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211.
The Northern Sea Route (NSR) has tremendous potential for ocean shipping between Europe and Asia due to the savings from shorter transit time and distance. However, the Arctic area is environmentally vulnerable and thus there is a trade-off between NSR’s impacts on environment vs. its economic benefits, especially when compared with the traditional route, such as through the Suez Canal Route (SCR). This study estimates the market shares of different transport modes and alternative shipping routes for the container transport market between Europe and Asia, and the resulting environmental costs. Our result suggests that NSR can be a viable option under the status quo. However, its environmental costs tend to be higher than SCR due to small ship size and low load factor in the present, thus the development of NSR would lead to worse environment outcomes. If these issues can be resolved, NSR can benefit from lower operational and environmental costs, which will lead to higher market share and social welfare. Otherwise, increased use of NSR may lead to higher total environment costs than the status quo. 相似文献
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The district modified stiffness method (DMSM) considers the effect of joints and hand holes on the stiff-ness of the lining ring, assuming the stiffness around the joint and hand hole is to be reduced and the stiffness else-where is not changed. Considering the stiffness reduction of the lining ring caused by the segment’s circumferential joint, the internal force of the lining structure, the ground surface settlement and the displacement response of the surrounding soil body induced by shield driving are analyzed by an HS small strain constitutive model, and a 3D FEM model is established to analyze the interactions among the tunnel, soil body and building to apply to the dou-ble-line running tunnel of Shanghai Metro Line 11, which crosses under a historic building. In contrast, a 3D numeri-cal model based on the routine method (RMM) is set up and a comparison with the site measured data is conducted,with results indicating that they agree very well. The simulation results show that the existing building not only changes the surface settlement trough but also largely reduces horizontal displacement at the corresponding measuring points of the settlement trough; the distortion values of the existing building are related to the positions of the tunnel face and the location of the building; and the final distortion doesn’t decrease after completion of tunnel construction, but major residual distortion remains. This simulation method provides a reference for the control of disturbances during shield construction in soft rock. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
214.
努力节能降排,促进港口又好又快发展上海港"集装箱RTG高架滑触线供电方式油改电研制"等4个项目通过交通部鉴定" 总被引:2,自引:0,他引:2
2007年9月11日,由交通部科技教育司主持,在上海召开了"集装箱RTG高架滑触线供电方式油改电研制"等4个项目的鉴定会.科技教育司副司长张延华出席了鉴定会.会议由科技教育司副处长张杰主持.经过名专家认真评审,4个项目全部通过鉴定. 相似文献
215.
叙述了涡旋压缩机径向和轴向密封机理,设计并优化了径向柔性机构和密封条机构,提供了一种解决压缩腔内气体泄漏的途径。 相似文献
216.
海事执法督察是海事执法管理模式改革之后的新事物,因而探讨建立和完善海事执法督察制度显得尤为重要和紧迫,本文仅从海事执法督察含义、范围的界定、督察方法以及应当把握的原则等方面进行思考,希望有助于海事执法督察制度的真正建立和完善,以促进海事管理机构正确行驶职权,依法履行职责. 相似文献
217.
分析研究两列动车交会时周围的流场特性,对于减少列车交会过程的安全隐患非常重要。经过对列车交会时周围流场的模拟分析得出:其一,列车同向交会时其内侧压力较低,内外两侧会形成较大的压力差,列车的侧向力增加;其二,在列车反向交会过程中,车头相遇和车尾离开时,两列列车的阻力达到两个极大值点,升力在交会过程中先增加后减小,两列车并列瞬间升力值最大,侧向力在交会过程中不仅大小发生变化,而且还有一次方向的变化。所以,反向交会过程的安全隐患更多,应予足够重视。 相似文献
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219.
In a model commonly used in dynamic traffic assignment the link travel time for a vehicle entering a link at time t is taken as a function of the number of vehicles on the link at time t. In an alternative recently introduced model, the travel time for a vehicle entering a link at time t is taken as a function of an estimate of the flow in the immediate neighbourhood of the vehicle, averaged over the time the vehicle is traversing the link. Here we compare the solutions obtained from these two models when applied to various inflow profiles. We also divide the link into segments, apply each model sequentially to the segments and again compare the results. As the number of segments is increased, the discretisation refined to the continuous limit, the solutions from the two models converge to the same solution, which is the solution of the Lighthill, Whitham, Richards (LWR) model for traffic flow. We illustrate the results for different travel time functions and patterns of inflows to the link. In the numerical examples the solutions from the second of the two models are closer to the limit solutions. We also show that the models converge even when the link segments are not homogeneous, and introduce a correction scheme in the second model to compensate for an approximation error, hence improving the approximation to the LWR model. 相似文献
220.
管幕内顶进箱涵时顶部管幕力学作用的试验研究 总被引:2,自引:0,他引:2
上海市中环线虹许路北虹路下立交工程是目前世界上在饱和含水软土地层中施工的横截面最大的管幕法工程。为了充分研究箱涵顶进过程中管幕的力学作用,根据相似理论,按照实际工程状况进行了室内模型试验,得到了箱涵推进过程中地面和顶部管幕的竖向位移,以及管幕下土压力的变化特征,发现箱涵前端一定范围内的地层主要表现为竖向沉降变形,顶部管幕在箱涵推进过程中起到一定的承载作用,这对于稳定箱涵前端开挖面是有利的。试验结果对实际工程的设计与施工提供了一定的参考。 相似文献