Precision measurements and fundamental constants

Recent developments in the techniques for making precision measurements and their use in the determination of the fundamental constants are reviewed. Particularly noteworthy developments are clocks with high stability, the proposed redefinition of the meter in terms of the standard for time, and the increased precision with which electrical standards can be maintained. The relevance of precision measurements to tests of general relativity is briefly discussed.     

Information: the ultimate frontier

Although long-term forecasting is best left to science fiction writers, scientists can illumine basic technological trends, as in the 100-year scenario presented here. Computers will continue the "small is beautiful" trend, but they are not likely to follow the semilog trail because extrapolation from the current base would lead to absurdities such as a computer cost of 3/100 of a cent. To achieve inexpensive high speed and Lilliputian size, new techniques are likely to replace silicon technology. The ultimate computer might be biological and patterned on DNA. Future computers will reacquire information when needed rather than store it, and we will see personalized products at mass production prices. Light wave communication will broaden communications exchange, but software that is more friendly to human users will be needed. By taking over knowledge distribution, electronic information systems will let universities concentrate on new knowledge. More importantly, they will expand everyone's right to information and free expression through the existing media system and to protection from misuse of information by others.     

我国小麦生产的技术进步率测算与分析——基于随机前沿分析方法

为了解我国小麦生产的技术进步现状及测算小麦生产的技术进步率,本研究利用随机前沿分析方法,运用1998—2014年全国15个小麦主产区的投入与产出面板数据对小麦生产的技术进步率进行了测算研究。研究结果表明:技术进步对小麦生产的支撑主要包括优良品种的选育与更新换代、栽培技术的推广、机械化生产技术及病虫害防治技术;小麦生产的年均技术进步率为1.242 2%,技术进步效果显著;小麦各主产区的技术进步率存在较明显的区域差异,大部分主产区的技术进步率为正值,而四川、云南的技术进步率则为负值,因此,加强小麦生产技术的区域间合作是非常有必要的。     

样地林木生物量精度评定的研究

为了评定样地林木生物量的估算精度,利用方差--协方差传播律,导出平均断面积法、每木树高胸径法和径阶平均断面积法计算样地林木生物量的精度评定公式;应用实例,分析模型误差、树高误差和胸径误差对样地生物量的影响,并对3种计算样地林木生物量公式的精度进行比较.根据一尾叶桉林样地中90棵树木的分析结果,平均断面积法的精度为2.18%,每木法的精度为1.99%,径阶均值法的精度为1.89%.具体结论为:①样地林木生物量的精度可用公式进行评定;②每木法和径阶均值法计算的样地生物量精度较高,平均断面积法计算的样地生物量精度较低;③样地林木生物量的估算误差,主要受模型参数误差的影响,受树高和胸径误差的影响处次要地位.     

电测法测试结构用重组竹弹性常数的研究

利用电测法对结构用重组竹12个弹性常数进行了测定,并对变异较大的3个泊松比进行了修正,验证了电测法在重组竹弹性常数测定中的适用性,最后将重组竹和几种木材的弹性常数进行了对比。结果表明,重组竹弹性模量关系为ELERET,各弹性常数变异系数在12.723%~28.944%范围内波动;经验证,12个弹性常数满足正交各向异性模型的限制条件,但由于材料的非均质性导致修正后的泊松比理论值和实测值误差稍大;重组竹弹性常数比普通木材的弹性常数大。     

实用主义的演变及其基本要义

长期以来，人们对实用主义有很多的误解。本文从实用主义的缘起和演变，它与传统哲学在本体论上的区别，作为澄清意义的方法以及实用主义真理现来阐述实用主义，表明实用主义的思想价值。