由于航空发动机工作环境复杂,故障数据稀缺,且单一传感器难以全面表征中介轴承状态,导致现有诊断方法准确率较低。为此,提出了一种基于多传感器信息融合(multi-sensor information fusion,MSIF)和二维卷积神经网络(2-dimensional convol...由于航空发动机工作环境复杂,故障数据稀缺,且单一传感器难以全面表征中介轴承状态,导致现有诊断方法准确率较低。为此,提出了一种基于多传感器信息融合(multi-sensor information fusion,MSIF)和二维卷积神经网络(2-dimensional convolutional neural network,2DCNN)的航空发动机中介轴承故障诊断方法。该方法将多个传感器的时域和频域特征融合为一张RGB图像,从而更加全面地表征中介轴承状态。然后,将生成的RGB图像输入2DCNN模型完成故障诊断。在真实航空发动机试验台的轴承故障数据上的测试中,当训练集与测试集比例为1∶9的小样本条件时,部分传感器组合的诊断准确率即可达99%;比例为7∶3时所有传感器组合的准确率均达100%。此外,所提方法的诊断准确率与基础研究相比,至少提高了13%;且超越了进行对比的5种先进方法。结果表明,该方法不仅实现了航空发动机中介轴承故障的快速精准识别,还在小样本条件下展现出了卓越的诊断性能。展开更多
Snow on sea ice is a sensitive indicator of climate change because it plays an important role regulating surface and near surface air temperatures. Given its high albedo and low thermal conductivity, snow cover is con...Snow on sea ice is a sensitive indicator of climate change because it plays an important role regulating surface and near surface air temperatures. Given its high albedo and low thermal conductivity, snow cover is considered a key reason for amplified warming in polar regions. This study focuses on retrieving snow depth on sea ice from brightness temperatures recorded by the Microwave Radiation Imager(MWRI) on board the FengYun(FY)-3 B satellite. After cross calibration with the Advanced Microwave Scanning Radiometer-EOS(AMSR-E) Level 2 A data from January 1 to May 31, 2011, MWRI brightness temperatures were used to calculate sea ice concentrations based on the Arctic Radiation and Turbulence Interaction Study Sea Ice(ASI) algorithm. Snow depths were derived according to the proportional relationship between snow depth and surface scattering at 18.7 and 36.5 GHz. To eliminate the influence of uncertainties in snow grain sizes and sporadic weather effects, seven-day averaged snow depths were calculated. These results were compared with snow depths from two external data sets, the IceBridge ICDIS4 and AMSR-E Level 3 Sea Ice products. The bias and standard deviation of the differences between the MWRI snow depth and IceBridge data were respectively 1.6 and 3.2 cm for a total of 52 comparisons. Differences between MWRI snow depths and AMSR-E Level 3 products showed biases ranging between-1.01 and-0.58 cm, standard deviations from 3.63 to 4.23 cm, and correlation coefficients from 0.61 to 0.79 for the different months.展开更多
基金Funding for this project was provided by the National Key Research and Development Program of China (No. 2016YFC1402704)the Global Change Research Program of China (No. 2015CB953901)
文摘Snow on sea ice is a sensitive indicator of climate change because it plays an important role regulating surface and near surface air temperatures. Given its high albedo and low thermal conductivity, snow cover is considered a key reason for amplified warming in polar regions. This study focuses on retrieving snow depth on sea ice from brightness temperatures recorded by the Microwave Radiation Imager(MWRI) on board the FengYun(FY)-3 B satellite. After cross calibration with the Advanced Microwave Scanning Radiometer-EOS(AMSR-E) Level 2 A data from January 1 to May 31, 2011, MWRI brightness temperatures were used to calculate sea ice concentrations based on the Arctic Radiation and Turbulence Interaction Study Sea Ice(ASI) algorithm. Snow depths were derived according to the proportional relationship between snow depth and surface scattering at 18.7 and 36.5 GHz. To eliminate the influence of uncertainties in snow grain sizes and sporadic weather effects, seven-day averaged snow depths were calculated. These results were compared with snow depths from two external data sets, the IceBridge ICDIS4 and AMSR-E Level 3 Sea Ice products. The bias and standard deviation of the differences between the MWRI snow depth and IceBridge data were respectively 1.6 and 3.2 cm for a total of 52 comparisons. Differences between MWRI snow depths and AMSR-E Level 3 products showed biases ranging between-1.01 and-0.58 cm, standard deviations from 3.63 to 4.23 cm, and correlation coefficients from 0.61 to 0.79 for the different months.
基金国家自然科学基金(the National Natural Science Foundation of China under Grant No.60672137)教育部博士点基金项目(SpecializedResearch Fund for the Doctoral Program of Higher Education of China under Grant No.20060497015)
