SWRH82B钢Φ14 ~ 15 mm盘条的生产实践

采用Cr、V微合金化技术开发了抗拉强度≥1180 MPa的SWRH82B钢Φ14～15 mm盘条(/%:0.79～0.82C,0.15～0.35Si,0.60～0.90Mn,≤0.025P,≤0.006S,≤0.015As,0.26～0.32Cr,0.04～0.07V)。水钢用100 t转炉-LF精炼-160 mm×160 mm连铸(结晶器带电磁搅拌)-铸坯缓冷-高速线材轧制-Stellmor风冷的工艺流程生产的SWRH82B钢Φ14～15 mm盘条组织的索氏体化率达到了95%。盘条的抗拉强度为1 180～1 270 MPa,断面收缩率为27.0%～37.5%。盘条满足大规格高强度矿用钢绞线的要求。     

A methodological approach for finite element modeling of pretensioned concrete members at the release of pretensioning

This paper presents a methodological approach for finite element simulation of pretensioned concrete members. The three-dimensional analysis presented in this paper involves a rectangular [150 mm (6 in.) tall × 150 mm (6 in.) wide × 2440 mm (96 in.) long] concrete member hosting one 15-mm (0.6 in.) diameter 7-wire low-relaxation Grade 1860 MPa (270 ksi) prestressing strand. The finite element models are divided into two general classifications: (i) concentrically pretensioned, and (ii) eccentrically pretensioned. The finite element models are analyzed based on elastoplastic material behaviors as well as mesh sensitivity. Two approaches are examined for finite element modeling of the pretensioned concrete specimens: (i) the extrusion technique utilizing friction-based contact simulations, and (ii) the embedment technique simulating equivalent responses while being a computationally less expensive solution. A comparative analysis is presented to measure the validity as well as accuracy of the findings by the finite element techniques against the commonly used closed-form solutions based on elastic beam theory. The validity of the finite element approach is further verified by comparative analysis of the analytical data against the experimental findings. The paper concludes that the embedment technique provides an accurate and numerically efficient alternative in comparison with the extrusion method for the simulation of the pretensioned concrete members. While the extrusion technique provides more detailed information corresponding to the regions located immediately around the prestressing strands, including the interface overstresses and bond slippage, the embedment technique appears to have the ability to simulate the overall response of the concrete members with comparable accuracy.     

~(60)Coγ射线诱发的中国田鼠V_(79)细胞和小鼠胸腺细胞DNA单链断裂及其修复的研究

本文对~(60)Co γ射线诱发的中国田鼠肺成纤维细胞(V79)和小鼠离体胸腺细胞 DNA 单链断裂及其重接修复进行了实验研究。实验结束表明,两种细胞 DNA 单链断裂的程度分别在30Gy 和10Gy 剂量范围内与剂量呈线性相关;V79细胞 DNA 单链断裂的重接修复包含有快修复和慢修复过程;在不加血清的 TC199培养液中 V79细胞 DNA 断链仍能重接修复,而离体小鼠胸腺细胞在不加血清的 TC199或 RPM11640培养液中其 DNA 断链均不能重接修复,表明不同细胞 DNA 断链的重接修复所要求的细胞培养条件不同。     

特殊非对称型12流35 t中间包的水模拟试验和控流装置的优化

通过几何相似比1:3的水模型试验分析了钢厂特殊非对称型12流200 mm×285 mm铸坯的35 t中间包的结构特点,得出原中间包不对称度较大,结构不合理,整体混匀效果和各流的一致性较差,需要设计有效的控流装置以改善其内部流动。水模拟结果表明,通过所设计的相对较大的冲击区和两个导流孔的优化方案,使得中间包的整体混匀效果和各流一致性都得到明显改善,其总体死区比例相对原型的27.96%降至8.94%;其各流平均停留时间的标准差降低74%。     

Physical modelling investigation of influence of strand blockage on RTD characteristics in a multistrand tundish

Abstract

In the continuous casting process, the tundish acts as a continuous molten steel distribution vessel. The importance of the tundish during the molten steel delivery becomes more significant when it supplies liquid steel to more than one mould. In the present work, a water model of a six strand billet caster tundish has been used to study the effect of strand blockage on the residence time distribution (RTD) characteristics at the strands. All the experiments were performed under steady state conditions. Potassium chloride was used as a tracer for the study. The effects of blockage on the strand dissimilarity among the open strands were also studied. Both single and dual strand blockage experiments were performed. Blockage of strands deteriorated the RTD characteristics at the open strands. The results reveal the most preferred options for strand blockage when the plant operation needs to do so.     

石壕煤矿中央泵房加固技术研究与应用

石壕煤矿井底中央泵房埋深大,周围巷道和硐室较多,由于扩修的影响,中央泵房围岩破碎,变形较大,影响了矿井的安全生产。通过对石壕煤矿中央泵房围岩内部结构的调查研究,提出了采用注浆加固配合高强树脂锚杆、锚索(部分为对穿锚索)的综合加固方案。这项技术在实践中的成功应用,解决了井底中央泵房大变形支护困难的问题,具有推广应用价值。     

定向结构刨花板表面粗糙问题的研究

本文对定向结构刨花板表面粗糙问题从工艺和设备上进行深入的研究 ,通过气流铺装施加表面细化材料以提高板面平整度。研究表明 ,采用细化材料的方法是可行的 ,产品质量达到加拿大国家标准二级板的要求。     

基于DNA链置换的赢家通吃神经网络

DNA链置换技术广泛用于生物计算中,在计算能力和信息处理方面表现出色.但是,在信号的放大、恢复与比较等一些计算中使用DNA链置换技术,不仅增加DNA链的数量,还会带来额外的计算成本.因此,为了减少DNA链的使用数量,该文构建了一个基于DNA链置换实现的赢家通吃(WTA)神经网络.首先,通过神经元实现逻辑运算AND,NA...     

关于点接触钢丝绳股结构设计与工艺参数的探讨

对沿用的点接触钢丝绳股结构计算和捻股工艺参数作了简要分析，同时提出了新的计算方法和捻股工艺参数，供讨论和在实践中进行验证。     

连铸过程中铸坯应变对碳氮化铌析出行为的影响

采用应变诱导析出模型分析了连铸过程中铸坯应变对碳氮化铌析出行为的影响。结果表明:拉速变化对碳氮化铌的最快析出时间有一定的影响,在同样的应变及应变温度下,拉速越快碳氮化铌最快析出时间越短;在连铸过程的矫直段及弯曲段,由于铸坯应变及应变速率较小,在研究连铸过程碳氮化铌析出行为时铸坯应变对碳氮化铌析出行为的影响可以忽略。