为了在有限的时间内产生质量可接受的视频摘要以达到在线使用的要求,提出一种基于视觉特征提取(visual features extraction,VFE)的压缩域视频摘要快速提取方法。从每帧输入视频中提取视觉特征,采用零均值归一化交叉相关(zero mean norm...为了在有限的时间内产生质量可接受的视频摘要以达到在线使用的要求,提出一种基于视觉特征提取(visual features extraction,VFE)的压缩域视频摘要快速提取方法。从每帧输入视频中提取视觉特征,采用零均值归一化交叉相关(zero mean normalized cross correlation,ZNCC)指标检测有相似内容的视频帧组,为每组选择代表性帧,运用2个量化直方图过滤所选择的帧,从而避免视频摘要中可能的冗余或无意义帧。在视频检索国际权威评测(TREC video retrieval evaluation,TRECVID)2007数据集上的实验结果表明,与基于聚类的高斯混合模型、基于熵的模糊C均值聚类和关键帧提取方法相比,该方法提取的视频摘要质量更高,且在时间和空间复杂度上具有明显优势,适合在线实时处理。展开更多
提出一种基于非结构混合网格和有限体积法的有效计算策略,对第二期国际涡流试验项目(second international vortex flow experiment,VFE-2)的尖前缘65°三角翼在马赫数0.4,迎角20.3°,雷诺数2×10~6条件下的亚音速复杂流场...提出一种基于非结构混合网格和有限体积法的有效计算策略,对第二期国际涡流试验项目(second international vortex flow experiment,VFE-2)的尖前缘65°三角翼在马赫数0.4,迎角20.3°,雷诺数2×10~6条件下的亚音速复杂流场结构进行数值模拟,重点探讨了基于计算数据进行该类型复杂涡系干扰表面和空间流场关键特征提取和数据可视化问题.通过与相关试验类比,建立了与先进试验流动显示技术相比拟的定性和定量分析方法,为三角翼这类复杂流场结构的精细分析奠定了技术基础.采用上述方法,细致分析了亚音速三角翼的大迎角复杂旋涡流场结构,得到了与试验一致的结论.研究证实:在大迎角条件下,三角翼流动物理复杂,黏性效应耦合严重,只有通过N-S方程计算才能准确地捕捉主涡和二次涡的发展.展开更多
Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.19）x hydrogen storage alloys were investigated. XRD indicated that La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.1...Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.19）x hydrogen storage alloys were investigated. XRD indicated that La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.19）x alloys consisted of a single phase with CaCus-type structure, and the lattice parameter a and cell volume V increased with increasing x value. The maximum discharge capacity first increased from 319.0 （x=0） to 324.0 mAh/g （x=0.05）, and then decreased to 307.0 mAh/g （x=0.20）. The high-rate dischargeability at the discharge current density of 1200 mA/g first increased from 52.1% （x=0） to 59.1% （x=0.15）, and then decreased to 55.4% （x=0.20）. The hydrogen diffusion in the bulky alloy was responsible for the high-rate dischargeability. Cycling stability first increased with increasing x from 0 to 0.10 and then de- creased when x increased to 0.20, which was resulted fi＇om the synthesized effect of the improvement of the pulverization resistance and the decrease of corrosion resistance.展开更多
文摘为了在有限的时间内产生质量可接受的视频摘要以达到在线使用的要求,提出一种基于视觉特征提取(visual features extraction,VFE)的压缩域视频摘要快速提取方法。从每帧输入视频中提取视觉特征,采用零均值归一化交叉相关(zero mean normalized cross correlation,ZNCC)指标检测有相似内容的视频帧组,为每组选择代表性帧,运用2个量化直方图过滤所选择的帧,从而避免视频摘要中可能的冗余或无意义帧。在视频检索国际权威评测(TREC video retrieval evaluation,TRECVID)2007数据集上的实验结果表明,与基于聚类的高斯混合模型、基于熵的模糊C均值聚类和关键帧提取方法相比,该方法提取的视频摘要质量更高,且在时间和空间复杂度上具有明显优势,适合在线实时处理。
文摘提出一种基于非结构混合网格和有限体积法的有效计算策略,对第二期国际涡流试验项目(second international vortex flow experiment,VFE-2)的尖前缘65°三角翼在马赫数0.4,迎角20.3°,雷诺数2×10~6条件下的亚音速复杂流场结构进行数值模拟,重点探讨了基于计算数据进行该类型复杂涡系干扰表面和空间流场关键特征提取和数据可视化问题.通过与相关试验类比,建立了与先进试验流动显示技术相比拟的定性和定量分析方法,为三角翼这类复杂流场结构的精细分析奠定了技术基础.采用上述方法,细致分析了亚音速三角翼的大迎角复杂旋涡流场结构,得到了与试验一致的结论.研究证实:在大迎角条件下,三角翼流动物理复杂,黏性效应耦合严重,只有通过N-S方程计算才能准确地捕捉主涡和二次涡的发展.
基金Project supported by National Natural Science Foundation of China(51001043)China Postdoctoral Science Special Foundation(201104390,20100470990)+2 种基金Program for Innovative Research Team(in Science and Technology)in the University of Henan Province(2012IRTSTHN007)Baotou Science and Technology Project(2011J1003)the Doctoral Foundation of Henan Polytechnic University(B2010-13)
文摘Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.19）x hydrogen storage alloys were investigated. XRD indicated that La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.19）x alloys consisted of a single phase with CaCus-type structure, and the lattice parameter a and cell volume V increased with increasing x value. The maximum discharge capacity first increased from 319.0 （x=0） to 324.0 mAh/g （x=0.05）, and then decreased to 307.0 mAh/g （x=0.20）. The high-rate dischargeability at the discharge current density of 1200 mA/g first increased from 52.1% （x=0） to 59.1% （x=0.15）, and then decreased to 55.4% （x=0.20）. The hydrogen diffusion in the bulky alloy was responsible for the high-rate dischargeability. Cycling stability first increased with increasing x from 0 to 0.10 and then de- creased when x increased to 0.20, which was resulted fi＇om the synthesized effect of the improvement of the pulverization resistance and the decrease of corrosion resistance.
