仿古钢塔施工质量控制

近年来,随着经济和科技的飞速发展,我国的钢结构工程施工技术也有了飞速的发展.钢结构工程有着强度高、抗冲击和抗振动能力强、塑性和韧性好、抗震性能好等特点.其次,钢结构工业化程度高,有着加工精度高、制造周期短、生产效率高、建筑施工速度快等特点,这也为建筑施工赢得宝贵时间,可以得到无法估量的综合效益.在建筑工程中使用钢结构不但具有较高的现实意义,而且也是仿古工程未来发展的新趋势、新方向.这使得人们在钢结构工程施工质量和安全管理方面的重视度越来越高,做好钢结构工程施工质量控制和安全管理工作具有十分重要的价值和意义.本文以某仿古钢塔施工为例,介绍和总结了钢结构建筑在施工质量控制方面的一些技术和方法,以供大家参考.     

Investigation of Strain Rate Effect by Three-Dimensional Discrete Dislocation Dynamics for fcc Single Crystal During Compression ProcessEI北大核心CSCD

Microelectromechanical systems (MEMS) have become increasingly prevalent in engineering applications. In these MEMS, a lot of micro-components, such as thin films, nanowires, micro-beams and micropillars, are utilized. The characteristic geometrical size of those components is at the same scale as that of grain, the mechanical behavior of crystal materials exhibits significant size effect and discontinuous deformation. In addition, those MEMS are often subjected to high strain rate at work, such collision and impact loading. The coupling deformation characteristics of small scale crystals and high strain rate makes their mechanical behavior more complicated. Accordingly, investigation of the effect of the strain rate on crystal materials at micron scale is significant for both the academia and industry. In this work, a plastic deformation model of fcc crystal under axial compression was developed based on three-dimensional discrete dislocation dynamics (3D-DDD), which considered the influence of externally applied stress, interaction force between dislocation segments, dislocation line tension and image force from free surface on dislocation movement during the process of plastic deformation. It was applied to simulate the plastic deformation process of a Ni single crystal micropillar during compression under different loading strain rates. 3D-DDD and theoretical analysis are carried out to extensively investigate the effect of strain rate on flow stress and deformation mechanisms during plastic deformation process of crystal materials. The results show that the flow stress and the dislocation density increased with the loading strain rate. In the case of low strain rate, the flow stress was dominated by the activation stress of FreakRead (FR) source in plastic deformation. With the increase of strain rate, the contribution of activation stress of FR source to the flow stress decreases and the effective stress gradually dominated the flow stress. Under high strain rate loading, with the increase of the initial FR source, the dislocation density also increased at the same strain correspondingly, which makes it easier to meet the requirement of the loading strain rate, so the flow stress is smaller. In addition, under the low strain rate loading, a few activated FR sources can meet the requirement of the plastic deformation, a single slip deformation come up as a result. While, as the loading strain rate increases, more and more activated FR sources would be needed to coordinate the plastic deformation, the deformation mechanisms of the single crystal micropillar transformed from single slip to multiple slip.     

现浇钢筋混凝土楼面的裂缝分析与防治措施

现浇钢筋混凝土楼面的裂缝问题,是一个普遍存在而又难以解决的工程实际问题,特别是住宅工程楼板的裂缝发生后,往往会引起投诉、纠纷、以及索赔要求等。因此,在当前施工中如何克服现浇混凝土楼板裂缝,是一件非常重要的事情。通过对裂缝的成因进行分析,提出了预防措施和处理方法。     

透明质酸体系与水界面稳定性的分子动力学模拟

为考察仿生黏液透明质酸体系与水相界面行为随时间的变化规律,结合Forcite模块,采用Nose扩展系统控温法、Atom based计算方法和Ewald计算方法,通过分子动力学研究,探讨仿生黏液-水界面的分子之间的变化。以透明质酸的水溶液为代表,模拟生物黏液,从微观层面探讨界面稳定性：从界面张力、界面相互作用能、径向分布函数和均方根位移等方面分析影响界面稳定性的因素。结果表明：仿生黏液在透明质酸高分子多聚体和水分子在质量比为1∶10时的界面张力最小为61.33 mN/m,此时的单位界面能最低为242.67 kJ/(mol·nm²),界面最稳定。根据MSD曲线和RDF(径向分布函数),从水分子和透明质酸分子相互作用的强弱和水分子的移动也间接地表明在质量比为1∶10时,体系界面稳定性最高。模拟结果与实验的稳定性结果一致,从微观层面解释了透明质酸体系和水界面的一些规律。     

热压铸厚壁刚玉瓷的研制

分析研究了热压铸成型大件厚壁刚玉瓷生产中经常遇到的一些缺陷，探讨了其产生原因，并提出了解决这些问题的方法。     

湿陷性黄土地基处理方案试验研究

以一巨厚层湿陷性黄土场地地基处理多种方案的现场试验实例，对浸水试桩和高能级强夯的试验方法与结果作了阐述和分析，选择出该场地地基处理的最佳方案，并提出应采用的技术参数。     

用Delaunay三角形化实现的矩形边界表面描述算法

本文提出了一种基于Delaunay三角形化且定义在矩形边界上,具有形如Z=f(x,y)形式的表面描述算法.算法从一个简单的结构开始,在本文定义的描述误差D_K的指导下自适应地在合适的位置插入数据点以逼近实际表面,然后对旧的结构进行更新,从而获得任意精度的表面描述.对一组实际的三维物体的深度数据模拟实验表明,本算法具有程序简便,运算速度快,数据压 缩比高和存储量小的特点.     

汽车平顺性研究中“人—椅”系统模型再探

将汽车平顺性研究中人体振动模型从两自由度简化为单自由度。实例计算表明,单自由度模型既简化计算,又保持计算精度。     

多次波压制的自适应方法

多次波压制的自适应方法以预测相减的思路进行与地表相关的多次波压制，它需要根据能量最小准则反演子波。本文详细介绍了该方法的原理，并提出了一种快速有效的实现算法。由于子波长度远小于地震记录长度，利用SINC插值在频率域以稀疏的谱点确定子波形态。在此基础上进行计算，大大减少了反演参数的个数，并大大提高了方法的精度和速度。     

miR-143 Inhibits NSCLC Cell Growth and Metastasis by Targeting Limk1

MicroRNAs (miRNAs) have essential roles in carcinogenesis and tumor progression. Here, we investigated the roles and mechanisms of miR-143 in non-small cell lung cancer (NSCLC). miR-143 was significantly decreased in NSCLC tissues and cell lines. Overexpression of miR-143 suppressed NSCLC cell proliferation, induced apoptosis, and inhibited migration and invasion in vitro. Integrated analysis identified LIM domain kinase 1 (Limk1) as a direct and functional target of miR-143. Overexpression of Limk1 attenuated the tumor suppressive effects of miR-143 in NSCLC cells. Moreover, miR-143 was inversely correlated with Limk1 expression in NSCLC tissues. Together, our results highlight the significance of miR-143 and Limk1 in the development and progression of NSCLC.