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本文首次使用了曲六面体带节点导数等参元,通过变分法,计算了三维机翼亚临界定常位势流中的压力分布,计算结果与试验结果符合较好,文中还例用了有限元法中的局部线性化理论,插值出元素中心点密度去处理迭代过程中元素系数阵的计算,其结果与通常的有限元计算相吻合,但计算时间却明显减少了。文章最后以有限元法的局部线性化理论和局部线性化的有限元法做了阐述。 相似文献
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We investigate the dynamics of pedestrian counter flow by using a multi-grid topological pedestrian counter flow model.In the model,each pedestrian occupies multi-rather than only one grid,and interacts with others in the form of topological interaction,which means that a moving pedestrian interacts with a fixed number of those nearest neighbours coming from the opposite direction to determine his/her own moving direction.Thus the discretization of space and time are much finer,the decision making process of the pedestrian is more reliable,which all together makes the moving behaviour and boundary conditions much more realistic.When compared with field observations,it can be found that the modified model is able to reproduce well fitted pedestrian collective behaviour such as dynamical variation of lane formation,clustering of pedestrians in the same direction,etc.The fundamental diagram produced by the model fits also well with field data in the free flow region.Further analyses indicate that with the increase of the size of pedestrian counter flow system,it becomes harder for the system to transit into a jamming state,while the increase of interaction range does not change the transition point from free flow to jamming flow in the multi-grid topological counter flow model.It is also found that the asymmetry of the injection rate of pedestrians on the boundaries has direct influence on the process of transition from free flow to jamming flow,i.e.,a symmetric injection makes it easier for the system to transit into jamming flow. 相似文献
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氧化锆增韧陶瓷与A95陶瓷抗侵彻性能对比实验研究 总被引:4,自引:1,他引:4
使用穿甲弹对两种陶瓷材料,10%氧化锆增韧陶瓷和A95陶瓷,开展了系列弹道实验研究。分析了各自的抗弹防护系数随射弹入射速度的变化规律,并分析了材料强度和韧性对其抗侵彻性能的影响。实验表明:两种陶瓷材料的质量防护系数都明显高于1,但在射弹入射速度为1000.0~1300m/s的范围内,A95陶瓷靶的抗侵彻能力高于增韧陶瓷的抗侵占能力。随着入射速度的提高,增韧陶瓷的抗侵彻能力提高的更快,并在某点出现转折入射速度以上,大约1300m/s,其与A95陶瓷的抗侵彻能力趋于相同,显示了增韧陶瓷在抗高速侵彻方面的适用性。 相似文献
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采用经典的火羽流模型,预测了2008奥运国家主体育场典型火灾场景下火源上方不同高度处
的烟气温度;结合钢结构在不同温度条件下的强度、弹性模量参数,选取了保守的钢结构极
限环境温度值;综合上述两个方面的结果,确定了2008奥运国家主体育场钢结构中需要开展
消防保护的区域为:观众席座椅区距离座椅的垂直距离小于10.2 m的区域. 相似文献
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基于互相关的DPIV图像诊断方法研究 总被引:12,自引:1,他引:12
数字粒子图像测速技术( D P I V— Digtal Particle Im aging Velocim etry)已在国内外得到广泛的重视和应用,但目前能否推广应用的关键在于能否发展一种快速的诊断方法,本文介绍一种基于互相关算法的快速诊断方法的原理,编程并应用于水箱中的水受到低速射流的影响而产生卷吸的实验。 相似文献