05 September 2008, Volume 34 Issue 17
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Computer Engineering. 2008, 34(17): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2008.17.001This paper proposes Control-Splitted Data Transfer(CSDT), a novel method for processing data transfer requests between client devices of a transparent system. CSDT waives data transfer through the network—only minimum control information is sent through the network during the process. Instead, data transfer through network is replaced by local disk operations on the server, therefore CSDT improves the data transfer speed and relieves corresponding resource. Test results show appropriate support to the feasibility and effectiveness of the CSDT method.
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Computer Engineering. 2008, 34(17): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2008.17.002The influence of domain decomposition on the parallel computation speed of ARPS model is analyzed on the base of some experiments. Results show that the subdomains similar to square possess the biggest acceleration rate and efficiency of parallel whether the optimization lever -o2 is applied to or not. Under the circumstances of optimization lever -o2, parallel speed also relates to decomposition direction. The decomposition along y direction is preferable to that along x direction for improving in parallel efficiency. However, under the circumstances without optimization, parallel speed is almost independent of decomposition direction. Furthermore, experimental results are discussed in the paper from the angles of communications traffic and optimization.
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Computer Engineering. 2008, 34(17): 7-9. https://doi.org/10.3969/j.issn.1000-3428.2008.17.003Most recent immune models and algorithms against malicious codes not only take too much cost in learning and training, but also have shortcomings to some extend. This paper provides a new computer malicious codes immune model. Instead of detecting or recognizing the exact characters of malicious codes, the model gives computer system the self-immune ability against malicious codes by getting rid of the prerequisites for malicious codes to spread and do harm.
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Computer Engineering. 2008, 34(17): 10-11,1. https://doi.org/10.3969/j.issn.1000-3428.2008.17.004Tuplespace is a kind of structural distributed shared memory programming paradigm. In this paradigm, a shared tuplespace is used to carry out generative communication. To improve the flaw of centralized tuplespace, such as performance bottle-neck, single failure, weak scalability, this paper puts forward a mixed distributed tuplespace architecture, presents the distributed computation model based on π-calculus, introduces the syntax and operational semantics of the model, shows some features of system through the barbed bisimulation.
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Computer Engineering. 2008, 34(17): 12-14. https://doi.org/10.3969/j.issn.1000-3428.2008.17.005This paper proposes a Data Assignment Algorithm Based on Peer to Peer for Streaming Media(DA2SMp2p). The algorithm can dynamically adjust the data assignment according to the changes of the network. When a supply peer is invalidated, the algorithm can keep more continuity of streaming media than Minimum Buffering Delay media data Assignment algorithm(MBDAp2p), an optimal media data assignment algorithm(OTSp2p) and Algorithm_1. When no supply peer is invalidated, segment buffering delay of DA2SMp2p is the same as MBDAp2p and smaller than OTSp2p and Algorithm_1 while the minimum buffering delay of a continuous playback for DA2SMp2p, MBDAp2p and OTSp2p algorithms is same. The minimum buffering delay of a continuous playback for Algorithm_1 is the biggest.
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Computer Engineering. 2008, 34(17): 15-17,2. https://doi.org/10.3969/j.issn.1000-3428.2008.17.006This paper presents a product development process simulation model taking account of resource constraint. Resources are assigned to activities based on their roles in controlling information spreading, and such resource assignment algorithm seems to be efficient compared with Cooper’s algorithm. Through this model, detailed information of project development process can be obtained, including project lead time, durations of each task, and the influence of resource binding upon project lead time. This model is useful in assisting project managers to predict, monitor and control product development.
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Computer Engineering. 2008, 34(17): 18-20. https://doi.org/10.3969/j.issn.1000-3428.2008.17.007In order to build a grid identity based grid job monitor system for local site management, the paper presents a grid job monitoring module scheme on the analysis and research of WSRF specification and WS-GRAM implementation mechanism, and also describes the implementation details of each component in the prototype system. The prototype system can integrate with WS-GRAM to monitor job state as user’s grid identity, and can further provide grid authorization service with dynamic information.
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Computer Engineering. 2008, 34(17): 21-22,2. https://doi.org/10.3969/j.issn.1000-3428.2008.17.008A bio-entity name recognition approach using edit distance and multiple postprocessing methods is presented, which expands dictionary via the abbreviation definitions identifying algorithm and improves the recall rate through the edit distance algorithm. The post-processing methods of improving the performance including first-keywords and post-keywords expansion, POS(Part of Speech) expansion, merge of adjacent entity names and the exploitation of the context cues are discussed. Experimental results show that with the above methods even an internal dictionary based system can achieve a fairly good performance.
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Computer Engineering. 2008, 34(17): 23-25. https://doi.org/10.3969/j.issn.1000-3428.2008.17.009A novel pattern recognition algorithm called Kernel Affine Subspace Nearest Points(KASNP) classification is presented. Inspired by the geometrical explanation of Support Vector Machine(SVM) that the optimal separating plane bisects the closest points within two class convex hulls, KASNP algorithm expands the searching areas of the closest points from the convex hulls to their corresponding class affine subspaces in kernel space. The affine subspaces are taken as the rough estimations of the class feature sample distributions, and their closest points are found. The hyperplane to separate the affine subspaces with the maximal margins is constructed, which is the perpendicular bisector of the line segment joining the two closest points. The test experiments compared with the Nearest Neighbor(1-NN) classifier and SVM on the ORL face recognition database show good performance of this algorithm.
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Computer Engineering. 2008, 34(17): 26-27,3. https://doi.org/10.3969/j.issn.1000-3428.2008.17.010For the need of Intelligent Traffic System(ITS) on urban expressway, this paper presents a real-time traffic state estimator. The basic principle is to integrate Extended Kalman Filtering(EKF) with macroscopic hydrodynamic traffic flow models, and to estimate future traffic states in real time based on traffic detectors that fixed on urban expressway. The result of an example shows acceptable applicability and precision of the method, which can provide reference for traffic control and traffic guidance.
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Computer Engineering. 2008, 34(17): 28-30. https://doi.org/10.3969/j.issn.1000-3428.2008.17.011To improve the training speed of Support Vector Machine(SVM) ensemble, this paper proposes a new approach of SVM ensemble using convex-hull algorithm. The approach applies convex-hull algorithm to get from each class the hull vectors and takes these hull vectors as the training dataset for every base-classifier, Bagging method is used to aggregate the base-classifiers. Threshold is set to discard the base-classifiers with weak performance in training the ensemble to further improve the classification accuracy. Experimental results obtained from applying the proposed approach to 3 different datasets indicate that on average it accelerates training by 266% and speeds up classifying by 25%.
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Computer Engineering. 2008, 34(17): 31-33. https://doi.org/10.3969/j.issn.1000-3428.2008.17.012This paper proposes a Traffic-adaptive Hybrid MAC(THMAC) protocol for wireless sensor networks. THMAC combines the advantages of TDMA and CSMA, tracks the situation of traffic and collision through forecasting mechanism, which lets node choice different channel access mode under different load, and efforts to achieve the adaptive mixed of CSMA and TDMA, which reduces the probability of data conflicting while striving to maintain higher channel utilization. Simulation results show that the THMAC can effectively lower the network data conflicting rate, and maintains a higher throughput when the number of contenders changes.
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Computer Engineering. 2008, 34(17): 34-36,6. https://doi.org/10.3969/j.issn.1000-3428.2008.17.013As an embedded GIS backend, embedded spatial database provides the spatial data and attribute data storage, search, query and other functions. Among them, query performance is one of the basic direct factors impact on the operating efficiency of embedded GIS. This paper talks about the classification of the embedded spatial database integrated query algorithms, puts forward and realizes the spatial first serial query algorithm, the attribute first serial query algorithms and the parallel query algorithm. These three query algorithms are tested and compared, and the test results are given.
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Computer Engineering. 2008, 34(17): 37-38,4. https://doi.org/10.3969/j.issn.1000-3428.2008.17.014According to the features of the existed algorithms of 0-1 knapsack problem, a new non-recursive algorithm is formally derived in the paper. From the recursive equations for computing optimal value of 0-1 knapsack problem, by employing the formal derivation technique and abstract data type, sequence, achieves loop invariant and non-recursive Apla abstract algorithm. The Apla algorithm is verified formally, and further transformed to C++ program by related tool and component library. The theoretical analysis and experimental results show that the time complexity of new algorithm is little affected by bag capacity.
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Computer Engineering. 2008, 34(17): 39-41. https://doi.org/10.3969/j.issn.1000-3428.2008.17.015Discretization is an effective technique to deal with continuous attributes for machine learning and data mining. Reasonability of a discretization process is determined by the accuracy of expression and extraction for informations. By analyzing a series of Chi2 algorithm, a new algorithm called Imp-Chi2 algorithm is proposed, which is based on attribute significance. The algorithm reasonably adjusts the sequence of disretization for attributes according to the level of attribute significance, and exactly discretes the real value attributes. The experiments are performed respectively with the results of discreted data by using C4.5 and SVM. In the process of the experiments, a selection method of training set according to class proportion is presented. The method overcomes the bad-distributed situation for random selection of training set. Experimental results show that the presented algorithm is effective.
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Computer Engineering. 2008, 34(17): 42-43,4. https://doi.org/10.3969/j.issn.1000-3428.2008.17.016Aiming at the problem of isomeric data share use among different information systems , this paper designs the follow chart and steps of isomeric data transform, analyzes some key technologies of isomeric data transform with the functionality and logicality advantages of the Object Pascal language. It presents a dynamic defining, verifying, compiling and executing method, and describes the implementation processes of isomeric data transform. It is proved by practice that these methods are feasible and have great transform efficiency.
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Computer Engineering. 2008, 34(17): 44-46. https://doi.org/10.3969/j.issn.1000-3428.2008.17.017Traditional Linux file system such as ext2 performs poorly if large numbers of small files exist. This is due to the linear search algorithm of the file system. This paper implements SmallFS to solve this problem. SmallFS is one kind of storage optimization. It optimizes the search algorithm to greatly improve the performance. SmallFS is based on the stackable file system technique, so it has good compatibility and is transparent to users.
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Computer Engineering. 2008, 34(17): 47-49. https://doi.org/10.3969/j.issn.1000-3428.2008.17.018High dimensional large data has posed great challenges to most existing algorithms for frequent patterns mining. This paper decomposes the mining task into two parts: mining short frequent itemsets and long frequent itemsets, and proposes a new algorithm, i.e., inter-transaction, to find all long frequent closet patterns in large high dimensional dataset. The new algorithm utilizes the characteristic that the intersection of long transactions is usually a very short itemset, and can find long closet patterns directly via intersecting relevant transactions. In addition, the algorithm adopts a new pruning strategy to cut down search space and optimizes the performance of intersection of transactions. Experiments on synthetic data show that this method achieves high performance in large high dimensional dataset.
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Computer Engineering. 2008, 34(17): 50-52,5. https://doi.org/10.3969/j.issn.1000-3428.2008.17.019Nowadays, the embedded RFID middleware develops slowly, and it causes some hindrance to the widely application of RFID technology in mobile platform. This paper researches and develops an embedded RFID serviced assembly named EmbedMid, which can be applied in many kinds of application scenes and support multiple platforms, demonstrates a mobile management platform’s architecture based on the EmbedMid, and gives the lack of EmbedMid and the future research direction.
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Computer Engineering. 2008, 34(17): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2008.17.020To implement the complex spatial functions, many different GIS services need to cooperate and be integrated together. Due to the current OGC GIS service can not store the state information and need to send the same parameters repeatedly, the performance of it is relatively low. It also leads to the independent problem among these services. Aiming at these questions, the paper illustrates a method to improve the OGIS service according to the requirement of grid computing and WSRF. And it designs and implements a prototype grid map service system using the open source grid toolkit-Globus and Geoserver. Through the process, it illustrates how to improve the existing OGIS service to get more flexible data sharing and integration through making it grid enabled.
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Computer Engineering. 2008, 34(17): 56-58,6. https://doi.org/10.3969/j.issn.1000-3428.2008.17.021Aiming at the weakness of traditional data mining algorithm, this paper presents an optimized algorithm for mining association rule based on two matrixes. This algorithm can convert a transaction database into two matrixes through scanning the database only once, and does the mining work of two matrixes that include all information of items in database. The two matrixes are better in memory because they store logic data only. Frequent 1-itemsets and frequent 2-itemsets can be got directly based on Matrix MA and maximum frequent itemset can be got based on Matrix MB. Other frequent k-itemset is got based on the two matrix and the gotten frequent itemset, and the number of candidate itemset can be reduced. Logic operation is adopted so that the algorithm has predominance in efficiency. Experiments show that the algorithm is feasible and efficient.
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Computer Engineering. 2008, 34(17): 59-61. https://doi.org/10.3969/j.issn.1000-3428.2008.17.022Outlier detection is a hot research field in knowledge discovery in databases, such as credit card fraud, and intrusion detection, etc. Finding the rare abnormal behaviors or the outliers can be more interesting than finding the common patterns. This paper proposes a new outlier detection algorithm based on Local Deviation Factor(LDF). This algorithm counts the number of each point’s LDF to reflect its isolation degree. The experimental results show that this algorithm can efficiently detect outliers and has higher efficiency than outliers detection algorithm LSC.
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Computer Engineering. 2008, 34(17): 62-64. https://doi.org/10.3969/j.issn.1000-3428.2008.17.023This paper presents an adaptive scheduling mode and algorithm based on tree grid. This mode can schedule fine-grained tasks and big jobs adaptively. Through the real-time detection of grid, an adaptive grid load-balancing algorithm(Optimization-based Priority-Completion Time Heuristic Algorithm for Task Allocation, OPCTHATA) for task allocation is proposed, which is based on load state, task execution time, task transmission time and task properties. The experiments show that the proposed algorithms for the scheduling problem have better performance than other algorithms on load-balancing and optimum makespan.
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Computer Engineering. 2008, 34(17): 65-67,7. https://doi.org/10.3969/j.issn.1000-3428.2008.17.024Large amounts of heterogeneous complex data reside on different computers connected to each other by networks. Distributed clustering is an important implementation of large data process. Based on the Density Based Distribute Clustering(DBDC) algorithm, this paper proposes an improved algorithm. It gets better representatives bojects by local clustering, and sends these representatives with some other correlative information to the main computer. They are clustered with an enhanced clustering algorithm based on density. The clustering of sub computer is updated. Theoretical analysis and experimental results testify that this algorithm outperforms DBDC in both clustering quality and efficiency.
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Computer Engineering. 2008, 34(17): 68-70. https://doi.org/10.3969/j.issn.1000-3428.2008.17.025The component of track-debugging for component Operation System(OS), which has both logic debugging function and performance debugging function, is proposed in this paper. The log service for component and the control of process by component syscall are setup, so that this component of track-debugging can adapt component operation system’s need in distributional application. This component is implemented in laboratory and represents good characteristic for extending and transplanting.
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Computer Engineering. 2008, 34(17): 71-73. https://doi.org/10.3969/j.issn.1000-3428.2008.17.026Aspect Oriented Programming(AOP) can be used to avoid the disadvantage to the core code caused by cross-cutting concerns. However, because the method-signature pattern of the AOP can not express the cross-cutting concerns of the system exactly, matching some cross-cutting concerns by capturing the join point directly decreases the readability and modularity of system. A method for improving the definition of cross-cutting concerns of logging is studied in this paper. Such method improves the readability and the maintainability of the program, as well as implementing the flexibility of logging content.
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Computer Engineering. 2008, 34(17): 74-76. https://doi.org/10.3969/j.issn.1000-3428.2008.17.027This paper, based on the technology of building C compiler in embedded system, discusses the mainly work in realization of C compiler with design examples. The paper presents the design principle and the form method of the middle description language DAG, which has the bridge function between front end and back end. Also this paper describes the relation from DAG to target machine system, puts forward rules in maps about the method and principle of the rule establishment, and gives some experience conclusions that have guided meaning.
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Computer Engineering. 2008, 34(17): 77-78,8. https://doi.org/10.3969/j.issn.1000-3428.2008.17.028This paper designs and implements UML modeling system based on Web with MVC design pattern, which aims at development in different places and information query need under network environment with different composition. In order to express structured data and semistructured data in UML modeling, it saves modeling information as XML file, which has better expandability, opening property, elasticity, self description, operation property and regular architecture, and establishes information query based on XML to raise query efficiency.
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Computer Engineering. 2008, 34(17): 79-81. https://doi.org/10.3969/j.issn.1000-3428.2008.17.029To realize the availability and stability of online extending, this paper proposes a new scheme by integrating the idea of dynamic loading into software updating. Supervisor instruction, the concept of symbol resolution and lazy binding are used in the new scheme to set up the tree-like index for symbols of the system. The namespace pollution problem is addressed in the new scheme, and the security of the system and the accuracy of the symbol bindings are improved. It decreases the expenses for updating external reference during online extending significantly.
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Computer Engineering. 2008, 34(17): 82-84,8. https://doi.org/10.3969/j.issn.1000-3428.2008.17.030Many application-layer multicast protocols are short of definite reliable transmission mechanisms. This paper changes the topology of control and data in NICE protocol, uses ring and minimal delay tree, and adds the corresponding error control mechanism to improve the reliability of NICE. Simulations show that the improved protocol has complete reliability in case all nodes work well and achieves a high delivery ratio when some nodes fail.
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Computer Engineering. 2008, 34(17): 85-87. https://doi.org/10.3969/j.issn.1000-3428.2008.17.031Aiming at existed deficiencies such as network efficiency reduction and long search waiting time in P2P whole-length search, a topic relative search routing algorithm based on k-high frequency term is developed. In the algorithm, topics are expressed by k-high frequency term, and the topic relative network is formed. On the topic relative network, search requests are routed to the nodes which hold more resource firstly in order to search more resource by less time and network traffic. In the algorithm, the efficiency and validity is validated by the experiment. By antitheses analysis, result shows that the algorithm has less search waiting time and network traffic than simple flooding.
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Computer Engineering. 2008, 34(17): 88-90. https://doi.org/10.3969/j.issn.1000-3428.2008.17.032The most immediate effect of object-based storage is the offloading of space management from storage applications. MetaData Server (MDS) is responsible for the logical view management and provides unique naming space. To play an important role of navigation for MDS, this paper proposes a method of master/slave/standby chain backup. It can provide a continuous serving and ensure high reliability of MDS without adding any hardware device.
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Computer Engineering. 2008, 34(17): 91-92,1. https://doi.org/10.3969/j.issn.1000-3428.2008.17.033IEEE802.11 multi-rate mechanism OAR can better utilize wireless channel conditions, but it does not work well in the congestion network environment. This paper improves the OAR algorithm, whch increases the probability to obtain the channel of the congestion node by adjusting the initial competition window size. So they can transmit the congestion pakets as soon as possible, thus congestion is relieved. Simulation results indicate the ratio of packet delivering of OAR is improved.
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Computer Engineering. 2008, 34(17): 93-95. https://doi.org/10.3969/j.issn.1000-3428.2008.17.034This paper designs and implements a grid computing named NoMan-Grid without central management. The architecture, information management and recursive resource schedule algorithm of this system are presented. In this system, there is no managing node, and all the nodes have the same function. The preliminary performance of tests and analysis for NoMan-Grid are made, and the results show that this grid computing can harvest the idle time of Internet connected computers to run very large distributed applications with little Web communications which are statuesque distributing.
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Computer Engineering. 2008, 34(17): 96-98,1. https://doi.org/10.3969/j.issn.1000-3428.2008.17.035This paper analyzes the mechanisms and characteristics of two primary construction models for UAVs. Some new multi-level hybrid construction models, which are suitable to the application of Massive UAVs(MUAVs), are brought forward and discussed. An adaptive construction model and its key issues are studied based on the (quasi-)static models above. Simulation results show that these models are effective to reduce costs, and to improve the reliability and robustness of a MUAVs.
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Computer Engineering. 2008, 34(17): 99-101,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.036Based on performance analysis of the framework of HMIPv6, a new network framework combined with tree and distributed framework is proposed. The new network frame can solve the shortcoming of MAP discovery protocol in the HMIPv6, and the problems that high-level MAP is a bottleneck and improves the robust of mobile IP. Thus giving the selective arithmetic separately for the two framework, which demonstrates it can be suitable for various networks. So it can be used for wide range.
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Computer Engineering. 2008, 34(17): 102-104. https://doi.org/10.3969/j.issn.1000-3428.2008.17.037Network load balancer is efficient to enhance network performance. This paper studies different load balance systems and algorithms. By comparing those load balance algorithms, it adopts dynamic feedback load balance scheduling algorithm based on agent. This system is designed by combining with Intel IXP425 network processor and VxWorks5.5 embedded operating system. In laboratory environment, the balancer is used to balance proxy server load and has a good performance. Experimental result indicates the design is appropriate to use as a medium-sized network load balance equipment.
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Computer Engineering. 2008, 34(17): 105-107. https://doi.org/10.3969/j.issn.1000-3428.2008.17.038According to the handover latency caused by the duplicate address detection and home registration in the network environment of general mobile IPv6 handover, this paper anaylzes two address auto-configuration methods supported by MIPv6, combines AAA and the application of Diameter protocol with MIPv6, and brings forwards an MIPv6 address auto-configuration method based on authentication. This method combines AAA authentication, MIPv6 home registration and address auto-configuration, which can decrease the handover latency and enhance the security of network effectively.
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Computer Engineering. 2008, 34(17): 108-110. https://doi.org/10.3969/j.issn.1000-3428.2008.17.039Multiple isolated Network Address Translation Protocol Translation(NAT-PT) can not offer shorter path for a session, and all sessions via one NAT-PT may be broken and the IPv4 addresses may be wasted when NAT-PT failing. A Dynamic Routing NAT-PT(DRN) mechanism is presented to coordinate multiple NAT-PT working. With the pseudo route information which is broadcasted by DRN and shared information among NAT-PTs, NAT-PT becomes synchronous/friendly NAT-PT each other and achieves dynamic routing. A more appropriate NAT-PT is chosen to make path length of a session shorter and the load of a failure NAT-PT can be moved to a working one automatically.
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Computer Engineering. 2008, 34(17): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2008.17.040This paper puts forward intelligent network self-healing solution, which is based on the problems of commercial dedicated network. It does not change the network structure, but adds an intelligent network self-healing device between inside network and outside network. The device developed and produced by the authers can complete healing when the malfunction appears. The scheme designs and implements the system which adds a redundant hot-backup link of E1 link, so that E1 interface has the functions of auto-detecting, orienting and healing network malfunction. The system can complete self-healing operation by itself in 30 s.
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Computer Engineering. 2008, 34(17): 114-116,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.041To solve the problem of Session Initiation Protocol(SIP) traversing Network Address Translator(NAT), this paper describes a new method based on port detection. The scheme combines SIP user agent and STUN client, and adopts a method named port detection to obtain next port allocated by symmetric NAT. It brings that STUN can traverse most symmetric NAT and all other types of NAT. Some tests are made in real situations and the results reaches the goal.
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Computer Engineering. 2008, 34(17): 117-119. https://doi.org/10.3969/j.issn.1000-3428.2008.17.042The authentication system based on IEEE802.1x protocol has more advantages in LAN access, but it still has some problems and flaws based on the practice of network management. This paper gives a brief introduction to authentication architecture of the 802.1x protocol, the whole work theory, authentication mechanism and process of the system based on 802.1x and RADIUS protocol is discussed. An amelioration of the authentication system is presented. As a new element, the network flux is added to participate in its authentication. The project has advantages of automatic authentication and high efficiency in control.
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Computer Engineering. 2008, 34(17): 120-122. https://doi.org/10.3969/j.issn.1000-3428.2008.17.043To establish a valid cluster structure of Ad Hoc network for effective use of multi-channel and enhancement of system capacity and network performance, an improved algorithm based on the high connectivity clustering algorithm is proposed. By using the broadcast channels and confining the size of cluster, the algorithm realizes the multihop clustering from normal node to cluster head. The performance of the algorithm is envalued by simulation. Results indicate that the proposed algorithm keeps more suitable clustering numbers and enhances the load balancing of cluster head.
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Computer Engineering. 2008, 34(17): 123-126. https://doi.org/10.3969/j.issn.1000-3428.2008.17.044This paper puts forward an implementation scheme, which is called Network Address Translation(NAT)/Network Address Port Translation(NAPT) based on programmable Network Processor(NP) IXP2400 and GP-CPU. Meanwhile, the NAT firewall system with firewall function, containing a pair of Intel IXP2400 and GP-CPU, is designed and implemented. And the performance analysis of the NAT Firewall system is made, which can support more than six hundred thousand of concurrent TCP/UDP sessions and sustain the full line rate on two Gigabit Ethernet links. In addition, the NAT Firewall system can successfully achieve the multiplexing of network address, effectively improve the performance of NAT/NAPT processing and overcome the bottleneck of performance in traditional implementation of NAT.
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Computer Engineering. 2008, 34(17): 127-129,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.045The construction and validation of cross-certificate chain usually need plenty of time, which limits its extensive application. Based on a hybrid trust model supporting cross-certification, this paper puts forward two optimizing algorithms about adding path validation into path construction, which support cross-certificate forward path construction on the searching basis of depth first and adjusting strategy tree and sequence validation in the path validation. By these methods, the efficiency to the path construction and the path validation and the availability of cross-certificate are improved.
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Computer Engineering. 2008, 34(17): 130-132. https://doi.org/10.3969/j.issn.1000-3428.2008.17.046This paper describes a graphic verification tool for security protocol based on GSPM with formal methods. Linear Temporal Logic(LTL) is introduced to show the property of security protocol. This tool can find out the bug of security protocol using the model-checking method based on searching states. The simplified needham-schroeder public-key authentication protocol is used to exemplify the automatic verification process of security protocol with this tool, and results show the validity and correctness of the verification algorithm.
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Computer Engineering. 2008, 34(17): 133-135. https://doi.org/10.3969/j.issn.1000-3428.2008.17.047In order to prevent the database of the bank expanding infinitely and improve the performance efficiency of the system, this paper proposes an off-line e-cash system with validity duration based on the smart card by adding the validity duration into electronic cash system. The system applies the signature based on the elliptic curve to realize. As the capability of the smart card is limited, and the elliptic curve can achieve much better security and only need much shorter keys, the elliptic curve is much more adapt to e-cash system based on smart card than the discrete logarithm. The system is based on expression question of elliptic curve dispersed number, so its security is based on the security of elliptic curve dispersed logarithm.
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Computer Engineering. 2008, 34(17): 136-138. https://doi.org/10.3969/j.issn.1000-3428.2008.17.048This paper proposes an Event Triggering Based Adaptive Selection(ETBAS) algorithm of monitoring nodes, which introduces the mechanism of monitoring states and the method of event triggering. Triggering events, for example, a node is voted to be a monitoring node by its neighbors, the battery power of a monitoring node consumes to a threshold, or the networks topology changes, can awaken a non-monitoring node, or make a monitoring node fall sleep. The ETBAS is adjusted to the dynamic changing topology of Ad Hoc networks, whether a monitoring node leaves or a new node joins, its neighbors will be informed, and exchange battery power information to automatically re-choose new monitoring nodes in local network.
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Computer Engineering. 2008, 34(17): 139-140,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.049Automated trust negotiation is an iterative process that establishes trust gradually between strangers by requesting and disclosing digital credentials. Protection of sensitive information in automated trust negotiation has been drawn much attention. In order to solve this problem, formal definition of relevant attributes is given. Relation model of relevant attributes is designed. A desideratum of policy for relevant attributes based on the relation model is presented. And the desideratum is enforced in a relevance contractor, which is an addition to the policy database system as improvement. The relevance contractor is used to check whether the policies satisfy the desideratum.
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Computer Engineering. 2008, 34(17): 141-143. https://doi.org/10.3969/j.issn.1000-3428.2008.17.050Time-based cache attacks analyzes the time difference in the execution of algorithm over a processor, and recovers the secret key. This paper investigates such an attack on AES. A modified version of this attack is shown. It can be applied in most AES software, and implemented against OpenSSL v.0.9.8(a) and Miracl running on PentiumⅢ. The attack is shown under optimal conditions to recover a full 128-bit AES key with 224 timing samples, less than 228 of the previously attack. It gives several countermeasures of such attack.
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Computer Engineering. 2008, 34(17): 144-146. https://doi.org/10.3969/j.issn.1000-3428.2008.17.051Mobile Ad hoc Networks (MANET) is suffering from the threat of variety of attacks for its dynamic topology and wireless channel features. This paper presents an attack detection policy based on data link monitoring with support of secure routing protocol, which aims at traffic pattern distortion attacking. The nodes on data link monitor the behaviors of the previous and next nodes to assure the security of data link on a base of trustworthy routing information. Analysis and simulation results show that the policy is efficient.
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Computer Engineering. 2008, 34(17): 147-148,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.052Threshold signature is a kind of special and important digital signature. But in the existing threshold signature scheme, conspiracy attack is still a problem which is difficult to solve. This paper analyzes a threshold signature scheme to withstand conspiracy attack, analyzes its weakness and proposes some heuristic idea and methods to withstand conspiracy attack based on the existing threshold signature schemes.
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Computer Engineering. 2008, 34(17): 149-152. https://doi.org/10.3969/j.issn.1000-3428.2008.17.053This paper proves a lemma of how to preserve high order statistics based on analyzing the decomposition characters of discrete Haar wavelet. According to this lemma, it proposes a spatial steganograph algorithm. It can preserve high order statistics of H, V and D areas, and make embedded messages sightless. Experimental results show that it can effectively resist RS attack. It arises some inspiration for constructing better steganograph methods to preserve high order statistics.
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Computer Engineering. 2008, 34(17): 153-154,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.054Using stego-key to control embedding path becomes a trend. Software attack is increasingly unable to meet the real-time requirement of steganalysis as the length of secret message and the key space increases. An FPGA-based steganalysis scheme against key-dependent steganography F5 is proposed. The embedding paths produced by correct key and wrong keys have obvious difference in distribution of samples. This phenomenon can be used to get the correct stego-key of F5, thereby the attack succeeds. Experiments show that as the length of message exceeds 2 000 bit, this scheme can decrease a magnitude order of time compares with software attack.
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Computer Engineering. 2008, 34(17): 155-157. https://doi.org/10.3969/j.issn.1000-3428.2008.17.055Because Shum-Wei anonymous proxy signature scheme has weakness of original signers forge attack and low implementation efficiency of the construction of discrete logarithm problem, this paper proposes a new anonymous proxy signature scheme based on ECC, and analyzes the essential security characters it has. It shows that the new scheme has the quality of high security and high efficiency of implementation.
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Computer Engineering. 2008, 34(17): 158-161. https://doi.org/10.3969/j.issn.1000-3428.2008.17.056This paper presents a double zero-watermarking algorithm based on transform domain and hyperchaotic iteration. It uses the important coefficients of Discrete Cosine Transform(DCT) domain and Discrete Wavelet Transform(DWT) domain to constructure zero watermarkings separately, uses a hyperchaotic sequence to encrypt, so that the robustness, invisibility and security are improved. Experimental results show that the algorithm improves the integrated performance of the watermarking system.
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Computer Engineering. 2008, 34(17): 162-163,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.057Forward security signature scheme satisfies forward security. However, the scheme is not secure if signature’s secret key is revealed. For this reason, this paper proposes a new strong forward security proxy signature scheme combining strong forward security and proxy signature, which introduces strong forward concept and overcomes limitation of the previous scheme.
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Computer Engineering. 2008, 34(17): 164-166. https://doi.org/10.3969/j.issn.1000-3428.2008.17.058A delayed Susceptible Infectious Recovery Susceptible(SIRS) model on malicious codes is presented in the paper. The competition between malicious code and anti-virus software leads to the situation: susceptible computers are infected and become infectious, and then these infections become recovery because anti-virus software is run. When these viruses upgrade and vary, those computers with anti-virus software have temporary immunity only. Moreover, the effect of time-delayed is studied in the model. Equilibrium points and their stabilities of this model are analyzed. The delayed model better describes long-term condition of malicious code.
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Computer Engineering. 2008, 34(17): 167-169. https://doi.org/10.3969/j.issn.1000-3428.2008.17.059This paper analyzes the theoretical security model which is proposed by Christian Cachin, and applies this model to evaluate the statistical imperceptibility of information hiding. This evaluating method removes correlation by blocking image, and uses Discrete Cosine Transform(DCT) to get the image’s stationary probability distributions. It computes DCT coefficients’ joint probability distributions to evaluate information hiding algorithms’ statistical imperceptibility. Results of experiments indicate that this method not only can be good for evaluating statistical imperceptibility, but also can guide information hiding algorithm’s design.
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Computer Engineering. 2008, 34(17): 170-172. https://doi.org/10.3969/j.issn.1000-3428.2008.17.060This paper extends previous results bridging the gap between the symbol approach and the computational approach. Specifically, for the case of protocols that use signatures, based on the Micciancio-Warinschi method, the soundness of digital signature with respect to the computational model is established, i.e. if digital signature scheme is N-UNF, then the results obtained form the symbolic model carry over to the computational model. Based on this conclusion, a formal system with computational soundness can be consructed.
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Computer Engineering. 2008, 34(17): 173-175,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.061It is necessary to install some security equipment or system, such as IDS, firewall, integrality check system etc. to ensure network security. But, in this situation, not only would actual alerts be mixed with false alerts, but the amount of alerts would also be too much to manage. This paper presents a framework for security events, which is mainly composed of following steps: event collection, event preprocess, event condensation, event aggregation, attacks reconstruction and the result analysis. Through this process, the rate of false and miss alert to some extent can be reduced. The aggregation algorithm and attack reconstruction technology are described simply.
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Computer Engineering. 2008, 34(17): 176-177. https://doi.org/10.3969/j.issn.1000-3428.2008.17.062This paper researches the Yahalom protocol and its variants, finds a sequence flaw existing in them and provides a kind of method to attack them by using the flaw. The Yahalom protocol has been revised several times, and no key-compromise problem is proved in the final Yahalom-Paulson protocol, but the Yahalom protocol and its variants still have the sequence flaw which has never been paid attention before. The Yahalom-Paulson protocol is improved from the angle of sequence. The improved Yahalom-Paulson protocol preserves the security of the original protocol, and can resist the attack caused by the sequence flaw.
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Computer Engineering. 2008, 34(17): 178-179,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.063To guarantee access security in network collaborative enterprise modeling systems, establishing access control function is in demand. Based on study of the role-based access control, discretionary access control and mandatory access control, combined with the characteristic of the collaborative enterprise modeling system, a role and task based dynamic access control with limitation of the enterprise model node state is proposed. In this method, user’s position, the tasks performed by this position and the role are confirmed, the corresponding model node status are examined. And the access authorization is established. These are convenient for realizing the grained security administration to users and objects. Based on the specification, system realization method is presented.
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Computer Engineering. 2008, 34(17): 180-182. https://doi.org/10.3969/j.issn.1000-3428.2008.17.064Buffer overflow attack now becomes the main reason for the happening of security events. The MS07-017 animated cursor handling vulnerability presented by Microsoft is a stack overflow vulnerability rated as critical. This paper is mainly focused on the buffer overflow principle and exploitation on Win32 platform, and takes the MS07-017 animate cursor handling vulnerability as example to demonstrate the concepts. An in-depth analysis of this vulnerability is also presented in the paper to reveal how it occurs and a discussion of how to write the shellcode is available. A mal-formed animated cursor file generator is coded to prove the analysis.
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Computer Engineering. 2008, 34(17): 183-185. https://doi.org/10.3969/j.issn.1000-3428.2008.17.065A problem that child role cannot obtain private permissions because of inherited relation in the Role-Based Access Control(RBAC) model is researched. The specific permission of the roles in same department or similar business, is not discussed in the past solutions, and the permission cannot be inherited by multi father role. Thus a new solution with domain and domain’s permission is presented. The method of permission management is analyzed, an algorithm to inherit permissions from one child for multi father roles is provided, and the question of inheritance is solved. The access control theory based on role and domain in the application system is realized.
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Computer Engineering. 2008, 34(17): 186-187,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.066Open domain Question Answering(QA) represents a challenge of natural language processing, aiming at returning exact answers in response to natural language questions. Pattern matching is an effective strategy for QA. This paper demonstrates the technique of pattern generalization and its applications in QA. There are two important applications of pattern in QA. Pattern-based query expansion retrieves more exact snippets including the correct answer and the performance is improved. Another application is the answer extraction which applies the pattern matching approach. Experimental result on TREC data indicates that the pattern matching method is effective.
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Computer Engineering. 2008, 34(17): 188-190. https://doi.org/10.3969/j.issn.1000-3428.2008.17.067The increasingly huge volume of digital images stored in computer are characterized by implicit semantic, disconnected storage and inconvenient in retrieval, thus result in low efficiency in image using. This paper proposes the ImageQ which is an ontology-based annotation and retrieval model for image semantic. It features the layered and modular architecture and independent of the domain ontology, supports domain ontology evolution and several image retrieval methods in different depth of reasoning. The running results of a experimental system based on ImageQ show that the model well performed in image management and intelligent retrieval.
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Computer Engineering. 2008, 34(17): 191-192,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.068Progressive Transductive Support Vector Machine(PTSVM) has some drawbacks such as slower training speed and unstable learning performance. This paper proposes a Near Neighbor Progressive Transductive Support Vector Machine(N2PTSVM) learning algorithm. Making full use of support vectors in SVM, the method selects new unlabeled samples near support vectors. In addition, the method introduces pre-extracting support vector algorithm to reduce the calculation complexity. Experimental results show its validity.
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Computer Engineering. 2008, 34(17): 193-195. https://doi.org/10.3969/j.issn.1000-3428.2008.17.069The traditional disease diagnostic expert system only has a single reasoning process to use knowledge, so that its knowledge utilization is inefficient. Its conclusion has low accuracy and without contrast. This paper makes example of goat, modelings disease diagnostic knowledge base by the use of object-oriented knowledge representation. According to the training process and diagnostic model, it proposes the ideology of multi-engine ruling based on one knowledge base, multi-tract to operate knowledge, constructing the object-oriented weighted uncertain judgments and decisions basis on samples matching algorithm. Experimental results show that multi-engine diagnostic model can improve the utilization rate of data resources in knowledge base, improve the accuracy of diagnosis, increase the contrast.
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Computer Engineering. 2008, 34(17): 196-199. https://doi.org/10.3969/j.issn.1000-3428.2008.17.070This paper proposes a video tracking system for moving vehicle based on region and several improved techniques of the system. The tracking quality based on region lies on the detecting results. A hybrid difference strategy is introduced to attain higher detecting quality than other methods. A stack searching and a discriminating rule are designed to optimize the vehicle recognition. Experimental results indicate the video tracking system is feasible and useful in application of intelligent transportation system.
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Computer Engineering. 2008, 34(17): 200-201,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.071This paper analyzes the feature of 3D face recognition, and presents a 3D face recognition algorithm based on 2D Gabor wavelet feature. This algorithm uses 2D Gabor wavelet feature to describe features on human face accurately and stably. The 3D face recognition is performed by three steps: 3D face model reconstruction, pattern matching of reconstructed 3D face model and Linear Discriminates Analysis of matched 3D face model. The experimental result based on ORL and UMIST databases shows that this method has excellent performances.
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Computer Engineering. 2008, 34(17): 202-204. https://doi.org/10.3969/j.issn.1000-3428.2008.17.072Based on whole qualitative analysis, this paper compares and validates merits and demerits of various edge detection algorithms in a quantificational way from several typical judgement standards for edge detection algorithms like edge connectivity, nosie resistence ability, operation complexity. By means of B cubic spline interpolation, it improves the quality of the detected images. Experiental results show that this methods can be well applied in the region of image processing.
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Computer Engineering. 2008, 34(17): 205-207,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.073This paper proposes a particle swarm optimization based on local and global combined search. Combining the strongpoint of local search and global search, the new algorithm reduces the possibility of trapping at the local optimum. The advanced algorithm maintains the characteristic of fast search in the early convergence phase, and improves the global search ability. Experimental results indicate that Local and Global Combined Particle Swarm Optimization (LGCPSO) has the advantage of convergence property over PSO. The algorithm avoids the local convergence problem effectively, and has the ability to get a convergence velocity quickly.
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Computer Engineering. 2008, 34(17): 208-210. https://doi.org/10.3969/j.issn.1000-3428.2008.17.074This paper presents a method for restaurant reviews mining based on semantic polarity analysis. It regards the taste, environment, service and price as the restaurant features. The user reviews are tagged with features sentence by sentence, and the complicated sentences with multi-features are divided into several simple feature sentences. It analyses the sentences’ semantic polarity and its intensity. As a result, the user can find out others’ opinions on certain restaurant about its certain feature conveniently. It provides useful guidance for the user.
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Computer Engineering. 2008, 34(17): 211-213. https://doi.org/10.3969/j.issn.1000-3428.2008.17.075Matching engine is not simpls simple search, but absolutely in-depth information mining. This paper explains a construction of a matching engine based on simple Bayesian network. By modeling, it designs the four kinds of node set into a four-tier Bayesian network, mainly to mark and select the input samples. In this model, all tiers have meaningful conditional probability between them, which, to some extent, has solved “wrong results” and “few results” problems. Experiments prove the model can search more precisely.
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Computer Engineering. 2008, 34(17): 214-215. https://doi.org/10.3969/j.issn.1000-3428.2008.17.076This algorithm adopts a dynamic variable length coding method. It uses grids to indicate the environment and simultaneously aims at the genetic algorithms large-scale barrier to the problem by using the act of follow wall. So it well solves the difficult problem based on genetic algorithms rapid path planning and obstacle avoidance major obstacles. The algorithm adapts to any form of the barrier, and is suitable for static environment and dynamic environments. Computer simulations show that the algorithm is a correct and efficient path planning method.
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Computer Engineering. 2008, 34(17): 216-218. https://doi.org/10.3969/j.issn.1000-3428.2008.17.077Security is critical to a wide range of current and future wireless data applications and services. This paper introduces the security strategy and the security implementation for ZigBee access to EPA network. Test shows that the implementation of the security strategy improves the reliability of the EPA network. These security device, which can be configured, can run steadily and meet the need of the industry control system.
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Computer Engineering. 2008, 34(17): 219-221. https://doi.org/10.3969/j.issn.1000-3428.2008.17.078This paper presents a new baseband-processor for Wireless Sensor Network(WSN) node based on ZigBee protocol. A dedicated demodulation architecture based on a non-coherent receiver algorithm is proposed to enhance the receive sensitivity and reduce the circuit redundancy. A new transceiver control unit is designed to manage the whole transmit and receive process. Other techniques, such as operation mode switch, power management, software platform optimization etc. are also implemented to reduce the power consumption as well as chip area. The design is implemented and verified in Altera Stratix S80 FPGA platform. Test results prove its expected functionality and its low power consumption.
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Computer Engineering. 2008, 34(17): 222-224. https://doi.org/10.3969/j.issn.1000-3428.2008.17.079This paper proposes a design of portable Electrocardiogram(ECG) monitor based on 32 bit embedded technology. The monitor equips an ARM920T-based microprocessor EP9315 as its main controller, and contains many other components such as ECG amplifiers, AD convertors, LCD display with touchscreen, GPRS module, and data storage device. It utilizes the Linux operating system and Qt/Embedded GUI, and has stable performance and friendly operating interface. The instrument realizes the acquisition, storage, display, automatic analysis and network transmission of human ECG signals.
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Computer Engineering. 2008, 34(17): 225-226,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.080This paper proposes a technology for dynamic program loading based on TI TMS320C5410 DSP. By using this technology, the limitation in bootloader program of Digital Signal Processor(DSP) is solved and any bytes long program can be loaded selectively, optimal configuration of resources in DSP are implemented. Dynamic program loading and release in the running process is realized, the optimal reconfiguration of resources in DSP is done, and online update and online debugging of program in DSP are developed.
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Computer Engineering. 2008, 34(17): 227-228. https://doi.org/10.3969/j.issn.1000-3428.2008.17.081By analyzing the method of dispatch for production of electrochemical enterprise, this paper puts forward the design of dispatch for production system based on network and Web technology. The system includes energy data acquisition subsystem, network subsystem, and energy supervisory control and management subsystem. Collection subsystem based on RS485 series is constructed by using industrial computer and OLE for Process Control(OPC) technology. Dispatch for production system based on Ethernet network is constructed with Web server, history/real database server and brower, and dispatch for production system is introduced.
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Computer Engineering. 2008, 34(17): 229-231. https://doi.org/10.3969/j.issn.1000-3428.2008.17.082In order to improve performance of multiplier, this paper adopts modified Booth algorithm to generate partial product, proposes the leapfrog Wallace tree architecture to compress partial product, and introduces the modified LING adder to compute the final sum of the result of Wallace tree. The design is realized by using Altera’s FPGA. Synthesis, placement and routing of 32-bit multiplier are accomplished on 0.18 μm SMIC process. Compared with conventional multiplier with traditional Wallace tree, the multiplier reduces the multiplication time, the power dissipation and the area of multiplier by 29%, 38% and 17%.
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Computer Engineering. 2008, 34(17): 232-234. https://doi.org/10.3969/j.issn.1000-3428.2008.17.083There are more and more data such as voice, text, picture and video transferring in Internet, which leads the problem of speed bottleneck. According to the problem, this paper designs the high-speed Low-Voltage Differential Signals(LVDS) transceiver by full-custom design flow with the technology of low power and low common mode voltage. Simulation experiments show that the transceiver supports 200 Mb/s transmission speed and it is thoroughly compatible with IEEE1596.3-1996.
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Computer Engineering. 2008, 34(17): 235-236,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.084Based on polarized light, this paper developes fiber maturity system. SCM has the merits of high integration, high performance, high reliability, simple structure, application flexibility and low price. Based on polarized light detection principle, automated detection and intelligence are realized by using SCM. The machine scans the cotton fiber and outputs as light, with A/D transferring. The digital figures are calculated in SCM, compares them with the standard value, and outputs the relative error output.
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Computer Engineering. 2008, 34(17): 237-239,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.085Intelligent image card is the key of system based on the classic hotel and guesthouse’s layout structure that there is an aisle between two line rooms.To different from others network entrance guard systems, it has particular embranchment topology fabric, efficient energy saving and many humanizated designs. The prototype aeroplane tries out that all main functions of the system has reached a practical request. Cost and humanization advantages contribute to pushing forward traditional network entrance guard systems development.
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Computer Engineering. 2008, 34(17): 240-241,.High reliability computer application needs the ability which the computer is fault tolerant, and requests high level CPU. This paper discusses a two module fault tolerant computer, which is based on PC8245 processor and FPGA. Because of the limited space, this computer uses distributed arbitration architecture, the arbitration logic runs in FPGA of the master computer and the backup computer. The finite state machine of the arbitration architecture and the mechanism of the communication interface redundancy control are discussed.
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Computer Engineering. 2008, 34(17): 242-244. https://doi.org/10.3969/j.issn.1000-3428.2008.17.087This paper analyzes the problems in short message service system in bank, and introduces the design ideas of the new system, including the main functions, the developing skills, the critical data structures and codes. This system reduces the coupling between the short message service engine and the practical application with the ideas of service oriented design and hierarchical design, and improves the performance of the system and the ability of maintenance. Experimental results show that it can keep good running.
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Computer Engineering. 2008, 34(17): 245-247. https://doi.org/10.3969/j.issn.1000-3428.2008.17.088Snapping traffic rule-breaking behavior such as vehicle over-speed requires detecting vehicle’s speed accurately. There are some problems with the conventional loop detector, which can’t detect vehicle’s speed exactly. A kind of traffic data collection system which is used for detecting vehicle’s speed is designed. This system is mainly controlled by CPLD. It collects the data of vechicles by designing the correlative electrocircuit. The collected data is transmitted to the computer real-timely by the device of CH365. By further analyzing and processing, it outputs different information which meets the demand of different kinds of detection. The experiments results show that the system is reasonable, and can be effectively used for vehicle speed detection and other traffic detection system.
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Computer Engineering. 2008, 34(17): 248-250. https://doi.org/10.3969/j.issn.1000-3428.2008.17.089The traditional communication lines maintenance depends on the experts’ experience, which is inefficient. Based on the theory of WebGIS, a group of common client components are designed. They can realize the rapid development of WebGIS application system, and the quick switch between different platforms or different editions of the same platform. The communication lines maintenance WebGIS system is designed and realized. The efficiency is 4~5 times of the past.
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Computer Engineering. 2008, 34(17): 251-253. https://doi.org/10.3969/j.issn.1000-3428.2008.17.090In order to realize the full information management of the project material database, and the advanced inquiry based on the full information management of material information especially full text search, this paper analyzes the system function, and realizes the project material database system based on the full information management. It analyzes user’s dynamic data management and inquiry algorithms especially, puts forward and realizes a kind of full text search based on word collection picking-up, storing and match inquiry form file. The project material databases system provides inquiry instance to indicate advance and practicability of this method.
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Computer Engineering. 2008, 34(17): 254-256. https://doi.org/10.3969/j.issn.1000-3428.2008.17.091This paper introduces an improved gradual imbedding generation algorithm for Delaunay triangulated network. The data points are inserted sequentially to construct Delaunay triangulated network without additional sorting operation. Based on the original insertion, the algorithm improves the efficiency of Local Optimization Procedure(LOP) algorithm by updating adjacent triangles, which uses Delaunay rules upon the triangles formed by changing diagonal lines. Experiment indicates that the algorithm can improve the efficiency of the former one and accelerate the generation of Delaunay triangulated network.
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Computer Engineering. 2008, 34(17): 257-259. https://doi.org/10.3969/j.issn.1000-3428.2008.17.092OSEK/VDX specification playes an important role in the automotive electronic control system, and system performance is significantly affected by message transmission mechanism based on OSEK/VDX communication specification. This paper analyzes three transmission mechanisms in the external communication, and proposes a new optimization strategy for message transmission mechanisms which adds uncovered property in the message structure in order to deal with message loss phenomenon. Implementation method and test results are represented.
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Computer Engineering. 2008, 34(17): 260-262. https://doi.org/10.3969/j.issn.1000-3428.2008.17.093To reduce the difficulty of developing complex processes and improve the management efficiency of the application system, this paper proposes a workflow design scheme in hospital office automation system. According to the reference model of the workflow, this workflow management system implements workflow process definition and exchange interface, workflow client applications interface and system administration and monitoring interface, which consist of workflow definition module, workflow executive-control module and workflow monitoring module. It provides form design, workflow steps and moving definition. This workflow management system supports complex processes and satisfies the various needs of hospital business processes.
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Computer Engineering. 2008, 34(17): 263-265. https://doi.org/10.3969/j.issn.1000-3428.2008.17.094Aiming at the need of combat training and verifying the advanced flight control law, a sort of universal digital flight simulation platform is proposed in this paper. The structure of the flight simulation platform is introduced. The dynamic model of airplane and universal flight simulation database is constructed, and the function of each module and method to establish each module are fully illustrated. A validation in this platform for a sort of UAV is made. The simulation result shows that the platform acquires good visual effect and accurate parameters, simulating real flight well.
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Computer Engineering. 2008, 34(17): 266-268,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.095The informationization task has been developed from management system to decision-making system in universities. Data Warehouse is the core of this decision-making system. This paper summarizes the status and the problems in the college financial budget system, and analyzes the demand of building a data warehouse. The main techniques of designing the data warehouse system is presented. This data warehouse system is designed and implemented, which is analyzed by using OLAP. This system has been used in a university and runs well.
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Computer Engineering. 2008, 34(17): 269-270,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.096This paper presents a framework of multi-user roam system based on B/S architecture. The scene can be dynamically controlled by using Java script authoring interface of VRML. With messages transferred between the server and clients from the users and the scene itself, the communication and interaction among multiple users in the same virtual scene on the web are implemented. This system is also a general ideal model for other multi-user roam systems. An example of this application is showed, and the result shows this system is effective.
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Computer Engineering. 2008, 34(17): 271-273. https://doi.org/10.3969/j.issn.1000-3428.2008.17.097This paper puts forward a new order of color vector, which focuses on RGB color space with a combination of the revised distance order and lexicographical order based on the research on the color image morphology. Basic operators of color image morphology are introduced. By using basic operators of color image morphology, an algorithm of enhancement and an algorithm of filter of gray-image are extended to dispose color images. Experimental result demonstrates that the algorithms of color image morphology based on this order and reconstruction can better keep the peripheral information and an algorithm of enhancement and an algorithm of filter of color image based on this algorithm bring forth the quality of being salient.
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Computer Engineering. 2008, 34(17): 274-275,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.098Detecting deadlocks in MPI synchronization communication programs is very difficult, which needs building program models. All complex models are based on sequential models. The sequential model is mapped into a set of character strings and its deadlock detection problem is translated into an equivalent multi-queue string matching problem. An algorithm is devised and implemented to statically detect deadlocks in sequential models of MPI synchronization communication programs. This algorithm is better than usual circle-detection methods and can adapt well to dynamic message stream.
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Computer Engineering. 2008, 34(17): 276-278. https://doi.org/10.3969/j.issn.1000-3428.2008.17.099Virtual Reality(VR) provides an intuitive and immersive human-computer interface, which can be an efficient tool for maintenance training. Current research on VR for maintenance is mainly based on either immersive or augmented VR technology which is not practical due to high equipment cost. This paper presents a VR application for maintenance training, which is an object oriented prototype desktop VR-enabled system for maintenance. This system integrates a maintenance mode based on near optimal disassembly sequence with VR using the object oriented methodology. A case study on the maintenance for some type of mechanical device is used to illustrate that the system is effective.
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Computer Engineering. 2008, 34(17): 279-280,. https://doi.org/10.3969/j.issn.1000-3428.2008.17.100The performance of Web Geographic Information System(Web GIS) is not good when including mass of raster data, too many layers and spacial feature operations. This paper tests the Web GIS with different plans of database optimization and disk array, raster data’s compressing and pyramidal storage, layer’s amount and caches based on the ArcServer architecture of the ESRI company. Considering the enforceability in the real applications, it gives the optimization plans and analyzes the advantages and disadvantages.
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Computer Engineering. 2008, 34(17): 281-283. https://doi.org/10.3969/j.issn.1000-3428.2008.17.101The paper analyzes C/OS-II system, and adds some fault-tolerant operating modules based on multi-MCU modules. The modules achieve the coherent real-time operation for the current state of the running tasks. If one of the multi-MCU modules breakdowns, other MCU modules can judge the fault and resume bad system state to run on decision-making. The fault-tolerant real-time operating system, which shows a stable dependable fault-tolerant ability, has been tested on three MCUs.
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Computer Engineering. 2008, 34(17): 284-封三. https://doi.org/10.3969/j.issn.1000-3428.2008.17.102To satisfy the needs of the enterprise anti-counterfeiting and encryption, the digital anti-counterfeiting system is designed and implemented by means of the combinations of the digital anti-counterfeiting techniques and middleware techniques. This paper abstracts the category in the system logics, and presents the middleware service program, which runs well in this system. The stability and open ability of this system are improved. Through the implementation of this system, the ability of the enterprise anti-counterfeiting gets an overall promotion, which offers the basic data for decision-making system.
2024
Volume 50 No 3
Volume 50 No 3
(Started in 1975, Monthly)
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428