基于元胞自动机有限元法对方坯凝固组织的数值模拟

 基于元胞自动机有限单元法(CAFE)对国内某钢厂220mm×220mm方坯的三维显微凝固组织进行模拟,分析了CAFE法模拟凝固过程显微组织的物理本质,对形核密度、枝晶尖端生长动力学、枝晶生长的择优取向以及FE与CA耦合的实现分别进行了探讨。用该方法对方坯的三维显微组织进行模拟,并对结晶器出口处方坯的角部温度、中心表面温度及坯壳厚度进行了计算。模拟结果表明：当拉速为0. 85m/min,浇铸温度为1535℃,浇钢过热度为30℃时,结晶器出口处方坯角部温度在850~950℃之间,中心表面温度在1050~1170℃之间,坯壳厚度在15mm左右,铸坯柱状晶发达,等轴晶比率较小。模拟的铸坯组织的等轴晶比例与低倍试验结果吻合较好,可以很好地预测方坯实际凝固组织。     

连铸钢水过热度对大方坯凝固的影响

结合现场研究,利用显式有限差分法计算出不同工艺条件下的铸坯凝固情况;进行了过热度对出结晶器坯壳厚度、方坯表面温度、铸坯凝固过程中坯壳厚度和液相穴的影响的模拟分析研究。模拟结果表明：在拉速相同的情况下,随过热度的增加,出结晶器坯壳厚度减小、表面温度略微增加、铸坯液相穴拉长、坯壳减薄。     

连铸坯凝固传热数学模型的研究与应用

以安阳永兴钢铁公司1#方坯连铸机为研究对象，建立连铸坯凝固传热数学模型。研究了不同拉速、过热度及二冷比水量对铸坯表面中心和角部温度及铸坯凝固终点位置的影响。并对铸坯表面温度进行了实测，实测结果与模型计算基本吻合。与现场生产实际结合，优化二次冷却制度，铸坯质量得到明显提高。     

基于Deform-3D软件对AISI4340钢Φ600mm铸坯开坯工艺参数的模拟数值

利用Deform-3D软件对AISI4340钢Φ600 mm铸坯至300 mm × 300 mm坯的开坯过程工艺参数进行了数值模拟.通过对加热温度、轧制速度、压下率、2道次压下对铸坯心部变形和材料流动影响的研究,分析了开坯成形过程中心部等效应力和材料变形特点,获得了Φ600圆连铸坯开坯成300 mm方坯的成形规律.结果...     

70钢小方坯凝固过程数值模拟研究

为控制线材轧制用连铸小方坯质量,应用数值模拟软件对鞍钢股份有限公司炼钢总厂120 mm×120 mm小方坯连铸凝固过程进行模拟。模拟结果表明,在合理的冷却制度下,过热度低于35℃,拉速约为3.0 m/min的条件下,可以将结晶器出口坯壳厚度、铸坯液芯长度和铸坯表面温度控制在合适的范围内,并防止铸坯表面及内部产生缺陷、保证浇铸安全。     

方坯表面纵裂的数值模拟研究

针对ER80-G钢165 mm×165 mm方坯纵裂问题,基于连铸坯壳应力遗传特性,采用有限元软件ANSYS建立二维方坯热力耦合分析模型,对结晶器锥度进行了优化分析。结果表明:原结晶器锥度小,导致"热点"区域坯壳生长减缓;保护渣转折温度高,加剧了气隙影响。原结晶器角部区域最大气隙1.46 mm,坯壳表面温度最高差值130℃,"热点"区域比表面中心坯壳厚度减薄1.5 mm。通过锥度优化消除了热点现象,结晶器出口处距角部15 mm区域坯壳厚度由12.3 mm增加到19 mm;同时将保护渣转折温度由1 200℃调整到了1 050～1 100℃,促进坯壳与结晶器之间的润滑,裂纹发生率由2%下降到0.46%。     

Φ500mm轧机使用200mm×200mm连铸方坯的工艺探讨

通过对攀钢集团长城特钢股份有限公司二轧厂四车间基本情况介绍,通过对加热炉、用坯情况进行分析,同时通过相关假设,用艾克隆德等公式对采用200mm×200mm方坯生产2Cr13、45、40Cr等钢种时轧制力、轧辊强度进行了校核及分析,对采用200mm×200mm方坯的生产效率也进行了比较分析.最后得出如果在二轧厂四车间实现吃200mm×200mm方连铸坯的方案,可能得不偿失.     

20CrMnTi钢160 mm×160 mm方坯内部质量控制

针对20CrMnTi连铸160 mmX 160 mm方坯严重的内部质量问题,开展结晶器电磁搅拌(M-EMS)与凝固末端电磁搅拌(F-EMS)参数协同优化试验,通过方坯凝固组织检测和碳偏析检测,详细分析电磁搅拌参数对方坯内部质量的影响规律.此外,借助红外热成像仪检测方坯表面温度,进而利用ANSYS 软件预测方坯凝固传热过...     

厚板坯连铸二次冷却传热数学模拟

在考虑二冷边界换热的条件下,建立了与厚板坯连铸机相适应的传热数学模型。用远红外测温仪测试X65管线钢230 mm×1650 mm铸坯表面温度,实验结果同模拟结果吻合较好。应用数学模型,对不同拉速下管线钢的连铸凝固过程进行了仿真计算,分析了拉速对出结晶器坯壳厚度、铸坯表面温度和液芯长度的影响,得出在给定的二冷条件下,为得到合理的铸坯表面温度,管线钢的拉速应为0.9～1.2m/min。     

连铸坯中心偏析对LX72A钢帘线合股断丝的影响

70 t BOF-LF-Φ380 mm CC-开坯成150 mm×150 mm方坯-CR和200 t BOF-LF-200 mm×200mm CC-CR两种工艺路线所生产的Φ5.5 mm盘条经拉拔成Φ0.22 mm钢帘线合股过程的断丝率为Φ380mm圆铸坯工艺-2.86次/t,200 mm×200 mm方坯工艺-<1次/t。检验结果表明,圆坯工艺生产的盘条严重的中心偏析是大量断丝的主要因素,150mm×150 mm轧坯的宏观碳偏析高达1.11。采用断面尺寸200 mm×200 mm以上的方坯连铸工艺流程,中间包钢水过热度15～25℃,拉速恒定,采用结晶器和末端电磁搅拌,可有效地减轻中心偏析。     

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.     

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.     

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。     

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.