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Formation flight of fixed-wing UAV swarms:A group-based hierarchical approach

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Chinese Journal of Aeronautics 2021年第2期34卷 504-515页

作者： hao chen Xiangke WANG Lincheng SHEN Yirui CONG College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China

This paper investigates a formation control problem of fixed-wing Unmanned Aerial Vehicle(UAV) swarms. A group-based hierarchical architecture is established among the UAVs, which decomposes all the UAVs into several distinct and non-overlapping groups. In each group, the UAVs form hierarchies with one UAV selected as the group leader. All group leaders execute coordinated path following to cooperatively handle the mission process among different groups, and the remaining followers track their direct leaders to achieve the inner-group coordination. More specifically, for a group leader, a virtual target moving along its desired path is assigned for the UAV, and an updating law is proposed to coordinate all the group leaders’ virtual targets;for a follower UAV, the distributed leader-following formation control law is proposed to make the follower’s heading angle coincide with its direct leader, while keeping the desired relative position with respect to its direct leader. The proposed control law guarantees the globally asymptotic stability of the whole closed-loop swarm system under the control input constraints of fixed-wing UAVs. Theoretical proofs and numerical simulations are provided, which corroborate the effectiveness of the proposed method.

关键词： Control input constraints Coordinated path following Formation control Leader-following control Unmanned aerial vehicles swarms

User-oriented data acquisition chain task planningalgorithm for operationally responsive space satellite

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Journal of Systems Engineering and Electronics 2016年第5期27卷 1028-1039页

作者： hao chen Jun Li Ning Jing Jun Li College of Electronic Science and Engineering National University of Defense TechnologyChangsha 410073China Unit 61726 of the PLA Wuhan 430074China

With the development of operationally responsive space（ORS） and on-board processing techniques, the end users canreceive the observation data from the ORS satellite directly. Tosatisfy the demand for reducing the requirements-tasking-effectscycle from one day to hours, the various resources of the wholedata acquisition chain （including satellites, ground stations, dataprocessing centers, users, etc.） should be taken into an overallconsideration, and the traditional batch task planning mode shouldbe transformed into the user-oriented task planning mode. Consideringthere are many approaches for data acquisition due tothe new techniques of ORS satellite, the data acquisition chaintask planning problem for ORS satellite can be seen as the multimodalroute planning problem. Thereby, a framework is presentedusing label-constrained shortest path technique with the conflictresolution. To apply this framework to solve the ORS satellite taskplanning problem, the preprocessing and the conflict resolutionstrategies are discussed in detail. Based on the above work, theuser-oriented data acquisition chain task planning algorithm forORS satellite is proposed. The exact solution can be obtainedin polynomial time using the proposed algorithm. The simulationexperiments validate the feasibility and the adaptability of the proposedapproach.

关键词： operationally responsive space (ORS) remote sensing,scheduling multi-modal route planning shortest path computationalcomplexity.

Study on self-healing and corrosion resistance behaviors of functionalized carbon dot-intercalated graphene-based waterborne epoxy coating

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Journal of Materials Science & Technology 2021年第8期67卷 226-236页

作者： Yuwei Ye hao chen Yangjun Zou Haichao Zhao Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China Ningbo Institute of Materials Technology&Engineering Chinese Academy of SaencesNingbo 315201China

Functionalized carbon dots(CDs)obtained from citric acid derivative were selected as intercalatorto modify graphene and then dispersed into epoxy matrix to prepare CDs modified graphene/epoxy(CDs-G/EP)***,their microstructure,self-healing and corro sion resistance behaviors were analyzed *** characterizations indicated the formation of"π-π"interaction between functionalized carbon dots and *** observation,the dispersion and interface compatibility of graphene were greatly enhanced by *** change rules of electrochemistry results implied that the addition of 0.5 wt.%CDs-G in EP coating(CDs-G0.5%/EP)demonstrated a superior protective property on steel,which was attributed to the physical barrier of highly dispersed graphene and the self-healing ability of *** 50 days immersion,the oxygen permeability coefficient and water absorption of CDs-G0.5%/EP coating were only 4.27×10^(-13)cm^(3)cm cm^(-2)s^(-1)Pa^(-1) and 4.4%,respectively.

关键词： Functionalized carbon dots Corrosion Graphene Self-healing

Equivalent low-order angular flux nonlinear finite difference equation of MOC transport calculation

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Nuclear Science and Techniques 2020年第12期31卷 139-151页

作者： Li-Xun Liu chen hao Yun-Lin Xu Fundamental Science On Nuclear Safety and Simulation Technology Laboratory Harbin Engineering UniversityHarbin 150001China Institute of Nuclear and New Energy Technology(INET) Tsinghua UniversityBeijing 100084China Purdue University West LafayetteIN 47907USA

The key issue in accelerating method of characteristics(MOC)transport calculations is in obtaining a completely equivalent low-order neutron transport or diffusion ***,an equivalent low-order angular flux nonlinear finite difference equation is proposed for MOC transport *** method comprises three essential features:(1)the even parity discrete ordinates method is used to build a low-order angular flux nonlinear finite difference equation,and different boundary condition treatments are proposed;(2)two new defined factors,i.e.,the even parity discontinuity factor and odd parity discontinuity factor,are strictly defined to achieve equivalence between the low-order angular flux nonlinear finite difference method and MOC transport calculation;(3)the energy group and angle are decoupled to construct a symmetric linear system that is much easier to *** equivalence of this low-order angular flux nonlinear finite difference equation is analyzed for two-dimensional(2D)pin,2D assembly,and 2D C5G7 benchmark *** results demonstrate that a low-order angular flux nonlinear finite difference equation that is completely equivalent to the pin-resolved transport equation is established.

关键词： Angular flux Equivalence Even parity discrete ordinates method Nonlinear finite difference

Some results on the algebraic immunity of Boolean functions

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The Journal of China Universities of Posts and Telecommunications 2011年第2期18卷 102-105页

作者： XU Li-qing chen hao Software Engineering Institute East Normal University Shanghai 200062 China

From the motivation of algebraic attacks on stream and block ciphers,the concept of algebraic immunity（AI） of a Boolean function was introduced and studied *** algebraic immunity is a necessary condition for resisting algebraic *** this paper,we give some lower bounds on the algebraic immunity of Boolean *** results are applied to give lower bounds on the AI of symmetric Boolean functions and rotation symmetric Boolean *** balanced rotation symmetric Boolean functions with their AI near the maximum possible value「n/2」are constructed.

关键词： algebraic attack Boolean function AI symmetric Boolean function rotation symmetric Boolean function

A theoretical study on the unsteady aerothermodynamics for attached flow models

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Science China(Physics,Mechanics & Astronomy) 2010年第8期53卷 1505-1514页

作者： chen hao BAO Lin TONG BingGang Graduate University of the Chinese Academy of Sciences Beijing 100049China

The principle of the unsteady aerothermodynamics was theoretically investigated for the attached flow. Firstly, two simplified models with analytic solutions to the N-S equations were selected for the research, namely the compressible unsteady flows on the infinite flat plate with both time-varying wall velocity and time-varying wall temperature boundary conditions. The unsteady temperature field and the unsteady wall heat flux (heat flow) were analytically solved for the second model. Then, the interaction characteristic of the unsteady temperature field and the unsteady velocity field in the simplified models and the effects of the interaction on the transient wall heat transfer were studied by these two analytic solutions. The unsteady heat flux, which is governed by the energy equation, is directly related to the unsteady compression work and viscous dissipation which originates from the velocity field governed by the momentum equation. The main parameters and their roles in how the unsteady velocity field affects the unsteady heat flux were discussed for the simplified models. Lastly, the similarity criteria of the unsteady aerothermodynamics were derived based on the compressible boundary layer equations. Along with the Strouhal number Stu, the unsteadiness criterion of the velocity field, StT number, the unsteadiness criterion of the temperature field was proposed for the first time. Different from the traditional method used in unsteady aerodynamics which measures the flow unsteadiness only by the Stu number, present results show that the flow unsteadiness in unsteady aerothermodynamics should be comprehensively estimated by comparing the relative magnitudes of the temperature field unsteadiness criterion StT number with the coefficients of other terms in the dimensionless energy equation.

关键词： unsteady aerothermodynamics transient heat transfer similarity criterion

Universal order-parameter and quantum phase transition for two-dimensional q-state quantum Potts model

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Chinese Physics B 2022年第7期31卷 163-168页

作者： Yan-Wei Dai Sheng-hao Li Xi-hao chen Centre for Modern Physics and Department of Physics Chongqing UniversityChongqing 400044China Chongqing Vocational Institute of Engineering Chongqing 402260China Research Institute for New Materials and Technology Chongqing University of Arts and SciencesChongqing 400000China

We investigate quantum phase transitions for q-state quantum Potts models(q=2,3,4)on a square lattice and for the Ising model on a honeycomb lattice by using the infinite projected entangled-pair state algorithm with a simplified updating *** extend the universal order parameter to a two-dimensional lattice system,which allows us to explore quantum phase transitions with symmetry-broken order for any translation-invariant quantum lattice system of the symmetry group *** universal order parameter is zero in the symmetric phase,and it ranges from zero to unity in the symmetry-broken *** ground-state fidelity per lattice site is computed,and a pinch point is identified on the fidelity surface near the critical *** results offer another example highlighting the connection between(i)critical points for a quantum many-body system undergoing a quantum phase-transition and(ii)pinch points on a fidelity *** addition,we discuss three quantum coherence measures:the quantum Jensen–Shannon divergence,the relative entropy of coherence,and the l1norm of coherence,which are singular at the critical point,thereby identifying quantum phase transitions.

关键词： quantum phase transitions universal order parameter fidelity

Wind power forecasting based on outlier smooth transition autoregressive GARCH model

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Journal of Modern Power Systems and Clean Energy 2018年第3期6卷 532-539页

作者： hao chen Fangxing LI Yurong WANG State Grid Jiangsu Electric Power Company Department of Electrical Engineering and Computer Science University of Tennessee School of Electrical Engineering Southeast University

The impacts of outlying shocks on wind power time series are explored by considering the outlier effect in the volatility of wind power time series. A novel short term wind power forecasting method based on outlier smooth transition autoregressive(OSTAR) structure is advanced, then, combined with the generalized autoregressive conditional heteroskedasticity(GARCH) model, the OSTAR-GARCH model is proposed for wind power forecasting. The proposed model is further generalized to be with fat-tail ***, the mechanisms of regimes against different magnitude of shocks are investigated owing to the outlier effect parameters in the proposed models. Furthermore, the outlier effect is depicted by news impact curve(NIC) and a novel proposed regime switching index(RSI). Case studies based on practical data validate the feasibility of the proposed wind power forecasting method. From the forecast performance comparison of the OSTAR-GARCH models, the OSTAR-GARCH model with fat-tail distribution proves to be promising for wind power forecasting.

关键词： OSTAR-GARCH model Regime switching index(RSI) Outlier effect Wind power forecasting

Vectorial Resilient PC(l) of Order k Boolean Functions from AG-Codes

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Chinese Annals of Mathematics,Series B 2011年第1期32卷 99-104页

作者： hao chen Liang MA Jianhua LI Software Engineering Institute East China Normal University Shanghai 200062 China Institute of Systems Science University of Shanghai for Science and Technology Shanghai 200093 China Department of Electronic Engineering Shanghai Jiaotong University Shanghai 200030 China

Propagation criteria and resiliency of vectorial Boolean functions are important for cryptographic purpose(see [1-4,7,8,10,11,16]).Kurosawa,Stoh [8] and Carlet [1] gave a construction of Boolean functions satisfying PC(l) of order k from binary linear or nonlinear *** this paper,the algebraic-geometric codes over GF(2m) are used to modify the Carlet and Kurosawa-Satoh's construction for giving vectorial resilient Boolean functions satisfying PC(l) of order k *** new construction is compared with previously known results.

关键词： Cryptography Boolean function Algebraic-geometric code