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An Efficient Multilevel Threshold Image Segmentation Method for COVID-19 Imaging Using Q-Learning Based Golden Jackal Optimization

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Journal of Bionic Engineering 2023年第5期20卷 2276-2316页

作者： Zihao Wang Yuanbin Mo Mingyue Cui School of Artificial Intelligence Guangxi Minzu UniversityNanningChina Guangxi Key Laboratory of Hybrid Computation and IC Design Analysis Guangxi Minzu UniversityNanning530006China

From the end of 2019 until now,the Coronavirus Disease 2019(COVID-19)has been rampaging around the world,posing a great threat to people's lives and health,as well as a serious impact on economic development.Considering the severely infectious nature of COVID-19,the diagnosis of COVID-19 has become crucial.Identification through the use of Computed Tomography(CT)images is an efficient and quick means.Therefore,scientific researchers have proposed numerous segmentation methods to improve the diagnosis of CT images.In this paper,we propose a reinforcement learning-based golden jackal optimization algorithm,which is named QLGJO,to segment CT images in furtherance of the diagnosis of COVID-19.Reinforcement learning is combined for the first time with meta-heuristics in segmentation problem.This strategy can effectively overcome the disadvantage that the original algorithm tends to fall into local optimum.In addition,one hybrid model and three different mutation strategies were applied to the update part of the algorithm in order to enrich the diversity of the population.Two experiments were carried out to test the performance of the proposed algorithm.First,compare QLGJO with other advanced meta-heuristics using the IEEE CEC2022 benchmark functions.Secondly,QLGJO was experimentally evaluated on CT images of COVID-19 using the Otsu method and compared with several well-known meta-heuristics.It is shown that QLGJO is very competitive in benchmark function and image segmentation experiments compared with other advanced meta-heuristics.Furthermore,the source code of the QLGJO is publicly available at https://***/Vang-z/QLGJO.

关键词： COVID-19 Bionic algorithm Golden jackal optimization Image segmentation Otsu and Kapur method

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Renewable Microgrid Protection Strategy Coordinating with Current-based Fault Control

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Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1679-1689页

作者： Zihao Wang Longhua Mu Chongkai Fang College of Electronics and Information Engineering Tongji UniversityShanghai 201804China

The renewable microgrid(RMG)is a critical way to organize and utilize new energy.Its control and protection strategies during the fault are the core technologies to ensure the safe operation and stability of the system.The traditional protection principles are unsuitable for RMGs due to the flexibility of RMG operation,the complexity of RMG topology,and the variety of fault control strategies of inverter-interfaced distributed generators(IIDGs).The traditional fault component protection principle is affected by the low voltage ride-through(LVRT)control strategy and will fail in some scenarios.In order to make the fault component protection principle available in every scenario,a current-based fault control strategy is proposed.Specific fault characteristics are generated by the grid-feeding IIDGs during the fault so they can be equivalent to the open circuits,and the fault models in additional network can be simplified.By analyzing the fault characteristics,an RMG protection strategy based on the current-based fault control of IIDGs is presented.The fault directions of feeders can be distinguished and the fault feeder can be located accurately in both grid-connected and islanded RMGs.Then,the grid-feeding IIDGs can transit to LVRT mode smoothly.Thus,IIDGs are considered comprehensively in terms of coordinating with fault control and fault characteristic generation.Finally,the experimental results of the hardware platform prove the effectiveness of the proposed current-based fault control strategy,and the simulation results based on PSCAD/EMTDC verify the correctness of the protection strategy.

关键词： Renewable microgrid protection strategy fault characteristic control strategy fault component

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Yamabe-harmonic flow on locally conformally flat manifolds

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Acta Mathematica Sinica,English Series 2024年

作者： Zihao Wang School of Mathematics and Statistics Wuhan University

In this paper we introduce a new geometric flow consisting of the Yamabe flow coupled with harmonic heat flow of a function on a closed manifold M, or shortly Yamabe-harmonic flow. It is define by ■ To begin with we establish the short-time extsience via conformal transformation for any smooth initial data. Furthermore we derive interior-in-time derivative estimates for the Riemannian curvature and Lapse function and obtain the global existence of Yamabe-harmonic flow. Moreover, compact gradient Yamabe-harmonic solitons are proved to be manifolds with R=φ=Constant. Eventually we obtain the classification of singularities by blow-up rate of AC curvature, which is analogous to that of Ricciharmonic flow and Ricci-connection flow. The relationship between singularity models and solitons shall appear in forthcoming work.

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Fracture of films caused by uniaxial tensions:a numerical model

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Applied Mathematics and Mechanics(English Edition) 2023年第12期44卷 2093-2108页

作者： Chenxue JIA Zihao Wang Donghui ZHANG Taihua ZHANG Xianhong MENG School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Space Utilization Technology and Engineering Center for Space UtilizationChinese Academy of SciencesBeijing 100094China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

Surface cracks are commonly observed in coatings and films.When structures with coatings are subject to stretching,opening mode cracks are likely to form on the surface,which may further lead to other forms of damage,such as interfacial delamination and substrate damage.Possible crack forms include cracks extending towards the interface and channeling across the film.In this paper,a two-dimensional numerical model is proposed to obtain the structural strain energy at arbitrary crack lengths for bilayer structures under uniaxial tension.The energy release rate and structural stress intensity factors can be obtained accordingly,and the effects of geometry and material features on fracture characteristics are investigated,with most crack patterns being confirmed as unstable.The proposed model can also facilitate the analysis of the stress distribution in periodic crack patterns of films.The results from the numerical model are compared with those obtained by the finite element method(FEM),and the accuracy of the theoretical results is demonstrated.

关键词： surface crack numerical model stress intensity factor periodic crack finite element method(FEM)

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Quantitative determination of the electron beam radiation dose for SARS-CoV-2 inactivation to decontaminate frozen food packaging

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Virologica Sinica 2022年第6期37卷 823-830页

作者： Zihao Wang Zhentao Liang Rongguo Wei Hongwei wang Fang Cheng Yang Liu Songdong Meng Key Laboratory of Pathogenic Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing100101China University of Chinese Academy of Sciences Beijing100049China Department of Clinical Laboratory The Fifth Affiliated Hospital of Guangxi Medical UniversityNanning530022China China Isotope and Radiaton Corporation Beijing100089China Changchun CNNC CIRC Radiation Technology Co. LTDChangchun130022China

The spread of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) from cold-chain foods to frontline workers poses a serious public health threat during the current global pandemic. There is an urgent need to design concise approaches for effective virus inactivation under different physicochemical conditions to reduce the risk of contagion through viral contaminated surfaces of cold-chain foods. By employing a time course of electron beam exposure to a high titer of SARS-CoV-2 at cold-chain temperatures, a radiation dose of 2 kGy was demonstrated to reduce the viral titer from 10^(4.5)to 0 median tissue culture infectious dose(TCID_(50))/mL. Next,using human coronavirus OC43(HCoV-OC43) as a suitable SARS-CoV-2 surrogate, 3 kGy of high-energy electron radiation was defined as the inactivation dose for a titer reduction of more than 4 log units on tested packaging materials. Furthermore, quantitative reverse transcription PCR(RT-qPCR) was used to test three viral genes,namely, E, N, and ORF1ab. There was a strong correlation between TCID50and RT-qPCR for SARS-CoV-2detection. However, RT-qPCR could not differentiate between the infectivity of the radiation-inactivated and nonirradiated control viruses. As the defined radiation dose for effective viral inactivation fell far below the upper safe dose limit for food processing, our results provide a basis for designing radiation-based approaches for the decontamination of SARS-CoV-2 in frozen food products. We further demonstrate that cell-based virus assays are essential to evaluate the SARS-CoV-2 inactivation efficiency for the decontaminating strategies.

关键词： Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) Inactivation Electron beam radiation Food decontamination Cold-chain

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Graph representation learning-based residential electricity behavior identification and energy management

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Protection and Control of Modern Power Systems 2023年第2期8卷 218-230页

作者： Xinpei Chen Tao Yu Zhenning Pan Zihao Wang Shengchun Yang School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China China Electric Power Research Institute Nanjing 210003China

It is important to achieve an efficient home energy management system(HEMS)because of its role in promoting energy saving and emission reduction for end-users.Two critical issues in an efficient HEMS are identification of user behavior and energy management strategy.However,current HEMS methods usually assume perfect knowledge of user behavior or ignore the strong correlations of usage habits with different applications.This can lead to an insuffi-cient description of behavior and suboptimal management strategy.To address these gaps,this paper proposes non-intrusive load monitoring(NILM)assisted graph reinforcement learning(GRL)for intelligent HEMS decision making.First,a behavior correlation graph incorporating NILM is introduced to represent the energy consumption behavior of users and a multi-label classification model is used to monitor the loads.Thus,efficient identification of user behavior and description of state transition can be achieved.Second,based on the online updating of the behavior correlation graph,a GRL model is proposed to extract information contained in the graph.Thus,reliable strategy under uncer-tainty of environment and behavior is available.Finally,the experimental results on several datasets verify the effec-tiveness of the proposed model.

关键词： Behavior correlation graph Graph reinforcement learning Home energy management system Multi-label classification Non-intrusive load monitoring

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Role of innate immunity in SARS-CoV-2 infection

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Biosafety and Health 2023年第5期5卷 280-288页

作者： Zihao Wang Fang Cheng Yuxiu Xu Xin Li Songdong Meng Key Laboratory of Pathogen Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

During severe acute respiratory syndrome coronavirus 2(SARS‐CoV‐2)infection,activated macrophages,dendritic cells(D.C.),neutrophils,and natural killer(N.K.)cells are the first defense against infection.These immune effectors trap and ingest the virus,kill infected epithelial cells,or produce anti‐viral cytokines.Evidence suggests that aging,obesity,and mental illness can lead to weakened innate immunity and,thus,are all associated with elevated infection and severe disease progression of coronavirus disease 2019(COVID‐19).Innate immune defense networks play a fundamental role in suppressing viral replication,infection establishment,and viral pathogenesis of SARS‐CoV‐2 and other respiratory viruses.

关键词： Innate immunity SARS‐CoV‐2 Traditional Chinese medicine Depression Heat shock protein

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Third-order polynomial model for analyzing stickup state laminated structure in flexible electronics

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Acta Mechanica Sinica 2018年第1期34卷 48-61页

作者： Xianhong Meng Zihao Wang Boya Liu Shuodao wang School of Aeronautic Science and Engineering Beihang University Beijing 100191 China School of Mechanical and Aerospace Engineering Oklahoma State University Stillwater OK 74078 USA

Laminated hard-soft integrated structures play a significant role in the fabrication and development of flexible electronics devices. Flexible electronics have advantageous characteristics such as soft and light-weight, can be folded,twisted, flipped inside-out, or be pasted onto other surfaces of arbitrary shapes. In this paper, an analytical model is presented to study the mechanics of laminated hard-soft structures in flexible electronics under a stickup state. Thirdorder polynomials are used to describe the displacement field,and the principle of virtual work is adopted to derive the governing equations and boundary conditions. The normal strain and the shear stress along the thickness direction in the bimaterial region are obtained analytically, which agree well with the results from finite element analysis. The analytical model can be used to analyze stickup state laminated structures, and can serve as a valuable reference for the failure prediction and optimal design of flexible electronics in the future.

关键词： Flexible electronics Stickup state Third-order polynomials Virtual work principle

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Microgrid Fault Detection Method Coordinated with a Sequence Component Current-Based Fault Control Strategy

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Protection and Control of Modern Power Systems 2024年第1期9卷 81-93页

作者： Zihao Wang Longhua Mu Tongji University ShanghaiChina College of Electronics and Information Engineering Tongji UniversityShanghai 201804China

The fault characteristics of microgrids are affected by the penetration of inverter-interfaced distributed generators(IIDGs).It makes conventional protection schemes no longer applicable.With different grid codes in different countries,IIDGs need to adopt different positive-sequence low-voltage ride-through(LVRT)control strategies during LVRT.Therefore,conventional protection schemes have to be modified according to the specific microgrid structure and the IIDGs’LVRT strategy.In order to adapt to different grid codes,a sequence component current-based fault control strategy and a coordinated microgrid fault detection method are proposed in this paper.The fault control strategy of IIDGs comprehensively considers the coordination between voltage support and fault characteristics generation,where the sequence currents are controlled separately.The positive-sequence current control strategy aims at supporting the microgrid voltage,whereas the negative-sequence current control strategy aims at generating or enhancing specific fault characteristics.Based on the proposed fault control strategy,the grid-feeding IIDGs can be equivalent to current sources and generate or enhance the negative-sequence fault characteristics in the equivalent additional networks of negative-sequence components.The fault feeder can then be accurately located by analyzing the phase relationship between the negative-sequence fault components of voltage and current phasors.A coor-dinated microgrid fault detection method based on the fault control strategy of IIDGs is proposed.The proposed fault control method makes the fault component protection principle applicable to all types of faults under any operational modes of microgrids.Finally,the correctness and effectiveness of the proposed coordinated fault control and protection strategy are verified in PSCAD/EMTDC.

关键词： fault applicable generating

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Analytical study of wrinkling in thin-film-on-elastomer system with finite substrate thickness

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Applied Mathematics and Mechanics(English Edition) 2017年第4期38卷 469-478页

作者： Xianhong MENG Guanyu LIU Zihao Wang Shuodao wang School of Aeronautic Science and Engineering Beihang University School of Mechanical and Aerospace Engineering Oklahoma State University

Surface wrinkling, a film bonded on a pre-strained elastomeric substrate can form periodic wrinkling patterns, is a common phenomenon in daily life. In existing theoretical models, the film is much thinner than the substrate so that the substrate can be considered to be elastomeric with infinite thickness. In this paper, the effect of finite substrate thickness is analyzed theoretically for free boundary condition cases. Based on the minimum potential energy principle, a theoretical model is established, and the wave length and amplitude of the wrinkling pattern are obtained. When the thickness of the substrate is more than 200 times larger than the thickness of the film, the results of this study agree well with the results obtained from the previous models for infinite substrate thickness. However, for thin substrates, the effect of finite substrate thickness becomes significant. The model given in this paper accurately describes the effect of finite substrate thickness, providing important design guidelines for future thin-film-on-substrate systems such as stretchable electronic devices.

关键词： wrinkling finite substrate thickness theoretical mechanics model

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