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随着中国城市群的快速发展,城际交通出行环境发生了巨大的变化,因此城际出行者也会不断地重建自己的出行习惯,这就要求建立动态模型研究城际出行者出行行为和预测城际交通需求。本文调查出行者在宁杭城际高铁开通前后两个时期的出行信息,并且引入状态依赖变量表征出行者之前选择结果对之后出行选择的影响,建立了基于面板数据的城际出行方式选择动态模型。模型结果表明,基于面板数据的动态模型比传统的基于出行者单次出行数据的模型拥有更高精度。同时本文根据宁杭城际出行背景设置三组政策变化方案预测出行分担率,结果表明,当选择环境发生变化时,传统模型会高估出行方式分担率的变化程度。以上结论能更好地服务于中国城际交通的规划。     

基于城市轨道交通客流短时预测的运营编组设计

根据城市轨道交通客流短时预测量进行运营编组设计,更接近客流的实际运营情况,具有实时、灵活和快速响应等优点.以一周为周期,使用最近一周的历史断面客流量作为原始数据,应用嵌入式灰色神经网络组合模型进行短时预测,得到的下一周期断面客流量更符合客流不断变化的趋势.以此为基础进行运营编组设计,使其更能适应客流量的实时变化.然后将按计划运营的实际客流纳入历史客流,进行循环修正更新,作为下一周期客流短时预测基础进行运营编组设计.基于城市轨道交通客流短时预测的运营编组优化,在一定程度上可以提高城市轨道交通系统运能,提升运营效率,降低运营成本.     

广州市与世界级城市交通模式辨析

中国城市常借鉴国外发展经验来制定城市交通战略,但缺乏对国内外城市交通特征的准确辨析。城市交通特征应反映主动出行者与被动出行者的区别。首先比较广州市与世界级城市的出行方式构成和出行特点,指出广州市的公共交通出行者大多为无驾驶执照或未购置小汽车的人群。针对公共交通出行分担率单一指标的弊端,引入公共交通出行指数与机动化水平来表征城市公共交通发展程度。评价广州市及世界级城市公共交通发展水平,并据此划分9类交通模式。结果显示,广州市公共交通服务水平和机动化水平均处于初级阶段。最后,分析广州市交通模式升级转型的最佳路线及实施策略,指出公共交通出行分担率与机动化水平的矛盾与协调是制定交通发展战略时需要考虑的关键所在。     

基于多种失效模式SPS复合钢板替换船用钢板的优化设计

在SPS复合钢板的设计中获取不同的失效模式。以减重为目标,应用序列二次规划法对SPS复合钢板进行等效船用钢板的优化设计,同时对SPS复合钢板进行多目标优化,应用层次分析法定各目标的权重。在这两种优化方法的基础上,对船用钢板与SPS复合钢板进行了屈曲、弯曲对比数值分析,同时将结果与理论计算结果对比分析。结果表明,SPS复合钢板重量能够减轻37%以上,刚度增加两倍多,但厚度增加70%。     

响应谱法与时程法在管道水锤分析中的对比研究

水锤是输流管道中经常发生的现象,由于阀门操作不当或设备突然停车引起的水锤极易引起管道的振动,造成设备及支架的破坏,严重影响管道系统的正常运行。文章运用CAESAERⅡ软件,对管道中的水锤现象分别采用响应谱法和时程分析法进行分析。结果表明:响应谱法有利于对振动响应过大模态的精确控制,时程法能精确求解时间历程内各时刻系统的整体响应。为全面分析水锤对管道应力的影响提供了一个研究思路。     

一种紧凑的圆波导 TE01模式激励器

提出了一种基于微带结构的K波段圆波导 T E01模式的激励器。该激励器由四个微带贴片单元环形排列组成,通过设计合理的馈电网络实现TE01模式的辐射。运用 HFSS电磁仿真工具分析了该激励器在圆波导中对TE01模式电磁波的激励情况,并设计了一个微波传输损耗测量实验来验证T E01模式激励的有效性。     

大口径舰炮制导炮弹装填方式

介绍制导炮弹发展及其典型结构,对国内外制导炮弹在大口径舰炮上的应用进行介绍,并根据大口径舰炮使用制导炮弹的特殊性,对分装式制导炮弹的装填方式进行探讨,从易装性、安全性、对射速的影响以及多弹种兼容性等方面进行优劣分析,并提出几种可行性建议。     

The effect of attitudes toward cars and public transportation on behavioral intention in commuting mode choice—A comparison across six Asian countries

This study investigated the contribution of psychological factors in explaining the choice of transportation mode in six Asian countries. Data were collected from 1118 respondents in Japan, Thailand, China, Vietnam, Indonesia, and the Philippines. The dependent variable was the intention to use one of three modes for work travel after getting a job: car, public transit, or other modes. The explanatory variables were three attitude factors taken from a previous study, including: 1/symbolic affective, reflecting affective motives of travel mode use; 2/instrumental, referring to functional attributes of travel modes; and 3/social orderliness which represents for environmental friendliness, safety, altruism, quietness et cetera. Several logit model estimates were made using the samples from the six countries separately and together. We obtained three main findings. First, attitude variables about the car were all significant determinants for the entire sample from Asian countries. Second, the social orderliness aspect of public transit was a common concern of respondents from developing countries in selecting this mode for work trips. Third, in countries in which the intent to use a car was not very high, attitude factors about the car were found to be significant determinants of the behavioral intention to commute by car but were less significant in countries in which the desire to use a car was high.     

悬浮结构铁路信号设备雷击损坏的原因分析及防护方法探讨

很多铁路信号系统,特别是轨道电路的发送、接收和CAN总线均采用悬浮结构。为了防止出现第三轨问题,雷电防护方案中只加装差模(横向)防护用SPD,共模(纵向)防护是靠系统绝缘特性来承担。可是在实际应用中出现雷击损坏现象多是因为缺少共模防护。通过科研试验数据和现场雷害调查结果,综合分析该类悬浮系统共模雷击损坏特点,并针对防止出现第三轨问题,提出新的共模雷电防护方案供大家参考。     

Experimental and finite element analysis of fatigue strength for 300 mm2 copper power conductor

The fatigue strength of a 300 mm² stranded copper conductor was investigated experimentally and by finite element (FE) analysis. An analytical model was also developed and validated. Wires taken from the outer layer of the conductor were fatigue tested in tension–tension loading and compared with similar data for wires taken from a 95 mm² conductor. The wire cross section was deformed due to the compacting process that was applied during fabrication. When corrected for stress concentrations due to the deformation the data for the two sets of wire fell within the same scatter-band. Full scale testing was carried out in a specially designed rig with constant tensile load and reversed displacement controlled bending with a fixed curvature variation. The loading is a simulation of the loading of a power cable hanging from a floating vessel through a bellmouth. Conductors were tested in two states; dry and lubricated. A finite element model was established for the copper conductor. The model was formulated by a combination of elastic beam and beam-contact elements that included the effects of friction. The effect of local bending due to contact forces was included in the model. Two contact conditions were investigated; the point (trellis) contact between adjacent layers of wire and the inline contact within each layer and between the first layer (centre wire) and the second layer. The FE model was validated by a calibration test of a full scale conductor, and by sensitivity studies varying the size and the number of elements of the model. Fatigue analysis of the conductor was carried out, based on the S–N curve for individual wires. Taking into account the effects of friction and local bending, agreement was obtained between predicted and experimental fatigue strength of the conductor, for the FE model as well as the analytical model.