05 July 2009, Volume 35 Issue 13
-
Select all|
-
Computer Engineering. 2009, 35(13): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2009.13.001Aiming at the problems of integration of real-time services in Internet, an heterogeneous real-time services integrated platform based on Session Initiation Protocol(SIP) is proposed, in which, real-time services are assigned SIP URI address and encapsulated into atomic services with uniform interface. Atomic services are invocated by service-register and application-layer-routing mechanisms. Considering scalability of the platform, real-time information is transferred by P2P method. By implementing the prototype system, the public traffic guide system, the feasibility of this platform is proved.
-
Computer Engineering. 2009, 35(13): 4-7,10. https://doi.org/10.3969/j.issn.1000-3428.2009.13.002In order to solve multi-constraint 0-1 knapsack problem, a new profit-density is designed, on basis of which, a Hybrid Genetic Algorithm(HGA) based on greedy algorithm is proposed, which uses the binary code to amend the feasible solution, and applies roulette wheel selection method to rectify knapsack resources with insufficient use, and repairs the infeasible solution. The algorithm is compared with other traditional ones. Experimental results show this HGA can promote the speed and accuracy of solving relevant problems efficiently, and is superior.
-
Computer Engineering. 2009, 35(13): 8-10. https://doi.org/10.3969/j.issn.1000-3428.2009.13.003A pyramid method for automatic summarization evaluation based on Dependent Content Units(DCU) is proposed. By identifying DCU, the pyramid model is set up, and the corresponding process of automatic evaluation is given. The method avoids the unstability in manual processing and implements the full automation in the whole process of evaluation. Simulation experimental results show the relevant coefficients called Person and Sperman of this method are higher than traditional ROUGE-1 algorithm.
-
Computer Engineering. 2009, 35(13): 11-13,1. https://doi.org/10.3969/j.issn.1000-3428.2009.13.004Aiming at the resource-located problems and free-riding phenomenon during sharing P2P information in large scale network, this paper proposes a semantic community establishing method based on consideration of semantic similarity degree, trust degree and active strength, which improves the structural and resource-located veracity of P2P resource organization. A dynamic evolution mechanism of communities based on trust evaluation is built to reduce and eliminate the free-rider peers.
-
Computer Engineering. 2009, 35(13): 14-16. https://doi.org/10.3969/j.issn.1000-3428.2009.13.005The characteristics of business process are analyzed, and a collaborative modeling method based on role privilege controlling is provided. Top-down collaborative modeling procedure is built via process model decomposition. A controlling mechanism based on role privilege is also applied to achieve logical separation between modeling user and access privilege. Update lock, freeze lock and four locking principles are introduced into the collaborative modeling mechanism. Simulation experimental results show this method is effective and feasible.
-
Computer Engineering. 2009, 35(13): 17-19,6. https://doi.org/10.3969/j.issn.1000-3428.2009.13.006This paper presents a monitor framework for software properties based on the techniques of Aspect Oriented Programming(AOP). This framework generates monitoring aspects from Object Constraint Language(OCL) constraints. By weaving monitor aspects with software monitored, the software can find any runtime violation of constraints. The information of violation of constraints can be analyzed further by using UML Specification Environment(USE). After the analysis, the information of violation will be shown on the model.
-
Computer Engineering. 2009, 35(13): 20-22,6. https://doi.org/10.3969/j.issn.1000-3428.2009.13.007A single software upgrade method can hardly meet the upgrade requirements of all software. A variety of software upgrade methods’ advantages, disadvantages and applicable situations are analyzed. A remote online VxWorks software upgrade system is designed, principle and implementing method of dynamic software update are discussed. Some design approaches to improve upgrade reliability are introduced. The realization of the system is described. The system uses in combination three software upgrade methods, it can basically meet the upgrade requirements of various software.
-
Computer Engineering. 2009, 35(13): 23-25. https://doi.org/10.3969/j.issn.1000-3428.2009.13.008Aiming at the maintenance and evolvement of ontology model, this paper combines algebraic lattice with concept lattice, defines concept algebra, and proposes 3-layers architecture of ontology evolution, which consists of atomic concept level, atomic concept relations level, and application level. The corresponding relations between concept algebra and Ontology Web Language(OWL) are analyzed. In the application level, application-oriented concept can be builded according to the applied requirement, and existing ontology model can be maintained. An example is designed to validate the method.
-
Computer Engineering. 2009, 35(13): 26-27,5. https://doi.org/10.3969/j.issn.1000-3428.2009.13.009This paper presents a method based on Non-negative Matrix Factorization(NMF) for Chinese document topic classification. According to NMF, the term-document matrix is decomposed to reveal the relationship between terms. This method solves the problem of synonym and polysemy effectively. Compared with Latent Semantic Indexing(LSI) based on Singular Value Decomposition(SVD), experimental results show that this method has faster computing speed and less memory occupancy. It can improve classification precision when the number of latent semantic index is reduced pronouncedly.
-
Computer Engineering. 2009, 35(13): 28-30. https://doi.org/10.3969/j.issn.1000-3428.2009.13.010In the same domain, different Web databases have overlap with each other. In order to estimate the overlapping rate in Web database, this paper proposes an attribute high-frequency words based approach for estimating the overlapping rate of Deep Web database. Starting with the Chinese frequency words, the attribute frequency words can be induced iterative, and using its query results calculate the conditional probability of overlapping part, then estimate the overlapping rate. Experiments prove its bias and volatility are less than 5.
-
Computer Engineering. 2009, 35(13): 31-33. https://doi.org/10.3969/j.issn.1000-3428.2009.13.011At present most personalization service systems use keywords or keyword vector space models to express users’ personal preferences, but it severely restricts the sharing and reusing of user model between different personalized systems. Focusing on the problem, this paper proposes a user model called DOBUM(Domain Ontology-Based User Model) and presents its structure. To realize the quantification of users’ personal preference, the definition of personalized interest level is introduced. The application process of DOBUM in the group user modeling is presented. The model is proved to reflect users’ interests exactly and have strong renewal ability and extendibility by analyzing the contrastive result on data.
-
Computer Engineering. 2009, 35(13): 34-36. https://doi.org/10.3969/j.issn.1000-3428.2009.13.012A wide variety of applications require access to multiple heterogeneous, distributed data sources on grid. The quality of data access is still low, because existing query optimization techniques do not consider the dynamic properties of data resource in grid environments. This paper uses segmented pipe tree based on pipelined parallelism to optimize the multi-join queries, and takes into account the user’s QoS requests in the query optimization. Experimental results confirm that the solution is effective for providing QoS-supported data service for different users.
-
Computer Engineering. 2009, 35(13): 37-39. https://doi.org/10.3969/j.issn.1000-3428.2009.13.013Aiming at the features of data streams, this paper presents an incremental maintaining algorithm based on frequent closed itemsets mining according to Moment algorithm. It incrementally updates the transactions in the data stream via a sliding window, and uses an effective bit-sequence representation of items to reduce time and memory of the sliding window. A compressed pattern tree is used in frequent closed itemsets test to guarantee veracity. Experimental results show that this algorithm is effective.
-
Computer Engineering. 2009, 35(13): 40-42,4. https://doi.org/10.3969/j.issn.1000-3428.2009.13.014When extracting key concepts and relations in traditionally ontology creating, it adds the cost of creating an ontology and restricts the development and population of semantic Web if specialists from several fields take part in. To solve the problem, this paper analyzes the differences between UML class diagram and OWL, proposes the method of mapping the fields knowledge extracted from UML model such as concepts, attributes, relations and restricts of the ontology to OWL ontology, and illustrates the OWL ontology mapping based on UML class diagram to realize convenience and efficiency of ontology creating.
-
Computer Engineering. 2009, 35(13): 43-45. https://doi.org/10.3969/j.issn.1000-3428.2009.13.015It is necessary to use an appropriate algorithm in load balancing technology to choose a member, and determine which copy object to deal with the dispatched requests. Aiming at the problem that the traditional round robin algorithm can only implement load balancing in some occasions, this paper presents a round robin algorithm based on trigger mechanism which integrates the advantages of traditional round robin algorithm and weight-based round robin algorithm. Experimental results show that this algorithm can sense the changing of the background resources.
-
Computer Engineering. 2009, 35(13): 46-48,7. https://doi.org/10.3969/j.issn.1000-3428.2009.13.016This paper focuses on how to minimize the access time and tuning time of the XML data broadcast in mobile computing environments, and proposes an XML data broadcast scheduling algorithm named XAISA(XML broadcast Scheduling Algorithm based on Adaptive Index) based on adaptive index. Its performance can be optimized by adjusting the degree of data blocks dynamically according to system workload, and it can significantly shorten the average tuning time at the cost of slight increment in average access time and the time of receiving XML broadcasting data, which is indicated by performance analysis and experimental results.
-
Computer Engineering. 2009, 35(13): 49-51. https://doi.org/10.3969/j.issn.1000-3428.2009.13.017The traditional search methods suffer from the problems of high time complexity and easily getting wrong candidate mapping sets. This paper proposes an improved method of search candidate mapping sets. This method obtains the initial candidate mapping sets through comparing the similarity between the different concepts, and extends them by making use of correlation to get the final candidate mapping sets. Compared with traditional methods, experimental results prove that this method is valid.
-
Computer Engineering. 2009, 35(13): 52-54. https://doi.org/10.3969/j.issn.1000-3428.2009.13.018Active XML(AXML) is an XML document where some of the data is given explicitly while other parts are given intentionally, by means of embedded calls to Web services. This paper gives an AXML document, a specification describing intensional data and a target exchang schema. It formalizes the problem based on formal languages theory and provides an algorithm to solve it. It also presents an implementation of test environment of AXML exchange. Experimental result demonstrates that the algorithm based on tree automata can lead to the increase of efficiency on exchang AXML documents.
-
Computer Engineering. 2009, 35(13): 55-57. https://doi.org/10.3969/j.issn.1000-3428.2009.13.019Aiming at the lack of most existing architecture description language to describe system behaviors may cause generation test paths difficultly, this paper proposes a software architecture test technology based on π calculus. The technology makes π calculus combining with Petri net, makes the software architecture model and proposes test paths generation algorithm. Experiment shows that the proposed algorithm can generate test paths according to test criteria to realize architecture model dynamic and test technology effective.
-
Computer Engineering. 2009, 35(13): 58-60. https://doi.org/10.3969/j.issn.1000-3428.2009.13.020Aiming at the time-consuming problem of multiple reformulations when bypassing left peers in peer data management system, a peer schema mapping composition method is proposed based on XSLT template unfolding. By matching and unfolding template contents consecutively, the method processes two mappings expressed in an XSLT subset with the style of matching templates, and forms a composed mapping equivalent to multiple mappings. When neighboring peers on mapping path depart together, agent peer no longer reformulates multiple times, but uses composed peer to bypass directly. Simulation results show that the composition method can produce equivalent mappings correctly. By passing time shortens significantly and network topology becomes robust.
-
Computer Engineering. 2009, 35(13): 61-62,6. https://doi.org/10.3969/j.issn.1000-3428.2009.13.021Aiming at the error when stream interface drivers for Windows CE access the memory bank of applications by the embedded pointer, this paper analyzes the error causes and elaborates some essential concepts of Windows CE memory access, including pointer parameter, embedded pointer, synchronous access, access checking and memory marshalling. This paper proposes a solution that the embedded pointer should be marshaled when asynchronous access. Result proves that the solution can effectively solve the problem of asynchronous memory access errors.
-
Computer Engineering. 2009, 35(13): 63-65. https://doi.org/10.3969/j.issn.1000-3428.2009.13.022This paper introduces membership function into fuzzy queries, and presents membership degree which can reflect its fuzziness in the query result. Users can adapt the scale of fuzzy range by setting parameter in membership function or altering values in the histogram, and set different confidence to query different reliable data. Experimental result shows that, the higher the confidence is, the more precise the result is, but the less the result is. Inversely, the lower the confidence is, the less precise the result is, but users can get more query results.
-
Computer Engineering. 2009, 35(13): 66-68. https://doi.org/10.3969/j.issn.1000-3428.2009.13.023This paper analyzes two existing problems in ontology matching algorithm based on semantic Web. It presents a new algorithm, which uses ontology matching based on virtual document to retrieval synset in the WordNet, and changes a single concept used by ontology searching into a concept set, so it can enlarge searching scope and obtain more background ontologies. It uses dynamic ontology matching based on semantic environment to exclude wrong background ontologies, so it can get more precision in ontologies collecting. Experimental result shows precision and recall of matching improved effectively by using the improved algorithm.
-
Computer Engineering. 2009, 35(13): 69-71. https://doi.org/10.3969/j.issn.1000-3428.2009.13.024This paper discusses the incremental update for negative association rules. The incremental update for negative association rules and the positive association rules is different. That is the negative association rules not only exist in the frequent itemsets, but more exist in the infrequent itemsets. This paper proposes an incremental update for the negative association rules algorithm, NIUA. The algorithm uses the improved Apriori algorithm and the set nature to mine the frequent and infrequent itemsets and mines the negative association rules by algorithms. Experimental result show that the algorithm is retrievable.
-
Computer Engineering. 2009, 35(13): 72-74. https://doi.org/10.3969/j.issn.1000-3428.2009.13.025The technology of register rotation provides a set of registers for every circle iteration to reduce the need of circle operation. This paper proposes a solution of processing rotating register in IA-64 binary translation, which adopts the method of simulating rotating registers directly in the back-end of binary translator. Experimental result show that the validity of the proposed technique is the processing software pipelining in the binary translation.
-
Computer Engineering. 2009, 35(13): 75-77. https://doi.org/10.3969/j.issn.1000-3428.2009.13.026With the expansion of network scale and the complexity of network construction, it is a big challenge to previous network monitoring technologies. After the analysis of network monitoring technology and Intelligent Agent(IA) technology, this paper proposes a method based on IA to complete dynamic network monitoring, including two modes: automatic and manual, developed by a cross-platform language, Python. Experimental result shows that the method can be used in various network environments and topologies, and it is reliable to collect node’s information in network. It can improve the reliability of network.
-
Computer Engineering. 2009, 35(13): 78-80. https://doi.org/10.3969/j.issn.1000-3428.2009.13.027To satisfy with the communication requirements of many-to-many multicast applications, this paper discusses the problem of multi-source application level multicast. A Multi-source Application Level Multicast Model(MALMM) is presented which consider the optimization of overlay node’s load and constraint of data delivery delay. It devises a Multi-source Application Level Multicast Routing Algorithm(MALMRA) for solving MALMM. In addition, based on linear programming relaxation theory, a method to compute the theoretical lower bound of MALMM’s solution is introduced. Experimental results show that solutions obtained through MALMRA are close to the theoretical lower bounds as well as better than solutions obtained through ABDD and ABDDR which are algorithms constructing data delivery trees in isolation, it is an efficient MALMRA.
-
Computer Engineering. 2009, 35(13): 81-83,8. https://doi.org/10.3969/j.issn.1000-3428.2009.13.028The components and functions of autonomic communication systems are described, and it can be viewed as a special kind of feedback control systems with the elements of collecting, decision, analyzer and actuator. This paper focuses on the decision-element. The decision-element uses optimal policies based on QoS with Markov Decision Process(MDP), which seekes to satisfy a set of system QoS. Simulation results show that communication system adaptation can be guided by decision rules based on QoS found by the methods of MDP, when there are multiple controlled features and multiple system measures used to drive the decisions.
-
Computer Engineering. 2009, 35(13): 84-87. https://doi.org/10.3969/j.issn.1000-3428.2009.13.029In the Mobile Ad hoc Network(MANET), the efficiency multicast route is one of hot-study for the network multicast routers. This paper proposes a base scale agent method, which is used in the Multicast Ad hoc On-Demand Vetor(MAODV) multicast router protocol base on deeply-analyzed, expanding the protocol content. It uses the region scale agent to manage and multicast the data-packages by combining unicast with broadcast, expanding the protocol. Simulation results demonstrate SAMAODV not only can decrease network overhead and average end-to-end delay, but olso can decrease the number tree’s reconstruct and enhance the pakects delivery ratio.
-
Computer Engineering. 2009, 35(13): 88-89,1. https://doi.org/10.3969/j.issn.1000-3428.2009.13.030According to the different characters of the sequence for different forecasting models, the applied conditions of various forecast are analyzed, two kinds of exponential smoothing models and gray model GM(1,1) are illuminated. This paper proposes a Mixed Forecast Model(MFM) which can adapt to the network performance data. By the practical applications, it proves that the forecast effect of MFM is good, and MFM can realize the function of network forecast well in period of time.
-
Computer Engineering. 2009, 35(13): 90-92. https://doi.org/10.3969/j.issn.1000-3428.2009.13.031Aiming at different actual network environments, this paper discusses a new routing approach based on ant algorithm to obtain the optimum path between two nodes in network. Considering consumption and delay of link between route nodes, the speed of convergence is raised by increasing formulas’ sensibility to impact factors. Simulation results shows that, especially having considered two factors of cost and delay, the proposed approach can be used to search the routing efficiently by the available nodes and paths provided with the reconstructed network topology even if the network changed.
-
Computer Engineering. 2009, 35(13): 93-95,9. https://doi.org/10.3969/j.issn.1000-3428.2009.13.032In Application Layer Multicast(ALM), if none-leaf nodes leave or fail, all of this node’s download nodes will be greatly affected. On this issue, this paper proposes a new proactive approach to restore overlay multicast, and each non-leaf node precalculates a parent-to-be for each of its children. So that the non-leaf node fails or leaves, the children nodes can accept data quickly from parent-to-be. Simulation experiment demonstrates the proactive approach can recover from node departures about 3 times faster than reactive approach, and average delivery delay is smaller than other proactive approaches with low overheads.
-
Computer Engineering. 2009, 35(13): 96-98. https://doi.org/10.3969/j.issn.1000-3428.2009.13.033Access control of Cognitive Radio Network(CRN) where Cognitive Radio Users(CRU) share spectrum access opportunities with licensed users is studied. The cooperative access control strategies are illustrated. The transparent access control strategies are focused on, which are based on respectively Markov model and prediction. Transparent strategies on the basis of power control are analyzed for the various service requirements and interference. The key problems about the further research of the access control in CRN are proposed.
-
Computer Engineering. 2009, 35(13): 99-101,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.034A new algorithm is put forward in Dynamic Equilibrium of Multipath Traffic(DEMT) for the purpose of solving the shortcomings of the load distributing multipath algorithm. According to topological structure of putting vector weight, a mathematical model of distributing multipath is set up on network traffic. In this algorithm, the probability coefficient is constructed and it is regarded as the standards of select path, and the load rate variable and the least hop variable on QoS attribute is injected to deduce a optimizing algorithm of more reasonable equilibrium of the network resource. The simulation results show that the new method can avoid network congestion. Network traffic rate is controlled less than 70% and total delay time is reduced to 56% correspondingly.
-
Computer Engineering. 2009, 35(13): 102-104. https://doi.org/10.3969/j.issn.1000-3428.2009.13.035Router topology discovery is an important basis for the research of network structure and behaviors. IP alias resolution is a very difficult problem to be covered. This paper summarizes the existent approaches, and proposes a new solution for IP alias of routers, neighbors-subnet alias resolution. It is more believable and effective than the former methods, it cam resolve the IP alias problem of router preferably.
-
Computer Engineering. 2009, 35(13): 105-107,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.036A new distributed algorithm of data compression of hierarchical cluster model in sensor network is proposed. The whole sensor network is mapped into a hierarchical cluster model, and different wavelet transform models are used to do data compression in inner and super clusters respectively, according to the relative regularity of sensor nodes deployed in the inner clusters, and the relative irregularity of sensor nodes deployed in super cluster. Theoretical analysis and simulation results show that, the new method has good performance of approximation, can compress data and reduce the amount of data efficiently, and prolong the lifetime of the whole sensor network to a greater degree.
-
Computer Engineering. 2009, 35(13): 108-110. https://doi.org/10.3969/j.issn.1000-3428.2009.13.037In this paper, a wireless sensor network node transmission power is variable, whose radius of maximum emission energy is k times of the smallest radius r, namely the kr wireless sensor network. The best suitable energy radius of ir is studied comprehensive. Through rigorous mathematical analysis, the energy consumption formula is given, and the compute method of optimal energy emission level k is gained. The optimization transmit power can greatly improve network life compared with transmit power, which plays the important instructing role for wireless sensor network.
-
Computer Engineering. 2009, 35(13): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2009.13.038This paper proposes a kind of MAC protocol to improve the QoS of Wireless LAN(WLAN), describes the scheme of the protocol, and gives the comparison of the average delay and normalized throughput when transmitting real-time voice data between this protocol and 802.11e Enhanced Distributed Coordination Function(EDCF) by simulation. The simulation result shows that this protocol performs much better than EDCF when transmitting real-time data irrespective of load magnitude. So this protocol utilizes the channel more effectively.
-
Computer Engineering. 2009, 35(13): 114-116. https://doi.org/10.3969/j.issn.1000-3428.2009.13.039Because of the special environment of the mobile Ad Hoc, the management of it becomes very difficult. Aiming at this, by using the new zone generating algorithm, this paper proposes IZRP based on ZRP, which reduces the zones’ number and lessens the nodes’ overlap attach. The hierarchical network management based on IZRP shortens the time of routing transmit and enhances the management efficiency of the whole Ad Hoc network.
-
Computer Engineering. 2009, 35(13): 117-119. https://doi.org/10.3969/j.issn.1000-3428.2009.13.040By investigating characteristics of Internet traffic, this paper discoveres that moderate flows are few but have large proportion of the total bytes. It proposes a novel load balance algorithm named HAMF, which only adjusts the moderate flows when unbalanced. Validated by simulation, the scheme dispatches the bytes of load in a balanced way, disrupts flows at low rate, discards packets at very low rate, and satisfies the demand of network security. Compared with SHI scheme, the algorithm has better performances, but it is a little more complex.
-
Computer Engineering. 2009, 35(13): 120-121,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.041Aiming at the problem of adaptive chaos secure communication based on parameter modulation, information signals are used to modulate some parameter of a chaotic system in the master system, an adaptive salve system is designed by structuring adaptive parameter identification and single adaptive controller, it realizes chaos synchronization and parameter estimation effectively. The proper nonlinear filter is designed in the receiving terminal to make the information signals recover effectively, realizing the secure communication. The simulation results show that chaos synchronization is effective, and the recovered signals are close to the information signals, it possesses strong confidentiality. The controller is simple and it is easy to implement in engineering.
-
Computer Engineering. 2009, 35(13): 122-124. https://doi.org/10.3969/j.issn.1000-3428.2009.13.042A low-rate TCP-targeted Distributed Denial of Service(DDoS) is a network attack method which generates high rate and short burst length attack packets. It can easily pass through multi-level router filer or IDS, and make use of the innate weakness of TCP congestion control mechanism. The RTO of TCP congestion control mechanism is a certain value. A low-rate TCP-targeted DDoS attacker is synchronized with the RTO, so low-rate TCP-targeted DDoS can make the network’s throughput down just as the original DDoS and be very hard to be found out. Now there is no good method to deal with it. This paper shows how the randomized RTO can reduce the harm of low-rate TCP-targeted DDoS effectively through a series of experiments.
-
Computer Engineering. 2009, 35(13): 125-127. https://doi.org/10.3969/j.issn.1000-3428.2009.13.043In order to extend and diversify the carrier of protocol steganography, the possibility of concealing messages in IP option is studied. After analyzing the standard of network protocol, four new covert channels can be established in IP header through rewriting of option’s pointer field. The principles of covert channels are discussed and channels which can avoid router to overwrite are implemented at Internet circumstance by simulation. The countermeasure to steganalysis which should be taken is analyzed with newest development of network covert channel’s detection.
-
Computer Engineering. 2009, 35(13): 128-130,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.044According to the storage format and features of icon and bitmap resource, a new information hiding scheme based on PE resource is proposed. The scheme utilizes the imperceptibility of Portable Executable(PE) file to embed secret information into PE resources datum by applying information hiding algorithms. As a result, it enhances the information imperceptibility and capacity. In addition, a new palette redundant color allocating algorithm is proposed, which can improve the embedding capacity of information hiding algorithms based on palette color redundancy.
-
Computer Engineering. 2009, 35(13): 131-133. https://doi.org/10.3969/j.issn.1000-3428.2009.13.045Because the previous estimation methods lack of accuracy and real-time performance in solving the Hurst index, EBP is introduced to the analysis of network traffic self-similarity. The contrast experiments show that EBP is more accurate and has higher real-time performance than other methods in the Hurst index estimation. Taking these advantages of EBP, it is applied to online, real-time analysis of the macro network and the anomaly behavior detection. The analysis on macro network behavior data of Lincoln laboratory shows that the Hurst distribution curves between normal and abnormal behavior have obvious differences. Compared with the traditional method of matching, anomaly behavior detection method based on EBP is more efficient.
-
Computer Engineering. 2009, 35(13): 134-136. https://doi.org/10.3969/j.issn.1000-3428.2009.13.046This paper studies the limitation and shortage of eMule protocol’s security design. Based on the study, the eMule software can bring risk to users in three aspects such as privacy leaking, credit cheating and malicious code attack. The suggestions for improvement are proposed accordingly. A new attack method which is based on two leaks of the Ed2k link format is established. It designs the attack flow, and an attack simulation experiment is processed, which shows that the success ratio of this attack method is 100%.
-
Computer Engineering. 2009, 35(13): 137-138,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.047By using technology of blind signature and anonymous broadcast, and according to different structures of common vote and super ballot, the models of both of them are set up. The electronic voting scheme with super ballot is proposed, which makes privileged voters have the rights to vote super ballot, common ballot and abstention ballot. Experimental results show this scheme meets basic security of election scheme and is suitable for electronic voting in a small scale. It has the value of application.
-
Computer Engineering. 2009, 35(13): 139-140,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.048The basic concept and the key characteristic of braid groups are introduced. The existed problems in it are researched, such as the word problem, conjugacy problem, and root problem. By using these difficult problems, some kinds of code protocols are designed. On basis of it, and according to the exchangeability of subgroup elements in braid groups, a novel key authentication scheme based on p-th root problem and conjugacy research problem in braid groups is proposed. Simulation experimental results show this scheme is effective.
-
Computer Engineering. 2009, 35(13): 141-143. https://doi.org/10.3969/j.issn.1000-3428.2009.13.049Time stamp introduced on design of digital watermarking is an effective way to avoid the interpretation attack. This paper analyzes the shortcomings in the existing time stamp scheme and makes some improvement combined with bit commitment. On the premise of ensuring the security, the new scheme of time stamp reduces the robust pressure of digital works. The new time stamp scheme makes the digital watermarking more applicable.
-
Computer Engineering. 2009, 35(13): 144-146. https://doi.org/10.3969/j.issn.1000-3428.2009.13.050Micciancio-Warinschi(MW) method only studies two-party protocols with encryption primitive of public key and without messages of type type. Aiming at this problem, this paper uses public key encryption and symmetry encryption. It establishes extended label symbolic model and extended computational model, proves the computational soundness of the extended label symbolic model, and realizes the extension of MV method.
-
Computer Engineering. 2009, 35(13): 147-149. https://doi.org/10.3969/j.issn.1000-3428.2009.13.051This paper embeds the binary watermark information in carried image, computes the value of Normalized Correlation(NC) coefficient between query watermark and extracted watermark, and gains the retrieval results. The watermark algorithm is carried out in Discrete Cosine Transform(DCT) domain, and extracting process is instantaneous and blind. Experimental results show that this method based on digital watermark can protect the copyright and realize image retrieval.
-
Computer Engineering. 2009, 35(13): 150-152,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.052
Aiming at the problem that it is difficult for software to generate high-quality random number, this paper presents a random number generation algorithm based on parallel structure. This algorithm uses related systems and data buffering mechanisms. It uses the time difference of reading process and writing process to realize the dynamics of buffer region data and upgrade the quality of random number. Test results on random sequence generated by this algorithm show that its pass rate is higher than 99.7% in the NIST 800-22 standard.
-
Computer Engineering. 2009, 35(13): 153-155. https://doi.org/10.3969/j.issn.1000-3428.2009.13.053This paper discusses the hardware implementation of basic serial multiplier, parallel multiplier and series-parallel multiplier in Elliptic Curve Cryptosystem(ECC) systems, and proposes an improved multiplier based on divided algorithm. By dividing data into several subsets and cascading small multipliers to a larger one, this divided algorithm reduces the total clock cycles needed. It only takes 0.811 ms for a scalar point multiplication over GF(2233), which meets the requirement of ECC.
-
Computer Engineering. 2009, 35(13): 156-159. https://doi.org/10.3969/j.issn.1000-3428.2009.13.054This paper presents an analysis method of cryptographic protocol based on Object Oriented Timed Petri Nets(OOTPN), which uses the advantages of object oriented technology and timed Petri nets. This method can reduce the complication of modeling and computing, improve efficiency of modeling and realize high modularization of timed Petri nets. It can adapt to reunion and expansion during the analysis process of cryptographic protocol better. Results of instance analysis demonstrate that this method is valid.
-
Computer Engineering. 2009, 35(13): 160-162. https://doi.org/10.3969/j.issn.1000-3428.2009.13.055In order to improve the flexibility and practicality of multi-proxy and multi-signature, this paper proposes two new threshold multi-proxy and multi-signature schemes with property of message recovery based on Schnorr signature. The inhomogeneous members have unequal power, and only the designated verifier can recover the message and verify the signature. Analysis results show that the new schemes are secure under the discrete logarithm assumption and the random oracle model.
-
Computer Engineering. 2009, 35(13): 163-165. https://doi.org/10.3969/j.issn.1000-3428.2009.13.056Aiming at the geometric attack problem of the digital watermark, a novel algorithm is proposed based on the NonsubSampled Contourlet Transform(NSCT). Feature points are extracted by utilizing the characteristic of image from the greatly directional bandpass coefficients of the NSCT processed by binary. When watermark is detected, the feature points matching measure for the geometric manipulation is computed. The method can transform the image back to its original size/orientation, i.e, recover the lost synchronism. Experimental results show that it is robust to geometric attacks and other most common image processing manipulations.
-
Computer Engineering. 2009, 35(13): 166-168,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.057An Information Flow Analysis(IFA) algorithm in source code based on Static Single Assignment(SSA) intermediate representation is proposed. The process of covert channel recognition is introduced. The algorithm is implemented by using work table based on IFA. The characteristics of time and space cost and analysis accuracy are discussed. The analysis framework is inserted into GCC compiler. Simulation experimental results show this algorithm is effective, and has the value of application.
-
Computer Engineering. 2009, 35(13): 169-171. https://doi.org/10.3969/j.issn.1000-3428.2009.13.058This paper proposes a threshold multi-proxy blind multi-signature scheme based on elliptic curve by adopting threshold cryptography and blind signature scheme. The scheme solves how to generate blind signature while multiple proxy signers sign the message on behalf of multiple original signers. In order to improve the flexibility and practicality of the scheme, some original signers can cooperatively delegate their signing capability to proxy signers and some proxy signers can cooperatively generate the signature by adopting to verifiable secret sharing in the scheme. By analyzing the scheme, it concludes that the scheme has many security properties, such as blindness, untraceability, unforgeability etc..
-
Computer Engineering. 2009, 35(13): 172-173,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.059This paper proposes a Service Oriented Architecture(SOA) based DDoS defense framework to filter the anomaly flow in the source of the attack. By introducing SOA and overlay network, the framework remains loosely coupled with outside world and the bottom part of the framework is combined with encryption and decryption to construct a secure certification system. Experiments show that the framework can effectively protect normal client and service networks from malicious damage.
-
Computer Engineering. 2009, 35(13): 174-176. https://doi.org/10.3969/j.issn.1000-3428.2009.13.060A robust digital watermarking algorithm based on Zernike moments and DCT transformation is proposed, which estimates angles of rotation to promote the ability of anti-rotation attack. The orthogonal Zernike polynomials based on image content are made as watermarking signal, which is embedded into the middle or low frequence control by Watson’ perceptual model. Relevant detection method are used to identify the existence of watermarking. Experimental results show this algorithm has better performance of rubustness, nonvisibility, and testability.
-
Computer Engineering. 2009, 35(13): 177-178,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.061The likelihood ratio computation in Large Vocabulary Continuous Speech Recognition(LVCSR) systems based on continuou density Hidden Markov Model(HMM) is analyzed. The feasibility of using t parallel method to implement the likelihood computation is showed. On basis of this, a fast algorithm for likelihood ratio based on SIMD is proposed, which is implemented by improving likelihood computation modules in HTK3.4 toolkit. Experimental results show this algorithm can speed up the likelihood computation without lowering the accuracy rate of recognition of premise.
-
Computer Engineering. 2009, 35(13): 179-182. https://doi.org/10.3969/j.issn.1000-3428.2009.13.062Aiming at the slow convergence of DE/rand/1/bin strategy, this paper presents a hybrid optimization algorithm named SMDE incorporated Simplex Method(SM) into Differential Evolution(DE) algorithm. It takes use of good global searching ability of DE and good local searching ability and fast convergence of SM, so that the convergence speed and solution precision of DE are improved. Experimental results on several classical Benchmarks complex functions show that the hybrid optimization algorithm is effective, efficient and fairly robust to initial conditions, and its performances excels those single optimization methods.
-
Computer Engineering. 2009, 35(13): 183-185,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.063Smart home can provide users with active intelligent services due to its capability of pre-apperceive. This paper builds an ontology model of smart home, uses the inference interface of Jena to implement the basic inference of the context ontology, and filtrates the useless data by adding a context filter between inference layer and knowledge database. Experiment validates Rule-Based Reasoning(RBR) is feasibility and efficiency in smart home.
-
Computer Engineering. 2009, 35(13): 186-187,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.064The methods of extracting captions in news videos are always with low accuracy and efficiency, especially for caption text with low resolution and contrast. This paper proposes a detection method based on corner detection and adaptive threshold to solve the problems. It locates the text area based on corner detection, magnifies the image of text area, calculates the gray image and binaries it by using adaptive threshold and feedback method. Optical Character Recognition(OCR) are used to recognition the text in the binary images. Experimental results show that it is effective to extract the text with low resolution and contrast.
-
Computer Engineering. 2009, 35(13): 188-189,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.065This paper presents a spam filter approach based on Support Vector Machine(SVM) to deal with cross language E-mail including Chinese and English, which provides the ability of integrating more statistical information. It optimizes the representation of linear kernel to improve time complexity and storage complexity, and adopts domain term extraction to improve the ability of semantic unit recognition and the performance of spam filter. Experiments on large-scale cross language corpora show that SVM-based approach increases the precision by 6.13% compared to Naïve Bayes which is smoothed by Good-Turing, and increases classification accuracy by 8.18% compared to maximum entropy model.
-
Computer Engineering. 2009, 35(13): 190-192,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.066This paper proposes a new algorithm of TD(λ) based on factored representation. The main principle of the algorithm is that states are factored representation, and makes use of Dynamic Bayesian Networks(DBNs) to represent the conditional probability distributions in Markov Decision Processes(MDPs), together with decision-trees representation of value function in the algorithm of TD(λ) to lower the state space exploration and computation complexity. Therefore the algorithm is a promise for solving large-scale MDPs problems which are of a huge state space. Experiments demonstrates the validity of this representation method.
-
Computer Engineering. 2009, 35(13): 193-195. https://doi.org/10.3969/j.issn.1000-3428.2009.13.067Aiming at the walking stability of humanoid robot going down stairs, this paper presents a self-adaptive fuzzy control method based on Fictitious Zero Moment Point(FZMP). According to the restrains condition, the ankle and hip trajectory are generated. By using fuzzy controller, the position of reaction force on the surface is received. The trajectories are suitable modified according to the information of foot sensor. Simulation results show that this method can realize real-time control and high effect.
-
Computer Engineering. 2009, 35(13): 196-198. https://doi.org/10.3969/j.issn.1000-3428.2009.13.068A Cultural Algorithm(CA) is constructed for solving job shop scheduling problems. By means of simulating the evolution of culture in societies, the CA finds the final solution, with the mutual connection and promotion between the belief space and the population space in its computing progress. The algorithm employs fixed priority-list coding, its population space’s evolution adopts genetic algorithm, and its belief space’s creation and evolution depends on an unique belief-extraction method. A series of job-shop scheduling benchmark problems algorithm’s effect validates.
-
Computer Engineering. 2009, 35(13): 199-201. https://doi.org/10.3969/j.issn.1000-3428.2009.13.069The mining of product reviews is the process of extracting information in reviews which is expressed by natural language, the extraction of product feature is the first phrase of the mining of product reviews. The quality of product feature decides the quality of subsequent phrases. This paper adopts weakly supervised methods, which just need a hand of product features as the seeds, using the occurrence sentences of seed to extract text patterns, and using the text patterns to find new product features. Experimental results show that it can extract product feature from English plain text and receive good result.
-
Computer Engineering. 2009, 35(13): 202-204. https://doi.org/10.3969/j.issn.1000-3428.2009.13.070Using assumption of color invariance, basic optical flow equation based RGB color components is mapped to the field of wavelet. Complex value wavelet is used to produce over-determined system of equations and computes the optical flow in multi-resolution scheme. Complex value wavelet can also be used to reduce the effect of phase vibrating. The condition number of the linear system of equations composed by RGB color components is used to judge the reliability of the optical flow result. The reliable result is selected to be the final optical flow component value. Results of numeric experiments show that the method is efficient.
-
Computer Engineering. 2009, 35(13): 205-207. https://doi.org/10.3969/j.issn.1000-3428.2009.13.071In comparison with traditional optimization methods, evolutionary computation due to its intrinsic parallelism and some intelligent properties, such as self-organizing, self-adaptation, and self-learning. Evolutionary computation has been successfully applied to many fields. This paper proposes a Multi-Agent co-evolutionary algorithm, designs a new hybrid algorithm by combining evolutionary algorithm with some field-special strategies, and proves their efficiency by several experiments.
-
Computer Engineering. 2009, 35(13): 208-210. https://doi.org/10.3969/j.issn.1000-3428.2009.13.072The goal-driven idea is introduced into Agent/Group/Group(AGR) and a method for building the abstract organizational model of Multi-Agent System(MAS) from the AGR meta-model is proposed. The overview of AGR is given, and the steps and the corresponding formalization of the method are depicted in detail. It is applied to an intelligent fault diagnosis system. As is shown by practice, the method can effectively help designers build the organization-oriented MAS abstract organizational models directly starting with the AGR meta-model and it is suited for all kinds of AGR extension.
-
Computer Engineering. 2009, 35(13): 211-213. https://doi.org/10.3969/j.issn.1000-3428.2009.13.073Aiming at the disadvantage of the state-of-the-art CDF-9/7 wavelet that its filter coefficients are irrational, a class of Biorthogonal Interpolating Wavelets(BIW) parameterized by one free parameter is constructed based on the perfect reconstruction of the wavelet filter bank. By adjusting the free parameter, a new BIW is obtained, which has the advantages of both optimum coding gain and binary filter coefficients (numbers of the form ). Simulations show that the new wavelet exhibits image compression performance competitive to CDF-9/7, and the corresponding lifting based Discrete Wavelet Transform(DWT) gains improvement upon computing efficiency superior to 50%.
-
Computer Engineering. 2009, 35(13): 214-215,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.074Wavelet coefficients of real signal have strong relations, while the dependence of coefficients of noise is more weaker. On the other hand, large wavelet coefficients contain the information of image edge. Considering the relationship of intrascale and maxima coefficients, two new dependence coefficients are proposed. Experimental results show that the new denoising method performs better both in denoising and preserving texture, compared to the traditional denosing metohd based ondependence coefficients.
-
Computer Engineering. 2009, 35(13): 216-218,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.075This paper proposes a time-frequency filtering method based on S transform. S transform inherits the advantages of the wavelet transform and short time Fourier transform. It is suitable for medical image processing. This method uses hard threshold for de-noising in local spectrum, and can be used in image de-noising of the Myocardial Contrast Echocardiography(MCE). Experiment of de-noising demonstrates its validity and clinical application value.
-
Computer Engineering. 2009, 35(13): 219-221. https://doi.org/10.3969/j.issn.1000-3428.2009.13.076White Block Skipping(WBS) coding, which uses the character that binary images contain a large amount of white area, can make a great decrease in the information of white pixels to get low bit rate. But the compressing multiples of images those contain more blacks are not good because black pixels have not been compressed. This paper proposes a better way called adaptive block skipping for this limitation. The new approach will do compression also to the blacks by the new adaptive black block skipping in the scan lines those have more black than white. Experiments show that better multiples can be gotten by using this new method to images those contain much more blacks.
-
Computer Engineering. 2009, 35(13): 222-224. https://doi.org/10.3969/j.issn.1000-3428.2009.13.077On the base of the theory of rate distortion, the new idea of macro block mode about inner and mutual compiling frame is presented in this paper, and the MSE distortion computation model is built. This method can acquire the optimal control point in the rate-distortion curve under the code error environment from the global optimization perspective, not only self-adaptive adjust the quantization parameter under given network bandwidth but also refresh inner macro block frame according to the current probability of loss of network package, and plays an important effect in counteracting the channel code error, which has a good reference value in the way of transmitting robust video code in wireless environment and allocating resource.
-
Computer Engineering. 2009, 35(13): 225-227,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.078A key frame extraction algorithm based on Shot Content Change Ratio(SCCR) is proposed against miss or redundancy when using single threshold to extract key frames from video with moving objects. Shot Content Change Ratio is defined according to the variation of the sum of shot adjacent frame difference and the average shot adjacent frame difference. High and low thresholds are determined by the ratio, and a single or several key frames can be extracted from a shot. Experimental results show that this ratio can better describe video frames’ content change and key frames extracted are representative.
-
Computer Engineering. 2009, 35(13): 228-231. https://doi.org/10.3969/j.issn.1000-3428.2009.13.079Motion estimation is a core technique of video coding technique. This paper proposes a fast motion estimation algorithm called spatiotemporal correlation adaptive search. The property of the motion vector is analyzed, and an adaptive stop criterion is introduced to detect the stationary macroblock, thus terminating current search immediately. The initial search center is selected adaptively. Two search strategies are adopted adaptively according to spatial correlation(whether the local motion activity is high or low). Adaptive threshold for half-stop is proposed. Experimental results shows that the proposed algorithm provides faster speed and higher precision than most existing fast block-matching algorithm, while the distortion is almost the same as FS.
-
Computer Engineering. 2009, 35(13): 232-233,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.080Voice Activity Detection(VAD) algorithm based on multiresolution spectrum is presented. The proposed VAD uses MFCC of multiresolution spectrum and two classical audio parameters as audio feature, and prejudges silence by detection of multi-gate zero cross ratio, and classifies noise and voice by Support Vector Machines(SVM). Experimental results show that the proposed VAD algorithm achieves overall better performance in all SNRs than VAD of G.729b and other VAD based on MFCC, and computation of micro controller unit based on proposed VAD is lower than that based on G.729b VAD.
-
Computer Engineering. 2009, 35(13): 234-236. https://doi.org/10.3969/j.issn.1000-3428.2009.13.081AVS-S standard is a new audio and video standard for video surveillance application. Spatial scalability meets the requirement of changeable resolution bit streams. To improve the coding efficiency, this paper designs tow arithmetics inter-layer prediction for AVS-S based on SVC spatial scalability approach: base layer up-sample re-prediction and inter-layer and inter layer spatio-temporal MV prediction. Simulation result shows that the proposed algorithm is convenient in implementation and excellent in performance.
-
Computer Engineering. 2009, 35(13): 237-239. https://doi.org/10.3969/j.issn.1000-3428.2009.13.082According to the communication and control requirement of multi-channel Controller Area Net(CAN) bus by the HLA simulation platform, this paper describes an embedded PowerPC system based method of design and implementation of multi-channel CAN communication platform. The corresponding Linux multi-channel CAN device driver is also developed. This flexible system can connect to different number of CAN daughter boards. It can work stable with low CPU usage under the condition of high data rate on multi channels.
-
Computer Engineering. 2009, 35(13): 240-242. https://doi.org/10.3969/j.issn.1000-3428.2009.13.083With the development of industrial automation, communication between OLE for Process Control(OPC) applications in heterogeneous platforms becomes a frequent issue in industrial process control area. This paper describes three methods, using EntireX DCOM/Java/XML OPC respectively to develop OPC clients under Linux. OPC client on Linux platform is able to communicate with OPC server on Windows platform, which is a successful implementation of OPC cross-platform communication. Key technologies in each method are discussed and corresponding code is also included with explicit explanation. A comparison is made between all implementations, based on which their further application in industrial environment is evaluated.
-
Computer Engineering. 2009, 35(13): 243-245. https://doi.org/10.3969/j.issn.1000-3428.2009.13.084Aiming at the enhancement of the complexity of control arithmetic and the limited disposal ability of embedded industry controller, this paper brings forward the design of fast control system, which is based on Digital Signal Processor(DSP) and PMC bus, including the instauration of a general and standard hardware platform mainly with DSP, dual-port RAM, PCI bridge and CPLD chips, and the design of the device driver of PMC bus on VxWorks operating system. Parallel disposal system based on DSP and embedded industry controller is proved to be able to realize complex control arithmetic and digital process method, which can improve real time performance and precision of whole system effectively.
-
Computer Engineering. 2009, 35(13): 246-248,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.085Aiming at the actuality of the core control system for the dispenser and the challenge from technology developing and requirement from market, the design of a new generation of dispenser control system is introduced. ARM and embedded Linux operating system is used to construct the based running platform, and the modularized hardware platform is designed based on CAN bus, and the different processes, which communicate with each other via Intertask Communication and Services(ICS) are developed to implement for the main task. It proves the new designed controller can not only support four nozzles fueling, but also make the dispenser more intelligent, open and maintainability, and the cost is lower.
-
Computer Engineering. 2009, 35(13): 249-251. https://doi.org/10.3969/j.issn.1000-3428.2009.13.086Considering the specificity in the specific realization of interrupt in the VxWorks, this paper proposes an interrupt treatment design of a system consisted of multiple data acquisition boards. It divides the traditional Interrupt Service Routine(ISR) into interrupt service routine and interrupt service task, and makes use of the semaphore to synchronize them. By introducing the priority that users define, the design enhances the real-time performance and stability of the system.
-
Computer Engineering. 2009, 35(13): 252-254. https://doi.org/10.3969/j.issn.1000-3428.2009.13.087This paper develops a novel portable asphalt pavement test system with USB bus. According to the infrared radiation characteristics of asphalt material, infrared thermocouple senor is applied to testing paving temperature of asphalt by non-touched infrared ray, while capacitive fence displacement senor based on principle of relative areas change is applied to test paving thickness. The output of senor is sent to the expend system with the control core of single chip microcomputer AT89C52, which realizes A/D conversion, data storage, data display and data transmission. The application software installed in the notebook PC makes a fast processing and analysis of the data transferred by USB bus.
-
Computer Engineering. 2009, 35(13): 255-257. https://doi.org/10.3969/j.issn.1000-3428.2009.13.088Aiming at settling a range of issues, such as data consistency, deployment of experiment source, loading of initial situation, monitoring of simulation function, experiment data recovery and so on, which distributed simulation faces. This paper proposes a distributed simulation experiment management system architecture. The goal of architecture is to meet weapons and equipment demonstration on the demand for data samples, assistant weapons and equipment demonstration persons to edit scenario, design experiment, plan experiment, monitor experiment. Its establishment makes distributed simulation technology better serve the weapons and equipment demonstration.
-
Computer Engineering. 2009, 35(13): 258-260,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.089Aiming at the deficiency of music representation in existing Digital Music Libraries(DML), this paper presents a novel architecture of DML based on Web2.0, which supports interactive learning about music content data and music features effectively. A DML prototype, MusicSpirit, is implemented based on the above architecture, which brings forth music data by Ajax and Web2.0 techniques. Experimental results show MusicSpirit can improve the quality of digital music education efficiently.
-
Computer Engineering. 2009, 35(13): 261-263,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.090Electronic commerce logistics distribution service level is uneven. It is a complex process that customer chooses satisfied logistics service provider. This paper constructs Agent-based calculation experiment to simulate the selection process of logistic service provider. It establishes the flow and the frame of electronic commerce logistics distribution performance level appraisal and provider selection. It also establishes the evaluating and selecting model based on multi-Agent with Swarm, and gives an example of relationship between logistics distribution service level and client size.
-
Computer Engineering. 2009, 35(13): 264-266,. https://doi.org/10.3969/j.issn.1000-3428.2009.13.091Aiming at existing methods can not work under a large frequency offset, this paper proposes a carrier frequency offset estimation method for Digital Terrestrial Multimedia Broadcasting——DTMB system. It utilizes structural trait of signal frame in international system, employs power detection and three steps of estimation to complete the frequency offset estimation. Compared with traditional frequency estimation methods of DTMB system, the merit of proposed method works well under a large frequency offset. Simulation results indicate that the proposed method exhibits good performance under the situation of ±400 kHz carrier frequency offset in AWGN channel. It can completely satisfy the request of DTMB system in AWGN and multipath channels.
-
Computer Engineering. 2009, 35(13): 267-270. https://doi.org/10.3969/j.issn.1000-3428.2009.13.092Aiming at the issues of agility, flexibility and distributed characteristics of the knowledge management of the Virtual Research Center(VRC), a comprehensive model of the Knowledge Management System(KMS) of the VRC based on Web Service is proposed. According to the model predictions, the KMS of the VRC of Yalong river hydropower development is built and the corresponding functions of components are described. The results show that it is an effective way for the VRC to realize sharing, communication and innovation of knowledge through building a KMS based on the proposed model, which has characteristics of reliability and feasibility.
-
Computer Engineering. 2009, 35(13): 271-273. https://doi.org/10.3969/j.issn.1000-3428.2009.13.093Aiming at shortcomings of slow response and poor user experience existing in the traditional WebGIS application, this paper presents a new WebGIS design framework with core AJAX technology of Web2.0 and XML data transfered in the Web application. Based on Google Maps platform, the application uses the XMLHttpRequest objects which call the XML data and load the geographic information dynamically. Applied result proves, the scheme improves the efficiency of WebGIS application, it can be accessed quickly, customized and extended, and make asynchronous requests between the browser and the server.
-
Computer Engineering. 2009, 35(13): 274-276. https://doi.org/10.3969/j.issn.1000-3428.2009.13.094Aiming at the problems existing in collection part of traditional farm field meteorological information remote monitoring system, such as difficult routing, high cost and distance limitation, this paper presents a scheme of wireless network collection node based on GSM with its wide covering, rapid and low price, and describes hardware architecture, communication principle and software implementation. The experiment shows that the system is reasonable and feasible, it can realize timely collection, stable transmission and real-time alarm of farm field meteorological information．
-
Computer Engineering. 2009, 35(13): 277-279. https://doi.org/10.3969/j.issn.1000-3428.2009.13.095In Pub/Sub(P/S) system that supports mobile clients, aiming at event loss and high time cost in durable subscription events recover, this paper proposes a fast durable subscription event recover algorithm. The algorithm imposes forwards events fetching command and integrates respread and resubscription into buffered events fetching, optimizes buffered events forwarding. Algorithmic analyses and experimental result show the algorithm guartees the integrality of event, decreases the events recover time, and reduces the range of messages forwarding.
-
Computer Engineering. 2009, 35(13): 280-282. https://doi.org/10.3969/j.issn.1000-3428.2009.13.096Aiming at the problems of suppressing multi-access interferences in direct sequence code division multi-access system, this paper proposes a constant modulus blind multi-user detection algorithm of momentum dithered signed-error by adding momentum to fasten convergence speed, and its convergence is theoretically proved. Result that it compares with other algorithm by computer simulation shows that it obtains better convergence tracking and robustness properties.
-
Computer Engineering. 2009, 35(13): 283-封三. https://doi.org/10.3969/j.issn.1000-3428.2009.13.097Aiming at the integration problems of flow data for complex business environments, this paper proposes a flow integration model which comprises a event driven, multi-business interfaces, multi-communication and highly customizable based on a flow controlling method of instant communication under complex business environments. It introduces the streamline conception for service enterprises to improve flow efficiency. The model can solve the problem of flow management in the insurance business.
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