重复熔铸对ZLl04力学性能和组织的影响

为解决实验中ZLl04铝合金循环再利用问题,实验研究了ZLl04在相同浇注条件下重复熔铸时力学性能和组织的变化情况,并对铸件凝固过程的温度变化建立温度场模型．结果表明,温度场模型对于分析铸造过程的缺陷也有较大的指导意义．     

热连轧过程中温度场的模拟

考虑不同阶段各种因素对轧件温度的影响,采用有限差分法计算温度场,建立了带钢连轧生产过程轧件温度变化预报模型.其中,轧件应力应变采用Orowan公式计算,并引入迭代程序考虑轧件变形与温度变化间的相互影响.用此模型对某钢厂热轧板带生产过程中的温度场变化进行了解析计算,其预报值与实测值吻合较好.     

高速线材轧制过程的温度场分析

采用有限单元法求解了线材轧制过程中的温度场 .给出了轧件在圆 -椭圆孔型中温度场计算的处理方法 ,讨论了轧制功率对温度变化的影响 .得到了轧制过程中的温降曲线及横断面上温度分布的等值线 .模型计算结果与现场实测结果基本一致     

激光焊接1Cr17铁素体不锈钢温度场数值模拟

采用SYSWELD有限元软件,建立了激光焊接铁素体不锈钢的3D有限元模型.考虑材料的热物性参数与温度的非线性关系以及表面对流和辐射热交换的影响,分析了激光焊接过程中温度场的分布及焊缝表面不同点的热循环变化,并进行了实验验证.结果 表明:焊接一段时间后,焊接温度场呈现准稳定状态,随焊接热源的继续移动,焊缝区各点的温度基本保持稳定.沿着焊接方向,焊缝表面不同节点Tmax-T800和T800-T300冷却速度逐渐降低.另外,焊缝熔池的模拟结果和相同工艺参数的实验结果相吻合,证明了焊接过程中数学模型建立的合理性,模拟结果为铁素体不锈钢焊接过程的优化提供了理论依据.     

Ag/La2NiO4基电触头使用中温度场的有限元分析和实验研究

通过对电触头使用过程中闭合电弧→接触电阻焦耳热→分断电弧→自然冷却过程的分析, 建立了一个可描述电触头使用过程中, 瞬态温度场的统一计算模型.通过对Ag/La2NiO4基电触头的电接触实验机和相关实验的测试、分析和计算, 得到进行该电触头使用中瞬态温度场计算所需的基本参数.在此基础上, 采用有限元方法进行了计算, 得到了该电触头的瞬态温度场的分布和演化特点.通过将计算结果与相关的实验测量结果进行分析和比较, 可以发现瞬态温度场对于Ag/La2NiO4基电触头材料的侵蚀机制、使用寿命的研究具有重要参考价值.     

钛基非晶合金电子束焊接热力耦合模拟及非晶化

根据电子束焊接焊缝形貌特征及其深宽比大等特点,选用复合热源作为热源模型.通过线性插值等方式估计材料热力学参数随温度变化,模拟Ti基非晶合金电子束焊接温度场.模拟结果与实际焊缝取得良好的吻合,验证了热源模型的准确性.获得一定变量参数下电子束焊接钛基非晶合金温度场及热循环曲线.在温度场的基础上再进行焊接应力场的模拟,获得残余应力分布曲线.实验验证整个焊件没有晶化相析出,验证了该焊接工艺的可行性.      

还原法生产汽车发动机缸体用RE-ZL104合金

轻型汽车发动机缸体多采用 ZL104合金铸造(Al-Si 共晶合金)。本工作采用稀土化合物为原料,以碱金属氟化物和氯化物混盐为熔剂,改变稀土原料中稀土的存在状态和降低体系的初晶点及改善熔体的物理化学性质,以液态铝为还原剂,在熔铝炉内熔化铝过程中直接制备 RE-ZL104合金(RE 代表混合稀土金属)。RE-ZL104合金用于铸造汽车发动机缸体与 ZL104合金比较有如下优点:1.合金晶粒明显细化,合金中硅分布较均匀,富集点少;2.材料的强度和硬度可提高10%左右;3.由于微量稀土元素可以使铝液的表面张力降低,因此填充性好,铸造性能好。通过铸造1060台发动机缸体使用表明,铸件气孔,针孔减少,铸件成品率可提高5～10%。     

铝合金超厚板热轧过程温度场模拟

根据热模拟试验所获得的实验数据,在MARC软件中建立试验铝合金的材料数据库。采用二维弹塑性大变形有限元法,对铝合金超厚板热轧过程进行了数值模拟,分析了热轧过程中轧件温度场的分布和变化规律。模拟结果表明,在整个轧制过程中,轧件内部节点的温度变化缓慢,而表面节点的温度变化较为剧烈。计算的板坯表面温度与实测的表面温度吻合较好,表明该模型可以用来模拟中厚板轧制过程中的温度变化。     

热轧板坯加热工艺优化

建立了三段步进梁式加热炉板坯加热过程数学模型,用全隐式有限差分法对数学模型进行离散化,开发了板坯温度场计算模型.采用该模型重点研究了板坯宽度对板坯中心温度变化过程的影响规律.研究结果表明,对于厚度为200 mm的板坯,当板坯宽度大于600 mm时,板坯中心温度变化过程与板坯宽度无关.以此为根据,优化了板坯加热工艺,达到了提高生产效率并节能减排的目的.     

加热炉板坯断面温差数值模拟研究

采用有限容积法 (FVM),建立了四段步进梁式加热炉板坯加热过程的数学模型,通过编程模拟了板坯内部的温度场,并与黑匣子实验数据进行对比,验证了模型计算结果的可靠性.以Q235板坯为研究对象,模拟了板坯最大断面温差随板坯入炉温度的变化规律.并在板坯厚度相同的情况下,讨论了宽度变化对板坯出炉温度的影响,发现当宽度达到一定值时,板坯出炉的冷点温度和最高温度不再随宽度变化.     

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。     

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。     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results.     

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.     

参与式农业基地建设行动方案设计

为了编制实用性强的基地建设行动方案,首先,确定参与式发展的主体,搭建一个"决策框架";其次,针对行动目标,提出不同参与主体,如管理者、农民、消费者等团队与个人的目标及行动内容;最后,工作应向重塑伙伴式合作关系,挖掘农民自我发展潜力,完成三大角色的转换,打造农业基地文化等方向推进.