液压缸差动回路特性分析与计算

本文论述了液压缸差动回路的压力、流量、速度和效率特性。推导了其相应的数学表达式,并用实例分别计算了这些特性。     

Nanoengineering of Flux Pinning Sites in High-Tc Superconductors

Volume pinning forces were determined for a variety of bulk high-Tc superconductors of the 123-type from magnetization measurements. By means of scaling of the pinning forces, the acting pinning mechanisms in various temperature ranges were identified. The Nd-based superconductors and some YBCO crystals exhibited a dominating pinning of the δTc-type (i.e. , small, superconducting pinning sites). In contrast to this, the addition of insulating 211 particles provided pinning of the δ/-type; providing effective pinning in the entire temperature range acting as a "background" pinning mechanism for the peak effect. Due to the small coherence lengths of the high-Tc compounds, effective pinning sites are defects or particles of nanometer size relative to ζ3. Integral magnetic measurements of the magnetization as a function of temperature in large applied magnetic fields (up to 7 T) revealed that practically all high-Tc compounds were spatially inhomogeneous, which could be caused by oxygen deficiency (YBCO)     

自净化油箱在液压润滑系统中的应用

介绍了液压润滑系统污染控制的重要性，根据液压润滑系统中的污染平衡与链式反应，分析了液压润滑系统传统污染净化模式的缺点，提出自净化油箱和全流量回油过滤技术的概念，并说明了它在液压润滑系统中的应用。     

印制电路板免清洗技术研究

文章针对传统焊接工艺中由于助焊剂对环境的污染，旧的焊接工艺将被淘汰，免清洗技术中使用了低固态含量的助焊剂，可以免于清洗，工艺先进，符合环保要求。     

银幕照度及投影器有效光通量测定的误差分析与数值修正

通过对九孔板成象中心亮斑光能量的分析与计算，给出用九孔板测量银幕照度及投影器有效光通量数值的修正方法。     

确定采空区合理瓦斯抽放流量的数值模拟

用有限元数值模拟方法结合图形显示技术,对铁法小青矿 S_2403采空区瓦斯抽放问题进行了分析,模拟了采空区瓦斯分布、回风隅角瓦斯聚积以及瓦斯抽放的流体力学原理,重点探讨了利用数值模拟方法解决抽放流量的合理确定问题:抽放瓦斯可降低通风强度,并能控制采空区瓦斯向工作面涌出;理论上还可进一步改进抽放工艺为单纯埋管抽放方式,适当提高抽放流量,以达到安全、经济的目的。     

海洋环流数值模式中的若干技术问题评述

详细介绍了当前国内外海洋环流数值模式中垂直涡动粘性系数、海表面动量、热量和质量通量的参数化方案以及开边界条件的选取等技术问题，评价了各种方案和技术的优缺点，为海洋环流数值模式的研制和改进工作提供了参考依据。