15 March 2016, Volume 42 Issue 3
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Computer Engineering. 2016, 42(3): 1-6. https://doi.org/10.3969/j.issn.1000-3428.2016.03.001
Aiming at the problem of multi-hop data transmission among mobile vehicles in Vehicular Ad Hoc Network(VANET),combining the moving features of vehicle in cities,this paper proposes a Data Forwarding mechanism based on Distributed Learning(DFDL) by improving the existing BubbleRap routing mechanisms.Based on the “store-carry-and forward” message transmission mode,DFDL determines the vehicles’ community tags by using the time interval and frequency of enwunter,and calculates the centrality of nodes by the mobile entropy of vehicle movement.During data forwarding,DFDL selects appropriate relay nodes for data packet messages by comprehensively judging the community tags and centrality of nodes.This mechanism achieves multi-hop message forwarding among moving vehicles in long distance.Experimental results show that,for moving vehicles in cities,DFDL significantly improves the message delivery ratio and the average delivery delay performance than the BubbleRap routing mechanism.
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Computer Engineering. 2016, 42(3): 7-12. https://doi.org/10.3969/j.issn.1000-3428.2016.03.002
For the problem of network congestion caused by using table driven routing protocol in urban traffic,this paper proposes a modified Zone Routing Protocol(ZRP).It takes bus’s characteristics of constant speed and fixed rate into consideration,builds cluster by the rule that considering bus node as the head node of the cluster and ordinary car node as the intra-node of the cluster.On the basis,it establishes bus backbone network,and uses ZRP to promote the communication among the vehicle nodes by using active routing mode and on-demand routing mode.Simulation results show,compared with Ad Hoc On-demand Distance Vector Routing(AODV) protocol and Destination-sequenced Distance Vector(DSDV) protocol,the routing protocol has great improvement in transmission delay,packet loss rate and routing overhead.
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Computer Engineering. 2016, 42(3): 13-17. https://doi.org/10.3969/j.issn.1000-3428.2016.03.003
Communication links are easily affected by speed and irregular location distribution due to high-speed movement of cars in Vehicular Ad hoc Network(VANET).A routing optimization scheme based on link reliability is proposed after analyzing the characteristic of car driving.Links reliability optimization is realized by dividing stable communication distance,calculating available connecting time and the handling mechanism of max multiple value of links.Experimental results show that,compared with AODV and other schemes,this scheme has a better performance on link reliability,data transport efficiency and the disconnecting number of link.
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Computer Engineering. 2016, 42(3): 18-21,28. https://doi.org/10.3969/j.issn.1000-3428.2016.03.004
Vehicle identity is the vehicle’s exclusive user legitimate identification stored in trusted centre,which is directly related to the vehicle user’s information,so that its anonymous authentication reflects the protection of user privacy.Based on a certificateless signature scheme,this paper proposes an anonymous authentication protocol without the management of certificate or the problem of key escrow.The security and performance of the proposed protocol are analyzed.Result shows that the protocol has higher efficiency than the certificate-based authentication protocol and the identity-based authentication protocol.It is anonymous,undeniable,mutually authenticated,privacy preserving and anti-attack.
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Computer Engineering. 2016, 42(3): 22-28. https://doi.org/10.3969/j.issn.1000-3428.2016.03.005
In order to study the influence of node movement direction and movement speed on the dynamism of Vehicular Ad Hoc Network(VANET),a link dynamic analysis model is established by limiting the path width and node propagation range in the actual VANET environment.The theoretical expression of link duration and its Cumulative Distribution Function(CDF) are derived.The theoretical results are verified by the simulation experiment,and the results show that the theoretical analysis results are in good agreement with the simulation data,and node movement speed,road width and node transmission range have a certain impact on the results,however the node transmission range on the VANET link duration is relatively large.
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Computer Engineering. 2016, 42(3): 29-33,39. https://doi.org/10.3969/j.issn.1000-3428.2016.03.006
In order to solve the problem that multi-dimensional non-functional properties are not taken into consideration during the design of Controller Area Network(CAN),such as real-time,security and reliability,this paper proposes an integration optimization model.The scalability and bandwidth utilization ratio are used as the optimization objectives of the model.Under the premise of meeting the requirement of real-time,reliability and safety,by means of increasing the weight of scalability and bandwidth utilization,the unified optimization of both is realized.Then different objectives are normalized to get the balance optimization within the range.On this basis,integrating signal packaging ideas,it presents the multi-dimensional non-functional properties integration optimization algorithm in CAN system based on Simulated Annealing(SA).Experimental results on real signal set and simulated signal set show that compared with the situation of integration optimization without considering multi-dimensional non-functional attributes,this algorithm can obtain higher objective optimization rate.
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Computer Engineering. 2016, 42(3): 34-40,46. https://doi.org/10.3969/j.issn.1000-3428.2016.03.010
Hadoop Distributed File System(HDFS) has excellent features like high fault-tolerant,scalable,low-cost,which is widely used in the present large data storage and analysis scenarios.But for the mass small files storage,HDFS exposes defects like high memory consumption and high latency access.For “Hefei City Cloud” system’s “upload once download many” feature,this paper proposes an optimization scheme based on small files’ attributes.According to the correlation between files,it defines the priorities.For files smaller than 5 MB,it first merges them by priority level and then uploads,to generate an index record.Combining radomization thought,it uses two level caching policy to improve access efficiency.Meanwhile,the system regularly checks the access log,according to the habits of users,adjusting the prefetching factor dynamically.Experimental results show that the proposed scheme can effectively improve the efficiency of small files access,reduce memory usage of NameNodes and DataNodes.It can significantly improve the interaction of the system for storing and accessing mass small files.
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Computer Engineering. 2016, 42(3): 41-46. https://doi.org/10.3969/j.issn.1000-3428.2016.03.012
This paper carries out the collaborative optimization of wagon-flow connection in technical stations and train operation adjustment in sections,realizes the transportation region’s line and flow cooperation by adjustment of trains on the way,and obtains better transportation production index.According to the relationship between wagon-flow connection in technical stations and the train operation adjustment,this paper proposes the concept of requiring wagons and builds the correlation between the arrival and departure trains during the research period from the angle of wagon-flow connection in technical stations.It takes the technical station’s expected arrival time as the operation adjustment target.There are few relative researches which take the wagon connecting optimization as the trains’ operation adjustment target.Analysis results show that the traditional research of line and flow cooperation mainly studies how to organize the flow in stations according to the lines,seldom researches how to adjust the lines on the network to match the flow in stations.This paper converts the one-way coordination into two-way coordination,and lays a foundation for further study on the collaborative optimization of wagon-flow organization and train operation adjustment in technical stations.
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Computer Engineering. 2016, 42(3): 47-52. https://doi.org/10.3969/j.issn.1000-3428.2016.03.017
According to the characteristics of BWDSP100 processor’s architecture,this paper presents several practical ways to improve the performance of digital signal transformation functions in Digital Signal Processor(DSP) function library,including using special assembly instructions,instruction-level reordering,zero-overhead looping instruction,Instruction-level Parallelism(ILP),software vectorization and pipelining.It realizes parallel optimization version in library based on the original order version.Experimental results show that,in four-macro parallel mode,all digital signal transformation functions can achieve 9x speedup,90% functions can achieve 10x speedup,and 11.12x speedup is achieved on average.
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Computer Engineering. 2016, 42(3): 53-60,68. https://doi.org/10.3969/j.issn.1000-3428.2016.03.016
TreeMatch algorithm is widely considered to be an effective Twig query algorithm.According to the disadvantage of TreeMatch algorithm’s repeated analysis on Twig pattern,partial evaluation technology in the field of compilation is applied,and a Twig query optimization scheme is proposed.Analysis on Twig pattern is completed ahead of scheduling through partial evaluation,generating instruction sequences for query to replace the original query program,and a special execution engine of query machine is provided,thus eliminating repeated calculation and optimizing the eXtensible Markup Language(XML) tree pattern query.Experimental results show that the proposed optimization scheme can effectively improve the execution efficiency of XML query in different Twig patterns.
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Computer Engineering. 2016, 42(3): 61-68. https://doi.org/10.3969/j.issn.1000-3428.2016.03.009
Job scheduling is an important factor influencing the performance of the Hadoop platform.The job scheduling based on the Simple Genetic Algorithm(SGA) has disadvantages that the evolution generation is long and the rate of convergence is slow.In addition,there is redundant computation in encoding and decoding as well as the process of genetic operation,which increases the total scheduling time.To solve the problems,this paper proposes a job scheduling algorithm based on CHC genetic algorithm.It uses the double objective function and the method of keeping the optimal solution to decrease the total scheduling time and the average execution time of the job,so it speeds up the covergence rate of the optimal solution.Experimental results shows that CHC has great improvementthat in the scheduling efficiency and the utilization rate compared with SGA.
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Computer Engineering. 2016, 42(3): 69-73,79. https://doi.org/10.3969/j.issn.1000-3428.2016.03.011
In order to effectively improve the prediction accuracy,this paper proposes a prediction method by analyzing the time series of relevant water level station,which is based on Autoregressive Distributed Lag(ADL) model,combining with the control factors of water flow and the other relevant site location.According to the characteristics of the time series of water level,an investigation is conducted from the model determining,modeling and implementing.The model is applied in the one-day ahead prediction of water level in Shashi water level station with several other commonly used time series forecasting models,and in the tests on the expansibility of prediction length.Experimental results show that the proposed model can well fit the trend,and achieve high prediction accuracy.
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Computer Engineering. 2016, 42(3): 74-79. https://doi.org/10.3969/j.issn.1000-3428.2016.03.007
Aiming at the complexity and redundancy of the evaluation index in the aquatic product safety assessment system,a new attribute reduction algorithm based on attribute unimportance is proposed.The algorithm uses the method of fusing the positive region and the information,defines the formula of attribute unimportance,and calculates the attribute unimportance of the samples which excepts the core attribute in order to reduce the search space.Experimental validation and analysis show that the attribute reduction effect of the algorithm is better than that of heuristic information attribute reduction.It can be used to reduce the assessment index in the aquatic product safety assessment system.
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Computer Engineering. 2016, 42(3): 80-83,88. https://doi.org/10.3969/j.issn.1000-3428.2016.03.008
With the rapid growth of network applications,the efficiency of traditional network traffic classification method based on ports and payloads is reduced greatly.Meanwhile,most traffic flow classification methods do not consider the correlation among the flows at present.Aiming at these problems,this paper proposes an improved network traffic Bayes classification method based on correlation information.Flow correlation information is modeled by Bag of Flow(BoF),and a method of nonparametric kernel density estimation applied to the Bayes classifier is introduced.The Bayes classification method is improved by performing the nonparametric kernel density estimation to various types of distribution functions.Experimental results show that this improved method can achieve higher classification accuracy compared with KNB and BoF-NB method.
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Computer Engineering. 2016, 42(3): 84-88. https://doi.org/10.3969/j.issn.1000-3428.2016.03.013
Existing test case reduction methods basically only take the size and the error detection rate of the optimization set into consideration,rarely paying attention to the test efficiency,so that the test of the opitimization set takes long,and the test cost is high.For this problem,this paper proposes a triple target search algorithm.It details the double target priority model based on the coverage and the test cost of the test case,refines each target’s quantitative method,then calculates the priority of each test case according to the model,uses the priority as the initial pheromone value in the improved ant colony algorithm for ergodic optimization,at last regards the error detection rate as the impact factor for the ant to pick the next node,and formulates the pheromone update rule to find the optimal solution as soon as possible.Experimental results show that compared with the greedy algorithm,basic ant colony algorithm and other algorithms,this algorithm can get a smaller optimization test suite,higher error detection rate.
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Computer Engineering. 2016, 42(3): 89-93. https://doi.org/10.3969/j.issn.1000-3428.2016.03.014
Testing and simulation are main technologies used to ensure the proper running of distribution feeder automation system.But they both refer to the low-level details of electrical equipment so that the computing resources are scattered,affecting the verification efficiency and the coverage of system paths.For this problem,a new verification method for distribution feeder automation system is proposed.The formal model of the feeder automation algorithm is built by abstracting the actions and features of electrical equipment.Then,the automatic model checking technology is used to verify the correctness of the algorithm.Test results show that,this verification method focuses computing resources on the verification of action logic of algorithm by separating the low-level details.So it has higher verification efficiency and covers all system paths,and it can also reduce the cost of bug fixing.
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Computer Engineering. 2016, 42(3): 94-97. https://doi.org/10.3969/j.issn.1000-3428.2016.03.015
The control tasks without sequential properties in the control software of mechatronic system can not be clearly presented by monogamous statecharts model.According to the characteristics of tasks in real-time multi-task control system,tasks without sequential properties are introduced in the model and the statecharts model of the control software is expended.The expended model is comprised of sequential control tasks,asynchronous concurrency control tasks,cycle control tasks and global real-time control tasks.To implement the expanded model,each task in the model is encapsulated in function block.Function blocks are scheduled by their enable bits.Application result shows that the proposed modeling extension and implementation method reduce coupling between mission control modules and complex of control software,improve the real-time of mechatronic control system through task scheduling,and in a example control system,the cycle time of the software develop by introducing modeling and implementation method is 1 ms~2 ms while the cycle time of previous software is 2 ms~3 ms.
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Computer Engineering. 2016, 42(3): 98-102,110. https://doi.org/10.3969/j.issn.1000-3428.2016.03.018
In the application of multi-robot system communication,the Ad Hoc On-demand Distance Vector(AODV) routing protocol in Ad Hoc network has some disadvantages such as the low packet delivery ratio,the high communication delay when the network topology changes quickly.This paper proposes an optimized AODV routing protocol AODVH.In AODVH routing protocol,the source node chooses route based on routing cost which is the weighted calculation of the hop count and node speed,at the same time the source node maintains a backup route.Every time it makes sure that the optimal is the main route and the suboptimal is the backup route.This paper analyses the result of simulations based on NS2.According to the simulations,the optimized protocol can improve the packet delivery ratio,and reduce the normalized overhead and average end-to-end delay.
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Computer Engineering. 2016, 42(3): 103-110. https://doi.org/10.3969/j.issn.1000-3428.2016.03.019
Traffic matrix is an important input for traffic engineering in hybrid Software Defined Network(SDN),but it is difficult to be directly measured.Existing estimation methods are mainly for the traditional IP networks,not fully applicable to hybrid SDN.In order to solve this problem,this paper proposes an Adaptive multi-Elman Neural Network Algorithm(AMElman) based on Origin-Destination(OD) flow clustering.By clustering OD flows according to the time change pattern,the single high-dimensional training sample can be decomposed into several multiple low-dimensional training samples,and each of the low-dimensional samples’ key characteristics can be strengthened to train the corresponding Elman neural network and construct the multi-Elman model.At the same time,using the feature that part of the hybrid SDN OD flows can be measured accurately and constantly,the estimation algorithm’s parameter can be dynamically adjusted based on change of network status in the estimation process.Experimental results show that this algorithm has higher estimation accuracy and better adaptability than General Tomogravity(GT) algorithm.
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Computer Engineering. 2016, 42(3): 111-115,120. https://doi.org/10.3969/j.issn.1000-3428.2016.03.020
Aeronautical Ad Hoc Network(AANET) allows nodes to communicate though single hop or multi-hip way,and it does not need to rely on the ground control center.It provides flexible network architecture for aeronautical communication.Aiming at this characteristic,this paper proposes an Evolutionary Self-organizing Time Division Multiple Access(ESTDMA) protocol for AANET.It aims to optimize the slot utilization of the existing STDMA protocol while preserving the advantages of it.By introducing a contention-based secondary slot allocation strategy,ESTDMA enables nodes to contend to utilize the free and collision slots in the frame.Meanwhile,an analytical model is developed to obtain the optimal contention probability for the nodes to contend for the slots.The accuracy of analytical model is validated through the comparison of the simulation results and the analytical results.Also,the simulation results in EXata network show that the proposed protocol can effectively improve the slot utilization of the STDMA protocol,thus improving the performance dramatically.
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Deployment Optimization of Integrated Network Node Based on Improved Artificial Bee Colony AlgorithmComputer Engineering. 2016, 42(3): 116-120. https://doi.org/10.3969/j.issn.1000-3428.2016.03.021
In order to improve the deployment efficiency of the integrated network nodes,an integrated network node location deployment algorithm is proposed based on the improved Artificial Bee Colony(ABC) algorithm when considering the cross coverage of nodes and interference between nodes.In the deployment algorithm,the deployment problem of network nodes which is based on the signal model is converted into the optimization problem of ensuring high coverage and low interference of nodes,and the improved ABC algorithm is used to optimize the objective function of node deployment.Simulation results show that the algorithm can not only find the best position for global deployment quickly and accurately,but also effectively reduce interference between the integrated network nodes under the premise of the largest coverage of Radio Frequency Identification(RFID) tags.
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Computer Engineering. 2016, 42(3): 121-124. https://doi.org/10.3969/j.issn.1000-3428.2016.03.022
Because of the high initial value sensitivity,complexity and strong correlation,the chaotic sequence is suitable to be used as spread spectrum sequence.But in practice,the chaotic sequences should be optimized selection.In order to achieve more chaotic sequences with excellent performance,an improved optimized selection algorithm is proposed.In this algorithm,the relevant parameters about balance and correlation of Gold sequence are taken as the threshold value,and it combines with diagonal movement algorithm and logical operation algorithm to realize optimized selection.The simulation results on multi-user spread spectrum communication system show that more chaotic spread spectrum sequences can be achieved by the algorithm than diagonal movement algorithm and logical operation algorithm,and these sequences have better correlation and higher capability of multiple access interference than that of Gold sequence.
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Computer Engineering. 2016, 42(3): 125-129. https://doi.org/10.3969/j.issn.1000-3428.2016.03.023
In Cognitive Radio Network(CRN),wideband spectrum detection based on Compressive Sensing(CS) only focuses on spectral efficiency.Energy efficiency is hardly considered in spectrum detection phase,which results in larger energy consumption with the improvement of spectrum detection performance.Hence,CRN wideband spectrum detection method based on Bayesian Compressive Sensing(BCS) sparse reconstruction with the guarantee of energy efficiency is proposed.Sensing energy analytical formula is derived and the corresponding energy consumption model is constructed.The minimization of sensing energy consumption can be achieved via the change of sample numbers in BCS measurement matrix,with the constraint conditions of wideband compressive spectrum detection probability and BCS reconstruction Mean Square Error(MSE) thresholds.Simulation result indicates that,when false alarm probability is 0.04,the detection probability of the proposed method outperforms sensing-energy tradeoff approach obviously in fewer sample numbers scenario.Moreover,when reconstruction MSE is lower than 15 dB,compared with Orthogonal Matching Pursuit(OMP) method,reconstruction energy consumption based on BCS can be reduced obviously.
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Computer Engineering. 2016, 42(3): 130-137. https://doi.org/10.3969/j.issn.1000-3428.2016.03.024
Previous researches mainly focus on balancing physical server utilization based on Virtual Machine(VM) migration and ignore network status and the communication dependencies among VMs,which may result in network congestion and affect the system performance.To solve the above problems,this paper designs a server load balancing strategy in data center based on OpenFlow network.OpenFlow controller has the ability of managing the whole network according to switch and flow level aggregate statistics collected from the data plane.The load balancing strategy proposed in this paper takes account of both server-side constraints and network resources required by communications among VMs based on topology and the available link bandwidth,as well as the migration cost.It selects a destination server with least amount of system and network cost for a migrated VM.Experimental rusult shows that this strategy can reduce the possibility of network congestion and ensure the quality of service for the application on the VM.
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Computer Engineering. 2016, 42(3): 138-142. https://doi.org/10.3969/j.issn.1000-3428.2016.03.025
In ZigBee network,the routing path is single,causing the energy consumption is not uniform,and network energy cannot be effectively used.The ZigBee routing algorithm for load balance is proposed by sending directed RREQ packet,and the network storm is reduced.Based on the node and its neighbor nodes’ energy,the average energy of the whole network,consumption of the routing path,and the balance cost are set.The optimal path is selected and network dynamic routing is constructed,balancing the network load.At the same time,a cluster tree protection mechanism is established to prolong the network lifetime.Through the simulation,optimization algorithm in node deaths,energy consumption are reduced,and survival time is increased,compared with classic ZigBee routing algorithm and improved algorithm.
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Computer Engineering. 2016, 42(3): 143-147. https://doi.org/10.3969/j.issn.1000-3428.2016.03.026
This paper analyzes the characteristics of ambient energy harvesting,and proposes a Wireless Sensor Network(WSN) clustering routing algorithm based on ambient energy harvesting prediction.In cluster head selection stage,it predicts the coming ambient energy,nodes with higher prediction value and more residual energy are more likely to act as cluster heads.Other nodes join the cluster according to the communication cost.Simulation results show that compared with the existing algorithms,the proposed algorithm can improve network energy balance and improve the average energy level of network nodes.
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Computer Engineering. 2016, 42(3): 148-155. https://doi.org/10.3969/j.issn.1000-3428.2016.03.027
General dynamically updatable multi-secret sharing schemes require the participation of a trusted center,and the problems of adding or deleting several members or secrets simultaneously are not solved.A new multi-secret sharing scheme without trusted center is proposed in this paper.Shared multiple random secrets do not need to be pre-determined.They are jointly generated by all participants.At each updating stage,participants construct the update polynomials by one-way hash chains to update shares periodically.Everyone can verify the validity of the distributed information based on zero-knowledge proof.New members can get shadow secrets with the help of existing members and the times of updating polynomials can be altered,so the problems of simultaneously adding or deleting several member and serects are solved.The analysis result indicates that the scheme has higer security compared with existing schemes.
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Computer Engineering. 2016, 42(3): 156-160. https://doi.org/10.3969/j.issn.1000-3428.2016.03.028
Certificateless public key cryptography solves the key escrow problem of identity-based cryptography.In common with identity-based cryptography,certificateless public key cryptography does not rely on certificate.Therefor,this paper references from the thought of certificateless public key cryptography,a class of provably secure certificateless signature schemes based on Elliptic Curve Discrete Logarithm Problem(ECDLP) without pairing is proposed,which includes eight kind of signature schemes.The proposed schemes are proved provably secure in random oracle model.The analysis result shows that the proposed schemes can resist two types of super adversary and existential forgery attack,accordingly the proposed schemes have a higher security.The signing algorithm of the optimal scheme only needs one scalar multiplication,and the validation algorithm of the optimal scheme only needs two scalar multiplication.The optimal scheme is more computationally efficient than the existing schemes.
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Computer Engineering. 2016, 42(3): 161-164. https://doi.org/10.3969/j.issn.1000-3428.2016.03.029
Linear complexity is an important index for measuring the randomness properties of the sequences.Based on the theory of generalized cyclotomic,a new class of quaternary balanced generalized cyclotomic sequences with period 2pq over finite field F4 is constructed.Using the theory of polynomial roots over finite field,linear complexity is determined by examining the common root of generating polynomial of the sequences and polynomial x2pq－1 over the algebra closure of F4.The results show that the new sequence has high linear complexity.It is a good sequence from the viewpoint of cryptography.
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Computer Engineering. 2016, 42(3): 165-171,176. https://doi.org/10.3969/j.issn.1000-3428.2016.03.030
Existed privacy security studies focus on privacy and security issues of data,user identity and single service request,and for the privacy leakage problem of multiple cloud service requests causing by multidimensional environment,such as factors logical association and timing series disclosures,there is no complete solution.For such problems,this paper proposes a method for measuring the importance of privacy information for multiple cloud service requests,then makes risk assessment based on D-S evidence theory for this scenario,and finally combines with the improved noise generation and obfuscation strategy to build an effective protection framework for the privacy of multiple cloud service requests.Experimental result shows that the proposed method can ensure the security of multiple cloud service requests without significantly increasing the overhead.
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Computer Engineering. 2016, 42(3): 172-176. https://doi.org/10.3969/j.issn.1000-3428.2016.03.031
With the extensive application of Radio Frequency Identification(RFID),the contradiction between its security and computation is serious.On this background,the security defects and cost of the main RFID secure authentication protocols are analyzed.On this basis,a new authentication protocol is promoted with higher security and lower cost.Its security is verified via the strand space model,which proves that the mutual authentication of reader and tag can be realized safety and reliability.The analysis results show that the protocol is resistible to attacks such as spoofing attack,eavesdrop attack,replay attack,type flaw attack,tracking and so on,and also provides perfect forward secrecy,which has a lower computation,and is suitable for low-cost RFID system.
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Computer Engineering. 2016, 42(3): 177-181. https://doi.org/10.3969/j.issn.1000-3428.2016.03.032
In order to solve the poor dynamic adaptability to the node’s behaviors in current P2P trust models and deal with the variety of malicious attacks in the network,a new P2P dynamic trust model is proposed.Several parameters are introduced in computing trust worthiness of peers,including capacity evaluation,similarity,feedback credibility,service expectation,recent trust,historical trust and so on.Together,referring to the idea of congestion control in computer network,additive increase/multiplicative decrease,a mechanism of rewards and punishments is introduced in the calculation of feedback credibility.These parameters are adjusted in time to reflect the dynamics of the trust environment using time attenuation factor and time decay function.The trust evaluation is able to simulate the real trust relationship and has better adaptability to the dynamics of trust.Theoretical analysis and simulation show that the model has advantages in modeling dynamic trust relationship.It is highly effective in suppression of malicious attacks.
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Computer Engineering. 2016, 42(3): 182-187. https://doi.org/10.3969/j.issn.1000-3428.2016.03.033
In order to detect and stop malicious stream that is disguised as legitimate application stream,a security framework based on virtual machine introspection technique is proposed.It uses hardware events combined with virtual machine introspection and memory analysis,authorizes outgoing application stream only if the data is truly based on user intent,and detects the behavior of malware software running application protocols or injecting legal procedure to prevent malicious data stream.The viability of this framework is demonstrated by implementing it along with support for email client application Outlook Express,proving its ability on security monitoring for PC to ensure the legitimacy of the network stream.
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Computer Engineering. 2016, 42(3): 188-191,197. https://doi.org/10.3969/j.issn.1000-3428.2016.03.034
Aiming at the problem that the gene feature selection based on discrete Particle Swarm Optimization(PSO) algorithm is easy to fall into local optimal solution,a combined optimization algorithm based on discrete PSO and neighborhood reduction is proposed.Neighborhood reduction can effectively excavate gene data.The optimization function of the discrete PSO algorithm is constructed based on the dependence of the conditional subset of decision attributes.According to the optimization function value,it guides the particle to search the optimal gene feature subset,so as to solve the problem of local optimum.Experimental results show that the algorithm can obtain higher classification accuracy compared with hybrid optimization algorithm based on PSO and genetic algorithm,optimized neighborhood rough set,etc.
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Computer Engineering. 2016, 42(3): 192-197. https://doi.org/10.3969/j.issn.1000-3428.2016.03.035
In Max-min Ant System(MMAS) algorithm,initial pheromone distributes well,it can not reach global search,which is easy to stop and falls into local optima.Therefore an improved MMAS algorithm is proposed based on Tent chaotic mapping to enhance the capability of escaping from local optima.This method generates a group of candidates to guide the distribution of pheromone by exploiting ergodic property of chaos.When the searching stagnation is appeared,a chaotic disturbance method is utilized to obtain a better solution.Results among different ant colony optimization algorithm on large-scale Traveling Salesman Problem(TSP) show that the improved algorithm has higher success rate and faster convergence rate for global optimization.
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Computer Engineering. 2016, 42(3): 198-203,207. https://doi.org/10.3969/j.issn.1000-3428.2016.03.036
Thangka image is different from landscape image or other art image.It has rich colors,irregular forms,non-representational texture,plentiful content,complex composition,and overflowing with miniscule and elaborate details.According to the special characteristic,multi-feature based religious ritual implement recognition method in Thangka image is proposed.The Hu moments and Local Binary Pattern(LBP) are combined to describe the feature of object image effectively,and a new algorithm Distance Density k Nearest Neighbor(DDkNN) classification algorithm is given,the main idea of this algorithm is that the class of test sample is related to the neighbor training samples,and the closer the distances,the higher the relevance becomes.Experimental results show that,compared with traditional kNN,BP neural network and Integrate BP neural network,this algorithm is simple and effective to recognize for religious ritual implements in Thangka image.
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Computer Engineering. 2016, 42(3): 204-207. https://doi.org/10.3969/j.issn.1000-3428.2016.03.037
Aiming at the subcarrier resource allocation problem of cognitive radio network based on Orthogonal Frequency Division Multiplexing(OFDM),and considering the NP feature of the problem,an algorithm based on Artificial Physics Optimization(APO) is presented.The model of the problem and the solving process of the algorithm are given.Polyandry discrete encoding,population initialization method,and particle force equation are designed for problem solving.Experimental results show that the proposed algorithm can reduce the total transmitting power required by the system,improving subcarrier allocation.
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Computer Engineering. 2016, 42(3): 208-213. https://doi.org/10.3969/j.issn.1000-3428.2016.03.038
Considering the term relationship and the characteristics of Particle Swarm Optimization(PSO),a hot topic detection method based on Discrete Particle Swarm Optimization(DPSO) is presented.The term mutual information and the intra/inter information are constructed to update the traditional text representation model.DPSO is adopted to detect hot topic which not only simplifies the clustering process but also takes clustering evaluation criteria as fitness function to get optimal solution of clustering results.Experimental results demonstrate that this algorithm can detect hot topics from huge number of microblogs accurately and quickly,and it has high accuracy and efficiency of hot topic discovering.
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Computer Engineering. 2016, 42(3): 214-219. https://doi.org/10.3969/j.issn.1000-3428.2016.03.039
Economic Load Dispatch(ELD) is one of the typical optimization problems in the operation and scheduling of power systems,which plays an important role in improving the economy and reliability of power systems.However,valve-point effects and some constrains such as the transporting ability and system stability change it into a non-smooth and non-convex optimization problem which challenges the traditional optimization techniques in finding the optimal solution in reasonable time.By integrating cuckoo search with the penalty function constrains addressing mechanism,this paper presents a new constrained cuckoo algorithm to solve the economic load dispatch.To illustrate the effectiveness and robustness of the proposed algorithm,3 IEEE typical cases are selected and examined by this novel method,results show that,compared with some ELD solution techniques reported in the literature,the proposed algorithm has good searching ability to find the global optima,and has good accuracy and convergence characteristics,which provides a new way to solve ELD problem in practice.
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Computer Engineering. 2016, 42(3): 220-225. https://doi.org/10.3969/j.issn.1000-3428.2016.03.040
This paper researches filtering method to identify objects with fuzzy bordary based on cascading and integrated attribute morphology filtering.It focuses on principle of morphological attribute filtering such as the area,area brightness contrast,shape,topological height and descendants,and analyzes theirs filtering adaption.It proposes an counting statistics mode by the node attributes of a maximum tree.It concretely probes the connected region topological distribution node attribute description and purrning methods according to theirs gray level.It is suitable for recognizing overlapped objects and object segmentation with different types of fuzzy boundary,and implements efficient and disciplinary filtering for complex boundary image by flexible structural elements.The experimental result shows that the proposed method clears away area of disinterest background interferences in a fuzzy image efficiently compared with previous object recognition methods,and it promotes the recognition accuracy rate for various cell images.
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Computer Engineering. 2016, 42(3): 232-235. https://doi.org/10.3969/j.issn.1000-3428.2016.03.042
Aiming at the problem of image classification with a complex background,this paper proposes a new image algorithm based on Neighborhood Preserving Embedding regularization Sparse Coding algorithm(NPESC).Comparing with traditional sparse coding,it adds the Neighborhood Preserving Embedding(NPE) regularization into the objective function of sparse coding,so that the sparse codes of similar features remain similar by minimizing the deviation between the sparse code of every feature and its neighbors.Thus,this algorithm preserving the local neighborhood structure of the fertures.In addition,approximate coding is used.The result of applying this algorithm to image classification on several datasets,shows that the proposed to reduce computational complexity algorithm can achieve higher accuracy when compared with exissting sparse coding methods.
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Computer Engineering. 2016, 42(3): 236-241,248. https://doi.org/10.3969/j.issn.1000-3428.2016.03.043
As inaccurate similarity measurement fails in matching the appropriate sample patches,image completion algorithms based on patch match tend to cause inconsistent phenomenon on structures and textures when repairing the architectural scene images.In view of this,this paper presents an image completion method using image plane structure information to guide patch match.Begining with estimating plane projection parameters,the known region is segmented into planes,and the translational regularity among these planes is extracted.By means of defining the prior probabilities of the patch offsets and transformations,the plane structure information is converted into soft constraints to guide the ordinary patch match.Integrating the color item,plane item and gradient item into the patch distance function,it measures the similarity of patches,which helps to reduce the image blurring caused by inaccurate patch match.Experimental results suggest that,the proposed method is not only effective in completing the damaged image rapidly,but also able to guarantee the image’s structure continuity and texture smoothness.
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Computer Engineering. 2016, 42(3): 242-248. https://doi.org/10.3969/j.issn.1000-3428.2016.03.044
Existing image inpainting algorithms based on sparse representation do not distinguish structure patch and texture patch when constructing the learning dictionary.This may increase the processing time when inpainting the smooth part of the damaged region,and decrease the inpainting accuracy when inpainting the structure part.To solve this problem,this paper proposes an improved algorithm.It classifies the patches around the damaged region into two categories where one category includes structure patches while the other includes texture patches,and correspondingly constructs two kind of learning dictionaries.For structure patches,their corresponding dictionaries are used to ensure high accuracy.For texture patches,their corresponding dictionaries are used to accelerate inpainting under the condition of clear inpainted texture.Experimental result shows that the proposed algorithm can effectively inpaint the structure detail without increasing the complexity,while the inpainting effect is better with low time consumption.
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Computer Engineering. 2016, 42(3): 249-253. https://doi.org/10.3969/j.issn.1000-3428.2016.03.045
Location Map(LM) compression is the key issue of spatial domain watermark embedding.Aiming at this issue,a Difference Expansion(DE) optimization algorithm is proposed based on difference LM adjustment.Considering location distribution of extensible difference,some small continuous zero sets are all modified to acquire a lot of pure watermark payload space.Thus,difference LM is compressed more efficiently by some lossless compressors.At the same time,the quantities of embedded points are reduced and the Peak Signal to Noise Ratio(PSNR) is improved.Simulation results show that the proposed algorithm can significantly enhance the embedding performance of DE algorithm by an optimal or a preferred threshold for adjustment strength parameter.In this way,embedding Bits per Pixel(BPP) for pure payload is improved by 2.48 times to 5.26 times.Moreover,PSNR increases 4.4 dB to 8 dB.
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Computer Engineering. 2016, 42(3): 254-258,265. https://doi.org/10.3969/j.issn.1000-3428.2016.03.046
Owing to the traditional Sparse Representation-based Classification(SRC) algorithm can not extract image texture information comprehensively,the result of classification is not high.In order to solve this problem,the Local Binary Pattern(LBP) feature is added to the SRC model,and a novel sparse representation classification method is proposed.The LBP is used to extract the local texture of the remote sensing image and the LBP histogram is used to design a structured dictionary,which is more suitable for the remote sensing image.Compared with the Support Vector Machine(SVM) and K-nearest Neighbor(KNN) method,experimental results show that the proposed method can improve the classification accuracy.
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Computer Engineering. 2016, 42(3): 259-265. https://doi.org/10.3969/j.issn.1000-3428.2016.03.047
Shape from Focus(SFF) is a layer scanning technology,which reguires a lot of memory of upper computer when mehshring.To solve this problem,an algorithm based on spreading is proposed.Based on the interval property of the focus evaluation curve and the constraint of continuous surface,the algorithm initializes the spreading region using traditional methods,infers the depth of the spreading point utilizing the depth information of the spreading region,searches and confirms the depth of the spreading point within the search radius,and gets the more accurate depth value.Experimental result shows the proposed algorithm can reduce the inemory utilization by 9.6% averagely while ensuing the precision of shape recovery.
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Computer Engineering. 2016, 42(3): 266-271,277. https://doi.org/10.3969/j.issn.1000-3428.2016.03.048
Aiming at the slow running speed and the redundancy of parameters in common single frame Super Resolution(SR) algorithms,a single frame super resolution based on cross coupled dictionary is proposed,in which random forests is used to solve the problem of multi-term regression.The core issue of the coupled dictionary is introduced,that is the mapping problem of LR image patches to HR image patches.The close relationship between single-frame SR and local linear regression is given.A new regularization objective function is proposed,and the algorithm of random forest is used to optimize the regularization objective function.Experimental results show that compared with the algorithm of general Approximate Nearest Neighbour Field(ANNF),Neighbour Regression Example-based SR(NRESR) and the other algorithms,the proposed algorithm can obtain higher value in the aspects of Peak Signal to Noise Ratio(PSNR) and Structural Similarity Index Measurement(SSIM),and the image’s texture is much more natural.
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Computer Engineering. 2016, 42(3): 272-277. https://doi.org/10.3969/j.issn.1000-3428.2016.03.049The traditional denoising algorithm has residual noise after removing noise,and image denoising effect is not obvious for the large noise.Aiming at this problem,a new image denoising algorithm is proposed in this paper.In this algorithm,the input image with noise can be split into overlapped image patches.Through randomly selecting moderate image block to learn,an adaptive redundant dictionary can be got.Then the sparse representation coefficients can be obtained from this redundant dictionary with nuclear regularized orthogonal matching pursuit technology.Then the image can be restored by these coefficients.Experimental results show that compared with K-Singular Value Decomposition(K-SVD) algorithm,the Peak Signal to Noise(PSNR) of the proposed algorithm is better,the image detail and texture information can be well preserved.
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Computer Engineering. 2016, 42(3): 278-282. https://doi.org/10.3969/j.issn.1000-3428.2016.03.050
According to the low resolution characteristic of infrared video image,an improved super-resolution reconstruction algorithm of infrared video image is proposed in this paper.It researches the sparse representation for the low-resolution infrared video image patches,and gets the optimum coefficients of sparse representation by Least Angle Regression(LAR) algorithm.By reconstruction constraints,the final high-resolution video image can be obtained through the optimun coefficients.Experimental results show that,for infrared video images,the proposed algorithm can improve the resolution of the input image significantly and achieve better outcomes in visual effects and objective evaluation,compared with Bicubic,NE and UVII algorithms.
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Computer Engineering. 2016, 42(3): 283-288,294. https://doi.org/10.3969/j.issn.1000-3428.2016.03.051
Aiming at the insufficient information obtained by a single type of feature extraction method,this paper combines Autoregressive(AR) model and wavelet transform to implement feature extraction.The combined feature set is not directly utilized as input of classifier to identify,while the genetic algorithm is carried out for optimal feature subset selection.The motor imagery electroencephalogram signals are modeled using AR model.The estimated parameters are regarded as time-domain features.Combining time-frequency features of wavelet transform, the final feature set is constructed.Genetic Algorithm(GA) based on k-Nearest Neighbor(kNN) classification error as fitness function is employed feature selection.The Support Vector Machine(SVM) classification method is used to validate the feature selection results.Experimental results show that redundant and non-informative features are removed through the feature selection of genetic algorithm and the classification accuracy reaches 96.43%.
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Computer Engineering. 2016, 42(3): 289-294. https://doi.org/10.3969/j.issn.1000-3428.2016.03.052
In order to improve the diversity and safety of data encryption and decryption algorithms in cryptographic modules,this paper designs and implements a data processing module based on dual Field Programmable Gate Array(FPGA) and Digital Signal Processor(DSP) architecture.Two pieces of FPGA are interconnected with a DSP by External Memory Interface(EMIF) bus.FPGA 1# communicates with PC and DSP by PCIe and EMIF bus,and Scatter-gather Direct Memory Access(SG-DMA) is used for high-speed data transferring application.FPGA 2# realizes serial communication with FPGA 1# by AURORA protocol,makes multiple algorithms work in parallel,and supports global and partial reconfiguration of the algorithm.DSP realizes parameter configuration as well as key generation and management for data encryption and decryption algorithms.The driver and application software are designed on NeoKylin operating system to test the module’s function and performance.Results show that the rate of communication between the module and the host is up to 11.36 Gb/s,and the module has the characteristics of high safety and reconfiguration suitable for high-speed data co-processing field.
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Computer Engineering. 2016, 42(3): 295-300,307. https://doi.org/10.3969/j.issn.1000-3428.2016.03.053
The traditional indoor localization method based on Received Signal Strength Indication(RSSI) has many drawbacks,such as low localization accuracy,high hardware requirements,and complex algorithms.To resolve this problem,an indoor localization method based on fit model is proposed.The RSSI data are collected by low-cost Radio Frequency(RF) readers,and processed by low-complexity filter.Localization is then achieved by the distance loss model and the algorithm of fit model.In the actual indoor environment,Matlab simulation analysis results show that the average position error of all positioned targets is under 50 cm,and the average position error of 70% of the positioned targets is no more than 15 cm.This indicates that the proposed method can be applied to the actual indoor location environment.
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Computer Engineering. 2016, 42(3): 301-307. https://doi.org/10.3969/j.issn.1000-3428.2016.03.054
According to the features of downlink data of Landsat8 as well as the RICE lossless data compression algorithm and the CUDA programming technology,a real-time decompression processing system bsed on Graphic Processing Unit(GPU) is proposed.It adopts Compute Unified Device Architecture(CUDA) and pipelined decompression structure for task decompression and CUDA optimization.Experimental results show that the speed-up of the implemented decompression system is 7.45 times that of the CPU-based solution,and the processing rate is at least 1.8 times as high as that required by Landsat8 satellite downlink data real-time decompression.The decompressed image data has high accuracy with low cost.
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Computer Engineering. 2016, 42(3): 308-311,316. https://doi.org/10.3969/j.issn.1000-3428.2016.03.055
Aiming at the problem that a single sensor is difficult to describe the rotor vibration accurately,a full information fault diagnosis method of rotor based on improved D-S evidence fusion theory is proposed.Wavelet analysis and information entropy are combined to extract vibration signal full information fault feature vectors of each measuring point.And these feature vectors are made to be the input of the corresponding BP neural networks to get the original evidences of each measuring point.These original evidences are preprocessed by the conflict degree,and the new evidences are weighted average fused according to the credibility.Experimental results show that this method can obtain original evidences effectively and reduce the influence that comes from the evidence conflict,the accuracy rate of this method can reach 93%,and it is higher than that of the conventional BP method and BP-D-S fusion method.
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Computer Engineering. 2016, 42(3): 312-316. https://doi.org/10.3969/j.issn.1000-3428.2016.03.056
To handle the problem of node Simultaneous Localization and Tracking(SLAT) in Wireless Sensor Network(WSN),a distributed fusion algorithm is proposed,to overcome the approximate error caused by Taylor’s expansion,and achieve the desired tracking results when the movement pattern changes.The Interactive Multiple Model(IMM) based on Unscented Kalman Filtering(UKF) is adopted as local estimator.To fuse the local estimates of target track,the Internal Ellipsoidal Approximation Fusion(IEAF) is used at the fusion center.Monte Carlo simulation results show the effectiveness of the proposed approach,which has higher fusion accuracy of 33.56% than the Covariance Intersection(CI) in the scenario of tracking a maneuvering target,while obtaining better estimates of the node location.
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Computer Engineering. 2016, 42(3): 317-321. https://doi.org/10.3969/j.issn.1000-3428.2016.03.057
Departing vehicle flow calculation in marshalling stations is not only an important part of railway network vehicle flow calculation,but also the main content of station vehicle flow calculation.Its aim is to forecast each vehicle’s departing time based on the time that it arrives at the station.The model for departing vehicle flow calculation in marshalling stations is established according to requirements of regional vehicle flow calculation.This multi-objective non-linear model is turned into a standard mixed integer linear programming model by a few preprocessing changes,such as replacing its conditional restrictions and quadratic variables by adding new 0-1 variables.The IBM ILOG-CPLEX optimizer is chosen to solve the new model.Calculation results on marshalling station case show that the pretreatment method and calculation method are in accordance with the expected output of the model,and the optimal solution search time is fast.
Volume 50 No 3
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