查看更多>>摘要：Traditional photography focuses on the optimization of lenses for a perfect imaging system. However, with the great developments of computational resources and optical modulation devices, we can achieve more powerful imaging abilities with concise optics. Computational photography is such an emerging inter-disciplinary field by incorporating computational strategy in traditional imaging system to break the limitations in various dimensions such as spectrum, time and space. Recent advances in different aspects have aroused great interests and introduced tremendous applications in biology, material science and computer vision.
查看更多>>摘要：Discernibility matrix is a beautiful theoretical result to get reducts in the rough set, but the existing algorithms based on discernibility matrix share the same problem of heavy computing load and large store space, since there are numerous redundancy elements in discernibility matrix and these algorithms employ all elements to find reducts. We introduce a new method to compute attribute significance. A novel approach is proposed, called minimal element selection tree, which utilizes many strategies to eliminate redundancy elements in discernibility matrix. This paper presents two methods to find out a minimal reduct for a given decision table based this tree structure. The experimental results with UCI data show that the proposed approaches are effective and efficient than the benchmark methods.
查看更多>>摘要：Obtaining the classification of urban functions is an integral part of urban planning. Currently, public bicycle systems are booming in these years. It conveys human mobility and activity information, which can be closely related to the social function of an urban region. This paper discusses the potential use of public bicycle systems for recognizing the social function of urban regions by using one year's rent/return data of public bicycles. We found that rent/return dynamics, extracted from public bicycle systems, exhibited clear patterns corresponding to the urban function classes of these regions. With seven features designed to characterize the rent/return pattern, our method based on Smooth support vector machine (SSVM) is proposed to recognize social function classes of urban regions. We evaluate our method based on the large-scale real-world dataset collected from the public bicycle system of Hangzhou. The results show that our method can efficiently recognize different types of urban function areas. Classification results using the proposed SSVM achieved the best classification accuracy of 96.15％.
查看更多>>摘要：With the rapid development of network information technology and the wide application of smart phones, tablet PCs and other mobile terminals, online education plays an increasingly important role in social life. This article focuses on mining useful data from the massive online education data, by using transfer learning, relying on Hadoop, to construct Online education data classification framework (OEDCF), and design an algorithm Tr_MAdaBoost. This algorithm overcomes the traditional classification algorithms in which the required data must be restricted to independent and identically distributed data, since online education using this new algorithm can achieve the correct classification even it has different data distribution. At the same time, with the help of Hadoop's parallel processing architecture, OEDCF can greatly enhance the efficiency of data processing, create favorable conditions for learning analysis, and promote personalized learning and other activities of big data era.
查看更多>>摘要：With the rapid development of the smart driving technology, the security of smart driving algo-rithms is becoming more and more important. Four core smart driving algorithms are determined by studying the architecture of smart driving algorithm. These algorithms comprise local path planning, pedestrian detection, lane detection and obstacle detection. The security issues of these algorithms are investigated by closely examining the work carried out by the algorithms. We found that there are vulnerabilities in all four algorithms. These vulnerabilities can cause abnormality and even road accidents for the smart cars. The final experiment shows that the vulnerabilities of these algorithms do exist under certain circumstances and therefore have high security risks. This study will lay a foundation to improve the security of the smart driving system.
查看更多>>摘要：New formulae for point addition and point doubling on elliptic curves over prime fields are presented. Based on these formulae, an improved Montgomery algorithm is proposed. The theoretical analysis indicates that it is about 13.4％ faster than Brier and Joye's Montgomery algorithm. Experiments on the elliptic curve over a 256-bit prime field recommended by the National Institute of Standards and Technology and over a 256-bit prime field in Chinese elliptic curve standard SM2 support the theoretical analysis.
查看更多>>摘要：Rotation symmetric Boolean functions (RSBFs) have attracted widespread attention due to their good cryptographic properties. We present a new construction of RSBFs with optimal algebraic immunity on odd number of variables. The nonlinearity of the new function is much higher than other best known RSBFs with optimal algebraic immunity. The algebraic degree of the constructed n-variable RSBF can achieve the upper bound n?1 when n/2 is odd or when n/2 is a power of 2 for n≥11. In addition, the constructed function can possess almost perfect immunity to fast algebraic attacks for n=11, 13, 15.
查看更多>>摘要：Binding access policies to data, Ciphertext-policy attribute-based encryption (CP-ABE) enables data access control to be independent from a certain application and lets users face data directly. It is regarded as one of the most suitable access control methods in cloud storage system and gets the attention of extensive researches. In those researches, Hierarchical cryptography architecture (HCA) is often applied to improve the efficiency of the system. There exist two open issues: illegal leakage of symmetric keys and low efficiency of revocation of an attribute of a user. We propose an Access control scheme under Hierarchical cryptography architecture (ACS-HCA). In this scheme, key derivation mechanism and forward derivation function are used to avoid the leakage of symmetric keys, All-or-Nothing transform is used to prevent the illegal reuse of symmetric keys, and attribute revocation is realized without re-issuing other users' private keys. Analyses and simulations demonstrate that our scheme sustains less encrypting cost on each owner and less decrypting cost on each user, but gain high efficiency in revocation of an attribute of a user.
查看更多>>摘要：The fair division theory has emerged as a promising approach for the throughput allocation of hybrid storage system. While most of them cause the unfair allocation of the throughput servicing time due to taking no consideration of clients' request IO latencies. We propose one Servicing time allocation method based on the client grouping mechanism(STCG), STCG establishes fair allocation policies based on clients' workload weights, which can achieve a fair throughput servicing time allocation, and can maximize the resource utilization. The experimental result shows that STCG's allocation enjoys fair properties in each client group, and compared with the method proposd recently, STCG can improve the resource utilization about 12％–330％.
查看更多>>摘要：Accurate segmentation of Optic disc (OD) is significant for the automation of retinal analysis and retinal diseases screening. This paper proposes a novel optic disc segmentation method based on the saliency. It includes two stages: optic disc location and saliency-based segmentation. In the location stage, the OD is detected using a matched template and the density of the vessels. In the segmentation stage, we treat the OD as the salient object and formulate it as a saliency detection problem. To measure the saliency of a region, the boundary prior and the connectivity prior are exploited. Geodesic distance to the window boundary is computed to measure the cost the region spends to reach the window boundary. After a threshold and ellipse fitting, we obtain the OD. Experimental results on two public databases for OD segmentation show that the proposed method achieves the-state-of-the-art performance.
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