1 陆军军医大学 (第三军医大学)生物医学工程与影像医学系，重庆 400038
2 解放军 75841部队，湖南长沙 410007
3 兰州药品仪器检验所，甘肃兰州 730050
4 陆军军医大学 (第三军医大学)西南医院心内科，重庆 400038
临床上检测异位性心搏，对心血管疾病的早发现、早诊断、早治疗有重大意义。异位性心搏的自动识别能有效减轻人工识别的负担。采用 37只小鼠各 10 min的心电图(ECG)信号，由 3位专家完成异位性心搏的标定及数据库的建立。在此基础上，使用 7种机器学习方法，组合脉冲排除滤波器和模板匹配算法的值，对异位性心搏点进行自动识别。实验结果表明， 7种机器学习的方法都能得到较好的预测性能(所有曲线下面积 (AUC)大于0.899)，其中集成学习 AdaBoost的预测能力最好(AUC=0.940，准确度、特异性均为 0.888)。
异位性心搏 脉冲排除滤波器 模板匹配 机器学习 ectopic beat Impulse Rejection Filter template matching machine learning 太赫兹科学与电子信息学报
2019, 17(5): 866
Author Affiliations
Abstract
1 Shaanxi Joint Laboratory of Graphene, State Key Laboratory Incubation Base of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069, China
2 National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
3 School of Electronic Engineering, Xi’an University of Posts and Telecommunications, Xi’an 710121, China
4 e-mail: xfwang@nju.edu.cn
5 e-mail: rzy@nwu.edu.cn
The prominent third-order nonlinear optical properties of films are studied through the Z-scan technique using a femtosecond pulsed laser at 1030 nm. Open-aperture (OA) and closed-aperture (CA) Z-scan measurements are performed at different intensities to investigate the nonlinear absorption and refraction properties of films. OA Z-scan results show that films always hold a saturable absorption characteristic without transition to reverse saturable absorption. Further, a large nonlinear absorption coefficient is determined to be by fitting the OA Z-scan curve at the peak intensity of . In addition, through the slow saturation absorption model, the ground state absorption cross section, excited state absorption cross section, and absorber’s density were found to be , , and , respectively. CA Z-scan results exhibit a classic peak–valley shape of the CA Z-scan signal, which reveals a self-defocusing optical effect of films under the measured environment. Furthermore, a considerable nonlinear refractive index value can be obtained at . Ultimately, the values of the real and imaginary parts of the third-order nonlinear s
Photonics Research
2019, 7(12): 12001493
1 北京教育网络和信息中心, 北京 100089
2 陆军军医大学(第三军医大学) 生物医学工程与影像医学系, 重庆 400038
3 国防科技大学 电子科学学院, 湖南 长沙 410073
由于高光谱遥感图像的混合程度较高, 使得传统的非负矩阵欠逼近(Nonnegative Matrix Underapproximation, NMU)算法所提取的基本成分仍然“不纯”, 且易受噪声影响。针对这些不足, 提出了一种基于L1/2正则化的软阈值NMU逐次光谱解混算法。首先, 通过引入丰度的L1/2正则项来增强算法的地物区分能力, 进而提高所分离地物的纯度; 其次, 利用软阈值惩罚函数代替NMU中的残差非负约束, 通过调节惩罚因子来控制非负元素的数量, 从而提高算法的抗噪性能。在仿真数据和实测数据上的实验结果表明, 即使在有噪声的条件下, 该算法也能得到较好的分离结果。
高光谱遥感 光谱解混 非负矩阵欠逼近 hyperspectral remote sensing spectral unmixing nonnegative matrix underapproximation 红外与激光工程
2019, 48(7): 0726003
