大容量低温水溶性PVA纤维生产线的开发

简介了低温水溶性PVA纤维的性能特点、应用领域、国内现状和纺丝工艺。结合以往低温水溶性PVA纤维生产线的设备配置情况,并根据单机设备的特点和适用范围,对产能为1 800 t/a的低温水溶性PVA纤维生产线的流程进行了设计。重点对该生产线上主要专用设备的工艺特点和结构特点进行了分析。指出若要进一步提高产能,纺丝机可考虑采用层叠式结构,干燥机导丝辊的支撑方式应考虑采用双支撑式结构。     

Combinatorial Measurement of CDKN1A/p21 and KIF20A Expression for Discrimination of DNA Damage-Induced Clastogenicity

In vitro mammalian cytogenetic tests detect chromosomal aberrations and are used for testing the genotoxicity of compounds. This study aimed to identify a supportive genomic biomarker could minimize the risk of misjudgments and aid appropriate decision making in genotoxicity testing. Human lymphoblastoid TK6 cells were treated with each of six DNA damage-inducing genotoxins (clastogens) or two genotoxins that do not cause DNA damage. Cells were exposed to each compound for 4 h, and gene expression was comprehensively examined using Affymetrix U133A microarrays. Toxicogenomic analysis revealed characteristic alterations in the expression of genes included in cyclin-dependent kinase inhibitor 1A (CDKN1A/p21)-centered network. The majority of genes included in this network were upregulated on treatment with DNA damage-inducing clastogens. The network, however, also included kinesin family member 20A (KIF20A) downregulated by treatment with all the DNA damage-inducing clastogens. Downregulation of KIF20A expression was successfully confirmed using additional DNA damage-inducing clastogens. Our analysis also demonstrated that nucleic acid constituents falsely downregulated the expression of KIF20A, possibly via p16 activation, independently of the CDKN1A signaling pathway. Our results indicate the potential of KIF20A as a supportive biomarker for clastogenicity judgment and possible mechanisms involved in KIF20A downregulation in DNA damage and non-DNA damage signaling networks.     

乙烯裂解炉及其管道设计

乙烯是最基本的化工原料之一,对我国经济发展起到重要的支撑作用。结合以往工程设计的实践经验,简要介绍了几种乙烯裂解炉的型式与特点,并就乙烯装置裂解炉的管道设计谈了自己的思路与方法,对裂解炉区重要管系的设计进行了分析和说明。     

AGC在京唐1580生产线的应用及改进

分析了轧制过程中轧辊偏心产生的原因以及对带钢厚度的影响,增加了轧辊偏心补偿的方法,然后推导了主要结果并分析了其机理,并应用于京唐1580生产线实际的带钢厚度自动控制系统(AGC),通过实践,此种形式控制方式具有较好的精确性。     

钢筋混凝土缺角板受弯性能试验研究

为了研究混凝土缺角板的受弯性能,设计制作了角部不同开孔大小的7块钢筋混凝土四边简支板,并进行了静力受弯性能试验。结果表明：缺角板跨中区域钢筋先于板四周区域钢筋屈服,随后屈服范围不断扩展并往四角延伸,最终板顶缺角处沿与板边大致成45°方向的混凝土被压碎;开孔系数(板角所开孔洞边长与跨度的比值)为0.05、0.08、0.10、0.12、0.15和0.20的缺角板极限荷载较矩形板的极限荷载分别降低5.98%、10.35%、21.37%、23.63%、38.50%和49.29%,开裂荷载、屈服荷载基本随开孔系数的增大而降低。根据钢筋混凝土板塑性极限分析的塑性铰线法,对6块不同开孔系数混凝土缺角板提出了4种塑性铰线模式,并利用虚功原理建立缺角板极限荷载计算公式,极限荷载计算值与试验值吻合较好,验证了所提出的塑性铰线模式的合理性,及利用虚功原理建立缺角板极限荷载计算公式的可行性。引入一个与开孔系数相关的系数对塑性铰线模式进行简化,简化公式得出的计算值与试验值吻合较好。     

An efficient approach for traffic load modelling of long span bridges

Traffic micro-simulation is the newly developed approach for loading calculation of long span bridges. The approach is quite precise, but computationally expensive to consider the full extent of traffic loading scenarios during a bridge lifetime. To address this shortfall, an efficient multi-scale traffic modelling approach is proposed. The proposed approach uses micro- and macro-simulation with different load model varieties (LMVs), or fidelities (levels of detail) of traffic loading in different bridge regions, to achieve optimal computation efficiency while maintaining the precision of loading calculation. Metrics of influence line (IL) characteristics, such as degree of nonlinearity, are proposed to evaluate the appropriateness of the choice of LMV, and standards of the metrics are also investigated to quantify the implementation of LMVs on bridge IL regions in the multi-scale modelling. Finally, two typical ILs are used along with random traffic modelling to study the feasibility of the proposed approach. It is shown that the multi-scale modelling approach proposed here achieves high computational efficiency and accuracy, which is significant for the massive traffic load simulation for lifetime bridge load effect analysis.     

高精度机器人打磨系统标定算法研究与实现

针对自主研发的机器人打磨系统打磨精度差等问题,通过误差源分析,分别在工具、工件标定算法及实现方面进行了研究。针对打磨使用刀具的特点,选择合适的工具标定算法,设计辅助标定工装,完成了打磨工具的位姿标定,提高了打磨工具的标定精度。同时根据打磨工件标定算法及工件的特点,设计标定块,利用辅助特征点三点标定方法及合理的测量方法,完成了工件的高精度匹配。通过离线编程生成打磨程序,从而实现了高质量、高精度的机器人打磨作业。     

北京中关村科技园区城市生命线工程的防灾减灾

海淀区地处北京的西北部 ,中关村科技园区海淀园为其核心区域。本文从中关村科技园区的发展概述入手 ,论述了城市生命线工程的内涵和所关注的问题 ,阐述了国内外防灾减灾研究的发展趋势。通过调研对中关村科技园区防灾减灾的现状和存在的问题进行了初步分析 ,并提出相关的对策和建议 ,做到防患于未然。     

预应力连续梁桥预制悬臂拼装线形控制研究

通过蕉门河大桥的施工控制实例,论述了短线法预制预应力连续梁桥悬臂拼装施工线形控制的基本原理、控制方法及其分析计算方法,用以确定结构的合拢精度和成桥后的线形,为短线法预制悬拼工艺的推广提供了理论铺垫。     

单测线法估算随机节理迹长的数值技术

由于现场条件的限制，有时只能采用单测线法来估算随机节理的真实迹长，即随机节理迹长取样偏差的纠正。为了更准确地估算随机节理的真实迹长，建议首先采用随机节理优势组数的概率统计划分方法，将测线法获得的随机节理进行优势组数划分；获取每一条随机节理的观测迹长和每一组节理的平均观测迹长；应用概率统计的方法求得每一组节理迹长的概率分布密度特征函数；最后，采用半迹长估算法来实现各组随机节理的迹长取样偏差，获得了较符合实际的成果。