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Persistent Variations in the east Asian Trough from March to April and the Possible Mechanism

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Advances in Atmospheric Sciences 2024年第4期41卷 737-753,I0002-I0004页

作者： Shui yu Jianqi sun Nansen-Zhu International Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

The east Asian trough(eAT)profoundly influences the east Asian spring *** this study,the relationship of the eATs among the three spring months is *** analysis shows that the variation in March eAT is closely related to that of April *** empirical orthogonal function(eeOF)analysis also confirms the co-variation of the March and April *** positive/negative eeOF1 features the persistent strengthened/weakened eAT from March to *** investigation indicates that the variations in eeOF1 are related to a dipole sea surface temperature(SST)pattern over the North Atlantic and the SST anomaly over the tropical Indian *** dipole SST pattern over the North Atlantic,with one center east of Newfoundland Island and another east of Bermuda,could trigger a Rossby wave train to influence the eAT in March−*** SST anomaly over the tropical Indian Ocean can change the Walker circulation and influence the atmospheric circulation over the tropical western Pacific,subsequently impacting the southern part of the eAT in March−*** the SST factors,the Northeast Asian snow cover could change the regional thermal conditions and lead to persistent eAT anomalies from March to *** three impact factors are generally independent of each other,jointly explaining large variations in the eAT ***,the signals of the three factors could be traced back to February,consequently providing a potential prediction source for the eAT variation in March and April.

关键词： spring east Asian trough sea surface temperature snow cover

Cooperative game penetration guidance for multiple hypersonic vehicles under safety critical framework

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Chinese Journal of Aeronautics 2024年第1期37卷 247-255页

作者： Jieqing CHeN Ruisheng sun yu LU School of energy and Power engineering Nanjing University of Science and TechnologyNanjing 210094China

The rapid development of the anti-missile weapon technology brings new challenges to the cooperative penetration strategy solution and the guidance law design for Hypersonic Vehicles(HVs).This paper studies the coordinated game penetration guidance problem for multiple hypersonic vehicles faced with space threat areas.A scheme for seeking cooperative game penetration guidance strategy under safety critical control framework is *** this scheme,a multiHV cooperative game model is proposed in a minimum optimization form which can simplify the solving process and accelerate the computing ***,a second-order control barrier function is developed to transform the implicit nonlinear constraints of the proposed model into linear *** order to obtain better performance of guidance strategy,a composite guidance law under the safety critical control framework is presented to allocate guidance strategies appropriately in the whole *** is shown that the proposed scheme can guarantee successful penetration while avoiding threat ***,a comparative simulation with a two-on-three game is conducted to verify the effectiveness of the proposed method.

关键词： Hypersonic vehicles Safety critical control Penetration game Space constraints Cooperative guidance

Direct numerical simulation of shock wave/boundary layer interaction controlled by steady microjet in a compression ramp

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Chinese Journal of Aeronautics 2024年第10期37卷 83-102页

作者： Ruoye XIAO Dong sun Jian yu School of Aeronautic Science and engineering Beihang UniversityBeijing 100191China State Key Laboratory of Aerodynamics Mianyang 621000China

Shock wave/boundary layer interaction in a 24°turning angle of the compression ramp at Mach number 2.9 controlled by steady microjet is investigated using direct numerical *** different jet spacings which are termed as sparse,moderate and dense are considered,and the induced vortex system and shock structures are compared.A moderate jet spacing configuration is found to generate counter-rotating vortex pairs that transport high-momentum fluid towards the vicinity of wall and strengthen the boundary layer to resist separation,reducing the separation *** dense jet spacing configuration creates a larger momentum deficit region,reducing the friction downstream of the *** of pressure and pressure gradient reveals that dense jet spacing configuration reduces the intensity of separation *** impact of varying jet spacings on the turbulent kinetic energy transport mechanism is also investigated by decomposing the budget terms in the transport ***,the spectral characteristics of the separation region are studied using power spectral density and dynamic mode decomposition methods,revealing that moderate jet spacing configuration suppresses low-frequency fluctuations in the separation region.

关键词： Shock wave/boundary layer interaction Compression ramp Steady microjet Different jet spacings Direct numerical simulation

A Note on Gradient estimates for elliptic equations with Discontinuous Coefficients

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 1-10页

作者： yu PeNG Xiandong sun Huichun ZHANG Department of Mathematics Sun Yat-Sen UniversityGuangzhou 510275China.

The authors will use a method in metric geometry to show an L^(P)-estimate for gradient of the weak solutions to elliptic equations with discontinuous coefficients,even the BMO semi-norms of the coefficients are not *... 详细信息

关键词： L^(p)-estimate elliptic equation Discontinuous coefficients

Application of system identification in a practical active noise control system

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Control Theory and Technology 2024年第2期22卷 282-291页

作者： yu yuan Zhaoyang sun Hongwei Zhang School of Mechanical engineering Xihua UniversityChengdu610039SichuanChina School of electrical engineering Southwest Jiaotong UniversityChengdu611756SichuanChina School of Mechanical engineering and Automation Harbin Institute of TechnologyShenzhen518055GuangdongChina

Noise pollution has become increasingly severe around the world due to fast urbanization. How to soundproof windows from outside noise is of significant interest for both academia and industry. This paper reports an experimental implementation of normalized minmax active noise control (ANC) algorithm on an open window system, where identifying the model of acoustic sound paths plays a central role. By doing this, traffic noise is attenuated by the ANC system, leading to a relatively quiet indoor environment, while the natural lighting and ventilation functions of a window are remained. Our experiments show that an average of 19 dB(A) noise reduction is achieved.

关键词： Active noise control Multi-input-multi-output system Normalized minimax algorithm System identification

An improved high-fidelity adaptive model for integrated inlet-engine-nozzle based on mechanismdata fusion

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Chinese Journal of Aeronautics 2024年第8期37卷 190-207页

作者： Chen WANG Ziyang yu Xian DU Ximing sun School of Control Science and engineering Dalian University of TechnologyDalian 116024China Key Laboratory of Intelligent Control and Optimization for Industrial equipment Ministry of EducationDalian University of TechnologyDalian 116024China

Nowadays,there has been an increasing focus on integrated flight propulsion control and the inlet-exhaust design for the aero-propulsion *** component-level models are inadequate due to installed performance deviations and mismatches between the real engine and the model,failing to meet the accuracy requirements of supersonic *** paper establishes a quasi-one-dimensional model for the inlet-exhaust system and conducts experimental ***,a mechanism-data fusion adaptive modeling scheme using an extreme Learning Machine based on the Salp Swarm Algorithm(SSA-eLM)is *** study reveals the inlet model’s efficacy in reflecting installed performance,flow matching,and mitigating pressure distortion,while the nozzle model accurately predicts flow coefficients and thrust coefficients,and identifies various operational *** model’s output closely aligns with typical experimental *** combining offline optimization and online adaptive correction,the mechanismdata fusion adaptive model substantially reduces output errors during regular flights and varying levels of degradation,and effectively handles gradual degradation within a single flight ***,the mechanism-data fusion adaptive model holistically addresses total pressure errors within the inlet-exhaust system and normal shock location *** approach significantly curbs performance deviations in supersonic *** example,at Ma=2.0,the system error impressively drops from 34.17%to merely 6.54%,while errors for other flight conditions consistently stay below the 2.95%*** findings underscore the clear superiority of the proposed method.

关键词： Aero-propulsion system Integrated inlet-enginenozzle Component-level model On-board adaptive model Mechanism-data fusion extreme learning machine

Interface failure of segmental tunnel lining strengthened with steel plates based on fracture mechanics

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Frontiers of Structural and Civil engineering 2024年第1期18卷 137-149页

作者： Yazhen sun Yang yu Jinchang WANG Longyan WANG School of Transportation and Geomatics engineering Shenyang Jianzhu UniversityShenyang 110168China School of Civil engineering Shenyang Jianzhu UniversityShenyang 110168China Institute of Transportation engineering Zhejiang UniversityHangzhou 310058China Center for Balance Architecture Zhejiang UniversityHangzhou310058China

Segmental tunnel lining strengthened with steel plates is widely used worldwide to provide a permanent strengthening *** existing studies assume an ideal steel-concrete interface,ignoring discontinuous deformation characteristics,making it difficult to accurately analyze the strengthened structure’s failure *** this study,interfacial fracture mechanics of composite material was applied to the segmental tunnel lining strengthened with steel plates,and a numerical three-dimensional solid nonlinear model of the lining structure was established,combining the extended finite element method with a cohesive-zone model to account for the discontinuous deformation characteristics of the *** results accurately describe the crack propagation process,and are verified by full-scale ***,dynamic simulations based on the calibrated model were conducted to analyze the sliding failure and cracking of the steel-concrete ***,detailed location of the interface bonding failure are further verified by model *** results show that,the cracking failure and bond failure of the interface are the decisive factors determining the instability and failure of the strengthened *** proposed numerical analysis is a major step forward in revealing the interface failure mechanism of strengthened composite material structures.

关键词： segmental tunnel lining steel plate strengthening connecting interface cohesive-zone model extended finite element method

event-Triggered Bipartite Consensus Tracking and Vibration Control of Flexible Timoshenko Manipulators Under Time-Varying Actuator Faults

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Ieee/CAA Journal of Automatica Sinica 2024年第5期11卷 1190-1201页

作者： Xiangqian Yao Hao sun Zhijia Zhao yu Liu School of Automation Science and engineering South China University of TechnologyGuangzhou 510640China Yongjiang Laboratory Ningbo 315202 School of Astronautics Harbin Institute of TechnologyHarbin 150001China School of Mechanical and electrical engineering Guangzhou UniversityGuangzhou 510006China

For bipartite angle consensus tracking and vibration suppression of multiple Timoshenko manipulator systems with time-varying actuator faults,parameter and modeling uncertainties,and unknown disturbances,a novel distributed boundary event-triggered control strategy is proposed in this *** contrast to the earlier findings,time-varying consensus tracking and actuator defects are taken into account *** addition,the constructed event-triggered control mechanism can achieve a more flexible design because it is not required to satisfy the input-to-state *** achieve the control objectives,some new integral control variables are given by using back-stepping technique and boundary ***,adaptive neural networks are applied to estimate system *** the proposed event-triggered scheme,control inputs can reduce unnecessary ***,tracking errors and vibration states of the closed-looped network can be exponentially convergent into some small fields,and Zeno behaviors can be *** last,some simulation examples are given to state the effectiveness of the control algorithms.

关键词： Vibration satisfy bipartite

effect of nourishing Yin and purging fire Chinese herbal mixture on delaying light-induced premature puberty in rats

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Journal of Traditional Chinese Medicine 2024年第1期44卷 95-102页

作者： sun Yanyan XUe yuanyuan sun Wen WANG Yonghong yu Jian Department of Traditional Chinese Medicine Children's Hospital of Fudan UniversityShanghai 201102China Department of Pediatrics Zibo Central HospitalZibo 255000China

OBJeCTIVe:To elucidate the mechanism of the nourishing Yin and purging fire Chinese herbal mixture(NYPF)in delaying light-induced premature puberty in ***:Twenty-one days old female SpragueDawley rats were randomly assigned to normal group(N),long light exposure group(L),NYPF and normal saline group(NS).Rats in the L,NYPF and NS groups were exposed to 16 h:350 lux light/8 h:dark,while rats in the N group were exposed to 12 h:50 lux light/12 h:*** and normal saline was administered to the rats in the NYPF group or NS group,respectively,from day *** rats in every group were sacrificed at 9 *** day 28(P28),on the day when rat's vulva opened in the L group(L-VO),on the day when the first estrous interphase occurred in rats of L group(L-e1),and on the day when the second estrous interphase occurred in rats of L group(L-e2),***:On day 34,all rats in the L group,80%of rats in the NS group,40%of rats in the N group,and 20%of rats in the NYPF group showed complete opening of the *** P28,m RNA level of hypothalamic kisspeptin(Kiss-1)in the L group was significantly higher than that in the N group(Pe rats in the L and NS groups had significantly lower hypothalamic argininephenylalanine-amide(RFamide)-related peptide 3(RFRP-3)m RNA levels than those in the N group(Pereas RFRP-3 m RNA level was significantly higher in the NYPF group than that in the L group(Pe ovarian index of the L and NS groups was significantly higher than that of the N group(Pestradiol(e2)level of the NYPF group was significantly lower than that of the N and NS groups(Pevel in the L and NS groups was significantly higher than that in the N and NYPF groups(Pereas hypothalamic RFRP-3 m RNA level in the L,NYPF,and NS groups was significantly lower than that in the N group(Pe1,e2 level of the L and NS groups was significantly higher than that of the N group(Per

关键词： light puberty precocious kisspeptins RFRP-3 melatonin Nourishing Yin and Purging Fire