平三角-圆孔型钛合金棒材轧制过程的三维有限元模拟及应用

采用有限元软件ANSYS/LS-DYNA对三辊Y型轧机平三角-圆孔型系统轧制钛合金(TC4)棒材工艺进行模拟,研究了棒材在平三角-圆孔型中的金属流动、应力应变、轧制力等轧制参数。模拟结果表明:采用平三角-圆孔型系统生产钛合金棒材是可行的,为新产品轧制方案及孔型设计提供了分析依据。     

袖珍pc—1500型计算机在岩体应力测量数据处理中的应用

本文主要介绍便携式PC-1500型计算机在矿山岩体应力测量复杂数据处理中的应用。目前国内进行岩体应力测量的单位普遍使用微、中型机进行数据处理。但由于矿山条件的限制,中、微型机难于在矿井等现场中推广。针对PC-1500机的功能和特点,结合现场数据测试的情况,我们试用PC-1500型计算机对岩体应力测量的数据进行处理,取得了满意的结果。     

H型钢辊式矫直过程残余应力理论研究

H型钢辊式矫直过程及矫直后的残余应力对其承载能力有很大影响,传统上以残余几何形态评价矫直效果存在一定不足.基于弹塑性理论,对辊式矫直过程中H型钢断面上弹性核高度和残余应力进行了理论研究,推导出了相关解析公式,结合实例计算及仿真,验证了解析公式的正确性,对现场工艺参数的制定提供了理论依据.     

深部硬岩可切割性及非爆机械化破岩实践

为了系统地认识应力条件、矿岩特性和破岩参数等因素对深部硬岩截割特性的影响,梳理并总结了以往关于深部硬岩截割特性室内试验及非爆机械化破岩现场实践工作。根据3种应力环境对镐型截齿静态和动静组合破岩特性的影响,结合构建的截齿破岩峰值载荷理论及回归模型,发现硬岩在较低围压或无围压条件下具有安全高效的破碎表现;根据高单轴围压下截齿破岩扰动诱发岩爆的过程和机理,揭示了采矿过程中由开采扰动诱发高应力矿柱岩爆的发生机制;基于加卸荷诱导损伤、预切槽和预钻孔等人为诱导缺陷对镐型截齿破岩特性的影响研究,得到人为诱导缺陷可有效提高硬岩的可切割性,获得了改善硬岩可切割性的成套方法;现场试验了多种机械化破岩方法,提出了基于应力解除和动静组合破岩的预切槽硬岩矿体旋转振动连续截割设备及其施工工艺。研究结果可为深部硬岩矿体非爆机械化规模开采提供理论基础和现场实践经验。     

5 000 mm宽厚板轧机支承辊新辊型

 结合5 000 mm轧机支承辊现有的几种辊型,按照接触应力均布原则提出了一种新的支承辊辊型曲线。利用ABAQUS有限元软件,通过改变轧制参数,进行三维轧制模拟计算,对比分析了新辊型和现有辊型支承辊的应力场、辊系变形以及板形情况,得到了最小接触应力分布辊型曲线;结合有限元分析应力结果,采用局部应力应变法,利用FE-SAFE疲劳分析软件对新辊型和现有辊型支承辊进行了疲劳寿命的估算,证明了新辊型可以有效地提高支承辊的使用寿命。     

大型炼钢厂加料跨行车梁安全性分析

针对炼钢厂加料跨行车梁整体框架结构,建立了三维有限元模型,并进行了危险工况下的力学仿真分析。首先采用UG建立三维几何模型,然后将几何模型导入Hypermesh并建立三维有限元模型,最后选择ANSYS中的静力学分析模块完成数值计算。结果显示,加料跨J列行车梁存在局部高应力区,其应力超过强度设计值。经过现场勘测,在与有限元预测的高应力区相对应的位置出现了开裂现象。勘测结果验证了数值分析准确可靠,所建模型成功预警了大型空间复杂结构的安全隐患,为结构设计与修复提供了理论依据。     

基于岩爆碎屑研究的高楼山隧道岩爆机理分析与类型判定

在建高楼山隧道是通达陇南市及四川省九寨沟的控制性工程,项目具有“三高一大”的特点,是复杂地质条件下深埋特长公路隧道的典型代表.以现场两种岩爆类型为研究对象,通过冲击岩爆实验系统并设定不同应力路径,首先进行了岩爆实验全过程分析,而后对比研究了板裂屈曲型岩爆实验碎屑(岩爆碎屑1)、爆破冲击型岩爆实验碎屑(岩爆碎屑2)和现场收集的不知类型的岩爆碎屑(岩爆碎屑3)的质量、尺度分布及形状分形维数特征.在此基础上,结合岩爆实验图像变化过程,深化了对不同类型岩爆碎屑成因及岩爆机理的认识.结果表明：(1)板裂屈曲型岩爆和爆破冲击型岩爆区别在于破坏主导机制不同,一种为张拉破坏主导,另一种为张剪破坏主导.(2)岩爆碎屑1以中粒、条板状碎屑为主,在长度方向上更容易破碎,且质量远大于岩爆碎屑2,这与竖向应力集中形成板裂化结构的板裂屈曲型岩爆孕育机制密不可分.(3)动载的介入使得岩爆碎屑2受剪切作用明显,因而在厚度方向的破碎更容易且破碎程度更高,形成以粗粒、片状碎屑为主的碎屑,该类型碎屑在现场岩爆中由于质量较大、体积较大、弹射距离较远,因此危害性可能更大.(4)通过上述比对分析,可基本判定岩爆碎屑3对应的岩爆类...     

转折型沟谷对地震崩塌体块石拦截效果分析

在现场调查和统计的基础上,分析了青川县东河口地震型崩塌体200余块块石沿转折型沟谷的分布特征和各不同体积组块石的分布特征.提出块石拦截率概念,并据此从数量和体积2个角度定量分析了沟谷拐弯段对块石的拦截效果.分析认为:转折型沟谷在控制块石的运移方面具有积极作用;相比小体积块石,沟谷拐弯段对大体积块石具有更好的拦截效果;从数量上来看,沟谷内靠近崩塌堆积体后壁的拐弯拦截块石相对较少.本文的分析思路及方法为认识和研究转折型构筑物及其拐弯在控制崩塌体运移等方面提供参考,所得结论为人类防治崩塌灾害等方面提供借鉴.     

空冷对Q235材质H型钢腹板热残余应力场的影响

研究了大规格H型钢产品矫后出现腹板波浪以及切割过程中出现腹板开裂的原因.采用有限元数值分析和现场测试相结合的方法,分析了H型钢空冷至矫直温度时残余应力的分布规律.结果表明,现有生产工艺条件下,型钢冷却至矫直温度(80℃)时,腹板上存在着较大的压应力,致使发生腹板波浪.在腹板和R角的交接部位,残余应力分布极为不均,由压应力向拉应力突变,是导致产品切割开裂的主要原因之一.     

金相复型技术在压力容器定期检验中的应用

金相复型是一种无损金相分析技术,在承压类设备的定期检验中发挥着重要作用。阐述了金相复型技术的原理,详细地介绍了现场金相复型过程的操作方法,并结合模拟实验阐述了金相复型技术在现场压力容器定期检验中的应用,提出了金相复型过程中要注意的问题及应用前景。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.