20 February 2012, Volume 38 Issue 04
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Computer Engineering. 2012, 38(04): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2012.04.00This paper presents a new tree-modeling approach based on Light Detection and Ranging(LiDAR) data with improved L-system algorithm. Some extend of the parameters are made and randomization is compared with the traditional functions. The laser points are used to extract the algorithm parameters and analyze the tree characteristics. The function’s result is a reconstruction of the 3D tree model which has similar features with laser points and values of tree height, crown diameter. Experimental results validate the approach provides ideal results and plays an important role in LiDAR application to the 3D GIS, virtual reality and field of forestry.
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Computer Engineering. 2012, 38(04): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2012.04.002Aiming at the safety problems of identity anonymity in electronic auction, a safe and efficient scheme is designed based on secret sharing idea, which uses double digital signature to guarantee the safe information transfer among the parties. The bidder is covered by a temporary identity and the bid is send to others indirectly. The auction server can speculate the winner by arranging the figures calculated by a monotone increasing function. If the results from the auction server and the register manager are the same, the winner can be declared. Safety analysis result shows that the proposed scheme is not only secure but also simple and efficient.
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Computer Engineering. 2012, 38(04): 7-9. https://doi.org/10.3969/j.issn.1000-3428.2012.04.003Aiming at the problems of low transmission rate and the interference introduced to the primary user by cognitive users, this paper proposes a cognitive relay selection algorithm based on location and interference constraint, the relay is chosen according to the relation between the location of cognitive relay nodes and the transmission rate of the relay link, and the optimal transmitting power is determined under the interference restraint of cognitive users to primary users. Simulation results show that the algorithm can both increase the throughput and restrict the interference of cognitive users to primary users successfully.
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Computer Engineering. 2012, 38(04): 10-13. https://doi.org/10.3969/j.issn.1000-3428.2012.04.004This paper establishes a model of schedule based on multi-agent for the production process of a process industry workshop, and analyses the relationship among agents. A multi-stage single-issue bilateral negotiation model based on the consultation of game theory among agents is built to solve the schedule problem with the objective of process flow or output of product. Simulation results of diaphragm caustic soda production schedule example show the feasibility and effectiveness of the model.
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Computer Engineering. 2012, 38(04): 14-16. https://doi.org/10.3969/j.issn.1000-3428.2012.04.005In allusion to the problem of interference to the skeleton extraction of different human posture, a new algorithm of skeleton extraction is presented. Through the combination of the depth information based on sagittal plane of 3D human model with improved Hopfield neural network, the rate of convergence speeds up by using a new input-output function of network to improve traditional human skeleton extraction algorithm. The network gets away from local minimum successfully and decreases the running time of network which is decided to depth information of feature points. Experimental result shows that the displacement on skeleton feature points using new algorithm is obvious less than that of traditional algorithm. In addition, the computation time is decreased. Therefore, the new algorithm has better effect on human skeleton extraction.
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Computer Engineering. 2012, 38(04): 17-19. https://doi.org/10.3969/j.issn.1000-3428.2012.04.006In BtoC e-commerce logistics distribution activities, many distribution companies using outsourcing vehicles and the drivers have working time limit. On the basis of this, this paper proposes an Open Vehicle Routing Problem with Time Windows and Working Time (OVRPTWWT), and constructs its mixed integer planning model. A clonal selection algorithm for OVRPTWWT is proposed, it improves the antibodies updating procedure, restraining tactics and designs a new clonal selection method for the algorithm. An example verifies the efficiency of the model and algorithm.
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Computer Engineering. 2012, 38(04): 20-22. https://doi.org/10.3969/j.issn.1000-3428.2012.04.007In process control system, in order to identify potential security problem, the analysis technology of Hazard and Operability(HAZOP) is proposed. The technology is developed in the chemical industry, HAZOP analysis can also be employed successfully in computer process control system. In this paper, the procedure of HAZOP analysis is described, followed by the study on the selection of items and the use of parameters and guide words in computer process control systems. The method is illustrated by a case study for the computer control of chemical process system.
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Computer Engineering. 2012, 38(04): 23-27. https://doi.org/10.3969/j.issn.1000-3428.2012.04.008In terms of the requirement of ID authentication in trusted computing filed, this paper proposes a Trusted Platform Module(TPM)- based strong ID authentication protocol. TPM is reviewed as well as the types of keys supported and their relationship. A mathematical model of the protocol using the formal method of process theory is designed. The extension of the protocol is discussed, including Platform Configuration Register(PCR) challenging and implementing platform independence. An application scenario of the protocol by network development technology is implemented. Experimental results show the protocol can authenticate users’ ID effectively.
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Computer Engineering. 2012, 38(04): 28-30. https://doi.org/10.3969/j.issn.1000-3428.2012.04.009Operation and control of remote sensing data processing system on ground faces the challenges of many sensors and complicated processing algorithms, and suffers lack of uniform workflow management. Aiming at the difficulty, this paper issues a universal model of operation and control combined with workflow technology, which completely separates business logic from control logic, simplifies the structure and programming model of the system, and satisfies various resource requirements of processing algorithms by using job management system. Experimental results show that the operation and control system achieves rapid response. The job response time is about 0.3 second at system idle time, and with the increasing of system workload, the delay of operation and control has no remarkable change.
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Computer Engineering. 2012, 38(04): 31-34. https://doi.org/10.3969/j.issn.1000-3428.2012.04.010Grating ruling engine, which is used to manufacture the master grating, directly determines the final quality of the production of grating. In this paper, co-simulation based on virtual prototype replaces the traditional physical prototype development. mechanical dynamic analysis software Pro/Engineer and control simulation software are used to build a grating ruling engine of mechanical dynamic model and controller model respectively. The mechatronics simulation is achieved and from the simulation result, the control parameter is determined. Using this method, cost is reduced and the efficiency of research is improved.
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Computer Engineering. 2012, 38(04): 35-36. https://doi.org/10.3969/j.issn.1000-3428.2012.04.011On the basis of the research and analysis of CAN network diagnostic protocol and automotive diagnostic structure, in-vehicle network diagnosis is designed and developed. The design and development of diagnostic tool is realized through VC software development platform and USBCANII hardware interface. System test result shows that communication process of the designed diagnostic system conforms to diagnostic standard. The developed low cost diagnostic tool is applied well on developing and testing ECU with diagnostic function.
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Computer Engineering. 2012, 38(04): 37-39. https://doi.org/10.3969/j.issn.1000-3428.2012.04.012This article studies the recognition of the temporal relation between an event and a time expression and the temporal relation between two events where one event syntactically dominates the other event in one sentence. It analyzes some effective linguistic features such as dependency parsing information, relative positions, signal words, position of signal words and so on. A method based on maximum entropy model is proposed. In addition, how linguistic features could affect temporal relation recognition is analyzed. Experimental results show the accuracies of the two tasks are respectively 87.83% and 80.79%.
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Computer Engineering. 2012, 38(04): 40-42. https://doi.org/10.3969/j.issn.1000-3428.2012.04.013Aiming at data redundancy problems appeared in the data collection process of Beidou user machine position, the paper analyzes the reason caused by data redundancy. Compression algorithm of redundant data based on time series clustering is proposed. The algorithm which adopts the clustering method based on density puts the data sets into the same cluster, which have the same movement characteristics. According to the cluster diameter to determine whether the cluster is redundant data, then compress the redundant data. Experimental results show the algorithm can correctly identify the redundant data and implement data compression.
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Computer Engineering. 2012, 38(04): 43-45. https://doi.org/10.3969/j.issn.1000-3428.2012.04.014It analyzes the AUTOSAR conformance test process. The AUTOSAR conformance test based on TTCN-3 test system architecture has been achieved using the tools such as eclipse, TTthree and μTTman. The functions of test suite, codec and adapter of testing system and their implementation have been discussed for simple blinker system. The article verifies the feasibility of AUTOSAR conformance test using TTCN-3.
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Computer Engineering. 2012, 38(04): 46-48. https://doi.org/10.3969/j.issn.1000-3428.2012.04.015Attribute reduction is the basic problem of rough sets theory. A method for minimal attributes reduction in consistent decision table is proposed in this paper. The discernible information in consistent decision tables is described with discernible vector array. A minimal attribute reduction tree is generated based on the probability of the attributes which discern two objects. All minimal attribute reductions are got from minimal attributes reduction tree. The result of the method is proved to be complete and minimal.
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Computer Engineering. 2012, 38(04): 49-51. https://doi.org/10.3969/j.issn.1000-3428.2012.04.016Current recommendation methods lack of ability to evaluate utility of the recommendations according to user’s preferences. So users have to make a choice among recommendations. On the basis of this, this paper presents a personalized recommendation method based on utility according to user’s preferences. This method uses TOPSIS to evaluate utility of recommendations. In order to overcome the shortcoming of static weight in TOPSIS, it adopts variable rough set to discover user’s preference for attributes. Experimental results show that the method can provide more appropriate recommendation service with better utility for users.
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Computer Engineering. 2012, 38(04): 52-54. https://doi.org/10.3969/j.issn.1000-3428.2012.04.017This paper presents a Deep Web data sources discovery method based on ontology. It uses webpage classification, form structure classification and form content classification to find Deep Web querying interface in some fields. It proposes that semi-automatic construction and automatic extension of ontology are added to the webpage and form content classification, and heuristic rules are enriched in the form structure classification. Experimental results show that this method can improve the precision and recall of Deep Web database discovery effectively.
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Computer Engineering. 2012, 38(04): 55-57. https://doi.org/10.3969/j.issn.1000-3428.2012.04.018There are lots of rules and data in the logic of software, whose definition and modification are consuming. To overcome the above problems, a software platform based on user-defined rule is proposed in the paper, which can manage and interpret rules in different styles and data from different resources. Aiming at flexibility of software business rules, the platform thinks of rules of business logic, combines the characteristics of changing of software demands and orients modules including data dictionary, knowledge base and interpreter. Through the above research, a software platform convenient for demand changing is implemented which improves the efficiency of development and maintenance for software.
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Computer Engineering. 2012, 38(04): 58-59. https://doi.org/10.3969/j.issn.1000-3428.2012.04.019This paper gives a proof to the feasibility of the heuristic attribute reduction in simplified information system. It points out the results of one quick algorithm may contain redundancy attributes and time complexity calculation is wrong. This paper proposes a heuristic algorithm of attribute reduction based on universe compression. The relative support degree is used as heuristic information for reducing the searching room. A process of secondary reduction is used in order to eliminate redundancy attributes. A real example results demonstrate the improved algorithm has good reduction effect.
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Computer Engineering. 2012, 38(04): 60-62. https://doi.org/10.3969/j.issn.1000-3428.2012.04.020This paper analyzes the difficulty and research status of Service Oriented Architecture(SOA) test and proposes an SOA test method based on business data in large enterprise. A large number of real history business data are input into the integrated environment, and a comparison table is used to test the outputs of services and business processes. Case analysis shows that the method is operable in action, and suitable for testing SOA in large enterprise.
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Computer Engineering. 2012, 38(04): 63-66. https://doi.org/10.3969/j.issn.1000-3428.2012.04.021To obtain the effective distribution of metadata and load balance of the multi metadata servers, this paper presents a dynamic management system of distributed metadata, which makes use of load balancing algorithms to select some appropriate subtrees, then uses migration strategy to migrate these subtrees to proper metadata servers, and utilizes replication strategy to reduce the load of the metadata server which is produced by reading metadata operation. Experimental results show that the system can obtain the effective distribution of metadata.
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Computer Engineering. 2012, 38(04): 67-69. https://doi.org/10.3969/j.issn.1000-3428.2012.04.022Aiming at the classification of the skewed dataset, this paper proposes an improved over-sampling algorithm of minority class sample, named B-ISMOTE. It improves the data unbalanced distribution of degree through randomized interpolation to produce virtual minority class instances in the sphere space, which constitute of the borderline minority class instances and its nearest neighbor. Experimental results on the real datasets show that compared with SMOTE algorithm and B-SMOTE algorithm, B-ISMOTE algorithm has better classification performance.
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Computer Engineering. 2012, 38(04): 70-72. https://doi.org/10.3969/j.issn.1000-3428.2012.04.023In order to figure out how memory faults affect high-performance servers, this paper presents a multi-layer fault injection method for Itanium architecture computers. HMFI(Hierarchical Memory Fault Injector) is designed and developed to inject memory faults in physical level, operating system kernel level and process level. Experimental results demonstrate the effectiveness of HMFI in evaluating the fault-tolerant properties of complex computer system.
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Computer Engineering. 2012, 38(04): 73-75. https://doi.org/10.3969/j.issn.1000-3428.2012.04.024In the dense database, mining maximal frequent itemsets takes too much time, and the results are too large to satisfy the users. This paper proposes a maximal frequent itemsets mining algorithm, called VCM. It filters the database with the constraints, uses the vertical data representation of data sets and adopts depth-first strategy for mining maximum frequent itemsets. Compared with other algorithms, experimental results show that the VCM algorithm is faster and more effective, and the advantage is remarkable when the databases are dense and with long patterns.
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Computer Engineering. 2012, 38(04): 76-78. https://doi.org/10.3969/j.issn.1000-3428.2012.04.025To resolve the semantic conflicts in the process of data exchange, an improved semantic conflict resolution scheme is presented. It uses ER model to realize the semantic mapping from relational schema to XML Schema, and uses ontology to make semantic annotations on XML Schema which is translated semantically and preliminary. Experimental results show that this scheme can reduce the ambiguity caused by the difference of natural language or symbol, semantic conflicts between the heterogeneous data sources are resolved to some extent.
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Computer Engineering. 2012, 38(04): 79-81. https://doi.org/10.3969/j.issn.1000-3428.2012.04.026This paper defines a new self-resolving message protocol called HML by departing self-description area and data area. This protocol has limitations of the layers of description area. It can raise the efficiency of resolving and solve the problems between the lays of large scale processing system. The feature is proved to be true compared with XML and ISO8583, and the protocol can be used in communication between layers in high concurrent process system.
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Computer Engineering. 2012, 38(04): 82-83. https://doi.org/10.3969/j.issn.1000-3428.2012.04.027To handle the Simple Continues Near Neighbor Chain(SCNNC) query in dataset, the method based on the Voronoi diagram is proposed. The definition of SCNNC query is given and many data points are deleted based on the properties of the Voronoi diagram. The algorithm which can accurately query the simple continues near neighbor chain in dataset is put forward. Experimental results show that with the increasing numbers of the points in the simple continue near neighbor chain, the method has more advantages than the method based on R tree.
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Computer Engineering. 2012, 38(04): 84-87. https://doi.org/10.3969/j.issn.1000-3428.2012.04.028For the problem of multi-coverage under the case that the sensor nodes are high-density deployed in Wireless Sensor Network(WSN), this paper proposes a k-covering algorithm based on Voronoi diagram. This algorithm uses the information of neighbors nodes to establish the set called Voronoi Coverage Neighbor(VCN) node set, then builds a directed graph reflecting the relationship of the coverage. According to the requirement coverage of network, adjusts the state of nodes to achieve K coverage. Simulation results show that the algorithm can correctly determine the network coverage, and the number of approximate minimum active nodes is superior to Coverage Configuration Protocol(CCP) algorithm.
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Computer Engineering. 2012, 38(04): 88-91. https://doi.org/10.3969/j.issn.1000-3428.2012.04.029In order to satisfy diverse quality of service in the heterogeneous P2P streaming systems, by making use of the advantages of network coding, a P2P streaming network coding and data scheduling method based on Fine Granularity Scalability(FGS) is proposed. By network coding grading and node rank management, it makes the heterogeneous nodes operate cooperatively with each other, and achieves the distributed data schedule strategy in unstructured P2P system. Simulation results demonstrate that the proposed method is capable of maintaining playing continuity degree close to 1.0 and has noticeable advantages over conventional scheduling method, especially under particular conditions such as low access bandwidth, small buffer and playback time delay and so on.
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Computer Engineering. 2012, 38(04): 92-94. https://doi.org/10.3969/j.issn.1000-3428.2012.04.030It is difficult to set reasonable output bandwidth in dynamic network for Explicit Control Protocol(XCP), and unreasonable settings of bandwidth will cause the link utilization declining, so this paper proposes a compensation algorithm of XCP bandwidth named FC-XCP. By reasonable controller design, it solves the problem of bandwidth mismatching when the XCP dynamic changes. Simulation experimental results show that compared with PII-XCP, FC-XCP can improve the bandwidth utilization effectively in dynamic networks.
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Computer Engineering. 2012, 38(04): 95-96. https://doi.org/10.3969/j.issn.1000-3428.2012.04.031Existing epidemic spread models are only used in unitary failure and homogeneous network. Aiming this problem, this paper presents a multiple failure spread model in Generalized Multiprotocol Label Switching(GMPLS) network. This model assign node functions into two planes: control plane and data plane. The math formulation for finding the epidemic threshold is given. Extensive simulations is carried out on different network topologies, the results are approach to the theoretical values, which show this model is exact.
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Computer Engineering. 2012, 38(04): 97-99. https://doi.org/10.3969/j.issn.1000-3428.2012.04.032It can not directly observe the structure of the ZigBee Wireless Sensor Network(WSN) as the wired networks. This problem makes it difficult to manage and control the ZigBee WSN. To solve this problem, a discovering ZigBee wireless sensor network topology algorithm called ZigBeeTopo is proposed to determine active network nodes and their relationship. By designing the wireless sensor networks topology manage module, it can make the ZigBee network topology visible. Test results show that this algorithm can discover variety of wireless sensor network topologies correctly.
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Computer Engineering. 2012, 38(04): 100-103. https://doi.org/10.3969/j.issn.1000-3428.2012.04.033This paper proposes a Chord model(Ant-Chord) which has an ability of physical topology matching to store the mapping information of identifiers. The ideas of Ant-Chord is to regard the storage nodes in the whole Chord as a TSP problem and solve the TSP problem quickly by using the ant colony algorithm, then to build the Chord with the obtained Traveling Salesman Problem(TSP), and proposes a method which called Luoyang Shovel Method(LSM) to optimize the Ant-Chord’s routing hops. The model is simple and easy to implement, which has small changes within the original Chord model and little extra overhead cost in the routing table storage. Simulation results show that Ant-Chord has obvious advantages in average routing hops and delay in comparison with other Chord models.
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Computer Engineering. 2012, 38(04): 104-107. https://doi.org/10.3969/j.issn.1000-3428.2012.04.034High delay time, extensive retransmission times and failure of adapting the large scale of Wireless Mesh Network(WMN) are the major problems of the existing Layer-BLBP protocol of WMN. To address these problem above, this paper presents a multicast error correction protocol based on chip. Every node has its unique and orthogonal chip in proposed protocol, then encrypt the data using their chip, so it can share the channel. Simulation results show that this protocol preserves comparatively less delay time and retains relatively fewer transmission times than the original LBLBP in high error rates environment by the simulating result.
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Computer Engineering. 2012, 38(04): 108-109. https://doi.org/10.3969/j.issn.1000-3428.2012.04.035Maximum decodable linear network code can improve the network capacity, but there are problems in the situation of edge false or node false. Based on greedy algorithm and a heuristic rule, this paper proposes an algorithm to construct the static maximum network coding. In each iteration process, it adds an existing vector, and deletes the edge used. Simulation result shows that the proposed algorithm can obtain great gain in network capacity.
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Computer Engineering. 2012, 38(04): 110-111. https://doi.org/10.3969/j.issn.1000-3428.2012.04.036Because of the fast change in mobility and topology, the performance of traditional wireless network routing protocols declines seriously in Vehicular Ad Hoc Network(VANET). Aiming at this problem, this paper improves AODV algorithm, takes the vehicle mobility information into account, and proposes an improved routing algorithm. The algorithm takes full use of position and velocity information. By estimating and calculating the possible duration of links, the Possible Length Expiration Time(PLET), the path with longest duration is selected. This algorithm is designed to decrease the time for route discovery by setting the timer and searching the path paralle. Extensive simulation results show that the algorithm has better throughput, transmission rate and lower delay compared to AODV algorithm.
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Computer Engineering. 2012, 38(04): 112-115. https://doi.org/10.3969/j.issn.1000-3428.2012.04.037For most of chaotic image encryption algorithms, pixel overall treatment method(such as XOR operation) is used in the image pixel value scrambling. It was very weak to resist known cleartext attack. So a high dimension chaotic encryption based on discrete Hopfield network is proposed in this paper. Image pixel value scrambling is realized through dynamic adjustment of each bit’s scrambling weight and threshold depending on any two dimensions of R?ssler 3D chaotic sequences. Image pixel position scrambling is realized depending on the third dimension of R?ssler 3D chaotic sequences. Each pixel value scrambling is a composite treatment, it increases decryption difficulty. Experimental results show that the algorithm has strong ability to resist attacks, and is a security image encryption algorithm.
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Computer Engineering. 2012, 38(04): 116-118. https://doi.org/10.3969/j.issn.1000-3428.2012.04.038This paper proposes a cover image sharing steganographic algorithm based on the Bernstein polynomial for the problem of small steganography capacity and poor security of image sharing. It constructs image sharing steganographic model, describes the properties of Bernstein polynomial and proves sharing principle. Algorithms of embedding and extraction are given, experiments of image sharing steganography and anti-attack are completed. Experimental result and analysis show that the algorithm increases embedding capacity, reduces the perceived quality of cover image and improves security of secret information.
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Computer Engineering. 2012, 38(04): 119-121. https://doi.org/10.3969/j.issn.1000-3428.2012.04.039Aiming at the problem of divide-and-conquer attacking on the low-dimensional chaotic system, a new image encryption algorithm based on multidimension chaotic system is proposed. Such as Arnold, Ushiki and 3D Lorenz map, on the basis of the research on different chaotic maps, it achieves the structure of more overall rounds of confusion stage and a single diffusion stage. It contains pixel confusion and the key stream, as well as the way of encryption operator generation. Experimental results show that the proposed algorithm can get excellent encryption effect, high security performance, and strong attack against ability.
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Computer Engineering. 2012, 38(04): 122-125. https://doi.org/10.3969/j.issn.1000-3428.2012.04.040Return-oriented Programming(ROP) is a new attack based on code-reuse technique. This paper proposes a dynamic runtime detection system for return-oriented programming attack, studies the intrinsic nature of ROP and its variant. According to these nature, it designs ret integrity checking, call integrity checking and jmp integrity checking. The detecting system is implemented to static instrument and dynamic run-time checking. Static instrument assemble the analysis code into the program to be detected and dynamic run-time checking do the real detection with the three integrity checking. Preliminary experimental results show that the method can efficiently detect ROP malicious code and have no false positives and negatives.
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Computer Engineering. 2012, 38(04): 126-128. https://doi.org/10.3969/j.issn.1000-3428.2012.04.041In order to protect privacy of biometric data in remote authentication, a protocol is presented for private two-party set intersection problem with Universally Composable(UC) security by using smart cart. The proposed protocol uses only a linear number of symmetric-key computations and thus achieves high efficiency on computation and communication. A remote authentication scheme is furtherly designed based on the proposed protocol, which allows a server securely matching the query fingerprint of a user against the stored template to verify his identity, without leaking these private data.
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Computer Engineering. 2012, 38(04): 129-133. https://doi.org/10.3969/j.issn.1000-3428.2012.04.042In order to study the trust attack problem in complicated trust environment, the object-oriented trust attack graph model is put forward. In the model, the rule take, grant and pervade are used to describe trust level escalating, trust relation transiting, pervading and spreading resulting from utilization of vulnerabilities existing in attributes of trust entity objects, therefore a longer attack reachable distance can be reached. The model carries the attack complexity and harmfulness index which are used to determine the attack threat index, the vulnerability utilizing rules and trust relation embezzling rules are used to establish the trust relation transitive closure generating algorithm with polynomial time complexity, based on which a trust risk propagating algorithm is established. Through an experiment based on modeling real vulnerabilities for a system, the model is proofed to be correct.
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Computer Engineering. 2012, 38(04): 134-136. https://doi.org/10.3969/j.issn.1000-3428.2012.04.043In this paper, a watermark algorithm for vector map based on feature point is proposed. Before watermark bit is emedded, it is scrambled by Torus automorphic map. The curves are divided into a specified number of vertex set curves to define the feature point of the curves by the minimum angle of this curve. In the range of map precision allowing, by means of changing the feature point coordinates to manufacture the watermark image repeatedly embedded into the feature points. Experimental results show that this algorithm not only can assure a good map precision, but also has a good robustness under clipping and compressing attacks.
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Computer Engineering. 2012, 38(04): 137-139. https://doi.org/10.3969/j.issn.1000-3428.2012.04.044The scalar multiplication of Elliptic Curve Cryptosysytem(ECC) has big computational costs and memory consumption. Aiming at this problem, by means of the 2MOF representation of scalar, this paper uses the direct computation 2Q+P strategy, proposes a lower memory cost and some efficient left-to-right scalar multiplication algorithm. The analysis result indicates that this algorithm has lower computational cost and memory consumption, and can enhance the ECC’s efficiency in resource constrained environment.
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Computer Engineering. 2012, 38(04): 140-142. https://doi.org/10.3969/j.issn.1000-3428.2012.04.045Most of models are based on single random scanning, and worm has relatively fixed morphology. In view of this problem, this paper researches on permutation scanning technique, combines natural biological feeding and breeding rules, and proposes a mathematical model to characterize the dynamic propagation of polymorphic worms. The overall behavior of the worm is presented and the number of different type of worms in the process of propagation is analyzed by a series of inter-dependent equations. Experimental simulation result shows that this model can describe polymorphic worm propagation exactly.
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Computer Engineering. 2012, 38(04): 143-145. https://doi.org/10.3969/j.issn.1000-3428.2012.04.046Aiming at the problem that a huge mass of network data are real-time processed, this paper proposes application of support vector machine in intrusion detection. The number of samples for building detection model is decreased by applying data filtering strategy on the intrusion detection experiments. According to the importance measurement of each feature attribute, different weightings are given. It designs the feature weighted Support Vector Machine(SVM) algorithm. Experimental results demonstrate that the algorithm can effectively shorten building detection model time and improve detection accuracy. It can also lower false negative rate.
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Computer Engineering. 2012, 38(04): 146-148. https://doi.org/10.3969/j.issn.1000-3428.2012.04.047Aiming at moving object detection under the static background, this paper proposes a modified difference fusion algorithm. The proposed algorithm pre-processes the original image, combines with background difference and five frame difference, improves the method of automatically extracting background, it extracts moving regions in images by means of the dynamic threshold based on the adaptive background model, and gets the final moving objects by morphological filtering and connectivity detecting. Experimental result shows that the algorithm can extract moving objects more completely, with background more adaptable and real-time guaranteed.
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Computer Engineering. 2012, 38(04): 149-151. https://doi.org/10.3969/j.issn.1000-3428.2012.04.048For the problem of tracking long distance in-orbit non-cooperative point target, a synergy tracking algorithm of active/passive fusion system is given. Using Unscented Kalman Filter(UKF) algorithm based on passive sensor and intermittent-working mode of radar, the state information of non-cooperative target is established, using angle’s measurements provided by the optical camera and intermittent range’s measurements provided by the radar to estimate position and velocity of the target. The non-cooperative target’s state information can use as the initial orbit data for autonomy space operations. Simulation results indicate that the point target can be tracking consciously based on UKF algorithm when the state error and measurement noise are changing, and intermittent range information provided by radar can get better tracking accuracy.
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Computer Engineering. 2012, 38(04): 152-154. https://doi.org/10.3969/j.issn.1000-3428.2012.04.049A new method to construct multi-class classifier based on linear SVM is proposed in the paper. Its major procedures include: to form interval space polygon among point sets by subtracting operation of convex hulls, to extract polygon axes and then extend to construct the classification boundaries. The method can avoid problems like blind area in decision-making and imbalance data sets like traditional multi-class classification ways of One-Against-All(OAA) and One-Agianst-One(OAO) encounter. Simulation test results show that classification boundaries constructed by the method can realize the minimum risk and the maximum interval space among point sets, thus can be seen as an embodiment of the optimal classification lines of multi-class point sets.
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Computer Engineering. 2012, 38(04): 155-157. https://doi.org/10.3969/j.issn.1000-3428.2012.04.050The SIFT twice matching algorithm is proposed to get much more and reliable feature points in IRS-P5 remote sensing image matching. In order to get initial positioning points, uniqueness constraint and global geometric constraints are introduced to reduce matching error. micro-region images are got according to initial positioning points, and a new constraint-offset coordinate constraint is proposed together with the uniqueness constraint to complete the SIFT twice matching. Experimental results show that the matching number using the SIFT twice matching algorithm is 23.07 times of using SIFT directly with strict threshold value.
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Computer Engineering. 2012, 38(04): 158-160. https://doi.org/10.3969/j.issn.1000-3428.2012.04.051For the problem that Genetic Algorithm(GA) suffers from large iteration times and low efficiency in path-oriented test data generation, this paper proposes a Modified Genetic Algorithm(MGA), through analyzing the source code, structural information is gained and used to control the crossover and mutation point and range in order to make the genetic operation more accurate and purposeful. Experimental result shows that MGA has faster convergence speed and higher test data generation efficiency compared with traditional genetic algorithm.
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Computer Engineering. 2012, 38(04): 162-164. https://doi.org/10.3969/j.issn.1000-3428.2012.04.052Aiming at the problem of moving target tracking difficult under scale changes, an adaptive bandwidth algorithm is proposed by detecting the principal component variation of histogram. Considering the conspicuousness and similarity of target and background, a ratio relation is set up to select the feature which can differentiate the prospect target and background to its extent. The feature district amount is weighted by the discrimination. Target scale variation is determined by pixel amounts of principal component in histogram. A novel bandwidth criterion is defined for adjusting the tracking window adaptively. Experimental results show that the algorithm can detect the scale change of the target and make corresponding adaptation.
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Computer Engineering. 2012, 38(04): 165-167. https://doi.org/10.3969/j.issn.1000-3428.2012.04.053To detect text from complex background image, a text detection approach based on multi-structure element of morphology is proposed. It adopts a multi-structure element of morphology-based scheme to extract contrast edges. Then a coarse to fine text detection strategy is performed to detect text lines. Experimental results demonstrate that the proposed method can not only improve precision rate and recall rate but also save detection time.
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Computer Engineering. 2012, 38(04): 168-169. https://doi.org/10.3969/j.issn.1000-3428.2012.04.054According to monitor and control system in light of the existence of complex changes, this paper proposes a multi-camera object matching method based on color invariant. The human target is divided into head, torso and legs. Based on the Gaussian spectrum model, the color invariants of the edge and region are extracted in the derivative space and chromaticity color space respectively. Moment invariants descriptors for object matching are extracted by moment function, which are independent of the translation, rotation and scaling. Experimental results show that this method can effectively resist the complex light changes of the scene and inadequate characteristics under low-resolution conditions, etc., and achieve higher correct rate of object matching.
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Computer Engineering. 2012, 38(04): 170-173. https://doi.org/10.3969/j.issn.1000-3428.2012.04.055The traditional diagnosis method based on support vector machine lacks new type fault detection ability and expansibility. To solve this problem, a novel diagnosis method based on the combination of One-class SVM(OCSVM) and Multi-class SVM(MCSVM) is proposed. In this method, the OCSVM module is applied to the detection and preliminary classification of fault data, and the MCSVM module is used to improve the classification capability, which is a shortcoming of the OCSVM. Besides, the OCSVM algorithm is improved to perfect its detection and classification ability. Through an analog circuit fault diagnosis experiment, result shows the effectiveness of the improved OCSVM algorithm and the combined fault diagnosis method.
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Computer Engineering. 2012, 38(04): 174-175. https://doi.org/10.3969/j.issn.1000-3428.2012.04.056The block-based selective background update method exists weaknesses that it is unnatural between the block and the adjacent block and the anti-interference is weak. Thus, the block-based selective background update method is combined with the filtering method and the gradually correction method in order to refresh the background. The current frame and the previous one are divided into small blocks. According to the mean and variance of the current background, it is established that the foreground blocks, background blocks. The background blocks and the foreground blocks are separately updated. Test results demonstrate that when the method is applied to moving vehicle detection, the accuracy is improved by about nine percent and time efficiency also improved slightly.
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Computer Engineering. 2012, 38(04): 176-178. https://doi.org/10.3969/j.issn.1000-3428.2012.04.057With the same time duration, if Linear Frequency Modulation(LFM) signal possesses constant energy, its spectrum amplitude square is inversely proportional to the frequency modulation slope. Based on the theory, the frequency modulation slope and other parameters can be estimated by searching the parameter that is in accord with the largest amplitude square of demodulated signal. But the contradiction between high estimation precision and large computation amount exists in the algorithm. To solve this problem, the Particle Swarm Optimization(PSO) is introduced into the searching process. Searching area is divided more precisely to improve the parameter estimation precision. PSO is used to search the largest amplitude square to get the estimation results. Simulation experimental results validate that this algorithm consumes fewer computation amount but with better estimation precision.
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Computer Engineering. 2012, 38(04): 179-181. https://doi.org/10.3969/j.issn.1000-3428.2012.04.058In order to eliminate the effect of illumination on face recognition, an improved Self Quotient Image(SQI) algorithm is proposed. The algorithm performs nonlinear transform Gamma correction on image under various lighting conditions. Nonsubsampled Contourlet Transform (NSCT) is used for analysis with multiscale and multidirection, after that Wiener filter is applied to high frequency directional subbands for illumination invariant extraction. Experimental results on Yale B and CMU PIE databases show that the algorithm can effectively eliminate the effect of illumination on face recognition.
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Computer Engineering. 2012, 38(04): 182-184. https://doi.org/10.3969/j.issn.1000-3428.2012.04.059This paper presents a Parallel Cooperative Coevolutionary Differential Evolution(PCCDE) algorithm based on Cooperative Coevolutionary Differential Evolution(CCDE) and Bulk Synchronous Parallel(BSP) computing model. In this algorithm, Archive collaboration mechanism replaces the original mechanism in CCDE, the PCCDE uses the BSP model to implement the parallel computation. Simulation experimental results based on a set of widely used benchmark function show that the algorithm has superior calculation efficiency and quality.
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Computer Engineering. 2012, 38(04): 185-187. https://doi.org/10.3969/j.issn.1000-3428.2012.04.060An improved Variation Step Adaptive Glowworm Swarm Optimization(VSAGSO) algorithm is proposed to solve the problem of slow convergence and low precision and easy to fall into local optimization of the Glowworm Swarm Optimization(GSO) algorithm. It endows a big initial step to each glowworm. The step is decreased dynamically along with the increase of iteration so that the algorithm can get more precise solution in the end of the algorithm. Experimental results with six test function show convergence speed and precision is dramatically improved, which testifies that VSAGSO is a valid method to solve the global optimization problem.
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Computer Engineering. 2012, 38(04): 188-190. https://doi.org/10.3969/j.issn.1000-3428.2012.04.061Traditional wavelet transformation enhancement can not adjust the brightness of an image effectively. Aiming at this problem, this paper proposes a remote sensing image fuzzy enhancement algorithm based on Nonsubsampled Contourlet Transform(NSCT). The remote sensing images are transformed into the high-pass sub-band and low-pass sub-band by NSCT, and the threshold is set in the high-pass sub-band, the high-pass subband coefficients which is greater than the threshold is enhanced by linear enhancement, the high-pass subband coefficients which less than the threshold is set zero, the low-pass subband is enhanced by the fuzzy contrast enhancement. Experimental results show the effectiveness of the method in the improvement of entropy and the average.
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Computer Engineering. 2012, 38(04): 191-193. https://doi.org/10.3969/j.issn.1000-3428.2012.04.062The similarity criterion for image resizing is concluded, and a image resizing algorithm based on similarity criterion is proposed. Image resizing is implemented by Seam Carving algorithm, it removes the seams with the lowest gradient energy. The degree of image deformation and similarity can be judged using the similarity criterion. Before the degree of deformation reaches a threshold, the resizing method is changed to bidirectional similarity iteration optimization for residual amount. Experimental results show that, even though the amount of adjustment is large, the algorithm can preserve global visual effect.
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Computer Engineering. 2012, 38(04): 194-195. https://doi.org/10.3969/j.issn.1000-3428.2012.04.063To solve the image defects and image stretching generated by image scaling, a non-linear scaling algorithm based on Sobel operator and uniform interpolation is proposed in this paper. It uses gradient energy to distinguish the strong regions and the weak regions. Non-linear uniform interpolation scaling algorithm is used in weak regions, while it preserves those strong regions. Experimental results show that the algorithm can solve the problem of the main parts distortion generated by image scaling, and ensure a smooth transition between the region edges.
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Computer Engineering. 2012, 38(04): 196-198. https://doi.org/10.3969/j.issn.1000-3428.2012.04.064This paper proposes an image type fire detection algorithm based on fuzzy clustering. Flame color model is established. The pulsation frequency of fire-like regions is obtained by pixel motion accumulation method. The fire-like regions which are not connected but belong to the same flame are merged with supervisory and fuzzy clustering. A judgment is made by the movement characteristics of flame. Experimental results demonstrate that the algorithm has low misstatement rate and high efficiency, it can be used in most environments of fire detection.
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Computer Engineering. 2012, 38(04): 199-201. https://doi.org/10.3969/j.issn.1000-3428.2012.04.065Aiming at the problem of the over-smoothness and blurs the details, which are caused by exponential kernel function used in original non-local means algorithm, this paper proposes a cosine Gaussian kernel function based on exponential kernel function and combined with a cosine coefficient and Gaussian kernel. It is used in the weight-computing of the improved algorithm. Experimental results show the algorithm has a superior denoising performance than the original one, especially with detail information in the image, and PSNR can be improved by 1.6 dB at most.
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Computer Engineering. 2012, 38(04): 202-204. https://doi.org/10.3969/j.issn.1000-3428.2012.04.066Since the traditional entropy coding algorithm is hard to realize using hardware method and with high complexity, a Listless Zerotree image Coding(LZC) algorithm is proposed and implemented in Field Programmable Gate Array(FPGA) platform. The algorithm adopts the features from LZC and Set Partitioning in Hierarchical Trees(SPIHT), and adds the judgment for grandchildren nodes. With the improvement, the algorithm overcomes the high memory overhead and high complexity of SPIHT, and enhances the coding quality of LZC. For any size of images, the memory overhead for this coder implemented in FPGA is fixed, 1 536 bit, far less than that of SPIHT. The PSNR of decoded image is enhanced about 0.7 dB than LZC under the same compression bitrate. When the algorithm is implemented in Xilinx Virtex4 LX100, running at 100 MHz, it performs a frame rate of 20 f/s for 1 600×1 200×24 bit images with a compression ratio of 1/40.
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Computer Engineering. 2012, 38(04): 205-207. https://doi.org/10.3969/j.issn.1000-3428.2012.04.067In order to solve the high test cost and high test power, the study proposes a low cost test method. Using scan chain blocking technique, all sequence elements are divided into N scan sub-chains and only one scan sub-chain is active at a time during scan test. Not all elements need to be active in test. The division of sub-chain makes some sequence elements inactive in test model and make full use of scan elements. Experimental result demonstrates that the method can drastically reduce test application time with a low cost on hardware.
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Computer Engineering. 2012, 38(04): 208-211. https://doi.org/10.3969/j.issn.1000-3428.2012.04.068Based on Automotive Open System Architecture(AUTOSAR) specification architecture, by considering Stratified and sub-module, this paper designs Local Interconnect Network(LIN) bus, and describes the realization of LIN driver, LIN interface, protocol data unit router, communication, diagnose communication manager modules. Practice shows that the LIN bus realization based on AUTOSAR specification has better performance on migration, run speed and stability.
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Computer Engineering. 2012, 38(04): 212-214. https://doi.org/10.3969/j.issn.1000-3428.2012.04.069This paper designs and realizes an attitude stability augmentation control system for Mini Unmanned Helicopter(MUH), which is low-cost, independent, safe and reliable. It is applied to maintain the stability of MUH. The precision attitude values which are obtained by the estimate algorithm of gravitational complementary filter based on filtering switching are used as the feedback of this system. Multi-loop fuzzy PI cascade control is introduced because it does not require high accurate model. Experimental results show that the system has satisfactory performance on stability augmentation effect, and it is cheap for application.
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Computer Engineering. 2012, 38(04): 215-217. https://doi.org/10.3969/j.issn.1000-3428.2012.04.070Current BootLoader updating method is proposed for the debugging of one target board, but not for batch BootLoader updating. This paper proposes a new automatic updating method under the kernel. It extracts effective data from new BootLoader image files, saves them to the files with the suffix “.h”, uses a special Flash driver and above files to form a special kernel, and updates the special kernel into embedded system through peripheral removable storage device. After starting the kernel, BootLoader can automatically updated, so that batch BootLoader Automatic updating is finished.
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Computer Engineering. 2012, 38(04): 218-220. https://doi.org/10.3969/j.issn.1000-3428.2012.04.071This paper designs and implements a data management system for the Chang’e One. By using ArcSDE spatial database engine, ArcEngine component-based Geographic Information System(GIS) and .NET platform, it establishes the basic database of Chang’e One data and achieves the storage, query and distribution of a variety of raw data, maps of the results. And a three-dimensional virtual moon display platform and a management system for project document are developed. Application results show that the system can significantly improve security and efficiency of Chang’e One data management.
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Computer Engineering. 2012, 38(04): 221-223. https://doi.org/10.3969/j.issn.1000-3428.2012.04.072Aiming at the management problems of empty resources for dynamic reconfigurable system, this paper which based on empty resource management strategies of the maximum empty rectangle, proposes an improved scan line algorithm. The basic idea of the improved algorithm is to search for valid search width while searching for maximal empty rectangles. Experimental results indicate that compared with enhanced scan line algorithm, the improved algorithm effectively reduces the run-time overhead, and also, the cost of storage space by using one-dimensional array as an assist space.
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Computer Engineering. 2012, 38(04): 224-226. https://doi.org/10.3969/j.issn.1000-3428.2012.04.073From the enterprise management and the production links on Radio Frequency Identification(RFID) application requirements analysis, this paper researches RFID application mode in automobile manufacturing production line, constructs an automobile manufacturing line vertically distributed application model system framework based on RFID, and gives the system process of each function modules. Application results show that the model can solve the data loss and omissions in information collection and the low efficiency caused by artificial operation in the production process, and meet the requirements of real-time performance and accuracy in automotive manufacturing production line data information collection.
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Computer Engineering. 2012, 38(04): 227-229. https://doi.org/10.3969/j.issn.1000-3428.2012.04.074There are some defects such as poor real-time performance and difficulty in sharing information of locomotive on-line monitoring and diagnosis just by means of onboard failure diagnostic equipment not linked to Internet. This paper designs a locomotive remote monitoring and diagnosis system, which takes advantages of onboard data acquisition by embedded equipments, transmission over GPRS, failure expert diagnosis, Message Queue(MQ) technology and Brower/Server(B/S) client showcase. Application results show that the performance of the system is steady and reliable, and it is the essential technical support means for modern locomotive management and maintenance.
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Computer Engineering. 2012, 38(04): 230-232. https://doi.org/10.3969/j.issn.1000-3428.2012.04.075A distributed instrument system integration method based on eXtensible Markup Language Remote Procedure Call(XML RPC) is proposed. The system architecture of the C/S and B/S mixed mode is designed. The system software based on modularization and virtual instrument technology is designed and implemented, and its core is XML-RPC Server which consists of data access module, data management module, instrument management module and Web service interface module. Application results of the fermentation lab distributed instrumentation integration system show that the function of the lab equipment management and remote monitoring is effectively implemented, and the system operation is stable and reliable expandability.
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Computer Engineering. 2012, 38(04): 233-235. https://doi.org/10.3969/j.issn.1000-3428.2012.04.076There are serious drawbacks in information collection, distribution, storage, sharing and other sectors of traditional conference organization and management. To solve these problems, this paper analyzes the architecture and application of cloud services, virtualization technology and Duckling collaboration environment, puts a cloud service based solutions forward and researches and implements the conference services platform consisting of portal, virtualization background and conference sites. By creating a management site, providing one-click creating and flexible customizing conference site services. Application results demonstrate the effectiveness of the platform.
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Computer Engineering. 2012, 38(04): 236-238. https://doi.org/10.3969/j.issn.1000-3428.2012.04.077Aiming at the problems of fake and decrease of interspaces in Fuzzy Vault(FV) method, this paper proposes a voiceprint template protection method based on Chaff Matrix(CM). The CM is generated from raw feature and interweaved with raw template according to Orientation Matrix(OM), such that a cancelable template is designed to protect the voiceprint. Problems of fake and decrease of interspaces for Chaff Points(CPs) in FV are solved by the mixture on a thinner layer. Mathematical analysis explained the proposal doesn’t deteriorate the performance, for the invariability of the distance change between features. Experimental results show the validity of this method.
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Computer Engineering. 2012, 38(04): 239-240. https://doi.org/10.3969/j.issn.1000-3428.2012.04.078Using numerical integration formula, the two-dimensional Fredholm integral equation is discrete. By introducing the regularization method, the discredited integral equation is transformed into a posed problem of discrete and the numerical solution is obtained by Generalized Minimal Residual(GMRES) algorithm. In the numerical simulation, different methods are compared with regularization GMRES method. The results show that the regularization GMRES method have advantages for solving two-dimensional first kind Fredholm integral equation with high computing speed and high accuracy.
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Computer Engineering. 2012, 38(04): 241-244. https://doi.org/10.3969/j.issn.1000-3428.2012.04.079This paper presents a highly effective biological sequences alignment solution based on CPU-Graphic Processingr Unit(GPU) heterogeneous platform. The solution re-write Smith-Waterman(SW) algorithm in OpenCL platform, reorganizes the algorithm to adapt the GPU architecture and applies optimization of memory accessing latency and optimization of the memory deployment, fully utilizes GPU’s parallel processing capability, greatly improves the effectiveness of algorithm. Experimental result shows that the solution has 100 times performance increase than the serial algorithm in CPU.
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Computer Engineering. 2012, 38(04): 245-246. https://doi.org/10.3969/j.issn.1000-3428.2012.04.080The higher harmonic part of the speech signal is completely overwhelmed by the noise when Signal to Noise Ratio(SNR) is low. In response to this situation, a new algorithm is proposed. A quasi-periodic impulse signal is calculated based on the distorted signal processed by MMSE-LSA algorithm using a nonlinearity to regenerate harmonics. This artificial signal is then used to multiply the original enhanced signal, making the voice of the harmonic components to be prominent. Experimental results show that the algorithm is a good solution to the problem of Harmonic distortion better and is better than the traditional algorithm when improving the voice quality of high harmonics in low SNR.
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Computer Engineering. 2012, 38(04): 247-250. https://doi.org/10.3969/j.issn.1000-3428.2012.04.081Some redundant communications are introduced in parallel compilation of distributed-memory multi-computers to guarantee the consistency of program data. To solve this problem, this paper proposes an optimizing communications calculating algorithm. Based on dependence analysis and inter-procedural data-flow analysis, the algorithm can figure out more accurate communications data by traversing the Define-Use graph and eliminate the redundant communications generated by procedure calls. Experimental results show that using the results of the algorithm to generate MPI communications code can reduce the communications data and the speed-up ratio is close to manual MPI parallel program.
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Computer Engineering. 2012, 38(04): 251-253. https://doi.org/10.3969/j.issn.1000-3428.2012.04.082This paper makes a research on time management services of High Level Architecture(HLA). It proves optimistic time advance can solve lack of agility and a long emluator time of conservative time advance via analyzing and comparing of conservative time advance and optimistic time advance; And it introduces a generalized list storage structure. Its two-dimensional storage effectively resolves key storage and retraction technique of optimistic time advance. By testing and verification of the arithmetic, it proves that the arithmetic shortens the emluator time and heightens real-time of the simulation system.
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Computer Engineering. 2012, 38(04): 254-256. https://doi.org/10.3969/j.issn.1000-3428.2012.04.083A new method of vessel image enhancement is presented. Based on the multi-scale image analysis of vessel image, the vascular response function instead of gradient is applied to construct a vessel image diffusion coefficient. The constructed diffusion coefficient contains Forward and Backward(FAB) diffusion operation. While de-noising the image, it also sharpens the edge of the vessel image. Experiments on synthesis image and pulmonary image describe the performance of the method. This new method has a better result in image restoration than conventional diffusion methods.
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Computer Engineering. 2012, 38(04): 257-259. https://doi.org/10.3969/j.issn.1000-3428.2012.04.084Ultrasound inverse scattering imaging is studied by a method of spatial domain based on Singular Value Decomposition(SVD) and least squares solution. By converting the functional equation to algebraic equation with the approach of pulse basis and pointed-match, nonlinear problems are solved by iterative algorithm. The extent of ill-posedness can be determined by Picard theory and the equations can be solved by two kinds of methods of average handling and truncated singular value decomposition. Experimental results illustrate that solving ill-posed equations with appropriate regularization parameter can filter out the noise better and improve the quality of the reconstructed image and credibility, and also can reduce the amount of computation in the iterative process.
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Computer Engineering. 2012, 38(04): 260-262. https://doi.org/10.3969/j.issn.1000-3428.2012.04.085A novel lock scheme applied in distributed systems is proposed in order to fulfill the requirement of huge data throughput. The lock structure refines the granularity of data coverage and allows data sharing in the premise of data consistency while the lock localization algorithm decreases the time to look up lock objects. These methodologies are evaluated in terms of throughput benchmark and lock collision ratio, and simulation result demonstrates that with these optimizations the storage layer can provide high-performance random access to data retrieval requests from upper layer.
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Computer Engineering. 2012, 38(04): 263-265. https://doi.org/hzshi@ict.ac.cnFor 6LoWPAN protocol, this paper proposes a conformance test system based on TCL. The system consists User Interface(UI) control, test execution and device communication. Through the UI control, users can interact with the system and view results. The test execution module can provide test case execution, results analysis and so on. The device communication provides physical layer transceiver function. By using TCL script language to design test cases and extend commands, the system scalability is enhanced. The Contiki uIPv6 stack is tested and the results show that this system has the quality of expansibility, and can meet the 6LoWPAN protocol conformance test requirements.
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Computer Engineering. 2012, 38(04): 266-268. https://doi.org/10.3969/j.issn.1000-3428.2012.04.087This paper proposes a feature extraction algorithm for application layer protocol based on PrefixSpan algorithm. It adds the constraints about position to reduce the number of frequent sequence mode, and is combined with the practical situation of the feature extraction process to join constraint conditions. In the mining process, it reduces the number of projection database. In construction of the projection database, it removes the storage about the frequent items and the scanning of which sequence number is less than the minimum support degree in projection database. Experimental results show that compared with the original algorithm, the running time of this algorithm is shorter, and the extraction features have higher precision and lower false alarm rate.
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Computer Engineering. 2012, 38(04): 269-271. https://doi.org/10.3969/j.issn.1000-3428.2012.04.088To deal with the high power consumption and low speed of unfixed keywords matching based on Ternary Content Addressable Memory(TCAM), a low power consumption and high speed unfixed keywords matching algorithm is proposed. With the help of keyword classification data structure, keywords are stored in different blocks of TCAM and only the suspected keywords are put into TCAM to match. Therefore, the algorithm decreases the entries of TCAM and increases the average step length of data packets for each query cycle, so it can effectively reduce the power consumption of TCAM and improve the matching speed. Simulation result shows that the algorithm has lower power consumption and faster matching speed than traditional algorithms.
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Computer Engineering. 2012, 38(04): 272-274. https://doi.org/10.3969/j.issn.1000-3428.2012.04.089Based on the requirement of modeling a synthetic battlefield environment, a new ontology-based method is presented. To clearly lay out the relations between the conceptions, contexts are made from extracting the common views through the domain and views special views for some key processes. Relations are specialized in context, and context restriction ontology are constructed. Application result shows that the model has highly efficient retrieval and complex-relation-express ability.
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Computer Engineering. 2012, 38(04): 275-277. https://doi.org/10.3969/j.issn.1000-3428.2012.04.090In Least Slack First(LSF) schedule algorithm, when there are multiple tasks which have the same or similar task priority, too much context switch resulting “bump” phenomenon that will greatly increase the system overhead. Based on preemption threshold, combined with the characteristics of LSF algorithm, through the rational design of dynamic preemption threshold, this paper proposes an improved algorithm named DPTLSF. Simulation results show that the improved algorithm can effectively reduce the “bumps” from occurring and reduce the missed deadline percentage of task set.
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Computer Engineering. 2012, 38(04): 278-280. https://doi.org/10.3969/j.issn.1000-3428.2012.04.091In this paper, a novel symbol and clock synchronization scheme for Orthogonal Frequency Division Multiplexing(OFDM)-based China Mobile Multimedia Broadcasting(CMMB) is presented. Based on the fact that CMMB system is sensitive to the symbol and clock synchronization error, this paper gives a solution which uses the beacon of slot and Cycle Prefix(CP) to catch and tracing the window position. Clock error estimate is done with scatter pilot of OFDM symbol. The Root Mean Square Error(RMSE) of sampling time error is calculated as the standard of the scheme performance. Simulation results show the scheme is effective and feasible.
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Computer Engineering. 2012, 38(04): 281-283. https://doi.org/10.3969/j.issn.1000-3428.2012.04.092The basic principles of Advanced Propagation Model(APM) is described. Since the current electronic jamming model is not adequate for the influence of complex terrain and atmosphere, it is modified based on APM. This paper realizes the 3D detection range of ground radar on specific electronic jamming environment and specific terrain and atmospheric environment.
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Computer Engineering. 2012, 38(04): 284-286. https://doi.org/10.3969/j.issn.1000-3428.2012.04.093This paper proposes the calculating modes of earliest feasible time for real-time task schedule algorithm. It summarizes three convergence modes to obtain the earliest feasible time, including testing to the common multipy point, testing to the alignment deadline and testing to the smallest remaining utilization. It gives the simulation examples of each modes, and uses the time complexity to analysis the convergence modes above. The immediate insertion segment is determined on the immediate smooth insertion point. Simulation examples show that the convergence modes are right. In the operation processing, the three modes can realize the new task insertion at the earliest possible time.
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Computer Engineering. 2012, 38(04): 287-289. https://doi.org/10.3969/j.issn.1000-3428.2012.04.094This paper proposes the video smoke detection method based on space region growing and fuzzy inference. It analyses the fire smoke color characteristic and diffusion characteristics, and uses the three frames method and three-channel region growing segmentation algorithm to segment the smoke suspected area of the first frame image and the second frame image. It analyses the image light flow main direction of the suspected regions, and obtains the two images primary orientation angle ratio. This paper also uses the fuzzy logic intelligent analyzer to test whether the fire has happened. Experimental results show that the detection speed is faster, and can resist the interference.
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Computer Engineering. 2012, 38(04): 290-292. https://doi.org/10.3969/j.issn.1000-3428.2012.04.095After the earthquake, roads are subject to be blocked by landslides caused by aftershocks. To solve the problem of real-time monitoring of transport lifeline systems, the post-disaster road available monitoring system solution is put forward. Sensors selection and node configurations, node arrangement method, routing algorithm, multi-sensor information integrated algorithm, and image collection mode are discussed. Node arrangement is calculated by sensor coverage radius, expectations of the system coverage and system redundancy. In routing setup, the forwarding and maintenance algorithms are designed according to node arrangement and transmission characteristics. Experimental results show that the system can receive an alert and the image information in time when the event occurs.
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