具有复介电常量对称结构一维三元光子晶体透射谱的研究

利用传输矩阵法理论,研究含复介电常量对称结构一维三元光子晶体的光传输特性。结果表明:当各层介质的介电常量均为实数时,在较宽的禁带范围内出现一条透射率为100%的透射峰;当介质介电常量含正虚部时,禁带中的透射峰出现透射衰减现象,若含有负虚部时,透射峰则出现透射增益现象;随着复介电正虚部的增大,透射峰出现单调衰减,而随着复介电负虚部绝对值的增大,透射增益达到一极大值,随后减小;在不同介质层引入复介电常量引起透射峰的透射率衰减或增益强度不同。这些特性对设计光放大器、衰减器等新型光学器件有一定的参考价值。     

《在路上》中的西部情结

当代美国作家杰克.凯鲁亚克的小说《在路上》被誉为是"垮掉的一代"的宣言书和《圣经》,它是美国文学中诠释西行主题的经典之作。小说以主人公萨尔对东部厌倦———对西部的幻想———西部梦想的幻灭为线索,体现了"垮掉的一代"时代背景下所贯穿于作品当中的西部情结的主题。这一主题的凸显过程也暗含了美国文学中对东部和中西部所持的对立的传统看法,即东部是欧洲堕落的化身,而中西部是原始道德的发源地,这种西部情结背后深藏的是"垮掉的一代"对现实的不满、对社会的抗议和对自由精神的追求。     

一类n阶高次微分方程的特解

在复数域内,利用特征方程的特征根给出了一类n阶常系数高次微分方程求特解的方法,推广了已有文献的结果.     

基于复杂网络和粒子群算法的滤波与轨道优化模型

嫦娥三号已成功完成软着陆,其着陆准备轨道的位置和着陆轨道及其控制策略是嫦娥三号月球着陆的关键问题。运用天体物理相关理论及智能优化算法构建了基于复杂网络的滤波模型和基于粒子群算法的着陆轨道优化模型,并通过matlab计算及matlab仿真,给出了着陆轨道及其控制策略。     

Development of learning to learn skills in primary school

In Finland, schools’ effectiveness in fostering the development of transversal skills is evaluated through large-scale learning to learn (LTL) assessments. This article presents how LTL skills—general cognitive competences and learning-related motivational beliefs—develop during primary school and how they predict pupils’ CPS skills at the end of sixth grade. The six-year follow-up of 608 pupils shows that cognitive competences demonstrated in the beginning of the first grade in a learning preparedness test predict both later cognitive LTL competences and CPS, but their development is not fully determined by earlier individual differences in learning preparedness in the first grade. Motivational beliefs begin to be related to cognitive LTL performance gradually from age 10 on, and they may have a slightly stronger effect on CPS than on cognitive LTL performance. It is concluded that the development of CPS is partly depending on pupils’ initial learning preparedness and the development of their LTL skills.     

国外海岸带韧性研究进展及其对中国的启示

海岸带韧性可为沿海地区应对全球气候变化与人类活动压力的复合风险提供新的理论源泉和分析视角,对保障沿海地区可持续发展安全具有重要意义.本文在解析海岸带韧性概念内涵的基础上,剖析了以社会生态系统、复杂适应系统等理论为支撑的海岸带韧性理论框架,比较了现有4类评价方法,进而厘清了要素型、过程型和复合型3类评价指标体系的特点,阐...     

The development of students critical thinking abilities and dispositions through the concept mapping learning method – A meta-analysis

Our meta-analysis investigates the effectiveness of the concept mapping method compared with the traditional teaching method, for the improvement of critical thinking ability and disposition outcomes. We included studies measuring students' critical thinking through standardised tests, comparing an experimental (concept mapping) group with a control (traditional teaching) one. Effect sizes for critical thinking ability and disposition outcomes were pooled with a random-effects model. We included in our meta-analysis 21 studies (108 comparisons) involving 1695 students. The concept mapping method was more effective than the traditional teaching method at posttest for the improvement of critical thinking ability (g = 0.531, 95% CI 0.279 to 0.783) and disposition (g = 0.648, 95% CI 0.266 to 1.031). Heterogeneity was moderate to high, Egger's test did not indicate any evidence of publication bias; however, both visual inspection of the Funnel plot and Duval and Tweedie's trim and fill method indicated potentially three missing studies for critical thinking ability and two for critical thinking disposition. Additionally, we analysed the potential moderating effect of students' demographic characteristics, educational conditions, concept mapping elaboration methods and allocation type. Allocation type was a significant moderator, having a strong effect on concept mapping for critical thinking abilities in randomised studies (g = 0.739, 95% CI 0.356 to 1.122), but its effect is low in non-randomised studies (g = 0.265, 95% CI 0.014 to 0.517).     

Why do students strive to outperform classmates? Unpacking their reasons for pursuing performance goals

Achievement goal theory has evolved since introduced about 40 years ago. One of its newer variants is the goal complex model. It assumes that each achievement goal (i.e., performance or mastery) can be pursued for many reasons and, more provocatively, that the goal’s effects depend partly on why it is pursued. Clearly, the first task for this area is to identify likely goal pursuit reasons, develop and validate a measure of reasons, and chart the influence of those reasons. Progress remains limited, however. Nearly all studies have considered only a small set of reasons suggested predominantly by self-determination theory, overlooking several other plausible reasons. Nor is there an established measure of goal pursuit reasons. To overcome those limitations, the current study validated and tested a new goal complex measure that includes several additional goal pursuit reasons, both personal (e.g., pride) and social (e.g., to make close others proud, or to help or serve others) in nature. Two culturally distinct samples of university students – one from the USA (n = 400), the other from Thailand (n = 404) – completed the measure with performance goals in mind and then reported a diverse array of educational outcomes. Their results converge for the most part. In each sample, the new measure proved to have good structural validity and psychometric properties. Several goal complexes, including the new social ones, showed unique and often desirable relationships with outcomes, too. The findings raise several research directions and implications for achievement goal theory.     

复杂产品系统研发项目合作伙伴选择优化

合理选择合作伙伴是复杂产品系统研发项目的关键成功因素之一。在对伙伴选择影响因素进行总结的基础上,选取费用、时间、风险及合作伙伴间的协作关系作为主要考虑因素,建立了复杂产品系统研发项目伙伴选择的多目标整数规划模型。该模型旨在为各子项目找到整体最佳的合作伙伴组合,以实现总项目失败风险最小化和总项目费用与拖期惩罚最小化。设计了遗传算法用于求解该伙伴选择数学模型,并通过实际案例证实了该模型的实用性和算法的有效性。     

干系人私人关系、知识共享行为对复杂产品研发绩效的影响

在文献回顾的基础上,提出了干系人私人关系的三个构成:感情、人情和面子,探讨了干系人私人关系的三个构面、知识共享行为和复杂产品研发绩效之间的关系,构建了理论模型,并以复杂产品研发团队的干系人为调查对象对模型进行了实证研究。研究结果显示:干系人的感情、人情和面子均对知识共享行为有显著的正面影响,感情和面子对复杂产品研发绩效有显著正面影响,知识共享行为对复杂产品研发绩效有显著正面影响。此外,研究结果还表明,知识共享行为在人情和复杂产品研发绩效之间起到了完全中介作用;知识共享行为在感情和复杂产品研发绩效及面子和复杂产品研发绩效之间分别起到了部分中介作用。