Multi-objective aerodynamic optimization design of high-speed train head shape     

Liang Zhang  Ji-ye Zhang  Tian Li  Ya-dong Zhang 《浙江大学学报(A卷英文版)》2017,18(11):841-854

To improve the aerodynamic performance of high-speed trains (HSTs) running in the open air, a multi-objective aerodynamic optimization design method for the head shape of a HST is proposed in this paper. A parametric model of the HST was established and seven design variables of the head shape were extracted. Sample points and their exact values of optimization objectives were obtained by an optimal Latin hypercube sampling (opt. LHS) plan and computational fluid dynamic (CFD) simulations, respectively. A Kriging surrogate model was constructed based on the sample points and their optimization objectives. Taking the total aerodynamic drag force and the aerodynamic lift force of the tail coach as the optimization objectives, the multi-objective aerodynamic optimization design was performed based on a non-dominated sorting genetic algorithm-II (NSGA-II) and the Kriging model. After optimization, a series of Pareto-optimal head shapes were obtained. An optimal head shape was selected from the Pareto-optimal head shapes, and the aerodynamic performance of the HST with the optimal head shape was compared with that of the original train in conditions with and without crosswinds. Compared with the original train, the total aerodynamic drag force is reduced by 2.61% and the lift force of the tail coach is reduced by 9.90% in conditions without crosswind. Moreover, the optimal train benefits from lower fluctuations in aerodynamic loads in crosswind conditions.  相似文献   

任弼时与中华苏维埃第一次全国代表大会的召开     

廖良初 《信阳师范学院学报(哲学社会科学版)》2002,22(5):121-124

中华苏维埃第一次全国代表大会的召开和中华苏维埃共和国临时政府的成立，是我党创建人民政权的一次伟大探索和实践，它不仅对中国革命产生了深远影响，而且对新中国政权建设提供了丰富的经验。当时筹备大会的主要负责人任弼时，为大会的准备做出了重大贡献。他统一思想认识，推举毛泽东主持工作，负责人事安排，起草件，指导选举。使大会得以顺利召开。  相似文献   

招生规模核定方法评析     

梁亦菡  韩映雄 《大学.研究与评价》2007,(5)

本文对各主要规模核定方法逐一作了评述并分析其适用条件。研究发现,不存在公认完善的教育规划方法论,教育规划仍处于艺术的状态而没有成为精确科学。任何核定方法都是为一定的发展目标服务的,目标的确定及其轻重缓急的安排,反映了具体条件下招生规模对高等教育在社会经济发展过程中作用的期待。  相似文献   

城市产业模式研究     

梁玉芬 《北京城市学院学报》2003,(4):24-26

现代化的大生产从一开始就拥有一种在不断的分工中进行自身繁殖、在空间和规模上不断自我扩张 的成长机制。产业内部不断分工,在城市发展中就表现为不同类型城市产业模式。本文从五个方面阐述了不同类型 产业模式的生成原因和面临的问题。  相似文献   

A long-term experiment to investigate the relationships between high school students’ perceptions of mobile learning and peer interaction and higher-order thinking tendencies     

Gwo-Jen Hwang  Chiu-Lin Lai  Jyh-Chong Liang  Hui-Chun Chu  Chin-Chung Tsai 《Educational technology research and development : ETR & D》2018,66(1):75-93

In this study, a one-year program was conducted to investigate the relationships between students’ perceptions of mobile learning and their tendencies of peer interaction and higher-order thinking in issue-based mobile learning activities. To achieve the research objective, a survey consisting of eight scales, namely, usability, continuity, adaptive content, collaboration, communication, problem-solving, critical thinking and creativity, was developed. A total of 658 students from 38 high schools in Taiwan filled in the questionnaire after experiencing issue-based mobile learning activities. From the exploratory and confirmatory factor analyses, it was found that the questionnaire had high reliability and validity. The structural equation model further revealed that the provision of adaptive content in the mobile learning had positive impacts on the students’ tendency to interact with peers (i.e., collaboration and communication), which further affected their tendency to engage in higher-order thinking (i.e., problem-solving, critical thinking, and creativity). The findings of this study provide a good reference for researchers and school teachers who intend to promote mobile learning in school settings.  相似文献   

法律保护、控股股东与公司绩效分析     

袁梁 《渭南师范学院学报》2011,(9):87-89

我国上市公司具有典型的股权集中特征,研究控股股东行为对于改善我国公司治理具有重要意义。控制权收益是控股股东最大化自身利益的载体。现实决策中,控股股东往往需要权衡公共收益和私人收益哪一个更有利于实现自身利益最大化。文章从法律保护角度出发,以控制权收益为切入点,构建了一个研究控股股东行为的分析框架。结合我国控股股东的实际情况,将该框架进一步具体化,用来解释我国国有控股公司与民营控股公司的绩效差异之谜。  相似文献   

宗教文化对大学校园文化的影响及对策     

程钢  梁馨予 《湖南广播电视大学学报》2011,(1):89-92

大学校园文化对大学生理想信念的形成和心理健康的发展都具有重要作用.而近年来宗教文化对校园文化的影响越来越大,对学生的人生观、价值观产生了不容忽视的影响.本文通过调查研究,分析了大学生信仰宗教的基本情况、原因、传播特点和影响,提出了应对大学生信仰宗教现象的对策.  相似文献   

农村教师培训需求对高师课程与教学改革的启示     

梁萍云 《继续教育研究》2011,(1):90-92

高等师范院校课程与教学改革要与基础教育课程改革相适应,教师培训需求是教师对基础教育课程改革的心理反映。对农村教师培训需求的调查发现,高师课程与教学改革应该完善教育专业课程体系建设,增加教师技能训练课程门类;加强教育专业课程内容改革,突显课程内容的时代性和实用性;转变学习方式,突出学生主体性教学;关注学习过程,注重形成性评价。  相似文献   

基于远程学习者个体需求的教学策略探究   总被引：1，自引：1，他引：0  

梁九义 《中国远程教育(综合版)》2011,(2)

远程教学是建立在信息技术和学习者学习需求基础上的教学,在具体的教学过程中采用什么样的教学策略,不仅要看技术条件和学科特点,更重要的是要看学习者的实际需求。本文在分析了远程学习者特征和学习需求的基础上,着力探讨了网络环境下基于学习者个体需求的教学策略。在宏观上提出了三种比较可行的教学策略,即资源性教学策略、非系统性教学策略和服务性教学策略。  相似文献   

“自愿问责制”:美国高等教育问责制发展的新动向     

柳亮 《比较教育研究》2011,(2):81-85

近年来,"自愿问责制"(VSA)的兴起为美国公立学院和大学改革注入了新的活力,反映了美国公立院校领导层应对新挑战的基本思考。"大学肖像"模板是"自愿问责制"的主要实现形式,包含学生与家庭信息、学生经历与体会以及学生学习结果三个截面的内容,体现了整合性与集约化并举、规范化与弹性结合、创造性与渐进性兼顾等特点。虽然"自愿问责制"的发展伴随着质疑且存在一些有待解决的难题,但其发展对美国高等教育产生了重要影响。  相似文献