磁场与高分子絮凝剂协同强化混凝降铝效能研究

针对目前普遍使用铝盐混凝剂而带来的饮用水中铝含量偏高的问题，首次提出了利用磁场与高分子絮凝剂协同强化絮凝降低铝含量的措施，为此进行了相关实验并进行了机理分析。     

复杂深埋地下高铁车站站台及通道空气动力学效应模拟及设计对策选定

针对京张高铁新八达岭隧道及地下车站的设计方案,采用数值计算软件,模拟地下车站屏蔽门和安全门两种模式下站台的最大风速、最大瞬变压力、压缩波峰值、人行通道最大风速等空气动力学效应进行计算分析。结果表明:无站台门时,车站中部会车使站内气动效应最不利,压力最大峰值可达508 Pa;设置屏蔽门时车站越行线位置的气动效应恶化,高速过站时在屏蔽门上产生的气动压力最大达到937 Pa,屏蔽门门口位置的最大风速值可达9.88 m/s;设置安全门时,到发线越行对站台风压作用小,站台风速低于5 m/s,站内人行通道风速可达7.5 m/s。八达岭地下车站采用安全门模式,站台风压和站内风速均可控制在安全范围内。     

考虑土-结构相互作用的能力谱法在铁路桥梁中的应用

在FEMA440考虑土-结构相互作用的能力谱法基础上,以客运专线双柱式桥墩为研究对象,选取与我国《铁路工程抗震规范》Ⅱ类场地相符合的80条强震记录,并以此得到具有统计意义的弹性反应谱;利用FEMA440改进等效线性化法对其进行修正,得到考虑土-结构相互作用的修正需求谱;进而利用FEMA440性能点轨迹法求解双柱式桥墩延性需求及性能点,并与80条强震记录非线性时程分析计算结果的平均值进行比较,验证将考虑土-结构相互作用的能力谱法应用于铁路桥梁工程抗震性能评估的可行性。     

内河架空直立式集装箱码头结构计算中的作用效应组合探讨

文章中采用单位力法对内河大水位差架空直立式集装箱码头可能出现的荷载工况进行了有限元计算，并采用MATLAB软件编程对计算结果进行分析组合，得到了计算结构各主要构件控制内力的最不利作用效应组合情况，提出了内河架空直立式集装箱码头结构计算的作用效应组合方法。     

Extreme-response analysis of jack-up platforms

The extreme wave and current response of a typical North Sea jack-up drilling platform has been calculated using nonlinear, stochastic, time-domain analysis techniques. A statistical treatment of the response-time histories has been performed. Appropriate probability distributions have been fitted to simulated response amplitudes and extrapolated to determine extreme values in storms of 3 or 6 h duration. Nonlinear geometric effects and dynamic effects are also addressed.

The results of the nonlinear time-domain analyses are compared to the results of more simplified methods used in jack-up designs.     

Effects of a hovering unmanned aerial vehicle on urban soundscapes perception

Several industry leaders and governmental agencies are currently investigating the use of Unmanned Aerial Vehicles (UAVs), or ‘drones’ as commonly known, for an ever-growing number of applications from blue light services to parcel delivery. For the specific case of the delivery sector, drones can alleviate road space usage and also lead to reductions in CO₂ and air pollution emissions, compared to traditional diesel-powered vehicles. However, due to their unconventional acoustic characteristics and operational manoeuvres, it is uncertain how communities will respond to drone operations. Noise has been suggested as a major barrier to public acceptance of drone operations in urban areas. In this paper, a series of audio-visual scenarios were created to investigate the effects of drone noise on the reported loudness, annoyance and pleasantness of seven different types of urban soundscapes. In soundscapes highly impacted by road traffic noise, the presence of drone noise lead to small changes in the perceived loudness, annoyance and pleasantness. In soundscapes with reduced road traffic noise, the participants reported a significantly higher perceived loudness and annoyance and a lower pleasantness with the presence of the same drone noise. For instance, the reported annoyance increased from 2.3 ± 0.8 (without drone noise) to 6.8 ± 0.3 (with drone noise), in an 11-point scale (0-not at all, 10-extremely). Based on these results, the concentration of drone operations along flight paths through busy roads might aid in the mitigation of the overall community noise impact caused by drones.     

近海结构疲劳计算中波浪与结构建模探讨

文章根据作者已提出的基于海况频度分布的统计分类及非线性动力学计算的疲劳评估方法,通过进一步改进波浪能的输入,提出了一种更为有效的计算方法。通过将这一方法运用到一典型导管架结构的疲劳计算,文中首先研究了波浪方向对疲劳破坏的影响,进而分析了波浪谱中若干重要参数及HHT-α时间积分中步长对疲劳计算结果的影响。通过对结构反应的统计研究,发现海况的恶劣程度并不直接影响结构响应非高斯趋势的显著程度。文中提出的方法在减少不确定性的同时又不降低安全标准,有效提高了疲劳计算的精确度,从而可以降低相关近海结构建设和维护成本。文中的计算方法已被成功地应用于北海及墨西哥湾数座近海结构在风和波浪荷载作用下的疲劳评估。     

Challenges in the application of spatial computable general equilibrium models for transport appraisal

The use of spatial computable general equilibrium (SCGE) models for assessing the economic impacts of transport projects is one of the key items on the research agenda for project appraisal in the Netherlands. These models are particularly suitable for analysing indirect effects of transport projects through linkages between the transport sector and the wider economy. Potentially, according to the literature, indirect effects that are additional to first-order direct cost reductions can turn out to be up to almost 80% in magnitude of the direct impacts. Given the relevance of these models for policy appraisal, experiences with this new modelling approach are important to report. After two years of development and application of SCGE models for transport appraisal, we found that the translation of theory behind the spatial equilibrium models into practical model specifications and empirical applications is a challenging task, and may lead to problems in project appraisal in terms of inaccuracies in the assessment of impacts. This paper discusses some key challenges we encountered with the specification of the Dutch SCGE model RAEM. This chapter is especially useful for researchers developing SCGE applications for use in transport appraisal and those who want to get a better understanding of differences between theoretical and computable SCGE modelling.     

建筑群下软~流塑地层隧道施工地表沉降控制分析

从南京地铁珠—鼓区间软~流塑地层隧道具体工程出发,根据既有地面建筑物基础允许变形的规范要求,建立了施工地表沉降控制基准,同时对隧道施工进行了动态模拟计算和分析,并通过施工现场监测结果,对所获得的成果进行了验证。