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VARIATIONS ON A THEME BY EULER

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Journal of Computational Mathematics 1998年第2期16卷 97-106页

作者： Kang Feng Dao-liu Wang (State key laboratory of Scientific and Engineering Computing, ICMSEC, chinese academy of sciences, beijing 100080, china) 中科院计算数学与科学工程计算所科学与工程计算国家重点实验室北京

The oldest and simplest difference scheme is the explicit Euler method. Usually, it is not symplectic for general Hamiltonian systems. It is interesting to ask: Under what conditions of Hamiltonians, the explicit Euler method becomes symplectic? In this paper, we give the class of Hamiltonians for which systems the explicit Euler method is symplectic. In fact, in these cases, the explicit Euler method is really the phase how of the systems, therefore symplectic. Most of important Hamiltonian systems can be decomposed as the summation of these simple systems. Then composition of the Euler method acting on these systems yields a symplectic method, also explicit. These systems are called symplectically separable. Classical separable Hamiltonian systems are symplectically separable. Especially, we prove that any polynomial Hamiltonian is symplectically separable.

关键词： Hamiltonian systems symplectic difference schemes explicit Euler method nilpotent symplectically separable

Functional evolutionary developmental biology (evo-devo) of morphological novelties in plants

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Journal of Systematics and Evolution 2010年第2期48卷 94-101页

作者： Jisi ZHANG Ying TIAN Li WANG Chaoying HE (State key laboratory of Systematic and Evolutionary Botany,institute of Botany,chinese academy of sciences,beijing 100093,china) (State key laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Beijing 100093 China)

The origin of morphological and ecological novelties is a long-standing problem in evolutionary *** these processes requires investigation from both the development and evolution standpoints,which promotes a new research field called "evolutionary developmental biology" (evo-devo).The fundamental mechanism for the origin of a novel structure may involve heterotopy,heterochrony,ectopic expression,or loss of an existing regulatory ***,the morphological and ecological traits controlled by the regulatory genes may be gained,lost,or regained during *** morphological novelties,for example,include homeotic alterations (related to organ identity),symmetric diversity,and changes in the size and morphology of the floral *** gains and losses can potentially arise through modification of the existing regulatory ***,we review current knowledge concerning the origin of novel floral structures,such as "evolutionary homeotic mutated flowers",floral symmetry in various plant species,and inflated calyx syndrome (ICS) within *** evo-devo of the morphological novelties is a central theme of plant evolutionary *** addition,the discussion is extended to consider agronomic or domestication-related traits,including the type,size,and morphology of fruits (berries),within Solanaceae.

关键词： biodiversity development evolution functional evo-devo heterochrony heterotopy morphological novelty

Periodicity of Retzius lines in fossil Pongo from South china

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chinese Science Bulletin 2012年第7期57卷 790-794页

作者： HU Rong1,2,3, ZHAO LingXia1,2 & WU XinZhi2 1 key laboratory of Evolutionary Systematics of Vertebrates, institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of sciences, beijing 100044, china 2 laboratory of Human Evolution, institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of sciences, beijing 100044, china 3 Graduate University of chinese academy of sciences, beijing 100049, china key laboratory of Evolutionary Systematics of Vertebrates Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China laboratory of Human Evolution Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China

Periodicity of Retzius lines is a key factor in dental development. In this study, we examined the periodicity of Retzius lines in fossil Pongo from South china using polarized light microscope observation of dental ground sections. The periodicities all of the 15 teeth were 9 d. Comparisons of periodicity were made with extant primates, fossil apes and hominins. Periodicity of fossil Pongo from South china was relatively long but fell within the variation of extant Pongo, Gorilla and modern human, and longer than periodicity of Pan and other extant primates. Fossil Pongo from South china was similar to Lufengpithecus and Sivapithecus, shorter than Gigantopithecus and longer than European and African fossil apes and most early hominins in periodicity. Generally, the periodicities of Asian large-body fossil apes were longer than the periodicities of European and African large-body fossil apes in Miocene. Difference among species and trend of evolution in periodicity were analyzed and discussed. We found that periodicity might gradually increase from Proconsul in early Miocene to several fossil apes in Miocene and then Gigantopithecus in Pleistocene. In addition, this study made correlate analysis between periodicity and body mass respectively in males and females of six extant apes and five fossil apes, and found that periodicity positively correlated with body mass.

关键词：周期性变化中国南方大猩猩化石灵长类动物早中新世类人猿显微镜观察

Features and distribution patterns of chinese endemic seed plant species

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Journal of Systematics and Evolution 2011年第2期49卷 81-94页

作者： 1,2,3 Ji-Hong HUANG 1,4 Jian-Hua CHEN 5 Jun-Sheng YING 1 Ke-Ping MA 1 (State key laboratory of Vegetation and Environmental Change, institute of Botany, chinese academy of sciences, beijing 100093, china) 2 (Graduate University of chinese academy of sciences, beijing 100049, china) 3 (Center for Documentation and Information, institute of Botany, chinese academy of sciences, beijing 100093, china) 4 (Zhejiang Normal University, Jinhua 321004, china) 5 (Research Center of Systematic and Evolutionary Botany, institute of Botany, chinese academy of sciences, beijing 100093, china) (State key laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing 100093 China) (Graduate University of chinese academy of sciences Beijing 100049 China) (Center for Documentation and Information Institute of Botany Chinese Academy of Sciences Beijing 100093 China) (Zhejiang Normal University Jinhua 321004 China) (Research Center of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Beijing 100093 China)

We compiled and identified a list of chinese endemic seed plant species based on a large number of published references and expert reviews. The characters of these seed plant species and their distribution patterns were described at length. china is rich in endemic seed plants, with a total of 14 939 species (accounting for 52.1% of its total seed plant species) belonging to 1584 genera and 191 families. Temperate families and genera have a significantly higher proportion of endemism than cosmopolitan and tropical ones. The most primitive and derived groups have significantly higher endemism than the other groups. The endemism of tree, shrub, and liana or vine is higher than that of total species; in contrast, the endemism of herb is lower than that of total species. Geographically, these chinese endemic plants are mainly distributed in Yunnan and Sichuan provinces, southwest china. Species richness and proportion of these endemic plants decrease with increased latitude and have a unimodal response to altitude. The peak value of proportion of endemism is at higher altitudes than that of total species and endemic species richness. The proportions of endemic shrub, liana or vine, and herb increase with altitude and have a clear unimodal curve. In contrast, the proportion of tree increases with altitude, with a sudden increase at ～4000 m and has a completely different model. To date, our study provides the most comprehensive list of chinese endemic seed plant species and their basic composition and distribution features.

关键词： biodiversity conservation distribution pattern endemism flora of china seed plants.

SOLID PHASE TRANSITION OF SYNDIOTACTIC POLYSTYRENE IN SUPERCRITICAL CO_2

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chinese Journal of Polymer Science 2002年第3期20卷 191-196页

作者： Yu-ying Li Jia-song He State key laboratory of Engineering Plastics, Center for Molecular Science, institute of Chemistry chinese academy of sciences, beijing 100080 china Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences State Key Laboratory of Engineering Plastics 北京 100080

Solid phase transition of the a form crystals to the 3 form crystals in syndiotactic polystyrene (sPS) samples has occurred in supercritical CO2. This transformation is different from those detected under other conditions. The effects of some factors (e.g. time, temperature, and pressure) on the solid phase transformation of sPS in supercritical CO2 were analyzed in detail. Experimental results show that longer time, higher temperature or higher pressure favors the transformation of the a form crystals to the beta form crystals.

关键词： solid phase transition syndiotactic polystyrene supercritical CO2

Carbon Storage and Vertical Distribution in Three Shrubland Communities in Gurbantünggüt Desert,Uygur AutonomousRegion of Xinjiang,Northwest china

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chinese Geographical Science 2012年第5期22卷 541-549页

作者： GONG Yanming 1 ,HU Yukun 1 ,FANG Fei 1 ,LIU Yanyan 1 ,LI Kaihui 1 ,ZHANG Guangming 2 (1.key laboratory of Biogeography and Bioresource in Arid Land,Xinjiang institute of Ecology and Geography,chinese academy of sciences,Urumqi 830011,china 2.State key laboratory of Vegetation and Environmental Change, institute of Botany,chinese academy of sciences,beijing 100093,china) key laboratory of Biogeography and Bioresource in Arid Land Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi China State key laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China

This study was carried out in the Gurbantünggüt Desert,Uygur Autonomous Region of Xinjiang,Northwest china in August,*** quantify the storage,contribution and vertical distribution patterns of plant biomass carbon (PBC)and soil organic carbon(SOC)in the study area,we investigated the carbon concentrations and its vertical distribution in three different desert shrubland communities dominated by Reaumuria soongorica,Haloxylon ammodendron+*** and Tamarix ramosissima+***,*** analyzed vertical distribution of root biomass carbon and soil carbon contents by excavating soil profiles for each dominated *** results show that SOC is considerably the larger carbon pool in the soil layers of 1.0-3.0 m(the mean value of three shrubland communities is 38.46%)and 3.0-5.0 m(the mean value is 40.24%).In contrast,70.74%of belowground biomass carbon storage in 0-1.0 m layer,and its content decrease with increasing soil *** Haloxylon ammodendron+R. soongorica shrubland community has the highest belowground biomass carbon among three selected communities. This study highlights the importance of SOC stored in deep soil layers(lower than 3.0 m from the surface)in arid shrubland communities in the global carbon *** addition,it provides the data support for revealing deep soil solid carbon potential,and offers scientific basis for the further research in the carbon cycle of terrestrial ecosystem.

关键词： shrubland community plant biomass carbon soil organic carbon vertical distribution Gurbantünggüt desert

Oxygen Permeation Behaviors and Hardening Effect of Titanium Alloys at High Temperature

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Journal of Materials Science & Technology 2004年第6期20卷 719-723页

作者： Hongyan MA, Maocai WANG and Weitao WUState key laboratory for Corrosion and Protection, institute of Metai Research, chinese academy of sciences, Shenyang 110016, chinaGraduate School of the chinese academy of sciences, beijing 100039, china Lab. for Corrosion and Protection Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China Graduate Sch. Chinese Acad. of Sci. Beijing 100039 China

In order to improve the surface hardness and wear resistance of Ti and Ti alloy components, an oxygen permeation treatment (OPT) was developed. The oxygen permeation behaviors of three Ti alloys, TA2, TB5 and TC11, treated in air with O-P medium at high temperature have been studied. The results show that the 0-P treatment can significantly improve the surface hardness of Ti alloys. The oxidation mass-gain of β-Ti alloy (TB5) is much higher than α-Ti alloy (TA2) under the same condition, while α+β Ti alloy (TC11) is the lowest. All the Ti alloys treated at this condition produce two surface layers: the outer layer consists mainly of TiO2, as well as trace of other oxides, and the inner layer consists of a Ti-O interstitial solid solution formed by the diffusion of oxygen in α crystal lattice. Thick scales of β Ti alloy (TB5) are easily formed depending mainly on the poor solid solution content of oxygen, while deep solution layer can be formed since partial β phase has been transformed into α phase. The scales of α-β Ti alloy (TC11) are very thin and compact. Aluminum-rich zone, as well as deficient zone, is found in oxide layers. A crystallographic characterization of oxygen solution layer has been performed and evaluated by crystallographic lattice constant.

关键词： Microstructure Oxygen permeation Titanium Solid solution

Improved multi-pass fast correlation attacks with applications

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Science china(Information sciences) 2011年第8期54卷 1635-1644页

作者： ZHANG Bin & FENG DengGuo State key laboratory of Information Security,institute of Software,chinese academy of sciences,beijing 100190,china State key laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing China

In this paper we propose two new algorithms for multi-pass fast correlation attacks on stream *** first algorithm aims at fast symbol-wise decoding in the circumstances that the noise is not very high and we have little resource for *** second algorithm deals with the practical decoding problem in the high noise and limited keystream *** new algorithms are applicable to arbitrary form LFSR and compare favorably to the previously known algorithms in the scenarios under *** applications,we demonstrate new key recovery attacks on one-level Bluetooth E0 and LILI-128,*** 2 37 -bit keystream and 2 28-byte memory,our attack against one-level E0 needs 2 35.1 *** 2 24-bit keystream and 2 24.5 -byte memory,our attack on LILI-128 has time complexity 2 70.6 operations.

关键词： stream cipher fast correlation attacks linear feedback shift register (LFSR) Bluetooth E0 LILI-128

Cosmogenic ^(21)Ne concentrations and exposure ages of summit bedrocks in the Grove Mountains,Antarctica

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Science china Earth sciences 2010年第4期53卷 518-521页

作者： KONG Ping1,2,DING Lin2,LAI QingZhou2 & HUANG FeiXin3 1 key laboratory of the Earth’s Deep Interior,institute of Geology and Geophysics,chinese academy of sciences,beijing 100029,china 2 key laboratory of Continental Collision and Plateau Uplift,institute of Tibetan Plateau Research,chinese academy of sciences,beijing 100085,china 3 institute of Mineral Resources Research,china Metallurgical Geology Bureau,beijing 100025,china key laboratory of the Earth’s Deep Interior Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China key laboratory of Continental Collision and Plateau Uplift Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China institute of Mineral Resources Research China Metallurgical Geology Bureau Beijing China

Various sources of 21Ne and 22Ne exist in surface rocks:cosmogenic,in situ nucleogenic from internal U and Th,trapped crustal nucleogenic and trapped *** paper reports the first measurement,in china,of cosmogenic 21Ne and 22Ne in surface *** developed a unique sample pre-treatment procedure that effectively removed inclusions inside quartz grains,and thus maximally reduced nucleogenic contributions of 21Ne and ***-heating experiments show that concen-trations of cosmogenic 21Ne and 22Ne in summit bedrock samples R9202 and R9203 from Grove Mountains,Antarctica,are(3.83±0.87)×108 and(5.22±0.51)×108 atoms/g,*** corresponding minimum exposure ages are 2.2±0.5 and 3.0±0.3 *** indicates that the ice sheet in East Antarctica was uncovered the crest of Mount Harding,a typical nunatak in Grove Mountains,since at least mid-Pliocene.

关键词： 21Ne cosmogenic nuclide exposure age Antarctica Grove Mountains