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控制理论与应用（英文版） 2010年第3期8卷 326-332页

作者： tong heng lee Department of Electrical and Computer Engineering National University of Singapore (NUS)

A new dynamic model for cell-deformation-induced adenosine triphosphate （ATP） release from vascular endothelial cells （VECs） is proposed in this paper to quantify the relationship between the ATP concentration at the surface of VECs and blood flow-induced shear stress. The simulation results demonstrate that ATP concentration at the surface of VECs predicted by the proposed new dynamic model is more consistent with the experimental observations than those by the existing static and dynamic models. Furthermore, it is the first time that a proportional-integral-derivative （PID） feedback controller is applied to modulate extracellular ATP concentration. Three types of desired ATP concentration profiles including constant, square wave and sinusoid are obtained by regulating the wall shear stress under this PID control. The systematic methodology utilized in this paper to model and control ATP release from VECs via adjusting external stimulus opens up a new scenario where quantitative investigations into the underlying mechanisms for many biochemical phenomena can be carded out for the sake of controlling specific cellular events.

关键词： Dynamic modeling Control ATP Shear stress Vascular endothelial cells

HARD DISK DRIVES CONTROL IN MOBILE APPLICATIONS

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Journal of Systems Science & Complexity 2007年第2期20卷 215-224页

作者： Shuzhi Sam GE Beibei REN tong heng lee Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore Faculty of Engineering National University of Singapore Singapore 119260 Singapore

In this paper, control design is investigated for hard disk drives in mobile applications with unknown external arbitrarily fast time-varying disturbances. The disturbances can be estimated with exponential accuracy using the proposed disturbance observer based on a series of integral filters. The position error signal will converge to zero with the proposed control technique for systems subjected to the unknown disturbances. The effectiveness of the proposed method is demonstrated by extensive simulation studies.

关键词： Hard disk drives time-varying disturbances

Robust adaptive neuro-fuzzy control of uncertain nonholonomic systems

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控制理论与应用（英文版） 2010年第2期8卷 125-138页

作者： Shuzhi Sam GE Chee Khiang PANG tong heng lee Data Storage Institute A*STAR 5 Engineering Drive 1 (Off Kent Ridge Crescent NUS) Singapore 117608

In this paper, we present an adaptive neuro-fuzzy controller design for a class of uncertain nonholonomic systems in the perturbed chained form with unknown virtual control coefficients and strong drift nonlinearities. The robust adaptive neuro-fuzzy control laws are developed using state scaling and backstepping. Semiglobal uniform ultimate bound-edness of all the signals in the closed-loop are guaranteed, and the system states are proven to converge to a small neigh-borhood of zero. The control performance of the closed-loop system is guaranteed by appropriately choosing the design parameters. By using fuzzy logic approximation, the proposed control is free of control singularity problem. An adaptive control-based switching strategy is proposed to overcome the uncontrollability problem associated with x 0 (t 0 ) = 0.

关键词： Neuro-fuzzy control Nonholonomic systems Motion control

Role playing learning for socially concomitant mobile robot navigation

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CAAI Transactions on Intelligence Technology 2018年第1期3卷 49-58页

作者： Mingming Li Rui Jiang Shuzhi Sam Ge tong heng lee Department of Electrical and Computer Engineering and the Social Robotics Lab Smart System Institute (SSI) National University of Singapore Singapore 117576 Singapore

In this study, the authors present the role playing learning scheme for a mobile robot to navigate socially with its human companion in populated environments. Neural networks （NNs） are constructed to parameterise a stochastic policy that directly maps sensory data collected by the robot to its velocity outputs, while respecting a set of social norms. An efficient simulative learning environment is built with maps and pedestrians trajectories collected from a number of real-world crowd data sets. In each learning iteration, a robot equipped with the NN policy is created virtually in the learning environment to play itself as a companied pedestrian and navigate towards a goal in a socially concomitant manner. Thus, this process is called role playing learning, which is formulated under a reinforcement learning framework. The NN policy is optimised end-to-end using trust region policy optimisation, with consideration of the imperfectness of robot＇s sensor measurements. Simulative and experimental results are provided to demonstrate the efficacy and superiority of the proposed method.

关键词：学习环境人工智能发展现状智能技术

Compensation of hysteresis in piezoelectric actuator with iterative learning control

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控制理论与应用（英文版） 2010年第2期8卷 176-180页

作者： Kok Kiong TAN Andi Sudjana PUTRA tong heng lee Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Graduate School for Integrative Sciences and Engineering National University of Singapore Singapore 117576

This paper presents the application of iterative learning control (ILC) to compensate hysteresis in a piezoelectric actuator. The proposed controller is a hybrid of proportional-integral-differential (PID) control, whose main function is for trajectory tracking, and a chatter-based ILC, whose main function is for hysteresis compensation. Stability analysis of the proposed ILC is presented, with the PID included in the dynamic of the piezoelectric actuator. The performance of the proposed controller is analysed through simulation and verified with experiment with a piezoelectric actuator.

关键词： Iterative learning control Hysteresis Piezoelectric actuator Stability analysis

Frequency-domain L2-stability conditions for time-varying linear and nonlinear MIMO systems

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Control Theory and Technology 2014年第1期12卷 13-34页

作者： Zhihong HUANG Y. V. VENKATESH Cheng XIANG tong heng lee Department of Electrical & Computer Engineering National University of Singapore Singapore

The paper deals with the g2-stability analysis of multi-input-multi-output （MIMO） systems, governed by integral equations, with a matrix of periodic/aperiodic time-varying gains and a vector of monotone, non-monotone and quasi-monotone nonlin- earities. For nonlinear MIMO systems that are described by differential equations, most of the literature on stability is based on an application of quadratic forms as Lyapunov-function candidates. In contrast, a non-Lyapunov framework is employed here to derive new and more general g2-stability conditions in the frequency domain. These conditions have the following features： i） They are expressed in terms of the positive definiteness of the real part of matrices involving the transfer function of the linear time-invariant block and a matrix multiplier function that incorporates the minimax properties of the time-varying linear/nonlinear block, ii） For certain cases of the periodic time-varying gain, they contain, depending on the multiplier function chosen, no restrictions on the normalized rate of variation of the time-varying gain, but, for other periodic/aperiodic time-varying gains, they do. Overall, even when specialized to periodic-coefficient linear and nonlinear MIMO systems, the stability conditions are distinct from and less restrictive than recent results in the literature. No comparable results exist in the literature for aperiodic time-varying gains. Furthermore, some new stability results concerning the dwell-time problem and time-varying gain switching in linear and nonlinear MIMO systems with periodic/aperiodic matrix gains are also presented. Examples are given to illustrate a few of the stability theorems.

关键词： Circle criterion K-P-Y lemma L2-stability Lur'e problem Multiplier function Nyquist's criterion Switched systems Time-varying system

Boosting hydrocarbon conversion via Cu-doping induced oxygen vacancies on CeO2 in CO2 electroreduction

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Journal of Energy Chemistry 2025年第1期100卷 66-76页

作者： Lei Xue tong Shi Chenhui Han heng Zhang Fenrong Liu Haorun Li Yan Wang Xiaojun Gu Shanghong Zeng Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials School of Chemistry and Chemical Engineering Inner Mongolia University State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences Institute of Catalysis Department of Chemistry Zhejiang University National Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization Baotou Research Institute of Rare Earths

Conversion of CO2back to hydrocarbons is the most direct way of closing the“carbon cycle”,and its significance is further enlarged if this process is driven by renewable energies such as ***,precisely controlling the product selectivity towards hydrocarbons against the competitive hydrogen evolution remains challenging,especially for Cu-based ***,we report a novel defect engineering strategy,by which Cu-doping-induced oxygen vacancies on CeO2nanorods were effectively created,with adjustable vacancy/Cu *** resulting optimum catalyst shows up to 79% catalytic current density to hydrocarbons （excluding CO）,with 49% faradaic efficiency to *** and density functional theory unveil that the ratio between oxygen vacancy and Cu affects significantly the formation of*CHO and activation of H2O,which leads to the following deep hydrogenation to *** findings may spur new insights for designing and developing more controllable chemical process relevant to CO2utilization.

关键词： Oxygen vacancy Hydrocarbon production Reaction mechanism

Multi-scale strength analysis of bolted connections used in integral thermal protection system

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Chinese Journal of Aeronautics 2018年第8期31卷 1728-1740页

作者： heng LIANG Yuqing WANG Mingbo tong Junhua ZHANG College of Aerospace Engineering Ministerial Key Discipline Laboratory of Advanced Design Technology of Aircraft Nanjing University of Aeronautics & Astronautics Nanjing 210016 China Shanghai Aircraft Design and Research Institute Shanghai 201210 China

Efficient and accurate strength analysis of bolted connections is essential in analyzing the integral thermal protection system（ITPS） of hypersonic vehicles, since the system bears severe loads and structural failures usually occur at the connections. Investigations of composite mechanical properties used in ITPS are still in progress as the architecture of the composites is complex. A new method is proposed in this paper for strength analysis of bolted connections by investigating the elastic behavior and failure strength of three-dimensional C/C orthogonal composites used in ITPS. In this method a multi-scale finite element method incorporating the global–local method is established to ensure high efficiency in macro-scale and precision in meso-scale in *** results reveal that predictions of material properties show reasonable accuracy compared with test results. And the multi-scale method can analyze the strength of connections efficiently and accurately.

关键词： Bolted connection Composite Multi-scale method Strength analysis Thermal Protection System

Efficient Estimation for Semiparametric Varying-Coefficient Partially Linear Regression Models with Current Status Data

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Acta Mathematicae Applicatae Sinica 2009年第2期25卷 195-204页

作者： Tao Hu heng-jian Cui Xing-wei tong School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems Ministry of Education Beijing 100875 China

This article considers a semiparametric varying-coefficient partially linear regression model with current status data. The semiparametric varying-coefficient partially linear regression model which is a generalization of the partially linear regression model and varying-coefficient regression model that allows one to explore the possibly nonlinear effect of a certain covariate on the response variable. A Sieve maximum likelihood estimation method is proposed and the asymptotic properties of the proposed estimators are discussed. Under some mild conditions, the estimators are shown to be strongly consistent. The convergence rate of the estimator for the unknown smooth function is obtained and the estimator for the unknown parameter is shown to be asymptotically efficient and normally distributed. Simulation studies are conducted to examine the small-sample properties of the proposed estimates and a real dataset is used to illustrate our approach.

关键词： Partly linear model varying-coefficient current status data asymptotically efficient estimator sieve MLE

Development characteristics and quantitative prediction of reservoir fractures in the Chaoyanggou oil field

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Mining Science and Technology 2009年第3期19卷 373-379页

作者： ZHANG Zhen tong heng-mao BAO Zhi-dong Faculty of Natural Resource ＆ Information Technology China University of Petroleum Beijing 102249 China State Key Laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China

The Chaoyanggou oil field is a fractured low-permeability reservoir, where the distribution of oil and gas is controlled by the distribution and development of *** on outcrop, drilling core, thin section and log data, the development characteristics of fractures in this area are *** this basis, the degree of fracture development was predicted by quantitative analysis of fracture strength and numerical *** result shows that four groups of structural fractures, i.e., in near NS, and EW directions and in due NW and NE directions, were developed in the reservoir, with the nearly NS and EW fractures dominant, which are the along bedding decollement fractures formed by compressive folding action, while low angle shear fractures are related to *** fractures are mainly formed in the reversed tectonic stage at the end of the Mingshui formation during the Cretaceous *** degree of fracture development is controlled by such factors as lithology, stratum thickness, faults, folds and *** fractures are developed with a clear zonation and are best developed in the northern zone, moderately developed towards the south and poorly developed in the middle *** prediction results are in good agreement with interpretation results from logs.

关键词： fracture development characteristic fracture strength numerical simulation Chaoyanggou oil field