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图象编码误差均匀分布压缩方法
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作者 肖自美 曾潮 《中山大学学报(自然科学版)》 CAS CSCD 1989年第4期8-14,共7页
本文利用视觉特性的非相干压缩和图象编码误差均匀分布的观点,将MHT(M-Hada-mard Transform)应用于图象数据压缩,获得了高压缩比和高质量恢复图象。在标量量化情况下,变换域能量分布分散的MHT具有优良变换性能。得出了与传统变换压缩理... 本文利用视觉特性的非相干压缩和图象编码误差均匀分布的观点,将MHT(M-Hada-mard Transform)应用于图象数据压缩,获得了高压缩比和高质量恢复图象。在标量量化情况下,变换域能量分布分散的MHT具有优良变换性能。得出了与传统变换压缩理论和机理不相同的结果。 展开更多
关键词 图象编码 数据压缩 误差均匀分布
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基于迭代最近点的雷达非均匀分布系统误差校正方法
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作者 李鹏飞 孟圣波 雒志顺 《指挥控制与仿真》 2024年第6期37-42,共6页
雷达系统误差配准是雷达组网的前提和基础,对于探测距离远的雷达,其在探测空间内的测量误差呈现明显的非均匀分布特性,导致传统的系统误差校正方法难以满足误差校正需求。针对雷达系统误差存在的非均匀分布特性,将雷达探测空间分成若干... 雷达系统误差配准是雷达组网的前提和基础,对于探测距离远的雷达,其在探测空间内的测量误差呈现明显的非均匀分布特性,导致传统的系统误差校正方法难以满足误差校正需求。针对雷达系统误差存在的非均匀分布特性,将雷达探测空间分成若干小区域,每个小区域可以认为系统误差为定值,此时,可在每个区域内利用迭代最近点算法计算该区域中的雷达系统误差,形成全探测空间内的系统误差补偿矩阵,从而实现对非均匀分布系统误差的准确校正。最后,通过实测数据实验验证了提出方法的有效性。 展开更多
关键词 雷达量测 均匀分布误差 迭代最近点
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DESCRIPTIONS OF THE CYLINDRICAL HELIX WITH NURBS
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作者 孙克豪 乔新 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1997年第2期190-197,共8页
The representation of a cylindrical helix by Non-Uniform Rational B-Spline (NURBS) curves is presented in this paper. A method is proposed to assess the influences produced by different ways to determine the control v... The representation of a cylindrical helix by Non-Uniform Rational B-Spline (NURBS) curves is presented in this paper. A method is proposed to assess the influences produced by different ways to determine the control ver-texes positions of helix. The error distribution cases between the helix approximated by NURBS curves and the original theoretical one are also analyzed. Meanwhile a computational method that guarantees the precision requirements is presented. 展开更多
关键词 helixes CURVES non-uniform rational B-spline (NURBS) error distribution
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Investigation of a Design Modification for Double Helical Gears Reducing Vibration and Noise 被引量:6
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作者 王成 方宗德 贾海涛 《Journal of Marine Science and Application》 2010年第1期81-86,共6页
To reduce vibration and noise and increase transmission efficiency, a three segment method for modifying the pinion profile was proposed. Cutter surface equations were deduced by changing the shape of the cutter-edge,... To reduce vibration and noise and increase transmission efficiency, a three segment method for modifying the pinion profile was proposed. Cutter surface equations were deduced by changing the shape of the cutter-edge, substituting three segment parabolas for the line. The influence of longitudinal tooth modifications on tooth surface load distributions was discussed. Transmission error minimization and uniformity of tooth surface load distribution were chosen as optimization goals and the modified parameters were obtained by applying the complex method. Finally, an experiment comparing the loaded transmission error, vibration, and noise both before and after modifications was carried out. The results indicate that the modified design is reliable. 展开更多
关键词 tooth profile modification tooth longitudinal modification double helical gears loaded transmission error
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