oC and 3 oC in an experimental cold store. Mapping software were used to show the variability. Spatial distribution of the temperature and the relative humidity was not uniform in the cold store. Reason of bad spatial distributions was bad spatial distribution of air velocity distributed by evaporator. A temperature and/or a relative humidity sensor are used in cooling systems to measure temperature and relative humidity. The umber of sensors are not enough to determine variability of temperature and relative humidity. There should be additional sensors located different places to give idea for cold storage.
MSNoise: a Python Package for Monitoring Seismic Velocity Changes using Ambient Seismic Noise
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
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.
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.
Hasan Alfaisal
2011-01-01
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, wh...
International Nuclear Information System (INIS)
The objective of ultrarelativistic heavy ions collisions is to produce an energy density and a temperature in the region of overlap between two colliding ions, that is high enough so that the quarks, initially confined in hadrons, can move freely. The study of this phase transition between quark-gluon plasma and hadron plasma provides information about the Universe evolution. The present cosmological theories consider that, in the early Universe such state of deconfined quarks and gluons existed, a few microseconds after Big Bang. At RHIC (Relativistic Heavy Ions Collider) - BNL (Brookhaven National Laboratory), the BRAHMS (Broad RAnge Hadron Magnetic Spectrometers) measured hadron spectra from Au-Au collisions at 200 AGeV. >From charged pions, kaons, protons and antiprotons transverse mass spectra we determine the effective temperatures and particles yields.The mass dependence of the effective temperatures provides evidence of collective transverse flow of the nuclear matter formed in these collisions. We deduce the velocity of the collective transverse expansion of hadrons produced in these collisions until they freeze-out at a temperature Tfo. We study the flow velocity and the freeze-out temperature dependence of centrality of the collisions for charged pions, kaons, protons and antiprotons. (authors)
International Nuclear Information System (INIS)
In this experiment we studied the possibility of producing a pulsed beam for greater instantaneous beam flux, cooling the beam transversely to increase the effective beam flux and finally optical pumping to produce spin polarized atomic beam. We successfully and reliably produced a pulsed beam, and observed definite transverse cooling of the beam. We developed rather elaborate control program and interface hardware to produce the pulsed beam, and transversely cool, optically pump, and detect the atoms. We have produced the low-velocity intense source(LVIS) beam and operated it in a pulsed mode. Using an electronically controlled shutter we could load a Magneto Optical Trap(MOT) for 1 sec and launched a pulse of rubidium atoms. We performed the transverse cooling experiment using the pulses. In order to detect how the cooling is working, we used a slit to narrow down the probe beam. The probe beam had a width of 1 mm and we scanned it using a micrometer-controlled translational stage. (Cho, G.S.). 7 refs., 2 figs
Efficient focusing scheme for transverse velocity estimation using cross-correlation
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt
2001-01-01
The blood velocity can be estimated by cross-correlation of received RE signals, but only the velocity component along the beam direction is found. A previous paper showed that the complete velocity vector can be estimated, if received signals are focused along lines parallel to the direction 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...
On measuring surface wave phase velocity from station–station cross-correlation of ambient signal
DEFF Research Database (Denmark)
Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie;
2012-01-01
We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one...... method involves the time-domain cross-correlation of signal recorded at different stations; the other is based on frequency-domain cross-correlation, and requires finding the zero-crossings of the real part of the cross-correlation spectrum. Furthermore, the time-domain method, as implemented here and in...... the literature, practically involves the important approximation that interstation distance be large compared to seismic wavelength. In both cases, cross-correlations are ensemble-averaged over a relatively long period of time (1 yr). We verify that the two algorithms give consistent results, and...
Eje transversal ambiental en el Instituto Tecnológico de Costa Rica
Directory of Open Access Journals (Sweden)
Miriam Brenes
2008-05-01
Full Text Available Este artículo es el resumen de una las actividades realizadas en el proyecto “Introducción de la Dimensión Ambiental (IDA en el currículo del Instituto Tecnológico de Costa Rica (ITCR, elproyecto se desarrolló con recursos de la Vicerrectoría de Docencia en el año 2005-2006. Los resultados obtenidos que se presentan son de una encuesta aplicada a todos los docentes de la institución en el Campus Central de Cartago y el Centro Académico en San José en el año 2005. En total fueron 281 docentes universitarios.
Highly transverse velocity distribution of convoy electrons emitted by highly charged ions
Seliger, M.; Tőkési, K.; Reinhold, C. O.; Burgdörfer, J.
2003-05-01
We present a theoretical study of convoy electron emission resulting from highly charged ion (HCI) transport through carbon foils. Employing a classical transport theory we analyze the angular and energy distribution formed by multiple scattering of electrons in the solid. We find that the convoy electron distribution becomes highly transverse at intermediate foil thicknesses representing an oblate spheroidal distribution due to the stepwise excitation of the HCI. The calculated convoy electron spectra are found to be in good agreement with recent measurements.
Suzuki, Y.
2016-05-01
This article demonstrates the practical applicability of a method of modelling shape memory alloys (SMAs) as actuators. For this study, a pair of SMA wires was installed in an antagonistic manner to form an actuator, and a linear differential equation that describes the behaviour of the actuator’s generated force relative to its input voltage was derived for the limited range below the austenite onset temperature. In this range, hysteresis need not be considered, and the proposed SMA actuator can therefore be practically applied in linear control systems, which is significant because large deformations accompanied by hysteresis do not necessarily occur in most vibration control cases. When specific values of the parameters used in the differential equation were identified experimentally, it became clear that one of the parameters was dependent on ambient airflow velocity. The values of this dependent parameter were obtained using an additional SMA wire as a sensor. In these experiments, while the airflow distribution around the SMA wires was varied by changing the rotational speed of the fans in the wind tunnels, an input voltage was conveyed to the SMA actuator circuit, and the generated force was measured. In this way, the parameter dependent on airflow velocity was estimated in real time, and it was validated that the calculated force was consistent with the measured one.
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...... flow) 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...
Kolínský, Petr; Zigone, Dimitri; Fuchs, Florian; Bianchi, Irene; Qorbani, Ehsan; Apoloner, Maria-Theresia; Bokelmann, Götz; AlpArray-EASI Working Group
2016-04-01
The Eastern Alpine Seismic Investigation (EASI) was a complementary experiment to the AlpArray project. EASI was composed of 55 broadband seismic stations deployed in a winding swath of 540 km length along longitude 13.350 E from the Czech-German border to the Adriatic Sea. Average north-south inter-station distance was 10 km, the distance of each station to either side of the central line was 6 km. Such a dense linear network allows for surface wave dispersion measurements by both deterministic and ambient noise sources along the same paths. During the experiment (July 2014 - August 2015), three earthquakes ML = 2.6, 2.9 and 4.2 occurred in Austria and Northern Italy only several kilometers off the swath. We measure Rayleigh and Love wave group velocities between the source and a single station for the recorded earthquakes, as well as phase velocities between selected pairs of stations using the standard two-station method. We also calculate cross-correlations of ambient noise between selected pairs of stations and we determine the corresponding group velocity dispersion curves. We propose a comparison of phase velocities between two stations measured from earthquakes with group velocities obtained from cross-correlations for the same station pairs. We also compare group velocities measured at single station using earthquakes, which occurred along the swath, with group velocities measured from cross-correlations. That way we analyze velocities of both deterministic and ambient noise reconstructed surface waves propagating along the same path. We invert the resulting dispersion curves for 1D shear wave velocity profiles with depth and we compile a quasi-2D velocity model along the EASI swath.
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......, Open Computing Language (OpenCL) is used to estimate 2-D vector velocity flow in vivo in the carotid artery. Data are streamed live from a BK Medical 2202 Pro Focus UltraView Scanner to a workstation running a research interface software platform. Processing data from a 50 millisecond frame of a duplex...... 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...
Blood flow velocity in the Popliteal Vein using Transverse Oscillation Ultrasound
DEFF Research Database (Denmark)
Bechsgaard, Thor; Lindskov Hansen, Kristoffer; Brandt, Andreas Hjelm; Holbek, Simon; Lönn, Lars; Strandberg, Charlotte; Bækgaard, Niels; Bachmann Nielsen, Michael; Jensen, Jørgen Arendt
2016-01-01
the veins of the lower limbs. Four volunteers were recruited for the study. A standardized flow was provoked with a cuff compression-decompression system placed around the lower leg. The average peak velocity in the popliteal vein of the four volunteers was 151.5 cm/s for SDUS and 105.9 cm/s for TOUS...
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt; Pihl, Michael Johannes; Udesen, Jesper;
2010-01-01
a double oscillating field. A special estimator is then used for finding both the axial and lateral velocity component, so that both magnitude and phase can be calculated. The method for generating double oscillating ultrasound fields and the special estimator are described and its performance revealed...
Liu, G.; England, S.L.; Frey, H.U.; Immel, T.J.; Lin, C.S.; Pacheco, E.E.; Häusler, K.; Doornbos, E.N.
2013-01-01
This is the first study to compare plasma depletion drifts with the ambient plasma drifts and neutral winds in the post sunset equatorial ionosphere using global-scale satellite observations. The local time and latitude variations of the drift velocities of O+ plasma depletions at 350–400 km altitud
Compact High-Velocity Atmospheric Pressure Dielectric Barrier Plasma Jet in Ambient Air
International Nuclear Information System (INIS)
In this paper, a non-thermal atmospheric pressure plasma jet at high streaming velocity operating with ambient air is highlighted. In the present technological approach, the employment of air poses a significant challenge. The high oxygen concentration in air results in a reduced concentration of reactive species in combination with a short species lifetime. The plasma jet assembly presented here contains a special dielectric barrier with a high secondary emission coefficient. In this way, the electron density and in turn the density of reactive species is increased. In addition, the plasma jet assembly is equipped with a short electrode. This leads to a higher voltage across the discharge gap and in turn to an increased density of reactive plasma species. The plasma jet is formed within and emitted by a small conical nozzle. A high-speed gas flow with gas velocity of 340 m/s was achieved at the end of the nozzle. In the jet the concentration of toxic and unwanted neutral plasma species like O3 or NOx is significantly reduced because of the shorter residence time within the plasma. The range of short-lived active plasma species is in turn considerably enhanced. The jet efficiency and action range measured through the oxidation of a test surface were determined by measuring the increase of surface tension of a polypropylene substrate via contact angle measurements after plasma treatment. Numerical modeling of the plasma plume indicates that oxygen atoms are in fact the main active species in the plasma plume. (low temperature plasma)
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...... velocity estimates are equally good. With TO there is no manual angle setting and no flow angle limitation. TO velocity estimation can also automatically handle situations where the angle varies over the cardiac cycle. More detailed temporal and spatial vector estimates with diagnostic potential...
The transverse velocity and excitation structure of the HH 110 jet
Riera, A.; López, R.; Raga, A. C.; Estalella, R.; Anglada, G.
2003-03-01
We present long-slit spectroscopic observations of the HH 110 jet obtained with the 4.2 m William Herschel Telescope. We have obtained for the first time, spectra for slit positions along and across the jet axis (at the position of knots B, C, I, J and P) to search for the observational signatures of entrainment and turbulence by studying the kinematics and the excitation structure. We find that the HH 110 flow accelerates from a velocity of 35 km s-1 in knot A up to 110 km s-1 in knot P. We find some systematic trends for the variation of the emission line ratios along the jet. No clear trends for the variation of the radial velocity are seen across the width of the jet beam. The cross sections of the jet show complex radial velocity and line emission structures which differ quite strongly from each other. Based on observations made with the 4.2 m William Herschel Telescope operated on La Palma by the Issac Newton Group of Telescopes at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.
Wei, Hua-Rong; Lacey, Roy A
2015-01-01
Experimental results of the transverse momentum spectra of final-state light flavour particles produced in gold-gold (Au-Au), copper-copper (Cu-Cu), lead-lead (Pb-Pb), proton-lead (p-Pb), and proton-proton (p-p) collisions at various energies, measured by the PHENIX, STAR, ALICE, and CMS Collaborations, are described by the Tsallis-standard (Tsallis form of Fermi-Dirac or Bose-Einstein) distribution, Tsallis distribution, and two- or three-component standard distribution, in the framework of a multisource thermal model. The effective temperatures and real temperatures (kinetic freeze-out temperatures) of interacting system at the stage of kinetic freeze-out, and the radial flow velocities of final-state particles are successively extracted from the transverse momentum spectra by the three distributions which can be in fact regarded as three types of "thermometers" and "speedometers". The dependences of effective temperatures on particle mass and centrality, and the dependences of kinetic freeze-out temperatur...
Xu, Zhen J; Song, Xiaodong
2009-08-25
Detecting temporal changes of the medium associated with major earthquakes has implications for understanding earthquake genesis. Here we report temporal changes of surface wave velocity over a large area associated with 3 major Sumatra earthquakes in 2004, 2005, and 2007. We use ambient noise correlation to retrieve empirical Green's function (EGF) of surface waves between stations. Because the process is completely repeatable, the technique is powerful in detecting possible temporal change of medium. We find that 1 excellent station pair (PSI in Indonesia and CHTO in Thailand) shows significant time shifts (up to 1.44 s) after the 2004 and 2005 events in the Rayleigh waves at 10-20 s but not in the Love waves, suggesting that the Rayleigh time shifts are not from clock error. The time shifts are frequency dependent with the largest shifts at the period band of 11-16 s. We also observe an unusual excursion approximately 1 month before the 2004 event. We obtain a total of 17 pairs for June, 2007 to June, 2008, which allow us to examine the temporal and spatial variation of the time shifts. We observed strong anomalies (up to 0.68 s) near the epicenter after the 2007 event, but not in the region further away from the source or before the event or 3 months after the event. The observations are interpreted as stress changes and subsequent relaxation in upper-mid crust in the immediate vicinity of the rupture and the broad area near the fault zone. PMID:19667205
International Nuclear Information System (INIS)
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
Energy Technology Data Exchange (ETDEWEB)
López, Rodrigo A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción (Chile); Moya, Pablo S. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Department of Physics, Catholic University of America, Washington DC, DC 20064 (United States); Muñoz, Víctor [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Valdivia, J. Alejandro [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Santiago (Chile)
2014-09-15
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.
Trofimov, Vyacheslav A.; Lysak, T. M.
2016-05-01
We demonstrate a new possibility of a soliton velocity control at its propagation in a nonlinear layered structure (1D photonic crystal) which is placed in a nonlinear ambient medium. Nonlinear response of the ambient medium, as well as the PhC layers, is cubic. At the initial time moment, a soliton is spread over a few layers of PhC. Then, soliton propagates across the layered structure because of the initial wave-vector direction presence for the laser beam. The soliton reaches the PhC faces and reflects from them or passes through the face. As a nonlinear medium surrounds the PhC, the laser beam obtains additional impulse after interaction with this medium and accelerates (or slows down or stops near the PhC face). Nonlinear response of the ambient medium can be additionally created by another laser beam which shines near the PhC faces.
Institute of Scientific and Technical Information of China (English)
Jin Xing; Li Jun; Lin Shu; Zhou Zhengrong; Kang Lanchi; Ou Yiping
2008-01-01
This paper uses the 8 broad-band stations' microseism data recorded by the Seismic Monitoring Network of Fujian Province to calculate the vertical correlation coefficient between two stationsat intervals of 5 minutes. According to the time intervals technique we obtain the different coefficients and then add the correlative coefficients. Depending on this, we extract the group velocity of Rayleigh waves from the cross correlation of the ambient seismic noise between two seismic stations and figure out the group velocity' spatial distribution. The results show that the signal noise ratio (SNR) increases proportionally to the superposition times, but the results from different days are similar to one another. Synchronously, the arrival-time is also stable and there is no obvious change when coming across typhoons. It is found the velocity of the surface wave is 2.9～3. 1km/s in Fujian Province, which is close to the observationally attained value.
Droplet velocity in horizontal two-phase air/water free jet flow in stagnant ambient
Energy Technology Data Exchange (ETDEWEB)
Surma, R.; Friedel, L. [Wissenschaftlicher Arbeitsbereich Stroemungsmechanik, TU Hamburg-Harburg, Eissendorferstr. 38, D-21073 Hamburg (Germany)
2004-08-01
For the case of an isothermal free jet flow the velocity and the size of the drops were measured with a Phase-Doppler-Anemometer. The axial velocity decay downstream from the nozzle outlet and the radial drop velocity profile are reproducible within reasonable limits, if a so-called homogeneous flow mixture density in the nozzle outlet is introduced. In case of low mass flow qualities an adjustment of the entrainment coefficient and a virtual jet origin as well as a reduced exponent for the Gaussian function type radial velocity profile is required. (Abstract Copyright [2004], Wiley Periodicals, Inc.)
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.
Farrugia, D.; Paolucci, E.; D'Amico, S.; Galea, P. M.
2014-12-01
The use of microtremors to obtain shear wave velocity (Vs) profiles of the subsurface is becoming a widespread approach due to its various advantages. Noise measurements were carried out at four sites on Malta (Central Mediterranean). Array techniques were first tested in an area where a ≈45 m layer of soft Blue Clay (BC) overlies the harder limestone. Three array configurations (two arrays of 17 geophones in an L-shape and circle respectively and one 42 geophone array in an L-shape) were tested and processed using the f-k and two SPAC techniques: Modified and Extended SPAC. No significant difference was observed in the dispersion curve from the two short arrays despite having different shapes. However, a significant variation was observed between the dispersion curve from the long and short arrays in the low frequency part. A joint inversion, using two direct search methods, of the dispersion and the H/V curve was then used to obtain the Vs profile for the site, with most of the profiles being in agreement both in terms of velocity and depth. A study was also conducted at three other sites on Malta where hard Upper Coralline Limestone (UCL) overlies the soft BC creating a velocity inversion in the soil profile. The shape of the effective dispersion curves obtained using ESAC show both an inverse dispersive trend and normal dispersion. This shape is tentatively explained in terms of the presence of higher mode Rayleigh waves. A Genetic Algorithm approach was then used to jointly invert the H/V and Rayleigh wave dispersion curve. It was observed that the BC velocity was higher when overlain by a large thickness of UCL. This could be linked to the effective pressure caused by the hard UCL, making the BC more compact, and having a higher velocity. The theoretical implications of a prominent low-velocity layer on site amplification and the interpretation of ambient noise data are investigated and discussed.
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 (Atlas, the northeastern end of the Betic Mountains and the Late Cenozoic 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.
Kohler, M. D.; Bowden, D. C.; Tsai, V. C.; Weeraratne, D. S.
2015-12-01
The Pacific-North America plate boundary in Southern California extends far west of the coastline, and a 12-month ocean bottom seismometer (OBS) array spanned the western side of the plate boundary to image lithospheric seismic velocities. Velocities are modeled through stacked cross correlations of ambient noise data. Twelve months of continuous data were used from 22 OBS stations and ~30 coastal and island Southern California Seismic Network stations. Particular attention has been paid to improving signal-to-noise ratios in the noise correlations with OBS stations by removing the effects of instrument tilt and infragravity waves. Different applications of preprocessing techniques allow us to distinguish the fundamental and first higher order Rayleigh modes, especially in deep water OBS pairs where the water layer dominates crustal sensitivity of the fundamental mode. Standard time domain and frequency domain methods are used to examine surface wave dispersion curves for group and phase velocities between 5 and 50 second periods, and these are inverted for 3D velocity structure. The results define the transition in three dimensions from continental lithospheric structure in the near-shore region to oceanic structure west of the continental borderland. While the most prominent features of the model relate to thinning of the crust west of the Patton Escarpment, other notable anomalies are present north-to-south throughout the continental borderland and along the coast from the Los Angeles Basin to the Peninsular Ranges. The velocity model will help describe the region's tectonic history, as well as provide new constraints for determination of earthquake relocations and rupture styles.
International Nuclear Information System (INIS)
The saturated alluvium located south of Yucca Mountain, Nevada is expected to serve as the final barrier to radionuclide transport from the proposed high-level nuclear waste repository at Yucca Mountain. The alluvium will act as a barrier if radionuclides breach the engineered barriers in the repository, move through the unsaturated zone beneath the repository to the water table, and then migrate through saturated volcanic tuffs to the alluvium. Three single-well injection-withdrawal tracer tests were conducted between December 2000 and April 2001 in the saturated alluviuni at NC-EWDP-19D1, a Nye County-Early Warning Drilling Program well located about 18 km south of Yucca Mountain. The tests had the objectives of (1) distinguishing between a single- and a dual-porosity conceptual radionuclide transport model for the alluvium, and (2) obtaining estimates of ambient groundwater velocity in the alluvium.
Ku, C. S.; You, S. H.; Kuo, Y. T.; Huang, B. S.; Wu, Y. M.; Chen, Y. G.; Taylor, F. W.
2015-12-01
A MW 8.1 earthquake occurred on 1 April 2007 in the western Solomon Islands. Following this event, a damaging tsunami was induced and hit the Island Gizo where the capital city of Western Province of Solomon Islands located. Several buildings of this city were destroyed and several peoples lost their lives during this earthquake. However, during this earthquake, no near source seismic instrument has been installed in this region. The seismic evaluations for the aftershock sequence, the possible earthquake early warning and tsunami warning were unavailable. For the purpose of knowing more detailed information about seismic activity in this region, we have installed 9 seismic stations (with Trillium 120PA broadband seismometer and Q330S 24bit digitizer) around the rupture zone of the 2007 earthquake since September of 2009. Within a decade, it has been demonstrated both theoretically and experimentally that the Green's function or impulse response between two seismic stations can be retrieved from the cross-correlation of ambient noise. In this study, 6 stations' observations which are more complete during 2011/10 ~ 2012/12 period, were selected for the purpose of the cross-correlation analysis of ambient seismic noise. The group velocities at period 2-20 seconds of 15 station-pairs were extracted by using multiple filter technique (MFT) method. The analyzed results of this study presented significant results of group velocities with higher frequency contents than other studies (20-60 seconds in usually cases) and opened new opportunities to study the shallow crustal structure of the western Solomon Islands.
Wei, Hua-Rong; Lacey, Roy A
2016-01-01
The transverse momentum spectra of final-state light flavor particles produced in proton-proton (p-p), copper-copper (Cu-Cu), gold-gold (Au-Au), lead-lead (Pb-Pb), and proton-lead (p-Pb) collisions for different centralities at relativistic heavy ion collider (RHIC) and large hadron collider (LHC) energies are studied in the framework of a multisource thermal model. The experimental data measured by the STAR, CMS, and ALICE Collaborations are consistent with the results calculated by the multi-component Erlang distribution and Tsallis Statistics. The effective temperature and real temperature (kinetic freeze-out temperature) of interacting system at the stage of kinetic freeze-out, the mean transverse (or radial) flow velocity and mean flow velocity of particles, and the relationships between them are extracted. The dependences of effective temperature and mean (transverse) momentum on rest mass, moving mass, centrality, and center-of-mass energy, and the dependences of kinetic freeze-out temperature and mean...
横向双极电除尘器的速度分布特征%Characteristics of the Velocity Distribution in Bipolar Transverse Plate ESP
Institute of Scientific and Technical Information of China (English)
向晓东; 聂衍韬; 丁娣
2015-01-01
为了提高现有电除尘器的除尘效果，提出一种横向双极电除尘器。用计算流体动力学（CFD ）软件的模拟结果表明，当横向双极电除尘器入口风速为1 m／s时，在距横向双极电除尘器极板迎风面40 mm范围内，平均速度小于0．7m／s，在距极板背风面40mm范围内，平均速度小于0．3m／s。不同的异极距的流速模拟对比发现，异极距在150～250 mm之间时，横向双极电除尘器极板附近的平均流速较小，远远小于普通电除尘器极板附近的风速，这将非常有利于横向双极电除尘器获得更高的除尘效率。理论、模拟与实验的结果证明，极板附近的速度分布规律呈凹形。%In order to improve the particle collection efficiency of the electrostatic precipitator (ESP) ,a bipolar transverse-plate ESP is proposed .The results obtained by the CFD software show that ,when the inlet velocity of the bipolar trans-verse plate ESP is 1 m/s ,the average velocities of windward side and leeward side are less than 0 .7 m/s and 0 .3 m/s re-spectively in the range of 40 mm from the collection electrode plate .It is also found that the average velocities are lower when the electrode distance changes between 150~250 mm .The velocity near the collection electrode plate of the bipolar transverse plate ESP is far lower than that of the ordinary ESP .Therefore ,the bipolar charged transverse-plate ESP can get higher efficiency for fine particulate collection .The theories ,simulations and experiments indicate that the velocity distribu-tion near the plates shows concave .
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.
Yao, H.; Hilst, R.D. van der; Hoop, M.V. de
2006-01-01
Empirical Green’s functions (EGFs) between pairs of seismographs can be estimated from the time derivative of the long-time cross-correlation of ambient seismic noise. These EGFs reveal velocity dispersion at relatively short periods, which can be used to resolve structures in the crust and uppermos
Energy Technology Data Exchange (ETDEWEB)
Maksimov, L.A.; Sibiriakov, B.P.; Tatarnikov, M.A.
1981-01-01
Data are given from calculations on the velocities of P- and S waves in a two-dimensional micro-inhomogenious medium whose center is filled with a gas. These calculation results demonstrate the anisotropy of this medium relative to the structure of the porous space. These calculations are in accord with measurement data in two-dimensional models.
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)
Wang, Kai; Luo, Yinhe; Yang, Yingjie
2016-05-01
We collect two months of ambient noise data recorded by 35 broad-band seismic stations in a 9 × 11 km area (1-3 km station interval) near Karamay, China, and do cross-correlation of noise data between all station pairs. Array beamforming analysis of the ambient noise data shows that ambient noise sources are unevenly distributed and the most energetic ambient noise mainly comes from azimuths of 40°-70°. As a consequence of the strong directional noise sources, surface wave components of the cross-correlations at 1-5 Hz show clearly azimuthal dependence, and direct dispersion measurements from cross-correlations are strongly biased by the dominant noise energy. This bias renders that the dispersion measurements from cross-correlations do not accurately reflect the interstation velocities of surface waves propagating directly from one station to the other, that is, the cross-correlation functions do not retrieve empirical Green's functions accurately. To correct the bias caused by unevenly distributed noise sources, we adopt an iterative inversion procedure. The iterative inversion procedure, based on plane-wave modeling, includes three steps: (1) surface wave tomography, (2) estimation of ambient noise energy and biases and (3) phase velocities correction. First, we use synthesized data to test the efficiency and stability of the iterative procedure for both homogeneous and heterogeneous media. The testing results show that: (1) the amplitudes of phase velocity bias caused by directional noise sources are significant, reaching ˜2 and ˜10 per cent for homogeneous and heterogeneous media, respectively; (2) phase velocity bias can be corrected by the iterative inversion procedure and the convergence of inversion depends on the starting phase velocity map and the complexity of the media. By applying the iterative approach to the real data in Karamay, we further show that phase velocity maps converge after 10 iterations and the phase velocity maps obtained using
Mordret, Aurélien; Rivet, Diane; Landès, Matthieu; Shapiro, Nikolaï M.
2015-01-01
We cross correlate 4 years of seismic noise from the seismic network of Piton de la Fournaise Volcano (La Réunion Island) to measure the group velocity dispersion curves of Rayleigh and Love waves. We average measurements from vertical and radial components to obtain 577 Rayleigh wave dispersion curves. The transverse components provided 395 Love wave dispersion curves. We regionalize the group velocities measurements into 2-D velocity maps between 0.4 and 8 s. Finally, we locally inverted these maps for a pseudo 3-D anisotropic shear-velocity model down to 3 km below the sea level using a Neighborhood Algorithm. The 3-D isotropic shear-wave model shows three distinct high-velocity anomalies surrounded by a low-velocity ring. The anomaly located below the present "Plaine des Sables" could be related to an old intrusive body at the location of the former volcanic center before it migrated toward its present location. The second high-velocity body located below the summit of the volcano likely corresponds to the actual preferential dyke intrusion zone as highlighted by the seismicity. The third high-velocity anomaly located below the "Grandes Pentes" and the "Grand Brûlé" areas and is an imprint of the solidified magma chamber of the dismantled "Les Alizés" Volcano. Radial anisotropy shows two main anomalies: positive anisotropy above sea level highlighting the recent edifice of Piton de la Fournaise with an accumulation of horizontal lava flows and the second one below the sea level with a negative anisotropy corresponding to the ancient edifice of Piton de la Fournaise dominated by intrusions of vertical dykes.
Vassallo, Maurizio; Festa, Gaetano; Bobbio, Antonella; Serra, Marcello
2016-06-01
We extracted the Green's functions from cross correlation of ambient noise recorded at broadband stations located across the Apennine belt, Southern Italy. Continuous records at 26 seismic stations acquired for 3 years were analyzed. We found the emergence of surface waves in the whole range of the investigated distances (10-140 km) with energy confined in the frequency band 0.04-0.09 Hz. This phase reproduces Rayleigh waves generated by earthquakes in the same frequency range. Arrival time of Rayleigh waves was picked at all the couples of stations to obtain the average group velocity along the path connecting the two stations. The picks were inverted in separated frequency bands to get group velocity maps then used to obtain an S wave velocity model. Penetration depth of the model ranges between 12 and 25 km, depending on the velocity values and on the depth of the interfaces, here associated to strong velocity gradients. We found a low-velocity anomaly in the region bounded by the two main faults that generated the 1980, M 6.9 Irpinia earthquake. A second anomaly was retrieved in the southeast part of the region and can be ascribed to a reminiscence of the Adria slab under the Apennine Chain.
Navarro, M.; Vidal, F.; García-Jerez, A.; Alguacil, G.; Ruíz-Sibaja, A.; Aguirre, J.; Cárdenas, R.
2013-05-01
The shallow geological structure of Tapachula town has been estimated applying an association of the spatial autocorrelation (SPAC) method and the horizontal-to-vertical spectral ratio (HVSR, Nakamura 1989) method for ambient noise. Regular pentagonal arrays with radii up to 24 m have been employed for velocity computation. The measurements were carried out at six open spaces. Vertical components of ground motion, excited by ambient noise, were recorded at the surface. Five high-sensitivity sensors surrounding a sixth central sensor with same characteristics were used. All the records were analysed by using an implementation of the SPAC method (Aki, 1957). The phase-velocity of the Rg-wave was computed for each frequency from the correlation coefficient. The frequencies of the obtained curves ranged from 2.7 to 16.5 Hz and the phase velocity values varied between 226 and 594 m s-1. Nakamura's method was applied to determine the ground predominant period in the center of such arrays. The predominant period values vary in the 0.2-0.8 s range. Inversions of the S-wave velocity profiles corresponding to the six array sites have been achieved by using dispersion curves derived from SPAC and HVSR shapes. In order to classify the top shallow structure of Tapachula town, following the characterization of site adopted in several seismic codes (e.g. NEHRP 1994, Eurocode-8), the average shear-wave velocity of the upper 30 m (VS30) has been calculated. The results show differences between central part of the town and the peripheral zones close to both rivers rounding the city.
LongJohn, T.; Kelly, C.; Seats, K.; Lawrence, J.
2013-12-01
Hydrothermal system studies are important for geothermal energy exploration and geysers are also believed to be functional analogues of volcanoes. However, the mechanism of eruption and the characteristics of the plumbing system of most geysers are poorly understood given their subsurface location and sparse global distribution. An accurate acoustic velocity model could yield important insight into subsurface density and thermal variations in a geyser system. Passive seismic data was collected at El Jefe geyser in El Tatio Geyser Field, northern Chile during October of 2012. An array of 6 broadband seismometers and 51 high frequency geophones were deployed for ~1 week in a grid array with station spacing of 2-10 meters (geophones) and 3-50 meters (broadbands) centered around El Jefe Geyser. Using ambient seismic noise generated by the geyser system, I constructed a preliminary subsurface velocity model for El Jefe Geyser. As a result of the close station spacing, the seismic signals sampled shallow depths corresponding to high frequency waves. Coherent seismic records from different seismic station pairs were cross correlated to produce noise correlation functions (NCF). Adaptive covariance filtering and stacking techniques were utilized to amplify the signal of the NCFs and one-dimensional velocities between station pairs at varying depths were determined. Next, a tomographic inversion was done to interpolate between the one-dimensional velocities and produce a three-dimensional velocity model for the entire geyser area. From the velocity model, we can identify regions of low and high acoustic velocity that potentially represent water reservoirs and bedrock respectively.
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
Ugalde, Arantza; Gaite, Beatriz; Villaseñor, Antonio
2016-04-01
During September 2013, the injection of the base gas in a depleted oil reservoir used as an underground natural gas storage (CASTOR) caused a sudden seismic activity increase in the eastern coast of Spain. As a result, a compact cluster of more than 550 earthquakes with magnitudes mbLg > 0.7 were located in the shallow offshore area of the Gulf of Valencia during two months. The strongest event, having a magnitude of Mw=4.2, was followed by two Mw=4.1 events the day after and took place once the gas injection activities had finished. Using the seismic data recorded by permanent stations at more than 25 km from the injection well, we applied coda wave interferometry to monitor changes in seismic velocity structure between similar earthquakes. Then we solved for a continuous function of velocity changes with time by combining observations from all the closely located earthquake sources. The rate of repeating events allowed measurements of relative velocity variations for about 30 days on a daily scale. To extend the analysis in time, we also processed the continuous data using the autocorrelation of band-pass filtered ambient seismic noise. A 10-day average was required to achieve a sufficient signal-to-noise ratio in the 0.2-0.5 Hz and 0.5-1 Hz frequency bands. We quantified the time lags between two traces in the frequency and time domains by means of the Moving Window Cross Spectral Analysis and a Dynamic Time Warping technique, respectively. Injection of fluids in geologic formations causes variations in seismic velocities associated to changes in fluid saturation, increase in pore pressure or opening or enlargement of cracks due to the injection process. Time delays associated with stress changes caused by moderate to large earthquakes have also been established. In this work, we found no velocity changes during the gas injection period nor on the occasion of the Mw 4.2 earthquake. The sensitivity of the method is dependent on the seismic network geometry and
Witek, M.; Kang, T. S.; van der Lee, S.
2015-12-01
We have collected three-component data from 122 Korean accelerometer stations for the month of December in 2014. We apply similar techniques described by Zha et al. (2013) to retrieve accurate station orientation angles, in order to rotate the horizontal component data into the radial and transverse frame of reference, and for subsequent measurement of Love wave group velocity dispersion. We simultaneously normalize all three components of a daily noise record via the frequency-time normalization (FTN) method. Each component is divided by the average signal envelope in an effort to retain relative amplitude information between all three components. Station orientations are found by a grid search for the orientation azimuth which maximizes the coherency between the radial-vertical cross-correlation and the Hilbert transformed vertical-vertical cross-correlation. After measuring orientation angles, we cross-correlate and rotate the data. Typically, the group velocity dispersion curves are measured using the frequency time analysis technique (FTAN), effectively producing spectrograms with significant uncertainty in the time-frequency plane. The spectrogram approach retains only the amplitude information of the short-time Fourier transform (STFT). However, Kodera et al (1976) show that by taking into account the phase information, the concepts of instantaneous frequency and group-time delay can be used to compute the first moment of the signal power in the frequency and time domains. During energy reassignment, the signal power calculated using the STFT at a point (t0,f0t_0, f_0) is reassigned to the location of the first moment (t^g,f^ihat{t}_g,hat{f}_i), where t^ghat{t}_g is the group-time delay and f^ihat{f}_i is the instantaneous frequency. We apply the method of energy reassignment to produce precise Rayleigh and Love wave group velocity measurements in the frequency range 0.1 - 1.0 Hz. Tests on synthetic data show more accurate retrieval of group velocities at
Pilz, M.; Parolai, S.; Picozzi, M.; Wang, R.; Leyton, F.; Campos, J. A.; Zschau, J.
2009-12-01
Generally, the most intense shaking during an earthquake occurs near the rupture fault and decreases with distance away from the fault. However, in a single earthquake the shaking at one site can easily be several times stronger than at another site, even when their distance from the rupture fault is the same. Such site effects are mainly caused by the softness of the soil near the surface and by the thickness of the sediments above hard rock. Seismic site characterization therefore requires usually substantial investment both in time and money for geophysical data acquisition. On the other hand, the necessity of estimating seismic risk for large urban areas like Santiago de Chile wants for at least a first order classification of soil and building vulnerability and therefore needs the definition of proxies. Recently, Wald and Allen (2007) suggested that the slope of topography might serve as a suitable parameter for the estimation of site effects irrespective of the spatial resolution used. Measurements of seismic noise at 146 sites have been carried out in the northern part of Santiago de Chile to determine the fundamental resonance frequency of the sites. The spatial variation in the thickness of the sedimentary cover, known from previous gravimetric investigations, varies significantly over short scale and is roughly retrieved from the peak in the horizontal-to-vertical (H/V) ratios of ambient noise. We inverted the H/V spectra individually for receiving local S-wave velocity profiles. For the inversion procedure, we also used additional geological and geophysical information. The resulting 3D model was derived for a 26 km X 12 km area by interpolation between the single S-wave velocity profiles with a kriging technique and shows good agreement with the few existing velocity profiles but also allows to image the entire area as well as deeper parts of the basin in more detail. Significant variations in the S-wave velocity-depth gradient are found. The wealth of
Lepore, Simone; Gomez, Martin; Draganov, Deyan
2015-04-01
The main force driving the tectonics in South America is the subduction of the Nazca Plate below the South American plate. The subduction process generated numerous volcanoes in both Chile and Argentina, of which the majority is concentrated along the Chilean Argentine border. The recent explosive eruptions of some volcanoescaused concern of the population in both countries. At the beginning of 2012, a large temporary array was installed in the Malargüe region, Mendoza, Argentina, with the purpose of imaging the subsurface and monitoring the tectonic activity. The array was deployed until the end of 2012 to record continuously ambient noise and the local, regional, and global seismicity. It consisted of 38 seismic stations divided in two sub arrays, namely the PV array of six stations located on the east flank of the Peteroa volcano, and the T array of thirty two stations spread out on a plateau just north east of the town of Malargüe. Here,the focus will be on the PV array, which has a patch-like shape. Due to the intra-station distances, we chose to use for surface-wave retrieval the bands 0.8 Hz ÷ 4.0 Hz, 10 Hz ÷ 25 Hz. At the investigated area, most of the year there is little anthropogenic noise, which normally dominates frequencies above 1 Hz, meaning that the selected frequency bands can be used for surface-wave retrieval from noise. Using beamforming, we showed that for these bands, the noise is illuminating the stations from the west. This means that a correct surface-wave arrivals can be retrieved for station pairs oriented in that direction. Because of this, we used for retrieval only such station pairs. We cross-correlated the recordings on the vertical components and retrieved Rayleigh waves. By manual picking, we estimated for both bands velocity dispersion curves from the retrieved surface-wave arrivals. The curves were then inverted to obtain the velocity structure under the stations. The obtained S wave velocity depth profiles for the 10 Hz
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...
Directory of Open Access Journals (Sweden)
Marcio Ricardo Salla
2008-12-01
Full Text Available The size of the cross section of an ozonization column influences its hydrodynamic characteristics, which, on its turn, has effects on phenomena that depend on the relative movement between gas bubbles and liquid. To observe the influence of the cross sectional area on gas concentration and bubbles velocity, two columns were used. The first column had a square cross section with side of 0.19m and the second had a circular cross section with diameter of 0.10 m. The ascendant velocities of the bubbles and their concentration were measured in both columns and compared. The transversal spread of the plumes of bubbles was also quantified. The results show that the increase of the cross section of the column, in the proportion studied here, does not result in a similar increase of the cross section of the ascending plume of bubbles. Furthermore, the results of average velocities and concentrations obtained for the smallest cross section resulted independent of the liquid level in the column, while the results for the largest cross section showed to be dependent of this level. The ratio between the cross sectional areas of the larger and the smaller plumes of bubbles decreases for higher distances to the bottom of the columns.La sección transversal de una columna de ozonización posee influencia directa sobre las características hidrodinámicas de esa columna, lo que se refleja en los fenómenos que dependen de la transferencia de masa en la interfase gas-líquido. En este estudio se utilizaron dos columnas con secciones transversales diferentes cuanto a la forma y al tamaño. La primera con sección transversal cuadrada de 0,19m y la segunda con sección transversal circular de 0,10 m de diámetro. Se midieron las velocidades ascensionales de las burbujas y su concentración. Los resultados obtenidos muestran que el aumento de la sección transversal en la proporción aquí estudiada no conlleva un aumento semejante de la sección transversal de la
Institute of Scientific and Technical Information of China (English)
张兴敢; 柏业超
2009-01-01
The one-order phase of the echo changes if there is relative radial moving between the object and the radar, i.e., the Doppler effect. The Doppler effect is widely used in radar signal processing. The transverse motion of the object cannot change the one-order phase of the echo, but the high-order phase. The high-order Doppler effect of the transverse moving target is presented and a new algorithm for obtaining the transverse velocity is given. The scalar velocity of a target moving steadily in any direction can be calculated with one-order and two-order items of the echo phase. The calculating method and simulating results are given.As the transverse speed is 900 km/h, the speed calculation error is less than 0.06% if SNR of echo signal is higher than 0 dB.%目标与雷达存在相对径向运动时回波相位一次项发生变化,产生多普勒效应.多普勒效应广泛用于雷达信号处理.目标横向运动分量不会导致回波相位一次项变化,但会导致回波相位高次项的变化,据此本文提出横向运动物体的高阶多普勒效应及其横向速度的计算方法.高阶多普勒效应与常规多普勒效应配合可以计算任意向平稳运动物体的标量速度.文中给出了计算方法和仿真结果.当目标横向运动速度为900 km/h,且回波信号信噪比大于0 dB时,计算误差小于0.06 %.
... to overcome, circumvent, or compensate for permanent disabilities. Rehabilitation as yet cannot reverse the physical damage resulting from transverse myelitis or other forms of spinal cord injury. But it can help people, even those with ...
... functioning while hoping for either complete or partial spontaneous recovery of the nervous system. If an individual ... Throughout the U.S. and Worldwide NINDS Clinical Trials Organizations Column1 Column2 Transverse Myelitis Association 1787 Sutter Parkway ...
Budi-Santoso, Agus; Lesage, Philippe
2016-04-01
We present a study of the seismic velocity variations that occurred in the structure before the large 2010 eruption of Merapi volcano. For the first time to our knowledge, the technique of Coda Wave Interferometry is applied to both families of similar events (multiplets) and to correlation functions of seismic noise. About half of the seismic events recorded at the summit stations belong to one of the ten multiplets identified, including 120 similar events that occurred in the last 20 hours preceding the eruption onset. Daily noise cross-correlation functions (NCF) were calculated for the six pairs of short-period stations available. Using the stretching method, we estimate time series of apparent velocity variation (AVV) for each multiplet and each pair of stations. No significant velocity change is detected until September 2010. From 10 October to the beginning of the eruption on 26 October, a complex pattern of AVV is observed with amplitude of up to ±1.5%. Velocity decrease is first observed from families of deep events and then from shallow earthquakes. In the same period, AVV with different signs and chronologies are estimated from NCF calculated for various station pairs. The location in the horizontal plane of the velocity perturbations related with the AVV obtained from NCF is estimated by using an approach based on the radiative transfer approximation. Although their spatial resolution is limited, the resulting maps display velocity decrease in the upper part of the edifice in the period 12-25 October. After the eruption onset, the pattern of velocity perturbations is significantly modified with respect to the previous one. We interpret these velocity variations in the framework of a scenario of magmatic intrusion that integrates most observations. The perturbation of the stress field associated with the magma migration can induce both decrease and increase of the seismic velocity of rocks. Thus the detected apparent velocity variations can be
Budi-Santoso, Agus; Lesage, Philippe
2016-07-01
We present a study of the seismic velocity variations that occurred in the structure before the large 2010 eruption of Merapi volcano. For the first time to our knowledge, the technique of coda wave interferometry is applied to both families of similar events (multiplets) and to correlation functions of seismic noise. About half of the seismic events recorded at the summit stations belong to one of the ten multiplets identified, including 120 similar events that occurred in the last 20 hr preceding the eruption onset. Daily noise cross-correlation functions (NCF) were calculated for the six pairs of short-period stations available. Using the stretching method, we estimate time-series of apparent velocity variation (AVV) for each multiplet and each pair of stations. No significant velocity change is detected until September 2010. From 10 October to the beginning of the eruption on 26 October, a complex pattern of AVV is observed with amplitude of up to ±1.5 per cent. Velocity decrease is first observed from families of deep events and then from shallow earthquakes. In the same period, AVV with different signs and chronologies are estimated from NCF calculated for various station pairs. The location in the horizontal plane of the velocity perturbations related with the AVV obtained from NCF is estimated by using an approach based on the radiative transfer approximation. Although their spatial resolution is limited, the resulting maps display velocity decrease in the upper part of the edifice in the period 12-25 October. After the eruption onset, the pattern of velocity perturbations is significantly modified with respect to the previous one. We interpret these velocity variations in the framework of a scenario of magmatic intrusion that integrates most observations. The perturbation of the stress field associated with the magma migration can induce both decrease and increase of the seismic velocity of rocks. Thus the detected AVVs can be considered as precursors of
International Nuclear Information System (INIS)
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
Energy Technology Data Exchange (ETDEWEB)
Black, M.J.; Motaghedi, B.; Robitaille, Y.
1980-05-01
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.
Balme, M. R.; Pathare, A.; Metzger, S. M.; Towner, M.C.; Lewis, S R; Spiga, A.; Fenton, L.; Renno, N. O.; Elliott, H. M.; Saca, F. A.; Michaels, T.; Russell, P; Verdasca, J.
2012-01-01
Dust devils – convective vortices made visible by the dust and debris they entrain – are common in arid environments and have been observed on Earth and Mars. Martian dust devils have been identified both in images taken at the surface and in remote sensing observations from orbiting spacecraft. Observations from landing craft and orbiting instruments have allowed the dust devil translational forward motion (ground velocity) to be calculated, but it is unclear how these velocities relate to t...
DEFF Research Database (Denmark)
2000-01-01
Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...... estimator automatically compensates for the axial velocity, when determining the transverse velocity by using fourth order moments rather than second order moments. The estimation is optimized by using a lag different from one in the estimation process, and noise artifacts are reduced by using averaging of...... RF samples. Further, compensation for the axial velocity can be introduced, and the velocity estimation is done at a fixed depth in tissue to reduce spatial velocity dispersion....
Experimental investigation of transverse flow estimation using transverse oscillation
DEFF Research Database (Denmark)
Udesen, Jesper; Jensen, Jørgen Arendt
2003-01-01
. The flow is generated with the Compuflow 1000 programmable flow pump giving a parabolic velocity profile of the blood mimicking fluid in the flow phantom. The profiles are estimated for 310 trials each containing of 32 data vectors. The relative mean bias over entire blood vessel is found to be 10......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 of...... the approach, this paper presents simulated and experimental results, obtained at a blood velocity angle transverse to the ultrasound beam. The Field II program is used to simulate a setup with a 128 element linear array transducer. At a depth 27 mm a virtual blood vessel of radius 2.4 mm is situated...
Li, Xianguo
Linear temporal instability analysis of a moving thin viscous liquid sheet of uniform thickness in an inviscid gas medium shows that surface tension always opposes, while surrounding gas and relative velocity between the sheet and gas favour the onset and development of instability. For gas Weber number smaller than the density ratio of gas to liquid, liquid viscosity enhances instability; If gas Weber number is slightly larger, aerodynamic and viscosity -induced instabilities interact with each other, displaying complicated effects of viscosity via Ohnesorge number; For much larger values of gas Weber numbers, aerodynamic instability dominates, liquid viscosity reduces disturbance growth rate and increases the dominant wavelength. Droplet probability distribution function (PDF) in sprays is formulated through information theory without resorting to the details of atomization processes. The derived analytical droplet size PDF is Nukiyama-Tanasawa type if conservation of mass is considered alone. If conservation of mass, momentum and energy is all taken into account, the joint droplet size and velocity PDF depends on Weber number, and compares favourably with measurements. Droplet velocity PDF is truncated Gaussian for any specific droplet size. Mean velocity approaches a constant value and velocity variance decreases as droplet size increases. Mean droplet diameters calculated agree well with observations. The computation indicates that atomization efficiency is very low, usually less than 1%. Droplet size, velocity and temperature PDF in sprays under combusting environment has also been derived. Effects of combustion on PDF occur mainly through the heat transferred into liquid sheet prior to its breakup. Experimental studies identify three modes of spray behaviours due to its interaction with various annular air flows, and show that bluff-body type of combustor has ability and easement to control aerodynamically spray angle, shape and droplet trajectories. It is
Ruzek, Bohuslav
2010-05-01
Joint inversion of P-waveforms from distant earthquakes recorded by 41 broadband seismic stations located on the territory of Bohemian Massif and Rayleigh/Love group velocities gained by using cross-correlation technique applied to seismic noise recorded by the same set of broadband stations has been performed. Together with joint inversion also individual inversions using single data sets have been carried out. All computations were arranged inside isotropic, locally 1D layered models. Remarkable result is indication of horizons just above MOHO in the lower crust below some stations where low-velocity S-wave channel is needed in order to ensure correct modeling of measured events. This indication follows both from individual and joint inversions. P-waveform inversion is based on using a set of 271 well-recorded teleseismic events from epicentral distances 3000-10000 km. The inversion was originally based on the popular 'receiver function' methodology, but due to the instability of needed deconvolution it was modified. We search for optimum layered velocity model, which correctly projects radial to vertical components (and vice versa, deconvolution is no more needed). Regarding second source of data, both Rayleigh and Love surface waves were extracted from seismic noise by using cross-correlation. Long time series covering the period 2001-2009 were processed. Such measurements provide group velocities between arbitrary pairs of stations. Local group velocity dispersion curves were computed by using 2D tomography-like approach for periods 4-20 s. The subject of inversion (both individual and joint) were just group velocity dispersion curves. Inversion required exhaustive computations. We used HPC cluster nemo.ig.cas.cz and ANNI inversion software, capable to run in parallel regime.
Transverse correlation: An efficient transverse flow estimator - initial results
DEFF Research Database (Denmark)
Holfort, Iben Kraglund; Henze, Lasse; Kortbek, Jacob; Jensen, Jørgen Arendt
vascular hemodynamics, the flow angle cannot easily be found as the angle is temporally and spatially variant. Additionally the precision of traditional methods is severely lowered for high flow angles, and they breakdown for a purely transverse flow. To overcome these problems we propose a new method 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, a...... at 45 degrees. The method performs stable down to a signal-to-noise ratio of 0 dB, where a standard deviation of 5.5% and a bias of 1.2% is achieved....
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
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.
Spica, Zack; Perton, Mathieu; Calò, Marco; Legrand, Denis; Córdoba Montiel, Francisco; Iglesias, Arturo
2016-07-01
This work presents an innovative strategy to enhance the resolution of surface wave tomography obtained from ambient noise cross-correlation (C1) by bridging asynchronous seismic networks through the correlation of coda of correlations (C3). Rayleigh wave group dispersion curves show consistent results between synchronous and asynchronous stations. Rayleigh wave group travel times are inverted to construct velocity-period maps with unprecedented resolution for a region covering Mexico and the southern United States. The resulting period maps are then used to regionalize dispersion curves in order to obtain local 1-D shear velocity models (VS) of the crust and uppermost mantle in every cell of a grid of 0.4°. The 1-D structures are obtained by iteratively adding layers until reaching a given misfit, and a global tomography model is considered as an input for depths below 150 km. Finally, a high-resolution 3-D VS model is obtained from these inversions. The major structures observed in the 3-D model are in agreement with the tectonic-geodynamic features and with previous regional and local studies. It also offers new insights to understand the present and past tectonic evolution of the region.
Spica, Zack; Perton, Mathieu; Calò, Marco; Legrand, Denis; Córdoba-Montiel, Francisco; Iglesias, Arturo
2016-09-01
This work presents an innovative strategy to enhance the resolution of surface wave tomography obtained from ambient noise cross-correlation (C1) by bridging asynchronous seismic networks through the correlation of coda of correlations (C3). Rayleigh wave group dispersion curves show consistent results between synchronous and asynchronous stations. Rayleigh wave group traveltimes are inverted to construct velocity-period maps with unprecedented resolution for a region covering Mexico and the southern United States. The resulting period maps are then used to regionalize dispersion curves in order to obtain local 1-D shear velocity models (VS) of the crust and uppermost mantle in every cell of a grid of 0.4°. The 1-D structures are obtained by iteratively adding layers until reaching a given misfit, and a global tomography model is considered as an input for depths below 150 km. Finally, a high-resolution 3-D VS model is obtained from these inversions. The major structures observed in the 3-D model are in agreement with the tectonic-geodynamic features and with previous regional and local studies. It also offers new insights to understand the present and past tectonic evolution of the region.
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.)
Introduction to vector velocity imaging
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt; Udesen, Jesper; Hansen, Kristoffer Lindskov;
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...
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....... Using a correlation search can also yield the direction, and the full velocity vector is thereby found. An examples from a flow rig is shown....
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...... aspect of the aesthetization of modern culture in general, from architecture, transport and urbanized lifeforms to film, sound art, installation art and digital environments. This presentation will discuss the key aspects of ambient aesthetization, including issues such as objectlessness...
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...
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 the GNU LGPL licence version 3 or higher.
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 th
Transverse Injection Experiment
International Nuclear Information System (INIS)
The motion of a plasma stream injected transverse to a magnetic field has been discussed by several authors. In early experiments with the injection of a fast (50 to 70 cm/μsec) dense (1014 ion/cm3) plasma transverse to a magnetic field, a self polarization electric field was observed and the stream crossed the magnetic field with an E x B drift. The magnetic field was only slightly disturbed by the stream (| ΔB/B | <0.1) while the drift across magnetic fields up to 5 kG was at approximately the velocity of the injected stream. The height of the stream in the direction of V x B is compressed as it drifts into high magnetic field regions. At the same time, electron density measurements using interferometry techniques with the He-Ne laser show that the transverse field up to 7 kG causes no appreciable spreading of the stream to take place in the direction of B. Of interest is the action of the stream as it crosses a region where magnetic field lines reverse direction about a field null line. As the stream proceeds across the separatrix between the two field line directions, the electric field must change direction if the stream drift is to continue. The stream halts in the region of the separatrix while large currents are measured along magnetic field lines connecting the front of the stream with the following portions. Insulators placed to interrupt the current allow the stream to proceed into the reversed field region. By making use of the inductance associated with the depolarization current when magnetic field lines are tied at some distance to the side of the stream, a separation of fast and slow stream components can be made. The cutoff of the slow stream component is observed with the He-Ne laser interferometry techniques. Electric field measurements at several points along the stream show some of the more complicated features of the plasma flow. (author)
International Nuclear Information System (INIS)
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 (40K, 54Mn, 95Zr + 95Nb, 103Ru + 106Rh, 137Cs, 137Ba, 140Ba + 140La, 144Ce + 144Pr) 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
Transverse Myelitis Association
... first large-scale North-American study of pediatric transverse myelitis LEARN MORE We are seeking over 100 patients ... TMA QUALITY OF LIFE FAMILY CAMP 2016 THE TRANSVERSE MYELITIS ASSOCIATION ADVOCATING FOR THOSE WITH ACUTE DISSEMINATED ENCEPHALOMYELITIS, ...
Transversity: theory and phenomenology
D'Alesio, Umberto
2013-01-01
The distribution of transversely polarized quarks inside a transversely polarized nucleon, known as transversity, encodes a basic piece of information on the nucleon structure, sharing the same status with the more familiar unpolarized and helicity distributions. I will review its properties and discuss different ways to access it, with highlights and limitations. Recent phenomenological extractions and perspectives are also presented.
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...
Karam, Maria; Hare, Jonathon; Lewis, Paul; schraefel, m.c.
2006-01-01
We present Ambient Gestures, a novel gesture-based system designed to support ubiquitous ‘in the environment’ interactions with everyday computing technology. Hand gestures and audio feedback allow users to control computer applications without reliance on a graphical user interface, and without having to switch from the context of a non-computer task to the context of the computer. The Ambient Gestures system is composed of a vision recognition software application, a set of gestures to be p...
Transversity and Meson Photoproduction
Goldstein, G R; Goldstein, Gary R.; Gamberg, Leonard
2002-01-01
Both meson photoproduction and semi-inclusive deep inelastic scattering can potentially probe transversity in the nucleon. We explore how that potential can be realized dynamically. The role of rescattering in both exclusive and inclusive meson production as a source for transverse polarization asymmetry is examined. We use a dynamical model to calculate the asymmetry and relate that to the transversity distribution of the nucleon.
Jaffe, R. L.
1997-01-01
I review the ways that have been proposed to measure the quark transversity distribution in the nucleon. I then explain a proposal, developed by Xuemin Jin, Jian Tang and myself, to measure transversity through the final state interaction between two mesons ($\\pi\\pi$, $K \\bar K$, or $\\pi K$) produced in the current fragmentation region in deep inelastic scattering on a transversely polarized nucleon.
Sanders, David; Gegov, Alexander
2006-01-01
This paper considers some history and the state of the art of Ambient Intelligence and from that seeks to identify new topics and future work. Ubiquitous computing, communications, human-centric computer interaction, embedded systems, context awareness, adaptive systems and distributed device networks are considered.
Weber, W; Aarts, E
2005-01-01
Addresses ambient intelligence used to support human contacts and accompany an individual''s path through the complicated modern world, from applications that are imminent, since they use essentially existing technologies, to ambitious ideas whose realization is still far away, due to major unsolved technical challenges.
Makin, Alexis David James
2011-01-01
This Thesis, entitled ‘Velocity Memory’ is submitted to the University of Manchester by Alexis David James Makin (30/09/2010) for the degree of Doctor of Philosophy. It is known that primates are sensitive to the velocity of moving objects. We can also remember velocity information after moving objects disappear. This cognitive faculty has been investigated before, however, the literature on velocity memory to date has been fragmented. For example, velocity memory has been disparately descri...
Transverse gravity versus observations
International Nuclear Information System (INIS)
Theories of gravity invariant under those diffeomorphisms generated by transverse vectors, ∂μξμ = 0 are considered. Such theories are dubbed transverse, and differ from General Relativity in that the determinant of the metric, g, is a transverse scalar. We comment on diverse ways in which these models can be constrained using a variety of observations. Generically, an additional scalar degree of freedom mediates the interaction, so the usual constraints on scalar-tensor theories have to be imposed. If the purely gravitational part is Einstein-Hilbert but the matter action is transverse, the models predict that the three a priori different concepts of mass (gravitational active and gravitational passive as well as inertial) are not equivalent anymore. These transverse deviations from General Relativity are therefore tightly constrained, actually correlated with existing bounds on violations of the equivalence principle, local violations of Newton's third law and/or violation of Local Position Invariance
Chatter in a transverse grinding process
Yan, Yao; Xu, Jian; Wiercigroch, Marian
2014-02-01
In transverse grinding, the wheel moves along the workpiece, which induces unique grinding dynamics. To understand these dynamic phenomena, specifically the grinding chatter, a new dynamical model of the process is proposed, in which the wheel position is assumed to be quasi-static since the transverse wheel velocity is small. From the stability and bifurcation analyses of the chatter vibration, it appears that the dynamics of the process is governed by the quasi-static interactions. Moreover, the obtained results also show that the wheel and workpiece chatters are quite different, having continuous and intermittent characters respectively.
Algorithms for estimating blood velocities using ultrasound
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt
2000-01-01
Ultrasound has been used intensively for the last 15 years for studying the hemodynamics of the human body. Systems for determining both the velocity distribution at one point of interest (spectral systems) and for displaying a map of velocity in real time have been constructed. A number of schemes...... 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...
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....
Nikola Vlacic
2010-01-01
In this project, we investigated if it is feasible for a single staged rocket with constant thrust to attain escape velocity. We derived an equation for the velocity and position of a single staged rocket that launches vertically. From this equation, we determined if an ideal model of a rocket is able to reach escape velocity.
Transversity measurements at HERMES
Diefenthaler, Markus
2005-01-01
Azimuthal single-spin asymmetries (SSA) in semi-inclusive electroproduction of charged pions in deep-inelastic scattering (DIS) of positrons on a transversely polarised hydrogen target are presented. Azimuthal moments for both the Collins and the Sivers mechanism are extracted. In addition the subleading-twist contribution due to the transverse spin component from SSA on a longitudinally polarised hydrogen target is evaluated.
Basten, Twan; de Groot, Harmke
2007-01-01
""This book is truly an eye-opener as it is the first book that relates the dream scenarios of Ambient Intelligence quantitatively to the technical challenges and requirements of the huge distributed and interoperable embedded systems needed to implement AmI systems in the real world. This book is strongly recommended to a wide spectrum of engineers interested to embark in this rapidly emerging and fascinating technology."" (From the foreword by Hugo De Man, Professor K.U. Leuven and Senior Research Fellow IMEC)
Analytic solution for relativistic transverse flow at the softest point
Biro, T S
2000-01-01
We obtain an extension of Bjorken's 1+1 dimensional scaling relativistic flow solution to relativistic transverse velocities with cylindrical symmetry in 1+3 dimensions at constant, homogeneous pressure (vanishing sound velocity). This can be the situation during a first order phase transition converting quark matter into hadron matter in relativistic heavy ion collisions.
Recent advances in blood flow vector velocity imaging
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt; Nikolov, Svetoslav; Udesen, Jesper;
2011-01-01
A number of methods for ultrasound vector velocity imaging are presented in the paper. The transverse oscillation (TO) method can estimate the velocity transverse to the ultrasound beam by introducing a lateral oscillation in the received ultrasound field. The approach has been thoroughly investi...
Transverse excitations in liquid metals
Hosokawa, S.; Munejiri, S.; Inui, M.; Kajihara, Y.; Pilgrim, W.-C.; Baron, A. Q. R.; Shimojo, F.; Hoshino, K.
2013-02-01
The transverse acoustic excitation modes were detected by inelastic x-ray scattering in liquid Ga, Cu and Fe in the Q range around 10 nm-1 using a third-generation synchrotron radiation facility, SPring-8, although these liquid metals are mostly described by a simple hard-sphere liquid. Ab initio molecular dynamics simulations clearly support this finding for liquid Ga. From the detailed analyses for the S(Q,ω) spectra with good statistic qualities, the lifetime of less than 1 ps and the propagating length of less than 1 nm can be estimated for the transverse acoustic phonon modes, which correspond to the lifetime and size of cages formed instantaneously in these liquid metals. The microscopic Poisson's ratio estimated from the dynamic velocities of sound is 0.42 for liquid Ga and about -0.2 for liquid transition metals, indicating a rubber-like soft and extremely hard elastic properties of the cage clusters, respectively. The origin of these microscopic elastic properties is discussed in detail.
Transverse spin and transverse momentum in scattering of plane waves
Saha, Sudipta; Ray, Subir K; Banerjee, Ayan; Gupta, Subhasish Dutta; Ghosh, Nirmalya
2016-01-01
We study the near field to the far field evolution of spin angular momentum (SAM) density and the Poynting vector of the scattered waves from spherical scatterers. The results show that at the near field, the SAM density and the Poynting vector are dominated by their transverse components. While the former (transverse SAM) is independent of the helicity of the incident circular polarization state, the latter (transverse Poynting vector) depends upon the polarization state. It is further demonstrated that the magnitudes and the spatial extent of the transverse SAM and the transverse momentum components can be controllably enhanced by exploiting the interference of the transverse electric and transverse magnetic scattering modes.
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...
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...... 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...
Nondiffracting transversally polarized beam.
Yuan, G H; Wei, S B; Yuan, X-C
2011-09-01
Generation of a nondiffracting transversally polarized beam by means of transmitting an azimuthally polarized beam through a multibelt spiral phase hologram and then highly focusing by a high-NA lens is presented. A relatively long depth of focus (∼4.84λ) of the electric field with only radial and azimuthal components is achieved. The polarization of the wavefront near the focal plane is analyzed in detail by calculating the Stokes polarization parameters. It is found that the polarization is spatially varying and entirely transversally polarized, and the polarization singularity disappears at the beam center, which makes the central bright channel possible. PMID:21886250
Turbine airfoil with ambient cooling system
Energy Technology Data Exchange (ETDEWEB)
Campbell, Jr, Christian X.; Marra, John J.; Marsh, Jan H.
2016-06-07
A turbine airfoil usable in a turbine engine and having at least one ambient air cooling system is disclosed. At least a portion of the cooling system may include one or more cooling channels configured to receive ambient air at about atmospheric pressure. The ambient air cooling system may have a tip static pressure to ambient pressure ratio of at least 0.5, and in at least one embodiment, may include a tip static pressure to ambient pressure ratio of between about 0.5 and about 3.0. The cooling system may also be configured such that an under root slot chamber in the root is large to minimize supply air velocity. One or more cooling channels of the ambient air cooling system may terminate at an outlet at the tip such that the outlet is aligned with inner surfaces forming the at least one cooling channel in the airfoil to facilitate high mass flow.
International Nuclear Information System (INIS)
Starting with the space-time action of the transversally extended string, we derive its world-sheet action, which is that of a gravitational and gauge theory with matter fields on the world-sheet, with additional effects of the second fundamental quantity. (author)
Transverse myelitis spectrum disorders
Directory of Open Access Journals (Sweden)
Pandit Lekha
2009-01-01
Full Text Available Acute transverse myelitis (ATM is an inflammatory demyelinating disorder that affects the spinal cord focally resulting in motor sensory and autonomic dysfunction. Establishing the diagnosis of ATM is not as difficult as determining the possible etiology. There is a difference in the perception of ATM seen in the West as compared to developing countries. In the West multiple sclerosis (MS is the most common inflammatory disorder of the central nervous system. An attack of ATM may be the beginning of MS. However, this may not be the case in developing countries where MS is uncommon. Most often transverse myelitis is monophasic and at best represents a site-restricted form of acute disseminated encephalomyelitis (ADEM. Traditionally the combination of optic neuritis and ATM, occurring as a monophasic illness would have been called as neuromyelitis optica (NMO. Changing concepts in the definition of NMO and the discovery of a biomarker, neuromyelitis optica immunoglobulin (NMO_IgG, has changed the way relapsing autoimmune disorders are being perceived currently. A variety of idiopathic inflammatory disorders such as Japanese form of optic spinal MS, recurrent myelitis, and recurrent optic neuritis have been brought under the umbrella of neuromyelitis spectrum disorders because of the association with NMO-IgG. Complete transverse myelitis accompanied by longitudinally extensive transverse myelitis which is seronegative for this biomarker has also been reported from several countries including Japan, Australia, and India. Thus, ATM is a heterogeneous disorder with a varied clinical spectrum, etiology, and outcome.
Three dimensional (3d) transverse oscillation vector velocity ultrasound imaging
DEFF Research Database (Denmark)
2013-01-01
An ultrasound imaging system (300) includes a transducer array (302) with a two- dimensional array of transducer elements configured to transmit an ultrasound signal and receive echoes, transmit circuitry (304) configured to control the transducer array to transmit the ultrasound signal so as to...... the same received set of two dimensional echoes form part of the imaging system...
Transverse testicular ectopia.
Yıldız, Abdullah; Yiğiter, Murat; Oral, Akgün; Bakan, Vedat
2014-02-01
Described herein are six cases of transverse testicular ectopia. All patients who underwent orchidopexy at the one pediatric surgical unit between October 2001 and January 2008 were evaluated. The medical records of all patients diagnosed with transverse testicular ectopia were evaluated retrospectively. Five patients (84%) were admitted with a symptomatic right inguinal hernia and empty scrotum on the left side. Only one child (16%) had left-sided hernia and right non-palpable testis (age ranged from 1 month to 3 years). Four patients (66%) were diagnosed in the operating theatre and the last two (33%) on inguinal ultrasound preoperatively. Magnetic resonance imaging was also performed in the last patient. Herniorrhaphy with fixation of the ectopic gonad to the opposite hemiscrotum through a transseptal incision was performed in all patients. Postoperative complications were not observed. PMID:24548194
Transverse polarization in ; production
Indian Academy of Sciences (India)
Saurabh D Rindani
2007-11-01
With the use of transverse polarization (TP), a CP-odd and T-odd observable can be constructed when the final-state particles are self-conjugate. In the case of production, this observable can be used to probe a certain effective four-point + - CP-violating coupling, not accessible without TP. Effective CP-violating coupling does not contribute to this observable. A similar observable in production can be used to probe + - four-point couplings.
International Nuclear Information System (INIS)
The distribution of h1(x) of quark transverse polarization can be measured by Deep Inelastic Scattering using Collins effect as quark polarimeter. We propose to calibrate this polarimeter in e+e- → 2 jets. We give an explanation of single spin asymmetries in inclusive meson production based on the Collins effect. We propose a proportionality between the electric dipole moment of the nucleon on its tensor charge. (authors)
Transverse myelitis spectrum disorders
Pandit Lekha
2009-01-01
Acute transverse myelitis (ATM) is an inflammatory demyelinating disorder that affects the spinal cord focally resulting in motor sensory and autonomic dysfunction. Establishing the diagnosis of ATM is not as difficult as determining the possible etiology. There is a difference in the perception of ATM seen in the West as compared to developing countries. In the West multiple sclerosis (MS) is the most common inflammatory disorder of the central nervous system. An attack of ATM may be the beg...
Transverse Spin Physics: Recent Developments
Yuan, Feng
2009-01-01
Transverse-spin physics has been very active and rapidly developing in the last few years. In this talk, I will briefly summarize recent theoretical developments, focusing on the associated QCD dynamics in transverse spin physics.
Transverse tomography and radiotherapy
International Nuclear Information System (INIS)
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.)
Characteristics of transverse waves in chromospheric mottles
Energy Technology Data Exchange (ETDEWEB)
Kuridze, D.; Mathioudakis, M.; Jess, D. B.; Keenan, F. P. [Astrophysics Research Center, School of Mathematics and Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Verth, G.; Erdélyi, R. [Solar Physics and Space Plasma Research Center (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Morton, R. J. [Mathematics and Information Science, Northumbria University, Camden Street, Newcastle Upon Tyne NE1 8ST (United Kingdom); Christian, D. J., E-mail: dkuridze01@qub.ac.uk [Department of Physics and Astronomy, California State University, Northridge, CA 91330 (United States)
2013-12-10
Using data obtained by the high temporal and spatial resolution Rapid Oscillations in the Solar Atmosphere instrument on the Dunn Solar Telescope, we investigate at an unprecedented level of detail transverse oscillations in chromospheric fine structures near the solar disk center. The oscillations are interpreted in terms of propagating and standing magnetohydrodynamic kink waves. Wave characteristics including the maximum transverse velocity amplitude and the phase speed are measured as a function of distance along the structure's length. Solar magnetoseismology is applied to these measured parameters to obtain diagnostic information on key plasma parameters (e.g., magnetic field, density, temperature, flow speed) of these localized waveguides. The magnetic field strength of the mottle along the ∼2 Mm length is found to decrease by a factor of 12, while the local plasma density scale height is ∼280 ± 80 km.
Neutron Transversity at Jefferson Lab
Energy Technology Data Exchange (ETDEWEB)
Jian-Ping Chen; Xiaodong Jiang; Jen-chieh Peng; Lingyan Zhu
2005-09-07
Nucleon transversity and single transverse spin asymmetries have been the recent focus of large efforts by both theorists and experimentalists. On-going and planned experiments from HERMES, COMPASS and RHIC are mostly on the proton or the deuteron. Presented here is a planned measurement of the neutron transversity and single target spin asymmetries at Jefferson Lab in Hall A using a transversely polarized {sup 3}He target. Also presented are the results and plans of other neutron transverse spin experiments at Jefferson Lab. Finally, the factorization for semi-inclusive DIS studies at Jefferson Lab is discussed.
On the Transverse Invariant for Bindings of Open Books
Vela-Vick, David Shea
2011-01-01
Let $T \\subset (Y,\\xi)$ be a transverse knot which is the binding of some open book, $(T,\\pi )$, for the ambient contact manifold $(Y,\\xi)$. In this paper, we show that the transverse invariant $\\hat{\\mathscr{T}(T) \\in \\widehat{HFK}(−Y,K)$, defined in P. Lisca, P. Ozsváth, A. I. Stipsicz & Z. Szabó, "Heegaard Floer invariants of Legendrian knots in contact three-manifolds," J. Eur. Math. Soc. (JEMS) 11 (2009), no. 6, 1307–1363, MR 2557137, Zbl pre05641376, is nonvanishing for such...
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.
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.
Seismic Tomography Around the Eastern Edge of the Alps From Ambient-Noise-Based Rayleigh Waves
Zigone, Dimitri; Fuchs, Florian; Kolinsky, Petr; Gröschl, Gidera; Apoloner, Maria-Theresia; Qorbani, Ehsan; Schippkus, Sven; Löberich, Eric; Bokelmann, Götz; AlpArray Working Group
2016-04-01
Inspecting ambient noise Green's functions is an excellent tool for monitoring the quality of seismic data, and for swiftly detecting changes in the configuration of a seismological station. Those Green's functions readily provide stable information about structural variations near the Earth's surface. We apply the technique to a network consisting of about 40 broadband stations in the area of the Easternmost Alps, in particular those operated by the University of Vienna (AlpArrayAustria) and the Vienna University of Technology. Those data are used to estimate Green's functions between station pairs; the Green's function consist mainly of surface waves, and we use them to investigate crustal structure near the Eastern edge of the Alps. To obtain better signal-to-noise ratios in the noise correlation functions, we adopt a procedure using short time windows (2 hr). Energy tests are performed on the data to remove effects of transient sources and instrumental problems. The resulting 9-component correlation tensor is used to make travel time measurements on the vertical, radial and transverse components. Those measurements can be used to evaluate dispersion using frequency-time analysis for periods between 5-30 seconds. After rejecting paths without sufficient signal-to-noise ratio, we invert the velocity measurements using the Barmin et al. (2001) approach on a 10 km grid size. The obtained group velocity maps reveal complex structures with clear velocity contrasts between sedimentary basins and crystalline rocks. The Bohemian Massif and the Northern Calcareous Alps are associated with fast-velocity bodies. By contrast, the Vienna Basin presents clear low-velocity zones with group velocities down to 2 km/s at period of 7 s. The group velocities are then inverted to 3D images of shear wave speeds using the linear inversion method of Herrmann (2013). The results highlight the complex crustal structure and complement earthquake tomography studies in the region. Updated
Huang Jian-Xin; Song Min-Feng; Li Zhang; Liu Peng; Chen Rou-Xi; He Ji-Huan; Wang Shu-Qiang
2015-01-01
Transverse vibration of an axially moving slender fiber of viscoelastic fluid is studied. The governing equations are derived under the assumptions of onedimensional steady and incompressible flow and linear Euler-Bernoulli bar. Effect of the moving velocity of the liquid fiber on natural frequencies is discussed, and the critical velocities of moving fibers are derived, below which transverse vibration is exponentially damped.
Particle-in-cell simulations of the critical ionization velocity effect in finite size clouds
Moghaddam-Taaheri, E.; Lu, G.; Goertz, C. K.; Nishikawa, K. - I.
1994-01-01
The critical ionization velocity (CIV) mechanism in a finite size cloud is studied with a series of electrostatic particle-in-cell simulations. It is observed that an initial seed ionization, produced by non-CIV mechanisms, generates a cross-field ion beam which excites a modified beam-plasma instability (MBPI) with frequency in the range of the lower hybrid frequency. The excited waves accelerate electrons along the magnetic field up to the ion drift energy that exceeds the ionization energy of the neutral atoms. The heated electrons in turn enhance the ion beam by electron-neutral impact ionization, which establishes a positive feedback loop in maintaining the CIV process. It is also found that the efficiency of the CIV mechanism depends on the finite size of the gas cloud in the following ways: (1) Along the ambient magnetic field the finite size of the cloud, L (sub parallel), restricts the growth of the fastest growing mode, with a wavelength lambda (sub m parallel), of the MBPI. The parallel electron heating at wave saturation scales approximately as (L (sub parallel)/lambda (sub m parallel)) (exp 1/2); (2) Momentum coupling between the cloud and the ambient plasma via the Alfven waves occurs as a result of the finite size of the cloud in the direction perpendicular to both the ambient magnetic field and the neutral drift. This reduces exponentially with time the relative drift between the ambient plasma and the neutrals. The timescale is inversely proportional to the Alfven velocity. (3) The transvers e charge separation field across the cloud was found to result in the modulation of the beam velocity which reduces the parallel heating of electrons and increases the transverse acceleration of electrons. (4) Some energetic electrons are lost from the cloud along the magnetic field at a rate characterized by the acoustic velocity, instead of the electron thermal velocity. The loss of energetic electrons from the cloud seems to be larger in the direction of
A STATISTICAL STUDY OF TRANSVERSE OSCILLATIONS IN A QUIESCENT PROMINENCE
Energy Technology Data Exchange (ETDEWEB)
Hillier, A. [Kwasan and Hida Observatories, Kyoto University, Kyoto 607-8471 (Japan); Morton, R. J. [Mathematics and Information Science, Northumbria University, Pandon Building, Camden Street, Newcastle upon Tyne NE1 8ST (United Kingdom); Erdélyi, R., E-mail: andrew@kwasan.kyoto-u.ac.jp [Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)
2013-12-20
The launch of the Hinode satellite has allowed for seeing-free observations at high-resolution and high-cadence making it well suited to study the dynamics of quiescent prominences. In recent years it has become clear that quiescent prominences support small-amplitude transverse oscillations, however, sample sizes are usually too small for general conclusions to be drawn. We remedy this by providing a statistical study of transverse oscillations in vertical prominence threads. Over a 4 hr period of observations it was possible to measure the properties of 3436 waves, finding periods from 50 to 6000 s with typical velocity amplitudes ranging between 0.2 and 23 km s{sup –1}. The large number of observed waves allows the determination of the frequency dependence of the wave properties and derivation of the velocity power spectrum for the transverse waves. For frequencies less than 7 mHz, the frequency dependence of the velocity power is consistent with the velocity power spectra generated from observations of the horizontal motions of magnetic elements in the photosphere, suggesting that the prominence transverse waves are driven by photospheric motions. However, at higher frequencies the two distributions significantly diverge, with relatively more power found at higher frequencies in the prominence oscillations. These results highlight that waves over a large frequency range are ubiquitous in prominences, and that a significant amount of the wave energy is found at higher frequency.
Transverse Wobbling in $^{135}$Pr
Matta, J T; Li, W; Frauendorf, S; Ayangeakaa, A D; Patel, D; Schlax, K W; Palit, R; Saha, S; Sethi, J; Trivedi, T; Ghugre, S S; Raut, R; Sinha, A K; Janssens, R V F; Zhu, S; Carpenter, M P; Lauritsen, T; Seweryniak, D; Chiara, C J; Kondev, F G; Hartley, D J; Petrache, C M; Mukhopadhyay, S; Lakshmi, D Vijaya; Raju, M Kumar; Rao, P V Madhusudhana; Tandel, S K; Ray, S; Dönau, F
2015-01-01
A pair of transverse wobbling bands has been observed in the nucleus $^{135}$Pr. The wobbling is characterized by $\\Delta I$ =1, E2 transitions between the bands, and a decrease in the wobbling energy confirms its transverse nature. Additionally, a transition from transverse wobbling to a three-quasiparticle band comprised of strong magnetic dipole transitions is observed. These observations conform well to results from calculations with the Tilted Axis Cranking (TAC) model and the Quasiparticle Triaxial Rotor (QTR) Model.
Transverse wobbling in ^{135}pr.
Matta, J T; Garg, U; Li, W; Frauendorf, S; Ayangeakaa, A D; Patel, D; Schlax, K W; Palit, R; Saha, S; Sethi, J; Trivedi, T; Ghugre, S S; Raut, R; Sinha, A K; Janssens, R V F; Zhu, S; Carpenter, M P; Lauritsen, T; Seweryniak, D; Chiara, C J; Kondev, F G; Hartley, D J; Petrache, C M; Mukhopadhyay, S; Lakshmi, D Vijaya; Raju, M Kumar; Madhusudhana Rao, P V; Tandel, S K; Ray, S; Dönau, F
2015-02-27
A pair of transverse wobbling bands is observed in the nucleus ^{135}Pr. The wobbling is characterized by ΔI=1, E2 transitions between the bands, and a decrease in the wobbling energy confirms its transverse nature. Additionally, a transition from transverse wobbling to a three-quasiparticle band comprised of strong magnetic dipole transitions is observed. These observations conform well to results from calculations with the tilted axis cranking model and the quasiparticle rotor model. PMID:25768759
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 for the...
Pediatric transverse myelitis.
Absoud, Michael; Greenberg, Benjamin M; Lim, Ming; Lotze, Tim; Thomas, Terrence; Deiva, Kumaran
2016-08-30
Pediatric acute transverse myelitis (ATM) is an immune-mediated CNS disorder and contributes to 20% of children experiencing a first acquired demyelinating syndrome (ADS). ATM must be differentiated from other presentations of myelopathy and may be the first presentation of relapsing ADS such as neuromyelitis optica (NMO) or multiple sclerosis (MS). The tenets of the diagnostic criteria for ATM established by the Transverse Myelitis Consortium Working Group can generally be applied in children; however, a clear sensory level may not be evident in some. MRI lesions are often centrally located with high T2 signal intensity involving gray and neighboring white matter. Longitudinally extensive ATM occurs in the majority. Asymptomatic lesions on brain MRI are seen in more than one-third and predict MS or NMO. The role of antibodies such as myelin oligodendrocyte glycoprotein in monophasic and relapsing ATM and their significance in therapeutic approaches remain unclear. ATM is a potentially devastating condition with variable outcome and presents significant cumulative demands on health and social care resources. Children generally have a better outcome than adults, with one-half making a complete recovery by 2 years. There is need for standardization of clinical assessment and investigation protocols to enable international collaborative studies to delineate prognostic factors for disability and relapse. There are no robust controlled trials in children or adults to inform optimal treatment of ATM, with one study currently open to recruitment. This review provides an overview of current knowledge of clinical features, investigative workup, pathogenesis, and management of ATM and suggests future directions. PMID:27572861
Microstructural characterization of carbon steels using ultrasonic velocity measurements
Vera Lúcia de Araújo Freitas; Antonio Almeida Silva; Edgard de Macedo Silva; de Albuquerque, Victor Hugo C.; João Manuel Ribeiro da Silva Tavares
2009-01-01
Non-destructive techniques are suitable alternatives for analysis and microstructural characterization of steels#8217; phases. Based on this, this work aims to analyze the behavior of longitudinal and transverse ultrasonic velocities in three different types of AISI steels: 1006, 1080 and quenched 1045. These materials were selected due to their distinct microstructures: ferrite, pearlite and martensite, respectively. By measuring sound velocities for both longitudinal and transversal waves, ...
Ramsey interaction with transverse decay
Institute of Scientific and Technical Information of China (English)
Xucheng Wang; Huadong Cheng; Liang Liu
2012-01-01
The Ramsey fringe contrast of a pulsed optically pumped cold atom clock is strongly affected by the transverse decay of the atomic sample.This letter calculates the Ramsey fringe with focus on transverse decay,and analyzes the Ramsey fringe contrast with different transverse decay rates.By fitting the experimental data,we obtain the transverse decay rate in a cold atom sample at an approximate value of 30.5 s-1,which is much smaller than that in a cell.
Cross-correlations of ambient noise recorded by accelerometers.
Rábade García, S. E.; Ramirez-Guzman, L.
2014-12-01
We investigate the ambient noise cross-correlations obtained by using properly corrected accelerometric recordings, and determine velocity structure in central Mexico based on a dispersion analysis. The data used comprise ten months of continuous recordings - from April 2013 to January 2014 - of ambient seismic noise at stations operated by the National Seismological Service of Mexico and the Engineering Strong Ground Motion Network of the National Autonomous University of Mexico (UNAM). The vertical component of ambient noise was base-line corrected, filtered, and properly integrated before extracting Green's functions (GF), which were compared successfully against GF obtained using recordings from broadband velocity sensors. In order to obtain dispersion curves, we estimated group and phase velocities applying the FTAN analysis technique and obtained s-wave velocity profiles at selected regions. We conclude and highlight that the use of widely deployed accelerographs to conduct regional studies using ambient noise tomography is feasible
An In-vivo investigation of transverse flow estimation
DEFF Research Database (Denmark)
Udesen, Jesper; Jensen, Jørgen Arendt
2004-01-01
Conventional ultrasound scanners are restricted to display the blood velocity component in the ultrasound beam direction. By introducing a laterally oscillating field, signals are created from which the transverse velocity component can be estimated. This paper presents velocity and volume flow...... estimates obtained from flow phantom and in-vivo measurements at 90° relative to the ultrasound beam axis. The flow phantom experiment setup consists of a SMI140 flow phantom connected to a CompuFlow1000 programmable flow pump, which generates a flow similarly to that in the femoral artery. A B-K medical...
Transverse Spin Physics at HERMES
Elschenbroich, U.; G. Schnell; Seidl, R.; collaboration, for the HERMES
2004-01-01
Single-spin asymmetries in semi-inclusive pion production are measured by the HERMES experiment for the first time, with a transversely polarised hydrogen target. Two different sine-dependencies are extracted which can be related to the quark distributions transversity h_1(x) and the Sivers function f_1T^perp(x).
Transverse Spin Physics at HERMES
Hillenbrand, A.; collaboration, for the HERMES
2006-01-01
HERMES has measured azimuthal single-spin asymmetries of charged pions produced in deep-inelastic scattering of positrons on a transversely polarised hydrogen target. The presented azimuthal moments provide access to two yet unknown quark distribution functions, the transversity distribution function \\delta q and the Sivers function f_{1T}^{perp}.
An improved estimation and focusing scheme for vector velocity estimation
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt; Munk, Peter
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...
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...
Antunes, Dalila; Bernardo, Fátima; Palma-Oliveira, José-Manuel
2011-01-01
Na aplicação da Psicologia à área do AMBIENTE importa em primeiro lugar definir o que se entende, neste contexto, por ambiente. O conceito é entendido como toda a envolvente que rodeia o ser humano. Referimo-nos pois ao espaço físico e aos estímulos que nele existem (som, ar, paisagem…), dirigindo-se a Psicologia do Ambiente ao estudo e intervenção sobre a forma como o ambiente influencia o indivíduo ou grupos, e sobre o modo como o comportamento dos indivíduos e grupos influenciam o ambiente...
Transverse Neutrino Polarization in $\
Sobkow, W
2000-01-01
In this paper a scenario admitting the participation of right-handed $S_{R}$ and left-handed $S_{L}$ scalar couplings in addition to the left-handed standard $(V, A)_{L}$ couplings in the muonic neutrino-electron elastic scattering is considered. Muon-neutrinos can come from pion-decay. We consider this process at the level of the four-fermion point (contact) interaction. Muon-neutrinos are assumed to be massive and to be Dirac fermions. We assume also that the incoming neutrinos are polarized. The formula for the laboratory differential cross section (in the limit of vanishing neutrino mass) in which the non-standard contributions coming from the interference between the left-handed vector $V_{L}$ and right-handed $S_{R}$ scalar couplings appear is given. These are the transverse components of the incoming neutrino polarization, both T-odd and T-even. The non-zero values of such observables would be the proof of the participation of the right-handed neutrinos in a pure leptonic process. As far as T-odd trans...
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...
Relativistic Transverse Gravitational Redshift
Mayer, A. F.
2012-12-01
The parametrized post-Newtonian (PPN) formalism is a tool for quantitative analysis of the weak gravitational field based on the field equations of general relativity. This formalism and its ten parameters provide the practical theoretical foundation for the evaluation of empirical data produced by space-based missions designed to map and better understand the gravitational field (e.g., GRAIL, GRACE, GOCE). Accordingly, mission data is interpreted in the context of the canonical PPN formalism; unexpected, anomalous data are explained as similarly unexpected but apparently real physical phenomena, which may be characterized as ``gravitational anomalies," or by various sources contributing to the total error budget. Another possibility, which is typically not considered, is a small modeling error in canonical general relativity. The concept of the idealized point-mass spherical equipotential surface, which originates with Newton's law of gravity, is preserved in Einstein's synthesis of special relativity with accelerated reference frames in the form of the field equations. It was not previously realized that the fundamental principles of relativity invalidate this concept and with it the idea that the gravitational field is conservative (i.e., zero net work is done on any closed path). The ideal radial free fall of a material body from arbitrarily-large range to a point on such an equipotential surface (S) determines a unique escape-velocity vector of magnitude v collinear to the acceleration vector of magnitude g at this point. For two such points on S separated by angle dφ , the Equivalence Principle implies distinct reference frames experiencing inertial acceleration of identical magnitude g in different directions in space. The complete equivalence of these inertially-accelerated frames to their analogous frames at rest on S requires evaluation at instantaneous velocity v relative to a local inertial observer. Because these velocity vectors are not parallel, a
Relative Framing of Transverse knots
Chernov, Vladimir
2001-01-01
It is well-known that a knot in a contact manifold $(M,C)$ transverse to a trivialized contact structure possesses the natural framing given by the first of the trivialization vectors along the knot. If the Euler class $e_C\\in H^2(M)$ of $C$ is nonzero, then $C$ is nontrvivializable and the natural framing of transverse knots does not exist. We construct a new framing-type invariant of transverse knots called relative framing. It is defined for all tight $C$, all closed irreducible atoroidal ...
New technology - demonstration of a vector velocity technique
DEFF Research Database (Denmark)
Møller Hansen, Peter; Pedersen, Mads M; Hansen, Kristoffer L;
2011-01-01
With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60-70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa...
Prognosis of Acute Transverse Myelitis
J Gordon Millichap; John J Millichap
2014-01-01
Investigators at Children's Hospital of Chongqing Medical University, China, reviewed children diagnosed with acute transverse myelitis (ATM) between 1995 and 2008 and selected 39 patients diagnosed according to the new Johns Hopkins Consortium criteria.
Precision Measuring of Velocities via the Relativistic Doppler Effect
Ozernoy, Leonid M.
1997-01-01
Just as the ordinary Doppler effect serves as a tool to measure radial velocities of celestial objects, so can the relativistic Doppler effect be implemented to measure a combination of radial and transverse velocities by using recent improvements in observing techniques. A key element that makes a further use of this combination feasible is the periodicity in changes of the orbital velocity direction for the source. Two cases are considered: (i) a binary star; and (ii) a solitary star with t...
Energy Technology Data Exchange (ETDEWEB)
Cantillon-Murphy, P., E-mail: padraig@mit.ed [Division of Gastroenterology, Brigham and Women' s Hospital, Boston, MA (United States); Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA (United States); Wald, L.L., E-mail: wald@nmr.mgh.harvard.ed [MGH-HST Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States); Adalsteinsson, E., E-mail: elfar@mit.ed [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA (United States); MGH-HST Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States); Zahn, M., E-mail: zahn@mit.ed [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA (United States)
2010-09-15
In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, {tau}. As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, {Omega}, in rad s{sup -1}. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid's temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4 and 7 {sup o}C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid's temperature in the MRI environment which is characterized by a large DC field, B{sub 0}. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B{sub 0}. Results are presented for the expected temperature increase in small tumors ({approx}1cm radius) over an appropriate range of magnetic fluid concentrations (0.002-0.01 solid volume fraction) and nanoparticle radii (1-10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful the goal of this work is to examine, by means of analysis and simulation, the concept of interactive fluid magnetization using the dynamic behavior of superparamagnetic iron oxide nanoparticle suspensions in the MRI environment. In addition to the usual magnetic fields associated with MRI, a rotating magnetic field is applied transverse to the main B{sub 0} field of the MRI. Additional or modified magnetic fields have been previously proposed for hyperthermia and targeted drug delivery within MRI
International Nuclear Information System (INIS)
In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, τ. As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, Ω, in rad s-1. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid's temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4 and 7 oC above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid's temperature in the MRI environment which is characterized by a large DC field, B0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B0. Results are presented for the expected temperature increase in small tumors (∼1cm radius) over an appropriate range of magnetic fluid concentrations (0.002-0.01 solid volume fraction) and nanoparticle radii (1-10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful the goal of this work is to examine, by means of analysis and simulation, the concept of interactive fluid magnetization using the dynamic behavior of superparamagnetic iron oxide nanoparticle suspensions in the MRI environment. In addition to the usual magnetic fields associated with MRI, a rotating magnetic field is applied transverse to the main B0 field of the MRI. Additional or modified magnetic fields have been previously proposed for hyperthermia and targeted drug delivery within MRI. Analytical predictions and numerical simulations of the
Operational characteristics and power scaling of a transverse ﬂow transversely excited CW CO2 laser
Indian Academy of Sciences (India)
Jai Khare; R Sreedhar; C P Paul; T Reghu; A K Nath
2003-01-01
Transverse ﬂow transversely excited (TFTE) CO2 lasers are easily scalable to multikilowatt 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 power was not increasing when the discharge volume and the gas volumetric ﬂow were increased by increasing the electrode separation keeping the gas ﬂow velocity constant. The discharge voltage too remained almost constant with the change of electrode separation at the same gas ﬂow velocity. This necessitated revision of the scaling laws for designing this type of high power CO2 laser. Experimental results of laser performance for different electrode separations are discussed and the modiﬁcations in the scaling laws are presented.
Lu, Jie
2016-06-01
In this work, we report analytical results on transverse domain wall (TDW) statics and field-driven dynamics in quasi-one-dimensional biaxial nanowires under arbitrary uniform transverse magnetic fields (TMFs) based on the Landau-Lifshitz-Gilbert equation. Without axial driving fields, the static TDW should be symmetric about its center while twisted in its azimuthal angle distribution. By decoupling polar and azimuthal degrees of freedom, an approximate solution is provided which reproduces these features to a great extent. When an axial driving field is applied, the dynamical behavior of a TDW is viewed as the response of its static profile to external excitations. By means of the asymptotic expansion method, the TDW velocity in the traveling-wave mode is obtained, which provides the extent and boundary of the "velocity-enhancement" effect of TMFs on TDWs in biaxial nanowires. Finally, numerical simulations are performed and strongly support our analytics.
TRANSVERSE MIXING IN A TRAPEZOIDAL COMPOUND OPEN CHANNEL
Institute of Scientific and Technical Information of China (English)
ZENG Yu-hong; HUAI Wen-xin; GUYMER I
2008-01-01
Transverse mixing characteristics of solute in the open channel flow can provide useful information for river environmental management. The lateral mixing coefficient is a crucial parameter for reproducing the transverse mixing either by numerical simulation or by analytical prediction. Since the solute mixing can be greatly affected by the lateral variations in water depth, mixing coefficient should be determined in each sub-section (i.e., the main channel, side slope and flood plain) separately. In this article, the transverse mixing in a symmetric trapezoidal compound channel was studied based on laboratory measurement of longitudinal and transverse velocity components and lateral distribution of solute concentration. The lateral mixing coefficient was estimated by adopting different Schmidt numbers in different sub-sections divided according to the developing trend of the eddy viscosity, and finally a piecewise linear profile of mixing coefficient was adopted to analytically predict the transverse solute concentration. The comparison between the analytically predicted data and the measuring solute concentration proved that this is an effective way to estimate the lateral mixing in the open channel flow with lateral variations in water depth.
Ambient Noise Tomography of the British Isles
Nicolson, H. J.; Curtis, A.; Baptie, B.
2009-12-01
In recent years, surface wave tomography using empirical Green’s functions computed via the ambient noise interferometry method has become an established approach to lithospheric imaging problems. To date, ambient noise tomography has been successfully applied to seismometer arrays in the United States, Australia, Iceland, China, South Africa, Europe and the Tibetan Plateau. The basis of the ambient seismic interferometry method is that, by cross-correlating noise data between two seismic stations and stacking over a long enough time period, one can approximate the Green’s Function that would have been recorded at one of the stations if the other had actually been a source. Consequently, one of the main advantages of ambient noise interferometry is that traditional seismic sources such as earthquakes or ballistics are not required; therefore it is ideal for application to seismically quiescent areas such as the British Isles. The British Isles are an archipelago located adjacent to the Eurasian continental shelf in a typically intra-plate setting, formed by a complex amalgamation of several terranes. These range from Laurentian north of the Highland Boundary fault to Avalonian south of the Iapetus Suture and evidence of the regions turbulent geological past can be inferred from its lithospheric structure. Previous studies of the structure of the British Isles considered relatively few seismic stations and/or were limited to using offshore shots, quarry blasts or teleseismic earthquakes as seismic energy sources. We have applied the ambient noise tomography method to noise data recorded on approximately 100 broadband and short period seismometers, including many new stations, in the British Isles and mainland Europe. This dense coverage of the British Isles allows us to image the crust and upper mantle velocity structure with a horizontal resolution in the region of 100km across the North Sea and 30km in the mainland United Kingdom. Here we present the first
Spin Physics and Transverse Structure
Mulders, P J
2015-01-01
Spin is a welcome complication in the study of partonic structure that has led to new insights, even if theoretically and experimentally not all dust has settled, in particular on quark flavor dependence and gluon spin. At the same time it opened new questions on angular momentum and effects of transverse structure. In this talk the focus is on the role of the transverse momenta of partons. Like for collinear parton distribution functions (PDFs), we are also in the case of transverse momentum dependent (TMD) PDFs, talking about forward matrix elements. TMD PDFs (or in short TMDs) extend collinear PDFs with only spin-spin correlations to PDFs that include spin-momentum correlations, including also time-reversal-odd (T-odd) correlations, relevant for the description of single spin asymmetries. In this way TMDs open up new ways of studying the spin structure. Their operator structure within QCD, however, is more complex leading to various ways of breaking of universality.
Simulations of High-Velocity Clouds. I. Hydrodynamics and High-Velocity High Ions
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 th...
La Transversal Cafetera por Caldas
Duque Escobar, Gonzalo
2014-01-01
Dada la necesidad de una transversal férrea para resolver las falencias estructurales del transporte de carga colombiano, con la construcción del nuevo Túnel Cumanday bimodal y doble cruzando la Cordillera Central por Caldas, la nueva Transversal Cafetera podría diseñarse con pendiente máxima del 6% y velocidad de 80 km/h, y convertirse en complemento al paso por la Línea, y en el soporte de un corredor logístico que integraría la región andina de Colombia, al detonar con el ferrocarril senda...
Cosmology in Weyl Transverse Gravity
Oda, Ichiro
2016-01-01
We study the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology in the Weyl-transverse (WTDiff) gravity in a general space-time dimension. The WTDiff gravity is invariant under both the local Weyl (conformal) transformation and the volume preserving diffeormorphisms (transverse diffeomorphisms) and is believed to be equivalent to general relativity at least at the classical level (perhaps, even in the quantum regime). It is explicitly shown by solving the equations of motion that the FLRW metric is a classical solution in the WTDiff gravity only when the spatial metric is flat, that is, the Euclidean space, and the lapse function is a nontrivial function of the scale factor.
Acute transverse myelitis : MR characteristics.
Directory of Open Access Journals (Sweden)
Murthy J
1999-10-01
Full Text Available Magnetic resonance imaging findings in 13 patients with acute transverse myelitis are reviewed. In 12 cases centrally located high intensity signal extending over few spinal segments was noted. The lesion occupied more than two thirds of the cord′s cross-sectional area in 8 patients. Central dot sign was noted in 7 patients. Variable cord enlargement was seen in 5 patients. Contrast study in one patient showed peripheral enhancement. The MR characteristics that help in differentiating transverse myelitis from spinal form of multiple sclerosis are discussed.
Directory of Open Access Journals (Sweden)
Huang Jian-Xin
2015-01-01
Full Text Available Transverse vibration of an axially moving slender fiber of viscoelastic fluid is studied. The governing equations are derived under the assumptions of onedimensional steady and incompressible flow and linear Euler-Bernoulli bar. Effect of the moving velocity of the liquid fiber on natural frequencies is discussed, and the critical velocities of moving fibers are derived, below which transverse vibration is exponentially damped.
Dihadron Fragmentation Functions and Transversity
Radici, Marco; Bacchetta, Alessandro
2014-01-01
We present preliminary results for an updated extraction of the transversity parton distribution based on the analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets in collinear factorization. Data for proton and deuteron targets by HERMES and COMPASS allow for a flavor separation of the valence components of transversity, while di-hadron fragmentation functions are taken from the semi-inclusive production of two pion pairs in back-to-back jets in $e^+ e^-$ annihilation. The latter data from Belle have been reanalyzed using the replica method and a more realistic estimate of the uncertainties on the chiral-odd interference fragmentation function has been obtained. After encoding this piece of information into the deep-inelastic scattering cross section, the transversity has been re-extracted by using the most recent and more precise COMPASS data for proton target. This picture represents the current most realistic estimate of the uncertainties on our knowledge of tran...
Transverse Energy Production at RHIC
Li, Qun; Pang, Yang; Xu, Nu
1999-01-01
We study the mechanism of transverse energy (E_T) production in Au+Au collisions at RHIC. The time evolution starting from the initial energy loss to the final E_T production is closely examined in transport models. The relationship between the experimentally measured E_T distribution and the maximum energy density achieved is discussed.
Longitudinal and Transverse Nuclear Shadowing
Barone, V.; M.; Genovese
1996-01-01
Nuclear shadowing arises from multiple scattering of the hadronic fluctuations of the virtual photon in a nucleus. We predict different longitudinal and transverse shadowing and an A-dependence of R which can be up to a 50% effect. The possibility of detecting nuclear effects on R at HERA is discussed.
Directory of Open Access Journals (Sweden)
Lorna Matarrita Román
2012-11-01
Full Text Available The purpose of this research was to analyze whether the use of technological resources may be feasible in the implementation of the environmental culture cross-cutting factor for sustainable development, which focuses on environmental issues related to the contents of the Science study program for the seventh year of the basic general education. The research design is qualitative with a dominant approach and uses some quantitative elements specifically in the design of instruments and some data analysis techniques. The type of study was developed with a multi-method approach; a trend that has been shaping a research style which integrates various methods in a single design. For this, we identified the didactic strategies and their relationship to both, technology and the environmental axis for sustainable development, used by six Science teachers of the 7th grade, in public institutions of the province of Heredia, Central Valley, Costa Rica, as well as the opinion of 20 students from that same grade. The main results include the opinions of the students, who showed a considerable interest in classes where technological resources are used. However, teachers do not show great interest or positive opinions on this matter; in addition, they are not well trained on the use of technological resources. It was also identified that the teaching personal who participated in the study do not develop this curricular axis.
Recibido 19 de junio de 2012 • Corregido 16 de setiembre de 2012 • Aceptado 07 de noviembre de 2012
El propósito de esta investigación fue analizar si, en la implementación del eje transversal cultural ambiental para el desarrollo sostenible, que enfatiza en problemáticas ambientales relacionadas con los contenidos del programa de Ciencias de séptimo año de la Educación Básica, puede ser factible la utilización de recursos tecnológicos. El diseño de la investigación fue cualitativo con enfoque dominante
Okamoto, Takenori J; De Pontieu, Bart; Uitenbroek, Han; Van Doorsselaere, Tom; Yokoyama, Takaaki
2015-01-01
Transverse magnetohydrodynamic (MHD) waves have been shown to be ubiquitous in the solar atmosphere and can in principle carry sufficient energy to generate and maintain the Sun's million-degree outer atmosphere or corona. However, direct evidence of the dissipation process of these waves and subsequent heating has not yet been directly observed. Here we report on high spatial, temporal, and spectral resolution observations of a solar prominence that show a compelling signature of so-called resonant absorption, a long hypothesized mechanism to efficiently convert and dissipate transverse wave energy into heat. Aside from coherence in the transverse direction, our observations show telltale phase differences around 180 degrees between transverse motions in the plane-of-sky and line-of-sight velocities of the oscillating fine structures or threads, and also suggest significant heating from chromospheric to higher temperatures. Comparison with advanced numerical simulations support a scenario in which transverse...
O direito ao meio ambiente sadio: a proteção pela Corte Interamericana de Direitos Humanos
Eneida Orbage de Britto Taquary
2013-01-01
O artigo tem por objetivo analisar a proteção do meio ambiente sadio no âmbito da Corte Interamericana de direitos Humanos. São analisadas as decisões da Corte que protege de forma transversal o direito ao meio ambiente, quando tutela a vida, a saúde e a integridade corporal.
P-wave signatures and parameterization of transversely isotropic media: An overview
Energy Technology Data Exchange (ETDEWEB)
Tsvankin, I.
1994-07-01
Progress in seismic inversion and processing in anisotropic media depends on our ability to relate different seismic signatures to the anisotropic parameters. While the conventional notation (stiffness coefficients) is suitable for forward modeling, it is inconvenient in developing analytic insight into the influence of anisotropy on wave propagation. The author gives a consistent description of P-wave signatures in transversely isotropic media with arbitrary strength of the anisotropy, using the notation suggested by Thomsen (1986). The influence of transverse isotropy on P-wave propagation is shown to be practically independent of the vertical S-wave velocity V{sub S0}, even in models with strong velocity variations. Therefore, the contribution of transverse isotropy to P-wave kinematic and dynamic signatures is controlled by just two anisotropic parameters, {epsilon} and {delta}, with the vertical velocity V{sub P0} being no more than a scaling coefficient in homogeneous models.
A New Method for Estimation of Velocity Vectors
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt; Munk, Peter
1998-01-01
The paper describes a new method for determining the velocity vector of a remotely sensed object using either sound or electromagnetic radiation. The movement of the object is determined from a field with spatial oscillations in both the axial direction of the transducer and in one or two...... signal influenced by transverse motion. Such a transverse modulation can be generated by using apodization on individual transducer array elements together with a special focusing scheme. A method for making such a field is presented along with a suitable two-dimensional velocity estimator. An...
VELOCITY INDICATOR FOR EXTRUSION PRESS
Digney, F.J. Jr.; Bevilacqua, F.
1959-04-01
An indicator is presented for measuring the lowspeed velocity of an object in one direction where the object returns in the opposite direction at a high speed. The indicator comprises a drum having its axis of rotation transverse to the linear movement of the object and a tape wound upon the drum with its free end extending therefrom and adapted to be connected to the object. A constant torque is applied to the drum in a direction to wind the tape on the drum. The speed of the tape in the unwinding direction is indicated on a tachometer which is coupled through a shaft and clutch means to the drum only when the tape is unwinding.
Piezoelectric energy harvesting from transverse galloping of bluff bodies
Abdelkefi, A.; Hajj, M. R.; Nayfeh, A. H.
2013-01-01
The concept of harvesting energy from transverse galloping oscillations of a bluff body with different cross-section geometries is investigated. The energy is harvested by attaching a piezoelectric transducer to the transverse degree of freedom of the body. The power levels that can be generated from these vibrations and the variations of these levels with the load resistance, cross-section geometry, and freestream velocity are determined. A representative model that accounts for the transverse displacement of the bluff body and harvested voltage is presented. The quasi-steady approximation is used to model the aerodynamic loads. A linear analysis is performed to determine the effects of the electrical load resistance and the cross-section geometry on the onset of galloping, which is due to a Hopf bifurcation. The normal form of this bifurcation is derived to determine the type (supercritical or subcritical) of the instability and to characterize the effects of the linear and nonlinear parameters on the level of harvested power near the bifurcation. The results show that the electrical load resistance and the cross-section geometry affect the onset speed of galloping. The results also show that the maximum levels of harvested power are accompanied with minimum transverse displacement amplitudes for all considered (square, D, and triangular) cross-section geometries, which points to the need for performing a coupled analysis of the system.
Introduction to Transverse Beam Dynamics
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.
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.
Influence of speckle effect on doppler velocity measurement
Zheng, Zheng; Changming, Zhao; Haiyang, Zhang; Suhui, Yang; Dehua, Zhang; Xingyuan, Zheng; Hongzhi, Yang
2016-06-01
In a coherent Lidar system, velocity measurement of a target is achieved by measuring Doppler frequency shift between the echo and local oscillator (LO) signals. The measurement accuracy is proportional to the spectrum width of Doppler signal. Actually, the speckle effect caused by the scattering of laser from a target will broaden the Doppler signal's spectrum and bring uncertainty to the velocity measurement. In this paper, a theoretical model is proposed to predict the broadening of Doppler spectrum with respect to different target's surface and motion parameters. The velocity measurement uncertainty caused by the broadening of spectrum is analyzed. Based on the analysis, we design a coherent Lidar system to measure the velocity of the targets with different surface roughness and transverse velocities. The experimental results are in good agreement with theoretical analysis. It is found that the target's surface roughness and transverse velocity can significantly affect the spectrum width of Doppler signal. With the increase of surface roughness and transverse velocity, the measurement accuracy becomes worse. However, the influence of surface roughness becomes weaker when the spot size of laser beam on the target is smaller.
An investigation of ambient gameplay
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...
Transverse stability of Kawahara solitons
DEFF Research Database (Denmark)
Karpman, V.I.
1993-01-01
The transverse stability of the planar solitons described by the fifth-order Korteweg-de Vries equation (Kawahara solitons) is studied. It is shown that the planar solitons are unstable with respect to bending if the coefficient at the fifth-derivative term is positive and stable if it is negative....... This is in agreement with the dynamics of the two-dimensional Kawahara solitons....
Acute transverse myelitis : MR characteristics.
Murthy J; Reddy J; Meena A; Kaul S
1999-01-01
Magnetic resonance imaging findings in 13 patients with acute transverse myelitis are reviewed. In 12 cases centrally located high intensity signal extending over few spinal segments was noted. The lesion occupied more than two thirds of the cord′s cross-sectional area in 8 patients. Central dot sign was noted in 7 patients. Variable cord enlargement was seen in 5 patients. Contrast study in one patient showed peripheral enhancement. The MR characteristics that help in differentiating ...
Transverse Myelitis: An unusual association
Kalkan, Gokhan; Karaoglu, Abdulbaki; Vurucu, Sebahattin; Unay, Bulent; Gok, Faysal; Akin, Ridvan; Arslan, Mehmet Tayyip
2012-01-01
Transverse myelitis (TM) is an acute inflammation of spinal cord characterized by demyelination. Infectious, inflammatory and autoimmune etiologies constitute the most common etiologies of TM. It is believed that pathlogical changes in infection related cases occur due to altered immune response rather than direct effect of the infection. Methicillin resistant Staphylococcus aureus (MRSA) a well known agent of hospital and sometimes community acquired pneumonia leads to increased morbidity an...
Transverse Aortic Constriction in Mice
deAlmeida, Angela C.; van Oort, Ralph J.; Wehrens, Xander H. T.
2010-01-01
Transverse aortic constriction (TAC) in the mouse is a commonly used experimental model for pressure overload-induced cardiac hypertrophy and heart failure.1 TAC initially leads to compensated hypertrophy of the heart, which often is associated with a temporary enhancement of cardiac contractility. Over time, however, the response to the chronic hemodynamic overload becomes maladaptive, resulting in cardiac dilatation and heart failure.2 The murine TAC model was first validated by Rockman et ...
Pore Velocity Estimation Uncertainties
Devary, J. L.; Doctor, P. G.
1982-08-01
Geostatistical data analysis techniques were used to stochastically model the spatial variability of groundwater pore velocity in a potential waste repository site. Kriging algorithms were applied to Hanford Reservation data to estimate hydraulic conductivities, hydraulic head gradients, and pore velocities. A first-order Taylor series expansion for pore velocity was used to statistically combine hydraulic conductivity, hydraulic head gradient, and effective porosity surfaces and uncertainties to characterize the pore velocity uncertainty. Use of these techniques permits the estimation of pore velocity uncertainties when pore velocity measurements do not exist. Large pore velocity estimation uncertainties were found to be located in the region where the hydraulic head gradient relative uncertainty was maximal.
Ambient oxygen promotes tumorigenesis.
Directory of Open Access Journals (Sweden)
Ho Joong Sung
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.
Zuluaga Sánchez, Gloria Patricia
1998-01-01
El debate sobre mujer y medio ambiente es bastante nuevo y, por lo tanto, aun no hay consenso sobre como abordarlo, ni análisis muy profundos sobre la interacción de estas dos problemáticas tan complejas y que además atraviesan las demás temáticas. Con ello no se quiere negar el importante aporte que se ha hecho en tal sentido, por parte de colectividades y de algunas personas. Selene Herculano y Jacqueline Pitanguy (1993), mencionan que el medio ambiente no es una categoría específica y que ...
Ambientes de aprendizaje computacionales
Señas, Perla
2001-01-01
En el marco de las aplicaciones de la tecnología computacional a la educación se destaca de manera especial el trabajo sobre Ambientes de Aprendizaje. En él convergen tópicos relevantes de las Ciencias de la Computación y de la Educación. Se puede definir un Ambiente de Aprendizaje Computacional como un entorno integrado por un conjunto no homogéneo de elementos capaces de crear o recrear situaciones a partir de las cuales el alumno puede construir conocimiento y realizar aprendizajes y meta-...
Transversity distribution functions in the valon model
Alizadeh Yazdi, Z.; Taghavi-Shahri, F.; Arash, F.; Zomorrodian, M. E.
2014-05-01
We use the valon model to calculate the transversity distribution functions inside the nucleon. Transversity distributions indicate the probability to find partons with spin aligned (antialigned) to the transversely polarized nucleon. The results are in good agreement with all available experimental data and also global fits.
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.
Analysis of ultrasonic wave propagation in transversely isotropic austenitic welds
International Nuclear Information System (INIS)
Ultrasonic testing of austenitic welds is widely known to be difficult mainly due to the anisotropy and inhomogeneity of their elastic properties. This study investigates the physical phenomena of ultrasonic wave propagation and scattering in austenitic welds, modeled as homogeneous and transversely isotropic. The velocity and slowness surfaces are obtained for the transversely isotropic plane of austenitic welds, using the elasticity analysis. Also, the phenomena of wave generation, propagation and scattering in the same medium are simulated using the mass-spring lattice model. The numerical results show good qualitative agreement with the analytical results, and various waves in the numerical results are identified by comparing with the analytical results. Further development of this work will provide useful and practical results for the field ultrasonic testing of austenitic welds.
Plane wave propagation in transversely isotropic laser-excited solids
International Nuclear Information System (INIS)
This paper concentrates on the study of body harmonic wave propagation in an anisotropic laser-excited solid in the context of the model based on coupled equations for the displacement and atomic defect concentration fields. The complex secular equations for transversely isotropic solids are derived and discussed. It is found, in general, four types of dispersive waves, namely a quasi-longitudinal (QL), two quasi-transverse (QT) and a quasi-defect wave (N-mode) can propagate in these types of crystals. The different characteristics of waves like phase velocity, attenuation coefficient are obtained and presented graphically. It is demonstrated that there is an appreciable variation in case of the QL mode as compared with QT and N-modes. Some particular cases have also been discussed
Directory of Open Access Journals (Sweden)
Rafael Núñez-Lagos Roglá
2011-01-01
Full Text Available Se explican los conceptos fundamentales relacionados con la radiactividad y se utilizan para describir la radiactividad ambiental. Se explican también los isótopos de largo periodo y las principales familias radioactivas junto con la radiación cósmica y los radionucleidos cosmogénicos.
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 c...
Dynamic analysis of the mechanical systems vibrating transversally in transportation
Directory of Open Access Journals (Sweden)
A. Buchacz
2007-01-01
Full Text Available Purpose: Purpose of this paper is analysis and modelling of mechanical systems in transportation. Thecontemporary technical problems are lashed with high work demands such as high speeds of mechanisms, usinglower density materials, high precision of work, etc. The main objective of this thesis was the dynamical analysiswith taking into consideration the interaction between main motion and local vibrations during the model isloaded by transverse forces.Design/methodology/approach: Equations of motion were derived by classical methods, the Lagrangeequations with generalized coordinates and generalized velocities assumed as orthogonal projections ofindividual coordinates and velocities of the beam and manipulators to axes of the global inertial frame.Findings: Presented mathematical model of the transversally vibrating systems in planar transportation can beput to use to derivation of the dynamical flexibility of these systems, moreover those equations are the startingpoint to the analysis of complex systems. In particular we can use those equations to derivation of the substitutedynamical flexibility of multibody systems.Research limitations/implications: There were considered mechanical systems vibrating transversally in termsof plane motion. Next problem of dynamical analysis is the analysis of systems in non-planar transportation andsystems loaded by longitudinal forces.Practical implications: Results of this thesis can be put to use into all machines and mechanisms running intransportation such as wind power plants, high speed turbines, rotors, manipulators and in aerodynamics issues,etc. Some results ought to be modified and adopted to appropriate models.Originality/value: High requirements applying to parameters of work of machines and mechanisms are causedthe new research and new ways of modelling and analyzing those systems. One of these ways are presented inthis thesis. There was defined the transportation effect for models vibrating
Contribution to the study of transverse turbulent diffusion in streams
International Nuclear Information System (INIS)
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 Lx and a turbulent intensity √(u'2) is proposed: K = β.Lx.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)
Transversals in Non-Discrete Groups
Indian Academy of Sciences (India)
Ramji Lal; R P Shukla
2005-11-01
The concept of `topological right transversal' is introduced to study right transversals in topological groups. 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). It is also proved that if a topological right transversal $(S, T_S, T^S, \\circ)$ is such that $T_S=T^S$ is a locally compact Hausdorff topology on , then can be embedded as a right transversal of a closed subgroup in a Hausdorff topological group which is universal in some sense.
Projectile transverse motion and stability in electromagnetic induction launchers
Energy Technology Data Exchange (ETDEWEB)
Shokair, I.R.
1993-12-31
The transverse motion of a projectile in an electromagnetic induction launcher is considered. The equations of motion for translation and rotation are derived assuming a rigid projectile and a flyway restoring force per unit length that is proportional to the local displacement. Linearized transverse forces and torques due to energized coils are derived for displaced or tilted armature elements based on a first order perturbation method. The resulting equations of motion for a rigid projectile composed of multiple elements in a multi-coil launcher are analyzed as a coupled oscillator system of equations and a simple linear stability condition is derived. The equations of motion are incorporated into the 2-D Slingshot circuit code and numerical solutions for the transverse motion are obtained. For a launcher with a 10 cm bore radius with a 40 cm long solid armature, we find that stability is achieved with a restoring force (per unit length) constant of k {approx} 1 {times} 10{sup 8} N/m{sup 2}. For k = 1.5 {times} 10{sup 8} N/m{sup 2} and sample coil misalignment modeled as a sine wave of 1 mm amplitude at wavelengths of one or two meters, the projectile displacement grows to a maximum of 4 mm. This growth is due to resonance between the natural frequency of the projectile transverse motion and the coil displacement wavelength. This resonance does not persist because of the changing axial velocity. Random coil displacement is also found to cause roughly the same projectile displacement. For the maximum displacement a rough estimate of the transverse pressure is 50 bars. Results for a wound armature with uniform current density throughout show very similar displacements.
Czech Academy of Sciences Publication Activity Database
Růžek, Bohuslav; Valentová, L.; Gallovič, F.
2016-01-01
Roč. 173, - (2016). ISSN 0033-4553 Institutional support: RVO:67985530 Keywords : ambient noise * geological units * Bohemian Massif * velocity model Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.618, year: 2014
Transverse momentum bounds and scaling in the hydrodynamical model
Chaichian, Masud; Suhonen, E
1974-01-01
It is shown that the equation of state of an ideal relativistic gas, as applied in the hydrodynamical model, leads not only to deviations from scaling in longitudinal rapidity distributions, but also to an average transverse momentum increasing asymptotically as a power of the incident energy. To prevent such an increase, one must use the equation of state of an interacting gas, in which the velocity of sound becomes asymptotically equal to that of light. This then also restores scaling (up to logarithmic terms) in longitudinal rapidity. (25 refs).
Delaminations in composite plates under transverse impact loads - Experimental results
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.
Institute of Scientific and Technical Information of China (English)
FAN Jing-yu; ZHANG Yan; WANG Dao-zeng
2009-01-01
The vortex formation and entrainment characteristics for a round transverse jet in shallow water were experimentally investigated by means of a combination of LIF flow visualization and PIV measurement. A scarf vortex wrapped around the main body of the jet is formed in the near-wall region due to the interaction between the resulting wall jet and sufficiently shallow crossflow, with some more or less unsteady flow properties and with spreading ranges as functions of both the velocity ratio and the water depth within the near field. The entrainment of the ambient crossflow fluid into the jet main body is closely associated with the time-evolving features of the shear layer between the jet and surrounding fluid as well as the induced vortical structures near the wall. In the case of slight impingement upon the wall, the interaction between the jet shear layer and the weak, unstable scarf vortex gives rise to an appreciable local entrainment enhancement, confined in the near-wall region in the vicinity of the stagnation point. While in the case of intense impingement upon the wall, the well-organized and stable scarf vortex gives rise to a greatly enhanced entrainment and a greatly increased lateral spreading rate nearly throughout the overall near field as compared to the conventional wall jet. In addition, the entrainment of the ambient crossflow fluid by the scarf vortex in this case occurs largely on the surface of the unique spiral roller structure by itself due to the presence of smaller and unorganized eddies, and accordingly the scarf vortex is likely to keep its spiral roller structure steadily to a relatively great downstream distance within the near field.
Ambient Air Quality Data Inventory
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...
Ambient Air Quality Data Inventory
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...
NIF Ambient Vibration Measurements
International Nuclear Information System (INIS)
LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B
Ground motion in the presence of complex topography: Earthquake and ambient noise sources
Hartzell, Stephen; Meremonte, Mark; Ramírez-Guzmán, Leonardo; McNamara, Daniel
2014-01-01
To study the influence of topography on ground motion, eight seismic recorders were deployed for a period of one year over Poverty Ridge on the east side of the San Francisco Bay Area, California. This location is desirable because of its proximity to local earthquake sources and the significant topographic relief of the array (439 m). Topographic amplification is evaluated as a function of frequency using a variety of methods, including reference‐site‐based spectral ratios and single‐station horizontal‐to‐vertical spectral ratios using both shear waves from earthquakes and ambient noise. Field observations are compared with the predicted ground motion from an accurate digital model of the topography and a 3D local velocity model. Amplification factors from the theoretical calculations are consistent with observations. The fundamental resonance of the ridge is prominently observed in the spectra of data and synthetics; however, higher‐frequency peaks are also seen primarily for sources in line with the major axis of the ridge, perhaps indicating higher resonant modes. Excitations of lateral ribs off of the main ridge are also seen at frequencies consistent with their dimensions. The favored directions of resonance are shown to be transverse to the major axes of the topographic features.
Resolution enhancement of slam using transverse wave
International Nuclear Information System (INIS)
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.
Salud ambiental: conceptos y actividades
Ordóñez Gonzalo A.
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...
Transverse Laplacians for Substitution Tilings
Julien, Antoine
2009-01-01
Pearson and Bellissard recently built a spectral triple - the data of Riemanian noncommutative geometry - for ultrametric Cantor sets. They derived a family of Laplace-Beltrami like operators on those sets. Motivated by the applications to specific examples, we revisit their work for the transversals of tiling spaces, which are particular self-similar Cantor sets. We use Bratteli diagrams to encode the self-similarity, and Cuntz-Krieger algebras to implement it. We show that the abscissa of convergence of the zeta-function of the spectral triple gives indications on the exponent of complexity of the tiling. We determine completely the spectrum of the Laplace-Beltrami operators, give an explicit method of calculation for their eigenvalues, compute their Weyl asymptotics, and a Seeley equivalent for their heat kernels.
Gluonic Transversity from Lattice QCD
Detmold, W
2016-01-01
We present an exploratory study of the gluonic structure of the $\\phi$ meson using lattice QCD (LQCD). This includes the first investigation of gluonic transversity via the leading moment of the twist-two double-helicity-flip gluonic structure function $\\Delta(x,Q^2)$. This structure function only exists for targets of spin $J\\ge1$ and does not mix with quark distributions at leading twist, thereby providing a particularly clean probe of gluonic degrees of freedom. We also explore the gluonic analogue of the Soffer bound which relates the helicity flip and non-flip gluonic distributions, finding it to be saturated at the level of 80%. This work sets the stage for more complex LQCD studies of gluonic structure in the nucleon and in light nuclei where $\\Delta(x,Q^2)$ is an 'exotic glue' observable probing gluons in a nucleus not associated with individual nucleons.
Mesons on a transverse lattice
Dalley, S
2001-01-01
The meson eigenstates of the light-cone Hamiltonian in a coarse transverse lattice gauge theory are investigated. Building upon previous work in pure gauge theory, the Hamiltonian and its Fock space are expanded in powers of dynamical fields. In the leading approximation, the couplings appearing in the Hamiltonian are renormalised by demanding restoration of space-time symmetries broken by the cut-off. Additional requirements from chiral symmetry are discussed and difficulties in imposing them from first principles in the leading approximation are noted. A phenomenological calculation is then performed, in which chiral symmetry in spontaneously broken form is modelled by imposing the physical pion-rho mass splitting as a constraint. The light-cone wavefunctions of the resulting Hamiltonian are used to compute decay constants, form factors and quark momentum and spin distributions for the pion and rho mesons. Extensions beyond leading order, and the implications for first principles calculations, are briefly d...
Transverse Impedance of Ferrite Elements
Burov, A
2004-01-01
A specific feature of ferrites is that these materials behave either as metals or magneto-dielectrics, depending on the frequency range. Their magnetic permeability is a function of frequency as well. In this paper, the transverse impedance of a ferrite kicker is calculated. The method suggested in Ref. [1] is generalized here for ferrites. Namely, in [1] it is assumed that the electric field of the beam charge dipole is always perfectly shielded. In fact, this assumption requires the conductivity being high compared with the frequency. This is not necessarily true for the high frequencies of a proton single-bunch spectrum. That is why the dynamics of the electric shielding has to be taken into account for ferrite kickers. The generalized analytic result is applied for the ferrite MKE kickers at the CERN SPS, and a fairly good agreement with observations [2] is found.
Transverse Stress Fracture of the Proximal Patella
ATSUMI, SATORU; Arai, Yuji; Kato, Ko; Nishimura, Akinobu; Nakazora, Shigeto; Nakagawa, Shuji; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Sudo, Akihiro; Kubo, Toshikazu
2016-01-01
Abstract Among stress fractures associated with sports activities, patellar stress fracture is rare. Regarding patella stress fractures, so far only distal transverse or lateral longitudinal fractures have been reported, but there are no reports of transverse fractures occurring in the proximal patella. We describe an extremely rare case of transverse stress fracture of proximal patella in a 9-year-old athlete. A 9-year old boy, who participated in sports (sprints and Kendo) presented with le...
Transverse and longitudinal vibrations in amorphous silicon
Beltukov, Y. M.; De Fusco, C; Tanguy, A.; Parshin, D. A.
2015-01-01
We show that harmonic vibrations in amorphous silicon can be decomposed to transverse and longitudinal components in all frequency range even in the absence of the well defined wave vector ${\\bf q}$. For this purpose we define the transverse component of the eigenvector with given $\\omega$ as a component, which does not change the volumes of Voronoi cells around atoms. The longitudinal component is the remaining orthogonal component. We have found the longitudinal and transverse components of...
Large transverse momentum behavior of gauge theories
International Nuclear Information System (INIS)
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
Transverse Reinforcement in Reinforced Concrete Columns
Gramblička, Štefan; Veróny, Peter
2013-11-01
In the article we are dealing with the influence of transverse reinforcement to the resistance of a cross-section of the reinforced concrete columns and also with the effective detailing of the column reinforcement. We are verifying the correctness of design guides for detailing of transverse reinforcement. We are also taking into account the diameter of stirrups and its influence over transverse deformation of column.
Inhomogeneity and transverse voltage in superconductors
Segal, A.; Karpovski, M.; Gerber, A
2011-01-01
Voltages parallel and transverse to electric current in slightly inhomogeneous superconductors can contain components proportional to the field and temperature derivatives of the longitudinal and Hall resistivities. We show that these anomalous contributions can be the origin of the zero field and even-in-field transverse voltage occasionally observed at the superconductor to normal state transition. The same mechanism can also cause an anomaly in the odd-in-field transverse voltage interferi...
Distinguishing screening mechanisms with environment-dependent velocity statistics
Ivarsen, Magnus Fagernes; Llinares, Claudio; Mota, David F
2016-01-01
Alternative theories of gravity typically invoke an environment-dependent "screening mechanism" to allow phenomenologically interesting deviations from general relativity (GR) to manifest on larger scales, while reducing to GR on small scales. The observation of the transition from screened to unscreened behavior would be compelling evidence for beyond-GR physics. In this paper, we show that pairwise peculiar velocity statistics -- in particular the relative radial velocity dispersion, $\\sigma_\\parallel$ -- can be used to observe this transition when they are binned by some measure of halo environment. We establish this by measuring the radial velocity dispersion between pairs of halos in N-body simulations for 3 $f(R)$ gravity and 4 Symmetron models. We develop an estimator involving only line-of-sight velocities to show that this quantity is observable, and bin the results in halo mass, ambient density, and the "isolatedness" of halos. Ambient density is found to be the most relevant measure of environment;...
3-D Velocity Estimation for Two Planes in vivo
Holbek, Simon; Pihl, Michael Johannes; Ewertsen, Caroline; Bachmann, Michael Bachmann; Jensen, Jørgen Arendt
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 phantom with constant flow. This paper presents the first in vivo measurements of the 3-D velocity vector, which were obtained over 3 cardiac cycles in the common carotid artery of a 32-year-old healthy m...
Ultrarelativistic transverse momentum distribution of Tsallis statistics
Parvan, A S
2016-01-01
The analytical expression for the ultrarelativistic transverse momentum distribution of the Tsallis statistics was obtained. We found that the transverse momentum distribution of the Tsallis-factorized statistics, which is now largely used for the description of the experimental transverse momentum spectra of hadrons measured in $pp$ collisions at LHC and RHIC energies, in the ultrarelativistic case is equivalent to the transverse momentum distribution of the Tsallis statistics in the zeroth term approximation with transformation of the parameter $q$ to $1/q_{c}$.
Transversals in non-discrete groups
Lal, Ramji; Shukla, R. P.
2005-01-01
The concept of `topological right transversal' is introduced to study right transversals in topological groups. Given any right quasigroup $S$ with a Tychonoff topology $T$, 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 subgroup (not necessarily closed). It is also proved that if a topological right transversal $(S, T_{S}, T^{S}, \\circ)$ is such that $T_{S} = T^{S}$ is a locally compact Hau...
Transversity of quarks in a nucleon
Indian Academy of Sciences (India)
K Bora; D K Choudhury
2003-11-01
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 twist-two distribution function – gluons do not couple to it. Quarks in a nucleon/hadron are relativistically bound and transversity is a measure of the relativistic nature of bound quarks in a nucleon. In this work, we review some important aspects of this less familiar distribution function which has not been measured experimentally so far.
Variability and Velocity of Superluminal Sources
Cohen, M H; Homan, D C; Kellermann, K I; Lister, M L; Vermeulen, R C; Ros, E; Zensus, J A
2003-01-01
We investigate the relation between the Doppler factor determined from variations in total flux at 22 and 37 GHz, and the apparent transverse velocity determined from VLBA observations at 2 cm. The data are consistent with the relativistic beaming theory for compact radio sources, in that the distribution of beta_{app}/delta_{var}, for 30 quasars, is roughly consistent with a Monte Carlo simulation. The intrinsic temperature appears to be ~2x10^{10} K, close to the "equipartition value" calculated by Readhead (1994). We deduce the distribution of Lorentz factors for a group of 48 sources; the values range up to about gamma=40.
Coherent perfect absorption mediated enhancement of transverse spin in a gap plasmon guide
Mukherjee, Samyobrata
2016-01-01
We consider a symmetric gap plasmon guide (a folded Kretschmann configuration) supporting both symmeric and antisymmetric coupled surface plasmons. We calculate the transverse spin under illumination from both the sides like in coherent perfect absorption (CPA), whereby all the incident light can be absorbed to excite one of the modes of the structure. Significant enhancement in the transverse spin is shown to be possible when the CPA dip and the mode excitation are at the same frequency. The enhancement results from CPA-mediated total transfer of the incident light to either of the coupled modes and the associated large local fields. The transverse spin is localized in the structure since in the ambient dielectric there are only incident plane waves lacking any structure.
Transverse mixing in three-dimensional nonstationary anisotropic heterogeneous porous media
DEFF Research Database (Denmark)
Cirpka, Olaf; Chiogna, Gabriele; Rolle, Massimo;
2015-01-01
Groundwater plumes originating from continuously emitting sources are typically controlled by transverse mixing between the plume and reactants in the ambient solution. In two-dimensional domains, heterogeneity causes only weak enhancement of transverse mixing in steady-state flows. In three......-dimensional domains, more complex flow patterns are possible because streamlines can twist. In particular, spatially varying orientation of anisotropy can cause steady-state groundwater whirls. We analyze steady-state solute transport in three-dimensional locally isotropic heterogeneous porous media with blockwise...... anisotropic correlation structure, in which the principal directions of anisotropy differ from block to block. For this purpose, we propose a transport scheme that relies on advective transport along streamlines and transverse-dispersive mass exchange between them based on Voronoi tessellation. We compare...
Saura Carulla, Magdalena
2003-01-01
La arquitectura y la planificación son el resultado de una integración ponderada de conocimientos técnicos y una multiplicidad de aspectos relacionados con el conocimiento natural y social. En este trabajo el autor propone, desde el ámbito de las ciencias del medio ambiente, diversos planteamientos teóricos y prácticos relacionados con la arquitectura y el urbanismo. El conocimiento de la naturaleza de los sistemas naturales y de los sistemas ecosociales permite al diseñador aplicar un marco ...
Canigiani, Franca
2016-01-01
L’ambiente è il quadro di vita, la casa comune, il patrimonio di base delle società umane – scriveva un indimenticabile maestro della geografia italiana: Giuseppe Barbieri. Due gli avvenimenti che nel 2015 hanno segnato il passo dell’umanità sulla strada di una più matura coscienza ambientale, fino a comprendere che è necessario e urgente prendersi cura della Terra: primo, la pubblicazione della lettera enciclica di papa Francesco, Laudato si’ sulla cura della casa comune, straordinario saggi...
Riva Juan, Mª del Carmen; López Ribas, David
1996-01-01
Los productos organohalogenados son muy utilizados por la industria y su presencia en el medio ambiente está siendo controlada. En los últimos años se han desarrollado varias técnicas de detección, siendo desde finales de los 80 los AOX (adsorbable organic halogens) uno de los parámetros sobre los que se han realizado más estudios. En muchos paises de la Unión Europea y en E.E.U.U. de América, la presencia de compuestos organohalogenados en aguas continentales y suelos está legislada indicand...
Angular velocity discrimination
Kaiser, Mary K.
1990-01-01
Three experiments designed to investigate the ability of naive observers to discriminate rotational velocities of two simultaneously viewed objects are described. Rotations are constrained to occur about the x and y axes, resulting in linear two-dimensional image trajectories. The results indicate that observers can discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.
Energy Technology Data Exchange (ETDEWEB)
Dizene, R. [Universite des Sciences et de la Technologie Houari Boumediene, USTHB, Institut de Genie Mecanique, IGM, El-Alia (Algeria); Charbonnier, J.M. [Aeronautics/Aerospace Dept. Von Karman Institute for Fluid Dynamics, Sint-Genesius-Rode (Belgium); Dorignac, E. [Ecole Nationale Superieure de Mecanique et d' Aerotechnique (ENSMA), Lab. d' Etudes Thermiques ENSMA, 86 - Poitiers (France); Leblanc, R. [Poitiers Univ., 86 (France). Laboratoire d' Etudes Aerodynamiques, UMR 6609
2000-03-01
The results of the investigation of the interaction of a row of jets with a compressible cross flow are compared with their counterpart obtained in incompressible regime. The comparison reported here focuses on the flow field resulting from the interaction above and at the wall. The velocity and temperature fields are measured respectively by laser Doppler velocimetry and thermocouple probes. The wall temperature distributions are measured using an infrared camera. The experiments are performed for cross flow flow Mach numbers of 0.72 and 0.1 for respectively the compressible and incompressible regimes with almost the same injection rate (R=0.50 and 0.6). Significant differences are noticed between the two flow fields in particular on the vertical development of the jets in the cross flow and on the turbulent diffusion. The jet penetration is found to be higher in the compressible regime with less interaction between the jets. The comparison also shows that the wall heat transfer modifications induced by the jets are less pronounced in the compressible case a result of the higher penetration of the jets. These results show that Neither the mass flux ratio nor the momentum ratio are good candidates for extrapolation of the cooling efficiency from the incompressible case to the real compressible case as encountered in the practical applications. (authors)
International Nuclear Information System (INIS)
Ever since pulsars were found to have significant proper motions, the origin of the velocities has been an intriguing question. The more recent finding that the velocities display a significant correlation with the derived magnetic moments of the pulsars has made the origin of the velocities appear even more mysterious. Arguments are given to show that the above correlation is not causal, but accidental. Pulsar velocities are determined by their binary histories and not governed in any way by their magnetic fields. 10 references, 4 figures
About measuring velocity dispersions
Fellhauer, M.
A lot of our knowledge about the dynamics and total masses of pressure dominated stellar systems relies on measuring the internal velocity disper- sion of the system. We assume virial equilibrium and that we are able to measure only the bound stars of the system without any contamination. This article shows how likely it is to measure the correct velocity dispersion in reality. It will show that as long as we have small samples of velocity mea- surements the distribution of possible outcomes can be very large and as soon as we have a source of error the velocity dispersion can wrong by several standard deviations especially in large samples.
Experiments on the critical ionization velocity interaction in weak magnetic fields
International Nuclear Information System (INIS)
The critical ionization velocity interaction is studied experimentally in a configuration with a magnetized plasma stream colliding with a stationary neutral gas cloud. Experiments are performed both with a transverse and longitudinal magnetic field. It is found that in both cases the critical ionization velocity effect either disappears or becomes too small to be distinguishable among classical collisional processes. (author)
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.
Transverse invariant higher-spin fields
Energy Technology Data Exchange (ETDEWEB)
Skvortsov, E.D. [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute, Leninsky prospect 53, 119991 Moscow (Russian Federation)], E-mail: eugene.skvortsov@gmail.com; Vasiliev, M.A. [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute, Leninsky prospect 53, 119991 Moscow (Russian Federation)], E-mail: vasiliev@lpi.ru
2008-06-26
It is shown that a symmetric massless bosonic higher-spin field can be described by a traceless tensor field with reduced (transverse) gauge invariance. The Hamiltonian analysis of the transverse gauge invariant higher-spin models is used to control a number of degrees of freedom.
Interference Fragmentation Functions and the Nucleon's Transversity
Jaffe, R. L.; Jin, Xuemin; Tang, Jian
1997-01-01
We introduce twist-two quark interference fragmentation functions in helicity density matrix formalism and study their physical implications. We show how the nucleon's transversity distribution can be probed through the final state interaction between two mesons ($\\pi^+\\pi^-$, $K\\bar K$, or $\\pi K$) produced in the current fragmentation region in deep inelastic scattering on a transversely polarized nucleon.
A GENERALIZED TRANSVERSALITY IN GLOBAL ANALYSIS
Institute of Scientific and Technical Information of China (English)
Ma Jipu
2004-01-01
@@ E. Zeidler in [10] mentions that transversality is certainly one of the most important concepts of modern mathematics, which provided an answer to the question: when is the preimage of a manifold a manifold. This is the celebrated transversality theorem, which has been applied widely to differential topology and dynamic system in [1,2] and [3].
Transverse Force on Quarks in DIS
Burkardt, Matthias
2015-01-01
Generalized Parton Distributions (GPDs) provide information on the distribution of quarks in impact paarmeter space. For transversely polarized nucleons, these impact parameter distributions are transversely distorted and this deviation from axial symmetry leads on average to a net transverse force from the spectators on the active quark in a DIS experiment. %The strength of that force can be related to twist-3 PDFs. This force when acting along the whole trajectory of the active quark leads to a transverse single-spin asymmetries. For a longitudinally polarized nucleon target, the transverse force implies a torque acting on the quark Orbital Angular Momentum (OAM). The resulting change in OAM as the quark leaves the target equals the difference between the Jaffe-Manohar and Ji OAMs.
Growth of transverse coherence in SASE FELs
International Nuclear Information System (INIS)
We introduce the correlation function between the electric field at two different points in the transverse plane as a parameter to quantify the degree of transverse coherence. We also propose a more realistic model for the initialization of the radiation in computer codes used to study SASE FELs. We make these modifications in the code TDA and use it to study the growth of transverse coherence as a function of electron beam size, beam current and transverse emittance. Our results show explicitly that the onset of full transverse coherence in SASE takes place much before the power saturates. With the more realistic model the onset of the exponential growth regime is delayed, and to get a given power from the FEL one needs a longer undulator than would be predicted by the original TDA code
Growth of transverse coherence in SASE FELs
Kumar, V
2000-01-01
We introduce the correlation function between the electric field at two different points in the transverse plane as a parameter to quantify the degree of transverse coherence. We also propose a more realistic model for the initialization of the radiation in computer codes used to study SASE FELs. We make these modifications in the code TDA and use it to study the growth of transverse coherence as a function of electron beam size, beam current and transverse emittance. Our results show explicitly that the onset of full transverse coherence in SASE takes place much before the power saturates. With the more realistic model the onset of the exponential growth regime is delayed, and to get a given power from the FEL one needs a longer undulator than would be predicted by the original TDA code.
Transverse and longitudinal vibrations in amorphous silicon
Beltukov, Y. M.; Fusco, C.; Tanguy, A.; Parshin, D. A.
2015-12-01
We show that harmonic vibrations in amorphous silicon can be decomposed to transverse and longitudinal components in all frequency range even in the absence of the well defined wave vector q. For this purpose we define the transverse component of the eigenvector with given ω as a component, which does not change the volumes of Voronoi cells around atoms. The longitudinal component is the remaining orthogonal component. We have found the longitudinal and transverse components of the vibrational density of states for numerical model of amorphous silicon. The vibrations are mostly transverse below 7 THz and above 15 THz. In the frequency interval in between the vibrations have a longitudinal nature. Just this sudden transformation of vibrations at 7 THz from almost transverse to almost longitudinal ones explains the prominent peak in the diffusivity of the amorphous silicon just above 7 THz.
International Nuclear Information System (INIS)
In this thesis aspects of the structure of the nucleus 19F are discussed as a result of transverse electron-scattering experiments, with emphasis on the ground state. The magnetization distribution of this state has been obtained from the measurement of electrons scattered from 19F at backward angles. An introduction to the electron-scattering formalism is presented briefly together with the interpretation of electron-scattering results in terms of the nuclear shell model. The experimental apparatus for the measurement of electron scattering through an angle of 1800 is described. This instrumentation has been installed in the low-energy facility (LEF) at NIKHEF-K. Simultaneously with the study of the magnetic ground state distribution of 19F, also excited states of this nucleus up to an energy of 4.4 MeV have been investigated, mainly from data obtained in the EMIN station. Also for these states, the shell-model calculations have been the guide to determine their structure. (Auth.)
Transverse mode coupling in RHIC
Energy Technology Data Exchange (ETDEWEB)
Raka, E.
1990-02-21
In the Proceedings of the Workshop on the RHIC Performance, it was stated that the transverse mode coupling instability, posed a potential intensity limitation for protons. This was based on the expression I{sub b} = 4(E{sub t}/qe) Q{sub s} 4 {radical}{pi} {sigma} {ell}/(Im (Z{sub {perpendicular}}) < {beta}{sub {perpendicular}} > R 3) where E{sub t} is the total energy, q the charge state, Q{sub s} the synchrotron tune, < {beta}{sub {perpendicular}} > the average beta function, R the machine radius, and {sigma}{sub {ell}} the rms bunch length of a Gaussian distribution in longitudinal phase space. For a < {beta}{sub {perpendicular}} > of 55 m and 10{sup 11} protons/bunch, the allowed impedance Z{sub {perpendicular}} for protons at injection, where Q{sub s} = 0.11 {times} 10{sup {minus}3}, would be less than 1.2 M{Omega}/m. The purpose of this report is to discuss the consequences of two factors that were omitted in this equation, which comes from the ZAP program, to RHIC. These are the space charge impedance and the incoherent tune spread of the beam.
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.)
MRI in acute transverse myelopathy
International Nuclear Information System (INIS)
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.)
Capecchi, Sara; 10.4204/EPTCS.19.7
2010-01-01
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.
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.
Wakker, Bart P.; Woerden, Hugo van; Oswalt, Terry D.; Gilmore, Gerard
2013-01-01
The high-velocity clouds (HVCs) are gaseous objects that do not partake in differential galactic rotation, but instead have anomalous velocities. They trace energetic processes on the interface between the interstellar material in the Galactic disk and intergalactic space. Three different processes
Critical ionization velocity interaction
International Nuclear Information System (INIS)
Different problems of current interest regarding the critical ionization velocity (CIV) phenomenon are discussed. The article is divided into five sections corresponding to different aspects of the interaction: velocity, magnetic field strength, geometry, neutral gas density, and time duration. In each section, experiments and theories - microscopic and macroscopic - are discussed
Artru, Xavier
2014-01-01
The tunneling ionization of a hydrogen atom excited in the presence of a static electric field is investigated for the case where, before being extracted, the electron has an orbital angular momentum L perpendicular to the field E. The escaping electron has a nonzero mean transverse velocity in the direction of E cross . This asymmetry is similar to the Collins effect in the fragmentation into hadrons of a transversely polarized quark. In addition, the linear Stark effect make and oscillate in time. The degree of asymmetry is calculated at leading order in E for an initial state of maximum transverse . The conditions for the observation of this asymmetry are discussed.
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
angiography (MRA) by comparing in vivo measurements of stroke volume. Eleven healthy volunteers were included in this prospective study. From the obtained data sets recorded with the 2 modalities, vector velocity sequences were constructed and stroke volume calculated. Angle of insonation was approximately 90...... 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...... indicate that reliable vector velocity estimates can be obtained in vivo using the presented angle-independent 2-D vector velocity method. The TO method can be a useful alternative to conventional Doppler systems by avoiding the angle artifact, thus giving quantitative velocity information....
Reforma constitucional y ambiente
Directory of Open Access Journals (Sweden)
Teodoro Bustamante
2013-09-01
Full Text Available América Latina está atravesada por una ola de reformas constitucionales. Sus causas, las expectativas que ellas despiertan, los riesgos que se han asociado al proceso de lucha política en su entorno, son temas de un análisis fundamentalmente político; pero hay algunos aspectos en los cuales ese debate tiene una directa repercusión sobre el tema ambiental. En el caso del Ecuador, esto se refleja en el hecho de que una de las innovaciones que se proponen, se refieren a una nueva forma de abordar los temas ambientales, básicamente se establecen Derechos de la Naturaleza.
MEIO AMBIENTE E DESENVOLVIMENTO
Suely Salgueiro Chacon; Daniel Rodriguez de Carvalho Pinheiro; Francisco Correia de Oliveira; Elizabeth Castelo Branco de Souza
2009-01-01
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 d...
Estrategia Ambiental Provincial
Directory of Open Access Journals (Sweden)
Angel A. Alfonso
2010-10-01
Full Text Available El trabajo que se presenta constituye la Estrategia Ambiental Provincial, elaborada por un Colectivo de Autores formado por especialistas e investigadores de la Delegación Provincial del CITMA en Matanzas. Esta Estrategia ha sido onfeccionada según el marco de las orientaciones contenidas en la Estrategia Nacional y aborda los principales problemas medio ambientales presentados de forma jerárquica así como los instrumentos para la materialización de dicha Estrategia. El Resultado, primero de su tipo en el país, se elaboró con la aplicación de técnicas y métodos de la investigación científica, tales como: Método de Expertos, tormentas de ideas, método de los grupos nominales, método Delphi, método de votación directa o ponderada, Saaty etc. Los antecedentes principales que permitieron la obtención del Resultado fueron el Diagnóstico de la Situación Ambiental de la Provincia, las Estrategias Ambientales de las principales Empresas o Sectores de la Economía del territorio y los Diagnósticos de las Cuencas Hidrográficas. Se contó además con la colaboración de especialistas de otras instituciones provinciales tales como el Centro Provincial de Higiene y Epidemiología, Instituto de Recursos Hidráulicos, Empresa Nacional de Proyectos Agropecuarios del MINAGRI. El resultado fue constituído como política en el territorio en el mes de abril de 1998 con su aprobación por el Consejo de la Administración Provincial.
Salim, S.; Gould, A.
2000-12-01
Full-Sky Astrometric Mapping Explorer (FAME) belongs to a new generation of astrometry satellites and will probe the surrounding space some 20 times deeper than its predecessor Hipparcos. As a result we will acquire precise knowledge of 5 out of 6 components of phase-space for millions of stars. The remaining coordinate, radial velocity, will remain unknown. In this study, we look at how the knowledge of radial velocity affects the determination of the structure of the Galaxy, and its gravitational potential. We therefore propose a radial velocity survey of FAME stars, and discuss its feasibility and technical requirements.
TRANSVERSE SPIN AT PHENIX AND FUTURE PLANS.
Energy Technology Data Exchange (ETDEWEB)
MAKDISI,Y. (FOR THE PHENIX COLLABORATION)
2005-01-28
The PHENIX experiment took data with transversely polarized proton beams in 2001-2002 and measured the transverse single spin asymmetries in inclusive neutral pion and non-identified charge hadrons at midrapidity and {radical} s = 200 GeV. The data near X{sub F} {approx} 0 cover a transverse momentum range from 0.5 to 5.0 GeV/c. The observed asymmetries are consistent with zero with good statistical accuracy. This paper presents the current work in light of earlier measurements at lower energies in this kinematic region and the future plans of the PHENIX detector.
Ferroelectric Cathodes in Transverse Magnetic Fields
International Nuclear Information System (INIS)
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
Validating Firewalls in Mobile Ambients
DEFF Research Database (Denmark)
Nielson, Flemming; Nielson, Hanne Riis; Hansen, René Rydhof; Jensen, J. G.
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...
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?
Directory of Open Access Journals (Sweden)
Dani Martinez
2014-03-01
Full Text Available This paper proposes the use of an autonomous assistant mobile robot in order to monitor the environmental conditions of a large indoor area and develop an ambient intelligence application. The mobile robot uses single high performance embedded sensors in order to collect and geo-reference environmental information such as ambient temperature, air velocity and orientation and gas concentration. The data collected with the assistant mobile robot is analyzed in order to detect unusual measurements or discrepancies and develop focused corrective ambient actions. This paper shows an example of the measurements performed in a research facility which have enabled the detection and location of an uncomfortable temperature profile inside an office of the research facility. The ambient intelligent application has been developed by performing some localized ambient measurements that have been analyzed in order to propose some ambient actuations to correct the uncomfortable temperature profile.
The critical ionization velocity
International Nuclear Information System (INIS)
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)
Investigation of Slipstream Velocity
Crowley, J W , Jr
1925-01-01
These experiments were made at the request of the Bureau of Aeronautics, Navy Department, to investigate the velocity of the air in the slipstream in horizontal and climbing flight to determine the form of expression giving the slipstream velocity in terms of the airspeed of the airplane. The method used consisted in flying the airplane both on a level course and in climb at full throttle and measuring the slipstream velocity at seven points in the slipstream for the whole speed range of the airplane in both conditions. In general the results show that for both condition, horizontal and climbing flights, the slipstream velocity v subscript 3 and airspeed v can be represented by straight lines and consequently the equations are of the form: v subscript s = mv+b where m and b are constant. (author)
Nerve conduction velocity (NCV) is a test to see how fast electrical signals move through a nerve. ... surface electrodes are placed on the skin over nerves at different spots. Each patch gives off a ...
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.
The critical ionization velocity
International Nuclear Information System (INIS)
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. (Auth.)
Transverse Fresnel-Fizeau drag effects in strongly dispersive media
International Nuclear Information System (INIS)
A light beam normally incident upon an uniformly moving dielectric medium is, in general, subject to bendings due to a transverse Fresnel-Fizeau light drag effect. In most familiar dielectrics, the magnitude of this bending effect is very small and hard to detect. Yet, the effect can be dramatically enhanced in strongly dispersive media where slow group velocities in the m/s range have been recently observed taking advantage of the electromagnetically induced transparency effect. In addition to the usual downstream drag that takes place for positive group velocities, we discuss a significant anomalous upstream drag which is expected to occur for negative group velocities. Furthermore, for sufficiently fast speeds of the medium, higher-order dispersion terms are found to play an important role and to be responsible for light propagation along curved paths or the restoration of the time and space coherence of an incident noisy beam. The physics underlying this class of slow-light effects is thoroughly discussed
Van Essen, H.
2004-01-01
This paper addresses the problem of the separation of rotational and internal motion. It introduces the concept of average angular velocity as the moment of inertia weighted average of particle angular velocities. It extends and elucidates the concept of Jellinek and Li (1989) of separation of the energy of overall rotation in an arbitrary (non-linear) $N$-particle system. It generalizes the so called Koenig's theorem on the two parts of the kinetic energy (center of mass plus internal) to th...
Constituent models and large transverse momentum reactions
International Nuclear Information System (INIS)
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
Transversally periodic solitary gravity-capillary waves.
Milewski, Paul A; Wang, Zhan
2014-01-01
When both gravity and surface tension effects are present, surface solitary water waves are known to exist in both two- and three-dimensional infinitely deep fluids. We describe here solutions bridging these two cases: travelling waves which are localized in the propagation direction and periodic in the transverse direction. These transversally periodic gravity-capillary solitary waves are found to be of either elevation or depression type, tend to plane waves below a critical transverse period and tend to solitary lumps as the transverse period tends to infinity. The waves are found numerically in a Hamiltonian system for water waves simplified by a cubic truncation of the Dirichlet-to-Neumann operator. This approximation has been proved to be very accurate for both two- and three-dimensional computations of fully localized gravity-capillary solitary waves. The stability properties of these waves are then investigated via the time evolution of perturbed wave profiles. PMID:24399922
TRANSVERSAL SPACES AND FIXED POINT THEOREMS
Sinia N. Ješić; Milan R. Tasković; Nataša Babačev
2007-01-01
In this paper we define Transversal functional probabilistic spaces (upper and lower) as a natural extension of Metric spaces, Probabilistic metric spaces and Fuzzy metric spaces. Also, we formulate and prove some fixed and common fixed point theorems.
Transverse flow in thin superhydrophobic channels
Feuillebois, Francois; Vinogradova, Olga I
2010-01-01
We provide some general theoretical results to guide the optimization of transverse hydrodynamic phenomena in superhydrophobic channels. Our focus is on the canonical micro- and nanofluidic geometry of a parallel-plate channel with an arbitrary two-component (low-slip and high-slip) coarse texture, varying on scales larger than the channel thickness. By analyzing rigorous bounds on the permeability, over all possible patterns, we optimize the area fractions, slip lengths, geometry and orientation of the surface texture to maximize transverse flow. In the case of two aligned striped surfaces, very strong transverse flows are possible. Optimized superhydrophobic surfaces may find applications in passive microfluidic mixing and amplification of transverse electrokinetic phenomena.
Transverse myelitis associated with Mycoplasma pneumoniae infection.
MacFarlane, P I; Miller, V
1984-01-01
A case of acute transverse myelitis associated with respiratory infection by Mycoplasma pneumoniae is described. Circulating antibodies to myelin were detected suggesting that mycoplasma related neurological damage is mediated by producing an immunological myelopathy.
Delayed transverse radiation myelitis in esophageal carcinoma
International Nuclear Information System (INIS)
Objective: To investigate the prevention and treatment of delayed transverse myelitis caused by radiotherapy in patients with thoracic esophageal carcinoma. Methods: Radical radiotherapy had been given to five patients (female 3, male 2) with thoracic esophageal carcinoma with delayed transverse myelitis developed 7 to 30 months after radiotherapy without any local recurrence. The study was done in an attempt to describe the clinical symptoms and signs. Analysis of causes was done to seek possible means of treatment and prevention. Results: Once delayed transverse myelitis had happened, it was not possible to cure. In this group, four patients died 1-2 years after myelopathy had occurred, and one was alive with functional neurological loss. Conclusions: Delayed transverse myelitis is an uncommon and serious complication induced by irradiation. It is very difficult to manage and indicates a very poor prognosis. The authors recommend precise radiation design and prudent performance for prevention
Average transverse momentum quantities approaching the lightfront
Boer, Daniel
2014-01-01
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 transverse momenta, which conveys little information about the transverse momentum distributions of quarks and gluons inside hadrons. TMD factorization naturally suggests alternative definitions of such integrated quantities, using Bessel-weighting and rapidity cut-offs, with the conventional definitions as limiting cases. The regularized quantities are given in terms of integrals over the TMDs of interest that are well-defined and moreover have the advantage of being amenable to lattice evaluations.
Anisotropic Ambient Volume Shading.
Ament, Marco; Dachsbacher, Carsten
2016-01-01
We present a novel method to compute anisotropic shading for direct volume rendering to improve the perception of the orientation and shape of surface-like structures. We determine the scale-aware anisotropy of a shading point by analyzing its ambient region. We sample adjacent points with similar scalar values to perform a principal component analysis by computing the eigenvectors and eigenvalues of the covariance matrix. In particular, we estimate the tangent directions, which serve as the tangent frame for anisotropic bidirectional reflectance distribution functions. Moreover, we exploit the ratio of the eigenvalues to measure the magnitude of the anisotropy at each shading point. Altogether, this allows us to model a data-driven, smooth transition from isotropic to strongly anisotropic volume shading. In this way, the shape of volumetric features can be enhanced significantly by aligning specular highlights along the principal direction of anisotropy. Our algorithm is independent of the transfer function, which allows us to compute all shading parameters once and store them with the data set. We integrated our method in a GPU-based volume renderer, which offers interactive control of the transfer function, light source positions, and viewpoint. Our results demonstrate the benefit of anisotropic shading for visualization to achieve data-driven local illumination for improved perception compared to isotropic shading. PMID:26529745
Adjustable Fiber Optic Microwave Transversal Filters
Shadaram, Mehdi; Lutes, George F.; Logan, Ronald T.; Maleki, Lutfollah
1994-01-01
Microwave transversal filters implemented as adjustable tapped fiber optic delay lines developed. Main advantages of these filters (in comparison with conventional microwave transversal filters) are small size, light weight, no need for matching of radio-frequency impedances, no need for shielding against electromagnetic radiation at suboptical frequencies, no need for mechanical tuning, high stability of amplitude and phase, and active control of transfer functions. Weights of taps in fiber optic delay lines adjusted.
The transverse shape of the electron
Hoyer, Paul; Kurki, Samu
2009-01-01
We study the charge density, form factors and spin distributions of the electron induced by its |e \\gamma> light-front Fock state in impact parameter space. Only transversally compact Fock states contribute to the leading behavior of the Dirac and Pauli form factors as the momentum transfer tends to infinity. Power suppressed contributions are not compact, and distributions weighted by the transverse size have end-point contributions. The Fock state conserves the spin of the parent electron l...
Spin versus helicity in processes involving transversity
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 formalism...
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.
Subacute transverse myelitis with Lyme profile dissociation
Ajjan, Mohammed; Walid, M. Sami; Ulm, Arthur J.
2008-01-01
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 ...
Drag Reduction by Microvortexes in Transverse Microgrooves
Bao Wang; Jiadao Wang; Gang Zhou; Darong Chen
2014-01-01
A transverse microgrooved surface was employed here to reduce the surface drag force by creating a slippage in bottom layer in turbulent boundary layer. A detailed simulation and experimental investigation on drag reduction by transverse microgrooves were given. The computational fluid dynamics simulation, using RNG k-ε turbulent model, showed that the vortexes were formed in the grooves and they were a main reason for the drag reduction. On the upside of the vortex, the revolving direction w...
A Study of Large Transverse Momentum Phenomena
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...
Antolin, Patrick; De Pontieu, Bart; Uitenbroek, Han; Van Doorsselaere, Tom; Yokoyama, Takaaki
2015-01-01
Transverse magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere and may be responsible for generating the Sun's million-degree outer atmosphere. However, direct evidence of the dissipation process and heating from these waves remains elusive. Through advanced numerical simulations combined with appropriate forward modeling of a prominence flux tube, we provide the observational signatures of transverse MHD waves in prominence plasmas. We show that these signatures are characterized by thread-like substructure, strong transverse dynamical coherence, an out-of-phase difference between plane-of-the-sky motions and LOS velocities, and enhanced line broadening and heating around most of the flux tube. A complex combination between resonant absorption and Kelvin-Helmholtz instabilities (KHI) takes place in which the KHI extracts the energy from the resonant layer and dissipates it through vortices and current sheets, which rapidly degenerate into turbulence. An inward enlargement of the boundary i...
Electron velocity distributions near collisionless shocks
International Nuclear Information System (INIS)
Recent studies of the amount of electron heating and of the shapes of electron velocity distributions across shocks near the earth are reviewed. It is found that electron heating increases with increasing shock strength but is always less than the ion heating. The scale length of electron heating is also less than that for the ions. Electron velocity distributions show characteristic shapes which depend on the strength of the shocks. At the weaker shocks, electron heating is mostly perpendicular to the ambient magnetic field, bar B, and results in Gaussian-shaped velocity distributions at low-to-moderate energies. At the stronger shocks, parallel heating predominates resulting in flat-topped velocity distributions. A reasonable interpretation of these results indicates that at the weaker shocks electron heating is dominated by a tendency toward conservation of the magnetic moment. At the stronger fast-mode shocks, this heating is thought to be dominated by an acceleration parallel to bar B produced by the macroscopic shock electric field followed by beam driven plasma instabilities. Some contribution to the heating at the stronger shocks from conservation of the magnetic moment and cross-field current-driven instabilities cannot be ruled out. Although the heating at slow-mode shocks is also dominated by instabilities driven by magnetic field-aligned electron beams, their acceleration mechanism is not yet established
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.
International Nuclear Information System (INIS)
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
Visualization and analysis of jet oscillation under transverse acoustic perturbation
De La Cuadra, Patricio; Fabre, Benoit
2008-01-01
Schlieren flow visualizations of transverse oscillations of jets submitted to an acoustic perturbation are analyzed in this paper. The aim is to estimate the shape and the position of the median line of the jet. Two methods for image processing are proposed, based on complementary approaches : inter image and intra image analysis. Synthesized images of an oscillating jet are used to validate each method and compare their performances in the case of noisy pictures. Illustrations are then shown on real laminar and turbulent jets. The results obtained using both methods are very close, showing their reliability. Applications investigated in this paper are focused on the estimation of the convection velocity of perturbations along the jet, and the influence of the Reynolds number and of the channel geometry upstream the jet formation.
Transverse Vector Vertex Function and Transverse Ward-Takahashi Relations in QED
Institute of Scientific and Technical Information of China (English)
HE Han-Xin
2006-01-01
The transverse vector vertex function in momentum space in four-dimensional QED is derived in terms of a set of transverse Ward-Takahashi relations for the vector and the axial-vector vertices in the case of massless fermion.It is demonstrated explicitly that the transverse vector vertex function derived this way to one-loop order leads to the same result as one obtained in perturbation theory. This provides a basic approach to determine the transverse part of basic vertex function from the symmetry relations of the system.
An unstructured second-order Godunov method for transverse MHD
International Nuclear Information System (INIS)
The Godunov method and its higher-order extensions have been very successful in treating flows with shock waves in gas dynamics. These algorithms for the inviscid Euler equations are based on exact local solutions to the Riemann problem. They have the desirable properties of being able to describe shock waves and contact discontinuities with a width of only a few mesh points, while preserving monotonicity in the physical variables (i.e., they are non-oscillatory). The authors have extended the Godunov method to the MHD equations, in order to simulate plasmas with small viscosity and resistivity. In the case of the transverse MHD model (a 2D system in which all quantities vary in the x-y plane, with a magnetic field transverse to the flow, i.e., B = Bz(x,y)z, with flow velocity v = vx(x,y)x + vy(x,y)y), the Riemann problem can be solved exactly. They have developed a 2D code which uses unstructured adaptive triangular meshes, and which is based on a magnetic Riemann solver. This code is particularly suited to modeling realistic geometries. They describe applications of this code to implosive plasma phenomena, including plasma pinches. 4 refs
Panou, Areti; Paulssen, Hanneke; Hatzidimitriou, Panagiotis
2015-01-01
In this study we present phase velocity maps that were obtained from the cross-correlation analysis of ambient seismic noise recorded in the region of Greece.We used one year (2013) of ambient seismic data obtained from the vertical component of 64 broadband permanent seismological stations that are
A marginal theory for critical velocity ionization
International Nuclear Information System (INIS)
All space based tests of Alfven's CIV hypothesis to date may be described as marginal. That is, no large excess of ionization has been observed, but in many experiments, such as Porcupine, the observed ionization seems to exceed that which can be explained by charge exchange and other collisional processes. This talk will advance the theory that the coupling of momentum to the background plasma by new born ions is more limited than previously thought, and that this limiting will restrict the build up of excess ion density at any point in space. One may generalize CIV theory to state that the free energy available for transfer from new born ions to electrons and subsequently available for additional ionization, depends on the relative velocity between the ions and electrons bound to the magnetic. It will be shown that maintaining the highest possible relative velocity depends on coupling the momentum of new ions to the ambient plasma. It will also be argued that the ambient thermal current places more severe limits on momentum coupling than generally allowed by MHD
Aspectos computacionais do ambiente IMAGUS
Raabe, André Luís Alice; Giraffa, Lúcia Maria Martins
2000-01-01
Este artigo apresenta a descrição do ambiente IMAGUS enfatizando aspectos da implementação do protótipo do ambiente. O IMAGUS permite a construção de materiais com fins pedagógicos que se utilizam de vídeos acessado via Internet. O protótipo foi desenvolvido para validar a arquitetura proposta para o ambiente. São apresentadas as soluções a nível de modelagem e a implementação do protótipo baseada na utilização da interface Java Media Framework
In vivo validation of a blood vector velocity estimator with MR angiography
DEFF Research Database (Denmark)
Hansen, K.L.; Udesen, J.; Thomsen, C.;
2009-01-01
contrast angiography (MRA) by comparing in vivo measurements of stroke volume. Eleven healthy volunteers were included in this prospective study. From the obtained data sets recorded with the 2 modalities, vector velocity sequences were constructed and stroke volume calculated. Angle of insonation...... 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.......4 ml and 1.9 ml. The results indicate that reliable vector velocity estimates can be obtained in vivo using the presented angle-independent 2-D vector velocity method. The TO method can be a useful alternative to conventional Doppler systems by avoiding the angle artifact, thus giving quantitative...
Pacheco Rivera, Carlos Hernando
2012-01-01
A partir de la aplicación de una encuesta diagnóstica de ambiente escolar, se formula una estrategia pedagógica integrada al proyecto transversal PRAE (proyecto ambiental educativo), consistente en una serie de unidades didácticas encaminadas a fomentar la ética del cuidado en los estudiantes con respecto al manejo del ruido. Las evaluaciones posteriores demuestran una mejora en actitudes y prácticas en torno al ambiente sonoro de la institución escolar y adicionalmente otras problemáticas so...
Prominent transverse flow of clusters in stopped Au(150AMeV)+Au reactions
International Nuclear Information System (INIS)
Stopped Au(150AMeV)+Au collisions have been measured with the FOPI-Detector at GSI by imposing an upper limit on the ratio of the global longitudinal momentum to the collected charge within an event. The ejectiles, in particular those with Z>3, have a rapidity close to mid-rapidity and exhibit angular distributions in the centre-of-mass strongly peaking around 90 thus suggesting an enhancement of the flow in the transverse direction. Fits to the data and comparisons with QMD calculations indicate an averaged collective velocity in the transverse direction equal to 0.12c. Significance of the determined velocity and temperature values is discussed. ((orig.))
Detonation propagation in hydrogen-air mixtures with transverse concentration gradients
Boeck, L. R.; Berger, F. M.; Hasslberger, J.; Sattelmayer, T.
2016-03-01
The influence of transverse concentration gradients on detonation propagation in H_2-air mixtures is investigated experimentally in a wide parameter range. Detonation fronts are characterized by means of high-speed shadowgraphy, OH* imaging, pressure measurements, and soot foils. Steep concentration gradients at low average H_2 concentrations lead to single-headed detonations. A maximum velocity deficit compared to the Chapman-Jouguet velocity of 9 % is observed. Significant amounts of mixture seem to be consumed by turbulent deflagration behind the leading detonation. Wall pressure measurements show high local pressure peaks due to strong transverse waves caused by the concentration gradients. Higher average H_2 concentrations or weaker gradients allow for multi-headed detonation propagation.
The Potential for Ambient Plasma Wave Propulsion
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
Shear wave velocity structure in West Java, Indonesia as inferred from surface wave dispersion
Anggono, Titi; Syuhada
2016-02-01
We investigated the crust and upper mantle of West Java, Indonesia by measuring the group velocity dispersion of surface waves. We analyzed waveform from four teleseismic earthquake recorded at three 3-component broadband seismometers. We analyzed fundamental mode of Rayleigh and Love waves from vertical, radial, and transverse components using multiple filter technique. We inverted the measured group velocity to obtain shear wave velocity profile down to 200 km depth. We observed low shear wave velocity zone at depth of about 20 km. Shear velocity reduction is estimated to be 18% compared to the upper and lower velocity layer. The low velocity zone might be associated with the subducting slab of Indo-Australian Plate as similar characteristics of low velocity zones also observed at other subducting regions.
Fluidic angular velocity sensor
Berdahl, C. M. (Inventor)
1986-01-01
A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.
Quantitative velocity modulation spectroscopy
Hodges, James N.; McCall, Benjamin J.
2016-05-01
Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined.
Transverse and longitudinal angular momenta of light
International Nuclear Information System (INIS)
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
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.
Liebe, Wolfgang
1944-01-01
In many studies, especially of nonstationary flight motion, it is necessary to determine the angular velocities at which the airplane rotates about its various axes. The three-component recorder is designed to serve this purpose. If the angular velocity for one flight attitude is known, other important quantities can be derived from its time rate of change, such as the angular acceleration by differentiations, or - by integration - the angles of position of the airplane - that is, the angles formed by the airplane axes with the axis direction presented at the instant of the beginning of the motion that is to be investigated.
Essén, H
2003-01-01
This paper addresses the problem of the separation of rotational and internal motion. It introduces the concept of average angular velocity as the moment of inertia weighted average of particle angular velocities. It extends and elucidates the concept of Jellinek and Li (1989) of separation of the energy of overall rotation in an arbitrary (non-linear) $N$-particle system. It generalizes the so called Koenig's theorem on the two parts of the kinetic energy (center of mass plus internal) to three parts: center of mass, rotational, plus the remaining internal energy relative to an optimally translating and rotating frame.
Schimd, C.; Courtois, H.; Koda, J.
2015-12-01
A huge velocity survey based on the Maunakea Spectroscopic Explorer facility (MSE) is proposed, aiming at investigating the structure and dynamics of the cosmic web over 3π steradians up to ˜1 Gpc and at unprecedented spatial resolution, its relationship with the galaxy formation process, and the bias between galaxies and dark matter during the last three billions years. The cross-correlation of velocity and density fields will further allow the probe any deviation from General Relativity by measuring the the linear-growth rate of cosmic structures at precision competitive with high-redshift spectroscopic redshift surveys.
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 satisfacto...... 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....
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.
and analysis of P-wave attenuation anisotropy in transversely isotropic media Yaping Zhu1, Ilya Tsvankin2, Pawan Dewangan3, and Kasper van Wijk4 ABSTRACT Anisotropic attenuation can provide sensitive attributes for fracture detection and lithology...-preserving migration, and seismic fracture detec- tion. INTRODUCTION Most existing publications on seismic anisotropy are devoted to the influence of angular velocity variation in purely elastic media on the traveltimes and amplitudes of seismic waves. It is likely...
The transverse and rotational motions of magnetohydrodynamic kink waves in the solar atmosphere
International Nuclear Information System (INIS)
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.
Deformation and perforation of clamped work-hardening plates struck transversely by blunt missiles
International Nuclear Information System (INIS)
A simple theory is given in this paper for the behaviour of clamped circular work-hardening plates struck transversely by flat-ended projectiles which travel at low velocities. By closely following the previous studies, force-displacement relationships are obtained and used to predict the deformation and perforation of the plates. It is shown that the theoretical predictions agree well with the experimental results on fully clamped steel plates when strain rate effects are taken into account. (orig.)
On the possibility of Landau damping of the transverse plasma mode
International Nuclear Information System (INIS)
According to the standard theory the mechanism of Landau damping does not work in the case of the transverse electromagnetic mode of homogeneous nonmagnetized infinite plasma because the phase velocity of this mode is above the velocity of light. It is shown that this result of the standard theory is based on the assumption that the electrons and ions of the plasma are point charges. Taking into consideration the finite size, internal structure and polarizability of the ion cores, the dispersion relation must be modified and thus the Landau damping works. (D.Gy.)
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...
International Nuclear Information System (INIS)
Streamwise evolution of longitudinal and transverse velocity structure functions in a decaying homogeneous and nearly isotropic turbulence is reported for Reynolds numbers Reλ up to 720. First, two theoretical relations between longitudinal and transverse structure functions are examined in the light of recently derived relations and the results show that the low-order transverse structure functions can be well approximated by longitudinal ones within the sub-inertial range. Reconstruction of fourth-order transverse structure functions with a recently proposed relation by Grauer et al. is comparatively less valid than the relation already proposed by Antonia et al. Secondly, extended self-similarity methods are used to measure the scaling exponents up to order eight and the streamwise evolution of scaling exponents is explored. The scaling exponents of longitudinal structure functions are, at first location, close to Zybin's model, and at the fourth location, close to She—Leveque model. No obvious trend is found for the streamwise evolution of longitudinal scaling exponents, whereas, on the contrary, transverse scaling exponents become slightly smaller with the development of a steamwise direction. Finally, the stremwise variation of the order-dependent isotropy ratio indicates the turbulence at the last location is closer to isotropic than the other three locations. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Transverse fields in dielectric wake field accelerators
International Nuclear Information System (INIS)
Theory is presented for excitation of hybrid electric/magnetic (HEM) wake-field modes by passage of an electron drive bunch in a dielectric-lined cylindrical waveguide. The drive bunch is moving parallel to the waveguide axis, but is displaced by a radial increment r0. Knowledge of the amplitudes of all HEM modes allows calculation of the transverse forces on a bunch or bunches that follow the displaced drive bunch. Approximate formulas for the transverse forces on a trailing bunch are given, valid in the limit of small r0. These transverse forces can lead to beam instability, if cumulative transverse motion is significant on the time-scale of passage of the bunch through the accelerator module. Constructive interference can be present amongst TM0m monopole modes that produce highly-peaked spatiotemporally-localized axial wake-fields, with peak fields at the locations of trailing bunches in a multi-bunch train. In this case, the spectrum of dipole (and higher order) HEM modes may not enjoy the same degree of constructive interference, and may not have the same axial periodicity as the monopole modes. Further analytical and computational study is needed to determine the limitations that transverse wake fields may impose on a multi-bunch dielectric wake-field accelerator
Transverse fields in dielectric wake field accelerators
International Nuclear Information System (INIS)
Theory is presented for excitation of hybrid electric/magnetic (HEM) wake-field modes by passage of an electron drive bunch in a dielectric-lined cylindrical waveguide. The drive bunch is moving parallel to the waveguide axis, but is displaced by a radial increment r0. Knowledge of the amplitudes of all HEM modes allows calculation of the transverse forces on a bunch or bunches that follow the displaced drive bunch. Approximate formulas for the transverse forces on a trailing bunch are given, valid in the limit of small r0. These transverse forces can lead to beam instability, if cumulative transverse motion is significant on the time-scale of passage of the bunch through the accelerator module. Constructive interference can be present amongst TM0m monopole modes that produce highly-peaked spatiotemporally-localized axial wake-fields, with peak fields at the locations of trailing bunches in a multi-bunch train. In this case, the spectrum of dipole (and higher order) HEM modes may not enjoy the same degree of constructive interference, and may not have the same axial periodicity as the monopole modes. Further analytical and computational study is needed to determine the limitations that transverse wake fields may impose on a multi-bunch dielectric wake-field accelerator. copyright 1999 American Institute of Physics
Strange hadron production at low transverse momenta
Veres, Gábor I.; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Noell, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sawicki, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Teng, R.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wyslouch, B.; Zhang, J.
2004-01-01
Some of the latest results of the PHOBOS experiment from the \\sqrt{s_{NN}}= 200\\ GeV Au+Au data are discussed. Those relevant to strangeness production are emphasized. These observations relate to the nature of the matter created when heavy ions collide at the highest achieved energy. The invariant yields of strange and non-strange charged hadrons at very low transverse momentum have been measured, and used to differentiate between different dynamical scenarios. In the intermediate transverse momentum range, the measured ratios of strange and anti-strange kaons approach one, while the antibaryon to baryon ratio is still significantly less, independent of collision centrality and transverse momentum. At high transverse momenta, we find that central and peripheral Au+Au collisions produce similar numbers of charged hadrons per participant nucleon pair, rather than per binary nucleon-nucleon collision. Finally, we describe the upgrades of PHOBOS completed for the 2003 d+Au and p+p run, which extend the transverse momentum range over which particle identification is possible and, at the same time, implement a trigger system selective for high-pT particles.
De Luca, R.
2009-01-01
It is shown that, by applying elementary concepts in electromagnetism and electrochemistry to a system consisting of salt water flowing in a thin rectangular pipe at an average velocity v[subscript A] under the influence of a transverse magnetic field B[subscript 0], an electromotive force generator can be conceived. In fact, the Lorentz force…
Transverse and lateral confinement effects on the oscillations of a free cylinder in a viscous flow
Gianorio, Luciano; Cachile, Mario; Hulin, Jean-Pierre; Auradou, Harold
2013-01-01
The different types of instabilities of free cylinders (diameter $D$, length $L$) have been studied in a viscous flow (velocity $U$) between parallel vertical walls of horizontal width $W$ at a distance $H$: the influence of the confinement parameters $D/H$ and $L/W$ has been investigated. As $D/H$ increases, there is a transition from stable flow to oscillations transverse to the walls and then to a fluttering motion with oscillations of the angle of the axis with respect to the horizontal. The two types of oscillations may be superimposed in the transition domain. The frequency $f$ of the transverse oscillations is independent of the lateral confinement $L/W$ in the range: 0.055 \\le L/W \\le 0.94$ for a given cylinder velocity $V_{cx}$ and increases only weakly with $V_{cx}$. These results are accounted for by assuming a 2D local flow over the cylinder with a characteristic velocity independent of $L/W$ for a given $V_{cx}$ value. The experimental values of $f$ are also independent of the transverse confinem...
Khilkevich, Andrei; Shemyakin, Alexander V
2012-01-01
In Fermilab's electron cooler, a 0.1A, 4.3MeV DC electron beam propagates through the 20 m cooling section, which is immersed in a weak longitudinal magnetic field. A proper adjustment of 200 dipole coils, installed in the cooling section for correction of the magnetic field imperfections, can create a helix-like trajectory with the wavelength of 1-10 m. The longitudinal cooling force is measured in the presence of such helixes at different wavelengths and amplitudes. The results are compared with a model calculating the cooling force as a sum of collisions with small impact parameters, where the helical nature of the coherent angle is ignored, and far collisions, where the effect of the coherent motion is neglected. A qualitative agreement is found.
Modelling the transverse distribution of velocity and suspended sediment in tidal estuaries
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 pat
Multidisc neutron velocity selector
International Nuclear Information System (INIS)
The prototype of a velocity selector for neutron monochromatization in the 4-20 A wavelength range is presented. The theoretical background of the multidisc rotor system is given together with a description of the mechanical construction and electronic driving system. The first tests and neutron measurements prove easy handling and excellent parameters. (author) 6 refs.; 7 figs.; 2 tabs
The effect of an ambient flow on the spreading of a viscous gravity current
Eames, I.; Gilbertson, M.A.; Landeryou, M.
2005-01-01
The influence of an external laminar flow on the spreading of a viscous gravity current moving over a horizontal floor is studied theoretically and experimentally. The viscous stress exerted by the ambient flow drives the viscous gravity current streamwise with a velocity proportional to the local height of the current. The one-way coupling between the ambient flow and the spread of the current is examined. Similarity and numerical solutions are developed to describe viscous gravity currents ...
Transverse dynamics of dispersive Alfven waves. I. Direct numerical evidence of filamentation
International Nuclear Information System (INIS)
The three-dimensional dynamics of a small-amplitude monochromatic Alfven wave propagating along an ambient magnetic field is simulated by direct numerical integration of the Hall-magnetohydrodynamics equations. As predicted by the two-dimensional nonlinear Schroedinger equation or by more general amplitude equations retaining the coupling to low-frequency magnetosonic waves, the transverse instability of the pump leads to wave collapse and formation of intense magnetic filaments, in spite of the presence of competing, possibly linearly dominant, instabilities that in some instances distort the above structures. In computational boxes, including a large number of pump wavelengths, an early arrest of the collapse is possible under the effect of quasi-transverse instabilities that drive magnetosonic waves and also prescribe the directions of the filaments
Balandin, V; Golubeva, N
2014-01-01
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 gu...
Spin versus helicity in processes involving transversity
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.
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...
Distribution of Transverse Distances in Directed Animals
Sumedha; Dhar, Deepak
2003-01-01
We relate $\\phi(\\bf{x},s)$, the average number of sites at a transverse distance $\\bf{x}$ in the directed animals with $s$ sites in $d$ transverse dimensions, to the two-point correlation function of a lattice gas with nearest neighbor exclusion in $d$ dimensions. For large $s$, $\\phi(\\bf{x},s)$ has the scaling form $\\frac{s}{R_s^d} f(|\\bf{x}|/R_s)$, where $R_s$ is the root mean square radius of gyration of animals of $s$ sites. We determine the exact scaling function for $d =1$ to be $f(r) =...
Parton Energy Loss Without Transverse Momentum Broadening
Zapp, Korinna; Rathsman, Johan; Stachel, Johanna; Wiedemann, Urs Achim
2011-01-01
The JEWEL 1.0 Monte Carlo simulates jet evolution in a medium with a microscopic description of splitting and scattering processes. In the framework of this model we investigate the transverse momentum broadening due to medium effects in different scenarios. Depending on assumptions about hadronisation, we observe either a small increase or even a slight decrease of the mean transverse momentum, but no sizeable broadening. This appears to be a natural consequence of a model formulation which conserves energy and momentum microscopically at each splitting and at each scattering.
Isolated Transverse Sacrum Fracture: A Case Report
Directory of Open Access Journals (Sweden)
Cemil Kavalci
2011-01-01
Full Text Available Sacral fracture commonly results from high-energy trauma. Most insufficiency fractures of the sacrum are seen in women after the age of 70. Fractures of the sacrum are rare and generally combined with a concomitant pelvic fracture. Transverse sacral fractures are even less frequent which constitute only 3–5% of all sacral fractures. This type of fractures provide a diagnostic challenge. We report a unique case of isolated transverse fracture of sacrum in a young man sustained low-energy trauma. The patient presented to our emergency department after several hours of injury, and diagnosed by clinical features and roentgenogram findings.
Ambient Noise in an Urbanized Tidal Channel
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
A method to resolve low velocities in a PIV system
Bharadwaj, Sunil; Alam, Meheboob
2015-11-01
A method is proposed to improve the velocity-dynamic range (VDR) of particle-image velocimetry (PIV) technique. This method uses two different timings of a pulsed laser and an outlier detection technique that helped to measure very low velocities, bypassing the limits set by the VDR of the PIV-system. The lower limit of the resolvable velocity is not set by the algorithm but by the laser-timings. The reliability of the method is verified by carrying our planar measurements of the mean and fluctuation velocities in an axisymmetric jet at a Reynolds number of about 3500. The radial velocity, which is usually an order-of-magnitude lower than the axial velocity, is successfully resolved in the ambient region of the jet as compared to results obtained by employing the post-processing techniques of the standard PIV-system. Overall, the proposed method seems to increase the velocity-dynamic range of PIV-algorithm to capture low-velocities in an otherwise fast flow. Thsi work is supported by the BARC, Government of India (BARC/MA/4350).
Wave propagation and group velocity
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
Ambiente juvenil: discurso ambiental entre jóvenes universitarios
Quinn-Anderson, William C.
2008-01-01
Esta tesis pretende hacer una aportación al conocimiento del medio ambiente del occidente de México, específicamente de la zona metropolitana de Guadalajara, a partir del estudio de la cultura ambiental manifestada en el discurso de los jóvenes universitarios del ITESO. La apuesta es que puede ser provechoso considerar dentro del concepto de “medio ambiente” no solamente componentes bióticos y abióticos, sino también elementos socioculturales como cultura y significado. Es evidente que hay in...
Multidisk neutron velocity selectors
International Nuclear Information System (INIS)
Helical multidisk velocity selectors used for neutron scattering applications have been analyzed and tested experimentally. Design and performance considerations are discussed along with simple explanation of the basic concept. A simple progression is used for the inter-disk spacing in the 'Rosta' design. Ray tracing computer investigations are presented in order to assess the 'coverage' (how many absorbing layers are stacked along the path of 'wrong' wavelength neutrons) and the relative number of neutrons absorbed in each disk (and therefore the relative amount of gamma radiation emitted from each disk). We discuss whether a multidisk velocity selector can be operated in the 'reverse' configuration (i.e. the selector is turned by 1800 around a vertical axis with the rotor spun in the reverse direction). Experimental tests and calibration of a multidisk selector are reported together with evidence that a multidisk selector can be operated in the 'reverse' configuration. (orig.)
Kriging Interpolating Cosmic Velocity Field
Yu, Yu; Zhang, Jun; Jing, Yipeng; Zhang, Pengjie
2015-01-01
[abridged] Volume-weighted statistics of large scale peculiar velocity is preferred by peculiar velocity cosmology, since it is free of uncertainties of galaxy density bias entangled in mass-weighted statistics. However, measuring the volume-weighted velocity statistics from galaxy (halo/simulation particle) velocity data is challenging. For the first time, we apply the Kriging interpolation to obtain the volume-weighted velocity field. Kriging is a minimum variance estimator. It predicts the...
Slip-velocity and drag of large neutrally-buoyant particles in turbulent flows
Bellani, Gabriele
2012-01-01
We discuss possible definitions for a 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. By decomposing drag into steady and stochastic components, we obtain both a steady slip velocity and a fluctuating slip velocity. From this decomposition, we propose two definitions for stochastic slip velocity. These definitions were 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...
Italian and Alpine crustal structure imaged by ambient-noise surface-wave dispersion
Molinari, I.; Boschi, L.; Verbeke, J.; Morelli, A.; Kissling, E. H.
2014-12-01
Surface-wave dispersion measurements based on seismic background signal (ambient noise) are a very effective means to image S-wave velocity at crustal and lithospheric depths. The goal of our study is to integrate new ambient noise data for central Europe with more traditional models of crustal heterogeneity and discontinuity depths. We find that the reference crustal model EPcrust (Molinari and Morelli, 2011) is in good agreement with the large database of one-year-long records of European ambient noise compiled by Verbeke et al. (2012). We use the same data to further improve EPcrust, obtaining a new three-dimensional model of Italian and Alpine crustal structure. We first conduct a linear least squares inversion of the available phase-velocity observations, resulting in a set of Rayleigh-wave phase-velocity maps at periods between 5 and 37 s. At relatively short periods, these maps clearly reflect the surface geology of the region, e.g. low velocity zones at the Po Plain; longer-period maps reveal deeper structures such as Moho topography under Alps and Appennines, and lower crustal anomalies. The phase-velocity maps are next inverted via the Neighbourhood Algorithm to determine a set of one-dimensional shear-velocity models (one per phase-velocity pixel), which are in turn interpolated to build a new three-dimensional model and Moho depth. The reconstructed model shows the low velocity area beneath the Po Plain; the contrast between the low-velocity crust of the Adriatic domain and the high-velocity crust of the Tyrrhenian domain is clearly seen, as well as an almost uniform crystalline crust beneath the Alpine belt. Our results are physically consistent with the information for velocity structure and Moho depth independently obtained by other seismic methods.
Sex Education as a Transversal Subject
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…
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....
Simulations of a Detonation Wave in Transverse Magnetic Fields
Cole, Lord; Karagozian, Ann; Cambier, Jean-Luc
2010-11-01
Numerical simulations of magneto-hydrodynamic (MHD) effects on detonation wave structures are performed, with applications to flow control and MHD power extraction in Pulse Detonation Engines (PDE) and their design variations. In contrast to prior studies of MHD interactions in PDEs,ootnotetextCambier, et al., AIAA-2008-4688 the effects of the finite relaxation length scale for ionization on the stability of the detonation wave are examined. Depending on the coupling parameters, the magnetic field can quench the detonation and effectively act as a barrier to its propagation. Conversely, an applied transient magnetic field can exert a force on a pre-ionized gas and accelerate it. The dynamics are subject to non-linear effects; a propagating transverse magnetic field will initially exert a small force if the gas has a low conductivity and the magnetic Reynolds number (Rem) is low. Nevertheless, the gas accelerated by the "piston" action of the field can pre-heat the ambient gas and increase its conductivity. As the wave progresses, Rem increases and the magnetic field becomes increasingly effective. The dynamics of this process are examined in detail with a high-order shock-capturing method and full kinetics of combustion and ionization. The complex chemical kinetics calculations are ported onto a GPU using the CUDA language, and computational performance is compared with standard CPU-based computations.
Ambient Seismic Noise Tomography of a Loess High Bank at Dunaszekcső (Hungary)
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.
Ambient Seismic Noise Tomography of a High Loess Bank at Dunaszekcső (Hungary)
Szanyi, Gyöngyvér; Gráczer, Zoltán; Győri, Erzsébet; Kaláb, Zdeněk; Lednická, Markéta
2016-05-01
High loess 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 high loess 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.
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.
Collision Kernels from Velocity-Selective Optical Pumping with Magnetic Depolarization
Bhamre, T; Kominis, I K; McGuyer, B H; Happer, W
2013-01-01
We experimentally demonstrate how magnetic depolarization of velocity-selective optical pumping can be used to single out the collisional cusp kernel best describing spin and velocity relaxing collisions between potassium atoms and low pressure helium. The range of pressures and transverse fields used simulate the novel optical pumping regime pertinent to sodium guidestars employed in adaptive optics. We measure the precession of spin-velocity modes under the application of transverse magnetic fields, simulating the natural configuration of mesospheric sodium optical pumping in the geomagnetic field. We also provide a full theoretical account of the experimental data using the recently developed cusp kernels, which realistically quantify velocity damping collisions in this novel optical pumping regime. A single cusp kernel with a sharpness $s=13\\pm 2$ provides a global fit to the K-He data.
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...... firewalls that are not guaranteed to be protective. This is based on a control flow analysis for recording what processes may turn up inside what other processes; in particular, we develop a syntax-directed system for specifying the acceptability of an analysis, we prove that all acceptable analyses are...... semantically sound, and we demonstrate that each process admits a least analysis....
Ambient cosmology and spacetime singularities
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.
Ambient cosmology and spacetime singularities
International Nuclear Information System (INIS)
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.)
Medio ambiente y responsabilidad social
Roa Buitrago, Rosa Isabel
2012-01-01
Las organizaciones, dentro de los procesos de responsabilidad social y con el fin de mejorar la calidad de vida de las comunidades que impactan, han optado por proteger y preservar el medio ambiente de acuerdo a ciertos protocolos y normas internacionales que generan una cultura al respecto. Este cuaderno de investigación aborda la norma ISO 26000, la cual asume el tema de la Responsabilidad Social Empresarial (RSE) en materia de medio ambiente y es una guía para ser implementada en las orga...
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.)
Los estudios sobre el ambiente y la ciencia ambiental
Directory of Open Access Journals (Sweden)
Amelia Nancy Giannuzzo
2010-03-01
Full Text Available La existencia de la ciencia ambiental es reconocida en libros, revistas de publicación científica y carreras de grado y posgrado. Sin embargo, se desconoce su existencia en forma literal o indirecta, al no ser considerado su aporte, por ejemplo, en los planteos referidos sobre la ciencia y la tecnología de la sustentabilidad. En este trabajo se presentan estos antecedentes, relacionándolos con el objetivo del mismo, que es el de aportar a la dilucidación de la existencia y conformación de la ciencia ambiental. Para esto, se analiza la relación de las disciplinas con la dimensión compleja del ambiente como objeto de estudio y aspectos metodológicos derivados. A los fines de aportar al esclarecimiento conceptual, se identifican las distintas acepciones de ambiente comúnmente referidas en la bibliografía. Además, se discuten aspectos relacionados de multidisciplinariedad, interdisciplinariedad y transdisciplinariedad, y sobre el status epistémico de la ciencia ambiental. Se concluye que una mayor precisión conceptual embasada en un marco compartido por las disciplinas que estudian el ambiente, incluida la ciencia ambiental, y los distintos actores involucrados en las problemáticas ambientales, favorecerá el refinamiento de las metodologías tendientes a disminuir la fragmentación de las investigaciones concernientes y las aplicaciones para su resolución.The existence of an environmental science is recognized in books, journals of science as well as in undergraduate and graduate studies. Its existence, however, is unknown either literally or indirectly when, for instance, its contribution to topics connected to the science and technology of sustainability is not considered. This background is presented in this paper and connected to its objective, which is to elucidate the existence and structure of the environmental science. To this goal, I analyse the relationship of the disciplines with the complex dimension of the environment
Variation of Quench Propagation Velocities in YBCO Cables
Härö, E.; Stenvall, A.; 10.1007/s10948-015-2976-y
2015-01-01
changes during the quench. Due to the large temperature margin between the operation and the current sharing temperatures, the normal zone does not propagate with the temperature front. This means that the temperature will rise in a considerably larger volume when compared to the quenched volume. Thus, the evolution of the temperature distribution below current sharing temperature Tcs after the quench onset affects the normal zone propagation velocity in HTS more than in LTS coils. This can be seen as an acceleration of the quench propagation velocities while the quench evolves when margin to Tcs is high. In this paper we scrutinize quench propagation in a stack of YBCO cables with an in-house finite element method software which solves the heat diffusion equation. We compute the longitudinal and transverse normal zone propagation velocities at various distances from the hot spot to demonstrate the distance-variation...
Mapping of moveout in tilted transversely isotropic media
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.
Effectiveness of street sweeping and washing for controlling ambient TSP
Chang, Yu-Min; Chou, Chih-Mei; Su, Kuo-Tung; Tseng, Chao-Heng
Effectiveness of street sweeping and washing (S/W) for controlling ambient "total suspended particles (TSP)" was evaluated by TSP measurements and determining silt load from active traffic streets. A modified regenerative-air vacuum sweeper (RAVS) and a washer were used in this study. The sweeper made a pass followed by the washer. The S/W efficiencies (η,η) were obtained based on the experimental data of silt loading and TSP. It was found that the direct impact of sweeping on ambient TSP emissions was short-lived lasting no more than 3-4 h. When a vacuum sweeper and a washer, respectively, did a good job collecting or cleaning the visible fine particles on roads, the method of S/W tested in this work was effective at removing the sources of the road dust particles. This paper concludes that street sweeping followed by washing was found to offer a measurable reduction in TSP emission potentials. Typically, the reduction efficiency of ambient TSP is up to 30%. Finally, correlated with η (based on silt loading), a useful equation is proposed to estimate the S/W efficiency, η (based on TSP) with a standard error of ±20%. It seems feasible to predict the reduction efficiency of ambient TSP controlled by the regenerative-air vacuum sweeper and washer used in this work for engineering applications. Effects of traffic volume and wind velocity on the S/W efficiencies are also discussed in the paper.
Kopp, Robert William
1989-01-01
Hypervelocity flows for velocities is excess of 1.4 km/sec (Mach 5) require very high stagnation temperature to avoid liquefaction. The arc heater wind tunnel has been designed to provide such flows. The electric-are driven wind tunnel can develop stagnation temperatures up to 13,000 K which will produce hypervelocity flows up to 7 km/sec (earth orbital speed). The nature of the flow, however, is such that the high temperature source flow may cause severe gradients at the nozzle exit. In orde...
Dark Matter Velocity Spectroscopy.
Speckhard, Eric G; Ng, Kenny C Y; Beacom, John F; Laha, Ranjan
2016-01-22
Dark matter decays or annihilations that produce linelike spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming experiments will have the precision needed. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications. PMID:26849582
Dark Matter Velocity Spectroscopy
Speckhard, Eric G; Beacom, John F; Laha, Ranjan
2016-01-01
Dark matter decays or annihilations that produce line-like spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming and proposed experiments will make significant improvements. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.
Ambient seismic noise tomography of Jeju Island, South Korea
Lee, S. J.; Rhie, J.; Kim, S.; Kang, T. S.; Kim, Y.
2015-12-01
Jeju Island, formed by Cenozoic basaltic eruptions, is an island off the southern coast of the Korean Peninsula. This volcanic island is far from the plate boundaries and the fundamental cause of the volcanic activity in this region is not understood well. To understand the origin of the island, resolving the detailed seismic velocity structures is crucial. Therefore, we applied ambient noise tomography to study the velocity structures of the island. Continuous waveform data recorded at 20 temporary and 3 permanent broad-band seismic stations are used. The group and phase velocity dispersion curves of the fundamental mode Rayleigh waves are extracted from cross-correlograms for 253 station pairs by adopting multiple filter technique. The fast marching method and the subspace method are jointly applied to construct 2-D group and phase velocity maps for periods ranging between 1 and 15 s. 1-D shear wave velocity models and their uncertainties are estimated by the Bayesian technique. The optimal number of the layers are determined at the end of the burn-in period based on the Bayesian Information Criteria (BIC). Final 3-D velocity model of the island is constructed by compiling 1-D models. In our 3-D model, a distinct low velocity anomaly appears beneath Mt. Halla from surface to about 6 km depth. The surficial extent of the anomaly is more or less consistent with the surface geologic feature of the third-stage basaltic eruption reported by previous studies but the vertical extension of the anomaly is not well constrained. To improve the velocity model, especially enhance the vertical resolution of the anomaly, we will apply joint analysis of the surface wave dispersions and teleseismic receiver functions. The improved model will provide more information to infer the tectonic or volcanic implications of the anomaly and unravel the origin of the strange volcanic island in South Korea.
Transverse instability of transverse-magnetic solitons and nonlinear surface plasmons.
Lin, Yuan-Yao; Lee, Ray-Kuang; Kivshar, Yuri S
2009-10-01
We analyze stability of the TM polarized optical solitons and nonlinear guided waves localized at a metal-dielectric interface. We demonstrate, both analytically and numerically, that the spatial solitons can experience vectorial transverse modulational instability that leads to the generation of arrays of two-dimensional TM polarized self-trapped localized beams. In a sharp contrast, we reveal that the transverse instability is completely eliminated for nonlinear surface plasmons. PMID:19794789
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.
Shape analysis for Mobile Ambients
DEFF Research Database (Denmark)
Nielson, Hanne Riis; Nielson, Flemming
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. The...
Abstract Interpretation of Mobile Ambients
DEFF Research Database (Denmark)
Hansen, René Rydhof; Jensen, J. G.; Nielson, Flemming; Nielson, Hanne Riis
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 for...
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...
TERCEIRO SETOR E MEIO AMBIENTE
Melo, Marina Félix de
2012-01-01
Objetivamos discutir, brevemente, como têm se dado as discussões sobre o Terceiro Setor brasileiro e, particularmente, sobre as ONGs que atuam em defesa do meio ambiente, levantando questionamentos acerca das limitações enfrentadas pelo Terceiro Setor neste contexto
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. The ...
Dong, Zhichao; Cheng, Haobo; Tam, Hon-Yuen
2015-02-10
The velocity-varying regime used in deterministic subaperture polishing employs a time-invariant tool influence function (TIF) to figure localized surface errors by varying the transverse velocities of polishing tools. Desired transverse velocities have to be truncated if they exceed the maximal velocity of computer numerical control (CNC) machines, which induces excessive material removal and reduces figuring efficiency (FE). A time-variant (TV) TIF regime is presented, in which a TIF serves as a variable to compensate for excessive material removal when the transverse velocities are truncated. Compared with other methods, the TV-TIF regime exhibits better performance in terms of convergence rate, FE, and versatility; its operability can also be strengthened by a TIF library. Comparative experiments were conducted on a magnetorheological finishing machine to validate the effectiveness of the TV-TIF regime. Without a TV-TIF, the tool made an unwished dent (depth of 76 nm) at the center because of the velocity truncation problem. Through compensation with a TV-TIF, the dent was completely removed by the second figuring process, and a TV-TIF improved the FE from 0.029 to 0.066 mm(3)/h. PMID:25968037
Turbulent Boyant Jets and Plumes in Flowing Ambient Environments
DEFF Research Database (Denmark)
Chen, Hai-Bo
Turbulent buoyant jets and plumes in flowing ambient environments have been studied theoretically and experimentally. The mechanics of turbulent buoyant jets and plumes in flowing ambients have been discussed. Dimensional analysis was employed to investigate the mean behaviour of the turbulent...... buoyant jets and plumes, such as the jet trajectories and the dilutions. The basic physical processes for a submerged turbulent buoyant jet released from sea outfall have been outlined and divided into four primary stages, namely, the zone of flow establishment, the stage of jet, the stage of intermediate...... and the stage of plume. The stability criteria for the upstream wedge created by the submerged turbulent buoyant jet were established by applying the Bernoulli equations for a two-dimensional problem and by considering the front velocity driven by the buoyancy force for a three-dimensional problem...
International Nuclear Information System (INIS)
This paper deals with the quasi-dc electric fields measured in the CRIT I ionospheric release experiment, which was launched from Wallops Island on May 13, 1986. The purpose of the experiment was to study the critical ionization velocity (CIV) mechanism in the ionosphere. Two identical barium shaped charges were fired from distances of 1.99 km and 4.34 km towards a main payload, which made full three-dimensional measurements of the electric field inside the streams. There was also a subpayload separated from the main payload by a couple of kilometers along the magnetic field. The relevance of earlier proposed mechanisms for electron heating in CIV is investigated in the light of the CRIT I results. It is concluded that both the homogeneous and the ionizing front models probably apply, but in different parts of the stream. It is also possible that electrons are directly accelerated by a magnetic-field-aligned component of the electric field; the quasi-dc electric field observed within the streams had a large magnetic-field-aligned component, persisting on the time scale of the passage of the streams. The coupling between the ambient ionosphere and the ionized barium stream in CRIT I was more complicated than is usually assumed in CIV theories, with strong magnetic-field-aligned electric fields and probably current limitation as important processes. One interpretation of the quasi-dc electric field data is that the internal electric fields of the streams were not greatly modified by magnetic-field-aligned currents, i.e., a state was established where the transverse currents were to a first approximation divergence-free. It is argued that this interpretation can explain both a reversal of the strong explosion-directed electric field in burst 1 and the absence of such a reversal in burst 2
Directory of Open Access Journals (Sweden)
Sorin Nedelcu
2014-12-01
Full Text Available By molecular dynamics simulations we investigate the transport of charged polymers in confinement, under externally applied electric fields, in straight cylinders of uniform diameter and in the presence of monovalent or multivalent counterions. The applied electric field has two components; a longitudinal component along the axis of the cylinder and a transversal component perpendicular to the cylinder axis. The direction of electrophoretic velocity depends on the polyelectrolyte length, valency of the counterions present in solution and transversal electric field value. A statistical model is put forward in order to explain these observations.
The effect of laser beam size in a zig-zag collimator on transverse cooling of a krypton atomic beam
Indian Academy of Sciences (India)
Vivek Singh; V B Tiwari; S Singh; S R Mishra; H S Rawat
2014-07-01
The effect of size of a cooling laser beam in a zig-zag atomic beam collimator on transverse cooling of a krypton atomic beam is investigated. The simulation results show that discreteness in the interaction between the cooling laser beam and atomic beam, arising due to finite size and incidence angle of the cooling laser beam, significantly reduces the value of transverse velocity capture range of the collimator. The experimental observations show the trend similar to that obtained from simulations. Our study can be particularly useful where a small zig-zag collimator is required.
Vertical Dynamic Response of Pile Embedded in Layered Transversely Isotropic Soil
Directory of Open Access Journals (Sweden)
Wenbing Wu
2014-01-01
Full Text Available The dynamic response of pile embedded in layered transversely isotropic soil and subjected to arbitrary vertical harmonic force is investigated. Based on the viscoelastic constitutive relations for a transversely isotropic medium, the dynamic governing equation of the transversely isotropic soil is obtained in cylindrical coordinates. By introducing the fictitious soil pile model and the distributed Voigt model, the governing equations of soil-pile system are also derived. Firstly, the vertical response of the soil layer is solved by using the Laplace transform technique and the separation of variables technique. Secondly, the analytical solution of velocity response in the frequency domain and its corresponding semianalytical solution of velocity response in the time domain are derived by means of inverse Fourier transform and convolution theorem. Finally, based on the obtained solutions, a parametric study has been conducted to investigate the influence of the soil anisotropy on the vertical dynamic response of pile. It can be seen that the influence of the shear modulus of soil in the vertical plane on the dynamic response of pile is more notable than the influence of the shear modulus of soil in the horizontal plane on the dynamic response of pile.
Wang, Yongjia; Li, Qingfeng; Zhang, Hongfei; Leifels, Y; Trautmann, W
2014-01-01
Within the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model, the transverse-velocity dependence of the elliptic flow of free nucleons from $^{197}$Au+$^{197}$Au collisions at the incident energy 400 MeV$/$nucleon is studied within different windows of the normalized c.m. rapidity $y_0$. It is found that the elliptic flow difference $v_{2}^{n}$-$v_{2}^{p}$ and ratio $v_{2}^{n}$/$v_{2}^{p}$ of neutrons versus protons are sensitive to the density dependence of the symmetry energy, especially the ratio $v_{2}^{n}$/$v_{2}^{p}$ at small transverse velocity in the intermediate rapidity intervals $0.4<|y_0|<0.6$. By comparing either transverse-momentum dependent or integrated FOPI/LAND elliptic flow data of nucleons and hydrogen isotopes with calculations using various Skyrme interactions, all exhibiting similar values of isoscalar incompressibility but very different density dependences of the symmetry energy, a moderately soft to linear symmetry energy is extracted, in g...
Transverse jet-cavity interactions with the influence of an impinging shock
International Nuclear Information System (INIS)
Highlights: • Experimental study of shock-jet-cavity in a supersonic freestream is conducted. • Shock impingement at the cavity leading edge lifts the shear layer, encouraging momentum transfer. • Shock impingement close to the jet location increases the number of smaller turbulent structures. - Abstract: For high-speed air breathing engines, fuel injection and subsequent mixing with air is paramount for combustion. The high freestream velocity poses a great challenge to efficient mixing both in macroscale and microscale. Utilising cavities downstream of fuel injection locations, as a means to hold the flow and stabilise the combustion, is one mechanism which has attracted much attention, requiring further research to study the unsteady flow features and interactions occurring within the cavity. In this study we combine the transverse jet injection upstream of a cavity with an impinging shock to see how this interaction influences the cavity flow, since impinging shocks have been shown to enhance mixing of transverse jets. Utilising qualitative and quantitative methods: schlieren, oilflow, PIV, and PSP the induced flowfield is analysed. The impinging shock lifts the shear layer over the cavity and combined with the instabilities generated by the transverse jet creates a highly complicated flowfield with numerous vertical structures. The interaction between the oblique shock and the jet leads to a relatively uniform velocity distribution within the cavity
Polarization transport of transverse acoustic waves: Berry phase and spin Hall effect of phonons
Bliokh, K. Yu.; Freilikher, V. D.
2006-11-01
We carry out a detailed analysis of the short-wave (semiclassical) approximation for the linear equations of the elasticity in a smoothly inhomogeneous isotropic medium. It is shown that the polarization properties of the transverse waves are completely analogous to those of electromagnetic waves and can be considered as spin properties of optical phonons. In particular, the Hamiltonian of the transverse waves contains an additional term of the phonon spin-orbit interaction arising from the Berry gauge potential in the momentum space. This potential is diagonal in the basis of the circularly polarized waves and corresponds to the field of two “magnetic monopoles” of opposite signs for phonons of opposite helicities. This leads to the appearance of the Berry phase in the equation for the polarization evolution and an additional “anomalous velocity” term in the ray equations. The anomalous velocity has the form of the “Lorentz force” caused by the Berry gauge field in momentum space and gives rise to the transverse transport of waves of opposite helicities in opposite directions. This is a manifestation of the spin Hall effect of optical phonons. The effect directly relates to the conservation of total angular momentum of phonons and also influences reflection from a sharp boundary (acoustic analog of the transverse Ferdorov-Imbert shift).
Transverse mixing characteristics of the Missouri River downstream from the Cooper Nuclear Station
International Nuclear Information System (INIS)
The transverse mixing characteristics of the Missouri River in the vicinity of the Cooper Nuclear Station near Brownville, Nebraska, were investigated using the fluorescent-dye tracer technique. Rhodamine WT dye, introduced continuously into the plant once-through circulating-water system, was used to simulate the waste heat. Transverse profiles of dye concentration, depth, and velocity were obtained at several cross sections in the six-mile reach immediately downstream from the plant. The results indicate that the excess temperature in the river at full plant load can be reduced by dilution to less than 50F within a 45-acre mixing zone with the present discharge canal system, provided that the river discharge is not less than about 20,000 cfs. For lower river discharges, some additional mixing would be required to achieve the same reduction. Based on a more detailed analysis of the transverse mixing process, the dimensionless transverse mixing coefficient in the six-mile reach downstream from the plant was found to have average and maximum values that are believed to considerably exceed any previously published values
Recession velocities greater than light
International Nuclear Information System (INIS)
It is shown that, for the most commonly discussed models of general relativistic cosmology, distant objects whose velocity of recession exceeds the velocity of light can be observed. Since these are not kinematic velocities there is no violation of the light principle of relativity which can be taken to be:- (1) the velocity of light is a universal constant and (2) a beam of light cannot be overtaken by any material object nor by another light beam. (UK)
Partonic Picture of Generalized Transverse Momentum Distributions
Liuti, Simonetta; Goldstein, Gary R; Hernandez, J Osvaldo Gonzalez; Rajan, Abha
2013-01-01
We argue that due to parity constraints, the helicity combination of the purely momentum space counterparts of the Wigner distributions -- the generalized transverse momentum distributions -- that describes the configuration of an unpolarized quark in a longitudinally polarized nucleon, can enter the deeply virtual Compton scattering amplitude only through matrix elements involving a final state interaction. The relevant matrix elements in turn involve light cone operators projections in the transverse direction, or they appear in the deeply virtual Compton scattering amplitude at twist three. Orbital angular momentum or the spin structure of the nucleon was a major reason for these various distributions and amplitudes to have been introduced. We show that twist three contributions to deeply virtual Compton scattering provide observables related to orbital angular momentum.
Transverse acousto-electric effect in superconductors
Lipavský, P.; Koláček, J.; Lin, P.-J.
2016-06-01
We formulate a theory based on the time-dependent Ginzburg-Landau (TDGL) theory and Newtonian vortex dynamics to study the transverse acousto-electric response of a type-II superconductor with Abrikosov vortex lattice. When exposed to a transverse acoustic wave, Cooper pairs emerge from the moving atomic lattice and moving electrons. As in the Tolman-Stewart effect in a normal metal, an electromagnetic field is radiated from the superconductor. We adapt the equilibrium-based TDGL theory to this non-equilibrium system by using a floating condensation kernel. Due to the interaction between normal and superconducting components, the radiated electric field as a function of magnetic field attains a maximum value occurring below the upper critical magnetic field. This local increase in electric field has weak temperature dependence and is suppressed by the presence of impurities in the superconductor.
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.
Electron tube with transverse cyclotron interaction
Energy Technology Data Exchange (ETDEWEB)
Chodorow, M.
1985-04-23
An electron-beam tube for generating high microwave power at high frequencies comprises a fast-wave circuit such as a hollow waveguide. The circuit wave has a component of electric field perpendicular to its propagation axis. This field interacts with motions of the electrons transverse to the axis, in particular cyclotron rotation in an axial magnetic field. The above features are common to the well-known ''gyrotrons''. In the inventive tube the fast-wave circuit has means for locking a linearly polarized transverse-electric mode to the orientation of a circuit member such as the ridge in a ridged waveguide. The member (ridge) rotates spirally with distance along the guide. The added periodicity permits interaction with a space harmonic of the circuit wave. The -1 harmonic has a dispersion characteristic which provides beam-wave interaction over a wider frequency range than is possible in prior-art tubes of the gyrotron type.
Electron tube with transverse cyclotron interaction
International Nuclear Information System (INIS)
An electron-beam tube for generating high microwave power at high frequencies comprises a fast-wave circuit such as a hollow waveguide. The circuit wave has a component of electric field perpendicular to its propagation axis. This field interacts with motions of the electrons transverse to the axis, in particular cyclotron rotation in an axial magnetic field. The above features are common to the well-known ''gyrotrons''. In the inventive tube the fast-wave circuit has means for locking a linearly polarized transverse-electric mode to the orientation of a circuit member such as the ridge in a ridged waveguide. The member (ridge) rotates spirally with distance along the guide. The added periodicity permits interaction with a space harmonic of the circuit wave. The -1 harmonic has a dispersion characteristic which provides beam-wave interaction over a wider frequency range than is possible in prior-art tubes of the gyrotron type
Internal analysis of a transverse flux sensor
Energy Technology Data Exchange (ETDEWEB)
Voyant, J.-Yves [Laboratoire d' Electrotechnique de Grenoble-UMR 5529 INPG/UJF-CNRS-ENSIEG, BP 46, 38402 Saint-Martin-d' Heres Cedex (France)]. E-mail: jean-yves.voyant@leg.ensieg.inpg.fr; Yonnet, J.-Paul [Laboratoire d' Electrotechnique de Grenoble-UMR 5529 INPG/UJF-CNRS-ENSIEG, BP 46, 38402 Saint-Martin-d' Heres Cedex (France); Jay, Guillaume [Precilec, 41, 47 rue Guynemer, B.P. 239, 89002 AUXERRE Cedex (France); Foucher, Christian [Precilec, 41, 47 rue Guynemer, B.P. 239, 89002 AUXERRE Cedex (France)
2005-04-15
Rotary variable differential transformer (RVDT) sensors are used for industrial applications and are appreciated for their frictionless operation, reliability, linearity and sensitivity. The sensor shown here derives from a classic RVDT and is based on a differential rotating transformer. The functioning principle is explained and experimental measurements are shown. The originality of the studied sensor lies in the transverse flux design which gives a linearity error less than 0.1% of the stroke. However, this transverse flux circulation has uncommon features for an electrotechnical system due to flux paths which are not enclosed in radial planes. Finite element and experimental analysis are used for the magnetic study. This study aims to enhance sensor performances and manufacturing easiness.
The Tsallis distribution at large transverse momenta
Energy Technology Data Exchange (ETDEWEB)
Azmi, M.D. [Aligarh Muslim University, HEP Lab, Physics Department, Aligarh (India); Cleymans, J. [University of Cape Town, Physics Department, UCT-CERN Research Centre, Cape Town (South Africa)
2015-09-15
The charged particle transverse momentum (p{sub T}) spectra measured by the ATLAS and CMS collaborations for proton.proton collisions at √(s) = 0.9 and 7 TeV have been studied using Tsallis thermodynamics.Athermodynamically consistent form of the Tsallis distribution is used for fitting the transverse momentum spectra at mid-rapidity. It is found that the fits based on the proposed distribution are working over 14 orders of magnitude with p{sub T} values up to 200 GeV/c and this gives a value of χ{sup 2}/NDF of 0.52/24 for the CMS data at 7 TeV. The values for (dN)/(dy) vertical stroke {sub y=0} as a function of center-of-mass energy obtained using a Tsallis distribution for both ATLAS and CMS data sets are presented and discussed. (orig.)
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...
MEASUREMENT OF TRANSVERSE ECHOES IN RHIC.
Energy Technology Data Exchange (ETDEWEB)
FISCHER, W.; SATOGATA, T.; TOMAS. R.
2005-05-16
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 {tau} after the dipole kick, the beam re-cohered at time 2{tau} 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.
From transverse angular momentum to photonic wheels
Aiello, Andrea; Banzer, Peter; Neugebauer, Martin; Leuchs, Gerd
2015-12-01
Scientists have known for more than a century that light possesses both linear and angular momenta along the direction of propagation. However, only recent advances in optics have led to the notion of spinning electromagnetic fields capable of carrying angular momenta transverse to the direction of motion. Such fields enable numerous applications in nano-optics, biosensing and near-field microscopy, including three-dimensional control over atoms, molecules and nanostructures, and allowing for the realization of chiral nanophotonic interfaces and plasmonic devices. Here, we report on recent developments of optics with light carrying transverse spin. We present both the underlying principles and the latest achievements, and also highlight new capabilities and future applications emerging from this young yet already advanced field of research.
Distribution of transverse distances in directed animals
International Nuclear Information System (INIS)
We relate φ(x, s), the average number of sites at a transverse distance x in the directed animals with s sites in d transverse dimensions, to the two-point correlation function of a lattice gas with nearest neighbour exclusion in d dimensions. For large s, φ(x, s) has the scaling form s/Rds f(|x|/Rs), where Rs is the root-mean square radius of gyration of animals of s sites. We determine the exact scaling function for d = 1 to be f(r) = √π/2√3 erfc(r/√3). We also show that φ(x = 0, s) can be determined in terms of the animal number generating function of the directed animals
Distribution of transverse distances in directed animals
Sumedha; Dhar, Deepak
2003-04-01
We relate phi(x, s), the average number of sites at a transverse distance x in the directed animals with s sites in d transverse dimensions, to the two-point correlation function of a lattice gas with nearest neighbour exclusion in d dimensions. For large s, phi(x, s) has the scaling form s/Rds f(|x|/Rs), where Rs is the root-mean square radius of gyration of animals of s sites. We determine the exact scaling function for d = 1 to be f(r) = surdpi/2surd3 erfc(r/surd3). We also show that phi(x = 0, s) can be determined in terms of the animal number generating function of the directed animals.
Distribution of transverse distances in directed animals
Sumedha
2003-01-01
We relate phi(x, s), the average number of sites at a transverse distance x in the directed animals with s sites in d transverse dimensions, to the two-point correlation function of a lattice gas with nearest neighbour exclusion in d dimensions. For large s, phi(x, s) has the scaling form s/R sup d sub s f(|x|/R sub s), where R sub s is the root-mean square radius of gyration of animals of s sites. We determine the exact scaling function for d = 1 to be f(r) = sq root pi/2 sq root 3 erfc(r/sq root 3). We also show that phi(x = 0, s) can be determined in terms of the animal number generating function of the directed animals.
Idiopathic intracranial hypertension and transverse sinus stenoses
DEFF Research Database (Denmark)
Skyrman, Simon; Fytagoridis, Anders; Andresen, Morten; Bartek, Jiri Jr.
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...... associated with the IIH. Initial treatment consisted of symptom relief by a temporary lumbar drain for cerebrospinal fluid (CSF) diversion, while the pros and cons of a more permanent solution by insertion of a ventriculoperitoneal shunt (VPS) or bilateral transverse sinus stent was discussed. A VPS 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....
The transverse shape of the electron
Hoyer, Paul
2009-01-01
We study the charge density, form factors and spin distributions of the electron induced by its |e \\gamma> light-front Fock state in impact parameter space. Only transversally compact Fock states contribute to the leading behavior of the Dirac and Pauli form factors as the momentum transfer tends to infinity. Power suppressed contributions are not compact, and distributions weighted by the transverse size have end-point contributions. The Fock state conserves the spin of the parent electron locally, but the separate contributions of the electron, photon and orbital angular momentum depend on longitudinal momentum and impact parameter. The sign of the anomalous magnetic moment of the electron may be understood intuitively from the density distribution, addressing a challenge by Feynman.
Atomic interference patterns in the transverse plane
Boustimi, M.; Bocvarski, V.; de Lesegno, B. Viaris; Brodsky, K.; Perales, F.; Baudon, J.; Robert, J.
2000-03-01
A quadrupolar static magnetic field used as a phase object in a Stern-Gerlach atom interferometer produces phase shifts proportional to the distance to the zero-field line. As a consequence the transverse intensity profile of the atomic beam beyond the interferometer is modulated by an interference pattern which is a ``phase portrait'' of the field configuration. This pattern-a central bright spot surrounded by annular fringes-can be translated as a whole in any transverse direction by adding a homogeneous field to the quadrupolar field. These effects have been investigated experimentally with a beam of metastable hydrogen atoms H*(2s), either by measuring the atom flux through a fixed slit or by scanning the beam profile through a movable hole. The results are in good agreement with the theoretical predictions.
Quantum Interference between Transverse Spatial Waveguide Modes
Mohanty, Aseema; Dutt, Avik; Ramelow, Sven; Nussenzveig, Paulo; Lipson, Michal
2016-01-01
Integrated quantum optics has drastically reduced the size of table-top optical experiments to the chip-scale, allowing for demonstrations of large-scale quantum information processing and quantum simulation. However, despite these advances, practical implementations of quantum photonic circuits remain limited because they consist of large networks of waveguide interferometers that path encode information which do not easily scale. Increasing the dimensionality of current quantum systems using higher degrees of freedom such as transverse spatial field distribution, polarization, time, and frequency to encode more information per carrier will enable scalability by simplifying quantum computational architectures, increasing security and noise tolerance in quantum communication channels, and simulating richer quantum phenomena. Here we demonstrate a scalable platform for photonic quantum information processing using waveguide quantum circuit building blocks based on the transverse spatial mode degree of freedom:...
Transverse Instabilities in the FERMILAB Recycler
Prost, L R; Shemyakin, A; Bhat, C M; Crisp, J; Eddy, N
2012-01-01
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.
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.
Transverse momentum distributions and nuclear effects
Directory of Open Access Journals (Sweden)
Pace Emanuele
2015-01-01
Full Text Available A distorted spin-dependent spectral function for 3He is considered to take care of the final state interaction in the extraction of the quark transverse-momentum distributions in the neutron from semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers. The generalization of the analysis in a Poincaré covariant framework within the light-front dynamics is outlined. The definition of the light-front spin-dependent spectral function for a J=1/2 system, as the nucleon, allows us to show that within the light-front dynamics and in the valence approximation only three of the six leading twist T-even transverse-momentum distributions are independent.
Transverse nucleon structure and multiparton interactions
Strikman, Mark
2011-01-01
The transverse structure of the nucleon as probed in hard exclusive processes plays critical role in the understanding of the structure of the underlying event in hard collisions at the LHC, and multiparton interactions. We summarize results of our recent studies of manifestation of transverse nucleon structure in the hard collisions at the LHC, new generalized parton distributions involved in multiparton interactions, presence of parton fluctuations. The kinematic range where interaction of fast partons of the projectile with the target reach black disk regime (BDR) strength is estimated. We demonstrate that in the BDR postselection effect leads to effective fractional energy losses. This effect explains regularities of the single and double forward pion production in $ dAu$ collisions at RHIC and impacts on the forward physics in $pp$ collisions at the LHC.
Trans-dimensional ambient noise tomography of the northeast Asia
Kim, Seongryong; Tkalčić, Hrvoje; Rhie, Junkee; Chen, Youlin
2016-04-01
A trans-dimensional and hierarchical Bayesian tomography is performed to estimate spatial variations of shear wave velocity and provide the uncertainty in the northeast Asia region from the ambient noise data. The method accounts for irregular data distribution and sensitivity using adaptive partition property of Voronoi cells. Importantly, the number of basis functions used to parameterise the Earth model in the inversion and the level of data noise are implicitly balanced by the information contained in the data (and treated as free parameters in the inversions). Thereby more reliable models and their rigorous uncertainties are estimated by avoiding over- or under-estimation and explicit regularisation. We measure Rayleigh wave phase and group velocity (8-70 s) for available inter-station paths between more than 300 broadband stations. The obtained group and phase velocity maps reveal characteristic features beneath the former (East Sea also known as Japan Sea) and the current back-arc (Okinawa trough) regions, where relatively high and low velocities are estimated at intermediate (20-40 s) and longer periods (50-60 s), respectively. We observe that the low velocity anomalies extend to beneath intraplate volcanoes in the northeast China and the Korean Peninsula. Based on the depth sensitivity of surface wave dispersions and previous geological evidences, we argue that the intraplate volcanism in this region might be influenced by sub-lithospheric processes related to the subduction of the Pacific and Philippine Sea plates.
The space velocities of radio pulsars
Loginov, A. A.; Nikitina, E. B.; Malov, I. F.
2016-02-01
Known models proposed to explain the high space velocities of pulsars based on asymmetry of the transport coefficients of different sorts of neutrinos or electromagnetic radiation can be efficient only in the presence of high magnetic fields (to 1016 G) or short rotation periods for the neutron stars (of the order of 1 ms). This current study shows that the observed velocities are not correlated with either the pulsar periods or their surface magnetic fields. The initial rotation periods are estimated in a model for the magnetedipolar deceleration of their spin, aßsuming that the pulsar ages are equal to their kinematic ages. The initial period distribution is bimodal, with peaks at 5 ms and 0.5 s, and similar to the current distribution of periods. It is shown that asymmetry of the pulsar electromagnetic radiation is insufficient to give rise to additional acceleration of pulsars during their evolution after the supernova explosion that gave birth to them. The observations testify to deceleration of the motion, most likely due to the influence of the interstellar medium and interactions with nearby objects. The time scale for the exponential decrease in the magnetic field τ D and in the angle between the rotation axis and magnetic moment τ ß are estimated, yielding τ β = 1.4 million years. The derived dependence of the transverse velocity of a pulsar on the angle between the line of sight and the rotation axis of the neutron star corresponds to the expected dependence for acceleration mechanisms associated with asymmetry of the radiation emitted by the two poles of the star.
Erosion waves: transverse instabilities and fingering
Malloggi, F.; Lanuza, J.; Andreotti, B.; Clément, E.
2005-01-01
Two laboratory scale experiments of dry and under-water avalanches of non-cohesive granular materials are investigated. We trigger solitary waves and study the conditions under which the front is transversally stable. We show the existence of a linear instability followed by a coarsening dynamics and finally the onset of a fingering pattern. Due to the different operating conditions, both experiments strongly differ by the spatial and time scales involved. Nevertheless, the quantitative agree...
Partonic Picture of Generalized Transverse Momentum Distributions
Liuti, Simonetta; Courtoy, Aurore; Goldstein, Gary R.; Hernandez, J. Osvaldo Gonzalez; Rajan, Abha(University of Virginia – Physics Department, 382 McCormick Rd., Charlottesville, VA 22904, USA)
2013-01-01
We argue that due to parity constraints, the helicity combination of the purely momentum space counterparts of the Wigner distributions -- the generalized transverse momentum distributions -- that describes the configuration of an unpolarized quark in a longitudinally polarized nucleon, can enter the deeply virtual Compton scattering amplitude only through matrix elements involving a final state interaction. The relevant matrix elements in turn involve light cone operators projections in the ...
Transversity from First Principles in QCD
Brodsky, Stanley J.
2011-01-01
Transversity observables, such as the T-odd single-spin asymmetry measured in deep inelastic lepton scattering on polarized protons, and the distributions which are measured in deeply virtual Compton scattering provide important constraints on the fundamental quark and gluon structure of the proton. In this talk I discuss the challenge of computing these observables from first principles; i.e., quantum chromodynamics, itself. A key step is the determination of the frame-independent light-fron...
Ferrimagnetic behaviors in a transverse Ising nanoisland
Kaneyoshi, T.
2016-05-01
In this paper, the phase diagrams and magnetizations of a magnetic nanoisland described by the transverse Ising model (TIM) are investigated by the use of the effective-field theory (EFT) with correlations. A lot of characteristic behaviors observed in standard ferrimagnetic materials as well as novel phenomena have been obtained, although the system consists of two finite spin-1/2 layers coupled antiferromagnetically with a negative interlayer coupling.
Broadband transverse electric surface wave in silicene
Ukhtary, M. Shoufie; Nugraha, Ahmad R. T.; Hasdeo, Eddwi H.; Saito, Riichiro
2016-08-01
Transverse electric (TE) surface wave in silicine is theoretically investigated. The TE surface wave in silicene is found to exhibit better characteristics compared with that in graphene, in terms of a broader frequency range and more confinement to the surface which originate from the buckled structure of silicene. We found that even undoped silicene can support the TE surface wave. We expect the similar characteristics of the TE surface wave in other two-dimensional materials that have a slightly buckled honeycomb lattice.
MRI of sequela of transverse myelitis
Energy Technology Data Exchange (ETDEWEB)
Chen, W.C.; Lee, S.K.; Ho, Y.J. (Taichung Veterans General Hospital (Taiwan). Dept. of Radiology); Lee, K.R. (National Tsing-Hua Univ., Hsin-Chu (Taiwan). Inst. of Life Science); Mak, S.C.; Chi, C.S. (Taichung Veterans General Hospital (Taiwan). Dept. of Pediatrics)
1992-09-01
A 4-year-old boy developed acute paraplegia, associated with sensory impairement and bowel and urinary dysfunction after an URI. MRI showed diffuse hyperintensity in T2WI in the spinal cord below the T6 level. Acute transverse myelitis was diagnosed based on the clinical presentations and MRI findings. The patient had poor recovery and two months later, a follow-up MRI disclosed a severer diffuse atrophic change of the spinal cord in the affected segment. (orig.).
Diagnosis of longitudinally extensive transverse myelitis
Nightingale, Helen; Witherick, Jonathan; Wilkins, Alastair
2011-01-01
Longitudinally extensive transverse myelitis (LETM) is a neurological condition characterised by a contiguous inflammatory lesion of the spinal cord. LETM is often associated with the autoimmune central nervous system disease neuromyelitis optica (NMO) and rarely with multiple sclerosis. The discovery of the NMO-IgG antibody, provides a useful serological marker of LETM associated with the NMO disease spectrum (LETM and/or optic neuritis). Here, the authors report two cases of LETM, which dif...
Myelitis or transverse myelopathy. A case presentation.
Directory of Open Access Journals (Sweden)
Rubén Bembibre Taboada
2005-08-01
Full Text Available Here is presented a brief information about the most relevant aspects of myelitis or transverse myelopathy, a syndrome of low frequency rates in our medical experience with intensive care, along with an assisted case in our clinic intensive therapy service. The patient was subjected to the diverse complementary tests, necessary for the diagnosis, and she received established treatment for this process, and so for the complications presented. It was proved a fulminant ascendant myelitis with unfavourable fast evolution.
Myelitis or transverse myelopathy. A case presentation.
Rubén Bembibre Taboada; Dianarelys Villafuerte Delgado; Annia Alvarado Borges; Niurka Galende Hernández
2005-01-01
Here is presented a brief information about the most relevant aspects of myelitis or transverse myelopathy, a syndrome of low frequency rates in our medical experience with intensive care, along with an assisted case in our clinic intensive therapy service. The patient was subjected to the diverse complementary tests, necessary for the diagnosis, and she received established treatment for this process, and so for the complications presented. It was proved a fulminant ascendant myelitis with ...
MRI of sequela of transverse myelitis
International Nuclear Information System (INIS)
A 4-year-old boy developed acute paraplegia, associated with sensory impairement and bowel and urinary dysfunction after an URI. MRI showed diffuse hyperintensity in T2WI in the spinal cord below the T6 level. Acute transverse myelitis was diagnosed based on the clinical presentations and MRI findings. The patient had poor recovery and two months later, a follow-up MRI disclosed a severer diffuse atrophic change of the spinal cord in the affected segment. (orig.)
Theoretical Overview on Recent Developments in Transverse Spin Physics
Yuan, Feng
2009-01-01
Transverse-spin physics has been very active and rapidly developing in the last few years. In this talk, I will briefly summarize recent theoretical developments, focusing on the associated QCD dynamics in transverse spin physics.
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...
A New CERN PS Transverse Damper
Blas, A; Benedetto, E; Caspers, Friedhelm; Glenat, D C; Louwerse, R; Martini, M; Métral, E; Rossi, V; Sladen, J
2010-01-01
Since 1999 the PS has been operated without active transverse damping thanks to an increase of the coupling between the transverse planes and the reduction of injection steering errors. Although the LHC requirements are met by these means, a new transverse feedback system has been commissioned to reinforce the robustness of operation and avoid the blow-up generated by residual injection steering errors. This system could also allow the reduction of the chromaticity and reduce the slow incoherent losses during the long PS injection plateau. It could also stabilize the high energy instabilities that appear occasionally with the LHC nominal beam and may be a limiting factor for ultimate LHC beam. Highlights include a signal processing with an automatic delay adapting itself to the varying revolution frequency, a programmable betatron phase adjustment along the cycle, pick-ups that have been re-furbished with electronics covering the very low frequency of the first betatron line and a compact wideband high-power ...
Viscoelasticity of Tendons Under Transverse Compression.
Paul Buckley, C; Samuel Salisbury, S T; Zavatsky, Amy B
2016-10-01
Tendons are highly anisotropic and also viscoelastic. For understanding and modeling their 3D deformation, information is needed on their viscoelastic response under off-axis loading. A study was made, therefore, of creep and recovery of bovine digital extensor tendons when subjected to transverse compressive stress of up to ca. 100 kPa. Preconditioned tendons were compression tested between glass plates at increasing creep loads. The creep response was anomalous: the relative rate of creep reduced with the increasing stress. Over each ca. 100 s creep period, the transverse creep deformation of each tendon obeyed a power law dependence on time, with the power law exponent falling from ca. 0.18 to an asymptote of ca. 0.058 with the increasing stress. A possible explanation is stress-driven dehydration, as suggested previously for the similar anomalous behavior of ligaments. Recovery after removal of each creep load was also anomalous. Relative residual strain reduced with the increasing creep stress, but this is explicable in terms of the reducing relative rate of creep. When allowance was made for some adhesion occurring naturally between tendon and the glass plates, the results for a given load were consistent with creep and recovery being related through the Boltzmann superposition principle (BSP). The tendon tissue acted as a pressure-sensitive adhesive (PSA) in contact with the glass plates: explicable in terms of the low transverse shear modulus of the tendons. PMID:27496279
Superparamagnetism and dynamic transverse susceptibility in magnetic
Spinu, L.; Srikanth, H.; O'Connor, C. J.
2000-03-01
Dynamic transverse susceptibility (\\chi _T) measurements yield important information about spin dynamics in magnetic materials. They also provide a very sensitive and unique way to probe the magnetic anisotropy in novel systems like nanoparticles. We have developed a resonant method based on a tunnel-diode oscillator (TDO) operating at around 5 MHz to accurately measure the variation in dynamic transverse susceptibility over a wide range in temperature (5K to 300K) and static magnetic fields (0 to 9 T). Our experiments on magnetic nanoparticles (γ -Fe_2O_3/Ag nanocomposites), synthesized using reverse-micelle technique, reveal singular peaks in the low temperature transverse susceptibility at characteristic anisotropy fields (± 400 Oe). As the temperature is increased, the peaks evolve from being asymmetric to symmetric and eventually disappear at high temperatures well into the superparamagnetic regime. For the first time, we have mapped the complete variation of \\chi T in the H-T plane. We have also theoretically analyzed our results based on coherent rotation and find good agreement with a two-level model developed by us that includes thermal relaxation effects. This work is supported by DARPA through grant No. MDA 972-97-1-003
Performance of velocity vector estimation using an improved dynamic beamforming setup
DEFF Research Database (Denmark)
Munk, Peter; Jensen, Jørgen Arendt
2001-01-01
Estimation of velocity vectors using transverse spatial modulation has previously been presented. Initially, the velocity estimation was improved using an approximated dynamic beamformer setup instead of a static combined with a new velocity estimation scheme.(1) A new beamformer setup for dynami...... for four different flow angles (50, 60, 75 and 90 degrees). The velocity vector is calculated using the improved 2-D estimation approach at a range of depths.......Estimation of velocity vectors using transverse spatial modulation has previously been presented. Initially, the velocity estimation was improved using an approximated dynamic beamformer setup instead of a static combined with a new velocity estimation scheme.(1) A new beamformer setup for dynamic...... is simulated. The flow setup in the simulation is based on a vessel with a parabolic flow profile for a 60 and a 90-degree flow angle. The experimental results are based on the backscattered signal from a sponge mounted in a stepping device. The bias and std. dev. of the velocity estimate are calculated...
Experimental Investigation of the Velocity Effect on Adhesion Forces with an Atomic Force Microscope
Institute of Scientific and Technical Information of China (English)
魏征; 赵亚溥
2004-01-01
Capillary forces are significantly dominant in adhesive forces measured with an atomic force microscope (AFM)in ambient air, which are always thought to be dependent on water film thickness, relative humidity, and the free energy of water film. We study the nature of the pull-off force on a variety of surfaces as a function of tip velocity.It is found that the capillary forces are of relatively strong dependence on tip velocity. The present experiment is expected to provide a better understanding of the work mechanism of AFM in ambient air.
Influence of scanning velocity on femtosecond laser direct writing lines on FOTURAN glass
Institute of Scientific and Technical Information of China (English)
Yinzhong Wu; Ching-Yue Wang; Wei Jia; Xiaochang Ni; Minglie Hu; Lu Chai
2008-01-01
Lines are induced on the surface of a photosensitive (FOTURAN) glass by focused femtosecond laser transverse writing with scanning velocity in a wide range of 40- 1800μm/s. The formed lines are analyzed using scanning electron microscope (SEM) and optical microscope (OM). It is observed that three distinct morphologies of lines are produced depending on the scanning velocity. Lines written in low velocity level (40 - 100 μm/s) and high velocity level (1000 - 1800 μm/s) are uniform and regular, while those written in moderate velocity level (150 - 600 μm/s) are rough. The influence of scanning velocity is explained based on different pulses overlapping or cumulative dose of laser exposure in irradiated area. Fabrication of shallow groove on the surface is also demonstrated.
Soffer bound and transverse spin densities from lattice QCD
International Nuclear Information System (INIS)
Generalized transversity distributions encode essential information on the internal structure of hadrons related to transversely polarized quarks. Lattice QCD allows us to compute the lowest moments of these tensor generalized parton distributions. In this talk, we discuss a first lattice study of the Soffer bound and show preliminary results for transverse spin densities of quarks in the nucleon. (orig.)
Longitudinal and transverse polarizations in the deep inelastic reactions
International Nuclear Information System (INIS)
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.)
Transport Mean Free Path for Magneto-Transverse Light Diffusion
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.
Imprints of energy limitation in transverse momentum distributions of jets
Rybczyński, Maciej; Włodarczyk, Zbigniew
2015-01-01
Using a Tsallis nonextensive approach, we analyse distributions of transverse spectra of jets. We discuss the possible influence of energy conservation laws on these distributions. Transverse spectra of jets exhibit a power-law behavior of $1/p_T^n$ with the power indices $n$ similar to those for transverse spectra of hadrons.
Imprints of energy limitation in transverse momentum distributions of jets
International Nuclear Information System (INIS)
Using the Tsallis nonextensive approach, we analyse distributions of transverse spectra of jets. We discuss the possible influence of energy conservation laws on these distributions. Transverse spectra of jets exhibit a power-law behavior of 1/pT n with the power indices n similar to those for transverse spectra of hadrons. (orig.)
Physical modeling of transverse drainage mechanisms
Douglass, J. C.; Schmeeckle, M. W.
2005-12-01
Streams that incise across bedrock highlands such as anticlines, upwarps, cuestas, or horsts are termed transverse drainages. Their relevance today involves such diverse matters as highway and dam construction decisions, location of wildlife corridors, better-informed sediment budgets, and detailed studies into developmental histories of late Cenozoic landscapes. The transient conditions responsible for transverse drainage incision have been extensively studied on a case-by-case basis, and the dominate mechanisms proposed include: antecedence, superimposition, overflow, and piracy. Modeling efforts have been limited to antecedence, and such the specific erosional conditions required for transverse drainage incision, with respect to the individual mechanisms, remains poorly understood. In this study, fifteen experiments attempted to simulate the four mechanisms and constructed on a 9.15 m long, 2.1 m wide, and 0.45 m deep stream table. Experiments lasted between 50 and 220 minutes. The stream table was filled with seven tons of sediment consisting of a silt and clay (30%) and a fine to coarse sand (70%) mixture. The physical models highlighted the importance of downstream aggradation with regard to antecedent incision versus possible defeat and diversion. The overflow experiments indicate that retreating knickpoints across a basin outlet produce a high probability of downstream flooding when associated with a deep lake. Misters used in a couple of experiments illustrate a potential complication with regard to headward erosion driven piracy. Relatively level asymmetrically sloped ridges allow for the drainage divide across the ridge to retreat from headward erosion, but hindered when the ridge's apex undulates or when symmetrically sloped. Although these physical models cannot strictly simulate natural transverse drainages, the observed processes, their development over time, and resultant landforms roughly emulate their natural counterparts. Proposed originally from
Transverse electron beam diagnostics at REGAE
International Nuclear Information System (INIS)
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
Transverse electron beam diagnostics at REGAE
Energy Technology Data Exchange (ETDEWEB)
Bayesteh, Shima
2014-12-15
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
Historical Ambient Air Quality Data Inventory
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...
Regional Ambient Noise Tomography in the Eastern Alps of Europe
Behm, Michael; Nakata, Nori; Bokelmann, Götz
2016-08-01
We present results from ambient noise tomography applied to temporary seismological stations in the easternmost part of the Alps and their transition to the adjacent tectonic provinces (Vienna Basin, Bohemian Massif, Southern Alps, Dinarides). By turning each station into a virtual source, we recover surface waves in the frequency range between 0.1 and 0.6 Hz, which are sensitive to depths of approximately 2-15 km. The utilization of horizontal components allows for the analysis of both Rayleigh and Love waves with comparable signal-to-noise ratio. Measured group wave dispersion curves between stations are mapped to local cells by means of a simultaneous inverse reconstruction technique. The spatial reconstruction for Love-wave velocities fails in the central part of the investigated area, and we speculate that a heterogeneous noise source distribution is the cause for the failure. Otherwise, the obtained group velocity maps correlate well with surface geology. Inversion of Rayleigh-wave velocities for shear-wave velocities along a vertical N-S section stretching from the Bohemian Massif through the Central Alps to the Southern Alps and Dinarides reveals a mid-crustal low-velocity anomaly at the contact between the Bohemian Massif and the Alps, which shows a spatial correlation with the P-wave velocity structure and the low-frequency component of the magnetic anomaly map. Our study is validated by the analysis of resolution and accuracy, and we further compare the result to shear-wave velocity models estimated from other active and passive experiments in the area.
Sand transverse dune aerodynamics: 3D Coherent Flow Structures from a computational study
Bruno, Luca
2015-01-01
The engineering interest about dune fields is dictated by the their interaction with a number of human infrastructures in arid environments. The aerodynamic behaviour of sand dunes in atmospheric boundary layer belongs to the class of bluff bodies. Because of their simple geometry and their frequent occurrence in desert area, transverse sand dunes are usually adopted in literature as a benchmark to investigate dune aerodynamics by means of both computational or experimental approach, usually in nominally 2D setups. The writers suspect the flow in the wake is characterised by 3D features and affected by wind tunnel setup - e.g. blockage effect, duct side wall boundary layer, incoming velocity profile - when experimental studies are carried out. The present study aims at evaluating the 3D flow features of an idealised transverse dune under different setup conditions by means of computational simulations and to compare the obtained results with experimental measurements.
Structural lubricity under ambient conditions
Cihan, Ebru; İpek, Semran; Durgun, Engin; Baykara, Mehmet Z.
2016-01-01
Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000–130,000 nm2) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold–graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions. PMID:27350035
Fiscalidad ambiental (curso 2011-2012)
Gil Maciá, Lorenzo
2012-01-01
Tema fiscalidad ambiental. 1. Necesidad económica y jurídica de la protección del medio ambiente. 2. Características, naturaleza y clasificación de los tributos ambientales. 3. Competencias tributarias en el ámbito estatal, autonómico y local. 4. La fiscalidad ambiental en la legislación fiscal española. 5. Perspectivas de futuro en materia de imposición ambiental.
[Ambient assisted living - an overview].
Christiansen, St; Klötzer, J-P
2015-09-01
Ambient assisted living (AAL) technologies are mainly developed to support elderly people in their own homes and facilitate a longer, self-determined life. In addition to providing a demographic prognosis for Germany, the present publication includes the definition, classification and current market situation of AAL. Lastly, the benefit of AAL technologies to the insurance industry and the subsequent steps to be taken are addressed. PMID:26548006
Crumpling under an ambient pressure
Lin, Y C; Wang, Y. L.; Liu, Y; Hong, T.M.
2008-01-01
A pressure chamber is designed to study the crumpling process under an ambient force. The compression force and its resulting radius for the ball obey a power law with an exponent that is independent of the thickness and initial size of the sheet. However, the exponent is found to be material-dependent and less than the universal value, 0.25, claimed by the previous simulations. The power law behavior disappears at high pressure when the compressibility drops discontinuously, which is suggest...
Hypermedia in the Ambient Wood
Weal, Mark J; Michaelides, Danius T.; Thompson, Mark K.; De Roure, David C
2003-01-01
The Ambient Wood project, carried out as part of the Equator IRC, set out to provide an augmented learning experience for children in an outdoor environment. Using a variety of devices, the children gathered information about the woodland habitats performing basic scientific enquiry and hypothesis testing. In this paper we describe the supporting information infrastructure used in the project, focusing on how hypermedia tools and techniques were used to structure and deliver the information t...
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.
International Nuclear Information System (INIS)
The field scale tracer tests were carried out with a non-reactive tracer of 131I at Twin Lake on the Chalk River Laboratory (CRL) site in Atomic Energy of Canada Limited (AECL). The natural gradient dispersion test such as the Twin Lake tracer test is very few and useful for evaluating mass transport parameters and testing groundwater flow and transport models. In this report, mass transport parameters, velocity, longitudinal and transverse dispersivities, were estimated from the Twin Lake 40 m tracer tests. This estimation was performed to provide dispersion data for 3-D transport modelling in the Lake 233 site scale (600 m in east-west direction and 1400 m in north-south direction). Two different methods were applied to the measured breakthrough curves of 131I in order to evaluate velocity and longitudinal dispersivity. The first method is the fitting procedure of the 1-D advection-dispersion solution, and the second one is the temporal moments analysis. The effect of applying these methods to field data on transport parameters was discussed in this study. The vertical profiles of 131I were used in the estimation of transverse dispersivity by fitting the 3-D advection-dispersion solution. This report refereed to the effect of variable velocity on the estimated dispersivities. The correlation between magnitude of both dispersivities and the travel distance up to 40 m was also investigated. (author)
Quantum deflagration in Mn12-acetate in the presence of a transverse field
Subedi, Pradeep; Velez, Saul; Li, Shiqi; Sarachik, Myriam; Tejada, Javier; Kent, Andrew; Mukherjee, Shreya; Christou, George
2012-02-01
Mn12-acetate single crystal have been shown to exhibit abrupt reversal of the magnetic moment through propagation of a narrow front at subsonic velocities, termed magnetic deflagration [1]. Experiments where avalanches in Mn12-acetate are triggered at a fixed applied field have shown that the velocity of the front has maxima at resonant fields (kHo, Ho = 0.45 T, k>1), due to thermally assisted tunneling of magnetization [2]. Application of a transverse field increases the tunnel splitting, which increases the magnetic relaxation and allows us to explore the deflagration for the first time at small longitudinal fields (k=0 and 1). Using time resolved measurements of local magnetization by an array of micron sized Hall sensors at temperature of 350 mK, we present the measurements on both spontaneously ignited and triggered deflagration for a large transverse field (> 3 T) allowing us to explore directly the effect of a significant tunneling splitting on both the ignition and the velocity of the front. [1] Y. Suzuki, et. al PRL 95, 147201 (2005) [2] A. Hernandez-Minguez, et. al, PRL 95, 217205 (2005)
Ambient noise tomography across the southern Alaskan Cordillera
Ward, Kevin M.
2015-05-01
I present the results of an extensive data mining effort integrating 197 permanent and temporary seismic stations into a Rayleigh wave ambient noise study across southern Alaska and westernmost Canada. Principal observations of my tomography model are largely consistent with mapped geology features and previous geophysical studies while providing previously unavailable, laterally continuous details of the southern Alaskan Cordillera lithosphere. At intermediate periods, a geophysically uniform crust is observed north of the Denali Fault and is consistent with a sharp transition in crustal thickness. Under the Wrangell volcanic belt, a prominent low-phase-velocity anomaly correlates well with the lateral extent of a relative low-gravity anomaly and Neogene surface volcanics. At longer periods, a low-phase-velocity anomaly bounds the inferred eastern extent of the subducted Yakutat microplate beneath the Wrangell volcanic belt.
Angular velocity spread of relativistic photoelectrons induced by excimer laser irradiation
Energy Technology Data Exchange (ETDEWEB)
Kawai, M.; Kawamura, Y.; Toyoda, K.
1984-12-15
The angular velocity spread of relativistic photoelectrons induced by a pulsed excimer laser was measured. The energy, the current density, and the pulse duration of the accelerated photoelectron were 0.34 MeV, 0.5 A/cm/sup 2/, and 20 ns, respectively. (The method of measurement is based on measuring Larmor radius which corresponds to the transverse component of the electron velocity.)= The angular velocity spread ..beta../sub perpendicular//..beta../sub parallel/ was found to be less than 8 x 10/sup -3/, which means that the energy component due to ..beta../sub perpendicular/ was as small as < or approx. =17 eV.
The transverse field Richtmyer-Meshkov instability in magnetohydrodynamics
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.
Kinetic damping of transverse waves in a homogeneous magnetized plasma
International Nuclear Information System (INIS)
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)
Factors influencing perceived angular velocity
Kaiser, Mary K.; Calderone, Jack B.
1991-01-01
Angular velocity perception is examined for rotations both in depth and in the image plane and the influence of several object properties on this motion parameter is explored. Two major object properties are considered, namely, texture density which determines the rate of edge transitions for rotations in depth, i.e., the number of texture elements that pass an object's boundary per unit of time, and object size which determines the tangential linear velocities and 2D image velocities of texture elements for a given angular velocity. Results of experiments show that edge-transition rate biased angular velocity estimates only when edges were highly salient. Element velocities had an impact on perceived angular velocity; this bias was associated with 2D image velocity rather than 3D tangential velocity. Despite these biases judgements were most strongly determined by the true angular velocity. Sensitivity to this higher order motion parameter appeared to be good for rotations both in depth (y-axis) and parallel to the line of sight (z-axis).
Analysis of velocity derivatives in turbulence based on generalized statistics
Arimitsu, N.; Arimitsu, T.
2002-10-01
A theoretical formula for the probability density function (PDF) of velocity derivatives in a fully developed turbulent flow is derived with the multifractal aspect based on the generalized measures of entropy, i.e., the extensive Rényi entropy or the non-extensive Tsallis entropy, and is used, successfully, to analyze the PDFs observed in the direct numerical simulation (DNS) conducted by Gotoh et al. The minimum length scale rd/η in the longitudinal (transverse) inertial range of the DNS is estimated to be rdL/η = 1.716 (rdT/η = 2.180) in the unit of the Kolmogorov scale η.
Velocity bunching in travelling wave accelerator with low acceleration gradient
Huang, Rui-Xuan; Li, Wei-Wei; Jia, Qi-Ka
2013-01-01
We present the analytical and simulated results concerning the influences of the acceleration gradient in the velocity bunching process, which is a bunch compression scheme that uses a traveling wave accelerating structure as a compressor. Our study shows that the bunch compression application with low acceleration gradient is more tolerant to phase jitter and more successful to obtain compressed electron beam with symmetrical longitudinal distribution and low energy spread. We also present a transverse emittance compensation scheme to compensate the emittance growth caused by the increasing of the space charge force in the compressing process that is easy to be adjusted for different compressing factors.
Estimation of velocity vectors in synthetic aperture ultrasound imaging
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt; Oddershede, Niels
2006-01-01
normalized correlation calculated as a function of angle. This assumes the flow direction is within the imaging plane. Simulations of the angle estimation method show both biases and standard deviations of the flow angle estimates below 3 deg for flow angles from 20 deg to 90 deg (transverse flow...... of the visually determined flow angle. The standard deviation of these estimates was below 2.7 deg. Full color flow maps from different parts of the cardiac cycle are presented, including vector arrows indicating both estimated flow direction and velocity magnitude....
Particle Velocity Measuring System
Arndt, G. Dickey (Inventor); Carl, James R. (Inventor)
1998-01-01
Method and apparatus are provided for determining the velocity of individual food particles within a liquid/solid food mixture that is cooked by an aseptic cooking method whereby the food mixture is heated as it flows through a flowline. At least one upstream and at least one downstream microwave transducer are provided to determine the minimum possible travel time of the fastest food particle through the flowline. In one embodiment, the upstream detector is not required. In another embodiment, a plurality of small dipole antenna markers are secured to a plurality of food particles to provide a plurality of signals as the markers pass the upstream and downstream transducers. The dipole antenna markers may also include a non-linear element to reradiate a harmonic frequency of a transmitter frequency. Upstream and downstream transducers include dipole antennas that are matched to the impedance of the food slurry and a signal transmission cable by various impedance matching means including unbalanced feed to the antennas.
Velocity dependant splash behaviour
Hamlett, C. A. E.; Shirtcliffe, N. J.; McHale, G.; Ahn, S.; Doerr, S. H.; Bryant, R.; Newton, M. I.
2012-04-01
Extreme soil water repellency can occur in nature via condensation of volatile organic compounds released during wildfires and can lead to increased erosion rate. Such extreme water repellent soil can be classified as superhydrophobic and shares similar chemical and topographical features to specifically designed superhydrophobic surfaces. Previous studies using high speed videography to investigate single droplet impact behaviour on artificial superhydrophobic have revealed three distinct modes of splash behaviour (rebound, pinned and fragmentation) which are dependent on the impact velocity of the droplet. In our studies, using high-speed videography, we show that such splash behaviour can be replicated on fixed 'model' water repellent soils (hydrophobic glass beads/particles). We show that the type of splash behaviour is dependent on both the size and chemical nature of the fixed particles. The particle shape also influences the splash behaviour as shown by drop impact experiments on fixed sand samples. We have also studied soil samples, as collected from the field, which shows that the type of droplet splash behaviour can lead to enhanced soil particle transport.
Lesage, Philippe; Reyes-Dávila, G.; Arámbula-Mendoza, R.
2014-01-01
International audience We used the ambient noise cross-correlation and stretching methods to calculate variations in seismic velocities in the region of Volcán de Colima, Mexico. More than 15 years of continuous records were processed, producing long time series of velocity variations related to volcanic activity, meteorological effects, and earthquakes. Velocity variations associated with eruptive activity are tenuous, which probably reflects the open state of the volcano during the study...
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...... stored on the experimental scanner SARUS. The full 3-D velocity profile can be created and examined at peak-systole and end-diastole without ECG gating in two planes. Maximum out-of-plane velocities for the three peak-systoles and end-diastoles were 68.5 5.1 cm/s and 26.3 3.3 cm/s, respectively. 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...
MR imaging of alar and transverse atlantal ligament injuries
International Nuclear Information System (INIS)
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.)
Ferrofluid Lubrication of a Rough Porous Hyperbolic Slider Bearing with Slip Velocity
Directory of Open Access Journals (Sweden)
S.J. Patel
2014-09-01
Full Text Available An attempt has been made to study and analyze the combined effect of roughness and slip velocity on the performance of a ferrofluid based rough porous hyperbolic slider bearing. Beavers and Joseph’s slip model has been used to evaluate the effect of slip velocity. The stochastic modeling of Christensen and Tonder has been employed to estimate the effect of transverse surface roughness. The associated Reynolds’ type equation is solved with suitable boundary conditions to obtain the pressure distribution leading to the calculation of load carrying capacity. Further, the expressions for friction and position of centre of pressure are obtained. It is observed that the bearing system gets adversely affected by the transverse surface roughness. The slip velocity further enhances this adverse effect. However, the magnetization saves the situation in the case of negatively skewed roughness when variance (-ve occurs. But for an overall improved performance of the bearing the lower values of slip parameter may be favorable.
Experiments on the critical ionization velocity interaction in weak magnetic fields
International Nuclear Information System (INIS)
The critical ionization velocity interaction is studied experimentally in a configuration with a magnetized plasma stream colliding with a stationary neutral gas cloud. In all previous experiment of this kind the magnetic field (1) has had a component transverse to the plasma flow and (2) has been strong in the sense that the electron gyro frequency, has exceeded or been approximately equal to the plasma frequency. Both these conditions play an important role in existing theories of the critical velocity interaction. The present experiments are performed to determine whether or not such interaction is possible when one of these conditions is not fulfilled, namely when the magnetic field is weak. Experiments have been performed both with a transverse and longitudinal (aligned with the plasma flow) magnetic field. It is found that in both cases the critical ionization velocity effect either disappears or becomes too small to be distinguishable among classical collisional processes. (author)
Generating catalogs of transverse matching solutions
International Nuclear Information System (INIS)
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
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.
Velocities of Reacting Boron Particles within a Solid Fuel Ramjet Combustion Chamber
Sender, J.; H.K. Ciezki
1998-01-01
A 2D-laser doppler velocimeter was used to measure velocities of reacting boron (B) particles during the combustion of a metallised solid fuel slab inside a 20-combustion chamber. The solid fuel hydroxyl-terminated polybutadiene (HTPB) was enriched with B particles to increase its specific heat. To obtain information on the combustion process and on the movement of B particles, their velocities were measured. The experiments were performed at ambient pressure. The behaviour of the B pa...
Park, Suhyeon
2015-01-01
This work will report the non-intrusive sensing of air velocity, humidity, and temperature using tunable diode laser absorption spectroscopy (TDLAS), and discuss the potential applications of such sensors for in situ monitoring and active control for wind energy. The sensing technique utilizes the absorption features of water vapor in ambient air to monitor multiple flow parameters including velocity, humidity, and temperature simultaneously and non-intrusively [1-3]. The TDLAS technique does...
Melamed, Timor; Abuhasira, Dor; Dayan, David
2012-06-01
The present contribution is concerned with applying beam-type expansion to a planar aperture time-dependent (TD) electromagnetic field in which the propagating elements, the electromagnetic pulsed-beams, are a priori decomposed into transverse electric (TE) and transverse magnetic (TM) field polarizations. The propagating field is described as a discrete superposition of tilted, shifted, and delayed TE and TM electromagnetic pulsed-beam propagators over the frame spectral lattice. These waveobjects are evaluated by using TD plane-wave spectral representations. Explicit asymptotic expressions for electromagnetic isodiffracting pulsed-quadratic beam propagators are presented, as well as a numerical example. PMID:22673443
Ridge and Transverse Correlation at Separated Rapidities
Chiu, Charles B
2012-01-01
A simple phenomenological relationship between the ridge distribution in $\\Delta\\eta$ and the single-particle distribution in $\\eta$ can be established from the PHOBOS data on both distributions. The implication points to the possibility that there is no long-range longitudinal correlation. An interpretation of the relationship is then developed, based on the recognition that longitudinal uncertainty of the initial configuration allows for non-Hubble-like expansion at early time. It is shown that the main features of the ridge structure can be explained in a model where transverse correlation stimulated by semihard partons is the principal mechanism.
Transverse beam dampers for the Brookhaven AGS
International Nuclear Information System (INIS)
A wide band damper system has been developed for the Brookhaven Alternating Gradient Synchrotron (AGS). The system consists of two sets of PUE pickups, analog and digital processing electronics, four 500 Watt wide band power amplifiers, and two pairs of strip line deflectors. The system is currently used to damp transverse coherent instabilities and injection errors, in both planes, for protons and all species of Heavy Ions. This paper discusses the system design and operation, focusing on the engineering considerations and problems encountered in the actual implementation. Operational data from both protons and Heavy Ion beams is presented
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.
Summary report on transverse emittance preservation
International Nuclear Information System (INIS)
During the past years, significant progress has been made in understanding the beam transverse emittance blow-up and its preservation. However, one often finds him-/herself ignorant when he/she tries to explain what was observed in an existing machine or to predict what will happen in a machine under design. There are a number of such examples given in this report. Some of them are even fundamental. These are the challenges. But they are also the directions leading to new achievements. The workshop gladly acknowledged them and promised to work on them
The transversely split gracilis twin free flaps
Directory of Open Access Journals (Sweden)
Upadhyaya Divya
2010-01-01
Full Text Available The gracilis muscle is a Class II muscle that is often used in free tissue transfer. The muscle has multiple secondary pedicles, of which the first one is the most consistent in terms of position and calibre. Each pedicle can support a segment of the muscle thus yielding multiple small flaps from a single, long muscle. Although it has often been split longitudinally along the fascicles of its nerve for functional transfer, it has rarely been split transversely to yield multiple muscle flaps that can be used to cover multiple wounds in one patient without subjecting him/her to the morbidity of multiple donor areas .