重载列车作用下铁路钢桁梁桥的动力响应分析及疲劳寿命评估

以长东黄河大桥三跨连续钢桁梁为工程背景,采用ANSYS软件建立了有限元模型,对不同载重列车过桥时钢桁梁的动力响应进行了分析,并根据线性累计损伤理论,采用雨流法计数,对C80重载列车过桥时钢桁梁的疲劳损伤度及疲劳寿命进行了评估。主要结论为：列车车辆过桥时,随车辆轴重的增加,钢桁梁动挠度加大,但竖向加速度极值不严格随轴重的增加增大或减小;低速范围内随车辆速度的增加,钢桁梁动挠度变化不大,只有波动幅度增大,竖向加速度极值随车速的增加而增大。该钢桁梁在C80列车编组下的疲劳寿命约125 a,与C70列车编组下的疲劳寿命相差不大。     

关于知识经济的几个问题

本文对有关知识经济的一些基本问题进行了比较深入全面的论述。其中重点论述了知识经济的基本内涵、知识经济的基本特征、知识经济对当代与未来社会的作用与影响，以及如何迎接知识经济时代的挑战等重要问题     

Nesting Monte Carlo EM for high-dimensional item factor analysis

The item factor analysis model for investigating multidimensional latent spaces has proved to be useful. Parameter estimation in this model requires computationally demanding high-dimensional integrations. While several approaches to approximate such integrations have been proposed, they suffer various computational difficulties. This paper proposes a Nesting Monte Carlo Expectation-Maximization (MCEM) algorithm for item factor analysis with binary data. Simulation studies and a real data example suggest that the Nesting MCEM approach can significantly improve computational efficiency while also enjoying the good properties of stable convergence and easy implementation.     

挤压性围岩隧道变形特征分析

乌鞘岭隧道是兰新线重点控制工程，是国内最长的单线铁路隧道。该隧道岭脊地段穿越四条区域性大断层，地应力高，围岩软弱、破碎，属挤压性围岩大变形隧道。隧道施工过程中，出现较为严重的支护变形、支护开裂、钢架扭曲，甚至变形侵限及坍塌事故。针对该隧道特点，开展以变形为主的施工监控量测，进行了变形分布规律、累计变形与最大变形速率的关系、变形与围岩条件的关系以及变形与施工方法的关系等综合分析。提出挤压性围岩隧道具有变形量大、变形速率高、变形持续时间长的变形特征。     

浅析放松能力对短距离跑的作用

通过从生理、技术角度分析肌肉放松对短距离跑的作用以及影响短距离跑中放松能力的主要因素,得出加强放松能力的训练对提高短跑运动员的成绩有显著性作用,并提出了一系列与短跑相结合的提高放松能力的训练方法及心理训练方法。     

The Relations Among Relatedness Needs,Subjective Well-Being,and Depression of Korean Elderly

The first part of the study examined what the relatedness needs Korean elderly have in close relationships (spouse, children, friends) are. The most salient needs were “love and care” for spouse and “contact and often meeting” for children and friends. The second part of the study assessed the relations among the difference between expectation and satisfaction of relatedness needs, subjective well-being, and depression of Korean elderly. Regression analyses showed that the difference between expectation and satisfaction of relatedness needs for spouse and children significantly predicted subjective well-being and depression. Finally, gender differences are discussed in terms of the patriarchal culture of Korean society.     

The relationship among interactive justice,leader–member exchange,and workplace friendship

Workplace friendship is an important issue in business. Despite its predominance within the management field, there are several unaddressed issues. This study examines the relationship among interactive justice, leader–member exchange, and workplace friendship. Based on data collected from 309 full-time Taiwanese employees, results indicate that interactive justice is positively associated with workplace friendship. Leader–member exchange mediates such relationships. Therefore, as far as the manager is concerned, interactive justice is an effective factor for promoting workplace friendship and the mediating effect of leader–member exchange cannot be neglected.     

简论农地权利设计之理据——兼评《农村土地承包法(草案)》的有关规定

农地权利究竟如何设计 ,学者们提出了一些模式 ,但是 ,这些模式的共同缺陷是回避了农地权利设计的理据。这些理据在事实上乃为农民的生存与发展 ,在立法上应依据《民法典》。     

地区科技创新能力评价研究

在经济全球化和科技革命的今天,科技创新是提高地区经济竞争力的关键,是现代化建设的核心.本文利用主成分分析法的扩展-核主成分分析法对中国大陆三十一个省市区的科技创新能力进行分析和评价,找出影响科技创新能力的主要因素,并举例分析研究对象在主要方面的优势与不足,对地区发展有一定的借鉴价值.