Dynamic Stability Analysis of Cages in High-Speed Oil-Lubricated Angular Contact Ball Bearings

To investigate the cage stability of high-speed oil-lubricated angular contact ball bearings, a dynamic model of cages is developed on the basis of Gupta’s and Meeks’ work. The model can simulate the cage motion under oil lubrication with all six degrees of freedom. Particularly, the model introduces oil-film damping and hysteresis damping, and deals with the collision contact as imperfect elastic contact. In addition, the effects of inner ring rotational speed, the ratio of pocket clearance to guiding clearance and applied load on the cage stability are investigated by simulating the cage motion with the model. The results can provide a theoretical basis for the design of ball bearing parameters.     

陌生人社会的邻里交往

邻里互动是社区共同体存在的基础,转型期的中国城市社会是否可以培育出“社区共同体”？针对这一问题,本文以石家庄某个典型的新建商品房小区为研究田野,通过深入访谈、参与观察以及问卷法等揭示出转型期背景下城市邻里交往的真实状态,分析了社区场域下行动者的行为逻辑,发现邻里交往行为是嵌入于整个社会的文化背景中的,邻里互动使得“社区共同体”的构建成为可能。     

鲜于中山国史杂考

在史料中,鲜于中山国废王"胜、尚"并称,相邦之一"蓝诸君"又称"望诸君",族名仇由氏又称"由、仇繇、夙繇、仇犹"等。利用古音知识并证之以现实方言,则庶几能得原委。     

海外华人的语言生活与华文教学的内容、方法和目标

海外华人的语言生活尤其是其中的方言因素对华文教学之内容、方法与目标产生直接的影响。在确立华文教学之内容、方法与目标时,应对海外华人的语言生活予以足够的重视,不仅要从世界汉语教学大趋势的角度考虑,也要兼顾华人社会沟通的需要、历史文化传承的需要,并遵循语言发展与传播的基本规律。     

English Proficiency,Identity, Anxiety,and Intergroup Attitudes: US Americans’ Perceptions of Chinese

Guided by the Common Ingroup Identity Model and Berry’s acculturation framework, this study examined the roles that perceptions of language proficiency, cultural identity, and communication anxiety had on intergroup attitudes and stereotypes in the American–Chinese contact context. Serial mediation analyses with 10,000 bootstrap samples revealed that perceived English proficiency of a Chinese contact had significant indirect effects on affective and behavioral attitudes toward Chinese through American participants’ perceptions of their contact’s host and home culture identification and communication anxiety. Perceived English proficiency had an indirect effect only on positive stereotypes through the Chinese contact’s perceived identification with home culture.     

Are gait characteristics and ground reaction forces related to energy cost of running in elite Kenyan runners?

The aim of this study was to determine whether gait cycle characteristics are associated with running economy in elite Kenyan runners. Fifteen elite Kenyan male runners completed two constant-speed running sets on a treadmill (12 km ·h^?1 and 20 km ·h^?1). VO₂ and respiratory exchange ratio values were measured to calculate steady-state oxygen and energy cost of running. Gait cycle characteristics and ground contact forces were measured at each speed. Oxygen cost of running at different velocities was 192.2 ± 14.7 ml· kg^?1· km^?1 at 12 km· h^?1 and 184.8 ± 9.9 ml· kg^?1· km^?1 at 20 km· h^?1, which corresponded to a caloric cost of running of 0.94 ± 0.07 kcal ·kg^?1·km^?1 and 0.93 ± 0.07 kcal· kg^?1· km^?1. We found no significant correlations between oxygen and energy cost of running and biomechanical variables and ground reaction forces at either 12 or 20 km· h^?1. However, ground contact times were ~10.0% shorter (very large effect) than in previously published literature in elite runners at similar speeds, alongside an 8.9% lower oxygen cost (very large effect). These results provide evidence to hypothesise that the short ground contact times may contribute to the exceptional running economy of Kenyan runners.     

粤语与美语地区性方言比较研究

当今世界英语以美国英语为主导,有美语化倾向;与此相类似的是,粤语在汉语各方言中也起主导的作用并已“颇具规模”。追寻其原因,不论是从语言与文化的相互关系、相互作用的角度来探讨,抑或是从跨文化的观点来推敲,都可寻到其根源。其中,除涉及到语言因素之外,还跟文化、历史、地理、政治甚至是经济等因素有关。本文尝试就这些方面(主要侧重于粤语借词的“进出口”现象以及澳洲英语的美语化现象)进行探讨。     

墨子里籍东、西鲁论争一瞥--读萧鲁阳方言研究力作

拜读萧鲁阳方言研究力作,汇集《墨子》书中鲁山方言习俗,概述墨子里籍东、西鲁论争态势。从方言习俗角度比较鉴别,进一步论证墨子里籍在河南鲁山,非山东曲阜、滕州。期待“上德”之史学家：尊重历史真实,破解墨子里籍;了断地域成见,展示大家风范。     

对数学课程中有关数学文化的思考

数学文化呈现的是开放、多元和动态的数学内部及其与外部的联系.数学文化价值体现在如下4个方面:数学自身价值、科学价值、社会价值与精神价值.基于这样的数学文化观念,有关数学文化课程的设置就应充分重视与学生的文化背景及数学现实的联系,注重数学与其它学科的联系,注重数学内部知识结构之间的联系.     

闽语的“卜”和“捶”

闽语的“卜”和“挃”都是“要”的意思,是口语中的常用词,也是未见于外方言的闽语特征词。但是在各地闽语中,“卜”和“挃”不论是用字还是读音、意义或用法都有许多差异。通过对闽语的“卜”和“挃”的分析,研究认为,方言词汇的研究应着力于常用词,尤其是口语常用词。但是,常用词的比较研究,不能只取某一个词义作孤立比较,而必须从整个义位的系列并联系义素的组合,作为一个系统来考察,才能认识单个常用词的完整含义和功能。而且,常用方言词的比较。应对内比较同区方言之间的异同,对外比较方言与古今通语的异同,如此才能准确提取归纳方言的特征词及其历史层次中的语言事实与演变规律。最后,对方言常用特征词的词源考证很重要,但必须经过音韵论证、字义分析和古籍用例引证等环节,这是毋庸置疑的。