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Multi-UAV Cooperative Hunting in Cluttered Environments Considering Downwash E®ects

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Guidance, Navigation and Control 2023年第1期3卷 61-84页

作者： Shichen Fan Hugh H.-t.liu Institute for Aerospace Studies University of toronto 4925 Du®erin Street North YorkOntarioCanada M3H 5T6

this paper presents a novel solution to the three-dimensional (3D) cooperative hunting ofmultiple drones that deals with surrounding a target simultaneously while navigating aroundobstacles in the cluttered dynamic 3D environment. Meanwhile, drones avoid the air°owdownwash force created by the spinning propellers on unmanned aerial vehicles (UAVs) andtheir e®ect on the other UAVs. this solution consists of a 3D Simultaneous Encirclementstrategy, the cooperative hunting objective with a novel revised particle swarm optimization(PSO*) path planning algorithm, a °ocking theory-inspired obstacle avoidance algorithm, and acascade PI controller. Simulation results with varying conditions were carried out to validatethe e®ectiveness of the proposed solution by successfully taking care of the downwash e®ects,and having multiple hunter UAVs hunt and encircle a moving or stationary target in a dynamicor static obstacle-rich cluttered environment.

关键词： Cooperative hunting downwash e®ect UAS.

Adaptive Modeling for Downwash E®ects in Multi-UAV Path Planning

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Guidance, Navigation and Control 2021年第4期1卷 83-98页

作者： Chih-Chun Chen Hugh H.-t.liu Institute for Aerospace Studies University of Toronto4925 Du®erin StreetNorth YorkOntario M3H 5T6Canada

this pape developa a novel mettad to model the air flow downwash faree ganated by the quadrotor un manmed arial vehiele(UAV)and itsefket on the neigh boring *** UAV shaped by a wirtual stracture for oollision-tree path plan *** shape is modified from a standard apberical body to a prapased adaptive eylinder to optimine the path planning while mani mloing the dowuwash *** eylinder beight varies based on the UAV dzumstanae and the paedieted downwash ***,the downwash model can aid in the eylinder beightextreme valae appointment.A flock-basedpath planning algorithm is invastigated in this study to ompare the spberical UAV shape model with the prapased eylindrical UAV shape *** UAV with the adaptve eylindrical model is simulated and verified via Gaseho and Robat Operating System(ROS)simulation platfarm.

关键词： Dowm waah efket adaptive height floeking path planming

Redefining Human Vitamin D Sufficiency:Back to the Basics

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Bone Research 2013年第1期1卷 2-10页

作者： John S.Adams Jonathan Ramin Brandon Rafison Charles Windon Annika Windon Philip t.liu Orthopaedic Hospital Research Center UCLA-Orthopaedic Hospital Department of Orthopaedic SurgeryDavid Geffen School of MedicineUCLA Department of Molecular Cell and Developmental BiologyDivision of Life SciencesCollege of Letters and ScienceUCLA

the role of the endocrine vitamin D pathway in regulating the serum calcium concentration in man is well described. In the presence of a low serum calcium level, the vitamin D metabolic pathway is called upon to produce more of the active vitamin D hormone, 1, 25-dihydroxyvitamin D （1, 25D）, via up-regulation of the CYP27b1-hydroxylase activity in the kidney. the consequence is mobilization of skeletal calcium stores to return the circulating calcium level back to the normal range. On the other hand, when the serum calcium level increases, endocrine forces move to suppress renal 1, 25D production and squelch bone resorption. It is now known that vitamin D metabolites also operate in an autocrine, paracrine and intracrine mode to control vitamin D receptor-directed biological responses at the tissue level. Because the metabolism and action of vitamin D occurs at the tissue level in this situation, use of circulating vitamin D metabolites and biomarkers to ascertain the local action of the vitamin D pathway is often misleading. this mini-review seeks to compare and contrast the operation of the vitamin D pathway at the endocrine and tissue level.

关键词： metabolism endocrine autocrine hormone biomarkers

Effect of Long-term thermal Exposure on Microstructure and Stress Rupture Properties of GH3535 Superalloy

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Journal of Materials Science & technology 2015年第3期31卷 269-279页

作者： t.liu J.S.Dong L.Wang Z.J.Li X.t.Zhou L.H.Lou J.Zhang School of Materials Science and Engineering Dalian University of Technology Institute of Metal Research Chinese Academy of Sciences Shanghai Institute of Applied Physics Chinese Academy of Sciences Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

the evolution of microstructure and the stress rupture properties of long term thermally exposed GH3535 alloy have been investigated. It was found that M6 C carbides presented in the solid solution heat treated samples. During long term thermal exposure at 700 C, fine M12 C carbides precipitated preferentially at grain boundaries. these carbides coexisted with the pre-exiting M6 C. the stress rupture life of700 C/1000 h exposed sample under creep testing at 650 C/324 MPa is 93 h. It is much longer than that of the solid solution samples. No noticeable changes could be detected in both the microstructure and stress rupture lives when the samples were exposed for time longer than 1000 h M12 C carbides were found to be beneficial to the creep properties. the cracks initiated at the interface of M6 C carbides and matrix, which led to a lower creep rupture life.

关键词： GH3535 superalloy Long term thermal exposure Micro

An XAFS measurement of copper thin film by a simple detector in total—electron—yield mode

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同步辐射装置用户科技论文集 2000年第1期 22-27页

作者： t.liu Y.N.Xie 等

Short Notes ON tHE γ—ε tRANSFORMAtION BELOW tHE NEEL tEMPERAtURE IN Fe—Mn—Si ALLOYS

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同步辐射装置用户科技论文集 1999年第1期 26-29页

作者： t.liu Z.t.ZHAO 等 BeijingSynchrotronRadiationFacility InstituteofHighEnergyPhysicsChineseAcademyofSciencesBeijing100039P.R.China DepartmentofMaterialsPhysics UniversityofScience＆TechnologyBeijing

there are two tpyes of phase transformations in Fe-Mn and Fe-Mn-Si alloys when the temperature is decreased,γ(fcc)→ε(hcp) martensitic transformation(Mt) and paramagnetic-antiferromagnetic transition (AMt) of γ *** the thermodynamic point of view,the former usually appears in a slightly higher temperature range than the latter because if is generally accepted that the magnetic tansition has a suppressing effect on the thermally induced ε martensite(Sato et al.,1984.,Bogachev and Zvigintzeva,1976;Murakami et al.,1987:Yang et al.,1992) Gartstein and Robinkin(1979) even thought that the γ-ε transformation should be terminated below Neel temperature(tN) due to the decrease of free energy arising from the AMt of γ ***,some experimental results hae indicated the formation of ε phase below t(Li and Wayman,1994:Fujimori.1966).In the present *** behavor of γ-ε transformation below tN was furtherinvestigated by clectrical resistance measurements.

关键词：相变 Fe-Mn-Si合金 γ(fcc)-ε(hcp)

Incorporating Magnetic Hysteresis of Molecular Nanowire and Anisotropic thermal-Expansion-Induced Hysteretic Magnetic transition

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Incorporating Magnetic Hysteresis of Molecular Nanowire and ...

thermal induced spin crossover behavior of two dinuclear Fe(Ⅱ) complexes

第七届全国物理无机化学学术会议

作者： t.liu L.Zhao State Key Laboratory of Fine Chemicals Dalian University of Technology

Magnetic bistable materials can potentially be used as memory and switch *** multifaceted materials by incorporating two or more hysteretic magnetic transitions that respond to different perturbations into a single material is *** this study,inorganic W-CoN-Fe chains were linked by ditopic organic ligands to a 3D framework,which exhibited both thermal hysteresis and

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Thermal induced spin crossover behavior of two dinuclear Fe(...

基于MRI影像组学特征识别结核性脑膜炎基底池肉眼不可见改变:一项多中心初步研究

第七届全国物理无机化学学术会议

作者： J.L.Wang Q.liu Q.Wu t.liu State Key Laboratory of Fine Chemicals Dalian University of Technology

two dinuclear Fe(Ⅱ)complexes FeL(NCS)×2DMF×2HO(1)and FeL(NCSe)4×2DMF×2HO(2)have been designed and prepared based on ligand 1-naphthylimino-1,2,4-triazole(L).Single-crystal structural analyses at 298 K identified that the dinuclear complex contains two iron(II)ions in the high spin(HS)state for 1 and *** Fe(Ⅱ)ions in 1 and 2 were low spin(LS)state at 90 K by comparison with the

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国际医学放射学杂志 2023年第1期46卷 123-124页

作者： Q.Ma Y.Yi t.liu X.Wen F.Shan F.Feng 张谍

摘要目的开发和探讨基于多中心MRI数据的影像组学指标,旨在识别结核性脑膜炎(tBM)病人基底池肉眼不可见的病变。方法回顾性研究纳入来自3家中国医院的184

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