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Real-time reliability prediction for dynamic systems with both deteriorating and unreliable components

Science in china(Series F) 2009年第11期52卷 2234-2246页

作者： XU ZhengGuo1,2, JI YinDong2,3 & ZHOU DongHua1,2? 1 Department of automation, Tsinghua university, beijing 100084, china 2 Tsinghua National Laboratory for Information Science and technology, Tsinghua university, beijing 100084, china 3 Research Institute of Information technology (RIIT), Tsinghua university, beijing 100084, china Department of automation Tsinghua University Beijing 100084 China Tsinghua National Laboratory for Information Science and technology Tsinghua University Beijing 100084 China Research Institute of Information technology (RIIT) Tsinghua University Beijing 100084 China

As an important technology for predictive maintenance, failure prognosis has attracted more and more attentions in recent years. Real-time reliability prediction is one effective solution to failure prognosis. Considering a dynamic system that is composed of normal, deteriorating and unreliable components, this paper proposes an integrated approach to perform real-time reliability prediction for such a class of systems. For a deteriorating component, the degradation is modeled by a time-varying fault process which is a linear or approximately linear function of time. The behavior of an unreliable component is described by a random variable which has two possible values corresponding to the operating and malfunction conditions of this component. The whole proposed approach contains three algorithms. A modified interacting multiple model particle filter is adopted to estimate the dynamic system＇s state variables and the unmeasurable time-varying fault. An exponential smoothing algorithm named the Holt＇s method is used to predict the fault process. In the end, the system＇s reliability is predicted in real time by use of the Monte Carlo strategy. The proposed approach can effectively predict the impending failure of a dynamic system, which is verified by computer simulations based on a three-vessel water tank system.

关键词： reliability failure prognostics dynamic systems fault prediction particle filtering interacting multiple model exponential smoothing,predictive maintenance

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Boundedness for commutators of fractional Hardy operators on Herz spaces

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Progress in Natural Science:Materials International 2007年第1期17卷 20-25页

作者： FU Zunwei, LIU Zongguang and LU Shanzhen ( School of Mathematical Sciences, beijing Normal university, beijing 100875, china Department of Mathematics, Linyi Normal university, Linyi 276005, china Department of Mathematics, china university of Mining and technology, beijing 100083, china) [a]School of Mathematical Sciences Beijing Normal University Beijing China [b]Departhent of Mathematics Linyi Normal University Linyi China [c]Departhent of Mathematics China University of Mining and Technology Beijing China

Some boundedness results are established for commutators generated by classical fractional Hardy operators and one-sided CMO functions on the homogeneous Herz spaces, which extends some known results.

关键词： fractional Hardy operator Hardy’s integral inequality commutator one-sided CMO function homogeneous Herz space.

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Nonlinear Theory on Dynamic Controlling Interface Patterns DuringSolidification of a Dilute Binary Alloy

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 253-258页

作者： Zidong Wang Hanqi Hu(Material Science and Engineering School, university of Science and technology beijing, beijing 100083, china) Material Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

In non-equilibrium nonlinear region, the nonlinear equations of time dependence of perturbation amplitude at the solid/liquidinterface during solidification of a dilute binary alloy are established on the base of assuming that there is local equilibrium at the solid/liquid interface and considering that curvature, temperature and composition at the solid/liquid interface which are related to the perturbation amplitude are nonlinear. As a result, patterns at the solid/liquid interface during solidification process, which is from nonsteadystate to steady state can be controlled by these nonlinear equations.

关键词： nonlinearity solidification, dilute binary alloy, dynamic control

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A formal method to real-time protocol interoperability testing

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Science in china(Series F) 2008年第11期51卷 1723-1744页

作者： WANG ZhiLiang1,3,YIN Xia2,3 & JING ChuanMing2,3 1 Network Research Center,Tsinghua university,beijing 100084,china 2 Department of Computer Science and technology,Tsinghua university,beijing 100084,china 3 Tsinghua National Laboratory for Information Science and technology(TNList) ,beijing 100084,china 1. Network Research Center Tsinghua University Beijing 100084 China 3. Tsinghua National Laboratory for Information Science and technology (TNList) Beijing 100084 China 2. Department of Computer Science and technology Tsinghua University Beijing 100084 China

Interoperability testing is an important technique to ensure the quality of implementations of network communication protocol. In the next generation Internet protocol, real-time applications should be supported effectively. However, time constraints were not considered in the related studies of protocol interoperability testing, so existing interoperability testing methods are difficult to be applied in real-time protocol interoperability testing. In this paper, a formal method to real-time protocol interoperability testing is proposed. Firstly, a formal model CMpTIOA （communicating multi-port timed input output automata） is defined to specify the system under test （SUT） in real-time protocol interoperability testing; based on this model, timed interoperability relation is then defined. In order to check this relation, a test generation method is presented to generate a parameterized test behavior tree from SUT model; a mechanism of executability pre-determination is also integrated in the test generation method to alleviate state space explosion problem to some extent. The proposed theory and method are then applied in interoperability testing of IPv6 neighbor discovery protocol to show the feasibility of this method.

关键词： protocol testing interoperability testing real-time testing test generation timed input output automata(TIOA)

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Rate Equation of Small Particle-Air Bubble Attachment in Turbulent Flow of Flotation Cells

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 185-191页

作者： Shouci Lu Jingyong Guo(Resources Engineering School, university of Science and technology beijing, beijing 1 00083, china) Resources Engineering School University of Science and Technology Beijing Beijing 100083 China

A rate equation of small particle-air bubble attachment in the turbulent now of flotation cells has beenderived. The equation, integrating both the collision probability and adhesion probability together, represents theprobability of attachment between particle and bubble in the turbulent flow. 'Capture efficiency' f(a) is introducedinto the rate equation to reflect the influence of energy hairier on the attachment rate. Three typical situations of particle-bubble interaction in flotation process have been discussed. For a completely hydrophobic particle-bubble system,f(a) = 1. This means that all collision leads to attachment. Whereas for hydrophilic particle-bubble systems, .f(a) =0. Thus no adhesion of particle on bubble occurs at all. In real notation circumstances, however, there always existsa certain energy barrier between the particle and the bubble. Therefore, f(a) = 0～1. In such cases, not all collisionsresult in particle-bubble attachment.

关键词： rate equation turbulent flow flotation cell capture efficiency

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Flotation Separating Rutile from Calcium and Silicon Gangue Minerals

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Rare Metals 2001年第4期20卷 205-208页

作者： Hao Ding1, HaiLin 2 1) beijing Academy of Building Materials, beijing 100041, china 2) university of Science and technology beijing, beijing 100083, china beijing Acad Bldg Mat Beijing 100041 Peoples R China Univ Sci & Technol beijing Beijing 100083 Peoples R China

Rutile separation from calcite, apatite and quartz by flotation was investigated. The results show that the rutile separation from calcium and silicon gangue minerals can be realized with alkyl-imino-bismethylene phos... 详细信息

关键词： rutile calcium and silicon gangue minerals flotation separate alkyl-imino-bismethylene phosphoric acid sodium hexametaphosphate

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Theory for Constructing Generalized Synchronization and Applications

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International Journal of Minerals,Metallurgy and Materials 2000年第3期14卷 225-228页

作者： Xiaodan Zhang, Lequan Min (Applied Science School, university of Science and technology beijing, beijing 100083, china) Applied Science School University of Science and Technology Beijing Beijing 100083 China

The approaches for constructing directionally coupled generalized synchronization (GS) systems are presented, which are available for the driving system and the respond system that are in GS via a given diffeomorphi... 详细信息

关键词： Chaos generalized synchronization predictability

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High Temperature Ductility Loss of 16MnCr5 Pinion Steels

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International Journal of Minerals,Metallurgy and Materials 1998年第3期12卷 123-128页

作者： Haiwen Luo Pei Zhao Zijiu Dang(Metallurgy School, university of Science and technology beijing, beijing 100083, china) Metallurgy School University of Science and Technology Beijing Beijing 100083 China

A wide ductility trough covering from 700 to 1100 is observed in the curve of Reduction of Area (RA) *** for 16MnCr5 pinion steel. At 750℃, corresponding to the minimum of RA, it is grain boundary slidingthat controls its hot ductility rather than usual Deforming Induced Ferrite (DIF), which can only appear just below750℃ and slightly improve hot ductility. The volume fraction of ferrite is dependent on the strain and strain *** a critical strain must be necessary for formation of DIF then with strain rate increasing, the volume fractionof DIF decreases but RA is elevated. In the γ phase region, hot ductility is seriously deteriorated because of grainboundary sliding promoted by oxidcs and sulfides at the grain boundary and recovered because of dynamic recrystal-lization at higher temperature; when strain rate increases, ductility is improved as there is insufficient time for cracksto propagate along the γ grain boundary as well as dynamically precipitating, and ductility trough becomes narrowerbecause the temperature for onset of dynamic recrystallization decreases. In addition, γ→α phase transformationintroduced by temperature drop before the tensile test encourages precipitation of AlN and impairs ductility.

关键词： hot ductility deforming induced ferrite grain boundary sliding precipitates

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Environmental benefits of underground coal gasification

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Journal of Environmental Sciences 2002年第2期14卷 284-288页

作者： LIU Shu qin, LIU Jun hua, YU LI (china university of Mining & technology, beijing 100083, china. china university of Mining & technology Beijing 100083 Chin

Environmental benefits of underground coal gasification are evaluated. The results showed that through underground coal gasification, gangue discharge is eliminated, sulfur emission is reduced, and the amount of ash, mercury, and tar discharge are decreased. Moreover, effect of underground gasification on underground water is analyzed and CO 2 disposal method is put forward.

关键词： environmental benefits coal underground coal gasification

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REACTION MODEL IN Al-Ti-C SYSTEM

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Acta Metallurgica Sinica(English Letters) 1995年第2期8卷 137-140页

作者： WANG Zidong HU Hanqi(university of Science and technology beijing.beijing,china)Li Qingchun(Harbin institute of technology,Harbin.china Univ of Science and technology Beijing China

In this Paper,interaction coefficients among Al,Ti and C in Al-Ti-C ternary system and actual free energy of Al_3Ti,TiC and Al_4C_3,were calcutated via ternary alloy thermodynamic *** rsults show that,at low temperatures,Al_3Ti forms through the reaction of aluminium with titanium,and at high temperatures,the TiC forms hy the reaction of carbon with Al_*** reaction mechanism was verified by the experimental results.

关键词： thermodynamics reaction mechanism Al-Ti-C.system

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