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21.
This primary objective of this paper is to examine the causes for the change in energy consumption in the transport sector in India. The pattern of energy consumption and their causes for change are benchmarked against select countries. A mathematical model that decomposes changes in energy consumption to various factors has been used. The changes in the energy consumption are attributed to growth in transport volume, structural change or modal shift, and energy intensity. The analysis is conducted for passenger and freight transport separately. Results indicate that the growth in transport volume has been the main cause for increase in energy consumption for both passenger and freight transport in India despite the decline in energy intensity of various transport modes. Though not surprising for a growing economy like India, this poses a challenge for the future. Currently, India is a low carbon economy. 相似文献
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韩江北桥主桥力学性能分析 总被引:1,自引:0,他引:1
应用大型有限元程序MIDAS/Civil,建立了韩江北桥主桥整体的空间有限元计算模型,根据钢管混凝土统一理论计算了各桥跨拱肋单元的截面特性,采用刚度、质量等效原则对复杂桥面板进行了简化模拟。依据桥梁设计规范要求对该桥梁成桥阶段的静力性能进行了详细计算。计算结果表明,当桥梁某跨上布置有汽车荷载时,其余各桥跨是否布置有汽车荷载,对该桥跨竖拱拱肋及桥面系横梁内力、变形结果影响较小。因此,在桥梁设计计算中,可大大减少作用效应组合的数量,在进行桥梁整体性能计算做作用效应最不利组合时,为简化设计计算,可仅考虑汽车荷载沿全桥各桥跨布置这一种典型情况参与组合即可计算得到足够精确的计算结果。本文计算结果已为韩江北桥主桥设计提供依据,并对同类桥梁结构设计也具有重要的参考价值。 相似文献
24.
根据一座单箱三室连续刚构组合桥梁,考虑桩-土相互作用分别建立了变截面三维梁单元和三维实体、板壳单元组合两种有限元模型,分析了桥梁在均布荷载和集中荷载作用下的剪力滞效应,并讨论了两种计算模型对动力特性的影响。结果表明,在均布荷载与集中荷载作用下箱梁的剪力滞效应明显不同,对于地震时程反应分析而言,采用变截面三维梁单元模型计算效率较高。所得的分析结果对指导这类桥梁的设计具有重要的工程实用价值。 相似文献
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首先对新型废料——增钙渣和增钙粉煤灰进行了物理化学性能分析,证明其活性优于普通混凝土。采用正交试验方法对双掺该材料的水泥混凝土的力学强度试验结果进行了极差和方差分析,得出了影响强度性能的因素。采用快冻法等规定的试验方法验证了双掺混凝土的抗冻、收缩、抗磨耗等路用耐久性能。对双掺混凝土的强度和耐久性机理进行了级配调整、改善界面性能、孔结构等3方面的理论分析。对比试验结果表明:双掺增钙渣、增钙灰混凝土的抗压、抗折强度、抗折弹性模量等力学指标达到重交通等级公路要求,抗冻性能、收缩性能与普通砂混凝土相当,抗磨耗性能超过了普通砂混凝土,证明双掺此种材料的水泥混凝土可以满足公路建设的需要,而且还可以减少环境污染,社会意义重大。 相似文献
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交通基础设施建设投资对国民经济拉动作用的定量分析 总被引:11,自引:0,他引:11
运用投入产出模型定量分析了公路交通基础设施建设投资对国民经济的拉动作用。拉动作用主要表现为公路建设投资所产生的直接、间接和诱导经济效益,其总和为公路建设投资的乘数效应,可分别用产出乘数、GDP乘数和就业乘数来测算。分析测算了我国近年来公路建设投资对国民经济的拉动作用。估算结果表明,(1)公路建筑业对其他部门的波及影响程度大于各部门的平均影响水平;(2)拉动作用在1998年最为显著,自1999年开始,公路投资拉动经济增长的百分比呈逐年上升的趋势。 相似文献
28.
We analyse mode choice behaviour for suburban trips in the Grand Canary island using mixed revealed preference (RP)/stated
preference (SP) information. The SP choice experiment allowed for interactions among the main policy variables: travel cost,
travel time and frequency, and also to test the influence of latent variables such as comfort. It also led to discuss additional
requirements on the size and sign of the estimated model parameters, to assess model quality when interactions are present.
The RP survey produced data on actual trip behaviour and was used to adapt the SP choice experiment. During the specification
searches we detected the presence of income effect and were able to derive willingness-to-pay measures, such as the subjective
value of time, which varied among individuals. We also studied the systematic heterogeneity in individual tastes through the
specification of models allowing for interactions between level-of-service and socio-economic variables. We concluded examining
the sensitivity of travellers’ behaviour to various policy scenarios. In particular, it seems that contrary to political opinion,
in a crowded island policies penalising the use of the private car seem to have a far greater impact in terms of bus patronage
than policies implying direct improvements to the public transport service. 相似文献
29.
Markets for transport are often characterised by unequal demand in both directions: every morning during peak hours the trains are crowded while moving towards the direction of large cities, whereas they may be almost empty in the other direction. In this paper we discuss the implications of these imbalances for price setting of transport firms. From the viewpoint of economic theory, two regimes can be distinguished: one where – owing to price discrimination – the flows are equal, and one where unequal flows are the result. Special attention is paid to the case where the transport firm does not apply price discrimination, as is the case with most railway firms in Europe. We find that in the case of substantial joint costs, the introduction of price discrimination not only leads to an increase of profits, but also to positive effects on consumer surplus. This result differs from the standard result in the literature on industrial economics. The standard result purports that with linear demand functions price discrimination has a negative impact on the welfare of the average consumer and that this negative impact dominates the positive effect on profits of the producer. 相似文献
30.