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Quenched moderate deviations principle for random walk in random environment

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Science china Mathematics 2010年第8期53卷 1947-1956页

作者： HONG WenMing 1 & WANG HuaMing 1,2 1 Key Laboratory of Mathematics and Complex Systems of Ministry of Education & School of Mathematical Sciences,beijing Normal university,beijing 100875,china 2 department of basic courses,Business College,beijing union university,beijing 100025,china Key Laboratory of Mathematics and Complex Systems of Ministry of Education & School of Mathematical Sciences Beijing Normal University Beijing China department of basic courses Business College Beijing Union University Beijing China

We derive a quenched moderate deviations principle for the one-dimensional nearest random walk in random environment,where the environment is assumed to be stationary and *** approach is based on hitting time decompos... 详细信息

关键词： random walk in random environment moderate deviations principle hitting time

A heuristic path-estimating algorithm for large-scale real-time traffic information calculating

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Science china(Technological Sciences) 2008年第S1期51卷 165-174页

作者： L WeiFeng1,ZHU TongYu1,WU DongDong2,DAI Hong3 & HUANG Jian1 1 State Key Laboratory for Software Development Environment,Beihang university,beijing 100083,china 2 beijing Transportation Information Center,beijing 100055,china 3 College of Arts & Science,beijing union university,beijing 100083,china State Key Laboratory for Software Development Environment Beihang University Beijing China beijing Transportation Information Center Beijing China College of Arts & Science Beijing Union University Beijing China

As the original Global Position System (GPS) data in Floating Car Data have the accuracy problem,this paper proposes a heuristic path-estimating algorithm for large-scale real-time traffic information calculating. It uses the heuristic search method,imports the restriction with geometric operation,and makes comparison between the vectors composed of the vehicular GPS points and the special road network model to search the set of vehicular traveling route candidates. Finally,it chooses the most optimal one according to weight. Experimental results indicate that the algorithm has considerable efficiency in accuracy (over 92.7%) and com-putational speed (max 8000 GPS records per second) when handling the GPS tracking data whose sampling rate is larger than 1 min even under complex road network conditions.

关键词： path-estimating floating car data (FCD) road network vector GPS

Valency Study of Vanadium in Stone Coal Ash of Jiangxi Province

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Journal of Earth Science 1990年第1期9卷 126-134页

作者： Xu Guozhen Ge Naie Li Jiguidepartment of basic courses, china university of Geosciences, beijing 100083

Vanadium-bearing stone coal is a new vanadium resource; recovery of V2O5 from the coal has been investigated. It has been found that a satisfactory extraction of V2O5 depends on both the oxidation of V and its reaction with sodium salt. V in the coal ash of Yushan mainly exists in two oxidation states; 98% V (Ⅲ) and 2% V(Ⅳ). The distribution of valency of V shows that organic matter determines V valency at low temperatures, at about 470℃ , V(Ⅲ) is completely oxidized to V (Ⅳ); above 500 ℃, the temperature is the most important factor for the oxidation of V At higher temperatures no more V is oxidized to V(Ⅴ); an equilibrium is established after 92% of V is oxidized to V(Ⅴ). The roles of NaCl in the recovery of V2O5 from the coal ash were discussed. The best conditions for roasting are temperature 750-800℃ for 1 h. under the oxidation-chlorination atmosphere. When the ore : NaCl = 100 :10 by weight, ηroast reaches 85.5%. According to the results, a flowsheet for V2O5 extraction from coal ash has been proposed.

关键词： coal ash NaCl / oxidation roasting leaching and extraction the soluble vanadate recovery Jiangxi Province.

Reverse reconciliation for continuous variable quantum key distribution

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Science china(Physics,Mechanics & Astronomy) 2010年第1期53卷 100-105页

作者： LU ZhiXin 1,2 , YU Li 1,2 , LI Kang 1,2 , LIU BingCan 1,2,3 , LIN JianGui 1,2 , JIAO RongZhen 1,2 & YANG BoJun 1,21 School of Science, beijing university of Posts and Telecommunications, beijing 100876, china 2 Key Laboratory of Information Photonics and Optical Communication, Ministry of Education, beijing university of Posts and Telecommunications, beijing 100876, china 3 department of Fundamental courses, Academy of Armored Force Engineering, beijing 100072, china School of Science Beijing University of Posts and Telecommunications Beijing China Key Laboratory of Information Photonics and Optical Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing China department of Fundamental courses Academy of Armored Force Engineering Beijing China

An efficient and practical post-processing technique based on reverse reconciliation for continuous variable quantum key distribution is proposed and simulated with low-density parity check (LDPC) codes. MultiLevel Coding/ MultiStage Decoding, which fully utilizes optimization technique such as vector quantization and iterative decoding and the optimal channel coding most close to the Shannon limit, was used to realize efficient reverse reconciliation algorithm. Simulation results showed that the proposed method can improve the secure key distribution rate to 2.2 kb/s and the coding efficiency to 0.89 over 20 km in single-mode optical fiber. Moreover, there still is room for much improvement.

关键词： quantum communication key distribution reverses reconciliation low-density parity check codes

Sensing characterization of Sn/In/Ti nanocomplex oxides for CO, CH_4 and NO_2

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Science china(Technological Sciences) 2007年第1期50卷 18-26页

作者： BAI ShouLi1, TONG ZhangFa2, LI DianQing1, HUANG XiaoWei3, LUO RuiXian1 & CHEN AiFan1 1 State Key Laboratory of Chemical Resource Engineering, beijing university of Chemical Technology, beijing 100029, china 2 School of Chemistry and Chemical Engineering, Guangxi university, Nanning 530004, china 3 College of Biochemical Engineering, beijing union university, beijing 100023, china State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing China School of Chemistry and Chemical Engineering Guangxi University Nanning China College of Biochemical Engineering Beijing Union University Beijing China

The nanocomplex oxides of Sn-In and Sn-In-Ti were prepared by controlled co-precipitation method as sensing materials of semiconductor gas sensors for detection of CO, CH4 and NO2. Through manipulating the Sn/In cation ratio, metal salt total concentration, precipitation pH value and aging time, the nanocrystalline powders were successfully derived with chemical homogeneity and superior thermal stability, compared with the single component oxides. The particle size and morphology, surface area, and thermal and phase stabilities were characterized using TEM, TG-DTA, BET and XRD. The sensing tests showed that the Sn-In com-posites exhibit high sensitivity and selectivity for CO and NO2. The introduction of TiO2 enhanced CH4 sensitivity and selectivity, particularly, additives of Pd and Al2O3 as a dopant and surface modification greatly enhanced the sensing properties. The sensitivity depended on the composition of composites, calcination temperature and operating temperature. The optimal values were (25%In2O3- 75%SnO2)-20%TiO2 for ternary composite, 600 and 300℃, respectively. Temperature-programmed de-sorption (TPD) studies were employed to explain the gas adsorption behavior dis-played by the surface of nanocomposites and X-ray photoelectron spectroscopic (XPS) analysis was used to confirm the electronic interactions existing between oxide components. The sensing mechanism of the nanocomposites was attributed to chemical and electronic synergistic effects.

关键词： SnO2-In2O3-TiO2 nanocomposites CO NO2 CH4 gas sensing

Spatial heterogeneity of the driving forces of cropland change in china

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Science china Earth Sciences 2005年第12期48卷 2231-2240页

作者： LIU Xuhua1,2, WANG Jinfeng1, LIU Mingliang4,1 & MENG Bin1,2,3 1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, china 2. Graduate School of the Chinese Academy of Sciences, beijing 100039, china 3. College of Arts and Sciences of beijing union university, beijing 100083, china 4. School of Forestry and Wildlife Sciences, Auburn university, Auburn, Alabama, AL36849, USA Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Graduate School of the Chinese Academy of Sciences Beijing China School of Forestry and Wildlife Sciences Auburn University Auburn Alabama USA College of Arts and Sciences of beijing union university Beijing China

By using digital satellite remote sensing data acquired in 1987―1989 and 1999―2000 and GIS combined with the natural and socio-economic data, this paper drew an integrated zonation of the cropland change and its driving forces in china. The results indicated that the cropland change in the study period was constrained by geographical factors and driven by cli-mate change as well as socio-economic system. Moreover, the regional differences of the drivers for cropland change were significant. In the midwest of china, natural condition changes and geographical background were the main constraints and drivers, while in Eastern china, social and economic changes and economic policies were the main driving forces. The cropland loss was nationwide. The dominant factors to cause this decrease included buildup of developing area to attract foreign capital and technologies, changes of industry structure due to urban in-fluence, the change of employment notions thanks to living standard improvement, rapid ur-banization due to the expansion of cities and towns, the diminished farming net income partly because of the global warming effects, and the rapid economic growth stimulated by the con-venient transportation system. These factors interact and interdepend with each other to cause the cropland loss in china recently. The reasons for the increase of cropland were primarily the cultivation and deforestation by the farmers who want to increase income. This study on the mechnism of LUCC relied on the cropland change integrated classification considering the natural or human factors both inside and outside the region, which provides a new approach to study the integrated regionalization and LUCC mechanism.

关键词： land use change, driving force, integrated classification, spatial statistics, cropland, china.

Experimental study of the movement of control fluid in compound perforation

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Petroleum Science 2009年第4期6卷 389-394页

作者： Zhao Xu Liu Gonghui Li Jun Ding Qingxin Key Laboratory of Petroleum Engineering Ministry of EducationChina University of PetroleumBeijing 102249China beijing union university Beijing 100010China School of Mechanical and Electronic Engineering China University of PetroleumBeijing 102249China

The interaction between the high pressure gas and the control fluid and the movement mechanism of the control fluid in compound perforation were studied by a series of large-scale experiments, where the movement behavior of the control fluid was observed. The curves of measured pressure were analyzed, a mathematical model for the rigid movement of the control fluid was established, and the movement velocity of control fluid was analyzed. Moreover, the velocity from experimental results and velocity from an analytical solution were contrasted. The movement of the control fluid in the initial stage was similar to the rigid movement; however, the propagation of the pressure wave in the control fluid should be taken into account. Experimental results are significant for research on the movement mechanism of control fluid in compound perforation.

关键词： Compound perforation experimental study control fluid gas and liquid interaction mathematical model

Deficit of mitochondria-derived ATP during oxidative stress impairs mouse MII oocyte spindles

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Cell Research 2006年第10期16卷 841-850页

作者： Xiao Zhang~(1,2,*) Xue Qing Wu~(1,3,*) Shuang Lu~(4,5,6) Ying Lu Guo~1 Xu Ma~(4,5,6) ~1Peking university First Hospital,Institute of Urology of Peking university,beijing 100034,china ~2Reproductive and Genetic Center of Peking university First Hospital,beijing 100034,china ~3department of Obstetrics and Gynecology,Shanxi Medical university Second Hospital,Taiyuan 030000,china ~4Reproductive and Genetic Center of National Research Institute for Family Planning,beijing 100038,china ~5department of Genetics, Peking union Medical College, beijing 100038. china ~6 WHO Collaborative Center for Research in Human Reproduction,beijing 100038,china Peking university First Hospital Institute of Urology of Peking University Beijing China Reproductive and Genetic Center of Peking university First Hospital Beijing China department of Obstetrics and Gynecology Shanxi Medical University Second Hospital Taiyuan China Reproductive and Genetic Center of National Research Institute for Family Planning Beijing China department of Genetics Peking Union Medical College Beijing China WHO Collaborative Center for Research in Human Reproduction Beijing China

Although the role of oxidative stress in maternal aging and infertility has been suggested,the underlying mechanismsare not fully *** present study is designed to determine the relationship between mitochondrial functionand spindle stability in metaphase Ⅱ （MⅡ） oocytes under oxidative stress.MⅡ mouse oocytes were treated with H2O2inthe presence or absence of permeability transition pores （PTPs） blockers cyclosporin A （CsA）.In addition,antioxidantN-acetylcysteine （NAC）,F0/F1synthase inhibitor oligomycin A,the mitochondria uncoupler carbonyl cyanide 4-trifluoro-methoxyphenylhydrazone （FCCP） or thapsigargin plus 2.5 mM Ca2+(Th+2.5 mM Ca2+) were used in mechanistic *** analyses ofoocyte spindles and chromosomes were performed and mitochondrial membrane potential（Δψm）,cytoplasmic tree calcium concentration ([Ca2+]c) and cytoplasmic ATP content within oocytes were also *** a time- and H2O2dose-dependent manner,disruption of meiotic spindles was found after oocytes were treated withH2O2,which was prevented by pre-treatment with *** of H2O2led to a dissipation of Δψm,an increasein [Ca2+]cand a decrease in cytoplasmic ATP *** detrimental responses of oocytes to H20,treatment could beblocked by pre-incubation with *** to H2O2,both oligomycin A and FCCP dissipated Δψm,decreased cytoplas-mic ATP contents and disassembled MⅡ oocyte spindles,while high [Ca2+]calone had no effects on spindle *** conclusion,the decrease in mitochondria-derived ATP during oxidative stress may cause a disassembly of mouse MⅡoocyte spindles,presumably due to the opening of the mitochondrial PTPs.

关键词： spindle oxidative stress mitochondria permeability transition pore ATP

An Intelligent Otologic Drill

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Journal of Otology 2010年第2期5卷 104-110页

作者： SHEN Peng1,FENG Guo-dong2,CAO Tian-yang 3,GAO Zhi-qiang 2,LI Xi-sheng 3 1 department of Otolaryngology,Chuiyangliu Hospital of beijing 2 department of Otolaryngology,Peking union Medical College Hospital,Chinese Academy of Medical Sciences and Peking union Medical College,beijing,china 3 School of Information & Engineering,university of Science and Technology beijing,beijing,china department of Otolaryngology Chuiyangliu Hospital of Beijing department of Otolaryngology Peking Union Medical College Hospital Chinese Academy of Medical Sciences and Peking Union Medical College Beijing China School of Information & Engineering University of Science and Technology Beijing Beijing China

Objective To test a modified otologic drill under different drilling conditions for its ability to identify drilling faults and stop *** Based on force analysis and previous works,an otologic drill was modified and equipped with three *** various conditions,the drill was used to simulate three drilling faults and normal drilling,and signals from the drill were analyzed to extract the characteristic signal.A multi-sensor information fusion system and a stop program were designed to recognize drilling faults and stop *** Signals from each sensor changed consistently in response to drilling condition changes,with high repeatability and *** average identification rate was 72.625%,68.575%,70.5% and 81.3% respectively for the three simulated drilling faults and normal *** stop program stopped drilling in 0.2～ 0.3 seconds when a drilling faults was *** This study shows that the forces acting on the drill bit change predictably in the three simulated drilling conditions;that using suitable BP neural networks,the drilling faults can be reliably identified,and that a stop program based upon characteristic signal recognition can stop drilling quickly upon detecting drilling *** lays a foundation for development of a system capable of predicting drilling faults and automatic drill *** studies are being undertaken for practical application of such a system.

关键词： drill otologic surgery force sensor back propagation(BP) neural network