Theoretical calculation and evaluation of n +~(240,242,244)Pu reactions

The nuclear data of n+~(240;242;244)Pu reactions for incident energy below 200 MeV are calculated and evaluated to meet the requirement in the design of an accelerator-driven subcritical system. The optical model is used to calculate the total, nonelastic, shape elastic cross sections, shape elastic scattering angular distributions, and transmission coefficients. The distorted-wave Born approximation is applied to calculate the direct inelastic scatterings to the discrete excited states. The nuclear reaction statistical models and fission theory are applied to describe neutron, proton, deuteron, triton, helium-3, alpha and c emissions, and fission consistently. The results thus obtained are compared with experimental data and the evaluated data obtained from ENDF/B-VII.1 and JENDL-4.0.     

Research on sub-surface recrystallization of single crystal nickel-based superalloy in micro-milling

Journal of Mechanical Science and Technology - The micro-structure/parts of single crystal nickel-based superalloy materials are extensively used in high temperature environments. The...     

An unsafe behaviour formation mechanism based on risk perception

It is commonly acknowledged that human behaviour is implicated in most safety problems. However, research on the formation mechanism of unsafe behaviour remains incomplete. Risk perception is one of the fundamental issues in risk research, and individual risk perception can be identified as a critical antecedent of human behaviour. This study attempts to construct and test a theoretical model to reveal the formation mechanism of unsafe behaviour based on risk perception. First, to lay a solid foundation for the developed new mechanism, several key concepts about risk perception and unsafe behaviour were explained. Second, the formation mechanism of biases in individual risk perception was developed based on psychological distance theory, and the biases in risk perception were subsequently classified. Lastly, an unsafe behaviour formation mechanism was put forward based on risk perception as an explanatory variable. This study is novel in that it uses psychological distance to explore the formation of biases in individual risk perception. Further, the presented work provides a new approach to understanding and explaining the formation mechanism of human unsafe behaviour.     

十堰市某滑坡风险分析评价

对十堰市某滑坡及其影响范围进行调查,查清滑坡变形特征和危害情况,采用定量评价方法,开展稳定性、危险性、承灾体易损性分析评价,在此基础上,进行滑坡风险分析评价,计算得到该滑坡最大财产损失为61.292万元/年,最大人口风险为1.599人/年,风险等级为极高风险,建议采取加强监测、搬迁避让或适当工程治理等方法进行风险管控,以达到防灾减灾的目的。对今后开展单体滑坡风险分析评价有一定的借鉴意义。     

鄂东南地区尾矿资源综合利用前景及开发建议思路浅析

鄂东南地区尾矿资源丰富,以往尝试过尾矿资源的利用,均未按综合利用的思路开展,导致尾矿的经济价值未充分体现,制约了尾矿资源的开发利用。通过对鄂东南尾矿资源现状分析,结合目前选冶加工技术和国家相关管理政策,提出"资源—环境—灾害"三位一体的综合利用框架和"全面摸底—资源勘查—市场调研—工艺确定—市场销售"链条化的开发利用思路,从摸清家底、市场调研、价值评估、合作开发四个方面分层次统筹推进尾矿资源的综合开发,对合理推进鄂东南地区尾矿资源的综合利用有较好的指导和借鉴意义。     

纳米技术浮选技术研究进展

本文简述了微细粒矿物资源开发利用现状、纳米技术概况和纳米捕收剂的应用。介绍了纳米技术在微细粒矿物浮选中应用发展趋势。重点介绍了纳米气泡的基本性质、纳米药剂的合成以及纳米捕收剂应用现状。研究发现纳米气泡在微细粒浮选中可以大幅度提高浮选效率,尽可能减小气泡尺寸有利于细矿粒的浮选。纳米药剂的合成存在诸多困难,乳化合成是主要的纳米粒子的合成方法。应用纳米技术合成新型浮选药剂是未来的发展方向。     

Pressureless sintering and properties of boron carbide composite materials

Boron carbide and Tantalum boride composites were prepared by pressureless sintering of B₄C with addition of TaC powder. The effect of TaC addition on the sinterability of boron carbide was studied. High densified ceramic with a relative density of 98.7% was obtained at sintering temperature of 2250°C. The composition and the microstructure of the dense composites are characterized by means of x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDX). The studies show that the composites contain boron carbide, TaB₂, and carbon phases with a homogeneous structure. In addition, the correlation between the composition and the electrical conductivity was investigated. The electrical conductivity of the composite increased with increasing addition of TaC, and a change in conduction behavior from semiconducting to metallic was observed. High hardness value of 28.49 ± 1.33 GPa was obtained by the sample with 30 wt% TaC addition.     

近似完全匹配层边界条件吸收效果分析及衰减函数的改进

完全匹配层边界条件存在两个问题，一是如何减少实际应用带来的额外存储量以及提升计算速度，另一个是如何提升匹配层的吸收效果。对于第一个问题发展了多种非分裂形式，本文采用一种直接对波场进行变换的新型非分裂方法，相比卷积完全匹配层具有不改变方程的形式以及易于实现等优势。对于如何进一步提升完全匹配层吸收效果，没有太大的进展。这是因为离散差异使匹配层的吸收问题更为复杂，一般采取增加匹配层层数的措施缩小离散差，但是又会导致计算量和存储量的增加。本文以在不增加匹配层层数以及不减小理论误差的情况下减小离散差异所带来的虚假反射为目的，分析传统的衰减因子，研究匹配层的吸收机理，设计新的衰减因子，以提高完全匹配层的吸收性能。新衰减因子能够进一步削弱虚假反射振幅，在匹配层层数为5~20层时，对应的边界反射振幅只有改进前的40%~80%。