正电子冲击下氦电离三重微分截面的理论计算

我们发展了一种正电子碰撞原子电离的畸变波Born近似方法， 在这个方法中，正负电子偶素通道通过一个ab initio的光学势附加到入射粒子和靶的相互作用势上，且通道对电离作用被第一次被考虑在正电子碰撞原子电离的过程中. 应用这个方法计算了在50 eV入射能量范围氦的电离的三重微分截面，计算结果和实验数据很好的符合.     

以提升创新能力为目标的基础力学实践教学初探

创新型基础力学人才的培养既要注重专业知识的学习,又要重视学生思辨、质疑与应用能力的提升。受限于不断削减的学时,传统基础力学课程仍以讲授为主,难以开展有效的实践教学环节。这种重理论轻实践的模式易导致学生学习兴趣下降、综合能力不足。为弥补实践短板,国内高校正逐步开展各类型大学生实践项目。本文以大学生创新训练项目为例,系统介绍项目实施期间教师有效的引导方式,以期为新时期力学人才培养贡献力量。     

用单颗粒气溶胶质谱研究海宁市秋、冬季PM_(2.5)化学组成及来源

对海宁市区PM_(2.5)来源进行分析,分别于2016年11月11日~24日以及2016年12月13日~21日期间,使用单颗粒气溶胶质谱仪(SPAMS)在海宁市环境保护监测站点位进行了为期14天和8天的定点监测,分别代表了秋季和冬季的监测结果。结果表明,监测期间海宁市总体空气质量较好,优、良天气占比为75.8%。海宁市首要污染物为机动车尾气源,燃煤源次之,工业源排在第三位。整体来看,监测期间PM_(2.5)质量浓度的升高大多伴随着燃煤及机动车尾气占比的同步升高。秋、冬季的重度污染过程与燃煤源和机动车尾气源的升高有关,其中秋季的燃煤源贡献高峰可能与监测点位西北方向的气团传输有关。     

甲烷的池核沸腾传热实验研究

本文对饱和液体甲烷在0.12MPa下的池内核态沸腾传热进行了系统的实验研究,获得了相应的沸腾传热数据.对实验数据进行了详细的不确定度分析;将实验结果与现有的池核沸腾传热系数关联式进行比对,并在原有的关联式基础上进行改进,得到了适合甲烷的池核沸腾传热系数关联式.     

Plasma-screening effects on positronium formation

Plasma-screening effects on positronium(Ps) formation for positron-hydrogen collisions in a Debye plasma environment is further investigated using the screening approximation model with the inclusion of the modified structure of Ps.More accurate Ps formation cross sections(n = 1, 2) are obtained for various Debye lengths from the Ps formation thresholds to 50 eV. The influence of considering modified bound-state wave functions and eigenenergies for the Ps is found to result in the reduction of the Ps formation cross sections at low energies, whereas it cannot counteract the enhancement of the Ps formation by the Debye screening.     

Unnatural parity resonance states in positron-excited hydrogen scattering

<正>The coupled-channels optical method for positron scattering has been applied to investigate resonance states with unnatural parities in a positron-excited hydrogen system.The positronium formation channels and continuum channel are included via a complex equivalent local potential.Resonance states with angular momenta L = 1 to L = 2 and parities（—1）^L+1 are calculated.Resonance energies and widths are reported and compared with other theoretical calculations.We found that the opening positronium formation channels play an important role in forming nondipole Feshbach resonances.     

功能性近红外光谱系统及锁相放大器算法的研究

功能性近红外光谱(functional near-infrared spectroscopy, fNIRS)技术是一种新兴的非侵入式光学技术,该技术可以测量脑皮层的功能性活动信息。介绍了单通道fNIRS系统的开发,为了验证系统的性能,2人参与了算数运算任务,获得了氧合血红蛋白和脱氧血红蛋白的浓度变化。锁相放大器在fNIRS系统中可以很好地提取淹没在噪声中微弱的光强信号,但是模拟锁相放大器价格昂贵,对多通道系统来说是很大的负担。设计了数字锁相放大器算法,通过与模拟锁相进行比较,结果表明设计的数字锁相放大器可以取代价格昂贵的模拟锁相放大器。     

Triple-differential cross section for single ionization of H2 by electron impact

The triple-differential cross section (TDCS) for the (e,2e) ionization of a hydrogen molecule is calculated using the molecule distorted-wave Born approximation (MDWBA). Distorted waves are obtained by solving momentum-space coupled-channel Lippmann-Schwinger equations, including the ground state and the lowest-lying electronic state of b3Σu . TDCSs at the incident energy 100 eV in coplanar asymmetric geometry are reported. The present calculations are compared with the available experimental measurements and the theoretical results.     

Coupled-Channels Optical Calculation for Electron Scattering from Metastable Helium

Coupled-channels optical calculations for total and resonance excitation integral cross sections for electron scattering on the metastable level 2^1,3S of helium are presented. The results are in agreement with other theoretical and experimental data.     

基于化学学科能力的高三教学评一体化设计*

基于“化学学科能力内涵构成及其活动表现模型”,分析北京市近3年高考试题,总结北京高考对学生的要求;设计了高三三阶段复习计划,并以第一阶段复习为例,展示大单元复习教学整体设计、高三统练整体规划和试题设计;分析统练中学生各能力要素和知识主题的得分率,形成针对年级的评价、针对教学班教师的评价、针对个体学生的个性化评价。