搜索到38222篇“ UNIFORM“的相关文章
Non-uniform thermal behavior of single-layer spherical reticulated shell structures considering time-variant environmental factors: analysis and design
2024年
Contrary to conventional design methods that assume uniform and slow temperature changes tied to atmospheric conditions,single-layer spherical reticulated shells undergo significant non-uniform and time-variant temperature variations due to dynamic environmental coupling.These differences can affect structural performance and pose safety risks.Here,a systematic numerical method was developed and applied to simulate long-term temperature variations in such a structure under real environmental conditions,revealing its non-uniform distribution characteristics and time-variant regularity.A simplified design method for non-uniform thermal loads,accounting for time-variant environmental factors,was theoretically derived and validated through experiments and simulations.The maximum deviation and mean error rate between calculated and tested results were 6.1℃ and 3.7%,respectively.Calculated temperature fields aligned with simulated ones,with deviations under 6.0℃.Using the design method,non-uniform thermal effects of the structure are analyzed.Maximum member stress and nodal displacement under non-uniform thermal loads reached 119.3 MPa and 19.7 mm,representing increases of 167.5%and 169.9%,respectively,compared to uniform thermal loads.The impacts of healing construction time on non-uniform thermal effects were evaluated,resulting in construction recommendations.The methodologies and conclusions presented here can serve as valuable references for the thermal design,construction,and control of single-layer spherical reticulated shells or similar structures.
Wucheng XUXiaoqing ZHENGXuanhe ZHANGZhejie LAIYanbin SHEN
A Uniform or Regular Clothes?
2024年
What should students wearto school?Some say uniforms.Uniforms ca reduce bullying becauseeeveryone wears the same thing.Students can't tease others about their clothes.Also,students focus better in class when they wear uniforms.They aren't thinking about clothes.Getting ready for school is also easier.Students don't have to decide on their clothes.They just wear their uniform.
Ruth Devlin
关键词:EVERYONEWEARUNIFORM
面向通感一体化的非均匀感知信号设计
2024年
通感一体化被国际电信联盟ITU确定为6G的六大应用场景之一,而感知信号设计是通感一体化研究中的一个重要议题。传统的均匀感知信号设计具有时频资源开销大、信号设计灵活度差等问题,而非均匀感知信号设计能够解决上述问题。首先对三种非均匀信号设计方法的原理进行梳理和对比,给出非均匀信号设计在感知信号时频资源配置中的应用和链路自适应方法。然后基于vivo公司自研的通感一体化样机平台,对三种非均匀感知信号设计进行了初步的测试验证的性能对比。测试结果表明,非均匀感知信号在显著节约时频资源的情况下,能够取得较好的感知性能。
丁圣利李健之姜大洁陈保龙姚健秦飞
Comparing two IBM implementations for the simulation of uniform packed beds被引量:1
2024年
Nowadays,the design of fixed packed bed reactors still relies on empirical correlations,which,especially for small tube to particle diameter ratios,are mostly too inaccurate because of the presence of wall effects.Therefore,the simulation of fixed packed bed reactors plays an important role to predict and control the flow and process parameters in such,nowadays and in the future.Because of its straightforward applicability to non-uniform packings with particles of arbitrary shapes,the immersed boundary method(IBM)has advantages over other numerical methods and is used more and more frequently.This paper compares two approaches of IBMs for the simulation of fixed bed reactors with spherical shaped particles.The classic,smooth approach is compared to the straightforward to implement blocked-off method for velocity fields above the fixed bed for particle Reynolds numbers of 300 and 500.Results from experimental inline PIV-measurements of the reactor to be simulated serve as a basis for comparison.Very good agreement with the experiment is found for both simulation methodologies with higher resolutions,considering the more stable flow at a particle Reynolds number of 300.Differences in the different IBM approaches occurred for the more unsteady flow at a particle Reynolds number of 500.Compared to the blocked-off method,the smooth IBM reflects the formation of additional jets and recirculation zones better right above the bed,though increasing the fluid mesh resolution improves the accuracy of the blocked-off method.Overall,a more diffusive behaviour is found for the blocked-off simulations due to the stairstep representation,which is avoided by using interpolation stencils as in the smooth IBM.With higher mesh refinement in the blocked-off IBM this effect can be reduced,but this also increases the computational effort.
Christian GorgesMaximilian BrommerChristin VeltenSiegmar WirtzEnric Illana MahiquesViktor SchererKatharina ZahringerBerend van Wachem
Turán number of Berge linear forests in uniform hypergraphs
2024年
Let F be a graph and H be a hypergraph.We say that H contains a Berge-F If there exists a bijectionψ:E(F)→E(H)such that for Ve E E(F),e C(e),and the Turan number of Berge-F is defined to be the maximum number of edges in an r-uniform hypergraph of order n that is Berge-F-free,denoted by ex,(n,Berge-F).A linear forest is a graph whose connected components are all paths or isolated vertices.Let Ln,k be the family of all linear forests of n vertices with k edges.In this paper,Turan number of Berge-Ln,in an r-uniform hypergraph is studied.When r≥k+1 and 3≤r≤l[]=1,we determine 2 the exact value of ex,(n,Berge-Ln,)respectively.When K-1≤r≤k,we 2 determine the upper bound of ex,(n,Berge-Ln,).
Liying KANGJiawei HUANGYisai XUEZhiwei WU
刚度变化对行星轮系均载特性的影响分析
2024年
建立直齿圆柱齿轮行星齿轮传动系统的三维模型,并利用动力学仿真软件构建虚拟样机模型;通过动力学分析,验证了虚拟样机仿真模型的准确性和可行性。研究表明,传动系统中各零部件的支承刚度对均载特性均有明显影响,行星轮的支承刚度变化对均载特性的影响最为敏感;传动系统均载特性对太阳轮柔性支承刚度变化并不敏感,但对行星轮柔性支承刚度变化敏感性较强,均载系数有明显变化;轮齿啮合刚度变化对传动系统均载特性的影响具有独立性,同时减小内、外啮合刚度比单独降低啮合刚度的均载效果更为明显。
李凯阳李爱国林锐怡师陆冰颜世铛刘忠明
关键词:行星轮系支承刚度啮合刚度均载系数均载特性
Effect of non-uniform swelling on coal multiphysics during gas injection: The triangle approach
2024年
In current dual porosity/permeability models,there exists a fundamental assumption that the adsorption-induced swelling is distributed uniformly within the representative elementary volume (REV),irrespective of its internal structures and transient processes.However,both internal structures and transient processes can lead to the non-uniform swelling.In this study,we hypothesize that the non-uniform swelling is responsible for why coal permeability in experimental measurements is not only controlled by the effective stress but also is affected by the adsorption-induced swelling.We propose a concept of the swelling triangle composed of swelling paths to characterize the evolution of the non-uniform swelling and serve as a core link in coupled multiphysics.A swelling path is determined by a dimensionless volumetric ratio and a dimensionless swelling ratio.Different swelling paths have the same start and end point,and each swelling path represents a unique swelling case.The swelling path as the diagonal of the triangle represents the case of the uniform swelling while that as the two perpendicular boundaries represents the case of the localized swelling.The paths of all intermediate cases populate inside the triangle.The corresponding relations between the swelling path and the response of coal multiphysics are established by a non-uniform swelling coefficient.We define this method as the triangle approach and corresponding models as swelling path-based ones.The proposed concept and models are verified against a long-term experimental measurement of permeability and strains under constant effective stress.Our results demonstrate that during gas injection,coal multiphysics responses have a close dependence on the swelling path,and that in both future experiments and field predictions,this dependence must be considered.
Yifan HuangJishan LiuYaoyao ZhaoDerek ElsworthYee-Kwong Leong
关键词:HETEROGENEITY
An improved non-uniform fast Fourier transform method for radio imaging of coronal mass ejections
2024年
Radioheliographs can obtain solar images at high temporal and spatial resolution,with a high dynamic range.These are among the most important instruments for studying solar radio bursts,understanding solar eruption events,and conducting space weather forecasting.This study aims to explore the effective use of radioheliographs for solar observations,specifically for imaging coronal mass ejections(CME),to track their evolution and provide space weather warnings.We have developed an imaging simulation program based on the principle of aperture synthesis imaging,covering the entire data processing flow from antenna configuration to dirty map generation.For grid processing,we propose an improved non-uniform fast Fourier transform(NUFFT)method to provide superior image quality.Using simulated imaging of radio coronal mass ejections,we provide practical recommendations for the performance of radioheliographs.This study provides important support for the validation and calibration of radioheliograph data processing,and is expected to profoundly enhance our understanding of solar activities.
Weidan ZhangBing WangZhao WuShuwang ChangYao ChenFabao Yan
关键词:GRIDDINGIMAGING
Frost deformation and microstructure evolution of porous rock under uniform and unidirectional freeze-thaw conditions
2024年
The frost deterioration and deformation of porous rock are commonly investigated under uniform freeze-thaw(FT)conditions.However,the unidirectional FT condition,which is also prevalent in engineering practice,has received limited attention.Therefore,a comparative study on frost deformation and microstructure evolution of porous rock under both uniform and unidirectional FT conditions was performed.Firstly,frost deformation experiments of rock were conducted under cyclic uniform and unidirectional FT action,respectively.Results illustrate that frost deformation of saturated rock exhibits isotropic characteristics under uniform FT cycles,while it shows anisotropic characteristics under unidirectional FT condition with both the frost heaving strain and residual strain along FT direction much higher than those perpendicular to FT direction.Moreover,the peak value and residual value of cumulative frost strain vary as logarithmic functions with cycle number under both uniform and unidirectional FT conditions.Subsequently,the microstructure evolution of rock suffered cyclic uniform and unidirectional FT action were measured.Under uniform FT cycles,newly generated pores uniformly distribute in rock and pore structure of rock remains isotropic in micro scale,and thus the frost deformation shows isotropic characteristics in macro scale.Under unidirectional FT cycles,micro-cracks or pore belts generate with their orientation nearly perpendicular to the FT direction,and rock structure gradually becomes anisotropic in micro scale,resulting in the anisotropic characteristics of frost deformation in macro scale.
LV ZhitaoLIU JintaoWAN LingLIU Weiping
Global Phase Portraits of Uniform Isochronous Centers System of Degree Six with Polynomial Commutator
2024年
This paper studies the global phase portraits of uniform isochronous centers system of degree six with polynomial commutator.Such systems have the form x=-y+xf(x,y),y=x+yf(x,y),where f(x,y)=a_(1)x+a_(2)xy+a_(3)xy^(2)+a_(4)xy^(3)+a_(5)xy^(4)=xσ(y),and any zero of 1+a_(1)y+a_(2)y^(2)+a_(3)y^(3)+a_(4)y^(4)+a_(5)y^(5),y=y is an invariant straight line.At last,all global phase portraits are drawn on the Poincare disk.
Li-na GUOAi-yong CHENShuai-feng ZHAO

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