带整流负载同步发电机稳定性研究

采用将带整流负载同步发电机中各变量的d、q轴低频分量和高频分量分别加以处理的方法,得出了带整流负载三相同步发电机的等效电路模型,以及小扰动条件下三相同步发电机整流系统的稳定条件,并通过试验加以验证,得到了阻尼绕组不能改善带整流负载同步发电机系统运行稳定性的结论。     

Calculation of strain amplification matrix for strain invariant failure theory based on representative volume element models with periodical boundary condition

Strain invariant failure theory (SIFT) is a micro-mechanics-based failure theory for multi-scale failure analysis of composite materials originally proposed by Gosse and Christensen. In this paper, the approach for obtaining strain amplification matrix which is a key step for the execution of SIFT is improved by adopting representative volume element (RVE) finite element models considering periodical boundary condition, based on which more actual deformation mode is reflected. The deformation modes and strain data at the characteristic points of the centroid cell of multi-cell RVE model are analyzed and taken as a reference. It can be concluded that more reasonable deformation mode and relationship between the micro-mechanical and macro-mechanical strain states are obtained by employing the new model. Finally, numerical examples are provided to illustrate the determination of strain amplification factors within the RVEs considering periodical boundary condition at the characteristic points.     

新型桩板结构路基在季节冻土区的适用性

针对莫喀(莫斯科—喀山)高速铁路季节性冻土区路基冻胀病害防治问题,提出了铺设保温板垫层的新型桩板结构路基.通过对聚苯乙烯泡沫塑料板(EPS)、聚氨酯板(PU)和挤塑聚苯乙烯泡沫塑料板(XPS)3种保温材料性能的对比分析,发现新型桩板结构路基中的保温板可采用在保温隔热、隔水防渗和抗压性能方面表现良好的XPS保温板.通过建...     

使用状态对焊钉连接件抗剪性能影响的试验研究

通过不同直径的正立、侧立和倒立焊钉连接件抗剪性能试验,研究混凝土浇注方向、焊钉所处使用状态对其抗剪刚度和使用阶段承载力的影响。     

基于层次分析法的船体舭部分段划分方案评价及优化

基于层次分析法梳理船体舭部分段划分的影响因素,构建方案评价分析模型,计算各评价指标的权重,实现量化的方案评价,针对优选方案在总段搭载吊装过程中权重得分较低,应用TSV吊装软件,分析并提出相应解决措施。     

实业家与慈善事业的结合——近代江苏实业家与晚清"义赈"的兴起

晚清时期的民间慈善事业在光绪初年时已发生一些新的变化,具体表现为江苏实业家成立新式慈善机构、改变传统赈灾观念、从事募捐善款、制定高效的放赈方式。实业家积极投身于大规模的民间赈灾活动,有力的促进了晚清时期“义赈”活动的兴起。     

SIMPLE METHOD OF PUNCHING AND RE-LOCATING TISSUES FOR MANUAL CONSTRUCTION OF TISSUE MICROARRAY

A series of human tissue samples and cultured cell lines were formalin-fixed and paraffin-embedded. Specimen cylinder ( 1.2 - 1.8mm) were punched by a modified bone marrow biopsy needle and arrayed on a recipient paraffin block. Microscopic analysis on the sections from this tissue microarray (TMA) block demonstrated that the spots of tissues and cells were well preserved, and the cultured cell samples were successfully embedded from 5 × 104 to 2 × 105 in number. These TMA sections were also suitable for immunohistochemistry and RNA in situ hybridization.     

海底隧道安全监测问题的几点思考

安全监测是海底隧道施工的重要保障措施之一。由于海底隧道具有与陆地隧道不同的环境特点,因此,也就带来了海底隧道安全监测的复杂性与高风险。为了切实解决海底隧道的安全监测问题,结合陆地隧道安全监测经验和海底隧道的环境特点,提出了海底隧道安全监测的基本原则和技术方法,包括海水渗透超前探测、岩层岩性超前探测、围压监测、隧道形变监测、隧道空间位置导向与定位监测等,为海底隧道安全监测方法设计提供了有益的基础依据。     

基于统计和有限元分析的裂纹敏感区确定方法

港口机械正在向大型、高速、重载方向发展,其金属结构的质量越来越大,它的缺陷会给机械工作带来隐患,而且一旦出现断臂等重大事故,将造成巨大危害[1].     

钢筋混凝土空心梁疲劳性能试验研究

对6根大比例钢筋混凝土空心梁进行静载和疲劳性能试验研究,每根梁取不同荷载幅度,研究不同疲劳次数下梁受压区混凝土和受拉区的钢筋的应变、梁的跨中挠度以及裂缝发展情况,得到不同的疲劳荷载应力幅作用下钢筋混凝土空心梁的疲劳寿命;根据试验结果拟合得到钢筋混凝土空心梁疲劳荷载作用下的S-N曲线,为由钢筋混凝土空心梁构成的桥梁结构寿命预测提供依据。对钢筋混凝土空心梁疲劳破坏后的钢筋进行静力学性能试验研究,了解钢筋混凝土空心梁疲劳破坏后钢筋力学性能的退化情况。