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Pulsed dynamic electrolysis enhanced PEMWE hydrogen production:Revealing the effects of pulsed electric fields on protons mass transport and hydrogen bubble escape

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Journal of Energy Chemistry 2025年第1期100卷 201-214页

作者： Xuewei Zhang Wei Zhou Yuming Huang liang Xie Tonghui li Huimin Kang lijie Wang Yang Yu Yani Ding junfeng li Jiaxiang Chen Miaoting Sun Shuo Cheng Xiaoxiao Meng Jihui Gao Guangbo Zhao School of Energy Science and Engineering Harbin Institute of Technology China Datang Technology Innovation Co. Ltd

The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis （PEMWE） emerging as the preeminent pathway for hydrogen *** remarkable advancements in this field,confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable *** impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles *** address these challenges,we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis *** to constant voltage electrolysis (hydrogen production rate:51.6 m L h-1,energy consumption:5.37 kWh Nm-3H2),this strategy (hydrogen production rate:66 m L h-1,energy consumption:3.83 kWh Nm-3H2) increases the hydrogen production rate by approximately 27%and reduces the energy consumption by about 28%.Furthermore,we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic （PV） system designed for outdoor operation,successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 *** combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism:pulsed dynamic electrolysis （PDE） dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode *** such,PDE-enhanced PEMWE represents a synergistic advancement,concurrently enhancing both the hydrogen generation reaction and associated transport *** promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.

关键词： Electrolysis

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A practical parallel preprocessing strategy for 3D numerical manifold method

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Science China(Technological Sciences) 2022年第12期65卷 2856-2865页

作者： YANG YongTao li junfeng State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

Over the past three decades,the numerical manifold method(NMM)has attracted many researchers from geotechnical community because it unifies the solutions of continuous and discontinuous problems in the same ***,due to the lack of ready-made preprocessing tools,the development of three dimensional NMM(3DNMM)is still limited.A practical strategy to generate the discretized models for a 3DNMM analysis is *** the proposed strategy,regular hexahedral meshes are uniformly deployed to construct the mathematical cover *** physical meshes including the joints,material interfaces,and problem domain boundaries are adopted to cut the mathematical cover system into physical cover system and manifold elements(MEs).To improve the efficiency of the proposed strategy,the Intel threading building blocks(TBB)parallel library for CPU paralleling is *** typical examples are adopted to validate the proposed *** results show that the proposed strategy can effectively generate the discretized 3D models of some geotechnical problems for 3DNMM *** proposed strategy deserves a further investigation.

关键词： three-dimensional numerical manifold method 3D cutting parallel programming physical system encoding

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On 4-order Schrodinger operator and Beam operator

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Frontiers of Mathematics in China 2019年第6期14卷 1197-1211页

作者： Dan li junfeng li School of Mathematical Sciences Beijing Normal UniversityBeijing 100875China School of Mathematical Sciences Dalian University of TechnologyDalian 116024China

Wc show that there is no localization for the 4-order Schrodinger operator Jt,Af and Bearn operator 38%more precisely,on the one hand,we show that the 4-order Schrodinger operator Atf, does not converge pointwise to z... 详细信息

关键词： 4-Order Schrodinger operator Beam operator localization Sobolev space

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Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

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Chinese Journal of Aeronautics 2024年第3期37卷 181-193页

作者： Zhao li Hengnian li Fanghua JIANG junfeng li State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary *** Earth’s oblateness perturbation and shadow are taken into *** is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational *** this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate *** on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged *** polynomial regression models are trained on the training dataset and are regarded as the costate *** the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any ***,all these computations onboard are *** simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

关键词： Low thrust Orbital transfer Trajectory optimization Guidance Indirect method Orbital averaging Machine learning Geostationary satellites

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Carleson Measures on the Weighted Bergman Spaces with Békollé Weights

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Chinese Annals of Mathematics,Series B 2021年第4期42卷 583-600页

作者： Cezhong TONG junfeng li Institute of Mathematics Hebei University of TechnologyTianjin 300401China Depaxtment of Mathematical Sciences Tsinghua UniversityBeijing 100084China

In this paper,the authors characterize Carleson measures for the weighted Bergman spaces with Békollé weights on the unit *** apply the Carleson embedding theorem to study the properties of Toeplitz-type operators a... 详细信息

关键词： Békolléweight Bergman space Carleson measure Toeplitz operator Composition operator

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Fuel consumption for interplanetary missions of solar sailing

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Science China(Physics,Mechanics & Astronomy) 2014年第3期57卷 521-531页

作者： GONG ShengPing li junfeng School of Aerospace Tsinghua University

The orbits of solar sails can be changed by adjusting the sail’s attitude through external control *** resulting momentum will be changed,either provided by a typical attitude control subsystem or by a propellantless *** paper investigates the extra momentum input and fuel consumption for a typical attitude control *** minimum-time transfer trajectories are designed for two rendezvous missions using both indirect and direct methods,generating continuous and discrete attitude histories,*** results show that the momentum variation is almost wholly due to the solar radiation *** feasibility of using tip-mounted microthrusters for attitude control is *** results show that less than0.1 kg of propellant are required for an interplanetary transfer mission when pulsed plasma thrusters with a specific impulse of700 s and a thrust of 150 mN are mounted at the tip of a 20 m square solar *** fuel consumptions of two transfer missions indicate that a tip-mounted pulsed plasma thruster is a viable technique for the attitude control of a solar sail.

关键词： solar sail interplanetary transfer fuel consumption

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Sharp weak bounds for n-dimensional fractional Hardy operators

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Frontiers of Mathematics in China 2018年第2期13卷 449-457页

作者： Haixia YU junfeng li Laboratory of Mathematics and Complex Systems(Beijing Normal University) Ministry of EducationSchool of Mathematical SciencesBeijing Normal UniversityBeijing 100875China

We obtain the operator norms of the n-dimensional fractional Hardy operator Hα（0 〈 α 〈 n） from weighted Lebesgue spaces Lp｜x｜p（R^n） to weighted weak Lebesgue spacesLq,∞｜x｜β（R^n）.

关键词： Sharp weak bound fractional Hardy operator Lebesgue space with power weight

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The least square particle finite element method for simulating large amplitude sloshing flows

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Acta Mechanica Sinica 2008年第3期24卷 317-323页

作者： Bo Tang junfeng li Tianshu Wang School of Aerospace Tsinghua University Beijing 100084 China

Large amplitude sloshing in tanks is simulated by the least square particle finite element method （LSPFEM） in this paper. The least square finite element method （LSFEM） is employed to spatially discrete the Navier-Stokes equations, and to avoid the stabilization issues due to the incompressibility condition for equal-order interpolation of the velocity and the pressure, as usually used in Galerkin method to satisfy the well-known LBB condition. The LSPFEM also uses the Lagrangian description to model the motion of nodes （particles）. A mesh which connects these nodes is constructed by a triangulation algorithm to avoid the mesh distortion. A quasi a-shapes algorithm is used to identify the free surface boundary. The nodes are viewed as particles which can freely move and even separate from the main fluid domain. Finally this method is used to study the large amplitude sloshing evolution in two dimensional tanks. The results are compared with those obtained by Flow-3d with good agreement.

关键词： Incompressible fluid Least square finiteelement method Lagrangian description Boundaryrecognition Collapse Impact

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Solution set on the natural satellite formation orbits under first-order earth's non-spherical perturbation

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Acta Mechanica Sinica 2005年第5期21卷 503-510页

作者： Humei Wang Wei Yang junfeng li School of Aerospace Tsinghua University Beijing100084 China

Using the reference orbital element approach, the precise governing equations for the relative motion of formation flight are formulated. A number of ideal formations with respect to an elliptic orbit can be designed based on the relative motion analysis from the equations. The features of the oscillating reference orbital elements are studied by using the perturbation theory. The changes in the relative orbit under perturbation are divided into three categories, termed scale enlargement, drift and distortion respectively. By properly choosing the initial mean orbital elements for the leader and follower satellites, the deviations from originally regular formation orbit caused by the perturbation can be suppressed. Thereby the natural formation is set up. It behaves either like non-disturbed or need little control to maintain. The presented reference orbital element approach highlights the kinematics properties of the relative motion and is convenient to incorporate the results of perturbation analysis on orbital elements. This method of formation design has advantages over other methods in seeking natural formation and in initializing formation.

关键词： Orbital mechanics . Satellite formation flight .Orbital elements . Reference orbital elements . Perturbation

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Multiscale models of compact bone

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International Journal of Biomathematics 2016年第3期9卷 271-292页

作者： junfeng li Shugang li School of Mathematics and Statistics Central China Normal University Wuhan 430079 P. R. China

This work is concerned about multiscale models of compact bone. We focus on the lacuna-canalicular system. The interstitial fluid and the ions in it are regarded as sol- vent and others are treated as solute. The system has the characteristic of solvation process as well as non-equilibrium dynamics. The differential geometry theory of sur- faces is adopted. We use this theory to separate the macroscopic domain of solvent from the microscopic domain of solute. We also use it to couple continuum and discrete descriptions. The energy functionals are constructed and then the variational principle is applied to the energy functionals so as to derive desirable governing equations. We consider both long-range polar interactions and short-range nonpolar interactions. The solution of governing equations leads to the minimization of the total energy.

关键词： Compact bone lacuna-canalicular system multiscale Laplace-Beltramiequation Poisson Boltzmann equation.

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