Experimental Study of Structure Shock Vibration in Soil Caused by Explosion of Conventional Weapons

When hitting underground structures directly or exploding in rock-soil media near underground structures, the conventional weapons with large charge weight will make underground structures be subjected to strong shock vibration and cause personal casualty and damage of precision electronic equipments. The shock vibration has become one of the cardinal killing means of weapons. However, the existing methods of predicting structure shock vibration are limited evidently. In this paper the coupling coefficient of acceleration in clayey soil is obtained firstly. Subsequently based on repeated experiments of chemical explosion, after dimension analysis and by using method of multivariate stepwise regression, the calculation formulae of shock vibration acceleration for the underground structure are obtained finally. The formulae consider top and side explosion respectively, taking into account the effects of penetration depth, charge weight, distance to explosion center, rock-soil media, size of structure and buried depth. They are easy to use with high practicability and degree of confidence, and can provide credible evidence for prediction of shock vibration and vibration isolating design of underground structure.     

英语修辞之比喻及其翻译技巧

修辞格在翻译中是一个最为棘手的问题，理论和实践都说明了这一点，而比喻修辞格的使用是最频繁的。本文论证了英语修辞的两种译法，即直译法和意译法，以及直译基础上的意译这一观点。文章用丰富的例子说明这些译法的话要性、适应性和可行性。     

互联网上5个免费中国专利数据库的比较研究

本文对5个常用的免费中国专利数据库进行了比较，并结合检索实例指出了它们的异同，以便为读者正确选择和使用中国专利数据库提供参考．     

A man on the inside: Unlocking communities as complementary assets

Since Teece's seminal paper explaining who were the gainers from technological innovation, increased globalization and the information and communication technology revolution have brought new ways for firms to organize and appropriate from innovation. A new more open model of innovation suggests that firms can benefit from sources of innovation that stem from outside the firm. The central theme of this paper is how firms try to unlock communities as complementary assets. These communities exist outside firm boundaries beyond ownership or hierarchical control. Because of practices developed by communities to protect their work, firms need to assign individuals to work in these communities in order to gain access to developments and, to an extent, influence the direction of the community. Using network analysis we show that some software firms sponsor individuals to act strategically within a free and open source software (FOSS) community. Firm sponsored individuals interact with more individuals than interact with them, and also they seek to interact with central individuals in the community. However, we can see differences in how individuals interact, depending on whether their affiliation is with a dedicated FOSS firm or an incumbent in the software industry. Apparently, some firm managers believe they need ‘a man on the inside’ to be able to gain access to communities.     

免费师范生三大报考动机的调查研究——以陕西师范大学为例

通过对陕西师范大学546名免费师范生的调查发现,免费师范生报考免费师范专业的三大动机分别是两免一补、实现教师职业理想和就业有保障。其中,就业有保障动机最强,两免一补次之,实现教师职业理想相对较弱。三大报考动机之间具有极其显著正相关关系(P≤0.01)。不同群体免费师范生之间的三大报考动机还存在着一定的显著差异(P≤0.05)或极其显著差异(P≤0.01)。这些对师范大学、各省(市、自治区)做好师范生免费教育工作都具有一定的启示作用。     

Development of integrated precision vibration-assisted micro-engraving system

A novel precision vibration-assisted micro-engraving system was developed by the integration of fast tool servo and ultrasonic elliptical vibration system, in which the flexure hinge was designed to avoid backlash and PID control algorithm was established to guarantee specific precision. Apart from experimental validation of the performance of the system, various micro-V-grooves cutting experiments on aluminum alloy, ferrous material and hard cutting material were performed, in which Kistler force sensor was used to measure cutting force. Through experiments, it was clear that the vibration-assisted micro-engraving system can ensure good quality of micro-V-grooves and reduce cutting force by about 60% compared with traditional removal process without ultrasonic vibration.     

平板叶片的相关激励响应试验

为了研究不同频率的激振力叠加作用下平板叶片的位移响应变化,在平板叶片上选取激励点和多个响应点进行相关性激励试验。试验中,首先运用设计的加法器对频率为112、280和583 Hz的简谐力分别进行叠加,然后以压电陶瓷片作为激振器对平板叶片进行激励,同时以压电陶瓷片作为感应器采集位移响应,最后应用谱分析方法对位移响应进行分析。通过对比不同频率的激振力叠加作用下的位移响应自功率谱幅值,发现自功率谱幅值比单一频率激振力作用时有所降低,并且降低的程度和与其叠加的激振力频率的大小和个数有关,叠加的个数越多,降低的程度越大。     

卡梅伦政府教育新政:创建“自由学校”,确保教育公平

2010年6月18日,英国新任首相卡梅伦出台一项教育新政,允许个人和组织创办自由学校,其办学理念可简单概括为政府掏钱、私人管理,其灵感主要来自瑞典的自由学校以及美国的特许学校。创建自由学校主要缘于英国传统教育的弊端及贫富教育差距的不断扩大。英国政府已经设立了5 000万英镑的专项基金,作为2011年3月31日前创建自由学校的启动资金。该计划宣布后,立即有700多个团体表示有兴趣,这对改进英国教育的公平将影响深远。     

国际经验对海南自由贸易港规划建设的启示

海南自由贸易港规划建设不仅是海南自身发展的需要,也是中国深化改革、扩大开放、实现经济转型及应对国际竞争与挑战的重要战略举措.本文在总结与归纳自由贸易区的含义、类型以及发展经验的基础上,对海南自由贸易港建设的基础与条件、功能与作用、属性与类型、产业选择、空间结构、监管模式、政策法规、营商环境以及风险防控等方面作了系统分析...     

用经验模式分解和重标极差分析法进行摩擦振动信号分析

为提取和表征摩擦振动的特征信号,在摩擦磨损试验机上进行以船用柴油机缸套和活塞环为材质的摩擦副摩擦磨损试验.应用经验模式分解(Empirical Mode Decomposition, EMD)对非线性、非平稳的摩擦振动信号进行分解,获得若干个本征模式函数(Intrinsic Mode Function, IMF).从中选择反映摩擦振动特征的IMF重新合成摩擦振动特征信号,应用重标极差分析法对摩擦振动特征信号进行分析,得到线性回归谱和Hurst指数.结果表明,EMD能够实现摩擦振动特征信号的提取,重标极差分析法可以分析摩擦振动信号的渐变过程,提取摩擦振动信号的特征.该方法可为基于摩擦振动信号的机械摩擦副摩擦磨损行为的研究提供新的途径.