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Real-time pulmonary nodule detection algorithm combining attention and multipath fusion
Kui ZHAO, Huiqi QIU, Xu LI, Zhifei XU
Journal of Computer Applications    2024, 44 (3): 945-952.   DOI: 10.11772/j.issn.1001-9081.2023040424
Abstract152)   HTML3)    PDF (2387KB)(129)       Save

Existing single-stage target detection algorithms are insensitive to nodule detection in lung nodule detection, multiple up-samplings during feature extraction by Convolutional Neural Network (CNN) has difficult feature extraction and poor detection effect, and the existing pulmonary nodule detection algorithm models are complex and not conductive to practical application employment and implementation. To address the above problems, a real-time pulmonary nodule detection algorithm combining attention mechanism and multipath fusion was proposed, based on which the up-sampling algorithm was improved to effectively increase the detection accuracy of lung nodules and speed of model inference, the model size was small and easy to deploy. Firstly, the hybrid attention mechanism of channel and space was fused in the backbone network part of feature extraction. Secondly, the sampling algorithm was improved to enhance the quality of generated feature maps. Finally, the channels were established between different paths in the enhanced feature extraction network part to achieve the fusion of deep and shallow features, so the semantic and location information at different scales was fused. Experimental results on LUNA16 dataset show that, compared to the original YOLOv5s algorithm, the proposed algorithm achieves an improvement of 9.5, 6.9, and 8.7 percentage points in precision, recall, and average precision, respectively, with a frame rate of 131.6 frames/s, and a model weight file of only 14.2 MB, demonstrating that the proposed algorithm can detect lung nodules in real time with much higher accuracy than existing single-stage detection algorithms such as YOLOv3 and YOLOv8.

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Audio encryption algorithm in fractional domain based on cascaded chaotic system
XU Liyun, YAN Tao, QIAN Yuhua
Journal of Computer Applications    2021, 41 (9): 2623-2630.   DOI: 10.11772/j.issn.1001-9081.2020122044
Abstract327)      PDF (2308KB)(258)       Save
In order to ensure the security of audio signals in communication transmission, a fractional domain audio encryption algorithm based on cascaded chaotic system was proposed. Firstly, the audio signal was grouped. Secondly, the chaotic system was used to obtain the orders of fractional Fourier transform, and the order corresponding to each group data changed dynamically. Thirdly, the sampling fractional Fourier discrete transform with less computational complexity was used to obtain the fractional domain spectrum data of each group. Finally, the cascaded chaotic system was used to perform data encryption to the fractional domain of each group in turn, so as to realize the overall encryption of the audio signals. Experimental results show that the proposed algorithm is extremely sensitive to the key, and has the waveform and fractional domain spectrum of obtained encrypted signal more uniformly distributed and less correlated compared with those of the original signal. At the same time, compared with the frequency domain encryption and fixed-order fractional domain encryption methods, the proposed algorithm can effectively increase the key space while reducing the computational complexity. It can be seen that the proposed algorithm can satisfy the real-time and secure transmission requirements of audio signals effectively.
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Biomedical named entity recognition with graph network based on syntactic dependency parsing
XU Li, LI Jianhua
Journal of Computer Applications    2021, 41 (2): 357-362.   DOI: 10.11772/j.issn.1001-9081.2020050738
Abstract416)      PDF (845KB)(968)       Save
The existing biomedical named entity recognition methods do not use the syntactic information in the corpus, resulting in low precision. To solve this problem, a biomedical named entity recognition model with graph network based on syntactic dependency parsing was proposed. Firstly, the Convolutional Nerual Network (CNN) was used to generate character vectors which were concatenated with word vectors, then they were sent to Bidirectional Long Short-Term Memory (BiLSTM) network for training. Secondly, syntactic dependency parsing to the corpus was conducted with a sentence as a unit, and the adjacency matrix was constructed. Finally, the output of BiLSTM and the adjacency matrix constructed by syntactic dependency parsing were sent to Graph Convolutional Network (GCN) for training, and the graph attention mechanism was introduced to optimize the feature weights of adjacency nodes to obtain the model output. On JNLPBA dataset and NCBI-disease dataset, the proposed model reached F1 score of 76.91% and 87.80% respectively, which were 2.62 and 1.66 percentage points higher than those of the baseline model respectively. Experimental results prove that the proposed method can effectively improve the performance of the model in the biomedical named entity recognition task.
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3D model recognition based on capsule network
CAO Xiaowei, QU Zhijian, XU Lingling, LIU Xiaohong
Journal of Computer Applications    2020, 40 (5): 1309-1314.   DOI: 10.11772/j.issn.1001-9081.2019101750
Abstract514)      PDF (2645KB)(429)       Save

In order to solve the problem of feature information loss caused by the introduction of a large number of pooling layers in traditional convolutional neural networks, based on the feature of Capsule Network (CapsNet)——using vector neurons to save feature space information, a network model 3DSPNCapsNet (3D Small Pooling No dense Capsule Network) was proposed for recognizing 3D models. Using the new network structure, more representative features were extracted while the model complexity was reduced. And based on Dynamic Routing (DR) algorithm, Dynamic Routing-based algorithm with Length information (DRL) algorithm was proposed to optimize the iterative calculation process of capsule weights. Experimental results on ModelNet10 show that compared with 3DCapsNet (3D Capsule Network) and VoxNet, the proposed network achieves better recognition results, and has the average recognition accuracy on the original test set reached 95%. At the same time, the recognition ability of the network for the rotation 3D models was verified. After the rotation training set is appropriately extended, the average recognition rate of the proposed network for rotation models of different angles reaches 81%. The experimental results show that 3DSPNCapsNet has a good ability to recognize 3D models and their rotations.

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Learning monkey algorithm based on Lagrange interpolation to solve discounted {0-1} knapsack problem
XU Xiaoping, XU Li, WANG Feng, LIU Long
Journal of Computer Applications    2020, 40 (11): 3113-3118.   DOI: 10.11772/j.issn.1001-9081.2020040482
Abstract323)      PDF (613KB)(396)       Save
The purpose of the Discounted {0-1} Knapsack Problem (D{0-1}KP) is to maximize the sum of the value coefficients of all items loaded into the knapsack without exceeding the weight limit of the knapsack. In order to solve the problem of low accuracy when the existing algorithms solve the D{0-1}KP with large scale and high complexity, the Lagrange Interpolation based Learning Monkey Algorithm (LSTMA) was proposed. Firstly, the length of the visual field was redefined during the look process of the basic monkey algorithm. Then, the best individual in the population was introduced as the second pivot point and the search mechanism was adjusted during the jump process. Finally, the Lagrange interpolation operation was introduced after the jump process to improve the search performance of the algorithm. The simulation results on four types of examples show that LSMTA solves the D{0-1}KP with higher accuracy than the comparison algorithms, and it has good robustness.
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Euclidean embedding recommendation algorithm by fusing trust information
XU Lingling, QU Zhijian, XU Hongbo, CAO Xiaowei, LIU Xiaohong
Journal of Computer Applications    2019, 39 (10): 2829-2833.   DOI: 10.11772/j.issn.1001-9081.2019040597
Abstract315)      PDF (819KB)(245)       Save
To solve the sparse and cold start problems of recommendation system, a Trust Regularization Euclidean Embedding (TREE) algorithm by fusing trust information was proposed. Firstly, the Euclidean embedding model was employed to embed the user and project in the unified low-dimensional space. Secondly, to measure the trust information, both the project participation degree and user common scoring factor were brought into the user similarity calculation formula. Finally, a regularization term of social trust relationship was added to the Euclidean embedding model, and trust users with different preferences were used to constrain the location vectors of users and generate the recommendation results. In the experiments, the proposed TREE algorithm was compared with the Probabilistic Matrix Factorization (PMF), Social Regularization (SoReg), Social Matrix Factorization (SocialMF) and Recommend with Social Trust Ensemble (RSTE) algorithms. When dimensions are 5 and 10, TREE algorithm has the Root Mean Squared Error (RMSE) decreased by 1.60% and 5.03% respectively compared with the optimal algorithm RSTE on the dataset Filmtrust.While on the dataset Epinions, the RMSE of TREE algorithm was respectively 1.12% and 1.29% lower than that of the optimal algorithm SocialMF. Experimental results show that TREE algorithm further alleviate the sparse and cold start problems and improves the accuracy of scoring prediction.
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RSSI collaborative location algorithm of selecting preference accuracy for wireless sensor network
WANG Ming, XU Liang, HE Xiaomin
Journal of Computer Applications    2018, 38 (7): 1981-1988.   DOI: 10.11772/j.issn.1001-9081.2017123050
Abstract384)      PDF (1237KB)(313)       Save
Concerning insufficient and blind use of the Received Signal Strength Indicator (RSSI) information among unknown nodes, a new RSSI collaborative location algorithm of selecting preference accuracy for Wireless Sensor Network (WSN) was proposed. Firstly, the nodes with high locating accuracy were selected from coarsely located unknown nodes based on the RSSI thresholds. Secondly, subset judgment method was used to seek out the unknown nodes which were less affected by the environment as the second collaboration backbone nodes. Then, based on the positioning errors of the anchor nodes, anchor node replacement criterion was used to further extract the high-precision node from the secondary selected cooperative nodes as the optimal cooperative backbone nodes. Finally, the collaborative backbone nodes were used as the cooperative objects, and the unknown nodes were modified according to the precision priorities. In the simulation experiments, the average localization accuracy of the proposed algorithm was within 1.127 m in 100 m*100 m grids. In terms of locating accuracy, the average locating accuracy of the proposed algorithm is improved by 15% compared with the improved WSN locating algorithm using RSSI model. In terms of time efficiency, compared with the traditional RSSI collaborative location algorithm, the proposed algorithm improves the time efficiency by 20% under the same condition. It can be seen that the proposed algorithm can effectively enhance the locating accuracy, reduce computational complexity and improve time efficiency.
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Efficient block-based sampling algorithm for aggregation query processing on duplicate charged records
PAN Mingyu, ZHANG Lu, LONG Guobiao, LI Xianglong, MA Dongxue, XU Liang
Journal of Computer Applications    2018, 38 (6): 1596-1600.   DOI: 10.11772/j.issn.1001-9081.2017112632
Abstract380)      PDF (982KB)(312)       Save
The existing query analysis methods usually treat the entity resolution as an offline preprocessing process to clean the whole data set. However, with the continuous increasing of data size, such offline cleaning mode with high computing complexity has been difficult to meet the needs of real-time analysis in most applications. In order to solve the problem of aggregation query on duplicate charged records, a new method integrating entity resolution with approximate aggregation query processing was proposed. Firstly, a block-based sampling strategy was adopted to collect samples. Then, an entity recognition method was used to identify the duplicate entities on the sampled samples. Finally, the unbiased estimation of aggregated results was reconstructed according to the results of entity recognition. The proposed method avoids the time cost of identifying all entities, and returns the query results that satisfy user needs by identifying only a small number of sample data. The experimental results on both real dataset and synthetic dataset demonstrate the efficiency and reliability of the proposed method.
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Non-contact heart rate measurement method based on Eulerian video magnification
SU Peiquan, XU Liang, LIANG Yongjian
Journal of Computer Applications    2018, 38 (3): 916-922.   DOI: 10.11772/j.issn.1001-9081.2017071808
Abstract753)      PDF (1089KB)(562)       Save
Aiming at problems of inconvenient operations, large noise interference of same frequency band in heart rate, and great influence by environmental temperature in existing non-contact measurement of heart rate, a non-contact measurement method of heart rate based on Eulerian video magnification technology was proposed. Firstly, a tiny beating of radial artery of wrist was magnified by Eulerian video magnification technology. Secondly, a statistics of luminance variance for pixels in an enlarged video frame was performed in time domain. Meanwhile, skin area in YCrCb color space was segmented. Thirdly, the pulsing region of radial artery in a video was extracted by luminance variance statistics and skin segmentation incorporating with image morphological processing. Finally, the non-contact measurement of heart rate was implemented by time-frequency analysis through Fourier transform of luminance signal of radial artery extracted in time domain. The experimental results show that Root Mean Square Error (RMSE) is reduced by 50.5% and 32.6%, respectively compared to Independent Component Analysis (ICA) and pulse alternating current signal analysis; Mean Absolute Difference (MAD) is 12% lower than wavelet filtering method. In this paper, the proposed approach for non-contact measurement of heart rate has a good consistency with pulse oximeter measurement, which is satisfied to pharmaceutical industry standards. It also can be used in daily family health care and telemedicine to monitor heart rate.
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Broadcasting energy-efficiency optimization algorithms for asymmetric duty-cycled sensor network
XU Lijie
Journal of Computer Applications    2018, 38 (11): 3275-3281.   DOI: 10.11772/j.issn.1001-9081.2018040793
Abstract661)      PDF (1193KB)(395)       Save
Focused on the energy-efficiency optimization problem of broadcasting with minimum end-to-end delay constraint for asymmetric duty-cycled sensor network, a spatial-temporal state graph that represented the broadcasting spatial-temporal characteristics was first constructed, the target issue was modeled as the forwarding decision subset coverage problem, and then a Minimum-Cost forwarding decision Subset Coverage Algorithm (MC-SCA) and a Cost-Balanced forwarding decision Subset Coverage Algorithm (CB-SCA) were proposed. MC-SCA and CB-SCA both determined the optimal forwarding decision subset in an iterative way. MC-SCA greedily selected the forwarding decision with the least ratio of forwarding cost to the number of new covered nodes in each round of iteration, and CB-SCA greedily selected the forwarding decision which would bring less forward load and more new covered nodes in each round of iteration. In the comparison experiments with the typical Random Parent Node Selection Algorithm (RPNS-A), the total broadcasting energy consumption of MC-SCA decreases by 24.23% in average, and compared with RPNS-A, MC-SCA and the minimum-load-first greedy algorithm, the node maximum broadcasting load of CB-SCA respectively decreases by 48.69%, 65.21% and 10.64% in average, which implies that CB-SCA always achieves the better energy fairness of broadcasting.
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Multi-dimensional text clustering with user behavior characteristics
LI Wanying, HUANG Ruizhang, DING Zhiyuan, CHEN Yanping, XU Liyang
Journal of Computer Applications    2018, 38 (11): 3127-3131.   DOI: 10.11772/j.issn.1001-9081.2018041357
Abstract914)      PDF (970KB)(490)       Save
Traditional multi-dimensional text clustering generally extracts features from text contents, but seldom considers the interaction information between users and text data, such as likes, forwards, reviews, concerns, references, etc. Moreover, the traditional multi-dimension text clustering mainly integrates linearly multiple spatial dimensions and fails to consider the relationship between attributes in each dimension. In order to effectively use text-related user behavior information, a Multi-dimensional Text Clustering with User Behavior Characteristics (MTCUBC) was proposed. According to the principle that the similarity between texts should be consistent in different spaces, the similarity was adjusted by using the user behavior information as the constraints of the text content clustering, and then the distance between the texts was improved by the metric learning method, so that the clustering effect was improved. Extensive experiments conduct and verify that the proposed MTCUBC model is effective, and the results present obvious advantages in high-dimensional sparse data compared to linearly combined multi-dimensional clustering.
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Multi-source text topic mining model based on Dirichlet multinomial allocation model
XU Liyang, HUANG Ruizhang, CHEN Yanping, QIAN Zhisen, LI Wanying
Journal of Computer Applications    2018, 38 (11): 3094-3099.   DOI: 10.11772/j.issn.1001-9081.2018041359
Abstract424)      PDF (1100KB)(463)       Save
With the rapid increase of text data sources, topic mining for multi-source text data becomes the research focus of text mining. Since the traditional topic model is mainly oriented to single-source, there are many limitations to directly apply to multi-source. Therefore, a topic model for multi-source based on Dirichlet Multinomial Allocation model (DMA) was proposed considering the difference between sources of topic word-distribution and the nonparametric clustering quality of DMA, namely MSDMA (Multi-Source Dirichlet Multinomial Allocation). The main contributions of the proposed model are as follows:1) it takes into account the characteristics of each source itself when modeling the topic, and can learn the source-specific word distributions of topic k; 2) it can improve the topic discovery performance of high noise and low information through knowledge sharing; 3) it can automatically learn the number of topics within each source without the need for human pre-given. The experimental results in the simulated data set and two real datasets indicate that the proposed model can extract topic information more effectively and efficiently than the state-of-the-art topic models.
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Air target threat assessment based on improved ACPSO algorithm and LSSVM
XU Lingkai, YANG Rennong, ZUO Jialiang
Journal of Computer Applications    2017, 37 (9): 2712-2716.   DOI: 10.11772/j.issn.1001-9081.2017.09.2712
Abstract538)      PDF (903KB)(431)       Save
The key link of air defense command and control system is to evaluate the threat degree of air target according to target situation information, the accuracy of the assessment will have a significant impact on air defense operations. Aiming at the shortcomings of traditional evaluation methods, such as poor real-time performance, heavy workload, low evaluation accuracy, and unable to evaluate multiple objectives simultaneously, a method of air target threat assessment based on Adaptive Crossbreeding Particle Swarm Optimization (ACPSO) and Least Squares Support Vector Machine (LSSVM) was proposed. Firstly, according to the air target situation information, the framework of threat assessment system was constructed. Then, ACPSO algorithm was used to optimize the regularization parameter and kernel function parameter in LSSVM. In order to overcome the disadvantages of the traditional crossbreeding mechanism, an improved cross-hybridization mechanism was proposed, and the crossbreeding probability was adjusted adaptively. Finally, the training and evaluation results of the systems were compared and analyzed, and the multi-target real-time dynamic threat assessment was realized by the optimized system. Simulation results show that the proposed method has the advantages of high accuracy and short time required, and can be used to evaluate multiple targets simultaneously. It provides an effective solution to evaluate the threat of air targets.
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Interval-value attribute reduction algorithm for meteorological observation data based on genetic algorithm
ZHENG Zhongren, CHENG Yong, WANG Jun, ZHONG Shuiming, XU Liya
Journal of Computer Applications    2017, 37 (9): 2678-2683.   DOI: 10.11772/j.issn.1001-9081.2017.09.2678
Abstract510)      PDF (1007KB)(475)       Save
Aiming at the problems that the purpose of the meteorological observation data acquisition is weak, the redundancy of data is high, and the number of single values in the observation data interval is large, the precision of equivalence partitioning is low, an attribute reduction algorithm for Meteorological Observation data Interval-value based on Genetic Algorithm (MOIvGA) was proposed. Firstly, by improving the similarity degree of interval value, the proposed algorithm could be suitable for both single value equivalence relation judgment and interval value similarity analysis. Secondly, the convergence of the algorithm was improved by the improved adaptive genetic algorithm. Finally, the simulation experiments show that the number of the iterations of the proposed algorithm is reduced by 22, compared with the method which operated AGAv (Adaptive Genetic Attribute reduction) algorithm to solve the optimal value. In the time interval of 1 hour precipitation classification, the average classification accuracy of the MOIvGA (λ-Reduction in Interval-valued decision table based on Dependence) algorithm is 6.3% higher than that of RIvD algorithm; the accuracy of no rain forecasting is increased by 7.13%; at the same time, the classification accuracy can be significantly impoved by the attribute subset received by operating the MOIvGA algorithm. Therefore, the MOIvGA algorithm can increase the convergence rate and the classification accuracy in the analysis of interval value meteorological observation data.
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Path planning for restaurant service robot based on improved genetic algorithm
XU Lin, FAN Xinwei
Journal of Computer Applications    2017, 37 (7): 1967-1971.   DOI: 10.11772/j.issn.1001-9081.2017.07.1967
Abstract628)      PDF (808KB)(474)       Save
Since the Genetic Algorithm (GA) is easy to produce premature phenomenon and has slow convergence rate, an improved GA based on Traditional GA (TGA), called HLGA (Halton-Levenshtein Genetic Algorithm), was proposed for path planning of real restaurant service robots. Firstly, the similarity method based on edit distance optimized the initial population of quasi-random sequence; secondly, the improved crossover probability and mutation probability adjustment formula based on the adaptive algorithm were adopted to cross and mutate the individuals after they had been selected. Finally, the individual fitness values of the safety evaluation factor functions were calculated, and the global optimal solution was obtained by comparison and iteration. Through theoretical analysis and Matlab simulation, the running time of HLGA was decreased by 6.92 seconds and 1.79 seconds compared with TGA and Adaptive Genetic Algorithm based on Improved independent Similarity (ISAGA), and the actual path of planning was more secure and smooth. The simulation results show that HLGA can effectively improve the quality of path planning in practical applications, meanwhile reduces the searching space and the planning time.
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Dynamic clustering target tracking based on energy optimization in wireless sensor networks
WEI Mingdong, HE Xiaomin, XU Liang
Journal of Computer Applications    2017, 37 (6): 1539-1544.   DOI: 10.11772/j.issn.1001-9081.2017.06.1539
Abstract506)      PDF (945KB)(482)       Save
Concerning the problem of high energy consumption caused by data collision and cluster selection process in dynamic clustering target tracking of Wireless Sensor Network (WSN), a dynamic clustering method based on energy optimization for WSN was proposed. Firstly, a time division election transmission model was proposed, which avoided data collision actively to reduce energy consumption of nodes in a dynamic cluster. Secondly, based on energy information and tracking quality, the energy-balanced farthest node scheduling strategy was proposed, which optimized custer head node scheduling. Finally, according to the weighted centroid localization algorithm, the target tracking task was completed. Under the environment of random deployment of nodes, the experimental results show that, the average tracking accuracy of the proposed method for non-linear moving objects was 0.65 m, which is equivalent to that of Dynamic Cluster Member Selection method for multi-target tracking (DCMS), and improved by 45.8% compared to Distributed Event Localization and Tracking Algorithm (DELTA). Compared with DCMS and DELTA, the proposed algorithm can effectively reduce energy consumption of the dynamic tracking clusters by 61.1% and prolong the network lifetime.
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Summary of facial expression recognition methods based on image
XU Linlin, ZHANG Shumei, ZHAO Junli
Journal of Computer Applications    2017, 37 (12): 3509-3516.   DOI: 10.11772/j.issn.1001-9081.2017.12.3509
Abstract876)      PDF (1504KB)(1421)       Save
In recent years, facial expression recognition has received extensive attention in education, medicine, psychoanalysis and business. Aiming at the problems of not systematic enough and fuzzy concept of facial expression recognition method, the steps and methods of facial expression recognition were reviewed and discussed. Firstly, the commonly used facial expression databases were introduced and the development of facial expression recognition was reviewed. Then, two aspects of facial expression recognition were introduced, such as facial expression coding and facial expression recognition. The four processes of face facial expression recognition were summarized. The classical algorithms, the basic principles of these algorithms and the comparisons of their advantages and disadvantages were summarized emphatically in the two processes of feature extraction and facial expression classification. Finally, the existing problems and possible development trends in the future of the current facial expression recognition were pointed out.
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Missile hit prediction model based on adaptively-mutated chaotic particle swarm optimization and support vector machine
XU Lingkai, YANG Rennong, ZHANG Binchao, ZUO Jialiang
Journal of Computer Applications    2017, 37 (10): 3024-3028.   DOI: 10.11772/j.issn.1001-9081.2017.10.3024
Abstract662)      PDF (812KB)(441)       Save
Intelligent air combat is a hot research topic in military aviation field and missile hit prediction is an important part of intelligent air combat. Aiming at the shortcomings of insufficient research on missile hit prediction, poor optimization ability of the algorithm, and low prediction accuracy of the model, a missile hit prediction model based on Adaptively-Mutated Chaotic Particle Swarm Optimization (AMCPSO) and Support Vector Machine (SVM) was proposed. Firstly, feature extraction of air combat data was carried out to build sample library for model training; then, the improved AMCPSO algorithm was used to optimize the penalty factor C and the kernel function parameter g in SVM, and the optimized model was used to predict the samples; finally, comparison tests with classical PSO algorithm, the BP neural network method and the method based on lattice were made. The results show that the global and local optimization ability of the proposed algorithm are both stronger, and the prediction accuracy of the proposed model is higher, which can provide a reference for missile hit prediction research.
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Beamforming based localization algorithm in 60GHz wireless local area networks
LIU Xing, ZHANG Hao, XU Lingwei
Journal of Computer Applications    2016, 36 (8): 2170-2174.   DOI: 10.11772/j.issn.1001-9081.2016.08.2170
Abstract397)      PDF (731KB)(345)       Save
Concerning ranging difficulties with 60GHz signals in Non Line of Sight (NLOS) conditions, a new positioning algorithm based on beamforming in Wireless Local Area Network (WLAN) was proposed. Firstly, the beamforming technology was applied to search the strongest path by adjusting receiving antennas along the channel path with the maximum power.The searching robustness was enhanced and the location coverage was expanded. Secondly, the time delay bias in NLOS conditions was modeled as a Gaussian random variable to reconstruct the NLOS measurements. Finally, to further improve the positioning accuracy, the outlier detection mechanism was introduced by setting a reasonable detection threshold. The localization simulation experiments were conducted on Matlab using STAs-STAs (STAtions-STAtions) channel model, the Time of Arrival (TOA) localization algorithm based on traditional coherent estimation method achieved the average positioning error at about 2m, and the probability of 1m localization accuracy was just 0.5% under NLOS conditions, while the proposed algorithm achieved the average positioning error at 1.02cm, and the probability of 1m localization accuracy reached 94%. Simulation results show that the beamforming technology is an effective solution to 60GHz localization in NLOS conditions, and the localization accuracy and the probability of successful localization are effectively improved.
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Research and application of high-precision indoor location-aware big data
DENG Zhongliang, ZHANG Senjie, JIAO Jichao, XU Lianming
Journal of Computer Applications    2016, 36 (2): 295-300.   DOI: 10.11772/j.issn.1001-9081.2016.02.0295
Abstract621)      PDF (985KB)(1406)       Save
With the development of indoor positioning technology, a large amount of indoor location data and user data for consumer behavior makes the indoor Location Big Data (LBD) research and application possible. High-precision indoor location technology breaks the bottleneck of indoor location data with low accuracy. By clustering the indoor location data and dimension reduction pretreatment, a mining model was set up to extract the characteristics of custom and flow in the indoor shopping area. Then using the associated user consumption behavior to predict the characteristics of consumer behaviors, a collaborative mining method and architecture for large data of indoor location was put forward. Experiments on location dataset of billions of users in an airport and a shopping mall in Xidan were conducted. The results verify the accuracy and feasibility of the mining method based on this architecture of indoor positioning data.
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Distributed fault detection for wireless sensor network based on cumulative sum control chart
LIU Qiuyue, CHENG Yong, WANG Jun, ZHONG Shuiming, XU Liya
Journal of Computer Applications    2016, 36 (11): 3016-3020.   DOI: 10.11772/j.issn.1001-9081.2016.11.3016
Abstract652)      PDF (908KB)(439)       Save
With the stringent resources and distributed nature in wireless sensor networks, fault diagnosis of sensor nodes faces great challenges. In order to solve the problem that the existing approaches of diagnosing sensor networks have high false alarm ratio and considerable computation redundancy on nodes, a new fault detection mechanism based on Cumulative Sum Chart (CUSUM) and neighbor-coordination was proposed. Firstly, the historical data on a single node were analyzed by CUSUM to improve the sensitivity of fault diagnosis and locate the change point. Then, the fault nodes were detected though judging the status of nodes by the data exchange between neighbor nodes. The experimental results show that the detection accuracy is over 97.7% and the false alarm ratio is below 2% when the sensor fault probability in wireless sensor networks is up to 35%. Hence, the proposed algorithm has a high detection accuracy and low false alarm ratio even in the conditions of high fault probabilities and reduces the influence of sensor fault probability clearly.
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Design of data traffic optimization system for large-scale wireless sensor networks
CHEN Yi, XU Li, ZHANG Meiping
Journal of Computer Applications    2015, 35 (4): 905-909.   DOI: 10.11772/j.issn.1001-9081.2015.04.0905
Abstract1069)      PDF (957KB)(1048)       Save

Aiming at the problem that the data traffic rises with the increase of data visitors in large-scale Wireless Sensor Networks (WSN), a data traffic optimization WSN system framework was designed and implemented to build large-scale WSN and reduce the network data traffic. The IPv6 and IPv6 over Low Power Wireless Personal Area Network (6LoWPAN) technology were adopted to build large-scale WSN. To integrate the WSN and traditional Internet, the Message Queuing Telemetry Transport (MQTT) and Message Queuing Telemetry Transport for Sensor Network (MQTT-SN) protocols were deployed in application layer to build system publish/subscribe model. The experimental results show that, when system has 5 sensor nodes, compared with the Constrained Application Protocol (CoAP) based WSN system, the data traffic of the proposed system is 18% of the former. It proves that the proposed system framework can effectively control the impact caused by increasing visitors to WSN data traffic.

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Fast intra prediction algorithm for high efficiency video coding
XU Dongxu LIN Qiwei
Journal of Computer Applications    2014, 34 (8): 2375-2379.   DOI: 10.11772/j.issn.1001-9081.2014.08.2375
Abstract217)      PDF (740KB)(533)       Save

To further reduce the great computational complexity for High Efficiency Video Coding (HEVC) intra prediction, a novel algorithm was proposed in this paper. First, in Coding Unit (CU) level, the minimum Sum of Absolute Transformed Difference (SATD) of current CU was used to decide an early termination for the split of this CU at each depth level: if the minimum SATD of this CU is smaller than the given threshold value. Meanwhile, based on statistical analysis, the probabilities of each candidate prediction modes being optimal mode were used to further reduce the number of candidate modes which have almost no chance to be selected as the best mode. The experimental results show that, the proposed algorithm can save an average of 30.5% of the encoding time with negligible loss of coding efficiency (only 0.02dB Y-PSNR(Y-Peak Signal-to-Noise Ratio) loss) compared with the reference model HM10.1. Besides, the proposed algorithm is easy to provide software and hardware implementations, and it is also easy to be combined with other methods to further reduce the great computational complexity for HEVC intra coding.

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Single-sink scheduling problem in wireless sensor networks
ZHANG Meiping GU Yu XU Li
Journal of Computer Applications    2014, 34 (7): 1941-1946.   DOI: 10.11772/j.issn.1001-9081.2014.07.1941
Abstract237)      PDF (1055KB)(350)       Save

This article focused on the mobile sink scheduling problem in Wireless Sensor Networks (WSN). A mobile single-sink scheduling algorithm in wireless sensor networks was proposed based on Linear Programming (LP). Firstly, the problem was mathematically modeled and formulated in time domain, and the problem was re-formulated from time to space domain to reduce the complexity. Then a polynomial-time optimal algorithm was proposed based on linear programming. The simulations confirm the efficiency of the algorithm and the results show that the algorithm can significantly improve the network lifetime of wireless sensor networks.

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Remote sensing image classification using layer-by-layer feature associative conditional random field
YANG Yun XU Li
Journal of Computer Applications    2014, 34 (6): 1741-1745.   DOI: 10.11772/j.issn.1001-9081.2014.06.1741
Abstract232)      PDF (868KB)(418)       Save

For the difficulty of expressing spatial context in classification of high resolution remote sensing imagery, a new multi-scale Conditional Random Field (CRF)model was proposed here. Specifically, a given image was represented as three superpixel layers respectively being region, object and scene from fine to coarse firstly. Then features were extracted layer-by-layer, and those features from the three layers were associated with each other to form a feature vector for each node in region layer. Secondly, Support Vector Machine (SVM) was adopted to define association potential function, and Potts model weighted by feature contrast function was used to define interaction potential function of CRF model, thus a layer-by-layer feature associative and multi-scale SVM-CRF model was formed. To confirm the effectiveness of the proposed model in classification, experiments on two complex scenes from Quickbird remote sensing imagery were developed. The results show that the proposed model achieves an improved accuracy averagely 2.68%, 2.37%, 3.75% higher than that of SVM-CRF model based on either region, object or scene layer, also it consumes less time in classification.

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Modeling of marine ecology ontology
YUN Hongyan XU Liangjian GUO Zhenbo WEI Xiaoyan
Journal of Computer Applications    2014, 34 (4): 1105-1108.   DOI: 10.11772/j.issn.1001-9081.2014.04.1105
Abstract461)      PDF (609KB)(391)       Save

According to characters of marine ecology domain knowledge, a marine ecology knowledge organization model was proposed. Referring to engineering field literature and the device-function knowledge representation theory that the "function" concept was used to describe marine ecology functional process; a viewpoint of device-function was fixed, a domain upper ontology for marine ecosystem was presented, and then marine ecological conceptual model and marine ecology OWL ontology were constructed. By extending OWL-DL, OWL-Process model oriented function-process was proposed, and then marine ecology function-process ontology instance was constructed. Based on constructed marine ecology ontology repository, marine ecological knowledge management system was developed. The ontology application system provides marine ecology knowledge query and crisis early warning functions; and it also verifies the validity, rationality and feasibility of constructed marine ecology ontology.

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Analysis and suppression of influence on spotbeam selection of GMR-1 system under antenna oscillation
LIN Xiaoxu LIU Naijin QIAN Jinxi ZHAO Danfeng
Journal of Computer Applications    2014, 34 (2): 346-350.  
Abstract442)      PDF (758KB)(1227)       Save
Considering the antenna oscillation phenomenon, the performance of spotbeam selection in Geostationary Earth Orbit Mobile Radio Interface (GMR-1) system under antenna oscillation was analyzed and an improved spotbeam selection algorithm was proposed. The improved algorithm could dynamically set hysteresis using the distance between the Mobile Earth Station (MES) and its Gateway Station (GS). A simulation model was implemented using OPNET. The simulation results show that the MES at different location is influenced by antenna oscillation to different extent. Besides, the wrong times of spotbeam selection increases with the increase of hysteresis and the maximum amplitude in the traditional algorithm. Finally, the improved algorithm can reduce the wrong times of spotbeam selection and restrain the influence on spotbeam selection under antenna oscillation efficiently.
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Identification method of system reliability structure
LI Qingmin LI Hua XU Li YUAN Wei
Journal of Computer Applications    2014, 34 (11): 3340-3343.   DOI: 10.11772/j.issn.1001-9081.2014.11.3340
Abstract181)      PDF (591KB)(456)       Save

In integrated support engineering, the number of components in reliability block diagram is large, the level of mastering the principle of system is required to be high and the operational data is always incomplete. To resolve these problems, a method that identifies the reliability structure of system using the information of operational data and the reliability of the units was proposed. The system reliability was estimated by using the system performance information. In addition, all reliability structure models was traversed and the theoretical reliability was calculated with the system's units reliability information, then the deviations between the estimated value of system reliability and all the reliability theoretical values were calculated, and the identification results by the first N reliability structure models of the lowest deviation was outputted after sorting the deviations. The calculation results of a given example show that the combined system based on the voting reliability structure can be identified with the probability of around 80%, decreases to 3% of the scope out of all possible forms, it can significantly reduce the workload of the researcher to identify the system reliability structure.

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Image denoising algorithm using fractional-order integral with edge compensation
HUANG Guo CHEN Qingli XU Li MEN Tao PU Yifei
Journal of Computer Applications    2014, 34 (10): 2957-2962.   DOI: 10.11772/j.issn.1001-9081.2014.10.2957
Abstract211)      PDF (1008KB)(378)       Save

To solve the problem of losing edge and texture information in the existing image denoising algorithms based on fractional-order integral, an image denoising algorithm using fractional-order integral with edge compensation was presented. The fractional-order integral operator has the performance of sharp low-pass. The Cauchy integral formula was introduced into digital image denoising, and the image numerical calculation of fractional-order integral was achieved by the method of slope approximation. In the process of iterative denoising, the algorithm built denoising mask by setting higher tiny fractional-order integral order at the rising stage of image Signal-to-Noise Ratio (SNR); and the algorithm built denoising mask by setting lower small fractional-order integral order at the declining stage of image SNR. Additionally, it could partially restore the image edge and texture information by the mechanism of edge compensation. The image denoising algorithm using fractional-order integral proposed in this paper makes use of different strategies of the fractional-order integral order and edge compensation mechanism in the process of iterative denoising. The experimental results show that compared with traditional denoising algorithm, the denoising algorithm proposed in this paper can remove the noise to obtain higher SNR and better visual effect while appropriately restoring the edge and texture information of image.

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Secure and distributed cloud storage model from threshold attribute-based encryption
WU Shengyan XU Li LIN Changlu
Journal of Computer Applications    2013, 33 (07): 1880-1884.   DOI: 10.11772/j.issn.1001-9081.2013.07.1880
Abstract855)      PDF (941KB)(710)       Save
Since there are more and more security issues in cloud storage, this paper designed a new secure and distributed cloud storage model based on the threshold Attribute-Based Encryption (ABE). Three phases in the model included: the encryption phase, the data storage phase and the decryption phase, and all messages in these phases were distributed through the whole process. It not only enhanced the security of the storage data by using the ABE but also supported the threshold decryption and allowed to add or remove the arbitrary attribute authorities, with the use of the multi-attribute authorities method in the model. In the data storage phase, this paper used the distributed erasure code to improve the robustness of our model and this model could resist against collusion attack. It can be applied in some special cloud situations and provides secure cloud storage service for users.
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