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Walking control and stability analysis of flexible biped robot with variable length legs
LIAO Fakang, ZHOU Yali, ZHANG Qizhi
Journal of Computer Applications    2023, 43 (1): 312-320.   DOI: 10.11772/j.issn.1001-9081.2021111953
Abstract361)   HTML5)    PDF (4678KB)(106)       Save
Aiming at the problem that the traditional biped robot model lacks the feet mass and the torso, a flexible biped robot model considering the influence of swing leg dynamics and torso was proposed, and its walking control and stability were studied. Firstly, the dynamics model of the system was established and the dynamics equation was deduced by the Euler-Lagrange method. At the same time, based on the Spring-Loaded Inverted Pendulum (SLIP) model, by adding rigid torso, foot mass, and adopting telescopic legs of variable length, the influence of the torso and the dynamics of swing legs on the gait of the robot was fully considered. Then, the feedback linearization controller based on variable length legs was designed to track the target trajectory and regulate the attitudes of the swing legs and the torso. Finally, the Newton-Raphson iteration method and Poincaré map were adopted to analyze the fixed point and orbital stability conditions of the robot. Simulation analysis was carried out based on theoretical analysis. Simulation results show that the proposed controller can realize the robot’s periodic walking and has good robustness to the external interference. And the moduli of all eigenvalues of the Jacobian matrix are less than 1, forming a stable limit cycle, which proves that the system has orbital stability.
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Improved feature selection and classification algorithm for gene expression programming based on layer distance
ZHAN Hang, HE Lang, HUANG Zhangcan, LI Huafeng, ZHANG Qiang, TAN Qing
Journal of Computer Applications    2021, 41 (9): 2658-2667.   DOI: 10.11772/j.issn.1001-9081.2020111801
Abstract318)      PDF (1220KB)(352)       Save
Concerning the problem that the interpretable mapping relationship between data features and data categories do not be revealed by general feature selection algorithms. on the basis of Gene Expression Programming (GEP),by introducing the initialization methods, mutation strategies and fitness evaluation methods,an improved Feature Selection classification algorithm based on Layer Distance for GEP(FSLDGEP) was proposed. Firstly,the selection probability was defined to initialize the individuals in the population directionally, so as to increase the number of effective individuals in the population. Secondly, the layer neighborhood of the individual was proposed, so that each individual in the population would mutate based on its layer neighborhood, and the blind and unguided problem in the process of mutation was solved。Finally, the dimension reduction rate and classification accuracy were combined as the fitness value of the individual, which changed the population evolutionary mode of single optimization goal and balanced the relationship between the above two. The 5-fold and 10-fold verifications were performed on 7 datasets, the functional mapping relationship between data features and their categories was given by the proposed algorithm, and the obtained mapping function was used for data classification. Compared with Feature Selection based on Forest Optimization Algorithm (FSFOA), feature evaluation and selection based on Neighborhood Soft Margin (NSM), Feature Selection based on Neighborhood Effective Information Ratio (FS-NEIR)and other comparison algorithms, the proposed algorithm has obtained the best results of the dimension reduction rate on Hepatitis, Wisconsin Prognostic Breast Cancer (WPBC), Sonar and Wisconsin Diagnostic Breast Cancer (WDBC) datasets, and has the best average classification accuracy on Hepatitis, Ionosphere, Musk1, WPBC, Heart-Statlog and WDBC datasets. Experimental results shows that the feasibility, effectiveness and superiority of the proposed algorithm in feature selection and classification are verified.
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Time of arrival positioning based on time reversal
ZHANG Qilin, LI Fangwei, WANG Mingyue
Journal of Computer Applications    2021, 41 (3): 820-824.   DOI: 10.11772/j.issn.1001-9081.2020060976
Abstract476)      PDF (950KB)(931)       Save
It is difficult for traditional algorithms to accurately find out the first direct path in indoor Ultra Wide Band (UWB) Time Of Arrival (TOA) positioning system, resulting in low positioning accuracy. In order to solve the problem, a TOA indoor UWB positioning algorithm based on Time Reversal (TR) was proposed. Firstly, the spatial-temporal focusing characteristic of TR processing was used to determine the first direct path, so as to estimate the TOA of this path. Then, the Weighted Least Squares (WLS) positioning algorithm was used to assign the corresponding weights to different estimation components for improving the positioning accuracy. The simulation results show that, compared with the traditional TOA positioning, the proposed scheme has the Root Mean Square Error (RMSE) reduced by 28.6% under the low signal-to-noise ratio condition. It can be seen that the proposed scheme improves the system positioning accuracy significantly.
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Improved pyramid evolution strategy for solving split delivery vehicle routing problem
LI Huafeng, HUANG Zhangcan, ZHANG Qiang, ZHAN Hang, TAN Qing
Journal of Computer Applications    2021, 41 (1): 300-306.   DOI: 10.11772/j.issn.1001-9081.2020050615
Abstract517)      PDF (948KB)(563)       Save
To solve the Split Delivery Vehicle Routing Problem (SDVRP) more reasonably, overcome the shortcoming that the traditional two-stage solution method of first route and then optimization is easy to fall into local optimization, and handle the problem that the intelligent optimization algorithm fails to integrate competition and cooperation organically in the optimization stage, an Improved Pyramid Evolution Strategy (IPES) was proposed with the shortest delivery path and the least delivery vehicles as the optimization objectives. Firstly, based on the pyramid, the encoding and decoding methods and hierarchical cooperation strategy were proposed to solve SDVRP. Secondly, according to the characteristics such as the random of genetic algorithm, high parallelism of "survival of the fittest" and self-adaption, as well as the different labor division of different layers of pyramid structure, an adaptive neighborhood operator suitable for SDVRP was designed to make the algorithm converge fast to the optimum. Finally, the optimal solution was obtained. Compared with the piecewise solving algorithm, clustering algorithm, particle swarm algorithm, artificial bee colony algorithm, taboo search algorithm,the results of four simulation experiments show that, when solving the optimal path of each case, the proposed IPES has the solution accuracy improved by at least 0.92%, 0.35%, 3.07%, 9.40% respectively, which verifies the good performance of IPES in solving SDVRP.
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Entity relation extraction method for guidelines of cardiovascular disease based on bidirectional encoder representation from transformers
WU Xiaoping, ZHANG Qiang, ZHAO Fang, JIAO Lin
Journal of Computer Applications    2021, 41 (1): 145-149.   DOI: 10.11772/j.issn.1001-9081.2020061008
Abstract876)      PDF (823KB)(1158)       Save
Entity relation extraction is a critical basic step of question answering, knowledge graph construction and information extraction in the medical field. In view of the fact that there is no open dataset available in the process of building knowledge graph specialized for cardiovascular disease, a professional training set for entity relation extraction of specialized cardiovascular disease knowledge graph was constructed by collecting some medical guidelines for cardiovascular disease and performing the corresponding professional labeling of the categories of entities and relations. Based on this dataset, firstly, Bidirectional Encoder Representation from Transformers and Convolutional Neural Network (BERT-CNN) model was proposed to realize the relation extraction in Chinese corpus. Then, the improved Bidirectional Encoder Representation from Transformers and Convolutional Neural Networks based on whole word mask (BERT(wwm)-CNN) model was proposed to improve the performance of relation extraction in Chinese corpus, according to the fact that word instead of character is the fundamental unit in Chinese. Experimental results show that, the improved BERT(wwm)-CNN model has the accuracy of 0.85, the recall of 0.80 and the F 1 value of 0.83 on the constructed relation extraction dataset, which are better than those of the comparison models, Bidirectional Encoder Representation from Transformers and Long Short Term Memory (BERT-LSTM) and BERT-CNN, verifying the superiority of the improved BERT(wwm)-CNN.
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Application of deep learning to 3D model reconstruction of single image
ZHANG Hao, ZHANG Qiang, SHAO Siyu, DING Haibin
Journal of Computer Applications    2020, 40 (8): 2351-2357.   DOI: 10.11772/j.issn.1001-9081.2020010070
Abstract679)      PDF (1711KB)(476)       Save
To solve the problem that the reconstructed 3D model of a single image has high uncertainty, a network model based on depth image estimation, spherical projection mapping and 3D generative adversarial network was proposed. Firstly, the depth image of the input image was obtained by the depth estimator, which was helpful for the further analysis of the image. Secondly, the obtained depth image was converted into a 3D model by spherical projection mapping. Finally, 3D generative adversarial network was utilized to judge the authenticity of the reconstructed 3D model, so as to obtain 3D model closer to reality. In the comparison experiments with LVP algorithm which learning view priors for 3D reconstruction, the proposed model has the Intersection-over-Union (IoU) increased by 20.1% and the Charmfer Distance (CD) decreased by 13.2%. Theoretical analysis and simulation results show that the proposed model has good generalization ability in the 3D model reconstruction of a single image.
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MinRank analysis of cubic multivariate public key cryptosystem
ZHANG Qi, NIE Xuyun
Journal of Computer Applications    2020, 40 (7): 1965-1969.   DOI: 10.11772/j.issn.1001-9081.2019112052
Abstract358)      PDF (661KB)(315)       Save
The cubic cryptosystem is the improvement of the classical multivariable cryptosystem Square. By increasing the degree of central mapping from square mapping to cubic mapping, the public key polynomial was promoted from quadratic to cubic in order to resist the MinRank attack against the quadratic multivariable public key cryptosystem. Aiming at this system, a MinRank attack combining with difference was proposed to recover its private key. Firstly, the central mapping difference of the system was analyzed, and its rank was determined according to the structure after difference. Then, the difference of the public key was solved and the coefficient matrices of the quadratic term were extracted. After that, a MinRank problem was constructed by the coefficient matrix and the determined rank. Finally, the extended Kipnis-Shamir method was combined to solve the problem. The experimental results show that the private key of cubic cryptosystem can be recovered by using MinRank attack.
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Modeling and memetic algorithm for vehicle routing problem with simultaneous pickup-delivery and time windows
ZHANG Qinghua, WU Guangpu
Journal of Computer Applications    2020, 40 (4): 1097-1103.   DOI: 10.11772/j.issn.1001-9081.2019081355
Abstract789)      PDF (1187KB)(679)       Save
In order to solve the Vehicle Routing Problem with Simultaneous Pickup-Delivery and Time Windows (VRPSPDTW)in the context of reverse logistics,the corresponding vehicle routing problem model was established according to the actual situation and solved by memetic algorithm. In the process of solving the model,the Guided Ejection Search (GES)was used to generate the initial population. In the process of population evolution,the Edge Assembly Crossover (EAX)method was used to generate the offspring,and in order to improve the quality of solutions and the search efficiency of algorithms,multiple neighborhood structures were used to repair and educate the offspring. The performance of memetic algorithm was tested and compared with Genetic Algorithm (GA),parallel-Simulate Annealing algorithm (p-SA) and Discrete Cuckoo Search(DCS)algorithm on Wang and Chen test dataset. Experimental results show that the proposed algorithm obtains the current optimal solutions when solving all small-scale examples;the algorithm updates or achieves current optimal solutions on 70% examples when solving the standard-scale examples,and the obtained optimal solution has more than 5% improvement compared with the current optimal solution,fully verifying the good performance of the algorithm for solving VRPSPDTW.
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Civil aviation engine module maintenance level decision-making and cost optimization based on annealing frog leaping particle swarm algorithm
ZHANG Qing, ZHENG Yan
Journal of Computer Applications    2020, 40 (12): 3541-3549.   DOI: 10.11772/j.issn.1001-9081.2020040565
Abstract322)      PDF (1129KB)(430)       Save
For the problems of scope decision-making of maintenance for civil aviation engine module and cost optimization of full-life maintenance, the engine module maintenance level decision-making and cost optimization model based on annealing frog leaping particle swarm optimization algorithm with return time interval as variable was proposed. Firstly, according to the maintenance logic diagram for each module in maintenance instruction manual and the replacement situation of life-limited parts, the engine shop visit cost function was built. Secondly, by using the annealing frog leaping particle swarm optimization algorithm, the shop visit costs of different return times and the maintenance level for each module in full life time were determined. Finally, based on examples, the proposed algorithm was compared with the basic particle swarm optimization algorithm, annealing particle swarm optimization algorithm and shuffled frog leaping optimization algorithm, and the influence of different return times on maintenance cost and reliability was analyzed. Experimental results indicate that, when the engine has five shop visits in its full life time, the average cost obtained using annealing frog leaping particle swarm optimization algorithm was 322.479 1 $/flight hour, which was the optimum value compared with those of the other three optimization algorithms. The proposed algorithm can facilitate the shop visit decision-making of airlines and overhaul companies.
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Design and implementation of electronic file circulation based on blockchain
HAN Yanyan, ZHANG Qi, YAN Xiaoxuan, LIU Peihe, XU Pengge
Journal of Computer Applications    2020, 40 (11): 3357-3365.   DOI: 10.11772/j.issn.1001-9081.2020040526
Abstract542)      PDF (2881KB)(544)       Save
Aiming at the problems that there is no unified registration of files, the whereabouts of files are not tracked, and the process of circulation is not standardized in the circulation of electronic files under the Internet ecology, a blockchain-based electronic file circulation scheme was proposed. Firstly, the design goals and design architecture of the electronic file circulation system based on blockchain were proposed using the multi-centralized system of the consortium blockchain in the blockchain. Secondly, blockchain-based electronic file circulation system was implemented by using a cloud storage platform to upload files for electronic file storage and adding time-stamps of the ownership transfer data of files to make the circulation process continuous, relevant, traceable, honest and credible. The data synchronization and tracing of the blockchain-based electronic file circulation system was achieved through using database calls to realize the data access. Finally, a smart contract for electronic file ownership transfer and query to verify and protect the contents of the files by reading the file identification. The security analysis and performance tests show that compared to the original one, the proposed scheme is more secure and enhances the credibility of the circulation information, at the same time, the shorter execution time of the smart contract makes the system have better reliability and traceability.
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Two-input stream deep deconvolution neural network for interpolation and recognition
ZHANG Qiang, YANG Jian, FU Lizhen
Journal of Computer Applications    2019, 39 (8): 2271-2275.   DOI: 10.11772/j.issn.1001-9081.2018122555
Abstract462)      PDF (822KB)(280)       Save
It is impractical to have a large size of training dataset in real work for neural network training, so a two-input stream generative neural network which can generate a new image with the given parameters was proposed, hence to augment the training dataset. The framework of the proposed neural network consists of a two-input steam convolution network and a deconvolution network. The two-input steam network has two convolution networks to extract features, and the deconvolution network is connected to the end. Two images with different angle were input into the convolution network to get high-level description, then an interpolation target image with a new perspectives was generated by using the deconvolution network with the above high-level description and set parameters. The experiment results on ShapeNetCore show that on the same dataset, the recognition rate of the proposed network has increased by 20% than the common network framework. This method can enlarge the size of the training dataset and is useful for multi-angle recognition.
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Weighted reviewer graph based spammer group detection and characteristic analysis
ZHANG Qi, JI Shujuan, FU Qiang, ZHANG Chunjin
Journal of Computer Applications    2019, 39 (6): 1595-1600.   DOI: 10.11772/j.issn.1001-9081.2018122611
Abstract458)      PDF (949KB)(341)       Save
Concerning the problem that how to detect spammer groups writing fake reviews on the e-commerce platforms, a Weighted reviewer Graph based Spammer group detection Algorithm (WGSA) was proposed. Firstly, a weighted reviewer graph was built based on the co-reviewing feature with the weight calculated by a series of group spam indicators. Then, a threshold was set for the edge weight to filter the suspicious subgraphs. Finally, considering the community structure of the graph, the community discovery algorithm was used to generate the spammer groups. Compared with K-Means clustering algorithm ( KMeans), Density-Based spatial clustering of applications with noise (DBscan) and hierarchical clustering algorithm on the large dataset Yelp, the accuracy of WGSA is higher. The characteristics and distinction of the detected spammer groups were also analyzed, which show that spammer groups with different activeness have different harm. The high-active group is more harmful and should be concerned more.
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Rate smooth switching algorithm based on DASH standard
HUANG Sheng, FU Yuanpeng, ZHANG Qianyun
Journal of Computer Applications    2019, 39 (4): 1122-1126.   DOI: 10.11772/j.issn.1001-9081.2018091933
Abstract431)      PDF (887KB)(370)       Save
Concerning the fact that the existing rate adaptation algorithms based on Dynamic Adaptive Streaming over HTTP (DASH) have frequent bitrate switching and low average bitrate in wireless network, a Rate Smooth Switching (RSS) algorithm based on DASH standard was proposed. Firstly, a sliding window was used by the bandwidth detection mechanism of the algorithm to sample the download speed of historical segments to calculate the bandwidth offset coefficient, the fluctuation of the bandwidth was initially determined according to the value of offset coefficient, and the situation of the fluctuation was further determined whether there was a consistent variation trend, thereby distinguishing continuous variation and short-term jitter of the bandwidth, and the bandwidth prediction value corresponding to each circumstance was calculated. Secondly, with bandwidth fluctuation, buffer occupancy and variation, bandwidth prediction value considered, the rate decision model of the algorithm adopted Fast Buffering (FB), Slow Switching (SS), Fast Rising (FR), Limited Declining (LD), Stable Holding (SH) strategies and sleeping mechanism to dynamically control the video bitrate selection process. The experimental results show that compared with fuzzy-based DASH rate adaptation algorithm and modulated throughput driven rate adaptation algorithm, the proposed algorithm can not only increase the bitrate to optimum level in the shortest time at the beginning of video playback to improve the average bitrate, but also minimize the number of bitrates' switching in the case of sudden change and frequent fluctuation of bandwidth, thus obtaining a good quality of experience for wireless video users.
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Retrieval matching question and answer method based on improved CLSM with attention mechanism
YU Chongchong, CAO Shuai, PAN Bo, ZHANG Qingchuan, XU Shixuan
Journal of Computer Applications    2019, 39 (4): 972-976.   DOI: 10.11772/j.issn.1001-9081.2018081691
Abstract470)      PDF (752KB)(368)       Save
Focusing on the problem that the Retrieval Matching Question and Answer (RMQA) model has weak adaptability to Chinese corpus and the neglection of semantic information of the sentence, a Chinese text semantic matching model based on Convolutional neural network Latent Semantic Model (CLSM) was proposed. Firstly, the word- N-gram layer and letter- N-gram layer of CLSM were removed to enhance the adaptability of the model to Chinese corpus. Secondly, with the focus on vector information of input Chinese words, an entity attention layer model was established based on the attention mechanism algorithm to strengthen the weight information of the core words in sentence. Finally, Convolutional Neural Network (CNN) was used to capture the input sentence context structure information effectively and the pool layer was used to reduce the dimension of semantic information. In the experiments based on a medical question and answer dataset, compared with the traditional semantic models, traditional translation models and deep neural network models, the proposed model has 4-10 percentage points improvement in Normalized Discount Cumulative Gain (NDCG).
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Security analysis and evaluation of representational state transfer based on attack graph
ZHANG Youjie, ZHANG Qingping, WU wei, SHI Zhe
Journal of Computer Applications    2018, 38 (6): 1653-1657.   DOI: 10.11772/j.issn.1001-9081.2017112756
Abstract542)      PDF (800KB)(458)       Save
The security mechanism of REpresentational State Transfer (REST) architecture is not perfect. In order to solve the problem, the security analysis and evaluation of REST architecture based on attack graph was proposed, and the security quantitative evaluation of REST architecture was realized by using attack graph. Firstly, the possible attack of REST architecture was predicted, the REST architecture attack graph model was constructed accordingly, and the attack probability parameter and attack realization parameter were calculated. Then, according to the attack state and attack behavior of attack graph, the security protection measures were proposed. In view of the above, the REST architecture attack graph model was reconstructed, and the attack probability parameter and attack realization parameter were recalculated too. By comparison, after the adoption of security protection measures, the attack possibility parameter has been reduced to about 1/10, and the attack realization parameter has been reduced to about 1/86. The comparison results show that the constructed attack graph can effectively and quantitatively evaluate the security performance of REST architecture.
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Multi-source point of interest fusion algorithm based on distance and category
XU Shuang, ZHANG Qian, LI Yan, LIU Jiayong
Journal of Computer Applications    2018, 38 (5): 1334-1338.   DOI: 10.11772/j.issn.1001-9081.2017102504
Abstract622)      PDF (748KB)(501)       Save
In order to achieve effective integration and accurate fusion of multi-source Point of Interest (POI) data, a Mutually-Nearest Method considering Distance and Category (MNMDC) was proposed. Firstly, for spatial attributes, standardized weight algorithm was used to calculate the spatial similarity of the object to be fused, and the fusion set was obtained. Secondly, for non-spatial attributes, Jaro-Winkle algorithm was used to eliminate some objects with consistent categories by a low threshold, and exclude some objects with inconsistent categories by a high threshold. Finally, non-spatial Jaro-Winkle algorithm with distance constraint, category consistency constraint and high threshold was used to find out the missing objects in the spatial algorithm. The experimental results show that the average accuracy reaches 93.3%, compared with Combined Normal Weight and Title-similatity algorithm (COM-NWT) and the grid correction methods, the accuracy of MNMDC method in seven different groups of coincidence degree data, the average accuracy increases by 2.7 percentage points and 1.6 percentage points, the average recall increases by 2.3 and 1.4 percentage points. The MNMDC method allows more accurate fusion of POI data during actual fusion.
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Adaptive differential evolution algorithm based on multiple mutation strategies
ZHANG Qiang, ZOU Dexuan, GENG Na, SHEN Xin
Journal of Computer Applications    2018, 38 (10): 2812-2821.   DOI: 10.11772/j.issn.1001-9081.2018030684
Abstract340)      PDF (1379KB)(399)       Save
In order to overcome the disadvantages of Differential Evolution (DE) algorithm such as low optimization accuracy, slow convergence and poor stability, an Adaptive Differential Evolution algorithm based on Multi-Mutation strategy (ADE-MM) was proposed. Firstly, two disturbance thresholds with learning functions were used in the selection of three mutation strategies to increase the diversity of the population and expand the search scope. Then, according to the successful parameters of the last iteration, the current parameters were adjusted adaptively to improve the search accuracy and speed. Finally, vector particle pool method and central particle method were used to generate new vector particles to further improve the search effect. Tests were performed on 8 functions for 5 comparison algorithms (Random Mutation Differential Evolution (RMDE), Cross-Population Differential Evolution algorithm based on Opposition-based Learning (OLCPDE), Adaptive Differential Evolution with Optional External Archive (JADE), Self-adaptive Differential Evolution (SaDE), Modified Differential Evolution with p-best Crossover (MDE_pBX)), and each example was independently performed 30 times. The ADE-MM algorithm achieves a complete victory in the comparison of mean and variance, 5 independent wins and 3 tie wins are achieved in the 30-dimensional case; 6 independent wins and 2 tie wins are obtained in the 50-dimensional case; in 100-dimensional case, all are won independently. At the same time, in the Wilcoxon rank sum test, winning rate and time-consuming analysis, the ADE-MM algorithm also achieves excellent performance. The results show that ADE-MM algorithm has stronger global search ability, convergence and stability than other five comparison algorithms.
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Prediction algorithm of dynamic trajectory based on weighted grey model(1,1)
JIANG Yixian, ZHANG Qishan
Journal of Computer Applications    2016, 36 (5): 1336-1340.   DOI: 10.11772/j.issn.1001-9081.2016.05.1336
Abstract376)      PDF (685KB)(460)       Save
The noise assumption and motion assumption of trajectory should be demanded in dynamic trajectory prediction based on Kalman filter. In order to eliminate this insufficiency, the metabolism GM(1,1) model was introduced in dynamic trajectory prediction. Thus a prediction algorithm based on weighted grey GM(1,1) model (TR_GM_PR algorithm)was presented. Firstly, sub-trajectories with different length before forecasting point were cut out in order, then the relative fitting errors and predicted values of sub-trajectories were calculated using grey GM(1,1) model. Secondly, the normalization processing of relative fitting errors was carried out, and the weights of predicted values were set according to the result. Finally, using the linear combination of predicted values and their corresponding weights, the running tendency of trajectory in future was predicted. Experiments were conducted with the Atlantic weather Hurricane data from 2000 to 2008. Compared with hurricane trajectory prediction method with pattern matching, TR_GM_PR algorithm improves the prediction accuracy ratio of 6 hours by 2.6056 percentage points to 67.6056%. The experimental results show that TR_GM_PR algorithm is suitable for short-term trajectory prediction. In addition, the new algorithm has simple calculation and high real-time performance, and can effectively improve the prediction accuracy of dynamic trajectory.
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Parallel particle swarm optimization algorithm in multicore computing environment
HE Li, LIU Xiaodong, LI Songyang, ZHANG Qian
Journal of Computer Applications    2015, 35 (9): 2482-2485.   DOI: 10.11772/j.issn.1001-9081.2015.09.2482
Abstract540)      PDF (739KB)(431)       Save
Aiming at the problem that serial Particle Swarm Optimization (PSO) algorithms are time-consuming to deal with big tasks, a novel shared parallel PSO (Shared-PSO) algorithm was proposed. The multi-core processing power was used to reduce time to get resolution. In order to facilitate communication of particles, a shared area was set up and a random strategy was applied to switch particles. Several serial PSO algorithms could be permitted to update particle information because of the universality of its algorithm flow. Shared-PSO was applied on the standard optimization test set CEC (Congress on Evolutionary Computation) 2014. The experiment results show that the execution time of Shared-PSO is a quarter of the serial PSO's. The proposed algorithm can effectively improve the execution efficiency of serial PSO, and expand applied range of PSO.
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Nash bargaining based resource allocation in peer-to-peer network
ZHANG Qingfeng, WANG Sheng, LIAO Dan
Journal of Computer Applications    2015, 35 (9): 2424-2429.   DOI: 10.11772/j.issn.1001-9081.2015.09.2424
Abstract527)      PDF (994KB)(435)       Save
To effectively overcome the free-rider problem existing in Peer-to-Peer (P2P) network, this paper presented resource allocation scheme based on Nash bargaining which guarantees the minimum Quality of Service (QoS). Firstly, the article built the system model of the minimum QoS, analysis indicated that the cooperative peer' bargaining power is positively related to the maximum contribution ability but the non-cooperative peer' bargaining power is negative related to the maximum contribution ability, so, the cooperative peers can obtain more resources than non-cooperative peers; secondly, the article demonstrated that the cooperative peer who has larger relative bargaining power could obtain more resources than the others. Lastly, simulations show that to guarantee the peers receiving the minimum QoS, the cooperation peers resource allocation related to the initial resource allocation and the Nash bargaining power and other factors; the initial resource allocation is positively related to the maximum contribute ability of the cooperation peers, which reduces when the number of peers increases; the bargaining power decreases when the number of peers increases and resource allocation increases when the bargaining power increases. This resource allocation mechanism was compared with the classical average resource allocation mechanism which also guarantees the fairness, the cooperators can obtain more resources. The simulation results verified that the greater the bargaining power of nodes, the more resources to obtain within the minimum QoS.
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Open robot Agent: construction of host SoftMan
WU Danfeng, ZENG Guangping, XIAO Chao'en, ZHANG Qingchuan
Journal of Computer Applications    2015, 35 (6): 1766-1772.   DOI: 10.11772/j.issn.1001-9081.2015.06.1766
Abstract583)      PDF (976KB)(581)       Save

To solve the problems of updating, modifying, upgrading and maintaining the function of robot by offline and static method, SoftMan was introduced for robot platform, and the architecture of robot system, whose managing center is host SoftMan, was built. The host SoftMan was mainly researched. Firstly, the architecture of host SoftMan was constructed. Then the descriptive unification model of knowledge and behavior of host SoftMan was put forward, the knowledge model was constructed and implemented based on data structure, and the design specifications and reference realization of the algorithm were given for its main service behaviors. Finally, the robot system was unified with the SoftMan system. Through the test, the function of robot was successfully replaced online and dynamically, verifying the correctness and feasibility of the method of designing and implementing the host SoftMan.

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Double subgroups fruit fly optimization algorithm with characteristics of Levy flight
ZHANG Qiantu, FANG Liqing, ZHAO Yulong
Journal of Computer Applications    2015, 35 (5): 1348-1352.   DOI: 10.11772/j.issn.1001-9081.2015.05.1348
Abstract586)      PDF (713KB)(904)       Save

In order to overcome the problems of low convergence precision and easily relapsing into local optimum in Fruit fly Optimization Algorithm (FOA), by introducing the Levy flight strategy into the FOA, an improved FOA called double subgroups FOA with the characteristics of Levy flight (LFOA) was proposed. Firstly, the fruit fly group was dynamically divided into two subgroups (advanced subgroup and drawback subgroup) whose centers separately were the best individual and the worst individual in contemporary group according to its own evolutionary level. Secondly, a global search was made for drawback subgroup with the guidance of the best individual, and a finely local search was made for advanced subgroup by doing Levy flight around the best individual, so that not only both the global and local search ability balanced, but also the occasionally long distance jump of Levy flight could be used to help the fruit fly jump out of local optimum. Finally, two subgroups exchange information by updating the overall optimum and recombining the subgroups. The experiment results of 6 typical functions show that the new method has the advantages of better global searching ability, faster convergence and more precise convergence.

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Authentication protocol based on pseudo-random function for mobile radio frequency identification
ZHANG Qi, LIANG Xiangqian, WEI Shumin
Journal of Computer Applications    2015, 35 (4): 977-980.   DOI: 10.11772/j.issn.1001-9081.2015.04.0977
Abstract602)      PDF (562KB)(690)       Save

To solve the security problems between the reader and the server of mobile Radio Frequency IDentification (RFID) caused by wireless transmission, a two-way authentication protocol based on pseudo-random function was provided. It satisfied the EPC Class-1 Generation-2 industry standards, and mutual certifications between tags, readers and servers were achieved. The security of this protocol was also proved by using GNY logic. It can effectively resist track, replay and synchronization attack etc.; simultaneously, its main calculations are transferred to the server, thereby reducing the calculations and cost of the tag.

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Image multi-scale recognition method based on computer vision
ZHANG Yupu, YANG Qi, ZHANG Qi
Journal of Computer Applications    2015, 35 (2): 502-505.   DOI: 10.11772/j.issn.1001-9081.2015.02.0502
Abstract653)      PDF (726KB)(697)       Save

Focusing on the issues of size-varying and angle-varying of the images, and low recognition rate and poor robustness in image recognition, a morphological image recognition method was proposed. Firstly, image was centralized and normalized, and the silhouettes of image was converted into binary image. Secondly, varable circles were used to extract morphological features of image, and a fan-shaped area feature vector was established. Finally, multi-scale analysis method was applied to image recognition and image angle analysis. Compared with traditional method in the conditions such as angle independence, proportion independence and profile robustness, the experimental results show that the proposed method has higher recognition rate, and can analyze the angle difference between the images. The method is robust to noise, and can significantly reduce the influence of different image scale and rotation angle on image recognition.

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Fast calculation method of multivariable control for reheat steam temperature based on Smith control and predictive functional control
WANG Fuqiang, LI Xiaoli, ZHANG Qiusheng, ZHANG Jinying
Journal of Computer Applications    2015, 35 (12): 3597-3601.   DOI: 10.11772/j.issn.1001-9081.2015.12.3597
Abstract451)      PDF (700KB)(351)       Save
The reheat steam temperature control system has the problems of multivariable control, difficult control, and so on. In order to solve the problems, a fast calculation method of multivariable control for reheat steam temperature was proposed,which was based on Smith control method and Predictive Functional Control (PFC) method. First of all, the reheat steam temperature multivariable control system was decomposed into three single-variable control systems. In every single-variable control system, the other two control volumes were taken as the interference terms. Secondly, according to Smith control idea, every single-variable control system was designed. Finally, on the basis of improving the performance index of the predictive functional control, three single-variable control systems were considered synthetically to realize the reheat steam temperature control. The simulation results of reheat steam temperature control show that with less parameters and explicit physical meaning, the proposed method is about 50 times as fast as the traditional predictive control with constraint conditions. The experimental results show that the proposed algorithm can effectively improve the quality of the reheat steam temperature control in the field.
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Detecting community in bipartite network based on cluster analysis
ZHANG Qiangqiang, HUANG Tinglei, ZHANG Yinming
Journal of Computer Applications    2015, 35 (12): 3511-3514.   DOI: 10.11772/j.issn.1001-9081.2015.12.3511
Abstract655)      PDF (620KB)(434)       Save
Concerning the problems of the low accuracy of community detection in bipartite network and the strong dependence on additional parameters, depending on the original network topology, based on the idea of spectral clustering algorithm, a new community algorithm was proposed. The proposed algorithm mined community by mapping a bipartite network to a single network, substituted resource distribution matrix for traditional similarity matrix, effectively guaranteed the information of the original network, improved the input of spectral clustering algorithm and the accuracy of community detection. The modularity function was applied to clustering analysis, and the modularity was used to measure the quality of community mining, effectively solved the problem of automatically determining the clustering number. The experimental results on the actual network and artificial network show that, compared with ant colony optimization algorithm, edge clustering coefficient algorithm etc., the proposed algorithm can not only accurately identify the number of the communities of the bipartite network, but also obtain higher quality of community partitioning without previously known parameters. The proposed algorithm can be applied to the deep understanding of bipartite network, such as recommendation and influence analysis.
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Private cloud platform design based on virtualization technology
ZHANG Qian, CHEN Chaogen, LIANG Hong
Journal of Computer Applications    2015, 35 (11): 3063-3069.   DOI: 10.11772/j.issn.1001-9081.2015.11.3063
Abstract691)      PDF (1140KB)(840)       Save
Combined with virtualization technology, a realization scheme of private cloud platform based on multi-framework technology was put forward in order to improve hardware utilization of distributed cluster system and avoid the economic loss caused by the idle equipment. This scheme met the demand for resource allocation, dynamic allocation and dynamic migration, thus the bottom hardware was integrated. Aiming at unbalanced loading in the traditional virtual machine deployment method, the virtual machine deployment mechanism based on dynamic deployment allocation was proposed. According to the characteristics of virtual machine resources and the load of the current physical nodes, dynamic deployment of virtual machine was carried out. At last, private cloud computing platform with strong flexibility and good scalable performance was realized, which had been tested by Fourier finite difference pre-stack depth migration in oil exploration. The results proved the feasibility and effectiveness of the private cloud platform. By deployment test on virtual machine, the results show that the dynamic allocation decision can be used to deploy a large number of virtual machines, and keep good load balancing of private cloud platform at the same time.
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Virtual reality display model based on human vision
XU Yujie, GUAN Huichao, ZHANG Zongwei, GUO Qing, ZHANG Qing
Journal of Computer Applications    2015, 35 (10): 2939-2944.   DOI: 10.11772/j.issn.1001-9081.2015.10.2939
Abstract476)      PDF (790KB)(660)       Save
Aiming at the problem that the current display module could not provide a perfect stereo vision on the principle of human visual system, a solution of Virtual Reality (VR) stereo vision was proposed based on the oblique crossing frustum camera. Firstly, by studying the ken model and the theory of accessing to the depth data by eyes, a mathematical model of eyes parallex was built. Secondly, the industrial engine 3DVIA Studio was used as the simulation platform, which relied on the VSL programming language to screen. The relationship of child and parent was set up and the module of visual interaction was designed to construct the stereo camera. Then, the point cloud model was developed to quantize the stereo sense. The advantages and disadvantages of each model were analyzed based on the characteristics of depth display and distortion, and all models were optimized step by step. Center axis parallel normal frustum camera model and normal frustum model whose center axis crossed at the viewing distance were developed, the frustum of camera was optimized to develop a VR camera model of oblique crossing frustum. At last, using 3DVIA Studio as the experiment platform, specific data were substituted on it to do projective transformation. The result shows that the proposed camera model of oblique crossing frustum eliminates the distortion guarantees the depth information display effection, and provides an excellent effect of vision.
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Framework of serial multimodal biometrics with parallel fusion
LI Haixia, ZHANG Qing
Journal of Computer Applications    2015, 35 (10): 2789-2792.   DOI: 10.11772/j.issn.1001-9081.2015.10.2789
Abstract515)      PDF (801KB)(496)       Save
In the multimodal biometric system, the parallel fusion mode has more advantages than the serial fusion mode in convenience and efficiency. Based on current works on serial multimodal biometric system, a framework combined with parallel fusion mode and serial fusion mode was proposed. In the framework, the weighted score level fusion algorithm using biological features of gait, face and finger was proposed at first;then semi-supervised learning techniques were used to improve the performance of weak traits in the system, and the simultaneous upgrade of user convenience and recognition accuracy was achieved. Analysis and experimental result indicate that the performance of the weak classifier can be improved by online learning, the convenience and recognition accuracy are successfully promoted in this framework.
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Backward recovery of transient fault in multi-cross channel model
MA Manfu YAO Jun ZHANG Qiang JIA Yongxin
Journal of Computer Applications    2014, 34 (9): 2734-2737.   DOI: 10.11772/j.issn.1001-9081.2014.09.2734
Abstract209)      PDF (770KB)(437)       Save

In the research and application of multi-cross channel model, to maximize fault recovery of individual channel is the basis of the correctness to vote. There is some time redundancy in a task period. For a task processing in a given step, to summarize the time redundancy of pre-voting step, and assume fault-free on succedent step, then there will be a time redundancy on succedent step. The redundancy time of previous and succedent steps was counted, then a superior time window was used to do more deep recovery of fault. Based on the above ideas, a dynamic time series of multi-cross channel model was proposed, which was analyzed for deep recovery, and a backward recovery algorithm was given, which endowed more time to the fault unit, then the instantaneous fault could be eliminated to the utmost. Moreover, a monitoring logic was put forward to support the recovery algorithm. Theoretical analysis and experiments show that the backward recovery algorithm is effective to enhance the recovery rate and to reduce in the number of steps falling out. Compared with the statical recovery, the recovery rate increased by 47.49% and 72.35% respectively, and the number of out of step decreased by 58% and 85% respectively in the condition of 4 channel and 6 channel, which boosts the reliability of multi-cross channel model, especial in the condition of a large number of voting steps.

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