15 November 2015, Volume 41 Issue 11
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Computer Engineering. 2015, 41(11): 1-7. https://doi.org/10.3969/j.issn.1000-3428.2015.11.001Task allocation is one of the key problems that need to be solved for design and implementation of multicore-based mixed-criticality system in automotive electronic system,and it needs to tradeoff among the schedulability,cost and resource efficiency.Aiming at solving this problem,this paper proposes a simulated annealing-based Criticality-aware Task Allocation(CTA) algorithm,which can realize the joint optimization of cost and resource efficiency by conforming to the constraint of system’s schedulability.The comparison experiment based on real-life automotive applications and simulated dataset verifies the effectiveness of the proposed CTA.
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Computer Engineering. 2015, 41(11): 8-12. https://doi.org/10.3969/j.issn.1000-3428.2015.11.002Aiming at the problem of long time delay and slow transmission speed of accident message publication method on highway,this paper proposes a Directional Single-hop Vehicular Broadcast(DSHVB) mechanism combining the application with Wireless Access scheme Vehicular Environments(WAVE).Each car node builds a car node list to record other cars driving in opposite direction,then accomplishes the directional accident message rebroadcast.It discusses the requirements to achieve reliable accident message forwarding and evaluates the performance of DSHVB using Veins.Experimental result shows that DSHVB has lower packet lost rate,higher quality of reliability and lower network load compared with flooding broadcast mechanism,and it meets the requirement of the fast broadcast of the accident message in highway scenario.
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Computer Engineering. 2015, 41(11): 13-17,23. https://doi.org/10.3969/j.issn.1000-3428.2015.11.003Considering the demand of low latency of intelligent vehicle access control system based on license plate recognition,a design for reducing the latency of system response performance from vehicle detection to lane release is proposed.This design mainly focuses on three aspects——pre-process in camera,image transmission and later-process in Industrial Personnel Computer(IPC).Using regional Auto Exposure(AE) in camera and asynchronous I/O image transmission to improve the performance of later license plate recognition,it realizes a kind of block transmission method combined with image region extraction while also optimizing image display in client-side of IPC,to improve the efficiency of the system’s each processing part.Experimental results show that from image acquisition to receiving,to processing and at last to show,this scheme can make system take about 136 ms while at the same time ensuring the accuracy of license plate recognition,which reaches the leading level in the field of vehicle access control system.
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Computer Engineering. 2015, 41(11): 18-23. https://doi.org/10.3969/j.issn.1000-3428.2015.11.004To resolve privacy-preserving problem in Vehicular Ad-hoc Network(VANET),a message authentication scheme is presented by using secret sharing technology.This scheme can protect the identity privacy information of vehicle by the threshold proxy re-signature algorithm.It turns a signature generated by On-board Unit(OBU) into a signature from a trusted certificate authority on the same message,so it can effectively eliminate the risk of tracking vehicle according to signature.The new scheme distributes the re-signature key into Road-side Unib(RSU).Therefore it can reduce the probability of successful decoding re-signature key and prevent RSU from misusing the re-signature rights.Authentication center can trace back to the message of the real vehicle released,and solve the problem of illegal vehicle recall.Analysis result shows that the new scheme has high security and low storage overhead compared with similar schemes.
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Computer Engineering. 2015, 41(11): 24-29,40. https://doi.org/10.3969/j.issn.1000-3428.2015.11.005In the Intelligent Road(iRoad) system,in order to meet the throughput requirement of packets with different priority,this paper presents an admission control protocol of dual-path routing based on priority.It analyzes the node available bandwidth based on priority and sends the paths which satisfies the requirement by data streaming to the final routing node.After receiving all the candidate paths,it selects the two best paths to meet the data streaming bandwidth requirement.When the data packet returns from final routing node,the local node uses its surrounding node available bandwidth prediction to do admission control to ensure preferential access of high-priority data streaming.Simulation results show that compared with the single-path-based admission control,the proposed algorithm has higher throughput,lower latency and jitter,which guarantees bandwidth demand for high-priority data flow.
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Computer Engineering. 2015, 41(11): 30-34,46. https://doi.org/10.3969/j.issn.1000-3428.2015.11.006As the popularity of portable wireless broadband router MiFi equipment,the interference of urban rail transit train becomes more and more serious,therefore it is necessary to analyze coexistence anti-interference between Communication-based Train Control(CBTC) system and MiFi device.In order to improve the performance of system,this paper proposes an improved Distributed Coordination Function(DCF) scheme based on adaptive section,dividing MiFi node number into several sections and setting different contention window value.It firstly analyses the distribution model of inside carriage MiFi devices and interference model between MiFi and CBTC system.Secondly,it sets partition interval and contention window value according to the characteristics of interference.Finally,it uses the simulation tool to analyze throughput,transmission delay and transmission failure rate of CBTC system,in order to compare the different data frame length performance of traditional DCF scheme and modified DCF scheme.Analysis results show that the new DCF model optimization scheme can effectively improve the CBTC train-ground communication performance under MiFi interference environment,and it can achieve a certain degree of the coexistence.
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Computer Engineering. 2015, 41(11): 35-40. https://doi.org/10.3969/j.issn.1000-3428.2015.11.007In order to deal with the incomplete information system with a variety of noise data,dominance information and other information,and acquire decision rules,the thought and method of the set pair theory,dominance relationship and variable precision rough set are used to construct a novel dominance variable precision rough set model based on set pair situation.With respect to the incomplete information system containing the missing attribute values,by utilizing the set pair analysis method,a set pair situation dominance relationship based on the threshold α connection degree is defined,and it is used to substitute the equivalence relationship of the variable precision rough set model,so that a novel variable precision rough set model based on the set pair situation is established,and its properties are researched.An example shows the feasibility and effectiveness of the proposed model.
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Computer Engineering. 2015, 41(11): 41-46. https://doi.org/10.3969/j.issn.1000-3428.2015.11.008With the explosive growth of the data on the Internet,the scale of the server cluster is rapidly expanding.How to carry out large-scale cluster monitoring and analysis becomes a difficult problem in the Internet industry.Therefore,this paper presents a new method for detection and analysis of the monitoring data according to the monitoring jittering data.It adopts pattern-based outlier detection method without setting a threshold,takes the eigenvalues,calculaties the outliers,and obtains the abnormal range and degrees.Experimental results show that the algorithm can extract data features for time sequence of jittering data,and has a higher precision and better applicability than the outlier detection algorithm based on mean-variance.
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Computer Engineering. 2015, 41(11): 47-51. https://doi.org/10.3969/j.issn.1000-3428.2015.11.009For the problems of long query time and poor data storage scalability of the existing crown word number management system,the cloud computing is applied to the storage and query of crown word number.The association form of storing information of crown word numbers is defined according to the money-adding process of bank ATM and the counting process of bank branches.In order to ensure the safety of crown word number,a Commutative Encryption Binary Search-Chord(CEBS-Chord) is proposed in this paper to realize index and data encryption.Theoretical analysis and experimental result show that the method can make full use of the virtual storage and virtual computing power of cloud computing platform,and it can meet the data transmission capacity and extension performance requirements of an crown word number management system.Compared with the current query methods,it has efficient query efficiency and high security.
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Computer Engineering. 2015, 41(11): 52-58. https://doi.org/10.3969/j.issn.1000-3428.2015.11.010Existing wait-free hash table algorithms do not take full advantage of the inherent parallelism of hash table,which results in the high redundancy and conflict between threads.In order to solve the problem,this paper proposes a fast wait-free hash table algorithm.It makes use of the freezable set to simplify the operations of hash table.And the Compare and Swap(CAS) primitive is applied to realize the wait-free of insertion,deletion and search operations.It improves the help mechanism based on the structure of hash table to realize the wait-free of hash buckets.In order to avoid the conflics between the operations on different buckets,the help is given only when the hash table extends.Experimental results show that the algorithm can reduce the conflict between thread operation,and improve the parallelism of help operation.When the percentage of lookup is 0,the data range is 0~256 and the thread number reaches 8,throughput of the proposed algorithm is 2.5 times than the existing wait-free hash table algorithm.
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Computer Engineering. 2015, 41(11): 59-66. https://doi.org/10.3969/j.issn.1000-3428.2015.11.011The current research on the recommendation system just considers the randomness too much but ignores the point of timeliness.This paper proposes a new multi-order Markov predicting recommendation system based on the traditional standard Markov model.The algorithm can make up for the deficiency of timeliness by using the new sliding time window mechanism.The algorithm can achieve the mission of accurate prediction about user’s browsing activity according to the study of the history data and the analysis of user’s browsing habits.Experimental results show that compared with the collaborative filtering scheme,the new proposed algorithm can provide the predicting recommendation efficiently and effectively judging by the user’s interest shift behavior.
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Computer Engineering. 2015, 41(11): 67-72,83. https://doi.org/10.3969/j.issn.1000-3428.2015.11.012The partition of complex network is useful to find the real community structure and help people research the real world,so this paper proposes a new algorithm of communities partition in network based on the local module degree and similarities.The algorithm calculates the similarities between the nodes in the network and aggregates the nodes which have the highest correlation.It aggregates the communities based on the local module degree and community similarity.Then the results is gotten which has the best local module degree.To verify the validity of the algorithm,this paper applies it in the real network and computer simulation network,and compares the algorithm with other algorithms.The result shows that the proposed algorithm has lower computational complexity and higher accuracy compared with NS1,CNM,LAP algorithms,etc..
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Computer Engineering. 2015, 41(11): 73-76,93. https://doi.org/10.3969/j.issn.1000-3428.2015.11.013In order to calculate the topological characteristics of large-scale complex networks faster,a distributed computing framework for analyzing large-scale complex networks is designed and implemented in this paper.It collects loose coupling computing nodes distributed in the local network or the Internet.By using a task queue,computing nodes can join or quit during computing at any time.By fully leveraging the loose coupling computing resources distributed in a network,the framework makes the speed of analyzing large-scale complex networks enhanced greatly.Based on this framework,the distributed computing of average length of the shortest paths and the efficiency of large-scale complex networks is implemented.Experimental results show that this framework can make full use of the idle computing resources in the network,and greatly improves the computing performance,on the premise of ensuring the correctness of computational results.
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Computer Engineering. 2015, 41(11): 77-83. https://doi.org/10.3969/j.issn.1000-3428.2015.11.014Thread Level Speculation(TLS) compiling can effectively improve the parallel efficiency.But the overheads,caused by the management of the speculative data and the failure of speculative thread’s rollback,decreases the improvement of the parallel performance.Aiming at the too big overhead of data management and thread rollback,the Hot Loops-TLS(HL-TLS) framework is proposed.HL-TLS marks the loops which can be efficiently paralleled as HL,using a more eager parallel way on HL to improve performance,while using conservative sequence way on non-HL to reduce the overheads.Experimental result shows that HL-TLS improves 20% performance.
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Computer Engineering. 2015, 41(11): 84-88. https://doi.org/10.3969/j.issn.1000-3428.2015.11.015In order to meet the requirements of real-time multiple tasks,Digital Signal Processor(DSP) should have the ability to switch applications dynamically in real time.Based on the analysis of the boot mode of DSP,and using large volume Nor Flash as caches of self-boot applications,this paper gives a solution of timely switch applications for multi-DSP system that employs CAN as control bus.Experimental result shows that the average boot time with cache is much less than that without cache,and under the condition of cache hit,applications can be switched in real time using this solution.
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Computer Engineering. 2015, 41(11): 89-93. https://doi.org/10.3969/j.issn.1000-3428.2015.11.016
Facing with the poor performance and high power consumption of microprocessor and inflexibility of ASIC in encryption and decryption computation,coarse-grain reconfigurable cryptographic algorithm processing architecture based on operating elements is proposed.This paper extracts atomic operations and instantiates them as processing elements.Operating elements are taken as reconfigurable gains,coupled with routing table and parameter table.Routing table is in charge of configuring interconnection network of operating elements while parameter table is responsible for configuring cryptographic algorithm parameters.By generating routing table and parameter table information according to different cryptographic algorithms,cryptographic accelerator is coarse-grain reconfigured to support various cryptographic algorithms.The circuit reaches clock frequency of 350 MHz using TSMC 0.13 μm cell library.Experimental results show that the architecture has both the advantages of microprocessor and ASIC and it flexibly supports various cryptographic algorithms.The required amount of information and resource consumption is less,and has better performance area ratio.
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Computer Engineering. 2015, 41(11): 94-99. https://doi.org/10.3969/j.issn.1000-3428.2015.11.017In order to verify the reliability of the software running on storage system formally,a formal model of NAND flash hardware is needed.According to an interface specification named ONFI that is recognized by many companies,a formal model for the semantics of NAND flash hardware is built in formal language.It includes the storage architecture of NAND flash defined by ONFI,the inner workflow of the commands,the command set of the NAND flash and several flash operations defined upon the model.The model is defined in a popular theorem proof assistant,Coq.This model can be used to define and verify the software based on NAND flash storage system.
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Computer Engineering. 2015, 41(11): 100-105. https://doi.org/10.3969/j.issn.1000-3428.2015.11.018Aiming at the problem that the low-priority interrupts have bad disturbance on high-priority tasks deadline in embedded real-time kernel,an improved interrupt management mechanism for μC/OS-Ⅲ is proposed.Priority assignment is based on the importance of interrupts which occurs during execution of the tasks.If interrupt is more important,its priority is higher than tasks priority,otherwise its priority is lower than task priority.Interrupt Service Routine(ISR) deals with the high-priority interrupts and interrupt service task deals with the low-priority interrupts.The result of the experiment and analysis of theory show that the improved interrupt management mechanism can reduce the response time of task and ensure the schedulability and predictability of the task.
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Computer Engineering. 2015, 41(11): 106-113. https://doi.org/10.3969/j.issn.1000-3428.2015.11.019With the development of open-source community,the number and complexity of available open-source software increases rapidly,then software systems becomes interdependent on account of the interaction between developers,dependence between components or modules and sharing of tools,and it forms open-source Software Ecosystem(SECO).This paper analyzes the composition,knowledge chain (Web) structure of SECO from the perspective of ecosystem,builds SECO model from three levels which includes software projects,similar themes and the entire open-source community.It analyzes four characteristics which includes openness,diversity,regulation and sustainability according to the main feature of ecosystems.It uses Sourceforge.net open-source community as a case study,indicates that the study of the open-source SECO is helpful to improve the survival ability and knowledge reuse by the effective strategies,and maintain its stability and health.
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Computer Engineering. 2015, 41(11): 114-119. https://doi.org/10.3969/j.issn.1000-3428.2015.11.020A multiple copies of a rack awareness placement strategy is adopted in the Hadoop Distributed File System(HDFS) to cope with the storage of very large scale data and improve the fault tolerance.However,the HDFS does not consider the difference of each node server,which can result in load imbalance of clusters.Meanwhile,HDFS chooses remote rack node to place replica randomly,which may lead to a long distance between nodes,so that the transmission of data between nodes consumes a lot of time.To solve the aforementioned problems,this paper proposes an improved strategy of HDFS replica placement based on SVM.It can find the best node for replica by considering the disk utilization of each node,the node’s hardware performance and network distance of nodes.Experimental results show that the proposed strategy effectively improves the load balancing in HDFS compared with the existing method used in HDFS system.
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Computer Engineering. 2015, 41(11): 120-125,130. https://doi.org/10.3969/j.issn.1000-3428.2015.11.021
Traditional multi-channel signal acquisition and storage system is facing a huge task of data collection,the lack of adequate transmission bandwidth and storage capacity in real-time.This paper proposes a Fibre Channel-small Computer System Interface(FC-SCSI) as the core of the real-time acquisition and storage solutions.It uses chain lookup table structure and dynamic flow control technology to improve the FC-SCSI software protocol storage efficiency,focusing on solving a large-capacity multi-channel synchronous stream data off the disk in real-time acquisition problems,and it realizes a large amount of data acquisition,real-time and reliable storage,portability and good performance integrated data processing storage systems.Experimental results show that under 2.125 Gb Fibre Channel(FC),reliable and stable storage speed is 186.6 MB/s,which is 94.7% of 2.125 Gb theoretical rate of FC,and the speed is enhanced by 11.7% compared with 167.1 MB/s of traditional FC-SCSI storage solutions.
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Computer Engineering. 2015, 41(11): 126-130. https://doi.org/10.3969/j.issn.1000-3428.2015.11.022In order to solve discrete optimization problem in Cognitive Rradio(CR) spectrum allocation and improve the allocation performance,this paper proposes a Discrete Quantum-behaved Particle Swarm Optimization(DQPSO) algorithm.It updates the particles with quantum computing theory and adjusts the rotation angle with wave function,and it has both advantages of fast convergence rate of Particle Swarm Optimization(PSO) algorithm and high precision of quantum computing.When applied in the problem of CR spectrum allocation,it can improve the performance of spectrum allocation effectively.This paper compares the performance of the proposed algorithm with the Genetic Algorithm(GA),Quantum-inspired Genetic Algorithm(QIGA),PSO algorithm and Color Sensitive Graph Coloring(CSGC) algorithm in different network benefit functions.Simulation results show that the proposed algorithm can search faster for the optimal solution,and it has better performance.
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Computer Engineering. 2015, 41(11): 131-134,141. https://doi.org/10.3969/j.issn.1000-3428.2015.11.023Researching the solution to the problem that how to measure the interference accurately and construct the topological structure with minimizing interference in the Wireless Sensor Network(WSN),it proposes topology control algorithm of threshold adjustment.It can minimize the interference heuristically in exponential node chain network model.In the network,each node collects useful information of its neighbor nodes,and at the same time,with the interference threshold as the objective function,it selects the link between the nodes,which are in line with current interference threshold and don’t make the current topology generate loop path.It constructs topology until the topology becomes connected graph,which can minimize the maximum interference among the nodes in the network.Simulation results show that,the new algorithm compared with the nearest algorithm on the exponential node chain network model of WSN,the interference generated topology control structure optimization effect is better,and can guarantee the connectivity of the network and more effectively prolong the lifecycle of the network.
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Computer Engineering. 2015, 41(11): 135-141. https://doi.org/10.3969/j.issn.1000-3428.2015.11.024
航空电子全双工交换式以太网(AFDX)对传输的数据流采用先到先服务(FCFS)调度策略,导致安全关键性数据的网络延迟较大,拥塞情况下的数据流延迟存在不确定性。为解决该问题,提出一种用于优化AFDX网络实时性的混合队列调度策略,综合FCFS调度策略、静态优先级队列调度策略和差额轮询调度策略的优点,通过网络演算分析数据流的延迟上界,理论验证硬实时数据流满足AFDX网络通信需求。仿真实验结果表明,混合队列调度策略不仅可以保证AFDX网络中安全关键性数据流的实时性,以及非安全关键性数据流的调度公平性,而且能有效隔离恶意数据流。
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Computer Engineering. 2015, 41(11): 142-146. https://doi.org/10.3969/j.issn.1000-3428.2015.11.025Unbalanced load of traditional Mobile Ad Hoc Network(MANET) results in bad consequences such as the increase of end-to-end delay,the decrease of delivery ratio and the death of nodes.In order to solve this problem,this paper proposes a modified load balancing routing algorithm based on Ad Hoc On-demand Distance Vector(AODV).The algorithm adopts the single path method and considers both current load and occurred load.Queue lens and energy consumption of the nodes are used to evaluate the loads.The modified algorithm pays attention to the importance of the bottleneck nodes.Simulation results show that compared with the traditional algorithm such as AODV,improvement of energy path,this algorithm has good adaptability in different load cases,and can provide more stable network performance.
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Computer Engineering. 2015, 41(11): 147-152. https://doi.org/10.3969/j.issn.1000-3428.2015.11.026Wireless Mesh Network(WMN) is a key technology of new generation wireless networks,and the structure of the backbone network is a decisive factor in achieving the connectivity and coverage of the network.Aiming at optimizing the deployment of WMN’s backbone network,an effective Mesh Router(MR) deployment algorithm for minimizing the number of MR under the premise of network connection and meeting the user’s demand of the bandwidth is proposed.Particle swarm algorithm is used to determine the location of the gateway.Then it adds nodes to the backbone network constantly until covers all requirements.Experimental results prove that the number of MR deployed of the proposed algorithm is less than NF-Greedy algorithm and ILSearch algorithm under uniform distribution and normal distribution,it can reduce the deployment cost effectively.
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Computer Engineering. 2015, 41(11): 153-159. https://doi.org/10.3969/j.issn.1000-3428.2015.11.027Aiming at network coding for single source multicast networks with fixed topology,this paper proposes a Linear Network Coding(LNC) algorithm based on subtree decomposition.It is composed of five steps:line graph transforming,subtree decomposition,edge disjoint path search,global coding vector assignment and local coding vector calculation.The algorithm starts with input of a Directed Acyclic Graph(DAG) with multicast property,and ends with output of global coding vectors and local coding vectors of each edge.Subtree decomposition is based on such a consideration that there is no need of coding within a subtree but only between subtrees.It is proved by theoretical analyses and experimental results show that,both network scale and complexity of path search and coding are greatly decreased through subtree decomposition,which greatly decreases running time of network coding algorithm.It can draw the conclusion that the proposed algorithm is an efficient algorithm to single source multicast networks.
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Computer Engineering. 2015, 41(11): 160-164,169. https://doi.org/10.3969/j.issn.1000-3428.2015.11.028Based on IEEE 802.15.4 signal model,by adopting the simplified frequency offset estimation algorithm,a novel Field Programmable Gate Array(FPGA) implementation scheme of frequency offset estimation algorithm is proposed in this paper,which saves hardware resources and is suitable for burst mode communication.The proposed scheme in the paper includes timing recovery,frequency offset estimation and frequency offset correction modules.By transforming parallel to serial calculation,the hardware resource occupation is reduced greatly.Using down-sample and dual-port RAM,the computing speed is improved effectively.By optimizing architecture,the FPGA implementation of frequency offset estimation and correction algorithm proposed in the paper is with large frequency offset estimation range,high frequency accuracy performance and low ratio in hardware resource utilization.Analysis results show the validity of it.
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Computer Engineering. 2015, 41(11): 165-169. https://doi.org/10.3969/j.issn.1000-3428.2015.11.029There exists a one-to-one correspondence between the set of access structures with n participants and that of hypergraphs with n vertices.This paper proposes a type of hypergraph,i.e.,r-uniform hypergraphs with complete k-partition.It proves that the type of hypergraph access structures is ideal by using vector space construction.The paper gives the number of this type of ideal hypergraph access structures using combinatorial mathematics,and gives all the ideal access structures with the number of participants (or vertices) 4,5,6 over a finite field F7 based on the r-uniform hypergraph with complete k-partition.Test results show that,compared with (r,n) threshold access structures and completek-partition graph access structures,the proposed ideal access structures are more vivid,and can be extensively applied in practice.
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Computer Engineering. 2015, 41(11): 170-179. https://doi.org/10.3969/j.issn.1000-3428.2015.11.030With extensive botnet arising as one of the major current network security threats,the automatic detection of botnet communication traffic is of high importance for Internet service providers and large corporation network monitoring.To solve the problem,this paper proposes a novel approach for botnet detection,a real-time botnet detection algorithm,where netflow related data is correlated as the host netflow graph structure and the host access chain structure,and a feature extraction method is leveraged for exacting implicit characteristics.Meanwhile,this paper establishes BotScanner detection system,which is a real-time steam processing engine.It trains BotScanner system on the four representative bot families and evaluates BotScanner on simulated network traffic and real-world network traffic.Experimental results show that BotScanner is able to detect bots in network traffic without the need of deep packet inspection,while still achieving high detection rates with very few false positives.When the netflow data from the core switch is very large,BotScanner is able to detect botnet in real-time by the efficient algorithm.It proves the feasibility of applying BotScanner system to botnet detection.
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Computer Engineering. 2015, 41(11): 180-185,201. https://doi.org/10.3969/j.issn.1000-3428.2015.11.031
km-anonymity can resist background knowledge attacks of m-length subjectory.However,the existing anonymized algorithms select the minimum support point,not the minimum distortion point to generalize.Therefore,with increasing of m,the distortion of the trajectory tends to be larger.To address the problem,this paper proposes two kinds of anonymized algorithms:one is the minimum distortion greedy anonymized algorithm,the other is the minimum distortion greedy anonymized algorithm with apriori principles.These two algorithms both take consideration of the effect of the generalizing distortion,and choose the minimum distortion point to generalize,which can cause less distortion.It also proposes a method to measure the anonymous trajectory utility.It analyses the data availability and algorithm efficiency.Experimental results show that the proposed algorithms can generate anonymous trajectory with higher trajectory utility than existing anonymized algorithms.
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Computer Engineering. 2015, 41(11): 186-189,206. https://doi.org/10.3969/j.issn.1000-3428.2015.11.032Vehicular Ad hoc Network(VANET) faces serious security threats about privacy preservation,because of its high privacy sensitivity of drivers,huge scale of vehicle number,variable node velocity,and openness.Aiming at these problems,this paper proposes an efficient and accountable privacy-preserving protocol of VANET.In this protocol,the Road-side Unit(RSU) and On-board Unit(OBU) form a temporary group which is the default team leader.The vehicles in the RSU’s communication range can join the group if necessary.The RSU verifies the group member’s validity and maintains the configuration for the group.As a communication centrum,RSU can reprocess the message from its group member,and then transfer it to others.For the accountability,RSU inserts a corresponding trace entry into the trace log about the message.The disputed message’s real signer can be traced out with the cooperation of the RSU.Analysis result shows that,compared with GSB,ECPP,DCS and WDG protocol,this protocol has lower complexity and load overhead,and it has accountability.
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Computer Engineering. 2015, 41(11): 190-193. https://doi.org/10.3969/j.issn.1000-3428.2015.11.033Ranking the search results and returning the most matched documents is an important and basic function for searchable encryption technique.In order to support such function in asymmetric searchable encryption,this paper proposes a method to transform the asymmetric structure to symmetric structure.Combining with the preserving-order encryption,searching in the mixed encrypted documents is realized.In comparison with prior works that only support symmetric encryption,the algorithm supports asymmetric encryption.Experimental results show that the new algorithm is efficient and practical.
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Computer Engineering. 2015, 41(11): 194-201. https://doi.org/10.3969/j.issn.1000-3428.2015.11.034Remote Supervised Method(ReSuMe) adjusts the synaptic weights according to the time difference between output and input spiking during neuron runtime.Whether for the theoretical basis or the practical application,ReSuMe method is a kind of relatively excellent supervised learning method for spiking neurons. But when the desired output spriking sequence is long,the learning accuracy of ReSuMe method is relatively low. In order to discusse ReSuMe method more detailed and improve its learning performance,two factors that affect the learning performance of ReSuMe method are studied. The first factor is the offline or online learning model,the other is the choice of the input spiking considered when adjusting the synaptic weights. Online learning accuracy is generally higher than offline learning, but the different of learning precision is big with different parameters or other settings. And a new learning strategy is proposed for the second factor to improve the ReSuMe method, it considers input and output spiking sequence when calculates weight adjustment,avoids the overlap interference of input spiking when increases and decreases weights. Experimental results show that the new strategy can greatly improve the learning accuracy of ReSuMe method under different experiment settings. So it has a strong ability to solve practical problems.
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Computer Engineering. 2015, 41(11): 202-206. https://doi.org/10.3969/j.issn.1000-3428.2015.11.035In order to report the service failure of the host or data interrupt in the virtual environment caused by undue resource allocation,this paper proposes a fault prediction model for virtual host.This model uses logs of the virtual host to mining the fuzzy association rules of fault predictions.Aiming at large error about rule matching problem in fault predictions caused by the edge data in cluster region,the model presents the threshold iterative algorithm based on the rules for solving the log data preprocessing coefficient,improving the rule matching rate.Experimental result shows that the prediction model can predict fault before the actual service fails,with an accuracy above 85%.
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Computer Engineering. 2015, 41(11): 207-212. https://doi.org/10.3969/j.issn.1000-3428.2015.11.036Automatically extracting Protein-protein Interaction(PPI) from biomedical literature is a significant task in text mining.Considering the choice of features and the selection of classifier is of great importance for Protein-protein Interaction Extraction(PPIE) task,this paper proposes a method to combine various features and multiple classifiers.Fifteen lexical,syntactic and semantic features,three kinds of classifiers and the standard ten-fold document level cross-validation evaluation method are used to evaluate on the five public PPI corpuses,and results show that the method achieves the preferable F-score(63.7%) and AUC-score(87.8%) on the AIMed corpus which is on the top of the PPI extraction task,and it has better extraction performance.
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Computer Engineering. 2015, 41(11): 213-217. https://doi.org/10.3969/j.issn.1000-3428.2015.11.037Hybrid structure of deep network which achieves low classification error rate when meeting noisy and limited training data is presented since many real world pictures are under noise.Proper sparse regularization algorithm is applied to auto-encoders,which are set on the lower and higher layers and can distinguish background noise more effectively.Middle layer is proposed on the basis of the undirected Gaussian-Bernoulli Restricted Boltzmann Machine(GRBM) to a better abstract representation.Hybrid structure of deep network uses a regression layer on the top for fine-tuning and classification.Experimental results show that hybrid structure of deep network can achieve better performance under noisy background regardless of number of training samples.
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Computer Engineering. 2015, 41(11): 218-223,231. https://doi.org/10.3969/j.issn.1000-3428.2015.11.038多文种融合文字书写教学系统的教学资源具有多语源的特点,但存在知识点数据类型多、计算结构复杂等不足。为此,依据不同文种文字书写的异性与共性规律,提出基于文字书写过程计算的知识点自动生成方法。将多文种的笔画、笔画关系、部件关系等计算元按 共享、分类,给出各类计算元编码空间的计算方法,定义面向各文种通用的文字书写过程计算模型,设计并实现计算模型中各计算元编码的自动生成算法。实验结果表明,该方法能准确识别各种知识要素,笔画及各类关系的识别正确率达到98.3%,与人工编码相比,录入速率提 高15%,冗码率降低23%。
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Computer Engineering. 2015, 41(11): 224-231. https://doi.org/10.3969/j.issn.1000-3428.2015.11.039A fast stereo matching algorithm based on dynamic programming is proposed to improve the efficiency of stereo matching to meet the real-time requirement and reduce the streaking phenomenon in a disparity map to increase matching accuracy.In this algorithm,the fast adaptive weight aggregation is firstly used to aggregate raw matching costs.Secondly,the stage of dynamic programming for computation of disparities is accelerated by two dimensional order tables.Finally,a disparity postprocessing method based on oriented filters is employed to reduce the streaking phenomenon in a disparity map.Experimental results show that the proposed algorithm can improve the efficiency of stereo matching and the matching accuracy.It can be applied in real time matching system.
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Computer Engineering. 2015, 41(11): 232-238. https://doi.org/10.3969/j.issn.1000-3428.2015.11.040Traditional address localization methods based on rules are difficult to accurately identify the background and target address block in envelope with cluster background due to its complicated background,not fixed position,etc.This paper presents an address block localization method based on vision saliency.It uses the Binarized Normed Gradient(BING) method to identify the candidate regions,whose local saliency maps are similar with the training blocks.Region covariance descriptors are adopted to nonlinerly fuse various low-level features,for example,pixel location,intensity,gradient and texture features.Support Vector Machine(SVM) are applied to classify the cadidate regions into address or non-address block.In order to further pinpoint the address block’s text region in envelopes,it uses the image signature to compute sparsity saliency and Gaussian filter to smooth the saliency map.Experimental results show that this method can accurately locate the target address block with the accuracy of 85.8%,which is 33.5% higher than methods based on conditional random fields.
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Computer Engineering. 2015, 41(11): 239-244,252. https://doi.org/10.3969/j.issn.1000-3428.2015.11.041In order to support the aircraft intelligent maintenance efficiently,an airframe damage region division method based on multi-dimension gray entropy and improved Chaotic Differential Evolution(CDE) algorithm is proposed.By analyzing the principle of gray entropy threshold division,it is defined as the adaptive function of airframe damage region division method.Then,Logistic chaos model is introduced,and cyclic mapping is used to mapping the range of chaotic variables into optimization variables,the searching optimization process of the chaotic differential evolution algorithm is improved,and the ergodicity of the method is enhanced.Airframe damage region division experiments are performed by different types of damage image.Experimental results show that divided damage region is clear and effective,and error rate is low.Compared with gray entropy exhaustion method,running speed of the proposed method is raised obviously.The problems of differential evolution algorithm such as stagnation of convergence in the middle-later period of the iteration,uneven distribution of sample points are solved effectively.It can be much better to meet the requirement of aircraft intelligent maintenance.
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Computer Engineering. 2015, 41(11): 245-252. https://doi.org/10.3969/j.issn.1000-3428.2015.11.042Taking the single feature and the major classification algorithms into consideration,an image classification algorithm based on fusion of multi-feature for Deep Belief Network(DBN) is proposed to classify the nature images.The features about color,texture,shape are extracted and the characteristic weight matrix is formed.Then the characteristic matrix is normalized.The samples are trained and classified using the DBN with four levels which is constructed.The proposed method has been evaluated on the Corel dataset by train weight,and the result shows that the average classification accuracy is 85.1% by the proposed algorithm,which is higher then single feature algorithm and other mainstream algorithms.
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Computer Engineering. 2015, 41(11): 253-256. https://doi.org/10.3969/j.issn.1000-3428.2015.11.043Structure Similarity(SSIM) is an important indicator of measuring the similarity of two images,but there still remain some deficiencies when assessing badly blurred images.In this paper,a new method using image texture combines with SSIM,which takes the importance of the texture information to images and human eye perception structure into account.The algorithm combines texture features in Discrete Cosine Transform(DCT) domain with SSIM to acquire the Texture Structure Similarity(TSSIM).Experimental results for Pearson correlation coefficient is 0.893 42,and the Spearman rank correlation coefficient is 0.925 07,which show that the proposed method works better in the aspect of subjective visual impression than SSIM.
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Computer Engineering. 2015, 41(11): 257-262. https://doi.org/10.3969/j.issn.1000-3428.2015.11.044As the issue of low recognition precision of general Salient Object Detection(SOD) method that is vulnerable to the impact of the background area,method of SOD using constrained Simplified Swarm Optimization(SSO) and multi-visual feature is proposed.Three visual features such as multi-scale contrast,center-surround histogram and color spatial distribution are obtained from the given image.Constrained Simplified Swarm Optimization(CSSO) is used to determine an optimal weight vector with combining these features to obtain saliency map to distinguish a salient object.A salient target is extracted from the salient map in the image background.In order to effectively suppress the background in the image area,a simple fitness function is defined to highlight the clear target containing boundary.Simulation is on MARA SOD database using quantitative and qualitative methods for evaluation.Experimental results show that the recognition precision and the recall rate of the proposed method are higher than that of the fuzzy clustering method,low-rank matrix recovery method and sparse reconstruction method.
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Computer Engineering. 2015, 41(11): 263-266. https://doi.org/10.3969/j.issn.1000-3428.2015.11.045Lots of existing image watermark algorithms based on Contourlet transformation cannot resist brightness and contrast attack.In order to solve the problem,a blind robust quantization-based watermark algorithm against brightness and contrast is presented.The original image is transformed by Contourlet transformation and gets low frequency band and high frequency sub-bands,and the low frequency band is split into non-overlapping blocks.Each block is decomposed with Singular Value Decomposition(SVD) and a bit of watermark is embedded into the Component of S through odd-even quantization.The inverse Contourlet transformation and SVD are applied to obtain the carried image with the watermark.At the detection end,revision for resistance against brightness and contrast is used to the attacked watermarked image and a watermark is blindly extracted through odd-even judgment.Experimental results show that the proposed algorithm has good transparency for the embedded watermark and it is strongly robust against brightness and contrast attack.
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Computer Engineering. 2015, 41(11): 267-272. https://doi.org/10.3969/j.issn.1000-3428.2015.11.046As the performance of multi-target tracking based on Marked Point Process(MPP) is poor,a hybrid multi-target detection and tracking is proposed.The improved frame difference method is used to determine the preliminary of the target.Local background weighting is applied to identify further and mark the targets.The consistency of the dynamic model is considered.Energy is used to constraint target dynamics,long-term tracking and target similarity and mutual exclusion.Reversible jump Markov chain Monte Carlo is applied to optimize the nonconvex energy function.Some image sequences are added with different levels of noise.Experimental results show that in the image sequences with Gaussian noise,compared with other tracking algorithms,the similarities of the proposed algorithm’s detection and tracking are highest.In addition,the precision and recall in satellite image sequences and self-capture videos are also highest.The overall performance of the proposed algorithm is better.
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Computer Engineering. 2015, 41(11): 273-279,286. https://doi.org/10.3969/j.issn.1000-3428.2015.11.047With the improvement of cable transmission speed, higher and higher demands of measurement precision of cable pitch are proposed.For this reason, this paper designs a cable pitch measurement algorithm based on image detection technique.It splits foreground and background of the cable image and uses the distributed situation of foreground pixels in feature space to achieve the Fuzzy C-mean(FCM) clustering. It obtains feasible solutions of fitting equation and the distance between adjacent feasible solutions by using specific pixel fill fitting,image thinning and data fitting based on edge detection.It converts image pitch value to an actual pitch value by the image scale.Experimental results show that the algorithm can calculate the cable pitch quickly and efficiently,and the absolute error of cable pitch between the proposed algorithm and laser ranging algorithm is about 0.75%.It has a high degree of measurement precision.
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Computer Engineering. 2015, 41(11): 280-286. https://doi.org/10.3969/j.issn.1000-3428.2015.11.048When processing an image with the blurred background and target,image segmenting effect by maximum between cluster variance 1D-Otsu and 2D-Otsu is not good.A method for image segmentation based on Gray-level Spatial Correlation(GLSC) maximum between-cluster variance is proposed.The proposed algorithm uses the gray value of the pixels and their similarity with neighboring pixels in gray value to build a histogram which is called GLSC histogram.Then threshold value is obtained by calculating GLSC histogram maximum between-class variance.Integrogram is introduced in order to make the time complexity reduced from original O((N2×L)2) to O(N2×L).Comparing the proposed algorithm with 1D-Otsu,2D-Otsu and GLSC entropy algorithm for segmenting 5 different real images,the proposed algorithm shows better robustness.
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Computer Engineering. 2015, 41(11): 287-293,298. https://doi.org/10.3969/j.issn.1000-3428.2015.11.049Aiming at the existing problems in the computation of planar offset curves such as adaptability and error control,this paper proposes a new algorithm for generating the approximation offset of planar curves based on the Progressive-iteration Approximation(PIA).This algorithm generates line segments approximating the exact offset curve by adaptive sampling on the progenitor curve with tangent vector angle that transfers the problem of approximating curve to that of curve approximating line segments.It reduces the number of sample point as possible at the premise of reflecting the shape feature of the progenitor curve.Then the algorithm selects the characteristic points on the offset curve as the dominant points,and interpolates the dominant points by using the PIA to generate a B-spline curve approximating the line segments.The B-spline curve can approximate the offset curve under the given error by utilizing the method of error control proposed in this paper and the locality of PIA.Experimental result shows that this algorithm is of intuition and easy implementation,which can be used directly for arbitrary planar parameter curve and function curve.It can increase the operating efficiency of the algorithm without solving a global linear equation system.
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Computer Engineering. 2015, 41(11): 294-298. https://doi.org/10.3969/j.issn.1000-3428.2015.11.050Smoothed l0 norm(SL0) algorithm utilizes a sequence of smoothed Gaussian function with parameter to approximate the l0 norm,which can be used efficiently for the compressive sensing reconstruction.Block-sparse signal is a typical sparse signal whose non-zero coefficients occur in a few blocks.This paper proposes a block sparse signal reconstruction based on improved SL0 algorithm with respect to the block sparse signals.The smoothed Gaussian function is substituted by inverse tangent function,and the convergence equality is further improved by optimizing the decreasing factor.Simulation results show that,compared with Block Smoothed l0 Norm(BSL0) algorithm,Smoothed l0 Norm(SL0) algorithm,and Orthogonal Matching Pursuit(OMP) algorithm,the proposed method has better robustness and higher Signal to Noise Ratio(SNR).
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Computer Engineering. 2015, 41(11): 299-302,307. https://doi.org/10.3969/j.issn.1000-3428.2015.11.051Correct prosodic boundary prediction is crucial for the quality of synthesized speech.This paper presents the prosodic hierarchy of Uyghur language which belongs to agglutinative language.A two-layer bottom-up hierarchical approach based on Conditional Random Field(CRF) is used for predicting prosodic word and prosodic phrase boundaries.Morphological features are considered useful for prosodic boundary prediction and added into the feature sets.In order to further enhance the accuracy of prosodic boundary prediction at punctuation sites,CRF based prosodic boundary determination method is used and integrated with bottom-up hierarchical approach.Consequently,the best prosodic boundary prediction performance is achieved by large and repeated experiment of different feature sets and different models.Experimental results show that the proposed method obviously improves the recall rate prediction of the prosodic boundary.
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Computer Engineering. 2015, 41(11): 303-307. https://doi.org/10.3969/j.issn.1000-3428.2015.11.052The acquisition process of gene expression dataset mixed with noise easily,the noise can interfere with data expression correctly which will affect their further analysis and research.The Empirical Mode Decomposition(EMD) denoising of using median-calculation to estimate noise standard deviations that exists some drawbacks and affects the denoising effectiveness.Under the EMD,the fractional Gaussian noise(fGn) model can provide more accurate estimation way of noise standard deviations,denoising on this model can reduce white and colored noise,which will enhance the denoising effectiveness.So a denoising scheme based on fGn is proposed on the basis of median-calculation EMD denoising and done the denoising analysis on colon cancer gene expression dataset.Experimental results show that,the values of signal-to-noise,noise rejection ratio,t-test,etc.in advanced method have a certain superiority compared with median-calculation EMD denoising,which can be used as an reference means of denoising to the gene expression dataset.
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Computer Engineering. 2015, 41(11): 308-313. https://doi.org/10.3969/j.issn.1000-3428.2015.11.053To address the problem that mobile target is difficult to track in complex indoor environment and the particle diversity is losing after the resampling step,a Radio Frequency Identification(RFID) indoor tracking algorithm is proposed.It treats Received Signal Strength Indication(RSSI) sample values received by readers as observation parameter directly to establish a nonlinear state space model,while a new adaptive partial systematic resampling algorithm with Markov Chain Monte Carlo(MCMC) move step is presented.The new algorithm resamples after classifying the particles with a measure function and the MCMC move step is joined after resampling steps to improve the diversity of particles.Applying this proposed algorithm to simulate the nonlinear single variable static model and nonlinear tracking model mentioned above,and compared with other resampling algorithms,the results show that the new algorithm has a better filtering performance and tracking accuracy.
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Computer Engineering. 2015, 41(11): 314-321. https://doi.org/10.3969/j.issn.1000-3428.2015.11.054In order to improve the accuracy and time efficiency of the tamper video detecting algorithm,a new algorithm based on texture spectrum is proposed.The algorithm is implemented in three stages:firstly,the spectrum image sequences of the video clip is computed;then,the correlation coefficient and abnormality degree of texture spectrum image sequences are defined and calculated;finally,the forgery places are detected by threshold approach.Experimental results show that the proposed method can effectively localize the tamped position of the frame duplication,insertion,deletion tampers.The average consumption of time is 0.4 s per frame in resolution 352×288.The precision and recall are all exceeding 94%.
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