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A New Model for the Genesis of Natural Gases——Multi-source Overlap, Multi-stage continuity. TypeControlled by Main Source and Nomenclature by Main Stage (Ⅱ)——Multi-stage continuity.and Nomenclature by Main Stage

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Science China Chemistry 1994年第3期37卷 494-501页

作者：徐永昌沈平 State Key Laboratory of Gas Geochemistry Lanzhou Institute of Geology Academia Sinica Lanzhou 730000 PRC

The generation of natural gases involves several stages and the various stages are of continuous transition. This is another feature of natural gas generation. The term 'multi-stage' is relative mainly to oil-generating threshold value and liquid window. The evolution of organic matter is affected by different epigene agencies and natural gases differing in geochemical properties such as biogenic gas (bacterial gas), thermocatalytic gas and pyrolytic gas could be produced at different stages of the evolution of organic matter. The proposal of bio-thermocatalytic transitional-zone gas presents a pattern of mutual linking and continuous transition of natural gases originated at different *** the genetic classification of natural gases, the nomenclature of a certain gas is based mainly on the epigene agency which is responsible for its formation, for example, biogenic gas, pyrolytic gas. That is the 'nomenclature by the main stage' described in this study. On account of the continuity.of gas generation, if a sedimentary basin has not undergone obvious uplifting and denudation, natural gases formed at different stages would constitute overlap gas reservoirs, i. e. accumulative gas reservoirs. If in the process of gas generation, the sedimentary basin has undergone uplifting and denudation followed by re-descending, gases generated under such geological settings would be partly scattered. This is called the instantaneous preservation. All this would exert the influence on the geochemical properties of natural gases in the natural gas reservoirs formed under the conditions described above. The use of the new model described in this paper to study the questionable mechanisms of genesis of some gas reservoirs would yield more satisfactory results.

关键词： genesis of natural gases multi-stage continuity.

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Automatic LOD selection using viewpoint entropy

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第2期8卷 275-289页

作者： Xiaodong Wang Fengju Kang Hao Gu College of Marine Engineering Northwestern Polytechnical University Xi’an 710072 P.R.China National Key Laboratory of Underwater Information Process and Control Xi’an 710072 P.R.China

Discrete Level of Detail (LOD) strategy is an effective solution for balancing the inherentcontradiction between quality and speed in computer graphics. However, application ofthis strategy requires both the appropriate selection approach and the visually comfortable transition procedure to reduce the popping effects introduced by switching betweendifferent levels. In this paper, a novel automatic LOD selection method based on viewpoint entropy was proposed. Firstly, the traditional calculation method of viewpointentropy contained in a scene was improved for the preprocessing of LOD models. Then,the runtime rendering scheme combined with our selection method was designed forbalance of frame rate during real-time rendering, and a novel smoothing LOD transitionstrategy based on Alternate Frame Rendered (ALR) was put forward for eliminationof popping effects. Finally, an example of complex scene combined with our proposalwas researched to verify its real-time performance and ability in holding continuity.ofrendered images. Experimental studies show the effectiveness for stabilizing frame rateand improvements in reducing loss of continuity.

关键词： LOD selection viewpoint entropy smooth transition real-time rendering continuity.

Increments and sample path properties of Gaussian processes

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Chinese Science Bulletin 1999年第18期44卷 1633-1641页

作者： Zhengyan Lin Lixin Zhang Zhejiang Univ Dept Math Hangzhou 310028 Peoples R China

The latest results in the field on increments and sample path properties of Gaussian processes are introduced.

关键词： Gaussian process increments sample path property moduli of continuity.

continuity.OF l^2-VALUED TWO-PARAMETER ORNSTEIN UHLENBECK PROCESSES

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Applied Mathematics(A Journal of Chinese Universities) 2001年第4期16卷 423-429页

作者： Wen JiweiDept. of Math.,Zhejiang Univ.(Xixi Campus),Hangzhou 310028. Dept. of Math. Zhejiang Univ Hangzhou

Let {Y (t);t= (t 1,t 2)≥0}={X k(t 1,t 2);t 1≥0,t 2≥0} ∞ k=1 be a sequence of two parameter Ornstein Uhlenbeck processes (OUP 2) with coefficients α k>0,β k>0 . A Fernique type inequality is established and the sufficient condition for a.s. l 2 continuity.of Y(·) is studied by means of the inequality.

关键词： l 2 valued two parameter Ornstein Uhlenbeck processes Fernique type inequality continuity.

An Evaluation of BeiDou Navigation Satellite System

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An Evaluation of BeiDou Navigation Satellite System