We tackle the problem of characterizing the subsurface, more specifically detecting shallow buried objects, using seismic techniques. This problem is commonly encountered in civil engineering when cavities or pipes have to be identified from the surface in urban areas. Our strategy consists of processing not only first arrivals, but also later ones, and using them both in tomography and migrati...

A new ray-based approach for converting multicomponent normal moveout uncorrected offset domain prestack seismic data into angles is presented. From any two-way zero-offset time sample and a given angle of incidence, the exact ray and a few neighboring rays that contribute to the given angle of incidence are traced through the medium to their corresponding source and receiver locations to compu...

Historically though, 3D marine streamer acquisition has been forced to compromise spatial sampling in the name of efficiency and cost. This compromise translates to noise and degraded resolution when processing the data. A significant component of the seismic “noise” contaminating 3D images actually arises during processing, as an unfortunate and inescapable artifact from poor 3D spatial sampli...

Migration velocity analysis (MVA) is an approach to solve a partially linearized variant of the waveform inversion problem, i.e. linear in short scales, nonlinear in long scales. The linear inversion part is often approximated by migration in practice, which is only adjoint of linearized Born modeling operator. In this abstract, we derive the gradient formulas for short scales and long scales s...

Abstract. Two high-resolution seismic reflection profiles acquired north and south of Chibougamau, located in the northeast Abitibi subprovince Canada, help understand historic volcanically hosted massive sulfide (VMS) deposits hydrothermal Cu–Au mineralization found there. Major faults crossed by include Barlow fault Doda Guercheville south, all targets this study that seeks to determine spati...

The objective of this work is to build an efficient algorithm (a) to estimate seismic velocity from time-migration velocity, and (b) to convert time-migrated images to depth. We establish theoretical relations between the time-migration velocity and the seismic velocity in 1 Page 1 of 23 GEOPHYSICS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 3...

This study investigated the extent to which individual differences in working memory (WM) mediate effects of captions with or without textual enhancement on attentional allocation and L2 grammatical development, whether development is influenced by WM absence captions. We employed a pretest-posttest-delayed posttest design, 72 Korean learners English randomly assigned three groups. The groups d...

Background & objectives: Polyethylene terephthalate (PET) containers have many applications in the food industry. Although there are numerous advantages for PET it also has some disadvantages, one of which is the migration of materials from the container into the material inside. In this study, the effect of two factors of storage time and temperature on the migration rate was evaluated and mod...

Surface plasmon waveguides (SPW’s) are metal ridges featuring widths in the micrometre range and thicknesses of a few tens of nanometres. A focused ion beam (FIB) has been used to carve micro–scatterers into gold SPW’s and the near–field distributions around these micro-structures are observed by means of a Photon Scanning Tunneling Microscope (PSTM). On the basis of near-field images, we show ...

Reading difficulties are found in children with both high and low IQ and it is now clear that both groups exhibit difficulties in phonological processing. Here, we apply the developmental trajectories approach, a new methodology developed for studying language and cognitive impairments in developmental disorders, to both poor reader groups. The trajectory methodology enables identification of a...