列车荷载对下穿盾构隧道影响的模型试验

为研究地面线路运营对下穿盾构隧道结构的影响规律,基于相似比理论建立室内大型试验模型,模拟上部列车荷载作用下土层及其内部盾构隧道结构的受力变形过程,总结变形规律。结果表明,模型试验能够较好地反映外部荷载影响下土层以及内部盾构隧道结构的受力和变形特性;地表列车荷载在土层传递过程中,同一层面上沿地面线路方向的土压力大于两侧土压力,远离线路的地层受列车荷载影响相对较小,同一竖向截面土压力变化量由上至下逐渐减小,即外部荷载对浅层土的影响明显大于深层土;盾构隧道在地表列车行驶过程中,环向出现背车面受拉迎车面受压的受力特性,呈斜向压扁,纵向应变从中间交叉点向盾构隧道两侧逐渐减小,呈下凹压弯;盾构隧道埋深越小,受地表荷载影响越显著,增大一倍埋深对应纵向应变最大值减小约44.5%。     

Students' reasoning about chemical bonding: The lacuna of repulsion

This article concerns a lacuna in chemistry students' reasoning about chemical bonding. Although chemistry students are familiar with the charges that make up the atom––both positive and negative––they refer only to the attraction between unlike charges. Specifically, they ignore the repulsion between the positive nuclei. We named this disregard of repulsion the lacuna of repulsion. Repulsion is a crucial component in the force-based explanation of chemical bonding, presenting the bond as a dynamic equilibrium between attraction and repulsion electrical forces. We noticed this lacuna incidentally while interviewing chemistry students for a bigger project aimed at supporting students in understanding the force-based explanation of chemical bonding. This article describes our systematic qualitative study of the lacuna of repulsion and its impact on mental models of 23 high school chemistry students. Our findings show that students use six mental models, most of them built upon each other. Beginning from a simple mental model that describes the chemical bond as electrons, continuing with the including attraction forces, and completing with repulsion and a dynamic view of the bond. Only when one considers both attraction and repulsion forces and understands the dynamic balance between them is it possible to build the force-based dynamic mental model of chemical bonding.     

混合式教学模式在高职《外贸口语》教学中的应用研究

将混合式教学模式应用于高职《外贸口语》教学中,可以极大提高学生学习积极性和参与度,可以更加有效地培养学生在外贸工作中的沟通能力。通过展示“价格谈判”内容,阐述混合式教学在课前探索、课中导学和课后拓展环节的应用,以期为外贸行业培养更多合格的技能型人才。     

The Role of Students’ Personality Characteristics, Self-Perceived Competence and Learning Conceptions in the Acquisition and Development of Social Communicative Competence: A Longitudinal Study

An important purpose of higher social work education is to guide students to acquire and develop social-communicative competencies. The purpose of this study was to investigate the role students’ personality characteristics, self-perceived communicative competence and learning conceptions play in the acquisition and development of social-communicative competencies. We designed and tested a hypothetical model on the student-related variables – self-perceived communicative competence, learning conceptions and reported learning activities regarding communication – in relation to performance scores. We were interested in developmental trends in the above mentioned variables. We also wanted to gain insight into the relationships among the variables. The study was set up according to a longitudinal, within-subjects design in order to study intra-individual changes. One-hundred and twenty-three first-year social-work students participated in this study. Many changes were found in students characteristics, reported deployed learning activities and study results during their first academic year. Except for confidence in “showing sympathy”, which was already relatively high at the beginning of the study, all scores on aspects of students’ self-perceived social-communicative competence increased. Assessment scores on comparable communication tests also increased significantly. Extraversion and emotional stability were the only two personality characteristics, which seemed rather stable. Agreeableness decreased while autonomy increased continuously during the first academic year. It seemed to be possible to set up a model, which may serve as a starting point for further research into the development of social-communicative competence.     

Fuel Burning Rate Model for Stratified Charge Engine

A zero-dimensional single-zone double-curve model is presented to predict fuel burning rate in stratified charge engines, and it is integrated with GT-Power to predict the overall performance of the stratified charge engines. The model consists of two exponential functions for calculating the fuel burning rate in different charge zones. The model factors are determined by a non-linear curve fitting technique, based on the experimental data obtained from 30 cases in middle and low loads. The results show good agreement between the measured and calculated cylinder pressures, and the deviation between calculated and measured cylinder pressures is less than 5%. The zero-dimensional single-zone double-curve model is successful in the combustion modeling for stratified charge engines.     

李鸿章与淮系集团研究的新视野

李鸿章和淮系集团一直备受学术界关注,但研究视野多集中于革命和近代化视野。若从更为宏观的角度,借鉴管理学的某些方法来看待二者之间的关系,李鸿章领导的淮系集团已具备现代企业的雏形。     

人口流动模式中隐含的农民增收路径及政策含义

人口流动模式的核心思想是表达二元经济发展模式中人口流动的意义,从中挖掘如何促使农民增收的思想似乎有些牵强。但因发展中国家“惟工业化”的实践不尽人意而滋生了农民增收问题之后,这种挖掘既是对已有工业化实践的一种检讨,又是对现有农民增收政策实践的一种理论解释。研究表明,刘易斯模式、拉尼斯一费模式隐含了“迂回”的路径工业化,而托达罗模式表达了直接的路径大力发展农业经济。目前,这些模式隐含或直接表达的农民增收路径具有重要的政策含义。     

地效飞行器动力增升系统安装位置的实验研究

本文通过模型实验研究了动力增升系统的安装位置对典型地效飞行器静态推力恢复和静态升力的影响,进而研究了改变动力增升系统的安装位置后,飞行器起飞距离、起飞速度和升力系数的变化,并探讨了主翼端板对上述实验结果的影响。实验结果证明,设计合理的动力增升系统能够在保持地效飞行器纵向稳定性的同时能有效改善起飞性能。     

基于“四位一体”的“双基”英语口语教学模式

随着大学英语教学改革的不断深入,如何培养学生英语口语表达和交际能力在教学中处于特别重要的地位。分析目前大学英语口语教学中存在的问题,结合包天仁教授提出的"四位一体"教学法,论述以提高英语交际能力为目的的基于"四位一体"的"双基"口语教学模式。     

职业教育“工匠精神”培养初探

自李克强总理在《政府工作报告》中提出"培育精益求精的工匠精神",这为职业院校人才培养指明了方向。每年职业院校作为高素质技能型人才培养的一个重要阵地,源源不断地为国家经济的发展输送各类技能人才,因此要把"工匠精神"的培养融入实习实训的课程中,这样才能培育大批具有专业技能与工匠精神,适应社会需要的高素质劳动者和技能人才。