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1.
Takafumi Kawamura Hideaki Miyata Kohji Mashimo 《Journal of Marine Science and Technology》1997,2(4):245-256
A time-marching CFD simulation is performed for self-propelling ships. The flow about the hull is simulated by the finite-volume
method, and the propeller action is approximated as a propeller disk for which the solution is given by a simplified propeller
model. The interaction of two flow models is treated in a time-marching procedure converging towards the steady self-propelling
condition. This method is applied to five tanker models, and detailed comparisons are made between the simulated results and
corresponding experimental results. It is shown that the flow field in the self-propelling condition is qualitatively well
reproduced in the simulation, and the estimated thrust deduction factors for the five hull forms agree well with measured
ones. However, the effective wake factors are underestimated, since the Reynolds number in the simulations differs from that
in the experiment. 相似文献
2.
沪杭磁浮线对长江三角洲的经济将会带来巨大影响,同时其投入资金巨大.从可量化效益(节约乘客出行时间、提高安全性、提高乘客的劳动生产率、节约城市土地、降低污染、带动沿线不动产的增值、节约能源)和不可量化效益(改善交通促进城市发展、改善居民生活质量)这两大方面对沪杭磁浮线的社会经济效益进行分析. 相似文献
3.
采用新型钢轨焊缝保护装置后钢轨焊缝处的轮轨动力学特性 总被引:1,自引:0,他引:1
根据轮轨相互作用机理,建立安装新型钢轨焊缝保护装置后钢轨焊缝处的车辆—轨道耦合动力学模型,对此处的轮轨垂向力、脱轨系数、轮重减载率等轮轨动力学指标进行仿真计算,并分别与采用鼓包鱼尾板和没有焊缝保护装置时进行对比,研究采用新型钢轨焊缝保护装置时焊缝处的轮轨动力学特性。对比分析结果表明:采用新型钢轨焊缝保护装置后,轮轨垂向力降幅分别为1.28%和4.63%,脱轨系数降幅分别为1.49%和2.94%,轮重减载率降幅分别为3.41%和7.68%;新型钢轨焊缝保护装置在各速度条件下均能够有效地减小焊缝振动和动态受力。由此可见,采用新型钢轨焊缝保护装置,可消除打螺栓孔带来的安全隐患,有效减小焊缝处的动力响应,加强焊缝处的轨道结构整体性。现场动态测试结果进一步验证了新型钢轨焊缝保护装置结构的合理性。 相似文献
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5.
柔性桩与土相互作用非线性分析的增量传递矩阵法 总被引:1,自引:3,他引:1
对桩侧土采用非线性荷载传递函数,对桩端土采用线性荷载传递函数,同时考虑桩周土所分担的荷载对单桩荷载传递规律的影响,利用增量荷载传递矩阵法及微分方程的近似解法--子域法,推出了刚性承台下柔性桩与地基非线性相互作用的近似解析算式。为了验证该方法的可行性,通过试验将试验结果与有限元结果及该方法所得结果进行了对比,对比表明:该理论解与现场实测值、有限元计算值都非常接近。 相似文献
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8.
在体验经济时代(在消费过程中追求顾客满意、注重自我体验),新能源汽车作为汽车行业的新兴产业,不断受到人们的追捧,其内饰比外观更为重要。在新能源汽车的内饰中,许多零部件具有不可替代的互动性,这也是用户了解新能源汽车内饰的关键因素之一。在智能化时代的背景下,大多数新能源汽车制造商单纯地将智能技术应用到新能源汽车上,其内饰造型、人机交互和使用体验已经不能满足客户对新能源汽车的要求。人机工程学是新能源汽车内饰设计的出发点,掌握用户形象认知是新能源汽车内饰设计的关键。因此,本文从用户的认知角度来研究新能源汽车的内饰设计与创新。 相似文献
9.
This study determines the optimal electric driving range of plug-in hybrid electric vehicles (PHEVs) that minimizes the daily cost borne by the society when using this technology. An optimization framework is developed and applied to datasets representing the US market. Results indicate that the optimal range is 16 miles with an average social cost of $3.19 per day when exclusively charging at home, compared to $3.27 per day of driving a conventional vehicle. The optimal range is found to be sensitive to the cost of battery packs and the price of gasoline. When workplace charging is available, the optimal electric driving range surprisingly increases from 16 to 22 miles, as larger batteries would allow drivers to better take advantage of the charging opportunities to achieve longer electrified travel distances, yielding social cost savings. If workplace charging is available, the optimal density is to deploy a workplace charger for every 3.66 vehicles. Moreover, the diversification of the battery size, i.e., introducing a pair and triple of electric driving ranges to the market, could further decrease the average societal cost per PHEV by 7.45% and 11.5% respectively. 相似文献
10.
Reliable travel behavior data is a prerequisite for transportation planning process. In large tourism dependent cities, tourists are the most dynamic population group whose size and travel choices remain unknown to planners. Traditional travel surveys generally observe resident travel behavior and rarely target tourists. Ubiquitous uses of social media platforms in smartphones have created a tremendous opportunity to gather digital traces of tourists at a large scale. In this paper, we present a framework on how to use location-based data from social media to gather and analyze travel behavior of tourists. We have collected data of about 67,000 users from Twitter using its search interface for Florida. We first propose several filtering steps to create a reliable sample from the collected Twitter data. An ensemble classification technique is proposed to classify tourists and residents from user coordinates. The accuracy of the proposed classifier has been compared against the state-of-the-art classification methods. Finally, different clustering methods have been used to find the spatial patterns of destination choices of tourists. Promising results have been found from the output clusters as they reveal most popular tourist spots as well as some of the emerging tourist attractions in Florida. Performance of the proposed clustering techniques has been assessed using internal clustering validation indices. We have analyzed temporal patterns of tourist and resident activities to validate the classification of the users in two separate groups of tourists and residents. Proposed filtering, identification, and clustering techniques will be significantly useful for building individual-level tourist travel demand models from social media data. 相似文献