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| 1 | Linearization method of nonlinear aeroelastic stability for complete aircraft with high-aspect-ratio wings显示文摘A linearization method and an engineering approach for the geometric nonlinear aeroelastic stability analysis of the very flexi- ble aircraft with high-aspect-ratio wings are established based on the little dynamic perturbation assumption.The engineering practicability of the method is validated by a complex example.For a high-altitude long-endurance unmanned aircraft,the nonlinear static deformations under straight flight and the gust loads are calculated.At the corresponding nonlinear equilibrium state,the complete aircraft is linearized dynamically and the vibration modes are calculated considering the large deformation effects.Then the unsteady aerodynamics are calculated by the double lattice method.Finally,the aeroelastic stability of the complete aircraft is analyzed.The results are compared with the traditional linear calculation.The work shows that the geometric nonlinearity induced by the large structural deformation leads to the motion coupling of the wing chordwise bending and the torsion,which changes the mode frequencies and mode shapes.This factors change the aeroelastic coupling relationship of the flexible modes leading to the decrease of the flutter speed.The traditional linear method would give not only an imprecise flutter speed but also a possible dramatic mistake on the stability.Hence,for a high-altitude long-endurance unmanned aircraft with high-aspect-ratio wings,or a similar very flexible aircraft,the geometric nonlinear aeroelastic analysis should be a necessary job in engineering practice. | XIE ChangChuan YANG Chao | 2011 | Science China(Technological Sciences)2011，54，2： | 27 |
| 2 | Static aeroelastic analysis of very flexible wings based on non-planar vortex lattice method显示文摘A rapid and efficient method for static aeroelastic analysis of a flexible slender wing when considering the structural geometric nonlinearity has been developed in this paper. A non-planar vortex lattice method herein is used to compute the non-planar aerodynamics of flexible wings with large deformation. The finite element method is introduced for structural nonlinear statics analysis. The surface spline method is used for structure/aerodynamics coupling. The static aeroelastic characteristics of the wind tunnel model of a flexible wing are studied by the nonlinear method presented, and the nonlinear method is also evaluated by comparing the results with those obtained from two other methods and the wind tunnel test. The results indicate that the traditional linear method of static aeroelastic analysis is not applicable for cases with large deformation because it produces results that are not realistic. However, the nonlinear methodology, which involves combining the structure finite element method with the non-planar vortex lattice method, could be used to solve the aeroelastic deformation with considerable accuracy, which is in fair agreement with the test results. Moreover, the nonlinear finite element method could consider complex structures. The non-planar vortex lattice method has advantages in both the computational accuracy and efficiency. Consequently, the nonlinear method presented is suitable for the rapid and efficient analysis requirements of engineering practice. It could be used in the preliminary stage and also in the detailed stage of aircraft design. | Xie Changchuan Wang Libo Yang Chao Liu Yi | 2013 | Chinese Journal of Aeronautics2013，26，3： | 13 |
| 3 | Theoretic analysis and experiment on aeroelasticity of very flexible wing显示文摘A high-altitude long-endurance aircraft with high-aspect-ratio wing usually generates large deformation,which brings the geometric nonlinear aeroelastic problems.In recent decades,it has become a key focus of the international researchers of aeroelasticity.But some critical technologies are not developed systematically,such as aerodynamic calculation methods of the curved wing with deformation,moreover,there are few experimental validations of these technologies.In this paper,we established the steady aerodynamic calculating method of the curved wing with quite large deformation based on the extended lifting line method,and calculated the unsteady aerodynamics using the strip theory considering curved surface effects.Combining the structure geometrical nonlinear finite element method,we constructed a systematic analytic approach for the static aeroelasticity and flutter of very flexible wing,and further designed the ground vibration and wind tunnel test to verify this approach.Through the test and the theoretic results comparison,we concluded that the extended lifting line method has adaptable precision for the static aeroealsticity and the strip theory considering curved surface effects for flutter analysis can give exact critical speed and flutter mode when the dynamic stall does not happen.The work in this paper shows that the geometric nonlinear aeroelastic analytic approach for very flexible wing has very high efficiency and adaptable precision.It can be used in the engineering applications,especially the iterated design in preliminary stage. | XIE ChangChuan LIU Yi YANG Chao | 2012 | Science China(Technological Sciences)2012，55，9： | 10 |
| 4 | Gust response analysis and wind tunnel test for a high-aspect ratio wing显示文摘A theoretical nonlinear aeroelastic response analysis for a flexible high-aspect ratio wing excited by harmonic gust load is presented along with a companion wind tunnel test. A multidisciplinary coupled numerical calculation is developed to simulate the flexible model wing undergoing gust load in the time domain via discrete nonlinear finite element structural dynamic analysis and nonplanar unsteady vortex lattice aerodynamic computation. A dynamic perturbation analysis about a nonlinear static equilibrium is also used to determine the small perturbation flutter boundary. A novel noncontact 3-D camera measurement analysis system is firstly used in the wind tunnel test to obtain the spatial large deformation and responses. The responses of the flexible wing under different static equilibrium states and frequency gust loads are discussed. The fair to good quantitative agreements between the theoretical and experimental results demonstrate that the presented analysis method is an acceptable way to predict the geometrically nonlinear gust response for flexible wings. | Liu Yi Xie Changchuan Yang Chao Cheng Jialin | 2016 | Chinese Journal of Aeronautics2016，29，1： | 10 |
| 5 | Aeroelastic trim and flight loads analysis of flexible aircraft with large deformations显示文摘A method for static aeroelastic trim analysis and flight loads computation of a flexible aircraft with large deformations has been presented in this paper,which considers the geometric nonlinearity of the structure and the nonplanar effects of aerodynamics.A nonplanar vortex lattice method is used to compute the nonplanar aerodynamics.The nonlinear finite element method is introduced to consider the structural geometric nonlinearity.Moreover,the surface spline method is used for structure/aerodynamics coupling.Finally,by combining the equilibrium equations of rigid motions of the deformed aircraft,the nonlinear trim problem of the flexible aircraft is solved by iterative method.For instance,the longitudinal trim analysis of a flexible aircraft with large-aspect-ratio wings is carried out by both the nonlinear method presented and the linear method of MSC Flightloads.Results obtained by these two methods are compared,and it is indicated that the results agree with each other when the deformation is small.However,because the linear method of static aeroelastic analysis does not consider the nonplanar aerodynamic effects or structural geometric nonlinearity,it is not applicable as the deformations increase.Whereas the nonlinear method presented could solve the trim problem accurately,even the deformations are large,which makes the nonlinear method suitable for rapid and efficient analysis in engineering practice.It could be used not only in the preliminary stage but also in the detail stage of aircraft design. | YANG Chao WANG LiBo XIE ChangChuan LIU Yi | 2012 | Science China(Technological Sciences)2012，55，10： | 10 |
| 6 | RIP1-dependent linear and nonlinear recruitments of caspase-8 and RIP3 respectively to necrosome specify distinct cell death outcomes显示文摘There remains a significant gap in our quantitative understanding of crosstalk between apoptosis and necroptosis pathways.By employing the SWATH-MS technique,we quantified absolute amounts of up to thousands of proteins in dynamic assembling/de-assembling of TNF signaling complexes.Combining SWATH-MS-based network modeling and experimental validation,we found that when RIP1 level is below~1000 molecules/cell(mpc),the cell solely undergoes TRADD-dependent apoptosis.When RIP1 is above~1000 mpc,pro-caspase-8 and RIP3 are recruited to necrosome respectively with linear and nonlinear dependence on RIP1 amount,which well explains the co-occurrence of apoptosis and necroptosis and the paradoxical obser-vations that RIP1 is required for necroptosis but its increase down-regulates necroptosis.Higher amount of RIP1(>~46,000 mpc)suppresses apoptosis,leading to necroptosis alone.The relation between RIP1 level and occurrence of necroptosis or total cell death is biphasic.Our study provides a resource for encoding the com-plexity of TNF signaling and a quantitative picture how distinct dynamic interplay among proteins function as basis sets in signaling complexes,enabling RIP1 to play diverse roles in governing cell fate decisions. | Xiang Li Chuan-Qi Zhong Rui Wu Xiaozheng Xu Zhang-Hua Yang Shaowei Cai Xiurong Wu Xin Chen Zhiyong Yin Qingzu He Dianjie Li Fei Xu Yihua Yan Hong Qi Changchuan Xie Jianwei Shuai Jiahuai Han | 2021 | Protein & Cell2021，12，11： | 5 |
| 7 | Application of output feedback sliding mode control to active flutter suppression of two-dimensional airfoil显示文摘The effectiveness of the sliding mode control(SMC) method for active flutter suppression(AFS) and the issues concerning control system discretization and control input constraints were studied using a typical two-dimensional airfoil.The airfoil has a trailing-edge flap for flutter control.The aeroelastic system involves a two-degrees-of-freedom motion(pitch and plunge),and the equations were constructed by utilizing quasi-steady aerodynamic forces.The control system,designed by the output feedback SMC method,was incorporated to suppress the pitch-plunge flutter.Meanwhile,the system discretization and the flap deflection constraints were implemented.Then,a classical Runge-Kutta(RK) algorithm was utilized for numerical calculations.The results indicated that the close-loop system with the SMC system could be stable at a speed above the flutter boundary.However,when the flap deflection limits are reached,the close-loop system with the simple discretized control system loses control.Furthermore,control compensation developed by theoretical analysis was proposed to make the system stable again.The parameter perturbations and the time delay effects were also discussed in this paper. | YANG Chao,SONG Chen,WU ZhiGang & XIE ChangChuan School of Aeronautic Science and Engineering,Beijing University of Aeronautics & Astronautics,Beijing 100191,China | 2010 | Science China(Technological Sciences)2010，53，5： | 5 |
| 8 | Gust load alleviation wind tunnel tests of a large-aspect-ratio flexible wing with piezoelectric control显示文摘An active control technique utilizing piezoelectric actuators to alleviate gust-response loads of a large-aspect-ratio flexible wing is investigated. Piezoelectric materials have been extensively used for active vibration control of engineering structures. In this paper, piezoelectric materials further attempt to suppress the vibration of the aeroelastic wing caused by gust. The motion equation of the flexible wing with piezoelectric patches is obtained by Hamilton's principle with the modal approach, and then numerical gust responses are analyzed, based on which a gust load alleviation(GLA) control system is proposed. The gust load alleviation system employs classic propor tional-integral-derivative(PID) controllers which treat piezoelectric patches as control actuators and acceleration as the feedback signal. By a numerical method, the control mechanism that piezoelectric actuators can be used to alleviate gust-response loads is also analyzed qualitatively. Furthermore, through low-speed wind tunnel tests, the effectiveness of the gust load alleviation active control technology is validated. The test results agree well with the numerical results. Test results show that at a certain frequency range, the control scheme can effectively alleviate the z and x wingtip accelerations and the root bending moment of the wing to a certain extent. The control system gives satisfying gust load alleviation efficacy with the reduction rate being generally over 20%. | Bi Ying Xie Changchuan An Chao Yang Chao | 2017 | Chinese Journal of Aeronautics2017，30，1： | 5 |
| 9 | Static aeroelastic analysis including geometric nonlinearities based on reduced order model显示文摘This paper describes a method proposed for modeling large deflection of aircraft in nonlinear aeroelastic analysis by developing reduced order model(ROM).The method is applied for solving the static aeroelastic and static aeroelastic trim problems of flexible aircraft containing geometric nonlinearities;meanwhile,the non-planar effects of aerodynamics and follower force effect have been considered.ROMs are computational inexpensive mathematical representations compared to traditional nonlinear finite element method(FEM) especially in aeroelastic solutions.The approach for structure modeling presented here is on the basis of combined modal/finite element(MFE) method that characterizes the stiffness nonlinearities and we apply that structure modeling method as ROM to aeroelastic analysis.Moreover,the non-planar aerodynamic force is computed by the non-planar vortex lattice method(VLM).Structure and aerodynamics can be coupled with the surface spline method.The results show that both of the static aeroelastic analysis and trim analysis of aircraft based on structure ROM can achieve a good agreement compared to analysis based on the FEM and experimental result. | Xie Changchuan An Chao Liu Yi Yang Chao | 2017 | Chinese Journal of Aeronautics2017，30，2： | 5 |
| 10 | Aeroservoelastic stability analysis for flexible aircraft based on a nonlinear coupled dynamic model显示文摘A unified theoretical aeroservoelastic stability analysis framework for flexible aircraft is established in this paper. This linearized state space model for stability analysis is based on nonlinear coupled dynamic equations, in which rigid and elastic motions of aircraft are both considered.The common body coordinate system is utilized as the reference frame in the deduction of dynamic equations, and significant deformations of flexible aircraft are also fully concerned without any excessive assumptions. Therefore, the obtained nonlinear coupled dynamic models can well reflect the special dynamic coupling mechanics of flexible aircraft. For aeroservoelastic stability analysis,the coupled dynamic equations are linearized around the nonlinear equilibrium state and together with a control system model to establish a state space model in the time domain. The methodology in this paper can be easily integrated into the industrial design process and complex structures.Numerical results for a complex flexible aircraft indicate the necessity to consider the nonlinear coupled dynamics and large deformation when dealing with aeroservoelastic stability for flexible aircraft. | Yi LIU Changchuan XIE | 2018 | Chinese Journal of Aeronautics2018，31，12： | 4 |
| 11 | Joint beamforming and scheduling in the downlink of cognitive radio networks显示文摘Cognitive radio has been recently proposed as a promising technology to improve the spectrum utilization. In this paper, we consider a system where a licensed radio spectrum is shared by a primary network and a secondary network. Based on the subspace theory, a novel low-complexity algorithm for secondary user selection has been proposed. On the basis of the scheduling scheme, we jointly consider transmit beamforming, scheduling and power allocation, and subsequently present a complete set of solution for secondary network downlink. Simulation results has shown that our proposed scheme not only can limit the introduced interference at primary users within the tolerable range, but also can achieve high sum-rate throughput of secondary network, simultaneously. Furthermore, as is proved by simulation results, our scheme is very robust due to the fact that only a little tolerable performance drop is introduced when simple but nonoptimal equal power allocation is adopted. | XI Wei YIN ChangChuan YUE GuangXin | 2009 | Science in China(Series F)2009，52，12： | 4 |
| 12 | Conceptual design and flight test of two wingtipdocked multi-body aircraft显示文摘To overcome the drawbacks such as large wing deformations,poor performance encountering gusts,limits in taking off and landing,inconvenience of transportation of High-Altitude Long-Endurance(HALE)Unmanned Aerial Vehicles(UAVs),a new conceptual aircraft called wingtip-docked Multi-Body Aircraft(MBA)has attracted lots of attentions.Aiming to investigate the feasibility of this concept,two UAV models were designed,manufactured and connected by a wingtip-docking mechanism,which only allows the relative roll motion between the two aircraft.The trim solution of the two connected aircraft is firstly obtained by solving the developed nonlinear flight dynamic equations,followed by the stability analysis based on the linearized model.The results show that the connected aircraft is inherently unstable and cannot fly without a reasonable flight control system.A set of Proportional-Integral-Derivative(PID)control laws was then developed and implemented in the two experimental aircraft.The success of the flight tests show that the flight control can effectively eliminate the unstable motion and the wingtip-docked MBA is controllable and feasible。 | Yang MENG Chao AN Changchuan XIE Chao YANG | 2022 | Chinese Journal of Aeronautics2022，35，12： | 3 |
| 13 | Structure and Magnetic Behavior of CoPt Films Prepared on MgO(001) Substrates by dc Plasma Biased Sputtering显示文摘 | Zhongyu Zhao Changchuan Chen | 2004 | Thin Solid Films2004，459，： | 1 |
| 14 | A Preliminary Study on Targets Association Algorithm of Radar and AIS Using BP Neural Network显示文摘 | Hu Xiaorui Lin Changchuan | 2011 | Procedia Engineering2011，，： | 1 |
| 15 | Genetic and Epigenetic Down-regulation of MicroRNA-212 Promotes Colorectal Tumor Metastasis via Dysregulation of MnSOD显示文摘 | Xiangqi Meng Jiangxue Wu Changchuan Pan Hui Wang Xiaofang Ying Yi Zhou Hongyan Yu Yufang Zuo Zhizhong Pan Ran–Yi Liu Wenlin Huang | 2013 | Gastroenterology2013，，2： | 1 |
| 16 | Time-domain nonlinear aeroelastic analysis and wind tunnel test of a flexible wing using strain-based beam formulation显示文摘A theoretical formulation for time-domain nonlinear aeroelastic analysis of a flexible wing model is presented and validated by wind tunnel tests. A strain-based beam model for nonlinear structural analysis is combined with the Unsteady Vortex Lattice Method(UVLM) to form the complete framework for aeroelastic analysis. The nonlinear second-order differential equations are solved by an implicit time integration scheme that incorporates a Newton-Raphson sub-iteration technique. An advanced fiber optic sensing technique is firstly used in a wind tunnel for measuring large structural deformations. In the theoretical study, the nonlinear flutter boundary is determined by analyzing the transient response about the nonlinear static equilibrium with a series of flow velocities. The gust responses of the wing model at various gust frequencies are also studied. Comparisons of the theoretical and experimental results show that the proposed method is suitable for determining the nonlinear flutter boundary and simulating the gust response of flexible wings in the time domain. | Yang MENG Zhiqiang WAN Changchuan XIE Chao AN | 2021 | Chinese Journal of Aeronautics2021，34，1： | 1 |
| 17 | Prediction of protein coding regions by the 3-base periodicity analysis of a DNA sequence显示文摘 | Changchuan Yin Stephen S.-T. Yau | 2007 | Journal of Theoretical Biology2007，，4： | 1 |
| 18 | Scaling laws for overlaid wireless networks:a cognitive radio network versus a primary network显示文摘 | YIN Changchuan GAO Lang | | 0，，04： | 1 |
| 19 | Non-orthogonal pilot pattern for sparse channel estimation in large-scale MIMO-OFDM system显示文摘From the perspective of compressed sensing(CS) theory, the channel estimation problem in large-scale multiple input multiple output(MIMO)-orthogonal frequency division multiplexing(OFDM) system is investigated. According to the theory, the smaller mutual coherence the reconstruction matrix has, the higher success probability the estimation can obtain. Aiming to design a pilot that can make the system reconstruction matrix having the smallest mutual coherence, this paper proposes a low complexity joint algorithm and obtains a kind of non-orthogonal pilot pattern. Simulation results show that compared with the conventional orthogonal pilot pattern, applying the proposed pattern in the CS channel estimation can obtain the better normalized mean square error performance. Moreover, the bit error rate performance of the large-scale MIMO-OFDM system is also improved. | Xu Chao Zhang Jianhua Yin Changchuan | 2016 | The Journal of China Universities of Posts and Telecommunications2016，23，4： | 1 |
| 20 | Development of a Display of the AIS Information 显示文摘 | LIN Changchuan LIN Hai | 2007 | IEEC ICEMI Proceedings2007，，2： | 1 |
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