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A Hybrid Feature Fusion Traffic Sign Detection Algorithm Based on YOLOv7

Computers, Materials & Continua 2024年第7期80卷 1425-1440页

作者： Bingyi ren Juwei Zhang Tong Wang School of Mechanical Engineering Henan University of Science and TechnologyLuoyang471000China School of Information Engineering Henan University of Science and TechnologyLuoyang471000China School of Electronic Information Zhengzhou Institute of Aeronautical Industry ManagementZhengzhou450046China Henan Province New Energy Vehicle Power Electronics and Power Transmission Engineering Research Center Luoyang471000China

Autonomous driving technology has entered a period of rapid development,and traffic sign detection is one of the important *** target detection networks are difficult to adapt to scenarios where target sizes are seriously imbalanced,and traffic sign targets are small and have unclear features,which makes detection more ***,we propose aHybrid Feature Fusion Traffic Sign detection algorithmbased onYOLOv7(HFFTYOLO).First,a self-attention mechanism is incorporated at the end of the backbone network to calculate feature interactions within scales;Secondly,the cross-scale fusion part of the neck introduces a bottom-up multi-path fusion *** reuse paths at the end of the neck,paying particular attention to cross-scale fusion of highlevel *** addition,we found the appropriate channel width through a lot of experiments and reduced the superfluous *** terms of training,a newregression lossCMPDIoUis proposed,which not only considers the problem of loss degradation when the aspect ratio is the same but the width and height are different,but also enables the penalty term to dynamically change at different ***,our proposed improved method shows excellent results on the TT100K *** with the baseline model,without increasing the number of parameters and computational complexity,AP0.5 and AP increased by 2.2%and 2.7%,respectively,reaching 92.9%and 58.1%.

关键词： Small target detection YOLOv7 traffic sign detection regression loss

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Energy and exergy analyses and optimizations for two-stage TEC driven by two-stage TEG with Thomson effect

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Science China(Technological Sciences) 2024年第4期67卷 1077-1093页

作者： CHEN LinGen GE YanLin FENG HuiJun ren TingTing Institute of Thermal Science and Power Engineering Wuhan Institute of TechnologyWuhan 430205China Hubei Provincial Engineering Technology Research Center of Green Chemical Equipment Wuhan 430205China School of Mechanical&Electrical Engineering Wuhan Institute of TechnologyWuhan 430205China

Based on the non-equilibrium thermodynamics and energy and exergy analyses,a thermodynamic model of two-stage thermoelectric(TE)cooler(TTEC)driven by two-stage TE generator(TTEG)(TTEG-TTEC)combined TE device is established with involving Thomson effect by fitting method of variable physical parameters of TE *** total number of TE elements as constraint,influences of number distributions of TE elements on three device performance indictors,that is,cooling load,maximum COP and maximum exergetic efficiency,are *** number distributions of TE elements are optimized with three maximum performance indictors as the objectives,*** of hot-junction temperature of TTEG and coldjunction temperature of TTEC on optimization results are analyzed,and difference between optimization results corresponding to three performance indicators are *** performance intervals and optimal variable intervals are *** of Thomson effect on three general performance indicators,three optimal performance indicators and optimal variables are comparatively *** effect reduces three general performance indicators and three optimal performance indicators of *** hot-and cold-junction temperatures of TTEG and TTEC are 450,305,325 and 295 K,respectively,Thomson effect reduced maximum cooling load,maximum COP and maximum exergetic efficiency from 9.528 W,9.043×10^(-2)and2.552%to 6.651 W,6.286×10^(-2)and 1.752%,respectively.

关键词： non-equilibrium thermodynamics cooling load COP exergetic efficiency combined thermoelectric device performance optimization

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A model reduction approach for discrete-time linear time-variant systems with delayed inputs

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Science China(Information Sciences) 2024年第4期67卷 197-217页

作者： Ai-Guo WU Guang-ren DUAN Yu WANG Jie ZHANG School of Mechanical Engineering and Automation Harbin Institute of Technology(Shenzhen) HIT Wuhu Robot Technology Research Institute Center for Control Science and Technology Southern University of Science and Technology

A model reduction approach is presented for discrete-time linear time-variant input-delayed systems. According to this proposed approach, a dynamical variable is constructed by taking advantage of the current state and historical information of input. It is revealed that the behavior of this dynamical variable is governed by a discrete-time linear delay-free system. It is worth noting that the presented variable transformation does not require the system matrix to be invertible. Based on the reduced delay-free models,stabilizing control laws can be easily obtained for the original delayed system. For the case with a single input delay, the constructed variable is an exact prediction for the future state, and thus the stabilizing control law could be designed by replacing the future state with its prediction. Finally, three discrete-time periodic systems with delayed input are employed to illustrate how to utilize the presented model reduction approaches.

关键词： reduction approach predictor-based feedback time-varying systems delayed input periodic system

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Afforestation increases microbial diversity in low-carbon soils

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Journal of Forestry Research 2024年第2期35卷 14-22页

作者： Xuesen Pang Chuankuan Wang Chengjie ren Zhenghu Zhou Center for Ecological Research Key Laboratory of Sustainable Forest Ecosystem Management‑Ministry of EducationNortheast Forestry UniversityHarbin 150040People’s Republic of China Northeast Asia Biodiversity Research Center Northeast Forestry UniversityHarbin 150040People’s Republic of China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F UniversityYangling 712100People’s Republic of China

Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of plantings on soil microbial *** results showed that the overall effect of afforestation on soil microbial diversity was positive across the *** forest algorithm suggested that soil carbon was the most important factor regulating microbial diversity and the positive response was only found with new plantings on low-carbon bare lands but not on high-carbon farmlands and *** addition,afforestation with broadleaved species increased microbial diversity,whereas planting with conifers had no effect on microbial *** study clarified the effects of plantings on soil microbial diversity,which has an important implication for establishing appropriate policies and practices to improve the multiple functionalities(e.g.,biodiversity conservation and climate change mitigation)during plantation establishment.

关键词： Afforestation Microbial diversity Soil microbial communities Species-energy theory Plantations

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Primitive functional groups directed distinct photocatalytic performance of imine-linked donor-acceptor covalent organic frameworks

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Nano Research 2024年第6期17卷 4994-5001页

作者： Xitong ren Jiajie Sun Yusen Li Feng Bai Key Laboratory for Special Functional Materials of Ministry of Education National and Local Joint Engineering Research Center for High-Efficiency Display and Lighting TechnologySchool of Materials Science and Engineeringand Collaborative Innovation Center of Nano Functional Materials and ApplicationsHenan UniversityKaifeng 475004China School of Physics and Electronics Henan UniversityKaifeng 475004China

The combination of donor-acceptor(D-A)structures presents a viable strategy for fabricating covalent organic frameworks(COFs)with exceptional photocatalytic ***,the selection of functional groups on donor or acceptor building blocks and their effect on the macroscopic properties of COFs are *** this study,we tactfully synthesized a pair of Py-DBT-COFs from the same pyrene(Py)donor and 4,7-diphenylbenzo[c][1,2,5]thiadiazole(DBT)acceptor cores with distinct primitive functional *** primitive functional groups of building units determine the photocatalytic properties of corresponding ***,Py-C-DBT-COF synthesized from Py-4CHO and DBT-2NH_(2)showcases a splendid H_(2)evolution rate as high as 21,377.7μmol/(g·h)(with 5 wt.%Pt)originating from better charge transfer capacity,which is significantly superior to that of Py-N-DBT-COF constructed from Py-4NH_(2)and *** distinct photocatalytic performances of the two COFs are demonstrated to originate from the different charge separation and transfer *** work supplies a new avenue for optimizing the photocatalytic performance of D-A COFs from the perspective of primitive functional group selections.

关键词： covalent organic frameworks functional group donor-acceptor photocatalysis

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Reduced macular thickness and vascular density in abnormal glucose metabolism patients:A meta-analysis of optical coherence tomography(OCT)and OCT angiography studies

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Chinese Medical Journal 2024年第9期137卷 1054-1068页

作者： Xiangyu Fu Xiang ren Wenyue Chen Danian Chen Department of Ophthalmology West China HospitalSichuan UniversityChengduSichuan 610041China Research Laboratory of Ophthalmology and Vision Sciences State Key Laboratory of BiotherapyWest China HospitalSichuan UniversityChengduSichuan 610041China Department of Ophthalmology The People’s Hospital of Guizhou ProvinceGuiyangGuizhou 550002China

Background:Alterations in macular thickness and vascular density before clinically visible diabetic retinopathy(DR)remain *** study aimed to determine whether retinal manifestations in abnormal glucose metabolism(AGM)patients differ from those in the healthy ***:PubMed,Embase,and Web of Science were searched between 2000 and *** eligibility criteria were AGM patients without *** and secondary outcomes measured by optical coherence tomography(OCT)and OCT angiography(OCTA)were analyzed and expressed as standardized mean differences(SMDs)with 95%confidence intervals(CIs).A random-effects model was used in the data *** potential publication bias for the variables was evaluated using Egger’s ***:A total of 86 observational studies involving 13,773 participants and 15,416 eyes were *** revealed that compared to healthy controls,the total macular thickness of AGM patients was thinner,including the thickness of fovea(-0.24,95%CI[-0.39,-0.08];P=0.002,I^(2)=87.7%),all regions of parafovea(-0.32,95%CI[-0.54,-0.11];P=0.003;I^(2)=71.7%)and the four quadrants of perifovea;the thickness of peripapillary retinal nerve fiber layer(pRNFL),macular retinal nerve fiber layer(mRNFL),and ganglion cell layer(GCL)also *** indicated that the superficial and deep vascular density decreased,the foveal avascular zone(FAZ)area enlarged,and the acircularity index(AI)reduced in AGM ***:Retinal thinning and microvascular lesions have occurred before the advent of clinically detectable DR;OCT and OCTA may have the potential to detect these preclinical ***:PROSPERO;http://***/prospero/;***42021269885.

关键词： Abnormal glucose metabolism Optical coherence tomography Optical coherence tomography angiography Diabetic retinopathy Prediabetes Meta-analysis

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In-situ UV-Vis Spectroscopy of Trisulfur Radicals in Lithium-Sulfur Batteries

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Chemical Research in Chinese Universities 2024年第2期40卷 279-286页

作者： DOU renju WANG Qin ren Xiaoyan LU Lehui School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026P.R.China State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022P.R.China

Here we employ in-situ UV-Vis spectroscopy to monitor the sulfur redox reaction with oxygen-containing molecules as an additive,for example,biphenyl-4,4′-dicarboxylic acid(BDC).Furthermore,Raman spectrum,electron paramagnetic resonance(EPR),and electrospray ionization-mass spectrometry(ESI-MS)measurements reveal that the formation of BDC-S_(3)•^(‒)complexes can establish the long-term stability of polysulfide radicals,change the kinetics of sulfur redox reaction,and then generate decent capacity retention and rate *** to the density functional theory(DFT)analysis,S_(3)•^(‒)radicals are the underlying product of S_(6)^(2‒)cleavage,owing to the decreased chemical energy and the increased stability of S_(3)•^(‒)radicals through Lewis acid-base *** assembled Li-S batteries with BDC additive deliver a high reversible capacity of 420 mA·h·g^(−1)over 200 cycles with over 98%Coulombic efficiency,under the current density of 0.2 C.

关键词： Radical Polysulfide In-situ UV-Vis Spectroscopy Electrolyte additive Lithium-sulfur battery

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An Interactive Collaborative Creation System for Shadow Puppets Based on Smooth Generative Adversarial Networks

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Computers, Materials & Continua 2024年第6期79卷 4107-4126页

作者： Cheng Yang Miaojia Lou Xiaoyu Chen Zixuan ren Department of Industrial Design Hangzhou City UniversityHangzhou310000China College of Computer Science and Technology Zhejiang UniversityHangzhou310000China

Chinese shadow puppetry has been recognized as a world intangible cultural ***,it faces substantial challenges in its preservation and advancement due to the intricate and labor-intensive nature of crafting shadow *** ensure the inheritance and development of this cultural heritage,it is imperative to enable traditional art to flourish in the digital *** paper presents an Interactive Collaborative Creation System for shadow puppets,designed to facilitate the creation of high-quality shadow puppet images with greater *** system comprises four key functions:Image contour extraction,intelligent reference recommendation,generation network,and color adjustment,all aimed at assisting users in various aspects of the creative process,including drawing,inspiration,and content ***,we propose an enhanced algorithm called Smooth Generative Adversarial Networks(SmoothGAN),which exhibits more stable gradient training and a greater capacity for generating high-resolution shadow puppet ***,we have built a new dataset comprising high-quality shadow puppet images to train the shadow puppet generation *** qualitative and quantitative experimental results demonstrate that SmoothGAN significantly improves the quality of image generation,while our system efficiently assists users in creating high-quality shadow puppet images,with a SUS scale score of *** study provides a valuable theoretical and practical reference for the digital creation of shadow puppet art.

关键词： Shadow puppets deep learning image generation co-create

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Understanding Discrepancy of Power System Dynamic Security Assessment with Unknown Faults: A Reliable Transfer Learning-based Method

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 427-431页

作者： Chao ren Han Yu Yan Xu Zhao Yang Dong School of Computer Science and Engineering Nanyang Technological UniversitySingapore School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore

This letter proposes a reliable transfer learning(RTL)method for pre-fault dynamic security assessment(DSA)in power systems to improve DSA performance in the presence of potentially related unknown *** takes individual discrepancies into consideration and can handle unknown faults with incomplete *** experiment results demonstrate high DSA accuracy and computational efficiency of the proposed RTL *** analysis shows RTL can guarantee system performance.

关键词： Adversarial training dynamic security assessment maximum classifier discrepancy missing data transfer learning

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Prescribed time control based on the periodic delayed sliding mode surface without singularities

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Science China(Information Sciences) 2024年第7期67卷 256-270页

作者： Bin ZHOU Yi DING Kang-Kang ZHANG Guang-ren DUAN Center for Control Theory and Guidance Technology Harbin Institute of Technology

In this paper, nonsingular prescribed-time control is studied based on periodic delayed sliding mode surfaces. Different from the existing sliding mode control, where either singularity problems may appear or the convergence time depends on the initial state, the proposed sliding mode control approaches can achieve prescribed-time convergence without singularity. The proposed nonsingular sliding mode control approaches can be applied to both second-order and high-order nonlinear systems with prescribed-time convergence. As applications of the proposed sliding mode control approaches, the control of hypersonic vehicle systems is revisited. Numerical simulations on the nonlinear model of the hypersonic vehicle system show the effectiveness of the proposed methods.

关键词： prescribed-time control smooth periodic delayed feedback sliding mode control high-order nonlinear systems hypersonic vehicle systems

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