[1] We have investigated the influence of continental lids on mantle convective stirring efficiency using numerical experiments and analytical theory at infinite Prandtl number with strong temperature dependence of viscosity. Differences between oceans and continents are accounted for by imposing heterogeneous surface boundary conditions for temperature and velocity. We measure the convective stirring efficiency using mixing times and Lyapunov exponent distribution. We quantify systematically the influence of the Rayleigh number, the horizontal extent of continental lids and the rheology on mantle convective stirring efficiency. The presence of continents increases the mantle temperature and therefore reduces mantle viscosity. This in turn leads to an increase of convective vigor and results in a drastic enhancement (3-6 fold, and possibly up two orders of magnitude increase) of mantle convective stirring efficiency.
We developed an integrated method that can better constrain subsalt tomography using geology, thermal history modeling, and rock-physics principles. This method, called rock-physics-guided velocity modeling for migration uses predicted pore pressure as a guide to improve the quality of the earth model. We first generated a rock-physics model that provided a range of plausible pore pressure that lies between hydrostatic (lowest possible pressure) and fracture pressure (highest possible pressure). The range of plausible pore pressures was then converted into a range of plausible depth varying velocities as a function of pore pressure that is consistent with geology and rock physics. Such a range of plausible velocities is called the rock-physics template. Such a template (constrained by geology) was then used to flatten the seismic gathers. We call this the pore-pressure scan technique. The outcome of the pore-pressure scan process was an “upper” and “lower” bound of pore pressure for a given earth model. Such velocity bounds were then used as constraints on the subsequent tomography, and further iterations were carried out. The integrated method not only flattened the common image point gathers but also limited the velocity field to its physically and geologically plausible range without well control; for example, in the study area it produced a better image and pore-pressure prognosis below salt. We determined that geologic control is essential, and we used it for stratigraphy, structure, and unconformity, etc. The method had several subsalt applications in the Gulf of Mexico and proved that subsalt pore pressure can be reliably predicted.
<p>Secondary propulsion methods for high-speed hyperloop transportation are sparsely researched. Secondary propulsion methods are essential to quickly, efficiently, and safely get a hyperloop pod up to its target speed from a stationary state. In this paper, we propose and analyze the feasibility of a form of electromagnetic secondary hyperloop propulsion, called a railgun, commonly used in modern-day artillery technology for high-speed ammunition launching. We assess the feasibility of two different materials and three different geometries for a railgun armature to propel a hyperloop pod. Inverse design of multiphysics simulation of multibody dynamics, magnetic fields, and electric currents are used for material selection of the armature that minimizes rail current energy requirements and the armature geometry that maximizes structural integrity.</p>
SUMMARYWe present a workflow using geology in conjunction with thermal history modelling and rock physics principles for velocity modelling and imaging is presented. A novel feature of this workflow is to use predicted pore pressure as a guide to improve the quality of Earth model. Thus, we are not only flattens the CIP gathers (a necessary imaging condition) but also limits the velocity field to its physically and geologically plausible range without well control.This has yielded both improved image and more accurate pore pressure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.