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对随机投影算法的离群数据挖掘技术研究 被引量:3
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作者 李桥 周莹莲 +1 位作者 黄胜 马翔 《计算机工程与应用》 CSCD 2013年第24期122-129,共8页
d维点集离群数据挖掘技术是目前数据挖掘领域的研究热点之一。当前基于距离或最近邻概念进行离群数据挖掘时,在高维数据情况下的挖掘效果不佳,鉴于此,将基于角度的离群因子应用到高维离群数据挖掘中,提出一种新的基于随机投影算法的离... d维点集离群数据挖掘技术是目前数据挖掘领域的研究热点之一。当前基于距离或最近邻概念进行离群数据挖掘时,在高维数据情况下的挖掘效果不佳,鉴于此,将基于角度的离群因子应用到高维离群数据挖掘中,提出一种新的基于随机投影算法的离群数据挖掘方案,它只需要用接近线性时间的方法就能预测所有数据点的基于角度的离群因子。该方法可以用于并行环境进行并行加速。对近似质量进行了理论分析,以保证算法的可靠性。合成和真实数据集实验结果表明,对超高维数据集,该方法效率高、可伸缩性强。 展开更多
关键词 离群数据挖掘 角度 随机投影算法 接近线性时间 可靠性 效率
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基于灰色关联投影随机森林算法的水平井压后产能预测及压裂参数优化 被引量:6
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作者 潘元 王永辉 +2 位作者 车明光 廖锐全 郑恒 《西安石油大学学报(自然科学版)》 北大核心 2021年第5期71-76,共6页
基于数据挖潜建立了压裂油井产量预测与合理压裂参数优选的灰色关联投影随机森林算法,采用加权的灰色关联投影方法筛选出数据集;采用网格搜索交叉验证方法对森林模型参数进行优化;在此基础上训练随机森林回归模型进行产量预测,结合响应... 基于数据挖潜建立了压裂油井产量预测与合理压裂参数优选的灰色关联投影随机森林算法,采用加权的灰色关联投影方法筛选出数据集;采用网格搜索交叉验证方法对森林模型参数进行优化;在此基础上训练随机森林回归模型进行产量预测,结合响应面分析方法对压裂参数进行优化。产量预测实例表明该算法的决定系数0.9189高于随机森林算法、梯度提升决策树算法;三口井日产油实际值与预测值之间的误差为9.6%、1.2%、1.1%。结合新疆玛湖油田实际储层对M1井进行压裂优化:总压裂液量21000 m^(3)、裂缝簇数34条、总砂量1181.86 m^(3)为最佳压裂参数,此时日产油为44.356 m^(3)。 展开更多
关键词 压裂水平井产量预测 压裂参数优化 灰色投影随机森林算法 致密储层
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Polarization Projection for 3D Geometry-Based Stochastic Channel Model
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作者 PANG Lihua ZHANG Yang +5 位作者 GONG Fengkui WANG Anyi XIAO Liyuan LIANG Xiao WANG Qiaofeng LI Jiandong 《China Communications》 SCIE CSCD 2015年第10期52-63,共12页
Comprehensive radiation characteristics of polarized antenna are crucial in creating practical channel coefficients for next generation wireless communication system designs.Being currently supported within3 D geometr... Comprehensive radiation characteristics of polarized antenna are crucial in creating practical channel coefficients for next generation wireless communication system designs.Being currently supported within3 D geometry-based stochastic channel models(GSCM),field patterns are technically obtained by chamber measurement(or by its best fitting).However,in some channel related performance analysis scenarios,design insight can be crystallized better by starting the derivations with theoretical co-polarization and cross-polarization components.Specifically,these two components are mathematically linked with field patterns through the proposed polarization projection algorithm.In this manuscript,we focus on revealing the transformation criterion of polarization states between the antenna plane and the propagation plane.In practice,it makes retrieving the field patterns by electromagnetic computation possible.Meanwhile,the impact imposed by distinct antenna orientations is geometrically illustrated and consequently incorporated into the proposed algorithm.This will further facilitate flexible performance evaluation of related radio transmission technologies.Our conclusions are verified by the closed-form expression of the dipole field pattern(via an analytical approach) and by chamber measurement results.Moreover,we find that its 2D degenerative case is aligned with the definitions in 3^(rd) generation partnership project(3GPP)technical report 25.996.The most obvious benefit of the proposed algorithm is to significantly reduce the cost on generating channel coefficients in GSCM simulation. 展开更多
关键词 polarization 3D geometry-based stochastic channel model antenna orientation radiation characteristics dipole chamber measurement channel simulation
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