Overview of the Mars climate station for Tianwen-1 mission

The background and scientific objectives of the Mars Climate Station(MCS)for Tianwen-1 are introduced,accompanied by a comparative review of the status of related meteorological observation missions and of advanced sensing technologies.As one of the China Tianwen-1 Mission’s principal scientific payloads,the MCS contains four measurement sensors and one electronic processing unit that are specially designed to measure local temperature,pressure,wind,and sound on the Martian surface.The MCS’s measurement principles,technical schemes,ground calibration techniques,and adaptability evaluation to the Mars surface environment of MCS are introduced in details.The conclusion presents measurement performance specifications of the MCS,based on ground test results,that will provide guidance to future research based on data from the Tianwen-1 and later Mars missions.

三分量光纤地震计

提出并实验论证了一种全金属三分量光纤地震计。基于机电理论给出了理论分析。标定结果表明:在5~400Hz频带,轴向灵敏度约41dB(0dB=1rad/g),波动±2dB。横向灵敏度约-40dB。地震计中的3个加速度计的加速度灵敏度波动在±2.5dB之内。相位产生载波的最小相位解调检测准度为10^(-5)rad/Hz^(1/2),最小可检测加速度值经计算可达到90ng/Hz^(1/2)。

一种基于χ~2统计的特征分类选择方法研究

【目的】针对传统χ~2统计无法保证各类别之间信息的均衡性从而影响分类效果的问题,改进χ~2统计以提高其应用效果。【方法】通过分析传统χ~2统计的特征选择过程及其局限,提出一种基于χ~2统计的特征分类选择方法,根据特征词与每一类的关联度分类别选取特征词。【结果】以SVM为分类模型,通过实验对比改进前后的方法对文本分类效果的影响,结果表明基于χ~2统计的特征分类选择方法在准确率、平均分类准确率、最低分类准确率、稳定性和系统运行时间等方面得到显著改善。【局限】特征词选取数量较少时,改进前后差异不明显。【结论】基于χ~2统计的特征分类选择方法,有效改善了分类模型的稳定性与泛化性能,使分类准确率的波动幅度减小,分类过程的效率显著提高。