直流电弧炉炉底阳极用耐火材料

介绍了直流电弧炉目前流行的导电炉底型、多支接触钢钎型、钢片散热型和水冷钢棒型4种类型的炉底阳极用耐火材料的设计理念和应用情况,并着重剖析了水冷钢棒型炉底阳极用耐火材料的组成结构、理化性能和应用特点,同时还介绍了宝钢150 t超高功率直流电弧炉水冷钢棒型炉底阳极耐火材料的使用状况,指出存在的缺陷并提出改进的方向:改善炉底阳极套筒砖的高温强度和热震稳定性将是提高炉底阳极套筒砖寿命的关键,改善镁钙质干式炉底捣打料的高温收缩和高温耐蚀性将是提高炉底捣打料寿命的关键.     

直流电弧炉钢棒式底电极传热与流动数学模型

 为了深入了解直流电弧炉水冷钢棒式底电极的传热过程，根据底电极的炉底结构结合相应的边界条件，建立了基于流动的二维轴对称固液相变传热数学模型。推导了考虑水冷铜套和电极之间空气隙影响的等效对流换热系数以及通电时的径向和轴向电磁力方程。模型中考虑了底电极从固态300 K到液态2 000 K过程中钢的物性的连续变化。利用所建模型，可以数值模拟直流电弧炉单炉冶炼、双炉冶炼的非稳态传热过程以及考察计算参数和结构改变影响的稳态传热过程，为改善电弧炉的安全性、提高工作效率提供理论依据。     

电弧可控直流电弧炉的开发

在建的电弧炉中大约７０％－７５％是直流电弧炉。它的主要优点是能耗低、电极消耗低、而且闪炼问题比较少，Ｕｓｉｎｏｒ／Ｓａｃｉｌｏｒ开发了一种由水冷钢棒组成的底电极，这种底电极已经应用于由Ｃｌｅｃｉｍ建造的直流电弧炉上，多根底电极的单独配置可以控制电弧的位置，因此使熔炼过程比较均匀，闭环电流分配系统可避免熔炼过程中出现冷点和热点。     

直流电弧炉技术发展概况

1发展概况率先研究和开发直流电弧炉技术的是瑞典ABB公司、法国钢铁研究院（IRSID）和德国MAN—GHH集团：ABB公司在解决了大功率整流装置和导电耐火材料技术难题后，于70年代末在瑞典钢铁公司杜姆纳尔沃厂建了一座30t直流电弧炉，并于1980年10月在美国获得专利。法国钢铁研究院在80年代初进行了一系列研究工作，开发了埋入式水冷钢棒底电极系统，并与法国Clecim公司联合为法国齐诺尔萨西洛尔公司提供了75t直流电弧炉。德国MAN—GHH公司则于80年代中期开发出埋入式空冷钢棒底电极技术，并在施罗曼－西马克公司Kerenztal厂和美国钮…     

提高直流电弧炉炉底使用寿命的工艺实践

对水冷钢棒式底阳极的直流电弧炉进行加高炉底改进,通过节电工艺应用,降低送电时间,使炉底、炉壁的使用寿命同步,提高炉龄。     

超高功率直流电弧炉水冷钢棒型底电极冷态接长技术的研究

主要介绍了超高功率直流电弧炉水冷钢棒型底电极冷态接长技术，通过采用该技术以延长炉底寿命，从而达到充分利用炉底耐材、提高炉龄，减少炉修时间、提高产能，降本增效的目的。     

杭钢电炉底电极改造及应用实践

针对杭钢电炉底电极存在的问题，通过各类底电极的对比，将原水冷钢棒底电极改造为钢片式底电极，取得了较好的效果。     

直流电弧炉偏弧控制的研究

８０年代以来,直流电弧炉炼钢技术得到很大发展,并且呈现取代交流电弧炉的趋势。但在高功率直流电弧炉中,直流电弧的偏弧问题给其运行带来很大危害。直流电弧炉的偏弧现象是由电弧炉内电磁场的分布情况决定的,针对底电极为４根水冷钢棒的直流电弧炉,本文提出了电弧位置闭环自动控制的方法。首先在三维导体布置下建立直流电弧的偏弧模型。直流电弧在炉体内受到的使其产生偏移的电磁力为Ｆ磁＝∫ＺｔＺｃｄＺ‰ＳｊＺ×ΣＮｋ＝１Ｂｋｄｓ式中　Ｚｔ———石墨电极端头的Ｚ轴坐标值;Ｚｃ———钢水液面的Ｚ轴坐标值;ｓ———电弧柱的截…     

直流电弧炉底电极的设计与应用

本文由电工学、传热学及触针风冷底电极特点，推导出触针底电极根数、直径与最大直流电流的关系式，结合上钢五厂１０ｔ直流电弧炉底电极的设计，说明关系式的应用、注意事项以及底电极冷却所需气体量的确定等。底电极尺寸确定过程虽然是以触针风冷底电极为例，但同样适合于棒式水冷电极尺寸的确定。     

直流电弧炉底电极的结构型式

世界上直流电弧炉的发展异常迅猛,我国也开始了直流电弧炉的建设。直流电弧炉与交流电弧炉的最大差别,除供电系统多一套可控硅整流装置外,电炉本身的不同就只有炉底结构的区别了,不同的直流电弧炉的形式也是指炉底电极的型式,本文主要介绍底电极的型式。     

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.