Results 21 to 30 of about 54,131 (295)

Realizing normal group-velocity dispersion in free space via angular dispersion [PDF]

Optics Letters, 2021
It has long been thought that normal group-velocity dispersion (GVD) cannot be produced in free space via angular dispersion. Indeed, conventional diffractive or dispersive components such as gratings or prisms produce only anomalous GVD. We identify the conditions that must be fulfilled by the angular dispersion introduced into a plane-wave pulse to ...
Layton A. Hall, Ayman F. Abouraddy
openaire   +3 more sources

Theoretical Re-evaluations of Scaling Relations between SMBHs and Their Host Galaxies–2. Importance of AGN Feedback Suggested by Stellar Age–Velocity Dispersion Relation

Frontiers in Astronomy and Space Sciences, 2017
We present the galactic stellar age—velocity dispersion relation obtained from a semi-analytic model of galaxy formation. We divide galaxies into two populations: galaxies which have over-massive/under-massive black holes (BHs) against the best-fitting ...
Hikari Shirakata, Toshihiro Kawaguchi, Takashi Okamoto, Tomoaki Ishiyama   +3 more
doaj   +1 more source

Tight gas detection based on the reflectivity dispersion technology

Petroleum Exploration and Development, 2014
The study focuses on the reflectivity dispersion caused by velocity dispersion related to pore fluid and its application to identify tight gas reservoirs.
Zhifang YANG, Hong CAO, Huizhu YANG, Xinfei YAN   +3 more
doaj   +1 more source

Influence of Physical Parameters of Coal Seam on “Cross” Phenomenon of Rayleigh In-seam Wave Dispersion Curve

Meikuang Anquan, 2020
Dispersion curves of Rayleigh channel waves may have “cross” between the fundamental and first higher order modes either in the phase velocities or in group velocities in the low frequency band.
HE Daxi, ZHU Peimin, SHEN Suishui, CAI Wei, WANG Wengang
doaj   +1 more source

Biases in the estimation of velocity dispersions and dynamical masses for galaxy clusters [PDF]

EPJ Web of Conferences, 2020
Using a set of 73 numerically simulated galaxy clusters, we have characterised the statistical and physical biases for three velocity dispersion and mass estimators, namely biweight, gapper and standard deviation, in the small number of galaxies regime ...
Ferragamo A., Rubiño-Martín J.A., Betancort-Rijo J., Munari E., Sartoris B., Barrena R.   +5 more
doaj   +1 more source

EXPERIMENTAL STUDY OF LIQUID DISPERSION IN BUBBLE COLUMN

Diyala Journal of Engineering Sciences, 2008
The main object of this study is to investigate the influence of column diameter and superficial gas velocity on liquid phase dispersion coefficients (axial and radial dispersion coefficients), mixing times, gas holdup, and bubble dynamics (bubble ...
Hayder Abd Al-kaream Muhsin
doaj   +1 more source

Nonlinear FAVO Dispersion Quantification Based on the Analytical Solution of the Viscoelastic Wave Equation

Geofluids, 2020
Wave-induced fluid flow is the main cause of seismic attenuation and dispersion. So the estimated velocity dispersion information can be used to identify reservoir fluid and effectively reduce the risk of reservoir drilling.
Yuanqiang Li, Jingye Li, Xiaohong Chen, Jian Zhang, Chen Zhou, Wei Tang   +5 more
doaj   +1 more source

Hydraulic permeability prediction from attenuation in an oil well using the squirt flow model

Geofísica Internacional
A practical methodology is presented for estimating the hydraulic permeability from the wave attenuation at sonic frequencies using the poroelastic squirt flow model associated with the mechanism that encompasses the interaction between solid and fluid ...
Joseline Mena-Negrete, Raúl Del Valle García, Enrique Coconi-Morales   +2 more
doaj   +1 more source

Velocity Dispersion of Ionized Gas and Multiple Supernova Explosions

Open Astronomy, 2015
We use 3D numerical simulations to study the evolution of the Hα intensity and velocity dispersion for single and multiple supernova (SN) explosions. We find that the IHα– σ diagram obtained for simulated gas flows is similar in shape to that observed in
Vasiliev E. O., Moiseev A. V., Shchekinov Yu. A.   +2 more
doaj   +1 more source

Properties of individual S-bursts observed in the frequency band of 10–32 MHz during the rising phase of 25-th solar cycle

Frontiers in Astronomy and Space Sciences
Introduction: The properties of the S-bursts observed during the storm on 20–21 June 2022 in frequency band 10–32 MHz by the radio telescope URAN-2 are discussed in this paper.
V. V. Dorovskyy, V. N. Melnik, A. I. Brazhenko, A. V. Frantsuzenko   +3 more
doaj   +1 more source