20 January 2011, Volume 37 Issue 2
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Computer Engineering. 2011, 37(2): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2011.02.001For the requirements of multi-source heterogeneous data query in information security development and research work, a multi-source heterogeneous data query middleware system is designed and implemented based on the analysis of network security data structure. This system applies and extends Language Integrated Query(LINQ) technology, achieves transparent query through query parsing, name mapping, specific expression tree generation and result set processing steps, and supports a variety of data sources, including popular databases, XML and JSON formats, etc. It is also easy for expansion and redevelopment.
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Computer Engineering. 2011, 37(2): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2011.02.002Due to the lack consideration of general and scalability in the existing simulators of Peer-to-Peer-Video-on-Demand(P2P-VoD) systems based on network coding, a general simulation platform based on NS2 is proposed. The network coding mechanism is extended on the basis of NS2. The Socket model and interface model are designed to provide P2P application. To complete the simulation platform, the P2P-VoD application models are designed and developed. Simulation results show that the data scheduling algorithm based on network coding can be simulated effectively with the proposed platform and the platform possesses general and scalability.
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Computer Engineering. 2011, 37(2): 7-9. https://doi.org/10.3969/j.issn.1000-3428.2011.02.003
In order to improve the detection speed and decrease the false alarm rate of the AdaBoost algorithm in high resolution color image, a multi-feature fusion method is proposed. It adopts cascade strategy to combine multi-fuse classifiers. Benefiting from the complementary of multi-feature, the proposed method can achieve high performance. Experimental result demonstrates that the proposed method has better global precision and is less time consuming.
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Computer Engineering. 2011, 37(2): 10-12. https://doi.org/10.3969/j.issn.1000-3428.2011.02.004Multipath signal delay estimation and interference mitigation in satellite navigation are research hotspots. According to the multipath signal nature of close specular reflection, an estimation algorithm based on UPF for the delay time of multipath is investigated. The standard particle filtering algorithm is presented, and the application of the Unscented Particle Filtering(UPF) algorithm in the estimation of the delay time of multipath is primarily discussed, and the algorithm is deduced in detail. Simulation results verify the effectiveness of this algorithm.
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Computer Engineering. 2011, 37(2): 13-15. https://doi.org/10.3969/j.issn.1000-3428.2011.02.005Based on Flexsim simulation platform, a 3D virtual reality simulation model of a large container terminal yard in China is created to assist its road planning. Combining the model with the road capacity theory, the appropriate width of the road in the yard is determined. The architecture, components and processes of the model are discussed. Through simulation experiments, the peak traffic flow data are obtained. Comparing the data with the road traffic capacity, it can judge the reasonableness of the road planning and make recommendations for improvement.
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Computer Engineering. 2011, 37(2): 16-19. https://doi.org/10.3969/j.issn.1000-3428.2011.02.006
The existed model on information-theoretically Secure Message Transmission(SMT) assumes t
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Computer Engineering. 2011, 37(2): 20-21. https://doi.org/10.3969/j.issn.1000-3428.2011.02.007The model of y~n curve is set up to solve the problem that discrete gene chip data are difficult to be systematically analyzed, which makes the data be changed into a row of sole signal, and can be studied by multi-scale analysis. Results of denoising the cerebral cortex gene expression of developing human brain based on wavelet multi-scale analysis show that the denoised effect of y~n curve is better than that of raw data.
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Computer Engineering. 2011, 37(2): 22-24. https://doi.org/10.3969/j.issn.1000-3428.2011.02.008The fuzzy set, rough set and quotient space theory are compared in details from the viewpoints of understanding of intelligence, representation of granules, measurement of granules and relationship among granules. Their commons are to think problem from a granular perspective, to define a granule by a set and to represent a knowledge by a granule; their main difference is that theory of computing with words and rough set theory focus on reasoning of words and attribute reduction from microcosmic level respectively, while quotient space theory discusses the translation rules of granules among the worlds with different grain-size from macrocosmic level.
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Computer Engineering. 2011, 37(2): 25-26. https://doi.org/10.3969/j.issn.1000-3428.2011.02.009This paper presents an algorithm, which travels the state diagram from the initial state to the ending state and finds all the transition paths. Test cases generation is based on test paths, which satisfies transition test criterion. It can optimize the length of the path, consequently reducing the number of test case based on cycle complexity. Experimental results indicate this algorithm is effective and feasible, and good effects are obtained in practical applications.
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Computer Engineering. 2011, 37(2): 27-29. https://doi.org/10.3969/j.issn.1000-3428.2011.02.010The R-tree method, which is a popular method used in spatial database, has limitations for Web map service. This paper proposes a grid index method utilizing Anti-Grain Geometry(AGG) as the engine for the map between geographic feature and image pixel. After illustrating the design and implementation of this method, it conducts experiments to compare the performance of R-tree and the proposed method. The result shows the significant performance advantage about 22% of the new method.
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Computer Engineering. 2011, 37(2): 30-33. https://doi.org/10.3969/j.issn.1000-3428.2011.02.011This paper presents a new method for partitioning space in the basis of existing space partitioning based B+tree index of moving objects, the method improves the efficiency of indexing in the situation of that moving objects are non-uniformly distributed by partitioning space using two-level grids. The paper proposes algorithms for range and kNN queries. The result of extensive experiments shows that the performance of the index is hardly impacted by the non-uniform distribution of moving objects.
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Computer Engineering. 2011, 37(2): 34-36. https://doi.org/10.3969/j.issn.1000-3428.2011.02.012Expert-chosen algorithm need process a large amount of data under complex constraints, it is a time consuming work. This paper examines the quasi-parallel approach of the algorithm. The strategies of global constraints status automatic delivering and global record locking are used to decouple the global constraints. Based on this, this paper proposes a client/server multi-threading architecture and conducts a comparative analysis for two locking methods which handles the synchronization. Experimental results show that the running speed of the optimizing algorithm is significantly improved.
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Computer Engineering. 2011, 37(2): 37-39. https://doi.org/10.3969/j.issn.1000-3428.2011.02.013According to the different characteristics of the XML and GML document, this paper parses the principle of the pull DOM and Streaming API for XML(StAX). Combining with the data characteristics of GML and the requirements of application operations, it discusses the feasibility of the mixed scheme, and presents a mixed parsing approach including pull DOM function and StAX advantage. Experimental results show that the method can parse GML document of great capacity efficiently and support complex spatial application operations during the parsing process.
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Computer Engineering. 2011, 37(2): 40-42. https://doi.org/10.3969/j.issn.1000-3428.2011.02.014Aiming at the data parameters fitting and analysis in Real-time Water Monitoring and Drought Early Warning Systems, and based on the discussion of Swing Door Trengding(SDT) and Lemple-Ziv-Welch(LZW) algorithm, this paper proposes a second compression algorithm. In the first compression, it uses average method based on SDT compression algorithm; in the second compression, it uses the modified LZW algorithm to achieve. Through testing the compression effect, simulation experimental results show that in the same hardware and software environment, the algorithm is capable of compressing data real-time and effectively.
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Computer Engineering. 2011, 37(2): 43-44. https://doi.org/10.3969/j.issn.1000-3428.2011.02.015This paper presents a thread pool size adaptive adjusting algorithm based on segmentation. User request quantity is divided into rising balancing and dropping section. This algorithm changes the size of the thread pool based on present request and thread in order to meet need of user requirement. Experimental results show that this algorithm can effectively process multiple concurrent requests, its response time is shorter compared with adjusting algorithm based average value.
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Computer Engineering. 2011, 37(2): 45-47. https://doi.org/10.3969/j.issn.1000-3428.2011.02.016On heterogeneous multi-core Cell processor, parallel programs access the irregular shared data with large time delay, and it is difficult to maintain consistency of these shared data. In order to solve the problems, this paper proposes a software Cache based on expansion of Location Consistency memory coherence protocol. Test results show that Cache can reduce data access time by nearly 40%, and improve the efficiency of parallel programs.
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Computer Engineering. 2011, 37(2): 48-51. https://doi.org/10.3969/j.issn.1000-3428.2011.02.017Because of complex relationships among SOA assets, it is hard to manage SOA asset. This paper presents a construction method for domain SOA assets repository based on Use Case Maps(UCM). It uses UCM to describe the domain demands, and translates the domain demands into the marks and the relationships among marks in the UCM model. The marks and the relationships in the UCM model are mapped to SOA assets, so that domain SOA asset repository is obtained. The method realizes effective SOA asset management and supports SOA assets reuse.
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Computer Engineering. 2011, 37(2): 52-53. https://doi.org/10.3969/j.issn.1000-3428.2011.02.018
According to the characteristics of the datasets on the sphere, the algorithm of the K-Nearest Neighbor query based on the query axis (PAM) and the algorithm of the K-Nearest Neighbor query based on the query circular planar(PCM) are presented. Theoretical research and experimental results show that both the two methods can handle the problem of the K-Nearest Neighbor query on the sphere, compared with the PCM, PAM has advantages on the memory capacitance and the query efficiency, but the expansibility of PAM is poor and PCM has high scalability.
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Computer Engineering. 2011, 37(2): 54-56. https://doi.org/10.3969/j.issn.1000-3428.2011.02.019This paper proposes a greedy approximation algorithm to solve Connected Dominating Set(CDS) problem in connected graphs. It uses ordinary heap to repeatedly select a dominating node and adds it to the tree formed by the determined nodes, so that a dominating tree for the graph is constructed. Its time complexity is analyzed in the average case by calculating the number of the heap operations. Experimental results on random network models show that compared with the existing algorithms, CDS constructed by the proposed algorithm is with smaller size.
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Computer Engineering. 2011, 37(2): 57-59. https://doi.org/10.3969/j.issn.1000-3428.2011.02.020In order to solve the problem that it is prone to occur errors when using Business Process Execution Language(BPEL) to describe complex business process, by extending synchronized Petri net, this paper designs a model named SPN-NET, which is more suitable for modeling BPEL, and translates a variety of BPEL structures into the model. A general algorithm based on similar structure is put forward. Rationality validation and performance analysis show that the model is simple, compact and comprehensible.
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Computer Engineering. 2011, 37(2): 60-62. https://doi.org/10.3969/j.issn.1000-3428.2011.02.021Most previous mining frequent closed item sets require the specification of a minimum support threshold in microarry data. However, it is difficult for users to provide an appropriate minimum support threshold in practice. Aiming at this problem, this paper presents a top-k frequent closed item set and an algorithm in microarray data. The algorithm uses top-down breadth-first search strategy to mining top-k frequent closed item set of length no less than given value min_l and pruning the search space effectively to improve the search speed. Experimental result shows that the time performance of this algorithm outperforms the CARPENTER algorithm in most cases.
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Computer Engineering. 2011, 37(2): 63-65. https://doi.org/10.3969/j.issn.1000-3428.2011.02.022
Aiming at the problem of large test cases and inefficient software test caused by test requirement change in regression test, a regression test case reduction model is proposed. This model analyzes the association between module, test requirement and test case longitudinally, analyzes association horizontally and reducts among test requirements, and then generates and reducts test cases to realize effective regression test for modified software.
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Computer Engineering. 2011, 37(2): 66-68. https://doi.org/10.3969/j.issn.1000-3428.2011.02.023Classic algorithm is slow and complex for solving the maximum module of the roots of polynomials. Aiming at these problems, this paper presents a binary search algorithm based on solving the maximum module of roots of polynomial. In the algorithm, the initialized search interval is selected by the maximum module bounds, and the theorem is used to decide whether all roots of a polynomial are in unit circle. It can obtain an arbitrary precision maximum module. Simulation results show that the algorithm has fast convergence rate and high precision.
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Computer Engineering. 2011, 37(2): 69-71. https://doi.org/10.3969/j.issn.1000-3428.2011.02.024For the application requirement of command post business, this paper defines interaction context information for human computer interaction in command space. Based on choosing the interaction context information of command post business, OWL language is used to describe the context information in command post business and the context awareness model of interaction information is built up. Semantic Web Rule Language(SWRL) rules are introduced to context reasoning on the interaction context information. So it can get richer context-semantics during the interaction in the course of operation and correspond adaptively. Through an example which is a battle scenario of division command post shows how the computer acts adaptively according to contexts of user’s location and leader’s instruction.
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Computer Engineering. 2011, 37(2): 72-74. https://doi.org/10.3969/j.issn.1000-3428.2011.02.025UML can not carry out a formal check directly to models established. In order to solve the problem, based on the static structures and dynamic behaviors of UML models, this paper proposes two kinds of methods combing Temporal Logic of Actions(TLA) for model formalization. Formal description method for translating the UML model to TLA+ is given, and TLC toolkit is used to verify TLA+ specification. An example of UML model translation and verification is given to show the effectiveness of the method.
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Computer Engineering. 2011, 37(2): 75-77. https://doi.org/10.3969/j.issn.1000-3428.2011.02.026
The disadvantages of the HF channel is that it causes a low channel utilization ratio in the HF Wireless Token Ring Protocol(WTRP) network, and it decreases the throughput during the token-ring duration. This paper proposes a modified input queuing switches model for IP gateway in this network according to the characters of HF data communication. The theoretical and simulation researches show that this input queuing switches model can solve the problem of channel resource wasting, make the high priority data to be served first and increase the throughput of the whole net.
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Computer Engineering. 2011, 37(2): 78-80. https://doi.org/10.3969/j.issn.1000-3428.2011.02.027Considering of node connectivity, remaining energy and node relative distance, this paper advances a new broadcasting algorithm that is weighted-based symmetrical area broadcasting algorithm. According to the node weights, it constructs and determines independent dominating sets, and selects candidate control node connect to independent dominating sets. And it optimizes the broadcast algorithm, eliminates some redundant forward nodes and enhances the performance of the broadcast algorithm. Theoretical analysis and simulation result show the efficiency of broadcasting time delay decreases under the situation that nodes are dense and uneven distributed.
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Computer Engineering. 2011, 37(2): 81-81. https://doi.org/10.3969/j.issn.1000-3428.2011.02.028In order to solve the problem of unfairness in current packet scheduling of Wireless Mesh Network(WSN), a Circular- Compensation-based Fair Scheduling Algorithm(CCFSA) is proposed. CCFSA works in a flow-based round-robin fashion. The packets that Mesh nodes need to send are buffered in their respective data flow queues. CCFSA ascertains channel characteristics of queues by means of channel status monitoring mechanism, and divides queue scheduling process into three periods including sending period, compensation period and dormancy period. Every period is looping execution to achieve a balanced scheduling among communication data flow and fairness enhancement of system. Simulation results prove the algorithm is effective on network throughput and fairness.
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Computer Engineering. 2011, 37(2): 85-87. https://doi.org/10.3969/j.issn.1000-3428.2011.02.029In Ad Hoc network, the unfairness of the system will affect the quality of service seriously. This paper presents a mechanism using flow unit and Weighted Fairness Queuing(WFQ) for scheduling local information, and the coordination algorithm that the exchange of node information to adjust the backoff time——Fairness Base Flow Algorithm(FBFA). The algorithm calculates every flow’s services index for each node, and exchanges with the neighbor nodes, combining with the node’s own information and neighbor node information to determine the backoff time to improve the system fairness. Because FBFA algorithm takes into account the system’s local and global fairness and throughput, experimental results show that system’s fairness index has 10%~20% increases.
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Computer Engineering. 2011, 37(2): 88-90. https://doi.org/10.3969/j.issn.1000-3428.2011.02.030
This paper derives the capacity formula of time-division half-duplex MIMO decoder-forward relay channel, and compares the performance between time-division half-duplex MIMO relay system and general cellular system by using Monte-Carlo simulation. Simulation results show that, due to the use of an appropriate relay selection algorithm, time-division half-duplex MIMO relay system is better than general cellular system in capacity, coverage. It is prominent that relay user need not use a high transmit power to obtain capacity gain.
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Computer Engineering. 2011, 37(2): 91-93. https://doi.org/10.3969/j.issn.1000-3428.2011.02.031Based on complex networks theory and Internet self-organized dynamic process, an Internet Network Model Based on Fluid and Distance(FDM) is presented. Through simulating the process of data transport in networks, the failure rate of the new model is compared with the BBV’s. The influences of the buffer capacity and the CPU velocity of hub nodes on the networks traffic are studied.
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Computer Engineering. 2011, 37(2): 94-96. https://doi.org/10.3969/j.issn.1000-3428.2011.02.032
This paper proposes an improved broadcasting mechanism and a node-maintaining algorithm based on the analysis of PeerCast broadcasting mechanism and node-maintaining algorithm. Experimental results show that the proposed scheme reduces the time of reconnection and improves the success rate of reconnection when disconnected in PeerCast. And it decreases the times of visiting YP(Yellow Page) after disconnection which reduces the stress of YP.
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Computer Engineering. 2011, 37(2): 97-99. https://doi.org/10.3969/j.issn.1000-3428.2011.02.033A Time-Of-Arrival(TOA) location algorithm based on the weighted Multidimensional Scaling(MDS) technology under the condition of line-of-sight is proposed. The location of mobile is estimated roughly using improved MDS. The impact of the topological structure of base stations to the location results is analyzed. It gets the mobile position for each group by using the improved MDS algorithms, and compares them with the rough estimation. The smaller mean square error has great contributions to final results, which is obtained by weighting the result of each group. Compared with the traditional MDS algorithms, the ability to process the redundant information is stronger with higher positioning accuracy.
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Computer Engineering. 2011, 37(2): 100-101. https://doi.org/10.3969/j.issn.1000-3428.2011.02.034
To enhance the coverage of video sensor network, this paper proposes a coverage-enhancing algorithm using Voronoi diagram based on the adjustable direction sensing model. The algorithm replaces the sector of sensing area with centroid point and constructes a Voronoi diagram by using centroid points. In order to eliminate the sensing overlapping regions and coverage holes, it makes uniform distribution of centriod points uniformly by adjusting sensing direction of nodes. Thereby it enhances the performance of the entire sensor network coverage. Simulation experiments show that the proposed algorithm can improve the coverage area and has rapid convergence.
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Computer Engineering. 2011, 37(2): 102-104. https://doi.org/10.3969/j.issn.1000-3428.2011.02.035This paper proposes broadcast schedule algorithms for request multiply data items in mobile environment, which are Based on Weight Schedule(BWS) algorithm and Weight Inverse Deadline(WID) algorithm. BWS algorithm determines weight according to data items satisfaction condition of clients, and schedules according to total weight of data items. BWS algorithm considers both using frequency of data item and satisfaction condition of clients. WID algorithm schedules according to value of total weight inverse deadline, and this algorithm considers both efficiency and urgency of broadcast. Those algorithms have better performance in data broadcast schedule.
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Computer Engineering. 2011, 37(2): 105-107. https://doi.org/10.3969/j.issn.1000-3428.2011.02.036Based on the analysis of the traditional application layer multicast tree reconstruction algorithm, combined with proactive reconstruction technique, a bottom-up application layer multicast tree reconstruction algorithm is proposed. The algorithm employs a bottom-up strategy, which combines both local and global-selection strategies for backup parent node choice. Simulation results show that the algorithm has improvement in the respect of recovery delay of multicast tree, the quality of the reconstructed tree and the control overhead of tree reconstruction.
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Computer Engineering. 2011, 37(2): 108-110. https://doi.org/10.3969/j.issn.1000-3428.2011.02.037Target coverage in Dynamic Vision Sensor Networks(DVSN) always supposes the target as a point. But the target in most situations can not be simplified as a point. The single node even does not have the ability to cover a single target. For the problem, this paper proposes a multiple node cooperation coverage algorithm. The algorithm uses the virtual potential field to make the vision node distribute uniformly around the target. It schedules the node’s work direction with the Particle Swarm Optimization(PSO) algorithm to maximize the target coverage. Simulation experimental results validate that the algorithm is effective.
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Computer Engineering. 2011, 37(2): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2011.02.038
Network performance is restricted by funnel effect of the data collection sensor networks. With the static data collection sensor networks in mind, based on spatial multiplexing and reduceing the number of hop-step principle, this paper designs construction of multi-mode-level network to achieve different levels of data packets streaming, in order to solute the sink and its few neighboring nodes bottleneck problem effectively, reaches the purpose of easing congestion and reducing transmission delay. Experimental results show that the method can reduce the communication jamming between nodes, lighten data transmitting burden of the nodes effectively, and obtains the network performance.
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Computer Engineering. 2011, 37(2): 114-116. https://doi.org/10.3969/j.issn.1000-3428.2011.02.039This paper presents an embedded system security state monitoring architecture based on multi-sensor. By the logical division of the threat grades, the design of PRI and relation to the security grades of each monitoring point, the architecture sets up the matching and handling rules of the attack behaviors and presents a data fusion based monitoring apperceive data handling model. The application instance and the performance evaluating results show that the architecture can detect and answer the various attack behaviors accurately and in time and the system’s whole security is greatly improved.
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Computer Engineering. 2011, 37(2): 117-119. https://doi.org/10.3969/j.issn.1000-3428.2011.02.040As to decrease the CPU time during detection in Snort2, this paper proposes a method based on decision tree to classify rule set aiming at avoiding needless rules construction resulted from port classification, and a better way to construct rule by information values of matching items is also adopted. Through precise timing, experimental result proves that the proposed way to construct rule set reduces detection time by 45.9% on average compared with Snort2.
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Computer Engineering. 2011, 37(2): 120-122. https://doi.org/10.3969/j.issn.1000-3428.2011.02.041Electronic Institution(EI) as a development framework is good for developing dependable distributed collaboration. However, due to its lack of information flow control mechanism, the confidentiality of information may be threatened. By extending the semantics of electronic institution, this paper designs a security model that dynamically checks information transfer. As a result, all authorized communication paths are secure. The control process of the security model is illustrated via an example. The security model can prevent unauthorized information leakage and enhance securities of EI based systems.
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Computer Engineering. 2011, 37(2): 123-125. https://doi.org/10.3969/j.issn.1000-3428.2011.02.042The key establishment protocol(called SKA) can not resist known temporary key and forward secrecy. Aiming at this problem, an efficient authenticated key agreement protocol based on signcryption is proposed. The proposed protocol uses elliptic curve cryptosystem technology under the computational Diffie-Hellman assumption, combines the long private key and short private key and implements the functions of mutual authentication and key confirmation. Analysis result proves that the efficiency and security of the proposed protocol are improved.
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Computer Engineering. 2011, 37(2): 126-128. https://doi.org/10.3969/j.issn.1000-3428.2011.02.043
Network attacker always wishes to penetrate into internal networks, direct access to more important host computers and get higher privilege on victim computers. Based on this assumption, some kinds of greedy policies are analyzed in network attack. The model is constructed and attack graph is limited under such greedy policy. Experimental results show that the attack graph is smaller in size and easier to understand than normal method without losing key attack paths.
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Computer Engineering. 2011, 37(2): 129-131. https://doi.org/10.3969/j.issn.1000-3428.2011.02.044The traditional secret sharing schemes are all based on a single dealer. However, in reality, maybe there are many applications where the shared secrets are commonly maintained by several dealers. This paper proposes a novel secret sharing scheme based on the multi-dealer by means of Homogeneous linear recursion sequence and discrete logarithm problem. In this scheme, several dealers can commonly maintain the secret and the secret can be dynamically renewed by any dealer. In the secret updated phase, the dealer just needs to publish a little public information instead of redistributing the new secret shadows. Its security is based on the security of RSA cryptosystem and the intractability of discrete logarithm problem. Verification result shows that the scheme is secure and efficient.
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Computer Engineering. 2011, 37(2): 132-135. https://doi.org/10.3969/j.issn.1000-3428.2011.02.045This paper proposes an algorithm to realize the image encryption with 1-D piece-wise chaotic symbol dynamics. Based on the principle of chaotic symbol dynamics, the position and the value of each pixel are scrambled by different chaotic sequence, which are gotten from only one short chaotic sequence. To realize the image encryption, the encryption algorithm uses the chaotic sequence to determine the algorithm of interchanging the rows, uses the primary matrix which is determined by the different chaotic sequence to scramble the positon and the value of each pixel. Experimental result shows that the algorithm is good at the image scrambling, it is can be applied into the image encryption transmission or prepocessing of secret images in digital watermark.
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Computer Engineering. 2011, 37(2): 136-138. https://doi.org/10.3969/j.issn.1000-3428.2011.02.046Aiming at the problem that vector IV of WEP and TKIP exists security risks, an encryption algorithm based on chaos and RC4 algorithm is proposed, corresponding key management is followed, while making analysis of the key space, randomicity and encryption effect. The algorithm based on chaos and RC4 algorithm uses chaos random sequence as seed key to improve the randomness of seed key, increases the difficult of deciphering, and compared with WEP and TKIP, the space of key transformation is expanded.
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Computer Engineering. 2011, 37(2): 139-140. https://doi.org/10.3969/j.issn.1000-3428.2011.02.047Aiming at the character that ARP network traffic has self-similar behavior, ARP spoofing leads ARP network traffic local burst, an ARP spoofing intrusion detection method is proposed after the theory is analyzed. The method uses Fractional Autoregressive Moving Average model(FARIMA) to forecast ARP network traffic, real-time calculates error value in every circle online between the real value and forecast value, detects the ARP spoofing by the error value. FARIMA can represent well self-similar behavior. Running results show FARIMA is advanced, and the method can effectively increase detected percentage of ARP spoofing real-time intrusion detection and can track the source host of ARP spoofing
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Computer Engineering. 2011, 37(2): 141-142. https://doi.org/10.3969/j.issn.1000-3428.2011.02.048This paper proposes a multi-secret sharing scheme, where the knowledge of Chinese remainder theorem is used. Each participant can select his own secret sharing. In the scheme, the RSA cryptosystem is used, and the system has a wide application in the cryptography field. The distributor of the system can ensure that each participant selects different secret sharing, and it is for the purpose that the secret share can progress smoothly. The security of the scheme is based on the difficulty of large integer number factorization. It is a useful multi-secret sharing scheme.
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Computer Engineering. 2011, 37(2): 143-144. https://doi.org/10.3969/j.issn.1000-3428.2011.02.049
This paper proposes a kind of adaptive blind watermark algorithm based on lifting wavelet transform. The watermark is encrypted through new arnold transform, and the original image is decomposed through lifting wavelet transform. Three high frequency coefficients of corresponding locations in the same level are sorted, and come into being a section between the maximum and the minimum which is divided into 2Q-1 sub-sections. The eigenvalue is in the different sub-zone, when the information embedded is different. The watermark can be extracted according to the locations of eigenvalue. This is a kind of blind watermark extracting method. Experimental result shows that this algorithm has a good robustness and recognizable character under many kinds of assaults.
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Computer Engineering. 2011, 37(2): 145-147. https://doi.org/10.3969/j.issn.1000-3428.2011.02.050This paper analyzes the motion characteristics of intelligent car with monocular vision, establishes the constraint mode of space and image and movement plane coordinates closely related with car’s motion control, and deduces two different mapping relationship of coordinates according to the relative position and orientation of camera. It discusses the motion control laws of car when applies them in a single target tracking and continuous target tracking, forms a visual servoing framework of eye in hand robot which has strong pertinence and practical value, and experimental results prove the validity of the laws.
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Computer Engineering. 2011, 37(2): 148-150. https://doi.org/10.3969/j.issn.1000-3428.2011.02.051
An intersection fuzzy signal control method with bus priority is presented. The buses are given a priority spatially by the bus-only lanes and the bus-priority approaches. Meanwhile, the buses are given a priority temporally by the traffic signal control algorithm with bus priority. The core module of the signal control algorithm consists of green phase module, red phase module and decision module, of which the fuzzy control strategies are designed respectively. The control target is to make bus-weighted vehicle average delay minimum. Simulation results show, compared with fixed-time control, this control strategy not only can reduce bus mean delay significantly, but also can improve social vehicles’ transit efficiency. So this control strategy can be put into practice.
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Computer Engineering. 2011, 37(2): 151-153. https://doi.org/10.3969/j.issn.1000-3428.2011.02.052null
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Computer Engineering. 2011, 37(2): 154-156. https://doi.org/10.3969/j.issn.1000-3428.2011.02.053In the task scheduling and allocation of cluster system, this paper presents a load balancing strategy based on Immune Quantum Evolutionary Algorithm(IQEA). This strategy optimizes load distribution by quantum coding and quantum evolution operator. It ensures the diversity of population by using immune operator vaccinations and immune selection when quantum is into the local extremum. Simulation result shows that this strategy has higher search efficiency than the SGALB strategy, and it can improve the whole performance of cluster system effectively.
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Computer Engineering. 2011, 37(2): 157-159. https://doi.org/10.3969/j.issn.1000-3428.2011.02.054Knowledge acquisition is a bottleneck to develop expert system. Aiming at this problem, it designs and implements a knowledge acquisition system to analyze the chemical literatures. Meanwhile, key techniques are expatiated. NLP approaches are used in this system to facilitate the automated extraction of chemical knowledge. The system segments the input text into words and assigns part of speech to each word. Tregex is used to identify the named entities on parsing trees and typed dependencies are utilized to extract qualifier for each entity. Experimental results indicate that the approaches for this task are highly efficient.
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Computer Engineering. 2011, 37(2): 160-162. https://doi.org/10.3969/j.issn.1000-3428.2011.02.055
While single service does not match the users’ requirements, automatic service composition composes several services to accommodate the users by using the semantic description of service. In multi-ontology environment, semantic heterogeneity becomes a new challenge for automatic service composition. Aiming at this problem, this paper proposes a service composition architecture based on Ontology Community(OC). The architecture converts service composition across ontologies into that in one OC with the help of ontology translation. Therefore, semantic heterogeneity is avoided. Based on this, it proposes a novel service composition algorithm using classic AI plan.
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Computer Engineering. 2011, 37(2): 163-165. https://doi.org/10.3969/j.issn.1000-3428.2011.02.056Aiming at the problems that raditional genetic encoding has low efficiency and large information loss, this paper proposes a michigan-based variable-length coding Genetic Algorithm(GA), which adopts various heuristic strategies to select genes for crossover operation. It is applied to the problem of K-anonymization. Experimental results show this method can further reduce the information loss and it is a new way to solve the problem of K-anonymization.
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Computer Engineering. 2011, 37(2): 166-168. https://doi.org/10.3969/j.issn.1000-3428.2011.02.057
This paper proposes two approximation algorithms for LCS problem of three input strings. Even if the approximation factors of the two algorithms are still 1/|?|, they can both get much better results in comparison of Gotthilf’s approximating LCS algorithm in most cases. Linear approximating LCS algorithm, takes O(n) time and O(n) space, where n is the length of the longest input sequence. It can work well in the case of large scale input strings. Recursive approximating LCS algorithm, whose time and space complexities both are O(nlogn), can receive the best precision among these algorithms at the most time. It is applicable to meet the desire of good precision for corresponding LCS problem. The two algorithms can be used to solve the LCS problem of multiple sequences and CLCS problem of multiple sequences. Experimental results prove the validity of the two algorithms.
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Computer Engineering. 2011, 37(2): 169-171. https://doi.org/10.3969/j.issn.1000-3428.2011.02.058An algorithm of decision-fusion for the speaker recognition systems is presented that uses little speech data for training models. In the phase of recognition, it decomposes the speech signal by using empirical mode decomposition processing method, extracting the speech features and repeating speech recognition based on some gained intrinsic mode function components. Meanwhile, by using this algorithm, it can fuse the results of repeat recognition and original system, and get the final output result. With the method of signal processing, repeating recognition can be implemented the original results and the accuracy rate of the recognition system based on little speech data is guaranteed. It proves the algorithm is advanced in recognition systems based on little speech data than the traditional ones by simulation experiments.
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Computer Engineering. 2011, 37(2): 175-177. https://doi.org/10.3969/j.issn.1000-3428.2011.02.060A main defect of Linear Discriminant Analysis(LDA) is that local geometric features are ignored. To address this problem, a novel manifold-based method named Locality Embedding Projection(LEP) algorithm is presented in this paper. In the algorithm, neighborhood relationship and class label information are used to classify training sample set. For each training sample, there are two classes which are called neighbor class and non-neighbor class; then inter-class scatter and intra-class scatter are defined for each training sample. The ratio of total inter-class scatter and total intra-class scatter is maximized to make nearby samples with the same class-label are more compact, and nearby classes are separated. Experimental results on ORL and FERET face databases show effectiveness of the proposed method.
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Computer Engineering. 2011, 37(2): 178-179. https://doi.org/10.3969/j.issn.1000-3428.2011.02.061
Telephone traffic load of monthly busy hour in two states of Xinjiang are predicted by the method of Support Vector Regression(SVR) combining with Differential Evolution strategy(DE-strategy). The hyper-parameter of SVR is optimized via the DE-strategy and the MAPE criteria is defined as the objective function. Telephone traffic load of monthly busy hour is forecasted by the optimized SVR, the predicted result is compared with the method of grid search and RBF neural network. A better prediction result is obtained by the generalization property of SVR combining with searching property of DE-strategy.
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Computer Engineering. 2011, 37(2): 180-182. https://doi.org/10.3969/j.issn.1000-3428.2011.02.062Considered classic CamShift algorithm used for face tracking when there being large color regions in the scene easily leading to inaccurate tracking, an improved CamShift algorithm integrating the template matching algorithm is proposed. Making the template matching successing or not in color probability distribution as iteration termination condition of CamShift algorithm can well figure out the trouble caused by color regions in face tracking. Experimental results prove the validity of the method.
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Computer Engineering. 2011, 37(2): 183-184. https://doi.org/10.3969/j.issn.1000-3428.2011.02.063
The influence of different band strategies are analyzed. A new bandwidth strategy is put forward. Through structuring an ellipse being similar with target window’s inscribes ellipse, it uses major axis and minor axis to identify bandwidth. This bandwidth strategy is integrated into Mean-Shift target tracking algorithm. Experimental results show this strategy has good effect on tracking target and reduces the time complexity.
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Computer Engineering. 2011, 37(2): 185-187. https://doi.org/10.3969/j.issn.1000-3428.2011.02.064This paper proposes Lateral and Vertical Anytime Algorithm(LVAA) to generate optimal coalition structure. It uses a branch and bound technique and pruning function to search L1, L2 and top layers of the coalition structure graph. According to the conception of the integer partition, it prunes the space horizontally, and then prunes in the remaining subspace vertically and finds the optimal coalition structure value. Experimental results show that pruning efficiency of the algorithm is high, and it can find the current optimal value at anytime.
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Computer Engineering. 2011, 37(2): 188-190. https://doi.org/10.3969/j.issn.1000-3428.2011.02.065
In FCMBP algorithm, there is no effective generation algorithm in the database of the translation equivalence classes of high-order fuzzy equivalent standard matrix in the past time, and it is very complicated to define the corresponding database of similar parameters system for each translation equivalence class of fuzzy equivalent standard matrix. In order to solve the problems, this paper proposes an automatic generation algorithm for the database of the translation equivalence classes with the low to high standard fuzzy equivalent matrix, and an algorithm for generating the corresponding database of the equivalent classes of similar parameters system. The case proves that the algorithm effectively solve the problem of automatic generation for the database of the translation equivalence classes of high-order fuzzy equivalent standard matrix.
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Computer Engineering. 2011, 37(2): 191-193. https://doi.org/10.3969/j.issn.1000-3428.2011.02.066In recognition method of RFID modulation, the main disadvantage of the back propagation algorithm of neural network commonly used lies in the slow convergence speed, the optimization procedure getting easily stacked into the minimal value locally and network parameter decided by experiment and experience. This paper designs a recognition classifier of Genetic Algorithm-Wavelet Neural Network(GA-WNN), which has global optimization capability of GA, non-linear approximation ability of wavelet and self-learning characteristic of neural network, and simulation result proves that it can improve the recognition accuracy and convergence rate.
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Computer Engineering. 2011, 37(2): 194-196. https://doi.org/10.3969/j.issn.1000-3428.2011.02.067A fuzzy matching strategy of Chinese address geocoding, in which the K-ary tree is used to enhance the accuration and search speed of matching, is proposed for given spatial database scheme. The input Chinese address is dissected and standardized as individual address elements, and each element of the address is searched against the reference database. The returned result data are saved in K-array tree, and the branch and bound algorithm is used to accelerate the matching speed, then the matched address candidate is scored using the fuzzy strategy. The Chinese geocoding strategy is applied in Hangzhou vector map data and makes some approving results.
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Computer Engineering. 2011, 37(2): 197-199. https://doi.org/10.3969/j.issn.1000-3428.2011.02.068DDBHMM(Duration Distribution Based HMM) is adopted as the acoustic model for Uyghur continuous speech recognition, and the context-dependent triphone model is selected as the best recognition unit, the Uyghur speech recognition system is optimised by using the state-binding method. In order to make the models be trained more sufficiently to improve the recognition performance, the corpus is enlarged, the emphasis is on analysis of the effect that the speech database’s enlargement brings to the recognition rate and accuracy and so on based on several groups of contrasted experiments.
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Computer Engineering. 2011, 37(2): 200-202. https://doi.org/10.3969/j.issn.1000-3428.2011.02.069This paper uses the improved shape context to recognize the complicated CAPTCHA. Through the holistic recognition method, without cutting the picture into pieces, but adopting semi-polar coordinates to model, it solves the problem that pixel points between two adhered characteristics interfered each other when modeling, designs and realizes its arithmetic method, and makes a contrast with other simple CAPTCHA’s identifying process. Experimental result shows the method put forward in this paper can recognize complicated CAPTCHA.
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Computer Engineering. 2011, 37(2): 203-204. https://doi.org/10.3969/j.issn.1000-3428.2011.02.070
By taking advantages of the characteristic of Gray code that can extend or remain the block character of binary images, this paper proposes an improved Non-symmetry and Anti-packing Model with K-lines(NAMK) representation algorithm for color images, which is called NAMKG algorithm. The description of NAMKG algorithm is presented and the storage structure and the total data amount of the algorithm are analyzed. Theoretical and experimental results show that, compared with NAMK and Linear Quadtree(LQT), NAMKG can effectively reduce the number of subpatterns and reduce the storage room.
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Computer Engineering. 2011, 37(2): 205-206. https://doi.org/10.3969/j.issn.1000-3428.2011.02.071In order to solve the problems that the existing image fusion methods have bigger Root Mean Square Error(RMSE) and smaller entropy and spatial frequency, this paper presents a multi-focus image fusion of nonseparable wavelet based on blocking. The sources images are decomposed using the nonseparable wavelet the filter bank. Then the subimages are segmented into blocks, and these blocks are fused by selecting the bigger value of the variance of the block. The inverse wavelet transform is carried out to produce the fused image. Experimental result shows that the fusion performance of the method is better than the other fusion methods. It can eliminate the blocking artifacts of the fused images and save the time of fusion.
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Computer Engineering. 2011, 37(2): 207-209. https://doi.org/10.3969/j.issn.1000-3428.2011.02.072MC craniofacial reconstruction method recovers the face skin and skull triangles in large quantities and exists impurity. Aiming at this problem, this paper uses improved Snake model to extract closed skull contour lines based on fault contour sequence. Ray method is used to accurate extract outermost layer of the skull contour. Experimental results show that the method can generate method under the condition of small craniofacial data quantity, and it can express the facial and skull form information correctly.
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Computer Engineering. 2011, 37(2): 210-212. https://doi.org/10.3969/j.issn.1000-3428.2011.02.073Aiming at the problems of large calculating scale and high complexity in Scale Invariant Feature Transform(SIFT) feature matching algorithm, this paper presents an improved SIFT feature matching algorithm based on image Radon transform. It makes d beelines on different directions in image SIFT feature point zone. Image Radon transform integral values on d beelines are adopted as SIFT feature vector descriptors, it reduces the dimensions of SIFT feature vector to improve the efficiency of feature matching. Experimental result proves that the improved algorithm has higher matching accuracy and needs less matching time, it is quite suitable for high real-time demanded system such as virtual space roaming and target identification.
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Computer Engineering. 2011, 37(2): 213-214. https://doi.org/10.3969/j.issn.1000-3428.2011.02.074
To raise the resolution of the image, this paper presents an improved Adaptive Morphologic Motion Compensation(AMMC) de-interlacing algorithm. It is based on reversibility of wavelet transform to employ the wavelet transform for the post-processing stage. It preserves the edge, and reduces the interpolation error of the motion compensation by using the spatial-temporal correlation and weighting the wavelet coefficients. Experimental results show that the algorithm can reduce the ambiguity of the image edge, and accomplish the better image quality.
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Computer Engineering. 2011, 37(2): 215-217. https://doi.org/10.3969/j.issn.1000-3428.2011.02.075
Aiming at the detection of infrared faint blob-shaped moving target under complicated background, this paper presents an image clutter suppression method based on wavelet domain Hidden Markov Tree(HMT). A wavelet-domain HMT model is used to accurately capture the dependencies across low frequency scales. It uses Bayesian criterion to estimate image background wavelet coefficients, refers to clutter suppression model to get clutter suppression image signal noise adding model. Gaussianity and independency of residual noise are also verified by using Kendall rank correlation coefficient and Friedman statistic.
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Computer Engineering. 2011, 37(2): 218-220. https://doi.org/10.3969/j.issn.1000-3428.2011.02.076Aiming at the problem that the Quick Response(QR) code by vidicon has asymmetrical beam, angulation and spin, this paper proposes the adaptive threshold method. Combinating the Roberts operator and a wavelet modulus maxima, a new edge detection algorithm overcomes the noise-sensitive defects of traditional algorithm, and accurately extracts the edge information of QR code. The QR code is located according to the principle of quadrilateral with four vertices to the diagonal line parallel of the shortest distance and the bilinear interpolation algorithm is used to correct the distorted QR code. Experimental results show that the method is reliable.
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Computer Engineering. 2011, 37(2): 221-223. https://doi.org/10.3969/j.issn.1000-3428.2011.02.077
Traditional image retrieval system has the semantic gap between image’s labeling and visual characteristic. These systems do not consider the image labeling’s latent semantic relations, and consider the personalization little. In view of these questions, this paper proposes a new personalization image recommendation method. It uses the image’s labeling semantics and vision characteristic to analyze the image, and uses the hyperbolic model to display the image. Through the multianalysis of the semantics relation in image and the original data of image, a prototype system is implemented, and this model is proved feasibility and validity.
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Computer Engineering. 2011, 37(2): 224-226. https://doi.org/10.3969/j.issn.1000-3428.2011.02.078This paper proposes a Compute Unified Device Architecture(CUDA)-based improved bilateral filtering point cloud denoising algorithm. The point cloud denoising algorithm is divided into several steps in a very high degree of parallelism. It separately designs CUDA kernel functions for each step, effectively emploies the GPU’s parallel computing power. It uses Gaussian-weighted method of calculating normal vector and effectively improves the accuracy of normal vector calculation. The bilateral denoising algorithm adds the weight of the area to alleviate the excessive smoothing. Experimental results show that the algorithm is stable and efficient, faster than the CPU calculation of multiple orders of magnitude.
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Computer Engineering. 2011, 37(2): 227-228. https://doi.org/10.3969/j.issn.1000-3428.2011.02.079
This paper researches twenty-four space forms of three-dimensional Hilbert curve primitives, and proposes a n-order three-dimensional Hilbert curve generation algorithm based on the orientation of the primitives. It puts the pixels into a space cube array, sequentially scans them and stores them based on the traversal sequence of three-dimensional Hilbert to realize image scrambling. Experimental results show that three-dimensional Hilbert curve scrambling has a stronger image scrambling degree and higher encryption security compared with the two-dimensional Hilbert curve.
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Computer Engineering. 2011, 37(2): 229-231. https://doi.org/10.3969/j.issn.1000-3428.2011.02.080Aiming at the fusion of Near Field Communication(NFC) technology and 3G smart card technology, this paper proposes smart card system with multi-function. It introduces the link and transmission technology of NFC communication and 3G smart card technology-related contents, further studies the fusion method. Adopting NFC technology and USIM card as a carrier, the system uses contactless application functions in USIM card. According to the the fusion system model and design scheme, analyzing results show that the system has good fusion performance.
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Computer Engineering. 2011, 37(2): 232-234. https://doi.org/10.3969/j.issn.1000-3428.2011.02.081Aiming at the equipment operation safety problem of railway station, this paper introduces a wireless monitoring system based on wireless T-R chip nRF905 and main processing chip Atmega16. This system adopts modularization design which includes signal collecting, wireless data transmission and signal processing based on PC software. The slave computer returns collected signal to host computer after receiving control command from PC software, and the monitoring system is achieved after the signal is processed and displayed by the PC software. The trial operation on railway station demonstrates its stability and accuracy.
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Computer Engineering. 2011, 37(2): 235-237. https://doi.org/10.3969/j.issn.1000-3428.2011.02.082This paper designs a Hardware In the Loop(HIL) simulation platform for mini airship autopilot, which includes building a validation machine for flight control system based on embedded systems ARM9 and navigation and control module using hierarchical structure, building a mini airship dynamics, pressure-controlled system and the sensor signal simulation model and so on. It brings HIL simulation test system’s hardware and software combination into full play, shortens development cycles and improves system reliability. Simulation results show the effectiveness of the platform.
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Computer Engineering. 2011, 37(2): 238-239. https://doi.org/10.3969/j.issn.1000-3428.2011.02.083
The promotion of efficiency of transporting system is significant to the Semiconductor Wafer Fabrication System(SWFS). To reduce the average traveling time, the average waiting time, and blockages in the Interbay system, this paper proposes a new real-time method using Hungarian algorithm. Simulation results based on data of 300 mm wafer fabrication systems show that this method outperforms the traditional schedule approaches in term of overall efficiency and performance of Interbay material handling system.
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Computer Engineering. 2011, 37(2): 240-241. https://doi.org/10.3969/j.issn.1000-3428.2011.02.084
WSRF specification is introduced. The WSRF-based architecture for remote experiments is designed by combining the features of FPGA experiments and the state management of WSRF protocol. The resource services of FPGA experiments are designed and implemented by using WSRF.NET, and the correctness of the service is verified by experiments. The result of verification experiments shows that the resource services of FPGA experiments, which are designed by using the WSRF specification, solve the middle state issue of the experiments, and free the time and space of experiments.
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Computer Engineering. 2011, 37(2): 242-244. https://doi.org/10.3969/j.issn.1000-3428.2011.02.085Because the proposed reconfigurable resource models are difficult to be implemented or can not make full use of the resource, a new resource model is proposed. Based on the model, a hybrid real-time schedule algorithm is proposed to schedule periodic and aperiodic tasks. The algorithm partitions periodic tasks into several groups and reserves one slot on FPGA for each group. When an aperiodic task arrives, the algorithm pre-schedules all the periodic tasks’ instances in current busy period and schedules the aperiodic task guaranteeing the deadlines of periodic tasks in current busy period and without influences on the tasks’ execution in the next busy period. Experimental results demonstrate that the algorithm can make full use of reconfigurable resource and meet all accepted tasks’ deadlines.
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Computer Engineering. 2011, 37(2): 245-247. https://doi.org/10.3969/j.issn.1000-3428.2011.02.086In order to make level of the incoming symbols approach the reference constellations, an improved Digital Automatic Gain Control (DAGC) algorithm for DVB-S2 system is proposed to enable better demodulator performance. Compared with traditional algorithm, it possesses many advantages, such as supporting much low signal-to-noise ratio and compatible of both with pilot and without pilot modes as well as much lower complexity.
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Computer Engineering. 2011, 37(2): 248-250. https://doi.org/10.3969/j.issn.1000-3428.2011.02.087A multi-goal optimization model for Overlay Link Selection Problem(OLSP) is proposed based on the consideration of all factors influencing on Overlay network performance. It aims at achieving the best routing performance and the least IP link overlap degree with the least maintaining costs. Pareto optimality theory and Immune Clone Algorithm(ICA) are adopted to solve this problem and the digital simulation experimental result shows the availability of this model and the convergence of ICA .
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Computer Engineering. 2011, 37(2): 251-252. https://doi.org/10.3969/j.issn.1000-3428.2011.02.088
BIOS Rootkit is difficult to detect. Aiming at the problem, this paper proposes a behavior characteristics-based BIOS Rootkits detection method. By studying the BIOS Rootkits’ principles and key technologies, this method generalizes, defines and formally describes the behavior characteristics of BIOS Rootkit. Behaviors information is got in decompile phases, and the malicious level is judged according to the rate of a complete BIOS Rootkit formed by those behaviors. Experimental results prove that the method is effective to detect BIOS Rootkits.
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Computer Engineering. 2011, 37(2): 253-255. https://doi.org/10.3969/j.issn.1000-3428.2011.02.089The former evaluation method makes more use of hardware-based, software as a supplement, the cost of test is high, and information is monotonous. This paper is based on the case with combinations of virtual instrument hardware module structure for the establishment of the evaluation Petri net model, generates test cases by software for test in order to achieve software-based and hardware-supplemented evaluation mechanism. Tests show that this method not only facilitates the generation of test cases, reduces the cost of test and is effective, but also can draw on universal design in the virtual instrument hardware evaluation system.
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Computer Engineering. 2011, 37(2): 256-257. https://doi.org/10.3969/j.issn.1000-3428.2011.02.090
The transplantion of operating system for the wireless sensor networks is to modify the hardware-irrelevant layer which makes it work on the different hardware platforms. On this issue, based on the analysis of the structure and hardware-abstract hierarchical on TinyOS 2.0, this paper expatiates how to implement the transplantion on the SoC-based and low-power CC2430 platform and tests the function of the modules. Test results show that the transplanted module works correctly, which lays a solid foundation for the future work.
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Computer Engineering. 2011, 37(2): 258-260. https://doi.org/10.3969/j.issn.1000-3428.2011.02.091Frame synchronization is the basis of DVB-S2 demodulation. With the comprehensive study and comparison of the existing methods, this paper presents an improved frame synchronization scheme for DVB-S2 system based on pilot symbols correlation and double-peak detection. The proposed scheme reduces the false synchronization probability significantly with relatively lower computational complexity in contrast to the existing methods, which is evaluated by extensive experiments. In addition, it can acquire frame synchronization rapidly and correctly even under the worst channel condition specified by DVB-S2 standard (5 MHz frequency offset and -2.35 dB signal-to-noise ratio).
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Computer Engineering. 2011, 37(2): 261-262. https://doi.org/10.3969/j.issn.1000-3428.2011.02.092
Agent-oriented scene simulation developing technology based on XML is proposed. Behaviors of simulation entities are described in an Agent-oriented approach, which are stored in an XML file. In this way, the description and control of simulation entities are separated from the simulation software. By applying this method to the deep submergence rescue and life-saving scene simulation, the efficiency of developing a scene simulation system is improved.
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Computer Engineering. 2011, 37(2): 263-265. https://doi.org/10.3969/j.issn.1000-3428.2011.02.093This paper describes the design and implementation of the data dampling and drocessing system of EUV camera, using XC2V3000 as main processor, AD1671 as the analog-to-digital converter. The system implements functions such as acquisition of original data of the camera, rectification of the original data, conversion to image data, and data buffering. In order to enhance the resistance against single event effect, long line shift-registers are avoided. Tag data are inserted between valid data, instead of the delay of control signals with shift-registers. Stability of the system can be improved.
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Computer Engineering. 2011, 37(2): 266-268. https://doi.org/10.3969/j.issn.1000-3428.2011.02.094Aiming at the defect that Build-In Self-Test(BIST) is difficult to detect the anti-random test fault, this paper presents a method to make full use of don’t care bits of test vectors to increase the length of test groups. The response vectors of interior nodes are generated from a given circuit and its test vectors which include don’t care bits. Directed graphs are built based on some heuristic rules and a longest public path is found by using depth-first search algorithm. Experimental results on the benchmark circuits demonstrate that the number of vectors in the largest test groups increase by an average of 2.2.
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Computer Engineering. 2011, 37(2): 269-271. https://doi.org/10.3969/j.issn.1000-3428.2011.02.095The Flexible Job-shop Scheduling Problem(FJSP) is a generalization of the classical Job-shop Scheduling Problem(JSP). In this paper, a multi-Agent negotiation and scheduling strategy based on biding is proposed. This study focuses on bid calculation. The system contains part Agent and machine Agent. Through biding part Agent selects the appropriate machine and machine Agent selects the appropriate part by competing with others based on market mechanism to maximize its income and use dispatching rules to schedule the parts. The system is implemented in Java and the proposed algorithm is tested on a standard instance taken from the literature and compared with other approaches. Experimental results show the effectiveness of the negotiation function.
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Computer Engineering. 2011, 37(2): 272-274. https://doi.org/10.3969/j.issn.1000-3428.2011.02.096In the Decision Support System(DSS) of city storm surges, there exists many Web Services which are called by users as data interfaces or functions, the management and real monitoring for this Web Services is a burning question. This paper builts a management and monitoring platform which is based on B/S for this Web Services using the technology of Web Services and Flex, the business logic of this system is handled by Web Services and Java, which is used for support of data, in the other hand, the Flex is used for the presentation of the Web pages. Run effect of the system shows that the system can display effectively to Web Services and add, delete, update and select, the information of CPU and memory utilization rate can be obtained effectively and the monitoring for these hosts is valid.
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Computer Engineering. 2011, 37(2): 275-277. https://doi.org/10.3969/j.issn.1000-3428.2011.02.097On the basis of the structure of the Serial Interference Cancellation(SIC), this paper proposes a multi-user detection algorithm based on power-grouping of partial parallel soft interference cancellation. In the algorithm, users are divided into groups according to their power, parallel soft interference cancellation is used in the same groups and serial interference cancellation in different groups to detect the groups of users in turn by which the complexity of parallel interference cancellation is reduced. Theory analysis and simulation results show that the performance of the algorithm is better than other parallel interference cancellation algorithms and improves the system capacity.
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Computer Engineering. 2011, 37(2): 278-280. https://doi.org/10.3969/j.issn.1000-3428.2011.02.098
This paper represents the background and the significance of video abstraction technology, as well as the three types of research method for video abbreviation. A research method is proposed for video abstraction based on local-space model. In the model, the key frame is got by the analysis of the intra-frame and inter-frame video sequence information, and these key frames are extracted to construct the video segment by double-interpolation. With the DES in the DirectShow software, the video segments are edited and fused into a final dynamic video abstraction. Experimental results show that the video abstraction is generated automatically without any article intervention, which contains the main information of the video but little redundant information.
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Computer Engineering. 2011, 37(2): 281-283. https://doi.org/10.3969/j.issn.1000-3428.2011.02.099To solve the problem of the picture distorted that is caused when the picture is projected to semispheric screen, this paper presents a method about semispheric screen geometry correction and camera calibration. The method finds out the corresponding relations and computational method between 3D semispheric space and 2D projector space, builds the mathematical model of semisperic screen projective space. It obtains the predeformation grid by back projecting the ideal grid demarcated on the semispheric screen to projector space, makes the geometry transformation between predeformation grid and prespective grid by Singular Value Decomposition(SVD), calibrates the camera by control points fitting. A multi-touch system platform based on semispheric screen is implemented, experimental result shows that the method achieves expected object.
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Computer Engineering. 2011, 37(2): 284-285. https://doi.org/10.3969/j.issn.1000-3428.2011.02.100
Aiming at the conflict between the RAM access and the design performance, in the four layer C-to-VHDL reconfigurable compiling framework which is based on Low Level Virtual Machine(LLVM) framework, this paper proposes an optimization algorithm for RAM access. By analyzing the load and store instruction in LLVM’s IR and the data dependence, it creats a dedicated data path to optimize the process of reading and writing to RAM. Experimental results show that the optimized algorithm can effectively reduce the access number to RAM.
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Computer Engineering. 2011, 37(2): 286-289. https://doi.org/10.3969/j.issn.1000-3428.2011.02.101In order to overcome the high Peak to Average Power Ratio(PAPR) of Orthogonal Frequency Division Multiplexing(OFDM) signal, a construction method of multi-phase orthogonal matrix family is proposed and its nature is analyzed, two kinds of low-PAPR and data security guaranteed algorithms of OFDM are designed by using multi-phase orthogonal matrix. Theoretical analysis and simulation results show that the matrix number of orthogonal matrix family is , and the PAPR can be reduced without introducing error rate, the data security is guaranteed through taking any matrix as a key and multiplying the OFDM input signals. In addition, the PAPR of system can be well improved by combining this pre-coding method with Partial Transmit Sequence(PTS) technology.
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Computer Engineering. 2011, 37(2): 290-292. https://doi.org/10.3969/j.issn.1000-3428.2011.02.102This paper analyzes the shortcomings of existing meter reading systems, proposes a wireless centralized meter reading system based on short distance wireless communication and 3G. The system combines the short distance wireless communication and 3G technology together with the data’s collection and transmission through a wireless manner. The collected data of meter are transmitted through the 3G network to the billing department of the data management center. When compared with existing meter reading systems, this system has a more flexible layout, larger coverage, lower power consumption , higher real-time features, less interference and gets better results in practical application.
Volume 50 No 4
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