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Quantitative evaluation of coal fracability based on 3D CT reconstruction and fractal characteristics
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作者 Fanhui Zeng Weixin Yang +3 位作者 Jianchun Guo Ran Zhang Yu Zhang Zhangxing Chen 《Natural Gas Industry B》 2026年第1期60-76,共17页
Fracability is a critical indicator for evaluating the exploration and development potential of coalbed methane reservoirs and assessing the effectiveness of hydraulic fracturing stimulation operations.Its core functi... Fracability is a critical indicator for evaluating the exploration and development potential of coalbed methane reservoirs and assessing the effectiveness of hydraulic fracturing stimulation operations.Its core function is to characterize the complexity of the induced fracture network and the resulting effective stimulated volume.In this study,we quantified fracture area and geometric complexity using true triaxial fracturing experiments and computed tomography three-dimensional(3D)reconstruction technology,combined with the box-counting method to calculate the 3D fractal dimension of the fracture surfaces.The results revealed that the total fracture surface area per unit volume of the stimulated reservoir effectively characterized reservoir fracability;specifically,both a larger total fracture surface area and a higher fractal dimension corresponded to better reservoir fracability.Fracture complexity was enhanced by a decrease in the horizontal principal stress difference or an increase in the injection rate.Under optimal conditions of a 3 MPa stress difference and an injection rate of 60 mL/min,fracability improved by 27.6%.Furthermore,liquid carbon dioxide(CO_(2))improved fracability by 50.7%compared to using water as the fracturing fluid,a result attributed to its low viscosity and strong diffusion capacity,which activated a greater number of natural fractures.A fracability evaluation model integrating brittleness,fracture toughness,and dimensionless net pressure was developed using regression analysis,which demonstrated high reliability with a strong determination coefficient(R^(2))of 0.9019.This study clarifies the logical relationships among fracture area,complexity,and fractal dimension,providing a novel method for evaluating the fracability of coal reservoirs. 展开更多
关键词 COAL Fracability evaluation 3D reconstruction Fractal dimension Fracture area
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Deterioration and Pore Structure Evolution of GO Modified Polymer Cement Mortar under Salt-freeze-thaw Coupling Effects
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作者 ZHAO Xinyuan WEI Zhiqiang +3 位作者 QIAO Hongxia LI Shaofei CAO Hui XI Lingling 《Journal of Wuhan University of Technology(Materials Science)》 2026年第1期234-246,共13页
To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with g... To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively. 展开更多
关键词 graphene oxide polymer cement mortar pore structure fractal dimension
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Cooperative Metaheuristics with Dynamic Dimension Reduction for High-Dimensional Optimization Problems
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作者 Junxiang Li Zhipeng Dong +2 位作者 Ben Han Jianqiao Chen Xinxin Zhang 《Computers, Materials & Continua》 2026年第1期1484-1502,共19页
Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when ta... Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when tackling high-dimensional optimization challenges.To effectively address these challenges,this study introduces cooperative metaheuristics integrating dynamic dimension reduction(DR).Building upon particle swarm optimization(PSO)and differential evolution(DE),the proposed cooperative methods C-PSO and C-DE are developed.In the proposed methods,the modified principal components analysis(PCA)is utilized to reduce the dimension of design variables,thereby decreasing computational costs.The dynamic DR strategy implements periodic execution of modified PCA after a fixed number of iterations,resulting in the important dimensions being dynamically identified.Compared with the static one,the dynamic DR strategy can achieve precise identification of important dimensions,thereby enabling accelerated convergence toward optimal solutions.Furthermore,the influence of cumulative contribution rate thresholds on optimization problems with different dimensions is investigated.Metaheuristic algorithms(PSO,DE)and cooperative metaheuristics(C-PSO,C-DE)are examined by 15 benchmark functions and two engineering design problems(speed reducer and composite pressure vessel).Comparative results demonstrate that the cooperative methods achieve significantly superior performance compared to standard methods in both solution accuracy and computational efficiency.Compared to standard metaheuristic algorithms,cooperative metaheuristics achieve a reduction in computational cost of at least 40%.The cooperative metaheuristics can be effectively used to tackle both high-dimensional unconstrained and constrained optimization problems. 展开更多
关键词 Dimension reduction modified principal components analysis high-dimensional optimization problems cooperative metaheuristics metaheuristic algorithms
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Impacts of X-ray energy and beam size on CD-SAXS measurement precision
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作者 Xu-Yang Qin Bing Guo +7 位作者 Nan Pan Xin-Hao Gao Shu-Min Yang Chun-Xia Hong Ying Wang Xiu-Hong Li Chun-Ming Yang Feng-Gang Bian 《Nuclear Science and Techniques》 2026年第4期65-78,共14页
With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this ... With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this study,the effects of X-ray beam size and photon energy on the accuracy of critical dimension measurements were investigated.Critical dimensions measured using beams with different spot sizes showed different deviations from the expected values.Beam sizes that were either too large or too small did not improve confidence intervals.As the incident energy increased,the X-ray transmission rate increased,while the scattering cross section decreased,resulting in a gradual decrease in the signal-to-noise ratio of the diffraction peaks,which reduced the accuracy of the CD-SAXS measurements.An optimal accuracy was obtained at 12 keV with a smaller beam size.Using an effective trapezoid model,the results yielded an average pitch of 100.4±0.2 nm,width of 49.8±0.2 nm,height of 130.0±0.2 nm,and a sidewall angle below 1.1°±0.1°.These results provide crucial guidance for the future development of CD-SAXS laboratories and the construction of X-ray machines as well as robust support for research in related fields. 展开更多
关键词 Critical dimension small-angle X-ray scattering Nonlinear fitting Beam size X-ray energy Chip
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THE VARIATIONAL PRINCIPLE FOR A BS DIMENSION OF SUBSETS FOR NON-AUTONOMOUS DYNAMICAL SYSTEMS
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作者 Zhongxuan YANG Xiaojun HUANG 《Acta Mathematica Scientia》 2026年第1期311-329,共19页
In this manuscript,we consider a non-autonomous dynamical system.Using the Carathéodory structure,we define a BS dimension on an arbitrary subset and obtain a Bowen’s equation that illustrates the relation of th... In this manuscript,we consider a non-autonomous dynamical system.Using the Carathéodory structure,we define a BS dimension on an arbitrary subset and obtain a Bowen’s equation that illustrates the relation of the BS dimension to the Pesin-Pitskel topological pressure given by Nazarian[24].Moreover,we establish a variational principle and an inverse variational principle for the BS dimension of non-autonomous dynamical systems.Finally,we also get an analogue of Billingsley’s theorem for the BS dimension of non-autonomous dynamical systems. 展开更多
关键词 non-autonomous dynamical systems BS dimension Bowen’s equation variational principle
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GROWTH RATE OF DIGITS IN A GAUSS-LIKE IFS
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作者 Saisai SHI Bo TAN Qinglong ZHOU 《Acta Mathematica Scientia》 2026年第1期293-310,共18页
LetΨ={ψn}n≥1 be an iterated function system(IFS)on[0,1]with attractor J.Associated with each x∈J,there is a sequence{ωn(x)}n≥1 consisting of integers,called the digit sequence of x,such that■((1))We revisit the... LetΨ={ψn}n≥1 be an iterated function system(IFS)on[0,1]with attractor J.Associated with each x∈J,there is a sequence{ωn(x)}n≥1 consisting of integers,called the digit sequence of x,such that■((1))We revisit the Borel-Bernstein theorem in a d-decaying Gauss-like IFS,and completely characterize the metrical properties of the set■whereΦ:ℕ→ℝis a positive function. 展开更多
关键词 Gauss-like iterated function system Diophantine approximation Hausdorff dimension
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Effect of dominant fractures on triaxial behavior of 3D-printed rock analogs with internal fracture networks
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作者 Lishuai Jiang Pimao Li +3 位作者 Xin He Yang Zhao Quansen Wu Ye Zhao 《Journal of Rock Mechanics and Geotechnical Engineering》 2026年第2期1390-1412,共23页
Internal structural defects in engineering rock masses vary in size,exhibit complex shapes,and are unevenly distributed.Dominant fractures within a rock mass often play a critical to its mechanical behavior,directly a... Internal structural defects in engineering rock masses vary in size,exhibit complex shapes,and are unevenly distributed.Dominant fractures within a rock mass often play a critical to its mechanical behavior,directly affecting the macromechanical properties and failure modes.These fractures affect the instability and failure of the surrounding rock,significantlyimpacting the overall stability of engineering structures.Herein,sand-powder three-dimensional(3D)printing technology was used to prepare rock-like specimens with internal fracture networks.Triaxial compression testing,post-failure fracture mapping,and fractal dimension analysis of the fracture surfaces were conducted to investigate the effects of dominant fracture angles on the strength and deformation of rocks with internal fracture networks under triaxial stress.The results indicate that the dominant fracture angle has a pronounced effect on the mechanical behavior of rock.With increasing angle,both compressive strength and elastic modulus exhibit an initial decline followed by an increase.Moreover,higher confiningpressure significantlyimproves the compressive strength of fractured rock.This enhancement weakens as the confiningpressure further increases.Moreover,with increasing confiningpressure,the differences between the maximum and minimum values of elastic moduli and lateral strain ratios in fractured rock gradually decrease.Thus,the impact of the dominant fracture angle on rock mass deformation decreases with increasing confiningpressure.This research elucidates the effects of dominant fracture angles on the mechanical and failure properties of complex fractured rock masses and the influenceof the confiningpressure on these relationships.It provides valuable theoretical insights and practical guidance for stability analyses in engineering rock masses. 展开更多
关键词 Sand powder three-dimensional(3D) printing Internal fracture networks Triaxial compression Rock mechanics Fractal dimension
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CO_(2)nanobubble-enhanced cement-fly ash backfill:Optimizing aggregate gradation and microstructure
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作者 Xiaoxiao Cao Haoyan Lyu +4 位作者 Yanlong Chen Jiangyu Wu Hideki Shimada Takashi Sasaoka Akihiro Hamanaka 《International Journal of Minerals,Metallurgy and Materials》 2026年第1期129-140,共12页
Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and intro... Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and introducing CO_(2)nanobubble technology to improve the performance of cement-fly ash-based backfill materials(CFB).The properties including fluidity,setting time,uniaxial compressive strength,elastic modulus,porosity,microstructure and CO_(2)storage performance were systematically studied through methods such as fluidity evaluation,time test,uniaxial compression test,mercury intrusion porosimetry(MIP),scanning electron microscopy-energy dispersive spectroscopy analysis(SEM-EDS),and thermogravimetric-differential thermogravimetric analysis(TG-DTG).The experimental results show that the density and strength of the material are significantly improved under the synergistic effect of fractal dimension and CO_(2)nanobubbles.When the fractal dimension reaches 2.65,the mass ratio of coarse and fine aggregates reaches the optimal balance,and the structural density is greatly improved at the same time.At this time,the uniaxial compressive strength and elastic modulus reach their peak values,with increases of up to 13.46%and 27.47%,respectively.CO_(2)nanobubbles enhance the material properties by promoting hydration reaction and carbonization.At the microscopic level,CO_(2)nanobubble water promotes the formation of C-S-H(hydrated calcium silicate),C-A-S-H(hydrated calcium aluminium silicate)gel and CaCO_(3),which is the main way to enhance the performance.Thermogravimetric studies have shown that when the fractal dimension is 2.65,the dehydration of hydration products and the decarbonization process of CaCO_(3)are most obvious,and CO_(2)nanobubble water promotes the carbonization reaction,making it surpass the natural state.The CO_(2)sequestration quality of cement-fly ash-based materials treated with CO_(2)nanobubble water at different fractal dimensions increased by 12.4wt%to 99.8wt%.The results not only provide scientific insights for the design and implementation of low-carbon filling materials,but also provide a solid theoretical basis for strengthening green mining practices and promoting sustainable resource utilization. 展开更多
关键词 cement-fly ash-based backfill CO_(2)nanobubble fractal dimension macro and micro performance carbon sequestration
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Fractal Geometry-based Porosity Analysis of Cementitious Composite Material Using Wollastonite Under Freeze-thaw Condition 被引量:1
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作者 Aziza Kuldasheva HUANG Bin +2 位作者 Kholjigit Kuldashev LI Beixing Bakhtiyor Saidmuratov 《Journal of Wuhan University of Technology(Materials Science)》 2025年第3期769-779,共11页
Low porosity is very significant for cementitious composite materials(CCM)under freeze-thaw conditions.To reduce the porosity of CCM,we used wollastonite mineral fibers as a partial replacement for cement and aggregat... Low porosity is very significant for cementitious composite materials(CCM)under freeze-thaw conditions.To reduce the porosity of CCM,we used wollastonite mineral fibers as a partial replacement for cement and aggregate.The five combinations,in which 10%,32%,and 48%Wollastonite were added,were made for scanning using both scanning electron microscopy(SEM)and computed tomography scan technology(CT).Then,the 2D SEM pictures and the 3D pore distribution curves are obtained before and after the freezing and thawing processes,where the micro-pores in the CCM materials are shown.The fractal dimension is used to quantify the topography image in two dimensions,as well as the pore distribution in three dimensions.This method allows for the determination of both surface porosity and volume porosity,both of which show an increase in response to an escalation of freeze-thaw cycles.It is also found that the micro-damage in the concrete is of self-similarity,and in the context of the fractal dimension,the pore evolution can be quantitatively characterized across different sizes,ranging from local to global levels,before and after freezing and thawing. 展开更多
关键词 WOLLASTONITE recycled-enriched aggregates fractal dimension freeze-thaw cycle CCM SEM CT
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A Deep Learning-Aided Method for Precise Identification of Microporosity:A Case Study from the Marine Hydrocarbon Reservoirs in the South China Sea 被引量:1
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作者 GUO Dingrui GOLSANAMI Naser +10 位作者 ZHANG Zhi GYIMAH Emmanuel BAKHSHI Elham AHMAD Qazi Adnan BEHNIA Mahmoud SABERALI Behzad YAN Weichao DONG Huaimin SHENDY Saeid Ahmadizadeh JAYASURIYA Madusanka N FERNANDO Shanilka G 《Journal of Ocean University of China》 2025年第6期1450-1468,共19页
The accurate identification of microporosity is crucial for the characterization of hydrocarbon reservoir permeability and production.Scanning electron microscopy(SEM)is among the limited number of methods available t... The accurate identification of microporosity is crucial for the characterization of hydrocarbon reservoir permeability and production.Scanning electron microscopy(SEM)is among the limited number of methods available to directly observe the microscopic structure of the hydrocarbon reservoir rocks.Nevertheless,precise segmentation of microscopic pores at different depths in SEM images remains an unsolved challenge,known as the‘depth-related resolution loss'problem.Therefore,in this study,a 3D reconstruction technique for regions of interest(ROI)was developed for in-depth pixel analysis and differentiation among various depths of SEM images.The processed SEM images,together with the processing outcomes of this technique,were used as the input database to train a stochastic depth with multi-channel residual pathways(SdstMcrp)deep learning model programmed in Python to develop a tool for segmenting the microscopic pore spaces in SEM images obtained from the Beibuwan Basin.The more accurate segmentation helped to detect an average of 1.2 times more microporosity in SEM images,accounting for about 1.6 times more pixels and 1.2 times more pore surface area.Finally,the impact of the accurate segmentation on the calculation of permeability,a significant reservoir production property,was investigated using fractal geometry models and sensitivity analysis.The results showed that the obtained permeability values would vary by a factor of 6,which represents a considerable difference.These findings demonstrate that the proposed models can effectively identify features across a wide range of grayscale values in SEM images. 展开更多
关键词 SEM depth of field resolution loss PERMEABILITY deep learning fractal dimension
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Influences of maximum principal stress direction and cross-section shape on tunnel stability 被引量:1
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作者 Xuefeng Si Zilong Zhang +4 位作者 Xibing Li Guansheng Yi Yong Luo Lihai Tan Kaifeng Han 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第4期2159-2180,共22页
To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with... To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with rectangular,circular,and D-shaped holes.Asθincreases from 0°to 60°in the rectangular hole,the left failure location shifts from the left corner to the left sidewall,the left corner,and then the floor,while the right failure location shifts from the right corner to the right sidewall,right roof corner,and then the roof.Furthermore,the initial failure vertical stress first decreases and then increases.In comparison,the failure severity in the rectangular hole decreases for variousθvalues as 30°>45°>60°>0°.With increasingθ,the fractal dimension(D)of rock slices first increases and then decreases.For the rectangular and D-shaped holes,whenθ=0°,30°,and 90°,D for the rectangular hole is less than that of the D-shaped hole.Whenθ=45°and 60°,D for the rectangular hole is greater than that of the D-shaped hole.Theoretical analysis indicates that the stress concentration at the rectangular and D-shaped corners is greater than the other areas.The failure location rotates with the rotation ofθ,and the failure occurs on the side with a high concentration of compressive stress,while the side with the tensile and compressive stresses remains relatively stable.Therefore,the fundamental reason for the rotation of failure location is the rotation of stress concentration,and the external influencing factor is the rotation ofθ. 展开更多
关键词 Maximum principal stress direction Cross-section shape True-triaxial experiment Failure characteristics Fractal dimension Theoretical analysis
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Morphological damage and strength deterioration of red sandstone under freeze-thaw cycles 被引量:1
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作者 Jincheng Wang Deshan Cui +2 位作者 Qiong Chen Juxiang Chen Mingjie Dai 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第2期671-687,共17页
Insight into the growth of internal microstructure and surface morphology is critical for understanding the robustness of red sandstone artifacts in frigid environments.Since freeze–thaw(F-T)cycles can exacerbate the... Insight into the growth of internal microstructure and surface morphology is critical for understanding the robustness of red sandstone artifacts in frigid environments.Since freeze–thaw(F-T)cycles can exacerbate the surface deterioration of water-bearing sandstone,a series of investigation on fresh and weathered water-bearing sandstone samples with different F-T cycle numbers(i.e.0–100)is performed in this study,including three-dimensional(3D)laser scanning,scanning electron microscope(SEM)and computed tomography(CT)scanning tests,thermal property tests,Brazilian tests,and multi-field numerical simulations.Our results demonstrate that with increasing F-T cycles,the surface fractal dimension and specific surface area of red sandstone samples increase,and the pore size distribution inside rocks shifts from ultrananopores(10–100 nm)to micro-pores(0.1–100μm)and ultramicropores(100μm+).Spatially,the pores generated by the F-T cycles are more prominent near the surfaces of rock samples.Numerical simulation indicates that the uneven pore distribution leads to surface degradation.After 100 F-T cycles,the intergranular(IG)cement of the samples cracks,and the IG fractures are widened;eventually,due to the structural integrity weakening,the tensile strength is drastically reduced by over half.The thermal properties of the water-saturated sandstone can be improved during the F-T cycles,and a strong coefficient of determination of 0.98 exists between the fractal dimensions of sandstone surface and the tensile strength.When assessing the mechanical properties of stone artifacts under F-T cycles,the morphological damage of red sandstone should first be investigated when in situ sampling is inappropriate. 展开更多
关键词 Freezing-thawing cycles Red sandstone Pore structure Surface fractal dimension Computed tomography(CT)reconstruction
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Feature pyramid attention network for audio-visual scene classification 被引量:1
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作者 Liguang Zhou Yuhongze Zhou +3 位作者 Xiaonan Qi Junjie Hu Tin Lun Lam Yangsheng Xu 《CAAI Transactions on Intelligence Technology》 2025年第2期359-374,共16页
Audio-visual scene classification(AVSC)poses a formidable challenge owing to the intricate spatial-temporal relationships exhibited by audio-visual signals,coupled with the complex spatial patterns of objects and text... Audio-visual scene classification(AVSC)poses a formidable challenge owing to the intricate spatial-temporal relationships exhibited by audio-visual signals,coupled with the complex spatial patterns of objects and textures found in visual images.The focus of recent studies has predominantly revolved around extracting features from diverse neural network structures,inadvertently neglecting the acquisition of semantically meaningful regions and crucial components within audio-visual data.The authors present a feature pyramid attention network(FPANet)for audio-visual scene understanding,which extracts semantically significant characteristics from audio-visual data.The authors’approach builds multi-scale hierarchical features of sound spectrograms and visual images using a feature pyramid representation and localises the semantically relevant regions with a feature pyramid attention module(FPAM).A dimension alignment(DA)strategy is employed to align feature maps from multiple layers,a pyramid spatial attention(PSA)to spatially locate essential regions,and a pyramid channel attention(PCA)to pinpoint significant temporal frames.Experiments on visual scene classification(VSC),audio scene classification(ASC),and AVSC tasks demonstrate that FPANet achieves performance on par with state-of-the-art(SOTA)approaches,with a 95.9 F1-score on the ADVANCE dataset and a relative improvement of 28.8%.Visualisation results show that FPANet can prioritise semantically meaningful areas in audio-visual signals. 展开更多
关键词 dimension alignment feature pyramid attention network pyramid channel attention pyramid spatial attention semantic relevant regions
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Research status and prospects of the fractal analysis of metal material surfaces and interfaces
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作者 Qinjin Dai Xuefeng Liu +2 位作者 Xin Ma Shaojie Tian Qinghe Cui 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS 2025年第1期20-38,共19页
As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal... As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions.Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces.However,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials.From the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear surfaces.The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized.Starting from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed.It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future. 展开更多
关键词 metal material surfaces and interfaces fractal analysis fractal dimension HOMOGENEITY
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Managing Multidimensional International World With Spatial Grasp Model 被引量:1
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作者 Peter Simon Sapaty 《International Relations and Diplomacy》 2025年第5期257-269,共13页
“Multidimensional international world”refers to understanding the world through multiple dimensions beyond traditional economic or political measures,fostering cross-cultural collaboration,and creating systems that ... “Multidimensional international world”refers to understanding the world through multiple dimensions beyond traditional economic or political measures,fostering cross-cultural collaboration,and creating systems that balance global integration with local needs.This also includes management of global business operations across diverse cultures in a multipolar international landscape.The paper briefs the developed and already tested in numerous applications high-level Spatial Grasp Model and Technology(SGT),which can help investigate and manage complex systems with a holistic spatial approach effectively covering various physical and virtual dimensions,their interrelations,and integration as a whole.Different areas will be investigated with examples of practical solutions in them and their combinations in a high-level Spatial Grasp Language(SGL),the key element of SGT.This allows for the creation and distributed management of very large spatial networks with different orientation which can be self-spreading,self-analyzing,self-modifying,and self-recovering in complex terrestrial and celestial environments,and also organize dynamic multi-networking solutions supporting global evolution and integrity. 展开更多
关键词 multidimensional world Spatial Grasp Technology Spatial Grasp Language distributed network operations dimensions investigation and management collective spatial solutions global integrity
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Hierarchical Event-Triggered Predictive Control for Cross-Domain Unmanned Systems With Mixed Constraints 被引量:1
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作者 Ming-Feng Ge Yi-Fan Li +3 位作者 Chen-Bin Wu Zhi-Wei Liu Yan Jia Si-Sheng Liu 《IEEE/CAA Journal of Automatica Sinica》 2025年第9期1938-1940,共3页
Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmann... Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs).We assume that each agent suffers from by the mixed constraints on its velocity,control input and Euler angle.Solving the MDFT problem implies that 1)The virtual state of each USV is determined in the earth coordinate by expanding its 2D work space to the 3D space. 展开更多
关键词 expanding its d work space mixed constraints unmanned aerial vehicles interconnected agentsnamelyunmanned aerial vehicles uavs multi dimension formation tracking hierarchical event triggered predictive control unmanned surface vehicles usvs we virtual state
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On the Relative Growth Rate of the Digits in Sylvester Continued Fraction Expansions
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作者 LV Meiying RAO Guilin 《应用数学》 北大核心 2025年第2期468-476,共9页
For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial... For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function. 展开更多
关键词 Sylvester continued fraction expansions Growth rate Hausdorff dimension
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Structural analysis of rock fracture networks for subsurface investigation purposes in Morocco
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作者 Abderrahim Ayad Tarik Tagma 《Geodesy and Geodynamics》 2025年第6期727-737,共11页
In addition to being among the major tiggers behind frequent earthquakes,fractures can allow surface water to infiltrate the permeable rocks,entering both shallow and deep aquifers.Occasionally,water penetrates to gre... In addition to being among the major tiggers behind frequent earthquakes,fractures can allow surface water to infiltrate the permeable rocks,entering both shallow and deep aquifers.Occasionally,water penetrates to great depths,heats up,and becomes geothermal water.Fractures similarly allow hydrothermal fluids to dissolve their chemical elements and form a mineral deposit.Given these important roles of fractures,this paper aims to map faults and fractures across the entire Moroccan territory in the form of lineaments extracted from remotely sensed images,and then analyze their spatial distribution using the fractal dimension(FD)approach,and then generate a fractal map of the entire Morocco as a guide for subsurface investigation purposes.It was found that the areas with high fractal dimension(FD˃1),considered potential groundwater recharge areas,essentially the northern Anti Atlas,the southwestern High Atlas,and the Meseta,present spatial conformity with several known mineral deposits,geothermal areas,and the epicenters of many historical earthquakes.This conformity can be a key element in expecting other unexplored mineral deposits,aquifers,or geothermal regions,as well as predicting the areas that may bear earthquake hazards in areas with high FD across the entire Moroccan territory. 展开更多
关键词 LINEAMENTS FRACTURES GROUNDWATER Geothermy EARTHQUAKES Fractal dimension
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Strength of parrot fight feathers is a function of positionon the wing
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作者 Denis Charles Deeming Connor J.Hutchings +1 位作者 Fern G.Seaward Adrian M.Goodman 《Current Zoology》 2025年第2期212-222,共11页
Powered fight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures.Many basic aspects of feather functionality are unknown,which hampers our understanding of wing function in birds... Powered fight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures.Many basic aspects of feather functionality are unknown,which hampers our understanding of wing function in birds.This study measured the dimensions of primary and secondaryfight feathers of 19 species of parrots.The maximum force the feathers could withstand from below was also measured to mimic the pressuresexperienced during a downstroke.The analysis tested whether:(1)feather dimensions differed along the wing and among secondary and primary remiges;(2)the force that feathers could withstand varied among the remiges;and(3)there would be isometric relationships with bodymass for feather characteristics.The results show that body mass signifcantly affected vane width,rachis thickness,maximum force,and ultimate bending moment,but the relationship for feather length only approached signifcance.Many of the proximal secondary feathers showedsignifcantly lower values relative to the frst primary,whereas for distal primaries the values were greater.There were isometric relationships forforce measurements of primary and secondary feathers with body mass,but there was positive allometry for feather lengths and vane widths.The forces feathers can withstand vary along the wing may be a proxy for the aerodynamic properties of the feathers in situ.Broader taxonomicstudies that explore these topics are required for other species representing a range of different orders.A better understanding of the functionality of feathers will improve our understanding of how avian fight works particularly considering the variety in fight style and wing shape in birds. 展开更多
关键词 bending moment dimensions FEATHER force primary SECONDARY
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50 Practical Ways to Alter the Relative Efficiencies of Behaviors
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作者 Steve Ward Teresa Grimes 《Psychology Research》 2025年第2期37-53,共17页
Behavior analysts have long recognized the need to increase at least one behavior when attempting to decrease another and usually focus primarily upon increasing a wide variety of behaviors(White&Haring,1980).But ... Behavior analysts have long recognized the need to increase at least one behavior when attempting to decrease another and usually focus primarily upon increasing a wide variety of behaviors(White&Haring,1980).But the strengthening of any behavior relative to another is not necessarily simple and records of empirically supported treatment options can be interpreted in an over-simplified manner.The current paper attempts to connect various treatment options across behaviors through a common principle-levels of one behavior will tend to increase and levels of another will tend to decrease when the first behavior is made more efficient than the second.The primary objective of the current paper is to articulate a wide variety of variable dimensions available to behavior analysts,teachers,and other professionals responsible for behavior change.In complex environments,many factors are beyond our control and many treatment options are non-viable.The greater the variety of treatment options available,the“larger the analyst’s toolbox”,the greater the chance that viable treatments will be found and that ineffective strategies can be effectively modified before being set aside.One recurring theme is that various forms of response blocking can and should be minimized and replaced with strategies that make more desirable behavior more efficient than less desirable behavior,leading learners to“choose”more desirable behavior.An additional objective of the paper is to reframe the debate about whether it is appropriate to use extinction or punishment,wherein those strategies are frequently interpreted in absolute terms,in relation to decreasing undesirable behaviors,and inevitably result in negative side effects.A more nuanced discussion about extinction and punishment considers the extent to which parametric applications of either might be appropriate to make a less desirable behavior less efficient than a more desirable behavior and includes the potential impact upon increasing desirable behaviors. 展开更多
关键词 Matching Law efficiency consequences perspectives CONSTRUCTIVISM variable dimensions
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