20 September 2008, Volume 34 Issue 18
-
Select all|
-
Computer Engineering. 2008, 34(18): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2008.18.001In H.264, intra prediction is employed to reduce energy of prediction error. The order of Intra block encoding is from left to right horizontally and from top to bottom vertically, so the prediction reference pels can only appear on the left side or upside of the current block, without ideal predicted result sometimes. In this paper, a new Intra 4×4 prediction algorithm based on flexible order of subblocks encoding is introduced, with improved prediction modes and a new set of reference pels. It realizes RD optimization of intra Macroblock(MB）encoding by mode decision of subblock grouping and subblock ordering. Experimental results show that compared with the standard intra prediction mode of H.264, this method can gain 0.4 dB of PSNR averagely.
-
Computer Engineering. 2008, 34(18): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2008.18.002By defining an intuitionistic fuzzy addition operator, the intuitionistic fuzzy relation Ra is modified. The series fuzzy relations defined by Mizumoto are extended intuitionistic fuzzy relations naturally, based on intuitionistic fuzzy triangle norm and its residual implication operator in this paper. By using an example, nine reasonings based on different intuitionistic relations are researched comparatively from eight sides. For both intuitionistic fuzzy hypothetical reasoning and intuitionistic fuzzy rejection reasoning, Rs, Rg and Rgg are the best intuitionistic fuzzy relations, Rsg, Rm,, Ra and Rgs take the second place, and Rss and Rc are the worst.
-
Computer Engineering. 2008, 34(18): 7-9. https://doi.org/10.3969/j.issn.1000-3428.2008.18.003This paper proposes an improved compressed cache replacement policy——Modified LRU Replacement Policy for Compressed Cache(MLRU-C) based on modified Least recently Used(LRU) policy for improving compressed cache replacement policy. MLRU-C can use the extra tag in compressed cache to construct shadow tag mechanism, which can detect, predict, and correct bad replacement decisions made by LRU policy so as to improve performance of compressed cache replacement policy. Experimental results show MLRU-C can decrease L2 compressed cache miss rate by 12.3% compared with conventional LRU replacement policy.
-
Computer Engineering. 2008, 34(18): 10-12. https://doi.org/10.3969/j.issn.1000-3428.2008.18.004A new image matching method based on mirror image is proposed. A new image acquisition system is devised to obtain the mirror image of an object. Image matching spatial dimensions can be degraded from 2D to 1D based on the properties of mirror image. To make sufficient use of the information in color HSI space, multi-pass correlations are calculated, and the H, I, and S components’ respective correlations are all taken into account to efficiently improve the matching accuracy. Reverse sequence restriction are introduced to filter the relevant points above obtained and to eliminate the error matching points. Experimental results show that the image matching results are satisfied.
-
Computer Engineering. 2008, 34(18): 13-16. https://doi.org/10.3969/j.issn.1000-3428.2008.18.005To improve the accuracy of ship hold liquid level, the nonlinear characteristics of level signals are exploited. A novel method for analyzing the water level signals based on wavelet de-noises technique and Empirical Mode Decomposition(EMD) has been developed. Wavelet transformation with translation invariance is adopted to eliminate the effect of abnormal signals, and the new signal is decomposed into Intrinsic Mode Functions(IMF) by EMD. After removing high frequencies IMFs according to the given confidence degree, the low useful frequencies IMFs are extracted to reconstruct the true level signal. The results show the proposed method is reasonable and suitable to nonlinear and non-stationary water level signal.
-
Computer Engineering. 2008, 34(18): 17-18. https://doi.org/10.3969/j.issn.1000-3428.2008.18.006To solve the Media Independent Handover(MIH) security issue when the mobile node roams into the foreign network, this paper provides a key distribution solution based on diameter protocol to set up trust relationship between the mobile node and the MIH server, and offers the integrity protection to the MIH signaling by using the message authentication code mechanism. It proves the security of IKEv2 pre-shared key distribution by using BAN logic, and analyzes the performance of this solution. According to the analysis result, the performance of this solution is better than other related solution.
-
Computer Engineering. 2008, 34(18): 19-20. https://doi.org/10.3969/j.issn.1000-3428.2008.18.007Aiming at the situation that product configuration can not adapt to different products and knowledge expression is complicated, product configuration based on product characteristic vector is presented. Under the condition of quantifiable product characteristics, the model of product configuration based on product characteristic vector is constructed, and the basic theory and process of knowledge expressions are given. Introducing of product characteristic vector realizes the transformation from the description of natural language of product characteristics into that of math language. Constraints attached to components are related to product characteristic vector, which makes constraint representations simple and concentrated, reducing the difficulty of knowledge expression. And a successful case is illustrated.
-
Computer Engineering. 2008, 34(18): 21-23. https://doi.org/10.3969/j.issn.1000-3428.2008.18.008An embedded 3-D digital imaging scheme with Digital Signal Processor(DSP) based on multi-thread technique is presented, which utilizes the principle of temporal sequential frequency-varying fringe digital projection. This approach uses the configuration tool of DSP/BIOS real-time operating system to implement a multi-thread DSP application software, so as to realize the pipeline processes of the fringe projection, data acquisition, and automatic fringe analysis. The software pipeline is also adopted for the calculation of phase-map rebuilding. Experimental results show that this scheme can implement fast 3-D surface measurement.
-
Computer Engineering. 2008, 34(18): 24-26. https://doi.org/10.3969/j.issn.1000-3428.2008.18.009Product Kansei customization model based on Kansei engineering is established to make product customization model more suitable for mass customer without special knowledge. According to the imported concepts of fittings Kansei performance index and product Kansei performance matrix, product Kansei performance is quantified. The solution to product engineering configuration corresponding to product Kansei performance requirement is found with the AHP. Practical application of this model is presented in a customer co-design system based on Web and virtual reality technology.
-
Computer Engineering. 2008, 34(18): 27-29. https://doi.org/10.3969/j.issn.1000-3428.2008.18.010Because the lifetime of Wireless Sensor Networks(WSN) is restricted by the energy of nodes, this paper presents an energy saving algorithm based on cluster head prediction. The approximate linear relationship between the length of data packets and energy consumption for sending, receiving and processing data is analyzed, and an energy consumption model with energy saving algorithm is given. According to the historical fused data, the data of cluster heads is predicted through grey prediction algorithm. With the energy saving algorithm, the communication frequency between cluster head and non-cluster head node is reduced, and the round cycle of cluster head is prolonged at low energy cost. The simulation results demonstrate that the algorithm is efficient for reducing dead speed of nodes and increasing the network lifetime.
-
Computer Engineering. 2008, 34(18): 30-32. https://doi.org/10.3969/j.issn.1000-3428.2008.18.011This paper proposes an adaptive blind equalization algorithm for Minimum Mean Squared Error(MMSE). Like RLS algorithm, the method recursively updates correlation matrix and its inversion according to the matrix inversion lemma, thus ensures convergence and is not sensitive to initialization. Unlike many subspace methods, the algorithm does not require channel order estimation and it is robust to channel order mismatch. Fast convergence and online property enable it to be used in real-time communication applications. Simulation results show that the algorithm has good performance of online equalization.
-
Computer Engineering. 2008, 34(18): 33-35. https://doi.org/10.3969/j.issn.1000-3428.2008.18.012In Distributed Control System(DCS), real-time tasks must be finished before their deadlines, otherwise the catastrophes occur. Therefore, fault-tolerance must be offered for DCS. Based on EDF algorithm and task duplication technique, fault-tolerant scheduling algorithm is presented for DCS. And a heuristic static algorithm for assigning tasks to processors is given. Genetic Algorithms(GA) is adopted to optimize the deadlines of primary copies in order to improve utility of processor. The simulation experiments show that the algorithm is effective.
-
Computer Engineering. 2008, 34(18): 36-38. https://doi.org/10.3969/j.issn.1000-3428.2008.18.013It is very difficult for the users to find what they need fast and effectively. In order to satisfy the users’ requirement, this paper gives a system structure of the distributed database search engine, which implements the intellectualized search and orientation. The construction of the search engine focuses on the establishment and optimization of the index. By the creation and optimization of the index, and using a proper collate algorithm, the search engine can give the users what they need at first. Thus, it can improve the search efficiency, recall and precision ratio. The experiment shows that the recall ratio is 90.02% and the precision ratio is 89.78%.
-
Computer Engineering. 2008, 34(18): 39-41. https://doi.org/10.3969/j.issn.1000-3428.2008.18.014Text clustering, one of the most important research braches of clustering, is the application of clustering algorithm in text processing. This paper discusses different Vector Space Model(VSM)-based clustering algorithms and presents an improved text clustering algorithm——Level-Panel(LP) algorithm. In addition, according to the effects of clustering for the corpus, it presents optimizations of clustering algorithm, including dimension determining, feature selection, etc. It is proved that LP algorithm can effectively reduce the time spending in clustering process. It is high in practicability and flexibility.
-
Computer Engineering. 2008, 34(18): 42-44. https://doi.org/10.3969/j.issn.1000-3428.2008.18.015Web services composition is very important to improve efficiency of software development in Service-Oriented Architecture(SOA). This paper reviews services composition methods based on Petri net. As mostly methods are based on P/T_ or high-level Petri nets, the resources are not suitable for services composition, and cause low efficiency of composition process. Elementary Petri Net(EPN) and new translation rules are proposed to model services, and services are composed dynamically according to conditions of input places, which are converted into classical artificial intelligent problems to be solved. A real example shows that EPN is suitable for dynamic services composition.
-
Computer Engineering. 2008, 34(18): 45-47. https://doi.org/10.3969/j.issn.1000-3428.2008.18.016To elicit the requirements, identify the requirements commonness and variability correctly is the key for Software Product Lines(SPL) success, which needs a particular requirement process and methods. This paper puts forward a multidimensional and hierarchical requirement process, which carves up the SPL analyse space from multi-hierarchy, observes the SPL requirements form n-dimension, and utilizes PR-Context matrix to ensure the objectivity of domain requirement analysis. It is beneficial to the practice of SPL requirement engineering.
-
Computer Engineering. 2008, 34(18): 48-50. https://doi.org/10.3969/j.issn.1000-3428.2008.18.017Using the method of binary system in association rule data mining may produce some redundancy patterns. This paper proposes an algorithm based on two levels data mining of binary transaction attributes, namely MLADM algorithm. It gets maximum possible frequent patterns set on high level patterns, and validates these patterns on low level patterns to get first long frequent patterns. The experiment on real datasets proves that MLADM is effective on mining long patterns on dense dataset and can avoid producing redundancy patterns.
-
Computer Engineering. 2008, 34(18): 51-52. https://doi.org/10.3969/j.issn.1000-3428.2008.18.018To compute the weight of information feature is a very important research work in information classify and pattern matching, a method of principal feature selection based on reformative algorithm ReliefF is presented in this paper. The main work as fellow: reformative ReliefF algorithm is used to take out some irrelevant features from originality features, normalization is worked, and the principal feature is selected. Using the method to select the principal feature will reduce the dimensionality significantly. Experiment provides that, using the method, only 10 principal features is remained from 34 originality features, and the computing cost of the classify program can be decreased, at the same time, the precision of the classify program can be increased.
-
Computer Engineering. 2008, 34(18): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2008.18.019This paper proposes a job scheduling algorithm based on the resources availability. It takes account of the historical record of resources and the current resources information. Based on the resource availability, it improves the original Min-Min algorithm. GridSim is used to simulate the experiment based on the algorithm, and is compared with experiment based on Min-Min algorithm. Simulation results show that job-scheduling algorithm based on the availability improves the cluster’s efficiency, shortens the average job complete time.
-
Computer Engineering. 2008, 34(18): 56-58. https://doi.org/10.3969/j.issn.1000-3428.2008.18.020When handling the problem of collision in Radio Frequency Identification(RFID) system, the algorithm of this paper utilizes choosing collision-bit randomly to impact the braches of backtracking and dynamic tree, in order to let more pairs of tags that just have one collision-bit identified at one time, which can improve efficiency of tags identification. In addition, the algorithm improves the message handling capacity through reducing parameters that the reader sends to tags for checking. The logic of tags based on this algorithm is simple, which will promote the technology of RFID popularized.
-
Computer Engineering. 2008, 34(18): 59-61. https://doi.org/10.3969/j.issn.1000-3428.2008.18.021Knowledge Base of Industry Infomanization(KBI) is a type of knowledge base system with complex structure and functions. In order to solve the problems of knowledge sharing and reusing, the ontology is used to abstract and analyze the industry informanization knowledge, and industry knowledge is related based on ontology. It also introduces and analyzes the Jena based on the knowledge ontology, including the problems of reasoning, components of Jena and its reasoning mechanism. The syntax of reasoning rule is presented. An example of the use of Jena in semantic reasoning is given. The results show it can promote the query efficiency.
-
Computer Engineering. 2008, 34(18): 62-64. https://doi.org/10.3969/j.issn.1000-3428.2008.18.022UML can be used to accomplish the system modeling from different views. There are information redundancy in different views, so that the views may be inconsistent. This paper proposes an approach to analyze sequence diagram which has many different logical semantics. To deal with the hierarchy structure of statechart, finite state automata is used in this paper, and an automata decomposition algorithm is proposed to get an automata tree. A new model consistency criterion of sequence diagram and statechart, as well as a new structure of Promela is proposed. Model consistency is checked between sequence diagram and statechart with the model checker SPIN.
-
Computer Engineering. 2008, 34(18): 65-66. https://doi.org/10.3969/j.issn.1000-3428.2008.18.023Quantum-behaved Particle Swarm Optimization(QPSO) algorithm makes change for the evolutionary strategy of particles, and the particles has much broader search space, which helps to avoid falling into local optimal. This paper transforms QPSO into binary QPSO, and combines QPSO with attribute reduction algorithm, presents attribute reduction based on QPSO. Experimental results show that this algorithm can achieve much better reduction result than Hu algorithm and particle swarm optimization reduction algorithm.
-
Computer Engineering. 2008, 34(18): 67-69. https://doi.org/10.3969/j.issn.1000-3428.2008.18.024By studying several key characteristics of Internet Protocal Television(IPTV) large concurrency applications, a media file format named cl4 is proposed. In order to work well in IPTV large concurrency applications, this file format uses several media indexing and storage strategies, including video/audio mixture storage and block-level media storage. An IPTV server using cl4 file format is designed and implemented. Detailed performance evaluation and test results demonstrate that IPTV server can work more efficiently by using cl4 file format.
-
Computer Engineering. 2008, 34(18): 70-71. https://doi.org/10.3969/j.issn.1000-3428.2008.18.025Because of permanently storing and hiding intruder’s codes, persistent Rootkit becomes a very important issue of computer security. This paper applies the cross-view method to construct the monitor system. It is implemented to decide whether the system is installed persistent windows Rootkit by analyzing system’s behaviors using file system filter driver and hooking system services. The system detectes Rootkit-hacker defender which is the most classical Rootkit in the real world and some malwares protected by it. Due to the use of low-level driver and not depending on signature, it also has good performance in detecting kernel level and unknown Rootkit.
-
Computer Engineering. 2008, 34(18): 72-74. https://doi.org/10.3969/j.issn.1000-3428.2008.18.026The structure relations between XML data are always regardless while the data are stored, but they are needed during operation. After analyzing the operation characteristics of XML data, this paper designs the coding and parsing arithmetic based on SAX. It travels XML document only once to get a triad of
-
Computer Engineering. 2008, 34(18): 75-78. https://doi.org/10.3969/j.issn.1000-3428.2008.18.027Because the problem that there are some complicated calculations such as non-linear predication function, pointer, array etc. in constraint system, this paper proposes an improved algorithm of constraint problem solving based on symbolic execution method by using constraint satisfaction searching algorithm, decreasing the number of parametric variation in equations set and narrowing down the range of parametric variation’s value. It is proved that this algorithm can produce test case of path coverage testing automatically by experimenting on some program examples which concludes non-line prediction functions and arrays.
-
Computer Engineering. 2008, 34(18): 79-81. https://doi.org/10.3969/j.issn.1000-3428.2008.18.028
Distribution management system based on mobile terminals is studied to solve the problem of information lag, distortion, and information-island in distribution process. A Service-Oriented Architecture(SOA)-based architecture for distribution management system is established by using mobile terminal to collect and display information and Web Service technology to handle and publish data. According to properties of mobile terminals and their browsers, technologies of information display and heterogeneous data formats conversion are studied to develop respective tools. An application system for Apparel Industry is developed as an example to demonstrate the feasibility of the system in kinds of typical mobile terminals.
-
Computer Engineering. 2008, 34(18): 82-84. https://doi.org/10.3969/j.issn.1000-3428.2008.18.029The Multi Dimensional Expression(MDX) statements are often used in the process of multi-dimensional analysis of massive data. How to optimize the statements in order to boost the query speed is one of key issues when constructing the OLAP systems. By the predefined materialized views, the query statements can be rewritten and executed against one single table instead of the join of one fact table and several dimensional tables. The paper presents the thought of how to select the candidate materialized views and also the experimental results, which show that the boosting effect is more encouraging while dealing with more data via more complicated MDX statements.
-
Computer Engineering. 2008, 34(18): 85-86. https://doi.org/10.3969/j.issn.1000-3428.2008.18.030The existing algorithm of search engines merely works on interlinks among Web pages while putting aside ordering of original and copied articles, and rising original technical websites are put into great disadvantages in competition with those earlier websites. In order to develop these rising technical websites and enhance fair competition on the Internet, this paper presents a new ranking algorithm which gives priority to those original articles and promotes their search rankings and therefore can be employed by professional search engines.
-
Computer Engineering. 2008, 34(18): 87-88. https://doi.org/10.3969/j.issn.1000-3428.2008.18.031This paper analyzes the factors which affect the quality of real-time in text categorization, that is the high time-consuming problem of word segmentation, and the excessively high dimension of character space. Based on the real-time application of Web filter, a real-time text categorization approach is proposed. The approach improves the rate of text categorization by reducing the processing of word segmentation and the dimension of character space. It maintains the effect of text categorization by optimizing the selection of character item, and implements a real-time text classifier based on Bayesian theory. Experimental results show that this approach improves the rate of text categorization effectively, and the precision and recall is maintained at 85 percent and 94 percent.
-
Computer Engineering. 2008, 34(18): 89-92. https://doi.org/10.3969/j.issn.1000-3428.2008.18.032The handling of Web service composition of fault-tolerant is a valid method to improve the usability and reliability of service. This paper classifies the failures of the runtime of Web service composition according to the severity degree. It also suggests a fault-tolerant framework during the execution of WebJetFlow, which designs and achieves corresponding online handling policy, aiming at different degree failure in the execution of WebJetFlow, making the function as well as the service quality guaranteed.
-
Computer Engineering. 2008, 34(18): 93-95. https://doi.org/10.3969/j.issn.1000-3428.2008.18.033The buggy codes of device drivers usually account for most of the OS kernel crashes. This paper proposes a prototype of writing Linux device drivers in the type-safe language of Java, which effectively improves the system reliability, analyzes framework of Java device driver prototype, design of kernel-mode Java Virtual Machine(JVM) and writing of Java device driver program. USB Ethernet drivers test shows Java device drivers’ advantage in improving system reliability.
-
Computer Engineering. 2008, 34(18): 96-98. https://doi.org/10.3969/j.issn.1000-3428.2008.18.034A group communication system is designed for meeting requirement of large-scale computation task. After describing system framework, it brings forward to the reliable message-passing protocol and membership management protocol. The message-passing protocol can guarantee the reliability of message-passing, even if an agent is mobile, the message will arrive destination. The membership management protocol guarantees the flexibility and expansibility of membership management. What’s more, it can meet the need of the integrity and accuracy of fault detecting and low net load.
-
Computer Engineering. 2008, 34(18): 99-101. https://doi.org/10.3969/j.issn.1000-3428.2008.18.035This paper presents a hierarchical replica location approach based on load balance——RepliLoc. In RepliLoc, replica location is divided into two layers, one is community layer, and the other community alliance layer. Application layer broadcast is used to locate replica on community layer and matching prefix routing algorithms of Tapestry is used to achieve replica location on community alliance layer. Replica location messages are distributed evenly on each node by usiing Hash function and matching prefix to achieve storage load balance. Replica location is localized by community to achieve computational load balance.
-
Computer Engineering. 2008, 34(18): 102-104. https://doi.org/10.3969/j.issn.1000-3428.2008.18.036This paper analyzes the communication requirements of multiple physiological signals in mobile network, and proposes the communication protocol for the remote multiple physiological parameter monitoring system. The protocol is based on the communication protocol for remote ECG monitoring system, and the data structures, re-transmission and synchronization parts of the original protocol are modified. The protocol has been applied in the remote wireless multiple physiological parameter real-time monitoring system, and experiments prove that it fulfills the requirements of the data transmission between the monitor and the server.
-
Computer Engineering. 2008, 34(18): 105-107. https://doi.org/10.3969/j.issn.1000-3428.2008.18.037In order to eliminate the problems in existing principal switch selection algorithm with long selection time and heavy network traffic because of ignoring priority, this paper gives an optimized principal switch selection algorithm. On the basis of that each switch save other switch’s priority, by building of selection time’s optimized function model and the relation model between message number and node number, selection time and network traffic are lowed. Simulation indicates that compared with other algorithm, selection time is reduced by 30%, message number is reduced by 50%, and network delay and crowding are efficiently avoided.
-
Computer Engineering. 2008, 34(18): 108-110. https://doi.org/10.3969/j.issn.1000-3428.2008.18.038How to use a dynamic replication management mechanism to improve the usability and reliability of the data in the network becomes the hot spot of research in recent years. This paper presents a kind of dynamic replication management mechanism based on the trend forecast by using the smoothing arithmetic of time sequence in the economic area to forecast the hot file, and using three different strategies to place, delete, and replace the replica dynamically. It can increase the hit rate in the resource searching efficiently in P2P network, decrease the cost of the whole network, and balance the load of every node in the network through simulation experiments and the analysis of its data.
-
Computer Engineering. 2008, 34(18): 111-112. https://doi.org/10.3969/j.issn.1000-3428.2008.18.039According to Distributed Hash Table(DHT)-based P2P network resource locating methods, this paper introduces virtual node into structured P2P system and makes the most use of regionalization of network access and contiguity of physical nodes to reduce access latency and routing length, and to optimize the routing location when the topology forms. It presents an improved Kademlia-based P2P network resource locating model. The improved model is helpful to solve the problems of expandability and manageability in P2P network. It improves the efficiencies and effectiveness of network resource. Simulation tests indicate that the improved model inherits the merits of DHT and Kademlia, and it is superior to original Kademlia model in routing location, searching success ratio and average logic path length.
-
Computer Engineering. 2008, 34(18): 113-116. https://doi.org/10.3969/j.issn.1000-3428.2008.18.040Traditional remote access configuration mechanism has the following shortcomings: interactive time is long, security is not strong, access control is difficult, the burden of remote access server is heavy and so on. Basing on the newest IKEv2, this paper combines CP payload with DHCP mechanism and implements automatic configuration of remote access client. Experiment shows that the improved mechanism improves efficiency and security of remote access and makes advanced access control easier by adding to user identification and allocation strategy which is based on user group.
-
Computer Engineering. 2008, 34(18): 117-119. https://doi.org/10.3969/j.issn.1000-3428.2008.18.041This paper presents the design of Viterbi decoder for Multiband OFDM(MB-OFDM) Ultra-Wideband(UWB) communication system. The convolutional/punctured codes and the performance of corresponding Viterbi algorithm are analyzed. To achieve the highest data rate desired with hardware efficiency, a folded sliding block architecture is utilized. Under lower data rates, some Processing Elements(PE) in the Viterbi decoder are disabled to save power. The design has been implemented on FPGA and the throughput can be up to 432 Mb/s on a Xilinx Virtex-4 device.
-
Computer Engineering. 2008, 34(18): 120-122. https://doi.org/10.3969/j.issn.1000-3428.2008.18.042Dynamic routing service model is an actual application of service virtualization strategy in the SOA framework. Presently, dynamic service routing model can be categorized as the predictive models and the reactive models. This paper proposes an improved dynamic service routing model which is named Predictive-Reactive Service Routing model (P-RSR model) based on the analysis of these two categories of dynamic service routing model, and the P-RSR model is proved highly effective and reliable in terms of theory and practical performance test.
-
Computer Engineering. 2008, 34(18): 123-124. https://doi.org/10.3969/j.issn.1000-3428.2008.18.043Aiming at the problems of developing software with Tuner card SDK or Video for Windows(VFW), which depends on concrete equipment and high cost, this paper proposes a network television system based on Microsoft DirectShow and COM technologies. The system enhances the generality and declines the cost. And it uses IP multicast technology to transmit data, so that it saves network bandwidth resources and improves the efficiency of data transmission.
-
Computer Engineering. 2008, 34(18): 125-127. https://doi.org/10.3969/j.issn.1000-3428.2008.18.044In recent years, some routing algorithms for connection-oriented LEO satellite communication networks have been developed, but the performance of these routing algorithms depends heavily on the optimality of the initial path establishment, so robustness is not good. This paper proposes a routing algorithm for improving robustness in connection-oriented LEO satellite communication networks. A source satellite can communicate with any satellite, so long as a path exists between the source satellite and the destination satellite. If there exist many paths between the source satellite and a destination satellite, it can search the shortest path on-line, and the time for routing is not occupied by the operation of the algorithm. The performance of the algorithm is evaluated through simulation. Experimentaql results show that the robust routing algorithm is more robust than other routing algorithms for connection-oriented network structure.
-
Computer Engineering. 2008, 34(18): 128-130. https://doi.org/10.3969/j.issn.1000-3428.2008.18.045This paper proposes Energy-Based Multi-hop Clustering(EMHC) algorithm which selects cluster heads according to the priority of residual energy and adopts the minimum inner-cluster communication cost structure. Simulations on OMNet++ show that the cluster heads are evenly distributed, and energy is saved to improve the network lifetime by EMHC algorithm. Its performance is superior to LEACH and HEED.
-
Computer Engineering. 2008, 34(18): 131-133. https://doi.org/10.3969/j.issn.1000-3428.2008.18.046To resolve the NP-complete problem of Minimum Spanning Tree(MST) calculations and meet the performance requirements in actual network environment, a distributed algorithm for searching the MST is proposed. The algorithm is based on the characteristic of MST and utilizes data fusion to establish MST of the network gradually. The algorithm requires only 3×lbn times of information exchanges at most and removes off the redundant information without conventional flooding link-information. Therefore, it has the advantages of high convergence speed and low consumption of resources.
-
Computer Engineering. 2008, 34(18): 134-136. https://doi.org/10.3969/j.issn.1000-3428.2008.18.047To solve problem of the FTP server-cluster’s global balance, this paper proposes a novel load balancing scheme, including the choice of FTP load balancing strategies and the construction of the uniform distributed platform implemented by JXTA. It adopts the adaptive FTP load balancing strategy, called global-local-secondary global, to schedule the download requests of clients dynamically. The cluster is divided into several subsets disjointed mutually, and each subset has only one super node. The negotiation among subsets is implemented by communication of super nodes. The validity of the scheme is testified by experiments.
-
Computer Engineering. 2008, 34(18): 137-139. https://doi.org/10.3969/j.issn.1000-3428.2008.18.048This paper proposes a high-performance and reliable mobile Agent communication model――D-C communication model, which combines domain name resolver and communicator in mobile Agent system. It introduces a universal and location-independent naming method――Universal Agent Identity(UAID). The implementation of the mechanism is described through the creation, movement, access and message transfer and handle of the mobile Agents.
-
Computer Engineering. 2008, 34(18): 140-141. https://doi.org/10.3969/j.issn.1000-3428.2008.18.049The data packet dropout degrades the performance and network utilization of networked control system. The Markov chain is proposed to model the networked control system, to predict the delay and packet loss rate as an important parameter of the quality of service. Based on the dropout rate, a feedback scheduler is used to adjust the sampling periods for tasks of Networked Control Systems(NCS) and network resources. The integrated control-scheduling is realized and the total control performance is optimized. The emulation result shows it is effective.
-
Computer Engineering. 2008, 34(18): 142-144. https://doi.org/10.3969/j.issn.1000-3428.2008.18.050For the issue that more and more popular P2P voice and video transmission application cause great pressure for the underlying communication network, this paper provides the scheme of measuring Skype network topology, and analyzes Skype protocols, communication mechanism and traffic characteristics. Based on analyzing lots of active measuring experimental data and passive capturing communication traffic of Skype, it provides the communication mechanism of Skype, and finds out partly traffic characteristics and protocol behavior characteristics of Skype. Through tests, these conclusions can be used to analyze and control Skype in the LAN environment.
-
Computer Engineering. 2008, 34(18): 145-147. https://doi.org/10.3969/j.issn.1000-3428.2008.18.051This paper presents a replica chain based consistency maintenance algorithm in unstructured P2P systems. It utilizes the broadcasting of update message to create a replica chain of a file when the update is firstly initiated by a replica node. After that update message is transferred through the replica chain without flooding. And the maintenance of the chain is performed by the broadcasted message recorded by every node receiving it. Experiments with this algorithm on the PeerSim platform show that the algorithm is effective.
-
Computer Engineering. 2008, 34(18): 148-150. https://doi.org/10.3969/j.issn.1000-3428.2008.18.052This paper proposes a Visualized Inter-Domain Routing Modeling Language(VIDRML). It provides the capacity of visualized modeling for inner scaling structure of large-scale Autonomous System(AS), relationship of ASes and inter-domain routing policy. Thus, VIDRML can establish multiple models of different abstract granularity in different levels and from different views for inter-domain routing. And this can help designers and network administrator understand topology of large-scale AS and behavior of inter-domain routing better. Meanwhile, it provides the advanced modeling methods for structure design and reusable pattern design of network topology and routing policy. Therefore, it provides support for effective design, implementation and management of AS’s topology and routing policy configuration. Moreover, VIDRML establishes solid foundation for intelligentizing and automatization of inter-domain routing management.
-
Computer Engineering. 2008, 34(18): 151-153. https://doi.org/10.3969/j.issn.1000-3428.2008.18.053This paper introduces a new simple weighted max-min bandwidth allocation method based on main current allocation technology. The algorithm is coupled closely with DCF, in order to ensure the fairness and minimum bandwidth requirement for each flow. Simulations are performed using NS and the results show that the new method can not only satisfy each flow’s minimum bandwidth requirement, but also increase the system throughput. The new method especially adapts single-hop networks in multimedia transmission.
-
Computer Engineering. 2008, 34(18): 154-156. https://doi.org/10.3969/j.issn.1000-3428.2008.18.054P2P network is one of the research hotspots in current time, which is considered as the foundation of next generation network. The paper introduces a transaction management strategy in hybrid network. The strategy utilizes the power of super-peer. Super-peer manages the transactions scheduling on common peers. Common peers check conflict among transactions and send messages to super-peer. According the messages, super-peer schedules transactions in order. The paper demonstrates and simulates the transaction management model.
-
Computer Engineering. 2008, 34(18): 157-160. https://doi.org/10.3969/j.issn.1000-3428.2008.18.055In anonymous communication of MANET, both encryption and MIX strategies are used to defend attacks according to contents and communication pattern. This paper analyzes several known MIX strategies in MANET by probabilistic model check. Results show that these strategies can not defend passive attacks as statistical disclosure attack. In addition, the anonymity, average delay and overhead provided by them would be affected by mobility. Synchronization strategy is proposed. The method has better anonymity, low-latency and little influence by mobility.
-
Computer Engineering. 2008, 34(18): 161-163. https://doi.org/10.3969/j.issn.1000-3428.2008.18.056The paper proposes a novel active vulnerability detection system based on C/S mode. This system is composed of two modules: agent and console. The detection agent, which is a vulnerability scanner based on OVAL Schema, can give an effective and all-sided vulnerability scan as well as reporting the result to the console without any damage to the network. At the same time, the console realizes remote control against the process of scans on several computers and gathering of scan results of the whole network. The test result proves that this system is feasible and advanced.
-
Computer Engineering. 2008, 34(18): 164-166. https://doi.org/10.3969/j.issn.1000-3428.2008.18.057This paper presents a solution of a high speed, low-cost and reconstructable encryption engine based on the AES encryption aiming to solve the balance problem of hardware resources and circuit performance in commercial encryption engines. According to FPGA inherent structural features, the four-level pipeline structure is improved and the encryption module is described with VHDL. By expanding the password encryption engine, the goal of real-time, reconstructability and security is achieved. Compared with some other encryption engines, this encryption engine has a good safety performance guarantee, speed and resources performance ratio.
-
Computer Engineering. 2008, 34(18): 167-168. https://doi.org/10.3969/j.issn.1000-3428.2008.18.058In accordance with the problem that the fast implementation of elliptic curve cryptosystems relies on the efficient computation of scalar multiplication, this paper improves the mixed binary and ternary method to express n, generalizes the mixed binary, ternary and quinary method to express . Based on the computation of double point, triple point, and quintuple point, it computes scalar multiplication nP by using proper operations. Results show that the approaches lead to lower complexity which contributes to the efficient implementation of elliptic curve scalar multiplication.
-
Computer Engineering. 2008, 34(18): 169-170. https://doi.org/10.3969/j.issn.1000-3428.2008.18.059This paper proposes a multi-function digital watermark algorithm based on Discrete Wavelet Transformation(DWT), where the visible watermark’s scaling factors of low frequency and each high frequency are determined by Human Visual System(HVS) and the host image features. Low frequency coefficients of the image embedded with visible watermark are selected to embed invisible watermark using quantization method by appropriate quantifying step size. Experimental results show that the watermarked image generated by the algorithm meets the requirements of visible watermark and the invisible watermark is robust against normal image processing and attacks. The algorithm can realize copyright informed and copyright protected together.
-
Computer Engineering. 2008, 34(18): 171-173. https://doi.org/10.3969/j.issn.1000-3428.2008.18.060This paper proposes a new optimistic fair off-line payment scheme for multi-party aggregate P2P transaction, in which no one has advantage over others. The trusted party need not be involved into exchange unless disputes have occurred. The disputes which might occur are analyzed and handling solution is proposed. Analysis results show fairness of the protocol.
-
Computer Engineering. 2008, 34(18): 174-175. https://doi.org/10.3969/j.issn.1000-3428.2008.18.061This paper proposes a selective encryption algorithm based on quadtree structure. It encodes the bitplane of spatial domain image by quadtree encoded, shuffles and selectively encrypts the data according to the structure of quadtree encoding. The quantity of encrypted data and security of the algorithm is analyzed. Experimental results show that this algorithm has high security, and the quantity of encrypted data is only 50 percent of the normal encryption algorithm.
-
Computer Engineering. 2008, 34(18): 176-178. https://doi.org/10.3969/j.issn.1000-3428.2008.18.062Because some disadvantage of the R-LKH scheme which is one algorithm of the multicast rekeying, such as the inefficient rekeying and high computing spending of group controller and member, this paper proposes an improved R-LKH algorithm which increases the rekeying efficiency and reduces the group traffic by adopting the efficient rekeying algorithm which combinies one-way function and random number. It analyses and compares the traffic of multicast and unicast when the members join or leave the group. The results show that the improved algorithm needs less traffic and computing spending than the R-LKH.
-
Computer Engineering. 2008, 34(18): 179-180. https://doi.org/10.3969/j.issn.1000-3428.2008.18.063This paper investigates the period and complementarity property of Galois FCSR state-sequence, and the complementarity proterty of carry-sequence as well. By analyzing the relationship between a periodic sequence and the 2-adic expansion of a rational number, it is proved that the state-sequence of an l-sequence is eventually periodic and has the same period as that of the l-sequence. It analyzes an l-sequence a with minimum connection integer q, state-sequence s=(s0, s1,…, sn) and carry-sequence c=(c0, c1,…, cn), and proves that si si T/2 , ci ci T/2 q for i≥t, where T = per(a), r = lb(q+1), and t is the time after which s is strictly periodic.
-
Computer Engineering. 2008, 34(18): 181-183. https://doi.org/10.3969/j.issn.1000-3428.2008.18.064When used in application, RC4 cipher technology has some problems, such as weak keys and related key attacks, invariance weakness,, byte bias and so on. This paper presents an improved RC4 cipher technology, which combines the ECC cipher and the RC4 stream cipher. The emphasis is analyzing the efficiency, the management of keys, and the capability of the improved RC4 cipher. The result indicates that the efficiency of the improved RC4 is just a litter lower than RC4 stream cipher while the security is much better than RC4. It has good repellency of the current attacks which aim at RC4 stream cipher. What is more, the improved RC4 cipher has a good way to solve the problems about key management and key update, which is very significant in application.
-
Computer Engineering. 2008, 34(18): 184-185. https://doi.org/10.3969/j.issn.1000-3428.2008.18.065Most intrusion detection methods are dependent on training data sets. Labeled training data sets are difficult to be obtain and one can never be sure that a set of available labeled data covers all possible attacks. This paper proposes a network intrusion detection method based on unsupervised clustering and chaos simulated annealing algorithm. Chaos simulated annealing algorithm is used to optimize clustering results to get the global optimal solution, upgrade the accuracy of classification, and improve the quality of intrusion detection. Experiments are completed on KDD Cup 1999 and expectant results are achieved.
-
Computer Engineering. 2008, 34(18): 186-188. https://doi.org/10.3969/j.issn.1000-3428.2008.18.066This paper analyzes and compares DES, AES in symmetry encryption algorithm and RSA in nonsymmetry encryption algorithm. A new algorithm called hashing combination encryption algorithm is proposed based on the application of map data dissemination on internet. The higher efficiency of AES and the facility of key managing of RSA are combined in this algorithm. Encryption security is improved when the data mix with the key. The experimental results show that the new algorithm satisfies the requirement of data encryption security and efficiency.
-
Computer Engineering. 2008, 34(18): 189-190. https://doi.org/10.3969/j.issn.1000-3428.2008.18.067This paper proposes a plane-based general access structure for secret sharing scheme, which improves the graph-based secret sharing scheme. In a graph, if any two participants in a set of three participants contain an edge in the graph, the set of the three participants belongs to prohibited structure, which can not recover the master key. Otherwise, it belongs to access structure, which can recover the master key. The analysis results show that compared with existing schemes, this scheme needs less storage spending and has higher security.
-
Computer Engineering. 2008, 34(18): 191-193. https://doi.org/10.3969/j.issn.1000-3428.2008.18.068A watermark-based adaptive information hiding algorithm is proposed for the Intellectual Property Rights(IPR) protection for database. The algorithm adaptively chooses an optimal embedding scheme according to the characteristics of the data to make the degradation due to the watermark embedding to be smallest. And the error-correcting coding technology and the majority voting principle are employed to improve the algorithm’s robustness. Experimental results reveal that the algorithm can meet the requirements of invisibility and blind detection as well as good resistance to conventional attacks such as subset deleting, adding, and updating.
-
Computer Engineering. 2008, 34(18): 194-195. https://doi.org/10.3969/j.issn.1000-3428.2008.18.069Steganalysis is an attacking technology on steganography. Steganalysis technology with image carrier judges the existence of embedded data by studying the characteristic of steganographic carrier. The characteristics of embedded data have great effect on steganographic carrier, and can provide important evidence to information detecting. This paper proposes generalized character sequence and two detecting methods based on plain text when the steganographic carrier is images. Experimental results show that the two methods can detect the steganographic data, estimate the information capacity and position of embedded information carrier.
-
Computer Engineering. 2008, 34(18): 196-198. https://doi.org/10.3969/j.issn.1000-3428.2008.18.070In order to improve the robustness, the watermark data is encoded by radix-K linklist which integrates with binary tree and Planted Plane Cubic Tree(PPCT) respectively. The generation of watermark information is based upon quadratic residue theory and Rabin cipher system. The functionality dependency relationship is built between multiple watermark and host programs. The true watermarks are protected against tampering. It increases the attacking difficulty, and the watermark can be efficiently protected.
-
Computer Engineering. 2008, 34(18): 199-201. https://doi.org/10.3969/j.issn.1000-3428.2008.18.071A reduction algorithm based on AdaBoost is proposed in the paper to reduce the intrusion feature redundancy. With algorithm, two classifiers——Ada weighted-classifier and Ada threshold-classifier are constructed, compared with support vector machine classifier. An Linux IDS experimental platform is designed and implemented, and the algorithm and three classification methods are applied using the platform. Experimental results show that intrusion feature set selected by the feature reduction algorithm is better, and the classification effect of Ada weighted-classifier and Ada threshold-classifier are better than SVM classifier, also the performance of detection Ada threshold-classifier is the best on test set.
-
Computer Engineering. 2008, 34(18): 202-203. https://doi.org/10.3969/j.issn.1000-3428.2008.18.072Modular inversion algorithm on GF(2m) is one of the most crucial algorithms in Elliptic Curve Cryptosystem(ECC). Under the analysis of a universal modular inversion algorithm, an improved algorithm is given in this paper. It can reduce many flaws of the universal algorithm, and has many good improvements for fast implementation. FPGA implementations for the improved algorithm on GF(283) and GF(2233) are presented and compared with two existing implementations respectively. The result indicates that the improved algorithm has about 72.9% higher efficiency on GF(283) and about 59.5% higher efficiency on GF(2233).
-
Computer Engineering. 2008, 34(18): 204-206. https://doi.org/10.3969/j.issn.1000-3428.2008.18.073This paper proposes a model of evaluating customer requirements and presents a method to evaluate customer requirements based on fuzzy sets and entropy. Fuzzy sets theory is used to represent customer requirements information. A competitive decision matrix is built, using entropy method to perform competitive analysis. It gives an online game example to illustrate this evaluating method, validating its efficiency and feasibility.
-
Computer Engineering. 2008, 34(18): 207-209. https://doi.org/10.3969/j.issn.1000-3428.2008.18.074A good modeling method for Multi-Agent System(MAS) is one of the necessary conditions for large-scale development and application of MAS. Nested Petri nets (NP-nets) as modeling tools are applied to Java Agent Development Framework(JADE), and a relationship of contrast between NP-nets and MAS which is based on object oriented programming is established. It not only can effectively restrict the scale of state space by using hierarchical structure, but also can overcome the tremendous difficulties of the structure evolution of Petri nets by nesting net token within others.
-
Computer Engineering. 2008, 34(18): 210-211. https://doi.org/10.3969/j.issn.1000-3428.2008.18.075This paper proposes an improved adapting algorithm to enhance the local search ability of particle swarm. The relationship between swarm average velocity and convergence is studied through numerical simulations. A novel inertia weight adjusting method is proposed. In this algorithm, inertia weight is adjusted dynamically according to the absolute average velocity which is the feedback information, and the average velocity is controlled to follow a given ideal velocity curve. Chaotic series is introduced in search to improve the local search ability of the algorithm. The experimental results of classic functions show that the improved hybrid method keeps the balance between the global search and the local search, and has great advantage of convergence property and robustness compared with PSO algorithm.
-
Computer Engineering. 2008, 34(18): 212-214. https://doi.org/10.3969/j.issn.1000-3428.2008.18.076This paper proposes a new patch-based sample texture synthesis algorithm based on Markov Random Field(MRF) model and other related algorithms. In the new algorithm, the min-cut algorithm of graph theory is adopted to optimize the likelihood of MRF and improves the scanning method from raster scanning to zigzag scanning. The new scanning method can restrain texel’s imperfection and texture’s orientation.
-
Computer Engineering. 2008, 34(18): 215-216. https://doi.org/10.3969/j.issn.1000-3428.2008.18.077Image segmentation is of great importance in the field of image processing. A wide variety of approaches have been proposed for image segmentation. Among them, Fuzzy C-Means (FCM) is a classic one. There are some disadvantages in FCM. A method of image segmentation based on information bottleneck is proposed. This agglomerative information bottleneck method is applied to cluster image pixel. In the process of image segmentation, Bayes Information Criterion(BIC) is used to determine the number of image region class. The system has been implemented and tested on an image database of about 500 images. Experimental results show good segmenting performance of this method.
-
Computer Engineering. 2008, 34(18): 217-219. https://doi.org/10.3969/j.issn.1000-3428.2008.18.078This paper develops a new Agent-Oriented Programming(AOP) language called IG-AOP with individual and group mental states by introducing group mental states into GOAL, and gives its syntax and semantics. Several desired properties of the language are introduced, and it is proved that the IG-AOP expresses better than GOAL through the example. The gap between theory and practice of Agent research is bridged, and taking into account of group mental states makes this language more suitable for solving the problem of multi-Agent cooperative modeling and concurrent programming.
-
Computer Engineering. 2008, 34(18): 220-222. https://doi.org/10.3969/j.issn.1000-3428.2008.18.079Aiming at the problems of getting the optimal mosaic image that only according to the evaluation value for the smoothness near the seam in mosaic resultant image by Spatial Frequency Activity(SFA) and based on the difficulty in evaluating the mosaic image used the traditional image quality evaluation methods, this paper uses Structural Contrast Degree(SCD) to evaluate the harmony of the mosaic resultant image in light of the contrast sensitivity of the visual perception property, and combines SFA and SCD to construct comprehensive mosaic image evaluation model so as to get the ideal mosaic image accorded with the subjective visual perception greatly. The validity of the visual perception model is proved by experiments.
-
Computer Engineering. 2008, 34(18): 223-225. https://doi.org/10.3969/j.issn.1000-3428.2008.18.080The current election systems or ballot recognition algorithms simplify layout understanding, and can not be applied to different kinds of ballots. Based on layout segmentation, this paper presents a description method of layout structure based on undirected graph, which makes location correctly and batch counting fast according to various ballot forms. Experiment shows that the method is agile, accurate, general and fast.
-
Computer Engineering. 2008, 34(18): 226-227. https://doi.org/10.3969/j.issn.1000-3428.2008.18.081Based on the theory of Artificial Neural Network(ANN), a three-layer Back Propagation(BP) network is proposed. The idea is to forecast medium and long term load by using the ability of ANN to nonlinear system factors. Some economic factors are selected as inputs for the BP ANN model. Variance contribution method is used for the optimization selection of correlative factors, and forecasting accuracy is discussed. Simulation results show that the method is feasible.
-
Computer Engineering. 2008, 34(18): 228-230. https://doi.org/10.3969/j.issn.1000-3428.2008.18.082To provide open multi-disaster geo-disaster data interface, intelligent unattended geo-disasters monitor terminals based on the embedded technology is constructed. For real-time monitoring geo-disasters, these monitor terminals can make up distributed network through wireless communication, and send the monitor data to monitor center. The geo-disaster forecast result is issued to the Internet through Web GIS by B/S structure, and offers open distributed remote issue of geo-disasters.
-
Computer Engineering. 2008, 34(18): 231-232. https://doi.org/10.3969/j.issn.1000-3428.2008.18.083To improve the agility and independency of experimental infrared camera, a portable infrared camera is built based on embedded technology. This camera can work without an assistant computer, because it has its own microprocessor, storage device, display device and input device. A Field Programmable Gate Array(FPGA) chip is used to generate the timing of infrared sensor and A/D converter. An ARM9 microprocessor chip, ported with Linux operating system, acquires the image data from FPGA, displayes the infrared image in a Liquid Crystal Display(LCD) and saves the data to a SD card. A touchscreen works as an input device to receive the user’s control instruction.
-
Computer Engineering. 2008, 34(18): 233-234. https://doi.org/10.3969/j.issn.1000-3428.2008.18.084In order to supply a gap in automatization of load and unload production on parking apron, this paper presents a PDA-based loading production system which connects to Internet by GPRS. It can accomplish all of scheduled flight load, unload, hand-over, dynamic cabin-adjust and unload-check operations by communicating with Tang system, thus can change the traditional manual work mode and greatly improve the load-unload efficience.
-
Computer Engineering. 2008, 34(18): 235-236. https://doi.org/10.3969/j.issn.1000-3428.2008.18.085The Eclipse Modeling Framework(EMF) and Graphical Editing Framework(GEF) technologies based on Eclipse are used to design a simulation-flow workbench for mechanical product and some achievement is obtained. The two technologies as well as their development and realization process are introduced. In order that GEF can use the models generated by EMF, command stack of the two technologies are harmonized. Simulation-flow modeling of mechanical product is accomplished using the editing tool developed by EMF and GEF.
-
Computer Engineering. 2008, 34(18): 237-238. https://doi.org/10.3969/j.issn.1000-3428.2008.18.086This paper discusses how to design one kind of embedded system according to the interface of vehicle reinforced computer, describs the design requirement, function block and software flowchart. It provides new idea for testing the interface of vehicle reinforced computer. The equipment designed provides some kinds of interface that is used normally in vehicle reinforced computer, and it has the benefit of simple made up, convenient usage, low cost, and can replace all kinds of discrete cards that are used in test before.
-
Computer Engineering. 2008, 34(18): 239-242. https://doi.org/10.3969/j.issn.1000-3428.2008.18.087Recently, attentions are focused more on vehicle interior network application and the wireless vehicle-carry data transmission technology. For developing a remote monitoring system, three aspects of the system are discussed: the vehicle interior network configuration, the CAN/GPRS gateway realization and the remote monitoring server design. Described in the paper are hardware design, programming of low level drivers, the network application layer protocol design, the ARM-Linux transplant and the protocol conversion. Contents include GPRS wireless networking and socket communication.
-
Computer Engineering. 2008, 34(18): 243-245. https://doi.org/10.3969/j.issn.1000-3428.2008.18.088How to use Model Driven Architecture(MDA) in building GIS application, this paper analyzes the architecture and core technologies of MDA, and then give a method of building GIS domain model, transferring model and developing application. This method improves the efficiency of software development, strengthens the interoperability, transplantation, platform-independent and maintenance of GIS system.
-
Computer Engineering. 2008, 34(18): 246-247. https://doi.org/10.3969/j.issn.1000-3428.2008.18.089Electronic whiteboard is an important tool for people to exchange information and capture the ideas. The existing whiteboard is powerful, but it is not according to the natural habit of using pen and papers. So it is urgent to research applications software for pen interaction. This paper designs and implements an electronic whiteboard system prototype. It describes the module structure and the method. Application indicates that the prototype system reflects the user-centered idea, and is in accordance with people’s daily lives, modes of communication.
-
Computer Engineering. 2008, 34(18): 248-250. https://doi.org/10.3969/j.issn.1000-3428.2008.18.090A new architecture is proposed to deploy IPv6 over DVB in distance education. This architecture includes three parts. The first one is management and distribution system of education resources, the second one is IPv6 over DVB transmission system, and the last one is deployment scheme. Education resources scattered in different areas are packed into IP packets and transmitted to 1 000 country elementary schools by these systems on satellite. The details are presented.
-
Computer Engineering. 2008, 34(18): 251-253. https://doi.org/10.3969/j.issn.1000-3428.2008.18.091Hierarchy model and interaction frameworks of intelligent user interface based on Multi-agent System(MAS) are proposed. The problems of multi-modal input information fusion and multimedia information presentation are solved by the chemical bond theory based on mutual information. The mobile pervasive access is disposed by the mechanism of chameleon based on environment awareness, and the cooperative and effective grid computing of peer-to-peer is implemented by using the economic market model and Web service technology. The definition of chemical abstract machine for dynamic interaction simulation of the system is given. The application example indicates that this framework can provide natural and high efficiency interaction pattern, and deduce the barriers between human and computer.
-
Computer Engineering. 2008, 34(18): 254-256. https://doi.org/10.3969/j.issn.1000-3428.2008.18.092Most computation in JPEG2000 is redundant and it has substantial impact on compression speed of satellite remote sensing image. Coding rate control algorithm truncation prediction of remote sensing image based on statistical model is proposed to alleviate this problem. The algorithm establishes statistical model to predict optimal rate-distortion slope as the threshold of tile1 encoding, and the threshold can be adjusted adaptively according to the length of encoded stream. An approximate optimal slope threshold is obtained, on the basis of which tile2 encoding searches for optimal rate-distortion slope and optimal truncation point to realize rate control. Experimental result shows that the proposed algorithm can effectively reduce the encoding time, and it is reduced by 40% at the 0.5 bpp bit-rate comparing with JasPer, while the PSNR of the reconstructed images almost is not reduced.
-
Computer Engineering. 2008, 34(18): 257-259. https://doi.org/10.3969/j.issn.1000-3428.2008.18.093T-Engine is an open standard platform for next generation real-time embedded system of ubiquitous computing system, which consists of standard hardware architecture T-Engine and standard open-source operating system kernel T-Kernel. It has excellent performance in executing speed and porting. This paper introduces the specifications of T-Engine hardware and software. An instance for the platform’s application in the area of embedded system development is given according to the design of a portable individual information searching system based on fingerprint recognition. The results show that the T-Engine platform meets the demands in system volume, power restrict and real-time requirement.
-
Computer Engineering. 2008, 34(18): 260-262. https://doi.org/10.3969/j.issn.1000-3428.2008.18.094By using the technologies of Tibetan online input on the Web, Tibetan characters can be input to a Web browser directly without using local input methods. It accomplishes the online character interaction of Tibetan language, and provides a cross-platform solution of Tibetan input method for a network system. This paper explains the basic design philosophies and the principles of online input technologies of Tibetan language which is based on the Web pages. It establishes the components of the online input method of Tibetan language, the principles to design internal and external codes and the flows of the input method. It applies a system analysis and provides a real model of Tibetan input method, and addresses the information technologies of Tibetan typeface which are embedded inside browsers to achieve online and real-time inputs of Tibetan language. It also implements the combination between online input technologies of Tibetan and main webpage editors by using embedded and external methods.
-
Computer Engineering. 2008, 34(18): 263-265. https://doi.org/10.3969/j.issn.1000-3428.2008.18.095The memory system is the performance bottleneck while general processor handles stream applications. Based on the FT64 stream architecture, this paper presents a structure design method and data transfer mechanism of the stream register file which is oriented to stream application, and analyzes the effect on FT64. This structure with the adoption of big capacity, high bandwidth and multiple virtual ports can limit most of the stream data access operation at the register file level, greatly decrease the pressure of the main memory. Experimental result shows this structure meets the demand of stream applications.
-
Computer Engineering. 2008, 34(18): 266-268. https://doi.org/10.3969/j.issn.1000-3428.2008.18.096This paper uses Bayesian network to model operational risk of bank that is difficult to model and measure. Operational risk is the risk resulting from inadequate or failed internal processes, people and systems or from external events. After reviewing operational risk of bank and Bayesian networks, this paper illustrates how to use Bayesian networks to manage operational risk by examples, including measure risk, casual modeling, scenario analysis and etc. This paper also gives a Bayesian network model framework of operational risk.
-
Computer Engineering. 2008, 34(18): 269-271. https://doi.org/10.3969/j.issn.1000-3428.2008.18.097Based on the analysis of a military C4ISR’s demand, the overall project based on HLA is designed. The implementation method of federates combined with software and hardware is disscussed, and the design of OMT is introduced. The implementation procedure of federation is presented, and the instance of putting all the federates into the federation is given. The results show this operational simulation system meets the demand of military training well.
-
Computer Engineering. 2008, 34(18): 272-273. https://doi.org/10.3969/j.issn.1000-3428.2008.18.098This paper discusses how to display the map of the major hazard information system using SVG technology. This system makes use of the SVG’s advantages of describing the vector graphics. A descriptive model of map symbol based on SVG is presented. It describes the general points, lines and regions, depending on which, most of the entity objects in map are displayed. The storing method of space data in digital map is implemented by using the characteristics of SVG based on XML. This method sets up an efficient relationship between the space data and the attribute data.
-
Computer Engineering. 2008, 34(18): 274-277. https://doi.org/10.3969/j.issn.1000-3428.2008.18.099It is an important research issue to establish a high level architecture model for design space exploration of RC(Reconfigurable Computing). A hierarchical parameter model for two dimensions array based on RC is presented in this paper, which is organized by four levels, top description struction, function module description struction, unit description struction and function description struction. With taking no account of architecture details, this paper describes architecture characteristic of RC in high abstract level. Application examples show that it has high flexibility and good hierarchy, and it is efficient to characterize two different dimensions array based on RC.
-
Computer Engineering. 2008, 34(18): 278-280. https://doi.org/10.3969/j.issn.1000-3428.2008.18.100Based on embedded file system Compact Flash File System(CFFS) which is oriented for large-scale NAND flash chips, this paper proposes a fast mounting mechanism. The mechanism uses the data structures such as “static super block”, “reference node”, “page bit map” and adopts some corresponding algorithms, soit avoids the full scanning of the flash chip when the file system is being mounted. Test shows that the mechanism can reduce the mounting time significantly when the file system is mounted on large-scale NAND flash chips.
-
Computer Engineering. 2008, 34(18): 281-282. https://doi.org/10.3969/j.issn.1000-3428.2008.18.101This paper introduces a new way in which factor analysis combines with Borda fuzzy math method to build the e-government comprehensive evaluation model. The influence of the relevance among the indexes is dispelled by the former method and the evaluation indexes are reduced. The evaluation model is built by the latter method and the former method’s shortage that the evaluated result is easily influenced by single appraisal factor is remedied. Case study shows that the comprehensive evaluation result by the model based on above-mentioned methods is more nearer to the truth.
-
Computer Engineering. 2008, 34(18): 283-285. https://doi.org/10.3969/j.issn.1000-3428.2008.18.102This paper presents a prototype system, ontoWeather, based on research in semantic query. The ontology library of the strong convection in meteorology and the reasoner rules in this domain are set up by this system. Semantic query on domain is implemented by applying with Jena and gets the relative semantic results. This system improves the accuracy and completeness of the query on meteorology.
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