A grid technology together with data warehouse and mediator is used to develop the railway transport management information system （TMIS）, which is aiming at managing and publishing all kinds of enterprise resources...A grid technology together with data warehouse and mediator is used to develop the railway transport management information system （TMIS）, which is aiming at managing and publishing all kinds of enterprise resources among dynamic collections of such information systems with heterogeneous architectures and distributed in geography within Chinese Ministry of Railway. As one logical information integration framework and a uniform interface for accessing resources, a prototype named railway information grid （RIG） is proposed. Its main modules and the key technologies, together with its feasibility, are discussed in detail. RIG can not only provide the integral information service and the interoperability of information at the application level, but also bring us such benefits as： easy use, high efficiency, and reasonable total cost of ownership.展开更多
A content authentication technique based on JPEG-to-JPEG watermarking is proposed in this paper. In this technique, each 8x8 block in a JPEG compressed image is first processed by entropy decoding, and then the quanti...A content authentication technique based on JPEG-to-JPEG watermarking is proposed in this paper. In this technique, each 8x8 block in a JPEG compressed image is first processed by entropy decoding, and then the quantized discrete cosine transform （DCT） is applied to generate DCT coefficients： one DC coefficient and 63 AC coefficients in frequency coefficients. The DCT AC coefficients are used to form zero planes in which the watermark is embedded by a chaotic map. In this way, the watermark information is embedded into JPEG compressed domain, and the output watermarked image is still a JPEG format. The proposed method is especially applicable to content authentication of JPEG image since the quantized coefficients are modified for embedding the watermark and the chaotic system possesses an important property with the high sensitivity on initial values. Experimental results show that the tamper regions are localized accurately when the watermarked JPEG image is maliciously tampered.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.60702025
文摘A grid technology together with data warehouse and mediator is used to develop the railway transport management information system （TMIS）, which is aiming at managing and publishing all kinds of enterprise resources among dynamic collections of such information systems with heterogeneous architectures and distributed in geography within Chinese Ministry of Railway. As one logical information integration framework and a uniform interface for accessing resources, a prototype named railway information grid （RIG） is proposed. Its main modules and the key technologies, together with its feasibility, are discussed in detail. RIG can not only provide the integral information service and the interoperability of information at the application level, but also bring us such benefits as： easy use, high efficiency, and reasonable total cost of ownership.
基金supported by the National Natural Science Foundation of China under Grant No.60702025the Research Fund for the Doctoral Program of Higher Education under Grant No.20070613024Sichuan Youth Science & Technology Foundation under Grant No.07ZQ026-004
文摘A content authentication technique based on JPEG-to-JPEG watermarking is proposed in this paper. In this technique, each 8x8 block in a JPEG compressed image is first processed by entropy decoding, and then the quantized discrete cosine transform （DCT） is applied to generate DCT coefficients： one DC coefficient and 63 AC coefficients in frequency coefficients. The DCT AC coefficients are used to form zero planes in which the watermark is embedded by a chaotic map. In this way, the watermark information is embedded into JPEG compressed domain, and the output watermarked image is still a JPEG format. The proposed method is especially applicable to content authentication of JPEG image since the quantized coefficients are modified for embedding the watermark and the chaotic system possesses an important property with the high sensitivity on initial values. Experimental results show that the tamper regions are localized accurately when the watermarked JPEG image is maliciously tampered.
