Tairen Sun, J.M. Chen, J. D. Venables, R.L. Hopping,
Auger electron spectroscopy (AES) has been used to characterize the chemical composition of 2024-T3 Al alloy surfaces prepared by the Forest Products Laboratory (FPL) process. It is found that the chemical composition of an adherend surface depends not only on the method of surface preparation but also on the procedure by which an adhesive/Al bond is formed. A standard FPL etching with a 350°F bond curing operation causes excessive accumulations of Cu and Mg at the surface. The Cu accumulation is ...
Tópico(s): Electron and X-Ray Spectroscopy Techniques
1978 - Elsevier BV | Applications of Surface Science
Tairen Sun, S. Büchner, N. E. Byer, J. M. Chen,
The oxygen uptake of a molecular-beam-epitaxial Pb0.8Sn0.2Te(111) surface has been investigated by AES, XPS, and UPS studies. The results indicate a strong affiliation of oxygen with Sn ions. Oxidation of Sn starts at an exposure of 104 L, whereas oxidation of Pb and Te starts at an exposure of 106 L. Evidence indicates that Sn ions diffuse from the bulk to the surface in the process of oxygen chemisorption. A sharp increase of oxygen uptake is observed at an exposure of 106 L. It marks the commencement ...
Tópico(s): Semiconductor Quantum Structures and Devices
1978 - American Institute of Physics | Journal of Vacuum Science and Technology
J. M. Chen, Tairen Sun, R. K. Viswanadham, J. A. S. Green,
Tópico(s): Corrosion Behavior and Inhibition
1977 - Springer Science+Business Media | Metallurgical Transactions A
R. K. Viswanadham, Tairen Sun, J. A. S. Green,
Tópico(s): Non-Destructive Testing Techniques
1980 - Springer Science+Business Media | Metallurgical Transactions A
Tairen Sun, D.K. McNamara, J. S. Ahearn, J.M. Chen, B. M. Ditchek, J. D. Venables,
Tópico(s): Electron and X-Ray Spectroscopy Techniques
1980 - Elsevier BV | Applications of Surface Science
D. Ménétrier, I. Jawed, Tairen Sun, Jan Skalny,
Tópico(s): Minerals Flotation and Separation Techniques
1980 - Elsevier BV | Cement and Concrete Research
D. Ménétrier, I. Jawed, Tairen Sun, Jan Skalny,
Electron Spectroscopy for Chemical Analysis (ESCA) and high-resolution Scanning Electron Microscopy (SEM) have been used to explore the phenomena occuring on the C3S∗ surface in the very early stages of hydration. Definite changes in the surface morphology and Ca to Si ratio were observed already after a few seconds of hydration. La spectroscopie de photoélectrons (ESCA) et la microscopie électronique à balayage (MEB) ont été utiliseés pour étudier les phénoměnes qui se produisent ǎ la surface du silicate ...
Tópico(s): Iron oxide chemistry and applications
1979 - Elsevier BV | Cement and Concrete Research
J. D. Venables, D.K. McNamara, J.M. Chen, Tairen Sun, R.L. Hopping,
The high resolution capabilities of a scanning transmission electron microscope (STEM) operated in the SEM mode have been used to examine the morphology of oxides on Al surfaces prepared for adhesive bonding by three commercial processes used in the aircraft industry. High resolution (≈ 30 Å) stereo micrographs obtained in this manner provide striking visual evidence for fine oxide protrusions which apparently interlock with the adhesive to enhance bond strength.
Tópico(s): Concrete Corrosion and Durability
1979 - Elsevier BV | Applications of Surface Science
Tairen Sun, J. M. Chen, R. K. Viswanadham, J. A. S. Green,
The loss of Mg from Mg-containing Al alloys during heat treatments is a well-known metallurgical problem. Recent studies revealed that regardless of whether the loss of Mg is via formation of MgO in air or via evaporation of Mg in vacuum, the kinetics is primarily controlled by a surface reaction and is described by the relation dC/dt=−M (C−C∞) where C is the Mg concentration in the specimen, and M and C∞ are temperature-dependent constants. However, the specimens used in these studies contained ...
Tópico(s): Aluminum Alloy Microstructure Properties
1979 - American Institute of Physics | Journal of Vacuum Science and Technology
Glyn Davis, Tairen Sun, J. S. Ahearn, J. D. Venables,
Tópico(s): Concrete Corrosion and Durability
1982 - Springer Science+Business Media | Journal of Materials Science
Glyn Davis, Tairen Sun, S. Büchner, N. E. Byer,
The composition and chemical states of the oxide, interface, and bulk semiconductor regions of Hg0.8Cd0.2Te with anodic oxide films of 360, 1200, 1600, and 1600 Å chemically etched to 1200 Å were analyzed with x-ray photoelectron spectroscopy combined with ion sputterng. The near interface semiconductor exhibits 30%–40% less Hg than the bulk semiconductor. Detailed depth profiles were measured for this Hg depletion region. The maximum depletion is independent of the oxide thickness, but its spatial ...
Tópico(s): Machine Learning in Materials Science
1981 - American Institute of Physics | Journal of Vacuum Science and Technology
Tairen Sun, Hailong Pei, Yongping Pan, Caihong Zhang,
We address the problem of environmental contour line tracking for a class of autonomous vehicles. A reference velocity is designed for the autonomous vehicles to do contour line tracking. Based on Lashall invariance principle, an ideal controller is designed for the vehicle with ideal model and ideal information about the environmental concentration function to track the desired contour line. For the vehicle with possibly modeling uncertainty, we combine a neural controller containing a wavelet ...
Tópico(s): Control Systems and Identification
2011 - Elsevier BV | Neurocomputing
Tairen Sun, Hailong Pei, Yongping Pan, Hongbo Zhou, Caihong Zhang,
This paper addresses the robust trajectory tracking problem for a robot manipulator in the presence of uncertainties and disturbances. First, a neural network-based sliding mode adaptive control (NNSMAC), which is a combination of sliding mode technique, neural network (NN) approximation and adaptive technique, is designed to ensure trajectory tracking by the robot manipulator. It is shown using the Lyapunov theory that the tracking error asymptotically converge to zero. However, the assumption on ...
Tópico(s): Adaptive Dynamic Programming Control
2011 - Elsevier BV | Neurocomputing
Tairen Sun, Hailong Pei, Yongping Pan, Caihong Zhang,
SUMMARY The paper addresses the problem of environmental boundary tracking for the nonholonomic mobile robot with uncertain dynamics and external disturbances. To do environmental boundary tracking, a reference velocity is designed for the nonholonomic mobile robot. In this paper, a radial basis function neural network (NN) is used to approximate a nonlinear function containing the uncertain model terms and the elements of the Hessian matrix of the environmental concentration function. Then, the ...
Tópico(s): Adaptive Control of Nonlinear Systems
2011 - Wiley | International Journal of Robust and Nonlinear Control
Yongping Pan, Meng Joo Er, Daoping Huang, Tairen Sun,
Tópico(s): Fuzzy Logic and Control Systems
2012 - Springer Science+Business Media | International Journal of Fuzzy Systems
Yongping Pan, Meng Joo Er, Tairen Sun,
This paper presents a methodology of asymptotically synchronizing two uncertain generalized Lorenz systems via a single continuous composite adaptive fuzzy controller (AFC). To facilitate controller design, the synchronization problem is transformed into the stabilization problem by feedback linearization. To achieve asymptotic tracking performance, a key property of the optimal fuzzy approximation error is exploited by the Mean Value Theorem. The composite AFC, which utilizes both tracking and modeling ...
Tópico(s): Neural Networks Stability and Synchronization
2012 - American Institute of Physics | Chaos An Interdisciplinary Journal of Nonlinear Science
Yongping Pan, Yu Zhou, Tairen Sun, Meng Joo Er,
In the H∞ tracking-based adaptive fuzzy controllers (HAFCs) of perturbed uncertain nonlinear systems, additional H∞ control terms would greatly degrade fuzzy approximation abilities, which violates the original intention of using fuzzy logic systems. To solve this problem, a composite HAFC (CHAFC), which combines the HAFC with composite adaptation technique, is proposed in this paper. Outside of the approximation region, a robust stabilization controller is developed to achieve semi-global stability ...
Tópico(s): Adaptive Dynamic Programming Control
2012 - Elsevier BV | Neurocomputing
Tairen Sun, Fei Liu, Hailong Pei, Yang He,
This study considers the leader-following formation problem for the nonholonomic mobile robots, where the dynamics of the leader robot is unknown to the follower. First, the leader-following formation is transformed into a special trajectory tracking. Then neural network observer by the follower robot is designed to estimate the dynamics of the leader robot and based on multiple sliding surface technique control laws are designed for the follower robot to track the leader robot in the desired separation ...
Tópico(s): Modular Robots and Swarm Intelligence
2012 - Institution of Engineering and Technology | IET Control Theory and Applications
Tairen Wang, Fei Li, Shengjian Tang,
FOXL2 is a transcription factor that is essential for ovarian development. Somatic mutations of FOXL2 are associated with ovarian granulosa cell tumorigenesis. In the present study, the expression of FOXL2 was suppressed by microRNAs using the Ago2 knockdown method in COV434 cells. Online bioinformatics tools were utilized to predict that FOXL2 expression may be repressed by miR-30 family members, and dual luciferase assay and western blotting were performed to demonstrate that FOXL2 is a target ...
Tópico(s): FOXO transcription factor regulation
2014 - Spandidos Publishing | Oncology Letters
Boris Bonn, Efstratios Bourtsoukidis, Tairen Sun, Heinz Bingemer, L. Rondo, U. Javed, J. Li, R. Axinte, Xin Li, T. Brauers, Hannah Sonderfeld, R. Koppmann, Andrey Sogachev, S. Jacobi, D. V. Spracklen,
Abstract. It has been claimed for more than a century that atmospheric new particle formation is primarily influenced by the presence of sulfuric acid. However, the activation process of sulfuric acid related clusters into detectable particles is still an unresolved topic. In this study we focus on the PARADE campaign measurements conducted during August/September 2011 at Mt Kleiner Feldberg in central Germany. During this campaign a set of radicals, organic and inorganic compounds and oxidants ...
Tópico(s): Air Quality and Health Impacts
2014 - Copernicus Publications | Atmospheric chemistry and physics
Caihong Zhang, Tairen Sun, Yongping Pan,
This paper addresses the leader-following formation problem of nonholonomic mobile robots. In the formation, only the pose (i.e., the position and direction angle) of the leader robot can be obtained by the follower. First, the leader-following formation is transformed into special trajectory tracking. And then, a neural network (NN) finite-time observer of the follower robot is designed to estimate the dynamics of the leader robot. Finally, finite-time formation control laws are developed for the ...
Tópico(s): Control and Dynamics of Mobile Robots
2014 - Hindawi Publishing Corporation | Mathematical Problems in Engineering
Yongping Pan, Haoyong Yu, Tairen Sun,
It is well-known that standard adaptive fuzzy control (AFC) can only guarantee uniformly ultimately bounded stability due to inherent fuzzy approximation errors (FAEs). This paper proves that standard AFC with proportional-derivative (PD) control can guarantee global asymptotic stabilization even in the presence of FAEs for a class of uncertain affine nonlinear systems. Variable-gain PD control is designed to globally stabilize the plant. An optimal FAE is shown to be bounded by the norm of the plant ...
Tópico(s): Adaptive Dynamic Programming Control
2014 - Institute of Electrical and Electronics Engineers | IEEE Transactions on Cybernetics
Yuebang He, Hailong Pei, Tairen Sun,
Abstract This paper addresses the robust and accurate trajectory tracking problem for unmanned helicopters in the presence of model uncertainties and external disturbances. First, the helicopter's model is simplified to a six‐degrees‐of‐freedom rigid body augmented with a simplified rotor dynamic model, with the model uncertainties and the external disturbances being treated as lumped unknown disturbances. Second, a nonlinear disturbance observer is designed to estimate this lumped disturbance. ...
Tópico(s): Advanced Control Systems Optimization
2013 - Wiley | Asian Journal of Control
Yongping Pan, Tairen Sun, Haoyong Yu,
High-gain observers have been extensively applied to construct output-feedback adaptive neural control (ANC) for a class of feedback linearizable uncertain nonlinear systems under a nonlinear separation principle. Yet due to static-gain and linear properties, high-gain observers are usually subject to peaking responses and noise sensitivity. Existing adaptive neural network (NN) observers cannot effectively relax the limitations of high-gain observers. This paper presents an output-feedback indirect ...
Tópico(s): Adaptive Dynamic Programming Control
2015 - Institute of Electrical and Electronics Engineers | IEEE Transactions on Neural Networks and Learning Systems
Yongping Pan, Tairen Sun, Haoyong Yu,
Summary This paper presents an online recorded data‐based design of composite adaptive dynamic surface control for a class of uncertain parameter strict‐feedback nonlinear systems, where both tracking errors and prediction errors are applied to update parametric estimates. Differing from the traditional composite adaptation that utilizes identification models and linear filters to generate filtered modeling errors as prediction errors, the proposed composite adaptation integrates closed‐loop tracking ...
Tópico(s): Stability and Controllability of Differential Equations
2016 - Wiley | International Journal of Robust and Nonlinear Control
Yongping Pan, Meng Joo Er, Tairen Sun, Bin Xu, Haoyong Yu,
For indirect adaptive fuzzy H∞ tracking control (AFHC) of perturbed uncertain nonlinear systems, sliding-mode control (SMC) compensation usually has to be applied to ensure stability and H∞ robustness of the closed-loop system. We prove that indirect AFHC without SMC compensation is sufficient to guarantee stable H∞ tracking under given initial conditions and parameter constraints. The control structure only includes an indirect adaptive fuzzy control term and a proportional derivative (PD) control ...
Tópico(s): Iterative Learning Control Systems
2016 - Elsevier BV | Neurocomputing
Tairen Sun, Jun Zhang, Yongping Pan,
Abstract In this paper, a composite‐errors‐based active disturbance rejection control law is proposed for surface vessels with exogeneous disturbances. The low‐frequency disturbances from wind, wave and ocean currents are estimated by a novel composite‐errors‐based extended state observer (ESO). Since the composite errors are composed of trajectory tracking errors and estimation errors, the disturbance rejection control is feedforward‐feedback composite control. The advantages of feedforward control ...
Tópico(s): Underwater Vehicles and Communication Systems
2017 - Wiley | Asian Journal of Control
Tairen Sun, Yongping Pan, Chenguang Yang,
A composite adaptive locally weighted learning (LWL) control approach is proposed for a class of uncertain nonlinear systems with system constraints, including state constraints and asymmetric control saturation in this paper.The system constraints are tackled by considering the control input as an extended state variable and introducing barrier Lyapunov functions (BLFs) into the backstepping procedure.The system uncertainty is approximated by a composite adaptive LWL neural networks (NNs), where a ...
Tópico(s): Adaptive Dynamic Programming Control
2017 - Elsevier BV | Applied Soft Computing
Yongping Pan, Tairen Sun, Yiqi Liu, Haoyong Yu,
In existing neural network (NN) learning control methods, the trajectory of NN inputs must be recurrent to satisfy a stringent condition termed persistent excitation (PE) so that NN parameter convergence is obtainable. This paper focuses on command-filtered backstepping adaptive control for a class of strict-feedback nonlinear systems with functional uncertainties, where an NN composite learning technique is proposed to guarantee convergence of NN weights to their ideal values without the PE condition. ...
Tópico(s): Neural Networks Stability and Synchronization
2017 - Elsevier BV | Neural Networks
Jun Zhang, Tairen Sun, Zhilin Liu,
Abrupt maneuvering or strong disturbances from sea waves probably lead to large roll motion of underactuated surface vessels, which severely affects stability of surface vessels. A novel path-following control for vessels with roll constraints is proposed by combining Kalman filter, disturbance observer and robust constrained model predictive control method. Firstly, a switched linear uncertain model with coupled surge, sway, roll and yaw is constructed for underactuated surface vessels. Then, an ...
Tópico(s): Fault Detection and Control Systems
2017 - Elsevier BV | Ocean Engineering