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381.
本文论述电气化铁道供电系统优化设计的新课题。在建立牵引仿真(或牵引计算)数据库基础上,应用数学规划方法提出了寻优设计的两个数学模型:最小能损模型和最少工程费用模型,并详细讨论了以最小能损为目标函数的数学模型及算法。给出的算例表明,按寻优设计方案能有效地减少整个牵引供电系统中的功率损失(能量损失)。 相似文献
382.
Gaspar L. Gil Gómez Alexander Lönnergård Mohit H. Asher Mikael Nybacka Egbert Bakker Lars Drugge 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2017,55(7):945-969
Objective testing of vehicle handling in winter conditions has not been implemented yet because of its low repeatability and its low signal-to-noise ratio. Enabling this testing, by identifying robust manoeuvres and metrics, was the aim of this study. This has been achieved by using both experimental data, gathered with steering-robot tests on ice, and simulation models of different complexities. Simple bicycle models with brush and MF-tyre models were built, both optimally parameterised against the experimental data. The brush model presented a better balance in complexity performance. This model was also implemented in a Kalman filter to reduce measurement noise; however, a simpler low-pass filter showed almost similar results at lower cost. A more advanced full vehicle model was built in VI-CarRealTime, based on kinematics and compliance data, damper measurements, and real tyre measurements in winter conditions. This model offered better results and was therefore chosen to optimise the initial manoeuvres through test design and simulations. A sensitivity analysis (ANOVA) of the experimental data allowed one to classify the robustness of the metrics. Finally, to validate the results, the proposed and the initial manoeuvres were tested back to back in a new winter campaign. 相似文献
383.
特大型桥梁群桩基础承载特性离心模型试验研究 总被引:2,自引:0,他引:2
苏通大桥超大型主桥索塔群桩基础置于第四系土层中,其承载变形特性是设计急待解决的技术问题。通过离心模型试验,研究了5种工况下主桥索塔群桩基础的竖向承载变形特性,分析了承台竣工、裸塔竣工、成桥阶段群桩基础的沉降及桩顶荷载分布规律。结果表明,5种工况下主桥索塔群桩基础的极限承载力大于5 000 MN,成桥阶段的总沉降为148~186 mm,基础整体稳定,桩顶荷载成W形分布,桩底注浆和冲刷形态对群桩基础的承载变形特性有一定影响。 相似文献
384.
385.
Estimation of the determinants of bicycle mode share for the journey to work using census data 总被引:1,自引:0,他引:1
A model is presented that relates the proportion of bicycle journeys to work for English and Welsh electoral wards to relevant
socio-economic, transport and physical variables. A number of previous studies have exploited existing disaggregate data sets.
This study uses UK 2001 census data, is based on a logistic regression model and provides complementary evidence based on
aggregate data for the determinants of cycle choice. It suggests a saturation level for bicycle use of 43%. Smaller proportions
cycle in wards with more females and higher car ownership. The physical condition of the highway, rainfall and temperature
each have an effect on the proportion that cycles to work, but the most significant physical variable is hilliness. The proportion
of bicycle route that is off-road is shown to be significant, although it displays a low elasticity (+0.049) and this contrasts
with more significant changes usually forecast by models constructed from stated preference based data. Forecasting shows
the trend in car ownership has a significant effect on cycle use and offsets the positive effect of the provision of off-road
routes for cycle traffic but only in districts that are moderately hilly or hilly. The provision of infrastructure alone appears
insufficient to engender higher levels of cycling.
John Parkin joined academia after a career in consultancy. He has experience of all stages of the promotion of transport infrastructure, from planning and modelling to design and implementation. His specialises in transport engineering with an emphasis on design innovation, sustainability principles and community benefit. Mark Wardman has been involved in transport research for over 20 years. His main research interests are in behavioural response models in general and stated preference in particular. Areas of application have included public transport, notably rail, with several novel applications to cycling and environmental issues. Matthew Page research interests include transport policy and how it has developed, the environmental impacts of transport, the impacts of transport on climate change, and walking and cycling. 相似文献
Matthew PageEmail: |
John Parkin joined academia after a career in consultancy. He has experience of all stages of the promotion of transport infrastructure, from planning and modelling to design and implementation. His specialises in transport engineering with an emphasis on design innovation, sustainability principles and community benefit. Mark Wardman has been involved in transport research for over 20 years. His main research interests are in behavioural response models in general and stated preference in particular. Areas of application have included public transport, notably rail, with several novel applications to cycling and environmental issues. Matthew Page research interests include transport policy and how it has developed, the environmental impacts of transport, the impacts of transport on climate change, and walking and cycling. 相似文献
386.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(6):701-720
Vehicle rollover represents a significant percentage of single-vehicle accidents and accounts for over 9000 fatalities and over 200,000 non-fatal injuries each year. Previous research has yielded rollover stability control systems that are effective in on-road conditions. Accident statistics show, however, that over 90% of rollovers involve road departure, during which a vehicle may encounter sloped and rough terrain while travelling at high speed. A critical element of most rollover stability control systems is a metric that monitors a vehicle's nearness to rollover. Most metrics, however, are designed for use on flat, level surfaces characteristic of on-road terrain. In this paper, a new stability metric, termed the stability moment, is proposed that is accurate on terrain surfaces with arbitrary geometry, which allows it to be used in road departure scenarios. The metric is based on an estimate of the distribution of wheel–terrain contact forces. The metric can be calculated on line in real time, using only practical, low-cost sensors. The metric is compared in simulations and experimental studies to existing stability metrics and is shown to exhibit superior performance, particularly in off-road conditions. 相似文献
387.
剪纸艺术之审美意蕴及其在现代平面设计的运用 总被引:1,自引:0,他引:1
张瑞云 《兰州交通大学学报》2011,(2)
剪纸艺术是一株灿烂的民族艺术之花,是活态的生活文化史,具有深厚而丰赡的审美意蕴。文章通过分析剪纸艺术的风格特征,将其与现代平面设计相结合。重点从传统与现代、传承与创新、图形与设计三个方面,论述了剪纸艺术在现代平面设计中的新理念。通过实例分析可知,二者的巧妙结合,是借鉴其形式特点,保留其形式遗风,借用、延伸其寓意,并结合现代设计理念和表现手法,对其进行再设计,赋予其时代气息和新的生命力。 相似文献
388.
389.
为研究盾构隧道施工对富水软弱底层的扰动影响,以大连地铁某标段盾构隧道施工为例,首先基于修正剑桥模型建立土体本构关系,利用Shell结构单元模拟盾构初衬;然后采用流固耦合方法研究土体固结过程对盾构开挖引起软弱地层扰动问题;最后根据仿真结果与现场实测数据,绘制地表沉降对比分析曲线,给出盾构施工引起地表沉降的动态变化趋势.结果表明:孔隙水在盾构开挖完成后仍持续向隧道方向渗透,并引起距隧道较近区域的扰动趋势大于周围较远区域.本研究对提高富水软弱地层条件下盾构施工过程建模的准确性和实效性、指导盾构施工具有指导作用. 相似文献
390.
邰茜 《筑路机械与施工机械化》2012,29(4):86-88
以反转六连杆轮式装载机ZL50G为样机,运用ADAMS软件建立样机的三维实体模型,对轮式装载机的工作装置进行动态载荷分析,为轮式装载机工作装置的研究提供一种可靠的方法.分析结果为轮式装载机工作装置的设计与优化提供了理论依据. 相似文献