检索结果-南通市图书馆

Design of longitudinal predictive re-entry guidance law based on variable universe fuzzy-PI composite control

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

控制理论与应用（英文版） 2012年第2期10卷 264-267页

作者： Yin WANG 1 , Yuping LU 2 1.college of automation engineering, nanjing university of aeronautics and astronautics, nanjing Jiangsu{5., China 2.college of astronautics, nanjing university of aeronautics and astronautics, nanjing Jiangsu{5., China college of automation engineering Nanjing University of Aeronautics and Astronautics Nanjing Jiangsu China college of astronautics Nanjing University of Aeronautics and Astronautics Nanjing Jiangsu China

This paper studies the longitudinal predictive re-entry guidance law based on the variable universe fuzzy- PI composite control to overcome the inaccuracy of the reference trajectory re-entry guidance for reentry vehicles. The variable universe fuzzy controller is used to obtain a satisfactory dynamic response when the downrange error is large, and the PI controller is utilized to eliminate the steady state error when the downrange error is small. Simulation results show that the proposed guidance law is very robust to the initial errors and can achieve better accuracy, and is also able to handle the effect of the stochastic errors in re-entry processes.

关键词： Re-entry guidance Variable universe Fuzzy control PI control

Online-SVR-compensated nonlinear generalized predictive control for hypersonic vehicles

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2011年第3期54卷 551-562页

作者： CHENG Lu , JIANG Chang Sheng & PU Ming college of automation engineering, nanjing university of aeronautics and astronautics, nanjing 210016, China 1. college of automation engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

This paper is concerned with the problem of hypersonic vehicle (HSV) attitude control system in uncertain flight conditions. The problem can be expressed as the adaptive robust control for a class of uncertain nonlinear systems. Based on the description of the aerodynamic structure and the model of flight control system of a certain kind of HSV, the ideal nonlinear generalized predictive control (NGPC) law based on uncertain nonlinear model is raised first to optimize the receding-horizon criterion of tracking errors. Then the online support vector regression (SVR) is employed to identify the uncertain item in the ideal control law. It is the compensating part of the controller. In addition, the stability of the close-loop system is analyzed using the Lyapunov method. The developed control strategy is well-implemented in this HSV attitude control system, and the simulation results compared with both nominal NGPC and RBF neural network disturbance observer show the good robustness and disturbance attenuation ability of this strategy and demonstrate the efficiency of online SVR algorithm.

关键词： hypersonic vehicle flight control nonlinear generalized predictive control online support vector regression

Resolution method for overlapping peaks based on the fractional-order differential

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2007年第6期50卷 797-805页

作者： LI YuanLu1, YU ShengLin2 & ZHENG Gang2 1 college of Information & Control, nanjing university of Information Science & Technology, nanjing 210044, China 2 college of automation engineering,{5., nanjing 210016, China 1. college of Information & Control Nanjing University of Information Science & Technology Nanjing 210044 China 2. college of automation engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Equations between the differential order and the maximum of the fractional-order differential for the specified peak signals are developed based on the variation of the maximum of the specified peak signals at different orders. Also, equations between the differential order and the zero-crossing of the fractional-order differential of the specified peak signals are proposed according to the variation of the zero-crossing of the specified peak signals at different orders. Characteristic paramters of the Gaus- sian peak, Lorentzian peak, and Tsallis peak can be estimated using estimator I and estimator II which are obtained by the equations above. As a result, a new method is presented to resolve the overlapped peaks signal. Firstly, a fractional-order differential of the specified peak signals is obtained with the fractional-order differentiation filter. Then, characteristic paramters of the specified peak signals can be extracted using estimator I and estimator II. Finally, the Tsallis peak is used as a model to assign the overlapping peak signals correctly. Experimental results show that the proposed method is efficient and effective for the simulated overlapping peaks and detected overlapping voltammetric peak signals.

关键词： fractional-order differentiation filter, fractional-order differential, overlapping peaks, voltammetric peak

An output delay approach to fault estimation for sampled-data systems

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2012年第9期55卷 2128-2138页

作者： WEN ChengLin 1,QIU AiBing 2 & JIANG Bin 3 1 Institute of Information and Control,Hangzhou Dianzi university,Hangzhou 310018,China 2 School of Electrical engineering,Nantong university,Nantong 226019,China 3 college of automation engineering,nanjing university of aeronautics and astronautics,nanjing 210016,China 1. Institute of Information and Control Hangzhou Dianzi University Hangzhou 310018 China2. School of Electrical Engineering Nantong University Nantong 226019 China3. College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The problem of fault estimation for a class of non-uniformly sampled-data systems is investigated from the time delay point of view in this ***,the output delay approach is employed to model the sampled-data system as a continuous-time one with time-varying delay ***,based on the analysis of the inapplicability of the adaptive fault diagnosis observer in such class of time-delay systems,a novel augmented fault estimation observer design method is proposed to guarantee the exponential convergence of the estimation ***,an extension to the case of time varying fault estimation for the noisy sampled-data systems is ***,simulation results of a flight control system are presented to demonstrate the effectiveness of the proposed method.

关键词： fault estimation non-uniformly sampled-data augmented observer output delay

Theoretical Model of Transformation Superlastic Diffusion Bonding for Eutectoid Steel

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

厦门大学学报（自然科学版） 2002年第S1期41卷 13-14页

作者： LU Shi-hong, YUN Jun-bi (college of Mechanic and Electricial engineering, nanjing university of aeronautics &{5., nanjing 210016, China)

Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is mainly described as two-stage process: Ⅰ The interfacial cavity with shape change from diamond to cylinder.Ⅱ The radius of the cylindrical cavity are reduced and eliminated gradually. A new theoretical model is established for the process of transformation superplastic diffusion bonding (TSDB) on the basis of a theoretical model for isothermal superplastic diffusion. The model can predict the bonding quality which is affected by technological parameters, such as limit cycling temperature, the compressive stress, the numbers of thermal cycles and temperature cycling through the phase transformation in the thermal cycling and so on. Results show that the maximum temperature, the compressive stress, the numbers of thermal cycles and the rate of temperature changing speed in the thermal cycling have an important influence on TSDB process. Meanwhile, reasonable technological parameters chosen from theoretical analysis is in good agreement with those obtained from experimental results.

关键词： TSDB eutectoid steel phase transformation superplasticity diffusion bonding theoretical model

Research on Knowledge-based Connecting Elements Modeling

在线全文

学校读者我要写书评

暂无评论

厦门大学学报（自然科学版） 2002年第S1期41卷 162-163页

作者： HUANG Xiang, YAN Chong-jing (college of Mechanical and Electrical engineering, nanjing university o f aeronautics and{5., nanjing 210016, China)

Steps of manipulation is required to complete the m od eling of the connection elements such as bolt, pin and the like in commerce CAD system. It leads to low efficiency, difficulty to assure the relative position, impossibility to express rules and knowledge. Based on the inner character analy sis of interpart, detail modification and assembly relation of mechanical connec ting element, the idea, which extends the feature modeling of part to the interp art feature modeling for assembly purpose, is presented, and virtual part based connecting element modeling is proposed. Virtual part is a complement set of lo cal modification of part to be connected. In assembly modeling, base part is mod ified by Boolean operation between base part and virtual part. The modeling and assembly is finished just in one operation, at the same time the rules and knowl edge of the connection elements are encapsulated through virtual part. According to this mechanism, a knowledge-based connecting elements rapid design module i s developed on commerce software package UG with satisfying results.

关键词： CAD knowledge-based engineering assembly conn ecting element

A Novel Dual-Rate Sampling Switched-Capacitor Configuration and Its Application

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology of China 2003年第1期1卷 74-79页

作者： CAO Kunyong YU Shenglin(college of automation engineering,nanjing university of{5. and astronautics nanjing 210016 China) School of Microelectronics and Solid-state Electronics UESTC Chengdu 610054 China

In order to realize accurate bilinear transformation from s- to z-domain,a novelswitched-capacitor configuration is proposed in the light of principles of dual-rate sampling and chargeconservation,which has also been used for building a 5.h-order elliptic lowpass *** filter issimulated and measured in typical 0.34 μm/3.3 V Si CMOS process models,special full differentialoperational amplifiers and CMOS transfer gate switches,which achieves 80 MHz sampling rate,17.8MHz cutoff frequency,0.05. dB maximum passband ripple,42.1 dB minimum stopband attenuation and74 mW quiescent power *** the same time,the dual-rate sampling topology breaks thetraditional restrictions of filter introduced by unit-gain bandwidth and slew rate of operational amplifiersand also improves effectively their performances in high-frequency *** has been applied forthe design of an anti-alias filter in analog front-end of video decoder IC with 15.MHz signal frequencyyet.

关键词： a novel SC configuration dual-rate sampling 80MSPS 0.34μm Si CMOS switched capacitor filter(SCF)

DYNAMIC RESPONSE OF ROLLER GEAR INDEXING CAM SYSTEM CONSIDERING CLEARANCE AND MOTOR CHARACTERISTIC

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical engineering 2001年第2期14卷 189-192页

作者： Chang Zongyu Civil Aviation college,nanjing university of aeronautics and astronautics Zhang Ce Yang Yuhu Wang Yuxin Tianjin university 南京航空航天大学国内航空学院江苏南京天津大学天津

The dynamic responses of roller gear indexing cam mechanism are investigated .With applying Lagarange equation and Gear method,motion equations of this mechanism including clearance,motor characteristic,torsion flexibility are developed and *** results show that clearance affects primarily the response on turret,and has little effects on the responses on rotary *** the same time,the velocity fluctuation of motor shaft is not serious for the existence of inertia of reducer,and the high frequency of velocity fluctuation of camshaft is related with the torsion stiffness of shaft and the clearance between pairs.

关键词： Roller gear indexing cam mechanism Clearance Motor characteristic Dynamic response

在线全文

学校读者我要写书评

暂无评论

高低温环境下摩擦系数的高准确度测试

数据采集与处理 2004年第1期19卷 111-114页

作者：吴惠祥杨忠毛万华南京航空航天大学航空宇航学院南京210016 南京航空航天大学自动化学院南京210016 南京航空航天大学理学院南京210016

在航空要求的高低温环境下 (-5.5. +1 2 5. ) ,为实现摩擦系数与接触电阻的高准确度测试 ,本文研制了适合于在高低温环境下测试摩擦件摩擦系数与接触电阻的测试试验台。通过对试验件载荷和摩擦力矩的测量 ,测量出试验件在不同温度及... 详细信息

在航空要求的高低温环境下 (-5.5. +1 2 5. ) ,为实现摩擦系数与接触电阻的高准确度测试 ,本文研制了适合于在高低温环境下测试摩擦件摩擦系数与接触电阻的测试试验台。通过对试验件载荷和摩擦力矩的测量 ,测量出试验件在不同温度及不同载荷下的摩擦系数与接触电阻 ,用试验及曲线拟合方法研究并解决了力传感器的温度补偿问题。为提高测试精度 ,对测试系统的硬件和软件进行了抗干扰优化设计 ,通过对某航空产品的试验 ,数据显示测试台的测试精度达 4%。

关键词：机械零部件摩擦系数高准确度测试接触电阻