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Accurately tracking hypersonic gliding vehicles via an LEO mega-constellation in relay tracking mode

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Journal of Systems Engineering and Electronics 2024年第1期35卷 211-221页

作者： LI Zhao WANG Yidi zheng wei College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

In order to effectively defend against the threats of the hypersonic gliding vehicles(HGVs),HGVs should be tracked as early as possible,which is beyond the capability of the ground-based *** benefited by the developing megaconstellations in low-Earth orbit,this paper proposes a relay tracking mode to track HGVs to overcome the above *** whole tracking mission is composed of several tracking intervals with the same *** each tracking interval,several appropriate satellites are dispatched to track the *** that are planned to take part in the tracking mission are selected by a new derived observability *** tracking performances of the proposed tracking mode and the other two traditional tracking modes,including the stare and track-rate modes,are compared by *** results show that the relay tracking mode can track the whole trajectory of a HGV,while the stare mode can only provide a very short tracking ***,the relay tracking mode achieve higher tracking accuracy with fewer attitude controls than the track-rate mode.

关键词： target tracking mega-constellation hypersonic gliding vehicle(HGV) sensor selection observability analysis

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Improving the spaceborne GNSS-R altimetric precision based on the novel multilayer feedforward neural network weighted joint prediction model

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Defence Technology（防务技术） 2024年第2期32卷 271-284页

作者： Yiwen Zhang wei zheng Zongqiang Liu Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China China Academy of Aerospace Science and Innovation Beijing 100176China State Key Laboratory of Space-Ground Integrated Information Technology Beijing Institute of Satellite Information EngineeringBeijing 100194China

Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at the global scale required for underwater *** present,there are still research gaps for GNSS-R altimetry under this mode,and its altimetric capability cannot be specifically ***,GNSS-R satellite constellations that meet the global altimetry needs to be ***,the matching precision prediction model needs to be established to quantitatively predict the GNSS-R constellation altimetric ***,the GNSS-R constellations altimetric precision under different configuration parameters is calculated,and the mechanism of the influence of orbital altitude,orbital inclination,number of satellites and simulation period on the precision is analyzed,and a new multilayer feedforward neural network weighted joint prediction model is ***,the fit of the prediction model is verified and the performance capability of the model is tested by calculating the R2 value of the model as 0.9972 and the root mean square error(RMSE)as 0.0022,which indicates that the prediction capability of the model is ***,using the novel multilayer feedforward neural network weighted joint prediction model,and considering the research results and realistic costs,it is proposed that when the constellation is set to an orbital altitude of 500 km,orbital inclination of 75and the number of satellites is 6,the altimetry precision can reach 0.0732 m within one year simulation period,which can meet the requirements of underwater navigation precision,and thus can provide a reference basis for subsequent research on spaceborne GNSS-R sea surface altimetry.

关键词： GNSS-R satellite constellations Sea surface altimetric precision Underwater navigation Multilayer feedforward neural network

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High-Order Decoupled and Bound Preserving Local Discontinuous Galerkin Methods for a Class of Chemotaxis Models

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Communications on Applied Mathematics and Computation 2024年第1期6卷 372-398页

作者： wei zheng Yan Xu School of Mathematical Sciences University of Science and Technology of ChinaHefei230026AnhuiChina

In this paper,we explore bound preserving and high-order accurate local discontinuous Galerkin(LDG)schemes to solve a class of chemotaxis models,including the classical Keller-Segel(KS)model and two other density-dependent *** use the convex splitting method,the variant energy quadratization method,and the scalar auxiliary variable method coupled with the LDG method to construct first-order temporal accurate schemes based on the gradient flow structure of the *** semi-implicit schemes are decoupled,energy stable,and can be extended to high accuracy schemes using the semi-implicit spectral deferred correction *** bound preserving DG discretizations are only worked on explicit time integration methods and are difficult to get high-order *** overcome these difficulties,we use the Lagrange multipliers to enforce the implicit or semi-implicit LDG schemes to satisfy the bound constraints at each time *** bound preserving limiter results in the Karush-Kuhn-Tucker condition,which can be solved by an efficient active set semi-smooth Newton *** numerical experiments illustrate the high-order accuracy and the effect of bound preserving.

关键词： Chemotaxis models Local discontinuous Galerkin(LDG)scheme Convex splitting method Variant energy quadratization method Scalar auxiliary variable method Spectral deferred correction method

Exploring the Effect of Plasticity on the Phase Imaging of TM-AFM Through Molecular Dynamics Simulations

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Acta Mechanica Solida Sinica 2024年第2期37卷 297-304页

作者： Guolin Liu Yu Zeng Yaxin Chen zheng wei School of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing100029China

In the tapping-mode atomic force microscope(TM-AFM),the probe tip continuously taps the sample surface,which may cause plastic deformation of the sample and result in energy *** energy dissipation of the probe is closely related to the scanned phase *** quantify the energy dissipation due to plastic indentations of the sample,this study utilized a combination of molecular dynamics(MD)simulations and experiments on single-crystal copper samples,including multiple nano-indentation *** energy dissipation of the probe due to the plastic deformation of the sample was calculated by integrating the hysteresis curve of the indentation depth versus the force applied to the *** simulation results are in good agreement with the experimental *** sets of results have demonstrated that the plastic energy dissipation decreases as the number of indentations increases,and eventually the energy of the probe tends to *** equilibrium energy dissipation is associated with other dissipation ***,it was observed that,after hundreds of taps,the dissipated energy of plastic deformation could be ignored,implying that the scanned image may not reflect the plasticity information of the sample after multiple taps of the probe on the sample surface for scanning.

关键词： Atomic force microscopy Force-distance curves Nano-indentations Plasticity Molecular dynamics

Superconducting,Topological,and Transport Properties of Kagome Metals CsTi_(3)Bi_(5)and RbTi_(3)Bi_(5)

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Research 2024年第2期2023卷 753-762页

作者： Xin-wei Yi zheng-wei Liao Jing-Yang You Bo Gu Gang Su School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Physics Faculty of ScienceNational University of Singapore117551Singapore Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum ComputationUniversity of Chinese Academy of SciencesBeijing 100190China

The recently discovered ATi_(3)Bi_(5)(A=Cs,Rb)exhibit intriguing quantum phenomena including superconductivity,electronic nematicity,and abundant topological ***_(3)Bi_(5)present promising platforms for studying kagome superconductivity,band topology,and charge orders in parallel with *** this work,we comprehensively analyze various properties of ATi_(3)Bi_(5)covering superconductivity under pressure and doping,band topology under pressure,thermal conductivity,heat capacity,electrical resistance,and spin Hall conductivity(SHC)using first-principles *** superconducting transition temperature(Tc)of CsTi_(3)Bi_(5)and RbTi_(3)Bi_(5)at ambient pressure are about 1.85 and 1.92 *** subject to pressure,Tc of CsTi_(3)Bi_(5)exhibits a special valley and dome shape,which arises from quasi-two-dimensional compression to three-dimensional isotropic compression within the context of an overall decreasing ***,Tc of RbTi_(3)Bi_(5)can be effectively enhanced up to 3.09 K by tuning the kagome van Hove singularities(VHSs)and flat band through *** can also induce abundant topological surface states at the Fermi energy(EF)and tune VHSs across ***,our transport calculations are in excellent agreement with recent experiments,confirming the absence of charge density ***,SHC of CsTi_(3)Bi_(5)can reach up to 226h·(e·Ω·cm)^(-1)at *** work provides a timely and detailed analysis of the rich physical properties for ATi_(3)Bi_(5),offering valuable insights for further experimental verifications and investigations in this field.

关键词： doping superconductivity conductivity

Improving path planning efficiency for underwater gravity-aided navigation based on a new depth sorting fast search algorithm

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Defence Technology（防务技术） 2024年第2期32卷 285-296页

作者： Xiaocong Zhou wei zheng Zhaowei Li Panlong Wu Yongjin Sun School of Automation Nanjing University of Science and TechnologyNanjing210094China China Academy of Aerospace Science and Innovation Beijing100176China Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing100094China School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin150001China

This study focuses on the improvement of path planning efficiency for underwater gravity-aided ***,a Depth Sorting Fast Search(DSFS)algorithm was proposed to improve the planning speed of the Quick Rapidly-exploring Random Trees*(Q-RRT*)algorithm.A cost inequality relationship between an ancestor and its descendants was derived,and the ancestors were filtered ***,the underwater gravity-aided navigation path planning system was designed based on the DSFS algorithm,taking into account the fitness,safety,and asymptotic optimality of the routes,according to the gravity suitability distribution of the navigation ***,experimental comparisons of the computing performance of the ChooseParent procedure,the Rewire procedure,and the combination of the two procedures for Q-RRT*and DSFS were conducted under the same planning environment and parameter conditions,*** results showed that the computational efficiency of the DSFS algorithm was improved by about 1.2 times compared with the Q-RRT*algorithm while ensuring correct computational results.

关键词： Depth Sorting Fast Search algorithm Underwater gravity-aided navigation Path planning efficiency Quick Rapidly-exploring Random Trees*(QRRT*)

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Role of Vickers Ligament in the Pathogenesis of Madelung Deformity

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当代医学科学（英文） 2024年第4期44卷 735-740页

作者： Ge XIONG wei zheng Li-hua GONG Department of Hand Surgery Beijing Jishuitan HospitalCapital Medical UniversityBeijing 100035China Department of Pathology Beijing Jishuitan HospitalCapital Medical UniversityBeijing 100035China

Objective:The Vickers ligament is thought to hinder the growth of palmar ulnar radius by tethering the lunate to the radius,leading to Madelung *** purpose of this study was to clarify the nature of the Vickers ligament and investigate its pathogenesis in Madelung deformities based on our observation of the Vickers ***:All 22 patients(33 wrists)with Madelung deformities treated surgically between 2018 and 2022 were *** diagnosis was confirmed radiographically in all *** three-dimensional computed tomography(3D-CT)data of 16 patients(19 wrists)were *** resonance imaging(MRI)data were available for 9 patients(14 wrists).Wrist arthroscopy was used in 4 *** Vickers ligament was resected and submitted for histopathological examination in 8 *** outcomes,3D-CT,MRI,arthroscopy,surgical findings,and histopathology of the Vickers ligament were ***:The 3D-CT revealed that the Vickers ligament originated in the metaphysis and formed a metaphyseal defect at the palmar ulnar *** the sequential MR coronal images,the Vickers ligament could be divided into 3 branches,extending to the lunate,triquetrum and ulnar *** and surgical findings revealed that the nature of the Vickers ligament was the stretched palmar ligament of the *** histopathology results revealed ligamentous tissue and fibrocartilaginous metaplasia with a structure similar to that of the triangular fibrocartilage complex(TFCC).Conclusions:The Vickers ligament is not a separate aberrant *** nature of the Vickers ligament is a combination of the stretched TFCC ligament(palmar radioulnar ligament,ulnotriquetral ligament and ulnolunate ligament)and radiolunate *** possible pathogenesis of Madelung deformity might be focal early epiphyseal closure at the middle part of the sigmoid notch,which leads to focal growth retardation of the radius and pulls palmar ligaments proximally to for

关键词： Madelung deformity Vickers ligament computed tomography magnetic resonance imaging pathogenesis

Superplastic Tension Behavior of Dissimilar TC4/SP700 Laminate through Diffusion Bonding

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 353-363页

作者： Qianwen Zhang Tianle Li Yanbin Han wei zheng Xifeng Li Jianjun Wu School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an710072China AVIC Xi’an Aircraft Industry Group Company Ltd Xi’an710089China Institute of Forming Technology and Equipment School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai200030China

Superplastic forming is a practical method to manufacture complex-shaped parts of titanium alloys with large *** parts of dissimilar titanium alloys fabricated by superplastic forming can achieve excellent performance by combining the advantages of *** work displays the superplastic tension behavior and microstructural evolution of dissimilar TC4/SP700 laminate prepared by the diffusion bonding *** titanium alloys can achieve metallurgical bonding at parameters of 800℃/1 h/5 *** for dynamic recrystallization and grain growth behaviors upon superplastic tension,stress-induced phase transformation plays an important role inαtoβphase transformation apart from the elevated *** superplastic deformation can be attributed to the grain boundary sliding accommodated multiplex motion of *** addition,the retained strengths of all dissimilar TC4/SP700 laminates after superplastic deformation with different strain rates and temperatures range from 807 to 890 MPa.

关键词： TC4/SP700 laminate Diffusion bonding Microstructure Superplastic tension Strength

Fluorescent carbon dots synthesized in solid phase and air for application in LEDs

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Nano Research 2024年第9期17卷 8495-8503页

作者： wei-Jie zheng Zhao-Nan Sun Yi-Ming Wang Huan-Ming Xiong Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan UniversityShanghai 200438China

Carbon dots(CDs)have been widely adopted as optical materials because of their excellent luminescent ***,most of the reported synthetic methods are conducted in solvents,especially hydrothermal/solvothermal reactions,leading to intractable problems such as toxic and flammable solvents,complex and inseparable by-products,and dangerously high pressures and ***-phase synthesis of CDs in air is an effective solution to overcome the above issues,but solid reactions always result in uncontrolled growth and agglomeration of *** this study,some inorganic salts are selected as catalysts for synthesizing CDs in solid states and air,which also play as dispersants to hinder CDs *** the meantime,some aromatic derivatives containing hydroxyl and amino groups are chosen as carbon sources,ground with the optimized catalyst,and then heated together in *** production yields are affected by the reaction time and reactant ratio,while the graphitization degrees of the CDs are determined by the reaction *** IG/ID value of their Raman spectra increases from 0.59 to 0.85,and the particle size decreases from 2.5 to 1.4 nm when the synthesis temperature is increased from 200 to 280℃.The as-prepared CDs show emission peaks ranging from 366 to 606 nm,with the photoluminescence(PL)quantum yield up to 53%.Their emission color variation mainly results from different carbon sources,which can be ascribed to the differences in the element composition,functional groups,and graphitic nitrogen content of these *** dispersing CDs of different concentrations into polyvinyl alcohol(PVA)and combining them with blue LEDs,cold,standard,and warm white light emitting devices(WLEDs)are prepared,with a color rendering index(CRI)up to *** the as-prepared CDs have antioxidant ability at high temperature,the as-prepared WLEDs have long lifespans,remaining the effective white luminescence after 72 h continuous work.

关键词： carbon dot solid-phase synthesis white LED photoluminescence inorganic salt catalysis