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Development and application of a multi-physics and multi-scale coupling program for lead-cooled fast reactor 被引量:9
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作者 Xiao Luo Chi Wang +4 位作者 Ze-Ren Zou Lian-Kai Cao Shuai Wang Zhao Chen Hong-Li Chen 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第2期40-52,共13页
In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and t... In this study,a multi-physics and multi-scale coupling program,Fluent/KMC-sub/NDK,was developed based on the user-defined functions(UDF)of Fluent,in which the KMC-sub-code is a sub-channel thermal-hydraulic code and the NDK code is a neutron diffusion code.The coupling program framework adopts the"master-slave"mode,in which Fluent is the master program while NDK and KMC-sub are coupled internally and compiled into the dynamic link library(DLL)as slave codes.The domain decomposition method was adopted,in which the reactor core was simulated by NDK and KMC-sub,while the rest of the primary loop was simulated using Fluent.A simulation of the reactor shutdown process of M2LFR-1000 was carried out using the coupling program,and the code-to-code verification was performed with ATHLET,demonstrating a good agreement,with absolute deviation was smaller than 0.2%.The results show an obvious thermal stratification phenomenon during the shutdown process,which occurs 10 s after shutdown,and the change in thermal stratification phenomena is also captured by the coupling program.At the same time,the change in the neutron flux density distribution of the reactor was also obtained. 展开更多
关键词 Multi-physics and multi-scale coupling method User-defined functions Dynamic link library Thermal stratification Lead-cooled fast reactor
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Multi-scale coupling simulation in directional solidification of superalloy based on cellular automaton-finite difference method 被引量:1
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作者 Zhao Guo Jian-xin Zhou +3 位作者 Ya-jun Yin Dong-qiao Zhang Xiao-yuan Ji Xu Shen 《China Foundry》 SCIE 2017年第5期398-404,共7页
Casting microstructure evolution is difficult to describe quantitatively by only a separate simulation of dendrite scale or grain scale, and the numerical simulation of these two scales is difficult to render compatib... Casting microstructure evolution is difficult to describe quantitatively by only a separate simulation of dendrite scale or grain scale, and the numerical simulation of these two scales is difficult to render compatible. A three-dimensional cellular automaton model couplling both dendritic scale and grain scale is developed to simulate the microstructure evolution of the nickel-based single crystal superalloy DD406. Besides, a macro–mesoscopic/microscopic coupling solution algorithm is proposed to improve computational efficiency. The simulation results of dendrite growth and grain growth of the alloy are obtained and compared with the results given in previous reports. The results show that the primary dendritic arm spacing and secondary dendritic arm spacing of the dendritic growth are consistent with the theoretical and experimental results. The mesoscopic grain simulation can be used to obtain results similar to those of microscopic dendrites simulation. It is indicated that the developed model is feasible and effective. 展开更多
关键词 multi-scale coupling dendritic growth grain growth directional solidification cellular automata numerical simulation
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Multi-scale coupling analysis of urbanization and ecosystem services supply-demand budget in the Beijing-Tianjin-Hebei region, China 被引量:11
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作者 ZHANG Fan XU Ning +2 位作者 WANG Chao GUO Mingjing Pankaj KUMAR 《Journal of Geographical Sciences》 SCIE CSCD 2023年第2期340-356,共17页
Rapid economic development and human activities have severely affected ecosystem function.Analysis of the spatial distribution of areas of rapid urbanization is the basis for optimizing urban-ecological spatial design... Rapid economic development and human activities have severely affected ecosystem function.Analysis of the spatial distribution of areas of rapid urbanization is the basis for optimizing urban-ecological spatial design.This paper evaluated the spatial distribution of urbanization in the Beijing-Tianjin-Hebei(BTH)region,and then quantified the ecosystem services(ES)budget in the region based on an ES supply and demand matrix.The results showed that(1)urbanization patterns in the BTH region were relatively stable from 2000 to 2015,with clear patterns of low levels of urbanization in the northwest and high levels in the southeast;(2)areas with positive ES budget values were found throughout the region,except in built-up areas,with high ES supply areas concentrated in the northwest,and high ES demand areas in the southeast;(3)at both the county and prefecture-city levels,urbanization had negative,positive,and negative correlations with ES supply,demand,and budget,respectively;(4)the coupling coordination degree(CCD)increased,with high CCD values in the southeast.Based on these results,policy recommendations include strengthening rational land-use planning and ecosystem management,promoting the coordinated development of the economy and ecological function,and coordinating the provision of production-life-ecological functions. 展开更多
关键词 URBANIZATION ecosystem services supply-demand coupling Beijing-Tianjin-Hebei region
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Coupling mechanism analysis of CO_(2) non-Darcy flow in multi-scale reservoirs: A case study of the life-cycle process of fracturing-development in shale oil reservoirs
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作者 Zhen-Hua Rui Hai-Yang Deng +4 位作者 Ting Hu Guang-Long Sheng Malcolm Wilson Birol Dindoruk Shirish Patil 《Petroleum Science》 2025年第3期1171-1199,共29页
With policy support for carbon capture,utilization,and storage(CCUS),an integrated approach that combines energy storage fracturing,CO_(2)-enhanced oil recovery(EOR),and storage emerges as a promising direction for th... With policy support for carbon capture,utilization,and storage(CCUS),an integrated approach that combines energy storage fracturing,CO_(2)-enhanced oil recovery(EOR),and storage emerges as a promising direction for the shale oil industry.The process of energy storage fracturing induces significant changes in the pressure and saturation of the medium.However,conventional simulations often overlook the effects of fracturing and shut-in operations on the seepage field and production performance.Furthermore,fractured shale reservoirs exhibit complex non-Darcy flow characteristics due to intricate pore structures and multi-scale porous media.A comprehensive understanding of flow mechanisms is essential for effective reservoir development and CO_(2) storage.This study establishes a multi-component simulation model that encompasses the life-cycle of fracturing,shut-in,production,and CO_(2) huff-n-puff processes,thereby ensuring the continuity of the seepage field.The model accounts for the effect of nano-confinement on phase behavior by modifying the equation of state.Furthermore,the flux term is adjusted to incorporate Maxwell–Stefan diffusion,pre-/post-Darcy flow,and stress sensitivity.The embedded discrete fracture model(EDFM)is employed to simulate multiphase flow within multi-scale media,and the results from the validation model align satisfactorily with those derived from ECLIPSE.Mechanism analysis indicates that the interaction of multiple mechanisms significantly influences both production and storage performance.Under the multi-mechanism coupling,the cumulative oil production increased by 12.01%,while the utilization and storage factors increased by 62.93%and 8.93%,respectively.The role of molecular diffusion in shale oil reservoirs may be overstated,contributing only a 0.26% enhancement in oil production.Simulation results show that the energy storage fracturing strategy can increase oil production and net present value by 12.47%and 15.07%,respectively.Sensitivity analysis indicates that the CO_(2) injection rate is the main factor affecting the recovery factor,followed by CO_(2) injection time and the number of cycles,with fracturing fluid volume having the least impact.This study develops a multi-process,multi-mechanism simulation framework for multi-scale shale oil reservoirs.This framework provides a robust evaluation system for CCUS-EOR,facilitating informed decision-making in fracturing stimulation,development planning,and parameter optimization. 展开更多
关键词 Shale oil reservoir Life-cycle simulation Multiple mechanism coupling Non-Darcy flow CCUS-EOR
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Coupling of methanol and long chain alkanes on molecular sieves with CHA structures
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作者 YANG Chuang WANG Kangjun +1 位作者 LI Jinzhe LIU Zhongmin 《燃料化学学报(中英文)》 北大核心 2026年第2期64-75,共12页
The coupling reactions of methanol and long-chain alkanes(n-dodecane,n-tetradecane and n-hexadecane)over CHA-type molecular sieves were studied in a fixed bed reactor.Over SAPO-34 and SSZ-13,it was found that the indu... The coupling reactions of methanol and long-chain alkanes(n-dodecane,n-tetradecane and n-hexadecane)over CHA-type molecular sieves were studied in a fixed bed reactor.Over SAPO-34 and SSZ-13,it was found that the induction period of methanol conversion was shortened by the introduction of long-chain alkanes.However,the addition of long-chain alkanes had little influence on the product distribution.Polymethylbenzenes and the derivatives were the main retained species on spent SSZ-13 catalyst,while adamantanes were the main retained species on SAPO-34.This indicates that coking species formation was mainly related to the further transformation of long-chain alkane/methanol coupling products at acid sites of the molecular sieve.These findings provide valuable information of long chain alkanes conversion and methanol reaction behavior of induction period over small pore CHA molecular sieves. 展开更多
关键词 METHANOL long-chain alkane coupling transformation induction period molecular sieves
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Numerical Simulation on Thermomechanical Coupling Process in Friction Stir-Assisted Wire Arc Additive Manufacturing
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作者 Li Long Xiao Yichen +2 位作者 Shi Lei Chen Ji Wu Chuansong 《稀有金属材料与工程》 北大核心 2026年第1期1-8,共8页
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit... Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties. 展开更多
关键词 friction stir processing wire arc additive manufacturing numerical simulation thermomechanical coupling temperature field DEFORMATION
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Cul-Catalyzed C—C Bond Coupling Reaction for the Construction of 2-Carbonyl-1,4-diketones
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作者 Liu Yingjie Min Laisheng +3 位作者 Yang Ruirong Song Dongxue Peng Rui Liang Deqiang 《有机化学》 北大核心 2026年第2期603-611,共9页
Transition metal-catalyzed C—C coupling reactions are a core strategy for the construction of carbon-carbon bonds in organic synthesis.Their development has not only promoted the synthesis of drugs,materials,and natu... Transition metal-catalyzed C—C coupling reactions are a core strategy for the construction of carbon-carbon bonds in organic synthesis.Their development has not only promoted the synthesis of drugs,materials,and natural products,but also promoted the development of new synthetic methods,and has also made breakthroughs in mechanism innovation and catalyst design.On this basis,a copper-catalyzed radical reaction between ketones is reported,enabling the synthesis of 2-carbonyl-1,4-diones.The method exhibits excellent applicability to multiple structural types of ketones,including aliphatic ketones with diverse substituents,aromatic ketones,and various simple ketones not limited to acetone,with wide applications,easy implementation,low catalyst toxicity,and low cost,cost-effective,and the product is easy to separate and purify. 展开更多
关键词 transition metal catalysis C—C coupling radical reaction 2-carbonyl-1 4-dione
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M2ATNet: Multi-Scale Multi-Attention Denoising and Feature Fusion Transformer for Low-Light Image Enhancement
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作者 Zhongliang Wei Jianlong An Chang Su 《Computers, Materials & Continua》 2026年第1期1819-1838,共20页
Images taken in dim environments frequently exhibit issues like insufficient brightness,noise,color shifts,and loss of detail.These problems pose significant challenges to dark image enhancement tasks.Current approach... Images taken in dim environments frequently exhibit issues like insufficient brightness,noise,color shifts,and loss of detail.These problems pose significant challenges to dark image enhancement tasks.Current approaches,while effective in global illumination modeling,often struggle to simultaneously suppress noise and preserve structural details,especially under heterogeneous lighting.Furthermore,misalignment between luminance and color channels introduces additional challenges to accurate enhancement.In response to the aforementioned difficulties,we introduce a single-stage framework,M2ATNet,using the multi-scale multi-attention and Transformer architecture.First,to address the problems of texture blurring and residual noise,we design a multi-scale multi-attention denoising module(MMAD),which is applied separately to the luminance and color channels to enhance the structural and texture modeling capabilities.Secondly,to solve the non-alignment problem of the luminance and color channels,we introduce the multi-channel feature fusion Transformer(CFFT)module,which effectively recovers the dark details and corrects the color shifts through cross-channel alignment and deep feature interaction.To guide the model to learn more stably and efficiently,we also fuse multiple types of loss functions to form a hybrid loss term.We extensively evaluate the proposed method on various standard datasets,including LOL-v1,LOL-v2,DICM,LIME,and NPE.Evaluation in terms of numerical metrics and visual quality demonstrate that M2ATNet consistently outperforms existing advanced approaches.Ablation studies further confirm the critical roles played by the MMAD and CFFT modules to detail preservation and visual fidelity under challenging illumination-deficient environments. 展开更多
关键词 Low-light image enhancement multi-scale multi-attention TRANSFORMER
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Coupling Development Between Digital Economy–Agriculture Integration and Rural Revitalization in China:Spatiotemporal Disparities and Evolution Trends
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作者 Peng Xiangjun Jia Qingsong 《Contemporary Social Sciences》 2026年第1期71-89,共19页
This study aims to promote the optimization and upgrading of the economic structure in rural areas of China by focusing on the coupling coordination mechanism between digital economy–agriculture integration and rural... This study aims to promote the optimization and upgrading of the economic structure in rural areas of China by focusing on the coupling coordination mechanism between digital economy–agriculture integration and rural revitalization.By examining panel data from 30 Chinese provinces,autonomous regions,and municipalities between 2011 and 2022,the research constructs a weight-based evaluation system that integrates subjective and objective methods and a coupling coordination model to reveal its dynamic evolution patterns.Key findings indicate that digital economy–agriculture integration and rural revitalization achieve cross-coupling through critical activities.The impact of digital-agriculture integration on advancing rural revitalization lags by 2–3 years.Although the coupling development degree between the two systems continues to improve,it remains at the stage of primary coordination.Regional disparities are significant,showing a gradient pattern of“high degree of coupling development in the east and low degree of coupling development in the west.” 展开更多
关键词 digital economy-agriculture integration rural revitalization coupling coordination coupling development
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Intralayer structure reconstruction of general weighted output-coupling multilayer complex networks
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作者 Xinwei Wang Yayong Wu +1 位作者 Ying Zheng Guo-Ping Jiang 《Chinese Physics B》 2026年第2期287-299,共13页
Multilayer complex dynamical networks,characterized by the intricate topological connections and diverse hierarchical structures,present significant challenges in determining complete structural configurations due to ... Multilayer complex dynamical networks,characterized by the intricate topological connections and diverse hierarchical structures,present significant challenges in determining complete structural configurations due to the unique functional attributes and interaction patterns inherent to different layers.This paper addresses the critical question of whether structural information from a known layer can be used to reconstruct the unknown intralayer structure of a target layer within general weighted output-coupling multilayer networks.Building upon the generalized synchronization principle,we propose an innovative reconstruction method that incorporates two essential components in the design of structure observers,the cross-layer coupling modulator and the structural divergence term.A key advantage of the proposed reconstruction method lies in its flexibility to freely designate both the unknown target layer and the known reference layer from the general weighted output-coupling multilayer network.The reduced dependency on full-state observability enables more deployment in engineering applications with partial measurements.Numerical simulations are conducted to validate the effectiveness of the proposed structure reconstruction method. 展开更多
关键词 multilayer network structure reconstruction cross-layer coupling modulator output coupling
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Efficient Video Emotion Recognition via Multi-Scale Region-Aware Convolution and Temporal Interaction Sampling
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作者 Xiaorui Zhang Chunlin Yuan +1 位作者 Wei Sun Ting Wang 《Computers, Materials & Continua》 2026年第2期2036-2054,共19页
Video emotion recognition is widely used due to its alignment with the temporal characteristics of human emotional expression,but existingmodels have significant shortcomings.On the one hand,Transformermultihead self-... Video emotion recognition is widely used due to its alignment with the temporal characteristics of human emotional expression,but existingmodels have significant shortcomings.On the one hand,Transformermultihead self-attention modeling of global temporal dependency has problems of high computational overhead and feature similarity.On the other hand,fixed-size convolution kernels are often used,which have weak perception ability for emotional regions of different scales.Therefore,this paper proposes a video emotion recognition model that combines multi-scale region-aware convolution with temporal interactive sampling.In terms of space,multi-branch large-kernel stripe convolution is used to perceive emotional region features at different scales,and attention weights are generated for each scale feature.In terms of time,multi-layer odd-even down-sampling is performed on the time series,and oddeven sub-sequence interaction is performed to solve the problem of feature similarity,while reducing computational costs due to the linear relationship between sampling and convolution overhead.This paper was tested on CMU-MOSI,CMU-MOSEI,and Hume Reaction.The Acc-2 reached 83.4%,85.2%,and 81.2%,respectively.The experimental results show that the model can significantly improve the accuracy of emotion recognition. 展开更多
关键词 multi-scale region-aware convolution temporal interaction sampling video emotion recognition
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Synchronization Stability Analysis of Multi-VSC Grid-connected System via Multi-scale Method
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作者 Meng Huang Yangjian Ling +3 位作者 Han Yan Xikun Fu Xiaoming Zha Herbert Ho-Ching Iu 《CSEE Journal of Power and Energy Systems》 2026年第1期282-293,共12页
In a multiple voltage source converter(VSC)system,the nonlinear characteristics of phase-locked loops(PLLs)and their interactions have a significant influence on the synchronization stability of converters.In this pap... In a multiple voltage source converter(VSC)system,the nonlinear characteristics of phase-locked loops(PLLs)and their interactions have a significant influence on the synchronization stability of converters.In this paper,these influences are investigated from the perspective of the time domain.First,a novel time-domain model of the multi-VSC system is obtained by using a multi-scale method.On this basis,a stability criterion is proposed to assess the synchronization stability of the system.Then,the accuracy of the time-domain model and its stability criterion in various conditions are discussed.Moreover,the negative impact of the interaction on the system is quantified.Finally,the above theoretical analysis is also verified in the controller hardware-in-the-loop(CHIL)experiments. 展开更多
关键词 multi-scale method multi-VSC phase-locked loops synchronization stability time-domain model
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Research on Camouflage Target Detection Method Based on Edge Guidance and Multi-Scale Feature Fusion
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作者 Tianze Yu Jianxun Zhang Hongji Chen 《Computers, Materials & Continua》 2026年第4期1676-1697,共22页
Camouflaged Object Detection(COD)aims to identify objects that share highly similar patterns—such as texture,intensity,and color—with their surrounding environment.Due to their intrinsic resemblance to the backgroun... Camouflaged Object Detection(COD)aims to identify objects that share highly similar patterns—such as texture,intensity,and color—with their surrounding environment.Due to their intrinsic resemblance to the background,camouflaged objects often exhibit vague boundaries and varying scales,making it challenging to accurately locate targets and delineate their indistinct edges.To address this,we propose a novel camouflaged object detection network called Edge-Guided and Multi-scale Fusion Network(EGMFNet),which leverages edge-guided multi-scale integration for enhanced performance.The model incorporates two innovative components:a Multi-scale Fusion Module(MSFM)and an Edge-Guided Attention Module(EGA).These designs exploit multi-scale features to uncover subtle cues between candidate objects and the background while emphasizing camouflaged object boundaries.Moreover,recognizing the rich contextual information in fused features,we introduce a Dual-Branch Global Context Module(DGCM)to refine features using extensive global context,thereby generatingmore informative representations.Experimental results on four benchmark datasets demonstrate that EGMFNet outperforms state-of-the-art methods across five evaluation metrics.Specifically,on COD10K,our EGMFNet-P improves F_(β)by 4.8 points and reduces mean absolute error(MAE)by 0.006 compared with ZoomNeXt;on NC4K,it achieves a 3.6-point increase in F_(β).OnCAMO and CHAMELEON,it obtains 4.5-point increases in F_(β),respectively.These consistent gains substantiate the superiority and robustness of EGMFNet. 展开更多
关键词 Camouflaged object detection multi-scale feature fusion edge-guided image segmentation
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MewCDNet: A Wavelet-Based Multi-Scale Interaction Network for Efficient Remote Sensing Building Change Detection
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作者 Jia Liu Hao Chen +5 位作者 Hang Gu Yushan Pan Haoran Chen Erlin Tian Min Huang Zuhe Li 《Computers, Materials & Continua》 2026年第1期687-710,共24页
Accurate and efficient detection of building changes in remote sensing imagery is crucial for urban planning,disaster emergency response,and resource management.However,existing methods face challenges such as spectra... Accurate and efficient detection of building changes in remote sensing imagery is crucial for urban planning,disaster emergency response,and resource management.However,existing methods face challenges such as spectral similarity between buildings and backgrounds,sensor variations,and insufficient computational efficiency.To address these challenges,this paper proposes a novel Multi-scale Efficient Wavelet-based Change Detection Network(MewCDNet),which integrates the advantages of Convolutional Neural Networks and Transformers,balances computational costs,and achieves high-performance building change detection.The network employs EfficientNet-B4 as the backbone for hierarchical feature extraction,integrates multi-level feature maps through a multi-scale fusion strategy,and incorporates two key modules:Cross-temporal Difference Detection(CTDD)and Cross-scale Wavelet Refinement(CSWR).CTDD adopts a dual-branch architecture that combines pixel-wise differencing with semanticaware Euclidean distance weighting to enhance the distinction between true changes and background noise.CSWR integrates Haar-based Discrete Wavelet Transform with multi-head cross-attention mechanisms,enabling cross-scale feature fusion while significantly improving edge localization and suppressing spurious changes.Extensive experiments on four benchmark datasets demonstrate MewCDNet’s superiority over comparison methods:achieving F1 scores of 91.54%on LEVIR,93.70%on WHUCD,and 64.96%on S2Looking for building change detection.Furthermore,MewCDNet exhibits optimal performance on the multi-class⋅SYSU dataset(F1:82.71%),highlighting its exceptional generalization capability. 展开更多
关键词 Remote sensing change detection deep learning wavelet transform multi-scale
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YOLO-SPDNet:Multi-Scale Sequence and Attention-Based Tomato Leaf Disease Detection Model
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作者 Meng Wang Jinghan Cai +6 位作者 Wenzheng Liu Xue Yang Jingjing Zhang Qiangmin Zhou Fanzhen Wang Hang Zhang Tonghai Liu 《Phyton-International Journal of Experimental Botany》 2026年第1期290-308,共19页
Tomato is a major economic crop worldwide,and diseases on tomato leaves can significantly reduce both yield and quality.Traditional manual inspection is inefficient and highly subjective,making it difficult to meet th... Tomato is a major economic crop worldwide,and diseases on tomato leaves can significantly reduce both yield and quality.Traditional manual inspection is inefficient and highly subjective,making it difficult to meet the requirements of early disease identification in complex natural environments.To address this issue,this study proposes an improved YOLO11-based model,YOLO-SPDNet(Scale Sequence Fusion,Position-Channel Attention,and Dual Enhancement Network).The model integrates the SEAM(Self-Ensembling Attention Mechanism)semantic enhancement module,the MLCA(Mixed Local Channel Attention)lightweight attention mechanism,and the SPA(Scale-Position-Detail Awareness)module composed of SSFF(Scale Sequence Feature Fusion),TFE(Triple Feature Encoding),and CPAM(Channel and Position Attention Mechanism).These enhancements strengthen fine-grained lesion detection while maintaining model lightweightness.Experimental results show that YOLO-SPDNet achieves an accuracy of 91.8%,a recall of 86.5%,and an mAP@0.5 of 90.6%on the test set,with a computational complexity of 12.5 GFLOPs.Furthermore,the model reaches a real-time inference speed of 987 FPS,making it suitable for deployment on mobile agricultural terminals and online monitoring systems.Comparative analysis and ablation studies further validate the reliability and practical applicability of the proposed model in complex natural scenes. 展开更多
关键词 Tomato disease detection YOLO multi-scale feature fusion attention mechanism lightweight model
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DL-YOLO:AMulti-Scale Feature Fusion Detection Algorithm for Low-Light Environments
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作者 Yuanmeng Chang Hongmei Liu 《Computers, Materials & Continua》 2026年第5期1901-1915,共15页
Driven by rapid advances in deep learning,object detection has been widely adopted across diverse application scenarios.However,in low-light conditions,critical visual cues of target objects are severely degraded,posi... Driven by rapid advances in deep learning,object detection has been widely adopted across diverse application scenarios.However,in low-light conditions,critical visual cues of target objects are severely degraded,posing a significant challenge for accurate low-light object detection.Existing methods struggle to preserve discriminative features while maintaining semantic consistency between low-light and normal-light images.For this purpose,this study proposes a DL-YOLO model specially tailored for low-light detection.To mitigate target feature attenuation introduced by repeated downsampling,we design aMulti-Scale FeatureConvolution(MSF-Conv)module that captures rich,multi-level details via multi-scale feature learning,thereby reducing model complexity and computational cost.For feature fusion,we integrated the C3k2-DWRmodule by embedding the Dilation-wise Residual(DWR)mechanism into the 2-core optimized Cross Stage Partial(C3)framework,achieving efficient feature integration.In addition,we replace conventional localization losses with WIoU(Weighted Intersection over Union),which dynamically adjusts gradient gain according to sample quality,thereby improving localization robustness and precision.Experiments on the ExDark dataset demonstrate that DL-YOLO delivers strong low-light detection performance.The relevant code is published at https://github.com/cym0997/DL-YOLO. 展开更多
关键词 multi-scale feature extraction object detection low-light environments ExDark dataset
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Global context-aware multi-scale feature iterative refinement for aviation-road traffic semantic segmentation
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作者 Mengyue ZHANG Shichun YANG +1 位作者 Xinjie FENG Yaoguang CAO 《Chinese Journal of Aeronautics》 2026年第2期429-441,共13页
Semantic segmentation for mixed scenes of aerial remote sensing and road traffic is one of the key technologies for visual perception of flying cars.The State-of-the-Art(SOTA)semantic segmentation methods have made re... Semantic segmentation for mixed scenes of aerial remote sensing and road traffic is one of the key technologies for visual perception of flying cars.The State-of-the-Art(SOTA)semantic segmentation methods have made remarkable achievements in both fine-grained segmentation and real-time performance.However,when faced with the huge differences in scale and semantic categories brought about by the mixed scenes of aerial remote sensing and road traffic,they still face great challenges and there is little related research.Addressing the above issue,this paper proposes a semantic segmentation model specifically for mixed datasets of aerial remote sensing and road traffic scenes.First,a novel decoding-recoding multi-scale feature iterative refinement structure is proposed,which utilizes the re-integration and continuous enhancement of multi-scale information to effectively deal with the huge scale differences between cross-domain scenes,while using a fully convolutional structure to ensure the lightweight and real-time requirements.Second,a welldesigned cross-window attention mechanism combined with a global information integration decoding block forms an enhanced global context perception,which can effectively capture the long-range dependencies and multi-scale global context information of different scenes,thereby achieving fine-grained semantic segmentation.The proposed method is tested on a large-scale mixed dataset of aerial remote sensing and road traffic scenes.The results confirm that it can effectively deal with the problem of large-scale differences in cross-domain scenes.Its segmentation accuracy surpasses that of the SOTA methods,which meets the real-time requirements. 展开更多
关键词 Aviation-road traffic Flying cars Global context-aware multi-scale feature iterative refinement Semantic segmentation
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Multi-scale analysis of spatiotemporal evolution and driving factors of eco-environmental quality in a Ningxia irrigation district,China
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作者 LI Zequan CHAI Mingtang +4 位作者 ZHU Lei HE Junjie DING Yimin XU Fengkun XU Xiyuan 《Journal of Geographical Sciences》 2026年第2期471-493,共23页
The Qingtongxia Irrigation District in Ningxia is an important hydrological and ecological region.To assess its ecological environment quality from 2001 to 2021 across multiple scales and identify driving factors,a mo... The Qingtongxia Irrigation District in Ningxia is an important hydrological and ecological region.To assess its ecological environment quality from 2001 to 2021 across multiple scales and identify driving factors,a modified remote sensing ecological index(MRSEI)was developed by incorporating evapotranspiration.Spatial and temporal patterns were analyzed using the coefficient of variation,spatial autocorrelation,and semi-variogram methods,while influencing factors were explored via the optimal parameter geographical detector model.The MRSEI’s first principal component loadings and rankings aligned with those of RSEI(average contribution:81.31%),effectively reflecting spatiotemporal variations.At sub-irrigation district and landscape scales,ecological quality was slightly lower than at the district level but remained stable.Moderate and good ecological grades accounted for 36.28%and 33.38%of the area,respectively,at the district scale,and the moderate grade reached 70.48%on smaller scales.Spatial heterogeneity intensified with decreasing scale,and human activity lost explanatory power below a 5 km range.Human factors mainly drove ecological differentiation at the district scale,while natural factors dominated at finer scales.The MRSEI offers a novel tool for ecological assessment in arid/semi-arid areas and supports scale-adapted ecological protection strategies. 展开更多
关键词 ecological environment quality multi-scales remote sensing ecological index spatial heterogeneity semi-variance function
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Copper-Catalyzed Asymmetric Oxidative Homocoupling Reaction of 3-Hydroxy-2-naphthoates:Design and Optimization of Amino Acid-Based Ligands
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作者 Wang Wen-Long Wen Jia-Xu +4 位作者 Chen Fei Bo Chunbo Li Min Liu Ning Du Zhi-Hong 《有机化学》 北大核心 2026年第1期167-180,共14页
A series of new chiral amide ligands were prepared from natural amino acids and applied to the copper-catalyzed asymmetric oxidative homocoupling reaction of 3-hydroxy-2-naphthoates.By optimizing the reaction conditio... A series of new chiral amide ligands were prepared from natural amino acids and applied to the copper-catalyzed asymmetric oxidative homocoupling reaction of 3-hydroxy-2-naphthoates.By optimizing the reaction conditions,it was found that when using L3(5 mol%)as the ligand,CuCl(5 mol%)as the catalyst,dichloromethane as the solvent,2,2,6,6-tetramethylpiperidine 1-oxyl(TEMPO)/O2 as the oxidant,and under the reaction condition of 40℃,this method exhibited good substrate tolerance.Under these conditions,a series of chiral 1,1'-bi-2-naphthol(BINOL)derivatives were synthesized with yields of 45%~90%and enantioselectivities ranging from 50∶50 to 97∶3. 展开更多
关键词 chiral amide ligand copper catalyst oxidative coupling 3-hydroxy-2-naphthoate 1 1'-bi-2-naphthol(BINOL)
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A Multi-Scale Graph Neural Networks Ensemble Approach for Enhanced DDoS Detection
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作者 Noor Mueen Mohammed Ali Hayder Seyed Amin Hosseini Seno +2 位作者 Hamid Noori Davood Zabihzadeh Mehdi Ebady Manaa 《Computers, Materials & Continua》 2026年第4期1216-1242,共27页
Distributed Denial of Service(DDoS)attacks are one of the severe threats to network infrastructure,sometimes bypassing traditional diagnosis algorithms because of their evolving complexity.PresentMachine Learning(ML)t... Distributed Denial of Service(DDoS)attacks are one of the severe threats to network infrastructure,sometimes bypassing traditional diagnosis algorithms because of their evolving complexity.PresentMachine Learning(ML)techniques for DDoS attack diagnosis normally apply network traffic statistical features such as packet sizes and inter-arrival times.However,such techniques sometimes fail to capture complicated relations among various traffic flows.In this paper,we present a new multi-scale ensemble strategy given the Graph Neural Networks(GNNs)for improving DDoS detection.Our technique divides traffic into macro-and micro-level elements,letting various GNN models to get the two corase-scale anomalies and subtle,stealthy attack models.Through modeling network traffic as graph-structured data,GNNs efficiently learn intricate relations among network entities.The proposed ensemble learning algorithm combines the results of several GNNs to improve generalization,robustness,and scalability.Extensive experiments on three benchmark datasets—UNSW-NB15,CICIDS2017,and CICDDoS2019—show that our approach outperforms traditional machine learning and deep learning models in detecting both high-rate and low-rate(stealthy)DDoS attacks,with significant improvements in accuracy and recall.These findings demonstrate the suggested method’s applicability and robustness for real-world implementation in contexts where several DDoS patterns coexist. 展开更多
关键词 DDoS detection graph neural networks multi-scale learning ensemble learning network security stealth attacks network graphs
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