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

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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

Regulations and Practice on Flue Gas Denitrification for Coal-Fired Power Plants in china

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Electricity 2008年第1期19卷 49-52页

作者： Zhu Fahua1 and Zhao Guohua2.1. state Power environmental {2. Research Institute 2. Nanjing University of Information Science & Technology state Power environmental {2. Research Institute Nanjing University of Information Science & Technology

In china, according to the relative up-to-date regulations and standards, the maincontrol measure for NOX emission of coal-fired power plants is, in principle, low NOXcombustion. However, in recent years, more and more newlyapproved coal-fired plantswere required to install flue gas denitrification equipment. This article expounds if fluegas denitrification is necessary from several aspects, including constitution of NOX, itsimpact to environment, operation ofdeNOXequipment in USA, as wellas the differencein ambient air quality standard between china and World Health Organization. It setsforth themes in urgent need of study and areas where deNOX equipment is necessaryfor new projects, besides a recommendation that the emission standards for thermalpowerplants should be revised as soon as possible in china.

关键词： Regulations and Practice on Flue Gas Denitrification for Coal-Fired Power Plants in china

Slope Reinforcement for Housing in Three Gorges Reservoir Area

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Journal of Mountain Science 2011年第2期8卷 314-320页

作者： WU Faquan LUO Yuanhua CHANG Zhonghua Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Office of Three Gorges Project Construction Committee the State Council of China Beijing 100038 China

The Three Gorges Project of the Yangtze River is the largest hydropower-complex project under construction in the world. Under the largescale relocation projects, 2.74 engineered slopes are formed along with the construction of new towns. In this paper, the cutting slopes are mainly soil slopes and rock slopes. Soil slopes include residual soil slopes, colluvial accumulation slopes, swelling soil slopes, and artificial earth fill slopes, etc. Rock slopes include blocky structure rock slopes, layer structure rock slopes, and clastic structure rock slopes, etc. Varied protection measures have been used for slope protection in the reservoir area including shotcrete concrete-anchor bars, frame beams, retaining walls, slope stabilizing piles, sheet-pile walls, anchorage anti-shear tunnels, flexible protection grids, and drainage, etc. Besides, slope deformation monitoring systems have been set up to monitor deformation failure and the stability state of slopes. The protection measures have guaranteed slope safety and maintained a harmony with the urban environment and surrounding landscape.

关键词： Slope reinforcement Housing for resettlement Three Gorges Reservoir

Mechanism for calcite dissolution and its contribution to development of reservoir porosity and permeability in the Kela 2.gas field,Tarim Basin,china

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Science china Earth Sciences 2008年第4期51卷 567-578页

作者： YU BingSong1,3, DONG HailLiang2.3 & RUAN Zhuang1,3 1 state Key Laboratory of Geological processes and Mineral Resources, {2. University of Geosciences, beijing 100083, {2. 2.Department of Geology, Miami University,Oxford, OH 45056, USA 3 Geomicrobiology Laboratory, {2. University of Geosciences, beijing, 100083, {2. state Key Laboratory of Geological processes and Mineral Resources China University of Geosciences Beijing 100083 China Department of Geology Miami University Oxford OH 45056 USA Geomicrobiology Laboratory China University of Geoscien

This study is undertaken to understand how calcite precipitation and dissolution contributes to depth-related changes in porosity and permeability of gas-bearing sandstone reservoirs in the Kela 2.gas field of the Tarim Basin, Northwestern china. Sandstone samples and pore water samples are col-lected from well KL2.1 in the Tarim Basin. Vertical profiles of porosity, permeability, pore water chem-istry, and the relative volume abundance of calcite/dolomite are constructed from 3600 to 4000 m below the ground surface within major oil and gas reservoir rocks. Porosity and permeability values are in-versely correlated with the calcite abundance, indicating that calcite dissolution and precipitation may be controlling porosity and permeability of the reservoir rocks. Pore water chemistry exhibits a sys-tematic variation from the Na2.O4 type at the shallow depth (3600-3630 m), to the NaHCO3 type at the intermediate depth (3630―3695 m),and to the CaCl2.type at the greater depth (372.―3938 m). The geochemical factors that control the calcite solubility include pH, temperature, pressure, Ca2. concen-tration, the total inorganic carbon concentration (ΣCO2., and the type of pore water. Thermodynamic phase equilibrium and mass conservation laws are applied to calculate the calcite saturation state as a {2. of a few key parameters. The model calculation illustrates that the calcite solubility is strongly dependent on the chemical composition of pore water, mainly the concentration difference between the total dissolved inorganic carbon and dissolved calcium concentration (i.e., [ΣCO2. -[Ca2.]). In the Na2.O4 water at the shallow depth, this index is close to 0, pore water is near the calcite solubility. Calcite does not dissolve or precipitate in significant quantities. In the NaHCO3 water at the intermedi-ate depth, this index is greater than 0, and pore water is supersaturated with respect to calcite. Massive calcite precipitation was observed at this depth interval and

关键词： calcite dissolution porosity thermodynamic Tarim Basin

On (2.m + 1)-variable symmetric Boolean functions with submaximum algebraic immunity 2.(m-1)

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Science china Mathematics 2009年第1期52卷 17-28页

作者： LIAO QunYing1, LIU Feng2.& FENG KeQin2.1 College of Mathematics and Software Sciences, Sichuan Normal University, Chengdu 610066, china 2.Department of Mathematical Sciences, Tsinghua University, beijing 100084, china College of Mathematics and Software Sciences Sichuan Normal University Chengdu 610066 China Department of Mathematical Sciences Tsinghua University Beijing 100084 China

All (2. +1)-variable symmetric Boolean functions with submaximal algebraic immunity 2.-1 are described and constructed. The total number of such Boolean functions is 32.·2.m-3 +3m-2.· 2. - 2.for m≥2.

关键词： symmetric Boolean function algebraic immunity cryptography

Heterogeneous reaction of formaldehyde on the surface of TiO_2.particles

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Science china Chemistry 2010年第12期53卷 2644-2651页

作者： XU BingYe 1,2.ZHU Tong 1,TANG XiaoYan 1 & SHANG Jing 1 1 state Key Joint Laboratory of environmental Simulation and Pollution Control College of environmental Sciences and Engineering,Peking University,beijing 100871,china 2.Zhejiang Province environmental Monitoring Center,Hangzhou 310012.china 1. state Key Joint Laboratory of environmental Simulation and Pollution Control College of environmental Sciences and Engineering Peking University Beijing 100871 China2. Zhejiang Province Environmental Monitoring Center Hangzhou 310012 China

The heterogeneous reaction of formaldehyde (HCHO) on the surface of titanium dioxide (TiO2. was investigated in situ using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with ion chromatography (IC),X-ray diffraction (XRD),and transmission electron microscopy (TEM).Formate,dioxymethylene,methoxy,and polyoxymethylene were observed in the infrared spectra of TiO2.particles during the *** the surface of TiO2.the adsorbed HCHO was first oxidized to dioxymethylene and further oxidized to *** effects of temperature and ultraviolet radiation (UV) on the reaction products and reactive uptake coefficients were studied,and the results indicate that the reaction rate can be accelerated at increasing temperatures as well as under *** heterogeneous reaction mechanisms of HCHO on the surface of TiO2.in the dark and under UV irradiation are *** measurements show that formate formation on TiO2.is second order in HCHO concentration and the initial reactive uptake coefficients at room temperature calculated with the Brunauer-EmmettTeller specific surface area are (0.5-5) × 10-8 ([HCHO]:1 × 1013-2.× 10 14 molecules/cm3).A linear function relationship exists between the uptake coefficient and the *** apparent activation energy of the reaction was also determined.

关键词： DRIFTS formaldehyde heterogeneous reaction reactive uptake coefficient TiO2

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固体火箭冲压发动机燃烧室热防护层烧蚀计算

推进技术 2002年第5期23卷 375-378页

作者：孙冰刘小勇林小树蔡国飙北京航空航天大学宇航学院北京100083 航天科工集团公司所北京100074

为了研究冲压发动机燃烧室的热防护性能,用类比法计算了整体式固体火箭冲压发动机燃烧室壁面的烧蚀,其中考虑了热解气流对烧蚀的影响,并将国外有关固体火箭发动机喷管烧蚀计算时所用经验参数(指前因子)通过换算转换到冲压发动机燃烧室... 详细信息

为了研究冲压发动机燃烧室的热防护性能,用类比法计算了整体式固体火箭冲压发动机燃烧室壁面的烧蚀,其中考虑了热解气流对烧蚀的影响,并将国外有关固体火箭发动机喷管烧蚀计算时所用经验参数(指前因子)通过换算转换到冲压发动机燃烧室烧蚀计算中。计算结果符合物理规律,并与试验结果符合较好。该项研究为冲压发动机燃烧室热防护层的设计提供了有效的分析手段。

关键词：固体火箭冲压发动机燃烧室热防护层烧蚀计算

Damage and progressive failure of concrete structures using non-local peridynamic modeling

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Science china(Technological Sciences) 2011年第3期54卷 591-596页

作者： HUANG Dan1,2. ZHANG Qing1,2.& QIAO PiZhong1,3 1 state Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 2.0098, china 2.Department of Engineering Mechanics, Hohai University, Nanjing 2.0098, china 3 Department of Civil and environmental Engineering, Washington state University, Pullman, WA 99164-2.10, USA 1. state Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China2. Department of Engineering Mechanics Hohai University Nanjing 210098 China3. Department of Civil and Environmental Engineering Washington State University Pullman WA 99164-2910 USA

Peridynamics (PD), a recently developed theory of solid mechanics, which employs a non-local model of force interaction and makes use of integral formulation rather than the spatial partial differential equations used in the classical continuum mechanics theory, has shown effectiveness and promise in solving discontinuous problems at both macro and micro scales. In this paper, the peridynamics theory is used to analyze damage and progressive failure of concrete structures. A non-local peridynamic model for a rectangular concrete plate is developed, and a central pairwise force function is introduced to describe the interior interactions between particles within some definite distance. Damage initiation, evolution and crack propagation in the concrete model subject to in-plane uni-axial tension, in-plane uni-axial compression and out-of-plane impact load are investigated respectively. The numerical results show that discontinuities appear and grow spontaneously as part of the solution to the peridynamic equations of motion, and no special failure criteria or re-meshing techniques are required, which proves the potential of peridynamic modeling as a promising technique for analyzing the progressive failure of concrete materials and structures.

关键词： concrete damage progressive failure peridynamic model discontinuities

Analysis of the Effects of Slope Geometry on the Dynamic Response of a Near-field Mountain from the Wenchuan Earthquake

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Journal of Mountain Science 2010年第4期7卷 353-360页

作者： XIAO Shiguo FENG Wenkai ZHANG Jianjing Department of Geoteehnical Engineering Southwest Jiaotong University Chengdu 610031 China state Key Laboratory of Geohazard Prevention and Geoenvironment {2. Chengdu University of Technology Chengdu 610059 China Department of C-eoteehnical Engineering Southwest Jiaotong University Chengdu 610031 China

Fourier spectra and acceleration response spectra of near-field acceleration records of the 2.08 Wenchuan Earthquake have been *** fundamental frequencies(or predominant periods) were ***,the natural frequencies of a range of slopes with different geometric characteristics,such as height,slope ratio,and pattern,were *** seismic responses of the slopes were compared,and the variability of seismic response with the above geometric elements was *** show that if slope height increases,and provided that other conditions are unchanged,the natural frequency of the first mode of a doublesurface slope will change as a power ***,natural frequencies will diminish(based on a parabolic function) as the slope angle becomes *** the surface pattern and the number of surfaces on a slope can have a great impact on the seismic response of the ***,within a certain range of slope heights or angles,either height or angle will also greatly influence the variability of the seismic *** results of this research will be helpful to understanding seismic dynamic response features and explaining the ways that slope stability can be affected by earthquakes.

关键词： Wenchuan Earthquake Slope Geometric features Dynamic response Naturalfrequency