A Non-Destructive Distinctive Method for Discrimination of Automobile Lubricant Variety by Visible and Short-Wave Infrared Spectroscopy

A novel method which is a combination of wavelet packet transform (WPT), uninformative variable elimination by partial least squares (UVE-PLS) and simulated annealing (SA) to extract best variance information among different varieties of lubricants is presented. A total of 180 samples (60 for each variety) were characterized on the basis of visible and short-wave infrared spectroscopy (VIS-SWNIR), and 90 samples (30 for each variety) were randomly selected for the calibration set, whereas, the remaining 90 samples (30 for each variety) were used for the validation set. The spectral data was split into different frequency bands by WPT, and different frequency bands were obtained. SA was employed to look for the best variance band (BVB) among different varieties of lubricants. In order to improve prediction precision further, BVB was processed by UVE-PLS and the optimal cutoff threshold of UVE was found by SA. Finally, five variables were mined, and were set as inputs for a least square-support vector machine (LS-SVM) to build the recognition model. An optimal model with a correlation coefficient (R) of 0.9850 and root mean square error of prediction (RMSEP) of 0.0827 was obtained. The overall results indicated that the method of combining WPT, UVE-PLS and SA was a powerful way to select diagnostic information for discrimination among different varieties of lubricating oil, furthermore, a more parsimonious and efficient LS-SVM model could be obtained

最大クリーク問題を用いた複数等質テスト自動構成手法とその近似手法

本研究ではe テスティングにおける複数等質テスト自動構成手法を提案・開発した. 複数等質テストとは, それぞれのテストに含まれるテスト項目は異なるが, 統計的な性質(例えば, 得点分布や項目反応理論に基づく情報量等) が等しいテスト群である. 本手法の特徴は, 複数等質テスト構成を最大クリーク問題として解くことで, 与えられたアイテムバンク・テスト構成条件で最大数のテストを構成可能な点である. これにより従来手法より多くのテストを構成可能であり,よりアイテムバンクを有効活用可能である. しかし, 本手法の厳密な計算はコストが高く, 大規模なテスト構成では計算が困難である. そのために，さらに， 限られた計算量でテスト構成を行う乱数探索を用いた近似手法を提案した. これにより, 厳密法の指数時間計算量と多項式空間計算量を定数オーダーへと軽減できた. 最後に提案手法の有効性を示すため, シミュレーション及び実データを用いた実験を行い, 他手法より多くのテストを構成できることを示した.電気通信大学201