检索结果-南通市图书馆

N DIMENSIONAL FINITE WAVELET FILTERS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2003年第5期21卷 595-602页

作者： Si-long Peng (NADEC, institute of Automation, chinese {2. of sciences, beijing 100080, china) NADEC Institute of Automation Chinese Academy of Sciences 北京 100080

In this paper, a large class of n dimensional orthogonal and biorthognal wavelet filters (lowpass and highpass) are presented in explicit expression. We also characterize orthogonal filters with linear phase in this c... 详细信息

关键词： n Dimension Linear phase Wavelet filters.

Transformations and non-degenerate maps

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2005年第Z1期48卷 195-205页

作者： LI Baokui & WANG Yuefei institute of Mathematics, academy of Mathematics and System {2., chinese academy of {2., beijing 100080, china Graduate School, chinese academy of {2., beijing 100080, china institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China

We shall prove the equivalences of a non-degenerate circle-preserving map and a M(o)bius transformation in ^Rn, of a non-degenerate geodesic-preserving map and an isometry in Hn of a non-degenerate line-preserving map and an affine transformation in Rn. That a map is non-degenerate means that the image of the whole space under the map is not a circle, or geodesic or line respectively. These results hold without either injective or surjective, or even continuous assumptions, which are new and of a fundamental nature in geometry.

关键词： M(o)bius transformation, circle-preserving map, non-degenerate map.

Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2000年第1期16卷 50-54页

作者： Lingchuan LI (institute of Chemical Metallurgy, chinese {2. of sciences, beijing 100080, china) institute of Chemical Metallurgy Chinese Academy of Sciences Beijing 100080 China

Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.

关键词： Al Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

PROBABILISTIC NUMERICAL APPROACH FOR PDE AND ITS APPLICATION IN THE VALUATION OF EUROPEAN OPTIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2001年第6期19卷 591-600页

作者： Dong-sheng Wu (institute of Systems Science, academy of Mathematics and Systems {2., chinese academy of {2., beijing 100080, china ) 中科院系统科学所北京 100080

Presents a probabilistic numerical approach for a class of probabilistic differential equation. Application of the Brownian motion and Monte-Carlo method; Application in the valuation of European Options.

关键词： Brownian motion probabilistic numerical solution European Options

A novel operation mode for spaceborne polarimetric SAR

在线全文

学校读者我要写书评

暂无评论

Science china(Information sciences) 2011年第4期54卷 884-897页

作者： QI WeiKong 1,2.& YU WeiDong 1 1 institute of Electronics,chinese {2. of sciences,beijing 100190,china 2.Graduate School of chinese {2. of sciences,beijing 100039,china institute of Electronics Chinese Academy of Sciences Beijing China Graduate School of chinese academy of {2. Beijing China

A novel operation mode for spaceborne polarimetric SAR,named polarization space-division adding polarization code-division (PSD-PCD) operation mode,is proposed in this paper through combining polarimetric SAR with elevation digital beam-forming (DBF) on *** a pulse repetition interval the up-chirp LFM sub-pulse is transmitted with horizontal polarization antenna,and with some delay the down-chip LFM subpulse is transmitted with vertical polarization antenna to realize code *** every sub-aperture receives returns from ground,SAR system uses range DBF to separate echoes relative to different sub-pulses in order to realize space *** system PRF is equal to that of single-polarization SAR,and elevation DBF help reduce range ambiguity ***,the main system parameters,including PRF,delay between two sub-pulses,radar equation and ambiguity are analyzed and compared with those of single-polarization *** results demonstrate the feasibility and validity of PSD-PCD operation mode.

关键词： spaceborne synthetic aperture radar (SAR) polarimetry digital beamforming (DBF) operation mode ambiguity ratio polarization space-division polarization code-division

Effect of concentration on surfactant micelle shapes——A molecular dynamics study

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china Chemistry 2005年第5期48卷 470-475页

作者： GAO Jian1,2. GE Wei1 & LI Jinghai1 1. Multiphase Reaction Laboratory, institute of Process Engineering, chinese {2. of sciences, beijing 100080, china 2. Graduate School of The chinese {2. of sciences, beijing 100085, china Multiphase Reaction Laboratory Institute of Process Engineering Chinese Academy of Sciences Beijing China Graduate School of The chinese academy of {2. Beijing China

Many aspects of the behavior of surfactants have not been well understood due to the coupling of many different mechanisms. Computer simulation is, therefore, attractive in the sense that it can explore the effect of different mechanisms separately. In this paper, the shapes, structures and sizes of sodium dodecylbenzenesulfonate (SDBS) micelles under different con-centrations in an oil/water mixture were studied via molecular dynamics (MD) simulations using a simplified atomistic model which basically maintains the hydrophile and lipophile properties of the surfactant molecules. Above the critical micellar concentration (cmc), surfactant molecules ag-gregate spontaneously to form a wide variety of assemblies, from spherical to rodlike, wormlike and bilayer micelles. Changes in their ratios of the principle moments of inertia (g1/g3, g2.g3) in-dicated the transition of micelle shapes at different concentrations. The aggregation number of micelle is found to have a power-law dependence on surfactant concentration.

关键词： surfactant, MD simulation, sodium dodecylbenzenesulfonate, micelle shape.

The^(40)Ar/^(39)Ar age record of formation and uplift of the blueschists and eclogites in the western Tianshan Mountains

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2000年第11期45卷 1047-1052页

作者： GAO Jun, ZHANG Lifei & LIU Shengwei1. institute of Geology, chinese academy of geological sciences, {2. 100037, china 2. Department of Geology, Peking University, {2. 100871, Chin institute of Geology Chinese Academy of Geological Sciences Beijing China Department of Geology Peking University Beijing China

The 40Ar/39Ar ages indicate that the eclogite facies rocks of the Hasiate slice in the western Tianshan Mountains were formed at the early stage of Devonian （401 Ma） and had been uplifted to the greenschist facies tectonic level in the middle stage of Devonian （381 Ma）. The formation and uplift of the blueschists of the Akesayi slice are constrained to the late stage of Devonian （370-364 Ma）. The different tectonic slices in the high-pressure metamorphic belt have experienced the different uplift history.

关键词： western Tianshan Mountains eclogite blueschist 40Ar/39Ar age.

Relationships between tree-ring width index and NDVI of grassland in Delingha

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2006年第9期51卷 1106-1114页

作者： HE Jicheng1,3 & SHAO Xuemei1,2.. institute of Geographical sciences and Natural Resources Research, {2. academy of sciences, beijing 100101, china 2. institute of Tibetan Plateau Research, {2. academy of sciences, beijing 100085, china 3. Graduate School of {2. academy of sciences, beijing 100039, china institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Graduate School of chinese academy of {2. Beijing China institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

Using five well-replicated Qilian juniper (Sabina przewalskii Kom.) tree-ring width index se- ries, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982.to 2.01, the relationships between tree-ring width index, NDVI of grassland, and climatic data were analyzed firstly. Then, the relationship between tree-ring width index and NDVI of grassland was explored. The re- sults showed that: (1) Temperature and precipitation in June influenced tree-ring width index and NDVI of grassland deeply in Delingha. (2. There were sig- nificant relationships between five tree-ring width index series (DLH1-DLH5) and monthly NDVI of grassland from June to September, with the most significant relationship being between tree-ring width index series and NDVI of grassland in August. (3) The PC1 (the first principal component derived from DLH1-DLH5 series) exhibited good agreement with monthly NDVI of grassland in the grass growth sea- son (from June to September) and the averaged NDVI in the growth season, which was attributed to their common responses to water-supply limit in Delingha. This study may allow an increase in studying the past dynamics of grassland in Delingha in that the variation of grassland NDVI during the last millennium has been reconstructed from PC1.

关键词：圆柏祁连山 NDVI 草原年轮宽度指数

A new species of Leptocycas (Zamiaceae) from the Upper Triassic sediments of Liaoning Province,china

在线全文

学校读者我要写书评

暂无评论

Journal of Systematics and Evolution 2010年第4期48卷 286-301页

作者： 1,2.3Jian-Wei ZHANG 2.ian-Xin YAO 1Jia-Rui CHEN 1Cheng-Sen LI 1(State Key Laboratory of Systematic and Evolutionary Botany,institute of Botany,chinese {2. of sciences,beijing 100093,china) 2.State Key Laboratory of Stratigraphy and Paleontology,institute of Geology,chinese {2. of geological sciences,beijing 100037,china) 3(Graduate University,chinese {2. of sciences,beijing 100049,china) (State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Beijing 100093 China) (State Key Laboratory of Stratigraphy and Paleontology Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China) (Graduate University Chinese Academy of Sciences Beijing 100049 China)

A new cycad,Leptocycas yangcaogouensis ***.,was found in sediments from the Late Triassic in western Liaoning,*** pinnately compound leaves(Pseudoctenis type)are screwed in a crown on the stem *** leaflets are linear,with parallel veins and decurrent bases on the *** leaf bases are *** cataphylls intermix with the *** female cone is ovoid in *** characteristics of the new plant are more similar to those of Leptocycas gracilis,a Triassic cycad from North America,but the new species differs from *** in the size of its stem(7–8 vs.3–5 cm in diameter,respectively),leaves(length×width 100×16 vs.30×7 cm,respectively)and leaf density along the stem(4–6 vs.1–2.bases/1 cm length,respectively).Both *** and ***,having leaves of the Pseudoctenis type,show a closer relationship to the extant Dioon of *** present study provides evidence for the origin of the genus Dioon,which may have come from Leptocycas plants of the *** would be assumed that the extent cycads in Zamiaceae originate from the pteridosperms in the Late Paleozoic and have evolved through the stage of *** and *** in Late Triassic,and reaching the extant Dioon.

关键词： china Cycadales Leptocycas Upper Triassic Zamiaceae