Accurately assessing the impact of turbulence structures on load fluctuation is crucial for the long-term stable operation of wind turbines.Based on turbulence signals observed at the Qingtu Lake Observed Array in Chi...Accurately assessing the impact of turbulence structures on load fluctuation is crucial for the long-term stable operation of wind turbines.Based on turbulence signals observed at the Qingtu Lake Observed Array in China,the aerodynamic load responses of the wind turbine to different turbulence scales are quantitatively analyzed in this study.The results indicate that very large-scale motions(VLSMs)are associated with significant load fluctuations due to its low frequency and high energy characteristics,increasing the risk of extreme loads.Large-scale motions coupled with the natural frequency of wind turbines in the medium frequency range,result in resonance phenomena.Small-scale motions,due to their high-frequency rapid vibration characteristics,cause instantaneous oscillations in wind turbine loads.Furthermore,correlation analysis indicates that the flapwise moment and thrust are most sensitive to VLSMs,while the edgewise moment is less affected by the scale characteristics.It is worth noting that this study is the first to explore the modulation effects of different scales of turbulent structures on the amplitude of wind turbine load fluctuation.It was found that turbulent structures exceeding a scale of 3δ have the most significant impact on modulating the load amplitudes,where δ is the boundary layer thickness,which is 99% of the flow velocity outside the boundary layer.These findings contribute to the enhancement of understanding regarding the load response of wind turbines in multi-scale turbulent environments and provide important references for the optimization of wind turbine design and load control.展开更多
The multi-scale Ti2AlC/TiAl composites were fabricated.Micro-Ti2AlC particles are obtained in-situ at the grain boundaries of the full lamellar TiAl matrix by vacuum arc melting.The targeted precipitation of sub...The multi-scale Ti2AlC/TiAl composites were fabricated.Micro-Ti2AlC particles are obtained in-situ at the grain boundaries of the full lamellar TiAl matrix by vacuum arc melting.The targeted precipitation of submicro-Ti2AlC at the lamellae TiAl/Ti3Al phase boundary and directional precipitation of nano-Ti2AlC within TiAl crystals are achieved by heat treatment.And the best high-temperature tensile properties are obtained when the graphite powder is added at 2 at.%,resulting in a tensile strength of 561 MPa and an elongation of 3.6%.These findings underscore the multifaceted role played by the multi-scale Ti2AlC:micro-Ti2AlC effectively inhibits grain boundary softening and hinders dislocation motion,while submicro-Ti2AlC prevents twin propagation and obstructs dislocation motion.Nano-Ti2AlC,on the other hand,not only hinders dislocation movement but also fine-tunes the lamellar microstructure.展开更多
Heterostructured materials as a new class can effectively avoid the inverted relationship of the“banana”curve followed by strength-ductility.The difference in grain size is the mainstream idea of the design of heter...Heterostructured materials as a new class can effectively avoid the inverted relationship of the“banana”curve followed by strength-ductility.The difference in grain size is the mainstream idea of the design of heterogeneous zones.However,the synergistic strengthening mechanism and deformation behavior among multi-scale heterostructures are still unclear.In this work,AZ80/AZ31 laminate with a multi-scale heterogeneous distribution of grain size,precipitates,and texture between alternate AZ31 and AZ80 component layers,which was constructed by accumulative extrusion bonding combined with aging treatment.The composite samples after 2-pass extrusion presented an outstanding strength-ductility synergy,which was attributed to the joint action of texture softening and hardening,grain refinement as well as multistage heterogeneous deformation induced(HDI)strengthening and hardening.Multi-types of heterogeneous regions provided more sites for geometrically necessary dislocation accumulation to accommodate multiple strain gradients under the constraint of multi-layer interfaces,enhancing HDI stress.The synergistic effect of great Schmid factor difference and increasing geometric compatibility factor between adjacent grains at the layer interface led to strain transfer behavior,which facilitated strain delocalization.This work expands the design ideas and preparation methods of heterostructured materials and enriches the theory of heterogeneous deformation.展开更多
Flexible pressure sensors have excellent prospects in applications of human-machine interfaces,artificial intelligence and human health monitoring due to their bendable and lightweight characteristics compared to rigi...Flexible pressure sensors have excellent prospects in applications of human-machine interfaces,artificial intelligence and human health monitoring due to their bendable and lightweight characteristics compared to rigid pressure sensors.However,arising from the limited compressibility of soft materials and the hardening of microstructures at the device interface,there is always a trade-off between high sensitivity and broad sensing range for most flexible pressure sensors,which results in a gradual saturation response and limits their practical applications.Herein,inspired by the distinct pressure perception function of crocodile receptors,a highly sensitive and wide-range flexible pressure sensor with multiscale microdomes and interlocked architecture is developed via a facile PS-decorated molding method.Combined with interlocked architecture,the multiscale dome-shaped structured interface enhances the compressibility of the material through structural complementarity,increases the contact area between functional materials,which compensates for the stiffness induced by the deformation of dense microscale columns.This effectively mitigates structural hardening across a wide pressure range,leading to the overall high performance of the sensor.As a result,the obtained sensor exhibits a low detection limit of 5 Pa,a high sensitivity of 6.14 kPa-1,a wide measurement range up to 231 kPa,short responseecovery time of 56 ms/69 ms,outstanding stability over 10,000 cycles.Considering these excellent properties,the sensor shows promising potential in health monitoring,human-computer interaction,wearable electronics.This study presents a strategy for the fabrication of flexible pressure sensors exhibiting high sensitivity and a wide pressure response range.展开更多
The development of metallic mineral resources generates a significant amount of solid waste,such as tailings and waste rock.Cemented tailings and waste-rock backfill(CTWB)is an effective method for managing and dispos...The development of metallic mineral resources generates a significant amount of solid waste,such as tailings and waste rock.Cemented tailings and waste-rock backfill(CTWB)is an effective method for managing and disposing of this mining waste.This study employs a macro-meso-micro testing method to investigate the effects of the waste rock grading index(WGI)and loading rate(LR)on the uniaxial compressive strength(UCS),pore structure,and micromorphology of CTWB materials.Pore structures were analyzed using scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP).The particles(pores)and cracks analysis system(PCAS)software was used to quantitatively characterize the multi-scale micropores in the SEM images.The key findings indicate that the macroscopic results(UCS)of CTWB materials correspond to the microscopic results(pore structure and micromorphology).Changes in porosity largely depend on the conditions of waste rock grading index and loading rate.The inclusion of waste rock initially increases and then decreases the UCS,while porosity first decreases and then increases,with a critical waste rock grading index of 0.6.As the loading rate increases,UCS initially rises and then falls,while porosity gradually increases.Based on MIP and SEM results,at waste rock grading index 0.6,the most probable pore diameters,total pore area(TPA),pore number(PN),maximum pore area(MPA),and area probability distribution index(APDI)are minimized,while average pore form factor(APF)and fractal dimension of pore porosity distribution(FDPD)are maximized,indicating the most compact pore structure.At a loading rate of 12.0 mm/min,the most probable pore diameters,TPA,PN,MPA,APF,and APDI reach their maximum values,while FDPD reaches its minimum value.Finally,the mechanism of CTWB materials during compression is analyzed,based on the quantitative results of UCS and porosity.The research findings play a crucial role in ensuring the successful application of CTWB materials in deep metal mines.展开更多
UHMWPE(Ultra-High Molecular Weight Polyethylene)plain-weave fabric,characterized by its lightweight and high-strength properties,is widely used in protective equipment such as bulletproof vests and stab-resistant vest...UHMWPE(Ultra-High Molecular Weight Polyethylene)plain-weave fabric,characterized by its lightweight and high-strength properties,is widely used in protective equipment such as bulletproof vests and stab-resistant vests,serving as a key material for enhancing protective performance.This study systematically investigates the influence mechanism of interfacial properties on the energy absorption characteristics of UHMWPE-based protective structures through multi-scale experiments and numerical simulations,and establishes a cross-scale design methodology.Innovatively,an orthotropic constitutive model incorporating dynamic friction coefficients is constructed,combined with a modified Johnson-Cook failure criterion,to achieve high-precision simulation of the entire ballistic impact process(error<3.5%).Additionally,a friction field prediction model considering strain rate effects is developed,and the friction evolution laws of UHMWPE and Para-aramid(Kevlar)fabrics under strain rates of 10−3 and 10−4 s−1 are obtained through MTS pull-out tests.The results show that:(1)there exists a critical yarn-yarn friction coefficient(μ=0.2);exceeding this value leads to a 19%reduction in energy absorption capacity,while viscous interfaces increase the energy dissipation peak by 16%;(2)UHMWPE shows kinetically-dominated absorption(58%)with high rate but high load,increasing damage risk.Para-aramid has friction-dominated absorption(53%)with a lower rate but stable load.Hybrid fabrics use potential-dominated absorption(49%)at a moderate rate,balancing stability and protection.(3)3–5 layers of UHMWPE fabric yield optimal cost-effectiveness,with the unit cost reduction rate of the HS+5U scheme reaching 2.74 m/(s·$),which is 91%higher than that of the hybrid scheme.(4)For HS+5U(5-ply UHMWPE),V50 is 520 m/s,meeting primary protection requirement.For hybrid solutions with U/K≥3(e.g.,HS+6U+2K),V50 reaches 580 m/s(≥540 m/s),satisfying advanced protection requirement.This research provides critical references for the design of flexible protective structures and their engineering applications.展开更多
Materials constituting satellites in the Low Earth Orbit(LEO)environment undergo degradation during missions due to harsh conditions such as cyclic temperature variations in high-vacuum,exposure to UV radiation,and co...Materials constituting satellites in the Low Earth Orbit(LEO)environment undergo degradation during missions due to harsh conditions such as cyclic temperature variations in high-vacuum,exposure to UV radiation,and collisions with highly reactive Atomic Oxygens(AO).Especially among those,AO collisions oxidize the surface and induce mass loss by generating volatile gases,leading to component failure.Reactive Force Field(Reax FF)molecular dynamics simulations,capable of describing chemical reactions,have been continuously performed to evaluate the AO erosion resistance of surface materials in LEO.Previous molecular simulation-based studies,however,evaluated AO resistance qualitatively by utilizing constant particle Number,Volume,Energy(NVE)ensemble simulations,where temperatures rise to several thousand kelvins over tens of picoseconds,and such extreme temperature conditions were not directly compatible with physical conditions in LEO.Therefore,we aimed to develop a multi-scale AO erosion analysis bridging thermal Finite Element Analysis(FEA)with mass loss rate determined from the Reax FF MD simulations.The overall thermal analysis was conducted over solar heat flux and surface radiation,while the ABAQUS Umeshmotion and Arbitrary Lagrangian-Eulerian(ALE)algorithm was adopted to analyze the surface recession of the model.The relation between erosion yields in given temperature conditions was calculated using constant particle Number,Volume,Temperature(NVT)ensemble,fitted as the Arrhenius equation form,and implemented to the FEA simulations.展开更多
Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimizat...Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimization method grounded in the global adjustment of nodal coordinates.First,a build direction is selected to minimize the number of violating struts.Then,an angular-constraint matrix is assembled from strut direction vectors,and analytical sensitivities with respect to nodal coordinates are derived to enable efficient constrained optimization under nonlinear angular inequality constraints.Numerical studies on two complex curved-surface lattices demonstrate that all overhang violations are eliminated while only minor changes are induced in global stiffness and strength.In particular,the maximum displacement of an ergonomic insole varies by only 2.87%after optimization.The results confirm the method’s versatility and engineering robustness,providing a practical approach for additive manufacturing-oriented lattice structure design.展开更多
This study presents a multi-scale modeling framework to describe the mechanical behavior of a 0.1 mm-thick commercially pure titanium(CP-Ti)sheet developed for fuel cell bipolar plates.Since standardized methods for c...This study presents a multi-scale modeling framework to describe the mechanical behavior of a 0.1 mm-thick commercially pure titanium(CP-Ti)sheet developed for fuel cell bipolar plates.Since standardized methods for characterizing ultra-thin sheets under complex stress states are lacking,a virtual modeling approach was employed.At the grain scale,a crystal plasticity finite element(CPFE)model was constructed to incorporate the relevant slip and twinning systems,enabling prediction of responses under diverse loading conditions.Extending to the continuum scale,the CPFE results,combined with tensile data,were used to calibrate an advanced constitutive model based on the evolutionary Yld2000-2d yield function,capable of capturing anisotropic behavior.Validation against independent limiting dome height tests confirmed the predictive accuracy of the framework.The proposed approach provides a basis for simulating the forming behavior of ultra-thin CP-Ti sheets and supports precise manufacturing of bipolar plates in fuel cell systems.展开更多
Improving the volumetric energy density of supercapacitors is essential for practical applications,which highly relies on the dense storage of ions in carbon-based electrodes.The functional units of carbon-based elect...Improving the volumetric energy density of supercapacitors is essential for practical applications,which highly relies on the dense storage of ions in carbon-based electrodes.The functional units of carbon-based electrode exhibit multi-scale structural characteristics including macroscopic electrode morphologies,mesoscopic microcrystals and pores,and microscopic defects and dopants in the carbon basal plane.Therefore,the ordered combination of multi-scale structures of carbon electrode is crucial for achieving dense energy storage and high volumetric performance by leveraging the functions of various scale structu re.Considering that previous reviews have focused more on the discussion of specific scale structu re of carbon electrodes,this review takes a multi-scale perspective in which recent progresses regarding the structureperformance relationship,underlying mechanism and directional design of carbon-based multi-scale structures including carbon morphology,pore structure,carbon basal plane micro-environment and electrode technology on dense energy storage and volumetric property of supercapacitors are systematically discussed.We analyzed in detail the effects of the morphology,pore,and micro-environment of carbon electrode materials on ion dense storage,summarized the specific effects of different scale structures on volumetric property and recent research progress,and proposed the mutual influence and trade-off relationship between various scale structures.In addition,the challenges and outlooks for improving the dense storage and volumetric performance of carbon-based supercapacitors are analyzed,which can provide feasible technical reference and guidance for the design and manufacture of dense carbon-based electrode materials.展开更多
Advanced chemical engineering for simultaneous modulation of nanomaterial morphology, defects, interfaces, and structure to enhance electromagnetic and microwave absorption (MA) performance. However, accurately distin...Advanced chemical engineering for simultaneous modulation of nanomaterial morphology, defects, interfaces, and structure to enhance electromagnetic and microwave absorption (MA) performance. However, accurately distinguishing the MA contributions of different scale factors and tuning the optimal combined effects remains a formidable challenge. This study employs a synergistic approach combining template protection etching and vacuum annealing to construct a controlled system of micrometer-sized cavities and amorphous carbon matrices in metal-organic framework (MOF) derivatives. The results demonstrate that the spatial effects introduced by the hollow structure enhance dielectric loss but significantly weaken impedance matching. By increasing the proportion of amorphous carbon, the balance between electromagnetic loss and impedance matching can be effectively maintained. Importantly, in a suitable graphitization environment, the presence of oxygen vacancies in amorphous carbon can induce significant polarization to compensate for the reduced conductivity loss due to the absence of sp2 carbon. Through the synergistic effects of morphology and composition, the samples exhibit a broader absorption bandwidth (6.28 GHz) and stronger reflection loss (−61.64 dB) compared to the original MOF. In conclusion, this study aims to elucidate the multiscale impacts of macroscopic micro-nano structure and microscopic defect engineering, providing valuable insights for future research in this field.展开更多
Ceramic materials demonstrate great application potential in multiple fields such as aerospace and biomedical engineering due to their excellent mechanical properties,high-temperature resistance,and good biocompatibil...Ceramic materials demonstrate great application potential in multiple fields such as aerospace and biomedical engineering due to their excellent mechanical properties,high-temperature resistance,and good biocompatibility,but their inherent brittleness and processing defects urgently need to be broken through.Inspired by the biological structures found in nature,the integration of biomimicry and additive manufacturing(AM)technologies offers a new pathway for the innovative design of high-performance ceramic materials.This article systematically reviews the fundamental principles and classifications of ceramic AM technology,focusing on six typical elements of biomimetic structural design:coaxial composite structures,surface reinforcement structures,layered composite structures,porous structures,composite multicomponent structures,and intelligent bionic structures.The review delves into their biomimetic principles,preparation strategies,performance advantages,and research progress.Research indicates that through multiscale topological design and functional integration,these structures can significantly enhance the mechanical properties and environmental adaptability of ceramics.Nevertheless,current technologies still face numerous challenges in balancing manufacturing precision and efficiency,controlling cracks and residual stresses caused by interface defects,ensuring long-term material stability under extreme environments,enhancing intelligent response capabilities,and guaranteeing process scalability and performance consistency in clinical applications.Future research should integrate multidisciplinary approaches to optimize structural design and dynamic response,transforming biomimetic ceramic materials from‘biological replication'to‘performance exceeding',thereby providing theoretical and technical support for the customized development of high-performance ceramic devices.展开更多
Ocean bottom pressure(OBP)reflects ocean dynamics,thermodynamics,and Earth’s gravity field,playing a key role in physical oceanography and in reducing aliasing errors in satellite gravimetry.Due to limited observatio...Ocean bottom pressure(OBP)reflects ocean dynamics,thermodynamics,and Earth’s gravity field,playing a key role in physical oceanography and in reducing aliasing errors in satellite gravimetry.Due to limited observations,highfrequency global OBP studies rely on numerical models,which inherently contain uncertainties.This study employs the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics(LASG/IAP)Climate System Ocean Model version 3.0(LICOM3.0)to simulate global OBP from 2002 to 2018,driven by two different atmospheric reanalysis datasets.Validation against in situ observations shows that LICOM3.0 effectively captures sub-seasonal OBP variability(1–30 d)at the available stations,which are located in the Pacific and along the Atlantic coast.Compared to another ocean model,LICOM3.0 reproduces similar OBP patterns for periods longer than 1 d and spatial scales greater than 500 km,demonstrating its capability for large-scale OBP analysis and assessing inter-model uncertainty.However,the model underestimates OBP amplitudes,and exhibits marked discrepancies at sub-daily periods,in marginal seas,and on spatial scales below 500 km with reference data.These issues are consistent across both experiments,indicating that model configuration contributes to the limitations.Potential sources of error are discussed to support future model improvements.Overall,LICOM3.0 can serve as an effective tool for oceanic scientific applications and for de-aliasing in satellite gravimetry applications.展开更多
Voronoi structures are widely present in nature,and highly ordered Voronoi structures such as honeycomb structures have gained extensive recognition and in-depth research in the field of sound absorption structure des...Voronoi structures are widely present in nature,and highly ordered Voronoi structures such as honeycomb structures have gained extensive recognition and in-depth research in the field of sound absorption structure design.However,Voronoi structures in biological tissues are not all highly ordered.Stochastic Voronoi structures are equally prevalent and exhibit excellent multifunctional properties.To further explore the acoustic value of stochastic Voronoi structures,this study proposes a Voronoi sound absorbing porous structure that features both structural stochasticity and performance robustness.First,a theoretical calculation model is established based on microperforated panel theory and Helmholtz resonance theory,enabling the rapid calculation of the structure’s sound absorption coefficient.Then,a systematic analysis is conducted on the effective conditions for absorption performance robustness from four dimensions:unit number,structural randomness,manufacturing errors,and boundary cutting.Results indicate that there exists a unit number threshold associated with absorption bandwidth in the Voronoi structure.When this threshold is exceeded,the structure can exhibit favorable sound absorption robustness against structural stochasticity,manufacturing errors,and boundary cutting.Experimental verification shows that under significant boundary changes,the structure still maintains an average sound absorption coefficient of approximately 0.8 within an absorption bandwidth of approximately 400 Hz.Its favorable low-frequency broadband sound absorption performance and robustness endow it with promising application prospects in engineering fields where cost control,environmental adaptability,and construction efficiency need to be balanced.展开更多
Detecting keypoints in dairy cows aims to locate and track the motion trajectories of the body's joints,which plays a crucial role in behavior analysis and lameness detection.However,real farming scenarios,charact...Detecting keypoints in dairy cows aims to locate and track the motion trajectories of the body's joints,which plays a crucial role in behavior analysis and lameness detection.However,real farming scenarios,characterized by occlusions and large variations in object scale may result in poor detection results.Therefore,we introduce the atrous spatial pyramid pooling(ASPP) module into the shallow layers network of ResNet101,designed to improve the multi-scale feature extraction capability of the model.The ASPP module enhances the robustness of recognition for different dimensional sizes and occluded keypoints using different dilatation rates in the parallel atrous convolutional layers to expand the model's receptive field.Furthermore,seven types of motion features,including tracking up,gait symmetry,step height balance,motion speed variability,head swing amplitude,head-neck slope and back curvature are extracted simultaneously by monitoring and tracking the motion trajectory of distinct keypoints.Several of these features represent innovative extraction models and attributes,first proposed in this study.Multiple models are trained and tested on datasets containing 2,385 frames for ablation experiments.The experiments show that,in comparison with the ResNet50,MobileNet_v2_1.0,and EfficientNet-b0backbone networks,the training error and test error of ResNet101 are reduced by 4.04-30.12 pixels and 3.81-28.14 pixels.Therefore,ResNet101 is used as the benchmark for subsequent model improvement by adding the ASPP module.The training error and test error of the ResNet101-ASPP network are reduced by 0.27 and 0.24 pixels,respectively,compared to the benchmark network.The prediction confidence improves by 1.65-2.50% at three different dairy cow object scales.In addition,the keypoints under different occlusion conditions improve considerably,especially for small-scale keypoints,demonstrating the capability of the ASPP module for multi-scale feature extraction.By analyzing the distribution of the seven features and health,mild lameness,and severe lameness in dairy cows,it is shown that all the different features play an important role in distinguishing between different levels of lameness.展开更多
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
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
Accurately characterizing the distribution and scale characteristics of fractures in subsurface media is a crucial step for quantitatively evaluating shale gas sweet spots and guiding reservoir fracturing stimulation....Accurately characterizing the distribution and scale characteristics of fractures in subsurface media is a crucial step for quantitatively evaluating shale gas sweet spots and guiding reservoir fracturing stimulation.However,a single seismic attribute is often used to identify fracture features of a specifi c scale,making it diffi cult to achieve detailed characterization of fractures across multiple scales simultaneously.Multi-attribute fusion algorithms often focus on statistical correlations,lacking in-depth exploration of the spatial topological relationships and intrinsic physical connections among fractures of diff erent scales,resulting in reduced accuracy in complex structural areas.To address this challenge,we propose a multi-scale integrated fracture prediction method based on an improved deep embedded clustering(DEC)framework,using the marine shale reservoir of the Wufeng–Longmaxi Formation in southeastern Sichuan Basin as a case study.Specifically,(1)an improved DEC objective function integrating fracture topology constraints and cluster-balancing mechanisms is developed to enhance the model’s adaptability to complex geological structures;(2)an“expand–then–contract”stacked autoencoder architecture is designed to better capture nonlinear relationships among multi-attribute data and decouple multi-scale fracture features;and(3)an integrated workfl ow from multi-attribute optimization,intelligent fusion clustering to geological interpretation is established,enabling diff erentiated and high-precision characterization of multi-scale fractures.Furthermore,based on the geological characteristics of the study area,we systematically analyze the spatial mapping relationships of the autoencoder’s multi-layer features and elucidate their implicit geophysical signifi cance.This analysis reveals the intrinsic processes through which the proposed model performs fracture attribute optimization,noise separation,and multi-scale feature extraction.Finally,by integrating intelligent fault identifi cation,micro-fracture amplitude variation with azimuth(AVAZ)inversion,and conventional geometric attributes,high-precision spatial characterization of the fracture system is achieved,spanning from large-scale faults to micro-fractures.The prediction results show strong agreement with geological understanding.展开更多
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
基金supported by the National Natural Science Foundation of China(Grant Nos.52276197 and 52166014).
摘要Accurately assessing the impact of turbulence structures on load fluctuation is crucial for the long-term stable operation of wind turbines.Based on turbulence signals observed at the Qingtu Lake Observed Array in China,the aerodynamic load responses of the wind turbine to different turbulence scales are quantitatively analyzed in this study.The results indicate that very large-scale motions(VLSMs)are associated with significant load fluctuations due to its low frequency and high energy characteristics,increasing the risk of extreme loads.Large-scale motions coupled with the natural frequency of wind turbines in the medium frequency range,result in resonance phenomena.Small-scale motions,due to their high-frequency rapid vibration characteristics,cause instantaneous oscillations in wind turbine loads.Furthermore,correlation analysis indicates that the flapwise moment and thrust are most sensitive to VLSMs,while the edgewise moment is less affected by the scale characteristics.It is worth noting that this study is the first to explore the modulation effects of different scales of turbulent structures on the amplitude of wind turbine load fluctuation.It was found that turbulent structures exceeding a scale of 3δ have the most significant impact on modulating the load amplitudes,where δ is the boundary layer thickness,which is 99% of the flow velocity outside the boundary layer.These findings contribute to the enhancement of understanding regarding the load response of wind turbines in multi-scale turbulent environments and provide important references for the optimization of wind turbine design and load control.
基金supported by the Open Research Fund of State Key Laboratory of Advanced Casting Technologies,China(No.CAT2023-007)Key Research and Development Program in Henan Province,China(No.242102230059)the National Natural Science Foundation of China(No.52101174).
摘要The multi-scale Ti2AlC/TiAl composites were fabricated.Micro-Ti2AlC particles are obtained in-situ at the grain boundaries of the full lamellar TiAl matrix by vacuum arc melting.The targeted precipitation of submicro-Ti2AlC at the lamellae TiAl/Ti3Al phase boundary and directional precipitation of nano-Ti2AlC within TiAl crystals are achieved by heat treatment.And the best high-temperature tensile properties are obtained when the graphite powder is added at 2 at.%,resulting in a tensile strength of 561 MPa and an elongation of 3.6%.These findings underscore the multifaceted role played by the multi-scale Ti2AlC:micro-Ti2AlC effectively inhibits grain boundary softening and hinders dislocation motion,while submicro-Ti2AlC prevents twin propagation and obstructs dislocation motion.Nano-Ti2AlC,on the other hand,not only hinders dislocation movement but also fine-tunes the lamellar microstructure.
基金financially supported by the National Natural Science Foundation of China(No.52071035)the Doctoral Scientific Research Foundation of Anhui University of Technology(No.RZ2400002557).
摘要Heterostructured materials as a new class can effectively avoid the inverted relationship of the“banana”curve followed by strength-ductility.The difference in grain size is the mainstream idea of the design of heterogeneous zones.However,the synergistic strengthening mechanism and deformation behavior among multi-scale heterostructures are still unclear.In this work,AZ80/AZ31 laminate with a multi-scale heterogeneous distribution of grain size,precipitates,and texture between alternate AZ31 and AZ80 component layers,which was constructed by accumulative extrusion bonding combined with aging treatment.The composite samples after 2-pass extrusion presented an outstanding strength-ductility synergy,which was attributed to the joint action of texture softening and hardening,grain refinement as well as multistage heterogeneous deformation induced(HDI)strengthening and hardening.Multi-types of heterogeneous regions provided more sites for geometrically necessary dislocation accumulation to accommodate multiple strain gradients under the constraint of multi-layer interfaces,enhancing HDI stress.The synergistic effect of great Schmid factor difference and increasing geometric compatibility factor between adjacent grains at the layer interface led to strain transfer behavior,which facilitated strain delocalization.This work expands the design ideas and preparation methods of heterostructured materials and enriches the theory of heterogeneous deformation.
基金supported by the National Natural Science Foundation of China(No.52175269)the Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+2 种基金Natural Science Foundation of Jilin Province of China(No.20210101052JC)Science and Technology Research Project of Education Department of Jilin Province(JJKH20231146KJ,JJKH20241262KJ)China Postdoctoral Science Foundation(2024M751086).
摘要Flexible pressure sensors have excellent prospects in applications of human-machine interfaces,artificial intelligence and human health monitoring due to their bendable and lightweight characteristics compared to rigid pressure sensors.However,arising from the limited compressibility of soft materials and the hardening of microstructures at the device interface,there is always a trade-off between high sensitivity and broad sensing range for most flexible pressure sensors,which results in a gradual saturation response and limits their practical applications.Herein,inspired by the distinct pressure perception function of crocodile receptors,a highly sensitive and wide-range flexible pressure sensor with multiscale microdomes and interlocked architecture is developed via a facile PS-decorated molding method.Combined with interlocked architecture,the multiscale dome-shaped structured interface enhances the compressibility of the material through structural complementarity,increases the contact area between functional materials,which compensates for the stiffness induced by the deformation of dense microscale columns.This effectively mitigates structural hardening across a wide pressure range,leading to the overall high performance of the sensor.As a result,the obtained sensor exhibits a low detection limit of 5 Pa,a high sensitivity of 6.14 kPa-1,a wide measurement range up to 231 kPa,short responseecovery time of 56 ms/69 ms,outstanding stability over 10,000 cycles.Considering these excellent properties,the sensor shows promising potential in health monitoring,human-computer interaction,wearable electronics.This study presents a strategy for the fabrication of flexible pressure sensors exhibiting high sensitivity and a wide pressure response range.
基金Project(2022YFC2904103)supported by the National Key Research and Development Program of ChinaProjects(52374112,52274108)supported by the National Natural Science Foundation of China+1 种基金Projects(BX20220036,BX20230041)supported by the Postdoctoral Innovation Talents Support Program,ChinaProject(2232080)supported by the Beijing Natural Science Foundation,China。
摘要The development of metallic mineral resources generates a significant amount of solid waste,such as tailings and waste rock.Cemented tailings and waste-rock backfill(CTWB)is an effective method for managing and disposing of this mining waste.This study employs a macro-meso-micro testing method to investigate the effects of the waste rock grading index(WGI)and loading rate(LR)on the uniaxial compressive strength(UCS),pore structure,and micromorphology of CTWB materials.Pore structures were analyzed using scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP).The particles(pores)and cracks analysis system(PCAS)software was used to quantitatively characterize the multi-scale micropores in the SEM images.The key findings indicate that the macroscopic results(UCS)of CTWB materials correspond to the microscopic results(pore structure and micromorphology).Changes in porosity largely depend on the conditions of waste rock grading index and loading rate.The inclusion of waste rock initially increases and then decreases the UCS,while porosity first decreases and then increases,with a critical waste rock grading index of 0.6.As the loading rate increases,UCS initially rises and then falls,while porosity gradually increases.Based on MIP and SEM results,at waste rock grading index 0.6,the most probable pore diameters,total pore area(TPA),pore number(PN),maximum pore area(MPA),and area probability distribution index(APDI)are minimized,while average pore form factor(APF)and fractal dimension of pore porosity distribution(FDPD)are maximized,indicating the most compact pore structure.At a loading rate of 12.0 mm/min,the most probable pore diameters,TPA,PN,MPA,APF,and APDI reach their maximum values,while FDPD reaches its minimum value.Finally,the mechanism of CTWB materials during compression is analyzed,based on the quantitative results of UCS and porosity.The research findings play a crucial role in ensuring the successful application of CTWB materials in deep metal mines.
基金the Postdoctoral Science Foundation Funded Project of China with grant No.2021M701687Introduction and Education Plan for Young Innovative Talents in Colleges and Universities of Shandong Province.
摘要UHMWPE(Ultra-High Molecular Weight Polyethylene)plain-weave fabric,characterized by its lightweight and high-strength properties,is widely used in protective equipment such as bulletproof vests and stab-resistant vests,serving as a key material for enhancing protective performance.This study systematically investigates the influence mechanism of interfacial properties on the energy absorption characteristics of UHMWPE-based protective structures through multi-scale experiments and numerical simulations,and establishes a cross-scale design methodology.Innovatively,an orthotropic constitutive model incorporating dynamic friction coefficients is constructed,combined with a modified Johnson-Cook failure criterion,to achieve high-precision simulation of the entire ballistic impact process(error<3.5%).Additionally,a friction field prediction model considering strain rate effects is developed,and the friction evolution laws of UHMWPE and Para-aramid(Kevlar)fabrics under strain rates of 10−3 and 10−4 s−1 are obtained through MTS pull-out tests.The results show that:(1)there exists a critical yarn-yarn friction coefficient(μ=0.2);exceeding this value leads to a 19%reduction in energy absorption capacity,while viscous interfaces increase the energy dissipation peak by 16%;(2)UHMWPE shows kinetically-dominated absorption(58%)with high rate but high load,increasing damage risk.Para-aramid has friction-dominated absorption(53%)with a lower rate but stable load.Hybrid fabrics use potential-dominated absorption(49%)at a moderate rate,balancing stability and protection.(3)3–5 layers of UHMWPE fabric yield optimal cost-effectiveness,with the unit cost reduction rate of the HS+5U scheme reaching 2.74 m/(s·$),which is 91%higher than that of the hybrid scheme.(4)For HS+5U(5-ply UHMWPE),V50 is 520 m/s,meeting primary protection requirement.For hybrid solutions with U/K≥3(e.g.,HS+6U+2K),V50 reaches 580 m/s(≥540 m/s),satisfying advanced protection requirement.This research provides critical references for the design of flexible protective structures and their engineering applications.
基金financially supported by the Institute of Civil-Military Technology Cooperationfunded by the Defense Acquisition Program Administration and the Ministryof Trade,Industry,and Energy of the Korean Government(No.22-CM-19)。
摘要Materials constituting satellites in the Low Earth Orbit(LEO)environment undergo degradation during missions due to harsh conditions such as cyclic temperature variations in high-vacuum,exposure to UV radiation,and collisions with highly reactive Atomic Oxygens(AO).Especially among those,AO collisions oxidize the surface and induce mass loss by generating volatile gases,leading to component failure.Reactive Force Field(Reax FF)molecular dynamics simulations,capable of describing chemical reactions,have been continuously performed to evaluate the AO erosion resistance of surface materials in LEO.Previous molecular simulation-based studies,however,evaluated AO resistance qualitatively by utilizing constant particle Number,Volume,Energy(NVE)ensemble simulations,where temperatures rise to several thousand kelvins over tens of picoseconds,and such extreme temperature conditions were not directly compatible with physical conditions in LEO.Therefore,we aimed to develop a multi-scale AO erosion analysis bridging thermal Finite Element Analysis(FEA)with mass loss rate determined from the Reax FF MD simulations.The overall thermal analysis was conducted over solar heat flux and surface radiation,while the ABAQUS Umeshmotion and Arbitrary Lagrangian-Eulerian(ALE)algorithm was adopted to analyze the surface recession of the model.The relation between erosion yields in given temperature conditions was calculated using constant particle Number,Volume,Temperature(NVT)ensemble,fitted as the Arrhenius equation form,and implemented to the FEA simulations.
基金supported by the National Natural Science Foundation of China(Grant Nos.12432005 and 12472116)the Fundamental Research Funds for the Central Universities(DUTZD25240).
摘要Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimization method grounded in the global adjustment of nodal coordinates.First,a build direction is selected to minimize the number of violating struts.Then,an angular-constraint matrix is assembled from strut direction vectors,and analytical sensitivities with respect to nodal coordinates are derived to enable efficient constrained optimization under nonlinear angular inequality constraints.Numerical studies on two complex curved-surface lattices demonstrate that all overhang violations are eliminated while only minor changes are induced in global stiffness and strength.In particular,the maximum displacement of an ergonomic insole varies by only 2.87%after optimization.The results confirm the method’s versatility and engineering robustness,providing a practical approach for additive manufacturing-oriented lattice structure design.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00338965)financial support from the Fundamental Research Program of the Korea Institute of Materials Science(No.PNKA300/PNKA730)。
摘要This study presents a multi-scale modeling framework to describe the mechanical behavior of a 0.1 mm-thick commercially pure titanium(CP-Ti)sheet developed for fuel cell bipolar plates.Since standardized methods for characterizing ultra-thin sheets under complex stress states are lacking,a virtual modeling approach was employed.At the grain scale,a crystal plasticity finite element(CPFE)model was constructed to incorporate the relevant slip and twinning systems,enabling prediction of responses under diverse loading conditions.Extending to the continuum scale,the CPFE results,combined with tensile data,were used to calibrate an advanced constitutive model based on the evolutionary Yld2000-2d yield function,capable of capturing anisotropic behavior.Validation against independent limiting dome height tests confirmed the predictive accuracy of the framework.The proposed approach provides a basis for simulating the forming behavior of ultra-thin CP-Ti sheets and supports precise manufacturing of bipolar plates in fuel cell systems.
基金funded by the Joint Fund for Regional Innovation and Development of National Natural Science Foundation of China(U21A20143)the National Science Fund for Excellent Young Scholars(52322607)the Excellent Youth Foundation of Heilongjiang Scientific Committee(YQ2022E028)。
摘要Improving the volumetric energy density of supercapacitors is essential for practical applications,which highly relies on the dense storage of ions in carbon-based electrodes.The functional units of carbon-based electrode exhibit multi-scale structural characteristics including macroscopic electrode morphologies,mesoscopic microcrystals and pores,and microscopic defects and dopants in the carbon basal plane.Therefore,the ordered combination of multi-scale structures of carbon electrode is crucial for achieving dense energy storage and high volumetric performance by leveraging the functions of various scale structu re.Considering that previous reviews have focused more on the discussion of specific scale structu re of carbon electrodes,this review takes a multi-scale perspective in which recent progresses regarding the structureperformance relationship,underlying mechanism and directional design of carbon-based multi-scale structures including carbon morphology,pore structure,carbon basal plane micro-environment and electrode technology on dense energy storage and volumetric property of supercapacitors are systematically discussed.We analyzed in detail the effects of the morphology,pore,and micro-environment of carbon electrode materials on ion dense storage,summarized the specific effects of different scale structures on volumetric property and recent research progress,and proposed the mutual influence and trade-off relationship between various scale structures.In addition,the challenges and outlooks for improving the dense storage and volumetric performance of carbon-based supercapacitors are analyzed,which can provide feasible technical reference and guidance for the design and manufacture of dense carbon-based electrode materials.
基金supported by the National Natural Science Foundation of China(52172091,52172295)Defense Industrial Technology Development Program(JCKY2023605C002)+4 种基金Frontier Leading Technology Basic Research Major Project of Jiangsu Province(SBK2023050110)the National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering(NO.61422062301)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(ZHD202305)the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(ASMA202303)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX23_0371).
摘要Advanced chemical engineering for simultaneous modulation of nanomaterial morphology, defects, interfaces, and structure to enhance electromagnetic and microwave absorption (MA) performance. However, accurately distinguishing the MA contributions of different scale factors and tuning the optimal combined effects remains a formidable challenge. This study employs a synergistic approach combining template protection etching and vacuum annealing to construct a controlled system of micrometer-sized cavities and amorphous carbon matrices in metal-organic framework (MOF) derivatives. The results demonstrate that the spatial effects introduced by the hollow structure enhance dielectric loss but significantly weaken impedance matching. By increasing the proportion of amorphous carbon, the balance between electromagnetic loss and impedance matching can be effectively maintained. Importantly, in a suitable graphitization environment, the presence of oxygen vacancies in amorphous carbon can induce significant polarization to compensate for the reduced conductivity loss due to the absence of sp2 carbon. Through the synergistic effects of morphology and composition, the samples exhibit a broader absorption bandwidth (6.28 GHz) and stronger reflection loss (−61.64 dB) compared to the original MOF. In conclusion, this study aims to elucidate the multiscale impacts of macroscopic micro-nano structure and microscopic defect engineering, providing valuable insights for future research in this field.
基金supported by the National Natural Science Foundation of China(Grant No.52235006 and 52025053)the Jilin Provincial Scientific and Technological Development Program(20220204119YY).
摘要Ceramic materials demonstrate great application potential in multiple fields such as aerospace and biomedical engineering due to their excellent mechanical properties,high-temperature resistance,and good biocompatibility,but their inherent brittleness and processing defects urgently need to be broken through.Inspired by the biological structures found in nature,the integration of biomimicry and additive manufacturing(AM)technologies offers a new pathway for the innovative design of high-performance ceramic materials.This article systematically reviews the fundamental principles and classifications of ceramic AM technology,focusing on six typical elements of biomimetic structural design:coaxial composite structures,surface reinforcement structures,layered composite structures,porous structures,composite multicomponent structures,and intelligent bionic structures.The review delves into their biomimetic principles,preparation strategies,performance advantages,and research progress.Research indicates that through multiscale topological design and functional integration,these structures can significantly enhance the mechanical properties and environmental adaptability of ceramics.Nevertheless,current technologies still face numerous challenges in balancing manufacturing precision and efficiency,controlling cracks and residual stresses caused by interface defects,ensuring long-term material stability under extreme environments,enhancing intelligent response capabilities,and guaranteeing process scalability and performance consistency in clinical applications.Future research should integrate multidisciplinary approaches to optimize structural design and dynamic response,transforming biomimetic ceramic materials from‘biological replication'to‘performance exceeding',thereby providing theoretical and technical support for the customized development of high-performance ceramic devices.
基金The National Key R&D Program for Developing Basic Sciences under contract No.2022YFC3104800the National Natural Science Foundation of China under contract Nos U2242214 and 92358302+2 种基金the Tai Shan Scholar Program under contract No.tstp20231237the Postdoctoral Applied Research Project sponsored by Qingdao Municipal Governmentthe fund supported by Laoshan Laboratory under contract No.LSKJ202300301。
摘要Ocean bottom pressure(OBP)reflects ocean dynamics,thermodynamics,and Earth’s gravity field,playing a key role in physical oceanography and in reducing aliasing errors in satellite gravimetry.Due to limited observations,highfrequency global OBP studies rely on numerical models,which inherently contain uncertainties.This study employs the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics(LASG/IAP)Climate System Ocean Model version 3.0(LICOM3.0)to simulate global OBP from 2002 to 2018,driven by two different atmospheric reanalysis datasets.Validation against in situ observations shows that LICOM3.0 effectively captures sub-seasonal OBP variability(1–30 d)at the available stations,which are located in the Pacific and along the Atlantic coast.Compared to another ocean model,LICOM3.0 reproduces similar OBP patterns for periods longer than 1 d and spatial scales greater than 500 km,demonstrating its capability for large-scale OBP analysis and assessing inter-model uncertainty.However,the model underestimates OBP amplitudes,and exhibits marked discrepancies at sub-daily periods,in marginal seas,and on spatial scales below 500 km with reference data.These issues are consistent across both experiments,indicating that model configuration contributes to the limitations.Potential sources of error are discussed to support future model improvements.Overall,LICOM3.0 can serve as an effective tool for oceanic scientific applications and for de-aliasing in satellite gravimetry applications.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.12072058 and U2341232).
摘要Voronoi structures are widely present in nature,and highly ordered Voronoi structures such as honeycomb structures have gained extensive recognition and in-depth research in the field of sound absorption structure design.However,Voronoi structures in biological tissues are not all highly ordered.Stochastic Voronoi structures are equally prevalent and exhibit excellent multifunctional properties.To further explore the acoustic value of stochastic Voronoi structures,this study proposes a Voronoi sound absorbing porous structure that features both structural stochasticity and performance robustness.First,a theoretical calculation model is established based on microperforated panel theory and Helmholtz resonance theory,enabling the rapid calculation of the structure’s sound absorption coefficient.Then,a systematic analysis is conducted on the effective conditions for absorption performance robustness from four dimensions:unit number,structural randomness,manufacturing errors,and boundary cutting.Results indicate that there exists a unit number threshold associated with absorption bandwidth in the Voronoi structure.When this threshold is exceeded,the structure can exhibit favorable sound absorption robustness against structural stochasticity,manufacturing errors,and boundary cutting.Experimental verification shows that under significant boundary changes,the structure still maintains an average sound absorption coefficient of approximately 0.8 within an absorption bandwidth of approximately 400 Hz.Its favorable low-frequency broadband sound absorption performance and robustness endow it with promising application prospects in engineering fields where cost control,environmental adaptability,and construction efficiency need to be balanced.
基金supported by the National Natural Science Foundation of China (32102600)the Central Publicinterest Scientific Institution Basal Research Fund, China (Y2023XK13, JBYW-AII-2024-28/40, and JBYWAII-2023-33/37/42)+1 种基金Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences (CAAS-ASTIP-2021-AII)the Wuhu Science and Technology Bureau Two Strong One Increase Project, China (2023ly12)。
摘要Detecting keypoints in dairy cows aims to locate and track the motion trajectories of the body's joints,which plays a crucial role in behavior analysis and lameness detection.However,real farming scenarios,characterized by occlusions and large variations in object scale may result in poor detection results.Therefore,we introduce the atrous spatial pyramid pooling(ASPP) module into the shallow layers network of ResNet101,designed to improve the multi-scale feature extraction capability of the model.The ASPP module enhances the robustness of recognition for different dimensional sizes and occluded keypoints using different dilatation rates in the parallel atrous convolutional layers to expand the model's receptive field.Furthermore,seven types of motion features,including tracking up,gait symmetry,step height balance,motion speed variability,head swing amplitude,head-neck slope and back curvature are extracted simultaneously by monitoring and tracking the motion trajectory of distinct keypoints.Several of these features represent innovative extraction models and attributes,first proposed in this study.Multiple models are trained and tested on datasets containing 2,385 frames for ablation experiments.The experiments show that,in comparison with the ResNet50,MobileNet_v2_1.0,and EfficientNet-b0backbone networks,the training error and test error of ResNet101 are reduced by 4.04-30.12 pixels and 3.81-28.14 pixels.Therefore,ResNet101 is used as the benchmark for subsequent model improvement by adding the ASPP module.The training error and test error of the ResNet101-ASPP network are reduced by 0.27 and 0.24 pixels,respectively,compared to the benchmark network.The prediction confidence improves by 1.65-2.50% at three different dairy cow object scales.In addition,the keypoints under different occlusion conditions improve considerably,especially for small-scale keypoints,demonstrating the capability of the ASPP module for multi-scale feature extraction.By analyzing the distribution of the seven features and health,mild lameness,and severe lameness in dairy cows,it is shown that all the different features play an important role in distinguishing between different levels of lameness.
基金supported by the Henan Province Key R&D Project under Grant 241111210400the Henan Provincial Science and Technology Research Project under Grants 252102211047,252102211062,252102211055 and 232102210069+2 种基金the Jiangsu Provincial Scheme Double Initiative Plan JSS-CBS20230474,the XJTLU RDF-21-02-008the Science and Technology Innovation Project of Zhengzhou University of Light Industry under Grant 23XNKJTD0205the Higher Education Teaching Reform Research and Practice Project of Henan Province under Grant 2024SJGLX0126。
摘要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.
基金supported,in part,by the National Nature Science Foundation of China under Grant 62272236,62376128in part,by the Natural Science Foundation of Jiangsu Province under Grant BK20201136,BK20191401.
摘要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.
基金supported by the National Science and Technology Major Project for New Oil and Gas Exploration and Development(Grant No.2025ZD1404102-02)the Joint Fund for Enterprise Innovation and Development of the National Natural Science Foundation of China(Grant No.U24B6001)the Sinopec Science and Technology Department Project(Grant No.P23221).
摘要Accurately characterizing the distribution and scale characteristics of fractures in subsurface media is a crucial step for quantitatively evaluating shale gas sweet spots and guiding reservoir fracturing stimulation.However,a single seismic attribute is often used to identify fracture features of a specifi c scale,making it diffi cult to achieve detailed characterization of fractures across multiple scales simultaneously.Multi-attribute fusion algorithms often focus on statistical correlations,lacking in-depth exploration of the spatial topological relationships and intrinsic physical connections among fractures of diff erent scales,resulting in reduced accuracy in complex structural areas.To address this challenge,we propose a multi-scale integrated fracture prediction method based on an improved deep embedded clustering(DEC)framework,using the marine shale reservoir of the Wufeng–Longmaxi Formation in southeastern Sichuan Basin as a case study.Specifically,(1)an improved DEC objective function integrating fracture topology constraints and cluster-balancing mechanisms is developed to enhance the model’s adaptability to complex geological structures;(2)an“expand–then–contract”stacked autoencoder architecture is designed to better capture nonlinear relationships among multi-attribute data and decouple multi-scale fracture features;and(3)an integrated workfl ow from multi-attribute optimization,intelligent fusion clustering to geological interpretation is established,enabling diff erentiated and high-precision characterization of multi-scale fractures.Furthermore,based on the geological characteristics of the study area,we systematically analyze the spatial mapping relationships of the autoencoder’s multi-layer features and elucidate their implicit geophysical signifi cance.This analysis reveals the intrinsic processes through which the proposed model performs fracture attribute optimization,noise separation,and multi-scale feature extraction.Finally,by integrating intelligent fault identifi cation,micro-fracture amplitude variation with azimuth(AVAZ)inversion,and conventional geometric attributes,high-precision spatial characterization of the fracture system is achieved,spanning from large-scale faults to micro-fractures.The prediction results show strong agreement with geological understanding.
基金funded by the National Natural Science Foundation of China,grant numbers 52374156 and 62476005。
摘要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.