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Online detection of bursty events and their evolution in news streams

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第5期11卷 340-355页

作者： Wei chen Chun chen li-jun ZHANC Can WANG Jia-jun BU Zhejiang Laboratory of Service Robot Zhejiang Universit) Hangzhou 310027 China

Online monitoring of temporally-sequenced news streams for interesting patterns and trends has gained popularity in the last *** this paper,we study a particular news stream monitoring task:timely detection of bursty events which have happened recently and discovery of their evolutionary patterns along the ***,a news stream is represented as feature streams of tens of thousands of features(i.e.,*** news story consists of a set of keywords.).A bursty event therefore is composed of a group of bursty features,which show bursty rises in frequency as the related event *** this paper,we give a formal definition to the above problem and present a solution with the following steps:(1) applying an online multi-resolution burst detection method to identify bursty features with different bursty durations within a recent time period;(2) clustering bursty features to form bursty events and associating each event with a power value which reflects its bursty level;(3) applying an information retrieval method based on cosine similarity to discover the event's evolution(i.e.,highly related bursty events in history) along the *** extensively evaluate the proposed methods on the Reuters Corpus Volume *** results show that our methods can detect bursty events in a timely way and effectively discover their *** power values used in our model not only measure event's bursty level or relative importance well at a certain time point but also show relative strengths of events along the same evolution.

关键词： Online event detection Event’s evolution News stream Affinity propagation

Responses of Ammonia-Oxidizing Bacteria and Archaea in Two Agricultural Soils to Nitrification Inhibitors DCD and DMPP: A Pot Experiment

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Pedosphere 2013年第6期23卷 729-739页

作者： GONG Ping ZHANG li-li WU Zhi-Jie chen Zhen-Hua chen li-jun Institute of Applied Ecology Chinese Academy of Sciences University of Chinese Academy of Sciences State Key Laboratory of Forest and Soil Ecology Institute of Applied EcologyChinese Academy of Sciences

Taking two important agricultural soils with different pH, brown soil （Hap-Udic Luvisol） and cinnamon soil （Hap-Ustic Luvisol）, from Northeast China, a pot culture experiment with spring maize （Zea mays L.） was conducted to study the dynamic changes in the abundance and diversity of soil ammonia-oxidizing bacteria （AOB） and ammonia-oxidizing archaea （AOA） populations during maize growth period in response to the additions of nitrification inhibitors dicyandiamide （DCD） and 3,4-dimethylpyrazole phosphate （DMPP） by the methods of real-time polymerase chain reaction （PCR） assay, PCR-denaturing gradient gel electrophoresis （DGGE）, and construction of clone library targeting the amoA gene. Four treatments were established, i.e., no urea （control）, urea, urea plus DCD, and urea plus DMPP. Both DCD and DMPP inhibited growth of AOB significantly, compared to applying urea alone. Soil bacterial amoA gene copies had a significant positive linear correlation with soil nitrate content, but soil archaeal amoA gene copies did not. In both soils, all AOB sequences fell within Nitrosospira or Nitrosospira-like groups, and all AOA sequences belonged to group 1.1b crenaxchaea. With the application of DCD or DMPP, community composition of AOB and AOA in the two soils had less change except that the AOB community composition in Hap-Udic Luvisol changed at the last two growth stages of maize under the application of DCD. AOB rather than AOA likely dominated soil ammonia oxidation in these two agricultural soils.

关键词： ammonium clone library denaturing gradient gel electrophoresis nitrate real-time polymerase chain reaction

NUMERICAL SIMULATION OF WAVE-INDUCED CURRENT WITH VERTICALLY VARIED RADIATION STRESS

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Journal of Hydrodynamics 2010年第2期22卷 254-259页

作者： ZHANG Jing liANG Bing-chen li Hua-jun College of Engineering Ocean University of China Qingdao 266100 China

This article analyzes the vertical structure of the onshore current including the wave-induced current by an equation developed for the radiation stress against water depth.A coupled model COHERENS-SED is adopted to calculate the wave,tidal current,wave-induced current and sediment *** applying the new model to Yangpu Bay,its reliability is *** an ideal coastal domain is defined to simulate the nearshore current and wave setup with normal incident *** numerical and experimental results for the vertical structure show two undertows,also a visible setup in the surf *** demonstrates the importance of the radiation stress in wave-induced currents and mean water levels（set-up/down）.

关键词： COHERENS-SED radiation stress wave-induced current setup

Stability of Two-Component Bose-Einstein Condensates in Bessel Optical Lattices

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Communications in Theoretical Physics 2008年第6期49卷 1519-1526页

作者： chen Hai-jun li Hao-Cai XUE Ju-Kui College of Physics and Electronics Engineering Northwest Normal University Lanzhou 730070 China

The stability of the ground state of two-component Bose-Einstein condensates （BEGs） loaded into the central well of an axially symmetric Bessel lattices （BLs） potential with attractive or repulsive atoms interactions is studied using the time-dependent Gross-Pitaevskii equation （GPE）. By using the variational method, we find that stable ground state of two-component BEGs can exist in BLs. The BLs＇s depth and the intra-species atom interaction play an important role in the stability of ground state. The collapse of two-component BEGs in BLs is also studied and a collapse condition for trapped two-component BEGs is obtained. It is shown that the two-component BEGs exhibit rich collapse dynamics. That is, the two-component BEGs can collapse in the system with both intra- and inter-attractive, or with intra-attractive and inter-repulsive, or with intra-repulsive and inter-attractive atom interactions. Furthermore, the control of the collapse of the two-component BEGs in BLs is discussed in detail. The stability diagram of the ground state in parameter space is obtained. The results show that the collapse of two-component BEGs can be controlled by temporal modulation of the atom interaction.

关键词： two-component Bose-Einstein condensates Gross-Pitaevskii equation Bessel optical lattice ground state

Sr-Nd isotope geochemistry of eolian dust of the arid-semiarid areas in China: Implications for loess provenance and monsoon evolution

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Chinese Science Bulletin 2006年第12期51卷 1401-1412页

作者： RAO Wenbo YANG Jiedong chen jun li Gaojun Department of Earth Sciences Nanjing University Nanjing 210093 China

Minerals and rocks have distinct 87Sr/86Sr and 143Nd/144Nd ratios, depending on their geological origin and ages, and these isotope ratios are less altered than elemental composition during transport in the atmosphere or after deposition as sediments, thus stable isotopes of Sr and Nd have great potential as tracers for provenance and trans- port of materials. During the hypergene process, Sr isotope ratios of sediments are controlled by their parent rocks, particle sizes and chemical weathering. In general, the higher the Sr isotope ratios of parent rocks, and/or the more the fine-grained fractions, and/or the stronger the chemical weathering, thus the higher the Sr isotope ratios of sediments. On the contrary, there are lower Sr isotope ratios of sedi- ments. Nd isotope ratios of sediments, independent of their particle sizes and chemical weathering, are only associated with parent rocks. For the prove- nance of the Chinese Loess Plateau, different re- seachers drew discordant and even contradictory conclusions by using the method of Sr-Nd isotopic tracing. From the previous Nd isotope data, it is con- sidered that the Tarim Basin, deserts in the central and west parts of Inner Mongolia and the Tibetan Plateau are the main sources of the Chinese Loess Plateau, and are also manufacturers for eolian dust of the Far East regions, together with the Chinese Loess Plateau. Sr isotope ratios of eolian dust are solely affected by wind sorting and weather- ing-pedogenesis due to its homogeneous composi- tion in the Chinese Loess Plateau. Wind sorting isrelated to the East Asian winter monsoon but weath- ering-pedogenesis is mainly associated with the East Asian summer monsoon. Studies on Sr isotopic compositions of the loess-paleosol sequence suggest that 87Sr/86Sr ratios in acid-soluble materials are an index for chemical weathering intensity of the Chi- nese Loess Plateau, indicating the East Asian sum- mer monsoon variations, whereas 87Sr/86Sr ratios in acid-insoluble m

关键词：锶-钕同位素季风黄土干旱-半干旱地区地球化学

Influence of furfural concentration on growth and ethanol yield of Saccharomyces kluyveri

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Journal of Environmental Sciences 2007年第12期19卷 1528-1532页

作者： LU Peng chen li-jun li Guo-xue SHEN Shi-hua WANG li-li JIANG Qi-yang ZHANG Jin-feng College of Resources and Environment China Agricultural University Beijing 100094 China Institute of Botany Chinese Academy of Sciences Beijing 100093 China

Furfural is an important inhibitor in ethanol fermentation process using lignocellulosic hydrolysates as raw materials. In order to find out the furfural concentration range in which furfural inhibits the fermentation process, we used one strain Saccharomyces kluyveri selected from soil and cultured in several different furfural content media under low glucose concentration condition. Experiment results showed that microorganism growth was stimulated and dry cell weight decreased when furfural concentration in the medium was 0.25 mg/ml. Furfural had negative effect on cell growth when its concentration was above 1.00 mg/ml. At the same time, the strain growed better and had a higher glucose consumption rate in 5% original glucose concentration condition than in 3% original glucose concentration condition. The results showed that appropriate exaltation of original glucose concentration in stalk hydrolysates will increase the strain resistance to furfural.

关键词： furfural concentration Saccharomyces kluyveri fermentation growth ethanol yield

Quark Transport Properties in the Region of Coexistence of Both Hadronic and QGP Phases

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Communications in Theoretical Physics 2001年第7期36卷 47-52页

作者： chen Xiang-jun li Hong WANG Gang ZHANG Wei-Ning HUO Lei Department of Physics Harbin Institute of Technology Harbin 150001 China Department of Physics Harbin Institute of Technology Harbin 150001 China Department of Physics Harbin Institute of Technology Harbin 150001 China Department of Physics Harbin Institute of Technology Harbin 150001 China Department of Physics Harbin Institute of Technology Harbin 150001 China

The physical picture of coexistence of both hadronic and QGP phases is given by Friedberg and T.D. Lee's nontopology soliton model. The transport properties of quark in color space and spin space in a system of two-ph... 详细信息

关键词： hadron, quark-gluon plasma, soliton, transport property

BOTTOM SHEAR STRESS UNDER WAVE-CURRENT INTERACTION

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Journal of Hydrodynamics 2008年第1期20卷 88-95页

作者： liANG Bing-chen li Hua-jun LEE Dong-yong College of Engineering Ocean University of China Qingdao 266100 China Coastal and Harbour Engineering Research Center Korea Ocean Research and Developmcnt Institute Ansan Korea

The present work adopts the COHERENS-SWAN model developed by the first author through coupling three-dimensional hydrodynamic model （COHERENS） and third-generation wave model （SWAN）. Inside the COHERENS-SWAN, the SWAN is regarded as a subroutine and the time- and space-varying current velocity and surface elevation are obtained from the COHERENS. Wave-enhanced bottom shear stress, wave induced surface mixing length and wave dependent surface drag coefficient have been introduced into the COHERENS. Secondly, as wave-enhanced bottom shear stress （＂bottom shear stress＂ described as BSS sometimes in this article） is concerned, a modified bottom shear stress Grant and Madsen model which introduces random wave field is given and introduced to COHERENS-SWAN. COHERENS-SWAN is also adopted to simulate three-dimensional flow in the Yellow River Delta with wave-current co-existing. Four numerical experiments were given to study the effects of wave-current interaction on enhancing bottom shear stress. The simulated current velocities, wave height and wave period match well with field measurement data. The simulated significant wave height and wave period for the case with considering the effects of current can give better agreement with measurement data than the case without involving the effects of current. The introduction of random wave generates lower the bottom shear stress than the case without introducing it. There are obvious differences between bottom shear stress of two way interaction and one way interaction. Velocity field obtained by the COHERENS-SWAN is reasonable according to previous studies and measurements.

关键词： Yellow River Delta COHERENS SWAN wave-current interaction bottom shear stress

IMPROVING 9-INTERSECTION MODEL BY REPLACING THE COMPLEMENT WITH VORONOI REGION

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Geo-Spatial Information Science 2000年第1期3卷 1-10页

作者： chen jun li chengming li Zhilin Gold C M National Geomatics Center of China Beijling China

9-intersection model is the most popular framework used for formalizing the spatial relations between two spatial objectsA andB. It transforms the topological relationships between two simple spatial objectsA andB into point-set topology problem in terms of the intersections ofA’s boundary (?A), interior (A 0) and (A ?) withB’s boundary (?B), interior (B 0) and exterior (B ?). It is shown in this paper that there exist some limitations of the original 9-intersection model due to its definition of an object’s exterior as its complement, and it is difficult to distinguish different disjoint relations and relations between complex objects with holes, difficult or even impossible to compute the intersections with the two object’s complements (?A∩B ?,A 0∩?B ?,A ?∩?B,A ?∩B 0 andA ?∩B ?)since the complements are infinitive. The authors suggest to re-define the exterior of spatial object by replacing the complement with its Voronoi region. A new Voronoi-based 9-intersection (VNI) is proposed and used for formalizing topological relations between spatial bojects. By improving the 9-intersection model, it is now possible to distinguish disjoint relations and to deal with objects with holes. Also it is possible to compute the exterior-based intersections and manipulate spatial relations with the VNI.

关键词： 9-intersection model Voronoi region topological relationship