Thermal vibration analysis of thick laminated plates by the moving least squares differential quadrature method

Lanhe Wu 국제구조공학회 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.22 No.3

Trajectory Tracking Controller Design for Caterpillar Vehicles Using a Model Reference Adaptive Controller

Van Lanh Nguyen,Dae Hwan Kim,Sang Kwun Jeong,Choong Hwan Lee,Hak Kyeong Kim,Sang Bong Kim 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10

This paper proposes a trajectory tracking controller for Caterpillar Vehicles (CVs) with uncertain parameters that combines a kinematic controller based on a backstepping method and a dynamic controller based on a model reference adaptive controller (MRAC). To do this task, the followings are done. Firstly, a system configuration of the CV is described. Secondly, kinematic modeling and dynamic modeling of the CV with some uncertain parameters are presented. Thirdly, a kinematic controller is designed based on kinematic modeling such that a local posture tracking error vector converges to zero. Fourthly, a dynamic controller based on MRAC is designed based on dynamic modeling such that CV’s output velocity vector converge to a virtual control input vector. Thus, a trajectory tracking controller using backstepping-based MRAC is utilized to estimate these uncertain parameters. By choosing a suitable Lyapunov function candidate, system stability is guaranteed, and a control law and update laws are obtained. Finally, the simulation and experimental results are presented to verify the effectiveness of the proposed MRAC controller.

Differential cubature method for buckling analysis of arbitrary quadrilateral thick plates

Wu, Lanhe,Feng, Wenjie Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.3

In this paper, a novel numerical solution technique, the differential cubature method is employed to study the buckling problems of thick plates with arbitrary quadrilateral planforms and non-uniform boundary constraints based on the first order shear deformation theory. By using this method, the governing differential equations at each discrete point are transformed into sets of linear homogeneous algebraic equations. Boundary conditions are implemented through discrete grid points by constraining displacements, bending moments and rotations of the plate. Detailed formulation and implementation of this method are presented. The buckling parameters are calculated through solving a standard eigenvalue problem by subspace iterative method. Convergence and comparison studies are carried out to verify the reliability and accuracy of the numerical solutions. The applicability, efficiency, and simplicity of the present method are demonstrated through solving several sample plate buckling problems with various mixed boundary constraints. It is shown that the differential cubature method yields comparable numerical solutions with 2.77-times less degrees of freedom than the differential quadrature element method and 2-times less degrees of freedom than the energy method. Due to the lack of published solutions for buckling of thick rectangular plates with mixed edge conditions, the present solutions may serve as benchmark values for further studies in the future.

An analytical solution for static analysis of a simply supported moderately thick sandwich piezoelectric plate

Wu, Lanhe,Jiang, Zhiqing,Feng, Wenjie Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.5

This paper presents a theoretic model of a smart structure, a transversely isotropic piezoelectric thick square plate constructed with three laminas, piezoelectric-elastic-piezoelectric layer, by adopting the first order shear deformation plate theory and piezoelectric theory. This model assumes that the transverse displacements through thickness are linear, and the in-plane displacements in the mid-plane of the plate are not taken to be account. By using Fourier's series expansion, an exact Navier typed analytical solution for deflection and electric potential of the simply supported smart plate is obtained. The electric boundary conditions are being grounded along four vertical edges. The external voltage and non-external voltage applied on the surfaces of piezoelectric layers are all considered. The convergence of the present approach is carefully studied. Comparison studies are also made for verifying the accuracy and the applicability of the present method. Then some new results of the electric potentials and displacements are provided. Numerical results show that the electrostatic voltage is approximately linear in the thickness direction, while parabolic in the plate in-plane directions, for both the deflection and the electric voltage. These results are very useful for distributed sensing and finite element verification.

The Relationship between Information Distribution and Intention to Choose a University

NGUYEN Lanh Van,NGUYEN Dat Ngoc,NGUYEN Duyen Thi Kim 한국유통과학회 2022 유통과학연구 Vol.20 No.7

Purpose: Research on the intention to choose a university has an important role for universities in enrollment. The information element is considered essential to help students have specific information before making their decisions. However, how to distribute this information appropriately is an issue that needs to be studied. Therefore, this study was conducted to evaluate the influence of information distribution on intention to choose a university. Research design, data, and methodology: The study showed a survey on 259 samples from first-year students at public universities in Vietnam. PLS-SEM model was performed to find out the relationship between information distribution and intention to choose a university. Result: The results show that information quality and information helpfulness positively impact on attitudes towards universities. Attitude towards university has a positive effect on the intention to choose a university. Conclusion: From the results of this study, the authors also make some recommendations to help universities have good communication policies to improve their ability to attract students to choose a university. Quality and helpful information will help universities to be able to attract students more effectively to enroll based on an effective communication strategy.

Positioning and Trajectory Tracking for Caterpillar Vehicles in Unknown Environment

Van Lanh Nguyen,Dae Hwan Kim,Van Sy Le,Sang Kwun Jeong,Choong Hwan Lee,김학경,Sang Bong Kim 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.12

This paper proposes positioning and trajectory tracking for Caterpillar Vehicles (CVs) in unknown environments. To do these tasks, the following are performed. Firstly, a system modeling of the Caterpillar Vehicle is presented. Secondly, solving the complicated tracking control problem in unknown environments is a challenging mission. Therefore, to guarantee the Caterpillar Vehicle system to be strong robustness against external disturbances in the unknown environments, a MIMO robust servo controller for tracking the desired trajectory is designed by using a Linear Shift Invariant Differential (LSID) operator. The CVs are able to accomplish various tasks in dangerous places where workers cannot enter. Thirdly, the positioning of the CV can be obtained using a Simultaneous Localization and Mapping (SLAM) method. This paper develops perfectly the SLAM algorithm for positioning of the CV based on laser sensor Lidar. The main advantage of this method is that it does not need to use more landmarks. Landmarks can be obtained from the unknown environment. Thus, the CV can work even in unknown environments and unsafe places. Finally, to verify the effectiveness of the proposed MIMO robust servo controller and the SLAM positioning algorithm, the experimental results are presented. The experimental results demonstrate the adequate tracking performance of the proposed MIMO robust servo controller in the unknown environment.

Thermal vibration analysis of thick laminated plates by the moving least squares differential quadrature method

Wu, Lanhe Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.22 No.3

The stresses and deflections in a laminated rectangular plate under thermal vibration are determined by using the moving least squares differential quadrature (MLSDQ) method based on the first order shear deformation theory. The weighting coefficients used in MLSDQ approximation are obtained through a fast computation of the MLS shape functions and their partial derivatives. By using this method, the governing differential equations are transformed into sets of linear homogeneous algebraic equations in terms of the displacement components at each discrete point. Boundary conditions are implemented through discrete grid points by constraining displacements, bending moments and rotations of the plate. Solving this set of algebraic equations yields the displacement components. Then substituting these displacements into the constitutive equation, we obtain the stresses. The approximate solutions for stress and deflection of laminated plate with cross layer under thermal load are obtained. Numerical results show that the MLSDQ method provides rapidly convergent and accurate solutions for calculating the stresses and deflections in a multi-layered plate of cross ply laminate subjected to thermal vibration of sinusoidal temperature including shear deformation with a few grid points.

국경 간 전자상거래 물류서비스가 소비자 만족도에 미치는 영향: 중국 소비자 및 특성을 활용하여

소란하(SHAO LANHE),오진호(Jin-Ho Oh),박근식(Keun Sik Park) 한국통상정보학회 2021 통상정보연구 Vol.23 No.1

This study analyzed the factors affecting the satisfaction of logistics service of cross-border e-commerce. And the quality of logistics service according to the characteristics of consumers was analyzed. All respondents showed significant influence on satisfaction with logistics service in professionalism, speed, safety, convenience, economics, and kindness. In case of men, it was found that it affected the convenience and kindness of speed, and women had the influence of professionalism, safety and economics. Consumers with monthly incomes of less than 1.5 million won have an impact on professionalism, speed, safety, convenience, and economics. Consumers with monthly income of more than 1.5 million won have only a kindness effect. Consumers who use e-commerce shopping less than 3 times a month showed that speed, safety, convenience, and kindness affected. Consumers who use e-commerce shopping more than three times a month showed that professionalism, speed and economics affected. 본 연구에서는 중국 소비자들을 대상으로 국경 간 전자상거래의 물류서비스 만족도에 영향을 미치는 주요 요인이 무엇인지 살펴보고 소비자 특성에 따른 차이에 대해서 분석하였다. 전 응답자들은 전문성, 신속성, 안전성, 편의성, 경제성, 친절성 모두 물류서비스 만족도에 긍정적인 영향을 끼친 것으로 나타났다. 남성의 경우 신속성 편의성 친절성, 여성은 전문성, 안전성, 경제성이 물류서비스 만족도에 긍정적인 영향을 끼치는 것으로 나타났다. 월 소득 150만 이하의 소비자들은 전문성, 신속성, 안전성, 편리성, 경제성, 월 소득 150만 원 이상의 소비자들은 친절성만이 만족도에 긍정적인 영향을 끼치는 것으로 나타났다. 월 이용 횟수 3회 이하인 소비자들은 신속성, 안전성, 편리성, 친절성, 3회 이상 소비자들은 전문성, 신속성, 경제성이 만족도에 긍정적인 영향을 끼치는 것으로 나타났다.

High Performance of SWIR HgCdTe Photovoltaic Detector Passivated by ZnS

( Ngoc Tu Lanh ),안세영 ( Se Young An ),서상희 ( Sang Hee Suh ),김진상 ( Jin Sang Kim ) 한국센서학회 2004 센서학회지 Vol.13 No.2

N/A Short wave infrared (SWIR) photovoltaic devices have been fabricated from metal organic vapour phase epitaxy (MOVPE) grown n- on p- HgCdTe films on GaAs substrates. The MOVPE grown films were processed into mesa type discrete devices with wet chemical etching employed for meas delineation and ZnS surface passivatlon. ZnS was thermally evaporated from effusion cell in an ultra high vacuum (UHV) chamber. The main features of the ZnS deposited from effusion cell in UHV chamber are low fixed surface charge density, and small hysteresis. It was found that a negative flat band voltage with-0.6 V has been obtained for Metal Insulator Semiconductor (MIS) capacitor which was evaporated at 910°C for 90 min. Current-Voltage (I-V) and temperature dependence of the I-V characteristics were measured in the temperature range 80 ~ 300 K. The Zero bias dynamic resistance-area product (R_(0)A) was about 7500Ω- cm² at room temperature. The physical mechanisms that dominate dark current properties in the HgCdTe photodiodes are examined by the dependence of the RA product upon reciprocal temperature. From theoretical considerations and known current expressions for thermal and tunnelling process, the device is shown to be diffusion limited up to 180 K and g-r limited at temperature below this.

A MIMO Robust Servo Controller Design for Three-Wheeled Automated Guided Vehicles Using a Linear Shift Invariant Differential Operator

Nguyen Van Lanh,Sung-Won Kim(김성원),Dae-Hwan Kim(김대환),Choong-Hwan Lee(이충환),Hak-Kyeong Kim(김학경),Sang-Bong Kim(김상봉) 제어로봇시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.12

This paper proposes a multi-input multi-output (MIMO) robust servo controller design for three-wheeled Omnidirectional Automated Guided Vehicles (OAGVs) with a disturbance to track desired references using a linear shift invariant differential (LSID) operator. To design the proposed MIMO robust servo controller, the followings are performed. Firstly, a MIMO model of a threewheeled OAGV is presented. Secondly, by operating the LSID operator according to a state-space model and an output error vector, a new extended system and a new control law are obtained. Thirdly, the proposed MIMO robust servo controller for the given threewheeled OAGV is designed by using the pole assignment approach. Fourthly, by applying the inverse LSID operator, a servo compensator and a control law for the MIMO system are obtained. Finally, to verify the effectiveness of the proposed MIMO robust servo controller, the numerical simulation and experimental results are presented. The simulation and experimental results demonstrate that the proposed MIMO robust servo controller has adequate tracking performance under an external disturbance and complicated higher-order reference signals such as step, ramp, and parabola. These results are compared with those of the sliding mode control method proposed by N. Hung in 2010. The proposed MIMO robust servo controller demonstrates faster tracking performance than the sliding mode control method.