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MULTIDIMENSIONAL BSDES WITH UNIFORMLY CONTINUOUS GENERATORS AND GENERAL TIME INTERVALS
Shengjun Fan,Yanbin Wang,Lishun Xiao 대한수학회 2015 대한수학회보 Vol.52 No.2
This paper is devoted to solving a multidimensional backward stochastic differential equation with a general time interval, where the generator is uniformly continuous in (y, z) non-uniformly with respect to t. By establishing some results on deterministic backward differential equations with general time intervals, and by virtue of Girsanov’s theorem and convolution technique, we prove a new existence and uniqueness result for solutions of this kind of backward stochastic differential equations, which extends the results of [8] and [6] to the general time interval case.
MULTIDIMENSIONAL BSDES WITH UNIFORMLY CONTINUOUS GENERATORS AND GENERAL TIME INTERVALS
Fan, Shengjun,Wang, Yanbin,Xiao, Lishun Korean Mathematical Society 2015 대한수학회보 Vol.52 No.2
This paper is devoted to solving a multidimensional backward stochastic differential equation with a general time interval, where the generator is uniformly continuous in (y, z) non-uniformly with respect to t. By establishing some results on deterministic backward differential equations with general time intervals, and by virtue of Girsanov's theorem and convolution technique, we prove a new existence and uniqueness result for solutions of this kind of backward stochastic differential equations, which extends the results of [8] and [6] to the general time interval case.
Robust Image Hashing for Tamper Detection Using Non-Negative Matrix Factorization
Tang, Zhenjun,Wang, Shuozhong,Zhang, Xinpeng,Wei, Weimin,Su, Shengjun The Institute of Electronics and Information Engin 2008 JUCT : Journal of Ubiquitous Convergence Technolog Vol.2 No.1
The invariance relation existing in the non-negative matrix factorization (NMF) is used for constructing robust image hashes in this work. The image is first re-scaled to a fixed size. Low-pass filtering is performed on the luminance component of the re-sized image to produce a normalized matrix. Entries in the normalized matrix are pseudo-randomly re-arranged under the control of a secret key to generate a secondary image. Non-negative matrix factorization is then performed on the secondary image. As the relation between most pairs of adjacent entries in the NMF's coefficient matrix is basically invariant to ordinary image processing, a coarse quantization scheme is devised to compress the extracted features contained in the coefficient matrix. The obtained binary elements are used to form the image hash after being scrambled based on another key. Similarity between hashes is measured by the Hamming distance. Experimental results show that the proposed scheme is robust against perceptually acceptable modifications to the image such as Gaussian filtering, moderate noise contamination, JPEG compression, re-scaling, and watermark embedding. Hashes of different images have very low collision probability. Tampering to local image areas can be detected by comparing the Hamming distance with a predetermined threshold, indicating the usefulness of the technique in digital forensics.
Fang Zheng,Shengjun Shao,Jiao Wang,Shuai Shao 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.8
Loess is mostly distributed in an unsaturated state in nature, and the complexity of the engineering properties of unsaturated soil is mainly due to the existence of matric suction. Therefore, matric suction must be considered in investigating the mechanical properties of unsaturated loess. However, soils are most often subjected to three principal stresses with different magnitudes in practical engineering. For the sake of examining and discussing the mechanical behaviour of unsaturated natural loess under a complex stress path, a suction-controlled true triaxial apparatus with a rigid-flexible boundary is used to test unsaturated natural loess under a complicated stress path. Four trials of isotropic consolidation tests are conducted on natural loess under suction-controlled conditions via the true triaxial apparatus. The consolidation yield characteristics of the natural loess under different matric suctions are investigated. Forty-eight trials of consolidated drained true triaxial tests under suction-controlled conditions are conducted on unsaturated natural loess to examine and discuss the influence of the matric suction and intermediate principal stress parameter (b-value). The consolidated drained trials are performed under a constant net mean stress and a constant matric suction with different intermediate principal stress parameters (b-values). Stress-strain curves and failure envelopes of the natural loess are also presented. The results indicate that the stress-strain-strength response of unsaturated natural loess depends on the matric suction and intermediate principal stress parameter under true triaxial conditions.
Robust Image Hashing for Tamper Detection Using Non-Negative Matrix Factorization
Zhenjun Tang,Shuozhong Wang,Xinpeng Zhang,Weimin Wei,Shengjun Su 대한전자공학회 2008 JUCT : Journal of Ubiquitous Convergence Technolog Vol.2 No.1
The invariance relation existing in the non-negative matrix factorization (NMF) is used for constructing robust image hashes in this work. The image is first re-scaled to a fixed size. Low-pass filtering is performed on the luminance component of the re-sized image to produce a normalized matrix. Entries in the normalized matrix are pseudo-randomly re-arranged under the control of a secret key to generate a secondary image. Non-negative matrix factorization is then performed on the secondary image. As the relation between most pairs of adjacent entries in the NMF's coefficient matrix is basically invariant to ordinary image processing, a coarse quantization scheme is devised to compress the extracted features contained in the coefficient matrix. The obtained binary elements are used to form the image hash after being scrambled based on another key. Similarity between hashes is measured by the Hamming distance. Experimental results show that the proposed scheme is robust against perceptually acceptable modifications to the image such as Gaussian filtering, moderate noise contamination, JPEG compression, re-scaling, and watermark embedding. Hashes of different images have very low collision probability. Tampering to local image areas can be detected by comparing the Hamming distance with a predetermined threshold, indicating the usefulness of the technique in digital forensics.
Bacterial bug-out bags: outer membrane vesicles and their proteins and functions
Kesavan Dineshkumar,Vasudevan Aparna,Liang Wu,Jie Wan,Mohamod Hamed Abdelaziz,Zhaoliang Su,Shengjun Wang,Huaxi Xu 한국미생물학회 2020 The journal of microbiology Vol.58 No.7
Among the major bacterial secretions, outer membrane vesicles (OMVs) are significant and highly functional. The proteins and other biomolecules identified within OMVs provide new insights into the possible functions of OMVs in bacteria. OMVs are rich in proteins, nucleic acids, toxins and virulence factors that play a critical role in bacteria-host interactions. In this review, we discuss some proteins with multifunctional features from bacterial OMVs and their role involving the mechanisms of bacterial survival and defence. Proteins with moonlighting activities in OMVs are discussed based on their functions in bacteria. OMVs harbour many other proteins that are important, such as proteins involved in virulence, defence, and competition. Overall, OMVs are a power-packed aid for bacteria, harbouring many defensive and moonlighting proteins and acting as a survival kit in case of an emergency or as a defence weapon. In summary, OMVs can be defined as bug-out bags for bacterial defence and, therefore, survival.