各向异性对半圆形河谷散射影响的数值分析

半圆形河谷场地可构造为包含河谷的广义子结构和具有规则边界的开挖场地两部分,基于土-结构相互作用SSI原理,建立子结构控制方程。利用比例边界有限元SBFEM求解开挖场地动刚度,解析求解各向异性介质自由场qP波波动,将两者代入控制方程,可求得广义结构的动力响应。与文献中各向同性半空间中半圆形河谷在P波入射下的位移结果对比,验证了方法的精度和有效性。进一步分析了椭圆各向异性和非椭圆各向异性对半圆形河谷在qP波入射下位移分布的影响。数值算例显示,介质的各向异性改变了半圆形河谷散射位移的空间分布,增大了水平向位移的峰值;同时,介质的各向异性加剧了入射角对散射波场位移分布的影响。     

强震区城市地质灾害风险管理的研究内容与方法探讨

地质灾害风险管理是一种寻求更加合理有效的地质灾害减灾防灾的理念和模式。随着山区城市化进程的加快,经济和人口在城市的相对聚集,加之强烈地震活动,使得山区城市面临风险不断地提高。研究强震城市风险管理,已成为当前城市防灾减灾工作的一项重大课题。本文概述了国内外研究进展,提出该研究方向的主要研究内容和研究方法。未来研究内容应该包括（1）强震区城市地质灾害风险结构与风险量化分析,（2）城市地震地质灾害风险判据研究与风险准则建立,（3）强震区城市地质灾害管制的途径和方法研究,（4）强震区城市地质灾害管制的效能监控机制研究,（5）强震区城市地质灾害风险管制的模式与规范体系研究。     

Impact of phase out of leaded gasoline on the air quality in Budapest

As part of an air pollution study in Budapest, size-fractionated aerosol samples were collected by stacked filter units and cascade impactors, and some criteria pollutants and meteorological parameters were recorded in 1996, 1998 and 1999. The samplings were performed at three urban locations including an urban background site, a downtown site, and a tunnel. Elemental composition of the aerosol samples was measured by instrumental neutron activation analysis and/or particle-induced X-ray emission spectrometry; and black carbon (BC) was determined by a light reflectance technique. Since leaded gasoline was completely phased out in Hungary on 1 April 1999, the atmospheric concentrations of some typical transportation-related air pollutants (i.e. Pb, Br, BC and CO) were used for overviewing the actual impact of the phase out on the air quality and on the aerosol characteristics. For the background site, mean concentration of Pb and Br was not changed significantly. In the downtown site, the phase out resulted in a concentration decrease by a factor of 3–4 for Pb and Br. For the tunnel, concentrations of Pb and Br were decreased by a factor up to 9 and 28, respectively. Correlation between the pollutants, their crustal enrichment factors, and average elemental mass size distributions are also presented and discussed.     

不同产地积雪草中的微量元素比较研究

用火焰原子吸收分光光度法测定了７个不同产地的中药材积雪草中８种微量元素Ｆｅ、Ｃｕ、Ｃｕ、Ｚｎ、Ｍｎ、Ｃｏ、Ｃｄ、Ｓｒ、Ｃｒ的含量,并进行了比较,结果表明中药材中微量元素含量因地而异。为药材道 地性研究,药理作用探讨及临床用药提供了依据。     

Simulation study on ramp inflow for hybrid autonomous driving

In view of the complexity of the ramp traffic system on the expressway and the diversity of hybrid automatic driving, the safety distance of vehicles and the corresponding car following model are analyzed based on the combination of driver’s personality characteristics and the characteristics of different automatic driving levels of the vehicle–road​ coordination system, and the risk model is established to screen the potentially dangerous vehicles in the ramp merging process. Based on game theory, this paper constructs a ramp coordination and merging control model suitable for hybrid automatic driving. The model takes the safety benefit and efficiency benefit as the objective function, predicts the benefit value under different strategies and makes the optimal strategy under the current conditions. The proposed model is verified by the joint simulation of Python and sumo. the simulation results show that the average number of combined vehicles is 1.91 times higher, the combined position is 50.11% earlier and the average driving time is 28.35% less than that without control strategy and there is obvious advantage when the density is high compared with vehicles without control strategy.     

Species-Related Difference to Noise Reduction Between Trees in Urban Forest: The Abidar Forest Park (Case Study)

Sound pollution is one of the most important urban problems which endangers mental and physical health of the residents. This study was aimed to assess the influence of different tree species, including Fraxinus rotundifolia, Robinia pseudoacacia, Platanus orientalis, Platycladus orientalis, and Pinus eldarica, in reducing noise pollution in the Abidar Forest Park. A further objective was to identify the contaminated areas of Sanandaj city and to propose suitable noise absorbent tree species in consistent conditions. For each tree stands the noise measurements were performed during intervals at frequencies of 250, 500 and 1000 Hz, besides an open area with the same topography. With regards to the second purpose, a total of 50 stations with residential, commercial, residentialcommercial, and green space applications were selected across the city. Equivalent Continuous Sound Pressure Level (Leq) was determined in five replicates for 30 min. The measurements were performed under stable weather conditions and low wind velocity at 17:00 (traffic peak) in summer and fall. All of the Leq values were above the threshold noise level. The highest noise reduction was recorded in summer (i.e., green season); Platanus and Platycladus species demonstrated the highest and lowest noise absorption (31.43 dB and 22.28 dB, respectively). Furthermore, a meaningful difference was observed between Leq values of commercial, residential, commercial-residential, and green space urban applications, and the central parts of the city showed noticeable noise pollution. Taken together, due to being exposed to higher than the acceptable threshold noise level, the residents of Sanandaj will be endangered to health problems in the near future; thus consideration should be given to the noise pollution sources.     

Cellular automata simulation of traffic including cars and bicycles

As ‘greening’ of all aspects of human activity becomes mainstream, transportation science is also increasingly focused around sustainability. Modal co-existence between motorised and non-motorised traffic on urban networks is, in this context, of particular interest for traffic flow modelling. The main modelling problems here are posed by the heterogeneity of vehicles, including size and dynamics, and by the complex interactions at intersections. Herein we address these with a novel technique, based on one-dimensional cellular automata components, for modelling network infrastructure and its occupancy by vehicles. We use this modelling approach, together with a corresponding vehicle behaviour model, to simulate combined car and bicycle traffic for two elemental scenarios—examples of components that would be used in the building of an arbitrary network. Results of simulations performed on these scenarios, (i) a stretch of road and (ii) an intersection causing conflict between cars and bicycles sharing a lane, are presented and analysed.     

Space evolution model and empirical analysis of an urban public transport network

This study explores the space evolution of an urban public transport network, using empirical evidence and a simulation model validated on that data. Public transport patterns primarily depend on traffic spatial-distribution, demands of passengers and expected utility of investors. Evolution is an iterative process of satisfying the needs of passengers and investors based on a given traffic spatial-distribution. The temporal change of urban public transport network is evaluated both using topological measures and spatial ones. The simulation model is validated using empirical data from nine big cities in China. Statistical analyses on topological and spatial attributes suggest that an evolution network with traffic demands characterized by power-law numerical values which distribute in a mode of concentric circles tallies well with these nine cities.     

Networked characteristics of the urban rail transit networks

Urban rail transit networks (URTNs) have experienced rapid development and have been receiving much attention recently. In this paper, we comprehensively analyze the topological characteristics of urban rail transit networks, and we find that the average degrees of nodes of urban rail transit networks lie in the interval [2, 2.45], most of the average shortest path lengths between pairs of nodes belong to the interval [10, 16] and the average betweenness of nodes and edges linearly increase with the increase of the number of stations. Moreover, the cumulative probability distributions of the degree and shortest path length can be fitted by exponential distribution and Gauss distribution, respectively. The network failures of the urban rail transit networks are discussed and we also discover that the highest betweenness node-based attack is the most effective method to destroy the network.     

基于传感器网络的广域噪声监测技术

设计了一种针对城市环境噪声的广域噪声传感器网络系统,采用微型前置放大器和数字化网络采集仪组成检测系统,完成噪声信号的接收和采集,并通过软件设计完成采集的噪声信号存储、分析、显示及处理,实现了对噪声分布的图像化展示。