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Acta Mathematica Scientia 2022年第3期42卷 825-846页

作者： jie jiang Innovation Academy for Precision Measurement Science and Technology CASWuhan 430071China

In this paper we consider the initial Neumann boundary value problem for a degenerate Keller-Segel model which features a signal-dependent non-increasing motility *** main obstacle of analysis comes from the possible degeneracy when the signal concentration becomes *** the current work,we are interested in the boundedness and exponential stability of the classical solution in higher *** the aid of a Lyapunov functional and a delicate Alikakos-Moser type iteration,we are able to establish a time-independent upper bound of the concentration provided that the motility function decreases *** we further prove the uniform-in-time boundedness of the solution by constructing an estimation involving a weighted ***,thanks to the Lyapunov functional again,we prove the exponential stabilization toward the spatially homogeneous steady *** boundedness result improves those in[1]and the exponential stabilization is obtained for the first time.

关键词： Classical solution boundedness exponential stabilization degeneracy Keller-Segel models

Strong Cosmic Censorship in accelerating spacetime

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Science China(Physics,Mechanics & Astronomy) 2023年第8期66卷 51-56页

作者： Ming Zhang jie jiang Department of Physics Jiangxi Normal UniversityNanchang 330022China College of Education for the Future Beijing Normal UniversityZhuhai 519087China

It has been established that Strong Cosmic Censorship Conjecture(SCCC)is respected by an asymptotically flat black hole with charge,but violated by a charged asymptotically de Sitter black *** studied the instability of the Cauchy horizon for an accelerating black hole in Einstein theory conformally coupled with a scalar *** black hole is uncharged while having inner,outer,and acceleration *** the limit of vanishing acceleration,denoted by A→0,it becomes asymptotically flat and extremal,with its acceleration horizon vanishing as *** exploring the perturbation of the massless scalar field upon the accelerating black hole,whose decay rate is governed by the quasinormal mode spectra,we show that the SCCC is violated in the near-extremal regime and also in the A→0+*** result is the first observation of a black hole violating the SCCC in an almost asymptotically Minkowskian flat regime,as well as the first example of a black hole violating the SCCC with neither charge nor rotation.

关键词： Strong Cosmic Censorship accelerating black hole Cauchy horizon

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The Roles of Barotropic Instability and the Beta Effect in the Eyewall Evolution of Tropical Cyclones

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Advances in Atmospheric Sciences 2022年第11期39卷 1800-1815页

作者： jie jiang Yuqing WANG Department of Atmospheric Sciences University of Hawaii at Manoa HonoluluHawaii 96822USA International Pacific Research Center and Department of Atmospheric Sciences University of Hawaii at Manoa HonoluluHawaii 96822USA

Diabatic heating by convection in the eyewall often produces an annular region of high potential vorticity(PV)around the relatively low PV eye in a strong tropical cyclone(TC).Such a PV ring is barotropically unstable and can encourage the exponential growth of PV *** this study,such instability and the subsequent nonlinear evolution of three TC-like vortices having PV rings with different degrees of hollowness on an f-plane are first examined using an unforced,inviscid shallow-water-equation *** show that the simulated eyewalls evolve similarly to those in the nondivergent barotropic *** is also found that the polygonal eyewall structure can be decomposed into vortex Rossby waves(VRWs)of different wavenumbers with different amplitudes,allowing for wave-wave interactions to produce complicated behaviors of mesovortices in the TC *** same set of PV rings has been examined on a *** the beta effect has been rendered unimportant to the eyewall evolution due to the relatively small scale of the inner-core circulation,this study shows that the beta effect may erode the coherent structure of mesovortices in the eyewall of an initially hollow PV-ring *** modeled on the beta-plane with a greater beta parameter tend to experience an earlier breakdown and enhanced radial gradients of the basic-state(azimuthally mean)angular velocity,followed by wave-wave,wave-flow interactions,leading to earlier merger and axisymmetrization *** result implies that the beta effect could be one of the forcings that shorten the lifetime of quasi-steady mesovortices in the eyewall of real TCs.

关键词： tropical cyclones vortex rossby waves barotropic instability Beta effect

China’s high-resolution optical remote sensing satellites and their mapping applications

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Geo-Spatial Information Science 2021年第1期24卷 85-94,I0011页

作者： Deren Li Mi Wang jie jiang State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina School of Geomatics and Urban Spatial Informatics Beijing University of Civil Engineer and ArchitectureBeijingChina

Since the beginning of the twenty-first century,several countries have made great efforts to develop space remote sensing for building a high-resolution earth observation *** the great attention of the government and the guidance of the major scientific and technological project of the high-resolution earth observation system,China has made continuous breakthroughs and progress in high-resolution remote sensing imaging *** development of domestic high-resolution remote sensing satellites shows a vigorous trend,and consequently,a relatively stable and perfect high-resolution earth observation system has been *** development of high-resolution remote sensing satellites has greatly promoted and enriched modern mapping technologies and *** this paper,the development status,along with mapping modes and applications of China’s high-resolution remote sensing satellites are reviewed,and the development trend in high-resolution earth observation system for global and ground control-free mapping is discussed,providing a reference for the subsequent development of high-resolution remote sensing satellites in China.

关键词： High-resolution optical remote sensing satellite satellite constellation mapping mode global mapping

Regularized Methods for a Two-Stage Robust Production Planning Problem and its Sample Average Approximation

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Journal of the Operations Research Society of China 2023年第3期11卷 595-625页

作者： jie jiang Zhi-Ping Chen College of Mathematics and Statistics Chongqing UniversityChongqing401331China School of Mathematics and Statistics Xi'an Jiaotong UniversityCenter for Optimization Technique and Quantitative FinanceXi'an International Academy for Mathematics and Mathematical TechnologyXi'an 710049ShaanxiChina

In this paper,we consider a two-stage robust production planning model where the first stage problem determines the optimal production quantity upon considering the worst-case revenue generated by the uncertain future demand,and the second stage problem determines the possible demand of consumers by using a utility-based model given the production quantity and a realization of the random *** derive an equivalent single-stage reformulation of the two-stage ***,it fails the convergence analysis of the sample average approximation(SAA)approach for the reformulation *** we develop a regularized approximation of the second stage problem and derive its closed-form *** then present conditions under which the optimal value and the optimal solution set of the proposed SAA regularized approximation problem converge to those of the single-stage reformulation problem as the regularization parameter shrinks to zero and the sample size tends to ***,some preliminary numerical examples are presented to illustrate our theoretical results.

关键词： Production planning Utility function SAA Complementarity problem Regularized method

Co/CoO heterojunction rich in oxygen vacancies introduced by O_(2) plasma embedded in mesoporous walls of carbon nanoboxes covered with carbon nanotubes for rechargeable zinc-air battery

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Carbon Energy 2024年第7期6卷 14-25页

作者： Leijun Ye Weiheng Chen Zhong-jie jiang Zhongqing jiang Key Laboratory of Optical Field Manipulation of Zhejiang Province Department of PhysicsZhejiang Sci-Tech UniversityHangzhouChina Department of Mechanical Engineering Ningbo University of TechnologyNingboChina Guangzhou Key Laboratory for Surface Chemistry of Energy Materials Guangdong Engineering and Technology Research Center for Surface Chemistry of Energy MaterialsCollege of Environment and EnergySouth China University of TechnologyGuangzhouChina

Herein,Co/CoO heterojunction nanoparticles(NPs)rich in oxygen vacancies embedded in mesoporous walls of nitrogen-doped hollow carbon nanoboxes coupled with nitrogen-doped carbon nanotubes(P-Co/CoOV@NHCNB@NCNT)are well designed through zeolite-imidazole framework(ZIF-67)carbonization,chemical vapor deposition,and O_(2) plasma *** a result,the threedimensional NHCNBs coupled with NCNTs and unique heterojunction with rich oxygen vacancies reduce the charge transport resistance and accelerate the catalytic reaction rate of the P-Co/CoOV@NHCNB@NCNT,and they display exceedingly good electrocatalytic performance for oxygen reduction reaction(ORR,halfwave potential[EORR,1/2=0.855 V *** hydrogen electrode])and oxygen evolution reaction(OER,overpotential(η_(OER,10)=377mV@10mA cm^(−2)),which exceeds that of the commercial Pt/C+RuO_(2) and most of the formerly reported ***,both the aqueous and flexible foldable all-solid-state rechargeable zinc-air batteries(ZABs)assembled with the P-Co/CoOV@NHCNB@NCNT catalyst reveal a large maximum power density and outstanding long-term cycling ***-principles density functional theory calculations show that the formation of heterojunctions and oxygen vacancies enhances conductivity,reduces reaction energy barriers,and accelerates reaction kinetics *** work opens up a new avenue for the facile construction of highly active,structurally stable,and cost-effective bifunctional catalysts for ZABs.

关键词： heterojunction oxygen evolution/reduction reaction oxygen vacancies rechargeable zinc–air battery three‐dimensional nitrogen‐doped hollow carbon nanoboxes

Passive inter-modulation scattering analysis of reflector considering contact nonlinearity

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Chinese Journal of Aeronautics 2013年第2期26卷 463-469页

作者： jiang jie Li Tuanjie Liu Yicai School of Electromechanical Engineering Xidian University

Passive inter-modulation （PIM） is a form of nonlinear distortion caused by the inherent nonlinearities of the passive devices and components in RF/microwave system. It will degenerate the performance of communication system with broad-band channel and high-sensitivity receiver. Therefore, it is necessary to construct a model to simulate this process in order to predict the level of PIM. This paper is aimed at constructing some plate models with one-dimensional and two-dimensional contact nonlinearity sections illuminated by two-tone waves, and calculating the scattered field at a fixed-point in space using time-domain physical optics method. By taking fast Fourier transform （FFT）, we get the spectrum of the scattered field and then analyze the generated PIM products. At the end of this paper, some numerical examples are presented to show the influence rules of the relative factors on PIM. The results indicate the variation of the level of PIM with the number of the nonlinear regions, the nonlinear spacing, and the incident power levels.

关键词： Contact nonlinearity Nonlinear distortion Passive inter-modulation Reflector antennas Scattered field Time-domain physical optics

Angel: a new large-scale machine learning system

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National Science Review 2018年第2期5卷 216-236页

作者： jie jiang Lele Yu Jiawei jiang Yuhong Liu Bin Cui Key Lab of High Confidence Software Technologies (MOE) School of EECSPeking University

Machine Learning(ML) techniques now are ubiquitous tools to extract structural information from data collections. With the increasing volume of data, large-scale ML applications require an efficient implementation to accelerate the performance. Existing systems parallelize algorithms through either data parallelism or model parallelism. But data parallelism cannot obtain good statistical efficiency due to the conflicting updates to parameters while the performance is damaged by global barriers in model parallel methods. In this paper, we propose a new system, named Angel, to facilitate the development of large-scale ML applications in production environment. By allowing concurrent updates to model across different groups and scheduling the updates in each group, Angel can achieve a good balance between hardware efficiency and statistical efficiency. Besides, Angel reduces the network latency by overlapping the parameter pulling and update computing and also utilizes the sparseness of data to avoid the pulling of unnecessary parameters. We also enhance the usability of Angel by providing a set of efficient tools to integrate with application pipelines and provisioning efficient fault tolerance mechanisms. We conduct extensive experiments to demonstrate the superiority of Angel.

关键词： machine learning distributed system algorithms big data analytics

Discrete Approximation and Convergence Analysis for a Class of Decision-Dependent Two-Stage Stochastic Linear Programs

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Journal of the Operations Research Society of China 2024年第3期12卷 649-679页

作者： jie jiang Zhi-Ping Chen College of Mathematics and Statistics Chongqing UniversityChongqing401331China School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an710049ShaanxiChina Center for Optimization Technique and Quantitative Finance Xi’an International Academy for Mathematics and Mathematical TechnologyXi’an710049ShaanxiChina

Customary stochastic programming with recourse assumes that the probability distribution of random parameters is independent of decision *** studies demonstrated that stochastic programming models with endogenous uncertainty can better reflect many real-world activities and applications accompanying with decision-dependent *** this paper,we concentrate on a class of decision-dependent two-stage stochastic programs(DTSPs)and investigate their discrete *** develop the discrete approximation methods for DTSPs,we first derive the quantitative stability results for *** on the stability conclusion,we examine two discretization schemes when the support set of random variables is bounded,and give the rates of convergence for the optimal value and optimal solution set of the discrete approximation problem to those of the original *** we extend the proposed approaches to the general situation with an unbounded support set by using the truncating *** an illustration of our discretization schemes,we reformulate the discretization problems under specific structures of the decision-dependent ***,an application and numerical results are presented to demonstrate our theoretical results.

关键词： Stochastic programming Decision-dependence Discrete approximation Stability Convergence rate

A Non-axisymmetric Spherical α~2-Dynamo

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Chinese Journal of Astronomy and Astrophysics 2006年第2期6卷 227-236页

作者： jie jiang Jing-Xiu Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Using the Chebyshev-tau method, the generation of oscillatory nonaxisymmetric stellar magnetic fields by the α^2-dynamo is studied in spherical geometry. Following the boundary conditions given by Schubert ＆ Zhang, the spherical α^2-dynamo consists of a fully convective spherical shell with inner radius ri and outer radius ro. A comparison of the critical dynamo numbers of axisymmetric and φ-dependent modes for different thicknesses of the convective shell and different α- profiles leads to the following qualitative results：（i） when the angular factor of α- profile is sin^n θ cosθ （n= 1, 2, 4） the solutions of the α^2dynamo are oscillatory and non-axisymmetric, （ii） the thinner the convective shell, the more easily is the nonaxisymmetric mode excited and the higher is the latitudinal wave number, （iii） the thickness of the outer convective shell has an effect on the symmetries of the magnetic fields.

关键词： stars: magnetic fields - methods: numerical