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Viscoelasticity of mixed polyacrylamide solution
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作者 徐丽娜 《Journal of Central South University》 SCIE EI CAS 2008年第S1期443-446,共4页
The viscoelastic behavior of polyacrylamide solution is crucial for its application in various industries.The mixed polyacrylamide solution was prepared by mixing polyacrylamide with different relative molecular masse... The viscoelastic behavior of polyacrylamide solution is crucial for its application in various industries.The mixed polyacrylamide solution was prepared by mixing polyacrylamide with different relative molecular masses according to the defined mass fraction.The viscosity and elasticity of mixed polyacrylamide solution were separately tested with RS150 rheometer and capillary breakup extensional rheometer and compared with those of the single polyacrylamide solution which is directly provided by manufacturer without any mixing.The results indicate that the mixed and single polyacrylamide solutions have the same shear viscosity and intrinsic viscosity.However,some mixed polyacrylamide solutions have higher elasticity than single polyacrylamide solution.The flow resistance of mixed polyacrylamide with higher elasticity is also greater than that of single polyacrylamide solution in porous medium.This paper presents an effective method of mixing polyacrylamides with different relative molecular masses,which can enhance the elasticity of polyacrylamide solution and flowing resistance through porous medium. 展开更多
关键词 POLYACRYLAMIDE VISCOSITY elasticity flow RESISTANCE
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E-Cervix imaging displaying cervical elasticity characteristics of healthy adult nulliparous women at different age groups and different menstrual cycle stages
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作者 XU Yunyan WANG Mingli +1 位作者 LYU Xiaoli LI Xuelei 《中国医学影像技术》 CSCD 北大核心 2024年第8期1208-1211,共4页
Objective To observe the cervical elasticity of healthy adult nulliparous women at different age groups and different stages of menstrual cycle with E-Cervix imaging technology.Methods A total of 218 healthy adult nul... Objective To observe the cervical elasticity of healthy adult nulliparous women at different age groups and different stages of menstrual cycle with E-Cervix imaging technology.Methods A total of 218 healthy adult nulliparous women who underwent transvaginal ultrasound examination for routine physical examination were retrospectively enrolled,including 103 in follicular phase,78 in ovulation phase and 37 in luteal phase.Cervical canal length(CL)and E-Cervix elasticity parameters were compared among different age groups and different stages of menstrual cycle,including elasticity contrast index(ECI),hardness ratio(HR),cervical internal and external orifice strain values(IOS and EOS)and IOS/EOS ratio.Results No significant difference of CL nor cervical elasticity parameters was detected among healthy adult nulliparous women at different age groups(all P>0.05).There were significant differences of ECI,HR and IOS among different menstrual cycle stages(all P<0.05),among which women in follicular phase had higher ECI and IOS but lower HR than those in luteal phase(all P<0.05).Conclusion No significant difference of cervical elasticity existed among healthy adult nulliparous women at different age groups.Meanwhile,cervical elasticity of healthy adult nulliparous women changed during menstrual cycle,in follicular phase had higher ECI and IOS but lower HR than in luteal phase. 展开更多
关键词 cervix uteri MENSTRUATION ULTRASONOGRAPHY elasticity imaging techniques
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Effects of static aeroelasticity on composite wing characteristics under different flight attitudes
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作者 霍世慧 袁喆 +1 位作者 王富生 岳珠峰 《Journal of Central South University》 SCIE EI CAS 2013年第2期312-317,共6页
Composite wing static aeroelasticity was analyzed through a loosely coupled method and the effects on composite wing characteristics under different flight attitudes were presented. Structural analysis and aerodynamic... Composite wing static aeroelasticity was analyzed through a loosely coupled method and the effects on composite wing characteristics under different flight attitudes were presented. Structural analysis and aerodynamic analysis were carried out through finite element method (FEM) software NASTRAN and computational fluid dynamics (CFD) software FLUENT, respectively. Correlative data transfer and mesh regenerate procedure were applied to couple the results of computational structure dynamics (CSD) and CFD. After static aeroelasticity analysis under different flight attitudes, it can be seen that lift increases with the increase of flight speed and the incremental value enlarges gradually in both rigid and elastic wings. Lift presents a linear increment relationship with the increase of attack angle when the flight speed is 0.4Ma or 0.6Ma, but nonlinear increment in elastic wing when flight speed is 0.8Ma. On the effect of aeroelasticity, the maximum of deformation increases with the increase of flight speed and attack angle, and the incremental value decreases with the increase of flight speed while uniform with different attack angles. The results provide a reference for engineering applications. 展开更多
关键词 static aeroelasticity elastic deformation aerodynamic characteristics structural characteristics flight attitudes
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Combined effects of local curvature and elasticity of an isothermal wall for jet impingement cooling under magnetic field effects 被引量:2
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作者 SELİMEFENDİGİL Fatih ÇOĞAN Mehmet ÖZTOP Hakan F. 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第11期3534-3544,共11页
The aim of this study is to examine the effects of local curvature and elastic wall effects of an isothermal hot wall for the purpose of jet impingement cooling performance.Finite element method was used with ALE.Diff... The aim of this study is to examine the effects of local curvature and elastic wall effects of an isothermal hot wall for the purpose of jet impingement cooling performance.Finite element method was used with ALE.Different important parametric effects such as Re number(between 100 and 700),Ha number(between 0 and 20),elasticity(between 104 and 109),curvature of the surface(elliptic,radius ratio between 1 and 0.25) and nanoparticle volume fraction(between 0 and 0.05) on the cooling performance were investigated numerically.The results showed that the average Nu number enhances for higher Hartmann number,higher values of elastic modulus of partly flexible wall and higher nanoparticle volume fraction.When the magnetic field is imposed at the highest strength,there is an increase of3.85% in the average Nu for the curved elastic wall whereas it is 89.22% for the hot part above it,which is due to the vortex suppression effects.Nanoparticle inclusion in the base fluid improves the heat transfer rate by about 27.6% in the absence of magnetic field whereas it is 20.5% under the effects of magnetic field at Ha=20.Curvature effects become important for higher Re numbers and at Re=700,there is 14.11% variation in the average Nu between the cases with the lowest and highest radius ratio.The elastic wall effects on the heat transfer are reduced with the increased curvature of the bottom wall. 展开更多
关键词 jet impingement nanoparticles elastic wall MHD CFD curved wall
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Effects of Water Stress on Tissue Elasticity in Nine Tree Species
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作者 Li JiyueForest Resources College,Beijing Forestry University 《北京林业大学学报》 CAS CSCD 北大核心 1992年第S2期25-32,共8页
The experiments were carried out under the conditions of controlled soil water potential in a greenhouse. The effects of water stress on tissue elasticity were studied in 1 - 3 year-old seedlings Pinus tabulaeformis, ... The experiments were carried out under the conditions of controlled soil water potential in a greenhouse. The effects of water stress on tissue elasticity were studied in 1 - 3 year-old seedlings Pinus tabulaeformis, Platycladus orientalis, Quercus variabilis, Acer truncatum , Robinia psendoacacia, Fraxinus americana , Amorpha fruticosa, Hip-pophea rahmnoides and Cotinus coggygria ,using the pressure-volume method. Tissue elasticity was characterized using graphs of the modulus of elasticity plotted as a function of turgor pressure and maximum values of the elastic modulus. Changes in tissue elasticity may be an important characteristic allowing low water potentials to be reached and maintained without the development of detrimental water stress. The results show that tissue e-lasticity in needle-leaved tree species is higher than in broad-leaved tree species,but the modulus of elasticity of the tree species tend to increase following development of water stress. Increases in elastic modulus 展开更多
关键词 WATER stress WATER potential TURGOR elastic MODULUS pressure-volume
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Elasticity under pressure and thermal property of Mg2La from first-principles calculations
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作者 牛晓峰 黄志伟 +2 位作者 胡磊 王涵 王宝健 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第8期1713-1719,共7页
The elastic properties, thermodynamic and electronic structures of Mg_2La were investigated by using first-principles. The calculated results show that pressure affects the elastic constants of C_(11) more than that o... The elastic properties, thermodynamic and electronic structures of Mg_2La were investigated by using first-principles. The calculated results show that pressure affects the elastic constants of C_(11) more than that of C_(12) and C_(44). Specifically, higher pressure leads to greater bulk modulus(B), shear modulus(G), and elastic modulus(E). We predict B/G and anisotropy factor A based on the calculated elastic constants. The Debye temperature also increases with increasing pressure. Based on the quasi-harmonic Debye model, we examined the thermodynamic properties. These properties include the normalized volume(V/V_0), bulk modulus(B), heat capacity(C_v), thermal expansion coefficient(α), and Debye temperature(■). Finally, the electronic structures associated with the density of states(DOS) and Mulliken population are analyzed. 展开更多
关键词 first-principles elastic properties thermodynamics properties electronic structure
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超声弹性成像技术在肌肉骨骼系统的应用进展 被引量:11
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作者 张佳玮 毕胜 《中国康复医学杂志》 CAS CSCD 北大核心 2017年第7期851-854,共4页
超声成像技术在肌肉骨骼系统的应用已久,传统的灰阶超声(B-mode ultrasonography)以其无创、实时等特点常成为首选;随着技术进步,超声弹性成像(sonoelastography,SEL;ultrasound elastography,UE)作为一种新型超声技术逐渐崭露头角。
关键词 肌肉骨骼系统 超声弹性成像 灰阶超声 超声成像技术 组织弹性 超声探头 足底筋膜 定量超声 肌腱病 elasticity
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An improved model of the Pasternak foundation beam umbrella arch considering the generalized shear force
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作者 CHEN Lei JIA Chao-jun +3 位作者 LEI Ming-feng HE Yan-chun SHI Cheng-hua LI Ao 《Journal of Central South University》 2025年第4期1503-1519,共17页
The existing analytical models for umbrella arch method(UAM)based on elastic foundation beams often overlook the influence of the surrounding soil beyond the beam edges on the shear stresses acting on the beam.Consequ... The existing analytical models for umbrella arch method(UAM)based on elastic foundation beams often overlook the influence of the surrounding soil beyond the beam edges on the shear stresses acting on the beam.Consequently,such models fail to adequately reflect the continuity characteristics of soil deformation.Leveraging the Pasternak foundation-Euler beam model,this study considers the generalized shear force on the beam to account for the influence of soil outside the beam ends on the shear stress.An analytical model for the deformation and internal forces of finite-length beams subjected to arbitrary loads is derived based on the initial parameter method under various conditions.The mechanical model of the elastic foundation beam for advanced umbrella arch under typical tunnel excavation cycles is established,yielding analytical solutions for the longitudinal response of the umbrella arch.The reliability of the analytical model is verified with the existing test data.The improved model addresses anomalies in existing models,such as abnormal upward deformation in the loosened segment and maximum deflection occurring within the soil mass.Additionally,dimensionless characteristic parameters reflecting the relative stiffness between the umbrella arch structure and the foundation soil are proposed.Results indicate that the magnitude of soil characteristic parameters significantly influences the deformation and internal forces of the umbrella arch.Within common ranges of soil values,the maximum deformation and internal forces of the umbrella arch under semi-logarithmic coordinates exhibit nearly linear decay with decreasing soil characteristic parameters.The impact of tunnel excavation height on the stress of unsupported sections of the umbrella arch is minor,but it is more significant for umbrella arch buried within the soil mass.Conversely,the influence of tunnel excavation advance on the umbrella arch is opposite. 展开更多
关键词 elastic foundation beam Pasternak foundation generalized shear umbrella arch analytical model
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Microstructure and mechanical properties of novel SiC-TiC/Al-Mg-Sc-Zr composites prepared by selective laser melting
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作者 LU Ren-yi MA Guo-nan +4 位作者 BAI Guan-shun ZHAO Wen-tian ZHANG Hui-hua ZHAO Shu-ming ZHUANG Xin-peng 《Journal of Central South University》 2025年第5期1641-1659,共19页
In order to obtain high-density dual-scale ceramic particles(8.5 wt.%SiC+1.5 wt.%TiC)reinforced Al-Mg Sc-Zr composites with uniform microstructure,50 nm TiC and 7μm SiC particles were pre-dispersed into 15−53μm alum... In order to obtain high-density dual-scale ceramic particles(8.5 wt.%SiC+1.5 wt.%TiC)reinforced Al-Mg Sc-Zr composites with uniform microstructure,50 nm TiC and 7μm SiC particles were pre-dispersed into 15−53μm aluminum alloy powders by low-speed ball milling and mechanical mixing technology,respectively.Then,the effects of laser energy density,power and scanning rate on the density of the composites were investigated based on selective laser melting(SLM)technology.The effect of micron-sized SiC and nano-sized TiC particles on solidification structure,mechanical properties and fracture behaviors of the composites was revealed and analyzed in detail.Interfacial reaction and phase variations in the composites with varying reinforced particles were emphatically considered.Results showed that SiC-TiC particles could significantly improve forming quality and density of the SLMed composites,and the optimal relative density was up to 100%.In the process of laser melting,a strong chemical reaction occurs between SiC and aluminum matrix,and micron-scale acicular Al_(4)SiC_(4) bands were formed in situ.There was no interfacial reaction between TiC particles and aluminum matrix.TiC/Al semi-coherent interface had good bonding strength.Pinning effect of TiC particles in grain boundaries could prevent the equiaxial crystals from growing and transforming into columnar crystals,resulting in grain refinement.The optimal ultimate tensile strength(UTS),yield strength(YS),elongation(EL)and elastic modulus of the SiC-TiC/Al-Mg-Sc-Zr composite were~394 MPa,~262 MPa,~8.2%and~86 GPa,respectively.The fracture behavior of the composites included ductile fracture of Al matrix and brittle cleavage fracture of Al_(4)SiC_(4) phases.A large number of cross-distributed acicular Al_(4)SiC_(4) bands were the main factors leading to premature failure and fracture of SiC-TiC/Al-Mg-Sc-Zr composites. 展开更多
关键词 selective laser melting interface structure aluminum matrix composite mechanical properties elastic modulus
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Mechanical response and impact tendency index correction of gangue-coal combined structure
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作者 WEN Zhi-jie XU Chang-long +2 位作者 GONG Feng-qiang ZUO Yu-jun SONG Zhen-qi 《Journal of Central South University》 2025年第6期2288-2306,共19页
To investigate the mechanical response during failure and the impact tendency characteristics of gangue-coal combined structure,uniaxial compression tests were conducted on nine groups of combined structures,each with... To investigate the mechanical response during failure and the impact tendency characteristics of gangue-coal combined structure,uniaxial compression tests were conducted on nine groups of combined structures,each with varying gangue thicknesses and positions.The response patterns of compressive strength,elastic modulus,pre-peak accumulated energy,elastic energy index,and impact energy index were systematically analyzed.Furthermore,a new index for evaluating the impact tendency of gangue-containing coal was proposed,and its effectiveness was verified.The findings are as follows:(1)As the gangue thickness increases,both the compressive strength and the pre-peak energy of the combined structure decrease,whereas the elastic modulus increases accordingly.When the gangue is located in the lower middle position,the combined structure exhibits the lowest compressive strength and elastic modulus but the highest pre peak energy.(2)As the gangue shifts toward the middle position of the combined structure,the failure mode gradually transitions from comple te“crushing”failure to an incomplete“point-type”failure.As gangue thickness further increases,the failure region evolves from overall failure to localized failure,with the degree of failure shifting from complete to incomplete.The K_(crc)value corresponding to“crushing”complete failure is higher and has a stronger impact tendency compared to“point-type”incomplete failure.(3)The proposed comprehensive impact instability evaluation index K_(crc)for the gangue-coal combined structure has shown a significant positive correlation with compressive strength(R_(c))and impact energy index(K_(E)),further verifyi ng its rationality in comprehensively assessing the impact tendency of gangue-containing coal bodies.Applying this index to the evaluation of gangue-containing coal seams provides a more accurate reflection of their impact tendency compared with the residual energy index,which has a wide range of potential applications and practical significance. 展开更多
关键词 gangue-coal combined structure mechanical response peak elastic energy density difference impact tendency comprehensive impact instability index
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基于lasso和elastic net的宽度学习系统网络结构稀疏方法 被引量:11
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作者 褚菲 苏嘉铭 +3 位作者 梁涛 陈俊龙 王雪松 马小平 《控制理论与应用》 EI CAS CSCD 北大核心 2020年第12期2543-2550,共8页
本文提出了一种基于lasso和elastic net的宽度学习系统(BLS)网络结构稀疏方法,将标准BLS目标函数中的L2范数分别替换为lasso和elastic net,利用这两种正则化技术来约束网络输出权重,衡量每个网络节点输出权重对预测的影响程度,将多余的... 本文提出了一种基于lasso和elastic net的宽度学习系统(BLS)网络结构稀疏方法,将标准BLS目标函数中的L2范数分别替换为lasso和elastic net,利用这两种正则化技术来约束网络输出权重,衡量每个网络节点输出权重对预测的影响程度,将多余的节点进行剔除,提高了网络结构的稀疏性.通过对一些回归数据集进行实验,可以看到本文提出的方法在不损失预测精度的前提下,同时简化了网络结构. 展开更多
关键词 宽度学习系统 网络结构 lasso elastic net
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基于SEA的机器人仿肌弹性驱动关节研究 被引量:12
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作者 何福本 梁延德 +1 位作者 孙捷夫 郭超 《中国机械工程》 EI CAS CSCD 北大核心 2014年第7期900-905,共6页
为了实现机器人的拟人运动,提高其对外部环境的适应性,基于串联弹性驱动器(SEA)驱动形式提出一种仿肌弹性驱动的机器人转动关节,以实现机器人在受迫振动或受冲击下的柔顺自调整运动。该关节机构参考人体肌肉-肌腱组织的Hill-type模型,... 为了实现机器人的拟人运动,提高其对外部环境的适应性,基于串联弹性驱动器(SEA)驱动形式提出一种仿肌弹性驱动的机器人转动关节,以实现机器人在受迫振动或受冲击下的柔顺自调整运动。该关节机构参考人体肌肉-肌腱组织的Hill-type模型,采用具有对抗形式的主动弹性驱动和被动弹性牵制的设计方案,模拟肌肉收缩运动和功能,产生牵拉力以驱动机器人的关节。通过对该弹性驱动关节进行建模分析,得到其动力学描述方程,结合多次仿真测试中获得的系统运动特性曲线,在掌握其运动规律的基础上完成了其动力学性能评估。此外,针对关节机构具有的强弹性、低刚度特点,提出一种基于虚拟刚度补偿的控制方法,并应用在具有仿肌弹性驱动关节的二自由度机器臂上,实验结果表明其可行、有效。 展开更多
关键词 仿生机构 机器人 串联弹性驱动器 肌肉-肌腱 刚度控制 series elastic actuator(SEA)
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基于云计算及大数据技术的电力搜索引擎技术研究 被引量:28
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作者 楼凤丹 裴旭斌 +1 位作者 王志强 纪德良 《电网与清洁能源》 北大核心 2016年第12期86-92,99,共8页
电力营销经过多年的信息化发展,企业内部已经建立大量异构型应用系统,产生了大量分散的结构化、半结构化、非结构化数据。基于云计算及大数据技术的电力"求索"搜索引擎技术,构建集中式数据中心全文检索的索引,实现对大规模不... 电力营销经过多年的信息化发展,企业内部已经建立大量异构型应用系统,产生了大量分散的结构化、半结构化、非结构化数据。基于云计算及大数据技术的电力"求索"搜索引擎技术,构建集中式数据中心全文检索的索引,实现对大规模不同业务功能和业务数据的统一检索,满足用户从大量异构业务系统和海量数据中进行快速检索的要求。电力"求索"搜索引擎技术基于开源的Elastic Search,利用分布式索引、分布式检索、分布式缓存技术,实现分布式全文检索平台,提供对大规模索引数据的高效管理与快速、灵活的访问能力。通过搜索引擎技术,综合利用文本挖掘、自然语言处理、信息检索等领域的技术,进一步提高全文检索的查准率、查全率。该技术的应用,可以满足大规模不同业务数据的统一检索的需求;并同时满足大规模数据检索请求的快速响应要求。 展开更多
关键词 ELASTIC SEARCH 电力 云计算 大数据 分布式全文检索 单点登录
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光谱分析中Elastic Net变量选择与降维方法 被引量:4
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作者 赵安新 汤晓君 +2 位作者 宋娅 张钟华 刘君华 《红外与激光工程》 EI CSCD 北大核心 2014年第6期1977-1981,共5页
在利用红外光谱进行多组分混合气体定量分析建模中,须根据各目标气体成分的光谱特点进行光谱维数降维和特征变量选择。以甲烷、乙烷、丙烷、异丁烷、正丁烷、异戊烷和正戊烷等7种气体为分析目标,采用最小绝对收缩和选择算子(LASSO)与弹... 在利用红外光谱进行多组分混合气体定量分析建模中,须根据各目标气体成分的光谱特点进行光谱维数降维和特征变量选择。以甲烷、乙烷、丙烷、异丁烷、正丁烷、异戊烷和正戊烷等7种气体为分析目标,采用最小绝对收缩和选择算子(LASSO)与弹性网络(ElasticNet)方法进行目标气体数据预处理。针对LASSO和Elastic Net方法参数优化选择的问题,采用均方误差和预测偏差最小两个准则进行参数的优化选取。对4cm-1的实测光谱数据,采用LASSO和ElasticNet方法分别在0.0019和0.0021均方误差条件下使得维度从2542维分别降为2维和3维,LASSO的交叉灵敏度最大和最小为10.2718%和1.4205%,ElasticNet分别为5.4945%和0.7493%。结果表明:Elastic Net在用于光谱定量分析的数据预处理中具有一定的优势,为准确建立定量分析模型奠定了基础。 展开更多
关键词 气体红外光谱定量分析 正则化算法 特征波长选择 LASSO ELASTIC NET
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网络口碑对网络销售农产品的作用机理——基于“天猫”某品牌茶叶销售的实证研究 被引量:11
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作者 王克喜 崔准 《农林经济管理学报》 CSSCI 2014年第2期186-191,共6页
以网络广泛销售的农产品———茶叶为研究对象,在收集并处理网上顾客评论数据的基础上,探究网络口碑对这类农产品线上销售的作用机理。在控制相关内生性因素的前提下,建立农产品网络口碑弹性模型EK,并对面板数据进行分位数回归分析。结... 以网络广泛销售的农产品———茶叶为研究对象,在收集并处理网上顾客评论数据的基础上,探究网络口碑对这类农产品线上销售的作用机理。在控制相关内生性因素的前提下,建立农产品网络口碑弹性模型EK,并对面板数据进行分位数回归分析。结果表明,在农产品网络销售中,网络口碑数量、评分及产品价格对农产品的销售都有显著影响。在不同销量分位数下,各变量对销量的影响不同:口碑数量的弹性趋势相对平稳;口碑评分弹性则呈现出不规则的U型趋势;价格的弹性值均为负,整体走势趋于缓慢上升。 展开更多
关键词 网络口碑 农产品网络销售 分位数回归 elastic model of electronic WORD-OF-MOUTH ( EK)
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Adaptive Elastic Net方法在Logistic回归模型中的应用(英文) 被引量:4
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作者 李春红 黄登香 戴洪帅 《工程数学学报》 CSCD 北大核心 2015年第5期759-771,共13页
本文将adaptive Elastic Net方法应用于Logistic回归模型,研究并证明其具有Oracle性质,并利用数值模拟及实际例子将其与Lasso、adaptive Lasso、Elastic Net方法的估计结果进行比较,从结果可以看出,adaptive Elastic Net方法效果更优.
关键词 ELASTIC NET ADAPTIVE Lasso ADAPTIVE ELASTIC NET Logistic对数线性模型 Oracle性质
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基于混沌PSO优化BP神经网络的碳价预测 被引量:27
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作者 蒋锋 彭紫君 《统计与信息论坛》 CSSCI 北大核心 2018年第5期93-98,共6页
随着全国碳排放权交易市场的启动,碳价的预测对碳市场参与者的风险管理具有重要意义。针对BP神经网络收敛速度慢、容易陷入局部极值的弊端,结合混沌的遍历性,构建基于混沌粒子群(CPSO)算法优化BP神经网络的碳价预测模型:利用Elastic Ne... 随着全国碳排放权交易市场的启动,碳价的预测对碳市场参与者的风险管理具有重要意义。针对BP神经网络收敛速度慢、容易陷入局部极值的弊端,结合混沌的遍历性,构建基于混沌粒子群(CPSO)算法优化BP神经网络的碳价预测模型:利用Elastic Net方法降维,筛选出碳价的主要影响因素;再用CPSO优化BP神经网络的初始权值和阈值训练模型并预测碳价,结果表明:CPSO-BP碳价预测模型的精度和稳定性明显优于传统BP神经网络、粒子群优化的BP神经网络以及果蝇算法优化的BP神经网络。 展开更多
关键词 碳排放权 ELASTIC NET 混沌粒子群算法 BP神经网络 果蝇算法
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一种改进的Lasso方法及其在对数线性模型中的应用 被引量:2
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作者 李春红 黄登香 覃朝勇 《广西大学学报(自然科学版)》 CAS 北大核心 2015年第3期758-765,共8页
变量选择在数据分析中有着重要应用,其参数估计的渐近性质,特别是Oracle性质及组效应性质在变量选择方法上尤其重要。针对Lasso方法一般情形下不具有Oracle性质及组效应性质,将探讨Lasso的一种改进方法,即Adaptive elastic net方法在Poi... 变量选择在数据分析中有着重要应用,其参数估计的渐近性质,特别是Oracle性质及组效应性质在变量选择方法上尤其重要。针对Lasso方法一般情形下不具有Oracle性质及组效应性质,将探讨Lasso的一种改进方法,即Adaptive elastic net方法在Poisson对数线性模型的应用,证明当满足一定条件时,Adaptive elastic net方法估计具有Oracle性质及组效应性质,并利用数值模拟验证其优良性。 展开更多
关键词 ADAPTIVE ELASTIC net方法 Poisson对数线性模型 Oracle性质 组效应
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Electronic Structures and Properties of V, Nb and Ta Metals 被引量:5
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作者 HE Yu,XIE You qing (Department of Materials Science and Engineering, Central South University of Technology, Changsha 410083, China) 《Journal of Central South University》 SCIE EI CAS 2000年第1期7-11,共5页
The electronic structures of pure V, Nb and Ta metals with bcc structure were determined by one atom (OA) theory. According to the electronic structures of these metals, their potential curves, cohesive energies, latt... The electronic structures of pure V, Nb and Ta metals with bcc structure were determined by one atom (OA) theory. According to the electronic structures of these metals, their potential curves, cohesive energies, lattice parameters, elasticity and the dependence of linear thermal expansion coefficients on temperature were calculated. The electronic structures and characteristic properties of these metals with fcc and hcp structures and liquid states were studied. 展开更多
关键词 electronic structure potential curve cohesive energy lattice parameter elasticity linear thermal expansion efficient V NB Ta
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高弹性橡胶联轴器在脉冲负载作用下的动态响应分析 被引量:3
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作者 蔡耀全 吴家明 曾凡明 《船海工程》 2012年第5期112-114,共3页
根据某消磁电站的需要对高弹联轴器的动态特性进行分析,建立双质量的等效转振系统以及相应的动力学方程组。在建立系统振动微分方程的基础上,对高弹性联轴器在脉冲载荷和柴油机输出转矩同时作用下的响应进行数值分析,分析其扭转角度的变... 根据某消磁电站的需要对高弹联轴器的动态特性进行分析,建立双质量的等效转振系统以及相应的动力学方程组。在建立系统振动微分方程的基础上,对高弹性联轴器在脉冲载荷和柴油机输出转矩同时作用下的响应进行数值分析,分析其扭转角度的变化,即第一个脉冲周期的扭转角度峰值响应发生在开始作用时和扭矩达到最大时,最后达到稳态。 展开更多
关键词 elastic coupling pulse DIESEL GENERATOR set IMPULSE load DYNAMICAL PERFORMANCES
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