基于区域数值模拟的抗浮水位研究--以石家庄地铁1号线二期为例

抗浮水位的取值对工程安全和工程造价影响巨大。以石家庄地铁1号线二期为例,在充分分析区域水文地质条件的基础上,通过GMS软件中的modflow模块并依据水均衡分析参数进行建模。基于校正后的模型,综合考虑各种不利因素(尤其是南水北调和黄壁庄水库泄洪对地下水位的影响),预测得出各车站最高地下水位为51.2~56.0 m。模型预测结果显示,由于距离滹沱河较近,东庄站、西庄站地下水位在极端降雨当年就出现大幅抬升;东上泽站、东洋站位于农业开采区且距离滹沱河以及城市集中开采区相对较远,将在极端降雨的第二年出现最高水位。最后,根据结构与含水层关系,确定了各车站的基底浮力压强为0~70 kPa。     

长三角民航协同规划的上海实践

推进长三角交通一体化规划落地是实施国家长三角一体化发展战略的重要基础。通过系统梳理上海多年空间规划实践经验,遵循城市群、机场群、近沪地区、全球城市多机场体系的逻辑思路,基于问题导向和目标导向,提出优先实现近沪地区民航紧密联系的规划突破点。临近地区民航协同,需要实现发展目标、通道枢纽、飞行保障、运输服务、货运物流、设施建设、重大项目、进度时序等多方面系统协同,建立契约关系,以市场化方式实践区域民航协同发展。     

区域性交通影响评价阈值的确定方法

新改扩建项目交通影响评价协调了交通需求与交通供给之间的关系,但单体建设项目的交通影响评价方法对于协调城市中某一区域的交通往往带来诸多利益主体平衡的困难,导致交通影响评价的效果不理想.为此,在城市快速发展时期,需要建立侧重于较大范围的区域性交通影响评价方法.针对区域性交通影响评价中范围阈值的确定,提出了标准区域类比法,研究了标准区域的确定方法和阈值确定的过程,并结合北京某区域实际,进行了区域确定方法的案例研究.     

Regional climate impact of aerosols emitted by transportation modes and potential effects of policies on demand and emissions

The transportation system is one of the main sectors with significant climate impact. In the U.S. it is the second main emitter of carbon dioxide. Its impact in terms of emission of carbon dioxide is well recognized. But a number of aerosol species have a non-negligible impact. The radiative forcing due to these species needs to be quantified. A radiative transfer code is used. Remote sensing data is retrieved to characterize different regions. The radiative forcing efficiency for black carbon are 396 ± 200 W/m²/AOD for the ground mode and 531 ± 190 W/m²/AOD for the air transportation, under clear sky conditions. The radiative forcing due to contrail is 0.14 ± 0.06 W/m² per percent coverage. Based on the forcing from the different species emitted by each mode of transportation, policies may be envisioned. These policies may affect demand and emissions of different modes of transportation. Demand and fleet models are used to quantify these interdependencies. Depending on the fuel price of each mode, mode shifts and overall demand reduction occur, and more fuel efficient vehicles are introduced in the fleet at a faster rate. With the introduction of more fuel efficient vehicles, the effect of fuel price on demand is attenuated. An increase in fuel price of 50 cents per gallon, scaled based on the radiative forcing of each mode, results in up to 5% reduction in emissions and 6% reduction in radiative forcing. With technologies, significant reduction in climate impact may be achieved.     

自适应步长的细菌觅食优化算法研究

细菌觅食优化算法是一种群集智能优化算法,该文详细分析了细菌觅食优化算法中最重要的趋向性操作,其中步长对算法的效率和精度有很大影响;根据菌群中细菌个体间的位置信息,设计了动态步长估值函数,自适应的调整步长.通过经典函数的测试,说明改进细菌觅食优化算法在收敛速度和精度上比原有算法有极大提高.     

Matching biological traits to environmental conditions in marine benthic ecosystems

The effects of variability in environmental conditions on species composition in benthic ecosystems are well established, but relatively little is known about how environmental variability relates to ecosystem functioning. Benthic invertebrate assemblages are heavily involved in the maintenance of ecological processes and investigation of the biological characteristics (traits) expressed in these assemblages can provide information about some aspects of functioning. The aim of this study was to establish and explore relationships between environmental variability and biological traits expressed in megafauna assemblages in two UK regions. Patterns of trait composition were matched to environmental conditions and subsets of variables best describing these patterns determined. The nature of the relationships were subsequently examined at two separate scales, both between and within the regions studied. Over the whole area, some traits related to size, longevity, reproduction, mobility, flexibility, feeding method, sociability and living habit were negatively correlated with salinity, sea surface temperature, annual temperature range and the level of fishing effort, and positively associated with fish taxon richness and shell content of the substratum. Between the two regions, reductions in temperature range and shell content were associated with infrequent relative occurrences of short-lived, moderately mobile, flexible, solitary, opportunistic, permanent-burrow dwelling fauna and those exhibiting reproductive strategies based on benthic development. Relationships between some traits and environmental conditions diverged within the two regions, with increases in fishing effort and shell content of the substratum being associated with low frequencies of occurrence of moderately mobile and moderately to highly flexible fauna within one region, but high frequencies in the other. These changes in trait composition have implications for ecosystem processes, with, for example, reductions in permanent-burrow dwellers within one of the regions potentially compromising the ability of the assemblages to process and store chemicals and waste products. However, the connections between environmental conditions and trait composition are complex and incorporate many factors. Experimental investigations will be necessary to determine the extent and consequences of these important relationships.     

经济中心城市机场轨道交通规划研究——国外经验与深圳实践

首先,论述经济中心城市发展与机场发展之间相互需要、相互促进的关系;然后,通过分析巴黎戴高乐机场与法兰克福机场轨道交通发展的案例,对机场轨道交通规划经验进行总结借鉴;最后,结合深圳城市发展和机场发展的实际,对深圳机场轨道交通布局提出相应建议。     

广佛同城化区域交通一体化规划实践

文章分析了广州、佛山两市同城化区域交通存在的问题,探讨了交通一体化战略目标及发展策略;同时通过结合城市群交通规划特点及实践,提出了城市群交通一体化规划的一般方法,对今后城市群交通一体化规划开展更深入的研究提出了相关建议。     

准移动闭塞系统针对市域快线的适用性分析

针对国内城市轨道交通中被广泛采用的准移动闭塞系统,对市域快线的运营速度、站间距、牵引供电方式等进行分析,从理论上说明基于数字轨道电路的准移动闭塞信号系统可以满足市域快线的要求。     

枢纽内区域计算机联锁系统构成方案

简要介绍区域计算机联锁系统在枢纽型大站场应用现状,分析枢纽内区域计算机联锁系统的结构,并对其进行优缺点对照。