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| 1 | A 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 | 2018 | IEEE/CAA Journal of Automatica Sinica2018，5，1： | 18 |
| 2 | Spatial 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 | 2007 | Chinese Science Bulletin2007，52，22： | 16 |
| 3 | Adaptive 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 | 2011 | Chinese Journal of Aeronautics2011，24，1： | 15 |
| 4 | Quantitative computed tomography analysis for stratifying the severity of Coronavirus Disease 2019显示文摘To examine the feasibility of using a computer tool for stratifying the severity of Coronavirus Disease 2019(COVID-19)based on computed tomography(CT)images.We retrospectively examined 44 confirmed COVID-19 cases.All cases were evaluated separately by radiologists(visually)and through an in-house computer software.The degree of lesions was visually scored by the radiologist,as follows,for each of the 5 lung lobes:0,no lesion present;1,<1/3 involvement;2,>1/3 and<2/3 involvement;and 3,>2/3 involvement.Lesion density was assessed based on the proportion of ground-glass opacity(GGO),consolidation and fibrosis of the lesions.The parameters obtained using the computer tool included lung volume(mL),lesion volume(mL),lesion percentage(%),and mean lesion density(HU)of the whole lung,right lung,left lung,and each lobe.The scores obtained by the radiologists and quantitative results generated by the computer software were tested for correlation.A Chi-square test was used to test the consistency of radiologist-and computer-derived lesion percentage in the right/left lung,upper/lower lobe,and each of the 5 lobes.The results showed a strong to moderate correlation between lesion percentage scores obtained by radiologists and the computer software(r ranged from 0.7679 to 0.8373,P<0.05),and a moderate correlation between the proportion of GGO and mean lesion density(r=-0.5894,P<0.05),and proportion of consolidation and mean lesion density(r=0.6282,P<0.05).Computer-aided quantification showed a statistical significant higher lesion percentage for lower lobes than that assessed by the radiologists(x^2=8.160,P=0.004).Our experiments demonstrated that the computer tool could reliably and accurately assess the severity and distribution of pneumonia on CT scans. | Cong Shen Nan Yu Shubo Cai Jie Zhou Jiexin Sheng Kang Liu Heping Zhou Youmin Guo Gang Niu | 2020 | Journal of Pharmaceutical Analysis2020，10，2： | 13 |
| 5 | Fault-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 | 2017 | Science China(Information Sciences)2017，60，7： | 12 |
| 6 | Novel 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 | 2008 | Journal of Systems Engineering and Electronics2008，19，5： | 10 |
| 7 | Genesis of the 2014–2016 El Nio events显示文摘The 2015/2016 El Nio was one of the strongest El Nio events in history, and this strong event was preceded by a weak El Nio in 2014. This study systematically analyzed the dynamical processes responsible for the genesis of these events. It was found that the weak 2014 El Nio had two warming phases, the spring-summer warming was produced by zonal advection and downwelling Kelvin waves driven by westerly wind bursts(WWBs), and the autumn-winter warming was produced by meridional advection, surface heating as well as downwelling Kelvin waves. The 2015/2016 extreme El Nio, on the other hand, was primarily a result of sustained zonal advection and downwelling Kelvin waves driven by a series of WWBs, with enhancement from the Bjerknes positive feedback. The vast difference between these two El Nio events mainly came from the different amount of WWBs in 2014 and 2015. As compared to the 1982/1983 and 1997/1998 extreme El Nio events, the 2015/2016 El Nio exhibited some distinctive characteristics in its genesis and spatial pattern. We need to include the effects of WWBs to the theoretical framework of El Nio to explain these characteristics, and to improve our understanding and prediction of El Nio. | LIAN Tao CHEN DaKe TANG YouMin | 2017 | Science China Earth Sciences2017，60，9： | 9 |
| 8 | A 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 | 2022 | Chinese Journal of Aeronautics2022，35，1： | 9 |
| 9 | Progress 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 | 2018 | National Science Review2018，5，6： | 8 |
| 10 | Wavelet Neural Network Based on NARMA-L2 Model for Prediction of Thermal Characteristics in a Feed System显示文摘Research of thermal characteristics has been a key issue in the development of high-speed feed system. Most of the work carried out thus far is based on the principle of directly mapping the thermal error against the temperature of critical machine elements irrespective of the operating conditions. But recent researches show that different sets of operating parameters generated significantly different error values even though the temperature of the machine elements generated was similar. As such, it is important to develop a generic thermal error model which is capable of evaluating the positioning error induced by different operating parameters. This paper ultimately aims at the development of a comprehensive prediction model that can predict the thermal characteristics under different operating conditions (feeding speed, load and preload of ballscrew) in a feed system. A novel wavelet neural network based on feedback linearization autoregressive moving averaging (NARMA-L2) model is introduced to predict the temperature rise of sensitive points and thermal positioning errors considering the different operating conditions as the model inputs. Particle swarm optimization(PSO) algorithm is brought in as the training method. According to ISO230-2 Positioning Accuracy Measurement and ISO230-3 Thermal Effect Evaluation standards, experiments under different operating conditions were carried out on a self-made quasi high-speed feed system experimental bench HUST-FS-001 by using Pt100 as temperature sensor, and the positioning errors were measured by Heidenhain linear grating scale. The experiment results show that the recommended method can be used to predict temperature rise of sensitive points and thermal positioning errors with good accuracy. The work described in this paper lays a solid foundation of thermal error prediction and compensation in a feed system based on varying operating conditions and machine tool characteristics. | JIN Chao WU Bo HU Youmin | 2011 | Chinese Journal of Mechanical Engineering2011，24，1： | 8 |
| 11 | Transplant 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 | 2022 | Chinese Medical Journal2022，135，19： | 7 |
| 12 | A theoretical investigation of the tropical Indo-Pacific tripole mode显示文摘The El Ni o-Southern Oscillation(ENSO)phenomenon in the tropical Pacific has been a focus of ocean and climate studies in the last few decades.Recently,the short-term climate variability in the tropical Indian Ocean has attracted increasingly more attention,especially with the proposition of the Indian Ocean Dipole(IOD)mode.However,these phenomena are often studied separately without much consideration of their interaction.Observations reveal a striking out-of-phase relationship between zonal gradients of sea surface height anomaly(SSHA)and sea surface temperature anomaly(SSTA)in the tropical Indian and Pacific Oceans.Since the two oceans share the ascending branch of the Walker cells over the warm pool,the variation within one of them will affect the other.The accompanied zonal surface wind anomalies are always opposite over the two basins,thus producing a tripole structure with opposite zonal gradients of SSHA/SSTA in the two oceans.This mode of variability has been referred to as Indo-Pacific Tripole(IPT).Based on observational data analyses and a simple ocean-atmosphere coupled model,this study tries to identify the characteristics and physical mechanism of IPT with a particular emphasis on the relationships among ENSO,IOD,and IPT.The model includes the basic oceanic and atmospheric variables and the feedbacks between them,and takes into account the inter-basin connection through an atmospheric bridge,thus providing a valuable framework for further research on the short-term tropical climate variability. | LIAN Tao CHEN DaKe TANG YouMin JIN BaoGang | 2014 | Science China Earth Sciences2014，57，1： | 7 |
| 13 | Apparent 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 | 2011 | The Journal of Biomedical Research2011，25，3： | 7 |
| 14 | Effect 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 | 2023 | Journal of Magnesium and Alloys2023，11，1： | 6 |
| 15 | New 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 | 2021 | Science China(Information Sciences)2021，64，7： | 6 |
| 16 | A generalized Markov chain model based on generalized interval probability显示文摘In the traditional Markov chain model (MCM), aleatory uncertainty because of inherent randomness and epistemic uncertainty due to the lack of knowledge are not differentiated. Generalized interval probability provides a concise representation for the two kinds of uncertainties simultaneously. In this paper, a generalized Markov chain model (GMCM), based on the generalized interval probability theory, is proposed to improve the reliability of prediction. In the GMCM, aleatory uncertainty is represented as probability; interval is used to capture epistemic uncertainty. A case study for predicting the average dynamic compliance in machining processes is provided to demonstrate the effectiveness of proposed GMCM. The results show that the proposed GMCM has a better prediction performance than that of MCM. | XIE FengYun WU Bo HU YouMin WANG Yan | 2013 | Science China(Technological Sciences)2013，56，9： | 6 |
| 17 | Cooperative 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 | 2011 | Journal of Systems Engineering and Electronics2011，22，1： | 6 |
| 18 | Multi-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 | 2021 | Frontiers of Mechanical Engineering2021，16，2： | 6 |
| 19 | The diagnostic rules of peripheral lung cancer preliminary study based on data mining technique显示文摘Objective: To discuss the clinical and imaging diagnostic rules of peripheral lung cancer by data mining technique, and to explore new ideas in the diagnosis of peripheral lung cancer, and to obtain early-stage technology and knowledge support of computer-aided detecting(CAD). Methods: 58 cases of peripheral lung cancer confirmed by clinical pathology were collected. The data were imported into the database after the standardization of the clinical and CT findings attributes were identified. The data was studied comparatively based on Association Rules (AR) of the knowledge discovery process and the Rough Set (RS) reduction algorithm and Genetic Algorithm(GA) of the generic data analysis tool (ROSETTA), respectively. Results: The genetic classification algorithm of ROSETTA generates 5 000 or so diagnosis rules. The RS reduction algorithm of Johnson`s Algorithm generates 51 diagnosis rules and the AR algorithm generates 123 diagnosis rules. Three data mining methods basically consider gender, age, cough, location, lobulation sign, shape, ground-glass density attributes as the main basis for the diagnosis of peripheral lung cancer. Conclusion: These diagnosis rules for peripheral lung cancer with three data mining technology is same as clinical diagnostic rules, and these rules also can be used to build the knowledge base of expert system. This study demonstrated the potential values of data mining technology in clinical imaging diagnosis and differential diagnosis. | Yongqian Qiang Youmin Guo Xue Li Qiuping Wang Hao Chen Duwu Cui | 2007 | Journal of Nanjing Medical University2007，21，3： | 5 |
| 20 | On the “spring predictability barrier” for strong El Nio events as derived from an intermediate coupled model ensemble prediction system显示文摘Using predictions for the sea surface temperature anomaly(SSTA) generated by an intermediate coupled model(ICM)ensemble prediction system(EPS), we first explore the 'spring predictability barrier'(SPB) problem for the 2015/16 strong El Nio event from the perspective of error growth. By analyzing the growth tendency of the prediction errors for ensemble forecast members, we conclude that the prediction errors for the 2015/16 El Nio event tended to show a distinct season-dependent evolution, with prominent growth in spring and/or the beginning of the summer. This finding indicates that the predictions for the 2015/16 El Nio occurred a significant SPB phenomenon. We show that the SPB occurred in the 2015/16 El Nio predictions did not arise because of the uncertainties in the initial conditions but because of model errors. As such, the mean of ensemble forecast members filtered the effect of model errors and weakened the effect of the SPB, ultimately reducing the prediction errors for the 2015/16 El Nio event. By investigating the model errors represented by the tendency errors for the SSTA component,we demonstrate the prominent features of the tendency errors that often cause an SPB for the 2015/16 El Nio event and explain why the 2015/16 El Nio was under-predicted by the ICM EPS. Moreover, we reveal the typical feature of the tendency errors that cause not only a significant SPB but also an aggressively large prediction error. The feature is that the tendency errors present a zonal dipolar pattern with the west poles of positive anomalies in the equatorial western Pacific and the east poles of negative anomalies in the equatorial eastern Pacific. This tendency error bears great similarities with that of the most sensitive nonlinear forcing singular vector(NFSV)-tendency errors reported by Duan et al. and demonstrates the existence of an NFSV tendency error in realistic predictions. For other strong El Nio events, such as those that occurred in 1982/83 and 1997/98, we obtain the tendency errors of the NFSV structure, which cause a significant SPB and yield a much larger prediction error. These results suggest that the forecast skill of the ICM EPS for strong El Nio events could be greatly enhanced by using the NFSV-like tendency error to correct the model. | QI QianQian DUAN WanSuo ZHENG Fei TANG YouMin | 2017 | Science China Earth Sciences2017，60，9： | 5 |
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