15 January 2016, Volume 42 Issue 1
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Computer Engineering. 2016, 42(1): 1-6. https://doi.org/10.3969/j.issn.1000-3428.2016.01.001For solving the problem of node resources optimization in Hadoop platform,this paper proposes a MapReduce parameter optimization strategy.When a new job is submitted,it first gets feature value of resource utilization,and then calculates the relative distance with the jobs in the signature database.At last,it selects the configuration of the job with the minimum relative distance as the optimal configuration.If the configuration is not found,it gets optimal configuration by the way of iteration and then updates the feature database.Experimental results show that the proposed strategy can effectively improve the efficiency of job execution and reduce the execution time compared with the default parameter configuration.
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Computer Engineering. 2016, 42(1): 7-10. https://doi.org/10.3969/j.issn.1000-3428.2016.01.002F-gate and interpolation method are common reduction techniques in process of Holant dichotomy theorem’s proof,and Gadget computation plays an important role.In order to increase the computational efficiency of Garget,this paper proposes a general algorithm based on edge enumeration and matrix computation.But the general algorithm only computes in exponential time,so aiming at this problem,this paper proposes an accelerative algorithm by introducing the special function.It calls special functions according to the degrees of freedom,which makes Holant problems be solved in polynomial computation time.Moreover,this paper finds that Gadget computation can be extended to Holant(F∪［1,1］) problem,and the accelerated algorithm can also show the tractable families of the problem.
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Computer Engineering. 2016, 42(1): 11-17. https://doi.org/10.3969/j.issn.1000-3428.2016.01.003Aiming at single objective optimization problem,a Web Service Combination(WSC) scheduling method based on game theory and multi-objective Mixed Integer Linear Programming(MILP) is proposed.The Quality of Service(QoS) attributes of WSC are defined according to five basic QoS attributes.WSC scheduling problem is converted to the multi-objective optimization problem considering QoS.The interaction between service providers is simulated as a non-cooperative and incomplete Bayesian countermeasure.The competition strategy is guaranteed by the Bayesian Nash equilibrium of participants when service provider executes tasks.Thus,the execution time and execution cost is minimized,the reputation,reliability and availability are maximized at the same time.The numerical analysis result shows that the proposed method has a high solving efficiency,can avoid the aggregation problem of multiple attributes in utility function,and it is suitable for solving the small and medium size WSC scheduling problems.
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Computer Engineering. 2016, 42(1): 18-24,30. https://doi.org/10.3969/j.issn.1000-3428.2016.01.004In traditional similarity join algorithms,data partition and refined calculation are isolated.During the refined calculation phase,all pairs of data in the same partition need to be compared with each other which leads to a large number of comparison computations.In order to solve this problem,this paper designs a new memory index:DistanceTree,and proposes an in-memory similarity join algorithm based on it.This algorithm distributes data into different partitions according to the potential distribution of data,ensures the data with same similarity to the same or adjacent partitions,and saves the calculation results of partition phase through the tree node location information.By leveraging the calculation result,only pairs of data in the same or adjacent leaf nodes need to be compared.Experimental results show that similarity join algorithm based on DistanceTree is 2 times~3 times more efficient than TOUCH algorithm and also is more scalable.
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Computer Engineering. 2016, 42(1): 25-30. https://doi.org/10.3969/j.issn.1000-3428.2016.01.005Aiming at the problem that traditional underwater acoustic imaging de-noising algorithms can not effectively suppress the additive noise and multiplicative noise at the same time,a 3D visualized underwater acoustic data de-nosing algorithm based on fuzzy median filtering and wavelet soft-threshold filtering is proposed.This algorithm analyzes the characteristics of composite noise model,and divides the 3D data into several 2D data in the concrete operating process.In order to hierarchically remove the additive and multiplicative noise in the underwater acoustic data,it adopts a 3D filter window in the implementation of fuzzy median filtering,and not only considers the inter-scale correlation of wavelet coefficients of 2D plane data,but also considers the correlation of wavelet coefficients of adjacent plane data in the process of soft threshold filtering.Experimental results show that the proposed algorithm reduces the noise in the original data,improves the data continuity and contrast,and it provides a good visual conditions for the observation and detection of underwater acoustic target.
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Computer Engineering. 2016, 42(1): 31-35,40. https://doi.org/10.3969/j.issn.1000-3428.2016.01.006Spark is a kind of efficient big data processing platform based on memory and similar to Hadoop MapReduce.But the Spark default task scheduling strategy does not take the different capacity of node into account for heterogeneous Spark cluster,thus leading to the low system performance.For this problem,this paper presents an adaptive task scheduling strategy for heterogeneous Spark cluster,which analyzes parameters from surveillance to dynamically adjust the task allocation weights of nodes through monitoring the load and resource utilization of nodes.Experimental result validates that this strategy for heterogeneous nodes is superior to the default task scheduling strategy in aspects like task completion time,nodes working state and resource utilization.
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Computer Engineering. 2016, 42(1): 36-40. https://doi.org/10.3969/j.issn.1000-3428.2016.01.007For the traditional collaborative filtering recommendation algorithm meets with low recommendation accuracy and sparse matrix problem.An improved collaborative filtering recommendation algorithm is proposed.It integrates user preference on item attribute and item popularity to compute the user preference degree on item,and fills the unrated-items through the sum of user preference value and average score of users.It takes user interests change over time into account,then the time function as a weight factor in similarity calculation and recommendation process is used to find nearest neighbor set,and it achieves the optimal recommendation.Experimental result shows that this algorithm accurately reflects the change trends of user interest,and not only alleviates the sparsity matrix problem effectively,but also improves recommendation accuracy.
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Computer Engineering. 2016, 42(1): 41-45,50. https://doi.org/10.3969/j.issn.1000-3428.2016.01.008In the process of using the information management system based on B/S structure,users are facing a lot of forms to fill in and data to entry during use.But the traditional methods of form filling and data entry are always by manual,which causes many problems such as low input efficiency and inaccurate entry.Through the study of real-time prediction capabilities of search engines and recommendation system,this paper proposes a recommended entry model based on Reverse Nearest Neighbor(RNN) collaborative filtering.It introduces the architecture and implementation process,and based on this,proposes an RNN collaborative filtering algorithm.By using this algorithm to obtain recommended results which are based on user behavior,the personalized recommendation can be applied to the field of data entry and form filling.Experimental results show that the proposed model can effectively improve the efficiency of the data entry and accuracy of the entry results.
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Computer Engineering. 2016, 42(1): 46-50. https://doi.org/10.3969/j.issn.1000-3428.2016.01.009As Reduced Instruction Set Computer(RISC) architecture processors generally use fixed-length instructions,they have to perform the function of long jump instruction in Complex Instruction Set Computer(CISC) architecture processors by a literal pool.This paper proposes an optimized method dealing with the management of addresses immediate value in C-SKY CPU.On one hand,the new algorithm validates every constant address,splits the appropriate ones and stores the common base addresses to reduce the number of memory access instructions,on the other hand,by sharing the common base addresses between different functions,the memory consumption can be reduced further.Experimental result shows that to some drivers,this method can reduce the code size by 3.77%.
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Computer Engineering. 2016, 42(1): 51-55. https://doi.org/10.3969/j.issn.1000-3428.2016.01.010Technique of hardware data prefetching loads data to Cache before they are actually referenced by processor,thus improves the system performance.Existing research and application focus on prefetching data only to the first level Cache.In this way,the prefetched data may arrive at Cache after they are used and decrease the performance of hardware data prefetching.This paper proposes a technique of prefetching multiple levels of Caches based on a stream-based prefetcher.Performance analysis for SPEC CPU2000 shows that the proposed technique can improve the performance of integer applications by 2.11% on average,11.19% at most,float applications 3.08% on average,12.77% at most,compared with only prefetching the first level Cache.
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Computer Engineering. 2016, 42(1): 56-60,65. https://doi.org/10.3969/j.issn.1000-3428.2016.01.011Aiming at the problem that pedestrian detection scheme based on Histogram of Oriented Gradient(HOG) has large computation and poor real-time,this paper designs a HOG feature extraction normalized module embedded Support Vector Machine (SVM) classifier,and applies it to pedestrian detection.It proposes a two-stage pipeline architecture.On the first level,it uses 16×16 pixel scanning,simplifies the histogram generation with Look-up Table(LUT),and it can reduce resources consumption of multiplier.On the second level,the 15-way parallel SVM is embedded itself in the HOG normalization module,and it can reduce bit of 15-way parallel SVM multiply-accumulator through pre-start SVM.Also,an algorithm is proposed to automatically reduce duplicated detection to improve detection accuracy.The scheme is verified for SVGA resolution video(800×600) at 47 frames on Spartan6 Field Programmable Gate Array(FPGA) with 100 MHz and it improves the real-time and accuracy of pedestrian detection.
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Computer Engineering. 2016, 42(1): 61-65. https://doi.org/10.3969/j.issn.1000-3428.2016.01.012Aiming at the features of multi-level security architecture,and the remote debugging technology based on the Multiple Independent Levels of Security(MILS) multilevel security architecture,this paper proposes a unified management and synergic debugging mechanism based on the Target Communication Framework(TCF) framework.By transforming the TCF framework,it realizes the application partition independent debugging which meets the MILS Partition Communication System(PCS) security requirements.It also achieves multi-partition collaborative debugging by improving the traditional hardware JTAG debugging.Analysis results show that the mechanism not only satisfies the safety requirement of MILS,but also solves the MILS system development and the remote embedded debugging problem of single partition application development.
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Computer Engineering. 2016, 42(1): 66-70,76. https://doi.org/10.3969/j.issn.1000-3428.2016.01.013Aiming at the problem that USBKey equipment power acquisition is difficult,a new power consumption acquisition method is proposed.Through the PC software and Microprogrammed Control Unit(MCU),this method uses PC to send delay command to MCU.MCU sends trigger signal according to the order contents delay,so as to ensure the synchronization of trigger signal and the cipher algorithm,and to meet the needs of different USBKey equipment.It designs power supply system of acquisition equipment,and is powered by capacitance.It reduces the noise by external power source.Through adding PC software runtime library,it expands this method to any USB interface equipment.It makes power acquisition for commercial USBKey equipment.Experimental results show that this method can accurately acquire power consumption information,and isolates the noise.
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Computer Engineering. 2016, 42(1): 71-76. https://doi.org/10.3969/j.issn.1000-3428.2016.01.014This paper applies the hypergraph model to design automatic software module partition algorithm.Under the hypergraph modeling,each significant class extracted from the source codes of an analyzing software system is abstracted as a vertex of a hypergraph,and hyperedges are built among the classes which have relations to some extent.Then the problem of module partition is translated into a partitioning problem of a hypergraph,which can be solved by hypergraph partitioning algorithm.In order to improve the partitioning result,a new modularity function is constructed according to the cohesion states and coupling relations in and among software modules.Compared with hMetis algorithm,experimental results show that the proposed algorithm can obtain reasonable and effective module partition.
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Computer Engineering. 2016, 42(1): 77-82. https://doi.org/10.3969/j.issn.1000-3428.2016.01.015On account of the high energy consumption of Routing Protocol for Low Power and Lossy Network(RPL),an improved RPL protocol is proposed in this paper.It identifies the energy bottleneck nodes,minimizes the energy consumption of bottleneck nodes.The new protocol defines the Expected Lifetime(ELT).Then it uses ELT as metric to estimate the lifetime of those bottleneck nodes.Moreover,it takes into account both the amount of traffic and link reliability to estimate how much energy such a bottleneck node consumes on average to realize balancing energy consumption.It constructs the Directed Acyclic Graph(DAG) based on ELT criteria to carry out RPL protocol.Simulation results show that the proposed protocol performs better than link quality-based RPL and residual energy-based RPL in network lifetime.
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Computer Engineering. 2016, 42(1): 83-88. https://doi.org/10.3969/j.issn.1000-3428.2016.01.016For the problem of the balance between Quality of Service(QoS) and energy consumption of the nodes in aggregation algorithm which is conducted in the wireless multi-hop network,a cost function and performance optimization scheme of packet aggregation algorithm is proposed.The impact of the number of aggregation packets on quality of service and nodes energy consumption is analyzed,and the cost function is utilized to merge the two values into a function.The optimal value of the cost function is also the optimal value of the balance between QoS and energy consumption of the nodes,and it can get the optimal value of the number of aggregation packets.Proposed scheme is realized by simulate to verify the effectiveness of the proposed scheme.Simulation results show that the proposed scheme can balance the QoS and energy consumption.
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Computer Engineering. 2016, 42(1): 89-94,102. https://doi.org/10.3969/j.issn.1000-3428.2016.01.017According to the characteristics of Medium Access Control(MAC) layer protocol in mobile Ad Hoc network,combining with the actual engineering requirements,N-time Division Multiple Access(TDMA) dynamic slot allocation protocol based on I-sequential Vertex Coloring(SVC) algorithm is proposed.The protocol frame structure,interaction and dynamic slot allocation algorithm are specifically analysed and described.This protocol is simulated under NS2,results show that the algorithm has better performance on high slot utilization,throughput,average latency,fairness and other parameters than IEEE802.11 and Time Division Multiple Access(TDMA) protocols.
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Computer Engineering. 2016, 42(1): 95-102. https://doi.org/10.3969/j.issn.1000-3428.2016.01.018
Existing researches on Channel-hopping Sequence(CHS)-based blind channel rendezvous strategies only focus on the access negotiation problem of Media Access Control(MAC) protocol in Cognitive Radio Networks(CRNs),and they ignore the study of related access control.For the false collision problem in Carrier Sense Multiple Access with Collision Detection(CSMA/CA) MAC protocol,a probabilistic regulation mechanism of doubling contention window size is proposed,which named p-DOUBLE.As false collision does not occur in the hop slot when a sender-receiver pair achieves rendezvous,it employs the rendezvous probability of existing CHS-based blind rendezvous strategies in each hop slot to double the contention window size,which effectively alleviates the impact of false collision on extending backoff counting-down process and increases the probability of seizing transmission opportunity when the sender-receiver pair achieves rendezvous.By comparing with traditional deterministic regulation mechanism of doubling contention window size,which named 1-DOUBLE,experimental result shows that p-DOUBLE can reduce packet delivery delay by 14%~20% and increase network throughput by 17.1%~29.3%.
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Computer Engineering. 2016, 42(1): 103-108. https://doi.org/10.3969/j.issn.1000-3428.2016.01.019The Transmission Control Protocol(TCP) can not show good performance in the complicated wireless channel network,so that the throughput of the network decays remarkably.Aiming at this problem,this paper analyzes the reasons affecting the network transmission performance firstly,and then summarizes some improved mechanisms of TCP to the questions,such as packet loss which is caused by high bit error rate and link outage,and delay jitter which is due to band competition.The comparative result indicates that the improved mechanisms can adapt the wireless network environment much better than the traditional TCP and improve the throughput of network.
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Computer Engineering. 2016, 42(1): 109-115. https://doi.org/10.3969/j.issn.1000-3428.2016.01.020
Aiming at the client allocation problem in 3D Virtual World(VW),an allocation approach based on two-stage is proposed.The concrete implement is that the client allocation problem is divided into the initial allocation stage and refined allocation stage.The objective is that the total number of clients with Quality of Service(QoS) is maximized and the allocation cost is minimized.In the initial allocation stage,a target server is found for each client and then in the refined allocation stage,a contact server is found for each client.In the simulations,four algorithms for the two-stage allocation are simulated,and the results show that the algorithms that take into account network delays in the initial allocation stage significantly outperform those which do not.Moreover,the algorithms can well adapt to the dynamic change characteristics of VW.The performances for the allocation approach based on two-stage proposed are compared with which for the other two algorithms used widely at present,the results show that the allocation approach proposed in the average network communication delay and resource consumption outperforms the other two client allocation algorithms used widely.
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Computer Engineering. 2016, 42(1): 116-120,127. https://doi.org/10.3969/j.issn.1000-3428.2016.01.021With the development of social networks,the issues of privacy preservation arouse extensive attention.It can cause privacy disclosure of the shortest path if weighted social network data are protected before its publication.In order to solve this issue,this paper proposes a k-shortest paths candidate anonymity model and develops a shortest path greedy generalization based algorithm to achieve this model.A generalization is made on the weight of top-k path of target nodes.The generalization interval of non-overlapping edges between shortest paths and top-k paths is adjusted,according to the candidate anonymous interval.There are k shortest paths between target nodes,which limit the probability of shortest path being re-identified to 1/k.Experimental results demonstrate that the change of edge weight distribution,error rates for query and error accumulation of the proposed algorithm are significantly less than k-possible path anonymity algorithm and k-multiple path anonymity algorithm.The proposed algorithm can effectively achieve shortest path anonymity.Meanwhile,it can keep the structure of graph not being changed.
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Computer Engineering. 2016, 42(1): 121-127. https://doi.org/10.3969/j.issn.1000-3428.2016.01.022In order to avoid the adverse effects of the Primary User Emulation Attack(PUEA) in Cognitive Radio(CR) network,an authentication scheme based on Hash chain is proposed.Two occasions are considered in this scheme,one is PUEA between primary users and primary user base station,the other is between primary user base station and secondary users.In the view of the former,the paper adopts the self-updating Hash values to realize the signal verification,while dealing with the latter by issuing the Hash chain in a reversed way.This scheme makes the best of Hash characteristics of the irreversible and the forgery prevention to ensure the security,while the properties of self-updating reduce the storage content and simplify the validation process,so that the overhead of system can be reduced and the efficiency of the scheme can be guaranteed.Analysis shows that this scheme can solve the PUEA in CR network effectively.
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Computer Engineering. 2016, 42(1): 128-132,137. https://doi.org/10.3969/j.issn.1000-3428.2016.01.023With the further improvement of design,manufacture and test separation in Integrated Circuits(IC),hardware trojans can be implemented as modifications to IC,and it raises numerous concerns regarding possible threats.This paper briefly explains the concept of hardware trojans,and explains the countermeasures technology of hardware trojan attacks and the importance of conducting out the countermeasures against hardware trojans.Also it introduces the classification of the state-of-art countermeasures,deeply analyzes the side-channel analysis method and the design for security method.Analysis results show that the designers must consider circuit security problem in designing circuits in onder to the security of integrated circuits,meanwhile they begin test works ensure after chips are completed.
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Computer Engineering. 2016, 42(1): 133-137. https://doi.org/10.3969/j.issn.1000-3428.2016.01.024Due to its low cost and convenience,Radio Frequency Identification(RFID) technology is widely deployed in social life.In time-sensitive large-scale RFID applications,efficient RFID missing tag detection is a key problem.Based on analysis on recent research,a detection method based on iterative update is proposed.The method makes use of history information in each round,and acquires more information in empty slot,singleton slot and collision slot to identify more existing or missing tags,which improves the efficiency of detection.Compared with IIPS-CM protocol,it achieves higher performance as well as good stability under various rates,and does not change the number of missing tags.
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Computer Engineering. 2016, 42(1): 138-144,149. https://doi.org/10.3969/j.issn.1000-3428.2016.01.025A new Chinese free text continuous authentication method based on Manhattan distance is proposed to analyze typing rhythm of users when they use social network services to communicate with others in Chinese.Experimental results show that the method controls the False Accept Rate(FAR),False Reject Rate(FRR) and Equal Error Rate(EER) so that it can be used for user continuous authentication and intrusion detection when user typing samples are written in Chinese to protect people from important and crucial information being leaked.
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Computer Engineering. 2016, 42(1): 145-149. https://doi.org/10.3969/j.issn.1000-3428.2016.01.026As Chinese state encryption administration is seeking the next generation of Digital Signature Standard(DSS),this paper analyzes and compares seven DSS listed in ISO/IEC 14888-3 and SM2 which are based on Discrete Logarithm Problem(DLP) or Elliptic Curve Discrete Logarithm Problem(ECDLP).Results show that the widely used Digital Signature Algorithm(DSA) is a combination of Schnorr and ElGamal signature algorithm and it becomes Elliptic Curve Digital Signature Algorithm (EC-DSA).SM2 may be more vulnerable than EC-DSA.Moreover,the Pointcheval/Vaudenay algorithm is provably secure.The Korean Certificate-based Digital Signature Algorithm(KCDSA) and its elliptic curve version Elliptic Curve Korean Certificate-based Digital Signature Algorithm(EC-KCDSA) performs better both in security and efficiency issues.The signature algorithms of Elliptic Curve Russia Digital Signature Algorithm(EC-RDSA) and Elliptic Curve Germany Digital Signature Algorithm(EC-GDSA) are faster.It is worth noting that an attack against EC-RDSA is proposed,implying that EC-RDSA is not strongly existential unforgeability under the adaptive chosen-message attack.The comparative results is helpful for the research,as well as for the finalization of the next generation of DSS.
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Computer Engineering. 2016, 42(1): 150-155. https://doi.org/10.3969/j.issn.1000-3428.2016.01.027Existing multi-receiver signcryption schemes exist some security problems.For example,multi-message can not be broadcast simultaneously and the receivers do not have fairness in decryption.In order to avoid those problems,this paper proposes a multi-message and multi-receiver hybrid signcryption scheme based on Discrete Logarithm(DL).In this scheme,a sender can simultaneously signcrypt n messages for n receivers,and a receiver only can correct unsigncrypt the ciphertext to get his message with his own private key.Meanwhile,the proposed scheme of confidentiality and unforgeability is proved in the random oracle model.The results show that the new scheme not only is more efficient than other signcryption schemes,but also has a lower computation and communication overhead,and it can guarantee the communication security,reliability and fairness.
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Computer Engineering. 2016, 42(1): 156-162. https://doi.org/10.3969/j.issn.1000-3428.2016.01.028
The k-error linear complexity is used as an important stability index of pseudorandom sequences,and the critical error linear complexity distribution characterize the descent point of k-error linear complexity.This paper studies the 2 n-periodic binary sequences that k-error linear complexity with second descent point (critical point) via cube theory and sieve method.By analyzing the k-error linear complexity with first descent point k=4 and second descent point k′ =6,the relationship between linear complexity of sequences and linear complexity of the first descent point is established,being given the possible value forms of the first descent point linear complexity.It obtains the counting functions of periodic binary sequences when being given first descent point linear complexity and second descent point linear complexity.Analysis result shows that periodic binary sequences can be studied with third descent point (critical point) of k-error linear complexity by the same methods.
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Computer Engineering. 2016, 42(1): 163-167. https://doi.org/10.3969/j.issn.1000-3428.2016.01.029Infectious disease prediction is an important field in time series prediction,owing to the problem of lower disease forecast precision,a method that calculates the similarity of the data in the same month by K-nearest Neighbor(KNN) algorithm based on data division is proposed.This method divides diarrhea data by month,and gets the same month time series data in different years.It uses KNN method to calculate similarity of time series,and gets the most similar time series.Forecast sequence is obtained by the most similar time series.An experiment is done based on the data of diarrhea in Shanghai,experimental result shows that the method can fully take an impact on the number of diarrhea of season into account,compared with the continuous time series prediction algorithm based on KNN,MAE is less than 38.52,MPE is less than 0.07 and RMSE is less than 47.86,and compared with the traditional forecasting methods of ARIMA,MAE is less than 23.04,MPE is less than 0.07 and RMSE is less than 28.12.
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Computer Engineering. 2016, 42(1): 168-173. https://doi.org/10.3969/j.issn.1000-3428.2016.01.030Extreme Learning Machine(ELM) and Sparse Representation based Classification (SRC) algorithm are applied to face recognition widely.ELM has speed advantage while it can not handle noise well,whereas SRC shows significant robustness to noise while it suffers high computational cost.According to the advantages and disadvantages of two algorithms,this paper proposes a hybrid approach combining extreme learning machine and Subspace Pursuit(SP) for face recognition,which incorporates their respective advantages and uses subspace pursuit method to optimize solving sparse representation coefficients in SRC.According to the analysis of ELM actual output to estimate whether the test sample is a noisy image,clean image directly uses ELM actual output to classify,and noisy image applies SP with SRC method to classify.Experimental results show that the novel algorithm has high recognition rate and speed advantage in face recognition on extended Yale B and ORL face database respectively.
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Computer Engineering. 2016, 42(1): 174-179. https://doi.org/10.3969/j.issn.1000-3428.2016.01.031The challenge of traditional collaborative filtering recommendation algorithms is data sparsity and limited user-preference information that is available.With the rapid development of the Internet,users can take the initiative to establish contact with other users who are trustworthy and have similar ideas.Some users may establish links which are unreliable.To overcome the impact of data sparsity and unreliable links on traditional social networking recommen-dations,this paper presents a recommendation algorithm based on trust relationships rebuilding and social networks transferring.It uses the method,called discarding the false and retaining the true,to solve the phenomenon of unreliable links.Meanwhile,it uses the improved jaccadr coefficient based on the scale of link to improve the accuracy of discarding the false and retaining the true.It defines the concept of probationary friends to reduce problem of data sparsity.It uses the transitivity of social network based on the new rebuilded social network to predict and define the concept of two-terminal distribution function and to adjust the predict scoring and improve the predict accuracy.The proposed algorithm is experimented in real Epinions datasets.Experimental results show that the algorithm can reduce the negative impact of the phenomenon of unreliable links and data sparsity,effectively lower the mean absolute error of prediction consequences,and enhance recommendation precision.
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Computer Engineering. 2016, 42(1): 180-186. https://doi.org/10.3969/j.issn.1000-3428.2016.01.032Massive social event relevant messages are generated in online social media,which makes the filtering and screening of them be a challenge.In order to obtain massages with high quality,a high quality information extraction framework based on Kernel Principal Component Analysis and Wavelet Transformation(KPCA-WT) is proposed.Based on multiple features fusion,the paper designs an algorithm to extract the microblogs of high quality,which transforms the features into wavelet domain to capture the details differences between the feature signals.The features’ weights are evaluated by employing Expectation Maximization (EM) algorithm and fused further to get a comprehensive value of each message,in order to reduce the effect of noise features,and to speed up the operation,the features are transformed through KPCA.Experimental results show that the proposed framework can extract information with higher quality and greatly reduce the time consumption.
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Computer Engineering. 2016, 42(1): 187-192. https://doi.org/10.3969/j.issn.1000-3428.2016.01.033In order to correct the classical errors made by young users in writing Chinese character,this paper puts forward an improved automatic teaching method for writing Chinese character.This method constructs teaching knowledge composed by dominant and binding stroke order,uses the teaching knowledge to monitor and manages the writing process through tabulation.It designs the link chain of strokes to track the stroke,uses traditional ways of identifying stroke errors to analyze the stroke relations,builds the mechanism of wrong intersections and separation to monitor the reverse writing and sets the part marks to instruct the part relations.Experimental result shows that the improved method can realize the automatic error-correct teaching of strokes,stroke relations,wrong intersections and separation,and parts relations.The correct rate of monitoring is up to 93%.
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Computer Engineering. 2016, 42(1): 193-198. https://doi.org/10.3969/j.issn.1000-3428.2016.01.034Aiming at the satellite resource scheduling problem of multi-space target,this paper designs Dynamic Matrix Cluster(DMC) encoding method,and proposes a satellite resource scheduling algorithm based on Pareto front and Particle Swarm Optimization(PSO).It uses Pareto front to keep a set of optimal solutions,avoids getting stuck in local optimization,also leads to more optimal solutions diverse in different index optimization priority.Then it selects the optimal solution according to user preferences and real-time requirements.Experimental results indicate that the algorithm can reduce the time consumption of temptation,judgment,and adjustment during particle swarm evolution process,and it has high resource utilization and stability compared with satellite resource schedulling algorithm based on traditional integer encoding.
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Computer Engineering. 2016, 42(1): 199-202,209. https://doi.org/10.3969/j.issn.1000-3428.2016.01.035The existing Collaborative Filtering(CF) recommendation algorithms are not taken into account the latent information of users’ aversion to items in the users’ browsing history and the difference between old users’ interests and new users’ interests in items of different popularity.To solve the problem,this paper proposes a collaborative filtering algorithm based on similarity extension and interest degree scaling.It extracts the latent information of users’ aversion to items from the users’ browsing history to calculate the items’ similarity of user’ aversion,and combines it with items’ similarity of users’ favorite to get the integrated similarity of items.On the basis of that,the algorithm scales the users’ interest degree to the items by preference factor which can reflect the difference between new users’ interests and old users’ interests in both popular items and unpopular items.Experimental results show that this algorithm improves the recommendation precision,recall rate and coverage,without obviously increasing in time-space complexity.
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Computer Engineering. 2016, 42(1): 203-209. https://doi.org/10.3969/j.issn.1000-3428.2016.01.036Aiming at the problem that the Density Based Spatial Clustering algorithm of Application with Noise(DBSCAN) can not find clusters of varied densities,this paper proposes a density clustering algorithm with initial points optimization and parameter self-adaption.It uses the method of optimization initial points to find the maximum density point in the current global datasets,and adaptively calculates the parameters of DBSCAN for the current cluster with the features of the current maximum density point and current datasets.These parameters are found to be different with the other clusters’ parameters,and the high-density cluster gets priority processed,so this algorithm can find clusters of varied density.Experimental results demonstrate that the improved algorithm can find clusters of arbitrary shape,size and density,enhance the ability to deal with overlapping data and uneven density in the cluster,and get clustering in higher accuracy.
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Computer Engineering. 2016, 42(1): 210-214. https://doi.org/10.3969/j.issn.1000-3428.2016.01.037In sequence image matching application,the disadvantages of the Minimum Intensity Change(MIC) algorithm,such as having no rotational invariance,missing many corners and being susceptible to noise,reduce the accuracy and spead of feature point detection.In order to solve this problem,the MIC algorithm is improved,and a fast image matching algorithm is proposed in conjunction with Speed Up Robust Feature(SURF) algorithm.Self-adaption smoothing filtering is processed in images,then by applying 8-neighborhood pixel similarity method,necessary geometric corners are detected in the non-flat areas of the image,finally after SURF algorithm is applied,feature points detected are described and matched.Experimental results indicate that compared with SURF and Smallest Univalue Segment Assimilating Nucleus-speed Up Robust Feature(SUSAN-SURF),this algorithm can improve the speed and accuracy of image matching under the changes about image rotation,noise,intensity and affinity.
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Computer Engineering. 2016, 42(1): 215-219. https://doi.org/10.3969/j.issn.1000-3428.2016.01.038Grayscale fault leads to too much contrast enhancement and detail deficiency.Aiming at this problem,this paper puts forward an image enhancement algorithm based on mathematical morphology.It uses mathematical morphology operation to enhance image contrast,combines the integrity and detail for the advantages of histogram equalization,and makes uniform distribution between the equalization of histogram grayscale,so as to achieve the purpose of retaining information.Experimental results show that the algorithm can solve the problem of fault gray levels,compared with the traditional histogram equalization algorithm,and it can obtain enhancement image with details outstanding and natural soft.
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Computer Engineering. 2016, 42(1): 220-224. https://doi.org/10.3969/j.issn.1000-3428.2016.01.039For reducing the impact on the performance of moving object detection by dynamic background,a moving object detection method is proposed.This method is fused with Self-organizing Retinotopic Maps(SORM) background model and Discrete Time Cellular Neural Network(DTCNN) thresholding model,builds background model according to SORM,ameliorates DTCNN in terms of requirement of moving object detection,constructs thresholding model to remove noise during the process of moving object detection,and updates the parameters of SORM and DTCNN models to adapt scene change.Experimental results show that this method has better performance of object detection,especially has stronger adaptation capacity for dynamic background,compared with traditional methods such as Gaussian mixture model,self-organizing background subtraction and growing self-organizing maps.
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Computer Engineering. 2016, 42(1): 225-230. https://doi.org/10.3969/j.issn.1000-3428.2016.01.040In view of the problems of pollution level detection of the traditional method,such as poor real-time performance,fan out from point to area,and higher cost,this paper presents haze pollution detection algorithm based on the image gray differential statistics.Using the characteristics that human eye can be used for haze pollution identification,the image is assigned by slicing under the RGB space,followed by the use of the image gray differential statistical method for image processing,calculation of entropy characteristic parameters for the processed image,the final image by calculating the distance to Canberra haze of pollution classification.Experimental results show that the algorithm can effectively identify fog and haze,with a high recognition rate,and high real-time characteristics.
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Computer Engineering. 2016, 42(1): 231-236,242. https://doi.org/10.3969/j.issn.1000-3428.2016.01.041Aiming at the disadvantages of the existing Graph Partitioning Change Detection(GPCD) algorithm like repeated segmentation and ignoring change cost of images,it employs probabilistic trees to represent probabilistic models of graph partitioning structures.Then reduce GPCD into the issue of detecting changes of trees on the basis of the Minimum Description Length(MDL) principle.It proposes TREE algorithm for solving the GPCD problem.Simulation experimental results show that,by taking the cost of changes into consideration,TREE realizes significantly less False Alarm Rate(FAR) for change detection than the baseline method called GraphScope.And it is able to detect changes more accurately than GraphScope.
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Computer Engineering. 2016, 42(1): 237-242. https://doi.org/10.3969/j.issn.1000-3428.2016.01.042This paper analyzes the local color correlation and the influence of blur forgery operation on image color consistency,and proposes a new method based on the improvement of the color features to detect the blur tamper of digital image.By redefining the normal of hue bias rate and abnormal hues rate.It extracts the hue bias and abnormal hue features to describe the destruction of the local color consistency introduced by imaging pipeline which is caused by blurring operation.These features are fed to the Support Vector Machine(SVM) to train and classify,and it realizes position detection for image blur forgery regions.Experimental results show that the proposed method has a good performance in detecting blur forgery operation,it can accurately locate the regions of blur forgery,and this method also has a certain robustness of the rotating and JPEG compression operation in tampered regions.
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Computer Engineering. 2016, 42(1): 243-247,253. https://doi.org/10.3969/j.issn.1000-3428.2016.01.043The image filtering experiment shows that the traditional Mean Shift(MS) algorithm regards noise pixel as image edge,so that the noise pixel is retained.Aiming at this problem,the paper designs a new simplified bilateral filtering method(ANBF),which is combined with the MS algorithm,and proposes an improved MS algorithm for image filtering.Kernel function is used firstly in the ANBF to find the noise and generate marking graph.Then ANBF locates and eliminates the noise according to marking graph.The MS algorithm uses the kernel function to find image mold,and then eliminates the noise according to image mold.The ANBF algorithm is embedded in traditional MS algorithm to improve MS algorithm for noise elimination capacity.Experimental results show that compared with the traditional MS image filtering algorithm,this algorithm can effectively overcome the MS algorithm’s weakly eliminating noise ability,and has higher noise eliminating rate.
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Computer Engineering. 2016, 42(1): 248-253. https://doi.org/10.3969/j.issn.1000-3428.2016.01.044The objects under complex environment often are affected by occlusion,illumination changes and so on,which lead to tracking drift.In order to improve the accuracy of visual tracking,a novel robust visual tracking algorithm is introduced by using Low-rank Sparse Representation(LRSR) and using Weighted Incremental Principal Component Analysis(WIPCA) method as the model updating mechansim.This algorithm uses Principal Component Analysis(PCA) base vector templates and square templates to model the target appearance,and considers the object tracking problem as the low-rank sparse optimization problem.It solves the low rank sparse solutions,gets candidate target reconstruction coefficient,then it considers the tracking target which is based on the reconstruction error and the posterior probability is the smallest as the current tracking results.At last during the process of WIPCA updating base vector template,it weights each trace object,in order to effectively restrain the influence of low quality target samples.Experimental results show that compared with Incremental Learning for Robust Visual Tracking(IVT) and Least Soft-thresold Squares Tracking(LSST),etc,this algorithm has better robustness in the target tracking of complex environment.
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Computer Engineering. 2016, 42(1): 254-259. https://doi.org/10.3969/j.issn.1000-3428.2016.01.045Aiming at the motion blur,a new blind deblurring algorithm is proposed,which is based on the L0 regularization restraints and the prior knowledge of natural image gradient distribution to obtain the real motion kernel.In the proposed methods,T-smooth technology is employed to screen the effective edge which is advantageous to estimate motion information.The refined motion kernel and a clean image are approximated by iterations.The bilateral filter is applied to non-blind deconvolution in order to inhibit the ringing effect.Experimental results demonstrate that compared with the previous approaches,the algorithm can effectively remove the motion blur and suppress the ringing effect.It is also shown that the proposed algorithm generates higher quality deblurring results than the existing algorithms.
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Computer Engineering. 2016, 42(1): 260-264. https://doi.org/10.3969/j.issn.1000-3428.2016.01.046The macroblocks of stereoscopic video in different regions have different importance,some macroblock losses will seriously affect the quality of the reconstructed video.For such a problem,a macroblock importance distinguishing model of stereoscopic video is presented,which is combined with image saliency detection.At first,saliency of video frame is calculated by image saliency detection algorithm,then the importance of macroblocks of video frame is estimated according to motion information.Finally,the effect on macroblock importance of depth information is considered,and the macroblock importance model of stereoscopic video is constructed.The simulation of packet loss is conducted on stereoscopic videos of different motion degrees and types.The results demonstrate that,when packet loss is instructed by the macroblock model,the subjective and objective quality of decoded videos are improved compared with random packet loss.
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Computer Engineering. 2016, 42(1): 265-271. https://doi.org/10.3969/j.issn.1000-3428.2016.01.047Outdoor images are often severely degraded due to atmosphere scattering of suspended particles on the condition of haze and foggy weather.In order to solve the problem,this paper proposes a single image adaptive defogging algorithm.Transmission is estimated indirectly by the method of accurate atmospheric veil through guided filtering on the basis of analysis of characteristic for atmospheric veil.Transmission of bright areas can be adjusted utilizing adaptive threshold value which obviously reforms the false colors in defogging images.At last,the images are recovered in the way of taking advantage of atmosphere scattering model.Experimental results show that compared with traditional guidance filtering algorithm and selecting stationary threshold value algorithm,the obtained defogging images have clearer nearby view and more natural bright areas,and the computational speed is improved.
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Computer Engineering. 2016, 42(1): 272-277. https://doi.org/10.3969/j.issn.1000-3428.2016.01.048iming at the problem that nonlinear estimation results of Extended Kalman Filter-based Simultaneous Localization and Mapping(EKF-SLAM) algorithm are inconsistent,this paper proposes an Improved Extended Kalman Filter-based Simultaneous Localization and Mapping(IEKF-SLAM) algorithm with polynomial.And on this basis,it designs a tracking and registration algorithm of Augmented Reality(AR) on unknown scene including mapping and updating,tracking and registration two parallel modules.Mapping and updating module uses the IEKF-SLAM algorithm.The tracking and registration module after video frame is captured,camera pose is estimated by constructing a map library.Then video frames feature points are extracted and the feature points are matched to the map library.The pose of the camera is updated.Then virtual objects are rendered and registered.Experimental results show that the consistency of the IEKF-SLAM algorithm is superior to the EKF-SLAM algorithm,and the result of tracking and registration of AR is satisfactory.
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Computer Engineering. 2016, 42(1): 278-281,286. https://doi.org/10.3969/j.issn.1000-3428.2016.01.049In order to detect saliency object accurately in natural scenes,an image saliency detection based on boundary prior in natural scenes is proposed in this paper.The original image is first segmented into a set of superpixels with similar color and texture using simple linear iterative clustering superpixel segmentation algorithm.According to the theory of boundary prior,4 boundary prior saliency maps are calculated separately.It combines them to get a coarse saliency map which separates the background and salient object roughly.The final saliency map which further highlight salient object is generated by regarding the centroid of the boundary prior saliency map as the center of salient object to compute spatial saliency.Simulation result demonstrates that this methor can uniformly highlight saliency object and effectively suppress the background in natural scenes compared with Itti algorithm,contrast based method,graph based method,etc.
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Computer Engineering. 2016, 42(1): 282-286. https://doi.org/10.3969/j.issn.1000-3428.2016.01.050Sequence alignment of large-scale and long sequences is one of the most important and basic issues in bioinformatics.This paper focuses on Burrows-Wheeler Transform(BWT) which is the major index technology in sequence alignment algorithms and proposes a new second-order BWT index concept as well as its implementation.Different from the traditional BWT algorithm while searching with a single character,the algorithm can find two characters at one time.Experimental results show that the second-order BWT index algorithm can reduce the frequency of loop and calculation in sequence alignment algorithm.It can also reduce the alignment algorithm complexity by half and improve the search efficiency,especially for large-scale and long sequence’s index and searching process.
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Computer Engineering. 2016, 42(1): 287-291. https://doi.org/10.3969/j.issn.1000-3428.2016.01.051Considering both of space-based relay satellite and ground-based stations respectively,the measurement and control performance of the launch vehicle is simulated based on Satellite Tool Kit(STK).The establishment of the launching coordinate-system,the utilization of the trajectory and attitude data,the definitions of related vectors and angles,and the setting and measuring of related performance parameters are described.The representative illustration is given,with the analysis and discussion of some simulation results,such as the attaching angles of terminal antennae,the coverage and performance of space and ground integration,etc.It manifests that the STK based simulation,which proved high-speed,high-resolution of computation and operative convenience,is profitable in the fast gross evaluation of rocket performance.
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Computer Engineering. 2016, 42(1): 292-299. https://doi.org/10.3969/j.issn.1000-3428.2016.01.052A mobile business management system is designed,which is based on the problem that existing mobile management weighs too heavily on the results management and cannot master dynamic process.An overall system network scheme that is based on wireless network,Internet and PSTN is presented.With the smart phone used for mobile platform and the Socket,cross-platform communications between the platform of PC and mobile phone are achieved.It also realizes functions such as real-time positioning of field staff,remote dispatching,customer service process management and visual surveillance.Through the test,it improves a very high service efficiency and enterprise mobility in the practical applications.
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Computer Engineering. 2016, 42(1): 300-303. https://doi.org/10.3969/j.issn.1000-3428.2016.01.053In the field of measurement and positioning,establishing ionospheric delay model is an effective means of eliminating the influence of the ionosphere.Previous ionospheric delay model only considers the influence of firstly-order,this can no longer meet the needs of precision measurement and positioning.Using surface fitting method to solve Earth’s magnetic field vector,the results prove that,without loss of accuracy,using surface fitting can achieve the purpose of simplifying calculations and convenient use.The observation equation of Vertical Total Electron Content(VTEC) model is derived by considering the second-order ionospheric effects,establishing the VTEC model by considering the second-order ionospheric effects.Combined with the data of Wuhan tracking station to test the model’s performance,high precision of the model is proved.
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Computer Engineering. 2016, 42(1): 304-310,315. https://doi.org/10.3969/j.issn.1000-3428.2016.01.054In order to control the dip angle and speed of the robot simultaneously on robot modeling,based on the mathematical models of two-wheeled patrol robot,Linear Quadratic Regulator(LQR) controller is designed for the system.The condition for system stability is developed so that the proper control parameters can be chosen to guarantee the whole system stability.In actual application,Kalman filtering algorithm is used to acquire dip angle by fusing data from the accelerometer and the gyroscope.The simulation in Matlab-Simulink platform and real-time control in real robot platform experiments result show that based on Kalman filtering and LQR algorithm,the two-wheeled robot can run erectly at the specified speed and has strong anti-interference performance.
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Computer Engineering. 2016, 42(1): 311-315. https://doi.org/10.3969/j.issn.1000-3428.2016.01.055A sequence classification methodology is proposed based on a conjecture that neighborhood’s similarity results in sequence’s similarity.The constrained Hidden Markov Model(HMM) space defined by sample is transformed to unconstrained HMM space.The neighborhood information is extracted at the standard HMM,and is imported to the SVM.Experimental results show that compared with other classical sequence classification methods,the proposed methodology can indeed greatly improve accuracy or speed.Meanwhile,the results also validate the original conjecture.
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Computer Engineering. 2016, 42(1): 316-321. https://doi.org/2016.01.056
In order to reduce the surrounding rock collapse,flooding and other geological disasters that often happen in subway tunnel construction and to get a clearer understanding about the geological conditions of the surrounding rock in the construction area,this paper adopts a basic quality sub grade of rock mass method based on the weight to classify the surrounding rock,combining C# with the secondary development of ArcEngine to design a system according to the principle of Inverse Distance Weighted(IDW) to estimate the grade and realize the 3D hierarchical display and rendering of the surrounding rock based on the existing drilling data.At the same time,this system can be used to verify the accuracy of the sub grade method.Experimental results indicate that the basic quality sub grade of surrounding rock method based on the weight is more precisely in the classification of tunnel surrounding rock and has better practicability.The inverse error of system estimation in the classification of the surrounding rock is 8.82%,compared with the excavation revealed information,the difference is 13%,the 3D hierarchical display and rendering of the surrounding rock is closer to the actual situation,which can provide a reference for the subway tunnel construction.
2024
Volume 50 No 3
Volume 50 No 3
(Started in 1975, Monthly)
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428