A comparative analysis of multi-output frontier models

Recently, there have been more debates on the methods of measuring efficiency. The main objective of this paper is to make a sensitivity analysis for different frontier models and compare the results obtained from the different methods of estimating multi-output frontier for a specific application. The methods include stochastic distance function frontier, stochastic ray frontier, and data envelopment analysis. The stochastic frontier regressions with and without the inefficiency effects model are also compared and tested. The results indicate that there are significant correlations between the results obtained from the alternative estimation methods.     

浅谈电子电器的通用检修技术

试图寻找简单的只用电子电路基础知识就能掌握的电子电器的通用检修技术,当种类繁多的电子电器出现故障时能及时修复。据此提出:练就直观检查电子电器技术指标的能力;突出使用示波器跳跃式寻迹“标准信号”缩小查故障的范围;在熟悉常用元件性能、损坏后电路特征的基础上,用电压、电阻测量法或替换法找出故障的元件,以期达到快速检修的目的。     

列宁社会保险思想探源

社会主义社会保障体系的理论来源是马克思在《哥达纲领批判》中描绘的社会公有产品的分配蓝图。在具体论证和建立社会保障新体系的实际工作中,列宁发挥了巨大的作用。从19世纪末开始,列宁一直关注俄国劳动者的生活状况,领导无产阶级争取各项社会保障权利。在领导俄国无产阶级进行经济斗争的过程中列宁逐渐形成工人国家社会保险思想,并对后来苏联社会保障实践产生了重要影响。     

钙镁电气石检测特征探析

在宝石检测中发现，钙镁电气石呈黄绿色，与祖母绿相似。利用折射仪、红外光谱仪等手段测试确定为电气石。采用X射线衍射和电子探针分析（Cr2O含量仅0．08％），结果定名为钙镁电气石。它的主要鉴定特征与不同变种的电气石近似，与其它相似宝石的特性特征区别明显。     

基于Internet的自适应测试系统的设计和开发

目前Internet的普及为学习提供了一个广泛而且便利的新途径，作者提出了一个基于Internet的网上自适应测试系统的设计方案，并创建了一个自适应测试的环境。本文介绍了该系统的总体设计框架，并介绍了自适应测试的原理及实现思路。     

Tracing worked examples: effects on learning in geometry

Previous research has verified the benefits obtained when learners trace out worked examples with the index finger. Our study conducted two experiments to explore the reasons for this phenomenon and its generalizability. Experiment 1 compared the learning effects among tracing, non-tracing, and cueing methods. The cueing method was included to isolate the variable of drawing attention. Students employing the tracing method obtained higher transfer test scores compared to those employing the cueing and non-tracing methods, rating the far transfer test as easier. The tracing effect was verified to have a greater impact on learning than solely focusing learners’ attention. Experiment 2 compared the learning effects among three methods – tracing with the index finger, tracing with a computer mouse, and observing others tracing. Students who merely observed tracing obtained lower far transfer scores than those who traced either with their finger or with the mouse, rating the tests as more difficult. There was no significant difference between the other two groups. Tracing promotes learning more than merely observing tracing. The learning benefits of tracing partly stem from the fact that it is action-based and can be generalized to mouse tracing.     

确定主截面内非寻常光传播方向的一种方法

文中用费马原理给出了光沿主截面入射时,非寻常光在各向异性介质中的传播方向,证明了当光轴与法线之间夹角为φ时,入射光的入射角i与非寻常光之折射角θ之间的关系。     

臭氧和臭氧层

臭氧层对维持地球上的生态平衡起着重要作用 ,了解臭氧层的破坏机理和保护臭氧层是我们的共同责任     

虚拟演播室技术及其应用

虚拟演播室技术是目前电视领域里应用的比较广泛而且比较成熟的技术。它的应用大大减少了制作节目的成本和制作的周期，更重要的是为节目制作场景提供了更广阔的想象空间。同时也克服了传统布景不宜随便搬动，灵活性差，场地不能重复利用的缺点。     

白桦根的木材解剖学研究

对白桦根次生木质部进行木材解剖学研究，发现其为散孔材，管孔多数为复管孔，少数为单管孔，为同形射线，导管分子穿孔板类型为梯状穿孔板，离析材料中韧型纤维丰富。