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Temporal Distribution of Diagnostic Biofabrics in the Lower and Middle Ordovician in North China:Clues to the Geobiology of the Great Ordovician Biodiversification Event

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Acta Geologica Sinica(English Edition) 2009年第3期83卷 513-523页

作者： liu jianbo ZHAN Renbin Department of Geology Peking University Beijing 100871 China Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education Peking University Beijing 100871 China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China

The temporal distribution of the diagnostic biofabrics in the Lower and Middle Ordovician in North China distinctly illustrates that the sedimentary systems on the paleoplate have been changed markedly as consequences of the Great Ordovician Biodiversification Event （GOBE）. The pre-GOBE sedimentary systems deposited in Tremadoc display widespread microbialite and flat-pebble conglomerates, and a less extent of bioturbation. Through the transitional period of early Floian, the sedimentary systems in the rest of the Early and Mid- Ordovician change to GOBE type and are characterized by intensive bioturbation and vanishing flat-pebble conglomerates and subtidal microbial sediments. The irreversible changes in sedimentary systems in North China are linked to the GOBE, which conduced the increase in infaunal tiering, the expansion of infaunal ecospace, and the appearance of new burrowers related to the development of the Paleozoic Evolutionary Fauna during the Ordovician biodiversification. Thus, changes in sedimentary systems during the pivotal period of the GOBE were consequences of a steep diversification of benthic faunas rather than the GOBE＇s environmental background.

关键词： bioturbation flat-pebble conglomerate microbial sediment Ordovician biodiversification,geobiology

An improved Bag-of-Words framework for remote sensing image retrieval in large-scale image databases

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International Journal of Digital Earth 2015年第4期8卷 273-292页

作者： Jin Yang jianbo liu Qin Dai Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences BeijingChina University of Chinese Academy of Sciences BeijingChina

Due to advances in satellite and sensor technology,the number and size of Remote Sensing(RS)images continue to grow at a rapid *** continuous stream of sensor data from satellites poses major challenges for the retrieval of relevant information from those satellite *** Bag-of-Words(BoW)framework is a leading image search approach and has been successfully applied in a broad range of computer vision problems and hence has received much attention from the RS ***,the recognition performance of a typical BoW framework becomes very poor when the framework is applied to application scenarios where the appearance and texture of images are very *** this paper,we propose a simple method to improve recognition performance of a typical BoW framework by representing images with local features extracted from base *** addition,we propose a similarity measure for RS images by counting the number of same words assigned to *** compare the performance of these methods with a typical BoW *** experiments show that the proposed method has better recognition performance than that of the BoW and requires less storage space for saving local invariant features.

关键词： remote sensing image retrieval base image Bag-of-Words visual word

Atomistic simulation study of favored compositions of Ni-Nb-Al metallic glasses

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Science China(Technological Sciences) 2018年第12期61卷 1829-1838页

作者： CAI Bei YANG MengHao liu jianbo LI JiaHao liu BaiXin Key Laboratory of Advanced Materials(MOE) School of Materials science and Engineering Tsinghua University

This study investigates the formation process of Ni-Nb-Al metallic glasses. To this end, a long-range n-body potential was constructed for the Ni-Nb-Al ternary metal system, and applied to atomistic simulations. The simulations not only showed the physical origins of the amorphous phase formation, but also quantitatively predicted a hexagonal compositional region that energetically favors the glass formation. The energy difference between the solid solution and metallic glass, which generates the amorphization driving force(ADF), was suggested to indicate the glass-formation ability(GFA) of each alloy. Based on the computed ADFs, the Ni55 Nb25 Al20 alloy exhibited the highest GFA among the Ni-Nb-Al members, implying that the glass formed by this amorphous alloy is more thermodynamically stable than other alloys in the system. In a Voronoi tessellation analysis, the knee point of the coordination-number distribution curve corresponded to the glass-formation region of the Ni-NbAl system.

关键词： interatomic potential atomistic simulation glass-formation ability Ni-Nb-Al system

Temporal distribution of piperocks in Cambrian and Ordovician: A coevolutionary process with changes of paleoenvironment

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Science China Earth Sciences 2012年第1期55卷 26-38页

作者： FANG Liang liu jianbo ZHAN RenBin School of Earth and Space Sciences Peking UniversityBeijing 100871China Key Laboratory of Orogenic Belts and Crustal Evolution(Peking University) Ministry of EducationBeijing 100871China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China

Piperock, a kind of characteristic ichnofabrics in Phanerozoic, was thought to decline gradually from Cambrian to Ordovician. A new compilation on the occurrences of the Cambrian and Ordovician piperocks of China and the world shows that piperocks generally flourished in Cambrian and declined in Ordovician, but a sharp decrease occurred during Middle and Late Cambrian. The case-study on the piperocks from the Lower-Middle Ordovician Hongshiya Formation at Dabaochang of Qiaojia, northern Yunnan Province, Southwest China indicates that the forming and preservation of piperocks were controlled by the depositional environment, the intensities of predation, competition, bioturbation, and the contents of nutrition and oxygen in watermass. A careful study on the development of the Cambrian and Ordovician piperocks suggests that the decrease of nearshore siliciclastic sediments and the low contents of oxygen and nutrition in the watermass may have contributed to the decline of piperocks in Middle and Late Cambrian.

关键词： Piperock Skolithos Cambrian Ordovician temporal distribution Qiaojia northeastern Yunnan

Earth observation satellite data receiving, processing system and data sharing

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International Journal of Digital Earth 2012年第3期5卷 241-250页

作者： Huadong Guo jianbo liu An Li Jianguo Zhang Center for Earth Observation and Digital Earth Chinese Academy of SciencesBeijingChina

The China Remote Sensing Satellite Ground Station was established in *** currently has three receiving stations in the north,west,and south of China,with the capacity to receive data from 15 international and domestic Earth observation satellites covering the entire Chinese territory and 70%of ***,a systematic,integrated,and standardized spatial information service system has been built.A data-sharing project for medium-resolution Earth observation satellites has been conducted and plays an important role in land,ocean,and atmospheric resource investigation and environmental monitoring.

关键词： Earth observation data receiving data sharing remote sensing applications

Different atomic structures observed from ternary Ni-Nb-Ta metallic glasses obtained by ion beam mixing

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Science China(Technological Sciences) 2013年第8期56卷 1842-1846页

作者： WANG YuanYu liu jianbo DAI Ye liu BaiXin Advanced Materials Laboratory School of Materials Science and EngineeringTsinghua University

Four sets of ternary Ni-Nb-Ta multilayered samples with overall compositions of Ni69Nb8Ta23,Ni55Nb13Ta32,Ni42Nb16Ta42 and Ni29Nb18Ta53,respectively were prepared and subjected to 185 keV xenon ion beam *** experimental results showed that in the four Ni-Nb-Ta multilayered samples,metallic glasses could all be obtained at appropriate doses,supporting the prediction directly from a proven realistic Ni-Nb-Ta interatomic potential through molecular dynamics simulations,and that two different atomic structures were observed,as in the corresponding selected area diffraction patterns,the locations of the diffused bands reflected from the metallic glass phases were observed at different angles for the Ni69Nb8Ta23 and Ni29Nb18Ta53 metallic ***,Voronoi tellessation analysis indicated that the observed difference in atomic structures could be attributed to the distinct coordinate number spectra,i.e.,the spectrum of the Ni69Nb8Ta23 metallic glass has its coordinate number(CN) equal to 13 as dominating atomic configuration(with a weight of about 27%),whereas for the Ni29Nb18Ta53 metallic glass,CN=14 is the dominating atomic configuration(also about 27%).Moreover,the distinct atomic configurations of the obtained Ni-Nb-Ta metallic glasses could be correlated to the structures of the constituent metals of the ternary Ni-Nb-Ta system,as the first neighbor of fcc is 12 and the sum of the first and second neighbors of bcc is 14,implying the structural heredity did play a role in metallic glass formation.

关键词： ion beam mixing molecular dynamics coordinate number structural heredity

Biodiversity of Early-Middle Ordovician acritarchs and sealevel changes in South China

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Chinese Science Bulletin 2005年第20期50卷 2362-2368页

作者： YAN Kui LI Jun liu jianbo Nanjing Institute of Geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China School of Earth and Space Sciences Peking University Beijing 100871 China Gradate University of Chinese Academy of Sciences Beijing 100049 China

As the primary producers, acritarchs represent the base of the food chain in the Paleozoic marine ecosystem which links with the evolution of acritarchs. Based on high precision quantitative research, much information about Paleozoic marine ecosystem is provided. A quantitative analysis of Early-Middle Ordovician acritarch diversity changes in the Meitan Formation, Honghuayuan section, Tongzi, Guizhou is made and the the acritarch diversity curves are compared with sea level curves. We found that acritarch diversity changes were related to sea level changes during the Early-Middle Ordovician. Whereas sea level rose, and acritarch diversity also increased. An inshore-offshore model of acritarchs best explains the relative abundance changes of some acritarch taxa in relation to sea level changes.

关键词：中国海平面奥陶纪古生地层环境参数

An improved SVM model for relevance feedback in remote sensing image retrieval

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International Journal of Digital Earth 2014年第9期7卷 725-745页

作者： Caihong Ma Qin Dai jianbo liu Shibin liu Jin Yang Center for Earth Observation and Digital Earth Chinese Academy of SciencesBeijing 100094China

With the rapid development of satellite remote sensing technology and an ever-increasing number of Earth observation satellites being launched,the global volume of remotely sensed imagery has been growing *** the variety of remotely sensed data has increasingly been complex and *** is also hard to efficiently and intelligently retrieve what users need from a massive database of *** paper introduces an improved support vector machine(SVM)model,which optimizes the model parameters and selects the feature subset based on the particle swarm optimization(PSO)method and genetic algorithm(GA)for remote sensing image *** results from an image retrieval experiment show that our method outperforms traditional methods such as GRID,PSO,and GA in terms of consistency and stability.

关键词： content-based remote sensing image retrieval relevance feedback support vector machines particle swarm optimization genetic algorithm

Metallic glass formation in the ternary Ni-Nb-Mo system by ion beam mixing

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Science China(Technological Sciences) 2012年第8期55卷 2206-2211页

作者： LI Yang WANG TongLe DING Ning liu jianbo liu BaiXin Advanced Materials Laboratory Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Glass forming ability of the ternary Ni-Nb-Mo system was studied by ion beam mixing of the Ni-Nb-Mo multilayered *** the experiment,metallic glasses *** alloys were formed in the Ni51Nb19Mo30,Ni52Nb35Mo13,Ni61Nb15Mo24 and Ni72Nb20Mo8 multilayered films,while only solid solutions were obtained in the Ni24Nb29Mo47 and Ni26Nb53Mo21 multilayered *** turned out that the Ni concentration played a dominating role in affecting the glass-forming ability of the ***,thermodynamic calculations predicted a favored composition region for metallic glass formation,matching well with the observations from ion beam mixing.

关键词： metallic glasses ion beam mixing the Ni-Nb-Mo system