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Approximate Nonlinear Modeling of Aircraft Engine Surge Margin Based on Equilibrium Manifold Expansion

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Chinese Journal of Aeronautics 2012年第5期25卷 663-674页

作者： liu xiaofeng ZHAO Lei School of Transportation Science and Engineering Beihang UniversityBeijing 100191China

Stable operation of aircraft engine compressions is constrained by rotating surge. In this paper, an approximate nonlinear surge margin model of aircraft engine compression system by using equilibrium manifold is presented. Firstly, this paper gives an overview of the current state of modeling aerodynamic flow instabilities in engine compressors. Secondly, the expansion form of equilibrium manifold is introduced, and the choosing scheduling variable method is discussed. Then, this paper also gives the identification procedure of modeling the approximate nonlinear model. Finally, the modeling and simulations with high pressure （liP） compressor surge margin of the aircraft engine show that this real-time model has the same accuracy with the thermody- namic model, but has simpler structure and shorter computation time.

关键词： aircraft engine surge margin system identification equilibrium manifold scheduling variable perpendicular expan-sion

A Bayesian Game Approach for Demand Response Management Considering Incomplete Information

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Journal of Modern Power Systems and Clean Energy 2022年第2期10卷 492-501页

作者： xiaofeng liu Difei Tang Zhicheng Dai the School of Electrical and Automation Engineering Nanjing Normal UniversityNanjingChina State Grid Xuzhou Power Supply Company XuzhouChina

Residential flexible resource is attracting much attention in demand response(DR)for peak load *** paper proposes a scenario for multi-stage DR project to schedule energy consumption of residential communities considering the incomplete *** in the scenario can decide whether to participate in DR in each stage,but the decision is the private information that is unknown to other *** optimize the energy consumption,a Bayesian game approach is formulated,in which the probability characteristic of the decision-making of residential communities is described with Markov chain considering human behavior of bounded *** results show that the proposed approach can benefit all residential communities and power grid,but the optimization effect is slightly inferior to that in complete information game approach.

关键词： Demand response(DR) Bayesian game energy consumption scheduling Markov chain.

ALGORITHM FOR ACOUSTIC PASSIVE LOCALIZATION WITH DUAL ARRAYS

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 14-17页

作者： JIA Jingjing liu Mingjie LI xiaofeng School of Aerospace Science and Engineering Beijing Institute of Technology Beijing 100081 China

Aiming at the problem of 3D target localization by time delay estimation, this paper proposes a new acoustic passive localization method, which can provide high precision localization estimation. The first step of the two-stage algorithm is to measure the azimuth angle and pitch angle at each single array, which can obtain high precision angle estimation but low precision range estimation. And in the second step, the location of acoustic source is calculated from the angles measured above and geometry position of the two arrays. Then the accuracy of localization estimation is discussed in theory, and the influence factors and localization error are analyzed by simulation. The simulation results validate the performance of the proposed algorithm, and show the precision of localization estimation with dual arrays is superior to single array.

关键词： Acoustic passive localization Dual arrays Target tracking

On regularizing-rate estimates for solutions to the heat flow with initial value problem

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Science China Mathematics 2013年第3期56卷 653-664页

作者： WANG Meng liu xiaofeng Department of Mathematics Zhejiang University Department of Applied Mathematics School of Sciences Donghua University

For a compact Riemannian manifold NRK without boundary, we establish the existence of strong solutions to the heat flow for harmonic maps from Rn to N, and the regularizing rate estimate of the strong solutions. Moreover, we obtain the analyticity in spatial variables of the solutions. The uniqueness of the mild solutions in C([0,T]; W1,n) is also considered in this paper.

关键词： heat flow regularity gradient mild solution analyticity

Dynamics and control of variable geometry truss manipulator

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Applied Mathematics and Mechanics(English Edition) 2017年第2期38卷 243-262页

作者： xiaofeng liu Qishuai WANG Haiquan LI Guoping CAI Department of Engineering Mechanics State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai 200240 China

Variable geometry truss manipulator （VGTM） has potential to work in the future space applications, of which a dynamic model is important to dynamic analysis and control of the system. In this paper, an approach is presented to model the dynamic equations of a VGTM by independent variables, which consists of two double-octahedral truss units and a 3-revolute-prismatic-spherical （3-RPS） parallel manipulator. In this ap- proach, the kinematic recursive relations of two adjacent bodies and geometric constrains are used to deduce the kinematic equations of the VGTM, and Jourdain＇s velocity varia- tion principle is adopted to establish the dynamic equations of the system. The validity of the proposed dynamic model is verified by comparison of numerical simulations with the software ADAMS. Besides, an active controller for trajectory tracking of the system is designed by the computed torque method. The effectiveness of the controller is numer- ically proved.

关键词： variable geometry truss manipulator (VGTM) double-octahedral truss unit,3-revolute-prismatic-spherical (3-RPS) parallel manipulator dynamic modeling activecontrol

Tectonic-Hydrocarbon Accumulation of Laoyemiao Region in the Nanpu Sag,Bohai Bay Basin

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Acta Geologica Sinica(English Edition) 2009年第5期83卷 951-961页

作者： ZHANG Cuimei liu xiaofeng REN Jianye Key Laboratory of Tectonics and Petroleum Resources China University of Geosciences Wuhan 430074 China

This paper aims to gain insight into Laoyemiao （LYM） tectonic features and utilizes the tectonic-hydrocarbon accumulation model by integrated analysis tectonic controls on suitable reservoirs, trap styles, and hydrocarbon migration. On the basis of 3-D seismic data interpretation and the Xi＇nanzhuang （XNZ） Fault geometry analysis, it has been assessed that the LYM tectonics is essentially a transverse anticline produced by flexure of the XNZ Fault surface and superimposed by Neocene north-east-trending strike-slip faults. Transverse anticline is found to exert controls both on major sediment transportation pathways and sedimentary facies distribution. Fan-delta plains that accumulated on the anticline crest near the XNZ Fault scrap and fan-delta front on the anticline front and the upper part of both limbs slumps on synclines and the Linque subsag. In combination with the reservoir properties, suitable reservoirs are predicted in the subfacies of subaqueous distributary channel and mouth bar deposited on the anticline crest. The LYM-faulted anticline accounts for the following trap groups： faulted-block and anticline-dominated trap, fault-dominated traps, and combined and stratigraphic traps. Evidence from biomarkers of crude oil and hydrocarbon-filling period simultaneous, or a little later to the strike-slip fault activity, reveal that the *** faults penetrating into the deep source rock, by connecting with shallow reservoirs, provide the major hydrocarbon migration pathways.

关键词： tectonic-hydrocarbon accumulation Laoyemiao region Nanpu sag

Design for aircraft engine multi-objective controllers with switching characteristics

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Chinese Journal of Aeronautics 2014年第5期27卷 1097-1110页

作者： liu xiaofeng Shi Jing Qi Yiwen Yuan Ye School of Transportation Science and Engineering Beihang University School of Automation Shenyang Aerospace University School of Energy and Power Engineering Beihang University

The aircraft engine multi-loop control system is described and the switching control theory is introduced to solve the regulating and protecting control problems in this paper. The aircraft engine multi-loop control system is firstly described and the control problems are formulated. Secondly, the theory of the smooth switching control is devoted and a new extended scheme for the smooth switching of a switched control system is introduced. Then, for the key technologies of aero-engines switching control, a design algorithm is presented which can determine which candidate controller should be put in feedback with the plant to achieve a desired performance and the procedure to design the aircraft engine multi-loop control system is detailed. The switching performance objectives and the switching scheme are given and a family of PID controllers and compensators is designed. The simulation shows that using the switching control design method can not only improve the dynamic performance of the aircraft engine control system and reduce the switching times, but also guarantee the stability in some peculiar occasions.

关键词： Aircraft engine Compensatory controller Min/Max switching Multi-objectives control Smooth switching Switching scheme

IMPROVED METHOD FOR HILBERT INSTANTANEOUS FREQUENCY ESTIMATION

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Chinese Journal of Mechanical Engineering 2007年第6期20卷 94-98页

作者： BO Lin liu xiaofeng QIN Shuren College of Mechanical Engineering Chongqing University Chongqing 400044 China

In the mechanical fault detection and diagnosis field, it is more and more important to analyze the instantaneous frequency （IF） character of complex vibration signal. The improved IF estimation method is put forward aiming at the shortage of traditional Hilbert transform. It is based on Hilbert transform in wavelet domain. With the help of relationship between the real part and the imaginary part obtained from the complex coefficient of continuous wavelet transform or the analyti- cal signal reconstructed in wavelet packet decomposition, the instantaneous phase function of the subcomponent is extracted. In order to improve the precise of IF estimated out, some means such as Linear regression, adaptive filtering, resampling are applied into the instantaneous phase obtained, then, the central differencing operator is used to get desired IF. Simulation results with synthetic and gearbox fault signals are included to illustrate the proposed method.

关键词： Instantaneous frequency Hilbert transform Wavelet transform Linear regression Adaptive filtering Resampling

HYBRID WAVELET PACKET-TEAGER ENERGY OPERATOR ANALYSIS AND ITS APPLICATION FOR GEARBOX FAULT DIAGNOSIS

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Chinese Journal of Mechanical Engineering 2007年第6期20卷 79-83页

作者： liu xiaofeng QIN Shuren BO Lin College of Mechanical Engineering Chongqing University Chongqing 400044 China

Based on wavelet packet decomposition （WPD） algorithm and Teager energy operator （TEO）, a novel gearbox fault detection and diagnosis method is proposed. Its process is expatiated after the principles of WPD and TEO modulation are introduced respectively. The preprocessed sigaaal is interpolated with the cubic spline function, then expanded over the selected basis wavelets. Grouping its wavelet packet components of the signal based on the minimum entropy criterion, the interpolated signal can be decomposed into its dominant components with nearly distinct fault frequency contents. To extract the demodulation information of each dominant component, TEO is used. The performance of the proposed method is assessed by means of several tests on vibration signals collected from the gearbox mounted on a heavy truck. It is proved that hybrid WPD-TEO method is effective and robust for detecting and diagnosing localized gearbox faults.

关键词： Wavelet packet Teager energy operator Fault diagnosis Demodulation analysis