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Atomic resolution in noncontact AFM by probing cantilever frequency shifts

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China Particuology 2007年第3期5卷 242-246页

作者： Hong yong xie Department of Environmental Engineering Shanghai Second Polytechnic University 2360 Jin Hai Road Pudong Shanghai 201209 China

Rutile TiO2 （001） quantum dots （or nano-marks） in different shapes were used to imitate uncleaved material surfaces or materials with rough surfaces. By numerical integration of the equation of motion of cantilever for silicon tip scanning along the [110] direction over the rutile TiO2 （001） quantum dots in ultra high vacuum （UHV）, scanning routes were explored to achieve atomic resolution from frequency shift image. The tip-surface interaction forces were calculated from Lennard-Jones （12-6） potential by the Hamaker summation method. The calculated results showed that atomic resolution could be achieved by frequency shift image for TiO2 （001） surfaces of rhombohedral quantum dot scanning in a vertical route, and spherical cap quantum dot scanning in a superposition route.2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.

关键词： Nc-AFM Frequency shift image Atomic resolution Quantum dots Uncleaved material surface

Behavior of Theta-series under Modular Substitutions

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Acta Mathematica Sinica,English Series 2011年第9期27卷 1705-1716页

作者： Bing yong xie LMAM School of Mathematical Science Peking University Beijing 10087'1 P. R. China

In this article we provide a transformation formula of certain theta series, and apply it to obtain non-holomorphic vector-valued modular forms.

关键词： Theta series nonholomorphic vector-valued modular forms

A new three-dimensional Hoek-Brown strength criterion

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Acta Mechanica Sinica 2012年第2期28卷 393-406页

作者： Hua Jiang yong-Li xie Key Laboratory for Bridgeand Tunnel of Shaanxi Province Chang'an University710064 Xi'anChina

The Hoek-Brown （HB） strength criterion has been widely applied to the estimation of strength of intact rock and rock mass, while evolving ever since. However, negligence of the effect of the intermediate principal stress still remains in the criterion＇s latest version. At the same time, several three-dimensional （3D） HB strength, which can takes into account the influence of the intermediate principal stress, have already been proposed, among which the 3D HB criterion proposed by Zhang and Zhu seems to be the most reasonable one. However, the Zhang 3D HB criterion may have problems with some stress path close to triaxial extension state because of the non-convexity characteristic of its failure surface. In this paper, a new 3D HB strength criterion is presented based on a generalized form of the HB criterion, which also considers the effect of the intermediate principal stress and inherits all the merits of the original version of the HB criterion. In addition, this new criterion can remedy to some extent the shortcomings observed in the Zhang 3D HB criterion. Polyaxial tests for five different rocks from pub- lished literatures are used for evaluating this new criterion and comparing it with the Zhang 3D HB criterion. The re- sults show that this new criterion may over-predict or under- predict the polyaxial strength of rocks but the errors are rela- tively small, and similar results are also found for the Zhang 3D HB criterion, which one is better depends on the type of the rock under estimation.

关键词： Hoek-Brown criterion Rock strength Merid-ian plane Octahedral plane

DYNAMIC MODELING AND ACTIVE CONTROL OF FLEXIBLE PLATE BASED ON THE INPUT-OUTPUT DATA

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Acta Mechanica Solida Sinica 2013年第3期26卷 255-262页

作者： yong xie Tong Zhao Guoping Cai Department of Engineering Mechanics State Key Laboratory of Ocean EngineeringShanghai Jiaotong University

This paper studies the low-order dynamic modeling and active control of a flexible plate and provides experimental verification. First based on the input-output data of the sys- tem, the Markov parameters of the system are identified using the method of observer/Kalman filter identification （OKID）. Then a low-order state-space model is built using the eigensystem realization algorithm （ERA）. Finally, a linear quadratic Gaussian （LQG） controller is designed based on the low-order state-space model. Experimental results have proved the effectiveness and feasibility of the research.

关键词： flexible plate OKID ERA active control experiment

Applications of advanced control methods in spacecrafts:progress, challenges, and future prospects

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Frontiers of Information Technology & Electronic Engineering 2016年第9期17卷 841-861页

作者： yong-chun xie Huang HUANG yong HU Guo-qi ZHANG Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control Engineering

We aim at examining the current status of advanced control methods in spacecrafts from an engineer's perspective. Instead of reviewing all the fancy theoretical results in advanced control for aerospace vehicles, the focus is on the advanced control methods that have been practically applied to spacecrafts during flight tests, or have been tested in real time on ground facilities and general testbeds/simulators built with actual flight data. The aim is to provide engineers with all the possible control laws that are readily available rather than those that are tested only in the laboratory at the moment. It turns out that despite the blooming developments of modern control theories, most of them have various limitations, which stop them from being practically applied to spacecrafts. There are a limited number of spacecrafts that are controlled by advanced control methods, among which H_2/H_∞ robust control is the most popular method to deal with flexible structures, adaptive control is commonly used to deal with model/parameter uncertainty, and the linear quadratic regulator(LQR) is the most frequently used method in case of optimal control. It is hoped that this review paper will enlighten aerospace engineers who hold an open mind about advanced control methods, as well as scholars who are enthusiastic about engineering-oriented problems.

关键词： Spacecraft control Robust control Adaptive control Optimal control

Influence of the Compacts Homogeneity on the Incidence of Cracks during Thermal Debinding in Ceramic Injection Molding

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Journal of Materials Science & Technology 2009年第2期25卷 264-268页

作者： Xianfeng Yang Zhipeng xie yong Huang State Key Laboratory of New Ceramics and Fine Processing Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

During thermal debinding in ceramic injection molding, the inhomogeneity of green body is a key origin of cracks. In this study, the impact of low molecular weight binders on the homogeneity of the green body was investigated. Incidence of cracks during thermal debinding indicated that the volume ratio of wax to stearic acid should be out of high viscosity and incompletely wetting region. In these two formulation regions, typical inhomogeneous microstructures were observed. By mercury intrusion method, it was shown that pore size distribution of the debinded compacts was determined by thermal degradation of low molecular weight binders. A particle-rich region model was established to predict the nucleation of cracks caused by solid loading fluctuation. The criterion of cracks nucleation was that local capillary force from solid loading fluctuation was larger than the suction force from the surroundings.

关键词： Ceramic injection molding Cracks Debinding Homogeneity

Rapid Growth of Ice Dendrite in Acoustically Levitated and Highly Undercooled Water

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Chinese Physics Letters 2002年第10期19卷 1543-1546页

作者： Lü yong-Jun, xie Wen-Jun Department of Applied Physics Northwestern Polytechnical University Xi\'an 710072

Water drops with diameters ranging from 2.5 to 4 mm are highly undercooled by up to 24 K with the acoustic levitation technique. Compared to the case of water contained in a tube, acoustic levitation has efficiently avoided the heterogeneous nucleation from container walls and consequently increased the undercooling level. However, the cavitation effect induced by ultrasound may prematurely catalyse nucleation, which hinders the further achievement of bulk undercooling. The growth velocity of ice dendrite determined experimentally in highly undercooled water is characteristic of rapid dendritic growth, which reaches 0.17 m/s at the undercooling of 24 K. The Lipton-Kurz-Trivedi dendritic growth model is used to predict the kinetic characteristics of rapid growth of ice dendrite under high undercooling conditions, which shows good agreement with the experimental results.

关键词： Ice

Firing properties and synchronization rate in fractional-order Hindmarsh-Rose model neurons

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Science China(Technological Sciences) 2014年第5期57卷 914-922页

作者： xie yong KANG YanMei LIU yong WU Ying State Key Lab of Strength and Vibration for Mechanical Structures Xi'an Jiaotong University School of Mathematics and Stastics Xi'an Jiaotong University

We find that the fractional-order Hindmarsh-Rose model neuron demonstrates various types of firing behavior as a function of the fractional order in this *** exists a clear difference in the bifurcation diagram between the fractional-order Hindmarsh-Rose model and the corresponding integer-order model even though the neuron undergoes a Hopf bifurcation to oscillation and then starts a period-doubling cascade to chaos with the decrease of the externally applied ***,the discharge frequency of the fractional-order Hindmarsh-Rose model neuron is greater than that of the integer-order counterpart irrespective of whether the neuron exhibits periodic or chaotic *** we demonstrate that the firing behavior of the fractional-order Hindmarsh-Rose model neuron has a higher complexity than that of the integer-order ***,the synchronization phenomenon is investigated in the network of two electrically coupled fractional-order model *** show that the synchronization rate increases as the fractional order decreases.

关键词： fractional calculus chaos bifurcation Hindmarsh-Rose model synchronization

Modal parameter identification of flexible spacecraft using the covariance-driven stochastic subspace identification(SSI-COV) method

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Acta Mechanica Sinica 2016年第4期32卷 710-719页

作者： yong xie Pan Liu Guo-Ping Cai Department of Engineering Mechanics State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University

In this paper, the on-orbit identification of modal parameters for a spacecraft is investigated. Firstly, the coupled dynamic equation of the system is established with the Lagrange method and the stochastic state-space model of the system is obtained. Then, the covariance-driven stochastic subspace identification（SSI-COV） algorithm is adopted to identify the modal parameters of the system. In this algorithm, it just needs the covariance of output data of the system under ambient excitation to construct a Toeplitz matrix, thus the system matrices are obtained by the singular value decomposition on the Toeplitz matrix and the modal parameters of the system can be found from the system matrices. Finally,numerical simulations are carried out to demonstrate the validity of the SSI-COV algorithm. Simulation results indicate that the SSI-COV algorithm is effective in identifying the modal parameters of the spacecraft only using the output data of the system under ambient excitation.

关键词： covariance stochastic subspace spacecraft modal validity matrices identifying excitation Toeplitz