基于单开链运动相容性的过约束机构分析新方法

提出一种判断过约束机构的新方法 ,它基于如下的单开链运动相容性准则 :若对于主动输入的任意取值 ,2个单开链始终满足其两端轴间距相等 ,轴间夹角相同 ,对应的轴长之差为常量 ,则此二单开链可构成一个封闭回路 ,该回路为过约束机构。该法操作简单 ,其特点是变量间输入输出关系先于过约束性得到。过约束机构的寻找可由局部相容性关系入手找出部分运动学关系 ,进而逐步得到满足所有相容性关系的过约束性条件与运动输入输出规律。用该法给出了 4R过约束机构的寻找方法 ,同时对一个 4R2 P机构进行了过约束性判定。     

EC301压缩机扩容改造项目低压段离心级试验设计

在轴汉压气机试验台上进行全尺寸在元流离心级的试验，需进行适台设计，本文详细阐述了适对设计思想及过程，并对三元注台轮的级特性进行了分析，为压缩机的扩容改造节可靠的依据。     

Modification of epoxy asphalt by low-doping PE-GMA and PE-MAH

Low-density polyethylene grafted glycidyl methacrylate (PE-GMA) and low-density polyethylene maleic anhydride (PE-MAH) are low-cost commercialized polymeric materials. Because of their low viscosity, molecular flexibility, solubility parameters, and polarity similar to asphalt or epoxy resins, PE-GMA and PE-MAH are added to epoxy asphalt (EA) to improve the compatibility and toughness of EA. The microstructure, viscosity, thermal stability, dynamic mechanical behavior, and mechanical properties of PE-GMA and PE-MAH modified EA were investigated. Smaller and more uniformly distributed asphalt particles were formed in mixes with lower PE-GMA or PE-MAH content. The polymer dispersity index of the modified EA is 1.1–1.4 lower than that of the pure EA, and compatibility is significantly improved. The reason is that PE-GMA and PE-MAH are polyethylene with polar functional groups, and their molecular structure includes both polar functional groups and nonpolar polyethylene chains, improving the compatibility between polar epoxy resin and nonpolar asphalt in EA. In addition, the incorporation of PE-GMA or PE-MAH effectively improves the low-temperature toughness of EA. It also has high damping performance and tan δ, improved the durability and comfort of EA pavement.     

煤矿综采工作面“三机”设备配套选型与计算

介绍了煤矿综采工作面"三机"配套设备选型的一些基本原则,并结合实际情况,通过举例来说明"三机"设备选型的基本计算,为煤矿综采工作面"三机"设备的选型提供理论依据,给后续的配套工作提供了参考。     

一项评估液压油能否混用的新规程——ASTM D7752-2011简介与评述

ASTM D7752-2011是一项用于评估液压油能否混用的标准规程,由ASTM D02石油产品和润滑剂技术委员会D02.N0.09相容性分技术委员会制定。该规程规定通过ISO 13357-1过滤性试验来评估液压油混合后的相容性,这是迄今为止液压油混用研究领域里的一项最全面、最完善的标准规程。依据ASTM D7752-2011原文对该标准规程进行了介绍,对涉及到的ISO 13357-1过滤性试验也给出了详细的操作说明,此外开展了该规程与国内同类方法 GJB 562-1998和Q/SHGQ 01.475-2002的对比分析。建议国内有关单位在进行液压油的混用操作前参考使用该标准规程。     

不同废纸纤维增强聚乳酸基复合材料性能研究

通过纤维分析仪、傅里叶变换红外光谱仪（FT-IR）、扫描电镜（SEM）研究4种废纸（废新闻纸、废箱纸板、办公废纸、废书刊纸）纤维的表面形貌和结构特性;然后以聚乳酸（PLA）为基体、4种废纸纤维为增强体,利用注塑成形法制备废纸纤维/PLA生物可降解复合材料并探究废纸纤维对复合材料界面相容性和力学性能的影响。结果表明,废新闻纸纤维表面受损严重,多处出现扭结及横节纹;废箱纸板及废书刊纸纤维形态完整,扭结程度低且表面较为粗糙;办公废纸纤维长径比较大、细小纤维含量较少、纤维形态特性良好但表面相对光滑。废新闻纸/PLA复合材料和办公废纸/PLA复合材料的界面相容性较差,废纸纤维对PLA基体力学性能的增强效果一般;废箱纸板/PLA复合材料和废书刊纸/PLA复合材料的界面相容性较好,且废纸纤维有一定承力作用,对PLA基体弯曲性能和拉伸性能的改善效果较好。     

Inter-laboratories comparison at 100 GΩ and 1 TΩ level to evaluate the traceability transfer from INRIM in the field of high dc resistance

A National inter-laboratories comparison of dc resistance at 100 GΩ and 1 TΩ among the National Institute of Metrological Research (INRIM) and eight Secondary Electrical Calibration Laboratories was carried out in 2010. All the involved Laboratories made their measurements with a method based on a Multifunction Calibrator (MFC) and on a digital multimeter (DMM), both used in their dc voltage function.These and other Secondary Electrical Laboratories are traceable to National Standards by means of the calibration at INRIM of a complete set of primary standards or, alternatively, by means of the calibration of a high accuracy DMM or of a Multifunction Transfer Standard (MTS) or of few primary standards. All the relative differences between each Laboratory’s value and its reference value obtained in the comparison were within their relative expanded uncertainties. This result showed that the traceability transfer methods from INRIM to Electrical Secondary Laboratories lead to satisfactory results in the field of high dc resistance.     

Modified uncertainty estimation of antenna factor measurement by standard site method

The standard site method was used to measure antenna factor. Based on calculation of antenna factor uncertainty, ways of more precise estimation of uncertainty, leading to uncertainty reduction, are presented. Using uncertainty standards together with known approaches to radiated emission measurement uncertainty calculation, a model of antenna factor measurement and an equation for calculation of its uncertainty were derived. Possible steps to reduce resultant measurement uncertainty are described, including an analysis of correlation, and acknowledgment of frequency dependence. The uncertainty was calculated in 25 frequency points in the range from 30 MHz to 1000 MHz. Furthermore, various calculations of uncertainty are executed to examine the suggested effects on the uncertainty value.     

车载控制组合结构设计及应用

介绍了车载控制组合的结构设计的基本内容,详细分析了在机箱结构设计、热设计、电磁兼容性设计、防腐设计和环境可靠性试验等方面应该注意的问题,以及采取的相应有效措施.     

新型切削液工艺试验及推广应用

不同的冷却润滑材料在金属切削及加工的过程中冷却效果亦不同。为提高切削效率、工件的精度和降低工件表面粗糙度、延长刀具使用寿命,以达到最佳的经济效果,就必须减少刀具与工件、刀具与切屑之间的磨擦,并及时带走切削区内的废料。从企业实践中探讨分析了当代新型切削液在功能方面的优势及应用。