Applied Mechanics and Materials Vols. 543-547

Abstract: The P2P technology consumes the largest proportion of network traffic and is usually encrypted, which is lack of supervision. Accurate and rapid identification of encrypted P2P traffic, represented by the famous Skype, is of great significance to improve the network quality of service and enhance security control. In this paper, a trends-aware protocol fingerprints model is proposed based on the statistical signatures of signaling interactions and content transfer phase of Skype. The proposed method can sense traffic trends by trends-aware weighting functions and identify Skype traffic with anomaly scores in real-time. Experimental results show that the precision and real-time performances of the proposed algorithm is better than several state-of-art encrypted traffic identification methods, such as the protocol fingerprints and C4.5 algorithm.

Abstract: This document analyzes the security drawback of the Hash-based algorithm authentication protocols which is frequently used in low-cost RFID systems, and proposes a lightweight mutual authentication protocol. In the proposed protocol, all authenticated information is encrypted , the location privacy is also provided by refreshing an identifier of a tag in each session and lost massages can be recovered from many attacks such as spoofing attacks. The comparison result of the simulation experiment and the formal correctness proof of the proposed authentication protocol is based on BAN logic. It shows that the proposed protocol in this article greatly enhance the capability of verifiability, confidentiality and integrality, it also corrects the existing Hash-based protocol secure deficiency so that it is more suitable for low-cost RFID systems than those existing ones.

Abstract: In this paper, we proposed a more practical spectrum sensing order problem in cognitive radio networks (CRN), considering the effect of different traffic of second user (SU). We discard the impractical assumption that SU has data packets to transmit all the time, and use the actually packets per second rather than the channel capacity as the definition of throughput, to reformulate the optimal sensing order problem. The new method to decide sensing order can improve the throughput performance in practical system.

Abstract: Based on the theoretical analysis of both the characteristics for the concatenation code and the two concatenation code-types in ITU-T G.975.1, a new RS(255,223) + BCH(2040,1930) concatenation code for optical communications is constructed and analyzed. The simulation results show that this new concatenation code, compared with the RS(255,239)+CSOC(k0/n0=6/7,J=8) code in ITU-T G.975.1, had a lower redundancy and the better error-correction performance. Furthermore, at the third iteration and at the bit error rate (BER) of 10^-12, its net coding gain (NCG) was respectively 0.46 dB and 0.43 dB more than that of RS(255,239)+CSOC(k0/n0=6/7,J=8) code and BCH(3860,3824)+BCH(2040,1930) code in ITU-T G.975.1. Therefore, the constructed RS(255,223)+BCH(2040,1930) concatenation code can be better suitable for optical communications.

Abstract: In order to improve the application effectiveness of cluster analysis in unsupervised image classification, a clustering algorithm based on density and adaptive density-reachable is designed and implemented. Compared with the classifying results of K-means and hierarchical method, it is evident that the algorithm has good effect on unsupervised image classification.

Abstract: This paper is focused on multiclass character segmentation for image of shopping receipt from POS machine, especially the Chinese characters. A secondary analysis method based on projection histogram is proposed, where the histogram is regarded as waveform signal, through filtering processing, it is to find trough point for the line segmentation. As for the word segmentation, this paper proposes rules for mergence of Chinese character components to solve issue about segmentation of Chinese characters with left and right components. The experimental results demonstrated that the segmentation accuracy is above 96%.

Abstract: This paper proposed an automatic exposure algorithm based on luminance histogram and region segmentation. The method ensures well exposure to the main object under the backlighting or excessive front-lighting conditions, and uses the characteristics of the luminance histogram to judge the scene condition. According to the luminance histogram, if the image under normal light conditions, the method compares the average luminance value of the image with the corresponding reference target brightness value to adjust exposure compensation. If the image under special conditions, the average brightness value will be calculated using fixed-partition method and exposure compensation will be adjusted. The paper combines auto-exposure and auto-gain control to adjust the exposure compensation. As it turns out, this method in a variety of light conditions can achieve well exposure.

Abstract: In this paper, we demonstrate a novel receiver in visible light communication system based on RGB LEDs. It contains three major parts the collimating lens, the spectro-device and the photodetector. The mixed RGB signal lights are captured, separated and received by the collimating lens the spectro-device and the photodetector respectively. Through the adjustment of the collimating lens, the receiver can receive enough light even if the distance between the signal light source and the receiver is changed. The receiver has the advantages of strong mobility and strong ability of receiving signal light. Based on the designed receiver the high-speed visible light communication system using RGB wavelength division multiplexing technology can have better performance.

Abstract: In this paper, we introduce an optimal control theory (OCT) based method for design of broadband excitation pulse with limited radio frequency (RF) amplitude in nuclear magnetic resonance (NMR). The capability of the optimized pulse was verified by the following design criteria: the state transfer of 1H fromtoover resonance offsets of, the pulse duration is 1ms with maximum RF amplitude of 10 kHz. The simulation result demonstrates that the optimal control-based shaped pulse is much more adaptable to broadband excitation, providing a better performance than traditional hard pulse.

Abstract: We propose a practical image retrieval scheme to retrieve images efficiently. The proposed scheme transfers each image to a color sequence using straightforward 8 rules. Subsequently, using the color sequences to compare the images, namely color sequences comparison. We succeed in transferring the image retrieval problem to sequences comparison and subsequently using the color sequences comparison along with the texture feature of Edge Histogram Descriptor to compare the images of database. We succeed in transferring the image retrieval problem to quantized code comparison. Thus the computational complexity is decreased obviously. Our results illustrate it has virtues both of the content based image retrieval system and a text based image retrieval system.