19 research outputs found
Solvent Extraction Studies of Gadolinium in Tri-Butyl Phosphate
AbstractFast reactor spent fuel reprocessing plants should be designed for inherent criticality safety due to high plutonium content. Addition of soluble neutron poison is one way to do that. Gadolinium is the best choice based on neutron absorption cross section and chemical compatibility. In this work, using classical thermodynamic approach, the distribution coefficient of gadolinium in tributyl phosphate has been calculated and compared with the experimental data. The influence of acidity and uranium at equilibrium on gadolinium distribution in tributyl phosphate has been investigated. The result establishes the feasibility of employing gadolinium as soluble neutron poison in fast fuel reprocessing
Distributed Block Coordinate Descent for Minimizing Partially Separable Functions
In this work we propose a distributed randomized block coordinate descent
method for minimizing a convex function with a huge number of
variables/coordinates. We analyze its complexity under the assumption that the
smooth part of the objective function is partially block separable, and show
that the degree of separability directly influences the complexity. This
extends the results in [Richtarik, Takac: Parallel coordinate descent methods
for big data optimization] to a distributed environment. We first show that
partially block separable functions admit an expected separable
overapproximation (ESO) with respect to a distributed sampling, compute the ESO
parameters, and then specialize complexity results from recent literature that
hold under the generic ESO assumption. We describe several approaches to
distribution and synchronization of the computation across a cluster of
multi-core computers and provide promising computational results.Comment: in Recent Developments in Numerical Analysis and Optimization, 201