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在磁悬挂天平偏航控制中,偏航线圈中的电流变化对模型姿态变化影响十分显著.为了提高天平的偏航控制精度,有必要对天平偏航电磁场进行更为精确的分析.该文采用有限单元法对磁悬挂天平偏航电磁场进行了分析,得到了比传统计算方法更为准确的结果,并在实验中进行了验证,从而为磁悬挂天平的偏航控制提供了参考. 相似文献
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用平面自治系统的极限环理论和分支理论研究了一类具有普遍意义的非线性系统,讨论了该系统极限环的存在性和唯一性,同时解决了系统极限环的个数和分布问题。应用所得结论,推广并改进了前人的结果。 相似文献
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战争就是交战双方作战体系之间的对抗.体系贡献率评估是体系建设和分析重点关注的问题,是对作战要素在作战体系中所发挥作用的一种度量.针对体系的复杂系统特性,构建SDAE+Softmax模型对体系效能涌现过程进行建模,模型描述了体系基础指标与任务指标之间的关系.提取Softmax分类器的分类概率相对值作为体系贡献率评估的综合特征指标,量化体系组分改变对体系效能的影响.基于SDAE+Softmax模型的评估方法,为体系贡献率评估提供了全新的思路,是对传统评估方法的突破. 相似文献
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In this study, 40CrMnSiB steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A mid-explosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40CrMnSiB steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thick-ness and the number of the circumferential divisions. The results show that as the tempering temper-ature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface. 相似文献
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时域有限差分法 (FDTD)在电磁场数值计算中占有重要的地位。本文发现并证明FDTD是时域多分辨分析 (MRTD)的特例。利用小波 -伽略金方法求解麦克斯韦方程过程中 ,基函数为一般的小波分析中的尺度函数或小波函数 ,可以得到MRTD算法。如果基函数选为Haar小波尺度函数 ,可以推得FDTD算法。如果基函数选为Haar小波包中的尺度函数 ,可以得到高阶FDTD算法。通过算例比较 ,MRTD比FDTD的计算效率更高 相似文献
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从多分辨分析思想出发 ,推导出一种计算数值积分的算法 ,通过加强迫函数改善其精度。利用张量扩张的原理 ,将其推广到计算多维数值积分。结果表明 ,它不但与传统的Simpson算法有较好的一致性 ,而且对于震荡积分也有较高的精度。 相似文献
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“财会会计学”课程在会计学专业方面起着承上启下的重要作用。本文分析了石河子大学“财务会计学”课程的优势 ,回顾和总结了石河子大学“财务会计学”课程建设的主要做法、取得的成效及存在的问题和不足 ,并对石河子大学的“财务会计学”课程建设提出了几点体会与思考。 相似文献
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