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littlewood-Paley theory on metric spaces with non doubling measures and its applications

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Science China Mathematics 2015年第5期58卷 983-1004页

作者： TAN ChaoQiang li ji Department of Mathematics Shantou University Department of Mathematics Macquarie University

The purpose of this paper is to extend the littlewood-Paley theory to a geometrically doubling metric space with a non-doubling measure satisfying a weak growth condition. Moreover, we prove that our setting mentioned above, is equivalent to the one introduced and studied by HytSnen （2010） in his remarkable framework, i.e., the geometrically doubling metric space with a non-doubling measure satisfying a so-called upper doubling condition. As an application, we obtain the T1 theorem in this more general setting. Moreover, the Gaussian measure is also discussed.

关键词： non-homogeneous space upper doubling weak growth condition littlewood-Paley theory

Optimal Transportation for Generalized Lagrangian

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Chinese Annals of Mathematics,Series B 2017年第3期38卷 857-868页

作者： ji li jianlu ZHANG Department of Mathematics Nanjing University 22 Hankou Road Nanjing 210093 China.

This paper deals with the optimal transportation for generalized Lagrangian L = L（x, u, t）, and considers the following cost function： c（x, y） = inf x（0）=x x（1）=y u∈U∫0^1 L（x（s）, u（x（s）, s）, s）ds, where U is a control set, and x satisfies the ordinary equation x（s） = f（x（s）, u（x（s）, s））.It is proved that under the condition that the initial measure μ0 is absolutely continuous w.r.t. the Lebesgue measure, the Monge problem has a solution, and the optimal transport map just walks along the characteristic curves of the corresponding Hamilton-Jacobi equation：Vt（t, x）＋ sup u∈U = 0,V（0, x） = Φ0（x）.

关键词： Optimal control Hamilton-Jacobi equation Characteristic curve Viscosity solution Optimal transportation Kantorovich pair Initial transport measure

Symmetry Reduction and Cauchy Problems for a Class of Fourth-Order Evolution Equations

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Communications in Theoretical Physics 2008年第7期50卷 31-38页

作者： li ji-Na ZHANG Shun-li Center for Nonlinear Studies Department of Mathematics Northwest University Xi＇an 710069 China Center of Nonlinear Science Ningbo University Ningbo 315211 China

We exploit higher-order conditional symmetry to reduce initial-value problems for evolution equations toCauchy problems for systems of ordinary differential equations (ODEs).We classify a class of fourth-order evolutionequations which admit certain higher-order generalized conditional symmetries (GCSs) and give some examples to showthe main reduction *** reductions cannot be derived within the framework of the standard lie approach,which hints that the technique presented here is something essential for the dimensional reduction of evolu tion equations.

关键词： fourth-order evolution equation generalized conditional symmetry Cauchy problem

Bifurcations of Travelling Wave Solutions for a Two-Component Camassa-Holm Equation

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Acta Mathematica Sinica,English Series 2008年第8期24卷 1319-1330页

作者： ji Bin li Yi Shen li Center for Nonlinear Science Studies Kunming University of Science and Technology Kunming 650093 P. R. China Department of Mathematics Zhejiang Normal University Jinhua 321004 P. R. China Department of Mathematics and Center of Nonlinear Science University of Science and Technology of China Hefei 230026 P. R. China

By using the method of dynamical systems to the two-component generalization of the Camassa-Holm equation, the existence of solitary wave solutions, kink and anti-kink wave solutions, and uncountably infinite many breaking wave solutions, smooth and non-smooth periodic wave solutions is obtained. Under different parametric conditions, various sufficient conditions to guarantee the existence of the above solutions are given. Some exact explicit parametric representations of travelling wave solutions are listed.

关键词： solitary wave kink wave solution periodic wave solution breaking wave solution smooth- ness of wave

A sensorless efficiency test system for a high-speed permanent magnet synchronous motor

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 390-399页

作者： li ji Yixiang SHAO Sujie GAO College of Energy and Electrical Engineering Hohai UniversityNanjing 210098China NARI Group Corporation(State Grid Electric Power Research Institute) Nanjing 211102China State Grid Xin Yuan Company limited Beijing 100000China

We present a sensorless efficiency test system with energy recovery for a high-speed permanent magnet synchronous motor(PMSM). In the system, two identical high-speed PMSMs are used as the motor under test(MUT)and the load machine(LM),respectively.A new sensorless vector control(VC) method based on a hypothetical reference frame is presented to control both the MUT and the ***,a regenerating unit is used to implement energy circulation to save *** were carried out on a prototype, with a digital controller based on the TMS320 F28335, to verify the adequacy of the sensorless VC *** a result,the efficiency test system achieves the load test at the speed of 21000 r/min without any reduction equipment. During the test, the energy regenerated by the LM could be fed back to the MUT by the regenerating unit, and 81.31% electrical power was *** addition, with the proposed sensorless VC method,both the MUT and the LM can work at i_d = 0 without a position sensor.

关键词： Distributed generation High-speed permanent magnet synchronous motor(PMSM) Sensorless control Energy saving

Modeling calving process of glacier with dilated polyhedral discrete element method

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Acta Oceanologica Sinica 2021年第7期40卷 159-169页

作者： Lu liu ji li Qizhen Sun Chunhua li Sue Cook Shunying ji State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China National Marine Environmental Forecasting Center Beijing 100081China Institute for Marine and Antarctic Studies University of TasmaniaHobart 7001Australia

Mass loss caused by glacier calving is one of the direct contributors to global sea level *** calving laws are required for accurate modelling of ice sheet mass *** continuous and discontinuous methods have been used for glacial calving *** this study,the discrete element method(DEM)based on dilated polyhedral elements is introduced to simulate the calving process of a tidewater *** polyhedrons can be obtained from the Minkowski sum of a sphere and a core *** elements can be utilized to generate a continuum ice material,where the interaction force between adjacent elements is modeled by constructing bonds at the joints of the common faces.A hybrid fracture model considering fracture energy is *** viscous creep behavior of glaciers on long-term scales is not *** applying buoyancy and gravity to the modelled glacier,DEM results show that the calving process is caused by cracks which are initialized at the top of the glacier and spread to the *** results demonstrate the feasibility of using the dilated polyhedral DEM method in glacier simulations,additionally allowing the fragment size of the breaking fragments to be *** relationship between crack propagation and internal stress in the glacier is analyzed during calving *** the analysis of the Mises stress and the normal stress between the elements,it is found that geometric changes caused by the glacier calving lead to the redistribution of the *** tensile stress between the elements is the main influencing factor of glacier ice *** addition,the element shape,glacier base friction and buoyancy are studied,the results show that the glacier model based on the dilated polyhedral DEM is sensitive to the above conditions.

关键词： glacier calving discrete element method dilated polyhedral element bond and fracture model

Vortex lines and Monopoles in Electrically Conducting Plasmas

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Communications in Theoretical Physics 2009年第2期51卷 335-340页

作者： WANG ji-Biao REN ji-Rong li Ran Institute of Theoretical Physics Lanzhou University Lanzhou 730000 China

Based on the φ-mapping topological current theory and the decomposition of gauge potential theory, the vortex lines and the monopoles in electrically conducting plasmas are studied. It is pointed out that these two topological structures respectively inhere in two-dimensional and three-dimensional topological currents, which can be derived from the same topological term n^→·（Эin^→×Эjn^→）, and both these topological structures axe characterized by the φ-mapping topological numbers-Hopf indices and Brouwer degrees. Furthermore, the spatial bifurcation of vortex lines and the generation and annihilation of monopoles are also discussed. At last, we point out that the Hopf invaxiant is a proper topological invaxiant to describe the knotted solitons.

关键词： plasma vortex line monopole

Prevalence of pulmonary embolism at autopsy among elderly patients in a Chinese general hospital

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Journal of Geriatric Cardiology 2016年第11期13卷 894-898页

作者： ji-li YUN Xiao-Ying li Medical School of Chinese PLA General Hospital Beijing China Department of Geriatric Cardiology Chinese PLA General Hospital Beijing China

Objectives To investigate the prevalence and characteristics of pulmonary embolism （PE） at autopsy in a Chinese general hospital over a period of 10 years, and to evaluate the antemortem achievement of the prophylaxis, diagnosis, and treatment of PE. Methods All medical records of deaths from the West Branch of the Chinese People＇s liberation Army （PLA） General Hospital were retrospectively re- viewed, for the period of January 1, 2006 to December 31, 2015. Cases in which autopsies had been performed were identified and further analyzed. The numbers and detailed characteristics of patients who had PEs were noted. Prophylactic measures, along with diagnosis and treatment of PE, were recorded, if performed. Results During the 10-year period, 1057 patients died in the study hospital and 278 necrop- sies were performed （autopsy rate： 26.3%）. Nine patients were found to have PE （3.2%）, and in seven of these patients （2.5%）, the PE was considered to be fatal. Embolisms were found in the trunk and bilateral main branches of the pulmonary artery tree in all seven of the fatal PE cases. Right intracardiac thrombosis was detected in five of the nine PE patients （55.6%）. All patients with PE had been hospitalized in medical departments, and only one had undergone surgery during hospitalization. Antemortem prophylaxis was performed in two of the nine PE cases （22.2%）. None of the 9 patients had received a clinical diagnosis of PE before death. Conclusions The incidence of and death rate associated with PE may vary among different races and regions. Continuous monitoring of PE by means of necropsy in certain representative medical institutions is necessary.

关键词： Autopsy Epidemiology Pulmonary embolism

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靶机用红外指示器的性能提升研究

火工品 2025年第1期 13-17页

作者：李积珍冯帅贾博李钊杨军李晓平高艳侠西安北方庆华机电有限公司陕西西安710025

针对传统靶机用红外指示器在辐射强度、稳定性和持续时间方面存在的不足,对指示器的药剂配方、装药结构和装药密度进行了优化,设计了一种新型红外指示器。通过环境试验和发火试验,验证了新型红外指示器在经受振动、发射冲击和温度冲击... 详细信息

针对传统靶机用红外指示器在辐射强度、稳定性和持续时间方面存在的不足,对指示器的药剂配方、装药结构和装药密度进行了优化,设计了一种新型红外指示器。通过环境试验和发火试验,验证了新型红外指示器在经受振动、发射冲击和温度冲击后的可靠性,并测试了其红外辐射性能。结果表明:新型红外指示器在中波段(3.6~4.9μm)的辐射强度达到1200 W/sr,稳定辐射时间达到120 s,离散度控制在90 W/sr以内,且无团聚物现象,有效模拟了轻型战斗机的红外辐射特征。本研究的优化设计显著提升了靶机用红外指示器的性能,为提高空军部队实弹打靶训练的模拟真实性和安全性提供了技术支持。

关键词：靶机红外指示器红外辐射离散度