检索结果-南通市图书馆

Digital twin model of gas turbine and its application in warning of performance fault

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第3期36卷 449-470页

作者： Minghui HU Ya HE Xinzhi LIN Ziyuan LU Zhinong JIANG Bo MA Key Lab of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China beijing Key Laboratory of High-end Mechanical Equipment Health Monitoring and Self-Recovery Beijing University of Chemical TechnologyBeijing 100029China capital Aerospace Machinery Corporation Limited Beijing 100076China Hangli(Group)Industrial Co. LtdChengdu 611936China

The digital twin-driven performance model provides an attractive option for the warn gas-path faults of the gas ***,three technical difficulties need to be solved:(1)low modeling precision caused by individual differences between gas turbines,(2)poor solution efficiency due to excessive iterations,and(3)the false alarm and missing alarm brought by the traditional fixed threshold *** paper proposes a digital twin model-based early warning method for gas-path faults that breaks through the above obstacles from three ***,a novel performance modeling strategy is proposed to make the simulation effect close to the actual gas turbine by fusing the mechanism model and measurement ***,the idea of controlling the relative accuracy of model parameters is *** introduction of an error module to the existing model can greatly shorten the modeling *** third solution focuses on the early warning based on the digital twin model,which self-learns the alarm threshold of the warning feature of gas-path parameters using the kernel density *** proposed method is utilized to analyze actual measured data of LM2500+,and the results verify that the new-built digital model has higher accuracy and better *** comparisons show that the proposed method shows evident superiority in early warning of performance faults for gas turbines over other methods.

关键词： Gas turbine Digital twin model Gas-path fault warning Deviation degree analysis Performance simulation

Agriculture Insurance in China:History,Experience,and Lessons Learned

在线全文

学校读者我要写书评

暂无评论

International Journal of Disaster Risk Science 2011年第2期2卷 10-22页

作者： Ming Wang Peijun Shi Tao Ye Min Liu Meiqin Zhou State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China Key Laboratory of Environmental Change and Natural Disasters Ministry of Education of ChinaBeijing Normal UniversityBeijing 100875China Academy of Disaster Reduction and Emergency Management Ministry of Civil Affairs and Ministry of Education of ChinaBeijing 100875China

The development of agriculture and the rural economy play a crucial role in China’s socioeconomic system. Agriculture insurance has become key in ensuring the growth of agriculture and stabilizing farmers’ income when faced with natural disasters. The focus of this article is the history of the development of Chinese agriculture insurance since the 1980 s and the trial of a new agriculture insurance launched in 2007, the policy details implemented in selected provinces, and the operation models. Using results from an investigation and field survey conducted since 2007 in Hunan Province, this article analyzes the performance and effects of this agriculture insurance trial run from the perspectives of different participating stakeholders, and with an emphasis on the program’s four principles. The experience and lessons learned are summarized, followed by recommendations on how to ensure the smooth operation and sustainable development of this new agriculture insurance program.

关键词： insurance income agriculture

COMPRESSIBLE NON-ISENTROPIC BIPOLAR NAVIER-STOKES-POISSON SYSTEM IN R^3

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2011年第6期31卷 2169-2194页

作者：肖玲李海梁杨彤邹晨 Institute of Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Department of Mathematics Capital Normal University Department of Mathematics City University of Hong Kong Department of Mechanics and Aerospace Engineering Peking University

The compressible non-isentropic bipolar Navier-Stokes-Poisson （BNSP） sys- tem is investigated in R3 in the present paper, and the optimal time decay rates of global strong solution are shown. For initial data being a perturbation of equilibrium state in Hl（R3）（R3） for 1 〉 4 and s E （0, 1], it is shown that the density and temperature for each charged particle （like electron or ion） decay at the same optimal rate （1 ＋ t）-3/4, but the momentum for each particle decays at the optimal rate （1 ＋ t）-1/4-3/2 which is slower than the rate （1 ＋ t）-3/4-3/2 for the compressible Navier-Stokes （NS） equations [19] for same initial data. However, the total momentum tends to the constant state at the rate （1 ＋t）-3/4 as well, due to the interplay interaction of charge particles which counteracts the influence of electric field.

关键词： Non-isentropic bipolar Navier-Stokes Poisson system optimal time decay rate

Resonant Scattering of Gravitational Waves with Electromagnetic Waves

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2023年第10期40卷 1-5页

作者：闫若帝刘润球 Department of Physics Beijing Normal UniversityBeijing 100875China Institute of Applied Mathematics Morningside Center of MathematicsLSSCAcademy of Mathematics and System ScienceChinese Academy of SciencesBeijing 100190China.

A certain class of exact solutions of Einstein Maxwell spacetime in general relativity is discussed to demonstrate that at the level of theory,when certain parametric resonance condition is met,the interaction of electromagnetic field with a gravitational wave will display certain Lyapunov instability and lead to exponential amplification of a gravitational wave train described by certain Newman-Penrose component of the Weyl *** some way akin to a free electron laser in electromagnetic theory,by the conversion of electromagnetic energy into gravitational energy in a coherent way,the feasibility of generating a pulsed-laser-like intense beam of gravitational wave is displayed.

关键词： Penrose generating exponential

New pattern Zn-Al-Mg-RE coating technics for steel structure sustainable design

在线全文

学校读者我要写书评

暂无评论

Journal of Central South university 2005年第S2期14卷 211-214页

作者：刘燕徐滨士朱子新栗卓新马洁 National Key Laboratory for Remanufacturing Beijing 100072 ChinaSchool of Materials Science and Engineering Beijing Polytechnic University Beijing 100022 China National Key Laboratory for Remanufacturing Beijing 100072 China National Key Laboratory for Remanufacturing Beijing 100072 ChinaMetrology Center of Aviation Equipments Beijing 100070 China School of Materials Science and Engineering Beijing Polytechnic University Beijing 100022 China Department of Chemistry Capital Normal University Beijing 100037 China

Based on the advanced integrated technology of materials preparation and formation, a new pattern Zn-Al-Mg-RE anti-corrosion coating for steel structure sustainable design was manufactured by cored wires and high velocity arc spraying (HVAS) technologies. The developments of thermally sprayed coatings for steel structure protection were described. Based on Al, Zn, Zn-Al and Zn-Al-Mg coatings, the anti-corrosion properties of new-pattern Zn-Al-Mg-RE coating were evaluated through electrochemical methods including electrochemical polarization and electrochemical impedance spectroscopy (EIS) coupled with SEM and XRD. The models of Zn-Al-Mg-RE coating undergoing corrosion with the initial pinhole defect and the latter with accelerated products were also discussed. The results show that Zn-Al-Mg-RE coating exhibites excellent corrosion resistance for long-term immersion, which is helpful for the sustainable design of steel structure in aggressive corrosion conditions. And the corrosion products seem to possess certain self-sealing function.

关键词： integration of materials preparation and formation Zn-Al-Mg-RE coating sustainable design cored wires high velocity arc spraying

Core competencies and perceived training needs of nurses in the background of Internet plus nursing service:a qualitative descriptive study

在线全文

学校读者我要写书评

暂无评论

Frontiers of Nursing 2024年第2期11卷 181-190页

作者： Qiang-Hui-Zi Zhang Wei-Wei Liu Zhen-Zhen Cheng School of Nursing Capital Medical UniversityBeijing 100069China Department of Orthopedics Peking University Shougang HospitalBeijing 100043China

Background:The Internet plus nursing service program is being piloted in China,which has become a new home nursing service model led by *** enable safe and effective homecare service delivery,nurses working in the program need a high level of ***,the content of these core competencies and the training needs of nurses for Internet plus nursing services are still ***:To describe nurses’perceptions of core competencies and training needs to work in the Internet plus nursing service program,thereby providing a reference for the development of training ***:A qualitative descriptive study using semi-structured interviews was conducted on 15 nurses with experience of working in the Internet plus nursing service *** were audio-recorded and transcribed verbatim,and the data were analyzed using thematic ***:Core competencies involved comprehensive assessment competence,direct care practice competence,health education and consulting competence,risk estimation and response competence,and communication *** needs involved complex operational items,knowledge of chronic disease management,professional communication,risk identification and response,nursing standards,norms,and procedures,and utilization of information ***:The training system may be developed based on nurses’core competencies and their training needs to promote professional development of the Internet plus nursing service.

关键词： core competence Internet plus nursing service nursing qualitative study training needs

Strict Neighbor-Distinguishing Total Index of Graphs

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2022年第4期38卷 770-776页

作者： Jing GU Wei Fan WANG Yi Qiao WANG Department of Mathematics Zhejiang Normal UniversityJinhua 321004P.R.China School of Management Beijing University of Chinese MedicineBeijing 100029P.R.China

A total-coloring of a graph G is strict neighbor-distinguishing if for any two adjacent vertices u and v,the set of colors used on u and its incident edges and the set of colors used on v and its incident edges are not included with each *** strict neighbor-distinguishing total indexχ"_(snd)(G)of G is the minimum number of colors in a strict neighbor-distinguishing total-coloring of *** this paper,we prove that every simple graph G withΔ(G)≥3 satisfiesχ"_(snd)(G)≤2Δ(G).

关键词： Strict neighbor-distinguishing total-coloring Strict neighbor-distinguishing total index Maximum degree

Global output feedback control of feedforward nonlinear time-delay systems with unknown growth rate and unknown measurement sensitivity

在线全文

学校读者我要写书评

暂无评论

Control Theory and Technology 2024年第1期22卷 122-134页

作者： Weiyong Yu Keao Gao Hongbing Zhou Qiang Liu Academy of Artificial Intelligence Beijing Institute of Petrochemical TechnologyBeijing102617China School of Mathematics and Statistics Nanyang Normal UniversityNanyang473061HenanChina

This paper discusses the problem of global state regulation via output feedback for a class of feedforward nonlinear time-delay systems with unknown measurement sensitivity. Different from previous works, the nonlinear terms are dominated by upper triangular linear unmeasured (delayed) states multiplied by unknown growth rate. The unknown growth rate is composed of an unknown constant, a power function of output, and an input function. Furthermore, due to the measurement uncertainty of the system output, it is more difficult to solve this problem. It is proved that the presented output feedback controller can globally regulate all states of the nonlinear systems using the dynamic gain scaling technique and choosing the appropriate Lyapunov–Krasovskii functionals.

关键词： Adaptive control Dynamic gain controllers Feedforward time-delay systems Measurement sensitivity Output feedback

THE PERSISTENCE OF SOLUTIONS IN A NONLOCAL PREDATOR-PREY SYSTEM WITH A SHIFTING HABITAT

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2024年第3期44卷 1096-1114页

作者：赵敏袁荣 School of Science Tianjin Chengjian UniversityTianjin300384China Laboratory of Mathematics and Complex Systems(Ministry of Education) School of Mathematical SciencesBeijing Normal UniversityBeijing100875China

In this paper,we mainly study the propagation properties of a nonlocal dispersal predator-prey system in a shifting *** is known that Choi et al.[J Differ Equ,2021,302:807-853]studied the persistence or extinction of the prey and of the predator separately in various moving *** particular,they achieved a complete picture in the local diffusion ***,the question of the persistence of the prey and of the predator in some intermediate moving frames in the nonlocal diffusion case was left open in Choi et al.'s *** using some a prior estimates,the Arzelà-Ascoli theorem and a diagonal extraction process,we can extend and improve the main results of Choi et *** achieve a complete picture in the nonlocal diffusion case.

关键词： predator-prey system persistence nonlocal dispersal shifting environment