小水线面双体船结构疲劳强度评估

以"小水线面油田交通船"为依托,探讨了小水线面双体船结构疲劳强度的评估方法,包括:疲劳强度评估构件及部位的确定、疲劳载荷、设计应力范围以及累积损伤度计算等问题.     

轨道交通明挖矩形隧道曲线地段建筑限界的计算

在总结目前国内轨道交通限界计算方法研究的基础上,说明了建筑限界计算方法研究的必要性和重要性。提出了明挖矩形隧道直线段、平曲线地段建筑限界计算方法, 给出了缓和曲线地段建筑限界计算的方法和公式的推导,并结合算例进行了探讨。     

永磁推进电机的电枢反应与应对措施

本文介绍了永磁推进电机的表面式转子磁路结构和切向式转子磁路结构电枢反应的特点,并结合实例分析了这两种磁路结构的电枢反应对电机性能的影响.介绍了国外研制永磁推进电机的动态.提出了带极靴的表面式磁路结构并分析了这种磁路结构交轴电枢反应的影响,强调应通过试验进行验证.     

含损伤加筋板结构辐射声功率及指向性变异研究

本文采用结构声振特性中常用参数辐射声功率和辐射指向性来研究含损伤加筋结构的声辐射特性,计算不同加筋情况和结构不同损伤情况下的辐射声功率和远场指向性.基于Mindlin理论,建立描述健康和损伤的四结点有限元板壳单元模型,采用有限元方法计算结构表面动力响应.针对各向同性损伤单元,采取刚度各向整体弱化的方法分析;对于各向异性损伤单元,采用Kachanov理论,引入了x和y两个方向的弹性损伤折减系数.根据Rayleigh积分可以计算结构振动向外辐射的声压,进而可以得到辐射声功率和辐射指向性.考虑到不同损伤存在形式,计算分析了损伤对振动频率、模态以及辐射声功率和指向性的影响.文章建立了一种含损结构的分析方法,通过对一些典型算例分析,在评价损伤对船舶与海洋结构物常用的加筋结构声辐射特性影响方面做出了一定的探索.     

半断面法超前周边注浆在煤层采空区治理中的应用

以煤层采空区治理工程为依托,详细介绍了超前周边注浆参数的选取原则,讨论了全断面注浆和半断面注浆作业的优缺点和适用范围.介绍了周边注浆施工材料、设备及施工工艺,采用分析法和检查孔法对注浆效果进行了对比分析.结果表明,采用超前周边注浆加固,能有效控制涌水量,加固松散岩体.     

船舶下舵承间隙及结构问题分析与对策

结合船舶下舵承在设计、安装和船舶营运过程中面临的问题,根据船级社相应规范和标准对船舶下舵承的规定,分析舵承间隙及结构,提出相应的解决方案。实践证明该方案可行。     

Evolution of latent modal captivity and mode choice patterns for commuting trips: A longitudinal analysis using repeated cross-sectional datasets

This paper presents an investigation of the temporal evolution of commuting mode choice preference structures. It contributes to two specific modelling issues: latent modal captivity and working with multiple repeated crossectional datasets. In this paper latent modal captivity refers to captive reliance on a specific mode rather than all feasible modes. Three household travel survey datasets collected in the Greater Toronto and Hamilton Area (GTHA) over a ten-year time period are used for empirical modelling. Datasets collected in different years are pooled and separate year-specific scale parameters and coefficients of key variables are estimated for different years. The empirical model clearly explains that there have been significant changes in latent modal captivity and the mode choice preference structures for commuting in the GTHA. Changes have occurred in the unexplained component of latent captivities, in transportation cost perceptions, and in the scales of commuting mode choice preferences. The empirical model also demonstrates that pooling multiple repeated cross-sectional datasets is an efficient way of capturing behavioural changes over time. Application of the proposed mode choice model for practical policy analysis and forecasting will ensure accurate forecasting and an enhanced understanding of policy impacts.     

现代有轨电车轨道结构综述

通过对国内外的现代有轨电车轨道结构的研究与发展现状进行归纳、总结,对有轨电车轨道结构进行初步分类,并详细介绍几种国内外应用较多的现代有轨电车轨道结构的组成、特点及其应用情况,结合我国现有的技术特点,提出我国现代有轨电车轨道结构设计的一些建议。     

Detection of nonlinearity effects in structural integrity monitoring methods for offshore jacket-type structures based on principal component analysis

The detection of changes in the dynamic behavior of structures is an important issue in structural safety assessment. The development of detection methods assumes greater significance in the case of offshore platforms because the inherent problems are compounded by the harsh environment. Here, we describe an instrumented physical model for the structural health monitoring of an offshore jacket-type structure and the results of tests in several different damage scenarios. In a comparative investigation of two different methods, we discuss the difficulties of implementing damage detection techniques for complex structures, such as offshore platforms. The combined algorithm of a fuzzy logic system and a model updating method are briefly discussed, and a method based on stochastic autoregressive moving average with exogenous input is adopted for the structure. The consideration of uncertainties and the effects of nonlinearity were major objectives. So, the methods were also investigated based on the test scenarios consisting of the physical model with a geometric nonlinearity. The principal component analysis method was utilized for the detection of nonlinearity in the recorded data. The results show that the developed methods are suitable for damage classification, but the quality of the acquired signals must be considered an important factor influencing successful classification. The development of these methods may be extremely useful, as such technologies could be applied for offshore platforms in service, enabling damage detection with fewer false alarms.     

宿淮铁路(江苏段)桥梁设计技术创新

介绍宿淮铁路2座特大桥结构体系设计创新特点。理论计算分析表明:采用主跨132 m连续梁-拱组合体系单线桥可有效降低梁高,节省造价,施工和运营状态下,结构的强度、刚度、横向稳定、行车舒适度性等指标均满足规范要求;主跨108 m连续梁采用双向减隔震体系后,正常使用状态及多遇地震下结构正常工作。当设计地震及罕遇地震发生时,减隔震体系显著降低地震反应,避免了重要部位破坏,保证了桥梁结构的安全性,具有明显的经济效果。