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Robust algorithm for extracting skin pigment concentration
from color image
Xu Shu-chang, ZHANG San-yuan, ZHANG Yin
J4    2011, 45 (2): 253-258.   DOI: 10.3785/j.issn.1008-973X.2011.02.010
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To investigate the two most important pigments of human, melanin and hemoglobin, an image-channel-difference of optical density space based algorithm was proposed for automatically extracting melanin and hemoglobin concentration distribution map from single color image. The algorithm built mathematic model between pigment and digital image based on theoretical foundation of skin structure and its optical property. The input image firstly was divided into several sub-regions. Independent component analysis (ICA) technology was performed in every sub-region to calculate Separation Vector, which is successively verified by specified rules. All the valid Separation Vectors were then re-combined to form new vectors, from which the final separation vector with minimal deviation is selected. The pigment concentration distribution maps were displayed after obtaining the final global separation vector. The experiments show the effectiveness and great robustness of the proposed algorithm.

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Iterative optimization method for injection parameters based on
surrogate model
ZHAO Peng, FU Jian-zhong, LI Yang, CUI Shu-biao
J4    2011, 45 (2): 197-200.   DOI: 10.3785/j.issn.1008-973X.2011.02.001
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Cavity pressure and temperature difference are two important quality criteria. Considering that most injection molded parts have a sheet like geometry, a fast strip analysis model based on mechanics equations for viscous fluid, was adopted as a surrogate model to approximate the time-consuming computer simulation software for predicating the above quality criteria. According to the predicted quality criteria, a particle swarm optimization algorithm was employed to find out the optimum injection parameters. The proposed optimization method can optimize the injection parameters in short time and it does not rely on any knowledge of molding process. Finally, two experiments were employed to validate the surrogate model and the proposed optimization method. Experimental results show that the cavity pressure predicted by the surrogate model agree well with the experimental data, with the relative error being less than 8.41%, and the results of the proposed optimization method are nearly identical to that of response surface method, while the required time of the proposed method is only 0.02% of that of response surface method.

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Compound fault decoupling diagnosis method based on improved Transformer
Yu-xiang WANG,Zhi-wei ZHONG,Peng-cheng XIA,Yi-xiang HUANG,Cheng-liang LIU
Journal of ZheJiang University (Engineering Science)    2023, 57 (5): 855-864.   DOI: 10.3785/j.issn.1008-973X.2023.05.001
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Most of the compound fault diagnosis methods regard the compound fault as a new single fault type, ignoring the interaction of internal single faults, and the fault analysis is vague in granularity and poor in interpretation. An improved Transformer-based compound fault decoupling diagnosis method was proposed for industrial environments with very little compound fault data. The diagnosis process included pre-processing, feature extraction and fault decoupling. With introducing the decoder of the Transformer, the cross-attention mechanism enables each single fault label to adaptively in the extracted feature layer focus on the discriminative feature region corresponding to the fault feature and predicts the output probability to achieve compound fault decoupling. Compound fault tests were designed to verify the effectiveness of the method compared with the advanced algorithms. The results showed that the proposed method had high diagnostic accuracy with a small number of single fault training samples and a very small number of compound fault training samples. The compound fault diagnosis accuracy reached 88.29% when the training set contained only 5 compound fault samples. Thus the new method has a significant advantage over other methods.

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Surface defect detection algorithm of electronic components based on improved YOLOv5
Yao ZENG,Fa-qin GAO
Journal of ZheJiang University (Engineering Science)    2023, 57 (3): 455-465.   DOI: 10.3785/j.issn.1008-973X.2023.03.003
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For the poor real-time detection capability of the current object detection model in the production environment of electronic components, GhostNet was used to replace the backbone network of YOLOv5. And for the existence of small objects and objects with large scale changes on the surface defects of electronic components, a coordinate attention module was added to the YOLOv5 backbone network, which enhanced the sensory field while avoiding the consumption of large computational resources. The coordinate information was embedded into the channel attention to improve the object localization of the model. The feature pyramid networks (FPN) structure in the YOLOv5 feature fusion module was replaced with a weighted bi-directional feature pyramid network structure, to enhance the fusion capability of multi-scale weighted features. Experimental results on the self-made defective electronic component dataset showed that the improved GCB-YOLOv5 model achieved an average accuracy of 93% and an average detection time of 33.2 ms, which improved the average accuracy by 15.0% and the average time by 7 ms compared with the original YOLOv5 model. And the improved model can meet the requirements of both accuracy and speed of electronic component surface defect detection.

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Multi-agent pursuit and evasion games based on improved reinforcement learning
Ya-li XUE,Jin-ze YE,Han-yan LI
Journal of ZheJiang University (Engineering Science)    2023, 57 (8): 1479-1486.   DOI: 10.3785/j.issn.1008-973X.2023.08.001
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A multi-agent reinforcement learning algorithm based on priority experience replay and decomposed reward function was proposed in multi-agent pursuit and evasion games. Firstly, multi-agent twin delayed deep deterministic policygradient algorithm (MATD3) algorithm based on multi-agent deep deterministic policy gradient algorithm (MADDPG) and twin delayed deep deterministic policy gradient algorithm (TD3) was proposed. Secondly, the priority experience replay was proposed to determine the priority of experience and sample the experience with high reward, aiming at the problem that the reward function is almost sparse in the multi-agent pursuit and evasion problem. In addition, a decomposed reward function was designed to divide multi-agent rewards into individual rewards and joint rewards to maximize the global and local rewards. Finally, a simulation experiment was designed based on DEPER-MATD3. Comparison with other algorithms showed that DEPER-MATD3 algorithm solved the over-estimation problem, and the time consumption was improved compared with MATD3 algorithm. In the decomposed reward function environment, the global mean rewards of the pursuers were improved, and the pursuers had a greater probability of chasing the evader.

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Structured image super-resolution network based on improved Transformer
Xin-dong LV,Jiao LI,Zhen-nan DENG,Hao FENG,Xin-tong CUI,Hong-xia DENG
Journal of ZheJiang University (Engineering Science)    2023, 57 (5): 865-874.   DOI: 10.3785/j.issn.1008-973X.2023.05.002
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Most of existing structural image super-resolution reconstruction algorithms can only solve a specific single type of structural image super-resolution problem. A structural image super-resolution network based on improved Transformer (TransSRNet) was proposed. The network used the self-attention mechanism of Transformer mine a wide range of global information in spatial sequences. A spatial attention unit was built by using the hourglass block structure. The mapping relationship between the low-resolution space and the high-resolution space in the local area was concerned. The structured information in the image mapping process was extracted. The channel attention module was used to fuse the features of the self-attention module and the spatial attention module. The TransSRNet was evaluated on highly-structured CelebA, Helen, TCGA-ESCA and TCGA-COAD datasets. Results of evaluation showed that the TransSRNet model had a better overall performance compared with the super-resolution algorithms. With a upscale factor of 8, the PSNR of the face dataset and the medical image dataset could reach 28.726 and 26.392 dB respectively, and the SSIM could reach 0.844 and 0.881 respectively.

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Improved method for blockchain Kademlia network based on small world theory
Yue ZHAO,He ZHAO,Haibo TAN,Bin YU,Wangnian YU,Zhiyu MA
Journal of ZheJiang University (Engineering Science)    2024, 58 (1): 1-9.   DOI: 10.3785/j.issn.1008-973X.2024.01.001
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An improved method for the blockchain Kademlia network based on small world theory was proposed aiming at the issue of sacrificing security to improve scalability in the current research of the blockchain Kademlia network. The idea of the small world theory was followed, and a probability formula for replacing expansion nodes was proposed. The probability was inversely proportional to the distance between nodes. The number of node replacements and additional nodes could be flexibly adjusted according to actual conditions. The theoretical analysis and experimental verification demonstrate that the network transformed by this method can reach a stable state. The experimental results showed that the transmission hierarchy required for broadcasting transaction messages throughout the network was reduced by 15.0% to 30.8% and the rate of locating nodes was increased. The level of network structure was reduced and network security was enhanced compared to other optimization algorithms that modify the network structure.

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Calculation and prediction of flue gas residence time from CFB municipal solid waste incinerator
Xiao-qing LIN,Yu-xuan YING,Hong YU,Xiao-dong LI,Jian-hua YAN
Journal of ZheJiang University (Engineering Science)    2022, 56 (8): 1578-1587.   DOI: 10.3785/j.issn.1008-973X.2022.08.012
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Ensuring that the flue gas in the furnace stays within the temperature range of no less than 850 ℃ for at least 2 s contributes to the steady municipal solid waste (MSW) incineration, and the reduction of secondary pollution. However, at present, it is difficult to quantitatively calculate and predict the residence time of flue gas in the high temperature area by only using the thermocouple for qualitative evaluation. Based on the thermodynamic calculation, correlation analysis of practical operation parameters, and a variety of machine learning algorithms (backpropagation neural network, recurrent neural network, and random forest regression), the residence time of flue gas in high-temperature areas (>850 ℃) was calculated, correlation analysis of key operation parameters was conducted, and the prediction model of residence time was constructed, aiming at a typical MSW circulating fluidized bed boiler in China. Results revealed that 10 key operating parameters, e.g. section temperature of the furnace, temperature and pressure of primary air and secondary air, etc., had a strong correlation and predictability with the high-temperature flue gas residence time. Moreover, the model of the recurrent neural network was relatively optimal, with a higher fitting degree and accuracy. Specifically, the mean square error (MSE) was 0.11626, and the average absolute error between the predicted value and real value was 1.174%. Research enabled the prediction of flue gas temperature variation in high-temperature areas, helped optimize the MSW incineration, and contributed to the advanced control of pollutant emission reduction.

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Improved YOLOv3-based defect detection algorithm for printed circuit board
Bai-cheng BIAN,Tian CHEN,Ru-jun WU,Jun LIU
Journal of ZheJiang University (Engineering Science)    2023, 57 (4): 735-743.   DOI: 10.3785/j.issn.1008-973X.2023.04.011
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An AT-YOLO algorithm based on improved YOLOv3 was proposed aiming at the problem that the existing deep learning-based defect detection algorithm for printed circuit boards (PCB) could not meet the accuracy and efficiency requirements at the same time. Feature extraction capabilities were improved and the number of parameters was reduced by replacing the backbone with ResNeSt50. SPP module was added to integrate the features of different receptive fields and enrich the ability of feature representation. The PANet structure was improved to replace FPN, and the SE module was inserted to enhance the expression capability of effective feature maps. A set of high-resolution feature maps were added to the input and output in order to improve the sensitivity to small target objects, and the detection scale was increased from three to four. K-means algorithm was re-used to generate sizes of anchors in order to improve the accuracy of object detection. The experimental results showed that the AT-YOLO algorithm had an AP0.5 value of 98.42%, the number of parameters was 3.523×107, and the average detection speed was 36 frame per second on the PCB defect detection dataset, which met the requirements of accuracy and efficiency.

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Surface water quality prediction model based on graph neural network
Jia-hui XU,Jing-chang WANG,Ling CHEN,Yong WU
Journal of ZheJiang University (Engineering Science)    2021, 55 (4): 601-607.   DOI: 10.3785/j.issn.1008-973X.2021.04.001
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A surface water quality prediction model based on graph neural network (GNN) was proposed to solve the problem that water quality data has complex dependencies in both temporal and spatial dimensions. GNN was utilized to model the complex spatial dependencies of monitoring stations, and long short-term memory (LSTM) was used to model the complex temporal dependencies of historical water quality sequences. Then the encoded vector was input into the decoder to get the water quality prediction output. The experimental results show that the model can achieve 23.3%, 26.6% and 14.8% performance improvements compared with time series analysis methods, general regression methods and existing deep learning methods.

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Driver fatigue state detection method based on multi-feature fusion
Hao-jie FANG,Hong-zhao DONG,Shao-xuan LIN,Jian-yu LUO,Yong FANG
Journal of ZheJiang University (Engineering Science)    2023, 57 (7): 1287-1296.   DOI: 10.3785/j.issn.1008-973X.2023.07.003
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The improved YOLOv5 object detection algorithm was used to detect the facial region of the driver and a multi-feature fusion fatigue state detection method was established aiming at the problem that existing fatigue state detection method cannot be applied to drivers under the epidemic prevention and control. The image tag data including the situation of wearing a mask and the situation without wearing a mask were established according to the characteristics of bus driving. The detection accuracy of eyes, mouth and face regions was improved by increasing the feature sampling times of YOLOv5 model. The BiFPN network structure was used to retain multi-scale feature information, which makes the prediction network more sensitive to targets of different sizes and improves the detection ability of the overall model. A parameter compensation mechanism was proposed combined with face keypoint algorithm in order to improve the accuracy of blink and yawn frame number. A variety of fatigue parameters were fused and normalized to conduct fatigue classification. The results of the public dataset NTHU and the self-made dataset show that the proposed method can recognize the blink and yawn of drivers both with and without masks, and can accurately judge the fatigue state of drivers.

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Review of CO2 direct air capture adsorbents
Tao WANG,Hao DONG,Cheng-long HOU,Xin-ru WANG
Journal of ZheJiang University (Engineering Science)    2022, 56 (3): 462-475.   DOI: 10.3785/j.issn.1008-973X.2022.03.005
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The research progress of direct air capture CO2 adsorbents was reviewed. The advantages and disadvantages of alkali/alkaline metal based adsorbents, metal organic framework adsorbents, amine loaded adsorbents and moisture swing adsorbents were compared. Meanwhile, the properties of adsorbents from the aspects of adsorption capacity and amine efficiency, kinetics and supporters, regeneration mode and energy consumption, thermal stability and resistance to degradation were evaluated. Additionally, the related engineering demonstration projects and economic evaluation were briefly discussed. Finally, the problems existing in the current research were summarized, and the future research direction was prospected.

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Adaptive salp swarm algorithm for solving flexible job shop scheduling problem with transportation time
Hao-yi NIU,Wei-min WU,Ting-qi ZHANG,Wei SHEN,Tao ZHANG
Journal of ZheJiang University (Engineering Science)    2023, 57 (7): 1267-1277.   DOI: 10.3785/j.issn.1008-973X.2023.07.001
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An adaptive salp swarm algorithm was proposed by minimizing the makespan in order to solve the flexible job shop scheduling problem with transportation time. A three-layer coding scheme was designed based on random key in order to make the discrete solution space continuous. The inertia weight was introduced to evaluate the influence among followers in order to enhance the global exploration and local search performance of the algorithm. An adaptive leader-follower population update strategy was proposed, and the number of leaders and followers was adjusted by the population status. The tabu search strategy was combined with the neighborhood search in order to prevent the algorithm from falling into local optimum. The benchmark instances verified the effectiveness and superiority of the proposed algorithm. The influence of the number of AGVs on the makespan conforms to the law of diminishing marginal effect.

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Survey on program representation learning
Jun-chi MA,Xiao-xin DI,Zong-tao DUAN,Lei TANG
Journal of ZheJiang University (Engineering Science)    2023, 57 (1): 155-169.   DOI: 10.3785/j.issn.1008-973X.2023.01.016
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There has been a trend of intelligent development using artificial intelligence technology in order to improve the efficiency of software development. It is important to understand program semantics to support intelligent development. A series of research work on program representation learning has emerged to solve the problem. Program representation learning can automatically learn useful features from programs and represent the features as low-dimensional dense vectors in order to efficiently extract program semantic and apply it to corresponding downstream tasks. A comprehensive review to categorize and analyze existing research work of program representation learning was provided. The mainstream models for program representation learning were introduced, including the frameworks based on graph structure and token sequence. Then the applications of program representation learning technology in defect detection, defect localization, code completion and other tasks were described. The common toolsets and benchmarks for program representation learning were summarized. The challenges for program representation learning in the future were analyzed.

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Multi-target tracking of vehicles based on optimized DeepSort
Li-sheng JIN,Qiang HUA,Bai-cang GUO,Xian-yi XIE,Fu-gang YAN,Bo-tao WU
Journal of ZheJiang University (Engineering Science)    2021, 55 (6): 1056-1064.   DOI: 10.3785/j.issn.1008.973X.2021.06.005
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A front multi-vehicle target tracking algorithm optimized by DeepSort was proposed in order to improve the awareness of autonomous vehicles to the surrounding environment. Gaussian YOLO v3 model was adopted as the front-end target detector, and training was based on DarkNet-53 backbone network. Gaussian YOLO v3-Vehicle, a detector specially designed for vehicles was obtained, which improved the vehicle detection accuracy by 3%. The augmented VeRi data set was proposed to conduct the re-recognition pre-training in order to overcome the shortcomings that the traditional pre-training model doesn't target vehicles. A new loss function combining the central loss function and the cross entropy loss function was proposed, which can make the target features extracted by the network become better in-class aggregation and inter-class resolution. Actual road videos in different environments were collected in the test part, and CLEAR MOT evaluation index was used for performance evaluation. Results showed a 1% increase in tracking accuracy and a 4% reduction in identity switching times compared with the benchmark DeepSort YOLO v3.

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New method for news recommendation based on Transformer and knowledge graph
Li-zhou FENG,Yang YANG,You-wei WANG,Gui-jun YANG
Journal of ZheJiang University (Engineering Science)    2023, 57 (1): 133-143.   DOI: 10.3785/j.issn.1008-973X.2023.01.014
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A news recommendation method based on Transformer and knowledge graph was proposed to increase the auxiliary information and improve the prediction accuracy. The self-attention mechanism was used to obtain the connection between news words and news entities in order to combine news semantic information and entity information. The additive attention mechanism was employed to capture the influence of words and entities on news representation. Transformer was introduced to pick up the correlation information between clicked news of user and capture the change of user interest over time by considering the time-series characteristics of user preference for news. High-order structural information in knowledge graphs was used to fuse adjacent entities of the candidate news and enhance the integrity of the information contained in the candidate news embedding vector. The comparison experiments with five typical recommendation methods on two versions of the MIND news dataset show that the introduction of attention mechanism, Transformer and knowledge graph can improve the performance of the algorithm on news recommendation.

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Review of digital design and digital twin of industrial boiler
Zhe-wu CHENG,Shui-guang TONG,Zhe-ming TONG,Qin-guo ZHANG
Journal of ZheJiang University (Engineering Science)    2021, 55 (8): 1518-1528.   DOI: 10.3785/j.issn.1008-973X.2021.08.013
Abstract   HTML PDF (915KB) ( 530 )  

The characteristics of industrial boiler design and the necessity of introducing digital twin technology were summarized. The development and research status of digital design technology for industrial boilers were comprehensively summarized, and it was proposed that the digital design technology of a new generation of industrial boilers, with the design process optimization as the core and the digital twin as the foundation, was the key to improve the design capability and comprehensive performance of industrial boilers. The application characteristics of digital twin technology in industrial boiler design were analyzed, and three key technical problems of digital twin driven industrial boiler design were summarized: digital twin modeling technology for the expression of multiple information in the design process of industrial boiler; design process optimization technology based on human-computer interaction and virtual reality intelligent verification; industrial boiler digital twin data management technology for the full life cycle. On this basis, a digital twin driven digital design technology framework for industrial boilers was proposed, which was expected to provide ideas and valuable references for the research and application of digital design technology for high-performance industrial boilers.

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SQL generation from natural language queries with complex calculations on financial data
Jia-hao HE,Xi-ping LIU,Qing SHU,Chang-xuan WAN,De-xi LIU,Guo-qiong LIAO
Journal of ZheJiang University (Engineering Science)    2023, 57 (2): 277-286.   DOI: 10.3785/j.issn.1008-973X.2023.02.008
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The problem of structured query language (SQL) generation from natural language queries (Text-to-SQL) in financial domain was investigated. First, SOFT, a Text-to-SQL dataset in the financial domain was constructed. The dataset covered common queries in the financial domain with distinctive features and presented challenges to Text-to-SQL research. Then, FinSQL, a Text-to-SQL model, which optimized the support for complex queries in the financial domain, was proposed. In particular, by analyzing the characteristics of row calculation queries, a class of queries with complex numerical calculations, a divide-and-conquer based method was proposed. A row calculation query was divided into several subqueries, the SQL statement for each subquery was generated, and the SQL statements were finally combined into together to get the SQL statement for the original query. Experimental results on SOFT dataset show that the proposed FinSQL model outperforms existing methods for the hard queries, and performs well for row calculation queries.

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Video object detection algorithm based on multi-level feature aggregation under mixed sampler
Siyi QIN,Shaoyan GAI,Feipeng DA
Journal of ZheJiang University (Engineering Science)    2024, 58 (1): 10-19.   DOI: 10.3785/j.issn.1008-973X.2024.01.002
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A video object detection algorithm which was built upon the YOLOX-S single-stage detector based on mixed weighted reference-frame sampler and multi-level feature aggregation attention was proposed aiming at the problems of existing deep learning-based video object detection algorithms failing to simultaneously meet accuracy and efficiency requirements. Mixed weighted reference-frame sampler (MWRS) included weighted random sampling and local consecutive sampling to fully utilize effective global information and inter-frame local information. Multi-level feature aggregation attention (MFAA) module refined the classification features extracted by YOLOX-S based on self-attention mechanism, encouraging the network to learn richer feature information from multi-level features. The experimental results demonstrated that the proposed algorithm achieved an average precision AP50 of 77.8% on the ImageNet VID dataset with an average detection speed of 11.5 milliseconds per frame. The object classification and location performance are significantly better than that of YOLOX-S, indicating that the proposed algorithm achieves higher accuracy and faster detection speed.

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Multimodal image retrieval model based on semantic-enhanced feature fusion
Fan YANG,Bo NING,Huai-qing LI,Xin ZHOU,Guan-yu LI
Journal of ZheJiang University (Engineering Science)    2023, 57 (2): 252-258.   DOI: 10.3785/j.issn.1008-973X.2023.02.005
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A multimodal image retrieval model based on semantic-enhanced feature fusion (SEFM) was proposed to establish the correlation between text features and image features in multimodal image retrieval tasks. Semantic enhancement was conducted on the combined features during feature fusion by two proposed modules including the text semantic enhancement module and the image semantic enhancement module. Firstly, to enhance the text semantics, a multimodal dual attention mechanism was established in the text semantic enhancement module, which associated the multimodal correlation between text and image. Secondly, to enhance the image semantics, the retain intensity and update intensity were introduced in the image semantic enhancement module, which controlled the retaining and updating degrees of the query image features in combined features. Based on the above two modules, the combined features can be optimized, and be closer to the target image features. In the experiment part, the SEFM model was evaluated on MIT-States and Fashion IQ datasets, and experimental results show that the proposed model performs better than the existing works on recall and precision metrics.

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