Conventional velocity analysis applied to images produced by wave-equation migration with a cross-correlation imaging condition makes use either of moveout information from space-lags or of focusing information from time-lags. However, more robust velocity estimation methods can be designed to take advantage simultaneously of the moveout and focusing information provided by the migrated images....

Wavefield extrapolation in the (ω−x) domain provides a tool for depth migration with strong lateral variations in velocity. Implicit formulations of depth extrapolation have several advantages over explicit methods. However, the simple 3-D extension of conventional 2-D wavefield extrapolation by implicit finite-differencing requires the inversion of a 2-D convolution matrix which is computation...

Strong, sharp, negative seismic discontinuities, velocity decreases with depth, are observed beneath the Pacific seafloor at ∼60 km depth. It has been suggested that these are caused by an increase in radial anisotropy with depth, which occurs in global surface wave models. Here we test this hypothesis in two ways. We evaluate whether an increase in surface wave radial anisotropy with depth is ...

We demonstrate a method for 2D velocity estimation in complex media characterized by triplicated ray fields. Due to multipathing, Migration Velocity Analysis (MVA) principle has to be revisited, requiring in particular the use of Common Angle Gathers (CAGs) instead of the classical common offset panels. For the inversion itself, locally coherent events are automatically picked in the prestack d...

bendway weirs are an important tool in multi-purpose erosion control and are implemented to control erosion, restore streams, and improve habitat. these structures create a hydraulic effect that reduces erosion on the outer bank of a bend by reducing flow velocities near the outer bank and reduce the concentration of currents on the outer bank creating better current alignment through the bend....

Surface granular flow, comprising granular material flowing on the surface of a heap of the same material, occurs in several industrial and natural systems. The rheology of such flow is investigated by means of measurements of velocity and number density profiles in a quasi-two-dimensional rotating cylinder, half-filled with a model granular material mono-size spherical stainless steel particle...

Scour in the downstream of hydraulic structures is a phenomenon which usually occurs due to exceeding the velocity or shear stress from a critical level. In this paper by using the laboratory data by Borman- Jouline and De-Agostino research, it was tried to get more accurate equations in order to calculate the maximum depth of scour in the downstream of the water level regulation structures. Co...

We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities, Coweeta Creek sculpin sh...