承钢连铸中间包水口粘结原因及改进

介绍了承钢SPHC铝镇静钢的生产工艺,分析了低碳铝镇静钢浇铸过程中间包水口粘结现象的原因,并分别针对温度和Al_2O_3引起的低温絮流制定了相应的改进措施。实施后,连铸水口絮流现象得到有效解决,大于30μm的Al_2O_3夹杂基本去除,连铸机生产稳定、正常。     

管线钢X65连铸过程絮流原因分析

通过对低碳低硫低氧铝镇静钢X65连铸过程絮流原因的分析,得出引起塞棒絮流的原因是高Ca的钙铝酸盐粘附在塞棒头部。浇注初期,塞棒头部吸热使周围钢液温度急剧下降,析出高熔点钙铝酸盐被粘附在塞棒头部,引起塞棒曲线上行。另外,通过热力学计算,在低碳低硫低氧铝镇静钢X65中,1 540℃时,形成12CaO·7Al₂O₃需要的w[Ca]为16×10^-6,过量的Ca进一步反应形成高熔点钙铝酸盐。在中间包工作层、塞棒、水口、碗口等与钢水接触部位全部使用镁质耐材的条件下,在低碳低硫低氧的铝镇静钢生产时,向钢液中喂入的Ca含量越多,塞棒上行程度越严重。采用高碱度渣系和Al降低钢中的O和S,将Ca喂入量控制在0.065 0～0.071 5 kg/t,中间包w[Ca]控制在(10～15)×10^-6,可以有效控制塞棒絮流。     

钙处理技术在鞍钢ASP生产线的应用

针对鞍钢股份有限公炼钢总厂四工区连铸生产铝镇静钢钙处理钢水口堵塞问题,采取了氧化性顶渣改质、控制顶渣干稀程度以及控制钙处理钢水的钙含量和喂线速度等一系列措施,取得了良好的效果,连铸因絮流断浇的次数从平均每月1次降低到3个月1次。     

薄板低碳铝镇静钢生产工艺的优化

介绍了本钢炼钢厂LF炉精炼低碳铝镇静钢时,为避免薄板坯连铸机浇铸过程中的水口絮流问题,进行了工艺优化。通过工艺优化,保证了钢包顶渣的改质效果,达到了最大程度去除夹杂物以及使残余夹杂物充分变性处理的目的,从而提高了钢水的洁净度和可浇性,有效避免了在薄板铸机浇铸过程中的开口度上涨现象。     

包钢小方坯连铸过程中的水口堵塞

中间包浸入式水口的堵塞是铝镇静钢连铸过程中普遍存在的问题,对于小方坯来说,问题尤为严重.包钢炼钢厂采用80 t转炉,钢包精炼炉(LF炉)和六流小方坯连铸机生产铝镇静钢.针对浸入式水口堵塞的问题,通过对LF炉精炼过程的优化,改善了钢水的浇铸性能,保证了小方坯铸机的顺利生产.     

铝铁合金在在转炉炼钢中的应用

介绍韶钢用铝铁合金脱氧合金化生产低碳铝镇静钢的工艺.采用铝铁脱氧合金化后,低碳铝镇静钢的炼成率从原工艺的93%提高到99%以上,并且轧材的质量有了大幅度的提高.     

LF炉外精炼钙处理的工艺理论与实践

通常在冶炼低合金铝镇静钢时,由于在连铸过程中易发生钢水二次氧化,致使钢液中形成氧化铝内生夹杂,严重时可造成中包水口堵塞.目前在生产铝镇静钢时,一般采用在LF炉精炼后期进行钙处理去除氧化铝夹杂,并通过控制钢水中钙铝酸盐的形态来改善钢水的流动性和可浇铸性.本文介绍了铝镇静钢的生产工艺流程,结合夹杂物形态改变的原理对铝镇静钢...     

铝锰铁合金在低碳铝镇静钢中的应用

介绍了韶钢用铝锰铁合金脱氧合金化生产低碳铝镇静钢的工艺,采用铝锰铁脱氧合金后,低碳铝镇静钢的炼成率从原工艺的93%提高到99%以上,并且轧材的质量有了大幅度的提高.     

邢钢铝镇静钢工艺优化

介绍了铝镇静钢的生产工艺及主要设备,并对现有工艺进行了分析。针对铝镇静钢夹杂物数量不能满足市场需要,对铝镇静钢的生产工艺进行优化。实践证明,优化后产品质量满足了市场需要。     

用喷射液体铝的方法生产半镇静钢

美国钢公司的费尔利斯厂为提高半镇静钢的质量和降低钢的生产成本,开发了一种用喷射液体铝的方法生产半镇静钢的技术。其生产工艺为:当将冶炼的沸腾钢钢水浇铸到上小下大的钢锭模内到达绝热板的下方时,停止浇钢并使钢水在钢锭模内沸腾2～3min。而后在向钢锭模内补浇钢水的同时,向钢水铸流中喷射液体铝,使钢水脱氧停止沸腾而形成偏沸腾钢型的半镇静钢钢锭。喷射的液体铝量为0.3～0.4kg/t钢。所生产的半镇静钢用于轧制供深     

气泡法测量多孔材料孔径分布

本文描述了气泡法测量多孔材料孔径分布的实验方法和数据处理。并对不同数据处理方法进行了比较,指出了各种数据处理方法的优缺点。     

封闭管道流量的非接触式测量

在流体传动系统中，流量是需经常测量的过程参数之一。本文先指出了非接触法测流量的优越性，再基于各种物理原理，叙述了封闭管道流量的几种非接触测量方法与特点。     

Material Flow Analyses of Noncircular-Shaped Granular Media Using Discrete Element Methods

The mathematical development and application of two discrete element methods for analyzing the material flow of granular media is described. These two discrete element methods model the noncircular-shaped particles with analytical surface representations. 2D particles are modeled with a superquadric equation and 3D particles as ellipsoids. Two examples are then presented to illustrate the applicability of these techniques in engineering analysis. These examples include (1) flow of particulate media in a rotating drum; and (2) flow of ore material in an inclined ore pass system.     

氧化还原电位计在湿法冶炼中的应用

介绍了活性硫化镍除铜工业试验的工艺流程 ,氧化还原电位与除铜指标的关系 ,氧化还原电位计的工作原理 ,氧化还原电位计在试验中的应用情况及其应用中遇到的问题 ,并提出解决问题的方法。     

Doppler ultrasound investigation of uterine and ovarian blood flow in infertility and early pregnancy

This review describes the current use of Doppler ultrasound to examine blood flow in the uterus and ovaries in infertile patients and during early pregnancy. The basics of Doppler ultrasound and the different methods of measuring blood flow are discussed from the viewpoint of the clinician who may be unfamiliar with Doppler physics and terminology. Normal values in the menstrual cycle and the relationship of uterine and ovarian blood flow to infertility and to implantation following in-vitro fertilization are presented. Normal values for uterine blood flow in the first 16 weeks of pregnancy and the effect of sex steroids and ovulation induction on their values are described. The possible relationship of defective uterine blood flow to recurrent abortion is examined. New areas of investigation, such as the effect of standing on blood flow, and the effect of drugs are explored. The findings of this review indicate that Doppler blood flow studies may provide significant information about possible causes of some disorders of infertility and early pregnancy and methods of treatment for the same.     

冷连轧机组乳化液喷淋流场的数值计算与分析

针对冷连轧机组轧制过程中乳化液喷淋流场采用常规数值模拟方法计算精度较差无法满足工程需求的问题,在大量的现场试验与理论研究的基础上,充分考虑到冷连轧机组的生产工艺及设备特点,建立了相应的数学模型,运用计算流体动力学（CFD）的大型商用软件Fluent对乳化液喷射流场进行了数值计算和分析,给出了在喷射梁上的三个喷嘴与喷射梁垂直和成一定角度时的速度场、压力场分布情况,为喷射梁的设计和喷淋流场的优化奠定了坚实的理论基础。     

Preimplantation genetic diagnosis: current status and new developments

Preimplantation genetic diagnosis (PGD) is a very early form of prenatal diagnosis aimed at eliminating embryos carrying serious genetic diseases before implantation. To this end, two major technologies are in use: the polymerase chain reaction (PCR) for monogenic diseases and fluorescent in-situ hybridization (FISH) for chromosomal aberrations. In this review, a number of problems arising from the use of these technologies, as well as their possible solutions and new developments, are discussed. Concerning PCR, the phenomenon of allelic drop-out, as well as methods to reduce this problem, such as fluorescent PCR, are described. The advantages and disadvantages of sperm separation by flow cytometry as an adjunct to sex determination for the avoidance of X-linked disease are discussed. The application of FISH for aneuploidy detection is commented upon and the advances in cell recycling, in which PCR and FISH are combined, are analysed. Finally, diseases for which PGD is currently possible are summarized.     

The physical and mathematical modelling of the flow field in the mold region in continuous casting systems: Part II. The mathematical representation of the turbulent flow field

A mathematical representation is developed for the turbulent flow field, temperature field, and tracer distribution in the upper region of the liquid pool in continuous casting. The problem is formulated through the statement of the two-dimensional turbulent flow equa-tions, which were then solved numerically, using the adaptation of a technique described by Spalding and coworkers. The computed results for the velocity fields were found to be in good qualitative agreement with the results of water model studies for both straight and radial flow nozzles. Furthermore, the predictions based on the model for the temperature and tracer profiles within the pool seem to be consistent with expectations. R. T. YADOYA, formerly Graduate Student, State University of New York at Buffalo     

冶金企业生产计划的最大利润流算法

以节点表示原料、在制品或成品,以弧表示工序,运用网络流描述冶金企业生产流程,将冶金企业生产计划的优化问题转化为共享资源的最大利润流问题。提出了生产计划的网络优化算法,进行了复杂性分析,并给出一个计算实例。该算法的计算结果与单纯形法的结果完全相同,但求解过程较后者简洁。     

Internal iliac revascularization during aortic aneurysm replacement: a review and description of a useful technique

The coexistence of infrarenal aortic aneurysm and internal iliac artery aneurysm may represent a management problem with regard to preservation of the pelvic blood supply. In this article, we review the methods available for maintaining the pelvic blood flow and describe a useful technique that we have successfully utilized in seven patients to preserve the hypogastric artery blood flow.