嘉绍大桥刚性铰专用支座设计

嘉绍大桥为六塔独柱四索面钢箱梁斜拉桥,其主梁中跨跨中区域设置刚性铰。针对刚性铰结构的特殊要求,设计出一种具有柔性减振并可调节高度的球型钢支座。该支座由楔形板、轴承座、摩擦副、球冠衬板、橡胶减振垫、剪力卡榫、滑动板等组成。通过在刚性铰中的磨耗试验对比,支座摩擦副滑板材料选择了对温度的敏感程度和在相同压应力下摩擦系数均低于改性超高分子量聚乙烯的聚四氟乙烯。采用在下支座板上硫化一层橡胶减振垫的柔性减振措施减小支座承受的应力峰值,避免冲击破坏。通过对3种支座高度调节方案对比,选择了更适于刚性铰结构、操作简单、可无级调高且可以实现调低功能的楔形板调高方案。     

Decomposition analysis of decoupling freight transport from economic growth in China

Freight transport industry plays a significant role in boosting economic growth, while also creating many negative externalities for social welfare and the environment. Using data from 1997 to 2017, this study employs the complete decomposition technique to identify the driving forces of freight transport and explores its internal relations with economic growth in China. The decomposition analysis focuses on four factors that are responsible for freight transport: economic activity, industrial structure, transport intensity, and haulage distance. Then, the decoupling index is adopted to examine the decoupling relationship between freight transport and economic growth in China. The results showed that weak decoupling between freight transport and economic growth was the main state during the study period. A strong decoupling effect was identified in 1997–1998, 2012–2013, and 2014–2015, whereas no decoupling effect was observed in 1998–1999, 2008–2009, and 2011–2012. The transport intensity was the most important contributor to the decoupling progress, the industrial structure effect played a role in promoting the decoupling progress over half of the years during the research period, and the haulage distance effect facilitated the decoupling progress in more than one-third of the years examined.     

地铁振动对邻近建筑物影响及围护桩减振效果研究

依托北京某拟建住宅项目,采用现场监测方法获得地铁列车运行引起建筑物场区内地面振动的振动特性,并通过有限元分析软件建立地铁-土体-建筑一体化三维数值模型,预测拟建楼房的振动规律,预测结果与现场监测结果对比显示二者有良好的一致性,并分析采取基坑围护桩作为减振措施的应用效果。研究结果表明:(1)在地铁运行影响下,地面振动加速度级随着频率增加呈现先增大后减小的趋势;(2)对于10层左右的建筑物,地铁运行振动引起的动力响应随着楼层的增加,存在一个先减小后增大的过程,地面首层和顶层的动力响应最为显著;(3)基坑围护桩能有效减小建筑振动响应,各典型楼层最大Z计权振动加速度级均下降7~9 dB;(4)随着楼层的升高,建筑结构对30~40 Hz频段的建筑物竖向振动具有一定削弱作用。     

超弹性SMA唯象本构模型及其在震动控制中的应用

超弹性形状记忆合金(SMA)具有可恢复应变大、与其他基体耦合难度低以及耐腐蚀性能好等优点,是实施结构振(震)动控制的理想材料。为充分发挥超弹性SMA的减振(震)性能,必须寻找可准确描述其物理力学性能的本构模型。本文对Graesser-Cozzarelli(G-C)唯象本构模型进行拓展,通过在G-C模型中加入马氏体硬化项,描述超弹性SMA在大应变幅值工况下的应力-应变关系;设计一种具有自复位功能的位移放大型SMA减震装置,并将建立的超弹性SMA改进G-C唯象本构模型应用于该减震装置控制结构的动力时程分析。相关数值分析结果表明:改进G-C唯象本构模型形式简单、概念明确、参数容易得到,具有一定的工程应用价值,可为SMA基减震装置力学性能数值仿真及其在被动减震控制中的应用提供理论基础。     

Vibration analysis of super-yachts: Validation of the Holden Method and estimation of the structural damping

The hull excitation generated by marine propellers constitutes one of the most significant vibration sources affecting comfort on passenger ships. Consequently, the evaluation of the propeller-generated excitation through reliable numerical tools during the preliminary stage of ship design is fundamental. The Holden Method (HM) is an empirical tool utilized to calculate the propeller-induced pressure distribution on a ship hull. The present paper validates the HM, which is applied to a twin-screw, 54-m super-yacht. Finite Element Analysis (FEA) is used to benchmark the HM numerical predictions against a set of full-scale vibration measures. The outcomes show that the magnitude of the propeller-induced dynamic excitation predicted by the HM is overestimated. Thereafter, the calibrated propeller-induced forces and the diesel engine excitation are applied to the FE model to perform a series of forced vibration analyses and estimate the global structural damping coefficient of the super-yacht. The study highlights the necessity of developing new empirical methodologies, analogous to the HM, to be applied to modern small luxury vessels.     

在连通平面图上找Hamilton回路的一个方法

以图Ｇ的面为节点构造着色面状态树，用深度优选搜索法在状态树上找完全子树，以求对应的Ｈａｍｉｌｔｏｎ回路。为了把图Ｇ的全部Ｈａｍｉｌｔｏｎ回路都找出来，所需构造的着色面状态数的数目不会超过一个定值。     

25T型客车地板减振横梁改进方案

通过对25T型客车地板现有减振横梁与改进后的减振横梁在成本、强度、环保、装配等方面的对比分析,论证了改进方案的可行性。     

管理会计在船舶修造企业应用的理论探讨

文章主要介绍管理会计的基本原理和其区别于传统财务会计的独特之处,强调管理会计中的预测决策体系、全面预算管理及责任会计在船舶修造企业中的适用性,为管理会计在船舶修造企业的应用提出建设性的对策。     

集成谐波阻尼功能的单相光伏发电系统

针对单相LC型并网逆变器与电网阻抗间可能发生的谐振现象进行了研究。为了提高公共连接点电压质量,抑制背景谐波电压在公共连接点的谐振放大,将阻性有源滤波器的功能引入光伏并网逆变器。集成谐波阻尼功能的单相光伏并网系统可有效抑制背景谐波电压的谐振放大,但交直流侧瞬时功率交换会导致直流侧电压出现高频纹波分量脉动。为此,通过引入低通滤波环节和优化电压电流环参数设计,达到了减少直流侧电压纹波对电流环控制影响的目的。理论分析和仿真结果验证该方案的有效性。