Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

An optimal reconstruction of the neutronic activity field can be determined for a nuclear reactor core using a data assimilation framework to merge information from models and measurements. In this paper, we focus on solving the inverse problem of determining an optimal repartition of the measuring instruments within the core, to get the best possible results from the data assimilation reconstruction procedure. The position optimisation is realised using a Simulated Annealing algorithm, based on the Metropolis-Hastings proposition. Moreover, algebraic improvements of data assimilation have been developed, optimising their computational performance, and are presented here.     

甘肃工业项目现状、问题与对策分析

本文在对甘肃省工业项目的总体情况进行分析的基础上,对全省工业发展过程中,项目工作存在的主要问题进行了探讨,从项目应把握的基本原则、关系、重点工作、服务意识、推进机制等方面提出了一些加快推动项目的思路和措施。     

Anisotropic elasto-plastic solutions for cavity expansion problem in saturated soil mass

On the basis of the yield criterion of Matsuoka and Nakai (1974), novel elasto-plastic solutions are obtained for the cavity expansion problem in an anisotropic medium. The solutions are formulated by employing a small-strain analysis in an elastic zone and a large-strain analysis in a plastic zone around the cavity in a soil mass. In light of the initial condition, the plastic radius and the stress in the plastic zone are derived by incorporating the large-strain analysis, the influence of stress anisotropy (K0) and the non-associated flow rule, and two fundamental solutions for the cavity expansion problem under undrained and drained conditions are presented in an anisotropic soil mass. Finally, a comparison with the previous results is performed for verification.     

Some iterative algorithms for the obstacle problems

In this paper we propose some iterative algorithms for the obstacle problems discretized by the finite difference method. We rewrite the obstacle problem to an equivalent complementarity problem. We use the regularization trick to non-smooth absolute function. Then we apply the Newton's method to obtain an iterative algorithm. Some other two algorithms based on this algorithm are derived. Numerical experiments show the effective of the algorithm.     

Calderon's preconditioning for periodic fast multipole method for elastodynamics in 3D

Preconditioning methods based on Calderon's formulae for the periodic fast multipole method for elastodynamics in 3D are investigated. Three different types of formulations are proposed. The first type is a preconditioning just by appropriately ordering the coefficient matrix without multiplying preconditioners. The other two types utilise preconditioners constructed using matrices needed in the main fast multipole method algorithms. We make several numerical experiments with proposed preconditioners to confirm the efficiency of these proposed methods. We also conclude that the preconditioning of the first type is faster with respect to the computational time than other preconditioning methods discussed in this article. Copyright © 2012 John Wiley & Sons, Ltd.     

我国城市地理研究的学术规范问题

改革开放以来,我国大陆包括城市地理研究在内的城市研究取得了长足的进展,但在城市研究的学术规范方面也存在明显的不足。这种不足具体表现在问题意识不足、学术对话严重不足、引用不太规范、学术史意识不强及理论创新不够。只有正视这些问题,认真分析成因和思考对策,才有可能在已有成绩的基础上找准方向,重新出发,并找到通向世界学术的"桥梁"。本文对此作了尝试。     

B-spline method for solving Bratu's problem

In this paper, we propose a B-spline method for solving the one-dimensional Bratu's problem. The numerical approximations to the exact solution are computed and then compared with other existing methods. The effectiveness and accuracy of the B-spline method is verified for different values of the parameter, below its critical value, where two solutions occur.     

Analytic Function Expansion Nodal (AFEN) Method in Hexagonal-Z Three-Dimensional Geometry for Neutron Diffusion Calculation

The analytic function expansion nodal (AFEN) method in hexagonal-z geometry is described focusing on its unique features, including the use of node-interface flux moments. Multigroup extension based on matrix function theory and coarse group rebalance (CGR) acceleration are also described. The COREDAX code implementing the AFEN method is verified testing on the VVER-440 benchmark problem, a “simplified” VVER-1000 benchmark problem, and the SNR-300 benchmark problem.