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使用逐步CM曲线法检验测验单维性
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作者 井贤严 符华均 《考试研究》 2020年第3期26-31,共6页
单维性是传统项目反应理主化重要的结构假设。单维性检验是运用项目反应理论进行数据分析的重要环节。本文介绍一种基于Cronbach's α系数的简便的单维性检验方法,对其原理、操作过程和结果进行详细解释。在测验编制阶段,通过该方... 单维性是传统项目反应理主化重要的结构假设。单维性检验是运用项目反应理论进行数据分析的重要环节。本文介绍一种基于Cronbach's α系数的简便的单维性检验方法,对其原理、操作过程和结果进行详细解释。在测验编制阶段,通过该方法分析测验题目的结构、内容,能够对测验题目优化、修改提供有益参考。 展开更多
关键词 单维性检验 Cronbach'sα系数 逐步CM曲线
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Simulation of proppant transport at intersection of hydraulic fracture and natural fracture of wellbores using CFD-DEM 被引量:5
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作者 Siamak Akhshik Majid Rajabi 《Particuology》 SCIE EI CAS CSCD 2022年第4期112-124,共13页
Proppants transport is an advanced technique to improve the hydraulic fracture phenomenon,in order to promote the versatility of gas/oil reservoirs.A numerical simulation of proppants transport at both hydraulic fract... Proppants transport is an advanced technique to improve the hydraulic fracture phenomenon,in order to promote the versatility of gas/oil reservoirs.A numerical simulation of proppants transport at both hydraulic fracture(HF)and natural fracture(NF)intersection is performed to provide a better understand-ing of key factors which cause,or contribute to proppants transport in HF-NF intersection.Computational fluid dynamics(CFD)in association with discrete element method(DEM)is used to model the complex interactions between proppant particles,host fluid medium and fractured walls.The effect of non-spherical geometry of particles is considered in this model,using the multi-sphere method.All interaction forces between fluid flow and particles are considered in the computational model.Moreover,the inter-actions of particle-particle and particle-wall are taken into account via Hertz-Mindlin model.The results of the CFD-DEM simulations are compared to the experimental data.It is found that the CFD-DEM sim-ulation is capable of predicting proppant transport and deposition quality at intersections which are in agreement with experimental data.The results indicate that the HF-NF intersection type,fluid velocity and NF aperture affect the quality of blockage occurrence,presenting a new index,called the blockage coefficient which indicates the severity of the blockage. 展开更多
关键词 Hydraulic fracture process Proppants transport CFD-DEM method HF-NF intersection Blockage coffcient
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