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Deep carbon recycling viewed from global plate tectonics

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National Science Review 2024年第06期11卷 37-55页

作者： Maoliang Zhang Sheng xu Yuji Sano School of Earth System Science Tianjin University Marine Core Research Institute Kochi University Atmosphere and Ocean Research Institute The University of Tokyo

Plate tectonics plays an essential role in the redistribution of life-essential volatile elements between Earth's interior and surface, whereby our planet has been well tuned to maintain enduring habitability over much of its history. Here we present an overview of deep carbon recycling in the regime of modern plate tectonics,with a special focus on convergent plate margins for assessing global carbon mass balance. The up-to-date flux compilation implies an approximate balance between deep carbon outflux and subduction carbon influx within uncertainty but remarkably limited return of carbon to convecting mantle. If correct, carbon would gradually accumulate in the lithosphere over time by（i） massive subsurface carbon storage occurring primarily in continental lithosphere from convergent margins to continental interior and（ii） persistent surface carbon sinks to seafloors sustained by high-flux deep CO2emissions to the atmosphere. Further assessment of global carbon mass balance requires updates on fluxes of subduction-driven carbon recycling paths and reduction in uncertainty of deep carbon outflux. From a global plate tectonics point of view, we particularly emphasize that continental reworking is an important mechanism for remobilizing geologically sequestered carbon in continental crust and sub-continental lithospheric mantle. In light of recent advances,future research is suggested to focus on a better understanding of the reservoirs, fluxes, mechanisms, and climatic effects of deep carbon recycling following an integrated methodology of observation, experiment,and numerical modeling, with the aim of decoding the self-regulating Earth system and its habitability from the deep carbon recycling perspective.

关键词： deep carbon recycling convergent plate margins subduction continental reworking global carbon mass balance

Vascularization ability of glioma stem cells in different three-dimensional microenvironments

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Regenerative Biomaterials 2024年第1期3卷 34-43页

作者： xuanzhi Wang Tao xu Chaoshi Niu Department of Neurosurgery The First Affliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiAnhui230036China Department of Neurosurgery Sichuan Provincial People's HospitalUniversity of Electronic Science and Technology of ChinaChengdu 610072People's Republic of China Center for Bio-intelligent Manufacturing and Living Matter Bioprinting Research Institute of Tsinghua University in ShenzhenTsinghua UniversityShenzhen 518057People's Republicof China

Glioblastoma(GBM)is among the most common and aggressive adult central nervous system *** prominent charac-teristic of GBM is the presence of abnormal microvessels.A significant correlation between angiogenesis and prognosis has been *** reconstructing this neovascula-rization and tumor microenvironment through personalized in vitro disease models presents a significant ***,it is crucial to develop new anti-angiogenic therapies for *** this study,3D bioprinted glioma stem cell(GSC)-laden hydrogel scaffolds,hybrid Gsc hydrogels and ceil-free hydrogel scaffolds were manufactured to investigate the vas-cularization ability of GsCs in varying 3D microenvironments.

关键词： 3D bioprinting xenograft tumors GSC-laden hydrogel scaffold glioblastoma angiogenesis

Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

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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 Power 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 weight and cost,fluidic thrust vectoring noz-zles are *** Throat fluidic thrust vectoring Nozzle(DTN)has received wide 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-wing aircraft are *** is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary ***,the exhaust flow is *** terms of DTN's appli-cation,the DTN equipped on the flying-wing 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,which is mainly contributed by the pressure decrease on the secondary injection ***,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 when 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 Flowcontrol Flying-wing aircraft

Assessment of tree-ring mercury radial translocation and age effect in Masson pine:Implications for historical atmospheric mercury reconstruction

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Journal of Environmental Sciences 2024年第4期138卷 266-276页

作者： xu Liu xun Wang Dingyong Wang College of Resources and Environment Southwest UniversityChongqing 400715China State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

The tree ring has been regarded as an emerging archive to reconstruct historical atmospheric mercury(Hg)trends,but with the large knowledge gaps in the *** this study,we comprehensively evaluated the Hg source,radial translocation and age effect of Masson pine(Pinus massoniana)tree ring at *** in Chongqing,to assess the suitability of such tree ring as the archive of atmospheric *** showed that distinct variabilities among Masson pine tree-ring Hg concentration *** Hg concentration significantly increased along with stem height(P<0.05),indicating the Hg in tree rings mainly derived from foliage uptake atmospheric *** found a distinct age effect that the tree ring of young trees had the higher Hg ***,we used the advection-diffusion model to demonstrate how Hg concentration shifted by the advection or/and diffusion in tree *** modeling results showed that the advection induced radial translocation during the young growth period of tree was a plausible mechanism to result in the tree-ring Hg record largely different from the trend of anthropogenic Hg emissions in *** finally suggest that in further Hg dendrochemistry,better discarding the tree-ring Hg profile of the young growth period to reduce impacts of the radial translocation and age effect.

关键词： Masson pine Tree-ring mercury Radial translocation Tree age effect

Cooperative guidance law with maneuverability awareness:A decentralized solution

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Chinese Journal of Aeronautics 2024年第7期37卷 450-457页

作者： Shuyang xu xun SONG Chaoyong LI College of Electrical Engineering Zhejiang UniversityHangzhou 310027China Beijing Institute of Electronic System Engineering Beijing 100074China

In this paper,we propose a cooperative guidance law aimed to achieve coordinated impact angles with limited observation on target *** primary challenge lies in establishing an appropriate communication graph among all missiles and devising an algorithm to estimate target acceleration information during *** address this,we propose a specific communication topology and employ a numerical integration-based estimation ***,a distributed algorithm is introduced to facilitate consensus on target acceleration *** upon these foundations,we design an optimal-control-based distributed guidance law for each *** of the proposed guidance law is validated through numerical simulations.

关键词： Cooperative guidance Target maneuver estimation Distributed estimation Consensus Optimal control

Design and Verification of Parallel Hip Exoskeleton Considering Output Torque Anisotropy

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Journal of Bionic Engineering 2024年第3期21卷 1305-1320页

作者： Jilong xu Yunzhan Niu Fucai Liu Engineering Research Center of the Ministry of Education for Intelligent Control System and Intelligent Equipment Yanshan UniversityQinhuangdao066004China Key Laboratory of Industrial Computer Control Engineering of Heibei Province Yanshan UniversityQinhuangdao066004China College of Mechanical Engineering Yanshan UniversityQinhuangdao066004China

In rehabilitation training,it is crucial to consider the compatibility between exoskeletons and human legs in ***,most exoskeletons today adopt an anthropomorphic serial structure,which results in rotational centers that are not precisely aligned with the center of the hip *** address this issue,we introduce a novel exoskeleton called the Parallel Hip Exoskeleton(PH-Exo)in this ***-Exo is meticulously designed based on the anisotropic law of output *** the friction of the drive components,a dynamic model of the human-machine complex is *** analysis demonstrates that PH-Exo not only exhibits outstanding torque performance but also achieves high controllability in both flexion/extension and adduction/abduction ***,a robust controller is designed to address model uncertainty,friction,and external *** experiments indicate that under the control of the robust controller,each motor achieves excellent tracking performance.

关键词： Hip exoskeleton Parallel mechanism Misalignment Anisotropy Output torque

Discovery of Partial Differential Equations from Highly Noisy and Sparse Data with Physics-Informed Information Criterion

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Research 2024年第1期2023卷 247-259页

作者： Hao xu Junsheng Zeng Dongxiao Zhang BIC-ESAT EREand SKLTCSCollege of EngineeringPeking UniversityBeijing 100871P.R.China Institute of Applied Physics and Computational Mathematics Beijing 100088P.R.China Eastern Institute for Advanced Study Eastern Institute of TechnologyNingbo 315200ZhejiangP.R.China National Center for Applied Mathematics Shenzhen(NCAMS) Southern University of Science and TechnologyShenzhen 518055GuangdongP.R.China Department of Mathematics and Theories Peng Cheng LaboratoryShenzhen 518000GuangdongP.R.China

Data-driven discovery of partial differential equations(PDEs)has recently made tremendous progress,and many canonical PDEs have been discovered successfully for proof of ***,determining the most proper PDE without prior references remains challenging in terms of practical *** this work,a physics-informed information criterion(PIC)is proposed to measure the parsimony and precision of the discovered PDE *** proposed PIC achieves satisfactory robustness to highly noisy and sparse data on 7 canonical PDEs from different physical scenes,which confirms its ability to handle difficult *** PIC is also employed to discover unrevealed macroscale governing equations from microscopic simulation data in an actual physical *** results show that the discovered macroscale PDE is precise and parsimonious and satisfies underlying symmetries,which facilitates understanding and simulation of the physical *** proposition of the PIC enables practical applications of PDE discovery in discovering unrevealed governing equations in broader physical scenes.

关键词： process canonical proof

On Isodual Double Toeplitz Codes

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Journal of Systems Science & Complexity 2024年第5期37卷 2196-2206页

作者： SHI Minjia xu Li SOLÉ Patrick Key Laboratory of Intelligent Computing and Signal Processing Ministry of EducationSchool of Mathematical SciencesAnhui UniversityHefei 230601China State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of SciencesBeijing 100093China CNRS University of Aix MarseilleCentrale MarseilleI2MMarseille 13284France

Double Toeplitz(shortly DT)codes are introduced here as a generalization of double circulant *** authors show that such a code is isodual,hence formally self-dual(FSD).FSD codes form a far-reaching generalization of self-dual codes,the most important class of codes of rate ***-dual DT codes are characterized as double circulant or double ***,even binary DT codes are characterized as double *** examples obtained by exhaustive search show that the codes constructed have best-known minimum distance,up to one unit,amongst formally self-dual codes,and sometimes improve on the known *** q=2,the authors find four improvements on the best-known values of the minimum distance of FSD *** F4 an explicit construction of DT codes,based on quadratic residues in a prime field,performs equally *** authors show that DT codes are asymptotically good over ***,the authors construct DT codes arbitrarily close to the asymptotic Varshamov-Gilbert bound for codes of rate one half.

关键词： Double circulant codes double Toeplitz codes isodual codes formally self-dual codes

Linear Quadratic Optimal Control for Systems Governed by First-Order Hyperbolic Partial Differential Equations

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Journal of Systems Science & Complexity 2024年第1期37卷 230-252页

作者： xuE Xiaomin xu Juanjuan ZHANG Huanshui School of Control Science and Engineering Shandong UniversityJinan 250061China College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266000China

This paper focuses on linear-quadratic(LQ)optimal control for a class of systems governed by first-order hyperbolic partial differential equations(PDEs).Different from most of the previous works,an approach of discretization-then-continuousization is proposed in this paper to cope with the infinite-dimensional nature of PDE *** contributions of this paper consist of the following aspects:(1)The differential Riccati equations and the solvability condition of the LQ optimal control problems are obtained via the discretization-then-continuousization method.(2)A numerical calculation way of the differential Riccati equations and a practical design way of the optimal controller are ***,the relationship between the optimal costate and the optimal state is established by solving a set of forward and backward partial difference equations(FBPDEs).(3)The correctness of the method used in this paper is verified by a complementary continuous method and the comparative analysis with the existing operator results is *** is shown that the proposed results not only contain the classic results of the standard LQ control problem of systems governed by ordinary differential equations as a special case,but also support the existing operator results and give a more convenient form of computation.

关键词： Discretization-then-continuousization method first-order hyperbolic partial differential equations forward and backward partial difference equations linear quadratic optimal control.