Simplex stochastic collocation with ENO-type stencil selection for robust uncertainty quantification

Multi-element uncertainty quantification approaches can robustly resolve the high sensitivities caused by discontinuities in parametric space by reducing the polynomial degree locally to a piecewise linear approximation. It is important to extend the higher degree interpolation in the smooth regions up to a thin layer of linear elements that contain the discontinuity to maintain a highly accurate solution. This is achieved here by introducing Essentially Non-Oscillatory (ENO) type stencil selection into the Simplex Stochastic Collocation (SSC) method. For each simplex in the discretization of the parametric space, the stencil with the highest polynomial degree is selected from the set of candidate stencils to construct the local response surface approximation. The application of the resulting SSC–ENO method to a discontinuous test function shows a sharper resolution of the jumps and a higher order approximation of the percentiles near the singularity. SSC–ENO is also applied to a chemical model problem and a shock tube problem to study the impact of uncertainty both on the formation of discontinuities in time and on the location of discontinuities in space

The 30 doradus molecular cloud at 0.4 pc resolution with the atacama large millimeter/submillimeter array: physical properties and the boundedness of CO-emitting structures

Large scale structure and cosmolog

PRELIMINARY HAZARD SUMMARY REPORT ON THE BOILING EXPERIMENTAL REACTOR (BER)

A preliminary evaluation of the hazards associated with a 20-Mw boiling reactor for the purpose of determining site requirements is presented. The Boiling Experimental Reactor design, safety features, and performance are given and the surroundings of the site at Argonne National Laboratory are described. (T.R.H.

HAZARD SUMMARY REPORT ON THE EXPERIMENTAL BOILING WATER REACTOR (EBWR)

In addition to the nine cross-shaped control rods which pass through vertical guide channels in the core, a secondary noninherent safety mechanism in the form of a pressurized concentrated boric acid solution can reduce the reactivity by at least 12.5% k in about 20 seconds. With regard to inherent safety, the EBWR has a much stronger metal temperature coefficient, but a considerably weaker steam formation shutdown mechanlsm, than the Borax reactors. Estimates were made of the amount of reactivity which can be controlled by steam formation in the EBWR. The maximum heat flux in EBWR is believed to be below the burnout point by at least a factor of 4 to 5, based on laboratory tests with electrically heated plates. The EBWR is surrounded by a gas-tight steel building having a volume of abput 400,000 ft/sup 3/ and designed to withstand an internal pressure of 15 psig. A 15,000-gal reservoir of water is suspended from the dome of the building for emergency cooling. The gas-tight building could easily withstand the internal pressure resulting from blowdown of the pressurized water in the reactor. The major design and operating features of the EBWR facility are summarized. (M.H.R.