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Flow Visualization of Rhinoceros Beetle （Trypoxylus dichotomus） in Free Flight

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Journal of Bionic Engineering 2012年第3期9卷 304-314页

作者： Tien Van Truong tuyen quang le Hieu Trung Tran Hoon Cheol Parka Kwang Joon Yoon Doyoung Byun . Department of Aerospace Information Engineering Konkuk University Seoul 143-70 l Republic of Korea 2.Costal Engineering and Ocean Energy Research Department Korea Ocean Research and Development Institute 454 Haeanro Sangrok-gu Ansan 426-744 Republic of Korea Department of Advanced Technology Fusion Konkuk University Seoul 143-701 Republic of Korea Department of Mechanical Engineering Sungkyunkwan University Suwon 440-746 Republic of Korea

Aerodynamic characteristics of the beetle, Trypoxylus dichotomus, which has a pair of elytra （forewings） and flexible hind wings, are investigated. Visualization experiments were conducted for various flight conditions of a beetle, Trypoxylus di- chotomus： free, tethered, hovering, forward and climbing flights. leading edge, trailing edge and tip vortices on both wings were observed clearly. The leading edge vortex was stable and remained on the top surface of the elytron for a wide interval during the downstroke of free forward flight. Hence, the elytron may have a considerable role in lift force generation of the beetle. In addition, we reveal a suction phenomenon between the gaps of the hind wing and the elytron in upstroke that may improve the positive lift force on the hind wing. We also found the reverse clap-fling mechanism of the T. dichotomus beetle in hovering flight. The hind wings touch together at the beginning of the upstroke. The vortex generation, shedding and interaction give a better understanding of the detailed aerodynamic mechanism of beetle flight.

关键词： beetle smoke wire visualization free flight hovering flight wing interaction elytron effect

Non-Jumping Take off Performance in Beetle Flight （Rhinoceros Beetle Trypoxylus dichotomus）

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Journal of Bionic Engineering 2014年第1期11卷 61-71页

作者： Tien Van Truong tuyen quang le Hoon Cheol Park Kwang Joon Yoon Min Jun Kim Doyoung Byun Department of Aerospace and Information Engineering Konkuk University Seoul South Korea Department of Mechanical Engineering National University of Singapore Singapore KoreaInstitute of Ocean Science and Technology PO Box 29 Ansan 425-600 South Korea Department of Advanced Technology Fusion Konkuk University Seoul South Korea Department of Mechanical Engineering and Mechanics Drexel University Philadelphia PA 19104 USA Department of Mechanical Engineering Sungkyunkwan University Suwon South Korea

In recent decades, the take-off mechanisms of flying animals have received much attention in insect flight initiation. Most of previous works have focused on the jumping mechanism, which is the most common take-off mechanism found in flying animals. Here, we presented that the rhinoceros beetle, Trypoxylus dichotomus, takes offwithout jumping. In this study, we used 3-Dimensional （3D） high-speed video techniques to quantitatively analyze the wings and body kinematics during the initiation periods of flight. The details of the flapping angle, angle of attack of the wings and the roll, pitch and yaw angles of the body were investigated to understand the mechanism of take-off in T. dichotomus. The beetle took off gradually with a small velocity and small acceleration. The body kinematic analyses showed that the beetle exhibited stable take-off. To generate high lift force, the beetle modulated its hind wing to control the angle of attack; the angle of attack was large during the upstroke and small during the downstroke. The legs of beetle did not contract and strongly release like other insects. The hind wing could be con- sidered as a main source of lift for heavy beetle.

关键词： take-oft non-jumping mechanism rhinoceros beetle kinematics

How Could Beetle＇s Elytra Support Their Own Weight during Forward Flight？

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Journal of Bionic Engineering 2014年第4期11卷 529-540页

作者： tuyen quang le Tien Van Truong Hieu TrungTran Soo Hyung Park Jin Hwan Ko Hoon Cheol Park Doyoung Byun Korea Institute of Ocean Science and Technology Ansan P. O. Box 29 425-600 South Korea Institute of High Performance Computing 1 Fusionopolis Way Singapore 138632 Singapore Department of Aerospace and Information Engineering Konkuk University Seoul South Korea Department of Mechanical Engineering National University of Singapore Singapore Department of Advanced Technology Fusion Konkuk University Seoul South Korea Department of Mechanical Engineering Sungkyunkwan University Suwon South Korea

The aerodynamic role of the elytra during a beetle＇s flapping motion is not well-elucidated, although it is well-recognized that the evolution of elytra has been a key in the success of coleopteran insects due to their protective function. An experimental study on wing kinematics reveals that for almost concurrent flapping with the hind wings, the flapping angle of the elytra is 5 times smaller than that of the hind wings. Then, we explore the aerodynamic forces on elytra in free forward flight with and without an effect of elytron-hind wing interaction by three-dimensional numerical simulation. The numerical results show that vertical force generated by the elytra without interaction is not sufficient to support even its own weight. However, the elytron-hind wing interaction improves the vertical force on the elytra up to 80%; thus, the total vertical force could fully support its own weight. The interaction slightly increases the vertical force on the hind wind by 6% as well.

关键词： wing interaction elytra beetle free forward flight three-dimensional numerical simulation

Two- and Three-Dimensional Simulations of Beetle Hind Wing Flapping during Free Forward Flight

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Journal of Bionic Engineering 2013年第3期10卷 316-328页

作者： tuyen quang le Tien Van Truong Hieu Trung Tran Soo Hyung Park Jin Hwan Ko Hoon Cheol Park Kwang Joon Yoon Doyoung Byun Korea Institute of Ocean Science and Technology PO Box 29 Ansan 425-600 Republic of Korea Department of Aerospace and Information Engineering Konkuk University Seoul Republic of Korea Department of Advanced Technology Fusion Konkuk University Seoul Republic of Korea Department of Mechanical Engineering Sungkyunkwan University Suwon440-746 Republic of Korea

Aerodynamic characteristic of the beetle, Trypoxylus dichotornus, which has a pair of elytra （forewings） and hind wings, is numerically investigated. Based on the experimental results of wing kinematics, two-dimensional （2D） and three-dimensional （3D） computational fluid dynamic simulations were carried out to reveal aerodynamic performance of the hind wing. The roles of the spiral leading Edge Vortex （leV） and the spanwise flow were clarified by comparing 2D and 3D simulations. Mainly due to pitching down of chord line during downstroke in highly inclined stroke plane, relatively high averaged thrust was produced in the free forward flight of the beetle. The effects of the local corrugation and the camber variation were also investigated for the beetle＇s hind wings. Our results show that the camber variation plays a significant role in improving both lift and thrust in the flapping. On the other hand, the local corrugation pattern has no significant effect on the aerodynamic force due to large angle of attack during flapping.

关键词： beetle flight forward flight three-dimensional simulation corrugation effect time-camber variation

Non-Zenoness of piecewise affine dynamical systems and affine complementarity systems with inputs

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Control Theory and Technology 2014年第1期12卷 35-47页

作者： le quang THUAN Department of Mathematics Quy Nhon University 170 An Duong Vuongy Quy Nhon Binh Dinh Vietnam

In the context of continuous piecewise affine dynamical systems and affine complementarity systems with inputs, we study the existence of Zeno behavior, i.e., infinite number of mode transitions in a finite-length time interval, in this paper. The main result reveals that continuous piecewise affine dynamical systems with piecewise real-analytic inputs do not exhibit Zeno behavior. Applied the achieved result to affine complementarity systems with inputs, we also obtained a similar conclusion. A direct benefit of the main result is that one can apply smooth ordinary differential equations theory in a local manner for the analysis of continuous piecewise affine dynamical systems with inputs.

关键词： Piecewise affine systems Zeno behavior Hybrid systems Affine complementarity systems

Finite element analysis of functionally graded sandwich plates with porosity via a new hyperbolic shear deformation theory

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Defence Technology（防务技术） 2022年第3期18卷 490-508页

作者： Pham Van Vinh le quang Huy Department of Solid Mechanics Le Quy Don Technical University236 Hoang Quoc VietHanoiViet Nam Institute of Techniques for Special Engineering Le Quy Don Technical University236 Hoang Quoc VietHanoiViet Nam

This study focusses on establishing the finite element model based on a new hyperbolic sheareformation theory to investigate the static bending,free vibration,and buckling of the functionally graded sandwich plates with *** novel sandwich plate consists of one homogenous ceramic core and two different functionally graded face sheets which can be widely applied in many fields of engineering and defence *** discrete governing equations of motion are carried out via Hamilton’s principle and finite element *** computation program is coded in MATLAB software and used to study the mechanical behavior of the functionally graded sandwich plate with *** present finite element algorithm can be employed to study the plates with arbitrary shape and boundary *** obtained results are compared with available results in the literature to confirm the reliability of the present ***,a comprehensive investigation of the effects of several parameters on the bending,free vibration,and buckling response of functionally graded sandwich plates is *** numerical results shows that the distribution of porosity plays significant role on the mechanical behavior of the functionally graded sandwich plates。

关键词： Functionally graded sandwich plates Porous plates Hyperbolic shear deformation theory Bending analysis Free vibration analysis Buckling analysis

A Deep learning Based Approach for Context-Aware Multi-Criteria Recommender Systems

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Computer Systems Science & Engineering 2023年第1期44卷 471-483页

作者： Son-Lam VU quang-Hung le Faculty of Information Technology Quy Nhon UniversityQuy Nhon CityVietnam

Recommender systems are similar to an informationfiltering system that helps identify items that best satisfy the users’demands based on their pre-ference ***-aware recommender systems(CARSs)and multi-criteria recommender systems(MCRSs)are extensions of traditional recommender *** have integrated additional contextual information such as time,place,and so on for providing better ***,the majority of CARSs use ratings as a unique criterion for building ***,MCRSs utilize user preferences in multiple criteria to better generate *** to now,how to exploit context in MCRSs is still an open *** paper proposes a novel approach,which relies on deep learning for context-aware multi-criteria recommender *** apply deep neural network(DNN)mod-els to predict the context-aware multi-criteria ratings and learn the aggregation *** conduct experiments to evaluate the effect of this approach on the real-world dataset.A significant result is that our method outperforms other state-of-the-art methods for recommendation effectiveness.

关键词： Recommender systems context-aware multi-criteria deep learning deep neural network

Iterative Method for Solving a Problem with Mixed Boundary Conditions for Biharmonic Equation

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Advances in Applied Mathematics and Mechanics 2009年第5期1卷 683-698页

作者： Dang quang A le Tung Son Institute of Information Technology 18 Hoang Quoc Viet Cau giayHanoiVietnam Pedagogic College Thai Nguyen UniversityVietnam

The solution of boundary value problems(BVP)for fourth order differential equations by their reduction to BVP for second order equations,with the aim to use the available efficient algorithms for the latter ones,attracts attention from many *** this paper,using the technique developed by the authors in recent works we construct iterative method for a problem with complicated mixed boundary conditions for biharmonic equation which is originated from nanofluidic *** convergence rate of the method is proved and some numerical experiments are performed for testing its dependence on a parameter appearing in boundary conditions and on the position of the point where a transmission of boundary conditions occurs.

关键词： Iterative method biharmonic equation mixed boundary conditions

The topology of foliations formed by the generic K-orbits of a subclass of the indecomposable MD_5-groups

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Science China Mathematics 2009年第2期52卷 351-360页

作者： VU le Anh HOA Duong quang Department of Mathematics and Informations University of Pedagogy Ho Chi Minh CityDistrict 5 Vietnam

The paper is a continuation of the authors' works in 2007. We consider the MD_5-foliations associated to connected and simply connected MD_5-groups such that their Lie algebras have 4-dimensional commutative derived ideals. In this study, we give a topological classification of all considered MD_5-foliations. A description of these foliations by certain fibrations or suitable actions of R2 and the Connes' C*-algebras of the foliations which come from fibrations are also given.

关键词： Lie group Lie algebra MD_5-group MD_5-algebra K-orbits foliation measured foliation