Assessment of the phase synchronization effect in modal testing during operation

The impact-synchronous modal analysis (ISMA), which uses impact-synchronous time averaging (ISTA), allows modal testing to be performed during operation. ISTA is effective in filtering out the non-synchronous cyclic load component, its harmonics, and noises. However, it was found that at operating speeds that coincide with the natural modes, ISMA would require a high number of impacts to determine the dynamic characteristics of the system. This finding has subsequently reduced the effectiveness and practicality of ISMA. Preservation of signatures during ISTA depends on the consistency of their phase angles on every time block but not necessarily on their frequencies. Thus, the effect of phase angles with respect to impact is seen to be a very important parameter when performing ISMA on structures with dominant periodic responses due to cyclic load and ambient excitation. The responses from unaccounted forces that contain even the same frequency as that contained in the response due to impact are diminished with the least number of impacts when the phase of the periodic responses is not consistent with the impact signature for every impact applied. The assessment showed that a small number of averages are sufficient to eliminate the non-synchronous components with 98.48% improvement on simulation and 95.22% improvement on experimental modal testing when the phase angles with respect to impact are not consistent for every impact applied.     

杜威教育目的论的思考

概述杜威教育目的论的提出及其客观性、灵活性和统一性特点,阐述并分析杜威教育目的论现代意义的批判性、特殊性及不足与启示,指出杜威教育目的论的研究价值和实践意义。     

论科学究竟是什么——从科学的思维和视角思考教育

正如英国科学家A.F.查尔默斯(Alan F.Chalmers)所著的书《科学究竟是什么》书名所提出的疑问"科学究竟是什么"一样,我们每个有着好奇心的人都有这样的疑问。这个问题也是所有研究科学以及研究科学教育的人首先需要回答的问题。查尔默斯就当代西方一些主要的科学哲学家如波普尔、拉卡托斯、费耶阿本德等对科学究竟是什么这个问题的回答作了简明扼要的介绍,并在介绍其他科学哲学家的观点的同时也提出了理性的批判,同时阐明了查尔默斯他自己的观点。通过对科学究竟是什么的各种论述进行阐述,力图使教育工作者能够对究竟什么是科学这个问题以及如何把科学运用到教育教学当中有一个初步了解。     

A survey of the use of ethnographic methods in the study of libraries and library users

A survey and analysis of the use of ethnographic methods in studies of libraries and library users identified a total of 81 studies. Five main types of ethnographic research methods were identified: observation, interviews, fieldwork, focus groups, and cultural probes. The survey shows a recent increase in the use of ethnographic methods in libraries, and identifies an emerging genre of studies associated with library planning that uses rapid ethnographic methods to investigate libraries and their users as part of planning processes. The survey supports comparison across ethnographic studies, settings, and methods; enables the growth of ethnographic methods as a research method in libraries; and provides material for library and information science curriculum development in this area. A bibliography of the studies used in the analysis is provided in Appendix A, and includes a number of gray literature reports and online publications.     

谈卢梭教育思想超越时代的现代教育特征及其意义

卢梭(Rousseau,1712-1778)是启蒙运动时期著名的教育理论家。他的教育思想绝大多数都在其著作《爱弥儿》中得以体现,并且与现代教育理念具有很大的共同性。可以说,卢梭的教育思想具有非常强的时代超越性,对现代教育影响非常深远,并对我国教育实践具有巨大的启发意义。     

谈休谟道德理论的历史影响及其对我国道德教育之启示

目前,大多数研究者对中国传统文化的道德观念研究比较深刻,而对于西方所推崇的一些道德理论的研究还不是太多,因而,通过对休谟的著作《道德原则研究》的探索,对其道德理论进行分析与阐述,有利于读者对休谟的道德理论有一个初步的了解。     

对湖南省普通高校教师参加体育活动的现状及其影响因素探析

通过调查,发现湖南省高校普通教师每周参加体育活动的次数大多在1～2次,每次体育活动的时间多为30 min,选择参加的体育活动项目的主要有:跑步、散步、足篮排三大球、游泳等.影响湖南省普通高校教师参加体育活动的主要因素是工作压力大,没有充分时间;对体育锻炼身体,增强体质认识不足;体育知识欠缺,不知如何安排自己的体育活动;场地缺乏,没有体育活动空间;高校不重视教师参加体育活动的管理和指导等.     

Learning environment associated with use of mixed mode delivery model among secondary business studies students in Singapore

At many teacher education institutes around the world, preservice teachers are empowered to use pedagogical tools and strategies that engage their students. We used a modified version of the Constructivist Learning Environment Survey (CLES) to evaluate the effectiveness of a pedagogical model known as the Mixed Mode Delivery (MMD) model in terms of the CLES’s five scales of personal relevance, uncertainty, critical voice, shared control and negotiation. Comparisons were made between 2,216 secondary school students taught by the preservice teachers in an MMD group and 991 students in a control group in terms of the relative magnitudes of the gap between the actual and preferred learning environment in students’ school classrooms. The findings supported the positive impact of using MMD in terms of students’ perceptions of their classroom environments for all CLES scales.