热连轧机带钢卷取温度影响因素仿真分析

针对带钢冷却特点,建立了带钢瞬态热传导仿真模型,采用有限差分法对1800mm热连轧机带钢终轧速度、带钢终轧温度、冷却水温度等因素对带钢层流冷却后温度的影响进行了仿真分析。得到的结果对于认识热轧带钢卷取温度的变化规律具有一定的应用价值。     

层流冷却条件下碳钢相变过程的数值模拟

 采用数值模拟的方法,结合宝钢2050热连轧层流冷却生产线,模拟研究了不同碳当量钢种在层流冷却条件下的奥氏体转变过程,计算了前段主冷、稀疏冷却、后段主冷3种冷却模式对奥氏体转变过程的影响,定量分析了带钢厚度方向不同部位处奥氏体转变的差别。结果表明:在所选定的工艺条件下,随着碳当量的增加,铁素体开始转变时间明显推迟,铁素体开始转变温度明显降低,而珠光体开始转变时间和温度变化不大;不同冷却模式下铁素体、珠光体各相开始转变时间及演变过程差别较大,但最终各相的体积分数接近一致;带钢厚度方向各部位由于冷却速度的不同而存在明显的组织不均匀性。     

层流冷却系统中动态修正设定计算

热连轧层流冷却系统中动态修正计算时，根据带钢样本上的实测参数进行实时计算，对冷却区中的各样本进行迭加计算，在设定计算的基础上通过微调集管组态，来及时消除带钢终轧温度、速度、厚度变化对卷取温度的影响，使卷取温度精度有所提高。     

珠江钢厂CSP热连轧层流冷却热过程模拟研究

分析了带钢层流冷却的传热过程，将相变潜热引入到层流冷却热过程数学模型，用过程模拟的方法研究了珠江钢厂CSP热连轧层流冷却系统。讨论了喷水方式、喷嘴位置、板速和板厚对带钢温度场分布的影响。结果表明建立的模型对于珠钢CSP热连轧层流冷却系统有较好的适应性，能够对实际生产起到较好的指导性作用。     

济钢1700mm热轧层流冷却系统改造

针对济钢1700mm热连轧生产线原层流冷却卷取温度控制系统中存在的不足和弊端,通过采用数学模型,开发多种冷却策略,修正带钢速度变化,抛钢后处理,采用反馈控制,开发模型维护工具等措施对层流冷去系统进行改造。系统改造后稳定可靠,卷取温度命中率有了较大幅度的提高。     

热轧带钢的冷却参数与翘曲关系

针对卷取温度为500℃的12 mm厚X70管线钢热轧带钢,利用MARC有限元软件建立层流冷却过程中的热-力-相变耦合的数学模型,计算两种下上冷却水比时层流冷却过程中温度场、应力、应变、相变体积分数和翘曲度随时间的变化.结果表明:1.25水比的冷却过程中,厚度方向上各面的冷却速度不一致,导致水冷前期带钢上下表面应变不同,带钢会产生向上的翘曲,冷却过程中边部最大的翘曲量达到21.84 mm;水冷后期带钢板形会逐渐恢复平直,但由于水冷过程中发生塑性变形,终冷时厚度方向上贝氏体含量的差异,卷取时带钢边部依然有-9 mm的翘曲量.上下表面的不均匀冷却是引起翘曲的根本原因.在保证X70管线钢性能条件下,采用1.58的下上水比工艺,卷取时边部翘曲量仅为-0.58 mm,合适的下上水比能大幅度减小层流冷却过程中带钢的横向翘曲.     

层流冷却过程中带钢温度场数值模拟

分析了带钢层流冷却过程中的传热，并利用有限元法对层流冷却过程中带钢温度场进行了模拟计算。结果表明：随着轧件厚度的减薄，在带钢厚度方向上的温差逐渐减小；冷却速度不同时，带钢表面温度和中心温度的变化趋势以及波动幅度相应发生变化。在进行模型计算时，应合理考虑带钢厚度及内部热传导的影响。这对提高数学模型的精度，控制卷取温度，提高产品质量以及指导生产具有重要意义。     

热轧带钢层流冷却过程温度场研究

 建立了热轧带钢层流冷却过程中温度场的三维有限元模型,对3 mm厚带钢轧后冷却过程带钢温度场进行模拟计算,得出卷取温度比现场测量值低9.5 ℃,相对误差为1.42%,验证了模型和假设的合理性。研究了上喷嘴直径对带钢温度的影响,带钢上表面宽度方向上存在2种不同的冷却区域：位于喷嘴正下方层流冷却过程中交替经过冲击区和平流区的区域和位于两喷嘴之间层流冷却过程中只经过平流区的区域,这造成带钢宽度方向上温度分布不均匀。计算结果表明,喷水量保持不变的情况下,存在一个最佳喷嘴直径,使带钢宽度方向上温度分布更均匀。喷水速度保持不变,增加喷嘴的直径有利于带钢宽度上方温度均匀,但增加了喷水量,降低了带钢的卷取温度。     

宝钢三热轧层流冷却过程控制系统研究与开发

热带钢轧制的卷取温度对带钢的质量有着重要作用.新建的三热轧层流冷却控制系统由宝钢自主开发,L2级进行完全动态控制(三菱L1级仅负责执行L2设定结果,不作任何动态控制).该系统具有实时控制性强、模型计算精度高、自学习后精度爬坡快等优点.相比2050mm产线,新增的冷却速率控制、带钢分段冷却、反馈PID模糊控制等技术,满足了高强钢和硅钢高品质冷却的要求.     

1780mm热连轧机带钢层流冷却自动控制系统开发及应用

层流冷却是控制带钢卷取温度的最重要手段。为了满足宁波钢铁有限公司1 780 mm热连轧机薄板生产线层流冷却工艺的控制要求,采用了由基础自动化控制系统和过程控制系统组成的两级计算机控制系统。介绍了层流冷却系统设备及自动控制系统结构。重点阐述了层流冷却基础自动化系统主要功能,包括层流冷却区域内带钢微跟踪、步序控制、卷取温度反馈控制以及速度前馈控制。运行结果表明,系统控制精度、响应速度均满足工艺要求。自系统投入运行以来,工作稳定,控制效果较好。     

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)     

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.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.