Li Shenghong

New multi-pattern matching algorithm

The traditional multiple pattern matching algorithm, deterministic finite state automata, is implemented by tree structure. A new algorithm is proposed by substituting sequential binary tree for traditional tree. It is proved by experiment that the algorithm has three features: its construction process is quick, its cost of memory is small. At the same time, its searching process is as quick as the traditional algorithm. The algorithm is suitable for the application which requires preprocessing the patterns dynamically.

A novel text subject extraction method

Word segmentation or word extraction is always the first step of subject extraction. For no intervals between words, word segmentation of Chinese text is rather complicated. A novel text subject extraction method based on contextual cooccurrence is put forward, and an approach of extracting subject sentence from Chinese text using character contextual cooccurrence data is described. The new approach has fast speed and can skip the segmentation. It also can be applied in multistyle text. The result of three experiments shows that the approach gains high accuracy in multistyle text, 77.19% in news text. Comparative experiment shows that there was no loss in accuracy.

Harmonic retrieval in colored ARMA noise

We propose a new approach to harmonic retrieval in colored ARMA noise. A suitable filter is first used to remove all the sharp power spectrum peaks of the noisy observed process, then some kinds of cross correlation is employed to identify the noise characteristics. After filtering the noisy observed process with the identified noise characteristics again, SVD-TLS method can be applied to retrieve the harmonics. The proposed approach can be used to retrieve real-valued harmonic signals in colored ARMA noise with no restrictions on the phase coupling of harmonics and the distribution of the noise. Simulation examples show its effectiveness.

Image Splicing Detection Based on Improved Markov Model

Digital image splicing detection is a new and important subject in image forensics. Research shows that Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) based Markov features are effective for image splicing detection. However, the state selection in the traditional Markov model was simply rounding the parameters and taking threshold value, which has not exploited the parameter distribute information. In this paper, a novel Markov state selection method is proposed. The approach matches states with parameters evenly according to fixed ratio calculated by pre-set state numbers. Experiments show that the improved Markov model achieves higher recognition accuracy rate compared with the traditional Markov model with the same feature dimension.

Neural network based scheduling for variable-length packets in Gigabit router with crossbar switch fabric and input queuing

A high-speed and effective packet scheduling method is crucial to the performance of Gigabit routers. The paper studies the variable-length packet scheduling problem in Gigabit router with crossbar switch fabric and input queuing, and a scheduling method based on neural network is proposed. For the proposed method, a scheduling system structure fit for the variable-length packet case is presented first, then some rules for scheduling are given. At last, an optimal scheduling method using Hopfield neural network is proposed based on the rules. Furthermore, the paper discusses that the proposed method can be realized by hardware circuit. The simulation result shows the effectiveness of the proposed method.

Analysis and improvement of TCP congestion control mechanism based on global optimization model

Network flow control is formulated as a global optimization problem of user profit. A general global optimization flow control model is established. This model combined with the stochastic model of TCP is used to study the global rate allocation characteristic of TCP. Analysis shows when active queue management is used in network TCP rates tend to be allocated to maximize the aggregate of a user utility functionUs (called,Us fairness). The TCP throughput formula is derived An improved TCP congestion control mechanism is proposed. Simulations show its throughput is TCP friendly when competing with existing TCP and its rate change is smoother. Therefore, it is suitable to carry multimedia applications.

A new approach to VC routing in ATM networks

A new ant-algorithm-based routing approach is proposed for the VC routing problem with considering the comprehensive effect between the resource utilization and the load balance in ATM networks. In the approach, the backup paths are calculated first, and then an ant algorithm based on the ability of ants to find the shortest path between their nest and the food source during their searching food, is constructed to optimize the VC global route. Simulation results show that the proposed approach can realize VC routing effectively according to the current traffic states in the networks and the user-specified delay requirements.