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Image denoising network based on local and global feature decoupling
Yuwei DING, Hongbo SHI, Jie LI, Min LIANG
Journal of Computer Applications    2024, 44 (8): 2571-2579.   DOI: 10.11772/j.issn.1001-9081.2023081131
Abstract47)   HTML2)    PDF (2935KB)(27)       Save

Concerning the problem that current Transformer-based algorithms focus on capturing the global features of images, but ignore the key role of local features to restore image details, an image denoising network based on local and global feature decoupling was proposed. The proposed network included two multi-scale branches based on Hybrid Transformer Block (HTB) and a single-scale branch based on Convolutional Neural Network (CNN), aiming at combining powerful global modeling capability of HTB with local modeling advantage of HTB, and yielding outputs with enriched contextual information and precise spatial details. Within the HTB, self-attention mechanism was employed to adaptively model spatial- and channel-dimensional dependencies activating a wider range of input pixels for reconstruction. Given the potential information conflicts across different branches, feature transfer block was designed to facilitate cross-branch propagation of global features and suppress low-frequency information, thereby ensuring collaborative interactions among the branches. Experimental results showed that: on the real-world image dataset SIDD, compared with Transformer-based denoising network Uformer, the proposed network improved Peak Signal-to-Noise Ratio (PSNR) by 0.09 dB and Structural SIMilarity (SSIM) by 0.001; on the synthetic image dataset Urban100, compared with multi-stage denoising network MSPNet (Multi-Stage Progressive denoising Network), the average PSNR of the proposed network was improved by 0.41 dB. It can be seen that the proposed network effectively removes image noise and reconstructs finer texture details.

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Multimodal sentiment analysis network with self-supervision and multi-layer cross attention
Kaipeng XUE, Tao XU, Chunjie LIAO
Journal of Computer Applications    2024, 44 (8): 2387-2392.   DOI: 10.11772/j.issn.1001-9081.2023081209
Abstract33)   HTML7)    PDF (1572KB)(23)       Save

Aiming at the problems of incomplete intra-modal information, poor inter-modal interaction, and difficulty in training in multimodal sentiment analysis, a Multimodal Sentiment analysis network with Self-supervision and Multi-layer cross Attention fusion (MSSM) was proposed with Visual-and-Language Pre-training (VLP) model applied to the field of multimodal sentiment analysis. The visual encoder module was enhanced through self-supervised learning, and multi-layer cross attention was added to better model textual and visual features. Thus, the intra-modal information was made more abundant and complete, and the inter-modal information interaction was made more sufficient. Besides, the fast and memory-efficient exact attention with IO-awareness: FlashAttention was adopted in the proposed algorithm to address the high complexity of attention computation in Transformer. Experimental results show that compared with the current mainstream model Contrastive Language-Image Pre-training (CLIP), MSSM improves the accuracy by 3.6 percentage points on the processed MVSA-S dataset and 2.2 percentage points on MVSA-M dataset, proving that the proposed network can effectively improve the integrity of multimodal information fusion while reducing computational cost.

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Classroom speech emotion recognition method based on multi-scale temporal-aware network
Juxiang ZHOU, Jinsheng LIU, Jianhou GAN, Di WU, Zijie LI
Journal of Computer Applications    2024, 44 (5): 1636-1643.   DOI: 10.11772/j.issn.1001-9081.2023050663
Abstract275)   HTML10)    PDF (4548KB)(628)       Save

Speech emotion recognition has been widely used in multi-scenario intelligent systems in recent years, and it also provides the possibility to realize intelligent analysis of teaching behaviors in smart classroom environments. Classroom speech emotion recognition technology can be used to automatically recognize the emotional states of teachers and students during classroom teaching, help teachers understand their own teaching styles and grasp students’ classroom learning status in a timely manner, thereby achieving the purpose of precise teaching. For the classroom speech emotion recognition task, firstly, classroom teaching videos were collected from primary and secondary schools, the audio was extracted, and manually segmented and annotated to construct a primary and secondary school teaching speech emotion corpus containing six emotion categories. Secondly, based on the Temporal Convolutional Network (TCN) and cross-gated mechanism, dual temporal convolution channels were designed to extract multi-scale cross-fusion features. Finally, a dynamic weight fusion strategy was adopted to adjust the contributions of features at different scales, reduce the interference of non-important features on the recognition results, and further enhance the representation and learning ability of the model. Experimental results show that the proposed method is superior to advanced models such as TIM-Net (Temporal-aware bI-direction Multi-scale Network), GM-TCNet (Gated Multi-scale Temporal Convolutional Network), and CTL-MTNet (CapsNet and Transfer Learning-based Mixed Task Net) on multiple public datasets, and its UAR (Unweighted Average Recall) and WAR (Weighted Average Recall) reach 90.58% and 90.45% respectively in real classroom speech emotion recognition task.

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Survey on tile-based viewport adaptive streaming scheme of panoramic video
Junjie LI, Yumei WANG, Zhijun LI, Yu LIU
Journal of Computer Applications    2024, 44 (2): 536-547.   DOI: 10.11772/j.issn.1001-9081.2023020209
Abstract219)   HTML11)    PDF (2319KB)(413)       Save

Panoramic videos have attracted wide attention due to their unique immersive and interactive experience. The high bandwidth and low delay required for wireless streaming of panoramic videos have brought challenges to existing network streaming systems. Tile-based viewport adaptive streaming can effectively alleviate the streaming pressure brought by panoramic video, and has become the current mainstream scheme and hot research topic. By analyzing the research status and development trend of tile-based viewport adaptive streaming, the two important modules of this streaming scheme, namely viewport prediction and bit rate allocation, were discussed, and the methods in relevant fields were summarized from different perspectives. Firstly, based on the panoramic video streaming framework, the relevant technologies were clarified. Secondly, the user experience quality indicators to evaluate the performance of the streaming system were introduced from the subjective and objective dimensions. Then, the classic research methods were summarized from the aspects of viewport prediction and bit rate allocation. Finally, the future development trend of panoramic video streaming was discussed based on the current research status.

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Small target detection model in overlooking scenes on tower cranes based on improved real-time detection Transformer
Yudong PANG, Zhixing LI, Weijie LIU, Tianhao LI, Ningning WANG
Journal of Computer Applications    2024, 44 (12): 3922-3929.   DOI: 10.11772/j.issn.1001-9081.2023121796
Abstract327)   HTML8)    PDF (3128KB)(256)       Save

In view of a series of problems of security guarantee of construction site personnel such as casualties led by falling objects and tower crane collapse caused by mutual collision of tower hooks, a small target detection model in overlooking scenes on tower cranes based on improved Real-Time DEtection TRansformer (RT-DETR) was proposed. Firstly, the multiple training and single inference structures designed by applying the idea of model reparameterization were added to the original model to improve the detection speed. Secondly, the convolution module in FasterNet Block was redesigned to replace BasicBlock in the original BackBone to improve performance of the detection model. Thirdly, the new loss function Inner-SIoU (Inner-Structured Intersection over Union) was utilized to further improve precision and convergence speed of the model. Finally, the ablation and comparison experiments were conducted to verify the model performance. The results show that, in detection of the small target images in overlooking scenes on tower cranes, the proposed model achieves the precision of 94.7%, which is higher than that of the original RT-DETR model by 6.1 percentage points. At the same time, the Frames Per Second (FPS) of the proposed model reaches 59.7, and the detection speed is improved by 21% compared with the original model. The Average Precision (AP) of the proposed model on the public dataset COCO 2017 is 2.4, 1.5, and 1.3 percentage points higher than those of YOLOv5, YOLOv7, and YOLOv8, respectively. It can be seen that the proposed model meets the precision and speed requirements for small target detection in overlooking scenes on tower cranes.

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Parallel medical image registration model based on convolutional neural network and Transformer
Xin ZHAO, Xinjie LI, Jian XU, Buyun LIU, Xiang BI
Journal of Computer Applications    2024, 44 (12): 3915-3921.   DOI: 10.11772/j.issn.1001-9081.2023121828
Abstract232)   HTML5)    PDF (2554KB)(129)       Save

Medical image registration models aim to establish the correspondence of anatomical positions between images. The traditional image registration method obtains the deformation field through continuous iteration, which is time-consuming and has low accuracy. The deep neural networks not only achieve end-to-end generation of deformation fields, thereby speeding up the generation of deformation fields, but also further improve the accuracy of image registration. However, all of the current deep learning registration models use single Convolutional Neural Network (CNN) or Transformer architecture, and have the problems such as the inability to fully utilize the advantages of the combination of CNN and Transformer, resulting in insufficient registration accuracy, and the inability to maintain the original topology effectively after image registration. To solve these problems, a parallel medical image registration model based on CNN and Transformer — PPCTNet (Parallel Processing of CNN and Transformer Network) was proposed. Firstly, the model was constructed using Swin Transformer, which currently has the excellent registration accuracy, and LOCV-Net (Lightweight attentiOn-based ConVolutional Network), a very lightweight CNN. Then, the feature information extracted by Swin Transformer and LOCV-Net were fully integrated by designing a fusion strategy, so that the model not only had the local feature extraction capability of CNN and the long-distance dependency capability of Transformer, but also had the advantage of being lightweight. Finally, based on the brain Magnetic Resonance Imaging (MRI) dataset, PPCTNet was compared with 10 classical image alignment models. The results show that compared to the currently excellent registration model TransMorph (hybrid Transformer-ConvNet network for image registration), PPCTNet has the highest registration accuracy 0.5 percentage points higher, and the folding rate of deformation field 1.56 percentage points reduced, maintaining the topological structures of the registered images. Besides, compared with TransMorph, PPCTNet has the parameters reduced by 10.39×106, and the computational cost reduced by 278×109, which reflects the lightweight advantage of PPCTNet.

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Disease sample classification algorithm by Bayesian network with gene association analysis
Zhijie LI, Xuhong LIAO, Yuanxiang LI, Qinglan LI
Journal of Computer Applications    2024, 44 (11): 3449-3458.   DOI: 10.11772/j.issn.1001-9081.2024030398
Abstract71)   HTML2)    PDF (644KB)(130)       Save

As a specific type of big data in biology, similarity of gene expression data is not based on Euclidean distance but on whether gene expression values show a trend of both rise and fall together, although they are all ordinary real values. The current gene Bayesian network uses gene expression level values as node random variables and does not reflect the similarity of this kind of subspace pattern. Therefore, a Bayesian network disease Classification algorithm based on Gene Association analysis (BCGA) was proposed to learn Bayesian networks from labeled disease sample-gene expression data and predict the classification of new disease samples. Firstly, disease samples were discretized and filtered to select genes, and the dimensionally reduced gene expression values were sorted and replaced with gene column subscripts. Secondly, the subscript sequence of gene column was decomposed into a set of atomic sequences with a length of 2, and the frequent atomic sequence of this set was corresponding to the association of a pair of genes. Finally, causal relationships were measured through gene association entropy for Bayesian network structure learning. Besides, the parameter learning of BCGA became easy, and the conditional probability distribution of a gene node was able to be obtained by counting the atomic sequence occurrence frequency of the gene and its parent node gene. Experimental results on multiple tumor and non-tumor gene expression datasets show that BCGA significantly improves disease classification accuracy and effectively reduces analysis time compared to the existing similar algorithms. In addition, BCGA uses gene association entropy instead of conditional independence, and gene atomic sequences instead of gene expression values, which can better fit gene expression data better.

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Deep bi-modal source domain symmetrical transfer learning for cross-modal retrieval
Qiujie LIU, Yuan WAN, Jie WU
Journal of Computer Applications    2024, 44 (1): 24-31.   DOI: 10.11772/j.issn.1001-9081.2023010047
Abstract358)   HTML10)    PDF (2170KB)(191)       Save

Cross-modal retrieval based on deep network often faces the challenge of insufficient cross-training data, which limits the training effect and easily leads to over-fitting. Transfer learning is an effective way to solve the problem of insufficient training data by learning the training data in the source domain and transferring the acquired knowledge to the target domain. However, most of the existing transfer learning methods focus on transferring knowledge from single-modal (like image) source domain to cross-modal (like image and text) target domain. If there is multiple modal information in the source domain, this asymmetric transfer would ignore the potential inter-modal semantic information contained in the source domain. At the same time, the similarity of the same modals in the source domain and the target domain cannot be well extracted, thereby reducing the domain difference. Therefore, a Deep Bi-modal source domain Symmetrical Transfer Learning for cross-modal retrieval (DBSTL) method was proposed. The purpose of this method is to realize the knowledge transfer from bi-modal source domain to multi-modal target domain, and obtain the common representation of cross-modal data. DBSTL consists of modal symmetric transfer subnet and semantic consistency learning subnet. With hybrid symmetric structure adopted in symmetric modal transfer subnet, the information between modals was more consistent to each other and the difference between source domain and target domain was reduced by this subnet. In semantic consistency learning subnet, all modalities shared the same common presentation layer, and the cross-modal semantic consistency was ensured under the guidance of the supervision information of the target domain. Experimental results show that on Pascal, NUS-WIDE-10k and Wikipedia datasets, the mean Average Precision (mAP) of the proposed method is improved by about 8.4, 0.4 and 1.2 percentage points compared with the best result obtained by the comparison methods respectively. DBSTL makes full use of the potential information of the dual-modal source domain to conduct symmetric transfer learning, ensures the semantic consistency between modals under the guidance of the supervision information, and improves the similarity of image and text distribution in the public representation space.

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Image super-resolution reconstruction method based on iterative feedback and attention mechanism
Min LIANG, Jiayi LIU, Jie LI
Journal of Computer Applications    2023, 43 (7): 2280-2287.   DOI: 10.11772/j.issn.1001-9081.2022060877
Abstract276)   HTML7)    PDF (3427KB)(139)       Save

To address the difficulties in reconstructing high-frequency information in image super-resolution reconstruction due to the lack of dependency between low-resolution and high-resolution images and the lack of order during the reconstruction of feature map, a single-image super-resolution reconstruction method based on iterative feedback and attention mechanism was proposed. Firstly, high- and low-frequency information in the image was extracted respectively by using frequency decomposition block, and the two kinds of information was processed respectively, so that the network focused on the extracted high-frequency details to increase the restoration ability of the method on image details. Secondly, through the channel-wise attention mechanism, the reconstruction focus was put on the feature channels with effective features to improve the network ability of extracting the feature map information. Thirdly, the iterative feedback idea was adopted to increase quality of the restored image in the process of repeated comparison and reconstruction. Finally, the output image was generated through the reconstruction block. The proposed method shows better performance in comparison with mainstream super-resolution methods in the 2×, 4× and 8× experiments on Set5, Set14, BSD100, Urban100 and Manga109 benchmark datasets. In the 8× experiments on Manga109 dataset, the proposed method improves Peak Signal-to-Noise Ratio (PSNR) by about 3.01 dB and 2.32 dB averagely and respectively compared to the traditional interpolation method and the Super-Resolution Convolutional Neural Network (SRCNN). Experimental results show that the proposed method can reduce the errors in the reconstruction process and effectively reconstruct finer high-resolution images.

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Compact constraint analysis of SPONGENT S-box based on mixed integer linear programming model
Yipeng SHI, Jie LIU, Jinyuan ZU, Tao ZHANG, Guoqun ZHANG
Journal of Computer Applications    2023, 43 (5): 1504-1510.   DOI: 10.11772/j.issn.1001-9081.2022040496
Abstract327)   HTML5)    PDF (503KB)(109)       Save

Applying the compact constraint calculation method of S-box based on Mixed Integer Linear Programming (MILP) model can solve the low efficiency of differential path search of SPONGENT in differential cryptanalysis. To find the best description of S box, a compactness verification algorithm was proposed to verify the inequality constraints in S-box from the perspective of the necessity of the existence of constraints. Firstly, the MILP model was introduced to analyze the inequality constraints of SPONGENT S-box, and the constraint composed of 23 inequalities was obtained. Then, an index for evaluating the existence necessity of constraint inequality was proposed, and a compactness verification algorithm for verifying the compactness of group of constraint inequalities was proposed based on this index. Finally, the compactness of the obtained SPONGENT S-box constraint was verified by using the proposed algorithm. Calculation analysis show that the 23 inequalities have a unique impossible difference mode that can be excluded, that is, each inequality has the necessity of existence. Furthermore, for the same case, the number of inequalities was reduced by 20% compared to that screened by using the greedy algorithm principle. Therefore, the obtained inequality constraint of S-box in SPONGENT is compact, and the proposed compactness verification algorithm outperforms the greedy algorithm.

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Aspect-oriented fine-grained opinion tuple extraction with adaptive span features
Linying CHEN, Jianhua LIU, Shuihua SUN, Zhixiong ZHENG, Honghui LIN, Jie LIN
Journal of Computer Applications    2023, 43 (5): 1454-1460.   DOI: 10.11772/j.issn.1001-9081.2022040502
Abstract280)   HTML4)    PDF (1182KB)(226)       Save

Aspect-oriented Fine-grained Opinion Extraction (AFOE) extracts aspect terms and opinion terms from reviews in the form of opinion pairs or additionally extracts sentiment polarities of aspect terms on the basis of the above to form opinion triplets. Aiming at the problem of neglecting correlation between the opinion pairs and contexts, an aspect-oriented Adaptive Span Feature-Grid Tagging Scheme (ASF-GTS) model was proposed. Firstly, BERT (Bidirectional Encode Representation from Transformers) model was used to obtain the feature representation of the sentence. Then, the correlation between the opinion pair and local context was enhanced by the Adaptive Span Feature (ASF) method. Next, Opinion Pair Extraction (OPE) was transformed into a uniform grid tagging task by Grid Tagging Scheme (GTS). Finally, the corresponding opinion pairs or opinion triplet were generated by the specific decoding strategy. Experiments were carried out on four AFOE benchmark datasets adaptive to the task of opinion tuple extraction. The results show that compared with GTS-BERT (Grid Tagging Scheme-BERT) model, the proposed model has the F1-score improved by 2.42% to 7.30% and 2.62% to 6.61% on opinion pair or opinion triplet tasks, respectively. The proposed model can effectively reserve the sentiment correlation between opinion pair and context, and extract opinion pairs and their sentiment polarities more accurately.

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Poisoning attack toward visual classification model
Jie LIANG, Xiaoyan HAO, Yongle CHEN
Journal of Computer Applications    2023, 43 (2): 467-473.   DOI: 10.11772/j.issn.1001-9081.2021122068
Abstract582)   HTML21)    PDF (3264KB)(259)       Save

In data poisoning attacks, backdoor attackers manipulate the distribution of training data by inserting the samples with hidden triggers into the training set to make the test samples misclassified so as to change model behavior and reduce model performance. However, the drawback of the existing triggers is the sample independence, that is, no matter what trigger mode is adopted, different poisoned samples contain the same triggers. Therefore, by combining image steganography and Deep Convolutional Generative Adversarial Network (DCGAN), an attack method based on sample was put forward to generate image texture feature maps according to the gray level co-occurrence matrix, embed target label character into the texture feature maps as a trigger by using the image steganography technology, and combine texture feature maps with trigger and clean samples into poisoned samples. Then, a large number of fake pictures with trigger were generated through DCGAN. In the training set samples, the original poisoned samples and the fake pictures generated by DCGAN were mixed together to finally achieve the effect that after the poisoner injecting a small number of poisoned samples, the attack rate was high and the effectiveness, sustainability and concealment of the trigger were ensured. Experimental results show that this method avoids the disadvantages of sample independence and has the model accuracy reached 93.78%. When the proportion of poisoned samples is 30%, data preprocessing, pruning defense and AUROR defense have the least influence on the success rate of attack, and the success rate of attack can reach about 56%.

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Fundus vessel segmentation method based on U-Net and pulse coupled neural network with adaptive threshold
Guangzhu XU, Wenjie LIN, Sha CHEN, Wan KUANG, Bangjun LEI, Jun ZHOU
Journal of Computer Applications    2022, 42 (3): 825-832.   DOI: 10.11772/j.issn.1001-9081.2021040856
Abstract435)   HTML18)    PDF (1357KB)(191)       Save

Due to the complex and variable structure of fundus vessels, and the low contrast between the fundus vessel and the background, there are huge difficulties in segmentation of fundus vessels, especially small fundus vessels. U-Net based on deep fully convolutional neural network can effectively extract the global and local information of fundus vessel images,but its output is grayscale image binarized by a hard threshold, which will cause the loss of vessel area, too thin vessel and other problems. To solve these problems, U-Net and Pulse Coupled Neural Network (PCNN) were combined to give play to their respective advantages and design a fundus vessel segmentation method. First, the iterative U-Net model was used to highlight the vessels, the fusion results of the features extracted by the U-Net model and the original image were input again into the improved U-Net model to enhance the vessel image. Then, the U-Net output result was viewed as a gray image, and the PCNN with adaptive threshold was utilized to perform accurate vessel segmentation. The experimental results show that the AUC (Area Under the Curve) of the proposed method was 0.979 6,0.980 9 and 0.982 7 on the DRVIE, STARE and CHASE_DB1 datasets, respectively. The method can extract more vessel details, and has strong generalization ability and good application prospects.

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Stock trend prediction method based on temporal hypergraph convolutional neural network
Xiaojie LI, Chaoran CUI, Guangle SONG, Yaxi SU, Tianze WU, Chunyun ZHANG
Journal of Computer Applications    2022, 42 (3): 797-803.   DOI: 10.11772/j.issn.1001-9081.2021050748
Abstract1564)   HTML66)    PDF (742KB)(850)       Save

Traditional stock prediction methods are mostly based on time-series models, which ignore the complex relations among stocks, and the relations often exceed pairwise connections, such as stocks in the same industry or multiple stocks held by the same fund. To solve this problem, a stock trend prediction method based on temporal HyperGraph Convolutional neural Network (HGCN) was proposed, and a hypergraph model based on financial investment facts was constructed to fit multiple relations among stocks. The model was composed of two major components: Gated Recurrent Unit (GRU) network and HGCN. GRU network was used for performing time-series modeling on historical data to capture long-term dependencies. HGCN was used to model high-order relations among stocks to learn intrinsic relation attributes, and introduce the multiple relation information among stocks into traditional time-series modeling for end-to-end trend prediction. Experiments on real dataset of China A-share market show that compared with existing stock prediction methods, the proposed model improves prediction performance, e.g. compared with the GRU network, the proposed model achieves the relative increases in ACC and F1_score of 9.74% and 8.13%, respectively, and is more stable. In addition, the simulation back-testing results show that the trading strategy based on the proposed model is more profitable, with an annual return of 11.30%, which is 5 percentage points higher than that of Long Short-Term Memory (LSTM) network.

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Influence of channel on formant of vowel in Chinese mandarin
Yijie LIU, Jiangchun LI, Weina CHEN, Qihan HUANG
Journal of Computer Applications    2022, 42 (12): 3906-3912.   DOI: 10.11772/j.issn.1001-9081.2021101816
Abstract363)   HTML2)    PDF (2395KB)(45)       Save

Aiming at the problem of influence of the channel on the characteristics of the vowel formant, a systematic experiment was carried out. Firstly, the standard recordings of 8 volunteers were collected. Then, the standard recordings were played with the mouth simulator, and 104 channel recordings were recorded using 13 different channels. Finally, the characteristic voice segments were extracted, and chi-square test analysis was used in the qualitative analysis of the spectral characteristics, and one-sample t-test was used in the quantitative analysis of acoustic parameters. The statistical results show that about 69% of the channels have a significant influence on the overall form of the high-order formants, and about 85% of the channels have significant differences in the relative intensity of the formants. The one-sample t-test results show that there is no significant difference between the standard recordings and the channel recordings in center frequency of the formant. Experimental results show that the frequency characteristics of formants should be paid more attention to when processing the identification of voices in different channels.

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Structure-fuzzy multi-class support vector machine algorithm based on pinball loss
Kai LI, Jie LI
Journal of Computer Applications    2021, 41 (11): 3104-3112.   DOI: 10.11772/j.issn.1001-9081.2021010062
Abstract700)   HTML40)    PDF (816KB)(339)       Save

The Multi-Class Support Vector Machine (MSVM) has the defects such as strong sensitivity to noise, instability to resampling data and lower generalization performance. In order to solve the problems, the pinball loss function, sample fuzzy membership degree and sample structural information were introduced into the Simplified Multi-Class Support Vector Machine (SimMSVM) algorithm, and a structure-fuzzy multi-class support vector machine algorithm based on pinball loss, namely Pin-SFSimMSVM, was proposed. Experimental results on synthetic datasets, UCI datasets and UCI datasets adding different proportions of noise show that, the accuracy of the proposed Pin-SFSimMSVM algorithm is increased by 0~5.25 percentage points compared with that of SimMSVM algorithm. The results also show that the proposed algorithm not only has the advantages of avoiding indivisible areas of multi-class data and fast calculation speed, but also has good insensitivity to noise and stability to resampling data. At the same time, the proposed algorithm considers the fact that different data samples play different roles in classification and the important prior knowledge contained in the data, so that the classifier training is more accurate.

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Mining multiple sequential patterns with gap constraints
WANG Huadong YANG Jie LI Yajuan
Journal of Computer Applications    2014, 34 (9): 2612-2616.   DOI: 10.11772/j.issn.1001-9081.2014.09.2612
Abstract273)      PDF (913KB)(606)       Save

For the given multiple sequences, a certain threshold and the gap constraints, the study objective is to discover frequent patterns whose supports in multiple sequences are no less than the given threshold value, where any two successive elements of pattern fulfill the user-specified gap constraints, and any two occurrences of a pattern in a given sequence meet the one-off condition. To solve this problem, the existing algorithms only consider the first occurrence of each character of a pattern when they compute the support of a pattern in a given sequence, so that many frequent patterns are not mined. An efficient mining algorithm of multiple sequential patterns with gap constraints, named MMSP, was proposed. Firstly, it stored the candidate positions of a pattern using two-dimensional table, then it selected the position from the candidate positions according to the left-most strategy. The experiments were conducted on DNA sequences. The number of frequent patterns mined by MMSP was 3.23 times of that mined by the related algorithm named M-OneOffMine when the number of multiple sequence elements is constant and the sequence length changes, and the average number of mining patterns by MMSP was 4.11 times of that mined by M-OneOffMine when the number of multiple sequence elements changes. The average number of mined patterns by MMSP was 2.21 and 5.24 times of that mined by M-OneOffMine and MPP respectively when the number of multiple sequence elements changes, and the frequent patterns mined by M-OneOffMine was a subset of MMSP. The experimental results show that MMSP can mine more frequent patterns with shorter time, and it is more suitable for practical applications.

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Application of gray cumulative projection histogram in detection of tire crown crack
Han Yanbin WANG Jie XIA Yingjie LI Jinping
Journal of Computer Applications    2014, 34 (8): 2221-2226.   DOI: 10.11772/j.issn.1001-9081.2014.08.2221
Abstract397)      PDF (950KB)(460)       Save

For automatic detection of tire crown cord overlap defect, a detection method based on the crown X ray image was presented. Firstly, the gray cumulative projection curves that X-ray image was projected along different angles were obtained. Secondly, the local peak energy distribution of curves were calculated and the energy feature vector was constructed by the n largest peak energy values. Thirdly, the tire crown crack image was recognized by the maximum projection curve which could be distinguished through the energy feature vector by Support Vector Machine (SVM). Lastly, using the position inverse calculation, the tire crown crack was located. The experimental results demonstrate that the proposed approach was effective to detect the defects of tire crown which caused by tire cord overlap. The highest rate of correct detection can reach 97.7% in the 1000 crown images collected by the process of production.

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Multi-label classification based on singular value decomposition-partial least squares regression
MA Zongjie LIU Huawen
Journal of Computer Applications    2014, 34 (7): 2058-2060.   DOI: 10.11772/j.issn.1001-9081.2014.07.2058
Abstract222)      PDF (581KB)(518)       Save

To tackle multi-label data with high dimensionality and label correlations, a multi-label classification approach based on Singular Value Decomposition (SVD)-Partial Least Squares Regression (PLSR) was proposed, which aimed at performing dimensionality reduction and regression analysis. Firstly, the label space was taken into a whole so as to exploit the label correlations. After that, the score vectors of both the instance space and label space were obtained by SVD, which was used for dimensionality reduction. Finally, the model of multi-label classification was established based on PLSR. The experiments performed on four real data sets with higher dimensionality verify the effectiveness of the proposed method.

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Parallel algorithm of polygon topology validation for simple feature model
REN Yibin CHEN Zhenjie LI Feixue ZHOU Chen YANG Liyun
Journal of Computer Applications    2014, 34 (7): 1852-1856.   DOI: 10.11772/j.issn.1001-9081.2014.07.1852
Abstract211)      PDF (789KB)(489)       Save

Methods of parallel computation are used in validating topology of polygons stored in simple feature model. This paper designed and implemented a parallel algorithm of validating topology of polygons stored in simple feature model. The algorithm changed the master-slave strategy based on characteristics of topology validation and generated threads in master processor to implement task parallelism. Running time of computing and writing topology errors was hidden in this way. MPI and PThread were used to achieve the combination of processes and threads. The land use data of 5 cities in Jiangsu, China, was used to check the performance of this algorithm. After testing, this parallel algorithm is able to validate topology of massive polygons stored in simple feature model correctly and efficiently. Compared with master-slave strategy, the speedup of this algorithm increases by 20%.

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Improved image denoising algorithm using UK-flag shaped anisotropic diffusion model
ZHAI Donghai YU Jiang DUAN Weixia XIAO Jie LI Fan
Journal of Computer Applications    2014, 34 (5): 1494-1498.   DOI: 10.11772/j.issn.1001-9081.2014.05.1494
Abstract322)      PDF (836KB)(365)       Save

To effectively improve the denoising effect of the original anisotropic diffusion model that used only the 4 neighborhood pixels information and ignored the diagonal neighborhood pixels information of the pixel to be repaired in the image denoising process, a image denoising algorithm using UK-flag shaped anisotropic diffusion model was proposed. This model not only made full use of the reference information of the 4 neighborhood pixels as in original algorithm, but also used another 4 diagonal neighborhood pixels information in the denoising process. Then the model using the 8 direction pixels information for image denoising was presented, and it was proved to be rational. The proposed algorithm, the original algorithm, and an improved similar algorithm were used to remove the noise from 4 images with noise. The experimental results show that the proposed algorithm has an average increase of 1.90dB and 1.43dB in Peak Signal-to-Noise Ratio (PSNR) value respectively, and an average increase of 0.175 and 0.1 in Mean Structure Similitary Index (MSSIM) value respectively, compared with the original algorithm and the improved similar algorithm, which concludes that the proposed algorithm is more suitable for image denoising. algorithm not only made full use of the reference information of the 4 neighborhood pixels as in original algorithm, but also another 4 diagonal neighborhood pixels information was used in the denoising process, and the algorithm was proved to be rationality. The experimental results showed that the proposed algorithm could increase the PSNR (peak signal-to-noise ratio) value 1.69db, and the MSSIM(mean structure similitary index) value 0.14, compared with the other similar algorithms in image denoising, which conclud that this proposed algorithm is more suitable for image denoising.

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Behavior modeling of transport robot using Petri nets
YUAN Jie LI Wei
Journal of Computer Applications    2014, 34 (5): 1360-1363.   DOI: 10.11772/j.issn.1001-9081.2014.05.1360
Abstract355)      PDF (774KB)(518)       Save

New difficulties are met when establishing accurate behavioral models of a transport robot. To solve this problem, behavioral models of a transport robot were built using Petri Nets (PN) with inhibitor arcs. There exist coupling, constraint, and asynchronization relationships among the behaviors of a transport robot. A Petri net metamodel with inhibitor arcs of interactive behaviors as well as a token flow control mechanism were utilized for modeling the behaviors of a transport robot. The Petri net models were converted into LabVIEW programs using LabVIEW2012 and the Robotics module. The robot behaviors were verified using a transport robot platform. The experimental results demonstrate that the transport robot's behaviors and interaction logic are achieved, and that the robot has behavioral identification, decision-making and implementation capabilities, and it is a suitable method model the behaviors of a transport robot using Petri nets with inhibitor arcs. The reference models of Petri nets are given for designing related behaviors of transport robots.

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Sentiment analysis on Web financial text based on semantic rules
WU Jiang TANG Chang-jie LI Taiyong CUI Liang
Journal of Computer Applications    2014, 34 (2): 481-485.  
Abstract939)      PDF (922KB)(1632)       Save
In order to effectively improve the accuracy of sentiment orientation and intensity analysis of unstructured Web financial text, a sentiment analysis algorithm for Web financial text based on semantic rule (SAFT-SR) was proposed. The algorithm extracted features of financial text based on Apriori, constructed financial sentiment lexicon and semantic rules to recognize sentiment unit and intensity, and figured out the sentiment orientation and intensity of text. Experiment results demonstrate that SAFT-SR is a promising algorithm for sentiment analysis on financial text. Compared with Ku’s algorithm, in sentiment orientation classification, SAFT-SR has better classification performance and increases F-measure, recall and precision; in sentiment intensity analysis, SAFT-SR reduces error and is closer to expert mark.
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Personalization recommendation algorithm for Web resources based on ontology
LIANG Junjie LIU Qiongni YU Dunhui
Journal of Computer Applications    2014, 34 (11): 3135-3139.   DOI: 10.11772/j.issn.1001-9081.2014.11.3135
Abstract296)      PDF (752KB)(624)       Save

To improve the accuracy of recommended Web resources, a personalized recommendation algorithm based on ontology, named BO-RM, was proposed. Subject extraction and similarity measurement methods were designed, and ontology semantic was used to cluster Web resources. With a user's browser tracks captured, the tendency of preferences and recommendation were adjusted dynamically. Comparison experiments with collaborative filtering algorithm based on situation named CFR-RM and personalized prediction algorithm based on model were given. The results show that BO-RM has relatively stable overhead time and good performance in Mean Reciprocal Rank (MRR) and Mean Average Precision (MAP). The results prove that BO-RM improves the efficiency by using offline data analysis for large Web resources, thus it is practical. In addition, BO-RM captures the users' interest in real-time to updates the recommendation list dynamically, which meets the real needs of users.

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Graph embedding method integrated multiscale features
LI Zhijie LI Changhua YAO Peng LIU Xin
Journal of Computer Applications    2014, 34 (10): 2891-2894.   DOI: 10.11772/j.issn.1001-9081.2014.10.2891
Abstract210)      PDF (797KB)(305)       Save

In the domain of structural pattern recognition, the existing graph embedding methods lack versatility and have high computation complexity. A new graph embedding method integrated with multiscale features based on space syntax theory was proposed to solve this problem. This paper extracted the global, local and detail features to construct feature vector depicting the graph feature by multiscale histogram. The global features included vertex number, edge number, and intelligible degree. The local features referred to node topological feature, edge domain features dissimilarity and edge topological features dissimilarity. The detail features comprised numerical and symbolic attributes on vertex and edge. In this way, the structural pattern recognition was converted into statistical pattern recognition, thus Support Vector Machine (SVM) could be applied to achieve graph classification. The experimental results show that the proposed graph embedding method can achieve higher classifying accuracy in different graph datasets. Compared with other graph embedding methods, the proposed method can adequately render the graphs topology, merge the non-topological features in terms of the graphs domain property, and it has a favorable universality and low computation complexity.

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Discrete free search algorithm
GUO Xin SUN Lijie LI Guangming JIANG Kaizhong
Journal of Computer Applications    2013, 33 (06): 1563-1570.   DOI: 10.3724/SP.J.1087.2013.01563
Abstract699)      PDF (572KB)(686)       Save
A free search algorithm was proposed for the discrete optimization problem. However,solutions simply got from free search algorithm often have crossover phenomenon. Then, an algorithm free search algorithm combined with cross elimination was put forward, which not only greatly improved the convergence rate of the search process but also enhanced the quality of the results. The experimental results using Traveling Saleman Problem (TSP) standard data show that the performance of the proposed algorithm increases by about 1.6% than that of the genetic algorithm.
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User permission isolation model based on finite state machine
LI Jianjun JIANG Yixiang QIAN Jie LI Wei LI Yu
Journal of Computer Applications    2013, 33 (01): 149-152.   DOI: 10.3724/SP.J.1087.2013.00149
Abstract947)      PDF (645KB)(644)       Save
For privilege escalation problem in operating system, a user permission isolation model based on Finite State Machine (FSM) was proposed in this paper, which depicted the users' permissions as a FSM. A user's permission was mapped to a FSM, which was able to distinguish the legality of user's operation sequence. Besides, the model proved that it easily leaded to permission escalation at the shared permission points. Ultimately, through FSM, the model achieves effective identification and judgment of user permissions isolation.
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Group path planning method based on improved group search optimization algorithm
ZHENG Hui-jie LIU Hong ZHENG Xiang-wei
Journal of Computer Applications    2012, 32 (08): 2223-2226.   DOI: 10.3724/SP.J.1087.2012.02223
Abstract1204)      PDF (608KB)(430)       Save
Concerning the problems that traditional path planning of group animation needs long time for searching and is of poor optimization, the authors proposed a multi-threaded path planning algorithm based on group search optimization. Firstly, to solve the problem that the algorithm easily gets trapped in local optimum, metroplis rule was introduced in this search mode. Secondly, by using random path through the multi-threading and stitching techniques, the algorithm was applied to path planning. The simulation results show that the algorithm has better global convergence both in high-dimensional and low-dimensional cases, and the method is good enough to meet the requirements of path planning in complex animation environment.
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RFID anti-collision algorithm based on novel jumping and dynamic searching
FENG Na PAN Wei-jie LI Shao-bo YANG Guan-ci
Journal of Computer Applications    2012, 32 (01): 288-291.   DOI: 10.3724/SP.J.1087.2012.00288
Abstract1290)      PDF (636KB)(692)       Save
The paper briefly introduced the merits and shortcomings of the existing anti-collision algorithms. Based on the idea of Jumping and Dynamic Searching (JDS) algorithm, a Novel JDS (NJDS) algorithm for tags' anti-collision was proposed. The algorithm brought stack into the new jumping before and after searching strategy to reduce the number of collision slots and avoid idle slots. When requested by readers, it adopted dynamic transmission and variable length adjustment strategy, and used the known information remembered by the feedback tags' information to identify the unknown data bits of tags, which reduced the number of search of readers and the transmission of system. The analysis on simulation results indicates that the proposed algorithm performs significantly better than the existing anti-collision algorithms. The transmission is greatly reduced, and throughput of the system has increased significantly.
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3D simulation of bending tree branch and fractal tree root
ZHANG Jie LIN Bin CAI Wenqi XIE Zhuangrong
Journal of Computer Applications    2011, 31 (06): 1703-1705.   DOI: 10.3724/SP.J.1087.2011.01703
Abstract1533)      PDF (598KB)(580)       Save
The shape of a tree is mostly determined by the reality to the nature layout of branches. In order to simulate a 3D tree branch to mimic the natural tree shape, using the theory of fractal algorithm and mechanics of material, a simulating method for the 3D's bending branch and fractal root based on the gravity field was proposed. The stress state of the branch was reflected by its bending degree. Bending degree could be controlled by changing the value of Young's modulus. Also, with X3D and Java, fractal algorithm combined with Extrusion node of X3D was used to simulate the geotropism of the bending root. A realistic 3D tree can be easily created with some input data using our simulation. By using the close relationship of the tree's underground part and upper part, a simulation method of gravity's effect on the tree shape was established. The experimental results show that the method can easily generate realistic three-dimensional form of fractal trees.
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