配合煤选择性粉碎工艺的应用

介绍了配和煤选择性粉碎工艺的原理、特点及应用情况。结果表明该工艺投用后，配合煤质量明显改善。     

TC21合金高温渗氢组织变化的研究

研究了α＋β型钛合金TC21锻态组织的高温渗氢行为，通过对合金渗氢前后和除氢后的显微组织观察发现，渗氢后大β相的数量明显增加，并有氢化物的生成；除氢后，晶粒组织得到细化，原始晶界变得模糊，其相应的硬度也发生了一定变化。分析了氢致组织细化的机理。     

T122耐热钢平衡相转变的热力学计算和分析

采用Thermc-Calc热力学计算软件，对820～1200℃时T122高铬耐热钢（％：0．11～0．12C，11．37～11．97Cr，1．90～1．93W，0．38Mo，0．86～0．90Cu，0．05Nb，0．19～0．20V，0．58～0．67N，0，0023～0．0028B）在820～1200℃的热力学平衡相及合金元素Cr、Al、Ti对6铁素体和主要析出相的影响进行了研究。结果表明，T122耐热钢残留有较多的6铁素体，其主要析出相为M23C6、Laves和MX。在950～1050℃时6铁素体最少，其含量为15．7％～18．9％。M23C6析出开始温度为940℃，Laves相为750℃，MX则较稳定为〉1250℃。Cr对δ铁素体含量影响很大，但对析出相影响较小。降低Al、Ti有助于降低δ铁素体含量，增加MX含量。     

数字矿山及其关键技术探讨

“数字矿山”是实时管理和调度矿山全部信息资源、人力资源、生产要素和生产经营活动的巨型信息系统,可分为中央控制系统、生产信息处理系统、综合监测监控信息系统、网络通信保障系统等4大部分。构建数字矿山的核心技术包括数据采集和高速网络传输技术、分布式空间数据库和网络GIS技术、空间数据仓库和空间数据挖掘技术、三维可视化和虚拟现实技术、动态模拟和人工智能技术。     

制备工艺对碳纤维增强碳化硅基复合材料结构和力学性能的影响

以化学气相沉积碳为界面层,聚碳硅烷为先驱体,经过10个周期的浸渍-裂解制备了三维编织碳纤维增强碳化硅复合材料(3D-Cf/SiC)。考察了碳涂层高温预处理和陶瓷先驱体第一个周期1600℃裂解对复合材料结构与性能的影响。结果表明:碳涂层高温预处理有助于复合材料密度的提高,弱化了复合材料的界面结合,从而显著提高了复合材料的力学性能,复合材料弯曲强度达到571 MPa,剪切强度51 MPa,断裂韧性18 MPa.m1/2。     

铁水罐再加热技术研究

分析了铁水温降的构成和主要原因 ,提出了解决措施。在对铁水罐烘烤时间和最终效果进行分析计算的基础上选定了烘烤位置。通过比较几种烘烤方案的特点 ,提出了采用高炉煤气蓄热式烘烤铁水罐。     

Effects of short cracks produced at blunted pre-crack tip on stress and strain distributions

The present work investigates problems: (1) How are the plastic strain and the stress (triaxiality) re-distributed after a short crack initiated, extended and blunted at the pre-crack tip? (2) How do the above changes put a crucial effect on the triggering of the cleavage fracture? Based on the previous observations of configuration changes and fracture surfaces of pre-crack tips, Finite element method (FEM) simulations of a short crack initiated, extended and blunted at a pre-crack tip and calculations of distributions of stress, strain and triaxiality are carried out for 3PB pre-cracked HSLA steel specimens tested at -130^°C. The results reveal that: as long as the fatigue pre-crack is only blunted, in its vicinity a region where the accumulated strain is sufficient to nucleate a crack, and a region where the stress (triaxiality) is sufficient to propagate a crack nucleus are separated by a distance. The nucleated crack cannot be propagated and the cleavage fracture cannot be triggered. While a short crack produced at the fully blunted fatigue pre-crack, the strain retains, the stress (triaxiality) is rebuilt. An initiated and significantly extended and then blunted short crack makes a tip configuration, which on one hand is much sharper than that of the fully blunted original pre-crack tip, on other hand is wide enough to spread its effects into the high stress covered region. This sharpened crack tip configuration re-builds a ‘sharper’ distribution of stress (triaxiality) and makes two regions metioned above closer. Finally the two regions overlap each other and a cleavage crack can be initiated and propagated at a distance ahead of the blunted fatigue pre-crack.     

氮离子注入法合成CNx膜的化学键表征

采用N离子注入金刚石膜和热解石墨方法合成了CNx膜,用Raman光谱和XPS谱对合成薄膜中C、N的化学键合状态进行了研究.通过与Raman光谱的比较,我们对合成样品XPS谱中N1s的化学键合状态作出如下归属:≈400.0 eV属于sp2 C-N键;≈398.5 eV则属于sp3 C-N键.结果显示:碳原子、氮原子间的化学键合状态,明显地依赖于衬底材料及注入N离子的能量.     

Relative hazard rate estimation for right censored and left truncated data

In medical research differences among treatment groups are a common focus of study. The concept of relative hazard rate is a tool for comparing two groups in terms of their difference in risk rates. A kernel estimator is proposed in the case where both samples are subject to left truncation and right censoring and an iid representation is obtained in this setup. The asymptotic distribution and the asymptotic mean squared error of the estimator are obtained. An application to the famous Channing House data set illustrates the theory. Research supported in part by MCyT Grants PB98-0182-C02-01 and BFM2002-00265 (ERDF support included) and XUGA Grant PGIDT00PX110501 PN for the first author and by the Ministry of the Flemish Community (Project BIL00/28, International Scientific and Technological Cooperation) and by the IAP research network nr P5/24 of the Belgian State (Federal Office for Scientific, Technical and Cultural Affairs) for the last two authors.