Quasielastic Scattering of the Halo Nucleus ^6He at 25 MeV／u from a ^9Be Target

The differential cross sections of quasielastic scattering of a 25 MeV/u ^6He from ^9Be target have been measured.The double-folding model approach is applied to generate the real part of the optical potential. The imaginary potential parameters as well as some of the real potential parameters are studied in comparison with the experimental data. The effect of the unstable nucleus is discussed.     

Measurement of the Breakup Cross Sections in ^6He＋^9Be Reaction at 25 MeV／Nucleon

The breakup reaction cross sections were measured for the reaction of^6He at 25 MeV/nucleon from ^9Be target with intensity of 10^5 pps. By fitting the energy spectra of breakup α particles with Gaussian functions, the angular distribution of differential cross sections in the laboratory system has been extracted and compared with the Serber model calculations. The good agreement between the calculation and the experimental data favours a dominant configuration of the ^4He core plus valence neutrons for the structure of^6He.     

共享平台下供应链闲置资源动态优化配置策略

随着共享经济的发展,其领域已从消费环节延伸到供应链层面。供应链上闲置资源如何重新配置,以实现共享,提高资源利用率,是共享供应链企业面临的新问题。本文考虑基于共享平台的供应链闲置资源匹配过程的动态性,利用微分博弈和动态规划原理分别建立集中式决策下、无成本分担和有成本分担契约的分散式决策下共享供应链闲置资源的优化配置模型,并构建对应的哈密顿-雅克比-贝尔曼(HJB)方程,求解和分析三种情形下资源供应方、共享平台和需求方关于供应链共享闲置资源的最优配置策略。结果表明,成本分担契约在一定条件下可提高供应链闲置资源参与方的积极性,并使供应链上各参与方利润增加,实现共享供应链的Pareto改进。     

水蕨(Ceratopteris thalicroides)种群的分布格局

对国家二级重点保护野生植物水蕨(C．thalicroides)部分分布区进行了野外调查，共发现13个野生水蕨种群．水蕨种群的生境主要为海拔低于1000m的水稻田．各种群分布面积较小，种群内植株数和密度相差很大．采用方差／均值比率、t值检验、负二项参数、扩散型指数、Cassic指标、丛生指标、平均拥挤度和聚块性指标等方法，研究了种群内植株数大于50株的10个野生水蕨种群的分布格局，并运用邻接格子样方法进行了格局规模检验，结果表明水蕨种群分布格局类型为聚集分布型，但各种群聚集分布强度不同．水蕨孢子及无性繁殖体近距离传播是造成其聚集分布的主要原因．人为因素的作用导致水蕨种群的灭绝．