Wave-equation migration using one-way wavefield extrapolation operators is commonly used in industry to generate images of complex geologic structure from 3D seismic data. By design, most conventional wave-equation approaches restrict propagation to downward continuation, where wavefields are recursively extrapolated to depth on Cartesian meshes. In practice, this approach is limited in high-an...

BACKGROUND Before extracting impacted lower third molars, dentists must first identify the spatial relationship between the inferior alveolar nerve (IAN) and an impacted lower third molar to prevent nerve injury from the extraction. Nevertheless, the current method for describing the spatial relationship between the IAN and an impacted lower third molar is deficient. Therefore, the objectives o...

Pei Chen1, Xiucong Sun2, and Chao Han3 Beihang University, Beijing, 100191, People’s Republic of China Nomenclature U = gravitational potential, m2/s2 T = gravity gradient tensor (GGT), E TECEF = GGT in ECEF, E TENU = GGT in ENU, E TEIG = GGT in the Eigen frame, E T0 = GGT in GRF, E LA→B = rotation matrix from A to B r = observation position, m x, y, z = cartesian coordinates of r r, φ, λ = sph...

Purpose – Aims to clarify the use of “nuclear” robots with special reference to one UK contractor (Magnox) and the cost-effectiveness of its decommissioning programme. Design/methodology/approach – Goes through the protocol of the use of robots in the disposal of contaminated scrap. Findings – Justifies the use of a built-to-order modular linear (Cartesian) robot system required by Magnox. Orig...

Abstract: In this paper, a prototype Cartesian Parallel Manipulator (CPM) is demonstrated, in which a moving platform is connected to a fixed frame by three PRRR limbs. Due to the orthogonal arrangement of the three prismatic joints, it behaves like a conventional X-Y-Z Cartesian robot. However, because all the linear actuators are mounted at the fixed frame, the manipulator may be suitable for...

Visualizing functions is an omnipresent task in many sciences and almost every day we are confronted with diagrams in newspapers and magazines showing functions of all possible flavours. Usually such functions are visualized by plotting their function graph inside an appropriate coordinate system, with the probably most prominent choice being the cartesian coordinate system. This allows us to g...

In this paper, we propose a novel method for face recognition which uses the polar coordinate system instead of the conventional cartesian coordinate system. Among the central area of a face, we select a point as a pole and make a polar image of a face by evenly sampling pixels in each direction of 360 degrees around the pole. The polar coordinate system delineates near-pole area more vividly t...

Riemannian wavefield extrapolation is a technique for one-way extrapolation of acoustic waves. Riemannian wavefield extrapolation generalizes wavefield extrapolation by downward continuation by considering coordinate systems different from conventional Cartesian ones. Coordinate systems can conform with the extrapolated wavefield, with the velocity model or with the acquisition geometry. When c...