Sandia National Laboratories

About: Sandia National Laboratories is a facility organization based out in Livermore, California, United States. It is known for research contribution in the topics: Laser & Combustion. The organization has 21501 authors who have published 46724 publications receiving 1484388 citations. The organization is also known as: SNL & Sandia National Labs.

Phase encoding of shot records in prestack migration

Abstract: Frequency‐domain shot‐record migration can produce higher quality images than Kirchhoff migration but typically at a greater cost. The computing cost of shot‐record migration is the product of the number of shots in the survey and the expense of each individual migration. Many attempts to reduce this cost have focused on the speed of the individual migrations, trying to achieve a better trade‐off between accuracy and speed. Another approach is to reduce the number of migrations. We investigate the simultaneous migration of shot records using frequency‐domain shot‐record migration algorithms. The difficulty with this approach is the production of so‐called crossterms between unrelated shot and receiver wavefields, which generate unwanted artifacts or noise in the final image. To reduce these artifacts and obtain an image comparable in quality to the single‐shot‐per‐migration result, we have introduced a process called phase encoding, which shifts or disperses these crossterms. The process of phase encoding...

Physical Mechanisms Contributing to Device "Rebound"

Abstract: The physical mechanisms that produce rebound have been identified. The positive increase in threshold voltage during a bias anneal is due to annealing of oxide trapped charge. Rebound can be predicted by measuring the contribution to the threshold voltage from radiation-induced interface states immediately after irradiation.

Dynamics of irreversible island growth during submonolayer epitaxy.

Abstract: The nucleation and growth of two-dimensional islands during the submonolayer stage of epitaxial growth is studied with kinetic Monte Carlo simulations and mean-field rate equations. Previous work on irreversible growth is extended to include relaxation of island shapes by edge diffusion. Island morphologies range from ramified structures at low temperatures to compact, polygonal shapes at higher temperatures. Using a self-consistent calculation of the rate coefficients, [ital quantitative] agreement is obtained between the solution to coupled, mean-field rate equations and the simulation results for average quantities. The island size distribution function is described by a single universal scaling function.'' The average island size is the only important scale for determining island densities. It is shown that the general form of the scaling [ital ansatz] applies to wider range of coverages than anticipated previously. This scaling form is combined with the solution to the rate equations to explore explicitly the [ital D]/[ital F] dependence of the number density of islands ([ital D] is the surface diffusion coefficient and [ital F] is the deposition flux).

Dish-Stirling Systems: An Overview of Development and Status

Abstract: Dish-Stirling systems have demonstrated the highest efficiency of any solar power generation system by converting nearly 30% of direct-normal incident solar radiation into electricity after accounting for parasitic power losses [1]. These high-performance, solar power systems have been in development for two decades with the primary focus in recent years on reducing the capital and operating costs of systems. Even though the systems currently cost about $10,000 US/kW installed, major cost reduction will occur with mass production and further development of the systems. Substantial progress has been made to improve reliability thereby reducing the operating and maintenance costs of the systems. As capital costs drop to about $3000 US/kW, promising market opportunities appear to be developing in green power and distributed generation markets in the southwestern United States and in Europe. In this paper, we review the current status of four Dish-Stirling systems that are being developed for commercial markets and present system specifications and review system performance and cost data. We also review the economics, capital cost, operating and maintenance costs, and the emerging markets for Dish-Stirling systems.