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Yue Sun Aidong Xu Kai Wang Xiufang Zhou Haifeng Guo Xiaojia Han 《Entropy (Basel, Switzerland)》2022,24(7)
One of the biggest challenges for the fault diagnosis research of industrial robots is that the normal data is far more than the fault data; that is, the data is imbalanced. The traditional diagnosis approaches of industrial robots are more biased toward the majority categories, which makes the diagnosis accuracy of the minority categories decrease. To solve the imbalanced problem, the traditional algorithm is improved by using cost-sensitive learning, single-class learning and other approaches. However, these algorithms also have a series of problems. For instance, it is difficult to estimate the true misclassification cost, overfitting, and long computation time. Therefore, a fault diagnosis approach for industrial robots, based on the Multiclass Mahalanobis-Taguchi system (MMTS), is proposed in this article. It can be classified the categories by measuring the deviation degree from the sample to the reference space, which is more suitable for classifying imbalanced data. The accuracy, G-mean and F-measure are used to verify the effectiveness of the proposed approach on an industrial robot platform. The experimental results show that the proposed approach’s accuracy, F-measure and G-mean improves by an average of 20.74%, 12.85% and 21.68%, compared with the other five traditional approaches when the imbalance ratio is 9. With the increase in the imbalance ratio, the proposed approach has better stability than the traditional algorithms. 相似文献
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针对三片式数字光处理投影机光学系统中分色合色结构复杂、重量大、后焦距长的问题,提出了一种利用一个分色棱镜和两个二向色性滤色片来实现分色合色的方法。数字光处理投影机所用的光调制元件是数字微镜器件DMD,它是利用转动微反射镜改变反射光束的出射方向来实现光阀作用的。基于这一特点,通过精心安排分色棱镜和合色片的空间位置来实现对照明光束的分色以及对调制光束的合色功能。系统光学元件重量仅36 g,通过软件模拟本系统具有良好的色彩还原能力,光利用率达60%,还具有结构简单,对比度高等优点。 相似文献
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图像去模糊一直是图像修复中的重要问题,针对经典的去模糊方法,提出一种耦合非凸lp(0≤p<1)范数和G范数的图像去模糊方法。该方法利用lp(0≤p<1)范数作为正则项约束,保证了图像的稀疏性要求;利用G范数作为保真项,保证在去模糊的同时有效抑制噪声并保持图像的细小特征,同时也给出新方法基于交替最小化的有效算法。实验结果表明新模型是可行的。 相似文献
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Yan Shen Huayong Xu Xiangang Xu Qing Liu Huan Liu Kai Jiang Xiaobo Hu 《Materials Science in Semiconductor Processing》2013,16(6):1719-1722
A thin film consisting of a disordered nanorod network of indium tin oxide (ITO) and conventional ITO films are fabricated on gallium nitride (GaN) based-light emitting diodes (LEDs) by electron beam evaporation. The surface morphologies are observed by scanning electron microscopy (SEM). The disordered nanorod network of ITO is grown in vacuum without oxygen. It can be applied directly on the LED as the current spreading film unlike other nanorods which require growth on a conductive layer. The transmittance, current–voltage characteristic, and the dependence of light output power on current are measured for disordered nanorod network ITO LEDs and conventional ITO LEDs, respectively. The measurement results indicate that the nanorod network provides a significant improvement in the light output power of GaN-based LEDs. The influence of the structure of ITO films on the light output power of GaN-based LEDs is discussed. 相似文献
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Eugene Shi Guang Choo Erwin Peng Reshmi Rajendran Prashant Chandrasekharan Chang‐Tong Yang Jun Ding Kai‐Hsiang Chuang Junmin Xue 《Advanced functional materials》2013,23(4):496-505
This study proposes a new method to generate positive contrast in magnetic resonance imaging (MRI) using superparamagnetic contrast agents. Superparamagnetic nanostructures consisting of octahedron manganese ferrite nanoparticles embedded in spherical nanogels are fabricated using a bottom‐up approach. The composite nanoparticles are strongly magnetized in an external magnetic field and produce a unique NMR frequency shift in water protons, which can be demonstrated in MR spectroscopy and imaging to be different from the bulk pool. Moreover, the particles exhibit excellent colloidal stability in aqueous media and good cell biocompatibility. Hence, these particles are potentially useful as biomarkers by taking advantage of the positive contrast effects produced in MRI. 相似文献
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