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Design and implementation of a leader-follower cooperative control system for unmanned h.licopters

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控制理论与应用（英文版） 2010年第1期8卷 61-68页

作者： ben YUN ben M. Ch.N Kai Yew LUM Tong h. LEE Department of Electrical & Computer Engineering National University of Singapore Singapore 117576 Temasek Laboratories National University of Singapore Singapore 117508

In th.s paper, we present a full sch.me for th. cooperative control of multiple unmanned aerial veh.cle （UAV） h.licopters. We adopt th. leader-follower pattern to maintain a fixed geometrical formation wh.le navigating th. UAVs following certain trajectories. More specifically, th. leader is commanded to fly on some predefined trajectories, and each.follower is controlled to maintain its position in formation using th. measurement of its inertial position and th. information of th. leader position and velocity, obtained th.ough.a wireless modem. More specifications are made for multiple UAV formation fligh.. In order to avoid possible collisions of UAV h.licopters in th. actual formation fligh. test, a collision avoidance sch.me based on some predefined alert zones and protected zones is employed. Simulations and experimental results are presented to verify our design.

关键词： Unmanned aerialveh.cles Cooperative control Fligh. formation Collision avoidance

Performance Improved of a Lime and h.mp-Based Concrete th.ough.th. Addition of Metakaolin

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Fluid Dynamics & Materials Processing 2023年第5期19卷 1091-1113页

作者： Suzanne Dah.r Amar benazzouk h.ïkel ben h.med Th.erry Langlet Universitéde Picardie Jules Verne Avenue des Facultés Amiens80025France

Th.s work describes in detail th. experimental investigation of th. ph.sico-mech.nical properties of nonstructural h.mp concrete(usually used as insulating wall material)wh.n th. Air-lime based Tradial PF70 binder is partially replaced using *** objective is to reduce th. amount of free Ca2+ions in th. binder as th.se are responsible for th. degradation of vegetables particles and can th.refore induce a loss of mech.nical *** order to assess th. effectiveness of pozzolanic reaction,amounts of 0%,10%,and 20%*** Air-lime binder were replaced by th. Metakaolin material,wh.le testing th. mech.nical properties of concrete specimens containing 200%and 300%of h.mp *** SEM and EDX analysis,a tigh. relationsh.p h.s been found to exist between th. Metakaolin content and ph.sical-mech.nical properties of *** pozzolanic reaction consumes calcium h.droxide from binder to produce h.drated Calcium Silicates(C-S-h.and in turn,th.s leads to a decrease in th. ph.value of th. pore solution wh.ch.is th. main factor responsible for h.mp particle degradation.

关键词： Agro-sourced materials h.mp particles tradical PF70 binder metakaolin pozzolanic products mech.nical properties deformability particle mineralisation SEM and EDX analyses

A MATLAB toolkit for composite nonlinear feedback control–improving transient response in tracking control

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控制理论与应用（英文版） 2010年第3期8卷 271-279页

作者： Guoyang Ch.NG ben M. Ch.N Kemao PENG Tong h. LEE College of Electrical Engineering and Automation Fuzhou University Fuzhou Fujian 350108 China Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Temasek Laboratories National University of Singapore Singapore 117508

We present in th.s article a MATLAB toolkit with.a user-friendly graph.cal interface for composite nonlinear feedback control system design. Th. toolkit can be utilized to design a fast and smooth.tracking controller for a class of linear systems and nonlinear systems with.actuator and oth.r nonlinearities as well as with.external disturbances. Th. parameters of th. controller can be tuned easily on th. user panel or autotuned by th. toolkit. Th. toolkit is capable of displaying both.time-domain and frequency-domain responses on its main panel and generating th.ee different types of con- trol laws, namely, th. state feedback, th. full-order measurement feedback and th. reduced-order measurement feedback controllers. Th. usage and design procedure of th. toolkit are illustrated by practical examples on a rotational/translational actuator （RTAC） system and a h.rd disk drive servo system. Th. toolkit can be utilized to design servo systems th.t deal with.point-and-sh.ot fast targeting.

关键词： Nonlinear control Actuator saturation Tracking control Computer-aided design

Development of a vision-based ground target detection and tracking system for a small unmanned h.licopter

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作者： ben h. Winters.

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Science in Ch.na(Series F) 2009年第11期52卷 2201-2215页

作者： LUM Kai-Yew Ch.N ben M. LEE Tong h. Department of Electrical & Computer Engineering National University of Singapore

It is undoubted th.t th. latest trend in th. unmanned aerial veh.cles （UAVs） community is towards vision-based unmanned small-scale h.licopter, utilizing th. maneuvering capabilities of th. h.licopter and th. rich.information of visual sensors, in order to arrive at a versatile platform for a variety of applications such.as navigation, surveillance, tracking, etc. In th.s paper, we present th. development of a vision-based ground target detection and tracking system for a small UAV h.licopter. More specifically, we propose a real-time vision algorith., based on moment invariants and two-stage pattern recognition, to ach.eve automatic ground target detection. In th. proposed algorith., th. key geometry features of th. target are extracted to detect and identify th. target. Simultaneously, a Kalman filter is used to estimate and predict th. position of th. target, referred to as dynamic features, based on its motion model. Th.se dynamic features are th.n combined with.geometry features to identify th. target in th. second-stage of pattern recognition, wh.n geometry features of th. target ch.nge significantly due to noise and disturbance in th. environment. Once th. target is identified, an automatic control sch.me is utilized to control th. pan/tilt visual mech.nism mounted on th. h.licopter such.th.t th. identified target is to be tracked at th. center of th. captured images. Experimental results based on images captured by th. small-scale unmanned h.licopter, Sh.Lion, in actual fligh. tests demonstrate th. effectiveness and robustness of th. overall system.

关键词： target tracking unmanned aerial veh.cle image processing pattern recognition Kalman filtering

Natural Convection of a Power-Law Nanofluid in a Square Cavity with.a Vertical Fin

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Fluid Dynamics & Materials Processing 2024年第9期20卷 2091-2108页

作者： Amira M’h.dbi Moh.mmed El Ganaoui h.ïkel ben h.med Amenallah.Guizani Kh.lid Ch.aibi LERMAB Department of Transition and Energy Efficiency ProfessionsIUT H Poincaréde LongwyUniversity of LorraineLongwy54400France LPT Center for Energy Research and Technologies(Borj Cedria2084)University of Tunis El ManarTunis1068Tunisia LTI Department of Mechanical Engineering and ProductionIUTUniversity of Picardie Jules-VerneAmiens80025France

Th. beh.vior of non-Newtonian power-law nanofluids under free convection h.at transfer conditions in a cooled square enclosure equipped with.a h.ated fin is investigated *** particular,th. impact of nanofluids,composed of water and Al_(2)O_(3),TiO_(2),and Cu nanoparticles,on h.at transfer enh.ncement is *** aim of th.s research.is also to analyze th. influence of different parameters,including th. Rayleigh.number(Ra=10^(4)-10^(6)),nanoparticle volume fraction(φ=0%-20%),non-Newtonian power-law indexes(n=0.6-1.4),and fin dimensions(Ar=0.3,0.5,and 0.7).Streamlines and isoth.rms are used to depict flow and related h.at transfer *** indicate th.t th.rmal performance improves with.increasing Rayleigh.number,regardless of th. nanoparticle type or nanofluid rh.ological *** suggests th.t th. buoyancy force h.s a significant impact on h.at transfer,particularly near th. h.at *** Nusselt number is more sensitive to variations in Cu nanoparticle volume fractions compared to Al₂O₃and TiO₂.Moreover,th. average Nusselt numbers for power-law nanofluids with.n1)are greater(smaller)th.n for Newtonian fluids due to th. decrease(increase)in viscosity with.increasing(decreasing)sh.ar rate,at th. same values of Rayleigh.number Ra owing to th. amplification(attenuation)of th. convective ***,th. most substantial enh.ncement is observed with.Cu-water sh.ar-th.nning nanofluid,wh.re th. Nusselt number increases by 136%wh.n ch.nging from Newtonian to sh.ar th.nning beh.vior and by 154.9%wh.n adding 16%nanoparticle volume ***,an even larger increase of 57%in th. average Nusselt number is obtained on increasing th. fin length.from 0.3 to 0.7.

关键词： h.at transfer nanofluid non-Newtonian fluid natural convection

Optimal Deployment of Mobile Sensors for Target Tracking in 2D and 3D Spaces

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IEEE/CAA Journal of Automatica Sinica 2014年第1期1卷 24-30页

作者： Sh.yu Zh.o ben M Ch.n Tong h.Lee th. Graduate Sch.ol for Integrative Sciences and Engineering National University of Singapore th. Department of Electrica and Computer Engineering National University of Singapore

Th.s paper proposes a control strategy to autonomously deploy optimal placements of range-only mobile sensors in 2D and 3D spaces. Based on artificial potential approach.s, th. control strategy is designed to minimize th. intersensor and external potentials. Th. inter-sensor potential is th. objective function for optimal sensor placements. A placement is optimal wh.n th. inter-sensor potential is minimized. Th. external potential is introduced to fulfill constraints on sensor trajectories. Since artificial potential approach.s can h.ndle various issues such.as obstacle avoidance and collision avoidance among sensors, th. proposed control strategy provides a flexible solution to practical autonomous optimal sensor deployment. Th. control strategy is applied to several optimal sensor deployment problems in 2D and 3D spaces. Simulation results illustrate h.w th. proposed control strategy can improve target tracking performance.

关键词： Optimal sensor placement mobile sensor net-work artificial potential target tracking

Discrete energy transport in collagen molecules

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Ch.nese Ph.sics B 2014年第9期23卷 544-548页

作者： Alain Mvogo Germain h.ben-Bolie Timoléon C.Kofané Laboratory of Bioph.sics Department of PhysicsFaculty of ScienceUniversity of Yaounde I Laboratory of Nuclear Ph.sics Department of PhysicsFaculty of ScienceUniversity of Yaounde I Centre d'Excellence Africain en Tech.ologies de l'Information et de la Communication University of Yaounde I Laboratory of Mech.nics Department of PhysicsFaculty of ScienceUniversity of Yaounde I

Th. modulational instability in th. th.ee coupled α-polypeptide ch.ins of a collagen molecule is investigated. Ch.osing symmetric and asymmetric solutions, and applying th. so-called rotating-wave approximation, we describe th. dynamics of th. system by th. discrete nonlinear Sch.odinger （DNLS） equation. Th. linear stability analysis of th. continuous wave solution is performed. Th. numerical simulations sh.w th. generation of trains of solitonic structures in th. lattice with.increasing amplitude as time progresses. Th. effect of damping and noise forces of th. ph.siological temperature （T = 300 K） introduces an erratic beh.vior to th. formed patterns, reinforcing th. idea th.t th. energy used in metabolic processes is confined to specific regions for efficiency.

关键词： modulational instability collagen molecules damping noise force

Dynamics of Soil and Grain Micronutrients as Affected by Long-Term Fertilization in an Aquic Inceptisol

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Pedosph.re 2010年第6期20卷 725-735页

作者： LI ben-Yin h.ANG Sh.o-Min WEI Ming-Bao h. L. Zh.NG Sh.N A-Lin XU Jian-Ming RUAN Xin-Ling Institute of Plant Nutrition Agricultural Resources and Environmental Sciences Henan Academy of Agricultural Sciences Zhengzhou 450002 (China) College of Environment and Natural Resources Zhejiang University Hangzhou 310058 (China) h.nan Provincial Key Lab of Surface and Interface Science Zhengzhou University of Light Industry Zhengzhou 450002 (China) Department of Plant and Soil Sciences Oklahoma State University Stillwater OK 74078 (USA) College of Environment and Planning Henan University Kaifeng 475000 (China)

Micronutrient status in soils can be affected by long-term fertilization and intensive cropping.A 19-year experiment (1990-2008) was carried out to investigate th. influence of different fertilization regimes on micronutrients in an Aquic Inceptisol and maize and wh.at grains in Zh.ngzh.u,*** results sh.wed th.t soil total Cu and Zn markedly declined after 19 years with.application of N fertilizer *** total Fe and Mn were significantly increased mainly due to atmosph.ric *** of P and organic fertilizer with.incorporation of straws resulted in dramatic increases in soil total Cu,Zn,Fe,and *** dieth.lenetriamine pentaacetic acid (DTPA)-extractable Cu in all treatments sh.rply decreased from initially 1.12 to about 0.8 mg kg -1 .Th. treatments with.organic fertilizer h.d th. h.gh.st soil DTPA-extractable Cu,Zn,Fe,and Mn after 19 years of cropping and fertilization,th.s demonstrating th. important role of organic fertilizer application in improving available micronutrient *** and Zn contents in wh.at grains in th. no-P treatments were significantly h.gh.r th.n th.se of th. treatments with.P *** addition,Fe and Mn contents in wh.at grains were positively correlated with.th.ir soil DTPA-extractable *** indicated th.t th. long-term application of organic fertilizer resulted in significant increases in soil total and available micronutrient concentrations and remarkable reduction in wh.at grain Cu and Zn contents,wh.ch.was due to h.gh.soil available P.

关键词： Cu organic fertilizer soil available P wh.at Zn