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Chinese Journal of Aeronautics 2019年第3期32卷 627-638页

作者： Diyin TANG Jinrong CAO Jinsong YU School of Automation Science and Electrical Engineering Beihang University Collaborative Innovation Center of Advanced Aero-Engine

For critical engineering systems such as aircraft and aerospace vehicles, accurate Remaining Useful Life(RUL) prediction not only means cost saving, but more importantly, is of great significance in ensuring system reliability and preventing disaster. RUL is affected not only by a system's intrinsic deterioration, but also by the operational conditions under which the system is operating. This paper proposes an RUL prediction approach to estimate the mean RUL of a continuously degrading system under dynamic operational conditions and subjected to condition monitoring at short equi-distant intervals. The dynamic nature of the operational conditions is described by a discrete-time Markov chain, and their influences on the degradation signal are quantified by degradation rates and signal jumps in the degradation model. The uniqueness of our proposed approach is formulating the RUL prediction problem in a semi-Markov decision process framework, by which the system mean RUL can be obtained through the solution to a limited number of equations. To extend the use of our proposed approach in real applications, different failure standards according to different operational conditions are also considered. The application and effectiveness of this approach are illustrated by a turbofan engine dataset and a comparison with existing results for the same dataset.

关键词： Condition-specific failure threshold Degradation modeling Dynamic operational conditions Remaining useful life Semi-Markov decision process

A continuous-time formulation for refinery production scheduling problems involving operational transitions in mode switching

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Chinese Journal of Chemical Engineering 2016年第8期24卷 1020-1031页

作者： Lei Shi Yongheng Jiang Ling Wang Dexian Huang Institute of Process Control Engineering Department of Automation Tsinghua University Tsinghua National Laboratory for Information Science and Technology Tsinghua University

In the refinery scheduling, operational transitions in mode switching are of great significance to formulate dynamic nature of production and obtain efficient schedules. The discrete-time formulation meets two main challenges in modeling: discrete approximation of time and large size of mixed-integer linear problem(MILP).In this article, a continuous-time refinery scheduling model, which involves transitions of mode switching, is presented due to these challenges. To reduce the difficulty in solving large scale MILPs resulting from the sequencing constraints, the global event-based formulation is chosen. Both transition constraints and production transitions are introduced and the numbers of key variables and constraints in both of the discrete-time and continuous-time formulations are analyzed and compared. Three cases with different lengths of time horizons and different numbers of orders are studied to show the efficiency of the proposed model.

关键词： Refinery scheduling operational transitions Continuous-time representation

A Jacobi Spectral Collocation Scheme Based on operational Matrix for Time-fractional Modified Korteweg-de Vries Equations

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Computer Modeling in Engineering & Sciences 2015年第3期104卷 185-209页

作者： A.H.Bhrawy E.H.Doha S.S.Ezz-Eldien M.A.Abdelkawy Department of Mathematics Faculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia Department of Mathematics Faculty of ScienceBeni-Suef UniversityBeni-SuefEgypt Department of Mathematics Faculty of ScienceCairo UniversityGizaEgypt Department of Mathematics Faculty of ScienceAssiut UniversityNew Valley BranchEl-Kharja 72511Egypt

In this paper,a high accurate numerical approach is investigated for solving the time-fractional linear and nonlinear Korteweg-de Vries(KdV)*** equations are the most appropriate and desirable definition for physical *** spectral collocation method and the operational matrix of fractional derivatives are used together with the help of the Gauss-quadrature formula in order to reduce such problem into a problem consists of solving a system of algebraic equations which greatly simplifying the *** approach is based on the shifted Jacobi polynomials and the fractional derivative is described in the sense of *** addition,the presented approach is applied also to solve the timefractional modified KdV *** testing the accuracy,validity and applicability of the developed numerical approach,we apply it to provide high accurate approximate solutions for four test problems.

关键词： KdV equation Jacobi polynomials operational matrix Gauss quadrature Collocation spectral method Caputo derivative

Validation of an operational forecasting system of sea dike risk in the southern Zhejiang Province, South China

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Journal of Oceanology and Limnology 2019年第6期37卷 1929-1940页

作者： LI Tao WANG Fangdong HOU Jingming CHE Zhumei DONG Jianxi National Marine Environmental Forecasting Center Beijing 100081China Key Laboratory of Research on Marine Hazards Forecasting of State Oceanic Administration Beijing 100081China Beijing Space Flight Control Center Beijing 100094China Marine Monitoring and Forecasting Center of Zhejiang Province Hangzhou 310007China

In this study,an operational forecasting system of sea dike risk in the southern Zhejiang Province,South China was developed based on a coupled storm-surge and wave *** forecasting system is important because of the high cost of storm-surge damage and the need for rapid emergency planning.A comparison with astronomical tides in 2016 and the validation of storm surges and high water marks of 20 typhoons verified that the forecast system has a good simulation *** system can forecast relatively realistic water levels and wave heights as shown under the parametric atmospheric forces simulated in a case study;the sea dikes in credible high risk were mainly located in the estuaries,rivers,and around the islands in the southern ***,the forecast system is applicable in the southern Zhejiang with a support to the effective prevention from typhoon storm-surge damage.

关键词： storm surge sea dike operational forecast southern Zhejiang Province risk calculation

Synergy methodology for multi-objective operational control of reservoirs in Yellow River basin

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Science China(Technological Sciences) 2004年第z1期47卷 212-223页

作者： HUANG Qiang CHANG Jianxia WANG Yimin PENG Shaoming Hydraulic and Hydrauelectric Institute Xi'an University of Technology Xi'an 710048 China Hydraulic and Hydrauelectric Institute Xi'an University of Technology Xi'an 710048 China Hydraulic and Hydrauelectric Institute Xi'an University of Technology Xi'an 710048 China Hydraulic and Hydrauelectric Institute Xi'an University of Technology Xi'an 710048 China

This paper presents an application of synergy methodology to a multi- objective operational control of reservoirs. This methodology enables a comprehensive consideration of multi-objectives which may be conflicting and non commensurate such as municipal and industrial water supply, flood protection, and hydroelectric power generation etc. On the basis of the synergy theory, a harmony degree model of sub- system was established to describe the coordination magnitude. Combined with information entropy, a harmony degree entropy was proposed to determine the water resources evolvement direction. While implementing the control, an initial scheme for reservoir operation was obtained from simulation first, then control was carried out according to the harmony degree and harmony degree entropy by applying synergy theory. The application of the methodology to reservoir system in the Yellow River was reported in this paper through a case study.

关键词： reservoir system, operational control, synergy theory, harmony degree, harmony degree entropy.

operational concepts of HVDC in the context of security assessment in the German transmission grid

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Global Energy Interconnection 2019年第2期2卷 130-132页

作者： Annika Klettke Marius Sieberichs Albert Moser Institute of Power Systems and Power Economics

Because of the realization of HVDC connections parallel to the synchronous grid in Germany, operational concepts become more important in the context of system security aspects. In this article commonly known concepts are analyzed regarding their suitability for the German transmission system. Therefore, an approach for the analysis was developed and exemplary results are given using this approach. Under consideration of the overall system, the concepts of reducing losses in combination with minimizing(n-1)-warnings or-indications^1 as well as the sole minimization of(n-1)-warnings and-indications are the most reasonable approaches. However, under grid security aspects best results can be achieved by reducing operational limits and therefore, by the minimization of(n-1)-warnings.

关键词： System security Transmission grid operational concept HVDC

CASE STUDY OF THE operational ENERGY CONSUMPTION AND CARBON EMISSIONS FROM A BUILDING IN NANJING BASED ON A SYSTEM DYNAMICS APPROACH

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Journal of Green Building 2016年第3期11卷 126-142页

作者： Changhai Peng Jianqiang Yang Jinfu Huang School of Architecture Southeast UniversityNanjing 210096PR China Key Laboratory of Urban and Architectural Heritage Conservation(Southeast University) Ministry of EducationPR China College of Engineering and Applied Science University of Colorado DenverDenverCO 80217USA

Buildings are responsible for more than forty percent of global energy consump-tion and as much as one third of global greenhouse gas ***,the energy conservation and exhaust reduction of a building can be easily understood by accurately calculating a building’s carbon emissions during its operational *** the present study,a system dynamics(SD)approach to calculate the energy consumption and carbon emissions from a building during its operational stage is quantitatively developed through a case study on an office building in *** obtained results demonstrate that:a)the difference between the results of SD and that of EnergyPlus is so small that a SD approach is acceptable;b)the variation between the real monitored data and that of simulation by SD and EnergyPlus is reasonable;c)the physical meanings of the variables in the SD model are clear;d)the parameters of the SD model and the relationships between the variables can be determined by a qualitative-and-quantitative combined analysis.

关键词： operational energy consumption carbon emissions buildings system dynamics approach

operational CHARACTERISTICS AND IMPROVEMENTS OF THE SHANGHAI 4UH PELLETRON

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Nuclear Science and Techniques 1991年第4期2卷 250-252页

作者：顾瀚袁伦明毛羽徐明娟

This paper summarizes performance data and operational experiences gained with 4UH Pelletron.

关键词： Pelletron operational characteristics Accelerator troubles Gas feed facility

Development of operational Space Weather Prediction Models

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空间科学学报 2014年第5期34卷 688-702页

作者： GONG Jiancun LIU Siqing SHI Liqin LUO Bingxian CHEN Yanhong HUANG Wengeng CAO Jinbin XIE Lun LEI Jiuhou TANG Weiwei Center for Space Science and Applied Research Chinese Academy of Sciences Space Science Institute School of Astronautics Beihang University School of Earth and Space Science Peking University School of Earth and Space Sciences University of Science and Technology of China

In this report, we summarize the needs of space weather models, and recommend that developing operational prediction models, rather than transitioning from research to operation, is a more feasible and critical way for space weather services in the near future. operational models for solar wind speed, geomagnetic indices, magnetopause, plasma sheet energetic electrons, inner boundary of ion plasma sheet, energetic electrons in outer radiation belt, and thermospheric density at low Earth orbit, have been developed and will be introduced briefly here. Their applications made a big progress in space weather services during the past two years in China.

关键词： operational model Space weather prediction

Recent advances in operational tropical cyclone genesis forecast

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Tropical Cyclone Research and Review 2023年第4期12卷 323-340页

作者： K.K.Hon Robert Ballard Eric Blake Steph Bond Robb Gile Daniel Halperin Charles Helms Hoang Lam Xinyan Lyu Mrutyunjay Mohapatra Monica Sharma Akira Shimokobe Ralf Toumi Seonghee Won Hong Kong Observatory Hong KongChina Regional Specialized Meteorological Center Honolulu HonoluluUSA National Hurricane Center Miami FLUSA Bureau of Meteorology MelbourneAustralia Philippine Atmospheric Geophysicaland Astronomical Services AdministrationDepartment of Science and TechnologyQuezon CityPhilippines Embry-Riddle Aeronautical University USA National Aeronautics and Space Administration MarylandUSA Vietnam Meteorological and Hydrological Administration HanoiViet Nam China Meteorological Administration BeijingChina Regional Specialized Meteorological Center New Delhi New DelhiIndia Regional Specialized Meteorological Center Tokyo-Typhoon Centre TokyoJapan Department of Physics Imperial College LondonUK Korea Meteorological Administration SeoulRepublic of Korea

Tropical cyclone(TC)genesis prediction is a major scientific challenge to the TC operation and research *** report surveys the current status of TC genesis forecasts by a number of major operational centers covering the key ocean basins across both *** IWTC-9,we see an emergence of probabilistic TC genesis forecast products by operational centers,typically supported by the statistical processing of a combination of ensemble prediction and satellite analysis,covering time periods of couple of days to weeks *** prevalence of multi-center grand ensemble approach highlights the uncertainties involved and the forecast challenges in quantitative genesis *** operational practice might differ across agencies,verification efforts generally report a steady or slightly improving skill level in terms of reliability,which likely results from the continual improvement in global numerical weather prediction capability.

关键词： Cyclogenesis Tropical cyclone genesis Ensemble Prediction operational Forecasting Probabilistic Verification Survey Global