二滩工程砼拱坝采用新技术介绍

二滩工程砼拱坝建设过程采用一些新技术，使工程建设在保证质量的前提下，既赢得了工期，又降低了工程造价，从而使工程投资控制在总概算内并提前近９个月投产发电。     

土木工程结构健康监测、诊断以及安全评定技术

1.健康监测及诊断技术的基本概念 (1)安全性评估。通过各种可能的、结构允许的测试手段,测试其当前的工作状态,并与其临界失效的状态加以比较,评价其安全等级。对于不同结构,其重要程度不同,安全等级应该有所差别。安全性评估与可靠性不同,可靠性为一种概     

Effect of second phase precipitation behavior on mechanical properties of casting Al-Cu alloys

The effect of the second phase precipitation behavior on the mechanical properties and fracture behavior of the modified casting Al-Cu alloys was investigated. The tensile strength of the alloys increases firstly and then decreases due to the appearance of θ＇ precipitation phases, which increases firstly and then become coarser with the aging time increasing from 10 h to 20 h at 155 ℃. The strength of the alloys reaches the peak, resulting from ,Ω and θ＇ precipitation phases, and decreases due to ,Ω phases becoming coarser and θ＇ precipitation decreasing with the aging time increasing from 10 h to 20 h at 165 ℃. ,θ phase becoming coarser and θ＇ precipitation decreasing result in the strength of the alloys drastically decreasing after aging at 175 ℃ for 20 h. The ductility remains high level with increasing aging time at 155 ℃. The ductility irregularly changes as aging time prolongs at 165 ℃. The ductility is very low and at the same time gradually decreases with increasing aging time at 175 ℃. The Al-Cu alloy with a promising combination of tensile strength and ductility of about 474 MPa and 12.0% after aging at 165℃ for 10 h is due to a dense, uniform distribution of,Ω precipitation phases together with a heterogeneous distribution of θ＇ precipitations.     

Effect of Cu-Ti-C reaction composition on reinforcing particles size of TiC<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/Cu composites

TiC _x /Cu composites were fabricated by combustion synthesis and hot press technology. Using XRD, SEM, EDS, FESEM analysis methods, the effects of various carbon sources and different Cu contents on the microstructures of TiC _x /Cu composites and the size of TiC _x particles were investigated. Results showed that TiC _x reinforcing particles size increases with decreasing Cu content in Cu-Ti-C reaction system. With carbon nanotubes (carbon black) serving as carbon source, the generated TiC _x particles size transits from nanometer to submicron when Cu content corresponding to the reaction system is reduced to 60 vol% (70 vol%); while graphite serves as carbon source, there is no clear limiting concentration. C particles with smaller size, larger specific surface area and better distribution result in finer TiC _x particles, which is more beneficial to generating nano-sized TiC _x /Cu composites.     

氮碳薄膜反应溅射沉积过程的OES诊断

氮碳薄膜反应溅射沉积过程的ＯＥＳ诊断赵菁，王金国，康宁，王荣瑶，徐积仁（中国科学院物理研究所光物理实验室北京１０００８０）等离子体光发射谱（ＯＥＳ）作为一种实验的手段常用于等离子体薄膜沉积过程中气相物种及化学反应过程的诊断，它有助于对薄膜生长机理的了...     

情缘

你，钟情撤榄绿，身着橄榄绿，这的确是一种情缘。你“哇”的一声脱离母体时．你的爸爸正在奋战火魔。你到世的第三日，你那没有了眉毛的父亲才拖着疲惫的身子带着一张烤黑的脸和一头参差不齐的头发回来。你的妈妈心疼地哭了，可你的爸爸却笑得很甜……     

SiH4激光等离子体内H谱线的线型研究

本文利用OMA-Ⅲ系统测量了脉冲TEA CO_2激光诱发的SiH_4等离子体发光谱内H巴耳末系的H_α、H_β和H_γ线的线型及线宽。通过理论及实验分析,认为这些谱线的主要加宽机制为Stark加宽。由实验线型和理论线型的拟合得到等离子体的电子温度T≈40000K和电子密度N≈10~(17)cm~(-3)。