搜索到8843篇“ NON-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
Pressure transient characteristics of non-uniform conductivity fractured wells in viscoelasticity polymer flooding based on oil-water two-phase flow
2024年
Polymer flooding in fractured wells has been extensively applied in oilfields to enhance oil recovery.In contrast to water,polymer solution exhibits non-Newtonian and nonlinear behavior such as effects of shear thinning and shear thickening,polymer convection,diffusion,adsorption retention,inaccessible pore volume and reduced effective permeability.Meanwhile,the flux density and fracture conductivity along the hydraulic fracture are generally non-uniform due to the effects of pressure distribution,formation damage,and proppant breakage.In this paper,we present an oil-water two-phase flow model that captures these complex non-Newtonian and nonlinear behavior,and non-uniform fracture characteristics in fractured polymer flooding.The hydraulic fracture is firstly divided into two parts:high-conductivity fracture near the wellbore and low-conductivity fracture in the far-wellbore section.A hybrid grid system,including perpendicular bisection(PEBI)and Cartesian grid,is applied to discrete the partial differential flow equations,and the local grid refinement method is applied in the near-wellbore region to accurately calculate the pressure distribution and shear rate of polymer solution.The combination of polymer behavior characterizations and numerical flow simulations are applied,resulting in the calculation for the distribution of water saturation,polymer concentration and reservoir pressure.Compared with the polymer flooding well with uniform fracture conductivity,this non-uniform fracture conductivity model exhibits the larger pressure difference,and the shorter bilinear flow period due to the decrease of fracture flow ability in the far-wellbore section.The field case of the fall-off test demonstrates that the proposed method characterizes fracture characteristics more accurately,and yields fracture half-lengths that better match engineering reality,enabling a quantitative segmented characterization of the near-wellbore section with high fracture conductivity and the far-wellbore section with low fracture conduct
Yang WangJia ZhangShi-Long YangZe-Xuan XuShi-Qing Cheng
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
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
Modeling of Rectangular Microchannel Heat Sink with Non-Uniform Channels and Multi-Objective Optimization
2024年
Rectangular microchannel heat sinks(MCHS)are widely used to cool high-heat-flux electronic devices.However,previous studies focused mainly on MCHS with uniform channels(UCs).This study considers a microchannel heat sink with non-uniform channels(NUCs).A mathematical model is developed based on energy equations and the Darcy flow principle.Explicit expressions for total thermal resistance and coolant pressure drop are derived using the thermoelectric analogy.Experiments and numerical simulations are performed to verify the mathematical model.As non-uniformity increases,total coolant pressure drop decreases but at the cost of higher thermal resistance.The overall performance of NUCs is better than that of UCs because of their lower ratio of pumping power to cooling power.Heat transfer performance of NUCs changes little for more than 120 channels and depends mainly on channel arrangement.A multi-objective optimization is conducted to minimize the thermal resistance and pumping power of an NUC.An optimal NUC saves 64%pumping power compared with a conventional UC for the total thermal resistance of 0.1℃/W,indicating that the use of non-uniform channels could be very helpful to reduce the flow resistance of MCHS.
SHANG XueshuoWANG YixinLI QingwenWANG RuiCUI ZhengSHAO Wei
Study of the pressure transient behavior of directional wells considering the effect of non-uniform flux distribution
2024年
During the production,the fluid in the vicinity of the directional well enters the wellbore with different rates,leading to non-uniform flux distribution along the directional well.However,in all existing studies,it is oversimplified to a uniform flux distribution,which can result in inaccurate results for field applications.Therefore,this paper proposes a semi-analytical model of a directional well based on the assumption of non-uniform flux distribution.Specifically,the direction well is discretized into a carefully chosen series of linear sources,such that the complex well trajectory can be captured and the nonuniform flux distribution along the wellbore can be considered to model the three-dimensional flow behavior.By using the finite difference method,we can obtain the numerical solutions of the transient flow within the wellbore.With the aid of Green's function method,we can obtain the analytical solutions of the transient flow from the matrix to the wellbore.The complete flow behavior of a directional well is perfectly represented by coupling the above two types of transient flow.Subsequently,on the basis of the proposed model,we conduct a comprehensive analysis of the pressure transient behavior of a directional well.The computation results show that the flux variation along the direction well has a significant effect on pressure responses.In addition,the directional well in an infinite reservoir may exhibit the following flow regimes:wellbore afterflow,transition flow,inclined radial flow,elliptical flow,horizontal linear flow,and horizontal radial flow.The horizontal linear flow can be observed only if the formation thickness is much smaller than the well length.Furthermore,a dip region that appears on the pressure derivative curve indicates the three-dimensional flow behavior near the wellbore.
Yan-Zhong LiangBai-Lu TengWan-Jing Luo
高温强余旋非均匀来流条件模拟方法研究
2024年
针对新一代一体化加力燃烧室进口高温强余旋非均匀进气特点,设计了一种可用于模拟一体化加力燃烧室真实进气条件的高温强余旋非均匀进口流场发生装置,该装置能够模拟真实的一体化加力燃烧室进口来流条件。同时开展了耦合进口马赫数、温度和余旋角度的不均匀流场数值模拟研究,评估了非均匀来流生成装置设计、测量方法与评价指标的有效性,并通过试验结果验证了数值模拟的准确性。结果表明:数值计算所得余旋角误差在壁面附近约为±2°,这是由于数值计算低估了壁面的耗散作用,而在中心区域则在优于±2°;同样在马赫数不均匀模拟中,在主流区域误差在10%以内;此外在对于温度不均匀性的模拟中,数值仿真表现出了较大的误差,这是因为数值计算中未考虑壁面向外界的传热过程。综合来看,本文所提出的高温强余旋非均匀生成装置可生成用于模拟下一代一体化加力燃烧室进口所面临的真实复杂不均匀进口流场条件,所采用的数值模拟方法可以较为准确地揭示流场非均匀特性。
刘云鹏张举星邸东颜应文
Investigation of non-uniform leading-edge tubercles in compressor cascade:Based on multi-objective optimization and data mining
2024年
Corner stall receives noticeable attention in the aeroengine field as an important phenomenon in highly-load compressors.Non-uniform leading-edge tubercles,as an effective method to delay stall,are introduced into the compressor.In this paper,the shape of leading-edge tubercles was controlled by a third-order Fourier function.To judge corner stall,a more precise stall indicator for compressor cascade with flow control methods was defined.Besides,the total kinetic energy of the secondary flow at large incidence was adopted as a parameter for stall evaluation to save computing resources.The results of multiobjective optimization reveal that the loss coefficient exhibited negligible variation at design incidence,while the total kinetic energy of secondary flow showed a significant reduction at large incidence,resulting in a substantial increase in stall incidence.In the optimal profiling cases,the stall incidencewas delayed from 7.9°to 11.6°.The major purpose of the research is to provide proper design guidelines for nonuniformleading-edge tubercles and uncover the flow controlmechanisms of leading-edge profiling.Hence,the geometric features that meet different optimization objectives were extracted through geometric analysis near the Pareto Front and through Self-OrganizingMap(SOM)dataminingmethods in the optimization database.Besides,flow field analysis reveals the flow control mechanism of leading-edge tubercles.The convex-concave-convex structure at the 0%-70%blade height region can form two branches of leading-edge vortex pairs that are opposite in the rotation direction to the passage vortex.The two branches of leading-edge vortex pairs mixed with the leading-edge separation vortex to form two stronger mixed vortices,which can effectively suppress the development of passage vortex and delay stall incidence.
Jiezhong DONGWuli CHUHaoguang ZHANGBo LUOTianyuan JIZiyun ZHANG
一种利用深度学习的非均匀无记忆信源恢复方法
2024年
针对非均匀无记忆信源这一特殊自然冗余信源的接收端符号恢复问题,基于全连接神经网络模型,设计一种将接收信号的信噪比和无记忆信源的符号分布随接收数据一起作为模型输入的神经网络译码器架构。并提出一种基于此神经网络的迭代译码算法,实现在发送符号分布未知情况下的自然冗余译码。仿真结果表明,利用自然冗余可以提升接收端的符号检测性能,即使在信源分布未知的情况下也能获得理论上最优的性能。
王振玉菅春晓刘成城赵安军王彦生王亚杰

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