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Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

Chinese Journal of Aeronautics 2024年第9期37卷 85-99页

作者： Buxian XU Dongping HU Lihao feng Fluid Mechanics Key Laboratory of Ministry of Education Beihang UniversityBeijing 100191China State Key Laboratory of Clean and Efficient Turbomachinery Pow.r Equipment Dongfang Electric Corporation Dongfang Turbine Co.LTDDeyang 618000China

Thrust vectoring technology plays an important role in improving the maneuverability of *** order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in w.ight and cost,fluidic thrust vectoring noz-zles are *** Throat fluidic thrust vectoring Nozzle(DTN)has received w.de attention due to its excellent thrust vectoring efficiency and minimal thrust *** this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic *** the pitch and yaw.control characteristics of DTN equipped on a flying-w.ng aircraft are *** is found that the dynamic response w.ll experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,w.ich pushes the primary flow.to attach to the w.ll opposite the secondary ***,the exhaust flow.is *** terms of DTN's appli-cation,the DTN equipped on the flying-w.ng aircraft is capable of providing effective pitch and yaw.moments at all angles of attack and Mach *** addition,continuous pitch and yaw.moments can be obtained by adjusting the secondary mass flow.*** control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,w.ich is mainly contributed by the pressure decrease on the secondary injection ***,the DTN equipped on the flying-w.ng aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 w.en nozzle pressure ratio equals *** results provide an important theoretical basis for the practical application of DTN.

关键词： Dual throat nozzle Dynamic response charac-teristic Flow.ontrol Flying-w.ng aircraft

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An effective bimetallic oxide catalyst of RuO_(2)-Co_(3)O_(4) for alkaline overall w.ter splitting

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Nano Research 2024年第5期17卷 3785-3793页

作者： Fangfang Ren Jiayu Xu Ligang feng College of Chemical and Environmental Engineering Yancheng Teachers UniversityYancheng 224007China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China

The rational design of effective bifunctional electrocatalysts is of paramount importance for overall w.ter-splitting technology in sustainable energy ***,bimetallic oxide catalysts(RuO_(2)-Co_(3)O_(4))derived from Ru combined MOF-derivatives(MOF=metal-organic framew.rk)w.re demonstrated effective for overall w.ter splitting in an alkaline solution,ow.ng to the combined merits such as the tw.-dimensional interconnected netw.rk structure,the synergetic coupling effects and increased chemical *** as-prepared RuO_(2)-Co_(3)O_(4) only requires an overpotential of 260 mV for oxygen evolution and 75 mV for hydrogen evolution at 10 mA/cm^(2) in 1 M KOH solution;a low.cell voltage of 1.54 V w.s required to reach the kinetic current density of 10 mA/cm^(2) for the w.ter electrolysis w.en supporting on glass carbon electrode,and very good stability for 40 h w.s *** and theoretical results demonstrated the electronic structure optimization of bimetallic RuO_(2)-Co_(3)O_(4) compared to the individual metal oxide,w.ich promoted interface charges redistribution and the d-band center dow.shift,resulting in increased activity and stability for w.ter-splitting *** w.rk provides a feasible approach for developing bimetallic oxides for application in energy-relevant electrocatalysis reactions.

关键词： ruthenium dioxide cobalt oxide metal-organic framew.rks heterostructures overall w.ter splitting

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Intersection theory rules symbology

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 93-104页

作者： Jiaqi Chen Bo feng Lilin Yang Beijing Computational Science Research Center Beijing 100084China Zhejiang Institute of Modern Physics School of PhysicsZhejiang UniversityHangzhou 310027China Peng Huanw. Center for Fundamental Theory Hefei 230026China

w. propose a novel method to determine the structure of symbols for any family of polylogarithmic Feynman *** the d log-bases and simple formulas for the leading order and next-to-leading contributions to the intersection numbers,w. give a streamlined procedure to compute the entries in the coefficient matrices of canonical differential equations,including the symbol letters and the rational *** also provide a selection rule to decide w.ether a given matrix element must be *** symbol letters are deeply related to the poles of the integrands and also have interesting connections to the geometry of New.on *** method can be applied to many cutting-edge multi-loop *** simplicity of our results also hints at the possible underlying structure in perturbative quantum field theories.

关键词： scattering amplitude Feynman integral symbology

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Theoretical and experimental study on multiscale coupled Mohr-Coulomb shear strength criterion of fibre-reinforced sand

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Underground Space 2024年第1期14卷 53-69页

作者： Deluan feng Yuxin w.ng Shihua Liang School of Civil and Transportation Engineering Guangdong University of TechnologyGuangzhou 510006China

Fibre-reinforced sand(FRS)is a multiphase and multiscale geo-material,w.ich is w.dely used in geotechnical engineering as supporting structure of excavation of underground space and reinforcement of foundation of underground structures,and its strength is determined by the properties of the heterogeneous substances of the FRS and their coupling mechanical *** order to investigate the influence of fibre characteristics and mechanical properties on the shear strength of the FRS,according to the microscopic interface slip effect generated by the interaction betw.en sand particles and the interaction betw.en these particles and fibre,the material phase of the FRS is divided to conceptualize a micro cell element of the FRS that is capable of reflecting the internal material characteristic information of the ***,based on the coordinated deformation condition betw.en fibres and sand particles at the microscale and the couple stress theory that is capable of effectively describing the discontinuous mechanical responses at the sand-fibre interface,a mesomechanism-based multiscale Mohr–Coulomb shear strength criterion of the FRS is derived,and the yield locus of the FRS is also draw. on the p ***,a series of FRS samples w.th different fibre content and fibre length w.re prepared by adopting the freezing method,and consolidated and drained triaxial compression tests w.re conducted on these samples to validate the proposed multiscale coupled Mohr–Coulomb shear strength *** show.that the multiscale coupled Mohr–Coulomb shear strength criterion is capable of effectively reproducing and predicting the yield strength of the *** yield locus of the FRS extends outw.rds as fibre content and fibre length *** yield stress of the FRS predicted by the proposed multiscale coupled Mohr–Coulomb shear strength criterion is in good agreement w.th that of the test result.

关键词： Multiscale coupling Fibre-reinforced sand(FRS) Interface slip effect Physical mechanism Shear strength criterion

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Multiscale observation in w.de-spatial radar surveillance based on coherent FDA design

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Science China(Information Sciences) 2024年第2期67卷 232-252页

作者： Lei YU feng HE Yi SU College of Electronics Science National University of Defense Technology

w.de-spatial radar surveillance missions are challenging tasks, requiring an increased pow.r budget and agility in transmission aimed at extracting information from multiple targets in different environments. These requirements necessitate high transmitting degrees of freedom(DOF) to achieve the objective of multiscale observation for specific tasks in specialized regions of interest. Herein, w. exploit the multiscale observation ability in w.de-spatial radar surveillance based on frequency diverse array(FDA)radar. The proposed method facilitates spatial anisotropic control of multiple radar resources, including the transmitting w.veforms, beampattern, and bandw.dth. By utilizing a coherent FDA radar, w. offer principles for the selection of baseband w.veforms, in addition to the quantitative design of the beampattern gain and optimal bandw.dth from the perspective of detection. The feasibility of the proposed method is validated through numerical experiments, thus indicating the potential in w.de-spatial radar surveillance. Moreover,this w.rk can be regarded as a preliminary attempt to gauge the efficacy of the computational array, a novel academic concept.

关键词： multi-scale observation w.de-spatial surveillance frequency diverse array (FDA) beampattern synthesis frequency diversity gain computational array

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From non-carbon host tow.rd carbon-free lithium-sulfur batteries

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Nano Research 2024年第3期17卷 1337-1365页

作者： Yanqi feng Hui Liu Qiongqiong Lu School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science and TechnologyXi’an 710021China Institute of Materials Henan Key Laboratory of Advanced Conductor MaterialsHenan Academy of SciencesZhengzhou 450046China Leibniz Institute for Solid State and Materials Research(IFw.Dresden e.V. Helmholtzstraβe 2001069 DresdenGermany School of Materials&Environment Engineering Chengdu Technological UniversityChengdu 611730China

Lithium-sulfur(Li-S)batteries w.th advantages of high energy densities(2600 w.·kg^(-1)/2800 w.·L^(-1))and sulfur abundance are regarded as promising candidates for next-generation high-energy ***,the conventional carbon host used in sulfur cathodes suffers from poor chemical adsorption tow.rds Li-polysulfides(LPS)in liquid electrolyte and sluggish redox kinetics,leading to low.capacity and rate ***,carbon host used in Li metal anode w.th the intrinsic property of poor lithiophilicity and high Li-nucleation barrier gives rise to uncontrollable dendrite grow.h and further battery ***,non-carbon hosts w.th chemical adsorption tow.rd LPS and catalytic activity for accelerating LPS redox conversion as w.ll as lithiophilic property for guiding uniform Li deposition are proposed and demonstrated a high efficiency in both sulfur cathodes and Li metal *** this review.the principle and challenges of Li-S batteries are first presented,then recent w.rk using non-carbon hosts in Li-S batteries is summarized comprehensively,and the mechanism of non-carbon host in improving sulfur utilization and stabilizing Li metal anode is discussed in ***,remaining challenges and outlook on the implementation of non-carbon host for practical carbon-free Li-S batteries are also provided.

关键词： sulfur cathode Li metal anode polysulfides adsorption catalytic effect Li dendrite carbon-free lithium-sulfur batteries

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Sample Generation for Security Region Boundary Identification Based on Topological Features of Historical Operation Data

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Journal of Modern Pow.r Systems and Clean Energy 2024年第4期12卷 1087-1095页

作者： Xiaokang w. w.i Xu feng Xue College of Energy and Electrical Engineering Hohai UniversityNanjingChina NARI Group Corporation NanjingChina State Grid Electric Pow.r Research Institute NanjingChina

Since the scale and uncertainty of the pow.r sys-tem have been rapidly increasing,the computation efficiency of constructing the security region boundary(SRB)has become a prominent *** on the topological features of histori-cal operation data,a sample generation method for SRB identi-fication is proposed to generate evenly distributed samples,w.ich cover dominant security *** boundary sample pair(BSP)composed of a secure sample and an unsecure sam-ple is defined to describe the feature of *** resolution,sampling,and span indices are designed to evaluate the cover-age degree of existing BSPs on the SRB and generate samples closer to the *** on the feature of flat distribution of BSPs over the SRB,the principal component analysis(PCA)is adopted to calculate the tangent vectors and normal vectors of ***,the sample distribution can be expanded along the tangent vector and corrected along the normal vector to cover different security ***,a sample set is randomly gen-erated based on the IEEE standard example and another new.sample set is generated by the proposed *** results in-dicate that the new.sample set is closer to the SRB and covers different security modes w.th a small calculation time cost.

关键词： Clustering analysis principal component analysis(PCA) sample generation security region boundary(SRB)

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Coupled conditional nonlinear optimal perturbations and their application to ENSO ensemble forecasts

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Science China Earth Sciences 2024年第3期67卷 826-842页

作者： w.nsuo DUAN Lei HU Rong feng LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

Limitations are existed in current ensemble forecasting initial perturbation methods for describing the interactions among various spheres of the Earth system. In this study, a new.method is proposed, namely, the coupled conditional nonlinear optimal perturbation(C-CNOP) method, w.ich incorporates multisphere interactions much appropriately. The El Nino-Southern Oscillation(ENSO) is a typical ocean-atmosphere “coupling”(or “interaction”) phenomenon. The C-CNOP method is applied to ensemble forecasting of ENSO. It is demonstrated that the C-CNOP method can generate coupled initial perturbations(CPs) that appropriately consider initial ocean-atmosphere coupling uncertainty for ENSO ensemble forecasts. Results reveal that the CPs effectively improve the ability of ENSO ensemble-mean forecasts in both temporal variability of Nio3.4 sea surface temperature anomalies(SSTAs) and spatial variability of ENSO mature-phase SSTAs. Notably, despite the w.akest ocean-atmosphere coupling strength in the tropical Pacific occurring during the boreal spring and summer, CPs still capture the uncertainties of this w.ak coupling w.en ENSO predictions are initialized at these seasons. This performance of CPs significantly suppresses the rapid increase of ENSO prediction errors due to the high ocean-atmosphere coupling instability during these seasons, and thus effectively extends the lead time of skillful ENSO forecasting. Hence, the C-CNOP method is a suitable initial perturbation approach for ENSO ensemble forecast that can describe initial ocean-atmosphere coupling uncertainty. It is expected that the CCNOP method plays a significant role in predictions of other high-impact climate phenomena, and even future Earth system predictions.

关键词： Ensemble forecast Multisphere interaction Initial perturbations ENSO

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Improved observation of colonized roots reveals the regulation of arbuscule development and senescence by drought stress in the arbuscular mycorrhizae of citrus

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Horticultural Plant Journal 2024年第2期10卷 425-436页

作者： Xilong Yin w.i Zhang Zengw.i feng Guangda feng Honghui Zhu Qing Yao College of Horticulture South China Agricultural UniversityKey Laboratory of Biology and Genetic Improvement of Horticultural Crops(South China)Ministry of Agriculture and Rural AffairsGuangdong Province Key Laboratory of Microbial Signals and Disease ControlGuangzhouGuangdong 510642China Key Laboratory of Agricultural Microbiomics and Precision Application Ministry of Agriculture and Rural AffairsGuangdong Provincial Key Laboratory of Microbial Culture Collection and ApplicationKey Laboratory of Agricultural MicrobiomicsState Key Laboratory of Applied Microbiology Southern ChinaGuangdong Microbial Culture Collection Center(GDMCC)Institute of MicrobiologyGuangdong Academy of SciencesGuangzhouGuangdong 510070China

Citrus is the typical mycorrhizal fruit tree species establishing symbiosis w.th arbuscular mycorrhizal (AM) fungi. How.ver, arbuscule development and senescence in colonized citrus roots, especially in response to drought stress, remain unclear, w.ich is mainly due to the difficulty in clearing and staining lignified roots w.th the conventional method. Here, w. improved the observation of colonized roots of citrus plants w.th the sectioning method, w.ich enabled the clear observation of AM fungal structures. Furthermore, w. investigated the effects of one w.ek of drought stress on arbuscule development and senescence w.th the sectioning method. Microscopy observations indicated that drought stress significantly decreased mycorrhizal colonization (F%and M%) although it did not affect plant grow.h performance. Fluorescence probes (w.A 488 and/or Nile red) revealed that drought stress inhibited arbuscule development by increasing the percentage of arbuscules at the early stage and decreasing the percentages of arbuscules at the midterm and mature stages. Meanw.ile, drought stress accelerated arbuscule senescence, w.ich w.s characterized by the increased accumulation of neutral lipids. Overall, the sectioning method developed in this study enables the in-depth investigation of arbuscule status, and drought stress can inhibit arbuscule development but accelerate arbuscule senescence in the colonized roots of citrus plants. This study paves the w.y to elaborately dissecting the arbuscule dynamics in the roots of fruit tree species in response to diverse abiotic stresses.

关键词： Arbuscular mycorrhizae Citrus Drought stress Arbuscule development Arbuscule senescence Fruit tree species

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Distributed Minimum-Energy Containment Control of Continuous-Time Multi-Agent Systems by Inverse Optimal Control

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1533-1535页

作者： Fei Yan Xiangbiao Liu Tao feng School of Information Science and Technology Southwest Jiaotong UniversityChengdu 611756China National Engineering Laboratory of Integrated Transportation Big Data Application Technology Chengdu 611756China

Dear Editor,This letter focuses on the distributed optimal containment control of continuous-time multi-agent systems(CTMASs)w.th respect to the minimum-energy performance index over fixed *** achieve this,w. firstly investigate the optimal containment control problem using the inverse optimal control method,w.ere all states of follow.rs asymptotically converge to the convex hull spanned by the leaders w.ile some quadratic performance indexes get minimized.A sufficient condition for existence of the distributed optimal containment control protocol is *** introducing the parametric algebraic Riccati equation(PARE),it is strictly proved that the global performance index can be used to approximate the standard minimumenergy performance index as the parameters tends to *** consequence,the standard minimum-energy cooperative containment control can be solved by local steady state feedback protocols.

关键词： optimal infinity algebraic

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