Journal of Computer Applications

Survey on techniques of SoC hardware/software co-design

XIONG Guang-ze;ZHAN Jin-yu

2006, 26(4): 757-760.

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With the increasing development of the technology in microelectronics and computer science, embedded applications are widely used in many fields, such as consumer electronics, intelligent electronic household appliances, and communication equipments. The present status of embedded system was introduced,the trend in the future was analysed,the deficiency of the traditional design methods was presented.The hardware/software codesign methodology of SoC embedded systems was proposed,the supporting techniques were given.

Comparison and analysis of major embedded real-time operating systems

2006, 26(4): 761-764.

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With the foundation of real-time, fault tolerant, standard compatibility,a standard for embedded real-time OS was suggested, which included embedded OS architecture, supported hardware, schedule management, memory management, interprocess communication, timer performance, network support, file system, driver development and debug and so on. Also a detailed analysis and comparison for major embedded real-time operating systems was given,and it can be a good guide to select the best embedded real-time OS for the application situation.

PCI bridge-based dual CPUs communication technology

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2006, 26(4): 768-770.

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Most of the PCI bus cards are implemented based on PCI bus bridge and special microprocessor chip to fulfill specific requirements. For advanced application with PCI bus cards,embedded CPU and OS are used. Environment characteristics of dual CPUs on PCI bridge were researched, and key points about communication design were summarized. The configuration and usage of typical PCI bridge were studied,and an example of security network interface card based on our research was introduced.

Design of advanced RTU in dispatching automation of electric power system

吴仲光;张丛耀;邓晴源

2006, 26(4): 771-773.

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The design and implementation of a new type Remote Terminal Unit(RTU) based on 32-bit ARM CPU LPC2214 in dispatching automation of electric power system were introduced. The shortcomings of the old RTU were analyzed and some improvements on software and hardware were put forward.Full advantages of integrated function blocks of LPC2214 were taken, and InApplication Programming(IAP) technology and Fourier algorithm were used to develop new type RTU. The new type RTU has simple peripheral circuits, high reliability, excellent expansibility and notably improved function. It is easy to be used and maintained, and easy to use the new type RTU to buildup large scale monitoring network.

Realization technology of EMCS and application in wastewater treatment

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2006, 26(4): 774-775.

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The related implementing technology of embedded monitoring and control system(EMCS) was presented,and the functional modules was designed with the analysis of its demand of reconfiguration. The feasibility of the EMCS was illustrated with the Windows CE.NET based on system for wastewater disposal of paper making with secondary fiber.

New perception and autonomous behavior modeling approach for Avatar

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2006, 26(4): 776-779.

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Based on the research of 3D facial model reconstruction and intelligent virtual entrainment, a new perception and autonomous behavior modeling approach for Avatar was proposed. In the new method, the Avatar was considered as an Agent,which could recognize 3D objects in the environment and calculate the direction of the moving objects by using the Avatars perception sensor. Avatar walk behavior was simulated by skeleton model and denoted by seven motion sequences. Experiment results show that the new approach is more efficiency.

Electric flux-based 3D model retrieval algorithm

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2006, 26(4): 780-783.

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The retrieval methods and application of the content-based 3D model were investigated.A new 3D models electric flux descriptor was proposed on the basis of the electrical flux theory of electrostatics.The 3D model was supposed as charged body,then electrical flux was gotten by placing some testing concentric spheres around it. The electric flux descriptor is invariant to rigid transformations. Experiments show that it is a robust and effective method.

Research on initialization of image segmentation with FCM algorithm

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2006, 26(4): 784-786.

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Fuzzy C-Means(FCM) algorithm is one of the most popular methods of clustering analysis. However, the traditional FCM algorithm does not work well because its initial clustering central collection is the stochastic selection. An efficient PFCM algorithm was proposed. Based on the solving multinomial root, the PFCM algorithm solved question of initial clustering central collection of data set. The experiment result demonstrates its effectiveness.

Algorithm of iris identification based on orthogonal Legendre moments

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2006, 26(4): 787-789.

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Orthogonal Legendre moments were utilized to achieve characteristics extract from an iris image. Each feature vector, based on this algorithm, included the grey value and coordinate of each pixel in the image. Compared with other algorithms based on moments, this algorithm not only favors the robustness, but also preserves the 2D information of the image. The experiment results indicate that the algorithm has good effectiveness and rationality.

Ear recognition based on improved NMFSC

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2006, 26(4): 790-792.

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Based on ear recognition, an improved NMFSC(Nonnegative Matrix Factorization with Sparseness Constraints) method was proposed by imposing an additional constraint on the objective function of NMFSC, which could capture the semantic relations of coefficient matrix as orthogonal as possible. The interated rules to solve the objective function with the constraint were presented, and its convergence was proved. The suitable weights were chosen for subregion based on classcluster rule, which could get the optimal mapping overall similarity from subregion similarity. The experiment results show that the proposed method can obtain better performance.

Heterogeneity distributed fractal image compression algorithm based on genetic algorithm

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2006, 26(4): 793-796.

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An effective approach of the fractal binary image compression was presented based on genetic algorithm and IFS(Iterated Function System). And then, a heterogeneity distributed version of the binary fractal image compression algorithm was implemented according to the existent distributed or parallel framework. In addition, designed scheme of a sophisticated distributed model was elaborated. Both the oretical analysis and experiment results show that the proposed algorithm has tremendous ability in searching best solutions, and can find out one of the most approximate result of IFS whose decoding image is quite similar with original one, and also has a higher compression ratio with high quality image.

Research on adaptive block matching algorithm

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2006, 26(4): 797-798.

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In order to extract motion vector to realize video retrieval efficiently,the existing problems and characters of video information were analyzed. Then a global motion feature extraction scheme based on adaptive block matching fast searching algorithm was put forward. Experiments show that the algorithm can obtain almost the same PSNR as the full search algorithm at very low computation cost.

QoS mapping based on MPEG-4 video streams

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2006, 26(4): 799-802.

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The mapping of Quality of Service(QoS) for MPEG-4 video streams was presented based on XVID MPEG-4 codec and RTP(Real-time Transport Protocal). First,the characteristics of MPEG-4 video streams, codec and layered management of QoS was analyzed. Then,a logical structure of QoS management based on RTP and QoS parameters of MPEG-4 video streams in application layer and system layer were presented. The QoS mapping algorithm and calculating formulas from application layer to system layer were put forward. Finally, results of simulation experiments reveal that the proposed mapping algorithms and formulas can meet QoS of MPEG-4 video streams.

Optimum algorithm of S-boxes based on fast convergence speed genetic algorithm

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2006, 26(4): 803-805.

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The optimization of S-boxes based on genetic algorithm was discussed, and the heuristic mutation strategy was used in this algorithm. Results of the experiments indicate that the mutation operation has high searching efficiency and fast convergence speed. Meanwhile, the selection strategy of preserving the best individuals can reduce the calculation time greatly. Based on the method, an effective genetic algorithm for 6×6 S-boxes was provided and a number of S-boxes with high nonlinearity and low difference uniformity were obtained.

Multiple data packet analysis of network intrusion detection system based on multilayer forward neural network

YanTao Zhou;;;

2006, 26(4): 806-808.

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A new network intrusion detection model was proposed.Based on the model,the currently data packet was integraed with historical data packet to process a protocol analysis,then the data packet that correlated with possiblely intrusion affair could be found out.The multilayer forward neural network was used to process a regression analysis to such data packets and got the results of intrusion detection.With the new model based on multiple data packet,the missed rate of traditional network intrusion detection system was decreased.

VSS scheme based on bilinear pair

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2006, 26(4): 809-811.

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A Verified Secret Share（VSS） scheme based on bilinear pair was proposed,and a INDCCA2 proof to this scheme was given. The efficiency of this scheme is higher than the schemes based on Eclipse Curve Discrete Logarithm Problem(ECDLP), and the required band is narrower than theirs so it works well in rigorous environment. Then an analysis of the choice of the eclipse curve was given in order to get a higher security level that fit for this scheme.

Robust digital video watermarking algorithm against collusion attack

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2006, 26(4): 812-814.

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To improve the collusion attack of the video watermark, video content features were studied in domain of discrete cosine transform, the algorithm in which both watermark information and its position information depend on content of embedded point was presented. Finally, experiment was performed to detect robustness of the algorithm.The result demonstrats that the algorithm is robust to collusion attack.

High capacity blind information hiding algorithm based on DCT

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2006, 26(4): 815-817.

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The AC coefficients of an image's Discrete Cosine Transform(DCT) are best approximated by Laplacian distribution model. Based on this model,the blind information hiding algorithm was proposed. Using a novel data embedding rule, this algorithm adjusted coefficients of DCT,whose absolute value is relative smaller than others. Positive numbers were used to denote one and negative numbers were used to represent zero respectively. Furthermore, the original image was not needed to extract secret data. The experiment results show that the algorithm has high capacity attribute, which is suitable for applications of secret communication.

Secure access control protocol for multi-source IP multicast

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2006, 26(4): 818-819.

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The current secure access control techniques in IP multicast just implemented the access control to multicast receivers. A novel secure access control protocol MMAC (Multi-source Multicast Access Control) was proposed, which was widely applied to multi-source IP multicast. The secure access control to multicast participants and un-trusted routers was implemented by introducing special managing host and managing channel. The validity and security of MMAC protocol was analyzed at last.

Novel unsupervised anomaly detection based on robust principal component classifier

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2006, 26(4): 820-823.

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Intrusion Detection System(IDS) needs a mass of labeled data in the process of training, which hampers the application and popularity of traditional IDS. Classical principal component analysis is highly sensitive to outliers in training data, and leads to the poor classification accuracy. A novel scheme based on robust principle component classifier was proposed, which obtained principal components that were not influenced much by outliers. An anomaly detection model was constructed from the distance in the principal component space and the reconstruction error of training data. The experiments show that the approach can detect unknown intrusions effectively, and has a good performance in detection rate and false positive rate.

Research on performance testing of IKE protocol

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2006, 26(4): 824-826.

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A black box testing method aiming at IKE（Internet Key Exchange） protocol performance was proposed,which was based on the selfdeveloped platform of protocol integrated test system. Flexible test suite was designed according to characteristics of IKE,and the IKE performance testing was done on one actual host,all kinds of parameters' impact on IKE performance was analyzed. This test method is applicable to IKE tests in different devices.

Research on digital image encryption method based on hybrid chaotic system

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2006, 26(4): 827-829.

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The security of image encryption methods was analyzed, and improved method of image encryption named changing parameters and chaotic complex system of double Logistic-maps was presented, which consisted of two sets of Logistic-maps. In this system, the two Logistic-maps can control the parameter μof each other and thus produce two chaotic sequences. Then one of the sequences is used to disturb the image matrix, while the other sequence to encrypt the image. The computer simulation results proved that the method is easy, feasible, and effective in encryption. Besides, this method is also well against attack and noises. Key words: Chaos； Logistic-map； Image encryption； Information security

Adaptive digital watermarking algorithm based on energy analysis of wavelet coefficients block

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2006, 26(4): 830-832.

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To enhance the robustness of watermark, an improved digital watermarking algorithm based on wavelet transform was proposed. The third level detail sub-images decomposed the original image using three levels DWT(Discrete Wavelet Transform) were divided into non-overlap blocks. Then the blocks, which were more adaptable to embed watermark, were selected by block energy analysis. At the end, combining with the properties of human visual system, the watermark was adaptively embedded into the largest coefficients which belonged to the selected blocks. Theoretical analysis and experiment results show that the watermark generated with the proposed algorithm is imperceptible and more robust.

Design of a reputation model for P2P network security

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2006, 26(4): 833-835.

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In order to ensure network secure and reliable and provide better and more qualified service,a reputation model was proposed to isolate bad peer. The mathematical model and algorithm to resolve reputation were given,and the factors which influences reputation were introduced.Simulating and analysis shows that the reputation model can isolate bad peer effectively

Research of component composition technology based on software architecture connector

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2006, 26(4): 836-839.

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Component is designed for reuse and composition, but the problems concerning compositional mismatches often happen in the process of component composition. Analyzing from an architectural point of view, sticking points of the problems can be found. Based on the research of the software architecture and the component composition technology,the component composition technology based on software architecture connector was put forward, and an example was introduced.

Research of lightweight Web application based on Spring MVC and iBATIS frameworks

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2006, 26(4): 840-843.

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To describe the design and development of Java-based Web application systems under the actural business environment of large or small scale, the frameworks of Web application systems, the open frameworks Spring and iBATIS and the related IoC mechanism was discussed. Then a solution for light weight Web application systems based on Spring MVC and iBATIS frameworks were proposed. The JSP and JSTL technologies were also introduced into this solution. The good performance of application systems in the test and running phases manifests a remarkable improvement of the proposed system framework in security, stability and robustness issues.

Research on automatic generating test case method based on UML activity diagram

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2006, 26(4): 844-846.

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Based on UML activity diagram,the system test method was described.Aiming at activity diagram semi-formal speciality，the activity diagram formal specification and the definition of test coverage rules were given. Then the permutation of intercurrent activity was analyzed. The interactive method between tester and computer enhanced the restriction of arithmetic on generating test scenario, reduced the number of testing scenario, promoted the feasibility of automatic generating test case. At last,how to get test case from test scenario was discussed. Thereby automatic generating test case from UML activity diagram became systemic, feasible and effective.

Design and implementation of supporting framework for collaborative work in distributed software development

JingHua Liu;

2006, 26(4): 847-849.

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In order to effectively support distributed development and make software collaborative development environment more effective and comfortable to use,collaborative theory and application tool were integrated with formal description.This practice effectively improves the intelligence and scalability of the environment, along with the quality of software and the productivity of the development.

Research and realization on load balancing strategy in EJB cluster system

Fang wei;;

2006, 26(4): 850-852.

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The design methods and load balancing algorithm of EJB clustering system was analyzed,and a new approach based on the BP neural networks was presented to solve the load balancing algorithm problem. How to design the BP Neural Network model was researched.The example shows that the system based on this algorithm is proved to reach better effects.

Design and implementation of three-tiered application server with business logic reconstruction

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2006, 26(4): 853-856.

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Networking applications can be described as a set of form flows, event flows and data flows. Based on these three kinds of flows,a business logicreconfigured framework of three-tiered application servers was proposed, and an ICETIP (Information-Centered Enterprise Transaction-Integrated Processing System) application server was developed,which is a transaction processing system with the ability of reconstructing and reconfiguring networking applications. Then the structure and implementation of the ICETIP application server were presented, including a client connecting pool and a database connecting pool and communicating mechanisms between clients and the application server. ICETIP is a new mode of developing and deploying networking applications,which can be used to build different kinds of applications without any further programming.

Research on shop scheduling optimization based on genetic and tabu search hybrid algorithm

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2006, 26(4): 857-860.

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In order to avoid premature convergence and to balance the exploration and exploitation abilities of simple GA,a hybrid algorithm was proposed to solve dynamic scheduling problem in flexible production environment. It is using GA excellent whole search ability and self-adaptive merit of Tabu Search(TS), and the convergence of research was improved. It is capable of generating alternative schedule after uncertain disturbance takes place on a job shop. After using crossover and mutation operations, a best or second best scheduling plan can be found. The result of the test shows that the method is feasible and efficient.

Research on data mining method based on attribute-oriented generalization and information gain

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2006, 26(4): 861-863.

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According to the characteristics of attribute-oriented generalization method and knowledge granule successive based on rough set,after organically combining these two method, the classification rules could be rapidly mined in database. The method of attribute-oriented generalization was firstly used to generalize the dada, and then the technology of information gain was utilized to find the dependency relation of data. The algorithm was applied in the classical simulation example and the result is rational and reliable.

Improved CEBARKNC on decision table reduction

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2006, 26(4): 864-866.

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CEBARKNC(Conditional EntropyBased Algorithm for Reduction of Knowledge without Computing Core) algorithm is based on conditional information entropy for reduction of decision table, but the algorithm is incomplete for some decision table.After analyzing the CEBARKNC algorithm,the reason for incomplete reduction was found,the construction of the heuristic information was discussed,and an improved algorithm which combined the algebra of the rough set theory and the conditional information entropy was put forward. The conditional information entropy was the heuristic information of the attribute reduction.

Hierarchical analysis for discovering subject field of multidimensional data model

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2006, 26(4): 867-869.

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To meet an organization's decision requirements and strategy goals, the subject field of multidimensional data model could be discovered by hierarchical analysis in the process of implementing Goal-Question-Metric(GQM). The attributes associated with a subject could be found by an mining algorithm in a database. The result has guide to show the multidimensional exhibition structure in data warehouse scientifically.

Design and realization of dynamic rectangle-based clustering approach

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2006, 26(4): 870-871.

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A dynamic rectangle-based clustering approach(DRCA) was presented.The number of data that needed to be examined for clustering was reduced,and in each procedure of clustering,the position comparison between numbers was used without any distance comparison,which made DRCA had the nearly linear time complexity with the size of dataset. The experiment results show that the DRCA is correct and efficient.

Distributed association rules mining algorithm by sampling and meta-learning

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2006, 26(4): 872-874.

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A new distributed association rule mining algorithm of DASM was presented. It adopted the ideas of dynamic itemset counting and sampling, and produced frequent itemsets by meta-learning method. Different sites that applied DASM needn't share the same memory. To assure the completeness of the results, the concept of similar degree was introduced. Theory analysis and experiments on the datasets generated using the generator from the IBM Almaden Quest research group show that DASM has better performance and less communication loads. DASM is applicable to those applications where the efficiency could be more important than accuracy results.performance and less communication loads. DASM is applicable to those applications where the efficiency could be more important than accuracy results.

Documents clustering based on frequent term sets

2006, 26(4): 875-877.

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Novel method of frequent term sets-based text clustering was presented. For the pretreated documents,such frequent sets could be efficiently discovered by using the Apriori method,which subset was used for documents clustering according to frequent terms' correlation. This method allows us to reduce drastically the dimensionality of the term sets and provides an understandable description of the discovered clusters by their frequent terms sets.

Approximately duplicated records examining method and its application in ETL of data warehouse

Yong Zhang;;

2006, 26(4): 880-882.

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Examining and eliminating approximately duplicated records is one of main problems needed to solve for data cleaning and improving data quality. The position-coding technology to ETL of data warehouse was introduced,a novel examining algorithm named Position-Coding Method(PCM) of approximately duplicated records was presented.The algorithm was applied to Chinese character set, as well as Western character set. Experiment comparison with the previous work indicates that the method is effective.

Text-dependent speaker recognition method using MFCC and LPCC features

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2006, 26(4): 883-885.

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In the process of feature extraction of a text-dependent speaker recognition system,the difference of Mel Frequency Cepstrum Coefficient(MFCC) and Linear Prediction Cepstrum Coefficient(LPCC) was chosen to be the speech characteristic parameters,and in the process of speech modeling,a variance was added to the code word of Vector Qantization(VQ) and got continuous vector quantization,then compared it with Dynamic Time Warping(DTW) method and VQ method in text-dependent speaker recognition experiment.The results of identification show that the recognition efficiency is proved without any obvious increasing of responds time.

Immunity clone algorithm with particle swarm optimization

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2006, 26(4): 886-887.

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To use the clonal selection mechanism of the immune system and combine with the evolution equation of particle swarm optimization,an advanced algorithm was introduced to optimize functions. The advantages are via immunity operation to maintain diversity of the antibodies, and the speed of convergent are improved by using evolution equation. The simulation results show that the algorithm can converge to the global optimum at quicker rate in a given range.

New time series forecasting approach for complex systems based on series decomposing

HAN Xue-mei;;

2006, 26(4): 888-890.

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Time series are often produced in complex systems which are controlled both by macroscopic level and microscopic level laws, with long memory effect and short-term irregularly fluctuations coexisting in the same series. Traditional analysis and forecasting methods didn't distinguish these multi-level influences and always made a single model for predication, which had to introduce a lot of parameters to describe the characteristics of complex systems and result in the loss of efficiency and accuracy. However,we decomposed time series into several ones with different smoothness, all the sub-time series were respectively modeled and predicated with multi-scale sampling. Then the forecasting results of sub-time series were composed to get the result of the original time series. The experiment results on the stock forecasting show that the method is efficient, even for the time series with large fluctuations.

Model representation and model composite based on Agent

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2006, 26(4): 891-894.

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In light of the analysis of the traditional methods of model representation and model composite, a novel theory of model representation and model composite based on Agent technology was proposed. Through the mechanisms of knowledge and intelligence, this novel method can clearly separate the model from data and object, and provide the abilities of adaptability and learning for models. And then, the complex and illegible composite of model is transformed into a problem of negotiation and cooperation of multi-agent system, so these methods bring forward a novel solution for model based and decision support system.

Locally adaptive nonlinear dimensionality reduction

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2006, 26(4): 895-897.

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Popular nonlinear dimensionality reduction algorithms, such as SIE and Isomap suffer a difficulty in common: global neighborhood parameters often fail in tackling data sets with high variation in local manifold. To improve the availability of nonlinear dimensionality reduction algorithms in the field of machine learning, an adaptive neighbors selection scheme based on locally principal direction reconstruction was proposed.The method involves two main computation steps. First, it selects an appropriate neighborhood set for each data points such that all neighbors in a neighborhood set form a d-dimensionality linear subspace approximatively and computes locally principal directions for each neighborhood set respectively. Secondly, it fits each neighbor by means of locally principal directions of corresponding neighborhood set and deletes the neighbors whose fitting error exceed a predefined threshold. The simulation show that the method can deal with data set with high variation in local manifold effectively. Moreover, comparing with other adaptive neighbors selection strategy,this method can circumvent false connectivity introduced by noise or high local curvature.

Contracted neural network algorithm of credit rating evaluation

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2006, 26(4): 898-900.

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Aiming at the complexity of adjusting its parameters from the complexity of the structure of classical neural network, the nonlinear of credit rating evaluation was analyzed, and the structure of constructed neural network was advanced. Then, the equipollence of them was proved if all crunodes functions are linear and all inner crunodes function pass origin, and the constructed neural network algorithm was designed. The case indicates the contracted neural network algorithm get to a preferable precision.

Research on QoS multicast routing protocols in MANET

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2006, 26(4): 901-904.

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A logical Hypercube-based virtual dynamic backbone model for QoS-aware multicast communication was proposed after analyzing and comparing several QoS routing protocols in Mobile Ad hoc NETwork(MANET).The model has the properties of high availability and good load balancing, which are the new requirements to guarantee QoS in MANET. A novel logical location-based self routing algorithm was designed based on the model. Simulations show good performance of the proposed algorithm, such as small delay, small delay jitter and strong fault tolerance.

Research of link state updating mechanism in QoS-based routing

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2006, 26(4): 905-907.

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Aiming at reducing the huge link state updating communication overhead in QOSPF(QoS-extended OSPF) due to frequent flooding,two new link state updating methods was put forward:FBLT(Flooding Based Link State Updating Tree) and IFBLT(Improved FBLT), which could significantly reduce the communication overhead. The two methods were created by using the acknowledgement mechanism in LSA(Link State Advertisement). The effectiveness of the two methods was also proved through theoretic analysis and simulation with NS-2.

Localized multi-path QoS routing algorithm for multi-priority traffic flows

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2006, 26(4): 908-910.

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Global QoS routing algorithms require precise global network QoS states. Due to non-negligible propagation delay and dynamic processing overhead, it is difficult for nodes to maintain the precise global QoS information.A localized QoS routing scheme was proposed in the case when there are flows of different priorities and nodes only know partial state information of the network. Simulation results demonstrated that the algorithms can achieve good performances.

Design and implementation of preprocessor for spatial fine granularity scalable coding

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2006, 26(4): 911-913.

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To apply Spatial Fine Granularity Scalable Coding(S-FGS) efficiently, a design and implementation of preprocessor was proposed. This scheme used small RAM to store frame data. Moreover, parallel and pipelined data could be effectively applicable to this scheme. The analysis based on the simulation of the preprocessor shows that the scheme can meet the functional and real-time requirements of S-FGS.

Routing algorithm for sensor networks based on grid and trajectory

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2006, 26(4): 914-917.

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With the analysis of the characteristic of high density of nodes deployed in wireless sensor network, a new routing algorithm was proposed based on combination of grid structure and trajectory-based forwarding algorithm. The new algorithm firstly constructed the suitable grid, then controled the number of working node in each cell to be only one, and the other nodes will stop working until the working node lose its energy, finally working nodes forward data with TBF. Theoretic analysis and simulation results show that the new algorithm has better performances.

Improvement of Chord routing algorithm

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2006, 26(4): 918-921.

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Routing is essential in P2P applications, and it is very important to locate the nodes that contain given data items. Chord is a successful routing algorithm, but the routing table in Chord has a terrible problem of information redundancy. To address this problem, an improved Chord algorithm was proposed which inherited the advantages of Chord, such as simplicity, efficiency, reliability, load balance and low cost. The routing table was improved to gain more useful information and get higher efficiency.

Detectionbased traversal solution for connection between symmetric NAT and portrestricted NAT

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2006, 26(4): 922-925.

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To resolve the problem of NAT traversal in the applications of audio and video based on P2P technology, STUN as a IETF standard was proposed. But it can't traverse the Symmetric NAT. A new solution to resolve the problem was presented by detection with the analysis of Symmetric NAT and the its deploy. Some tests were taken in real situations and the results reached the goal.

Scalability issues of distributed virtual environment

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2006, 26(4): 926-928.

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Two kinds of technologies about the scalability of distributed virtual environment were introduced. One tries to improve system's scalability by paralleling hardware equipments. The example is multi-server parallel partition technology. It can support a large-scale system but with high cost. The other tries to extend DVE system's scale by reducing network traffic, including AOI technology,dead-reckoning algorithm and multicast technology. With the reducing of network load,DVE system can contain more clients, which improves system scalability. As a special refine technology,a combined technology of AOI and multicast was also discussed. With all these techniques discussed in the paper, a system designer can easily construct a large-scale DVE system, which can contain hundreds and thousands users.

Fast approach to inferring loss performance

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2006, 26(4): 929-931.

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Maximum likelihood estimates were often used in the network tomography to identify the loss rate. The time spent on the estimation increased sharply with the size of the network. To overcome the problems caused by MLE, a fast and simple approach was proposed to estimate loss rates. Compared with the previous methods, the proposed one only needed simple arithmetic calculation to determine loss rates, which saved more time than the MLE, and the time spent on the inference do not increased sharply with the size of the network. Through comparison and simulation, it is obtained that the loss inferences match the true results perfectly, and correctly show the loss trend. So the proposed method is very promising in the real network.

Design and implementation of a cluster-based multihop routing protocol for wireless sensor networks

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2006, 26(4): 932-934.

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Basing on cluster-based routing algorithm,a Cluster-based Multihop Routing(CMR) protocol was put forward combining the design of multilhop routing, the design of this protocol and the work process of cluster organization algorithm and routing algorithm of adjacent clusters were analyzed and discussed, which includes the election of cluster head/cluster building,rebuilding of cluster/self-healing mechanism and building and maintenance of routings. At last,the implementation and the test result of this protocol was figures out.

QoS-considered services discovery

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2006, 26(4): 935-937.

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The service discovery is the core technique of service framework, and the key part of service brokers that link service providers and service consumers in heterogeneous distributed systems. A QoS-Concerned services Discovery(QSCD) was proposed,which complemented the existing service discovery. QSCD is a consumer-oriented mechanism of service discovery, which builds at the side of service consumer and is only used by consumer himself. It stores information related to the services invoked by the consumer and considers consumer's requirement for QoS. Furthermore Services Information Description Document(SIDD), corresponding schema and APIs were presented. In addition,service reservation and service dommunity was put forward to extend this mechanism. As a result, it can speed up the discovery of services.

Research of IPv6 neighbor discovery protocol security mechanism

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2006, 26(4): 938-941.

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Based on the analysis of principle and security mechanism on IPv6 NDP(Neighbor Discovery Protocol), a summary of its security threats including redirect and denial of service attacks was given. The current mechanisms used by SEND(Secure Neighbor Discovery) to secure the NDP relies almost solely on computationally expensive public key cryptography, which might be a problem on resourceconstrained devices. Accordingly, an alternative to the current specification of SEND which leverage on the required link layer security to secure NDP was proposed. This technique is based on the use of a specific kind of IPv6 addresses, the so-called LL-HBA(Link Layer Hashed Based Addresses), and of link layer address reachability tests. Comparing to the current mechanisms, it does not impose heavy computation on networked nodes. Consequently, it is very practical and deployable.

Minimum interference routing algorithm for multi-protocol label switching network

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2006, 26(4): 942-944.

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An improved Minimum Interference Routing(MIR) algorithm was proposed. It adopted the idea of ProfileBased Routing(PBR) algorithm which used the flowprediction of ingress-egress nodes as routing information. Based on this idea, ingress-egress nodes' weight formula was provided, and how to use the formula in minimum interference routing algorithm was discussed. The improved algorithm can not only meet the practical routing needs better but also heighten the resources usage and throughput of network.

Performance analysis of seven estimate algorithms about the Hurst coefficient

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2006, 26(4): 945-947.

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The factors which affect the performance of estimate algorithms about Hurst coefficient was discussed,including variance, periodic signal and correlation structure. A new serial of correlation structure in a specific scale range was constructed by rearranging FGN（Fractal Gaussian Noise） serial, the scale range was changed continuously and the new serial was estimated. The estimation of each algorithm depended on the correlation structure in a specific scale range, but the structures out of the scale range had no effects on the estimation. For the practical network traffic, the estimations of the algorithms vary according to the correlation structures.

Clustering algorithm based on convergence degree

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2006, 26(4): 948-950.

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Wireless sensor network could be described as an undirected graph. The convergence degree of the node was determined by the ratio of the number of sub-graph's vertexes and number of the edges. The node with the greatest convergence degree was selected as the cluster head to build up the logical structure of the network. The experiment results show that the proposed method yields the lowest overlap of the clusters comparing with the LID algorithm and the MAXD algorithm.

Design of Agent system based on cluster and multicast

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2006, 26(4): 951-954.

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To study the mobile Agents that applied to distributed networked computing system, a kind of architecture of mobile Agent system based on cluster and multicast was presented. The key technologies of design and implementation was introduced in detail. Experiment results show that the proposed architecture has good performance.

Reactive mesh-based multicast routing protocol

Mei Nian;

2006, 26(4): 955-957.

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Reactive Mesh-based Multicast routing Protocol（RMMP） was introduced. In RMMP, the core node was selected distributively and took responsible for constructing and maintaining the mesh when data packets waited to be transmitted in the network. The senders could transmit without joining the mesh structure in RMMP. The RMMP was also independent on unicast routing protocol. By simulation with NS-2, the protocol performance was analyzed and compared with ODMRP. The result manifests that the control overhead and data deliver overhead are reduced due to decreasing flooding control message and redundant path in network. The protocol alleviates the congestion, improves the data delivery efficiency and enhances the network scalability.

Research of hierarchical inter-domain communication based on H.225 .0 Annex G protocol

ChunXiang Hu;;

2006, 26(4): 958-960.

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To solve the inefficient authentication and authorization of inter-domain communication，an improved communication pattern and its communication process between hierarchical AD(Administrative Domain) was proposed based on the Annex G in H.225.0 of H.323 protocol stack。The scheme used the means that it bound parent GK(Gatekeeper) and BE(Border Element) together in an AD to enhance call authentication and management between AD. Compared to other solutions,it can reduce waste of network resource, and it is more adaptive for video communication and more efficient in communication management.

A SNMP-based algorithm for remote network topology discovery

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2006, 26(4): 961-962.

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A kind of SNMP-based method was proposed to discovery large-scale heterogeneous IP network topology，which includes Agent discovery, toplogical data collection and analysis.The main idea in the process of Agent discovery such as construction of packet, elimate redundant data, analyse algorthim and using not-forwarding devicebased data was discussed.A solution was given to the intermittent router nonresponsiveness, prolonged router non-responsiveness and net numbet-based target address.The result of the experiment illustrates that the method can capture amount of topology information efficiently. Unit SNMP with traceroute can improve the integrity of topology discovery obviously.

Based-compactPCI research and implementation of IPSec with paralleled architecture

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2006, 26(4): 963-965.

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Because the traditional architecture of IPSec was deficient in the performance, a paralleled architecture of IPSec based on CompactPCI with more than one computer and a single card was proposed. After analyzing the paralleled architecture of CompactPCI, the encrypting algorithms of multi-cards and load balance of multi-host, a new design of IPsec paralled architecture on CompactPCI was implemented. At last,the performance of transferring data using paralleled architecture of IPSec were introduced and analyzed.

Research on collaborative filtering algorithm based on item's attribute implicit rating

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2006, 26(4): 966-968.

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After analyzing the previous work of recommendation system and algorithm, a recommendation algorithm based on Web daily record was presented which was accurate and efficient. Based on the behavior of customers, a CGA(Customer-Good-Attribute) model was designed which considered synthetically such factors as times, trails, commodities attributes and those distribution in Web pages.The function to the customers' implicit rating of the attributes of commodities was discussed,and a case was given. Then a filter algorithm was put forward based on attributes of goods. An experience result indicated that the algorithm is effective.

Research on efficient triple disk failure tolerance data placement scheme based on parity code

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2006, 26(4): 969-973.

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The data placement scheme based on single-erasure correcting codes can not satisfy the requirement of storage system on reliability. Now there are more and more researches on the data placement scheme based on multierasure correcting codes such as HDD1, HDD2. But these data placement schemes have some disadvantages such as poor redundancy, heavy computing load. A data placement scheme based on triple parity was designed, which can tolerance three disk errors. It adds two parity disks into a RAID5 disk array system, and uses the horizontal parity, diagonal parity and anti-diagonal parity to correct error. The encoding and decoding algorithm of the data placement scheme is simple, the length of parity stripe is equal in triple parity, computing load is light, and easy to implement. In addition, the performance of this scheme in small writes improves obvious comparing with other multi-erasure correcting data placement schemes, for decreasing the logical relationship among triple parity.

Research on building audit-online network modes

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2006, 26(4): 977-979.

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Three novel audit-online network modes which were introduced as central mode,distribute mode and point to point mode were presented according to the analysis on most ministries and commissions,especially on the informatic environment and the data storage methods.Then each mode was introduced in details, including the basic elements, the key problems and the implementation by using the example of CIQ central-mode audit-online network. As a result, the three modes provide an audit network platform for most ministries and commissions quite efficiently.

Implementation of BGP/MPLS VPN in NS-2

Bo Han;;

2006, 26(4): 980-982.

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The principle of BGP/MPLS VPN was researched,and the ways of implementing BGP and MPLS in NS was analyzed respectively.A new solution to implement BGP/MPLS VPN for the environment of NS-2 was presented which is consistent with the RFC standard. At last, it described how to use this solution to simulate this kind of VPN and some testing results, which proved the feasibility of this solution.

Study of library functions recognizing technology in binary translation

Ning Qi;;

2006, 26(4): 983-985.

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A new processor architecture poses significant risk to software developers, hinder the popularization of the new architecture. Binary translation offers solutions for automatically converting executable code to run on new architectures. The library functions recognizing technique in I2A binary translator was introduced. Especially a new approach of library function recognizing problem was given. It is a simple and practical method to recognizing library functions based on the calling conventions of IA-64 architecture and observation of the program instance. It is proved to be effective by the I2A translation system.

Multitask information detection and communication system design

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2006, 26(4): 986-988.

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The information detection and communication are main function of sensor networks.An information detection and communication system which perfectly united multitask operating system with TCP/IP technology and possessed good communication mechanism between multi-processors was designed and implemented by software. The system has the character of simple structure, common hardware,advanced software design and high practicability.An example of the system was given which showed that the system may widely be suitable for the systemrelated design.

Study on technique of high time coherence used in real-time distributed interactive simulation

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2006, 26(4): 989-991.

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In LAN which use PC and Windows operating system, accurate and effective time coherence using the pattern that software cooperate with hardware is one of the keys for real-time distributed interactive simulation system to improve fidelity and decrease cost. A brief time synchronization algorithms in LAN （LTS algorithms） was bring forward,and a new clock was designed based on resource of PC. In LAN, LTS algorithms has better time adjust effect. The new clock is better than the system clock of Windows operating system in performance. At last, a integrated scheme of time coherence was designed,and the purpose to get accurate and effective time coherence and to decrease cost was realized.

New model of IRT item parameter estimation based on neural networks

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2006, 26(4): 992-994.

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A new modeling method based on general regression neural networks(GRNN) of item parameter estimation within IRT（Item Response Theory） was discussed. The methods about how to construct the output pattern of neural networks, and especially the input pattern by using Monte Carlo method were described. Methods about how to improve the learning efficiency and generalization ability have been proposed. Simulation experiments denote that it is feasible to fit the nonlinear relationship of item parameters between CTT（Classical Test Theory） and IRT given any precision. Comparisons of this method to other methods have been done at last, which suggested it somewhat advantageous.

Automatic building of transfer policy in workflow evolution changes

DengPing Wei;

2006, 26(4): 995-997.

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How to transfer a workflow instance from the old workflow specification to the new workflow specification is the most challenging issue in evolution of a workflow model.An workflow process model was proposed with relative workflow instance model and change model.A new transferring policy was also presented. Each transfer statement of task node in old specification confirm appropriate action according to the relations between specification change points and excute path of workflow instance.In addition, an algorithm of automatically building transfer rule of each task node according to the partial ordering of change node was put forward.

Research on Chinese name identification based on Bayes algorithm

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2006, 26(4): 998-1000.

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Based on the regular probability and statistics theories, a method which used Bayes algorithm to identify all Chinese name in sentence was presented. By using Bayes classification algorithm to calculate the probability whether a Chinese character string should be a Chinese name or nonChinese name, all Chinese name in sentence could be identified efficiently. This method has simple formulae and some learning ability, while combining with other technologies, it can get a good result for Chinese name identification.

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