05 September 2007, Volume 33 Issue 17
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Computer Engineering. 2007, 33(17): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2007.17.001This paper proposes a new virtual MIMO architecture, based on a model of wireless senor network. The proposed scheme does not needreceiver-side cooperation and decreases the complexity of receiver-side cooperation in previously proposed virtual MIMO schemes. From the viewof the lifetime of all the networks, the conclusion that MIMO need less energy than SISO in the same situation is analyzed and deduced. In addition,the effect on energy caused by the channel evaluation based on the pilot is calculated. The results of simulation show this solution agrees with thetheory analysis
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Computer Engineering. 2007, 33(17): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2007.17.002In wireless sensor networks, sensor location plays a critical role in many application. In the past, a number of location discovery schema have been proposed. KPS has an advantage because anchor nodes and distance/angle measurement among nodes are not involved, but high inaccuracy as compared to others. This paper proposes a new location algorithm to improve the inaccuracy of KPS, and conducts simulations to evaluate the scheme.
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Computer Engineering. 2007, 33(17): 7-9. https://doi.org/10.3969/j.issn.1000-3428.2007.17.003The composition and decomposition of the data base is an important problem in practice application, and its mathematic model is the composition and decomposition of the information systems. By giving definition of object composed information systems, attribute composed information systems, sub-object information systems and sub-attribute information systems, this paper discusses the attribute character relationships between the combined information systems and the original information systems, sub-information systems and the original information systems, respectively.
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Computer Engineering. 2007, 33(17): 10-12. https://doi.org/10.3969/j.issn.1000-3428.2007.17.004The paper studies the component repository technology based on semantic retrieval. The component semantic description and retrieval can be achieved by semantic reasoning and matchmaking. So, the system can find the component that can not be query out in the traditional ways. It can be taken as a reference model to build semantic-oriented component repository.
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Computer Engineering. 2007, 33(17): 13-16. https://doi.org/10.3969/j.issn.1000-3428.2007.17.005This paper presents a new Petri nets model named standard properly end Petri nets. It is proved that the language descriptive ability of standard properly end Petri nets is equal to regular expression. This paper reaches the quality about standard properly end Petri nets operation such as connection, union, kleene closure and concurrence. As essential supplement of formal language theory, the transformation methods from the regular expression with concurrence operation to standard properly end Petri nets is given. The methods from the regular expression to standard properly end Petri nets is given.
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Computer Engineering. 2007, 33(17): 17-19. https://doi.org/10.3969/j.issn.1000-3428.2007.17.006Quadratic generator is a kind of widely used pseudorandom number generator. This paper studies the cryptanalysis of the quadratic generator. It shows given the shift b, modular p and sufficiently many of the most significant bits of several sets of the form un, un1, un2, how to disclose the multiplier a and the initial value u0, if un does not lie in a small set, where un,un1,un2 are outputs of the quadratic generator. Then it shows that given the modular p and sufficiently many of the most significant bits of several sets of the form un, un1, un2, un3, one may disclose the a, b and the initial value u0 if un does not lie in another small set. The results of this paper show that it should be careful when quadratic generator is used in a cryptosystem
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Computer Engineering. 2007, 33(17): 20-22,2. https://doi.org/10.3969/j.issn.1000-3428.2007.17.007With the increase of network bandwidth, high performance protocol processing has shown its importance in network systems. Experimental results show that some advances in computer architecture, such as faster processors and larger cache, are not enough for TCP/IP processing. This paper presents a formal analysis on I-cache behavior of batch protocol processing. It is proved that achieving the optimal I-cache behavior is an NP-hard problem, suggests an off-line scheduling method and gives an analysis of its impact on performance.
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Computer Engineering. 2007, 33(17): 23-25. https://doi.org/10.3969/j.issn.1000-3428.2007.17.008The paper presents a kernel based prediction modeling method for nonlinear time series. Phase space of time series is reconstructed to get its embedding dimension, and a method of phase space reconstruction based on kernel principal component analysis(KPCA) is proposed. A weighted support vector regression(SVR) is adopted to set up prediction model according to the characteristics of time series. The experimental results on different benchmark data show that the model based on the proposed method has higher accuracy compared with normal SVR model, proving the efficiency of the method for nonlinear time series prediction modeling.
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Computer Engineering. 2007, 33(17): 26-28. https://doi.org/10.3969/j.issn.1000-3428.2007.17.009Worm attacks are threatening today’s Internet security. Vaccination has become an effective means for combating Internet worm. This paper proposes an agent-oriented worm defense system by which the agents collaborate with each other to defend against Internet worms. Some agents travel in the network and distribute vaccine to every host. It researches the migration mechanism of agents and the deployment algorithm of vaccine repository nodes. By this way, vaccine distribution path is optimized and distributing time is shortened.
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Computer Engineering. 2007, 33(17): 29-30,3. https://doi.org/10.3969/j.issn.1000-3428.2007.17.010The characteristic of airport in the SAR image is analyzed here and a new method for airport extraction from SAR image is created. In the process of the extraction of the new method, it takes the advantage of the knowledge of the feeble back wave of the airport surface. And it improves the fuzzy C-Means(FCM) clustering and uses the improved clustering to segment the airport. It extracts the airport by means of the Hough transform and region growing. Lastly it defines the contrast of gray scale of region(CGSR) and utilizes the knowledge of high value of CGSR between the airport and the circumference of the airport to remove the noise in the extracted airport. It is proved by the tests that the new method given here can well extract the airport and meet the requirements of the airport extraction.
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Computer Engineering. 2007, 33(17): 31-33,4. https://doi.org/10.3969/j.issn.1000-3428.2007.17.011
10-gigabit Ethernet MAC uses 64bits data path and 156.25MHz frequency to meet the bandwidth of 10Gb/s. The wider data path and the higher frequency bring new challenges to the implementation of 10-gigabit Ethernet MAC controller. These challenges include getting data boundary, CRC encode/check, high frequency logic design and compliant with 1-gigabit Ethernet. This paper proposes some solutions, which are auxiliary counter, cross pipeline CRC, deep pipeline and asynchrony RAM. It also designs a 10-gigabit Ethernet MAC controller by using these solutions. The post place and route simulation result of this controller indicates these solutions are correct and feasible.
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Computer Engineering. 2007, 33(17): 34-36. https://doi.org/10.3969/j.issn.1000-3428.2007.17.012The border gateway protocol(BGP) is vulnerable to various attacks for previous design limitations. However, the heavy and complicated public key infrastructure (PKI) key management and too much storage space cost in current BGP path verification mechanisms severely block BGP security solutions from being implemented and deployed in real world. For the first time the ID-based signature scheme is introduced into BGP path verification, and so the ID-based path verification mechanism(IDPV) is proposed. Compared with current certificate-based path verification mechanisms, IDPV effectively simplifies PKI key management and reduces router’s storage space cost, improves path verification performance. The BGP secure solution with IDPV will be more easily realized and deployed in Internet.
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Computer Engineering. 2007, 33(17): 37-39. https://doi.org/10.3969/j.issn.1000-3428.2007.17.013Aiming at the deficiencies of current mutation algorithm based on artificial immune system, such as fault positive is high and the efficiency is very low, an improved evolution optimization with mutation algorithm is proposed. This new algorithm introduces evolution operator into the mutation rule during the cells mutation process to improve the detection efficiency and to overcome the shortcoming of the local optimum. And the concepts and formal definitions of self/non-self are given, mature-lymphocyte lifecycle, and affinity accumulation process are presented. Experimental results show that when the k set about 40 with the parameter adapted, the TP value can be stabilized on 95％. And the algorithm greatly enhances the response rate and precision of detection and the proposed model has the features of real-time processing, self-adaptively, thus providing a promising solution for intrusion detection.
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Computer Engineering. 2007, 33(17): 40-42. https://doi.org/10.3969/j.issn.1000-3428.2007.17.014This paper analyzes desires of dynamic group key managerment oriented to vitual organization in grid computing system, investigates the four layers architecture of the VO based on selective environment by members in VO and the policy of member admission, and gives a layered distributed key protocol which appropriate to the VO of four layers architecture, the protocol can avoid the abuse of the centralized distribution and the single-point failure exists in the management pattern, also possesses the benefit of layered architecture.
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Computer Engineering. 2007, 33(17): 43-45. https://doi.org/10.3969/j.issn.1000-3428.2007.17.015This paper discusses problem of stock pattern dependency mining on data streams, proposes a mining algorithm. This algorithm includes pre-process steps such as time series segmentation and pattern presentation, using 4 item rule tuples to present the dependency and to calculate the confidence and support degree, and the synopsis structure for two and N data streams. Experiments on stock price data and a real system show that the algorithm is effective and can be used in forecasting.
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Computer Engineering. 2007, 33(17): 46-48. https://doi.org/10.3969/j.issn.1000-3428.2007.17.016When two-class problem samples are very unbalanced, SVM has a poor performance. A novel SVM algorithm, DFP-SVM is presented to solve the problem implemented by transfering the quadratic program with limited condition into quadratic program without constraining condition. Optimal computation is conducted to achieve exciting results. In order to overcome the problems of traditional snake associated with poor convergence to boundary concavities and sensitive initialization, gradient vector flow based on deformable models is presented to segment tumor region. And three new moments based on boundary are also developed. The novel classifier applies the three moments and other shape features to classify the tumor into the malignant or the benign. Computational results indicate that the modified algorithm has a strong capability of classification for the unbalanced data of small set of samples related to two-class problems.
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Computer Engineering. 2007, 33(17): 49-50,5. https://doi.org/10.3969/j.issn.1000-3428.2007.17.017The analysis of underwater acoustic image object of sonar is a key issue in autonomous underwater vehicle(AUV). By applying Radon transform, a new method for underwater acoustic image’s feature extraction and classification is proposed, which is non-sensitive to the ambiguous noise. After getting the close edge by morphological edge extraction and thinning operators, this paper constructs the edge moment invariants based on Radon projection and uses them in classification of three kinds of underwater objects. Simulation results show the proposed method is robust and its effectiveness is better than Hu’s moment invariant and object’s plane moment invariance in Radon projective space according to the computing speed.
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Computer Engineering. 2007, 33(17): 51-53. https://doi.org/10.3969/j.issn.1000-3428.2007.17.018When nodes are organized as clusters, data packets can be transmitted from cluster members to head in either single hop or multi-hop communication mode. Using maximum energy dissipation of cluster members as evaluation criterion, this paper researches energy efficiency of these two modes. It comes to the conclusion that the optimal communication mode depends on channel path loss. Take the uneven energy consumption caused by solely single hop or multi-hop mode into consideration, a hybrid communication mode that nodes alternate between single hop and multi-hop mode with certain probability is proposed. The simulation result verifies that hybrid mode provides the best energy efficiency as well as even energy dissipation.
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Computer Engineering. 2007, 33(17): 54-56. https://doi.org/10.3969/j.issn.1000-3428.2007.17.019Based on the analysis of Paik’s Hopfield network for image restoration, this paper presents a modified full parallel self-feedback continuous Hopfield network model to restore degraded image. And by introducing a calculated parameter γ rather than γ obtained by experiments or experience, the modified network converge can be made faster . The result of the model in restoring blurred image is compared with that of J.K. Paik’s method, which shows the method makes the restoration process faster and output better restoration quality. In experiment 2, compared with the constant parameter, it testifies that the calculated parameter γ can give better convergence rate for the network.
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Computer Engineering. 2007, 33(17): 57-59,6. https://doi.org/10.3969/j.issn.1000-3428.2007.17.020This paper analyzes algorithm of Espresso. Based on judging macrocosm, it presents an algorithm of identification about multi-input multi-output logic functions essential primes and complete redundancies and relative redundancies. It calculates cofactor of multi-input multi-output logic functions to judge macrocosm, identifies essential primes and complete redundancies and relative redundancies according by result of judging macrocosm, then forms club of essential primes and complete redundancies and relative redundancies. It completes optimization identification software design of multi-input multi-output logic functions about two-level SOP. It is confined that the max-input variables are 128, the max-output variables are 256, the sum of max-input-output variables are 300, the max-input products are 20 000, and it successfully overpasses testing of Benchmark based on computer of Pentium 1.8GHz and 512MB memory.
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Computer Engineering. 2007, 33(17): 60-62. https://doi.org/10.3969/j.issn.1000-3428.2007.17.021The application of design of experiments for software test has developed to the age of combinatorial test, an important issue of which is in what degree parameters interaction is required to be covered. A systemic method to analyzing the amount of parameters resulting in software failures is presented. In the method, failure rules of software under test can be got from the relationship between failures and the parameters’ number of similar software or applications in the same field. Consequently, the level of parameters combination which should be covered by combinatorial test data set can be defined. By using it, combinatorial test method can generate more effective test data.
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Computer Engineering. 2007, 33(17): 63-65,6. https://doi.org/10.3969/j.issn.1000-3428.2007.17.022A bill of software component (BOSC) of component-based development (CBD) is constructed in the paper according to application domain and software architecture focused on in CBD, based on which an algorithm to create characteristic-oriented BOSC is proposed as a management solution of software component reuse. In software lifecycle, BOSC figures structure of software product of CBD, supports software maintenance and update. The application of BOSC shows that the solution can improve development efficiency and project management effectively.
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Computer Engineering. 2007, 33(17): 66-68. https://doi.org/10.3969/j.issn.1000-3428.2007.17.023The technology of software reuse is the key way solving the crisis of software. This paper adopts the homomorphism reuse in the phases of lifetime cycles in software development from code to component to architecture and the system of software development based homomorphism is provided. The system not only includes the usual way of software development but also includes the homomorphism reuse. In the meantime, a demo of Web design based on homomorphism reuse is developed for the system.
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Computer Engineering. 2007, 33(17): 69-70,8. https://doi.org/10.3969/j.issn.1000-3428.2007.17.024There are rich information resources in the railway freight invoice. It is important and basic data for the prosecution and management of the railway production. This paper from the three aspects knowledge excavates the freight invoice. The characteristic relative model is developed and the characteristic rule knowledge expression is abstracted by applying set theory. It presents the algorithms, knowledge excavates the practical freight invoice and analyzes the inspiration of marketing; applies the clustering to knowledge excavate the model and does research for the subdivision of goods transportation market from such aspects as the transportation distance, the sort of goods, the number of price for goods transportation and the clients’ incoming contributions to the corporation etc. The knowledge from excavating has specified the choice of object markets for the railway goods transportation. The freight invoice data is handled by ARIMA method to be seasonal knowledge excavated. The freight amount in 2006 is evaluated according to the historical data from 1999 to 2005.
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Computer Engineering. 2007, 33(17): 71-73,7. https://doi.org/10.3969/j.issn.1000-3428.2007.17.025With the popularity of multiprocessor embedded system, like many other embedded operating systems, RTEMS, as a great open source embedded operating system, also supports parallelization. However, RTEMS’s multiprocessor support may cause deadlock on multiprocessor system. And it may cause severe performance damage to the hardware when distributing data in data processing system. Based on an onboard computer research, this article improves RTEMS’s multiprocessor support and will work out an optimization for RTEMS’s performance bottleneck that may occur in data distribution.
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Computer Engineering. 2007, 33(17): 74-76. https://doi.org/10.3969/j.issn.1000-3428.2007.17.026Most outlier detection approaches suffer from parameter dependencies and parameter instability. In order to solve the two problems, this paper introduces a new notion of outlier based on reachable neighbor, which is called RN-Outlier, and proposes novel and fast algorithms for outlier detection. Experimental results of synthetic datasets and real datasets show that the algorithm outperforms both LOF and LSC methods. The algorithm is more stable when parameter changes.
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Computer Engineering. 2007, 33(17): 77-79,8. https://doi.org/10.3969/j.issn.1000-3428.2007.17.027This paper proposes the preemptive scheduling strategy, EF-RM for wireless sensor network operating system. EF-RM can archive the task scheduling for periodical task and un-periodical task. By using the EF-RM scheduling strategy, the important task can be executed with high priority. When a wireless sensor node is idle, the EF-RM can bring the node into sleep mode to save the energy. The scheduling strategy is achieved in the TinyOS. And the experiment shows that EF-RM scheduling strategy can improve the response of the wireless sensor nodes in heavy load with a little cost of energy.
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Computer Engineering. 2007, 33(17): 80-82. https://doi.org/10.3969/j.issn.1000-3428.2007.17.028
WebLog mining is application of sequential pattern mining of data mining technology on Web server log files. Sequential patterns mined from Web logs are used to improve the quality of information service on Web. The main challenge of mining access sequential pattern form WebLog is the high processing cost due to the large amount of data. By combining SPAM and PrefixSpan, this paper proposes a new arithmetic SPAM-FPT. By constructing first_positon_table, SPAM-fPT avoids “joining” or “ANDing” in SPAM and generating a large number of projected database in PrefixSpan, and gets all the frequent sequential patterns form dtatabase.
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Computer Engineering. 2007, 33(17): 83-85. https://doi.org/10.3969/j.issn.1000-3428.2007.17.029To analyze traditional Web services discovery mechanism, service recall ratio is discovered and precision ratio is very low. To improve the service match arithmetic in Web services discovery, this paper presents a semantics-based Web services secondary match algorithm. The algorithm makes services match based on keyword technology and semantic relationship at conceptual level, and chooses the best service according to match degree. The algorithm improves the efficiency of match services and achieves a flexible service discovery mechanism. It is flexible and extensible to accomplish complex Web service requests.
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Computer Engineering. 2007, 33(17): 86-89. https://doi.org/10.3969/j.issn.1000-3428.2007.17.030The problem of inference rules for multivalued dependency is the key to solve implication problem between dependencies in XML and the key problem of XML normalization theory. In this paper, the definition of XML tree and tree tuples etc. are given in a new way. Different from Vincent, the concept of multivalued dependency for XML based on DTD is given. The definitions of closure, path dependency basis and the closure of paths of multivalued dependencies for XML are also proposed. A sound and complete set of inference rules is presented, and soundness and completeness of the inference rules are proved.
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Computer Engineering. 2007, 33(17): 90-92,9. https://doi.org/10.3969/j.issn.1000-3428.2007.17.031Along with the quick development in every fields of embedded system, the porting technology of embedded operating system has become an important problem of embedded development. This paper investigates the theory and technology of porting embedded operating system to different hardware flats, and advances a scheme which can be used to port embedded operating system with the means of blocking and layered. This scheme is applied to the project of porting CRTOSII to the board which integrates the chip of S3C2410. It proves the validity and feasibility of the scheme.
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Computer Engineering. 2007, 33(17): 93-95. https://doi.org/10.3969/j.issn.1000-3428.2007.17.032A Delaunay triangulation algorithm based on optimal convex hull technology is presented. The algorithm makes the discrete points sort in scan manner, and secondly it constructs convex hull and triangulates the sorted points by the optimal convex hull technology which is proved by the author, and optimizes triangles utilizing topological structures of directed edges. The algorithm avoids the test of point of intersection. Moreover, the average test times of a newly added point is under 4, so that the high efficiency of triangulation can be sure.
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Computer Engineering. 2007, 33(17): 96-98,1. https://doi.org/10.3969/j.issn.1000-3428.2007.17.033A method to decide the non-reachability of a marking using S-invariants is provided by Hohn F E; In fact, there exists some markings, the non-decidability of which can not be decided with S-invariants. But it can be decided with modular-n S-invariants. Desel J points it out in reference two. However, whether or not there exists some modular-n S-invariant, which can be used to decide the non-reachability property of a marking? And if such modular-n S-invariant exists, how to find it? There is no answer to both of the questions. The definition of effective modular-n S-invarients is given, and both of the problems can be solved with effective modular-n S-invarients. Furthermore, a method to find the effective modular-n S-invarients using the matrix integral decomposition is presented.
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Computer Engineering. 2007, 33(17): 99-101. https://doi.org/10.3969/j.issn.1000-3428.2007.17.034Partitioned workload system (PWS) is one job management system using partition and dynamic resources-lease technology, which enhances the manageability of JMS and improves the utilization of cluster system. With optimized communication system, PWS can support cluster systems with thousands of CPUs or nodes. PWS has been applied in Shuguang 4000A super server and other computation fields requiring high performances. the design and implementation of the PWS is introduced.
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Computer Engineering. 2007, 33(17): 102-104,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.035This paper reviews the current research status of time series similarity search, and proposes ordinal-transformation-based similarity search method, which can achieve fast trend similarity search among sub-series of different length. In addition to insensitivity to horizontal shifting and time-axis scaling, the proposed method has a lower false alarm ratio and a higher indexing efficiency. Experimental results show the proposed method is quite competitive in terms of speed and robustness.
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Computer Engineering. 2007, 33(17): 105-107,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.036This paper proposes a new agile methodology——FXP for small and medium sized software vendor, by investigating the development of some agile methodology like XP, FDD. Meanwhile, practice is made successfully to approve the validity of FXP. FXP integrates the methodology of "heavyweight" software process with the practice of agile software process based on XP theory. By the time it emphasizes collaboration conformability of "heavyweight" software process, it brings in the merit of "lightweight" agile software process, i.e. high efficiency in communication and share. It effectively integrates the dimensions of project management, software engineering, quality assurance into one cooperative environment. It narrows the gaps of three layers among schedule track, requirement track and quality track.
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Computer Engineering. 2007, 33(17): 108-110. https://doi.org/10.3969/j.issn.1000-3428.2007.17.037For the full use of database resources, this article studies the method of the “main memory” realization of the data distribution and the exchange in the distributional isomerism database. The method uses the cross platform characteristic of XML and its working principle of the main memory/additional memory, and combines service-based mid-ware technologies. The system, by visiting the “main memory” in the server, the newest XML data primarily and visiting corresponding subsystem as an auxiliary, realizes data uniformity through duplication partition. This method enhances the data processing efficiency to a certain degree. It realizes a mechanism for synchronical data transmission.
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Computer Engineering. 2007, 33(17): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2007.17.038Based on the integration demand of multi distributed and heterogeneous relational databases within an enterprise, a metadata dictionary pattern is designed to sustain upper integration access interface and to depict the lower databases’ network location, data schema and data content. A denotation of universal query request orienting integration environment and heterogeneous database is given. Based on the metadata dictionary, a dynamic query algorithm to join relevant database’s multi tables changing with the change of access need involved in a query is put forward, and the algorithm is demonstrated.
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Computer Engineering. 2007, 33(17): 114-116. https://doi.org/10.3969/j.issn.1000-3428.2007.17.039Through analyzing the data flow in iSCSI-based IP-SWAN system, this paper proposes stochastic Petri net model (SPNM) of IP-SWAN system and a novel SPNA method for computing system I/O response time using equivalent conversion of serial or parallel transition. The performance evaluation and prediction are made by SPNA method. Theoretical analysis shows that bandwidth is the bottleneck of IP-SWAN performance in low-speed network, the I/O response time is reduced through enhancing the cache hit rate for read operation and CPU processing power at central server in high-speed network.
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Computer Engineering. 2007, 33(17): 117-119,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.040A new P2P agile trust model is proposed so as to meet the security need in the partially decentralized topology P2P network. Computing trust value is agile for locating in peer group or between peer group. The paper introduces the strategy about computing trust value, maintaining the record of history remember, preventing sybil attack and slandering and cooperative cheat. Designed and implemented prototype system indicates the model is feasible.
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Computer Engineering. 2007, 33(17): 120-122. https://doi.org/10.3969/j.issn.1000-3428.2007.17.041Basing on some applications of embedded Web technology, this paper discusses one method that uses M/M/1 queuing theory of one single service window’s waiting strategy to construct the evaluating model of embedded Web system performance. One embedded Web system which realized by ARM and uCLinux is realized in practice. It describes how to use the model to evaluate the network performance and improve its capability.
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Computer Engineering. 2007, 33(17): 123-124,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.042Frequently join or leave of node in Chord system must increase the maintenance overhead. To decrease the overhead, a new join algorithm, namely SPJoin, is proposed. SPJoin reduces the total join overheads. Theory analysis shows the probability of lookup finger entry is less than 1/2logN when SPJoin constructs each finger entry. In the worst case, the lookup hops that the joining node constructs the finger table is O(logNloglogN). The simulation shows that compared to ChordFingerPNS, SPJoin can decrease the join overheads greatly while slightly affected the lookup performance.
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Computer Engineering. 2007, 33(17): 125-127,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.043This paper designs a scalable MPLS sparse-mode multicast algorithm. With tunneling technology and non-branching nodes technology, the algorithm implements shared-tree multicast over MPLS. Using tunneling technology to implement multipoint-to-multipoint shared-tree multicast can solve one of the difficulties of MPLS multicast: mp2mp label distribution. The paper also introduces the implementation of the MPLS shared-tree multicast in NS-2 and analyses some simulated outcomes.
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Computer Engineering. 2007, 33(17): 128-130. https://doi.org/10.3969/j.issn.1000-3428.2007.17.044Proactive service broking middleware (PSRB) provides a few resource agents to proactively monitor the resources on grid nodes and forecast their future availability. Predictions are accepted as the primary fact for PSRB to select the best grid node for job assignment. This article proposes a new prediction algorithm, which is multi-variant resource performance forecasting technique, to make the grid perform more efficient.
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Computer Engineering. 2007, 33(17): 131-133,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.045Error-correcting code’s decoding algorithm always takes up most time and memory of DSP, due to its complexity in the communication system. According to the problem, a novel tache code—Tach, as like tache counter, is presented, which is coded and decoded by right and left shifting, consequently need not store error charts, thus simplifies decoding algorithm and can be easily implemented based on DSP. The emulation and capability analysis, comparing with Hamming, BCH and RS codes, indicate that Tach code is an efficient and practicable error-correcting code based on DSP. The codec has been implemented using TMS320vc5410.
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Computer Engineering. 2007, 33(17): 134-136. https://doi.org/10.3969/j.issn.1000-3428.2007.17.046Multimedia ring tone(MRT) service is a value-added service which makes multimedia as the ring tone. Considering the property of MRT service and the architecture of network of IP multimedia subsystem(IMS), this paper proposes a solution using multimedia ring tone services platform(MRTSP) to provide value-added MRT services, including the design of system and signal flow. It analyzes the characteristics related to the solution and makes a summary.
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Computer Engineering. 2007, 33(17): 137-139. https://doi.org/10.3969/j.issn.1000-3428.2007.17.047This paper aims at voice traffic characteristics of Tencent QQ, which is the currently popular Internet instant communication software. It deeply focuses on how to effectively identify QQ voice traffic based on deep packet inspection(DPI) and intelligent session association(ISA) technology, then presents a model of identification and related algorithm. The voice identification system and the accuracy, scalibity, robustness of the model and algorithm are validated in core network of China Telecom.
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Computer Engineering. 2007, 33(17): 140-142. https://doi.org/10.3969/j.issn.1000-3428.2007.17.048According to the topologic structure, correlation of degrees, bow tie picture, connected components’ structure, this paper reaches the structure of China education network. The results help to understand the properties of the network and give some new ideas to improve searching strategy and searching engine function.
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Computer Engineering. 2007, 33(17): 143-145. https://doi.org/10.3969/j.issn.1000-3428.2007.17.049This paper uses the simulation soft tool NS-2 and chooses the packet delivery fraction, average end-to-end delay, normalized routing overhead, route discovery frequency to evaluate the performance of the Ad Hoc on-demand distance vector(AODV) and Ad Hoc on-demand multipath distance vector routing(AOMDV). The effects of these parameters on the performance are analyzed and compared by changing the CBR connection numbers and the pause time of the nodes. The research indicates that the AOMDV mulitipath protocol has better performance. The improvement on AOMDV is also proposed.
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Computer Engineering. 2007, 33(17): 146-148. https://doi.org/10.3969/j.issn.1000-3428.2007.17.050In order to increase the speed of genetic watermark and improve the robustness and imperceptible of the algorithm, a new embedding and extracting method with genetic algorithm (GA) is proposed. The AC coefficients of image in DCT domain are modified to embed the watermark. The proposed embedding and extracting method is employed to accelerate the genetic watermark so that genetic watermark could be used in practice. The improved GA is used to optimize both the fundamentally conflicting requirements: robustness and invisibility. The experimental results show both the good robustness under attacks and the high fidelity. The time needed to perform the program is greatly decreased. About 1/3 time is saved.
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Computer Engineering. 2007, 33(17): 149-152. https://doi.org/10.3969/j.issn.1000-3428.2007.17.051This paper studies the sort method and development trend of the information security risk assessment tool, then designs and implements an integrated risk assessment tool based on the popular analyzing method of risk assessment. This tool is a multi expert assessment system. It integrates the functions of the assessment tool of security management, the assessment tool of system software and the assistant tool of risk assessment, and it also introduces the quantitative and qualitative method, which improves the efficiency of risk assessment and ensures the results are more scientific.
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Computer Engineering. 2007, 33(17): 153-155,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.052This paper gives an analysis of Internet key exchange (IKE) protocol and identifies its security holes and design weaknesses and proposes an efficient and improved secure key exchange protocol. Compared with existing key exchange protocol, the proposed protocol is more secure, robust to DoS attacks and has less key exchange time and messages.
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Computer Engineering. 2007, 33(17): 156-158. https://doi.org/10.3969/j.issn.1000-3428.2007.17.053The available fingerprinting protocols are mainly based on the Buyer-Seller model. In the Buyer-Seller model, the seller is the holder of the original copy of the digital product. He embeds the fingerprinting relative to the buyer to make a new copy and sell the new copy to the buyer. When an illegal copy is found, the seller can extract the fingerprinting to trace the illegal buyer. This paper introduces a different model, the secondary distribution mode. Based on the new model, it employs tamper-proof hardware and symmetric encryption technology to design a secure and efficient digital fingerprinting protocol which can be used for on-line trade.
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Computer Engineering. 2007, 33(17): 159-161. https://doi.org/10.3969/j.issn.1000-3428.2007.17.054A new block encryption algorithm using Hénon mapping and multiple active S-boxes is proposed. In this algorithm, the Hénon chaotic mapping is applied to generate the active S-boxes. During the process of encryption/decryption, the active S-boxes are chosen according some rule to encrypt/decrypt plaintext/ciphertext. Using this algorithm, all kinds of files(such as Txt, Bmp, Wav and so on)are encrypted and decrypted, respectively. The cryptoanalysis of this algorithm is also given in this paper. Simulation results show that the proposed cryptosystem performs the higher security, requires less time to encrypt the plaintext, and is more secure against differential and linear attacks.
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Computer Engineering. 2007, 33(17): 162-164. https://doi.org/10.3969/j.issn.1000-3428.2007.17.055This paper describes the technical principles of buffer overflow, and analyzes the methods and features of network attack based on buffer overflow in Windows environment, then gives the development process of exploiting a buffer overflow on Windows. An example of exploiting a buffer overflow in a ftp software is presented to verify the validity of the development process.
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Computer Engineering. 2007, 33(17): 165-167. https://doi.org/10.3969/j.issn.1000-3428.2007.17.056After analyzing the traditional notarization protocol based on complete fair mediator systemically and studying the characteristics of P2P network itself, this paper proposes a notarization protocol of P2P network based on incomplete fair mediator. In this protocol, the mixable cipher system is chosen as a carrier for executing, and both parties of the protocol take the activeness of communication. It is no necessary for them to believe the fair mediator absolutely. The execution purview of the fair mediator is restricted by the protocol, and the execution behavior is also supervised. At last, an alternation process of the protocol is showed, and execution efficiency, security capability and applicability of it are analyzed. The analysis results show that this protocol overmatches the protocol based on complete fair mediator.
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Computer Engineering. 2007, 33(17): 168-170,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.057Software watermark, a novel technology for software copyright protection, is a topic that has recently gained increasing attention all over the world. This paper gives an overview of software watermark including concepts, models, taxonomy and the methods of attacking, and deeply analyzes its novel algorithms developed abroad, and presents their advantages and disadvantages. In conclusion, it points out its development direction based on the analysis of status and problems remaining unsolved.
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Computer Engineering. 2007, 33(17): 171-172,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.058This paper introduces (k, n)-threshold visual cryptography scheme ((k, n)-VCS, for short), based on which visual cryptography scheme with trusted authority ((k, n)-TAVCS, for short) is proposed with actual application as background. Namely, under the control of secret key, any at least k images can only recover the secret image with the approval of trusted authority. It retains the merit of (k, n)-VCS. This guarantees security and satisfies the actual need simultaneously. The plan is carried on the certain analysis, and the simulation results are given.
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Computer Engineering. 2007, 33(17): 173-175. https://doi.org/10.3969/j.issn.1000-3428.2007.17.059Many intrusion detection technologies are complementary to each other. The alert correlation technology analyzes alerts generated from different security products, so that false alerts are greatly reduced, real attacks are more easily discerned, accordingly, the work load on system administrators is largely released. Herein, basic models and technologies of alert correlation are discussed. Important correlation algorithms are analyzed; and development tendencies of alert correlation technologies are also predicted.
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Computer Engineering. 2007, 33(17): 176-177. https://doi.org/10.3969/j.issn.1000-3428.2007.17.060This paper analyzes the security of the chaos-based feedback cryptographic scheme of human video objects and gives a divide-and-conquer attack algorithm against it by using the incompleteness of which the key information diffuses in keystreams. The exhaustive complexity is 221 and the success rate of the attack algorithm is 1. The decrease of key entropy is 235bits. So this encryption algorithm is insecure.
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Computer Engineering. 2007, 33(17): 178-180,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.061This paper presents the design of service-oriented intrusion-tolerant in distributed database systems, which detects intruded services by watching observable effects. After that it carries on damage containment policy, locating and cleaning corrupted data, which ensures that other services can work normally in spite of the systems being intruded, guaranteeing their survivability.
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Computer Engineering. 2007, 33(17): 181-183. https://doi.org/10.3969/j.issn.1000-3428.2007.17.062This paper surveys a new approach to constract a new linear list based on original binary sorted tree using the void chain of leaf node. The information compress from root to leaf node, and all information of tree are collected to leaf node, so CA only signature on last node of linear list. It avoids reconstructing the tree when the node of CRT is changed, reduces expense of maintaining the tree and communication from directory to inquirer.
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Computer Engineering. 2007, 33(17): 184-186. https://doi.org/10.3969/j.issn.1000-3428.2007.17.063On the basis of the analysis of SMTP protocol and SMTP proxy server principle, a SMTP transparent proxy for security detection is developed under Linux environment. Some key techniques are designed and implemented, such as redirecting port, concurrent mail service, getting the address and port of the server, handling annex. System test shows that the SMTP proxy is transparent to users, and can deputize for multiple e-mail services, prevent virus intrusion and leakage of internal content efficiently.
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Computer Engineering. 2007, 33(17): 187-189. https://doi.org/10.3969/j.issn.1000-3428.2007.17.064Control data vulnerability, characterized by buffer overflow, is the most common security problems. When exploited, the attacker tries to rewrite the value of some control data in the target process to redirect the control flow to the prepared malicious code. In this way, the malicious code is executed under the current user’s rights of the target process. Randomization is an effective technique to defend against control data vulnerability, but it still can not protect the control data from being modified. This article proposes a randomization technology based on pointer backups. The model can act upon attacks in time and exactly, so it strengthens the original technique a lot.
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Computer Engineering. 2007, 33(17): 190-192. https://doi.org/10.3969/j.issn.1000-3428.2007.17.065The interferential and junk information has some remarkable negative influences on network communications. However, the network content filtration, which can make the network traffic protocols reorganized and rules matched, is a kind of security technology used in application layer. On the basis of content filtration, through a large number of random samples of network content and quantitative statistics of filtration results, it is reached that the degree of positive influence of content filtration system on network communication efficiency. Moreover, the conclusion about the influence of communications speed and flux on filtration system is drawn.
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Computer Engineering. 2007, 33(17): 193-195. https://doi.org/10.3969/j.issn.1000-3428.2007.17.066This paper proposes a method of eye location based on the color of skin, and constructes the region hybrid projection function. Based on the color of skin, the map of mahalanobis distance to skin in a given image is figured out, and skin areas are segmented. The region hybrid projection function of mahalanobis distance is used in the skin area, which is regarded as the probable face area. Eyes are located and face is detected. Experimental results show the method is effective.
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Computer Engineering. 2007, 33(17): 196-198,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.067This paper proposes a user profile representation based on vector space model together with its dynamic learning algorithm, and studies feature selection in user modeling. A new feature selection method combining term frequency and TFIDF according to part-of-speech tagging is proposed. The experiment indicates that the dynamic learning algorithm can catch and record user’s latest interest in time, thus the user required information can be truly recommended. The experiment also shows that the effect of combining method based on part-of-speech tagging is better than that of using TF or TFIDF separately.
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Computer Engineering. 2007, 33(17): 199-201. https://doi.org/10.3969/j.issn.1000-3428.2007.17.068This paper proposes a feasible change detection method of constructions by use of region feature. It studies the formation of determinant function for region changes, generalization of region characteristics, joint change determinants of multi-factor for regions, minimization of the influence by pixel value variance due to different acquisition time. The method can not only weaken the false change through pixel value variance, but also suit for detecting changes of varying region sizes.
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Computer Engineering. 2007, 33(17): 202-203,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.069To achieve cooperative optimization of a genetic programming (GP)-based dynamic system between structure and parameter during the evolutionary design process, the diversity preservation strategy of evolutionary design topology population is discussed and a topology fitness-sharing & crowding cooperative search algorithm is proposed. This algorithm avoids calculate niche’s radius and punish the topology subgroup by self-adaptive fitness-function, thus the diversity of the topology is well preserved and convergence is prohibited. A case is employed to demonstrate the practicality of applying balanced topology and parameter search in evolutionary design of the dynamic system.
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Computer Engineering. 2007, 33(17): 204-207. https://doi.org/10.3969/j.issn.1000-3428.2007.17.070Vehicle license plate locating is of vital importance in license plate recognition system. This paper proposes a new license plate detection and character segmentation method. The horizontal correlating feature of characters, grads shape and color feather of license plate are taken into consideration to the location of license plates. Multiple scale template matching is applied for license plate characters segmentation using structural information of license plates. Experiments show that the proposed method is reliable and robust in complex environment in actual application.
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Computer Engineering. 2007, 33(17): 208-210. https://doi.org/10.3969/j.issn.1000-3428.2007.17.071This paper introduces the new linear k-partite digraph with single jumping-off and end point. Delete-algorithm, combination-algorithm and output-algorithm are designed. The algorithms with polynomial-time to judge whether or not there is Hamiltonian cycle in the digraph and to count the Hamilton cycle are designed. The algorithm to solve all Hamilton cycles in the digraph is constructed. The algorithmic validity is validated by example. Judgment, count and output of Hamilton cycle are effectually solved.
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Computer Engineering. 2007, 33(17): 211-212，. https://doi.org/10.3969/j.issn.1000-3428.2007.17.072A new filling algorithm based on chain code is transplanted from raster filling algorithm in computer graphics. A new boundary point classifying method is defined by using boundary Freeman chain code. The algorithm fills pixels between left point or right point of contour and raster line with complement operation, thus it can handle arbitrary complicated region without supplementary memory space or additional labeling. Experiments show that the proposed algorithm is faster and more efficient than existing ones.
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Computer Engineering. 2007, 33(17): 213-215. https://doi.org/10.3969/j.issn.1000-3428.2007.17.073This paper investigates the problem of automatic X-corners detection aiming at online camera calibration. Since X-corners are coplanar, a plane-to-plane transform is introduced and rough location of X-corners is realized. Within the area of rough location, X-corners detection operator and the energy center of the area to obtain the accurate location are utilized. This method is applicable in both whole and local illumination owing to integrating the extraction and arrangement of the corners. In addition, when some corners are unable to be detected, others can be detected and arranged correctly. The prosented method is automatic, accurate and robust in automatic online camera calibration.
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Computer Engineering. 2007, 33(17): 216-218，. https://doi.org/10.3969/j.issn.1000-3428.2007.17.074The actual gait of robot significantly bias from the planned one for the low rigidity of the robot’s joints, which is generated by fixed shapped walk loci in the RoboCup 4-legged league, and that limits the robot walking speed. According to this, 200 set of coordinates are employed to represent the arbitrary shaped robot walk loci based on previous gait planning, and an improved GA (genetic algorithm) is employed to achieve the optimum shaped walk loci for robot walking. The experiment results show that the actual gait is more efficient for robot walking by the improved walk loci optimization and provides the robot with a fast and smooth gait.
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Computer Engineering. 2007, 33(17): 219-221，. https://doi.org/10.3969/j.issn.1000-3428.2007.17.075After researching the 2-D image reconstruction algorithms, an improved 2-D iterative projection method is presented, so calculation is reduced, antinoise performance is enhanced, and more clear and accurate reconstructed images are obtained. Based on the algorithm above, the software of ICT image processing system is developed with VC++, which improves the quality of reconstructed images, provides experimental data with more convenient and systemic management, and realizes the automatic detection of disfigurements.
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Computer Engineering. 2007, 33(17): 222-224. https://doi.org/10.3969/j.issn.1000-3428.2007.17.076A new dynamic reconfiguration technique and its applications in distributed image processing system are introduced. Based on the pipeline and spatial parallel processing techniques, the new technique combines merits of the two and proposes a dynamic reconfiguration model. In order to improve real time performance in parallel processing system in time and space, optimized judgment is made by the decision cost function, which makes the disassembled arithmetic task best mapped to system architectures. The dynamic technique is verified correct and ascendant in actual system.
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Computer Engineering. 2007, 33(17): 225-227. https://doi.org/10.3969/j.issn.1000-3428.2007.17.077Based on the analysis and study of cosine radial basis function(CRBF), a classification algorithm of neural network based on cosine radial basis function is proposed. Application model is constructed by mathematical model and geometric model, and the parameters of application model are modified through the training process of classification algorithm to make the classification result more reasonable. Classification result and supervision equipment are consistent after application of blast supervision system based on CENTUM CS3000 and Visual Basic 6.0, the factual demand is satisfied. The classification and application model are proved to be highly effective and valuable in practice and academic study.
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Computer Engineering. 2007, 33(17): 228-230. https://doi.org/10.3969/j.issn.1000-3428.2007.17.078This paper approaches and implements a retrieval engine for speech data based on relevance feedback, imposing Sphinx system to transfer audio file to text file then indexed by Lucene system. To improve the quality of the query answering, the paper employs an overall relevance feedback, including local feedback and global feedback. It improves the system’s accuracy and dynamic characteristic. Experimental results prove the engine meets the users’ demands and it’s of practice value.
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Computer Engineering. 2007, 33(17): 231-233. https://doi.org/10.3969/j.issn.1000-3428.2007.17.079To optimize the cost function for unit selection in the corpus-based TTS system, a certain number of sentences should be preselected and synthesised. These sentences’ mean opinion scores (MOS) can be got so as to maximize the corrrelation between the concatenative cost and the MOS. This paper proposes the concepts of sum of normalized contextual errors (SNCE) and corpus-similarity (CS) based on the TH-Coss corpus of women provided by Tsinghua University. It gets the preselected-sentences and uses the rest of the sentences to replace the TH-Coss corpus using the guideline of minimizing SNCE. Experimental results show that the CS between the preselected-sentences and the TH-Coss corpus rises greatly. And it is valid to replace the TH-Coss corpus with the rest of the sentences for the CS between them reaches 0.995 5.
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Computer Engineering. 2007, 33(17): 234-236. https://doi.org/10.3969/j.issn.1000-3428.2007.17.080In FIRA MIROSOT robot-soccer game, the system of vision is the unique way throught which the whole system obtains the global information. The speed and precision of the vision system has important effect on the result of the game. According to the disadvantage of the traditional vision system, this paper puts forward a new design of color sign, and improves a method on color space conversion, color verdict and color image segmentation, so it dramatically reduces the work of calculation. Experimental results show the design has much supperiority on speed and precision.
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Computer Engineering. 2007, 33(17): 237-238,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.081This paper defines 10 kinds of mouth shapes. The MFCC feature of speech is extracted to recognize vowel (a, i, u) through SVM classifier. According to corresponding quantified speech energy, the speech is mapped to mouth shapes sequences, and median algorithm filter and “odd point” eliminating are undertaken. The algorithm has been applied to the system of face animation driven by speech and achieves good results.
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Computer Engineering. 2007, 33(17): 239-240. https://doi.org/10.3969/j.issn.1000-3428.2007.17.082This paper puts forward a new method for detecting whether a point is within a polygon. The method is composed of two sections, namely, pretreatment for the obtainment of all forked points of the polygon P and detection for finding out related points and edges by using binary search, according to the parity of the number of the related edge which detection line passes through to test wheter a point is within tge polygon. The method can deal with abnormal conditions which ray-crossing algorithm can not and need not handle all edges of polygon in the detection process. Experimental results show that the method is robust and efficient in computation.
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Computer Engineering. 2007, 33(17): 241-242,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.083Based on the analysis of current controller combination form, a new POI+PLC+IPC form is presented. For hardware, it has high reliability and powerful function with multiple CPUs. The form can be directly connected to the Intranet then to Internet for network management. It has been successfully applied to several kinds of textile machine’s control systems, and its good performance has been proved.
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Computer Engineering. 2007, 33(17): 243-245,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.084The deficiency of the current WebGIS is analyzed, and a new ES-SDGIS is provided using J2EE technology based on the instances of out-of-code buildings in Shanghai. Problems such as inefficient compatibility, complicated development and distribution, and tight coupling are solved within the system; also the fuzzy inference function is added. This article discusses the component design, knowledge class and expression, synthesis fuzzy evaluation model, and the Matlab program calling under the Web.
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Computer Engineering. 2007, 33(17): 246-248. https://doi.org/10.3969/j.issn.1000-3428.2007.17.085Aiming at the faults that the current electrical equipments maintenance and CAA system can not design experiment report or compatible heterogeneous database, this paper gives a software architecture with data abstraction and object oriented style connection with system style, on which an electrical equipments maintenance and CAA system is designed. The system, with FrontPage designing its experimental report, dynamically generates experiment report, builds database table, and adds entity domain object by using technologies of Hibernate, HtmlParser, XML. The system is compatible with heterogeneous database. A key code for system realization is given.
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Computer Engineering. 2007, 33(17): 249-250,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.086To get the maximal operation effectiveness of multiple radars in the defence area, and to oppose the sudden attack object, so it is necessary that netting existing radars availability. This paper according to the requirement of netting in the present defence area, adhibits improved particle swarm optimization algorithm with disturbance term(PSO-DT) embattling optimize. Simulation result indicates it satisfies the netting requirement.
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Computer Engineering. 2007, 33(17): 251-253. https://doi.org/10.3969/j.issn.1000-3428.2007.17.087Modern network based data acquisition and condition-based monitor system should be with large communication capacity, good real-time and adaptiveness to the complicated environment. A distributed data acquisition and condition monitor system based on DSP and LonWorks is proposed. Its intelligent DSP-based nodes are powerful in data acquisition, handling and analysis. The network communication is programmed by object-oriented technique with the protocol of collision-predictable algorithm to guarantee large communication capacity and good real-time. Its hardware and software architectures are described in detail.
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Computer Engineering. 2007, 33(17): 254-256. https://doi.org/10.3969/j.issn.1000-3428.2007.17.088To solve real-time quality information acquisition and other issues under site-specific quality control circumstances, this paper discusses the design and application of embedded quality management instrument with integration of network as well as Bluetooth technology. It also does some research on the key methods of device including the realization of Bluetooth communication, memory management and so on. It justifies that embedded quality management instrument can achieve point-to-point and point-to-multipoint wireless data transmission through Bluetooth technology, and realize remote monitoring and management of CNC machine tools and relevant process points with network technology. The manager will play an important role in numerical control circumstance.
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Computer Engineering. 2007, 33(17): 257-258. https://doi.org/10.3969/j.issn.1000-3428.2007.17.089This paper introduces an application of CAN of fuel cell vehicles. A new CAN application layer is designed for the control network of fuel cell vehicles. Messages in the network are classified and the priorities of messages are assigned according to their classes with the redefined ID field of CAN2.0. The protocol includes specific destination communications and broadcast communications. The hardware and software of CAN is discussed emphatically, which is designed based on P89C58×2FN of Philips.
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Computer Engineering. 2007, 33(17): 259-261. https://doi.org/10.3969/j.issn.1000-3428.2007.17.090Based on the practical application of the minitype stratosphere verifying airship, the basic principle of INS/GPS integrated navigation system adapted to this airship is introduced. Integrating with the characteristics of high performance fix-point DSP TMS320F2812 and double interface RAM CY7C028, a navigation computer used as the calculated is designed while the hardware frame and software flow chart of the integrated navigation system are given. The results of flying experiment suggest that this system has good real-time property and the measuring accuracy meets the design requirements. It supplies some theory base for the design of integrated navigation system of stratosphere airship.
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Computer Engineering. 2007, 33(17): 262-264,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.091DLL may generate an accurate delay which is rarely affected by P.V.T conditions, so it is used to generate stable delay or multi-phase clocks. A novel method of digital delay-locked loop is addressed, which utilizes a flip-flop to detect a phase difference. Simulation indicates that 0°～360° phase shift is supported and its locking time, since reset, is 2 688 reference clocks. Under the 0.35μm SMIC digital CMOS process, the precision reaches 200ps and the supported frequency range spans from 23MHz to 200MHz. The programming feature is also available, which facilitates the use of specifying specific delay.
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Computer Engineering. 2007, 33(17): 265-266,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.092This paper presents an effective license plate location algorithm, which employs wavelet transformation and intensity moment to extract number plate from the complex-background images. Noticing this characteristic that the wavelet analysis can save image details very well, this paper defines an intensity moment function to search locality of the license plate, which can extrude the differences of characters and other signals. The simulation result indicates that the method is potent.
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Computer Engineering. 2007, 33(17): 267-269. https://doi.org/10.3969/j.issn.1000-3428.2007.17.093Considering the data exchange between enterprise financial systems and corporate banks, taking the embedded direct connection interface of China Merchants Bank for an example, the paper discusses the design and development process of the bank-corporate express system interface. By communicating with the enterprise end in SOAP message and interchanging with the bank end in multi-thread calling way, this system enhances its maintainability and expandability, and improves the efficiency of the performance. The system runs well now.
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Computer Engineering. 2007, 33(17): 270-272. https://doi.org/10.3969/j.issn.1000-3428.2007.17.094The paper presents the features and kernel structure of µC/OS-Ⅱ, discusses the realization methods of porting µC/OS-Ⅱto TMS320LF2407 DSP based on DSP architecture. At the same time, it introduces the most important and difficult problems in the course of porting µC/OS-Ⅱand summarizes the general methods for porting it to DSP.
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Computer Engineering. 2007, 33(17): 273-274,. https://doi.org/10.3969/j.issn.1000-3428.2007.17.095This paper enhances the ability of interaction of MHP set-top-box by constructing Java runtime environment as a necessary technical approach. It introduces Java technology, software structural model of MHP set-top-box, basic concept of embedded Java virtual machine(JVM) and software layered structure of Kaffe(an open-source Java virtual machine). The process of Kaffe’s transplantation and implementation on the platform of Ali’s set-top-box is explained, the policy of performance optimization for Java virtual machine under embedded environment is presented. The final result proves that the success of transplantation and feasibility of policy about performance optimization for JVM’s execution engine.
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Computer Engineering. 2007, 33(17): 275-277. https://doi.org/10.3969/j.issn.1000-3428.2007.17.096The MPC8270 is a versatile communications processor that is widely used both in network and communication system. This paper expounds how to communicate between UART serial ports by using the SMC (serial management controller) of MPC8270. It also analyzes the structure of the serial port driver and how to load the serial port driver in the VxWorks BSP (board support package). This serial ports driver which has been applied and tested for a long time runs steadily in the whole system.
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Computer Engineering. 2007, 33(17): 278-279. https://doi.org/10.3969/j.issn.1000-3428.2007.17.097This paper brings forward a new viewpoint of using balanced ternary half-adder in the ternary optical computer. A half-adder principle plan is designed based on this viewpoint. Compared with adder of tradition binary electric computer, the strongpoint of this design is that subtraction can be done without complementing code. The add-rule of balanced ternary is discussed and the work methods of balanced ternary half-adder are also provided, which are the theory guidance of Boolean calculator and extended research of ternary optical computer.
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Computer Engineering. 2007, 33(17): 280-282. https://doi.org/10.3969/j.issn.1000-3428.2007.17.098This paper uses two-sided hypothesis test to check the change of update arriving interval and computes the adjusting value of frame duration accurately according to current network condition, so that the deficiency of original NEO protocol’s simple comparing and imprecise adjusting is improved. The voting right is delivered to game engine to avoid forcing players to vote. Simulation results show that the improved frame duration can be adjusted to adapt to network condition steadily which is closer to real network condition, and the protocol performance is enhanced to some extent.
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Computer Engineering. 2007, 33(17): 283-封三. https://doi.org/10.3969/j.issn.1000-3428.2007.17.099This paper presents an approach to integrate simulation model with Visual C++ easily by translating simulation model to embedded C++ codes. The advantages of Simulink and Visual C++ are fully used by this approach. According to a real example the development steps and realization of HILM system based on this approach is discussed.
2024
Volume 50 No 4
Volume 50 No 4
(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