非完整统计在完全开放系统中的概率分布

非完整统计是非广延统计力学发展的一个分支。在简要介绍非完整统计思想的基础上,根据最大熵原理,结合非完整熵推导了完全开放系统中的概率分布和配分函数,以此分布可以直接得出其他实际可用的6种统计分布。这对研究多粒子体系的复杂物理系统提供理论依据。     

Fractional-order global sliding mode controller for an uncertain quadrotor UAVs subjected to external disturbances

In the present paper, the problem of designing a global sliding mode control scheme based on fractional operators for tracking a quadrotor trajectory is investigated. The model of the quadrotor system is given with disturbances and uncertainties. To converge in short finite time of the sliding manifold, a classical quadratic Lyapunov function was used and also a global stabilization of the quadrotor system is ensured. The proposed controller can be ensured the robustness against external disturbances and model uncertainties. Some scenarios are illustrated in this paper. Finally, a comparative study to three other controllers is provided to show the validity and feasibility of the proposed method.     

浅谈多媒体技术在高校教学中的应用

随着计算机的普及和高校教学的改革,多媒体技术已被广大高校充分运用到各类学科的教学中,大大提升了课堂教学质量和效率,提高了教师教学和学生学习的积极性,丰富了高校教学的教学手段和教学方式。本文首先阐述了多媒体教学的含义;然后论述了多媒体技术在高校教学中的重要性及应用策略;最后,探讨了多媒体技术在高校教学中的应用。     

Teachers’ self-reported beliefs on developmentally appropriate and inappropriate practices in grade K-4 EFL classrooms

This study investigated the perceived beliefs and reported practices of fourth-grade English teachers in primary (elementary) public schools in Turkey. Significantly, it aimed to examine the participating K-4 English as a foreign language (EFL) teachers’ beliefs about the developmentally appropriate and inappropriate practices, discover the possible factors that might influence the planning and implementation of those instructional activities, and lastly, find out whether there is any correlation between the self-reported beliefs and practices. A sample of 158 EFL teachers teaching fourth-grade classes at Turkish public schools (primary level) participated in the study. Data were gathered from the Teacher Beliefs and Practices Survey: 3–5 Year Olds based on 1997 National Association for Education of Young Children's Developmentally Appropriate Practice (DAP) guidelines and focus group interviews. The findings revealed that future teacher training programmes should promote DAPs and enhance teachers’ skills to implement them effectively in the young learners' language classrooms.     

社会保险降费政策对企业技术创新的影响

在国内外经济下行压力下,“减税降费”已成为增强企业活力,促进高质量发展的重要手段。不同于其他税费政策改革,社会保险降费政策会通过财务资本和人力资本两个方面影响企业发展。然而,该政策对企业高质量发展的影响及作用机制尚不明晰。基于此,本文以各地级市政府实施的社会保险降费政策作为外生事件,运用双重差分模型,从企业技术创新的微观视角,考察社会保险降费政策对企业高质量发展的影响。研究结果显示,社会保险降费政策有利于提高企业技术创新水平。进一步分析发现,社会保险降费政策主要通过增加研发投入和优化人员结构推动企业技术创新,但两条路径的影响存在差异：其通过研发投入可以同时促进企业实质性创新和策略性创新,其通过人员结构仅促进企业实质性创新。最后,异质性分析发现,相较而言,上述影响在国有企业及所处监管环境较好的企业中更为显著。本文的研究结论既为“劳动经济学与微观企业行为”领域的研究提供了增量证据,也为“减税降费”等营商环境优化措施提供理论支持。     

缩微胶片档案醋酸综合症监测研究—以中国民族图书馆为例

我国档案馆、图书馆等机构保存了大量的缩微胶片档案,醋酸综合症是影响缩微胶片档案寿命最为重要的原因。近30年来,缩微胶片档案一直受到醋酸综合症的困扰,如何及时监测醋酸综合症是影像档案保护研究的热点和难点。本文对中国民族图书馆缩微胶片档案的保存现状进行调研,以AD试纸监测醋酸综合症发生、发展及其对缩微胶片档案的影响。研究发现,AD试纸能够准确监测醋酸综合症的发生,在缩微胶片档案保护中起到预示和监测作用,能够更好地防治醋酸综合症。     

村民自治中的贿选问题及其治理

近年来贿选之风愈刮愈烈,严重影响了村民选举的公正性,阻碍了村民选举的健康发展,但是贿选并不是不可避免的.对贿选作出界定,从内外两方面分析贿选的成因,可采取多种措施、多角度对贿选进行治理,遏制其发生.     

论学生自主学习能力的培养

自主学习有三个特征:能动性、独立性、创新性。本文论述了学生自主学习能力形成需要的条件,即激发学习动机、营造积极活跃的课堂氛围、开发积极的评价制度。