为能够在合理计算规模下准确模拟空爆自由场冲击波特征的网格划分方案,获得可靠的计算结果,本文运用验证与确认(verification and validation,V&V)方法,通过开展网格敏感性分析,确认了炸药空爆计算模型的数值解、外推估值、网格收...为能够在合理计算规模下准确模拟空爆自由场冲击波特征的网格划分方案,获得可靠的计算结果,本文运用验证与确认(verification and validation,V&V)方法,通过开展网格敏感性分析,确认了炸药空爆计算模型的数值解、外推估值、网格收敛指标与比例距离的定量关系,给出了满足不同网格收敛指标要求的最大比例网格尺寸随比例距离位置的变化关系。据此,在比例距离Z为0~40 m·kg^(-1/3)范围内,给出了划分渐变网格的优化方案。针对1维、2维、3维计算模型,分别比较了细网格、粗网格、渐变网格方案的计算精度与计算耗时情况,讨论了本文提出网格划分方法的适用性。同时,采用本文建议的网格优化方案,给出了动爆冲击波毁伤飞机数值模拟场景的应用算例。结果表明,本文建议的网格优化方案可在几乎不降低计算精度的前提下显著提升计算效率,可为空爆自由场或者近似计算场景的数值模型网格划分提供参考。展开更多
“自我概念”这一定义自William James提出以来,一直备受国内外学者的关注,特别是近年来,自我概念作为情感因素,对二语习得结果发挥着至关重要的作用,研究表明积极的自我概念有利于学习者的英语学习。在英语学习中还有一个比较常见的情...“自我概念”这一定义自William James提出以来,一直备受国内外学者的关注,特别是近年来,自我概念作为情感因素,对二语习得结果发挥着至关重要的作用,研究表明积极的自我概念有利于学习者的英语学习。在英语学习中还有一个比较常见的情感因素“焦虑”,它一直被认为对英语学习起着消极的作用。本研究旨在探究大学生英语口语自我概念与课堂口语焦虑的情况,并对其进行相关性研究,以此为中国高校英语口语教学提供一定借鉴意义。本研究采用调查问卷法与访谈调研法研究分析了重庆大学229名大三学生英语口语概念与课堂口语焦虑的关系,并得出以下结论:1) 大学生英语口语自我概念水平总体上偏低,而课堂口语焦虑状况普遍存在,大多数学生在英语课堂上经历口语焦虑;2) 大学生的英语口语自我概念与课堂口语焦虑之间整体上是负相关关系;3) 男女生、文理科学生的英语口语自我概念和课堂口语焦虑存在差异;4) 英语口语自我概念可以很好地预测课堂口语焦虑。The definition of “self-concept” has attracted much attention from scholars both at home and abroad since it was proposed by William James. Especially in recent years, self-concept, as an affective factor, plays a crucial role in the outcome of second language acquisition, and studies have shown that positive self-concept is beneficial to learners’ English learning. There is another common affective factor “anxiety” in English learning, which has been considered to play a negative role in English learning. The present study aims to investigate college students’ English speaking self-concept and English classroom speaking anxiety, and to conduct a correlation study, so as to provide some reference for the teaching of English speaking in Chinese universities. This study used questionnaire and interview research methods to study and analyze the relationship between English speaking concept and English classroom speaking anxiety of 229 juniors in Chongqing University, and came to the following conclusions: 1) College students’ English speaking self-concept levels are generally low, while English classroom speaking anxiety is common, and most students experience speaking anxiety in the English classroom;2) There is a negative correlation between college students’ English speaking self-concept and English classroom speaking anxiety;3) There are differences between male and female students, and students of arts and sciences in their English speaking self-concept and English classroom speaking anxiety;4) English speaking self-concept can be a good predictor of classroom speaking anxiety.展开更多
文摘为能够在合理计算规模下准确模拟空爆自由场冲击波特征的网格划分方案,获得可靠的计算结果,本文运用验证与确认(verification and validation,V&V)方法,通过开展网格敏感性分析,确认了炸药空爆计算模型的数值解、外推估值、网格收敛指标与比例距离的定量关系,给出了满足不同网格收敛指标要求的最大比例网格尺寸随比例距离位置的变化关系。据此,在比例距离Z为0~40 m·kg^(-1/3)范围内,给出了划分渐变网格的优化方案。针对1维、2维、3维计算模型,分别比较了细网格、粗网格、渐变网格方案的计算精度与计算耗时情况,讨论了本文提出网格划分方法的适用性。同时,采用本文建议的网格优化方案,给出了动爆冲击波毁伤飞机数值模拟场景的应用算例。结果表明,本文建议的网格优化方案可在几乎不降低计算精度的前提下显著提升计算效率,可为空爆自由场或者近似计算场景的数值模型网格划分提供参考。
文摘“自我概念”这一定义自William James提出以来,一直备受国内外学者的关注,特别是近年来,自我概念作为情感因素,对二语习得结果发挥着至关重要的作用,研究表明积极的自我概念有利于学习者的英语学习。在英语学习中还有一个比较常见的情感因素“焦虑”,它一直被认为对英语学习起着消极的作用。本研究旨在探究大学生英语口语自我概念与课堂口语焦虑的情况,并对其进行相关性研究,以此为中国高校英语口语教学提供一定借鉴意义。本研究采用调查问卷法与访谈调研法研究分析了重庆大学229名大三学生英语口语概念与课堂口语焦虑的关系,并得出以下结论:1) 大学生英语口语自我概念水平总体上偏低,而课堂口语焦虑状况普遍存在,大多数学生在英语课堂上经历口语焦虑;2) 大学生的英语口语自我概念与课堂口语焦虑之间整体上是负相关关系;3) 男女生、文理科学生的英语口语自我概念和课堂口语焦虑存在差异;4) 英语口语自我概念可以很好地预测课堂口语焦虑。The definition of “self-concept” has attracted much attention from scholars both at home and abroad since it was proposed by William James. Especially in recent years, self-concept, as an affective factor, plays a crucial role in the outcome of second language acquisition, and studies have shown that positive self-concept is beneficial to learners’ English learning. There is another common affective factor “anxiety” in English learning, which has been considered to play a negative role in English learning. The present study aims to investigate college students’ English speaking self-concept and English classroom speaking anxiety, and to conduct a correlation study, so as to provide some reference for the teaching of English speaking in Chinese universities. This study used questionnaire and interview research methods to study and analyze the relationship between English speaking concept and English classroom speaking anxiety of 229 juniors in Chongqing University, and came to the following conclusions: 1) College students’ English speaking self-concept levels are generally low, while English classroom speaking anxiety is common, and most students experience speaking anxiety in the English classroom;2) There is a negative correlation between college students’ English speaking self-concept and English classroom speaking anxiety;3) There are differences between male and female students, and students of arts and sciences in their English speaking self-concept and English classroom speaking anxiety;4) English speaking self-concept can be a good predictor of classroom speaking anxiety.
