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AtomGAN:unsupervised deep learning for fast and accurate defect detection of 2D materials at the atomic scale

Science China(Information Sciences) 2023年第6期66卷 102-114页

作者： Danpeng cheng Wuxin SHA Zuo XU Shide LI Zhigao YIN Yuling LANG shun TANG Yuan-cheng CAO State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology School of Computer Science and Technology Huazhong University of Science and Technology CITIC Dicastal Co. Ltd.

The extraction of atomic-level material features from electron microscope images is crucial for studying structure-property relationships and discovering new materials. However, traditional electron microscope analyses rely on time-consuming and complex human operations; thus, they are only applicable to images with a small number of atoms. In addition, the analysis results vary due to observers’ individual deviations. Although efforts to introduce automated methods have been performed previously, many of these methods lack sufficient labeled data or require various conditions in the detection process that can only be applied to the target material. Thus, in this study, we developed AtomGAN, which is a robust, unsupervised learning method, that segments defects in classical 2D material systems and the heterostructures of MoS2/WS2automatically. To solve the data scarcity problem, the proposed model is trained on unpaired simulated data that contain point and line defects for MoS2/WS2. The proposed AtomGAN was evaluated on both simulated and real electron microscope images. The results demonstrate that the segmented point defects and line defects are presented perfectly in the resulting figures, with a measurement precision of 96.9%. In addition, the cycled structure of AtomGAN can quickly generate a large number of simulated electron microscope images.

关键词： deep learning generative adversarial network defect detection atomic resolution 2D materials

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Kinetics of Infection-Driven Growth Model with Birth and Death

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Communications in Theoretical Physics 2008年第9期50卷 787-792页

作者： YANG shun-You ZHU Sheng-Qing KE Jian-Hong LIN zhen-Quan School of Physics and Electronic Information Wenzhou University Wenzhou 325035 China

We propose a two-species infection model, in which an infected aggregate can gain one monomer from a healthy one due to infection when they meet together. Moreover, both the healthy and infected aggregates may lose one monomer because of self-death, but a healthy aggregate can spontaneously yield a new monomer. Consider a simple system in which the birth/death rates are directly proportional to the aggregate size, namely, the birth and death rates of the healthy aggregate of size k are J1 k and J2k while the self-death rate of the infected aggregate of size k is J3k. We then investigate the kinetics of such a system by means of rate equation approach. For the J1 〉 J2 case, the aggregate size distribution of either species approaches the generalized scaling form and the typical size of either species increases wavily at large times. For the J1 = J2 case, the size distribution of healthy aggregates approaches the generalized scaling form while that of infected aggregates satisfies the modified scaling form. For the J1 〈 J2 case, the size distribution of healthy aggregates satisfies the modified scaling form, but that of infected aggregates does not scale.

关键词： kinetic behavior infection birth/death scaling law

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Chaotic Unilateral Weighted Backward Shifts on Sequentially Complete Topological Sequence Spaces

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Acta Mathematica Sinica,English Series 2022年第7期38卷 1285-1293页

作者： zhen RONG cheng LUO Fei HE Ning LU College of Statistics and Mathematics Inner Mongolia University of Finance and EconomicsHohhot 010070P.R.China School of Mathematical Sciences Inner Mongolia UniversityHohhot 010021P.R.China

Extending previous results of Grosse-Erdmann and Peris we obtain a characterization of chaotic unilateral weighted backward shifts on sequentially complete topological sequence spaces in which the canonical unit vecto... 详细信息

关键词： Chaotic operators topological sequence spaces unilateral weighted backward shifts

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Polarity Effects of Propylene Carbonate on Breakdown Strength in Microsecond Range

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： zhen Wang Zi-cheng Zhang Jian-de Zhang College of Opto-electronic Science and Engineering National University of Defense Technology Changsha 410073 China

We investigate the polarity effects of the propylene carbonate on the breakdown voltage using the needle-plate electrodes with gaps of 0.5, 1.0, and 2.0 mm. The devices used in this study involve a compact capacitive-energy-storage pulse power source with charging time varying from 5 ms to 20 ms and a test cell with the needle-plate electrodes. The breakdown voltage is recorded by a digital oscilloscope for each gap. The results of these three groups indicate that the positive breakdown voltage is higher than the negative one and the breakdown voltage of the PC increases with the ascending electrode gap. In addition, a simulation is conducted to support this experiment. Some explanations about the polarity effect of the PC are also given.

关键词： Breakdown strength Propylene carbonate Polarity effect

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Enhanced photocurrent and photoluminescence spectra in MoS2 under ionic liquid gating

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Nano Research 2014年第7期7卷 973-980页

作者： zhen Li shun-Wen Chang Chun-Chung Chen Stephen B. Cronin Department of Electrical Engineering Department of Physics University of Southern California 3737 Watt Way PHE 624 Los Angeles CA 90089 USA

We report substantial improvements and modulation in the photocurrent （PC） and photoluminescence （PL） spectra of monolayer MoS2 recorded under electrostatic and ionic liquid gating conditions. The photocurrent and photo- luminescence spectra show good agreement with a dominant peak at 1.85 eV. The magnitude of the photoluminescence can be increased 300% by ionic liquid gating due to the passivation of surface states and trapped charges that act as recombination centers. The photocurrent also doubles when passivated by the ionic liquid. Interestingly, a significant shift of the PL peak position is observed under electrostatic （14 meV） and ionic liquid （30 meV） gating, as a result of passivation. The ionic liquid provides significant screening without any externally applied voltage, indicating that these surface recombination centers have net charge. The acute sensitivity of monolayer MoS2 to ionic liquid gating and passivation arises because of its high surface-to-volume ratio, which makes it especially sensitive to trapped charge and surface states. These results reveal that, in order for efficient optoelectronic devices to be made from monolayer MoS2, some passivation strategy must be employed to mitigate the issues associated with surface recombination.

关键词： ionic liquid dichalcogenide MoS2 photoluminescence photocurrent passivation

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Amide Ionic Liquids(AILs)/L-Proline Synergistic Catalyzed Asymmetric Mannich Reactions

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Chemical Research in Chinese Universities 2007年第2期23卷 163-168页

作者： LIU Bao-you ZHAO Di-shun XU Dan-qian XU zhen-yuan Key Laboratory of Contaminant Controlling in Biology of Hebei Province College of Environmental Science and Engineering Hebei University of Science and Technology Shijiazhuang 050018 P. R. China State Key Laboratory Breeding Base of Green Chemistry-synthesis Technology Zhejiang University of Technology Hangzhou 310014 P. R. China Pharmaceutical Engineering Research Centre of Hebei Province College of Chemical and Pharmaceutical Engineering Hebei University of Science and Technology Shijiazhuang 050018 P. R. China

Amide ionic liquids （MLs）/L-proline synergistic catalyzed Mannich reactions of isovaleraldehyde, methyl ketones, and aromatic amines were carried out in moderate to high yields （ up to 96% ） and high stereo selectivities （〉99% e. e. ）. The products were easily isolated by extraction; and the catalyst system was readily recycled at least thrice without significant loss of efficiency. The scope of the substrates was studied and the interpretation of the manifest improvement of the reaction rates and enantio-selectivity of the novel catalyst system was speculated.

关键词： Amide ionic liquids (AILs) L-Proline Synergistic catalysis Mannich reaction Asymmetric synthesis β-Aminoketones

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A Numerical Study of the Effect of Multiple Pouring on Macrosegregation in a 438-Ton Steel Ingot

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Acta Metallurgica Sinica(English Letters) 2015年第9期28卷 1123-1133页

作者： zhen-Hu Duan Hou-Fa Shen Bai-cheng Liu Key Laboratory for Advanced Materials Processing Technology Ministry of Education School of Materials Science and Engineering Tsinghua University

In present paper, a ladle-tundish-mold CFD model and a macrosegregation model were utilized to investigate the effects of the multiple pouring （MP） process on the macrosegregation in a 438-ton steel ingot. Firstly, the model was partially proved as compared to the measured carbon distributions along the transverse sections in the riser of ingot. Then, the comparison between the single pouring （SP） and MP process has been carried out to study their influences on the macrosegregation in ingot. Besides, the predicted macrosegregation results in MP process which introduced the improved riser fixed with an insulating sleeve were compared with that in traditional MP process. The traditional MP process leads to certain favorable initial carbon distribution in the mold, which has some favorable influence on suppressing the positive segregation in ingot. The holding time of the low carbon in the riser is the main factor to suppress the positive segregation in ingot. Improved insulating sleeve can prolong the holding time of the low carbon in the riser and release the positive segregation in the riser of ingot. Improvement of the insulating effect of the riser is an efficient method to control macrosegregation in large steel ingot.

关键词： Multiple pouring process Macrosegregation Numerical simulation Large steel ingot

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A Marine Environment Early Warning Algorithm Based on Marine Data Sampled by Multiple Underwater Gliders

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China Ocean Engineering 2019年第2期33卷 172-184页

作者： XU zhen-zhen LI Lu YU Jian-cheng XU Xiu-juan JIA Ming-fei School of Software Technology Dalian University of Technology The State Key laboratory of Robotics Shenyang Institute of AutomationCAS

This study analyzes and summarizes seven main characteristics of the marine data sampled by multiple underwater gliders. These characteristics such as the big data volume and data sparseness make it extremely difficult to do some meaningful applications like early warning of marine environment. In order to make full use of the sea trial data, this paper gives the definition of two types of marine data cube which can integrate the big marine data sampled by multiple underwater gliders along saw-tooth paths, and proposes a data fitting algorithm based on time extraction and space compression(DFTS) to construct the temperature and conductivity data cubes. This research also presents an early warning algorithm based on data cube(EWDC) to realize the early warning of a new sampled data *** results show that the proposed methods are reasonable and effective. Our work is the first study to do some realistic applications on the data sampled by multiple underwater vehicles, and it provides a research framework for processing and analyzing the big marine data oriented to the applications of underwater gliders.

关键词： big marine data early warning marine environment underwater gliders

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Improving Throughput of Communication Link in IEEE 802.15.4 Based Energy-Harvesting Wireless Sensor Network

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Chinese Journal of Electronics 2019年第4期28卷 841-849页

作者： BAI Nana GONG Siliang SHI Haiyan cheng zhen ZHU Yihua School of Computer Science and Technology Zhejiang University of Technology School of Mechanical and Electrical Engineering Shaoxing University

It is critical to design a reliable packet transmission scheme to improve throughput in Energy harvesting Wireless sensor network(EH-WSN) or Battery free Wireless sensor network(BF-WSN). We present the Optimal size and rate(OSR) scheme to improve throughput of communication links in the IEEE 802.15.4 based BF-WSN that harvests radio frequency *** on the defined truncated geometrical distribution,we formulate the optimization problem that maximizes the effective throughput of communication link. The solution of the optimization problem yields the optimal triple,namely the optimal packet size, data rate, and Maximum number of transmission trials(MNTT), which is used in the OSR so that throughput is considerably *** results show the OSR scheme can improve throughput.

关键词： Wireless sensor network Energy harvesting Wireless sensor network Data delivery Throughput

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Discovery of emerging organic pollutants in the atmosphere through an omics approach

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Frontiers of Environmental Science & Engineering 2023年第4期17卷 71-81页

作者： zhen cheng Xinghua Qiu Xiaodi Shi Xing Jiang Tong Zhu State Key Joint Laboratory for Environmental Simulation and Pollution Control College of Environmental Sciences and EngineeringCenter for Environment and HealthPeking UniversityBeijing 100871China

Ambient air pollution,containing numerous known and hitherto unknown compounds,is a major risk factor for public *** discovery of harmful components is the prerequisite for pollution control;however,this raises a great challenge on recognizing previously unknown *** we systematically review the analytical techniques on air pollution in the framework of an omics approach,with a brief introduction on sample preparation and analysis,and in more detail,compounds prioritization and *** high-resolution mass spectrometry(HRMS,typically coupled with chromatography),the complicated environmental matrix can be digitalized into“fullcomponent”data.A key step to discover emerging compounds is the prioritization of compounds from massive *** fingerprints,suspect lists and biological effects are the most vital untargeted strategies for comprehensively screening critical and hazardous ***,compressed data of compounds can be identified at various confidence levels according to exact mass and the derived molecular formula,MS libraries,and authentic *** an omics approach on full-component data provides a paradigm for discovering emerging air pollutants;nonetheless,new technological advancements of instruments and databases are warranted for further tracking the environmental behaviors,hence to evaluate the health risk of key pollutants.

关键词： Air pollution Emerging pollutants Full-component High-resolution mass spectrometry Omics approach

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