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广义布洛赫条件下二维晶格的磁交换作用
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作者 赵红艳 蒋灵子 +3 位作者 朱岩 潘燕飞 樊济宇 马春兰 《物理学报》 SCIE EI CAS CSCD 北大核心 2022年第1期243-253,共11页
二维磁性材料是近几年新兴的研究领域,该材料在开发自旋电子器件等领域具备良好的应用潜能.为了了解二维磁性材料的磁性质,明确体系内各近邻磁性原子间的磁相互作用非常重要.第一性原理为各近邻磁交换参数的计算奠定了基础.目前各近邻... 二维磁性材料是近几年新兴的研究领域,该材料在开发自旋电子器件等领域具备良好的应用潜能.为了了解二维磁性材料的磁性质,明确体系内各近邻磁性原子间的磁相互作用非常重要.第一性原理为各近邻磁交换参数的计算奠定了基础.目前各近邻参数的第一性原理计算常用的是能量映射法,但这种方法存在一定的缺陷.本文通过广义布洛赫条件推导了3种常见二维磁性结构的海森伯作用与Dzyaloshinskii-Moriya(DM)相互作用的自旋螺旋色散关系,这3种结构为四方结构,元胞包含一个磁性原子的六角结构,元胞包含两个磁性原子的六角结构.为了将本文推导的自旋螺旋色散关系应用于实际,我们通过第一性原理计算了一些材料的海森伯和DM作用的交换参数,这些材料分别是MnB,VSe_(2),MnSTe,Cr_(2)I_(3)C_(l3).其中,MnSTe和Cr_(2)I_(3)C_(l3)都属于二维Janus材料,磁性原子层的上下层对称性破缺,整个体系存在DM相互作用. 展开更多
关键词 二维磁性结构 磁相互作用 广义布洛赫条件 第一性原理
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Improved pedestrian detection with peer AdaBoost cascade 被引量:4
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作者 FU Hong-pu ZOU Bei-ji +3 位作者 ZHU Cheng-zhang DAI Yu-lan jiang ling-zi CHANG Zhe 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第8期2269-2279,共11页
Focusing on data imbalance and intraclass variation,an improved pedestrian detection with a cascade of complex peer AdaBoost classifiers is proposed.The series of the AdaBoost classifiers are learned greedily,along wi... Focusing on data imbalance and intraclass variation,an improved pedestrian detection with a cascade of complex peer AdaBoost classifiers is proposed.The series of the AdaBoost classifiers are learned greedily,along with negative example mining.The complexity of classifiers in the cascade is not limited,so more negative examples are used for training.Furthermore,the cascade becomes an ensemble of strong peer classifiers,which treats intraclass variation.To locally train the AdaBoost classifiers with a high detection rate,a refining strategy is used to discard the hardest negative training examples rather than decreasing their thresholds.Using the aggregate channel feature(ACF),the method achieves miss rates of 35%and 14%on the Caltech pedestrian benchmark and Inria pedestrian dataset,respectively,which are lower than that of increasingly complex AdaBoost classifiers,i.e.,44%and 17%,respectively.Using deep features extracted by the region proposal network(RPN),the method achieves a miss rate of 10.06%on the Caltech pedestrian benchmark,which is also lower than 10.53%from the increasingly complex cascade.This study shows that the proposed method can use more negative examples to train the pedestrian detector.It outperforms the existing cascade of increasingly complex classifiers. 展开更多
关键词 peer classifier hard negative refining pedestrian detection CASCADE
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