Unsteady simulation for a high-speed train entering a tunnel

In order to study the unsteady aerodynamics effects in railway tunnels, the 3D Reynolds average Navier-Stokes equations of a viscous compressible fluid are solved, and the two-equation k-? model is used in the simulation of turbulence, while the dynamic grid technique is employed for moving bodies. We focus on obtaining the changing tendencies of the aerodynamic force of the train and the aerodynamic pressures on the tunnel wall and train surface, and discovering the relationship between the velocity of the train and the intensity of the micro pressure wave at the tunnel exit. It is shown that the amplitudes of the pressure changes in the tunnel and on the train surface are both approximately proportional to the square of the train speed, so are the microwave and the drag of the train.     

Aln(n=2～22)团簇构型研究

为计算Aln(n=2～22)团簇构型和能量变化,依据量子化学方法,应用Gaussian 03程序中密度泛函理论(DFT)的B3LYP方法6～31 G基组对Aln(n=2～22)团簇构型和能量变化进行最基本的理论研究.通过改变Aln(n=2～22)团簇中Al原子数n的值,分别在相同的理想条件下计算,求得Aln(n=2～22)团簇的稳定构型、结合能、HOMO-LUMO能隙和平均键长.利用Gaussian 03的输出结果,将实验结果与参考数据进行比较,归纳总结Aln(n=2～22)团簇稳定构型、结合能及平均键长的变化规律.     

“单独二孩”政策下我国受教育人口变化趋势研究

基于中国2005年1%人口抽样和2010年人口普查资料,在对不同夫妇的婚配概率和堆积释放生育估计的基础上,从全国、城镇、农村三个维度,对学龄前、小学、初中、高中、大学五个阶段的受教育人口变动趋势进行预测和分析。在"单独二孩"政策下,我国受教育人口的规模有所增长,但长期总趋势是在波动中下降;学龄前儿童在2017年达到峰值,小学、初中、高中、大学学龄人口经过不同的波动轨迹在2020—2036年间逐类达到高峰后转为下降;城镇在波动中增长,农村则单边下降;全国受教育人口的变动态势,主要受城镇受教育人口变动的影响;要特别关注城乡学龄人口的不同发展态势,为应对未来各级学龄人口变动预先做好充分准备;"十三五"时期城镇学龄前儿童的快速增长,是制定"十三五"教育发展规划必须正视和解决的问题。     

基于Proteus的DSP虚拟实验系统设计与开发

针对传统DSP实验受实验场所、实验设备、实验学时制约的问题,基于Proteus设计和开发了DSP虚拟实验系统,给出了系统总体设计方案、开发流程和应用示例。该系统具有高效、开放、灵活、经济、易维护等优点,可辅助实物实验,帮助学生掌握DSP原理与应用系统设计方法,提高工程实践能力与科技创新能力。     

关于柯西方程的一点注记

若函数f在一点连续,则柯西方程的解是唯一的.在此假设下,要求函数f的一部分点满足柯西方程,证明了解的唯一性,并推广已知的结论.     

研究生层次化学习能力影响因素分析及对策研究

通过借鉴国内外关于学习能力的研究成果,提出了研究生三维度（自主学习能力、科研能力和创新能力）层次化学习能力体系,通过问卷调查收集数据,综合运用聚类分析和粗糙集理论,提取了影响研究生学习能力的关键因素和规则,并进行了层次化能力一致性分析,最后给出了提升研究生学习能力的对策。     

湖北民族地区高校英语教育专业定位探析

根据湖北民族地区英语教育专业办学定位和学生实际情况,本文对该地区英语教育专业的专业目标定位以及课程设置展开分析和探讨,旨在抛砖引玉,为该地区高校英语教育专业课程体系改革问题提供一些有益的思考和借鉴。     

Extraterrestrial artificial photosynthetic materials for in-situ resource utilization

Aerospace milestones in human history, including returning to the moon and manned Martian missions, have been implemented in recent years. Space exploration has become one of the global common goals, and to ensure the survival and development of human beings in the extraterrestrial extreme environment has been becoming the basic ability and technology of manned space exploration. For the purpose of fulfilling the goal of extraterrestrial survival, researchers in Nanjing University and the China Academy of Space Technology proposed extraterrestrial artificial photosynthesis (EAP) technology. By simulating the natural photosynthesis of green plants on the Earth, EAP converts CO₂/H₂O into fuel and O₂ in an in-situ, accelerated and controllable manner by using waste CO₂ in the confined space of spacecraft, or abundant CO₂ resources in extraterrestrial celestial environments, e.g. Mars. Thus, the material loading of manned spacecraft can be greatly reduced to support affordable and sustainable deep space exploration. In this paper, EAP technology is compared with existing methods of converting CO₂/H₂O into fuel and O₂ in the aerospace field, especially the Sabatier method and Bosch reduction method. The research progress of possible EAP materials for in-situ utilization of extraterrestrial resources are also discussed in depth. Finally, this review lists the challenges that the EAP process may encounter, which need to be focused on for future implementation and application. We expect to deepen the understanding of artificial photosynthetic materials and technologies, and aim to strongly support the development of manned spaceflight.     

体育院校实验班英语教学的创新研究

本文在基于对体育院校实验班群体特征以及影响该群体英语水平提高因素分析的基础上,主要从教学理念、教学模式、课程设置与教材选择、教学内容与教学手段、评估体系等五个方面阐述体育院校实验班英语教学的创新。     

物理化学教学过程中的改革与探索

物理化学课是高等学校材料类专业重要的学科基础课。本文通过对物理化学课程的教学内容、教学方法、教学思想和实验教学等方面进行改革与探索,从而激发学生学习的积极性和主动性,更有效地提高物理化学课程的授课质量。