A new data structure dynamic watermarking scheme is proposed in this paper. Using Shamir threshold scheme and block encryption, the watermark is divided into several shares. Then these shares are embedded into the dyn...
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A novel watermarking scheme based on chaotic encryption in DWT domain is proposed. The original image is transformed into some sub-band coefficients using discrete wavelet transformation, the logistic chaotic sequence...
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Color image histograms are very useful tools for content based image retrieval (CBIR) that can be applied on features such as colour, texture and shape. As these kinds of histograms results with large variations betwe...
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Disk scheduling algorithms have long been a topic of study in computer science. Many researchers studied the performance of the disk scheduling algorithms. However, perhaps due to the difficulty of implementation, tho...
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Disk scheduling algorithms have long been a topic of study in computer science. Many researchers studied the performance of the disk scheduling algorithms. However, perhaps due to the difficulty of implementation, those early works focused solely on exploring the basic ideas and comparing the performance of these algorithms. No one studied the effect of bad sectors in their performance. In this paper, the performance of the disk scheduling algorithms in the presence of bad sectors is studied. The mapping of bad sectors to spare sectors is considered. We use simulation to do the performance evaluation. Simulation results show that all disk scheduling algorithms are same when there is a high percentage of bad sectors and when the spare sectors are distributed at the end of the disk. It is shown also that with a high percentage of bad sectors, the disk scheduling algorithms perform better if the distribution of spare sectors is at the end of the disk. With a low percentage of bad sectors, the scheduling algorithms perform better if the distribution of spare sectors is within the entire disk. It is shown also that all scheduling algorithms are more sensitive to bad sectors in heavily loaded systems.
The paper analyses the significance of coal mine dispatching drawings digitization,discusses the theory and implement method of WEBGIS,builds the information management system for coal mine dispatching drawings, and d...
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The paper analyses the significance of coal mine dispatching drawings digitization,discusses the theory and implement method of WEBGIS,builds the information management system for coal mine dispatching drawings, and describes the system design and implementation in ***, an application about this system is given.
This Positioning process of the Wireless Sensor Network (WSN) nodes is interfered by multipath, multiple access, especially NLOS transmission effect, Basing on TOA/TDOA positioning technology, the article brings forwa...
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Cipher index is a well established technology for improving query efficiency. However, the existing index schemes have defect of lowness in query hit rate which leads to Internet crowdedness. It is the key for this pr...
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Cipher index is a well established technology for improving query efficiency. However, the existing index schemes have defect of lowness in query hit rate which leads to Internet crowdedness. It is the key for this problem to reduce the redundant tuples in query results. A synthetical cipher index technology to eliminate redundant tuples is presented through considering numeric data and character data respectively. Firstly, according to the query requirement, users' data is concluded into two classifications: the data of various fuzzy querying and that of numeric comparison. Next, cipher indices are established respectively. For the former, a newly cipher index scheme is presented, which determine k character indices for each character composed attribute domain through a mapping function. For the later, an order preserving encryption scheme is used as a cipher index scheme. Meanwhile, the effectiveness and security are analyzed. Finally, the cryptogram query strategy in outsourced databases is presented.
Concurrent access among multiple mobile readers brings about a new problem called reader collision that a readerpsilas transmission is interfered by the others. There have been several works to solve the reader collis...
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Concurrent access among multiple mobile readers brings about a new problem called reader collision that a readerpsilas transmission is interfered by the others. There have been several works to solve the reader collision problem. While they employ time division, frequency division, space division, or centralized scheduling approach, in this paper, we introduce a cooperative, distributed reader collision avoidance algorithm. In particular, it is suitable for energy-efficient wireless mobile network environment cooperated with RFID, since the proposed DiCa (Distributed Tag Access with Collision-Avoidance) is capable of not only avoiding collisions but also changing power state autonomously through only distributed simple interactions between adjacent readers.
Due to advantages in enough number of channels and favorable bandwidth, 2.4 GHz ISM band is used as the most prevalent band for the IEEE802.15.4 LR-WPAN. However, there are an increasing number of other devices and sy...
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Due to advantages in enough number of channels and favorable bandwidth, 2.4 GHz ISM band is used as the most prevalent band for the IEEE802.15.4 LR-WPAN. However, there are an increasing number of other devices and systems which may interfere with the IEEE 802.15.4 communication. Therefore, the coexistence issue is one of the most critical challenges for the IEEE 802.15.4. In this paper, we propose an Adaptive Multi-Channel Utilization scheme (AMCU), to enable a WPAN to coexist with other interfering systems. By utilizing multiple channels dynamically, it is possible that an interfered device or coordinator is recovered quickly, avoiding interference during run time as well as during association stage. In addition, in normal state, each device maintains very low duty cycle as in the standard.
Shape Memory Polymer (SMP) and Shape Memory Alloy (SMA) are known as shape memory materials that mechanical properties change with temperature. Shape-Memory Composite material (SMC) was configured with SMP and SMA. In...
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Shape Memory Polymer (SMP) and Shape Memory Alloy (SMA) are known as shape memory materials that mechanical properties change with temperature. Shape-Memory Composite material (SMC) was configured with SMP and SMA. In this study, SMC is produced for applying the properties of those two materials. The purpose of this study is to get design manuals for SMC controlled by heating or colling. Therefore, the effects of temperature by heating or cooling to SMC were clarified experimentally. We defined elongation coefficient L from tension test and deflection coefficient D from three point bending test to present the mechanical properties of SMC. L and D correspond to Young's modulus of liner elastic body. As a result, the elongation coefficient L of SMP became smaller when temperature exceeded the glass transition zone. On the other hand, L of SMA became larger when temperature exceeded the phase transformation temperature. In addition, Dc of SMC was similar to Dp of a pair of SMP. However, Dc was smaller by 20 to 30 percent than Dp. Also, when temperature exceeded the phase transformation temperature, Dc of SMC became bigger than DP of SMP.
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