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Multi-Cluster Flocking Behavior Analysis for a Delayed Cucker-Smale Model with Short-Range Communication Weight

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Journal of Systems Science & Complexity 2022年第1期35卷 137-158页

作者： QIAO Zhengyang liu yicheng WANG Xiao Department of Mathematics National University of Defense TechnologyChangsha 410073China

This paper analyzes the multi-cluster flocking behavior of a Cucker-Smale model involving delays and a short-range communication *** each sub-flocking group,the velocity between agents is alignment and the position locates at a limited domain;but in different sub-flocking groups,the position between agents is *** constructing dissipative differential inequalities of subensembles together with Lyapunov functional methods,the authors provide the sufficient condition for the multi-cluster flocking *** sufficient condition includes the estimation of the range of coupling strength and the upper bound of time *** a result,the authors show that the coupling strength among agents and initial threshold value determine the multi-cluster flocking behavior of the delayed Cucker-Smale model.

关键词： Cucker-Smale model Lyapunov functional multi-cluster flocking short-range communication weight time-delay systems

A Comprehensive Review for Micro/Nanoscale Thermal Mapping Technology Based on Scanning Thermal Microscopy

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Journal of Thermal Science 2022年第4期31卷 976-1007页

作者： LI Yifan ZHANG Yuan liu yicheng XIE Huaqing YU Wei School of Energy and Materials Shanghai Polytechnic UniversityShanghai 201209China Shanghai Engineering Research Center of Advanced Thermal Functional Materials Shanghai Polytechnic UniversityShanghai 201209China

Thermal characterization becomes challenging as the material size is reduced to micro/*** on scanning probe microscopy(SPM),scanning thermal microscopy(STh M)is able to collect thermophysical characteristics of the microscopic domain with high spatial *** from its development history,this review introduces the operation mechanism of the instrument in detail,including working principles,thermal probes,quantitative study,and *** the core principle of STh M,the heat transfer mechanism section is discussed ***,the emerging technologies based on the STh M platform are clearly reviewed and corresponding examples are presented in ***,the current challenges and future opportunities of STh M are discussed.

关键词： micro/nanoscale thermal mapping scanning thermal microscopy interfacial heat transfer thermoelectrics

Point-cloud segmentation of individual trees in complex natural forest scenes based on a trunk-growth method

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Journal of Forestry Research 2021年第6期32卷 2403-2414页

作者： Qianwei liu Weifeng Ma Jianpeng Zhang yicheng liu Dongfan Xu Jinliang Wang Faculty of Geography Yunnan Normal UniversityKunming 650092YunnanPeople’s Republic of China Key Laboratory of Resources and Environmental Remote Sensing for Universities in Yunnan Kunming 650500YunnanPeople’s Republic of China Center for Geospatial Information Engineering and Technology of Yunnan Province Kunming 650500YunnanPeople’s Republic of China Forestry College Southwest Forestry UniversityKunming 650224YunnanPeople’s Republic of China

Forest resource management and ecological assessment have been recently supported by emerging *** laser scanning(TLS)is one that can be quickly and accurately used to obtain three-dimensional forest information,and create good representations of forest vertical *** data can be exploited for highly significant tasks,particularly the segmentation and information extraction for individual ***,the existing single-tree segmentation methods suffer from low segmentation accuracy and poor robustness,and hence do not lead to satisfactory results for natural forests in complex *** this paper,we propose a trunk-growth(TG)method for single-tree point-cloud segmentation,and apply this method to the natural forest scenes of Shangri-La City in Northwest Yunnan,***,the point normal vector and its Z-axis component are used as trunk-growth ***,the points surrounding the trunk are searched to account for ***,the nearest distributed branch and leaf points are used to complete the individual tree *** results show that the TG method can effectively segment individual trees with an average F-score of *** proposed method applies to many types of trees with various growth shapes,and can effectively identify shrubs and herbs in complex scenes of natural *** promising outcomes of the TG method demonstrate the key advantages of combining plant morphology theory and LiDAR technology for advancing and optimizing forestry systems.

关键词： Terrestrial laser scanning Point-cloud Northwest Yunnan Natural forests Single-tree segmentation Trunk-growth

Stochastic Chebyshev-Picard Iteration Method for Nonlinear Differential Equations with Random Inputs

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Communications in Mathematical Research 2024年第3期40卷 275-312页

作者： Lingling Ma yicheng liu Department of Mathematics National University of Defense TechnologyChangsha 410003China School of Mathematics and Statistics Hunan First Normal UniversityChangsha 410205China

This work presents a stochastic Chebyshev-Picard iteration method to efficiently solve nonlinear differential equations with random *** the nonlinear problem involves uncertainty,we need to characterize the uncer-tainty by using a few random *** nonlinear stochastic problems require solving the nonlinear system for a large number of samples in the stochastic space to quantify the statistics of the system of response and explore the uncertainty *** computational cost is very *** overcome the difficulty,a low rank approximation is introduced to the solution of the corresponding nonlinear problem and admits a variable-separation form in terms of stochastic basis functions and deterministic basis *** it-eration is performed at each enrichment *** basis functions are model-oriented and involve offline *** efficiently identify the stochastic basis functions,we utilize the greedy algorithm to select some optimal *** the modified Chebyshev-Picard iteration method is used to solve the nonlinear system at the selected optimal samples,the solutions of which are used to train the deterministic basis *** the deterministic basis functions,we can obtain the corresponding stochastic basis functions by solv-ing linear differential *** computation of the stochastic Chebyshev-Picard method decomposes into an offline phase and an online *** is very desirable for scientific *** examples are presented to illustrate the efficacy of the proposed method for different nonlinear differential equations.

关键词： Nonlinear ordinary differential equation Chebyshev-Picard iteration me-thod variable-separation method random inputs

IMPULSIVE BOUNDARY VALUE PROBLEMS FOR STURM-LIOUVILLE TYPE DIFFERENTIAL INCLUSIONS

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Journal of Systems Science & Complexity 2007年第3期20卷 370-380页

作者： yicheng liu Jun WU Zhixiang LI Department of Mathematics and Systems Science College of Science National University of Defense Technology Changsha 410073 China. College of Mathematics and Computer Science Changsha University of Science Technology Changsha 410076 China.

In this paper, the authors investigate the existence of solutions of impulsive boundary value problems for Sturm-Liouville type differential inclusions which admit non-convex-valued multifunctions on right hand side. Two results under weaker conditions are presented. The methods rely on a fixed point theorem for contraction multi-valued maps due to Covitz and Nadler and Schaefer＇s fixed point theorem combined with lower semi-continuous multi-valued operators with decomposable values.

关键词： Boundary value problems contraction multi-valued map impulsive differential inclusions,measurable selection.

Dynamics Analysis for a Hierarchical System with Nonlinear Cut-Off Interaction and FreeWill

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Analysis in Theory and Applications 2024年第1期40卷 38-56页

作者： Ziyu Zhao yicheng liu Xiao Wang College of Liberal Arts and Science National University of Defense TechnologyChangshaHunan 410073China

Noting that the particles communicate with each other within aﬁnite dis-tance,in the paper,we investigate the hierarchical model with free will and cut-off function(linear or nonlinear).As our observation,the cut-off size r is a sensitive coef-ﬁcient to achieve theﬂocking *** we will use energy function to achieve some sufﬁcient conditions to achieve aﬂ*** free-will represents the tendency of the particle itself to *** will either facilitate or prevent cluster *** numerical simulations will validate our conclusions.

关键词： Motsch-Tadmor model hierarchical structure free will ﬂocking behavior

Efficient and Explicit Fourier Modal Method for Ultrathin Metallic Gratings

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Chinese Journal of Electronics 2022年第6期31卷 1155-1160页

作者： LI Jie SHI Lihua JIN Xin ZHANG Qi RAN Yuzhou LEI Qi MA Yao liu yicheng XIAO Jie WANG Jianbao National Key Laboratory on Electromagnetic Environment Effects and Electro-optical Engineering Army Engineering University of PLA Dongbei University of Finance and Economics National Innovation Institute of Defense Technology Academy of Military Sciences Unit 31007 of the PLA Cangxi School Education Bureau of Xinhua County

The solution of large matrix eigenvalues and complex linear equations limits the Fourier modal method(FMM) application in ultrathin metallic gratings(UMG) analysis. This paper proposes an efficient and explicit FMM method for analyzing UMG. The proposed method avoids solving complex linear equations and eigenvalues of eigenmatrix in the conventional method by simplifying the implementation equations. Two numerical examples then verify the reliability of the proposed method compared with CST simulations and the conventional method. The proposed method is proven efficient in decreasing the CPU time by over 80% and demanding significantly less memory.

关键词： Fourier modal method application implementation equations efficient FMM method matrix eigenvalues explicit FMM method diffraction gratings Fourier transform optics ultrathin metallic grating analysis eigenvalues and eigenfunctions eigenmatrix CPU time complex linear equations matrix algebra

PERIODIC CHARACTER OF A DIFFERENCE EQUATION WITH MAXIMUM

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Annals of Differential Equations 2005年第3期21卷 362-365页

作者： liu yicheng Li Zhixiang Dept. of Math. and System Science Science School National University of Defence Technology Changsha 410073

We study the periodicity of the positive solutions of a class of difference equations with maximum. We prove that every positive solutions of these equations are eventually periodic.

关键词： periodic solutions nonlinear difference equation

Demand Analysis and Management Suggestion:Sharing Epidemiological Data Among Medical Institutions in Megacities for Epidemic Prevention and Control

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Journal of Shanghai Jiaotong university(Science) 2020年第2期25卷 137-139页

作者： CAI Qinyi MI Yiqun CHU Zhaowu ZHENG Yuanyi CHEN Fang liu yicheng The Sixth People's Hospital Affiliated to Shanghai Jiao Tong University Shanghai 200233China Shanghai Big Data Center Shanghai 200072China

During the prevention of coronavirus disease 2019(COVID-19),epidemiological data is essential for controlling the source of infection,cutting off the route of transmission,and protecting vulnerable *** Law of the People's Republic of China on Prevention and Treatment of Infectious Diseases and other related regulations,medical institutions have been authorized to collect the detailed information of patients,while it is still a formidable task in megacities because of the significant patient mobility and the existing information sharing *** a smart city which strengthens precise epidemic prevention and control,Shanghai has established a multi-department platform named"one-net management"on dynamic information *** sharing epidemiological data with medical institutions under a safe environment,we believe that the ability to prevent and control epidemics among medical institutions will be effectively and comprehensively improved.

关键词： epidemic prevention and control big data sharing medical institutions megacities