Journal of Computer Applications

Deep Web data annotation method based on result schema

Ming LI XIU-lan LI

2011, 31(07): 1733-1736. DOI: 10.3724/SP.J.1087.2011.01733

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Comprehensive and accurate annotation of Deep Web data is the key technology to Deep Web data integration, but the existing methods of Deep Web data annotation are unavailable to effectively solve the problem. Therefore, an approach of Deep Web data annotation based on result schema was proposed. The paper, through analyzing Deep Web result pages and extracting structured data, completed data pretreatment work, then though establishing the correct semantic mapping relation between integrated result schema and staying annotation data, achieved correct annotation of Deep Web data. The experimental results over four real areas show that the proposed method can efficiently annotate Deep Web data.

Popularity forecast of movies based on data mining in content distributed/delivery network

Zhi-wei ZHOU Quan ZHENG Song Wang

2011, 31(07): 1737-1739. DOI: 10.3724/SP.J.1087.2011.01737

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The estimation of the content popularity in the Content Distributed/Delivery Network (CDN) system mainly relies on the experience of administrators, which implies strong subjectivity and cannot guarantee the Quality of Service (QoS). In the paper, the authors firstly preprocessed the data, and obtained the initial knowledge base to predict the film popularity. This paper used data mining techniques to learn the existing knowledge and predict the popularity of films. Thus, the films in the CDN system could be deployed more effectively and efficiently. The movie popularity predicted by Bayesian network classier was compared with the movie popularity predicted by decision tree. On the premise of the same correct classification rate and other classification parameters, the time taken to build model in the Bayesian network classifier can be shorter. Therefore, the Bayesian network classifier was preferred. The method can solve the inaccurate deployment caused by the administrators subjectivities and improve the efficiency of the CDN system.

Improved ranking algorithm based on pairwise method

CHENG Fan Hong ZHONG

2011, 31(07): 1740-1743. DOI: 10.3724/SP.J.1087.2011.01740

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The model learned by ranking algorithm based on traditional pairwise method does not work well by ranking measure, such as Normalized Discounted Cumulative Gain (NDCG). To solve this problem, a novel ranking algorithm is proposed. The algorithm uses the same train data as the traditional way, what different is defining a new object function faced to NDCG. For the problem that the function is non-smooth, difficult to directly optimize, the algorithm presents to use the cutting plane algorithm which not only solve the problem above but also make the number of iteration not depending on the training size. Experimental results on the benchmark datasets prove the effectiveness of the proposed algorithm.

Collaborative filtering algorithm based on real-time user feedback

He-gang FU Ran LI

2011, 31(07): 1744-1747. DOI: 10.3724/SP.J.1087.2011.01744

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Traditional memory-based collaborative filtering algorithm has the problem of bad scalability，while the model-based collaborative filtering algorithm，due to lagged updating hysterics，has the problem of bad recommendation. To solve the above problems，a collaborative filtering algorithm based on real-time users feedback was proposed，which achieved that recommender system can finish the real-time updating of the model data when a new rating was submitted by active user. Hence, recommender system can reflect the changing of user interest accurately. The experimental results indicate that the algorithm can improve the recommendation accuracy efficiently and reduce the recommendation time significantly.

Collaborative filtering recommendation algorithm based on user characteristics and item attributes

Zhi-min CHEN Zhi-qiang LI

2011, 31(07): 1748-1750. DOI: 10.3724/SP.J.1087.2011.01748

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Under the extremely sparse data environment, the traditional collaborative filtering algorithms only depenging on users rating data cannot achieve satisfactory recommended quality. A recommendation algorithm based on user characteristics and item attributes was provided. First, the timerelated interest degree was introduced in the process of user similarity calculation，which made a more accurate nearest neighbor set. While predicting the rating for the target user, the trust measure was used to reflect the neighbors contribution level for the ultimate recommendation. In addition, the users preference on item attribute instead of rating score was used to recommend the new items. The experimental results based on MovieLens data set show that the improved algorithm can solve the problem of coldstart and improve the accuracy of system recommendation significantly.

Mechanism of ontology semantic extension with constraints for information filtering

Jing-Jing YAN

2011, 31(07): 1751-1755. DOI: 10.3724/SP.J.1087.2011.01751

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An ontology based information filtering method is proposed in this paper. This approach describes formal semantic through ontology so that user’s original input query terms can be converted into ontology semantic extension formats with constraint rules. Furthermore, semantic vector definition of information and its right computation method are presented in order to achieve the semantic matching between user’s requirements and information. Finally, semantic similarity computation based information filtering is addressed. Experiments show that our information filtering algorithm is effective.

Testing of service-oriented software: a metamorphic testing approach

Xiao-li LU Wei-yun DONG

2011, 31(07): 1756-1758.

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During the process of service-oriented software testing, Oracle problem that the program result is unpredictable comes into existence frequently because of issues like the unknown communication partners before the service discovery and the potential existence of non-identical implementations of the same service. In this paper, based on the benefits of the SOA environments, Metamorphic Testing (MT) approach was applied in the phase of unit testing and integration testing of service-oriented software. Metamorphic Relation (MR) can be built according to the service properties. A metamorphic testing class can invoke relevant services to execute test cases and use their metamorphic relations to detect failures. Any violation of any relevant metamorphic relation indicates a failure.

Study on Software Reliability Growth Model Considering Environmental Difference

Xuan HAN Hang LEI

2011, 31(07): 1759-1761. DOI: 10.3724/SP.J.1087.2011.01759

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The failure intensity function will be misjudged in software reliability growth model(SRGM), because of the difference between the testing environment and the user environment. A logarithmic poisson model considering environment factor is proposed, which is based on the M-O logarithmic poisson execution time model, the representative of Musa execution-time models. It can represents the change law of the failure intensity function better, and the parameter estimating equations have been provided. The experimental results based on failure data sets, show that the proposed model has better curve fit than some of other models.

Software Reliability Prediction Based on the improved PSO-SVM Model

Xiao-nan ZHANG An-xin LIU Bin LIU Hong-mei ZHANG Xing Qing

2011, 31(07): 1762-1764. DOI: 10.3724/SP.J.1087.2011.01762

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The major disadvantages of the current software reliability models were discussed. And then based on analyzing classic PSO-SVM model and the characteristics of software reliability prediction, some measures of the improved PSO-SVM model were proposed and an improved model was established. Lastly, the simulation results show that compared with classic models，the improved model has better prediction precision，better generalization ability and lower dependence on the number of sample, which is more applicable for software reliability prediction.

Research of atomicity in workflow transaction

Ya-li YUAN Hong-mei CHEN

2011, 31(07): 1765-1768. DOI: 10.3724/SP.J.1087.2011.01765

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Traditional workflow management systems lack the abilities of handling transactions, thus cannot recover quickly enough. This paper introduced a prototype of transactional workflow by adding failure mode in modeling. When a task failed, the system could invoke the transactional algorithm with loosed atomicity to assure the data consistence, as well as decrease the work of participants. The experimental result shows that the workflow management system with transaction charactors can recover efficiently after failure.

Research and application of performance test on Web application system

Bin-wu HUI Ming-rui CHEN Deng-pan YANG

2011, 31(07): 1769-1772. DOI: 10.3724/SP.J.1087.2011.01769

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The performance test of software is to examine efficiency、resource occupation and stability etc，in order to verify system capacity，find defects in early and provides support for system performance tuning. This paper studies the architecture and performance characteristics of Web application system then proposed a general performance testing process model. Basing on the model we use HP’s automatic test tool LoadRunner implement testing on Evaluation Subsystem of City Management System.

Multi-task and multi-resource optimization scheduling of virus genetic algorithm

Jin-ping JI Xian-feng CHA

2011, 31(07): 1773-1775. DOI: 10.3724/SP.J.1087.2011.01773

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Based on the analysis of current research for multiple resources distribution scheduling between parallel execution multi-tasks, concerning the limitation of all kinds of available resources in the enterprise multi-task management, this paper first gave a mathematical description of the problem, and structures a mathematical model for multi-resource scheduling among multi-task, and uses the virus genetic algorithm to find the answers. The simulation results show that the algorithm can obtain a satisfactory solution for optimal allocation of resources under the premise of completing all tasks at a quicker speed.

Case-based reasoning engine model with variable feature weights and its calculation method

Zhe-jing HUANG Bin-qiang WANG Jian-hui ZHANG Lei HE

2011, 31(07): 1776-1780. DOI: 10.3724/SP.J.1087.2011.01776

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In the Case-Based Reasoning (CBR) case retrieving and matching, different cases are usually composed by different features. But most of the traditional CBR engines adopt fixed feature weights mode, which makes matching rate of whole system very low. To solve this problem, this paper proposed a CBR engine model with variable feature weights and brought interactive mode into feature weights calculating module. It calculated subjective weight based on group decisionmaking theory and proposed an adjustment method which used differences between a single expert and his group. It used similarity rough set theory to calculate objective weight in order to make results calculating more objective and accurate. At last, it designed composite weights adjustment algorithm which calculated the distance between the subjective weight and objective weight, considered the deviation degree of those two weights, then deduced weights adjustment coefficient, and get the final weight adjustment results. The calculation example and simulation analysis of network attack cases validate the effectiveness of the proposed method and prove this method has much better performance in different performance indexes.

Approach of classification mapping between international patent classification and chinese library classification based on machine learning

Xue-ru JIN Jian-dong QI Li-chen WANG Lin-zhi ZHOU

2011, 31(07): 1781-1784. DOI: 10.3724/SP.J.1087.2011.01781

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Patents and journals belong to different knowledge organization systems. To achieve the crossbrowsing and crossretrieval between journal literature and patents，the mapping problem between two classifications Chinese Library Classification (CLC) and International Patent Classification (IPC), must be addressed. According to the survey of the existing methods of classification mapping, this paper discussed a method to achieve the mapping between CLC and IPC based on machine learning. The learner was got by training the corpus identified by the CLC category, with which to classify the corpus identified by the IPC category. The mapping relations can be found after analyzing the classification results. And the comparison experiment proves the effectiveness of this method.

Improved K-nearest neighbor algorithm for feature union entropy

Jing ZHOU Jin-sheng LIU

2011, 31(07): 1785-1788. DOI: 10.3724/SP.J.1087.2011.01785

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Poor generalization of feature parameters classification and large category computation reduce the classification performace of K-Nearest Neighbor (KNN). An improved KNN based on union entropy under the attribute reduction condition was proposed. Firstly, the size of classification impact of data feature was measured by calculating the union entropy of two feature parameters relative to any two condition attributes, and the intrinsic relation was established between classified features and the specific classification process. Then, the method which reduced condition attributes according feature union entropy set was given. The theoretical analysis and the simulation experiment show that compared with the classical KNN, the improved algorithm has better classification performance.

Multi-objective particle swarm optimization algorithm based on the Pareto neighborhood crossover operation

Min QU YUE-lin GAO QIAO-yong JIANG

2011, 31(07): 1789-1792. DOI: 10.3724/SP.J.1087.2011.01789

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A multi-objective particle swarm optimization algorithm with Pareto neighborhood crossover operation (MPSOP) is proposed to solve the defect of local search for prrticle swarm optimization problems. MPSOP employs particle swarm optimization algorithm and Pareto neighborhood crossover operation to generate new population. A scaling factor used to balance contributions of particle swarm optimization algorithm and Pareto neighborhood crossover operation. Numerical experiments are compared with NSGA-II, SPEA2 and MOPSO on six benchmark problems. The numerical results show the effectiveness of the proposed MPSOP algorithm.

Application of neural networks and improved PSO algorithms to earthquake prediction

Yi-xin SU Jun SHEN Dan-hong ZHANG Xiao-fang HU

2011, 31(07): 1793-1796. DOI: 10.3724/SP.J.1087.2011.01793

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This paper proposed an earthquake prediction method based on neural networks and an improved particle swarm optimization algorithm. In this method, a feed forward neural network was applied to predict the level of earthquake, and a modified particle swarm optimization algorithm was applied to optimize the neural network model. In order to get weights of the optimal balance between the global search and local search, a Dynamic Mutational Particle Swarm Optimization (DMPSO) algorithm was designed by using the ideology of dynamic mutation. This algorithm was used to adjust weights of the feed forward neural network. The simulation results of the proposed method were compared with the simulation results of two feed forward networks with different training algorithms. The comparison results show that the prediction model with DMPSO has fastest convergence rate, the smallest prediction error and strongest generalization ability. In conclusion, the model with DMPSO is a good reference to the middle earthquake prediction.

Hardware/software partitioning based on improved simulated annealing algorithm

Ping XIAO Cheng XU Zhi-Mang YANG

2011, 31(07): 1797-1799. DOI: 10.3724/SP.J.1087.2011.01797

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Hardware/software partitioning is a key issue of embedded system design, and it has been proven to be a NP problem. Simulated annealing algorithm is a heuristic algorithm to solve this problem, but the simulated annealing algorithm has slow convergence. By improving the disturbance model and its annealing schedule, a new cost function method was proposed to accelerate the convergence speed. Compared to the classical simulated annealing algorithm and improved algorithms, the experimental results show that the new algorithm significantly reduces the running time and increases the probability of finding an approximately optimal solution.

Parallel algorithm for computing coefficients of periodic B-spline basis functions

Kai-ting ZHOU Li-xin ZHENG Fu-yong LIN

2011, 31(07): 1800-1803. DOI: 10.3724/SP.J.1087.2011.01800

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In the existing methods of periodic B-spline interpolation, coefficients of B-spline basis functions are determined by iterative algorithms. To overcome the weakness of the existing methods, new parallel algorithm for computing coefficients of B-spline basis functions were established. First, this paper established orthogonal B-spline basis and derived parallel algorithm for coefficients of orthogonal B-spline basis functions; and then derived parallel algorithm for coefficients of B-spline basis functions by using the relation between coefficients of orthogonal B-spline basis functions and coefficients of B-spline basis functions; at last this paper derived explicit formulas for both coefficients of B-spline basis functions and value of interpolated point with the 2nd, the 3rd and the 4th order periodic interpolating B-spline functions. The presented method retains the simplicity of B-spline basis functions while realizing fast parallel algorithm for coefficients of B-spline basis functions.

Self-adaptive step glowworm swarm optimization algorithm

Zhe OUYANG Yong-quan ZHOU

2011, 31(07): 1804-1807. DOI: 10.3724/SP.J.1087.2011.01804

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According to the problem that Glowworm Swarm Optimization (GSO) cannot acquire solutions exactly and converge slowly in the later period for solving the multimodal function，an improved GSO algorithm combined with luciferinfactor, which can adaptively adjust step, was proposed. The simulation results show that the improved Self-Adaptive Step Glowworm Swarm Optimization (ASGSO) can search for global optimization more quickly and precisely.

Heterogenous multi-core mechanism based on heterogeneity-aware static scheduling and heterogeneity-aware dynamic thread migration

Miao ZHANG De-xian ZHANG

2011, 31(07): 1808-1810. DOI: 10.3724/SP.J.1087.2011.01808

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Heterogeneous multi-core architecture is becoming more and more appreciated which reduces processor power dissipation significantly while the unbalanced load problem of heterogeneous multi-core processor may cause heterogeneous multi-core processor execute instability. In this paper we propose a mechanism based on HASS (heterogeneity-aware static scheduling )and (heterogeneity-aware dynamic thread migration) HADM to ensure the load balance among various different cores. Simulation experiment shows that the mechanism improves the executing performance and ensures the stability of heterogeneous multi-core processor.

Parameter optimization based multi-level partition of unity surface reconstruction

Pei-zhi WEN Ru-hua NING Jin-fang HUANG

2011, 31(07): 1811-1814. DOI: 10.3724/SP.J.1087.2011.01811

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In order to improve the accuracy and the stability of surface reconstruction with the multi-level partition of unity, an algorithm of multi-level partition of unity implicits based on parameter optimization was proposed. Firstly, analyzed the factors which the radius coefficient α of bounding spheres and the minimum Nmin of the bounding spheres influencing surface reconstruction. And then, the Nmin was adjusted by the condition of approximation implicit function and the α was adjusted by the requests of coverage density in different models. Finally, the method of surface reconstruction was more stable can be achieved by optimal combination selection of Nmin and α.The experiments proved that the method proposed was more stable and accurate in different models.

Focus depth extension for microscopic visual system based on wavelet analysis

Yu SONG Qing-ling LI

2011, 31(07): 1815-1817. DOI: 10.3724/SP.J.1087.2011.01815

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The main characteristic of optical microscopic visual is a short depth of focus, so it is difficult to obtain overall microscopic scene information. To overcome the problem, a wavelet analysis based strategy was proposed. It consists of two parts: the local information acquisition and the global information fusion. Firstly, based on the designed wavelet activity level measurement, a robust auto-focusing algorithm with new image sharpness function and fast global maximum searching strategy were designed to acquire local microscopic visual information. Secondly, an image wavelet activity level measurement based multi-focus images fusion scheme was presented. At last, the experimental results verify the validity of the proposed strategy.

Improved CenSurE detector and a new rapid descriptor based on gradient of summed image patch

Fang CHEN Yun-liang JIANG Yun-xi XU

2011, 31(07): 1818-1821. DOI: 10.3724/SP.J.1087.2011.01818

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This paper proposed a new, real-time and robust local feature and descriptor, which can be applied to computer vision field with high demands in real-time. Since CenSurE has extremely efficient computation,it has got wide attention. Due to its linear scales, the filter response signal is very sparse and cannot acquire high repeatability. Therefore, this paper modified the detector using logarithmic scale sampling, and obtained better performance. The new rapid descriptor was based on gradient of the summed image patch, called GSIP. The GSIP descriptor has superior performance. An extensive experimental evaluation was performed to show that the GSIP descriptor increases the distinctiveness of local image descriptors for image region matching and object recognition compared with the state-of-the-art SURF descriptor. Furthermore, compared with SURF, GSIP achieves a two-fold speed increase.

Accelerated algorithm of face detection based on dual-threshold cascade classifiers

Yan WANG Wei-jun GONG

2011, 31(07): 1822-1824. DOI: 10.3724/SP.J.1087.2011.01822

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The paper proposed an accelerating way of face detection based on dual-threshold cascade classifiers. First, it applied Gabor filter to extract the face-like features that were retained by template matching, then put eigenvectors extracted by the way of Principal Component Analysis (PCA) into the BP neural network as first classifier, then used dual-threshold to decide face or non-face on output end, and put the face or non-face of midway between up and down threshold into the AdaBoost classifier as the second classifier to decide. In this way, it can improve the detection rate and reduce the false rate while speeding up the detection speed. The experimental results prove that the precision of cascade classifier of face detection based on dual-threshold is superior to the classifier of single threshold.

Freeways detection from highresolution SAR images

Min LI

2011, 31(07): 1825-1826. DOI: 10.3724/SP.J.1087.2011.01825

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Concerning the characteristics of freeways in high-resolution Synthetic Aperture Radar (SAR) images, this paper proposed a detection algorithm for freeways. The algorithm mainly used multilevel nonlinear weighted mean median filtering algorithm and Hough transform. First, multilevel nonlinear weighted mean median filtering was run to the original highresolution SAR images. It can not only inhibit speckle noise more effectively but also preserve the geometrical features of the original SAR images. Then, Hough transform was run to filtered images to detect freeways, and superposed the detected information on the original SAR images to display. The experimental results indicate that the algorithm can detect freeways rapidly and effectively from highresolution SAR images got from different modes.

Environmental perception and the adaptive research in moving object detection

Yan ZHANG Ji-chang GUO Chen WANG

2011, 31(07): 1827-1830.

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In complicated environment, any changes will influence the accuracy of the object detection. Therefore, an algorithm was put forward, which combined the Generalized Gaussian Mixture Model (GGMM) and background subtraction to detect moving objects. The model has a flexibility to perceive environment and model the video background adaptively in the presence of environmental changes (such as radial gradient, background disturbance, shadows and noise). And when it has sudden illumination change，the model can resolve it quickly. In order to meet the realtime requirement, this algorithm adopted the principle, to update every other two frames. The experiments show that it can meet the realtime requirement and detect the moving object accurately.

Adaptive background update based on Gaussian mixture model under complex condition

Ming-zhi LI Zhi-qiang MA Yong SHAN Xiao-yan ZHANG

2011, 31(07): 1831-1834. DOI: 10.3724/SP.J.1087.2011.01831

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In view of the background update problems based on Gaussian Mixture Model (GMM), such as sudden illumination change, mutual transformation between target and background, a new background auto-adapted update algorithm was proposed in this paper. First, the algorithm distinguished whether the sudden change of illumination occurred according to the current tested target size, and took pertinent updating measures. If there is not sudden change of illumination, the backgrouds of backgroud region and target region were updated seperately. The update of the target region was mainly discussed, and the method that adjusted the background update rate of the target region according to the targets characteristic parameters, such as size, velocity of movement and match times was proposed. The simulation results show that the algorithm not only guarantees the integrity of target detection, but also improves the adaptation of model to background changes.

Improved adaptive median filtering algorithm

Bao-gui HUANG Zhen-tai LU Chun-mei MA Jing-xiu ZHAO

2011, 31(07): 1835-1837. DOI: 10.3724/SP.J.1087.2011.01835

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The size of median filtering window influences the capability of filter and 3×3 filtering window can preserve image details. An adaptive median filtering method was proposed. The extreme value point in 3×3 filter window was taken as candidate noise. If the candidate noise is extreme value in 7×7 window, then it is a sure noise. If the median value of 3×3 filter window is not noise, then the central noise would be replaced with the median value. The steps above were repeated until there was no noise replaced. If there still existed large noise cluster, the noise would be replaced with the mean of the three signals near it. The experimental results show that the method can denoise impulse noise and protect the image details effectively.

Improved algorithm of monocular camera calibration for vision navigation

Lei ZHOU Guo-quan REN Dong-wei LI

2011, 31(07): 1838-1840. DOI: 10.3724/SP.J.1087.2011.01838

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One camera is used in the autonomous navigation system of intelligent vehicle, and camera calibration is the key and precondition of the intelligent vehicles correct and safe navigation. Through the study of ideal model and actual model of camera, an improved calibration method was proposed. In the process of obtaining internal and external parameters of the camera, this algorithm combined the advantages of both linear and nonlinear calibration, which calibrated parts of the parameters of camera firstly and then considered simplifying the distortion model. The nonlinear equation systems can be changed into linear equation systems. Additionally, all the parameters of camera were acquired through many times iteration. On the one hand, it can ensure the calibration accuracy. On the other hand, it reduces the complexity of the cameras actual model. The experimental results show that the method can meet the requirements of vision navigation.

Trademark Retrieval Algorithm Based on Sift Feature and Corner Feature

San-hu WANG Wang-shu YAO Xing-hong LING

2011, 31(07): 1841-1843. DOI: 10.3724/SP.J.1087.2011.01841

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The Scale-Invariant Feature Transform (SIFT) algorithm for trademark retrieval may fail to detect some reversal and highly similar images. To solve this problem, a new algorithm based on SIFT descriptor and corner feature was proposed. This method used corner feature to make up for the lack of SIFT. The experimental results show that this method not only contains the character of SIFT descriptor like robustness against noise, but also improves the ability for description of image shape, so the method shows a better retrieval performance than other methods.

Text detection from images with complex background by ant colony optimization algorithm

Min-hua LI Meng BAI

2011, 31(07): 1844-1846. DOI: 10.3724/SP.J.1087.2011.01844

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To detect text from images with different backgrounds, a text detection method with ant colony optimization algorithm was proposed. Before text detection, an ant colony optimization algorithm was adopted to detect image edges, and then features were extracted from the edge image. Afterwards, a coarsetofine strategy was applied to detect the text lines from image. Finally, the experimental results show that the proposed method achieves more precise detection than Soblebased, Cannybased and othor two detection methods.

Pornographic images filtering model based on high-level semantic bag-of-visual-words

Lin-tao LV Cheng-xuan ZHAO Jin SHANG Yu-xiang YANG

2011, 31(07): 1847-1849. DOI: 10.3724/SP.J.1087.2011.01847

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Current Pornographic images filtering algorithms have some problems, such as the high false positive rate toward the bikinis images and insufficiency of filtering pornographic images with pornographic actions. The paper proposes a novel pornographic image filtering model based on High-level Semantic Bag-Of-Visual-Words. Firstly, local feature points in sex scene are detected using the SURF algorithm and then high-level semantic dictionary is constructed by fusing the context of the visual vocabularies and spatial-related high-level semantic features of pornographic images. Experimental results show that the model has an accuracy up to 87.6% when testing the multi-person pornographic images, which is significantly higher than the existing pornographic image filtering algorithm based on Bag-Of-Visual-Words.

Fast image matching method based on eigen-scene

Lei YANG Xiu-juan GUO

2011, 31(07): 1850-1852. DOI: 10.3724/SP.J.1087.2011.01850

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In this paper, a new method based on eigenscene for fast image matching was presented, and it could solve the problem that mainstream matching algorithm with local features cannot describe the global features. By extracting scene images, the eigenscene using Principal Component Analysis (PCA) could be reconstructed, and then it could be used for matching scope division. In the divided matching scope, SURF algorithm was used to match fast local features. The experimental results indicate this method combines the large scale global features and scale invariant local features so that the discrimination ability is enhanced for similar object. The robustness and timeliness of this method achieve good balance so that it extends the application fields of mainstream matching method with local features. In the end, improvement direction is suggested for this paper, which shows the scalability of this method.

Multiple ellipses detection based on curve arc segmentation of edge

Nan-nan LI Rong-sheng LU Shuai LI Yan XU Yan-qiong SHI

2011, 31(07): 1853-1855. DOI: 10.3724/SP.J.1087.2011.01853

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In this paper, a new efficient algorithm for ellipse detection was proposed, which was based on edge grouping, different from standard Hough transform. Firstly, It separated edge boundary into different arcs at the intersections, divided those arcs into two categories: the long and the short and sorted the two categories at non-increasing sequence, then estimated the parameters of the ellipses using least square fitting method with arcs which may belong to the same ellipse; at last testified whether ellipses coming from the front steps are real ones. The method has been tested on synthetic and real-world images containing both complete and incomplete ellipses. The outcome demonstrates that the algorithm is robust, accurate and effective.

Compression algorithm based on half-length of the binary stream

Jian GAO Wan LIU Ao SONG Zhong-yuan WANG Yao CHEN

2011, 31(07): 1856-1858. DOI: 10.3724/SP.J.1087.2011.01856

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A binary code of the compression algorithm is presented. The black and white run-lengths in the binary code stream are compressed halved, which could also be progressed by selecting different initial length according to the different length distribution. Numerical experiments show that the algorithm has a better compression efficiency compare with that of the traditional methods of run-length code, and has good application value.

Attack analysis and improvement on two DL-based digital signature schemes

Han FAN Shao-wu ZHANG

2011, 31(07): 1859-1861. DOI: 10.3724/SP.J.1087.2011.01859

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The method of identical base construction attack on digital signature scheme proposed by CHEN NINGYU et al. (CHEN NING-YU, GU YONG-GEN, SU XIAO-PING. Identical base construction attack on digital signature scheme. Journal of Computer Applications,2010,30(4):1042-1044) was used to carry out attack analysis on the two DLbased digital signature schemes. The improved proxy blind signature scheme proposed by LI FANGWEI et al. (LI FANG-WEI，TAN LI-PING，QIU CHENG-GANG.A proxy blind signature scheme based on DLP. Journal of Electronic Science and Technology, 2008,37(2)：172-174.) was analytical attacked. It was found out that, using the forgery attack, a dishonest proxy signer could fake proxy signature receiver to generate valid proxy blind signature. A DL-based signature scheme without certificates proposed by Lein Harn et al. (HARN L, REN JIAN, LIN CHANGLU. Design of DLbased certificateless digital signatures. Journal of Systems and Software，2009，82(5):789-793) was analyzed and it was found that the dishonest Private Key Generator (PKG) can forge the users private key. The cause of the attack was analyzed and the attack methods and the improvement measures were presented.

Password-based Authenticated Key Agreement Scheme with Mutual Anonymity for Trusted Computation

Chang-sheng ZHU Qing-rong WANG Lai-cheng CAO

2011, 31(07): 1862-1867. DOI: 10.3724/SP.J.1087.2011.01862

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How to keep mutual anonymity between two entities is one of the critical issues for Trusted Computation; According to the characteristics of TC, an efficient password-based authenticated key exchange scheme was presented. Adopting threshold cryptography and fuzzy ID set, the scheme achieves the mutual anonymity between user and server sharing ID set. On the premise of secure Hashing, the analysis and the proven procedure based on the ROM (random oracle model) show this scheme is secure against dictionary attack and Resource-Depletion DoS (denial-of-service) attack under the computational Diffie-Hellman intractability assumption. This scheme effectively preserves the user’s privacy and server's privacy, compared with other schemes including VIET et al.’s scheme, it is more efficient.

Network coding signature scheme with limitation of nodes to check news

Fan FENG Cai-fen WANG Hai LUO Zhi-xuan YU

2011, 31(07): 1868-1871. DOI: 10.3724/SP.J.1087.2011.01868

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The existing network coding research focuses on the increase of the transmission efficiency of information on the network yet ignoring the informations overflow in the transmission caused by the network coding, which poses a threat to information security and even all message in the networks can be revealed by network nodes. In order to solve this problem, a new method was designed. Based on the different number of information nodes needed to check in different network environments, there are two solutions: one is only a few nodes, using the public key signature of receiving information node, can check information. Meanwhile only the nodes with the private key corresponds to the public key can decrypt and get information. The other one is communication between multiple nodes. In order to avoid that the node with no permission checks information, session keys should be established between communication nodes and be used to transfer the information. The new scheme limits the nodes to check the information though the authority, and consequently ensures the security of information in the network. The usage of network coding in new scheme effectively improves the efficiency of information transmission while assuring the safety of transferring information in the network.

Enhanced key distribution scheme based on grid for wireless sensor networks

You-nan YUAN Lin YOU

2011, 31(07): 1872-1875. DOI: 10.3724/SP.J.1087.2011.01872

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Concerning the nodes’ limited storage in the wireless sensor networks, an enhanced key distribution scheme based on grid was proposed for wireless sensor networks. The paper constructed a new key distribution scheme for key pools and improved the probability of local connectivity. At the same time, the schemes security was doubly increased by the use of a hash function to protect key information stored in the nodes. Compared with Du’s and E-G’s schemes, this experimental result shows that the proposed scheme has better performance on the local connectivity probability and security.

Reputation model based pair-wise key establishment algorithm for sensor networks

Fen-hua CHENG

2011, 31(07): 1876-1879. DOI: 10.3724/SP.J.1087.2011.01876

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Based on the key pre-distribution scheme, a new pair-wise key establishment method was proposed for sensor networks, in which each node was pre-assigned with an initial global key before deployment. And after deployment, the node can dynamically establish different one-hop pair-wise key on the basis of the pre-assigned global initial key. The theoretical analysis and simulation results show that the new algorithm has better probability of direct and indirect pair-wise key establishment than the traditional random pair-wise key establishing scheme for sensor networks.

Dynamic classification of trust for Web services

Yan CHANG

2011, 31(07): 1880-1883. DOI: 10.3724/SP.J.1087.2011.01880

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Based on existing research about classification of trust, the inaccuracy of trust classification for web services is analyzed and plan for classifying trust dynamically is put forward. From the angle of rationality and flexibility of defining trust attributes, intuitionistic fuzzy number is used to describe trust signature. Inherent capability, security characteristic and reputation are considered as the main signature to describe trust. Contribution degree of Inherent capability, security characteristic and reputation are calculated. Similarity matrix of trust intuitionistic fuzzy sets is constructed. Intuitionistic fuzzy equivalent matrix is got by calculating transitive closure. And trust classification is obtained by defining threshold cutting matrix. Validity and accuracy of dynamic classification is verified.

Static eparation of duty policy base on mutually exclusive role constraints

Ting WANG Xing-yuan CHEN Bin ZHANG Zhi-yu REN Lu WANG

2011, 31(07): 1884-1886. DOI: 10.3724/SP.J.1087.2011.01884

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Static Separation Of Duty (SSOD) is an important principle of information system security. In Role-Based Access Control (RBAC), it is difficult to enforce 2-n SSOD policy directly based on 2-2 Static Mutually Exclusive Role (SMER) constraints. In this paper, the necessary and sufficient conditions of realizing 2-n SSOD policy based on 2-2 SMER constraints were proposed and proved. The sufficient condition proposed was less restrictive than the existing research and allowed more flexible privilege assignment. By the operation rules of authorization management, the sufficient condition was kept and the satisfaction of 2-n SSOD policy during the dynamic change of application environment could be maintained. The application example shows that the method is correct and effective.

Weighted trust computation method based on behaviors of users

Qi-hong LIU Xiao-nian WU Li YANG

2011, 31(07): 1887-1890. DOI: 10.3724/SP.J.1087.2011.01887

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In trust computing, recommendation trust has very strong subjectivity and some aggressive behaviors like deception and slander. Those factors will conceal the authenticity of behaviors of user who is recommended and threat the system security. To address the problem, this paper proposed a weighted trust computing method based on user’s behaviors. The time attribute of feedback information was identified by using time attenuation. And the trustworthiness of users was computed based on directness trust and recommendation trust with different weights. Also, this paper introduced Feedback credibility to evaluate the authenticity of recommendation trust. Simulation experiments show that this method has better adaptability to the dynamics of trust. It can reduce effectively the impact of malicious recommended trust, and compute accurately the trust of users according to user’s behaviors, which provide reliable information to correctly make security decision for the system.

Improved SIR model of computer virus propagation in the network

Li-ping FENG Hong-bin WANG Su-qin FENG

2011, 31(07): 1891-1893. DOI: 10.3724/SP.J.1087.2011.01891

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By analyzing the deficiency of the existing network virus models, referring to the reality and considering the infectious disease models in biology, an improved Susceptible-Infected-Removed (SIR) computer virus propagation model with pre-immune measures was put forward. The authors considered the varying number of nodes and analyzed its impact on the spread of the virus in the network. In addition, several related dynamic properties were analyzed. The numerical simulation results demonstrate that improving pre-immune rate and controlling the nodes flow in the network can effectively constrain virus prevalence. And this model has inspiration to predict and prevent from computer virus propagation.

Variable length gram based file type identification algorithm

Ding CAO Jun-yong LUO Mei-juan YIN

2011, 31(07): 1894-1897. DOI: 10.3724/SP.J.1087.2011.01894

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Fast and accurate identification of the true type of an arbitrary file is very important in information security. Concerning the problems of current contentbased file type identification algorithms, variablelength gram was introduced for describing statistic characteristics of files binary content, and a new evaluation function combining gram divergence, stability and conditional width was adopted for feature selection for structured file types. This algorithm does not rely on the structure and key words of any specific file types, which allows the approach to be applied more widely. The experimental results show that the proposed approach improves the precision and recall of file type identification.

Intrusion detection method based on graph clustering algorithm

Guo-hui WANG Guo-yuan LIN

2011, 31(07): 1898-1900. DOI: 10.3724/SP.J.1087.2011.01898

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Concerning the defects of the current clustering algorithm for its dependence only on the initial clustering center and failure in exactly distinguishing classes of non-concave shape, this paper applied the knowledge of group learning into the clustering algorithm and proposed the anomaly intrusion detection algorithm P-BFS based on graph clustering. In order to obtain more correct classification model, this algorithm introduced a measurement method of data points similarity based on the approximate function. The experimental results suggest the advantages of the application of the graph clustering algorithm in the intrusion detection system. In addition, it indicates that compared with the classical K-means clustering algorithm, P-BFS has better performance.

Classification of packed PE files based on data mining

Yue-hua ZHAO Yi ZHANG Hong-ping YAN

2011, 31(07): 1901-1903. DOI: 10.3724/SP.J.1087.2011.01901

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The proliferation of malicious code makes automatic malicious code detection an inevitable trend. Packed Portable Executable (PE) files identification is a necessary step of malicious code analysis. The paper presented an automatic identification method based on data mining, through which feature was extracted from PE files. The paper used classification algorithms and selected features to detect packed PE files. The test results show that the identification rate is 98.7% when using J48 classifier.

Multi-level proxy blind signature scheme based on discrete logarithm problem

Wan WANG Wei-zhang DU

2011, 31(07): 1904-1905. DOI: 10.3724/SP.J.1087.2011.01904

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By analyzing Caimian’s multi-level proxy signature scheme (CAI MIAN,KANG LI.A secure multiple grade proxy signature scheme. Journal of the Graduate School of the Chinese Academy of Sciences, 2006，23(5)：653-659), this paper proposed a thought of building an ordinary multilevel proxy signature scheme and made a comparison with the original scheme, and also proposed a new multi-level proxy blind signature scheme by using the thought of multi-level proxy signature scheme. the new scheme overcame original signer forgery attack in the proxy part and had strong blind property in the blind signature part.

Niederreiter public-key cryptosystem based on QC-LDPC

Lei-Xin YANG Wei-zhang DU

2011, 31(07): 1906-1908. DOI: 10.3724/SP.J.1087.2011.01906

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A Niederreiter public-key cryptosystem based on QC-LDPC codes was proposed. As the check matrix of QC-LDPC codes is spare，who has the structure of circulative blocks and high error correction capability, compared with other public-key cryptosystem，the key sizes of the new cryptosystem is reduced and transmission rate is improved. A new parity-check matrix was mapped by invertible transformation matrix Q with diagonal form. The sparse characteristic of is countervailed. Through analyzing existing attacking methods，the security of the cryptosystem is confirmed to be improved.

Improved algorithm based on Henon Hyperchaotic system for image encryption

Hong-hui LE Tao LI Lei SHI

2011, 31(07): 1909-1911. DOI: 10.3724/SP.J.1087.2011.01909

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To enhance the security of image encryption algorithm in chaotic systems, a new algorithm based on the combination of MD5 and chaotic system was proposed. Allowing MD5 value of original image to participate in the initialization of Henon hyperchaotic system, the algorithm increased the sensitivity of original image and was much more complex than the ordinary system. In addition, the altered algorithm of binary code stream sequence generation could lead to dynamic change of block length so as to further disrupt the original characteristic of chaotic system and the packet characteristics of the code stream. This algorithm could resist chosen plaintext attack, differential attack and partition attack effectively, which has been verified by analysis and experiment.

Security analysis and improvement of KNXnet/IP protocol

Jun-chang LIU Xi-huang ZHANG

2011, 31(07): 1912-1916. DOI: 10.3724/SP.J.1087.2011.01912

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As the extended application of European Installation Bus (EIB) protocol, KNXnet/IP protocol increases the transmission speed of EIB system and fulfills the requirement of intelligent management. But the security of KNXnet/IP protocol is heavily threatened in the securitycritical environment. A security protocol was proposed after analyzing the security mechanism of IP network and embedded system. The security protocol used selfdefined key sets distribution protocol based on asymmetric cryptography algorithm and used symmetric cryptography algorithm for communication. It provides transparent data transmission and only needs very few changes of the primary architecture. The implementation proves the feasibility and security of the security approach.

Improved data hiding scheme based on modulus function

Kai-hui LIU Jiang-feng XU

2011, 31(07): 1917-1919. DOI: 10.3724/SP.J.1087.2011.01917

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The new method proposed by Lee et al. (LEE C F, CHEN H L. A novel data hiding scheme based on modulus function. The Journal of Systems and Software, 2010, 83(5): 832-843) was based on modulus function. In this method, each pixel can carry a maximum of 4 bits with an acceptable visual quality. When each pixel is embedded with 4 bits, the quality of stegoimages is much worse; as a result, this may catch the attention of attackers. Consequently, this paper improved the method, which narrowed the range that pixels changed. The theoretical analysis and simulation results show that the new method not only keeps the various advantages of original method, but also makes the Peak Signal-toNoise Ratio (PSNR) value increase 1.5~3.5 dB. Thus, it can raise imperceptibility and the ability resisting RS attack of stego-images.

Analysis on characteristics of packet train measurement methods based on queuing model

Xiao-tao HE Wen-Wei LI

2011, 31(07): 1920-1923. DOI: 10.3724/SP.J.1087.2011.01920

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Understanding the queuing characteristics of probing packet trains is the basis for designing bandwidth measurement methods. Based on a single hop queuing model of routers, the queuing characteristics of probing packet trains under the impact of cross traffic were studied. Four typical queuing behaviors of packet trains which have different packet delay variance distribution, i.e. no cross traffic queuing, short cross traffic queuing, long cross traffic queuing, and multiple cross traffic queuing, were analyzed, with different degrees of cross traffic load. The experiments simulated different degrees of cross traffic load, by setting different probing packet train sending rates, and found that the packet delay variance of probing packet trains has different distribution characteristics, which is consistent with the analytical results.

Mobile Agent-based routing optimization algorithm in large-scale wireless sensor networks

Qiang ZHOU Xun-xue CUI Gui-lin CHEN

2011, 31(07): 1924-1927. DOI: 10.3724/SP.J.1087.2011.01924

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The common routing algorithms tremendously dissipate energy in largescale wireless sensor networks, which goes against the maximization of the network lifetime. A routing model about mobile Agent in sensor networks was drawn out, and then an optimization problem of mobile Agent static route was derived. A chaotic simulated annealing with memory ability and various neighborhood search methods were proposed to optimize the route of mobile Agent in largescale sensor network. The theoretical analysis and experimental results show that the proposed algorithm is superior to other intelligent algorithms in terms of the solutions, the convergence speed, and the computation time. It proves that the proposed approach has obviously prolonged the network lifetime.

Routing protocol in multi-channel wireless mesh networks

Yi PENG Lei ZHU Ling LIU

2011, 31(07): 1928-1930. DOI: 10.3724/SP.J.1087.2011.01928

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In order to solve the problem that channel resource cannot be fully utilized by single-path routing protocol in multi-channel wireless mesh networks, a Parallel Multi-path Routing Protocol (PMRP) based on congestion control was proposed. This protocol spread a data flow over multiple paths and only re-found new route after all routes have broken. It prevented the congested node to transmit new data flow by utilizing congestion control mechanism. The simulation results demonstrate that, compared with Ad hoc On-demand Distance Vector Routing (AODV) routing protocol, PMRP can reduce the average end to end delay, and improve the data packet delivery ratio and the network throughput effectively.

Research of AODV routing protocol based on neighbor cache

Shi-bao LI Li HONG

2011, 31(07): 1931-1933. DOI: 10.3724/SP.J.1087.2011.01931

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In Mobile Ad Hoc Networks (MANET), the routing overhead was heavy and routing latency was long by using conventional algorithms of route discovery such as flooding and Expanding Ring Search (ERS). In order to improve the performance of routing protocol, a scheme of route discovery was provided based on the neighbor cache. Neighbor information was extracted from data packets, and neighbor cache table was established to store historical neighbor records. And then the approach of route discovery included two stages: 1) Found the node meeting the destination node before a short time; 2) Started new ERS. The simulation results show that the new scheme significantly improves performance of the protocol under many kinds of simulation scenarios. The routing overhead is saved and the endtoend delay of the packet is reduced. At the same time, the new scheme is also easy to implement.

Bottleneck bandwidth measurement and localization based on meltable packet train

Min-zheng JIA Yuan-zhong ZHU Zhen-wei YU Ying ZHANG

2011, 31(07): 1934-1938.

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The paper analyzed the current measurement technologies and the existing localization methods of bottleneck bandwidth. Based on the analysis and comparison of their advantages and disadvantages, the paper put forward a new method of bottleneck bandwidth measurement and localization on the basis of meltable packet train method. The method can measure bottleneck bandwidth and localize it at the same time, which reduces the times and load of measurement effectively. In addition, the paper also proves the validity of the method from the theory and simulation experiment, and points out its advantages compared with other methods.

Bottleneck nodes in wireless sensor networks based on mobile sensors

Ya-ping DENG Chuan-ping WU

2011, 31(07): 1939-1943. DOI: 10.3724/SP.J.1087.2011.01939

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"Bottleneck Nodes" are those connecting two or more isolated areas because of the random deployment. Compared with other nodes, these nodes are more important to the lifetime of the whole network. The paper proposed a distributed cascading movement solution. This solution can reduce the distance and save the energy by moving nodes, and it also reduced the time to initialize the network coverage. The solution can balance the networks communications and increase the networks lifetime by moving some nodes to its proximity. The simulation results verify that the proposed solution outperforms others in terms of network lifetime, energy consumption and the time of node relocation.

Improvement on location error and coverage rate in DV-Hop algorithm

Jing ZHANG Dun CAO Ming FU Zi-qi CHEN

2011, 31(07): 1944-1947. DOI: 10.3724/SP.J.1087.2011.01944

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An improved DV-Hop localization algorithm was proposed by analyzing the deficiencies of rang-free DV-Hop algorithm in terms of localization accuracy and coverage rate. It has been set that the beacon nodes information only within a limited number of hops could be received by the unknown nodes, and only through the collinearity inspection the effectiveness of beacon nodes could be verified, and the nodes with a number of three or more can take part in locating. The minimum mean square error criteria, normalized weighting and Total Least Squares (TLS) methods were used to locate the unknown nodes respectively. Then the located unknown nodes were upgraded to beacon nodes, with the initial positioning beacon nodes to locate other unknown nodes. The simulation results show that compared with the original algorithm and the existing improved algorithm, this improved algorithm has significantly improved the localization accuracy and the coverage rate.

Adaptive subcarrier allocation of multiuser STBC-OFDM systems in correlated channels

Qiang LI Cheng-xin LI Yu-qing HUANG Yuan-cheng YAO

2011, 31(07): 1948-1951. DOI: 10.3724/SP.J.1087.2011.01948

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With the optimization goal of minimizing the total transmit power, an adaptive subcarrier allocation algorithm based on partial Channel State Information (CSI) under the condition of spatially correlated Rayleigh fading channels was proposed for multiuser STBC-OFDM downlink systems. In the course of algorithm implementation, the Kronecker model was used to express spatially correlated Multiple-Input Multiple-Out-put (MIMO) rayleigh fading channels of each subcarrier, and the dynamic CSIT (CSI at the Transmit) model was utilized to describe the process of CSI feedback; thus, the corresponding subcarrier allocation criteria could be deduced by means of the basic principles of Space-Time Block Code (STBC). The experimental results show that the proposed algorithm not only can effectively reflect system performance effects of the correlation coefficients of antenna correlation matrix and the parameters of delayed feedback, but also has good performance in contrast to subcarrier allocation without CSIT.

Cascading failure in coupled map lattices with directed network

Xiu-juan MA Xiang-fu MA Hai-xing ZHAO

2011, 31(07): 1952-1955.

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There are a large number of directed networks in the real world. According to a directional edge in the network, a cascading failure model was proposed which is suitable to describe the coupled map lattices with directed network. In this paper, using simulation methods, the cascading failures with BA (Barabási-Albert) scale free and ER (Erds-Rényi) random graph directed networks in this model was researched. Two attack strategies: deliberate attack and random attack were adopted in this fixed node number network, and relevant data were recorded. By analyzing the data, following conclusions can be made: 1) the cascading failures are much easier to occur in directed network than in undirected network; 2) when the networks are attacked, directed networks are more vulnerable than undirected networks; 3) in ER random graph networks, there is linear relationship among four thresholds with fault size increasing when network faults occur.

Adaptive media playout algorithm for H.264 scalable video streaming

Xiao-Feng LI Hong-sheng LIU Tong-ju RENG

2011, 31(07): 1956-1958. DOI: 10.3724/SP.J.1087.2011.01956

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To cope with the variation of network conditions in scalable video streaming, a new Adaptive Media Playout (AMP) algorithm was proposed which predicates the risk of playout outage and buffer overflow and adjusts the frame rate in advance. The algorithm estimated the throughput of network and the lengths of frames in the video’s GOP structure for risk predication, realized adjustments in K steps for good smoothness and speed, and reduced quality loss of the video by exploiting the scalability of SVC stream. The simulation results show that the proposed algorithm outperforms the existing smooth and conventional AMP algorithms in outage suppressing, overflow processing and jitter performance.

Application-layer multicast algorithm based on maximum interference network coding

Yong-guang LIU Jian ZHANG Ruo-he YAO

2011, 31(07): 1959-1961. DOI: 10.3724/SP.J.1087.2011.01959

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The application-layer multicast in end-system has overwhelming advantages compared with network-layer multicast. For improving the efficiency and performance of application-layer multicast, a multicast algorithm based on maximum interference network coding was presented. After adopting network coding, the new algorithm selected the maximum interference paths from source to every destination to improve coding efficiency and save network bandwidth. The simulations show that compared with non-coding multicast and simple network coding multicast algorithm, the new algorithm performs better in network throughout put and resource utilization.

Approximation algorithm for minimum connected dominating set in unit disk graphs

Xue-feng ZHAO

2011, 31(07): 1962-1965. DOI: 10.3724/SP.J.1087.2011.01962

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Minimum Connected Dominating Set (MCDS) problem is a classical optimization issue in the design of wireless networks. For the construction of MCDS in the Unit Disk Graph (UDG) to model wireless sensor networks, an efficient approximation algorithm, DDT, was proposed based on distributed greedy strategy. In each round, it repeatedly selected a node to link a determined node according to weights and state information among one-hop neighborhood, and finally, found a dominating tree for the graph. The maximum node degree in the dominating tree was studied using probabilistic method. By analyzing the relationship between the size of the maximal independent set and the minimum connected dominating set, the algorithm produced a new approximation ratio. The experimental results show the superiority of the DDT algorithm over other existing distributed algorithms in terms of the CDS size.

Network selection for wireless heterogeneous networks

Xu-bin ZENG Ling YUAN Bo-wen KONG

2011, 31(07): 1966-1970. DOI: 10.3724/SP.J.1087.2011.01966

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In heterogeneous networks, the result of network selection should come out according to subjective factors and objective factors, i.e. the users preferences and network objective attributes. But in limited scheme multi-objective decision-making of comprehensive evaluation method, Analytic Hierarchy Process (AHP) has the characteristics of strong subjectivity, the characteristics of the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is true, intuitive, and reliable. Therefore, concerning the features of the two methods, in the network selection issue, the user preference aspects in the choice of AHP method, network status using TOPSIS method, a kind of user preferences and network status collaborative judgment network selection algorithm was puts forward. The simulation results show that, without considering load conditions, the proposed algorithm can effectively choose the suitable network for mobile terminal current business.

Comparative analysis on three ultra wideband chip design methods

Liang ZHAO Liang JIN Zhong-heng JI Jin-yu CHEN Shuang-ping LIU

2011, 31(07): 1971-1975. DOI: 10.3724/SP.J.1087.2011.01971

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At present, in consideration of the carrier mode, the chip design methods of ultra wideband systems mainly involve no-carrier ultra wideband, single carrier ultra wideband and multi-carrier ultra wideband. Although the three chip design methods are relatively mature, there still exist some technical difficulties, and none of them have achieved absolute advantage or extensive application. Through the researches on the related technologies and chip design examples, a comparative analysis was made on the three ultra wideband chip design methods in terms of system complexity, peak to average power ratio, overall system power consumption, frequency selective fading resistance, carrier synchronization, symbol synchronization, and spreading gain. The conclusions may provide some useful reference for the selection of ultra wideband chip design methods in different application scenarios.

Grey prediction based link going down trigger algorithm

Bo-wen KONG Ling YUAN Xu-bin ZENG

2011, 31(07): 1976-1979. DOI: 10.3724/SP.J.1087.2011.01976

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Effective and timely Link Going Down (LGD) trigger mechanisms are critical to handover performance. Firstly, this paper introduced IEEE 802.21 MIH standard, and the required handover time was estimated using the information service provided by Media Independent Handover (MIH). Then, a LGD trigger mechanism based on grey prediction was proposed. It established grey prediction model by the required handover time, and the trigger time can be dynamically determined by the predictive Received Signal Strength (RSS) of mobile terminal. Furthermore, in order to reduce the prediction costs, a grey prediction modeling method based on signal decay detection was proposed. The simulation results show that this algorithm achieves the goal of effective and timely LGD trigger, and can reduce unnecessary prediction costs and avoid the waste of terminal resources.

Design and implementation of a solution to multilayer NAT traversal in P2P applications

Ze-yang LIU Wu-ping XU

2011, 31(07): 1980-1983.

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In this paper, all kinds of multilayer Network Address Translation (NAT) penetrate models were analyzed. The problem existing in multilayer NAT traversal was discussed. To solve this problem, the idea of selecting a suitable node as super node based on network environment and designating appropriate super node for the two nodes which need to communicate in order to help communication between them was put forward. The dynamic selection rules of super node were designed. The conversion from P2P topological structure to topological table was completed. The NAT penetrates of P2P systems arbitrary levels were realized by node topological table and the experiment verified the feasibility of the solution to multilayer NAT penetrate given in this paper.

QoS-aware service dynamic real-time composition algorithm for SOA-based critical systems

Yi ZHANG Wan-dong CAI

2011, 31(07): 1984-1987. DOI: 10.3724/SP.J.1087.2011.01984

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SOA-based distributed and embedded safety & mission system (DESMCS) executes in open environments which have different dependability requirements. This paper presents a model for QoS-aware inline service composition in SOA-based DESMCS. QoS-aware service composition is a key requirement in SOA-based DESMCS since it enables fulfilling complex user requirements while meeting strict QoS constraints. The improved heuristic search algorithm solved the NP-hard challenging issue which is the selection of the best set of services to meet global QoS constraints imposed by the user. This paper also presents a set of experiments conducted to evaluate the efficiency of our algorithm, which shows its timeliness and optimality.

Collaborative design system of automatic weapon based on basic class module template

Li LOU Cheng XU Yong-juan WANG Fei-meng ZHANG

2011, 31(07): 1988-1991. DOI: 10.3724/SP.J.1087.2011.01988

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The functional model and architecture of collaborative design system for automatic weapon were analyzed. A unified module template instance and its information access relationship model of automatic weapon were presented to achieve practical collaborative design. The proposed system includes configuration management, model-lib management, integrated service model, hierarchical collaborative design process model and cooperative behavior prediction and analysis module which assist collaborative design of modularized products. Combining the API functions development technology of CAD software and the supports of Web services technology with common language interface, the system has been implemented in reliable distributed interactive supporting environment.

Data fusion based on evidence theory by preprocessing in wireless sensor network

Xiu-li REN Yang TIAN

2011, 31(07): 1992-1994. DOI: 10.3724/SP.J.1087.2011.01992

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The recognition results of the same target by different sensors are often contradictory in wireless sensor networks. The use of data fusion based on DempsteShafer (D-S) evidence theory could solve this problem. However, when using D-S evidence combination formula to compute，with the increase of the target identity, the computation will be growing rapidly. The processing ability of sensor nodes is limited and the data of decision in sensor networks are redundant, thus，a way was proposed to reduce the number of target identity by preprocessing and to reduce the computation; and it could rule out the data with errors through greater consistency test; therefore，it makes decision results more accurate.

Display and enhancement of spectrogram based on field programmable gate array

Zhong-xing TAO Dong PEI Quan-zhou WANG Hong-wu YANG Hui-xin PEI

2011, 31(07): 1995-1997. DOI: 10.3724/SP.J.1087.2011.01995

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In the current research and design of spectrogram based on Field Programmable Gate Array (FPGA), the direct indication of the spectrogram is not able to reflect the detail variation of spectrum. To solve this problem, a method for the display and enhancement of spectrogram based on FPGA was proposed in this paper. With nonlinear transformation, the high-resolution gray image was compressed to low gray-resolution image, so the detail variation of spectrum would be better reflected. Meanwhile，human vision is less sensitive to the difference between gray-scale pixels than that of colors, so with pseudo-color processing of the gray images, the results are displayed through Video Graphics Array (VGA). The experimental results show that more detail variation of spectrum can be obtained by the method.

New divisional fire strategy of RoboCup rescue simulation

Yun-biao WU Yi-min YANG

2011, 31(07): 1998-2000. DOI: 10.3724/SP.J.1087.2011.01998

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In the fire strategy of RoboCup rescue simulation, controlling the spread of fire plays an important role in rescue effect. Most teams use single-objective selection method based on various indicators of the single building. It is difficult for this method to control the fire effectively when more buildings are in fire or the fire spreads quickly. This paper proposed a new partitioning method based on density cluster. In this method, all the buildings were clustered and seperated into different regions according to the fire spread speed, the target region and buildings extinguishing the fire were selected by the weight considering both the fire spread speed and the building attribute, thus the fire could be controlled even completely extinguished. Finally, the validity of this method has been confirmed through simulation test and competition.

Design and application of migration information system based on World Wind

Ren-gui JIANG Jian-cang XIE Jian-xun LI Ming-xiang YANG

2011, 31(07): 2001-2003. DOI: 10.3724/SP.J.1087.2011.02001

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To solve the problems of huge storage, difficult management, poor display of data and decision support, a Migration Information System (MIS) based on three-dimension GIS named World Wind was designed and developed. Its system architecture and functional modules were designed, MIS was developed based on World Wind Java SDK, Digital Elevation Mode (DEM) and image data were divided, stored, organized and scheduled, based on which integration and application of migration information were accomplished. A case study shows that the system has good extensibility and 3D effect.

Design and realization of branch prediction for embedded microprocessor

Hai-min CHEN Zheng LI Rui-jiao WANG

2011, 31(07): 2004-2007. DOI: 10.3724/SP.J.1087.2011.02004

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Concerning the specific application environment of embedded microprocessor, the branch prediction technology was researched in this paper, and a new scheme of branch prediction was proposed. Compatible with cache design, jump direction and destination address of branch prediction happened on extended instruction bus. The unexecuted instruction and address pointer were saved for possible recovery after misprediction, which reduced misprediction penalty, simultaneously guaranteed the instruction flow to execute correctly. The study shows this scheme is of little hardware spending, high prediction efficiency and low misprediction penalty.

Design and implementation of U disk virus isolator with hi-speed

Yi ZHANG Xiao-quan YANG

2011, 31(07): 2008-2010. DOI: 10.3724/SP.J.1087.2011.02008

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The popularization of U disk makes virus from U disk spread fast. In order to protect the safety of information system, the authors designed a U disk virus isolator with three functions, firstly isolating Autorun virus from U disk, secondly preventing the PCs data from stealing by U disk, and thirdly preventing the PCs virus from spreading to U disk. The isolator can quickly capture all the data between the U disk and the PC, then the Micro Controller Unit (MCU) of the isolator analyzed, filtered and audited the data transport between U disk and computer to implement those three functions described above. Through actual measuring, it is found that this design can implement those three functions successfully.

Discrete variable structure control based on ideal reaching law with dynamic disturbance compensator

Yun-long LIU Cun-chen GAO Lin ZHAO Xiao LIANG

2011, 31(07): 2011-2014. DOI: 10.3724/SP.J.1087.2011.02011

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Synthesis problem of Variable Structure Control (VSC) for mismatched uncertain discrete-time systems with internal parameter perturbation and external disturbance was researched. The ideal reaching law with dynamic disturbance compensator of mismatched uncertain discretetime systems was designed to eliminate the restriction of the system uncertainty bounded and the satisfaction of matching conditions compared with VSC by conventional reaching law. Discrete variable structure controller was designed by applying this type of reaching law, which not only guaranteed the system to reach the switching surface in finite time and decreased the system chattering effectively, but also reduced the region of the switching belt and enhanced the dynamic quality of the control system. The simulation results illustrate the feasibility and validity of the proposed approach.

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