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Correlates of physical activity in fifth-grade students in Ho Chi Minh City,vietnam

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Sports Medicine and Health Science 2020年第1期2卷 33-37页

作者： Quyen G.To Danielle Gallegos dung v.do Hanh TM.Tran Kien G.To Lee Wharton Stewart G.Trost Appleton Institute School of HealthMedical and Applied SciencesCentral Queensland UniversityAustralia School of Exercise and Nutrition Sciences Queensland University of TechnologyBrisbaneAustralia School of Exercise and Nutrition Sciences Institute for Health and Biomedical Innovation at QLD Centre for Children's Health ResearchQueensland University of TechnologyBrisbaneAustralia Faculty of Public Health University of Medicine and Pharmacy at Ho Chi Minh CityViet Nam Nutrition Center Ho Chi Minh CityViet Nam

Studies investigating correlates of physical activity(PA)using objective PA measurements among primary schoolaged children are limited in Asia,particularly *** study examined psychosocial and environmental factors associated with PA among fifth-grade students in eight primary schools in Ho Chi Minh city,*** analyses showed that for every month increase in students’age,an increase of 66 steps/day(pvery unit increase in self-efficacy,perceived social influences,intention to be physically active,and parental support for PA,an increase of 220,200,522,and 117 steps/day(pvariable analysis,only intention and parental support for PA remained significant(pvariation in daily steps was explained by demographic characteristics and an additional 13%by psychosocial *** conclusion,intention to be physically active and parental support are important factors and should be considered when designing PA interventions in school/community-based settings.

关键词： Exercise Primary school Psychosocial Environmental Parental support

Nonlinear thermo-mechanical stability of eccentrically stiffened functionally graded material sandwich doubly curved shallow shells with general sigmoid law and power law according to third-order shear deformation theory

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Applied Mathematics and Mechanics(English Edition) 2017年第2期38卷 191-216页

作者： D.v.dung D.T.doNG Faculty of Mathematics Mechanics and Informatics Vietnam National University Hanoi 100000 Vietnam Faculty of Civil Engineering University of Transport Technology Hanoi 100000 Vietnam

In this paper, the nonlinear analysis of stability of functionally graded ma- terial （FGM） sandwich doubly curved shallow shells is studied under thermo-mechanical loads with material properties obeying the general sigmoid law and power law of four ma- terial models. Shells are reinforced by the FGM stiffeners and rest on elastic foundations. Theoretical formulations are derived by the third-order shear deformation theory （TSDT） with the von Karman-type nonlinearity taking into account the initial geometrical im- perfection and smeared stiffener technique. The explicit expressions for determining the critical buckling load and the post-buckling mechanical and thermal load-deflection curves are obtained by the Galerkin method. Two iterative algorithms are presented. The effects of the stiffeners, the thermal element, the distribution law of material, the initial imper- fection, the foundation, and the geometrical parameters on buckling and post-buckling of shells are investigated.

关键词： functionally graded material (FGM) sandwich double curved shallow shell,thermo-mechanical stability FGM stiffener elastic foundation

Mechanical and thermal postbuckling of FGM thick circular cylindrical shells reinforced by FGM stiffener system using higher-order shear deformation theory

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Applied Mathematics and Mechanics(English Edition) 2017年第1期38卷 73-98页

作者： D.v.dung H.T.THIEM Faculty of Mathematics Mechanics and InformaticsVietnam National UniversityHanoi 100000Vietnam

The postbuckling of the eccentrically stiffened circular cylindrical shells made of functionally graded materials （FGMs）, subjected to the axial compressive load and external uniform pressure and filled inside by the elastic foundations in the thermal environments, is investigated with an analytical method. The shells are reinforced by FGM stringers and rings. The thermal elements of the shells and stiffeners in the fundamental equations are considered. The equilibrium and nonlinear stability equations in terms of the displacement components for the stiffened shells are derived with the third-order shear deformation theory and Leckhniskii smeared stiffener technique. The closed-form expressions for determining the buckling load and postbuckling load-deflection curves are obtained with the Galerkin method. The effects of the stiffeners, the foundations, the material and dimensional parameters, and the pre-existent axial compressive and thermal load are considered.

关键词： stiffened cylindrical shell functionally graded material (FGM) postbuck- ling elastic foundation analytical

Nonlinear analysis on dynamic buckling of eccentrically stiffened functionally graded material toroidal shell segment surrounded by elastic foundations in thermal environment and under time-dependent torsional loads

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Applied Mathematics and Mechanics(English Edition) 2016年第7期37卷 835-860页

作者： D.v.dung P.M.vUONG Department of Mathematics Mechanics and InformaticsVietnam National University Faculty of Civil and Industrial National University of Civil Engineering

The nonlinear analysis with an analytical approach on dynamic torsional buckling of stiffened functionally graded thin toroidal shell segments is investigated. The shell is reinforced by inside stiffeners and surrounded by elastic foundations in a thermal environment and under a time-dependent torsional load. The governing equations are derived based on the donnell shell theory with the yon Karman geometrical nonlinearity, the Stein and McElman assumption, the smeared stiffeners technique, and the Galerkin method. A deflection function with three terms is chosen. The thermal parameters of the uniform temperature rise and nonlinear temperature conduction law are found in an explicit form. A closed-form expression for determining the static critical torsional load is obtained. A critical dynamic torsional load is found by the fourth-order Runge-Kutta method and the Budiansky-Roth criterion. The effects of stiffeners, foundations, material, and dimensional parameters on dynamic responses of shells are considered.

关键词： toroidal shell segment functionally graded material (FGM) stiffened shell,critical static and dynamic torsional load thermal environment

Nonlinear stability of functionally graded material(FGM)sandwich cylindrical shells reinforced by FGM stiffeners in thermal environment

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Applied Mathematics and Mechanics(English Edition) 2017年第5期38卷 647-670页

作者： D.v.dung N.T.NGA L.K.HOA Faculty of Mathematics Mechanics and InformaticsVietnam National UniversityHanoi 100000Vietnam Faculty of Basic Science Military Logistic AcademyHanoi 100000Vietnam

In this paper, donnell＇s shell theory and smeared stiffeners technique are improved to analyze the postbuckling and buckling behaviors of circular cylindrical shells of stiffened thin functionally graded material （FGM） sandwich under an axial loading on elastic foundations, and the shells are considered in a thermal environment. The shells are stiffened by FGM rings and stringers. A general sigmoid law and a general power law are proposed. Thermal elements of the shells and reinforcement stiffeners are considered. Explicit expressions to find critical loads and postbuckling load-deflection curves are obtained by applying the Galerkin method and choosing the three-term approximate solution of deflection. Numerical results show various effects of temperature, elastic foundation, stiffeners, material and geometrical properties, and the ratio between face sheet thickness and total thickness on the nonlinear behavior of shells.

关键词： functionally graded material (FGM) stiffened cylindrical shell sandwich,thermal environment

A Cyborg Insect Reveals a Function of a Muscle in Free Flight

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Cyborg and Bionic Systems 2022年第1期2022卷 98-108页

作者： T.Thang vo-doan v.Than dung Hirotaka Sato Nanyang Technological University School of Mechanical and Aerospace EngineeringSingapore University of Freiburg Institute of Biology I Germany

While engineers put lots of effort,resources,and time in building insect scale micro aerial vehicles(MAvs)that fly like insects,insects themselves are the real masters of *** if we would use living insect as platform for MAv instead?Here,we reported a flight control via electrical stimulation of a flight musde of an insect-computer hybrid robot,which is the interface of a mountable wireless backpack controller and a living *** beetle uses indirect flight muscles to drive wing flapping and three major direct flight muscles(basalar,subalar,and third axilliary(3Ax)muscles)to control the kinematics of the wings for flight *** turning control was already achieved by stimulating basalar and 3Ax muscles,electrical stimu lation of subalar musdes resulted in braking and elevation control in *** also demonstrated around 20 degrees of contralateral yaw and roll by stimulating individual subalar *** both subalar muscles lead to an increase of 20 degrees in pitch and decelerate the flight by 1.5 m/s2 as well as an induce in elevation of 2m/s.

关键词： robot computer mount

Buckling analysis of functionally graded material(FGM) sandwich truncated conical shells reinforced by FGM stiffeners filled inside by elastic foundations

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Applied Mathematics and Mechanics(English Edition) 2016年第7期37卷 879-902页

作者： D.v.dung L.K.HOA B.T.THUYET N.T.NGA Faculty of Mathematics Mechanics and Informatics Vietnam National University Faculty of Basic Science Military Logistic AcademyHanoi Faculty of Mining Hanoi University of Mining and Geology

An analytical solution for buckling of an eccentrically stiffened sandwich truncated conical shell is investigated. The shell consists of two functionally graded material （FGM） coating layers and a core layer which are metal or ceramic subjected to an axial compressive load and an external uniform pressure. Shells are reinforced by stringers and rings, in which the material properties of shells and stiffeners are graded in the thickness direction following a general sigmoid law distribution. Two models of coated shell-stiffener arrangements are investigated. The change of the spacing between stringers in the meridional direction is taken into account. A couple set of three-variable- coefficient partial differential equations in terms of displacement components are solved by the Galerkin method. A closed-form expression for determining the buckling load is obtained. The numerical examples are presented and compared with previous works.

关键词： functionally graded material (FGM) sandwich truncated conical shell,stiffener elastic foundation buckling analysis

Self-assembly of colloidal nanoparticles into encapsulated hollow superstructures

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Aggregate 2022年第1期3卷 188-196页

作者： Chaolumen Wu Zhiwei Li Yaocai Bai dung To Nosang v.Myung Yadong Yin Department of Chemistry University of CaliforniaRiversideCaliforniaUSA Department of Chemical and Biomolecular Engineering University of Notre DameNotre DameIndianaUSA

As a distinct type of nanocapsules,hollow superstructures of inorganic nanoparticles have attracted increasing attention due to their controllable permeability,convenient functionalization,and efficient surface ***,they are produced by assembling nanoparticles against expensive sacrificial ***,a general emulsion-based method is reported to assemble colloidal nanoparticles into submicron hollow superstructures,involving first co-assembly of colloidal nanoparticles with organic additives to form clusters,then overcoating the clusters with a polymer shell,and finally removing the organic additives and re-dispersing nanoparticles by exposing to a good *** key to the success of this process is the re-assembly of nanoparticles against the polymer shells as driven by the capillary force during solvent evaporation,producing hollow *** a space-confined assembly process can be well controlled by choice of solvents and their evaporation *** general technique provides an open and low-cost platform for creating hollow superstructures of various inorganic nanoparticles,offering many opportunities for exploring unique applications that can take advantage of the collective properties of the constituent nanoparticles and the permeable nanoshell structures.

关键词： emulsion hollow superstructures nanoparticles space-confined assembly

Hydrogen roles approaching ideal electrical and optical properties for undoped and Al doped ZnO thin films

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Journal of Materiomics 2022年第1期8卷 123-135页

作者： dung van Hoang Nam Hoang vu Nga Thi do Anh Tuan Thanh Pham Truong Huu Nguyen Jer-Lai Kuo Thang Bach Phan vinh Cao Tran Laboratory of Advanced Materials University of ScienceHoChiMinh City700000Viet Nam vietnam National University HoChiMinh City700000Viet Nam HoChiMinh City Institute of Physics HoChiMinh City700000Viet Nam Institute of Atomic and Molecular Sciences Academia SinicaTaipei10617Taiwan Center for Innovative Materials and Architectures(INOMAR) HoChiMinh City700000Viet Nam Faculty of Materials Science&Technology University of ScienceHoChiMinh City700000Viet Nam

This paper distinguished hydrogen roles to improve electron mobility and carrier concentration in ZnO and Al doped ZnO sputtered *** combining experimental evidences and theoretical results,we find out that hydrogen located at oxygen vacancy sites(H_(O))is the main factor gives rise to increase simultaneously mobility and carrier concentration which has not been mentioned *** appropriate hydrogen content during sputtering not only results in crystalline relaxation but also supports doping Al into ZnO,increasing carrier concentration and electron mobility in the *** principles calculations confirmed hydrogen substitutional stability for oxygen vacancy,significantly reducing electron conductivity effective mass and hence increasing electron *** particular,0.8%hydrogen partial pressure ratio achieved 61 cm^(2)v^(-1)s^(-1)maximum electron mobility,optical transmittance above 82%in visible and near-infrared regions,and 2×10^(20) cm^(-3)carrier concentrations for H-Al co-doped ZnO *** values approach ideal electrical and optical properties for transparent conducting oxide *** presence of one maximum electron mobility was attributed to competition between increasing mobility due to restoring effective electron mass and hydrogen passivation of native defects,and decreased electron mobility due to electron-phonon scattering.

关键词： High electron mobility Hydrogen roles Passivation effects Effective electron mass DFT calculations doped ZnO thin Film