不同流道间隙下矩形通道临界热流密度的实验研究

在氟利昂工质条件下,进行1~3 mm间隙的矩形通道临界热流密度(CHF)的实验研究。研究发现,在1~3 mm间隙的矩形通道内,随着压力的升高,CHF稍有下降;质量流速对CHF的影响呈非单调关系,在低含汽率区随着质量流速的增大,CHF增大;在高含汽率区,随着质量流速的增大,CHF减小;临界含汽量的增加导致CHF明显降低。综合分析表明,在本实验工况参数范围内,流道间隙范围为1~3 mm的矩形通道在相同的工况参数条件下,其CHF基本不受流道间隙的影响。     

Finite element numerical simulation on thermo-mechanical behavior of steel billet in continuous casting mold

The thermo-mechanical behavior of a thin, growing shell during the early stages of solidification in a continuous casting mold is very important to the ultimate quality of the final billet. A two-dimensional, transient finite element model has been developed to treat the heat flow and deformation of the solidifying shell in the continuous casting billet mold as a coupled phenomena. The major application of the model is to predict the extent of the gap between the mold and the shell and focus on the influence of mold taper on the thermo-mechanical behavior of the steel billet to help to understand the formation of off-corner cracks and break-outs in the solidifying shell. The calculations indicate that the gap is initially formed at the corner of the billet, where heat transfer is greatly reduced. Insufficient mold taper contributes to a hot spot in the off-corner region, which corresponds to the lowest shell thickness. At the same time, the solidifying front on the diagonal of the billet is subjected to an excessive mechanical strain, which causes the off-corner cracks and even the break-outs.     

环缝洗涤装置在宝钢4#高炉的应用实践

介绍了宝钢分公司4#高炉环缝清洗煤气的工艺流程及环缝洗涤装置的结构.从流体力学的角度阐述环缝不易磨损的机理.环缝洗涤装置的结构使气流在环缝内的分布更均匀,形成较小的速度梯度,产生的摩擦阻力小;直径更小的雾化水粒能有效捕集尘粒.运用理论结合生产实绩分析说明了环缝洗涤装置具有水气比低、压损小、除尘效率高的特点,环缝洗涤装置的水气比较二级文氏串联工艺低7.6%,压损率小0.89%.经环缝洗涤后的净煤气含尘量及含水量低,这有利于减少对用户设备的影响,减少向大气排尘,有利于环保.     

MOCVD法异质外延GaP/Si薄膜的研究

微电子和光电子材料兼容的技术是未来功能器件中的一个重要方向,它可以将成熟的Si集成工艺和GaP优良的发光特性结合起来,完成新一代微型显示和集成光学元件.我们用MOCVD方法在Si衬底上异质外延GaP薄膜,通过X光双晶衍射和能谱分析,在国内用MOCVD方法首次获得了GaP/Si的单晶薄层,并研究了它们的结构特性.     

发达国家宽带战略及我国与其发展差距分析

介绍国际宽带发展趋势,结合欧盟、美国、日韩等国发布的与宽带发展密切相关的国家战略,分析这些国家宽带战略的定位、战略目标、主要举措等内容;简述我国宽带发展状况,并分析与发达国家的差距,提出我国未来宽带发展的重点。     

Mind the gap: training road users to use speed and distance when making gap-acceptance decisions

Accurate gap-acceptance decisions require individuals to take into account both the distance to and the speed of an oncoming vehicle. The aim of the present studies was to develop an intervention that could successfully teach road users to focus on speed as well as distance. Across three studies, participants judged whether it was safe to cross the road or not when an oncoming vehicle was approaching from different distances and at different speeds. Study 1 trialed two techniques (“standard feedback” versus “three-look”) aimed at improving gap judgments. Standard feedback involved telling participants what the actual speed of a car was after they had made an estimate, whereas the three-look technique required participants to make timed and controlled head movements when scanning the road environment. Only standard feedback increased the participants’ mean gap-acceptance accuracy (assessed using both verbal and behavioral response measures). Study 2 also trialed two techniques, the standard feedback intervention used in Study 1, and a “two-response” intervention in which participants judged whether the oncoming vehicle was traveling at an atypical or normal speed. Study 2 found the two-response intervention to be more promising than the standard feedback procedure. Finally, Study 3 used video footage of oncoming vehicles to train younger (18–27 years) and older (60–80 years) adults and found the two-response intervention to be successful at improving gap-acceptance accuracies for both age groups. However, the intervention also resulted in more conservative gap judgments from participants in the older population independent of improvements in accuracy.     

辊缝仪在板坯连铸机中的应用

辊缝仪是检测板坯连铸机零段、扇形段辊缝、外弧辊对接状况和外弧辊对中状况的高精度检测仪器,其控制精度可达±0．1mm。介绍了辊缝仪的定义、检测原理及测量方法,并在实际应用中取得了良好的效果。     

考虑铰间隙的折叠翼展开机构展开过程碰撞动力学仿真分析

基于“二状态模型”的非线性等效弹簧阻尼模型,建立折叠翼展开机构的铰间隙碰撞模型,利用ADAMS软件对折叠翼展开机构的展开过程动力学进行仿真分析．包括间隙大小和间隙摩擦在折叠翼展开机构展开过程中引起的碰撞力变化规律。结果表明,在折叠翼展开机构整个展开过程中,由于间隙的影响,产生随机持续的碰撞力;随着间隙增大,碰撞次数减少,碰撞力幅值有增大的趋势;摩擦加快系统能量的损耗,一定程度上抑制了间隙碰撞次数和展开机构动力学扰动效应。     

全液压矫直机的四缸同步协调控制

矫直机主液压缸辊缝的控制效果直接影响到系统稳定性、产品质量、设备安全。重点研究主液压缸的辊缝控制策略,针对矫直机主液压缸平行压下的同步要求,提出一种基于单缸辊缝闭环控制与倾摆辊缝闭环控制的改进的4缸同步控制策略。该策略不仅能够实现矫直机的倾斜、摆动辊缝控制,也能提高4缸平行压下的同步性。通过在东北某厂热处理生产线的成功应用,证明该控制策略及技术的有效性,可在矫直机上广泛应用。     

怀旧心理与创新意识对中国结的影响分析

从怀旧倾向及中国编结的艺术创新共同作用于消费者购买意愿的角度出发,对中国编结艺术进行了实证分析。在此基础上,以南北地域差异(上海、北京为首)为考量,对消费者进行怀旧心理与创新意识的调查。结果显示:南北方存在着显著差异;南方消费者的不安全感及中国结的色彩创新在购买意愿上占了很大的额度,北方消费者的孤独感及中国结的应用范围在购买意愿上占了很大的额度。根据消费者购买意愿的调查分析及南北地域差异性,提出对策:针对南方中国结市场,应设计不安全感的广告理念,以及加强中国编结的色彩创新;针对北方中国结市场,应设计孤独感的广告理念,以及加强中国编结应用范围的创新。