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Dynamic flight stability of a model dronefly in vertical flight 被引量:1
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作者 Chong Shen Mao Sun 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第6期828-838,共11页
The dynamic flight stability of a model dronefly in hovering and upward flight is studied.The method of computational fluid dynamics is used to compute the stability derivatives and the techniques of eigenvalue and ei... The dynamic flight stability of a model dronefly in hovering and upward flight is studied.The method of computational fluid dynamics is used to compute the stability derivatives and the techniques of eigenvalue and eigenvector used to solve the equations of motion.The major finding is as following.Hovering flight of the model dronefly is unstable because of the existence of an unstable longitudinal and an unstable lateral natural mode of motion.Upward flight of the insect is also unstable,and the instability increases as the upward flight speed increases.Inertial force generated by the upward flight velocity coupled with the disturbance in pitching angular velocity is responsible for the enhancement of the instability. 展开更多
关键词 Insect vertical flight Flight stability Natural modes of motion
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Fixed-Time Sliding Mode Control With Varying Exponent Coefficient for Modular Reconfigurable Flight Arrays
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作者 Jianquan Yang Chunxi Yang +1 位作者 Xiufeng Zhang Jing Na 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第2期514-528,共15页
The modular system can change its physical structure by self-assembly and self-disassembly between modules to dynamically adapt to task and environmental requirements. Recognizing the adaptive capability of modular sy... The modular system can change its physical structure by self-assembly and self-disassembly between modules to dynamically adapt to task and environmental requirements. Recognizing the adaptive capability of modular systems, we introduce a modular reconfigurable flight array(MRFA) to pursue a multifunction aircraft fitting for diverse tasks and requirements,and investigate the attitude control and the control allocation problem by using the modular reconfigurable flight array as a platform. First, considering the variable and irregular topological configuration of the modular array, a center-of-mass-independent flight array dynamics model is proposed to allow control allocation under over-actuated situations. Secondly, in order to meet the stable, fast and accurate attitude tracking performance of the MRFA, a fixed-time convergent sliding mode controller with state-dependent variable exponent coefficients is proposed to ensure fast convergence rate both away from and near the system equilibrium point without encountering the singularity. It is shown that the controller also has fixed-time convergent characteristics even in the presence of external disturbances. Finally,simulation results are provided to demonstrate the effectiveness of the proposed modeling and control strategies. 展开更多
关键词 Control allocation dynamic model fixed-time stabilization modular reconfigurable flight array(MRFA) sliding mode
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An Overview of the Achievements of Modern Research on the Flying Shadow Pavilion Pictorial
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作者 CHEN Honghui 《Cultural and Religious Studies》 2024年第2期118-122,共5页
The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Z... The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Zhai Pictorial terms of both content and form,and which was founded by the Haiist painter Wu Youru in 1890 in order to reward the increasing number of admirers,but it is still in the initial stage.Flying Shadow Pavilion Pictorial consisted of four parts:pictures of ladies in Shanghai costumes,news about current affairs,pictures of animals,and compilations of women,each of which was accompanied by the then popular notebooks,which were popular at the time among the then readers because of the matching of pictures with text and the mixing of narratives and discussions.This paper takes Flying Shadow Pavilion Pictorial as the main object,summarizes the existing literature about Flying Shadow Pavilion Pictorial,points out the deficiencies of the current research on this basis,and points out the development trend of Flying Shadow Pavilion Pictorial in the future research. 展开更多
关键词 flying Shadow Pavilion Pictorial Dian Shi Zhai Pictorial Late Qing Dynasty’s pictorial
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Research on Online-Offline Hybrid Teaching Mode of College English in the Context of New Liberal Arts
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作者 Qian Li 《Journal of Contemporary Educational Research》 2024年第7期229-233,共5页
English is an important course in colleges,and students’proficiency in the language can significantly affect their learning in multiple disciplines.At present,offline classroom teaching is still the primary mode of c... English is an important course in colleges,and students’proficiency in the language can significantly affect their learning in multiple disciplines.At present,offline classroom teaching is still the primary mode of college English teaching,and online teaching has not been widely used.Under the background of new liberal arts,the teaching tasks and objectives of college English have changed,and it is imperative to carry out online-offline hybrid teaching mode.This paper analyzes the feasibility of the online-offline hybrid teaching mode of college English,summarizes its problems,and explores its implementation strategies in the context of the new liberal arts,to provide references for teachers. 展开更多
关键词 New liberal arts background College English Online-offline hybrid teaching mode
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Research on the Blended Online and Offline Teaching Mode of Ideological and Political Courses in Universities
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作者 WANG Na 《Journalism and Mass Communication》 2024年第1期23-26,共4页
With the development of information technology,the blended online and offline teaching mode has gradually become a new trend in the teaching of ideological and political theory courses in universities.This article ana... With the development of information technology,the blended online and offline teaching mode has gradually become a new trend in the teaching of ideological and political theory courses in universities.This article analyzes the current situation and existing problems of blended online and offline teaching of ideological and political courses in universities,and explores how to effectively combine online and offline teaching resources to improve the teaching effectiveness of ideological and political courses in universities. 展开更多
关键词 ideological and political courses mixed online and offline teaching mode
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Analysis of the Application Value of Virtual Reality Combined with Flipped Classroom Teaching Mode in Cardiopulmonary Resuscitation Teaching
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作者 Hua Liu 《Journal of Contemporary Educational Research》 2024年第5期154-159,共6页
Objective:To analyze the value of using virtual reality combined with the flipped classroom teaching model in teaching cardiopulmonary resuscitation(CPR).Methods:Two classes of our nursing program were randomly select... Objective:To analyze the value of using virtual reality combined with the flipped classroom teaching model in teaching cardiopulmonary resuscitation(CPR).Methods:Two classes of our nursing program were randomly selected for the study from September 2022 to September 2023,Class A(52 students,conventional teaching method)and Class B(52 students,virtual reality combined with flipped classroom teaching mode).The assessment scores and independent learning ability scores of the students in the two classes were compared.Results:CPR theory and operation scores,passing rate,and independent learning ability scores of Class B were higher than those of Class A(P<0.05).Conclusion:the use of virtual reality combined with the flipped classroom teaching mode in CPR teaching is conducive to the improvement of students’assessment scores and independent learning ability. 展开更多
关键词 Virtual reality Flipped classroom teaching mode Cardiopulmonary resuscitation Assessment performance Independent learning ability
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基于Modelsim FLI接口的FPGA仿真技术 被引量:6
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作者 胡军强 李津生 洪佩琳 《电子技术应用》 北大核心 2002年第7期75-77,共3页
介绍了如何利用modelsim提供的FLI(ForeignLanguageInterface)接口对VHDL设计文件进行协同仿真,给出了协同仿真的意义以及协同仿真的程序结构和系统结构。
关键词 modeLSIM FLI接口 FPGA 仿真软件 协同仿真 VHDL设计 C语言
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Analysis on Suitable Distribution Area of Oriental Fruit Fly (Bactrocera dorsalis) Based on GARP Ecological Niche Model
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作者 刘建宏 熊小真 +2 位作者 杨丽英 熊忠平 潘涌智 《Plant Diseases and Pests》 CAS 2010年第6期34-38,共5页
[Objective] The paper was to provide the scientific basis for effective monitoring and early warning on oriental fruit fly in Jiangxi Province.[Method] Using the distribution data and environmental factor data of orie... [Objective] The paper was to provide the scientific basis for effective monitoring and early warning on oriental fruit fly in Jiangxi Province.[Method] Using the distribution data and environmental factor data of oriental fruit fly,the potential distribution area of oriental fruit fly in Jiangxi Province was predicted by GARP ecological niche model.[Result]The total suitable area for oriental fruit fly in Jiangxi province was over two thirds of the whole province.Most areas in southern Jiangxi basin ranged from 24° to 26° N were the high suitable area for oriental fruit fly,where the annual average temperature was 19-20℃.Part areas in north Ganzhou and small areas in southwest Ji'an,Wuzhou,Yingtan,southeast Shangrao ranged from 26° to 27° N were the moderate suitable areas for oriental fruit fly,where the annual average temperature was 18-19℃.The low suitable area was ranged from 26° to 30° N including Binhu,Ganjiang River,Wuhe,Yuanshui area and Southwestern Mountain of Jiangxi Province,where the annual average temperature was 17-18℃.Northeast and northwest areas in Jiangxi Province and coastal areas along the Yangtze River was predicted to be non-suitable area for oriental fruit fly,where the annual average temperature was 16-17℃.[Conclusion] The results showed that the actual distribution of oriental fruit fly basically was consistent with the distribution predicted by GARP. 展开更多
关键词 Oriental fruit fly GARP Potential distribution area JIANGXI
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Analysis of the Teaching Mode of College English Reading Teaching Based on Flipped Classroom Model
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作者 刘娇 《海外英语》 2021年第17期293-294,共2页
With the continuous development of the times, people’s thinking is constantly improving, and the importance of educa-tion is also increasing. As many new teaching models are emerging, the network course education rep... With the continuous development of the times, people’s thinking is constantly improving, and the importance of educa-tion is also increasing. As many new teaching models are emerging, the network course education represented by flipped classroomand MOOC education are increasingly attracting the attention of all walks of life with its unique advantages. The teaching of Eng-lish reading is a key point in College English education. However, the reality of College English reading education is not satisfacto-ry due to certain factors. This paper aims to discuss the implication of flipped classroom mode in college English reading teaching,hoping to provide references for the relevant parties. 展开更多
关键词 Flipped Classroom mode College English Reading Teaching Educational practice
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Robust Adaptive Gain Higher Order Sliding Mode Observer Based Control-constrained Nonlinear Model Predictive Control for Spacecraft Formation Flying 被引量:9
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作者 Ranjith Ravindranathan Nair Laxmidhar Behera 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2018年第1期367-381,共15页
This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher... This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher order sliding mode observer has been proposed to estimate the velocity as well as unmeasured disturbances from the noisy position measurements.A differentiator structure containing the Lipschitz constant and Lebesgue measurable control input, is utilized for obtaining the estimates. Adaptive tuning algorithms are derived based on Lyapunov stability theory, for updating the observer gains,which will give enough flexibility in the choice of initial estimates.Moreover, it may help to cope with unexpected state jerks. The trajectory tracking problem is formulated as a finite horizon optimal control problem, which is solved online. The control constraints are incorporated by using a nonquadratic performance functional. An adaptive update law has been derived for tuning the step size in the optimization algorithm, which may help to improve the convergence speed. Moreover, it is an attractive alternative to the heuristic choice of step size for diverse operating conditions. The disturbance as well as state estimates from the higher order sliding mode observer are utilized by the plant output prediction model, which will improve the overall performance of the controller. The nonlinear dynamics defined in leader fixed Euler-Hill frame has been considered for the present work and the reference trajectories are generated using Hill-Clohessy-Wiltshire equations of unperturbed motion. The simulation results based on rigorous perturbation analysis are presented to confirm the robustness of the proposed approach. 展开更多
关键词 Adaptive gain higher order sliding mode observer leader-follower formation nonlinear model predictive control spacecraft formation flying tracking control
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High-order sliding mode attitude controller design for reentry flight 被引量:7
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作者 Liang Wang Yongzhi Sheng Xiangdong Liu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第5期848-858,共11页
A novel high-order sliding mode control strategy is proposed for the attitude control problem of reentry vehicles in the presence of parametric uncertainties and external disturbances, which results in the robust and ... A novel high-order sliding mode control strategy is proposed for the attitude control problem of reentry vehicles in the presence of parametric uncertainties and external disturbances, which results in the robust and accurate tracking of the aerodynamic angle commands with the finite time convergence. The proposed control strategy is developed on the basis of integral sliding mode philosophy, which combines conventional sliding mode control and a linear quadratic regulator over a finite time interval with a free-final-state and allows the finite-time establishment of a high-order sliding mode. Firstly, a second-order sliding mode attitude controller is designed in the proposed high-order siding mode control framework. Then, to address the control chattering problem, a virtual control is introduced in the control design and hence a third-order sliding mode attitude controller is developed, leading to the chattering reduction as well as the control accuracy improvement. Finally, simulation examples are given to illustrate the effectiveness of the theoretical results. 展开更多
关键词 reentry vehicle attitude control high-order sliding mode control integral sliding mode.
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Sliding Mode Controller Design for Position and Speed Control of Flight Simulator Servo System with Large Friction 被引量:21
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作者 Liu Jinkun & Er LianjieAutomatic Control Department, Beijing University of Aeronautics and Astronautics, Beijing 100083, P. R. China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2003年第3期59-62,共4页
Flight simulator is an important device and a typical high-performance position and speed servo system used in the hardware-in-the-loop simulation of flight control system. Friction is the main nonlinear resistance in... Flight simulator is an important device and a typical high-performance position and speed servo system used in the hardware-in-the-loop simulation of flight control system. Friction is the main nonlinear resistance in the flight simulator servo system, especially in a low-speed state. Based on the description of dynamic and static models of a nonlinear Stribeck friction model, this paper puts forward sliding mode controller to overcome the friction, whose stability is 展开更多
关键词 Sliding mode control Flight simulator Servo system Friction model.
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Investigation of Microstructure, Natural Frequencies and Vibration Modes of Dragonfly Wing 被引量:14
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作者 H. Rajabi M. Moghadami A. Darvizeh 《Journal of Bionic Engineering》 SCIE EI CSCD 2011年第2期165-173,共9页
In the present work, a thorough investigation on the microstructural and morphological aspects of dragonfly wings was carried out using scanning electron microscope. Then, based on this study and the previous reports,... In the present work, a thorough investigation on the microstructural and morphological aspects of dragonfly wings was carried out using scanning electron microscope. Then, based on this study and the previous reports, a precise three-dimensional numerical model was developed and natural frequencies and vibration modes of dragonfly forewing were determined by finite element method. The results shown that dragonfly wings are made of a series of adaptive materials, which form a very complex composite structure. This bio-composite fabrication has some unique features and potential benefits. Furthermore, the numerical results show that the first natural frequency of dragonfly wings is about 168 Hz and bending is the predominant deformation mode in this stage. The accuracy of the present analysis is verified by comparison of calculated results with experimental data. This paper may be helpful for micro aerial vehicle design concerning dynamic response. 展开更多
关键词 insect wing natural frequency vibration mode SEM finite element method
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FUZZY GLOBAL SLIDING MODE CONTROL BASED ON GENETIC ALGORITHM AND ITS APPLICATION FOR FLIGHT SIMULATOR SERVO SYSTEM 被引量:14
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作者 LIU Jinkun HE Yuzhu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2007年第3期13-17,共5页
To alleviate the chattering problem, a new type of fuzzy global sliding mode controller (FGSMC) is presented. In this controller, the switching gain is estimated by fuzzy logic system based on the reachable conditio... To alleviate the chattering problem, a new type of fuzzy global sliding mode controller (FGSMC) is presented. In this controller, the switching gain is estimated by fuzzy logic system based on the reachable conditions of sliding mode controller(SMC), and genetic algorithm (GA) is used to optimize scaling factor of the switching gain, thus the switch chattering of SMC can be alleviated. Moreover, global sliding mode is realized by designing an exponential dynamic sliding surface. Simulation and real-time application for flight simulator servo system with Lugre friction are given to indicate that the proposed controller can guarantee high robust performance all the time and can alleviate chattering phenomenon effectively. 展开更多
关键词 Sliding mode control Chattering free Fuzzy control Genetic algorithm Flight simulator
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Dynamic flight stability of a hovering model insect:lateral motion 被引量:17
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作者 Yanlai Zhang Mao Sun 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第2期175-190,共16页
The lateral dynamic flight stability of a hovering model insect (dronefly) was studied using the method of computational fluid dynamics to compute the stability derivatives and the techniques of eigenvalue and eigen... The lateral dynamic flight stability of a hovering model insect (dronefly) was studied using the method of computational fluid dynamics to compute the stability derivatives and the techniques of eigenvalue and eigenvector analysis for solving the equations of motion. The main results are as following. (i) Three natural modes of motion were identified: one unstable slow divergence mode (mode 1), one stable slow oscillatory mode (mode 2), and one stable fast subsidence mode (mode 3). Modes 1 and 2 mainly consist of a rotation about the horizontal longitudinal axis (x-axis) and a side translation; mode 3 mainly consists of a rotation about the x-axis and a rotation about the vertical axis. (ii) Approximate analytical expressions of the eigenvalues are derived, which give physical insight into the genesis of the natural modes of motion. (iii) For the unstable divergence mode, td, the time for initial disturbances to double, is about 9 times the wingbeat period (the longitudinal motion of the model insect was shown to be also unstable and td of the longitudinal unstable mode is about 14 times the wingbeat period). Thus, although the flight is not dynamically stable, the instability does not grow very fast and the insect has enough time to control its wing motion to suppress the disturbances. 展开更多
关键词 INSECT Dynamic flight stability Hovering ·Lateral motion Natural modes of motion
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Nominal Model-Based Sliding Mode Control with Backstepping for 3-Axis Flight Table 被引量:11
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作者 刘金琨 孙富春 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2006年第1期65-71,共7页
Based on nominal model, a novel global sliding mode controller (GSMC) with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is th... Based on nominal model, a novel global sliding mode controller (GSMC) with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is the global sliding mode controller for practical plant, the other is the integral backstepping controller for nominal model. Modeling error between practical plant and nominal model is used to design GSMC. The steady-state control accuracy can be guaranteed by the integral backstepping control law, and the global robustness can be obtained by GSMC. The stability of the proposed controller is proved according to the Lyapunov approach. The simulation results both of sine signal and step signal tracking for 3-axis flight table are investigated to show good position tracking performance and high robustness with respect to large and parameter changes over all the response time. 展开更多
关键词 nominal model sliding mode control backstepping control robust control 3-axis flight table
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MINTEQ modeling for evaluating the leaching behavior of heavy metals in MSWI fly ash 被引量:12
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作者 Mang Yan Jiang Jianguo Chen Maozhe 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2008年第11期1398-1402,共5页
At present,all kinds of municipal solid waste incineration (MSWI) fly ash stabilization technology has been reported and successfully applied in many countries.However,leaching procedures are very different that the t... At present,all kinds of municipal solid waste incineration (MSWI) fly ash stabilization technology has been reported and successfully applied in many countries.However,leaching procedures are very different that the technologies lack uniform standard,and it is even impossible to predict the long-term stabilization.Geochemical model can explain the environmental stabilization based on chemical phase and thermodynamic crystal structure,and it is also able to guide the development of environment-friendly stabi... 展开更多
关键词 MINTEQ model incinerator fly ash stabilization mechanism
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Flight control for a flexible air-breathing hypersonic vehicle based on quasi-continuous high-order sliding mode 被引量:15
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作者 Jie Wang Qun Zong +1 位作者 Bailing Tian Helong Liu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2013年第2期288-295,共8页
The focus of this paper is on control design and simulation for the longitudinal model of a flexible air-breathing hypersonic vehicle(FAHV).The model of interest includes flexibility effects and intricate couplings ... The focus of this paper is on control design and simulation for the longitudinal model of a flexible air-breathing hypersonic vehicle(FAHV).The model of interest includes flexibility effects and intricate couplings between the engine dynamics and flight dynamics.To overcome the analytical intractability of this model,a nominal control-oriented model is constructed for the purpose of feedback control design in the first place.Secondly,the multi-input multi-output(MIMO) quasi-continuous high-order sliding mode(HOSM) controller is proposed to track step changes in velocity and altitude,which is based on full state feedback.The simulation results are presented to verify the effectiveness of the proposed control strategy. 展开更多
关键词 flexible air-breathing hypersonic vehicle nonlinear robust controller high order sliding mode control output tracking control
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An adaptive backstepping sliding mode method for flight attitude of quadrotor UAVs 被引量:16
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作者 JIANG Xue-ying SU Cheng-li +3 位作者 XU Ya-peng LIU Kai SHI Hui-yuan LI Ping 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第3期616-631,共16页
To overcome nonlinear and 6-DOF(degrees of freedom)under-actuated problems for the attitude and position of quadrotor UAVs,an adaptive backstepping sliding mode method for flight attitude of quadrotor UAVs is proposed... To overcome nonlinear and 6-DOF(degrees of freedom)under-actuated problems for the attitude and position of quadrotor UAVs,an adaptive backstepping sliding mode method for flight attitude of quadrotor UAVs is proposed,in which an adaptive law is designed to online estimate the parameter variations and the upper bound of external disturbances and the assessments is utilized to compensate the backstepping sliding mode control.In addition,the tracking error of the design method is shown to asymptotically converge to zero by using Lyapunov theory.Finally,based on the numerical simulation of quadrotor UAVs using the setting parameters,the results show that the proposed control approach can stabilize the attitude and has hover flight capabilities under the parameter perturbations and external disturbances. 展开更多
关键词 quadrotor UAVs adaptive backstepping sliding mode adaptive law tracking error
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Characterization and mode of occurrence of rare earth elements and yttrium in fly and bottom ash from coal-fired power plants in Java,Indonesia 被引量:2
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作者 Dea Anisa Ayu Besari Ferian Anggara +1 位作者 Widya Rosita Himawan T.B.M.Petrus 《International Journal of Coal Science & Technology》 EI CAS CSCD 2022年第2期229-244,共16页
Fly and bottom ash(FABA)produced primarily from coal combustion in a coal-fred power plant consists of fne particles of the organic and inorganic mixture and trace elements.Eight FABA samples from coal-fred power plan... Fly and bottom ash(FABA)produced primarily from coal combustion in a coal-fred power plant consists of fne particles of the organic and inorganic mixture and trace elements.Eight FABA samples from coal-fred power plants in Java,Indonesia,had been collected for composition and rare earth element and Yttrium(REY)mode of occurrence identifcation.The geochemical composition of both major and trace elements was determined by inductively coupled plasma-mass spectrometry/atomic emission spectrometry(ICP-MS/AES).Furthermore,the composition of FABA was identifed by petrography with refected light microscopy and X-ray difraction(XRD)analysis.Simultaneously,scanning electron microscope determines the mode of occurrence of REY with an energy-dispersive X-ray(SEM–EDX).The study fnds that the inorganic component of FABA consists of glass,Fe–Mg spinel,mullite,quartz,Fe-oxide mineral,and K-feldspar.In contrast,the organic component is dominated by unburned coal.Glass is the most abundant component with cenospheres as major and pleiospheres as minor constituents.Trace elements analysis indicates REY concentration with heavy REY(HREY)distribution pattern.Moreover,SEM–EDX analysis results show that Yttrium(Y)occurs in glass and has a low concentration in spinel.From the mode occurrence of REY,in particular Yttrium,it can be predicted that alkaline fusion followed by acid leaching will be the most appropriate extraction method to extract REY from Indonesian FABA. 展开更多
关键词 REY fly ash Bottom ash GLASS Indonesia
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