20 August 2008, Volume 34 Issue 16
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Computer Engineering. 2008, 34(16): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2008.16.001It is an important problem for P2P file sharing system to limit sharing illegal contents. Maze introduces a filtering strategy based on file popularity and active peer. Simulation experiments show that the technology can decrease the download of illegal files, and save network resource consumption. It is simple but rather practical, reflecting the idea to deal with key problem first in the large-scale system.
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Computer Engineering. 2008, 34(16): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2008.16.002This paper proposes a novel verification method based on the neighborhood competing models. The method can improve the performance of likelihood ratio verification method in mismatch conditions by incorporating robust neighborhood information for a target model. Compared with traditional Likelihood Ratio Test(LRT) and On-line Garbage(OLG) model verification methods, experiments show the method can provide a comparable performance to the original LRT method in clean environment, but outperform the other approaches in the Gaussian white noise condition with Equal-Error-Rate(EER) reduced by 1.2% and 4.2%, and it also achieves better verification performance in other noise conditions.
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Computer Engineering. 2008, 34(16): 7-9. https://doi.org/10.3969/j.issn.1000-3428.2008.16.003This paper proposes a CSD-based architecture namely CDA for computing inner product when one of the input vectors is fixed, and designs 2-D Discrete Cosine Transform(DCT) architecture with it. By optimizing the transform matrix, it reduces the number of the adders and the band of the shifter/adder. It is designed and synthesized by Chartered 0.13 μｍ technology, and its cost is 31 528 transistors and 1 024 bit memory. Because the architecture is with low power and high performance, it is useful for image/video compression and transmission applications.
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Computer Engineering. 2008, 34(16): 10-12. https://doi.org/10.3969/j.issn.1000-3428.2008.16.004The key problem in the reverse analysis of encrypted Programmable Logic Devices(PLD) using logic analysis techniques is to collect effective and self-contained data set, especially for timing PLD. An efficient data collecting algorithm is presented whichs suit for large scale and multi-state synchronous PLDs. The algorithm builds non-complete state graph and finds the shortest path for state migration form initial state to each effect state. The algorithm has ideal time and space cost and has been used in the PLD reverse engineering system.
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Computer Engineering. 2008, 34(16): 13-15. https://doi.org/10.3969/j.issn.1000-3428.2008.16.005This paper adopts a strategy of fitting offset to adjust time, to conquer the impact of network delay and jitter on clock synchronization effectively. The paper makes three major contributions to this research area. Client software of clock synchronization is developed by this project, and it can collect and save all kinds of time stamps. The paper analyzes the local time of slave node and the arrival timestamps, from the reference server, to create offset trend equation, adopts a method of linear fit to create a mathematic model of clock drift rate, and uses this drift rate to adjust time and analyze stability. Result proves that it not only can improve the stability and security of clock synchronization on client, buyalso has better adaptability to clock synchronization on worse environment of network transport.
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Computer Engineering. 2008, 34(16): 16-18. https://doi.org/10.3969/j.issn.1000-3428.2008.16.006Aiming at the quality of XML data, this paper introduces a metadata model based on XML cleaning data through Bayes learning method and Markoff chain probabilistic strategy, and designs a new intelligence method how to clean XML data by the idea which can clean the similarity duplicated records. Compared with other methods, experimental results show that it not only has a high automatization and a low manual working, but also has a better precision and its recall rates between 2% and 5%.
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Computer Engineering. 2008, 34(16): 19-21. https://doi.org/10.3969/j.issn.1000-3428.2008.16.007To deal with resource constrained stochastic job scheduling problem, a discrete-time job during distribution stochastic project scheduling problem subject to an incompatibility constraint and multiple renewable resource constraints is described by a discrete-time discrete-event dynamic system. The objective is to minimize the expected project duration under the resource and job order constraints. The optimal solution can be obtained by solving a stochastic dynamic program. The solution modeled as a Markov decision process is described in detail. A typical example validates the feasibility of the method.
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Computer Engineering. 2008, 34(16): 22-24. https://doi.org/10.3969/j.issn.1000-3428.2008.16.008The roles of user are assigned by administrators in Role-based Access Control(RBAC) system. This method is complicated and fallible in a large system, so an automatic User-Role Assignment(URA) model is proposed based on attribute and security context constraints, and an Automatic URA(AURA) algorithm is presented, which realizes the model of AURA. It ensures flexibleness and security of systems, and provides convenience for application of RBAC in large systems.
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Computer Engineering. 2008, 34(16): 25-27. https://doi.org/10.3969/j.issn.1000-3428.2008.16.009A location-based Adaptive Real-Time Routing Protocol(ARTRP) is proposed on the ground that each node in wireless sensor network possesses some problems, such as energy conserving, limited bandwidth, and so on. In order to meet different levels real-time requirement for different applications and improve the energy efficiency, this protocol automatically adjusts data packets transmission rate at different times, selects the optimal flow paths. On the OMNET++ software platform, simulation results show that it increases the real-time characteristic, data packet arrival rate and network lifetime.
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Computer Engineering. 2008, 34(16): 28-30. https://doi.org/10.3969/j.issn.1000-3428.2008.16.010The attributes core of a decision table is the start point to many existing algorithms of attributes reduction. In order to solve the inconsistent data problem, A new discernibility matrix definition based on Dominance based Rough Set Approach(DRSA) and the computation of core is proposed, but it is too complex. An improved discernibility matrix definition with a method for computing the core is introduced, which can get the right core with low space and time complexity. Experimental results prove the effectiveness of the algorithm, and it suits the large data.
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Computer Engineering. 2008, 34(16): 31-33. https://doi.org/10.3969/j.issn.1000-3428.2008.16.011In flexible stack system, stack master and stack slave are all in working state, the process priority of data batch synchronization is not the highest, it is very difficult to synchronize data quickly and reliably between stack master and slave. This paper presents a method for data batch synchronization, with the help of message channel detection and sequence number confirmation, which can improve the efficiency and reliability, and it can run quite well in a real-time operating system.
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Computer Engineering. 2008, 34(16): 34-36. https://doi.org/10.3969/j.issn.1000-3428.2008.16.012Focusing on state transfer between components in dynamic update, an approach that can dynamically update objects is proposed and the so-called modification spread without modifying JVM is prevented. On basis of the mechanism of JVM’s class loading and reflection, an experimental system which implements state transfer is designed.
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Computer Engineering. 2008, 34(16): 37-40. https://doi.org/10.3969/j.issn.1000-3428.2008.16.013New concepts such as data flexibility, data flexibility analysis method, and some other related ones are presented. To well solve the key problem of how to adapt the variation conversion for the user’s data structure, a Data Flexibility Hierarchical Model(DFHM) and a Flexible Data Access Model(FDAM) are proposed and established by introducing meta-data. During the analysis of data flexibility and model building, a new software design method is proposed, for which meta-data is the kernel. The presented data flexibility theory and related method are successfully applied into a series of flexible software development for the information system and adopted by the software engineering practice, which gain excellent social and economic benefits.
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Computer Engineering. 2008, 34(16): 41-43. https://doi.org/10.3969/j.issn.1000-3428.2008.16.014Because of the limitations of the previous modeling methods, this paper combines the ideas of the discrete modeling to propose the whole trajectory model, which is on the basis of the Moving Objects Spatio-Temporal(MOST) model and supports the past, present and future information processing. Adopting the linear interpolation of the point-based modeling method, the MOST model disposes the historical information. It can query the present and near future information. However, it adopts the efficiently predicted-speeds to dispose the further future information queryings. Experiment shows the comparison results of three predicted-speeds and two location update policies of the whole trajectory modeling.
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Computer Engineering. 2008, 34(16): 44-46. https://doi.org/10.3969/j.issn.1000-3428.2008.16.015Software pipelining is used to improve the performance of programs in IA-64, but the codes generated are relevant to the hardware plat, which makes them difficult to be migrated between different platforms. This paper analyzes the software-pipelined mechanism of IA-64, and presents two methods to eliminate software pipelined codes from optimized IA-64 executables. These two methods can convert the software pipelined codes into semantically equivalent sequential counterparts without dependence on the hardware. Experiments verify the validity of the proposed methods.
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Computer Engineering. 2008, 34(16): 47-49. https://doi.org/10.3969/j.issn.1000-3428.2008.16.016This paper presents a new ranking algorithm for semantic Web services discovery process, which adopts the notion of rewriting for ranking among candidate semantic Web services. Experimental results verify that this algorithm is efficient and has low time cost and can efficiently facilitate user’s decision and semantic Web services platform’s automatic computation.
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Computer Engineering. 2008, 34(16): 50-52. https://doi.org/10.3969/j.issn.1000-3428.2008.16.017The set of frequent closed patterns uniquely determines the complete set of all frequent patterns. According to the features of data streams, a new algorithm is proposed for mining the frequent closed patterns. The data streams are partitioned into a set of segments, and a DSFCI_tree is used to store the potential frequent closed patterns dynamically. With the arrival of each batch of data, the algorithm builds a corresponding local DSFCI_tree, then updates and prunes the global DSFCI_tree effectively to mine the frequent closed patterns in the entire data streams. The experiments and analysis show that the algorithm has good performance.
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Computer Engineering. 2008, 34(16): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2008.16.018Change capture and synchronization strategy are two major issues for data synchronization in distributed applications. On analyzing main insufficiencies of schemes hitherto, a common efficient trigger-based method of change capture is proposed, and a corresponding synchronization strategy across DBMS such as Oracle, Sybase, and MS SQL Server is designed and implemented. Theoretical analysis and experiments justify the method and strategy for practical data replications between these main commercial heterogeneous databases while still holding the autonomy of client systems and the availability of data.
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Computer Engineering. 2008, 34(16): 56-59. https://doi.org/10.3969/j.issn.1000-3428.2008.16.019In order to improve the process of concept lattice to the uncertain formal context, based on the analysis of the existing concept lattice and its improved model, cloud model is introduced into the research of concept lattice. A novel lattice is proposed, which is called cloud concept lattice, this lattice unifies binary and multi-valued context, uncertain and certain context. And qualities of cloud concept lattice are proved. Application in data mining is discussed. Based on cloud concept lattice, a novel algorithm of association rule mining is proposed with an example.
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Computer Engineering. 2008, 34(16): 60-62. https://doi.org/10.3969/j.issn.1000-3428.2008.16.020Mobile database system adopts optimistic replication mechanism because of its characteristics. This article introduces the concept of union-transaction, presents Union-Transaction Division Algorithm(UTDA) and Conflict Reconciliation Algorithm(CRA). UTDA algorithm divides mobile transactions in mobile terminal into union-transactions, makes union-transaction as basic granularity of data synchronization and conflict reconciliation. Experimental results show that UTDA algorithm satisfies atomic and serializability of transaction execution. The cost of commit time falls by two-third approximately. It provides a kind of feasible scheme for conflict reconciliation of mobile database system.
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Computer Engineering. 2008, 34(16): 63-65. https://doi.org/10.3969/j.issn.1000-3428.2008.16.021The problem of processing streaming XML data is gaining widespread attention from the research community. This paper proposes a novel algorithm for handling of multiple queries over the XML streams. The approach merges the multiple queries into a single prefix sharing query tree, and combines the automata with the runtime stack structure to answer multiple XML path queries through scanning the XML stream at the same time. The algorithm returns the whole matching path by using a new hierarchical stack structure to store the result of query pattern matches, and confirms the relationship within the node through the position encodes in the XML data stream.
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Computer Engineering. 2008, 34(16): 66-68. https://doi.org/10.3969/j.issn.1000-3428.2008.16.022This paper analyzes the state of the art and existing problem of Quality of Service(QoS) and its estimation, and a reference matrix for QoS is given out. A new QoS model which includes service time, service cost, integrity, availability, and reputation is put forward from accurate and flexible view. In this model, a new method for QoS estimation is presented. This method which collects quality information from users is used to calculate the QoS using a kind of fuzzy method for QoS estimation based on the QoS requirement of users. Its correctness and feasibility is indicated through experimental analysis.
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Computer Engineering. 2008, 34(16): 69-71. https://doi.org/10.3969/j.issn.1000-3428.2008.16.023Reverse Nearest Neighbor(RNN) queries are of activity area in spatial database. However, most of the traditional algorithms find the RNN in the whole data set. This paper combines constrained relationship with RNN queries and some methods are proposed. It also gives some ways to solve the problem of Constrained Reverse Nearest Neighbor(CRNN) with the internal relationship between Nearest Neighbor(NN) queries and RNN queries. As is shown by the experiments, this algorithm can improve the query efficiency compared with the traditional ones.
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Computer Engineering. 2008, 34(16): 72-74. https://doi.org/10.3969/j.issn.1000-3428.2008.16.024Workflow pattern mining is a new research area in data mining. Workflow schema which is effectively applied to business requirement modeling and business process reconstruction can be mined from certain execution logs. A method of Logs-Based Workflow Mining(LBWM) is proposed to implement workflow schema mining based on algebra of partial order and triangular optimization rules. Experiments show that scanning the execution logs once and good workflow pattern can be obtained in linear time. The result includes the original workflow and has high completeness, while the coverage rate of the logs is not the main influencing factor. The result gets higher consistency with the original workflow pattern when the coverage rate of the logs is higher.
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Computer Engineering. 2008, 34(16): 75-76. https://doi.org/10.3969/j.issn.1000-3428.2008.16.025To improve the safety and reliability of software, a method to detect and analyze software faults is introduced. This method uses the static analysis of programs to locate faults, and uses fault tree to find the source of those faults. Invalid arithmetic operation is a common kind of error in programs, which often causes the system collapse. An invalid arithmetic fault analyzing process is discussed as an example to illustrate the analyzing process. This method is proved in experiment to be effective in locating and analyzing faults.
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Computer Engineering. 2008, 34(16): 77-79. https://doi.org/10.3969/j.issn.1000-3428.2008.16.026Commercial Off-The Shelf(COTS) component evaluation and selection is a key step in COTS-based software development. A new method for COTS evaluation and selection based on Gap analysis is proposed. The gap of functionality between COTS and requirements and corresponding adjustment cost are measured in function point model. The fitness of COTS to requirements is defined as the ratio of the software size of target system to the total “cost” of COTS that is also measured in software size. An example with hypothetical data is used to demonstrate the proposed approach.
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Computer Engineering. 2008, 34(16): 80-81. https://doi.org/10.3969/j.issn.1000-3428.2008.16.027There are perhaps different configuration files in the terminals in distributed configuration system. This paper designs a configuration file Distributed Lock based on the assembled system. It uses incompatible method to revision configuration files, and keeps the coherence of configuration files in all the terminals. Activation data packet is used to avoide the receiving request being blocked blocked, and to keep the reliable and stability of all the system.
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Computer Engineering. 2008, 34(16): 82-84. https://doi.org/10.3969/j.issn.1000-3428.2008.16.028This paper analyzes the problems from the applying of traditional C/S computing model in mobile computing environment, and puts forward models for accessing remote database based on Mobile Agent(MA) according to the kind of mobile application. The principle and method of this model is discussed, and realization algorithm is given. It summarizes the model characteristic according to the application. Practical results show that the model is suitable for the mobile computing environment and has high correctness.
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Computer Engineering. 2008, 34(16): 85-86. https://doi.org/10.3969/j.issn.1000-3428.2008.16.029In conventional Hash algorithms, the overflow buckets are linked with not only main bucket but also overflow bucket by the pointer. It is inefficient to search a value corresponding to a overflow bucket. This paper presents a novel dynamic Hash indexing structure called DL tree which uses B+tree structure to describe bucket address table, and establishes a B+tress between the bucket address table and register key assignments. The bucket element can be found by dimidiate research. The experimental results show that its comprehensive performance is better than other indexing algorithm. It can improve 15% of the equivalent inquiry efficiency.
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Computer Engineering. 2008, 34(16): 87-88. https://doi.org/10.3969/j.issn.1000-3428.2008.16.030In the distributed database system, distributed inquiry process becomes more difficult and complex because of the physical distribution and redundancy of data, which makes the optimized inquiry method based on distributed database system become one of the cores of the database query theories. This paper uses XML to analyze the user’s non-recursive query assignments to obtain the smallest query view, queries to each distributed database, and returns the results of the query to the user to realize the effective query to the distributed database.
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Computer Engineering. 2008, 34(16): 89-91. https://doi.org/10.3969/j.issn.1000-3428.2008.16.031To decrease the data generated by serialization, this paper uses grid-based PDE.Mart as platform, investigates different service types of Apache AXIS, compares the amount of data generated by different serialization protocols like SOAP serialization, Base64 serialization and byte stream serialization before and after compression. A hybrid approach that combines byte stream serialization and compression technology is proposed, which can significantly decrease the data being transferred in the grid, so as to improve performance of data transfer and enable grid computing system to solve large scale problems.
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Computer Engineering. 2008, 34(16): 92-94. https://doi.org/10.3969/j.issn.1000-3428.2008.16.032With a traditional text search engine which is based on Lucene, this paper describes a semantic search experimental system which uses C/S pattern. In the system, user sets the configuration which will be passed to the server according to user’s wants, and the server operates the query keywords which is submitted by user with ontology navigation and synonym searching according to these configuration, enters these optimized query keywords into traditional text search engine for searching the result, and returns these results to client in the order defined by user. This system uses the interaction between the client and the server, and query expanding trying to raise rate of precision and recall of the retrieval system.
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Computer Engineering. 2008, 34(16): 95-97. https://doi.org/10.3969/j.issn.1000-3428.2008.16.033In order to eliminate redundant communication generated in data collection of automatic program parallelization, array last-write relation analysis is proposed to implement fast computation of array data last-write relation in loop nest, whose result is necessary condition for generating accurate data collection code in backend of compiler. This paper describes the aim and content of array last-write analysis, sorts the loop nests into different types according to their construction characteristic, and presents the algorithm implementation process in detail for each type. The test result shows the high performance and accuracy of the algorithm. And the accurate data collection code can efficiently eliminate part of redundant communication, which optimizes the parallel programs.
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Computer Engineering. 2008, 34(16): 97-98. https://doi.org/10.3969/j.issn.1000-3428.2008.16.034In SOA application flow, it is hard for service user to bind high performance services. Based on the load sharing strategy and the model of Web service quality evaluation, Dynamic Web Service Binding(DWSB) algorithm is presented. The DWSB algorithm first chooses the higher QoS rank services set, and uses the round robin algorithm to select a non-overload service as the best service from the set. Experimental results show that it is useful for the DWSB algorithm to help service user find high performance services.
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Computer Engineering. 2008, 34(16): 99-101. https://doi.org/10.3969/j.issn.1000-3428.2008.16.035This paper provides the best relationship between the transmission distance and the deploy density of the nodes to prolong the survivable time of the whole network. It analyzes the distance between nodes under ideal conditions when every pair of the nearby nodes has the same distance. In an area of 100 m ×100 m deployed by 1 000 nodes, the best distance of nodes is 3.92 m Simulation results in the condition of stochastic deployment are given. The best transmission distance is from 4 m to 6 m which meets the calculation To overcome the problem of network partition and useless transmission, feedback algorithm and appropriative cluster head are introduced to reduce the energy consumption while ensuring data sending. The method can increase the survivable time of network and can recover while some nodes fail.
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Computer Engineering. 2008, 34(16): 102-104. https://doi.org/10.3969/j.issn.1000-3428.2008.16.036The external interactive satellite communication system is a competitive solution for remote education in China. Based on the analysis of the external interactive communication, a new scheme of external interactive satellite communication systems in the network layer is proposed. Details of the system architecture, data processing procedure and key units are also included. Field experiments show that such a system can support both broadcasting and interactive services, which makes it highly flexible and prospective in the applications of distance learning and broadband access network in remote areas.
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Computer Engineering. 2008, 34(16): 105-106. https://doi.org/10.3969/j.issn.1000-3428.2008.16.037Based on the phase space reconstruction improved by wavelet transformation, this paper takes influence of wavelet denoising into account, and introduces the method of chiastic time series predictor based on wavelet neural network traffic flow prediction. Experimental results show that, comparing with RBF neural prediction method, wavelet neural network prediction method approaches better result, and the error margin is smaller.
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Computer Engineering. 2008, 34(16): 107-110. https://doi.org/10.3969/j.issn.1000-3428.2008.16.038The synchronization of forwarding table between control plane and forwarding plane is an important factor that influences the data forwarding reliability and the scalability. By analyzing the structure and the logical relationship of each functional entity in distributed router, this paper proposes a fast synchronization method of forwarding table named RIMcast, and gives a macroscopical design. It is indicated that RIMcast has good delay characteristic for multiple interface card of distributed router from the analysis of theoretic mathematical model and simulation about RIMcast.
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Computer Engineering. 2008, 34(16): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2008.16.039In design of large-scale access convergence router(hereafter referred to ACR) forwarding engine, the Xilinx Virtex-4 FPGA’s RocketI/O multi-gigabit transceiver is used to satisfy the need of high speed and steady interface between forwarding engine and switch fabric. This paper proposes an assistant channel bonding method for solving the difficult problem of channels-bonding synchronization. Experimental results show the method is effective.
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Computer Engineering. 2008, 34(16): 114-115. https://doi.org/10.3969/j.issn.1000-3428.2008.16.040Refering to the dynamic load change in the Web server cluster system, this paper presents a new load balancing algorithm to achieve more efficient balance of the task allocation. Combined with dynamic feedback algorithm theory, the algorithm changes the corresponding nodes weight according to the load of server node periodically, avoiding the server load imbalance. Experimental results show that the algorithm effectively reduces the average system latency, improves the throughput, and enhances the overall cluster system performance.
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Computer Engineering. 2008, 34(16): 116-118. https://doi.org/10.3969/j.issn.1000-3428.2008.16.041Based on the research of the most fashionable projects of multi-pattern matching, this paper proposes an improved multiple patterns matching algorithm. This algorithm realizes that TCAM can perform parallel search at high speed. Furthermore, the improved algorithm achieves the shift-acceleration of patterns and flexibly controls the step length. This is the reason that the average shift-step is highly increased. Experimental results show, if the width of TCAM is 8 Byte, the average step length increases from 1 Byte to 5 Byte, the matching speed increases from 2 Gb/s to 10 Gb/s.
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Computer Engineering. 2008, 34(16): 119-121. https://doi.org/10.3969/j.issn.1000-3428.2008.16.042Data delivery can be easily interrupted by departure of end hosts in P2P live streaming network, which may lead to degradation of QoS in time-sensitive applications. This paper proposes a new layered and clustering protocol. Based on user behavior analysis in live streaming, it can keep a level of efficiency while reduce the interruption times of Application Layer Multicast(ALM) tree. Simulation results show that the protocol can effectively boost up the robustness, reduce the average ALM latency, and satisfy the scalability.
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Computer Engineering. 2008, 34(16): 122-124. https://doi.org/10.3969/j.issn.1000-3428.2008.16.043For the exist content-based Publish/Subscribe(P/S) systems, general peer-to-peer topology can not support subscription covering, on the base of absorbing their design ideas, with reverse path forwarding technique and dynamic receiver update and partition strategy, a new route algorithm for content-based P/S system which supports general cyclic topology and subscription covering is proposed. Analysis shows that the algorithm can completely meet the requirement of P/S system of cyclic topology, the new route algorithm also guarantees that all the subscribers have subscription matched the event will receive the event without routing loops.
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Computer Engineering. 2008, 34(16): 125-128. https://doi.org/10.3969/j.issn.1000-3428.2008.16.044A domain communication mechanism for Mobile Agent(MA) based on mailbox is presented. Mailbox mechanism can decrease the probability on a chase issue, mailbox synchronization transfer improves system dependability, and a domain partition in reason reduces the MA system addresses costs and communication costs. Analysis and real experiment indicate that the communication mechanism for MA enhances location transparency and improves efficiency of the system.
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Computer Engineering. 2008, 34(16): 129-131. https://doi.org/10.3969/j.issn.1000-3428.2008.16.045Feedback control load balancing algorithm is proposed to solve the problem that cluster render system can not implement dynamical load balancing when it treats with multistage task. The idea of feedback control is introduced and the principle of load balancing is referred in this algorithm which uses the strategy of centralized load balancing to schedule and allot task-thread and provides response time guarantees for different services and implements load balancing through adjusting load of all nodes of cluster render system real-timely and dynamically. Experimental results show the whole performance of this system improves 1/3 than the old one’s and proves the validity and feasibility of this algorithm.
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Computer Engineering. 2008, 34(16): 132-134. https://doi.org/10.3969/j.issn.1000-3428.2008.16.046This paper optimizes the traditional scheme to ensure the peak service of hot video objects by researching the clients’ accessing pattern to popular video objects, and designs a high performance cluster video server to ensure the peak service of hot video objects. It discusses the architecture and module functionality of the system, and provides the processing of software implementation. Test results show that the hot video concurrent threshold between 80 and 100 is appropriate.
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Computer Engineering. 2008, 34(16): 135-137. https://doi.org/10.3969/j.issn.1000-3428.2008.16.047Based on the comprehensive use of J2EE, J2ME, UML and MVC technology, this paper proposes a common phone network game system framework, and discusses the relevant elements in designing the framework. This system uses the MVC framework structure and also uses the UML to build the phone model between the server and the client. By using the development technology of J2ME phones and J2EE server, the certification of a common mobile game framework is presented through a specific applications in mobile network games. Practices show this system is effective.
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Computer Engineering. 2008, 34(16): 138-140. https://doi.org/10.3969/j.issn.1000-3428.2008.16.048Study of system architecture is the base of design and implementation of any practical system. This paper defines the survivability architecture and correlation concepts of network information system and principles, analyzes the run mechanism of survivability systems and explains the effect of survivability specialties. The survivability architecture of 3+2 model is presented. Practices show the architecture is effective.
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Computer Engineering. 2008, 34(16): 141-143. https://doi.org/10.3969/j.issn.1000-3428.2008.16.049With the development of wireless sensor networks technologies, network model tends to be dynamic, nodes in networks become mobile. It brings new challenges to routing algorithms. This paper introduces the Dynamic Leaves Tree(DLT) network model, presents the DLR routing algorithm used in the dynamic network without localization information. The DLR routing algorithm includes path-similarity computation and optimal path selection. Simulation results show that the DLR routing algorithm can guarantee more than 90% communication reliability in dynamic networks.
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Computer Engineering. 2008, 34(16): 144-146. https://doi.org/10.3969/j.issn.1000-3428.2008.16.050For contention resolution in OBS, this paper proposes a new priority-based Grouping and Hybrid-Assembly(GHA) policy, which is combined with head-dropping and deflection routing scheme. Simulation results demonstrate that this policy reduces packets loss probability, especially the packets with high priority, so that, it can be well used in the optical burst switched networks with QoS requirement.
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Computer Engineering. 2008, 34(16): 147-149. https://doi.org/10.3969/j.issn.1000-3428.2008.16.051Following the analysis of the feature of network simulation tool NS-2, this paper proposes the establishment of Ad Hoc network distributed CA model emulation and the design techniques of packet, application layer protocol, transport layer protocol and timer. Through the modification of the existed data structure and the addition of new network modules, NS-2 functionality is extended to cope with the emulation of Ad Hoc network distributed CA. Based on these techniques, the network performance of Ad Hoc network distributed CA model can be effectively analyzed, which will provide sound evidence for the design and evaluation.
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Computer Engineering. 2008, 34(16): 150-152. https://doi.org/10.3969/j.issn.1000-3428.2008.16.052Motivated by high-performance computing, this paper proposes a modular ligthweight mobile agent model. In the way of strategy distribution and assembly, this model realizes production reconfigurable migration, and achieves the goal of lightweight. Based on exsiting mobile semantics, advanced from practice, regarding direct communication between agents as channel, this paper puts forward formal description of migration semantic via explicitly describing the production reconfigurable migration.
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Computer Engineering. 2008, 34(16): 153-156. https://doi.org/10.3969/j.issn.1000-3428.2008.16.053The Boolean functions are correlation-immune if their outputs do not leak the information about their inputs. Based on the column-balanced matrix, this paper studies the problem of counting the correlation-immune functions, associates enumeration and statistic to count the 2k×6(0≤k≤16) order ordinal column-balanced matrixes, and puts forward a new enumeration algorithm of six-variables 1st-order correlation-immune functions. Compared with Sung’s algorithm, the complexity of the algorithm is decreased to (224), therefore the efficiency of counting the six-variables 1st-order correlation-immune functions is greatly improved.
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Computer Engineering. 2008, 34(16): 157-158. https://doi.org/10.3969/j.issn.1000-3428.2008.16.054Algebraic attack is an efficient cryptanalysis method. Grobner basis technique can be applied to solve systems of polynomial equations in several variables. This paper introduces a new efficient algebraic attack based on Grobner basis, describes Rijndael encryption by an extremely sparse overdefined multivariate quadratic system over GF(2), and converts degree reverse lexicographic order into lexicographic order with conversion algorithm FGLM. By reasonable designed order and solution set judgment, the complexity of Grobner basis attacks is efficiently reduced. Grobner basis attack can recover the full cipher key requiring only a minimal number of plaintext/ciphertext pairs.
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Computer Engineering. 2008, 34(16): 159-161. https://doi.org/10.3969/j.issn.1000-3428.2008.16.055To cope with the problem of heap memory leak, this paper presents a dynamic memory leak check technology based on red-black tree. With the method of dynamically catch the allocated situation of heap memory caused by the operator of new and delete during the execution of the program, decide whether the heap memory leak occurs. The system is implemented based on red-black tree, to manage the allocated heap memory. It is proved by theory induction and experiment that it has higher efficiency and is well platform-independent and scalable.
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Computer Engineering. 2008, 34(16): 162-164. https://doi.org/10.3969/j.issn.1000-3428.2008.16.056Side-channel attack is a new cryptanalysis, and the current cryptographic algorithms are vulnerable to higher-order side-channel attack. The leakage model and adversary model are introduced, a new countermeasure based on inserting random delay is proposed to secure AES against higher-order side-channel attack. By inserting a redundant instruction, it is expected to reduce the correlation between the leakage and the inside operations, and thus make the statistic analysis infeasible. Simulation verifies the efficiency of the proposed method.
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Computer Engineering. 2008, 34(16): 165-167. https://doi.org/10.3969/j.issn.1000-3428.2008.16.057A novel design of Elliptic Curve Cryptography(ECC) IP, using hierarchical method, new point operation scheme and enhanced Montgomery multiplier, is proposed based on ECC over GF(p). It can perform ECC point scalar multiple, point double and point addition/ subtraction operation and support RSA. The IP, under a frequency of 100 MHz, can fulfill 120 and 18 times of point multiple per one second respectively on 256 bit and 521 bit elliptic curve suggested by NIST. The design has passed ASIC synthesis and FPGA verification.
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Computer Engineering. 2008, 34(16): 168-170. https://doi.org/10.3969/j.issn.1000-3428.2008.16.058The harm which is done by executable malicious codes through controlling the processes becomes more and more severe to operating systems. So ensuring the security of process is the key to the operating system security. Based on theory and conception of secure operating system and trusted computing, an access control model named URPP is shown, which can defend operating system against the harm done by executable malicious code. URPP takes the process as a core element, measures the reliability and restricts the minimized privilege to the initializing processes. The URPP model applied to operating system security reinforces production successfully, and defends operating system against the executable malicious code effectively.
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Computer Engineering. 2008, 34(16): 171-172. https://doi.org/10.3969/j.issn.1000-3428.2008.16.059A secure and reliable (k, n) image secret sharing scheme is proposed. This scheme’s advantages are its large compression rate on the size of the image shares and it has no mass property in image reconstruction phase. Because the original secret image is divided into some block images in the new scheme, it has the ability of the real-time processing. This scheme is useful in the high requirement of the image security.
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Computer Engineering. 2008, 34(16): 173-176. https://doi.org/10.3969/j.issn.1000-3428.2008.16.060Because conspiracy cheat in most Reputation system is often plotted by two or three peers, a simple and convenient method to Anti-Conspiracy of Reputation(ACR) is presented. It identifies the Conspiracy Peers(CPs) by calculating the rating similarity and the average rating between peers, and then corrects the peer’s reputation. But it can’t classify the conspiracy group and High Trusted Group(HTG). In order to overcome this deficiency, this paper presents a new method compatible with HTG, where a Trust Matrix(TM) is adopted, both reputations inside and outside HTG are calculated respectively, and the reputation which the trust judgment adopts is decided by the relationship of the peers. Example analysis shows two methods are helpful to ACR.
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Computer Engineering. 2008, 34(16): 177-179. https://doi.org/10.3969/j.issn.1000-3428.2008.16.061On the basis of analyzing the features of electronic ecommerce systems, a novel electronic ecommerce systems model based on Communicating Sequential Processes(CSP) and dynamic game is proposed. Modeling channels in different qualities and participants of dishonest behaviors help to analyze cooperative and adversarial behaviors. Modeling process failure and channel failure help to analyze a protocol’s security properties in failed environment.
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Computer Engineering. 2008, 34(16): 180-182. https://doi.org/10.3969/j.issn.1000-3428.2008.16.062This paper analyzes advantages and drawbacks of some certificate revocation schemes in Ad Hoc network, presents a new distributed certificate revocation scheme, in which the certificate validity is controlled by the creditability of the nodes and uses one-way hash chain to authenticate revocation info, and self-healing communities to disseminate the accusation info via broadcast. The scheme does not rely on any centralized or external node, and it can effectively revoke the certificates of adversarial nodes and provide protection against certificates being wrongfully revoked. It analyzes quantitatively the reliability of the scheme.
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Computer Engineering. 2008, 34(16): 183-185. https://doi.org/10.3969/j.issn.1000-3428.2008.16.063This paper points the necessary conditions and main facts of information hiding security, and proposes the measurement guidelines of information hiding security. Based on the communications model of information hiding, it analyzes the security of information hiding both from the principle and threaten encountered, and gives out how all elements of the information hiding system influence its security, indicating that the securities of carrier message, hidden message and steganography key are necessary conditions of information hiding security, even the intensity of steganography key is its main fact, as imperceptibility, extractable resistance and robustness are its measurement guidelines in the view of resist attacks.
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Computer Engineering. 2008, 34(16): 186-187. https://doi.org/10.3969/j.issn.1000-3428.2008.16.064Physical isolation, in the way of safety isolation and information exchange system, is the prerequisite of building e-government. How to realize data exchange and sharing in heterogeneous system and database environment is a difficult issue. This paper proposes an XML-based distributed database synchronization strategy. It is based on the XML standard to describe the documents and data conversion rules, and uses the interface layer to the assembly as a data packet transmission unit to meet different levels of security network connecting to solve the data transmission problems in distributed databases.
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Computer Engineering. 2008, 34(16): 188-190. https://doi.org/10.3969/j.issn.1000-3428.2008.16.065Considering the premature convergence problem of Particle Swarm Optimization(PSO), a new Adaptive Particle Swarm Optimization with Mutation(APSOwM) is presented based on the variance ratio of population’s fitness. During the running time, the inertia weight and the mutation probability are determined by two factors: the variance ratio of population’s fitness and the average distance of current population. The ability of APSOwM to break away from the local optimum and to find the global optimum is greatly improved by the adaptive mutation. Experimental results show that the new algorithm is with great advantage of convergence property over PSO, and also avoids the premature convergence problem effectively.
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Study of Non-negative Matrix Factorization Initialization and Its Application to Text ClassificationComputer Engineering. 2008, 34(16): 191-193. https://doi.org/10.3969/j.issn.1000-3428.2008.16.066The initialization of Non-negative Matrix Factorization(NMF) has studied in this paper. There are three methods of initialization PCA, supervised PCA(SPCA) and Fuzzy C-Mean(FCM) are reported for text classification. Experimentsal results of multi-class text classification indicate that the three methods effectively solve the problem of results effected by initialized values, and improve the text classification results. The SPCA of the three methods is best.
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Computer Engineering. 2008, 34(16): 194-197. https://doi.org/10.3969/j.issn.1000-3428.2008.16.067A new adaptive-probability algorithm for global optimization, Living Migration Algorithm(LMA), is proposed by simulation of bio-subsistence and bio-migration in this paper. It simulates the mechanism that biology decides whether to migrate by comparing the standard of living with the minimal life-needs for searching better life. Unknown search space can be acquainted gradually by means of the standard of living, and biology can judge whether to migrate in terms of the minimal life-needs for seeking better living space. The mechanism and the model of LMA are given. And also given are convergence quality of LMA dealing with the global optimizations in terms of probability. Experimental results show that LMA has perfect convergence.
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Computer Engineering. 2008, 34(16): 198-200. https://doi.org/10.3969/j.issn.1000-3428.2008.16.068With regard to the problem that the efficiency of the classical multi-policies supporting mechanism, namely the Generalized Framework for Access Control(GFAC), markedly declines after enforcing several policy modules, a novel access control framework based on immunity is constructed with employing multiple principles and mechanisms of the artificial immune system, such as the immune recognition, the immune learning and the immune memory. Simulation result shows that IGFAC is able to improve the performance of the original GFAC, and it has some self-adaptive capabilities and diversity behaviors.
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Computer Engineering. 2008, 34(16): 201-203. https://doi.org/10.3969/j.issn.1000-3428.2008.16.069Local optimality and initialization dependence disadvantages of K-means are analyzed and a PSO-based K-means algorithm is proposed. The PSO is used to instruct the initialization of the cluster’s centers and it is made very easy to converge toward global optimality. The algorithm is applied to intrusion detection system, the results of tests elucidate that it clusters effectively, converges quickly and is realized easily.
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Computer Engineering. 2008, 34(16): 204-206. https://doi.org/10.3969/j.issn.1000-3428.2008.16.070Focused crawling research is key to search engine technology. In this paper, a focused crawling algorithm based on multi-Agent system is presented, which presents a core issue of a theme key words filtering method based on ontology to collect the URL related to the themes. Semantic network based on the ontology is to achieve filtering of similar meaning. It also introduces keyword identification of different weights by HTML page tags and anchor text, which are important for the website forecast use. And system model based on the blackboard communication mechanism is explained. The experimental results show that the system has an increasing promotion in both precision and extension for crawling website.
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Computer Engineering. 2008, 34(16): 207-209. https://doi.org/10.3969/j.issn.1000-3428.2008.16.071In this paper, a method for the tracking of single fingertip in scenes with complex background is proposed. This method uses a trinocular stereo vision system, named Digiclops, to capture images and to achieve the image blocks only containing the finger area. For the case that the finger perpendicularly points to the camera, the fingertip position can be rapidly obtained using a statistic-based method. While for other cases, a robust algorithm for fingertip location is presented. Experimental results show that the proposed method can accurately track the moving of the fingertip in a real-time way and can be used for the building of a Perceptual User Interface(PUI) system.
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Computer Engineering. 2008, 34(16): 210-211. https://doi.org/10.3969/j.issn.1000-3428.2008.16.072This paper aims at the problem of tracking user’s interest drift and optimizing user profile. It proposes a method of drifting user’s interests based on time window optimization. User profile tracks user’s interest drift by classification error-rate and when user’s interests are changed, user profile optimizes time window size automatically. Experiment shows that this method can describe the interest change of the user exactly and improve the personalization.
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Computer Engineering. 2008, 34(16): 212-214. https://doi.org/10.3969/j.issn.1000-3428.2008.16.073A novel intra-class sample selection method named kernel subclass convex hull sample selection algorithm is proposed and used for SVM. The algorithm is an iterative procedure based on kernel trick. At each step, only one sample furthest to the convex hull spanned by chosen samples is picked out in the feature space. Experiments show that a significant amount of training data can be removed without sacrificing the performance of SVM, while the memory requirements and the computation time of the classifiers are reduced significantly.
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Computer Engineering. 2008, 34(16): 215-217. https://doi.org/10.3969/j.issn.1000-3428.2008.16.074Genetic algorithm has been widely applied in path planning demonstrating good success. Traditionally, not-available paths and replacement proportion are deemed to be useless and always discarded directly by almost researchers in this field. However, this paper shows that this observation should be re-considered. By adding not-available path factor to fitness function after analyzing their performances and applying replacement proportion during the replacement process of father population by offspring population, very encouraging experimental results are achieved. All these observations suggest that more attention should be paid to traditionally abandoned not-available paths and replacement proportion for genetic algorithm in path planning application.
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Computer Engineering. 2008, 34(16): 218-220. https://doi.org/10.3969/j.issn.1000-3428.2008.16.075This paper proposes a new image thresholding segmentation method based on universal information law. Aiming at the disadvantage of entropy based thresholding method only making use of image gray probability information, and leading to be of no effect in segmentting some image, this paper presents universal information law in the information field in view of enlightenment from universal gravitation force law, and it is used to select optimal threshold of image segmentation. Experimental results show that the segmentation method of this paper is feasible, and segmentation quality of some image is much better than that of classical Kapur’s method based on Shannon’s entropy.
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Computer Engineering. 2008, 34(16): 221-223. https://doi.org/10.3969/j.issn.1000-3428.2008.16.076In the digital video signal processing, the technology of video moving object detection is very important. Mining meaning moving objects from a video image sequence by a certain method is its intention. In this paper, according to the analysis of the deficiency of the traditional threshold method, an improved 2D gray-level histogram combined with genetic algorithm is applied to enhance the speed and efficiency. A new method based on adaptive background subtraction and frame difference for the real-time detection of moving cars in complex scenes is proposed. Experimental results show that the new method has better environmental adaptive ability and can detect moving cars well.
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Computer Engineering. 2008, 34(16): 224-226. https://doi.org/10.3969/j.issn.1000-3428.2008.16.077Clustering analysis is broadly applied in data mining. This paper presents a new idea in clustering based on pair-wise similarities, and assumes no parametric statistical model. Similarities are transformed to a Markov random walk probability matrix. It is assumed the dataset is under a Markov random walk process. When the process is going into convergence, the t-step transform matrix indicates the distribution of the dataset. It uses iterative algorithm to cluster these data with the goal of decreasing KL-divergence. This method has a solid foundation of probability theory, which can avoid some insufficiency of the traditional algorithms. The experiment shows the algorithm can achieve better results than K-means and mixture models.
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Computer Engineering. 2008, 34(16): 227-229. https://doi.org/10.3969/j.issn.1000-3428.2008.16.078Camouflage assessment is an essential part in camouflage design. Using computer analysis instead of subjective evaluation can make the assessment more stable and effective. This paper proposes a new method using texture characteristics from multi-wavelet decomposition. Texture similarity is used to assess the camouflage. Experimental data demonstrates the effectiveness of the approach.
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Computer Engineering. 2008, 34(16): 230-231. https://doi.org/10.3969/j.issn.1000-3428.2008.16.079This paper proposes one new multifocus image fusion algorithm based on Neighborhood Limited Empirical Mode Decomposition (NLEMD). The images are decomposed by NLEMD, and this algorithm makes full use of adaptive features of NLEMD and the powerful achieving capability of high frequency data to fuse images. In different Intrinsic Mode Functions(IMF) the pixel which has the local max energy is selected as the fusion pixel, and the image is reconstructed using IMFs and remnants. Experiments prove that the new algorithm has more powerful achieving capability of high frequency data and better effect than fusion algorithm based on wavelet analysis.
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Computer Engineering. 2008, 34(16): 232-234. https://doi.org/10.3969/j.issn.1000-3428.2008.16.080This paper develops a new general Viterbi MHT algorithm for multitarget tracking. A measurement “gating” is used in the algorithm, and the target associates the measurement that is in the “gating”. The method can decrease the number of hypothesis, reduce the computational burden of the algorithm, and benefit for pruning/merging. MAP path costs are computed by using Kalman filters and priori probabilities. The algorithm is sequential, and can deal with missed detections, false alarms and the number of track target. It can provide a list of best track sets.
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Computer Engineering. 2008, 34(16): 235-237. https://doi.org/10.3969/j.issn.1000-3428.2008.16.081This paper presents a method of lossless data hiding for image. This method chooses the digital image as the original and to-be-embedded data according to the basic principles of lossless data hiding. It modifies the histogram to avoid the overflow of the borderline data, and uses the integer wavelet lifting and the histogram bit-shift to realize the data hiding. The result shows this algorithm has large hiding amounts, little distortion and easy reconstruction. It has been applied in many fields such as medical treatment, law and military affairs.
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Computer Engineering. 2008, 34(16): 238-240. https://doi.org/10.3969/j.issn.1000-3428.2008.16.082Based on requirement of network conferences for networked collaborative product design processes in Web environment, transmit and control technology of streaming media and Java Media Framework(JMF) technology are analyzed, Real-time Transport Protocol(RTP) and Real-time Transport Control Protocol(RTCP) and mechanism of JMF RTP programming are discussed. System infrastructure of similarity Browser/Server(B/S) structure and streaming media synchronization mechanism based on timestamp are put forward, video conference system of similarity B/S structure is developed based on JMF, system framework design and browser design of client-end are realized, and integration with Product Data Management(PDM) system is implemented.
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Computer Engineering. 2008, 34(16): 241-243. https://doi.org/10.3969/j.issn.1000-3428.2008.16.083An improved algorithm for down-scaling video transcoding is proposed based on diversity & importance transcoding architecture. By using the variance measure and an adaptive classification method, it can choose the appropriate re-encoding mode of each block in various video sequences. The algorithm produces about 1dB PSNR higher than the traditional mv-composition algorithm. While preserving high transcoding quality, it produces only 40%~95% bits than AMVR-DIM method.
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Computer Engineering. 2008, 34(16): 244-246. https://doi.org/10.3969/j.issn.1000-3428.2008.16.084The latest video coding standard proposes a simple yet efficient hybrid FME scheme based on the existing UMHexagonS scheme. This paper introduces this new fast search algorithm. Some improved schemes are proposed based on the study and analysis of the advantages of simplified UMHexagonS algorithm, such as introduces more early terminate criterions, further division to the motion type, adoptes directional search patterns for different blocktype adaptively, etc. Experimental results show that the improved strategies can reduce about 8%~10% of motion estimation time, while the R-D performance and bit rate are almost the same as simplified UMHexagonS algorithm.
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Computer Engineering. 2008, 34(16): 247-248. https://doi.org/10.3969/j.issn.1000-3428.2008.16.085In view of tracking difficulty of multiple view angles about multi-actors from monocular video, a tracking method based on Dynamic Bayesian Network(DBN) is proposed which operates on monocular gray-scale video imagery. It puts forward an united model according to the combination of the actors’ figure features and the spatial motorial features in order to track multi-actors of multiple view angles in the monocular video. Experiment shows that this method is effective and robust.
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Computer Engineering. 2008, 34(16): 249-251. https://doi.org/10.3969/j.issn.1000-3428.2008.16.086In allusion to the rotors imbalance problem of revolving machines in the industry, this paper puts forward a solution based on ARM embedded technology and develops a test system of self-adaptive dynamic balance for rotors. The designing thoughts and process of hardware and software are expatiated. The system realizes a method that rotors can gain the unbalanced amounts only once without trial masses, based on two-side influencing coefficient method and self-learning mechanism. Considering a critical factor-rotor speed, the system also realizes a self-adaptive process of dynamic balance test.
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Computer Engineering. 2008, 34(16): 252-254. https://doi.org/10.3969/j.issn.1000-3428.2008.16.087Considering the current management in the pattern of road transportation enterprise, this paper constructs the business mode of road transportation which related to the logistics resource, storage, transportation and distribution, designs a logical information data center and module of platform structure which are based on the result of discovery, and prospects the experiment efficiency in the information platform of logistics. In virtue of the ASP.NET, it deploys the platform by tropical structure, summarizes an optimize software and exploitation idea, and that is the reasonable and consultable project comes for, the realization of final software and hardware which is necessarily for the platform running.
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Computer Engineering. 2008, 34(16): 256-258. https://doi.org/10.3969/j.issn.1000-3428.2008.16.088The workflow technology is quite fit to develop management information system of power distribution enterprise, with production management having strong characteristics of business process. Based on workflow technology, this paper analyzes the requirement of MIS applied to the power distribution enterprise. How to abstract and describe business process, to deal with data flow, to design user action and action monitoring within system design are given. The management information system is realized by using BEA Weblogic integration of a workflow management system. Practices show the system is effective.
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Computer Engineering. 2008, 34(16): 259-261. https://doi.org/10.3969/j.issn.1000-3428.2008.16.089To use only one integrated software to supervise and manage multi fire alarm devices produced by different factories located in the same precinct or near by, this paper describes the structure of integrated supervisor and management software for fire alarm system, including the main functions of communication model, proposes a new kind of linkage control method which is feasible to be used to synchronize the operation between multi different fire alarm devices.
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Computer Engineering. 2008, 34(16): 262-264. https://doi.org/10.3969/j.issn.1000-3428.2008.16.090This paper studies the power management system design for the System-on-Chip(SoC) processor technology. The characteristic of the processor’s Power Management Unit(PMU) is analyzed. According to its application demands, it discusses the design problems of Power Management IC(PMIC), which includes: the interior architecture of the power IC and its selection principle, the improvement of the digital PMIC in contrast with the traditional power IC, the application of a new power management bus called PMBus and a highly integrated PMIC. It analyzes the design of Dynamic Power Management(DPM), which is a module in the embedded operating system.
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Computer Engineering. 2008, 34(16): 265-267. https://doi.org/10.3969/j.issn.1000-3428.2008.16.091This paper introduces the document structure of the Substation Configuration description Language (SCL) in the IEC61850 standard. It expatiates the configuration flow of the system as well as the exchange process of the data document, and brings forward to use the Native XML Database(NXD) technology in maintaining the XML documents. It takes the XML text file as the store unit. The system creates two index file and uses the traditional B+ tree data structure to set up the index. It uses the XPath expression to query in the XML file.
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Computer Engineering. 2008, 34(16): 268-270. https://doi.org/10.3969/j.issn.1000-3428.2008.16.092This paper presents a method to extract the formal concept from the product information, and constructs the formal context. By using concept lattices, the idea to describe the product information is proposed. Two optimum strategies for browsing concept lattices are given. One is key-lattices and the other is cluster concept. Compared with the conventional imformation browse, test results show that it has more flexibility and can display the relationship and difference between products clearly.
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Computer Engineering. 2008, 34(16): 271-273. https://doi.org/10.3969/j.issn.1000-3428.2008.16.093Aiming at the different technology standards of 3G mobile communications, this paper presents a uniform technology platform of 3G mobile communications based on the VxWorks environment. The architecture of this system and the function of its subsystems are introduced. The inner principles and essential operation process are analyzed. This platform provides strong support for further research. Practices show this platform is effective.
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Computer Engineering. 2008, 34(16): 274-276. https://doi.org/10.3969/j.issn.1000-3428.2008.16.094The distributed spatial data registration container is one of the most important spatial data discovery mechanisms in the platform of National Geological Spatial Information Grid(NGSIG). This paper introduces the design idea about the registration container structure, and explains some important characteristics of the registration container. The two important parts of the container, the node container and the portal container, are described in the paper. The data registration container is implemented in the system of NGSIG platform. The application results in the process of spatial data integration show that it works well.
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Computer Engineering. 2008, 34(16): 277-279. https://doi.org/10.3969/j.issn.1000-3428.2008.16.095This paper presents a RFID tag identification algorithm based on Tag’s ID feedback and model-string recognition, and solves the zero-response problem in the RFID arbitration. With 5 000 tags swatch, experimental results show that this algorithm takes 48.74% and 33.89% times of Tag response, compared with the Memoryless and Tree Split. The ID broadcasting times is less than 76.35% of that two classic algorithms. It is more efficient and shortens the time needed during the arbitration process.
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Computer Engineering. 2008, 34(16): 280-282. https://doi.org/10.3969/j.issn.1000-3428.2008.16.096It is necessary to test and analyze the capability of various distributed objects techniques. To solve the problem to choose preferred plan from a number of distributed objects techniques, some familiar J2EE distributed objects techniques are tested by the high-precision arithmetic of circumference ratio(Bailey-Borwein-Plouffe arithmetic). A lot of data obtained by these tests reflect the capability of computing and starting on these techniques. The significance of these data for application is discussed to design distributed computing system on J2EE.
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Computer Engineering. 2008, 34(16): 283-285. https://doi.org/10.3969/j.issn.1000-3428.2008.16.097This paper analyzes the usual algorithms with less anti-jamming ability which are sensitive to the effect of noise in the application of ellipse fitting, and proposes a more robust ellipse fitting algorithm. It utilizes the heteroscedastic regression technique to create the Errors-In-Variables (EIV) model. According to the observation of data vector, the optimal algorithm is found to obtain the optimal estimations of EIV model parameters and the truth-value of the observed data vector. Experimental results show that the algorithm is more accurate and can converge steadily and rapidly, when original data is far from exact value.
2024
Volume 50 No 3
Volume 50 No 3
(Started in 1975, Monthly)
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428