浇筑密实度和均匀度对结构混凝土耐久性的影响

为建立浇筑期结构混凝土耐久性质量控制方法,采用振动分层法,研究了混凝土浇筑密实度、浇筑均匀度对其渗透性的影响,建立了混凝土浇筑密实度和浇筑均匀度的量化控制方法——电阻率稳定区间法.结果表明:混凝土浇筑密实度和浇筑均匀度均决定于材料流动性和振捣时间;相比混凝土抗压强度,混凝土渗透性对浇筑密实度和浇筑均匀度更为敏感.通过计算量化判定电阻率稳定区间(SRER),并以其起点为判别点,可以保证混凝土浇筑密实度和浇筑均匀度处于综合最优状态,优化混凝土孔隙结构,显著提升混凝土抗渗透性能.     

A novel two-stage constraints handling framework for real-world multi-constrained multi-objective optimization problem based on evolutionary algorithm

Applied Intelligence - Multi-constrained multi-objective optimization is a challenging topic, which is very common in dealing with real-world problems. This paper proposes a novel two-stage ρg...     

考虑制动器温度的连续长大下坡纵坡设计方法

为提升连续长大下坡路段安全水平,研究一种基于制动器温度的纵坡设计方法。以7个典型连续长大下坡路段为研究对象,分析了下坡速度、车辆总质量对特定连续长大下坡路段货车制动器温度的影响。并以车辆到达连续长大下坡终点的制动器温度、制动器温度达到200℃和260℃时距连续长大下坡起点的距离为特征值,分析了采用等效平均纵坡单一坡度和设置缓坡两种展线形式对货车制动器温度的影响,提出了连续长大下坡路段区段划分量化标准和纵坡设计建议。研究表明：从降低货车制动器温度角度考虑,连续长大下坡路段应尽可能采用单一坡度展线,相邻坡段采用不同纵坡坡度时坡差不宜过大,特别是下部区段。     

振弦式位移计校准方法的研究

振弦式位移计在水运工程等领域广泛应用,但是国内一直未发布与其专门相关的检定规程或校准规范,缺乏完整的振弦式位移计溯源方法。该文介绍了振弦式位移计的工作原理,提出了振弦式位移计的具体校准方法,选取样机进行了试验测量,论证了校准方法的可行性,为振弦式位移计的质量控制提供了保障。     

基于HHT的柴油机气阀漏气振动诊断方法研究

介绍了采用Hilbert-Huang Transform(HHT)信号分析方法提取柴油机缸盖振动信号中气阀漏气特征的试验研究。通过气阀漏气的故障模拟试验,测量了柴油机气阀不同状态下的缸盖振动信号,分析确定了缸盖振动信号的分析段;运用HHT分析方法提取了气阀漏气时频域故障特征参数。研究发现:当气阀处于正常状态时其振动信号能量主要集中于上止点附近;当气阀处于漏气状态时能量向压缩冲程转移,分布更为均匀。表明:表征能量分布均匀程度的时频熵可以作为气阀漏气故障特征参数。     

真空预压法加固软土地基的工程实例分析

以黄骅港四期筒仓地基处理工程为例,详细阐述了真空预压加固软土地基施工过程中的仪器设备的布设、施工与监测方法;对工程实际的观测结果进行了分析。实践证明,真空预压加固法不仅加固时间短,施工成本低,而且对地基的加固效果明显。     

新一代智能交通系统的技术特点和发展建议

智能交通系统(即ITS)是现代交通技术的前沿之一,在国内外已有大量应用。随着新一代信息技术的发展和出行者需求的变化,ITS领域出现了与以往不同的、特色鲜明的技术方向和服务应用。本文首先对近期国内外ITS技术发展的最新动态和应用案例进行了分析,特别强调了新一代信息技术带来的技术跨越和关注领域的变化,提出新一代智能交通系统已初步形成。然后对新一代智能交通系统的技术特征进行了分析:各交通参与单元之间的互联、车辆对周边复杂环境的识别、新型的交通信息采集和服务、交通大数据、自动驾驶等。最后就新一代智能交通系统发展提出了建议:加快市场化,建立智能交通系统标准化的新模式,加强前沿技术开发等。     

Uncertainty Analysis of Flood Control Design Under Multiple Floods

Hydraulic engineerings built on tributaries at the confluence of main and branch streams are significant to river management and runoff regulation. The Flood Control Design Level (FCDL) calculations for these works are directly influenced by tributary floods and supporting effects from the mainstream. However, the determination of design level under main and tributary floods has not been well investigated. To address this issue, the authors proposed a Copula-based approach to analyze the design level under multiple runoff discharge with a case study of the Guiping Shipping Hub(GPSH). The proposed method is compared with the conventional multivariate hydrological elements analysis approach, and the sampling uncertainty is also studied. The results showed that the joint distribution of main and tributary floods is well modeled by Clayton Copula, with PE3s as the best-fit marginal distributions. Furthermore, the different roles of main and branch fluxes in design level calculation can be identified by the offered Flood Control return period(FCRP). And the design levels conducted by the FCRP can avoid the situation over-or-under performed by the OR or AND RP. Moreover, flood combinations uncertainty analysis indicates that the uncertainty of the joint design combinations decreases with the increase of sample size n but increases with the rise of the design T. Finally, the 95% confidence interval and standard deviation of the design level calculated by FCRP are smaller than that of OR RP, which means the FCRP can reduce uncertainty under multiple floods. These results suggest that the proposed FCRP provides an appropriate approach for determining the design level under combined fluxes and serves as a reference for engineering practice.

     

非线性遗传优化海域水质耦合模型多参数反演方法研究

通过遗传算法和海域水质模型的有机耦合,提出了基于非线性遗传优化海域水质耦合模型多参数反演的新方法.将海域水质模型嵌入遗传算法模型中,以海域内部验证点位的误差函数为适应度,进行模型多参数的优化反演.文中以渤海湾海域水质模型多参数反演的“孪生”试验来验证方法的有效性.数值结果表明:该反演新方法具有较高的精度.