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Journal of Systems Science & Complexity 2018年第3期31卷 608-620页

作者： duan lian School of Mathematics and Big Data Anhui University of Science and Technology

This paper studies a class of general BAM neural networks with multiple delays. Em- ploying the exponential dichotomy theory and fixed point method, together with constructing suitable Lyapunov functionals, easily verifiable delay-independent criteria are established to ensure the exis- tence and global exponential stability of pseudo almost periodic solutions, which not only generalize but also complement some existing ones. These theoretical results are also supported with numerical simulations.

关键词： General BAM neural network global exponential stability pseudo almost periodic solu-tion

Low-light image enhancement algorithm using a residual network with semantic information

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The Journal of China Universities of Posts and Telecommunications 2022年第2期29卷 52-62,84页

作者： duan lian Tang Guijin Jiangsu Key Laboratory of Image Processing and Image Communication Nanjing University of Posts and TelecommunicationsNanjing 210003China

Aiming to solve the poor performance of low illumination enhancement algorithms on uneven illumination images,a low-light image enhancement(LIME)algorithm based on a residual network was *** algorithm constructs a deep network that uses residual modules to extract image feature information and semantic modules to extract image semantic information from different ***,a composite loss function was also designed for the process of low illumination image enhancement,which dynamically evaluated the loss of an enhanced image from three factors of color,structure,and *** ensures that the model can correctly enhance the image features according to the image semantics,so that the enhancement results are more in line with the human visual *** results show that compared with the state-of-the-art algorithms,the semantic-driven residual low-light network(SRLLN)can effectively improve the quality of low illumination images,and achieve better subjective and objective evaluation indexes on different types of images.

关键词： image enhancement convolutional neural network(CNN) residual learning image semantics

A comprehensive research on wear resistance of GH4169 superalloy in longitudinal-torsional ultrasonic vibration side milling with tool wear and surface quality

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Chinese Journal of Aeronautics 2024年第4期37卷 556-573页

作者： Baoqi CHANG Zhaoxi YI Fen ZHANG lian duan Ji-an duan School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China State Key Laboratory of High Performance and Complex Manufacturing Central South UniversityChangsha 410083China School of Physics and Electronics Central South UniversityChangsha 410083China

To improve the service and machining performance of the workpiece, the tool wear mechanisms, surface machining quality, and wear resistance in conventional side milling(CSM)and longitudinal-torsional ultrasonic vibration side milling(LTUVSM) of GH4169 superalloy at different cutting lengths are investigated systematically. Tool wear mechanisms are revealed and the correlation between machined surface quality with tool wear is analyzed correspondingly. Tool wear patterns mainly include adhesive wear, diffusion wear, abrasive wear, and chipping *** surface quality is achieved in LTUVSM due to a maximum reduction of flank wear bandwidth and wear rate by 71.9% and 71.5%, respectively, compared to CSM. The friction coefficient,initial wear stage time, and wear volume of dry sliding wear were measured to evaluate the workpiece wear resistance. The maximum reductions in friction coefficient and wear volume in LTUVSM are 18.2% and 15.8% compared to CSM. The regular ultrasonic vibration textures suppress the friction and the growth of contact nodes in the contact area, decreasing the degree of surface wear, which is demonstrated by a 38.8% increase in initial wear stage time compared to *** conclusion, the workpiece in LTUVSM exhibits higher wear resistance because of the improvement of tool wear and the guarantee of surface quality.

关键词： Dry sliding wear Surface quality Tool wear Ultrasonic vibration Wear resistance

Multi-Objective Optimization for an Industrial Grinding and Classification Process Based on PBM and RSM

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IEEE/CAA Journal of Automatica Sinica 2023年第11期10卷 2124-2135页

作者： Xiaoli Wang Luming Liu lian duan Qian Liao School of Automation Central South universityChangsha 410083China Changsha Research Institute of Mining and Metallurgy Changsha 410012China

The grinding and classification process is one of the key sub-processes in mineral processing, which influences the final process indexes significantly and determines energy and ball consumption of the whole plant. Therefore, optimal control of the process has been very important in practice. In order to stabilize the grinding index and improve grinding capacity in the process,a process model based on population balance model(PBM) is calibrated in this study. The correlation between the mill power and the operating variables in the grinding process is modelled by using the response surface method(RSM), which solves the problem where the traditional power modeling method relies on some unobservable mechanism-related parameters. On this basis, a multi-objective optimization model is established to maximize the useful power of the grinding circuit to improve the throughput of the grinding operation and improve the fraction of –0.074 mm particles in the hydrocyclone overflow to smooth the subsequent flotation operation. The elite non-dominated sorting genetic algorithm-II(NSGA-II) is then employed to solve the multi-objective optimization problem. Finally, subjective and objective weighting methods and integrated multi-attribute decision-making methods are used to select the optimal solution on the Pareto optimal solution set. The results demonstrate that the throughput of the mill and the fraction of –0.074 mm particles in the overflow of the cyclone are increased by 3.83 t/h and 2.53%, respectively.

关键词： Decision-making technique grinding process multiobjective optimization response surface method(RSM)

Highly Efficient Hybrid White Tandem Organic Light-Emitting Diodes with MoO3 Layer

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Chinese Journal of Chemistry 2015年第8期33卷 859-864页

作者： lian duan Taiju Tsuboi Yong Qiu Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing 100084 China Kyoto Sangyo University Kamigamo Kita-ku Kyoto 603-8555 Japan Institute of Advanced Materials Nanjing Tech University Nanjing Jiangsu 210009 China

Electroluminescence （EL） characteristics have been studied for a hybrid tandem white organic light emitting diode （OLED） with a blue emitting fluorescent EL1 unit based on BCzVBi and a yellow emitting phosphorescent EL2 unit based on （fbi）2Ir（acac）, where a MoO3 layer is inserted between EL1 and EL2 units as charge generation layer （CGL）. Maximum current and power efficiencies of 68.1 cd/A and 29.2 lm/W were obtained, respectively, while the current and power efficiencies at luminance of 1000 cd/m2 were 68.0 cd/A and 24.6 lm/W. The yellow emission appears from about 4.5 V firstly, while the blue emission starts to appear from about 5.4 V. It was found that charge generation from CGL of MoO3/NPB bilayer occurred at high voltages of above 5.4 V but not at low voltages below 5.2 V.

关键词： organic light emitting diode white emission tandem device

A Novel Multi-Stream Fusion Network for Underwater Image Enhancement

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China Communications 2024年第2期21卷 166-182页

作者： Guijin Tang lian duan Haitao Zhao Feng Liu Jiangsu Key Laboratory of Image Processing and Image Communication Nanjing University of Posts and TelecommunicationsNanjing 210003China Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing 210003China

Due to the selective absorption of light and the existence of a large number of floating media in sea water, underwater images often suffer from color casts and detail blurs. It is therefore necessary to perform color correction and detail restoration. However,the existing enhancement algorithms cannot achieve the desired results. In order to solve the above problems, this paper proposes a multi-stream feature fusion network. First, an underwater image is preprocessed to obtain potential information from the illumination stream, color stream and structure stream by histogram equalization with contrast limitation, gamma correction and white balance, respectively. Next, these three streams and the original raw stream are sent to the residual blocks to extract the features. The features will be subsequently fused. It can enhance feature representation in underwater images. In the meantime, a composite loss function including three terms is used to ensure the quality of the enhanced image from the three aspects of color balance, structure preservation and image smoothness. Therefore, the enhanced image is more in line with human visual ***, the effectiveness of the proposed method is verified by comparison experiments with many stateof-the-art underwater image enhancement algorithms. Experimental results show that the proposed method provides superior results over them in terms of MSE,PSNR, SSIM, UIQM and UCIQE, and the enhanced images are more similar to their ground truth images.

关键词： image enhancement multi-stream fusion underwater image

Glass Recognition and Map Optimization Method for Mobile Robot Based on Boundary Guidance

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Chinese Journal of Mechanical Engineering 2023年第3期36卷 135-146页

作者： Yong Tao He Gao Yufang Wen lian duan Jiangbo Lan School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Research Institute of Aero-Engine Beihang UniversityBeijing 102206China Large Aircraft Advanced Training Center Beihang UniversityBeijing 100191China

Current research on autonomous mobile robots focuses primarily on perceptual accuracy and autonomous *** commercial and domestic constructions,concrete,wood,and glass are typically *** and visual mapping or planning algorithms are highly accurate in mapping wood panels and concrete ***,indoor and outdoor glass curtain walls may fail to perceive these transparent *** this study,a novel indoor glass recognition and map optimization method based on boundary guidance is ***,the status of glass recognition techniques is analyzed ***,a glass image segmentation network based on boundary data guidance and the optimization of a planning map based on depth repair are ***,map optimization and path-planning tests are conducted and compared using different *** results confirm the favorable adaptability of the proposed method to indoor transparent plates and glass curtain *** the proposed method,the recognition accuracy of a public test set increases to 94.1%.After adding the planning map,incorrect coverage redundancies for two test scenes reduce by 59.84%and 55.7%.Herein,a glass recognition and map optimization method is proposed that offers sufficient capacity in perceiving indoor glass materials and recognizing indoor no-entry regions.

关键词： Autonomous mobile robot Multi-sensor fusion Glass recognition Map optimization

A case-based reasoning approach for task-driven spatial-temporally aware geospatial data discovery through geoportals

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International Journal of Digital Earth 2017年第11期10卷 1146-1165页

作者： Ming Li Wei Guo lian duan Xinyan Zhu Institute of Space Science and Technology Nanchang UniversityNanchangPeople’s Republic of China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanPeople’s Republic of China Collaborative Innovation Center of Geospatial Technology WuhanPeople’s Republic of China Key Laboratory of Environment Change and Resources Use in Beibu Gulf(Guangxi Teachers Education University) Ministry of EducationGuangxiPeople’s Republic of China Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation(Guangxi Teachers Education University) GuangxiPeople’s Republic of China

There is a critical need to develop a means for fast,task-driven discovery of geospatial data found in *** geoportals,however,only provide metadata-based means for discovery,with little support for task-driven discovery,especially when considering spatial–temporal *** address this gap,this paper presents a Case-Based Reasoning-supported Geospatial Data Discovery(CBR-GDD)method and implementation that accesses geospatial data by *** advantages of the CBR-GDD approach is that it builds an analogue reasoning process that provides an internal mechanism bridging tasks and geospatial data with spatial–temporal awareness,thus providing solutions based on past *** CBR-GDD approach includes a set of algorithms that were successfully implemented via three components as an extension of geoportals:ontology-enhanced knowledge base,similarity assessment model,and case retrieval nets.A set of experiments and case studies validate the CBR-GDD approach and application,and demonstrate its efficiency.

关键词： Case-based reasoning geospatial data discovery ontology geoportals spatial–temporal awareness

Simultaneous enhancement of efficiency and stability of OLEDs with thermally activated delayed fluorescence materials by modifying carbazoles with peripheral groups

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Science China Chemistry 2019年第3期62卷 393-402页

作者： Yunge Zhang Dongdong Zhang Taiju Tsuboi Yong Qiu lian duan Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Department of Polymer Science and Engineering Zhejiang University

Albeit their high efficiencies, the operational stability of the organic light emitting diodes(OLEDs) based on thermally activated delayed fluorescence(TADF) emitters is still far from satisfaction, and few strategies have been proposed to improve their stability. Here, we show that by modifying the carbazole unit, one of the most commonly used donors in TADF emitters, with peripheral groups, both the device efficiency and operational stability can be greatly improved. Awell-known TADF molecule—4,5-di(9H-carbazol-9-yl)phthalonitrile(2CzPN) was chosen as the prototype and modified by introducing peripheral tert-butyl and phenyl groups to the 3,6-positions of the carbazole(named 2tBuCzPN and 2PhCzPN, respectively). The introduced groups not only improve the compounds' electrochemical stabilities referred to the cyclic voltammetry multi-sweep results, but also promote their photoluminescence quantum yields. Furthermore, reduced singlet-triplet energy gaps are observed, leading to the shortened exciton lifetimes which are benefit to suppress the exciton annihilations. Besides, the steric hindrance of introduced phenyl groups can partly restrain the concentration quenching of the TADF emitter. Consequently, OLEDs based on 2tBuCzPN and 2PhCzPN achieved improved maximum external quantum efficiencies(EQEs) of 17.0% and 14.0%, respectively(compared to 8.5% for 2CzPN). Meanwhile, 2PhCzPN based OLED showed reduced roll-off characteristics and a longer lifetime of 7.8 times higher than that of 2CzPN, testifying the effectiveness of subtle modification of the unstable moieties in simultaneous enhancement of efficiency and stability of OLEDs based on TADF emitters.

关键词： TADF OLED stability carbazole peripheral group

Red phosphorescent organic light-emitting diodes based on a novel host material with thermally activated delayed fluorescent properties

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Science China Chemistry 2016年第6期59卷 684-691页

作者： Yilang Li Dongdong Zhang Yunge Zhang Minghan Cai lian duan Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing 100084 China

High cost of phosphors and significant efficiency roll-off at high brightness are the two main factors that limit the wide application of phosphorescent organic light-emitting diodes （PHOLEDs）. Efforts have been paid to find ways to reduce the phosphors＇ concentration and efficiency roll-off of PHOLEDs. In this work, we reported red emission PHOLEDs with low dopant concentration and low efficiency roll-off based on a novel host material 2,4-biscyanophenyl-6-（12-phenylindole[2,3-a]carbazole-ll-yl）-1,3,5-triazine （BCPICT）, with thermally activated delayed fluorescent （TADF） properties. The device with 1.0% dopant concentration displayed a maximum external quantum efficiency of 10.7%. When the dopant concentration was increased to 2.0%, the device displayed a maximum external quantum efficiency of 10.5% and a low efficiency roll-off of 5.7% at 1000 cd/m^2.

关键词： phosphorescent organic light-emitting diodes red emission efficiency roll-off thermally activated delayed fluorescence