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Semi-supervised three-way clustering ensemble based on Seeds set and pairwise constraints
Chunmao JIANG, Peng WU, Zhicong LI
Journal of Computer Applications    2023, 43 (5): 1481-1488.   DOI: 10.11772/j.issn.1001-9081.2022071094
Abstract192)   HTML5)    PDF (1442KB)(77)       Save

Using appropriate strategies, clustering ensemble can effectively improve the stability, robustness and precision of clustering results by fusing multiple base cluster members with differences. Current research on the clustering ensemble rarely uses known priori information, and it is difficult to describe belonging relationships between objects and clusters when facing complex data. Therefore, a semi-supervised three-way clustering ensemble method was proposed on the basis of Seeds set and pairwise constraints. Firstly, based on the existing label information, a new three-way label propagation algorithm was proposed to construct the base cluster members. Secondly, a semi-supervised three-way clustering ensemble framework was designed to integrate the base cluster members to construct a consistent similarity matrix, and this matrix was optimized by using pairwise constraint information. Finally, the three-way spectral clustering was employed as a consistency function to cluster the similarity matrix to obtain the final clustering results. Experimental results on several real datasets in UCI show that compared with the semi-supervised clustering ensemble algorithms including Cluster-based Similarity Partitioning Algorithm (CSPA), HyperGraph Partitioning Algorithm (HGPA), Meta-CLustering Algorithm (MCLA), Label Propagation Algorithm (LPA) and Cop-Kmeans, the proposed method achieves the best results on most of the datasets in terms of Normalized Mutual Information (NMI), Adjusted Rand Index (ARI) and F-measure.

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Parking space detection method based on self-supervised learning HOG prediction auxiliary task
Lei LIU, Peng WU, Kai XIE, Beizhi CHENG, Guanqun SHENG
Journal of Computer Applications    2023, 43 (12): 3933-3940.   DOI: 10.11772/j.issn.1001-9081.2022111687
Abstract138)   HTML3)    PDF (2364KB)(132)       Save

In the intelligent parking space management system, a decrease in accuracy and effectiveness of parking space prediction can be caused by factors such as illumination changes and parking space occlusion. To overcome this problem, a parking space detection method based on self-supervised learning HOG (Histogram of Oriented Gradient) prediction auxiliary task was proposed. Firstly, a self-supervised learning auxiliary task to predict the HOG feature in occluded part of image was designed, the visual representation of the image was learned more fully and the feature extraction ability of the model was improved by using the MobileViTBlock (light-weight, general-purpose, and Mobile-friendly Vision Transformer Block) to synthesize the global information of the image. Then, an improvement was made to the SE (Squeeze-and-Excitation) attention mechanism, thereby enabling the model to achieve or even exceed the effect of the original SE attention mechanism at a lower computational cost. Finally, the feature extraction part trained by the auxiliary task was applied to the downstream classification task for parking space status prediction. Experiments were carried out on the mixed dataset of PKLot and CNRPark. The experimental results show that the proposed model has the accuracy reached 97.49% on the test set; compared to RepVGG, the accuracy of occlusion prediction improves by 5.46 percentage points, which represents a great improvement compared with other parking space detection algorithms.

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Improved rectangle NAM algorithm for image representation
Peng WU Hou-quan XU Chuan-bo CHEN Guang-yue LU Kai XIE
Journal of Computer Applications    2011, 31 (04): 1016-1018.   DOI: 10.3724/SP.J.1087.2011.01016
Abstract1441)      PDF (689KB)(375)       Save
In order to improve image representation efficiency, an improved rectangle Non-symmetry Anti-packing representation Model (NAM) named IRNAM was proposed for image coding. This scheme adopted double-rectangle sub-patterns to represent gray image, integrated bit plane optimization strategy and stored the sub-patterns continuously, thus the number of sub-patterns had decreased sharply. The experimental results show that compared with rectangle NAM algorithm and other improved NAM algorithms, the number of sub-patterns can be reduced apparently after employing IRNAM algorithm, which can save data storage space effectively and prove to be a high performance image representation method.
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