10,609 research outputs found

    AutoEncoder Inspired Unsupervised Feature Selection

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    High-dimensional data in many areas such as computer vision and machine learning tasks brings in computational and analytical difficulty. Feature selection which selects a subset from observed features is a widely used approach for improving performance and effectiveness of machine learning models with high-dimensional data. In this paper, we propose a novel AutoEncoder Feature Selector (AEFS) for unsupervised feature selection which combines autoencoder regression and group lasso tasks. Compared to traditional feature selection methods, AEFS can select the most important features by excavating both linear and nonlinear information among features, which is more flexible than the conventional self-representation method for unsupervised feature selection with only linear assumptions. Experimental results on benchmark dataset show that the proposed method is superior to the state-of-the-art method.Comment: accepted by ICASSP 201

    Study of the excited 11^- charm and charm-strange mesons

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    We give a systematical study on the recently reported excited charm and charm-strange mesons with potential 11^- spin-parity, including the Ds1(2700)+D^*_{s1}(2700)^+, Ds1(2860)+D^*_{s1}(2860)^+, D(2600)0D^*(2600)^0, D(2650)0D^*(2650)^0, D1(2680)0D^*_1(2680)^0 and D1(2760)0D^*_1(2760)^0. The main strong decay properties are obtained by the framework of Bethe-Salpeter (BS) methods. Our results reveal that the two 11^- charm-strange mesons can be well described by the further 23 ⁣S12^3\!S_1-13 ⁣D11^3\!D_1 mixing scheme with a mixing angle of 8.73.2+3.98.7^{+3.9}_{-3.2} degrees. The predicted decay ratio B(DK)B(D K)\frac{\mathcal{B}(D^*K)}{\mathcal{B}(D~K)} for Ds1(2860)D^*_{s1}(2860) is 0.620.12+0.220.62^{+0.22}_{-0.12}.~D(2600)0D^*(2600)^0 can also be explained as the 23 ⁣S12^3\!S_1 predominant state with a mixing angle of (7.53.3+4.0)-(7.5^{+4.0}_{-3.3}) degrees. Considering the mass range, D(2650)0D^*(2650)^0 and D1(2680)0D^*_1(2680)^0 are more likely to be the 23 ⁣S12^3\!S_1 predominant states, although the total widths under both the 23 ⁣S12^3\!S_1 and 13 ⁣D11^3\!D_1 assignments have no great conflict with the current experimental data. The calculated width for LHCb D1(2760)0D^*_1(2760)^0 seems about 100 \si{MeV} larger than experimental measurement if taking it as 13 ⁣D11^3\!D_1 or 13 ⁣D11^3\!D_1 dominant state cuˉc\bar u. The comparisons with other calculations and several important decay ratios are also present. For the identification of these 11^- charm mesons, further experimental information, such as B(Dπ)B(Dπ)\frac{\mathcal{B}(D\pi)}{\mathcal{B}(D^*\pi)} are necessary.Comment: 18 pages, 3 figure

    Transport of the Saharan dust air plumes over the tropical North Atlantic from FORMOSAT–3/COSMIC observation

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    AbstractLong–range transport of the Saharan dust plumes during May–August of each year is a prominent feature over the tropical North Atlantic. Observations of temperature profiles are highly desirable in clarifying the impacts of the Saharan dust plumes over the tropical North Atlantic. In this work we evaluate positive temperature anomalies (inversions in the lower troposphere) in the North Atlantic low troposphere originating from Western Africa, and to examine the correspondence of these events to Saharan dust plumes, using several temperature sources and satellite–detected measurements of Aerosol Index. We combine profiles of temperature observations from FORMOSAT–3/COSMIC (F3C) with aerosol observations from Ozone Monitoring Instrument (OMI) to provide direct evidence of the Saharan dust plumes modifying environmental stability. The F3C observations show good profile measurements compared with the radiosondes in the lower troposphere, with the average temperature differences less than 0.5K. The F3C results were also compared with the Aqua Advanced Infrared Radiation Sounder (AIRS) and meteorological analyses from the National Centers for Environmental Predictions (NCEP), the United Kingdom Met Office (UKMO), and the European Centre for Medium Range Weather Forecast (ECMWF). Our results show that hot air plumes are associated with the Saharan dust plumes during their transport across the tropical North Atlantic. There were eleven distinctive hot air plumes during May–August 2007 and 2008, respectively. These hot air plumes increase environmental temperatures below 5–km altitudes, with the maximum increase of 1–2K around 2–km. This leads to increase of environmental stability below 2–km altitudes and decrease of environmental stability between 2– and 5–km altitudes. By changing the vertical distribution of environmental stability, the Saharan dust plumes act to stabilize environmental air below 2–km while destabilize environmental air from 2– to 5–km altitudes. These results are distinctively presented in the F3C and AIRS observations but less obvious in the meteorological analyses
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