In this paper, we study a band constrained nonnegative matrix factorization （band NMF） problem： for a given nonnegative matrix Y, decompose it as Y ≈ AX with A a nonnegative matrix and X a nonnegative block band m...In this paper, we study a band constrained nonnegative matrix factorization （band NMF） problem： for a given nonnegative matrix Y, decompose it as Y ≈ AX with A a nonnegative matrix and X a nonnegative block band matrix. This factorization model extends a single low rank subspace model to a mixture of several overlapping low rank subspaces, which not only can provide sparse representation, but also can capture signifi- cant grouping structure from a dataset. Based on overlapping subspace clustering and the capture of the level of overlap between neighbouring subspaces, two simple and practical algorithms are presented to solve the band NMF problem. Numerical experiments on both synthetic data and real images data show that band NMF enhances the performance of NMF in data representation and processing.展开更多
Colloidal quantum dots （CQDs）, especially lead chalcogenide CQDs, are regarded as promising materials for the next generation solar cells, due to their large absorption coefficient, excellent charge transport, and m...Colloidal quantum dots （CQDs）, especially lead chalcogenide CQDs, are regarded as promising materials for the next generation solar cells, due to their large absorption coefficient, excellent charge transport, and multiple exciton generation effect. We successfully synthesized highly-crystalline, monodispersed, well-alloyed PbSxTe1-x nanocrystals via a one-pot, hot injection reaction method. Energy-filtered trans- mission electron microscopy suggested that the S and Te anions were uniformly distributed in the alloy nanoparticles. The photovoltaic performance of COD solar cells based on ternary PbSxTe1-x was reported for the first time. The photovoltaic devices using PbSxTe1-x were more efficient than either the pure PbS or the PbTe based devices. In addition, the PbSxTe1-x based devices showed a significantly improved sta- bility than that of the PbTe based devices.展开更多
文摘In this paper, we study a band constrained nonnegative matrix factorization （band NMF） problem： for a given nonnegative matrix Y, decompose it as Y ≈ AX with A a nonnegative matrix and X a nonnegative block band matrix. This factorization model extends a single low rank subspace model to a mixture of several overlapping low rank subspaces, which not only can provide sparse representation, but also can capture signifi- cant grouping structure from a dataset. Based on overlapping subspace clustering and the capture of the level of overlap between neighbouring subspaces, two simple and practical algorithms are presented to solve the band NMF problem. Numerical experiments on both synthetic data and real images data show that band NMF enhances the performance of NMF in data representation and processing.
基金supported by the National High Technology Research and Development Program of China(“863”Program,Grant No.2011AA050520)the Natural Science Foundation of Jiangsu Province(No.BK20130311)+1 种基金the National Natural Science Foundation of China(Grant No.61176054)the Postdoctoral Science Foundation(Grant Nos.2014M550302 and 1302015A),the Collaborative Innovation Center of Suzhou Nano Science and Technology,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Colloidal quantum dots （CQDs）, especially lead chalcogenide CQDs, are regarded as promising materials for the next generation solar cells, due to their large absorption coefficient, excellent charge transport, and multiple exciton generation effect. We successfully synthesized highly-crystalline, monodispersed, well-alloyed PbSxTe1-x nanocrystals via a one-pot, hot injection reaction method. Energy-filtered trans- mission electron microscopy suggested that the S and Te anions were uniformly distributed in the alloy nanoparticles. The photovoltaic performance of COD solar cells based on ternary PbSxTe1-x was reported for the first time. The photovoltaic devices using PbSxTe1-x were more efficient than either the pure PbS or the PbTe based devices. In addition, the PbSxTe1-x based devices showed a significantly improved sta- bility than that of the PbTe based devices.
