排序方式: 共有152条查询结果,搜索用时 15 毫秒
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分析计算在坡道上行驶的全挂牵引车的行驶速度,比较采用不同动力总成及传动系统时车辆性能的变化,总结影响车辆爬坡能力的主要因素,为特殊要求用途的军用车辆配置选用提供参考数据。 相似文献
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作用在直墙上的近破波对建筑物具有极大的破坏力,其作用机理非常复杂,至今尚无统一认识。利用粒子图像测速(PIV)技术与高精度压力传感器对直墙前的近破波流场和破波压力进行了同步测试,通过流场结构与破波压力的同步对比分析,探讨了近破波对直立建筑物的作用机理。 相似文献
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拖带超大型、圆筒状海上石油钻井平台"希望1号"是一项高难度的航海拖带作业,尤其是在航道狭窄的长江江苏段和长江上海段以及长江北支启东入海航道水域,且无前例可鉴.航海者或有关航行评估单位首先必须根据拖航水域的水文、气象条件、通航环境等对拖航进行可行性评估,确定拖带方案,选择合适的拖带方式和建立健全高效的指挥系统,在最佳的时... 相似文献
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为保证海上探测设备与复合电缆的连接具有承载力高、抗冲击的能力,设计海上拖曳复合电缆连接器,介绍其缓冲簧、绞套与球铰头、调节机构的设计方法,海上实际应用表明,该连接器对复合电缆的保护是有效可靠的。 相似文献
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H. S. Kook 《International Journal of Automotive Technology》2008,9(4):493-500
Flows over cavity openings are known to be highly structured and periodic due to the strong sound pressures emitted by the
cavities. This article is concerned with the measurement of flow fields over the sunroof opening of an SUV. Since the PIV
system used in the present work is not capable of taking phase-locked velocity fields during the measurement stage, phase-marked
PIV measurements are performed and the phase-locked velocity fields are retrieved during a post-processing stage. The new
PIV measurement method is shown to yield fairly accurate results with a proper choice of a phase-bandwidth. By using the phase-marked
PIV measurement method, the evolution of large-scale structures in shear flow over the sunroof opening as phase changes is
revealed. The detached shear layer is shown to fluctuate and then form a discrete large vortex convecting and impinging on
the rear roof edge of the SUV. The average convection velocity of the vortex is calculated to be 0.45 of the nominal free
stream flow velocity. Flow fields are compared for four different cases of deflector protrusion and a case without a deflector.
Installation of a deflector can significantly change the flow field. For a deflector that reduces the buffeting noise by more
than 10 dB, it is shown that turbulent fluctuations are initiated by the deflector but do not grow in amplitude as they convect
downstream. As the deflector protrusion is increased, the amount of flow under the deflector increases in general. The flow
exiting from the channel formed by the deflector and an A-frame is shown to increase the thickness of the shear layer near
the leading edge of the sunroof opening. 相似文献
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