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312 results on '"Zhang, Zhengyuan"'

62. A Box-Counting Method for Characteristic Diagnosis of Nonlinear Dynamical Systems.

Author

Zhang, Zhengyuan and Dai, Liming

Subjects
*POINCARE maps (Mathematics), *NONLINEAR dynamical systems, *DIAGNOSIS methods, *NONLINEAR systems, *TOPOLOGICAL property
Abstract

An innovative box-counting method is developed in this research for diagnozing the nonlinear characteristics of dynamical systems. With the method developed, an approach that depicts the evolutionary process on Poincaré maps is established such that the nonlinear dynamical characteristics of the transient and stable process of the system can be graphically and quantitatively identified. A Duffing–van der Pol system is adopted in the research to demonstrate an application of the method. A diagram graphically describing the periodic, quasiperiodic, chaotic, and transient chaotic regions of the system's responses is constructed based on the method. Furthermore, the nature of different box-point curves is explained based on the topology of chaos and quasiperiodicity. The method developed shows innovation and efficiency in diagnozing nonlinear dynamical systems based on the topological properties of general nonlinear systems. [ABSTRACT FROM AUTHOR]

Published
2023
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68. Time-Dependent Hot Carrier Degradation in Polysilicon Emitter Bipolar Transistors Under High Current and Radiation Combined Stress

Author

Liu Jian, Chao Chen, Qiu Sheng, Min Hong, Jianqun Yang, Zicheng Xu, Tao Wang, Xingji Li, Peijian Zhang, Zhihua Feng, Jian Li, Jiao Liu, Wensuo Chen, Xianchao Wen, Yan Wang, Zhang Zhengyuan, Zhu Kunfeng, Guangsheng Zhang, Ruijin Liao, and Chen Xian

Subjects
Materials science, business.industry, Bipolar junction transistor, Transistor, Dangling bond, Radiation, Noise (electronics), Electronic, Optical and Magnetic Materials, law.invention, Auger, law, Optoelectronics, Grain boundary, Electrical and Electronic Engineering, business, Common emitter
Abstract

A comparative combined stress-induced reliability issues between Auger hot carrier and ionizing radiation in double polysilicon bipolar transistor is investigated. The observed differences in the low-frequency noise spectra of devices with different stressing conditions could be interpreted as the differences in the defects-related noise contributions. Low-frequency noise and electrical performance degradation results show that Auger hot carriers greatly induce the atomic hydrogen depassivating the dangling bonds in grain boundaries of emitter polysilicon. However, ionizing radiation damage occurs both at SiO2/Si interfaces and in the oxide layer. 1/f noise characteristics indicate that these two damages have different time dependences.

Published
2021

77. Induction of human pluripotent stem cells from human somatic cells by chemical reprogramming

Author

Deng, Hongkui, primary, Guan, Jingyang, additional, Wang, Guan, additional, Wang, Jinlin, additional, Zhang, Zhengyuan, additional, Fu, Yao, additional, Cheng, Lin, additional, Meng, Gaofan, additional, Zhu, Jialiang, additional, Wang, Yanglu, additional, Liuyang, Shijia, additional, Yang, Zirun, additional, He, Huanjing, additional, Zhong, Xinxing, additional, and Chen, Qijing, additional

Published
2022
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79. Adaptive Enhancement of Acoustic Resolution Photoacoustic Microscopy Imaging Via Deep CNN Prior

Author

Zhang, Zhengyuan, Jin, Haoran, Zhang, Wenwen, Lu, Wenhao, Zheng, Zesheng, Sharma, Arunima, Pramanik, Manojit, Zheng, Yuanjin, and School of Electrical and Electronic Engineering

Subjects
History, Deep Learning, Editorial, Polymers and Plastics, Electrical and electronic engineering [Engineering], Acoustic Resolution, Radiology, Nuclear Medicine and imaging, Business and International Management, Atomic and Molecular Physics, and Optics, Industrial and Manufacturing Engineering
Abstract

Acoustic resolution photoacoustic microscopy (AR-PAM) is a promising medical imaging modality that can be employed for deep bio-tissue imaging. However, its relatively low imaging resolution has greatly hindered its wide applications. Previous model-based or learning-based PAM enhancement algorithms either require design of complex handcrafted prior to achieve good performance or lack the interpretability and flexibility that can adapt to different degradation models. However, the degradation model of AR-PAM imaging is subject to both imaging depth and center frequency of ultrasound transducer, which varies in different imaging conditions and cannot be handled by a single neural network model. To address this limitation, an algorithm integrating both learning-based and model-based method is proposed here so that a single framework can deal with various distortion functions adaptively. The vasculature image statistics is implicitly learned by a deep convolutional neural network, which served as plug and play (PnP) prior. The trained network can be directly plugged into the model-based optimization framework for iterative AR-PAM image enhancement, which fitted for different degradation mechanisms. Based on physical model, the point spread function (PSF) kernels for various AR-PAM imaging situations are derived and used for the enhancement of simulation and in vivo AR-PAM images, which collectively proved the effectiveness of proposed method. Quantitatively, the PSNR and SSIM values have all achieve best performance with the proposed algorithm in all three simulation scenarios; The SNR and CNR values have also significantly raised from 6.34 and 5.79 to 35.37 and 29.66 respectively in an in vivo testing result with the proposed algorithm. Ministry of Education (MOE) Published version This research is supported by the Ministry of Education, Singapore, under its MOE ARF Tier 2 (Award no. MOE2019-T2-2-179).

Published
2022

88. Time-Dependent Hot Carrier Degradation in Polysilicon Emitter Bipolar Transistors Under High Current and Radiation Combined Stress

Author

Zhang, Peijian, primary, Xu, Zicheng, additional, Wang, Tao, additional, Chen, Wensuo, additional, Hong, Min, additional, Zhu, Kunfeng, additional, Liu, Jiao, additional, Chen, Xian, additional, Liu, Jian, additional, Zhang, Guangsheng, additional, Qiu, Sheng, additional, Wang, Yan, additional, Feng, Zhihua, additional, Zhang, Zhengyuan, additional, Wen, Xianchao, additional, Chen, Chao, additional, Li, Xingji, additional, Yang, Jianqun, additional, Li, Jian, additional, and Liao, Ruijin, additional

Published
2021
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90. Influence Mechanism of Gas Turbine Blade Thickness on Photoacoustic Signals to Guide Defect Imaging Detection

Author

Qin, Feng, Li, Bing, Chen, Lei, Tang, Tao, Wang, Zhuqing, Huang, Yu, Zhang, Zhenlong, Zhang, Zhengyuan, and Zheng, Yuanjin

Abstract

It is necessary to study the influence mechanism of blade thickness on the photoacoustic signals since material thickness will affect defect detection precision by affecting the types, velocity, and frequency of photoacoustic signals. In this article, the influence mechanism of blade thickness on sound waves is obtained by setting defects with different depths in different thicknesses areas of blades. This mechanism instructs the imaging detection and characterization of defects with different depths in different thicknesses. First, by combining with the dispersion curves, we found that there are more anti-symmetric $A_{0}$ modes in thin area. Second, different types of sound waves lead to different velocities of sound waves. The sound velocity in the thin area of the blades is 2747.58 m/s, and the sound velocity in the thick area is 2912.22 m/s. Further, compared with the thick area, the thin area has more peaks and more complex high-frequency components, but the frequency range is basically the same. Finally, the detection and characterization of blade defects are carried out by combining imaging inspection and influence mechanism. The research results can not only promote the basic research on the influence of thickness on photoacoustic signals, but also expand the application of laser ultrasound in blade defect detection.

Published
2023
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92. Robotic-assisted Versus Video-assisted Thoracoscopic Lobectomy

Author

Jin, Runsen, primary, Zheng, Yuyan, additional, Yuan, Ye, additional, Han, Dingpei, additional, Cao, Yuqin, additional, Zhang, Yajie, additional, Li, Chengqiang, additional, Xiang, Jie, additional, Zhang, Zhengyuan, additional, Niu, Zhenyi, additional, Lerut, Toni, additional, Lin, Jules, additional, Abbas, Abbas E., additional, Pardolesi, Alessandro, additional, Suda, Takashi, additional, Amore, Dario, additional, Schraag, Stefan, additional, Aigner, Clemens, additional, Li, Jian, additional, Che, Jiaming, additional, Hang, Junbiao, additional, Ren, Jian, additional, Zhu, Lianggang, additional, and Li, Hecheng, additional

Published
2021
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93. Review of Approaches to Developing Intersegmental Plane during Segmentectomy.

Author

Chen, Xingshi, Zhang, Zhengyuan, Xu, Ning, Ma, Dongchun, and Li, Hecheng

Subjects
*COMPUTED tomography, *LUNG cancer, *SURGICAL equipment
Abstract

In recent years, with the popularity of computed tomography (CT) scanning, early lung cancer has been found in a large number of patients, and segmentectomy has been widely used in clinical practice. The development of intersegmental plane is the most critical step in segmentectomy. At present, there are many methods to identify the intersegmental plane. Also, dissection of the intersegmental plane has been a challenge for thoracic surgeons for decades because of the complicated anatomic variations. This study focuses on the safety and efficacy of relevant methods in both identification and dissection of the intersegmental plane in segmentectomy. [ABSTRACT FROM AUTHOR]

Published
2022
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97. Light emission from a poly-silicon device with carrier injection engineering

Author

Kaikai Xu, Zhang Zhengyuan, Jianming Zhao, Jacobus W. Swart, Huang Lei, Lukas W. Snyman, and Zhengping Zhang

Subjects
010302 applied physics, Materials science, Silicon, Band gap, business.industry, Mechanical Engineering, chemistry.chemical_element, Integrated circuit, Condensed Matter Physics, 01 natural sciences, law.invention, 010309 optics, chemistry, Mechanics of Materials, law, 0103 physical sciences, Optoelectronics, General Materials Science, Optical radiation, Light emission, business, p–n junction, Diode, Visible spectrum
Abstract

Development work was conducted on N+PN+PN+ Poly silicon light-emitting devices which are compatible with silicon-based integrated circuit technology. We discuss the emission characteristics of visible light by a monolithically integrated Poly-Si diode under reverse bias. With the structure of modified PN junctions, the carriers injection occurs through silicon slabs of only a few nanometer thick. The dominant role of non-radiative recombination at the N+ and P+ contacts is diminished by confining the injected carriers around the PN junction’s interface in which avalanche takes place. The current-dependent optical radiation presents a broad spectrum in the 400- to 900-nm range. Although the emission efficiency is low due to silicon’s indirect bandgap, it is advantageous to utilize these devices in all-silicon optoelectronic integrated circuits (OIC’s).

Published
2018

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