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84篇 您的检索式:作者名="Youmin Zhang"
    题名 作者 年代 出处 被引量
1A Novel Robust Attitude Control for Quadrotor Aircraft Subject to Actuator Faults and Wind Gusts显示文摘A novel robust fault tolerant controller is developed for the problem of attitude control of a quadrotor aircraft in the presence of actuator faults and wind gusts in this paper.Firstly, a dynamical system of the quadrotor taking into account aerodynamical effects induced by lateral wind and actuator faults is considered using the Newton-Euler approach. Then,based on active disturbance rejection control(ADRC), the fault tolerant controller is proposed to recover faulty system and reject perturbations. The developed controller takes wind gusts,actuator faults and measurement noises as total perturbations which are estimated by improved extended state observer(ESO)and compensated by nonlinear feedback control law. So, the developed robust fault tolerant controller can successfully accomplish the tracking of the desired output values. Finally, some simulation studies are given to illustrate the effectiveness of fault recovery of the proposed scheme and also its ability to attenuate external disturbances that are introduced from environmental causes such as wind gusts and measurement noises.Yuying Guo Bin Jiang Youmin Zhang 2018IEEE/CAA Journal of Automatica Sinica2018,5,1:18
2Spatial patterns of ephemeral plants in Gurbantünggüt Desert显示文摘In the present research,the authors measured parameters of richness,cover and importance value of ephemeral and ephemeroid plants on south-north and east-west transects in the Gurbantünggüt Desert in early spring,and investigated and analyzed the microhabitats,such as terrain,geomorphology,soil physical-chemical properties and crusts. By comparison,the regional differences in the ephemeral distribution in the desert were revealed. The species of ephemeral plants in the south and center are the richest and those in the west are the poorest in the desert. The cover of ephemeral plants in the mid-south is higher than that in the north,and that in the mid-east is higher than that in the west. The response of ephemeral plants to the spatial variation of the desert habitat forms the population-habitat gradient of ephemeral plants. The characteristics are:(1) In the habitat with higher terrain,coarser textured soil with poorer sorting and correspondingly higher organic matter and lower alkali-saline contents,Carex physoides and Eremopyrum orientale are the dominant ephemeral plants;(2) In the dry habitat with lower terrain,looser textured soil,some organic matter,alkali-saline soil,and developed crust,the ephemeral plants Alyssum linifolium and Erodium oxyrrhynchum are of characteristic of drought and alkali-saline tolerance;(3) In the habitat with lower terrain,some water and more alkali-saline soil,the ephemeral plants Neotorularia torulosa and Hypecoum parviflorum being of alkali-saline tolerance are mainly developed. However,most ephemerals are distributed in a habitat order of higher terrain,some organic,and less alkali-saline soil on the above-mentioned ephemeral population-habitat gradient. The spatial gradient of variation in desert microhabitats is small,and as a whole,the physio-logical character of mesophytism is represented by the desert ephemerals.QIAN YiBing WU ZhaoNing ZHANG LiYun ZHAO RuiFeng WANG XiaoYan LI YouMin 2007Chinese Science Bulletin2007,52,22:16
3Adaptive Integral-type Sliding Mode Control for Spacecraft Attitude Maneuvering Under Actuator Stuck Failures显示文摘A fault tolerant control (FTC) design technique against actuator stuck faults is investigated using integral-type sliding mode control (ISMC) with application to spacecraft attitude maneuvering control system. The principle of the proposed FTC scheme is to design an integral-type sliding mode attitude controller using on-line parameter adaptive updating law to compensate for the effects of stuck actuators. This adaptive law also provides both the estimates of the system parameters and external disturbances such that a prior knowledge of the spacecraft inertia or boundedness of disturbances is not required. Moreover, by including the integral feedback term, the designed controller can not only tolerate actuator stuck faults, but also compensate the disturbances with constant components. For the synthesis of controller, the fault time, patterns and values are unknown in advance, as motivated from a practical spacecraft control application. Complete stability and performance analysis are presented and illustrative simulation results of application to a spacecraft show that high precise attitude control with zero steady-error is successfully achieved using various scenarios of stuck failures in actuators.HU Qinglei ZHANG Youmin HUO Xing XIAO Bing 2011Chinese Journal of Aeronautics2011,24,1:15
4Fault-tolerant cooperative control for multiple UAVs based on sliding mode techniques显示文摘This paper proposes a fault-tolerant cooperative control(FTCC) design approach for multiple unmanned aerial vehicles(UAVs), where the outer-loop control and the inner-loop fault accommodation are explicitly considered. The reference signals for the inner-loop of the follower UAV can be directly produced by resorting to a proportional control. In the presence of actuator faults, the estimation of the fault information can be completed within finite time. Moreover, the control of the inner-loop is reconfigured based on the fault information adaptation and sliding mode techniques, such that the deleterious effects due to failed actuators can be compensated within finite time. Simulations of UAV cooperative flight are conducted to illustrate the effectiveness of this FTCC scheme.Peng LI Xiang YU Xiaoyan PENG Zhiqiang ZHENG Youmin ZHANG 2017Science China(Information Sciences)2017,60,7:12
5Novel robust fault diagnosis method for flight control systems显示文摘A novel robust fault diagnosis scheme, which possesses fault estimate capability as well as fault diagnosis property, is proposed. The scheme is developed based on a suitable combination of the adaptive multiple model (AMM) and unknown input observer (UIO). The main idea of the proposed scheme stems from the fact that the actuator Lock-in-Place fault is unknown (when and where the actuator gets locked are unknown), and multiple models are used to describe different fault scenarios, then a bank of unknown input observers are designed to implement the disturbance de-coupling. According to Lyapunov theory, proof of the robustness of the newly developed scheme in the presence of faults and disturbances is derived. Numerical simulation results on an aircraft example show satisfactory performance of the proposed algorithm.Guo Yuying Jiang Bin Zhang Youmin Wang dianfei 2008Journal of Systems Engineering and Electronics2008,19,5:10
6A review on fault-tolerant cooperative control of multiple unmanned aerial vehicles显示文摘This paper presents the recent developments in Fault-Tolerant Cooperative Control(FTCC)of multiple unmanned aerial vehicles(multi-UAVs).To facilitate the analyses of FTCC methods for multi-UAVs.the formation control strategies under fault-free flight conditions of multi-UAVs are first summarized and analyzed,including the leader-following,behavior-based,virtual structure,collision avoidance,algebraic graph-based,and close formation control methods,which are viewed as the cooperative control methods for multi-UAVs at the pre-fault stage.Then,by considering the various faults encountered by the multi-UAVs,the state-of-the-art developments on individual,leader-following,and distributed FTCC schemes for multi-UAVs are reviewed in detail.Finally,conclusions and challenging issues towards future developments are presented.Ziquan YU Youmin ZHANG Bin JIANG Jun FU Ying JIN 2022Chinese Journal of Aeronautics2022,35,1:9
7Progress in ENSO prediction and predictability study显示文摘ENSO is the strongest interannual signal in the global climate system with worldwide climatic, ecological and societal impacts. Over the past decades, the research about ENSO prediction and predictability has attracted broad attention. With the development of coupled models, the improvement in initialization schemes and the progress in theoretical studies, ENSO has become the most predictable climate mode at the time scales from months to seasons. This paper reviews in detail the progress in ENSO predictions and predictability studies achieved in recent years. An emphasis is placed on two fundamental issues: the improvement in practical prediction skills and progress in the theoretical study of the intrinsic predictability limit. The former includes progress in the couple models, data assimilations, ensemble predictions and so on, and the latter focuses on efforts in the study of the optimal error growth and in the estimate of the intrinsic predictability limit.Youmin Tang Rong-Hua Zhang Ting Liu Wansuo Duan Dejian Yang Fei Zheng Hongli Ren Tao Lian Chuan Gao Dake Chen Mu Mu 2018National Science Review2018,5,6:8
8Transplant outcomes of 100 cases of living-donor ABO-incompatible kidney transplantation显示文摘Background:Although ABO-incompatible(ABOi)kidney transplantation(KT)has been performed successfully,a standard preconditioning regimen has not been established.Based on the initial antidonor ABO antibody titers,an individualized preconditioning regimen is developed,and this study explored the efficacy and safety of the regimen.Methods:From September 1,2014,to September 1,2020,we performed 1668 consecutive living-donor KTs,including 100 ABOi and 1568 ABO-compatible(ABOc)KTs.ABOi KT recipients(KTRs)with a lower antibody titer(≤1:8)were administered oral immunosuppressive drugs(OIs)before KT,while patients with a medium titer(1:16)received OIs plus antibody-removal therapy(plasma exchange/double-filtration plasmapheresis),patients with a higher titer(≥1:32)were in addition received rituximab(Rit).Competing risk analyses were conducted to estimate the cumulative incidence of infection,acute rejection(AR),graft loss,and patient death.Results:After propensity score analyses,100 ABOi KTRs and 200 matched ABOc KTRs were selected.There were no significant differences in graft and patient survival between the ABOi and ABOc groups(P=0.787,P=0.386,respectively).After using the individualized preconditioning regimen,ABOi KTRs showed a similar cumulative incidence of AR(10.0%vs.10.5%,P=0.346).Among the ABOi KTRs,the Rit-free group had a similar cumulative incidence of AR(P=0.714)compared to that of the Rittreated group.Multivariate competing risk analyses revealed that a Rit-free regimen reduced the risk of infection(HR:0.31;95%CI:0.12–0.78,P=0.013).Notably,antibody titer rebound was more common in ABOi KTRs receiving a Rit-free preconditioning regimen(P=0.013)than those receiving Rit.ABOi KTRs with antibody titer rebound had a 2.72-fold risk of AR(HR:2.72,95%CI:1.01–7.31,P=0.048).ABOi KTRs had similar serum creatinine and estimated glomerular filtration rate compared to those of ABOc KTRs after the first year.Conclusions:An individualized preconditioning regimen can achieve comparable graft and patient survival rates in ABOi KT with ABOc KT.Rit-free preconditioning effectively prevented AR without increasing the risk of infectious events in those with lower initial titers;however,antibody titer rebound should be monitored.Saifu Yin Qiling Tan Youmin Yang Fan Zhang Turun Song Yu Fan Zhongli Huang Tao Lin Xianding Wang 2022Chinese Medical Journal2022,135,19:7
9Apparent diffusion coefficient in normal and abnormal pattern of intervertebral lumbar discs: initial experience显示文摘The aim of the present study was to compare the relationship of morphologically defined non-bulging/herni-ated, bulging and herniated intervertebral lumbar discs with quantitative apparent diffusion coefficient (ADC). Thirty-two healthy volunteers and 28 patients with back pain or sciatica were examined by MRI. All intervertebral lumbar discs from L1 to S1 were classified according to morphological abnormality and degenerated grades. The ADC values of nucleus pulposus (NP) were measured and recorded. The significant differences about mean ADC values of NP were found between non-bulging/herniated discs and bulging discs as well as herniated discs (P < 0.05), whereas there were no significant differences in ADC values between bulging and herniated discs (P > 0.05). Moreover, statistically significant relationship was found in the mean ADC values of NP between 'non-bulging/herniated and non-degenerated discs' and 'non-bulging/herniated degenerated discs' as well as herniated discs (P < 0.05). Linear regression analysis between ADC value and disc level revealed an inverse correlation (r = -0.18). The ADC map of the NP is a potentially useful tool for the quantitative assessment of componential and molecular alterations accompanied with lumbar disc abnormalities.Gang Niu Xuewen Yu Jian Yang Rong Wang Shaojuan Zhang Youmin Guo 2011The Journal of Biomedical Research2011,25,3:7
10Effect of grain refinement induced by wire and arc additive manufacture (WAAM) on the corrosion behaviors of AZ31 magnesium alloy in NaCl solution显示文摘Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.Jianwei LI Youmin QIU Junjie YANG Yinying SHENG Yanliang YI Xun ZENG Lianxi CHEN Fengliang YIN Jiangzhou SU Tiejun ZHANG Xin TONG Bin GUO 2023Journal of Magnesium and Alloys2023,11,1:6
11New health-state assessment model based on belief rule base with interpretability显示文摘Health-state assessment is the foundation of optimal-maintenance decision-making for complex systems to maintain reliability and safety.Generating the assessment results in a convincing and interpretable way to avoid potential risks is of great importance.Belief rule base(BRB)as an interpretable model performs well in health-state assessment.However,the interpretability of a BRB-based model may be lost during the optimization process,which is expressed mainly as three problems:expert knowledge is not effectively used in the optimization process;the optimized rules of BRB may be in conflict with real systems;and some parameters get over-optimized,which may affect experts’initial judgment.Three concepts—“searching intensity”,“interpretability constraint of belief distribution”,and“rule-activation factor”—are defined to address these problems.Using these concepts,we propose a new health-state assessment model based on the interpretable BRB and a new optimization method to improve the accuracy and preserve the interpretability of the new model.To demonstrate the effectiveness of the proposed model,we conducted an aero-engine case study.Zhijie ZHOU You CAO Guanyu HU Youmin ZHANG Shuaiwen TANG Yuan CHEN 2021Science China(Information Sciences)2021,64,7:6
12Cooperative localization against GPS signal loss in multiple UAVs flight显示文摘Based on multiple unmanned aerial vehicles(UAVs) flight at a constant altitude,a fault-tolerant cooperative localization algorithm against global positioning system(GPS) signal loss due to GPS receiver malfunction is proposed.Contrast to the traditional means with single UAV,the proposed method is based on the use of inter-UAV relative range measurements against GPS signal loss and more suitable for the small-size and low-cost UAV applications.Firstly,for re-localizing an UAV with a malfunction in its GPS receiver,an algorithm which makes use of any other three healthy UAVs in the cooperative flight as the reference points for re-localization is proposed.Secondly,by using the relative ranges from the faulty UAV to the other three UAVs,its horizontal location can be determined after the GPS signal is lost.In order to improve an accuracy of the localization,a Kalman filter is further exploited to provide the estimated location of the UAV with the GPS signal loss.The Kalman filter calculates the variance of observations in terms of horizontal dilution of positioning(HDOP) automatically.Then,during each discrete computing time step,the best reference points are selected adaptively by minimizing the HDOP.Finally,two simulation examples in Matlab/Simulink environment with five UAVs in cooperative flight are shown to evaluate the effectiveness of the proposed method.Yaohong Qu Youmin Zhang 2011Journal of Systems Engineering and Electronics2011,22,1:6
13Multi-model ensemble deep learning method for intelligent fault diagnosis with high-dimensional samples显示文摘Deep learning has achieved much success in mechanical intelligent fault diagnosis in recent years. However, many deep learning methods cannot fully extract fault information to recognize mechanical health states when processing high-dimensional samples. Therefore, a multi-model ensemble deep learning method based on deep convolutional neural network (DCNN) is proposed in this study to accomplish fault recognition of high-dimensional samples. First, several 1D DCNN models with different activation functions are trained through dimension reduction learning to obtain different fault features from high-dimensional samples. Second, the obtained features are constructed into 2D images with multiple channels through a conversion method. The integrated 2D feature images can effectively represent the fault characteristic contained in raw high-dimension vibration signals. Lastly, a 2D DCNN model with multi-layer convolution and pooling is used to automatically learn features from the 2D images and identify the fault mode of the mechanical equipment by adopting a softmax classifier. The proposed method, which is validated using the bearing public dataset of Case Western Reserve University, USA and a one-stage reduction gearbox dataset, has high recognition accuracy. Compared with other classical deep learning methods, the proposed fault diagnosis method has considerable improvements.Xin ZHANG Tao HUANG Bo WU Youmin HU Shuai HUANG Quan ZHOU Xi ZHANG 2021Frontiers of Mechanical Engineering2021,16,2:6
14Design of passive fault-tolerant flight controller against actuator failures显示文摘The problem of designing passive fault-tolerant flight controller is addressed when the normal and faulty cases are prescribed. First of all, the considered fault and fault-free cases are formed by polytopes. As considering that the safety of a post-fault system is directly related to the maximum values of physical variables in the system, peak-to-peak gain is selected to represent the relationships among the amplitudes of actuator outputs, system outputs, and reference commands. Based on the parameter dependent Lyapunov and slack methods, the passive fault-tolerant flight controllers in the absence/presence of system uncertainty for actuator failure cases are designed, respectively. Case studies of an airplane under actuator failures are carried out to validate the effectiveness of the proposedYu Xiang Zhang Youmin 2015Chinese Journal of Aeronautics2015,28,1:4
15A review of progress in coupled ocean-atmosphere model developments for ENSO studies in China显示文摘El Nino-Southern Oscillation(ENSO) is the strongest interannual signal that is producedby basinscale processes in the tropical Pacific,with significant effects on weather and climate worldwide.In the past,extensive and intensive international efforts have been devoted to coupled model developments for ENSO studies.A hierarchy of coupled ocean-atmo sphere models has been formulated;in terms of their complexity,they can be categorized into intermediate coupled models(ICMs),hybrid coupled models(HCMs),and fully coupled general circulation models(CGCMs).ENSO modeling has made significant progress over the past decades,reaching a stage where coupled models can now be used to successfully predict ENSO events 6 months to one year in advance.Meanwhile,ENSO exhibits great diversity and complexity as observed in nature,which still cannot be adequately captured by current state-of-the-art coupled models,presenting a challenge to ENSO modeling.We primarily reviewed the long-term efforts in ENSO modeling continually and steadily made at different institutions in China;some selected representative examples are presented here to review the current status of ENSO model developments and applications,which have been actively pursued with noticeable progress being made recently.As ENSO simulations are very sensitive to model formulations and process representations etc.,dedicated efforts have been devoted to ENSO model developments and improvements.Now,different ocean-atmosphere coupled models have been available in China,which exhibit good model performances and have already had a variety of applications to climate modeling,including the Coupled Model Intercomparison Project Phase 6(CMIP6).Nevertheless,large biases and uncertainties still exist in ENSO simulations and predictions,and there are clear rooms for their improvements,which are still an active area of researches and applications.Here,model performances of ENSO simulations are assessed in terms of advantages and disadvantages with these differently formulated coupled models,pinpointing to the areas where they need to be further improved for ENSO studies.These analyses provide valuable guidance for future improvements in ENSO simulations and predictions.ZHANG Rong-Hua YU Yongqiang SONG Zhenya REN Hong-Li TANG Youmin QIAO Fangli WU Tongwen GAO Chuan HU Junya TIAN Feng ZHU Yuchao CHEN Lin LIU Hailong LIN Pengfei WU Fanghua WANG Lin 2020Journal of Oceanology and Limnology2020,38,4:4
16PID-type fault-tolerant prescribed performance control of fixed-wing UAV显示文摘This paper introduces a fault-tolerant control(FTC)design for a faulty fixed-wing unmanned aerial vehicle(UAV).To constrain tracking errors against actuator faults,error constraint inequalities are first transformed to a new set of variables based on prescribed performance functions.Then,the commonly used and powerful proportional-integral-derivative(PID)control concept is employed to filter the transformed error variables.To handle the fault-induced nonlinear terms,a composite learning algorithm consisting of neural network and disturbance observer is incorporated for increasing flight safety.It is shown by Lyapunov stability analysis that the tracking errors are strictly constrained within the specified error bounds.Experimental results are presented to verify the feasibility of the developed FTC scheme.YU Ziquan ZHANG Youmin JIANG Bin 2021Journal of Systems Engineering and Electronics2021,32,5:3
17Flocking control of a fleet of unmanned aerial vehicles显示文摘Adel BELKADI Zhixiang LIU Laurent CIARLETTA Youmin ZHANG Didier THEILLIOL 2018Control Theory and Technology2018,16,2:3
18Comparison and combination of EAKF and SIR-PF in the Bayesian filter framework显示文摘Bayesian estimation theory provides a general approach for the state estimate of linear or nonlinear and Gaussian or non-Gaussian systems. In this study, we first explore two Bayesian-based methods: ensemble adjustment Kalman filter(EAKF) and sequential importance resampling particle filter(SIR-PF), using a well-known nonlinear and non-Gaussian model(Lorenz '63 model). The EAKF, which is a deterministic scheme of the ensemble Kalman filter(En KF), performs better than the classical(stochastic) En KF in a general framework. Comparison between the SIR-PF and the EAKF reveals that the former outperforms the latter if ensemble size is so large that can avoid the filter degeneracy, and vice versa. The impact of the probability density functions and effective ensemble sizes on assimilation performances are also explored. On the basis of comparisons between the SIR-PF and the EAKF, a mixture filter, called ensemble adjustment Kalman particle filter(EAKPF), is proposed to combine their both merits. Similar to the ensemble Kalman particle filter, which combines the stochastic En KF and SIR-PF analysis schemes with a tuning parameter, the new mixture filter essentially provides a continuous interpolation between the EAKF and SIR-PF. The same Lorenz '63 model is used as a testbed, showing that the EAKPF is able to overcome filter degeneracy while maintaining the non-Gaussian nature, and performs better than the EAKF given limited ensemble size.SHEN Zheqi ZHANG Xiangming TANG Youmin 2016Acta Oceanologica Sinica2016,35,3:3
19Path Following Control for UAV Using Deep Reinforcement Learning Approach显示文摘Unmanned aerial vehicles(UAVs)have been extensively used in civil and industrial applications due to the rapid development of the guidance,navigation and control(GNC)technologies.Especially,using deep reinforcement learning methods for motion control acquires a major progress recently,since deep Q-learning algorithm has been successfully applied to the continuous action domain problem.This paper proposes an improved deep deterministic policy gradient(DDPG)algorithm for path following control problem of UAV.A speci-c reward function is designed for minimizing the cross-track error of the path following problem.In the training phase,a double experience replay bu®er(DERB)is used to increase the learning e±ciency and accelerate the convergence speed.First,the model of UAV path following problem has been established.After that,the framework of DDPG algorithm is constructed.Then the state space,action space and reward function of the UAV path following algorithm are designed.DERB is proposed to accelerate the training phase.Finally,simulation results are carried out to show the e®ectiveness of the proposed DERB–DDPG method.Yintao Zhang Youmin Zhang Ziquan Yu 2021Guidance, Navigation and Control2021,1,1:2
20A Composite Adaptive Fault-Tolerant Attitude Control for a Quadrotor UAV with Multiple Uncertainties显示文摘In this paper,a composite adaptive fault-tolerant control strategy is proposed for a quadrotor unmanned aerial vehicle(UAV)to simultaneously compensate actuator faults,model uncertainties and external disturbances.By assuming knowledge of the bounds on external disturbances,a baseline sliding mode control is first designed to achieve the desired system tracking performance and retain insensitive to disturbances.Then,regarding actuator faults and model uncertainties of the quadrotor UAV,neural adaptive control schemes are constructed and incorporated into the baseline sliding mode control to deal with them.Moreover,in terms of unknown external disturbances,a disturbance observer is designed and synthesized with the control law to further improve the robustness of the proposed control strategy.Finally,a series of comparative simulation tests are conducted to validate the effectiveness of the proposed control strategy where a quadrotor UAV is subject to inertial moment variations and different level of actuator faults.The capabilities and advantages of the proposed control strategy are confirmed and verified by simulation results.WANG Ban ZHANG Youmin ZHANG Wei 2022Journal of Systems Science & Complexity2022,35,1:2
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