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Статті в журналах з теми "Velocity difference"

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Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 28 січня 2023

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1

Strumpf, C., M. L. Braunstein, C. W. Sauer, and G. J. Andersen. "Velocity difference and velocity ratio in structure-from-motion." Journal of Vision 1, no. 3 (March 15, 2010): 330. http://dx.doi.org/10.1167/1.3.330.

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2

Ristow, Dietrich, and Thomas Rühl. "Fourier finite‐difference migration." GEOPHYSICS 59, no. 12 (December 1994): 1882–93. http://dx.doi.org/10.1190/1.1443575.

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Анотація:

Many existing migration schemes cannot simultaneously handle the two most important problems of migration: imaging of steep dips and imaging in media with arbitrary velocity variations in all directions. For example, phase‐shift (ω, k) migration is accurate for nearly all dips but it is limited to very simple velocity functions. On the other hand, finite‐difference schemes based on one‐way wave equations consider arbitrary velocity functions but they attenuate steeply dipping events. We propose a new hybrid migration method, named “Fourier finite‐difference migration,” wherein the downward‐continuation operator is split into two downward‐continuation operators: one operator is a phase‐shift operator for a chosen constant background velocity, and the other operator is an optimized finite‐difference operator for the varying component of the velocity function. If there is no variation of velocity, then only a phase‐shift operator will be applied automatically. On the other hand, if there is a strong variation of velocity, then the phase‐shift component is suppressed and the optimized finite‐difference operator will be fully applied. The cascaded application of phase‐shift and finite‐difference operators shows a better maximum dip‐angle behavior than the split‐step Fourier migration operator. Depending on the macro velocity model, the Fourier finite‐difference migration even shows an improved performance compared to conventional finite‐difference migration with one downward‐continuation step. Finite‐difference migration with two downward‐continuation steps is required to reach the same migration performance, but this is achieved with about 20 percent higher computation costs. The new cascaded operator of the Fourier finite‐difference migration can be applied to arbitrary velocity functions and allows an accurate migration of steeply dipping reflectors in a complex macro velocity model. The dip limitation of the cascaded operator depends on the variation of the velocity field and, hence, is velocity‐adaptive.

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3

Coombs, Earl. "Demonstrating the difference between velocity and acceleration." Physics Teacher 28, no. 8 (November 1990): 546–47. http://dx.doi.org/10.1119/1.2343146.

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4

WANG, Tao, and Jing ZHANG. "Property Analysis of Multiple Velocity Difference Model." Systems Engineering - Theory & Practice 28, no. 10 (October 2008): 150–55. http://dx.doi.org/10.1016/s1874-8651(10)60005-1.

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5

Braunstein, Myron L., Craig W. Sauer, Cary Strumpf Feria, and George J. Andersen. "Perceived Internal Depth in Rotating and Translating Objects." Perception 31, no. 8 (August 2002): 943–54. http://dx.doi.org/10.1068/p3294.

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Previous research has indicated that observers use differences between velocities and ratios of velocities to judge the depth within a moving object, although depth cannot in general be determined from these quantities. In four experiments we examined the relative effects of velocity difference and velocity ratio on judged depth within a transparent object that was rotating about a vertical axis and translating horizontally, examined the effects of the velocity difference for pure rotations and pure translations, and examined the effect of the velocity difference for objects that varied in simulated internal depth. Both the velocity difference and the velocity ratio affected judged depth, with difference having the larger effect. The effect of velocity difference was greater for pure rotations than for pure translations. Simulated depth did not affect judged depth unless there was a corresponding change in the projected width of the object. Observers appear to use the velocity difference, the velocity ratio, and the projected width of the object heuristically to judge internal object depth, rather than using image information from which relative depth could potentially be recovered.

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6

Zhou, Jie, and Zhong-Ke Shi. "A modified full velocity difference model with the consideration of velocity deviation." International Journal of Modern Physics C 27, no. 06 (May 13, 2016): 1650069. http://dx.doi.org/10.1142/s0129183116500698.

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In this paper, a modified full velocity difference model (FVDM) based on car-following theory is proposed with the consideration of velocity deviation which represents the inexact judgement of velocity. The stability condition is obtained by the use of linear stability analysis. It is shown that the stability of traffic flow varies with the deviation extent of velocity. The Burgers, Korteweg-de Vries (KdV) and modified K-dV (MKdV) equations are derived to describe the triangular shock waves, soliton waves and kink–antikink waves in the stable, metastable and unstable region, respectively. The numerical simulations show a good agreement with the analytical results, such as density wave, hysteresis loop, acceleration, deceleration and so on. The results show that traffic congestion can be suppressed by taking the positive effect of velocity deviation into account. By taking the positive effect of high estimate of velocity into account, the unrealistic high deceleration and negative velocity which occur in FVDM will be eliminated in the proposed model.

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7

Min, I. A., I. Mezić, and A. Leonard. "Lévy stable distributions for velocity and velocity difference in systems of vortex elements." Physics of Fluids 8, no. 5 (May 1996): 1169–80. http://dx.doi.org/10.1063/1.868908.

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8

Brooks, K. R. "Interocular velocity difference contributes to stereomotion speed perception." Journal of Vision 2, no. 3 (April 1, 2002): 2. http://dx.doi.org/10.1167/2.3.2.

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9

Ersson, Mikael. "Colocated pressure-velocity coupling in finite difference methods." Progress in Computational Fluid Dynamics, An International Journal 19, no. 5 (2019): 273. http://dx.doi.org/10.1504/pcfd.2019.10022961.

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10

Ersson, Mikael. "Colocated pressure-velocity coupling in finite difference methods." Progress in Computational Fluid Dynamics, An International Journal 19, no. 5 (2019): 273. http://dx.doi.org/10.1504/pcfd.2019.102037.

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11

Boldyrev, S. A. "Velocity-difference probability density functions for Burgers turbulence." Physical Review E 55, no. 6 (June 1, 1997): 6907–10. http://dx.doi.org/10.1103/physreve.55.6907.

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12

Akatsuka, Fumihiro, and Yoshihiko Nomura. "Velocity difference perception in passive elbow flexion movement." Proceedings of Conference of Tokai Branch 2017.66 (2017): 321. http://dx.doi.org/10.1299/jsmetokai.2017.66.321.

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13

Du, Yixue, Bruce J. Ackerson, and Penger Tong. "Velocity difference measurement with a fiber-optic coupler." Journal of the Optical Society of America A 15, no. 9 (September 1, 1998): 2433. http://dx.doi.org/10.1364/josaa.15.002433.

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14

Gong, Huaxin, Hongchao Liu, and Bing-Hong Wang. "An asymmetric full velocity difference car-following model." Physica A: Statistical Mechanics and its Applications 387, no. 11 (April 2008): 2595–602. http://dx.doi.org/10.1016/j.physa.2008.01.038.

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15

Yan-Fei, Jin, and Xu Meng. "Bifurcation Analysis of the Full Velocity Difference Model." Chinese Physics Letters 27, no. 4 (April 2010): 040501. http://dx.doi.org/10.1088/0256-307x/27/4/040501.

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16

Wang Tao, Gao Zi-You, and Zhao Xiao-Mei. "Multiple velocity difference model and its stability analysis." Acta Physica Sinica 55, no. 2 (2006): 634. http://dx.doi.org/10.7498/aps.55.634.

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17

Ou, Zhong-Hui, Shi-Qiang Dai, and Li-Yun Dong. "Density waves in the full velocity difference model." Journal of Physics A: Mathematical and General 39, no. 6 (January 24, 2006): 1251–63. http://dx.doi.org/10.1088/0305-4470/39/6/003.

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18

Fomel, Sergey. "Time‐migration velocity analysis by velocity continuation." GEOPHYSICS 68, no. 5 (September 2003): 1662–72. http://dx.doi.org/10.1190/1.1620640.

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Анотація:

Time‐migration velocity analysis can be performed by velocity continuation, an incremental process that transforms migrated seismic sections according to changes in the migration velocity. Velocity continuation enhances residual normal moveout correction by properly taking into account both vertical and lateral movements of events on seismic images. Finite‐difference and spectral algorithms provide efficient practical implementations for velocity continuation. Synthetic and field data examples demonstrate the performance of the method and confirm theoretical expectations.

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19

Ding, Heyu, Pengfei Zhao, Han Lv, Xiaoshuai Li, Xiaoyu Qiu, Rong Zeng, Guopeng Wang, et al. "Correlation Between Trans-Stenotic Blood Flow Velocity Differences and the Cerebral Venous Pressure Gradient in Transverse Sinus Stenosis: A Prospective 4-Dimensional Flow Magnetic Resonance Imaging Study." Neurosurgery 89, no. 4 (June 25, 2021): 549–56. http://dx.doi.org/10.1093/neuros/nyab222.

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Abstract BACKGROUND The relationship between trans-stenotic blood flow velocity differences and the cerebral venous pressure gradient (CVPG) in transverse sinus (TS) stenosis (TSS) has not been studied. OBJECTIVE To evaluate the hemodynamic manifestations of TSS and the relationship between trans-stenotic blood flow velocity differences and the CVPG. METHODS Thirty-three patients with idiopathic intracranial hypertension (IIH) or pulsatile tinnitus (PT) and TSS who had undergone diagnostic venography using venous manometry were included in the patient group. Thirty-three volunteers with no stenosis and symptoms were included in the control group. All the 2 groups underwent prospective venous sinus 4-dimensional (4D) flow magnetic resonance imaging (MRI). The average velocity (Vavg) difference and maximum velocity (Vmax) difference between downstream and upstream of the TS in 2 groups were measured and compared. Correlations between the CVPG and trans-stenotic Vavg difference/Vmax difference/index of transverse sinus stenosis (ITSS) were assessed in the patient group. RESULTS The differences in Vavg difference and Vmax difference between the patient and control groups showed a statistical significance (P < .001). The Vavg difference and Vmax difference had a strong correlation with CVPG (R = 0.675 and 0.701, respectively, P < .001) in the patient group. Multivariate linear regression using the stepwise method showed that the Vmax difference and ITSS were correlated with the CVPG (R = 0.752 and R2 = 0.537, respectively; P < .001). CONCLUSION The trans-stenotic blood flow velocity difference significantly correlates with the CVPG in TSS. As a noninvasive imaging modality, 4D flow MRI may be a suitable screening or complimentary tool to decide which TSS may benefit from invasive venous manometry.

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20

Browne, Rodrigo Alberto Vieira, Marcelo Magalhães Sales, Rafael da Costa Sotero, Ricardo Yukio Asano, José Fernando Vila Nova de Moraes, Jônatas de França Barros, Carmen Sílvia Grubert Campbell, and Herbert Gustavo Simões. "Critical velocity estimates lactate minimum velocity in youth runners." Motriz: Revista de Educação Física 21, no. 1 (March 2015): 1–7. http://dx.doi.org/10.1590/s1980-65742015000100001.

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In order to investigate the validity of critical velocity (CV) as a noninvasive method to estimate the lactate minimum velocity (LMV), 25 youth runners underwent the following tests: 1) 3,000m running; 2) 1,600m running; 3) LMV test. The intensity of lactate minimum was defined as the velocity corresponding to the lowest blood lactate concentration during the LMV test. The CV was determined using the linear model, defined by the inclination of the regression line between distance and duration in the running tests of 1,600 and 3,000m. There was no significant difference (p=0.3055) between LMV and CV. In addition, both protocols presented a good agreement based on the small difference between means and the narrow levels of agreement, as well as a standard error of estimation classified as ideal. In conclusion, CV, as identified in this study, may be an alternative for noninvasive identification of LMV.

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21

Tessmer, Ekkehart. "Seismic finite‐difference modeling with spatially varying time steps." GEOPHYSICS 65, no. 4 (July 2000): 1290–93. http://dx.doi.org/10.1190/1.1444820.

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Numerical seismic modeling by finite‐difference methods usually works with a global time‐step size. Because of stability considerations, the time‐step size is determined essentially by the highest seismic velocity, i.e., the higher the highest velocity, the smaller the time step needs to be. Therefore, if large velocity contrasts exist within the numerical grid, domains of low velocity are oversampled temporally. Using different time‐step sizes in different parts of the numerical grid can reduce computational costs considerably.

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22

Zhang, Xue, He Ming Cheng, Jian Yun Li, Si Qing Zhou, and Tie Xin Yang. "Numerical Simulation of Pressure Difference about Curve Ball in Flight." Applied Mechanics and Materials 444-445 (October 2013): 505–8. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.505.

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Life lies in movement, Football is now the most popular sport in the world. Fluent12.1 software is employed in this thesis to model the numerical simulation of the pressure which the ball with different angular velocity and different velocity bears. Simulation results show that the pressure difference on the surface of the ball with a certain speed will increase if the angular velocity increases. The pressure difference on the surface of the ball with a certain angular velocity will increase if the velocity increases. The radian of ball will become more bigger.

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23

Aoi, Shin, and Hiroyuki Fujiwara. "3D finite-difference method using discontinuous grids." Bulletin of the Seismological Society of America 89, no. 4 (August 1, 1999): 918–30. http://dx.doi.org/10.1785/bssa0890040918.

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Abstract We have formulated a 3D finite-difference method (FDM) using discontinuous grids, which is a kind of multigrid method. As long as uniform grids are used, the grid size is determined by the shortest wavelength to be calculated, and this constitutes a significant constraint on the introduction of low-velocity layers. We use staggered grids that consist of, on one hand, grids with fine spacing near the surface where the wave velocity is low, and on the other hand, grids whose spacing is three times coarser in the deeper region. In each region, we calculated the wavefield using a velocity-stress formulation of second-order accuracy and connected these two regions with linear interpolations. The second-order finite-difference (FD) approximation was used for updating. Since we did not use interpolations for updating, the time increments were the same in both regions. The use of discontinuous grids adapted to the velocity structure resulted in a significant reduction of computational requirements, which is model dependent but typically one-fifth to one-tenth, without a marked loss of accuracy.

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24

Bajewski, Łukasz, Aleksander Wilk, and Andrzej Urbaniec. "Porównanie modeli prędkości obliczonych z wykorzystaniem różnych wariantów prędkości i algorytmów na profilu sejsmicznym 2D na potrzeby migracji czasowej po składaniu." Nafta-Gaz 77, no. 7 (July 2021): 419–28. http://dx.doi.org/10.18668/ng.2021.07.01.

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This article presents a construction method of the velocity field for poststack time migration for 2D seismic calculated on the basis of interval velocities in boreholes and structural interpretation, as well as the results of poststack time migration based on this solution. Three velocity field models have been developed. The models used differ in the way of spatial interpolation and extrapolation in the adopted calculation grid in the depth domain, which was created on the basis of a structural interpretation of 2D seismic profiles. Three methods of interpolation and extrapolation were used: Gaussian distribution, kriging and moving average. The spatial distribution of the interval velocities in the boreholes was made using the Petrel software by Schlumberger. The interval velocities along the analyzed seismic profile were extracted from the computed spatial interval velocity models, and after conversion from the depth to the time domain, they were used for the poststack time migration. For comparison, poststack time migration was calculated for the same seismic profile based on the stacking velocities obtained in the seismic processing data as a result of velocity analyzes. The velocity field calculated on the basis of interval velocities and structural interpretation was used for the poststack time migration procedure performed with the Implicit FD Time Migration algorithm (finite difference), while the stacking velocities were used for the poststack time migration procedure performed with the Stolt and Kirchhoff algorithms in accordance with the technical conditions of correct operation of these algorithms. The selected percentage ranges of 60%, 100%, and 140% have been used for all velocity fields. Application of the element of directional velocity variation resulting from the spatial distribution of interval velocities in the boreholes to the velocity field for the poststack time migration allowed to obtain a better seismic image in relation to the one obtained as a result of applying the stacking velocities. The most reliable seismic image after poststack time migration was obtained for the velocity field calculated on the basis of the interval velocities with Gaussian distribution, using the finite difference algorithm with 60 percent value of the velocity field.

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25

Qian, Jianliang, and William W. Symes. "Finite‐difference quasi‐P traveltimes for anisotropic media." GEOPHYSICS 67, no. 1 (January 2002): 147–55. http://dx.doi.org/10.1190/1.1451438.

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The first‐arrival quasi‐P wave traveltime field in an anisotropic elastic solid solves a first‐order nonlinear partial differential equation, the q P eikonal equation. The difficulty in solving this eikonal equation by a finite‐difference method is that for anisotropic media the ray (group) velocity direction is not the same as the direction of the traveltime gradient, so that the traveltime gradient can no longer serve as an indicator of the group velocity direction in extrapolating the traveltime field. However, establishing an explicit relation between the ray velocity vector and the phase velocity vector overcomes this difficulty. Furthermore, the solution of the paraxial q P eikonal equation, an evolution equation in depth, gives the first‐arrival traveltime along downward propagating rays. A second‐order upwind finite‐difference scheme solves this paraxial eikonal equation in O(N) floating point operations, where N is the number of grid points. Numerical experiments using 2‐D and 3‐D transversely isotropic models demonstrate the accuracy of the scheme.

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26

Wiehr, E., G. Stellmacher, H. Balthasar, and M. Bianda. "Velocity Difference of Ions and Neutrals in Solar Prominences." Astrophysical Journal 920, no. 1 (October 1, 2021): 47. http://dx.doi.org/10.3847/1538-4357/ac1791.

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27

Zhi-Peng, Li, and Liu Yun-Cai. "A velocity-difference-separation model for car-following theory." Chinese Physics 15, no. 7 (July 2006): 1570–76. http://dx.doi.org/10.1088/1009-1963/15/7/032.

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28

Axel, Leon, and Daniel Morton. "MR Flow Imaging by Velocity-Compensated/Uncompensated Difference Images." Journal of Computer Assisted Tomography 11, no. 1 (January 1987): 31–34. http://dx.doi.org/10.1097/00004728-198701000-00006.

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29

Peng, G. H., X. H. Cai, C. Q. Liu, B. F. Cao, and M. X. Tuo. "Optimal velocity difference model for a car-following theory." Physics Letters A 375, no. 45 (October 2011): 3973–77. http://dx.doi.org/10.1016/j.physleta.2011.09.037.

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30

Moretti, P. F., and G. Severino. "The intensity-velocity phase difference with Magneto-Optical Filters." Astronomy & Astrophysics 384, no. 2 (March 2002): 638–49. http://dx.doi.org/10.1051/0004-6361:20020033.

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31

Ge, H. X., R. J. Cheng, and Z. P. Li. "Two velocity difference model for a car following theory." Physica A: Statistical Mechanics and its Applications 387, no. 21 (September 2008): 5239–45. http://dx.doi.org/10.1016/j.physa.2008.02.081.

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32

Jin, Sheng, Dianhai Wang, Pengfei Tao, and Pingfan Li. "Non-lane-based full velocity difference car following model." Physica A: Statistical Mechanics and its Applications 389, no. 21 (November 2010): 4654–62. http://dx.doi.org/10.1016/j.physa.2010.06.014.

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33

Yu, Shaowei, Jinjun Tang, and Qi Xin. "Relative velocity difference model for the car-following theory." Nonlinear Dynamics 91, no. 3 (December 12, 2017): 1415–28. http://dx.doi.org/10.1007/s11071-017-3953-8.

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34

Wang, Xiaolong, Yonghong Liu, and Yanzhen Zhang. "Velocity Difference of Aqueous Drop Bouncing Between Parallel Electrodes." Journal of Dispersion Science and Technology 36, no. 7 (July 17, 2014): 893–97. http://dx.doi.org/10.1080/01932691.2014.938161.

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35

Chmela, P., Z. Ficek, and S. Kielich. "Enhanced incoherent sum-frequency generation by group velocity difference." Optics Communications 62, no. 6 (June 1987): 403–8. http://dx.doi.org/10.1016/0030-4018(87)90008-3.

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36

Yao, Sheng-Hong, Viktor K. Horváth, Penger Tong, Bruce J. Ackerson, and Walter I. Goldburg. "Measurements of the instantaneous velocity difference and the local velocity with a fiber-optic coupler." Journal of the Optical Society of America A 18, no. 3 (March 1, 2001): 696. http://dx.doi.org/10.1364/josaa.18.000696.

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37

Larner, Ken, and Craig Beasley. "Cascaded migrations: Improving the accuracy of finite‐difference migration." GEOPHYSICS 52, no. 5 (May 1987): 618–43. http://dx.doi.org/10.1190/1.1442331.

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Анотація:

The accuracy of time migrations done with finite‐difference schemes deteriorates with increasing reflector dip. Some properties of migration in general, and of finite‐difference approaches in particular, suggest a way of improving the accuracy of finite‐difference schemes for migrating steep dips. First, although data will be undermigrated when too low a velocity is used in migration, a correctly migrated result can be obtained by migrating again, this time with the previously undermigrated result as input. In fact, a sequence of undermigrations will yield the correct result as long as the sum of the squares of the migration velocities used in the different migration stages equals the square of the correct migration velocity. A second property is that the apparent spatial dip of a reflector perceived by the migration process is a function of not only the time dip of the unmigrated reflection, but also the velocity used in the migration. In a sequence of low‐velocity migrations, the apparent spatial dip perceived at each migration stage can be considerably less than the true dip. Thus, because finite‐difference migration is accurate for small spatial dips, the cascaded migrations yield a more accurate result than that of single‐stage migration. Also, because each migration stage is done with low velocity, the depth step can be large; hence, the computational effort need not be. The accuracy of the method is not compromised (in fact, it improves) in media in which velocity increases with depth. Moreover, the cascaded approach suffers no more than other methods of time migration where velocity varies mildly in the lateral direction. In applications of the method to stacked data from the Gulf of Mexico, reflections from near‐vertical flanks of salt domes were migrated with accuracy comparable to that achieved by frequency‐wavenumber domain migration.

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38

Biondi, Biondo. "Stable wide‐angle Fourier finite‐difference downward extrapolation of 3‐D wavefields." GEOPHYSICS 67, no. 3 (May 2002): 872–82. http://dx.doi.org/10.1190/1.1484530.

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I present an unconditionally stable, implicit finite‐difference operator that corrects the constant‐velocity phase‐shift operator for lateral velocity variations. The method is based on the Fourier finite‐difference (FFD) method. Contrary to previous results, my correction operator is stable even when the medium velocity has sharp discontinuities, and the reference velocity is higher than the medium velocity. The stability of the new correction enables the definition of a new downward‐continuation method based on the interpolation of two wavefields: the first wavefield is obtained by applying the FFD correction starting from a reference velocity lower than the medium velocity; the second wavefield is obtained by applying the FFD correction starting from a reference velocity higher than the medium velocity. The proposed Fourier finite‐difference plus interpolation (FFDPI) method combines the advantages of the FFD technique with the advantages of interpolation. A simple and economical procedure for defining frequency‐dependent interpolation weight is presented. When the interpolation step is performed using these frequency‐dependent interpolation weights, it significantly reduces the residual phase error after interpolation, the frequency dispersion caused by the discretization of the Laplacian operator, and the azimuthal anisotropy caused by splitting. Tests on zero‐offset data from the SEG‐EAGE salt data set show that the FFDPI method improves the imaging of a fault reflection with respect to a similar interpolation scheme that uses a split‐step correction for adapting to lateral velocity variations.

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39

Qin, Fuhao, Yi Luo, Kim B. Olsen, Wenying Cai, and Gerard T. Schuster. "Finite‐difference solution of the eikonal equation along expanding wavefronts." GEOPHYSICS 57, no. 3 (March 1992): 478–87. http://dx.doi.org/10.1190/1.1443263.

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We show that a scheme to solve the 2-D eikonal equation by a finite‐difference method can violate causality for moderate to large velocity contrasts [Formula: see text]. As an alternative, we present a finite‐difference scheme in which the solution region progresses outward from an “expanding wavefront” rather than an “expanding square,” and therefore honors causality. Our method appears to be stable and reasonably accurate for a variety of velocity models with moderate to large velocity contrasts. The penalty is a large increase in computational cost and programming effort.

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40

Hossain, Md Anowar, K. M. Ariful Kabir, and Jun Tanimoto. "Improved Car-Following Model Considering Modified Backward Optimal Velocity and Velocity Difference with Backward-Looking Effect." Journal of Applied Mathematics and Physics 09, no. 02 (2021): 242–59. http://dx.doi.org/10.4236/jamp.2021.92018.

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41

Tatarskii, V. I., and A. Muschinski. "The difference between Doppler velocity and real wind velocity in single scattering from refractive index fluctuations." Radio Science 36, no. 6 (November 2001): 1405–23. http://dx.doi.org/10.1029/2000rs002376.

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42

Cao, Jinliang, Zhongke Shi, and Jie Zhou. "An extended optimal velocity difference model in a cooperative driving system." International Journal of Modern Physics C 26, no. 05 (March 25, 2015): 1550054. http://dx.doi.org/10.1142/s0129183115500540.

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An extended optimal velocity (OV) difference model is proposed in a cooperative driving system by considering multiple OV differences. The stability condition of the proposed model is obtained by applying the linear stability theory. The results show that the increase in number of cars that precede and their OV differences lead to the more stable traffic flow. The Burgers, Korteweg–de Vries (KdV) and modified Korteweg–de Vries (mKdV) equations are derived to describe the density waves in the stable, metastable and unstable regions, respectively. To verify these theoretical results, the numerical simulation is carried out. The theoretical and numerical results show that the stabilization of traffic flow is enhanced by considering multiple OV differences. The traffic jams can be suppressed by taking more information of cars ahead.

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43

Romagnoli, Ruggero, and Maria Francesca Piacentini. "Perception of Velocity during Free-Weight Exercises: Difference between Back Squat and Bench Press." Journal of Functional Morphology and Kinesiology 7, no. 2 (April 18, 2022): 34. http://dx.doi.org/10.3390/jfmk7020034.

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The perception of bar velocity (PV) is a subjective parameter useful in estimating velocity during resistance training. The aim of this study was to investigate if the PV can be improved through specific training sessions, if it differs between the back squat (SQ) and bench press (BP), and if there are differences in perception accuracy in the different intensity zones. Resistance-trained participants were randomly divided in an experimental (EG, n = 16) or a control group (CG, n = 14). After a familiarization trial, both groups were tested before and after 5 weeks of training. The PV was assessed with five blinded loads covering different intensity domains. During the training period, only the EG group received velocity feedback for each repetition. Prior to training, both groups showed a greater PV accuracy in the SQ than in the BP. Post training, the EG showed a significant reduction (p < 0.05) in the delta score (the difference between the real and perceived velocity) for both exercises, while no significant differences were observed in the CG. Prior to training, the perceived velocity was more accurate at higher loads for both exercises, while no difference between loads was observed after training (EG). The results of this study demonstrate that the PV improves with specific training and that differences in the accuracy between loads and exercise modes seen prior to training are leveled off after training.

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44

Liu, Yang. "Acoustic and elastic finite-difference modeling by optimal variable-length spatial operators." GEOPHYSICS 85, no. 2 (January 30, 2020): T57—T70. http://dx.doi.org/10.1190/geo2019-0145.1.

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Time-space domain finite-difference modeling has always had the problem of spatial and temporal dispersion. High-order finite-difference methods are commonly used to suppress spatial dispersion. Recently developed time-dispersion transforms can effectively eliminate temporal dispersion from seismograms produced by the conventional modeling of high-order spatial and second-order temporal finite differences. To improve the efficiency of the conventional modeling, I have developed optimal variable-length spatial finite differences to efficiently compute spatial derivatives involved in acoustic and elastic wave equations. First, considering that temporal dispersion can be removed, I prove that minimizing the relative error of the phase velocity can be approximately implemented by minimizing that of the spatial dispersion. Considering that the latter minimization depends on the wavelength that is dependent on the velocity, in this sense, this minimization is indirectly related to the velocity, and thus leads to variation of the spatial finite-difference operator with velocity for a heterogeneous model. Second, I use the Remez exchange algorithm to obtain finite-difference coefficients with the lowest spatial dispersion error over the largest possible wavenumber range. Then, dispersion analysis indicates the validity of the approximation and the algorithm. Finally, I use modeling examples to determine that the optimal variable-length spatial finite difference can greatly increase the modeling efficiency, compared to the conventional fixed-length one. Stability analysis and modeling experiments also indicate that the variable-length finite difference can adopt a larger time step to perform stable modeling than the fixed-length one for inhomogeneous models.

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45

Sakhaee, Farhad. "Finite Difference Method in Fluid Potential Function and Velocity Calculation." Brilliant Engineering 3, no. 2 (December 10, 2021): 1–4. http://dx.doi.org/10.36937/ben.2022.4519.

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There is no deterministic solution for many fluid problems but by applying analytical solutions many of them are approximated. In this study an implicit finite difference method presented which solves the potential function and further expanded to drive out the velocity components in 2D-space by applying a point-by-point swiping approach. The results showed the rotational behavior of both potential function as well as velocity components while encountering central obstacle.

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46

Lu, Daquan, Liejia Qian, Yongzhong Li, Hua Yang, Heyuan Zhu, and Dianyuan Fan. "Phase velocity nonuniformity-resulted beam patterns in difference frequency generation." Optics Express 15, no. 8 (April 11, 2007): 5050. http://dx.doi.org/10.1364/oe.15.005050.

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47

Reed, T. Edward, Philip A. Vernon, and Andrew M. Johnson. "Sex difference in brain nerve conduction velocity in normal humans." Neuropsychologia 42, no. 12 (January 2004): 1709–14. http://dx.doi.org/10.1016/j.neuropsychologia.2004.02.016.

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48

Rivas, Eric, Kyleigh N. Allie, Paolo M. Salvador, Lauren Schoech, and Mauricio Martinez. "Sex difference in cerebral blood flow velocity during exercise hyperthermia." Journal of Thermal Biology 94 (December 2020): 102741. http://dx.doi.org/10.1016/j.jtherbio.2020.102741.

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49

Hosokawa, Iwao, and Kiyoshi Yamamoto. "Statistics of Velocity Difference vs. Statisticsof Dissipation in Isotropic Turbulence." Journal of the Physical Society of Japan 60, no. 6 (June 15, 1991): 1852–55. http://dx.doi.org/10.1143/jpsj.60.1852.

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50

Nigam, R., and A. G. Kosovichev. "Phase and Amplitude Difference between Velocity and Intensity Helioseismic Spectra." Astrophysical Journal 510, no. 2 (January 10, 1999): L149—L152. http://dx.doi.org/10.1086/311809.

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