连退过程带钢热瓢曲指数及其影响因素

 针对带钢连退过程中的热瓢曲问题,充分考虑到连退机组的设备与工艺特点,从内力、外力两方面因素分析了热瓢曲以及横向压应力的产生机理,阐述了热瓢曲的发生规律,首次提出了瓢曲指数的新概念,给出了相应的瓢曲临界条件,建立了一套适合于连退过程的带钢热瓢曲指数的计算模型,定量分析了不同工艺段内带钢瓢曲指数分布规律以及相同工艺段内来料板形、横向温差、炉辊辊型、摩擦因数、设定张力、通板速度等因素对带钢热瓢曲指数的影响,并将相关理论应用到生产实践,开发出了“连退机组通板过程带钢瓢曲预报软件”,实现了对连退过程带钢瓢曲的在线预报,为瓢曲缺陷的预防和控制奠定了坚实的理论基础。     

连退炉辊凸度控制技术在预防带钢瓢曲上的应用

通过对带钢在立式连续退火炉退火时出现的热瓢曲现象产生原因的分析,介绍了梅钢连续退火炉通过控制炉辊凸度预防连退炉内带钢瓢曲的方法。     

带钢连退热瓢曲与初始板形关系仿真与实践

连退炉内的带钢热瓢曲严重影响了生产线的顺行,给现场造成巨大的经济损失,为了有效缓解带钢的热瓢曲,从力学屈曲理论和有限元模拟技术对宽薄带钢在高温炉内的带钢热瓢曲进行了研究,结果表明:对于不同初始板形的带钢,其对应的临界瓢曲应力有明显的差异。通过酸轧目标板形的优化和修改,有效地把炉内带钢热瓢曲概率降低了50%以上。     

连续退火机组缓冷炉带钢瓢曲原因分析

针对宝钢某单元连续退火机组发生的薄板轻微热瓢曲问题,对影响退火炉带钢瓢曲因素进行了调查,并对板带截面试样进行金相分析,进而对带钢瓢曲缺陷与冷却段的相关性设计针对性生产试验,最终成功将带钢瓢曲缺陷的发生锁定在缓冷炉(SCF)的顶辊上。最后围绕顶辊的辊型和材质分析了带钢瓢曲缺陷产生的原因,并对现场使用时间长的炉辊周期维护提出了建议。     

连续退火炉内辊型对带钢瓢曲张力影响的试验研究

主要分析了在连续退火炉内热处理薄带钢时,炉辊的凸度、炉辊中间平台区长度以及辊面粗糙度等因素对带钢产生瓢曲的影响规律。旋转的炉辊对带钢宽度方向上产生一个压缩作用,这种压缩作用会引起带钢的弯曲和折皱,折皱经过炉辊后就会有可能引发热瓢曲。推导出一个计算瓢曲临界张力的公式,公式表明,临界瓢曲应力和[（带钢厚度×屈服强度）/（炉辊凸度×摩擦因数）]2成正比。     

连续退火炉内带钢张力设定模型研究

在现代化冷轧宽带钢连续退火生产线上,带钢有时会出现横向瓢曲,现场也称之为"热瓢曲",此一瓢曲对机组生产及产品质量危害极大.研究表明,"热瓢曲"与带钢张力设定正确与否密切相关.基于对带钢"热瓢曲"形成机理的新的认识和力学分析模型及有限元数值仿真结果,建立了一套合理的连续退火炉内带钢张力设定的方法和模型,并开发了张力设定软件供工厂使用,取得明显效果.     

连续退火炉稳定通板技术的改进与完善

简要介绍了冷轧连退机组使用的炉辊的形状、不同位置的炉辊在机组运行时凸度的改变情况,以及炉辊凸度改变对机组带钢产生瓢曲和跑偏擦边的影响.通过对连续退火炉内炉辊在热态下凸度变化情况的研究,在带钢规格变化过程中针对性地采用优化降速、降温等过渡策略,较大幅度地减少了瓢曲、断带的发生;同时,通过数据计算的方法,引入一个直观的瓢曲风险系数的方法,使操作更加直观.对所述方法的综合使用,基本消除了带钢瓢曲现象的发生,使生产稳定性得到了很大的提高.     

连退线上带钢瓢曲有限元仿真

带钢在连续退火生产线上,出现起皱现象,称为瓢曲。本文采用有限元软件模拟了带钢瓢曲的产生机理,首先是张应力的施加导致横向压应力的产生,然后带钢运动,导致横向压应力的进一步增大,壳曲率增大,塑性累积,最终瓢曲形成。通过对比分析,得到瓢曲临界张力,为设定合理的张力参数提供理论依据。     

CAPL均热室供热制度对炉温及带钢热瓢曲的影响

通过模拟实验研究和现场实际测试，找出了ＣＡＰＬ均热室在不同供热制度下，炉温和带温的分布规律，分析了它们对带钢产生热瓢曲的影响，提出了改进的措施。     

连续退火机组带钢瓢曲临界张力的研究

 根据金属塑性理论建立了带钢稳定通板的理论模型,并对模型进行求解,求解分为张力加载与辊子转动两步进行。系统地研究了瓢曲的形成与发展,以及辊形与带钢尺寸对带钢瓢曲临界张力的影响等。结果表明：引起带钢瓢曲的横向压缩应力由不均匀拉伸诱发的横向压缩应力和由摩擦产生的附加横向压缩应力两部分构成,瓢曲在带钢传输过程中逐步形成;对比发现有限元模拟的瓢曲发生与长大过程与大生产的情况基本一致,瓢曲的宽度约为2～4mm。并且带钢瓢曲的临界张力随着辊子凸度的增大、辊子平台区长度的减小、辊面粗糙度的减小、带钢厚度的减小而逐渐减小。     

Drug-associated hemorrhagic enteritis

Drug-associated hemorrhagic colitis are divided into antibiotic associated hemorrhagic colitis (AAHC) and other drug associated hemorrhagic colitis. AAHC are mainly caused by oral usage of Ampicillin and its derivatives (85%). Initially AAHC are believed to be caused by Klebsiella oxytoca overgrowth. However, these organisum has no exotoxin like Clostridium difficile and pathogenesis of AAHC are still unresolved. Typical AAHC are diagnosed by colonoscopy with diffuse hemorrhage and edema mainly found in descending colon and transverse colon. NSAIDs are also the cause of hemorrhagic colitis like AAHC. Mephenamic acid are famous for this complication. Diarrhea is one of the main complication of oral 5-fluorouracil administration and even causes hemorrhagic colitis. Its histology are characteristic in gland atrophy. Gold colitis are reported 36 cases in rheumatoid arthritis patients. Exact mechanism of bleeding are not understood. NSAIDs may cause collagenous colitis and or lymphocytic colitis in RA patients. Other rare hemorrhagic colitis are associated with azathioprine, methyl dopa, interferon alfa etc. NSAIDs and anticoagulants are well known drugs for complication of GI bleeding making hemorrhagic enteritis.     

Intracellular bacteria in protozoa

Intracellular bacteria in humans are typically detrimental, and such infections are regarded by the patients as accidental and abnormal. In protozoa it seems obvious that many bacteria have coevolved with their hosts and are well adapted to the intracellular way of life. Manifold interactions between hosts and intracellular bacteria are found, and examples of antibacterial resistance of unknown mechanisms are observed. The wide diversity of intracellular bacteria in protozoa has become particularly obvious since they have begun to be classified by molecular techniques. Some of the bacteria are closely related to pathogens; others are responsible for the production of toxins.     

Arachnoid cysts on computed tomography

The appearances of arachnoid cysts on computed tomography are presented. They are well defined lesions with the same density as cerebrospimal fluid and are not contrast enhanced. Superficial lesions are biconvex or semicircular and may have a characteristic straight inner margin. Deep lesions and cysts between the cerebellar hemispheres are spherical and some may be difficult to differentiate from cystic neoplasms. The etiology and clinical manifestations of arachnoid cysts are also briefly discussed.     

Optimum Design of Welded Steel Plate Girder Bridges Using a Genetic Algorithm with Elitism

The genetic algorithm (GA) is a general optimization technique that has some unique features that are especially suitable for structural engineering problems. This work uses a simple GA with elitism to find the optimum design of welded steel plate girder bridges. The objectives are to minimize the weight and the cost of the girders. Two types of plate-girder bridges are studied: a single-span bridge and a two-equal-span continuous bridge. Bridges with various span lengths, in increments of 20?ft, are investigated; results are tabulated, parametric studies are made, and meaningful conclusions are drawn.     

Positional anomalies of the intestine in adults

Anomalous intestine positions arise during embryologic development. They are rare in adults and cause uncharacteristic but chronic discomforts. They can produce life-threatening complications at any time. They are thought of too rarely, and radiologically shown anomalies are easily misinterpreted. Frequently they are discovered only during operation. The 178 anomalous intestine positions are here analyzed partly newly named and discussed to facilitate detection, to prevent complications, and to make rational treatment possible. There are 24 different typical forms, which are explained by disturbances of the embryologic rotation, growth, or fixation of the intestine.     

赣南钨矿山资源状况调查与思考

通过赣南钨矿山资源调查,反映钨矿山资源状况不容乐观。据地质报告中统计,赣南累计探明WO3储量149.98万t,其中上平衡表113.67万t,而保有储量仅有46.7万t;国有钨矿山保有储量26.4万t,可利用的储量10.4万t,可服务年限大都在10a以下。因此,建议尽快对赣南的国有钨矿山开展新一轮的地质找矿,寻找新的接替基地,控制钨矿产量,对尾砂综合回收和利用。     

Statistical theory of the hydrogen-induced phase decomposition of an amorphous zirconium-palladium alloy with the formation of metal hydrides. Hydrogen solubility in phases

A statistical theory is developed for the decomposition of an amorphous zirconium-palladium alloy in a hydrogen atmosphere with the formation of metal hydrides. The free energies of the phases are calculated, and equations for the equilibrium states of the phases are derived. The phase-transformation temperatures are determined, and their dependences on the system composition are obtained. The temperature dependences of the hydrogen solubilities in the phases are found, and the appearance of the inflection points or jumps at the phase-transformation points, which are experimentally observed as inflections in the dependences, is grounded. Hydrogen solubility isotherms are calculated, and the possibility of a hysteresis effect is revealed.     

浅谈推行标准化操作的实践

针对推标工作的指导思想、基本原则、基本步骤、具体做法、实施措施、工作速度,制定了有效办法,保证了推标工作的有序进行,克服了推标工作的随机育目性,在岗位操作标准制定时,打破以往三大进修规程的理论体系强,岗位操作弱的特点,抓典型、树样板、以点带面、以面推动全局。     

Models of helping and coping.

Draws a distinction between attribution of responsibility for a problem and attribution of responsibility for a solution. Four general helping models are derived. In the "moral" model, actors are held responsible for both problems and solutions and are believed to need only proper motivation. In the compensatory model, people are responsible only for solutions and are believed to need power. Individuals in the medical model are responsible for neither problems nor solutions and are thought to need treatment. In the enlightenment model, actors are responsible for problems but are unable or unwilling to provide solutions; they need discipline. It is maintained that each set of assumptions has characteristic consequences for the competence, status, and well-being of actors and that the wrong choice of model in a situation will undermine effective helping and coping. Competing models of responsibility in education, psychotherapy, law, and welfare are described, and research on attribution of responsibility is recommended as a way of addressing problems of both theoretical and social significance. (128 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)