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题名超磁致伸缩材料内部磁场特性及材料参数对其影响分析
被引量:17
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作者
袁惠群
孙华刚
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机构
东北大学
中国振动工程学会
辽宁省振动工程学会
总装备部军械技术研究所
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出处
《中国电机工程学报》
EI
CSCD
北大核心
2008年第30期119-124,共6页
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基金
国家自然科学基金项目(10772043)~~
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文摘
基于麦克斯韦方程和压磁理论建立了超磁致伸缩材料棒内的磁场分布模型,导出了含有材料磁弹性参数的超磁致伸缩材料棒磁场分布函数,讨论了材料特性参数对材料内部磁场和材料内部涡流损耗的影响。结果表明,材料内部磁场不仅与外激励磁场有关,而且与材料的压磁系数、杨氏模量及相对磁导率有关,同时材料内部磁场与外激励磁场间具有滞回特性;考虑材料特性参数时材料内部的涡流损耗达到最大值所需的材料半径,将大于不考虑材料特性参数时的半径值,同时涡流损耗的变化趋势也将变得和缓,而不论材料参数如何变化,超磁致伸缩棒内磁能损耗的基本规律没有发生变化。
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关键词
超磁致伸缩材料
内部磁场分布模型
开尔文-贝塞尔函数
材料特性参数
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Keywords
giant magnetostrictive materials
inner magnetic field distribution model: kelvin-bessel function
material characteristic parameters
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分类号
TM153
[电气工程—电工理论与新技术]
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题名超磁致伸缩材料磁滞回非线性特性分析
被引量:3
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作者
袁惠群
孙华刚
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机构
东北大学理学院
总装备部军械技术研究所
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出处
《兵工学报》
EI
CAS
CSCD
北大核心
2009年第2期180-184,共5页
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基金
国家自然科学基金项目资助(10772043)
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文摘
在对考虑材料特性参数的超磁致伸缩材料内部等效磁场分析的基础上,将时变磁场下的涡流影响引入Jiles-Atherton模型,对其进行修正,建立考虑材料内部磁场特性的磁滞回非线性模型,导出相应的解析表达式。通过数值模拟讨论材料参数对滞回非线性特性的影响,并与文献[21]实验比较。结果表明:材料内部磁滞回特性不仅受激励磁场频率的影响,而且还与材料内部磁场分布有着密切的关系;当考虑材料内部磁场分布时,材料的磁滞回曲线的最大值将明显降低,滞回曲线的形状也将发生变化,而所得非线性滞回模型与实验结果更加吻合。
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关键词
电磁学
超磁致伸缩材料
内部磁场分布
磁滞回非线性模型
材料参数
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Keywords
electromagnetics
giant magnetostrictive materials
inner magnetic field distribution
nonlinearity hysteresis model
material parameters
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分类号
TH703
[机械工程—精密仪器及机械]
O32
[理学—一般力学与力学基础]
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题名多巴胺系统基因对注意网络的调控作用
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作者
陈晨
张英
刘嘉
胡思源
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机构
北京师范大学心理学部应用实验心理北京市重点实验室心理学国家级实验教学示范中心(北京师范大学)
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出处
《心理科学》
CSSCI
CSCD
北大核心
2018年第1期24-30,共7页
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基金
国家自然科学基金青年科学基金项目(31000507)的资助
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文摘
多巴胺是脑内重要的神经递质之一,与注意活动紧密相关。本文选取作用于突触前膜、间隙和后膜的多巴胺系统基因——多巴胺转运蛋白基因、儿茶酚氧化甲基转移酶基因和多巴胺受体基因,整合影像遗传学研究,探讨多巴胺基因对注意网络的调控。元分析发现背侧和腹侧注意网络的主要脑区均有较大的基因调控效应,且腹侧网络的效应值显著大于背侧网络,表明多巴胺系统基因在全脑范围内调控注意网络,且对腹侧网络的调控作用强于背侧网络。
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关键词
注意网络
功能磁共振成像
影像遗传学
多巴胺系统
元分析
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Keywords
included but not limited to functional magnetic resonance imaging (tMRI), and candidate doparninergic system genes targeting at the presynaptic, the postsynaptie neurons, or the synaptic cleft, such as the dopamine transporter gene (DAT), the catechol-O-methyltransferase gene (COMT) or the dopamine receptor gene (DRD). Reference lists were checked by hand and a total of forty-four papers were gathered and applied to our meta-analysis. We extracted the coordinates of peak voxels where the genetic modulatory effect on attention was reported in the papers and then projected them onto a brain template in Caret to visualize the distribution of the modulatory effects of genes. The effect sizes were calculated using Cohen's d to quantify the magnitude of activation differences between the subjects with separate ganotypes in each att
ntion task. The random-effects model was chosen for the meta-analysis and the effect sizes of effective modulation of dopaminergie system genes in different brain regions were calculated with Comprehensive Meta-Analysis program (CMA). To compare the differences across attention networks and dopaminergic genes, the Q-test of homogeneity was used to test for variations in effect sizes. Our results showed that the integrated effect sizes of effective modulation of dopaminergic system genes were all above .8 (Cohen's d) in the ventral attention network (VAN), including the ventral prefrontal cortex (VLPFC), the orbitofrontal gyms (OFG), and the superior temporal gyms (STG), and also in the dorsal attention network (DAN), consisting of the dorsolateral prefrontal cortex (DLPFC), the superior parietal lobule (SPL) and the frontal eye field (FEF). The VAN presented a significantly higher effect size in comparison to the DAN (Qb = 4.94,p 〈 .05). In addition, the variation test of effect sizes for dopaminergic system genes showed that the COMT gene exhibited a significantly higher effect size than that of DAT gene (Qb = 77.04,p 〈 .001) and DRD gene (Qb = 186.35,p 〈 .001). Our study suggests the important role of the dopaminergic system genes in regulating attention networks in the whole brain. As DAN enables the selection of sensory stimuli based on internal goals and VAN detects salient and relevant stimuli in the environment. The observed stronger modulatory effect of dopaminergic system genes in VAN than in DAN suggests that bottom-up attention, compared with top-down attention, receives more modulation from genes than from the environment. Our study invites broader and deeper studies on the relationship between the genes, the brain, and the attentional behaviors at the network level in the future. Key words attention networks, MRI, imaging genetics, doparninergic system, meta-anaiysis
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分类号
R338
[医药卫生—人体生理学]
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